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Патент USA US2412985

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‘2,412,985
Patented Dec. 24, 1946
4 UNITED ‘STATES‘PATENT OFFICE.
2,412,985‘
VULCANIZA'I'ION 0F RUBBER
William H. Hill, Mount LebanonQPaq assignor,
by mesne assignments, to Koppers Company,
Inc., a corporation of Delaware
No' Drawing. Application May 24, 1944,
'
Serial No. 537,179
19 Claims.
"
(Cl. 260-797)
1
The present invention relates to vulcanization
of rubber and to rubber compositions or such
compositions vulcanized in the presence of ac
celerators,v and of accelerators and activators
herein described.
In connection with the present invention it
has been found that compounds formed from a
thiocyanate and amidine bases having the char
acteristic guanyl grouping are highly desirable
2
The purity of ' the product in the above methods
is increased by recrystallization of the crudes
from a solvent.
Each of the above-mentioned amidine thio
cyanates is produced in an analogous manner.
In addition, the thiocyanate of guanyl urea (di
cyandiamidine) is produced by hydrolyzing di
cyandiamid in an aqueous solution of thiocyanic
acid or in a mixture of ammonium thiocyanate
agents in vulcanization accelerators and particu 10 and a strong mineral acid, or by double decompo
sition of barium thiocyanate (Ba (SCNM) with
dicyandiamidine sulfate.
.
c.
I
thiazole accelerators including mercapto-aryl
As
illustrations
of
this
invention,
the
following
thiazoles, benzothiazyl‘ thiobenzoate, dibenzo
compositions were prepared:
thiazyl disul?de and others. Though amidine
thiocyanates have in themselves accelerating
properties, it is noted that they are particularly
Compo. tion,
larly as activators for accelerators such as
parts by
weight
valuable for commercial purposes as activators
for accelerators in various rubber stocks.
Speci?c examples of compounds employed
A
herein for the purposes de?ned include diphenyl 20
guanidine thiocyanate, such alkaryl amidine
Rubberthiocyanates as diorthotolyl guanidine thiocy
Carbon black-.
100
100
.
anate and dixylylguanidine thiocyanate, and also ‘
Zinc mrirle
dinaphthylguanidine thiocyanate, guanyl urea
thiocyanate and the like. In addition to these, 25
other amidine thiocyanates are used including
biguanide thiocyanates such as tolyl biguanide
thiocyanate and the like, but the latter are found
Stearic acid ________________________________________ __
to be not as effective.
B
-
45
l0
‘
115
1
4
Pine tan--Sulfur
Ureka C--.
2.5
.6
3
3
.6
Activator“
I .4
.4
The activator referred to in the above table
Compounds of the type employed in the present 30 represents any of the amidine compounds herein
mentioned. They are incorporated into the rub
ber mixes in ?nely divided form, the particle
size preferably being such as to pass through a
200 mesh sieve. Substantial traces of these com
an aqueous solution of ammonium thiocyanate
and diphenyl-guanidine in stoichiometric pro 35 pounds are effective. Additions of between sub
stantially 0.1% and 1% of the rubber in the com
portions. Ammonia is generated and expelled
position are generally satisfactory, a preferred
or withdrawn under vacuum, and the desired
invention are readily prepared by any one of
several methods. For example, diphenyl guani
dine thiocyanate is prepared by heating together
compound is ultimately found partially in solu
proportion being about 0.4% in the presence of
tion from which it crystallizes on cooling. It
also settles in the system as a liquid bottom layer 40
thiazoles.
-
An amidine such as diphenyl guanidine or the
like, and ammonium thiocyanate may be added
which solidi?es on cooling.
'
to a rubber mix separately orpreferably in ad
Another method of preparing an amidine thio
mixture with each other and chemically uncom
cyanate, such as the thiocyanate of diphenyl
lbined. The processing of the rubber mix, ‘e. g.,
guanidine is to fuse diphenyl guam'dine with am
monium thiocyanate, preferably under vacuum 45 on the rolls, etc., will cause these compounds to
react in situ to form the amidine thiocyanate
to aid in the removal of ammonia. A further
which promotes vulcanization. Alternatively, the
and more desirable method is to introduce the
amidine and thiocyanate may be added as a pow
amidine, such as diphenyl guanidine, into a cold
aqueous solution of thiocyanic acid, or an organic
“Ureka C,’.’ referred to in the above table, rep
solvent solution of- thiocyanic acid (HSCN) , such 50
resents a speci?c example of a thiazole acceler
' as an other solution of thiocyanic acid, obtained
ator, namely, benzothiazolethiol benzoate.
in known manner respectively by distilling a thio
The compositions A and B were vulcanized in a
cyanate with an acid or extracting with the or
heated mold for varying times at temperatures
ganic solvent an acidi?ed aqueous thiocyanate
55 indicated in the table below. Cured rubber prod
dered
solution.
‘
'
7
~
‘
‘
a
melt.
>
-
:
'
.
.
2,412,986
3
4
ucts were obtained in each case having the prop
porating in the rubber compound a small amount
erties tabulated.
of an accelerator composition containing as an
Table I
I
V
.
..
Moduli of elasticity
Cure time,
Activator (with mix A)
lgtligil‘é‘gi?‘t 81°11’
mins.
(274° F.)
Tensile at Elongation
g
break,
lbs./in.z
at break,
per cent
300%. 500% 700%
50
.
Diphenylguanidinc thiocyanate _______________ -_
.
.
Diortholclylguamdme thiocyanate ------------ _-
_
490
990
850
520
1, 860
2, 770
763
‘560
2, 410‘
3, 390
757
260
790
3, 010
3, 870 ‘
750
260
270
110
750
.650
160
2, 840
2, 510
490
3, 540
3, 460
1, 080
737
747
830
523 tit
3%?
810 3, 050
i278
3, 800
3Z3
735
300
300
110
810
780
270
3, 680
3, 820
1, 460
733
740
830
140
2,150
830
l 280
Orthotolylbiguanide thiocyanate .............. __
220
190
240 V
'
,
1
,
3, 100
3, 050
700
3
320
1,050
160
430
'1, 430
2, 630
810
160
190
400
510
l, 500
1, 600
2, 790
2, 880
803
800
Table II
Moduli of
Activator (with mix B)
Cure time,
elllast/icitzy
its
5' m‘. a
ruins.
elonéaiwns
(274° F.)
Tensile at Elongation
break,
lbs./in.2
at break,
per cent
300% 500%
.Diplienylguanidine thiocyanate ....................... .-
Diorthotolylguanidine thiocyanate .................... ._ 60
.
D‘rthotolylbiguanide thiocyanate ..................... ..V. 60
2, 110
2, 700
607
617
g’ 528
2%
3' 010
3, 050
550
520
2,510
7 610
3, 090
620
3, 120
527
3, 090
1, 550
510
570
2. 510
607
3, 090
828
557
2, 980
530
Other accelerator compositions containing
activator the thiocyanate salt of an aryl guani
amidine thiocyanates may be employed that are
dine.
within the scope of the classes herein de?ned
3. The improvement in vulcanization of rub
and may be substituted for the speci?c com 50 ber containing accelerators, which comprises in
pounds used in the examples. Such compositions
corporating in the rubber compound a small
are useful in vulcanizing any of the rubbery ma
amount of the thiocyanate salt of diphenyl guani
terials that are vulcanizable, including natural
dine.
‘
rubbers such as caoutchouc, balata, and gutta
4. The improvement in vulcanization of rub
percha; synthetic rubbers such as the Buna or
ber containing accelerators, which comprises in
Butyl types; or natural or arti?cially prepared
corporating in the rubber compound a small
latex. These are all designated herein by the
amount of the thiocyanate salt of diorthotolyl
generic term “rubber.”
'
The thiocyanates referred to herein are the
thiocyanate salts.
‘It is understood that the invention herein-de
scribed is not limited solely to the speci?c em
bodiments set forth, and that it is obvious to
those skilled in the art that many modi?cations
such as the application of equivalents and vary
ing proportions'are within the spirit and scope
of the invention de?ned in the appended claims.
What is claimed is:
1. The improvement in vulcanization of rubber
containing ‘accelerators, which‘ comprises incor
poration in a rubber compound of a small amount
of an accelerator vcomposition containing as an
activator the thiocyanate salt‘ of'a guanidine.
'2.‘ The improvement in vulcanization of rubber
containing: accelerators, ‘which comprises ‘incor; 75
guanidine.
5. The improvement in vulcanization of rub
ber containing accelerators, which comprises in
corporating in the rubber compound a small
‘amount of the thiocyanate salt of orthotolylbi
guanide.
6. A process of preparing a vulcanized rubber
product which comprises mixing a vulcanizable
rubber composition with a thiazole accelerator
and an activator comprising the thiocyanate salt
of a guanidine. and vulcanizing the rubber.
'7. A process of preparing a vulcanized rubber
product which comprises mixing a vulcanizable
rubber composition with an accelerator compris
ing benzothiazolethiol benzoate and an activator
comprising the thiocyanate salt of a guanidine,
and vulcanizing the rubber.
_
,
8. A process of preparing a vulcanized/rubber
2,412,995
5
product which comprises mixing a vulcanizable
rubber composition with an accelerator compris
ing benzothiazolethiol benzoate and an activator
comprising the thiocyanate salt of diphenylguani
dine and vulcanizing the rubber.
9. A process of preparing a vulcanized rubber
6
13. A product comprising rubber vulcanized in
the presence of an accelerator activated by the
thiocynate salt of a guanidine.
14. A product comprising rubber vulcanized in
the presence of a thiazole accelerator and the
thiocyanate salt of an aryl substituted guani
dine.
product which comprises mixing a vulcanizable
15. A method comprising vulcanizing a rubber
rubber composition with an accelerator compris
in the presence of an accelerator containing as an
ing benzothiazolethiol benzoate and an activator
comprising the thiocyanate salt of diorthotolyl 10 activator the thiocyanate salt of a guanidine.
16. A method comprising vulcanizing a rubber
guanidine and vulcanizing the rubber.
in
the presence of a thiazole accelerator and the
10. A process of preparing a vulcanized rubber
thiocyanate salt of an aryl substituted guani
product which comprises mixing a vulcanizable
dine.
,
rubber composition with an accelerator compris
ing benzothiazolethiol benzoate and an activator
comprising the thiocyanate salt of orthotolylbi
guanide ‘and vulcanizing the rubber.
17. A method comprising vulcanizing a rubber
in‘ the presence of a thiazole accelerator and the
thiocyanate salt of diphenylguanidine.
18. A method comprising vulcanizing a rubber
11. A composition comprising rubber, a vul
in
the presence of a thiazole accelerator and the
canizing agent, and an accelerator containing as
an activator the thiocyanate salt of a guanidine. 20 thiocyanate salt of diorthotolylguanidine.
19. A method comprising vulcanizing a rubber
12. A composition comprising rubber, a vul
in
the presence of a thiazole accelerator and the
canizing agent, an activatable type of organic ac
thiocyanate salt of orthotolylbiguanide.
celerator, and the thiocyanate salt of an aryl sub
WILLIAM H. HILL.
stituted guanidine.
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