CA1325805C - N,n'-substituted bis-(2,4-diamino-s-triazin-6-yl)- tetrasulfides and disproportionation products thereof, processes for their production and their use in vulcanizable rubber mixtures - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The invention relates to compounds corresponding to the following general formula in which R1, R2 are H; R2 is benzyl, R2, R3 and R4 are C1-C8 alkyl, allyl, C3-C8 cycloalkyl, unsubstituted or substituted by 1 to 3 methyl groups, 2-hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl or R3 and R4 (together) represents C4-C6 alkylene, -(CH2-CHX)2Y where X is H, CH3; Y is O, 5 and oligosulfidic disproportionation products thereof, of which the average statistical chain length corresponds to S4, and to a process for producing these compounds from the corresponding N,N'-substituted diaminomercaptotriazines.
The compounds according to the invention are used in vulcanizable rubber mixtures as crosslinking agents without sulfur or as vulcanization accelerators together with sulfur.

Description

:
132S80~

This invention relates to N,N~-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides, to a process for their production, to processes for the production of their dlsproportionation products, to the use of the tetrasulfides and s of the disproportionation products as cross-linking agents or vulcanization accelerators in rubber mixtures and to vulcanizable rubber mixtures containing them.
.
N,N'-substituted bis-(2~4-diamino-s-trlazln-6-yl)-disulfides are known and are described in DE-PS 1,669,954. They are prepared from the corresponding N,N'-substituted 2,4-diamino-6-mercaptotriazines by oxidation, for example with iodine, sodium ."3 hypochlorite or hydrogen peroxide. The most well known compound ` in this group is bis-(2-ethylamino-4-diethylaminotriazin-6-yl)- , 15 disulfide. Disulfides of this group may be used as accelerators in rubber mixtures.

The present invention provides compounds which improve the vulcanization behavior of rubber mixtures and which lmpart better properties to their vulcanizates and to provide processes , for the production of these compounds.
;' The present invention provides compounds corresponding to the following general formula:

.
'.'' .

, 30 :j .,, ~, ,,. ~k .`,' ~

'~
~, ~ - 1 -'~1 ,;~, .;~ .
. . .

,.~. . .

132~805 N~ N

S \ ~ N~L 54~

in which Rl and R2 are H; R2 is benzyl R2, R3 and R4 are Cl-C8 alkyl, preferably Cl-C4 alkyl, branched or unbranched, alkyl, C3-C8 cycloalkyl, unsubstituted or substituted by 1 to 3 methyl groups, 2-hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl or 15 R and R (together) represent C4-C6 alkylene, -(CH2-` CHX)2Y where H is CH3, H and Y is O, S.
The present invention also relates to a process forthe production of these compounds. The process for : producing the pure tetrasulfides with a linear S4-chain between the two substituted triazine rings is characterized in that an aqueous alkaline solution of the corresponding . N,N'-substituted 2,4-diamino-6-mercaptotriazines is ~ reacted in a two-phase system with'an S2C12 solution in `.~ an inert organic solvent, in which the reaction product is ` 25 insoluble or very sparingly soluble, at temperatures of from -5C to -<+20DC and preferably at a temperature of 0 DC. It is of advantage to prepare an alkaline aqueous solution of the mercaptotriazine which contains at least the stoichiometric quantity of alkali hydroxide required for the reaction and preferably an excess of from 1 to 20 mole ~D~ based on the mercaptotriazine used.
To this solution is added a solvent in which the end product of the reaction is insoluble or sparingly soluble, preferably a C5-C10 alkane or a C5-C8 cycloalkane, option-ally substituted by 1 to 3 methyl groups, and mixtures ;'' "

. ~ 2 ., .

. 132~8~5 1 thereof. This mixture is vigorously stirred and cooled,preferably to +10C. A solution of S2Ci2 in the solvent used is then added dropwise to this mixture with thorough cooling. S2C12 is used at least in a ratio of 2 moles mercaptotriazine to 1 mole S2C12, although this ratio may also be 2~ 1.2, depending on the excess of alkali.
Under these conditions, S2C12 has solely a condensing effect.
` The product formed is separated off by well known methods and is advantageously dried in vacuo ~10 Torr) at temperatures of up to +50C.
The present invention also relates to mixtures of compounds corresponding to the following general formula N N
N ~ N ~ N
~ N ~ N~ xN N (II) in which Rl, R2, R3 and R4 are as defined hereinbefore and Sx corresponds to an average statistical chain length with x = 4.
These mixtures, which are also referred to hereinafter as oligosulfides or disproportionates because they are formed by disproportionation of compounds corresponding to formula I, may be prepared by several methods.
The reaction conditions have to be controlled in such a way that no free sulfur is formed.
One process is characterized in that the isolated compound corresponding to formula I is heated beyond its Z melting point, preferably by 20 to 50C.
In another process, the compounds corresponding to ~ - 3 -,, .

13258~

formula I are dissolved in an inert organic solvent and the disproportionation reaction is carried out at temperatures between 20~C (standing at room temperature) and the boiling point of the solvent used.

One particularly elegant method comprises reacting an aqueous alkaline solution of the corresponding N,N'-substituted 2,4-diamino-6-mercaptotriazines in a two-phase system with a solution of S2C12 in an inert organic solvent which dissolves the tetrasulfide formed. The linear tetrasulfide formed is then immediately disproportionated to the mixture according to the invention which consists of oligosulfides.

Suitable solvents are, in particular, chlorinated ` hydrocarbons, for example CH2C12 and CHC13; ethers, esters, aromatic hydrocarbons and ketones are also suitable solvents for the disproportionation reaction, they may be used providing they form a two-phase mixture with water. The reaction conditions for the preparation of the disproportionates are otherwise identical with those under ;; which the compounds of formula I are produced.

~- 25 . ....................................................................... ~

' ~

132~8~5 The present invention also relates to the use of the compounds of formula I and II in vulcanizable rubber mixtures and to the rubber mixtures containing the compounds according to the invention.

When used as crosslinking agents or vulcanization accelerators, the tetrasulfides according to the invention or their disproportionates have been found to be distinctly superior to the standard compounds in use today.

A wide range of accelerators (J. van Alphen, Rubber Chemicals (1977, pages 1-46)) is available to the rubber-processing industry, preferably for sulfur vulcanization, including for example benzthiazolyl sulfenamides, ~5 benzthiazolyl disulfide and 2-mercaptobenzthiazole : or zinc salts thereof. In addition, there are a number .

- 4a -.
,. ~

~ ,; , 132580r) 1 of special compounds, such as thiuram disulfides and peroxides, which act as crosslinking agents even in the absence of other additives of sulfur, but which are often used in combination with sulfur as accelerators. The particular application is determined by the particular effect to be obtained.
Today, the most widely used accelerators in practice, particularly among the elastomers accessible to accelerated sulfur vulcanization, are the benzthiazolyl sulfenamides.
However, new production processes and new products and also the ever-present need for rationalization have in recent years brought about changes in the requirements which accelerators have to satisfy compared with the past to such an extent that, today, it can be difficult to satisfy the quality demands imposed on the vulcanization process and on the properties of the vulcanizates with the accelerators or crosslinking agents currently available for accelerated sulfur vulcanization.
Another disadvantage of certain conventional acceler-ators (for example certain sulfenamides, thiurams), which ` can now no longer be ignored, is that amines can be released during the vulcanization process and, where they are nitrosatable, lead to the for~ation of nitrosamines in the vulcanizate which, if they are toxic, can be expected permanently to restrict the potentional applications ofthese accelerators.
Another crucial disadvantage of the benzthiazolyl accelerators, particularly benzthiazolyl sulfenamides, is their increasingly pronounced tendency towards reversion with increasing vulcanization temperature during the often necessary overheating of the vulcanizates, particularly wherc rubbers susceptible to reversion, such as natural ruhber and polyisoprene and blends thereof with synthetic rubbers, are used. ~lowever, the same also applies to synthetic rubbers of all kinds if the reversion process is 132~0~

1 not masked by thermal crosslinking. The reversion rate `~ increases so drastically, particularly with increasing vulcanization temperature, that, firstly, there is a significant reduction in the crosslinking density, even with optimal vulcanization per se, secondly the vulcaniz-ation optimum assumes the form of a peak rather than a plateau, which makes it extremely difficult to reproduce optimal vulcanization properties, and thirdly there is an unavoidable reduction in the crosslinking density during the often necessary overvulcanization, which leads to a loss of uniformity of crosslinking in the vulcanizate, particularly in the case of thick-walled rubber articles.
Commensurate with the increase in reversion, there is a reduction in the performance of the vulcanizates which is reflected, for example, in reduced 300% modulus and abrasion resistance, etc.
The reversion effects mentioned can be remedied to a certain extent by reducing the sulfur content and increasing the accelerator content, i.e. by using so-called semi-EV-systems (L. Bateman, 1963 "The Chemistry and Physics of Rubber-like Substances", pages 522 et seq.). However, ; this reduction in reversion is achieved through a change in the crosslinked structure (rati,o of -Sx-, -S-S-, -S- bonds) in favor of monosulfidic crosslinking sites 1 25 which can adversely affect the vulcanizate properties.
However, this measure becomes more ineffective, the higher the vulcanization temperature.
The disadvantages of the benzthiazole accelerators limit their usefulness with increasing vulcanization temperature and impose certain limits on the efforts of the rubber industry to increase productivity by using ' higher vulcanization temperatures.
Surprisingly, the N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides and their disproportionation products, both in their use as accelerators in sulfur 132~8~5 1 vulcanization and in their use as crosslinkers, i.e.
without the additional use of sulfur, have proved to be compounds which impart extremely high reversion stability - even in the event of severe overheating - to the rubber mixtures prepared with them, even at high vulcanization temperatures, as reflected in the fact that, where they are used, the otherwise usual reversion process occurs to only a minor extent, if at all. The surprising fact that the crosslinking sites formed by the N,N'-substituted bis-~2,4-diamino-s-triazin-6-yl)-tetrasulfides according to the invention and their disproportionates are extremely reversion-stable and thermostable means that, where they are used in rubber mixtures, even at high vulcanization temperatures, the vulcanizates obtained on completion of the crosslinking reaction show a high performance level which they maintain even in the event of strong overheating.
These two effects taken together enable increases in productivity to be achieved in the rubber-processing industry without any loss of vulcanizate performance by increasing the vulcanization temperature.
Commercial polysulfides,-such as Robac(R)P 25 (Robinson, dipentamethylene thiuram tetrasulfide) and Tetron(R)A (Du Pont, dipentamethylene thiuram hexasulfide) or dibenzthiazolyl tetrasulfide do not achieve even remotely comparable reversion stability.
The use of the N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides according to the invention and their disproportionation products encompasses the rubber mixtures known from the prior art based on natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), isobutylene-isoprene rubber (IIR), ethylene-propylene terpolymer (EPDM), nitrile rubber (MBR), halogen-containing rubbers and also epoxidized natural rubbers (ENR) and blends thereof. The use of the N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides 132~8V5 1 according to the invention and their disproportionation products is of particular significance in the case of reversion-sensitive rubbers, such as for example natural rubber, isoprene and butadiene rubbers and blends thereof S with one another or with other r~bbers.
The N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides according to the invention and their disproportionation products are used as crosslinking agents in rubber mixtures in a quantity of from 0.2 to 15 parts by weight and preferably in a quantity of from 0.3 to 8 parts by weight, based on 100 parts of rubber.
In accelerated sulfur vulcanization, the N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides according to the invention or their disproportionation ! 15 products are used as accelerators in quantities of from 0.01 to 10 parts and preferably in quantities of from 0.1 to 5 parts, based on 100 parts of rubber, for sulfur dosages of from 1 to 10 parts. A molar ratio of the accelerators according to the invention to sulfur (S8) of 1:0.5-1.5 is preferred. In order to obtain a certain range of variation of the vulcanization kinetics, it can be useful to use two or more N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfildes or their dispro-portionates in admixture with one another, the substitution being made on a molar basis in order to keep to the quantities and particularly to the preferred accelerator-to-sulfur ratio mentioned above. The same also applies where N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides or their disproportionates are used as crosslinking agents without sulfur.
~ gain for kinetic reasons, it can be useful to use the N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides or their disproportionation products in admixture with conventional accelerators, such as for example sulfenamides and thiurams. These measures are 132~8~

1 occasionally to the detriment of reversion stability by comparison with the N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide vulcanizates. However, they do have a positive effect on reversion behavior where conventional accelerators are partly replaced by N,N'-substituted bis-t2,4-diamino-s-triazin-6-yl)-tetrasulfides or their disproportionates.
A further significant effect on incubation time where the compounds according to the invention are used in rubber mixtures can be obtained by combination with commercial vulcanization retarders, such as Santoguard(R) PVI (N-~cyclohexylthio)-phthalimide) and Vulkalent(R)E (N-phenyl-N-(trichloromethylsulfenyl)-benzenesulfonamide).
Vulkalent( )E~a product of Bayer AG, has proved to be the most effective retarder. With increasing addition of Vulkalent( )E, there is a linear increase in the incubation time of mixtures containing N,N'-sustituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides or their dispro-portionates.
Where N,N'-substituted bis-(2,4-diamino-s-triazin-6-' yl)-tetrasulfides or their disproportionates are used as crosslinking agents, it has proved to be best to keep the molar ratio of N,N'-substituted bis-(2,4-diamino-s-triazin-6~yl)-tetrasulfides or their disproportionates to Vulkalent 25 E at 1:0.5-1.5 and preferably at 1:0.8-1.2 parts to 100 parts of rubber.
Of greater importance is the use of retarders, particularly Vulkalent E, in accelerated sulfur vulcaniz-ation using N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides and their dispr~portionates and also mixtures thereof. The intended increase in the incub-ation time of the crosslinking reaction is occasionally accompanied by a slight reduction in the crosslinking velocity, which can be arrested by increasing the temper-ature, and by a slight reduction in reversion stability.

-~32~8~

1 In this case, it has also been found to be advisable to adjust the molar ratio of N,N'-substituted bis-~2,4-diamino-s-triazin-6-yl)-tetrasulfides or their disproportionates to Vulkalent E to 1:0.5-1.5 and preferably to 1:0.8-1.2, 5 the sulfur content being kept between 0.1 and 10 parts and preferably between 0.5 and 8 parts, based on 100 parts of rubber, depending on the type of mixture.
On the basis of these dosage guidelines, it is possible to solve many of the vulcanization problems in 10 question without any significant deterioration in the . properties of the vulcanizates which would go against the essence of the invention.
Mixtures which contain only silica or carbon black/
silica blends with silica contents of more than 15 parts :
~ 15 to 100 parts of rubber are very difficult or even impossible i.; .
to crosslink with conventional sulfur vulcanization systems.
On the one hand, they particularly undergo reversion, on the other hand they prevent adjustment of the crosslinking density dictated by the requirements which the end products 3 20 have to satisfy. This is one of the reasons why silicas are preferably used in soling material and, hitherto, relatively infrequently in dynamically stressed products.
Surprisingly, it is possible with bis-(2,4-diamino-s-~, triazin-6-yl)-tetrasulfides and their disproportionates, 25 both as accelerators and as crosslinking agents (without sulfur), substantially to eliminate reversion in mixtures containing black/white blends with silica contents of more than 15 parts to 100 parts of rubber and also in silica-filled mixtures and, at the same timé, to increase the 30 crosslinking density, which is reflected in a high modulus level for silica mixtures.
The N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides according to the invention and their disproportionation products may also be used in combination 35 with oligosulfidic organosilanes, for example -- 132~80~

1 [(RO)3 - Si - (CH2)n ]2 Sx (RO)3-Si-(CH2)n-SH

with x = 2 - 6, R = Cl-C6 alkyl, cyclohexyl, n = 2 or 3 or ~ CH3 ~
(RO)3 Si ~ (CH2)n ~ 2Sx with x = 2 - 6, preferably 3, preferably bis-(3-triethoxysilylpropyl)-tetrasulfide (Si 69, Degussa AG). N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides and their disproportionates may be used with advantage in sulfur-free organosilane crosslinking instead of the accelerators described in 15 DE-PS 25 36 674 and in the sulfur vulcanization with organosilanes described in DE-PS 22 55 577 and also in the production of reversion-stable organosilane-con-taining rubber mixtures by synthesis of equilibrium cure j systems (DE-PS 28 48 559J.
' 20 This applies both to carbon-black-filled mixtures and to mixtures containing carbon black/silica blends and also to mixtures filled only with silicas. Mineral fillers may also be added to the m~xtures mentioned with-out any adverse effects. In this case, rubber/filler bonds are formed in the presence of silica fillers or carbon black/silica blends (Kautschuk & Gummi, Kunststoffe, number 8, 1977, pages 516-523, number 10, 1979, pages 760-765 and number 4, 1981, pages 280-284) while rubber/
rubber bonds are formed in the presence of carbon blacks.
~he formation of rubber/rubber crosslinking sites in the presence of carbon black or the formation of rubber/
filler crosslinking sites in the presence of silica or the formation of both types of crosslinking sites in the presence o~ carbon black/silica blends in any ratios is also possible where N,N'-substituted bis-(2,4-diamino-s-1325~

1 triazin-6-yl)-tetrasulfides or their disproportionates are used individually or in admixture with one another or in admixture with conventional accelerators together with conventional sulfur donors, such as for example Sulfasan(R) R (morpholine disulfide).
The compounds according to the invention are used in rubber mixtures which may contain other typical components, such as for example:
- standard reinforcing systems, i.e. furnace blacks, channel blacks, flame blacks, thermal blacks, acetylene blacks, arc blacks, CC-blacks, etc.; synthetic fillers, such as silicas, silicates, aluminium oxide hydrates, calcium carbonates; natural fillers, such as clays, siliceous chalks, chalks, talcums, etc. and silane-modified fillers and blends thereof in quantities offrom 5 to 300 parts to 100 parts of rubber, silicas and silicates being particularly preferred, - zinc oxide and stearic acid as vuicanization promoters in quantities of from 0.5 to 10 parts of rubber, - typical antiagers, antiozonants, anti-fatigue agents, such as for example IPPD, TMQ, etc. and also waxes as ; light stabilizers and blends thereof, - plasticizers such as, for example, aromatic, naphthenic, paraffinic, synthetic plasticizers and blends thereof, - optionally, other silanes, such as y-chloropropyl tri-alkoxysilanes, vinyl trialkoxy silanes and aminoalkyl trialkoxysilanes and also blends thereof in a quantity of from 0.1 to 15 parts and preferably in a quantity of from 1 to 10 parts to 100 parts of fillers containing silanol groups, such as silicas, silicates, clays etc., - optionally, dyes and processing aids in the usual quantities.
The range of application of the N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides extends to rubber mixtures of the ~ - 12 -132~

1 type normally used in tire production and to technical articles, such as for example mixtures for conveyor belts, V-belts, molded articles, hoses with and without reinforae-ment, rubber covers for rollers, linings, molded profiles, : 5 freehand articles, films, shoe soles and uppers, cables, solid rubber tires and vulcanizates thereof.The following products are mentioned as examples of the compounds according to the invention:
A bis-(2-ethylamino-4-di-isopropylamino-s-triazin-6-yl)-tetrasulfide B bis-(2-n-butylamino-4-diethylamino-s-triazin-6-yl)-tetrasulfide C Bis-(2-isopropylamino-4-di-isopropylamino-s-triazin-6-yl)-tetrasulfide D bis-(2-ethylamino-4-di-isobutylamino-s-triazin-6-yl)-. tetrasulfide E bis-(2-ethylamino-4-di-n-propylamino-s-triazin-6-yl)-tetrasulfide F bis-(2-n-propylamino-4-diethylamino-s-triazin-6-yl)-; 20 tetrasulfide G bis-(2-n-propylamino-4-di-n-propylamino-s-triazin-6-yl)-tetrasulfide H bis-(2-n-butylamino-4-di-n-propylamino-s-triazin-6-yl)-tetrasulfide 25 I bis-(2-ethylamino-4-di-n-butylamino-s-triazin-6-yl)-tetrasulfide K bis-~-isopropylamino-4-di-isopropylamino-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 O bis-(2-amino-4-diethylamino-s-triazin-6-yl)-oligo-sulfide mixture 132~8~

454 g of 2-ethylamino-4-diethylamino-6-mercapto-triazine are dissolved in soda lye prepared from 84 g NaOH ~ 1.5 liters H2O.
The solution is poured into a 4-liter three-necked flask. After the addition of 1.5 liters light petrol (Bp. 80 - 110C). the mixture is cooled with vigorous stirring to 0C.
A solution of 137 g of S2C12 in 100 ml petrol is then run in over a period of 20 minutes during which the temperature must not exceed +5C.
The tetrasulfide precipitates immediately. On completion of the reaction, the reaction mixture is stirred for 5 minutes, filtered under suction and washed.
` 15 The snow-white fine powder is dried in vacuo (12 Torr) at 40 - 45C.
; Yield: 499.5 g, corresponding to 97.1% of the theoretical.
Mp.: 149 - 150C.
~ Analysis:
; 20 Bis-(2-ethylamino-4-diethylamino-s-triazin-6-yl)-tetrasulfide Molecular weight 516, C18H32NloS4 Calculated: C 41.9 H 6.2 N 27.1 S 24.8 Found: 41.8 6.5 26.8' 24.8 Analysis by TLC and HPLC shows that the product contains 97.1% linear tetrasulfide.

56.6 g of 2-ethylamino-4-di-n-butylamino-6-mercapto-triazine are dissolved in a solution of 8.8 g of NaOH in 250 ml water. 250 ml petrol are then added, after which the mixture is cooled with thorough stirring to +5~C. A solution of 13.5 g S2C12 in 30 ml petrol is then run in. A white precipitate is immediately formed.
On completion of the reaction, the reaction mixture is worked up in the same way as in Example 1. Yield: 56.g, 13258~5 1 corresponding to 89.2% of the theoretical.
26 48NloS4 (molecular weight 628) Calculated: C 49.68 H 7.64 N 22.29 S 20.38 Found: C 49.59 7.59 22.18 20.40 HPLC analysis: purity >96~.

107.6 g of 2-i-propylamino-4-diisopropylamino-6-mercaptotriazine are dissolved in soda lye prepared from 10 17.6 g NaOH in 600 ml H2O. 600 ml methylene chloride are then added.
A solution of 27 g S2C12 in 50 ml CH2C12 is then run in at 0 to 5C. On completion of the reaction, the organic phase is separated off in a separation funnel, dried and concentrated in vacuo. An amorphous powder is obtained; softening point 90C. Yield: 112.5 g, corresponding to 94~ of the theoretical.
y C24H44NloS4 (molecular weight 600) Calculated: C 48 H 7.33 N 23.3 S 21.3 20 Found: 48.2 7.36 23.01 20.95 45.4 g of 2-ethylamino-4-diethylamino-6-mercapto-triazine are dissolved in soda lye prepared from 8.8 g NaOH and 200 ml water. 200 ml methylene chloride are then added. The mixture is thoroughly stirred and cooled to 0C. ]4 g S2C12 are then dissolved in 50 ml CH2C12 and the resulting solution run into the mercaptide solution.
The reaction product dissolves in CH2C12. On com-pletion of the reaction, the phases are separated and the CH2C12 solution is worked up, giving an amorphous powder having a softening point of approx. 110C. Yield: 46.7 g, corresponding to 90.5~ of the theoretical.
y 18H32NloS4 tmolecular weight 516) Calculated: N 27.1 S 24.8 Found: 26.8 24.4 , 132~8~

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

50 g of bis-~2-ethylamino-4-diethylamino-s-triazin-6-yl)-tetrasulfide having a purity of 97.1% are placed in a spherical flask and heated for 1 hour to 160C on an oil bath. On cooling, the melt solidifies in amorphous form.
According to analysis by T~C, the product contains another 3 oligosulfides in addition approx. 50% of starting product.

, 70.25 g of 2-cyclohexylamino-4-diethylamino-6-mercapto-triazine are dissolved in 11 g of NaOH and 250 ml of water.
15 250 ml of chloroform are then added, after which a solution of 16.8 g of S2C12 in 30 ml of CHC13 is run in with vigorous stirring. On completion of the reaction, the phases are separated and the chloroform phase is worked up, giving 71.9 g of a white amorphous powder, corresponding to a yield of 92% of the theoretical.
y 26H44NloS4 (molecular weight 624) Calculated: C 50 H 7.05 N 22.4 S 20.51 Found: 49.1 6.90 21.8 20 According to analysis by TLC, the product consists of approx. 30% linear S4-product and 70% oligosulfides, but contains no free sulfur.

\ - 16 -132~83~

Test Standards:
The physical tests were carried out at room temperature in accordance with the following standards:
Measured in Tensile strength, DIN 53 504 Mpa elongation at break and modulus value on 6 mm thick rings Shore-A-hardness DIN 53 505 Firestone ball rebound AD 20 245 Reversion~ DE-PS 2 848 559 Incubation time t DIN 53 529 (mins.) Scorch time ASTM D 2084 (mins.) . .
The names and abbreviations used in the Application Examples have the following meanings:

: RSS: Ribbed Smoked Sheet (natural rubber) CORAX(R) N220 Carbon black, BET surfa~e i2u m2jg (Degussa) Naftolen( ) ZD: Plasticizer of hydrcarbons Ingraplast( )NS: Plasticizer of naphthenic hydrocarbons Vulkanox(R) 301û NA: N-isopropyl-N'-phenyl-p-phenylenediamine Vulkanox(R)HS: Poly-2,2,4-trimethyl-1,2-dihydroquinoline Mesamoll(R): Alkylsulfonic acid ester of phenol and cresol Robac P 25: Dipentamethylene thiuram tetrasulfide Tetrone A: Dipentamethylene thiuram hexasulfide Protektor( )G35: Anti-ozonant wax Vulkacit(R)MOZ: Benzthiazolyl-2-morpholinosulfenamide Vulkacit(R)Mercapto: 2-mercaptobenzthiazole Vulkacit(R) Thiuram: Tetramethyl thiuram monosulfide Vulkacit(R) CZ: N-cyclohexyl-2-benzthiazole sulfenamide Vulkalent(R)E: N-phenyl-N-(trichloromethylsulfenyl)-- benzene sulfonamide PVI: N-cyclohexylphthalimide Ultrasil(R)VN3: Precipitated silica (Degussa) Gran. Granulate \ - 17 ~

132~8~

V143: Bis-(2-ethylamino-4-diethylamino-s-triazin-6-yl)-disulfide Vulcacit(R)NZ: Benzothiazyl-2-tert.-butyl sulfenamide 132~80~

EX~MPLE 7 Reversion stability of N220-filled NR (without sulfur) crosslinked with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides 1 2 3 4 ' RSS 1, ML4 = 70-80 100 100 100 100 ZnO RS 5 5 5 5 Stearic acid 2 2 2 2 Naftolen ZD 3 3 3 3 Vulkanox 4010NA 2.5 2.5 2.5 2.5 Vulkanox HS 1.5 1.5 1.5 1.5 Protector G35 Vulkacit MOZ 1.43 - - -V143 - 1.29 Santoguard PVI - 0.4 - -_ - 3.34 D - - - 4.10 Sulfur 1.5 1.5 Reversion:
max ~ D(max+60') 30.1 8.6 2.3 2.1 D - D
at 170C vulcanization temperature 132~80~

Example 7 continued:
Reversion stability of N220-filled NR (without sulfur) crosslinked with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-oligosulfides RSS 1, ML4 = 70-80 100 100 100 ZnO RS 5 5 5 Stearic acid 2 2 2 Naftolen ~D 3 3 3 Vulkanox 4010NA 2.5 2.5 2.5 Vulkanox HS 1.5 1.5 1.5 Protector G35 K 3.84 L - 3.62 M - - 4.0 Reversion:
Dmax D(max+60~ ) 2.5 3.1 2.3 Dmax min at 170C vulcanization temperature When used as crosslinking agents (without sulfur), the N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-oligo-sulfides according to the invention prove to be extremely reversion-stable in carbon-black-filled NR mixtures (mixtures 3-7) by comparison with a mixture containing a semi-EV-system (mixture 1) or a bis-(2-ethylamino-4-diethylamino-s-triazin-6-yl)-disulfide (V143) (mixture 2).

132~80~

Reversion stability of N220/silica-filled NR (without sulfur) crosslinked with N,N'-substiteuted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides RSS 1, ML 1~4 = 70-80 100 100 100 100 100 100 100 100 Ultrasil VN3 Gran. 25 25 25 25 25 25 25 25 ZnO RS 5 5 5 5 5 5 5 5 Stearic acid, 2 2 2 2 2 2 2 2 Naftolen ZD 3 3 3 3 3 3 3 3 Vulkanox 4010NA2.5 2.5 2.52.5 2.5 2.5 2.5 2.5 Vulkanox HS 1.5 1.5 1.51.5 1.5 1.5 1.5 1.5 Protector G35 Vulkacit MOZ 1.43 C - 3.48 - - - - - -E - - 3.46 G - - - 3.62 I - - - - 3.78 K - - - - - 3.48 - -L - - - - - - 3.62 M - - - - - - - 3.0 Sulfur 1.5 Reversion:
Dmax (max~60') (%) 47.1 1.8 2.4 3.3 6.2 2.5 3.1 4.7 max min at 170C vulcanization temperature Silica-containing NR mixtures show particularly pronounced reversion phenomena, even where semi-EV-systems are used (mixture 8). With the N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra- or -oligosulfides used as crosslinking agents in accordance with the invention (mixtures 9-15), an a~most reversionless state is achieved for otherwise the same mixture composition.

~ - 21 -132~8~

Reversion stability of N220-filled NR accelerated with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra-sulfides RSS 1, MLl+4 = 70-80 100 100 lq0 100 100 100 100100 100 COI?AX N220 50 50 50 50 50 50 50 50 50 ZnO RS 5 5 5 5 5 5 5 5 5 Stearic acid 2 2 2 2 2 2 2 2 2 Naftolen ZD 3 3 3 3 3 3 3 3 3 Vulkanox 4010NA 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.52.5 Vulkanox HS ' 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.51.5 Protector G 35 Vulkacit MOZ 1.43 - - - - - - - -B - 1.66 C -- -- 1.74 D - - - 1.76 E - - - - 1.73 F - - - - - 1.65 G - - - - - - 1.81 H - - - - - - - 1.82 -- - - - - - - - 1.82 Sulfur 1.5 0.8 0.8 0.8 0.8 0.8 0.8 0.80.8 Reversion:
max (max+60')(%)31.9 0.4 0.0 0.0 1.3 1.3 2.0 1.22.1 max min at 170C vulcanization temperature Vulcanizate data at 170C, t 95%
Tensile strength23.0 22.624.1 21.320.8 19.922.1 22.023.2 Modulus 300~6 9.6 10.910.9 10.5 9.1 10.410.8 11.910.5 With equimolar accelerator dosage, the sulfur dosage can be reduced in the case of the N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra- or -oligosulfides. Inspite of this, higher modulus-300% values are obtained. The mixtures pre-132~80~

EXAMPLE 9 continued:
Reversion stability of N220-filled NR accelerated with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra-sulfides RSS 1, MLl+4 = 70-80 100 100 100 ZnO RS 5 5 5 Stearic acid 2 2 2 Naftolen ZD, 3 3 3 Vulkanox 4010NA 2.5 2.5 2.5 Vulkanox HS 1.5 1.5 1.5 Protector G35 K 1.74 L - 1.81 M - - 1.5 Sulfur 0. 8 0 . 8 0 . 8 Reversion:
D -D
max (maX+60 )(96) 0.4 1.5 5.2 max min at 170C vulcanization temperature Vulcanizate data at 170 C, t9596 Tensile strength22.9 24.2 22 . 2 Mbdulus 300~ 10.3 10.0 10.6 pared with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra- or -oligosulfides (mixtures 17-27) prove to be extremely reversion-stable against a semi-EV-system (mixture 16).

1325~5 Effectiveness comparison between sulfenamide and N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide acceleration in N220-filled NR for the same S8 dosage RSS 1 ML(1+4) = 70-80 100 100 ZnO RS 5 5 Stearic acid 2 2 Naftolen Zp 3 3 Protector G35 Vulkanox 4010NA 2.5 2.5 Vulkanox HS 1.5 1.5 Vulkacit MOZ 1.43 D - 1.76 Sulfur 1.5 1.5 Reversion:
max (max+60')(%) 31.9 5.1 max min at 170 DC vulcanization temperature Vulcanizate data at 160C, t 95~
Modulus 300~, MPa 10.6 12.8 Shore-A-hardness 63 64 Example 9 compares MOZ with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides or their disproportion-ation products at different sulfur concentrations. If, by contrast, the sulfur concentration is kept constant for an equimolar accelerator dosage, the difference in reversion stays, whereas the modulus 300% value increases considerably.

` 1325gO~

Comparison of the reversion behavior of commercial oligo-sulfides and dibenzthiazolyl tetrasulfides against N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-oligosulfide in N220-filled NR

RSS 1, ML(1~4) = 70-80100100 100 100 ZnO RS 5 5 5 5 Stearic acid 2 2 2 2 Naftolen ZD 3 3 3 3 Vulkanox 4010NA 2.52.5 2.5 2.5 Vulkanox HS 1.51.5 1.5 1.5 Protector ~35 Robac P25 1.12 Tetrone A - 1.3 Dibenzthiazolyl tetrasulfide - - 1.15 M - - - 1.5 Sulfur 0.80.8 0.8 0.8 Scorch time 170C 1.41.9 2.7 3.1 (t 10~), mins.
Reversion:
max (max+60') (~) 18.5 21.3 35.7 3.2 max min at 170C vulcanization temperature Vulcanizate data at 170C, t 95%
Tensile strength 23.1 21.2 18.9 23.6 Modulus 300% 9.4 9.5 7.3 10.4 Commercial oligosulfides (mixtures 30 and 31) and dibenzthiazolyl tetrasulfide (mixture 32) show several times higher reversion in NR than an N,N'-subtituted bis-(2,4-diamino-s-triazin-6-y')-oligosulfide (mixture 33).

~ - 25 -1325~

Blend of N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide with sulfur donor in N220-filled NR

RSS 1, ML(1+4) = 70-80 100 100 ZnO RS 5 5 Stearic acid 2 2 Naftolen ZD 3 3 ProtectorlG 35 Vulkanox 401ONA 2.5 2.5 Vulkanox HS 1.5 1.5 Vulkacit MOZ 1.43 Sulfasan R - 0.7 D - 1.76 Sulfur 1.5 Reversion:
max (max+60 )(~) 30.6 2.1 max min at 170C vulcanization temperature Where N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide is used with Sulfasan R as sulfur donor (mixture 35), there is a distinct improvement in reversion over conventional sulfenamide acceleration (mixture 34).

132~8~

Blend of commercial accelerators with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide in N220-filled NR

RSS 1, ML(1+4)=70-80 100 100 100 100 100 100 100 100 100 ZnO RS 5 5 5 5 5 5 5 5 5 Stearic acid 2 2 2 2 2 2 2 2 2 Naftolen ZD 3 3 3 3 3 3 3 3 3 Vulkanox 4010NA 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Vulkanox HSI 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Protector G35 Vulkacit MOZ 1.43 0.71 1.5 - - - - - -Vulkacit DM - - - 1.56 0.78 1.56 - - -Vulkacit Merkapto - - - - - - 1.2 0.6 1.2 B - 0.8 1.58 - 0.8 1.58 - 0.8 1.58 Sulfur 1.5 1.5 - 1.5 1.5 - 1.5 1.5 Reversion:
Dmax (max+60 )(%) 28.7 16.8 5.7 31.2 16.1 4.1 28.7 14.9 4.5 Dmax Dmin at 170C vulcanization temperature Vulcanizate data at 170C
Mbdulus at 300%, t95% 11.3 11.9 6.8 9.0 11.4 7.0 7.8 11.3 5.9 t95%+80' 8.9 10.7 6.7 7.5 10.5 6.9 6.5 10.8 5.9 ::~
The joint use of commercial accelerators with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides (mixtures 37, 40,41) produces a clear improvement in reversion behavior over the sole use of the commercial accelerators (mixtures 36,39,42).
A furLher increase in reversion stability may be obtained by elimination of the sulfur (mixtures 38,41,44).

; - 27 -- 132580~

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

RSS 1, ML(1+4)=70-80100 100 100 100 ZnO RS 5 5 5 5 Stearic acid 2 2 2 2 Naftolen ZD 3 3 3 3 Vulkanox 4010NA 2.5 2.5 2.5 2.5 Vulkanox HS 1.5 1.5 1.5 1.5 Protector G35 Vulkacit MOZ 1.43 M 1.5 -0.75 B - - 1.660.83 Sulfur 1.5 0.8 0.8 0.8 Reversion:
max (max+60')(%) 30.1 2.3 0.4 1.2 max min at 170C vulcanization temperature The use of N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides differing in their reversion stability in combination with one another produces a set of values which lies between the pure substances (mixture 48).

13278~

Reversion in B-accelerated rubber filled with carbon black/silica blend RSS 1, ML(1+4)=70-80100 100 Ultrasil VN3 Gran. 25 25 ZnO RS 5 5 Stearic acid 2 2 Naftolen b 3 3 Protector G35 Vulkanox 4010NA 2.5 2.5 Vulkanox HS 1.5 1.5 Vulkacit MOZ 1.43 B - 1.67 Sulfur 1.5 0.8 Reversion:
max (max+60')(~) 46.7 10.8 max min at 170C vulcanization temperature When the sulfenamide accelerator (mixture 49) is replaced by N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide (mixture 50), there is a drastic reduction in reversion.

132~80~

N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra-and-oligosulfides in N220-filled SBR

ZnO RS 5 5 5 5 5 Stearic acid 2 2 2 2 2 Naftolen ZD 3 3 3 3 3 Protector G35 Vulkanox 4010NA 2.5 2.5 2.52.5 2.5 Vulkanox HS 1.5 1.5 1.51.5 1.5 Protector G35 Vulkacit MOZ 1.43 B - 1.66 F - - 1.58 K - - - 1.5 M - - - - 1.5 Sulfur 1.51.5 1.51.5 1.5 Reversion:
max (max+60')(~) 12.9 11.3 11.5 9.2 12.5 max min at 170C vulcanization temperature Vulcanizate data at 170C, t 95%
Tensile strength 20.6 21.3 20.8 20.5 lS.9 Modulus 300~ 10.0 11. 6 12.2 12.1 12.3 Elongation at break 460 44,0 420 420 390 Shore hardness 61 63 63 63 64 For the same sulfur concentration, N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra and -oligosulfides (mixtures 52-55) show a distinctly higher modulus value and slightly improved reversion properties in SBR 1500 compared with conventional acceleration (mixture 51).
,.

132~

N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra-and -oligosulfides in N220-filled isoprene rubber Polyisoprene 3,4 100 100 100 100 ZnO RS 5 5 5 5 Stearic acid 2 2 2 2 Naftolen ZD 3 3 3 3 Vulkanox 4010NA 2.5 2.5 2.5 2.5 . Vulkanox HS 1.5 1.5 1.5 1.5 Protector G35 Vulkacit MOZ 1.43 B - 1.76 L - - 1.6 i M - - - 1.5 ` Sulfur 1.5 0.8 0.8 0.8 Reversion:
max (max+60')(%)21.0 2.1 0.0 0.0 max min at 170C vulcanization temperature Vulcanizate data at 170C
Modulus 300% t95% 7.9 6.6 6.3 6.4 t95~+80'6.2 6.8 6.3 7.1 In polyisoprene rubber, the use of N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra- and oligosulfides (mixtures 57-59) again produces a distinct improvement in reversion over conventional accelerators (mixture 56).
This improvement is also reflected in the stability of the vulcanizate data in the event of distinct overheating.

132~8~5 N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra-and oligosulfides in N220-filled EPDM

Buna AP 451 100 100 100 ZnO RS 5 5 5 Stearic acid 2 2 2 Ingraplast NS 10 10 10 Vulkacit Thiuram Vulkacit Mercapto 0.5 B - 2.93 M - - 2.5 Sulfur Reversion:
max (max+60') (~) 3 3 0 0 0 0 max min at 160C vulcanization temperature ;

EPDM mixtures which are already hi~hly reversion-stable show a further reduction in reversion to zero if conventional accelerator mixtures (mixture 60) are replaced by N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra- and oligosulfides (mixtures 61 and 62).

132~

N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra-and oligosulfides in N220-filled NBR

Perbunan N3307NS 100100 100 ZnO RS 5 5 5 Stearic acid Paraffin solid Mesamoll ' 10 10 10 Vulkanox HS 1.5 1.5 1.5 Vulkacit CZ 1.5 1.5 1.5 : D - 1.76 M - - 1.5 Sulfur 1.2 1.2 1.2 Reversion:
Dmax D(max+60') D -D (%) 8.0 5.4 5.6 ` max min at 170C vulcanization temperature Vulcanizate data at 170C, t95%
Modulus 300% 11.8 14.0 14.6 Shore hardness 6'8 69 69 For the same sulfur content, replacement by N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra- and oligosulfides (mixtures 64 and 65) in NBR produces a distinct increase in the modulus value at 300% elongation and a reduction in reversion compared with the reference mixture (mixture 63).

132~80~

Reversion stability of N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-oligosulfides in N220-filled BR

Buna CB 10 .100 100 100 ZnO RS 3 3 3 Stearic acid 2 2 2 Naftolen ZD 15 15 15 Protector~G35 Vulkanox 4010NA 1.5 1.5 1.5 Vulkacit NZ 1.5 M - 1.5 D - - 1.76 Sulfur 1.5 1.5 1.5 Reversion:
max (max+60')(%) 30.3 20.8 19.1 max min at 170~C vulcanization temperature Vulcanizate data at 170C
Modulus 300% t 95% 8.6 8.9 8.2 t 95%+75' 5J6 6.8 6.6 By virtue of the lower reversion of the M- and D-accelerated BR mixtures (mixtures 67 and 68), the reduction in the modulus 300~ value in the event of strong overheating is far smaller than in the reference mixture (mixture 66).

13258~

N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra-and oligosulfides in N220-filled NR/BR blend RSS 1, ML(1+4)=70-80 70 70 70 70 Buna CB 10 30 30 30 30 ZnO RS 5 5 5 5 Stearic acid 2 2 2 2 Naftolen ZD 3 3 3 3 Vulkanox 4010NA 2.5 2.52.5 2.5 Vulkanox HS 1.5 1.51.5 1.5 Protector G35 Vulkacit MOZ 1.43 C - 1.72 D - - 1.76 M - - - 1.5 Sulfur 1.5 0.8 0.8 0.8 Reversion:
max (max+60')(~) 32.0 15.8 20.6 23.8 max mln at 170C vulcanization temperature .
In a blend of NR and polybutadiene, mixtures 70 and 72 show a distinct reduction in reversion where N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra- and oligosulfides are used instead of a semi-EV-system (mixture 69).

132~805 EXAMPL _ Crosslinking of 50% epoxidized N 220-filled natural rubber (ENR 50) with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra- and oligosulfide ZnO RS 5 5 5 Stearic acid 2 2 2 Vulkanox HS 2 2 2 Vulkacit MOZ 2.4 Vulkacit Thiuram 1.6 C - 4.6 M - - 4.0 Sulfur 0.3 0.3 0.3 Reversion:
max (max+60')(%) 6.7 0.0 0.0 max min at 150C vulcanization temperature Vulcanizate data at 150C, t 95%
Tensile strength 18.7 23.9 24.6 Modulus 300% 18.0 18.4 18.9 Tear propagation strength 12 14 12 Shore hardness 75 76 78 For the same modulus value at 300~ elongation and considerably increased tear resistance, the replacement of a conventional accelerator (mixture 73) by N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra and oligosulfides (mixtures 74 and 75) produces an additional improvement in reversion.

~ - 36 -1325~05 Effect of Vulkalent E in sulfur-free NR crosslinking of N220- and N220/filica-filled NR with N,N'-substituted , bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides RSS 1, ML(1+4)=70-80100 100100100 100 100 Ultrasil VN 3 Gran. - - - 25 25 25 ZnO RS 5 5 5 5 5 5 Stearic ac,id 2 2 2 2 2 2 Naftolen ZD 3 3 3 3 3 3 Vulkanox 4010NA 2.52.5 2.52.52 5 2.5 Vulkanox HS 1.51.5 1.51.51.5 1.5 Protector G35 Vulkacit MOZ 1.43 - - 1.43 C - 3.79 3.79 - 2.84 2.84 Vulkalent E - - 3.2 - - 2.4 Sulfur 1.5 - - 1.5 Reversion:
Dmax D(max+60 )(%) 32.5 4.1 4.5 47.8 5.4 5.5 Dmin max at 170C vulcanization temperature tI 170C, mins. 4.2 2.8 4.6 4.7 3.0 4.7 :

In N220- and N220/silica-filled NR -rosslinked with C, the addition of Vulkalent E produces the desired extension of the incubation time without any deterioration in reversion.

132~80~

Retarding effect of Vulkalent E on N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra- and oligosulfide-vulcanized N220-filled NR mixtures RSS 1, ML(1+4)=70-80100 100 100 100 100 ZnO RS 5 5 5 5 5 Stearic acid 2 2 2 2 2 Naftolen ZD 3 3 3 3 3 Vulkanox 9010NA 2.5 2.5 2.5 2.5 2.5 Vulkanox HS 1.5 1.5 1.5 1.5 1.5 Protector G35 Vulkacit MOZ 1.43 B -1.66 1.66 - -M - - -1.55 1.55 Sulfur 1.50.8 0.80.8 0.8 Vulkalent E - - 1.2 - 1.2 tI (mins.) at 170C3.83.0 4.42.9 4.1 Vulcanizate data at 170C, t95~
Modulus value 300~ 10.6 10.2 11.5 10.6 11.0 The addition of Vulkalent E in B- and M-accelerated mixtures ~mixtures 84 and 86) produces an increase in the incubation time tI beyond the level of the mixture conventionally accelerated with MOZ (mixture 82).
.

132580~

N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides with addition of Vulkalent E in N220-filled NR as a function of temperature RSS 1, ML(1+4)=70-80100100 100 ZnO RS 5 5 5 Stearic acid 2 2 2 Naftolen ZD 3 3 3 Protector G35 Vulkanox 4010NA 2.5 2.5 2.5 Vulkanox HS 1.5 1.5 1.5 Vulkacit MOZ 1.43 - -B -1.66 1.66 Vulkalent E - - 1.2 Sulfur 1.5 0.8 0.8 Reversion:
max (max+60') max min at test temperature 145C 7.9 0.0 0.0 1 160C 25.6 0'0 1.9 170C 30.9 0.4 3.6 180C 39.1 2.6 5.5 Example 25 shows a pronounced insensitivity to temperature of reversion with pure N,N'-substituted bis-~2,4-diamino-s-triazin-6-yl)-tetrasulfide acceleration (mixture 88) and also with addition of Vulkalent E (mixture 89) compared with conventional acceleration (mixture 87).

13258~5 Effect of Vulkalent E on N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide- and oligosulfide-crosslinked NR filled with N220/silica RSS 1, ML(1+4)=70-80100100 100100 100 Ultrasil VN 3 Gran.25 25 25 25 25 ZnO RS 5 5 5 5 5 Stearic acid 2 2 2 2 2 Naftolen ZD 3 3 3 3 3 Vulkanox 4010NA 2.5 2.5 2.52.5 2.5 Vulkanox HS 1.5 1.5 1.51.5 1.5 Protector G35 Vulkacit MOZ 1.43 D - 3.5 3.5 M -- - 3.0 3.0 Vulkalent E -- 1.2 - 1.2 Sulfur 1.50.8 0.8 0.8 0.8 Scorch at 130C (mins.)29.5 15.0 28.5 16.5 29.0 Scorch at 170C (mins.)4.5 3.4 4.4 3.7 4.8 Where N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides and oligosulfides (mixtures 92 and 94) are used for acceleration, scorch behavior comparable with MOZ can be obtained with Vulkalent E.

. .
:. , 132~8~5 Use of N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide in combination with Si 69 with and without Vulkalent E in N220/VN3-filled NR

RSS 1, ML(1+4)=70-80 100100100100100 Ultrasil VN3 Gran. 2525 25 25 25 Si 69 3.75 3.75 3-75 3-75 3-75 ZnO RS , 55 5 5 5 Stearic acid 22 2 2 2 Naftolen ZD 33 3 3 3 Vulkanox 4010NA 2.52.52.52.52.5 Vulkanox HS 1.51.51.51.51.5 Protector G35 Vulkacit MOZ 1.43 - - - -B -2.22.2 1.66 1.66 Vullcalent E - - 1.6 - 1.2 Sulfur 1.5 - - 0.8 0.8 Reversion: -D -D 19.6 0.0 0.0 0.0 0.0 max min at 170C vulcanization temperature tI at 170~C (mins.) 4.64.25.7 4.2 5.2 Where N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfides are used together with Si 69, reversion-free mixtures are obtained both with and without sulfur (mixtures 96,98) as against conventional acceleration with silane (mixture 95). In this case, too, the addition of Vulkalent E lengthens the scorch time without recurrence of reversion (mixtures 97 and 99).

1325~

Crosslinking of N220/silica-filled NR with N,N'-substituted bis-(2,4-diamino-s-triaizn-6-yl)-tetrasulfide without sulfur Ultrasil VN3 Gran.25 25 25 25 25 25 25 ZnO RS 5 5 5 5 5 5 5 Stearic acid 2 2 2 2 2 2 2 Naftolen ZD 3 3 3 3 3 3 3 Vulkanox 4010NA 2.5 2.5 2.52.5 2.5 2.5 2.5 Vulkanox HS 1.5 1.5 1.51.5 1.5 1.5 1.5 Protector G35 Vulkacit MOZ 1.43 Sulfur 1.5 - ~ - - - -Reversion:
max (max+60 )(~) D -D . 44.7 3.2 2.01.3 3.1 2.8 2.6 max mln at 170C vulcanization temperature Vulcanizate data (t 95~) at 170C
Modulus 300~ 4.9 2.6 4.45.8 6.8 7.8 8.8 Sulfur-free crosslinking with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide in natural rubber filled with carbon black and silica suppresses reversion and at the sa~e time produces a concentration-dependent increase in modulus.
, .

132~80~

Crosslinking of silica-filled NR with N, N'-substituted bis-(2, 4-diamino-s-triazin-6-yl)-tetrasulfide Ultrasil VN 3 Gran. 50 50 ZnO RS 5 5 Stearic acid 2 2 Naftolen ZD 3 3 Vulkanox 4010NA 2.52.5 Vulkanox ~S 1.51.5 Protector G35 Vulcacit MOZ 1.43 Sulfur 1.5 :,.
max (max+60 )(%) 33.07.8 max min at 170C vulcanization temperature Vulcanizate data (t95~) at 170C
Modulus 300% 2.74.3 Sulfur-free crosslinking with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide in silica-filled natural rubber leads to a substantially reduction in reversion and at the same time to an increase in the - modulus value at 300~ elongation.

. .

13258~5 Acceleration of N220/silica-filled NR with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide Ultrasil VN3 Gran. 25 25 25 25 25 25 25 ZnO RS 5 5 5 5 5 5 5 Stearic acid 2 2 2 2 2 2 2 Naftolen ZD 3 3 3 3 3 3 3 Vulkanox 4010NA 2.52.52.5 2.52.5 2.5 2.5 Vulkanox HS 1.51.51.5 1.51.5 1.5 1.5 Protector G35 Vulkacit MOZ 1.43 - - - - - -Sulfur 1.5 0.51 0.76 1.02 1.27 1.53 1.79 Reversion:
max (max+60')(%) 44.73.21.7 0 0 0.8 1.7 ; max mln at 170C vulcanization temperature Vulcanizate data (t95%) at 170VC
Modulus at 300% 3.63r55 5 7.08.3 9.2 9.8 The sulfur vulcanization of N220/silica-filled NR with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra-sulfide reduces reversion to 0% and produces a marked increase in the modulus value.

132~80~

Acceleration of silica-filled NR with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide Ultrasil VN3 Gran.50 50 ZnO RS 5 5 Stearic acid 2 2 Naftolen ZD 3 3 Vulkanox 4010NA 2.5 2.5 Vulkanox HS 1.5 1.5 Proteetor G 35 Vulkacit MOZ 1.43 Sulfur 1.5 1.79 Reversion:
max (max+60')(%)33 0 4 5 max min at 170C vulcanization temperature Vuleanizate data (t95%) at 170C
Modulus 300% 2.7 ,5.3 The sulfur vuleanization of siliea-filled NR with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetra-sulfide is possible with virtually no reversion and produees an increase in the modulus value at 300~.

.

:

\

132~80~

Acceleration of N220/silica-filled NR with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide in the presence of Si 69 Ultrasil VN3 Gran.25 25 25 Si 69 3.75 3.75 3.75 ZnO RS 5 5 5 Stearic ac,id 2 2 2 Naftolen ZD 3 3 3 Vulkanox 4010NA 2.5 2.5 2.5 Vulkanox HS 1.5 1.5 1.5 Protector G35 Vulkacit MOZ 1.43 - -Sulfur 1.50.49 0.7q :
Reversion:
max (max+60 )(%)18.1 0 0 max min at 170C vulcanization temperature Vulcanizate data (t95~) at 170C
Modulus 100~ 1.4 1.6 2.4 Modulus 200~ 3.5 4.6 7.3 Modulus 300% 7.1 9.5 13.9 ... .
~',' Acceleration with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide in the presence of Si 69 enables reversion to be returned to 0~ for a considerable - increase in the modulus values.
:, `:

132~5 Acceleration of silica-filled NR with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide in the presence of Si 69 Ultrasil VN3 Gran. 50 50 50 50 Si 69 7.5 7.5 7.57.5 ZnO RS 5 5 5 5 Stearic acid 2 2 2 2 Naftolen ~D 3 3 3 3 Vulkanox 4010NA 2.5 2.5 2.52.5 Vulkanox HS 1.5 1.5 1.51.5 Protector G35 Vulkacit MOZ 1.43 Sulfur 1.50.49 0.74 0.99 Reversion:
max (max+60 )(%)16.6 0 0 0 max min at 170C vulcanization temperature Vulcanizate data (t95~) at 170C
Modulus value 100%1.5 1.7 2.53.2 Modulus value 200%3.4 4.3 6.68.3 Modulus value 300~6.3 8.2 12.3 15.0 Even with pure silica filling, NR is vulcanized without any reversion with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide and sulfur in the presence of Si 69, the modulus values also being very considerably increased.

132~8~5 Sulfur-free crosslinking of N220/silica-filled NR
with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide in the presence of Si 69 Ultrasil VN3 Gran. 252525 25 25 Si 69 3 75 3.75 3.75 3 75 3 75 ZnO RS 55 5 5 5 Stearic acid 22 2 2 2 Naftolen ZD 33 3 3 3 Vulkanox 4010NA 2.52.52.52.5 2.5 Vulkanox HS 1.51.51.51.5 1.5 Protector G35 Vulkacit MOZ 1.43 Sulfur 1.5 Reversion:
Dmax D(max~60 )(%) 18.1 0 0 0 max Dmin at 170C vulcanization temperature Vulcanizate data (t95%) at 170C
Modulus 200% 3.52.64.96.5 8.6 Modulus 300% 7.15.810.2 12.9 16.0 In carbon black/silica-filled natural rubber, sulfur-free crosslinking with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide, even in the presence of Si 69, prevents reversion and produces a considerable concentration-dependent increase in the modulus values.
'' .

~, , ~

132~80~

Sulfur-free crosslinking of silica-filled NR with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide in the presence of Si 69 Ultrasil VN3 Gran. 50 50 50 50 50 Si 69 7.5 7.5 7.57.5 7.5 ZnO RS 5 5 5 5 5 Stearic acid 2 2 2 2 2 Naftolen Z,D 3 3 3 3 3 Vulkanox 4010NA 2.5 2.5 2.52.5 2.5 Vulkanox HS 1.5 1.5 1.51.5 1.5 Protector G35 Vulkacit MOZ 1.43 Sulfur 1.5 Reversion:
max (max+60') (%)16.6 0 0 0 0 max min at 170C vulcanization temperature Vulcanizate data (t95~) at 170C
Modulus value 200~3.4 2.8 3.95.0 7.6 Modulus value 300%6.3 5.0 7.6 11.3 13.9 The crosslinking of silica-filled natural-rubber with N,N'-substituted bis-(2,4-diamino-s-triazin-6-yl)-tetrasulfide in the presence of Si 69 again prevents reversion and also produce a considerable increase in the modulus values.

~ - 49 -

Claims (37)

1. A compound corresponding to the general formula:

(I) wherein:
R1 represents H;
R2 represents a group selected from H, benzyl, C1-8 alkyl, allyl, 2-hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl, C3-8 cycloalkyl and C3-8 cycloalkyl substituted by from 1 to 3 methyl groups; and R3 and R4, independently, represent a group as defined above for R2 with the exception of H and benzyl; or R3 and R4, when taken together, represent a group selected from C4-6 alkylene and -(CH2CHX)2Y, wherein X represents H or -CH3 and Y represent O or S; or a mixture of compounds corresponding to the general formula:
(II) wherein R1 to R4 are as defined above, and Sx represents an average statistical chain length of x = 4;
with the exception of the compound bis-(2-ethylamino-4-diethylamino-s-triazin-6-yl)-tetrasulfide.

2. A compound or mixture according to claim 1, wherein R2 represents a group selected from H, ethyl, n-propyl, isopropyl, n-butyl and cyclohexyl, and R3 and R4, independently, represent a group selected from ethyl, n-propyl, isopropyl and isobutyl.

3. Bis-(2-ethylamino-4-di-isopropylamino-s-triazin-6-yl)-tetrasulfide.

4. Bis-(2-n-butylamino-4-diethylamino-s-triazin-6-yl)-tetrasulfide.

5. Bis-(2-isopropylamino-4-di-isopropylamino-s-triazin-6-yl)-tetrasulfide.

6. Bis-(2-ethylamino-4-di-isobutylamino-s-triazin-6-yl)-tetrasulfide.

7. Bis-(2-ethylamino-4-di-n-propylamino-s-triazin-6-yl)-tetrasulfide.

8. Bis-(2-n-propylamino-4-diethylamino-s-triazin-6-yl)-tetrasulfide.

9. Bis-(2-n-propylamino-4-di-n-propylamino-s-triazin-6-yl)-tetrasulfide.

10. Bis-(2-n-butylamino-4-di-n-propylamino-s-triazin-6-yl)-tetrasulfide.

11. Bis-(2-ethylamino-4-di-n-butylamino-s-triazin-6-yl)-tetrasulfide.

12. Bis-(2-isopopylamino-4-di-isopropylamino-s-triazin-6-yl)-oligosulfide mixture, wherein the average statistical number of sulfur atoms in the oligosulfide chain is 4.

13. Bis-(2-cyclohexylamino-4-diethylamino-s-triazin-6-yl)-oligosulfide mixture, wherein the average statistical number of sulfur atoms in the oligosulfide chain is 4.

14. Bis-(2-amino-4-diethylamino-s-triazin-6-yl)-oligosulfide mixture, wherein the average statistical number of sulfur atoms in the oligosulfide chain is 4.

15. A process for the preparation of a tetrasulfide of general formula I as defined in claim 1, wherein an aqueous alkaline solution of a corresponding N,N'-substituted-2,4-diamino-6-mercaptotrizaine is reacted in a two-phase system with a solution of S2Cl2 in an inert organic solvent in which the tetrasulfide formed is insoluble or only sparingly soluble.

16. A process as claimed in claim 15, wherein an alkali hydroxide is used in at least the stoichiometric quantity required for the reaction.

17. A process as claimed in claim 16, wherein an excess of from 1 to 20 mole % of the alkali hydroxide, based on the mercaptotriazine, is used.

18. A process as claimed in claim 16 or 17, wherein sodium or potassium hydroxide is used as the alkali hydroxide and a C5-C10 alkane or C5-C8 cycloalkane which may be substituted by 1 to 3 methyl groups, as solvent.

19. A process for the preparation of the mixture of compounds of general formula II as defined in claim 1, wherein a compound of general formula I as defined in claim 1 is disproportionated without formation of free sulfur.

20. A process as claimed in claim 19, wherein the tetrasulfide corresponding to general formula I is heated beyond its melting point.

21. A process as claimed in claim 19, wherein the tetrasulfide corresponding to general formula I is dissolved in an inert organic solvent and the disproportionation reaction is allowed to take place at a temperature between 20°C and the boiling point of the solvent.

22. A process for the preparation of the mixture of compounds of general formula II as defined in claim 1, wherein an aqueous alkaline solution of the corresponding N,N'-substituted-2,4-diamino-6-mercaptotriazine is reacted in a two-phase system with a solution of S2Cl2 in an inert solvent in which the tetrasulfide formed is soluble.

23. A process as claimed in claim 22, wherein chlorinated hydrocarbons, ethers, esters, aromatic hydrocarbons or ketones which are insoluble in water are used as the solvent.

24. A vulcanizable mixture comprising at least one natural or synthetic rubber and 0.2 to 15 parts by weight per 100 parts by weight of the rubber of a compound or a mixture of compounds as defined in any one of claims 1 to 14.

25. A vulcanizable mixture according to claim 24, comprising 0.3 to 8 parts by weight per 100 parts by weight of the rubber of said compound or mixture of compounds.

26. A vulcanizable mixture according to claim 25, which is free of sulfur.

27. A vulcanizable mixture comprising at least one natural or synthetic rubber and 0.01 to 10 parts by weight per 100 parts by weight of the rubber of a compound or a mixture of compounds as defined in any one of claims 1 to 14, wherein the mixture comprises 0.1 to 10 parts sulfur per 100 parts of the rubber.

28. A vulcanizable mixture according to claim 27, comprising 0.1 to 5 parts by weight per 100 parts by weight of the rubber of said compound or mixture of compounds.

29. A vulcanizable mixture according to claim 27, wherein the molar ratio of said compound or mixture of compounds to the sulfur (S8) is 1:0.5-1.5.

30. A vulcanizable mixture according to claim 27, further comprising N-phenyl-N-(trichloromethyl-sulfenyl)benzenesulfonamide as a retarder, wherein the molar ratio of said compound or said mixture of compounds to said retarder is 1:0.5-1.5.

31. A vulcanizable mixture according to claim 30, wherein the molar ratio is 1:0.8-1.2.

32. A vulcanizable mixture according to any one of claims 28 to 31, comprising 0.5 to 8 parts sulfur per 100 parts of the rubber.

33. A vulcanizable mixture according to any one of claims 25, 26 or 28 to 31, comprising a filler consisting of silica.

34. A vulcanizable mixture according to any one of claims 25, 26 or 28 to 31, comprising a filler consisting of carbon black and more than 15 parts silica per 100 parts of the rubber.

35. A process for vulcanizing a vulcanizable mixture comprising at least one natural or synthetic rubber, comprising using as a vulcanization accelerator a compound or a mixture of compounds as defined in any one of claims 1 to 14.

36. A process according to claim 35, wherein the vulcanizable mixture comprises sulfur.

37. A process according to claim 35, wherein the vulcanizable mixture is sulfur-free.