MXPA97001507A - Procedure for the obtaining of latices basede dienos conjugados by polimerizacion poremuls - Google Patents

Abstract

The present invention relates to a process for the preparation of latexes based on butadiene and / or isoprene and / or chloroprene and optionally vinyl compounds copolymerizable therewith by means of emulsion polymerization, characterized in that the monomers to be polymerized are dosed. to the seed latex arranged in advance with a particle size of 10 to 80 nm, based on the monomers used in the process according to the invention or on inorganic pigments, in the presence of a radical-forming activator and an emulsifier, in such a way that the ratio between the polymerization rate of the monomers and the feed rate of the monomers is from 0.05 to 0.7: 1, the polymerization being carried out until a conversion of the monomers of 295% at temperatures of 10 to 85§C, controlling the dosage of the emulsifier in such a way that the final particle size (TGL) of the latex to be manufactured is sealed by the following equation: TGL = TGS x (mL / DL) 1/3 ((ms / DS) 1/3, with DL = Density of the latex particles in the latex to be manufactured, DS = Density of the particles in the sowing used mL = Mass of the latex particles in the latex to be manufactured ms = Mass of the particles in the sowing used, TGL = Size of the latex particles to be manufactured, TGS = Size of the particles of the sowing used, and the amount of emulsifier being from 0.1 to 10% by weight, based on the total amount of monomers used, the ratio of the conjugated dienes mentioned above in the copolymers assuming a value of > -15% by weight, the ratio of the comonomers containing vinyl groups to a value of > -85% by weight and the amount of seed previously prepared, a value of 0.01 to 15% by weight, based on the total amount of the monomers used

Description

PROCEDURE FOR THE OBTAINING OF LATICES BASED ON DIENOS CONJUGADOS BY POLYMERIZATION BY EMULSION. Description of the invention The present invention relates to a process for obtaining latices based on conjugated dienes by emulsion polymerization. the latices obtained according to the process of the invention are especially suitable for the manufacture of immersion articles, such as gloves, of synthetic leather, of coatings, such as coating for the back of carpets, coating for paper and coating for leather. For the production of latexes by emulsion polymerization, batch, semi-continuous and continuous processes are known in the literature. Semi-continuous processes will be understood as both the monomer feed methods and the seed / monomer feed procedures. In the latter case the seeding can be formed either in the first stage of the process (internal seeding) or it can be added to the polymerization as a separately manufactured seeding (external sowing). In general, the batch processes have the disadvantage that, for example, slight deviations of the temperature or of the raw materials with respect to the theoretical quantities lead to clear oscillations of the number of particles, which in turn has a REF marking: 24197 effect on the polymerization rate. The feeding methods have, compared to the batch processes, the advantage, in terms of safety in production, that only a part of the total amount of the monomers is added during the polymerization. Compared with the batchwise process, however, in the case of homo or copolymers of conjugated dienes, highly crosslinked polymers are a disadvantage for certain applications. The task of the present invention therefore consists in providing a method that avoids the aforementioned disadvantages of the batch process and the aforementioned drawbacks of the feeding process. In this way, latices having, for example, a low degree of branching and / or crosslinking as well as a high expansion at break will be obtained according to the process of the invention. Furthermore, the process according to the invention must have a high reproducibility and thus minimize the formation of secondary products (such as, for example, Diels-Alder products). The object of the present invention is therefore a process for the preparation of latices based on butadiene and / or isoprene and / or chloroprene and, where appropriate, vinyl compounds copolymerizable therewith by means of emulsion polymerization, characterized in that the monomers to be polyered are metered into the seed latex arranged in advance with a particle size of 10 to 80 nm, based on the monomers used in the process according to the invention or on inorganic pigments, in the presence of a radical-forming activator and an emulsifier, in such a way that the ratio between the polymerization rate of the monomers and the feed rate of the monomers is from 0.05 to 0.7: 1, the polymerization being carried out to a with-monomers version of > 95% at temperatures of 10 to 85 ° C, controlling the dosage of the emulsifier in such a way that the final particle size (TGL) of the latex to be manufactured is given by the following equation: with DL = Density of the latex particles in the latex to be manufactured Ds = Density of the particles in the sowing used mL = Mass of the latex particles in the latex to be manufactured ms = Mass of the particles in the sowing used TGL = Size of the latex particles to be manufactured TGS = Size of the seed particles used, and the amount of emulsifier being from 0.1 to 10% by weight, based on the total amount of monomers used, assuming the proportion of the conjugated dienes mentioned above in the copolymers a value >15% by weight, the proportion of the comonomers containing vinyl groups a value of < 85% by weight and the amount of seed previously prepared, a value of 0.01 to 15% by weight, based on the total amount of monomers used. As other monomers, which can be copolymerized with the aforementioned conjugated dienes, compounds containing vinyl groups can be used in the process according to the invention. Examples which may be used are compounds containing vinyl groups: acrylonitrile, methacrylonitrile, dichlorobutadiene, a-methylstyrene, styrene, esters of asrrolic acid, esters of methacrylic acid, vinylcarboxylic acids, such as methacrylic acid, acrylic acid, acid fumaric acid and itaconic acid as well as methacrylamide and / or acrylamide. In addition, vinyl compounds with N-methylolamide groups and / or their ester or ether derivatives can be used as monomers. Mention may be made of: N-methylolacrylamide, N-methylolmethacrylamide, N-methoxymethyl (meth) acrylamide, N-n-butoxymethyl- (meth) acrylamide and / or N-acetoxymethyl- (meth) acrylamide. In addition, those with a sulfonic acid group and / or a sulfonate group can be used as vinyl compounds. Mention may be made of: styrenesulfonic acid, vinylsulphonic acid, allylsulfonic acid, methanesulfonic acid, 3-sulfopropyl (meth) acrylate, 2-acrylamido-2-methylpropanesulfonic acid, which may be used, if appropriate, in the form of their water-soluble salts, preferably 3-sulfopropyl (meth) acrylate and 2-acrylamido-2-methyl-propanesulfonic acid. According to the process of the invention, it is possible to obtain both homopolymers based on the conjugated dienes mentioned above and copolymers based on the mentioned conjugated dienes with the aforementioned comonomers susceptible to copolymerization. The proportion of the conjugated dienes in the copolymers is usually at a value of > 15% by weight, preferably from 20 to 99% by weight. The proportion of the comonomers containing vinyl groups usually amounts to a value of < 85% by weight, preferably 80 to 1% by weight. In the case of copolymerization, the quantitative ratio of the monomers used to each other depends on the desired application purposes in each case of the lacquers to be manufactured. The optimum quantitative ratio of the monomers to one another can easily be determined by means of corresponding preliminary tests and for example can be deduced according to the indications given in EP-A 0 442 370, page 4, lines 13-26. The process according to the invention is especially suitable for the production of diene polymers and -copolymers (I), which have, for example, the following monomer compositions (the percentages by weight give a total of 100): to 100% by weight, preferably 90 to 100% by weight of butadiene, isoprene and / or chloroprene, Ib) 0 to 10% by weight, preferably 0 to 5% by weight of vinylcarboxylic acid, le) 0 to 10% by weight , preferably 0 to 5% by weight of acrylonitrile, methacrylonitrile, styrene, methyl methylen, esters of methacrylic acid, esters of acrylic acid and / or vinyl compounds with sulfonate, sulphonic acid, amide and / or N groups -methylolamide; as well as for obtaining latices (N) SBR (II) for example with the following composition: a) 15 to 99% by weight, preferably 20 to 99% by weight of butadiene and / or of isoprene, Ilb) 1 to 80 % by weight, preferably 1 to 60% by weight of acrylonitrile, methacrylonitrile, styrene, α-methylstyrene and / or methyl methacrylate, from 0 to 25% by weight of esters with 2 to 8 carbon atoms of the acid (meth) acrylic, lid) from 0 to 10% by weight of vinylcarboxylic acids, from 0 to 15% by weight of vinyl compounds with sulfonate, sulphonic acid, amide and / or N-methylolamide groups. As the seed, for example, latices according to the invention are suitable, based on the latices to be manufactured according to the process of the invention as well as on the basis of latices based on other monomers different from those of the latices to be manufactured. Examples which may be mentioned are: latices based on styrene and / or acrylonitrile and / or methyl methacrylate and / or butadiene and / or one of the vinylcarboxylic acids already mentioned above. Preferably, latices of styrene or butadiene based oatlets are used as seed latexes., latices of carboxylated copolymers based on styrene or methyl methacrylate as the main monomer as well as the vinylcarboxylic acids mentioned above as comonomers. The size of the seed particles set beforehand is in the range of 10 to 80 nm, preferably in the range of 20 to 50 nm. As a seed, for the process according to the invention, it is also possible to use those inorganic pigments whose particles can act as germs for the subsequent polymerization. For example, pigments with an average particle size of 5 to 100 nm, such as silica sol, whose use has been described in the literature as seed for emulsion polymerization (Hergeth, Starre, Schmutzler, artewig) are suitable. , Polymer, 1988, Vol. 29, 1923-8, Furusawa, Kimura, Tagawa, J. Colloid Interface Sci., 1986, 109 (1), 69-76). According to the method of the invention, the total amount of the sowing to be used or also only a corresponding partial amount of the sowing to be used in total can be arranged in advance. The remaining amount of sowing can be further dosed during the course of the polymerization. Preferably, in advance, according to the method of the invention, the total amount of seeding in the monomers to be polymerized will be arranged in advance. The amount of the sowing to be added depends on the size of the latex to be manufactured and can be determined by the equation (I) above. This usually amounts to 0.01 to 15, preferably 0.1 to 5% by weight, based on the total amount of the monomers, with a particle size of 10 to 80 nm. For the process according to the invention, it is essential that the ratio between the polymerization rate of the monomers and the feed rate of the monomers is less than 0.7: 1, preferably from 0.05 to 0.7: 1, especially from 0.05 to 0.6: 1. The polymerization of the monomers used will be carried out according to the process of the invention, in the presence of a radical-forming activator, of an emulsifier and in the presence of water. As radical-forming activators, the process according to the invention can be used, for example, peroxo-inorganic compounds, such as hydrogen peroxide, sodium peroxodisulfate, potassium and ammonium peroxides, peroxocarbonates and hydrates of borate peroxide, in addition peroxo-organic compounds, such as acylhydroperoxides, diacylperoxides, alkylhydroperoxides and dialkylperoxides, as well as esters, such as tere perbenzoate. -butyl, as well as combinations of inorganic and organic activators. The amounts of activator are usually in the range of 0.01 to 5% by weight, based on the total amount of monomers used, preferably in the range of 0.05 to 2.0% by weight. The mentioned inorganic and organic peroxo compounds (activators) can also be used in combination with one or more suitable reducing agents in a known manner. Examples of such reducing agents include: sulfur dioxide, alkali disulfites, hydrogensulfites, potassium sulfate, dithionite and formaldehyde sulfoxide ammonium, hydroxylamine hydrochloride, hydrazine sulfate, ferrous sulfate (II), glucose and ascorbic acid. The amount of reducing agent is from 0.01 to 1.0% by weight, based on the total proportion of monomers. By means of corresponding preliminary tests, the suitable activator can be optimally determined. This depends in particular on the type of monomers used and on the reaction temperature of the polymerization. It is often advisable to carry out the emulsion polymerization further in the presence of buffer substances as well as chelating agents. For example, alkali metal phosphates and pyrophosphates (buffer substances) and alkali metal salts of ethylenediaminetetraacetic acid (EDTA) are suitable as chelating agents. The amount of buffer substances and chelating agents is usually 0, 01 to 1% by weight, based on the total amount of monomers. In addition, chain-terminating agents (regulators) are frequently used for the emulsion polymerization. For example, organic sulfur compounds, such as alkylmercaptans with 1 to 15 carbon atoms, with n-, i-, and t-dodecyl mercaptan being preferred. The amount of the chain-breaking agent is usually from 0.05 to 3% by weight, preferably from 0.2 to 2.0% by weight, based on the total weight of the monomers used. For the emulsion polymerization according to the invention it is also significant that the dosage of the necessary stabilizer and / or the emulsifier is controlled in such a way that the final particle size of the finished latex is derived from the aforementioned equation. Emulsifiers are known and are used in the usual manner in emulsion polymerization (D.C. Blackley, Emulsion Polymerisation, Chapter 7, Applied Science Publishers LTD, London 1975). Suitable emulsifiers to be used according to the invention are: so-called anionogenic emulsifiers, such as sulfates of higher fatty alcohols, higher alkylsulfonates, alkylarylsulphonates, arylsulfonates as well as their condensation products with formaldehyde, salts of the esters of sulfosuccinic acid and sulphated adducts of ethylene oxide. Furthermore, they are known as non-iogenic emulsifiers, such as, for example, the known reaction products of ethylene oxide with fatty alcohols, such as lauryl, myristyl, cetyl, stearyl and oleic alcohol, with fatty acids, such as lauric acid, myristic acid, co, palmitic, stearic and oleic, as well as their amides, and with alkylphenols, such as isooctyl-, isononyl- and dodecylphenol. For the polymerization in the alkaline pH range, the salts of the fatty acids and the colophonic acids are particularly suitable. Said emulsifiers are generally used in amounts of 0.1 to 10% by weight, in particular 0.2 to 8% by weight, based on the total amount of the monomers. The total amount of the monomer to be used is determined such that the latex is stabilized during the polymerization such that no coagulates are formed. On the other hand, the emulsifier can not be added in too large a quantity or at too premature a stage since, in other case, new latex particles would be formed which would result in an uncontrolled increase in the polymerization speed. By controlling the final size of the particles, calculated according to equation (I) from the amount used and the size of the seed particles, it can be easily verified whether the dosage of the emulsifier is carried out in such a way that new latex particles are formed or an agglomeration of the particles originally present does not take place. The amount to be used for water in the emulsion polymerization will usually be sized so as to result in a concentration of solid matter of the latex in water of 40 to 55% by weight. The process according to the invention is especially suitable for the production of acrylonitrile-butadiene copolymer latexes. For the preparation of acrylonitrile-butadiene copolymer latices, preferably from 15 to 60% by weight of acrylonitrile and / or methacrylonitrile, from 39 to 84% by weight of butadiene, from 0 to 10% by weight of one of the vinylcarboxylic acids mentioned as well as 0 to 25% by weight of an ester of acrylic acid and / or methacrylic acid and / or styrene and 0 to 15% by weight of a vinyl compound with a sulfonate, amide or N-methylol amide group and / or N-methylolamide etherified and / or esterified. The preparation of the acrylonitrile-butadiene copolymer latexes will be carried out in this case in the presence of a redox activator based on peroxo-compounds with suitable reducing agents. In this respect, redox activators based on hydroperoxides are particularly suitable., such as cumol hydroperoxide, hydroperoxide diisopropylbenzene or t-butyl hydroperoxide in combination with alkaline formaldehyde sulfoxylates or disulfites as reducing agents. Preferably, the polymerization is carried out in the presence of small amounts (0.0001 to 0.1% by weight, based on the total amount of the monomers used) of ferrous salts II, optionally with addition (up to 0.5 % by weight) of a complexing agent, such as for example EDTA. In order to obtain the acrylonitrile-butadiene copolymer latexes, it has proven advantageous to carry out the polymerization firstly up to a conversion of the monomers of up to 60%, preferably up to 70%, at temperatures of 10 to 60. ° C and then bring it to completion at a temperature 10 to 20 ° C higher (referred to the temperature chosen in the first part) (up to a maximum of 80 ° C) until a conversion of >95%, preferably > 98%. For the polymerization one or more emulsifiers will be added in such a way that the growing particles of the latex are stable and the final size of the particles of equation (I) is deduced. Preferably, according to the process of the invention, acrylonitrile-butadiene copolymer lattices with particle sizes in the range of 80 to 200 nm are produced. The total amount of emulsifiers used will be chosen in such a way that no coagulates are formed during the polymerization. Depending on the size of the desired particles, in this case, from 1 to 8% by weight of emulsifiers, based on the total amount of the monomers used, will be required according to the invention. The process according to the invention has the following advantage: it represents an almost free polymerization of coagulates with an excellent reproducibility of particle size and polymerization rate even in the case of critical compositions of monomers, whose polymerization can only be control with difficulty and reproduce with difficulty according to the current state of the art. In this context, for example, the polymerization of copolymer latices of acrylonitrile with butadiene with an acrylonitrile content > 40% by weight. With regard to the application properties of the latices, the following advantages should be highlighted in relation to traditional methods: High refractive indexes, high tensile strengths as well as good wear properties due to friction of the dried polymerization films, manufactured from them, both in the non-crosslinked state and also in the vulcanized state, in case this is desirable for the application. In addition, the latices manufactured according to the invention are characterized, compared to the latices made with conjugated dienes in the batch process, by a lower content of undesirable by-products of Diels-Alder.

The latexes manufactured according to the process of the invention based on conjugated dienes find application especially in the manufacture of immersion articles and materials based on synthetic leather in the union of fibers of all kinds as well as in the coating of paper, leather, textiles, non-woven or reverse carpet fabrics. The sizes of the particles indicated in the examples were determined by means of laser correlation spectroscopy. For the seed latexes, a particle size distribution was additionally plotted with the ultracentrifuge and the average particle size number (TGs) at 37 nm was determined. The density of the seed particles used in the seed latexes was 1.06 g / cm in all the examples. In the indicated examples, samples were taken during the polymerization and the corresponding conversion of the polymerization was calculated from the solid matter determined by concentration by evaporation. From the conversion determined at the time of the complete dosing of the monomers, the relationship between the polymerization rate and the feed rate (V (poly <l) was determined: V (alim #)). Examples Example l. 40 g of a 30% sowing latex are heated (particle size 37 nm) in an autoclave, flushed with nitrogen, with 302 g of water at 80 ° C and fed, within 2 hours, a monomer / regulator mixture consisting of 368 g of styrene, 600 g of butadiene, 20 g of acrylic acid as well as 10 g of t-DDM (tertiary dodecylmer-captan). Parallel to this, an emulsifier feed consisting of 8 g of sodium dodecylbenzenesulfonate, 1 g of sodium hydroxide, 1 g of ammonium persulfate and 450 g of water is dosed. After 2 hours, an activator feed is started for 8 hours consisting of 3 g of ammonium persulfate and 60 g of water. During the whole polymerization the temperature was 80 ° C. After a total polymerization time of 15 hours, the concentration, determined by concentration by evaporation, was 54.4%, which corresponds to the conversion of 98.9%. The ratio between the polymerization rate and the feed rate of the monomers was 0.25: 1. The size of the particles was determined with a value of 163 nm (calculated 167 nm). Comparative Example 1. 40 g of a 30% sowing latex are heated (particle size 37 nm) in a nitrogen-swept autoclave with 302 g of water at 80 ° C and a monomer / regulator mixture consisting of 368 g of styrene, 600 g of butadiene, 20 g of acid is dosed. acrylic as well as 10 g of t-DDM, in the course of 12 hours. Parallel to this, an emulsifier feed consisting of 8 g of dodecylbenzenesulfonate -? 7-sodium, 1 g of sodium hydroxide, 1 g of ammonium persulfate, and 510 g of water for 12 hours. During the whole polymerization the temperature was 80 ° C. After a total polymerization time of 18 hours, the concentration was 54.6%, determined by evaporation concentration, corresponding to a conversion of 99.2%. The ratio between the polymerization rate and the feed rate of the monomers was 0.80: 1. The size of the particles was determined with a value of 169 nm (calculated 167 nm). Properties of films made with latices: 1) According to DIN 53 504. Example 2. 67 g of a 30% sowing latex is heated (particle size 37 nm) in a nitrogen-swept autoclave, with 853 g of water, 0.5 g of ethylenediaminetetraacetatetesodic (Na4EDTA), 0.05g of sodium formaldehyde sulfoxylate, as well as 0.05g of ferrous sulphate. -II at 40 ° C, 1.0 g of t-butyl hydroperoxide is added and a monomer / regulator mixture consisting of 450 g of acrylonitrile, 480 g of butadiene, 40 g of methacrylic acid as well as 5 g of t-DDM in the course of 3 hours. Parallel to this, the emulsifier / activator mixture consisting of 30 g of sodium laurisulphate is dosed., 0.5 g of sodium aldehyde sulfoxylate as well as 280 g of water over the course of 5 hours. After a total polymerization time of 15 hours at 40 ° C, the concentration was 46.3%, determined by evaporation concentration, which corresponds to a conversion of 99.4%. The ratio between the polymerization rate and the feed rate of the monomers was 0.22: 1. The particle size was determined with a value of 134 nm (calculated 138 nm). Comparative example 2a. 67 g of a 30% sowing latex (particle size 37 nm) are heated in a nitrogen swept autoclave, with 853 g of water, 0.5 g of Na4EDTA, 005 g of sodium formaldehyde sulfoxylate, as well as 0 , 05 g of ferrous sulphate-II at 40 ° C, 1.0 g of t-butyl hydroperoxide is added and a monomer / regulator mixture consisting of 450 g of acrylonitrile, 480 g of butadiene, 40 g of acid is dosed. methacrylic as well as 5 g of t-DDM, in the course of 12 hours. Parallel to this, a sample of emulsifier / activator consisting of 30 g of sodium lauryl sulphate, 0.5 g of sodium formaldehyde sulfoxylate and 280 g of water is metered in over the course of 12 hours. After a total polymerization time of 15 hours at 40 ° C, the concentration was 46.1%, determined by concentration by evaporation, which corresponds to a conversion of 98.9%. The ratio between the polymerization rate and the feed rate of the monomers was 0.81: 1. The particle size was determined with a value of 145 nm (calculated 138 nm). Comparative examples 2b and 2c. They are heated in an autoclave swept with nitrogen, 950 g of water, 7.5 g of sodium lauryl sulfate, 0.5 g of Na4EDTA together with a monomer / regulator mixture consisting of 450 g of acrylonitrile, 510 g of butadiene, 40 g of methacrylic acid as well as 5 g of t-DDM at 40 ° C. It is activated with a solution of 0.05 g of sodium formaldehyde sulfoxylate, 0.05 g of ferrous sulfate-II in 50 g of water as well as by the addition of 1.0 g of t-butyl hydroperoxide and polymerized at 40 ° C. C. A solution of 11.25 g of sodium lauryl sulfate, 0.125 g of sodium formaldehyde sulfoxylate in 90 g of water with a solids content determined by 15% concentrated samples as well as 30% evaporation is added respectively. In the case of the polymerization of comparative example 2b, initially an inhibition time of 3 hours was produced, after 23 hours the conversion was 99% and the particle size was 129 nm. In the case of comparative example 2c the polymerization started immediately and reached a conversion of 99.5% after 12 hours, the particle size was only 100 nm. Comparison of the properties of the polymer of Example 2 with those of Comparative Examples 2a, 2b and 2c. 1 'Vulcanization paste at 16.0% by weight (1.5% by weight of zinc oxide, 1.5% by weight of sulfur, 0.6% by weight of zinc N-diethyldithiocarbamate, 0.4% by weight of zinc mercaptobenzothiazole, 0.4% by weight of zinc N-pentamethylendithiocarbamate, 2.0% by weight of titanium dioxide, 0.48% of sodium salt of a condensation product of naphthalenesulfonic acid; % by weight of water) on 100% by weight of latex dry substance. Vulcanization 30 minutes in hot air at 105 ° C. ) according to DIN 53 504. 3) according to ASTM D 624. In Example 2, the preparation according to the invention of an acrylonitrile-butadiene copolymer latex with 45% by weight of acrylonitrile was described and compared with a process of feed according to the state of the art (comparative example 2a) as well as with a usual batch process (comparative example 2b, c). As a measure for the plastic deformation capacity of the latices, Defo hardnesses were determined for these latexes. In spite of approximately equal Defo values, the tensile strength, the expansion at break as well as the resistance to the propagation of the flaking of the vulcanized films of the polymer of example 2 are superior to the comparative example 2a. Compared to the comparative example 2b, the same level of values is reached, but the drawbacks of the poor reproduction capacity in the development of the polymerization and in the particle size of the final latex of comparative example 2b, c are avoided. .

Example 3. In example 3 and comparative examples 3a and 3b, the amount of regulator used for the polymerization was increased from 0.5 to 1.0% by weight, based on the monomers used, with relation to the examples 2, 2a or 2b. 67 g of a 30% seed latex (particle size 37 nm) are heated in an autoclave swept with nitrogen with 853 g of water, 0.5 g of Na4EDTA, 0.05 g of sodium formaldehyde sulfoxylate, as well as 0 , 05 g of ferrous sulfate-II at 40 ° C, a 1.0 g of t-butyl hydroperoxide is added and a mixture of monomers / regulator consisting of 450 g of acrylonitrile, 480 g of butadiene, 40 g of methacrylic acid as well as 10 g of t.DDM over the course of 3 hours. Parallel to this, the emulsifier / activator mixture consisting of 30 g of sodium lauryl sulphate, 0.5 g of sodium formaldehyde sulfoxylate and 280 g of water is metered in over 5 hours. After a total polymerization time of 15 hours at 40 ° C, the concentration was 46.4%, determined by evaporation concentration, which corresponds to a conversion of 99.4%. The ratio between the polymerization rate and the feed rate of the monomers was 0.20: 1. The size of the particles was determined with a value of 136 nm (calculated 138 nm).

Comparative example 3a. 67 g of a 30% seed latex (particle size 37 nm) are heated in an autoclave swept with nitrogen with 853 g of water, 0.5 g of Na4EDTA, 0.05 g of sodium formaldehyde sulfoxylate, as well as 0 , 05 g of ferrous sulphate-II at 40 ° C, 1.0 g of t-butyl hydroperoxide is added and a monomer / regulator mixture consisting of 450 g of acrylonitrile, 480 g of butadiene, 40 g of acid is dosed. methacrylic as well as 10 g of t-DDM over the course of 12 hours. Parallel to this, a mixture of emulsifier / activator consisting of 30 g of sodium lauryl sulphate, 0.5 g of sodium formaldehyde sulfoxylate and 280 g of water is metered in over 12 hours. After a total polymerization time of 15 hours at 40 ° C, the concentration was 46.0%, determined by concentration by evaporation, which corresponds to a conversion of 98.2%. The ratio between the polymerization rate and the feed rate of the monomers was 0.81: 1. The particle size was determined with a value of 138 nm (calculated 138 nm). Comparative example 3b. 950 g of water are heated in an autoclave flushed with nitrogen, 7.5 g of sodium lauryl sulfate, 0.5 g of Na4EDTA together with a monomer / regulator mixture consisting of 450 g of acrylonitrile, 510 g of butadiene, 40 g of methacrylic acid as well as 10 g of t-DDM at 40 g. ° C. It is activated with a solution of 0.05 g of sodium formaldehyde sulfoxylate, 0.05 g of ferrous sulfate-II in 50 g of water as well as by the addition of 1.0 g of t-butyl hydroperoxide and poly bristle at 40 ° C. A solution of 11.25 g of sodium lauryl sulfate, 0.125 g of sodium formaldehyde sulfoxylate in 90 g of water with a solids content, determined by concentration evaporated sample, of 15% as well as 30% is respectively added. In the conversion range between 50 and 70% the polymerization could not be controlled so that an uncontrolled temperature increase of 40 ° C to 55 ° C was observed. The polymerization was completed after 7 hours. The concentration of the latex was 46.7%, which corresponds to a conversion of 99.5%. The particle size was only 86 nm.

Comparison of the properties of the polymer of Example 3 with that of comparative examples 3a, 3b and 3c. 11 according to DIN 53 504 2) according to ASTM D 624 3) 16% by weight vulcanized paste (1.5% by weight of zinc oxide, 1.5% by weight of sulfur, 0.6% by weight of N- zinc diethyldithiocarbamate, 0.4% by weight of zinc mercaptobenzothiazole, 0.4% by weight of zinc N-pentamethylene dithiocarbamate, 2.0% by weight of titanium dioxide, 0.48% by weight of sodium salt of a condensation product of naphthalenesulfonic acid; 9.12% by weight of water) on 100% by weight of dry latex substance. Vulcanization 30 minutes in hot air at 105 ° C. The comparative example 3b, carried out according to the batch process, shows that the polymerization can not be controlled with this process. By comparing example 3 with comparative examples 3a and 3b it can be recognized that with the dosing of the onomers according to the invention, advantages were obtained in the properties of the polymeric films both in the non-crosslinked state and in the vulcanized state. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, the content of the following is claimed as property:

Claims (3)

1. CLAIMS 1.- Procedure for obtaining latices based on butadiene and / or isoprene and / or chloroprene and, if necessary, copolymerizable vinyl compounds with them by means of emulsion polymerization, characterized in that the monomers to be polymerized into the latex are dosed. With a particle size of 10 to 80 nm, based on the monomers used in the process according to the invention or on inorganic pigments, in the presence of a radical-forming activator and an emulsifier, in such a way that the ratio between the polymerization rate of the monomers and the feed rate of the monomers is from 0.05 to 0.7: 1, the polymerization being carried out to a conversion of the monomers of > 95% at temperatures of 10 to 85 ° C, controlling the dosage of the emulsifier in such a way that the final particle size (TGL) of the latex to be manufactured is given by the following equation:
2. TGL - TGS X (mL / DL) 1/3 ((ms / Ds) 1/3, with DL = Density of the latex particles in the latex to be manufactured Ds = Density of the particles in the sowing used mL = Mass of the latex particles in the latex to be manufactured ms = Mass of the particles in the sowing employed TGL = Size of the latex particles to be manufactured TGS = Size of the particles of the seeding used, and the amount of emulsifier being from 0.1 to 10% by weight, based on the total amount of monomers used, assuming the proportion of the conjugated dienes mentioned above in the copolymers a value of > 15% by weight, the ratio of the comondomers containing vinyl groups to a value of < 85% by weight and the amount of seed previously prepared, a value of 0.01 to 15% by weight, based on the total amount of monomers used. 2. Process according to claim 1, characterized in that the polymerization is carried out at temperatures of 20 to 80 ° C.
3. 3. Process according to claims 1 and 2, characterized in that the polymerization is carried out until a conversion of > 98%.