Abstract: A recording medium includes an ink-receiving layer on a substrate, in which the ink-receiving layer contains a hydrated alumina, an alkylsulfonic acid having 1 to 4 carbon atoms, and at least one salt of a sulfur compound represented by general formula (1) or (2): R1—SO2M1??general formula (1) R2—SO2—SM2??general formula (2) wherein R1 and R2 each represent an alkyl group, an aryl group, or a heterocyclic group; and M1 and M2 each represent an alkali metal, ammonium, or an alkanolamine. The proportion of the alkylsulfonic acid having 1 to 4 carbon atoms is in the range of 1.0% by mass to 2.0% by mass with respect to the hydrated alumina. The proportion of the salt of the sulfur compound is in the range of 0.2% by mass to 4.0% by mass with respect to the hydrated alumina.

Abstract: A recording medium includes an ink-receiving layer on a substrate, in which the ink-receiving layer contains hydrated alumina, a C1-4 alkylsulfonic acid, and a salt of a compound of general formula (1): X1?R1?(S)n?R2?X2, wherein n represents 1 or 2; X1 and X2 each independently represent H, NH2, or COOH, and at least one of X1 and X2 represents NH2 or COOH; R1 and R2 each independently represent alkylene, arylene, or heteroarylene, and they may be bonded to each other to form a ring, upon letting the proportion of the C1-4 alkylsulfonic acid be A percent by mass with respect to hydrated alumina, A is in the range of 1.0 to 2.0, and upon letting the proportion of the salt of the compound of general formula (1) be B percent by mass with respect to hydrated alumina, B is in the range of 0.5 to 5.0.

Abstract: The invention provides a recording medium having excellent ink absorbency and capable of forming a sharp image thereon. The recording medium has a substrate, and a first layer and an outermost layer provided on the substrate in this order, wherein the first layer contains at least one of alumina and alumina hydrate, the outermost layer contains a pigment and is lower in refractive index than the first layer, and the absolute dry coating amount of the outermost layer is 0.1 g/m2 or more and 0.5 g/m2 or less.

Abstract: In an ink jet recording medium having at least two ink receiving layers, the total content of boric acid, a borate, and a water-soluble zirconium salt of a lower ink receiving layer located close to a support substrate to the total content of alumina and an alumina hydrate thereof is higher than the total content of boric acid, a borate, and a water-soluble zirconium salt of an upper ink receiving layer located apart from the support substrate to the total content of alumina and an alumina hydrate thereof.

Abstract: The invention provides a method for producing a recording medium, comprising a step of coating one or more ink receiving layers provided on at least one surface of a substrate with an outermost layer coating liquid to form an outermost layer, an ink receiving layer, of said one or more ink receiving layers, which is nearest to the outermost layer containing alumina hydrate and a binder. The outermost layer coating liquid contains monodispersive and spherical cationic colloidal silica particles having an average particle size of 30 nm or more and 60 nm or less, polyvinyl alcohol having a saponification degree of 75% by mol or more and 85% by mol or less and a viscosity-average polymerization degree of 1,500 or more and 2,200 or less, and cationic polyurethane emulsion particles having an average particle size of 10 nm or more and 100 nm or less.

Abstract: The invention provides a recording medium comprising a substrate and an ink receiving layer that is provided on the substrate and contains alumina hydrate and a binder. A surface of the ink receiving layer is covered with a partial coating formed by a plurality of coatings containing a cationic polyurethane. The plurality of coatings have an average major diameter of 0.03 ?m or more and less than 1.00 ?m. The partial coating provides a coverage of 10% or more and less than 70% with respect to the surface of the ink receiving layer.

Abstract: The invention provides a recording medium having 2 or more ink receiving layers on a substrate, wherein an upper layer of the ink receiving layers, which is a layer most distant from the substrate, and a lower layer, which is a layer located just under the upper layer, contain at least one selected from alumina hydrate and alumina, an acid and a hydrophilic binder, the acid contained in the upper layer is a carboxylic acid represented by the general formula [I], and the acid contained in the lower layer is a sulfonic acid represented by the general formula [II].

Abstract: The invention provides an ink jet recording medium which attains the prevention of the bronzing of cyan ink and the prevention of the migration of magenta ink at the same time and is excellent in image characteristics. The ink jet recording medium comprises a substrate and an ink-receiving layer provided with at least an upper layer as the outermost layer and a lower layer as a layer lying just under the upper layer, both layers having a porous structure formed of an alumina hydrate and a binder, wherein both of the upper and lower layers contain an alkylsulfonic acid and only the lower layer contains a cationic polymer.

Abstract: The invention provides an ink jet recording medium which attains the prevention of the bronzing of cyan ink and the prevention of the migration of magenta ink at the same time and is excellent in image characteristics. The ink jet recording medium comprises a substrate and an ink-receiving layer provided with at least an upper layer as the outermost layer and a lower layer as a layer lying just under the upper layer, both layers having a porous structure formed of an alumina hydrate and a binder, wherein both of the upper and lower layers contain an alkylsulfonic acid and only the lower layer contains a cationic polymer.

Abstract: The present invention provides a dispersion of silica particle agglomerates having a sharp particle size distribution and capable of forming a porous coating film having a high transparency by drying.

Abstract: The present invention also provides a process for producing a colloidal dispersion of silica particle agglomerates having a specific surface area, as determined by nitrogen adsorption method, of 100 m2/g to 400 m2/g, an average secondary particle diameter of 20 nm to 300 nm and a pore volume of 0.5 ml/g to 2.0 ml/g, which comprises using a colloidal dispersion of silica particle agglomerates having a specific surface area, as determined by nitrogen adsorption method, of 300 m2/g to 1,000 m2/g and a pore volume of 0.4 ml/g to 2.0 ml/g as a seed dispersion, adding a feed solution comprising at least one of an aqueous active silicic acid solution and alkoxysilanes to the seed dispersion in small portions in the presence of an alkali to grow silica particle agglomerates.

Abstract: The present invention provides a dispersion of silica particle agglomerates having a sharp particle size distribution and capable of forming a porous coating film having a high transparency by drying.

Abstract: A synchronous position correction system for a self-controlled linear synchronous motor train includes a position detector for detecting a positional relationship between a propulsion winding provided on a track and a field pole provided on the train which is formed by a plurality of cars. A synchronous operation of the formed train is performed at a phase which is obtained by correcting a phase detected by the position detector on the basis of a difference between an average phase of the whole of the formed train and the phase detected by the position detector, at a phase which is obtained by correcting the phase detected by the position detector on the basis of a difference between the phase of a speed electromotive force of the whole of the formed train and the phase detected by the position detector, or at a phase which is detected by the position detector in conjunction with the position of a central car of the formed train.