# US 11,111,391 B2 · Coated magnesium oxide particles and method of producing the same, and thermal conductive resin composition

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- Number: US 11,111,391 B2
- Document ID: US11111391B2
- Status: Granted
- Kind: B2
- Application number: 16/580,101
- Filed: 2019-09-24
- Published: 2020-01-16
- Granted: 2021-09-07
- Earliest claimed: 2017-03-28
- Assignees: Ube Material Industries, Ltd.
- Applicants: Ube Material Industries, Ltd.
- Inventors: Naoto Nishida; Koji Nakamura; Seiji Yamaguchi
- Web page: https://patentgrep.com/patent/US11111391B2

## CPC

- C09C 1/028: {Compounds containing only magnesium as metal}
- C09C 3/08: Treatment with low-molecular-weight {non-polymer} organic compounds {(C09C3/006, C09C3/048 take precedence)}
- C01F 5/02: Magnesia
- C08K 3/013: Fillers, pigments or reinforcing additives
- C08K 3/22: of metals
- C08K 5/09: Carboxylic acids; Metal salts thereof; Anhydrides thereof
- C08K 5/5403: {containing no other elements than carbon or hydrogen}
- C08K 9/04: Ingredients treated with organic substances {(treated with macromolecular compounds C08K9/08)}
- C08K 9/06: with silicon-containing compounds
- C08L 101/00: Compositions of unspecified macromolecular compounds
- C01P 2004/32: Spheres
- C01P 2004/51: Particles with a specific particle size distribution
- C01P 2004/61: Micrometer sized, i.e. from 1-100 micrometer
- C01P 2006/10: Solid density
- C01P 2006/11: Powder tap density
- C01P 2006/12: Surface area
- C01P 2006/19: Oil-absorption capacity, e.g. DBP values
- C08K 2003/2217: {of magnesium}
- C08K 2201/001: Conductive additives
- C08L 2203/20: use in electrical or conductive gadgets
- C09C: TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES (treatment of materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone C04B14/00, C04B18/00, C04B20/00); PREPARATION OF CARBON BLACK {; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS}
- C01F: COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; sulfides or polysulfides of magnesium, calcium, strontium, or barium C01B17/42; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds other than ammonia or cyanogen containing nitrogen and non-metals and optionally metals C01B21/082; amides or imides of silicon C01B21/087}; metal {imides or} amides C01B21/092, {C01B21/0923}; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanic acid C01C3/14; salts of cyanamide C01C3/16; thiocyanates C01C3/20; {double sulfates of magnesium with sodium or potassium C01D5/12; with other alkali metals C01D15/00, C01D17/00})
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

Coated magnesium oxide particles having high filling efficiency and high mass-productivity and suitable for a thermal conductive filler are provided, the coated magnesium oxide particles being coated magnesium oxide particles in which the surface of magnesium oxide particles is coated with at least one of a fatty acid and a fatty acid metal salt, and wherein X in relation to particles is defined as X=[a BET specific surface area diameter calculated from a BET specific surface area of the particles]÷[D50 of the particles], provided that D50 is a particle diameter at 50% accumulation in a cumulative particle size distribution of the particles, the magnesium oxide particles having X of less than 0.2 and D50 of 5 to 100 μm, and the coated magnesium oxide particles having X of 0.2 or more, D50 of 5 to 100 μm, and oil absorption of less than 25 mL/100 g.

## Claims

### Claim 1

Coated magnesium oxide particles in which the surface of magnesium oxide particles is coated with at least one of a fatty acid and a fatty acid metal salt, wherein
a raw material of the magnesium oxide particles is a sintered body of magnesium oxide,
X in relation to particles is defined as X=[a BET specific surface area diameter calculated from a BET specific surface area of the particles] ÷ [D50 of the particles], provided that D50 is a particle diameter at 50% accumulation in a cumulative particle size distribution of the particles,
the magnesium oxide particles have X of less than 0.2 and D50 of 5 to 100 μm, and
the coated magnesium oxide particles have X of 0.2 or more, D50 of 5 to 100 μm, and oil absorption of less than 25 mL/100 g.

### Claim 2 (depends on 1)

The coated magnesium oxide particles according to claim 1, wherein
the fatty acid is stearic acid, and the fatty acid metal salt is one or two or more selected from magnesium stearate, calcium stearate, and zinc stearate.

### Claim 3 (depends on 1)

The coated magnesium oxide particles according to claim 1, wherein
the surface of the magnesium oxide particles is surface-treated with a silane coupling agent.

### Claim 4 (depends on 3)

The coated magnesium oxide particles according to claim 3, wherein
the silane coupling agent includes at least one selected from a vinyl group, an amino group, a phenyl group, and derivatives of these substituents.

### Claim 5 (depends on 3)

The coated magnesium oxide particles according to claim 3, wherein
a percentage of mass increase after 48 hours under 85° C.-85% RH environment is 1% or less.

### Claim 6 (depends on 1)

A thermal conductive resin composition, comprising the coated magnesium oxide particles according to claim 1, filled in a resin.

### Claim 7 (depends on 1)

A method of producing the coated magnesium oxide particles according to claim 1, the method comprising
a coating step of adding at least one of a fatty acid and a fatty acid metal salt to magnesium oxide particles having X of less than 0.2 and D50 of 5 to 100 μm followed by mixing at 100 to 200° C. to obtain coated magnesium oxide particles in which the surface of the magnesium oxide particles is coated with at least one of the fatty acid and the fatty acid metal salt.

### Claim 8 (depends on 7)

The method of producing coated magnesium oxide particles according to claim 7, wherein
the fatty acid is stearic acid, and the fatty acid metal salt is one or two or more selected from magnesium stearate, calcium stearate, and zinc stearate.

### Claim 9 (depends on 7)

The method of producing coated magnesium oxide particles according to claim 7, further comprising, before the coating step,
a surface treatment step of adding a silane coupling agent to the magnesium oxide particles followed by mixing to surface-treat the surface of the magnesium oxide particles with the silane coupling agent.

### Claim 10 (depends on 9)

The method of producing coated magnesium oxide particles according to claim 9, wherein
the silane coupling agent includes at least one selected from a vinyl group, an amino group, a phenyl group, and derivatives of these substituents.