CS221000B1 - Method of stabilization of coloured vulcanizers from natural and synthetic rubbers against the thermooxidation ageing - Google Patents

Description

SOCIALIST REPUBLIC OF CZECHOSLOVAKIA (19) DESCRIPTION OF THE INVENTION OF THE CERTIFICATE OF AUTHORITY 221000 (11) (!) (51) Int. Cl.3 C 08 K 5/46 (22) Entries 09 09 61 C 09 K 15/26 Wi (21) (PV 66.34-81) (40) Zvelrejinemé 15 09 82 flftAD PRO í / YNAlEZY (45) Released 15 03 86 AND DISCOVERIES (75)

The inventor

HUMPLÍK ANTONÍN ing., GOGH TIBOR RNDr., ORLÍK IVO ing., KARVAŠ MILAN ing., CSc., MASEK JÁN ing., BRATISLAVA (54) The method of stabilization of color vulcanizates from natural and synthetic rubbers against thermo-oxidative aging 1

The present invention relates to the stabilization of color vulcanizates from natural and synthetic rubbers. It makes it possible to obtain vulcanizates with increased resistance to thermooxidation and, in addition, to improve the structural strength and ozone resistance. In the present invention, the addition of rubber compounds, when the semi-automatic weighing-in is still incomplete, does not substitute for human factors the high demands on the properties of the additive in terms of handling and environmental impact.

Increased demands on the efficacy of antioxidants entail the necessity of preparing higher molecular weight products. Such substances have the character of highly viscous liquids, such as, for example, substituted diphenyilamines, or tertiary alkylated phenyiazine derivatives, which are consistent with dosing problems. The products are needed to heat up at the current power consumption of the above. Usually they must be dosed manually.

These disadvantages are avoided by the method of stabilization. thermooxidative aging of natural and synthetic rubber colorants, characterized in that mixtures of phenothiazines formed by a compound of formula I 'n' - (T) '' V are used as stabilizers. "; 221600

221000 wherein if n = 1, the α-methylbenzyl group is at position 1, R 1 is hydrogen, or the α-methylbenzyl group is at polche 3 and R 1 is hydrogen or α-methylbenzyl; m = 21, .alpha.-methylbenzyl groups are in positions 1 and 3 and R @ 1 is hydrogen, in an amount of 0.5 to 5.0, preferably 1.5 to 3.0, by weight per 100. The parts of the phenothiazines are used in conjunction with conventional vulcanization accelerators such as N-cyclohexyilbenzothiazole-2-suilphenamide or tetramethylthiiramimonosulfide,

The phenothiazine mixture is composed of solid compounds such as 1α-methyl-benzylphenothiazine, 3-α-methylbenzyl-pheno-thiazine, 3 ', 7-di-α-methyl-benzyl-phenothiazine and 1,3-di-α-methyl-benzyl-benzothiazine. fenathiazine, wherein the first pair of compounds is 45: 55 to the other.

The use of the phenothiazines of the invention has many advantages. In view of the fact that it is a solid, the manageability is improved in the preparation of the raw mixtures for vulcanization, thus giving the possibility of half or full automatic weighing, eliminating the need for co-operation with the viscosity stabilizer and with it associated power consumption. As the product is in a non-dusty finish, the working environment's hygiene is essential.

As the phenothiazines substituted on the tert-methylbenzyl group exhibiting the antioxidant effects of the scoring derivatives used by diphenylamide or tertiary substituted phenothiazine derivatives, vulcanizates with increased resistance to thermo-oxidative aging are obtained by applying the phenothiazine-containing mixture of the invention. Navlecsa improves their structural strength and ozone resistance. The following are examples of practical examples of the invention as well as properties corresponding to their crude mixtures and vulcanisers.

These properties were monitored and evaluated by conventional tests in rubber and rubber technology.

The mixture of the phenothiazines themselves, optionally with other anti-degradants or antioxidants, is incorporated into the rubber composition by conventional processing methods such as lazy ingredients.

Thus, in a two-stage blend in a kneader machine, it can be added to the blend together with the activators, i.e., in stage I, or mixed into the mass of the crude rubber blend with a two-roll calender at a temperature of 50-70 ° C just prior to mixing the vulcanization system, ie in II. degree.

In one-stage mixing on a dual-roll calender, phenothiazine is added to the dry mixture after mixing all ingredients in accordance with the procedure described above.

After sufficient homogenization of the crude rubber mixture containing phenothiazine, the semi-finished product was rolled out on the two-roll calender for further processing. Example 1

Natural rubber vulcanizate according to the following recipe: natural rubber, 100 weight- 9MR-grade black carbon black, tuft HAF 35 weight-zinc oxide 3-part weight-stearic acid 3-parts weight-sulfur 2/25 parts-weight N- The cyclohexyl-2, 7-part parts by weight of the benzothiazole sulfene moiety of the amide and containing 3.0 parts by weight of anidegradant in each case were subjected to an increased temperature by the method according to GEER (CSN 62, 15 21). The aging process was observed by changes in the basic physical-mechanical properties (tensile strength, load, modulus of 300%, hardness and elasticity). The results are summarized in the tables: 221000 3 β

Table I,

Aging process of a vulcanizate containing 3.0 wt.% Of anti-degradant diet, monitored by decreasing the basic physico-mechanical properties of tensile strength and ductility, in hot air aging at 70 ° C: endpoint tensile strength 10 expressed% p. values 30 ductility 10 expressed% initially) 20 values 310 mixed-phenoxyphenate 2-, 2,4-aralkylated diphenylamine 4,4'-di-amylbenzyl diphenylamine 100 antidegradant 100 90 99 94 91 88 82 08 74 96 95 99 '84 180 81 74 08 '09

The vulcanization characteristics of the crude mixtures, monitored by the MON-SANTO method at 145 ° C, as well as the physico-mechanical properties of the vulcanizates obtained by pressing the aforementioned mixtures to an optimum at 145 ° C are comparable.

Table II. observed antidegradant mixed 2-, and 2,4-arylalkylo-4,4‘-di-α-methyl-phenothiazine vine diphenylamine benzyl diphenyl amine parameter

Vulcanization Characteristics MONSANTO 11415 ° G —tbi (min) 7.5 6.0 6.0 —v90 (min) 17.25 16.25 16.25 —RV (min-1) 0.75 9.75 9.75

Physical-mechanical properties of vulcanizates vv9o / l40) ° C modulus 200% (MPa) 3,02 3,56 l3, i30 tensile strength (MPa) 27,7 030,0 25,3 22,0 'ductility (%) hardness 575 , 0 550,0 (IRHD) 54,0 03,0 51,0 Elasticity (;%) Structural 51,0 54,0 50, (0 Strength (Nm-1) 08,0 384 36,9 1 ad 2 * Acid 1,5 weight stearic parts Mixed phenoxythiazine, substituted on the nuclei with an α-methylenyl group, added in sulfur 2.0 by weight 1.5 parts by weight of the mixture of the recipe: tetramethylthiur 0.5 wt. native rubber, 10% by weight monosulphide parts SMR-L parts also protect the vulcanizate against elevated temperatures © o - a mixture of barium sulphate - 80% by weight more effective © as the liquid types of ahtideg and sulfuric zinc radium (70:30) ) (Aging process of vulcanizates, 15 wt.% Oxide monitored, and due to the decrease in ductility, aging of the zinc components) at 100 ° C.

Claims (1)

221000 Table III. monitoredparameter number of days mixed phenothiazine 2-, 2,4-araliphatic diphenyilamin 4,4‘-di-α-methylibenzyl diphenylamine ductility 2 89 88 90 ex. in% 4 63 51 54 Flood 6 39 29 33 Values 9 27 18 19 Example 3 Zinc Oxide 3% by weight Mixed phenothiazine, substituted by α-methyl-benzyl group, and core, added in 1.75 weight-sulfur concentration, 2 5 parts by weight of the mixture according to the formula: N-cyclohexyl-2-l-butadiene-styrene -benzothiazole-sudenene-lime rubber amide type 1.501 (e.g. 100 weight-antioxidant 2.25 weight-Kralex 010.4101) which affects the aging, the monitored bedding, the HAF 50 type of tensile strength depending on the aging parts in the hot air at the temperature of IliO ° C (method according to GEERaj, captures stearic acid 1 weight- following the table exceeds the effective liquid types used in the table: Table IV: Mixed 2-, 2,4-aral-4,4'-a-me- day parameters phenothiazine tylbenzyl diphenylamine diphenyliamine tensile strength u 1 102 94 9Q expressed 3 91 81 63% original 5 85 75 7® values 9 812 71 71 OBJECTS DISCONTINUED The method of stabilizing color vulcanisers from natural and synthetic rubber against thermo-oxidative aging, characterized in that phenothiazine is used as stabilizer formed by the compounds of formula I (I) 221000 10 wherein when n = 1, the methylbenzyl group is at the 1-position and R is hydrogen, or the N-methylbenzyl group at the 3-position and R is hydrogen or a-methylbenzyl; when n = 2, the α-methylbenzyl groups are in positions 1 and 3 and R is hydrogen in an amount of 0.5 to 5.0, preferably 1.5 to 3.0 parts by weight per 100 weight parts of elastomer , optionally together with conventional vulcanization accelerators, such as N-cyclohexyl-2-benzitiaaol sulfenamide, or tetramethylthiurammonio sulfide.