Alumina fiber aggregate, process for producing the same, and use thereof

• US 8,273,816 B2
• Filed: 09/29/2008
• Issued: 09/25/2012
• Est. Priority Date: 10/11/2007
• Status: Active Grant

• Current Assignee: Denki Kagaku Kogyo Kabushiki Kaisha (TDK Corporation)
• Original Assignee: Denki Kagaku Kogyo Kabushiki Kaisha (TDK Corporation)
• Inventors: Ohshima, Yasutaka, Hirano, Isamu, Higuchi, Takayuki
• Primary Examiner(s): LEE, DORIS L
• Application Number:
  US12/682,471
• Publication Number:
  US 20100207054A1
• Time in Patent Office: 1,457 Days
• Field of Search: 524/430
• US Class Current: 524/430
• CPC Class Codes: C04B 2235/526 characterised by the length of the fibers
• CPC Class Codes: C04B 2235/5264 characterised by the diameter of the fibers
• CPC Class Codes: C04B 35/62236 Fibres based on aluminium oxide
• CPC Class Codes: C04B 35/62245 rich in aluminium oxide
• CPC Class Codes: C04B 35/6261 Milling
• CPC Class Codes: C08J 5/041 with metal fibres

Abstract

An object of the invention is to provide an alumina fiber aggregate which, when used as a filler in various materials such as, e.g., resins, coating materials, metals, and ceramics, enables the mixtures to have reduced viscosity and thereby heightens the productivity of products containing alumina fibers, and which enables cured thermosetting resins to have a sufficiently heightened thermal conductivity.

This alumina fiber aggregate, when examined by the electron microscope method, gives a frequency distribution regarding number of fibers, wherein the number of fibers having a fiber length of 50-200 μm is 70% or more (including 100%), the number of fibers having a fiber length smaller than 50 μm is 30% or less (including 0), the number of fibers of 50-100 μm is 30-50%, the number of fibers longer than 100 μm but not longer than 200 μm is 30-50%, and the number of fibers longer than 200 μm is 20% or less (including 0). The fibrous mass comprises 70-100% by mass of Al₂O₃ and 0-30% by mass of SiO₂.

Claims

1. An alumina fiber aggregate which, when examined by the electron microscope method, gives a frequency distribution regarding number of fibers, wherein the number of fibers having a fiber length of 50-200 μ

m is 70% or more (including 100%), the number of fibers having a fiber length smaller than 50 μ

m is 30% or less (including

     0), the number of fibers of 50-100 μ

m is 30-50%, the number of fibers longer than 100 μ

m but not longer than 200 μ

m is 30-50%, and the number of fibers longer than 200 μ

m is 20% or less (including

     0), and which comprises 70-100% by mass of Al₂O₃ and 0-30% by mass of SiO₂.

2. The alumina fiber aggregate according to claim 1, wherein the number of fibers having a fiber length of 50-200 μ

m is 80% or more (including 100%), the number of fibers having a fiber length smaller than 50 μ

m is 10% or less (including

     0), the number of fibers of 50-100 μ

m is 35-45%, the number of fibers longer than 100 μ

m but not longer than 200 μ

m is 35-45%, the number of fibers longer than 200 μ

m is 15% or less (including

     0), and the number of fibers longer than 300 μ

m is 5% or less (including

     0),

wherein the fiber aggregate has an average fiber diameter of 3-10 μ

m and the number of fibers having a fiber diameter smaller than 3 μ

m is less than 5%.

3. A cured thermosetting resin which comprises the alumina fiber aggregate according to claim 1 or 2.