Magnesium oxide

Abstract

To provide a magnesium oxide having superior humidity resistance.SOLUTION: A magnesium oxide of the present disclosure has a dyne value of less than 45 mN / m.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This disclosure relates to magnesium oxide. [Background technology]

[0002] Magnesium oxide can be used in thermally conductive materials, heat-resistant materials, electrical insulating materials, fillers, optical materials, abrasives, and the like. Patent Document 1 describes a method for producing magnesium oxide, which involves calcining magnesium hydroxide having a predetermined particle size and BET specific surface area at 1100 to 1600°C, and then grinding and classifying it to a secondary particle size of 20 μm or less.

[0003] Patent Document 2 states that (C k H (2k+1) ) n -Si-(OC m H (2m+1) ) (4-n) A thermally conductive filler is described, which is magnesium oxide having a predetermined BET specific surface area and average secondary particle diameter, obtained by surface coating magnesium oxide with a coating agent represented by [k: 6 or more, m: 2 or less, n: 1 to 3] at a rate of 1 to 10% by mass. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-171928 [Patent Document 2] Japanese Patent Publication No. 2011-68757 [Overview of the Initiative] [Problems that the invention aims to solve]

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

Means for Solving the Problems

[0006] The first embodiment of the present disclosure provides magnesium oxide having a dyn value of less than 45 mN / m.

[0007] In the second embodiment of the present disclosure, in the first embodiment, the specific surface area of the magnesium oxide may be 1.3 m 2 / g or more and 10 m 2 / g or less.

[0008] In the third embodiment of the present disclosure, in any one of the first and second embodiments, the average particle diameter of the magnesium oxide may be 0.5 μm or more and 50 μm or less.

[0009] In the 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.

[0010] In the fifth embodiment of the present disclosure, in any one of the fourth embodiments, the silane coupling agent is represented by the following formula (1): R 1 n -Si-(OR 2 ) m ···(1) and may contain a compound represented by the formula. In the above formula (1), R 1 each independently represents -L 1 -R 3 and may represent. In the above formula (1), L 1Each of these can independently represent a single bond or a divalent organic group. R in equation (1) above 3 Each of them is independent of C 1-30 Alkyl alkyl group, C 2-30 Alkenyl group, C 6-30 Aromatic hydrocarbon groups and -SiR 4 It can represent one type selected from a group of three units. R in equation (1) above 4 Each of them is independent of C 1-6 It can represent a hydrocarbon group. R in equation (1) above 2 Each of them is independent of C 1-4 It may represent an alkyl group or a hydrogen atom. In equation (1) above, n can represent an integer between 1 and 3. In equation (1) above, m can represent an integer between 1 and 3.

[0011] In the sixth embodiment of this disclosure, in either the fourth or fifth embodiment, The following equation (2):

number

[0012] A seventh embodiment of this disclosure provides magnesium oxide having a torque of 53 N·m or less, as measured by the following method. Furthermore, in the seventh embodiment of this disclosure, the torque measured by the following method in any one of the first to sixth embodiments may be 53 N·m or less. [Method for measuring torque] Ethylene-octene polyolefin resin is heated to 120°C and kneaded for 10 minutes. Then, magnesium oxide is added to the ethylene-octene polyolefin resin so that the volume ratio of the ethylene-octene polyolefin resin to magnesium oxide is 51:49. The mixture is then kneaded again at 120°C for 15 minutes, and the torque (N·m) is measured at a rotation speed of 30 rpm.

[0013] In the eighth embodiment of this disclosure, the magnesium oxide may have a surface treatment layer in any one of the first to seventh embodiments. The above surface treatment layer can be formed using a surface treatment agent containing a silane coupling agent. The above silane coupling agent is given by the following formula (1): R 1 n -Si-(OR 2 ) m ...(1) It may contain compounds represented by [formula]. R in equation (1) above 1 These are, independently, -L 1 -R 3 It can represent this. L in equation (1) above 1 Each of these can independently represent a single bond or a divalent organic group. R in equation (1) above 3 Each of them is independent of C 1-30 Alkyl alkyl group, C 2-30 Alkenyl group, C 6-30 Aromatic hydrocarbon groups and -SiR 4 It can represent one selected from a group consisting of three units, preferably each independently of C 1-30 Alkyl and -SiR 4It can represent one type selected from a group of three units. R in equation (1) above 4 Each of them is independent of C 1-6 It can represent a hydrocarbon group. R in equation (1) above 2 Each of them is independent of C 1-4 It may represent an alkyl group or a hydrogen atom. In equation (1) above, n can represent an integer between 1 and 3. In equation (1) above, m can represent an integer between 1 and 3.

[0014] A ninth embodiment of this disclosure provides magnesium oxide having a viscosity of 130 Pa·s or less, as measured by the following method. Furthermore, in the ninth embodiment of this disclosure, the viscosity measured by the following method in any one of the first to eighth embodiments may be 130 Pa·s or less. [Method for measuring viscosity] A bisphenol-type 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 a rotation speed of 500 rpm to obtain a resin composition. Using a rheometer, a 25 mm diameter disposable parallel plate and an 80 mm diameter disposable cup are used, with a temperature of 25°C, a gap distance of 1 mm, and a measurement shear rate range of 0-20 s. -1 The viscosity (Pa·s) is measured under the condition of a measurement time of 20 seconds.

[0015] In the tenth embodiment of this disclosure, the magnesium oxide may have a surface treatment layer in any one of the first to ninth embodiments. The above surface treatment layer can be formed using a surface treatment agent containing a silane coupling agent. The above silane coupling agent is given by the following formula (1): R 1 n -Si-(OR 2 ) m ...(1) It may contain compounds represented by [formula]. R in equation (1) above 1 These are, independently, -L 1 -R 3 It can represent this. L in equation (1) above 1 Each of these can independently represent a single bond or a divalent organic group. R in equation (1) above 3 Each of them is independent of C 1-30 Alkyl alkyl group, C 2-30 Alkenyl group, C 6-30 Aromatic hydrocarbon groups and -SiR 4 It can represent one selected from a group consisting of three units, preferably C 2-30 Alkenyl group and C 6-30 It can represent one selected from the group consisting of aromatic hydrocarbon groups. R in equation (1) above 4 Each of them is independent of C 1-6 It can represent a hydrocarbon group. R in equation (1) above 2 Each of them is independent of C 1-4 It may represent an alkyl group or a hydrogen atom. In equation (1) above, n can represent an integer between 1 and 3. In equation (1) above, m can represent an integer between 1 and 3.

[0016] An eleventh embodiment of this disclosure provides magnesium oxide having a viscosity of 27 Pa·s or less, as measured by the following method. Furthermore, in the eleventh embodiment of this disclosure, the viscosity measured by the following method in any one of the first to tenth embodiments may be 27 Pa·s or less. [Method for measuring viscosity] 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 a rotation speed of 500 rpm to obtain a resin composition. Using a rheometer, a 25 mm diameter disposable parallel plate and an 80 mm diameter disposable cup are used, at a temperature of 23°C, a gap distance of 1 mm, and a measurement shear rate range of 0-20 s. -1, measure the viscosity (Pa·s) under the condition of a measurement time of 20 seconds.

[0017] In the twelfth embodiment of the present disclosure, in any one of the first to eleventh embodiments described above, 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 has the following formula (1): R 1 n -Si-(OR 2 ) m ···(1) and may contain a compound represented by. In the above formula (1), R 1 may each independently represent -L 1 -R 3 . In the above formula (1), L 1 may each independently represent a single bond or a divalent organic group. In the above formula (1), R 3 may each independently represent a C 1-30 alkyl group, a C 2-30 alkenyl group, a C 6-30 aromatic hydrocarbon group, and a -SiR 4 3 group, and preferably, each independently represents a C 2-30 alkenyl group and a C 6-30 aromatic hydrocarbon group. In the above formula (1), R 4 may each independently represent a C 1-6 hydrocarbon group. In the above formula (1), R 2 may each independently represent a C 1-4 alkyl group or a hydrogen atom. In the above formula (1), n may represent an integer of 1 to 3. In the above formula (1), m may represent an integer of 1 to 3.

[0018] A thirteenth embodiment of the present disclosure includes obtaining a second magnesium oxide having a surface treatment layer by surface treating a first magnesium oxide with a surface treatment agent containing a silane coupling agent, The above surface treatment provides a method for producing magnesium oxide, which is carried out by a wet treatment.

[0019] In the fourteenth embodiment of this disclosure, the surface treatment may be carried out by a treatment method that includes mixing an organic solvent with a first magnesium oxide to obtain a first mixture, as in the thirteenth embodiment. The above processing method may include mixing the surface treatment agent and the first mixed solution to obtain a second mixed solution. The above processing method may include removing the organic solvent from the second mixture to obtain a second magnesium oxide precursor. The above processing method may include heating and / or drying the second magnesium oxide precursor to obtain a second magnesium oxide having a surface treatment layer.

[0020] A fifteenth embodiment of this disclosure provides a heat dissipation member comprising magnesium oxide as described in any one of the first to twelfth embodiments.

[0021] A sixteenth embodiment of this disclosure provides a heat dissipation filler comprising magnesium oxide as described in any one of the first to twelfth embodiments.

[0022] A 17th embodiment of this disclosure provides an apparatus that includes a heat dissipation member as described in any one of the 15th embodiments. [Effects of the Invention]

[0023] The present disclosure may provide magnesium oxide with good moisture resistance. Preferably, the present disclosure may provide low magnesium oxide that can suppress the increase in viscosity of a mixture when mixed with a resin. Also preferably, the present disclosure may provide magnesium oxide that can suppress the increase in torque when stirring a mixture when mixed with a resin. [Modes for carrying out the invention]

[0024] The magnesium oxide of this disclosure has a dyne value of less than 45 mN / m.

[0025] The magnesium oxide of this disclosure has good moisture resistance. In a preferred embodiment, the magnesium oxide of this disclosure exhibits excellent moisture resistance even after long-term use. Therefore, the formation of Mg(OH)2 by the reaction of MgO with water may be suppressed, and acid resistance may also be good. Furthermore, the magnesium oxide of this disclosure may have good affinity with resins and good dispersibility in resins. As a result, the thermal conductivity of resin materials containing the magnesium oxide of this disclosure may be good. This disclosure should not be interpreted as being limited to any particular theory, but the reason why the magnesium oxide of this disclosure may have good moisture resistance is thought to be as follows.

[0026] In other words, the Dyne value is a value that can serve as an indicator of surface free energy; a larger Dyne value indicates higher surface free energy, and a smaller Dyne value indicates lower surface free energy. In the magnesium oxide of this disclosure, it is thought that lowering its surface free energy can suppress interaction with water, thereby improving moisture resistance.

[0027] In this disclosure, "magnesium oxide" is not limited to magnesium oxide as a compound, but may also include materials that have undergone surface treatment or other treatments with magnesium oxide as the main component. In this specification, magnesium oxide as a compound may be written as "MgO". The above magnesium oxide (MgO) as a compound may contain elements such as Ca, Si, Cl, S, Al, and Fe as impurities.

[0028] The dyn value of the magnesium oxide of the present disclosure is less than 45 mN / m, preferably 15 mN / m or more and 40 mN / m or less, and more preferably 20 mN / m or more and 35 mN / m or less. The dyn value of the magnesium oxide of the present disclosure can preferably be 45 mN / m or less, more preferably 40 mN / m or less, still more preferably 35 mN / m or less, and can preferably be 15 mN / m or more, more preferably 20 mN / m or more.

[0029] In the present disclosure, the dyn value of magnesium oxide can be measured by the following method. [Measurement method of dyn value] Prepare solutions with dyn 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. Weigh 2 mL of each liquid into a clean glass container and adjust the liquid temperature to 25°C. As the glass container, use a container with a liquid surface height of 5 mm or more from the inner bottom surface. Next, after drying the measurement sample at 60°C for 1 hour, adjust the temperature of the measurement sample to 25°C. Then, add 0.01 g of the measurement sample onto the surface of each liquid so as to sprinkle it. At the time point when 10 seconds have elapsed after the addition, the lowest dyn value among the dyn values of the liquid in which all the measurement samples float on the liquid surface is taken as the dyn value of the sample.

[0030] In the present disclosure, magnesium oxide can preferably be magnesium oxide particles. In the present disclosure, "particles" represent an aggregate of particulate materials independent of each other. The shape of each particle can be spherical, irregular, etc. When the shape of each particle is spherical, "spherical" is not limited to the case of "true spherical".

[0031] The specific surface area of the magnesium oxide of the present disclosure is preferably 1.3 m 2 / g or more and 10 m 2 / g or less, more preferably 1.3 m 2 / g or more and 5.0 m 2 / g or less, still more preferably 1.3 m 2 / g or more and 3.0 m 2It may be less than or equal to / g. The specific surface area of ​​the magnesium oxide of this disclosure is preferably 1.3 m². 2 / g or more, preferably 10m 2 Less than / g, more preferably 5.0m 2 / g or less, more preferably 3.0m 2 It may be less than / g. Because 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 the resin, and it is easy to suppress increases in viscosity and torque of the mixture when mixed with the resin.

[0032] The specific surface area of ​​the magnesium oxide in this disclosure is preferably 0.01 m². 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 It may be less than or equal to / g. The specific surface area of ​​the magnesium oxide of this disclosure is preferably 0.01 m². 2 / g or more, more preferably 0.05m 2 / g or more, more preferably 0.1m 2 / g or more, preferably 10m 2 Less than / g, more preferably 5.0m 2 / g or less, more preferably 3.0m 2 It may be less than / g.

[0033] In this disclosure, the specific surface area may be measured by the BET method, specifically in accordance with JIS Z 8830.

[0034] The average particle size of the magnesium oxide in this disclosure is 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 in this disclosure is preferably 0.5 μm or more, more preferably 1.0 μm or more, 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.

[0035] The average particle size of the magnesium oxide in this disclosure 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 30 μm or less. The average particle size of the magnesium oxide in this disclosure may be preferably 0.5 μm or more, more preferably 1.0 μm or more, 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 30 μm or less.

[0036] In this disclosure, the average particle diameter may be measured by the microtrac method and may be the volume-based median diameter (D50).

[0037] The magnesium oxide of this disclosure has a specific surface area of ​​1.3 m². 2 / g or more 10m 2 Preferably, the particle size is less than or equal to / g, the average particle diameter is between 0.5 μm and 10 μm, and the specific surface area is 1.3 m². 2 / g or more 5.0m 2 The particle size is less than or equal to / g, more preferably the average particle diameter is between 1.0 μm and 8 μm, and the specific surface area is 1.3 m². 2 / g or more 3.0m 2 It is even more preferable that the particle size is less than or equal to / g and that the average particle diameter is between 1.5 μm and 5 μm.

[0038] The magnesium oxide of this disclosure has a specific surface area of ​​0.01 m². 2 / g or more 10m 2 The particle size is preferably less than or equal to / g, with an average particle diameter of 0.5 μm to 50 μm, and a specific surface area of ​​0.05 m². 2 / g or more 5m 2 The particle size is less than or equal to / g, more preferably the average particle diameter is between 1.0 μm and 40 μm, and the specific surface area is 0.1 m². 2 / g or more 3m 2 It is even more preferable that the particle size is less than or equal to / g and that the average particle diameter is between 1.5 μm and 30 μm.

[0039] The magnesium oxide of this disclosure has a torque, as measured by the following method, preferably 53 N·m or less, more preferably 50 N·m or less, even more preferably 45 N·m or less, and even more preferably 40 N·m or less, and may be, for example, 10 N·m or more, 15 Pa·s or more, and even more preferably 20 N·m or more. [Method for measuring torque] Ethylene-octene polyolefin resin is heated to 120°C and kneaded for 10 minutes. Then, magnesium oxide is added to the ethylene-octene polyolefin resin so that the volume ratio of the ethylene-octene polyolefin resin to magnesium oxide is 51:49. The mixture is then kneaded again at 120°C for 15 minutes, and the torque (N·m) is measured at a rotation speed of 30 rpm.

[0040] In such embodiments, the magnesium oxide of the present disclosure preferably has a surface treatment layer, which is preferably formed using a surface treatment agent containing a silane coupling agent. The silane coupling agent preferably contains a compound represented by formula (1), which will be described later, and more preferably contains a compound represented by formula (1'), which will be described later.

[0041] The magnesium oxide of this disclosure has a viscosity, as measured by the following method (i), 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, and even more preferably 60 Pa·s or more. [Method for measuring viscosity (i)] A bisphenol-type 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 a rotation speed of 500 rpm to obtain a resin composition. Using a rheometer, a 25 mm diameter disposable parallel plate and an 80 mm diameter disposable cup are used, with a temperature of 25°C, a gap distance of 1 mm, and a measurement shear rate range of 0-20 s. -1 The viscosity (Pa·s) is measured under the condition of a measurement time of 20 seconds.

[0042] In such embodiments, the magnesium oxide of the present disclosure preferably has a surface treatment layer, which is preferably formed using a surface treatment agent containing a silane coupling agent. The silane coupling agent preferably contains a compound represented by formula (1), which will be described later, and more preferably contains a compound represented by formula (1''), which will be described later.

[0043] The magnesium oxide of this disclosure has a viscosity, as measured by the following method (ii), 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, and even more preferably 20 Pa·s or more. [Method for measuring viscosity (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 a rotation speed of 500 rpm to obtain a resin composition. Using a rheometer, a 25 mm diameter disposable parallel plate and an 80 mm diameter disposable cup are used, at a temperature of 23°C, a gap distance of 1 mm, and a measurement shear rate range of 0-20 s. -1 The viscosity (Pa·s) is measured under the condition of a measurement time of 20 seconds.

[0044] In such embodiments, the magnesium oxide of the present disclosure preferably has a surface treatment layer, which is preferably formed using a surface treatment agent containing a silane coupling agent. The silane coupling agent preferably contains a compound represented by formula (1), which will be described later, and more preferably contains a compound represented by formula (1''), which will be described later.

[0045] The magnesium oxide of this disclosure can suppress the increase in torque when mixed with a resin. Furthermore, the magnesium of this disclosure can also suppress the increase in viscosity when mixed with a resin. This reduces the load on the equipment during manufacturing, and if the resin material containing magnesium oxide is a liquid, it can be injected into confined spaces by improving its fluidity, and if it is a solid, it is expected to improve its moldability.

[0046] The magnesium oxide of this disclosure preferably has a surface treatment layer on its surface. That is, the magnesium oxide of this disclosure may be a material comprising 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 of the surface of the MgO, and preferably covers all of it.

[0047] The above-mentioned surface treatment layer can preferably be formed using a surface treatment agent containing a silane coupling agent.

[0048] Silane coupling agents can be compounds having a hydrolyzable silyl group and a monovalent organic group. The hydrolyzable silyl group represents a Si atom to which a hydroxyl group or hydrolyzable group is bonded.

[0049] The above hydrolyzable groups refer to groups that can produce a silanol group through hydrolysis. Examples of such hydrolyzable groups include -OR a1 , -OCOR a1 Examples include halogens and hydrogen atoms. a1 C 1-4 It represents an alkyl group, preferably a methyl group or an ethyl group.

[0050] The above monovalent organic group may be a monovalent group containing a carbon atom, a monovalent hydrocarbon group; a monovalent or divalent hydrocarbon group, and -O-, -CO-, -NR a2 - and -SiR a3 It may be a group selected from 2- or a combination of two or more. a2 C 1-4 R represents an alkyl group or a hydrogen atom. a3 C 1-6 This represents a hydrocarbon group. A divalent or more organic group may be a group that uses one or more hydrogen atoms contained in the above monovalent organic group as bonding sites.

[0051] The above monovalent hydrocarbon group is a monovalent group containing carbon and hydrogen, and may be a group that uses one hydrogen atom contained in a hydrocarbon compound as a bonding agent. The above 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 combination of two or more groups selected from aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The aliphatic hydrocarbon group may be linear or branched, and may be saturated or unsaturated. A divalent or higher hydrocarbon group may be a group that uses one or more hydrogen atoms contained in the monovalent hydrocarbon group as a bonding agent.

[0052] The molecular weight of the silane coupling agent is preferably 130 to 10,000, more preferably 140 to 6,000. The higher the molecular weight of the silane coupling agent, the better the water resistance of the resulting magnesium oxide may be. In this disclosure, the molecular weight of silane coupling agents with a molecular weight of less than 500 can be calculated based on the structural formula of the silane coupling agent. Furthermore, the molecular weight of silane coupling agents with a molecular weight of 500 or more refers to the weight-average molecular weight, which can be measured by gel permeation chromatography and calculated as a converted value using polystyrene as the standard sample.

[0053] The above silane coupling agent is preferably of the following formula (1): R 1 n -Si-(OR 2 ) m ...(1) [In formula (1), R 1 These are, independently, -L 1 -R 3 This represents, L 1 Each of these independently represents a single bond or a divalent organic group. R 3 Each of them is independent of C 1-30 Alkyl alkyl group, C 2-30 Alkenyl group, C 6-30Aromatic hydrocarbon groups and -SiR 4 This represents one type selected from a group of three structures. R 4 Each of them is independent of C 1-6 Represents a hydrocarbon group, R 2 Each of them is independent of C 1-4 Represents an alkyl group or a hydrogen atom, n represents an integer between 1 and 3. m represents an integer between 1 and 3. It may contain compounds represented by [formula].

[0054] R 1 These are, independently, -L 1 -R 3 It represents.

[0055] L 1 Each of these independently represents a single bond or a divalent organic group.

[0056] L 1 Divalent organic groups represented by include divalent hydrocarbon groups; divalent hydrocarbon groups and -O-, -CO-, -NR a2 and -SiR a2 Examples include groups selected from 2-, or groups selected from 2- in combination with two or more other groups.

[0057] L 1 Preferably, the following equations (i) to (iv): -R a4 -O-CO- ···(i) -R a4 -NR a2 - ···(ii) -R a4 -NR a2 -CO-O- ···(iii) -R a4 -NR a2 -CO-OR a5 -(OR a6 ) p1 -(OSiR a3 2) p2 - ···(iv) [In formulas (i) to (iv), Ra2 C 1-4 Represents an alkyl group or a hydrogen atom, R a3 C 1-6 Represents a hydrocarbon group, R a4 C 1-4 Represents an alkylene group, R a5 C 1-4 Represents an alkylene group, R a6 C 1-4 Represents an alkylene group, p1 represents an integer from 1 to 5. p2 represents an integer between 2 and 100. It can be represented as follows.

[0058] In equations (i) to (iv), preferably, R a4 One end of the side is bonded to the Si atom in equation (1), and the other end is R 3 It combines with it.

[0059] 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 A hydrogen atom is preferred as the element.

[0060] R a3 C represented by 1-6 As for hydrocarbon groups, C 1-6 Examples include alkyl groups and phenyl groups. 1-6 The alkyl group may be linear or branched, preferably C 1-4 It is an alkyl group, more preferably a methyl group or an ethyl group, and even more preferably a methyl group. a3 A methyl group or a phenyl group is preferred.

[0061] R a4 C represented by 1-4 The alkylene group may be linear or branched, preferably C 2-3 It may be an alkylene group.

[0062] R a5 C represented by 1-4 The alkylene group may be linear or branched, preferably C 2-3 It may be an alkylene group.

[0063] R a6 C represented by 1-4 The alkylene group may be linear or branched, preferably C 2-3 It may be an alkylene group.

[0064] p1 represents an integer between 1 and 5, and is preferably between 1 and 3.

[0065] p2 represents an integer between 2 and 100, preferably between 5 and 80, and more preferably between 10 and 70.

[0066] L 1 Preferably, the group is a single bond or a group represented by formulas (i), (ii), (iii), or (iv), and more preferably a single bond or a group represented by formulas (i), (ii), or (iv).

[0067] R 3 C 1-30 Alkyl alkyl group, C 2-30 Alkenyl group, C 6-30 Aromatic hydrocarbon groups and -SiR 4 This represents one selected from the group consisting of 3, and in one embodiment, preferably C 1-30 Alkyl and -SiR 4 It may be one selected from a group consisting of three units, and in another embodiment, preferably C 2-30 Alkenyl group and C 6-30 It may be one selected from the group consisting of aromatic hydrocarbon groups.

[0068] R 3 C represented by 1-30 The alkyl group may be linear or branched, and is preferably branched. 1-30 The alkyl group is preferably a linear or branched C 1-30An alkyl group, more preferably a linear or branched C 5-25 It is an alkyl group, and more preferably a linear or branched C 10-20 It is an alkyl group, and more preferably a branched C 10-20 It can be an alkyl group.

[0069] R 3 C represented by 2-30 The alkenyl group may be linear or branched. 2-30 The alkenyl group is preferably linear or branched C 2-15 Alkenyl group, more preferably linear or branched C 2-10 The alkenyl group, more preferably a linear or branched C group. 2-7 It is an alkenyl group, and more preferably a linear or branched C group. 2-4 It can be an alkenyl group.

[0070] 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 carbon group. 6-20 Aromatic hydrocarbon group, more preferably monocyclic or polycyclic C 6-15 Aromatic hydrocarbon group, more preferably monocyclic or polycyclic C 6-10 It is an aromatic hydrocarbon group, and more preferably a monocyclic C 6-8 It can be an aromatic hydrocarbon group. 3 Examples of aromatic hydrocarbon groups represented by include phenyl, toluyl, xylyl, styryl, and naphthyl groups.

[0071] R 4 C represented by 1-6 As for hydrocarbon groups, C 1-6 Examples include alkyl groups and phenyl groups. 1-6 The alkyl group may be linear or branched, preferably C 1-4It is an alkyl group, more preferably a methyl group or an ethyl group, and even more preferably a methyl group. 4 A methyl group or a phenyl group is preferred.

[0072] In one embodiment, R 3 C 1-30 Alkyl alkyl group, C 2-30 Alkenyl group and -SiR 4 A choice of one from a group of three units is preferred. In another embodiment, R 3 C 1-30 Alkyl and -SiR 4 A choice of one from a group of three units is preferred. In yet another embodiment, R 3 C 2-30 Alkenyl group and C 6-30 A preferred type is selected from the group consisting of aromatic hydrocarbon groups. In yet another embodiment, R 3 C 2-30 Alkenyl group and C 6-30 A preferred type is selected from the group consisting of aromatic hydrocarbon groups.

[0073] R 2 Each of them is independent of 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 Preferably, it is one or more selected from a methyl group, an ethyl group, and a hydrogen atom.

[0074] n represents an integer between 1 and 3, preferably 1 or 2, and more preferably 1. m represents an integer between 1 and 3, preferably 2 or 3, and more preferably 3.

[0075] In one embodiment, the above silane coupling agent is preferably of the following formula (1'): R 1n -Si-(OR 2 ) m ...(1') [In formula (1'), R 1 These are, independently, -L 1 -R 3’ This represents, L 1 Each of these independently represents a single bond or a divalent organic group. R 3’ Each of them is independent of C 1-30 Alkyl and -SiR 4 This represents one type selected from a group of three structures. R 4 Each of them is independent of C 1-6 Represents a hydrocarbon group, R 2 Each of them is independent of C 1-4 Represents an alkyl group or a hydrogen atom, n represents an integer between 1 and 3. m represents an integer between 1 and 3. It may contain compounds represented by [formula].

[0076] In another embodiment, the silane coupling agent is preferably of the following formula (1''): R 1 n -Si-(OR 2 ) m ...(1'') [In formula (1''), R 1 These are, independently, -L 1 -R 3’’ This represents, L 1 Each of these independently represents a single bond or a divalent organic group. R 3’’ Each of them is independent of C 2-30 Alkenyl group and C 6-30 This represents one selected from the group consisting of aromatic hydrocarbon groups. R 4 Each of them is independent of C 1-6 Represents a hydrocarbon group, R 2Each of them is independent of C 1-4 Represents an alkyl group or a hydrogen atom, n represents an integer between 1 and 3. m represents an integer between 1 and 3. It may contain compounds represented by [formula].

[0077] The silane coupling agent may be a commercially available product or a synthetic product.

[0078] In the above surface treatment agent, the content of the compound represented by formula (1) may be preferably 80% to 100% by mass, more preferably 90% to 100% by mass, and even more preferably 95% to 100% by mass, based on 100% by mass of the silane coupling agent.

[0079] In the above surface treatment agent, the content of the silane coupling agent may be preferably 80% to 100% by mass, more preferably 90% to 100% by mass, and even more preferably 95% to 100% by mass, based on 100% by mass of the surface treatment agent.

[0080] The above surface treatment agent may contain water and a catalyst in addition to the silane coupling agent. The catalyst may be either an acid catalyst or a base catalyst. Examples of acid catalysts include nitric acid, sulfuric acid, and acetic acid, while examples of base catalysts include ammonia.

[0081] In the above magnesium oxide, the following formula (2):

number

[0082] The above r s This may preferably be 40% to 500%, more preferably 40% to 400%, and even more preferably 40% to 300%. s The above r is preferably 40% or more, preferably 500% or less, more preferably 400% or less, and even more preferably 300% or less. s By having the lower limit within the above range, the probability of contact between the surface treatment agent and the magnesium oxide surface is increased, and it is expected that the surface treatment reaction will be promoted. On the other hand, the above r s Because the upper limit is within the above range, the amount of silane coupling agent added will be appropriate relative to the surface area of ​​magnesium oxide, which is expected to reduce manufacturing costs, maintain thermal conductivity even when mixed with resin, and suppress bleed-out.

[0083] The above r s This may preferably be 40% to 210%, more preferably 50% to 200%, and even more preferably 70% to 150%. s Preferably, it is 40% or more, more preferably 50% or more, even more preferably 70% or more, preferably 210% or less, more preferably 200% or less, and even more preferably 150% or less.

[0084] The above r s This can also be described as the ratio of the total area that the silane coupling agent can cover to the surface area of ​​the MgO being treated. s When the lower limit is within the above range, the coating rate of MgO by the silane coupling agent can be increased, and r sSince the upper limit is within the above range, it is easy to increase the coating efficiency with silane coupling agents.

[0085] The area occupied by one molecule of the above silane coupling agent can be calculated based on the area occupied by the Si-O- group bonded to MgO, for example, 13 × 10⁻⁶. -20 (m 2 ) is acceptable.

[0086] Magnesium oxide having the above-mentioned surface treatment layer can be produced by wet processing.

[0087] Specifically, this involves obtaining a second magnesium oxide having a surface treatment layer by surface treating a first magnesium oxide with a surface treatment agent containing a silane coupling agent. The above surface treatment also includes, within the technical scope of this disclosure, a method for producing magnesium oxide by wet treatment.

[0088] It is believed that by performing the above surface treatment by a wet process, the silane coupling agent can be uniformly adhered to the MgO surface.

[0089] In this disclosure, wet treatment may mean a treatment in which a mixture containing the object to be surface treated and the surface treatment agent goes through a slurry state. The slurry may be, for example, a mixed liquid with 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.

[0090] In this disclosure, the solid content of the mixture means the residue after heating the mixture at 105°C for 1 hour, and the solid content concentration means the value obtained by dividing the total mass of the residue by the total mass of the mixture subjected to heating.

[0091] The surface treatment agent containing the silane coupling agent described above is synonymous with the surface treatment agent used to form the surface treatment layer described above.

[0092] The first magnesium oxide mentioned above can typically be magnesium oxide without a surface treatment layer, i.e., MgO.

[0093] The specific surface area of ​​the first magnesium oxide described above is preferably 0.01 m². 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 It may be less than or equal to / g. The specific surface area of ​​the first magnesium oxide is preferably 0.01m². 2 / g or more, more preferably 0.05m 2 / g or more, more preferably 0.1m 2 / g or more, preferably 10m 2 Less than / g, more preferably 5.0m 2 / g or less, more preferably 3.0m 2 It may be less than / g.

[0094] The specific surface area of ​​the first magnesium oxide described above is preferably 0.01 m². 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 It may be less than or equal to / g. The specific surface area of ​​the first magnesium oxide is preferably 0.01m². 2 / g or more, more preferably 0.05m 2 / g or more, more preferably 0.1m 2 / g or more, preferably 10m 2 Less than / g, more preferably 5.0m 2 / g or less, more preferably 3.0m 2 It may be less than / g.

[0095] The average particle size of the first magnesium oxide described above is 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 described above is preferably 0.5 μm or more, more preferably 1.0 μm or more, 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.

[0096] The average particle size of the first magnesium oxide described above 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 described above is preferably 0.5 μm or more, more preferably 1.0 μm or more, 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 30 μm or less.

[0097] The above surface treatment agent is represented by the above formula (2) r s However, it can be used in an amount that is preferably 40% to 210%, more preferably 50% to 200%, and even more preferably 70% to 150%.

[0098] In a preferred embodiment, the above manufacturing method is A first mixture is obtained by mixing an organic solvent with a first magnesium oxide. A surface treatment agent containing a silane coupling agent is mixed with the first mixture to obtain a second mixture. From the second mixture described above, the organic solvent is removed to obtain a second magnesium oxide precursor. This may include heating and / or drying the above-mentioned second magnesium oxide precursor to obtain a second magnesium oxide having a surface treatment layer.

[0099] As the above organic solvent, an organic solvent that can be miscible with or dissolve the silane coupling agent is preferred.

[0100] The boiling point of the above organic solvent may preferably be 70°C to 140°C, more preferably 75°C to 130°C, and even more preferably 80°C to 120°C. Having the boiling point of the organic solvent within this range ensures good stability of the surface treatment and facilitates subsequent heating and / or drying of the precursor.

[0101] Preferably, the organic solvents mentioned above are alcoholic solvents, specifically ethanol, isopropyl alcohol, and butanol.

[0102] In the first mixed solution described above, the amount of 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, per 100 parts by mass of the first magnesium oxide.

[0103] The first mixed solution described above may further contain water. The amount of water may be preferably 0 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, and even more preferably 0.05 to 3 parts by mass, relative to 100 parts by mass of the organic solvent contained in the first mixed solution.

[0104] If the first mixture described above contains water, the mixing order of the organic solvent, the first magnesium oxide, and the water is not particularly limited. For example, the organic solvent and water may be mixed first, and then the mixture may be further mixed with the magnesium oxide; or the organic solvent and magnesium oxide may be mixed first, and then the mixture may be further mixed with the water; or the organic solvent, water, and magnesium oxide may be mixed simultaneously. The mixing of the above organic solvent and the first magnesium oxide can be carried out, for example, by stirring and / or ultrasonic treatment. The stirring can be performed using a magnetic stirrer and a mechanical stirrer. Using a magnetic stirrer allows for easy control of stirring, while using a mechanical stirrer enables uniform mixing even when the viscosity of the mixture is high. Baffle plates may be attached to the stirring tank during the stirring process. Attaching baffle plates can improve stirring efficiency. Furthermore, ultrasonic treatment can break down the agglomeration of the first magnesium oxide, resulting in a more uniform mixture.

[0105] The preparation of the first mixture can be carried out under conditions where the temperature of the first mixture is preferably between 10°C and 40°C, more preferably between 15°C and 30°C.

[0106] The surface treatment agent containing the silane coupling agent described above is synonymous with the surface treatment agent used to form the surface treatment layer described above.

[0107] The above surface treatment agent is represented by the above formula (2) r s However, it can be used in an amount preferably between 100% and 500%, more preferably between 100% and 400%, and even more preferably between 100% and 300%. Also, r s The amount used is preferably 100% or more, preferably 500% or less, more preferably 400% or less, and even more preferably 300% or less. s By having the lower limit within the above range, the probability of contact between the surface treatment agent and the magnesium oxide surface is increased, and it is expected that the surface treatment reaction will be promoted. On the other hand, the above r s Because the upper limit is within the above range, the amount of silane coupling agent added will be appropriate relative to the surface area of ​​magnesium oxide, which is expected to reduce manufacturing costs, maintain thermal conductivity even when mixed with resin, and suppress bleed-out.

[0108] The above surface treatment agent is represented by the above formula (2) r sHowever, it can be used in an amount that is preferably 40% to 210%, more preferably 50% to 200%, and even more preferably 70% to 150%.

[0109] Before mixing the surface treatment agent with the first mixture, the first solution may be allowed to stand for a certain period of time. This procedure is thought to facilitate more uniform mixing of the organic solvent and the first magnesium oxide.

[0110] The mixing of the above surface treatment agent and the first mixed solution can be carried out by the stirring treatment and / or ultrasonic treatment. By performing the mixing by stirring treatment and / or ultrasonic treatment, a more uniform mixing is possible, and it is believed that a more uniform surface treatment layer can be formed in the resulting second magnesium oxide.

[0111] The preparation of the second mixture described above can be carried out at a temperature such that the temperature of the second mixture is above the melting point of the silane coupling agent and below the boiling point of the organic solvent. Specifically, it can be carried out under conditions where the temperature is preferably between 10°C and 40°C, and more preferably between 15°C and 30°C. It is believed that mixing the surface treatment agent and the first mixture at such a temperature allows for more uniform stirring, and that a more uniform surface treatment layer can be formed in the resulting second magnesium oxide.

[0112] Methods for removing the organic solvent from the second mixture include, for example, filtration, distillation, centrifugation, and freeze-drying. Filtration allows for efficient removal of the organic solvent. Distillation makes it easy to remove only the organic solvent. Centrifugation has a high separation power for solids and liquids, making it easy to remove the organic solvent even when the viscosity of the second mixture is high. Freeze-drying makes it easy to suppress the aggregation of magnesium oxide.

[0113] The temperature at which the obtained second magnesium oxide precursor is heated and / or dried is not particularly limited, but should be sufficient to dry the solvent and be below the decomposition temperature of the silane coupling agent. The temperature at which the second magnesium oxide precursor is heated and / or dried is preferably 80°C to 250°C, more preferably 100°C to 220°C, and even more preferably 120°C to 200°C. The time for heating and / or drying the second magnesium oxide precursor is preferably 30 minutes to 48 hours, more preferably 1 hour to 24 hours. By heating and / or drying the precursor under these conditions, the reaction between the silane coupling agent and magnesium oxide proceeds, and a surface treatment layer can be formed.

[0114] The above heating and / or drying can be carried out using, for example, a hot air dryer, a microwave dryer, or a rotary dryer. Hot air dryers are highly versatile and can perform heating and drying with high efficiency. Rotary dryers are suitable for heating and drying large quantities of precursors with high efficiency. Microwave dryers do not require a high-temperature heat source, making it easy to reduce energy consumption.

[0115] The magnesium oxide of this disclosure may be produced by a method different from the production method in the embodiments described above, and the method for producing magnesium oxide of this disclosure is not limited to the one that provides the magnesium oxide described above.

[0116] The above magnesium oxide can be preferably used as a thermally conductive material, particularly as a heat dissipation filler. The heat dissipation filler is used to form a heat dissipation member by mixing it with a resin material, a rubber material, etc. Examples of the above resin material include thermoplastic resins such as polyolefin resins, polyamide resins, and polyphenylene sulfide resins, as well as thermosetting resins such as epoxy resins, phenolic resins, silicone resins, urea resins, melamine resins, and unsaturated polyesters. Examples of the above rubber material include silicone rubber, butyl rubber, butadiene rubber, acrylic rubber, ethylene propylene rubber, urethane rubber, and urethane rubber silicone resin.

[0117] In a composition comprising magnesium oxide and a resin material and / or a rubber material, the volume ratio of magnesium oxide (magnesium oxide / (resin material and / or rubber material + magnesium oxide)) to the total of the resin material and / or rubber material and magnesium oxide is preferably 1 to 90, more preferably 5 to 60, and even more preferably 10 to 50.

[0118] The above composition has a torque, as measured by the following method, preferably 53 N·m or less, more preferably 50 N·m or less, even more preferably 45 N·m or less, and even more preferably 40 N·m or less, and may be, for example, 10 N·m or more, 15 Pa·s or more, and even more preferably 20 N·m or more. [Method for measuring torque] Ethylene-octene polyolefin resin is heated to 120°C and kneaded for 10 minutes. Then, magnesium oxide is added to the ethylene-octene polyolefin resin so that the volume ratio of the ethylene-octene polyolefin resin to magnesium oxide is 51:49. The mixture is then kneaded again at 120°C for 15 minutes, and the torque (N·m) is measured at a rotation speed of 30 rpm.

[0119] The above composition has a viscosity, as measured by the following method (i), 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. [Method for measuring viscosity (i)] A bisphenol-type 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 a rotation speed of 500 rpm to obtain a resin composition. Using a rheometer, a 25 mm diameter disposable parallel plate and an 80 mm diameter disposable cup are used, with a temperature of 25°C, a gap distance of 1 mm, and a measurement shear rate range of 0-20 s. -1 The viscosity (Pa·s) is measured under the condition of a measurement time of 20 seconds.

[0120] The above composition has a viscosity, as measured by the following method (ii), 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. [Method for measuring viscosity (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 a rotation speed of 500 rpm to obtain a resin composition. Using a rheometer, a 25 mm diameter disposable parallel plate and an 80 mm diameter disposable cup are used, at a temperature of 23°C, a gap distance of 1 mm, and a measurement shear rate range of 0-20 s. -1 The viscosity (Pa·s) is measured under the condition of a measurement time of 20 seconds.

[0121] The above polyfunctional acrylic monomers can be any compound having two or more (meth)acryloyl groups in one molecule, and examples include difunctional (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 more (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. Among these, trifunctional or more (meth)acrylic monomers are preferred, with pentaerythritol tri(meth)acrylate and pentaerythritol tetra(meth)acrylate being preferred.

[0122] The molecular weight of the polyfunctional acrylic monomer is preferably 150 or more and 800 or less, more preferably 250 or more and 400 or less.

[0123] When the magnesium oxide of the present disclosure is mixed with a resin, it is possible to suppress an increase in torque and viscosity. As a result, the load on the apparatus during the production of the resin composition or the heat dissipation material can be reduced, and an improvement in the moldability of the resin material containing magnesium oxide is also expected.

[0124] In such a heat dissipation member, the magnesium oxide may be used alone as a heat dissipation filler, or the magnesium oxide and one or more other fillers selected from metal hydroxides, metal oxides, and metal nitrides may be used in combination. The heat dissipation filler and other fillers used in the heat dissipation member may or may not be surface-treated. That is, these heat dissipation fillers and other fillers may or may not have a surface treatment layer. Further, the shape and particle diameter of the heat dissipation filler and other fillers are not particularly limited. By subjecting the heat dissipation filler using the magnesium oxide of the present disclosure to wet treatment, in addition to the high durability (heat conductivity maintenance property) of the heat dissipation member, it becomes easier to mix with the resin (the viscosity / torque during mixing becomes low), and a large amount can be filled / mixed. As a result, the load on the apparatus during production is reduced, and it becomes possible to increase the heat conductivity.

[0125] 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 sealing materials; 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 bases, household appliances (particularly, inverters, etc.), and LEDs.

[0126] In addition, the magnesium oxide can also be used as a filler for a compound. The filler is used to form a compound by mixing it with a resin or other additives. Examples of the resin include thermoplastic resins such as polyolefin resins, polyamide resins, polyphenylene sulfide resins, and thermosetting resins such as epoxy resins, phenol resins, silicone resins, urea resins, melamine resins, and unsaturated polyesters.

Example

[0127] The present disclosure will be described more specifically by the following examples, but the present disclosure is not limited thereto.

[0128] (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 a silane coupling agent A having an alkyl chain at the end. (Molecular weight (MW) 433)

[0129] (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 a silane coupling agent B having an alkyl chain at the end. (Molecular weight (MW) 433)

[0130] (Synthesis Example 3: Silane Coupling Agent C) 10.3 parts by weight of 3-isocyanatopropyltriethoxysilane and 50.0 parts by weight of Sylaplane FM-0411 (manufactured by JNC, terminal OH-containing dimethylpolysiloxane, Mn 1000) were placed in a 100 mL eggplant-shaped flask, and stirred at 60 °C for 6 hours to obtain a silane coupling agent C having an alkyl chain at the end. (Weight average molecular weight (Mw) 1247)

[0131] (Synthesis Example 4: Silane Coupling Agent D) 2.6 parts by weight of 3-isocyanatopropyltriethoxysilane and 50.0 parts by weight of Sylaprene FM-0421 (manufactured by JNC, dimethylpolysiloxane containing terminal OH groups, Mn 5000) were placed in a 100 mL round-bottom flask and stirred at 60°C for 6 hours to obtain silane coupling agent D, which has alkyl chains at the ends. (Weight-average molecular weight (Mw) 5247)

[0132] (Example 1) 400 parts by weight of isopropanol and 200 parts by weight of magnesium oxide (A) were added to a 1 L round-bottom flask and stirred at 30°C and 800 rpm for 1 hour. While maintaining stirring, 1.8 parts by weight of silane coupling agent A was added and stirred for another hour under the same conditions. After stirring, the isopropanol was removed to obtain magnesium oxide whose surface was coated with the silane coupling agent. The obtained magnesium oxide was heated in a dryer at 120°C for 6 hours to advance the curing reaction, and magnesium oxide with a completed surface coating was prepared by a wet method. (r s :102%, particle size (D50) of surface-treated magnesium oxide: 2.5 μm, specific surface area of ​​surface-treated magnesium oxide: 1.5 m² 2 / g)

[0133] (Examples 2-15, Comparative Examples 2, 7) For each of the compositions shown in Tables 1 and 2, magnesium oxide with a completed surface coating was prepared by a wet process following the same steps as in Example 1. In Tables 1 and 2, magnesium oxide (A) has a specific surface area of ​​1.6 m². 2 / g represents magnesium oxide with an average particle size of 2.5 μm. IPA represents isopropyl alcohol. Furthermore, 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).

[0134] (Comparative Example 1) Untreated magnesium oxide was used.

[0135] (Comparative Example 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 complete, the mixture was heated at 150°C for 30 minutes to obtain magnesium oxide with a completed surface coating by a dry process.

[0136] (Comparative Examples 4-6) For each of the compositions shown in Table 1, magnesium oxide with a completed surface coating was prepared by a dry process following the same steps as in Comparative Example 3.

[0137] The magnesium oxide obtained in the examples and comparative examples was evaluated by the following method.

[0138] (particle size measurement) Measurements were taken using the Microtrac-Bell MT3300EXII laser diffraction / scattering particle size distribution analyzer. Ethanol was used as the solvent. As a pretreatment before measurement, the ethanol and the sample were mixed, and the sample was dispersed in the ethanol by sonication.

[0139] (specific surface area measurement) Measured with the specific surface area and pore size distribution measuring device BELsorp-max of Microtrack Bell Co., Ltd.

[0140] (Dyne value) As solutions with known dyne values, wetting tension test mixture No. 25.4, No. 30.0, No. 35.0, No. 40.0, No. 45.0, No. 50.0 (manufactured by Fujifilm Wako Pure Chemical Corporation) and water were prepared. 0.01 part by weight of magnesium oxide prepared in the examples and comparative examples was added to 2 mL of each liquid adjusted to 25°C, and the lowest dyne value at which all the added particles floated on the liquid surface was taken as the dyne value of the surface-coated magnesium oxide.

[0141] (Humidity resistance test) 3.0 g of the 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 1 week, and the weight change before and after the test was measured. In order to compare horizontally between particles with different particle sizes and specific surface areas, the value obtained by dividing the weight change rate by the specific surface area was also described.

[0142] [Table 1]

[0143] [Table 2]

[0144] Examples 1 to 16 are examples of the present disclosure, and it was confirmed that they have good humidity resistance. All of Comparative Examples 1 to 7 are examples where the dyne value is 45 mN / m or more, and the humidity resistance was not sufficiently satisfactory.

[0145] (Example 17) 24 parts by weight of ENGAGE8200 (DOW, ethylene-octene polyolefin resin, MFR: 5g / 10min, Mooney Viscosity (121℃): 8MU, glass transition temperature: -53℃) was placed in a Branbender plasticorder and heated to 120℃ and kneaded for 10 minutes to soften the resin. 96 parts by weight of the magnesium oxide obtained in Example 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 15 minutes of kneading was defined as the torque of the resin composition.

[0146] (Example 18, Comparative Examples 8-9) In Example 17, a resin composition was obtained and the torque was measured in the same manner as in Example 17, except that magnesium oxide shown in Table 3 was used instead of the magnesium oxide obtained in Example 1.

[0147] [Table 3]

[0148] Examples 17 and 18 are embodiments of the present disclosure, in which the torque of the mixture when mixed with resin was suppressed. Comparative Examples 8 and 9 are examples where the dyne value of magnesium oxide was 45 mN / m or higher, and the torque was not sufficiently suppressed when mixed with resin.

[0149] (Example 19) 25 parts by weight of jER-828 (manufactured by Mitsubishi Chemical, bisphenol A type epoxy resin, viscosity at 25°C: 12-15 Pa·s, epoxy equivalent: 184-194 g / eq) and 33 parts by weight of magnesium oxide prepared in Example 7 were added to a 50 mL glass bottle. The mixture was stirred at 25°C and 500 rpm for 1 hour to obtain a resin composition in which magnesium oxide was dispersed.

[0150] Viscosity measurements were performed on the obtained resin composition. Specifically, a 25mm disposable parallel plate and an 80mm disposable cup were attached to an Anton Paar Japan rheometer (MCR series), and viscosity measurements were performed under the following conditions: 1s -1 The viscosity was evaluated. Measurement conditions Measurement mode: Continuous lamp measurement Temperature: 25℃ Gap distance: 1mm Measurement shear rate range: 0~20s -1 Measurement time: 20s

[0151] (Examples 20-21, Comparative Examples 10-12) In Example 19, a resin composition was obtained in the same manner as in Example 19, except that the magnesium oxide shown in Table 4 was used instead of the magnesium oxide obtained in Example 7. The viscosity of the obtained resin composition was measured under the same conditions as in Example 19.

[0152] [Table 4]

[0153] Examples 1 to 21 are embodiments of the present disclosure, in which viscosity was suppressed when mixed with resin. Comparative Examples 10-12 are examples where the dyne value of magnesium oxide was 45 mN / m or higher, and the viscosity of the mixture when mixed with the resin was not sufficiently suppressed.

[0154] (Example 22) In a 50 mL glass bottle, 10 parts by weight of Aronics M-306 (manufactured by Toagosei, polyfunctional acrylic monomer, viscosity at 25°C: 0.45~0.75 Pa·s) and 20.3 parts by weight of magnesium oxide prepared in Example 7 were added. The mixture was 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.

[0155] Viscosity measurements were performed on the obtained resin composition. Specifically, a 25mm disposable parallel plate and an 80mm disposable cup were attached to an Anton Paar Japan rheometer (MCR series), and viscosity measurements were performed under the following conditions: 1s -1 The viscosity was evaluated. Measurement conditions Measurement mode: Continuous lamp measurement Temperature: 23℃ Gap distance: 1mm Measurement shear rate range: 0~20s -1 Measurement time: 20s

[0156] (Examples 23-24, Comparative Examples 13-14) In Example 22, a resin composition was obtained in the same manner as in Example 22, except that the magnesium oxide shown in Table 5 was used instead of the magnesium oxide obtained in Example 7. The viscosity of the obtained resin composition was measured under the same conditions as in Example 22.

[0157] [Table 5]

[0158] Examples 22-24 are embodiments of the present disclosure, in which viscosity was suppressed when mixed with resin. Comparative Examples 10-12 are examples where the dyne value of magnesium oxide was 45 mN / m or higher, and the viscosity of the mixture when mixed with the resin was not sufficiently suppressed. [Industrial applicability]

[0159] The magnesium oxide of the present invention is preferably used as a thermally conductive material, particularly as a heat dissipation filler. The heat dissipation filler is used to form a heat dissipation member by mixing it with a resin material, rubber, or the like. Examples of the heat dissipation components mentioned above 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 sealing materials; 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 automobiles (especially inverters, ECUs, LiBs, etc.), mobile devices such as smartphones, communication equipment, communication base stations, electrical appliances (especially inverters, etc.), and devices such as LEDs.

Claims

1. A method for producing magnesium oxide, The method includes obtaining a second magnesium oxide having a surface treatment layer by surface treating a first magnesium oxide with a surface treatment agent containing a silane coupling agent. The second magnesium oxide has a Dyne value of less than 45 mN / m and a specific surface area of ​​1.3 m² / g or more and 10 m² / g or less. The aforementioned surface treatment is a method for producing magnesium oxide, carried out by a wet treatment.

2. The aforementioned surface treatment is A first mixture is obtained by mixing an organic solvent with a first magnesium oxide. A second mixture is obtained by mixing the surface treatment agent with the first mixture. From the second mixture, the organic solvent is removed to obtain a second magnesium oxide precursor, and A method for producing magnesium oxide according to claim 1, comprising heating and / or drying the precursor of the second magnesium oxide to obtain a second magnesium oxide having a surface treatment layer.

3. The following formula (2): [Math 1] [In formula (2), n s represents the amount of substance (mol) of the silane coupling agent. N A represents Avogadro's number (mol⁻¹), S s represents the area occupied by one molecule of silane coupling agent (m²). m represents the amount of magnesium oxide added (g). [s m represents the specific surface area (m²·g⁻¹) of magnesium oxide] A method for producing magnesium oxide according to claim 1, wherein the value r s, represented by , is 40% or more and 500% or less.

4. The silane coupling agent is the following formula (1): R 1 n -Si-(OR 2 ) m...(1) [In formula (1), R1 independently represents -L1 -R3, L1 independently represents a single bond or a divalent organic group. Each R3 independently represents one selected from the group consisting of C1-30 alkyl groups, C2-30 alkenyl groups, C6-30 aromatic hydrocarbon groups, and -SiR43 groups. Each R4 independently represents a C1-6 hydrocarbon group. Each R2 independently represents a C1-4 alkyl group or a hydrogen atom. n represents an integer from 1 to 3. m represents an integer between 1 and 3. A method for producing magnesium oxide according to claim 1, comprising a compound represented by [the compound].

5. The method for producing magnesium oxide according to claim 1, wherein the average particle size of the second magnesium oxide is 0.5 μm or more and 50 μm or less.

6. A method for manufacturing a heat dissipation member, comprising mixing magnesium oxide obtained by the manufacturing method described in any one of claims 1 to 5 with a resin material and / or a rubber material.

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