Insulating material composition

Abstract

The present invention relates to an insulating material composition having a high glass transition temperature and a low shrinkage rate by comprising cerium oxide. When used as an insulating material in a rotating electrical device, insulation properties, reliability, and service life may be improved.

Description

Insulating composition

[0001] The present invention relates to an insulating composition.

[0002]

[0003] A rotating electrical device such as a motor or a generator includes a rotor and a stator, and the stator has an annular stator core having a plurality of slots in the circumferential direction of the inner surface. A coil is wound around the slots, and an insulating layer is formed between the slots and the coils in the stator to ensure electrical insulation.

[0004] Conventionally, a method has been used to form an insulating layer by inserting insulating paper between slots and coils in a stator. In order to insert insulating paper into a rotating electric machine according to the above method, a process of unwinding and supplying the insulating paper, cutting it, bending it to have a predetermined shape, and then inserting it into a slot or the like in the rotating electric machine is required. Various technologies have been proposed in relation to the insulating paper and a device for manufacturing the same. For example, Korean Patent Publication No. 10-1999-0015205 discloses an insulating paper for a motor in which both wings and a fixing member for fixing the wings are formed as one piece, and a device for manufacturing the same.

[0005] However, since a single manufacturing device can only manufacture a single shape of insulating paper, separate insulating paper manufacturing devices must be used for each shape to manufacture insulating paper of various shapes used in various types of rotating electrical machines, resulting in significant inefficiencies in terms of cost and time. Furthermore, conventional insulating paper has low strength and thermal conductivity, making it difficult to sufficiently suppress temperature rise in rotating electrical machines.

[0006] To address these issues, a technology has been proposed that uses a thermosetting resin composition containing a large amount of inorganic filler as the insulating material instead of insulating paper. However, existing insulating materials using thermosetting resin compositions suffer from the problem of not being able to exhibit sufficient electrical insulation properties.

[0007] Meanwhile, a technology for molding an insulation portion inside a stator slot using, for example, an epoxy molding compound (EMC), a thermosetting resin composition, has been proposed. Due to the nature of EMC materials that are melted and molded at high temperatures (over 120°C), the molten EMC composition is injected into the slot using a transfer molding method, a compression molding method, or an injection molding method to form an insulation layer with a thickness of 100 to 400 μm, thereby forming an insulation layer inside the motor. However, depending on whether the motor is running, it is heated or cooled, and the insulation layer inside the motor undergoes repeated thermal expansion and contraction. As a result, the fatigue of the insulation layer increases, which reduces its durability, and may cause the insulation layer to be destroyed or to peel off from the inside of the stator slot, resulting in a problem of deterioration of the insulation properties inside the motor. Therefore, an insulation material with a high glass transition temperature and low shrinkage rate is required.

[0008]

[0009] The present invention provides an insulating composition having a high glass transition temperature and low shrinkage.

[0010]

[0011] The present invention comprises an epoxy resin, a hardener, a filler and cerium oxide, and the particle size (D) of the cerium oxide 50 ) is 0.1 to 1.0 ㎛ and the specific surface area is 50 to 130 m2 / g.

[0012]

[0013] The present invention provides an insulating composition having a high glass transition temperature and low shrinkage. The insulating composition according to the present invention can be filled between slots and coils in a rotating electric machine, filling the gap between the slots and coils and replacing insulating paper to impart insulating properties. The insulating composition of the present invention exhibits superior insulating properties compared to conventional insulating compositions containing thermosetting resins, and therefore can be applied to rotating electric machines requiring superior insulating properties, such as motors for electric vehicles, for use in impregnating rotor coils.

[0014]

[0015] The present invention will be described in detail below. However, it is not limited to the following description, and each component may be modified or selectively mixed as needed. Therefore, it should be understood that all modifications, equivalents, and alternatives included within the spirit and technical scope of the present invention are included.

[0016] “Viscosity” as used herein is measured by a conventional method known in the art, and can be measured, for example, using an ICI viscometer at 150°C. “Particle size (D 50 )” is measured by a conventional method known in the art, and can be measured, for example, by laser light scattering (LLS). “Softening point” is measured by a conventional method known in the art, and can be measured, for example, by a dropping point system calorimetry DP70 from Mettler Toledo. “Glass transition temperature” is measured by a conventional method known in the art, and can be measured, for example, by thermomechanical analysis (TMA) or differential scanning calorimetry (DSC).

[0017]

[0018] <Insulating material composition>

[0019] The insulating composition of the present invention comprises an epoxy resin, a curing agent, a filler, and cerium oxide. The present invention relates to a particle size (D 50 ) is 0.1 to 1.0 ㎛ and a specific surface area of ​​50 to 130 m2 / g, thereby providing an insulating composition having excellent electrical insulating properties, a high glass transition temperature, and a low shrinkage rate. The insulating composition may further include additives commonly used in the relevant technical field, such as an adhesion enhancer, a colorant, a catalyst, and a flame retardant, as needed.

[0020]

[0021] epoxy resin

[0022] In the present invention, epoxy resin is used as a main resin, and by reacting with a curing agent and curing, a three-dimensional network structure is formed, thereby imparting strong and solid adhesion properties and heat resistance to an adherend.

[0023] As the epoxy resin, an epoxy resin commonly used in the relevant technical field can be used, and for example, one containing two or more epoxy groups in its molecular structure can be used. Non-limiting examples of epoxy resins that can be used include bisphenol A type epoxy resin, alicyclic epoxy resin, cresol novolac type epoxy resin, dicyclopentadiene type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, anthracene type epoxy resin, non-condensed ring type polycyclic structure epoxy resin, bisphenol fluorene modified epoxy, etc., and one or more of these can be included. For example, the epoxy resin may include a mixture of formaldehyde, polymer with 1,1'-biphenyl and phenol, glycidyl ether, 2,2'-{{1-4-[1-methyl-1-[4-(2-oxiranylmethoxy)phenyl]phenyl]ethylidene]bis, or a mixture thereof.

[0024] The epoxy resin may be one having an epoxy equivalent of 100 to 400 g / eq, for example, 200 to 300 g / eq, a softening point of 30 to 100°C, for example, 50 to 70°C, and a viscosity (150°C) of 0.01 to 0.2 Pa·s, for example, 0.05 to 0.15 Pa·s. If the epoxy equivalent is less than the above-mentioned range, the cured density may increase, resulting in poor moisture resistance reliability, and if it exceeds the above-mentioned range, the curability may be poor. If the softening point is less than the above-mentioned range, mixing may not occur well, resulting in insufficient dispersion between materials, and if it exceeds the above-mentioned range, the fluidity may be affected, resulting in the generation of pores during molding. If the viscosity is below the aforementioned range, excessive bleed / flash (B / F) may occur during molding due to low viscosity, and if it exceeds the aforementioned range, the high viscosity may reduce flowability and cause an underfill phenomenon during molding.

[0025] Based on the total weight of the insulating material composition, the content of the epoxy resin may be 0.1 to 30 wt%, for example, 1 to 20 wt%. If the content of the epoxy resin is less than the above-mentioned range, adhesion, flowability, and moldability may be reduced, and if it exceeds the above-mentioned range, the content of the filler may be reduced, resulting in a reduction in mechanical strength.

[0026]

[0027] hardener

[0028] The insulating composition according to the present invention includes a curing agent. The curing agent reacts with the epoxy resin, and through curing, forms a seal between the stator slot and the coil, thereby imparting insulating properties to the stator.

[0029] As the above curing agent, a curing agent known in the art that undergoes a curing reaction with an epoxy resin can be used. For example, the curing agent can be a phenolic compound having two or more phenolic hydroxyl groups in one molecule. For example, the curing agent can include at least one selected from the group consisting of an acid anhydride compound, a phenol novolac resin, a cresol novolac resin, a phenol aralkyl resin, and a polyfunctional phenol compound. For example, the curing agent can include a phenolic resin, for example, a 1,3-benzenediol polymer with 4,4-bis(chloromethyl)-1,1-biphenyl and phenol. In this case, the adhesion can be further improved.

[0030] The above curing agent may be one having a hydroxyl equivalent of 100 to 180 g / eq, for example, 125 to 145 g / eq, a softening point of 70 to 120°C, for example, 90 to 100°C, and a viscosity (150°C) of 0.3 to 1.0 Pa·s, for example, 0.5 to 0.8 Pa·s. If the hydroxyl equivalent is less than the above-mentioned range, the adhesiveness of the insulating composition may be reduced, and if it exceeds the above-mentioned range, the glass transition temperature of the insulating composition may be lowered and the mechanical properties may be reduced. If the softening point and viscosity are less than the above-mentioned range, excessive bleed flash may be caused during molding, and if it exceeds the above-mentioned range, it may affect the fluidity, causing incomplete molding, such as underfilling, during molding.

[0031] Based on the total weight of the insulating material composition, the content of the curing agent may be 0.1 to 15 wt%, for example, 1 to 10 wt%. If the content of the curing agent is less than the above-mentioned range, curability and formability may be reduced, and if it exceeds the above-mentioned range, reliability and strength may be reduced due to increased moisture absorption.

[0032]

[0033] The insulating composition according to the present invention uses an epoxy resin having an epoxy equivalent of 100 to 400 g / eq, a softening point of 30 to 100°C, and a viscosity (150°C) of 0.01 to 0.2 Pa·s, and a curing agent having a hydroxyl equivalent of 100 to 180 g / eq, a softening point of 70 to 120°C, and a viscosity (150°C) of 0.3 to 1.0 Pa·s, and allows them to undergo a curing reaction with each other, thereby securing a glass transition temperature (Tg) of 150°C or higher. When the above insulating composition is used as an insulating material between a slot and a coil in a rotating electric machine, it is possible to prevent cracks caused by shrinkage / expansion due to temperature changes even when exposed to a high temperature environment (100°C or higher) for a short period of time when the motor is running, exposed to room temperature during a cooling process or when the motor is not running, and exposed to a temperature below room temperature (25°C) depending on the season or surrounding environment, thereby providing an insulating material with excellent durability.

[0034]

[0035] filler

[0036] The insulating composition according to the present invention includes a filler. The filler imparts strength to the insulating composition, controls flowability, thereby enhancing formability and durability.

[0037] The above filler may be formed of any one or a combination of at least two selected from non-metal oxides, metal nitrides, non-metal nitrides, inorganic hydrates, or inorganic salts, and may be used in combination, for example, with silica, silica nitride, alumina, alumina nitride, boron nitride, etc. For example, the filler may be silica.

[0038] For example, the average particle diameter (D) of the above filler 50 ) can be used having a size of 10 to 30 μm, for example, 12 to 18 μm.

[0039] Based on the total weight of the insulating composition, the content of the filler may be 50 to 90 wt%, for example, more than 80 wt% and less than or equal to 90 wt%. If the content of the filler is less than the above-mentioned range, the mechanical strength of the cured product of the insulating composition may be lowered and the moisture absorption may be increased, which may lower the reliability, and the amount of leakage current may increase due to the deterioration of the electrical properties, and if it exceeds the above-mentioned range, the fluidity may be lowered, which may result in poor formability.

[0040]

[0041] cerium oxide

[0042] The insulating composition according to the present invention includes cerium oxide. Cerium oxide is a material with high heat stability, which acts as a heat stabilizer by increasing the volume resistivity of epoxy resin, and also, by oxidation and reduction of cerium, it can combine with halogen elements, thereby forming ions (F - , Cl - ) plays a role in reducing mobility. Therefore, when cerium oxide is included, the electrical resistance value at high temperatures is improved, providing excellent insulating properties, and reducing leakage current by hindering the movement of ions within the insulating composition.

[0043] The present invention relates to a particle size (D 50) is 0.1 to 1.0 ㎛ and a specific surface area of ​​50 to 130 m2 / g, thereby providing an insulating composition having excellent electrical insulating properties, a high glass transition temperature, and a low shrinkage rate. The insulating composition of the present invention can be applied as an insulating composition for a rotating electric machine, for example, an insulating composition for impregnating a rotor coil.

[0044] The particle size (D) of the above cerium oxide 50 ) may be 0.1 to 1.0 ㎛, for example, 0.1 to 0.7 ㎛. If the particle size is less than the above-mentioned range, the particles may not be evenly distributed due to agglomeration, which may result in deterioration of properties. If the particle size exceeds the above-mentioned range, the dispersibility may be poor, which may result in deterioration of properties.

[0045] The specific surface area of ​​the above cerium oxide may be 50 to 130 m2 / g, for example, 70 to 120 m2 / g. If the specific surface area is less than the above-mentioned range, the dispersibility within the resin may be poor, resulting in deterioration of properties. If the specific surface area exceeds the above-mentioned range, the dispersibility may be reduced due to agglomeration between particles caused by the high specific surface area.

[0046] Based on the total weight of the insulating composition, the content of the cerium oxide may be 0.01 to 5 wt%, for example, 0.1 to 1 wt%. If the content of the cerium oxide is less than the above-mentioned range, the thermal stability and ion mobility reduction effects may be insufficient, and if it exceeds the above-mentioned range, the moisture absorption rate may rapidly increase, thereby reducing the insulating effect.

[0047]

[0048] additives

[0049] The insulating composition according to the present invention may further include additives commonly used in the relevant technical field, such as an adhesion enhancer, a colorant, a catalyst, a flame retardant, etc., as needed.

[0050] The adhesion enhancer is used to improve the bonding between organic and inorganic substances and the adhesion to metal substrates, and may include epoxy silane, amino silane, mercapto silane, acrylic silane, vinyl silane, etc. In addition, additives such as a coloring agent (e.g., carbon black, Bengala, etc.) for imparting color to the resin composition, a catalyst (e.g., phosphorus catalyst, imidazole catalyst, etc.) for improving the curing speed and workability, and a flame retardant (e.g., phosphorus flame retardant, metal hydroxide, etc.) may be further included.

[0051] The above additives may be added within a content range that does not impair the physical properties of the insulating composition of the present invention, and for example, may be included in an amount of 0.01 to 10 wt%, respectively, based on the total weight of the insulating composition, but is not limited thereto.

[0052]

[0053] The present invention relates to a particle size (D 50 ) is 0.1 to 1.0 ㎛ and a specific surface area of ​​50 to 130 m2 / g, thereby providing an insulating composition having a high glass transition temperature and a low shrinkage rate. When the insulating composition is used to form an insulating part inside a stator slot of a rotating electric machine, for example, a motor, even if the motor is heated or cooled and expands and contracts repeatedly depending on whether the motor is driven, the insulating layer can be prevented from being destroyed or peeled off from the stator. Therefore, excellent insulating properties can be maintained when the rotating electric machine is driven, and not only the driving efficiency of the rotating electric machine but also its durability can be improved, thereby improving the service life.

[0054] The insulating composition according to the present invention may have a glass transition temperature of 150°C or higher, for example, 160 to 180°C, and a shrinkage rate of 0.3% or lower, for example, 0.01 to 0.3%. If the glass transition temperature is lower than the operating temperature, the temperature may be lower than the operating temperature, which may cause cracks in the insulating material when shrinking and expanding due to temperature rise and cooling processes. If the temperature exceeds the above-mentioned range, the moisture absorption rate may be relatively large, which may affect the insulating properties. If the shrinkage rate exceeds the above-mentioned range, peeling may occur between the insulating material and the slots when shrinking and expanding depending on the operating temperature, which may affect the insulating properties, etc.

[0055] The insulating composition according to the present invention may have a leakage current value of 50 mA or less, for example, 0 to 50 mA. If the leakage current value exceeds the above-mentioned range, the insulating function may be lost, and current may be applied to the stator, which may cause functional problems.

[0056] The above leakage current value can be measured by a measurement method including the steps of molding an insulating composition into a slot shaped like a stator slot and post-molding cure (at 175°C for 4 hours or more), inserting a copper coil (about 2 mm thick) wound in a square shape into the slot molded with the insulating composition, and then impregnating it with varnish (polyester resin, polyether resin, polyamide resin, polyimide resin, etc.) to prepare a specimen, bolting the specimen to a vibration test facility, and then applying vibration at 10 G and 60 Hz for 1 hour, leaving it at 150°C for 96 hours, connecting an electrode to the copper coil, and applying 2.2 kV AC for 1 minute, and measuring the leakage current value.

[0057]

[0058] <Rotating electrical machine>

[0059] The present invention provides a rotating electric machine (e.g., a motor) equipped with an insulating material formed from the aforementioned insulating material composition. The rotating electric machine may be a component for a vehicle. For example, the present invention provides a rotating electric machine including a rotor and a stator, wherein the stator has an annular stator core having a plurality of slots in a circumferential direction of an inner surface, a coil is wound around the slots, and an insulating material according to the present invention is provided between the slots and the coils.

[0060] The insulating material according to the present invention exhibits excellent insulating properties, and thus can be applied as an insulating material to provide insulating properties to rotating electric machines, such as electric vehicle motors, where high torque is required and thus the rotational speed and current applied to the stator increase. A rotating electric machine using the insulating material composition of the present invention as an insulating material can have reduced losses occurring during the energy conversion process, thereby improving driving efficiency and durability, and thus extending the service life.

[0061]

[0062] Hereinafter, the present invention will be described in more detail through examples. However, the following examples are intended only to aid understanding of the present invention and are not intended to limit the scope of the present invention in any way.

[0063]

[0064] [Experimental Example 1-13]

[0065] Each component was mixed according to the composition described in Tables 1 and 2 below to prepare an insulating material composition for each experimental example.

[0066]

[0067]

[0068]

[0069]

[0070] Epoxy 1: Formaldehyde, polymer with 1,1'-biphenyl and phenol, glycidyl ether (Cas. No: 1201169-35-8, EEW 270-284 g / eq, softening point 60-63 ℃, viscosity (150 ℃) 0.05-0.11 Pa·s)

[0071] Epoxy 2: Mixture of 2,2'-{{1-4-[1-methyl-1-[4-(2-oxiranylmethoxy)phenyl]phenyl]ethylidene]bis (Cas. No: 2015-3-6229, EEW 201-218 g / eq, softening point 56-65 ℃, viscosity (150 ℃) 0.07-0.17 Pa·s)

[0072] Epoxy 3: Formaldehyde polymer with (chloromethyl)oxirane and 2-Methylphenol (Cas. No: 29690-82-2, EEW 200-212 g / eq, softening point 67-70 ℃, viscosity (150 ℃) 0.4-0.5 Pa·s)

[0073] Curing agent 1: 1,3-Benzenediol polymer with 4,4-bis(chloromethyl)-1,1-biphenyl and phenol (Cas. No: 0918825-38-4, hydroxyl equivalent 130-140 g / eq, softening point 90-96 ℃, viscosity (150 ℃) 0.5-0.8 Pa·s)

[0074] Curing agent 2: Phenol polymer with 4,4-bis(methoxymethyl)1,1-bisphenyl (Cas. No: 0205830-20-2, hydroxyl equivalent 200-220 g / eq, softening point 65-75 ℃, viscosity (150 ℃) 0.09-0.12 Pa·s)

[0075] Filler: Silica (D 50 15 ㎛)

[0076] cerium oxide 1:D 500.5 ㎛, specific surface area 110 ㎡ / g

[0077] cerium oxide 2: D 50 0.3 ㎛, specific surface area 130 ㎡ / g

[0078] cerium oxide 3: D 50 1.0 ㎛, specific surface area 60 ㎡ / g

[0079] cerium oxide 4: D 50 0.1 ㎛, specific surface area 150 ㎡ / g

[0080] cerium oxide 5: D 50 2.0 ㎛, specific surface area 16 ㎡ / g

[0081] Titanium oxide: D 50 0.5 ㎛, specific surface area 80 ㎡ / g

[0082] Silane: Trimethoxy[3-(phenylamino)propyl]silane

[0083] Colorant: Carbon black

[0084] Flame retardant: Magnesium hydroxide

[0085] Catalyst: 2,4-diamino-6[2'-methylimidazolyl-(1')] ethyl-S-triazine isocyanuric acid addition compound (Cas. No: 68490-66-4)

[0086]

[0087] [Physical property evaluation]

[0088] The properties of the insulating material composition of each experimental example were measured using the following method, and the results are shown in Tables 3 and 4 below.

[0089]

[0090] Sample manufacturing

[0091] The insulating material composition manufactured in each experimental example was molded at 175°C for 120 seconds using a transfer molding method to produce a specimen for evaluating physical properties.

[0092]

[0093] glass transition temperature

[0094] Each specimen was used to measure the temperature from room temperature to 300°C at a heating rate of 10°C / min using a Thermo-mechanical Analyzer (TMA), and the glass transition temperature was obtained using the onset point technique. In general, considering the heat generated under the operating conditions of the stator, it is desirable to secure a glass transition temperature of 150°C or higher. For example, when it is 160°C or higher, cracks caused by shrinkage / expansion due to temperature rise and cooling processes can be prevented.

[0095]

[0096] Shrinkage rate

[0097] The maximum length in the longitudinal direction of each specimen was measured, and the length after post-molding cure (175 ℃, 4 hours) was measured, and the shrinkage rate was calculated through the ratio of the front and rear lengths.

[0098]

[0099] Spiral flow

[0100] The flowability of the insulating compositions of each experimental example was measured using an evaluation mold (EMMI-1-66) with a transfer molding press (175°C, 70 kgf / cm2). Since the insulating composition requires sufficient fluidity to completely fill the slot area, it is desirable to secure a flowability of 25 inches or more.

[0101]

[0102] Gel Time

[0103] The time from the melting point of the insulating composition manufactured in the experimental example to the gelation point was measured on a 175°C hot plate. Since sufficient time is required for the insulating composition to fill the stator, it is desirable to secure a gel time of 26 seconds or more.

[0104]

[0105] Flexural strength, flexural modulus

[0106] According to ASTM D790, the flexural strength of each specimen was evaluated by measuring the force (maximum load) at the breaking point during a UTM (Universal test machine) 3-point bending test. The flexural modulus was evaluated by measuring the slope of the graph of the maximum load (stress (kgf)) and maximum displacement (strain (mm)) occurring during the 3-point bending test.

[0107]

[0108] Vibration evaluation

[0109] The insulating composition of each experimental example was molded into a slot shaped like a stator slot, and post-molding cured (post-molding cure, 175°C for 4 hours or more), and a copper coil and an insulating sheet were placed into the slot molded with the insulating composition, and then impregnated with varnish to manufacture a specimen. After the specimen was bolted to a vibration test facility, vibration was applied at 10 G, 60 Hz for 1 hour, and then the presence or absence of damage to the molded insulating material was checked. If no cracks occurred, it was judged as pass, and if cracks occurred, it was judged as fail.

[0110]

[0111] Leakage current evaluation

[0112] After the vibration evaluation described above, each specimen was left at 150°C for 96 hours, and electrodes were connected to the copper coil and slot, and 2.2 kV AC was applied for 1 minute, and the leakage current value was measured. A leakage current value of 50 mA or less was judged as pass, and a value exceeding 50 mA was judged as fail.

[0113]

[0114]

[0115]

[0116]

[0117] As shown in Tables 3 and 4 above, the insulating material composition of Experimental Examples 1-9 according to the present invention exhibited excellent physical properties across all measured items. In particular, the insulating material composition of Experimental Examples 1-5, which used an epoxy resin (Epoxy 1, 2) having an epoxy equivalent of 100 to 400 g / eq, a softening point of 30 to 100°C, and a viscosity (150°C) of 0.01 to 0.2 Pa·s and a curing agent (Curing Agent 1) having a hydroxyl equivalent of 100 to 180 g / eq, a softening point of 70 to 120°C, and a viscosity (150°C) of 0.3 to 1.0 Pa·s, contained a high content of filler, and used cerium oxide in an amount of 1 wt% or less, exhibited even more excellent physical properties.

[0118] On the other hand, the insulating compositions of Experimental Example 10, which did not include cerium oxide, Experimental Example 11, which included titanium oxide instead of cerium oxide, and Experimental Examples 12 and 13, which used cerium oxide (cerium oxide 4, 5) outside the range of properties according to the present invention, exhibited generally inferior properties compared to Experimental Examples 1 to 9. In particular, the insulating compositions of Experimental Examples 10 to 13 exhibited inferior properties in at least one of the vibration evaluation and leakage current evaluation.

[0119]

[0120] The present invention provides an insulating composition having a high glass transition temperature and low shrinkage.

Claims

1. Contains epoxy resin, hardener, filler and cerium oxide, The particle size (D) of the above cerium oxide 50 ) is 0.1 to 1.0 ㎛ and the specific surface area is 50 to 130 ㎡ / g.

2. In the first paragraph, the epoxy resin has an epoxy equivalent of 100 to 400 g / eq, a softening point of 30 to 100°C, and a viscosity (150°C) of 0.01 to 0.2 Pa·s. An insulating composition in which the hydroxyl equivalent of the above-mentioned hardener is 100 to 180 g / eq, the softening point is 70 to 120°C, and the viscosity (150°C) is 0.3 to 1.0 Pa·s.

3. An insulating composition having a glass transition temperature of 150°C or higher and a shrinkage rate of 0.3% or lower in the first paragraph.

4. In the first paragraph, an insulating composition having a leakage current value of 50 mA or less measured by the following measurement method: <Measurement method> The insulating composition is molded into a slot shaped like a stator slot, post-molding cured (at 175°C for 4 hours or more), a copper coil is placed in the slot molded with the insulating composition, and then impregnated with varnish to manufacture a specimen, and the manufactured specimen is bolted to a vibration test facility, and vibration is applied at 10 G, 60 Hz for 1 hour, and left at 50°C for 96 hours, and then an electrode is connected to the copper coil, and 2.2 kV AC is applied for 1 minute to measure the leakage current value.

5. An insulating composition according to claim 1, comprising 0.1 to 30 wt% of the epoxy resin, 0.1 to 15 wt% of the hardener, 50 to 90 wt% of the filler, and 0.01 to 5 wt% of the cerium oxide, based on the total weight of the insulating composition.

6. An insulating composition used as an insulating material in a motor according to any one of claims 1 to 5.

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