The present invention relates to an aqueous composition in the form of an
emulsion comprising at least one peroxydicarbonate and at least one peroxyester,
preferably at least one hydroxyperoxyester.
5 The invention also relates to the use of an aqueous composition comprising
the mixture of organic peroxides, as defined above, for the polymerization or
copolymerization of one or more ethylenically unsaturated monomers, which are
preferably halogenated, and more preferentially vinyl chloride.
The present invention also relates to a halogenated vinyl polymer obtained by
10 polymerization of at least one halogenated ethylenically unsaturated monomer in the
presence of the mixture of organic peroxides as defined above.
Organic peroxides, in liquid or solid form, are commonly used as initiators
for the polymerization of ethylenically unsaturated monomers for the synthesis of
various types of polymers.
15 However, their use frequently presents a certain number of problems.
Specifically, organic peroxides usually constitute highly unstable species since they
decompose relatively easily under the action of a slight input of heat, of mechanical
energy (friction or impact) or of incompatible contaminants. Thus, in the event of
uncontrolled elevation of their storage temperature, some organic peroxides can
20 undergo an autoaccelerated exothermic decomposition which can result in fires and/or
violent explosions. In addition, under these conditions, some of these organic peroxides
can release combustible vapors that are capable of reacting with any source of ignition
which can drastically increase, or even accelerate, the risks of violent explosion. As a
result, it is important to take appropriate precautionary measures in terms of safety
25 during the storage and transportation of organic peroxides.
In order to overcome these drawbacks, organic peroxides are notably
packaged in the form of aqueous emulsions comprising antifreezes. Thus, the presence
of water makes it possible both to absorb and to dissipate the energy generated in the
event of exothermic decompositions of organic peroxides, while the role of the
30 antifreeze is to keep the emulsion in liquid form, at temperatures of less than -10°C,
generally of less than -15°C, which makes it possible to limit the risks of an involuntary
exothermic decomposition of organic peroxides.
The aqueous emulsions generally also contain an emulsifier having the
advantage of lowering the interfacial tension between the aqueous phase and the
35 organic peroxide for the purpose of facilitating the dispersion of the peroxide in the
form of droplets and of maintaining the size of said droplets over time. This is because,
over time, the peroxide droplets can agglomerate together, bringing about an increase
2
in their average size and in their maximum size which can result, in some cases, in total
or partial phase separation and consequently in overall destabilization of the emulsion.
In view of the above, aqueous organic peroxide emulsions must therefore be
stable for safety reasons not only during their production but also for a relatively long
5 period of time corresponding to their transportation and storage before being used as
polymerization initiators. For this purpose, the organic peroxide droplets must mainly
have an average size and a maximum size that are small and stable over time.
Moreover, it is essential to obtain homogeneous emulsions. Specifically, the
use of non-homogeneous organic peroxide emulsions, i.e. emulsions having a
10 significant difference in organic peroxide concentration distributed between the upper
and lower part of the aqueous phase, can also give rise to unpredictable differences in
initiator concentrations in the polymerization reactor.
In addition, the steps of discharging the emulsion in intermediate storage silos,
of pumping and of introduction of an organic peroxide emulsion into a polymerization
15 reactor are steps that are important for the quality of the polymer obtained and the
reliability of the polymerization process. These handling steps must be performed as
rapidly as possible. To do this, it is important for the peroxide emulsion to have a low
viscosity so that the flow of the emulsion is facilitated as much as possible. Thus, an
organic peroxide emulsion should have a maximum dynamic viscosity around 500-700
mPa.s at low temperature, typically of the order of -10°C for a shear rate of 100 s-1
20 .
The dynamic viscosity measurements are performed using coaxial cylinders that create
shear, for example according to the standard DIN 53019.
However, a person skilled in the art knows that, for this type of emulsion,
seeking to reduce the size of the droplets contributes toward increasing the viscosity
25 (see paragraph 1.4 of the article by J.P. Canselier and M. Poux, “Emulsification
processes - Mechanism of emulsion formation” Techniques de l’Ingénieur J2 152,
pages 1-12, publication of 10 June, 2004).
More precisely, the fact of seeking to decrease the size of the organic peroxide
droplets and to reduce, at the same time, the viscosity of the organic peroxide
30 emulsions leads to conflicting effects that are difficult to reconcile.
In order to address all of these issues, aqueous organic peroxide emulsions
comprising at least one organic peroxide, at least one particular nonionic surfactant as
emulsifier, for example an alkoxylated fatty alcohol and/or an alkoxylated, optionally
hydrogenated plant or animal oil, and antifreezes such as alcohols, notably methanol,
35 have already been developed in the prior art.
However, such aqueous emulsions of organic peroxides have not proven to be
sufficiently stable over time. Indeed, it has been observed that the average size and the
3
maximum size of the peroxide droplets increased significantly over a relatively short
period of time to the point of resulting, in some cases, to complete phase separation of
the emulsion. Some of these emulsions have, for example, been found to be unstable
in less than 6 months, or even in less than 3 months, at temperatures of about -20°C or
5 -25°C, which naturally makes their transport and storage difficult to undertake in total
safety.
Thus, one of the aims of the present invention is to propose a composition in
the form of an aqueous emulsion of organic peroxide which is stable and homogeneous
over time, intended to be used as polymerization initiators, which does not have the
10 drawbacks described previously in terms of the safety and quality of the product
obtained.
In particular, one of the aims of the present invention is to propose an aqueous
organic peroxide emulsion composition notably having a low average droplet size,
notably of less than 10 µm, preferably less than 5 µm, a homogeneous size distribution,
15 a homogeneous distribution of the organic peroxide and a maximum droplet size of
less than 20 µm, or even less than 15 µm, in particular less than 5 µm, which is stable
over time, for example over a period of six months, while complying with the required
conditions as regards viscosity and flow time of the emulsion.
A subject of the present invention is thus notably an aqueous organic peroxide
20 emulsion composition comprising:
- one or more organic peroxides of formula (I):
in which formula (I) R1
and R2
, which may be identical or different, represent
25 a linear, branched or cyclic C1-C20 alkyl group which may comprise, and is preferably
interrupted with, one or more heteroatoms, preferably one or more oxygen atoms;
- one or more organic peroxides of formula (II):
4
in which formula (II) R3
and R4
, which may be identical or different, represent
a linear, branched or cyclic C1-C20 alkyl group which may comprise, and is preferably
5 interrupted with, one or more heteroatoms, preferably one or more oxygen atoms,
and/or is optionally substituted with one or more hydroxyl groups.
The composition according to the invention thus has the advantage of being
stable for a period of 6 months at a temperature of about -20°C or -25°C.
In particular, the composition according to the invention is an aqueous
10 emulsion notably having a low average droplet size, preferably of less than 10 µm,
more preferably less than 5 µm, a homogeneous size distribution, a homogeneous
distribution of the organic peroxide and a maximum droplet size of less than 20 µm, or
even less than 15 µm, which is stable over time, without the appearance of gel or phase
separation in the organic and aqueous phases.
15 More precisely, the composition according to the invention has an average
droplet size (d50) of less than 10 µm after production or during storage at a temperature
of -20°C for a period of six months; the maximum droplet size (d100) not exceeding 20
µm during this period.
Moreover, the composition according to the invention has the advantage of
20 being stable for a period of 6 months at a temperature of about -20°C or -25°C.
The term “homogeneous” means that the organic peroxides have a small
concentration gradient. In other words, the samples taken at different locations in the
emulsion have a similar concentration of organic peroxides (i.e. preferably have less
than 5% absolute difference, preferably less than 3% absolute difference, more
25 preferentially less than 2% absolute difference). Thus, advantageously, when the
composition according to the invention is packaged in a storage container, the
difference in organic peroxide concentration distributed between the upper part and the
lower part of the container remains less than 3%, or even less than 2%, over time,
notably over a period of 6 months, which makes it possible to guarantee the
30 reproducibility of the polymerization rates.
5
This thus allows the composition according to the invention to be taken either
from the top or the bottom of the vessel to initiate polymerization of ethylenically
unsaturated monomers at similar and reproducible rates.
As a result, the composition according to the invention remains effective over
5 time.
Furthermore, the composition according to the invention has a low viscosity,
preferably less than 850 mPa.s, preferably less than 700 mPa.s, more preferably less
than 500 mPa.s, which allows a very short flow time.
The dynamic viscosity measurements may be performed using coaxial
10 cylinders that create shear, for example according to the standard DIN 53019.
Thus, the composition according to the invention can be safely transported
and stored in polymer production units and lead to polymeric materials of good quality.
By way of clarification, the composition according to the invention makes it
possible to improve the transparency of the final polymeric material.
15 A subject of the invention is also the use of an aqueous composition
comprising the mixture of organic peroxides as defined above for the polymerization
or copolymerization of one or more ethylenically unsaturated monomers, in particular
vinyl monomers, preferably halogenated vinyl monomers, and more preferentially
vinyl chloride.
20 The aqueous composition comprising the mixture of organic peroxides may
thus be used as polymerization initiators for the synthesis of polymers or copolymers
obtained from one or more ethylenically unsaturated monomers.
Thus the composition is compatible with the polymerization or
copolymerization of ethylenically unsaturated monomers, preferably vinyl monomers.
25 In addition, the invention also relates to a halogenated vinyl polymer obtained
by polymerization of at least one halogenated ethylenically unsaturated monomer in
the presence of the aqueous composition containing the mixture of organic peroxides
as described above.
Other features and advantages of the invention will become more clearly
30 apparent on reading the description and the examples that follow.
In the text hereinbelow, unless otherwise indicated, the limits of a range of
values are included in that range.
The expression “at least one” is equivalent to the expression “one or more”.
35 Composition
6
As indicated previously, the composition according to the invention
comprises one or more organic peroxides of formula (I):
in which formula (I) R1
and R2
5 , which may be identical or different, represent
a linear, branched or cyclic C1-C20 alkyl group which may comprise, and is preferably
interrupted with, one or more heteroatoms, preferably one or more oxygen atoms.
Preferably, R1
and R2
, which may be identical or different, represent a linear,
branched or cyclic C1-C16, more preferentially C3-C12, in particular C3-C10, alkyl group
10 which may comprise, and is preferably interrupted with, one or more heteroatoms,
preferably one or more oxygen atoms.
Preferably, R1
and R2
, which may be identical or different, represent a linear
C1-C16, more preferentially C3-C12, in particular C3-C10, alkyl group which may
comprise, and is preferably interrupted with, one or more heteroatoms, preferably one
15 or more oxygen atoms.
Preferably, R1
and R2
, which may be identical or different, represent a
branched C1-C16, more preferentially C3-C12, in particular C3-C10, alkyl group which
may comprise, and is preferably interrupted with, one or more heteroatoms, preferably
one or more oxygen atoms.
Preferably, R1
and R2
20 , which may be identical or different, represent a cyclic
C1-C16, more preferentially C3-C12, in particular C3-C10, alkyl group which may
comprise, and is preferably interrupted with, one or more heteroatoms, preferably one
or more oxygen atoms.
For the purposes of the present invention, the term “cyclic alkyl group” means
25 that the alkyl group includes a ring, preferably an aromatic ring, comprising 5 or 6 ring
members.
Preferably, the heteroatom is an oxygen atom.
Preferably, R1
and R2
are identical and represent a linear or branched,
preferably branched, C2-C16, in particular C3-C12, more preferentially still C3-C10, alkyl
30 group.
7
Preferentially, R1
and R2
are identical and represent a linear or branched,
preferably branched, C2-C8 alkyl group.
The organic peroxides of formula (I) are preferably chosen from the group
consisting of bis(2-ethylhexyl) peroxydicarbonate, di(sec-butyl) peroxydicarbonate,
5 bis(1-methylheptyl) peroxydicarbonate, di(n-propyl) peroxydicarbonate, bis(3-
methoxybutyl) peroxydicarbonate, diethyl peroxycarbonate and mixtures thereof,
preferably bis(2-ethylhexyl) peroxydicarbonate and di(sec-butyl) peroxydicarbonate.
Advantageously, the organic peroxide of formula (I) is chosen from the group
consisting of bis(2-ethylhexyl) peroxydicarbonate, sold under the trade name
10 Luperox® 223, and di(sec-butyl) peroxydicarbonate, sold under the trade name
Luperox® 225.
As indicated previously, the composition according to the invention also
comprises one or more organic peroxides of formula (II):
15
in which formula (II) R3
and R4
, which may be identical or different, represent
a linear, branched or cyclic C1-C20 alkyl group which may comprise, and is preferably
interrupted with, one or more heteroatoms, preferably one or more oxygen atoms,
20 and/or is optionally substituted with one or more hydroxyl groups.
Preferably, R3
and R4
, which may be identical or different, represent a linear
or branched C7-C20, preferably C7-C16 and in particular C7-C10 alkyl group which may
comprise, and is preferably interrupted with, one or more heteroatoms, preferably one
or more oxygen atoms, and/or is optionally substituted with one or more hydroxyl
25 groups.
Preferably, R3
and R4
, which may be identical or different, represent a linear
C7-C20 alkyl group, preferably a C7-C16 alkyl group, in particular a C7-C10 alkyl group,
which may comprise, and is preferably interrupted with, one or more heteroatoms,
preferably one or more oxygen atoms, and/or is optionally substituted with one or more
30 hydroxyl groups.
Preferably, R3
and R4
, which may be identical or different, represent a
branched C7-C20, preferably a C7-C16 alkyl group, in particular a C7-C10 alkyl group,
8
which may comprise, and is preferably interrupted with, one or more heteroatoms,
preferably one or more oxygen atoms, and/or is optionally substituted with one or more
hydroxyl groups.
Preferably, R3
and R4
, which may be identical or different, represent a cyclic
5 C7-C20 alkyl group, preferably a C7-C16 alkyl group, in particular a C7-C10 alkyl group,
which may comprise, and is preferably interrupted with, one or more heteroatoms,
preferably one or more oxygen atoms, and/or is optionally substituted with one or more
hydroxyl groups.
For the purposes of the present invention, the term “cyclic alkyl group” means
10 a linear or branched alkyl group also including a ring, preferably an aromatic ring,
preferably comprising 5 or 6 ring members.
In other words, for the purposes of the present invention, a cyclic alkyl group
includes a linear or branched, preferably C2-C4, alkyl group and a ring, preferably an
aromatic ring, preferably comprising 5 or 6 ring members.
15 Preferably, the cyclic alkyl group comprises a branched, preferentially C2-C4,
alkyl group and an aromatic ring preferably comprising 5 or 6 ring members.
Preferably, R3
and R4
, which may be identical or different, represent an alkyl
group, as defined previously, which may be interrupted with one or more heteroatoms,
preferably one or more oxygen atoms, and/or is optionally substituted with one or more
20 hydroxyl groups.
Preferably, R3
and R4
, which may be identical or different, represent a linear,
branched or cyclic C1-C20 alkyl group which may be optionally substituted with one or
more hydroxyl groups.
Preferably, R3
represents a linear or branched C7-C20, preferably C7-C16, in
25 particular C7-C10, alkyl group, which may comprise, and is preferably interrupted with,
one or more heteroatoms, preferably one or more oxygen atoms, and R4
represents a
linear or branched C1-C7, preferably C2-C6, alkyl group which is optionally substituted
with one or more hydroxyl groups, or a cyclic C7-C16, in particular C7-C10, alkyl group.
Preferably, R3
represents a branched C7-C20, preferably C7-C16, in particular
30 C7-C10, alkyl group which may comprise, and is preferably interrupted with, one or
more heteroatoms, preferably one or more oxygen atoms, and R4
represents a branched
C1-C7, preferably C2-C6, alkyl group optionally substituted with one or more hydroxyl
groups.
Preferably, the heteroatom is an oxygen atom.
35 Preferably, in formula (II):
- R
3
represents a linear, branched or cyclic, preferably branched, C7-C20
alkyl group, preferably a C7-C16 alkyl group, in particular a C7-C10 alkyl
9
group, which may be interrupted with one or more oxygen atoms,
preferably one oxygen atom;
- R
4
represents:
i) a linear or branched, preferably branched, C7-C20 alkyl group,
5 preferably a C7-C16 alkyl group, in particular a C7-C10 alkyl group,
which may be interrupted with one or more oxygen atoms, preferably
one oxygen atom;
ii) a linear or branched, preferably branched, C1-C7, preferably C2-C6,
alkyl group optionally substituted with one or more hydroxyl groups;
10 or
iii) a cyclic C7-C10, in particular cyclic C9, alkyl group.
Preferentially, in formula (II), R3
represents a linear or branched, preferably
branched, C7-C20 alkyl group, preferably a C7-C16 alkyl group, in particular a C7-C10
alkyl group.
15
Preferentially, in formula (II), R4
represents:
- a linear or branched, preferably branched, C1-C7, preferably C2-C6, in
particular C4 or C6, alkyl group optionally substituted with one or more hydroxyl
groups,
20 - a cyclic C7-C10, in particular C9, alkyl group.
Preferentially, in formula (II), when R4
represents a cyclic C7-C10 alkyl group,
R
4
then includes a linear or branched, preferably branched, C2-C4, in particular C3,
alkyl group, and a ring, preferably an aromatic ring, preferably comprising 5 or 6 ring
members.
Even more preferentially, R4
25 represents a linear or branched, preferably
branched, C1-C7, preferably C2-C6, in particular C6, alkyl group substituted with one
or more hydroxyl groups, in particular one hydroxyl group.
Advantageously, in formula (II):
- R
3
represents a linear or branched, preferably branched, C7-C20 alkyl
30 group, preferably a C7-C16 alkyl group, in particular a C7-C10 alkyl group.
- R
4
represents a linear or branched, preferably branched, C1-C7, preferably
C2-C6, alkyl group optionally substituted with one or more hydroxyl
groups.
The organic peroxides of formula (II) are preferably chosen from the group
35 consisting of α-cumyl peroxyneodecanoate, α-cumyl peroxyneoheptanoate, 2,4,4-
trimethylpent-2-yl peroxyneodecanoate, tert-butyl peroxy(n-heptanoate), tert-butyl
peroxyneodecanoate, α-cumyl peroxy(n-heptanoate), tert-amyl peroxy(n-heptanoate),
10
tert-butyl peroxyneoheptanoate, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane,
tert-amyl peroxy(2-ethylhexanoate), tert-butyl peroxy(2-ethylhexanoate), 1,1,3,3-
tetramethylbutyl peroxy(2-ethylhexanoate), hydroxyperoxyesters, tert-amyl
peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, 1,1,3,3-
5 tetramethylbutyl peroxypivalate, tert-hexyl peroxyneodecanoate, tert-hexyl
peroxypivalate and mixtures thereof.
Preferably, the peroxyesters are chosen from the group consisting of
hydroxyperoxyesters.
The hydroxyperoxyesters are advantageously chosen from the group
10 consisting of 4-hydroxy-2-methylpentyl peroxyneodecanoate, 4-hydroxy-2-
methylpentyl peroxyneoheptanoate, 4-hydroxy-2-methylpentyl peroxy(2-
ethylhexanoate), 4-hydroxy-2-methylpentyl peroxy(2-phenylbutyrate), 4-hydroxy-2-
methylpentyl peroxy(2-phenoxypropionate), 4-hydroxy-2-methylpentyl peroxy(2-
butyloctanoate), 4-hydroxy-2-methylpentyl peroxyneohexanoate, 4-hydroxy-2-
15 methylpentyl peroxyneotridecanoate, 4-hydroxy-2-methylhexyl peroxyneohexanoate,
4-hydroxy-2-methylhexyl peroxyneodecanoate, 5-hydroxy-1,3,3-trimethylcyclohexyl
peroxyneodecanoate, 4-hydroxy-2,6-dimethyl-2,6-di(neohexanoylperoxy)heptane, 4-
hydroxy-2,6-dimethyl-2,6-di(neodecanoylperoxy)heptane, 3-hydroxy-1,1-
dimethylbutyl peroxy(2-ethylhexanoate), 3-hydroxy-1,1-dimethylbutyl
20 peroxyneodecanoate, 3-hydroxy-1,1-dimethylbutyl peroxyneoheptanoate and
mixtures thereof, preferably 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate.
Preferably, the organic peroxide of formula (II) is chosen from the group
consisting of tert-butyl peroxyneodecanoate, tert-amyl peroxyneodecanoate, α-cumyl
peroxyneoheptanoate, hydroxyperoxyesters and mixtures thereof.
25 Preferably, the organic peroxide of formula (II) is chosen from the group
consisting of 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate, sold under the trade
name Luperox® 610 by Arkema, α-cumyl peroxyneoheptanoate, sold under the trade
name Luperox® 188, tert-amyl peroxyneodecanoate, sold under the trade name
Luperox® 546, and tert-butyl peroxyneodecanoate, sold under the trade name
30 Luperox® 10 by Arkema, and mixtures thereof.
Preferably, the organic peroxide of formula (II) is chosen from the group
consisting of 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate, sold under the trade
name Luperox® 610 by Arkema, and tert-butyl peroxyneodecanoate, sold under the
trade name Luperox® 10 by Arkema, and mixtures thereof.
35 Advantageously, the organic peroxide of formula (II) is 3-hydroxy-1,1-
dimethylbutyl peroxyneodecanoate, sold under the trade name Luperox® 610 by
Arkema.
11
The organic peroxide(s) of formula (I) and the organic peroxide(s) of formula
(II) are preferentially present in a concentration ranging from 40% to 70% by weight
relative to the total weight of the composition, preferably ranging from 40% to 65% by
weight relative to the total weight of the composition, more preferentially present in a
5 concentration ranging from 40% to 60% by weight relative to the total weight of the
composition. In other words, the concentration of the organic peroxide(s) of formula
(I) plus the concentration of the organic peroxide(s) of formula (II) preferentially
represent a concentration ranging from 40% to 70% by weight relative to the total
weight of the composition, preferably ranging from 40% to 65% by weight relative to
10 the total weight of the composition, more preferentially ranging from 40% to 60% by
weight relative to the total weight of the composition.
Preferably, the total concentration of organic peroxides in the composition
ranges from 40% to 70% by weight relative to the total weight of the composition,
preferably from 40% to 65% by weight relative to the total weight of the composition,
15 more preferentially from 40% to 60% by weight.
Preferably, only the organic peroxides of formulae (I) and (II) are present in
the composition.
Preferably, the weight ratio of organic peroxide(s) of formula (I)/organic
peroxide(s) of formula (II) ranges from 1/99 to 99/1, preferentially from 2/98 to 98/2.
20 According to another embodiment, the weight ratio of organic peroxide(s) of
formula (I)/organic peroxide(s) of formula (II) ranges from 10/90, in particular from
20/80, to 50/50.
According to another embodiment, the weight ratio of organic peroxide(s) of
formula (I)/organic peroxide(s) of formula (II) ranges from 99/1, in particular from
25 97/3, in particular from 90/10 and preferentially from 80/20 to 50/50.
The organic peroxides of formulae (I) and (II) advantageously have a one hour
half-life temperature of less than or equal to 90°C, preferably of less than 90°C.
Furthermore, the organic peroxides of formulae (I) and (II) advantageously
have a storage temperature below 0°C.
30 The organic peroxides of formulae (I) and (II) are advantageously liquid at
the storage temperature, preferably at a storage temperature below 0°C, measured at
atmospheric pressure.
Preferably, the composition according to the invention comprises:
- one or more organic peroxides of formula (I):
12
in which formula (I) R1
and R2
are identical and represent a linear or branched,
preferably branched, C1-C16, in particular C3-C12, even more preferentially C3-C10,
alkyl group;
5 - one or more organic peroxides of formula (II):
in which formula (II):
- R
3
represents a linear, branched or cyclic, preferably branched, C7-C20
10 alkyl group, preferably a C7-C16 alkyl group, in particular a C7-C10 alkyl
group, which may comprise, and is preferably interrupted with, one or
more oxygen atoms, preferably one oxygen atom;
- R
4
represents:
i) a linear or branched, preferably branched, C7-C20 alkyl group,
15 preferably a C7-C16 alkyl group, in particular a C7-C10 alkyl group,
which may comprise, and is preferably interrupted with one or more
oxygen atoms, preferably one oxygen atom;
ii) a linear or branched, preferably branched, C1-C7, preferably C2-C6,
alkyl group optionally substituted with one or more hydroxyl groups;
20 or
iii) a cyclic C7-C10, in particular cyclic C9, alkyl group.
Advantageously, in accordance with this preferred embodiment, in formula
(I), R1
and R2
are identical and represent a linear or branched, preferably branched, C2-
25 C8 alkyl group.
Advantageously, in accordance with this preferred embodiment, R3
and R4
are
different.
13
Even more advantageously, in accordance with this preferred embodiment, in
formula (II):
- R
3
represents a linear or branched, preferably linear, C7-C20 alkyl group,
preferably a C7-C16 alkyl group, in particular a C7-C10 alkyl group;
- R
4
5 represents a linear or branched, preferably branched, C1-C7, preferably
C2-C6, alkyl group optionally substituted with one or more hydroxyl
groups.
Advantageously again, in accordance with this preferred embodiment, in
formula (II), R4
10 represents a linear or branched, preferably branched, C1-C7, preferably
C2-C6, alkyl group optionally substituted with one or more hydroxyl groups.
Advantageously again, in accordance with this preferred embodiment, in
formula (II), R4
represents a linear or branched, preferably branched, C1-C7, preferably
C2-C6, alkyl group substituted with one or more hydroxyl groups, in particular one
15 hydroxyl group.
More advantageously, the composition according to the invention comprises
bis(2-ethylhexyl) peroxydicarbonate, in particular sold under the trade name Luperox
® 223, or di-sec-butyl peroxydicarbonate, in particular sold under the trade name
Luperox ® 225, and hydroxyperoxyesters of formula (II), preferably 3-hydroxy-1,1-
20 dimethylbutyl peroxyneodecanoate, in particular sold under the trade name Luperox ®
610.
Preferably, the composition may comprise one or more antifreezes
preferentially chosen from the group consisting of monoalcohols, diols and triols.
Preferably, the antifreeze is chosen from the group consisting of methanol,
25 ethanol, ethylene glycol, isopropanol, n-propanol, propane-1,2-diol, propane-1,3-diol,
glycerol, butan-l-ol, butan-2-ol, butan-1,3-diol and butan-1,4-diol and mixtures
thereof, said mixtures comprising at least two of the antifreezes listed previously,
advantageously a mixture of ethanol and propane-1,2-diol.
Preferably, the antifreeze is chosen from the group consisting of methanol,
30 ethanol and propane-1,2-diol and mixtures thereof, particularly a mixture of ethanol
and propane-1,2-diol. Particularly preferably, the antifreeze is propane-1,2-diol.
The antifreeze is preferably present in the composition according to the
invention in a content of less than 40% by weight, preferably less than 25% by weight
and preferably less than 22% by weight relative to the total weight of the composition.
35 Such antifreeze contents allow the aqueous phase to remain in liquid form down to
temperatures below -20°C, preferably down to temperatures below -25°C.
14
Preferably, the composition according to the invention contains less than 10%
by weight of ethanol relative to the total weight of the composition.
Preferably, the composition according to the invention is free of ethanol.
Preferably, the composition according to the invention contains less than 10%
5 by weight of methanol relative to the total weight of the composition.
Preferably, the composition according to the invention is free of methanol.
Preferably, the composition according to the invention comprises less than
10% by weight of ethanol or methanol relative to the total weight of the composition.
If the composition according to the invention comprises both ethanol and methanol,
10 their total content by weight is less than 10% relative to the total weight of the
composition.
The composition according to the invention may also comprise one or more
emulsifiers.
Preferably, the emulsifier is a nonionic surfactant.
15 Preferably, the emulsifier is a nonionic surfactant, which may or may not be
oxyalkylenated, chosen from the group consisting of fatty alcohols, fatty acids,
sorbitans, plant or animal oils (which may or may not be hydrogenated); or mixtures
thereof.
The oxyalkylene units are more particularly oxyethylene units (i.e. ethylene
20 oxide groups), oxypropylene units (i.e. propylene oxide groups), or a combination
thereof, preferably oxyethylene units or a combination of oxyethylene units and
oxypropylene units.
In other words, the nonionic surfactant is preferably chosen from the group
consisting of fatty alcohols containing oxyethylene units and optionally oxypropylene
25 units, fatty acids containing oxyethylene units and optionally oxypropylene units, and
plant or animal oils, which are optionally hydrogenated, containing oxyethylene units
and optionally oxypropylene units.
The oxyethylene units (i.e. ethylene oxide groups) and oxypropylene units
(i.e. propylene oxide groups) may be randomly distributed or in block form.
30 The number of moles of ethylene oxide and/or propylene oxide preferably
ranges from 1 to 250, more particularly from 2 to 100, better still from 2 to 50 and
more particularly from 2 to 40.
Preferably, the number of moles of ethylene oxide ranges from 2 to 40.
For the purposes of the present invention, the term “fatty alcohol” means an
35 alcohol including at least 8 carbon atoms, preferably a C8-C40 alcohol, preferentially a
C8-C20 alcohol.
15
Among the fatty alcohols, mention may notably be made of 2-octyldodecanol,
decanol, lauryl alcohol, oleocetyl alcohol, isodecanol, oxoisotridecanol, cetostearyl
alcohol, capryl alcohol, myristyl alcohol, hexadecyl or palmityl alcohol, stearyl
alcohol, eicosanyl or arachidyl alcohol, behenyl alcohol, oleyl alcohol, eicosenyl or
5 gadoleyl alcohol, docosenyl alcohol, ricinoleyl alcohol, linoleyl alcohol and linolenyl
alcohol.
Preferably, the nonionic surfactant is chosen from the group consisting of
oxyalkylenated fatty alcohols preferably chosen from octyldodecanol, decanol, lauryl
alcohol, oleocetyl alcohol, isodecanol, capryl alcohol, oxoisotridecanol, cetostearyl
10 alcohol, eleostearyl alcohol, caprylyl alcohol, myristyl alcohol, hexadecyl or palmityl
alcohol, stearyl alcohol, eicosanyl or arachidyl alcohol, behenyl alcohol, oleyl alcohol,
eicosenyl or gadoleyl alcohol, docosenyl alcohol, ricinoleyl alcohol, linoleyl alcohol
or linolenyl alcohol, which are oxyalkylenated, preferably oxyethylenated and/or
oxypropylenated, and more preferentially oxyethylenated and optionally
15 oxypropylenated.
Preferably, the oxyalkylenated fatty alcohols are chosen from the group
consisting of oxyethylenated linoleyl alcohol, oxyethylenated linolenyl alcohol,
oxyethylenated eleostearyl alcohol and mixtures thereof.
The fatty alcohols mentioned previously may optionally be oxypropylenated
20 to a minor extent.
Preferably, the oxyalkylenated plant/animal oils (which may or may not be
hydrogenated) are in particular derivatives of ethoxylated mono-, di- and triglycerides
and comprise a complex mixture of ethoxylated glycerol optionally linked to one or
more fatty acid chains (which are themselves ethoxylated or not), fatty acids
25 ethoxylated on the acid function and/or on the hydroxyl function borne the fatty acid
chain, and also variable proportions of fatty acids, glycerol and fatty acid mono-, dior triglycerides.
For the purposes of the present invention, the term “fatty acid” means an acid
or a mixture of acids comprising at least 6 carbon atoms, preferably from 6 to 60 carbon
30 atoms, better still from 6 to 20 carbon atoms.
The oxyalkylenated plant/animal oils (which may or may not be
hydrogenated) are preferably chosen from the group consisting of optionally
hydrogenated, oxyethylenated (or ethoxylated) plant oils.
The optionally hydrogenated, oxyethylenated plant oils are preferably chosen
35 from the group consisting of ethoxylated castor oil and ethoxylated hydrogenated
castor oil comprising from 20 to 40 mol of ethylene oxide per mole of ricinoleic acid.
Mention may also be made of ethoxylated oils derived from coconut kernel oil, palm
16
oil, palm kernel oil, olive oil, groundnut oil, rapeseed oil, soybean oil, sunflower oil,
walnut oil, hazelnut oil, coconut oil, poppy oil, safflower oil, linseed oil, perilla oil,
oitica oil, and Chinese wood oil.
Mention may also be made of ethoxylated fats based on tallow oil, crude or
5 refined tall oil, whale oil, herring oil and sardine oil. All these ethoxylated glyceride
derivatives are characterized in that they include mixtures of ethoxylated mono-, di- or
triglycerides and also corresponding ethoxylated derivatives of fatty acids and of
glycerol. These fatty acids are notably saturated or unsaturated fatty acids derived from
caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic
10 acid, arachic acid, behenic acid, myristoleic acid, palmitoleic acid, oleic acid, ricinoleic
acid, erucic acid, linoleic acid, linolenic acid, oleostearic acid, licanic acid, gadoleic
acid, and erneic acid. Some unsaturated fatty acids may or may not be hydrogenated
as in the case of ethoxylated castor oil in which the ricinoleic group may or may not
have been partially or fully hydrogenated.
15 Preferably, the nonionic surfactant is chosen from the group consisting of
oxyalkylenated plant or animal oils (which may or may not be hydrogenated).
Preferentially, the nonionic surfactant is chosen from the group consisting of
plant oils, which are optionally hydrogenated, oxyethylenated and optionally
oxypropylenated.
20 More preferentially, the nonionic surfactant is chosen from the group
consisting of ethoxylated, optionally hydrogenated plant oils including from 20 to 40
mol of ethylene oxide, in particular ethoxylated castor oil and ethoxylated
hydrogenated castor oil including from 20 to 40 mol of ethylene oxide.
Even more preferentially, the nonionic surfactant is ethoxylated castor oil
25 including from 20 to 40 mol of ethylene oxide.
The emulsifier may be present in the composition according to the invention
in a content ranging from 0.1% to 10% by weight, preferably in a content ranging from
0.5% to 5% by weight, relative to the total weight of the composition.
Preferably, the emulsifier according to the invention does not comprise any
30 partially hydrolyzed polyvinyl acetate, more preferentially does not comprise any
polyvinyl acetate, more preferentially does not comprise any polyvinyl acetate or any
cellulose ester. This notably enables a reduction in the industrial preparation time, since
polyvinyl acetate which is in solid form requires a preliminary dissolution step, and
enables the risks associated with the handling of powders to be minimized.
35 The composition according to the invention may also comprise one or more
additives intended to give the final composition particular properties/characteristics.
17
These additives will ideally be present for the final polymerization or
copolymerization.
The additive may be chosen from the group consisting of antifoams, chaintransfer agents, chain extenders, pH regulators, plasticizers and mixtures thereof.
5 Preferably, the composition according to the invention comprises one or more
plasticizers, preferably chosen from the group consisting of phthalates, adipates,
benzoates and the hydrogenated derivatives of these molecules, including in particular
diisononylcyclohexane and diisononyl cyclohexanedicarboxylate and mixtures
thereof. Preferably, the composition according to the invention comprises:
10 - one or more organic peroxides of formula (I):
in which formula (I) R1
and R2
are identical and represent a linear or branched,
preferably branched, C1-C16, in particular C3-C12, even more preferentially C3-C10,
alkyl group;
15 - one or more organic peroxides of formula (II):
in which formula (II):
- R
3
represents a linear, branched or cyclic, preferably branched, C7-C20
20 alkyl group, preferably a C7-C16 alkyl group, in particular a C7-C10 alkyl
group, which may comprise, and is preferably interrupted with, one or
more oxygen atoms, preferably one oxygen atom;
- R
4
represents:
i) a linear or branched, preferably branched, C7-C20 alkyl group,
25 preferably a C7-C16 alkyl group, in particular a C7-C10 alkyl group,
which may comprise, and is preferably interrupted with one or more
oxygen atoms, preferably one oxygen atom;
18
ii) a linear or branched, preferably branched, C1-C7, preferably C2-C6,
alkyl group optionally substituted with one or more hydroxyl groups;
or
iii) a cyclic C7-C10, in particular cyclic C9, alkyl group.
5 - one or more emulsifiers, preferably chosen from the group consisting of
alkoxylated fatty alcohols, alkoxylated fatty acids and alkoxylated plant or animal oils
(which may or may not be hydrogenated) or mixtures thereof, preferably alkoxylated,
optionally hydrogenated, plant oils,
- optionally one or more antifreezes, preferably chosen from the group
10 consisting of ethanol, methanol and propane-1,2-diol.
Preferably, the composition according to the invention comprises:
- one or more organic peroxides of formula (I):
- in which formula (I) R1
and R2
15 are identical and represent a linear or
branched, preferably branched, C1-C16, in particular C3-C12, even more
preferentially C3-C10, alkyl group;
- one or more organic peroxides of formula (II),
20
in which formula (II):
- R
3
25 represents a linear or branched, preferably branched, C7-C20 alkyl
group, preferably a C7-C16 alkyl group, in particular a C7-C10 alkyl group;
- R
4
represents a linear or branched, preferably branched, C1-C7, preferably
C2-C6, alkyl group optionally substituted with one or more hydroxyl
groups;
19
- one or more emulsifiers chosen from the group consisting of nonionic
surfactants, preferably chosen from the group consisting of alkoxylated
fatty alcohols, alkoxylated fatty acids and alkoxylated plant or animal oils
(which may or may not be hydrogenated) or mixtures thereof;
5 - optionally one or more antifreezes preferably chosen from the group
consisting of ethanol, methanol and propane-1,2-diol.
Preparation of the composition
10 Preferably, the composition according to the invention may be prepared
according to a process successively comprising:
(i) the mixing:
(a) of at least one organic peroxide of formula (I):
in which formula (I) R1
and R2
15 , which may be identical or different,
represent a linear, branched or cyclic C1-C20 alkyl group which may
comprise one or more heteroatoms, preferably one or more oxygen
atoms; and
(b) of at least one organic peroxide of formula (II):
20
in which formula (II) R3
and R4
, which may be identical or different,
represent a linear, branched or cyclic C1-C20 alkyl group which may
comprise one or more heteroatoms, preferably one or more oxygen atoms,
25 and/or is optionally substituted with one or more hydroxyl groups;
(ii) optionally emulsifying the mixture.
Thus, the invention also relates to a process for preparing the composition
according to the invention comprising successively (i) mixing (a) at least one organic
20
peroxide of formula (I), as defined previously, and (b) at least one organic peroxide of
formula (II), as defined previously, (ii) emulsifying the mixture.
In other words, the process for preparing the composition may comprise
successively (i) at least one step of mixing (a) at least one organic peroxide of formula
5 (I), as defined previously, and (b) at least one organic peroxide of formula (II), as
defined previously, and (ii) optionally at least one step of emulsifying the mixture.
Preferably, the process according to the invention successively involves:
- adding at least one emulsifier, as defined previously, to water,
10
- mixing at least one organic peroxide of formula (I), as defined above, and
at least one peroxide of formula (II), as defined above, in aqueous phase,
- emulsifying said mixture.
15 The composition according to the invention may be prepared by dispersing at
least the emulsifier, and optionally one or more antifreezes and also one or more
additives, in water to obtain a homogeneous aqueous phase, and then by adding one or
more organic peroxides of formulae (I) and (II) to said aqueous phase, the whole being
then emulsified during an emulsion step at a temperature below 5°C (Celsius), so as to
20 limit the premature degradation of the peroxide and preferably below -5° Celsius.
The abovementioned steps may be performed in the particular order
prescribed, or in a different order.
The temperature at which the emulsion is prepared is not critical, but it must
be sufficiently low to avoid a high rate of decomposition of the organic peroxide, which
25 would result in a loss of titer. The temperature chosen depends on the organic peroxide.
Moreover, deionized water or distilled water is conventionally used to prepare the
aqueous emulsions. The preparation process includes a step of emulsifying with a highshear mixer to divide and/or homogenize the peroxide in the aqueous phase as much
as possible. Examples that may be mentioned include mechanically rotating blade and
30 anchor agitators, impeller agitators, i.e. one or more agitators mounted on a common
shaft, turbine agitators, i.e. those including baffles attached to the mixing vessel or
adjacent to the agitator members. Colloidal mills and homogenizers may also be used.
According to one embodiment feature, the process according to the invention
is characterized in that an ultrasonic mixer or a rotor-stator mixer is used. Following
35 the preparation of the emulsion, the steps of pumping and introducing the emulsions
into a polymerization reactor should be performed as quickly as possible. Accordingly,
the peroxide emulsions should have a low viscosity. Thus, the organic peroxide
21
emulsions according to the invention have a dynamic viscosity range, at -10°C and 100
s
-1
, of less than 850 mPa.s, preferably less than 700 mPa.s and preferentially less than
500 mPa.s just after production (the viscosity measurements are measured, for
example, according to the standard DIN 53019, which is well known to those skilled
5 in the art, with a machine such as a Haake VT550 Viscotester, at -10°C and for a shear
rate of 100 s-1
).
Their flowability or flow time measured by a consistometric cup technique is
less than 200 seconds, preferentially less than 100 seconds (DIN 53211, viscosity cup
diameter 4 mm, temperature 5°C). The subsequent polymerization or copolymerization
10 steps are, within the context of the present invention, no different from those of the
prior art.
Use
15 The present invention also relates to the use of an aqueous emulsion
composition comprising the mixture of organic peroxides, as defined above for the
polymerization or copolymerization of one or more ethylenically unsaturated
monomers, in particular of one or more vinyl monomers, preferably halogenated vinyl
monomers, and more preferentially vinyl chloride.
20 Mention may be made, as ethylenically unsaturated monomers, of acrylates,
vinyl esters, vinyl halide monomers, vinyl ethers, butadiene or vinylaromatic
compounds, such as styrene.
Preferably, the ethylenically unsaturated monomers are chosen from the group
consisting of vinyl halide monomers (i.e., halogenated vinyl monomers) and more
25 preferentially vinyl chloride.
Polymer
Another subject of the present invention relates to the halogenated vinyl
30 polymer obtained by polymerization of at least one ethylenically unsaturated
monomer, as defined previously, in the presence of the composition according to the
invention as defined above.
Preferably, the invention relates to the poly(vinyl chloride) obtained by
polymerization of vinyl chloride in the presence of the composition according to the
35 invention, in particular of the mixture of organic peroxides, as defined above.
In particular, the polymerization of the vinyl chloride monomer takes place in
suspension, at an initiation temperature ranging from 45°C to 70°C.
22
The examples that follow serve to illustrate the invention without, however,
being limiting in nature.
EXAMPLES
5
Example 1
The following compositions A1, A2, A3 and B1 are prepared according to the
procedure indicated below.
10 An emulsifier and an antifreeze are added to water.
The aqueous phase containing the emulsifier, namely the nonionic surfactant,
the antifreeze and water is stirred between 500 and 1000 revolutions per minute (rpm)
and kept at -5°C (Celsius) so as to obtain a homogeneous aqueous phase.
The organic peroxides are added gradually to the reactor containing this
15 water/surfactant/antifreeze mixture. Stirring is maintained for 3 minutes at 2000 rpm.
The whole is then stirred vigorously using a machine such as an Ultra-Turrax S-25N
18G ultrasonic machine for 2 minutes at 9500 rpm and then stirred using a paddle at
1000 rpm for 1 minute. Each emulsification is performed on 200 g in total.
20 Tests performed:
The dynamic viscosity measurements are taken using a viscometer such as a
Haake VT550 Viscotester machine. The measuring device is the SV-DIN 53019,
referring to the standard DIN 53019. The measurement is taken using coaxial cylinders
25 which create the shear. Between 5 and 10 ml (milliliters) of emulsion are introduced
into the measuring chamber maintained at -10°C. The values given in the examples
below correspond to a shear rate of 100 s-1
and are expressed in mPa.s. The accuracy
of the measurement is ±10% of the indicated value.
The flow time measurements are taken using consistometric cups according
30 to the standard DIN 53211 (viscosity cup diameter: 4 mm), which is well known to
those skilled in the art. The measurement is taken on 100 g of emulsion after
conditioning at +5°C. The flow time measurements are expressed in seconds and the
accuracy is ±10% of the indicated value.
The average droplet size and the maximum droplet size are determined via
35 conventional means using the light scattering technique over a period of from 1 to 6
months at a temperature of -25°C/-20°C.
23
The measurements are taken using a Malvern Mastersizer 2000® device at
room temperature. The average droplet size and the maximum droplet size are given
with an accuracy of ± 0.5 µm (micrometer).
5 Compositions:
The amounts of the ingredients below are indicated as weight percentages
relative to the total weight of the composition in Table 1 below:
10 [Table 1]
A1
(comp)
A2
(comp)
A3
(comp)
B1
(inv)
Di-sec-butyl
peroxydicarbonate
(Luperox® 225)
50% 50% 50% 50%
3-Hydroxy-1,1-
dimethylbutyl
peroxyneodecanoate
(Luperox® 610)
- - - 3%
Ethoxylated (31 EO)
castor oil
(Surfaline ® R31L)
1.44% - - -
Ethoxylated (20 EO)
castor oil
(Surfaline ® R20)
- 1.50% 1.50% 1.50%
Propane-1,2-diol 21.4% 21.4% 5.4% 21.4%
Ethanol - - 10%
Water qs 100 qs 100 qs 100 qs 100
Results:
At the time of production of the compositions
15
The average droplet size, maximum droplet size and viscosity cup results at
the time of production of compositions A1, A2, A3 and B1 are collated in Table 2
below:
24
[Table 2]
A1
(comp)
A2
(comp)
A3
(comp)
B1
(inv)
Average
droplet size (µm)
2.1 2.03 2.02 1.4
Maximum
droplet size (µm)
5 5.8 5 3.3
Viscosity cup
at T = +5°C (sec)
22 24 16 27
The results show that the composition according to the invention (composition
B) has an average droplet size (µm) and a maximum droplet size that are smaller than
5 the comparative compositions A1, A2 and A3 not comprising such a mixture of organic
peroxides.
Stability of the test compositions
10 The average and maximum droplet sizes of composition B determined at 6
months for the test compositions stored at -20°C in a freezer are 2.2 and 7.6 µm,
respectively.
Example 2:
15
Composition A4, corresponding to an aqueous emulsion of bis(2-ethylhexyl)
peroxydicarbonate (Luperox® 223), and composition A5 corresponding to an aqueous
emulsion of 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate (Luperox® 610), were
prepared according to a procedure similar to that described in Example 1.
20 Composition B2 was prepared by mixing 67% by weight of composition A4
and 33% by weight of composition A5 together.
Composition B3 was prepared by adding bis(2-ethylhexyl) peroxydicarbonate
and 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate in an aqueous phase in a weight
ratio of 67/33 according to the procedure described in Example 1.
25 Compositions A4, A5, B2 and B3 are described in Tables 3 to 5 below.

WE CLAIM:
1. An aqueous emulsion composition comprising:
- one or more organic peroxides of formula (I):
in which formula (I) R1
and R2
, which may be identical or different, represent a linear,
branched or cyclic C1-C20 alkyl group which may comprise, and is preferably interrupted with,
one or more heteroatoms, preferably one or more oxygen atoms;
- one or more organic peroxides of formula (II):
in which formula (II) R3
and R4
, which may be identical or different, represent a linear,
branched or cyclic C1-C20 alkyl group which may comprise, and is preferably interrupted with,
one or more heteroatoms, preferably one or more oxygen atoms, and/or is optionally substituted
with one or more hydroxyl groups;
the organic peroxide(s) of formula (I) and the organic peroxide(s) of formula (II) being
present in a concentration ranging from 40% to 70% by weight relative to the total weight of the
composition, preferably ranging from 40% to 65% by weight relative to the total weight of the
composition, more preferentially ranging from 40% to 60% by weight relative to the total weight
of the composition.
2. The composition as claimed in claim 1, characterized in that R1
and R2
, which may
be identical or different, represent a linear or branched C1-C16, more preferentially C3-C12, in
particular C3-C10, alkyl group which may comprise one or more heteroatoms, preferably one or
more oxygen atoms.
32
3. The composition as claimed in claim 1 or 2, characterized in that R1
and R2
are
identical and represent a linear or branched, preferably branched, C1-C16, more preferentially C3-
C12, in particular C3-C10, alkyl group.
4. The composition as claimed in any one of claims 1 to 3, characterized in that the
peroxides of formula (I) are chosen from the group consisting of bis(2-ethylhexyl)
peroxydicarbonate, di(sec-butyl) peroxydicarbonate, bis(1-methylheptyl) peroxydicarbonate,
di(n-propyl) peroxydicarbonate, bis(3-methoxybutyl) peroxydicarbonate, diethyl
peroxycarbonate and mixtures thereof, preferably bis(2-ethylhexyl) peroxydicarbonate and
di(sec-butyl) peroxydicarbonate.
5. The composition as claimed in any one of the preceding claims, characterized in
that:
- R
3
represents a linear, branched or cyclic, preferably branched, C7-C20 alkyl group,
preferably a C7-C16 alkyl group, in particular a C7-C10 alkyl group, which may
comprise, and is preferably interrupted with, one or more oxygen atoms, preferably
one oxygen atom;
- R4 represents:
i) a linear or branched, preferably branched, C7-C20, preferably C7-C16, in particular
C7-C10, alkyl group which may comprise, and is preferably interrupted with, one or
more oxygen atoms, preferably one oxygen atom;
ii) a linear or branched, preferably branched, C1-C7, preferably C2-C7, alkyl group
optionally substituted with one or more hydroxyl groups,
iii) a cyclic C7-C10, in particular cyclic C9, alkyl group.
6. The composition as claimed in any one of the preceding claims, characterized in that
the peroxides of formula (II) are chosen from the group consisting of α-cumyl
peroxyneodecanoate, α-cumyl peroxyneoheptanoate, 2,4,4-trimethylpent-2-yl
peroxyneodecanoate, tert-butyl peroxy(n-heptanoate), tert-butyl peroxyneodecanoate, α-cumyl
peroxy(n-heptanoate), tert-amyl peroxy(n-heptanoate), tert-butyl peroxyneoheptanoate, 2,5-
dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, tert-amyl peroxy(2-ethylhexanoate), tert-butyl
peroxy(2-ethylhexanoate), 1,1,3,3-tetramethylbutyl peroxy(2-ethylhexanoate),
hydroxyperoxyesters, tert-amyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl
peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxypivalate, tert-hexyl peroxyneodecanoate,
tert-hexyl peroxypivalate and mixtures thereof.
7. The composition as claimed in any one of the preceding claims, characterized in that
the peroxides of formula (II) are chosen from hydroxyperoxyesters chosen from the group
33
consisting of 4-hydroxy-2-methylpentyl peroxyneodecanoate, 4-hydroxy-2-methylpentyl
peroxyneoheptanoate, 4-hydroxy-2-methylpentyl peroxy(2-ethylhexanoate), 4-hydroxy-2-
methylpentyl peroxy(2-phenylbutyrate), 4-hydroxy-2-methylpentyl peroxy(2-
phenoxypropionate), 4-hydroxy-2-methylpentyl peroxy(2-butyloctanoate), 4-hydroxy-2-
methylpentyl peroxyneohexanoate, 4-hydroxy-2-methylpentyl peroxyneotridecanoate, 4-
hydroxy-2-methylhexyl peroxyneohexanoate, 4-hydroxy-2-methylhexyl peroxyneodecanoate, 5-
hydroxy-1,3,3-trimethylcyclohexyl peroxyneodecanoate, 4-hydroxy-2,6-dimethyl-2,6-
di(neohexanoylperoxy)heptane, 4-hydroxy-2,6-dimethyl-2,6-di(neodecanoylperoxy)heptane, 3-
hydroxy-1,1-dimethylbutyl peroxy(2-ethylhexanoate), 3-hydroxy-1,1-dimethylbutyl
peroxyneodecanoate, 3-hydroxy-1,1-dimethylbutyl peroxyneoheptanoate and mixtures thereof,
preferably 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate.
8. The composition as claimed in any one of the preceding claims, characterized in that
the weight ratio of organic peroxide(s) of formula (I)/peroxide(s) of formula (II) ranges from 99/1,
in particular from 97/3, in particular from 90/10 and preferentially from 80/20 to 50/50.
9. The composition as claimed in any one of the preceding claims, characterized in that
it also comprises one or more antifreezes.
10. The composition as claimed in any one of the preceding claims, characterized in that
it comprises ethanol or methanol in a content of less than 10% by weight.
11. The composition as claimed in any one of the preceding claims, characterized in that
it comprises one or more emulsifiers.
12. The composition as claimed in any one of the preceding claims, characterized in that
it comprises an average organic peroxide droplet size of less than 10 µm, preferably less than 5
µm and a maximum droplet size of less than 20 µm, preferably less than 15 µm.
13. A process for preparing a composition as defined in any one of claims 1 to 12,
characterized in that it successively involves:
(i) mixing:
(a) at least one organic peroxide of formula (I) as defined according to any one of
Claims 1 to 4,
(b) at least one organic peroxide of formula (II) as defined according to any one of
Claims 1 and 5 to 7,
(ii) optionally emulsifying the mixture.
34
14. The use of the composition as defined in any one of claims 1 to 12, for the
polymerization or copolymerization of one or more ethylenically unsaturated monomers,
preferably one or more halogenated vinyl monomers, and more preferentially vinyl chloride.
15. A halogenated vinyl polymer obtained by polymerization of at least one
ethylenically unsaturated monomer in the presence of the composition as defined in any one of
claims 1 to 12.