RU2246506C2 - Antiager of vulcanized rubber - Google Patents

Abstract

FIELD: organic chemistry, rubber industry.

SUBSTANCE: invention relates to a chemical compound, namely to polyaniline (poly-p-phenyleneamineimine) that is used as an antiager for rubbers. Polyaniline of the formula:

wherein m = n = 1 with molecular mass 25 x 10³ Da is used as an antiager. Invention provides enhancing thermostability of vulcanized rubbers.

EFFECT: improved and valuable properties of antiager.

2 tbl, 2 ex

Description

The invention relates to a chemical compound, namely to polyaniline (poly-p-phenyleneaminimine), which can be used as an antioxidant of rubbers.

It is known that polyaniline finds practical application as a polymer that conducts electric current, as an electrode material (Surville R. de, Zozefowicz M. Yu LT et al. // Electrochim. Acta. 1968. Vol. N 6. HP1451-1458) , to obtain highly effective synthetic fibers (Chem. a. Fng News. // 1991. - V.69. - No.17. - p.8). Polyaniline finds practical application in electronics and nonlinear optics (Chan H. S. O., Ng S. S. E. E. A. Macromolecules. 1992. - V.25. - No.22. - P.6029-6034.).

2.2,4-trimethyl-1,2-dihydroquinoline (acetonanil) is known. (Abstracts of the 1st Kirpichnikov readings "Destruction and stabilization of polymers. Young scientists - the third millennium". Kazan, February 22-24, 2000, New Knowledge).

However, with the introduction of this antioxidant, the vulcanizates are characterized by low heat resistance.

The use of crotonilidene-α-naphthylamine dimer as an antioxidant is known.

However, its inhibitory activity is not high enough. In addition, crotonic aldehyde is used in its preparation, which under the synthesis conditions (t = 140 ° C) tends to polymerize, as well as a large amount of catalyst - up to 10% (oxalic acid or benzenesulfonic acid), which leads to contamination of the product. (Handbook of rubber worker. - M .: Chemistry, 1971, p. 324).

When using crotonilidene-α-naphthylamine as an antioxidant for rubbers, an additional introduction of protective wax into the rubber mixture (ceserin 80) is required.

In addition, the indicators of heat resistance of vulcanizates are low.

It is also known to use N-phenyl-m-phenoxyphenylmethanimine (RF patent N 2116999, IPC C 07 C 251/24, C 08 K 5/29, 1996), No-hydroxyphenyl m-phenoxyphenylmethanimine (RF patent N 2117000, IPC C 07 C 251/24, C 08 K 5/29, 1996) and N-p-methoxyphenyl-m-phenoxyphenylmethanimine (RF patent N 2117001, IPC C 07 C 251/24, C 08 K 5/29, 1996) as antioxidants combining the properties of antiozonants and anti-fatigue agents.

However, the test results of properties such as conditional tensile strength, elongation using these substances are inferior to the results obtained using the inventive substance.

The closest in structure and purpose is N-phenyl-N-cyclohexyl-p-phenylenediamine (brand 4010) (Handbook of rubber worker. - M .: Chemistry, 1971, S. 608).

However, the introduction of the specified antioxidant vulcanizates do not have high heat resistance.

The objective of the invention is to obtain a new antioxidant, which, when introduced into the rubber mixture, provides rubber products that are resistant to heat aging.

The technical result when using the proposed compound is to increase the heat resistance of vulcanizates.

The technical result is achieved by the fact that as an antioxidant of rubbers using polyaniline of the formula

molecular weight 25 · 10 ³ .

The polyaniline we offer is obtained by reacting an aromatic amine, namely aniline, with ammonium persulfate.

The structure of polyaniline includes secondary aromatic amine units and quinoneimine structures, which ensures the inhibition of various types of radicals: R, RO, RO ₂ , the formation of which is characteristic of the oxidation of rubber.

Inhibition of polydienes oxidation by polyaniline is based on the following transformations:

Polymer radicals resulting from the destruction of polydiene react with quinoid fragments of the polyaniline structure and thereby carry out specific regeneration of the molecular weight of the polymer, ensuring the heat resistance of the rubber.

Polyaniline is prepared by the classical polycondensation reaction of aromatic amines. / A.V. Volokhina. The use of polyaniline to produce promising synthetic fibers. Chemical fibers, 1994, No. 1, pp. 11-14 /.

Aniline is reacted with ammonium persulfate in the presence of a solution of hydrochloric acid at a temperature of -5-0 ° C for 2-2.5 hours and 86 ° C for 1 hour.

Polyaniline is purified from unreacted starting reagents and secondary oxidation products by extraction with acetone. Polyaniline is a dark green powder, soluble only in concentrated sulfuric acid.

The invention is illustrated by the following examples.

Example 1. In a four-necked reactor equipped with a stirrer, a thermometer, a reflux condenser and a dropping funnel, 9.3 g (0.1 mol) of aniline, 20 ml of distilled water, 7.25 g (0.2 mol) of hydrochloric acid are charged. With stirring and at zero temperature, a solution of ammonium persulfate 11.4 g (0.05 mol) is dosed. The reaction mixture is maintained at t = 18-20 ° C for 24 hours. Then heated at t = 86 ° C for 1 hour. The final product is purified by extraction with acetone in a Soxhlet apparatus, dried in vacuum at 50 ° C. The resulting salt is transferred to the base when treated with an aqueous solution of sodium hydroxide. Yield 86%.

Found,%: C 78.96, H 4.59, N 16.45.

Calculated,%: C 79.54, H 5.01, N 15.45.

IR spectrum, ν, cm ^-1 : 1580 (C = C); 3070 (CH), 3310 (NH), 1230 (CN), 1580 (N-H).

Molecular mass: 25 · 10 ³ .

The intrinsic viscosity was determined by measuring the reduced viscosity of solutions of products in concentrated sulfuric acid at a temperature of 20 ° C. The molecular masses of the polymers were calculated using the Mark-Houwink equation.

The IR spectra of the samples were recorded on a Specord M 82 spectrophotometer. Differential-thermal analysis was performed on a derivatograph system F. Paulik, I. Paulik and L. Erdei.

Example 2. Polyaniline is tested in standard rubbers, the composition of which is indicated in table 1.

Table 1
The composition of the rubber compound Rubber Compound Components Mass composition K ₁ Prototype The proposed mixture K ₂ K ₃ 1 2 3 4 Isoprene synthetic rubber, SKI-3 100 100 100 Vulcanizing agent-sulfur 1 1 1 Vulcanization activator-zinc oxide 5 5 5 Stearin 1 1 1 Vulcanization Accelerator Altax 0.6 0.6 0.6 Diphenylguanidine 3 3 3 4010 Antioxidant - 1,1 - Polyaniline - - 1,1

Polyaniline is administered instead of the antioxidant N-phenyl-N′-cyclohexyl-p-phenylenediamine (grade 4010) in an amount of 1.1 parts by weight per 100 parts by weight of rubber. Physico-mechanical properties - conditional tensile strength, elongation, residual elongation - are determined in accordance with GOST 270-75. The effectiveness of polyaniline as an antioxidant in rubber was evaluated in comparison with a 4010 antioxidant. Aging was carried out at a temperature of 100 ° C for 72 hours. The test results are presented in table 2.

table 2
Test results Properties K ₁ Prototype The proposed mixture K ₂ K ₃ Conditional tensile strength, MPa 31.5 31,0 30.5 Relative extension, % 870 850 900 Residual elongation,% eighteen 16 eighteen ISO hardness, conv. units 37 35 35 Indicators after 72 hours of aging at 100 ° C Conditional tensile strength, MPa 16 22 24 Relative extension, % 600 650 700 Residual elongation,% 10 8 8 ISO hardness, conv. units 45 40 40

As can be seen from the data presented, polyaniline is an effective antioxidant of rubber. The relative elongation after aging increased by 8% compared with the prototype. Conditional tensile strength increased by 10%. Other indicators remained unchanged.

Thus, the above information indicates the fulfillment of the following set of conditions when using the claimed invention: the agent embodying the claimed invention when used is intended to be used as an antioxidant of rubbers; for the claimed invention in the form described in the claims, the possibility of its implementation using the means and methods described in the application and known prior to the priority date is confirmed; means embodying the claimed invention in its implementation, is able to achieve the technical result.

Therefore, the claimed invention meets the requirement of "industrial applicability".

Claims (1)

The use of polyaniline of the formula:

where m = n = 1, molecular weight 25 · 10 ³ as an antioxidant of rubber vulcanizates.