Elastomeric mass of polychloroprene sol and polychloroprene gel

An elastomeric mass of polychloroprene sol and polychloroprene gel in proportions in the range of 95:5 to 25:75% by weight in which the polychloroprene sol is free from sulphur and the polychloroprene gel used is a sulphur-containing gel with xanthate or carbamate functions has better processing characteristics than the pure sol component without the expected deterioration in the mechanical properties of the vulcanisates prepared from the mass.

This invention relates to an elastomeric mass of polychloroprene sol and 
polychloroprene gel with improved properties for practical application and 
the preparation thereof. 
Sol-gel mixtures of polychloroprenes are known. The addition of a gel 
component to the sol improves the processing properties (e.g. expansion 
after extrusion) of the rubber mixtures but impairs the mechanical 
properties of the vulcanisates, in particular their strength. 
Numerous proposals have been made for preserving the good processing 
characteristics of the sol-gel mixture without impairing the mechanical 
properties of the sol component in the mixture (U.S. Pat. No. 3,655,827, 
DE-OS No. 2,536,372, U.S. Pat. No. 4,485,216). These proposals either 
solve the problem only partly or are based on very special solutions which 
render the product uneconomical. 
The problem therefore arose of providing new sol-gel mixtures which could 
be easily processed and showed no impairment in the mechanical properties 
over a wide mixing range. 
This problem is solved according to the invention by mixing a 
sulphur-containing gel polymer carrying xanthate or carbamate functions 
with a sulphur-free sol polymer in proportions within the range of 5:95 to 
75:25, preferably 10:90 to 50:50 % by weight (based on dry polymers). 
The terms "sulphur-containing" and "sulphur-free" denote that 
polymerisation is carried out in the presence or absence of elementary 
sulphur or a conventional sulphur donor. Polymers carrying 
sulphur-containing end groups, for example due to having been prepared 
with the aid of persulphates as initiators, are therefore not regarded as 
sulphur-containing. 
The present invention thus relates to elastomeric masses of polychloroprene 
sol and polychloroprene gel in proportions within the range of 95:5 to 
25:75, preferably 90:10 to 50:50% by weight, in which the polychloroprene 
sol is sulphur-free, characterised in that the polychloroprene gel used is 
a sulphur-containing gel carrying xanthate or carbamate functions. 
It is preferred to use a polychloroprene gel for which the copolymerisation 
of chloroprene, sulphur and optionally other monomers capable of 
copolymerising with chloroprene is carried out in aqueous emulsion with 
the aid of a peroxo activator in the presence of xanthates or 
dithiocarbamates whose anions correspond to the formulae 
##STR1## 
wherein R.sub.1, R.sub.2 and R.sub.3 denote an optionally substituted 
alkyl, cycloalkyl or aryl group and 
R.sub.1 and R.sub.2 may also combine with the nitrogen atom to form a ring 
optionally containing at least one further hetero atom, 
the formation of gel being brought about by the incorporation of a cross 
linking substance and/or by a high conversion rate. 
The dithiocarbamates and xanthates are preferably used in the form of their 
ammonium or alkali metal salts, in particular their sodium or potassium 
salts. 
R.sub.1 and R.sub.2 preferably stand for C.sub.1 -C.sub.4 alkyl and R.sub.3 
preferably stands for C.sub.1 -C.sub.8 alkyl or 
2,2-(2,4-dioxapentamethylene)-butyl. 
It is preferred to use from 0.05 to 5.0% by weight, in particular from 0.1 
to 3.0% by weight of sodium dibutyl dithiocarbamate, based on the quantity 
of monomers of the gel polymers, or a corresponding molar quantity of 
another dithiocarbamate or from 0.1 to 5.0% by weight, in particular from 
0.5 to 3.0% by weight of potassium ethyl xanthate, based on the quantity 
of monomers of the gel polymer, or a corresponding molar quantity of 
another xanthate. 
The latex particles are cross linked by conventional methods either during 
polymerisation or in a cross linking stage following the stage of 
polymerisation. In the simplest case, cross linking is achieved by 
polymerisation to high conversion or, in a monomer inflow process, by 
polymerisation at high internal conversion (DE-AS No.1,248,921). 
Preparation of the gel may also be carried out by copolymerisation with 
multifunctional comonomers or the use of multifunctional comonomers in 
combination with high conversions. 
The following multifunctional comonomers may be used: divinyl benzene, 
divinyl ether, divinyl sulphone, diallyl phthalate, triallyl cyanurate, 
triallyl isocyanurate, 1,2-polybutadiene, N,N'-m-phenylene-dimaleimide, 
and triallyl trimellitate. Acrylates and methacrylates of polyfunctional 
alcohols are preferably used. Preferred polyfunctional alcohols include 
ethylene glycol, butane diol, hexane diol, polyethylene oxide diol, 
trimethylol propane, tetramethylol methane and other compounds mentioned 
in DE-AS No. 1,720,107, U.S. Pat. Nos. 3,714,296 and 3,849,519. Cross 
linking of the latex particles after polymerisation is also a possibility. 
Examples of this procedure include the methods indicated in DE-AS No. 
1,229,716, U.S. Pat. No. 3,147,318 and DE-AS No. 1,247,666. The quantity 
of comonomer used and the other measures should result in a gel content of 
the cross linked latex of from 40% to 100%, preferably from 60% to 99%, 
and to a swelling index of the gel component of from 5 to 90, preferably 
from 10 to 60. The gel content and swelling index are determined in 
toluene by the method described hereinafter. 
Sulphur is preferably used in quantities of 0.05 to 2.0% by weight, based 
on the monomers, in particular 0.1 to 0.7% by weight, and preferably in 
the form of an aqueous dispersion. 
The usual sulphur donors may be used in corresponding quantities instead of 
sulphur. 
Examples of suitable peroxo activators include persulphates, perborates, 
percarbonates, perphosphates and H.sub.2 O.sub.2 and in particular the 
water soluble salts of peroxodisulphuric acid, which are preferred. The 
activators are preferably put into the process in a molar quantity 
corresponding to 0.03 to 3.0% by weight, in particular 0.1 to 1.0% by 
weight of potassium peroxodisulphate, based on the quantity of monomers. 
5 to 30% of the total quantity of peroxo activator is preferably added at 
the onset of polymarisation and the remaining 70 to 95% during 
polymerisation, either portion-wise or continuously. 
Sodium-anthraquinone-2-sulphonate is preferably used in addition in a 
quantity of 0.005 to 0.1% by weight, based on the monomers. It is added as 
a solution together with the peroxo activator or preferably introduced 
quantitatively into the polymerisation mixture prior to activation. 
Polymerisation is carried out at temperatures from -10.degree. C. to 
70.degree. C., preferably at 0.degree. to 50.degree. C. 
Xanthogen disulphides and preferably mercaptans are used as regulators. 
Suitable agents for stopping polymerisation are, for example, pyrocatechol 
and, preferably, diethyl hydroxylamine, which is used in a quantity of 
0.05 to 0.15% by weight, based on the monomers, preferably in the form of 
an aqueous solution. 
Conventional stabilisers such as sterically hindered phenol derivatives, 
amines, phosphites, xanthogen disulphides or thiuramic disulphides are 
used to improve the storage stability of the polymers. Tetraalkyl 
thiuramic disulphides are preferred, optionally in combination with 
compounds from the other classes of substances. 
These compounds are added to the latex as aqueous dispersions, organic 
solutions or aqueous emulsions of an organic solution before or after 
removal of unreacted monomers. 
Up to 6% by weight of tetraethyl thiuramic disulphide (TETD) or a 
corresponding molar quantity of another compound or compound mixture may 
be used. The mixing of the sulfur-containing gel polymer and the 
uncrosslinked sol polymer is preferably performed in the latex state 
before the isolation of the dry polymers.

EXAMPLES 
(a) Preparation of the gel components 
The gel components of series (1) to (6) were prepared according to the 
following basic formulation (batch experiments, quantities given in parts 
by weight): 
______________________________________ 
Chloroprene and comonomer 100 
Salt free water (total quantity) 
128 to 133 
Sodium salt of disproportionated 
3.5 
abietic acid 
Sodium salt of the condensation 
0.7 
product of naphthalene sulphonic 
acid and formaldehyde 
KOH 0.5 
K.sub.2 S.sub.2 O.sub.8 0.07 to 0.50 
Sodium salt of anthraquinone 
0.03 
sulphonic acid 
Sulphur 0.5 
Sodium dibutyl dithiocarbamate (DBDTC) 
0.13 to 2.0 
TETD 1.0 to 4.0 
______________________________________ 
In the experiments of series (3) to (6), ethylene glycol dimethacrylate 
(EGDM) was used in addition as cross linking agent. (Total monomer 
quantity again 100 parts by weight). 
The batch experiments were carried out in a reactor with stirrer. The 
aqueous phase consisting of 120 parts of water, disproportionated abietic 
acid, sodium salt of naphthalene sulphonic acid containing methylene 
bridges and KOH was introduced into this vessel, flushed with nitrogen and 
heated to the temperature indicated in the tables. The monomer or monomers 
flushed with nitrogen were then added. In the examples containing cross 
linking agent, the latter was dissolved in the monomer. After adjustment 
to the temperature indicated in the Tables, the sulphur was added as a 50% 
by weight aqueous dispersion and DBDTC as a 30% by weight aqueous 
solution. The sulphur dispersion had the following composition: 
50% by weight sulphur 
49% by weight water 
0.82% by weight dispersing agent (based on cellulose ether) 
0.08% by weight zinc oxide 
0.10% by weight magnesium oxide. 
The reaction was then initiated with a small quantity of a dilute aqueous 
K.sub.2 S.sub.2 O.sub.8 solution which had been flushed with nitrogen, and 
polymerisation was sustained during the experiment by further addition of 
this aqueous, nitrogen-flushed persulphate solution. The quantity of water 
given in the basic formulation is made up of the original quantity of 
water put into the process and the water added with the aqueous solutions 
and dispersions of the reactants. The quantities of persulphate required 
for obtaining the given conversion rates are shown in the Tables. 
The conversion rate is checked gravimetrically. In the batch experiments, 
the reaction was stopped with 0.03 parts by weight, based on the latex, of 
an aqueous, 2.5% by weight solution of diethyl hydroxylamine, and 
tetraethyl thiuramic disulphide (TETD) was added to the latex in the 
quantity indicated in the Tables. TETD was used as a 25% by weight 
emulsion in toluene. 
The latex was degasified to a residual chloroprene content (based on the 
latex) of about 500 ppm. 
The continuous production of gel components was carried out in a cascade of 
5 vessels. The dwell time in each of the 5 vessels, which were equal in 
size, was 0.5 hours. The monomers, aqueous phase and activators were 
introduced into the first reactor in three separate streams. 
The individual phases had the following compositions (parts by weight): 
______________________________________ 
Monomer phase 
chloroprene 
2,3-dichlorobutadiene together 100 
EGDM 
phenothiazine 0.01 
Aqueous phase 
salt free water 102 
sodium salt of disproportionated 
3.5 
abietic acid 
KOH 0.42 
sodium salt of the condensation 
0.7 
product of naphthalene sulphonic 
acid and formaldehyde 
sodium salt of anthraquinone- 
0.06 
2-sulphonic acid 
sulphur 0.5 
DBDTC 0.13-1.0 
TETD 1.0 to 2.0 
Activator solution 
Potassium peroxodisulphate 
0.26 to 0.36 
added as a 1.2% 
by weight aqueous 
solution. 
______________________________________ 
The activator was fed separately into vessels 1 to 4. The distribution of 
the conversion rate over the individual vessels and the final degree of 
conversion could be adjusted by the quantity of persulphate added. 
Below are given two examples of adjustments to different final conversions: 
______________________________________ 
Experiment without cross linking agent (EGDM): 
K.sub.2 S.sub.2 O.sub.8 supply 
Total conversion 
Reactor (parts by weight) 
(%) 
______________________________________ 
1 0.08 54 
2 0.07 80 
3 0.06 92 
4 0.05 95 
5 -- 95 
______________________________________ 
Experiment with cross linking agent: (EGDM): 
K.sub.2 S.sub.2 O.sub.8 
Total conversion 
Reactor (parts by weight) 
(%) 
______________________________________ 
1 0.15 42 
2 0.09 69 
3 0.08 83 
4 0.04 90 
5 -- 90 
______________________________________ 
TETD was fed into the 5th vessel of the cascade as a 15% by weight solution 
in chloroprene. 
In a separate stirrer vessel, polymerisation was continuously stopped with 
0.1 parts by weight of diethyl hydroxylamine introduced as a 2.5% by 
weight aqueous solution. Degasification of the continuously produced 
latices was carried out as in the batch experiments. 
The gel components of comparison series (1) and (2) were prepared according 
to DE-PS No. 1,720,107, DE-OS No. 3,120,792 and DE-OS. No. 3,123,905. 
The gel component used in the comparison example in series (8) was prepared 
according to DE-OS No. 3,234,318, Example 5. 
(b) Preparation of the sol components 
The sol component of series (2) (experiments (a-d), (4), (5), (6) and (7) 
and of the comparison series (1) and (2) was prepared according to DE-OS 
No. 3,002,711, example 13. The sol component of series (2) (experiments 
(e-h) and series (8) (example 1) was prepared according to DE-OS No. 
2,306,610 (polymerisation example II). The sol component of the comparison 
example in series (8) was prepared according to DE-OS No. 3,234,318, 
example 2. 
(c) Preparation and working up of the sol-gel mixtures 
The degasified latex of the polychloroprene gel was mixed with the 
degasified latex of the polychloroprene sol in the given proportions (see 
tables). The latex mixture was adjusted to pH 6.5 with a 20% by weight 
acetic acid and the polymer was isolated by freezing coagulation and 
washed with water. The sheets obtained were dewatered to a residual 
moisture content of about 30% by weight by means of squeezing rollers and 
dried to a residual moisture content below 0.5% by weight in a circulating 
air drying cupboard at 70.degree. C. 
(d) Characterisation of the crude rubber 
The following determinations were carried out on the crude rubber: 
Gel content in toluene: 100 to 150 mg of the polymer were left to stand in 
20 cm of toluene for 12 to 16 hours and then shaken for 2 hours. The 
insoluble component was separated by centrifuging, dried and weighed and 
its quantity recorded as a percentage of the polymer weight. 
The swelling index (Q.sub.i) of the gel content was calculated from the 
quantity of toluene (m.sub.T) remaining in the gel (after centrifuging at 
500,000 m/sec) and the dry weight of the gel (m.sub.gel): 
EQU Q.sub.i =m.sub.T /m.sub.gel 
The Mooney viscosity (ML 1+4) was determined at 100.degree. C. according to 
DIN 53 523, part 1-3. 
The processing characteristics were tested on products obtained from the 
following mixtures: 
Mixture 1 
100.0 parts by weight of polymer 
60.0 parts by weight of carbon black (N 990) 
10.0 parts by weight of sodium-aluminium silicate 
5.0 parts by weight of aromatic mineral oil 
2.0 parts by weight of phenyl -.alpha.-naphthylamine 
1.0 part by weight of stearic acid 
4.0 parts by weight of magnesium oxide 
Mixture 2 
100.0 parts by weight of polymer 
50.0 parts by weight of carbon black (N 990) 
50.0 parts by weight of carbon black (N 539) 
30.0 parts by weight of aromatic mineral oil 
2.0 parts by weight of phenyl-.alpha.-naphthylamine 
1.0 part by weight of stearic acid 
1.0 part by weight of paraffinic anti-ozonant wax 
4.0 parts by weight of magnesium oxide. 
Mixture 3 
100.0 parts by weight of polymer 
25.0 parts by weight of carbon black (N 990) 
25.0 parts by weight of carbon black (N 539) 
15.0 parts by weight of aromatic mineral oil 
2.0 parts by weight of phenyl-.alpha.-naphthylamine 
1.0 part by weight of stearic acid 
1.0 part by weight of paraffinic anti-ozonant wax 
4.0 parts by weight of magnesium oxide. 
Mixture 4 
100.0 parts by weight of polymer 
10.0 parts by weight of chalk 
1.0 part by weight of paraffinic mineral oil 
2.0 parts by weight of a mixture of alkylated phenols 
0.5 parts by weight of stearic acid 
4.0 parts by weight of magnesium oxide. 
The processing qualities were tested by the following methods: 
Mixtures 1 to 3 
1.2 kg of the components of a mixture were mixed at 30.degree. C. in a 1 
liter kneader at 30 revs. per min. 200 g of the mixture were extruded 
through a 4.2 mm die of a Brabender laboratory extruder (10-D screw) at 
temperatures of 60 (cylinder) to 70.degree. C. (extrusion head) to form a 
strand of circular cross section on which the swelling after extrusion (in 
%) was subsequently determined. 
Mixture 4 
1.2 kg of the components of a mixture were mixed at 30.degree. C. in a 1 
liter kneader at 30 revs per min. 300 g of this test mixture were extruded 
as a band 8 mm in width and 2 mm in thickness by means of a Brabender 
laboratory extruder (10-D-screw) at temperatures of 70 (cylinder) to 
90.degree. C. (extrusion head) to form a Garvey profile according to 
ASTM-D 2230-78 and the swelling after extrusion (in %) was subsequently 
determined. 
Mixtures 1 to 4 
500 g of the test mixture were rotated as a sheet at 30.degree. C. on 
rollers (320.times.200 mm) rotating at 20 revs. per min. and separated by 
a gap of 0.9 mm. Two strips measuring 5.times.50 cm were cut out of the 
sheet and left on a small support covered with talcum. 
The length was measured after 24 hours and the mean value obtained from two 
samples recorded as the relaxation (in %). 
(e) Testing of vulcanization and of vulcanisate 
Vulcanisations were carried out on the basis of two mixtures 
Mixture 5 (iso-mixture 2475) 
100.0 parts by weight of polymer 
30.0 parts by weight of carbon black (N 762) 
0.5 parts by weight of stearic acid 
2.0 parts by weight of phenyl-.beta.-naphthylamine 
4.0 parts by weight of magnesium oxide 
5.0 parts by weight of active zinc oxide 
0.5 parts by weight of ethylene thiourea 
Mixture 6 (DIN 53670, part 5) 
100.0 parts by weight of polymer 
30.0 parts by weight of carbon black (N 762) 
0.5 parts by weight of stearic acid 
4.0 parts by weight of magnesium oxide 
5.0 parts by weight of active zinc oxide 
0.5 parts by weight of ethylene thiourea. 
The Mooney scorch (MS) was determined at a temperature of 120.degree. C. 
according to DIN 53 523 part 4. 
The tensile strength, elongation at break and modulus at 300% elongation 
were determined on the vulcanisate according to DIN 53 504 after a 
vulcanisation time of 30 minutes. 
The tear propagation resistance was determined according to DIN 53 504 on a 
standard ring R 2. For this test, 2.times.5 incisions 1 mm in depth placed 
side by side were made on the inside of the ring. The distance between the 
incisions was 2 mm. The two groups of five incisions were arranged 
opposite each other. 
The rings with incisions were placed on rollers having the dimensions for 
the standard ring R 2, see DIN 53 504, table 3, and the rings were 
subjected to tension in a tension testing machine at a feed rate of 700 
mm/min until breakage occurred. 
The tear propagation resistance W or structural strength is converted to a 
nominal thickness of d.sub.o =4 mm according to the following equation and 
the result given in N: 
##EQU1## 
wherein W [N]=tear propagation resistance to be found 
W.sub.gem [N]=tear propagation resistance measured 
d.sub.o [mm]=nominal thickness 
d [mm]=thickness measured. 
The mean value of the results obtained from 3 or 6 samples is calculated 
and the corresponding confidence range for 95% safety indicated according 
to DIN 53598. 
(f) Examples according to the invention and results 
Series (1) 
In this series, the preparation of sulphurmodified polychloroprene gel 
without cross linking agent is described. The gel content of the polymer 
and the swelling index of the gel content are determined by the conversion 
rate and the quantity of dibutyl dithiocarbamate. The process may be 
carried out continuously or batch-wise. 
Series (2) 
The experiments summarised in this series demonstrate that the 
polychloroprene mixtures prepared according to the invention reach a high 
level of quality in the combination of properties of their vulcanisates 
(high tensile strength, high modulus, high tear propagation resistance 
combined with high surface quality of the extrudates). 
__________________________________________________________________________ 
Series (1): Preparation of S-modified gels in the presence of dibutyl 
dithiocarbamate (DBDTC) 
without cross linking agent 
TETD 
subse- Gel 
contin- temperature 
conversion quently 
ML 1 + 4 
content 
Swelling 
Batch 
uous 
sulphur 
DBDTC 
(.degree.C.) 
(%) K.sub.2 S.sub.2 O.sub.8 
added 
(ME) (%) index 
__________________________________________________________________________ 
x -- 0.5 0.25 45 91 0.28 1.0 118 64 45 
x -- 0.5 0.25 45 97 0.32 1.0 80 69 40 
x -- 0.5 0.13 45 98 0.29 1.0 110 95 38 
-- x 0.5 0.13 45 95 0.36 1.0 115 90 36 
__________________________________________________________________________ 
__________________________________________________________________________ 
Series (2): Conditions of preparation of gels (I to II) prepared with 
dibutyl dithiocarbamate 
without cross linking agent and mixed with sol polymers (mixtures a to m) 
and 
tested for qualities for practical application 
Gel 
TETD con- 
monomer subse- 
conver- tent 
Swell- 
Experi- 
Discon- 
contin- chloro- 
dichloro- 
Temp. 
quently 
sion (% by 
ing 
ment 
tinuous 
uous 
sulphur 
DBDTC 
prene 
butadiene 
(.degree.C.) 
added 
(%) K.sub.2 S.sub.2 O.sub.8 
wt) index 
__________________________________________________________________________ 
I x -- 0.5 0.13 98.8 
1.2 45 3.0 93 0.49 95 25 
II x -- 0.5 0.13 98.8 
1.2 45 2.0 93 0.50 84 45 
__________________________________________________________________________ 
__________________________________________________________________________ 
Series (2): Data for practical application of the sol/gel mixtures 
prepared with gels I. II and III 
__________________________________________________________________________ 
elonga- 
M at 300% 
tear propaga- 
proportions Tensile 
tion at 
elonga- 
tion resis- 
Experi- 
gel 
sol in mixture 
ML 1 + 4 
Test MS.sub.5 
strength 
break 
tion tance 
ment 
type 
type sol:gel 
(ME) mixture 
(min) 
(mPa) 
(%) (mPa) (N) 
__________________________________________________________________________ 
a I mercap- 
100:0 50 5 10 18.4 410 13.1 161 
tan 
b I regulat- 
90:10 62 5 13 18.9 430 12.6 166 
ed 
c I regulat- 
80:20 78 5 13 19.4 440 12.4 200 
ed 
d I regulat- 
70:30 91 5 12 20.1 470 12.0 206 
ed 
e II xantho- 
100:0 43 5 -- 19.7 440 12.4 157 
gen 
f II disulph- 
90:10 53 5 -- 20.4 440 13.0 180 
ide 
g II regulat- 
80:20 63 5 -- 20.4 440 13.0 179 
h II ed 70:30 75 5 -- 19.7 440 12.9 165 
__________________________________________________________________________ 
swelling after 
relaxation 
extrusion 
surface 
Experiment 
test mixture 
(%) (%) quality 
__________________________________________________________________________ 
b 1 60 44 1 
c 1 60 37 2 
d 2 30 30 2 
f 3 69 49 2 
g 3 68 45 2 
h 3 71 42 3 
__________________________________________________________________________ 
Series (3) 
The preparation of sulphur-modified gels using DBDTC in the presence of 
EGDM is described in this series. The process of preparation may be 
carried out discontinuously or continuously. The gel content and swelling 
index can be adjusted to desired values. 
In the range selected, the polymerisation temperature has no substantial 
influence on the Mooney viscosity, gel content and swelling index of the 
sulphur modified gel. 
Series (4) 
In this series, the quantity of cross linking agent (EGDM) is varied. When 
the results obtained are compared with those of pure, sulphur modified 
gel, it is found that the Mooney viscosity, gel content and swelling index 
can be adjusted to desired values by means of the quantity of cross 
linking agent used. The Mooney viscosity and gel content increase with 
increasing quantity of cross linking agent while the swelling index 
decreases. 
When the sol/gel mixtures prepared from the gel polymer which has been 
prepared according to the invention are compared with sol/gel blends 
prepared according to the state of the art (conparison series 1), the 
mixtures prepared according to the invention are found to have higher 
tensile strengths which, in contrast to the comparison Series (1), do not 
decrease with increasing proportions of gel polymer. In addition, the 
vulcanisates obtained from mixtures prepared according to the invention 
have higher tear propagation resistances than the examples of the 
comparison series. 
Series (5) 
In this series the quantity of DBDTC is varied. The results obtained with 
the pure sulphur-modified gel polymer demonstrate that the Mooney 
viscosity, gel content and swelling index of the gel can be varied by 
means of the quantity of DBDTC used. As the quantity of DBDTC increases, 
the Mooney viscosity and the gel content of the gel polymer decrease while 
the swelling index of the gel increases. 
Sol/gel mixtures prepared from the gel polymer produced according to the 
invention give rise to vulcanisates which have substantially higher 
tensile strengths than those obtained in comparison series (2) and, in 
contrast to the values obtained in the comparison series, the tensile 
strengths do not decrease with increasing proportion of gel polymer in the 
polymer mixture. The tear propagation resistance values are also 
substantially higher than in the comparison series (2). 
Series (6) 
In this example, a gel is prepared at a higher temperature. The data of the 
pure gel polymer and of the sol/gel mixtures prepared from it correspond 
to the properties obtained in experiment II. 
Series (7) 
In this example, the gel is prepared continuously. The data of the pure gel 
polymer and of the sol/gel mixtures obtained from the polymer correspond 
to the properties of the discontinuously prepared gel polymers. 
The sol/gel mixtures prepared from the gel polymer produced according to 
the invention have high values for tensile strength and tear propagation 
resistance even when the gel polymer is prepared continuously. 
Series (8) 
In this series, the data of sol/gel polymer mixtures 
Series (8) prepared according to the invention are compared with those of a 
sol/gel polymer mixture in which both the sol component and the gel 
component contain elementary sulphur (according to DE-OS No. 3,234,318). 
The polymer mixtures prepared according to the invention combine high 
tensile strength with high modulus of the vulcanisates and good surface 
properties of the extrudates This combination of properties cannot be 
obtained with polymer mixtures according to DE-OS No. 3,234,318. 
__________________________________________________________________________ 
Series (3): Preparation of S-modified gels in the presence fo DBDTC and 
EGDM 
Gel 
TETD con- 
Temper- Conver- 
subse- tent 
Swell- 
Discon- 
contin- ature sion quently 
ML 1 + 4 
(% by 
ing 
tinuous 
uous 
sulphur 
DBDTC 
EGDM (.degree.C.) 
K.sub.2 S.sub.2 O.sub.8 
(%) added 
(ME) wt) index 
__________________________________________________________________________ 
x -- 0.5 1.0 5.0 45 0.16 82 2.0 118 84 14 
x -- 0.5 1.0 5.0 30 0.12 83 2.0 120 87 14 
x -- 0.5 1.0 5.0 30 0.07 78 2.0 118 86 15 
-- x 0.5 1.0 5.0 45 0.26 80 2.0 107 85 11 
-- x 0.5 1.0 2.0 30 0.36 91 2.0 118 82 12 
-- x 0.5 1.0 4.0 30 0.36 90 2.0 94 88 10 
__________________________________________________________________________ 
__________________________________________________________________________ 
Series (4): Conditions of preparation of gels (I to III) in which the 
quantity of cross 
linking agent was varied and the products obtained by mixing the gels 
with 
sol polymers (mixtures a to n) were tested for their properties for 
practical application. 
Gel 
con- 
TGETD tent 
tem- Conver- 
subse- in 
Swell- 
Experi- 
discon- 
Conti- perature sion quently 
ML 1 + 4 
uene 
ing 
ment 
tinuous 
uous 
sulphur 
DBDTC 
EGDM (.degree.C.) 
K.sub.2 S.sub.2 O.sub.8 
(%) added (ME) (%) index 
__________________________________________________________________________ 
I x -- 0.5 1.0 2.5 30 0.11 80 3.0 104 72 25 
II x -- 0.5 1.0 5.0 30 0.14 80 3.0 108 84 16 
III x -- 0.5 1.0 7.5 30 0.14 80 3.0 109 86 13 
__________________________________________________________________________ 
__________________________________________________________________________ 
Series (5): Conditions for the preparation of gels IV to VI in which the 
quantity of 
peptising agent was varied and the products of their mixtures with sol 
polymers (mixtures a to n) were tested for their properties for 
practical 
application. 
tem- TETD Gel 
pera- Conver- 
subse- con- 
Swell- 
Experi- 
discon- 
contin- ture sion quently 
ML 1 + 4 
tent 
ing 
ment 
tinuous 
uous 
sulphur 
DBDTC 
EGDM (.degree.C.) 
K.sub.2 S.sub.2 O.sub.8 
(%) added 
(ME) (%) 
index 
__________________________________________________________________________ 
IV x -- 0.5 0.5 5.0 30 0.12 80 1.0 132 86 12 
V x -- 0.5 1.5 5.0 30 0.24 80 3.0 110 84 13 
VI x -- 0.5 2.0 5.0 30 0.23 80 4.0 79 82 14 
__________________________________________________________________________ 
__________________________________________________________________________ 
Series (6): Conditions for the preparation of a gel VII which was 
prepared by the same 
method as gel II but at a higher temperature and then tested for 
practical 
application as mixtures with sol polymer (mixtures a to d) 
tem- TETD Gel 
pera- Conver- 
subse- con- 
swell- 
Experi- 
discon- 
contin- ture sion quently 
ML 1 + 4 
tent 
ing 
ment 
tinuous 
uous 
sulphur 
DBDTC 
EGDM (.degree.C.) 
K.sub.2 S.sub.2 O.sub.8 
(%) added 
(ME) (%) 
index 
__________________________________________________________________________ 
VII x -- 0.5 1.0 5.0 45 0.17 80 3.0 111 82 17 
__________________________________________________________________________ 
__________________________________________________________________________ 
Series (7): Conditions of preparation of a gel (VIII) prepared by a 
continuous process and tested 
for practical application as mixtures with sol polymer (mixtures a to c) 
TETD Gel con- 
Temper- conver- 
subse- tent 
Swell- 
Experi- 
discon- 
contin- ature sion quently 
ML 1 + 4 
toluene 
ing 
ment 
tinuous 
uous 
sulphur 
DBDTC 
EGDM (.degree.C.) 
K.sub.2 S.sub.2 O.sub.8 
(%) added 
(ME) (%) index 
__________________________________________________________________________ 
VIII 
-- x 0.5 1.0 3.0 30 0.36 90 2.0 85 89 13 
__________________________________________________________________________ 
__________________________________________________________________________ 
Series (4): Data of properties for practical application of the sol/gel 
mixtures containing gels I, II and III 
__________________________________________________________________________ 
M at 
300% 
tear propa- 
Proportions Test tensile 
Elongation 
elonga- 
gation re- 
Experi- 
gel of mixture 
ML 1 + 4 
Mix- 
MS.sub.5 
strength 
at break 
tion 
sistance 
ment 
type 
sol type 
sol:Gel 
(ME) ture 
(Min) 
(mPa) 
(%) (mPa) 
(N) 
__________________________________________________________________________ 
a I mercap- 
100:0 43 6 12 17.6 370 14.7 
175 
b I tan 85:15 50 6 14 17.4 380 14.0 
148 
c I regu- 
75:25 54 6 13 19.6 420 13.8 
213 
d I lated 
50:50 73 6 12 19.1 410 14.2 
152 
e I mercap- 
25:75 91 6 9 18.3 370 15.6 
145 
tan 
regu- 
lated 
f II mercap- 
85:15 50 6 12 18.5 400 13.7 
154 
g II tan 75:25 51 6 10 18.8 420 13.2 
180 
h II regu- 
50:50 66 6 9 18.5 420 14.2 
169 
i II lated 
25:75 91 6 8 16.7 360 14.7 
142 
k III 
mercap- 
85:15 48 6 -- 16.2 360 14.0 
148 
l III 
tan 75:25 52 6 14 18.0 400 13.4 
171 
m III 
regu- 
50:50 59 6 -- 15.6 360 13.9 
157 
n III 
lated 
25:75 75 6 -- 13.7 300 -- 123 
__________________________________________________________________________ 
relaxation 
swelling after extrusion 
Experiment 
test mixture 
(%) (%) 
__________________________________________________________________________ 
b 4 80 41 
c 4 80 39 
d 4 78 38 
e 4 75 34 
f 4 78 44 
g 4 78 42 
h 4 72 34 
i 4 58 25 
k 4 79 40 
l 4 77 42 
m 4 68 37 
n 4 52 21 
__________________________________________________________________________ 
__________________________________________________________________________ 
Series (5): Data for practical application of the sol/gel mixtures in 
which gels IV, V and VI were used 
__________________________________________________________________________ 
M at 
tear 
300% 
propaga- 
Proportions test Tensile 
Elongation 
elonga- 
tion 
Experi- 
Gel of mixture 
ML 1 + 4 
mix- 
MS.sub.5 
strength 
at break 
tion 
resistance 
ment 
type 
sol type 
sol:gel 
(ME) ture 
(Min) 
(mPa) 
(%) (mPa) 
(N) 
__________________________________________________________________________ 
a IV mercap- 
100:0 42 6 12 17.3 370 14.4 
169 
b IV tan 85:15 52 6 12 18.0 390 14.0 
186 
c IV regulat- 
75:25 56 6 10 18.4 380 14.8 
174 
d IV ed 50:50 72 6 7 18.4 360 16.6 
184 
e IV mercap- 
25:75 104 6 6 17.1 330 -- 147 
tan 
regulat- 
ed 
f V mercap- 
85:15 47 6 13 18.9 390 13.8 
172 
g V tan 75:25 51 6 14 19.0 410 13.9 
192 
h V regulat- 
50:50 63 6 14 17.2 400 13.4 
169 
i V ed 25:75 79 6 11 17.4 370 14.9 
172 
k VI mercap- 
85:15 48 6 15 18.3 390 14.0 
169 
l VI tan 75:25 51 6 12 18.8 420 13.2 
204 
m VI regulat- 
50:50 58 6 12 17.4 420 12.6 
180 
n VI ed 25:75 71 6 12 15.5 370 13.7 
137 
__________________________________________________________________________ 
relaxation 
swelling after extrusion 
Experiment 
Test mixture 
(%) (%) 
__________________________________________________________________________ 
b 4 79 41 
c 4 78 38 
d 4 72 33 
e 4 62 22 
f 4 81 44 
g 4 80 42 
h 4 72 34 
i 4 66 28 
k 4 80 46 
l 4 77 42 
m 4 69 39 
n 4 53 25 
__________________________________________________________________________ 
__________________________________________________________________________ 
Series (6): Data for practical application of the sol/gel mixtures in 
which gel VII was used 
__________________________________________________________________________ 
M at 
tear 
elonga- 
300% 
propaga- 
proportions tensile 
tion at 
elonga- 
tion 
Experi- 
gel of mixture 
ML 1 + 4 
test MS.sub.5 
strength 
break 
tion 
resistance 
ment 
type 
sol type 
sol:gel 
(ME) mixture 
(min) 
(mPa) 
(%) (mPa) 
(N) 
__________________________________________________________________________ 
a VII 
mercap- 
85:15 49 6 11 18.0 390 13.8 
170 
b VII 
tan 75:25 54 6 11 17.0 390 13.7 
177 
c VII 
regulat- 
50:50 70 6 8 18.2 400 14.0 
163 
d VII 
ed 25:75 93 6 8 16.6 350 13.9 
144 
__________________________________________________________________________ 
relaxation 
Swelling after extrusion 
Experiment 
test mixture 
(%) (%) 
__________________________________________________________________________ 
a 4 80 45 
b 4 78 43 
c 4 70 36 
d 4 59 25 
__________________________________________________________________________ 
__________________________________________________________________________ 
Series (7): Data for practical application of the sol/gel mixtures in 
which gel VIII was used 
__________________________________________________________________________ 
M at 
elonga- 
300% 
tear propa- 
Proportions Test 
tensile 
tion at 
elonga- 
gation 
Gel of mixture 
ML 1 + 4 
mix- 
strength 
break 
tion 
resistance 
Experiment 
type 
sol type 
sol:gel 
(ME) ture 
(mPa) 
(%) (MPa) 
(N) 
__________________________________________________________________________ 
a VIII 
mercap- 
100:0 45 5 19.1 440 12.3 
160 
b VIII 
tan 75:25 57 5 20.2 480 11.5 
187 
c VIII 
regulat- 
50:50 67 5 17.6 420 12.6 
168 
ed 
__________________________________________________________________________ 
relaxation 
swelling after extrusion 
experiment 
test mixture 
(%) (%) 
__________________________________________________________________________ 
a 3 61 41 
b 3 50 26 
__________________________________________________________________________ 
__________________________________________________________________________ 
Comparison series (1): Conditions for preparation of n-DDM-regulated and 
EGDM-cross-linked 
gels (I to III) in which the quantity of cross linking agent was varied 
and which were mixed with 
sol polymers (mixtures a to h) and then tested for their properties for 
practical 
application 
gel content 
temperature 
conversion 
in toluene 
experiment 
discontinuous 
continuous 
EGDM n-DDM 
(.degree.C.) 
(%) (%) 
__________________________________________________________________________ 
I x -- 2.5 0.30 44 80 70 
II x -- 5.0 0.30 44 80 83 
III x -- 7.5 0.30 44 80 92 
__________________________________________________________________________ 
__________________________________________________________________________ 
Comparison series (2): Conditions for preparation of n-DDM-regulated and 
EDGM-cross-linked 
gels (IV to VI) in which the quantity of regulating agent was varied and 
which were mixed with sol 
polymers (mixtures a to k) and then tested for their properties for 
practical 
application 
gel content 
temperature 
conversion 
in toluene 
experiment 
discontinuous 
continuous 
EDGM n-DDM 
(.degree.C.) 
(%) (%) 
__________________________________________________________________________ 
IV x -- 5.0 0.20 44 80 89 
V x -- 5.0 0.35 44 80 81 
VI x -- 5.0 0.40 44 80 82 
__________________________________________________________________________ 
__________________________________________________________________________ 
Comparison series (1): Data for practical application of the sol/gel 
mixtures in which gels I, II and III 
were used. 
__________________________________________________________________________ 
elonga- 
M at 
tear propa- 
Proportions tensile 
tion at 
300% 
gation 
Experi- 
gel of mixture 
ML 1 + 4 
test MS.sub.5 
strength 
break 
elonga- 
resistance 
ment 
type 
sol type 
sol:gel 
(ME) mixture 
(min) 
(mPa) 
(%) tion 
(N) 
__________________________________________________________________________ 
a I mercap- 
100:0 39 6 11 16.2 340 -- 131 
b I tan 75:25 57 6 11 16.0 320 -- 151 
c I regulat- 
50:50 78 6 8 14.5 270 -- 137 
d I ed 25:75 95 6 6 13.7 240 -- 119 
e II mercap- 
75:25 52 6 11 14.9 310 -- 132 
f II tan 50:50 65 6 8 13.0 270 -- 128 
g II regulat- 
25:75 85 6 4 14.5 250 -- 121 
ed 
h III 
Mercap- 
75:25 51 6 12 16.0 330 -- 115 
i III 
tan 50:50 68 6 8 10.2 230 -- 112 
k III 
regulat- 
25:75 87 6 7 10.4 210 -- 95 
ed 
__________________________________________________________________________ 
relaxation 
swelling after extrusion 
experiment 
test mixture 
(%) (%) 
__________________________________________________________________________ 
b 4 &gt;80 39 
c 4 80 35 
d 4 76 33 
e 4 80 46 
f 4 70 35 
g 4 66 24 
h 4 78 47 
i 4 66 32 
k 4 60 22 
__________________________________________________________________________ 
__________________________________________________________________________ 
Comparison series (2): Data for practical application of the sol/gel 
mixtures in which gels IV, V and VI 
were used 
__________________________________________________________________________ 
M at 
elonga- 
300% 
tear propa- 
proportions tensile 
tion at 
elonga- 
gation 
experi- 
gel of mixture 
ML 1 + 4 
test MS.sub.5 
strength 
break 
tion 
resistance 
ment 
type 
sol type 
sol:gel 
(ME) mixture 
(min) 
(mPa) 
(%) (mPa) 
(N) 
__________________________________________________________________________ 
a IV mercap- 
100:0 39 6 11 16.2 340 -- 131 
b IV tan 75:25 57 6 12 15.6 320 -- 132 
c IV regulat- 
50:50 82 6 4 14.2 270 -- 131 
d IV ed 25:75 121 6 3 12.0 180 -- 137 
e V mercap- 
75:25 55 6 11 15.1 300 -- 139 
f V tan 50:50 68 6 8 15.7 300 -- 126 
g V regulated 
25:75 94 6 4 13.7 230 -- 114 
h VI mercap- 
75:25 51 6 11 16.3 330 -- 144 
i VI tan 50:50 63 6 9 14.5 290 -- 119 
k VI regulated 
25:75 79 6 7 11.8 240 -- 116 
__________________________________________________________________________ 
relaxation 
swelling after extrusion 
experiment 
test mixture 
(%) (%) 
__________________________________________________________________________ 
b 4 80 41 
c 4 72 27 
d 4 66 17 
e 4 &gt;80 43 
f 4 74 37 
g 4 67 25 
h 4 &gt;80 45 
i 4 73 38 
k 4 65 29 
__________________________________________________________________________ 
__________________________________________________________________________ 
Series (8): Comparison of the sol/gel mixtures according to the invention 
with those from DE-OS 3,234,318 
(comparison example) 
Conditions for preparation of the gel and sol components 
Gel component sol component TETD of the sol/ 
Example 
sulphur 
DBDTC 
EGDM conversion 
TETD 
sulphur 
TETD 
conversion 
gel mixture 
__________________________________________________________________________ 
1 0.5 0.13 
-- 93 2.0 -- -- 65 0.2 
corresponds to Experiment II in 
xanthogen disulphide- 
0.4 
Series 2) regulated 0.6 
2 0.5 1.0 5.0 80 3.0 -- -- 65 0.45 
corresponds to experiment II in 
mercaptan-regulated 
0.75 
Series 4) 1.5 
comparison 
0.8 0.9 4.0 78 0.7 0.6 0.65 
65 2.2 
example 2.5 
__________________________________________________________________________ 
______________________________________ 
Series (8): Comparison of the sol/gel mixtures according to the 
invention with those of DE-OS 3,234,318 
(comparison example) 
Data for practical application 
Proportions tensile M at 300% 
surface quality.sup.(1) 
of mixture 
test strength elongation 
of the extrudates 
sol:gel mixture (mPa) (mPa) (test mixture 4) 
______________________________________ 
90:10 5 20.4 13.0 2 
80:20 5 20.4 13.0 2 
70:30 5 19.7 12.9 1 
85:15 6 18.5 13.7 3 
75:25 6 18.8 13.2 2 
50:50 6 18.5 14.2 1 
80:20 5* 19.5 10.5 5 
50:50 5* 18.5 11.5 4 
______________________________________ 
.sup.(1) 1 = very good surface quality 
5 = poor surface quality 
The assessment includes roughness, presence of cracks and dimensional 
stability of the extrudates 
*without ethylene thiourea.