RU2224769C2 - Method of preparing stabilizer and polyisoprene composition containing thereof - Google Patents

Abstract

FIELD: rubber industry. SUBSTANCE: alkylphenol is mixed and heated to 130-140 C with hexamethylenetetramine and N-isopropyl-N'-phenyl-pphenylenediamine at their weight ratio (4-10):1:(1-3) to give product with softening temperature 60-75 C. The product is supplemented by 1-7 wt parts of maleic anhydride per 1 wt part of hexamethylenetetramine and heating at 130-140 C is continued. Before addition of maleic anhydride, toluene may be added at 50-60 C to form 30-60% solution followed by heating at 50-90 C until process is completed. Polyisoprene composition includes isoprene rubber and 0.5-2% of above-described stabilizer. EFFECT: increased cohesive resistance of rubber compounds, increased 300%-elongation engineering stress leading to better workability of rubber. 2 cl, 1 tbl, 8 ex

Description

 The invention relates to the field of production of stabilizers and polymer compositions based on polyisoprene and can be used in industry in the manufacture of compositions and rubbers from these compositions.

 The problem of synthesizing an effective stabilizer is extremely important, as it allows us to solve the problem of protecting polymer materials from aging during their isolation, processing and storage.

 From the point of view of practical application of the greatest interest are high molecular weight stabilizers based on alkyl phenol resins.

 A known method of producing a stabilizer by condensation of phenol selected from the group consisting of p-cresol, p-tert-butylphenol, 3.4 xylene, p-bromophenol, p-octylphenol, p-nonylphenol, with hexamethylenetetraamine (HMTA) (ed. Certificate of the USSR 540886 , C 08 L 9/00, publ. 30.12.76).

 However, the stabilizer obtained in this way is not sufficiently effective, and polyisoprene compositions with its use give a low level of cohesive strength. So according to the authors of this application, a composition containing polyisoprene and 0.05-3.0 wt.% Stabilizer, has a cohesive strength of ~ 0.15 MPa.

A known method of producing phenolamine resins capable of being used as a stabilizer of polymer compositions based on unsaturated elastomers. The method consists in the condensation of alkyl phenols with HMTA in the presence of a modifying agent - still residue of styrene rectification in the amount of 5-50% by weight of the starting reagents at 130-175 ^o С (ed. Certificate of the USSR 1263697, С 08 G 14/073, С 08 L 9/00, publ. 10/15/86).

 However, the stabilizers obtained in this way also do not provide sufficiently effective protection of polymers against aging and do not provide optimal values for the conditional stress modulus at 300% elongation of crude rubber compounds based on a polyisoprene composition containing polyisoprene and a stabilizer.

 The closest analogue of the proposed method according to the technical essence and the achieved result is a method for producing a stabilizer, which consists in the condensation of alkyl phenol (AF) selected from the group consisting of p-tertiary butylphenol, p-octylphenol, p-nonylphenol with HMTA and N-isopropyl-N ' '-phenyl-p-phenylenediamine (diaphen-FP) with their mass ratio (4-10): 1: (1-3), respectively (RF patent 2069668, C 08 G 8/28, C 08 L 9/00, publ. . 11/27/96).

The process of obtaining a stabilizer is carried out in three stages. First, at a temperature of 60-80 ^o C, the mixture of components is brought to a solution state, then the temperature is increased to 140 ^o C and maintained for 2-3 hours, removing moisture from the solution, and then at a temperature of 130-150 ^o C the reaction mixture is kept 5- 10 hours. The resulting stabilizer is a resin with a molecular weight of 500-800, a melting point in the range of 60-75 ^o C and the content of the bound N-isopropyl-N'-phenyl-p-phenylenediamine 10-35 wt.%.

 Compared with the above, this method allows to obtain a stabilizer that provides more effective protection of polymeric materials from aging. The disadvantage of this method is that the obtained stabilizer does not provide optimal values for the conditional stress modulus at 300% elongation of raw rubber compounds and vulcanizates based on the polyisoprene composition and does not allow to increase the cohesive strength of the composition. So the polymer composition, which is the closest in composition and the achieved positive effect, including cis-1,4-polyisoprene and a stabilizer obtained by condensation of AF, HMTA and AF diaphen, in an amount of 0.1-1.5 wt.%, On polyisoprene has a cohesive strength of ~ 1 MPa.

 However, the above indicators are essential for the further processing of rubber into products, such as large tires.

 The objective of the invention is to develop a method for producing a stabilizer, the use of which would increase the cohesive strength of the composition based on synthetic isoprene rubbers and improve their processability.

The problem is achieved in that after the interaction of AF, HMTA and AF diaphene with their mass ratio (40-10): 1: (1-3) when heated at 130-140 ^o C and stirring to obtain a product with a softening temperature of 60-75 ^o With the resulting product is introduced maleic anhydride (MA) in an amount of 1-7 wt.h. per 1 part by weight HMTA and continue heating for 1-2 hours.

In the case of the reaction of interaction with MA in the solution, before MA is fed, toluene is introduced into the resulting product at 50-60 ^{° C.} until a solution with a concentration of 30-60 wt.% Is formed.

 This problem is also solved by the fact that the polyisoprene composition, consisting of polyisoprene and a stabilizer, contains as a stabilizer the stabilizer obtained by the above methods in an amount of 0.5-2.0 wt.% Per rubber.

 The technical result of the proposed method is that the stabilizer synthesized in this case allows to obtain higher values of cohesive strength (not less than 2.0 MPa) and modulus at 300% elongation (not less than 0.5 MPa) for unvulcanized rubber mixtures prepared on based on polyisoprene compositions, which is a significant achievement in the field of modification of synthetic polyisoprene.

The essence of the method of obtaining a stabilizer is as follows. A mixture of components: AF, HMTA and AF diaphen is brought to a solution state with stirring and a temperature of 60-80 ^o С, and then the reaction mass is heated to 130-140 ^o С and stirring is continued for 5-14 hours to obtain a product with a softening temperature of 60 -75 ^o With, then injected MA in an amount of 1-7 wt.h. per 1 part by weight HMTA and continue heating for 1-2 hours.

The process can be carried out both in bulk and in solution. As a solvent, toluene is usually used, which is introduced into the reaction mass before MA is fed. The supply of toluene is carried out at a temperature of 50-60 ^o C. From the point of view of technology, it is optimal to carry out the process at a solution concentration of 30-60 wt.% And the temperature of interaction with MA 50-90 ^o C.

MA can be used both in dry form and as a solution in toluene. The heating time after the introduction of MA depends on the temperature of this stage of the process. When carrying out the reaction in bulk, it should be heated for 1-2 hours at 130 ^o C. In a toluene solution, the reaction proceeds efficiently in a fairly short time (30 minutes - 2 hours) at a temperature of 50-90 ^o C depending on the concentration of reagents in toluene. The resulting product is unloaded, cooled and used as a stabilizer of isoprene rubbers. As alkyl phenols, individual products, for example p-nonylphenol, p-octylphenol, etc., as well as mixtures thereof, both specially prepared and manufactured in industry, for example monoalkylphenols according to TU 38.602-09-20-91, can be used.

 To determine the effectiveness of the obtained product, a polyisoprene composition is prepared as a stabilizer. For this, isoprene is polymerized in a hydrocarbon solvent in the presence of a catalyst and 0.5-2 wt% is added to the polymer of the stabilizer obtained by the above method in the form of a solution in toluene. After isolation and drying, the plasticity retention index of the composition is determined, which characterizes the antioxidant properties of the stabilizer; a crude rubber mixture is prepared on the basis of the polyisoprene composition, the conditional stress modulus is determined at 300% elongation of the mixture and its cohesive strength.

The plasticity conservation index is determined by the following method: 20 g of a composition containing a synthesized stabilizer is passed 3 times through rollers or calender at room temperature. The composition is released in the form of skins with a thickness of 1.6-1.8 mm Then the skin is folded in half and tightly pressed by hand. Washers are cut from a skin with a special knife ~ 3.5 mm thick and 10 mm in diameter. Three washers are placed in a thermostat, in which the temperature is maintained at 140 ± 0.2 ^° C, and held there for 30 minutes. Then, the ductility according to Wallace is determined and the average value is calculated. The ductility of 3 initial samples is determined and their average value is also found. The plasticity conservation index is the ratio of the plasticity of the oxidized composition to the plasticity of the original composition, expressed as a percentage.

Based on the composition containing the obtained stabilizer, prepare the rubber mixture according to the following recipe, parts by weight:
Polyisoprene Composition - 100.0
Zinc white - 5.0
Stearic Acid - 2.0
Sulfur - 2.0
Sulfenamide C - 0.80
Carbon black - 50.0
For this, the composition is mixed with the ingredients on the rollers at a front roll rotation speed of 23-25 rpm and a roll surface temperature of 90 ± 5 ^o C. From the resulting rubber compound sheet 2.0 ± 0.2 mm thick, a plate of 120x140 mm is cut out and cooled at room temperature.

Next, the plate is placed in a drying Cabinet, heated to a temperature of 100 ± 3 ^o C, and incubated in it for 80 minutes Then the plate is removed from the thermostat, kept at room temperature for at least 60 minutes. Five samples are cut from the plate in the direction of rolling with a knife of type 1 in accordance with GOST 270 and their tests are carried out in accordance with GOST 270, namely, they determine the conditional stress at 300% elongation and cohesive strength of the samples, after which their average value is found.

 The invention is illustrated by the following examples.

 Example 1

 In a flask equipped with an overhead stirrer, 89.4 g of p-nonylphenol, 14.9 g of HMTA and 26.8 g of FP diaphene are charged (ratio of reagents AF: HMTA: FP-6.0 diafen: 1.0: 1, 8). The flask is placed in an oil thermostat, in which silicone oil is heated by means of electric heaters mounted on the walls. The temperature in the thermostat is regulated by a contact thermometer with an isodrome.

The reagent mixture is brought to the state of the solution at a temperature of 60 ^{° C.} with constant stirring for 4 hours, then the temperature is increased to 130 ^{° C.} and a condensation reaction is carried out at 130 ^{° C.} for 10 hours to obtain a product having a softening temperature of 70 ^{° C.} , after why at the same temperature 29.8 g of MA are introduced into the reaction mass in the form of granules (2 parts by weight of MA per 1 part by weight of HMTA), the reaction is carried out for 1 hour, then the resulting product is unloaded and its softening temperature is determined. After polymerization of isoprene in isopentane in the presence of a catalyst: triisobutylaluminum and titanium tetrachloride, the synthesized stabilizer is introduced into the polymerizate in the form of a solution in toluene in an amount of 2 wt.% (Dry matter) on polyisoprene. Next, the catalyst residues are deactivated, degassed to remove the solvent, dried, and the plasticity retention index of the composition and the properties of the crude rubber composition obtained on the basis of the polyisoprene composition are determined.

 The test results are shown in the table.

 Example 2

Under the conditions described in example 1, 149 g of a mixture of alkyl phenols containing equal amounts of p-octyl and p-nonylphenol, 14.9 g of HMTA and 44.7 g of diafen FP are charged (ratio of reagents AF: HMTA: diafen FP 10.0: 1 , 0: 3.0). These reagents are brought to a solution state at a temperature of 60 ^{° C.} with constant stirring for 6 hours, then the temperature is raised to 130 ^{° C.} and a condensation reaction is carried out at this temperature for 14 hours. A product is obtained having a softening temperature of 60 ^{° C.} , after which at 130 ^{° C.} 59.6 g of MA are introduced into the reaction mass in the form of a melt (4 parts by weight of MA per 1 part by weight of HMTA), the reaction is carried out for 2- x hours, then the resulting product is discharged and its softening temperature is determined.

 In the polymerizate obtained as described in example 1, synthesized stabilizer is introduced in an amount of 1.5 wt.% Per polyisoprene. After deactivation of the catalyst residues, degassing and drying, the plasticity retention index of the composition and the properties of the crude rubber composition obtained from the polyisoprene composition are determined.

 The test results are shown in the table.

 Example 3

74.5 g of monoalkylphenols (TU 38.602-09-20-91), 14.9 g of HMTA and 29.8 g of AF diaphen (ratio of reagents AF: HMTA: diafen FP 5.0 are charged into a flask equipped with an overhead stirrer with top drive : 1.0: 2.0). The reagents are brought to the state of the solution at a temperature of 60 ^{° C.} with constant stirring for 8 hours, then the temperature is increased to 140 ^{° C.} and a condensation reaction is carried out at this temperature for 5 hours to obtain a product having a softening temperature of 73 ^° C. The temperature is lowered to 135 ^{° C.} and 22.4 g of MA are introduced into the reaction mixture in the form of granules (1.5 parts by weight of MA per 1 part by weight of HMTA), the reaction is carried out for 1 hour, the resulting product is unloaded and its softening temperature is determined.

SKI-3 rubber is mixed on rollers with a synthesized stabilizer at a temperature of 90-95 ^o C, while the amount of stabilizer is 0.5 wt.% Per polyisoprene. Then determine the index of preservation of the ductility of the composition and the properties of the crude rubber compound obtained on the basis of the polyisoprene composition.

 The test results are shown in the table.

 Example 4

Under the conditions of Example 1, 119.2 g of p-octylphenol, 14.9 g of HMTA and 26.8 g of AF diaphen were loaded (ratio of reagents AF: HMTA: diaphen AF (8.0: 1.0: 1.8). The reagents were adjusted to the state of the solution at 60 ^{° C.} for 4 hours, then the temperature is raised to 130 ^{° C.} and a condensation reaction is carried out at this temperature for 12 hours to give a product having a softening temperature of 68 ^{° C.} , and then the temperature is raised to 140 ^° C and enter 104.3 g of MA in the form of granules (4 parts by weight of MA per 1 part by weight of HMTA), carry out the reaction for 1 hour, unload the resulting product and determine its temperature ru softening.

 In the polymerizate obtained as described in example 1, synthesized stabilizer is introduced in an amount of 2.0 wt.% Per polyisoprene. After deactivation, degassing and drying, the index of preservation of the ductility of the composition and the properties of the crude rubber compound obtained on the basis of the polyisoprene composition are determined.

 The test results are shown in the table.

 Example 5

Under the conditions of Example 1, 59.6 g of monoalkylphenols (TU 38.602-09-20-91), 14.9 g of HMTA and 16.4 g of AF diaphen (ratio AF: HMTA: AF diaphen 4.0: 1.0: 1 are charged ,1). The reagents are brought to a solution state at a temperature of 70 ^{° C.} with constant stirring for 3 hours, then the temperature is increased to 130 ^{° C.} and a condensation reaction is carried out at this temperature for 12 hours to obtain a product having a softening temperature of 75 ^{° C.} , and then reduced a temperature of up to 50 ^{° C.} and an amount of toluene is introduced with stirring such that the concentration of the obtained product in the solution is 60%. Then, at the same temperature, 14.9 g of MA are introduced with constant stirring in the form of a solution in toluene (1 part by weight of MA per 1 part by weight of HMTA) and the reaction is carried out for 30 minutes. The obtained toluene stabilizer solution is used to obtain a polyisoprene composition, which is prepared as in Example 1, while the stabilizer is introduced in an amount of 1.1 wt.% On a dry matter basis on polyisoprene.

 After decontamination, degassing and drying of the composition, the same indicators are determined as in example 1.

 The test results are shown in the table.

 Example 6

Under the conditions of Example 1, 74.5 g of monoalkylphenols (TU 38.602-09-20-91) are charged. 14.9 g of HMTA and 14.9 g of diaphen AF (ratio of reagents AF: HMTA: diaphen AF 5.0: 1.0: 1.0). The reagents are brought to a solution state at a temperature of 80 ^{° C.} with constant stirring for 3 hours, then the temperature is increased to 135 ^{° C.} and a condensation reaction is carried out at this temperature for 8 hours to obtain a product having a softening temperature of 71 ^{° C.} , and then reduced a temperature of up to 50 ^{° C.} and a quantity of toluene is introduced with stirring such that the concentration of the obtained product in the solution is 40% by weight. Then, the temperature is raised to 90 ^{° C.} and 26.8 g of MA are added with constant stirring in the form of a solution in toluene (1.8 parts by weight of MA per 1 part by weight of HMTA) and the reaction is carried out for 30 minutes. The resulting toluene stabilizer solution is used to obtain a polyisoprene composition, which is prepared as in example 1, while the stabilizer is introduced in an amount of 1.7 wt.% On a dry matter basis on polyisoprene.

 Next, determine the same indicators as in example 1.

 The test results are shown in the table.

 Example 7

Under the conditions of Example 1, 88.3 g of monoalkylphenols (TU 38.602-09-20-91), 14.9 g of HMTA and 28.3 g of AF diaphen are loaded (ratio of reagents AF: HMTA: AF diaphen 6.6: 1.0: 1.9). The reagents are brought to a solution state at a temperature of 60 ^{° C.} with constant stirring for 5 hours, then the temperature is increased to 135 ^{° C.} and a condensation reaction is carried out at this temperature for 10 hours to obtain a product having a softening temperature of 73 ^{° C.} , and then reduced a temperature of up to 50 ^{° C.} and a quantity of toluene is introduced with stirring such that the concentration of the obtained product in the solution is 30% by weight. Then, at the same temperature (50 ^{° C.} ) and with constant stirring, 41.7 g of MA are introduced in the form of granules (2.8 parts by weight of MA per 1 part by weight of HMTA) and the reaction is carried out for 1 hour. The obtained toluene stabilizer solution is used to obtain a polyisoprene composition which is prepared as in example 1, while the stabilizer is introduced in an amount of 1.8 wt.% On dry matter per polyisoprene.

 Next, determine the same indicators as in example 1.

 The test results are shown in the table.

 Example 8 (control).

Under the conditions of Example 1, 96.9 g of p-nonylphenol, 14.9 g of HMTA and 23.8 g of AF diaphen were loaded (ratio of reagents AF: HMTA: AF diaphen 6.5: 1.0: 1.6). The reagents are brought to a solution state at a temperature of 60 ^{° C.} with constant stirring for 7 hours, then the temperature is increased to 135 ^{° C.} and a condensation reaction is carried out at this temperature for 13 hours to obtain a product having a softening temperature of 73 ^° C.

 The resulting product is used to obtain a polyisoprene composition, which is prepared as in example 1, while the stabilizer is introduced in an amount of 1.5 wt.% On polyisoprene and after deactivation, degassing and drying, the same indicators are determined as in example 1.

 The test results are shown in the table.

 Thus, as can be seen from the data given in the table, the polyisoprene composition containing the stabilizer synthesized by the proposed method has an increased cohesive strength of the rubber compounds based on it and has an increased conditional stress at 300% elongation, which generally improves the rubber processability .

Claims (2)

1. A method of obtaining a stabilizer, which consists in the interaction with heating to 130-140 ° C and mixing of alkyl phenol with hexamethylenetetramine and N-isopropyl-N ¹ -phenyl-p-phenylenediamine in their mass ratio (4-10): 1: (1- 3) to obtain a product with a softening temperature of 60-75 ° C, characterized in that then in the resulting product is introduced maleic anhydride in an amount of 1-7 wt.h. per 1 part by weight hexamethylenetetramine and continue heating at 130-140 ° C or before the introduction of maleic anhydride toluene is introduced at 50-60 ° C until a solution with a concentration of 30-60 wt.% is formed and heating is continued at 50-90 ° C until the end of the process. 2. Polyisoprene composition comprising isoprene rubber and a stabilizer, characterized in that as a stabilizer it contains a stabilizer obtained according to the method described in claim 1, in an amount of 0.5-2 wt.% Per rubber.

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