CS235194B1 - Stabilization composition for vulcanizates - Google Patents

Description

CZECHOSLOVAK SOCIALISTIC

(19)

DESCRIPTION OF THE INVENTION

TO CERTIFICATE 235194 (Π) (Ml

(22) Enrolled 20 01 84 (21) (PV 475-84) (51) Int. Cl.5C 08 K 5 / 51C 08 L 5 / 34C 08 K 5 / 13C 08 L 7 / 00C 08 L 11/00 (40) Published 31 08 84

OFFICE OFFICE AND DISCOVERY (45) Published 15 02 87 (75)

Author of the invention HUMPLIK ANTONÍN ing., BRATISLAVA, VOEROES VILIAM ing., PRAGUE, ORLÍK IVO ing., HOLČÍK JÁN ing. CSc., KAČÁNI STANISLAV ing. GSc., BRATISLAVA (54) Stabilizing composition for vulcanizates

BACKGROUND OF THE INVENTION The present invention relates to a stabilizing composition for natural and / or synthetic rubber vulcanisates containing tris (α-methylbenzylphenyl phosphite, α-methylbenzylphenol and 2-mercaptobenzimidazole. The need for high thermo-oxidative stability of natural vulcanizates and However, the use of stabilizers, in particular the phenol group, in the light of their high stability, but their use is limited by their limited availability. A synergistic effect of some mixtures of stabilizers is a viable way to achieve improved thermooxidation stability of the vulcanizates stability to anti-oxidative aging with the product life.

For example Cs. AO 165 480 is a protected combination of aralkylphenol and 2-mercaptobenzimidazole.

In addition, the additive is required and has good workability due to the appropriate finish and solid shelf life, while the current work hygiene requirements and the hassle-free handling of products are increasing. REQUIRED REQUIREMENTS FOR STABILIZING INGREDIENTS A stabilizing composition for vulcanization from natural and / or synthetic rubbers based on 2-mercaptobenzimidazole and n-methylbenzylphenol.

The essence of the invention is that the stabilizing composition comprises

25 to 40% by weight of the trispha-methylbenzylphenyl phosphite of the general formula (c) in which R-represents α-methylbenzyl and n is an integer of 1 to 315 to 30% by weight of 2-mercaptobenzene

of imidazole of formula II

30-60% by weight of a-methylbenzylphenol of formula III 235194 4 233194

OH

(III) wherein n is an integer of 1 to 3, the stages needing treatment with a suitable inert filler with preferably inorganic hydrated silicon dioxide, at an active substance content of 40 to 70, preferably 50 to 65% by weight added to of the vulcanized mixture in an amount of 0.5 to 5.0, preferably 1.0 to 3.0, by weight of the stabilizer component per dose of active ingredient per 100 parts by weight of the elastomer.

The stabilizing composition is used in conjunction with conventional vulcanization accelerators such as guanidines, thiazoles, thiurates and thiocarbamates and the like.

The use of a stabilizing composition according to the invention has many advantages. Since it is a solid and in addition a non-dust treatment, a semi- or full-auto dosing can be used to prepare raw rubber compositions, which significantly improves the working environment.

Since the stabilizing composition of the present invention exhibits a higher antioxidant effect than the binary combination used in the skins and the substantial higher than with the components alone, its application by vulcanizates results in increased resistance to thermo-oxidative aging.

Tab. no. 1

Stabilizer (by weight) α-methylbenzyl phenol 2-mercaptobenzimidazole trisfa-methylbenzylphenyl phosphite

The aging process of vulcanizates was monitored by changing the basic tensile properties, elasticity and hardness after aging of test specimens in the hot air stream at 90 ° C by the GEER method (CSN62 15 21J for 1, 3, 5 and 7 days) From a practical point of view, it is possible to prepare a mixed stabilizer, together with an inert carrier, in powder form and a non-powdery treatment which is substantially more effective than the binary combination used.

The stabilizing composition itself, optionally with another antidegradant, is incorporated into the rubber composition by conventional processing techniques such as other additives.

The properties of the crude mixtures and vulcanizates are monitored and evaluated by conventional tests used in rubber and rubber technology. The following are examples of practical embodiments of the invention. Example 1

Vulcanizate prepared from natural rubber podium of the following recipe. parts by weight natural rubber, type SMR-L 100 acid. zinc 5.0 stearin l, o carbon black, type HAF 35 sulfur 2.25 N-cyclohexyl-2-benzothiazole sulfenamide 0.7 and containing 1.5 wt. parts of the stabilizer were prepared by pressing to an optimum at 145 ° C.

Vulk. the characteristics of the mixtures observed by the MONSANTO methodology at 145 ° C were unaffected by the addition of a stabilizing com- position.

Stabilization Systems 1 2 3 4 5 50 45 40/20 70 15 25 30 30 30 35 30 30 50 - The results obtained are concentrated in the form of a change in the tensile strength from the aging period. The tensile strength of a given type of rubber is a variable that is most pronounced during aging. 235194 5 6

Table 2

Aging of natural rubber blends containing 90 ° C stabilizing systems

Parameter 1 Stabilization system 4 5 2 3 residual tensile strength (%) 1 day 25 64 61 66 55 64 3 days 17 56 56 62 51 57 5 days 10 34 35 46 33 37

The practical use of the above-mentioned results is a mixed stabilizer in powder form and non-dust treatment, prepared by combining the stabilizers of bases I to III mentioned above, parts by weight 27 a-methylbenzylphenol 18 2-mercaptobenzimidazole 20 tris (a-methylbenzyl) phenylphosphite 35 hydrated silica Example 2

Chloroprene rubber vulcanizate according to the following formula by weight of chloroprene rubber, type WRT 100.0 stearic acid 0.5 magnesium oxide 4.0 zinc oxide 5.0 titanium dioxide 10.0 bright mineral filler 90.0 paraffin 3 Diethylene thiourea 1.0 2.2 ' -dibenzothiazole disulfide 0.5 and containing 2.0 parts by weight of stabilizer, when dosed on the active ingredient, was prepared by pressing to an optimum at 160 degrees Celsius.

Stabilizing system used 6. Stabilizing composition, the composition of which is given at the end of Example 1. 7. A stabilizer, consisting of 49 parts by weight of arelkylated phenol, 21 parts by weight of 2-mercap tobenzimidazole and 30% of inert carrier.

Retaining the vulcanization characteristics as for the unprotected mixture, the following properties of the vulcanizates were achieved.

Table 3

Properties of CR rubber vulcanizates after thermo-oxidative aging

Parameter Stabilization System - 6 7 Residual Elongation (%)

exposure 120 ° C 1 day 39 3 days 10 5 days 7 dynamic fatigue by de Mattia (kc) 3,2 7 days / 70 ° C (kc) 2,9 80 81 66 52 39 .28 14,4 8,1 8 The efficacy of the stabilizing system was evaluated based on the property of the vulcanizates of chloropropene rubber which exhibited the most pronounced ductility.

The vulcanizate containing the subject stabilizing composition, with the degree of coloration obtained after exposure to ultraviolet radiation, does not differ from that of unprotected vulcanizate.

Claims (1)

235194 7 8 ARTICLE A stabilizing composition for vulcanizates of natural and / or synthetic rubber base based on α-methylbenzylphenol and 2-mercapto-benzimidazole, characterized in that it comprises 25 to 40% by weight of tris (N-methylbenzylphenylphosphite of the general formula c and c). (I) wherein R is n-methylbenzyl and n is an integer of 1 to 3, 15 to 30% by weight of 2-mercaptobenzimidazole of formula II (II) and 30 to 60% by weight of α-methylbenzylphenol of formula III (lil) in which n is an integer from 1 to 3. Severografia, n. p "Plant 7, Most Price 2,40 Kčs