Abstract: A process for producing the 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 ?m is 70% or more (including 100%), the number of fibers having a fiber length smaller than 50 ?m is 30% or less (including 0), the number of fibers of 50-100 ?m is 30-50%, the number of fibers longer than 100 ?m but not longer than 200 ?m is 30-50%, and the number of fibers longer than 200 ?m is 20% or less (including 0). The process including the steps of grinding cottony alumina-based fibers comprising 70-100% by mass of Al2O3 and 0-30% by mass of SiO2 while applying a pressure of 0.1-20 MPa thereto and then classifying the ground fibers.

Abstract: A process for producing the 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 ?m is 70% or more (including 100%), the number of fibers having a fiber length smaller than 50 ?m is 30% or less (including 0), the number of fibers of 50-100 ?m is 30-50%, the number of fibers longer than 100 ?m but not longer than 200 ?m is 30-50%, and the number of fibers longer than 200 ?m is 20% or less (including 0). The process including the steps of grinding cottony alumina-based fibers comprising 70-100% by mass of Al2O3 and 0-30% by mass of SiO2 while applying a pressure of 0.1-20 MPa thereto and then classifying the ground fibers.

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 ?m is 70% or more (including 100%), the number of fibers having a fiber length smaller than 50 ?m is 30% or less (including 0), the number of fibers of 50-100 ?m is 30-50%, the number of fibers longer than 100 ?m but not longer than 200 ?m is 30-50%, and the number of fibers longer than 200 ?m is 20% or less (including 0). The fibrous mass comprises 70-100% by mass of Al2O3 and 0-30% by mass of SiO2.

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 ?m is 70% or more (including 100%), the number of fibers having a fiber length smaller than 50 ?m is 30% or less (including 0), the number of fibers of 50-100 ?m is 30-50%, the number of fibers longer than 100 ?m but not longer than 200 ?m is 30-50%, and the number of fibers longer than 200 ?m is 20% or less (including 0). The fibrous mass comprises 70-100% by mass of Al2O3 and 0-30% by mass of SiO2.

Abstract: An indicator comprising azo dye(s), epoxy compound(s) and a separating membrane can be utilized for detection of the completion of thermal sterilization treatment in the medical field and also for thermal inspection in such various fields as testing, instrumentation and the like. The indicator can be used also for detection of the completion of alkylene oxide gas sterilization treatment by ethylene oxide gas or the like.