In a production process for a water-absorbent resin, comprising the steps of: blending a liquid material and a water-absorbent resin; and heating the resultant mixture in order to produce a modified water-absorbent resin, the present invention is to provide: a method for uniformly and efficiently treating a water-absorbent resin favorably in view of industry, and as a result, a good-balanced water-absorbent resin having various excellent properties, such absorption capacity without a load, absorption capacity under a load, and single-layer absorption capacity under a load in contact with an aqueous liquid. The production process comprises the step of spray-blending a water-absorbent resin (A) and a liquid material (B) with a blending apparatus equipped with a spray nozzle (C), wherein the liquid material (B) is sprayed from the spray nozzle (C) and its spray pattern is a circular and hollow cone shape or a double-convex-lens and elliptic cone shape. In addition, the production process comprises the step of heat-treating a water-absorbent resin under an atmosphere having a dew point of not higher than 60° C. and a temperature of not lower than 90° C., wherein the water-absorbent resin is obtained after a drying step following a pulverization step.

Water-absorbent resin and production process therefor

The invention concerns a process for producing water-insoluble water-absorbing resins, which comprises the steps of initiating polymerization of an aqueous solution containing 30 to 80% by weight of (a) a hydrophilic vinyl monomer having a functional group and (b) a crosslinking agent by supplying the aqueous solution together with (c) a polymerization initiator to a polymerizing apparatus capable of heating and/or cooling surfaces in contact with the aqueous solution, subsequently causing constant temperature polymerization of the solution without agitating the same by controlling the temperature of the system being polymerized to 20° to 70° C., and elevating, if necessary, the temperature ok the system to be in excess of 70° C. in a stage with a polymerization percentage of 70% or above before completion of polymerization. Obtainable water-insoluble water-absorbing resins have excellent water-absorbing property and have less water-soluble components. Thus, the water-absorbing resins according to the invention are useful for physiological commodities, paper diapers or like sanitary materials, drip absorbing materials, cold water retainers, dew condensation prevention materials for construction materials and so forth.

Process for producing water-absorbing resins

The present invention provides a production process by which a water-absorbent resin of excellent quality can be obtained at a low cost by reasonable steps in aqueous solution polymerization. The process for producing a water-absorbent resin comprises the step of polymerizing an aqueous solution of water-absorbent resin-forming monomers including acrylic acid and/or its sodium salt as major components, wherein: (1) the aqueous solution has a monomer component concentration of not less than 45 weight %; (2) the polymerization is carried out while water is evaporated so that the ratio (concentration ratio) between a solid component concentration in a hydropolymer as formed by the polymerization and a solid component concentration in the aqueous monomer solution will not be less than 1.10; and (3) the solid component concentration in the hydropolymer as formed by the polymerization is not more than 80 weight %.

Water-absorbent resin, hydropolymer, process for producing them, and uses of them

An organic EL element, wherein a leak prevention layer having a resistance increased according to the rise of temperature is installed in an organic EL layer held between an anode and a cathode and emitting light, whereby the anode and cathode can be prevented from being short-circuited due to dielectric breakdown.

Organic el element

An inorganic coating film having improved water repellency is provided. The improved surface is provided by treating an inorganic coating film with a material that is reached or adsorbed on the surface of the inorganic coat to increase water repellency. The inorganic coating to be treated may be a silicon dioxide film. The materials used to treat the film include: (1) halogenated silane compounds; (2) silane compounds having a structure including at least one bond selected from Si--H, Si--OH, Si--OR, Si--SH and Si--SR, wherein R is an organic group; (3) silane compounds having a structure including at least one of ##STR1## wherein R1, R2 and R3 are hydrogen or an organic group and (4) reactive organic compounds having a fluorine substituting group, hydrogen fluoride or a metal fluoride.

Synthetic resin ophthalmic lens having an inorganic coating

PURPOSE: After the reverse-phase suspension polymerization of unsaturated carboxylic acid, water is removed from the resultant polymer slurry by azeotripic distillation with an organic solvent to produce granular hydrogel of a specific water content scarcely showing tackiness. CONSTITUTION: The water-in-oil type reverse-phase polymerization of (A) an α,β- unsaturated carboxylic acid/or its alkali metal salt, preferably acrylic acid is carried out in the presence of (B) a dispersing agent and a crosslinking agent such as ethylene glycol, then water is removed from the polymer slurry by azeotropic distillation with (C) an organic solvent, preferably hexane until the water content comes down to 10W43wt%. Further, the remaining water is removed by drying to give the objective hydrogel. EFFECT: The stages of the production process are reduced to increase its productivity and permit the economical production of the hydrogel. COPYRIGHT: (C)1982,JPO&Japio

Production of hydrogel

PURPOSE: To produce the titled polymeric material having a small particle diameter and a high water absorption rate, by subjecting an α,β-unsaturated carboxylic acid monomer (metal salt) to a water-in-oil reversed phase suspension polymerization in the presence of a specified dispersant. CONSTITUTION: A highly water-absorbing polymeric material, average particle diameter 1W40μ, is prepared by adding an organic solvent (e.g., n-hexane) to an aqueous solution, concentration 5W40wt%, containing an α,β-unsaturated carboxylic acid monomer[e.g., (meth)acrylic acid) and/or its metal salt so that the ratio of solvent to aqueous monomer solution is 1:1W4, adding further, to the resulting solution, 0.1W20wt%, based on organic solvent, nonionic surfactant, HLB6W9, (e.g., sorbitan monolaurate) as a dispersant and 0W10wt%, based on monomer, crosslinking agent (e.g., diallyl phthalate) and subjecting the final solution to a water-in-oil reversed phase suspension polymerization at 200°C in the presence of a radical polymerization initiator. COPYRIGHT: (C)1982,JPO&Japio

Production of highly water-absorbing polymeric material having improved water-absorption rate

PURPOSE: To obtain the titled material useful for the preparation of a variety of water-absorbing materials, by subjecting an α,β-unsatuated carboxylic acid to a W/O type reversed phase suspension polymerization in the presence of a crosslinking agent by using, a carboxyl group-containing polymer having affinity for organic solvents as a dispersant. CONSTITUTION: In subjecting an α,β-unsaturated carboxylic acid monomer or/ and its alkali metal salt, e.g., (meth)acrylic acid (sodium salt), to a W/O type reversed phase suspension polymerization in the presence of a crosslinking agent, e.g., ethylene glycol di(meth)acrylate; a high-molecular material having excellent water absorbability is prepared by using, as a dispersant, a carboxyl group-containing polymer having an affinity for organic solvents (e.g., n-hexane or xylene), e.g., a methacrylic acid/methyl methacrylate/2-ethylhexyl acrylate copolymer. This high-water-absorbing hydrogel is transparent, less colored and almost nontoxic and can be used in sanitary materials, agents for separating water from oil, dehydrating or drying agent, water retaining agent for soil, etc. COPYRIGHT: (C)1982,JPO&Japio

Productin of high-molecular material having excellent water absorbability

PURPOSE: To produce a heat-treated polyimide having high electrical conductivity, and capable of being graphitized easily while keeping its shape, by heat-treating an aromatic polyimide in an inert atmosphere at a specific temperature. CONSTITUTION: Preferably a film or fiber of an aromatic polyimide [preferably poly-N,N'-(p,p'-hydroxydiphenylene)pyromellitic imide] is heat-treated in an inert atmosphere at 2,000W3,500°C to obtain the objective heat-treated product. A composition having further improved electrical conductivity can be produced by doping the heat-treated product with an electron acceptor or an electron donor. COPYRIGHT: (C)1985,JPO&Japio

Production of heat-treated polyimide having high electrical conductivity, and its composition

PURPOSE: To obtain the titled substance, having improved water absorbing property particularly on the alkalin side, and suitable for sanitary articles, by copolymerizing a monomer component consisting of a water-soluble salt of (meth)acrylic acid and methacrylic or acrylic acid in a specific proportion in the presence of a crosslinking agent in an aqueous medium. CONSTITUTION: A suspension containing (A) a monomer component consisting of a water-soluble salt of (meth)acrylic acid and methacrylic acid or acrylic acid at a weight ratio of 98W10:2W90, preferably 95W40:5W60 in an amount of at least 70wt% or more based on the total comonomer, (B) 0.01W1wt%, preferably 0.01W 0.5wt%, crosslinking agent having two or more reactive groups copolymerizable with the component (A), e.g. ethylene glycol diacrylate, and (C) a catalyst, e.g. ammonium persulfate, is polymerized by spraying in an inert gaseous medium at 100W250°C to give the aimed hydrogel having reversible absorption and release of water with a pH of water and no toxicity. USE: A separating agent, drying agent, water retaining agent, etc. for water in oil. COPYRIGHT: (C)1981,JPO&Japio

Toshihiro Onishi

Papers

Production of hydrogel

Production of highly water-absorbing polymeric material having improved water-absorption rate

Productin of high-molecular material having excellent water absorbability

Production of heat-treated polyimide having high electrical conductivity, and its composition

Highly water absorbing hydrogel and its preparation