Field of the invention
5
A subject matter of the invention is an aqueous organic peroxide
composition, liquid at storage temperature, which can be used in the
polymerization -or the cnpnlymerization of ethylenically unsaturated monomers
and in particular of vinyl chloride. The invention relates more particularly to an
10 aqueous organic peroxide composition comprising a nonionic surfactant.
The precautions inherent in the instability of organic peroxides form an
integral part of the knowledge well known to a person skilled in the art.
Furthermore, it is for its unstable properties that organic peroxides are used, inter
alia, as initiator of the polymerization of vinyl monomers.
15 The most reactive organic peroxides are commonly packaged in the form of
an aqueous emulsion in the presence of antifreezes. This packaging makes it
possible both to absorb and to dissipate the energy generated in the event of
possible decompositions of the peroxides and to maintain the emulsion in a liquid
form, at temperatures of less than -10°C, generally of less than -20°C. This
20 packaging thus limits possible unintentional decomposition of the peroxides.
An emulsion comprises, in addition to water and antifreeze, an emulsifier
which makes it possible to lower the interfacial tension between the aqueous
phase and the peroxide in order to facilitate the dispersion thereof in the form of
droplets and to stabilize these droplets over time (maintenance of the sizes).
25 Emulsions of organic peroxides are thus stabilized not only during their
production but in particular during a relatively lengthy period corresponding to
the transportation and storage before final use as polymerization initiator.
Although these precautions are generally sufficient to keep the handling of
organic peroxides safe, they are generally insufficient to meet all the expectations
30 of the users in terms of stability of the mean droplet size over time but also in
terms of viscosity of the emulsion.
Over time, the emulsion destabilizes and the mean peroxide droplet size
increases. The increase in the size of the droplets can result in a phase separation.
WO 2014/044961 PCT7FR2013/052129
According to the minimum technical criteria, a peroxide emulsion is regarded as
satisfactory if the mean droplet size does not exceed 20 um. A mean droplet size
of less than 10 urn, more advantageously of less than 5 \im, is generally required,
as well as a maximum size not exceeding 20 um.
b Use of a nonhomogeneous organic peroxide emulsion as polymerization
initiator in a vinyl monomer emulsion or suspension can produce a
nonhomogeneity in the final product. This nonhomogeneity is generally
characterized by polymer particles poorly gelled during implementation in the
molten state (fish eyes). In point of fact, the presence of fish eyes opacifies the
10 polymer material. These stability considerations are thus very important for the
applications where the transparency of the final product is imperative, in
particular for medical applications.
Thus, the droplets of peroxide (by agglomeration of the peroxide or
peroxides present in the emulsion, in particular after a certain period of time) of an
15 organic peroxide emulsion have to have a low mean size, have a narrow
distribution and be stable over time.
The stages of discharging the emulsion into intermediate storage silos, of
pumping and of introduction of a peroxide emulsion into a polymerization reactor
are important stages for the quality of the polymer obtained and the reliability of
20 the polymerization process. These handling stages have to be carried out as
rapidly as possible. In order to do this, it is crucial for the peroxide emulsion to
exhibit a low viscosity, so that the flow of the emulsion is rendered as easy as
possible. At a given temperature, the viscosity of this type of emulsion varies in
particular as a function of the shear rate. It decreases when the shear rate increases
25 and stabilizes for rate values generally of greater than 100 s"1. Thus, an organic
peroxide emulsion must have a maximum dynamic viscosity of 1000 mPa.s
(milliPascal.second) at low temperature, typically of the order of -10°C, for a
shear rate of 100 s"1 (the dynamic viscosity measurements are carried out using
coaxial cylinders which create the shearing, for example according to the standard
30 DIN 53019).
In point of fact, a person skilled in the art knows that, for this type of
emulsion, to attempt to reduce the size of the droplets contributes to increasing the
viscosity (see section 1.4 of the article by JP Canselier and M.Poux, "Procedes
WO 2014/044961 PCT/FR2013/052129
d'emulsification - Mecanisme de formation des emulsions [Emulsification
processes - Mechanism of Formation of Emulsions]", Techniques de lTngenieur,
J2 152, pp 1-12, publication of June 10, 2004).
Thus, to achieve these two main objectives simultaneously is a major
5 difficulty for a person skilled in the art due to the conflicting choices which he is
obliged to envisage.
State^ofLthe a rt
The document WO 99/05101 discloses the use of partially hydrolyzed
10 polyvinyl acetate (PVA) as protective colloid in combination with nonionic
surfactants having an HLB (hydrophilic-lipophilic balance) value of greater than
16, for aqueous peroxyester emulsions. A peroxide emulsion necessitates a low
viscosity. Thus, this document specifies that a surfactant with an HLB of less than
16 can increase the final viscosity of the emulsion.
15 In the same way, the document WO 03/095500 discloses the use of partially
hydrolyzed PVA in combination with nonionic surfactants having an HLB
(hydrophilic-lipophilic balance) value of greater than 15, for aqueous
peroxydicarbonate or diacyl peroxide emulsions. This document also specifies
that the addition of surfactants with an HLB of less than 10 has a harmful effect
20 and increases the final viscosity of the organic peroxide emulsion.
The document US 3 988 261 lists a broad range of surfactants, both anionic
or cationic and nonionic, but does not disclose the use of polyvinyl acetate as
protective colloid for the stabilization of organic peroxide emulsion.
There currently does not exist any document of the state of the art which
25 discloses exclusively the use of nonionic emulsifiers other than partially
hydrolyzed polyvinyl acetate or cellulose derivatives for the stabilization of
organic peroxide emulsion. Thus, the choice of the surfactant is essential for the
final properties of the emulsion, and was obtained until now by the use of a
protective colloid agent (partially hydrolyzed polyvinyl acetate or cellulose
30 derivatives) used alone or in combination with nonionic surfactants other than
partially hydrolyzed polyvinyl acetate (PVA).
A PVA is packaged in the fine powder form. In an industrial process, the
products are advantageously introduced in the liquid form. A dissolution stage for
WO 2014/044961 ^— PCT/FR2013/052129
the preparation of an aqueous PVA solution is thus necessary. This preparation
stage represents an additional stage. The dissolution of PVA is difficult and
requires a relatively lengthy preparation time, which thus exhibits a major
additional cost. The dissolution of PVA in water can also form gels. These
5 undissolved gels have to be removed by the presence of one or more filters before
the introduction into a peroxide composition. The dissolution capability of these
surfactants depends on their degrees of hydrolysis. More particularly, at an equal
concentration, it. is more difficult to homogenize an aqueous solution of a PVA
having a high degree of hydrolysis and to introduce this solution into a reactor
10 than a solution comprising a PVA having a lower degree of hydrolysis.
Furthermore, the handling of powder on the industrial scale can represent,
for an operator, additional precautions in terms of health and safety with regard to
the risks of these powders (presence of fine particles, risks related to dust, and the
like).
15 Ideally, a surfactant, such as PVA, should be, at ambient temperature, in the
liquid form or in the paste form, in order to facilitate the dissolution thereof in an
aqueous solution or the direct introduction thereof into an industrial process.
Thus, from the viewpoint of its many disadvantages, it is desirable to
replace polyvinyl acetate (PVA) as emulsifying agent of an aqueous organic
20 peroxide composition.
Brief description of the invention
The applicant company has discovered that the use of a nonionic emulsifier
according to the invention devoid of protective colloid surprisingly stabilizes an
25 aqueous organic peroxide emulsion and meets the conditions required regarding
the droplet size, the viscosity and the flow time of the emulsion. The applicant
company has also discovered that the addition of an emulsifier according to the
invention makes it possible to obtain an organic peroxide emulsion which is less
viscous than that commonly obtained with a PVA protective colloid or a mixture
30 of this PVA protective colloid in combination with other nonionic emulsifiers.
The present invention thus relates to an aqueous organic peroxide emulsion
composition devoid of protective colloid agent, consisting of:
- from 10% to 65% by weight of one or more organic peroxides,
WO 2014/044961 - PCT/FR2013/052129
- from 2% to 25% by weight of at least one antifreeze agent,
- from 0.01% to 10% by weight of an emulsifying agent,
- optionally at least one additive,
- water, the amount of which is determined so as to form the remainder of
5 the composition (up to 100%),
characterized in that the emulsifying agent consists of a nonionic surfactant
chosen exclusively from:
- a hlock copolymer comprising at. least, one alkylene oxide hlock; or
- a block copolymer comprising at least two alkylene oxide blocks; or
10 - an alkoxylated fatty alcohol; or
- an alkoxylated fatty acid; or
- an alkoxylated (hydrogenated or nonhydrogenated) vegetable or animal
oil; or
- a mixture of several of these components.
15 The invention exhibits the following advantages and thus makes it possible
to obtain:
- an emulsion exhibiting a low mean droplet size with a homogeneous and
monomodal size distribution, without the appearance of gel;
- an emulsion comprising a mean droplet size (d5o) of less than 10 um after
20 production or during storage at -20°C for at least four months, the mean size being
stabilized for at least four months. The maximum droplet size (dioo) does not
exceed 20 um;
- an emulsion compatible with the polymerization of ethylenically
unsaturated derivatives and in particular vinyl monomers, such as the vinyl
25 chloride monomer, a liquid emulsion having a very low viscosity allowing a very
short flow time;
- an emulsion having a preparation time at the industrial level which is
advantageously reduced, in particular by virtue of the absence of preparation of
the solution in water of protective colloid of partially hydrolyzed PVA type;
30 - an emulsion which minimizes the risks related to the handling of powders
(health and safety of the operators).
Other characteristics of the invention are presented below:
WO 2014/044961 _- PCT7FR2013/052129
- preferably, the alkoxylated vegetable or animal oil is chosen from
ethoxylated derivatives of mono-, di- or triglycerides and their mixtures;
- advantageously, the alkoxylated vegetable or animal oil comprises a
mixture of ethoxylated glycerol connected or not connected to one or more chains
of fatty acids, the latter being or not being ethoxylated, fatty acids ethoxylated on
the acid functional group and/or on the hydroxyl functional group carried by the
fatty acid chain, and also variable proportions of fatty acids, of glycerol and of
mono-, di- or triglycerides;
- preferably, the fatty alcohol comprises an aromatic or nonaromatic,
saturated or unsaturated, cyclic or noncyclic and linear or branched chain of 4 to
60 and preferably 4 to 20 carbon atoms and between 3 and 80 alkylene oxide
units, preferably between 20 and 40;
- preferably, the alkoxylated fatty acid comprises an aromatic or
nonaromatic, saturated or unsaturated, cyclic or noncyclic and linear or branched
chain of 4 to 60 and preferably 4 to 20 carbon atoms and between 3 and 80
alkylene oxide units, preferably between 20 and 40;
- according to a possibility offered by the invention, the vegetable oil is
ethoxylated or ethoxylated hydrogenated, such as, in particular, an ethoxylated
castor oil or ethoxylated hydrogenated castor oil;
- advantageously, the block copolymer comprises at least two alkylene
oxide blocks, said alkylene oxide block comprising between 5 and 80 units;
furthermore, the alkylene oxide units are preferably ethylene oxide units alone or
ethylene oxide and propylene oxide and/or butylene oxide units;
- advantageously, the nonionic surfactant is present at a concentration of
between 0.05% and 5% by weight in the emulsion, preferably between 0.1% and
3%o by weight;
- preferably, the composition according to the invention comprises more
than 30%o by weight of one or more organic peroxides, preferably more than 45%
by weight;
- advantageously, the organic peroxide or peroxides are chosen from
peroxyesters, peroxydicarbonates and/or. diacyl peroxides.
It should be noted that some components, such as block copolymers,
forming the subject matter of the present invention are sometimes provided,
WO 2014/044961 PCT7FR2013/052129
according to their molar masses, in the powder form. Preferably, in order to
overcome the problems of health and safety of the operators mentioned above,
these components will ideally be provided in the liquid form or in the paste form.
The present invention also relates to a process for the preparation of the
5 composition according to the invention described above, characterized in LhaL il
comprises the stages, optionally successive, of:
- dispersion of the antifreeze agent, optionally at least said additive and also
the emulsifying agent in water in order to obtain a homogeneous aqueous phase,
then
10 - the peroxide is added to the aqueous phase, and
- the mixture thus formed is emulsified during an emulsion stage at a
temperature of less than 5°C.
Finally, the invention relates to the use of the composition described above
in the polymerization or copolymerization of ethylenically unsaturated monomers.
15 Preferably, the ethylenically unsaturated monomers comprise vinyl chloride.
The description which will follow is given solely by way of illustration and
without implied limitation.
Detailed description of the invention
20 The invention relates to organic peroxide emulsions concentrated in
emulsion, said organic peroxide being present at a concentration of 10% to 65%,
preferably of greater than 30% and more preferably of greater than 45%, by
weight of the emulsion and is chosen from peroxyesters, peroxydicarbonates and
diacyl peroxides.
25 Among the peroxyesters, the preferred peroxides are a-cumyl
peroxyneodecanoate, a-cumyl peroxyneoheptanoate, 2,4,4-trimethylpent-2-yl
peroxyneodecanoate, 3-hydroxy-l,l-dimethylbutyl peroxyneodecanoate, 3-
hydroxy-l,l-dimethylbutyl peroxyneoheptanoate, tert-amyl peroxypivalate, tertbutyl
peroxypivalate, tert-butyl peroxyneoheptanoate, 2,5-dimethyl-2,5-di(2-
30 ethylhexanoylperoxy)hexane, tert-amyl peroxy-2-ethylhexanoate, tert-butyl
peroxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, 3-
hydroxy-l,l-dimethylbutyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate
and their mixtures.
WO 2014/044961 PCT7FR2013/052129
Among the peroxydicarbonates, the preferred peroxides are di(sec-butyl)
peroxydicarbonate, dibutyl peroxydicarbonate, diisopropyl peroxydicarbonate,
di(2-ethylhexyl) peroxydicarbonate, bis(3-methoxybutyl) peroxydicarbonate,
bis(isobutyl) peroxydicarbonate, dineopentyl peroxydicarbonate, bis(l-
5 methylheptyl) peroxydicarbonate, bis[2-(2-methoxyethoxy)ethyl]
peroxydicarbonate, bis(3-methoxy-3-methylbutyl) peroxydicarbonate, bis(2-
ethoxyethyl) peroxydicarbonate and their mixtures.
Among the diacyl peroxides, the preferred peroxides are diisobutyroyl
peroxide, di(3,5,5-trimethylhexanoyl) peroxide, di(2-ethylhexanoyl) peroxide,
10 di(2-ethylbutanoyl) peroxide, and also asymmetric peroxides, such as isobutyroyl
octanoyl peroxide, isobutyroyl decanoyl peroxide, isobutyroyl lauroyl peroxide,
2-ethylbutanoyl decanoyl peroxide, 2-ethylhexanoyl lauroyl peroxide and their
mixtures.
In order to be able to be stored at temperatures of less than -10°C, preferably
15 of less than -20°C, the composition according to the invention comprises an
antifreeze and more particularly a mixture of antifreezes.
As regards the antifreeze agent, mention may be made, for example, of
monoalcohols, diols and triols, such as methanol, ethanol, ethylene glycol,
isopropanol, n-propanol, propane- 1,2-diol, propane-l,3-diol, glycerol, butan-1-ol,
20 butan-2-ol, butane-l,3-diol and butane-1,4-diol and their mixtures, these mixtures
comprising at least two of the antifreeze agents listed above, one of light alcohol
type and the other of heavy alcohol type, advantageously a mixture of methanol
and propane-1,2-diol.
The emulsifier according to the invention does not comprise a protective
25 colloid and consists of a nonionic surfactant chosen from a block copolymer
comprising at least one alkylene oxide block; or a block copolymer comprising at
least two alkylene oxide blocks; or an alkoxylated fatty alcohol; or an alkoxylated
fatty acid; or an alkoxylated (hydrogenated or nonhydrogenated) vegetable or
animal oil; or a mixture of several of these components.
30 According to one embodiment, the emulsifier according to the invention can
consist of a block copolymer comprising at least one alkylene oxide block (chosen
from diblock or triblock copolymers) or a block copolymer comprising at least
two alkylene oxide blocks (chosen from triblock copolymers). The block
WO 2014/044961 .» PCT/FR2013/052129
consisting of alkylene oxide polymer is chosen from, ethylene oxide, propylene
oxide or butylene oxide. A diblock copolymer according to the invention is a
copolymer exhibiting an alkylene oxide block, more particularly an ethylene
oxide block, and a block having hydrophobic properties commonly known to a
5 person skilled in the art; for example a polyethylene or polypropylene block can
be used. The triblock copolymer according to the invention comprising at least
one alkylene oxide block is either chosen from a copolymer consisting of two
alkylene oxide blocks surrounding a block of hydrophobic polymer commonly
known to a person skilled in the art or is a block of alkylene oxide polymer
10 surrounded by two blocks of hydrophobic polymer commonly known to a person
skilled in the art. The alkylene oxide block is predominantly an ethylene oxide
block. The triblock copolymer according to the invention comprising at least two
alkylene oxide blocks is chosen with a first block consisting predominantly of
ethylene oxide and to a minor extent of propylene oxide polymerized
15 simultaneously or exclusively of polymerized ethylene oxide, and a second block
consisting predominantly of propylene oxide and to a minor extent of butylene
oxide polymerized simultaneously or exclusively of polymerized propylene oxide.
The third block has the same structure as the first or second block described above
but is covalently bonded only to the block having a different composition.
20 According to another embodiment, the emulsifier according to the invention
can consist of an alkoxylated fatty alcohol, characterized in that it more
particularly comprises ethylene oxide, propylene oxide or butylene oxide groups,
and in particular a fatty alcohol comprising ethylene oxide chemical groups
polymerized on the fatty alcohol and comprising or not comprising propylene
25 oxide and/or butylene oxide groups polymerized on the fatty alcohol, the different
oxide groups being distributed randomly or blockwise. Mention will in particular
be made, among the fatty alcohols which can be used, of octyldodecanol, decanol,
lauryl alcohol, oleocetyl alcohol, isodecanol, capric alcohol, the oxo alcohol
isotridecanol, cetearyl alcohol, caprylic alcohol, myristyl alcohol, hexadecanol or
30 palmityl alcohol, stearyl alcohol, eicosanyl or arachidyl alcohol, behenyl alcohol,
oleyl alcohol, eicosenyl or gadolyl alcohol, docosenyl alcohol, ricinoleyl alcohol,
linoleyl alcohol, linolenyl alcohol, and the like.
WO 2014/044961 ,, PCT/FR2013/052129
According to a preferred embodiment, the emulsifier according to the
invention is an alkoxylated fatty acid or an alkoxylated (hydrogenated or
nonhydrogenated) vegetable/animal oil. The alkoxylated fatty acids are
characterized in that they more particularly comprise ethylene oxide, propylene
5 oxide or butylene oxide groups. These tatty acids in particular comprise ethylene
oxide chemical groups polymerized on the fatty acid and/or on a hydroxyl
functional group present on the fatty chain of the acid and comprising or not
comprising propylene oxide and/or butylene oxide groups polymerized on the
fatty acid and/or on a hydroxyl functional group present on the fatty chain of the
10 acid, the different oxide groups being distributed randomly or blockwise. The
alkoxylated (hydrogenated or nonhydrogenated) vegetable/animal oils are in
particular ethoxylated derivatives of mono-, di- and triglycerides and comprise a
complex mixture of ethoxylated glycerol connected or not connected to one or
more fatty acid chains (themselves ethoxylated or nonethoxylated), of fatty acids
15 ethoxylated on the acid functional group and/or on the hydroxyl functional group
carried by the fatty acid chain, and also variable proportions of fatty acids, of
glycerol and of mono-, di- or triglycerides of fatty acids. The fatty acid has a
single chemical structure or can be a mixture of chemical structures according to
the nature of the oil used before ethoxylation or the mixture of oils used before the
20 ethoxylation. The alkoxylation of the oil is carried out predominantly with
ethylene oxide but polymerized blocks of propylene oxide and/or butylene oxide
can also be inserted randomly or blockwise. The fatty acids bonded to the glycerol
or fatty acids used in the alkoxylated fatty acids have chain lengths between 4 and
60 carbon atoms and preferably 4 to 20 and the number of moles of ethylene
25 oxide is between 3 and 80 per mole of acid, more particularly of between 20 and
40. More specifically, particular interest is paid to ethoxylated vegetable oils, such
as ethoxylated castor oil and ethoxylated hydrogenated castor oil of 20 to 40 mol
of ethylene oxide per mole of ricinoleic acid. Mention may also be made of
ethoxylated oils derived from copra, palm, palm kernel, olive, peanut, rapeseed,
30 soybean, sunflower, walnut, hazelnut, coconut, poppy seed, safflower, linseed,
perilla, oiticica and China wood oils.
Mention may also be made of ethoxylated fats based on tallow, crude or
refined tall, whale, herring and sardine oils. All of these ethoxylated glyceride
WO 2014/044961 ,, PCT/FR2013/052129
derivatives are characterized in that they comprise mixtures of ethoxylated mono-,
di- or triglycerides and also ethoxylated derivatives of the corresponding fatty
acids and glycerol. These fatty acids result in particular from saturated or
unsaturated fatty acids caproic, caprylic, capric, lauric, myristic, palmitic, stearic,
5 arachidic, behenic, myristolelc, palmitoleic, oleic, ricinolcic, erucic, linolcic,
linolenic, oleostearic, licanic, gadoleic, erneic and resin acids.
Some unsaturated fatty acids are or are not hydrogenated, as in the case of
ethoxylated castor oil where the ricinoleic group has or has not been partially or
completely hydrogenated.
10 It is not departing from the scope of the invention to use a mixture of
emulsifiers according to the invention.
The emulsion according to the invention can also comprise one or more
additives intended to provide the final thermoplastic composition with specific
properties/characteristics. These additives will ideally be present for the final
15 polymerization or copolymerization.
These additives are under no circumstances a partially hydrolyzed polyvinyl
acetate.
Thus, as regards the additive, it can be chosen from antioxidants; UV
protecting agents; processing aids, having the role of improving the final
20 appearance during the processing thereof, such as fatty amides, stearic acid and its
salts, ethylenebisstearamide or fluoropolymers; antifogging agents; antiblocking
agents, such as silica or talc; fillers, such as calcium carbonate, and nanofillers,
such as, for example, clays; coupling agents, such as silanes; crosslinking agents,
such as peroxides; antistatic agents; nucleating agents; pigments; dyes;
25 plasticizers; viscosity reducers and flame-retardant additives, such as aluminum or
magnesium hydroxides.
The aqueous liquid organic peroxide emulsion of the present invention can
optionally comprise additives including pH-adjusting agents, such as phosphate
and citrate buffers, chelating agents, biocides, for example fungicides,
30 antiozonants, antioxidants, degradation inhibitors, blowing agents and moldrelease
agents.
The aqueous liquid organic peroxide emulsion of the present invention can
also comprise additives generally used to stabilize the organic peroxide or to slow
'^^^BBEgag^EgJ^m^^&&^m^ir_— ----- ------ - - - ^ -_- , -^
WO 2014/044961 PCT/FR2013/052129
down its decomposition, such as phlegmatizers (isododecane, mineral oil, and the
like) or hydroperoxides.
These additives can be added in amounts generally used and known to a
person skilled in the art. These additives are generally used in contents of between
5 10 ppm and lOOOOppm by weight, with respect to the weight of final
polyethylene or ethylene copolymer or of final polyvinyl chloride. The
plasticizers, viscosity reducers and flame-retardant additives can reach amounts
much greater than 10 000 ppm.
The invention also relates to a process for the preparation of the emulsion
10 described above, characterized in that the antifreeze agent, optionally one or more
additives and also at least one emulsifier are dispersed in water, in order to obtain
a homogeneous aqueous phase, and then the peroxide is added to said aqueous
phase, everything being subsequently emulsified during an emulsion stage at a
temperature of less than 5°C (Celsius), so as to limit the premature decomposition
15 of the peroxide, and preferably of less than -5°Celsius.
The stages mentioned above can be executed in the specific order prescribed
or in a different order.
Apart from the specific successive stages of the process for the preparation
of the composition according to the invention, the preparation of the emulsion
20 does not differ in any way from the techniques and devices well known to a
person skilled in the art. The temperature at which the emulsion is prepared is not
critical but it must be sufficiently low to prevent a significant degree of
decomposition, the result of which would be a fall in the assay. The temperature
chosen depends on the organic peroxide. Furthermore, in order to prepare the
25 aqueous emulsions, deionized water or distilled water is conventionally used.
The preparation process comprises an emulsion stage with a mixer having a
high shear rate in order to divide and/or homogenize the peroxide in the aqueous
phase as best as possible. Mention may be made, by way of example, of
mechanically rotating paddle and anchor stirrers, propeller stirrers, that is to say
30 one or more stirrers fitted to a common shaft, or turbine stirrers, that is to say
those comprising baffles attached to the mixing vessel or in a position adjacent to
the stirring members. Colloid mills and homogenizers can also be used.
According to one implementational characteristic, the process according to the
WO 2014/044961 PCT7FR2013/052129
invention is characterized in that an ultrasonic mixer or a rotor/stator mixer is
used.
Subsequent to the preparation of the emulsion, the stages of pumping and of
introducing the emulsions into a polymerization reactor have to be carried out as
5 rapidly as possible. For this reason, the peroxide emulsions should have a low
viscosity.
Thus, the organic peroxide emulsions according to the invention exhibit a
dynamic viscosity range at -ICC. 100 s"1. of less than 1000 mPa.s. preferably of
less than 700 mPa.s, immediately after production (the viscosity measurements
10 are measured, for example, according to the standard DIN 53019, well known to a
person skilled in the art, with a device of Viscotester Haake VT550 type, at -10°C
and for a shear rate of 100 s"1).
Their flowability or flow time, measured by a flow cup technique, is less
than 200 seconds, preferably less than 100 seconds (DIN 53211, diameter of the
15 viscosity cup 4 mm, temperature of 5°C).
The subsequent polymerization or copolymerization stages are not, in the
context of the present invention, different from those of the prior art. The
polymerization of the vinyl chloride monomer is carried out in suspension at an
initiation temperature of between 45 and 70°C.
20 The invention also relates to the use of the emulsion defined above in the
polymerization or copolymerization of ethylenically unsaturated monomers. A
homopolymer is obtained by polymerization when just one ethylenically
unsaturated monomer is polymerized. A copolymer is obtained by polymerization
when at least two ethylenically unsaturated monomers are polymerized. It is
25 understood that the monomers are capable of polymerizing with one another.
Mention may be made, as ethylenically unsaturated monomer, of acrylates,
vinyl esters, vinyl halide monomer, vinyl ethers, vinylaromatic compounds, such
as styrene, butadiene and preferably vinyl chloride.
The organic peroxide emulsion according to the present invention can be
30 used in applications such as the polymerization of acrylic monomers, reactions for
the modification of polymers, crosslinking reactions, bulk polymerization
reactions and curing processes, as used in unsaturated polyester resins.
WO 2014/044961 ^- PCT/FR2013/052129
Production of the formulations of the compositions tested:
The emulsions comprising a surfactant according to the invention and that
comprising a comparative PVA are prepared according to the same procedure.
The aqueous phase comprising the surfactant, the antifreeze agent and the
5 water is stirred at between 500 and 1000 rpm (revolutions per minute) and
maintained at -5°C (Celsius). The organic peroxide is gradually added to the
reactor containing this water/surfactant/antifreeze mixture. Stirring is maintained
at 7.000 rpm for three minutes. The combined mixture is subsequently vigorously
stirred using an "Ultra-Turrax type S-25N 18G" ultrasonic device at 9500 rpm for
10 two minutes, followed by stirring using a paddle at 1000 rpm for one minute.
Each emulsion is carried out on 200 grams in total.
Tests carried out:
The dynamic viscosity measurements are carried out using a viscometer of
15 "Viscotester Haake VT550" type. The measurement device is the "SV-DIN
53019", referring to the standard DIN 53019. The measurement is carried out
using coaxial cylinders which create the shearing. Between 5 and 10 ml
(milliliters) of emulsion are introduced into the measurement chamber maintained
at -10°C. The values given in the examples below correspond to a shear rate of
20 100 s"1 and are expressed in mPa.s. The accuracy of the measurement is ±10% of
the value shown.
The measurements of flow time are carried out using flow cups according to
the standard DIN 53211 (diameter of the viscosity cup: 4 mm), which is well
known to a person skilled in the art. The measuring is carried out on 100 g of
25 emulsion after conditioning at +5°C. The measurements of flow time are
expressed in seconds and the accuracy is ±10% of the value shown.
The droplet size (dioo and d50) is determined by conventional means using
the light scattering technique. The term "dioo" corresponds to the diameter such
that 100% of the volume of the sample of organic peroxide droplets in the
30 aqueous emulsion has a diameter of less than dioo and the term "d50" corresponds
to the average diameter such that 50% of the volume of the organic peroxide
droplets in the aqueous emulsion has a diameter of less than dso. The
measurements are carried out using a Malvern Master Sizer 2000® device at
WO 2014/044961 a PCT/FR2013/052129
ambient temperature. The droplet size dso or dioo is given with an accuracy of
± 0.5 urn (micrometer).
Starting materials of the compositions tested:
5 Mainly two emulsions were prepared In order to carry out the tests which
make it possible to characterize the compositions, according to the prior art and
according to the invention.
The first emulsion consists of di(2-ethylhexyl) peroxydicarbonate at 60%
by weight comprises:
10 - an antifreeze system which is a mixture of alcohols with a 20/80 ratio by weight
of propylene glycol/methanol, with an overall concentration of 14%;
- a water/antifreeze ratio of 64/36 by weight;
- a content of di(2-ethylhexyl) peroxydicarbonate of 60% by weight. The di(2-
ethylhexyl) peroxydicarbonate is Luperox® 223 from Arkema, with a purity of
15 97%;
- a content of surfactant of 1.2% by weight;
- the remainder is distilled water.
The second emulsion consists of tert-butyl peroxyneodecanoate at 50% by
weight comprises:
20 - an antifreeze system which is a mixture of alcohols with a 40/60 ratio by weight
of propylene glycol/methanol, with an overall concentration of 16%;
- a water/antifreeze ratio of 67/33 by weight;
- a content of tert-butyl peroxyneodecanoate of 50% by weight. The tert-butyl
peroxyneodecanoate is Luperox® 10 from Arkema, with a purity of 97%;
25 - a content of surfactant of 1.2% by weight;
- the remainder is distilled water.
Characterizations of the surfactants:
The characteristics of the emulsifying agent according to the invention and a
30 comparative protective colloid of partially hydrolyzed polyvinyl acetate (PVA)
type are presented in table 1 below.
The emulsifying agents la, lb, lc and Id are characterized here by the
determination of the hydrophilic-lipophilic balance (HLB), which makes it
WO 2014/044961 .^ PCT/FR2013/052129
possible to assess the solubility of any surface-active agent, and by the ethylene
oxide number. The HLB measurement (from 1 to 40) and its meaning (the higher
the HLB, the more hydrophilic the emulsifier) are well known to a person skilled
in the art. The PVA is characterized by its degree of polymerization and by its
degree of hydrolysis.
TABLE 1
10
15
WO 2014/044961 ^ PCT/FR2013/052129
Emulsions:
Emulsions 1 to 6 correspond to di(2-ethylhexyl) peroxydicarbonate
peroxide emulsions and emulsions 7 and 8 correspond to tert-butyl
peroxyneodecanoate peroxide emulsions, and are characterized in tables 2 and 3:
5
WO 2014/044961 ^ PCT/FR2013/052129
The emulsions according to the invention (emulsions 1-6 and 8) and the
comparative emulsion (emulsion 7) all have organic peroxide mean droplet sizes
corresponding to the strict characteristics demanded in the field under
consideration. On the other hand, one of the main advantages of the present
5 invention lies in a major lowering in the viscosity and in the tlow time of the
resultant peroxide emulsion. This is because the viscosity of the emulsions
resulting from the stabilization of the surfactants of the present invention has been
reduced hy at least a factor nf 3- indeed even a factor nf 5; with respect to the
comparative emulsion. This very significant improvement in the viscosity directly
10 influences the flow time, involving a very great reduction in the flow time with
respect to the comparative test.
Generally, a concentrated 50% by weight peroxyester emulsion is slightly
more fluid than a concentrated 60% by weight peroxydicarbonate emulsion. In the
same way as for the peroxydicarbonate emulsions, the peroxyester emulsions
15 stabilized by the surfactants according to the invention are more fluid than that
stabilized by partially hydrolyzed polyvinyl acetate. This is because the viscosity
of the peroxyester emulsion comprising the surfactant Remcopal®20 has been
reduced by a factor 6 with respect to that comprising a PVA (emulsion 7). These
very good results make it possible to drastically reduce the time for pumping and
20 introducing the peroxide emulsions into a reactor for the polymerization of vinyl
monomer of vinyl chloride type.
It should be noted that the tests presented here do not include diacyl
peroxides but the results obtained on peroxyesters and peroxycarbonates make it
possible to envisage similar results with diacyl peroxides, since diacyl peroxides
25 have formed the subject of preliminary tests as satisfactory as those obtained with
the peroxyesters and peroxydicarbonates.
The emulsions produced with an emulsifying agent according to the
invention (emulsion 2 below) and two comparative protective colloids of partially
hydrolyzed polyvinyl acetate type (emulsions 1 and 2 below), at a degree of
30 hydrolysis of the PVA of respectively 72-73% (PVA 73) and 42-45%
(PVA 42-45), are stored at -20°C for several months. The characteristics are
measured after different storage times. The results are presented in table 4:
The emulsion comprising the emulsifying agent of ethoxylated castor oil
5 type (emulsions 2 and 3) according to the invention and that comprising a
protective colloid of partially hydrolyzed polyvinyl acetate type (emulsion 1)
make it possible to retain a virtually constant mean droplet size and viscosity after
a minimum of 4 months of storage.
Nevertheless, the results show a clear advantage for the composition
10 according to the invention (emulsions 2 and 3) from the viewpoint of the criterion
of the droplet size. This is because, whether from the viewpoint of the mean size
(d50) or the maximum size (dioo), the composition according to the invention
displays results far superior to the composition comprising PVA: the peroxide
mean droplet size (d50) in the composition according to the invention is more than
15 25% lower than that of the composition with PVA, while the maximum droplet
WO 2014/044961 PCT/FR2013/052129
size (dioo) of the composition of the invention is lower by approximately 25% to
close to 35% than that of the composition with PVA.
The viscosity of the emulsion according to the present invention remains
very fluid and less than 300 mPa.s (measured according to the standard
5 DIN 53019 with a Viscotester Haake VT550 at -10°C and for a shear rate of
100 s"1), the flow times remain less than 50 seconds and preferably less than 30
. seconds and the maximum sizes dioo do not exceed 2U urn (micrometers),
pmfrrahly Ifl (im (micrometers).
On the other hand, only the emulsion comprising a surfactant according to
10 the invention makes it possible to retain a virtually constant flow time throughout
the storage time of at least 4 months.
Generally, only the aqueous peroxide emulsion compositions according to
the invention make it possible to solve in a particularly satisfactory fashion the
two major technical problems, namely the enlarging of the peroxide droplets over
15 time or in other words the stability of the emulsion, and the often excessively high
viscosity of the emulsion under cold conditions, resulting in particular in
unsatisfactory flow times.

We Claim:
1. An aqueous organic peroxide emulsion composition devoid of
5 protective colloid agent, consisting of:
- from 10% to 65% by weight of one or more organic peroxides,
- from 2% to 25% by weight of at least one antifreeze agent,
- from 0.01% to 10% by weight of an emulsifying agent,
- optionally at least'one additive,
10 water, the amount of which is determined so as to form the remainder of
the composition (up to 100%), " ' ' '
• characterized'in'that the emulsifying agent consists of a nonionic surfactant
chosen exclusively from: - ' "
- a block copolymer comprising at least one alkylene oxide block; or
15 - a block copolymer comprising at least two alkylene oxide blocks; or
- an alkoxylated fatty alcohol; or
- an alkoxylated fatty acid; or
- an alkoxylated (hydrogenated or nonhydrogenated) vegetable or animal
oil; or
20 - a mixture of several of these components.
2. The composition as claimed in claim 1, characterized in that the
alkoxylated vegetable or animal oil is chosen from ethoxylated derivatives of
mono-, di- or triglycerides and their mixtures.
25
3. The composition as claimed in claim 1 or 2, characterized in that the
alkoxylated vegetable or animal oil comprises a mixture of:
ethoxylated glycerol connected or not connected to one or more chains of fatty
acids; the latter being or not being ethoxylated,
30 - fatty acids ethoxylated on the acid functional group and/or on the hydroxyl
functional group carried by the fatty acid chain, and also
variable proportions of fatty acids, of glycerol and of mono-, di- or
triglycerides.
4. The composition as claimed in any one of claims 1 to 3, characterized
in that the fatty acid comprises an aromatic or nonaromatic, saturated or
unsaturated, cyclic or noncyclic and linear or branched chain of 4 to 60 and
preferably 4 to 20 carbon atoms and between 3 and 80 ethylene oxide units,
5 preferably between 20 and 40. ' • . ..
5. The composition as claimed in any one of the preceding claims,
characterized in that the vegetable oil is ethoxylated or ethoxylated hydrogenated,
such as, in particular, an ethoxylated castor oil or ethoxylated hydrogenated castor
10 nil
6. The composition as claimed in claim 1, characterized in that the fatty
alcohol comprises an aromatic or nonaromatic, saturated or unsaturated, cyclic or
noncyclic and linear or branched chain of 4 to 60 and preferably 4 to 20 carbon
15 atoms and between 3 and 80 alkylene oxide units, preferably between 20 and 40.
7. The composition as claimed in claim 1, characterized in that the block
copolymer comprises at least two alkylene oxide blocks, said alkylene oxide block
comprising between 5 and 80 units.
20
8. The composition as claimed in claim 6, characterized in that the
alkylene oxide units are ethylene oxide units alone or ethylene oxide and
propylene oxide and/or butylene oxide units.
25 9. The composition as claimed in any one of the preceding claims,
characterized in that the nonionic surfactant is present at a concentration of
between 0.05% and 5% by weight in the emulsion, preferably of between 0.1%
and 3% by weight.
30 10. The composition as claimed in any one of the preceding claims,
characterized in that it comprises more than 30% by weight of one or more
organic peroxides, preferably more than 45% by weight.
11. The composition as claimed in any one of the preceding claims,
characterized in that the organic peroxide or peroxides are chosen from
peroxyesters, peroxydicarbonates and/or diacyl peroxides.
5 12. A process for the preparation of the composition as claimed in any
one of the preceding claims, characterized in that it comprises the stages,
optionally successive, of:
- dispersion of the antifreeze agent, optionally at least said additive and also
the emulsifying agent in water in order to obtain a homogeneous aqueous phase,
10 then
- the peroxide is added to the aqueous phase, and
- the mixture thus formed is emulsified during an emulsion stage at a
temperature of less than 5 °C.
15 13. The use of the composition as claimed in one of claims 1 to 10 in the
polymerization or the copolymerization of ethylenically unsaturated monomers.
14. The use of the composition as claimed in claim 13, characterized in
that the ethylenically unsaturated monomers comprise vinyl chloride.