Thermal insulator and method of manufacturing the same

• US 9,950,963 B2
• Filed: 04/29/2016
• Issued: 04/24/2018
• Est. Priority Date: 12/22/2010
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Sakamoto, Akifumi, Goto, Yoshihiko, Ito, Yasuo, Maeda, Ken
• Primary Examiner(s): Theisen, Mary Lynn F
• Application Number:
  US15/143,007
• Publication Number:
  US 20160244371A1
• Time in Patent Office: 725 Days
• Field of Search: None
• CPC Class Codes: B28B 11/24 for curing, setting or hardening processes for influencing or modifying the setting or hardening ability of mortars, concrete or artificial stone compositions, in general C04B40/00
• CPC Class Codes: B28B 11/243 Setting, e.g. drying, dehydrating or firing ceramic articles B28B11/242 takes precedence
• CPC Class Codes: B28B 11/247 Controlling the humidity during curing, setting or hardening
• CPC Class Codes: C04B 14/062 Microsilica, e.g. colloïdal silica preparing microsilica slurries or suspensions C04B18/148
• CPC Class Codes: C04B 14/4631 Silica
• CPC Class Codes: C04B 2111/28 Fire resistance, i.e. materials resistant to accidental fires or high temperatures
• CPC Class Codes: C04B 30/02 containing fibrous materials
• CPC Class Codes: C04B 35/6269 Curing of mixtures
• CPC Class Codes: C04B 38/0038 by superficial sintering or bonding of particulate matter
• CPC Class Codes: C04B 40/0259 Hardening promoted by a rise in pressure C04B40/024 takes precedence
• CPC Class Codes: C04B 40/0263 Hardening promoted by a rise in temperature C04B40/024 takes precedence
• CPC Class Codes: F27D 7/06 Forming or maintaining special atmospheres or vacuum within heating chambers F27D7/02 takes precedence
• CPC Class Codes: Y10T 428/268 Monolayer with structurally defined element

Abstract

A thermal insulator with both excellent heat insulation and strength and a method of manufacturing the thermal insulator are provided.

A thermal insulator according to the present invention includes metal oxide fine particles with an average particle diameter equal to or smaller than 50 nm and a reinforcing fiber, wherein the thermal insulator has a bridge structure between the metal oxide fine particles which is formed by elution of part of the metal oxide fine particles. A method of manufacturing a thermal insulator according to the present invention includes a curing step of curing a dry pressed compact including metal oxide fine particles with an average particle diameter equal to or smaller than 50 nm and a reinforcing fiber under a pressurized vapor saturated atmosphere at a temperature equal to or higher than 100° C. for four hours and a drying step of drying the cured dry pressed compact.

Claims

1. A method of manufacturing a thermal insulator, comprising:

a curing step of curing a dry pressed compact including metal oxide fine particles with an average particle diameter equal to or smaller than 50 nm and a reinforcing fiber under a pressurized vapor saturated atmosphere at a temperature equal to or higher than 100°

C.,

wherein the metal oxide fine particles include alumina fine particles.

2. The method of manufacturing a thermal insulator according to claim 1, wherein

in the curing step, part of the metal oxide fine particles is eluted between the metal oxide fine particles to form a liquid bridge structure, and

in a drying step, the bridge structure is solidified.

3. The method of manufacturing a thermal insulator according to claim 1, wherein the metal oxide fine particles include silica fine particles.

4. The method of manufacturing a thermal insulator according to claim 1, wherein the dry pressed compact includes 50 to 98 mass % of the metal oxide fine particles and 2 to 20 mass % of the reinforcing fiber.

5. The method of manufacturing a thermal insulator according to claim 1, wherein

the dry pressed compact does not comprise a binder.

6. The method of manufacturing a thermal insulator according to claim 1, further comprising:

a step of mixing the metal oxide fine particles and the reinforcing fiber by a dry method to fabricate a dry mixture; and

a step of pressure-forming the dry mixture by a dry method to fabricate the dry pressed compact.

7. The method of manufacturing a thermal insulator according to claim 1, wherein the content of the alumina fine particles is 20 mass % or more.

8. The method of manufacturing a thermal insulator according to claim 1, wherein the dry pressed compact further includes a radiating and scattering material.

9. The method of manufacturing a thermal insulator according to claim 8, wherein the dry pressed compact includes:

50 to 98 mass % of the metal oxide fine particles;

2 to 20 mass % of the reinforcing fiber; and

5 to 40 mass % of the radiating and scattering material.

10. The method of manufacturing a thermal insulator according to claim 1, wherein the reinforcing fiber has an average fiber length of equal to or larger than 1 mm and equal to or smaller than 10 mm.

11. The method of manufacturing a thermal insulator according to claim 2, wherein

the bridge structure comprises a portion bridging an alumina fine particle and a silica fine particle;

and

the thermal insulator comprises alumina fine particles equal to or larger than 10 mass % and silica fine particles equal to or larger than 5 mass % based on the mass of the thermal insulator.