Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PEROXYESTER-MONOSACCHARIDE REDOX CATALYST SYSTEM
FOR VINYL CHLORIDE POLYMERIZATION
FIELD OF THE INVENTION
This invention relates to a process for the
polymerization of vinyl chloride, in bulk or suspension
systems, using a redox catalyst system consisting of a
peroxyester and a monosaccharide or monosaccharide carboxylic
acid ester.
BACKGROUND OF THE INVENTION
The suspension polymerization of vinyl chloride is
generally carried out at temperatures below 70~C using organic
soluble initiators. Although lauroyl peroxide was earlier the
most ~idely used catalyst, in recent years other low temperature
catalysts including azobisisobutyronitrile, dlisopropyl
peroxydicarbonate, t-butyl peroxypivalate and mixtures thereof f
ha~e been adopted. These and other catalysts are described in
Pennwalt Corporation, Lucidol Division, Technical Bulletin
30.90, "Free Radical Initiators for the Suspension Polymeri-
zation of Vinyl Chloride" (1977).
The choice of initiator is dictated by its half-life
and by its influence on the polymexization process and the
properties of the poly(vinyl chloride) produced thereby.
The polymerization of vinyl chloride is characterized
by a short induction period, followed by a gradually increasing
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rate of polymerization~ Luring the earlier ~tages of th~ polym~r-
ization, the reaction rate i8 lower than the maximum ~o that the
capacity of the reactor i~ not fUlly utilized. Peroxye~ter~
reduce the induction period and, due to a more constarlt rate o~
polymerization, increase reactor productivity. ~uxther, peroxy-
ester~ can generally be used at levels below tha~ needed for per-
oxides and give much less chain bra.nch.ing ~uring polymerization.
Although peroxyester~ ~uch as dii~opropyl peroxydicar-
bonate and t-butyl peroxypivalate offer num~rou~ advantage3 in
vinyl chloride polymerization, ~heir di~advantages include the
necessi~y for low temperature ~hipping and ~orage and decrea~ed
efficiency at elevated temperatures.
The use of peroxyesters having higher deco~po~ition
temperature~ i8 not feasible in present poly(vlnyl chloride)
production facilities due to the higher mcnomer pxe~ures involved
and the low molecular weight and poorer stabil~ty of th~ re~ulta~t
resins. Neverthele~s, the handling ad~antage~ of ~u~h peroxy-
esters makes ~heir use extremely attractive.
The use of higher temperature cataly~t~ at lower temper-
atureR i~ a common practice in polymer technology. Thu~, redox
~y~tems ~uch a~ anunonium per~ulfate - ~odium metabisulfite and
hydrogen peroxide - ferrous ~ulfate are used in emulsion polymer-
ization while benzoyl peroxide - dimethylaniline and methyl ethyl
ketone peroxide - cobalt naphthenate are used in ~tyrene - un~at-
urated polye~ter polymerization.
Reducing agent~ use~ in conjunctlon with monomer-~oluble
peroxye~ters in the polymerization o vinyl chloride include
potas~ium me~abisulfite (N. ~ischer and C. La~bling, French Pa~0nt
2,086,635 (1972), ~odium bi~ulfi~e ~H. Minato, K~ ~ashimotG, and
T. Yasui, JapanD Patent 68 20,300 (l968), ~odium bisulfite -
cupric chloride (B. K~ Shen, U. S. Patent 3,668,l94 (l972), ~odium
dithionite - ferrou~ aulfate ~H. Mi~atoO Japan. Pa ent 70 04, ~g4
~l970~ a~d trialkyl boron (R. Kato and I. Soemat~u, Jap~n. Patent
5498('65~ (19651t A. V. Rya~ov, V. A. Dodonov, and YO A. Iv~nova,
Tr~ Xhim. Xhim. Tekknol., l970, 238~ Stockho~ upe~fo~Pat
Fabrik~ A/B, Brit. Patent 961,254 (lg64).
- Variou~ sugars including ~luco~e, dsxtrose, fructo~e
and sorbose have been used as activator~ in ~! activated recipes"
for the emulsion polymerization of butadieno and ~tyrene. The~e
so-called "sugar-iron-peroxide" recipes con~n benzoyl peroxide,
cumene hydroperoxide or other hydroperoxides as oxidant, ferric
or ferrouc ~alt~ a3 reducing agent, a sugar a~ "activator" and,
generally, sodium pyropho~phate as complexing agent 1F. A. Bovey,
I. M. Kolthoff, A. I. Medalia, and ~. J~ Meehan, "Emulsion Polymer-
ization", Interscience Publishers, New York, 1955, pp. ~5-89 and
374-390). Dextrose ha~ al~o been used in a cumene-hydroperoxide-
ferrous sulfate-sodium pyropho~phate catalyst ~ystem for the graft
copolymerization oE ~tyrene and acrylonitrile onto a polybutadiene
latex ~W. C. Calvert, U. S. Patent 3,238,275 (l9661 To Sakuma and
I. Maka~ura, Japan. Patent 13,635 ~'66) (l966).
SUMM~RY OF T~E I~VENTION
~ n object of the pre~ent invention i~ to provide a
process for th~ polymerization of vinyl chlorid*, in the pre~o~c~
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of peroxygen compounds at temperatures at which thé latter are
stable and readily handled. Another object of the present inven-
tion is to provide a process for the bulk and suspension polymer-
ization of vinyl chloride at temperatures below 70C using per-
oxygen compounds which, at ~hese temperatures, do not generate
free radicals at a sufficient rate to initiate polymeri~ation at
a practical rate, if at all.
It has now been found that this improvement in vinyl
chloride polymerization can be achieved by utilizing a redox cata-
lyst system consisting of a peroxyester and a monosaccharide ormonosaccharide carboxylic acid ester.
Thus the present invention provides in a broad aspect a
process for the preparation of polymers and copolymers of vinyl
chloride, which consists in polymerization in bulk or suspension,
in the presence of a redox catalyst system consisting of a peroxy-
ester and a reducing agent seIected from the class consisting of a
monosaccharide, a carboxylic acid ester of a monosaccharide, a
disaccharide, and a carboxylic acid ester of a disaccharide.
In another aspect the invention provides a process for
the preparation of polymers and copolymers of vinyl chloridP, which
consists in polymerization in bulk or suspension, in the presence
of a redox catalyst system consisting of a peroxyester, a reducing
agent selected from the class consisting of a monosaccharide and
a carboxylic acid ester of a monosaccharide, and a stannous or
antimony (III) car~oxylate.
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DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, the polymerization
of vinyl chloride is carried out in bulk or suspension, under the
conditions applicable thereto and well known to those skilled in
the art, using a catalyst system consisting of a monomer-soluble
peroxyester and a reducing agent which is a monosaccharide or a
carboxylic acid ester of a monosaccharide.
The half-life of a free radical catalyst is the time
required for 50% decomposition at a particular temperature. The
half-life is only relevant as regards the temperature at which it
is desired to conduct a polymerization, e.g. the polymerization
of vinyl chloride below 70C to produce poly(vinyl chloride)
with greater thermal stability than polymer produced above 70C.
The ha~f-life of a peroxyester refers to thermal decomposition
and,consequently, if a polymerization is to be conduoted ~t 50C, a
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catalyst with a half-life of 20 hours or less at 50C, can be
used for the polymerization, e.g. t-butyl peroxypivalate or
t-butyl peroxyneodecanoate, as is well known to those skilled
in the art.
However, if it is desired to conduct the polymeri-
zation with a catalyst which does not require refrigerated
shipment and/or storage, which are required by t-butyl
peroxypivalate and t-butyl peroxyneodecanoate, than in
accordance with the present invention, a catalyst with a
half-life of more than S0 hours at 50C can be used in the
presence of a suitable reducing agent, e.g. t-butyl
peroxyoctoate which has a half-life of 133 hours at 50C in the
absence of the reducing agent may be used.
Alternatively, if it is desired to conduct poly~.erization
at or below 25C, in oxder to maintain better control of the
reaction exotherm or to obtain a higher molecular weight, less
branched polymer, the aforementioned peresters, despite the
requirement for refrigerated shipping and storage, having half-
lives of more than 150 hours at 25C, may be used in the presence
of a suitable reducing agent.
The process of the present invention utilizes a peroxy-
ester, in the presence of a suitable reducing agent, at a tempera-
ture ~here the peroxyester has a half-life of more than 50 hours
in the absence of the reducing agent.
The peroxyesters which may be used in the process of
the present invention are the alkyl and aralkyl peroxyesters of
aliphatic or aromatic carboxylic acids or carbonic acid and may
be represented by the structural formula
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R-O-O-C-R'
where R is an alkyl, aralkyl or alkoxycarbonyl group, R' is an
alkyl, aralkyl, aryl or alkoxy group, and Rand R' are the same or
different. When R and/or R' contain alkyl or aralkyl moieties,
the latter may contain 1-20 carbon atoms and may be primary,
secondary or tertiary~ linear or branched, acyclic or cyclic,
saturated or unsaturated and may contain non-hydrocar~on substitu-
ents includ~ halogen and hydroxyl groups. When R' is an aromatic moiety,
it may be uns~bstituted or may contain hydrocarbon, halogen and/or other
substituents.
The peroxyesters may be monoperoxyesters or the
diperoxyesters of dicarboxylic acids or diols.
Representati~e peroxyesters include t-butyl peroxy-
acetate, t-butyl peroxyisobutyrate, t-butyl peroxypivalate,
t-butyl peroxyneodecanoate, t-butyl peroxybenzoate, t-butyl
peroxyoctoate, t-butyl peroxyl2-ethylhexanoate?, t-amyl peroxy-
neodecanoate, cumyl neodecanoate, isobutyl peroxypivalate,
sec-butyl peroxybenzoate, n-butyl peroxyoctoate, t-butyl peroxy-
3,3,5-trimethylhexanoate, t-butyl peroxy-2-methylbenzoate, 2,5-
dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, 2,5-dimethyl~2,5-
-bis(benzoylperoxy)hexane/ 2,5-dimethyl-2,5-bis(octanoylperoxy)-
~`hexane, di-t-butyl diperoxyphthalate, t-butyl peroxymaleic acid,
t-butyl peroxyisopropylcarbonate, di(sec-butyl) peroxydicarbonate,
bis(4-t-butylcyclohexyl)peroxydicarbonate, diisopropyl peroxydi-
carbonate, di(n-propyl)peroxydicarbonate, di(2-ethylhexyl)peroxy-
~icarbonate, dicyclohexyl perocydicarbonate, diaetyl peroxydi-
carbonate and the like.
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The process of the present invention i~ carried ou~
with a redox catalyst ~y~t~m consisting of a monomer~~olubl~
peroxygen compound, i.e. a peroxye~ter, and a reductan~ bulk
polymerization, a monomer-soluble reductant i~ required, while
su~pension polymerization permits the u~e of either a monomer-
~oluble or a monomer-insoluble reductant.
The monosaccharides which may be u~ed a~ reduct~nt~ in
the practice of the pr~ent invention include pentose~ a~d hexoaes
wherein the carbonyl group i~ either an aldehyde or a ketone, i.e.
polyhydroxyaldehydes commonly referred to a3 aldose~ and poly-
hydroxyketone3 commonly referred to as ksto~es~
Representative monosaccharides or reducing sugar~ include
arabinose, xylo~e, lyxose, ribo~e, gluco~e, gulo~e, manno~e, allose,
galactose, tallo3e, altrose, ido~e, fructose and sorbo~e.
The carboxylic acid esters of the monosaccharides which
may he u~ed a~ reductants in the present invention include the
ester~ of aliphatic and aromatic carboxylic acids. Th~ aliphatic
carboxylic acid~ contain 1-26 carbon atoms and may be linear or
branched, cyclic or acyclic, saturated or u~saturat~d. The aromatic
carboxylic acids may be sub~tituted or unaubstituted.
~ epre~entative carboxylic acid e~ter~ include the e~t~rs
of acetic acid, propionic acid, butyric acid, octanoic acid, ~tearic
acid, benzoic acid and the like.
The concentration of peroxyester i8 generally 0001~5%
b~ weight of the vinyl chloride, with a preferred concentration o~
0.05-1% by weight. The peroxyester/reduc~ant mole ratio is generally
1/0.01-2, with a preferred mole ratio of 1/0.1-1.
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The redox catalyst s~stem consisting of a peroxyester
- and a monosaccharide or a carboxylic acid ester of a mono-
saccharide may also contain the stannous or antimony (III) salt
of an aromatic or aliphatic carboxylic acid. The presence of
the metal carboxylate permits the use of lower concentrations
of the peroxyester. The monosaccharide/metal carboxylate mole
ratio is generally 1/9.01-1. Representative carboxylates are
derived from aromatic carboxylic acids or aliphatic carboxylic
acids which contain 1-26 carbon atoms and may be linear or
branched, cyclic or acyclic, saturated or unsaturated, inc~uding
the stannous and antimony (III) salts of acetic acid,propionic
acid, butanoic acid, caproic acid, lauric acid, stearic acid
and the like.
The procedures normally used in the suspension
polymerization of vinyl chloride are applicable to the process
of the present invention. Typical procedures are described in
Encyclopedia of Polymer Science and Technology, 14, 339-343(1971)~
The polymerization may be conducted at or above atmos-
pheric pressure. In the usual procedure, the reactor is charged
?O at atmospheric pressure and the pressure rises when the contents
of the reactor are brought to reaction temperature. The pressure
may increase further due to the reaction exotherm andthen re~ain
constant until the conversion reaches about 70~, after which it
decreases rapidly as the reaction continues.
The polymerization temperature may range from -50 to
; +70C for bulk polymerization, although temperatures of 40 to
60C are preferred. Suspension polym0rization may be carried
out at temperatures of +5 to +70C, although preferred temperatures
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are in the 20-60C range.
The concentrations of monomer and water, e.g. about 2/1
weight ratio, and the types and concentrations of suspending
agents are those normally used in suspension polymerization and
are well known to those skilled in the art. Typical suspending
agents include poly(vinyl alcohol?, partially saponified
polytvinyl acetate?, gelatin, methylcellulose, vinyl acetate-
maleic anhydride copolymer and the like. Various emulsifiers
such as sulfonated oils and ethylene oxide condensation products may be
added to control surface tension and particle shape. Buffers may be used,
where necessary, e.g. when gelatin is used as suspending agent. Chain
transfer agents su h as chlorinated hydrocarbons and iso-
butylene may be used in the preparation of low molecular weight
polymer.
Although the pero~yester-~onosaccharide or -~onosaccharide
carboxylic acid ester catalyst system of the present invention is
particularly usefuI in the bulk and suspension polymerization of
vinyl chloride, the redox system may also be used in the copolymer-
ization of vinyl chloride with vinylidene chloride, vinyl acetate,
` 20 and other monomers which undergo copolymerization with ~inyl chloride.
The ~ollowing examples are illustrative embodiments of
the practice of the present invention and are not -to be construed
as limitations on the invention or the claims. Numerous modifica-
tions will be obvious to those skilled in the art.
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EXAMPL~ I
Ao A 4 oz gla~s bottle was charged with the following
~u~pension recipe: .
21 ml dis~illed water (boiled)
1 ml lX aqueouR 801utio~ of Tween 60 (polyoxyethylene
sorbitan monostearate,. P~tlas CneT~ical Ind-
u~tries Inc. )
1 ml lX aqueous solution of Span*60 (sorbitan ~no-
~tearate, Atla~ Chemical Indu~trie~ Inc.. )
2 ml lX aqueou~ solution o~ Methocel*A-15 (methyl
cellulo~e with vi~co~ity of 15 cp0 as ~ 2%
aqueou~ solution, Dow Chemical Ot). )
Nitrogen wa~ bubbled through the aqueou~ ~olution ~or 15 a~inute~.
Ga~eoua vinyl chloride waEI purlied by pa~sage through
two SX aqueous sodium hydroxide 801ution~ dri~d by pa~salge through
a 8i~ I gel column and then condensed with tlle ~ld of a dry ic~
bath. After 0.041 g (0.23 mmole) glucoss zlnd 10 g liquid v~nyl
chloride were added to the E~u~pen~ion recipe, the bottle wa~ clo~ed
with a s~crew cap containing a center hol;~ and a eelf-~aling ga~Xet.
The addition o~ 0.055 ml (0.23 mmole) t-butyl peroxyoctoate (0.5~
by wsight of vinyl chloride) was made by injection through the ga~ket
using a hypodennic syringe. The bot~le wa~ placed in a 50C con~ta~t
temperature bath and shaken for 7 hour~. The botkle was removed from
the bath and the residual monomer was released by insertir~g a needle
in~o the gasket. Th~ yield of poly (vinyl chloride) was 4~,1 g (41%
conver~ ion 3 ~
B. P, l~o~tle was charged in the same manner and with the
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same reactants as in A, except for the omission o glucose. No
polymer was isolated after 7 hours at 50gC.
EXAMPLE II
The procedure of Example I was repeated, using the
same suspension recipe, with 10 g vinyl chloride,0.055 ml ~0.23
mmole) t-butyl peroxyoctoate (0.5~ by weight of vinyl chloride) and 0.02 g
(0.115 mmole) glucose. After 7 hours at 50C, the yield of polymer was
3.9 g (39% conversion).
~ EXAMPLE III
The procedure of Example I was repeated, using the same
suspension recipe, wlth 10 g vinyl chloride, 0.022 ml (0.092 mmole)
t-butyl peroxyoctoate (0.2% by weight of vinyl chloride) and
0.017 g (0.092 mmole) glucose. After 7 hours at 50C, the
yield of polymer was 2.0 g (20% conversion).
EXAMPLE I~
The procedure of Example I was repeated, using the
same suspension recipe, with 10 g vinyl chloride, 0.055 ml (0.23
mmole) t-butyl peroxyoctoate (0.5~ by weight of vinyl chloride)
and 0.041 g (0.23 mmole) sorbose. The conversion was 31% after
20 7 hours at 50C.
EXA~PLE V
The procedure of Example I was repeated, using the
- same suspension recipe, with 10 g vinyl chloride, 0.055 ml
(0.23 mmole) t-butyl peroxyoctoate and 0.041 g (0.23 mmole)
fructose. The conversion was 30~ after 7 hours at 50C.
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EX~MPI~ VI
The proc~dure of Example I was repeated, u~ing the sam~
suspension reclpe, with 10 g vinyl chloride, 0.055 ml (0.~3 mmole)
t-butyl peroxyoctoate and 0.09 g (0.23 mmole) ~-glucose pentaacetate.
The bottle was shaken a~ 50C for 7 hours to yield 4.5 g (45~ con-
version~ polymer.
EXAMPLE VII
The procedure of Example I was repeate~ with 10 g vinyl
chloride, 0.055 ml (0.23 mmole) t-butyl peroxyoctoate and 0.045 g
(0.115 mmola)oc-glucose pentaacetate. After 16 hour~ at 50C the
yield o~ polymer was 7.2 g (72% conver~ion).
~XAMPLE VIII
The procedure o~ Example I wa~r#peated wlth 10 g vinyl
chloride, 0.055 ml (0.23 mmole) t-butyl paroxyoctoato and 0.018 g
~0.092 mmole) ~-glucos2 pentaacetate. The yield of polymer wa~
4.0 g ~40% conversion) after 7 hour~ at 50C~
~XAMPLE IX
The procedure of Example I was ~? peated with 10 g vinyl
chloride, 0.055 ml (0.23 mmole) t-butyl peroxyoctoate and 0.156 g
(0.23 mmola) sucrose octaacetate. The yield of polymer was 3~1 g
(31~h conver~ion) after 7 hours at 50 C.
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EXAMPLE X
A 6 oz glass bottle was charged wi~h th~ following
suspension recipe;
~2 ml distilled water
2 ml 1% aqu~ous solution of Tween 60
2 ml 1,~ aqueous solution of Span 60
4 ml 1% agueous solution of Methocel A-15
Nitrogen was bu~bled through the aqueou8 8~ution Po~ 15 minukea.
The bottle was charged with 20 g liqui vi~yl c~loride,
0.044 ml (0.184 mmole) t-butyl peroxyoc~-oate ~0.2~ by waight o~
vinyl chloride) and 0.0165 g ~0~092 mmole3 c~-Dt~-glucose (dextro~e),
as described in Example I. A~ter 16 hours at 50C, the yteld of
poly(vinyl chloride) was 9.2 g (46~ conversiQn).
EX~PLE XI
The procedure of Example X was repeat~d u~ing the same
suspension recipe and reactants. In addition, 0.005 g (0.0092 mmole)
stannous laurate (glucose/stannous laurate mole ratio = 10/1) was
c arged to the reaction mixture. The yield of polymer wa~ 15.g g
(79.5% conversion) after 16 hours at S0 C.
- In addition to the monosaccharides which function a~
reductants in the practice of the present invention, the disaccharides
which are reducing sugar~ pex se, e.g. malto~e, lactose, cellobio~a
an~ gentiobiose, a~ well a~ disaccharides which rea~ily undexgo
hydrolysis to reducing monosaccharides in ~he aqueou~ environm~nt
used in suspension polymerization, e.g. sucro~e, may be u~ed in th~
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pra~tice of this invention~ although they are generally les~
ef~ective reductants than the mono~accharides. The carboxylic
acid esters o~ the disaccharides may also be used as reductants,
as illustrated by the use of sucrose octaacetate in Example IX.
While particular embodiments of this inv0ntion have
been disclosed above, i~ will be understood that the invention is
obviously subject to variation and modi~ication without departing
from its broader aspects.
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