RU2296125C1 - Modifier for synthetic cis-1,4-polyisoprene and modifying composition - Google Patents

Abstract

FIELD: organic chemistry, in particular chemicals for rubber and tire industries.

SUBSTANCE: invention relates to N-substituted monoamides of moleamic acid (MMA) and compositions containing MMA and free radical initiators for addition of MMA molecules to cis-1,4-polyisoprene (PI) macromolecules. N-substituted monoamides of moleamic acid are obtained by interaction under heating of amino group-containing compounds with maleic anhydride in medium of water-free solvent (such as toluene), followed by separation of finished product precipitate from solvent. As amino group-containing compounds oligomer mixture of 2,2,4-trimethyl-1,2-dihydroquinoline (TMDHQ), obtained after the second step of industrial synthesis of Acetonanyl H, with synthesis by-products namely primary or secondary mono-, di-, and polyamines in form of 15-20 % solution in toluene are used. Reagents are used in equimolar ratio based on monomer TMDHQ molar content in dry Acetonanyl H. After reaction multifunctional MMA are obtained. Composition for cis-1,4-polyisoprene modification includes multifunctional MMA in combination with free radical initiators for modification< such as hexachloro-p-xylene or liquid silicone compound bis-triethoxysilylpropyl tetrasulfide.

EFFECT: multifunctional MMA with low melt temperature, good compatibility with cis-1,4-polyisoprene; compositions providing cohesion strength of carbon-filled rubber mixtures without rubber destruction.

2 cl, 7 tbl, 7 ex

Description

The invention relates to chemicals used in the rubber and tire industry, and specifically to compositions for the modification of cis-1,4-polyisoprene (PI), including N-substituted maleamic acid monoamides (MMK) and free radical initiators of the attachment of MMK to PI macromolecules.

Known MMC obtained by interaction with maleic anhydride (MA) in glacial acetic acid primary and secondary alkyl and arylamines, as well as simple heterocyclic compounds with amino groups included in the heterocycle, followed by separation of the precipitate of the finished product (MMC) from the solvent (US Patent 4433114, published February 21, 1984 - prototype). These MMCs in combination with sulfur or its organic compounds as free radical initiators are proposed according to the prototype as compositions for modifying synthetic cis-1,4-polyisoprene (PI) in a special technological operation preceding the generally accepted production of carbon-filled rubber compounds in order to increase cohesive strength of these mixtures to levels close to the cohesive strength of rubber mixtures of natural polyisoprene - NK.

However, the known monofunctional MMCs (with one carboxyl group) of the prototype are, as a rule, hydrophilic, polar and poorly compatible with cis-1,4-polyisoprene compounds, and bifunctional (with two carboxyl groups) are highly melting (with a melting point above 170 ° C), which does not allow to obtain a sufficient increase in the cohesive strength of rubber compounds based on modifiable PI, comparable to the cohesive strength of mixtures of NK, when temperature PI processing presses. Free-radical initiators based on sulfur-containing compounds, proposed by the prototype for use with MMC, in addition to sulfur itself, also have high melting points, which reduces the effectiveness of their action in practically used short-term processing conditions on mixing equipment. In addition, sulfur-containing initiators during high-temperature processing of PI cause strong plasticization of rubber as a result of the destructive action and increase the risk of premature vulcanization of the resulting rubber compounds. The latter is also characteristic of sulfur itself.

These shortcomings of the known modifiers and compositions based on them with initiators of the prototype for modifications of PI do not allow their industrial use by processing PI in a separate technological operation, and in the manufacturing processes of rubber compounds associated with the production of rubber products and tires, as well as in synthetic cis-1,4-polyisoprene production.

The objective of the invention is to create such a MMC, which would have a sufficiently low melting point, would be better combined with PI, and also, on the basis of it, of creating modifying compositions that include lower melting ones than the prototype ones that do not cause rubber destruction and increase the risk of premature vulcanization initiators for them, which would allow the use of these compositions for the modification of PI, while achieving higher than the prototype values of the cohesive strength of rubber compounds.

The solution of this problem is achieved by the fact that to obtain a low-melting MMC in the reaction with MA, a toluene solution of a mixture of oligomers starting from a dimer and above, a heterocyclic monomer, 2,2,4-trimethyl-1,2-dihydroquinoline (TMDHC) is used. The specified mixture in a toluene solution is obtained by condensation of acetone and aniline in the industrial synthesis of TMQ class antioxidants (oligomerized TMDHC). In Russia, the corresponding product is called Acetononil N. This mixture also includes condensation by-products - primary and secondary mono-, di- and polyamines (below - Acetononil H solution).

The fine precipitate formed during the condensation of MA with amines in the solution of Acetononil H is a mixture of polyfunctional MMCs. After separation from the solvent and drying, it melts in the range of 130-140 ° C and is well distributed in the rubber compound. At the same time, the highly soluble PI low-melting hexachlor-n-xylene (HCPC) or liquid organosilicon compound bis-triethoxysilylpropyltetrasulfide (TESPT) is used as initiators of the addition of the MMC according to the invention.

As is known, for example, from [1], antioxidants such as Acetononyl H are mixed compositions, and, in addition to the main components, oligomers of polymerized 2,2,4-trimethyl-1,2-dihydroquinoline with a degree of oligomerization from 2 to 5 and above, contain impurities - primary and secondary mono-, di- and polyamines of various structures (more than 40 different compounds). In the process of interaction with MA of primary and secondary amines, including amine fragments included in the heterocycle of TMDHH oligomers, according to the reaction described in the prototype, the anhydride cycle of MA opens, and as a result of condensation, MMK - maleamic acid monoamides are formed. A similar reaction in the case of the interaction of various TMDHH oligomers with MA results in the formation of a mixture of polyfunctional maleamic acid monoamides, derivatives of Acetonanil N oligomers (AAMA below in the description). The structure below is an example of a reaction product, AAA with maleic anhydride, in the case of the 2,2,4-trimethyl-1,2-dihydroquinoline trimer:

The same structures will be obtained from the dimer, tetramer and oligomers TMDHH with higher MM. The number of carboxyl groups in the MMC molecule based on TMDHH oligomers with a larger MM, respectively, increases, and the resulting product is a mixture of multifunctional MMCs.

The indicated differences between the proposed MMC and its compositions with the initiators according to the invention create advantages over the prototype, which are higher than the prototype values of cohesive strength of rubber mixtures from PI after its modification by high-temperature processing by known methods. This is due to the large number of functional (carboxyl) groups capable of adsorbing on the surface of carbon black particles, providing an increase in cohesive strength, and - double bonds along which the polyfunctional MMCs are initiated to attach to PI macromolecules, and also due to the significant better distribution of the proposed composition in PI. There is no danger of premature vulcanization inherent in the use of sulfur and sulfur-containing initiators of the prototype.

The dosage of the multifunctional MMC according to the present invention in compositions for modifying PI is from 0.4 to 1.0 parts by weight, per 100 parts by weight PI, in combination with the proposed initiators - from 0.02 to 0.10 wt.h.

The raw materials (Acetononil solution) required to obtain the multifunctional MMC according to the invention are much more affordable and cheaper than the primary and secondary amines used in the prototype, and the compounds proposed as initiators for the modification of PI are widely used in practical rubber technology as components of vulcanizing systems (GHPC) and as silane binding agents in rubber compounds with precipitated silicic fillers (TESPT), respectively.

The possibility of carrying out the invention is illustrated by the following examples.

Example 1

In a 500 ml 4-necked flask equipped with a stirrer, reflux condenser and thermometer, 196.4 g of an 18% solution of Acetononil N taken from an industrial reactor after the second synthesis stage are charged. The solution taken contains 0.20 moles of Acetonanil H oligomers and impurities, based on the molecular weight of the TMDHC monomer (173). 0.2 mol or 23.2 grams of maleic anhydride is added to the solution of Acetononil H. The mixture was heated to 40 ° C and kept under stirring for 5 hours. Toward the end of the exposure, a dark brown liquid is formed containing a light brown suspension. After cooling to room temperature, the reaction mixture was filtered through filter paper on a Buchner funnel. The filter cake was washed with 100 ml of toluene. A light brown cake of 100 g mass was obtained, the main filtrate was weighed 85.3 g and the washing filtrate was weighed 82.6 g. The main and washing filtrates were combined for use in the following experiments. The precipitate in the form of fine powder is dried under a fume hood to constant weight.

Dry sediment weight - 57.8 g.

The precipitate is the reaction product of maleic anhydride with primary and secondary amines contained in a solution of Acetononil H - AAA. Melting point - 140 ° C. Product yield 90-99%.

Example 2

In the reactor according to example 1, 250.6 g of a 15% solution of Acetononil N in toluene are poured, which corresponds to 0.217 mol of a substance in terms of TMDHC monomer. With stirring, an equimolar amount (25.3 g) of MA is added to the solution, and the temperature of the mixture is raised to 70 ° C. The mixture is kept under stirring, not allowing the temperature to rise above 70 ° C, for 3.5 hours. After completion of the reaction, which is controlled by known methods for the absence of free MA, the resulting suspension is filtered. The precipitate is dried to constant weight.

The weight of the precipitate is 61.5 g. Yield - 97.7%.

Example 3

In the reactor according to example 1, 223.4 g of a 20% solution of Acetononyl H in toluene is poured, which corresponds to 0.258 mol of a substance in terms of TMDCH monomer. While stirring, an equimolar amount (30.3 g) of MA is added to the solution, and the temperature of the mixture is raised to 80 ° C. The mixture was kept at this temperature for 3 hours until there was no free MA. A suspension is obtained which clogs the paper filter during filtration, which indicates the low technological quality of the selected reaction temperature.

Example 4

Illustrates the effect of the reaction product of the solution of Acetononil N with MA (AAA) according to Example 1 as proposed in the invention as a synthetic PI modifier SKI-3 in comparison with the known prototype compounds - N-4-diphenylaminomaleamic acid - DFMAK with a melting point of 184 ° C and N-cyclohexylmaleamic acid - CMAC with a melting point of 141 ° C.

In a closed laboratory mixer with a volume of 700 cm ³ , or in a Brabender plastic recorder with a chamber volume of 350 cm ³ , with a loading degree of at least 0.95, with a rotor speed of 70-80 rpm and an initial temperature of the chamber walls of 100 ° C for 30-90 seconds according to the recipe shown in Table 1, uterine mixtures are made on the basis of 600 (plastic 315) grams of PI brand SKI-3 of the second plasticity group according to GOST 14925-79 with samples DFMAK and TsMAK - according to the prototype and with AAAA according to the invention . In this example, modification initiators are not used. At the end of the mixing cycle, the temperature of the mixture is brought up to 200 ° C by known methods and the mixture is treated at this temperature for 70 seconds, after which the modified PI is unloaded from the mixer (or plastic scraper).

After resting for 2 hours, the resulting masterbatch is used to make carbon-filled rubber compounds according to the recipe shown in Table 2, according to the usual two-stage regimen.

At the first stage of mixing, carried out on the same mixing equipment that was used to modify the PI, at the initial temperature of the walls of the mixer 100 ° C, modified PI is introduced at the beginning of mixing, then at the 30th second zinc oxide, stearic acid and half of the amount specified in the recipe are introduced the mass of the control carbon black P-324, at the 90th second - half the rest of the carbon black and oil, after which the temperature of the chamber walls by known methods is maintained so that the unloaded mixture has a temperature not lower than 130-140 ° C for a total mixing time of 220-240 seconds.

At the second stage of mixing, carried out on laboratory rollers with dimensions of 160 × 320 mm at a roll temperature of 75 ± 5 ° C, an accelerator and sulfur are introduced at a total mixing time of no more than 5 minutes; at the end of the mixing cycle, three-sided trimming of the mixture is performed, releasing it at the gap between the rolls of 2 mm. The rubber compound plates with a thickness of 2 ± 0.1 mm can withstand a day, after which standard (according to GOST 270-75) double-sided blades with a working section width of 6 mm are cut out for determining cohesive strength according to known methods at a speed of spreading the clamps of a tensile testing machine 200 mm in a minute. The values of the conditional stresses under tension of the mixture samples by 300% (M300) and the values of tensile (cohesive) strength in MPa are measured.

In the remaining rubber compounds, resistance to vulcanization and vulcanization characteristics are determined on a Monsanto 100S rheometer at 160 ° C, after which standard plates 2 mm thick at 150 ° C are vulcanized for 20 minutes to determine the physical and mechanical properties of the vulcanizates.

The results of the determination of cohesive strength, vulcanization characteristics of rubber compounds and physicomechanical properties of vulcanizates are shown in Table 3.

As can be seen from table 3, in rubber mixtures based on SKI-3 modified with an AAA additive according to the invention, the increase in cohesive strength occurs to a greater extent than in mixtures based on SKI-3 samples modified with DFMAK and TsMAK additives proposed by the prototype and taken in the same dosage. Moreover, the level of vulcanization characteristics and resistance to vulcanization mixture according to the invention is practically not inferior to the control and mixtures with modifiers of the prototype. However, in terms of physical and mechanical properties, rubber based on a mixture of SKI-3 with AAA according to the invention has distinct advantages over the control and rubbers from SKI-3, modified additives according to the prototype. This is especially noticeable in terms of tear resistance.

Example 5

It illustrates the effect of the AAAMA product proposed according to the invention as a SKI-3 rubber modifier used in conjunction with the free radical modification initiators proposed according to the invention: hexachloro-n-xylene (GHPC) or bis-triethoxysilylpropyltetrasulfide (TESPT) in comparison with the action of the well-known prototype CMAC taken together with the inventive mecaptobenzthiazolyl disulfide (altax).

To this end, under the conditions described in Example 4, a masterbatch of rubber SKI-3 with 0.4 wt.h. CMAC and 0.05 parts by weight altax, as the initiator of the prototype, as well as a mixture of SKI-3 with AAAA made according to Example 2, with the initiators of GHPK or TEPST. Used in the example, the dosage of additives according to the prototype and according to the invention, taken to modify SKI-3, are shown in Table 4.

The modification of the resulting master batch is carried out according to Example 4 at a discharge temperature of 180 ° C and a processing time at this temperature of 60 seconds.

After resting for 2 hours, the resulting masterbatches are used to make carbon-filled rubber compounds according to the recipe shown in Table 2, according to the usual two-stage mode, as in Example 4. Next, plates are prepared from the obtained mixtures according to Example 4 for determining cohesive properties, and the remaining mixtures are used to determine their technological properties and physico-mechanical characteristics of the vulcanizates obtained from them.

The relevant data are presented in Table 5.

As can be seen from table 5, the modification of the SKA-3 rubber with the ААМА product at a low temperature of 180 ° С in the absence of an initiator gives higher cohesive strength values than the same modification of the CMAC product according to the prototype. In the presence of an altax initiator, the effectiveness of CMAC increases, however, the resistance to vulcanization and the viscosity of rubber compounds are significantly reduced. In comparison, the initiators proposed according to the invention provide a more significant increase in cohesion strength and stress values at 300% elongation than in rubber compounds with rubber SKI-3, modified TsMAK and altax (according to the prototype), and also the best physic -mechanical indicators of vulcanizates while maintaining or improving the resistance of rubber compounds to vulcanization.

Example 6

Illustrates the effect of the composition according to the invention, the composition of which uses the AAA sample of the invention obtained according to Example 3, with the components of the modifying composition taken in ratios different from Example 5, in comparison with the action of the composition of the prototype.

Table 6, which shows the properties of rubber compounds and rubbers obtained according to Example 6, shows the composition of the modifying systems used. The processing conditions of masterbatches from SKI-3 are as in Example 4 (at 200 ° C for 70 seconds).

As can be seen in table 6, the compositions proposed according to the invention provide higher cohesive strengths of unvulcanized rubber compounds than the prototype composition, and in contrast to the mixture modified by the prototype composition, the mixtures modified by the compositions of the invention have better technological properties - higher resistance to vulcanization, better retention of viscosity after modification, and a better set of properties of rubbers obtained by vulcanization of mixtures.

Example 7

Illustrates the effect of the invention according to the invention of a multifunctional AAA made according to Example 1 based on a solution of Acetononil H taken from an industrial process after the second stage of synthesis - oligomerization, in comparison with a monofunctional MMK - AAA monomer obtained in the conditions of Example 1 from an industrial solution taken after the first stages of synthesis, leading to the formation of the actual monomer TMDHC, when oligomers in the mixture are practically absent. Example 7 also illustrates the effectiveness of the proposed according to the invention TEPST initiator in comparison with the altax of the prototype when used in combination with the AAA sample obtained in Example 1.

Table 7, which shows the properties of rubber compounds and rubbers obtained according to Example 7, shows the composition of the modifying systems used. The processing conditions of masterbatches from SKI-3 are as in Example 4 (at 200 ° C for 70 seconds).

As can be seen from the table, the monofunctional MMK - AAA monomer is a less effective rubber modifier SKI-3 than the polyfunctional AAA, both when using the TEPST initiator according to the invention (mixture 20) and in its absence (mixture 17).

Used Books

1. R. P. Lattimer, E. R. Hooser, P. M. Zakriski, Rubber Chemistry and Technology, 1980, v. 53, pp. 346-356.

Table 1.
Dosage modifiers in SKI-3 according to the prototype and according to the invention in parts by weight per 100 parts by weight of rubber Modifier Name Samples of modified SKI-3 Without modifier 1 - counter. 2 prototype 3 prototype 4 pic. DFMAK (prototype) - 0.6 - - CMAC (prototype) - - 0.6 - AAMA (according to the invention) - - - 0.6

Table 2.
The composition of carbon-filled rubber compounds made from modified and control SKI-3 (in parts by weight) to assess cohesive properties Ingredients Rubber compounds I-th mixing cycle (rubber mixer or plastic mixer) unload. at 140 ° C Reference SKI-3 one hundred - Modified SKI-3 - one hundred Zinc oxide 5,0 5,0 Stearic acid 2.0 2.0 Technical carbon, control P-324 50,0 50,0 PN-6 oil 5,0 5,0 II-nd mixing cycle (rollers) at 75 ± 5 ° С Sulfur 2.0 2.0 Sulfenamide C 0.8 0.8

Table 3.
Properties of rubber compounds based on control and modified SKI-3 samples and rubber obtained from them Indicators The composition of the modifying composition control b / mod DFMAK 0.6 TsMAK 0.6 AAAMA. 0.6 one 2 3 four Rubber Testing Mooney viscosity before modification at 100 ° C, at 4 minutes / elastic. recovery 69.0 / 9.6 73.0 / 10.6 72.0 / 9.8 73.0 / 10.4 Mooney viscosity at 100 ° C, 4 minutes after modification at 200 ° C / ellastic. recovery 63.0 / 4.9 64.0 / 6.5 65.0 / 6.0 65.8 / 6.2 Rubber Testing Mooney viscosity at 100 ° C (for 4 min.) 64 78 85 88 Conditional stress at 300% elongation, MPa 0.16 0.20 0.22 0.25 Cohesive strength, MPa 0.22 0.42 0.61 0.89 Relative extension, % 1300 1150 1000 1100 Mooney vulcanization resistance at 130 ° С: t 5, min
t 35 min
16.5
20,2
14.5
17.5
15.3
18.9
17.0
19.6 Geometrical indicators 160 ° С M _L , f / f 9.5 9.0 8.5 9.5 M _H ff / d 42.9 43.2 42.8 44.5 t _s1 , min 2.7 2.5 2.6 2.6 t ₅₀ min 5.0 4.8 4.9 4.8 t ₉₀ min 7.0 6.0 7.0 8 Testing carbon black filled vulcanizates (vulcanization at 150 °, 20 min) Conditional stress at 300% elongation, MPa 14.1 15.0 14.8 15.5 Tensile strength, MPa 22.2 23.7 23.2 24.8 Relative extension, % 460 400 440 400 Tear resistance, N / m 83.9 93.0 89.0 104.0

Table 4.
Dosages of modifiers and initiators in masterbatches based on SKI-3 according to the prototype and according to the invention in parts by weight Modifier Name Samples of modified SKI-3 5 6 7 8 9 10 counter. prototype according to the invention CMAC - 0.4 0.4 - - - Altax - - 0.05 - - - AAAMA - - - 0.4 0.4 0.4 GHPK - - - - 0.02 TEPST - - - - - 0.02

Claims (2)

1. N-substituted maleamides of maleamic acid (MMK) obtained by the interaction of compounds with amino groups with maleic anhydride (MA) when heated in an anhydrous solvent, followed by separation of the precipitate of the finished product from the solvent used to modify the synthetic cis-1,4-polyisoprene (PI), characterized in that as compounds with amino groups using a mixture of oligomers of the heterocyclic monomer 2,2,4-trimethyl-1,2-dihydroquinoline (TMDHC), obtained after the second stage of the synthesis of industrial production Acetononyl H, with synthesis by-products - primary and secondary mono-, di- and polyamines in the form of a 15-20% solution in toluene (Acetononil H solution), toluene is used as a solvent, reagents are taken in an equimolar ratio based on the molar content in dry Acetonanil N of the TMDMH monomer, and the MMCs formed as a result of the reaction are multifunctional. 2. Composition for the modification of cis-1,4-polyisoprene, including MMK in combination with free radical initiators of modification, characterized in that as the MMK use the multifunctional reaction products of a solution of Acetononil H in toluene with MA according to claim 1, and as free radical initiators use hexachloro-n-xylolol (HCCH) or a liquid organosilicon compound - bis-triethoxysilylpropyltetrasulfide (TESPT), in the following ratios of components of the modifying composition, parts by weight: Multifunctional MMK 0.4-1.0 GHPK or TESPT 0.02-0.10