DE1769268C3 - Heat-vulcanizable compound - Google Patents

Description

κ Il

N-C

20th

where .v is an integer from 1 to 4, and

b) 0.1 to 5 parts by weight of a thiuram sulfide or a melallodithiocarbamal contains.

The invention relates to a heat-vulcanizable mass. Consisting of (A)

a) an ethylene-propylene-diene terpolymer or

b) butyl rubber,

or mixtures of a) and b) with other sulfur-vulcanizable rubbers, (B) sulfur. Zinc oxide and other usual additives, which is characterized by this. that the mass to accelerate vulcanization
a) 0.1 to 5 parts by weight c. based on 100 parts by weight of A, of a bis (morpholinothiocarbonyl) sulfide of the general formula

s! I

N-C-S,

45

wherein χ is an integer from 1 to 4, and b) 0.1 to 5 parts by weight of a thiuram sulfide or

of a metal dithiocarbamate. Some of the newer hydrocarbon elastomers, particularly ethylene propylene rubber and butyl rubber, have been modified to contain small amounts of unsaturation so that they can be vulcanized using a sulfur vulcanization system. In the case of ethylene propylene rubber, this modification is generally carried out by co-reacting a non-conjugated diene e.g. B. dicyclopentadiene. 1,5-cyclo ^ o ocladicn, norbornadiene u. Like. Achieved. In this regard, diene-modified ethylene propylene rubber (LiPDM) is of particular importance. Butyl rubber inherently contains small amounts of unsaturation which originate from the isoprene unit in the polymer structure. Neither of these elastomers was suitable for the usual vulcanization systems because of the low degree of unsettlingness they had compared to other, more unsaturated all-purpose elastomers, e.g. B. Siyro-butadiene-C opolymers (SBR) or Naturkar.chuK contain

The sulfur vulcanization of (EPDM) and butyl rubber was usually done with the help of zinc oxvd and organic accelerators. The more effective primary accelerators are either Th.-urammono-, di- or -tetrasulfide or Metalld.thiocarbamate. A thiazole. z. B. mercaptobenzothiazole, is normally required as a secondary accelerator to achieve satisfactory cure speeds. . . ....

The development of satisfactory vulcanization systems Door EPDM was mainly due to the tendency of the elastomer to vulcanize prematurely (i.e. for so-called scorching) and the various components or their reaction products to migrate to the surface of the pre-vulcanizate and the vulcanizate. One usually used system for EPDM. the tetramethylthiuram disulfide. Mercaptobenzothiazole and sulfur contains leads to sufficient safety during processing (scorch resistance), in the case of hot-hardened Vulcanizates, however, occur strong efflorescence. Attempts to remedy this disadvantage have to a reduced security during processing. B. one half of the Tctramelhylthiuramdisulfids replaced by dipentamethylene thiuram tetrasulfide and the concentration of mercapiobenzothiazole increased, the blooming is decreased and the modulus increased, the scorch resistance on the other hand, is greatly reduced. Other systems have been developed. in which the tendency to bloom is reduced, but the scorch resistance is at the same time the preparation low. Similar difficulties, including slow curing speed, occur with butyl rubber. It exists! therefore a need for a sulfur vulcanization system Door EPDM and butyl rubber, the safe processing, good curing speed and ensures a good hardening condition and does not bloom. The invention aims at such an improved one Vulcanization system.

Surprisingly, it has been found that more vulcanizable Rubber with a low degree of unsaturation safe and with good curing speed to be satisfactory, non-blooming Vulcanizates sulfur vulcanizicrl can be if the vulcanization in the presence of an organic Accelerator composition of a combination of a bismorpholinothiocarbonyl sulfide and one Thiuram sulfide or a metal dithiocarbamal is carried out.

Thiuram sulfides and metal dialkyldithiocarbamals have been known for many years and have been used extensively in vulcanization systems for many types of rubbers. Bismorpholinothiocarbonyl sulfides. as described above are not effective accelerators for FPDM or butyl rubber when used alone! will. as they work very slowly and result in a low degree of hardening. It is therefore very surprising that it is with the accelerator system according to the invention. which is obtained by combining a thiuram sulfide or a Melalldialkyldithiocarbamal with a bismorpholinothiocarbonyl sulfide, is possible. achieve a high degree of hardness / u without compromising safe processing! The

3 4

The system is unique in that no other vapors have been found in open operation, through pressure hardening with bisthiocarbonyl sulfide, which lead to the liquid hardening media ("LCM") and the like, with the same or a similar result. Under the usual conditions, which are alluded to for these elastomers, until (2,6-dimethylmornholinothiocarbonyl sulfide are used, vulcanized. The concenyl) disulfide, an analogous compound, is moderately ineffective in the ratio of bisfmorpholinothiocarbonyl sulfide. The diene content of the th range of properties of the Vulkanisa's or ethylene-propylene-diene terpolymer used according to the invention also comes from the copolymerization with dicyclo- denene thiuram sulfide or Meiallalkyldhhiocarbamat. pentadiene or 1.5 cyclooctadiene. , ₀ When using tetramethylthiuram disulfide and Thiuram mono- suitable according to the invention. bis (Morpholinothiocarbonyl) disulfide as accelerator di and tetrasulfides and Metalldialkyldithiocarb- gerkombination lead more than about 0.75 parts amates include, for example, lower alkyl, mono-tetramethylthiuram disulfide with 1.5 parts bis (Morcyclic aryl lower alkyl, aryl and cyclic Alkylenepholinothiocarbonyl) disulfide to form reinforced Austhiuramulfide and -dithiocarbamate like: i ₅ bloom. Fulls of 2.0 parts of bis (morpholinothiocarbo-tetramethylthiuram sulfide, nyl) disulfide or more with 0.75 parts of tetramethyl tetramethylthiuram monosulfide are used, the hardening tetraethylthiuram disulfide, hardening rate is advantageously slowed down, and a tetramethylthiurammonosulfide hardening rate is advantageously achieved. Less ^than Dipeniamethylenthiuramtetrasulfid ²⁰ ^ ^{5 parts} usually lead to increased off Cyclohexamelhylenthiuramdisulfid. blooming. It can thus be seen that the concentration is diisopropylthiuram disulfide. J ^CDER component of the inventive Accelerat-Phcnyläthylthiuramdisulfid, nigcrsystems depending on the above-mentioned zinc dibutyldithiocarbamate factors and also by the respective application zinc pentamethylene dithiocarbamate ² 5 & ^{ebiel 'rur to} be ^{used, the} vulcanizate. Bismuth dimethyldithiocarbamate. ⁷ - ^{Bureau of tires, wire and} cable sheaths. Nickel dibutyl dithiocarbamate tubing, belts, other mechanical goods. Pro-copper-dimethyl-dithiocarbamate ^{products in the} cell structure and the like, fluctuates. A general selenium diethyl dithiocarbamate effective concentration range door every compound lead dimethyl dithiocarbamate. 3 ° ^{nenle beträ} S ^{l equipped only} ° - dithiocarbamate chewing ^{selenium-dimethyl-'to} 5.0 parts to 100 parts. chuk.

Tell-Jimethyl-dithiocarbamai, Other commonly used compounding

Tell diethyl dithiocarbamate components, e.g. B. Soot. mineral fillers. Clays.

Cadmium diethyl dithiocarbamate. Processing oils, soaps, waxes and the like can be used

Zinc dibenzyl dithiocarbamate 35 mass as required to achieve certain properties

Zinc diethyl dithiocarbamate. shafts are added. The crowds can get on

common rubber or plastics processing

The sulfur vulcanization system always contains devices gemis ^ 'u, molded, extruded or in

Sulfur and zinc oxide and often a secondary one of the many known to the rubber expert

accelerator, e.g. B. a thiazole. The used ₄₀ ways are processed.

The amount of sulfur depends on the particular vulcanization properties desired. The following examples illustrate the invention. Generally it is used without being limiting. Parts refer to the weight by increasing the sulfur concentration.
Scorch resistance reduced and the degree of hardening increased. The usable range for sulfur ₄₅ Example 1
in general, about 0.5 to 3.0 parts / 100 parts protrudes four EPDM rubber compounds were rubber as follows, but can be used for some purposes as follows:
have high value like 5 or more pieces.

Zinc oxide (or zinc soaps, e.g. zinc stcarate) becomes a base

always used in the sulfur vulcanization system, ₅₀ hydrocarbon rubber

that; contains the accelerator according to the invention. 100 parts by weight EPDM and

The concentration of zinc oxide is not critical. 50 parts by weight naphthene oil 150

provided that at least 1.0 part / 100 parts of chewing SAF carbon black 60

chuk can be used. In general, ISAF-H carbon black turns out to be 20

the use of about 3 to 5 parts of zinc oxide ₅₅ zinc oxide 5

well effective. Stearic acid 1

'Vlercaptobenzothiazole (MBT) is usually called sulfur 2

Secondary accelerator in the vulcanization of Mrrcaptobenzthiazole 1.5

FPDM and butyl rubber used. The increase

the concentration of mcrcaptobenzothiazole leads to ^ ₀

a reduction in scorch resistance. In all- Vcrbimium ·

in general, effective amounts of MBT are in the range of " ^(!)

rich from about 0.5 to 2.0 parts 100 parts rubber

Benzthiazyl disulfide (MBTS) is another common one

Secondary accelerator. the 65 accelerators in the same concentration

can be applied. Bisimorpholino 1.5 1.5

The vulcanizable compositions according to this invention tliiocarbonyl) -

can by known methods, e.g. B. mi; Water disulfide

17th

continuation Connection 0.75 C. D. A. - - 0.7 accelerator 0.75 Tetramethyl thiuram disulfide 0.75 Dipentamethylene 17.3 thiuram disulfide Vulcanization 61 29 duration at 12IC 13.7 Rise on 5 points in Minutes, T ₅ 38.3 300% modulus, 42.2 kg cm ² , at 160 ° C 63.3 15.5 44.6 hardened 48.5 miltel 20.0 50.6 after 15 minutes 52.7 48.5 75.2 after 20 minutes 79.8 very very after 60 minutes medium Well Well resistance Well iieaen expansion

The values show that EPDM when cured with the usual accelerators (A and B) ^. ■ ' very strong

268, 1

Scorch shows. The connection B leads to greater security in the processing, but has a lower degree of hardening and stronger efflorescence result. Bis (morpholinothiocarbonyl) disulfide cures too slowly to be of any practical use (Compound C) and performs to a very low degree of hardening. The combination of bis (morpholinothiocarbonyl) disulfide and Tetramethylthiuram disulfide (compound D) doubled the processing reliability of a conventional hardening system (A) and leads to a good degree of hardening and little efflorescence.

Example 2

EPDM rubber compounds were produced as follows. The components are given in parts by weight.

Basic mass

Composed of 100 parts by weight of EPDM

and 50 parts by weight of naphthene oil 150

SAF carbon black ⁶⁰

ISAF-H carbon black -0

Zinc oxide ^?

Stearic acid '

Sulfur - _

Mercaptobenzothiazole 1.5

Tetramethylthiuram disulfide 0.75

Connection uni; Ii C. I) Λ accelerator Dipene; amethylenthiuramtetra-
sulfide 0.75 1.5 Diisopropylthiuram disulfide 1.5 Phenylethylthiuramsullide 1.5 Bis (2,6-dimethylmorpholino- 1.5 thiocarbonyl sulfide Scorch time at 121 C 14.2 15th 15.9 5 points increase 11.7 in minutes, T ₅ 300% modulus, kg / cm ² hardened at 160 ^{c C.} 47.1 52.7 after 15 minutes 45.7 66.1 73.8 73.8 after 20 minutes 62.6 73.8 82.6 80.9 after 60 minutes 84.4 very bad medium good bad medium Resistance to blooming medium good

The values show that none of the different thiuram sulfides in combination with tetramethylthiuram disulfide results in a good curing system for EPDM because all of them have too much scorching and the connections bloom excessively.

Example 3

The basic material for this mass was prepared in the same way as in Example 1. The basic mass accelerator stars were added as indicated, which bislmorpholinothiocarbonyl-disulphide in Combination with other common thiuram sulfides !! contained. The accelerators used in the experiments are designated as follows:

A - tetramethylthiuram monosulfide,
B-tetramethylthiuram disulfide.
C -Tetraethylthiuram disulfide.
D tetrabutylthiuram disulfide.
E dipentamethylene thiuram tetrasulfide,
F zinc dimethyldithiocarbamate.
G zinc dibutyldithiocarbamate,
H zinc dibenzyldithiocarbamate,
1 diphenyldimethylthiuram disulfide,
I fisen-dibenzyldithiocarbamate,
K bis (mornholinothioc'4rbonyl) disulfide.

Λ Β C D F. K G HJ KL

accelerator

A 0.75 - ... ._

B - 0.75 0.75

C _. .. 0.75

D .__... 0.75 - ■ - - - -

E "- - - - - 0.75 -

F - -.- _ - - 0.75 - - -

G - - - - - - 0.75 - - ■ -

I - - - - - _____ __ o, 75 -

K 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5

Scorch time at 121 ° C

Increase by 28.5 29.0 32.0 32.0 23.5 *) 63.0 *) 14.5 *) 38.0 *) 32.0 *) 53.5 *) 33.5 *)

5 points in
Minutes, T ₅

300% modulus at
16O ⁰ C hardened

after 15 minutes 42.5 44.6 39.0 32.7 38.0 17.2 34.5 25.3 28.1 26.4 26.4 after 20 minutes 57.3 50.6 48.9 47.1 40.4 22.5 36.6 32.7 35.9 33.0 32.7 after 60 minutes 74.5 75.2 70.3 70.3 66 .8 56.2 65.0 57.3 64.7 61.9 63.3 Resistance to very, very very, very, very, very, very, very, very, very, very, very, very, very, very, very, very, very, very, very, very, very, very, very, very A very, very A very A very A very A very A very A very A very A very A very E | good good good good draw- good good /. sign- draws- draws net net net net

*) These masses were rolled again; Modulus and Scorchwcrle are therefore worse: see Compound B and E as the basis for Comparisons.

Example 3 illustrates the effective combination scorch time of 14.5 minutes shorter than that

of bis (morpholinothiocarbonyl) disulfide with different times in the series, but considerable different thiurams and dithiocarbamic acid salt- 40 longer than the scorch time of the same compound

zen of various metals. The good vulcanizate if the bis (morpholinothiocarbonyl) disulfide through

properties, processing reliability and excellent- another thiuram, e.g. B. Tetramethyl.hiuramdisul

nete resistance to blooming are open- fid, is replaced, borrowed. In the case of zinc dimethyldithiocarbamate, the

Example 4
The following base material was produced:

Butyl rubber 100

FEF carbon black 60

Naphthenic oil 40

Zinc oxide 5

Stearic acid 1

Sulfur ... 1.5

Mercaptobenzothiazole 0.5

Mixture of 33% N-methyl-N,

4-dinitrosoaniline and 67%

inert material 0.5

Using this matrix, the following compositions were tested:

ABCD E F G

component

Tetramethylthiuram disulfide KO 1.0 1.0 1.0 1.0

Dipentamethylnthiuram- '-0 2.0 2.0

tetrasulfide

continuation

ίο

component 17.9 16.7 1.0 17.6 2.0 13.9 2.0 Bisfmorpholinothiocarbonyl) - disulfide Scorch time at 132 ° C 23.6 33.6 64.0 5 points increase in 27.1 31.3 34.1 24.3 Minutes, T ₅ 35.2 38.7 43.6 36.2 300% modulus kg / cm ² at 160 ° C 38.3 43.2 48.9 39.4 hardened 38.3 42.9 32.3 46.4 27.1 40.8 - after 12.5 minutes medium medium 41.5 out 39.7 out after 25 minutes Well 47.5 draws 39.7 draws 23.2 after 50 minutes 43.9 40.4 26.7 after 75 minutes Well very good out Resistance to blooming out draws draws (Nothing)

This example shows what effect is achieved. if you have either one or the other component of the accelerator according to the invention are used separately. It also shows the effect of using it a two-component accelerator that does not use bis (morpholinothiocarbonyl) disulfide as one of its Contains components.

Claims (1)

Palent claim: Heat-vulcanizable mass, consisting of (Al a) an ethylene-propylene-diene terpolymer or b) butyl rubber, or mixtures of a) and b) with other sulfur-vulcanizable rubbers, (B) sulfur, Zinc oxide and other usual additives. characterized in that the mass to accelerate vulcanization a) 0.1 to 5 parts by weight, based on 100 parts by weight A, a bis (morpholinothiocarbonyl sulfide of the general formula