Paper comprising heat treated bio-soluble inorganic fibers, and method and equipment for making same

#The invention relates to inorganic fiber paper, a method for producing the same and equipment using the same. In particular, the invention relates to improvement in recovery after compression heating of inorganic fiber paper containing bio-soluble inorganic fibers.

#Inorganic fiber paper is lightweight, easy to handle and improved heat resistance, and hence, is used as a heat resisting sealing material, for example. On the other hand, in recent years, a problem has been pointed out that inorganic fibers are inhaled into a human body and the inhaled fibers invade the lung to cause disorders. Under such circumstances, bio-soluble inorganic fibers which do not cause or hardly cause disorders even if inhaled into a human body have been developed (Patent Document 1, identified below, for example).

#Patent Document 1: Japanese Patent Application Publication JP-A-2002-068777, published Mar. 8, 2002, of Japanese Patent Application 2000-257630, filed Aug. 28, 2000, to which U.S. Pat. No. 6,627,568 corresponds.

#FIG. 1 is a view showing one example of the evaluation results of recovery of inorganic fiber paper after compression heating in the example according to one embodiment of the invention.

#One embodiment of the invention will be described below. The invention is, however, not limited to this embodiment.

#First, a method for producing inorganic fiber paper according to this embodiment (hereinafter referred to as the “method of the embodiment”) will be described. The method of the embodiment comprises the first step of subjecting amorphous bio-soluble inorganic fibers to a heat treatment (hereinafter referred to as the “heat treatment step”) and the second step of making inorganic fiber paper comprising the heat-treated bio-soluble inorganic fibers and a binder (hereinafter referred to as the “paper-making step”).

#In the heat treatment step, first, amorphous bio-soluble inorganic fibers are prepared. No specific restrictions are imposed on bio-soluble inorganic fibers insofar as they are inorganic fibers and have bio-solubility (property of being decomposed in a living body even if they are inhaled into the lung of the living body, for example). At least part of the bio-soluble inorganic fibers is amorphous, and the amorphous nature can be confirmed by X-ray powder diffraction (XRD) measurement.