Abstract: There is described a method of making a styrene-type polymer composition which comprises a step of suspension polymerizing a styrene-type monomer composition in an aqueous medium comprising water, polyvinyl alcohol and a water-soluble sulfonated polystyrene, a water-soluble sulfonated styrene-maleic anhydride copolymer or a mixture thereof. Optionally, the styrene-type monomer composition may contain a rubbery material as a toughening agent. Optionally, the suspension polymerization step may be conducted subsequent to a prepolymerization step conducted in mass.

Abstract: Latex adhesives having a Tg of -60.degree. to 0.degree.C. characterized by superior rheological properties, are prepared without the use of additional thickeners from a colloid stabilized latex comprising: 65-90% by weight of the latex polymer solids of an acrylate or methacrylate ester monomer polymerized in 10-35% by weight of the latex solids of a polymeric colloid, the polymeric colloid having a Tg of -40.degree. to 0.degree.C., a number average molecular weight of 2,000 to 10,000 and comprising(a) 50 to 85% by weight of a monomer of the formula: ##STR1## where R' is hydrogen or methyl and R" is a C.sub.1 -C.sub.12 straight or branched chain alkyl group;(b) 10 to 50% by weight of an ethylenically unsaturated mono- or dicarboxylic acid;(c) 5 to 30% by weight of an acrylic or methacrylic ester of a polyalkylene oxide, and(d) 0 to 30% by weight of another ethylenically unsaturated copolymerizable monomer.

Abstract: Highly uniform polymeric microbeads of a predetermined size, preferably having an attached fluorescent label on the surface, are prepared by causing seed particles to swell by absorption of a plurality of low molecular weight substances, at least one of which is a monomer having a reactive functional group. After absorption, the monomer is internally polymerized, and the reactive functional group is preferably reacted with a polyfunctional spacing agent thereby to provide a second reactive functional group. The latter is then reacted with a fluorescent label to provide the labeled microbead.

Abstract: Highly uniform polymeric microbeads of a predetermined size, preferably having an attached fluorescent label on the surface, are prepared by causing seed particles to swell by absorption of a plurality of low molecular weight substances, at least one of which is a monomer having a reactive functional group. After absorption, the monomer is internally polymerized, and the reactive functional group is preferably reacted with a polyfunctional spacing agent thereby to provide a second reactive functional group. The latter is then reacted with a fluorescent label to provide the labeled microbead.

Abstract: Highly uniform polymeric microbeads of a predetermined size, preferably having an attached fluorescent label on the surface, are prepared by causing seed particles to swell by absorption of a plurality of low molecular weight substances, at least one of which is a monomer having a reactive functional group. After absorption, the monomer is internally polymerized, and the reactive functional group is preferably reacted with a polyfunctional spacing agent thereby to provide a second reactive functional group. The latter is then reacted with a fluorescent label to provide the labeled microbead.

Abstract: A copolymer emulsion for bonding nonwoven products comprising an aqueous medium having colloidally dispersed therein a copolymer consisting essentially of vinyl acetate, 5-35 wt % ethylene and 2 to 10 wt % of an amide functional crosslinking comonomer which is N-methylolacrylamide or a compound of the formula R--NH--(CH.sub.2).sub.n --CH(OR').sub.2 where R is (meth)acryloyl, R' is a C.sub.1 -C.sub.4 alkyl group and n is 3 or 4, the copolymer emulsion prepared in the presence of 0.1 to 1 wt % polyvinyl pyrrolidone, based on vinyl acetate in the copolymer. Such emulsion binder copolymers demonstrate improved solvent resistance.

Abstract: The invention provides an improvement in the suspension polymerization of vinyl chloride or a monomer mixture mainly composed of vinyl chloride in an aqueous medium containing a nonionic surface active agent and in the presence of a monomer-soluble polymerization initiator, according to which the aqueous polymerization medium is admixed with a crosslinked copolymer having carboxyl groups such as a copolymer of acrylic acid and diethyleneglycol bisallyl or bismethallyl ether at a moment when the percentage of the monomer conversion is in the range from 1 to 20% so that a polyvinyl chloride resin product of high quality can be obtained having an outstandingly high bulk density and plasticizer absorptivity but still containing an extremely small number of fish eyes.

Abstract: The invention provides an improvement in the suspension polymerization of vinyl chloride in an aqueous medium in the presence of a monomer-soluble polymerization initiator, according to which the amount of polymer scale deposition on the reactor walls can be greatly decreased. The improvement comprises admixing the aqueous polymerization medium with (a) a water-soluble crosslinked copolymer of an unsaturated carboxylic acid monomer, e.g. acrylic acid, and a crosslinking monomer such as di(methyl)allyl ether of diethyleneglycol and (b) a non-ionic surface active agent in combination.

Abstract: A process for preparing large-sized polymer particles having a particle diameter in a range of 0.1 to 500 .mu.m by seeded polymerization is described, comprising:finely dispersing a polymerizable monomer in an aqueous medium to prepare a monomer dispersion in which a number average particle diameter of the resulting monomer droplets is not larger than that of seed particles, and a number average particle diameter in a semi-stable condition (Dm) of the monomer droplets satisfies, with a desired number average particle diameter of the final polymer particle as D, the following relation:0.5.times.D<Dm<3.5.times.Dcombining said monomer dispersion with a dispersion of seed particles to make the polymerizable monomer absorbed or adsorbed on the seed particles; andpolymerizing the polymerizable monomer in the presence of a polymerization initiator.

Abstract: An improved process is provided for producing porous PVC resin particles by a thickened aqueous suspension polymerization process comprising polymerizing vinyl chloride monomer in an aqueous suspension wherein said aqueous medium contains at least one dispersant capable of thickening water, and optionally at least one secondary surfactant, at least one oil-soluble free radical generating catalyst, the improvement comprising charging said free radical catalyst as a solution wherein the solvent for said catalyst solution has a density equal to or less than that of the monomer being polymerized and the catalyst solution has a density less than water.

Abstract: Latex adhesives having a Tg of -60.degree. to 0.degree. C. characterized by superior rheological properties, are prepared without the use of additional thickeners from a colloid stabilized latex comprising: 65-90% by weight of the latex polymer solids of an acrylate or methacrylate ester monomer polymerized in 10-35% by weight of the latex solids of a polymeric colloid, the polymeric colloid having a Tg of -40.degree. to 0.degree. C., a number average molecular weight of 2,000 to 10,000 and comprising(a) 50 to 85% by weight of a monomer of the formula: ##STR1## where R' is hydrogen or methyl and R" is a C.sub.1 -C.sub.12 straight or branched chain alkyl group;(b) 10 to 50% by weight of an ethylenically unsaturated mono- or dicarboxylic acid;(c) 5 to 30% by weight of an acrylic or methacrylic ester of a polyalkylene oxide, and(d) 0 to 30% by weight of another ethylenically unsaturated copolymerizable monomer.

Abstract: What are disclosed are concentrated emulsions of an olefin copolymer in a liquid carrier medium which does not dissolve the copolymer and, as an emulsifier, a graft or block copolymer of the formulaA--Y,wherein A represents a sequence or segment of an olefin copolymer, of hydrogenated polyisoprene, or of an hydrogenated butadiene/isoprene copolymer, and Y represents a sequence or segment, formed by the polymerization of vinyl monomers which essentially are not of the acrylate or methacrylate type, which is soluble in the carrier medium, as well as methods for making the same.

Abstract: A process for the production of polymers of vinyl chloride by suspension polymerization, uses as the suspension stabilizer either(A) a methylhydroxypropylcellulose with a methoxy substitution degree of 20-32%, a hydroxypropoxy substitution degree of 2-10%, and a viscosity of 30-70 mPa.s; and/or(B) a suspension agent combination consisting essentially of:(a) methylcellulose with a methoxy substitution degree of 22-34% and a viscosity of 7-20 mPa.s, and(b) methylcellulose with a methoxy substitution degree of 22-34% and a viscosity of 50 mPa.s-4,000 mPa.s and/or methylhydroxypropylcellulose with a methoxy substitution degree of 20-32%, a hydroxypropoxy substitution degree of 2-10%, and a viscosity of 100-3,000 mPa.s,and polymerizes in the presence of 0.4-8% by weight of an ethylene-vinyl acetate copolymer. The resultant polymers are suitable for lowering viscosity of polyvinyl chloride plastisols.

Abstract: A repeatedly usable and releasable sheet is coated thereon with an adhesive copolymer microspheres-containing aqueous suspension and polymer microparticles prepared by polymerization of one or more vinyl monomers. In the presence of a protective colloid comprising casein, the microspheres is prepared by aqueous suspension polymerization of (a) from 70 to 99.9 percent by weight of one or more monomers selected from the group consisting of alkyl acrylate esters and alkyl methacrylate esters, (b) from 0.1 to 10 percent by weight of one or more .alpha.-monoolefin carboxylic acids and (c) from 0 to 29.9 percent by weight of one or more vinyl monomers other than the foregoing (a) and (b).

Abstract: A method is disclosed for controlling the activity of or deactivating a transition element olefin polymerization catalyst by contacting the catalyst with a deactivating polymer comprising a homopolymer of an unsaturated polar organic compound or a copolymer of an alpha-olefin and an unsaturated polar organic compound.

Abstract: Poly(methylmethacrylate) polymer particles of substantially increased average particle diameter are prepared by suspension polymerization in a medium comprising an alkane and a chlorinated hydrocarbon, e.g. carbon tetrachloride, in relative proportions chosen so as to provide buoyancy to the polymer particles so formed.

Abstract: A suspension of an aqueous solution of a water-soluble polymer in an organic liquid forming a continuous organic phase, said suspension containing, as an emulsifier, a mixture of two copolymers which are similar but differ in their content of basic nitrogen by 0.1 to 1.5 percentage points.

Abstract: The aerobically hardenable compositions which comprise polymerizable systems containing components having some degree of ethylenic unsaturation and an oxygen-stable polymerization initiator of at least one organo-boron compound containing at least a major portion of boron to carbon bonds and possibly some boron to hydrogen bonds in the molecule and the boron containing radials are bound to an organic polymer matrix which is oxygen stable, the compositions being useful as casting resins, fillers and adhesives.

Abstract: The present invention comprises a method of preparing vinyl chloride polymers or vinyl chloride copolymers suitable for the preparation of plastisols. The method can be used at polymerizations, wherein a pre-emulsion of a substance having a very low solubility in water, is caused to swell by the vinyl chloride monomer, whereafter the monomer emulsion obtained is subjected to polymerizing conditions. According to the invention the emulsion is stabilized, and, by polymerizing in the presence of an stabilizing latex, it is possible to avoid, that the obtained latex becomes instable. In this way it is possible to prepare polymers having a particle size and a particle size distribution giving a product with low viscosity at the preparation of plastisols.

Abstract: What are disclosed are concentrated emulsions of an olefin copolymer in a liquid carrier medium which does not dissolve the copolymer and, as an emulsifier, a graft or block copolymer of the formulaA--Y,wherein A represents a sequence or segment of an olefin copolymer, of hydrogenated polyisoprene, or of an hydrogenated butadiene/isoprene copolymer, and Y represents a sequence or segment, formed by the polymerization of vinyl monomers which essentially are not of the acrylate or methacrylate type, which is soluble in the carrier medium, as well as methods for making the same.

Abstract: Products formed from chlorosulfonyl isocyanate either by sequentially reaction of a hydroxy functional compound followed by reaction of the sulfonyl chloride group with a primary or secondary amine, or by reaction of chlorosulfonyl isocyanate with an excess of primary or secondary amine, are cure accelerators for acrylic compositions. Depending on the choice of alcohol or amine, the accelerator may be functionalized so that it is bound or bindable to an organic or silicone polymer backbone or contains other desirable functionality such as peroxy, photosensitizer, or acrylic groups.

Abstract: An ungelled polymeric reaction product having a number average molecular weight of up to about 3000 and having a polydispersity of within 1.2 to 2.5 is prepared by a process involving the vinyl addition polymerization of a vinyl monomer component. At least 30 percent by weight of the vinyl monomer component is an active hydrogen-containing vinyl monomer, and the polymerization is conducted in the presence of an active hydrogen-containing polymer having a number average molecular weight of less than 3000.

Abstract: A process for producing toner, which comprises dispersing a monomer system comprising a polymerizable monomer and a polar polymer in a dispersion medium containing a dispersant having a charging polarity opposite to that of said polar polymer, and subjecting said monomer system to the suspension polymerization. By this process, toner particles excellent in fixing characteristic, developing characteristic and abrasion resistance can be obtained with a narrow particle size distribution.

Abstract: The invention relates to bead polymers based on vinylene carbonate which are distinguished, in particular, by high porosity and which are well suited as carrier materials for biologically active substances.The preparation of these bead polymers is carried out, according to the invention, in the presence of certain dispersion stabilizers.

Abstract: A process for producing vinyl chloride polymers and copolymers by suspension polymerization is carried out in the presence of small amounts of ethylene/vinyl acetate copolymers with a vinyl acetate content of 38% by weight to 55% by weight and with a viscosity number of 95-210 ml/g, the catalyst being added to the polymerization charge in dissolved form. The resultant polymers are suitable for lowering the viscosity of polyvinyl chloride plastisols.

Abstract: Sterically stabilized aqueous polymer dispersions free from charged species are made by emulsifying in water ethylenically unsaturated monomer(s), soluble in water to the extent of 0.08%-8% by weight but giving rise to a polymer which is insoluble, and polymerizing the monomer(s) in that state in the presence of (a) a non-ionizable azo initiator which is water-soluble and substantially monomer-insoluble and (b) a block or graft copolymer stabilizer of specified structure.

Abstract: An azo polymerization initiator composition obtained by kneading an azo compound, a dispersing agent and a surface active agent at a temperature of 20.degree. C. or lower, while adjusting the water content of the composition to 0 to 50% by weight, has good storage stability for a long period of time and, at any time desired for polymerization, can give a uniform aqueous suspension of the azo compound for polymerization of unsaturated vinyl monomers with high polymerization initiator activity.

Abstract: Vinyl chloride polymers and copolymers are produced by suspension polymerization in the presence of a small amount of specific ethylene-vinyl acetate copolymers. The catalysts, the ethylene-vinyl acetate copolymer, and the monomer or monomer mixture are added to the polymerization charge before the suspension agent. The resultant polyvinyl chloride is especially suitable for lowering the viscosity of polyvinyl chloride plastisols.

Abstract: A method of producing a conjugated diene polymer comprising polymerizing monomers comprising at least one conjugated diene hydrocarbon under solution polymerization conditions such that substantially all of said monomers are polymerized, terminating the thus formed polymer to deactivate substantially all of the active polymer lithium, and then polymerizing additional portions of said monomers in solution with at least a portion of the terminated polymer under conditions such that substantially all of said additional monomers are polymerized.

Abstract: Cyanoacrylate adhesive compositions containing a tannin, e.g., digallic acid, tannic acid, or other hydrolyzable or condensed tannin. The inclusion of tannin increases adhesion and heat resistance of the cured adhesive on metal substrates.

Abstract: A nonaqueous dispersion polymerization process can offer many distinct advantages over other polymerization techniques including: improved heat transfer, increased production capacity, and energy savings. This invention discloses a process for the nonaqueous dispersion polymerization of butadiene monomer in a reaction mixture containing a liquid nonaqueous dispersion medium, the improvement which comprises carrying out the polymerization of the butadiene monomer in the presence of random copolymers of butadiene and isoprene, to produce very high cis-1,4-polybutadiene.

Abstract: A stable aqueous suspension containing an organic azo compound as polymerization initiator in fine particles, containing substantially no organic solvent and containing no foam which damages dispersing stability of the aqueous suspension and retards polymerization rate can be formed by dissolving an organic azo compound in an organic solvent, emulsifying the resulting solution by adding water and a dispersing agent A and a dispersing agent B thereto with stirring, and removing the organic solvent from the emulsified liquid preferably under reduced pressure.

Abstract: The production of polymer beads from vinyl aromatic monomers, using an inorganic phosphate aqueous suspension polymerization process is effected with the addition of 0.0001 to 0.004 percent by weight of a polystyrenesulfonate with the production of beads having a narrow bead size distribution. In addition to the improved bead size distribution, large beads can be produced which retain their sphericity.

Abstract: Extremely strong, i.e., non-friable TiCl.sub.3 Ziegler-type polymerization catalyst are obtained by prepolymerizing a reduced solid TiCl.sub.3 product with a mixture of propylene and linear C.sub.8 -C.sub.18 alpha-olefin to produce a reduced solid TiCl.sub.3 product containing 5 to 35 weight percent of a copolymer of propylene and C.sub.8 -C.sub.18 alpha-olefin having a ratio of the infrared spectrum of the copolymer at 720 cm.sup.-1 : the infrared spectrum of the copolymer at 975 cm.sup.-1 in the range of 0.04 to 0.20.

Abstract: Production of suspension polyvinyl chloride suitable for reducing the viscosity of polyvinyl chloride plastisols is effected by suspension polymerization in the presence of small amounts of(a) an ethylene/propylene/ethylidene norbornene terpolymer having a propylene content of 40-50% by weight, with 5-15 double bonds per 1,000 carbon atoms and with a viscosity of 4-20 mPa s, measured with 2% solutions in trichloroethylene at 25.degree. C.;and/or(b) a polyvinyl isobutyl ether having a K value of 80-150, measured with 0.5% solutions in isooctane at 20.degree. C., wherein the catalysts, the ethylene/propylene/ethylidene norbornene terpolymer and/or the polyvinyl isobutyl ether and the monomer or comonomer mixture are added to the polymerization batch before adding the suspension agent or the suspension agent mixture. These suspension polymers are used as additives for polyvinyl chloride plastisols.

Abstract: An emulsifier useful for preparing an aqueous emulsion having a high viscosity which comprises a copolymer of (1) at least one monomer selected from a vinyl ester, vinyl alcohol, an alkyl acrylate and an alkyl methacrylate and (2) at least one monomer selected from an acrylic acid derivative of the general formula:CH.sub.2 .dbd.CR.sup.1 --CO--A--R.sup.2 --SO.sub.3 Mand a maleic acid derivative of the general formula: ##STR1## wherein R.sup.1 is hydrogen or methyl group, R.sup.2 is an alkylene group, R.sup.3 is hydrogen, an alkyl group or an alkali metal, M is hydrogen or an alkali metal, and A is --O-- or --NR-- in which R is hydrogen, an alkyl group or --R.sup.2 SO.sub.3 M. Emulsions prepared by employing the above copolymer as emulsifier have very high viscosities and moreover excellent storage, freeze-thaw and dilution stabilities.

Abstract: A process for producing a vinyl chloride polymer which comprises polymerizing vinyl chloride monomer or a mixture of it with another monomer copolymerizable therewith in an aqueous medium or in bulk, characterized in that the inside of the polymerization reactor is coated beforehand with the product of reaction of an oily or waxy cyclopentadiene polymer and a phenolic compound with or without an aldehyde compound.

Abstract: The invention provides monodisperse polymer particles and dispersions thereof, said particles having a diameter of preferably 5 .mu.m or more. Such polymer dispersions are prepared by in a first step preparing a dispersion of smaller monodisperse polymer particles containing one or more materials having a very low solubility in water, and a relatively low molecular weight, then in a second step adding a partly water-soluble monomer which diffuses into the particles from the first step, and then effecting polymerization.

Abstract: This invention discloses a process for the nonaqueous dispersion polymerization of butadiene monomer in a reaction mixture containing a liquid nonaqueous dispersion medium, the improvement which comprises carrying out the polymerization of the butadiene monomer in the presence of at least one member selected from the group consisting of cis-1,4-poly(1,3-pentadiene), trans-1,4-poly(1,3-pentadiene), trans-1,2-poly(1,3-pentadiene), moderately high trans-1,4-polyisoprene, poly(2,3-dimethyl-1,3-butadiene), syndiotactic 1,2-polybutadiene, atactic 1,2-polybutadiene, butadiene/isoprene copolymers, butadiene/dimethylbutadiene/pentadiene terpolymers, styrene/1,3-pentadiene copolymers, mixtures of from 20% to 65% 3,4-polyisoprene and from 35% to 80% 1,4-polyisoprene, EPDM rubbers, and butyl rubbers to produce very high cis-1,4-polybutadiene.

Abstract: This invention relates to a method for reducing the amount of wall fouling in the suspension polymerization of vinyl chloride. The surfaces of the polymerization reactor are wetted with a solution containing from 5 to 50 wt % alkali metal hydroxide, 0.01 to 1 wt % free radical inhibitor and 0.01 to 1 wt % surface active agent prior to charging the vinyl chloride polymerization recipe to the reactor. Preferably, the surface of the wetted reactor is heated to a temperature from 40.degree. to 100.degree. C. for at least 5 minutes prior to charging the polymerization recipe.

Abstract: A hydrophobic liquid including a polyvalent isocyanate therein is dispersed in an aqueous medium in the presence of a specific polymer dissolved therein to form an emulsion system for producing microcapsules. The specific polymer dissolved in the aqueous medium is a homopolymer or copolymer including monomer units represented by the general formula: ##STR1## wherein R is hydrogen or alkyl, M is ammonium, sodium, potassium, lithium or hydrogen and Q is further represented by ##STR2## wherein Y is methylene, ethylene or polymethylene having 3 to 10 carbon atoms, which methylene, ethylene or polymethylene may be substituted by at least one alkyl.

Abstract: Process for the preparation of latices of vinyl acetate/olefin copolymers. Vinyl acetate is copolymerized with at least one olefin and, if desired, at least one other copolymerizable monomer, in aqueous emulsion, in the presence of an initiator, an emulsifier and a protective colloid comprising a water-soluble polymer (a) containing at least one monomer of acrylamide, methacrylamide or substituted or unsubstituted N-alkyl derivatives of acrylamide or methacrylamide and a water-soluble polymer (b) of ethylene glycol having a molecular weight between 1,000 and 50,000. The latices may be applied as binders in the manufacture of paints, glues, paper, textiles, floor coverings and mortar additives.

Abstract: This invention discloses a process for the nonaqueous dispersion polymerization of butadiene monomer in a reaction mixture containing a liquid nonaqueous dispersion medium, the improvement which comprises carrying out the polymerization of the butadiene monomer in the presence of at least one carbonylated polymer.

Abstract: A process for the manufacture of crosslinked ion exchange copolymer particles wherein small seed particles are swollen to final size by concurrently feeding monomer and polymerizing the same under controlled suspension conditions and the unique ion exchange particles produced thereby.

Abstract: This invention reveals a process for the nonaqueous dispersion polymerization of butadiene monomer in a reaction mixture containing a liquid nonaqueous dispersion medium, the improvement which comprises carrying out the polymerization of the butadiene monomer in the presence of high cis-1,4-polyisoprene to produce very high cis-1,4-polybutadiene.

Abstract: A block copolymer dispersion stabilizer for use in the aqueous dispersion polymerization of an ethylenically unsaturated monomer comprises at least two blocks linked by chemical valences. At least one of the blocks is hydrophilic (water soluble) and at least another of said blocks is hydrophobic (water insoluble). The hydrophobic block can contain a plurality of similar or dissimilar pendent groups having chemically reactive functionality. Examples of such groups are epoxy groups and ethylenically unsaturated bonds.

Abstract: In a process for preparing a vinyl chloride resin by polymerizing vinyl chloride alone or with up to 20% by weight of other polymerizable unsaturated monomers, in an aqueous suspension, in the presence of a monomer-soluble free radical catalyst and a suspension stabilizer which is partially hydrolyzed polyvinyl acetate or cellulose ether, there is an improvement wherein the polymerization is conducted in the presence of 0.02-0.3% by weight, based on the amount of monomer to be polymerized, of a cosuspension stabilizer which is a copolymer of 2-n-propyl-.DELTA..sup.2 -oxazoline, 2-isopropyl-.DELTA..sup.2 -oxazoline or both and 2-methyl-.DELTA..sup.2 oxazoline, 2-ethyl-.DELTA..sup.2 -oxazoline or both, the copolymer having a viscosity number of 35-70 (ml/g), measured at 25.degree. C. in an isopropanol/water mixture (50 vol-% of isopropanol), in a concentration of 0.5% (weight/volume of the solution).

Abstract: An acrylic resin emulsion which comprises an aqueous medium and particles of an acrylic resin emulsified and dispersed therein by the use of the emulsifier comprising as an essential component a polyester comprising in the molecule an amino-sulfonic acid type amphoionic group of the formula: ##STR1## wherein A is a straight or branched C.sub.1 -C.sub.6 alkylene group, a phenylene group or a substituted phenylene group.

Abstract: There is provided a method for the suspension polymerization of one or more styrenic monomers. This method involves increasing the amount of substantially water insoluble free radical initiator in the suspension after the conversion of the monomer has reached at least 50%. The temperature of the suspension is at least 110.degree. C. throughout the entire polymerization.

Abstract: The invention is to provide the methods for producing highly water-absorbable and water-retainable hydrogels having a large particle diameter together with a sufficient gel strength. The method is characterized by use of a specific dispersing agent in the water-in-oil type inverse phase suspension polymerization of an .alpha.,.beta.-unsaturated carboxylic acid and/or its alkali metal salt. Due to the high water-absorbability and water-retainability, along with the superior gel strength and the stable gel structure, the hydrogels of the invention enlarge the conventional range of usages.