Abstract: 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 %.

Abstract: The present invention provides: a process for treating a particulate water-absorbent resin, which enables to carry out pulverization stably in a process for producing a particulate water-absorbent resin, and transportation or storage of the particulate water-absorbent resin stably during or after producing the particulate water-absorbent resin, and to prevent contamination of cohered matters of the particulate water-absorbent resin; and involves no or little deterioration of properties. The process for treating a particulate water-absorbent resin is characterized by carrying out at least one selected from the group consisting of: (1) heating at least one portion of a surface getting contact with the particulate water-absorbent resin from the outside, (2) maintaining the temperature of at least one portion of a surface getting contact with the particulate water-absorbent resin at 30 to 150° C.

Abstract: The present invention provides a production process to obtain a hydrophilic polymer, having a low residual monomer content, with good productivity while keeping the properties of a hydrogel polymer resultant from polymerization. In a drying process for a hydrogel polymer, the hydrogel polymer is dried under normal pressure at a material temperature of not higher than 90° C. until the water content of the hydrogel polymer reduces to 15˜40 weight %, and then the hydrogel polymer is kept for not shorter than 10 minutes either in a state where the change of the water content of the hydrogel polymer is within 5 weight % and where the material temperature is in the range of 70˜120° C. or in a state where the water content of the hydrogel polymer is in the range of 15˜40 weight % and where the material temperature is in the range of 70˜120° C., and then the hydrogel polymer is finish-dried.

Abstract: A thermal storage agent used, for example, for air-conditioning systems of buildings, exhibiting excellent thermal storage, thermal conduction and safety, and a manufacturing method thereof. The thermal storage agent contains particulate oil gel bodies prepared by letting an oil absorbent resin absorb, and thus swell with, a thermal storage oil-soluble substance, wherein the oily gel bodies have a unitary volume of not less than 0.01 cm.sup.3 and are in contact with one another. A manufacturing method in accordance with the present invention can produce the thermal storage agent by letting an oil absorbent resin that is prepared by suspension polymerization in a solution containing the oil-soluble substance absorb, and thus swell with, the oil-soluble substance.

Abstract: A maleic acid-based copolymer is provided which has a weight-average molecular weight of 1,000 to 100,000, a calcium ion-capturability of 300 mgCaCO.sub.3 /g or higher calculated as calcium carbonate, and a clay-dispersibility of 1.2 or higher. Another maleic acid-based copolymer is also provided which has a level of adsorption to clay within the range of 20 to 90% and a calcium ion-stabilization degree constant of 4.0 or larger.

Abstract: A maleic acid-based copolymer is provided which has a weight-average molecular weight of 1,000 to 100,000, a calcium ion-capturability of 300 mgCaCO.sub.3 /g or higher calculated as calcium carbonate, and a clay-dispersibility of 1.2 or higher. Another maleic acid-based copolymer is also provided which has a level of adsorption to clay within the range of 20 to 90% and a calcium ion-stabilization degree constant of 4.0 or larger.

Abstract: A process for preparing an absorbent resin includes the steps of: preparing a first crosslinking agent (A) including at least two polymerizable unsaturated bonds; preparing a second crosslinking agent (B) including at least two polymerizable unsaturated bonds and hydroxyl groups; preparing a crosslinking agent including (A) and (B) with a ratio of (A) to (B) ranging from 95/5 to 50/50; and polymerizing a hydrophilic unsaturated monomer having at least one carboxyl group using the crosslinking agent. The crosslinking agent includes a crosslinking agent which includes a main component at least 90 percent by weight, the main component being an ester having at least two polymerizable unsaturated bonds, wherein the ester is composed of a polyhydroxy alcohol (C) having not more than six carbon atoms and at least three hydroxy groups, and an unsaturated carboxylic acid (D); and a molecular weight ratio of the main component to a standard compound (E) is in the range of from 0.7/1 to less than 1.

Abstract: An absorbent resin exhibiting a high absorption ratio, having only a small water-soluble component content, and have excellent gel stability to withstand the effect of aging is produced. The production of the absorbent resin comprises a step of polymerizing a water-soluble monoethylenically unsaturated monomer by using, in a proportion of 0.01-0.3 mol % based on the amount of the water-soluble monoethylenically unsaturated monomer, a cross-linking agent having at least one group of the following formula I: ##STR1## wherein R.sup.1 is an alkylene group of 2 to 4 carbon atoms interposed between two polymerizing unsaturated groups in the molecular unit thereof and then heat-treating the resin produced by the polymerization at a temperature in the range of from 160.degree. to 230.degree. C.

Abstract: A method for the production of an absorbent resin, which method comprises mixing 100 parts by weight of (A) a hydrated gel of absorbent resin which is resulted from aqueous solution polymerization having a polymerization ratio in the range of from 60 to 99%, an average particle diameter in the range of from 0.1 to 200 mm, a water content in the range of from 30 to 90% by weight, and a temperature in the range of from 40.degree. to 110.degree. C., with from 1 to 50 parts by weight of (B) a substantially dry fine absorbent resin powder having an average particle diameter smaller than the average particle diameter assumed by said hydrated gel of absorbent resin (A) while in a dried state, then raising the polymerization ratio of said hydrated gel of absorbent resin (A) to a level higher than the polymerization ratio of said hydrated gel when being mixed.

Abstract: This invention provides a drilling fluid containing additives composed of copolymers which are obtainable by an industrially favorable process and superior in heat-resisting property. Even though the additives are used in a relatively small amount, such an amount sufficiently prevents changes in the properties of drilling fluid due to various kinds of hard water components being contained in underground water or cement as well as due to sea water, and the additives are able to display the properties of drilling fluid constantly regardless of presence or absence of salts.Drilling fluid additives of the present invention are composed of a water-soluble copolymer (A) having an average molecular weight of 1,000-50,000. The water soluble copolymer (A) is composed of 40-99.5 mole percent of an unsaturated carboxylic acid monomer (I), as shown in the following general formula (I), and 0.5-60 mole percent of an unsaturated (meth)allylether monomer (II), as shown in the general formula (II).

Abstract: Continuous agglomeration of an absorbent resin powder is accomplished by a method which comprises introducing the absorbent resin powder into a cylindrical member having an open lower end by means of a current of air through a dispersing member disposed in the upper part of the cylindrical member and, at the same time, spraying minute droplets of an aqueous liquid downwardly through a nozzle disposed inside the dispersing member thereby establishing mutual parallel flow contact between the absorbent resin powder descending toward the lower part of the cylindrical member as dispersed with the current of air and the liquid droplets descending toward the lower part of the cylindrical member as diffused in the radial direction, and removing the produced agglomerate having a plurality of particles of the absorbent resin powder cohesively united through the medium of the liquid droplets via the lower part of the cylindrical member. An apparatus for working the method is also disclosed.

Abstract: A method for the production of an acrylate by the neutralization reaction of acrylic acid and a basic substance, comprising sequentially (A) a step of supplying acrylic acid and said basic substance to water thereby subjecting them to a neutralization reaction while constantly retaining the neutralization ratio of acrylic acid within the neutralization reaction system in the range of 75 to 100 mol %, (B) a step of adjusting the neutralization ratio of acrylic acid within said neutralization reaction system in the range of 100.1 to 110 mol % by supplying said basic substance to said neutralization reaction system, (C) a step of retaining the neutralization ratio of acrylic acid within said neutralization reaction system in the range of 100.

Abstract: The invention provides biodegradable crosslinked polymers, which have a chelating effect and a dispersing effect to disperse an oily substance and an inorganic substance hardly soluble in water and are excellent in dispersion into water. The crosslinked polymers comprise; an ingredient of molecular weight 5,000 or less in 50% by weight, a bond having at least one of a group (II) represented by the chemical formula --CO--O-- and a group (III) represented by the chemical formula --CO--NH-- as a composition unit between main chains having a water-soluble oligomer structure having the functional group (I) represented by the general formula --COOM (here, M denotes anyone of a hydrogen atom, monovalent metal, divalent metal, trivalent metal, an ammonium group and organic amine group.), and showing a viscosity of 1,000 cP or less at 20.degree. C. by a 20% by weight aqueous solution of the crosslinked polymer.

Abstract: A water-absorbent resin having high absorption capacity and a slight amount of water-soluble ingredients is produced by a process, which includes polymerizing a water-soluble monoethylenic unsaturated monomer in the presence of a crosslinking agent, and using a bifunctional compound represented by the following general formula 1 as the crosslinking agent; ##STR1## wherein R.sup.1 and R.sup.2 are a hydrogen atom or a methyl group independently, and --(X)-- is a divalent organic group combined in a straight chain type by an optional arrangement of a structural unit (A) of --(CO--CH.dbd.CH--CO--O).sub.L -- and l=1-5, a structural unit (B) of --(CH.sub.2 CH.sub.2 O).sub.m -- and m=2-100, and a structural unit (C) of --(R.sup.3 O).sub.n -- and n=0-20, in which R.sup.3 is a C.sub.3 -C.sub.4 alkylene.

Abstract: A method for the production of a particulate hydrated gel polymer, which includes heating a hydrated gel polymer possessed of a cross-linked structure to a temperature in the range of from 45.degree. to 90.degree. C. and extruding the resultant hot hydrated gel polymer through a perforated plate containing holes of a diameter in the range of from 6.5 to 18 mm and an absorbent resin which includes drying the resultant particulate hydrated gel polymer.

Abstract: A method for the production of a salt-resistant absorbent resin, which comprises subjecting an aqueous solution of at least one monomer component (A) selected from the group consisting of unsaturated carboxylic acids and salts thereof to aqueous solution polymerization in the presence of from 1 to 30 parts by weight, based on 100 parts by weight of said monomer component (A), of an absorbent resin (B).

Abstract: A method for the production of a particulate hydrogel polymer by the exposure of a hydrogel polymer possessing a cross-linked structure to shear force in a vessel thereby finely dividing said hydrogel polymer, which method comprises exerting shear force repeatedly on said hydrogel polymer while keeping said hydrogel polymer at a temperature in the range of from 40.degree. to 110.degree. C. under a mechanical pressure in the range of from 0.01 to 1.5 kg/cm.sup.2, and method for the production of an absorbent resin comprising drying the resultant particulate hydrogel polymer.

Abstract: An absorbent resin is produced by a method which comprises adding to 100 parts by weight of an absorbent resin powder an aqueous liquid containing 7 to 100 parts by weight of water and a reducing substance in the presence of 0.01 to 5 parts by weight of at least one additive selected from the group consisting of water-insoluble fine powders and surfactants. The absorbent resin thus produced excels in absorption properties and exhibits a low residual monomer content.

Abstract: A method for the production of an acrylate by the neutralization reaction of acrylic acid and a basic substance, comprising sequentially (A) a step of supplying acrylic acid and said basic substance to water thereby subjecting them to a neutralization reaction while constantly retaining the neutralization ratio of acrylic acid within the neutralization reaction system in the range of 75 to 100 mol %, (B) a step of adjusting the neutralization ratio of acrylic acid within said neutralization reaction system in the range of 100.1 to 110 mol % by supplying said basic substance to said neutralization reaction system, (C) a step of retaining the neutralization ratio of acrylic acid within said neutralization reaction system in the range of 100.

Abstract: The present invention relates to a process for producing an acid-type polymaleic acid and acid-type maleic acid copolymer and also to the usage of the acid-type polymaleic acid and acid-type maleic acid copolymer produced by this process.According to the process of the present invention, the acid-type polymaleic acid and acid-type maleic acid copolymer, which are superior as a water-treating agent and detergent additive, are produced by polymerization of acid-type monomers in an aqueous solution. The process is simple and yields a polymer having a low molecular weight and a narrow molecular-weight distribution. The process permits one to economically produce the acid-type polymaleic acid and acid-type maleic acid copolymer which has good quality and outstanding performance as a water-treating agent etc. Thus the invention is a great boon to the industrial field of water treatment.