JP4401933B2 - Biaxially oriented laminated polyester film for electrical insulation - Google Patents

Description

  The present invention relates to a biaxially oriented laminated polyester film for electrical insulation, and more specifically, for electrical and electronic members that retain good mechanical properties and electrical insulation even when used under high temperature and high humidity. The present invention relates to a biaxially oriented laminated polyester film.

  Polyester films, especially biaxially stretched films of polyethylene terephthalate and polyethylene naphthalate, have excellent mechanical properties, heat resistance, and chemical resistance. Therefore, magnetic tape, ferromagnetic thin film tape, photographic film, packaging film, electronic parts It is widely used as a material such as a film for electric use, an electrical insulating film, a metal laminating film and a protective film. When used as an electric / electronic member, it is required that the electrical insulation performance does not deteriorate due to a decrease in mechanical properties even when used for a long time at a high temperature. As an electrical insulating material in various fields, a polyethylene terephthalate film is mainly used. However, in applications where the heat resistance of polyethylene terephthalate is insufficient, a polyethylene naphthalate film has recently been used. No. 273844 is disclosed. In applications where high processing characteristics such as motor insulation are required, for example, in JP-A-8-073709, an electrically insulating material in which a specific amount of a thermoplastic elastomer and / or an amorphous polyolefin polymer is mixed with polyester. However, in JP-A-8-073715, in addition to mechanical properties and electrical properties, which are made of a mixture of a polyester having a melting point of 200 to 280 ° C. and an olefin-vinyl alcohol copolymer, it is easy to handle and process. Excellent films are disclosed.

  In recent years, in addition to miniaturization, weight reduction, and high performance of electrical and electronic equipment, applications used in a high temperature and humidity environment are increasing. For example, in applications such as slot liners and wedges for automobile drive motors, the polyester film does not hydrolyze even when used at high temperatures and high humidity. As a result, the mechanical properties and electrical insulation performance deteriorate, resulting in dielectric breakdown. It has been demanded that the characteristics are not impaired.

  In response to such demands, Japanese Patent Application Laid-Open No. 7-118376 discloses a polyester copolymer containing 2,2-alkyl-substituted-1,3-propanediol as a copolymerization component in water and under high temperature and high humidity. It is disclosed that even if it is used, the electrical resistivity is small and the electrical insulating property is low.

  However, as a technique for improving the mechanical properties and electrical insulation properties under high temperature and high humidity while maintaining the excellent heat resistance of the polyester film, a specific copolymer component is added to the polyester as disclosed in JP-A-7-118376. Not only is the method used to modify the polyester itself, but also mechanical properties under high temperature and high humidity conditions such as polyethylene terephthalate homopolymer, polyethylene naphthalate homopolymer, and other polyester films copolymerized with various copolymerization components. In addition, there is a demand for improvement in electrical insulation.

JP 2002-273844 A JP-A-8-073709 Japanese Patent Laid-Open No. 8-073715 Japanese Patent Laid-Open No. 7-118376

  In view of such problems, the object of the present invention is a method that does not depend on polymer modification using a specific copolymer component, is excellent in hydrolysis resistance, and has good mechanical properties and electrical insulation under high temperature and humidity conditions. An object of the present invention is to provide a biaxially oriented laminated polyester film for electrical insulation suitable for electrical and electronic members.

  As a result of intensive studies to solve the above problems, the present inventors have provided a water repellent layer on at least one surface of the polyester film via an anchor layer, and the water contact angle of the surface of the water repellent layer is 90 degrees. As a result, the water-repellent layer prevents the base polyester film from being directly exposed to the high-temperature and high-humidity atmosphere, and the adhesion between the water-repellent layer and the base polyester film is improved through the anchor layer. Since moisture does not penetrate between layers, the hydrolysis resistance of the polyester film is improved, and high mechanical properties and electrical insulation are maintained even when used under high temperature and high humidity, completing the present invention. It came to do.

That is, according to the present invention, the object of the present invention is that an anchor layer and a water repellent layer are sequentially laminated on at least one surface of a polyester film, the anchor layer is a silane anchor layer, and the water repellent layer is made of a silicone resin, This is achieved by a biaxially oriented laminated polyester film for electrical insulation, which is used for a slot liner or wedge of a motor , having a water contact angle of 90 ° or more on the surface of the water repellent layer.

The electrical insulating biaxially oriented laminated polyester film of the present invention includes as its preferred embodiment, as a preferred embodiment that you polyester film composed of polyethylene-2,6-naphthalate.

According to the present invention, a water repellent layer made of a silicone resin is provided on at least one surface of the polyester film via a silane anchor layer, and the water contact angle on the surface of the water repellent layer is 90 degrees or more. A biaxially oriented laminated polyester film for electrical insulation used in motor slot liners or wedges, which has improved hydrolysis resistance and maintains high mechanical properties and electrical insulation even when used at high temperatures and high humidity. The industrial value is extremely high.

The present invention will be described in detail below.
The biaxially oriented polyester laminated film in the present invention has a configuration in which an anchor layer and a water repellent layer are sequentially laminated on at least one surface of a polyester film.

<Polyester resin>
Examples of the polyester resin constituting the polyester film in the present invention include a polymer obtained by polycondensation of a diol and a dicarboxylic acid. Examples of such dicarboxylic acids include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, adipic acid and sebacic acid. Examples of diols include ethylene glycol, 1,4- Butanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, and the dicarboxylic acid component and the diol component are preferably 80 mol% or more, more preferably 90 mol% or more of the total repeating units, respectively. Especially preferably, it is 95 mol% or more. Among these, polyethylene terephthalate and polyethylene-2,6-naphthalate are preferable, and polyethylene-2,6-naphthalate is particularly preferable from the viewpoint of heat resistance.

  The polyester resin in the present invention may be a homopolymer, a copolymer with another polyester, or a mixture with two or more kinds of polyesters. The other component in the copolymer or mixture is preferably 20 mol% or less, more preferably 10 mol% or less, particularly preferably 5 mol% or less, based on the number of moles of the repeating structural unit. As copolymerization components, diol components such as diethylene glycol, neopentyl glycol, polyalkylene glycol, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, etc. Of the dicarboxylic acid component.

  The intrinsic viscosity of the polyester resin in the present invention is preferably 0.40 or more at 35 ° C. in o-chlorophenol, and more preferably 0.40 to 0.80. When the intrinsic viscosity is less than 0.4, the strength of the product after the molding process may be insufficient, or the hydrolyzability under high temperature and humidity may be insufficient. On the other hand, when the intrinsic viscosity exceeds 0.8, the productivity during polymerization decreases.

  The polyester resin in the present invention preferably has a glass transition temperature of 70 to 160 ° C, more preferably 100 to 160 ° C, still more preferably 110 to 155 ° C, and particularly preferably 115 to 150 ° C. When the glass transition temperature of the polyester resin is less than the lower limit, durability at high temperatures may be lowered. On the other hand, when the glass transition temperature of the polyester resin exceeds 160 ° C., workability in the biaxial stretching film forming process may be lowered.

<Lubricant>
In order to improve the handleability of the film in the polyester film of the present invention, a lubricant composed of inert particles may be added as long as the effects of the invention are not impaired. Examples of the inert particles include inorganic particles such as calcium carbonate, silica, talc, and clay, organic particles made of silicone, thermoplastic resin, thermosetting resin, and the like, and pigments such as barium sulfate and titanium oxide alone or in combination. More than seeds may be added.

  Before adding these inert particles to the polyester resin, it is preferable to adjust the particle size and remove coarse particles using a purification process. Examples of industrial means for the production process include a pulverizing means such as a jet mill and a ball mill, and classification means such as a dry or wet centrifuge. Of course, these means may be combined in two or more and purified in stages.

Moreover, various methods can be used as the method of inclusion. The following method can be mentioned as the typical method.
(A) A method of adding before transesterification or esterification reaction at the time of polyester synthesis, or adding before the start of polycondensation reaction.
(A) A method of adding to polyester and melt-kneading.
(C) A master pellet to which a large amount of titanium oxide or other lubricant is added in the methods (a) and (b) above is manufactured, and kneaded with polyester not containing these additives to contain a predetermined amount of additives. Method.

  In addition, when using the method added at the time of the polyester synthesis | combination of said (a), it is preferable to add to a reaction system as a slurry which disperse | distributed titanium oxide and another lubricant to glycol.

  In the polyester film of the present invention, additives such as a heat stabilizer, an antioxidant, an ultraviolet absorber, a mold release agent, a colorant, and an antistatic agent are added to the polyester film of the present invention as long as the purpose of the present invention is not impaired. Can be blended.

  The thickness of the polyester film of the present invention is preferably 1 to 350 μm, more preferably 10 to 300 μm, although it depends on the use.

<Anchor layer>
In the present invention, the anchor layer is provided between the polyester film and the water-repellent layer, so that the adhesion between the polyester film and the water-repellent layer is strengthened, and moisture penetrates between the polyester film and the water-repellent layer. Therefore, the hydrolyzability of the polyester film under high temperature and humidity can be improved, and as a result, the mechanical properties and electrical insulation of the polyester film can be improved. Anchor layer in the present invention, Ru silane anchor layer der consisting silane compound from the viewpoint of adhesiveness. Examples of such silane compounds include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-ureidopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-glycol. Sidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxymethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N- (β-aminoethyl) -γ-aminopropyl Examples include methyldimethoxysilane, N- (β-aminopropyl) -γ-aminopropylmethyldimethoxysilane, and N- (β-aminoethyl) -γ-aminopropyltriethoxysilane. Of these, γ-glycidoxypropyltrimethoxysilane is particularly preferred. 1 type (s) or 2 or more types can be used for this silane compound. The anchor layer may be a silicon oxide film formed from a tetraalkoxysilane and / or a partially hydrolyzed coating solution.

  The anchor layer in the present invention is obtained by applying a water-soluble coating liquid composed of the silane compound described above to at least one surface of a polyester film and then drying it. Examples of the method for forming such an anchor layer include a roll coating method, a gravure coating method, a blade coating method, a screen coating method, a dip coating method, a spin coating method, a spray coating method, and a kiss coating method. Not a thing.

  The thickness of the anchor layer in the present invention is preferably 0.005 to 0.2 μm after drying, and more preferably 0.01 to 0.1 μm. When the thickness of the anchor layer is less than the lower limit, the adhesion function may not be sufficiently exhibited. Moreover, when the thickness of an anchor layer exceeds an upper limit, it may become easy to raise | generate blocking.

<Water repellent layer>
In the present invention, the water repellent layer is laminated on at least one surface of the polyester film via an anchor layer. Water repellent layer in the present invention consists of shea recone resin, such as ultraviolet curable silicone resin or thermosetting silicone resin. Among these silicone resins, thermosetting silicone is particularly preferable, and has a vinyl group, a hydroxyl group, a phenyl group, etc. in a part of the end group and side chain of polydimethylsiloxane, and a catalyst such as platinum or tin oxide is used. Examples include a silicone resin obtained by curing with hydrogensilane having at least one hydrogen atom bonded directly to a silicon atom in one molecule. Further, the silicone resin used in the present invention is at least one selected from the group consisting of D units, T units and Q units represented by the following formula within a range where the water contact angle of the water repellent layer is 90 degrees or more. You may mix | blend the silicone resin which has the structure of.

（式中、Ｒ^１、Ｒ^２、Ｒ^３はそれぞれメチル基またはフェニル基であり、Ｒ¹〜Ｒ^３はそれぞれ同一でも異なっていてもよい。）

(In the formula, R ¹ , R ² and R ³ are each a methyl group or a phenyl group, and R ^{1 to} R ³ may be the same or different.)

  The water repellent layer in the present invention needs to have a water contact angle of 90 ° or more. The water contact angle is preferably 95 degrees or more, more preferably 100 degrees or more. Here, the water contact angle of the water-repellent layer of the present invention means that a sample piece is placed horizontally, the surface on the water-repellent layer side is faced up, and one drop of water is given by a syringe having a capacity of 1 ml according to the JIS R3257 static drop method. This is a value obtained by dripping to form a water droplet of 1 μl or more and 4 μl or less on the sample piece and reading the water contact angle θ after standing for 1 minute with a microscope equipped with an angle measuring device. When such a contact angle is less than the lower limit, the area where water contacts the film is large, and water easily penetrates into the film, so that the hydrolyzability of the polyester film is lowered and the mechanical properties and electrical insulation properties are lowered.

  In order for the water contact angle of the water-repellent layer in the present invention to achieve the above range, the polydimethylsiloxane blending amount in the silicone resin forming the water-repellent layer is preferably 70 mol% or more, more preferably 80. The mol% or more, more preferably 90 mol% or more.

  In the present invention, the water-repellent layer comprises a coating liquid comprising an organic solvent such as toluene, xylene, methyl ethyl ketone, isobutyl ketone and n-hexane and a mixture thereof, the above-mentioned silicone compound and a catalyst, on the side opposite to the polyester film of the anchor layer. After being applied to the surface, it is obtained by drying. Examples of the method for forming such a water-repellent layer include a roll coating method, a gravure coating method, a blade coating method, a screen coating method, a dip coating method, a spin coating method, a spray coating method, and the like. is not.

  The thickness of the water repellent layer in the present invention is preferably 30 to 300 nm after drying, and more preferably 50 to 200 nm. When the thickness of the water-repellent layer is less than the lower limit, the water-repellent function may not be sufficiently exhibited. Moreover, when the thickness of the water-repellent layer exceeds the upper limit, blocking may easily occur.

<Other coating layers>
In order to impart various functions to the laminated polyester film of the present invention, another coating layer may be formed on the surface opposite to the surface on which the anchor layer and the water repellent layer of the polyester film are laminated. Examples of the binder resin that forms such a coating layer include polyester, polyimide, polyamide, polyesteramide, polyvinyl chloride, poly (meth) acrylic ester, polyurethane, polyvinyl chloride, polystyrene, and polyolefin, and copolymers thereof. A blend is mentioned. Of these, polyester, polyimide, poly (meth) acrylic acid ester and polyurethane are preferred. Such a binder resin may be further crosslinked by adding a crosslinking agent. As a solvent for the coating agent, organic solvents such as toluene, ethyl acetate, methyl ethyl ketone, and mixtures thereof can be used, and water may be used as a solvent. The coating film layer of the present invention may further contain a surfactant such as polyalkylene oxide and inert particles as a component for forming the coating film.

<Film formation>
The biaxially oriented laminated polyester film in the present invention can be produced using a conventionally known film forming method such as a tenter method or an inflation method.

  For example, a polyester resin dried in advance is supplied to an extruder heated to 280 to 300 ° C. and molded into a sheet form from a T-die. The sheet-like molded product extruded from the T-die is cooled and solidified with a cooling drum having a surface temperature of 10 to 60 ° C., and this unstretched film is heated by roll heating, infrared heating, etc. Get. Such stretching is preferably performed by utilizing a difference in peripheral speed between two or more rolls. The longitudinal stretching temperature is preferably higher than the glass transition point (Tg) of the polyester resin, and more preferably 20 to 40 ° C. higher than Tg. The longitudinal draw ratio may be appropriately adjusted according to the requirements of the intended use, but is preferably 2.5 times or more and 4.0 times or less, more preferably 2.8 times or more and 3.9 times or less. When the longitudinal draw ratio is 2.5 or less, the thickness unevenness of the film is deteriorated and a good film may not be obtained. Further, when the longitudinal draw ratio is 4.0 times or more, breakage tends to occur during film formation.

  The obtained longitudinally stretched film is subsequently subjected to lateral stretching, heat setting, and thermal relaxation in order to obtain a biaxially oriented film, which are performed while the film is running. The transverse stretching treatment is performed while starting from a temperature 20 ° C. higher than the glass transition point (Tg) of the polyester resin and raising the temperature to a temperature lower by 120 to 30 ° C. than the melting point (Tm) of the polyester resin. The transverse stretching start temperature is preferably (Tg + 40) ° C. or lower. The maximum transverse stretching temperature is preferably (100 to 40) ° C. lower than Tm. When the transverse stretching start temperature is too low, the film is easily broken. When the maximum transverse stretching temperature is lower than (Tm−120) ° C., the thermal shrinkage rate of the obtained film increases, and the uniformity of physical properties in the width direction tends to be lowered. On the other hand, when the maximum transverse stretching temperature is higher than (Tm-30) ° C., the film becomes too soft and the film is easily broken during film formation.

  The temperature increase in the transverse stretching process may be continuous or stepwise (sequential), but usually the temperature is increased sequentially. For example, the transverse stretching zone of the stenter is divided into a plurality along the film running direction, and the temperature is raised by flowing a heating medium of a predetermined temperature for each zone.

  The transverse draw ratio is preferably 2.5 times or more and 4.0 times or less, although it depends on the required characteristics of this application. More preferably, they are 2.8 times or more and 3.9 times or less. If the transverse draw ratio is less than 2.5 times, the thickness unevenness of the film may be deteriorated and a good film may not be obtained. On the other hand, if it exceeds 4.0 times, breakage may easily occur during film formation. is there. The anchor layer is formed by applying an anchor layer coating on at least one surface of the uniaxially stretched film.

  The biaxially stretched film is then heat set. Furthermore, on the anchor layer of the obtained biaxially oriented polyester film after the heat setting treatment, a water repellent layer is provided by applying a coating made of a silicone resin, followed by heat drying at 150 ° C. for 20 seconds. A water repellent layer having a thickness of 30 to 300 nm is formed.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited only to these Examples. Each characteristic value was measured by the following method. Moreover, unless otherwise indicated, the part and% in an Example mean a weight part and weight%, respectively.

1. Contact angle The contact angle was measured by placing a flat sample piece horizontally, with the water repellent layer side facing up, and dropping one drop of water with a 1 ml syringe in accordance with the JIS R3257 static drop method. A water droplet of 1 μl or more and 4 μl or less was allowed to stand on the sample piece. The water contact angle θ after standing for 1 minute was then read with a microscope equipped with an angle measuring device.

2. Adhesion of water repellent layer
A test piece (50 mm × 50 mm) was placed in a constant temperature and humidity chamber at 60 ° C. and 80% RH for 1 week, then removed, and the surface on the water repellent layer side was rubbed 10 times with a finger, and the adhesion was evaluated according to the following criteria.
○ With water-repellent layer peeling × Without water-repellent layer peeling

3. Hydrolysis resistance A strip-shaped sample piece 100 mm long × 5 mm wide is suspended with a stainless steel clip in an environmental tester set to 121 ° C., 2 atm, wet saturation mode, and 100% RH. After 750 hours, the film was taken out from the environmental testing machine, allowed to stand at 23 ° C. for 24 hours, and then the tensile stress was measured at a distance between chucks of 50 mm and a tensile speed of 100 mm / min using an orientec Tensilon UCT-100 type. The strength retention rate after 750 hours was calculated according to the formula. The measurement was performed 5 times, and the hydrolysis resistance was determined from the average value according to the following criteria.
Strength retention (%) = (tensile stress after 750 hours / initial tensile stress) × 100
○: Strength retention 50% or more Δ: Strength retention 25% or more ×: Strength retention less than 25%

4). Dielectric breakdown strength In accordance with the plate electrode method described in JIS C2151, the voltage was increased at a speed of 1 (KV / sec) using ITS-6003 manufactured by Tokyo Seiden Co., Ltd. Read breakdown voltage was measured. The measurement was carried out using a biaxially oriented laminated polyester film, and it was treated for 750 hours in an environmental tester set to an initial breakdown voltage and 121 ° C. · 2 atm · wet saturation mode · 100% RH, and then at 23 ° C. The dielectric breakdown voltage after standing for 24 hours was measured.
○: Dielectric breakdown voltage 20 kV or more △: Dielectric breakdown voltage 10 kV or more ×: Dielectric breakdown voltage less than 10 kV

[Example 1]
Calcium carbonate having an average particle size of 0.5 μm as a lubricant, using 100 parts by weight of naphthalene-2,6-dicarboxylic acid dimethyl ester, 60 parts by weight of ethylene glycol, 0.03 parts by weight of manganese acetate tetrahydrate as a transesterification catalyst Adding 0.25 wt% of particles, 0.06 wt% of spherical silica particles having an average particle size of 0.2 µm, and 0.1 wt% of spherical silica particles having an average particle size of 0.1 µm; After transesterification according to a conventional method, 0.042 parts by weight of triethylphosphonoacetate was added to substantially complete the transesterification reaction. Subsequently, 0.024 parts by weight of antimony trioxide was added, and subsequently polymerization reaction was carried out by a conventional method at high temperature and high vacuum to obtain polyethylene-2,6-naphthalenedicarboxylate (PEN) having an intrinsic viscosity of 0.60 dl / g. Tg = 121 ° C.).

  The PEN polymer was dried at 175 ° C. for 5 hours, then supplied to an extruder, melted at a melting temperature of 300 ° C., extruded through a die slit, cooled and solidified on a casting drum set at a surface temperature of 55 ° C. A stretched film was prepared.

  This unstretched film is stretched 3.0 times in the longitudinal direction (longitudinal direction) at 140 ° C., and an aqueous solution containing γ-glycidoxypropyltrimethoxysilane as an anchor layer is kiss coated on both sides of the uniaxially stretched polyester film. Then, it is biaxially stretched by 2.8 times in the transverse direction (width direction) at 140 ° C. and then heat-fixed for 10 seconds at a heat fixing temperature of 250 ° C., and the anchor layer after drying A biaxially oriented polyester film having a thickness of 0.08 μm and a total thickness of 250 μm was obtained and wound on a roll.

On the anchor layer of the obtained biaxially oriented polyester film, an addition reaction type silicone comprising polyalkylalkenylsiloxane and a silicone solution containing polyalkylhydrogensiloxane as a coating liquid for forming a water-repellent layer [Toshiba Silicone Co., Ltd. Trade name TPR-6700] 100 parts by weight of a platinum compound curing agent [Toshiba Silicone Co., Ltd. trade name CM-670] 2 parts by weight, diluted with a solvent of methyl ethyl ketone (MEK) and toluene, solid content 2% A solution prepared by applying a bar coater on both sides of the solution and drying for 1 minute with a drier at 140 ° C., and the thickness of the water-repellent layer after drying made of thermosetting silicone is 0. A water repellent layer having a thickness of 0.05 to 0.1 μm was formed.
Table 1 shows the characteristics of the obtained biaxially oriented laminated polyester film. The contact angle of water was measured with the surface when the laminated polyester film was rolled up as a surface and the back surface as the b surface. The film of this example had sufficient adhesiveness of the water-repellent layer, and was excellent in hydrolyzability and electrical insulation.

[Example 2]
As a coating liquid for forming a water-repellent layer, a condensation reaction type silicone made of polyalkylsiloxane and a silicone solution containing polyalkylhydrogensiloxane [Toshiba Silicone Co., Ltd., trade name YSR-3022] 100 parts by weight cured with a dialkyltin compound Biaxial in the same manner as in Example 1 except that 5 parts by weight of the agent [Toshiba Silicone Co., Ltd., trade name YC-6831] was added and diluted with a solvent of MEK, methyl isobutyl ketone and xylene to give a 2% solids solution. An oriented laminated polyester film was obtained.
Table 1 shows the characteristics of the obtained biaxially oriented laminated polyester film. The film of this example had sufficient adhesiveness of the water-repellent layer, and was excellent in hydrolyzability and electrical insulation.

[Example 3]
In the same manner as in Example 1, a biaxially oriented polyethylene-2,6-naphthalate film was obtained, and the same kind of coating material as in Example 1 was applied to one side of the film as an anchor layer of the same kind as in Example 1. The film was applied to one surface of the film by a kiss coating method, and then stretched in the transverse direction and heat-fixed by the same method as in Example 1. A water-repellent layer was further formed on one side of the obtained biaxially oriented polyester film on which the anchor layer was formed by the same method as in Example 1 to obtain a biaxially oriented laminated polyester film. Further, on the surface on which the anchor layer and the water repellent layer are not formed, a hardener [Arakawa Chemical Co., Ltd. trade name Composeran E103] 20 comprising 49.8 parts of epoxy resin [Arakawa Chemical Co., Ltd. trade name Composeran AD01] 20 The coating was applied using a bar coater so that the film thickness after drying was 1.0 to 20.0 μm, and was pressed onto a metal plate (iron).

  The initial tensile stress, which is an evaluation of hydrolysis resistance, was measured by dissolving the metal plate portion of the sample on which the metal plate was pressure-bonded with hydrochloric acid, washing the obtained biaxially oriented laminated polyester film with water, and then washing at 23 ° C. for 24 hours. It went after leaving. Evaluation of hydrolysis resistance at the time of 750 hours passed performed the hydrolysis treatment for 750 hours using the sample which pressure-bonded the metal plate, Then, after removing the metal plate according to the above-mentioned method, the tensile stress was measured. Evaluation of the contact angle and the adhesiveness of the water-repellent layer was performed using a biaxially oriented laminated polyester film. The obtained characteristics are shown in Table 1. The film of this example had sufficient water-repellent layer adhesion and excellent hydrolyzability.

[Comparative Example 1]
A biaxially oriented polyethylene-2,6-naphthalate film was obtained in the same manner as in Example 1 except that the anchor layer and the water repellent layer were not formed. Table 1 shows the characteristics of the obtained biaxially oriented polyethylene-2,6-naphthalate film. The film of this comparative example has insufficient water repellency because the water contact angle is less than 90 degrees, sufficient hydrolyzability cannot be obtained, and dielectric breakdown strength after long-term high-temperature and high-humidity treatment is also reduced. did.

[Comparative Example 2]
A biaxially oriented polyethylene-2,6-naphthalate film laminate having a water-repellent layer on both sides of a biaxially oriented polyethylene-2,6-naphthalate film was prepared in the same manner as in Example 1 except that no anchor layer was formed. Obtained. Table 1 shows the characteristics of the obtained biaxially oriented polyethylene-2,6-naphthalate film laminate. Since the film of this comparative example had insufficient adhesion to the polyester film of the water repellent layer, sufficient hydrolyzability was not obtained, and the dielectric breakdown strength after long-term high-temperature and high-humidity treatment was also reduced.

  Since the biaxially oriented laminated polyester film obtained by the present invention has good electrical insulation and excellent hydrolysis resistance under high temperature and humidity, it can be used for electrical insulation suitable for electrical and electronic members. In particular, it is preferably used for a slot liner or wedge of a motor.

Claims (2)

An anchor layer and a water repellent layer are sequentially laminated on at least one surface of the polyester film, the anchor layer is made of a silane anchor layer, the water repellent layer is made of a silicone resin, and the water contact angle on the surface of the water repellent layer is 90 degrees or more. A biaxially oriented laminated polyester film for electrical insulation, which is used for a slot liner or wedge of a motor .   The biaxially oriented laminated polyester film for electrical insulation according to claim 1, wherein the polyester film is made of polyethylene-2,6-naphthalate.