Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
4q
The invention relates to a method of preparing polyvinyl chloride
and copolymers of vinyl chloride by polymerization in seeded microsuspension.
It also relates to the resultant polyvinyl chloride and copolymers.
Polymerization in microsuspension, or fine suspension, is under-
stood as being polymerization, in the presence of initiators soluble in or-
ganic material, of at least one monomer dispersed by powerful mechanical means
in an aqueous medium containing an emulsifier as stabili~er, in order to ob-
tain a dispersion of particles of an average diameter less than 5 microns.
It is known, from Canadian Patent No. 875,050 issued on July 6,
1971 to Produits Chimiques Pechiney-Saint~Gobain, to prepare polymers of
vinyl chloride in microsuspension, in the presence of a seeding product con-
taining all the ;n;tiator necessary for polymerization. However, when poly-
merization is carried out so as to obtain a latex with a polymer concentration
of over 45%~ the high viscosity of the medium necessitates slower agitation,
owing to the mechanical instability of the latex formed. This slow agitation
leads to a decrease in the coefficients of exchange, which means that the
polymerizing time has to become longer.
Moreover when the polymers obtained are used to prepare plastisols,
the plastisols are difficult to use because of their dilatance, i.e. the
increase of their viscosity with the speed gradient, and because the minimNm
proportion of plasticizer that can be used is 50 parts per 100 of polymer.
It is also known that, in the case of polymers of vinyl chloride
prepared by polymerization in emulsion, the use of a plastisol is improved if
the polymer comprises elementary particles forming at least two populations
which have particles of different sizes. This plurality of populations can be
1082~7
obtained by mixing scveral latices comprising particles of different sizes,
but the mixture cannot be made at a high concentration. Another solution
consists of simultancously preparing the various populations of particles by
l~o~ymcrization in cmulsion of at least one monomer in the presence of several
sccdirl~ ~roducts prc~arod by polymerization in cmulsion. ~lowever, this oper-
ation is very tricky, for the quantity of emulsifier used has to be stipulated
and limited and its introduction require~ special care, that is to say, a
specific introductîon all the time, in order to avoid nucleation of new par-
ticles which would limit the polymer concentration of the latex obtained.
Moreover it is difficult to make seeding products with particles of very
small sizes which are measured and homogeneous, since the slightest variation
in particle size results in variation in the ratios of the dimensions and in
the proportions of the various populations obtained after polymerization.
The method of the invention avoids these drawbacks and enables
latices to be prepared by polymerization in microsuspension, without any
limitations, precautions or difficulties; the latices having a polymer con-
centration well over 45% by weight, a low viscosity and a reproducible par-
ticle size. Furthermore, the polymers thus obtained are easy to convert and
more particularly adapted to give plastisols which may contain very little
plasticizer but which are nevertheless easy to use.
According to the invention there is provided a method of pre-
paring a polymer of vinyl chloride which is polyvinyl chloride or a copolymer
containing at least 50% by weight of vinyl chloride and at least one copoly-
merizable monomer, whioh method comprises polymerizing the corresponding
monomer or monomers in microsuspension, in the presence of a first seeding
product in the form of a dispersion of particles of a vinyl polymer previously
prepared by polymerization in microsuspension, the particles of which contain
at least one initiator soluble in organic material, without any complimentary
addition of initiator, characterized in that polymerization is carried out in
the presence of one or more other seeding products in the form of dispersions
of particles of vinyl polymer, the sizes of which differ from one another and
from the particle size of the first seeding product.
C
. ~ - 2 -
1082~7
Thus, the method of preparing polymers of vinyl chloride com-
prises polymeri~ing the corresponding monomer or monomers in microsuspension,
in the presence of a seeding product in the form of a dispersion of
2a -
10~ 47
particleq o.f a ~7n,y 1 polymer previousli ~rcparcd by polymeliza-
tion in microsuspension, the p~rticles of which contain at
least one initi~tor soluble in organic mate~rial, without any
complementary addition of initiator. The method is chaxacter-
ized in that polymerization is carried out in the presence ofone or more other seedin~ products in the form of dispersi.ons
of particles o vinyl polymer, in which the sizes of the par-
ticles differ from one another and differ from that of the
first seeding product; the particles may contain at least one
initiator.
Polymers of vinyl chloride refer to polyvinyl chlor-
ide and to copolymers containing at least 5~/0 by weight of
vinyl chloride and at least one monomer which is copolymeriz-
able with vinyl chloride. The copolymerizable monomers are
those generally employed in conventional methods of copolymer-
izing vinyl chloride. Some examples are vinyl esters of mono-
and poly-carboxylic acids, such as vinyl acetate, propionate
and benzoate; unsaturated mono- and poly-carboxylic acids such
as acrylic, methacrylic, maleic, fumaric and itaconic acid as
well as their aliphatic, cycloaliphatic and aromatic esters,
their amides and their nitriles; vinyl and vinylidene halides;
alkyl vinyl ethers and olefins.
The vinyl polymers, which constitute seeding produ~ts,
are represented by the polymers of vinyl chloride defined above
2~ and by homopolymers of the above-mentioned copolymerizabla
monomers, or copolymers formed by the said monomers.
The polymers of the various seeding products in one
and the same operation may be identical or different.
The use of a vinyl polymer other than vinyl chloride
as a seedin~ product may make it possible to improve certain
~08Z84!7
mech~nic~l prOpQrties or the suitability of the resul'ant poly-
mers for processing such as extrusion or calendering.
~rhe ~irst seeding product nccessary for polymeriæa-
tion is prepared by conventional methods of polymerization in
microsuspension. It is in the form of a dispersion of parti-
cles of poly~er with an average diameter from 0.05 to 1.5jum
and preferably from 0.2 to 1 ~m.
A method of preparing the first seeding product com-
prises using water, a vinyl monomer or a mixture of vinyl mono-
mers, an initiator soluble in organic material and an anionic
emulsifier possibly associated with a non~ionic emulsifier. ~
The monomer or monomers are finely dispsrsed in the water with
the aid of a powerful mechanical means such as a colloid mill,
a high speed pump, a vibrating agitator or an ultxasonic ma-
chine. The micxosuspension obtained is then heated under auto-
genous pressure and with moderate agitation to a temperature
generally from 30 to 65C. When the pressure has dropped,
the reaction is stopped and the unconverted monomer or mono-
mers are degassed.
The initiators which are soluble in organic material
and which are to be used in preparing the seeding product are
represented by organic peroxides such as diacyl paroxides;
among these mention should be made of lauroyl, decanoyl and
caproyl peroxides, tertio'~utyl diethylperacetate, diethyl-
hexyl percarbonate and diacetyl peroxide.
The choice of the initiator soluble in organic mater-
ial depends on the speed at which it decomposes at the temper-
ature used for the reaction. The initiator must in fact be
reactive enough for normal ~uantities, of the crder of 0~1
to 3% by weight relative to the monom r or mixture o~ monomers,
~O~Z~7
to enable t}.e se~di~g produ~t to be prepared within periods of
4 to 20 h~l~s. However, the decomposing speed of the initia-
tor should not be too high, so that the ~lantity oE initiator
decomposed in preparing thc seeding product is not more than
half the quantity of initiator used. It is therefore import-
ant to select an initiator with a half-life time such that the
proportion of initiator destroved in preparing the seeding
product is from 5 to 50O/o by weight of all the initiator used.
In cases where several of euch initiators are used,
it is advantageous to choose ones of different reactivity; the
most reactive initiators are active chiefly during the prepar-
ation of the seeding product, whereas the less reactive initiat-
ors are active meinly during the seeded polymerization of the
vinyl chloride or of the mixture of vinyl chloride and copoly
merizable monomer.
The other seediny product or products are in the form
of dispersions of particles of polymer, which may or may not
contain an initiator; their average diameters, which differ
from one another and from that of the first seeding product,
are from 0.02 to 1.5 ~m and preferably from 0.02 to 0.8 ~m.
For example, in cases where there are only two seeding products,
the average diameter of the particles of the second seeding
product is from 0.05 to 1.5,um and preferably from 0~5 to 0.8
~m; and in cases where there are three seeding products, the
average diameter of the particles ofthe second seedin~ product
is from 0.05 to 1.5 ~Im and preferably from 0.05 to 0.8 ~m, and
the average diameter of the particles of the third seeding
product is from 0.02 to 0.8 ~m and preferably from 0.02 to 0.5
~m.
These dispersions of particles may be obtained by
108284r7
conventio;lal rl~tllods of polymeri~ation in microsusp~nsion or
in cmul~ion.
The preparation o~ the seeding product or products,
other than the first one, when carried out by polymerization
in microsuspension, takes place as described above, but there
is a greater degree of homogenization if the particles to be
obtained are very small. In the method of the invention it is
generally more advantageous to use one or more seeding products,
other than the first, whicn do not contain any initiator. They
are then polymerized with a quantity of initiator such that at
least 8~/o by weight of the initiator is destroyed during the
reaction.
Preparation of the seeding product or products, other
than the first one, when carried out by polymerization in emul-
sion, comprises using water, a vinyl monomer, either alon~ orassociated with a copolymerizable monomer, a water-soluble
initiator and an anionic emulsifier, possibly associated with
a non-ionic emulsifier.
The size of the particles is regulated by the usual
methods suitable for polymerization in emulsion, e.g. by care-
fully choosing the nature and quantity of emulsifier used, by
using seeds and by adjusting the agitating speed.
The reaction mixture is heated under autogenous
pressure and with moderate agitation to a temperature from 30
to 65C. When the pressure has dropped, the reaction is stop-
ped and the unconverted monomer or monomers are degassed.
The water-soluble initiators required for preparing
these seeding products are generally represented by hydrogen
peroxide, persulphates of alkali metals or of ammonium,
possibly associated with water-soluble reducing agents, such
~082~4!7
as ~ulphites or bi~ulphites of alkali metals. The quantities
used vary greatly, dep~nding on the initiating system chosen
ancl a~e just sufficient to insure polymerization within periods
of 4 to lO hours.
In polymerization according to the invention, the
total quantity of the various seeding products used must be
such that the quantity of polymers contained therein is 1 to
5~/O by weight of the sum of vinyl chloride (with or without co-
monomer to be polymerized) plus seeding polymers. A quantity
of over 50% of seeding polymers can be used but is of little
interest, for it is then very large relative to the vinyl
chloride or mixture of vinyl chloride and copolymerizable
monomer, and the advantages of the invention are thus mini-
mized. A quantity of less than 1% of seeding polymers i5 also
of very little intere9t, for the quantity of reactive initiator
contained in the first seeding polymer or in two or more seed-
ing polymers is then very small and does not, in practice,
enable the vinyl chloride or mixture of vinyl chloride and
copolymerizable monomer to be polymerized. It is in fact the
excess initiator in the first seeding polymer or in two or mo~e
seeding polymers that very effectively initiates polymerization
of the vinyl chloride or mixture of vinyl chloride and copoly-
merizable monomer, by setting up a regular reaction speed, as
was shown in French Patent ~o. l,485,547.
The proportion of the first seeding polymer to the
other seeding polymer or pol~mers, which depends on the com-
position of the polymer to be obtained, is from 95/5 to 5/95.
Thus there are several possible ways of carrying out
sesded polymerization. Sone examples of these are:
- Using a first seeding produc~, prepared by
. ~-
108Z8~Y7
pol~m~riz~tion in microsuspension, in which the polymer parti-
clcs contain an initiator soluble in organic material; either
witll a second seeding ~roduct, prepared by polymerization in
~mu:Lsion or in microsuspension, in which the polymer particles,
which are finer than those of the first seeding product, do
not contain any initiator; or with a second seeding product,
prepared by polymerization in microsuspension, in which the
polymer particles, which are finer than those of the first
seeding product, contain an initiator soluble in organic
material
- Using a first seeding product, prepared by poly-
merization in microsuspension, in which the polymer paxticles
contain an initiator soluble in organic material, with a second
seeding product, prepared by polymerization in emulsion or in
microsuspension, in which the polymer particles, which are
finer than those of the first seeding product, do not contain
any initiator: either with a third seeding product, prepared
by polymerization in emulsion or in microsuspension, in which
the polymer particles, which are finer than those of the second
seeding product, do not co~tain any initiator; or with a thi-rd
seeding product, prepared by polymerization in microsuspension,
in which the polymer particles, which are finer than those of
the second seeding product, contain an initiator which is sol-
uble in organic material.
-- Using a first seeding product, prepared by poly-
merization in microsuspension, in which the polymer particles
contain an initiator soluble in organic materlal, with a second
seeding product, prepared by polymerization in microsuspension,
in which the polymer particles, which are finer than those of
the f.irst seeding product, contain an ini.tiator soluble in
lV8Z~7
o.rg~nic ~aterial; either ~i~h a thlrd seedir.g pro~uct, pre~ared
by polymeri~ation in emulsion or in microsuspension, in ~hieh
th~ polymer particles, which are ~iner than those o the second
~e~diny product, do not contain any initiator; or with a third
S seeding product, prepared by polyrnerization in microsuspension,
in whieh the polymer particles, which are finer than those o~
the second seeding product, contain an initiator which is sol-
uble in organic material.
- Using a first seeding product, prepared by polymer-
ization in microsuspension, in which the polymer particles con~
tain an initiator soluble in organic material, with a seeond
seeding product, prepared by polymerization in emulsion or in
mierosuspension, in which the polymer particles, which are
larger than those of the fi.rst seeding produet, do not eontain
any initiator.
- Using a first seeding produet, prepared by polymer-
ization in microsuspension, in which the polymer partieles eon-
tain an initiator soluble in organie material; either with a
seeond seeding product, prepared by polymerization in emulsion
or in mierosuspension, in whieh the polymer particles, which
are larger than those of the first seeding product, do not eon-
tain any initiator; or with a seeond seeding product, prepared
by polymerization in mierosuspension, in which the polymer par-
tieles, which are larger than those of the first seeding produet,
eontain an initiator soluble in organic material; and with a
third seeding produet, prepared by polymerization in emulsion
or in mierosuspension, in which the polymer particles, whieh
ara larger than those of the seeond seeding product, do not
contain any initiator.
- ~sing a first seeding product, prepared by
~.()8284 7
po:Lymerization in microsuspension, in ~lich the polymer par-
ticles contain an initiator soluble in organic material; with
a ~second seeding product, prepared by polymerizatlon in emul--
sicn or in microsuspension, in which the polymer particles,
which are finer than ~hose of the first seeding product, do
not contain any initiator; and with a third seeding product,
prepared by polymerization in emulsion or in microsuspension,
in which the polymer particles, which are larger than those of
the first seeding product, do not contain any initiator.
In a preferred embodiment, a seeding product, pre-
pared by polymerization in microsuspension, in which the poly-
mer particles contain an initiator, is used with a seeding
product prepared by polymerization in emulsion, in which the
polymer particles, which are finer than those of the first
seeding proauct, do not con~ain any initiator.
The proportions of seeding products relative to one
another and the total quantity of seeding products are select-
ed so that the quantity of organo-soluble initiator present in
the particles of polymer is sufficient to effect polymerization
or copolymerization without any complementary addition of ini-~
tiator.
The quantity of water required for polymeriz.ation
according to the invention must be such that the initial poly-
~ler concentration of the seeding products plus the vinyl chlor--
ide, with or without copolymerizable monomer, is from 20 to80% and preferably 45 to 75% by weight of the reaction mi~ture,
allowing for the water content of the seeding products.
In order to improve the stabi.];ity of the microsus-
pension, it may be advantageous to add,before and/or during
polymerization, àt least one anionic emulsifier, possibly
--10--
~()82~
assoclated '.!ith at 1~5. onQ non-ion c ~ulsifi2 . The aniollic
emulsifiers are preferably soaps of fatty acids, alkyl sul-
phates, alkyl sulphonates, alXyl aryl sulphonates, vinyl sul-
phonates, allyl sulphonates, alkyl su]phosuccinates and alka-
line alkyl phosphates; the non-ionic emulsifiers are prefer-
ably polycondensates of ethylene or propylene oxide on various
hydroxylated organic compounds. The emulsifier may be the same
as that or those used in the preparation of the seeding
products.
The quantities of emulsifier may be up to 3% by weight
of the vinyl chloride or mixture of vinyl chloride and copoly-
merizable monomer. These are the quantities generally employed
to obtain a usefu] effect in the reaction. However, quantities
outside the above limits could be used without going beyond the
~cope of the invention, since the only function of the emulsi-
fiers is to stabilize the microsuspension and they have no
effect on the size of the particles.
The reaction medium is heated under autogenous press-
ure to the polymerization temperature determined by the propsr-
ties of the desired vinyl chloride polymer, depending on themolecular weights. The temperature is generally from 10 to
85C and preferably from 30 to 70C.
In order to accelerate polymerization it is recGmmend-
ed to activate the initiator, included in the particles of the
first seeding product and/or of the other seeding products,
with a metal complex which is soluble in organic material and
which is formed throughout the polymerization process by re-
action between a water-soluble metal salt and a complexing
agent which is introduced gradua]ly, as described in Canadian
application Ser. ~0.201,886 , filed June 7, 1974 . The metal
salt is employed in quantities such that the molar ratio of
metal salt to initiator is from 0.1 to 10/1. The metal of
the salt is represented by iron, copper, cobalt, nickel, zinc,
tin, titanium, vanadium, manganese, chromium and silver. The
complexiny agent is represented by mono- or poly-carboxylic
and aJ.kyl phosphoric acids; lactones; ketones and carbazones.
It is used in proportions which may reach molar stoichiometry
relative to the metal salt.
The process of polymerization in microsuspension,
as described above, may obviously be carried out continuously.
Apart from the important advantages of the invention
such as: minimal consumption of initiator; a reaction which is
more regular and possibly shorter than in conventional process-
es; and virtually no incrustation of the reaction zone, thus
~acilitating the heat exchanges which are necessary to obtain
uniform polymerization, there are also more particular advan-
tages: viz. that the invention gives a microsuspension with a
high polymer concentration of up to 75% by weight and with
great fluidity; this gives a concentration of 20 to 75% by
weight; resulting in better exploitation of the polymerizing
and separating means; and that it leads to excep~ional repro-
ducibility of the sizes of particles contained in ~he latex
obtained.
Latices thus prepared contain at least two popula-
tions of particles of different average diameters. Thus, when
two seeding products are used, the two poE~Ilations obtained
have average diameters which, for the larger particles, range
fro~ 0.4 to ~.5 ~m and, for the finer particles, from 0.08 to
1 ~m, in a diameter ratio of larger/finer of 1 to 20/1 and a
weight ratio of 0.1 to 10/1. Similarly, when three seeding
-12-
1082l~4~
prod~cts ~re u~ecl, three poptllations are oktained, with ave--
age (li~ eters ranginy from ~.~ to 2.5 ~m for the lar~Jer par-
ti~les, froo 0.15 to l ~Im for the mediulll ones and ~rom 0.05
to 0.~ um for th~ finer ones. The diameter ratios o~ large
particles/medium particles and of medium particles/fine par-
ticles, which may be similar or different, range from l to
20/l, and the weight ratios of large particles/medium parti-
cles and of medium particles/fine particles, which may be
similar or different, range from 0:1 to ~0/l.
The diameters and weight ratios, within the above
limits, are selected according to the conditions of use for
the polymers formed, such as rheological properties of plasti-
s019 or suitability for extrusion.
The particles of different average diameters result
fxom enla.rgement of the particles of seeding products. By
application of present-day knowledge, the particles of seed-
ing products containing initiator should undergo an enlarge-
ment as defined in French Patent No. 1,485,547; on the other
hand, enlargement should be zero for particles of seeding
products not containiny any initiator. Applicants have found
the enlargement of particles containing an initiator to be
less than expected, whereas particles not containing any ini-
tiator undergo an enlargement which is not negligible, yet
which is proportionally less than that of particles contain-
ing an initiator; this enlargement complies neither with thelaw of enlarge~lent covering polymerization in microsuspension
nor with the law covering polymerization in emulsion.
The vinyl chloride polymers prepared by the method
of the invention are sepa^ated from the polymerizing medium
0 by any known methods such as filtration; co~gulation and
-13-
108Z~47
d7raining; ~aling; _cntri~.lg~l dccantatiorl; and a~omi~ation.
The invention also concernC the polymers thus ob-
tained, which are in the form of powders particularly suitable
for prepar;llg plastisol: ha~irlg Newtonlan or pseudoplastic
behavior with a very low plasticizer content of up to 25 parts
by weight of plastici7.er per 100 parts by weight of polymer,
and a low viscosity which enables coatings to be applied at
very high speed.
The polymers and copolymers of the invention are
applicable to the manufacture of sheets, films, threads, hollo~
bodies, cellular materials or articles molded by calendering,
extrusion, blow extrusion, injection or casting; they may also
be used to obtain coated coverings, cellular materials or
articles molded by any known methods of using plastisols:
coating, rotation molding or di~piny (trempage).
Some examples will now be given by way of illustra-
tion and not by way of limitation of the invention:
ExamPle 1
PreParation of seedinq latex 1 in microsuspension.
The following are mixed:
- 40 kg of vinyl chloride,
- 0.5 kg of lauroyl peroxide,
- 4 kg of a lOo/o by weight aqueous solution of sodium
dodecylbenzenesulphonate,
- enough water .o bring the vinyl chloride concentra-
tion to 43% by weight.
The mixture is homogenized to form a micros~spension
which is then placed in a 120 liter autoclave. It is heated to
52C under autogenols pressure.
When the pressure has dropped, i.e. after 9 hours,
14-
1082~4t7
the unreact~ lnyl chlorid2 i5 deg~ssed. The latex is ob-
t:ainecl with a polyvinyl chloride concelltration of 4~/O by
weight; i~s particles 'nave an average diameter of 0.4~um and
contain 1~5% by weiyht of lauroyl peroxide relative to the
polymer
Preparation of seedinq latex 2 in emulsion
The following are placed in a 120 liter autoclave:
- 60.6 kg of water,
- 2.60 kg of a 10% by weight aqueous solution of
sodium tetradecylsulphonate,
- 0.053 kg of ammonia at 22 Baume~
- 52 kg of vinyl chloride.
The mixture is heated to 52C under autogenous
pressure and this temperature is maintained throughout the
operation~ As soon as the mixture is at 52C, 0.035 kg of
potassium persulphate is introduced. 15 minutes later, 4.75
liters o a l~/o aqueous solution of sodium tetradecylsulphon-
ate is added continuously at a rate of 0.5 liter/hour. After
9-1/2 hours at 52C~ the unreacted vinyl chloride is degassed.
The latex obtained has a polymer concentration of 40.2% by
weight and a particle diameter of 0.12 ~m. The particles do
not contain any initiator.
PolYmerization
The following are placed in a 120 liter autoclave:
- 33.2 kg of water,
- 5.7 kg of latex 1, i.e. 2.3 Xg of polyvinyl chlor-
ide containing 34.5 g of lauroyl peroxide,
- 3.5 kg of latex 2, i.e. 1.4 kg of polyvinyl chlox-
ide,
- 1.5 kg of a l~/o by weight aqueous solution of
.
1(~8~7
S~ iU-[I do~ )erlæen~ s-l].~ onate,
- 55 kg of vinyl chloride.
The mixture is agit:ated, ~1ith th~ agitator at S0
revolutions/min. and heated to 52C. 3 hours later, 2.5 kg
of a l~/o by weight aqueous solution of sodium dodecylbenzene
sulphonats is added.
After 18 hours' reaction, a drop in pressure is ob-
served. When the pressure has dropped 2 bars, the unreacted
vinyl chloride is degassed. A latex is obtained with a polymer
concentration of 54% by weight and a viscosity of 38 cp.
The weight of crusts in the autoclave is only 300 g.
Particle size analysis of the latex obtained shows
the polymer to be made up of two populations of particles with
average diameters of 0.20 ~m and 0.98 ~m respectively. An in-
cr~ase in the ~ize of thJ3 particles of l~tex 2 is noted, al-
though they do not contain any initiator. The fine particles
represent 25% by weight of the polymer.
The latex obtained is atomized, the powder obtained
crushed, and a plastisol prepared by mixing lO0 parts by weight
of polymer and 40 parts by weight of dioctyl phthalate. The
rheological properties of the plastisol are measured:
B - firstly with the aid of a rotary r~eometer of the
Brookfield RTV type (needle ~o. 6, 20 revs/minute, measuring
and conditioning at 25C); the results are given in table l;
- secondly with the aid of a Severs extrusion-type
rheometer (conditioning 2 hours at 25C); the results are set
out in table 2.
3o
g~ ~r ~ ~è ,~ O~ -16-
T~l,E 1.
Brook~ield Viscosity
~ __ _ ___
Conditioning ~t 25C viscosity
hours polses
0.5 : 210
24 ~40
The table shows that, although the plastisol contains
little plasticize~ its viscosity is low and it develops slo~;ly
with the passage of time.
TABLE 2.
Severs Viscosity
Speed gradient Viscosity
;sec-l poises
. . ~
s 235 308
15 , ~80 280
820 260
.. .. _ _ _
A ~tudy of the table reveals the surprising fact
that the viscosity of the plastisol diminishes as the speed
gradient increases; this is charac-teristic of a slight pseudo-
plasticity of the plastisol, which makes it easier to use.
A plastisol consisting of 50 parts by weight of di-
octylphthalate per 100 parts by weight of polyvinyl chloride
also has pseudoplastic behavir that is to say, viscosity
diminishes as the speed gradient increases.
For purposes of comparison three tests are carried
out, with one seeding latex, according to prior art.
Test A in which the procedure is as above, but with
proportions of reagents such that a latex of similar concen-
tration is obtained.
~17-
l()fl2~47
~he fol~wing are placed in ~he re~Lor:
- 32.4 kg of water,
- 6.9 kg of latex 1, i.e. 2.75 ky of polyvinyl
chloridc,
~ 1.5 ky of a 10% by weight aqueous solution of
sodium dodecylbenzene sulphonate,
- 55 kg of vinyl chloride.
The reaction is carried out under the same conditions.
The drop in pressure is observed after 18 hours. After degass-
ing, a precipitated polymer is obtained in the reactor; it is
impossible to recover this by conventional separating processes.
Test B carried out like test A but with an agitator
speed of 30 revs/min. The drop in pressure is observed after
22 hours. The latex obtained has a polymer concentration of
54.5% by weight and a viscosity of 500 cp. Th~ weight o
crusts in the reactor is 2 kg.
Particle size analysis of the latex shows that there
is only one population of particles, with an average diameter
of 1.05~um~
Atomization of the latex is difficult. The product
~r ~;~o/~
B obtained is crushed and two plaoticole are prepared. The re-
sults are given in table 3.
3o
~382~7
TABEE 3.
}'L.A~'r I S OL
: P V C : ~ 0 P : Rheology
: par~s by weight : parts by welght:
:
: 100 : 40 : Impossible to put
: : : into paste form. A
: : : greatly dilatant,
: : : heterogeneous mastic :
is obtained.
: 100 : 50 : Severs Viscosity
: : : Gradient : Viscosity :
. sec~l poises
138 520
: : : 187 770
: : : 255 860
Comparison of tests A and B and example 1 show the
improvement provided by the method of the invention in obtain-
ing latex with a high polymer concentrationand low viscosity.It also shows that the products of the process give plastisols
of gretter fluidity for a low plasticizer content, enabling
coatings to be applied at high speed.
Test C. If in text B, at high concentration, the
proportion of initiator in the seed polymer is increased or
an activating system added in order tG increase the speed of
the reaction, the reaction mixture becomes thermally unstable
due to the poor coefficient of thermal exchange of the reactor
under the conditions of agitation of the viscous medium. Con-
trol of the temperature of the reactor is tnereby lost and thereaction races, giving a latex which is useless, the polymer
not having the required molecular weight.
Example 2
__
Seeding latices 1 and 2 from example 1 are used in
polymerization.
r~_~vlne~ c.c- n
The ollowing are charged into a 120 liter autoclave:
- 28.6 kg of water,
- 5.7 kg of latex 1, i.e. 2.3 kg of polyvinyl
chloride,
- 3.5 kg of latex 2, i.e. 1.4 kg of polyvinyl
chloride,
- 1.5 kg of a 10% by weight aqueous solution of
sodium dodecylbenzene sulphonate,
- 2.7 g of copper sulphate,
- 55 kg of vinyl chloride.
The reaction mixture is agitated, with the agitator
at a speed of 50 revs/min, and heated to 52C.
Continuous introduction of 0.4 liter/hour of a 0.68
g/liter aqueous solution of ascorbic acid is started as soon
as the temperature reaches 52C.
After 3 hours at 52C, 2.5 kg of a 10% by weight
aqueous solution of sodium dodecylbenzene sulphonate is added.
After 9 hours' reaction, a drop in pressure is ob-
served. when pressure has dropped 2 bars, the addition of
ascorbic acid is stopped and the unreacted vinyl chloride is
degassed. A latex is obtained with a polymer concentration of
55% by weight and a viscosity of 40 cp.
The weight of crusts in the reactor is only 120 g.
c'5 Particle size analysis of the latex obtained shows
the polymer to be made up of two polulations of particles. One
constitutes 30% by weight of the polymer and the average dia-
meter of the particles is 0.20~m; the other has an average
particle diameter of 1 ~m and constitutes 70% by weight. The
3 growth of the particles of latex 2 is noted, although they did
-20-
1082~47
not contai.~ ny ini-Liator.
Thc latex is atomized and the polymer obtainea is
converted into 2 plastisols, respectively containing 40 and
5~/, by weight of dioctyl phthalc,te ,~er 100 part~ by weight o~
polymer.
The rheological properties o~' the first plastisol
are set out in tables 4 and 5 and those of the second plasti-
sol in table 6.
TA8LE 4.
Brookfield Viscosity
.
Conditioning at 25C :Viscosity -~
hours ' poises
~ 0,5 ' 180
. 24 300
,
TABLE 5.
Severs Viscosity
. Speed Gradient ,Vlscosity
~sec~l s poises
215 ~ 360
400 , 350
~ 6~0 340
2~ This plastisol has very slightly ps~udoplastic
behavior, as indicated by the decrease in viscosity with the
speed gradient.
Comparison between tables 2 and 5, i.e. examp_es 1
and 2, shows that activation by -the initiator has virtually
no effect on rheological properties; it influences onl~ the
--21--
1()8Z8~7
~a~ltic~n sp~C~.
TAsLE 6.
Severs Viscosity
5. Speed Gradient ; Viscosity
sec 1 poises
112
220 100
540 80
.
ComParative test D. Polymerization in emulsion.
PreParation of seedinq latex 1 in emulsion.
The following are placed in a 120 liter autoclave:
- 61 kg of water,
- 0.053 kg of ~mmonia at 22 Baume,
- 2.6 kg of seeding latex 2 from example 1, i.e.
1,150 kg of polyvinyl chloride,
- 50 kg of vinyl chloride.
The mixture is then heated to 52C under autogenous
pressure and this temperature is maintained throughout the
operation. As soon as the mixture is at 52C, 0.035 kg of
potassium persulphate is introduced and 15 minutes later a
10% by weight aqueous solution of sodium tetradecylsulphonate
is added continuously at a rate of 0.55 liter/hour~ After
9-1/2 hours, the unreacted vinyl chloride is degassed. The
latex obtained has a polymer concentration of 40.5% by weight
with a particle diameter of 0.40 ~m.
Polymerizatio_
The following are placed in a 120 liter a~toclave:
w 45 kg of water,
-2_-
10~7
- O . 053 ~Y OL arlllnollia ~t 22C B~ume,
- 4.10 kg of latex 1, i.e. 1.67 kg of polyvinyl
chk~lide,
- 2.55 kg of latex 2 from example 1, i.e. 1.02 ky of
polyvinyl chloride,
- 40 kg of vinyl chloride.
The mixture is then heated to 52C under autogenous
pressure and this temperature is maintained throughout the re-
action. As soon as the mixture is at 52C, 0.025 kg of potass-
ium persulphate is introduced. 15 minutes later, 5 liters of
~ 10% by weight aqueous solution of sodium dodecylbenzene sul-
phonate is added continuously at a rate of 0.5 liter/hour.
After 10 hours' reaction, the unreacted vinyl chloride
i9 degassed. The latex obtained has a polymer concentration of
15 420/o by we~yht. The weight of crusts in the reactor is 500 g.
Particle size analysis of the latex obtained shows the polymer
to be made up of two populations of particles. One constitutes
39% by weight of the polymer, and the average diameter of its
particles is 0.83 ~m;; the other has an average particle diameter
of 0.34 ~m and constitutes 61% by weight.
The latex is atomized, then converted into plastisol
as in example 1.
The rheological properties are as follows:
TABLE 7.
Brookfield Viecosity
.
Conditioning at 25JC Viscosity
:hours : poises
I
0-5 1800
24 `2000
10~3~7
I'ABLE 8.
Severs Viscosity
.~
; Specd Gradient . Viscosity
sec~l poises
105 2050
160 3100
lgO 4200
Comparison between example 2 and test D shows the
very great difference in particle size between the latices ob-
tained by polymerization in microsuspension and in emulsion,
and consequently the difference between the rheological proper-
ties of plastisols formed from the polymers obtained from these
latices.
Examples 3 to 9.
PolYmerization.
In each of the examples, a 120 liter autoclave is
used, in which there are placed:
- a variable quantity of water,
- 5.7 kg of latex 1 from example 1, i.e. 2.3 kg of i~
polyvinyl chloride,
- a variable quantity or latex 2, the average dia-
meters of the particles being different in each of the examples;
the difference between the average diameters of the particles
is obtained by varying the ~uantity of emulsifier used at the
beyinning of th~ preparation of latex 2 from example 1,
- 0.55 kg of a l~/o by weight aqueous solution of
sodium tetradecylsulphonate,
- 4 g of copper sulphate,
- 55 kg of vinyl chloride
-~4-
~O~
~r~he proc~dur2 i-, the same as in exaM~ie 2, except
that 3.5 kg of the same solution of sodlum tetradecylsulphon-
~tc i~ added during polymerization instead of the sodium do-
decy~benæene sulphonate so]ution.
The variable data of the reaction and the results
obtained are set out in table 9.
A study of the table shows the effect of the total
quantity of seeding latices, the effect of the proportion of
one of the seediny latices relative to the other, and the ef-
fect of the particle diameter of the latices on the formatio~
of crusts during polymerization, and on the particle size of
the latices obtained.
Example 10.
Example 2 is repeated, except that the quantity of
water used for polymerization is 11.7 kg lnstead of 28.6 kg.
At the end of the reaction, the polymer concentra-
tion of the latex is 67% by weight and its viscosity is 60 cp.
The weight of crusts in the autoclave i5 240 g.
The latex contains particles, 29% by weight of which
have an average diameter of 0.19 ~m and 71% by weight of which
have an average diameter of l ~m.
The latex thus obtained is divided into two portions.
- The first portion is atomized under normal condi-
tions at low temperature. The powder obtained is crushed and
converted into plastisol by mixing of 40 parts of diactyl
phthalate per 100 parts of powder.
The rheological p~operties of the plastisol, measured
as in example 1, are summarized in tables 10 and 11.
3o
-25-
1082~W7
..... .......................... ................................... '.
C~ u) ~ O `D O ~
t`~ O O V7 N '~
..... ......................... ...................................
L~ ~ _~
1~ et 1~ ~ CO O N
00 ~ O O 00 ~ ~ O 1
N O U7
1~
..... ......................... ...................................
U~ U) O~
I~ ~ ~ ~ _1 ~ C~ ~1
_1 ~D N O O ~C) Cl~ O O Cl~
N L~l N
...... .......................... ...................................
C~ ~0 ~
~ . . . .
_~ ~ ~ O O O ~ ~ O U~
N If~
,
...... .......................... ...................................
U~
U) N d' 00 d'
o~ I ~ a~ ~
U7 ~ O ~ O g U~ 00 0 0 ~O
...... .......................... ...................................
C~
. Lr~ 00 O
~ t~ ~1 . 00 '7
¢ ~ ~ O O O ~ ~ O u~
..... ......................... .....................................
,
L~ 00 oo~
t~ . . ~ N
o o ~ o o n _ o o o
N N U~ U) t,) ,,~
..... .......................... .....................................
b4 ~b4e b~ ~o ~ ee 0~
.Y ~ . ~~ .
111 O o\ rl .~_~ ~1 N
~1 0 V~ O ~ U) 4~
t~ ~ U~ h ~a~ o
N N''
h h X rl ~ ) ~Q~ C) O ~,1 ,1 ,1
Q) a~V . ~ v
~3 ~~ O h ~ o ~ v) h h h
. ~ ~ ~,1 ~ ~ ~ O ~~ ~ ~ O
C I I I ~ o
................................ ................................... .
- 26 -
1()82~7
TA~LE 10.
Brookfield Viscosity
Conditioning at 25C Viscosity
hours : poises
0.5 220
:
:24 : 460
:
TABLE 11.
Severs Viscosity
. Speed gradient . Viscosity
:sec : poises
.
243 : 313
:
500 302
:830 : 272
This example shows the surprising fact that latices
with a very high concentration and with low viscosity can be
obtained without any crust formation.
- The second portion of the latex is atomized at a
higher temperature. The powder obtained has polyvinyl chloride-
particles with an average diameter of 113 ~m, an apparent mass
per unit volume of 0.69 g/ml and a viscosity inaex of 117.
100 parts by weight of the polymer,thus obtained,are
mixed with 0.5 part by weight of calcium stearate, 4 parts by
weight or a lead stabilizer and 4 parts by weight o~ titani~m
oxide. The composition is then studied with the aid of a
BRABENDER extrusion recorder and a BRABENDER plastograph and
compared with an identical composition prepared with a poly-
vinyl chloride obtained by mass polymerization, with a viscos-
ity index of 101~ - -
10~284 7
T?le results are se-t out in table 12.
TABL~ 12
.
BRAs~wDER PLASTOGRAPEI BRAB~NDER E~;TRIJSION
. RECORDER
POLYMER Gelation : Gelation- Flow : Power : Diarneter .
time : torque : rate :consumed by: of extrud-
: : : machine : ed product:
: : sec. m/g kg/h w mm
:PVC in
examEle 60 3,900 1.73 273 2.31
:Mass
: PV~ : 600 2,350 1.62 233 2.53
swelling
The vinyl polychloride obtained by the method of theinvention is found to gel more quickly, to be extruded slightly
more rapidly and to show less swelling on emerging from the die
than a polyvi~yl chloride prepared by mass polymerization.
Example 11.
- Seeding latex 1 in microsuspension is that prepared
in example 1.
- Prepaxation of seedinq latex 2 in microsusPension.
The procedure is the same as in example 1, preparation
of seeding latex 1, except that 8 kg of a 10% by weight aqueous
solution of sodium dodecyl benzene sulphonate is used instead
of 4 kg, and 0.04 kg of lauroyl peroxide is used instead of
0.~ kg. There is very fine homogenization.
The particles of latex obtained have an average dia-
meter of 0.12 ~m and contain only 0.07% by weight of initiator.
-- Polymerization.
The following are placed in a 120 liter autoclave:
- 28.6 kg of water,
- 5.7 kg of latex 1, i.e. 2.3 kg of polyvinyl chloride,
-2~3-
~08Z8~Y7
-- 3.5 ky Or iat~x 2, i.e. 1.4 kg of polyvinyl
chloride containiny only very little initiator, corresponding
to O.OO~o~0 by weiyht of the monomer present,
- 2.7 g of copper sulphate,
- 1.5 lcg of a 10% by weight a~ueous solution of
sodiurn dodecylbenzene sulphonate,
- 55 kg of vinyl chloride.
The reaction is carried out as in example 2. The
polymer concentration o~ the latex obtained is 54% by weight
lC and its viscosity is 60 cp. The weight of crusts is approxi-
mately 100 g.
The polymer is made up of two populations of parti-
cles with respective average diameters of 0.19 ~m and 1 ~m,
the fine particles constituting 2~/o by weight.
An enlargernent of the particles of latex 2 was noted
although its initiator content was virtually zero.
Example 12.
- ~reparation of seedinq latex 1 in microsuspension.
The preparation of seeding latex 1 in example 1 is
repeated, but with homogenization such that the particle size
of the latex is 0.48 ~m. The polymer concentration is 39.5%
by weight and the particles contain 1.5% by weight, relative
to the polymer, of lauroyl peroxide.
- PreParation of seedinq latex 2 in microsusPension.
The preparatiDn of seeding latex 1 in example 1 is
repeated, with homogenization such that the particle size of
the latex is 0.1 ~m. The polymer concentration is 400/0 and
the particles contain 1.5% by weight, relative to the polymer,
of lauroyl peroxide.
- Polymerization.
-23-
1(18Z~W7
The ~ollowillg are placed in a 120 liter reactor:
- 31.2 kg of w~ter,
- 1.5 kg of a 10% aqueous solution of sodium dodecyl-
benzene sul~honate,
- 9.9 kg of latex l, i.e. 3.9 kg of polyvinyl
chloride,
- 6.35 kg of seeding latex 2, i.e. 2.5 kg of poly-
vinyl chloride,
- 55 kg of vinyl chloride.
The reaction mixture is agitated, heated to 52C
under autogenous pressure and kept at that temperature through-
out the reaction.
After 3 hours' reaction, 2.5 kg of a 10% by wei~,ht
aqueous solution o sodium dodecylbenzene sulphonate is added
to the mixture. The drop in pressure takes place after 12
hours' reaction. When it has dropped 2 bars, the unreacted
vinyl chloride is degassed.
The polymer concentration of the latex obtained is
54% by weight. The weight of crusts is 500 g.
The two populations of particles forming the polymer
have respective average diameters of 0.18~m and 0.99 ~m which
constitute 29 and 71% of the weight.
Example 13
Example 8 is repeated except that the following are
used for polymerization:
- 16.4 kg of water,
- 52.25 kg of vinyl chloride and
- 2.75 kg of vinyl acetate.
The latex obtained has a concentration of 58.1% by
weight and a viscosity of 40 cp. The weight of crusts is low,
-- ~0--
- 108289~7
at 150 g. llle polyrncx ls made up of 22% by weight o~ particles
~it:h an a-~ex.lc3e diameter of O.Z2~m and 78% by wei~ht of parti-
Cle9 with an average cliameter of 1.05 ~m.
The latex is atomized; the product obtained is a
copolymer containing 3.6% by weight of ~-inyl acetate. The
rheological properties of plastisols containing different
quancities of dioctyl phthalate are gi~en in table 13.
TABLE l3.
:
: D O P : Brookfield : Severs
:
:parts/100 : viscosity :(poises) Speed gradient : Viscosity
:of polymer: 1/2 hour : 1 day : (sec~l) : (poises) :
280 660 : 100 ; 700
: : : (390 :(390
:100 :2~0
: : : (940 :(240
:
: : : (1000 : (70
: 60 : 30 35
: : : (2600 (58
A low viscosity plastisol containing 40 parts by
~0 weight of dioctyl phthalate per 100 parts by weight of vinyl
chloride/vinyl acetate copolymer is found to be obtained; this
is impossible with previous processes.
Example 1-~
- Seeding latex 1 used is that from exarnple 1.
- PreParation of seediny latex 2 in emulsion.
The procedure is eactly the same as in example 1.
The diameter o~ the particles obtained is 0.115 ~m.
- Polymerization'O
Example 2 is repeated.
At the end of the react~oll the concentration of the
1()8*~!7
]a~ 54.g~0 ~-y w2icJht a~ld its viscosi~y is 40 cp. ~rhe
weight of crusts in the autoclave is 150 g.
The polymer o tlle latex is made up of 69~/o by weight
of particles with an average diameter of 0.98,um and 31% by
weight o~ particles with an average diameter of 0.19 ~m.
Comparative tests E and F in emulsion with two seed-
ing latices of the emulsion type.
- Preparation of seeding latex 1 in emulsion.
The procedure is like that followed in preparing the
seeding latex in comparative test D of example 2.
- Preparation of seedinq latex 2 in emulsion. `~
e) The preparation of seeding latex 2 from example 1
is repeated, except that 1.04 kg of a 10% by weight aqueous
colution of sodium tetradecylsulphonate is used instead of 2.6
ky, and no sodium tetradecylsulphonate is introduced during
polymerization. The particle diameter of the latex obtained
is 0.031 ~m.
f) The procedure is exactly the same as in e). The
particle diameter of the latex obtained is 0.025~um.
Two polymerizations ~re carried out as follows, one
with latex 2e and the other with latex 2f. The proportions
are such that the weight ratio of the two populations of par-
ticles and the diameter of the largest particles in the latex
to be obtained are close to those of the latex in example 14.
The following are charged into a 25 liter autoclave:
- 8000 g of deionized water,
- seeding latices 1 and 2 in varying quantities
- vinyl chloride in a ~antity such that the weight
of monomer and seeding polymer is 7000 g.
3 The mixture is agitated and heated to 52C. ~s soon
~0~284 7
as the rnixtllre t'eclC-n~S that temperatu~e, ~ g of ~onium per-
sulphate is introduced. One hour la~el^, Z liters of a 1~75'~/o
by weight aqueous solution of sodium dodecylbellzcne sulphonate
is introduced continuously at a rate of 0.23 liter/hour.
When pressure is at 5 bar~" the unreacted monomer is
degassed.
The operating data and results of tests E and F are ~ -
summarized in table 14 and compared ~iih examples 2 and 14.
A study of this table shows that a slight difference
in the particle diameters of seeding latices Z in polymeriza-
tion in microsuspension results in virtually no differences in
the particle size of the products obtained or in the rheologi-
cal properties. On the other hand, an identical difference
between the particle diam~ters of seeding latices 2 in poly-
merizatJon in emulslon ~eads to significant differences in
the particle size of the products obtained and consequently
in their rheological properties. In t'mis case there is no
reproducibility of the process.
3o
~08Zt~7
.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
~r
~r 0~ u~ a~ o~ ~ o
~ ~ a~ l
o ~ o ~ o ~ o , ~ o CO
~ ........ ...................... ................... ...................
1~ ~
o ~ ~ o o l l
r o ~ o o
.. .. . . oU~
O q O N ~1 00 0 CO ~ I I
........ ........ ..................... ........... ..... ................ -
O ~ O ~D ~ O
O ~ ~ ~1 _I
.. .. . . ~r ~
o ~r o o o co o N ~ 0
........ ...................... .................. ....................
o ~
li3 O O ~O D N ~1
o ~r o o o co o ~I N ~ O O
................ ...................... .......................................
e ~ ~ dP D~ ~ I ~
.~ .~ ~i a~
3C 3 O
1~ 1~ ~ , ~
~1 ~ ~ L~ o I~ o
~2 ~ Pl~ ~ 8 8 ~ ~
~ o ~ .,~ ~rl ~I In
~: 1:~ 0 h ~ ~ ~ J~ :~ O
O ~ ) lll 1~ ,a ~4 o ~J
.~ ' ~'~1 g .4 ~ U~ ~rl ''~
~ 11 ~ I ", I o ~ ~ -o~ ~ 8
.~ l I I l ~ ~ P. .q ~ ~q
, ~ ~ C~ ~, ~ ~ ~
, X ,~ o .,, ,, , .Y
2 ~ ~ ~ ~ ~ P.
~ P~ m
............. ...................... .......................................
108ZB~7 ~
- Pre~ ion of se~dinq l~ta~ 1 in microsuspension.
The preparation of seecling lal:ex 1 from example 1 is
repe;lted with homogellization such that ~he average particle
diameter of the latex is 0.25 ~m. The polymer concentration
of the late~ obtained is 40O/o by wei~ht and the particles con-
tain 1.5% by weight, relative to the polymer, of lauroyl per-
oxide.
- Preparation of seedinq latex 2 in emulsion.
Procedure is the same as in comparative test D in
example 2, but with 0.43 kg, instead of 2.6 kg. of seeding
latex 2 from example 1, i.e. 0.190 kg of polyvinyl chloride.
The latex obtained has a polymer concentration of
40/O by weight, and the diameter of its particles is 0.74 ~m.
- PolYm~riY~ation~
The following are placed in a 120 liter autoclave:
- 52 kg of water,
- 4.95 kg of latex 1, i.e. 2 kg of polyvinyl chloride,
- - 3.15 kg of latex 2, i.e. 1.25 Xg of polyvinyl
~ chloride, -~
- 1.5 kg of a 10% by weight aqueous solution of
sodium dodecylbenzene sulphonate,
- 2.7 g of copper sulphate,
- 50 kg of vinyl chloride.
Polymerization is carried out in the same way as in
example 2.
The latex obtained has a polymer concentxation of
43% by weight. Particle siæe analysis shows it to contain two
populations of elementary particles with respective average
3 diameters of 0.88 ~m and 0.C2;~m~ constituting 10 and ~0~/O by
-35-
~()8;~4~7
wci~ht Or: the poly~er. This confirms the gro~7th of t~-~e parti-
cles oE t:lle 2 seediny latices.
Ex~t~e 16
-- Preparation of seedin~ latex 1 in microsuspension.
_
Preparation is the same as t~lat of latex 1 in example
1.
- Preparation of seedinq latex 2 in emulsion.
The preparation of seeding latex 2 from example 1
is repeated.
- Preparation of seedinq latex 3 in emulsion.
The following are placed in a 120 liter autoclave:
- 65 kg of water,
- 2 kg of a 5% by weight aqueous solution of potassium
laurate,
- 0~$3 kg of ammonia at 22 Baume,
- 52 kg of vinyl chloride.
The mixture is then heated to 52C under autogenous
pressure and this temperature is maintained throughout the
operation. As soon as the mixture is at 52C, 0.035 kg of
potassium persulphate is introduced. After 9-1/2 hours at
52C, the unreacted vinyl chloride is degassed. The latex
obtained has a polymer concentration of 40.2% by weight and a
particle diameter of 0.2 ~m. The particles do not contain any
initiator.
- Polymerization
The following are placed in a 120 liter autoclave:
- 33.2 kg of water,
- 5.7 kg of latex 1, i.e. 2.3 kg of- polyvinyl chlor-
ide containing 34.5 g of lauroyl peroxide,
3 - 1.75 kg of latex 2, i.e. 0.7 k-~ of polyvinyl
-36-
~ o~
cilioridc,
- 1.5 kg of a l~/o by weight aqueous solution of
~odium dodecylkenzene sulphonate,
- 55 Xy of vinyl chloride.
The reaction mixture is agitated, at an aqitator
speed o 50 revs/min and heated to 52C. After 3 hours, 2.5
kg of a 10% by weight aqueous solution of sodium dodecylbenzene
sulphonate is added.
After 18 hours' reaction, a drop in pressure is ob-
served. When the pressure has dropped 2 bars, the unreacted
vinyl chloride is degassed. The latex obtained has a polymer ;
concentration of 54% by weight and a viscosity of 25 cp.
The weight of crusts in the autoclave is only 300 g.
Particle size analysis of the latex obtained shows
the polymer to be made up of three populations of particles,
with respective average diameters of 0.16 ~m, 0.40 ~m and
0.97 ~m, constituting respectively 16%, 2~/o and 64% of the
weight of polymer.
Comparison between latex of example 16 and latex of
example 1 shows that, for a same polymer concentration, the
viscosities are different.
Example 17
The seeding latex 1 used is that from example 1.
- Preparation of seedinq latex 2 in emulsion
The preparation of seeding latex 3 from example 16
is repeated.
- Preparation of seedinq latex 3 in emulsion
This is prepared like the seeding laiex in compara-
tive test D of example 2.
-3/-
lOBZ84!7
- Pol~m_r_ ation
The following are placecl in a 120 liter a~ltoclave;
- 33.2 kg of water,
- 5.7 ky of latex l, i.e. 2.3 kg o~ polyvinyl chlor-
ide containing 34.5 y of lauroyl peroxide,
- 10.5 kg of latex 2, i.e. 4.2 kg of polyvinyl
chloride,
- 10.5 kg of latex 3, i.e. 4.2 kg of polyvinyl
chloride,
- 1.5 kg of a 10% by weight aqueous solution of sodium
dodecylbenzene sulphonate,
- 55 kg of vinyl chloride.
Polymerization is carried out as in example 16 and
the latex obtained has a polymer concentration of 53% by weight
and a viscosity of 45 cp.
The weight of crusts in the autoclave is only 320 g.
Particle size analysis shows the latex to contain
three populations of elementary particles with respective aver-
age diameters of 0.26 ym, 0.54 ~m and 0.92 ~m, constituting
22, 32 and 46% by weight of the polymer.
Example 18
Seeding latices l and 2 from example 16 are used in
polymerization.
- Pr~paration of seeding latex 3 in emulsion
The preparation of seeding latex 2 from example 1 is
repeated, but with 1.04 kg of a 10/~ by weight aqueous solution
of sodium tetradecylsulphonate irstead of 2.6 kg and without
the introduction of sodium tetradecylsulphonate during poly-
merization. The partjcle di~neter of the latex o~tained is
0.031 ~m.
-3~-
10~2~
- ~olvmerizd~ n
This is done under t~le salne conditions as in
excm~ple 16.
The latex obtained has a viscosity of 22 cp and con-
tains three populations of particles constituting 13, 22 and
65% by weight of the polymer, with respective average diameters
of 0.067 ~m, 0.19 ~m and 0.97 ~m.
Example 19
- PreparatiDn of seedinq latex 1 in microsuspension
The preparation of seeding latex 1 from example 1 is
repeated.
- Preparation of seedinq latex 2 in emulsion
The following are placed in a 25 liter autoclave:
- 9.1 kg of water,
- 0.75 ky o~ s~eding latex 3 of example 18, i.e.
0.3 kg of polyvinyl chloride.
These are agitated and heated to 75C, and this tem-
perature is maintained throughout the operation. As soon as
the mixture is at 75C, 12 g of potassium persulphate in solu-
tion in 100 g of water is introduced. 6 kg of butylacrylate
and one liter o~ an aqueous solution containing 30 g of sodium
pyrophosphate and 60 g of sodium dodecylbenzene sulphonate are
then added simultaneously and continuously over three hours.
After 8 hours, the reaction is stopped; the latex obtained
has a polymer concentration of 33% by weight and an average
particle diameter of 0.09 ~m.
- Polymerization
The procedure is as in example-l but using 4.25 kg
of latex 2 above, i.e. 1.4 kg of polymer.
3 The lat2x obtained has a concentration of 52% by
weight and a viscosity of 4n cp.
-3~-
~V~
ïlle ~ieig]lt of C'I.UStS ill ~he au~ociave is only 400 g.
Particle si~e arlal.ysis Oc the latex obtained shows
the polyrn~r to be made UE~ of two populatic)ns of par~icLes
with re.spective average cliameters of O~].B ~Im and 0.96~um,
the fine particles constituting 30% by weight.
3o
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