JPH09306780A - Polyester film for capacitor, metallized polyester film for capacitor and film capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester film for a capacitor, superior in film formability, productivity, and various electric characteristics. SOLUTION: The polyester film for a capacitor is a two-axially orientated film of a polyester of a polyethylene terephthalate contg. at least an acid component other than that of terephthalic acid and/or glycol component other than that of ethylene glycol 0.1-10mol%. This improves the film formability i.e., making the film hardly broken and allows a stable film forming for a long time and enables production of very thin films not produced in the prior art, resulting in forming of a polyester film for a capacitor, superior in various electric characteristics (breakdown voltage).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film suitable for a capacitor, and more specifically, it has excellent electrical characteristics and handleability when used as a capacitor, and particularly when used as a thin film or an ultrathin film, the productivity is improved. The present invention relates to an excellent polyester film for capacitors.

[0002]

2. Description of the Related Art Conventionally, as a polyester film for a condenser, Japanese Unexamined Patent Publication (Kokai) No. 2-218726 discloses 4 μm.
There is disclosed an ultrathin film suitable for a capacitor which has a surface shape of m or less, forms a slippery coating film, and is excellent in handleability and film-forming property.

Further, in order to obtain an ultra-thin film, Japanese Patent Laid-Open No.
8-5526, JP-A-58-132520, JP-A-58-136417, JP-A-2-21
It is known from Japanese Patent No. 9648 that a film of different kinds of polymers is laminated and one of them is peeled off to obtain an ultrathin film.

Further, it is possible to use a polyester film prepared by utilizing various copolymerizations of polyethylene terephthalate for use as a film for heat-sensitive stencil printing base paper.
It is known from Japanese Patent No. 166, etc.

[0005]

However, Japanese Patent Application Laid-Open No.
According to Japanese Patent Laid-Open No. 218726, the prevention of tearing (film forming property) is still insufficient in forming a film of a biaxially stretched film. Further, a method of preventing tearing to obtain an ultrathin film while obtaining stable film forming property is disclosed in JP-A-58-5526, JP-A-58-132520, and JP-A-58-136417.
As described in Japanese Patent Laid-Open No. 2-219648 and Japanese Patent Laid-Open No. 2-219648, this method can be expected to have some effect for the purpose, but has a problem such as poor productivity such as a peeling step. Further, in the case of JP-A-6-183166 as a film utilizing copolymerization, it is described that it is used as a film for heat-sensitive stencil, but there is no description for use as a capacitor. Further, since this film has a perforating property and thus contains a large amount of copolymerization components, there is a problem in that when used in a film for a capacitor, various electric characteristics are deteriorated.

An object of the present invention is to provide a polyester film for capacitors, which is excellent in film forming property and productivity and is excellent in various electric characteristics.

[0007]

In order to achieve the above object, the present invention provides a biaxially oriented film having the following constitution, that is, a biaxially oriented film made of polyester, wherein the polyester is terephthalic acid as an acid component. 0.1 to 1 or more glycol components other than ethylene glycol as an acid component and / or glycol component other than ethylene glycol
It is a polyester film for capacitors, characterized by containing 0 mol%.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The polyethylene terephthalate used in the polyester film of the present invention is one in which the dicarboxylic acid component is terephthalic acid and the glycol component is ethylene glycol.

The dicarboxylic acid components other than terephthalic acid in the present invention include isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, adipic acid, trimethyladipic acid, trimellitic acid, pyromellitic acid, Examples thereof include sebacic acid, malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, pimelic acid, azelaic acid, fumaric acid, maleic acid, itaconic acid, dimer acid, cyclohexanedicarboxylic acid and diphenylethanedicarboxylic acid. Especially isophthalic acid, 2,
6-naphthalenedicarboxylic acid, dimer acid, and sebacic acid are preferable from the viewpoint of film-forming property and heat resistance. Examples of glycol components other than ethylene glycol include diethylene glycol, polyethylene glycol, polytetramethylene glycol, propylene glycol, polypropylene glycol, neopentyl glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, Examples thereof include tetramethylene glycol and cyclohexanedimethanol. Among these, as the glycol component, polyethylene glycol, polytetramethylene glycol, neopentyl glycol, and 1,4-butanediol are preferable from the viewpoint of film forming property and heat resistance.

It is desirable that the dicarboxylic acid component other than terephthalic acid and the glycol component other than ethylene glycol in the present invention are copolymerized because the film forming property and the electrical property are excellent.

In the present invention, the content of at least one dicarboxylic acid component other than terephthalic acid and / or glycol component other than ethylene glycol is 0.
It should be 1 to 10 mol%, preferably 0.5 to 5 mol%, more preferably 1 to 3 mol%. 0.1 mol%
If it is less than the following, the film-forming property is inferior and the film tears frequently,
The productivity, that is, the yield, is greatly reduced. On the other hand, if it exceeds 10 mol%, various electrical characteristics are deteriorated and heat resistance is deteriorated, which makes it difficult to use as a polyester film for capacitors.

As a method for obtaining this component, during polymerization,
It may be directly 10 mol% or less, and high concentration, that is,
It may be diluted with polyethylene terephthalate and used when it is charged into an extruder at the time of film formation with a content of more than 10 mol%. In this case, the high-concentration product is preferably 50 mol% or less, more preferably 40 mol% or less, further preferably 30 mol% or less in order to eliminate productivity and quality unevenness.

The thickness of the polyester film of the present invention is 10 μm or less, more preferably 5 μm or less, further preferably 3 μm or less, particularly preferably 1 μm or less. When the thickness exceeds 10 μm, the difference in film formability is small, and the thinner it is, the more remarkable the effect of improving film formability is. Further, when a film is formed by in-line coating, a more remarkable effect is recognized. Further, even in the case of forming a film with the same thickness, in order to improve the productivity, it may be stretched in multiple stages in the longitudinal direction, but in this case also, the effect of improving the film forming property is remarkable, especially in the longitudinal direction. The effect of improving the film-forming property is remarkable when stretched 5 times or more.

Further, M of the polyester film of the present invention
/ P is preferably 0.5 to 4, and more preferably 0.7.
It is preferably in the range of from 3.5 to 3.5 from the viewpoints of electrostatically charged castability, productivity, insulation resistance characteristics, and wet heat resistance characteristics.

The polyester film of the present invention has an intrinsic viscosity [η] of preferably 0.5 dl / g or more, more preferably 0.6 dl / g or more, and even more preferably 0.6.
5 dl / g or more, particularly preferably 0.7 dl / g or more are used in capacitors for withstanding voltage, heat resistance, mechanical properties,
It is preferable from the viewpoint of moisture and heat resistance life characteristics and also from the viewpoint of recoverability.

This polyester film has mechanical properties,
It is necessary to carry out biaxial stretching (orientation) in view of thermal characteristics and electric characteristics.

The maximum surface roughness Rmax of the polyester film of the present invention is preferably 0.1 to 2 μm, more preferably 0.2 to 1.5 μm, and more preferably 0.2.
The range of 5 to 1.2 μm is the improvement of the element winding property of the capacitor and the winding property of the film or metallized film,
It is preferable from the standpoint of improving the withstand voltage, particularly the withstand voltage when loaded at high temperature for a long time.

The surface roughness Ra of the polyester film of the present invention is preferably 0.003 to 0.8 μm, more preferably 0.01 to 0.6 μm, and
It is preferable in terms of winding property, resistance to moisture and heat, improvement of withstand voltage and the like.

The polyester film of the present invention is preferably formed with a coating film containing a polyester resin, a polyester urethane resin, an acrylic resin or the like from the viewpoints of resistance to humidity and heat life and reduction of tan δ.

As the composition of the coating, polyester resins, polyester urethane resins and mixtures thereof are particularly preferable.

This polyester resin can be obtained by polycondensing a dicarboxylic acid component and a glycol component, and as the carboxylic acid component, there are terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid and trimethyladipine. Acid, sebacic acid, malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, pimelic acid, 2,2-dimethylglutaric acid, azelaic acid, fumaric acid, maleic acid, itaconic acid, 1,3-cyclopentanedicarboxylic acid 1,2-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,4-
Examples thereof include naphthalic acid, diphenic acid, 4,4′-oxybenzoic acid, and 2,5-naphthalenedicarboxylic acid. The carboxylic acid may be an acid anhydride, ester, chloride or the like, and examples thereof include dimethyl 1,4-cyclohexanedicarboxylate, dimethyl 2,6-naphthalenedicarboxylate, dimethyl isophthalate, dimethyl terephthalate, diphenyl terephthalate and the like. Is mentioned. Among them, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid and the like are preferable because the water absorption rate can be suppressed to be small, the glass transition temperature can be increased, the increase of tan δ can be suppressed, and the breakdown voltage of the capacitor can be suppressed from decreasing.

As the glycol component, ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 2,4-dimethyl-
2-ethylhexane-1,3-diol, neopentyl glycol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 3-methyl-1 , 5-pentanediol, 2,2,4-trimethyl-1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4 , 4-Tetramethyl-1,3-
Cyclobutanediol, 4,4′-thiodiphenol,
Bisphenol A, 4,4′-methylenediphenol,
4,4 '-(2-norbornylidene) diphenol,
4,4'-dihydroxybiphenol, o-, m-, and p-dihydroxybenzene, 4,4'-isopropylidenephenol, 4,4'-isopropylidenebis (2,6-dichlorophenol), 2,5- Naphthalene diol, p-xylene diol, cyclopentane
1,2-diol, cyclohexane-1,2-diol, cyclohexane-1,4-diol and the like can be mentioned. Among them, ethylene glycol, diethylene glycol, neopentyl glycol and the like are preferable because they can suppress the water absorption rate to be small, and thus suppress the rise of tan δ and the decrease of breakdown voltage of the capacitor.

Further, this polyester resin uses a terminal carboxylic acid as disclosed in Japanese Patent Publication No. Sho 60-23983 in order to obtain the concentration of carboxylic acid on the surface of the polyester film of the present invention. Is not sufficient and preferably has a carboxylic acid in the side chain or pendant. Examples of the polyester resin having a carboxylic acid in its side chain include JP-A-54-46294, JP-A-60-209073, and JP-A-62-2403.
18, JP-A-53-26828, JP-A-5
3-26829, JP-A-53-98336, JP-A-56-116718, JP-A-61-1.
It can be produced from a resin obtained by copolymerizing a polyvalent carboxylic acid having a valence of 3 or more as described in JP-A-24668. Also, other methods may be used.

As the polycarboxylic acid having a valence of 3 or more,
For example, trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, 4-methylcyclohexene-1,2,3-tricarboxylic acid, trimesic acid, 1,
2,3,4-butanetetracarboxylic acid, 1,2,3,4
-Pentanetetracarboxylic acid, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 5, (2,5-dioxotetrahydrofurfuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid, 5- (2,5-dioxotetrahydrofurfuryl) -3-cyclohexene-
1,2-dicarboxylic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, ethylene glycol bistrimellitate,
2,2 ', 3,3'-diphenyltetracarboxylic acid, thiophene-2,3,4,5-tetracarboxylic acid, ethylenetetracarboxylic acid and the like can be mentioned. Among these, particularly preferable one is that when a polyester copolymer is used, the molecular weight decreases with increasing temperature, but the molecular weight increases with decreasing temperature (it does not have to be the original molecular weight), that is, the molecular weight is reversible. It is preferable that the material that changes to 1 is less likely to cause a decrease in melt viscosity during reuse, coloring, gelation of foreign matter, and foaming. Examples of this are 5,
(2,5-dioxotetrahydrofurfuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid and the like can be mentioned.

The polyester resin film is formed by a composite film forming method such as hot melt or melt extrusion, or by a coating method (in-line, in-line, water-soluble and / or water-dispersible using a neutralizing agent such as ammonia or triethylamine).
Offline).

As the polyester urethane resin, Japanese Patent Publication No. 53-38760 and JP-A No. 61-22803.
The water-soluble and / or water-dispersible resins described in JP-A-0 can be mentioned.

The polyester component and the glycol component are the same components as the above-mentioned polyester resin, but the water absorption can be suppressed to be small, and the glass transition temperature can be increased.
It is preferable because the increase of tan δ can be suppressed and the decrease of the breakdown voltage of the capacitor can be suppressed.

As the isocyanate component, tolylene diisocyanate, phenylene diisocyanate, diphenylmethane diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, lysine diisocyanate, isophorone diisocyanate. , Trimethylhexamethylene diisocyanate, cyclohexylene diisocyanate,
Examples thereof include naphthalene diisocyanate and tetrahydronaphthalene diisocyanate. Of these, tolylene diisocyanate is particularly useful in reducing water absorption and tan δ.
Is preferable because

Even in the case of this polyester urethane resin, one having a carboxylic acid in the side chain is preferable in order to obtain a specific surface carboxylic acid concentration. Specific examples thereof include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolvaleric acid. As the manufacturing method, the method described in JP-A-61-228030 is used.

Examples of the acrylic resin of the present invention include alkyl acrylate and alkyl methacrylate.

The resin forming the coating film of the present invention has at least one resin having a glass transition temperature of higher than 60 ° C., more preferably higher than 80 ° C., further preferably 85 to 16 ° C.
0 ° C is a reduction of tan δ and an improvement of withstand voltage, preventing destruction when used as a capacitor, especially reduction of tan δ in high temperature region and low frequency region, improvement of self-healing property, adhesive property, moisture and heat resistance From the standpoint of improving the shape retention of the multilayer capacitor.

In order to obtain this glass transition temperature, in the case of the polyester resin or polyester urethane resin of the above-mentioned coating resin, 2,6-naphthalenedicarboxylic acid, phenylindanedicarboxylic acid, benzophenonedicarboxylic acid, as its dicarboxylic acid component, As the glycol component, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, bisphenol A, dihydroxybenzophenone, xylylene glycol and the like may be appropriately combined and copolymerized, or may be described later. Obtained by a method of copolymerizing a carboxylic acid such as pyromellitic acid, naphthalenetetracarboxylic acid, and 5, (2,5-dioxotetrahydrofurfuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid. From That. It can also be obtained by appropriately combining an acid and a glycol component other than these.

In the polyester film of the present invention, the concentration of carboxylic acid on the surface thereof is preferably 0.003.
Or more, more preferably 0.005 or more, further preferably 0.008 or more, particularly preferably 0.015 to 0.0
7 is preferable from the viewpoints of resistance to moisture and heat, easy adhesion, and recoverability.

The polyester film of the present invention has a water absorption of preferably 0.4 to 3 wt%, more preferably 0.45 to 2.5 wt%, which means that tan δ is reduced.
It is preferable from the viewpoint of improving the dielectric breakdown voltage in a long time under high temperature and high humidity, and preventing a decrease in the winding yield due to a charging phenomenon in winding the capacitor element.

The polyester film of the present invention has a resin resistance (to be described later) of 2 to 5, more preferably 3 to 5 to prevent an increase in resistance at the terminal lead portion and to prevent heat generation. It is preferable from the viewpoint of preventing destruction of the condenser.

It is preferable to add a cross-linking agent such as melamine, epoxy, or isocyanate to the coating agent for the polyester film of the present invention. Of these, cross-linking with an epoxy is preferable because it maintains the wet heat life resistance and is excellent in resin resistance. . Further, an epoxy compound having 2 or more epoxy groups, more preferably 3 to 5 epoxy groups is more preferable as a wet heat life resistance, reduction of tan δ, resin resistance,
It is preferable from the viewpoint of improving the crosslinking rate (excellent in productivity).

The addition amount of this epoxy is 7
Is preferably 30 to 30 parts by weight, and more preferably 10 to 25 parts by weight as resin resistance, and t in the case of a capacitor.
It is preferable in terms of prevention of increase in an δ, resistance to moisture and heat life, prevention of blocking, and the like.

As the curing agent for this epoxy, known curing agents such as diethylenetriamine, triethylenetetramine, benzylmethylamine, metaphenylenediamine, diaminodiphenylmethane, xylylenediamine and ethylmethylimidazole may be used.

When the coating material is a polyester urethane resin, it may be self-crosslinking polyurethane.

This coating layer is, for example, coated with a water-dispersible resin and / or a water-soluble resin of the above-mentioned coating resin before stretching in biaxial stretching film formation or before uniaxial stretching and before biaxial stretching. Obtained by the method, hot melt,
Off-line or in-line coating may be performed using a solvent other than water, and the extrusion may be performed by the melt extrusion method or blending with another resin.

The thickness of the coating layer in the present invention is preferably 0.01 to 5 μm, more preferably 0.02 to 2 μm.
It is preferable from the viewpoints of slipperiness, element winding property, resistance to moisture and heat, resistance to voltage, prevention of corona discharge breakdown, self-healing property, and the like.

Fine particles may be added to the polyester layer or the coating layer of the base material in order to improve the winding property, the slip property of the film and the winding property of the capacitor element. As the particles, any particles such as inorganic particles and organic particles may be added. The inorganic particles may be silica, alumina, zirconia, kaolin, talc, calcium carbonate, calcium phosphate, titanium oxide, etc., and the organic particles may be acrylic acid, styrene, polyester, or the like. And so on. The particle size and the addition amount are determined so as to constitute the above-mentioned maximum roughness and surface roughness.

Next, the method for producing the polyester film for capacitors of the present invention will be explained, but the method is not necessarily limited to this.

First, polyester as a base material is melt extruded by an extruder, cooled on a cooling roll to a temperature below the glass transition point, cast, and heated to the glass transition point or higher, and then 2.8 to 7. 2. Stretched 5 times and further preheated to Tg to 170 ° C. of the base polyester with a stenter, and 3.
It is stretched in the width direction from 0 to 12 times, and relaxed if necessary, and the temperature is lower than the melting point of the base polyester, preferably 235.
It is preferable to heat-set at a temperature not higher than 0 ° C. in order to reduce tan δ.

Next, metal vapor deposition, which becomes an internal electrode in the case of a capacitor, is obtained by a vacuum vapor deposition method, a metal is vapor deposited from an evaporation source, and a vapor deposition film is formed on the polyester film of the present invention. As this evaporation source, resistance heating type boat type, crucible type by radiation or high frequency heating,
There is a method using electron beam heating, but the method is not particularly limited. The metal used for this vapor deposition is Al, Zn, M
Metals such as g and Sn are preferable, but Ti, In, Cr,
Ni, Cu, Pb, Fe, etc. can also be used. These metals preferably have a purity of 99% or more, more preferably 99.5% or more, and are processed into a granular shape, a rod shape, a tablet shape, a wire shape, or a crucible shape.

In the case of this vapor deposition, aluminum is particularly preferable from the viewpoint of productivity and cost, and aluminum is vapor-deposited on at least one side to form an aluminum vapor deposition film. At this time, for example, nickel or copper is simultaneously or sequentially provided with aluminum. Other metal components such as gold, silver, chromium, zinc can also be deposited.

The thickness of the aluminum varies depending on the purpose of use, but is preferably 2 to 100 nm from the viewpoint of the capacitor characteristics, particularly the self-healing property.

Further, in the use as a capacitor, the aluminum oxidation index of the surface of the vapor-deposited aluminum film is preferably 1.65 or less, more preferably 1.45 to 1.45.
1.6 further improves the moist heat resistance.

The polyester film of the present invention is 1
The heat shrinkage ratio at 50 ° C. for 30 minutes is preferably 2% or less, more preferably 1.5% or less, and still more preferably 1% or less in at least the longitudinal direction after forming a capacitor.

[0050]

【Evaluation method】

(1) Intrinsic viscosity [η] of polyester Polyester is dissolved in o-chlorophenol,
Was measured.

(2) Water Absorption Rate Polyester films are piled up and cut into 2 cm square pieces, put into a weighing bottle, and vacuum dried at room temperature for 48 hours.
Let it be 1. This sample was allowed to stand at 60 ° C. and 80% RH, and the weight was measured with time. The weight when the sample became parallel was W2, and the water absorption was determined by the following equation. (W2 is the time when the change in moisture absorption rate is within 10%.) [(W2-W1) / W1] x 100 = water absorption rate (%)

(3) Resin resistance Sample preparation: Aluminum was vapor-deposited on the evaluation surface of the polyester film to be evaluated with a vapor deposition machine so that the surface resistance was 1 to 5 Ω / □ or 20 to 200 nm. This film was cut into a sample having a width of 2 cm and a size of 10 cm to obtain a sample.

Evaluation procedure: A mixture of epoxy resin SR-10 manufactured by Sanyu Resin Co., Ltd. and its curing agent H-330 at a ratio of 100: 80 (weight ratio) was used on the vapor deposition surface of the vapor deposition film in a size of 2 × 2 cm. Apply or drip on the width, and at room temperature 3
After leaving it for 0 min, let it stand for 1 hr in a hot air oven at 105 ° C and observe the surface change of the coating or dropping part. Recognized, one dimension is 1
Marks less than mm are indicated by a triangle, and those exceeding 1 mm are x
It is indicated by a mark.

Then, the above-mentioned evaluation sample was exposed and strongly rubbed to evaluate the adhesion property as follows.

The case where the vapor-deposited layer was not peeled at all was marked as good, and the mark where the extremely slight vapor-deposition was peeled was marked with Δ, and the case where the vapor-deposited layer was peeled completely was marked as unusable.

This evaluation was made into the following 5 grades.

5: Surface: ○, peeling: ○ Good and usable 4: Surface: △, peeling: ○ Slightly problematic, but usable 3: Surface: △, peeling: △ Problematic but can be used 2: Surface: ×, peeling: △ There is a considerable problem, but it can be used depending on the application 1: Surface: ×, peeling: × Cannot be used

(4) Maximum roughness Rmax and surface roughness Ra of the film are measured according to JIS-B0601.

(5) Aluminum Oxidation Index of Aluminum Vapor Deposition Film Surface The vapor deposition film surface is analyzed by soft X-ray photoelectron spectroscopy. If the sample is a condenser, disassemble it and expose the vapor deposition surface to the air to make a sample. From the ratio of the number of atoms obtained by correcting the peak area ratio obtained by the measurement with the relative sensitivity factor of each atom and the component ratio obtained by dividing the peak shifted by the bonding state of each atom, the aluminum oxidation index O
/ Al is calculated by the following equation.

O / Al = [O (Al oxide) / Al
(Total)] / [Al (III) / Al (Total)]

[Al (III) / Al (Total)]
Is Al obtained by dividing the peak of aluminum atom
Abundance ratio of (III), or [O (Al oxide) / Al
(Total)] is calculated by subtracting the oxygen concentration combined with oxygen alone and the elements other than aluminum from the total oxygen concentration with respect to aluminum. That is, for example, the concentration of oxygen bonded to carbon is obtained by dividing the peak of carbon. At this time, when the amount of oxygen cannot be specified, such as when several oxygen-containing functional groups are considered or separation is impossible due to close binding energy, the most oxygen is bonded to carbon. Estimate. Similarly, the amount of bound oxygen is determined for oxygen bound to other elements, and the total value is subtracted from the total oxygen concentration.

The measurement conditions are shown below.

Apparatus: ESCA750 manufactured by Shimadzu Corporation Excited X-ray: MgKα1.2 ray (1253.6 eV) Energy correction: C1S main peak binding energy is 284.6 eV Photoelectron escape angle: 90 degrees

(6) Moisture and heat resistance of the condenser The condenser is kept at 400 ° C. in an atmosphere of 60 ° C. and 95% RH.
VDC was applied, aged, and the capacitance change rate was measured. The time until the capacitance change rate ΔC / C was reduced by 10% was shown as the result of the moisture resistance life test. The longer this time, the better the moist heat resistance. Here, C is the capacitance before aging, and ΔC is the capacitance change before and after aging.

(7) Sheet withstand voltage According to JIS-2110, sheet BDV (dielectric breakdown voltage) was measured. 100μm thickness, 10c on cathode
m square aluminum foil electrode, 25mmφ made of true casting for anode, 500g
It is assumed that the film is sandwiched between the electrodes of the above, and a high voltage DC power supply manufactured by Kasuga is used to boost the voltage at a rate of 100 V / sec to cause dielectric breakdown when a current of 10 mA or more flows. The measurement was performed 30 times, and the average voltage was shown.

(8) High-temperature long-time withstand voltage The capacitor prepared in (9) below is placed in an atmosphere of 105 ° C., 1 hour later, a DC voltage is applied, and a voltage of 25 V is boosted every 5 minutes. When the current of 10 mA or more flowed, it was considered as a breakdown, and this was repeated 5 times to show the highest voltage.

(9) Production of Capacitor Aluminum was vacuum-deposited on one surface of the film so that the surface resistance value was 2Ω. At this time, vapor deposition was performed in a stripe shape having a margin portion running in the longitudinal direction (width of vapor deposition portion: 8.
0 mm, width of the margin part 1.0 mm). Next, a blade was placed at the center of each vapor deposition section and the center of each margin section and slitted to form a take-up reel in the form of a tape having a width of 4.5 mm and a margin of 0.5 mm to the left or right.

The reels having the left margin and the right margin, one by one, were superposed and wound to obtain a wound body having an electrostatic capacity of about 0.047 μF. At that time, the two films were wound while being shifted so that the vapor deposition portion protruded from the margin portion by 0.5 mm in the width direction.

Remove the core material from this wound body and
Pressing was performed at a temperature and pressure of 50 ° C. and 1 MPa for 5 minutes. Metallicon was thermally sprayed on both end faces of this to form external electrodes, and lead wires were welded to the metallicon to obtain a wound-type capacitor element.

(10) Glass transition temperature (Tg) "Robot" DSC RDC manufactured by Seiko Instruments Inc.
220, using SSC5200 HDIS STATION, sample 2 to 5 mg, and heat up at 20 ° C /
It was measured in minutes and determined. If the temperature is not detected by this measurement, raise the temperature to 250 ° C, quench with liquid nitrogen,
The temperature was measured again under the above conditions. In addition, when a glass transition temperature was observed in both, the one that appeared higher was used.

The coating layer was dissolved from the substrate with a solvent, the solvent was removed, only the coating resin was taken out, and when difficult, only the coating layer was scraped to obtain a measurement sample. When the resin of the base material and the coating layer was clear, the material was used as a sample.

(11) Concentration of Carboxylic Acid on the Surface Using ESCA750 manufactured by Shimadzu Corporation, the measurement was carried out under the following conditions.

Excited X-ray: MgKα1,2-ray (1253.6 eV) Photoelectron escape angle θ: 90 ° A polyacrylic acid (PAA) film was used as a standard sample. The following gas phase chemical modification reaction was performed for both the standard sample and the measurement sample.

R-COOH + CF ₃ CH ₂ OH + C ₆ H
₁₁ NCNC ₆ H ₁₁ → R-COOCH ₂ CF ₃ + C ₆ H ₁₁
NHCONHC ₆ H ₁₁

A sample film and a standard sample PAA film were cut into about 1 cm square pieces, and pyridine and dicyclohexylcarbodiimide (DC) were placed in a desiccator under an air atmosphere.
The film surface carboxylic acid was esterified with trifluoroethanol (TFE) using C) as a catalyst (sample film and PAA film were performed in the same batch).

The reaction rate (r) with TFE and the residual rate (m) of DCC used as a reaction catalyst were obtained from the PAA standard sample, and the peak areas of C1S and F1S of each sample were taken into consideration with r and m, and the film surface was considered. Carboxylic acid concentration (-COOH / C [to
tal]).

(12) Element winding property In the above-mentioned capacitor manufacturing method, the element winding-completed product was disassembled before the pressing step, and judged by the meandering state of two films. A meandering of less than 0.5 mm was indicated by と し て as good, and a meandering of 1.0 mm or more was indicated by x as working load. In addition, the intermediate ones are indicated by △.

(13) Sliding property The coefficient of friction was evaluated. AS is a method of evaluating the coefficient of friction.
According to TM-D1894.

(14) Tan delta change rate (δ2-δ1) × 100 / δ1 = tan delta change rate

Sample preparation: diameter 18 for dielectric loss measurement
8 mm sample with aluminum deposited on both sides in a circle
After leaving at 0 ℃ and 80% for 72 hours, 23 ℃ and 65%
The sample left at RH for 10 minutes (dielectric loss δ2 determined by the following measurement) was used. Next, a sample left at 23 ° C. and 65% RH without being left under high temperature and high humidity was used as a comparative sample (dielectric loss δ1 determined by the following measurement).

Measurement: DEA2970 (TA INSTR
Made by UMENTS) at 60 at 23 ° C. and 65% RH
The dielectric loss at Hz was obtained.

(15) Tan δ in a condenser HEWLETT PACKARD LCR meter 4284A.

(16) Casting property In the electrostatically loaded cast, the upper limit of the casting speed at which no surface defect occurs is shown.

(17) M / P M and P represent the residual amount (equivalent amount) of metal (excluding antimony metal) and phosphorus in the polymer, respectively.

M is 700 g of 2 g of polyester in air.
After igniting the polymer by igniting at 2 ° C. for 2 hours, the polymer is dissolved in hydrochloric acid, and the equivalent of metal is determined by an atomic absorption method.

For P, after wet ashing the polyester in the presence of sulfuric acid and perchloric acid, color was developed with ammonium molybdate in an acidic sulfuric acid solution, and the absorbance at 845 nm was measured and quantified by a calibration curve. .

[0087]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

Comparative Examples 1, 2, and 3 Polyethylene terephthalate having an intrinsic viscosity of 0.62 was vacuum dried at 180 ° C. and supplied to the extruder.
After melting at 5 ° C., the sheet was discharged from the T die and cast on a cooling drum.

This film was heated to 90 ° C., stretched 3.5 times in the longitudinal direction, stretched 4 times in the width direction, and subjected to 3.5% relaxation treatment at 215 ° C. to obtain 2 μm, 0.9 μm, 0. 7
A biaxially stretched film of μm was obtained.

Examples 1 to 7 and Comparative Example 4 A copolymer of ethylene terephthalate / ethylene isophthalate of 80/20 mol% having an intrinsic viscosity of 0.62 was added to polyethylene terephthalate at a concentration shown in the table. And a film was formed in the same manner as in Comparative Example 1 to obtain a biaxially stretched film having the thickness shown in the table.

Examples 8 and 9 Biaxially stretched films were obtained in the same manner except that ethylene 2,6-naphthalate was copolymerized instead of the ethylene isophthalate of Example 1.

Example 10 A copolymer consisting of 97/3 mol% of ethylene terephthalate / butylene terephthalate having an intrinsic viscosity of 0.62 was formed into a film in the same manner as in Example 1 to obtain a biaxially stretched film of 0.9 μm. .

[0093]

[Table 1]

[Table 2]

[0094]

EFFECTS OF THE INVENTION The polyester film of the present invention has a film-forming property, that is, a film is less likely to be broken, as compared with a conventional film, and can be stably formed for a long time. This is a polyester film for capacitors which can be produced and is excellent in various electric characteristics (withstand voltage).

Claims (6)

[Claims] 1. A biaxially oriented film made of polyester, wherein the polyester has 0.1 or more of polyethylene glycol terephthalate as an acid component other than terephthalic acid and / or a glycol component other than ethylene glycol as a glycol component. A polyester film for capacitors, characterized by containing 10 to 10 mol%. 2. The polyester film for capacitors according to claim 1, wherein the biaxially oriented film made of polyester has a surface roughness Ra of 0.003 to 0.8 μm. 3. A capacitor, wherein the polyester film for a capacitor according to claim 1 or 2 has a coating film made of a polyester resin, a polyester urethane resin and / or an acrylic resin on at least one surface thereof. Polyester film. 4. The polyester film for capacitors according to claim 3, wherein a cross-linking agent is added to the resin film. 5. A metallized polyester film for capacitors, comprising a metal film formed on at least one surface of the polyester film for capacitors according to any one of claims 1 to 4. 6. A film capacitor comprising the metallized polyester film for a capacitor according to claim 5.