RU2160286C1 - Acrylonitrile/butadiene/styrene copolymer production process - Google Patents

Abstract

FIELD: polymer production. SUBSTANCE: acrylonitrile/butadiene/styrene copolymers containing up to 70 wt % of rubber product are prepared by graft copolymerization of styrene and acrylonitrile in absence of oxygen in water-emulsion medium in presence of preliminarily prepared butadiene-based rubber latex and under influence of radical-type initiator and in presence of molecular weight control agent (dodecylmercaptan or octylmercaptan) followed by distilling off unreacted monomers, coagulating resulting copolymer latex with aqueous coagulant solution, separating copolymer from aqueous medium, washing, and drying. Process is distinguished by adding hydrogen peroxide aqueous solution simultaneously with coagulant in amount determined by a math formula. EFFECT: copolymers have no unpleasant smell at processing temperatures above 180 C and retain a good compatibility with other polymers, possess increased impact resistance and improved workability. 4 cl, 2 tbl

Description

 The invention relates to the plastics industry, namely, the production of grafted acrylonitrile butadiene styrene (ABS) copolymers by water-emulsion polymerization. ABS copolymers are used as structural materials for the manufacture of cases and parts for radio and television equipment, the inner lining of household refrigerators, containers, packaging, etc. Grafted ABS copolymers containing more than 30 wt.% Rubber based on butadiene, also called "grafted rubber concentrates", are used to obtain compositions with high impact resistance, for example, for mixing with styrene-acrylonitrile copolymers (SAN copolymers), to modify the properties of ABS copolymers obtained by mass polymerization or suspension, as well as to modify other classes of plastic masses, namely polyamides, polyvinyl chloride, polycarbonates, etc.

Known [Baknell KB Shockproof plastics, L .: Chemistry, 1981, p. 87-89] a method for producing ABS copolymers, according to which styrene (ST) and acrylonitrile (AN) are polymerized in the presence of a preformed polybutadiene rubber latex to form a grafted copolymer. The grafting process takes place in an aqueous emulsion medium in the presence of an initiator - potassium persulfate and a molecular weight regulator (MM) -tret-dodecyl mercaptan (TDDM) at 50 ^o C in a nitrogen atmosphere up to 100% conversion. At the end of the process, a phenolic type antioxidant is introduced to prevent oxidative degradation during drying. The latex of the obtained grafted ABS copolymer is coagulated by adding an aqueous solution of calcium chloride (coagulant), the resulting grafted copolymer is washed with water and dried.

The disadvantages of the described method are:
1. The duration of the process associated with the polymerization at low temperatures (50 ^o C) and bringing the conversion of monomers to 100%. (As you know, it is with high conversion, especially above 95%, that the polymerization of ST and AN slows down dramatically).

2. The unpleasant smell of the obtained grafted ABS copolymer at processing temperatures (> 180 ^o C) or at elevated operating temperatures of products made from it, which is associated with the use of MM TDDM as a regulator during polymerization. The residual TDDM, which is a sufficiently high molecular weight compound, and its low molecular weight addition products, after washing and drying, remain in the obtained ABS copolymer. At normal temperatures, the copolymer has a relatively weak smell, but at elevated operating temperatures of products obtained from the ABS copolymer, and especially at processing temperatures (> 180 ^° C), the copolymer has a strong unpleasant odor.

Also known [application of Germany N 2525413, MKI C 08 F 279/04, publ. 02.01.76] a method for producing ABS copolymers by copolymerization of ST and AN in an aqueous emulsion medium in the presence of a preformed latex of polybutadiene rubber (polybutadiene or a copolymer of butadiene with styrene) under the action of a radical type initiator (2,2'-azo-bis-α, β-dimethyl-valeronitrile) in the presence of surfactants and the regulator MM - tertiary butyl mercaptan. The copolymerization process is carried out at 0-100 ^° C., preferably at 60 ^° C., in the absence of oxygen, for 6.5 hours. The copolymer yield is 80.3%. The obtained latex grafted copolymer is coagulated with a dilute solution of Al ₂ (SO ₄ ) ₃ at 92 ^o C, washed with water at room temperature and dried.

The use of tertiary butyl mercaptan, which is sufficiently volatile (boiling point 64.2 ^o C), as a MM regulator in the process, makes it relatively easy to remove it from latex during vacuum processing. Therefore, the obtained ABS copolymer has a faint odor (4.6 points on a ten-point scale; test samples are pressed at 180 ^o C and oriented in two directions).

The disadvantage of the process according to the application of Germany N 2525413 is the low yield of the copolymer (80.3%), due to the need for the process at a fairly low temperature (60 ^o C) due to the use of low-boiling regulator MM.

The closest set of essential features to the claimed method is the method described in RF patent N 2044008 (MKI C 08 L 55/02, publ. 09/20/95). In accordance with this method, ABS copolymers containing up to 70 wt.% Rubber based on butadiene, in particular grafted rubber concentrates, are obtained by graft copolymerization of a mixture of monomers - ST and AN in the absence of oxygen in an aqueous emulsion medium in the presence of preformed rubber latex on based on butadiene under the action of a radical type initiator in the presence of an MM regulator, dodecyl mercaptan or octyl mercaptan. The process is carried out with a stepwise rise in temperature from 60-68 ^o C to 75-80 ^o C to the conversion of monomers 95-98%. Unreacted monomers are distilled off, after which the obtained latex of the ABS copolymer is coagulated by adding an aqueous solution of a coagulant (aluminum sulfate), it is separated, the copolymer from the aqueous medium, washed and dried. The synthesis process can be either periodic or continuous.

 According to the described prototype method, ABS copolymers are obtained that are well combined with copolymers of SAN and ABS synthesized by bulk polymerization, or block-suspension method, as well as with polyamides, polycarbonates, and allow to obtain compositions with high impact resistance.

The disadvantage of the prototype method is that the resulting ABS copolymer has a strong unpleasant odor at elevated temperatures, in particular at processing temperatures (> 180 ^o C), which is associated with the use of MM regulator of normal or tertiary dodecyl mercaptan or octyl mercaptan, which, being sufficiently high molecular weight compounds are not removed from the copolymer during distillation of residual monomers and remain in the copolymer after washing and drying.

 The technical result, the achievement of which the present invention provides, is to obtain ABS copolymers that have virtually no unpleasant odor at processing temperatures and maintain good compatibility with other polymers, high impact resistance and improved processability.

где G H₂O₂ - количество перекиси водорода, которое необходимо ввести при коагуляции латекса, кг;
К - коэффициент, учитывающий содержание каучука в сополимере и равный 0,11 для сополимеров с содержанием каучука до 30 мас.% и 0,08 для сополимеров с содержанием каучука 30 - 70 мас.%;
[M] - количество вводимого регулятора молекулярной массы - додецилмеркаптана или октилмеркаптана, % от массы прививаемых мономеров и каучука (по сухому остатку латекса);
G_л - количество латекса сополимера, направляемого на коагуляцию, кг.The specified technical result is achieved due to the fact that in the method for producing ABS copolymers containing up to 70 wt.% Rubber, including grafted copolymerization of CT and AN in the absence of oxygen in an aqueous emulsion medium in the presence of a preformed butadiene rubber latex under the action of an initiator radical type in the presence of MM regulator - dodecyl mercaptan or octyl mercaptan, distillation of unreacted monomers, coagulation of the obtained latex ABS copolymer with an aqueous solution of a coagulant, separation with polymer from the aqueous medium, its washing and drying, the coagulation of the copolymer latex ABS- performed simultaneous administration in separate streams latex copolymer aqueous solution of the coagulant and an aqueous solution of hydrogen peroxide, wherein the amount of hydrogen peroxide to be incorporated in the coagulation of the copolymer latex is determined by the formula

where GH ₂ O ₂ - the amount of hydrogen peroxide, which must be entered during coagulation of latex, kg;
K is a coefficient taking into account the rubber content in the copolymer and equal to 0.11 for copolymers with a rubber content of up to 30 wt.% And 0.08 for copolymers with a rubber content of 30 - 70 wt.%;
[M] is the amount of molecular weight regulator introduced — dodecyl mercaptan or octyl mercaptan,% of the mass of grafted monomers and rubber (based on the dry residue of latex);
G _l - the amount of latex copolymer sent for coagulation, kg

The grafted copolymerization of CT and AN in an aqueous emulsion medium is carried out with a stepwise rise in temperature from 60-68 ^o C to 75-85 ^o C. Hydrogen peroxide is introduced in the form of an 8-15% aqueous solution. Simultaneously with aqueous solutions of coagulant and hydrogen peroxide, an emulsion of a thermal and / or light stabilizer is introduced in a separate stream.

It is known [Chichibabin A.E., Basic principles of organic chemistry, M., State Scientific and Technical. ed. Chem. literature, 1963, vol. I, p. 324-326], that the regulators MM - mercaptans widely used in the synthesis of rubbers and polymers based on styrene have a characteristic unpleasant odor, while higher mercaptans, such as dodecyl (lauryl) mercaptan (C ₁₂ H ₂₅ SH) or dodecantioli, have a relatively weak smell. Therefore, it is these higher mercaptans that have found application in the production processes of these polymers. However, as already mentioned above, dodecyl mercaptans, octyl mercaptans and their low molecular weight addition products, remaining in the finished polymer and evaporating at processing temperatures (above 180 ^o C), give the polymers a sharp unpleasant odor. The distillation of residual higher mercaptans and low molecular weight mercury addition products from styrene polymer latexes is a very difficult operation due to their high boiling point (t _boiling ). t _bale TDDM is 227-228 ^o C at 760 mm RT.article and 95-120 ^o C at 10 mm Hg. st .; t _{bales of} normal dodecyl mercaptan 124 ^o C at 5 mm Hg. st .; t _{bales of} octyl mercaptan 164-167 ^o C at 760 mm RT. Art. and 76-77 ^o C at 50 mm RT. Art. [Chemical Encyclopedic Dictionary, M.: Soviet Encyclopedia, 1983, p. 196, p. 406]. It is also known [US patent 4450261, MKI C 08 F 2/38, publ. 05.22.84] that in the synthesis of low molecular weight copolymers of styrene and maleic anhydride and their sulfo derivatives to reduce the smell of the resulting copolymer, instead of mercaptans, their derivatives are used - 3-mercaptopropionic acid or methyl-3-mercaptopropionate, which have higher boiling points than the corresponding mercaptans and therefore are less volatile. However, the use of such mercapto compounds can reduce the smell of the copolymer only at low temperatures, and at processing temperatures (above 180 ^o C) the copolymers have an unpleasant odor.

 It is known that odor reduction can be achieved by treating mercaptans with oxidizing agents, while weak oxidizing agents, such as hydroxylamine, sulfuric acid, and even oxygen in the presence of ammonia, oxidize mercaptans to disulfides, and strong oxidizing agents (nitric acid) oxidize mercaptans to sulfonic acids; these disulfides and sulfonic acids have higher boiling points than the corresponding mercaptans [Chichibabin A.E. The main principles of organic chemistry, M., State. scientific and technical ed. Chem. literature, 1963, T.I, p. 325-326].

In accordance with US patent 5521268 (MKI C 08 F 2/38, publ. 28.05.96] to eliminate the smell of mercaptans in copolymers of styrene, butyl acrylate and divinylbenzene, synthesized for use as a binder in toners, before synthesis, the mixture of monomers and the regulator MM - dodecantiol (dodecyl mercaptan) is held in atmospheric oxygen for 60 minutes, the resulting copolymer had no smell when heated to 230 ^o C. However, such a method of reducing odor is to treat the mixture of monomers and dodecyl mercaptan before copolymerization with air oxygen n for the preparation of ABS copolymers, since butadiene or styrene butadiene rubber in the presence of oxygen loses its ability to vaccinate.

 The authors of the present invention found that the introduction of an ABS copolymer into the latex during coagulation simultaneously with the coagulant by a separate stream of an aqueous solution of hydrogen peroxide (8-15%) leads to the almost complete disappearance of the unpleasant odor of the ABS copolymer at processing temperatures. The introduction of hydrogen peroxide in amounts determined by the above formula does not impair the physicomechanical properties of the resulting copolymer, while its processability even improves (melt flow rate increases). The introduction of a hydrogen peroxide solution into the latex of the ABS copolymer after distillation of the residual monomers before coagulation or after coagulation at the washing stage does not lead to the disappearance of the smell of the ABS copolymer at processing temperatures (see our counter, examples NN 4, 10 and 5, 11).

. Целесообразно применять каучуки, содержащие 60-80% гель-фракции со степенью набухания 10-25%. В соответствии с заявляемым способом в процессе используют предварительно полученные латексы каучука, которые могут быть получены как непосредственно перед синтезом АБС-сополимеров, так и заранее, т.е. могут применяться выпускаемые промышленностью латексы каучуков, такие как бутадиеновый AL-12 или бутадиенстирольный AL-10 с содержанием связанного стирола 10-12 мас.%.The inventive method can be obtained ABS copolymers containing from 15 to 70 wt.% Rubber based on butadiene, by periodic or continuous methods. As butadiene-based rubber, butadiene, styrene butadiene or nitrile butadiene rubbers or mixtures thereof in the form of aqueous latex with a particle size of 0.1-0.3 microns are used. (1000-3000

. It is advisable to use rubbers containing 60-80% gel fractions with a degree of swelling of 10-25%. In accordance with the inventive method, preformed rubber latexes are used in the process, which can be obtained immediately before the synthesis of ABS copolymers, or in advance, i.e. commercially available rubber latexes such as butadiene AL-12 or styrene butadiene AL-10 with a content of bound styrene of 10-12 wt.% can be used.

The grafted monomers —ST and AN are predominantly taken in a weight ratio of (75-50): (25-50). To increase the heat resistance of the resulting copolymer, part of the CT (up to 60%) can be replaced with alpha-methylstyrene (α-MCT). It is advisable to carry out the process of water-emulsion polymerization with a stepwise rise in temperature from 60-68 ^o C to 75-85 ^o C.

 The required amounts of initiator, emulsifier, MM regulator, thermal and / or light stabilizer are taken in% of the mass of grafted monomers and rubber (based on the dry residue of rubber latex).

 According to the claimed method, water-soluble peroxide initiators, such as potassium or sodium persulfate, can be used as an initiator. The initiator is taken in an amount of 0.05-0.25 wt.%.

 The regulator MM - dodecyl mercaptan (TDDM or normal dodecyl mercaptan - NDM) and / or octyl mercaptan is used in an amount of 0.2-1.0 wt.%.

 As an emulsifier in the implementation of the proposed method can be used potassium soap disproportionate rosin or soap of fatty carboxylic acids in an amount of 2-6 wt.%.

 During the synthesis process, light stabilizer additives are additionally introduced into the reaction medium, for example, Irganox 1520 (phenol, 2-methyl-4,6-bis [(octylthio) methyl] in an amount of 0.05-0.2 wt.%.

 After the synthesis of the ABS copolymer at the stage of distillation of the residual monomers, it is advisable to add a defoamer to the obtained latex, for example, KE-10-12, KE-10-26 emulsion (organosilicon-based aqueous emulsion).

 After the residual monomers are distilled off, the latex of the obtained ABS copolymer is subjected to stirring with coagulation with an aqueous solution of a coagulant, for example aluminum or magnesium sulfate, potassium alum or sulfuric acid.

 Simultaneously with the introduction of the coagulant solution into the latex of the ABS copolymer, a solution of hydrogen peroxide, preferably an 8-15% aqueous solution, is supplied in a separate stream. The amount of hydrogen peroxide supplied is determined by the above formula. In the case of a continuous copolymerization process, the calculated amount of hydrogen peroxide corresponds to the amount of hydrogen peroxide supplied to the coagulator for 1 h, and in the case of a batch process, the calculated amount of hydrogen peroxide corresponds to the amount of hydrogen peroxide supplied per 1 coagulation operation.

 At the coagulation stage, the necessary thermo- and / or light stabilizers are additionally introduced into the obtained ABS copolymer, such as Ionol (4-methyl-2,6-ditretic butylphenol), Irganox 1520 (phenol, 2-methyl-4,6-bis [( octylthio) methyl]), Irganox 245 (triethylene glycol bis-3- (3-tert-butyl-4-peroxy-5-methylphenyl) propionate).

After coagulation, the ABS copolymer powder is squeezed out on a vacuum filter, washed with hot water and dried at 70-110 ^o C.

 Obtained by the present method, the ABS copolymers can be directly used to obtain products for structural purposes (mainly copolymers with a rubber content of 15-30 wt.%), And to obtain mixtures with copolymers SAN and ABS, as well as with polyamides, polycarbonates, etc. .

The properties of the obtained ABS copolymers were determined as follows:
1. The melt flow rate (MFR) was determined according to GOST 11645-73 at 220 ^o C and a load of 10 kg (capillary with a diameter of 2.095 mm and a length of 8.0 mm).

2. The determination of the odor intensity of the ABS copolymer was carried out organoleptically. The scoring of the odor intensity using the excess sample method ("triangular test") using a five-point system was carried out similarly to the "Methodological guidelines for the hygienic assessment of the quality of polystyrene plastics", approved by the deputy. by Soyuzkhimplast A. Rybakov on July 4, 73, on ABS copolymer samples obtained on a device for determining PTR (IIRT) at 220 ^o C, 2-3 cm long and 2-2.5 mm in diameter. Samples were placed in a box (CB 34/12 according to GOST 7148-70) and presented to three experts for odor assessment.

 3. The butadiene content in the ABS copolymer was determined by the iodine-bromine method, and the amount of grafted copolymer (gel fraction) in the ABS copolymer was determined by selective dissolution by the methods described in the book "Analysis of Polymerization Plastics", L .: Chemistry, 1988, with. 168, 170.

 4. The degree of swelling of the gel fraction was determined in a solvent mixture of methyl ethyl ketone: acetone, taken in a ratio of 1: 1.

5. For ABS copolymers with a rubber content of up to 30 wt.%, Which can be used directly as structural materials, the following indicators were additionally determined:
- impact strength according to Izod according to GOST 19109-84;
- yield strength under tension in accordance with GOST 11262-80;
- elongation at break according to GOST 10262-80.

6. ABS copolymers with a high rubber content (more than 30 wt.%) Were mixed with SAN copolymer in a weight ratio of 30:70, respectively (with the addition of a stabilizer and plasticizer) in a Banbury type mixer, followed by extrusion and granulation. From the compositions, standard samples were cast on which the following were determined:
- impact strength according to Izod according to GOST 19109-84;
- yield strength under tension in accordance with GOST 11262-80;
- elongation at break according to GOST 10262-80.

 The invention is illustrated by the following examples.

Example 1
The preparation of the ABS copolymer by a continuous method in a cascade of 3 reactors (each reactor has a volume of 20 m ³ and is equipped with an impeller mixer).

In a mixer with a capacity of 1.2 m ³ , equipped with a two-bladed two-tier mixer, in separate flows continuously serves:
- 1555.56 kg / h of a mixture of monomers (hydrocarbon phase), consisting of 543.3 kg (28 wt.%) AN and 1001.2 kg (51.6 wt.%) ST and containing 11.06 kg (0, 57 wt.%) TDDM;
- 979.26 kg / h of aqueous latex of styrene-butadiene rubber (20.4 wt.%), With a dry matter content of 42%, containing 36.86 kg (2 wt.%) Of potassium soap disproportionate rosin;
- 4090.52 kg / h of demineralized water;
- 51.6 kg / h of a 3% aqueous initiator solution containing 1.55 kg of potassium persulfate (0.08 wt.%).

 The ratio of hydrocarbon and aqueous phases is 1: 2.5.

The mixing of all components is carried out at (25 ± 5) ^o C and a stirrer rotation speed of 100 rpm.

From the mixer, the finished reaction mixture at a speed of 6670 kg / h is continuously fed to the first reactor of the cascade, where the grafted copolymerization of CT and AN occurs at 60 ^° C until the conversion of monomers to 85% (the residence time of the reaction mixture in the reactor is 3 hours). The obtained latex from the first reactor at the same rate is fed to the 2nd reactor of the cascade, where the copolymerization process proceeds at 75 ^° C until the conversion of monomers to 90%, after which the latex is continuously fed to the 3rd reactor of the cascade, where it is copolymerized at 81 ^° C before the conversion of 98%. The speed of rotation of the mixer in the first reactor is 25 rpm, in the second reactor - 13 rpm, in the third reactor - 13 rpm.

After the copolymerization is completed, the obtained latex of the ABS copolymer (33%) from the 3rd reactor of the cascade enters the evaporator, where the residual monomers (ST and AN) are distilled off with water vapor. Pre-in the feed pipe mix ABS latex with an aqueous solution of antifoam - KE-10-12. In the evaporator maintain a temperature of 60 ± 3 ^o C at a residual pressure of 150-200 mm RT.article

After distillation of the residual monomers, the latex of the ABS copolymer is continuously fed to coagulation. Coagulation is carried out in an apparatus with a capacity of 2.3 m ³ equipped with a stirrer, with a stirring speed of 850 rpm. In a coagulator, at the same time, in separate streams, continuously enter:
- latex ABS copolymer with a speed of 6480 kg / h;
- an aqueous solution of coagulant containing 80 kg of aluminum sulfate, at a speed of 6500 kg / h;
- 16% aqueous emulsion of the stabilizer - Ionol at a speed of 75 kg / h;
- 10% aqueous hydrogen peroxide solution at a rate of 40.6 kg / h.

При использовании перекиси водорода в виде 10%-ного раствора ее количество составляет 40,6 кг.The amount of hydrogen peroxide that must be supplied at the stage of coagulation is determined by the formula

When using hydrogen peroxide in the form of a 10% solution, its amount is 40.6 kg.

The temperature of the flow of reagents supplied to the coagulation is:
- latex ABS copolymer 60 ^o C;
- an aqueous solution of aluminum sulfate 60 ^o C;
- emulsion stabilizer Ionol 80 ^o C;
- a solution of hydrogen peroxide 20 ^o C.

The ABS copolymer powder released after coagulation is squeezed out on a vacuum filter and washed with water. The temperature of the wash water is 60 ^o C. Then the powder is dried at 90-115 ^o C and sent to granulation.

 The synthesis and coagulation parameters of the ABS copolymers of example 1 and all of the following examples are shown in table 1; characteristics and properties of ABS copolymers are shown in table 2.

 Examples 2 and 3.

что составляет 37,0 кг 10%-ного водного раствора перекиси водорода (пример 2), и

что составляет 42,0 кг 10%-ного водного раствора перекиси водорода (пример 3).The process is carried out analogously to example 1, but the concentration of TDDM in the initial reaction mixture is 0.52 wt.% (Example 2) and 0.59 wt.% (Example 3), respectively. At the coagulation stage, hydrogen peroxide is introduced in an amount

which is 37.0 kg of a 10% aqueous solution of hydrogen peroxide (example 2), and

which is 42.0 kg of a 10% aqueous solution of hydrogen peroxide (example 3).

Examples 4 and 5 (control)
The process is carried out analogously to example 1, but an aqueous solution of hydrogen peroxide is introduced into the latex of the ABS copolymer after distillation of the residual monomers before the coagulation step (example 4) and in the washing step, after the coagulation step (example 5).

Example 6 (control prototype)
The process is carried out analogously to example 1, but the hydrogen peroxide solution is not introduced.

Example 7
The process is carried out analogously to example 1, but using latex butadiene rubber with a solids content of 44% and fed to the mixer with separate streams:
- 1498.13 kg / h of a mixture of monomers (hydrocarbon phase), consisting of 560 kg (27.9 wt.%) AN and 929.3 kg (46.3 wt.%) ST and containing 8.83 kg TDDM (0 , 44 wt.%);
- 1216.8 kg / h of aqueous latex of butadiene rubber (25.8 wt.%) With a dry matter content of 44%, containing 40 kg (2 wt.%) Of potassium soap disproportionate rosin;
- 3460 kg / h of demineralized water;
- 38.0 kg / h of a 3% aqueous initiator solution containing 1.14 kg of potassium persulfate (0.055 wt.%).

 The ratio of hydrocarbon and aqueous phases is 1: 2.

From the mixer, the finished reaction mixture enters the 1st reactor of the cascade of reactors at a speed of 6500 kg / h. The polymerization temperature in the first reactor is 68 ^o C, in the second - 78 ^o C and in the third - 85 ^o C. For coagulation simultaneously in separate streams arrive:
- latex ABS copolymer with a speed of 6370 kg / h;
- an aqueous solution of coagulant containing 75 kg of aluminum sulfate, at a speed of 6500 kg / h;
- 16% aqueous emulsion of the stabilizer - Ionol at a speed of 82 kg / h;
- 15% aqueous hydrogen peroxide solution at a rate of 20.5 kg / h.

При использовании перекиси водорода в виде 15%-ного водного раствора ее количество составляет 20,5 кг.The amount of hydrogen peroxide, which must be submitted at the stage of coagulation, is determined by the formula

When using hydrogen peroxide in the form of a 15% aqueous solution, its amount is 20.5 kg.

 Further, the process is carried out analogously to example 1.

Example 8 (control prototype)
The process is carried out analogously to example 7, but a solution of hydrogen peroxide is not introduced.

Example 9
Obtaining a high rubber ABS copolymer using styrene-butadiene rubber latex.

 The process is carried out analogously to example 1, but in the following mode.

Separate flows continuously fed into the mixer:
- 999.74 kg / h of a mixture of monomers (hydrocarbon phase), consisting of 297.3 kg (13.8 wt.%) AN and 693.4 kg (32.2 wt.%) ST and containing 7.54 kg ( 0.35 wt.%) TDDM and 1.5 kg (0.07 wt.%) Irganox 1520;
- 2812.84 kg / h of aqueous latex of styrene-butadiene rubber (54 wt.%) With a dry matter content of 42%, containing 43.08 kg (2 wt.%) Of potassium soap disproportionate rosin;
- 2601.2 kg / h of demineralized water;
- 106.6 kg / h of a 3% aqueous initiator solution containing 3.2 kg of potassium persulfate (0.15 wt.%).

 The ratio of hydrocarbon and aqueous phases is 1: 2.

что составляет 18,1 кг 10%-ного водного раствора перекиси водорода.The amount of hydrogen peroxide supplied in the coagulation stage is determined by the formula

which is 18.1 kg of a 10% aqueous solution of hydrogen peroxide.

 The resulting ABS copolymer containing 54.4 wt.% Rubber, in an amount of 30 wt. including mixed in a mixer "Banbury" with 70 wt. including copolymer SAN obtained by emulsion polymerization, as well as with the addition of a plasticizer - calcium stearate and stabilizer (Irganox 245). Standard samples are cast from the resulting mixture and the properties are determined on them: Izod impact strength, tensile yield strength, elongation at break.

 Properties of the obtained compositions are shown in table 2.

Example 10 (control)
The process is carried out analogously to example 9, but an aqueous solution of hydrogen peroxide is introduced into the latex of the ABS copolymer after distillation of the residual monomers before the coagulation step.

Example 11 (control)
The process is carried out analogously to example 9, but an aqueous solution of hydrogen peroxide is introduced at the washing stage after the coagulation stage.

Example 12 (control, prototype)
The process is carried out analogously to example 9, but a solution of hydrogen peroxide is not introduced.

Example 13
Obtaining a high rubber ABS copolymer using butadiene rubber latex.

 The process is carried out analogously to example 9, but instead of aqueous latex of styrene-butadiene rubber take 2937 kg / h butadiene rubber latex (60 wt.%) with a dry matter content of 44 wt.% and 2560 kg / h of demineralized water.

 The amount of hydrogen peroxide introduced in the coagulation stage, analogously to example 9.

 The obtained ABS copolymer with a rubber content of 60.5 wt.% Is mixed with the SAN copolymer as in Example 9.

Example 14 (control prototype)
The process is carried out analogously to example 13, but a solution of hydrogen peroxide is not introduced.

Example 15
Obtaining an ABS copolymer with a high rubber content by a batch method.

 12.5 kg of demineralized water and 13.5 kg of aqueous latex of butadiene rubber with a dry matter content of 45% (60 wt.%) Containing 0.2 kg of potassium disproportionated rosin are loaded into a 50 L reactor equipped with a jacket and impeller stirrer. .

The reactor is purged with nitrogen, after which 2.8 kg (28 wt.%) CT and 1.2 kg (12 wt.%) AN and 0.024 kg (0.24 wt.%) TDDM are loaded into it. The stirrer is turned on and the contents of the reactor are kept at 50 ^° C. and stirring for 2 hours to create a stable emulsion of components of the reaction mixture. Then the temperature of the reaction mixture was raised to 65 ^° C., 0.024 kg of a polymerization initiator, potassium persulfate, was introduced and polymerization was carried out for 4 hours at 65 ^° C. and 6 hours at 75 ^° C. under a nitrogen blanket. At the end of the polymerization, the unreacted monomers are distilled off, and the obtained 33% latex of the ABS copolymer is fed to coagulation.

The coagulator is continuously fed in separate streams:
- 28 kg of latex ABS copolymer;
- 70 kg of an aqueous solution of a coagulant containing 1 kg of aluminum sulfate;
- 0.5 kg of stabilizer emulsion - Ionol;
- 0.063 kg of an 8% aqueous solution of hydrogen peroxide.

что составляет 0,063 кг 8%-ного водного раствора. Далее процесс ведут аналогично примеру 13.The amount of hydrogen peroxide, which must be supplied at the stage of coagulation, is determined by the formula

which is 0.063 kg of an 8% aqueous solution. Next, the process is carried out analogously to example 13.

Example 16
The process is carried out analogously to example 15, but the content of butadiene rubber is 70 wt.% And 11.5 kg of demineralized water, 15.5 kg of latex of butadiene rubber with a dry matter content of 45 wt. % containing 0.2 kg of potassium soap disproportionate rosin, 2.1 kg (21 wt.%) CT, 0.9 kg (9 wt.%) AN and 0.024 kg (0.24 wt.%) TDDM.

Example 17 (control prototype)
The process is carried out analogously to example 15, but a solution of hydrogen peroxide is not introduced.

Example 18
The process is carried out analogously to example 15, but octyl mercaptan is used as a MM regulator.

Example 19 (control prototype)
The process is carried out analogously to example 18, but a solution of hydrogen peroxide is not introduced.

As can be seen from the data in table 2, the claimed method provides for the preparation of grafted ABS copolymers that have virtually no unpleasant odor at processing temperatures. So the odor intensity of the ABS copolymer obtained by the present method is at 220 ^o C 0.5-1.0 points, while similar copolymers obtained by the prototype method have an odor intensity of 3.5-5 points. The introduction of ABS copolymers simultaneously with the coagulant at the stage of coagulation of the latex with a separate stream of an aqueous solution of hydrogen peroxide in the amounts determined by the above formula can drastically reduce the unpleasant odor of the copolymers, which they usually have due to the presence of mercaptans and food additions, without affecting the physical mechanical properties and processability of the resulting copolymer. Good compatibility of ABS copolymers with other polymers is also maintained.

Claims (4)

1. The method of obtaining acrylonitrile butadiene styrene copolymers containing up to 70 wt. % rubber, including the graft copolymerization of styrene and acrylonitrile in the absence of oxygen in an aqueous emulsion medium in the presence of a preformed butadiene rubber latex under the influence of a radical type initiator in the presence of a molecular weight regulator - dodecyl mercaptan or octyl mercaptan, distillation of unreacted latent acrylonomethyl aminomeric monomers an aqueous solution of a coagulant, separating the copolymer from the aqueous medium, washing and drying it, excellent In that, during coagulation of the latex of the acrylonitrile butadiene styrene copolymer, simultaneous introduction into the latex of the copolymer is carried out by separate streams of an aqueous solution of a coagulant and an aqueous solution of hydrogen peroxide, while the amount of hydrogen peroxide to be introduced during coagulation of the latex of the copolymer is determined by the formula

where GH ₂ O ₂ - the amount of hydrogen peroxide, which must be entered during coagulation of latex, kg;
K is a coefficient taking into account the rubber content in the copolymer and equal to 0.11 for copolymers with a rubber content of up to 30 wt.% And 0.08 for copolymers with a rubber content of 30 - 70 wt.%;
[M] is the amount of molecular weight regulator introduced — dodecyl mercaptan or octyl mercaptan,% of the mass of grafted monomers and rubber (based on the dry residue of latex);
G _l - the amount of latex copolymer sent for coagulation, kg 2. The method according to claim 1, characterized in that the grafted copolymerization of styrene and acrylonitrile in an aqueous emulsion medium is carried out with a stepwise rise in temperature from 60 - 68 ^o C to 75 - 85 ^o C.  3. The method according to claim 1 or 2, characterized in that the hydrogen peroxide is introduced in the form of an 8-15% aqueous solution.  4. The method according to claims 1, 2 or 3, characterized in that when coagulating the latex acrylonitrile butadiene styrene copolymer simultaneously with aqueous solutions of the coagulant and hydrogen peroxide, an aqueous emulsion of heat and / or light stabilizer is introduced in a separate stream.

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