Abstract: This invention provides an industrially advantageous method of regenerating a large quantity of contaminated gels by treating a contaminated gel which has become less active in separation performance with an aqueous solution of a metallic salt or ammonium salt of thiocyanic acid, nitric acid, or hydrogen iodide having a concentration of from 30 weight % to saturation, at a temperature between 50.degree. and 120.degree. C., thereby effectively removing contaminants in the interstices among the gel particles or contaminants on the active points.

Abstract: The present invention provides a process for producing acrylic fibers having excellent surface smoothness and a color development ratio not less than 105%, without generating numerous wrinkles peculiar to wet spinning. The process comprises wet-spinning an acrylonitrile polymer spinning solution of from 50.degree. to 70.degree. C. having a viscosity of from 40 to 200 poises at 30.degree. C., (a) with a spinning draft of from 0.05 to 0.2 in the case wherein the spinnerette orifice capillary length is 0.5 mm or less, and (b) with a spinning draft of from 0.13 to 2.0 in the case where the spinnerette orifice capillary length exceeds 0.5 mm; coagulating and water-washing the resulting fibers substantially without stretching; and thereafter wet-heat-stretching the fibers not less than 4 times in length at a temperature not lower than 80.degree. C.

Abstract: Acrylic fibers consisting of not more than 90 weight % of an acrylonitrile polymer and less than 10 weight % of a water-absorbing resin having a particular cross-linking density, particle diameter and degree of water-swellability, which are excellent in practical properties such as strength, elongation, color fastness, spinnability and water-absorption.

Abstract: A process for producing hollow acrylonitrilic separation membranes in fibrous form which comprises shaping a membranous product in hollow fibrous form from a solution of acrylonitrile polymer dissolved in formamide-containing dimethylformamide while maintaining the temperature of said polymer solution within a specified range and subjecting said membranous product to a solvent removal treatment under a specific condition, thereby producing an acrylonitrilic separation membrane which is asymmetric, porous in structure, and excellent both in separation ability and in mechanical strength.

Abstract: The present invention relates to aqueous microhydrogel dispersions composed of hydrogel particles not larger than 1.mu. dispersed stably in an aqueous medium, to processes for producing the same, and to processes for producing microhydrogel particles having particles diameters not larger than 1.mu.. Said aqueous microhydrogel dispersions exhibit an excellent water-swelling ability and can be used as property-modifiers for textile products and molded plastic articles; as water-absorbents; moisture-absorbents; soil-improving agents, etc.

Abstract: A process for producing a synthetic rush-like structure which comprises causing an acrylonitrile polymer composition in a substantially melted state (Polymer A or B or C) to flow down towards a spinning orifice; adjusting the pressure of the system in which the melt just before the orifice is present to within a specific range; extruding the melt to form a foamed product; and subjecting the foamed extrudate to heat treatment, thereby obtaining a synthetic rush-like structure resembling the natural rush plant in outer skin structure and internal structure and having excellent sensory and practical properties.

Abstract: In a process for producing an acrylonitrile polymer melt in a substantially melted state by polymerizing a monomer mixture containing acrylonitrile in the presence of water at elevated temperature under increased pressure, the polymerization is carried out continuously using a persulfate as the polymerization initiator and under a particular forced stirring as defined in the specification. This process effectively suppresses runaway polymerization reaction, facilitates the melting of the resulting polymer, and in addition produces in an industrially advantageous manner a melt of an acrylonitrile polymer having a moderate molecular weight.

Abstract: Acrylic synthetic fibers highly resistant to pilling and having good dyeability can be produced by specifying the composition of the acrylic polymer, the condition of the primary stretching step, the internal water content of the water-swollen gel fibers, the conditions of the steps of the drying-compacting, secondary stretching and relaxing heat treatment.

Abstract: In producing an aqueous emulsion containing substantially no emulsifier, an aqueous polymer emulsion remarkably elevated in chemical stability is obtained by copolymerizing a specific amount of a particular vinyl monomer containing polyoxyethylene units as an indispensable copolymerization component.

Abstract: Carbon fibers having excellent physical properties and satisfactory quality uniformity are produced in an industrially advantageous manner by heat-treating acrylonitrile filaments so prepared that a specified amount of the sulfonic acid groups (--SO.sub.3 H) which have been introduced into the fiber is converted to its salt form (--SO.sub.3 X) and that the degree of filament separability of the spun fiber-bundle traveling through the heat stretching step is maintained within a specified range.

Abstract: A stable aqueous emulsion of an acrylonitrile polymer which comprises a dispersion system of said acrylonitrile polymer having a particle size of substantially less than 1.mu. in water and contains substantially no emulsifying agent nor dispersing agent. Said emulsion is produced by a process comprising; polymerizing acrylonitrile alone or in a monomer mixture comprising more than 60% by weight of acrylonitrile and as another component, at least one other ethylenically unsaturated compound, under stirring at a temperature higher than 120.degree. C and at least autogenous pressure, in an aqueous system consisting essentially of water in an amount of 45 to 95% by weight based on the total weight of water and monomer(s), to thereby introduce at least 2.times.10.sup.

Abstract: A method of treating carbon fibers in which carbon fibers are supplied into a solution of an electrolyte containing a vinyl monomer, and the carbon fibers are caused to act as the cathode to produce electrolytic reaction in said solution so that the surfaces of the carbon fibers are covered with a polymerization product whereby the ability of the carbon fibers to bundle themselves can be elevated and the adhesiveness between the carbon fibers and resin to be reinforced upon producing carbon fiber composite materials can be improved.

Abstract: Carbon fibers are prepared by spinning a copolymer of a carboxyl group-containing unsaturated monomer and at least 85 mol% acrylonitrile, washing the filaments with water, stretching the filaments in hot acid water having a pH below 3.5, and heating the resultant fibers to cause carbonization or graphitization.

Abstract: An acrylonitrile polymer composition obtained by uniformly mixing an acrylonitrile polymer, water and acrylonitrile is heated at the autogeneous pressure or above and the resulting melt is shaped into a desired form. The shaping processability is improved thereby.

Abstract: Process for the production of a stable polymer emulsion by polymerizing a radical-polymerizable monomer having an unsaturated bond in the presence of a water-soluble polymer containing monomer units consisting essentially of an ethylenically unsaturated carboxylic acid or salts thereof, and an ethylenically unsaturated sulfonic acid or a salt thereof and an anionic surface active agent. This polymerization takes place in an aqueous medium at a pH not higher than 4 in the presence of a water-soluble catalyst. The polymer emulsion of the present invention is much more stable chemically and mechanically than conventional polymer emulsions and the polymers produced by applicants' process have an extremely small particle size making the emulsions immediately suitable for a variety of purposes.

Abstract: Process for producing a flame retardant acrylic fiber by wet-spinning a halogen-containing acrylic spinning solution containing antimony oxide particles dispersed therein, wherein an acrylic fiber having a high degree of flame retardancy and improved fiber properties, such as transparency, luster and brightness of colors of dyed products, is produced in an industrially advantageous manner by regulating the water content in the hydrogel fiber obtained by hot stretching after wet-spinning within a range of 50-130% based on the fiber-forming polymer.

Abstract: The invention provides an adsorbent suitable for column packing which is composed of a granular material obtained by subjecting a mixture of an activated sludge-containing material and a primary condensate of a formaldehyde type resin and/or a dialdehyde compound to heat-curing and granulating. The adsorbent can advantageously be used to treat industrial waste water containing ionic or nonionic water pollutants such as heavy metal ions, dyes, surfactants, high molecular weight coagulants and mineral oils.

Abstract: The present invention relates to a process for producing an adsorbent for the treatment of waste water, suitable for column packing, which is composed of a granular material obtained by subjecting an aqueous mixture of an activated sludge-containing material and the water-soluble primary condensate of a formaldehyde-type resin and/or an aldehyde compound to a curing treatment with an acid catalyst and a granulating operation. The adsorbent can advantageously be used in disposing of industrial waste water containing ionic or nonionic water pollutants such as heavy metal ions, dyes, surfactants, high molecular weight coagulants and mineral oils.

Abstract: A process for producing carbon fibers by heat-treating an acrylonitrile fiber, containing or impreganted with an aminosiloxane, at a temperature of at least 150.degree. C for 0.1 second to 30 minutes so that the fiber contains 20 to 80 weight % undissolved matter upon immersing it in a 60% aqueous solution of sodium thiocyanate at 80.degree. C for 20 minutes, and then carbonizing the fiber, whereby the productivity throughout the whole process, including the step of producing the precursor fiber and the step of producing the carbon fiber, is increased and a carbon fiber having high tensile strength and high modulus of elasticity is obtained in an industrially advantageous manner.

Abstract: An improved process for producing an acrylonitrile melt by polymerizing acrylonitrile alone or a monomer mixture consisting of at least 75% of acrylonitrile and as the remainder at least one different ethylenically unsaturated compound in a system where water is present in an amount from 3 to 80% by weight based on the total amount of the monomer(s) and water, under a pressure above the self-generated pressure at a temperature above 80.degree. C. The improvement is characterized by the use of hydrogen peroxide as the polymerization initiator.