Abstract: Process for the preparation of thermoplastic copolymers of .alpha.-methylstyrene and acrylonitrile by continuous bulk copolymerization ofA. 30 to 50 mol % of .alpha.-methylstyrene andB. 70 to 50 mol % of acrylonitrileat temperatures from 60.degree. to 120.degree. C. with average residence times of 4 to 12 hours in the presence of initiators which supply free radicals, carried out in at least two continuously operated mixed tank reactors, characterized in that 100 molar parts of a monomer mixture ofA.sub.0. 34 to 52 mol % of .alpha.-methylstyrene andB.sub.0. 66 to 48 mol % of acrylonitrileare fed continuously into the first tank reactor per unit time, and, with back-mixing, are copolymerized up to a conversion of 5 to 30 molar parts to give a copolymer of the compositionA.sub.1. 49 to 53 mol % of .alpha.-methylstyrene andB.sub.1. 51 to 47 mol % of acrylonitrile,and the mixture consisting of 70 to 95 molar parts of the monomers A and B and 5 to 30 molar parts of the copolymer of the composition A.sub.1 -B.sub.

Abstract: A polymerization process which comprises contacting at least one polar acrylic type or maleimide monomer under polymerization conditions with (i) a tetracoordinate organosilicon, organotin or organogermanium initiator having at least one initiating site, (ii) a co-catalyst which is a source of fluoride, bifluoride, cyanide or azide ions or a Lewis acid, and (iii) from 0.1 to 10% by weight, based on the weight of monomer, of acetonitrile.

Abstract: Copolymers of acrylonitrile with aliphatic cross-linkers having two or more unconjugated vinylic groups are functionalized with polyamines to form weakly basic anion exchange resins having both low rinse-volume requirements and high anion exchange capacity.

Abstract: Hydrophilic polymers of the type suitable for use in making contact lenses and having a wide range of controllable properties including strength and gas permeability are formed from acrylonitrile or methyl methacrylate or an analogue thereof, 1-vinyl-2-pyrrolidinone and an appropriate amount of a cross-linking agent. Contact lenses (3) having an interferometric pattern thereon are also disclosed.

Abstract: Copolymers of from 65 to 75%, by weight, of .alpha.-methyl styrene and from 35 to 25%, by weight, of .alpha.-methyl styrene and from 35 to 25%, by weight, of acrylonitrile, obtainable by radical emulsion polymerization, the monomers being metered in during the course of the polymerization, wherein the molar ratio: ##EQU1## of the unreacted monomers in the reaction mixture is maintained during the metering phase between 0.7 and 1.25.

Abstract: Sulphur-containing polymers of styrene, .alpha.-methyl styrene, p-methyl styrene, vinyl toluene, acrylonitrile or methyl methacrylate or mixtures thereof with a limiting viscosity of from 2 to 15 ml/g (measured in dimethyl formamide at 25.degree. C.) and a sulphur content of from 1.15 to 3.95% by weight, whereby at least 90% by weight of the incorporated sulphur is present as a constituent of terminal C.sub.1-18 -thioalkyl groups.

Abstract: Monofils and bristles which comprise at least 90% by weight of acrylonitrile units and have a linear density of more than 2.5 tex possess a relative solution viscosity of 1.7 to 6.0, a tear strength of at least 20 cN/tex and an initial modulus of more than 700 cN/tex.The manufacturing process is distinguished by a wet stretch of the spun filaments by at least 1:4, drying under tension and a subsequent hot stretch of at least 1:2, the overall stretch being at least 1:8, preferably 1:10 to 1:20.The monofils and bristles according to the invention are suitable in particular for producing filament-reinforced composite materials.

Abstract: A method for producing by suspension polymerization a copolymer comprising a vinyl cyanide compound and an aromatic vinyl compound having excellent transparency, and uniform composition, and a content of the polymerized residue of vinyl cyanide compound in the range of from 50 to 85% by weight comprising the steps of: (a) carrying out initial charging of the total quantity of the vinyl cyanide compound and a partial quantity of the aromatic vinyl compound at a compositional ratio, wherein the content of the vinyl cyanide compound in the resulting copolymer attains an intended ratio within a range of from 50 to 85% by weight; (b) initiating the copolymerization reaction by adding a polymerization initiator having a decomposition half-life at 95.degree. C.

Abstract: A process for producing acrylonitrile-based copolymers for carbon fibers is described, which comprises producing substantially metal-free acrylonitrile-based copolymers containing as essential components at least 95% by weight of acrylonitrile and from 0.5 to 3% by weight of a carboxyl group-containing polymerizable unsaturated monomer, at least 20% of the carboxyl groups being substituted with ammonium ions, in the presence of a redox polymerization initiator comprising ammonium persulfate and ammonium sulfite and, thereafter, spinning the acrylonitrile-based copolymer. The present invention permits production of acrylonitrile-based copolymers free of metal impurities responsible for the formation of defects in the ultimate carbon fibers. High performance carbon fibers can be produced without the need of any additional steps.

Abstract: A process for preparing .alpha.-methylstyrene/acrylonitrile copolymers by suspension or bulk polymerization of .alpha.-methylstyrene and acrylonitrile with or without other vinyl compounds such as styrene, methyl methacrylate, vinyl toluene and t-butylstyrene in the presence of a difunctional organic peroxide, preferably a difunctional organic peroxide having a 10 hour half-life temperature of 60.degree. to 110.degree. C., at a polymerization temperature of 80.degree. to 120.degree. C. The process produces the copolymers having excellent transparency, heat resistance and strength in high conversions in a short time.

Abstract: Novel salts of alkenylsuccinic monoesters represented by the following formulas (I) or (II): ##STR1## in which R.sub.1 represents a hydrocarbon group, R.sub.2 represents a hydrogen atom or a methyl group, A represents an alkylene group having from 2 to 4 carbon atoms, B represents a carbonyl group or a methylene group, M is a monovalent or divalent cation.The monoesters can be emulsion-polymerized under optimum conditions while varying the hydrophilic and oleophilic balance depending on the type of monomer because they have hydrophobic hydrocarbon groups and oleophilic carboxylate groups and ether bonds of polyalkyleneoxy groups.The compounds according to the invention are an excellent reactive surface active agent, and also useful as an improver or modifier for polymer because they can impart hydrophilicity to hydrophobic resins when they are used in larger amounts as in the case of reactive surface active agents employed for ordinary.

Abstract: An improved process for preparing a sticky water-soluble polymer, e.g. acrylamide polymers and acrylic acid polymers, which comprises polymerizing an aqueous solution of a monomer in a polymerization vessel of which the surface contacting the aqueous monomer solution is covered with a tetrafluoroethylene-ethylene copolymer film, whereby the stickiness of the produced polymer to the vessel is remarkably decreased, namely the peelability of the polymer from the vessel is remarkably improved, and moreover the polymerization conversion is remarkably improved. Also, the use of a metal deposited tetrafluoroethylene-ethylene copolymer film as a covering material improves the efficiency of a photopolymerization and enables to use a polymerization vessel made of an inexpensive material.

Abstract: Polyamides can be formed in good yields by the copolymerization of at least one alpha, beta-unsaturated nitrile with at least one alpha, beta-unsaturated carboxylic acid or ammonium salt thereof. These polymers are suitable for use as fibers, plastics, films and molding resins.

Abstract: Copolymers of acrylonitrile and propylene are produced by the process of the instant invention. This process comprises polymerizing (1) a major portion of an olefinically unsaturated nitrile monomer with (2) a minor portion of propylene, in the presence of a free radical initiator, while maintaining the molar ratio of propylene to the olefinically unsaturated nitrile during polymerization at a ratio greater than the molar ratio of propylene to the olefinically unsaturated nitrile in the final polymer.

Abstract: A process for preparing .alpha.-methylstyrene/acrylonitrile copolymer by suspension or bulk polymerization of .alpha.-methylstyrene and acrylonitrile with at least one member selected from the group consisting of styrene, chlorostyrene, para-methylstyrene, t-butylstyrene, acrylic ester and methacrylic ester in the presence of a difunctional organic peroxide having a 10 hour half-life temperature of 60.degree. to 120.degree. C. and capable of producing a t-butyl radical, at a polymerization temperature of 80.degree. to 135.degree. C. The process produces the copolymers having excellent transparency, heat resistance and strength in a high conversion in a short time.

Abstract: A process and apparatus for the continuous mass polymerization of styrenic and alkenylnitrile monomers.

Abstract: A process and apparatus for the continuous mass polymerization of styrenic and alkenylnitrile monomers. The process comprises the steps of continuously introducing a feed comprising a predetermined ratio of styrenic and alkenylnitrile monomers into a reaction vessel to produce a reaction mixture; subjecting the reaction mixture to conditions of temperature and pressure under which said monomers copolymerize to produce a styrenic/alkenylnitrile copolymer; subjecting the reaction mixture to sufficient agitation; continuously withdrawing styrenic/alkenylnitrile copolymer from the reaction vessel; and devolatilizing the styrenic/alkenylnitrile withdrawn from the reaction vessel by a two-stage procedure including first adjusting the ratio of styrenic to alkenylnitrile monomer therein followed by heating to volatilize the volatile components and then separation of volatile components.

Abstract: Disclosed is a process and apparatus for the continuous mass polymerization of styrenic and alkenylnitrile monomers. The process comprises the steps of continuously introducing a feed comprising a predetermined ratio of styrenic and alkenylnitrile monomers into a reaction vessel to produce a reaction mixture; subjecting the reaction mixture to conditions of temperature and pressure under which said monomers copolymerize to produce a styrenic/alkenylnitrile copolymer; subjecting the reaction mixture to agitation; continuously withdrawing styrenic/alkenylnitrile copolymer from the reaction vessel; and by withdrawing vapor phase from the reaction vessel in a controlled amount by varying the amount of cooled surface available for condensing the vapors, condensing the vapors by contact with the cooled surface and returning the condensate to the reaction vessel. The process and apparatus also include a novel means for devolatilizing the product copolymer.

Abstract: Disclosed is a process for the continuous mass polymerization of styrenic and alkenylnitrile monomers. The process comprises the steps of continuously introducing a feed comprising a predetermined ratio of styrenic and alkenylnitrile monomers into a reaction vessel to produce a reaction mixture; subjecting the reaction mixture to conditions of temperature and pressure under which said monomers copolymerize to produce a styrenic/alkenylnitrile copolymer; subjecting the reaction mixture to sufficient agitation; continuously withdrawing styrenic/alkenylnitrile copolymer from the reaction vessel; and devolatilizing the styrenic/alkenylnitrile withdrawn from the reaction vessel by a two-stage procedure including first adjusting the ratio of styrenic to alkenylnitrile monomer therein followed by heating to volatilize the volatile components and then separation of volatile components.

Abstract: A process and apparatus for the continuous mass polymerization of styrenic and alkenylnitrile monomers. The process comprises the steps of continuously introducing a feed comprising a predetermined ratio of styrenic and alkenylnitrile monomers into a reaction vessel to produce a reaction mixture; subjecting the reaction mixture to conditions of temperature and pressure under which said monomers copolymerize to produce a styrenic/alkenylnitrile copolymer; subjecting the reaction mixture to agitation; continuously withdrawing styrenic/alkenylnitrile copolymer from the reaction vessel; and by withdrawing vapor phase from the reaction vessel in a controlled amount by varying the amount of cooled surface available for condensing the vapors, condensing the vapors by contact with the cooled surface and returning the condensate to the reaction vessel. The process and apparatus also include a novel means for devolatilizing the product copolymer.

Abstract: A copolymer consisting of 30 to 65 mole % of structural units of the formula ##STR1## 1 to 55 mole % of structural units of the formula ##STR2## and 10 to 60 mole % of structural units of the formula ##STR3## and having a number average molecular weight of 500 to 200,000.

Abstract: Improved rate of dissolution in liquid hydrocarbon fuels, of specified tert-butylstyrene copolymers capable of imparting anti-misting characteristics to the fuel, is obtained when the copolymer, following its production by aqueous emulsion polymerization of the monomers, is isolated from the resulting latex by a process of flocculation, separation, washing and drying at moderate temperatures. The copolymer thus isolated is advantageously incorporated in the liquid fuel in the form of a slurry with a hydroxylic liquid and an amine.

Abstract: Disclosed is a process and apparatus for the continuous mass polymerization of styrenic and alkenylnitrile monomers.

Abstract: In the suspension polymerization of acrylonitrile in an aqueous medium, the polymerization is conducted in the presence of a water-soluble polymer and an oil soluble radical initiator while maintaining the acrylonitrile concentration higher than 9 weight percent in the polymerization system, whereby the polymerization of acrylonitrile in the water phase is suppressed and a high molecular weight polymer (weight average molecular weight not less than 400,000) having uniform particle diameters is produced.

Abstract: An improved process for the preparation of heat resistant copolymers of an alpha-methylstyrene and acrylonitrile by polymerization thereof in aqueous emulsion, and in the presence of a free-radical-supplying compound and a chain-transfer agent. The polymerization reaction is insufficiently cooled to remove all of the released reaction heat, and in combination therewith the polymerization is conducted at a temperature of the aqueous emulsion maintained at a level of at most 110.degree., while further maintaining the mean rate of temperature increase per hour, v, at a value of at most 60.degree. C. per hour, wherein v is determined by the formula: ##EQU1## in which: T.sub.m =maximum temperature of the aqueous emulsion (.degree.C.),T.sub.o =temperature of the aqueous emulsion at the start of the polymerization (.degree.C.)t.sub.m =time in hours at which T.sub.m is reached, andt.sub.o =time in hours at which the polymerization is started whereby the rate of monomer conversion is maximized.

Abstract: An .alpha.-methylstyrene high-content copolymer which is characterized by that it is a copolymer which comprises 65-90 parts by weight of .alpha.-methylstyrene with 35-10 parts by weight of acrylonitrile and 0-5 parts by weight of a copolymerizable vinyl monomer or monomers and that a component having an .alpha.-methylstyrene content of 82% or higher is contained in an amount of 30 parts by weight or more. Such a copolymer may be produced by a process which comprises charging 65 parts by weight or more of .alpha.-methylstyrene and 10% by weight or less based on this .alpha.-methylstyrene of acrylonitrile and a vinyl monomer or monomers all in one portion at the initial stage, making the system fully emulsified, gradually adding 35 parts by weight or less of acrylonitrile and the vinyl monomer or monomers, and carrying out emulsion polymerization until the amount of a polymer produced has amounted to 50 parts by weight or more in such way that the ratio of the .alpha.

Abstract: The di-ester of beta-pentabromophenoxyethanol and succinic acid, bis(beta-pentabromophenoxyethyl) succinate, is prepared by mono-ethoxylating pentabromophenol with ethylene oxide, then esterifying the resulting pentabromophenoxyethanol with succinic acid. The di-ester is a flame retardant for ABS.

Abstract: In the emulsion copolymerization of styrene and acrylonitrile, the copolymer yield can be increased by adding certain antioxidant compounds to the emulsifier. These antioxidant compounds include an aromatic portion and a fatty acid portion, and may be, for example, a hydroquinone-fatty acid ester.

Abstract: An acrylonitrile polymer comprising acrylonitrile, at least one of vinyl chloride and vinylidene chloride, a sulfo group-containing vinyl monomer having a higher reactivity ratio than acrylonitrile and a methallyl sulfonic acid monomer, which is prepared by conducting a polymerization in a manner such that at least half amount of the methallyl sulfonic acid monomer to be used is added to the polymerization system in a substantial period of adding the sulfo group-containing vinyl monomer having a higher reactivity ratio than acrylonitrile to the system. The acrylonitrile polymer is suitable for the preparation of a modacrylic synthetic fiber, and the modacrylic fiber prepared therefrom has excellent flame resistance, devitrification preventing property and dyeing affinity.

Abstract: A process for the emulsion polymerization of one or more polymerizable monomers wherein the emulsion polymerization is carried out in the presence of an emulsifier in the form of a diacid of a cyclic alkane or alkene. Emulsifiers of that type have been found to provide improved latex stability, improved bloom and improved processability of the resulting polymer.

Abstract: What are disclosed are a method for making an emulsion polymer by polymerizing water insoluble free-radically polymerizable monomers, or monomer mixtures predominantly comprising such monomers, by emulsion polymerization in the presence of a polymerization initiator which is soluble in organic solvents and has at least limited solubility in water, and in the further presence of a free non-polymerizable emulsifying acid, also soluble in organic solvents, and the conversion of such an emulsion polymer by spray drying into a polymer powder which is completely soluble in organic solvents to form clear solutions from which polymer films of reduced water sensitivity can be formed.

Abstract: The invention relates to a process for the continuous production of a chemically uniform copolymer comprising 15 to 50% by weight of acrylonitrile and from 85 to 50% by weight of vinyl chloride and, optionally, up to 4% by weight of at least one other copolymerized ethylenically unsaturated comonomer containing acid groups by emulsion polymerization, wherein the copolymerization reaction is carried out with a monomer ratio of acrylonitrile to vinyl chloride of from 0.02 to 0.5, in the presence of a redox catalyst and in an acidic medium.

Abstract: A process for the preparation of copolymers of styrene and/or its derivatives by polymerization of one or more aromatic monovinyl compounds and acrylonitrile and/or methacrylonitrile wherein up to 75% by weight of the monomer mixture may be replaced by C.sub.1 --C.sub.20 -alkyl esters of acrylic and/or methacrylic acid and polymerization is carried out in the presence of from 0.01 to 10% by weight, based on the total quantity of monomers, of one or more enol ethers derived from aliphatic or cycloaliphatic aldehydes or ketones.

Abstract: A method for stopping and restarting the free-radical polymerization of vinyl monomers (e.g. acrylic monomers) without forming low molecular weight polymer is provided. These polymerizations utilize a Redox catalyst system comprising multivalent metal ions (e.g. iron ions) as promoter. The polymerizations are stopped by chelation of the iron present. Additional monomer is added to the polymerization to avoid formation of low molecular weight polymer. Upon restart metal ions are added to the polymerization mixture.

Abstract: There are disclosed polymerizable alkyl poly(oxyalkylene) esters of an acrylate oligomer and copolymers thereof, especially stable, aqueous dispersions of water-insoluble emulsion copolymers of (1) about 10-70% by weight of methacrylic or acrylic acid, (2) about 0.5-25% by weight of an alkyl poly(oxyalkylene) ester of an acrylate oligomer, and (3) at least 25% by weight, to a total of 100%, of a C.sub.1 -C.sub.4 alkyl (meth)acrylate, and optionally, included in the total monomer mixture, a small amount of (4) about 0.5-1% by weight, of a polyethylenically unsaturated monomer. The copolymers, when neutralized and solubilized by addition of an alkali, are high efficiency thickeners for aqueous systems and have improved tolerance to ionic or electrolyte content. Typical systems that can be thickened are paint latices, cosmetic preparations, food preparations, ionic detergents, dye pastes for textiles, pharmaceuticals, and oil well drilling muds.

Abstract: In the emulsion polymerization of a monomer mixture comprising an aromatic vinyl compound, a vinyl cyanide compound and if desired, other vinyl compounds copolymerizable therewith in an aqueous medium, the vinyl cyanide compound is further added to the polymerization system in a controlled velocity during the substantial period of polymerization from the initial stage. When the copolymer thus obtained is incorporated into, for example, an acrylonitrile-butadiene-styrene terpolymer composition, thermoplastic resin compositions not coloring upon molding are obtained with a good impact resistance and heat resistance.

Abstract: Process for preparing copolymers of vinyl-aromatic monomers with ethylenically unsaturated nitriles having a very low content of unreacted residual monomers, consisting in adding to the polymerization dispersion, containing a compound capable of giving free radicals, and in the final step of the polymerization process, from 0.2 to 2% by weight of a comonomer which is reactive towards the unreacted monomers.

Abstract: This invention relates to .alpha.-olefin-acrylonitrile copolymers and uses thereof, particularly as antistatic agents in organic liquids such as hydrocarbon fuels.

Abstract: The tendency to crosslink of polymer compositions comprising polymer units derived from acrylonitrile and maleic anhydride is controlled by the use of an acid ester of a phosphorus acid.

Abstract: Acrylonitrile polymers and copolymers with good affinity for basic dyes without sulfonic acid groups containing comonomers are obtained by polymerizing at a temperature of from 0.degree. to 60.degree. C. in an aliphatic hydrocarbon having a boiling point of from -10.degree. to 80.degree. C. or in a mixture of aliphatic hydrocarbons having boiling points in the range from -10.degree. to 80.degree. C. using an initiator system comprising from 0.1 to 8.0 mole percent of sulfur dioxide, from 0.1 to 2.0 mole percent of a hydroperoxide which is soluble in the reaction medium and from 0.01 to 1.0 mole percent of an acid which is soluble in the reaction system in that polymerization is carried out continuously and in that an average residence time of from 10 minutes to 2 hours is maintained.

Abstract: A method for determining the amount of copolymerized vinyl monomer in a acrylonitrile/vinyl monomer copolymer is provided. The method is based on the fact that increasing the vinyl monomer content of the copolymer reduces its melting point. The method consists of first determining the melting point of the copolymer while the copolymer is saturated with water. The presence of water reduces the melting point to a temperature below the range where thermal degradation of the copolymer occurs. The amount of copolymerized vinyl monomer in the copolymer can then be determined by comparing its melting point in the presence of water to that of corresponding copolymers in which the vinyl monomer content thereof is known and varies from copolymer to copolymer.

Abstract: In the emulsion polymerization of an .alpha.-alkylstyrene and an unsaturated nitrile copolymerizable therewith in a weight proportion of 70:30 to 80:20 in the presence of a radical initiator, an improved process wherein the monomers are introduced into the reaction system in such a manner that the concentration of the unreacted unsaturated nitrile in the reaction system is not less than 31% by weight to the entire amount of the unreacted monomers in the reaction system at the completion of the introduction of the monomers, whereby a copolymer of the .alpha.-alkylstyrene and the unsaturated nitrile having an excellent thermal resistance is produced with marked decrease in the amount of unreacted monomers.

Abstract: An improved process for the preparation of copolymers of .alpha.-methylstyrene and other co-monomers such as acrylonitrile styrene, methyl methacrylate and the like, wherein a substantially water-immiscible softener is employed, particularly prior to coagulation of the latex formed of the copolymer, whereby an improved product of higher bulk density and easier to employ in a subsequent processing is obtained.

Abstract: The invention relates to a process for the production of a chemically uniform acrylonitrile vinyl chloride copolymer in an aqueous emulsion in the presence of a redox catalyst and with a fluctuating concentration of at least one iron salt in the reaction medium wherein the polymerization reaction is carried out at a pH value of from 2 to 6 in the presence of a mixture of an iron salt and a complex former, the complex former having certain apparent stability constants of the iron-II-complex and of the iron-III-complex.

Abstract: The invention relates to a homopolymer or copolymer of acrylonitrile which comprises from 0 to 30% by weight, incorporated by polymerization, of comonomer units which are free from ionic groups, said polymers having a K-value of from 50 to 100, a dye absorption capacity for cationic dyes of at least 0.5% by weight, a conductivity, measured in dimethylformamide solution, of at least 10.mu. Siemens, and from 0.2 to 1.5% by weight of sulphur fixed to said polymer as well as to a process for the production thereof.

Abstract: A process and apparatus for preparing vinyl polymers by continuous bulk or solution polymerization provide improved mixing during polymerization. In the process, fresh polymerization starting material is incorporated into a part of reaction mixture withdrawn from a polymerization zone and then fed to the polymerization zone. Polymerization temperature is kept at 100.degree. to 200.degree. C. and polymer content in a reaction mixture withdrawn from the polymerization zone is kept at 50 to 80% by weight. A tank having agitating means, outlet opening and recycling inlet is used as polymerization reactor. Said recycling inlet is preferably located at a position corresponding to 1/4 or less of the total height from the bottom to the top of the tank.

Abstract: There is provided a process and apparatus for the coagulation of an aqueous latex of a polymer wherein the latex and an aqueous coagulant are mixed in a tubular coagulation means which is disposed at an angle of from about 20.degree. up to 90.degree. to the horizontal plane and the coagulated mixture is passed from the tubular coagulation means to a conduit equipped with an impingement plate and then to means for separation, recovery and drying of the coagulated polymer.

Abstract: There is provided a process and apparatus for the coagulation of an aqueous latex of a polymer wherein the latex and an aqueous coagulant are mixed in a tubular coagulation means and the essentially completely coagulated mixture therefrom is passed into one or two vessels containing aqueous coagulant followed by separation, recovery and drying of the coagulated polymer.

Abstract: A process for preparing a thermoplastic resin having high heat resistance by emulsion polymerization of an .alpha.-alkylstyrene compound of the formula: ##STR1## wherein R.sub.1 is C.sub.1 -C.sub.3 alkyl and R.sub.2 is hydrogen, C.sub.1 -C.sub.3 alkyl or halo(C.sub.1 -C.sub.3)alkyl and an unsaturated nitrile in a weight proportion of 65:35 to 80:20 in the presence of a radical initiator, characterized in that the whole amount of the .alpha.-alkylstyrene compound and 10 to 99% by weight of the unsaturated nitrile on the basis of its total amount are first subjected to polymerization and, after the polymerization, the remaining portion of the unsaturated nitrile is added to the reaction mixture and the resultant mixture is subjected to further polymerization until the polymerization is substantially completed.

Abstract: Water-hardening binding agent such as concrete, mortar, cement and the like are modified with a solid additive in the form of aggregates consisting of fine particle having a grain size of from 0.1 to 10 mm, preferably in pelletized or pressed grain form. These additives have an adjustable rate of dissolution and permit controlling the speed and manner of hardening of said water-hardening binding agent.