CS277646B6 - N,n'-substituted bis-(2,4-diamino-s-triazin-6-yl)oligosulfides - Google Patents

Abstract

Compounds of the general formula <IMAGE> in which R<1>, R<2> denote H; R<2> denotes benzyl, R<2>, R<3>, R<4> denote C1-C8-alkyl, allyl, C3-C8-cycloalkyl, the latter being unsubstituted or substituted by 1-3 methyl groups, 2-hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl or R<3> and R<4> (together) denote C4-C6-alkylene, -(CH2-CHX)2Y where X is H, CH3 and Y is O, S and their oligosulphide disproportionation products, whose average statistical chain length corresponds to S4 are prepared from the corresponding N,N'-substituted diaminomercaptotriazines. The substances according to the invention are used in vulcanisable rubber mixtures as crosslinking agents without sulphur or as vulcanisation accelerators together with sulphur.

Description

Technical field

The invention relates to Ν, Ν-substituted bis- (2,4-diamino-striazin-6-yl) oligosulfides, processes for their preparation, their use as crosslinkers and vulcanization accelerators, and rubber mixtures containing these compounds. The compounds of the invention improve the vulcanization behavior of the rubber compositions and impart improved properties to the vulcanizates made from these compositions.

BACKGROUND OF THE INVENTION

Ν, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) disulfides are known and are described in DE Patent No. 1 699 954. They are made from the corresponding N, N'-substituted 2 &apos; 4-diamino-6-mercaptotriazines by oxidation such as iodine, sodium hypochlorite or hydrogen peroxide. The best known compound in this group is bis- (2-ethylamino-4-diethylaminotriazin-6-yl) disulfide. Disulfides of this group can be used in rubber mixtures as accelerators.

CS Patent No. 276,589 discloses tetrasulfides of Formula I

R ¹ represents a hydrogen atom, o "

R ⁴ is hydrogen or benzyl and each of R ² , R ³ and R ⁴ is C 1 -C 8 alkyl, preferably C 1 -C 4, which is branched or unbranched; allyl, C 3 -C 8 cycloalkyl optionally substituted with 1 to 3 methyl groups; 2-hydroxyethyl; 3-hydroxypropyl; Or 2-hydroxypropyl;

R ³ and R ⁴ together represent an alkylene group having 4 to 6 carbon atoms or a group of the formula wherein

- (ch ₂ -chx) ₂ y,

X is methyl or hydrogen; and

Y represents oxygen or sulfur.

These tetrasulfide was produced by an aqueous alkaline solution of the corresponding Ν, Ν'-substituted 2,4-diamino-6-mercaptotriazine is reacted in a two phase system with a solution of sulfur monochloride (S2C1 ₂₎ in an inert organic solvent in which the reaction insoluble or sparingly soluble product, at a temperature in the range of -5 ° C to <20 ° C, preferably at 10 ° C.

Preferably, an alkaline aqueous solution of mercaptotriazine is used which contains the alkali hydroxide in at least a stoichiometric amount relative to the reactions. Preferably, the alkaline solution contains an excess of alkaline hydroxide of 1 to 20 mol%, based on the mercaptotriazine used.

This solution is mixed with a solvent in which the end product of the reaction is insoluble or sparingly soluble, preferably with C 5 -C 10 alkanes or C 5 -C 8 cycloalkanes optionally substituted with 1 to 3 methyl groups, or mixtures thereof. The resulting mixture is vigorously stirred and cooled, preferably to + 10 ° C and sulfuric chloride (S ₂ Cl ₂ ) in the solvent used is added dropwise while cooling.

The sulfur trichloride is used at a ratio of at least 2 moles of mercaptotriazine per mole of sulfur trichloride, depending on the excess of alkali, but this ratio may also be 2: 1.1 to 1.2.

Under these conditions, sulfur trichloride (S ₂ Cl ₂ ) is exclusively condensing.

The blast product is separated by a known method and is preferably dried at a temperature of up to 50 ° C under vacuum.

The present invention relates to a process for the preparation of oligosulfides of the general formula II. ?. ⁴ ??

X..X \, X where \ -2

R ¹ , R ² , R ³ and R ⁴ are as defined above and

S _x represents a sulfur chain with a mean statistical length corresponding to n = 4.

These oligosulfide mixtures, also referred to hereinafter as disproportionates, as they are prepared by disproportionation of the tetrasulfides of formula (I), can be prepared by various methods.

The reaction conditions must be controlled in such a way that no free sulfur is formed.

One method is characterized in that the isolated tetrasulfide of formula (II) is heated above its melting point, preferably by 20 to 50 ° C.

According to another method, the tetrasulfide of formula II is dissolved in an inert organic solvent and disproportionate

the reaction is carried out at a temperature ranging from 20 ° C (the solution is allowed to stand at room temperature) to the boiling point of the solvent used.

A particularly elegant method is to react an aqueous alkaline solution of the corresponding Ν, Ν-substituted 2,4-diamino-6-mercaptotriazines in a two-phase system with a solution of sulfur trichloride in an inert organic solvent in which the tetrasulfide formed is soluble. The resulting linear tetrasulfide then immediately disproportionates to the composition of the invention.

Suitable solvents are, in particular, chlorinated hydrocarbons, for example methylene chloride or chloroform, but ethers, esters, aromatic hydrocarbons and ketones are also suitable for the disproportionation reaction in the absence of water. Alternatively, they can be used to form a two-phase mixture with water. The reaction conditions for the production of disproportionates are otherwise the same as those for the preparation of pure tetrasulfide.

The above-defined oligosulfides, i.e. the tetrasulfide disproportionates prepared according to the invention, have a similar effect to the corresponding tetrasulfides and as crosslinkers or vulcanization accelerators significantly exceed the standard compounds currently used.

The rubber industry has a wide variety of accelerators at its disposal (J. van Alphen, Rubber Chemicals (1977, pp. 1 to 46)), mainly used for sulfur vulcanization, for example benzthiazolylsulfonamides, benzthiazolyl disulfide and 2-mercaptobenzthiazole or zinc salts thereof. In addition, there are a number of special compounds, such as thiuram disulfides and peroxides, which act as crosslinkers even without the addition of sulfur, but are often used as accelerators in combination with sulfur. The method of use depends on the effect to be achieved in each case.

Benzthiazolylsulfenamides are currently of great importance in practical applications, including in particular the acceleration of vulcanization of elastomers.

Due to new manufacturing processes, new products and constant pressure on rationalization, the demands placed on accelerators have recently changed to such an extent that it can now be difficult to meet the qualitative requirements for the vulcanization process and vulcanizate properties using accelerators or crosslinking agents. which are currently available for accelerated sulfur vulcanization.

Another disadvantage of some conventional accelerators (for example some sulfenamides and thiurams) is that they can release amines during the vulcanization process which, if nitrosatable, lead to the formation of nitrosamines in the vulcanizate. If these accelerators lead to the formation of toxic nitrosamines, the potential for their application can be expected to decrease over time.

A major disadvantage of benzthiazolyl accelerators, especially benzthiazolylsulfenamides, is their tendency to reverse, which is becoming more pronounced with increasing vulcanization temperature with often inevitable overheating of the vulcanizates, in particular using types of rubber which are no longer prone to reversion such as natural rubber. and polyisoprene and mixtures thereof with synthetic rubbers. However, the situation is similar for synthetic rubbers of all kinds, unless the reverse process is covered by thermal sieving. Especially as the vulcanization temperature rises, the reversal rate increases so strongly that, firstly, even with optimum vulcanization, there is a noticeable decrease in crosslinking density; secondly, vulcanization optimum takes the form of peaks instead of plateau, making it extremely difficult to reproduce retention of optimal vulcanizate properties; , in many cases the re-vulcanization required leads to a decrease in the crosslinking density which cannot be avoided, which leads, in particular in the case of thick-walled rubber products, to the cross-linking of the vulcanizate not being uniform. As much as the reversal increases, the properties of the vulcanizate, such as the modulus at 300% elongation or abrasion resistance, deteriorate.

To some extent, it leads. reducing the proportion of sulfur and increasing the proportion of accelerator, i.e. the use of so-called Semi-EV systems (L. Bateman, 1963, The Chemistry and Physics of Rubber-Like Substances, pp. 522 et seq.), to alleviate said reverse effects. However, attenuation of this reversion is achieved through a change in the structure of the crosslinking (-S 4 -, -S-S- and -S- bonds) in favor of monosulfide crosslinking. structures, which may adversely affect the properties of the vulcanizate. This measure, however, is the less effective the higher the vulcanization temperature is.

These disadvantages of benzthiazole accelerators limit their applicability at increasing temperatures and to some extent limit the effort of the rubber industry to increase productivity using higher vulcanization temperatures.

Surprisingly, it has been found that the disproportionation products of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides prepared by the process of the invention are compounds which, when used as accelerators in sulfur vulcanization, thus, when used as crosslinkers, i.e. without the addition of sulfur, they impart an extremely high reverse stability even at very high overheating, even at high vulcanization temperatures. The otherwise customary reverse process using them either does not occur at all or to a small extent. In fact, the surprising fact that the cross-linking structures formed using the disproportionation products of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides of the formula II is exceptionally reversible and thermally stable results in their use in rubber mixtures even at high vulcanization temperatures to achieve a high level of physical-mechanical properties of the vulcanizate after completion of the cross-linking reaction and, on the other hand, to maintain a high level of physical-mechanical properties for a long time.

Together, these effects make it possible to increase productivity in the rubber industry by increasing the vulcanization temperature without causing loss of performance properties of the vulcanizate.

Not even approximately the same reverse stability can be achieved with commercially available polysulfides such as Robac ^R P 25 (Robinson, dipentamethylenethiurametetrasulfide) and Tetron ^R A (Du Pont, dipentamethylenethiuramhexasulfide) or with dibenzthiazolyltetrasulfide.

The disproportionation products of N, N'-substituted bis- (2,4-diamono-s-triazin-6-yl) tetrasulfides prepared according to the invention are suitable for prior art rubber mixtures containing natural rubber (NR), isoprene rubbers (IR ), butadiene rubbers (BR), styrene-butadiene rubbers (SBR), isobutylene-isoprene rubbers (IIR), ethylene-propylene terpolymers (EPDM), nitrile rubbers (NBR), halogen-containing rubbers, as well as epoxidized natural rubbers (ENR) . Of particular importance is the use of the disproportionation products of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides prepared according to the invention for those types of rubber which tend to be reversed, such as natural rubber , isoprene and butadiene rubbers and mixtures thereof or mixtures thereof with other rubbers.

The disproportionation products of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides prepared according to the invention are used as crosslinkers in rubber mixtures in an amount of 0.2 to 15 parts by weight, preferably 0.3 up to 8 parts by weight per 100 parts by weight of rubber.

In accelerated sulfur vulcanization, the disproportionation products of the N, Ν'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides prepared according to the invention are used as accelerators in an amount of 0.01 to 10, and preferably 0, 1 to 5 parts by weight per 100 parts by weight of rubber at a sulfur dosage of 0.1 to 10 parts by weight.

Preferably, the molar ratio of accelerator to sulfur according to the invention, (S ₈₎ is in the range from 1: 0.5 to 1.5. To extend the possibilities of variation in the vulcanization kinetics, it may be effective to use two or more of the N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides prepared according to the invention in a mixture of disproportionation products while maintaining the above these amounts, in particular the preferred accelerator / sulfur ratio, need to be replaced by one on a molar basis. The same applies to the use of the disproportionation products N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides prepared according to the invention as crosslinkers in the absence of sulfur.

Also, for reasons of kinetics, it may be useful to use the disproportionation products of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides in admixture with conventional accelerators, for example sulfenamides and thiurams. These measures are sometimes due to reverse stability compared to vulcanizates whose vulcanization has been accelerated using the disproportionation products of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides prepared according to the invention alone. Conversely, the reverse behavior of the vulcanizates may have a positive effect when the disproportionation products of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides obtainable by the process of the invention are used instead of a portion of conventional accelerators.

Further substantial influence on the incubation time can be achieved by using the compounds prepared according to the invention in rubber mixtures by combining them with commercially available vulcanization retardants such as Santoguard ^R PVI (N-cyclohexylthio) phthalimide) and ^R E (N-phenyl-N-trichloromethylsulfenyl) benzenesulfonamide ). Vulkalent ^R E from p

Bayer AG. As the addition of Vulcalent E increases, the incubation time of the mixture containing disproportionates of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides is linearly increased.

When using the disproportionation products of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides as cross-linkers, it has proved useful to maintain the molar ratio of pr, N'-substituted bis- (2, 4-diamino-s-triazin-6-yl) tetrasulfides to vulcanent E at 1: 0.5 to 1.5, preferably 1: 0.8 to 1.2 parts by weight per 100 parts by weight of rubber.

More important is the use of retarders, particularly Vulcalent E, in accelerated sulfur vulcanization using N, N'-substituted disproportionates; bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides or mixtures thereof. A slight decrease in the crosslinking rate is sometimes observed in addition to the intended incubation time of the crosslinking reaction, but this can be compensated by an increase in temperature and a slight decrease in reverse stability. In this case, the molar ratio of the disproportionation products of the Ν, Ν'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides obtainable according to the invention to Vulcalent E was also found to be 1: 0.5. to 1.5, preferably 1: 0.8 to 1.2, wherein the sulfur content is maintained between 0.1 and 10, preferably 0.5 to 8 parts by weight, based on 100 parts by weight of rubber, depending on the type of mixture.

Using the recommended dosage, many of these vulcanization problems can be solved without at the same time substantially deteriorating the properties of the vulcanizate that is foreign to the present invention.

Mixtures containing only silicic acid or a mixture of carbon black and silicic acid with a proportion of silicic acid greater than 15 parts per 100 parts of rubber are difficult to crosslink with conventional sulfur-based vulcanization systems, if such crosslinking is even feasible. On the one hand, they are particularly reversed and, on the other hand, it is impossible to set the cross-linking density to a predetermined value for the finished product. This is one of the reasons why silicas are preferably used in soles, but so far rarely in dynamically stressed products.

Surprisingly, using the disproportionation products of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides obtainable according to the invention, mixtures containing black and white mixtures in which the proportion of silicic acid is more than 15 parts per 100 parts of rubber, and also for silica-filled compositions, virtually eliminating the reverse while increasing the crosslink density, which in silica-containing compositions exhibits a high level of stress for silica-containing compositions. This effect is achieved when the compounds of the invention are used as both accelerators and crosslinkers (without sulfur).

Another possibility of using the disproportionation products of N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides obtainable according to the invention lies in their combined application with oligosulfide organosilanes, for example by compounds of the general formulas [(RO) ₃ Si - (CH ₂ ) _n ] ₂ · ^s x or (RO) ₃ -Si- (CH ₂ ) _n -SH, where n is 2 or 3, x is 2 to 6, and

R is C 1 -C 6 alkyl; . cyclohexyl • CH3.

x is from 2 to 6, preferably 3 and

R is methyl or ethyl, preferably with bis- (3-triethoxysilylpropyl) tetrasulfide (Si 69, Degussa AG). The disproportionation products of the N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides obtainable according to the invention can advantageously be used both in the organosilane crosslinking in the absence of sulfur instead of the accelerators described in DE patent No. 25 36 674, as well as in sulfur vulcanization in the presence of organosilanes according to DE Patent No. 2,255,577 and also in the production of reverse stable organosilane-containing rubber compositions, by constructing equilibrium curing systems according to DE patent

No. 2,848,559.

This applies to both carbon black-filled mixtures and mixtures containing mixtures of carbon black and silicic acid, as well as mixtures made using only silicic acid. Also, the addition of mineral fillers does not adversely affect any of the above mixtures.

In the presence of silica-based fillers or mixtures of carbon black and silicic acid, rubber / filler bonds are formed (Kautschuk + Gummi, Kunststoffe, Vol. 8, 1977, pp. 516-523, Vol. 10, 1979, pp. 760-765 and Vol. 4, 1981, pp. 280-284) or, in the case of carbon black, rubber-rubber bonds.

The formation of rubber / rubber crosslinking sites in the presence of carbon black, or rubber / filler crosslinking sites, in the presence of silicic acid, or both, in the case of mixtures of carbon black and silicic acid in all ratios, occurs when disproportionation products N, N ' -substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides obtainable according to the invention are used alone or in admixture with or with a mixture of conventional accelerators together with conventional sulfur donors such as Sulfasan ^R R ( morpholinedisulfide).

The compounds obtainable according to the invention are used in rubber compositions which may contain other conventional components, such as, for example

- conventional reinforcing systems, ie retort aze, gas black, lamp black, thermal black, acetylene black, arc black, CK black, etc., as well as synthetic fillers such as silicas, silicates, hydrates · oxide aluminum, various types of calcium carbonate and natural fillers such as clays, siliceous chalks, chalks, talc, etc., and silane-modified fillers and mixtures thereof in an amount of 5 to 300 parts per 100 parts of rubber, especially silicas and silicates;

zinc oxide and stearic acid as vulcanization promoters in amounts of 0.5 to 10 parts per 100 parts of rubber; commonly used antioxidants, antiozonants and anti-fatigue agents such as IPPD, TMQ etc. as well as waxes as light stabilizers and mixtures thereof;

- any emollients such as aromatic, naphthenic, paraffinic or synthetic emollients and mixtures thereof;

optionally other silanes such as (1-chloropropyl) trialkoxysilanes, vinyltrialkoxysilanes and aminoalkyltrialkoxysilanes, and mixtures thereof in an amount of 0.1 to 15, preferably 1 to 10 parts per 100 parts of fillers containing silanol groups such as silicas, silicates, clays , etc .;

- colorants and processing aids, if any, in the usual dosage.

The range of applications in which rubber mixtures containing disproportionation products can be used

N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides include use in the manufacture of tires, in the manufacture of technical products such as conveyor belts, V-belts, wrought products, hoses with or without liner of rubber, rolled rubber products, linings, injection molded profiles, foils, bottoms and uppers of shoes, cables and solid rubber tires.

Examples of oligosulfides of formula II include the following products:

K bis- (2-isopropylamino-4-diisopropylamino-s-triazin-6-yl) oligosulfide mixture

L bis- (2-cyclohexylamino-4-diethylamino-s-triazin-6-yl) oligosulfide mixture

M bis- (2-ethylamino-4-diethylamino-s-triazin-6-yl) oligosulfide mixture bis- (2-amino-4-diethylamino-s-triazin-6-yl) oligosulfide mixture.

Example 1

454 g of 2-ethylamino-4-diethylamino-6-mercaptotriazine are dissolved in a sodium hydroxide solution prepared from 84 g of sodium hydroxide and 1.5 liters of water.

Place the solution in a 4 liter three-necked flask, add to it 1,5 liters of light petrol (boiling point 80 to 110 ° C) and cool to 0 ° C with vigorous stirring.

137 g of sulfur trichloride (S ₂ Cl ₂ ) in 100 ml of petrol are added to the mixture over 20 minutes, taking care that the temperature does not exceed + 5 ° C.

Tetrasulfide is precipitated immediately. After completion of the reaction, the mixture was stirred for a further five minutes and then the product was filtered off and washed.

The fine snow-white powder is dried at 40-45 ° C under vacuum, 50 mmHg.

Yield: 499.5 g (97.1% of theory);

Analysis:

bis- (2-ethylamino-4-diethylamino-s-triazin-6-yl) tetrasulfide, molecular weight 516, for ^C 32 ^H i8 ^{10 N} 4: calculated: 41.9% C, 6.2% H, 27 1% N, 24.8% S;

Found: C 41.8%, H 6.5%, N 26.8%, S. 24.8%.

TLC and HPLC analysis indicated that the product contained 97.1% linear tetrasulfides.

Example 2

45.4 g of 2-ethylamino-4-diethylamino-6-mercaptotriazine are dissolved in a sodium hydroxide solution prepared by dissolution

8.8 g of sodium hydroxide in 200 ml of water. 200 ml of methylene chloride are added. The mixture was cooled to 0 ° C with stirring with a turbine stirrer. 14 g of sulfur trichloride (S ₂ Cl ₂ ) are dissolved in 50 ml of methylene chloride and the resulting solution is added to the mercaptide solution.

The reaction product was dissolved in methylene chloride. After completion of the reaction, the phases were separated and the methylene chloride solution was worked up.

This gives an amorphous powder with a softening point of about 110 ° C.

Yield: 46.7 g, corresponding to 90.5% of theory.

Analysis: for C ₁₈ H ₃₂ N ₁₀ S ₄ (molecular weight 516): calculated: 27.1% N 24.8% S;

found: 26.8% N, 24.4% S.

According to TLC analysis, the mixture contains 4 oligosulfides but no free sulfur.

Example 3

50. g of bis- (2-ethylamino-4-diethylamino-s-triazin-6-yl) tetrasulfide of 97.1% purity was placed in a round bottom flask and heated in an oil bath at 160 ° C for 1 hour. After cooling, the melt solidifies to an amorphous substance. According to TLC analysis, the product contains three additional oligosulfides in addition to 50% of the starting product.

Example 4

70.25 g of 2-cyclohexylamino-4-diethylamino-6-mercaptotriazine are dissolved in a solution of 11 g of sodium hydroxide in 250 ml of water and 250 ml of chloroform are added. With vigorous stirring, a solution of 16.8 g of sulfur trichloride (S ₂ Cl ₂ ) in 30 ml of chloroform is added. After completion of the reaction, the phases were separated and the chloroform layer was worked up. 71.9 g of white amorphous powder are obtained, corresponding to 92% of theory.

Analysis: Calculated for C ₂₆ H ₄₄ N ₁₀ S ₄ (MW 624): C 50.0%, H 7.05%, N 22.4%, S 20.51%; Found: C, 49.1; H, 90.90; N, 21.8; S, 20.0.

According to TLC analysis, the product consists of about 30% linear S ₄ -product and 70% oligosulfides but does not contain any free sulfur.

Test standards

Testing of physical properties is carried out in a room according to the following standards:

at temperature tensile strength, ductility and stress value on 6 mm thick rings Shore A hardness A Firestone-Ball Rebound reversal incubation time ti vulcanization time standard DIN 53504

DIN 53505 AD 20245

DE patent 2848559 DIN 53529 ASTM D 2084 units MPa min min

Application examples use names and abbreviations that have the following meaning:

RSS: Ribbed Smoked Sheet (Natural Rubber)

CORAx ( ^R ) N 220: soot, surface area (BET) 120 m ² / g (Degussa)

11,

Naftolen ZD: hydrocarbon softener Ingraplast ^R NS: naphthenic hydrocarbon softener Vulkanox 4010 NA: N-isopropyl-N'-phenyl-p-phenylenediamine Vulkanox ^(R) HS: poly-2,2,4-trimethyl-1,2-dihydroquinoline Mesamoll ( ^R ) an alkylsulfonic acid ester of phenol and cresol Robac P 25: dipentamethylenethiuramtetrasulfide Tetrone-A: dipentamethylenethiuramhexasulf id Protector ( ^R ) G 35: antiozonant wax Vulcacite ( ^R ) MOZ: benzthiazolyl-2-morpholinosulfenamide Vulcacite ( ^R ) Mercapto: 2-mercaptobenzthiazole Vulcacite ( ^R ) Thiuram: tetramethylthiurammonosulf id Vulcacite ( ^R ) CZ: · N-cyclohexyl-2-benzothiazolesulfenamide Vulkalent ^(R) E: N-phenyl-N- (trichloromethylsulfenyl) benzenesulfonamide PVI: N-cyclohexylthiophthalimide Ultrasil ^(R) VN 3:  precipitated silica (DegussaJ grain.: granulate V 143: bis- (2-ethylamino-4-diethylamino-s-triazin-6-yl) disulfide Vulcacit ( ^R ) NZ: benzothiazyl-2-tert-butylsulfenamide

Example 5

Reverse stability of NR mixtures filled with N 220, cross-linked using classical systems

Mix No. 1 2

RSS 1, ML4 = 70-80 100 ALIGN! 100 ALIGN! CORAX N 220 50 50 ZnO RS 5 5 stearic acid 2 2 Naftolen ZD 3 3 Vukanox 4010 NA 2.5 2.5 Vulkanox HS 1.5 1.5 Protector G 35 1 1 Vulkacit MOZ 1.43 - V 143 - 1.29 Santoguard PVI - 0.4 sulfur 1.5 1.5

Reverse:

^D max ” ^D (max + 60 ⁾ ) ^D max“ ^D min at a vulcanization temperature of 170 ° C

30.1

8.6

Reverse stability of NR mixtures crosslinked with Ν, Ν'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides (without sulfur) filled with N220

Mixture number

RSS 1, ML 4 = 70-80 100

Corax N 220

ZnO RS 5 stearic acid 2

Naphtholene ZD 3

Vulkanox 4010 NA 2.5

Vulkanox HS 1.5

Protector G 35 1

K. '····'. ·· '3.84

L

M

100 ALIGN!

2.5

1.5 1

3.62

100 ALIGN!

2.5

1.5 1

4.0

Reverse:

^D max ^D (max + 60 *) * ^D max ^D min at vulcanization temperature 170

2.5 ° C.

3.1

2.3

When used as sulfur-free crosslinking agents, the Ν, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides of the invention impart exceptional reverse stability to carbon black-filled NR (mixtures 5-7) in compared to a mixture containing the semi-EV system (mixture 1) or a mixture containing bis- (2-ethyl-amino-4-diethylamine-s-triazin-6-yl) disulfide (V 143) (mixture 2).

Example 6

Reverse stability of NR-mixture filled with N220 silica and cross-linked with a semi-EV system

Mixture number 8

RSS 1, ML (1 + 4 = 70 - 80) 100

Corax N 220

Ultrasil VP 3 gran. 25

ZnO RS 5 stearic acid 2

Naphtholene ZD 3

Vulkanox 4010 NA 2.5

Vulkanox HS 1.5

Protector G 35 1

Vulkacit MOZ 1,43 sulfur 1,5

Reverse:

^D max ^D (max + 60 ') ^{% D} max ” ^D min at vulcanization temperature 170

47.1 ° C.

Reverse stability of NR-mixture filled with N220 silica and cross-linked with Ν, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides (without sulfur)

Mixture number 13 14 15 Dec RSS 1, ML (1 + 4) = 70-80 100 ALIGN! 100 ALIGN! 100 · CORAX N 220 25 25 25 Ultrasil VP 3 gran. 25 25 25 ZnO RS 5 5 5 stearic acid ^; 2 2 2 Naftolen ZD 3 3 3 Vulkanox 4010 NA 2.5 2.5 2.5 Vulkanox HS 1.5 1.5 1.5 Protector G 35 1 1 1 K. 3.48 T- - L - 3.62 - M - - 3.0 Reverse: ^D max ^-D (max + 60 ^{) D} max “ ^D min 2.5 3.1 4.7

at a vulcanization temperature of 170 ’C.

NR-mixtures containing silicic acid also show strong reverse effects even with semi-EV systems (mixture no. 8). When Ν, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides (mixtures No. 13 to 15) are used as the crosslinker according to the invention, an almost complete suppression is achieved with otherwise identical composition of the mixtures reversing.

Example 7

Reverse resistance of NR-compound filled with N220 and accelerated

Vulkacitem MOZ

Mixture number 16

RSS 1, ML (1 + 4) = 70-80 100 CORAX N 220 50 ZnO RS 5 stearic acid 2

Naftolen ZD 3 Vulkanox 4010 NA 2.5 Vulkanox HS 1.5 Protector G 35 1 Vulkacit MOZ 1.43 sulfur 1.5 ^D max “ ^D (max + 60 ⁾ ) * D -D · 31.9 max ^u mm at a vulcanization temperature of 170 Deň: 32 ° C. Properties of vulcanizate at 170 ° C, m.p. 95% tensile strength 23.0 voltage at 300% elongation 9.6 NR- Reverse Area -mix filled with N220 and accelerated Ν, N'-disubstituted bis- (2,4-diamino-s-triazine-6- -yl) oligosulfides Mixture number. 25 26 27 Mar: RSS 1, ML (1 + 4) = 70-80 100 ALIGN! 100 ALIGN! 100 ALIGN! CORAX N 220 50 50 50 ZnO RS 5 5 5 stearic acid 2 2 2 Naftolen ZD 3 3 3 Vulkanox 4010 NA 2,5 ' 2.5 2.5 Vulkanox HS 1.5 1.5 1.5 Protector G 35 1 1 1 TO 1.74 - - L - 1.81 - M - - 1.5 sulfur 0.8 0.8 0.8 Reverse: ^D max “ ^D (max + 6o ') * ^D max “ ^D min 0.4 1.5 5.2 at a vulcanization temperature of 170 Deň: 32 ° C. Properties of vulcanizate at 170 ° C, t 95% tensile strength 22.9 24.2 22.2 voltage at 300% elongation 10.3 10.0 10.6

At equimolar dosing of the accelerator, the amount of sulfur can be reduced for N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides. However, a higher stress value is achieved at 300% elongation. Mixtures made using N, N'-disubstituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides (mixtures 25 to 27) are exceptionally reverse stable compared to mixtures containing the semi-EV system (mixture No. 16).

Example 8

Comparison of the reverse behavior of commercially available oligosulfides and dibenzthiazolyltetrasulfide versus

Ν, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfide in NR-mixtures filled with N220

Mixture number 30 31 32 33

RSS 1, ML (1 + 4) = 70-80 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! CORAX N 220 50 50 50 50 ZnO RS 5 5 5 5 stearic acid 2 2. 2 2 Naftolen ZD 3 3 3 3 Vulkanox 4010 NA 2.5 2.5 2.5 2.5 Vulkanox HS 1.5 1.5 1.5 1.5 Protector G 35 1 1 1 1 Robac P 25 1.12 - - - Tetrone A - 1.3 - - dibenzthiazolyltetra- sulphide - - 1.15 - M - - -  1.5 sulfur · '' 0.8 0.8 0.8 0.8 vulcanizing time of the mixture at 170 ° C (t 10%), min 1.4 1.9 2.7 3.1 Reverse:. ^D max ” ^D (max + 6o ') ^D max ^-D min 18.5 21.3 35.7 3.2

at a vulcanization temperature of 170 C.

Properties of vulcanizate at 170 ’C, t 95% tensile strength 23.1 21.2 18.9 23.6 voltage at 300% elongation 9.4 9.5 7.3 10.4

Commercially available oligosulfides (mixtures 30 and 31), as well as dibenzthiazolyltetrasulfide (mixture 32), have several times higher reversal in the NR mixtures than N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) ) oligosulfide (mixture 33).

Example 9

Mixture of Ν,''-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfide and Ν, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfide in NS-mixtures filled with N 220

Mixture number 45 46 47 48 RSS 1, ML (1 + 4) = 70-80 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! CORAX N 220 50 50 50 50 ZnO RS 5 5 5 5

stearic acid 2 Naftolen ZD 3 Vulkanox 4010 NA 2.5 Vulkanox HS 1.5 Protector G 35 1 Vulkacit MOZ 1.43 M - (B) - sulfur 1.5

Reverse:

2 2 2 3 3 3 2.5 2.5 2.5 1.5 1.5 1.5 1 1 1 - - - 1.5 - 0.75 - 1.66 0.83 0.8 0.8 0.8

^D max Pax + eo ¹ )

2.3 0.4 1.2

Note: B = bis- (2-n-butylamino-4-diethylamino-s-triazin-6-yl) tetrasulfide

When profilu, Ν'-substituted bis- (2,4-diamino-s-triazin-6-yl) tetrasulfides are used together with different reverse stability, a value profile is found which is between the values for pure substances (mixture 48). · - '

Example 10

N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides in SBR-mixtures filled with N 220

Mixture number 51 54 55

SBR 1500

CORAX N 220 ZnO RS Stearic acid Naftolene ZD Protector G 35 Vulkanox 4010 NA Vulkanox HS Portector G 35 Vulcacit MOZ K

M sulfur

100 ALIGN! 100 ALIGN! 100 ALIGN! 50 50 50 5. 5 5 2 2 2 3 3 3 1 1 1 2.5 2.5 2.5 1.5 1.5 1.5 1 1 1 1.43 - - - 1.5 - - - 1.5 1.5 1.5 1.5

Reverse:

^D max ~ ^D (max + 60 ^L )% ^D max ^_D min at a vulcanization temperature of 170

Properties of vulcanizate at 170 ´C, t 95% tensile strength

12.9 9.2 12.5 ° C.

20,6 20,5 19,9 stress at 300% elongation 10,0 12,1 12,3 elongation 460 420 390 Shore hardness 61 63 64

At the same sulfur dosage, N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides (mixtures 54 and 55) in SBR 1500 exhibit a significantly higher voltage value and slightly improved reverse properties over conventional acceleration (mixture 51). ·

Example 11

Ν, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides in a mixture of isoprene rubber filled with N 220

Mixture number 56 58 59 polyisoprene 3.4 100 ALIGN! 100 ALIGN! 100 ALIGN! CORAX N 220 50 50 50 ZnO RS 5 5 5 stearic acid 2 2 2 Naftolen ZD 3 3 3 Vulkanox 4010 NA 2.5 2.5 2.5 Vulkanox HS ^ζ Λ 1.5 1.5 1.5 Portector G 35 1 1 1 Vulkacit MOZ 1.43 - - L - 1.6 - M - - 1.5 sulfur. . ^{Χ '5} 0.8 0.8 Reverse: ^D max ^"D (max + ^{60)% D} max ^-D min 21.0 0.0 0.0 at a vulcanization temperature of 170 'C. Properties of vulcanizate at 170 ° C, voltage at 300% elongation, t 95% 7.9 6.3 6.4 t 95% + 80 ' 6.2 6.3 ⁷ , 1 Even with polyisoprene rubber reaches beyond use N, N

-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides (mixtures 58 and 59) significantly improved the reversal compared to the mixture containing the conventional accelerator (mixture 56). This improvement is also manifested in the stability of the vulcanizate properties with considerable overheating.

Example 12

Ν, N'-substituted bis- (2,4-diaminotriazin-6-yl) oligosulfides in EPDM mixtures filled with N 220

Mixture number

Buna AP 452 100 ALIGN! 100 ALIGN! CORAX N 220 50 ' 50 ZnO RS 5 5 stearic acid 2 2 Ingraplast NS 10 10 Vulkacit Thiuram 1 - Vulkacit Mercapto 0.5 - M - 2 sulfur 1 1 Reverse: ^D max ' ^D (max + O ^/ ) ^ max “ ^D min 3.3 0

at a vulcanization temperature of 160 ° C.

EPDM mixtures, which are themselves reversible, show a further reduction of the reversion down to zero when the conventional accelerator mixtures (mixture 60) are replaced with N, N'-substituted bis- (2,4-diamino-s-triazine- 6-yl) oligosulfide (mixture 62).

Example 13

N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides in NBR mixtures filled with N 220 Mixture no. 63 65

Perbunan N 3307 NS CORAX N 220 ZnO RS stearic acid paraffin solid Mesamoll Vulcacit HS Vulcacit CZ M sulfur

Reverse:

^D max “ ^D (max + 60 ⁾ ) ^D max“ ^D min

100 ALIGN!

100 ALIGN!

1.5

1.5

1,2

1.5

1.5

1.5

1,2

8.0 5.6 at a vulcanization temperature of 170 ° C.

Properties of vulcanizate at 170 ° C, t 95% stress at 300% elongation 11.8 Shore hardness 68

14.6

At the same sulfur content, there is a strong increase in the voltage at the 300% elongation while reducing reverse. Example 14

Reverse stability for BR-mixtures filled with N 220 containing 220, N´-substituted bis- (2,4-diamino-s-triazin-6-yl) -ol gosulfides

Mixture number 66 67 Buna CB 100 ALIGN! 100 ALIGN! CORAX N 220 60 60 ZnO RS 3 3 stearic acid 2 2 Naftolen ZD 15 Dec 15 Dec Protector G 35 1 1 Vulkanox 4010 NA 1.5 1.5 Vulkacit NZ 1.5 - M - 1.5 Sulfur ’. · - '··' 1.5 · 1.5 Reverse: ^D max ' ^D (max + 60') ^D max ^_D min 30.3 20.8 at a vulcanization temperature of 170 Deň: 32 ° C. Properties of vulcanizate at 170 ´C stress at 300% elongation t 95% 8.6 8.9 t 95% + 75 ' 5.6 6.8

Due to the lower reverse of the BR mixtures, whose vulcanization is accelerated by substance M (mixture 67), the voltage drop at 300% elongation under severe overheating is significantly reduced compared to the reference mixture (mixture 66).

Example 15

Ν, N´-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides in NR / BR-based mixtures filled with N 220

Mixture number 69 72 RSS 1, ML (1 + 4) = 70-80 70 70 Buna CB 30 30 CORAX N 220 50 50 ZnO RS 5 5 stearic acid 2 2 Naftolen ZD 3 3

Vulkanox 4010 NA 2.5

Vulkanox HS 1.5

Protector G 35 1

Vulcacit MOZ 1.43

M sulfur 1.5

2.5

1.5 1

1.5

0.8

Reverse:

^D max ^D (max + 60 ^J ) ^D max ^_D min at vulcanization temperature 170

32.0 ° C.

23.8

The mixture based on NR and polybutadiene (mixture 72) shows using N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides compared to the mixture containing the semi-EV system (mixture 69). ) significantly reduce reverse.

Example 16

Crosslinking of natural rubber epoxidized to 50% (ENR 50) filled with N 220 by N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides

Mixture number 73 75 ENR SO 100 ALIGN! 100 ALIGN! CORAX N 220 50 50 ZnO RS 5 5 stearic acid 2 2 Vulkanox HS 2 2 Vulkacit MOZ 2.4 - Vulkacit thuran 1.6 M - 4,5 sulfur 0.3 0.3 Reverse: ^D max ^D (max + ^60;) ^ max “^ min 6.7 0.0 at a vulcanization temperature of 150 Deň: 32 ° C. Properties of vulcanizate at 150 ° C, t 95% tensile strength 18.7 24.6 voltage at 300% elongation 18.0 18.9 structural strength 12 12 Shore hardness 75 78

The use of Ν, Ν'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides (mixture 75) results in an improved reversal compared to conventional accelerators (mixture 73) while maintaining a voltage value of 300% elongation and greatly increase the structural strength.

Example 17

The retarding effect of Vulcalent E on the vulcanization of NR-mixtures vulcanized with N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides filled with N 220

Mixture number 82 85 86 RSS 1, ML4 = 70-80 100 ALIGN! 100 ALIGN! 100 ALIGN! CORAX N 220 50 50 50 ZnO RS 5 5 5 stearic acid 2 2 2 Naftolen ZD 3 3 3 Vulkanox 4010 NA 2.5 2.5 2.5 Vulkanox HS 1.5 1.5 1.5 Portector G 35 1 1 1 Vulkacit MOZ 1.43 - - M - 1.55 1.55 sulfur 1.5 0.8 0.8 Vulkalent E - - 1,2 t (min) at 170 ° C 3.8 2.9 4.1 Properties of vulcanizate at 170 ’C, t 95% voltage at 300% elongation 10.6 10.6 11.0 Addition of Vulkalent into mixtures accelerated Accelerator M

leads to an increase in the incubation time t1 above the level achievable with a conventional MOZ-accelerated mixture (mixture 82).

Example 18

Effect of Vulcalent E on NR-mixtures crosslinked with N, N'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfide and filled with N 220

Mixture number 90 93 94 RSS 1, ML (1 + 4) = 70-80 100 ALIGN! 100 ALIGN! 100 ALIGN! Ultrasil VP 3 gran. 25 25 25 CORAX N 220 25 25 25 ZnO RS 5 5 5 stearic acid 2 2 2 Naftolen ZD 3 3 3 Vulkanox 4010 NA 2.5 2.5 2.5 Vulkanox HS 1.5 1.5 1.5 Portector G 35 1 1 1 Vulkacit MOZ 1.43 - - M - 3.0 3.0 Vulkalent E - - 1,2 sulfur 1.5 0.8 · 0.8 Time to cure the mixture at 130 C (min) 29.5 16.5 29.0 170 ° C 4,5 3.7 4.8

With accelerant E, the acceleration of the Ν, Ν'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides (mixture 94) can be set to cure the mixture in a manner comparable to that of MOZ.

Claims (10)

1. Ν, Ν'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides of formula II wherein: R ¹ represents a hydrogen atom, R ² is hydrogen or benzyl, each of R ² , R ³ and R ⁴ being C 1 -C 8 alkyl, allyl, C 3 -C 8 cycloalkyl optionally substituted with 1 to 8 carbon atoms; 3 methyl, 2-hydroxyethylene, 3-hydroxypropyl, 2-hydroxypropyl or R ³ and R ⁴ together represent an alkylene group having 4 to 6 carbon atoms or a group of the formula - (ch ₂ -chx) ₂ y, where X is methyl or hydrogen; and Y represents oxygen or sulfur; and S _x represents a sulfur chain whose mean statistical length corresponds to the meaning of x = 4. Use of the compounds according to claim 1 as accelerators in vulcanizable mixtures based on one or more natural and / or synthetic rubbers, these mixtures containing fillers, sulfur and other conventional components and optionally containing further compounds according to claim 1 or conventional accelerators, in particular sulfenamides, dibensthiazolyldisulfide and / or thiuranes, sulfur donors and / or retardants and / or organosilanes. Use of the compounds according to claim 1 as crosslinkers in vulcanizable mixtures based on one or more natural and / or synthetic rubbers, said mixtures being free of sulfur, containing fillers and other conventional components and optionally containing further compounds according to claim 1 or conventional accelerators, in particular sulfonamides, dibenzthiazolyldisulfide and / or thiurams, sulfur donors and / or retardants and / or organosilanes. 4. Vulcanizable mixtures based on one or more natural and / or synthetic rubbers, containing fillers, sulfur and other conventional components, characterized in that they contain, per 100 parts by weight of rubber, 0.01 to 10, preferably 0.1 to 5 parts by weight of the compounds of claim 1 and their mutual. mixtures and / or mixtures thereof with conventional accelerators at a sulfur dosage of from 0.1 to 10 parts by weight per 100 parts by weight of rubber. 5. Vulcanizable mixtures based on one or more natural and / or synthetic rubbers, containing fillers and other conventional components but not containing sulfur, characterized in that they contain, per 100 parts by weight of rubber, 0.2 to 15 parts, preferably 0.3 to 15 parts. 8 parts of the compounds according to claim 1 or mixtures thereof or mixtures thereof with conventional accelerators. A process for the preparation of the Ν, Ν'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides of formula II according to claim 1, wherein: X is methyl or hydrogen; and Y represents oxygen or sulfur; and S _x length corresponds to the meaning of x = 4, characterized in that the corresponding tetrasulfides of the general formula I wherein R ¹ , R ² , R ³ and R ⁴ have the same meaning as in the general formula II, subject to disproportionation without the formation of free sulfur. 7. The process of claim 6 wherein the tetrasulfides of formula I are heated above their melting point. 8. A process according to claim 6, wherein the tetrasulfides of the formula I are dissolved in an inert organic solvent and the disproportionation reaction is allowed to proceed in the temperature range from 20 [deg.] C. to the boiling point of the solvent. A process for the preparation of the Ν, Ν'-substituted bis- (2,4-diamino-s-triazin-6-yl) oligosulfides of the general formula II according to claim 1, characterized in that an aqueous alkaline solution corresponding to The Ν, Ν'-substituted 2,4-diamino-6-mercaptotriazines are reacted in a two-phase system with a solution of sulfur trichloride S ₂ Cl ₂ in an inert solvent in which the tetrasulfides formed are soluble. Process according to claim 9, characterized in that chlorinated hydrocarbons, ethers or esters as well as aromatic hydrocarbons of ketones which are water-soluble are used as solvents.