Note: Descriptions are shown in the official language in which they were submitted.
1 160798
The present invention relates to a process for the manu-
facture of a vinyl ester copolymer.
The manufacture of copolymers of vinyl ester and crotonic
acid is effected by polymerizing the monomers in bulk or in solution
in the presence of a radical-forming initiator and usually in the
presence of a regulator which is to adjust the molecular weight and
the polymerization rate. The known copolymers are suitable in the
form of alcoho~ic solutions as film-forming agents or binders in
hair sprays and hair setting lotions.
The known copolymers very frequently show the drawback
that they still contain a remainder of unreacted monomers and impur-
ities; this leads to an unpleasant smell and may cause skin irrita-
tion when using these substances. It is therefore the object of
the invention to manufacture vinyl ester/crotonic acid copolymers
with little smell, which do not exhibit the drawbacks of the known
copolymers.
~ he invention provides a process for the manufacture of a
copolymer of at least one vinyl ester and crotonic acid which com-
prises copolymerizing 70% to 90% by weight of the total amount of
vinyl ester with the total amount of crotonic acid in the presence
of a radical-forming initiator and a polymerization regulator, add-
ing the remainder of the vinyl ester to the polymerization reaction
mixture and completing the polymerization, mixing the polymer with
an entrainer which is an alkanol of 1 to 4 carbon atoms that may
contain up to 20% by weight of water and heating the resulting mix-
ture to vaporize at least a part of said alkanol and thereby distill
from said copolymer residual monomer and other volatile impurities.
The polymerization is optionally carried out in the
presence of a polyalkylene glycol.
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1 160798
Within the framework of the invention there are used as vinyl esters
above all vinyl esters of lower aliphatic monocarboxylic acids, especially com~
pounds of the formula
CH = CH - 0 - C0 - R
in which R is an alkyl radical of fram i, 2 or 3 carbon atcms, for example vinyl
aoe tate, vinyl propionate and vinyl butyrate. Preference is given in particular
to vinyl acetate. Instead of a single vinyl ester there may also be used a mix-
ture of several different vinyl esters.
As radical-forming initiators there are used peroxy oompounds and
aliphatic azo oompounds, for example diacetyl peroxide, dibenzoyl peroxide,
dilauroyl peroxide, diisopropyl percarbonate, tertiary butyl peroctoate, di-
tertiary butyl pe mxide and cumene hydroperoxide as well as azodiisobutyric acid
nitrile and azo dicarbonamide. The amount of the initiator is in the range of
fmm 0.01 to 5, preferably from 0.1 to 2 % by weight, calculated on the total
amount of the oompounds to be polymerized.
The polymerization is ocmmanly carried out in a tem~erature range of
from 25& below the boiling temperature of the reaction mixture to the boiling
temperature of the same. The temperature range of from 50 to 120&, preferably
from 70 to lOo&, is recornendel. It is advantageous to carry out the polymeriza-
tion under an inert gas atmosphere. As inert gases there may be used above allnitrogen and ncble gases, such as argon.
As regulators there may be mentioned aliphatic mercaptans, lower
aliphatic aldehydes and lower alkanols, especially aliphatic mercaptans having
from 4 to 16 c æbon
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atoms, for example n-butyl mercaptan, t-butyl mercaptan and
n-dodecyl mercaptan, furthermore, aliphatic aldehydes of
from 2 to 4 carbon atoms, for example acetaldehyde, pro
pionaldehyde and butyraldehyde, as well as alkanols of from
1 to 4 carbon atoms, for example methanol, ethanol, isopro-
panol and t-butanol.
A preferred embodiment of the process of the invention
is the execution of the polymerization in two stages,
according to which the main amount of the vinyl ester is at
first polymerized with the total amount of the crotonic
acid and optionally the total amount of the polyalkylene
glycol, and thereafter the polymerization is oompleted
after adding the remainder of vinyl ester. The weight
ratio of the monomers vinyl ester/crotonic acid that are
used altogether is in the range of from 100 : 1 to 100 :
20, preferably from 100 : 5 to 100 : 15. In the first
polymerization stage~ from 70 to 98 % by weight of the
total amount of the vinyl ester are normally used, prefe-
rably from 80 to 95 % by weight; in this process the
crotonic acid employed is polymerized almost completely.
The polymerization of the remaining 2 to 30, preferably
from 5 to 20 g by weight of the total amount of the vinyl
e~ter is then effected in the second stage, optionally while
adding an additional amount of initiator.
Arl essential feature of the process of the invention
is to be seen in the measure that upon completion of the
polymerization the remaining unreacted monomers and possible
volatile impurities, which have been introduced with the
29 monomers into the reaction mixture or have been formed in
... ..
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the course of the reaction, are removed from the reaction
mixture by way of distillation, so that the vinyl ester
copolymer extracted is obtained in a largely pure form and
with little smell. ~or this purpose it is advantageous to
use an entrainer in which the copolymer is at least partial-
ly soluble or swellable. As entrainers there are suitable
~B~ in particular lower alkanols of from 1 to ~ carbon atoms,
for example methanol, ethanol a~d isopropanol; the entrai-
ner may contain up to 20 % by weight of water. Said entrai-
ner is employed in an amount of from 5 to 50, preferably 10to 30 ~ by weight, calculated on the copolymer. It is
advantageous to mix the entrainer with the copolymer which
upon completion of the polymerization is present in a
melted form, however, it may also be added to the reaction
mixture before or during the polymerization, if it does not
disturb the reaction. The entrainer which is removed by
di~tillation may be used several times without working-up.
If a vinyl ester and crotonic acid are used as the
only polymerizable compounds, the process of the invention
leads to copolymers with a statistical distribution of the
monomer units However, if a polyalkylene glycol is addi-
tionally employed, graft copolymers are obtained.
As polyalkylene g~ycols there are suitable above all
polyalkylene glycols with an average molecular weight
(numerical average) of from 106 to 25,000, preferably from
1,000 to 15,000, i.e. oligomer compounds and higher molecu-
lar weight polymers of aliphatic diols or corresponding cyc-
lic ethers. As oligomers there may be mentioned diethylene
glycol, triethylene glycol, tetraethylene glycol as well
as dipropylene glycol and tripropylene glycol; as polyrners
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there are mentioned especially polyethylene glycol and
polypropylene glycol. Copolymers of different cyclic
ether~, especially of ethylene oxide and 1,2-propylene
oxide, may also be used.
The po].ymers obtained according to the invention are
suitabl~ as starting materials for adhesives and especially
for hair lacquers, hair setting lotions and hair sprays.
In the field ol cosmetics they are commonly used in the
form of diluted solutions in mixtures of water and lower
a].cohols, especially ethanol or isopropanol. The polymer
content of solutions of this kind is generally in the range
of from 2 to 5 % by weight.
The following Examples illustrate the invention and
show the advantages over the state of the art, which may be
seen from the compariqon examples. All percentages relate
to the weight; ~'ppm" means "parts per million~. The mono-
mer content of the polymer solution i8 determined in each
oa3~ by way of gas chromatography.
E X A M P L E 1: .
15 Per cent of a mixture of 56 kg of vinyl acetate,
6.3 kg of crotonic acid, 1.3 kg of dibenzoyl peroxide and
0.25 kg of acetaldehyde are placed into a stirring vessel
having a cap~city of 100 liters and being flushed with
nitrogen, the vessel being provided with a reflux condenser,
a jacket heating and cooling, and said mixture is heated to
reflux temperture (about 70C). In the course of 7 hours
the remaining 85 ~ of the above mixture are uniformly added,
in which process the polymerization heat is carried off by
29 the jacket cooling in a manner that a slight reflux is
.
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maintained and the internal temperature rises slowly to
90 to 95C. Subsequently 7 kg of vinyl acetate are added
in doses in the course of 1 hour.
After having been heated for 2 hours at 95C, the
reaction mixture is distilled under reduced pressure (about
70 mbars) for 5 hours. The remaining polymer melt is let
off into a trough and is allowed to cool therein the room
temperature and solidifies. From the polymer thus obtained,
a 60 % solution in ethanol is prepared; it contains 65 ppm
of crotonic acid and 1,210 ppm of vinyl acetate. This
solution is concentrated to a solids content of 70 % by
removing ethanol by distillation, thereafter it is diluted
again with ethanol to a content of 60 %; it now contains 60
ppm of crotonic acid and 340 ppm of vinyl acetate and is
almost odorless.
E X A M P L E 2:
.. ... . _
The process is carried out as has been described in
Example l, however, the starting mixture is composed of 49
kg of vinyl acetate, 6.3 kg of crotonic acid, l.l kg of
dibenzoyl peroxide and 0.25 kg of acetaldehyde, and the
introduction of the 85 ~ portion takes 6 hours; in the
second stage, 14 kg of vinyl acetate, in which 0.24 kg of
dibenzoyl peroxide is dissolved, are added in doses in the
course of 2 hours.
The 60 % solution in ethanol prepared from the polymer
obtained is concentrated to a solids content of 80 % by
distilling off ethanol, and thereafter said mixture is
again diluted with ethanol to a content of 60 ~. The
29 solution then contains 27 ppm of crotonic acid and 65 ppm
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of vinyl acetate and is odorless.
E X A M P L E 3:
The process is carried out as has been described in
Example 1, however, the starting mixture consists of 42 kg
of vinyl acetate, 6.3 kg of crotonic acid, 1 kg of dibenzoyl
peroxide and 0.25 kg of acetaldehyde, and the introduction
of the 85 % portion takes 5 hours; in the second stage,
21 kg of vinyl acetate, in which 0.34 kg of dibenzoyl
peroxide is dissolved, are added in doses within 3 hours.
The 60 % solution in ethanol prepared from the polymer
obtained contains 11 ppm of crotonic acid and 1.215 ppm of
vinyl acetate. It is concentrated to a solids content of
90 ~ by distilling off ethanol, and subsequently it is
diluted again to a content of 60 % with ethanol. This
solution contains now less than 10 ppm of crotonic acid
and less than 20 ppm of vinyl acetate and is odorless.
OMPARISON EXAMPLE 1.
15 Per ¢ent of a mixture of 63 kg of vinyl acetate,
6.3 kg of crotonic acid, 1.3 kg of dibenzoyl peroxide and
0.25 kg of acetaldehyde are placed into the vessel describ-
ed in Example 1 and the mixture is heated to reflux tempe-
ratùre (about 70C). In the course of 8 hours the remain-
ing 85 % of the above-mentioned mixture are uniformly added,
the rise in temperature being regulated according to
Example 1.
After having been heated for another 2 hours at 9:jC,
the reaction mixture is distilled under reduced pres~ure
(about 70 mbars) for 5 hours. The remaining polymer melt
29 is let off into a trough, where it is allowed to cool to
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room temperature and solidi~ies. From the polymer obtained,
a 60 % solution in ethanol is prepared; the solution
having a strong smell contains 186 ppm of crotonic acid and
1.260 ppm of vinyl acetate.
E X A M P L E 4:
6 Kilograms of polyethylene glycol having an average
molecular weight of 4,000 and 15 % of a mixture of 48 kg of
. vinyl acetate, 4.8 kg of crotonic acid, 1.2 kg of dibenzoyl
peroxide and 0.25 kg of acetaldehyde are placed into the
vessel described in Example 1, and the mixture is heated to
reflux temperature (about 70C). In the course of 6
hours the remaining 85 % of the above-mentioned mixture
are uniformly added, the rise in temperature being regulat-
ed according to Example 1. Subsequently 12 kg of vinyl
acetate, in which 0.3 kg of dibenzoyl peroxide is dissolved,
are added in doses in the second stage within 2 hours.
After having been heated for another 2 hours at 95C,
the reaction mixture is distilled for 5 hours under reduced
pressure (about 70 mbars). The remaining polymer melt is
~et off into a trough and is allowed to cool therein to
room temperature and solidifies. From the polymer obtained
a 60 % solution is prepared in an isopropanol/water mixture
(87~13), which contains 35 ppm of crotonic acid and 1,350
ppm of vinyl acetate. This solution is concentrated to a
solids content of 80 % by distilling off the solvent and is
then diluted a~ain to a content of 60 % with the sarne
solvent; it then contains 33 ppm of crotonic acid ..nd
60 ppm of vinyl acetate and is almost free from any smell.
. . .
.
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E X A M P L E 5:
The process is ^arried out as has been described in
Example 4, however, while introducing 6 kg of polypropylene
glycol having an average molecular weight of 2,000 and 4 kg
of isopropanol, and the starting mixture consists of 48 kg
of vinyl acetate, 4,8 kg of crotonic acid and 1.2 kg of
tertiary butyl peroctoate; the introduction of the 85 %
portion takes 6 hours. In the second stage, 12 kg of vinyl
acetate, in which 0.3 kg of tertiary butyl peroctoate has
been dissolved, are added in doses in the course of 2 hours.
The 60 % solution in isopropanol/water (87/13) prepar-
ed from a sample of the polymer obtained contains 32 ppm of
crotonic acid and 970 ppm o~ vinyl acetate. Thereafter 600
g of the solid polymer are melted together with 600 g of
i~opropanol. Subse~uently 252 g of isopropanol are distill-
ed off, and 52 ml of water are added, while stirring. The
60 % solutlon thus obtained contains 30 ppm of crotonic
acid and 55 ppm of vinyl acetate.
COMAPRISON EXAMPLE 2
6 Kilograms of polyethylene glycol having an average
molecular weight of 4,000 and 15 % of a mixture of 60 kg of
vinyl acetate, 4.8 kg of crotonic acid, 1.5 kg of dibenzoyl
peroxide and 0.25 kg Or acetaldehyde are placed into the
vessel described in Example 1, and the mixture is heated to
reflux temperature (about 70C). In the course of 8 hours,
the remaining 85 ~ of the above-mentioned mixture are uni-
formly added, the rise in temperature being regulated in
accordance with Example 1.
29 After having been heated for another 2 hours at 95C,
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the reaction mixture is distilled for 5 hours under reduced
pressure (about 70 mbars). The remaining polymer melt is
let off into a trough, where it is allowed to cool to room
temperature and solidifies. Erom the polymer thus obtained,
a 60 % solution in an isopropanol/water mixture (87/13) is
prepared, which solution contains 197 ppm of crotonic acid
and 1.320 ppm of vinyl acetate.
COMPARISON EXAMPLE 3
The process is carried out as has been described in
Comparison Example 2, however, while using instead of poly-
ethylene glycol polypropylene glycol having an average
molecular weight of 2,000, and as starting mixture there is
used a mixture of 60 kg of vinyl acetate, 4.8 kg of crotonic
acid and 1.5 kg of tertiary butyl peroctoate.
The 60 % solution in isopropanol/water (87/13) prepar-
ed from the polymer obtained contains 210 ppm of crotonic
acid and 1,130 ppm of vinyl acetate.
