JP2003238034A - Polyester film roll for capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester film roll for a capacitor which solves process problems such as winding displacement, film run-out, and margin accuracy in a capacitor manufacturing process and enables working with high productivity. <P>SOLUTION: In this polyester film roll in which a film with the length of 10000 m or more is wound around a core, a difference R (μm) between a maximum value and a minimum value of a roll diameter in the width direction, the film thickness t1 (μm) and the film length L (m) by gravimetric method satisfy R≤(0.025t1+0.035)×L, a difference H (μm) between the diameter at the left end and the right end of the roll satisfy H≤(0.020t1+0.030)×L, and air content is 5 to 25%. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film roll for a capacitor, and more specifically, when a vapor-deposited capacitor is manufactured by using an extremely thin film, there is a possibility that the film is misaligned during the vapor deposition process. The present invention relates to a polyester film roll for capacitors, which can prevent problems such as vertical wrinkles, film breakage in a slitting process, margin accuracy, and the like, and further has excellent productivity and processability.

[0002]

2. Description of the Related Art Conventionally, capacitors using an organic polymer film as a dielectric have been widely used. As exemplified in Japanese Patent Laid-Open No. 63-194318, a polyester film and a metal foil are alternately wound, or a metal is vapor-deposited on the film to form an electrode, which is wound or laminated to form a capacitor. There is a known technique for obtaining.

With the recent development and miniaturization of electronic devices,
As exemplified in Japanese Patent Publication No. 7-75464, there is an increasing demand for inexpensively obtaining a film capacitor having a large capacity comparable to that of an electrolytic capacitor. Increasing the capacity of film capacitors means thinning and increasing the area of the film that is a dielectric, and it is essential to have technology for manufacturing thinner films with higher productivity and processing capacitors with higher processability than before. It has become to. However, with the thinning and lengthening of the base film, the surface layer winding misalignment at the time of unwinding, the meandering between the rollers on which the running film is arranged, and the breakage of the film, especially during vacuum deposition in the capacitor manufacturing process. It causes various problems such as erosion and significantly impairs the yield of the final product. In particular, during vacuum deposition, winding deviation was a serious problem. this is,
Environment change between raw material roll (base film roll before vapor deposition) manufacturing process and vapor deposition processing process, that is, raw material fabric manufacturing process was manufactured in the presence of 1 atm air, so 1 atm air is produced in the product roll. The phenomenon is considered to be caused by the phenomenon that air is expanded by expanding the layers of the film by exposing the film to a vacuum in the vapor deposition chamber and the balance with the film winding tension becomes unstable. The expansive force of this air corresponds to the pressure difference with the outside, that is, the pressure difference of about 1 atm, and it can be sufficiently suppressed by several tens of sheets when converted into the winding tension of the film, but the outermost layer to be rewound. In the case of several surface layers, this suppression cannot be achieved. For this reason, the balance is lost in the processing apparatus, a mechanical and thermal difference in the width direction occurs in the film, and a phenomenon of winding deviation in which the film shifts in a specific direction occurs. Furthermore, in the vapor-deposited film, vapor deposition lanes that are separated by non-vapor-deposited portions called margins are formed in a number of lines, and in particular, the width of this margin portion (non-vapor-deposited portion) has become narrower in recent years. Has decided the quality level of vapor-deposited products. These margins are formed by partially blocking the vapor deposition with tape or oil, so the finished margin will vary unless the vapor-deposited film and the margin forming material change at the location where evaporated metal adheres to the film. Although it should not be done, in order to form a highly accurate margin as described above, highly accurate delivery is required,
A minute fluctuation of the unwinding film becomes a problem. Achieving this margin accuracy requires that the capacitor has the capacity as designed when the capacitor is manufactured by slitting in the next process and then winding or stacking, and that the normal electrode is formed with the accuracy as designed. It is very important to wind up a reel with a vapor deposition width and a margin width.

[0004]

In the present invention, focusing on the above problems, it is possible to solve process problems such as winding deviation, film breakage, margin accuracy, etc. in the capacitor manufacturing process and process with good productivity. It is intended to provide a polyester film roll for a condenser.

[0005]

The polyester film roll for capacitors of the present invention that achieves the above-mentioned object is
A polyester film roll obtained by winding a film having a length of 10000 m or more around a core, and the difference R (μm) between the maximum value and the minimum value of the roll diameter in the width direction is the film thickness t1 (μm) and the film length measured by the weight method. L (m)
And R ≦ (0.025t1 + 0.035) × L, and the difference between the diameter of the left end and the diameter of the right end of the roll H (μ
m) is a polyester film roll for capacitors which satisfies H ≦ (0.020t1 + 0.030) × L and has an air content of 5 to 25%.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below.

The polyester film roll for capacitors of the present invention is a polyester film roll obtained by winding a film having a length of 10,000 m or more around a core, and the difference R (μm) between the maximum and minimum roll diameters in the width direction.
Satisfies R ≦ (0.025t1 + 0.035) × L for the film thickness t1 (μm) and the film length L (m) by the gravimetric method, and the difference H ( μ
m) is a polyester film roll for capacitors, which satisfies H ≦ (0.020t1 + 0.030) × L and has an air content of 5 to 25%. The polyester film for capacitors of the present invention is
In particular, it is a polyester film roll for capacitors, which has no winding deviation during vapor deposition and has excellent margin precision and vapor deposition processability.

The smaller the difference R between the maximum value and the minimum value of the roll diameter in the width direction, the better the winding appearance of the film roll wound with the film having the vapor deposition film after vacuum vapor deposition. When R> (0.025t1 + 0.035) × L, during vacuum vapor deposition, winding misalignment on the surface layer of the film roll and deterioration of margin accuracy occur, and further, the film with the vapor deposition film after vapor deposition is rolled. When rolled up, the roll is tight and has many wrinkles in the longitudinal direction, so the wrinkles are prone to defects. In addition, film breakage is likely to occur even in the slit process after vapor deposition.

The difference H between the diameter at the left end and the diameter at the right end of the roll
The smaller (μm), the more difficult it is for the film layer on the surface of the film roll to shift in the width direction when the roll is set in a vacuum vapor deposition machine and vacuum exhausted. H> (0.020t1 + 0.
When it is 030) × L, the surface of the film roll is misaligned in the width direction during vacuum evacuation and vapor deposition cannot be performed.

Further, when the diameter distribution in the width direction of the film is continuously drawn as a curve, the maximum value D (μm) of the distance between the straight line connecting both ends of the curve and the curve is the film length L ( With respect to m), D ≦ 0.050 × L is preferable because wrinkles and winding deviation are less likely to occur in the vapor deposition process. Furthermore, in the above D (μm), the maximum value on the convex side (direction in which the roll diameter increases) is D1.
(Μm) and the maximum value on the concave side (direction in which the roll diameter decreases) is D2 (μm), it is preferable that D1> D2 because wrinkles and winding deviation in the vapor deposition step are improved.

From the viewpoints of preventing winding deviation and margin accuracy, the air content is 5 to 25%, preferably 8
~ 20%. If the air content is less than 5%, the hardness of the surface layer of the film roll will be high, and if the film is wound tightly, blocking will occur between the film layers at the time of unwinding, causing breakage of the film. On the other hand, if it exceeds 25%, the amount of air between the film layers becomes large, and winding deviation during vacuum deposition is likely to occur.

The film thickness by the gravimetric method in the present invention is 0.5 to 3.0 from the viewpoint of the element size and the film forming stability.
μm is preferable, and more preferably 0.8 to 3.0 μm.
m, particularly preferably 1.0 to 3.0 μm. If the film thickness exceeds 3.0 μm, the element size becomes large, and if the film thickness is less than 0.5 μm, film forming stability and processability deteriorate, which is not preferable.

The surface roughness SRa (nm) of the film is 1
0 to 100 is preferable, and 15 to 80 is more preferable. If the film surface roughness does not satisfy 10 to 100, the workability may be deteriorated and the withstand voltage may be lowered due to defects such as wrinkles during device processing, which is not preferable.

Further, the surface roughness (maximum height) of the film
SRmax (nm) is preferably 400 to 1800,
It is more preferably 450 to 1400.

The surface roughness SRa (nm) of the film is 1
When the surface roughness (maximum height) SRmax (nm) of the film is 5 to 80 and 450 to 1400, the vapor deposition processability and the withstand voltage are further improved.

In the present invention, the gravimetric thickness t of the film
It is preferable that 1 (μm) and the thickness t2 (μm) by the micrometer method satisfy the following formula 0.1 ≦ t2-t1 ≦ 0.6. By satisfying the above formula,
The amount of air between the film layers is reduced, and the workability is improved. Further, more preferably, 0.1 ≦ t2−t1 ≦ 0.4, and if it is in this range, a smaller capacitor can be obtained.

In the present invention, the film width is preferably 300 mm or more from the viewpoint of the productivity of the capacitor. In addition, in order to improve the efficiency of vapor deposition processing, increase productivity, and reduce costs, the film length is 10,000 m or more,
It is preferably 12000 m or more.

In the present invention, the heat shrinkage rate of the polyester film is from 0.5 to 0.5 in the longitudinal direction from the viewpoint of voltage resistance.
It is preferably 5% and -1.0 to 2.5% in the width direction. The heat shrinkage ratio of the polyester film is more preferably 1.0 to 5.0% in the longitudinal direction and 0 to 2.5 in the width direction.
%. When the heat shrinkage is 1.0 to 5.0% in the longitudinal direction and 0 to 2.5% in the width direction, the winding deviation is prevented during the vacuum deposition process, the margin accuracy is good, and the workability is good.

The cylindrical core of the film roll of the present invention is preferably plastic, fiber-reinforced plastic or metal, which is less likely to be deformed, and more preferably fiber-reinforced plastic from the viewpoint of strength. Examples of the fiber reinforced plastic score include a core obtained by winding carbon fiber or glass fiber into a cylindrical shape, impregnating a thermosetting resin such as an unsaturated polyester resin, and curing the core.

The polyester used in the polyester film for capacitors in the present invention is a polyester containing an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid and a diol as main constituent components. Here, as the aromatic dicarboxylic acid, for example, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,
5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 4,
4'-biphenyl ether dicarboxylic acid, 4,4'-biphenyl sulfone dicarboxylic acid and the like can be used. Among them, preferably terephthalic acid, isophthalic acid,
2,6-naphthalenedicarboxylic acid can be used. As the aliphatic dicarboxylic acid component, for example, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, etc. can be used. These acid components may be used alone or in combination of two or more, and further, an oxy acid such as hydroxybenzoic acid may be partially copolymerized. Further, as the diol component, for example, ethylene glycol,
1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2- Cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2'-bis (4'-β-hydroxyethoxyphenyl) propane, etc. are used. be able to. Among them, ethylene glycol, 1,4-butanediol,
1,6-hexanediol is preferably used. These diol components may be used alone or in combination of two or more.

The polyester used in the polyester film of the present invention is preferably polyethylene terephthalate, a copolymer of ethylene terephthalate and ethylene isophthalate, a copolymer of ethylene terephthalate and ethylene naphthalate, hexamethylene terephthalate and cyclohexane dimethylene. Examples thereof include copolymers with terephthalate, polyethylene terephthalate and polybutylene terephthalate, and blends of polyethylene terephthalate and polyetherimide. From the viewpoint of voltage resistance and stretchability, polyethylene terephthalate or a blend of polyethylene terephthalate and polyetherimide is particularly preferable.

The method for producing the polyester film for capacitors of the present invention will be described below, but the present invention is not limited thereto.

In the present invention, the polyester can be produced by the following method. For example, a method in which an acid component is directly esterified with a diol component and then the product of this reaction is heated under reduced pressure to polycondense while removing the excess diol component, or a dialkyl as the acid component There is a method in which an ester is used, and a transesterification reaction is performed between this and a diol component, and then polycondensation is performed in the same manner as described above. At this time, if necessary, as a reaction catalyst, an alkali metal, an alkaline earth metal,
Manganese, cobalt, zinc, antimony, germanium, and titanium compounds can also be used.

In the polyester of the present invention, if necessary, coloring agents (phosphorus compounds), flame retardants, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, pigments, fatty acid esters, waxes, etc. An organic lubricant or a defoaming agent such as polysiloxane can be blended. Furthermore, in order to impart slipperiness, for example, clay, mica,
It is also possible to mix inorganic particles such as titanium oxide, calcium carbonate, kaolin, talc, wet or dry silica, and organic particles having acrylic acid polymers, polystyrene and the like as constituent components. Also, a method using so-called internal particles, which is formed by deactivating the catalyst or the like added during the polyester polymerization reaction, can be used.

The polyester film is preferably stretched at least uniaxially. More preferably, it is a film stretched in the biaxial direction. The method for biaxially stretching the film may be either a sequential biaxial stretching method or a simultaneous biaxial stretching method. In the case of the sequential biaxial stretching method,
For example, it is general that a thermoplastic resin is extruded onto a cast drum by a T-die extrusion method to form an unstretched film, and then stretched in the machine direction and then in the transverse direction, but it may be stretched in the reverse direction. In the case of the simultaneous biaxial stretching method, any stretching method such as, for example, an inflation simultaneous biaxial stretching method or a stenter simultaneous biaxial stretching method may be adopted, but from the viewpoint of film forming stability and thickness uniformity, the stenter simultaneous biaxial stretching method may be used. Axial stretching is preferred. The stretching temperature is preferably between the glass transition temperature (Tg) of the polyester used for stretching and the temperature rising crystallization temperature (Tcc). The stretching ratio is not particularly limited and may be appropriately determined depending on the type of film polymer used, but is preferably 2 to 8 times in each of the length and width, more preferably 3 to 8 times. Further, after biaxial stretching, it may be re-stretched longitudinally or laterally or longitudinally and laterally.

After that, the biaxially stretched film may be heat-treated. The heat treatment temperature is in the range of 180 ° C. to 240 ° C. in terms of film temperature, and it is preferable to perform the heat treatment for 2 to 30 seconds from the viewpoint of improving the withstand voltage. Following the heat treatment, the relaxation treatment may be performed in the range of 1 to 10%. The film obtained by heat treatment may be once cooled to about room temperature and then aged at a relatively low temperature of 40 to 90 ° C. for about 5 seconds to 1 week. By aging,
The withstand voltage can be further improved. Aging may be performed after metallization.

In the present invention, as a means for forming the surface roughness of the polyester film, for example, a desired surface can be obtained by adding inert particles to the polyester film. To further exemplify, as the inert particles to be added, silica, calcium carbonate, titanium oxide,
Kaolin, talc, alumina and the like can be used. Further, crosslinked polymer particles and the like can also be used.
When these particles are added at the polymerization stage, if the dispersion is not good, coarse projections on the film surface may be caused, which may adversely affect the insulation resistance and the withstand voltage. Dispersing with a jet agitator or media dispersion is effective for obtaining the surface of the present invention. When a primer layer is provided on the film, particles can be added to the primer layer to form the desired surface.

In the width direction of the polyester film roll wound on a cylindrical core, the difference R (μm) between the maximum and minimum roll diameters, the difference H (μm) between the left end diameter and the right end diameter of the roll, and In order to satisfy the specified range of the distance D (μm) between the diameter distribution curve and the straight line connecting both ends of the curve, it is necessary to adjust the thickness unevenness with a die for casting the melt-extruded polymer into a sheet on a cooling drum. Refinement,
The feedback method for adjusting the thickness unevenness with the spinneret and the conditions for winding on a roll are extremely important.

The difference R between the maximum value and the minimum value of the roll diameter in the width direction of the film roll wound on the cylindrical core.
(Μm) is R ≦ L with respect to the film length L (m).
Satisfying (0.025t1 + 0.035) × L, the difference between the diameter of the left end and the diameter of the right end of the roll H ≦ (0.020t1 +
To satisfy 0.030) × L, the following method is extremely effective.

That is, when the melted polyester is extruded from a die and cast into a sheet shape, the thickness unevenness is adjusted by one of a pair of lips forming a slit gap of the die and arranged along the slit extending direction. There is a method for controlling the thickness to a desired value by providing a slit gap adjusting bolt and rotating the adjusting bolt forward or backward. Incidentally, such a control method is disclosed in, for example, Japanese Patent Laid-Open No.
This is a well-known control method as proposed in Japanese Patent Laid-Open No. 108586. The method of controlling the profile of the film thickness by this control means, after biaxially stretching a wide polymer discharged from the die to a biaxially stretched film,
The thickness of the biaxially stretched film is measured and controlled to bring it closer to the target thickness profile. When the thickness control range (upper and lower limit values) set in advance as a target is deviated, the film thickness is controlled by the control method described above. In order to obtain R and H in the range of the present invention, this thickness control range (dead zone value) is usually ± 0.05 μ
m is more preferable, and it is more preferably ± 0.01 μm, and if it is ± 0.0 μm, the thickness in the film width direction becomes more uniform, and the thickness unevenness in the film width direction is 35 with respect to the average thickness of the film. % Or less, preferably 25% or less.

In the film of the present invention, after biaxial stretching and heat treatment, the film thickness is measured in-line and the measurement result is fed back to the cap bolt, but the optical interference type is used as the thickness meter. preferable. Further, while making the film thickness unevenness in the width direction uniform, 10
After the film wound up to 000 m or more is cut into a predetermined width and length, it is wound up on a cylindrical core and the film roll is stored for about 4 to 12 hours in an environment of a temperature of 10 to 35 ° C. After letting air out, the diameter of the film roll is measured in the width direction, the width direction is plotted on the graph in the X axis and the diameter is plotted in the Y axis, and the information of R and H read from the plotted curve is indicated by the spinneret. The difference R (μm) between the maximum value and the minimum value of the roll diameter in the width direction is changed to the film length L (m) by feeding back to the thickness unevenness adjustment and rotating the specified position of the thickness adjusting bolt forward or backward. On the other hand, R ≦ (0.025t1 + 0.03
5) x L and the difference H (μm) between the diameter of the left end and the diameter of the right end of the roll is H ≦ (0.020t1 + 0.030)
The relationship of xL can be satisfied.

In order to satisfy the relation of D ≦ 0.050 × L of the present invention, the slit condition of the film is important in addition to the above-mentioned control of the film thickness unevenness, and the air content rate in the film roll is 5 to 5. It is preferably set to 25%.

The roll slit conditions for obtaining the polyester film for capacitors of the present invention are as follows: the tension at the time of unwinding and winding is 0.5 to 8.0 kg / m, and the surface pressure at the time of winding is 5 to 60 kg.
It is preferable that the kg / m and the slit speed are 140 to 280 m / min.

The polyester film roll of the present invention comprises:
In the capacitor manufacturing process, excellent results can be obtained during vapor deposition and slitting.

[Characteristic Measuring Method] (1) The difference between the maximum value and the minimum value in the width direction of the roll R (μm) and the difference between the diameter of the left end of the roll and the diameter of the right end H (μm) Dimensional accuracy of the film roll outer circumference is 100
Measure with a tape measure of μm, and determine the diameter from the outer circumference.
From the point 2 mm inward from the end of the roll, the width was measured every 5 mm over the entire width. The width direction was plotted on the X axis and the diameter was plotted on the Y axis. From the plotted curve, the difference between the maximum value and the minimum value of the diameter was R (μm ), The difference in diameter between the ends of the film roll is H (μ
m).

The both ends of the plotted linear distribution curve are connected by straight lines, and the distance between the straight line and the farthest point on the distribution curve is D (μm). The distance between the straight line and the distribution curve is defined as D1 (μm) on the convex side and D2 (μm) on the concave side.

(2) Air content (%) The outer peripheral length of the wound film roll is measured with a dimensional accuracy of 100.
Measure with a tape measure of μm, and determine the roll diameter from the outer circumference. The roll diameter is measured every 50 mm from the point 2 mm inside from the end of the roll over the entire width, and the average value is used. The air content rate is α = {100π (d1 ² −d2 ² ) / 4t1L} −10 by the following formula.
0 α: air content (%) t1: gravimetric film thickness (μm) L: roll length (m) d1: roll diameter (mm) d2: core diameter (mm)

(3) Surface roughness of film (center surface average roughness SRa, maximum height SRmax) Using a three-dimensional surface roughness meter ETB-30HK manufactured by Kosaka Laboratory, a stylus type was used under the following conditions. Needle tip diameter: 2 μm Stylus load: 10 mg Measurement length: 1 mm Feed pitch: 50 μm Number of measurements: 40 Cutoff value: 0.25 mm Measured.

When the roughness curved surface f (x, y) is obtained under the above conditions, SRa is expressed by the following equation.

[0040]

[Formula 1] (However, lx; measurement length = 1 mm, ly = (feed pitch) ×
(Number of measurement lines) = 2 mm, S = 1x × ly)

The maximum peak and the deepest valley in the above measurement range are sandwiched by two surfaces parallel to the average surface, and the distance therebetween is defined as the maximum height SRmax.

(4) Film thickness measurement (4.1) Weight method Thickness measurement The weight of the sample was measured, and the density of polyethylene terephthalate was 1.40, and the following formula t2 (μm) = film weight (g) / ( The film width (m) x film length (m) x density is calculated.

(4.2) Micrometer Method A thickness measurement sample is measured with a micrometer at 10 points in each of the width and length directions of the film, and the average value is used.

(5) Evaluation of margin accuracy at the time of vacuum deposition, element winding at the time of manufacturing a capacitor Using a resistance heating type metal deposition apparatus, the pressure in the vacuum chamber was set to 10 ^-4.
Aluminum was vacuum-deposited and wound so that the surface resistance was 2 Ω / □ on one surface of the polyester film under Torr. At that time, vapor deposition was performed in a stripe shape having a margin portion running in the longitudinal direction (a vapor deposition portion width of 8.0 mm and a margin portion width of 1.0 mm repeated).

It should be noted that, after the roll-shaped film before being vapor-deposited and before the roll-shaped film is subjected to the vapor deposition step, the roll-shaped film is moisture-proof packaged so that moisture from the outside does not enter. The vapor-deposited film obtained as described above was slit to the left or right in the shape of a tape having a width of 4.5 mm having a margin portion having a width of 0.5 mm. At this time, the margin width, which is a portion not vapor-deposited, is measured every 20 cm in the longitudinal direction for 5 m, and the margin width range margin accuracy is 0.5 ± 0.15 based on the following maximum and minimum margin width values. Ultra high accuracy ◎ 0.5 ± 0.25 High accuracy ○ 0.5 ± 0.50 Poor accuracy × Margin accuracy was evaluated.

Each of the obtained left margin and right margin vapor-deposited polyester films was wound together to obtain a wound body. At this time, the vapor deposition portion is 0.5 mm in the width direction.
The two films were wound while being shifted so that each film protrudes. KAW-4NHB manufactured by Minato Manufacturing Co., Ltd. was used for winding the element. Remove the core material from this roll and leave it at 150 ° C.
It was pressed at a temperature of 10 kg / cm ² and a pressure for 5 minutes. Metallicons were sprayed on the both end faces to form external electrodes, and lead wires were welded to the metallicons to obtain a wound-type capacitor element.

When manufacturing the above-mentioned capacitor, visually observing from the beginning to the end of winding, those with wrinkles and deviations are regarded as rejected, and the ratio of the number of rejected parts to the total number of manufactured parts is a percentage. Was used as an index of workability (hereinafter referred to as device winding yield). The higher the device winding yield, the more preferable. 95% or more was rated as good, 85% or more and less than 95% was rated as good, and less than 85% was rated as bad.

[0048]

EXAMPLES The present invention will be described below based on examples.

Example 1 Polyethylene terephthalate was used as the polyester resin. At the polymerization stage, 1.0% by weight of aggregated silica particles having an average particle size of 1.5 μm was added by a known method to produce chips.

The chips were vacuum dried at 180 ° C., fed to an extruder and melted at 285 ° C., and then a pair of lips forming a slit gap were provided and one of the lips was arranged along the slit extending direction. A plurality of slit gap adjusting bolts were also discharged through a die to form a sheet, and the sheet was cast on a cooling drum. This film was heated to 105 ° C. and stretched 3.5 times in the longitudinal direction, then stretched 3.8 times in the width direction at 105 ° C., subsequently subjected to 1% relaxation treatment at 215 ° C. A biaxially stretched film having a thickness of 86 μm and a micro-method thickness of 0.98 μm was obtained.

Using a slitter, this film was slit at a speed of 150 m / min and an oscillation speed of 125 mm / mi.
n, oscillation width 80 mm, unwinding tension 2.0 kg / m, initial winding tension 1.7 kg / m, base surface pressure 10 as winding conditions
kg / m, initial surface pressure 10 kg / m, width 315 mm, length 1200
After slitting to 0 m and storing the slit polyester film roll at 20 to 25 ° C. for 8 hours, R and H were measured. The above-mentioned feedback method (dead zone value ± 0.0 μm) is repeated along with the film roll of 12000 m by rotating the bolt at a specific position of the slit gap adjusting bolt forward and backward so that R and H are within the specified range. , R and H were obtained in a predetermined range to obtain a polyethylene terephthalate film roll. R of the obtained film roll =
220 μm, H = 100 μm, D = 150, film surface roughness SRa = 51.0 nm, SRmax =
It was 1139 nm. The air content was 16%.

Aluminum was vacuum-deposited on one surface of the obtained biaxially stretched film so that the surface resistance was 2 Ω / □, and the vapor-deposited film was left or right with a width of 4.5 mm having a margin of 0.5 mm. The tape was slit into 70 tape-shaped slits (hereinafter,
Referred to as reel sample). Then, it wound and the capacitor was obtained. The maximum value of the margin width of one reel sample was 0.66 mm, the minimum value was 0.34 mm, and the element winding yield was 95%.

(Example 2) A film was produced in the same manner as in Example 1 except that the winding conditions in the slitting step were an oscillation width of 150 mm and an initial surface pressure of 5 kg / m to obtain a capacitor. R = 280μ of the obtained film roll
m, H = 50 μm, D = 300 μm, the film surface roughness is SRa = 52.0 nm, SRmax = 145.
It was 0 nm. The air content was 18%.

The maximum value of the margin width of the reel sample is
It was 0.58 mm, the minimum value was 0.40 mm, and the element winding yield was 98%.

(Embodiment 3) Dead band value ± 0.01 μm, winding condition in slit process is oscillation speed 100 mm
/ min, width 40 mm, initial tension 1.2 kg / m, initial surface pressure 5 kg / m
A film was produced in the same manner as in Example 1 except that the above was used to obtain a capacitor. R of the obtained film roll =
670 μm, H = 520 μm, D = 240 μm,
The film surface roughness is SRa = 56.0 nm, SRma
x = 1500 nm. The air content was 23%.

The maximum value of the margin width of the reel sample is
The value was 0.70 mm, the minimum value was 0.34 mm, and the device winding yield was 95%.

(Example 4) A film was produced in the same manner as in Example 1 except that the winding condition in the slitting step was an initial tension of 2.3 kg / m to obtain a capacitor. R = 380 μm, H = 80 μm, D = 4 of the obtained film roll
The film surface roughness is SRa = 49.
It was 0 nm and SRmax = 1050 nm. The air content was 10%.

The maximum value of the margin width of the reel sample is
The value was 0.60 mm, the minimum value was 0.39 mm, and the device winding yield was 88%.

(Comparative Example 1) Dead band value ± 0.05 μm, winding condition in slit process was set to oscillation speed 75 mm / m.
A film was produced in the same manner as in Example 1 except that in was used to obtain a capacitor. R of the obtained film roll
= 780 μm, H = 400 μm, D = 330 μm, film surface roughness SRa = 53.0 nm, SR
max = 1120 nm. Air content is 15%
Met.

The maximum value of the margin width of the reel sample is
The value was 0.76 mm, the minimum value was 0.24 mm, and the device winding yield was 95%.

(Comparative Example 2) Dead band value ± 0.05 μm, winding conditions in the slitting process were set at an oscillation speed of 75 mm / m.
A film was produced in the same manner as in Example 1 except that the in was 40 mm, the initial tension was 1.2 kg / m, and the capacitor was obtained. R = 740 μm, H = 7 of the obtained film roll
40 μm, D = 680 μm, film surface roughness SRa = 52.0 nm, SRmax = 1450 nm
Met. The air content was 19%.

The maximum value of the margin width of the reel sample is
0.79 mm, the minimum value was 0.26 mm, and the element winding yield was 82%.

(Comparative Example 3) Dead band value ± 0.05 μm, winding conditions in the slitting process were set at an oscillation speed of 75 mm / m.
A film was produced in the same manner as in Example 1 except that the in was 40 mm, the initial tension was 1.2 kg / m, and the capacitor was obtained. R = 900 μm, H = 8 of the obtained film roll
50 μm, D = 310, and the film surface roughness is S
Ra = 52.0 nm and SRmax = 1250 nm. The air content was 20%.

The maximum value of the margin width of the reel sample is
The value was 0.85 mm, the minimum value was 0.17 mm, and the device winding yield was 85%.

(Comparative Example 4) Dead band value ± 0.05 μm, winding conditions in the slitting process were set at an oscillation speed of 75 mm / m.
A film was produced in the same manner as in Example 1 except that in, width was 40 mm, and initial tension was 3.0 kg / m to obtain a capacitor. The obtained film roll has R = 1100 μm and H =
830 μm, D = 420 μm, film surface roughness SRa = 48.0 nm, SRmax = 1000 nm
Met. The air content was 6%.

The maximum value of the margin width of the reel sample is
The value was 0.90 mm, the minimum value was 0.15 mm, and the device winding yield was 75%.

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[Table 1]

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According to the present invention, it is possible to provide a polyester film roll for a capacitor, which can solve process problems such as winding deviation, film breakage and margin accuracy in the capacitor manufacturing process and can be processed with high productivity. You can The polyester film roll of the present invention is particularly excellent in productivity and processability.

Claims (8)

[Claims] 1. A polyester film roll obtained by winding a film having a length of 10,000 m or more around a core, wherein a difference R (μ) between the maximum value and the minimum value of the roll diameter in the width direction.
m) satisfies R ≦ (0.025t1 + 0.035) × L for the film thickness t1 (μm) and the film length L (m) by the gravimetric method, and the difference between the diameter of the left end and the diameter of the right end of the roll. H (μ
m) satisfies H ≦ (0.020t1 + 0.030) × L, and has an air content of 5 to 25%. A polyester film roll for capacitors. 2. The maximum value D (μm) of the distance between the diameter distribution curve in the width direction and the straight line connecting both ends of the curve is D ≦ 0.050 × L with respect to the film length L (m). The polyester film roll for capacitors according to claim 1. 3. The maximum value on the convex side and the maximum value on the concave side of the distance D (μm) between the diameter distribution curve in the width direction and the straight line connecting both ends of the curve are D1 (μm) and D2 (μm), respectively.
The polyester film roll for capacitors according to claim 1 or 2, wherein D1> D2. 4. Film thickness t1 (μm) by gravimetric method
Is 0.5 to 3.0, The polyester film roll for capacitors according to any one of claims 1 to 3. 5. Surface roughness of film (center surface average roughness)
SRa (nm) is 10-100, The polyester film roll for capacitors in any one of Claims 1-4. 6. The polyester film roll for capacitors according to claim 1, wherein the polyester is polyethylene terephthalate or a blend of polyethylene terephthalate and polyetherimide. 7. Surface roughness (maximum height) SRm of the film
ax (nm) is 400 to 1800.
The polyester film roll according to any one of 1. 8. The gravimetric thickness t1 (μm) and the micrometric thickness t2 (μm) of the film satisfy 0.1 ≦ t2-t1 ≦ 0.6. Polyester film roll for capacitors.