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Patented Nov. 19, 1946
2,411,413
UNITED STATES, __BATETNT OFFICE‘ ‘ '
RE'ISINOUS VULCANIZATION,ACCELERATORS
Elmer W. COOk‘LNBW York, N: Y., andilEdwi'n 0.1
Hook, Nor-walk, Conn., assignors to American‘
Cyanamid Company, New York, N. Y., a. cor
poration of ‘Maine
No Drawing. Application March. 23, .1944,
Serial No. 527,827‘
8 Claims. (Cl. 260-70)
1
2
This invention relates to accelerators for the,v
vulcanization of sulfur-vulcanizable-rubber and
rubber-like materials. More particularly, the
the accelerator used.
Mercaptobenzothiazole
Was used as the standard‘for comparison.
invention is concerned with vulcanization ac
‘
celerators comprising reaction products of zinc
Compounds-
chloride, formaldehyde, mercaptobenzothiazole
and a monoarylguanidine.
1“
The following examples, in which parts are
given by weight, are illustrative of suitable
methods of producing these vulcanization ac-i
Buna-S ________ __
celerators.
Product A
Carbon black.
_
Goal tar soften
Zinc oxide____
Sulfur ________________ __
_ ‘
_
_
Mercaptobenzothiazole __________________ __
Product A
,
Similarly, other accelerators may be prepared
by varying the proportions. Typical compounds
are those prepared by reacting mixtures contain
ing the reactants in the following molar propor
and 1:1:8t8.
‘
Product B
m
50
50 ‘
‘
5 a
5 i
2 " 1
1. 5
‘
,5
5
2
______________ _ _
;
> 100i
‘ ‘ 50_
5
5 »
2"
1.1- 1
‘
_ ‘
1:1
100° mches
15
25
tions, phenylguanidine carbonate: zinc chloride: 30
formaldehyde: mercaptobenzothiazole= 1 : 1 :2 :2,
3
Set-up tcsts~Williama-3“minr “Y” at
phenylguanidine carbonate was added and the
mixture heated to 105° C. for 15 minutes to drive
oif carbon dioxide and water. A- mixture of 50
parts (6 mols) of mercaptobenzothiazole and 9
parts (2 mols) of paraformaldehyde ( (CH20)3 ) 20
was added gradually to the melt which was main
tained at 130-135° C. for about 35 minutes. 0n
cooling, a hard, brittle, amber-colored resin was
obtained which was readily ground to a ?ne pow
der.
V
2 -
100
___
Product B
To a solution’ of 7 parts (1 mol) of zinc chlo
ride in 10 parts water, 16.5 parts (1 mol) of mono
l
water __________ _.
Change, percent ____________ n‘. ...... __‘_-..
Shore hardness _
‘
I
. 15B
. 164
. 18-6
. 195
71717. 7 7-1718‘. 9
l
I
‘
‘
Cure at 141° 0.:
30 minutes ___________________________ _.
60 minutes ___________________________ __
90 minutes ........................... ._
52
58
59
49
57
59
44
52
55
Tensile tests
30’ cure at 141° 0.:
Modulus at 200%1 ___________________ __
380
Modulus at 300%l.__
Tensile ! _____________ __
Elongtat‘iiogkpereent
1..
60 I cure
a 1 1
.:
Modulus at 200%\ ___________________ __
261)
165
500)
250
l, 935
900
55
730
680
645
535
350
Modulus at 300%1___
_
1, 270
l, 065
735
Tensile 1 _____________ __
_
2, 665
2, 660
2, 125
Elongatioudaercent
1
90 I euro
at 141
.:
_
490
5
605
Modulus at 200% 1 ___________________ ._
760
665
520 ‘
Modulus at 300% 1 ___________________ -_
1, 510
2, 950
470
1, 290
2, 665
480
Tensile 1 _____________________________ __
Elongation, percent 1 ________________ __
1, 070
2, 215
490
Starting with a mixture of 7.5 parts hydroxy 35
phenylguanidine (2 mols), 3.4 parts zinc chlo
1 LbJsq. in
3 Elongation at break.
ride (1 mol), 415 parts paraformaldehyde (2
mols), and 25 parts mercaptobenzothiazole (6
In the set-up tests, the highest percentage
mols), the procedure described for Product A
change on heating for 2.5 hours in boiling water
was repeated to give a resinous material some 40 indicates the greatest set-up and tendency to
what similar to Product A.
scorch or precure. The products of the present
The utility of these materials as vulcanization
invention show more delayed accelerator action
accelerators is more particularly illustrated by
than mercaptobenzothiazole but, at full cure, give
the following tests utilizing a butadiene-styrene
harder cured stocks than the latter material, in
copolymer as indicative. The compositions were 45 dicating that our products are stronger acceler
compounded in the usual manner on rubber rolls.
ators.
Each of the compounds was made up from the
As will be seen from the above tests the com
same rubber stock with the only variable being
pounds of the present invention have strong ac
2,411,413
3
3. As a vulcanization accelerator the resinous
celerator action. These accelerators do not bring
product
obtained by fusing 2 mols of a para- "
about undue precure and give hard cured stocks.
formaldehyde and 6 mols of mercaptobenzothi
Similar results are obtained with natural rubber
azole with one mol of the reaction product of 1-2
and, the various synthetic rubber-like materials
which may be vulcanized in the presence of sul 5 mols of zinc chloride and one mol of a guanidine
having the formula
fur. The proportion of accelerator used may be
varied widely although, for most purposes, the
least amount of accelerator is utilized which will
in which R is an aryl radical.
give the desired results. Of course, mixtures of
4. A vulcanization accelerator according to
the rubber-like materials with each other or with
claim 3 in which the guanidine is monophenyl
natural rubber may be vulcanized with the ac
celerators of the present invention. The vul
‘guanidine.
V
5. A vulcanization accelerator according to
canized compositions using these accelerators
claim 3 in which the guanidine is mono-o-tolyl
give somewhat lower rates of cut-growth than
mercaptobenzothiazole and this property is very 1 vguanidine.
6. A vulcanization accelerator according to
valuable, especially in synthetic rubber composi
tions.
7
The present invention is not restricted to the
,claim 3 in which the guanidine is mono-p-tolyl
guanidine.
speci?c processes given for the production of the
'7. The method of producing a vulcanization
accelerators since the methods of manufacture 20 accelerator which'comprises fusing a dried re
may be varied considerably to obtain substan
action productof 1-2 mols of zinc-chloride and
tially the same results. In place of the mono
1 mol of ‘a guanidine having the formula
phenylguanidine speci?cally set forth, mono
orthoto1yl-, p-tolyl, xylyl. naphthyl, alkyl-oxy
phenyl guanidines and similar mono-arylguan
idines may be used.
We claim:
.1.'The method of preparing a condensation
product which comprises reacting 1 mol of zinc
chloride in aqueous solution with 1 mol of mono
phenylguanidine carbonate at a temperature of
approximately 105° C., eliminating water and
carbon dioxide therefrom and condensing the
reaction product with a mixture of 6 mols of
mercaptobenzothiazole and 2 mols of paraform 35
aldehyde at a temperature of 130-135° C.
in which R. is an aryl radical, with 2 mols of
para-formaldehyde and 2-8 mols of a mercapto
benzothiazole.
8. The method of producing a vulcanization
accelerator which comprises fusing a dried re
action product of 1-2 mols of zinc-chloride and
1 mol of a guanidine having the formula
'
‘2. Asa vulcanization accelerator, the resinous
in which R is an aryl radical, with 2 mols of ,
product obtained by fusing 2-8 mols of a para
paraformaldehyde and_6 mols of mercaptobenzo
formaldehyde and 2-8 mols of mercaptobenzo
thiazole.
thiazole with one mol of the reaction product of
1-2 mols of zinc chloride and one mol of a
guanidine having the formula
H NH
-
R—-N—C-—NH2
in which'R is an aryl radical.
-
.
ELMER W. COOK.
‘EDWIN O. HOOK.
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