Insulation material and rotary electric device including same

Abstract

The present invention provides an insulation material having excellent insulation and heat resistance. The insulation material according to the present invention may be filled between a slot and a coil in a rotary electric device to fill a gap between the slot and the coil and provide insulation properties by replacing an insulation paper. The insulation material of the present invention may be applied to a rotary electric device, such as a motor for an electric vehicle, in which a large torque is required to increase a rotation speed and a current applied to a stator.

Description

Insulating materials and rotating electrical machines containing the same

[0001] The present invention relates to an insulating material and a rotating electric machine including the same.

[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 only one type of insulating paper can be manufactured with a single manufacturing device, a separate insulating paper manufacturing device must be used for each shape to manufacture insulating paper of various shapes used in various types of rotating electrical equipment, resulting in significant inefficiency in terms of cost and time.

[0006]

[0007] The present invention provides an insulating material having excellent insulation properties and heat resistance. The present invention also provides a rotating electric machine equipped with the insulating material.

[0008]

[0009] The present invention provides an insulating material formed by curing an epoxy resin composition comprising an epoxy resin, a hardener, and a filler, which is provided between a slot and a coil in a stator of a motor, and which has a high temperature mass reduction rate of less than 2.0 wt% when 5 cycles are performed, with 24 hours of standing and exposure as one cycle in an oven at 275°C.

[0010]

[0011] The present invention provides an insulating material with excellent insulation and heat resistance. The insulating material 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 material of the present invention has excellent insulation and heat resistance, making it applicable 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.

[0012]

[0013] The present invention will be described in detail below. However, the scope of the present invention is not limited solely to the details described below, 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 encompassed.

[0014] As used herein, “viscosity” is measured by a conventional method known in the art, and can be measured, for example, using an ICI viscometer at 150°C. Functional values ​​such as “hydroxyl value” are measured by a conventional method known in the art, and can be measured, for example, by a titration method. “Particle size (D50)” is measured by a conventional method known in the art, and can be measured, for example, by laser light scattering (LLS).

[0015]

[0016] Insulating material

[0017] The insulating material of the present invention is provided between a slot and a coil in a stator of a motor, and is formed by curing an epoxy resin composition including an epoxy resin, a curing agent, and a filler, and when 5 cycles are performed, with 24 hours of standing and exposure in an oven at 275°C as one cycle, the high-temperature mass reduction rate is less than 2.0 wt%, for example, less than 1.5 wt%, or in another example, less than 1.0 wt%. The high-temperature mass reduction rate is calculated by the following equation.

[0018] High temperature mass loss rate (%) = [(W0- W 5cycle ) / W0] X 100

[0019] In the above equation, W0 is the mass of the cured insulation, and W 5cycle is the mass of the insulation after 5 cycles.

[0020] The insulating material of the present invention is formed by curing an epoxy resin composition, and serves to replace conventional insulating paper. The epoxy resin composition can be formed into a thin thickness (e.g., about 25 μm) between a slot and a coil in a stator of a motor. Therefore, when the resin component is decomposed due to high-temperature thermal decomposition, the thickness of the relevant portion becomes thin, and thus the insulation properties may deteriorate. The insulating material according to the present invention has excellent heat resistance with a high-temperature mass loss rate of less than 2.0 wt%, and can provide excellent insulation when applied to a rotating electric machine that is continuously exposed to a high-temperature environment.

[0021] An epoxy resin composition according to the present invention comprises an epoxy resin, a curing agent, and a filler.

[0022] For example, the epoxy resin may include a dicyclopentadiene-type epoxy resin, a phenol aralkyl-type epoxy resin, or a mixture thereof. In addition, the epoxy resin may further include various known epoxy resins within a range that does not impair the physical properties of the epoxy resin composition of the present invention.

[0023] Meanwhile, the epoxy resin composition may further include additives commonly used in the relevant technical field, such as an adhesion enhancer, a release agent, a curing accelerator, a colorant, a flame retardant, etc., as needed.

[0024]

[0025] Dicyclopentadiene type epoxy resin

[0026] The epoxy resin composition of the present invention may include a dicyclopentadiene-type epoxy resin as the epoxy resin. The dicyclopentadiene-type epoxy resin forms a three-dimensional network structure after reacting with a curing agent and curing, thereby imparting strong and solid adhesion properties to an adherend and heat resistance.

[0027] In the case of general thermosetting resins, there is a problem that thermal decomposition occurs at high temperatures of 200℃ or higher, resulting in a decrease in mass and, as a result, a rapid deterioration in the electrical insulation properties of the thermosetting resin. In the present invention, a dicyclopentadiene-type epoxy resin containing dicyclopentadiene having a large substituent in the molecular structure is used as the epoxy resin compared to the commonly used bisphenol-type and ortho-cresol novolac-type epoxy resins, thereby preventing the molecular structure from being decomposed even when exposed to harsh environments (high temperatures, etc.) due to such substituents.

[0028] Therefore, the epoxy resin composition of the present invention comprises a dicyclopentadiene-type epoxy resin including a bulky structure of dicyclopentadiene, thereby securing excellent heat resistance properties and preventing thermal decomposition at high temperatures and mass loss resulting therefrom, thereby preventing a decrease in electrical insulation properties.

[0029] The above dicyclopentadiene type epoxy resin may be represented by the following formula 1.

[0030] [Chemical Formula 1]

[0031]

[0032] In the above formula, n is an integer from 1 to 10.

[0033] When using a dicyclopentadiene type epoxy resin in which n exceeds 10, the viscosity of the epoxy resin composition increases, resulting in a decrease in dispersibility and moldability, and upon curing, the epoxy resin composition may become entangled with the hardener in a dense network structure, resulting in a decrease in brittleness and a decrease in durability.

[0034] The epoxy equivalent of the above dicyclopentadiene type epoxy resin may be 200 to 300 g / eq, for example, 250 to 280 g / eq. If the epoxy equivalent is less than the above-mentioned range, the high-temperature thermal decomposition characteristics may be deteriorated, and if it exceeds the above-mentioned range, the glass transition temperature (Tg) of the composition may be lowered and the mechanical properties may be deteriorated.

[0035] The viscosity (150°C) of the above dicyclopentadiene type epoxy resin may be 0.1 to 10 poise, for example, 0.1 to 4 poise. If the viscosity is less than the above-mentioned range, the high-temperature thermal decomposition characteristics may deteriorate, and if it exceeds the above-mentioned range, the overall viscosity of the epoxy resin composition may increase, thereby deteriorating the dispersibility with the filler, and the insulating layer may not be properly formed between the stator slot and the coil, thereby failing to provide sufficient insulating characteristics, which may lower product reliability.

[0036] Based on the total weight of the epoxy resin composition, the content of the dicyclopentadiene-type epoxy resin may be 1 to 20 wt%, for example, 1 to 10 wt%. If the content of the dicyclopentadiene-type epoxy resin is less than the above-mentioned range, high-temperature thermal decomposition characteristics may deteriorate, and if it exceeds the above-mentioned range, the content of the filler may be reduced, resulting in a deterioration in mechanical strength.

[0037]

[0038] Phenol aralkyl type epoxy resin

[0039] The epoxy resin composition of the present invention may include a phenol aralkyl type epoxy resin as the epoxy resin. The phenol aralkyl type epoxy resin forms a three-dimensional network structure after reacting with a curing agent and curing, thereby imparting strong and solid adhesion properties to an adherend and flame retardancy. The phenol aralkyl type epoxy resin has a structure based on a phenol skeleton and containing biphenyl in the middle, and has excellent hygroscopicity, toughness, oxidation resistance, and crack resistance. In addition, since it has a low crosslinking density, it forms a carbon layer (char) when burned at a high temperature, thereby blocking the transfer of heat and oxygen from the surroundings, thereby imparting flame retardancy.

[0040] The above phenol aralkyl type epoxy resin may be represented by the following formula 2.

[0041] [Chemical Formula 2]

[0042]

[0043] In the above formula, n is an integer from 1 to 10.

[0044] The epoxy equivalent of the above phenol aralkyl type epoxy resin may be 250 to 400 g / eq, for example, 270 to 290 g / eq. If the epoxy equivalent is less than the above-mentioned range, the flame retardant properties may be deteriorated, and if it exceeds the above-mentioned range, the mechanical properties may be deteriorated.

[0045] The viscosity (150° C.) of the above phenol aralkyl type epoxy resin may be 0.01 to 10 poise, for example, 0.05 to 3.0 poise. If the viscosity is less than the above-mentioned range, the flame retardant properties may deteriorate, and if it exceeds the above-mentioned range, the glass transition temperature (Tg) of the epoxy resin composition may be lowered and the mechanical properties may be deteriorated.

[0046] Based on the total weight of the epoxy resin composition, the content of the phenol aralkyl type epoxy resin may be 0.1 to 10 wt%, for example, 0.1 to 5 wt%. If the content of the phenol aralkyl type epoxy resin is less than the above-mentioned range, the flame retardant properties may be deteriorated, and if it exceeds the above-mentioned range, the mechanical properties and adhesion properties with metal may be deteriorated.

[0047] For example, the epoxy resin composition of the present invention may include a dicyclopentadiene-type epoxy resin, a phenol aralkyl-type epoxy resin, or a mixture thereof as the epoxy resin. The mixing ratio of the dicyclopentadiene-type epoxy resin and the phenol aralkyl-type epoxy resin may be a weight ratio of 0 to 100:100 to 0, for example, 10 to 50:1.

[0048]

[0049] Other epoxy resins

[0050] The epoxy resin composition of the present invention may further include other epoxy resins in addition to the dicyclopentadiene type epoxy resin and the phenol aralkyl type epoxy resin, in order to supplement the bonding strength, adhesive strength, etc. of the epoxy resin composition, within a range that does not impair the physical properties of the insulating material of the present invention.

[0051] 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-based epoxy resins, alicyclic epoxy resins, cresol novolac-based epoxy resins, biphenyl-based epoxy resins, naphthalene-based epoxy resins, polyfunctional epoxy resins, anthracene-based epoxy resins, non-condensed ring-based polycyclic structure epoxy resins, bisphenol fluorene-modified epoxy resins, and the like, and one or more of these may be further included.

[0052]

[0053] The total content of the dicyclopentadiene type epoxy resin, the phenol aralkyl type epoxy resin, and the other epoxy resins included in the epoxy resin composition according to the present invention may be 1 to 20 wt%, for example, 3 to 12 wt%, and as another example, 5 to 10 wt%, based on the total weight of the epoxy resin composition. If the total content of the dicyclopentadiene type epoxy resin, the phenol aralkyl type epoxy resin, and the other epoxy resins is less than the above-mentioned range, the respective components may not be adhered, coagulated, or combined during curing of the epoxy resin composition, which may cause cracks to occur or durability to deteriorate. If the total content exceeds the above-mentioned range, the resin components may be thermally decomposed upon exposure to high temperatures, which may increase the high-temperature mass loss rate, lower insulation, lower durability, and cause cracks to occur or damage may occur even with a slight external impact.

[0054]

[0055] hardener

[0056] The epoxy resin 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.

[0057] The above curing agent may be any curing agent known in the art that undergoes a curing reaction with an epoxy resin. For example, the curing agent may be a phenol-based compound having two or more phenolic hydroxyl groups in one molecule. For example, the curing agent may 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.

[0058] The above-mentioned curing agent may be one having a hydroxyl equivalent of 120 to 200 g / eq, for example, 160 to 180 g / eq. If the hydroxyl equivalent is less than the above-mentioned range, the adhesive strength of the epoxy resin composition may be reduced, and if it exceeds the above-mentioned range, the glass transition temperature (Tg) of the epoxy resin composition may be lowered and the mechanical properties may be deteriorated.

[0059] The above-mentioned hardener may be one having a viscosity (150°C) of 0.1 to 5 poise, for example, 0.5 to 2 poise. If the viscosity is less than the above-mentioned range, the adhesion of the epoxy resin composition may be reduced, and if it exceeds the above-mentioned range, the glass transition temperature (Tg) of the epoxy resin composition may be lowered and the mechanical properties may be deteriorated.

[0060] The above-mentioned hardener may be used with an electrical conductivity of 25 μs / cm or less. If the electrical conductivity exceeds the above-mentioned range, the electrical insulation properties may deteriorate.

[0061] The above-mentioned hardener may be used with a volatile content of 1% or less, for example, 0.2% or less. If the volatile content exceeds the above-mentioned range, high-temperature thermal decomposition characteristics may deteriorate.

[0062] Based on the total weight of the epoxy resin 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 moldability may be reduced, and if it exceeds the above-mentioned range, reliability and strength may be reduced due to increased moisture absorption.

[0063]

[0064] filler

[0065] The epoxy resin composition according to the present invention includes a filler. The filler imparts strength to the epoxy resin composition and serves to control flowability.

[0066] As the filler, any filler commonly used in the relevant technical field can be used without limitation. For example, inorganic fillers such as silica, silica nitride, alumina, aluminum nitride, and boron nitride can be used, and these can be used alone or in combination of two or more. The shape of the filler is not particularly limited, and both angular and spherical shapes can be used.

[0067] The above filler may include two types of fillers having different particle sizes. For example, the filler may include a first filler having an average particle size (D50) of 3 to 14 μm, for example, 7 to 14 μm, and a second filler having an average particle size (D50) of 14.5 to 30 μm, for example, 14.5 to 21.5 μm.

[0068] Based on the total weight of the epoxy resin composition, the content of the filler may be 50 to 95 wt%, for example, 81 to 90 wt%. If the content of the filler is less than the above-mentioned range, the moisture absorption in the cured product of the epoxy resin composition may increase, which may lower reliability. If the content of the resin is excessive and exposed to high temperatures, the resin may decompose, which may increase the high-temperature mass loss rate and lower insulation. If the content exceeds the above-mentioned range, fluidity may decrease, which may result in poor moldability.

[0069]

[0070] additives

[0071] The epoxy resin composition according to the present invention may further include additives commonly used in the relevant technical field, such as an adhesion enhancer, a release agent, a curing accelerator, a colorant, a flame retardant, etc., as needed.

[0072] Adhesion enhancers are used to improve organic-inorganic bonding and adhesion to metal substrates, and epoxy silane, amino silane, mercapto silane, acrylic silane, vinyl silane, etc. can be used. Release agents can be used such as both-terminal amine-modified silicone oil, paraffin wax, carnauba wax, polyethylene wax, ester wax, long-chain fatty acids, metal salts of long-chain fatty acids, etc. In addition, imidazole compounds, amine compounds, organic phosphine compounds, etc. can be used as curing accelerators to improve curing speed and workability. In addition, additives such as colorants (e.g., carbon black, Bengala, etc.) and flame retardants (e.g., metal hydroxide, etc.) for imparting color to the resin composition can be further included.

[0073] The above additives may be added within a content range that does not impair the physical properties of the epoxy resin 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 epoxy resin composition, but are not limited thereto.

[0074]

[0075] <Rotating electrical machine>

[0076] The present invention provides a rotating electric machine equipped with the aforementioned insulating material. The rotating electric machine may be a component for a vehicle.

[0077] For example, 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.

[0078] The insulating material according to the present invention has excellent insulating properties and heat resistance, and can be applied as an insulating material that provides insulating properties to rotating electric machines, such as electric vehicle motors, in which the rotational speed and the current applied to the stator increase as a large torque is required.

[0079]

[0080] 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.

[0081]

[0082] [Experimental Example 1-11]

[0083] Each component was mixed according to the composition described in Tables 1 and 2 below to prepare an epoxy resin composition for each experimental example.

[0084]

[0085]

[0086]

[0087]

[0088] Epoxy resin 1: Dicyclopentadiene (DCPD) type epoxy resin (EEW ​​259 g / eq, viscosity (150 ℃) 0.8 poise)

[0089] Epoxy resin 2: Phenol aralkyl type epoxy resin (EEW ​​274 g / eq, viscosity (150 ℃) 0.1 poise)

[0090] Epoxy resin 3: Ortho-cresol novolac type epoxy resin (EEW ​​208 g / eq, viscosity (150 ℃) 2.8 poise)

[0091] Epoxy resin 4: Bisphenol A type epoxy resin (EEW ​​191 g / eq, viscosity (150 ℃) 0.02 poise)

[0092] Curing agent: Phenol polymer with 1,4-bis(methoxymethyl)benzene (viscosity (150 ℃) 0.95 poise, electrical conductivity 9 ㎲ / cm, OH equivalent 170 g / eq, volatile matter 0.1%)

[0093] Filler: Silica (D50 7-14 ㎛_30 wt%, D50 14.5-21.5 ㎛_70 wt%)

[0094] Silane: Trimethoxy[3-(phenylamino)propyl]silane

[0095] Wax: Ester wax

[0096] Colorant: Carbon Black

[0097] Catalyst: Triphenylphosphine Imidazol

[0098] Flame retardant: (Carbonato)hexadecahydroxydialuminum-hexamnesium

[0099]

[0100] [Physical property evaluation]

[0101] The physical properties of the epoxy resin composition of each experimental example were measured using the following method, and the results are shown in Tables 3 and 4 below.

[0102]

[0103] Spiral flow (S / F)

[0104] The temperature of the mold press was set to 175 ℃, and the test was conducted under the following conditions at an actual mold temperature of 170±5 ℃.

[0105] - Transfer pressure: 1000±25 psi

[0106] - Transfer speed: 1-4 inch / sec

[0107] - Curing time: 120 sec

[0108] When measuring using a spiral flow measurement mold specified in ASTM D 3123-72, a sample was taken so that the cull thickness was 3±0.5 mm, and then the spiral flow value was measured.

[0109]

[0110] Gel Time (G / T)

[0111] After applying 2 g of the epoxy resin composition of each experimental example thinly using a spatula on a hot plate preheated to 170±3 ℃, the time until the film began to break down as curing began was measured.

[0112]

[0113] High temperature mass loss rate

[0114] Ten specimens measuring 30 mm in diameter x 2 mm in thickness were prepared using a transfer molding machine, and their weights (W0) were measured. One cycle involved heating in a 275°C drying oven for 24 hours and cooling to room temperature. The process was repeated n times, and the weight (W ncycle) was measured, and the high-temperature mass loss rate was calculated according to the following equation.

[0115] High temperature mass loss rate (%): [(W0- W ncycle ) / W0] X 100

[0116]

[0117] Adhesion (Cu)

[0118] The epoxy resin composition of each experimental example was molded into a cylindrical shape with a diameter of 5.5 mm on a Cu specimen, and the adhesion was measured using a die shear tester. The molding conditions were identical to those for the spiral flow measurement.

[0119]

[0120] Withstanding voltage test (leakage current evaluation)

[0121] A dielectric strength test was conducted on specimens that had completed five cycles, as used in evaluating high-temperature mass loss rates. Electrodes were connected across the thickness of each specimen, and a current of 2.2 kV was applied for 1 minute. A failure was assessed if the leakage current exceeded 50 mA during the 1-minute application of 2.2 kV, and a pass was assessed if the leakage current was less than 50 mA.

[0122]

[0123]

[0124]

[0125] As shown in Tables 3 and 4 above, the insulating materials of Experimental Examples 1-7, in which the epoxy resin compositions according to the present invention were cured with a high temperature mass loss rate of less than 2 wt%, exhibited excellent adhesion and insulation properties. On the other hand, the insulating materials of Experimental Examples 8-11, in which the high temperature mass loss rate was 2 wt% or more, exhibited very poor insulation properties with low insulation resistance and a generated leakage current of 50 mA or more.

[0126]

[0127] The present invention provides an insulating material having excellent insulation properties and heat resistance. The present invention also provides a rotating electric machine equipped with the insulating material.

Claims

1. An insulating material formed by curing an epoxy resin composition containing an epoxy resin, a hardener, and a filler, which is provided between a slot and a coil in a motor stator. Insulating material with a high temperature mass loss rate of less than 2.0 wt% when performing 5 cycles of static and exposure for 24 hours in a 275 ℃ oven: High temperature mass loss rate (%) = [(W0- W 5cycle ) / W0] X 100 In the above formula, W0 is the mass of the cured insulation, W 5cycle is the mass of the insulation after 5 cycles.

2. In the first paragraph, the epoxy resin includes a dicyclopentadiene type epoxy resin, An insulating material having an epoxy equivalent of 200 to 300 g / eq of the above dicyclopentadiene type epoxy resin and a viscosity (150 ℃) of 0.1 to 10 poise.

3. In the first paragraph, the epoxy resin comprises a phenol aralkyl type epoxy resin, An insulating material having an epoxy equivalent of 250 to 400 g / eq of the above phenol aralkyl type epoxy resin and a viscosity (150 ℃) of 0.01 to 10 poise.

4. In the first paragraph, the epoxy resin comprises a dicyclopentadiene type epoxy resin, a phenol aralkyl type epoxy resin, or a mixture thereof, An insulating material in which the mixing ratio of the above dicyclopentadiene type epoxy resin and the above phenol aralkyl type epoxy resin is 0 to 100:100 to 1 by weight.

5. In the first paragraph, the curing agent includes 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. An insulating material having a hydroxyl equivalent of the above-mentioned hardener of 120 to 200 g / eq, a viscosity (150°C) of 0.1 to 5 poise, an electrical conductivity of 25 μs / cm or less, and a volatile content of 1% or less.

6. In the fourth paragraph, an insulating material comprising 1 to 20 wt% of the dicyclopentadiene type epoxy resin, 0.1 to 10 wt% of the phenol aralkyl type epoxy resin, 0.1 to 15 wt% of the curing agent, and 50 to 95 wt% of the filler, based on the total weight of the epoxy resin composition.

7. Contains a rotor and a stator, The above stator has a circular stator core having a plurality of slots in the circumferential direction of the inner surface, A coil is wound in the above slot, A rotating electric machine having an insulating material according to any one of claims 1 to 6 between the slot and the coil.

Images