Патент USA US2374098

v’ A". 17’
‘UNITED ‘STATES ~4 PATENT 0mm
2,374,091;
PRESERVATION 0F RUBBER
No Drawing. Application January 14, 1943,
'
Serial No. 472,399
18 Claims. (Cl. 260-800)
The present invention relates to a method of '
retarding or preventing the deterioration of a
isopropyl ketone, methyl isobutyl ketone, benzoyl
acetone, hydracetyl acetone, monochloracetone.
rubber due to ‘aging or exposure to the atmos
phere and to the rubber compositions so ob
tained. It has long been known that such de
terioration can be greatly retarded by treating
the rubber before or after vulcanization with cer
dichlor acetone, ' acetonyl acetone, ethylidene
acetone, allyl acetone, hydroxy acetone, cyclo
hexanone, methyl cyclohexanone and equivalents
and analogues thereof.
oxidants. One object of this invention issto pro
vide a superior class oi antioxidants for a rub-_
ber.
'
There ‘is ‘considerable variation in the effec
tain substances known as age-resisters or anti
tiveness of the new condensation products de
pending upon the position and number of the
amino groups and the ketone with which they
are condensed. It is preferred to employ the con
10.
. The antioxidants or age-resisters oi‘ the pres
densation products of aliphatic ketones and the
amino diarylene compounds of the structure
ent invention are obtained by condensing a
ketone with an amino substituted diarylene com
pound. Inaccordance with this invention it has
been discovered that the condensation products
of~ketones~and~amizies containing the nucleus
R\_-/R
,
x
in which one of the ‘ortho arylene groups repre
sented by R'contains a single primary amino sub
20 stituent and where X has the same-signi?cance
‘which nucleus contains at least one primary
,
amino substituent and where the R’s are ortho
arylene groups and X is a nonmetallic divalent
bridge forming group, comprise an effective‘ group
of antioxidants. Examples oi amines which may
be condensed with ketones to form the new anti
oxidants comprise the amino diarylene furans as
for example amino dibenzo furan, amino ca di
as before.
Best results are obtained where a
single primary amino group
3 position in the nucleus
25V
5
naphtho furan, amino pp dinaphtho furan and
is linked in the 2 or ‘
4
X
4 amino iso dinaphtho furan, the amino diarylene 80
thiophens as for example amino dinaphtho thio
phen and amino dibenzo thiophen, the amino
?uorenes as for example amino chryso ?uorene,
amino iso naphtha ?uorene, amino picene ?uo
rene and its isomers amino an: dinaphtho ?uorene 85
and amino pp dlnaphtho ?uorene, the amino di
arylene pyrroles as for example amino dibe'nzo ‘
where x is methylene, oxygen or sulfur. The
acetone condensation products ‘of these amines .
are equal to the most effective antioxidants
known for a rubber.
‘
.
The age resisting characteristics of a vulcan
ized rubber product can be readily ascertained by
subjecting samples oi the
_
vulcanized product in a
pyrrole (amino carbazole), the amino naphtho
bomb to the action oi air or oxygen under ele
benzO pyrroles, the amino dinaphtho pyrroles and
the amino phenanthro benzo pyrroles. Amines 40 vated temperature and pressure. The aged rubber
samples are then examined and tested and the
of this class may be prepared by nitrating, pref
test data compared with the results obtained on
erably mono nitrating, the diarylene compound
testing the unaged rubber samples. The ‘de
and reducing the nitro group to an amino group.
In the case of the pyrrole derivatives the N ni
terioration in properties effected as a result of
ketone, dimethyl ketone, di n propyl ketone, di
centage of their original tensile strength.
,
As illustrative of the action of the new com
the oxidation is indicative of the result that would
troso. compound is ?rst prepared and this nitrated' 45 normally
be expected of that particular stock
followed by removal of the nitroso group in known
during actual service. Such a test produces an
manner and reduction of the nitro group to an
e?ect on a vulcanized rubber stock comparable
amino group. All of these reactions are well
with that resulting from several years of natural
known and understood.
aging of the rubber depending upon the conditions
Examples of suitable ketones with which the
of the test. When subjected to this test the pre
amines may be condensed to form the new age
ferred class of compounds show a powerful pre
resisters comprise acetone, diacetone alcohol,
servative eifect and rubber stocks containing the
mesityl oxide, phorone, isophorone, methyl ethyl
new compounds retain, after aging, a high per
ketone, acetophenone, benzophenone, diethyl
-
2,874,098
2
pounds but without limiting the invention, rub
ber stocks were compounded comprising ,
Stock
A
B
0
are only illustrative of the invention and other
Parts by Parts by Parts by
weight
weiaht
weight
Smoked sheets rubber ............ ..
100 ,
Benzoyl tbio benzotbiazole
Diphenyi guanidine _____ _Acetone-2 amino ?uorene._-..
Acetone-2 amino dibenzo furan
100
100
6
3
5
3
3
2
3
2
5
3
3
2
0. 8
0.8
0. 8
50
50
50
0. 2
0. 2
0. 2
1. 0 __________________ _.
........ --
1.0
Commercial antioxidant .............................. __
?exing agent, this shows that the new class of
materials combine valuable flex resisting prop
erties with their age resisting characteristics and
both to a degree found only in the most effective
materials known.
As mentioned above, the foregoing examples
________ _.
condensation products of ketones and amino
'diarylene compounds may be used. Mention may
be made of the condensation product of acetone
and 9 amino ?uorene and the condensation prod
uct of acetone and 2,’? diamino fluoren , however,
the age resisting properties of these products were
inferior to those of products obtained from mono
amines having the amino group linked to one
of the arylene radicles. Other examples com
1. 0
prise the condensation product of acetone and
the following amines: 3 amino ?uorene, 3 amino
The condensation product of‘ acetone and 2
dibenzo furan, 3 amino dibenzo tbiophen, 2 amino
amino fiuorene in the A stock was pre'pared by 20 carbazole, 3 amino carbazole, 1,2 diamino fluo
passing acetone vapor into the amine at 130° C.
rene, 1 amino dibenzo furan, 4 amino dibenzo fu
in the presence of a little iodine as catalyst. The
ran, 2,7 diamino dibenzo furan, 1,8 diamino di
product after recrystallizing from alcohol melted
benzo furan, 2,7 diamino dibenzo thiophen, 4
at 158-162° C. The condensation product of ace
amino dibenzo thiophen, 1 amino carbazole, 3,6
tone and 2-amino dibenzo furan contained in the 25 diamino carbazole, 2,7 diamino carbazole and 9
B stock was prepared in similar manner. Ace
amino carbazole.
tone vapor was passed into the amine at 110
Furthermore, the method of condensing the
115° C. in the presence of a. little iodine for about
ketone with the amine may vary widely from the
48 hours. The soft resin obtained was heated
procedure outlined above. While it has been
under 3 mm, pressure to remove any unreacted
found that the lower boiling ketones like methyl
30
material but the distillation was stopped when
ethyl ketone and acetone react most e?iciently
the product began to distill over and the residue
by passing the vapor of the ketone into the hot
comprising the composite reaction product was
amine in the presence of a condensation cata
Y incorporated into the rubber stock. The anti
lyst, the ketone may be re?uxed or fused with
oxidant in the 0 stock is a powerful commercial 35 the amine ‘or heated under a presure'grcater
antioxidant and anti-?exing agent of recognized
than atmospheric in an autoclave. Suitable con
importance prepared by condensing acetone and
para amino diphenyl.
densing agents include, in addition to iodine, sul
furic acid, benzene sulfonic acid, p-toluene sul
'The rubber stocks so compounded were vul
fonic acid, bromine and the like. The condensa- ‘
canized in the usual manner by heating in a 40 tions take place with elimination of water and
press for diiferent periods of time and samples
where the ketone is passed into the reaction mix
of the vulcanized products were arti?cially aged
ture in the form of vapor, the portion which
by heating at 158° F. in, a bomb for 120 hours
escapes unreacted carries with it the water lib- under 300 pounds oxygen pressure per square
erated in the reaction. The vapor after drying
inch. The percentage of the original tensile
can then be recirculated through the system.
strength retained after aging is set forth in the
The products produced are believed to be
table below.
Table
Cure (time
in mins.)
Tensile
retained,
quinoline bodies. For example the principal con
stituent of the condensation product of acetone
and 2 amino ?uorene is believed to possess the
50 structure
CH3
per cent ‘
C
a
N/ \ CH:
H
but the invention is not limited to any theory of
structure and it is quite possible, especially
where the amino group is not in the 2 or 3 posi
The foregoing data show that the age resisting
properties of the preferred class of materials are
fully equivalent to those of the established com
60 tion, that other types of compounds are formed.
Furthermore, it should be understood that it
is unnecessary to isolate pure constituents from
the condensation products since the composite
mercial antioxidant.
The ?ex cracking resistance of'the vulcanized 65 reaction products are eminently satisfactory.
Obviously, practice of this invention is not lim
rubber products was determined on a ?exing
ited to the speci?c compositions given above, such
machine as set forth by L. V. Cooper, Analytical
compositions being merely illustrative of the
Edition of Industrial and Engineering Chemistry,
manner of employing the antioxidants or age
vol. 2, No. 4, 1930, pages 391-394. All three stocks
underwent approximately the same number of 70 resisters of this invention. The antioxidants or
age-resistors may be employed in conjunction
fiexings before failure. Likewise, after aging
seven days in an oven at 70° C., while the total
number of ?exings before failure was smaller,
all three stocks were approximately equivalent.
with other vulcanizing agents than those specifi
cally disclosed, for this invention is applicable
generally to pure rubber or rubber compositions
of the most varied nature. Furthermore, the
Since the control stock C contained a well known 75
2mm
preferred class of materials may be employed in‘ .
conjunction with other accelerators than those
speci?cally shown with
tion
product ofacetone and a primary ‘amine
having the structure
varying di?erences in .
tensile and modulus properties but still exhibiting \
the desirable properties of the‘ class.
It is to be understood that the term “treatingf’ :
as employed in the appended claims is used in a
i
‘
x
v ‘.
generic sense to include either the incorporating
of. the preferred class of materials into the rubber
by milling or similar process or-their addition to
the rubber latex before its ‘coagulation, or the
group' completing a ?ve membered ring said
bridging group comprising an ‘element which
application thereof to the surface of amass oi’ '
of two being satis?ed by hydrogen.o
where X is a nonmetallic divalent bridge forming
forms a heat ‘stable hydride, any valences in excess
crude or vulcanized rubber." The term
5. vThe ‘method of preserving. a rubber ‘which
her” is employed in‘ the claims to de?ne a“asulfur
vulcanizable plastic material which possesses
comprises treating a-rubber with the condensa
tion product of acetone and a primary amine hav
high extensibility under load coupled with the
property of forcibly retracting to approximately
itsoriginal size and shape after the load is-re
ing the structure
g
. ‘
Y
4
moved. Examples of such products are India
copolymers of butadiene and styrene and buts
vulcanizable
I
-—NHi
2
x/
diene and acrylic nitrile and other natural or
prepared
' y.
v
x
rubber, reclaimed rubber, balata, gutta percha. 20_
synthetically
v
products ' ‘
where the amino group is in the 2 or 3 position
which deteriorate upon aging or exposur‘e'to the
atmosphere by absorption of oxygen, whether or 25, and X is an element of group VI of the periodic
system oi’ atomic weight less than 50.
not admixed with ?llers, pigments or accelerating
6. The method of preserving India rubber
agents.
“
~
'
v
>
'
'
which comprises treating India rubber with the
condensation product of acetone and a‘primary
The present invention islimited solely by the
claims attached hereto as part of the present
speci?cation.
- a
30
What is claimed is?‘
amine having the structure
I
'
,
V
4
1. The method of preserving a rubber which
comprises treating a rubber with the condensa
tion product of an aliphatic ketone and a primary
amine having the structure
'
_
.35
where the- amino group
isinthe2or3position '
and X'is of methylene
7. The method of preserving a rubber which
where the R's are aiylene groups at least one of
which bears a primary amino group and X is a
comprises treating a rubber with thecondensa
nonmetallic divalent bridge forming group com 40 tion
product of acetone and 2 amino ?uorene.
pleting a ?ve membered ring said bridging group
8. The method‘ of preserving a rubber which
comprising an element which forms a heat stable
comprises treating a rubber with theconden'sa-v
hydride, any valences in excess of two being
tion product of acetone and 2 amino dibenzo
satis?ed by hydrogen.
7
.
475
2. The method of preserving a rubber which
9. The ‘method of ‘preserving a rubber which
comprises treating a rubber with the condensa- ’ comprises treating a rubber with the condensa
tion product of an aliphatic ketone and a primary
tion product of acetone and 3 amino dibenzo
furan.
amine having the structure
pyrrole.
60
‘
'
'
‘
i
-
'
10. The vulcanized rubber product obtained by
treating a rubber with the condensation prod
uct of an aliphatic ketone and a primary amine
where the R’s are phenylene groups at least one
I having the structure
of which bears a primary amino substituent and
X is a nonmetallic divalent bridge forming group 65
completing a ?ve membered ring said bridging
group comprising an element which forms a heat
where the Rs are aryiene groups at least one of
stable hydride, any valences in excess of two
which bears a primary amino group and X is a
being satis?ed by hydrogen.
.
nonmetallic divalent bridge forming group com
3. The method‘ of preserving a rubber which
comprises treating a rubber with the condensation 60 pleting a ?ve membered ring said bridging group
comprising an element which forms a heat stable
product of ‘an aliphatic ketone and a primary
hydride, any valences in excess of two being satis
amine having the structure
?ed by hydrogen.
>
11. The vulcanized rubber product obtained by ‘
65 treating a rubber with the condensation product
of an aliphatic-ketone and a primary amine hav
ing the structure
I
'
.
where X is a nonmetallic divalent bridge forming
X/
'
'
. R\_IR
group completing a ?ve membered ring said
bridging group comprising an element which 70
where the R's are phenylene groups at least one
forms a heat stable hydride, any valences in
of which bears a primary amino substituent and
excess of two being satis?ed by hydrogen.
‘X is a. nonmetallic divalent bridge forming group
4. The method of preserving a rubber which
completing a ?ve membered ring said bridging
comprises treating a rubber with the condensa
78 group comprising an element which forms a heat
2,374,098
' of acetone and a primary amine
stable
4. hydride.
~ any gvalenceain excess of two being
satisfied; by hydrogen.
12. The vulcanized rubberproduct obtained by
having- the struc
‘ ture
treating. a rubber with the condensation product
or an aliphatic ketone and a primary amine hav- 7
ing the structure ‘
I where the amino group is in the 2 or- 3' position
_
10
and X is an element of group VI of the periodic
system of atomic weight less than 50.
15. ' The vulcanized rubber product obtainedby
where X is a nonmetallic divalent bridge forming
‘ treating India rubber with the condensation prod
group completing» ‘a ?ve membered 1 ring said
> uct of acetone and a
bridging group comprising ‘an ‘element which
v forms a heat stable hydride, any valences in
primary amine having the
_ structure.
excess oftwo being satis?ed by hydrogen. 7
13. The vulcanized rubber product obtained by
. treating a rubber with the condensation product
of acetone and a primary amine having the struc
ture
'
'
L
'
V
_ where the amino group is in the 2 or 3 position '
and X is of methylene.
_
,
16. The vulcanized rubber product obtained by
treating a rubber with the condensation product
of acetone and 2 amino ?uorene.
where X is a nonmetailic divalent bridge forming _
group completing, a ?ve membered ring said
bridging group comprising an element which
‘forms a heat stable‘ hydride, any valences in
excess of‘ two being satis?ed by hydrogen. ‘
,
14. The‘vulcanized rubber product obtained by
treating a rubber with the condensation product
17. The vulcanized rubber product obtained by '
treating a rubbeer with the condensation product
of acetone and 2 amino dibenzo furan.
18. The vulcanized rubber product obtained by
treating a rubber with the condensation product
of acetone and 3 amino dibenzo pyrrole.
‘
'
JOSEPH R. INGRAM.