JP2014225389A - Electric insulation paper, electric insulator obtained by heating the paper and electric motor or transformer having electric insulation space - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electric insulation paper which reaches details of a narrow space requiring electric insulation, allows filling of a narrow space requiring electric insulation with an insulation member, has high adhesiveness to conductive members requiring electric insulation, is excellent in electric insulation and heat resistance, shows an oil resistance and is also usable in applications of motor interphase insulation.SOLUTION: In electric insulation paper, a thermal-expansion insulation layer containing a thermally expandable functional resin fine particles is arranged on one or both sides of a paper-like substrate. The functional resin particles are thermally expandable microcapsules which are composed of an outer shell made of a thermoplastic polymer of an average particle size of 5-50 μm and a film thickness of 2-15 μm and a low-boiling-point hydrocarbon included in the outer shell, with the boiling point of the low-boiling-point hydrocarbon being equal to or lower than the softening temperature of the thermoplastic polymer. An electric insulator obtained by laminating the electric insulation paper on a member and heating and an electric motor and a transformer having an electric insulation space obtained by heating the electric insulation paper are also provided.

Description

  The present invention relates to an electrical insulating paper used for electrical and electronic parts, and more particularly to an electrical insulating paper having excellent electrical insulation and heat resistance, and having a gap filling function in a narrow space, and insulating between phases of an electric motor and a transformer. The present invention relates to electrical insulating paper that can also be used for applications.

  In transformers and electric motors, an insulating member is installed between the coils (between phases) and between the coil wire and the core material such as an iron core in order to prevent discharge or short circuit due to a potential difference. In addition to electrical insulation, heat resistance against heat generated by energization is required.

In recent years, the shift from fuel engines to electric motors is accelerating in accordance with the global trend of global environmental conservation symbolized by global warming and depletion of fossil fuels associated with the generation of greenhouse gases. Inevitably, the pursuit of miniaturization, high output, and high efficiency of electric motors is in progress, and electric motor drive by inverter control at high voltage is also an important technology for that purpose. In designing an electric motor, it is possible to increase the electric energy conversion efficiency by increasing the coil occupancy in the electric motor, and to increase the voltage applied to the inverter, and to increase the output. Increasing the coil occupation ratio leads to a narrow and thin space occupied by the insulating member for electrical insulation. High voltage means that the insulation member prevents intrusion of high surge voltage generated from the inverter, heat resistance against heat generated by the high voltage, and reliable electrical insulation in a narrow insulation space. It is required to secure. In general, as such an insulating member, an insulating member having an electrical insulating property such as a high heat-resistant resin, paper, ceramics, oil or the like is used alone or in combination depending on the application. (For example, refer to Patent Documents 1 and 2). Furthermore, as an insulating paper that can be used at a temperature such that the internal temperature of the electric motor exceeds 150 ° C., a paper using a heat-resistant adhesive has been studied (for example, see Patent Document 3). In addition, an insulating sheet in which a porous resin layer containing a thermoplastic resin is formed in advance from the viewpoint of preventing a surge voltage from entering with a low dielectric material has been proposed (see, for example, Patent Document 4).
In addition, a hybrid car or an electric vehicle is equipped with a motor generator that selectively functions as an electric motor and a generator. A method of circulating cooling oil inside the motor generator in order to maintain the performance is known from Japanese Patent Application Laid-Open No. 2006-081240. Insulating members for this type of oil immersion motor need to have excellent oil resistance.
Conventionally, as such an insulating member for an electric motor, in order to ensure required properties such as predetermined strength and dielectric breakdown voltage, a laminate in which a plurality of sheet materials having different properties are bonded and laminated with an adhesive or the like A sheet is used. For example, a laminate in which heat-resistant paper is laminated on both surfaces of a polyester film via a urethane-based or acrylic-based room temperature curing type or thermosetting adhesive has been studied (for example, see Patent Document 5).
As described above, there is a demand for an insulating member that can reliably obtain electrical insulation performance in a high-temperature and narrow space because of demands for miniaturization and high efficiency of electric energy conversion.

Japanese Patent Laid-Open No. 9-23601 JP 2006-321183 A JP 2008-178197 A JP 2012-182116 A JP 2006-262687 A

  In order to ensure electrical insulation performance at high temperature and in a narrow space in each part of a conductive member that requires electrical insulation, such as transformers, electric motors, other various electrical products, coils and core materials in electronic products, It is necessary to reliably fill the narrow space with the insulating member. In the case of using the conventional various insulating members, in the manufacturing method incorporating the insulating member, a method of assembling while alternately sandwiching conductive members and insulating members that require electrical insulation such as coils and core materials, and uninsulated There is a method in which an insulating process is performed later on the conductive member assembled while leaving the part.

  In the former method of assembling while alternately sandwiching the conductive member and the insulating member, a process for ensuring electrical insulation is necessary in each assembly process, which requires a lot of man-hours and takes time.

  As a method of performing an insulation treatment on the latter assembled conductive member later, a heat-resistant resin is selected as an insulating member, and a raw material of the resin is poured into a space where electrical insulation is required to solidify or cross-link. There are a method of curing by, a method of selecting a sheet-like insulating member, and inserting and fixing it in a space that requires electrical insulation. When a heat-resistant resin is selected, the process of reliably pouring and filling the resin raw material is difficult, and in addition to the filling process, a solidification or curing reaction process is sequentially performed. It has been a factor that hinders efficient production of various electric products and electronic products, such as requiring standing time including processes. In addition, when a sheet-like insulating member is selected, if the sheet-like insulating member is a resin film, it may not be possible to reach the details of a narrow space that requires electrical insulation due to poor flexibility, or may have a multilayer structure. If it is a composite sheet, it is too thick to be inserted into a narrow space where electrical insulation is necessary, or a narrow space where electrical insulation is necessary cannot be filled with an insulating member, or electrical conductivity that requires electrical insulation. There is a problem that the electrical insulation is impaired due to insufficient adhesion to the conductive member.

  Accordingly, an object of the present invention is to provide an electrical insulating paper as a sheet-like insulating member that solves the above-described problems. Specifically, in various electrical products and electronic products, it can reach the details of a narrow space that requires electrical insulation, and the narrow space that requires electrical insulation can be filled with an insulating member, and the electrical conductivity that requires electrical insulation is required. Another object of the present invention is to provide an electrical insulating paper that has high adhesion to a conductive member, is excellent in electrical insulation and heat resistance, has oil resistance, and can be used for motor phase insulation.

As a result of intensive studies, the present invention has solved the above problems with the following technical configuration.
(1) An electrically insulating paper characterized in that a thermally expandable insulating layer containing thermally expandable functional resin fine particles is disposed on one side or both sides of a paper-like material.
(2) The functional resin fine particles are composed of an outer shell made of a thermoplastic polymer having an average particle diameter of 5 to 50 μm and a film thickness of 2 to 15 μm, and a low-boiling hydrocarbon encapsulated in the outer shell, The electrically insulating paper according to (1), wherein the low-boiling hydrocarbon is a thermally expandable microcapsule having a boiling point equal to or lower than a softening temperature of the thermoplastic polymer.
(3) An electrical insulator obtained by laminating the electrical insulating paper according to either (1) or (2) on a member and then heating.
(4) An electric motor or transformer having an electrically insulating space obtained by heating the electrically insulating paper described in (1).

When using the electrical insulating paper of the present invention, in the manufacture of each part of a conductive member that requires electrical insulation, such as a transformer, an electric motor, other various electrical products, coils, and core materials in electronic products, Since it is possible to employ a method of performing an insulation process on the conductive member assembled as it is left behind, a process for securing electrical insulation is not required in each assembly process, and the number of steps can be reduced.
Since the electrical insulating paper of the present invention is made of a flexible paper-like material, it can be flexible and thinned. As a result, various electrical products and electronic products require narrow electrical insulation. It is possible to reach the details of the space.
The electrically insulating paper of the present invention has a function of filling the gap in a narrow space by heat-expanding functional resin fine particles arranged on the surface, and has a gap filling function in a narrow space. It is possible to form an electrically insulating space filled with a member and to increase the adhesion to a conductive member that requires electrical insulation. Furthermore, a plurality of conductive members that require electrical insulation can be bonded and fixed in a state where the electrical insulation space is formed without changing their three-dimensional positional relationship.
Since the electrical insulation space obtained by heating the electrical insulation paper of the present invention is excellent in electrical insulation and heat resistance and has oil resistance, it can be used as an interphase insulation application for electric motors and transformers.

It is sectional drawing about one Embodiment of the electrical insulation paper of this invention. It is the schematic explaining the electrical insulation process of the coil wire and core material of an electric motor using the electrical insulation paper of this invention.

Embodiments of the present invention will be described below.
<Electrical insulation paper>
The electrical insulating paper of the present invention will be described with reference to FIG. In the electrical insulating paper of the present invention, a thermally expandable insulating layer 2 is disposed on one side (a) or both sides (b) of a paper-like material 1 impregnated or encapsulated with a heat resistant resin.

(Paper)
As the paper-like material, papermaking paper and non-woven fabric obtained by forming various fiber materials into sheets by a known method using a wet method or a dry method can be used. The thickness of the paper-like material is not particularly limited as long as it can be appropriately designed according to the size of the space where the electrical insulation to be applied is necessary, and a general paper-making paper and non-woven fabric can be produced.
As the fiber material of the paper-like material constituting the electrical insulating paper of the present invention, chemical pulp (conifer bleached kraft pulp (NBKP) or unbleached kraft pulp (NUKB), hardwood bleached kraft pulp (LBKP) or unbleached kraft pulp (LUKP, etc.), cellulose components such as mechanical pulp (grand pulp (GP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), etc.), non-wood pulp such as kenaf, hemp, bamboo, glass Chemical fibers such as fibers, polyethylene, polyester fibers, and ceramic fibers, ceramic fibers, various engineering plastics, and various fluorine-based resins can be used alone or in admixture at any ratio. Moreover, it is also possible to grind | pulverize and mix | blend these fiber materials as needed.

  Examples of the engineering plastic and fluororesin include, for example, polyacetal, polyamide, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, glass fiber reinforced polyethylene terephthalate, ultrahigh molecular weight polyethylene, syndiotactic polystyrene, amorphous polyarylate, polysulfone, polysulfone. Ether sulfone, polyphenylene sulfide, polyether ether ketone, polyimide, polyether imide, fluorine resin, liquid crystal polymer, polytetrafluoroethylene, partially fluorinated resin, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, perfluoro Alkoxy fluoropolymer, ethylene tetrafluoride / hexafluoropropylene copolymer, ethylene / tetrafluoroethylene copolymer Combined, and an ethylene-chlorotrifluoroethylene copolymer.

  When producing paper-like material by wet papermaking, it is essential that the pulp beating degree be 400 to 600 ml in Canadian standard freeness. When the freeness exceeds 600 ml, the bond strength between the pulp fibers forming the paper layer is significantly weakened, and the tensile strength, interlaminar strength, and burst strength are reduced, causing breakage and breakage during processing. It becomes easy. Also, when the Canadian standard freeness is less than 400 ml, when forming and processing, it becomes easy for cracks to occur on the surface of the paper layer at the folded part, and the density of the paper becomes high. In order to obtain it, it is necessary to increase the basis weight, which increases the cost. Furthermore, flexibility becomes low and workability deteriorates.

  In the present invention, it is preferable that the paper-like material contains a heat-resistant stabilizer. By adding a heat stabilizer to the paper, the oxidative deterioration of the paper is suppressed, thereby improving the heat resistance. As a heat-resistant stabilizer, it is preferable to appropriately add an antioxidant, a photo-antioxidant, an ultraviolet absorber, a light shielding agent, a quencher, or the like as a component for preventing oxidative deterioration of the paper-like material by heat or light. For example, as the antioxidant, phenolic, phosphorus, sulfur and amine antioxidants can be used, and amine compounds such as dicyandiamide are particularly preferably used. By using an amine-added paper, the heat resistance of the pulp is improved. Although the addition amount of a heat-resistant stabilizer is a suitable design matter, it is a mass ratio of about 1-20 with respect to the dry mass 100 of a pulp, for example. The heat-resistant stabilizer can be mixed in the papermaking pulp slurry or contained in the paper layer by using a size press.

  Furthermore, the electrical insulating paper of the present invention includes sizing agents, paper strength enhancing agents, fixing agents, yield improving agents, internal additives such as dyes, calcium carbonate, kaolin, talc, hydroxylation, as long as the quality is not affected. An internal filler such as aluminum can be used.

  When the paper-like material is produced by wet papermaking, the type of the paper machine is not particularly limited.For example, the paper machine is made using a paper machine such as a round net type, a long net type, a short net type, or an inclined net type. A paper-like product can be produced by drying with a Yankee dryer, rotary dryer, band dryer or the like. The press line pressure is used within the normal operating range. The surface treatment agent may or may not be applied. When the surface treatment agent is applied, there is no particular limitation on the components of the surface treatment agent, and the type of size press is also not limited, and a liquid film such as a two roll size press, a gate roll size press, or a rod metalling size press. A transfer size press or the like can be used as appropriate.

  The surface treatment agent is not particularly limited, for example, raw starch, oxidized starch, esterified starch, cationized starch, enzyme-modified starch, aldehyde-modified starch, modified starch such as hydroxyethylated starch, carboxymethylcellulose, hydroxyethylcellulose, Cellulose derivatives such as methylcellulose, modified alcohols such as polyvinyl alcohol and carboxyl-modified polyvinyl alcohol, styrene butadiene copolymer, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, polyacrylic acid ester, Polyacrylamide can be used alone or in combination.

  It does not matter whether or not the paper layer is coated, but when providing a coating layer, heavy calcium carbonate, light calcium carbonate, kaolin, talc, mica, titanium oxide, white carbon, satin white, calcium sulfate, Inorganic pigments such as barium sulfate, gypsum, aluminum hydroxide, calcined kaolin, delaminated kaolin, magnesium carbonate, zinc oxide, calcium sulfite, magnesium hydroxide, and magnesium oxide, and organic pigments such as plastic pigments can be used as appropriate. Preferably, the insulating property can be further improved by incorporating an inorganic pigment such as light calcium carbonate, kaolin, or mica in the coating layer. The additive used when the coating layer is provided on the paper layer is not particularly limited, and auxiliary agents such as a binder, a dispersant, a water retention agent, and an antifoaming agent can be appropriately used.

  As a method of providing a coating layer on a paper-like material, a known coating machine such as a blade coater, an air knife coater, a roll coater, a comma coater, a brush coater, a kiss coater, a curtain coater, a bar coater, a gravure coater, a die coater is used The method can be selected as appropriate.

  After coating, the coated layer is dried to obtain coated paper. As a drying method, for example, a normal method such as a steam heater, a gas heater, an infrared heater, an electric heater, a hot air heater, a microwave, or a cylinder dryer can be adopted, and after drying, post-processing is performed as necessary. Smoothness can be imparted by a finishing process such as a super calender or soft calender. In addition, any other general paper processing method can be applied.

(Impregnated resin)
As the resin impregnated or encapsulated in the paper-like material, a crosslinkable polymer such as phenol resin, epoxy resin, unsaturated polyester, rubber component, and various thermoplastic resins can be used. The rubber composition includes natural rubber, isoprene rubber (IR), butadiene rubber (BR), styrene / butadiene rubber (SBR), chloroprene rubber (CR), nitrile rubber (NBR), polyisobutylene (butyl rubber IIR), ethylene propylene. Rubber (EPM, EPDM), chlorosulfonated polyethylene (CSM), acrylic rubber (ACM), fluorine rubber (FKM), epichlorohydrin rubber (CO, ECO), urethane rubber (U), silicone rubber (Q), etc. . By adding a rubber component, flexibility can be imparted to the paper-like material. Although it does not specifically limit as said thermoplastic resin, It is preferable that it is a thermoplastic resin which has heat resistance, and the glass transition temperature is 150 degreeC or more especially, and what has heat resistance of 180 degreeC or more is used suitably. . Examples of such thermoplastic resins include polyamide, polycarbonate, polybutylene terephthalate, polyethylene terephthalate, polyphenylene sulfide, polyarylate, polysulfone, polyethersulfone, polyetheretherketone, polyamideimide, polyimide, polyetherimide, various acrylic resins, Examples include liquid crystal polymers. The resin impregnated or included in the paper-like material can be used alone or in combination of two or more.

(Thermally expandable functional resin fine particles)
Thermally expandable functional resin fine particles are fine particles having the property of irreversibly volume-expanding by external heating. The thermally expandable functional resin fine particles are composed of an outer shell made of a thermoplastic polymer and a low-boiling hydrocarbon encapsulated in the outer shell, and the boiling point of the low-boiling hydrocarbon softens the thermoplastic polymer. It is preferably a thermally expandable microcapsule having a temperature or lower. The average particle diameter of the outer shell made of the thermoplastic polymer is preferably 5 to 50 μm, more preferably 20 to 45 μm, further preferably 25 to 40, and the film thickness of the outer shell is preferably 2 to 15 μm. If the average particle size exceeds 50 μm, the encapsulated material may rupture at the time of heat expansion and the inclusions may leak out. If this happens, the heat resistance and electrical insulation properties may be impaired. If the average particle size is less than 5 μm, there is a possibility that sufficient expansion cannot be obtained, and since the gap filling function in a narrow space becomes insufficient, it is not possible to fill a narrow space that requires electrical insulation with an insulating member, Adhesion with a conductive member that requires electrical insulation may be insufficient, and electrical insulation characteristics may be impaired.

  The thermoplastic polymer that constitutes the outer shell of the thermally expandable functional resin fine particles must not inhibit the expansion of the microcapsule while preventing the inclusions that are softened and expanded by heating to escape and leak, The softening temperature is preferably 100 ° C. or higher, more preferably 120 to 250 ° C., and more preferably 150 ° C. to 200 ° C. Below 100 ° C., it cannot withstand the heat generation of the motor and is not suitable as an electrical insulating member. Above 250 ° C., it is not realistic because the heat resistance of other members constituting the motor or the like becomes a problem in the process of heating to obtain an electrically insulating space. The material constituting the outer shell is not particularly limited as long as it is such a thermoplastic polymer, but in order to obtain a high coefficient of thermal expansion, vinylidene chloride-acrylonitrile, vinylidene chloride-acrylonitrile-methyl acrylate, vinylidene chloride is used. Particularly preferred are acrylonitrile, ethyl acrylate, vinylidene chloride-acrylonitrile-methyl methacrylate, vinylidene chloride-acrylonitrile-vinyl acetate, vinylidene chloride-methyl methacrylate, acrylonitrile-methyl methacrylate-acrylonitrile-vinyl acetate copolymer resins. Further, from the viewpoint of heat resistance and electrical insulation, an acrylonitrile-based copolymer is more preferable.

  As the acrylonitrile-based copolymer, those using 80% by weight or more of a nitrile monomer as a monomer component are particularly preferable. As the nitrile monomer, acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile are used. , Fumaronitrile, any mixture thereof and the like are exemplified, and acrylonitrile and / or methacrylonitrile are particularly preferable. Examples of the non-nitrile monomer include methacrylic acid ester, acrylic acid ester, styrene, vinyl acetate, vinyl chloride, vinylidene chloride, butadiene, vinyl pyridine, α-methylstyrene, chloroprene, neoprene, and any mixture thereof. Particularly preferred are methyl methacrylate, ethyl methacrylate, and methyl acrylate.

  The amount of the non-nitrile monomer used as the monomer component in the acrylonitrile copolymer is 20% by weight or less. Further, a crosslinking agent may be added, for example, divinylbenzene, ethylene dimethacrylate, glycol, triethylene glycol dimethacrylate, triacryl formal, trimethylolpropane trimethacrylate, allyl methacrylate, 1,3-dimethacrylic acid 1,3- Examples thereof include butyl glycol and triallyl isocyanate, but 0 to 1% by weight of a tri-sensitive crosslinking agent such as triacryl formal or trimethylol trimethacrylate may be used.

  The low boiling point hydrocarbon encapsulated in the outer shell of the thermally expandable functional resin fine particles is not particularly limited as long as the boiling point is equal to or lower than the softening temperature of the thermoplastic polymer, for example, propane, propylene, Low-boiling hydrocarbons such as butane, isobutane, pentane, isopentane, hexane, heptane, low-boiling organic halogen compounds such as fluorotrichloromethane, difluorochlorobromomethane, and tetrafluorodibromoethane, and low-boiling carbonization. Hydrogen and a low-boiling organic halogen compound can be used in combination, but particularly preferred is isobutane, butane, or hexane because the coefficient of thermal expansion can be increased and production is easy. And content of the volatile liquid with respect to a low boiling point hydrocarbon is 3 to 50%, and in order to obtain a high thermal expansion coefficient, 5 to 30% is especially preferable. Such thermally expandable functional resin fine particles are disclosed in, for example, Japanese Patent Publication No. 5-15499.

(Thermal expansion insulating layer)
The heat-expandable insulating layer can be formed by forming a heat-expandable insulating layer in advance and combining it with the resin-impregnated paper-like material by heat melting or using a heat-resistant adhesive. Alternatively, a coating material containing thermally expandable functional resin fine particles may be applied to the resin-impregnated paper-like material.

  The thickness of the heat-expandable insulating layer may be appropriately designed from the dimension after the thermal expansion of the electrical insulating paper of the present invention and the dimension of the space that requires the electrical insulation to be applied, and is not particularly limited. In addition, since at least one layer of the thermally expandable functional resin fine particles is included, it is sufficient that the functional resin fine particles have a thickness equal to or larger than the average particle diameter of the functional resin fine particles. It is. Although there is no upper limit for the thickness of the thermally expandable insulating layer, the paper and the electrical insulating paper are heated in consideration of the balance between the thickness after the thermally expandable insulating layer is thermally expanded and the thickness of the paper. What is necessary is just to design in the range which does not impair the electric insulation of the electric insulator which match | combined with the electric insulation space (it mentions later) obtained by doing.

  In order to improve heat resistance, a thermosetting resin can be appropriately added to the thermally expandable insulating layer. The shape of the thermosetting resin is not particularly limited as long as it does not hinder the formation of the thermally expandable insulating layer by coating or the like, and may be fine or fibrous, and the size is an appropriate design matter. Examples of the thermosetting resin include epoxy resin, novolac phenol resin, resol phenol resin, phenol resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, polyurethane, thermosetting polyimide, and the like. .

  When the heat-expandable insulating layer in the electrically insulating paper of the present invention is formed on the resin-impregnated paper-like material by coating, the heat-expandable functional resin fine particles can be emulsified and applied. The additive used when providing a coating layer is not specifically limited, Auxiliaries, such as a binder, a dispersing agent, a water retention agent, and an antifoamer, can be used suitably.

  As a method of providing a coating layer of thermally expandable functional resin fine particles, known methods such as blade coater, air knife coater, roll coater, comma coater, brush coater, kiss coater, curtain coater, bar coater, gravure coater, die coater, etc. It can select suitably from the methods using a coating machine.

  As a drying method after coating, as long as it is necessary to carry out at a drying temperature lower than the boiling point of the low boiling hydrocarbon encapsulated in the outer shell of the thermally expandable functional resin fine particles, a known method is used. For example, a normal method such as a steam heater, a gas heater, an infrared heater, an electric heater, a hot air heater, a microwave, a cylinder dryer, etc. can be employed, and after drying, if necessary, Smoothness can be imparted by finishing processes such as super calendering and soft calendering that are post-processing, and any other common paper processing method can be applied. It is necessary to process at a temperature lower than the boiling point of the hydrocarbon.

(Other ingredients)
In the present invention, the paper-like material, the impregnating resin, and the thermally expandable insulating layer may contain various additives as long as the effects of the present invention are not impaired. The type of this additive is not particularly limited, and is a tackifier resin, a flame retardant, an antioxidant, an inorganic filler, a cell nucleating agent, a crystal nucleating agent, a heat stabilizer, a light stabilizer, an ultraviolet absorber, a plasticizer, a lubricant, Common plastic compounding agents such as pigments, cross-linking agents, cross-linking aids, and silane coupling agents can be mentioned. The mixing ratio of these additives is an appropriate design matter.

<Electric insulating space obtained by heating electric insulating paper>
An electrically insulating space obtained by heating the electrically insulating paper of the present invention will be described with reference to FIG. FIG. 2A shows the positional relationship of a part of the members of the electric motor or transformer, in which the core material 4 made of an iron core or the like and the coil 5 are arranged via a narrow space 10 that requires electrical insulation. Yes. FIG. 2B shows a state in which the electrical insulating paper 11 of the present invention is inserted into the narrow space 10 that requires electrical insulation shown in FIG. The electrical insulating paper 11 is illustrated as having a thermally expandable insulating layer 2 disposed on both sides of the paper-like material 1 shown in FIG. FIG. 2C shows a state in which an electrically insulating space 3 obtained by heating the electrically insulating paper by heating the whole of FIG. 2B is formed. The state in which the paper 1 and the electrically insulating space 3 obtained by heating the electrically insulating paper are combined is the electrical insulator of the present invention.

  Since the electrical insulating paper increases in thickness by heating and has a gap filling function in a narrow space, an electrical insulating space 3 in which a narrow space 10 requiring electrical insulation is filled with an insulating member can be formed, and electrical insulation can be performed. It is possible to increase the adhesion with a necessary conductive member (for example, the core material 4 and the coil 5). Further, a plurality of conductive members (for example, the core material 4 and the coil 5) that need electrical insulation can be bonded and fixed in a state where the electrical insulation space 3 is formed without changing their three-dimensional positional relationship. . Since the electrical insulation space obtained by heating the electrical insulation paper of the present invention is excellent in electrical insulation and heat resistance and has oil resistance, it can be used as an interphase insulation application for electric motors and transformers.

  The relative dielectric constant of the electrically insulating space obtained by heating the electrical insulating paper of the present invention was measured by the complex dielectric constant at a frequency of 1 GHz by the cavity resonator contact method, and the real part was taken as the relative dielectric constant. The measuring instrument uses a strip-shaped sample (sample size 2 mm × 70 mm length) by a cylindrical cavity resonator (“Network Analyzer N5230C” manufactured by Agilent Technologies, “Cavity Resonator 1 GHz” manufactured by Kanto Electronics Application Development Co., Ltd.). Measured.

  The electrical insulating space obtained by heating the electrical insulating paper of the present invention preferably has a relative dielectric constant of 2.0 or less at 1 GHz. If the dielectric constant of the electrically insulating space is 2.0 or less, it becomes possible to make the dielectric constant at 1 GHz of the electrically insulating resin sheet for motors 2.0 or less, and when used as an insulating member of a motor. In addition, dielectric breakdown due to surge voltage can be prevented. On the other hand, if the relative dielectric constant at 1 GHz exceeds 2.0, it is difficult to make the relative dielectric constant 2.0 or less when an electrically insulating resin sheet for motors is configured. In the present invention, the relative dielectric constant at 1 GHz of the porous resin layer is preferably 1.9 or less, more preferably 1.8 or less (usually 1.4 or more). The relative dielectric constant depends on the specific dielectric constant specific to the electrically insulating space, but can be reduced by increasing the porosity.

  The relative dielectric constant of the electrically insulating space obtained by heating the electrical insulating paper of the present invention was measured by the complex dielectric constant at a frequency of 1 GHz by the cavity resonator contact method, and the real part was taken as the relative dielectric constant. The measuring instrument uses a strip-shaped sample (sample size 2 mm × 70 mm length) by a cylindrical cavity resonator (“Network Analyzer N5230C” manufactured by Agilent Technologies, “Cavity Resonator 1 GHz” manufactured by Kanto Electronics Application Development Co., Ltd.). Measured.

  The electrically insulating space obtained by heating the electrically insulating paper of the present invention preferably has a thickness of 10 μm or more, more preferably in the range of 20 to 500 μm. If the thickness is in the range of 10 μm or more, there is an advantage that the insulating property can be maintained in the electrically insulating resin sheet for motors. On the other hand, when the thickness of the porous resin sheet is less than 10 μm, dielectric breakdown is likely to occur, and when it exceeds 500 μm, there is a possibility that the electric energy conversion efficiency is lowered and the motor output is lowered.

  The average bubble diameter of the bubbles contained in the electrically insulating space obtained by heating the electrically insulating paper of the present invention is preferably 5.0 μm or less, more preferably 4.5 μm or less, particularly 4.0 μm. The following is preferable (usually 0.01 μm or more). If the average cell diameter of the porous resin layer is 5.0 μm or less, there is an advantage that the relative dielectric constant can be lowered without lowering the insulation and mechanical strength. Mechanical strength may decrease.

  The average bubble diameter of the bubbles contained in the electrically insulating space obtained by heating the electrically insulating paper of the present invention is determined by measuring the cut surface of the porous resin layer with a scanning electron microscope (SEM) (“S-3400N manufactured by Hitachi, Ltd.). ”), The image was binarized with image processing software (“ WinROOF ”manufactured by Mitani Corporation), separated into a bubble portion and a resin portion, and the maximum vertical chord length of the bubbles was measured. The average value of 50 bubbles from the larger bubble diameter was taken as the average bubble diameter.

  Further, the porosity of the electrically insulating space obtained by heating the electrically insulating paper of the present invention is preferably 30% or more, and more preferably 40% or more. If the porosity of the porous resin layer is 30% or more, there is an advantage that uniform pores exist in the porous resin layer, the variation in dielectric characteristics is reduced, and a low dielectric constant can be achieved. If it is less than 30%, the vacancy formation state is more uneven and the dielectric characteristics tend to vary, and the relative dielectric constant may not be lowered.

The porosity of the electrically insulating space obtained by heating the electrically insulating paper of the present invention is determined by measuring the specific gravity of the thermoplastic resin composition before porosity and the porous resin layer after porosity. Calculated.
Porosity (%) = [1− (specific gravity of porous resin layer / specific gravity of thermoplastic resin composition before porosity)] × 100

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

<Preparation of sample>
[Example 1]
As paper,
Heat-resistant insulation paper (trade name: TZA, manufactured by Shinyodogawa Paper Co., Ltd.)
Were each cut into a size of 30 cm × 20 cm.
It is an electrically insulating varnish as an impregnating resin,
Phenolic varnish (manufactured by Hitachi Chemical Co., Ltd., trade name: HPD-200)
Was used to prepare an impregnating resin solution with ethyl alcohol so that the solid content was 40%.
100 g of the impregnating resin solution was poured into a stainless steel vat, and the cut paper was put into the vat and allowed to stand for 1 minute to impregnate the resin.
The paper-like material was pulled out from the vat and dried by placing it in a hot air dryer set at a temperature of 120 ° C. for 5 minutes to produce a paper-like material having a resin impregnation amount of 20 g / cm ² .
continue,
Thermally expandable functional resin particles (Matsumoto Yushi Seiyaku Co., Ltd., trade name: F190D) 20 g
Is dissolved in 20 g of toluene, coated on the resin-impregnated paper using a Mayer bar, and dried with a warm air dryer set at a temperature of 120 ° C. to give a heat of 50 g / m ² . An insulative insulating layer was formed to obtain an electrical insulating paper of Example 1.

[Example 2]
An electrically insulating paper of Example 2 was obtained in the same manner as in Example 1 except that the paper-like material was changed to the following aramid paper.
Aramid paper (DuPont, product name: Nomex)

[Example 3]
An electrically insulating paper of Example 3 was obtained in the same manner as in Example 1 except that the paper-like material was changed to the following paper / film laminated paper.
Paper / film laminated paper (manufactured by Shinyodogawa Paper, trade name: semi-synthetic paper 200M)

[Reference Example 1]
The paper-like material of Example 1 was used as the electrical insulating paper of Reference Example 1. However, the electrical insulating paper of Reference Example 1 is a conventional method in which an electrical insulating material is formed by first placing an electrical insulating paper in a narrow space where electrical insulation is necessary, and then pouring varnish into the space and performing resin impregnation. This method is reproduced. Therefore, in the measurement of the rate of decrease in dielectric breakdown strength and the rate of decrease in fixed strength made of the electrical insulating paper of Reference Example 1, the electrical insulation paper is first installed in a narrow space where electrical insulation is required, and then the resin impregnation is performed. Therefore, an electrical insulator formed by the electrical insulating paper of Reference Example 1 was produced by another method described later.
Heat-resistant insulation paper (trade name: TZA, manufactured by Shinyodogawa Paper Co., Ltd.)

<Measurement and evaluation method>
As the heat resistance evaluation, the electrical insulators formed on the samples of Examples and Reference Examples were evaluated for the rate of decrease in dielectric breakdown strength and the rate of decrease in fixed strength before and after applying the thermal history.
The fixing strength referred to in the present invention is the effect of the electrical insulating paper of the present invention in which a plurality of conductive members are bonded and fixed in a state where the electrical insulating space is formed without changing their three-dimensional positional relationship. It is an index to evaluate. In the following Examples and Reference Examples, evaluation was performed by replacing the fixing strength with the peel strength between the iron plate and the copper foil.

(Decrease rate of dielectric breakdown strength)
-Preparation of test piece The test piece of the electrical insulating paper of Examples 1 to 3 was placed horizontally on an iron plate piece having a width of 50 mm, a length of 100 mm, and a thickness of 1 mm, and a width of 2 mm on each of the two long sides of the iron piece. X PTFE spacer with a length of 100 mm x thickness of 500 μm, a copper plate piece with the same dimensions as the iron plate piece on the upper side, and a 40 mm width x 100 mm length gap formed by the spacer In the state where the electrical insulating paper was installed, it was heated in a warm air dryer at a temperature of 180 ° C. for 1 minute, and then naturally cooled at room temperature to prepare a test piece of the electrical insulating paper of the example. At this time, it was visually confirmed that the test piece of the example was thermally expanded and the gap between the iron plate piece and the copper plate piece was filled.

  A test piece of electrical insulating paper of Reference Example 1 was also produced according to the test piece of the above example. An iron plate piece of width 50 mm × length 100 mm × thickness 1 mm is horizontally placed, and a PTFE spacer of width 2 mm × length 100 mm × thickness 500 μm is installed on each of the two long sides of the iron plate piece. The phenolic varnish (manufactured by Hitachi Chemical Co., Ltd.) was installed with an electrical insulating paper of an embodiment having a width of 40 mm and a length of 100 mm installed in a gap formed by a spacer. , Trade name: HPD-200), the two short sides of the iron plate pieces are sealed with PTFE tape so that the varnish component does not leak, and heated at 180 ° C. for 30 minutes in a warm air dryer, then at room temperature. The sample was then naturally cooled to prepare a test piece of the electrical insulating paper of the example. At this time, it was visually confirmed that the test piece of the example was thermally expanded and the gap between the iron plate piece and the copper plate piece was filled.

-Preparation of test piece after heat history application (exposure) The test piece for evaluation was exposed in a hot air dryer at a temperature of 200 ° C for 1000 hours, and then naturally cooled at room temperature to prepare a test piece after exposure. .
The test piece on which the electrical insulator is formed is exposed to a temperature of 200 ° C. for 1000 hours using a hot air dryer, and the dielectric breakdown strength (unit: kV / mm) of the electrical insulator before and after the exposure is set to JIS C2300-2. According to the measurement, the reduction rate was calculated by the following formula.

(Reduction rate of dielectric breakdown strength) [%]
= (Dielectric strength before exposure-Dielectric strength after exposure) / (Dielectric strength before exposure) x 100

  The rate of decrease in dielectric breakdown strength [%] is closer to 0% and the decrease in dielectric breakdown strength due to exposure is small and can be said to be excellent. However, when the exposure under the above conditions is approximately 50% or less, it is formed from conventional electrical insulating paper. It can be said that there is performance equivalent to an electrical insulator.

(Decrease rate of fixed strength)
The evaluation of the fixing strength is based on the fact that an electrical insulator made of electrical insulating paper is intimately sandwiched between an iron plate and a copper foil that maintain a certain inter-surface distance via a spacer. A test piece having a gripping margin and having an iron plate and a copper foil bonded and fixed by the electrical insulator was used. Further details are described below.

-Preparation of test piece The test piece of the electrical insulating paper of Examples 1 to 3 is a square with a side of 20 cm and a steel plate with a thickness of 2 mm, and a square with a side of 20 cm and a thickness of 500 μm on the upper surface and a center part. A PTFE spacer having a through window with a width of 25 mm and a length of 150 mm is installed, and the electrical insulating paper of the embodiment with a width of 25 mm and a length of 150 mm is inserted into the through window, and the upper side is 35 mm wide × 200 mm long × thick. A 38 μm thick copper foil is placed in parallel with the iron plate so that the electrical insulating paper is completely hidden and the gripping margin of about 30 mm remains, and is heated at a temperature of 180 ° C. for 1 minute in a hot air dryer and then naturally at room temperature. It cooled and produced the test piece of the electrical insulation paper of the Example. At this time, it was visually confirmed that the test piece of the example was thermally expanded and the gap between the iron plate and the copper foil was filled.

  A test piece of electrical insulating paper of Reference Example 1 was also produced according to the test piece of the above example. A steel plate with a side of 20 cm square and a thickness of 2 mm is placed horizontally, and a PTFE spacer with a square with a side of 20 cm and a thickness of 500 μm and a through-hole with a width of 25 mm and a length of 150 mm at the center is installed on its upper surface, An electrical insulating paper of a reference example having a width of 25 mm × a length of 150 mm was placed inside the through window and then filled with the phenolic varnish (manufactured by Hitachi Chemical Co., Ltd., trade name: HPD-200). Heated at 180 ° C for 30 minutes in a hot air dryer with a copper foil of length 200mm x thickness 38μm placed in parallel with the iron plate so that the electrical insulating paper is completely hidden and the gripping margin of about 30mm remains. Then, the sample was naturally cooled at room temperature to prepare a test piece of the electrical insulating paper of the reference example. At this time, it was visually confirmed that the test piece of the reference example was filled with a gap between the iron plate and the copper foil with varnish.

-Preparation of test piece after heat history application (exposure) The test piece for evaluation was exposed in a hot air dryer at a temperature of 200 ° C for 1000 hours, and then naturally cooled at room temperature to prepare a test piece after exposure. .

・ Measurement / Evaluation of Fixed Strength Prepare 5 specimens before and after exposure in Examples 1 to 3 and Reference Example 1, respectively, and use a universal tensile tester to install an iron plate horizontally. The 90 ° peel strength (unit: N) was measured according to JIS K6854-1, with the gripping area held between the chucks, and the average value of the five values was taken as the measured value. As described above, the decrease rate of the peel strength after the exposure before the exposure was regarded as the decrease rate of the fixed strength, and was calculated by the following formula.

(Decrease rate of fixed strength) [%]
= (Decrease rate of peel strength) [%]
= (Peeling strength before exposure-Peeling strength after exposure) / (Peeling strength before exposure) x 100

  The rate of decrease in fixed strength [%] value is closer to 0% and the decrease in dielectric breakdown strength due to exposure is small and excellent. However, if the exposure under the above conditions is approximately 50% or less, the electricity formed from conventional electrical insulating paper is used. It can be said that it has the performance of an insulator.

  Table 1 shows the configuration of the test pieces using the electrical insulating paper of Examples and Reference Examples, and Table 2 shows the evaluation results.

From the results shown in Table 2, the electrical insulator formed from the electrical insulating paper of the present invention shown in Examples 1 to 3, and the electrical insulator formed from the conventional electrical insulating paper shown in Reference Example 1, It can be seen that the breakdown voltage reduction rate and the fixed strength reduction rate are substantially equal. That is, the electrical insulating paper of the present invention has the same characteristics as the conventional electrical insulating paper in terms of dielectric breakdown voltage and fixed strength.
In addition, the electrical insulating paper of the present invention does not require a varnish pouring step, which is necessary for conventional electrical insulating paper, in the method for forming an electrical insulator in a narrow space where electrical insulation is required, and further heating. It can be completed in as little as 1 minute. That is, the electrical insulating paper of the present invention is superior to conventional electrical insulating paper in forming an electrical insulator in a narrow space where electrical insulation is required.
As described above, the electrical insulating paper of the present invention can form an electrical insulating space in which a narrow space requiring electrical insulation is filled with an insulating member, and at the same time, enhances the adhesion to a conductive member requiring electrical insulation. It is possible. Furthermore, a plurality of conductive members that require electrical insulation can be bonded and fixed in a state where the electrical insulation space is formed without changing their three-dimensional positional relationship.

DESCRIPTION OF SYMBOLS 1 Paper-like material 2 Thermally expansible insulating layer 3 Electrical insulating space obtained by heating a thermally expansible insulating layer 4 Core material 5 Coil 10 Narrow space where electric insulation is required 11 Electrical insulating paper

Claims (4)

  An electrically insulating paper comprising a thermally expandable insulating layer containing thermally expandable functional resin fine particles disposed on one side or both sides of a paper-like material.   The functional resin fine particles are composed of an outer shell made of a thermoplastic polymer having an average particle diameter of 5 to 50 μm and a film thickness of 2 to 15 μm, and a low boiling hydrocarbon encapsulated in the outer shell. The electrically insulating paper according to claim 1, wherein the electrically insulating paper is a thermally expandable microcapsule having a boiling point not higher than a softening temperature of the thermoplastic polymer.   An electrical insulator obtained by heating after laminating the electrical insulating paper according to claim 1 on a member.   An electric motor and a transformer having an electrically insulating space obtained by heating the electrically insulating paper according to claim 1.

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