DE1914175C3 - Vulcanizable compounds - Google Patents

Description

characterized in that the masses Additionally

6. 0.1 to 1 part by weight of a guanidine and

7. Contain another dithiocarbamate accelerator.

2. Compounds according to claim 1, characterized in that they are used as a dithiocarbamate accelerator Contain metal and / or ammonium salts of N-disubstituted dithiocarbamates, the 3 » Substituents are alkyl, alkylene, cycloalkyl and / or aryl radicals.

3. Compounds according to claim 1 or 2, characterized in that the dithiocarbamate accelerator by the organic radicals substituted on nitrogen and / or by the salt-like differentiate between bound metal and organic ammonium ions.

The invention relates to vulcanizable masses of isobuiylene-isoprene copolymers (IIR), ethylene-propylene-diene terpolymers (EPDM) or their mixtures, using sulfur, a dithiocarbamate accelerator and a thiazole accelerator as a vulcanizing agent.

Of the elastomers used in technology, copolymers are made from isobutylene and isoprene (IIR) and the terpolymer made from ethylene, propylene and a diene with non-conjugated double bonds (EPDM) has a low content of reactive double bonds that are accessible to crosslinking are. IIR usually has a degree of unsaturation between 1 and 3 mole percent, EPDM is currently with a degree of unsaturation between 0.6 and 2.5 mole percent known. Styrene-butadiene rubber has comparatively an unsaturation level of about 80 mole percent. Because of the low proportion of unsaturated Bonds, the rate of vulcanization of IIR and EPDM is more effective even when used Ultra accelerator undesirably low.

Various types of accelerator are used to vulcanize such rubbers with a low degree of unsaturation known. This is how a sulfur vulcanization with an accelerator system becomes one Thiazole derivative and a metal dithiocarbamate, possibly in combination with an accelerator from the Class of thiuram sulfides.

The so-called quinone vulcanization uses a crosslinking system made from quinone dioxime or p, p'-dibenzoylquinone dioxime and lead oxides, possibly with the addition of an accelerator of the thiazole group.

Furthermore, the resin vulcanization takes place with a system of dimethylolphenol resins and a halogen-containing one Activator.

In the known processes, vulcanization with the systems mentioned is ^{carried out at temperatures of over 140 °} C. and mostly in an autoclave in order to take place within economically justifiable times. Only the quinone vulcanization runs fast enough to be used, for example, in cable production in a continuous vulcanization process, but also at high temperatures.

The object of the invention is to create a vulcanization system and an accelerator which make it possible to Vulcanize rubbers with a low degree of unsaturation at moderately high temperatures.

The subject of the invention are masses that can be vulcanized in hot air or a salt bath at temperatures of 70 to 120 ^{° C., consisting of:}

1. Isobutylene - isoprene copolymers or ethylene - propylene - diene terpolymers or their mixtures,

2. 0.5 to 2 parts by weight, based on 100 parts by weight of polymer, sulfur,

3. 0.5 to 4 parts by weight, based on 100 parts by weight of polymer, of a dithiocarbamate accelerator,

4. 0.1 to 1 part by weight, based on 100 parts by weight of polymer, of a thiazole,

5. as well as, if applicable, reinforcing fillers, plasticizers, Extender oils and stabilizers,

characterized in that the masses additionally

6. 0.1 to 1 part by weight of a guanidine and

7. Contain another dithiocarbamate accelerator.

Dithiocarbamates within the meaning of the invention are:

Zinc ethyl phenyl dithiocarbamate,

Zinc dibutyl dithiocarbamate,

Zinc dimethyl dithjocarbamate,

Zinc diethyl dithiocarbamate,

Copper dimethyl dithiocarbamate,

Cadmium diethyl dithiocarbamate,

Tellurium diethyl dithiocarbamate,

Sodium cyclohexylethyl dithiocarbamate,

Zinc-N-pentamethylene-dithiocarbamate,

Lead dimethyl dithiocarbamate,

N-pentamethylene ammonium pentamethylene

dithiocarbamate.
Are guanidine within the meaning of the invention

Diphenylguanidine,

Orthotolyl biguanide,

Di-o-tolylguanidine et al
Thiazoles within the meaning of the invention are

2-mercaptobenzothiazole,

Benzothiazyl disulfide,

Dibenzothiazyl disulfide and their reaction products.

It is particularly advantageous to use such dithiocarbamate accelerators to use which differ by the organic radicals substituted on nitrogen and / or by the salt-like bonded metal or organic ammonium ions.

For example, leads to the use of a vulcanization accelerator consisting of zinc äthylphenyldithiocarbamat, zinc dibutyldithiocarbamate, Diphenylgoanidin and 2-mercaptobenzothiazole in the presence of sulfur in 24 hours at 80 ⁰ C only, even in a butyl rubber with only 1 mole percent unsaturation to full vulcanization. The scorch time can be regulated by varying the proportions of the accelerators in such a range that the entire vulcanization system can be mixed in in the internal mixer (stamp kneader, Banbury mixer)

A particular advantage of the vulcanization according to the invention at temperatures below 100 ° C is that that no superheated steam has to be used, no pressure-resistant vulcanization kettles are required and evenly and extremely gently vulcanized and even with thicker layers largely tension-free articles can be obtained. On the other hand, it is quite possible with the said Vulcanization system z. B. to vulcanize profiles in a salt bath (LMC process), since the VuI-kacisierungsfrequenz very quickly in the process according to the invention at high temperatures The vulcanization is preferably carried out in hot air

Advantageously, 0.5 to 4.0 parts by weight of dithiocarbamates, 0.1 to 1.0 part by weight of a thiazole, 0.1 to 1.0 part by weight of a guanidine and 0.5 to 2.0 parts by weight of sulfur are used per 100 parts by weight of rubber preferably, the vulcanization is conducted at temperatures of 70 to 120 ⁰ C, in particular from 75 to 90 ⁰ C, carried out

In a manner known per se, reinforcing fillers, plasticizers, extender oils, light stabilizers, Anti-aging agents and the like can be added.

The combination of vulcanization accelerators for carrying out the method according to the invention ίο contains a dithiocarbamate and a thiazole and contains in addition to the dithiocarbamate and the thiazole, a guanidine and another dithiocarbamate

It preferably contains metal and / or ammonium salts of N-disubstituted dithiocarbamates, where the substituents are alkyl, alkylene, cycloalkyl and / or aryl radicals. In particular, the mentioned dithiocarbamates, guanidines and Thiazoles into consideration

In the following examples, the invention is illustrated by means of working examples. The unnamed Numbers indicate parts by weight.

example 1

Basic recipe

HR (1 mole percent unsaturation) 100.0

FEF carbon black 50.0

HAF carbon black 35.0

SRF carbon black 30.0

ZnO, active 5.0

Light protection wax '. 3.0

Stearic acid 1.0

N-phenyl-N'-isopropyl-p-phenylenediamine .. 1.0

Extender Oil 10.0

Polyethylene wax 8.0

Accelerator system B. C. D. B. F. A. 0.7 0.7 0.7 - - Zinc ethylphenyldithiocarbamate 0.7 3.0 3.0 3.0 1.5 1.5 Zinc dibutyldithiocarbamate 3.0 - - 1.5 - —— N-pentamethylene ammonium penta- - methylenedithiocarbamate 0.5 0.5 0.5 1.0 1.5 2-mercaptobenzothiazole 0.5 - - - 0.5 ¹ ' Dibenzothiazyl disulfide - 0.5 - 0.3 - 0.5 Diphenylguanidine 1.2 1.2 1.2 1.5 1.2 1.2 sulfur 1.2 6'00 " 9'00 " 5'00 " 8'45 " 12'30 " Mooney t ₅ 4'30 " 10'30 " 18'35 " 8'45 " 34Ί5 " 26'00 " Mooney I ₃₅ 7'40 " 80 80 80 80 160 Vulcanization ^{temperature (0} C) 80 24 36 16 72 0.33 Vulcanization time (h) 24 68 62 69 65 70 Shore A 69 80 62 86 81 86 Tear strength (kp / cm *) 82 650 600 670 725 650
CC Elongation at break (%) 525 40 40 45 27 56 Unusual value at 300% elongation 60

Ii

Example 1 shows that the rate of vulcanization can be varied within wide limits by varying the vulcanization system accordingly. Is missing a component such as the guanidine in Example 1 C, or is just a dithiocarbamate, as in Example IE and 1F, are used, they are lengthened with the same Temperature, the vulcanization times significantly, or higher vulcanization temperatures are required, or at temperatures below 100 ° C. there is no vulcanization at all, as in the example 1F, where only after 96 hours at 80 ° C a tear strength of 14.5 kp / cm * is available

Example 2

Example 2 shows the comparison of a mixture with conventional acceleration (2 A) with a Mixture with acceleration according to the invention (Example 2Q. Example 2B shows a compromise solution between the two vulcanization systems, the leads to a product with inadequate mechanical values despite relatively favorable Mooney values. Basic recipe

HR (1 mole percent unsaturation) 100.0

SRF carbon black 30.0

FEF carbon black 30.0

HAF carbon black 20.0

Kaolin _r 50.0

ZnO, active «5.0

Light protection wax 3.0

N-phenyl-N'-isopropyl-p-phenylenediamine .. 1.0

Extender Oil 10.0

Accelerator system B. C. A. Tetramethylene thiuram 1.0 disulfide - 0.5 2-mercaptobenzothiazole 0.5 - - Zinc diethyldithio 0.3 carbamate 0.7 0.7 Zinc ethylphenyldithio- - carbamate 3.0 3.0 Zinc dibutyldithio - carbamate 0.5 0.5 Diphenylguanidine - 1.2 1.2 sulfur 1.5 7Ί0 " 8.45 " Mooney t _s (min) 12'30 " 16'45 " 14'00 " Mooney t «(min) 21'00 " 80 80 Vulcanization temperature 145 rature ( ⁰ Q 36 24 Vulcanization time (h) 1 53 63 Shore A 64 37 74 Tear strength (kp / cm *) 82 440 550 Elongation at break (%) 520 25th 28 Voltage value at 49

300% elongation (kp / cm ^a )

Example 3

Example 3 compares a customary acceleration of EPDM (Example 3 A and 3B) with tetramethylthiuram disulfide, zinc diethyldithiocarbamate, 2-mercaptobenzothiazole and sulfur using the vulcanization process according to the invention. The usual acceleration at 160 ° C. results in optimum vulcanization after 20 minutes. If one tries to carry out without pressure in the hot-air vulcanization at 8O ⁰ C, so no optimclen cure properties are achieved even after 96 hours. Another disadvantage of the known process is that the system used in Examples 3 A and 3 B shows severe sulfur bloom after 24 hours.

Examples 3 C to 3 F show that by varying the proportions of the system according to the invention the curing and curing times can be varied accordingly. Missing a component like that Diphenylguanidine in Example 3 G, the vulcanization time increases to the values of the conventional one Systems.

Vulcanization system ABCDEFG

Tetramethylthiuram disulfide 1.0 1.0 0.5 0.5 0.5 0.5 0.5 2-mercaptobenzothiazole 0.5 0.5 - - - - - Zinc diethyl dithiocarbamate 1.5 1.5 3.0 3.0 3.0 3.0 3.0 Zinc dibutyldithiocarbamate - - 0.7 0.7 0.7 0.7 0.3 Zinc ethylphenylditbiocarbamate - - 1.0 - - - - N-pentamethylene ammonium penta- - - methylenedithiocarbamate 0.5 0.5 0.5 1.2 - Diphenylguanidine - - - 1.0 - - - Zinc N-pentamethylene dithiocarbamate - - 1.2 1.2 * 1.2 1.2 1.2 sulfur 1.5 1.5 6'20 " 730 " 8'00 " 8Ί5 " 15'00 " Mooney t ₅ 22'00 " 22'00 " 13'35 " ll'30 " 14'40 " 20'30 " 37'00 " Mooney tss 35'45 " 35'45 " 80 80 80 80 80 Vulcanization temperature ( ⁰ Q 160 80 36 16 24 48 96 Vulcanization time (h) 0.33 96 59 61 61 59 56 Shore A 61 54 - 95 120 118 107 81 Tear strength (kp / cm *) 118 90 550 650 40 520 540 Elongation at break (%) 380 415 66 65 60 71 57 Stress value at 300% elongation (kp / cm *) 83 70

Claims (5)

Patent claims: 1. In hot air or a salt bath at temperatures of 70 to 120 ⁰ C vulcanizable masses, consisting of: 1. Isoburylene-isoprene mixed polymers or Ethylene-propylene-diene terpolymers or their mixtures, 2. 0.5 to 2 parts by weight, based on 100 parts by weight of polymer, sulfur, 3. 0.5 to 4 parts by weight, based on 100 parts by weight Polymer, a dithio-carbamate accelerator, 4. 0.1 to 1 part by weight, based on 100 parts by weight Polymer, of a thiazole, 5. and, if applicable, 'reinforcing fillers, Plasticizers, extender oils and stabilizers ^gates ' _ao