WO2019172390A1

WO2019172390A1 - Biaxially stretched polypropylene film, metallized film, film capacitor and film roll

Info

Publication number: WO2019172390A1
Application number: PCT/JP2019/009166
Authority: WO
Inventors: 道子末葭; 剛史冨永; 立治石田; 忠和石渡
Original assignee: 王子ホールディングス株式会社
Priority date: 2018-03-07
Filing date: 2019-03-07
Publication date: 2019-09-12
Also published as: CN111801373A; JP7261389B2; JP2020041120A; CN111801373B; KR20200130245A

Abstract

A biaxially stretched polypropylene film which has a thickness of from 1.0 μm to 3.0 μm, and wherein: the difference between the thermal shrinkage ratio at 140°C in a first direction and the thermal shrinkage ratio at 130°C in the first direction is 0% or more but less than 2.0%; and the difference between the thermal shrinkage ratio at 140°C in a second direction that is perpendicular to the first direction and the thermal shrinkage ratio at 130°C in the second direction is 0% or more but less than 2.3%.

Description

Biaxially stretched polypropylene film, metallized film, film capacitor, and film roll

The present disclosure relates to a biaxially stretched polypropylene film, a metallized film, a film capacitor, and a film roll.

The biaxially stretched polypropylene film has excellent electrical characteristics such as high voltage resistance and low dielectric loss characteristics, and has high moisture resistance, and is therefore used as a dielectric for film capacitors.

1 and 2, the metallized film 5 constituting the film capacitor includes a biaxially stretched polypropylene film 10 and a metal layer 30 provided on the biaxially stretched polypropylene film 10. The metal layer 30 is provided on one surface of both surfaces of the biaxially stretched polypropylene film 10. 1 is a cross-sectional view taken along the line II in FIG.

As shown in FIG. 2, in the metallized film 5, an insulating margin 21 extending continuously in the longitudinal direction D1 is provided at one end 51 in the width direction D2. Usually, the insulation margin 21 is formed by covering a predetermined position of the biaxially stretched polypropylene film 10 with oil before metal deposition is performed on the biaxially stretched polypropylene film 10.

The metal layer 30 is located beside the insulation margin 21 (laterally in the width direction D2). The metal layer 30 extends from the other end 52 in the width direction D2 to the insulation margin 21. The area of the metal layer 30 is larger than that of the insulation margin 21.

At the end 52 of the metallized film 5, the thickness of the metal layer 30 is large. Such a portion 31 having a large thickness of the metal layer 30 may be referred to as a heavy edge portion. Hereinafter, the portion 31 is referred to as a heavy edge portion 31. The heavy edge portion 31 extends continuously in the longitudinal direction D1. The heavy edge portion 31 is provided in order to strengthen the bonding between the metallized film 5 and the metallicon electrode. On the other hand, in the metal layer 30, the portion 32 between the heavy edge portion 31 and the insulation margin 21 may be called an active portion. Hereinafter, the portion 32 is referred to as an active portion 32. The thickness of the active part 32 is smaller than that of the heavy edge part 31.

In order to produce such a metallized film 5, for example, a molten polypropylene resin is extruded into a sheet shape with a T-die to obtain a cast original fabric sheet, the cast original fabric sheet is biaxially stretched, and heat setting is performed. This is wound up to obtain a biaxially stretched polypropylene film, oil is attached to the biaxially stretched polypropylene film, and metal deposition is performed on this to produce a pre-slit metallized film 6 (see FIG. 3). .

As shown in FIG. 3, the pre-slit metallized film 6 includes a plurality of insulating margins 21 extending continuously in the longitudinal direction D1, and a metal layer 300 having a plurality of heavy edge portions 31 extending continuously in the longitudinal direction D1. . Thus, in the pre-slit metallized film 6, the insulation margins 21 and the metal layers 300 are alternately arranged in the width direction D2. Each metal layer 300 includes two active portions 32 and a heavy edge portion 31 located between the active portions 32. That is, in each metal layer 300, the first active portion 32, the heavy edge portion 31, and the second active portion 32 are arranged in this order in the width direction D2.

A cutting blade is inserted at the center in the width direction of each insulating margin 21 (center in the width direction D2) and the center in the width direction of each heavy edge portion 31 in the pre-slit metallized film 6, and the pre-slit metallized film 6 in the width direction D2. The metallized film 5 can be obtained by dividing it into a plurality of pieces (hereinafter referred to as “slit process”). If such a procedure is followed, the width of the insulating margin 21 in the metallized film 5 (the width in the width direction D2) becomes half of the width of the insulating margin 21 in the metallized film 6 before slitting. The width of the heavy edge portion 31 in the metallized film 5 (width in the width direction D2) is also half the width of the heavy edge portion 31 in the pre-slit metalized film 6. Here, the bar-shaped arrow shown in FIG. 3 indicates the position of the cutting blade and the cutting direction.

Japanese Patent Application Laid-Open No. 2015-195367

The metallized film obtained by such a procedure desirably has the same width of the insulation margin at one end in the longitudinal direction (for example, the slit start end) and the other end in the longitudinal direction (for example, the slit end end). This is because a metallized film whose insulation margin width differs greatly at one end and the other end may have an unintended effect on the film capacitor.

However, when the thickness of the biaxially stretched polypropylene film is 1.0 μm or more and 3.0 μm or less, in the metallized film after the slitting process, the width of the insulation margin at one end in the longitudinal direction and the other end in the longitudinal direction is Misalignment is likely to occur. This is because the heat shrinkage ratio increases as the thickness of the biaxially oriented polypropylene film decreases.

The purpose of the present disclosure is that the metallized film after the slit process in the metallized film after the biaxially stretched polypropylene film is thin and the width difference in the insulation margin between one end in the longitudinal direction and the other end in the longitudinal direction ( Hereinafter, it is to provide a biaxially stretched polypropylene film capable of suppressing “insulation margin width shift”.

The biaxially stretched polypropylene film of the first present disclosure (the biaxially stretched polypropylene film according to the first present invention) has a thickness of 1.0 μm to 3.0 μm and a heat shrinkage rate of 140 ° C. in the first direction. And the difference between the heat shrinkage rate at 130 ° C. in the first direction is not less than 0% and less than 2.0%, and the heat shrinkage rate at 140 ° C. in the second direction perpendicular to the first direction, The difference from the heat shrinkage rate at 130 ° C. in the second direction is 0% or more and less than 2.3%.
The biaxially stretched polypropylene film of the second present disclosure (the biaxially stretched polypropylene film according to the second present invention) has a thickness of 1.0 μm to 3.0 μm and a width in the second direction of 1200 mm or less. ,
A biaxially stretched polypropylene film obtained by the following methods (1) to (3), wherein the difference between the maximum value and the minimum value of the slow axis angle is less than 6 °.
<Determining the difference between the maximum and minimum values of the slow axis angle>
(1) When the total length in the width direction is 100%, a sample for measurement of 50 mm × 50 mm, centering on every 10% position from both ends, is cut out.
(2) The second direction of the measurement sample is 0 °, and the acute angle between the second direction of each measurement sample and the slow axis is measured,
(3) Among the nine measurement samples, the difference between the maximum and minimum angles measured in (2) is obtained.

From here, the background to which the present inventors have conceived the biaxially stretched polypropylene film of the present disclosure will be described.

<First Process and its Invention (First Invention)>
In the metallized film after the slitting process, the present inventor has intensively studied the cause of the shift in the width of the insulation margin between one end in the longitudinal direction and the other end in the longitudinal direction, and the cause is the oil for forming the insulation margin. The inventor initially thought that the temperature of the biaxially stretched polypropylene film was increased at the adhering location, and that the heat shrinkage was large at that location and that the heat shrinkage was small at the location where no oil was adhered. . The reason for this is that this oil is usually vaporized in order to adhere directly to the biaxially stretched polypropylene film, and adheres at about 130 ° C to 140 ° C.

Another cause of the deviation of the insulation margin width is that the metal vapor (for example, zinc vapor) for forming the heavy edge portion locally increases the temperature of the biaxially stretched polypropylene film, resulting in an in-plane temperature distribution and heat shrinkage. It was also considered that a large portion and a small portion were generated. The reason considered in this way is that the temperature of the metal vapor is high, for example, zinc vapor is about 600 ° C., so it can be considered that the thermal contraction is large at the portion where the metal vapor for forming the heavy edge portion is attached. There is.

However, considering the specific heat of the oil and the specific heat of the metal, the present inventor considered that the oil has a greater effect than the metal vapor on the local temperature rise in the biaxially stretched polypropylene film. Furthermore, in the process of attaching the metal vapor, the oil has a greater influence than the metal vapor because the surface opposite to the surface to which the metal vapor is attached of the biaxially stretched film is strongly cooled by the cooling roll. The inventor thought to give.

Therefore, in order to suppress the deviation of the insulation margin width, the heat shrinkage rate of 130 ° C. in the first direction and the heat of 130 ° C. in the second direction orthogonal to the first direction are referred with reference to the temperature of the oil for forming the insulation margin. The inventor has focused on reducing the shrinkage rate.

However, the present inventors have found that the insulation margin width deviation does not necessarily depend on the heat shrinkage rate of 130 ° C. in the first direction and the second direction.

More specifically, the insulation margin width shift is the difference between the heat shrinkage rate of 140 ° C. in the first direction and the heat shrinkage rate of 130 ° C. in the first direction, and the heat shrinkage rate of 140 ° C. in the second direction and the second The present inventor has found that it largely depends on the difference in heat shrinkage rate at 130 ° C. in the direction.

Based on these findings, the present inventor has come up with the biaxially stretched polypropylene film of the first present disclosure.

In the above configuration, the biaxially stretched polypropylene film is
And 140 ° C. thermal shrinkage _{S TD140} in the second direction, that the ratio _{_S} TD140 _/ _S _MD140 between the thermal shrinkage factor _{S MD140} of 140 ° C. in the first direction is 0.200 or more 0.325 or less preferable.

When the ratio S _TD140 / S _MD140 is within the above range, the in-plane heat shrinkage in the 140 ° C. region is well balanced (the heat shrinkage in the first direction and the second direction is balanced). It is more excellent in meat accuracy and can further suppress an insulation margin width shift.

In the above configuration, the biaxially stretched polypropylene film is
The width in the second direction is 1200 mm or less;
The difference between the maximum value and the minimum value of the slow axis angle obtained by the following methods (1) to (3) is preferably less than 6 °.
<Determining the difference between the maximum and minimum values of the slow axis angle>
(1) When the total length in the width direction is 100%, a sample for measurement of 50 mm × 50 mm, centering on every 10% position from both ends, is cut out.
(2) The second direction of the measurement sample is 0 °, and the acute angle between the second direction of each measurement sample and the slow axis is measured,
(3) Among the nine measurement samples, the difference between the maximum and minimum angles measured in (2) is obtained.

When the difference is less than 6 °, the thickness deviation accuracy of the biaxially stretched polypropylene film is more excellent. Moreover, when a metallized film is produced with the biaxially stretched polypropylene film, shrinkage unevenness in the in-plane direction is small, and wrinkles and talmi are suppressed, which can be suitably used.

Note that the biaxially stretched polypropylene film of the first present disclosure can be used for a capacitor.

Furthermore, the first present disclosure also relates to a metallized film, wherein the metallized film of the first present disclosure is formed on one or both sides of the biaxially stretched polypropylene film of the first present disclosure and the biaxially stretched polypropylene film. And a laminated metal layer.

The first present disclosure also relates to a film capacitor, wherein the film capacitor of the first present disclosure has the metallized film of the first present disclosure wound or the metallization of the first present disclosure. It can have a configuration in which a plurality of films are laminated.

The first present disclosure also relates to a film roll, and the film roll of the first present disclosure may be configured such that the biaxially stretched polypropylene film of the first present disclosure is wound in a roll shape. .

<Second Process and its Invention (Second Invention)>
The inventor examined the influence of oil in the same manner as the first process. In addition, the present inventor has focused on the slow axis angle of the biaxially stretched polypropylene film in order to suppress the insulation margin width shift. As a result, the present inventors have found that the insulation margin width deviation largely depends on the difference between the maximum value and the minimum value of the slow axis angle. Based on these findings, the present inventor has come up with the biaxially stretched polypropylene film of the second present disclosure.
In the above configuration, the biaxially stretched polypropylene film is
And 140 ° C. thermal shrinkage _{S TD140} in the second direction, that the ratio _{_S} TD140 _/ _S _MD140 between the thermal shrinkage factor _{S MD140} of 140 ° C. in the first direction is 0.200 or more 0.325 or less preferable. The reason is the same as in the case of the first invention.
In the above configuration, the biaxially stretched polypropylene film is
The difference between the heat shrinkage rate of 140 ° C. in the first direction and the heat shrinkage rate of 130 ° C. in the first direction is 0% or more and less than 2.0%, and the second direction perpendicular to the first direction It is preferable that the difference between the heat shrinkage rate at 140 ° C. and the heat shrinkage rate at 130 ° C. in the second direction is 0% or more and less than 2.3%.

The biaxially stretched polypropylene film of the second present disclosure can be used for a capacitor.

Further, the second present disclosure also relates to a metallized film, and the metallized film of the second present disclosure is formed on one or both sides of the biaxially stretched polypropylene film of the second present disclosure and the biaxially stretched polypropylene film. And a laminated metal layer.

The second present disclosure also relates to a film capacitor, and the film capacitor of the second present disclosure has a metallized film of the present disclosure wound or a plurality of metallized films of the second present disclosure. It can have a stacked configuration.

2nd this indication is related also with a film roll, The film roll of 2nd this indication can be set as the structure by which the biaxially stretched polypropylene film of 2nd this indication is wound by roll shape. .

The biaxially stretched polypropylene film of the present disclosure (the first present disclosure and the second present disclosure) is an insulating margin in the metallized film after the slitting process even though the biaxially stretched polypropylene film is thin. The width shift can be suppressed.

FIG. 3 is a cross-sectional view of a metallized film, and more specifically, a cross-sectional view taken along line II in FIG. It is a top view of a metallized film. It is a top view of the metallized film before a slit. It is a top view of the metallized film before a slit produced in the Example and the comparative example.

Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited only to these embodiments.
In this specification, the expressions “containing” and “including” include the concepts of “containing”, “including”, “consisting essentially of”, and “consisting only of”.
In this specification, the expression “capacitor” includes the concept of “capacitor”, “capacitor element”, and “film capacitor”.
Since the biaxially stretched polypropylene film of this embodiment is not a microporous film, it does not have a large number of pores.
The biaxially stretched polypropylene film of this embodiment may be composed of two or more layers, but is preferably composed of a single layer.
The biaxially stretched polypropylene film of the present embodiment achieves the above-described problem when the thickness is very small (thin) of 1.0 to 3.0 μm. The biaxially stretched polypropylene film of the present embodiment does not assume a case where the thickness is large (thick) such as 4.5 μm and 5 μm.

The two directions that appear in this embodiment will be described first. In the present embodiment, the first direction refers to the same direction as the longitudinal direction of the biaxially stretched polypropylene film. In the present embodiment, the first direction is also the same direction as Machine Direction (hereinafter referred to as “MD direction”). Hereinafter, the first direction is mainly referred to as the MD direction. However, the present invention is not limited to a form in which the first direction points to the same direction as the longitudinal direction, and is not limited to a form that points to the same direction as the MD direction. On the other hand, the second direction refers to the same direction as the width direction of the biaxially stretched polypropylene film. In the present embodiment, the second direction is also the same direction as Transverse Direction (hereinafter referred to as “TD direction”). Hereinafter, the second direction is mainly referred to as a TD direction. However, the present invention is not limited to a form in which the second direction points to the same direction as the width direction, and is not limited to a form that points to the same direction as the TD direction.

<Embodiment according to First Invention>
The thickness (thickness) of the biaxially stretched polypropylene film according to this embodiment is in the range of 1.0 to 3.0 μm. The thickness of the biaxially stretched polypropylene film according to this embodiment is preferably 1.2 μm or more, more preferably 1.5 μm or more, and further preferably 2.0 μm or more. Moreover, the thickness of the biaxially stretched polypropylene film according to this embodiment is preferably less than 3.0 μm, more preferably 2.9 μm or less, further preferably 2.8 μm or less, and particularly preferably 2.5 μm or less. In the case where the thickness of the biaxially stretched polypropylene film according to this embodiment is within the above ranges including the preferred range, the insulation margin width in the metallized film after the slit process despite the thin thickness of the biaxially stretched polypropylene film It is possible to obtain the excellent effect of suppressing the deviation to the maximum, and to obtain a film capacitor that is reduced in size and increased in capacity.
Further, since the polypropylene film has a thickness of 3.0 μm or less, the capacitance per unit volume when used as a capacitor element can be increased, so that it can be suitably used for a capacitor.
This point will be described in detail below.
The smaller the thickness of the polypropylene film, the larger the capacitance per unit volume. More specifically, the capacitance C is expressed as follows using the dielectric constant ε, the electrode area S, and the dielectric thickness d (the thickness d of the polypropylene film).
C = εS / d
Here, in the case of a film capacitor, the thickness of the electrode is three orders of magnitude thinner than the thickness of the polypropylene film (dielectric material). Therefore, when the volume of the electrode is ignored, the volume V of the capacitor is expressed as follows. Is done.
V = Sd
Therefore, the capacitance C / V per unit volume is expressed as follows from the above two formulas.
C / V = ε / d ²
As can be seen from the above formula, the capacitance per unit volume (C / V) is inversely proportional to the square of the thickness of the polypropylene film. The dielectric constant ε is determined by the material used. If it does so, unless the material is changed, it turns out that the electrostatic capacitance (C / V) per unit volume cannot be improved other than reducing thickness.
That is, assuming that a film capacitor is made of the same material, (1) When a film capacitor of the same size is made, a film capacitor having a larger capacity can be obtained by using a thin polypropylene film. Also, (2) when a film capacitor having the same capacity is produced, a smaller film capacitor can be obtained by using a thin polypropylene film, and space can be saved.

The thickness of the biaxially stretched polypropylene film refers to a value measured according to JIS-C2330 except that it was measured at 100 ± 10 kPa using a paper thickness measuring device MEI-11 manufactured by Citizen Seimitsu.

The biaxially stretched polypropylene film according to this embodiment has a difference between the heat shrinkage rate of 140 ° C. in the MD direction and the heat shrinkage rate of 130 ° C. in the MD direction (hereinafter referred to as “MD heat shrinkage rate difference”). % And less than 2.0%, and the difference between the heat shrinkage rate at 140 ° C. in the TD direction and the heat shrinkage rate at 130 ° C. in the TD direction (hereinafter referred to as “TD heat shrinkage rate difference”) is 0% or more. Less than 2.3%. In the present specification, the thermal shrinkage of 140 ° C. in the MD direction _{S MD140,} the thermal shrinkage of 130 ° C. in the MD direction heat shrinkage 140 ° C. in _{S MD130,} TD direction of 130 ° C. in _{S TD140,} TD direction The thermal contraction rate may be referred to as _STD130 . The MD thermal shrinkage rate difference herein _S MD140 _{-S MD130,} TD thermal shrinkage rate difference may be referred to as _S TD140 _{-S TD130.}

Although the biaxially stretched polypropylene film according to the present embodiment is thin in the range of 1.0 μm to 3.0 μm, in the metallized film after the slit process, one end in the longitudinal direction and the other end in the longitudinal direction Thus, the width shift in the insulation margin can be suppressed. Note that the width of the insulation margin is measured in the width direction of the biaxially stretched polypropylene film.

The reason why the deviation of the insulation margin width can be suppressed is estimated as follows.

First, when forming an insulation margin on a biaxially stretched polypropylene film, it is considered that the temperature unevenness occurs in the surface of each insulation margin due to the oil for forming the insulation margin.

It is considered that this temperature unevenness can be broadly classified into temperature unevenness in the TD direction and temperature unevenness in the MD direction.

In the temperature unevenness in the TD direction, it is considered that the temperature at the center portion in the TD direction is higher than the temperature at both end portions in the TD direction in each insulation margin. The reason is that the oil vapor for forming the insulation margin is ejected in a fan shape from the slit of the nozzle, so that the amount of oil at the center portion in the TD direction in the insulation margin is larger than that at both end portions in the TD direction. There is.

On the other hand, regarding the occurrence of temperature unevenness in the MD direction, although it is adjusted so that the oil vapor for forming the insulation margin is injected at a constant momentum, strictly speaking, it cannot be said that it is constant, and there is a slight fluctuation in momentum. Therefore, it is estimated that this variation causes temperature unevenness in the MD direction.

Furthermore, it is considered that the temperature range of temperature unevenness in each insulation margin plane is about 130 ° C. to 140 ° C. The reason for this is that oil vapor for forming an insulation margin is normally injected at about 130 ° C. to 140 ° C. Hereinafter, a region considered to be about 140 ° C. (region where the amount of oil is considered to be relatively large) may be referred to as a 140 ° C. region or a high temperature region, and a region considered to be about 130 ° C. The region considered to be relatively small) may be referred to as a 130 ° C. region.

It is considered that the biaxially stretched polypropylene film according to this embodiment can suppress wrinkles and sagging that would have conventionally occurred due to such temperature unevenness. This is thought to be due to the fact that the biaxially stretched polypropylene film according to the present embodiment has a heat shrinkage rate at 140 ° C. that would correspond to the temperature in the high temperature region of the insulation margin and the temperature in the 130 ° C. region of the insulation margin. The heat shrinkage rate at 130 ° C., which would correspond to the above, is close in two directions that form a right angle. In other words, when a temperature distribution occurs in each insulation margin with the oil for forming the insulation margin, a large distribution does not occur in the heat shrinkage rate at 130 ° C. and 140 ° C. of the biaxially stretched polypropylene film, that is, biaxial stretching. Since the heat shrinkage rate at 130 ° C. and the heat shrinkage rate at 140 ° C. of the polypropylene film are close, it is considered that wrinkles and sagging can be suppressed.

As a result of suppressing such wrinkles and sagging, it is presumed that the deviation of the insulation margin width can be suppressed by the biaxially stretched polypropylene film according to this embodiment.

TD direction 140 ° C. thermal shrinkage in the (second direction) and _{(S TD140),} MD direction ratio of thermal shrinkage of 140 ° C. in (first direction) _{(S MD140),} i.e. _{_S} TD140 _/ _S _MD140 is 0 200 or more is preferable, 0.240 or more is more preferable, 0.280 or more is further preferable, and 0.290 or more is particularly preferable. Further, S _TD140 / S _MD140 is preferably 0.385 or less, more preferably 0.360 or less, further preferably 0.330 or less, still more preferably 0.325 or less, particularly preferably 0.320 or less, 0 .315 or less is even more preferable. Further, S _TD140 / S _MD140 is preferably 0.200 or more and 0.385 or less, more preferably 0.240 or more and 0.360 or less, and more preferably 0.280 or more and 0.320 or less with respect to a range in which an upper limit and a lower limit are defined. Further preferred. When S _TD140 / S _MD140 is within the above range, in-plane heat shrinkage in the 140 ° C. region is well-balanced (the heat shrinkage in the TD direction and MD direction is balanced). It is excellent and the insulation margin width shift can be further suppressed.

Heat shrinkage of 130 ° C. in the TD direction _{(S TD130),} the ratio of the 130 ° C. thermal shrinkage in the MD direction _{(S MD130),} i.e. _{_S} TD130 _/ _S _MD130 is preferably 0.140 or less, 0.070 or more 0.130 or less is more preferable, and 0.080 or more and 0.100 or less is more preferable. When S _TD130 / S _MD130 is within the above range, in-plane heat shrinkage in the 130 ° C. region is well-balanced (the heat shrinkage in the TD direction and MD direction is balanced). It is excellent and the insulation margin width shift can be further suppressed.

Ratio of TD heat shrinkage rate difference (S _TD140 -S _TD130 ) and MD heat shrinkage rate difference (S _MD140 -S _MD130 ), that is, (S _TD140 -S _TD130 ) / (S _MD140 -S _MD130 ) is 0.920 or more 1.350 or less is preferable, 0.930 or more and 1.200 or less are preferable, and 0.960 or more and 1.080 or less are more preferable. When (S _TD140 -S _TD130 ) / (S _MD140 -S _MD130 ) is within the above range, the in-plane thermal shrinkage in the 130 to 140 ° C. region is well balanced (equal thermal shrinkage in the TD and MD directions). Therefore, the thickness accuracy is excellent and the insulation margin width deviation can be further suppressed.

Both the MD heat shrinkage difference (S _MD140 -S _MD130 ) and the TD heat shrinkage difference (S _TD140 -S _TD130 ) are the speed of the take-up roll that winds the biaxially stretched polypropylene film downstream of the tenter ( (Hereinafter referred to as “take-off speed”) and the MD-direction polypropylene film transport speed (hereinafter referred to as “film-forming line speed”) in the tenter stretching section and also affected by the heat setting temperature. . These will be described in detail when describing biaxial stretching.

The difference in MD heat shrinkage (S _MD140 −S _MD130 ) is preferably 0.1% or more, more preferably 0.5% or more, further preferably 1.0% or more, and particularly preferably 1.5% or more. The difference in MD heat shrinkage is preferably 1.9% or less, and more preferably 1.8% or less.

On the other hand, the TD heat shrinkage difference (S _TD140 -S _TD130 ) is preferably 0.1% or more, more preferably 0.5% or more, further preferably 1.0% or more, and particularly preferably 1.5% or more. . The TD heat shrinkage difference is preferably 2.2% or less, more preferably 2.0 or less, further preferably 1.9% or less, and particularly preferably 1.8% or less.

The heat shrinkage rate (S _MD140 ) at 140 ° C. in the MD direction is preferably 10.0% or less, more preferably 9.0% or less, and even more preferably 8.5% or less. The heat shrinkage rate (S _MD140 ) at 140 ° C. in the MD direction is preferably 1.0% or more, more preferably 3.0% or more, further preferably 5.0% or more, and particularly preferably 7.0% or more.

The heat shrinkage rate (S _TD140 ) at 140 ° C. in the TD direction is preferably 5.0% or less, more preferably 4.0% or less, still more preferably 3.5% or less, and particularly preferably 2. 7% or less. The thermal shrinkage rate at 140 ° C. in the TD direction is preferably 0.1% or more, more preferably 0.5% or more, further preferably 1.0% or more, and particularly preferably 2.0% or more.

The width in the TD direction (second direction) of the biaxially stretched polypropylene film is not particularly limited. However, when the difference between the maximum value and the minimum value of the slow axis angle obtained by the following methods (1) to (3) is less than 6 °, the width in the TD direction (second direction) is 1200 mm or less. It is preferable.

That is, the biaxially stretched polypropylene film is
The width in the TD direction (second direction) is 1200 mm or less,
The difference between the maximum value and the minimum value of the slow axis angle obtained by the following methods (1) to (3) is preferably less than 6 °. This point will be described below.
Here, the slow axis will be described.
The biaxially stretched polypropylene film according to this embodiment is stretched in the first direction and in the second direction perpendicular to the first direction. Since the polymer is oriented in-plane by the biaxial stretching, the biaxially stretched film has birefringence. In the film plane, the direction in which the refractive index is maximum is called a slow axis because the direction in which light travels is slow (the phase is delayed).
For example, in the sequential biaxial stretching method, first, the original cast sheet is stretched in the flow direction (MD direction), and then the sheet is stretched in the transverse direction (TD direction). In this case, with respect to the slow axis of the biaxially stretched polypropylene film, the lateral refractive index in the second direction tends to be larger than the refractive index in the flow direction in the first direction. Here, the horizontal direction of the second direction is the slow axis.
In the stretching in the transverse direction (TD direction), when the stretching is performed completely in the transverse direction (when the stretching is performed completely in the direction perpendicular to the flow direction), the slow phase defined in this specification is used. The shaft angle is 0 °. However, in practice, Poisson contraction stress, mechanical external force, film thermoplasticity, etc. act upon stretching, and the film cannot be completely stretched in the transverse direction (TD direction), and the slow axis angle is from 0 °. Tend to be larger. In the sequential biaxial stretching method, the slow axis angle tends to increase toward both ends of the biaxially stretched film.
In the present embodiment, the smaller the difference between the maximum value and the minimum value of the slow axis angle, the relative to two orthogonal directions of the first flow direction (MD direction) and the second horizontal direction (TD direction). It can be said that the deviation of the optical alignment axis is small. Therefore, when producing a metallized film, the shrinkage in the oblique direction during heating is reduced, and the thermal shrinkage in the first direction and the second direction can be easily balanced. As a result, wrinkles and talmi during processing are suppressed, and the film can be suitably used. Furthermore, when the film is stretched, the thickness of the obtained film is excellent because the film is deformed in the transverse direction (TD direction) in which stretching stress acts.
Also, as the maximum value of the slow axis angle is smaller, it is difficult to apply a deformation force in an oblique direction different from the transverse direction (TD direction) when forming a biaxially stretched polypropylene film, so that stretch breakage is reduced and continuous production is reduced. It tends to be excellent in film properties. In particular, since the biaxially stretched polypropylene film of the present embodiment has a very small (thin) thickness of 1.0 to 3.0 μm, the effect is remarkable.
The difference between the maximum value and the minimum value of the slow axis angle according to the present embodiment is not anisotropy of the optical orientation strength indicated by birefringence or the like, that is, not the orientation size and direction itself, but the second direction. And the angle between the maximum value and the minimum value of the slow axis, that is, the fluctuation range in the width direction of the slow axis angle. In the present embodiment, it is preferable to control the difference to be small.
The reason why it is preferable to control the difference to be small is that even if a flexible material such as polypropylene is given orientation strength by biaxial stretching to give a certain machining strength, thermal dimensional change that occurs during metal deposition processing. The amount is not sufficiently reduced, but rather it is clear from the result that suppressing the displacement and fluctuation in the orientation direction is useful for suppressing the shrinkage unevenness in the in-plane direction.
Furthermore, the polypropylene film of this embodiment has a very small (thin) characteristic of 1.0 to 3.0 μm, and is greatly affected by the temperature of metal deposition processing. For this reason, the orientation of the orientation is also important along with the thermal contraction rate. In the present embodiment, by reducing the fluctuation range in the width direction of the slow axis angle, the thermal shrinkage orientation can be maintained.
<Determining the difference between the maximum and minimum values of the slow axis angle>
(1) When the total length in the width direction is 100%, a sample for measurement of 50 mm × 50 mm, centered on the position every 10% from both ends, is cut out.
(2) The second direction of the measurement sample is 0 °, and the acute angle between the second direction of each measurement sample and the slow axis is measured,
(3) Among the nine measurement samples, the difference between the maximum and minimum angles measured in (2) is obtained.

The difference between the maximum value and the minimum value of the slow axis angle is preferably less than 6 °, more preferably 5.5 ° or less, further preferably 5 ° or less, and particularly preferably 4.5 ° or less. When the difference is less than 6 °, the thickness deviation accuracy of the biaxially stretched polypropylene film is more excellent. Moreover, when a metallized film is produced with the biaxially stretched polypropylene film, shrinkage unevenness in the in-plane direction is small, and wrinkles and talmi are suppressed, which can be suitably used.

The maximum value of the slow axis angle is preferably less than 15 °, more preferably 14.5 ° or less, further preferably 13 ° or less, and particularly preferably 12 ° or less. When the maximum value is within the numerical range, the biaxially stretched polypropylene film tends to have few breaks and excellent continuous productivity.

When the difference between the maximum value and the minimum value of the slow axis angle is less than 6 °, the width in the TD direction (second direction) is preferably 1200 mm or less, more preferably 1100 mm or less, and 1000 mm or less. More preferably. Moreover, when the said difference is less than 6 degrees, the width | variety of TD direction (2nd direction) can be 500 mm or more, 550 mm or more, 600 mm or more, etc.

The measurement apparatus and measurement conditions for obtaining the difference between the maximum value and the minimum value of the slow axis angle are as follows.
<Measurement equipment and measurement conditions>
Measuring device: retardation measuring device RE-100 manufactured by Otsuka Electronics Co., Ltd.
Light source: Laser light emitting diode (LED)
Bandpass filter: 550 nm (measurement wavelength)
Measurement interval: 0.1 sec
Integration count: 10time
Number of measurement points: 15 points
Gain: 10dB
Measurement environment: temperature 23 ° C, humidity 60%

The difference between the maximum value and the minimum value of the slow axis angle tends to increase as the heat setting temperature decreases, and tends to increase as the ratio of the take-up speed to the film forming line speed increases.
The maximum value of the slow axis angle tends to increase as the heat setting temperature decreases, and tends to increase as the ratio of the take-up speed to the film forming line speed increases.

The biaxially stretched polypropylene film and the metallized film are each wound in a roll shape, and are preferably in the form of a film roll. The film roll may or may not have a winding core (core). The film roll preferably has a winding core (core). The material of the winding core of the film roll is not particularly limited. Examples of the material include paper (paper tube), resin, fiber reinforced plastic (FRP), metal, and the like. Examples of the resin include polyvinyl chloride, polyethylene, polypropylene, phenol resin, epoxy resin, acrylonitrile-butadiene-styrene copolymer, and the like. Examples of the plastic constituting the fiber reinforced plastic include polyester resin, epoxy resin, vinyl ester resin, phenol resin, and thermoplastic resin. Examples of the fibers constituting the fiber reinforced plastic include glass fibers, aramid fibers (Kevlar (registered trademark) fibers), carbon fibers, polyparaphenylene benzoxazole fibers (Zylon (registered trademark) fibers), polyethylene fibers, and boron fibers. Can be mentioned. Examples of the metal include iron, aluminum, and stainless steel. The core of the film roll also includes a core formed by impregnating a paper tube with the resin. In this case, the material of the winding core is classified as a resin.

Next, the suitable raw material and manufacturing method of the biaxially stretched polypropylene film according to this embodiment will be described below. However, the raw material and manufacturing method of the biaxially stretched polypropylene film according to this embodiment are not limited to the following descriptions.

The biaxially stretched polypropylene film contains a polypropylene resin. The content of the polypropylene resin is preferably 75% by mass or more, more preferably 90% by mass or more, based on the entire biaxially stretched polypropylene film (when the entire biaxially stretched polypropylene film is 100% by mass). More preferably, it is 95 mass% or more. The upper limit of the content of the polypropylene resin is, for example, 100% by mass or 98% by mass with respect to the entire biaxially stretched polypropylene film. The polypropylene resin and the biaxially stretched polypropylene film according to this embodiment may include a single type of polypropylene resin alone or may include two or more types of polypropylene resins.

The weight average molecular weight Mw of the polypropylene resin is preferably from 280,000 to 450,000, and more preferably from 280,000 to 400,000. When the weight average molecular weight Mw of the polypropylene resin is 280,000 or more and 450,000 or less, the resin fluidity becomes appropriate. As a result, it is easy to control the thickness of the cast raw sheet, and it becomes easy to produce a thin stretched film.

The molecular weight distribution (Mw / Mn) of the polypropylene resin is preferably 5 or more, more preferably 6.1 or more, still more preferably 6.5 or more, still more preferably 7.2 or more, and 7.5 or more. Is particularly preferred. The molecular weight distribution of the polypropylene resin is preferably 12 or less, more preferably 11 or less, further preferably 10 or less, and particularly preferably 9.5 or less. It is preferably 5 or more and 12 or less, more preferably 5 or more and 11 or less, and further preferably 5 or more and 10 or less with respect to a range that defines the upper limit and the lower limit of the molecular weight distribution of the polypropylene resin.

In this specification, the weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of a polypropylene resin are values measured using a gel permeation chromatograph (GPC) apparatus. . More specifically, it is a value measured using an HLC-8121 GPC-HT (trade name), a high-temperature GPC measuring machine with a built-in differential refractometer (RI) manufactured by Tosoh Corporation. As GPC columns, three TSKgel GMHHR-H (20) HT manufactured by Tosoh Corporation are connected and used. The column temperature is set to 140 ° C., and trichlorobenzene is allowed to flow as an eluent at a flow rate of 1.0 ml / 10 minutes to obtain measured values of Mw and Mn. A calibration curve related to the molecular weight M is prepared using standard polystyrene manufactured by Tosoh Corporation, and the measured values are converted into polystyrene values to obtain Mw and Mn. Here, the logarithm of the bottom 10 of the molecular weight M of standard polystyrene is referred to as logarithmic molecular weight (“Log (M)”).

Differential distribution value difference _{D M} of the polypropylene resin is preferably at -5% to 14% or less, more preferably 12% or less -4% or more, still be 10% less than -4% preferable. Here, the “differential distribution value difference D _M ” is a differential distribution value when Log (M) = 6.0 from a differential distribution value when the logarithmic molecular weight Log (M) = 4.5 in the molecular weight differential distribution curve. The difference minus.
“The differential distribution value difference _DM is −5% or more and 14% or less” means that the component having a molecular weight of 10,000 to 100,000 on the lower molecular weight side than the Mw value of the polypropylene resin (hereinafter referred to as “low A component having a logarithmic molecular weight Log (M) = 4.5 as a typical distribution value of a molecular weight component) and a component having a molecular weight of about 1 million on the high molecular weight side (hereinafter also referred to as “high molecular weight component”). When comparing the components with Log (M) = 6.0, which is a typical distribution value, if the difference is positive, there are more low molecular weight components, and if the difference is negative, the higher molecular weight components. It can be understood that there are many.

In other words, even though the molecular weight distribution Mw / Mn is 5 to 12, it merely represents the breadth of the molecular weight distribution width, and the quantitative relationship between the high molecular weight component and the low molecular weight component therein is unknown. Absent. Therefore, from the viewpoint of stable film forming properties and thickness uniformity of the cast raw sheet, the polypropylene resin has a wide molecular weight distribution and at the same time has a molecular weight of 10,000 to 100,000 in order to appropriately contain a low molecular weight component. It is preferable to use a polypropylene resin so that the component has a differential distribution value difference of -5% or more and 14% or less compared to a component having a molecular weight of 1,000,000.

The differential distribution value is a value obtained as follows using GPC. A curve (generally also referred to as “elution curve”) showing the intensity with respect to time obtained by a differential refraction (RI) detector of GPC is used. Using the calibration curve obtained with standard polystyrene, the elution curve is converted into a curve showing the intensity with respect to Log (M) by converting the time axis into logarithmic molecular weight (Log (M)). Since the RI detection intensity is proportional to the component concentration, an integral distribution curve with respect to the logarithmic molecular weight Log (M) can be obtained when the total area of the curve indicating the intensity is 100%. The differential distribution curve is obtained by differentiating the integral distribution curve with Log (M). Therefore, “differential distribution” means a differential distribution with respect to the molecular weight of the concentration fraction. From this curve, the differential distribution value at a specific Log (M) is read.

The mesopentad fraction ([mmmm]) of the polypropylene resin is preferably 94% or more, more preferably 95% or more, further preferably more than 95%, particularly preferably more than 95.5%, particularly more preferably more than 96%. preferable. The mesopentad fraction of the polypropylene resin is preferably 98.5% or less, more preferably 98.4% or less, still more preferably 98% or less, particularly preferably less than 98.0%, and 97.5% or less. Particularly preferred, 97.0% or less is particularly preferred. The mesopentad fraction of the polypropylene resin is preferably 94% or more and 99% or less, and more preferably 95% or more and 98.5% or less. By using such a polypropylene resin, the crystallinity of the resin is moderately improved by the reasonably high stereoregularity, and the initial voltage resistance and the voltage resistance over a long period are improved. On the other hand, desired stretchability can be obtained by an appropriate solidification (crystallization) rate when the cast raw sheet is formed.

The mesopentad fraction ([mmmm]) is an index of stereoregularity that can be obtained by high temperature nuclear magnetic resonance (NMR) measurement. Specifically, it can be measured using, for example, JEOL Ltd., high temperature Fourier transform nuclear magnetic resonance apparatus (high temperature FT-NMR), JNM-ECP500. The observation nucleus is 13C (125 MHz), the measurement temperature is 135 ° C., and the solvent for dissolving the polypropylene resin is ortho-dichlorobenzene (ODCB: ODCB and deuterated ODCB mixed solvent (mixing ratio = 4/1). The measurement method by high temperature NMR is, for example, the method described in “Japan Analytical Chemistry / Polymer Analysis Research Roundtable, New Edition, Polymer Analysis Handbook, Kinokuniya, 1995, p. 610”. Can be done with reference.

The measurement mode is single pulse proton broadband decoupling, the pulse width is 9.1 μsec (45 ° pulse), the pulse interval is 5.5 sec, the number of integration is 4500 times, and the shift reference is CH ₃ (mmmm) = 21.7 ppm. be able to.
The pentad fraction representing the degree of stereoregularity is a combination of the quintet (pentad) of the consensus “meso (m)” arranged in the same direction and the consensus “rasemo (r)” arranged in the opposite direction (mmmm and mrrm). Etc.) based on the integrated value of the intensity of each signal derived from. Each signal derived from mmmm, mrrm and the like can be assigned with reference to, for example, “T. Hayashi et al., Polymer, 29, 138 (1988)”.

The heptane insoluble content (HI) of the polypropylene resin is preferably 96.0% or more, more preferably 97.0% or more. Further, the heptane insoluble content (HI) of the polypropylene resin is preferably 99.5% or less, more preferably 99.0% or less. Here, the heptane-insoluble content indicates that the greater the stereoregularity of the resin, the greater the amount. When the heptane-insoluble content (HI) is 96.0% or more and 99.5% or less, the crystallinity of the resin is moderately improved due to the reasonably high stereoregularity, and the voltage resistance at high temperature is improved. . On the other hand, the rate of solidification (crystallization) at the time of forming the cast original fabric sheet becomes moderate, and it has moderate stretchability.

The melt flow rate (MFR) of the polypropylene resin is preferably 1.0 to 8.0 g / 10 min, more preferably 1.5 to 7.0 g / 10 min, and 2.0 to 6.0 g / min. More preferably, it is 10 minutes.

Polypropylene resin can be generally produced using a known polymerization method. Examples of the polymerization method include a gas phase polymerization method, a bulk polymerization method, and a slurry polymerization method. On the other hand, as a polypropylene resin, it is of course possible to use a commercially available product.

It is preferable that the total ash due to the polymerization catalyst residue contained in the polypropylene raw resin or in the biaxially stretched polypropylene film of the present embodiment is as small as possible in order to improve the electrical characteristics. The total ash content is preferably 50 ppm or less, more preferably 40 ppm or less, and particularly preferably 30 ppm or less, based on the polypropylene resin (100 parts by weight).

The polypropylene resin may contain an additive. Examples of the additive include an antioxidant, a chlorine absorbent, an ultraviolet absorbent, a lubricant, a plasticizer, a flame retardant, and an antistatic agent. The polypropylene resin may contain additives in an amount that does not adversely affect the biaxially oriented polypropylene film.

For a while from here, each polypropylene resin when using two or more kinds of polypropylene resins will be described.

When two or more kinds of polypropylene resins are used, the following linear polypropylene resin A-1 and the following linear polypropylene resin B-1, the following linear polypropylene resin A-2, the following linear polypropylene resin B-2, and the following linear polypropylene Preferred examples include resin A-3 and the following linear polypropylene resin B-3, or a combination of the following linear polypropylene resin A-4 and the following linear polypropylene resin B-4. In the present embodiment, the expression linear polypropylene resin A includes the concept of linear polypropylene resin A-1, linear polypropylene resin A-2, linear polypropylene resin A-3, and linear polypropylene resin A-4. The expression linear polypropylene resin B includes the concept of linear polypropylene resin B-1, linear polypropylene resin B-2, linear polypropylene resin B-3, and linear polypropylene resin B-4. However, in the present invention, the polypropylene resin is not limited to the following resins.
<Linear polypropylene resin A>
(Linear polypropylene resin A-1)
A linear polypropylene resin having a differential distribution value difference _DM of 8.0% or more.
(Linear polypropylene resin A-2)
A linear polypropylene resin having a heptane-insoluble content (HI) of 98.5% or less.
(Linear polypropylene resin A-3)
A linear polypropylene resin having a melt flow rate (MFR) at 230 ° C. of 4.0 to 10.0 g / 10 min.
(Linear polypropylene resin A-4)
A linear polypropylene resin having a weight average molecular weight Mw of 280,000 to 340,000.
<Linear polypropylene resin B>
(Linear polypropylene resin B-1)
Linear polypropylene differential distribution value difference _{D M} is less than 8.0%.
(Linear polypropylene resin B-2)
A linear polypropylene resin having a heptane insoluble content (HI) exceeding 98.5%.
(Linear polypropylene resin B-3)
A linear polypropylene resin having a melt flow rate (MFR) at 230 ° C. of 0.1 to 3.9 g / 10 min.
(Linear polypropylene resin B-4)
A linear polypropylene resin having a weight average molecular weight Mw of more than 340,000.

The weight average molecular weight Mw of the linear polypropylene resin A is preferably 280,000 or more. Further, the weight average molecular weight Mw of the linear polypropylene resin A is preferably 450,000 or less, more preferably 400,000 or less, further preferably 350,000 or less, and 340,000 or less. Is particularly preferred. When the weight average molecular weight Mw of the linear polypropylene resin A is 280,000 or more and 450,000 or less, the resin fluidity becomes appropriate. As a result, it is easy to control the thickness of the cast original fabric sheet, and it becomes easy to produce a thin biaxially stretched polypropylene film. In addition, the thickness of the cast original fabric sheet and the biaxially stretched polypropylene film is less likely to cause unevenness, and an appropriate stretchability is obtained.

The molecular weight distribution Mw / Mn of the linear polypropylene resin A is preferably 8.5 or more and 12.0 or less, more preferably 8.5 or more and 11.0 or less, and 9.0 or more and 11.0 or less. More preferably.

It is preferable that the molecular weight distribution Mw / Mn of the linear polypropylene resin A is within the above-mentioned preferable range because unevenness is less likely to occur in the thicknesses of the cast raw sheet and the biaxially stretched polypropylene film, and appropriate stretchability is obtained.

Differential distribution value difference _{D M} of linear polypropylene resin A is preferably at least 8.0%, more preferably 8.0% or more and 18.0% or less, at least 9.0% 17.0 percent or less More preferably, it is more preferably 10.0% or more and 16.0% or less.

Differential distribution value difference _{D M} is, if 18.0% or less 8.0% or more, the low molecular weight component, rich in a ratio of when compared to high molecular weight components, 18.0% 8.0% inclusive. Therefore, the surface of the biaxially stretched polypropylene film in this embodiment can be easily obtained, which is preferable.

The mesopentad fraction ([mmmm]) of the linear polypropylene resin A is preferably 99.8% or less, more preferably 99.5% or less, and further preferably 99.0% or less. preferable. The mesopentad fraction is preferably 94.0% or more, more preferably 94.5% or more, and further preferably 95.0% or more. When the mesopentad fraction is within the above numerical range, the crystallinity of the resin is moderately improved due to the reasonably high stereoregularity, and the voltage resistance at high temperatures is improved. On the other hand, the rate of solidification (crystallization) during molding of the cast sheet is moderate, and it has moderate stretchability.

The heptane insoluble content (HI) of the linear polypropylene resin A is preferably 96.0% or more, more preferably 97.0% or more. Further, the heptane-insoluble content (HI) of the linear polypropylene resin A is preferably 99.5% or less, more preferably 98.5% or less, and further preferably 98.0% or less.

The melt flow rate (MFR) at 230 ° C. of the linear polypropylene resin A is preferably 1.0 to 15.0 g / 10 min, more preferably 2.0 to 10.0 g / 10 min. 0 to 10.0 g / 10 min is more preferable, and 4.3 to 6.0 g / 10 min is particularly preferable. When the MFR at 230 ° C. of the linear polypropylene resin A is within the above range, the flow characteristics in the melted state are excellent, so that unstable flow such as melt fracture does not easily occur, and breakage during stretching can be suppressed. Therefore, since the film thickness uniformity is good, there is an advantage that the formation of a thin portion where dielectric breakdown is likely to occur is suppressed.

The content of the linear polypropylene resin A is preferably 55% by mass or more, and more preferably 60% by mass or more with respect to the entire biaxially stretched polypropylene film. The content of the linear polypropylene resin A is preferably 99.9% by mass or less, more preferably 90% by mass or less, and 100% by mass with respect to 100% by mass of the entire polypropylene resin in the polypropylene film. % Or less is more preferable, and 80% by mass or less is particularly preferable.

The weight average molecular weight Mw of the linear polypropylene resin B is preferably 300,000 or more, more preferably 330,000 or more, further preferably more than 3340, and even more preferably 350,000 or more. Preferably, it is more preferably 350,000. Moreover, it is preferable that the weight average molecular weight Mw of the linear polypropylene resin B is 400,000 or less, and it is more preferable that it is 380,000 or less.

The molecular weight distribution Mw / Mn of the linear polypropylene resin B is preferably 6.0 or more and less than 8.5, more preferably 6.5 or more and 8.4 or less, and 7.0 or more and 8.3 or less. More preferably, it is 7.2 or more and 8.2 or less.

It is preferable that the molecular weight distribution Mw / Mn of the linear polypropylene resin B is within the above-mentioned preferable range because unevenness is hardly generated in the thickness of the cast raw sheet and the biaxially stretched polypropylene film, and appropriate stretchability is obtained.

Differential distribution value difference _{D M} of linear polypropylene resin B is preferably less than 8.0%, more preferably less than 8.0% or more -20.0%, or more -10.0% 7 It is more preferably 9% or less, and particularly preferably −5.0% or more and 7.5% or less.

The mesopentad fraction ([mmmm]) of the linear polypropylene resin B is preferably less than 99.8%, more preferably 99.5% or less, and further preferably 99.0% or less. preferable. The mesopentad fraction is preferably 94.0% or more, more preferably 94.5% or more, and further preferably 95.0% or more. When the mesopentad fraction is within the above numerical range, the crystallinity of the resin is moderately improved due to the reasonably high stereoregularity, and the voltage resistance at high temperatures is improved. On the other hand, the rate of solidification (crystallization) during molding of the cast sheet is moderate, and it has moderate stretchability.

The heptane-insoluble content (HI) of the linear polypropylene resin B is preferably 97.5% or more, more preferably 98% or more, still more preferably 98.5%, and particularly preferably 98.%. 6% or more. Further, the heptane-insoluble content (HI) of the linear polypropylene resin B is preferably 99.5% or less, more preferably 99% or less.

The melt flow rate (MFR) at 230 ° C. of the linear polypropylene resin B is preferably 0.1 to 6.0 g / 10 min, more preferably 0.1 to 5.0 g / 10 min, and More preferably, it is 1 to 3.9 g / 10 min.

When the linear polypropylene resin B is used as the polypropylene resin, the content of the linear polypropylene resin B is preferably 10% by mass or more when the entire polypropylene resin in the polypropylene film is 100% by mass, It is more preferably 15% by mass or more, and further preferably 20% by mass or more. Similarly, the content of the linear polypropylene resin B is preferably 45% by mass or less and more preferably 40% by mass or less, assuming that the total polypropylene resin in the polypropylene film is 100% by mass. .

When the linear polypropylene resin A and the linear polypropylene resin B are used in combination as the polypropylene resin, if the total polypropylene resin is 100% by mass, 55 to 90% by weight of the linear polypropylene resin A and 45 to 10% by weight of the polypropylene resin are used. The linear polypropylene resin B is preferably included, more preferably 60 to 85% by weight of the linear polypropylene resin A and 40 to 15% by weight of the linear polypropylene resin B, and more preferably 60 to 80% by weight of the linear polypropylene resin B. It is particularly preferable that the chain polypropylene resin A and 40 to 20% by weight of the linear polypropylene resin B are included.

When the polypropylene resin includes a linear polypropylene resin A and a linear polypropylene resin B, the biaxially stretched polypropylene film is in a finely mixed state (phase separated state) of the linear polypropylene resin A and the linear polypropylene resin B. Therefore, the voltage resistance (particularly body voltage at a high temperature) is improved, and the capacity of the film capacitor element is improved.

The above description is an explanation of each polypropylene resin when two or more polypropylene resins are used.

The biaxially stretched polypropylene film may contain a resin other than the polypropylene resin (hereinafter also referred to as “other resin”). Other resins include polyolefins other than polypropylene such as polyethylene, poly (1-butene), polyisobutene, poly (1-pentene), poly (1-methylpentene); ethylene-propylene copolymer, propylene-butene copolymer Copolymers, copolymers of α-olefins such as ethylene-butene copolymer; vinyl monomers-diene monomer random copolymer such as styrene-butadiene random copolymer; styrene-butadiene-styrene block copolymer Examples thereof include vinyl monomers such as coalescence-diene monomer-vinyl monomer random copolymer. The biaxially stretched polypropylene film may contain such other resin in an amount that does not adversely affect the biaxially stretched polypropylene film. The biaxially stretched polypropylene film of this embodiment is preferably composed of a polypropylene resin as a resin.

The cast original sheet before stretching for producing a biaxially stretched polypropylene film can be produced as follows.

First, polypropylene resin pellets, dry-mixed polypropylene resin pellets, or mixed polypropylene resin pellets prepared by melting and kneading in advance are supplied to an extruder and melted by heating.
The rotation speed of the extruder during heating and melting is preferably 5 to 40 rpm, and more preferably 10 to 30 rpm. Further, the set temperature of the extruder at the time of heating and melting is preferably 220 to 280 ° C, and more preferably 230 to 270 ° C. The resin temperature at the time of heating and melting is preferably 220 to 280 ° C., more preferably 230 to 270 ° C. The resin temperature at the time of heating and melting is a value measured by a thermometer inserted in an extruder.
Note that the number of revolutions of the extruder, the set temperature of the extruder, and the resin temperature during heating and melting are selected in consideration of the physical properties of the crystalline thermoplastic resin to be used. In addition, deterioration of resin can also be suppressed by making the resin temperature at the time of heat-melting in such a numerical range.

Next, the molten resin is extruded into a sheet shape using a T die, and cooled and solidified with at least one metal drum to form an unstretched cast raw sheet.
The surface temperature of the metal drum (the temperature of the metal drum that first comes into contact after extrusion) is preferably 50 to 100 ° C., more preferably 90 to 100 ° C. The surface temperature of the metal drum can be determined according to the physical properties of the polypropylene resin used.

The biaxially stretched polypropylene film can be produced by subjecting a cast raw sheet to stretching treatment. The stretching is preferably biaxial stretching that is biaxially oriented longitudinally and laterally, and the sequential biaxial stretching method is preferred as the stretching method. As the sequential biaxial stretching method, for example, first, the cast original fabric sheet is passed between rolls provided with a speed difference and stretched 3 to 7 times in the flow direction (MD direction). Subsequently, the sheet is guided to a tenter and stretched 3 to 11 times in the transverse direction (TD direction). The temperature during stretching in the flow direction (also referred to as longitudinal stretching temperature) is preferably 130 to 150 ° C. Further, the temperature during stretching in the width direction (also referred to as transverse stretching temperature) is preferably 155 to 170 ° C. Thereafter, relaxation and heat fixation are performed, and the product is wound around a take-up roll. As described above, a biaxially stretched polypropylene film is obtained.

As described above, the difference between the MD heat shrinkage ratio and the TD heat shrinkage ratio of the biaxially stretched polypropylene film is the speed of the take-up roll that winds the biaxially stretched polypropylene film downstream of the tenter (take-off speed). And in the tenter stretching part, it is influenced by the transport speed (film forming line speed) of the polypropylene film in the MD direction. Further, the difference between the maximum value and the minimum value of the slow axis angle and the maximum value of the slow axis angle are affected by the take-up speed and the film forming line speed. Therefore, the ratio of the take-up speed to the film-formation line speed (take-off speed / film-formation line speed) will be described. This ratio is preferably 1.01 or more and 1.20 or less, more preferably 1.02 or more and 1.18 or less, further preferably 1.03 or more and 1.15 or less, and particularly preferably 1.05 to 1.09. is there. By adjusting this ratio to 1.20 or less, it is possible to keep the tension of the biaxially stretched polypropylene film just above the take-up roll so as not to bend, and to keep the thermal dimensional deformation suitably small. Can do. The reason why the thermal dimensional deformation can be suppressed is considered to be because the progress of the orientation of the polymer molecular chain can be suppressed. By adjusting this ratio to 1.20 or less, it is possible to suitably suppress breakage of the polypropylene film after biaxial stretching immediately above the take-up roll. When the ratio of the take-up speed to the film- _formation line speed (take-up speed / film- _formation line speed) is increased (increased), _SMD140- _SMD130 , _STD140- _STD130 , and _STD140 / _SMD140 all tend to increase. When the ratio is lowered (lowered), S _MD140 -S _MD130 , S _TD140 -S _TD130 , and S _TD140 / S _MD140 tend to decrease.

Both the MD heat shrinkage difference and the TD heat shrinkage difference are affected not only by the ratio of the take-up speed to the film forming line speed, but also by the heat setting temperature in heat setting after biaxial stretching. Further, the difference between the maximum value and the minimum value of the slow axis angle and the maximum value of the slow axis angle are affected by the heat setting temperature. Therefore, the heat setting temperature will be described. The present inventor believes that the phenomenon that the mobility of the polymer molecular chain changes depending on the temperature affects the temperature dependency of the thermal shrinkage rate. That is, since the mobility of the polymer molecular chain with respect to the temperature change is considered to change depending on the heat setting temperature, the present invention is affected by both the MD heat shrinkage difference and the TD heat shrinkage difference. Guesses. The heat setting temperature is preferably 159 ° C. or higher and 169 ° C. or lower, more preferably 161 ° C. or higher and 167 ° C. or lower, still more preferably 162 ° C. or higher and 166 ° C. or lower, and particularly preferably 162 ° C. or higher and 164 ° C. or lower. 169 ° C. or less is preferable because the difference in MD heat shrinkage rate is less than 2.0% and the difference in TD heat shrinkage rate is less than 2.3%. In order to prevent the polypropylene film after biaxial stretching from being broken immediately above the take-up roll and to form a film with good thickness deviation accuracy, 169 ° C. or lower is preferable. Here, the uneven thickness accuracy refers to the degree of thickness uniformity in the TD direction in a biaxially stretched polypropylene film. When the heat setting temperature in the heat setting after biaxial stretching is increased (increased), S _MD140 -S _MD130 , S _TD140 -S _TD130 , and S _TD140 / S _MD140 tend to decrease, and the heat setting temperature is increased. When lowered (lowered), all of S _MD140 -S _MD130 , S _TD140 -S _TD130 , and S _TD140 / S _MD140 tend to rise.

In this way, the polypropylene film after biaxial stretching is heat-set at 159 ° C. or more and 169 ° C. or less, and is further wound up at a ratio of the take-up speed to the film forming line speed of 1.01 or more and 1.20 or less. Preferably, the MD heat shrinkage difference can be less than 2.0% and the TD heat shrinkage difference can be less than 2.3%.

The biaxially stretched polypropylene film may be subjected to corona discharge treatment on-line or off-line after the end of the stretching and heat setting steps for the purpose of enhancing the adhesive properties in the subsequent steps such as a metal deposition process. The corona discharge treatment can be performed using a known method. It is preferable to use air, carbon dioxide gas, nitrogen gas, or a mixed gas thereof as the atmospheric gas.

オイル Apply oil of a pattern corresponding to the pattern of the insulation margin on one side of the biaxially stretched polypropylene film to form an oil mask for the insulation margin, and perform metal deposition on this to obtain a pre-slit metallized film. The oil mask for insulation margin is for preventing metal particles from adhering to the portion that becomes the insulation margin of the biaxially stretched polypropylene film in the vapor deposition process. The oil mask for the insulation margin can be formed by evaporating the oil stored in the oil tank and directly applying the oil to the biaxially stretched polypropylene film from a nozzle provided in the tank. Here, “direct application” means that the oil is blown out from the slit of the nozzle, and this oil is adhered to the biaxially oriented polypropylene film. On the other hand, the metal deposition is performed when the biaxially stretched polypropylene film after the formation of the oil mask for the insulation margin passes through the cooling roll. The cooling roll is maintained at −30 ° C. to −20 ° C., for example. That is, metal vapor deposition is performed when a biaxially stretched polypropylene film having an insulating margin oil mask passes through a space between a cooling roll and a metal vapor deposition source. Thus, in this space, metal vapor is emitted toward the surface of the biaxially stretched polypropylene film on which the insulation margin oil mask is formed, and adheres to the biaxially stretched polypropylene film. The cooling roll is used to prevent the biaxially stretched polypropylene film from being deformed by the heat of the metal vapor. Examples of metals used in metal deposition include simple metals such as zinc, lead, silver, chromium, aluminum, copper, and nickel, mixtures of these, and alloys thereof, but the environment, economy, and film In consideration of capacitor performance and the like, it is preferable to use aluminum for the active portion and zinc and aluminum for the heavy edge portion. Such a metal layer is formed by, for example, depositing aluminum on both a region where an active portion is to be formed and a region where a heavy edge portion is to be formed in a biaxially stretched polypropylene film having an oil mask for an insulation margin. Further, it can be formed by further vapor-depositing zinc in a region where the heavy edge portion is to be formed. Alternatively, for example, aluminum may be deposited only in a region where the active part is to be formed, and zinc may be deposited only in a region where the heavy edge part is to be formed. In the case where a margin pattern is provided in the active portion, the oil mask for pattern is formed between the formation of the oil mask for the insulation margin and the metal deposition, that is, after the formation of the oil mask for the insulation margin and before the metal deposition. Of the both sides of the film, the film can be formed on the surface on which the insulating margin oil mask is formed. The pattern oil mask is usually formed by a plate roll. The oil temperature for forming the pattern oil mask is lower than that for forming the insulation margin oil mask. The oil for forming the pattern oil mask is applied to a biaxially oriented polypropylene film, for example, at room temperature (40 ° C. or lower as an example).

The pre-slit metallized film thus obtained and the metallized film obtained by dividing the pre-slit metallized film will now be described with reference to the drawings.

As shown in FIG. 3, the pre-slit metallized film 6 includes a plurality of insulating margins 21 extending continuously in the MD direction D1 and a metal layer 300 extending continuously in the MD direction D1. In the pre-slit metallized film 6, the insulation margins 21 and the metal layers 300 are alternately arranged in the TD direction D2. Each metal layer 300 includes two active portions 32 and a heavy edge portion 31 located between the active portions 32. That is, in each metal layer 300, the first active portion 32, the heavy edge portion 31, and the second active portion 32 are arranged in this order in the TD direction D2. As described above, the first active portion 32 extends in the TD direction D2 from one end of the heavy edge portion 31 in the TD direction D2, and the second active portion extends from the other end of the heavy edge portion 31 in the TD direction D2. 32 extends in the TD direction D2. The first and second active portions 32 extend continuously in the MD direction D1. The heavy edge portion 31 also extends continuously in the MD direction D1. In the example shown in FIG. 3, although the insulation margins 21 are provided at both ends in the TD direction D2 in the pre-slit metallized film 6, the heavy edge portions 31 are provided at both ends or one of the both ends. It may be done.

In the slit process of the pre-slit metallized film 6, a cutting blade is provided at the center in the TD direction D <b> 2 in each insulation margin 21 (hereinafter sometimes referred to as “TD direction center”) and the center in the TD direction of each heavy edge portion 31. The pre-slit metallized film 6 is divided into a plurality of portions in the TD direction D2 to obtain a metallized film 5 (see FIGS. 1 and 2). Specifically, the pre-slit metallized film 6 in the form of a roll is unwound, a cutting blade is inserted into the center of each insulation margin 21 in the TD direction and the center of each heavy edge 31 in the TD direction, and the metallized film is cut. 5 is rolled up. Thereby, a plurality of metallized films 5 can be obtained. The width of the insulating margin 21 in the metallized film 5 is half the width of the insulating margin 21 in the pre-slit metalized film 6. The width of the heavy edge portion 31 in the metallized film 5 is also half the width of the heavy edge portion 31 in the pre-slit metalized film 6. The metallized film 5 has a capacitor element width.

As shown in FIGS. 1 and 2, the metallized film 5 thus obtained includes a biaxially stretched polypropylene film 10 and a metal layer 30 provided on one side of the biaxially stretched polypropylene film 10. The thickness of the metal layer 30 is preferably within 1 to 200 nm.

In the metallized film 5, an insulating margin 21 extending continuously in the MD direction D1 is provided at one end 51 in the TD direction D2. The length of the insulation margin 21 is larger than the width of the insulation margin 21.

The metal layer 30 is located beside the insulation margin 21 in the TD direction D2. The metal layer 30 extends from the other end 52 in the TD direction D2 to the insulation margin 21. Although not shown, the metal layer 30 continuously extends between both ends of the metallized film 5 in the MD direction D1. That is, the metal layer 30 continuously extends from one end portion of the metallized film 5 in the MD direction D1 to the other end portion of the metallized film 5 in the MD direction D1. The width of the metal layer 30 is larger than the width of the insulating margin 21. For example, the width of the metal layer 30 is preferably 1.5 to 300 times the width of the insulation margin 21. Here, the width of the metal layer 30 is a value measured by ignoring the margin pattern. The width of the metal layer 30 is measured in the TD direction D2 of the metallized film 5.

The metal layer 30 of the metallized film 5 includes a heavy edge portion 31. The heavy edge part 31 is located in the end part 52 of the metallized film 5 in the TD direction D2. The heavy edge portion 31 extends continuously in the MD direction D1. More specifically, the heavy edge portion 31 continuously extends between both ends of the metallized film 5 in the MD direction D1. That is, the heavy edge portion 31 continuously extends from one end portion of the metallized film 5 in the MD direction D1 to the other end portion of the metallized film 5 in the MD direction D1. The thickness of the heavy edge portion 31 is larger than the thickness of the active portion 32. The heavy edge part 31 can have, for example, an aluminum film provided on the biaxially stretched polypropylene film 10 and a zinc part provided on the aluminum film. Thus, in the heavy edge part 31, an aluminum film can be located between the biaxially stretched polypropylene film 10 and the zinc part.

The metal layer 30 of the metallized film 5 includes an active portion 32. The active part 32 extends continuously in the MD direction D1. More specifically, the active part 32 extends continuously between both ends of the metallized film 5 in the MD direction D1. That is, the active portion 32 continuously extends from one end portion of the metallized film 5 in the MD direction D1 to the other end portion of the metallized film 5 in the MD direction D1. The active part 32 can have an aluminum film. The aluminum film of the active part 32 is continuous with the aluminum film of the heavy edge part 31. The active portion 32 may be formed with a margin pattern, such as a T margin pattern. The film resistance of the heavy edge portion 31 is usually about 1 to 8Ω / □, and preferably about 1 to 5Ω / □.

The metallized film 5 can be laminated by a conventionally known method or wound to form a film capacitor. For example, a pair of metallized films 5 so that the metal layers 30 and the biaxially stretched polypropylene films 10 in the metallized film 5 are alternately laminated, and further the insulation margin 21 is on the opposite side. And roll them together. At this time, it is preferable that two pairs of metallized films 5 are laminated while being shifted by 1 to 2 mm in the TD direction D2. The winding machine to be used is not particularly limited. For example, an automatic winder 3KAW-N2 manufactured by Minato Seisakusho Co., Ltd. can be used. When producing a flat capacitor, after winding, the obtained wound product is usually pressed. Press to facilitate film capacitor winding and capacitor element molding. From the viewpoint of controlling / stabilizing the interlayer gap, the optimum value of the applied pressure varies depending on the thickness of the biaxially stretched polypropylene film 10 and the like, but is, for example, 2 to 20 kg / cm ² . Subsequent to pressing, metal capacitors are sprayed on both end faces of the wound material to provide a metallicon electrode, thereby producing a film capacitor.

Thus, the film capacitor may have a configuration in which a plurality of metallized films 5 are laminated, or may have a wound metallized film 5. Such a film capacitor can be suitably used as a capacitor for an inverter power supply device that controls a drive motor of an electric vehicle or a hybrid vehicle. Further, it can be suitably used for railway vehicles, wind power generation, solar power generation, general household appliances, and the like.

Although FIGS. 1 to 3 illustrate the metallized film 5 in which the metal layer 30 is provided on one side of the biaxially stretched polypropylene film 10, the metallized film of the present invention is limited to the metallized film 5 having such a structure. Of course you can't. For example, the metallized film of the present invention may be provided with metal layers on both sides of a biaxially stretched polypropylene film.

In this embodiment, although the metallized film having the heavy edge portion has been described, it is needless to say that the metallized film does not have to have the heavy edge portion.

<Embodiment according to Second Invention>
The second embodiment of the present invention will be described below. In the biaxially stretched polypropylene film according to the second embodiment of the present invention, the difference between the heat shrinkage rate at 140 ° C. in the first direction and the heat shrinkage rate at 130 ° C. in the first direction is 0% or more. The difference between the heat shrinkage rate at 140 ° C. in the second direction perpendicular to the first direction and the heat shrinkage rate at 130 ° C. in the second direction is not less than 0% 2. It need not be less than 3%.
The polypropylene film according to the second embodiment of the present invention (hereinafter also referred to as “second embodiment”) has a thickness of 1.0 μm to 3.0 μm and a width in the second direction of 1200 mm or less. A biaxially oriented polypropylene film having a difference between the maximum value and the minimum value of the slow axis angle of less than 6 ° obtained by the following methods (1) to (3).
<Determining the difference between the maximum and minimum values of the slow axis angle>
(1) When the total length in the width direction is 100%, a sample for measurement of 50 mm × 50 mm, centering on every 10% position from both ends, is cut out.
(2) The second direction of the measurement sample is 0 °, and the acute angle between the second direction of each measurement sample and the slow axis is measured,
(3) Among the nine measurement samples, the difference between the maximum and minimum angles measured in (2) is obtained. The biaxially stretched polypropylene film according to the second embodiment of the present invention is excellent in uneven thickness accuracy. Moreover, when a metallized film is produced with the biaxially stretched polypropylene film, shrinkage unevenness in the in-plane direction is small, and wrinkles and talmi are suppressed.
In the above configuration, the biaxially stretched polypropylene film has a difference between a heat shrinkage rate of 140 ° C. in the first direction and a heat shrinkage rate of 130 ° C. in the first direction of 0% or more and less than 2.0%, The difference between the heat shrinkage rate of 140 ° C. in the second direction perpendicular to the first direction and the heat shrinkage rate of 130 ° C. in the second direction is preferably 0% or more and less than 2.3%. Regarding other preferable heat shrinkage rates of the biaxially stretched polypropylene film according to the present embodiment, and the difference between the heat shrinkage rates and the ratio of the heat shrinkage rates, refer to the “embodiment according to the first invention”. This is the same as described in the section. Therefore, description is abbreviate | omitted here. In the second embodiment according to the present invention, it is added here that the section “Embodiment according to the first present invention” can be cited for grounds for correction, technical explanation, and the like.
The preferable aspect of the biaxially stretched polypropylene film according to the present embodiment is the same as that of the “embodiment according to the first aspect of the present invention”. For example, in the biaxially stretched polypropylene film according to this embodiment, (1) each film physical property (for example, thickness, total ash content, etc.), (2) the type, physical property, ratio, combination, etc. ) Types other than the polypropylene resin included, physical properties, proportions, combinations, etc. (4) For the production method of the biaxially stretched polypropylene film according to the present embodiment, etc. This is the same as the description in the section “form”. Further, (5) each physical property and configuration of the metallized film according to the present embodiment, and production method thereof, and (6) each physical property, configuration and production method thereof of the film capacitor, respectively, “first This is the same as the description in the section “Embodiment according to the present invention”. Therefore, description is abbreviate | omitted here. In the second embodiment according to the present invention, it is added here that the section “Embodiment according to the first present invention” can be cited for grounds for correction, technical explanation, and the like.

Next, the present invention (the first invention and the second invention) will be described more specifically with reference to examples. However, these examples are for explaining the present invention. It is not limited at all. Unless otherwise specified, “part” and “%” in the examples represent “part by mass” and “% by mass”, respectively.

<Measurement of Weight Average Molecular Weight (Mw), Molecular Weight Distribution (Mw / Mn), and Differential Distribution Value of Polypropylene Resin>
Using GPC (gel permeation chromatography), the measurement was performed under the following conditions.
Measuring instrument: manufactured by Tosoh Corporation, differential refractometer (RI) built-in high temperature GPC HLC-8121GPC / HT type column: manufactured by Tosoh Corporation, three TSKgel GMHhr-H (20) HT, connected column temperature: 145 ° C
Eluent: Trichlorobenzene Flow rate: 1.0 ml / min
A calibration curve was prepared using standard polystyrene manufactured by Tosoh Corporation, and the measured molecular weight value was converted to a polystyrene value to obtain a weight average molecular weight (Mw) and a number average molecular weight (Mn). A molecular weight distribution (Mw / Mn) was obtained using the values of Mw and Mn.
The differential distribution value was obtained by the following method. First, a time curve (elution curve) of an intensity distribution detected using an RI detector is converted into a distribution curve with respect to the molecular weight M (Log (M)) of standard polystyrene using a calibration curve prepared using the standard polystyrene. Converted. Next, after obtaining an integral distribution curve for Log (M) when the total area of the distribution curve is 100%, the differential distribution for Log (M) is obtained by differentiating the integral distribution curve with Log (M). I was able to get a curve. From this differential distribution curve, differential distribution values when Log (M) = 4.5 and Log (M) = 6.0 were read. A series of operations until obtaining the differential distribution curve was performed using analysis software built in the GPC measurement apparatus used.

<Mesopentad fraction>
Polypropylene resin was dissolved in a solvent and measured using a high-temperature Fourier transform nuclear magnetic resonance apparatus (high-temperature FT-NMR) under the following conditions.
High-temperature nuclear magnetic resonance (NMR) apparatus: JEOL Ltd., high-temperature Fourier transform nuclear magnetic resonance apparatus (high-temperature FT-NMR), JNM-ECP500
Observation nucleus: ¹³ C (125 MHz)
Measurement temperature: 135 ° C
Solvent: ortho-dichlorobenzene (ODCB: mixed solvent of ODCB and deuterated ODCB (mixing ratio = 4/1))
Measurement mode: Single pulse proton broadband decoupling pulse width: 9.1 μsec (45 ° pulse)
Pulse interval: 5.5 sec
Integration count: 4,500 shift standard: CH ₃ (mmmm) = 21.7 ppm
The pentad fraction representing the degree of stereoregularity is a combination of a quintet (pentad) of a consensus “meso (m)” arranged in the same direction and a consensus “rasemo (r)” arranged in the same direction (mmmm or mrrm). Etc.) was calculated as a percentage (%) from the integrated intensity of each signal. Regarding the attribution of each signal derived from mmmm, mrrm, etc., for example, the description of spectra such as “T. Hayashi et al., Polymer, 29, 138 (1988)” was referred to.

<Measurement of melt flow rate (MFR)>
For each resin, the melt flow rate (MFR) in the form of raw material resin pellets was measured according to the condition M of JIS K 7210 using a melt indexer manufactured by Toyo Seiki Co., Ltd. Specifically, first, a sample weighed to 4 g was inserted into a cylinder set at a test temperature of 230 ° C., and preheated for 3.5 minutes under a load of 2.16 kg. Thereafter, the weight of the sample extruded from the bottom hole in 30 seconds was measured to obtain MFR (g / 10 min). The above measurement was repeated three times, and the average value was taken as the MFR measurement value.

<Measurement of heptane insoluble matter (HI)>
Each resin was press-molded to 10 mm × 35 mm × 0.3 mm to prepare a measurement sample of about 3 g. Next, about 150 mL of heptane was added and Soxhlet extraction was performed for 8 hours. The heptane-insoluble content was calculated from the sample mass before and after extraction.

<Example 1>
[Preparation of cast sheet]
PP resin A1 [Mw = 320,000, Mw / Mn = 9.3, differential distribution value difference D _M = 11.2, mesopentad fraction [mmmm] = 95%, HI = 97.3%, MFR = 4.9 g / 10 min, made of prime polymer] and PP resin B1 [Mw = 350,000, Mw / Mn = 7.7, differential distribution value difference D _M = 7.2, mesopentad fraction [mmmm] = 96.5%, HI = 98.6%, MFR = 3.8 g / 10 min, manufactured by Korea Oil Chemical Co., Ltd.], and fed to the extruder at a ratio of 65:35, melted at a resin temperature of 250 ° C., and then extruded using a T-die. It was wound around a metal drum maintained at a surface temperature of 95 ° C. and solidified to produce a cast original fabric sheet.
[Production of biaxially oriented polypropylene film]
The obtained cast sheet was kept at a temperature of 140 ° C., passed between rolls provided with a speed difference, stretched 4.5 times in the flow direction, and immediately cooled to room temperature. Subsequently, the stretched film was guided to a tenter, stretched 10 times in the width direction at 160 ° C., then relaxed and heat-set, and a 2.3 μm thick biaxially stretched polypropylene film was wound around a take-out roll at the exit of the tenter. I took it. The heat setting temperature during the heat setting was 164 ° C. The speed of the take-up roll was 1.09 times the film forming line speed. That is, the ratio of the take-up speed to the film-formation line speed (take-up speed / film-formation line speed) was 1.09.
[Preparation of pre-slit metallized film]
The biaxially stretched polypropylene film was unwound from a roll to form an insulation margin oil mask on the biaxially stretched polypropylene film. Next, a pattern oil mask having a pattern corresponding to the electrode pattern was formed on the biaxially stretched polypropylene film on which the insulation margin oil mask was formed. Next, metal vapor deposition was performed on the biaxially stretched polypropylene film on which the pattern oil mask was formed. This obtained the metallized film before a slit.
Here, in order to form an oil mask for an insulation margin, fomblin oil vapor was sprayed onto one surface of both surfaces of the biaxially stretched polypropylene film with a nozzle slit. The oil mask for insulation margin was formed in a striped shape (striped shape) on the entire surface of the biaxially stretched polypropylene film (see FIG. 4).
The pattern oil mask was formed by a plate roll. The pattern oil mask was formed in a pattern substantially corresponding to the electrode pattern of the metal vapor deposition electrode in the region where the striped insulation margin oil mask was not formed on the entire surface of the biaxially stretched polypropylene film.
In metal deposition, aluminum was first deposited. The vapor deposition of aluminum is performed on the entire surface of the biaxially stretched polypropylene film on which the insulation margin oil mask and the pattern oil mask are formed (hereinafter referred to as “oil mask formation surface”). It was. Subsequently, zinc was vapor-deposited in order to form a heavy edge part. Zinc was vapor-deposited aiming at a region where a heavy edge portion was to be formed on the oil mask forming surface. Metal vapor deposition, that is, aluminum vapor deposition and zinc vapor deposition, was performed while cooling the biaxially oriented polypropylene film with a cooling roll maintained at −30 ° C. to −20 ° C. That is, when the biaxially stretched polypropylene film was passed through the space between the cooling roll and the evaporation source for metal deposition, aluminum was deposited and then zinc was deposited.
The pre-slit metallized film thus obtained will be described with reference to FIG. As shown in FIG. 4, the pre-slit metallized film (pre-slit metallized film 6) includes three insulating margins 21 that continuously extend in the MD direction D1, and two metal layers 300 that extend continuously in the MD direction D1. It was included. Each insulation margin 21 extends continuously from one end in the MD direction D1 of the pre-slit metallized film 6 to the other end in the MD direction D1 of the pre-slit metallized film 6. Each metal layer 300 also extends continuously from one end in the MD direction D1 in the pre-slit metallized film 6 to the other end in the MD direction D1 in the pre-slit metallized film 6. In the pre-slit metallized film 6, the insulation margins 21 and the metal layers 300 are alternately arranged in the TD direction D2. Each metal layer 300 includes two active portions 32 and a heavy edge portion 31 located between the active portions 32. That is, in each metal layer 300, the first active portion 32, the heavy edge portion 31, and the second active portion 32 are arranged in this order in the TD direction D2. The first and second active portions 32 extend continuously in the MD direction D1. The heavy edge portion 31 also extends continuously in the MD direction D1.
When evaluating the margin accuracy of the pre-slit metallized film 6, a cutting blade was inserted into the insulating margin 21 located at the center in the TD direction D2 among the three insulating margins 21, and the insulating margin width was measured.

<Example 2>
A biaxially stretched polypropylene film and a pre-slit metallized film prepared thereby were obtained in the same manner as in Example 1 except that the thickness of the biaxially stretched polypropylene film was 2.4 μm.

<Example 3>
A biaxially stretched polypropylene film and a pre-slit metallized film prepared in this manner were obtained in the same manner as in Example 1 except that the thickness of the biaxially stretched polypropylene film was 2.5 μm.

<Example 4>
A biaxially stretched polypropylene film and a pre-slit metallized film thus prepared were obtained in the same manner as in Example 1 except that the thickness of the biaxially stretched polypropylene film was 2.8 μm.

<Example 5>
Biaxially stretched polypropylene film and pre-slit metallized film prepared in the same manner as in Example 1 except that the heat setting temperature was 162 ° C. and the speed of the take-up roll was 1.05 times the film forming line speed. And got.

<Example 6>
Biaxially stretched polypropylene film and pre-slit metallized film prepared in the same manner as in Example 4 except that the heat setting temperature was 166 ° C. and the speed of the take-up roll was 1.15 times the film forming line speed. And got.

<Example 7>
Biaxially stretched polypropylene film and pre-slit metallized film prepared in the same manner as in Example 1 except that the heat setting temperature was 161 ° C. and the speed of the take-up roll was 1.02 times the film forming line speed. And got.

<Example 8>
Instead of polypropylene resin B1, polypropylene resin B2 (Mw = 380,000, Mw / Mn = 8.3, D _M = 0.6, mesopentad fraction [mmmm] = 96.7%, HI = 98.8%, MFR = 2.3 g / 10 min, manufactured by Korea Oil Chemical Co., Ltd.) was used in the same manner as in Example 1 to prepare a cast raw sheet. A biaxially stretched polypropylene film and a pre-slit metallized film made of this biaxially stretched polypropylene film were obtained in the same manner as in Example 1 except that this cast raw sheet was used.

<Example 9>
Biaxially stretched polypropylene film and pre-slit metallized film prepared in the same manner as in Example 4 except that the heat setting temperature was 166 ° C. and the speed of the take-up roll was 1.12 times the film forming line speed. Got.

<Comparative Example 1>
Biaxially stretched polypropylene film and pre-slit metallized film prepared in the same manner as in Example 3 except that the heat setting temperature was 158 ° C. and the speed of the take-up roll was 1.10 times the film forming line speed. And got.

<Comparative example 2>
A biaxially stretched polypropylene film and a pre-slit metallized film prepared in the same manner as in Example 1 except that the heat setting temperature was 160 ° C. and the speed of the take-up roll was 1.21 times the film forming line speed. And got.

<Comparative Example 3>
Biaxially stretched polypropylene film and pre-slit metallized film prepared in the same manner as in Example 4 except that the heat setting temperature was 160 ° C. and the speed of the take-up roll was 1.21 times the film forming line speed. And got.

<Comparative example 4>
Biaxially stretched polypropylene film and pre-slit metallized film prepared in the same manner as in Example 8 except that the heat setting temperature was 160 ° C. and the speed of the take-up roll was 1.21 times the film forming line speed. And got.

<Comparative Example 5>
A biaxially stretched polypropylene film and a pre-slit metallized film prepared in the same manner as in Example 1 except that the heat setting temperature was 170 ° C. and the speed of the take-up roll was 1.22 times the film forming line speed. And got.
<Comparative Example 6>
Polypropylene resin A2 (Mw = 270,000, Mw / Mn = 5.7, D _M = 8.8, HI = 97.8%, MFR = 5.6 g / 10 min) was used instead of polypropylene resin A1. Instead of B1, polypropylene resin B2 (Mw = 380,000, Mw / Mn = 8.3, D _M = 0.6, mesopentad fraction [mmmm] = 96.7%, HI = 98.8%, MFR = 2 .3 g / 10 min, manufactured by Korea Oil Chemical Co., Ltd.) was used in the same manner as in Example 1 to prepare a cast raw sheet. A biaxially stretched polypropylene film and a pre-slit metallized film made of this biaxially stretched polypropylene film were obtained in the same manner as in Example 1 except that this cast raw sheet was used.

<Thickness measurement>
The thickness of the biaxially stretched polypropylene film was measured according to JIS-C2330 except that it was measured at 100 ± 10 kPa using a paper thickness measuring device MEI-11 manufactured by Citizen Seimitsu.

<Continuous productivity>
Biaxially stretched polypropylene film was started using a biaxially stretched apparatus set to a predetermined thickness, and biaxially stretched polypropylene from the point when the thickness of the obtained biaxially stretched polypropylene film reached the target thickness ± 2%. The time for continuous film formation until the film broke (hereinafter referred to as “continuous film formation time”) was measured. When the thickness reaches the target thickness ± 2%, a sample is cut out from the center in the width direction of the biaxially oriented polypropylene film, and this is measured in accordance with JIS-C2330 using a micrometer (JIS-B7502). The thickness of the sample was measured and confirmed. Based on the obtained continuous film formation time, continuous productivity was evaluated according to the following evaluation criteria.
A: Even if it exceeded 8 hours, the film could be formed without stretching.
B: The film could be formed without stretching and breaking in more than 1 hour and less than 8 hours.
C: The film was stretched and broken within 1 hour, and film formation exceeding 1 hour was impossible.

<Uneven thickness accuracy>
First, a sample is cut out from a biaxially oriented polypropylene film, the thickness of this sample is measured using a micrometer (JIS-B7502) in accordance with JIS-C2330, and the average and standard deviation of 30 points in the width direction are obtained. It was. Next, the coefficient of variation was calculated based on Formula A. Based on the obtained coefficient of variation, the thickness deviation accuracy was evaluated according to the following evaluation criteria.
Coefficient of variation = standard deviation / average × 100 Equation A
(Evaluation standard for uneven thickness accuracy)
A: Less than 0.9% B: 0.9% or more, less than 1.5% C: 1.5% or more

<130 ° C heat shrinkage>
First, in order to measure the heat shrinkage rate in the MD direction, a biaxially stretched polypropylene film was cut into a 20 mm × 130 mm size rectangle, and a 100 mm marked line was attached using a ruler to obtain a sample. In this sample, a side of 130 mm extends in the MD direction. The upper end of this sample was sandwiched between clips, suspended in a dryer, and heat-treated at 130 ° C. for 15 minutes. The sample was taken out from the dryer, the interval between the marked lines was measured with a ruler, and the heat shrinkage rate was calculated using the following formula.
Heat shrinkage rate = (mark interval before heat treatment−mark line interval after heat treatment) / mark line interval before heat treatment × 100
A sample for measuring the thermal contraction rate in the TD direction was also prepared, and the above-described heat treatment was applied to the sample to calculate the thermal contraction rate. This sample is the same as the sample for MD direction measurement except that a side of 130 mm extends in the TD direction.

<140 ° C. heat shrinkage>
The heat shrinkage rate was measured by the same method as that at 130 ° C. except that the heat treatment temperature was changed to 140 ° C. instead of 130 ° C.

<120 ° C. heat shrinkage>
The heat shrinkage rate was measured by the same method as that at 130 ° C. except that the heat treatment temperature was changed to 120 ° C. instead of 130 ° C.

<Margin accuracy>
Unroll the metallized film before slit from the roll of the metallized film before slit, divide the 2.0 mm width insulation margin at the center by the cutting blade, and place the 1.0 mm width insulation margin at the left or right end. And a metallized film having a capacitor element width of 60 mm was wound into a roll. After slitting 3000 m, the insulation margin width was measured, and the deviation width with respect to the 1.0 mm width was determined by difference calculation. Based on this gap width, the margin accuracy was evaluated according to the following evaluation criteria.
(Evaluation criteria for margin accuracy)
A: Deviation width is 0.1 mm or less A: Deviation width exceeds 0.1 mm, 0.2 mm or less B: Deviation width exceeds 0.2 mm, 0.3 mm or less C: Deviation width exceeds 0.3 mm

<Difference between maximum and minimum values of slow axis angle>
The biaxially stretched polypropylene films prepared in Examples and Comparative Examples were equally divided (slit) so as to form a roll having a width of 1200 mm.
Of the plurality of rolls having a width of 1200 mm, the roll at the end in the width direction of the roll before the slit was designated as roll 1.
Further, among the obtained plurality of rolls having a width of 1200 mm, a roll including the central portion (one roll adjacent to the central portion when the central portion overlaps with the slit) was designated as roll 2.
For rolls 1 and 2, the difference between the maximum value and the minimum value of the slow axis angle was determined according to the following <How to determine the difference between the maximum value and the minimum value of the slow axis angle>.
Moreover, the measurement apparatus and measurement conditions are as follows.
<Measurement equipment and measurement conditions>
Measuring device: retardation measuring device RE-100 manufactured by Otsuka Electronics Co., Ltd.
Light source: Laser light emitting diode (LED)
Bandpass filter: 550 nm (measurement wavelength)
Measurement interval: 0.1 sec
Integration count: 10time
Number of measurement points: 15 points
Gain: 10dB
Measurement environment: temperature 23 ° C, humidity 60%
<Determining the difference between the maximum and minimum values of the slow axis angle>
(1) When the total length in the width direction was set to 100%, a measurement sample of 50 mm × 50 mm was cut out centering on a position every 10% from both ends. That is, from one end of the roll, (1200/9) mm, ([1200/9] × 2) mm, ([1200/9] × 3) mm, ([1200/9] × 4) mm, ([1200 / 9] × 5) mm, ([1200/9] × 6) mm, ([1200/9] × 7) mm, ([1200/9] × 8) mm, ([1200/9] × 9) A total of nine measurement samples measuring 50 mm × 50 mm centered on a point of mm were cut out.
(2) Next, the second direction of the measurement sample was set to 0 °, and the acute angle between the second direction of each measurement sample (total nine measurement samples) and the slow axis was measured.
(3) Finally, among the nine measuring samples, the difference between the maximum and minimum angles measured in (2) was determined. The results are shown in Table 5. Table 5 also shows the maximum and minimum values.

In this example, when the biaxially stretched polypropylene film had a width of 1200 mm, the difference between the maximum value and the minimum value of the slow axis angle was less than 6 °. It is clear that the difference becomes smaller as the width (width in the TD direction) becomes narrower. Therefore, in this example, the example is shown only when the biaxially stretched polypropylene film has a width of 1200 mm. However, even if the width is 1200 mm or less (for example, a width of 600 mm), the difference is naturally. Is clearly less than 6 °.

<Measurement of ash content>
About the biaxially stretched polypropylene film of an Example and a comparative example, it measured as follows.
About 200 g of the sample was weighed, transferred to a platinum dish, and incinerated at 800 ° C. for 40 minutes. The ratio (ppm) of ash was measured from the obtained ash residue.
As a result, the ash content of the biaxially stretched polypropylene films of Examples and Comparative Examples was 20 ppm.

[Production of capacitors]
The pre-slit metallized film prepared in the example was slit to a width of 60 mm. Next, the two metallized films were combined. Using the automatic winding machine 3KAW-N2 manufactured by Minato Seisakusho Co., Ltd., the combined metallized film was wound 1137 turns at a winding tension of 250 g, a contact pressure of 880 g, and a winding speed of 4 m / s. . The element wound was heat-treated at 120 ° C. for 15 hours while being pressed at a load of 5.9 kg / cm ² . Thereafter, zinc metal was sprayed onto the element end face. As the spraying conditions, the feed rate was 15 mm / s, the spraying voltage was 22 V, the spraying pressure was 0.3 MPa, and the spraying was performed to a thickness of 0.7 mm. Thus, a flat capacitor was obtained. Lead wires were soldered to the end face of the flat capacitor. Thereafter, the flat capacitor was sealed with an epoxy resin. The epoxy resin was cured by heating at 90 ° C. for 2.5 hours and further heating at 120 ° C. for 2.5 hours. The capacitances of the completed film capacitors were all 75 μF.

DESCRIPTION OF SYMBOLS 5 Metallized film 6 Metallized film before slit 10 Biaxially stretched polypropylene film 21 Insulation margin 30 Metal layer 31 Heavy edge part 32 Active part 51 One edge part in a metallized film 52 The other edge part in a metallized film 300 Metal layer

Claims

The thickness is 1.0 μm to 3.0 μm,
The difference between the heat shrinkage rate of 140 ° C. in the first direction and the heat shrinkage rate of 130 ° C. in the first direction is 0% or more and less than 2.0%,
The difference between the heat shrinkage rate of 140 ° C. in the second direction perpendicular to the first direction and the heat shrinkage rate of 130 ° C. in the second direction is 0% or more and less than 2.3%.
Biaxially stretched polypropylene film.
Wherein the 140 ° C. thermal shrinkage S TD140 in a second direction, wherein the ratio S TD140 / S MD140 between 140 ° C. thermal shrinkage S MD140 in the first direction, claim is 0.200 or more 0.325 or less 2. A biaxially stretched polypropylene film according to 1.
The width in the second direction is 1200 mm or less;
The biaxially stretched polypropylene film according to claim 1 or 2, wherein the difference between the maximum value and the minimum value of the slow axis angle obtained by the following methods (1) to (3) is less than 6 °.
<Determining the difference between the maximum and minimum values of the slow axis angle>
(1) When the total length in the width direction is 100%, a sample for measurement of 50 mm × 50 mm, centered on the position every 10% from both ends, is cut out.
(2) The second direction of the measurement sample is 0 °, and the acute angle between the second direction of each measurement sample and the slow axis is measured,
(3) Among the nine measurement samples, the difference between the maximum and minimum angles measured in (2) is obtained.
The biaxially stretched polypropylene film according to any one of claims 1 to 3, which is used for a capacitor.
Biaxially stretched polypropylene film according to any one of claims 1 to 4,
Having a metal layer laminated on one or both sides of the biaxially oriented polypropylene film,
Metallized film.
A film capacitor having a wound metallized film according to claim 5 or a structure in which a plurality of metallized films according to claim 5 are laminated.
A film roll, wherein the biaxially stretched polypropylene film according to any one of claims 1 to 4 is wound into a roll.