Abstract: A method for producing a vinyl resin comprising the steps of dissolving or dispersing a polymerizable vinyl monomer in a polymerization solvent containing a silicone oil, and polymerizing the polymerizable vinyl monomer in the presence of a polymerization catalyst.

Abstract: Mono- or copolymers of water-soluble monomers of formula I are produced by preparing a two-phase system containing droplets of an aqueous solution of the monomers in a water-immiscible inert organic liquid. The monomers are polymerized in the presence of a combination of a suspending agent and an emulsifier.

Abstract: A crosslinked polymer composition obtained by the metathesis polymerization of a dicyclopentadiene monomer in which a chlorinated polymer such as a chlorinated elastomer or chlorinated polypropylene is dissolved; a crosslinked dicyclopentadiene polymer composition comprising a ring-opened dicyclopentadiene polymer and a dicyclopentadiene-soluble chlorinated polymer; and a method for preparing a crosslinked polymer composition comprising adding the chlorinated polymer to one of two reactant liquid streams, one of which contains dicyclopentadiene and a ring-opening metathesis catalyst and the other contains a catalyst activator, combining the two streams, and charging them to a mold or similar forming container in which the dicyclopentadiene polymerizes.

Abstract: A process for the preparation of toner particles which comprises mixing at least one resin monomer with a polymerization initiator, a crosslinking component and a chain transfer component; effecting bulk polymerization until partial polymerization has been accomplished; mixing with the aforementioned partially polymerized product pigment or dye particles, thereby forming an organic phase; dispersing the organic phase in water containing a stabilizing component whereby there is obtained a suspension of toner particles in water; and polymerizing the toner suspension.

Abstract: A process is described for carrying out aqueous and non-aqueous polymerization of polymerizable monomers, particularly vinyl monomers, and, preferably, vinylpyrrolidone, in the presence of a mixture of a stable, high purity, free-flowing, fine white powder of a substantially anhydrous 1:1 molar ratio complex of polyvinylpyrrolidone-hydrogen peroxide (PVP--H.sub.2 O.sub.2), respectively, and a transition metallic ion, as a free radical initiator, is described herein. Preferred polymerizations are the homopolymerization of vinylpyrrolidone and the copolymerization of maleic anhydride and a C.sub.1 -C.sub.5 alkyl vinyl ether.

Abstract: A process for preparing a particulate vinyl polymer resin and vinyl polymer resin derived therefrom wherein, comprising polymerization in the presence of a dispersant or graft dispersant having no ionic side groups, optionally containing terminal functional groups, said dispersant is derived from repeating units of .alpha.,.beta.-unsaturated ester(s) of acrylic and/or methacrylic acid and having a molecular weight average of from about 500 to about 50,000.

Abstract: A process of producing a vinyl chloride polymer, comprising the step of suspension polymerizing vinyl chloride or a monomer mixture comprising mainly vinyl chloride in the presence of an oil-soluble polymerization initiator in an aqueous medium containing a dispersant, wherein said dispersant comprises:(A) a partially saponified polyvinyl alcohol,(B) a hydroxypropylmethyl cellulose, and(C) a crosslinked polymer having a carboxyl group.This process can produce a vinyl chloride polymer having a high bulk density and a high porosity and therefore capable of producing an extruded product with an extremely small amount of fish eyes, at high efficiency and high productivity.

Abstract: Uniformly sized polymer particles of 1-50 .mu.m diameter are made by gradually combining a water-insoluble monomer mixture with an aqueous dispersion of emulsion-polymerized polymer particles in the presence of a dispersion stabilizer and an oil-soluble, free-radical polymerization initiator.

Abstract: This invention relates to a process for the radical homo-or copolymerization of acrylonitrile with one or more copolymerizable monomers under reaction conditions such that the monomers are present predominantly in a gaseous form of an adsorbed form and polymerization of the monomers, which are presumably adsorbed, takes place in the solid phase (solvent-free polymerization) and results in pulverulent PAN-(co)polymers. The process is preferably carried out in the presence of small quantities of a mediator substance such as dimethylformamide which does not alter the pulverulent consistency of the PAN-polymers but leads considerably more rapidly and with much improved yields to freshly formed polyacrylonitrile polymers.

Abstract: A process for producing a vinyl chloride polymer for matted moldings which comprises performing the suspension polymerization of vinyl chloride monomer or a mixture of vinyl monomers composed mainly of vinyl chloride in an aqueous medium, said suspension polymerization being performed after the addition of an aqueous dispersion obtained by dispersing a polyfunctional monomer having 2 or more ethylenic double bonds in the molecule into an aqueous solution of a water-soluble partially saponified polyvinyl alcohol, a water-soluble cellulose eter or an emulsifier, thereby yielding a vinyl chloride resin composed of 5 to 90 wt % tetrahydrofuran-insoluble gel fraction, with the remainder being tetrahydrofuran-solubles.

Abstract: Monodisperse latexes of at least 2-30 microns particle size are prepared from an emulsion recipe comprising a monodisperse seed latex polymer on the order of 2 microns or less particle size, a polymerizable monomer, an initiator, at least one inhibitor, and a water-soluble polymeric emulsifier of 10.sup.4 -10.sup.7 molecular weight. Optional ingredients are crosslinking monomer, oil-soluble inhibitor if the mixture is to be stored before polymerization, and one or more additional emulsifiers selected from a water-soluble comonomer or polymer of 0.3.times.10.sup.3 -5.times.10.sup.3 molecular weight and a non-polymeric anionic emulsifier. Additional particle size growth and monodisperse latex yield are realized by polymerization in a microgravity environment.

Abstract: A family of ionic polyacetylenes containing long sequences of conjugated double bonds in the backbone with ionic charges adjacent to or in conjugation with the backbone, and a synthetic process for preparing them, are disclosed. These polymers, which are soluble in many solvents including water, are mono- and di-substituted polyacetylenes that are extensively conjugated. The charge density and geometry of charge distribution depends on the number and nature of the substituents.

Abstract: A process for producing styrene-containing polymers having a narrow particle size distribution, comprising the steps:(i) preparing a polymerization mixture, said mixture comprisinga) an organic phase comprising at least 50 wt %. styrene and a monomer-soluble polymerization initiator, andb) an aqueous phase comprising water, an organic protective colloid and a substantially water insoluble inorganic suspension stabilizer;(ii) adding to said polymerization mixture 50-500 ppm of a metal carbonate, bicarbonate or mixtures thereof based on said aqueous phase; and(iii) polymerizing said polymer mixture to produce said styrene-containing polymer particles.

Abstract: A method of producing polymer particles having a particle size distribution of .+-.25% with respect to each average particle size in an amount of 95 wt. % or more, within the average particle sizes ranging from 1 .mu.m to 100 .mu.m, is disclosed, which comprises the steps of: (1) adding a polymer dispersion stabilizer in an amount of 0.1 to 10 wt. % to a hydrophilic organic liquid in which the polymer dispersion stabilizer is soluble; (2) adding thereto at least one vinyl monomer in an amount of not more than 50 times by weight the amount of the polymeric dispersion stabilizer, which monomer is soluble in the hydrophilic organic liquid, but a polymer synthesized from the monomer being swelled or substantially insoluble in the hydrophilic organic liquid; and (3) polymerizing the monomer under the condition that the amount of the vinyl monomer is 200 wt. % or less of the hydrophilic organic liquid.

Abstract: Vinyl polymers, e.g., the homo- and copolyvinyl chlorides, are prepared in one or more stages, to a degree of conversion of at least 50%, by suspended emulsion polymerizing at least one vinyl monomer, e.g., vinyl chloride, said at least one monomer having dispersed therein finely divided droplets of an aqueous solution of at least one component of a polymerization initiating system, and wherein the amount of water in said aqueous solution constitutes at least 19%, and preferably at least 20% by weight of the at least one monomer.

Abstract: A process for the preparation of polymeric particles which comprises mixing at least one monomer with a polymerization initiator, a crosslinking component and a chain transfer component; effecting bulk polymerization until partial polymerization results; dispersing the aforementioned partially polymerized monomer product in water containing a stabilizing component to obtain a suspension of particles in water and polymerizing the resulting suspension.

Abstract: Hydroxylated acrylic copolymers in solid form which are the product of the suspension polymerization containing from 1 to 8 carbon atoms in the alcohol chain, hydroxyalkylacrylates or methacrylates, and acrylic or methacrylic acid and contain from 0.5 to 8% free hydroxyl groups and from 0.1 to 5% free carboxyl groups which are capable of reacting with compounds containing reactive groups such as isocyanates or their prepolymers, amines containing--NH--CH.sub.2 OH-- groups or epoxy groups provide improved binders for paints and shellacs used for plastics.

Abstract: Copolymers of .alpha.-methylstyrene and acrylonitrile having improved composition of uniformity are prepared by emulsion polymerizing a first monomer stream having a weight ratio of .alpha.-methylstyrene/acrylonitrile from about 75/25 to about 85/15 and thereafter polymerizing a second monomer feed stream comprising acrylonitrile.

Abstract: A process for emulsion-polymerizing unsaturated monomer(s) is disclosed. When a hydrazine derivative having at least two hydrazine residues per molecule is added to the polymer dispersion obtained by said emulsion polymerization process, a polymer dispersion composition capable of forming a film which is excellent in blocking resistance, adhesiveness to an alkyd resin film, water-resistant adhesiveness to an alkyd resin film and water-resistant anti-whitening can be obtained.

Abstract: Highly crosslinked polymer particles, which may be porous, consisting essentially of a non-hydrophilic polymer can be produced by adding a polymerizable monomer mixture comprising at least 20% by weight of at least one non-hydrophilic, crosslinking polyvinyl monomer to an aqueous dispersion containing a non-crosslinked, low molecular weight polymer particles having a weight average molecular weight of 500-10,000 as a dispersoid, with a non-reactive solvent in a proportion of not more than 1 part by weight per part by weight of the polymerizable monomer mixture, the proportion of the polymerizable monomer mixture plus the non-reactive solvent to the non-crosslinked, low molecular weight polymer particles being 4 to 20 parts by weight per part by weight of the non-crosslinked, low molecular weight polymer particles, and then subjecting the polymerizable monomer mixture to radical emulsion polymerization with stirring.

Abstract: The viscosity of the dispersing medium, such as cyclohexane, in the anionic dispersion polymerization of monomers, such as styrene, is increased by adding a higher viscosity inert miscible liquid, such as hexadecane, or a soluble inert solid, or by using a liquid having a viscosity of greater than about 2 cp. The increased viscosity assists in the formation of dispersed polymer particles having a narrower particle size distribution than those produced in the lower viscosity dispersing medium.

Abstract: A radiation curable liquid resin composition comprising a radiation curable liquid base resin and polymer microparticles having an average particle size from 0.01 to 0.6 microns. The incorporation of polymer microparticles to the base resin may improve the rheological property of the liquid composition and also the physical properties of cured film therefrom.

Abstract: Polymers obtainable by subjecting at least one monomer, polymerizable by free radicals, to a free-radical emulsion polymerization in the presence of a polymer of the formulae I and/or II ##STR1## in which M, n, R, R.sup.1, R.sup.2, x and y have the meanings mentioned in the description, the use of the polymers obtained for surface-sizing of paper or paper-like materials and also novel polymers of the formulae I and/or II.

Abstract: A graft copolymer having dispersion stabilizing effect, which is a product of the polymerization of 5 to 30% by weight of a macromonomer which has a molecular weight of 1,000 to 100,000 and has a radical polymerizable unsaturated group at its one end, 1 to 40% by weight of a hydrophillic monomer which has a hydrophillic moiety in it and has a radical polymerizable unsaturated group, and 5 to 40% by weight of a fluorinated monomer which has a florinated moiety in it and has a radical polymerizable unsaturated group, the % by weight being based on a total of the three monomers, and 0 to 50% of the total of the total of the three monomers of a monomer copolymerizable therewith.

Abstract: Disclosed is a method for preparing poly(2-hydroxyethyl methacrylate) polymers (PHEMA) by a precipitation/suspension polymerization technique wherein a reaction mixture comprising hydroxyethyl methacrylate monomer (HEMA), solvent, and a free-radical initiator is subjected to heating for a time adequate for said PHEMA to be formed. The improvement in process of the present invention comprises restricting said HEMA to contain less than about 0.5 wt-% polyfunctional acrylate content, incorporating a suspending agent in said reaction mixture, agitating said reaction mixture during said heating, and restricting said solvent to one having a solubility parameter of between about 7.5 and 9, to produce PHEMA polymer particles ranging in size from about 30 to 1,000 microns and having a molecular weight ranging from about 500,000 to 2,000,000.

Abstract: A novel cementing composition comprising a hydraulic cement and, as a fluid loss agent, water-soluble, nonionic hydrophobically modified hydroxyethyl cellulose, are disclosed. Preferably, the cementing composition further comprises water-soluble, nonionic hydroxyethyl cellulose as a second fluid loss agent. A novel aqueous slurry containing the cementing composition, a novel process of using the aqueous slurry to fill an annulus between a borehole wall and casing, and a novel composition of matter comprising specified amounts of water-soluble, nonionic hydrophobically modified hydroxyethyl cellulose and water-soluble, nonionic hydroxyethyl cellulose, are also disclosed.

Abstract: A method of producing polymer particles having a particle size distribution of .+-.25% with respect to each average particle size in an amount of 95 wt. % or more, within the average particle sizes ranging from 1 .mu.m to 100 .mu.m, is disclosed, which comprises the steps of: (1) adding a polymer dispersion stabilizer in an amount of 0.1 to 10 wt. % to a hydrophilic organic liquid in which the polymeric dispersion stabilizer is soluble; (2) adding thereto at least one vinyl monomer in an amount of not more than 50 times by weight the amount of the polymeric dispersion stabilizer, which monomer is soluble in the hydrophilic organic liquid, but a polymer synthesized from the monomer being swelled or substantially insoluble in the hydrophilic organic liquid; and (3) polymerizing the monomer under the condition that the amount of the vinyl monomer is 200 wt. % or less of the hydrophilic organic liquid.

Abstract: Polymers in bead form are prepared from water-soluble ethylenically unsaturated monomers by a reverse suspension polymerization of a liquid in the presence of polymerization initiators and protective colloids obtainable by grafting polymers (A) containing (a) aromatic monovinyl monome from 40 to 100% by weight (b) C.sub.3-6 monoethylenically unsaturated carboxylic acid and/or maleic anhydride from 0 to 60% by weight (c) other monoethylenically unsaturated monomers from 0-20% by weight, as copolymerized units with the proviso that the sum of the weight (a) to (c) is always 100 and the polymer (A) has a molecular weight (number average) from 500 to 20,000 and a hydrogenation iodine number from 1.3 to 51 with a fixed monomer mixture at given concentration levels.

Abstract: A novel process for the preparation of a readily dispersible, pourable dispersion powder comprising emulsion polymerizing in the presence of a free radial initiator a mixture of 1 to 50% by weight of ethylene and 99 to 50% by weight of an ethylenically unsaturated comonomer phase comprising at least one member of the group consisting of (a) 60 to 100% by weight of vinyl chloride, (b) 0 to 40% by weight of monoethylically unsaturated, oil-soluble monomers, (c) 0 to 10% by weight of monoethylenically unsaturated water-soluble monomers having functional groups and (d) 0 to 5% by weight of oil-soluble monomers that are monoethylenically unsaturated and have functional groups or are multiple ethylenically unsaturated and optionally a protective colloid and/or emulsifier at an ethylene pressure of 10 to 150 bar to obtain an aqueous dispersion of a vinyl chloride-ethyelene copolymer, optionally adding to the aqueous dispersion (e) 0 to 40% by weight, based on the VCE-polymer, of at least one water-soluble substance

Abstract: A method for preparing pulverulent olefin-maleic anhydride copolymers from concentrated solutions of olefins and maleic anhydride in organic solvents, by radical polymerization in the presence of dispersants.

Abstract: A process for the preparation of finely-divided aqueous copolymer dispersions with a solids content of 10 to 70% by weight, based on the dispersion, comprising emulsion polymerizing (a) 1 to 50% by weight of ethylene and (b) 99 to 50% by weight of at least two ethylenically unsaturated comonomers in the presence of a free-radial initiator and at least one member of the group consisting of emulsifier and a protective colloid and optionally present conventional adjuvants, the ethylenically unsaturataed comonomers being (b1) 79.5 to 99.5% by weight of vinyl chloride, (b2) 0 to 15% by weight of ethylenically unsaturated oil-soluble monomers, (b3) 0.

Abstract: Nonaqueous polymer dispersions are obtainable by polymerization of esters (A) of acrylic acid and/or methacrylic acid and/or ethylacrylic acid with C.sub.1 -C.sub.20 -alcohols in an organic solvent or a mixture of organic solvents in which the polymers formed are insoluble, and in the presence of copolymers (B) having a molecular weight of from 500 to 20,000 and obtainable by bulk or solution polymerization of monoolefinically unsaturated monomers at from 180.degree. to 400.degree. C. and from 1 to 200 bar, and the said dispersions are used for the production of finishes, coating materials and adhesives.

Abstract: Disclosed is an improved method for making a thermoset polymer wherein a plurality of reactant streams, one of which contains the activator of a metathesis catalyst system combined with a moderator, and a second of which contains the catalyst of the metathesis catalyst system and at least one of which contains dicyclopentadiene are combined to form a reaction mixture, and the reaction mixture is then injected into a mold where polymerization occurs. The improvement comprises adding to the reaction mixture 1-25 mols of a cationic polymerization initiator per 1000 mols of dicyclopentadiene.

Abstract: Styrene or other anionically polymerizable monomer is anionically homopolymerized in a dispersion using a non-solvent, e.g., hexane using three or more stages to obtain spherical microparticles, e.g., 2-5 microns, with a narrow size distribution.

Abstract: Disclosed are aqueous polyacrylate dispersions, i.e., aqueous latex dispersions of acrylate polymers, having improved rheological and stability characteristics, prepared by polymerization of acrylic esters, methacrylic esters and mixtures thereof in the presence of, by weight of the total monomer content, (a) from about 0.05 to about 5% of at least one non-surface active protective colloid, (b) from about 0.01 to 1% of at least one or more initiators selected from the group consisting of azo based initiators and organo-soluble, water-insoluble peroxide initiators, and (c) greater than 0.01% to about 0.05% of a water-soluble peroxide initiator. The resultant aqueous polyacrylate dispersions are useful in the manufacture of latex paints, binders for nonwoven materials, water-based inks, paper coatings and water-borne adhesives, such as pressure-sensitive adhesives.

Abstract: A copolymer of an olefin and maleic anhydride is produced in the form of particles by co-polymerizing an olefin having 2 to 8 carbon atoms with maleic anhydride in a solvent capable of dissolving both co-monomers, but incapable of dissolving the copolymer in the presence of a dispersant of an oil-soluble, cationic copolymer comprising (a) ethylenically unsaturated monomer units having cationic groups of a quaternary ammonium salt and (b) lipophilic, ethylenically unsaturated monomer units.

Abstract: Monodisperse latexes of at least 2-30 microns particle size are prepared from an emulsion recipe comprising a monodisperse seed latex polymer on the order of 2 microns or less particle size, a polymerizable monomer, an initiator, at least one inhibitor, and a water-soluble polymeric emulsifer of 10.sup.4 -10.sup.7 molecular weight. Optional ingredients are cross-linking monomer, oil-soluble inhibitor if the mixture is to be stored before polymerization, and one or more additional emulsifiers selected from a water-soluble comonomer or polymer of 0.3.times.10.sup.3 -5.times.10.sup.3 molecular weight and a non-polymeric anionic emulsifier. Additional particle size growth and monodisperse latex yield are realized by polymerization in a microgravity environment.

Abstract: A toner suitable for developing electrostatic images is produced through a process comprising: dispersing a monomer composition comprising at least a polymerizable monomer and a colorant in an aqueous medium heated at a temperature higher than a polymerization temperature, thereby to form particles of the monomer composition; adjusting the aqueous medium to the polymerization temperature; and adding a substantially water-insoluble polymerization initiator to the aqueous medium containing the particles of the monomer composition dispersed therein and adjusted to the polymerization temperature, thereby to cause the polymerization of the polymerizable monomer. According to this process, a toner containing a large amount of a low-softening point compound and having good fixability at low pressure and/or low temperature can be produced while retaining good anti-blocking characteristic and fluidity.

Abstract: A method of manufacturing pulverulent polymaleic anhydrides in which maleic anhydride is polymerized in an organic solvent in the presence of a dispersant. Polymerization results in high yields of polymaleic anhydride, as a colorless or faintly colored powder.

Abstract: A terpolymer of acrylic acid, ethyl acrylate and N-tert-butylacrylamide is prepared by suspension polymerization.

Abstract: A high solids latex of a functional monomer may be prepared by emulsion polymerization of the monomer charge to a specified overall conversion and then introducing an additional micelle forming surfactant or a unimodal seed latex and continuing the polymerization.

Abstract: Use of, and composition containing the reaction products of primary 2-alkyl-1-alkanols containing from 12 to 36 carbon atoms with ethylene oxide and/or propylene oxide as emulsifiers or co-emulsifiers in the emulsion polymerization of ethylenically unsaturated monomers.

Abstract: Disclosed is a method of producing coagulated colloidal particles with close-packed structure which comprises;(A) adding a coagulant to aqueous colloidal particles at a temperature lower than softening temperature of the colloidal particles under such conditions that said coagulant will be present in discrete units in the dispersion before it is brought into solution by diffusion;(B) allowing the molecules of coagulant to gradually diffuse from said coagulant units into the surrounding dispersion, thereby coagulating the colloidal particles on the surface of each coagulant unit, causing the coagulated particles to grow from inside to outside of each unit, and producing coagulated particles of desired size with regularly packed structure;(C) separating the coagulated particles thus formed from the dispersion; and(D) drying, or heating in an aqueous phase, the coagulated particles separated above at a temperature lower than the softening point of said colloidal particles.

Abstract: A process for production of a vinyl polymer by suspension polymerization or emulsion polymerization of at least one kind of vinyl monomer in an aqueous medium is disclosed.In this process, the polymerization is carried out in a polymerizer, the inner wall surface and portions of the auxiliary equipment thereof which may come into contact with the monomer during polymerization having a surface roughness of not greater than 5 .mu.m and being previously coated with a scaling preventive comprising at least one selected from dyes, pigments and aromatic or heterocyclic compounds having at least 5 conjugated .pi. bonds. According to this process, scaling on the inner wall surface of a polymerizer, etc. during polymerization can be prevented effectively and surely.

Abstract: This process is a process for production of a vinyl chloride polymer by suspension polymerization or emulsion polymerization of vinyl chloride monomer or a mixture of vinyl chloride monomer with a vinyl monomer copolymerizable with said vinyl chloride monomer in an aqueous medium, characterized in that the polymerization is carried out in a polymerizer, the inner wall surface and portions of the auxiliary equipment thereof which may come into contact with the monomer during polymerization being previously coated with a scaling preventive comprising at least one selected from dyes, pigments and aromatic or heterocyclic compounds having at least 5 conjugated .pi. bonds, while controlling the chloride ion concentration in the reaction mixture to not higher than 100 ppm. According to said process, scaling onto the inner wall surface of a polymerizer, etc. during polymerization can be prevented effectively and surely.

Abstract: Porous particles of vinyl resin are disclosed where said particles are non-spherical in shape, highly porous, skinless and friable. Processes are also disclosed for producing these novel particles. The particles are preferably PVC and exhibit an ability to absorb large amounts of plasticizer in a short time.

Abstract: A process for the gas phase homopolymerization of vinyl chloride or the gas phase copolymerization of vinyl chloride with a monomer copolymerizable therewith, wherein when the breeding ratio first exceeds 3.5 after initiation of the polymerization, the feed rate of a seed polymer is adjusted so that the breeding ratio is maintained at a level of from 3.5 to 5.5.

Abstract: There is disclosed a suspension polymerization of vinyl chloride in which the suspension of monomers as droplets is maintained, and the droplets of polymer are prevented from coalescence by the addition of an expanding lattice clay, preferably a magnesium alumina silicate clay, most preferably, Veegum, and a hydrophilic polymer. The hydrophilic polymer can be a partially hydrolized polyvinyl alcohol, a hydroxyalkyl cellulose ether, or a cross-linked polyacrylic acid, the latter being preferred. These addities enhance polymerization by reducing polymerization time and reducing deposition of the polymer in the reactor. Additionally, the shape and particle size distribution of the polymer is improved.

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 group 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.