Alumina fiber aggregate and catalytic converter support mat comprising the same

• US 20060216225A1
• Filed: 03/20/2006
• Published: 09/28/2006
• Est. Priority Date: 09/22/2003
• Status: Abandoned Application

• Current Assignee: Mitsubishi Chemical Functional Products, Inc. (Mitsubishi Chemical Group Corp.)
• Original Assignee: Mitsubishi Chemical Functional Products, Inc. (Mitsubishi Chemical Group Corp.)
• Inventors: Sasaki, Toshiaki, Kakikura, Eisaku
• Application Number:
  US11/378,626
• Publication Number:
  US 20060216225A1
• Time in Patent Office: Days
• US Class Current: 423/625
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/3418 Silicon oxide, silicic acids, or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint glass constituents C04B2235/36
• CPC Class Codes: C04B 2235/441 Alkoxides, e.g. methoxide, tert-butoxide
• CPC Class Codes: C04B 2235/444 Halide containing anions, e.g. bromide, iodate, chlorite
• CPC Class Codes: C04B 2235/5264 characterised by the diameter of the fibers
• CPC Class Codes: C04B 2235/5268 Orientation 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 35/63416 Polyvinylalcohols [PVA]; Polyvinylacetates
• CPC Class Codes: C04B 35/63468 Polyamides
• CPC Class Codes: C04B 35/63488 Polyethers, e.g. alkylphenol polyglycolether, polyethylene glycol [PEG], polyethylene oxide [PEO]
• CPC Class Codes: D04H 1/4234 Metal fibres
• CPC Class Codes: D04H 1/43838 Ultrafine fibres, e.g. microfibres
• CPC Class Codes: D04H 1/72 the fibres being randomly arranged
• CPC Class Codes: Y10T 428/268 Monolayer with structurally defined element
• CPC Class Codes: Y10T 428/298 Physical dimension

Abstract

An alumina fiber aggregate which is minimized in scatter of fibers, excels in handling characteristics and working environmental hygiene and finds its useful application to support mats for catalytic converters and such is provided. An alumina fiber aggregate comprising alumina short fibers having such properties that when diameters of said alumina short fibers are represented by x (μm), the rate at which the natural logarithmic value lnx in lognormal distribution of x is less than ln3 is not more than 2%, and the value left after deducting from the length-weighted geometric mean of said fiber diameters a value twice its standard error is not more than 6 μm; and a support mat for catalytic converters comprising such an alumina fiber aggregate.

Claims

1. An alumina fiber aggregate comprising alumina short fibers and having such properties that when the diameters of said alumina short fibers are represented by x (μ

), the rate at which the natural logarithmic value lnx in lognormal distribution of x is less than ln3 is not more than 2%, and the value left after deducting from the length-weighted geometric mean of said fiber diameters a value twice its standard error is not more than 6 μ

m.

2. An alumina fiber aggregate according to claim 1, wherein the rate at which the natural logarithmic value in lognormal distribution of diameters x of said alumina short fibers is less than ln3 is not more than 1%.

3. An alumina fiber aggregate according to claim 1, wherein the ratio of the alumina short fibers with diameters of not less than 10 μ

m is not more than 4%.

4. An alumina fiber aggregate according to claim 1, wherein the sum of the length-weighted geometric mean diameter of said alumina short fibers and the value twice its standard error is not more than 6.5 μ

m.

5. An alumina fiber aggregate according to claim 1, wherein the difference between the length-weighted geometric mean of diameters of said alumina short fibers and the value twice its standard error is not more than 5.5 μ

m.

6. An alumina fiber aggregate according to claim 1, wherein the length-weighted geometric mean diameter is 4.0 to 5.5 μ

m.

7. An alumina fiber aggregate according to claim 1, wherein said alumina short fibers are those obtained by a precursor fiber forming method.

8. A support mat for catalytic converters, said support mat comprising an alumina fiber aggregate as defined in claim 1.