KR20210074806A - Cured body and the manufacturing method thereof - Google Patents

Abstract

The present application relates to a cured body and a manufacturing method thereof, wherein the cured body of the present application may have improved curing properties, for example, improved dielectric breakdown strength and the manufacturing method of the cured body of the present application can rapidly manufacture the cured body having improved curing properties.

Description

Cured body and the manufacturing method thereof

The present application relates to a cured product and a method for manufacturing the same.

Various methods are known for preparing a cured product by curing a curable resin, specifically, a thermosetting resin. An example of such a method may be a method of curing the curable composition including the curable resin by applying hot air using a heating device such as an oven. However, in the hot air curing method, a difference in the degree of hardening inside and outside the hardening body inevitably occurs, and there is a problem in that mechanical properties and insulating properties of the hardening body are deteriorated. In addition, when a heating device such as an oven is used, the curing time is inevitably long, so there is a limit to mass production of the cured product. A method of curing at a relatively low temperature was considered in order to reduce the difference in the degree of curing between the inside and outside of the cured body, but there was a problem in that the physical properties of the cured body change significantly with time. In addition, although a method of increasing the size of equipment such as an oven has been considered to improve productivity, it is not appropriate from the viewpoint of process economy, and there is a problem of inefficiency in terms of space and energy efficiency.

Various curing methods have been considered in order to solve the problems of the above-described method such as oven heating. For example, a method of curing the resin by irradiating light such as ultraviolet rays has been considered. However, in this method, only the surface of the hardened body can be rapidly hardened, there was still a difference in the degree of hardening inside and out of the hardened body, and there was a problem that the curable resin was not hardened sufficiently, so that unreacted substances remained, and additional heat treatment was required. There was also a problem.

As another example of the other curing method, a method of curing the curable composition through heating (induction heating) by applying an electromagnetic field to the curable composition. However, in order to secure the advantages of this method, when the substrate to which the curable composition is applied must be limited to a metal, it is difficult to precisely control the degree of heating, and when different types of substrates are applied There were problems such as a problem of heat conduction, expansion and/or shrinkage between the substrates, and a difference in the degree of curing inside and outside the cured body.

In the present application, it is an object of the present application to provide a cured body capable of having improved hardening properties, for example, improved dielectric breakdown strength by applying a magnetic powder oriented in a specific direction.

In the present application, another object of the present application is to provide a method of manufacturing a cured product capable of rapidly manufacturing a cured product having improved curing properties by orienting magnetic powder in a specific direction.

If the measured temperature and/or pressure affect the physical properties among the physical properties mentioned in the present application, the physical properties mean properties measured at room temperature and/or pressure unless otherwise specified.

In the present application, the term “room temperature” is a natural temperature that is not particularly heated and/or reduced, and may be any temperature within the range of about 10° C. to 30° C., 25° C. or 23° C. or so.

In the present application, the term “atmospheric pressure” refers to a pressure when not particularly pressurized and/or depressurized, and may be usually about 1 atm, such as atmospheric pressure.

This application relates to a cured body. The cured product refers to a cured product of a resin, that is, a material or a composite formed by curing the curable resin. Accordingly, the cured product of the present application includes at least a cured product of a resin, preferably a cured product of a curable resin (thermosetting or photocuring, etc.). In the above, the curable resin may refer to a polymer that can be cured by external force, for example, application of heat or irradiation of light.

The cured product of the present application includes a cured resin or cured product of resin and magnetic powder. The magnetic powder may be present in a cured product of the resin. Therefore, in the cured product of the present application, the magnetic powder may be selected to exhibit an appropriate degree of dispersion in the cured resin material. As will be described later, in the present application, by aligning the magnetic powder or a specific material in the magnetic powder in a specific direction, it is possible to provide a cured body having excellent physical properties, particularly insulation properties, required for the cured body. Specifically, the cured body of the present application may have an improved dielectric breakdown strength. The dielectric breakdown strength is a representative physical property that can objectify the insulation of a hardened body, and is known to mean the intensity (strength) obtained by converting the voltage required to destroy a specific hardened body according to a specific rule.

The magnetic powder contains at least a magnetic material. In the above, the magnetic material is a material exhibiting magnetism, and may refer to a material capable of generating heat when an electromagnetic field having a predetermined intensity is applied from the outside. In the present application, in some cases, the magnetic material may also be referred to as a “nano magnetic material”, which may mean that the magnetic material has a size of a nanometer unit, specifically, a size of several nanometers to several hundreds of nanometers.

In the cured body of the present application, the magnetic body is oriented in a specific direction. According to such an orientation form, the cured body of the present application may have excellent insulating properties, specifically, excellent dielectric breakdown strength. In general, when a cured product is manufactured by mixing a curable resin and a magnetic powder, since the magnetic material exhibits higher electrical conductivity than the curable resin, the dielectric breakdown strength of the cured product is determined by drying the curable resin with hot air without mixing the magnetic powder. It appears lower than the hardened|cured hardening body.

However, the inventors of the present invention have arrived at the present invention after confirming that when the magnetic material contained in the magnetic powder in the hardening body is oriented in a specific direction as described in the present application, it shows an improved dielectric breakdown strength compared to the prior art. Specifically, in the present application, when the magnetic material is oriented in a direction capable of blocking the movement of electrons of a current applied to measure the dielectric breakdown strength, it may have an improved dielectric breakdown strength. In order to block electrons moving in the current applied to measure the dielectric breakdown strength, it is appropriate to be substantially perpendicular to the direction of the applied current.

On the other hand, the current applied to measure the dielectric breakdown strength is approximately parallel to or approximately perpendicular to the direction of gravity. Accordingly, the magnetic body is also oriented along the above-mentioned direction. That is, in the cured product of the present application, the magnetic material is oriented in a direction approximately parallel to a direction parallel to the direction of gravity or approximately perpendicular to a direction parallel to the direction of gravity in the cured resin material. Specifically, the magnetic material has a direction parallel to the direction of gravity in the cured resin and an angle within a range of -10 degrees to 10 degrees (sometimes also referred to as a “first angle”) or within a range of 80 degrees to 100 degrees. It is oriented to form an angle (sometimes referred to as a “second angle”).

The angle formed by the two axes, lines, or planes referred to in the present application may have different signs depending on the case, and the clockwise angle from the point at which the measurement is a reference is a positive number, and the counterclockwise angle is a positive number. can be expressed as a negative number.

The first angle may be, in another example, -7 degrees or more, -5 degrees or more, -3 degrees or more, or -1 degrees or more, and 7 degrees or less, 5 degrees or less, 3 degrees or less, or 1 degree or less, or It may be on the order of 0 degrees.

In another example, the second angle may be 83 degrees or more, 85 degrees or more, 87 degrees or more, or 89 degrees or more, 97 degrees or less, 95 degrees or less, 93 degrees or less, or 91 degrees or less, or about 90 degrees. can

On the other hand, in most of the dielectric breakdown strength measurement methods, including the methods mentioned in the embodiments to be described later, since the direction of the current applied for the measurement (also referred to as the conduction direction) is parallel to the direction of gravity, conduction as described above In order to increase insulation by blocking the movement of electrons flowing in the direction, it may be appropriate for the magnetic material to be oriented at a second angle. That is, in the cured resin, the magnetic material has an angle within a range of 80 to 100 degrees with the axis in a direction parallel to the direction of gravity, specifically 83 degrees or more, 85 degrees or more, 87 degrees or more, or 89 degrees or more, 97 It may be appropriate to be oriented to form an angle of less than or equal to 95 degrees, less than 95 degrees, less than 93 degrees, or less than 91 degrees, or approximately 90 degrees.

A method of aligning the magnetic material in a specific direction as described above is not particularly limited, and for example, the magnetic material may be oriented in the same direction according to a method to be described later.

The magnetic material may have a size of nanometers. Therefore, the magnetic powder, which is a composite including the magnetic material, may exist in a powder form. In the above, the magnetic powder may mean a powder capable of generating heat when an electromagnetic field is applied by including the magnetic material. The magnetic particles refer to materials selected to generate heat by a magnetic reversal vibration phenomenon through an external alternating magnetic field.

In the present application, the characteristics of the applied magnetic material in terms of securing the improved insulating properties of the cured body may also be further adjusted. The magnetic body may be a composite including magnetic particles and a surface treatment agent introduced to the surface of the magnetic particles. In the present application, a magnetic body suitable for the purpose of the present application may be formed through selection and combination of appropriate magnetic particles and/or a surface treatment agent and control of their composition.

As the magnetic particles included in the magnetic material, two or more crystals, specifically, multi-magnetic domain type magnetic particles including two or more magnetic domains may be applied. The multi-domain magnetic particle may be a magnetic particle in which the magnetic domains are randomly arranged when an external magnetic field is not applied, and can be magnetized along the direction of the applied magnetic field when an external magnetic field is applied. . In the above, the meaning that the magnetic domains are irregularly arranged may mean that the directions of magnetic forces present in the magnetic domains are different and are not aligned, and in this case, the net value of the magnetization is substantially 0. It may exist in a non-magnetic state in close proximity. The magnetic particle may be a super-paramagnetic particle, but is not limited thereto.

Whether the magnetic particle is a multi-domain type magnetic particle can be generally confirmed through the particle diameter of the magnetic particle. For example, if the magnetic particle has a particle _{diameter of D s} or greater satisfying Equation 1 below, it can be inferred that the magnetic particle has a multi-domain:

[Formula 1]

In Equation 1, μ ₀ is a magnetic permittivity constant in vacuum (1.26Х ^-6 H/m), and Ms is the saturation magnetization of magnetic particles (unit: A/m or emu/g) ), where A is the exchange stiffness (unit: J/m) of the magnetic particle, and a is the lattice constant (unit: m) of the magnetic particle.

In Equation 1, variables except for the magnetic permeability constant under vacuum, that is, the saturation magnetization, exchange stiffness, and lattice constant of the magnetic particle may be changed according to specific types constituting the magnetic particle. Therefore, it is possible to form magnetic particles having multi-domains by checking the respective numerical values for the magnetic particles to be applied, and then controlling the size of the magnetic particles to be greater than or equal to _{D s obtained by substituting the numerical values into Equation 1 above.}

_{In general, magnetic particles having a particle diameter of D s} or more obtained according to Equation 1 are multi-domained, and since the magnetic particles of the present application are multi-domain magnetic particles, the magnetic particles applied in the present application are at least D _s or more. have a particle size Usually, as the particle diameter of the magnetic particles exceeds D _s , the coercive force of the corresponding magnetic particles tends to decrease, and the magnetic particles applied in the present application may have a particle diameter within a range in which the magnetic powder to which it is applied can have the coercive force described later. .

Since the magnetic particles as described above behave similarly to those without magnetism when no external magnetic field is applied, when a magnetic material including the magnetic particles is applied to, for example, a composition, the magnetic material is uniformly dispersed in the composition. It may exist in an existing state.

The magnetic particles do not generate heat by so-called eddy current or hysteresis loss, but the hysteresis loss of the magnetic particles itself is small, and only a saturation magnetization value is substantially present. Thus, it can be adjusted to generate vibrational heat. For example, when an external electromagnetic field is applied, the magnetic particles vibrate by a coercive force thereof, and as a result, heat may be generated.

The magnetic particles include two or more magnetic domains. The term “magnetic domain” as used in the present application generally refers to a region in which magnetization directions are distinguished from each other in a magnetic particle. Such a magnetic domain may constitute a crystal of the magnetic particle within the magnetic particle. That is, the magnetic particles include two or more crystals. In the present application, when the magnetic particles have two or more magnetic domains, the magnetic domains are strongly magnetized by an externally applied alternating magnetic field to generate vibrational heat, and when the applied magnetic field is removed, the magnetic domains return to their original state, thereby Magnetic particles having a low residual magnetization of hysteresis loss may be formed.

In the present application, the size of the crystals included in the magnetic particles and the average particle diameter of the particles are adjusted within a specific range, the magnetic particles are configured in a multi-domain type, and a surface treatment agent is added to the surface of the particles together with the magnetic particles. By introducing it, the cured body has the above-described insulating properties and cured physical properties such as an improved degree of curing at the same time.

The magnetic particles include crystals whose size is within a specific range. In addition, the magnetic particles include two or more of the magnetic domains. Specifically, the magnetic particles may be clusters formed by the plurality of crystals. The size of the crystals included in the magnetic particles is in the range of 10 nm to 40 nm, respectively. In another example, the size of the crystal may be 15 nm or more or 20 nm or more, and 37 nm or less or 35 nm or less. In addition, when the average size of the magnetic particles is constant and the size of the crystals is within the above range, the higher the size of the crystals, the higher the calorific value of the magnetic material or magnetic powder including the magnetic particles.

When the sizes of the plurality of crystals present in the magnetic particles are not constant, the sizes of the crystals may mean the maximum size, the minimum size, or the average size of the magnetic domains. The size of the crystal may be measured through X-ray diffraction analysis of the magnetic particles or magnetic powder, and the method described in Examples to be described later may be applied as a specific measurement method.

In the present application, by adjusting the average particle diameter of the magnetic particles having two or more crystals having a size in the above range within a specific range, the cured body has cured physical properties such as an improved degree of curing in addition to the above-described insulating properties. Specifically, in the present application, the average particle diameter of the magnetic particles is adjusted within the range of 20 nm to 300 nm. In another example, the average particle diameter of the magnetic particles may be 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, 70 nm or more, or 80 nm or more, and 290 nm or less, 280 nm or less, 270 nm or less, 260 nm or less, 250 nm or less, 240 nm or less, 230 nm or less, 220 nm or less, 210 nm or less, 200 nm or less, 190 nm or less, 180 nm or less, 170 nm or less, 160 nm or less, 150 nm or less, 140 nm or less , 130 nm or less or 120 nm or less.

A method of measuring the average particle diameter of the magnetic particles is not particularly limited. For example, an average particle diameter of the magnetic particles may be measured by preparing a magnetic body including the magnetic particles or a magnetic powder including the same, and then analyzing an electron micrograph taken of the magnetic body or the magnetic powder.

The magnetic body includes the above conditions, specifically, magnetic particles and a surface treatment agent introduced to the surface of the magnetic particles, and the magnetic particles contain two or more crystals and/or magnetic domains whose sizes are within the above range, When the average particle diameter of the magnetic particles satisfies the condition within the above range, the magnetic material or the magnetic powder containing the magnetic material can generate heat with a high calorific value, and at the same time, there is an advantage that the calorific value can be maintained uniformly. Specifically, the magnetic material satisfying the above conditions may have an appropriate number of magnetic domains and an appropriate size of coercive force, and as a result, may generate vibrational heat when an electromagnetic field is applied through a low coercive force and a plurality of magnetic domains, and the magnetic particles themselves Since it is possible to allow only the saturation magnetization value to exist while reducing the hysteresis loss of , stable and uniform heat generation may be possible when an electromagnetic field is applied. In addition, since the present application is a cured product including such magnetic powder, there is an advantage in that cured physical properties are excellent.

On the other hand, when the magnetic material in the magnetic powder does not satisfy any one of the above conditions, for example, the magnetic material does not contain a surface treatment agent, or even if the magnetic material contains a surface treatment agent, the surface treatment agent is not the magnetic particles. If the crystals are first introduced to the surface of the constituting crystals or have particle characteristics outside the range of the above-mentioned crystal size and the average particle diameter of the magnetic particles, a desired level of hardening properties may not be secured.

In one example, the ratio of the crystal size of the magnetic particles to the average particle diameter of the magnetic particles may also be appropriately adjusted from the viewpoint of uniformly securing an appropriate amount of heat. For example, in the magnetic material, the ratio (B/A) of the crystal size (A) of the magnetic particles to the average particle diameter (B) of the magnetic particles may be in the range of 1.5 to 10. The ratio may be 2 or more or 2.5 or more in another example, and 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3.5 or less, or 3.3 or less.

As long as the magnetic particles can generate heat through electromagnetic induction heating, the type thereof is not particularly limited. For example, the magnetic particle may be represented by the following Chemical Formula 1:

[Formula 1]

[Formula 1]

MX _a O _b

In Formula 1, M is a metal or metal oxide, X includes Fe, Mn, Co, Ni or Zn, |a × c| = |b × d|, where c is the cation charge of X, and d is the anion charge of oxygen. In one example, M in Formula 1 is Fe, Mn, Mg, Ca, Zn, Cu, Co, Sr, Si, Ni, Ba, Cs, K, Ra, Rb, Be, Li, Y, B or their It may be an oxide. For example, when X _a O _b is Fe ₂ O ₃ , c may be +3 and d may be -2. Also, for example, when X _a O _b is Fe ₃ O ₄ , _{it may be expressed as FeOFe 2} O ₃ , so c may be +2 and +3, respectively, and d may be -2. The magnetic particle of the present application is not particularly limited as long as it satisfies Chemical Formula 1, and may be _{, for example, FeOFe 2} O _{3 .}

As the magnetic particles, the compound of Formula 1 may be applied alone, or a compound doped with an inorganic material may be applied to the compound of Formula 1 above. The inorganic material may include monovalent to trivalent cationic metals or oxides thereof, and two or more cationic metals may be used.

As described above, the magnetic particles may exist in a form in which magnetic domains (or crystals) are clustered. Specifically, the magnetic particles include a plurality of crystals having a size within a specific range as described above, and these crystals may be clustered to form the magnetic particles. That is, the magnetic particles may exist in a form in which a magnetic particle cluster is formed in the magnetic body. In this case, it is possible to prevent a decrease in the amount of heat generated by aggregation between the magnetic particles.

In the magnetic body, the magnetic particles are surface-treated with an appropriate surface treatment agent. The surface treatment of the magnetic particles may be performed using a compound (surface treating agent) that may be introduced to the surface of the magnetic particles.

In the present application, the terms “introduction”, “anchoring”, “interaction” or “bonding” used while referring to the surface treatment of the magnetic material refer to the bonding between the magnetic particles and the surface treatment agent or between the surface treatment agents. This means that it is formed. And in the above, the bond may be used to include all bonds known to connect two components to each other, such as a covalent bond, an ionic bond, a hydrogen bond, a coordination bond, and/or a van der Waals bond.

In one example, as the surface treatment agent, a precursor of the magnetic particles or a compound having a functional group capable of binding to the surface of the magnetic particles with a strong bonding force may be applied. As the compound having the functional group, a compound having a phosphoric acid group, a carboxyl group, a sulfonic acid group, an amino group and/or a cyano group can be applied. have. Accordingly, the magnetic particles or precursors of the magnetic particles may be surface-treated with a material having the above functional group, that is, a surface treatment agent.

As a compound that can be applied as a surface treatment agent in the present application, a polyol-based compound, a polysiloxane-based compound, an alkyl phosphoric acid-based surface treatment agent (eg, a compound of Formula A below), an alkyl carboxylic acid )-based surface treatment agent (for example, a compound of Formula B below), sulfonic acid-based surface treatment agent, other acid compounds containing long-chain alkyl groups, acrylic copolymers containing acidic functional groups or amino groups, aromatic acid-based surface treatment agents , a block copolymer including an acidic functional group or an amino group may be applied.

[Formula A]

[Formula B]

[Formula C]

In Formulas A to C, R ₁ to R ₃ are each independently an alkyl group, an arylalkyl group, an alkoxy group, or an arylalkoxy group.

An alkyl group or an alkoxy group having 6 to 24 carbon atoms may be exemplified as the alkyl group or alkoxy group that may be included in Formulas A to C. In addition, the number of carbon atoms of the alkyl group or the alkoxy group is 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more in another example. or more, 17 or more, 18 or more, 19 or more, 20 or more, 21 or more, 22 or more, or 23 or more, or 23 or less, 22 or less, 21 or less, 20 or less, 19 or more Below, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, 9 or less, 8 or less, or 7 or less may be

As the alkyl group or alkoxy group that may be included in Formulas A to C, an aryl group having 6 to 13 carbon atoms may be exemplified, and for example, a benzyl group or a phenyl group may be applied.

In another example, the surface treatment agent includes (a) a phosphoric acid ester salt of an optionally fatty acid-modified or alkoxylated (especially ethoxylated) polyamine, a phosphoric acid ester salt of an epoxide-polyamine adduct, an acrylic containing an amino group phosphoric acid ester salts of oligomers or polymers containing amino groups, such as phosphoric acid ester salts of late or methacrylate copolymers or phosphoric acid ester salts of acrylate-polyamine adducts; (b) monoesters or diesters of phosphates with alkyl, aryl, aralkyl, or alkylaryl alkoxylates, such as nonylphenol ethoxylates, isotridecyl alcohol ethoxylates, butanol-started alkylene oxide polyethers monoesters of phosphoric acid, such as monoesters or diesters of phosphoric acid with polyesters (e.g. lactone polyesters such as caprolactone polyesters or caprolactone/valerolactone mixed polyesters) or diesters; (c) acidic dicarboxy monoesters with alkyl, aryl, aralkyl, or alkylaryl alkoxylates (especially those of succinic, maleic or phthalic acids) such as nonylphenol ethoxylates, isotridecyl alcohol ethoxylates , or butanol-initiated alkylene oxide polyethers) and the like); (d) polyurethane-polyamine adducts; (e) polyalkoxylated monoamines or diamines (such as ethoxylated oleylamines or alkoxylated ethylenediamines) or (f) reaction products of monoamines, diamines, polyamines, amino alcohols with unsaturated fatty acids and unsaturated 1,2-diamines Carboxylic acids and their anhydrides and their salts and reaction products with alcohols and/or amines and the like can also be applied.

Such surface treatment agents are known as commercially available products, for example, BYK-220 S, BYK-P 9908, BYK-9076, BYK-9077, BYK-P 104, BYK-P 104 S, BYK-P 105, BYK-W 9010, BYK-W 920, BYK-W 935, BYK-W 940, BYK-W 960, BYK-W 965, BYK-W 966, BYK-W 975, BYK-W 980, BYK-W 990, BYK-W 995, BYK-W 996, BYKUMEN, BYKJET 9131, LACTIMON, ANTI-TERRA-202, ANTI-TERRA-203, ANTI-TERRA-204, ANTI-TERRA-205, ANTI-TERRA-206, ANTI -TERRA-207, ANTI-TERRA-U 100, ANTI-TERRA-U 80, ANTI-TERRA-U, LP-N-21201, LP-N-6918, DISPERBYK, DISPERBYK-101, DISPERBYK-102, DISPERBYK-103 , DISPERBYK-106, DISPERBYK-107, DISPERBYK-108, DISPERBYK-109, DISPERBYK-110, DISPERBYK-111, DISPERBYK-112, DISPERBYK-115, DISPERBYK-116, DISPERBYK-118, DISPERBYK-130, DISPERBYK-140 -142, DISPERBYK-145, DISPERBYK-160, DISPERBYK-161, DISPERBYK-162, DISPERBYK-163, DISPERBYK-164, DISPERBYK-165, DISPERBYK-166, DISPERBYK-167, DISPERBYK-168, DISPERBYK-169, DISPERBYK-170 , DISPERBYK-171, DISPERBYK-174, DISPERBYK-176, DISPERBYK-180, DISPERBYK-181, DISPERBYK-182, DISPERBYK-183, DISPERBYK-18 4, DISPERBYK-185, DISPERBYK-187, DISPERBYK-190, DISPERBYK-191, DISPERBYK-192, DISPERBYK-193, DISPERBYK-194, DISPERBYK-2000, DISPERBYK-2001, DISPERBYK-2008, DISPERBYK-2009, DISPERBYK-2010 DISPERBYK-2020, DISPERBYK-2025, DISPERBYK-2050, DISPERBYK-2070, DISPERBYK-2090, DISPERBYK-2091, DISPERBYK-2095, DISPERBYK-2096, DISPERBYK-2150, DISPERBYK-2151, DISPERBYK-2152, DISPERBYK-2155, 2163, DISPERBYK-2164, DISPERBLAST-1010, DISPERBLAST-1011, DISPERBLAST-1012, DISPERBLAST-1018 or a surface treatment agent known by a product name such as DISPERBLAST-I, DISPERBLAST-P, etc. (BYK-Chemie of the bezel) may be used.

For an appropriate surface treatment effect, as the surface treatment agent, an acid value within the range of 10 to 400 mgKOH/g or a surface treatment agent having an amine value within the range of 5 to 400 mgKOH/g may be used.

In another example, the acid value of the surface treatment agent is about 20 mgKOH/g or more, 30 mgKOH/g or more, 40 mgKOH/g or more, 50 mgKOH/g or more, 60 mgKOH/g or more, 70 mgKOH/g or more, 80 mgKOH/g or more, or 90 mgKOH/g or more. or more, or about 390 mgKOH/g or less, 380 mgKOH/g or less, 370 mgKOH/g or less, 360 mgKOH/g or less, 350 mgKOH/g or less, 340 mgKOH/g or less, 330 mgKOH/g or less, 320 mgKOH/g or less, 310 mgKOH/g or less, 300 mgKOH or less /g or less, 290 mgKOH/g or less, 280 mgKOH/g or less, 270 mgKOH/g or less, 260 mgKOH/g or less, 250 mgKOH/g or less, 240 mgKOH/g or less, 230 mgKOH/g or less, 220 mgKOH/g or less, 210 mgKOH/g or less, 200 mgKOH or less /g or less, 190 mgKOH/g or less, 180 mgKOH/g or less, 170 mgKOH/g or less, 160 mgKOH/g or less, 150 mgKOH/g or less, 140 mgKOH/g or less, 130 mgKOH/g or less, 120 mgKOH/g or less, 110 mgKOH/g or less, or It may be on the order of 100 mgKOH/g or less.

In another example, the amine value of the surface treatment agent is about 10 mgKOH/g or more, about 15 mgKOH/g or more, about 20 mgKOH/g or more, 30 mgKOH/g or more, 40 mgKOH/g or more, 50 mgKOH/g or more, 60 mgKOH/g or more, 70 mgKOH /g or more, 80 mgKOH/g or more, or 90 mgKOH/g or more, or about 390 mgKOH/g or less, 380 mgKOH/g or less, 370 mgKOH/g or less, 360 mgKOH/g or less, 350 mgKOH/g or less, 340 mgKOH/g or less, 330 mgKOH/g or less g or less, 320 mgKOH/g or less, 310 mgKOH/g or less, 300 mgKOH/g or less, 290 mgKOH/g or less, 280 mgKOH/g or less, 270 mgKOH/g or less, 260 mgKOH/g or less, 250 mgKOH/g or less, 240 mgKOH/g or less, 230 mgKOH/g or less g or less, 220 mgKOH/g or less, 210 mgKOH/g or less, 200 mgKOH/g or less, 190 mgKOH/g or less, 180 mgKOH/g or less, 170 mgKOH/g or less, 160 mgKOH/g or less, 150 mgKOH/g or less, 140 mgKOH/g or less, 130 mgKOH/g or less g or less, 120 mgKOH/g or less, 110 mgKOH/g or less, or 100 mgKOH/g or less.

In the present specification, the term amine _{value is a value obtained by titrating an amino group (-NH 2} , -NHR or -NR ₂ ) included in the surface treatment agent with KOH and dividing it by the KOH consumption (a value expressed in mg of the amount of KOH titrated per 1 g of the surface treatment agent) ) means

In addition, the above refers to a value obtained by titrating the acid group (-COOH) possessed by the surface treatment agent with KOH and dividing it by the KOH consumption (a number expressed in mg of the amount of KOH titrated per 1 g of the surface treatment agent).

The acid value can be measured by dissolving the sample in a solvent (a mixed solvent of diethyl ether and ethanol volume ratio (diethyl ether: ethanol) of 2:1) and using an automatic potentiometric titrator (Mettler, G10S). Potentiometric titration is performed with an ethanol solution (potassium hydroxide ethanol solution) in which potassium hydroxide is dissolved so that the concentration becomes about 0.1 mol/l with respect to the sample, and the amount of the potassium hydroxide ethanol solution required to neutralize the sample is measured. Equation A can be used to calculate the acid number.

[Formula A]

Acid value = (B×f×5.611)/S

In Equation A, B is the amount (unit: mL) of the potassium hydroxide ethanol solution used for titration, f is the factor of 0.1 mol/L potassium hydroxide ethanol solution, and S is the mass (g) of the solid content of the sample.

The amine value (mgKOH / g) is put in an amount of about 0.5 g of the sample in a flask, dissolved in neutralized acetone (Acetone), cooled the solution, bromophenol blue (Bromophenol blue) indicator After titration with 0.1N HCl until it turns from blue to yellow using

[Formula B]

Amine value (mgKOH/g) = mol 0.1N HCl×100×5.61/sample weight×NV

In Equation B, NV is non-volatile, that is, as a solid content, it can be obtained in the following way.

After weighing the sample in an amount of about 0.8 to 1.0 g on a 7.5 cm Diameter Tin lid, spreading it evenly, and drying it in an air circulator drying oven at 125° C. for 60 minutes, it can be obtained by the following formula C.

[Formula C]

NV (unit: %) = final weight (weight after drying) / initial weight (weight before drying) Х 100

Meanwhile, in order to secure desired physical properties (viscosity, etc.), it may be appropriate that the surface treatment agent forming a bond with the magnetic particles is a compound having a weight average molecular weight (Mw) of about 20,000 or less. In the present application, the term "weight average molecular weight" is a standard polystyrene conversion value measured by Gel Permeation Chromatograph (GPC), and may simply be referred to as molecular weight unless otherwise specified. In addition, the unit of the molecular weight may be g/mol.

The molecular weight (weight average molecular weight) of the surface treatment agent is about 19,000 or less, 18,000 or less, 17,000 or less, 16,000 or less, 15,000 or less, 14,000 or less, 13,000 or less, 12,000 or less, 11,000 or less, 10,000 or less, 9,000 or less, 8,000 or less in another example. , 7,000 or less, 6,000 or less, 5,000 or less, 4,000 or less, 3,000 or less, 2,000 or less, or 1,000 or less, or 100 or more, 200 or more, 300 or more, 400 or more, 500 or more, 600 or more, 700 or more, 800 or more, 900 or more. It may be more than or equal to 1,000 or more. In the present application, although it may vary depending on the type of the applied surface treatment agent, the higher the molecular weight of the surface treatment agent applied within the above range, the larger the size of the crystals constituting the magnetic particles may tend to decrease.

In the present application, a method of interacting the functional group with magnetic particles present in a compound having a specific functional group, specifically, an anchoring functional group is applied, or when the surface treatment agent does not have the functional group, a known chemical method The magnetic body may be formed by introducing the functional group into the surface treatment agent and then interacting with the magnetic particles.

The proportion of the surface treatment agent in the magnetic body is not particularly limited, and may be added to an extent capable of producing a magnetic body capable of satisfying the aforementioned conditions, for example, the size of magnetic domains and/or the average particle diameter of magnetic particles. For example, the surface treatment agent may be included in a ratio within the range of 0.01 parts by weight to 30 parts by weight based on 100 parts by weight of the magnetic particles in the magnetic material. Under this ratio, a magnetic material having a desired exothermic property can be obtained. Unless otherwise specified in the present application, the unit “parts by weight” means the ratio of the weight between each component. In another example, the ratio may be 0.1 parts by weight or more, 1 part by weight or more, 2 parts by weight or more, 3 parts by weight or more, or 4 parts by weight or more, and 27 parts by weight or less, 25 parts by weight or less, 23 parts by weight or less, 21 It may be less than or equal to 20 parts by weight or less than 20 parts by weight. On the other hand, since the ratio of the surface treatment agent does not significantly affect the average particle diameter of the previously formed magnetic particles, when the ratio of the surface treatment agent exceeds the appropriate range, specifically, even if the ratio exceeds the above range, the size of magnetic particles, etc. It does not affect the physical properties.

A method of surface-treating the magnetic particles with the surface treatment agent to obtain the magnetic body is not particularly limited. For example, an interaction between the magnetic particles and the surface treatment agent is induced by mixing the magnetic particles and the surface treatment agent under an appropriate environment such as the presence of a solvent, and between the magnetic particles and the surface treatment agent or between the surface treatment agent can form a bond. Such a surface treatment agent may be present on the surface of the magnetic particles, specifically around the magnetic particles. In addition, the magnetic material may be manufactured by another method to be described later.

The magnetic particles may be additionally surface-treated. In this case, the above-mentioned surface treatment agent may be referred to as a primary surface treatment agent, and the surface treatment agent applied for additional surface treatment may be referred to as a secondary surface treatment agent. In one example, the magnetic material may further include the surface treatment agent (primary surface treatment agent) or a secondary surface treatment agent forming a bond with the magnetic particles. That is, when the magnetic material further includes a secondary surface treatment agent, the secondary surface treatment agent may be introduced to the surface of the magnetic particles and/or to the surface of the primary surface treatment agent treated on the surface of the magnetic particles. . This secondary surface treatment agent is generally applied to impart dispersion stability, cohesiveness, and anti-settling properties, etc. to the magnetic body, rather than controlling the particle properties of the magnetic particles constituting the magnetic body. In addition, the properties of the secondary surface treatment agent may be suitably changed according to the function of the material and compatibility with the material that can be mixed with the magnetic body.

A polymer compound may be used as the secondary surface treatment agent. For example, as the secondary surface treatment agent, a high molecular weight compound having a molecular weight (weight average molecular weight) in the range of about 1,000 to 500,000 may be applied. When the secondary surface treatment agent is a polymer compound, its molecular weight (Mw) is about 1500 or more, 2000 or more, 2500 or more, 3000 or more, 3500 or more, 4000 or more, 4500 or more, 5000 or more, 5500 or more, 6000 or more in another example. , 6500 or more, 7000 or more, 7500 or more, 8000 or more, 8500 or more, 9000 or more, 9500 or more, 10000 or more, 12000 or more, 14000 or more, 16000 or more, 18000 or more, 19000 or more, or 20000 or more, 450000 or less, 400000 or less, 350000 or less, 300000 or less, 250000 or less, 200000 or less, 150000 or less, 100000 or less, 90000 or less, 80000 or less, 70000 or less, 60000 or less, 50000 or less, 40000 or less, 30000 or less, or 25000 or less.

Examples of the polymer compound that can be used as the secondary surface treatment agent include a polyurethane-based surface treatment agent, a polyurea-based surface treatment agent, a poly(urethane-urea)-based surface treatment agent, and/or a polyester-based (specifically branched polyester-based) surface treatment agent. can be the best As the secondary surface treatment agent, a compound containing a functional group that interacts with the primary surface treatment agent and/or the magnetic particles may be applied to the above-mentioned high molecular compound, or if it does not contain the functional group, such a functional group A secondary surface treatment can also be performed by introducing and applying to a specific polymer compound.

As the secondary surface treatment agent, a compound having a functional group that interacts with the primary surface treatment agent and/or magnetic particles may be applied, and these functional groups include the aforementioned phosphoric acid group, carboxyl group, sulfonic acid group, amino group and/or cyano group. No group, etc., secondary or tertiary amine value or amino group, urea bond, etc. may be exemplified, but are not limited thereto.

In one example, as the secondary surface treatment agent, a polymer including a urea unit and/or a urethane unit may be applied.

In the above, the urea unit may be represented by the following formula (D), and the urea unit may be represented by the following formula (E):

[Formula D]

In Formula D, R ₄ to R ₇ are each independently a hydrogen atom or an alkyl group, and L ₁ and L ₂ are each independently an aliphatic, alicyclic or aromatic divalent residue.

[Formula E]

In Formula E, R ₈ and R ₉ are each independently a hydrogen atom or an alkyl group, and L ₃ and L ₄ are each independently an aliphatic, alicyclic or aromatic divalent residue.

The unit of formula D is a so-called urea unit, and may be a reaction product of a polyamine and a diisocyanate compound. Thus, for example, in Formula D, L ₁ may be a structure derived from a diisocyanate compound participating in the reaction, and L ₂ may be a structure derived from a polyamine participating in the reaction. In the above, the “derived structure” may be a structure excluding an isocyanate group from the diisocyanate compound in the case of _{L 1 , and in the case of L 2} , a structure of a portion excluding an amine group (-NH _{2 ) from the polyamine compound.}

The unit of formula E is a so-called urethane unit, and may be a reaction product of a polyol and a diisocyanate compound. Thus, for example, in Formula E, L ₃ may be a structure derived from a diisocyanate compound participating in the reaction, and L ₄ may be a structure derived from a polyol participating in the reaction. In the above, the “derived structure” may be a structure excluding an isocyanate group from the diisocyanate compound in the case of _{L 3} , and may be a structure of a portion excluding a hydroxyl group (-OH) from the polyol in the case of _{L 4 .}

Examples of the diisocyanate compound capable of forming the structures of Formulas D and E include tolylene diisocyanate, xylene (xylene) diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoborone diisocyanate, and tetramethylxylene. Diisocyanate or naphthalene diisocyanate may be exemplified, but is not limited thereto.

In addition, the polyamine capable of forming the structure of Formula D includes an alkylenediamine having an alkylene unit having 1 to 20, 1 to 16, 1 to 12, 1 to 8, or 1 to 4 carbon atoms, such as ethylenediamine or propylenediamine. This may be exemplified, but not limited thereto.

Further, as the polyol capable of forming the structure of Formula E, alkylene glycol having an alkylene unit having 1 to 20, 1 to 16, 1 to 12, 1 to 8, or 1 to 4 carbon atoms, such as ethylene glycol or propylene glycol. This may be exemplified, but not limited thereto.

Therefore, polyurethane and/or polyurea or poly(urethane-urea) prepared by appropriately combining the above known monomers may be applied as the secondary surface treatment agent. If necessary, it may be applied after introducing a functional group required for the polyurethane and/or polyurea or poly(urethane-urea), etc. by a known chemical method.

As the secondary surface treatment agent, a compound having an appropriate acid value and/or amine value or not having an appropriate acid value and/or amine value may be applied depending on the type of compound mixed with the magnetic material. In one example, the secondary surface treatment agent may have an acid value in the range of 10 mgKOH/g to 400 mgKOH/g, or an amine value in the range of 5 mgKOH/g to 400 mgKOH/g.

In another example, the acid value of the surface treatment agent is about 20 mgKOH/g or more, 30 mgKOH/g or more, 40 mgKOH/g or more, 50 mgKOH/g or more, 60 mgKOH/g or more, 70 mgKOH/g or more, 80 mgKOH/g or more, or 90 mgKOH/g or more. or more, or about 390 mgKOH/g or less, 380 mgKOH/g or less, 370 mgKOH/g or less, 360 mgKOH/g or less, 350 mgKOH/g or less, 340 mgKOH/g or less, 330 mgKOH/g or less, 320 mgKOH/g or less, 310 mgKOH/g or less, 300 mgKOH or less /g or less, 290 mgKOH/g or less, 280 mgKOH/g or less, 270 mgKOH/g or less, 260 mgKOH/g or less, 250 mgKOH/g or less, 240 mgKOH/g or less, 230 mgKOH/g or less, 220 mgKOH/g or less, 210 mgKOH/g or less, 200 mgKOH or less /g or less, 190 mgKOH/g or less, 180 mgKOH/g or less, 170 mgKOH/g or less, 160 mgKOH/g or less, 150 mgKOH/g or less, 140 mgKOH/g or less, 130 mgKOH/g or less, 120 mgKOH/g or less, 110 mgKOH/g or less, or 100 mgKOH/g or less, 90 mgKOH/g or less, 80 mgKOH/g or less, 70 mgKOH/g or less, 60 mgKOH/g or less, 50 mgKOH/g or less, 40 mgKOH/g or less, or 30 mgKOH/g or less .

In another example, the amine value of the surface treatment agent is about 10 mgKOH/g or more, about 15 mgKOH/g or more, about 20 mgKOH/g or more, 30 mgKOH/g or more, 40 mgKOH/g or more, 50 mgKOH/g or more, 60 mgKOH/g or more, 70 mgKOH /g or more, 80 mgKOH/g or more, or 90 mgKOH/g or more, or about 390 mgKOH/g or less, 380 mgKOH/g or less, 370 mgKOH/g or less, 360 mgKOH/g or less, 350 mgKOH/g or less, 340 mgKOH/g or less, 330 mgKOH/g or less g or less, 320 mgKOH/g or less, 310 mgKOH/g or less, 300 mgKOH/g or less, 290 mgKOH/g or less, 280 mgKOH/g or less, 270 mgKOH/g or less, 260 mgKOH/g or less, 250 mgKOH/g or less, 240 mgKOH/g or less, 230 mgKOH/g or less g or less, 220 mgKOH/g or less, 210 mgKOH/g or less, 200 mgKOH/g or less, 190 mgKOH/g or less, 180 mgKOH/g or less, 170 mgKOH/g or less, 160 mgKOH/g or less, 150 mgKOH/g or less, 140 mgKOH/g or less, 130 mgKOH/g or less g or less, 120 mgKOH/g or less, 110 mgKOH/g or less or 100 mgKOH/g or less, 90 mgKOH/g or less, 80 mgKOH/g or less, 70 mgKOH/g or less, 60 mgKOH/g or less, 50 mgKOH/g or less, It may be on the order of 40 mgKOH/g or less or 30 mgKOH/g or less.

In another example, the secondary surface treatment agent may be a compound without an acid value and/or an amine value. In the present application, the absence of an acid value or an amine value means that the acid value or amine value is about 5 mgKOH/g or less, 4 mgKOH/g or less, 3 mgKOH/g or less, 2 mgKOH/g or less, 1 mgKOH/g or less, or 0.5 mgKOH/g or less, or , means a case of substantially 0 mgKOH/g. As described above, the surface treatment agent without an acid value and/or an amine value may be effective when the magnetic material is blended with an epoxy resin or the like.

As the secondary surface treatment agent, a branched polyester surface treatment agent known as a so-called branched polyester-based dispersant may also be applied.

The secondary surface treatment agent may be included in the magnetic body in an amount of 0.01 parts by weight to 30 parts by weight based on 100 parts by weight of the magnetic particles. It is also possible to form a magnetic body having a desired performance under such a ratio. In another example, the ratio is about 0.5 parts by weight or more, 1 part by weight or more, 1.5 parts by weight or more, 2 parts by weight or more, 2.5 parts by weight or more, 3 parts by weight or more, 3.5 parts by weight or more, 4 parts by weight or more, 4.5 parts by weight or more. or more, or 5 parts by weight or more, or about 25 parts by weight or less, 20 parts by weight or less, 15 parts by weight or less, about 13 parts by weight or less, about 12 parts by weight or less, or 10 parts by weight or less.

A method of surface-treating the magnetic particles with the secondary surface treatment agent is not particularly limited. For example, the magnetic body may be manufactured by mixing the magnetic particles (or magnetic particles treated with the primary surface treatment agent) and the secondary surface treatment agent in an appropriate environment such as the presence of a solvent.

The magnetic powder contains at least the magnetic material as described above. In addition, the magnetic powder may include a plurality of the magnetic material. A magnetic powder including such a magnetic material may have specific magnetic properties. Such a magnetic powder can exhibit excellent heating efficiency when a certain magnetic field is applied, and the excellent heating efficiency can be maintained uniformly, and as a result, a cured body having improved cured physical properties, for example, improved dielectric breakdown strength, is formed. can

In one example, the magnetic powder may have a coefficient of variation of a particle diameter of magnetic particles in the magnetic powder, specifically, in the magnetic body within a specific range. Specifically, in the magnetic powder, the coefficient of variation of the particle size of the magnetic particles in the magnetic body included in the powder may be in the range of 5% to 30%. In the above, the coefficient of variation of a factor may mean a ratio of the standard deviation of the factor to the mean of the factor expressed as a percentage. That is, in the magnetic powder, the ratio of the standard deviation of the particle diameter of the magnetic particle to the average of the particle diameter of the magnetic particle may be in the range of 5% to 30%. The coefficient of variation may be estimated through electron micrographs obtained with respect to the magnetic powder.

In one example, the magnetic powder may have a specific saturation magnetization value. Specifically, the saturation magnetization value of the magnetic powder may be in the range of 20 emu/g to 150 emu/g. When an electromagnetic field is applied to the magnetic powder when the saturation magnetization value of the magnetic powder is within the above range, heat may be generated by vibration between the magnetic material, specifically, the magnetic particles included in the magnetic material, rather than the eddy current of the magnetic powder. and, as a result, a high amount of heat can be uniformly generated.

In one example, the magnetic powder may have a coercive force within a specific range. Specifically, the coercive force of the magnetic powder may be in the range of 1 kOe to 200 kOe. In the above, the term “coercive force” may mean the strength of a critical magnetic field required to reduce the magnetization of a magnetic material (or magnetic powder) to zero. That is, a magnetic material or magnetic powder magnetized by an external magnetic field forms a magnetized state to a certain extent even if the magnetic field is removed. is called the coercive force. The coercive force may be a criterion for classifying a soft magnetic material or a hard magnetic material, and the magnetic powder applied to the cured body of the present application may be, for example, a soft magnetic powder. In the present application, by adjusting the coercive force of the magnetic powder within the above range, magnetic conversion of the magnetic body in the magnetic powder can be more easily implemented, and as a result, vibrational heat of the desired degree in the present application can be generated.

In the present application, the physical properties of the magnetic powder may be measured using a Vibrating Sample Magnetometer (VSM). VSM records the magnetic field applied by the Hall probe, and the magnetization value of the sample is a device that measures the magnetization value of the sample by recording the electromotive force obtained when vibration is applied to the sample according to Faraday's law. According to Faraday's law, if the N pole of a bar magnet is directed toward the coil and pushed toward the coil, the galvanometer moves and current flows through the coil. The resulting current is called induced current and is said to be created by induced electromotive force. VSM is a method of measuring the magnetization value of the sample by detecting the induced electromotive force generated when vibration is applied to the sample by the search coil according to this basic operating principle. Magnetic properties of materials can be measured simply as a function of magnetic field, temperature, and time, and magnetic force of up to 2 Tesla and rapid measurement in the temperature range of 2 K to 1273 K are possible.

The magnetic powder included in the curable composition of the present application may also have a specific specific surface area. Specifically, the magnetic powder may have a BET specific surface area in the range of 3 m ² /g to 25 m ² /g.

In the present application, the BET specific surface area may be the specific surface area of the magnetic particles measured according to the Brunauer-Emmett-Teller equation (BET) adsorption isothermal equation, specifically, the adsorption isothermal equation introduced as a model for multi-molecular layer adsorption, and the BET equation Methods for measuring the specific surface area through the parameters of and the BET equation are variously known in the art. The size of the pores formed by the magnetic particles in the magnetic material constituting the magnetic powder can be known through the BET specific surface area, and the size of the magnetic particles and the particle size distribution thereof can be confirmed through this.

The magnetic powder may also have excellent exothermic properties. For example, the magnetic powder may have an SAR value of 60 W/g or more calculated according to Equation 2:

[Formula 2]

SAR = Ci×m×ΔT/Δt

In Equation 2, SAR means the calorific value of the magnetic fluid obtained by dissolving the magnetic powder in water, Ci is the specific heat of water, which is the solvent of the magnetic fluid, 4.184 J/(g×K), and m is the amount of heat of the magnetic fluid _{The ratio (m i} /m _A ) of the weight (m _i , unit: g) of the solvent water (m i , unit: g) and the weight (m _A , unit: g) of the magnetic powder, ΔT is 0.35 mL of the magnetic fluid at a temperature of 294 K is the amount of temperature increase (unit: K) of the magnetic fluid when an alternating magnetic field is applied for 60 seconds under the conditions of a current of 120.4 A and a frequency of 310 kHz, and Δt is the time when the alternating magnetic field under the conditions is applied to the magnetic fluid is 60 seconds.

The SAR value is a standardized heat generated by the magnetic powder when an alternating magnetic field of a specific intensity is applied to a specific amount of magnetic powder, and the value must be at least 60 W/g to achieve the desired heating characteristic in the present application. It is understood that it can be implemented. The SAR value may be, in another example, 63 W/g or more, 65 W/g or more, 67 W/g or more, or 70 W/g or more, 120 W/g or less, 115 W/g or less, or 110 W/g may be below. In particular, the upper limit of the SAR value may vary depending on the type of solvent applied to measure the value. In addition, in the present application, water was applied as a solvent to measure the SAR value, and the upper limit of the numerical value (120 W/g) means the maximum SAR value that can appear when the solvent applied to measure the value is water. can do.

In one example, the hardening body may be an insulating hardening body. In the present application, the term “insulation” refers to a dielectric breakdown strength of 10 kV/mm or more, 11 kV/mm or more, 12 kV/mm or more, 13 kV/mm or more, 14 kV/mm or more, 15 kV as determined by ASTM D149 standard. /mm or more, 16 kV/mm or more, 17 kV/mm or more, 18 kV/mm or more, 19 kV/mm or more, or 20 kV/mm or more. The higher the dielectric breakdown strength, the better the insulation, and the upper limit is not particularly limited, but in one example, about 50 kV / mm or less, 45 kV / mm or less, 40 kV / mm or less, 35 kV/mm or less, 30 kV/mm or less, 25 kV/mm or less, or 20 kV/mm or less. The dielectric breakdown strength is a value measured according to ASTM D149 standard for the film-type cured body when the cured body is in the form of a film, and unless otherwise specified, the unit is kV/mm.

The dielectric breakdown strength may be achieved by adjusting the type and/or ratio of the cured resin and/or magnetic powder constituting the cured body, for example, may be achieved by applying a component of the type to be described later.

The kind of curable resin that may be included in the cured body is not particularly limited. For example, as the curable resin, a so-called “thermosetting resin” that participates in a curing reaction by application of heat may be applied. In addition, as the curable resin, a so-called insulating resin, a resin capable of exhibiting the above-described insulating properties (insulation breaking strength) before and/or after curing may be applied.

Such a curable resin may contain a curable functional group. Specifically, as the curable functional group, an alkenyl group, an acryloyl group, a methacryloyl group, an acryloyloxy group, a methacryloyloxy group, an acryloyloxyalkyl group, a methacryloyloxyalkyl group, an epoxy group, an oxetane group, an alke group A nyl group, a hydrogen atom bonded to a silicon atom, an isocyanate group, a hydroxyl group, a phthalonitrile group or a carboxyl group may be exemplified, but the present invention is not limited thereto.

In the present application, the term “alkenyl group” refers to an alkenyl group having 2 to 20, 2 to 16, 2 to 12, 2 to 8, or 2 to 4 carbon atoms, unless otherwise specified. The alkenyl group may be linear, branched or cyclic, and may be optionally substituted with one or more substituents.

In the present application, unless otherwise specified, the term "epoxy group" may refer to a cyclic ether having three ring atoms or a monovalent residue derived from a compound including the cyclic ether. Examples of the epoxy group include a glycidyl group, an epoxyalkyl group, a glycidoxyalkyl group, or an alicyclic epoxy group. In the above, the alicyclic epoxy group may mean a monovalent residue derived from a compound containing an aliphatic hydrocarbon ring structure, and a structure in which two carbon atoms forming the aliphatic hydrocarbon ring also form an epoxy group. As the alicyclic epoxy group, an alicyclic epoxy group having 6 to 12 carbon atoms can be exemplified, and for example, a 3,4-epoxycyclohexylethyl group and the like can be exemplified.

A specific kind of the curable resin is not particularly limited. For example, the curable resin may be a resin having a linear or branched structure including the aforementioned curable functional group, and specifically, polysilicon resin, polyimide, polyetherimide, polyesterimide, acrylic resin , vinyl-based resins, olefin resins, polyurethane resins, isocyanate resins, acrylic resins, polyester resins, phthalonitrile resins, polyamic acids, polyamides or epoxy resins may be exemplified.

The ratio of the magnetic powder in the cured body of the present application is not particularly limited. The ratio of the magnetic powder may be appropriately adjusted in consideration of heat required to form the corresponding cured body. In one example, the cured body may include the magnetic powder in an amount of 0.01 to 60 parts by weight based on 100 parts by weight of the cured resin. In another example, the proportion of the magnetic powder is about 0.5 parts by weight or more, or about 1 part by weight or more, about 3 parts by weight or more, or about 5 parts by weight or more, or about 55 parts by weight or less, about 50 parts by weight or less, about 45 parts by weight or less. parts by weight or less, about 40 parts by weight or less, about 35 parts by weight or less, about 30 parts by weight or less, about 25 parts by weight or less, about 20 parts by weight or less, about 15 parts by weight or less, or about 10 parts by weight or less. Curable resin, which is a criterion in calculating the ratio of the magnetic powder, is a component that is in a resin state, of course, is not in a resin state, but a curable resin before forming a cured body after starting the curing, that is, a resin that can form a resin by curing ingredients are also included.

The cured body may further include any additives required for the cured body in addition to the above-described components. Examples of such additives include a curing agent that aids in curing the curable resin, a catalyst or initiator such as a radical or cationic initiator, a thixotropic agent, a leveling agent, an antifoaming agent, an antioxidant, a radical generating substance, an organic/inorganic pigment to dyes, dispersants, various fillers such as thermally conductive fillers or insulating fillers, functional polymers or light stabilizers, and the like may be exemplified.

The method of manufacturing the magnetic powder (or magnetic body) applied to the hardening body is not particularly limited, but in the present application, the magnetic body can be prepared through a specific method, and the magnetic powder can be prepared by appropriately mixing the magnetic material. have. In addition, the cured body of the present application may be manufactured through a method to be described later.

On the other hand, if the magnetic material is prepared in a specific manner, the magnetic material and magnetic powder exhibiting the above-described characteristics can be obtained in a higher yield and in a more convenient manner.

The method for manufacturing the magnetic material includes: a first step of generating a crystal (or magnetic domain) of magnetic particles using a specific raw material; a second step of clustering the crystals generated in the first step; and a third step of mixing the raw material having the clustered crystals with a surface treatment agent.

Specifically, the method may include a first step of generating crystals by heating a raw material including a precursor of magnetic particles and a polar solvent. In the method, when a raw material including at least a magnetic particle precursor and a polar solvent is heated, crystals constituting the magnetic particles may be formed.

In the above, the magnetic particle precursor may mean a material capable of forming magnetic particles through a specific reaction. The reaction of the magnetic particle precursor into the magnetic particle proceeds through heating of a raw material including at least a precursor of the magnetic particle and a polar solvent.

The description of the magnetic particles is the same as described above, and the precursor of the magnetic particles is not particularly limited as long as it is a compound capable of forming the magnetic particles through hydrolysis, dehydration, reduction, and phase change of the precursor. For example, when the magnetic particle is FeOFe ₂ O ₃ , the precursor of the magnetic particle is FeCl ₃ , Fe(NO ₃ ) ₃ , Fe(CO) ₅ , Fe(NO ₃ ) ₂ , Fe(SO ₄ ) ₃ or Fe(AcAc) ₃ {iron (III) acetylacetonate}, but is not limited thereto.

The ratio of the magnetic particle precursor is also not particularly limited. In one example, the raw material may include the magnetic particle precursor in a ratio within the range of 0.025 M to 0.125 M. The ratio of the magnetic particle precursor may be, in another example, 0.03 M or more, 0.04 M or more, or 0.05 M or more, and may be 0.120 M or less, 0.115 M or less, or 0.1 M or less.

As the polar solvent, any known polar solvent may be applied without limitation, as long as it can properly dissolve the precursor of the magnetic particles. Specifically, since the polar solvent may act as a reducing agent for the magnetic particle precursor, the polar solvent may also be referred to as a “reducing polar solvent” in some cases. In the above, the term “polar” may refer to a solvent having a dielectric constant at a specific temperature, for example, 25° C., in the range of about 75 to about 85. In particular, in order to uniformly dissolve the precursor of the magnetic particles in the raw material, and to apply as a reducing agent for the phase transition reaction of the magnetic particle precursor to the magnetic particles, specifically, the reduction reaction of the magnetic particle precursor, the polar solvent is It may be suitable to apply a polyol. In the above, the polyol may refer to a compound having two or more hydroxyl groups (-OH) as in the known meaning. Accordingly, the raw material may include a precursor of the magnetic particles and a polyol.

Examples of the polyol applied to the raw material include so-called low molecular weight polyols such as ethylene glycol, glycerine, butanediol, and trimethylol propane; and high molecular weight polyols such as polyethylene glycol and methoxypolyethylene glycol, but is not limited thereto. In the above, the low molecular weight polyol may mean a monomolecular polyol, and the high molecular weight polyol may mean a polyol having a molecular weight (weight average molecular weight) of 2,000 or less among high molecular weight polyols.

In one example, the raw material may include the polar solvent, for example, a polyol as a main component. In the above, that the raw material contains the polar solvent as a main component means that the ratio of the polar solvent in the raw material is 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, based on weight. , 75% or more, 80% or more, 85% or more, or 90% or more, and about 100%, 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less.

The method for manufacturing the magnetic material includes a second step of clustering the crystals generated in the first step. As used herein, the term clustering may refer to a phenomenon in which the crystals or magnetic domains are densely aggregated (or aggregated) to form one particle unit. In the method for manufacturing the magnetic material, at least crystals may be formed using a magnetic particle precursor in the first step, and at least magnetic particles may be formed by clustering the crystals thus formed in the second step. A method of clustering the crystals is not particularly limited. For example, by heat-treating (or heating) the result of the first step, that is, the raw material in which the crystals are formed at a predetermined temperature, clustering of the crystals may proceed. The specific process of the second step will be described later.

In the method of manufacturing the magnetic material, the raw material that has undergone both the first and second steps is mixed with a surface treatment agent. As for the description of the surface treatment agent, the above-described content is applicable as it is. As described above, when the raw material that has undergone both the first and second steps is mixed with a surface treatment agent at least, magnetic particles having a plurality of magnetic domains of a specific size, multi-domain type, and having an average particle diameter within a specific range, A magnetic body including a surface treatment agent introduced to the surface of the magnetic particles may be formed.

Even if the raw material is not mixed with the surface treatment agent or the surface treatment agent is mixed with the raw material, the time point is before the second step, specifically, the surface treatment agent is mixed with the raw material in the first step, or produced in the first step When the surface treatment agent is mixed with the raw material in the process of clustering the crystals, the magnetic material having the above characteristics is not manufactured. Specifically, the thus-prepared magnetic material has a form in which the surface treatment agent is introduced into the surface of the crystal constituting the magnetic particle, not the surface of the magnetic particle. The magnetic material manufactured in this way does not exhibit the heating characteristics desired in the present application, for example, a high heating value when a certain electromagnetic field is applied, and a characteristic in which the heating value is uniformly maintained.

On the other hand, in the method for producing the magnetic body, the magnetic body having the above-described particle characteristics can be manufactured by specifically specifying the time point at which the surface treatment agent is mixed. Accordingly, as in the third step, if the crystals formed through the precursor of magnetic particles are clustered and then mixed with a surface treatment agent, a magnetic material more effective for curing the curable composition may be formed.

In the method for manufacturing the magnetic material, in the first step, at least a phase transition reaction of the magnetic particle precursor to the magnetic particle, specifically, a reduction reaction in which the oxidation number of the metal component of the magnetic particle precursor is reduced. Specifically, since the reaction to the magnetic particles proceeds through hydrolysis, dehydration, and reduction processes of the magnetic particle precursor, the raw material applied in the first step contains additional substances in addition to the magnetic particle precursor and the polar solvent. may be included.

Specifically, since hydrolysis of the magnetic particles may proceed in the first step, the reaction in which the magnetic particle precursor forms crystals may proceed in the presence of at least an aqueous solvent. Accordingly, the raw material may further include an aqueous solvent. As the aqueous solvent in the above, water or other polar solvents may be applied, and water may be typically applied. The proportion of the aqueous solvent is not particularly limited. For example, the raw material may include the aqueous solvent in a ratio within the range of 1% by volume to 30% by volume relative to the volume of the polar solvent. The proportion of the aqueous solvent may be, in another example, 2% by volume or more, 3% by volume or more, 4% by volume or more, or 5% by volume or more, and 25% by volume or less, 20% by volume or less, or 15% by volume or less.

The phase transition of the magnetic particle precursor to the magnetic particle, specifically, the reduction reaction of the magnetic particle precursor to the magnetic particle, may proceed through a reaction between the precursor of the magnetic particle and a base. Accordingly, the raw material may further include a base (a basic compound) in the precursor of the magnetic particles, the polar solvent, and the aqueous solvent.

The kind of the base (basic compound) applied to the raw material for producing the magnetic particles is not particularly limited. As a compound applied as a basic compound in the present application, a compound known in the industry as basic, that is, ^{a compound capable of emitting hydroxide ions (-OH) or absorbing hydrogen ions (H +} ) in aqueous solution, or a compound having a pH of 7 or higher can be applied without limitation. For example, examples of the base that can be applied to the raw material include strong basic compounds such as sodium hydroxide and potassium hydroxide; Alternatively, a weak basic compound such as sodium carbonate, sodium hydrogen carbonate, cesium carbonate, calcium carbonate, aqueous ammonia or sodium acetate may be applied, and in the examples of the present application, sodium acetate was applied as the base.

The ratio of the base in the raw material is not particularly limited. The raw material may include a base in a ratio within the range of 0.4 M to 2.0 M. The ratio of the base in the raw material, in another example, may be 0.5 M or more, 0.6 M or more, or 0.7 M or more, and 1.9 M or less, 1.8 M or less, 1.7 M or less, 1.6 M or less, 1.5 M or less, 1.4 M or less or less, 1.3 M or less, 1.2 M or less, or 1.1 M or less.

Each of the first to third steps, which are represented by each of the above processes involved in the method for producing the magnetic material, specifically, a process of forming a crystal, a process of clustering a crystal, and a process of surface treatment of magnetic particles, is performed at a temperature within a specific range. It can proceed for a certain range of time.

In one example, the first step may be performed at a temperature within the range of 50 °C to 90 °C. That is, the first step may be performed while heating the raw material at a temperature within the range. Crystals constituting the magnetic particles may be appropriately formed within the temperature range. The temperature condition of the first step, in another example, may be 55 ℃ or more, 60 ℃ or more, 65 ℃ or more, or 70 ℃ or more, 85 ℃ or less, 80 ℃ or less, 75 ℃ or less, or 70 ℃ or less.

Also, the first step may be performed at a temperature within the above-described range for a specific time. Specifically, at a temperature within the above-described range, the first step may be performed for a time within the range of 1 minute to 3 hours. By performing a process of forming crystals, specifically, crystals of magnetic particles for a period of time within the above range, magnetic particles having a magnetic domain having the above-described size characteristics may be formed. In another example, the time may be 5 minutes or more, 10 minutes or more, 15 minutes or more, or 20 minutes or more, and may be 2 hours or less, 1 hour or less, 30 minutes or less, 25 minutes or less, or 20 minutes or less.

In one example, the second step, specifically, the step of clustering the crystals generated in the first step may also proceed at a temperature within a specific range. Specifically, the second step may be performed at a temperature within the range of 170 °C to 210 °C. In the above temperature range, magnetic particles having the above size and having a multi-domain type may be appropriately formed. The temperature condition of the second step, in another example, may be 175°C or more, 180°C or more, 185°C or more, or 190°C or more, and 205°C or less, 200°C or less, 195°C or less, or 190°C or less.

In addition, as in the second step and the first step, the temperature may be performed for a specific time while meeting within the above range. Since the average size of the magnetic particles in the magnetic body may be determined according to the time for clustering the crystals generated in the first step, the second step also needs to be performed for a time within an appropriate range. For example, the second step may be performed for a time within the range of 30 minutes to 72 hours. The duration of the second step may be, in another example, 60 minutes or more, 90 minutes or more, or 120 minutes or more, and 60 hours or less, 48 hours or less, 36 hours or less, 24 hours or less, 12 hours or less, 6 hours or less , 4 hours or less or 2 hours or less.

The third step, specifically, the process of mixing the raw material that has undergone the crystal clustering process with the surface treatment agent may also be appropriately carried out at a temperature within a specific range. In particular, the temperature condition of the third step may also be appropriately adjusted from the viewpoint of smoothly achieving the interaction between the surface treatment agent and the magnetic particles. For example, the third step may be performed at a temperature within the range of 50 °C to 90 °C. The temperature condition of the third step, in another example, may be 55 °C or higher, 60 °C or higher, 65 °C or higher, or 70 °C or higher, and 85 °C or lower, 80 °C or lower, 75 °C or lower, or 70 °C or lower. In particular, as the surface treatment agent, for example, a surface treatment agent in powder form may be applied, and the surface treatment agent may be dissolved in a solvent such as water and applied in the form of a solution. In the third step, the progress temperature can be controlled within the above-described range from the standpoint of securing the .

The third step may also be carried out for an appropriate time under the temperature conditions in the above range from the viewpoint of ensuring an appropriate interaction between the surface treatment agent and the magnetic particles and preparing a magnetic material having magnetic particles having a desired average particle diameter. For example, the third step may be performed for a time within the range of 30 minutes to 4 hours. The duration of the third step may be, in another example, 40 minutes or more, 50 minutes or more, 60 minutes or more, 70 minutes or more, 80 minutes or more, 90 minutes or more, 100 minutes or more, 110 minutes or more, or 120 minutes or more. , 210 minutes or less, 180 minutes or less, 150 minutes or less, or 120 minutes or less.

In addition, in the manufacturing method of the magnetic body, in the third step, the raw material that has passed the second step is treated for a time within the range so that the raw material has a temperature within the range, and then the treated raw material is mixed with the above-mentioned surface treatment agent can do.

In the method for manufacturing the magnetic body, in particular, by controlling the treatment conditions of the surface treatment agent mixed in the third step, a magnetic body having a desired size characteristic can be manufactured.

As the surface treatment agent applied in the method, the surface treatment agent mentioned in the description of the above-described magnetic material may be applied as it is.

In one example, the ratio of the surface treatment agent mixed in the third step may also be appropriately adjusted. Specifically, in the method of the present application, in the third step, the surface treatment agent may be mixed in a ratio within the range of 0.01 parts by weight to 30 parts by weight based on 100 parts by weight of the magnetic particle precursor. The proportion of the surface treating agent may be, in another example, 0.1 parts by weight or more, 1 part by weight or more, 2 parts by weight or more, 3 parts by weight or more, or 4 parts by weight or more, and 27 parts by weight or less, 25 parts by weight or less, 23 parts by weight or less. parts by weight or less, 21 parts by weight or less, or 20 parts by weight or less. On the other hand, in the method of the present application, the surface treatment agent is added after the magnetic crystals are clustered, and since the surface treatment agent does not significantly affect the average particle diameter of the previously formed magnetic particles, the ratio of the surface treatment agent is beyond the appropriate range. Specifically, even if the ratio exceeds the above range, physical properties such as the size of the magnetic particles may not be affected.

The magnetic material may include an additional surface treatment agent, for example, the secondary surface treatment agent described above. Accordingly, the method may further include a process of secondary surface treatment with the secondary surface treatment agent. As the secondary surface treatment agent, the second surface treatment agent mentioned in the description of the magnetic material may be applied as it is.

Specifically, the third step is a step (a) of mixing the raw material that has undergone the second step with the above-described surface treatment agent and mixing with a secondary surface treatment agent that can be combined with the surface treatment agent following step (a) (b) may be included. For example, in the method of the present application, the above-mentioned surface treatment agent is mixed with the raw material that has undergone the second step in the third step, and then a secondary surface treatment agent is added, and when reacted for an appropriate time, the second surface treatment agent is added A surface-treated magnetic body may be manufactured.

In addition, the mixing ratio of the secondary surface treatment agent is also not particularly limited. For example, in step (b), the raw material that has undergone step (a) may be mixed with a secondary surface treatment agent in the range of 0.01 parts by weight to 30 parts by weight based on 100 parts by weight of the magnetic particles. The ratio of the secondary surface treatment agent is, in another example, about 0.5 parts by weight or more, 1 part by weight or more, 1.5 parts by weight or more, 2 parts by weight or more, 2.5 parts by weight or more, 3 parts by weight or more, 3.5 parts by weight or more, 4 parts by weight or more. parts by weight or more, 4.5 parts by weight or more, or 5 parts by weight or more, or about 25 parts by weight or less, 20 parts by weight or less, 15 parts by weight or less, about 13 parts by weight or less, about 12 parts by weight or less, or 10 parts by weight or less.

According to the above-described method, it may have excellent exothermic properties, and thus a magnetic body particularly suitable for manufacturing the cured body of the present application may be manufactured.

The present application also relates to a method for producing a cured body. The method of the present application includes at least the step of curing the curable composition by induction heating the curable composition. Specifically, the method of the present application includes at least the step of curing the curable composition by applying an electromagnetic field to the curable composition.

The curable composition applied in the method of the present application includes at least a curable resin. In the above, the curable resin may mean a polymer that can be cured by external force such as application of heat or irradiation of light. In the method of the present application, the composition is cured by applying an electromagnetic field to the composition. Specifically, the curable resin may be cured by the application of the electromagnetic field. Therefore, the curable resin may be a precursor of the cured resin included in the cured body of the present application described above.

As for the description of the curable resin, the curable resin described in the above-described cured body is applicable as it is.

The curable composition applied in the method of the present application includes at least a heating material capable of generating heat by application of an electromagnetic field. Specifically, in the present application, magnetic powder is applied as the heating material. The magnetic powder is a material exhibiting magnetism as described above, and refers to a material capable of generating heat when an electromagnetic field having a predetermined intensity is applied from the outside. Specifically, the magnetic powder may generate heat by a magnetic reversal vibration phenomenon through an external alternating magnetic field.

As with the curable resin, the description of the magnetic powder is applicable to the magnetic powder described in the above-described cured body as it is. Therefore, the magnetic powder applied in the method of the present application also includes a magnetic material including at least magnetic particles and a surface treatment agent introduced to the surface of the magnetic particles, and the magnetic particles have a size within the range of 10 nm to 40 nm. It is a multi-domain type magnetic particle containing two or more crystals, and the average particle diameter of the magnetic particle is in the range of at least 20 nm to 300 nm.

As described above, in the cured body of the present application, the magnetic body of the magnetic powder is oriented in a specific direction in the magnetic powder applied thereto. In the method of the present application, the direction in which the electromagnetic field is applied is specifically specified so that the magnetic material is oriented in a specific direction as described above. As a result, a cured body including the oriented magnetic body may be formed as described above, and the cured body may have improved cured properties, specifically improved insulation, and more specifically improved dielectric breakdown strength, as described above.

As described above, when the magnetic material in the hardening body is oriented in a direction that can block the movement of electrons in the current applied for the measurement, it may have improved dielectric breakdown strength. In order to block electrons moving in the current applied to measure the dielectric breakdown strength, it is appropriate to be substantially perpendicular to the direction of the applied current. When the magnetic material is oriented in a direction approximately parallel to the direction in which the electrons of the applied current move in order to measure the dielectric breakdown strength, the magnetic material rather acts as a path through which the electrons of the current move, so it helps to improve the dielectric breakdown strength. can't be

On the other hand, the current applied to measure the dielectric breakdown strength is approximately parallel to or approximately perpendicular to the direction of gravity. Accordingly, the magnetic body is also oriented along the above-mentioned direction. That is, in the method of the present application, in the curing of the curable composition, an electromagnetic field is applied so that the magnetic body is oriented in a direction substantially parallel to or substantially perpendicular to a direction parallel to a direction of gravity in the cured resin material. Specifically, in the method of the present application, in the step of curing the curable composition, the electromagnetic field is directed at an angle within a range of -10 degrees to 10 degrees with an axis in a direction parallel to the direction of gravity (in some cases, also called a “first angle”) ) or an angle within the range of 80 degrees to 100 degrees (in some cases, it is also called a “second angle”).

The first angle may be, in another example, -7 degrees or more, -5 degrees or more, -3 degrees or more, or -1 degrees or more, and 7 degrees or less, 5 degrees or less, 3 degrees or less, or 1 degree or less, or It may be on the order of 0 degrees.

In another example, the second angle may be 83 degrees or more, 85 degrees or more, 87 degrees or more, or 89 degrees or more, 97 degrees or less, 95 degrees or less, 93 degrees or less, or 91 degrees or less, or about 90 degrees. can

On the other hand, in most of the dielectric breakdown strength measurement methods, including the methods mentioned in the embodiments to be described later, since the direction of the current applied for the measurement (also referred to as the conduction direction) is parallel to the direction of gravity, conduction as described above In order to increase insulation by blocking the movement of electrons flowing in the direction, it may be appropriate to apply the electromagnetic field at the second angle. That is, in the method of the present application, in the curing step of the curable composition, the electromagnetic field is applied at an angle within the range of 80 degrees to 100 degrees with the axis in a direction parallel to the direction of gravity, specifically 83 degrees or more, 85 degrees or more, 87 degrees or more, or It may be appropriate to apply an angle of greater than or equal to 89 degrees, less than or equal to 97 degrees, less than or equal to 95 degrees, less than or equal to 93 degrees or less than or equal to 91 degrees, or approximately 90 degrees.

In the method of the present application, vibrational heat may be generated in the magnetic powder by applying an electromagnetic field under the above conditions, whereby the composition may be cured.

In addition, in the method of the present application, the curable composition may be coated in a film or sheet form prior to application of the electromagnetic field in the curing step. At this time, the method may apply an electromagnetic field after coating the curable composition to a thickness within the range of 0.1 mm to 10 mm in the curing step. In another example, the coating thickness may be 0.5 mm or more or 1 mm or more, and 5 mm or less, 3 mm or less, or 1 mm or less.

At this time, the conditions for applying the electromagnetic field applied above are not particularly limited because they are determined according to the type, ratio, and characteristics of the curable resin and/or magnetic powder in the curable composition. In addition, the application of the electromagnetic field may be performed while applying the electromagnetic field to the curable composition through an induction heater formed in the form of a coil or the like.

In an example, the method of the present application may apply an electromagnetic field with a magnetic flux density (or strength) within a range of ^{1 mT (mTesla, mWb/m 2 ) to 100 mT in the curing step of the curable composition.} In another example, the magnetic flux density may be 5 mT or more, 10 mT or more, 15 mT or more, 20 mT or more, 25 mT or more, 30 mT or more, 35 mT or more, or 40 mT or more, 90 mT or less, 80 mT or less, 70 mT or less, 60 mT or less, 50 mT or less, 45 mT or less, or 40 mT or less.

The application time of the electromagnetic field is also not particularly limited. On the other hand, since induction heating through application of an electromagnetic field proceeds within a shorter time than the curing method such as hot air drying described above, the time is generally adjusted in units of minutes. In one example, the method of the present application may be applied for a time within the range of 1 minute to 60 minutes in the curing step of the curable composition. In another example, the application time of the electromagnetic field may be 3 minutes or more, 5 minutes or more, 7 minutes or more, 9 minutes or more, or 10 minutes or more, and 50 minutes or less, 40 minutes or less, 30 minutes or less, 20 minutes or less, or 10 minutes may be below.

The curing of the curable composition may be performed only by the above-mentioned induction heating or, if necessary, may be performed while additionally applying appropriate heat together with the induction heating.

The cured body of the present application may have improved curing properties, for example, improved dielectric breakdown strength.

The manufacturing method of the cured body of the present application can rapidly manufacture the cured body having improved curing properties.

1 and 2 are surface optical micrographs of Example 1.
3 and 4 are surface optical micrographs of Comparative Example 1.
5 and 6 are surface optical micrographs of Comparative Example 2.
7 and 8 are surface optical micrographs of Comparative Example 3.

Hereinafter, the present application will be described in detail through examples. However, the scope of the present application is not limited by the following examples.

Measurement of dielectric breakdown strength of hardened body

By cutting the cured body prepared in Examples and Comparative Examples, a specimen having a horizontal and vertical thickness of about 50 mm and a thickness of about 1 mm is prepared.

For the above specimen, the dielectric breakdown voltage is measured according to ASTM D149 standard, and then this is converted into dielectric breakdown strength per unit thickness. The converted value is an average value measured for each specimen by preparing seven specimens.

Preparation Example 1. Preparation of magnetic powder

A magnetic body was prepared according to the following procedure.

(1) A raw material is prepared by mixing a magnetic particle precursor (Iron (III) chloride hexahydrate), an aqueous solvent (distilled water), and a base (sodium acetate) with a polar solvent (ethylene glycol). The concentrations of the magnetic particle precursor and the base in the raw material are approximately 0.05 M and 0.76 M, respectively, and the aqueous solvent is mixed so as to be 5.26% by volume relative to the volume of the polar solvent.

(2) The raw material is heated at room temperature (about 23° C.) until the temperature of the raw material becomes about 70° C. (for a time of about 20 minutes at a temperature increase rate of about 2.5° C./min) to form crystals.

(3) Heat the raw material that has undergone the step (2) until the temperature reaches approximately 190°C (for a time of about 120 minutes at a temperature increase rate of about 1°C/min) to obtain the crystals generated in the step (2) cluster it.

(4) Cool until the temperature of the raw material that has undergone the step (3) becomes approximately 70 ° C (for a time of about 120 minutes at a temperature reduction rate of about 1 ° C/min), and a surface treatment agent (weight Polyacrylic acid having an average molecular weight of about 5,100 (Sigma Aldrich) is mixed at room temperature (about 23° C.) in an amount of about 19.44 parts by weight based on 100 parts by weight of the magnetic particle precursor applied to the raw material.

Example 1. Cured body

curable composition

As a thermosetting resin, a liquid epoxy resin (a mixture of Kukdo Chemical's KSR-177 and AKEMA's EH4357 in a weight ratio of 97:3) and the magnetic powder of Preparation Example 1 were mixed in a weight ratio of 95:5 to prepare a curable composition. prepared.

hardening body

The curable composition was injected into a Teflon mold substrate (a substrate having a size of 50 mm in width, 50 mm in length and 1 mm in thickness), and a known electromagnetic field applying device was applied in a direction approximately perpendicular to the direction of gravity (direction parallel to the ground). Using an alternating magnetic field of 40 mT intensity was applied for about 10 minutes to form a cured body having a size of 50 mm in width, 50 mm in length, and 1 mm in thickness. 1 (visible light) and FIG. 2 (ultraviolet light) are surface optical micrographs of the cured body of Example 1, since the magnetic particles are oriented perpendicular to the direction of gravity, when viewed from the surface, the magnetic particles are approximately in the form of lines. Confirmed.

Comparative Example 1. Cured body

A cured product was prepared in the same manner as in Example 1, except that an electromagnetic field was applied in a direction approximately parallel to the direction of gravity during curing of the curable composition. 3 (visible light) and 4 (ultraviolet light) are surface optical micrographs of the cured body of Comparative Example 1, since the magnetic particles are oriented parallel to the direction of gravity, when viewed from the surface, the magnetic particles are in a certain area (or point) is confirmed.

Comparative Example 2. Cured body

When the curable composition is cured without applying a magnetic powder to the curable composition, heating at a temperature of 120 degrees for a time of 60 minutes using a known oven, and then heating at a temperature of 150 degrees for a time of 120 minutes, except that A cured body was prepared in the same manner as in Example 1. 5 (visible light) and 6 (ultraviolet light) are surface optical micrographs of the cured body of Comparative Example 2, and since magnetic powder was applied, no area corresponding to the magnetic powder was observed no matter what wavelength was taken as a reference.

Comparative Example 3. Cured body

A cured product was prepared in the same manner as in Example 1, except that, when curing the curable composition, it was heated at a temperature of 120°C for a time of 60 minutes using a known oven and then heated at a temperature of 150°C for a time of 120 minutes. did. 7 (visible light) and 8 (ultraviolet light) are surface optical micrographs of the cured body of Comparative Example 2, magnetic powder was applied, but an electromagnetic field was not applied in a specific direction, so an area corresponding to randomly dispersed magnetic powder This was observed.

The results of evaluation of physical properties of the cured products of Examples and Comparative Examples are shown in Table 1 below.

As shown in Table 1, Comparative Example 2 of a cured body prepared through oven curing without applying magnetic powder had the most excellent insulation, but since it takes a considerable amount of time (about 3 hours) to prepare it, the present application It can be seen that it is not suitable for the purpose of On the other hand, in the case of Comparative Example 3 relating to the cured body manufactured through oven curing even if the magnetic powder is mixed, the insulation is not excellent compared to the Example, and it is not suitable for the purpose of the present application because it takes a considerable time to manufacture it. have.

In addition, even when the curable resin and magnetic powder are mixed, it can be seen that the cured body of Comparative Example 1 in which the orientation of the magnetic material is approximately parallel to the current direction for measuring the dielectric breakdown strength of the cured body has the lowest dielectric breakdown strength, which is It is expected that it is due to the action of the electron movement path of the applied current in the process of measuring the dielectric breakdown voltage of the hardening body.

On the other hand, the hardening body of Example 1, in which the orientation of the magnetic body is substantially perpendicular to the current direction for measuring the dielectric breakdown strength of the hardening body, has a high dielectric breakdown strength of about 90% compared to Comparative Example 2, and at the same time the manufacturing time Also, since it is short, it can be seen that it is suitable for the purpose of the present application.

Claims (21)

Containing a cured resin and magnetic powder present in the cured resin,
The magnetic powder includes magnetic particles and a magnetic body including a surface treatment agent introduced to the surface of the magnetic particles,
The magnetic particles are multi-domain magnetic particles including two or more crystals having a size in the range of 10 nm to 40 nm, and have an average particle diameter in the range of 20 nm to 300 nm,
The magnetic body is oriented so as to form an angle within a range of -10 degrees to 10 degrees or an angle within a range of 80 degrees to 100 degrees with an axis in a direction parallel to the direction of gravity in the cured resin material. The cured body according to claim 1, wherein the magnetic body is oriented so as to form an angle within the range of 80 degrees to 100 degrees with an axis in a direction parallel to the direction of gravity in the cured resin material. The cured body according to claim 1, wherein a ratio (B/A) of a crystal size (A) of the magnetic particles to an average particle diameter (B) of the magnetic particles is in a range of 1.5 to 10. The cured body according to claim 1, wherein the magnetic particles are represented by the following Chemical Formula 1:
[Formula 1]
MX _a O _b
In Formula 1, M is a metal or metal oxide, X includes Fe, Mn, Co, Ni or Zn, |a × c| = |b × d|, where c is the cation charge of X, and d is the anion charge of oxygen. The method of claim 1, wherein the surface treatment agent comprises a polyol-based compound, a polysiloxane-based compound, an alkyl phosphoric acid-based surface treatment agent, an alkyl carboxylic acid-based surface treatment agent, an alkyl sulfonic acid-based surface treatment agent, and a long-chain alkyl group. A cured product which is an acrylic copolymer containing an acid compound, an acidic functional group or an amino group, an aromatic acid-based surface treatment agent, and a block copolymer containing an acidic functional group or an amino group. The cured body according to claim 1, wherein the surface treatment agent has an acid value in the range of 10 to 400 mgKOH/g, or an amine value in the range of greater than 0 mgKOH/g to 20 mgKOH/g or less. The cured body according to claim 1, wherein the magnetic body contains the surface treatment agent in an amount within the range of 0.01 parts by weight to 30 parts by weight based on 100 parts by weight of the magnetic particles. The cured body according to claim 1, wherein the magnetic body further comprises a secondary surface treatment agent bonded to the surface treatment agent. The cured body according to claim 8, wherein the secondary surface treatment agent is a polyurethane-based surface treatment agent, a polyurea-based surface treatment agent, a poly(urethane-urea)-based surface treatment agent, or a branched polyester-based surface treatment agent. The cured body according to claim 8, wherein the magnetic body comprises 0.01 parts by weight to 30 parts by weight of the secondary surface treatment agent relative to 100 parts by weight of the magnetic particles. The cured body according to claim 1, wherein the coefficient of variation of the particle size of the magnetic particles in the magnetic powder is in the range of 5% to 30%. The cured body according to claim 1, wherein the magnetic powder has a saturation magnetization value in a range of 20 emu/g to 150 emu/g. The cured body according to claim 1, wherein the magnetic powder has a coercive force in a range of 1 kOe to 200 kOe. The cured body according to claim 1, wherein the magnetic powder has a BET specific surface area in a range of 3 m ² /g to 25 m ² /g. The cured body according to claim 1, wherein the magnetic powder has an SAR value of 80 W/g or more according to Equation 2:
[Formula 2]
SAR = Ci×m×ΔT/Δt
In Equation 2, SAR means the calorific value of the magnetic fluid obtained by dissolving the magnetic powder in water, Ci is the specific heat of water, which is the solvent of the magnetic fluid, 4.184 J/(g×K), and m is the amount of heat of the magnetic fluid _{The ratio (m i} /m _A ) of the weight (m _i , unit: g) of the solvent water (m i , unit: g) and the weight (m _A , unit: g) of the magnetic powder, ΔT is 0.35 mL of the magnetic fluid at a temperature of 294 K is the amount of temperature increase (unit: K) of the magnetic fluid when an alternating magnetic field is applied for 60 seconds under the conditions of a current of 120.4 A and a frequency of 310 kHz, and Δt is the time when the alternating magnetic field under the conditions is applied to the magnetic fluid is 60 seconds. According to claim 1, wherein the resin is an alkenyl group, an acryloyl group, a methacryloyl group, an epoxy group, an oxetane group, an alkenyl group, a hydrogen atom bonded to a silicon atom, an isocyanate group, a hydroxyl group, a phthalonitrile group or a carboxyl group A hardening body comprising. According to claim 1, wherein the resin is polysilicon resin, polyimide, polyetherimide, polyesterimide, acrylic resin, vinyl-based resin, olefin resin, polyurethane resin, isocyanate resin, acrylic resin, polyester resin, phthalo A cured product that is a nitrile resin, polyamic acid, polyamide or epoxy resin. A method for producing a cured body comprising the step of curing the curable composition by applying an electromagnetic field to the curable composition comprising a curable resin and a magnetic powder, the method comprising:
The magnetic powder includes magnetic particles and a magnetic body including a surface treatment agent introduced to the surface of the magnetic particles,
The magnetic particles are multi-domain magnetic particles including two or more crystals having a size in the range of 10 nm to 40 nm, and have an average particle diameter in the range of 20 nm to 300 nm,
In the curing step of the curable composition, the electromagnetic field is applied in a direction forming an angle within a range of -10 degrees to 10 degrees or an angle within a range of 80 degrees to 100 degrees with an axis in a direction parallel to the direction of gravity. The method of claim 18, wherein, in the curing of the curable composition, the electromagnetic field is applied in a direction forming an angle within a range of 80 degrees to 100 degrees with an axis in a direction parallel to a direction of gravity. The method of claim 18, wherein in the curing step of the curable composition, an electromagnetic field is applied at a magnetic flux density within a range of 1 mT to 100 mT. The method according to claim 18, wherein, in the curing step of the curable composition, an electromagnetic field is applied for a time in the range of 1 minute to 60 minutes.

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