Magnesium oxide

Abstract

The purpose of the present disclosure is to provide magnesium oxide having good moisture resistance. A magnesium oxide according to the present disclosure has a dyne value of less than 50 mN / m, and has a specific surface area of not less than 0.01 m2 / g but less than 1.3 m2 / g.

Description

Magnesium oxide

[0001] The present disclosure relates to magnesium oxide.

[0002] Magnesium oxide can be used as a thermally conductive material, heat-resistant material, electrical insulating material, filler, optical material, abrasive, etc. Patent Document 1 describes a method for producing magnesium oxide, in which magnesium hydroxide having a predetermined particle size and BET specific surface area is fired at 1100 to 1600°C, and then pulverized and classified to have a secondary particle size of 20 μm or less.

[0003] Patent Document 2 states that (C ｋ H （２ｋ＋１） ) ｎ -S (OC ｍ H （２ｍ＋１） ) （４－ｎ） The document describes a thermally conductive filler that is magnesium oxide having a predetermined BET specific surface area and average secondary particle size, the magnesium oxide being surface-coated with a coating agent represented by [k: 6 or more, m: 2 or less, n: 1 to 3] in an amount of 1 to 10 mass % based on the magnesium oxide.

[0004] JP 6-171928 A JP 2011-68757 A

[0005] The present disclosure aims to provide magnesium oxide having good moisture resistance. Preferably, the present disclosure aims to provide magnesium oxide that, when mixed with a resin, can suppress an increase in viscosity of the mixture. Also, preferably, the present disclosure aims to provide magnesium oxide that, when mixed with a resin, can suppress an increase in torque during stirring of the mixture.

[0006] The first embodiment of the present disclosure provides magnesium oxide having a dyne value of less than 50 mN / m. The specific surface area of ​​the magnesium oxide is less than 0.01 m. ２ / g or more 1.3m ２ / g.

[0007] In the I-2 embodiment of the present disclosure, in the I-1 embodiment, the average particle size of the magnesium oxide may be 0.5 μm or more and 50 μm or less.

[0008] In embodiment I-3 of the present disclosure, in any one of embodiments I-1 and I-2, the magnesium oxide may have a surface treatment layer. In embodiment I-3 of the present disclosure, in any one of embodiments I-1 and I-2, the surface treatment layer may be formed using a surface treatment agent containing a silane coupling agent.

[0009] In the I-4 embodiment of the present disclosure, in any one of the I-3 embodiments, the silane coupling agent is represented by the following formula (1): １ ｎ -S(OR ２ ) ｍ ...(1) R in the above formula (1) １ are each independently -L １ -R ３ L in the above formula (1) can represent １ may each independently represent a single bond or a divalent organic group. ３ are each independently C １－３０ Alkyl group, C ２－３０ Alkenyl group, C ６－３０ Aromatic hydrocarbon groups and -SiR ４ ３ R in the above formula (1) may represent one selected from the group consisting of ４ are each independently C １－６ R in the above formula (1) may represent a hydrocarbon group. ２ are each independently C １－４ It may represent an alkyl group or a hydrogen atom. n in the above formula (1) may represent an integer of 1 to 3. m in the above formula (1) may represent an integer of 1 to 3.

[0010] In the I-5 embodiment of the present disclosure, in any one of the I-3 and I-4 embodiments, the following formula (2): [In formula (2), n ｓ represents the amount of the silane coupling agent (mol), and N Ａ is Avogadro's number (mol －１ ) and S ｓis the area occupied by one molecule of the silane coupling agent (m ２ ), m ｍ represents the amount of magnesium oxide added (g), and s ｍ is the specific surface area of ​​magnesium oxide (m ２ ・g －１ ) represents the value r ｓ may be 100% or more and 4,000% or less.

[0011] Embodiment I-6 of the present disclosure provides magnesium oxide having a torque measured by the following method of 50 N·m or less. Furthermore, in Embodiment I-6 of the present disclosure, in any one of Embodiments I-1 to I-5, the torque measured by the following method may be 50 N·m or less. [Method for Measuring Torque] An ethylene-octene polyolefin resin is heated to 120°C and kneaded for 10 minutes, and then magnesium oxide is added to the ethylene-octene polyolefin resin so that the volume ratio of the ethylene-octene polyolefin resin to the magnesium oxide is 51:49. The mixture is further kneaded at 120°C for 15 minutes, and the torque (N·m) is measured at a rotation speed of 30 rpm.

[0012] In an I-7 embodiment of the present disclosure, in any one of the I-1 to I-6 embodiments, the magnesium oxide may have a surface treatment layer. The surface treatment layer may be formed using a surface treatment agent containing a silane coupling agent. The silane coupling agent is represented by the following formula (1): R １ ｎ -S(OR ２ ) ｍ ...(1) R in the above formula (1) １ are each independently -L １ -R ３ L in the above formula (1) can represent １ may each independently represent a single bond or a divalent organic group. ３ are each independently C １－３０ Alkyl group, C ２－３０ Alkenyl group, C ６－３０Aromatic hydrocarbon groups and -SiR ４ ３ groups, and preferably each independently represents one selected from C １－３０ Alkyl group and C ２－３０ R in the above formula (1) may represent one selected from the group consisting of alkyl, aryl, aryl, aryl and aryl groups. ４ are each independently C １－６ R in the above formula (1) may represent a hydrocarbon group. ２ are each independently C １－４ It may represent an alkyl group or a hydrogen atom. n in the above formula (1) may represent an integer of 1 to 3. m in the above formula (1) may represent an integer of 1 to 3.

[0013] Embodiment I-8 of the present disclosure provides magnesium oxide having a viscosity of 70 Pa·s or less, measured by the following method. Furthermore, in Embodiment I-8 of the present disclosure, in any one of Embodiments I-1 to I-7, the viscosity, measured by the following method, may be 70 Pa·s or less. [Method of Measuring Viscosity] Bisphenol-type epoxy resin and magnesium oxide are mixed to a volume ratio of 70:30. The mixture is stirred at 25°C for 1 hour at a rotation speed of 500 rpm to obtain a resin composition. Using a rheometer, disposable parallel plates with a diameter of 25 mm and a disposable cup with a diameter of 80 mm are used, and the viscosity is measured at a temperature of 25°C, a gap distance of 1 mm, and a shear rate range of 0 to 20 s －１ The viscosity (Pa·s) is measured under the conditions of 100° C., 100° C., and 20 seconds of measurement time.

[0014] In an I-9 embodiment of the present disclosure, in any one of the I-1 to I-8 embodiments, the magnesium oxide may have a surface treatment layer. The surface treatment layer may be formed using a surface treatment agent containing a silane coupling agent. The silane coupling agent is represented by the following formula (1): R １ ｎ -S(OR ２ ) ｍ ...(1) R in the above formula (1) １ are each independently -L １ -R３ L in the above formula (1) can represent １ may each independently represent a single bond or a divalent organic group. ３ are each independently C １－３０ Alkyl group, C ２－３０ Alkenyl group, C ６－３０ Aromatic hydrocarbon groups and -SiR ４ ３ groups, and preferably each independently represents one selected from the group consisting of C ２－３０ Alkenyl group and C ６－３０ R in the above formula (1) may represent one selected from the group consisting of aromatic hydrocarbon groups. ４ are each independently C １－６ R in the above formula (1) may represent a hydrocarbon group. ２ are each independently C １－４ It may represent an alkyl group or a hydrogen atom. n in the above formula (1) may represent an integer of 1 to 3. m in the above formula (1) may represent an integer of 1 to 3.

[0015] An I-10 embodiment of the present disclosure provides magnesium oxide having a viscosity of 19 Pa·s or less, measured by the following method. Also, in an I-10 embodiment of the present disclosure, in any one of embodiments I-1 to I-9, the viscosity, measured by the following method, may be 70 Pa·s or less. [Method of Measuring Viscosity] A polyfunctional acrylic monomer and magnesium oxide are mixed to a volume ratio of 60:40. The mixture is stirred at 25°C for 1 hour at a rotation speed of 500 rpm to obtain a resin composition. Using a rheometer, disposable parallel plates with a diameter of 25 mm and a disposable cup with a diameter of 80 mm are used, and the viscosity is measured at a temperature of 23°C, a gap distance of 1 mm, and a shear rate range of 0 to 20 s －１ The viscosity (Pa·s) is measured under the conditions of 100° C., 100° C., and 20 seconds of measurement time.

[0016] In an I-11 embodiment of the present disclosure, in any one of the I-1 to I-10 embodiments, the magnesium oxide may have a surface treatment layer. The surface treatment layer may be formed using a surface treatment agent containing a silane coupling agent. The silane coupling agent is represented by the following formula (1): R １ ｎ -S(OR ２ ) ｍ ...(1) R in the above formula (1) １ are each independently -L １ -R ３ L in the above formula (1) can represent １ may each independently represent a single bond or a divalent organic group. ３ are each independently C １－３０ Alkyl group, C ２－３０ Alkenyl group, C ６－３０ Aromatic hydrocarbon groups and -SiR ４ ３ groups, and preferably each independently represents one selected from the group consisting of C ２－３０ Alkenyl group and C ６－３０ R in the above formula (1) may represent one selected from the group consisting of aromatic hydrocarbon groups. ４ are each independently C １－６ R in the above formula (1) may represent a hydrocarbon group. ２ are each independently C １－４ It may represent an alkyl group or a hydrogen atom. n in the above formula (1) may represent an integer of 1 to 3. m in the above formula (1) may represent an integer of 1 to 3.

[0017] A I-12th embodiment of the present disclosure provides a method for producing magnesium oxide, which includes surface-treating a first magnesium oxide with a surface treatment agent including a silane coupling agent to obtain a second magnesium oxide having a surface treatment layer, wherein the surface treatment is carried out by a wet treatment.

[0018] In an I-13 embodiment of the present disclosure, in the I-12 embodiment, the surface treatment may be carried out by a treatment method including mixing an organic solvent with a first magnesium oxide to obtain a first mixed liquid. The treatment method may include mixing the surface treatment agent with the first mixed liquid to obtain a second mixed liquid. The treatment method may include removing the organic solvent from the second mixed liquid to obtain a precursor of a second magnesium oxide. The treatment method may include heating and / or drying the precursor of the second magnesium oxide to obtain a second magnesium oxide having a surface treatment layer.

[0019] An I-14 embodiment of the present disclosure provides a heat dissipation member including the magnesium oxide according to any one of the I-1 to I-11 embodiments.

[0020] An I-15 embodiment of the present disclosure provides a thermally conductive filler comprising the magnesium oxide according to any one of the I-1 to I-11 embodiments.

[0021] A I-16th embodiment of the present disclosure provides a device including the heat dissipation member according to any one of the I-14th embodiments.

[0022] Embodiment II-1 of the present disclosure provides magnesium oxide having a dyne value of less than 45 mN / m.

[0023] In the II-2 embodiment of the present disclosure, in the II-1 embodiment, the specific surface area of ​​the magnesium oxide is 1.3 m ２ / g or more 10m ２ / g or less.

[0024] In a II-3 embodiment of the present disclosure, in any one of the II-1 embodiment and the II-2 embodiment, the average particle size of the magnesium oxide may be 0.5 μm or more and 50 μm or less.

[0025] In the second-fourth embodiment of the present disclosure, in any one of the first and second embodiments, the magnesium oxide may have a surface treatment layer. The surface treatment layer may be formed using a surface treatment agent containing a silane coupling agent.

[0026] In a second-fifth embodiment of the present disclosure, in any one of the second-fourth embodiments, the silane coupling agent is represented by the following formula (1): １ ｎ -Si-(OR ２ ) ｍ ...(1) R in the above formula (1) １ are each independently -L １ -R ３ L in the above formula (1) can represent １ may each independently represent a single bond or a divalent organic group. ３ are each independently C １－３０ Alkyl group, C ２－３０ Alkenyl group, C ６－３０ Aromatic hydrocarbon groups and -SiR ４ ３ R in the above formula (1) may represent one selected from the group consisting of ４ are each independently C １－６ R in the above formula (1) may represent a hydrocarbon group. ２ are each independently C １－４ It may represent an alkyl group or a hydrogen atom. n in the above formula (1) may represent an integer of 1 to 3. m in the above formula (1) may represent an integer of 1 to 3.

[0027] In the II-6 embodiment of the present disclosure, in any one of the II-4 embodiment and the II-5 embodiment, the following formula (2): [In formula (2), n ｓ represents the amount of the silane coupling agent (mol), and N Ａ is Avogadro's number (mol －１ ) and S ｓ is the area occupied by one molecule of the silane coupling agent (m ２ ), m ｍ represents the amount of magnesium oxide added (g), and s ｍ is the specific surface area of ​​magnesium oxide (m ２ ・g －１ ) represents the value rｓ However, it may be 40% or more and 500% or less.

[0028] Embodiment II-7 of the present disclosure provides magnesium oxide having a torque measured by the following method of 53 N m or less. Furthermore, Embodiment II-7 of the present disclosure may be any one of Embodiments II-1 to II-6, in which the torque measured by the following method is 53 N m or less. [Method for Measuring Torque] An ethylene-octene polyolefin resin is heated to 120°C and kneaded for 10 minutes, and then magnesium oxide is added to the ethylene-octene polyolefin resin so that the volume ratio of the ethylene-octene polyolefin resin to the magnesium oxide is 51:49, and the mixture is further kneaded at 120°C for 15 minutes, and the torque (N m) is measured under conditions of a rotation speed of 30 rpm.

[0029] In a II-8 embodiment of the present disclosure, in any one of the II-1 to II-7 embodiments, the magnesium oxide may have a surface treatment layer. The surface treatment layer may be formed using a surface treatment agent containing a silane coupling agent. The silane coupling agent is represented by the following formula (1): R １ ｎ -Si-(OR ２ ) ｍ ...(1) R in the above formula (1) １ are each independently -L １ -R ３ L in the above formula (1) can represent １ may each independently represent a single bond or a divalent organic group. ３ are each independently C １－３０ Alkyl group, C ２－３０ Alkenyl group, C ６－３０ Aromatic hydrocarbon groups and -SiR ４ ３ groups, and preferably each independently represents one selected from the group consisting of C １－３０ Alkyl group and —SiR ４ ３R in the above formula (1) may represent one selected from the group consisting of ４ are each independently C １－６ R in the above formula (1) may represent a hydrocarbon group. ２ are each independently C １－４ It may represent an alkyl group or a hydrogen atom. n in the above formula (1) may represent an integer of 1 to 3. m in the above formula (1) may represent an integer of 1 to 3.

[0030] Embodiment II-9 of the present disclosure provides magnesium oxide having a viscosity of 130 Pa·s or less, measured by the following method. Furthermore, in Embodiment II-9 of the present disclosure, in any one of Embodiments II-1 to II-8, the viscosity measured by the following method may be 130 Pa·s or less. [Method of Measuring Viscosity] Bisphenol-type epoxy resin and magnesium oxide are mixed to a volume ratio of 70:30. The mixture is stirred at 25°C for 1 hour at a rotation speed of 500 rpm to obtain a resin composition. Using a rheometer, disposable parallel plates with a diameter of 25 mm and a disposable cup with a diameter of 80 mm are used, and the viscosity is measured at a temperature of 25°C, a gap distance of 1 mm, and a shear rate range of 0 to 20 s －１ The viscosity (Pa·s) is measured under the conditions of 100° C., 100° C., and 20 seconds of measurement time.

[0031] In a II-10 embodiment of the present disclosure, in any one of the II-1 to II-9 embodiments, the magnesium oxide may have a surface treatment layer. The surface treatment layer may be formed using a surface treatment agent containing a silane coupling agent. The silane coupling agent is represented by the following formula (1): R １ ｎ -Si-(OR ２ ) ｍ ...(1) R in the above formula (1) １ are each independently -L １ -R ３ L in the above formula (1) can represent １ may each independently represent a single bond or a divalent organic group.３ are each independently C １－３０ Alkyl group, C ２－３０ Alkenyl group, C ６－３０ Aromatic hydrocarbon groups and -SiR ４ ３ groups, preferably C ２－３０ Alkenyl group and C ６－３０ R in the above formula (1) may represent one selected from the group consisting of aromatic hydrocarbon groups. ４ are each independently C １－６ R in the above formula (1) may represent a hydrocarbon group. ２ are each independently C １－４ It may represent an alkyl group or a hydrogen atom. n in the above formula (1) may represent an integer of 1 to 3. m in the above formula (1) may represent an integer of 1 to 3.

[0032] Embodiment II-11 of the present disclosure provides magnesium oxide having a viscosity of 27 Pa·s or less, as measured by the following method. Furthermore, in Embodiment II-11 of the present disclosure, in any one of Embodiments II-1 to II-10, the viscosity, as measured by the following method, may be 27 Pa·s or less. [Method of Measuring Viscosity] A polyfunctional acrylic monomer and magnesium oxide are mixed to a volume ratio of 60:40. The mixture is stirred at 25°C for 1 hour at a rotation speed of 500 rpm to obtain a resin composition. Using a rheometer, disposable parallel plates with a diameter of 25 mm and a disposable cup with a diameter of 80 mm are used, and the viscosity is measured at a temperature of 23°C, a gap distance of 1 mm, and a shear rate range of 0 to 20 s －１ The viscosity (Pa·s) is measured under the conditions of 100° C., 100° C., and 20 seconds of measurement time.

[0033] In a II-12 embodiment of the present disclosure, in any one of the II-1 to II-11 embodiments, the magnesium oxide may have a surface treatment layer. The surface treatment layer may be formed using a surface treatment agent containing a silane coupling agent. The silane coupling agent is represented by the following formula (1): R １ ｎ -Si-(OR２ ) ｍ ...(1) R in the above formula (1) １ are each independently -L １ -R ３ L in the above formula (1) can represent １ may each independently represent a single bond or a divalent organic group. ３ are each independently C １－３０ Alkyl group, C ２－３０ Alkenyl group, C ６－３０ Aromatic hydrocarbon groups and -SiR ４ ３ groups, and preferably each independently represents one selected from the group consisting of C ２－３０ Alkenyl group and C ６－３０ R in the above formula (1) may represent one selected from the group consisting of aromatic hydrocarbon groups. ４ are each independently C １－６ R in the above formula (1) may represent a hydrocarbon group. ２ are each independently C １－４ It may represent an alkyl group or a hydrogen atom. n in the above formula (1) may represent an integer of 1 to 3. m in the above formula (1) may represent an integer of 1 to 3.

[0034] A II-13th embodiment of the present disclosure provides a method for producing magnesium oxide, which includes surface-treating a first magnesium oxide with a surface treatment agent including a silane coupling agent to obtain a second magnesium oxide having a surface treatment layer, wherein the surface treatment is carried out by a wet treatment.

[0035] In a II-14 embodiment of the present disclosure, in the II-13 embodiment, the surface treatment may be carried out by a treatment method including mixing an organic solvent with a first magnesium oxide to obtain a first mixed liquid. The treatment method may include mixing the surface treatment agent with the first mixed liquid to obtain a second mixed liquid. The treatment method may include removing the organic solvent from the second mixed liquid to obtain a precursor of a second magnesium oxide. The treatment method may include heating and / or drying the precursor of the second magnesium oxide to obtain a second magnesium oxide having a surface treatment layer.

[0036] A II-15th embodiment of the present disclosure provides a heat dissipation member including the magnesium oxide according to any one of the II-1 to II-12 embodiments.

[0037] A II-16 embodiment of the present disclosure provides a thermally conductive filler comprising the magnesium oxide according to any one of the II-1 to II-12 embodiments.

[0038] A II-17th embodiment of the present disclosure provides a device including the heat dissipation member according to any one of the II-15th embodiments.

[0039] According to the present disclosure, it is possible to provide magnesium oxide with good moisture resistance. Preferably, the present disclosure can provide magnesium oxide with low viscosity, which can suppress an increase in viscosity of a mixture when mixed with a resin. Also, it is possible to provide magnesium oxide with low viscosity, which can suppress an increase in torque during stirring of the mixture when mixed with a resin.

[0040] In Aspect I, the magnesium oxide of the present disclosure has a dyne value of less than 50 mN / m. In Aspect II, the magnesium oxide of the present disclosure has a dyne value of less than 45 mN / m. Unless otherwise specified, the following description is applicable to both Aspects I and II.

[0041] The magnesium oxide of the present disclosure has good moisture resistance. In a preferred embodiment, the magnesium oxide of the present disclosure has excellent moisture resistance even when used for a long period of time. Therefore, the magnesium oxide of the present disclosure has excellent moisture resistance even when used for a long period of time. Therefore, the magnesium oxide of the present disclosure has excellent moisture resistance even when used for a long period of time. ２ The formation of hydroxybenzoates can be suppressed, and acid resistance can also be improved. Furthermore, the magnesium oxide of the present disclosure can have good affinity with resins and good dispersibility in resins. As a result, the thermal conductivity of resin materials containing the magnesium oxide of the present disclosure can be improved. Although the present disclosure should not be interpreted as being limited to a particular theory, the reason why the magnesium oxide of the present disclosure can have good moisture resistance is thought to be as follows.

[0042] In other words, the dyne value can be an index of surface free energy, and a larger dyne value indicates a higher surface free energy, while a smaller dyne value indicates a lower surface free energy. In the magnesium oxide of the present disclosure, it is believed that by lowering the surface free energy, interaction with water can be suppressed, resulting in good moisture resistance.

[0043] In the present disclosure, "magnesium oxide" is not limited to magnesium oxide as a compound, but may also include materials that contain magnesium oxide as a main component and have been subjected to treatments such as surface treatment. In this specification, magnesium oxide as a compound may be referred to as "MgO." Note that magnesium oxide (MgO) as the compound may contain elements such as Ca, Si, Cl, S, Al, and Fe as impurities.

[0044] In Aspect I, the dyne value of the magnesium oxide is less than 50 mN / m, preferably 15 mN / m or more and 50 mN / m or less, more preferably 20 mN / m or more and 45 mN / m or less. The dyne value of the magnesium oxide is preferably 50 mN / m or less, more preferably 45 mN / m or less, even more preferably 40 mN / m or less, and is preferably 15 mN / m or more, more preferably 20 mN / m or more.

[0045] In Aspect II, the dyne value of the magnesium oxide is less than 45 mN / m, preferably 15 mN / m or more and 40 mN / m or less, more preferably 20 mN / m or more and 35 mN / m or less. The dyne value of the magnesium oxide is preferably 45 mN / m or less, more preferably 40 mN / m or less, even more preferably 35 mN / m or less, and is preferably 15 mN / m or more, more preferably 20 mN / m or more.

[0046] The dyne value of magnesium oxide can be measured by the following method. [Method for Measuring Dyne Value] Solutions with dyne values ​​of 25.4 mN / m, 30.0 mN / m, 35.0 mN / m, 40.0 mN / m, 45.0 mN / m, and 50.0 mN / m and water are prepared. 2 mL of each solution is measured into a clean glass container, and the liquid temperature is adjusted to 25°C. The glass container used is one in which the liquid level is 5 mm or higher from the inner bottom. Next, the measurement sample is dried at 60°C for 1 hour, and then the temperature of the measurement sample is adjusted to 25°C. Thereafter, 0.01 g of the measurement sample is sprinkled onto the surface of each liquid. 10 seconds after addition, the lowest dyne value of the liquid in which the measurement sample is completely floating on the liquid surface is determined as the dyne value of the sample.

[0047] In the present disclosure, the magnesium oxide may preferably be magnesium oxide particles. In the present disclosure, "particles" refers to an aggregate of particulate materials that are independent of each other. The shape of each particle may be spherical, irregular, or the like. When the shape of each particle is spherical, "spherical" is not limited to "true spherical."

[0048] In embodiment I, the specific surface area of ​​the magnesium oxide is 0.01 m ２ / g or more 1.3m ２ / g, preferably less than 0.05m ２ / g or more 1m ２ / g or less, more preferably 0.1m ２ / g or more 1.0m ２ The specific surface area of ​​magnesium oxide can be 0.01 m / g or less. ２ / g or more, preferably 0.05m ２ / g or more, more preferably 0.1 m２ / g or more, and 1.3m ２ / g, preferably less than 1 m ２ / g or less, more preferably 1.0m ２ Since the specific surface area of ​​magnesium oxide is within the above range, it is easy to control the interface between the magnesium oxide particles and a resin, and when mixed with a resin, it is easy to suppress increases in viscosity and torque of the mixture.

[0049] In embodiment II, the specific surface area of ​​the magnesium oxide is preferably 1.3 m ２ / g or more 10m ２ / g or less, more preferably 1.3m ２ / g or more 5.0m ２ / g or less, more preferably 1.3m ２ / g or more 3.0m ２ The specific surface area of ​​magnesium oxide is preferably 1.3 m / g or less. ２ / g or more, preferably 10m ２ / g or less, more preferably 5.0m ２ / g or less, more preferably 3.0m ２ When the specific surface area of ​​magnesium oxide is within the above range, it is easy to control the interface between the magnesium oxide particles and a resin, and when mixed with a resin, it is easy to suppress an increase in the viscosity and torque of the mixture.

[0050] The specific surface area of ​​magnesium oxide is preferably 0.01 m ２ / g or more 10m ２ / g or less, more preferably 0.05m ２ / g or more 5.0m ２ / g or less, more preferably 0.1m ２ / g or more 3.0m ２ The specific surface area of ​​the magnesium oxide is preferably 0.01 m / g or less. ２ / g or more, more preferably 0.05m ２ / g or more, more preferably 0.1m ２ / g or more, preferably 10m ２ / g or less, more preferably 5.0m ２ / g or less, more preferably 3.0m ２ / g or less.

[0051] In the present disclosure, the specific surface area can be measured by the BET method, and specifically, can be measured in accordance with JIS Z 8830.

[0052] In Aspect I, the average particle size of the magnesium oxide may be preferably 0.5 μm or more and 50 μm or less, more preferably 1.0 μm or more and 40 μm or less, and even more preferably 1.5 μm or more and 35 μm or less. The average particle size of the magnesium oxide may be preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 1.5 μm or more, and may be preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 35 μm or less. Since the average particle size of the magnesium oxide is within the above range, it is easy to control the surface condition of the magnesium oxide, moisture resistance may be good, and viscosity and torque may be low when mixed with a resin.

[0053] In Aspect II, the average particle size of the magnesium oxide may be preferably 0.5 μm or more and 10 μm or less, more preferably 1.0 μm or more and 8 μm or less, and even more preferably 1.5 μm or more and 5 μm or less. The average particle size of the magnesium oxide may be preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 1.5 μm or more, and may be preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 5 μm or less. Since the average particle size of the magnesium oxide is within the above range, it is easy to control the surface condition of the magnesium oxide, moisture resistance may be good, and viscosity and torque may be low when mixed with a resin.

[0054] The average particle size of magnesium oxide is preferably 0.5 μm or more and 50 μm or less, more preferably 1.0 μm or more and 40 μm or less, and even more preferably 1.5 μm or more and 30 μm or less. The average particle size of magnesium oxide is preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 1.5 μm or more, and is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less.

[0055] In the present disclosure, the average particle size can be measured by a microtrack method and can be the volume-based median size (D50).

[0056] In embodiment I, the magnesium oxide has a specific surface area of ​​0.01 m ２ / g or more 1.3m ２ / g, the average particle size is preferably 0.5 μm or more and 50 μm or less, and the specific surface area is preferably 0.05 m ２ / g or more 1.3m ２ / g or less, and more preferably, the average particle size is 1.0 μm or more and 40 μm or less, and the specific surface area is 0.1 m ２ / g or more 1.0m ２ / g or less, and the average particle size is more preferably 1.5 μm or more and 30 μm or less.

[0057] In embodiment II, the magnesium oxide has a specific surface area of ​​1.3 m ２ / g or more 10m ２ / g or less, the average particle size is preferably 0.5 μm or more and 10 μm or less, and the specific surface area is preferably 1.3 m ２ / g or more 5.0m ２ / g or less, and more preferably, the average particle size is 1.0 μm or more and 8 μm or less, and the specific surface area is 1.3 m ２ / g or more 3.0m ２ / g or less, and the average particle size is more preferably 1.5 μm or more and 5 μm or less.

[0058] Magnesium oxide has a specific surface area of ​​0.01 m ２ / g or more 10m ２ / g or less, the average particle size is preferably 0.5 μm or more and 50 μm or less, and the specific surface area is preferably 0.05 m ２ / g or more 5m ２ / g or less, and more preferably, the average particle size is 1.0 μm or more and 40 μm or less, and the specific surface area is 0.1 m ２ / g or more 3m ２ / g or less, and the average particle size is more preferably 1.5 μm or more and 30 μm or less.

[0059] In Aspect I, the magnesium oxide has a torque measured by the following method of preferably 50 N m or less, more preferably 45 N m or less, even more preferably 40 N m or less, and may be, for example, 10 N m or more, 15 Pa s or more, or even 20 N m or more. In Aspect II, the magnesium oxide has a torque measured by the following method of preferably 53 N m or less, more preferably 50 N m or less, even more preferably 45 N m or less, or even more preferably 40 N m or less, and may be, for example, 10 N m or more, 15 Pa s or more, or even 20 N m or more. [Method for measuring torque] An ethylene-octene polyolefin resin is heated to 120°C and kneaded for 10 minutes, and then magnesium oxide is added to the ethylene-octene polyolefin resin so that the volume ratio of the ethylene-octene polyolefin resin to the magnesium oxide becomes 51:49. The mixture is further kneaded at 120°C for 15 minutes, and the torque (N m) is measured at a rotation speed of 30 rpm.

[0060] In this case, in Aspect I, the magnesium oxide preferably has a surface treatment layer, and the surface treatment layer is preferably formed using a surface treatment agent containing a silane coupling agent. Such a silane coupling agent preferably contains a compound represented by formula (1) described below, and more preferably contains a compound represented by formula (I-1') described below. Also, in this case, in Aspect II, the magnesium oxide preferably has a surface treatment layer, and the surface treatment layer is preferably formed using a surface treatment agent containing a silane coupling agent. Such a silane coupling agent preferably contains a compound represented by formula (1) described below, and more preferably contains a compound represented by formula (II-1') described below.

[0061] In Aspect I, the viscosity of the magnesium oxide, as measured by the following method (i), is preferably 70 Pa s or less, more preferably 67 Pa s or less, and even more preferably 65 Pa s or less, and may be, for example, 10 Pa s or more, 15 Pa s or more, or even 20 Pa s or more. In Aspect II, the viscosity of the magnesium oxide, as measured by the following method (i), is preferably 130 Pa s or less, more preferably 120 Pa s or less, and even more preferably 110 Pa s or less, and may be, for example, 40 Pa s or more, 50 Pa s or more, or even 60 Pa s or more. [Viscosity Measurement Method (i)] A bisphenol epoxy resin and magnesium oxide are mixed at a volume ratio of 70:30. The mixture is stirred at 25°C for 1 hour at 500 rpm to obtain a resin composition. Using a rheometer, disposable parallel plates with a diameter of 25 mm and disposable cups with a diameter of 80 mm were used, the temperature was 25°C, the gap distance was 1 mm, and the measurement shear rate range was 0 to 20 s －１ The viscosity (Pa·s) is measured under the conditions of 100° C., 100° C., and 20 seconds of measurement time.

[0062] In this case, in Aspect I, the magnesium oxide preferably has a surface treatment layer, and the surface treatment layer is preferably formed using a surface treatment agent containing a silane coupling agent. Such a silane coupling agent preferably contains a compound represented by formula (1) described below, and more preferably contains a compound represented by formula (I-1″) described below. Also, in this case, in Aspect II, the magnesium oxide preferably has a surface treatment layer, and the surface treatment layer is preferably formed using a surface treatment agent containing a silane coupling agent. Such a silane coupling agent preferably contains a compound represented by formula (1) described below, and more preferably contains a compound represented by formula (II-1″) described below.

[0063] In Aspect I, the viscosity of the magnesium oxide, as measured by the following method (ii), is preferably 19 Pa s or less, more preferably 18 Pa s or less, and even more preferably 17 Pa s or less, and may be, for example, 10 Pa s or more, or even 15 Pa s or more. In Aspect II, the viscosity of the magnesium oxide, as measured by the following method (ii), is preferably 27 Pa s or less, more preferably 26 Pa s or less, and even more preferably 25 Pa s or less, and may be, for example, 10 Pa s or more, 15 Pa s or more, or even 20 Pa s or more. [Viscosity Measurement Method (ii)] A polyfunctional acrylic monomer and magnesium oxide are mixed at a volume ratio of 60:40. The mixture is stirred at 25°C for 1 hour at 500 rpm to obtain a resin composition. Using a rheometer, disposable parallel plates with a diameter of 25 mm and disposable cups with a diameter of 80 mm were used, the temperature was 23°C, the gap distance was 1 mm, and the measurement shear rate range was 0 to 20 s －１ The viscosity (Pa·s) is measured under the conditions of 100° C., 100° C., and 20 seconds of measurement time.

[0064] In this case, in Aspect I, the magnesium oxide of the present disclosure preferably has a surface treatment layer, and the surface treatment layer is preferably formed using a surface treatment agent containing a silane coupling agent. Such a silane coupling agent preferably contains a compound represented by formula (1) described below, and more preferably contains a compound represented by formula (I-1″) described below. Also in this case, in Aspect II, the magnesium oxide of the present disclosure preferably has a surface treatment layer, and the surface treatment layer is preferably formed using a surface treatment agent containing a silane coupling agent. Such a silane coupling agent preferably contains a compound represented by formula (1) described below, and more preferably contains a compound represented by formula (II-1″) described below.

[0065] The magnesium oxide of the present disclosure can suppress an increase in torque when mixed with a resin. Furthermore, the magnesium oxide of the present disclosure can suppress an increase in viscosity when mixed with a resin. This reduces the load on the manufacturing equipment, and if the resin material containing magnesium oxide is liquid, it can be injected into confined spaces by improving its fluidity. If the resin material is solid, it is also expected to improve its moldability.

[0066] The magnesium oxide of the present disclosure preferably has a surface treatment layer on its surface. That is, the magnesium oxide of the present disclosure may be a material including MgO and a surface treatment layer provided on the surface of the MgO. The MgO may preferably be MgO particles. The surface treatment layer covers at least a portion, preferably the entire surface, of the MgO.

[0067] The surface treatment layer can be preferably formed using a surface treatment agent containing a silane coupling agent.

[0068] The silane coupling agent may be a compound having a hydrolyzable silyl group and a monovalent organic group. The hydrolyzable silyl group represents a Si atom to which a hydroxyl group or a hydrolyzable group is bonded.

[0069] The hydrolyzable group refers to a group that can generate a silanol group by hydrolysis. Examples of such a hydrolyzable group include -OR ａ１ , -OCOR ａ１ , halogen and hydrogen atoms. ａ１ is C １－４ It represents an alkyl group, and may be preferably a methyl group or an ethyl group.

[0070] The monovalent organic group may be a monovalent group containing carbon atoms, and may be a monovalent hydrocarbon group; a monovalent or divalent hydrocarbon group and —O—, —CO—, —NR ａ２ - and -SiR ａ３ ２ - may be a group consisting of one or more selected from the group consisting of ａ２ is C １－４ represents an alkyl group or a hydrogen atom, and R ａ３ is C １－６The divalent or higher valent organic group may be a group in which one or more hydrogen atoms contained in the monovalent organic group serve as bonds.

[0071] The monovalent hydrocarbon group is a monovalent group containing carbon and hydrogen, and may be a group having one hydrogen atom contained in a hydrocarbon compound as a bond. The hydrocarbon group is preferably C １－３０ The hydrocarbon group may be an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, or a group consisting of a combination of two or more groups selected from aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The aliphatic hydrocarbon group may be either linear or branched, and may be saturated or unsaturated. The divalent or higher hydrocarbon group may be a group in which one or more hydrogen atoms contained in the monovalent hydrocarbon group serve as bonds.

[0072] The molecular weight of the silane coupling agent may be preferably 130 or more and 10,000 or less, more preferably 140 or more and 6,000 or less. The larger the molecular weight of the silane coupling agent, the better the water resistance of the resulting magnesium oxide. In the present disclosure, the molecular weight of a silane coupling agent having a molecular weight of less than 500 may be calculated based on the structural formula of the silane coupling agent. Furthermore, the molecular weight of a silane coupling agent having a molecular weight of 500 or more means a weight average molecular weight, which can be measured by gel permeation chromatography and calculated as a converted value using polystyrene as a standard sample.

[0073] The silane coupling agent is preferably a compound represented by the following formula (1): １ ｎ -S(OR ２ ) ｍ ...(1) [In formula (1), R １ are each independently -L １ -R ３ represents L １ each independently represents a single bond or a divalent organic group; R ３ are each independently C １－３０ Alkyl group, C ２－３０ Alkenyl group, C ６－３０ Aromatic hydrocarbon groups and -SiR４ ３ R represents one selected from the group consisting of ４ are each independently C １－６ represents a hydrocarbon group, R ２ are each independently C １－４ represents an alkyl group or a hydrogen atom, n represents an integer of 1 to 3, and m represents an integer of 1 to 3.

[0074] R １ are each independently -L １ -R ３ Represents.

[0075] L １ each independently represents a single bond or a divalent organic group.

[0076] L １ The divalent organic group represented by the formula (I) includes a divalent hydrocarbon group; a divalent hydrocarbon group and —O—, —CO—, —NR ａ２ and -SiR ａ２ ２ - is a group obtained by combining one or more of the following:

[0077] L １ is preferably represented by the following formulas (i) to (iv): ａ４ -O-CO- ...(i) -R ａ４ -NR ａ２ -...(ii) -R ａ４ -NR ａ２ -CO-O- ...(iii) -R ａ４ -NR ａ２ -CO-O-R ａ５ - (OR ａ６ ) ｐ１ -(OSiR ａ３ ２ ) ｐ２ -...(iv) [In formulas (i) to (iv), R ａ２ is C １－４ represents an alkyl group or a hydrogen atom, ａ３ is C １－６ represents a hydrocarbon group, R ａ４ is C １－４ represents an alkylene group, ａ５ is C１－４ represents an alkylene group, ａ６ is C １－４ represents an alkylene group, p1 represents an integer of 1 to 5, and p2 represents an integer of 2 to 100.

[0078] In formulas (i) to (iv), preferably, R ａ４ One end of the side is bonded to the Si atom in formula (1), and the other end is bonded to R ３ and combine.

[0079] R ａ２ C represented by １－４ The alkyl group may be linear or branched, and is preferably a methyl group or an ethyl group. ａ２ is preferably a hydrogen atom.

[0080] R ａ３ C represented by １－６ The hydrocarbon group includes C １－６ Examples of the alkyl group include an alkyl group and a phenyl group. １－６ The alkyl group may be linear or branched, and is preferably C １－４ R is an alkyl group, more preferably a methyl group or an ethyl group, and even more preferably a methyl group. ａ３ As the alkyl group, a methyl group or a phenyl group is preferred.

[0081] R ａ４ C represented by １－４ The alkylene group may be linear or branched, and is preferably C ２－３ It may be an alkylene group.

[0082] R ａ５ C represented by １－４ The alkylene group may be linear or branched, and is preferably C ２－３ It may be an alkylene group.

[0083] R ａ６ C represented by １－４ The alkylene group may be linear or branched, and is preferably C ２－３ It may be an alkylene group.

[0084] p1 represents an integer of 1 to 5, preferably 1 to 3.

[0085] p2 represents an integer of 2 to 100, preferably 5 to 80, and more preferably 10 to 70.

[0086] L １ is preferably a single bond or a group represented by formula (i), (ii), (iii) or (iv), more preferably a single bond or a group represented by formula (i), (ii) or (iv).

[0087] R ３ is C １－３０ Alkyl group, C ２－３０ Alkenyl group, C ６－３０ Aromatic hydrocarbon groups and -SiR ４ ３ In one embodiment, preferably, １－３０ Alkyl group and C ２－３０ In another embodiment, it is preferably one selected from the group consisting of C ２－３０ Alkenyl group and C ６－３０ It may be one selected from the group consisting of aromatic hydrocarbon groups.

[0088] R ３ C represented by １－３０ The alkyl group may be linear or branched, and preferably branched. １－３０ The alkyl group is preferably a straight or branched C １－３０ alkyl group, more preferably a linear or branched C ５－２５ alkyl group, more preferably a linear or branched C １０－２０ alkyl groups, more preferably branched C １０－２０ It may be an alkyl group.

[0089] R ３ C represented by ２－３０ The alkenyl group may be linear or branched. ２－３０ The alkenyl group is preferably a linear or branched C ２－１５ Alkenyl groups are preferred, and linear or branched C ２－１０Alkenyl groups are preferred, and linear or branched C ２－７ Alkenyl groups, more preferably straight or branched C ２－４ It may be an alkenyl group.

[0090] R ３ C represented by ６－３０ The aromatic hydrocarbon group may be monocyclic or polycyclic, and is preferably monocyclic. ６－３０ The aromatic hydrocarbon group is preferably a monocyclic or polycyclic C ６－２０ It is an aromatic hydrocarbon group, more preferably a monocyclic or polycyclic C ６－１５ It is an aromatic hydrocarbon group, more preferably a monocyclic or polycyclic C ６－１０ It is an aromatic hydrocarbon group, more preferably a monocyclic C ６－８ It may be an aromatic hydrocarbon group. ３ Examples of the aromatic hydrocarbon group represented by the formula (I) include a phenyl group, a toluyl group, a xylyl group, a styryl group, and a naphthyl group.

[0091] R ４ C represented by １－６ The hydrocarbon group includes C １－６ Examples of the alkyl group include an alkyl group and a phenyl group. １－６ The alkyl group may be linear or branched, and is preferably C １－４ R is an alkyl group, more preferably a methyl group or an ethyl group, and even more preferably a methyl group. ４ As the alkyl group, a methyl group or a phenyl group is preferred.

[0092] In one embodiment, R ３ As for C １－３０ Alkyl group, C ２－３０ Alkenyl groups and —SiR ４ ３ In another embodiment, R ３ As for C １－３０ Alkyl group and C ２－３０ In yet another embodiment, R ３ As for C ２－３０Alkenyl group and C ６－３０ Preferably, R is one selected from the group consisting of aromatic hydrocarbon groups. ３ As for C １－３０ Alkyl group and —SiR ４ ３ Preferably, one selected from the group consisting of groups.

[0093] R ２ are each independently C １－４ represents an alkyl group or a hydrogen atom. ２ C represented by １－４ The alkyl group may be linear or branched, and is preferably a methyl group or an ethyl group. ２ is preferably one or more selected from a methyl group, an ethyl group, and a hydrogen atom.

[0094] n represents an integer of 1 to 3, and is preferably 1 or 2, and more preferably 1. m represents an integer of 1 to 3, and is preferably 2 or 3, and more preferably 3.

[0095] In one embodiment, the silane coupling agent is preferably represented by the following formula (I-1′): １ ｎ -S(OR ２ ) ｍ ...(I-1') [In formula (1'), R １ are each independently -L １ -R ３Ｉ’ represents L １ each independently represents a single bond or a divalent organic group; R ３Ｉ’ are each independently C １－３０ Alkyl group and C ２－３０ R represents one selected from the group consisting of alkenyl groups; ４ are each independently C １－６ represents a hydrocarbon group, R ２ are each independently C １－４ represents an alkyl group or a hydrogen atom, n represents an integer of 1 to 3, and m represents an integer of 1 to 3.

[0096] In another embodiment, the silane coupling agent is preferably a compound represented by the following formula (I-1″): １ ｎ -S(OR ２ ) ｍ ...(I-1'') [In formula (1''), R １ are each independently -L １ -R ３Ｉ’’ represents L １ each independently represents a single bond or a divalent organic group; R ３Ｉ’’ are each independently C ２－３０ Alkenyl group and C ６－３０ R represents one selected from the group consisting of aromatic hydrocarbon groups; ４ are each independently C １－６ represents a hydrocarbon group, R ２ are each independently C １－４ represents an alkyl group or a hydrogen atom, n represents an integer of 1 to 3, and m represents an integer of 1 to 3.

[0097] In yet another embodiment, the silane coupling agent is preferably a compound represented by the following formula (II-1′): １ ｎ -Si-(OR ２ ) ｍ ...(II-1') [In formula (1'), R １ are each independently -L １ -R ３ＩＩ’ represents L １ each independently represents a single bond or a divalent organic group; R ３ＩＩ’ are each independently C １－３０ Alkyl group and —SiR ４ ３ R represents one selected from the group consisting of ４ are each independently C １－６ represents a hydrocarbon group, R ２ are each independently C １－４ represents an alkyl group or a hydrogen atom, n represents an integer of 1 to 3, and m represents an integer of 1 to 3.

[0098] In another embodiment, the silane coupling agent is preferably a compound represented by the following formula (II-1″): １ ｎ -Si-(OR ２ ) ｍ ...(II-1'') [In formula (1''), R １ are each independently -L １ -R ３ＩＩ’’ represents L １ each independently represents a single bond or a divalent organic group; R ３ＩＩ’’ are each independently C ２－３０ Alkenyl group and C ６－３０ R represents one selected from the group consisting of aromatic hydrocarbon groups; ４ are each independently C １－６ represents a hydrocarbon group, R ２ are each independently C １－４ represents an alkyl group or a hydrogen atom, n represents an integer of 1 to 3, and m represents an integer of 1 to 3.

[0099] As the silane coupling agent, a commercially available product or a synthetic product may be used.

[0100] In the surface treatment agent, the content of the compound represented by formula (1) may be preferably 80% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, and even more preferably 95% by mass or more and 100% by mass or less, based on 100% by mass of the silane coupling agent.

[0101] In the above surface treatment agent, the content of the silane coupling agent may be preferably 80% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, and even more preferably 95% by mass or more and 100% by mass or less, based on 100% by mass of the surface treatment agent.

[0102] The surface treatment agent may contain, in addition to the silane coupling agent, water, a catalyst, etc. The catalyst may be either an acid catalyst or a base catalyst, and examples of the acid catalyst include nitric acid, sulfuric acid, and acetic acid, while examples of the base catalyst include ammonia.

[0103] In aspect I, the magnesium oxide is represented by the following formula (2): [In formula (2), n ｓ represents the amount of the silane coupling agent (mol), and N Ａ is Avogadro's number (mol －１ ) and S ｓ is the area occupied by one molecule of the silane coupling agent (m ２ ), m ｍ represents the amount of magnesium oxide added (g), and s ｍ is the specific surface area of ​​magnesium oxide (m ２ ・g －１ ) represents the value r ｓ is preferably 100% or more and 4,000% or less.

[0104] In aspect I, the above r ｓ is preferably 100% or more and 4,000% or less, more preferably 100% or more and 3,500% or less, and even more preferably 100% or more and 3,000% or less. ｓ is preferably 100% or more, and is preferably 4,000% or less, more preferably 3,500% or less, and even more preferably 3,000% or less. ｓ When the lower limit of r is within the above range, it is expected that the probability of contact between the surface treatment agent and the magnesium oxide surface is increased, and the surface treatment reaction is promoted. ｓ When the upper limit of is within the above range, the amount of silane coupling agent added becomes appropriate relative to the surface area of ​​magnesium oxide, which makes it possible to reduce production costs, and it is expected that the thermal conductivity can be maintained even when mixed with a resin, and further that bleed-out can also be suppressed.

[0105] In aspect II, the r ｓ is preferably 40% or more and 500% or less, more preferably 40% or more and 400% or less, and even more preferably 40% or more and 300% or less. ｓ is preferably 40% or more, and is preferably 500% or less, more preferably 400% or less, and even more preferably 300 or less. ｓWhen the lower limit of r is within the above range, it is expected that the probability of contact between the surface treatment agent and the magnesium oxide surface is increased, and the surface treatment reaction is promoted. ｓ When the upper limit of is within the above range, the amount of silane coupling agent added becomes appropriate relative to the surface area of ​​magnesium oxide, which makes it possible to reduce production costs, and it is expected that the thermal conductivity can be maintained even when mixed with a resin, and further that bleed-out can also be suppressed.

[0106] The above r ｓ is preferably 40% or more and 210% or less, more preferably 50% or more and 200% or less, and even more preferably 70% or more and 150% or less. ｓ is preferably 40% or more, more preferably 50% or more, and even more preferably 70% or more, and is preferably 210% or less, more preferably 200% or less, and even more preferably 150% or less.

[0107] The above r ｓ r can also be said to be the ratio of the area that can be covered by the entire amount of the silane coupling agent to the surface area of ​​the MgO to be surface treated. ｓ When the lower limit of r is in the above range, the coverage of MgO with the silane coupling agent can be increased. ｓ When the upper limit of is within the above range, it is easy to increase the coating efficiency with the silane coupling agent.

[0108] The area occupied by one molecule of the silane coupling agent can be calculated based on the area occupied by the SO- group bonded to MgO, and is, for example, 13 × 10 －２０ (m ２ ) can be used.

[0109] The magnesium oxide having the surface treatment layer can be produced by a wet process.

[0110] Specifically, the technical scope of the present disclosure also includes a method for producing magnesium oxide, which comprises surface-treating a first magnesium oxide with a surface treatment agent containing a silane coupling agent to obtain a second magnesium oxide having a surface treatment layer, wherein the surface treatment is carried out by a wet process.

[0111] It is believed that by carrying out the above surface treatment by wet processing, the silane coupling agent can be uniformly attached to the MgO surface.

[0112] In the present disclosure, the term "wet treatment" refers to a treatment in which a mixture containing an object to be surface-treated and a surface treatment agent is in a slurry state. The slurry may be, for example, a mixed liquid having a solid content concentration of 10% by mass or more and 70% by mass or less, preferably 20% by mass or more and 65% by mass or less, and more preferably 30% by mass or more and 60% by mass or less.

[0113] In the present disclosure, the solid content of the mixed liquid means the heating residue after heating the mixed liquid at 105°C for 1 hour, and the solid content concentration means the value obtained by dividing the total mass of the heating residue by the total mass of the mixed liquid subjected to heating.

[0114] The surface treatment agent containing the silane coupling agent has the same meaning as the surface treatment agent used to form the surface treatment layer.

[0115] The first magnesium oxide may typically be magnesium oxide having no surface treatment layer, that is, MgO.

[0116] In embodiment I, the specific surface area of ​​the first magnesium oxide is 0.01 m ２ / g or more 1.3m ２ / g, preferably less than 0.05m ２ / g or more 1m ２ / g or less, more preferably 0.1m ２ / g or more 1.0m ２ The specific surface area of ​​the first magnesium oxide may be 0.01 m / g or less. ２ / g or more, preferably 0.05m ２ / g or more, more preferably 0.1 m ２ / g or more, and 1.3m ２ / g, preferably less than 1 m ２ / g or less, more preferably 1.0m ２When the specific surface area of ​​the first magnesium oxide is in the above range, it is easy to control the interface between the magnesium oxide particles having the surface treatment layer formed thereon and the resin, and the viscosity of the mixture when mixed with the resin can be reduced. In Aspect II, the specific surface area of ​​the first magnesium oxide is preferably 0.01 m ２ / g or more 10m ２ / g or less, more preferably 0.05m ２ / g or more 5.0m ２ / g or less, more preferably 0.1m ２ / g or more 3.0m ２ The specific surface area of ​​the first magnesium oxide is preferably 0.01 m / g or less. ２ / g or more, more preferably 0.05m ２ / g or more, more preferably 0.1m ２ / g or more, preferably 10m ２ / g or less, more preferably 5.0m ２ / g or less, more preferably 3.0m ２ / g or less.

[0117] The specific surface area of ​​the first magnesium oxide is preferably 0.01 m ２ / g or more 10m ２ / g or less, more preferably 0.05m ２ / g or more 5.0m ２ / g or less, more preferably 0.1m ２ / g or more 3.0m ２ The specific surface area of ​​the first magnesium oxide is preferably 0.01 m / g or less. ２ / g or more, more preferably 0.05m ２ / g or more, more preferably 0.1m ２ / g or more, preferably 10m ２ / g or less, more preferably 5.0m ２ / g or less, more preferably 3.0m ２ / g or less.

[0118] In Aspect I, the average particle size of the first magnesium oxide may be preferably 0.5 μm or more and 50 μm or less, more preferably 1.0 μm or more and 40 μm or less, and even more preferably 1.5 μm or more and 35 μm or less. The average particle size of the first magnesium oxide may be preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 1.5 μm or more, and may be preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 35 μm or less. Since the average particle size of the first magnesium oxide is within the above range, it is easy to control the surface condition of the magnesium oxide, the obtained magnesium oxide particles having a surface-treated layer may have good moisture resistance, and when the magnesium oxide is mixed with a resin, the viscosity and torque may be low.

[0119] In Aspect II, the average particle size of the first magnesium oxide may be preferably 0.5 μm or more and 10 μm or less, more preferably 1.0 μm or more and 8 μm or less, and even more preferably 1.5 μm or more and 5 μm or less. The average particle size of the first magnesium oxide may be preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 1.5 μm or more, and preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 5 μm or less.

[0120] The average particle size of the first magnesium oxide is preferably 0.5 μm or more and 50 μm or less, more preferably 1.0 μm or more and 40 μm or less, and even more preferably 1.5 μm or more and 30 μm or less. The average particle size of the first magnesium oxide is preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 1.5 μm or more, and is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less.

[0121] The surface treatment agent is a compound represented by the formula (2) ｓ However, it can be used in an amount of preferably 40% or more and 210% or less, more preferably 50% or more and 200% or less, and even more preferably 70% or more and 150% or less.

[0122] In a preferred embodiment, the production method may include: mixing an organic solvent with a first magnesium oxide to obtain a first mixed liquid; mixing a surface treatment agent including a silane coupling agent with the first mixed liquid to obtain a second mixed liquid; removing the organic solvent from the second mixed liquid to obtain a precursor of the second magnesium oxide; and heating and / or drying the precursor of the second magnesium oxide to obtain the second magnesium oxide having a surface treatment layer.

[0123] The organic solvent is preferably one that is miscible with or capable of dissolving the silane coupling agent.

[0124] The boiling point of the organic solvent may be preferably 70° C. or higher and 140° C. or lower, more preferably 75° C. or higher and 130° C. or lower, and even more preferably 80° C. or higher and 120° C. When the boiling point of the organic solvent is within this range, the stability of the surface treatment is good, and subsequent heating and / or drying of the precursor may be easy.

[0125] The organic solvent is preferably an alcohol solvent, and specific examples thereof include ethanol, isopropyl alcohol, and butanol.

[0126] In the first mixed liquid, the amount of the organic solvent may be preferably 50 parts by mass or more and 900 parts by mass or less, more preferably 60 parts by mass or more and 400 parts by mass or less, and even more preferably 70 parts by mass or more and 200 parts by mass or less, relative to 100 parts by mass of the first magnesium oxide.

[0127] The first mixed solution may further contain water. The amount of water may be preferably from 0 to 10 parts by mass, more preferably from 0.01 to 5 parts by mass, and even more preferably from 0.05 to 3 parts by mass, relative to 100 parts by mass of the organic solvent contained in the first mixed solution.

[0128] When the first mixed solution contains water, the order of mixing the organic solvent, the first magnesium oxide, and the water is not particularly limited. For example, the organic solvent and water may be mixed together, and then the mixture may be further mixed with magnesium oxide; the organic solvent and magnesium oxide may be mixed together, and then the mixture may be further mixed with water; or the organic solvent, water, and magnesium oxide may be mixed simultaneously. The mixing of the organic solvent and the first magnesium oxide may be performed, for example, by stirring and / or ultrasonic treatment. The stirring may be performed using a magnetic stirrer and a mechanical stirrer. The use of a magnetic stirrer makes it easy to control the stirring, and the use of a mechanical stirrer allows for uniform mixing even when the mixed solution has a high viscosity. When performing the stirring, a baffle plate may be attached to the stirring tank. The attachment of a baffle plate can improve stirring efficiency. The ultrasonic treatment can break down agglomerates of the first magnesium oxide, resulting in a more uniform mixed solution.

[0129] The preparation of the first mixed liquid can be carried out under conditions in which the temperature of the first mixed liquid is preferably 10°C or higher and 40°C or lower, more preferably 15°C or higher and 30°C or lower.

[0130] The surface treatment agent containing the silane coupling agent has the same meaning as the surface treatment agent used to form the surface treatment layer.

[0131] In the embodiment I, the surface treatment agent is a compound represented by the formula (2) ｓ is preferably 100% or more and 4,000% or less, more preferably 100% or more and 3,500% or less, and even more preferably 100% or more and 3,000% or less. ｓ is preferably 100% or more, and is preferably 4,000% or less, more preferably 3,500% or less, and further preferably 3,000% or less. ｓ When the lower limit of r is within the above range, it is expected that the probability of contact between the surface treatment agent and the magnesium oxide surface is increased, and the surface treatment reaction is promoted. ｓWhen the upper limit of is within the above range, the amount of silane coupling agent added becomes appropriate relative to the surface area of ​​magnesium oxide, which makes it possible to reduce production costs, and it is expected that the thermal conductivity can be maintained even when mixed with a resin, and further that bleed-out can also be suppressed.

[0132] In aspect II, the surface treatment agent is a compound represented by the formula (2) ｓ is preferably 100% or more and 500% or less, more preferably 100% or more and 400% or less, and even more preferably 100% or more and 300% or less. ｓ is preferably 100% or more, and is preferably 500% or less, more preferably 400% or less, and even more preferably 300% or less. ｓ When the lower limit of r is within the above range, it is expected that the probability of contact between the surface treatment agent and the magnesium oxide surface is increased, and the surface treatment reaction is promoted. ｓ When the upper limit of is within the above range, the amount of silane coupling agent added becomes appropriate relative to the surface area of ​​magnesium oxide, which makes it possible to reduce production costs, and is also expected to maintain thermal conductivity even when mixed with a resin, and to suppress bleed-out.

[0133] The surface treatment agent is a compound represented by the formula (2) ｓ However, it can be used in an amount of preferably 40% or more and 210% or less, more preferably 50% or more and 200% or less, and even more preferably 70% or more and 150% or less.

[0134] The first solution may be allowed to stand for a certain period of time before mixing the surface treatment agent with the first mixed solution, which is believed to facilitate more uniform mixing of the organic solvent and the first magnesium oxide.

[0135] The mixing of the surface treatment agent with the first mixed solution can be carried out by the stirring treatment and / or ultrasonic treatment. By carrying out the mixing by the stirring treatment and / or ultrasonic treatment, it is believed that more uniform mixing is possible, and a more uniform surface treatment layer can be formed in the obtained second magnesium oxide.

[0136] The second mixed liquid may be prepared at a temperature at which the temperature of the second mixed liquid is equal to or higher than the melting point of the silane coupling agent and equal to or lower than the boiling point of the organic solvent, and specifically, may be prepared under conditions where the temperature is preferably 10° C. or higher and 40° C. or lower, and more preferably 15° C. or higher and 30° C. or lower. It is believed that mixing the surface treatment agent and the first mixed liquid at such a temperature enables more uniform stirring, and enables the formation of a more uniform surface treatment layer in the resulting second magnesium oxide.

[0137] Methods for removing the organic solvent from the second mixed liquid include, for example, filtration, evaporation, centrifugation, and freeze-drying. Filtration allows for efficient removal of the organic solvent. Evaporation can easily remove only the organic solvent. Centrifugation has a high separation power between solids and liquids, making it easy to remove the organic solvent even when the viscosity of the second mixed liquid is high. Freeze-drying makes it easy to suppress aggregation of magnesium oxide.

[0138] The temperature for heating and / or drying the obtained second magnesium oxide precursor is not particularly limited, as long as it can evaporate the solvent and is below the decomposition temperature of the silane coupling agent. The temperature for heating and / or drying the second magnesium oxide precursor is preferably 80°C or higher and 250°C or lower, more preferably 100°C or higher and 220°C or lower, and even more preferably 120°C or higher and 200°C or lower. The time for heating and / or drying the second magnesium oxide precursor is preferably 30 minutes or higher and 48 hours or lower, more preferably 1 hour or higher and 24 hours or lower. By heating and / or drying the precursor under such conditions, the reaction between the silane coupling agent and magnesium oxide progresses, and a surface treatment layer can be formed.

[0139] The heating and / or drying can be carried out using, for example, a hot air dryer, a microwave dryer, or a rotary dryer. A hot air dryer is highly versatile and can perform heating and drying with high efficiency. A rotary dryer is suitable for heating and drying a large amount of precursor with high efficiency. A microwave dryer does not require a high-temperature heat source, so energy consumption can be easily reduced.

[0140] The magnesium oxide of the present disclosure may be produced by a method different from the production method in the above-described embodiment, and the method for producing magnesium oxide of the present disclosure is not limited to only those that provide the magnesium oxide described above.

[0141] The magnesium oxide can be preferably used as a thermally conductive material, particularly as a heat-dissipating filler. The heat-dissipating filler is mixed with a resin material, a rubber material, or the like to form a heat-dissipating member. Examples of the resin material include thermoplastic resins such as polyolefin resins, polyamide resins, and polyphenylene sulfide resins, and thermosetting resins such as epoxy resins, phenolic resins, silicone resins, urea resins, melamine resins, and unsaturated polyesters. Examples of the rubber material include silicone rubber, butyl rubber, butadiene rubber, acrylic rubber, ethylene propylene rubber, urethane rubber, and urethane rubber silicone resin.

[0142] In a composition containing magnesium oxide and a resin material and / or a rubber material, the volume ratio of magnesium oxide to the total of the resin material and / or rubber material and magnesium oxide (magnesium oxide / (resin material and / or rubber material + magnesium oxide)) may be preferably 1 or more and 90 or less, more preferably 5 or more and 60 or less, and even more preferably 10 or more and 50 or less.

[0143] In Aspect I, the composition has a torque measured by the following method of preferably 50 N m or less, more preferably 45 N m or less, even more preferably 40 N m or less, and may be, for example, 10 N m or more, 15 Pa s or more, or even 20 N m or more. In Aspect II, the composition has a torque measured by the following method of preferably 53 N m or less, more preferably 50 N m or less, even more preferably 45 N m or less, or even more preferably 40 N m or less, and may be, for example, 10 N m or more, 15 Pa s or more, or even 20 N m or more. [Method for measuring torque] An ethylene-octene polyolefin resin is heated to 120°C and kneaded for 10 minutes, and then magnesium oxide is added to the ethylene-octene polyolefin resin so that the volume ratio of the ethylene-octene polyolefin resin to the magnesium oxide becomes 51:49. The mixture is further kneaded at 120°C for 15 minutes, and the torque (N m) is measured at a rotation speed of 30 rpm.

[0144] In Aspect I, the viscosity of the composition, as measured by the following method (i), is preferably 70 Pa s or less, more preferably 67 Pa s or less, and even more preferably 65 Pa s or less, and may be, for example, 10 Pa s or more, 15 Pa s or more, or even 20 Pa s or more. In Aspect II, the viscosity of the composition, as measured by the following method (i), is preferably 130 Pa s or less, more preferably 120 Pa s or less, and even more preferably 110 Pa s or less, and may be, for example, 40 Pa s or more, 50 Pa s or more, or even 60 Pa s or more. [Viscosity Measurement Method (i)] A bisphenol epoxy resin and magnesium oxide are mixed in a volume ratio of 70:30. The mixture is stirred at 25°C for 1 hour at 500 rpm to obtain a resin composition. Using a rheometer, disposable parallel plates with a diameter of 25 mm and disposable cups with a diameter of 80 mm were used, the temperature was 25°C, the gap distance was 1 mm, and the measurement shear rate range was 0 to 20 s －１ The viscosity (Pa·s) is measured under the conditions of 100° C., 100° C., and 20 seconds of measurement time.

[0145] In Aspect I, the viscosity of the composition, as measured by the following method (ii), is preferably 19 Pa s or less, more preferably 18 Pa s or less, even more preferably 17 Pa s or less, and may be, for example, 10 Pa s or more, or even 15 Pa s or more. In Aspect II, the viscosity of the composition, as measured by the following method (ii), is preferably 27 Pa s or less, more preferably 26 Pa s or less, even more preferably 25 Pa s or less, and may be, for example, 10 Pa s or more, 15 Pa s or more, or even 20 Pa s or more. [Viscosity Measurement Method (ii)] A polyfunctional acrylic monomer and magnesium oxide are mixed in a volume ratio of 60:40. The mixture is stirred at 25°C for 1 hour at 500 rpm to obtain a resin composition. Using a rheometer, disposable parallel plates with a diameter of 25 mm and disposable cups with a diameter of 80 mm were used, the temperature was 23°C, the gap distance was 1 mm, and the measurement shear rate range was 0 to 20 s －１ The viscosity (Pa·s) is measured under the conditions of 100° C., 100° C., and 20 seconds of measurement time.

[0146] The polyfunctional acrylic monomer may be any compound having two or more (meth)acryloyl groups in one molecule, and examples thereof include bifunctional (meth)acrylic monomers such as ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate; and trifunctional or higher functional (meth)acrylic monomers such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate. Of these, tri- or higher functional (meth)acrylic monomers are preferred, and pentaerythritol tri(meth)acrylate and pentaerythritol tetra(meth)acrylate are preferred.

[0147] The molecular weight of the polyfunctional acrylic monomer is preferably 150 or more and 800 or less, and more preferably 250 or more and 400 or less.

[0148] The magnesium oxide of the present disclosure can suppress increases in torque and viscosity when mixed with a resin, which is expected to reduce the load on the equipment used to produce the resin composition or heat dissipating material and also improve the moldability of the resin material containing magnesium oxide.

[0149] In such heat dissipating components, the above-mentioned magnesium oxide may be used alone as a heat dissipating filler, or the above-mentioned magnesium oxide may be used in combination with one or more other fillers selected from metal hydroxides, metal oxides, and metal nitrides. The heat dissipating filler and other fillers used in the heat dissipating component may or may not be surface-treated. That is, these heat dissipating fillers and other fillers may or may not have a surface treatment layer. Furthermore, the shape and particle size of the heat dissipating filler and other fillers are not particularly limited. The heat dissipating filler using magnesium oxide of the present disclosure is wet-treated, which not only increases the durability (thermal conductivity retention) of the heat dissipating component, but also makes it easier to mix with resin (reducing viscosity / torque during mixing), allowing for larger amounts to be filled / mixed. As a result, the load on the manufacturing equipment is reduced and thermal conductivity can be increased.

[0150] Examples of the heat dissipation member include TIM materials such as heat dissipation sheets, heat dissipation pads, phase change sheets, heat dissipation tapes, heat dissipation gap fillers, heat dissipation adhesives, heat dissipation greases, and sealants; and heat dissipation substrates such as heat dissipation insulating sheets and ceramic-based circuit boards. Such TIM materials and heat dissipation substrates can be used in devices such as automobiles (particularly inverters, ECUs, LiBs, etc.), mobile devices such as smartphones, communication devices, communication base stations, electrical appliances (particularly inverters, etc.), and LEDs.

[0151] The magnesium oxide can also be used as a filler for compounds. The filler is mixed with resins and other additives to form compounds. Examples of the resins include thermoplastic resins such as polyolefin resins, polyamide resins, and polyphenylene sulfide resins, and thermosetting resins such as epoxy resins, phenolic resins, silicone resins, urea resins, melamine resins, and unsaturated polyesters.

[0152] The present disclosure will be explained in more detail below with reference to examples, but the present disclosure is not limited thereto.

[0153] (Synthesis Example 1: Silane Coupling Agent A) 22.5 parts by weight of 3-isocyanatopropyltriethoxysilane and 45.3 parts by weight of 1-dodecanol (TCI) were placed in a 100 mL eggplant-shaped flask and stirred at 60°C for 6 hours to obtain Silane Coupling Agent A with an alkyl chain at the end. (Molecular weight (MW) 433)

[0154] (Synthesis Example 2: Silane Coupling Agent B) 22.5 parts by weight of 3-isocyanatopropyltriethoxysilane and 45.3 parts by weight of 2-butyloctanol (TCI) were placed in a 100 mL eggplant-shaped flask and stirred at 60°C for 6 hours to obtain Silane Coupling Agent B with an alkyl chain at the end. (Molecular weight (MW) 433)

[0155] (Synthesis Example 3: Silane Coupling Agent C) 10.3 parts by weight of 3-isocyanatopropyltriethoxysilane and 50.0 parts by weight of Silaplane FM-0411 (manufactured by JNC Corporation, OH-terminated dimethylpolysiloxane, Mn 1000) were placed in a 100 mL eggplant-shaped flask and stirred at 60°C for 6 hours to obtain silane coupling agent C with alkyl chains at the terminals. (Weight average molecular weight (Mw) 1247)

[0156] (Synthesis Example 4: Silane Coupling Agent D) 2.6 parts by weight of 3-isocyanatopropyltriethoxysilane and 50.0 parts by weight of Silaplane FM-0421 (manufactured by JNC Corporation, OH-terminated dimethylpolysiloxane, Mn5000) were placed in a 100 mL eggplant-shaped flask and stirred at 60°C for 6 hours to obtain silane coupling agent D with alkyl chains at the terminals. (Weight average molecular weight (Mw): 5247)

[0157] (Example I-1) 400 parts by weight of isopropanol and 200 parts by weight of magnesium oxide (B) were added to a 1 L eggplant-shaped flask and stirred at 30°C and 800 rpm for 1 hour. While continuing to stir, 0.3 parts by weight of silane coupling agent A was added and stirred under the same conditions for another 1 hour. After stirring, the isopropanol was removed to obtain magnesium oxide whose surface was covered with the silane coupling agent. The obtained magnesium oxide was heated in a dryer at 120°C for 6 hours to promote a curing reaction, and magnesium oxide with a completely coated surface was produced by a wet method. (r ｓ: 136%, particle size (D50) of surface-treated magnesium oxide: 24.1 μm, specific surface area of ​​surface-treated magnesium oxide: 0.2 m ２ / g)

[0158] (Examples I-2 to I-8, Comparative Examples I-3 and I-5) Magnesium oxides with the compositions shown in Tables 1 and 2, each having a surface coating completed by a wet method, were prepared through the same steps as in Example I-1. In Tables 1 and 2, magnesium oxide (A) had a specific surface area of ​​1.6 m ２ / g, and the average particle size is 2.5 μm. Magnesium oxide (B) has a specific surface area of ​​0.2 m ２ / g, represents magnesium oxide having an average particle size of 25 μm. IPA represents isopropyl alcohol. Silane coupling agent E represents dodecyltriethoxysilane, silane coupling agent F represents octadecyltriethoxysilane, silane coupling agent G represents vinyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBE-1003), silane coupling agent H represents 3-methacryloxypropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBE-503), silane coupling agent I represents decyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-3103C), silane coupling agent J represents N-phenyl-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-573), and silane coupling agent K represents 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403).

[0159] Comparative Examples I-1 and I-2 Magnesium oxide without surface treatment was used.

[0160] (Comparative Example I-4) 200 parts by weight of magnesium oxide (B) was placed in a Henschel mixer, and while stirring, 0.2 parts by weight of silane coupling agent I was gradually added. After the addition was completed, the mixture was heated at 150°C for 30 minutes, and magnesium oxide with a completely surface-coated surface was obtained by a dry method.

[0161] The magnesium oxides obtained in the Examples and Comparative Examples of Aspect I were evaluated by the following methods.

[0162] (Particle size measurement) Measurement was performed using a laser diffraction / scattering particle size distribution analyzer MT3300EXII manufactured by Microtrac Bell Co., Ltd. Ethanol was used as the solvent. As a pretreatment before measurement, ethanol and the measurement sample were mixed, and the sample was dispersed in ethanol by ultrasonic treatment.

[0163] (Measurement of specific surface area) Measurement was carried out using a specific surface area and pore distribution measuring device BELsorp-max manufactured by Microtrac BEL Corporation.

[0164] (Dyne Value) Wetting tension test mixtures No. 25.4, No. 30.0, No. 35.0, No. 40.0, No. 45.0, and No. 50.0 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and water were prepared as solutions with known dyne values. 0.01 parts by weight of magnesium oxide prepared in the Examples and Comparative Examples was added to 2 mL of each solution adjusted to 25°C, and the lowest dyne value at which all of the added particles floated to the surface of the solution was taken as the dyne value of the surface-coated magnesium oxide.

[0165] (Moisture resistance test) 3.0 g of a sample was placed in a weighing bottle and left in a thermo-hygrostat at a temperature of 85°C and a humidity of 85% for one week, after which the weight change before and after the test was measured. In order to compare particles with different particle sizes and specific surface areas side by side, the value obtained by dividing the weight change rate by the specific surface area was also recorded.

[0166]

[0167]

[0168] Examples I-1 to I-8 are examples of Aspect 1, and it was confirmed that they had good moisture resistance. Comparative Examples I-1 to I-2 and I-4 to I-5 were all examples in which the dyne value was 45 mN / m or more, and the moisture resistance was not fully satisfactory. Comparative Examples I-1 and I-3 were examples in which the specific surface area was 1.3 m ２ / g or more, and the moisture resistance was not fully satisfactory.

[0169] Example I-9 24 parts by weight of ENGAGE 8200 (manufactured by DOW, ethylene-octene polyolefin resin, MFR: 5 g / 10 min, Mooney viscosity (121°C): 8 MU, glass transition temperature: -53°C) was added to a Branbender Plasticorder, heated to 120°C, and kneaded for 10 minutes to soften the resin. 96 parts by weight of the magnesium oxide obtained in Example 3 was added to the softened resin, and kneaded for 15 minutes to prepare a resin composition in which MgO was dispersed. The torque after kneading for 15 minutes was recorded as the torque of the resin composition.

[0170] (Example I-10, Comparative Examples I-6 and I-7) Resin compositions were obtained and the torque was measured in the same manner as in Example 9, except that the magnesium oxide shown in Table 3 was used instead of the magnesium oxide obtained in Example 3.

[0171]

[0172] Examples I-9 and I-10 are examples of mode I, and the torque of the mixture mixed with the resin was suppressed. Comparative Example I-6 is a magnesium oxide having a dyne value of more than 50 mN / m and a specific surface area of ​​1.3 m ２ Comparative Example I-7 is an example in which the dyne value of magnesium oxide exceeds 50 mN / m, and the torque of the mixture mixed with resin was not sufficiently suppressed.

[0173] Example I-11 25 parts by weight of jER-828 (manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin, viscosity at 25°C: 12 to 15 Pa s, epoxy equivalent: 184 to 194 g / eq) and 33 parts by weight of the magnesium oxide prepared in Example 3 were placed in a 50 mL glass bottle and stirred at 25°C and 500 rpm for 1 hour, to obtain a resin composition in which magnesium oxide was dispersed.

[0174] The viscosity of the obtained resin composition was measured. That is, a rheometer (MCR series) manufactured by Anton Paar Japan was equipped with a Φ25 mm disposable parallel plate and a Φ80 mm disposable cup, and the viscosity was measured under the following conditions. －１The viscosity of the mixture was evaluated. Measurement conditions: Measurement mode: Continuous ramp measurement Temperature: 25°C Gap distance: 1 mm Measurement shear rate range: 0 to 20 s －１ Measurement time: 20 s

[0175] (Example I-12, Comparative Examples I-8 to I-10) Resin compositions were obtained in the same manner as in Example 11, except that in Example I-11, the magnesium oxide shown in Table 4 was used instead of the magnesium oxide obtained in Example I-3. Viscosity measurements were carried out on the obtained resin compositions under the same conditions as in Example 11.

[0176]

[0177] Examples I-11 and I-12 are examples of Aspect 1, and the viscosity was suppressed when mixed with a resin. Comparative Example I-8 was a magnesium oxide having a dyne value of 50 mN / m or more and a specific surface area of ​​1.3 m ２ / g or more, and the viscosity of the mixture mixed with the resin was not sufficiently suppressed. Comparative Example I-9 is an example in which the dyne value of magnesium oxide is 50 mN / m or more, and the viscosity of the mixture mixed with the resin was not sufficiently suppressed. Comparative Example I-10 is an example in which the specific surface area is 1.3 m ２ / g or more, and the viscosity of the mixture mixed with the resin was not sufficiently suppressed.

[0178] Example I-13: 10 parts by weight of Aronix M-306 (manufactured by Toa Gosei, polyfunctional acrylic monomer, viscosity at 25°C: 0.45 to 0.75 Pa s) as a polyfunctional acrylic monomer and 20.3 parts by weight of the magnesium oxide prepared in Example 3 were placed in a 50 mL glass bottle and stirred at 25°C and 500 rpm for 1 hour to obtain a resin composition in which magnesium oxide was dispersed. The volume ratio of polyfunctional acrylic monomer to magnesium oxide was 60:40.

[0179] The viscosity of the obtained resin composition was measured. That is, a rheometer (MCR series) manufactured by Anton Paar Japan was equipped with a Φ25 mm disposable parallel plate and a Φ80 mm disposable cup, and the viscosity was measured under the following conditions. －１The viscosity of the mixture was evaluated. Measurement conditions: Measurement mode: Continuous ramp measurement Temperature: 23°C Gap distance: 1 mm Measurement shear rate range: 0 to 20 s －１ Measurement time: 20 s

[0180] (Example I-12, Comparative Examples I-8 to I-10) Resin compositions were obtained in the same manner as in Example I-11, except that the magnesium oxide obtained in Example I-3 was replaced with the magnesium oxide shown in Table 5. Viscosity measurements were carried out on the obtained resin compositions under the same conditions as in Example I-11.

[0181]

[0182] Examples I-13, I-14, and I-15 are examples of mode I, and the viscosity was suppressed when mixed with a resin. Comparative Example I-11 was a magnesium oxide having a dyne value of 50 mN / m or more and a specific surface area of ​​1.3 m ２ / g or more, and the viscosity of the mixture mixed with the resin was not sufficiently suppressed. Comparative Example I-12 is an example in which the dyne value of magnesium oxide is 50 mN / m or more, and the viscosity of the mixture mixed with the resin was not sufficiently suppressed. Comparative Example I-13 is an example in which the specific surface area is 1.3 m ２ / g or more, and the viscosity of the mixture mixed with the resin was not sufficiently suppressed.

[0183] (Examples II-1 to II-15, Comparative Examples II-2 and II-7) Magnesium oxides with the compositions shown in Tables 6 and 7, each having a surface coating completed by a wet method, were prepared through the same steps as in Example I-1. In Tables 6 and 7, magnesium oxide (A) had a specific surface area of ​​1.6 m ２ / g, and represents magnesium oxide having an average particle size of 2.5 μm. IPA represents isopropyl alcohol. In addition, silane coupling agent E represents dodecyltriethoxysilane, silane coupling agent F represents octadecyltriethoxysilane, silane coupling agent G represents vinyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBE-1003), silane coupling agent H represents 3-methacryloxypropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBE-503), silane coupling agent I represents decyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-3103C), silane coupling agent J represents N-phenyl-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-573), and silane coupling agent K represents 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403).

[0184] Comparative Example II-1 Magnesium oxide without surface treatment was used.

[0185] (Comparative Example II-3) 200 parts by weight of magnesium oxide (A) was placed in a Henschel mixer, and 1.8 parts by weight of silane coupling agent A was gradually added while stirring. After the addition was completed, the mixture was heated at 150°C for 30 minutes to obtain magnesium oxide with a completely surface-coated surface by a dry method.

[0186] Comparative Examples II-4 to II-6 Magnesium oxide particles having the compositions shown in Table 7 were prepared by the same process as in Comparative Example II-3 and the surface coating was completed by a dry method.

[0187] The magnesium oxides obtained in the examples and comparative examples were evaluated by the following methods.

[0188] (Particle size measurement) Measurement was performed using a laser diffraction / scattering particle size distribution analyzer MT3300EXII manufactured by Microtrac Bell Co., Ltd. Ethanol was used as the solvent. As a pretreatment before measurement, ethanol and the measurement sample were mixed, and the sample was dispersed in ethanol by ultrasonic treatment.

[0189] (Measurement of specific surface area) Measurement was carried out using a specific surface area and pore distribution measuring device BELsorp-max manufactured by Microtrac BEL Corporation.

[0190] (Dyne Value) Wetting tension test mixtures No. 25.4, No. 30.0, No. 35.0, No. 40.0, No. 45.0, and No. 50.0 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and water were prepared as solutions with known dyne values. 0.01 parts by weight of magnesium oxide prepared in the Examples and Comparative Examples was added to 2 mL of each solution adjusted to 25°C, and the lowest dyne value at which all of the added particles floated to the surface of the solution was taken as the dyne value of the surface-coated magnesium oxide.

[0191] (Moisture resistance test) 3.0 g of a sample was placed in a weighing bottle and left in a thermo-hygrostat at a temperature of 85°C and a humidity of 85% for one week, after which the weight change before and after the test was measured. In order to compare particles with different particle sizes and specific surface areas side by side, the value obtained by dividing the weight change rate by the specific surface area was also recorded.

[0192]

[0193]

[0194] Examples II-1 to II-16 are examples of Aspect II, and were confirmed to have good moisture resistance. Comparative Examples II-1 to II-7 were all examples with dyne values ​​of 45 mN / m or more, and were not fully satisfactory in moisture resistance.

[0195] Example II-17 24 parts by weight of ENGAGE 8200 (manufactured by DOW, ethylene-octene polyolefin resin, MFR: 5 g / 10 min, Mooney viscosity (121°C): 8 MU, glass transition temperature: -53°C) was added to a Branbender Plasticorder, heated to 120°C, and kneaded for 10 minutes to soften the resin. 96 parts by weight of the magnesium oxide obtained in Example II-1 was added to the softened resin, and kneaded for 15 minutes to prepare a resin composition in which MgO was dispersed. The torque after kneading for 15 minutes was recorded as the torque of the resin composition.

[0196] (Example II-18, Comparative Examples II-8 to II-9) Resin compositions were obtained and the torque was measured in the same manner as in Example 17, except that the magnesium oxide shown in Table 8 was used instead of the magnesium oxide obtained in Example II-1.

[0197]

[0198] Examples II-17 and II-18 are examples of Aspect II, and the torque of the mixture was suppressed when mixed with a resin. Comparative Examples II-8 and II-9 are examples in which the dyne value of the magnesium oxide was 45 mN / m or more, and the torque was not sufficiently suppressed when mixed with a resin.

[0199] Example II-19 To a 50 mL glass bottle, 25 parts by weight of jER-828 (manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin, viscosity at 25°C: 12 to 15 Pa s, epoxy equivalent: 184 to 194 g / eq) and 33 parts by weight of the magnesium oxide prepared in Example II-7 were added, and the mixture was stirred at 25°C and 500 rpm for 1 hour, to obtain a resin composition in which magnesium oxide was dispersed.

[0200] The viscosity of the obtained resin composition was measured. That is, a rheometer (MCR series) manufactured by Anton Paar Japan was equipped with a Φ25 mm disposable parallel plate and a Φ80 mm disposable cup, and the viscosity was measured under the following conditions. －１ The viscosity of the mixture was evaluated. Measurement conditions: Measurement mode: Continuous ramp measurement Temperature: 25°C Gap distance: 1 mm Measurement shear rate range: 0 to 20 s －１ Measurement time: 20 s

[0201] (Examples II-20 to II-21, Comparative Examples II-10 to II-12) Resin compositions were obtained in the same manner as in Example II-19, except that the magnesium oxide shown in Table 9 was used instead of the magnesium oxide obtained in Example II-7. Viscosity measurements were carried out on the obtained resin compositions under the same conditions as in Example II-19.

[0202]

[0203] Examples II-1 to II-21 are examples of Aspect II, and the viscosity was suppressed when mixed with a resin. Comparative Examples II-10 to II-12 are examples in which the dyne value of the magnesium oxide was 45 mN / m or more, and the viscosity of the mixture mixed with a resin was not sufficiently suppressed.

[0204] Example II-22: 10 parts by weight of Aronix M-306 (manufactured by Toa Gosei, polyfunctional acrylic monomer, viscosity at 25°C: 0.45 to 0.75 Pa s) as a polyfunctional acrylic monomer and 20.3 parts by weight of the magnesium oxide prepared in Example II-7 were placed in a 50 mL glass bottle and stirred at 25°C and 500 rpm for 1 hour to obtain a resin composition in which magnesium oxide was dispersed. The volume ratio of polyfunctional acrylic monomer to magnesium oxide was 60:40.

[0205] The viscosity of the obtained resin composition was measured. That is, a rheometer (MCR series) manufactured by Anton Paar Japan was equipped with a Φ25 mm disposable parallel plate and a Φ80 mm disposable cup, and the viscosity was measured under the following conditions. －１ The viscosity of the mixture was evaluated. Measurement conditions: Measurement mode: Continuous ramp measurement Temperature: 23°C Gap distance: 1 mm Measurement shear rate range: 0 to 20 s －１ Measurement time: 20 s

[0206] (Examples II-23 to II-24, Comparative Examples II-13 to II-14) Resin compositions were obtained in the same manner as in Example II-22, except that the magnesium oxide obtained in Example II-7 was replaced with the magnesium oxide shown in Table 10. Viscosity measurements were carried out on the obtained resin compositions under the same conditions as in Example II-22.

[0207]

[0208] Examples II-22 to II-24 are examples of Aspect II, and the viscosity was suppressed when mixed with a resin. Comparative Examples II-10 to II-12 are examples in which the dyne value of the magnesium oxide was 45 mN / m or more, and the viscosity of the mixture mixed with a resin was not sufficiently suppressed.

[0209] The magnesium oxide of the present invention is preferably used as a thermally conductive material, particularly as a thermally conductive filler. The thermally conductive filler is mixed with a resin material, rubber, or the like to form a thermally conductive member. Examples of the thermally conductive member include TIM materials such as thermally conductive sheets, thermally conductive pads, phase change sheets, thermally conductive tapes, thermally conductive gap fillers, thermally conductive adhesives, thermally conductive greases, and sealants; and thermally conductive substrates such as thermally conductive insulating sheets and ceramic-based circuit boards. Such TIM materials and thermally conductive substrates can be used in devices such as automobiles (particularly inverters, ECUs, LiBs, etc.), mobile devices such as smartphones, communication devices, communication base stations, electrical appliances (particularly inverters, etc.), and LEDs.

Claims

1. The dyne value is less than 50 mN / m and the specific surface area is less than 0.01 m ２ / g or more 1.3m ２ / g or less.

2. The magnesium oxide according to claim 1, having an average particle size of 0.5 μm or more and 50 μm or less.

3. The magnesium oxide according to claim 1 or 2, which has a surface treatment layer, and which is formed using a surface treatment agent containing a silane coupling agent.

4. The silane coupling agent is represented by the following formula (1): １ ｎ -S(OR ２ ) ｍ ...(1) [In formula (1), R １ Each independently represents -L １ -R ３ represents １ each independently represents a single bond or a divalent organic group; R ３ are each independently １－３０ Alkyl group, C ２－３０ Alkenyl group, C ６－３０ Aromatic hydrocarbon group and -SiR ４ ３ R represents one selected from the group consisting of ４ are each independently １－６ represents a hydrocarbon group, R ２ are each independently １－４ represents an alkyl group or a hydrogen atom, n represents an integer of 1 to 3, and m represents an integer of 1 to 3. The magnesium oxide according to claim 3, comprising a compound represented by the formula:

5. The following formula (2): [In formula (2), n ｓ represents the amount (mol) of the silane coupling agent, and N Ａ is the Avogadro number (mol －１ ) and S ｓ is the area occupied by one molecule of the silane coupling agent (m ２ ), m ｍ represents the amount of magnesium oxide added (g), and s ｍ is the specific surface area of ​​magnesium oxide (m ２ ・g －１ ) represents the value r ｓ The magnesium oxide according to claim 3 or 4, wherein the content of the magnesium oxide is 100% or more and 4,000% or less.

6. Magnesium oxide having a torque of 50 Nm or less as measured by the following method: [Method of measuring torque] An ethylene-octene polyolefin resin is heated to 120°C and kneaded for 10 minutes, and then magnesium oxide is added to the ethylene-octene polyolefin resin so that the volume ratio of the ethylene-octene polyolefin resin to the magnesium oxide is 51:

49. The mixture is further kneaded at 120°C for 15 minutes, and the torque (Nm) is measured at a rotation speed of 30 rpm.

7. The surface treatment layer has a surface treatment layer, and the surface treatment layer is formed using a surface treatment agent containing a silane coupling agent, and the silane coupling agent is represented by the following formula (1): R １ ｎ -S(OR ２ ) ｍ ...(1) [In formula (1), R １ Each independently represents -L １ -R ３ represents １ each independently represents a single bond or a divalent organic group; R ３ are each independently １－３０ Alkyl group, C ２－３０ Alkenyl group, C ６－３０ Aromatic hydrocarbon group and -SiR ４ ３ R represents one selected from the group consisting of ４ are each independently １－６ represents a hydrocarbon group, R ２ are each independently １－４ represents an alkyl group or a hydrogen atom, n represents an integer of 1 to 3, and m represents an integer of 1 to 3. The magnesium oxide according to claim 6, comprising a compound represented by the formula:

8. Magnesium oxide having a viscosity of 70 Pa·s or less as measured by the following method. [Method of measuring viscosity] Bisphenol type epoxy resin and magnesium oxide are mixed so that the volume ratio is 70:

30. The mixture is stirred at 25°C for 1 hour at a rotation speed of 500 rpm to obtain a resin composition. Using a rheometer, disposable parallel plates with a diameter of 25 mm and a disposable cup with a diameter of 80 mm are used, the temperature is 25°C, the gap distance is 1 mm, and the measurement shear rate range is 0 to 20 s －１ The viscosity (Pa·s) is measured under the conditions of 20 seconds.

9. The surface treatment layer is formed using a surface treatment agent containing a silane coupling agent, and the silane coupling agent is represented by the following formula (1): R １ ｎ -S(OR ２ ) ｍ ...(1) [In formula (1), R １ Each independently represents -L １ -R ３ represents １ each independently represents a single bond or a divalent organic group; R ３ are each independently １－３０ Alkyl group, C ２－３０ Alkenyl group, C ６－３０ Aromatic hydrocarbon group and -SiR ４ ３ R represents one selected from the group consisting of ４ are each independently １－６ represents a hydrocarbon group, R ２ are each independently １－４ represents an alkyl group or a hydrogen atom, n represents an integer of 1 to 3, and m represents an integer of 1 to 3. The magnesium oxide according to claim 8, comprising a compound represented by the formula:

10. Magnesium oxide having a viscosity of 19 Pa·s or less, measured by the following method. [Method of measuring viscosity] A polyfunctional acrylic monomer and magnesium oxide are mixed so that the volume ratio is 60:

40. The mixture is stirred at 25°C for 1 hour at a rotation speed of 500 rpm to obtain a resin composition. Using a rheometer, a disposable parallel plate with a diameter of 25 mm and a disposable cup with a diameter of 80 mm are used, the temperature is 23°C, the gap distance is 1 mm, and the measurement shear rate range is 0 to 20 s. －１ The viscosity (Pa·s) is measured under the conditions of 20 seconds.

11. A surface treatment layer is formed using a surface treatment agent containing a silane coupling agent, and the silane coupling agent is represented by the following formula (1): R １ ｎ -S(OR ２ ) ｍ ...(1) [In formula (1), R １ Each independently represents -L １ -R ３ represents １ each independently represents a single bond or a divalent organic group; R ３ are each independently １－３０ Alkyl group, C ２－３０ Alkenyl group, C ６－３０ Aromatic hydrocarbon group and -SiR ４ ３ R represents one selected from the group consisting of ４ are each independently １－６ represents a hydrocarbon group, R ２ are each independently １－４ represents an alkyl group or a hydrogen atom, n represents an integer of 1 to 3, and m represents an integer of 1 to 3. The magnesium oxide according to claim 10, comprising a compound represented by the formula:

12. A method for producing magnesium oxide, comprising: surface-treating a first magnesium oxide with a surface treatment agent including a silane coupling agent to obtain a second magnesium oxide having a surface treatment layer, wherein the surface treatment is carried out by a wet process.

13. A method for producing magnesium oxide according to claim 12, wherein the surface treatment is carried out by a treatment method including: mixing an organic solvent with a first magnesium oxide to obtain a first mixed liquid; mixing the surface treatment agent with the first mixed liquid to obtain a second mixed liquid; removing the organic solvent from the second mixed liquid to obtain a precursor of a second magnesium oxide; and heating and / or drying the precursor of a second magnesium oxide to obtain a second magnesium oxide having a surface treatment layer.

14. A heat dissipation member comprising the magnesium oxide according to any one of claims 1 to 11.

Images