MXPA06005954A - Antioxidant compositions of octylated diphenylamines and method of their preparation - Google Patents

Abstract

Antioxidant compositions of octylated diphenylamines, containing 65 to 98%by weight of dioctyldiphenylamine, up to 29%by weight of monooctyldiphenylamine, up to 5%by weight of octylbutyldiphenylamine, up to 1.5%by weight of trioctyldiphenylamine and up to 1%by weight of diphenylamine, are prepared by alkylation of diphenylamine by diisobutylene in the presence of an acidic catalyst. They can be used as efficient stabilizers of polymeric materials, lubricants and oils, either alone or as a component of anti-degradation systems and substances based on them.

Description

ANTIOXIDANT COMPOSITIONS OF DIPHENYLAMINES OXIDATED AND METHOD OF ITS PREPARATION TECHNICAL FIELD The invention relates to antioxidant compositions based on octylated diphenylamines, as well as to a method of preparing them. The compositions in question can be used as effective stabilizers for polymeric materials, lubricants and oils. They are used as additives for stabilization of organic products that undergo oxidative, thermal or light-induced degradation.

PREVIOUS TECHNIQUE The majority of industrially produced polymeric materials, oils and lubricants require the presence of intentionally added substances to ensure the stability required during their processing, storage and use in finished articles. These substances retard or inhibit undesirable oxidation phenomena in a given substrate, so as to prevent complete deterioration by the influence of oxygen, increased temperature, UV radiation and mechanical stress. The above requirements are met by substances showing an anti-oxidant effect. The most known and most frequently used group of these is the group of amine-degrading antifoulants, for example,? / - phenyl-1-naphthylamine,? / - (4-ér-octylphenyl) -naphthylamine,? / - (1 , 3-d-methylbutyl) -? / '- f in i-lp-phenylene amine, / V-isopropyl-β-phenyl-p-phenylenediamine (CS AO 261 085 and CS AO 226 248). They can be easily modified and it is possible to obtain substances having properties required for a broad spectrum of various materials, as well as processing and operating conditions of use. The alkylated diphenylamines are effective in oils, lubricants for turbine machines, aircraft and anywhere, where there is high operating temperature, and in combination with other additives ensure high thermal and anti-oxidant protection (CS AO 226 248, US 3 414 618). They are usually slightly colored, resistant against becoming yellow in comparison with unsubstituted diphenylamine, which in addition to the anti-oxidant properties tends to turn yellow in rubber mixtures. Alkylated diphenylamines are frequently prepared by Friedel-Crafts reaction typical of alkylation of aromatic amines by olefins. Industrial alkylations use the typical Friedel-Crafts AICI3 catalyst. Also other catalysts, such as for example H2SO4, anhydrous HF, H3PO4 in vehicles, various aluminosilicates, zeolites, stacked clays, are suitable. Advantages of AICI3 are its high catalytic activity and insolubility in organic substances, the disadvantages are its high sensitivity to the presence of water, corrosive properties, demanding way to remove it from the reaction mixture, as well as a large amount of wastewater is originates, presence of chlorine in the products and presence of undesirable byproducts, including those that are rented in nitrogen.

AICI3 belongs to efficient alkylation catalysts for diphenylamine which, in addition to the fact that it accelerates the alkylation to the 4,4 'positions of diphenylamine, also catalyzes separation reactions stipulating that the reactant is diisobutylene. Tert-butyl derivatives arise and in the subsequent reactions considerable amounts of trioctyldiphenylamine, thus causing reduction in the amount of 4,4'-dioctyldiphenylamine desirable. These weak points are solved partially when using bentonite-based catalysts (US 6 315 925). The use of some aluminosilicates without prior activation is described in SU 443 026. The disadvantages of this process are low catalyst activity and its variable quality, even if from a source. Natural aluminosilicates are also activated by an acid to increase their catalytic efficiency (US 2 943 1 12, US 4 163 757, US 4 824 601). The disadvantages of using bentonite-based catalysts according to US Pat. U U. above are low concentration of 4,4'-dioctyldiphenylamine and high content of unreacted diphenylamine up to 5%. The alkylation of aromatic amines is carried out by alkylating agents which are predominantly constituted by olefins, especially isobutene, diisobutylene, nonene, styrene, alphamethylstyrene (US 2 943 1 12, US 3 714 258, SK PP 743-98 published); the alkene can also be pentene-1, hexene-1, heptene-1, octane-1, noneno-1 or mixtures thereof. The alkylation of aromatic amines by, for example, nonene is described in SK PP 743-98, where four to ten times the molar excess of nonene, based on diphenylamine, is used for the preparation of the resulting product, and the alkylation is carried out at a temperature of 150 to 220 ° C. The disadvantages of this method are the relatively high temperature and high excess of nonene that must be subsequently removed from the reaction mixture for the purpose of regeneration, thus together with the excess reaction temperature increasing the production costs. In US 5 672 752, the use of a catalyst based on bentonite which is preferred in the monoalkylation process on dialkylation at specific conditions, similar temperature and molar ratio of diphenylamine to diisobutylene (DFA: DIB) is described. A disadvantage of this method is the fact that it does not provide a product having the required amount of 4,4'-dioctyldiphenylamine. Alkylation of DFA by diisobutylene using activated aluminosilicate is described in US 5 520 848. The synthesis of 4,4'-dioctyldiphenylamine from DFA and DI B with its content, less than 25% in the reaction mixture using activated clay, as the Fulcat 22B catalyst is described in US 4 824 601. However, the reaction product still contains 10% unreacted DFA. Furthermore, a disadvantage of all the above processes is, as already mentioned, relatively low concentration of 4,4'-dioctyldiphenylamine-less than 30%. The object of the present invention is to present compositions of octylated diphenylamines with the disadvantages in question eliminated.

DESCRIPTION OF THE INVENTION The above problem is solved by antioxidant compositions of octylated diphenylamines according to the present invention, the nature of which is that the composition contains 65 to 98% by weight of dioctyldiphenylamine, at most 29% by weight of monooctyldiphenylamine, maximum 5% by weight of octyl butyldiphenylamine, maximum 1.5% by weight of trioctyldiphenylamine and maximum 1% by weight of diphenylamine, while the remainder consists of products of separation of diisobutylene with diphenylamine. Also to the nature of the invention is the composition, containing 83 to 89% by weight of dioctyldiphenylamine, 7 to 13% by weight of monooctyldiphenylamine, 0.8 to 4% by weight of octylbutyldiphenylamine, 0.1 to 1.5% by weight of trioctyldiphenylamine and 0.1 to 1% by weight of diphenylamine, as well as the composition, containing 92 to 94.5% by weight of dioctyldiphenylamine, 2.5 to 4.5% by weight of monooctyldiphenylamine, 1.4 to 2% by weight of octylbutyldiphenylamine, 0.3 to 1% by weight weight of trioctyldiphenylamine and maximum of 0.5% by weight of diphenylamine, and the composition, containing 96 to 98% by weight of dioctyldiphenylamine, 0.6 to 2.1% by weight of monooctyldiphenylamine, 0.8 to 1.1% by weight of octylbutyldiphenylamine, 0.1 to 0.5 % by weight of trioctyldiphenylamine and maximum of 0.3% by weight of diphenylamine. It has been found to be preferred if the octylated diphenylamine composition contains at least 83% by weight of dioctyldiphenylamine, up to 10% by weight of monooctyldiphenylamine, up to 4% by weight of octylbutyldiphenylamine, up to 1.5% by weight of trioctyldiphenylamine and up to 1% by weight of diphenylamine.

It is also preferred if the composition contains at least 92% by weight of dioctyldiphenylamine, up to 5% by weight of monooctyldiphenylamine, up to 2% by weight of octyl butyldiphenylamine, up to 1% by weight of trioctyldiphenylamine and up to 0.5% by weight of diphenylamine. Even more preferred are the antioxidant compositions, containing at least 95% by weight of dioctyldiphenylamine, up to 2% by weight of monooctyldiphenylamine, up to 1% by weight of octylbutyldiphenylamine, up to 0.5% by weight of trioctyldiphenylamine and maximum of 0.3% by weight of diphenylamine. . An advantage of antioxidant compositions according to the present invention is the fact that they have highly reduced content of trioctyldiphenylamine and very low content of diphenylamine (trioctyldiphenylamine and diphenylamine reduce the antioxidant efficiency of antioxidant compositions and, in addition, diphenylamine deteriorates the undesired properties, for example, toxicity, to the products). In this way, the increased purity of the composition manifests itself by better protective action in rubber mixtures. Also the fact that the compositions in question occur in solid state can be considered as an advantage, this being especially preferred from the point of view of transport and storage ability. The invention also relates to a method of preparing an antioxidant composition of octylated diphenylamines by catalytic alkylation of diphenylamine by alkene in the presence of an alkylation catalyst, the nature of which is that the catalytic alkylation of diphenylamine is carried out by diisobutylene with an excess of diisobutylene with respect to diphenylamine, in the presence of acid clay as a catalyst in an amount of 5 to 30% by weight, as it relates to diphenylamine, at a temperature of 140 to 160 ° C. The water contained in the catalyst is removed, subsequently diphenylamine is allowed to complete the reaction with diisobutylene and after the reaction has finished, the reaction mixture is separated from the catalyst, and unreacted diisobutylene is removed from the reaction product containing octylated diphenylamines. . The catalytic reaction of alkylation of diphenylamine by diisobutylene is carried out at an atmospheric pressure or overpressure of up to 0.6 MPa, at a catalyst concentration of 5 to 30% by weight. The suitable catalysts are acid clays activated on the basis of a layered silicate, for example, montmorillonite, activated by mineral acids, such as sulfuric acid or hydrochloric acid, in which the moisture content is preferably less than 10%, for example, commercially available types with the designations Fulcat 22B, acid clays K5, K1 0 , Jeltar 100, Jeltar 300 or Nobelin FF and Nobelin GF. An advantage of the method for preparing anti-oxidant compositions of octylated diphenylamines according to the present invention consists in the need for a lower molar excess of the alkylating agent or its mixtures, compared to the production process of higher alkene mixtures (SK PP 743-98), despite the fact that diisobutylene has a branched chain and can undergo separation, this being allowed for milder reaction conditions. The milder reaction conditions and the need to remove a smaller amount of unreacted diisobutylene allow both to obtain preferred antioxidant compositions from the point of view of purity and content of components in the 4 and 4,4 'positions of diphenylamine, and to make the cheapest technology. A further advantage is the fact that the catalyst can be reused after the separation of the reaction medium or without its separation in the next batch with addition or without the addition of a new catalyst. The catalyst used in this production method can be removed from the reaction mixture by filtration, centrifugation or decantation, and can be used again in the catalytic reaction of alkylation of diphenylamine by diisobutylene. The catalyst used is reused in a second to ninth batch, and the aggregate amount of the new catalyst ranges from 0.01 wt% to 70 wt%, as it relates to the catalyst load in the first alkylation batch. An advantage of the method according to the present invention is also the fact that the reaction is carried out without addition of organic solvents. The desired chemical composition of the resulting mixture is obtained after alkylation by low boiling-processing components of distillation at atmospheric or reduced pressure, rectification, extraction and / or crystallization using a solvent or extraction agent. Methanol, ethanol, isopropanol, cyclohexanol, cyclohexane and / or diisobutylene are suitable as solvents. The products of the described production method are antioxidant compositions with a high degree of conversion of the initial diphenylamine, which are easily separable from the catalyst used thanks to the catalytic system used and reaction conditions also with very low content of trialkylated diphenylamines. In addition, the bleaching properties of the acid clays used as catalysts ensure markedly lighter coloration for the compositions compared to compositions prepared using AICI3. The commercial catalysts as efficient solid catalysts are Fuller, Fulcat 22B, Fulmont 237 clays, clays based on montmorillonite KSF, K10, Süd Chemie K5 catalyst and activated acid clays based on bentonite, but also natural acid clay Zikijevská opoka. Its advantage, compared to AICI3, consists in the possibility of simple separation of the reaction mixture by filtration and in use of its bleaching properties, whereby the slightly lighter product is obtained than with AICI3. The production of the compositions can be carried out by batch, continuous or possibly semi-continuous method. The examples below also illustrate, but do not limit, the subject of the invention.

EXAMPLES OF MODALITIES OF THE INVENTION Example 1 1 00 g of diphenylamine fusion (DFA) are charged to a glass reactor, equipped with a stirrer, a cooler with an azeotropic junction, separating funnel and a thermometer. After 30 g of a bentonite-based catalyst Nobelin FF (30% by weight, as it relates to DFA) are added. After mixing the catalyst, the mixture is heated to a temperature of 160 ° C and for 5 hours 397 g of diisobutylene are added uniformly. During the first hour from the start of the addition of diisobutylene, the water originating from the catalyst is distilled azeotropically. After all of the diisobutylene is used, the reaction mixture is allowed to react for another 14 hours. After the reaction is complete, the catalyst is allowed to settle and the mixture is decanted. After the diisobutylene is distilled, a composition is obtained, which contains 70.2 wt% of dioctyldiphenylamine, 25.8 wt% of monooctyldiphenylamine, 2.8 wt% of octyl butyldiphenylamine, 0.5 wt% of trioctyldiphenylamine, 0.4 wt% of diphenylamine . The remainder of 100% by weight consisted of diisobutylene separation products (DIB). Example 2 - Comparative In the apparatus of Example 1, 0.2 mol of AICI3 is added to 1 mol of diphenylamine fusion. The mixture is heated to 1 15 ° C. All the diisobutylene is fed at this temperature and after having removed the catalyst and distilled the unreacted diisobutylene, after 6 hours, the reaction mixture was obtained, which contained 66.2% by weight of diooctyldiphenylamine, 25.4% by weight of monooctyldiphenylamine , 0.2% by weight of octyl butyldiphenylamine, 1.79% by weight of trioctyldiphenylamine and 3.3% by weight of diphenylamine. The rest consisted of DI B separation products as well.

Example 3 - Comparative In the apparatus of Example 1 with the melting amount of diphenylamine as in Example 2, 0.25 mol of AICI3 are added. The mixture is heated to 1 1 5 ° C. All diisobutylene is fed at this temperature. After removing the catalyst and distilling off the unreacted diisobutylene and after the reaction is complete, the reaction mixture is obtained, which contains 67.3% by weight of dioctyldiphenylamine, 23.1% by weight of monooctyldipheniamine, 0.3% by weight of octylbutyldipheniamine, 2.2% by weight of trioctyldiphenylamine and 2.7% by weight of diphenylamine. Example 4 In the apparatus of Example 1 with the stock of prime stock as in Example 1, the diphenylamine melt is loaded, and to the catalyst used of Example 1, 20 wt.% Of new Nobelin FF catalyst are added, as referred to the amount of catalyst in the first batch. The mixture is heated to a temperature of 140 ° C in the course of 5 hours diisobutylene is added. After 21 hours the reaction is stopped and the mixture is processed as in Example 1. The composition obtained contained 65.8% by weight of dioctyldiphenylamine, 29.1% by weight of monooctyldiphenylamine, 2.0% by weight of octylbutyldiphenylamine, 0.3% by weight of trioctyldiphenylamine and 0.4% by weight of diphenylamine. The catalyst was used in additional experiments 9 times in total after loading new starting materials and adding each time 30% by weight of new catalyst, where Nobelin FF is replaced by Nobelin GF after the fourth addition of 30% of new catalyst to the catalyst used. After 21 hours of reaction the resulting composition contained 70.86% by weight of dioctyldiphenylamine, 21.5% by weight of monooctyldiphenylamine, 2.2% by weight of octylbutyldiphenylamine, 0.5% by weight of trioctyldiphenylamine and 0.2% by weight of diphenylamine. After the ninth repeated use of the catalyst and the addition of new catalyst, the composition obtained contained 66.0% by weight of dioctyldiphenylamine, 28.0% by weight of monooctyldiphenylamine, 2.0% by weight of octylbutyldiphenylamine, 0.33% by weight of trioctyldiphenylamine and 0.2% by weight of diphenylamine. Example 5 In the apparatus of Example 1 with the diphenylamine melting amount as in Example 1, 15 g of the Fulcat 22 catalyst (15% by weight, as it relates to DFA) are added. After mixing the catalyst the mixture is heated to a temperature of 160 ° C and in the course of 10 hours 397 g of diisobutylene are added uniformly. During the first hour from the start of the addition of diisobutylene, the water originating from the catalyst is distilled azeotropically. After 18 hours the reaction is stopped and the mixture is processed as in Example 1. The reaction mixture obtained contained 68.5% by weight of dioctyldiphenylamine, 24.9% by weight of monooctyldiphenylamine, 4.9% by weight of octylbutyldiphenylamine, 1.4% by weight of trioctyldiphenylamine and 0.3% by weight of diphenylamine. Example 6 In the apparatus of Example 1, the diphenylamine melt in an amount as in Example 1 is charged and 20 g of the Jeltar 300 catalyst (20% by weight, as it relates to DFA) are added. After mixing the catalyst the mixture is heated to a temperature of 140 ° C and in the course of 5 hours diisobutylene is added uniformly. During the first hour the water originating from the catalyst is distilled azeotropically and after 28 hours the reaction is stopped and the mixture is processed as in Example 1. The reaction mixture obtained contained 67.9% by weight of dioctyldiphenylamine, 28.7% by weight of monooctyldiphenylamine, 1.3% by weight of octylbutyldiphenylamine, 0.2% by weight of trioctyldiphenylamine and 0.4% by weight of diphenylamine. Example 7 In the apparatus of Example 1 with the amount of diphenylamine and diisobutylene as in Example 1 the diphenylamine melt is charged and 20 g of the K5 Süd Chemie catalyst (20% by weight, as referred to DFA) are added. After mixing the catalyst, the mixture is heated to a temperature of 140 ° C and for 5 hours diisobutylene is added evenly. During the first hour the water originating from the catalyst is distilled azeotropically, after 21 hours, the reaction is stopped and the mixture is processed as in Example 1. The composition obtained contained 69.8% by weight of dioctyldiphenylamine, 25.0% by weight of monooctyldiphenylamine, 1.0% by weight of octylbutyldiphenylamine, 0.3% by weight of trioctyldiphenylamine and 0.2% by weight of diphenylamine.

Example 8 From the reaction mixture of Example 1, the catalyst is removed by decanting and unreacted diisobutylene is distilled from the liquid phase at a temperature of 1 03 to 107 ° C and a pressure of 1 01 kPa (alternatively at a temperature of 68 ° C and a pressure of 20 kPa). The obtained mixture is subsequently adjusted to the desired chemical composition by rectification of light fractions in a column packed at a temperature of 148 to 153 ° C and a pressure of 8 to 1 0 Pa. The required composition, formed by the residue of distillation is obtained, which contains 84.3% by weight of dioctyldiphenylamine, 9.9% by weight of monooctyldiphenylamine, 1.6% by weight of octylbutyldiphenylamine, 0.5% by weight of trioctyldiphenylamine and 0.01% by weight of diphenylamine. Example 9 The antioxidant composition prepared according to Example 1 is adjusted to the chemical composition required by crystallization of the reaction mixture according to Examples 1 to 8 in methanol, ethanol, isopropanol, cyclohexanol, cyclohexane and / or diisobutylene so that 100 ml of solvent are added thereto with stirring at a temperature of 50 ° C and after cooling to 10 ° C the mixture crystallizes. The crystalline product is filtered and dried. The chemical composition of the crystallized compositions of various solvents are given in Table I.

Table I: Chemical composition of antioxidant compositions after crystallization Example 10 100 ml of methanol are added to 60 g of the reaction product of Example 4. The suspension obtained is heated to a temperature of 60 ° C and filtered at 10 ° C. After rinsing the filter cake with methanol, a distillation residue having the following composition is obtained: 93.8% by weight of dioctyldiphenylamine, 3.8% by weight of monooctyldiphenylamine, 1.8% by weight of octylbutyldiphenylamine, 0.3% by weight of trioctyldiphenylamine and 0.0% by weight of diphenylamine. Example 1 1200 g of the reaction mixture of Example 6 are charged to the distillation apparatus, the mixture is heated and at a temperature of 240 ° C and atmospheric pressure dimer of diisobutylene is distilled, and at a temperature of 175 ° C and the pressure of 20 kPa of diphenylamine with one part of monooctyldiphenylamine is distilled in such a way that the distillation residue is obtained having the following composition: 92.6% by weight of dioctyldiphenylamine, 2.5% by weight of monooctyldiphenylamine, 1.8% by weight of octyl butyldiphenylamine, 0.3% by weight of trioctyldiphenylamine and 0.0% by weight of diphenylamine. After cooling to a temperature of 150 ° C and reducing the pressure to 10 kPa another 1 0 g of mixture of octylbutyldiphenylamine and monooctyldiphenylamine are distilled. After adding the equimolar mixture of ethanol, isopropanol, cyclohexanol, cyclohexane, diisobutylene and methanol in an amount of 1.0 g, the mixture is tempered at 60 ° C, cooled to 20 ° C and filtered. The filter cake obtained had the following composition: 97.5% by weight of dioctyldiphenylamine, 0.9% by weight of monooctyldiphenylamine, 0.9% by weight of octylbutyldiphenylamine, 0.2% by weight of trioctyldiphenylamine, 0.01% by weight of diphenylamine. Example 12 The antioxidant compositions of octylated diphenylamines of Examples 2, 8 and 11 are used in a concentration of 2 parts by weight / 100 parts of rubber to stabilize the natural rubber. These antioxidant compositions under the designation DODFA 1, DODFA 2, DODFA 3 and other antioxidants - Dusantox 86 and TMQ (Flectol) are mixed with a NR base filled with natural gas carbon black (SMR5, Vulkan 3, ZnO, stearin). The course of thermooxidating maturation of vulcanizates prepared and stabilized in this way is monitored based on the change of basic psychomechanical properties of vulcanized sample pieces at a temperature of 145 ° C using the method according to ISO 3417 for 5 to 12 days in air stream at a temperature of 70 ° C. The results are given in Table I I.

Table II: Psychomechanical properties of vulcanized before and after thermooxidizing maturation Antioxidants used: 1. DODFA 1 -Composition according to Example 2 2. DODFA 2 -Composition according to Example 8 3. DODFA 3 -Composition according to Example 11 4. TMQ -2,2,4-trimethyl-1,2-dihydroquinoline polymerized 5. Dusantox 86 -4- (1,1-dimethylbenzyl) -diphenylamine and 4,4 '- (1,1- di meti I ben cil) -difen ilamine Table ll l: Strength of vulcanizates against dynamic tension before and after of thermooxidating maturation (3 days at 100 ° C) Legend: kc = kilocycles From the results given, it is obvious the antioxidant effect of the octylated diphenylamine composition that increases at longer exposure time. Industrial Application The mixtures of octylated diphenylamines can be used in the chemical, rubber and petroleum industries to stabilize polymeric materials, lubricants, oils and fuels.

Claims (15)

1. CLAIMS 1. Method of preparing the antioxidant composition in the diphenylamine base by catalytic alkylation of diphenylamine by an excess of diisobutylene in the presence of an alkylation catalyst, characterized in that the catalytic alkylation of diphenylamine is carried out in excess of three times as much diisobutylene with with respect to diphenylamine in the presence of acid clay as a catalyst in an amount of 5 to 30% by weight, as it relates to diphenylamine, at a temperature of 140 to 160 ° C, while the water contained in the catalyst is removed and subsequently diphenylamine is allowed to complete the reaction with diisobutylene and then the reaction is terminated, the reaction mixture is separated from the catalyst, unreacted diisobutylene is removed therefrom and the reaction product is obtained.
2. 2. Method of preparation according to claim 1, characterized in that the catalytic alkylation of diphenylamine is carried out at atmospheric pressure.
3. 3. Method of preparation according to claim 1, characterized in that the catalytic alkylation of diphenylamine is carried out at an overpressure of up to 0.6 MPa.
4. 4. Method of preparation according to claim 1, characterized in that the catalytic alkylation of diphenylamine is carried out in the course of 1 8 to 28 hours. Method of preparation according to claim 1, characterized in that the catalytic alkylation of diphenylamine is carried out in the presence of a catalyst selected from the group including Nobelin FF, Nobelin GF, Jeltar 1 00, Jeltar 300, catalyst K5, K10 Süd Chemie, Fulcat 22B. Method of preparation according to claim 1, characterized in that the unreacted diisobutylene and possibly the low-boiling components present are removed by azeotropic distillation. Method of preparation according to claim 1, characterized in that the catalyst is reused after the separation of the reaction medium or without its separation in an additional batch with or without the addition of a new catalyst, wherein the catalyst is used in the second ninth batch and the amount of new catalyst added is from 0.01 to 70% by weight, as it relates to the catalyst charge in the first batch of alkylation. Method of preparation according to claim 1, characterized in that the reaction product is further processed by reaction in a packed column at a temperature of 148 to 153 ° C and a pressure of 8 to 10 Pa. 9. Method of preparation according to claim 1, characterized in that the reaction product is allowed to crystallize from a solvent selected from the group including ethanol, isopropanol, cyclohexanol, cyclohexane, diisobutylene, and methanol, or from a mixture of these solvents. 10. Method of preparation according to claim 1, characterized in that the reaction product is extracted by one or more solvents chosen from the group including ethanol, isopropanol, cyclohexanol, cyclohexane, diisobutylene and methanol. eleven . Antioxidant composition in the diphenylamine base prepared by the method according to any of claims 1 to 10, characterized in that it contains 65 to 98% by weight of dioctyldiphenylamine, up to 29% by weight of monooctyldiphenylamine, up to 5% by weight of octylbutyldiphenylamine, up to 1 .5 wt.% Of trioctyldiphenylamine and up to 1 wt.% Of diphenylamine. Antioxidant composition according to claim 1, characterized in that it contains 83 to 89% by weight of dioctyldiphenylamine, 7 to 13% by weight of monooctyldiphenylamine, 0.8 to 4% by weight of octylbutyldiphenylamine, 0.1 to 1.5% by weight of trioctyldiphenylamine. and 0.1 to 1% by weight of diphenylamine. The antioxidant composition according to claim 1, characterized in that it contains 92 to 94.5% by weight of dioctyldiphenylamine, 2.5 to 4.5% by weight of monooctyldiphenylamine, 1.4 to 2% by weight of octylbutyldiphenylamine, 0.3 to 1% by weight of trioctyldiphenylamine. and up to 0.5% by weight of diphenylamine. Antioxidant composition according to claim 1, characterized in that it contains 96 to 98% by weight of dioctyldiphenylamine,

   0. 6 to 2.1% by weight of monooctyldiphenylamine, 0.8 to 1.1% by weight of octyl butyldiphenylamine, 0.1 to 0.5% by weight of trioctyldiphenylamine and up to 0.3% by weight of diphenylamine. 15. Mixture for preparation of stabilized polymeric materials, characterized in that it contains at least one antioxidant composition according to any of claims 1 to 14.