An objective of the present invention is to provide a pipe through which fluids can flow, in which thermal insulation in a space between an inner wall and an outer wall is achieved at low cost and high performance. The thermal insulation pipe of the present invention is a thermal insulation pipe formed by a double wall pipe of an inner pipe and an outer pipe. A thermal-insulating material to be filled in a space between the inner pipe and the outer pipe is made from an aerogel having a three-dimensional network structure with a framework constituted by a cluster of aggregation of primary particles. The thermal-insulating material includes fine particles having a three-dimensional network structure with a framework of the primary particles. A preferred form of such a thermal-insulating material is weakly bonded aerogel ultrafine particle generated by crushing at ultra-high speed a low-binding ultrafine aerogel generated from an aerogel with aging conditions during manufacturing process set to a low temperature and short time period.

Composite oxide fine particles are produced by sol-gel method under conditions in which coarse particles and aggregated particles are unlikely to be generated, and the composite oxide fine particles are further wet-filtered using a filter to remove the coarse particles and the aggregated particles. Then, a salt is added to a dispersion of the composite oxide fine particles to produce weak aggregates of the composite oxide fine particles in the dispersion. A solid content is separated from the dispersion of the composite oxide fine particles containing the aggregates, and then dried. The solid content is easily made finer because no firm aggregates are generated during the drying. That is, composite oxide fine particles containing no coarse particles and aggregated particles are obtained. Use of a known cracking means can further reduce the amount of coarse particles.

Composite oxide fine particles are produced by sol-gel method under conditions in which coarse particles and aggregated particles are unlikely to be generated, and the composite oxide fine particles are further wet-filtered using a filter to remove the coarse particles and the aggregated particles. Then, a salt is added to a dispersion of the composite oxide fine particles to produce weak aggregates of the composite oxide fine particles in the dispersion. A solid content is separated from the dispersion of the composite oxide fine particles containing the aggregates, and then dried. The solid content is easily made finer because no firm aggregates are generated during the drying. That is, composite oxide fine particles containing no coarse particles and aggregated particles are obtained. Use of a known cracking means can further reduce the amount of coarse particles.

Provided is a method of manufacturing a hybridized aerogel including preparing a silica sol including a silica precursor, a first organic solvent, and a first acidic catalyst, preparing an opacifier sol including an opacifier precursor, a second organic solvent, a gelation inducing agent, and a second acidic catalyst, forming a mixed sol by mixing the silica sol and the opacifier sol, forming a hybridized gel in which a silica gel and an opacifier gel are mixed by adding a basic catalyst to the mixed sol and making the mixed sol to be gelled, and acquiring a hybridized aerogel in which a silica aerogel and an opacifier aerogel are mixed by removing solvent from the hybridized gel.

Provided is a method of manufacturing a hybridized aerogel including preparing a silica sol including a silica precursor, a first organic solvent, and a first acidic catalyst, preparing an opacifier sol including an opacifier precursor, a second organic solvent, a gelation inducing agent, and a second acidic catalyst, forming a mixed sol by mixing the silica sol and the opacifier sol, forming a hybridized gel in which a silica gel and an opacifier gel are mixed by adding a basic catalyst to the mixed sol and making the mixed sol to be gelled, and acquiring a hybridized aerogel in which a silica aerogel and an opacifier aerogel are mixed by removing solvent from the hybridized gel.