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Патент USA US3078257

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3,0?8247
Patented Feb. 19, l$$3
2
once of radical-forming catalysts, such as for example
3,078,247
per compounds (peroxides, hydroperoxides, per acids) at
STABLE AQUEGUS EMULSlONS 0F ELASTGMERI€
CHLGROPRENE COPOLYMERS CON'i‘AlNlNG
pH values from about 3 to 6.
ZENC OXHDE
with molecular oxygen or with persulphates are also suit
Gustav Sinn, Bergisch-Neulrirchen, and Rosahl Dietrich
and Heinz Esser, Koln-Starnmheim, Germany, assignors
to Farbenfahrihen Bayer Alrtiengesellschatt, Lever
lrusen, Germany, a corporation of Germany
No Drawing. Filed Dec. 15, 1959, Ser. No. 859,555
Claims priarity, application Germany Dec. 19, 1953
4 Claims. (Cl. 260-2?!”
Redox systems such as
for example combinations of formamidinesulphinic acid
able as catalysts.
In this way, copolymers of chloro
prene are obtained which can be satisfactorily cross
linked with the said oxides. It is especially to be empha
sised in this connection that the ?lms are already cross
10 linked in the manner of vulcanisation after being dried
at room temperature. This discovery is surprising, since
The present invention relates to aqueous emulsions of
elastomeric chloroprene copolymers which are suitable
for the production of shaped elements.
It is known that vulcanising agents, such as sulphur or
zinc oxide and vulcanisation accelerators must be added
to the aqueous emulsions of synthetic elastomers, for ex
ample aqueous emulsions of polymers of butadiene or its
copolymers with styrene or acrylonitrile for the purpose
of producing elastic ?lms. The ?lms produced from the
latices are usually subjected to a vulcanisation process
polymers which are composed only of chloroprene and
methacrylic acid as polymerisation components do not
produce a reproducible cross-linking with metal oxides.
Furthermore, polymerisation mixtures containing a
third copolymerisation component of the type described
have the advantage that the polymerisation proceeds sur~
prisingly uniformly and in a readily controllable manner,
whereas mixtures containing only chloroprene and meth
acrylic acid polymerise in an extremely violent manner
with strong heat of reaction, so that they are di?cult to
control. In addition, when chloroprene and methacrylic
acid are used alone, the major part of the methacrylic
acid is not incorporated into the copolymer, but polym
that the ?lms are given their optimum properties, such
as for example high tearing strength, good elasticity, low .25 erises independently with formation of polymethacrylic
which requires a relatively long time and relatively high
temperatures. It is only by this vulcanisation process
acid.
abrasion and good resistance to oils and other chemicals.
The zinc oxide or other oxides of polyvalent metals are
It is also known to cross-link synthetic elastorners contain
preferably introduced into the said copolymer emulsion
ing carboxyl groups with Zinc oxide or other oxides of
by the said emulsion being adjusted by means of ammonia
polyvalent metals by these components being mixed and
heated to temperatures higher than 50° C. According to 30 or other compounds with an alkali action to a pH value
of about 6 to 6.5 and by adding to the emulsion a non
the known processes, however, vulcanisates are obtained
ionic stabiliser, such as for example a polyalkylene oxide
which do not satisfy all requirements as regards their re
derivative, in quantities of 1 to 5% by weight, calcu
sistance to weather influences and ozone or their resist
lated on the copolymer. For facilitating the incorpora
ance to heat and chemicals.
tion of the metal oxides into the said emulsions, they are
The present invention is now concerned with an aque
preferably dispersed beforehand by means of an aqueous
ous emulsion of synthetic elastomer which is suitable for
solution of a dispersing agent, such as for example sodium
the production of cross-linking agents, the synthetic elasto
methylene-bis-naphthalene sulphonate.
mers consisting of a copolymer of 2-chlorobutadi-1,3-ene
The emulsions according to the invention are excel
(chloroprene), an nap-ethylene carboxylic acid and an ad 40
lently suitable for the production of ?lms and impregna
ditional monomer which is capable of being copolym
tions on very different materials, such as for example
erised with the said components.
textiles, paper and leather. As already mentioned above,
Examples of ethylene carboxylic acids for the produc
they have the surprising property that after they have
tion of the said elastomers, are ou?-ethylenically unsatu
been applied to the support and after the water has
rated monocarboxylic acids, such as for example acrylic
'acid, methacrylic acid, as well as semiestcrs of fumaric 45 evaporated, they cross-link at room temperature. How
ever, it is of course also possible to accelerate the cross
ormaleic acid with saturated monohydric alcohols con
linking
by using elevated temperatures. The ?lms ob
taiuing l to 18 carbon atoms, such as methanol, propanol,
tained from these emulsions are further characterised by
hexanol, cyclohexanol, dodecanol, octadecanol, further
exceptionally good resistance to Weather in?uences, and
more cap-ethylene dicarboxylic acids or their anhydrides,
such as for example fumaric acid and maleic anhydride. 50 also good resistance to heat and chemicals, while at the
same time they approach the vulcanisates of natural rub
These carboxylic acids are advantageously incorporated
by polymerisation in quantities of 1/2 to 10% by weight
into the said elastomers.
>
Suitable as other copolymerisation components for the
production of the elastomers are conjugated diole?nes, 55
such as for example butadiene, isoprene, dichlorobutadi
one, as well as monovinyl compounds which are free
ber as regards elasticity properties and physical values.
In the following examples, the parts indicated are parts
by weight.
EXAMPLE 1
(a) 100 parts of water, 3 to 5 parts of surface-active
paraf?n sulphonate (emulsi?er) and 0.5 part of sodium
from carboxyl groups, such as styrene and acrylonitrile.
pyrop-hosphate are stirred in a pressure-tight vessel with
These copolymerisation components are advantageously
96 parts of chloroprene, which has been freed by Way of
used in quantities from about 2 to 10%, calculated on 60 an acid-activated bleaching earth column from the sta
the total monomers. Particularly suitable as cross-link
biliser, for example phenthiazine, and is heated, together
ing agent is zinc oxide. Further suitable agents are cal
with 4 parts of methacrylic acid and 0.5 part of n-dode
cium oxide, barium oxide, strontium oxide, magnesium
cylmercaptan, to a temperature of 40° C. Polymerisa
oxide, cadmium oxide, tin oxide, dibutyl-tin oxide or hy
tion starts after adding 0.0005 part of potassium per
drates thereof. ‘It is advisable to add these cross-linking 65 sulphate.
agents to the aqueous emulsions in quantities of about 2
With a conversion of 80%, the reaction is stopped by
toy10% by weight, calculated on the aforesaid copoly
adding 1 to 2 parts of Ibis-(Z-hydroxy-3-cyclohexyl~5
mers.
methylphenyl)-methane, which are dissolved in 1 to 2
‘
For the production of the copolymers, the said com
ponents are emulsi?ed in an aqueous medium with the
aid of the usual emulsi?ers and polymerised in the pres
parts of chloroprene and emulsi?ed with 2 to 4 parts of
va 2% emulsi?er solution.
The latex has gas removed therefrom in a stirrer-type
3,078,247
4
3
tioned in Example a are replaced by 91 parts of mono
Example 1 are replacedby 93.5 parts of chloroprene and
2.5 parts of vbutacliene and if the procedure adopted is
in other respects as previously described, there is, ob
tained a latex which cross-links satisfactorily with zinc
meric chloroprene and 5 parts of butadiene and if the
oxide and which provides the following strength values:
vessel‘ and it is concentrated to a solid content of about
48%.
(b) If the 96 parts of monomeric chloroprene men~
procedure is in other respects the same as that described
under a, a latex is obtained which has been prepared
with the, polymerisation speeds indicated in Table I. For
Table III
comparison purposes, the table includes the polymerisa
tion speeds of the latex according to Example a. It will 10
clearly be seen that the addition of *butadiene has con
siderably lowered the polymerisation speed, and experi
Latex without
zinc oxide
F
ence shows that this produces a more uniform polymer
structure with‘ the‘ monomers having very different
polymerisation speeds such as chloroprene and meth
acrylic acid.
Table l
[Latex according to Ex. 1a]
Metha-
Buta-
crylic
acid
diene
content,
ing
time,
Yield g. of solid
rubber in 100 g.
content,
percent,
hours
of latex
0
1
2
3
0
32 g.
40 g.
48 g.
percent
4
Latex with‘
zinc oxide
Vulcan. in hot air at 100° C.
D
F
D
100
l, 370
115
900
100 ,
l, 105
128
920
100
106
1, 320
1, 800
135
147
800
830
95
1, 390
146
850
110
1,310 '
139
820
108
1, 320
120
7
Operat
0
3%
EXAMPLE 3
If the 96 parts of monomeric chloroprene indicated in
25 Example 1 are replaced by'86 parts of chloroprene and
10 parts ofbutadiene and if the procedurefollowed is in
other respects as previously described, there is obtained
44 g.=80% yield
a latex which can be satisfactorily cross-linked with zinc
oxide andwhich, gives the-followingstrength values:
[Latex according to Ex. 1b]
4
5
0
1
2
3
4
5
30
0
21.5 g.
Table I V'
29 'g.
32 g.
34 g.
40 g.
42 g.
6
7
Latex without
zinc oxide
35
Latex with
zinc oxide
Vulcan. in hot air at 100° C.
44 g.=80% yield
F
D
51
63
51
63
05
02
75
After zinc oxide has been added to the latex obtained
according to Example 1a and after it has been cast to
F
1. 540
1, 500
1, 460
1, 460
l, 450
1, 435
1, 410
D
S8
100
115
119
118
118
120
080
040
920
020
895
865
810
form a ?lm with a thickness of approximately 0.8 mm.,
it is not possible for this latex to be cross-linked in a
satisfactorily reproducible manner at room temperature
or even at higher temperatures (up to 110° C.). The
reason for this is to be found in the non-uniform poly
EXAMPLE 4
mer structure (see Table II). In contrast hereto, when
operating in the same manner with the latex of Example
If the 96 parts of monomeric chloroprene indicated in
1b, there are obtained the strength values which are in
Example 1 are replaced by.91 parts of chloroprene and 5
dicated in Table II and which can be satisfactorily re 50 parts of acrylonitrile and if the procedure in other rc
produced, and these strength values are to be attributed
spects is as previously described, a latex is obtained which
to a uniform cross-linking. For latices containing ZnO,
can be cross-linked satisfactorily with zinc oxide‘ and which
5 g. of ZnO were used to 100 'g. of copolymer. The
has the following strength values:
values for the tearing strength (kg/cm?) are given un
der F and the values for elongation (percent) are given
under D.
Table V
Table II
Latex according to
Table 1, Ex. In
Vulcan. in hot
air at 100° 0.
Latex with- Latex with
out zine
ZnO
oxide
Latex without
zinc oxide
Latex according to
Table I, Ex. 1
Latex without zinc
oxide
F
Latex with
zinc oxide
F
D
F
D
F
D
F
87
93
100
100
104
108
110
950
940
930
930
890
830
800
92
04
97
100
107
108
110
880
870
860
845
840
790
750
05
08
100
100
108
118
128
1, 470
1, 340
1,320
1, 310
1, 250
1,210
1,200
187
192
197
200
210
210
212
Latex with
zinc oxide
00 Vulcan. in hot air at 100° C.
42
83
87
93
07
98
114.
D
870
970
880
870
860
850
S20
D
70
1, 54.0
1, 140
1,100
1, 050
1, 010
l 010
1, 000
F
D
13-1
140
141
146
148
150
126
880
860
8-10
830
820
820
315
EXAMPLE 5
If the 96 parts of monomeric chloroprene indicated in
Example 1 are replaced by 91 parts of chloroprene and 5
parts of dichlorobutadiene and if the procedure in other
If the 96 parts of monomeric chloroprene indicated in 75 respects is as previously described, a latex is obtained
EXAMPLE 2
3,078,247
6
5
with, said chloroprene being incorporated in said copoly
which can be satisfactorily cross-linked with zinc oxide
and which has the following strength values:
Table VI
Latex Without
zinc oxide
mer in a higher amount by weight than the sum of the
other two said monomers, the addition of zinc oxide being
made after adjusting said aqueous emulsion to a pH value
Latex with
zinc oxide
of about 6 to 6.5, the amount of zinc oxide being 2 to 10%
based on the amount of the emulsion, and the amount of
F
on the copolymer.
non-ionic stabilizer added being 1 to 5% by weight based
Vulcan. in hot air at 100° C.
F
D
D
2. The process of claim 1 wherein said synthetic elas
57
67
1, 385
1, 375
120
128
910
925
74
80
85
92
1, 335
1, 320
1, 260
1, 240
134
140
140
135
905
865
845
805
75
1, 210
120
760
10 tomer is a copolymer of 80 to 97.5 percent by weight of
chloroprene, 0.5 to 10 percent by weight of an alpha,
bcta-ethylenically unsaturated monocarboxylic acid, and
2 to 10 percent by weight of a monomer selected from the
group consisting of an additional conjugated diole?n
15 having 4 to 6 carbon atoms, styrene and acrylonitrile.
3. A stable aqueous emulsion of a synthetic elastomer
EXAMPLE 6
which is suitable for the production of cross-linked shaped
elements which contains 2 to 10 percent by weight, based
If the 96 parts of monomeric chloroprene indicated in
Example 1 are replaced by 91 parts of chloroprene and 5
on the total amount of emulsion, of zinc oxide as a cross
parts of dichlorobutadiene and if the procedure in other 20 linking agent, 1 to 5 percent, based on the copolymer, of
respects is as previously described, a latex is obtained
which can be satisfactorily cross-linked with zinc oxide
and which has the following strength values:
Table VII
Latex without
zinc oxide
D
109
114
113
113
120
124
120
1, 200
1, 160
1, 120
1, 100
1,100
1,080
1,020
F
D
149
157
160
174
184
180
160
a copolymer of chloroprene, an alpha,beta-ethylene
carboxylic acid, and an additional ole?nically unsaturated
monomer which is copolymerizable therewith, the chloro
25 prene content of said copolymer being higher, in amount
by weight, than the sum of the other two said monomers,
said emulsion having a pH value of about 6 to 6.5.
4. The aqueous emulsion of claim 3 wherein said syn
thetic elastomer is a copolymer of 80 to 97.5 percent by
30 weight of chloroprene, 0.5 to 10 percent by weight of an
Latex with
zinc oxide
Vulcan. in hot air at 100° C.
F
a non-ionic emulsi?er, and a synthetic elastomer which is
890
910
830
820
810
790
750
What is claimed is:
1. Process for the production of a stable aqueous emul
sion of a synthetic elastomer which is suitable for the
alpha,beta-ethylenically unsaturated monocarboxylic acid,
and 2 to 10 percent by weight of a monomer selected from
the group consisting of an additional conjugated diole?n
having 4 to 6 carbon atoms, styrene and acrylonitrile.
35
production of cross-linked shaped elements which com pp 0
prises adding zinc oxide and a non-ionic stabilizer to an
aqueous emulsion of a copolymer of chloroprene, an
alpha,beta-ethylene-carboxylic acid, and an ole?nically
unsaturated monomer which is copolymerizable there
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,710,292
2,859,193
2,959,821
Brown ______________ __ June 7, 1955
Kowalewski __________ _._ Nov. 4, 1958
Kolb ________________ __ Nov. 15, 1960
OTHER REFERENCES
Brown et al.: “Rubber World,” volume 130, No. 6,
September 1954, pages 784-788.
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