JP2008138103A - Biaxially oriented polyester film roll - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester film roll which, when used in a capacitor production process, can be processed with good productivity solving process troubles such as thermal deterioration and poor margin precision. <P>SOLUTION: The biaxially oriented polyester film roll is a polyester film roll produced by winding a film around a core, wherein the inner layer hardness h1 is 90 or higher along the length of 5-25% of the entire length from the core for the original film, the inner layer hardness h2 is 95 or smaller along the length of 30-80% of the entire length, and the inner layer hardness h3 satisfies the expression (1): 0≤(h1-h3)≤5 along the length of 85-95% of the entire length, and the air content is 5-25%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polyester film roll, and more specifically, when an extremely thin film is used, particularly when a vapor deposition capacitor is produced, film winding deviation or heat loss in a vapor deposition process, and film breakage in a slit process. Further, the present invention relates to a polyester film roll that can prevent troubles such as margin accuracy and has excellent productivity and workability.

  Conventionally, capacitors using an organic polymer film as a dielectric have been widely used. As exemplified in Patent Document 1 and the like, in particular, a technology for obtaining a capacitor by winding a polyester film and a metal foil alternately, or by vapor-depositing a metal on a film to form an electrode, and winding or laminating the electrode. It has been known.

In recent years, with the development and miniaturization of electronic devices and the like, as exemplified in Patent Document 2, there is an increasing demand for obtaining a film capacitor having a large capacity comparable to an electrolytic capacitor at low cost. Increasing the capacity of film capacitors, that is, reducing the film thickness and area of dielectric films, has traditionally been a technology for manufacturing thinner films with higher productivity and processing capacitors with higher workability. Has become essential. However, with the thinning and lengthening of the base film, especially during vacuum deposition in the capacitor manufacturing process, the surface layer winding deviation at the time of unwinding, meandering between the rollers on which the traveling film is arranged, or heat loss Various problems such as film breakage are caused, and the yield of the final product is significantly hindered. Vapor deposition films are formed with a number of vapor deposition lanes that are separated by non-deposited portions called margins (non-deposited portions), and in recent years the width of these margin portions has become narrower, and the accuracy of this portion has been reduced. The quality level of the deposited product has been determined. Major problems in processing include heat loss and margin (non-deposition portion) runout. This is thought to be due to the fact that the heat loss occurs when the traveling film floats from the cooling can and receives excessive heat, and the margin fluctuation causes the running of the original fabric to become unstable during unwinding. In both cases, it is considered that the balance of tension is lost in the processing apparatus when unwinding the raw material. These margins are formed by partially blocking vapor deposition with tape or oil. Especially when depositing on both sides of the film, the margin accuracy (dimensions on the front and back of the film) should not fluctuate if the deposited film and the margin forming material do not fluctuate where the evaporated metal adheres to the film. In order to form a high-precision margin as described above, high-precision feeding is required, and minute fluctuations in the unwinding film become a problem. Achieving this margin accuracy means that the capacitor is manufactured by slitting and then winding or stacking in the next process so that it has the designed capacity and forms a normal electrode. It is very important for winding a reel having a deposition width and a margin width. In order to solve these problems, Patent Documents 3, 4, and 5 disclose that the winding hardness when winding a film is specified. However, even these methods have not yet sufficiently solved process problems such as film breakage due to heat loss and margin accuracy in a capacitor manufacturing process that requires high-precision feeding in recent years.
JP 63-194318 A Japanese Patent Laid-Open No. 02-88972 JP 11-59986 A Japanese Patent Laid-Open No. 02-88972 JP-A 61-136746

  This invention pays attention to the above problems, and solves process problems such as film breakage due to heat loss and margin accuracy in the capacitor manufacturing process, and provides a polyester film roll that can be processed with high productivity. Objective.

  An object of the present invention described above is a polyester film roll obtained by winding a film around a core, and an inner layer hardness h1 between 5% and 25% of the total length from the raw fabric core is 90 or more and 30% to 80%. The inner layer hardness h2 between% length is 95 or less, the inner layer hardness h3 from 85% to 95% length satisfies the following formula (1), and the air content is 5% or more and 25% or less. This can be achieved by an axially stretched polyester film roll.

    0 ≦ (h1-h3) ≦ 5 (1)

  According to the present invention, it is possible to provide a polyester film roll that can solve process problems such as film breakage due to heat loss and margin accuracy in a capacitor manufacturing process and can be processed with high productivity.

  The present invention is a polyester film roll formed by winding a film around a core, and the inner layer hardness h1 between 5% and 25% is 90 or more and between 30% and 80% of the total length from the raw roll core. A biaxially stretched polyester film having an inner layer hardness h2 of 95 or less, an inner layer hardness h3 of 85% to 95% length satisfying the following formula (1), and an air content of 5% to 25%: It is a roll.

0 ≦ (h1-h3) ≦ 5 (1)
It is preferable that h1, h2, and h1-h3 are within the above ranges because both the heat loss state during vapor deposition and the margin state during slit processing are favorable. If h1 is less than 90, h2 is greater than 95, or the relationship between h1 and h3 is out of the formula (1), the tension balance between unwinding and winding is lost, the transport of the running film becomes unstable, heat is lost, This is not preferable because it tends to be a defect of margin fluctuation, and the film is likely to be cut in the slit process after vapor deposition. In particular, if the range of the formula (1) is deviated, it is not preferable because it is difficult to perform a vapor deposition process over the entire surface of the raw fabric to the entire length of the core.
Preferably, h1 is 92-100, h2 is 80-94, and the value of (h1-h3) is 0-3.

  Further, from the viewpoint of winding deviation prevention and margin accuracy, the air content is 5% or more and 25% or less, and preferably 8% or more and 20% or less. When the air content is less than 5%, the surface hardness of the film roll becomes high, and it is not preferable because the film roll is hard and blocking occurs between the film layers at the time of unwinding. On the other hand, if it exceeds 25%, the amount of air between the film layers increases, unwinding / conveying becomes unstable, heat is lost, and margin fluctuation tends to occur, which is not preferable.

  In the polyester film roll of the present invention, the difference R (μm) between the maximum value and the minimum value of the roll diameter in the width direction is expressed by the formula (for the film thickness t1 (μm) and the film length L (m) by the gravimetric method. It is preferable to satisfy 2).

R ≦ (0.0025 × t1 + 0.0035) × L (2)
The smaller the difference R between the maximum value and the minimum value of the roll diameter in the width direction, the better the roll appearance of the film roll wound up with the film with the deposited film after vacuum deposition. When R> (0.0025 × t1 + 0.0035) × L, during vacuum deposition, winding deviation on the surface layer of the film roll and deterioration of margin accuracy occur, and a film with a deposited film after deposition is rolled. When rolled up into a shape, a large number of wrinkles in the longitudinal direction are included in the roll, which is not preferable because the wrinkled portion tends to be a defect. Further, it is not preferable because the film breakage is likely to occur in the slit process after vapor deposition.
Further, it is preferable that the difference H (μm) in the diameters at both ends of the roll satisfies the formula (3) with respect to the thickness t1 (μm) and the film length L (m).

H ≦ (0.0020 × t1 + 0.0030) × L (3)
The smaller the difference H (μm) in the diameters at both ends of the roll, the more preferable it is because the film layer on the surface of the film roll is less likely to shift in the width direction when the roll is set in a vacuum vapor deposition machine and evacuated. When H> (0.0020 × t1 + 0.0030) × L, the film roll surface tends to be misaligned in the width direction when evacuated, which is not preferable.

  The film thickness t1 by the weight method in the present invention is preferably 0.5 to 3.0 μm, more preferably 0.8 to 3.0 μm, and particularly preferably 1.0 from the viewpoint of element size and film formation stability. ˜3.0 μm. When the film thickness exceeds 3.0 μm, the element size increases. When the film thickness is less than 0.5 μm, the film forming stability and workability deteriorate, which is not preferable.

  10-100 are preferable and, as for surface roughness SRa (nm) of a film, More preferably, it is 15-50. When the film surface roughness Sra (nm) does not satisfy 10 to 100, the withstand voltage may be lowered due to defects such as deterioration of workability and wrinkles during device processing, which is not preferable.

  Furthermore, the surface roughness (maximum height) SRmax (nm) of the film is preferably from 400 to 1800, and more preferably from 800 to 1400 because the vapor deposition processability and the voltage resistance are further improved.

  In the present invention, it is preferable that the film thickness t1 (μm) by the weight method and the film thickness t2 (μm) by the micrometer method satisfy the following formula (4).

0.1 ≦ (t2−t1) ≦ 0.6 (4)
Satisfying the above formula (4) is preferable because the amount of air between the film layers is reduced and the processability is improved. More preferably, the following formula (5) is satisfied, and it is preferable that this range is obtained because a smaller capacitor can be obtained.

0.1 ≦ (t2−t1) ≦ 0.4 (5)
In the present invention, from the viewpoint of capacitor productivity, the film width is preferably from 200 mm to 1500 mm, and more preferably from 300 mm to 1000 mm, from the viewpoint of practicality, although it depends on the equipment specifications of the processing step.

  Moreover, in order to improve the efficiency of vapor deposition processing, increase productivity, and reduce cost, the film length is preferably 10,000 m to 40000 m, more preferably 12000 m to 40000 m. On the other hand, if the film length exceeds 40,000 m, continuous winding becomes difficult, which is not practical.

  As the material of the winding core when the polyester film of the present invention is wound into a roll shape, fiber reinforced plastic, iron or the like can be used. However, when fiber reinforced plastic is used, the raw material generated due to tightening over time. This is preferable in that the change in shape and the generation of wrinkles can be reduced.

  Further, the deflection when the winding core is rotated is preferably 0.20 mm or less, and more preferably 0.15 mm or less. The cylindricity of the winding core is also preferably 0.20 mm or less, and more preferably 0.15 mm or less. If the range where the runout and cylindricity are not satisfied is satisfied, wrinkles are likely to occur when the film is wound, which is not preferable.

  The axial bending strength of the winding core is preferably 180 MPa or more, and more preferably 200 MPa or more. If a winding core less than this range is used, the winding core may be deformed by the tension and contact pressure applied when the film is wound. Moreover, it is preferable that the axial direction elasticity modulus of a core material is 9.8 GPa, More preferably, it is 13.7 GPa or more. If a core that is less than this range is used, the winding core may be deformed as in the previous period, which is not preferable. A method for setting the strength of the winding core in such a range is not particularly limited. For example, it is effective to appropriately adjust the amount of the glass fiber system in the fiber reinforced plastic base material, and the thickness of the base material is adjusted. The desired strength can also be obtained by adjusting.

  Further, the surface roughness Ra of the winding core is preferably 0.5 μm or less, more preferably 0.3 μm or less. If a winding core made of a material less than this range is used, the irregularities on the core surface are transferred to the film surface, and the effects of the present invention are not fully exhibited, which is not preferable. A method for setting the surface roughness of the winding core in such a range is not particularly limited. For example, a desired surface roughness can be obtained by providing a resin layer on the surface of the winding core and grinding the surface with high accuracy.

  The surface hardness of the winding core is preferably 65 ° or more, and preferably 80 ° or more. When a winding core that is less than this range is used, the surface of the winding core may be deformed by the tension and contact pressure applied during film winding, and the surface properties and the original fabric shape of the film may be deteriorated. A method for adjusting the surface hardness of the winding core to such a range is not particularly limited, but for example, a hard resin such as an epoxy resin is used for the core surface, and the thickness can be adjusted appropriately.

  Furthermore, the diameter of the winding core is preferably 50 to 500 mm, more preferably 100 to 350 mm, and particularly preferably 150 to 250 mm.

  The polyester used for the polyester film in the present invention is a polyester mainly composed of aromatic dicarboxylic acid or aliphatic dicarboxylic acid and diol. Here, as the aromatic dicarboxylic acid, for example, terephthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid and the like can be used. Of these, terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferably used. These acid components may be used alone or in combination of two or more thereof, and further may be partially copolymerized with oxyacids such as hydroxybenzoic acid. Further, as the diol component, for example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, diethylene glycol and the like can be used. Of these, ethylene glycol, 1,4-butanediol, and 1,6-hexanediol are preferably used. These diol components may be used alone or in combination of two or more.

  The polyester used for the polyester film in the present invention is preferably polyethylene terephthalate or polyethylene naphthalate from the viewpoint of voltage resistance and stretchability.

  Although the manufacturing method of the polyester film of this invention is demonstrated below, this invention is not limited to this.

  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 perform polycondensation while removing excess diol component, or a dialkyl as an acid component There is a method in which an ester is used for ester exchange reaction between this and a diol component, followed by polycondensation in the same manner as described above. At this time, an alkali metal, alkaline earth metal, manganese, cobalt, zinc, antimony, germanium, or titanium compound can also be used as a reaction catalyst as necessary.

  In the polyester in the present invention, if necessary, an organic lubricant such as an anti-coloring agent (phosphorus compound), a flame retardant, a heat stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, a pigment, a fatty acid ester, a wax, Alternatively, an antifoaming agent such as polysiloxane can be blended.

  The polyester film is a biaxially stretched film, and 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 the thermoplastic resin is extruded on a cast drum by a T-die extrusion method to form an unstretched film, and then stretched in the order of the machine direction and the transverse direction. You may extend | stretch in order of a horizontal direction and a vertical direction. In the case of the simultaneous biaxial stretching method, for example, any of the stretching methods such as inflation simultaneous biaxial stretching method and stenter simultaneous biaxial stretching method may be adopted, but from the viewpoint of film formation stability and thickness uniformity, An axial stretching method is preferred. The stretching temperature is preferably between the glass transition temperature (Tg) and the temperature-rising crystallization temperature (Tcc) of the polyester used for stretching. The draw ratio is not particularly limited, and is appropriately determined depending on the type of film polymer used. Preferably, the length and width are 2 to 8 times, more preferably 3 to 8 times. Further, after biaxial stretching, it may be re-stretched vertically or horizontally, or vertically and horizontally.

  Further thereafter, the film after biaxial stretching may be heat-treated. The heat treatment temperature is preferably in the range of 180 ° C. to 240 ° C. for 2 to 30 seconds from the viewpoint of improving the withstand voltage. Subsequent to the heat treatment, the relaxation treatment may be performed within a range of 1 to 10%. After the film obtained by the heat treatment is once cooled to about room temperature, it can be further aged at a relatively low temperature of 40 to 90 ° C. for 5 seconds to 1 week. By performing aging, the withstand voltage can be further improved. Aging may be performed after metal deposition.

  Furthermore, as a means for forming the surface roughness of the polyester film in order to impart slipperiness, for example, inorganic particles such as clay, mica, titanium oxide, calcium carbonate, kaolin, talc, wet or dry silica, acrylic It is also possible to blend organic particles containing acid-based polymers, silicone, cross-linked polystyrene, and the like as constituent components. Further, a method using so-called internal particles formed by deactivating a catalyst or the like added during the polyester polymerization reaction can also be used.

  When these particles are added in 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 voltage resistance. For example, after making these inert particles into an ethylene glycol slurry, it is effective to carry out dispersion with a jet agitator or media dispersion, remove coarse particles by filtration, and then add to the polymerization reaction process.

  Moreover, when providing a primer layer on a film, particle | grains can also be added to a primer layer and the target surface can also be formed.

  In the polyester film roll wound up on the cylindrical core, the inner layer hardness h1 between 5% and 25% length is 90 or more and the inner layer hardness h2 between 30% and 80% length is 95 or less with respect to the total length from the raw roll core. Furthermore, in order for the difference between h1 and the inner layer hardness h3 of 85% to 95% length to satisfy 0 ≦ (h1−h3) ≦ 5, the slit condition at the time of winding on the roll is extremely important. The following method is extremely effective.

  As roll slit conditions for obtaining the polyester film of the present invention, the tension at the time of winding of less than 30% of the entire length from the core is 0.5 kg / m to 8.0 kg / m, and further, at the time of winding The surface pressure is set to 5 kg / m to 60 kg / m, and the tension and the surface pressure at the time of winding are linearly increased from a time point of 30% or more from the original roll core to the entire length, and finally 10 to 100%. It is preferable to raise in the range.

  Here, the surface pressure is a pressure applied to the film surface during winding, and the surface pressure can be adjusted via a contact roll during winding.

  The inner layer hardness h1 between 5% and 25% length is 90 or more and the inner layer hardness h2 between 30% and 80% length is 95 or less with respect to the total length from the raw roll core, and further, h1 and 85% to 95 The method of obtaining a polyester film roll in which the difference in% inner layer hardness h3 satisfies 0 ≦ (h1−h3) ≦ 5 is not limited to this method, but the tension during winding from the core to the surface layer By controlling the surface pressure, the difference between h1 and h3 is reduced, the conveyance of the unwinding film is stabilized from beginning to end, heat is lost, and margin accuracy is improved.

  The slit speed is preferably in the range of 140 m / min to 280 m / min, and the air content in the film roll is preferably 5% to 25%.

  The difference R (μm) between the maximum and minimum roll diameters of the present invention and the difference H (μm) between the left end diameter and the right end diameter of the roll satisfy the specified ranges (the following formulas (2) and (3)). In order to achieve this, it is extremely important to increase the fineness of the thickness unevenness adjustment in the die that casts the melt-extruded polymer into a sheet into a cooling drum, the feedback method for adjusting the thickness unevenness in the die, and the conditions for winding the roll.

R ≦ (0.0025 × t1 + 0.0035) × L (2)
H ≦ (0.0020 × t1 + 0.0030) × L (3)
That is, the difference R (μm) between the maximum value and the minimum value of the roll diameter in the width direction of the film roll wound up on the cylindrical winding core is R ≦ (0.0025 ×) with respect to the film length L (m). In order to satisfy t1 + 0.0035) × L and satisfy the difference H ≦ (0.0020 × t1 + 0.0030) × L between the diameters of both ends of the roll, the following method is effective.

  For adjusting the thickness unevenness when extruding the molten polyester from the die and casting it into a sheet, for adjusting the slit gaps arranged along the lateral direction of the slit on one of the pair of lips forming the slit gap of the die A desired thickness can be controlled by providing a bolt and rotating the adjusting bolt forward or backward. Such a control method is a known control method as proposed in, for example, Japanese Patent Laid-Open No. 7-108586. The method of controlling the film thickness profile by this control means is to biaxially stretch a wide polymer discharged from the die to obtain a biaxially stretched film, and then measure the thickness of the biaxially stretched film. It can be controlled to be close to the target thickness profile. When the thickness management range (upper and lower limit values) set in advance as a target is deviated, the film thickness is controlled by the aforementioned control method. In order to obtain R and H within the scope of the present invention (that is, to satisfy (2) and (3)), the thickness control range is usually preferably at an upper and lower limit of ± 0.05 μm, more preferably ± 0.01 μm. As a result, the thickness in the film width direction becomes more uniform, and the thickness variation in the width direction of the film can be 35% or less, preferably 25% or less with respect to the average thickness of the film.

  The film of the present invention is biaxially stretched and heat-treated, and then the film thickness is measured in-line, and the measurement result is fed back to the cap bolt. It is preferable to use an optical interference type as the thickness meter. Further, the film rolled up to 10000 m or more was cut into a predetermined width and length while making the film thickness unevenness in the width direction uniform, and then rolled up on a cylindrical core and the film roll was heated for about 4 to 12 hours at a temperature of 10 After storing in an environment of ~ 35 ° C and letting the air between the film rolls out of the film roll, measure the diameter of the film roll in the width direction and plot the width direction on the X axis and the diameter on the Y axis. The information of R and H read from the measured curve is fed back to the thickness unevenness adjustment at the base, and the maximum and minimum values of the roll diameter in the width direction are rotated by rotating the specific position of the thickness adjusting bolt forward or reverse. The difference R (μm) between the film length L (m) and R ≦ (0.0025 × t1 + 0.0035) × L, and the difference H (μm) between the diameters of both ends of the roll H ≦ (0.0020 × t1 + 0.0030) can be satisfied becomes × L relationship.

Hereinafter, the present invention will be described based on examples.
(1) Inner layer hardness Shore hardness meter (manufactured by Kobunshi Keiki Co., Ltd.) with a weight of 1 kg according to JIS K7312-1996 at intervals of 50 mm in the width direction from the point 2 mm inside from the roll end in the width direction of the film roll. Asker rubber altimeter D type) was measured and the average value was defined as inner layer hardness (h).

  First, the wound film roll is stored at room temperature (25 to 30 ° C.) for 3 hours or longer, then incised and peeled sequentially from the surface layer, and the points of 95% length, 90% length and The average value of the inner layer hardness (h) at the point of 85% length was defined as h3. Similarly, the average value of the inner layer hardness (h) of the 70% long point, the 50% long point, and the 30% long point was defined as h2.

Furthermore, the average value of the inner layer hardness (h) of the 25% long point, 15% long point and 5% long point with respect to the total length of the film was defined as h1.
The measurement at each point was performed within 30 minutes after the incision / peeling.
(2) The difference R (μm) between the maximum value and the minimum value in the width direction of the roll diameter, and the difference H (μm) between the left end diameter and the right end diameter of the roll.
Using a bulk shape measuring device manufactured by Hamano Seiki Co., Ltd., the wound film roll was measured over the entire width 2 mm inside from the end of the roll, and the difference between the maximum value and the minimum value of the diameter was R (μm). The difference in diameter was H (μm).
(3) Air content (%)
It calculated | required with the following formula.
α = (100π × ((d1) ² − (d2) ² ) / (4 × t1 × L)) − 100
α: Air content (%)
t1: Weight method film thickness (μm)
L: Total length of the film wound on the roll (m)
d1: Average value (mm) of roll diameter measured in the above item (2) in the full width direction
d2: Core diameter (mm)
(4) Film surface roughness (central surface average roughness SRa, maximum height SRmax)
Using a three-dimensional surface roughness meter ETB-350K manufactured by Kosaka Laboratory, measurement was carried out under the following conditions using a stylus type.

Stylus tip diameter: 2μmR
Stylus load: 0.04mN
Measurement length: 0.5 mm
Feed pitch: 5μm
Measurement number: 40 Cut-off value: 0.25 mm
When the roughness curved surface f (x, y) is obtained under the above conditions, SRa is obtained by the following equation.

lx: Measurement length = 1 mm, ly: Feed pitch The maximum peak and the deepest valley of the above measurement range are sandwiched between two planes parallel to the average plane, and the interval is defined as the maximum height SRmax.
(5) Film thickness measurement Weight method thickness The weight of the measurement sample was measured, and the density of polyethylene terephthalate was determined to be 1.400 (g / cm ³ ) by the following formula.
t1 (μm) =
Film weight (g) / (film width (m) × film length (m) × density (1.400)
B. Micrometer thickness Using a micrometer, 10 points were measured in the width and length directions of the film, and the average value was used.
(6) Margin accuracy during vacuum deposition, element winding evaluation during capacitor production Using a resistance heating type metal deposition apparatus, the pressure in the vacuum chamber is 10 ⁻² Pa or less, and the surface resistance is 2Ω / □ on one side of the polyester film. Then, aluminum was vacuum-deposited and wound up. At that time, the vapor deposition was performed in a stripe shape having a margin portion running in the longitudinal direction (repetition of a vapor deposition portion width of 8.0 mm and a margin portion width of 1.0 mm).

  The film roll was provided with moisture-proof packaging so that moisture from the outside did not enter after the production until the deposition process was performed. The deposited film obtained as described above was slit into a tape shape with a width of 4.5 mm having a margin part with a width of 0.5 mm on the left or right. At this time, the margin width, which is an undeposited portion, was measured 5 m every 20 cm in the longitudinal direction, and the margin accuracy was evaluated based on the following criteria from the maximum and minimum values of the margin width.

(Margin width range) (Margin accuracy)
0.5 ± 0.15 Super high accuracy ◎
0.5 ± 0.25 High accuracy ○
0.5 ± 0.50 Poor accuracy ×
Each of the obtained left margin and right margin deposited polyester films was wound together to obtain a wound body. At this time, the two films were wound and wound so that the vapor deposition portion protruded by 0.5 mm in the width direction. KAW-4NHB manufactured by Minato Seisakusho was used for element winding. The core material was removed from the wound body, and pressed as it was at 150 ° C. and a temperature and pressure of 10 kg / cm ² for 5 minutes. Metallicon was sprayed on both end faces to form external electrodes, and lead wires were welded to the metallicon to obtain a wound capacitor element.

When manufacturing the above capacitors, visually observe from the beginning of winding to the end of winding, reject wrinkles and misalignment, and indicate the percentage of the number of rejected products as a percentage of the total number of manufactured It was used as an index of property (hereinafter referred to as element winding yield). The higher the element winding yield, the better. 95% or more was evaluated as good ◎, 85% or more and less than 95% as good ◯, and less than 85% as defective x.
(7) Average particle diameter of particles The average particle diameter of the particles was measured with a particle size analyzer (LA-700 manufactured by HORIBA).
(8) Runout of take-up core The inner side of both ends of the core was fixed with a chuck, and the runout when rotating was measured with a dial gauge at the center of each region divided into three equal parts in the width direction.
(9) Cylindricality of take-up core The inside of both ends of the core was fixed with a chuck, the dial gauge was moved in the core width direction, and the difference between the maximum value and the minimum value was defined as cylindricity. The cylindricity may be calculated from a value measured using a bulk shape measuring device in accordance with the above-described measurement in the width direction of the diameter of the roll.
(10) Axial elastic modulus and bending strength of take-up core A load was applied to the center of the core, the axial elastic modulus was determined from the load-deflection ratio, and the bending strength was determined from the breaking load.
(11) Surface roughness of winding core In accordance with JIS B0601-2001, the surface roughness meter Surfcom 111A of Tokyo Seimitsu Co., Ltd. was used, and the centerline average roughness was measured in the width direction at a cutoff of 0.25 mm. The surface roughness was measured at the center of each region divided into three equal parts, and the average value was adopted.
(12) Surface hardness of winding core According to the inspection method of JIS K7215-1986, three-direction measurement was performed with a TYPE D surface hardness meter, and an average value was adopted.
(Example 1)
Polyethylene terephthalate was used as the polyester resin. In the polymerization stage, aggregated silica particles having an average particle size of 1.5 μm were added by a known method so as to be 0.5% by weight per polymer to produce a chip.

  The chip is vacuum dried at 165 ° C., supplied to an extruder, melted at 285 ° C., and then has a pair of lips forming a slit gap, and a plurality of slits arranged along the slit width direction on one lip The sheet was discharged through a die provided with gap adjusting bolts to form a sheet, and cast on a cooling drum having a surface temperature of 25 ° C.

  This film was heated to 108 ° C by simultaneous biaxial stretching of the stenter method, stretched 3.5 times in the longitudinal direction, stretched 3.8 times in the width direction at 108 ° C, and then 2.5% relaxed at 235 ° C. Then, a biaxially stretched film original fabric having a weight method thickness of 1.41 μm and a micro method thickness of 1.55 μm was obtained.

This raw film has a deflection of 0.02 mm, a cylindricity of 0.05 mm, an axial elastic modulus of 14.5 GPa, a bending strength of 210 MPa, a surface roughness of 0.5 μm, a surface hardness of 85, an outer diameter of 167 mm, an inner diameter of A 152.5 mm fiber reinforced plastic (FWP) core A (FWP10 manufactured by Tenryu Kogyo Co., Ltd.) is used with a surface center wind type slitter, slitting speed 170 m / min, initial winding tension 4.5 kg / m, winding core The tension was increased linearly from 10,000 m and increased by 20% at the time of winding. Furthermore, the initial surface pressure at the time of winding was set to 30 kg / m, the surface pressure was increased linearly from 10,000 m, increased by 30% at the time of winding, and a film roll having a width of 500 mm and a length of 18000 m was obtained. After the obtained polyester film roll was stored at 25 ° C. for 5 hours, the inner layer hardness h1, h2, and h3 were measured. As a result, h1 = 94.0, h2 = 93.5, h3 = 93.0 of the obtained film roll. The film surface roughness was SRa = 27.5 nm and SRmax = 1042 nm. The air content was 8.5%.
Furthermore, R which shows the difference of the maximum value of roll diameter of the width direction and minimum value was 40 micrometers, and H which shows the difference of the diameter of the both ends of a roll was 20 micrometers.

Aluminum was vacuum-deposited on one side of a biaxially stretched film obtained from a film roll manufactured under exactly the same conditions as described above, and the deposited film was left or right 0.5 mm wide. The tape was slit into a 4.5 mm width tape having a margin portion, and 70 tape-shaped slit products were collected (hereinafter referred to as reel samples). Then, it wound and obtained the capacitor. The maximum value of the margin width of one reel sample was 0.64 mm, the minimum value was 0.35 mm, and the element winding yield was 98.0%.
(Examples 2-4, Comparative Examples 1-4)
The type and amount of contained particles, film thickness, slit conditions, etc. were changed to obtain a polyester film roll in the same manner as in Example 1. After storing the obtained polyester film roll at 25 ° C. for 5 hours, the inner layer hardness h1, h2, h3 The film surface roughness and air content were evaluated.

  Furthermore, aluminum was vacuum-deposited on the film roll obtained under exactly the same conditions as the production conditions of the evaluation film roll, in the same manner as in Example 1, and then a capacitor was obtained in the same manner as in Example 1 to obtain the margin width and device winding yield. Evaluated. These results are shown in Table 1.

  ADVANTAGE OF THE INVENTION According to this invention, the polyester film roll which solves process problems, such as heat loss and a margin precision, in a capacitor | condenser manufacturing process, and makes it possible to process with high productivity can be provided. The polyester film roll of the present invention is particularly excellent in productivity and processability.

Claims (7)

It is a polyester film roll formed by winding a film around a core, and an inner layer hardness h1 between 5% and 25% length is 90 or more, and an inner layer hardness h2 between 30% and 80% length with respect to the entire length from the raw roll core. A biaxially stretched polyester film roll having an inner layer hardness h3 of 95% or less and 85% to 95% length satisfying the following formula (1), and further having an air content of 5% or more and 25% or less.
0 ≦ (h1-h3) ≦ 5 (1) The difference R (μm) between the maximum value and the minimum value of the roll diameter in the width direction satisfies the formula (2) with respect to the film thickness t1 (μm) and the film length L (m) by the gravimetric method, and The biaxially stretched polyester film roll according to claim 1, wherein a difference in diameter H (μm) between both ends satisfies the formula (3).
R ≦ (0.0025 × t1 + 0.0035) × L (2)
H ≦ (0.0020 × t1 + 0.0030) × L (3) The biaxially stretched polyester film according to claim 1 or 2, wherein a film thickness t1 by a weight method is 0.5 to 3.0 µm. The biaxially stretched polyester film roll according to any one of claims 1 to 3, wherein the film has a surface roughness (central surface average roughness) SRa (nm) of 10 to 100. The biaxially stretched polyester film roll according to any one of claims 1 to 5, wherein the film has a surface roughness (maximum height) SRmax (nm) of 400 to 1800. The biaxially stretched polyester film roll according to any one of claims 1 to 5, wherein a film thickness t1 (µm) by a weight method and a film thickness t2 (µm) by a micrometer method satisfy the formula (4).
0.1 ≦ (t2−t1) ≦ 0.6 (4) It is used for a vapor deposition capacitor, The biaxially stretched polyester film roll in any one of Claims 1-6 characterized by the above-mentioned.