JP7451081B2 - laminated polypropylene film - Google Patents

Description

The present invention relates to a laminated polypropylene film comprising a film using a polypropylene resin and a thin film layer containing an inorganic compound as a main component. More specifically, the present invention relates to a laminated polypropylene film that has excellent gas barrier properties and can be suitably used in various fields where dimensional stability and high rigidity at high temperatures are required.

Conventionally, stretched polypropylene films have excellent flexibility and moisture resistance, so they have been used for a wide range of purposes, including packaging for food and various other products, electrical insulation, and surface protection films.
However, for food applications, films are often required to have oxygen gas barrier properties in order to preserve them, and conventional laminated films made of polypropylene films with inorganic compounds vapor-deposited do not have sufficient oxygen gas barrier properties. A product prepared by coating and drying a liquid containing a resin with gas barrier properties has been used.
However, there is a limit to reducing production costs because there is a process of applying and drying a liquid containing dissolved oxygen gas barrier resin.Moreover, the thickness of the oxygen gas barrier resin layer must be approximately 5 μm, which reduces the lamination process. There were problems in that it was time consuming and the cost of raw materials was high.
Furthermore, the thickness of the laminated film is large, making it difficult to print, seal, and make bags.
Therefore, there has been a demand for a laminated film that has excellent oxygen gas barrier properties by vapor-depositing a thin film of an inorganic compound on a polypropylene film, but a laminated film in which an inorganic compound is directly vapor-deposited on a polypropylene film does not have gas barrier properties (for example, (See Patent Documents 1 and 2.)

Japanese Patent Application Publication No. 11-105190 Japanese Patent Application Publication No. 2000-355068

The present invention has been made against the background of such problems of the prior art. That is, the object of the present invention is to provide a polypropylene film base material using a polypropylene resin and an inorganic compound as a main material, which has gas barrier properties comparable to polypropylene films coated with polyvinylidene chloride, is low cost, and has excellent processability. An object of the present invention is to provide a laminated polypropylene film comprising a thin film layer as a component.

The present inventor has completed the present invention as a result of intensive studies to achieve the above object. That is, the laminated polypropylene film of the present invention is a laminated polypropylene film comprising a polypropylene film base material using a polypropylene resin and a thin film layer containing an inorganic compound as a main component. This is a laminated polypropylene film characterized by a heat shrinkage rate of 7% or less and an oxygen permeability of 150 mL/m ² /day/MPa or less.

Conventional laminated polypropylene films have a shrinkage rate of 9% or more in the longitudinal direction at 150°C, and when an inorganic compound is vapor-deposited onto a polypropylene film base material, thermal energy possessed by the vapor-deposited particles or radiant heat from the crucible containing the inorganic compound is generated. It is estimated that this caused the polypropylene film base material to shrink, and that this caused a change in the inorganic compound layer itself that decreased its gas barrier properties.

In this case, it is preferable that the laminated polypropylene film has a haze of 6% or less.

In this case, it is preferable that the laminated polypropylene film has a transverse heat shrinkage rate of 7% or less at 150°C.
In this case, a laminate containing the above-mentioned laminated polypropylene film and polyolefin film is suitable.

According to the laminated polypropylene film of the present invention, it can have an oxygen gas barrier property comparable to that of a polypropylene film coated with polyvinylidene chloride, and as a result, it can be made thinner.
Furthermore, the laminated polypropylene film of the present invention not only has oxygen gas barrier properties at room temperature, but also maintains its oxygen gas barrier properties and other physical properties even when exposed to an environment of about 150°C. It is preferably applied in a wide range of applications because it requires oxygen gas barrier properties that were unimaginable with polypropylene films and can be used in high-temperature environments.
For example, by using the laminated polypropylene film of the present invention as a base layer and laminating a heat-sealing layer on the surface layer of the base layer, it can be used for various packaging forms that require heat sealability. Alternatively, when heat-sealing a laminated film using this, the heat-sealing temperature can be set high and the heat-sealing strength improves, making it possible to increase the line speed in bag-making processing etc., increasing productivity. will improve. It can also be used as a base material for extrusion laminates that have a large heat load.
Furthermore, the amount of deformation of the bag can be suppressed even when performing high-temperature processing such as retorting after bag making.

It is a chart for explaining the azimuth angle dependence and 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 polypropylene film used as the base material of the laminated polypropylene film.

The present invention relates to a laminated polypropylene film having excellent gas barrier properties, dimensional stability at high temperatures, and mechanical properties.
The laminated polypropylene film of the present invention is a laminated polypropylene film comprising a polypropylene film base material using a polypropylene resin and a thin film layer containing an inorganic compound as a main component. The present invention is a laminated polypropylene film characterized by having an oxygen permeability of 7% or less and an oxygen permeability of 150 mL/m ² /day/MPa or less.

[Inorganic thin film layer]
The inorganic thin film layer used in the present invention contains an inorganic compound as a main component, and the inorganic compound is preferably an inorganic oxide. The inorganic oxide is preferably at least one of aluminum oxide and silicon oxide, or a composite oxide thereof.
The "main component" here means that the total amount of aluminum oxide, silicon oxide, and composite oxide of aluminum oxide and silicon oxide is more than 50% by mass relative to 100% by mass of the components constituting the thin film layer. However, it is preferably 70% by mass or more, more preferably 90% by mass or more, and most preferably 100% by mass (components other than aluminum oxide and silicon oxide are not contained as components constituting the thin film layer).
The aluminum oxide herein is composed of at least one kind of various aluminum oxides such as AlO, Al ₂ O, Al ₂ O ₃ , etc., and the content of various aluminum oxides can be adjusted depending on the manufacturing conditions of the thin film layer. can. Silicon oxide is composed of at least one kind of various silicon oxides such as SiO, SiO ₂ , Si ₃ O ₂ and the like, and the content rate of various silicon oxides can be adjusted depending on the manufacturing conditions of the thin film layer. The composite oxide of aluminum oxide and silicon oxide consists of AlxSiy (x=1 to 2, y=1 to 3), and the content of various silicon oxides can be adjusted depending on the conditions for forming the thin film layer. Aluminum oxide, silicon oxide, and composite oxides of aluminum oxide and silicon oxide may contain other components in trace amounts (up to 3% of the total components) as long as the properties are not impaired. .
Components other than the "main component" include compounds such as titanium oxide, magnesium oxide, zirconium oxide, cerium oxide, zinc oxide, and mixtures thereof.

The thickness of the inorganic thin film layer is not particularly limited, but from the viewpoint of gas barrier properties and flexibility, it is preferably 5 to 500 nm, more preferably 10 to 200 nm, and even more preferably 15 to 50 nm. If the thickness of the thin film layer is less than 5 nm, it may be difficult to obtain satisfactory gas barrier properties.On the other hand, even if the thickness exceeds 500 nm, a corresponding effect of improving gas barrier properties cannot be obtained, and the bending resistance and This is rather disadvantageous in terms of manufacturing costs.

[Laminated polypropylene film]
The laminated polypropylene film of the present invention is particularly characterized by the physical properties of the laminated film. The laminated polypropylene film of the present invention exhibits the following film properties. In addition, each of the following physical properties is measured and evaluated by the method described later in Examples.
(Heat shrinkage rate)
The laminated polypropylene film of the present invention is a stretched film mainly composed of polypropylene resin, and needs to have a longitudinal heat shrinkage rate of 7% or less at 150°C. Here, the longitudinal direction is the direction in which the film flows (sometimes referred to as the length direction or longitudinal direction), and the lateral direction is the direction perpendicular to the direction of film flow (also referred to as the lateral direction or width direction). There are also). Conventional laminated polypropylene films have a longitudinal heat shrinkage rate of 9% or more at 150°C.

The upper limit of the 150° C. heat shrinkage rate in the longitudinal direction of the laminated polypropylene film of the present invention is preferably 6%, more preferably 5%, and still more preferably 4%. Gas barrier properties are better when the upper limit of the 150° C. heat shrinkage rate in the longitudinal direction is within the above range.

When an inorganic compound is vapor-deposited onto a polypropylene film substrate, the film made of a propylene-based polymer may shrink due to thermal energy possessed by the inorganic compound molecules used as the vapor-deposition material or radiant heat from the crucible containing the inorganic compound. It is presumed that if the degree of shrinkage of the polypropylene film base material during the formation of the inorganic thin film layer was small, it became difficult for gas to pass through. The reason is that if the polypropylene film base material shrinks during the formation of the inorganic thin film layer, the inorganic thin film layer may be destroyed due to bumps on the base material surface, or it may become difficult to form a dense inorganic thin film layer.
The lower limit of the 150°C heat shrinkage rate in the longitudinal direction is preferably 0.2%, more preferably 0.3%, even more preferably 0.5%, particularly preferably 0.7%. , most preferably 1.0%. When the lower limit of the 150° C. heat shrinkage rate in the longitudinal direction is within the above range, practical manufacturing may be facilitated in terms of cost, etc., and thickness unevenness may be reduced.
The upper limit of the 150°C heat shrinkage rate in the transverse direction of the laminated polypropylene film of the present invention is preferably 7%, more preferably 6%, still more preferably 5%, and particularly preferably 4%. . If the upper limit of the heat shrinkage rate at 150°C in the lateral direction is within the above range, when heat sealing is performed on a laminated polypropylene film or a laminated film using the same, the adhesive strength (heat seal Strength) is improved, making it possible to increase the line speed in bag-making processing, etc., and improving productivity. Furthermore, the amount of deformation of the bag can be suppressed even when performing high-temperature processing such as retorting after bag making.
The lower limit of the 150°C heat shrinkage rate in the transverse direction is preferably 0.2%, more preferably 0.3%, still more preferably 0.5%, particularly preferably 0.7%. , most preferably 1.0%. When the lower limit of the 150° C. heat shrinkage rate in the lateral direction is within the above range, practical manufacturing may be facilitated in terms of cost, etc., and thickness unevenness may be reduced.

(Oxygen permeability)
In the present invention, the upper limit of the oxygen permeability of the laminated polypropylene film at a temperature of 23° C. and a relative humidity of 65% needs to be 150 mL/m ² /day/MPa or less. More preferably 130 mL/m ² /day/MPa or less, even more preferably 120 mL/m ² /day/MPa, even more preferably 100 mL/m ² /day/MPa, particularly preferably It is 90 mL/m ² /day/MPa or less. When the upper limit of oxygen permeability exceeds 150 mL/m ² /day/MPa, the storage stability of substances and foods that deteriorate due to oxygen will be poor. The lower limit of the oxygen permeability of the laminated polypropylene film at a temperature of 23° C. and a humidity of 65% is not particularly limited, but is preferably 0.1 mL/m ² /day/MPa or more. Further, from the viewpoint of manufacturing, 0.1 mL/m ² /day/MPa is considered to be the lower limit.

(Haze)
The upper limit of the haze of the laminated polypropylene film of the present invention is preferably 6%, more preferably 5%, still more preferably 4.5%, even more preferably 4%, and particularly preferably 3%. .5%. When the upper limit of haze is within the above range, it may be easier to use in applications requiring transparency. In order to keep the haze to 6% or less, it is preferable that the inorganic thin film layer be transparent.
The lower limit of the haze of the laminated polypropylene film of the present invention is, as a practical value, preferably 0.1%, more preferably 0.2%, still more preferably 0.3%, and particularly preferably 0. .4%.

[Polypropylene film base material]
The polypropylene film base material used in the laminated polypropylene film of the present invention is particularly characterized by film physical properties. The stretched polypropylene film of the present invention exhibits the following film properties. Note that each physical property below is a value measured and evaluated, for example, by a method described later in Examples.

(Heat shrinkage rate)
The polypropylene film base material used in the present invention is a stretched film mainly composed of polypropylene resin, and the upper limit of the longitudinal heat shrinkage rate at 150°C is preferably 10%, more preferably 9%. %, more preferably 7%, particularly preferably 5%. Conventional polypropylene film has a heat shrinkage rate of 150° C. in the longitudinal direction of 11% or more. By setting the heat shrinkage rate of the polypropylene film base material to 10% or less, the longitudinal heat shrinkage rate at 150° C. of the laminated polypropylene film of the present invention can be set to 7% or less.
Further, the polypropylene film base material used in the present invention is a stretched film mainly composed of polypropylene resin, and preferably has a transverse heat shrinkage rate of 15% or less at 150°C, more preferably 9 %, more preferably 7%, particularly preferably 7%. Conventional polypropylene films have a 150°C heat shrinkage rate of 16% or more in the transverse direction. By setting the heat shrinkage rate of the polypropylene film base material to 10% or less, the lateral heat shrinkage rate at 150° C. of the laminated polypropylene film of the present invention can be made 7% or less.
Here, the longitudinal direction is the flow direction of the film (sometimes referred to as the length direction), and the lateral direction is the direction perpendicular to the flow direction of the film (sometimes referred to as the width direction).

The lower limit of the 150°C heat shrinkage rate in the longitudinal and transverse directions of the polypropylene film base material used in the present invention is preferably 0.2%, more preferably 0.3%, and still more preferably 0.5%. %, particularly preferably 0.7%, and most preferably 1.0%. When the 150° C. heat shrinkage rate is within the above range, practical manufacturing may be facilitated in terms of cost, etc., and thickness unevenness may be reduced.
It should be noted that if the 150°C heat shrinkage rate is up to about 1.5%, it is possible, for example, by increasing the low molecular weight component of polypropylene in the film base material or adjusting the stretching conditions and heat setting conditions of the film. In order to lower it to 1.5% or less, it is preferable to perform offline annealing treatment.

(Haze)
The lower limit of the haze of the polypropylene film base material used in the present invention is, as a practical value, preferably 0.1%, more preferably 0.2%, still more preferably 0.3%, and particularly preferably is 0.4%. The upper limit of haze is preferably 6%, more preferably 5%, still more preferably 4.5%, particularly preferably 4%, and most preferably 3.5%. When the haze is within the above range, it may be easier to use in applications requiring transparency. Haze tends to worsen, for example, when the stretching temperature and heat setting temperature are too high, when the cooling roll (CR) temperature is high and the cooling rate of the stretched raw sheet is slow, and when the low molecular weight is too high. By adjusting it, it can be controlled within the above range.

(thickness)
The lower limit of the thickness of the polypropylene film base material used in the present invention is 3 μm, preferably 4 μm, and more preferably 8 μm.
When the lower limit of the film thickness is less than 3 μm, the laminated polypropylene film tends to curl, and gas barrier properties tend to deteriorate.
In terms of processability of the film thickness, the upper limit is preferably 300 μm, more preferably 250 μm, even more preferably 200 μm, even more preferably 150 μm, particularly preferably 100 μm, and most preferably 50 μm. be.

(Impact resistance)
The lower limit of the impact resistance (23° C.) of the polypropylene film base material used in the present invention is preferably 0.6 J, more preferably 0.7 J. When the impact resistance is within the above range, the film has sufficient toughness and will not break during handling. From a practical standpoint, the upper limit of impact resistance is preferably 2J, more preferably 1.8J, still more preferably 1.6J, particularly preferably 1.5J. For example, if there are many low molecular weight components of polypropylene in the film base material, if the overall molecular weight is low, if there are few high molecular weight components of polypropylene in the film base material, or if the molecular weight of the high molecular weight components is low, impact resistance Since the impact resistance tends to decrease, the impact resistance can be controlled within the above range by adjusting these factors depending on the application.

(Young's modulus)
When the polypropylene film base material used in the present invention is a biaxially stretched film, the lower limit of Young's modulus (23° C.) in the machine direction is preferably 2 GPa, more preferably 2.1 GPa, still more preferably 2. 2 GPa, particularly preferably 2.3 GPa, most preferably 2.4 GPa. The upper limit of Young's modulus in the longitudinal direction is preferably 4 GPa, more preferably 3.7 GPa, even more preferably 3.5 GPa, particularly preferably 3.4 GPa, and most preferably 3.3 GPa. . When the Young's modulus in the longitudinal direction is within the above range, practical production is easy and the longitudinal-lateral balance may be improved.

When the polypropylene film used for the base material of the present invention is a biaxially stretched film, the lower limit of Young's modulus in the transverse direction (23°C) is preferably 3.8 GPa, more preferably 4 GPa, and still more preferably 4 GPa. .1 GPa, particularly preferably 4.2 GPa. The upper limit of Young's modulus in the lateral direction is preferably 8 GPa, more preferably 7.5 GPa, even more preferably 7 GPa, particularly preferably 6.5 GPa. When the Young's modulus in the transverse direction is within the above range, practical manufacture is easy, and the balance between the Young's modulus in the longitudinal direction and the transverse direction may be improved. The Young's modulus in the longitudinal and transverse directions can be increased, for example, by increasing the stretching ratio in each direction, and when stretching in the longitudinal direction followed by transverse stretching, the longitudinal stretching ratio should be set lower. The Young's modulus in the lateral direction can be increased by setting a high lateral stretching ratio.

(Thickness uniformity)
The lower limit of the uniformity of the thickness of the polypropylene film base material used in the present invention is preferably 0%, more preferably 0.1%, still more preferably 0.5%, and particularly preferably 1%. be. The upper limit of the thickness uniformity is preferably 20%, more preferably 17%, even more preferably 15%, particularly preferably 12%, and most preferably 10%. When the thickness uniformity is within the above range, defects are less likely to occur during post-processing such as coating and printing, and it is easy to use in applications that require precision.

(film density)
The lower limit of the density of the polypropylene film base material used in the present invention is preferably 0.910 g/cm ³ , more preferably 0.911 g/cm ³ , even more preferably 0.912 g/cm ³ , and especially Preferably it is 0.913 g/cm ³ . When the film density is within the above range, the crystallinity may be high and the heat shrinkage rate may be low. The upper limit of the film density is preferably 0.930 g/cm ³ , more preferably 0.928 g/cm ³ , even more preferably 0.926 g/cm 3 , particularly preferably 0.925 g/cm ³ be. If the film density exceeds the above upper limit, production may become difficult in practice. The film density can be increased by increasing the stretching ratio and stretching temperature, increasing the heat setting temperature, and further performing offline annealing.

(Refractive index)
The lower limit of the longitudinal refractive index (Nx) of the polypropylene film base material used in the present invention is preferably 1.502, more preferably 1.503, and even 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 transverse refractive index (Ny) of the polypropylene film base material used in the present invention 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 polypropylene film base material used in 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 even more preferably 1.505.

(planar orientation coefficient)
The lower limit of the planar orientation coefficient of the polypropylene film used as the base material of the present invention is preferably 0.0125, more preferably 0.0126, still more preferably 0.0127, and particularly preferably 0.0128. It is. As a practical value, the upper limit of the planar orientation coefficient is preferably 0.0155, more preferably 0.0150, still more preferably 0.0148, and particularly preferably 0.0145. The plane orientation coefficient can be controlled within a range by adjusting the stretching ratio. When the plane orientation coefficient is within this range, the thickness unevenness of the film tends to be improved.

(Film orientation)
Polypropylene film substrates generally have crystal orientation, and the direction and degree of this orientation have a large effect on the physical properties of the film. The degree of crystal orientation varies depending on the molecular structure of the polypropylene used and the process and conditions in film production. In addition, the orientation direction of a stretched polypropylene film can be determined by wide-angle X-ray diffraction method, in which X-rays are incident perpendicularly to the film surface and the azimuthal dependence of the scattering peak derived from crystals is measured. can. Specifically, a stretched polypropylene film typically has a monoclinic α-type crystal structure. When the azimuthal dependence of the scattering intensity of 110 planes (planar spacing: 6.65 angstroms) is measured by wide-angle X-ray diffraction, the α-type crystal has a strong orientation mainly in one axis. That is, when the scattering intensity derived from the 110 plane of the α-type crystal is plotted against the azimuth angle, the strongest peak is observed in the direction perpendicular to the orientation of the molecular axis. In the present invention, the degree of orientation is defined by the half width of this maximum peak.
Note that FIG. 1 shows a typical pattern of the azimuthal dependence of scattering originating from the 110 plane of the α-type crystal of polypropylene. Further, in FIG. 1, the half-value widths of the main peaks (maximum peak, azimuth angles of 180° and 360°) of the 110 plane are shown.

In the polypropylene film used as the base material of the present invention, it is preferable that the half width of the maximum peak when the scattering intensity of the 110 plane measured by wide-angle X-ray scattering is plotted against the azimuth angle is 30 degrees or less. The upper limit of this half width is more preferably 29 degrees, and still more preferably 28 degrees. If the half-width of the azimuthal angle dependence of the scattering intensity derived from the 110 plane is larger than the above range, the orientation will be insufficient and the heat resistance and rigidity will not be sufficient. The lower limit of the half width of the azimuth dependence of the scattering intensity derived from the 110 plane is preferably 5 degrees, more preferably 7 degrees, and even more preferably 8 degrees. If the half width of the 110 plane is smaller than the above range, impact resistance may be lowered or orientation cracking may occur.

(Wide-angle X-ray diffraction device)
The half-width defined above is preferably measured using highly parallel X-rays, and synchrotron radiation is preferably used.
The X-ray source used for wide-angle X-ray diffraction measurements may be general equipment such as a tube type or rotary type used in laboratories, but a high-intensity light source that is highly parallel and can irradiate high-intensity synchrotron radiation is recommended. It is preferable to use With synchrotron radiation, X-rays are difficult to spread and have high brightness, so measurements can be performed with high precision and in a short time.For example, even film samples several tens of microns thick can be measured with a single film without stacking them. Moreover, since highly accurate measurement is possible, detailed evaluation of crystal orientation becomes possible. On the other hand, when measuring a film sample with a thickness of several tens of microns using low-brightness X-rays, it will take a long time to measure unless multiple sheets are stacked, and if multiple sheets are stacked, minute deviations may occur. Therefore, when the scattering intensity of the 110 plane is plotted against the azimuth angle, the peak becomes broad, and the obtained half-width value tends to become large.
Examples of facilities that can irradiate synchrotron radiation with high parallelism and high brightness include large synchrotron radiation facilities such as SPring-8. It is preferable to measure the half width of the present invention using beam line BL03XU.

(Long period structure/Small angle X-ray scattering (SAXS))
The polypropylene film base material used in the present invention preferably has a large long period size. Generally, a crystalline polymer has a regular stacked structure (periodic structure) consisting of repeating crystals and amorphous layers. Here, the size of the repeating unit consisting of crystals and amorphous is called the long period size. This long-period size can be determined from the scattering peak angle derived from the long-period structure in the main orientation direction measured by small-angle X-ray scattering.

It is preferable that the long-period scattering peak of the polypropylene film used as the base material of the present invention is clearly observed in the main orientation direction when measured by small-angle X-ray scattering. Here, the main orientation direction refers to the direction in which scattering due to the long period of the polymer crystal is more strongly observed in the two-dimensional X-ray scattering pattern. In the case of uniaxial stretching, the main orientation direction often coincides with the stretching direction, and in the case of sequential biaxial stretching of longitudinal stretching and lateral stretching, the main orientation direction coincides with the lateral stretching direction, although it depends on the respective stretching ratios. often match. The more clearly a long-period peak due to polymer crystals is observed, the more highly ordered a long-period structure is formed.

In the polypropylene film used as the base material of the present invention, the long period size obtained from the long period scattering peak is preferably 40 nm or more. The lower limit of the long period size is more preferably 41 nm, and even more preferably 43 nm. If the long period size is smaller than the above range, the melting peak temperature will be low and therefore the heat resistance will tend to decrease. The upper limit of the long period size is preferably 100 nm, more preferably 90 nm, and even more preferably 80 nm. If the long period size is larger than the above range, crystallization or heat treatment will take a long time, which tends to make practical production difficult.

(Small angle X-ray diffraction device)
There are no particular restrictions on the X-ray source used for small-angle X-ray scattering measurements, and general equipment used in laboratories, such as a tube type or rotary type, can be used. It is preferable to use a high-brightness light source that can emit synchrotron radiation with high brightness, similar to the X-ray generation source used in the above. In particular, when the polypropylene film base material used in the present invention has a large long period, X-ray scattering originating from the long period structure is in a smaller angle region. Therefore, since the X-ray beam diameter is large and difficult to measure using a laboratory X-ray device with a short camera length, the X-rays do not spread easily and the beam diameter can be narrowed down to several hundred microns or less, and It is preferable to measure extremely small angle regions using synchrotron radiation with high brightness and a long camera length. At this time, the camera length is preferably 7 m or more.

[Polypropylene resin]
The polypropylene resin used for the polypropylene film base material of the present invention is not particularly limited, and examples include propylene homopolymers, copolymers with ethylene and/or α-olefins having 4 or more carbon atoms, and mixtures thereof. can be used.
The polypropylene resin constituting the film is preferably a propylene homopolymer that does not substantially contain a comonomer, and even when it contains a comonomer, the amount of the comonomer is preferably 0.5 mol % or less. The upper limit of the comonomer amount is preferably 0.3 mol%, more preferably 0.1 mol%. Within the above range, the crystallinity may be improved and the thermal shrinkage rate at high temperatures may be reduced. Note that a comonomer may be included in a trace amount within a range that does not significantly reduce crystallinity.
The polypropylene resin constituting the film is preferably a propylene homopolymer obtained only from propylene monomers, and even if it is a propylene homopolymer, it is most preferable that it does not contain heterogeneous bonds such as head-to-head bonds. preferable.

(Stereoregularity of polypropylene resin)
The lower limit of the mesopentad fraction measured by 13C-NMR, which is an indicator of the stereoregularity of the polypropylene resin constituting the film, is preferably 96%. The lower limit of the mesopentad fraction is preferably 96.5%, more preferably 97%. Within the above range, crystallinity may be improved and the thermal shrinkage rate at high temperatures may be lowered. The upper limit of the mesopentad fraction is preferably 99.8%, more preferably 99.6%, and even more preferably 99.5%. Within the above range, practical production may become easier.

The lower limit of the meso-average chain length of the polypropylene resin constituting the film is preferably 100, more preferably 120, and still more preferably 130. Within the above range, the crystallinity may be improved and the thermal shrinkage rate at high temperatures may be reduced. From a practical standpoint, the upper limit of the average meso chain length is preferably 5,000.

From a practical standpoint, the lower limit of the xylene soluble content of the polypropylene resin constituting the film is preferably 0.1% by mass. The upper limit of the xylene soluble content is preferably 7% by mass, more preferably 6% by mass, and even more preferably 5% by mass. Within the above range, the crystallinity may be improved and the thermal shrinkage rate at high temperatures may be reduced.

(Melt flow rate of polypropylene resin)
The lower limit of the melt flow rate (MFR) (230° C., 2.16 kgf) of polypropylene resin is 0.5 g/10 minutes. The lower limit of MFR is preferably 1.0 g/10 minutes, more preferably 1.3 g/10 minutes, still more preferably 1.5 g/10 minutes, even more preferably 2.0 g/10 minutes. It is particularly preferably 4.0 g/10 minutes, and preferably 6.0 g/10 minutes. Within the above range, the mechanical load is small and extrusion and stretching may become easy. The upper limit of MFR is 20 g/10 minutes, preferably 17 g/10 minutes, more preferably 16 g/10 minutes, even more preferably 15 g/10 minutes. Within the above range, stretching may become easier, thickness unevenness may become smaller, and the stretching temperature and heat setting temperature may be more likely to be raised, resulting in lower heat shrinkage.

(Molecular weight of polypropylene resin)
The lower limit of the number average molecular weight (Mn) measured by gel permeation chromatography (GPC) of the polypropylene resin constituting the film is preferably 20,000, more preferably 22,000, still more preferably 24,000, Particularly preferred is 26,000, most preferably 27,000. Within the above range, there may be advantages such as easier stretching, less uneven thickness, and easier raising of stretching temperature and heat setting temperature, resulting in lower heat shrinkage. The upper limit of Mn is preferably 200,000, more preferably 170,000, still more preferably 160,000, particularly preferably 150,000. Within the above range, the effects of the present invention, such as the low heat shrinkage rate at high temperatures of the polypropylene film base material, which is the effect of low molecular weight polypropylene resins, may be easily obtained, and stretching may be facilitated.

The lower limit of the mass average molecular weight (Mw) measured by GPC of the polypropylene resin constituting the film is preferably 180,000, more preferably 200,000, still more preferably 230,000, still more preferably 240,000, Particularly preferably 250,000, most preferably 270,000. Within the above range, there may be advantages such as easier stretching, less uneven thickness, and easier raising of stretching temperature and heat setting temperature, resulting in lower heat shrinkage. The upper limit of Mw is preferably 500,000, more preferably 450,000, still more preferably 420,000, particularly preferably 410,000, and most preferably 400,000. Within the above range, the mechanical load may be small and extrusion and stretching may be facilitated.

(Molecular weight distribution of polypropylene resin)
The polypropylene resin used in the present invention preferably has the following characteristics. That is, when measuring the gel permeation chromatography (GPC) integration curve of the polypropylene resin constituting the film, the lower limit of the amount of components with a molecular weight of 100,000 or less is preferably 35% by mass, more preferably 38% by mass. It is more preferably 40% by weight, particularly preferably 41% by weight, and most preferably 42% by weight. Within the above range, the effects of the present application such as a low heat shrinkage rate at high temperatures, which are the effects of low molecular weight materials, may be more easily obtained, and stretching may become easier. The upper limit of the amount of components with a molecular weight of 100,000 or less in the GPC integration curve is preferably 65% by mass, more preferably 60% by mass, even more preferably 58% by mass, and particularly preferably 56% by mass. , most preferably 55% by weight. Within the above range, stretching may be facilitated, thickness unevenness may be reduced, and the stretching temperature and heat setting temperature may be easily raised, resulting in a low heat shrinkage rate.

In the polypropylene resin used in the present invention, the lower limit of mass average molecular weight (Mw)/number average molecular weight (Mn), which is an index of the breadth of molecular weight distribution, is preferably 4, more preferably 4.5, More preferably, it is 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, and most preferably 20. When Mw/Mn is within the above range, practical production is easy.
The molecular weight distribution of polypropylene can be determined by polymerizing components with different molecular weights in multiple stages in a series of plants, by blending components with different molecular weights offline in a kneading machine, or by blending catalysts with different performances. It can be adjusted by using a catalyst that can realize a desired molecular weight distribution.

(Production method of polypropylene resin)
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 these, in order to eliminate heterogeneous bonds, it is preferable to use a catalyst capable of polymerization with high stereoregularity among Ziegler-Natta catalysts.
Any known method may be used to polymerize propylene, such as polymerization in an inert solvent such as hexane, heptane, toluene, or xylene, polymerization in a liquid monomer, or polymerization in a gaseous monomer. Examples include a method in which a catalyst is added and polymerization is carried out in a gas phase state, and a method in which a combination of these is polymerized.

(Additive)
Additives and other resins may be added to the polypropylene film base material used in the present invention, if necessary. Examples of additives include antioxidants, ultraviolet absorbers, antistatic agents, lubricants, nucleating agents, adhesives, antifogging agents, flame retardants, antiblocking agents, inorganic or organic fillers, and the like. Examples of other resins include polypropylene resins other than the polypropylene resin used in the present invention, random copolymers that are copolymers of propylene and ethylene and/or α-olefins having 4 or more carbon atoms, and various elastomers. It will be done. These can be polymerized sequentially using a multi-stage reactor, blended with polypropylene resin using a Henschel mixer, or master pellets prepared in advance using a melt kneader are diluted with polypropylene to a predetermined concentration. Alternatively, the entire amount may be melted and kneaded before use.

(Method for producing stretched polypropylene film)
The polypropylene film used as the base material of the present invention may be a uniaxially stretched film in the longitudinal direction (longitudinal direction) or the transverse direction (width direction), but it is preferably a biaxially stretched film. In the case of biaxial stretching, sequential biaxial stretching or simultaneous biaxial stretching may be used.

The most preferred method for producing a sequentially biaxially stretched film of longitudinal stretching and transverse stretching will be described below.
First, a polypropylene resin is heated and melted using a single-screw or twin-screw extruder, and extruded onto a chill roll to obtain an unstretched sheet. The melt extrusion conditions are such that the resin temperature is 200 to 280°C, extruded into a sheet through a T-die, and cooled and solidified with a cooling roll at a temperature of 10 to 100°C. Next, the film is stretched 3 to 8 times, preferably 3 to 7 times, in the length (longitudinal) direction using a stretching roll at 120 to 165°C, and then stretched in the transverse direction to 155 to 175°C, preferably 158 to 170°C. Stretching is carried out at a temperature of 4 to 20 times, preferably 6 to 12 times. Further, heat treatment is performed at an ambient temperature of 165 to 175°C, preferably 166 to 173°C, while allowing 1 to 15% relaxation. A roll sample can be obtained by subjecting the thus obtained polypropylene film to a corona discharge treatment on at least one side, if necessary, and then winding it up with a winder.

The lower limit of the stretching ratio in the longitudinal direction is preferably 3 times, more preferably 3.5 times. If the stretching ratio in the longitudinal direction is less than the above, film thickness may become uneven. The upper limit of the stretching ratio in the longitudinal direction is preferably 8 times, more preferably 7 times. If the stretching ratio in the longitudinal direction exceeds the above range, subsequent lateral stretching may become difficult.
The lower limit of the stretching temperature in the longitudinal direction is preferably 120°C, more preferably 125°C, and still more preferably 130°C. If the stretching temperature in the longitudinal direction is lower than the above, mechanical load may become large, thickness unevenness may become large, and surface roughness of the film may occur. The upper limit of the longitudinal stretching temperature is preferably 165°C, more preferably 160°C, even more preferably 155°C, particularly preferably 150°C. Although a higher stretching temperature is preferable for lowering the thermal shrinkage rate, it may adhere to the rolls, making it impossible to stretch or causing surface roughness.

The lower limit of the lateral stretching ratio is preferably 4 times, more preferably 5 times, and still more preferably 6 times. If the lateral stretching ratio is less than the above, thickness may become uneven. The upper limit of the transverse stretching ratio is preferably 20 times, more preferably 17 times, still more preferably 15 times, particularly preferably 12 times. If the lateral stretching ratio exceeds the above, the heat shrinkage rate may increase or breakage may occur during stretching.
The preheating temperature for transverse stretching is preferably set 5 to 15° C. higher than the stretching temperature in order to quickly raise the film temperature to around the stretching temperature.

The transverse stretching is preferably carried out at a temperature 3 to 5° C. higher than that of conventional stretched polypropylene films. The lower limit of the TD stretching temperature is preferably 155°C, more preferably 157°C, and even more preferably 158°C. If the lateral stretching temperature is below the above range, the film may not be sufficiently softened and may break, or the heat shrinkage rate may become high. The upper limit of the transverse stretching temperature is preferably 175°C, more preferably 170°C, and even more preferably 168°C. In order to lower the heat shrinkage rate, a higher transverse stretching temperature is preferable, but if it exceeds the above, low molecular weight components will melt and recrystallize, resulting in not only poor orientation but also surface roughness and whitening of the film. There are things to do.

The stretched film is usually heat set. In the present invention, heat setting can be performed at a temperature 3 to 10° C. higher than that of conventional stretched polypropylene films. The lower limit of the heat setting temperature is preferably 165°C, more preferably 166°C. If the heat setting temperature is lower than the above, the heat shrinkage rate may increase. Furthermore, a long treatment time is required to reduce the heat shrinkage rate, which may result in poor productivity. The upper limit of the heat setting temperature is preferably 175°C, more preferably 173°C. If the heat setting temperature exceeds the above range, low molecular weight components may melt and recrystallize, resulting in surface roughness and whitening of the film.

It is preferable to relax (relax) during heat fixation. The lower limit of relaxation is preferably 1%, more preferably 2%, and even more preferably 3%. If the relaxation is less than the above, the thermal shrinkage rate may increase. The upper limit of relaxation is preferably 10%, more preferably 8%. If the relaxation exceeds the above, the thickness may become uneven.

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

The lower limit of the off-line annealing time is preferably 0.1 minute, more preferably 0.5 minute, and still more preferably 1 minute. If the off-line annealing time is less than the above, 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, productivity may decrease.
It should be noted that if the 150°C heat shrinkage rate is up to about 1.5%, it is possible to do so by increasing the low molecular weight component or adjusting the stretching conditions and heat setting conditions, but it can be reduced to below 1.5%. , it is preferable to perform an annealing treatment off-line.
Haze tends to worsen, for example, when the stretching temperature and heat setting temperature are too high, when the cooling roll (CR) temperature is high and the cooling rate of the stretched raw sheet is slow, and when the low molecular weight is too high. By adjusting it, it can be controlled within the above range.

The stretched polypropylene film thus obtained is usually formed into a film having a width of about 2,000 to 12,000 mm and a length of about 1,000 to 50,000 m, and then wound into a roll. Furthermore, it is slit according to various uses and provided as a slit roll with a width of 300 to 2000 mm and a length of about 500 to 5000 m.

(Method for producing inorganic thin film layer)
For the production of the inorganic thin film layer, known manufacturing methods such as PVD methods (physical vapor deposition methods) such as vacuum evaporation method, sputtering method, and ion plating method, or CVD method (chemical vapor deposition method) are used as appropriate. A vapor deposition method is preferable, and a vacuum vapor deposition method is more preferable. For example, in the vacuum evaporation method, a mixture of Al ₂ O 3 and SiO ₂ or a mixture of Al and SiO ₂ is used as the evaporation source material, and heating methods include resistance heating, high-frequency induction heating, electron beam heating, etc. can be used. Furthermore, reactive vapor deposition using means such as introducing oxygen, nitrogen, water vapor, etc. as a reactive gas, or using ozone addition, ion assist, etc. may be used. Further, the production conditions may be changed as long as the object of the present invention is not impaired, such as by applying a bias or the like to the film base material, raising or lowering the temperature of the film base material, etc. The same applies to other manufacturing methods such as sputtering and CVD.
At this time, a coating layer may be provided between the polypropylene film base material and the inorganic thin film layer, or a coating layer may be provided on the inorganic thin film layer.

[Application]
The laminated polypropylene film of the present invention has the above-mentioned excellent properties not found in the prior art. When used as a packaging film, it not only can be used as a substitute for polypropylene film coated with polyvinylidene chloride due to its excellent gas barrier properties, but also can be made thinner due to its higher rigidity, further reducing costs and reducing costs. Can be made lighter.
In addition, the laminated polypropylene film of the present invention has high heat resistance, so it can be processed at high temperatures during coating and printing, improving production efficiency and making it possible to use coating agents, inks, laminating adhesives, etc. that were difficult to use in the past. can.
Furthermore, the laminated polypropylene film of the present invention is not limited to packaging, but can also be used as an insulating film for capacitors, motors, etc., and as a base film for backseats for solar cells.

(Method for producing laminate laminate)
Chemicals and cosmetics such as food and beverages, pharmaceuticals, detergents, shampoos, oils, toothpastes, adhesives, and pressure-sensitive adhesives can be produced using the laminate of the present invention, in which the laminated polypropylene film is provided with a polyolefin resin layer having heat-sealing properties. It is possible to produce packaging containers that are excellent in suitability for filling and packaging, storage suitability, etc. for various other articles.
As the polyolefin resin layer having heat-sealing properties, a film or sheet of resin that can be melted and bonded to each other by heat can be used, and specifically, for example, low density polyethylene, medium density polyethylene, High-density polyethylene, linear low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid Copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, methylpentene polymer, polybutene polymer, polyolefin resin such as polyethylene or polypropylene with acrylic acid, methacrylic acid, maleic acid, maleic anhydride. , acid-modified polyolefin resins modified with unsaturated carboxylic acids such as fumaric acid and itaconic acid, polyvinyl acetate resins, poly(meth)acrylic resins, polyvinyl chloride resins, and other various resin films. A sheet can be used. A typical example is a film or sheet made of linear low-density polyethylene or polypropylene.
The upper limit of the oxygen permeability of the laminate at a temperature of 23° C. and a relative humidity of 65% is preferably 50 mL/m ² /day/MPa, more preferably 30 mL/m ² /day/MPa, and Preferably it is 20 mL/m ² /day/MPa, particularly preferably 15 mL/m ² /day/MPa. When the upper limit of oxygen permeability is 50 mL/m ² /day/MPa, the storage stability of substances and foods that deteriorate due to oxygen is excellent. The lower limit of the oxygen permeability of the laminated polypropylene film at a temperature of 23° C. and a humidity of 65% is not particularly limited, but is preferably 0.1 mL/m ² /day/MPa. Further, from the viewpoint of manufacturing, 0.1 mL/m ² /day/MPa is considered to be the lower limit.

The lower limit of the longitudinal lamination strength of the laminate is preferably 1.1 N/15 mm, more preferably 1.2 N/15 mm, and still more preferably 1.2 N/15 mm. When the lower limit of the lamination strength in the vertical direction is 1.1 N/15 mm, the strength of the packaging container is excellent. The upper limit of the lamination strength in the longitudinal direction is not particularly limited, but is preferably 3.0 N/15 mm. Further, from a manufacturing point of view, 3.0N/15mm is considered to be the upper limit.

EXAMPLES The present invention will be explained in detail below based on Examples, but the present invention is not limited to these Examples. The methods for measuring physical properties in Examples are as follows.

1) stereoregularity)
Mesopentad fraction ([mmmm]%) and meso average chain length were measured using 13C-NMR as described below.
The mesopentad fraction was calculated according to the method described in Zambelli et al., Macromolecules, Vol. 6, p. 925 (1973).
The meso average chain length was calculated according to the method described in "Polymer Sequence Distribution" Chapter 2 (1977) by J.C. Randall (Academic Press, New York).
13C-NMR measurement was carried out at 110°C by dissolving 200 mg of the sample in a mixture of o-dichlorobenzene and heavy benzene at a ratio of 8:2 (volume ratio) at 135°C using "AVANCE 500" manufactured by BRUKER.

2) Xylene soluble content (unit: mass%)
1 g of 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. The ratio of the mass dissolved in the filtrate to the original sample amount was determined as mass%).

3) Melt flow rate (MFR, unit: g/10 minutes)
MFR was measured at a temperature of 230° C. and a load of 2.16 kgf in accordance with JIS K7210-1:2014.

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

The number average molecular weight (Mn), mass average molecular weight (Mw), and Z+1 average molecular weight (Mz+1) are each determined by the number of molecules (Ni) of the molecular weight (Mi) at each elution position of the GPC curve obtained through the molecular weight calibration curve. It is defined by the following formula.
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
Moreover, the molecular weight at the peak position of the GPC curve was defined as Mp.
When the baseline was not clear, the baseline was set in the range up to the lowest position on the high molecular weight side of the elution peak on the high molecular weight side that was closest to the elution peak of the standard substance.

5) Wide-angle X-ray diffraction In the embodiment of the present invention, the X-ray source direction and The measurement film was set so that the angle with the film surface was perpendicular, and wide-angle X-ray (WAXS) measurement was performed. The measurement conditions are shown below.
The X-ray wavelength is 0.1 nm, and the transmittance is calculated from the values of the ion chambers set before and after the sample, using an imaging plate (RIGAKU RAXIS VII) or a CCD camera with an image intensifier (Hamamatsu Photonics V7739P+ORCA R2) as a detector. did. Air scattering correction was performed on the obtained two-dimensional image in consideration of dark current (dark noise) and transmittance. The camera length was measured using cerium oxide (CeO ₂ ) and Fit2D (software manufactured by European Synchrotron Radiation Facility [http://www.esrf.eu/computing/scientific/FIT2D/]) (110). face The azimuth profile of

6) Long-period size using small-angle X-ray scattering method At the second hatch of the beam line BL03XU owned by the Frontier Soft Matter Development Industry-Academia Alliance (FSBL) in the large synchrotron radiation facility SPring-8, we measured the length of the film up and down, Small-angle X-ray (SAXS) measurements were performed by setting the measurement film so that the horizontal direction was left and right and the angle between the X-ray source direction and the film surface was perpendicular. The measurement conditions are shown below.
The X-ray wavelength was 0.2 nm, the camera length was approximately 7.7 m, and the detector was an imaging plate (RIGAKU R-AXIS VII) in the range of 0.01 to 0.5 (nm-1) of the scattering vector q. A scattering image was obtained. Here, the scattering vector q is calculated by the formula q=4πsinθ/λ, where θ is half of the scattering angle 2θ, π is pi, and λ is the wavelength of the X-ray. Air scattering correction was performed on the obtained scattering image in consideration of dark current (dark noise) and transmittance, as in WAXS measurement, and collagen separately calibrated with silver behenate was used for accurate camera length measurement. . The profile in the width direction of the sample was calculated using the aforementioned Fit2d software, and the scattering vector q (nm-1) was plotted 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 profile was set to ±5 degrees from the width direction.

7) Differential scanning calorimetry (DSC)
Heat measurement was performed using a differential scanning calorimeter (“DSC-60” manufactured by Shimadzu Corporation). Approximately 5 mg was cut out from the sample film and sealed in an aluminum pan for measurement. The temperature was raised from room temperature to 230°C at a rate of 20°C/min, and the melting endothermic peak temperature and melting endothermic peak area (total heat of fusion) of the sample were measured. Here, the baseline was set so that the curves would smoothly connect from the start of the endothermic peak to the end of the peak at temperatures before and after melting. Also, of the melting endothermic peak area, the area of the portion below 150°C was defined as the 150°C heat of fusion.

8) Heat shrinkage rate (unit: %)
It was measured by the following method in accordance with JIS Z 1712:2009. The film base material and the laminated film were each cut into 5 pieces each in the vertical and horizontal directions to a size of 20 mm in width and 200 mm in length, and the cut pieces were hung in a hot air oven at 150° C. and heated for 15 minutes. After heating, the length at marked lines at intervals of about 50 mm was measured, and the ratio (percentage) of the contracted length to the original length was defined as the heat shrinkage rate.

9) Young's modulus (unit: GPa)
The Young's modulus of the film base material and the laminated film in the longitudinal and transverse directions was measured at 23°C in accordance with JIS K 7127:1999. The film base material and the laminated film were cut into 5 pieces each in the vertical and horizontal directions with a width of 15 mm and a length of 200 mm, and cut at 200 mm/min. The tensile strength during a tensile test was measured at a tensile speed.

10) Impact resistance (unit: J)
Measurement was performed at 23° C. using a “Film Impact Tester (impact head: 12.7 mm)” manufactured by Toyo Seiki Co., Ltd. The film base material was cut into five pieces each with a width (horizontal direction) of 105 mm and a length (vertical direction) of 297 mm, and the impact strength was measured.

11) Thickness uniformity (thickness unevenness) (unit: %)
A square sample with a length of 1 m was cut out from the wound film roll and divided into 10 equal parts in the vertical and horizontal directions to prepare 100 samples for measurement. The thickness of the measurement sample was measured at approximately the center using a contact type film thickness meter. The average value A of the obtained 100 points of data is determined, and the difference (absolute value) B between the minimum and maximum values is determined, and the value calculated using the formula (B/A) x 100 is calculated as the thickness unevenness of the film. And so.

12) Haze (unit: %)
The film base material was measured according to JIS K7136:1999.

13) Film density (unit: g/cm ³ )
The density of the film base material was measured by the density gradient tube method according to JIS K7112:1999.

14) Refractive index (Nx, Ny, Nz)
The film base material was measured using an Abbe refractometer (manufactured by Atago Corporation) at 23° C., humidity 65%, benzyl alcohol as the measurement liquid, and measurement wavelength 589 nm (sodium D line). The refractive index along the vertical direction and the horizontal direction was set as Nx and Ny, respectively, and the refractive index in the thickness direction was set as Nz.

15) Planar orientation coefficient P
It was calculated from the formula: P=[(Nx+Ny)/2]-Nz using Nx, Ny, and Nz measured in 14) above.
(Composition and thickness of inorganic thin film layer)
The film thickness composition of the inorganic compound was measured using a fluorescent X-ray analyzer (ZSX100e manufactured by Rigaku Corporation) using a calibration curve prepared in advance. Note that the conditions for the excitation X-ray tube were 50 kV and 70 mA.
The calibration curve was obtained using the following procedure.
Several types of films with inorganic compound thin films made of aluminum oxide and silicon oxide were prepared, and the amounts of aluminum oxide and silicon oxide adhered to each were determined using the inductively coupled plasma emission method (ICP method). Next, each film whose adhesion amount was determined was analyzed using a fluorescent X-ray analyzer (Rigaku Corporation ZSX100e, excitation X-ray tube conditions: 50 kV, 70 mA) to detect fluorescent X-rays between aluminum oxide and silicon oxide of each sample. The strength was determined. Then, a calibration curve was created by determining the relationship between the fluorescent X-ray intensity and the amount of adhesion determined by ICP.
Since the adhesion amount determined by ICP is basically the mass, it was converted as follows to use it as the film thickness composition.
The film thickness was calculated assuming that the density of the inorganic oxide thin film was 80% of the bulk density, and that the volumes of aluminum oxide and silicon oxide were maintained even in a mixed state.
The content wa (mass %) of aluminum oxide in the film and the content ws (mass %) of silicon oxide in the film are the amount of aluminum oxide deposited per unit area Ma (g/cm 2 ), and the content of silicon oxide in the film is Ma (g/cm ² ). When the amount of adhesion per unit area is Ms (g/cm ² ), it is determined by the following formulas (1) and (2), respectively.
wa=100×[Ma/(Ma+Ms)] (1)
ws=100-wa (2)
That is, the amount of aluminum oxide deposited per unit area is Ma (g/cm ² ), its bulk density is ρa (3.97 g/cm ³ ), and the amount of silicon oxide deposited per unit area is Ms (g/cm 2 ). cm ² ), and its bulk density is ρs (2.65 g/cm ³ ), then the film thickness t (nm) is determined by the following equation (3).
t=((Ma/(ρa×0.8)+Ms/(ρs×0.8))×10 ⁷ ...Equation (3)
The film thickness measured using fluorescent X-rays was close to the film thickness actually measured using a transmission electron microscope (TEM).

16) Oxygen permeability (mL/m ² /day/MPa)
Using an oxygen permeability measuring device (OX-TRAN2/21 manufactured by MOCON), the polypropylene film base, the laminated polypropylene film, and the above laminate were measured at a temperature of 23° C. and a relative humidity of 65%. The side opposite to the inorganic thin film layer was made to be the humidity control side.

17) Water vapor transmission rate (g/m ²・day)
The amount of water vapor permeation was measured using a water vapor permeability measuring device (PERMATRAN-W3/33 manufactured by MOCON) under the conditions of a temperature of 37.8°C and a relative humidity of 90% using a polypropylene film base material, a laminated polypropylene film, and the following procedure. The produced laminate was measured. The surface opposite to the inorganic thin film layer was placed on the high humidity side.

18) Lamination strength Lamination strength was measured according to the following procedure.
1) Creation of a laminate with a sealant film A continuous dry laminating machine was used as follows.
After gravure coating the corona surface of the laminated polypropylene films obtained in Examples and Comparative Examples with an adhesive so that the dry coating amount was 3.0 g/ ^m2 , the adhesive was introduced into a drying zone and dried at 80°C for 5 seconds. did. Subsequently, a sealant film was bonded between rolls provided on the downstream side (roll pressure: 0.2 MP, roll temperature: 60°C). The obtained laminate was subjected to an aging treatment at 40° C. for 3 days in a wound state.
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 curing agent (CAT8B, manufactured by Toyo Morton Co., Ltd.), and 64.2% by mass of ethyl acetate. An ether adhesive was used, and the sealant film was an unstretched polypropylene film manufactured by Toyobo Co., Ltd. (Pylene (registered trademark) CT P1128, thickness 30 μm).
2) Measurement of laminate strength The laminate laminate obtained above was cut into strips (200 mm in length and 15 mm in width) with long sides in the longitudinal direction of biaxially oriented polypropylene film, and tested using a tensile tester (Tensilon, Orientech Co., Ltd.). The peel strength (N/15 mm) was measured using T-shaped peeling at a tensile speed of 200 mm/min in an environment of 23° C. The measurement was performed three times, and the average value was taken as the laminate strength.

(Example 1)
As the polypropylene resin, a propylene homopolymer (Japan Polypropylene Co., Ltd. ) "Novatec (registered trademark) PP SA4L" (copolymerization monomer amount: 0 mol %; hereinafter abbreviated as "PP-1") was used.
This polypropylene resin was extruded into a sheet from a T-die at 250°C using a 60mm uniaxial extruder, cooled and solidified using a cooling roll at 30°C, and heated to 135°C with a lengthwise (longitudinal direction) of 4.5 Stretched longitudinally by 8.2 times, then held at both ends with clips, introduced into a hot air oven, preheated at 170°C, stretched 8.2 times in the transverse direction (horizontal direction) at 160°C, and then stretched 6.7% Heat treatment was performed at 168° C. while applying relaxation. Thereafter, one side of the film was subjected to corona treatment and wound up with a winder to obtain a stretched polypropylene film to be used as the base material of the present invention.
The thickness of the obtained film was 20 μm. Table 1 shows the properties of the polypropylene constituting the film, and Table 2 shows the film forming conditions. The physical properties of the obtained film are as shown in Table 3, and the thermal shrinkage rate was low and the Young's modulus was high. Further, a chart obtained by differential scanning calorimetry (DSC) of this film is shown in FIG.
Particulate Al ₂ O ₃ (purity 99.5%) and SiO ₂ (purity 99.9%) with a size of about 3 to 5 mm were used as the evaporation source, and an electron beam evaporation method was used to deposit the above stretched polypropylene film. Al ₂ O ₃ and SiO ₂ were simultaneously vapor deposited to form an Al 2 O 3 -SiO 2 based thin film layer. As for the vapor deposition materials, a circular crucible with a diameter of 40 mm was divided into two by a carbon plate, and granular Al ₂ O ₃ and granular SiO ₂ were charged into each without mixing. Using one electron gun as a heating source _, each of Al2O3 and SiO2 is heated by time-sharing electron beam irradiation, heated and vaporized on the surface of the polypropylene film, and _Al2O3 and _SiO2 are mixed and deposited. Ta. At that time, the emission current of the electron gun was 205 mA, the accelerating voltage was 6 kV, and a power equivalent to 160 mA x 6 kV was applied to the aluminum oxide charged into the crucible, and a power equivalent to 45 mA x 6 kV was applied to the silicon oxide. The vacuum pressure during vapor deposition was 1.1×10 ⁻⁴ Pa, and the temperature of the roll supporting the film was 23° C. The thickness of the thin film layer was evaporated to 20 nm by changing the film forming speed using a crystal resonator type film thickness meter, and a laminated polypropylene film was obtained. Table 3 shows the physical properties of the obtained film.

(Example 2)
As the polypropylene resin, a propylene homopolymer (manufactured by Samsung Total Co., Ltd. HU300": copolymerization monomer amount is 0 mol%; hereinafter abbreviated as "PP-2"), the preheating temperature for transverse stretching was 171 ° C., the transverse stretching temperature was 161 ° C., and the heat treatment temperature after transverse stretching was 170 ° C. A stretched polypropylene film, which is the base material of the present invention, was obtained in the same manner as in Example 1 except that the following procedure was performed.
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 were as shown in Table 3.
In the same manner as in Example 1, an inorganic thin film layer was deposited on the stretched polypropylene film. Table 3 shows the physical properties of the obtained film.

(Example 3)
Low molecular weight propylene with a molecular weight of 10,000 (Hiwax "NP105" manufactured by Mitsui Chemicals, Inc.: copolymerization monomer amount is 0 mol %) with respect to 90 parts by mass of the propylene homopolymer (PP-1) used in Example 1. Add 10 parts by mass to make a total of 100 parts by mass, melt and knead in a 30 mm twin screw extruder, Mw / Mn = 11, Mz + 1 / Mn = 146, MFR = 7.0 g / 10 minutes, [mmmm] = Pellets of a 96.5% propylene polymer mixture (hereinafter abbreviated as "PP-3") were obtained. A stretched polypropylene film used for the base material of the present invention was obtained in the same manner as in Example 1, except that this pellet was used as the polypropylene resin.
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 were as shown in Table 3.
In the same manner as in Example 1, an inorganic thin film layer was deposited on the stretched polypropylene film. Table 3 shows the physical properties of the obtained film.

(Example 4)
A stretched polypropylene film used for the base material of the present invention was obtained in the same manner as in Example 3, except that it was stretched 5.5 times in the length direction and 12 times in the transverse direction.
The thickness of the obtained film was 20 μm. Table 1 shows the properties of the polypropylene constituting the film, and Table 2 shows the film forming conditions. The physical properties of the obtained film were as shown in Table 3.
In the same manner as in Example 1, an inorganic thin film layer was deposited on the stretched polypropylene film. Table 3 shows the physical properties of the obtained film.

(Example 5)
The stretched polypropylene film produced in Example 1 was held in a tenter at both ends in the film width direction with clips, and heat treated at 170° C. for 5 minutes to obtain the stretched polypropylene film of the present invention.
The thickness of the obtained film was 20 μm. Table 1 shows the properties of the polypropylene constituting the film, and Table 2 shows the film forming conditions. The physical properties of the obtained film were as shown in Table 3.
In the same manner as in Example 1, an inorganic thin film layer was deposited on the stretched polypropylene film. Table 3 shows the physical properties of the obtained film.

(Example 6)
As the polypropylene resin, a propylene homopolymer with Mw/Mn=4.0, Mz+1/Mn=23, MFR=6.0 g/10 min, [mmmm]=98.7% (comonomer amount is 0 mol) %; hereinafter abbreviated as "PP-4") was used in the same manner as in Example 1 to obtain a stretched polypropylene film for use in the base material of the present invention.
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 were as shown in Table 3.
In the same manner as in Example 1, an inorganic thin film layer was deposited on the stretched polypropylene film. Table 3 shows the physical properties of the obtained film.

(Example 7)
It is a laminated film (B layer/A layer/B layer) in which B layers are laminated on both sides of A layer. The A layer uses polypropylene homopolymer PP-4 shown in Table 1, and the The polypropylene homopolymer PP-8 shown in 1 was mixed with 0.15% by mass of silica as an anti-blocking agent. Lamination strength can be improved by laminating the B layer. Using a 60mm extruder for layer A and a 65mm extruder for layer B, extrude into a sheet from a T-die at 250°C, cool and solidify with a chill roll at 30°C, and then stretch 4.5 times in the longitudinal direction at 135°C. did. Next, in a tenter, both ends of the film in the width direction were held between clips, preheated at 170°C, stretched 8.2 times in the width direction at 160°C, and heat set at 168°C while relaxing by 6.7%. A biaxially stretched laminated polypropylene film in which one layer A and one layer B were laminated was obtained. The layer B side of the laminated polypropylene film was subjected to corona treatment and wound up with a winder. The thickness of the obtained film was 20 μm. Table 1 shows the structure of the polypropylene resin raw material, and Table 2 shows the film forming conditions. The physical properties of the obtained film are as shown in Table 3.
In the same manner as in Example 1, an inorganic thin film layer was deposited on the stretched polypropylene film. Table 3 shows the physical properties of the obtained film.

(Comparative example 1)
As the polypropylene resin, a propylene-ethylene copolymer (manufactured by Sumitomo Chemical Co., Ltd.) with Mw/Mn = 4, Mz + 1/Mn = 21, MFR = 2.5 g/10 min, [mmmm] = 97.0% was used. "Sumitomo Noblen (registered trademark) FS2011DG3": Copolymerized monomer amount is 0.6 mol%; hereinafter abbreviated as "PP-5"), the longitudinal stretching temperature was 125 ° C., the preheating temperature for transverse stretching was 168 ° C. A stretched polypropylene film was obtained in the same manner as in Example 1, except that the stretching temperature was 155°C and the heat treatment temperature after transverse stretching was 163°C.
The thickness of the obtained film was 20 μm. Table 1 shows the properties of the polypropylene constituting the film, and Table 2 shows the film forming conditions. The physical properties of the obtained film were as shown in Table 4.
In the same manner as in Example 1, an inorganic thin film layer was deposited on the stretched polypropylene film. Table 4 shows the physical properties of the obtained film.

(Comparative example 2)
A stretched polypropylene film was obtained in the same manner as in Comparative Example 1, except that the preheating temperature in transverse stretching was 171°C, the transverse stretching temperature was 160°C, and the heat treatment temperature after transverse stretching was 165°C.
The thickness of the obtained film was 20 μm. Table 1 shows the properties of the polypropylene constituting the film, and Table 2 shows the film forming conditions. The physical properties of the obtained film were as shown in Table 4.
In the same manner as in Example 1, an inorganic thin film layer was deposited on the stretched polypropylene film. Table 4 shows the physical properties of the obtained film.

(Comparative example 3)
As the polypropylene resin, a propylene homopolymer with Mw/Mn = 4.3, Mz + 1/Mn = 28, MFR = 0.5 g/10 min, [mmmm] = 97.0% (comonomer amount is 0 mol) A stretched polypropylene film was obtained in the same manner as in Comparative Example 2, except that %; hereinafter abbreviated as "PP-6") was used.
In the same manner as in Example 1, an inorganic thin film layer was deposited on the stretched polypropylene film. Table 4 shows the physical properties of the obtained film.
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 were as shown in Table 4.

(Comparative example 4)
As the polypropylene resin, a polypropylene polymer (Nippon Polypro Co., Ltd.) with Mw/Mn=2.8, Mz+1/Mn=9.2, MFR=30 g/10 min, [mmmm]=97.9% A stretched polypropylene film was obtained in the same manner as in Example 1, except that ``Novatec (registered trademark) PP SA03'' (copolymerized monomer amount was 0 mol%; hereinafter abbreviated as ``PP-7'') was used. However, the film broke during transverse stretching, and biaxial stretching was not possible. The reason for the breakage is that the orientation in the machine direction progresses during stretching in the machine direction, resulting in tearing during stretching in the vertical direction.

(Comparative example 5)
A stretched polypropylene film was obtained in the same manner as in Example 1, except that the longitudinal stretching temperature was 125°C, the preheating temperature for transverse stretching was 168°C, the transverse stretching temperature was 155°C, and the heat treatment temperature after transverse stretching was 163°C. Ta.
The thickness of the obtained film was 20 μm. Table 1 shows the properties of the polypropylene constituting the film, and Table 2 shows the film forming conditions. The physical properties of the obtained film were as shown in Table 4.
In the same manner as in Example 1, an inorganic thin film layer was deposited on the stretched polypropylene film. Table 4 shows the physical properties of the obtained film.

The laminated polypropylene film of the present invention can be widely used in packaging applications, industrial applications, etc., and since it has particularly excellent gas barrier properties, it can be made thinner, thereby reducing costs and weight. In addition, the laminated polypropylene film of the present invention has high heat resistance, so it can be processed at high temperatures during coating and printing, improving production efficiency and making it possible to use coating agents, inks, laminating adhesives, etc. that were difficult to use in the past. I can do it. Furthermore, the polypropylene film of the present invention is also suitable for insulating films for capacitors and motors, back sheets for solar cells, and base films for transparent conductive films such as ITO.

Claims (4)

A polypropylene system in which the lower limit of the mesopentad fraction measured by 13C-NMR is 96%, and the amount of components with a molecular weight of 100,000 or less when measuring a gel permeation chromatography (GPC) integration curve is 35% by mass or more. This is a laminated polypropylene film in which an inorganic thin film layer containing at least one of aluminum oxide and silicon oxide, or a composite oxide of these as the main component, is directly deposited on a biaxially stretched polypropylene film base material using a resin (however, if the inorganic thin film layer is (except when there are two or more layers),
The Young's modulus in the longitudinal direction of the biaxially oriented polypropylene film base material is 2 GPa or more, and the heat shrinkage rate in the longitudinal direction at 150°C of the biaxially oriented polypropylene film base material is 10% or less, and the The heat shrinkage rate in the direction is 15% or less, and the heat shrinkage rate in the longitudinal direction at 150 ° C. of the laminated polypropylene film is 7% or less,
A laminated polypropylene film having an oxygen permeability of 150 mL/m ² /day/MPa or less. The laminated polypropylene film according to claim 1, wherein the biaxially oriented polypropylene film base material has a transverse Young's modulus of 3.8 GPa or more. The laminated polypropylene film according to claim 1 or 2, wherein the laminated polypropylene film has a transverse heat shrinkage rate of 7% or less at 150°C. The laminated polypropylene film according to any one of claims 1 to 3.

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