Note: Descriptions are shown in the official language in which they were submitted.
82
The invention relates to a process for improvin~ the
properties o~ pulverulent vinyl chloride polymer~, in which the
polymer is sub~ected to heat treatment at 75 to 120a for 10
to approximately 360 minutes in the presence of an organic
aliphatic compound having 2 OH groups and 2 to 24 carbon atoms.
As a re~ult of recent investigations lnto damaging physiolo-
gical actions o~ monomeric vinyl chloride that may possibly occur,
it l~ desirable to obtain from this monomer polymers that have
a substantially lower content oi monomeric ~inyl chloride (VC)
than was customary h:Ltherto.
In the known indu~trial ma~ufacturing proces~es o~ polyvinyl
chloride and of it~ oopolymers and graft polymers with other mono-
mers or polymers, which contain a predominant proportion of poly-
merlsed vinyl chloride, at the end o~ the polymerisation process
and arter releasing the reaction mixture pressure a product is
obtained which contains up to 3 ~ by weight oi unreacted vinyl
~ ~ ohl~ride.
:~' ~ ' ' ' ' '
: ' . , 2 -
.- .- . - - : ,
~ 8 2
If the reaction products of the emulsion or the suspension
polymerisation are in the form of a dispersion o~ the polymer in
water, the residual monomer content can be reduced by treating
with steam or heated inert gases. Various processes are
known f,or this~ In some processes the aqueous dispersion is
intimately mixed with the steam simply be conveying the
two together in a tube or by spraying the dispersion in a steam
atmosphere and after a relatively short or long contact time,
this mixture, optionally with additional heating through the
container walls, is separated again into the gaseous phase
containing monomer and into an aqueous polymer dispersion having
a reduced monomer contentO It is also known to remove the
monomer content b~ pa~sing water vapor in countercurrent to the
aqueous polymer dispersion in a column or to treat the dispersion
with inert gas in a pipe evaporator.
It is ~urthermore known to remove residual monomer ~rom
aqueous dispersions o~ vinyl chloride polymers by vaporising
certain quantities o~ water for at least 15 minutes at 150 to 650
torr, In a ~urther known process slurrie~ or latices of ~inyl
chlorlde polymers are either heated to temperature~ o~ 70 to
125~ or brought into contact with at least one organic liquid
at bmperatures o~ 25 to 125C and the monomer removed ~rom the
slurrie~.
It i8 also known to remove residual monomers by treating with
steam moist vinyl chloride polymerisation product from
emulsion or suspension polymerisation.
' ' , .....
~' . ..
,
.
.
:: '
~, . . .
All these processes are concerned with mixtures of polymer
and water either in the form of aqueous dispersions, in which the
proportion of water is greater than the proportion of polymer,
or in the form of moist products, as produced by decanting aqueous
polymerisation products of suspension polymerisation a~d possessing,
- generally, a water content of 15 to 35 /~ by weight.
Some of the processes mentioned require considerable expen-
diture on apparatus. In the case of t~e short process (duration
of treatment a few seconds to a few minutes) the monomer removal
effect is generally inadequate. In so far as it concerns the
degassing of aqueous disparsions, difficulties may arise as a
result of foaming, either neces~itating additional expenditure on
apparatus or the addition of special agents which increase the
co~ts and may also influence the end product in an unde`sirable
manner. All of the processes mentioned require a relatively large
amount of energy since, in some cases, apart from the polymer,
considerable quantities o~ water must be heated or evaporated.
They are furthermore not very well suited to polymers that are
- produced without water, for example according to the buIk or gas
phase polymerisation proces~
To remove re~idual monomers ~rom dry vinyl chloride polymers,
namely those that have been obtained according to the bulk or gas
phase polymerisation prooess, a process is known in which water
vapor is ¢ondensed onto the dry polymers and, after this conden~ed
water has acted for some time, it is evaporated again by the action
o~ heat. As a result of the addition of water by means of condensa-
tion an important advantage of the so-called "dry" polymerisation pro-
cess, that is,-being able to dispense with ~eparating the water by
~iltration and/or drying, i~ lost. In addition, i~ is clear that onl~
~ 4 ~
. ~ . . . . . . . .
-~
.
.
- . : . .
polymers havin~ a residual monomer content of above 0.01 % by
weight of vinyl chloride can be produced according to this pro-
cess and these do not meet the recent ideas put forward for a
physiologically tolerable polyvinyl chloride (at most 0~001
by weight of residual vinyl chloride or less~.
A process has now been ~ound for reducing to a very low
level the residual contents of monomeric vinyl chloride in æubstan-
tially dry vinyl chloride polymers with~ut the above mentioned
disadvantages.
This is a process for improving the properties of homo-,
co- or gra~t polymers that contain at least 50 ~0 by weight of
polymerised vinyl chloride units, in which after removing the main
quantity o~ unreacted monomer or monomers and, if present, water,
the polymers, in a pulverulent ~tate and at atmospheric pressure
or reduced pressure, are subjected to a heat treatment,characterized
in that the heat treatment is carried out for 10 to approximately
360 minute~ at 75 to 120C in the pre~ence o~ 0.01 to 5 ~ by weight
(calculated on the polymer) of at least one aliphatic, ~aturated or
unsaturated, branched or unbranched aompound t~t contains 2 iree
hydroxyl groups and 2 to approx~mately 24 carbon atoms and that,
in the oase o~ 4 or more carbon atoms, may also contain at least
one C-0-C groupO
~ he removal of the main quantity of the unreacted monomer
or monomers is darried out according to known processes by relieving
the pressure o~ the polymeri~ation mixture. If the polymer has
been pr~oduced by bulk or gas phase polymerisation and is already
dry, it is generally subsequently evacuated. The vacuum is then
removed with inert gas. I~ the polymer has been produced in aqueo~s
~ 5 ~
: ' ~ , , '
- ~ ~ ~ . .: . ~ . . ..
- .. ...
82
.
~u~pension, after relieving the pressure of the polymerisation mix-
ture the sepa~ation of the water i~ carried out, ~or eY.ample, by
decanting and drying in an air current. In all case~ a pulverulent
polymer is obtained which generally still contain~ 1 to 0.1 ~ by
weight of residual monomer(s).
The subsequent heattreatment can be carried out under atmos-
pheric pressure or reduced pressure. It is advantageously carried
out at 50 to 760 torr, especially at atmospheric pressure. The heat
treatment is carried out for 10 to approximately 360 minutes at
temperatures o~ 75 to 120C. During the course of this one or more
inert gases such as air, nitrogen and steam ~or mixtures of
at least two of the gases air, nitroxen and steam are advanta-
geouslg passed through the ~essel in which the treatment ls carried
out. ~ir, especially i8 u~ed.
The concentration o~ the monomeric vinyl chloride in the polymer
decreases as the temperature and the duration of the treatment increase.
If the duration of the treatment is less than 10 minutes then the
re~idual monomer content achieved is generally not ~ufficiently low.
With higher temperatures and longer treatment time~ unde~irable dis-
colouring o~ the polymer increa~e~. Thi~ make~ polymer~ o~ this type
strlkingly unattractive, particularly in thermopla~tic processing,
because only moulded articles with discoloration~ can be produced.
In the ab~ence of compounds having 2 iree OH groups and 2 to appro-
ximately 24 carbon atoms, used in accordance with the in~ention, such
d1scolouration8 occur prematurely and, as a result, extensive removal
of the reeidual monomer is possible either only im~erfectly or only
by accepting undesired discoloration. If the heat treatment i~ carried
out in the pre~se~ce o~ the above mentioned compound~ it is
possible to increase the treatment time and temperature.
- 6 -
.,,~, . . .
18~
`, . :
Above 120C temperature and above ~60 minutes treatment time theprocess according to the invention offers no further advantages
in practice, since beyond these conditions the particle varia-
tions are too pronounced and discoloration occurs. Particularly
good results are obtained if the treatment is carried out at 80 to
100~ .
Advantageously the heat treatment is carried out in such a
manner that the product of treatment temperature (C) and treatment
time (hours) is 25 to 350 (a . h) and especially 50 to 260 (C 0 h)~
~he heat treatment is carried out in the presence of 0.01 -
to 5 ~ by weight (calculat~d on dry polymer) of at least one
aliphatic saturated or unsaturated, branched or unbranched compound
having 2 free hydroxyl ~roups and 2 to 24 carbon atoms, which in
the case of 4 or more carbon atoms may also contain at least one
C-0-C group.
Below 0.01 % by weight the aetion of the compounds i~ no longer
observed; above 5 ~o by weight addition, the disadv~ntages of such
'Sadaitions as a result of a deterioration in the pourability of the polym~r
~Fxx~ler, reduction m the thermal stability under load and transparency
of the moulded articles produced ~rom the polymer, as well as adhesion
to the part~ oi the pro¢e~sing machine, outwei~h the advantagesO
Advantageously, 0.2 to 2 ~ by weight and especially 0.5 to 1.5 ,'
by weight (calculated on dry polymer) are used.
~he sAid compounds may be added to the reaction mixture before
or during the polymerisation of the vinyl chloride or may be added,
after polymerisation, to the finished polymer before the heat treat-
mentO ~or the purpose of better distribution in the finished polymer
the compound~ may be added diluted with, or dissolved in, readily
....
volatile solvents, for example water.
~ 7 ~
~,. ~ . _ " .. ....... ~
- .
- :
.
Too ~re~t a dilution with water should be avoided, since
in the presence of relatively large amounts of water, commencing
at approximately 5 ~ by weight o~ water calculated on the dry
pol~ymer, the effect according to the invention decreases and
discoloration occurs increasingly the higher the quanti~y of
water.
The compounds to be used in accordance with -the invention
may contain C-0-C bonds, that is ether-oxygen bridges. Good
results are obtained with compounds of the formula
X
H0 (CH2 - CH ~ )n H
in which
X = H and/or CH~-
n = 1 to 12.
Diglycol or triglycol or a mixture o~ diglycol and triglycol
are especially suitable for the heat treatment according to the
invention.
Apart from these aliphatic saturated compounds with ether-
oxygen bridges good results are also obtained if the heat treatment
~s carried out in the ~resence of aliphatic, saturated or unsatursted,
branched or unbranched compounds having 2 free hydroxyl groups and
3 to 12 carbon atoms that do not contain ether-oxygen bridges.
- 8 -
. . ~ . .
` ' ' :-, ', , ' , . . . :
- ' ': : ' : .
- ~ ' ' , , . ' , ' ::
There may be mentioned as examples of such compounds: l,3-pro-
panediol; 1,4-butanediol; l,6-hexanediol; 1,5-pentanediol;
2,5-hexanediol; 1,10-decanediol. Particularly good results are
obtained with 2-butene-1,4-diol.
Of the subst~nces to be used in accordance with the invention
it is possible to employ one individually or mi~tures of several
of these substances.
The addition of these substances before or during polymerisa-
tion does not noticeably alter the quality or the rlatt~e of the
particles of the polymer produced; al~ substances that are advant-
ageously used and are cu~tomary in polymerisation may be used together
with the sub~tances to be used in accordance with the invention,
Dry vinyl chloride homo-, co- or graft polymers that contain
at least 50 % by weight of polymerised vinyl chloride units and
have been produced according to the emulsion or suspension polymeri-
sation process, are suitable for the treætment according to the inven-
tion, The polymers preferably used are those that have been produced
in the gas phase and especially those produced by bulk polymerisation
at temperatures of 30 to 85C. All the polymerisation processe~
mentioned may be carried out continuously or in batches
Vinyl chloride homo- or copolymers with a content of at least
80 ~ by weight (calculated on total polymer) of polymerised vinyl
chloride, especially homopolymers with a content of at least 98 70
by weight (calculated on total polymer) o~ polymerised vinyl chloride,
~re especiall~ suitable.
One or more of the following monomers are suitable for copoly-
merisation wit~ vinyl chloride, for example: olefins such as ethylene
or propylene; vinyl esters of s-traight-chained or branched carboxylic
:.
_,~9 _
.
- . . .:
.
" -' . ~ ~ ' ,
acids having 2 to 20, preferably 2 to 4 carbon atoms, such as
vinylacetate, vinylpropionate, vinylbutyrate, vinyl-2-ethylhexoate,
vinylisotridecanoic acid esters; vinyl halide~, such as vinyl
fluoride, vinylidene fluoride, virylidene chloride, vinyl ether,
vinyl pyridine; unsaturated acids, such as maleic, fumaric, acrylic,
and methacrylic acids and their mono or diesters with mono or dialco-
hols having 1 to 10 carbon atoms; maleic acid anhydride; maleic acid
imide and its N-substitution products with aromatic, cycloaliphatic
and optionally branched, aliphatic substituents; acrylonitrile and
styrene.
There may be used ~or gra~t polymerisation, for example,
elastomeric polymers that have been obtained by the polymerisation
of one or more o~ the ~ollowing monomers: dienes, such as butadiene
and cy¢lopentadiene; olefins, such as ethylene and propylene;
unsaturated acids, ~uch as acrylic or methacrylic acid and the
esters of such acids with mono or dialcohols having 1 to 10 carbon
atoms; styrene; acrylonitrile; vinyl compounds, such as vinyl esters
of straight-chained or branched carboxylic acids having 2 to 20,
pre~erably 2 to 4, carbon atoms; vinyl halides, such as vinyl
¢hloride and vinylidene ohloride.
~ he polymeri~ation can be carried out with or without a seed
polymer in the presence of 0.001 to ~ ~o by weight, preferably 0.01
to 0.3 % by weight, calculated on the monomers, of radical-forming
catalysts, such as, ~or example, diargl and diacyl peroxides, such
as diacetyl, acetylbenzoyl, dilauroyl, dibenzoyl, bis-2,4-dichloro-
benzoyl and bis-2-methylbenzoyl peroxides; dialkyl peroxides, such
88 di-tert.-butyl peroxidR; peresters, such as tert.-butyl percar-
bonate; tert.-butyl peracetate, tert.-butyl peroctanoate, tert.-butyl
perpivalate; dialkyl peroxidicarbonatesS such as diisopropyl,
: :
1 0 -
.
- , i ~ - . - . . .. ... -,
- ., . ~ , : . ~ ., ~ . . . .
-, . . , .
8Z
diethylhexyl, dicyclohex~l and ~iethylcyclohexyl peroxidicarbonates;
mixed anhydrides of organic sulfo peracids and organic acids, such
as acetylcyclohexylsulfonyl peroxide; azo compounds known as poly-
merisation catalysts, such as a~oisobutyric acid nitrile; for the
polymerisation using aqueous phases it is furthermore possible to
use in addition to the above mentioned catalysts, peroxydisulfates,
peroxydiphosphates, or perborates of potassiumJ sodium or ammonium,
hydrogen peroxide, tert.-butyl hydroperoxide or other water-soluble
peroxidesS as well as mixtures of various catalysts, wherein peroxlde
catalysts may be used also in the presence o~ 0.01 to 1 ~ by weight,
calculated on the monomers, of one or more reducing sub~tances that
are suitable for making up a redox catalyst system, such as, ~or
example, sulfites, bisulfites, dithionites, thiosulfates, al~ehyde
sulfoxylate such as, for example, sodium formaldehyde sulfoxy-
late. Optionally, the polymerisation may be carried out in
the presence of 0.05 to 10 parts of metal per million parts of
monomer, of readily 3eluble or sparingly soluble metal salts, for
example, of copper, silver, iron or chromium.
Molecular weight regulators may be added be~ore or durinæ
polymer;isation: such a~, ~or example, aliphatic aldehydes having
2 to 4 carbon atoms, chlorohydrocarbons or bromohydrocarbons such
a~, for example, dichloroethylene and trichloroethylene, chlorofcr~t
bromoform, methylene chloride and mercaptans; also other polymerisa-
tion au2iliarie~Q, such as anitoxidants, for example, 2,6-di-tert.-
butyl-4-methylphenol , trisnonylphenyl phosphite, other additives,
such as epoxidised oils, for example, soya bean oil; fatty alcohols
or fatty acid esters or au2iliaries for further processing of the
polymer, such as, for example, known lubricants, waxes, heat and
light stabilizers, plasticizers and pigments. The last-mentioned
'
, .' ',, . ~ .:
-
.
- ~ '. ~ ,', ' . ~ '
82
.
auxiliaries for further processing may alternatively be added at
the end of the polymerisation process, optionally in a dissolved,
molten or dispersed state.
If polymerisation is carried out using an aqueous liquor,
this may contain 0.01 to 1 5~ by weight, preferably 0.05 to 0.3 5
by weight, calculated on the monomers, of one or more protective
-colloids such as, for example, polyvinyl alcohol optionally containing - --
_ _ .. . . . .. . . . . . . .. .. . .. . . . . . . . . . . . . . . . .. . . .. . . .
up to 70 mole % of acetyl groups; cellulose derivatives,
such as water-soluble methyl cellulose, carboxymethyl cellulose,
hydroxyethyl cellulose, mixed cellulose ~hers, for example
methylhydroxypropyl cellulose; as well as gelatin, and also co-
polymers of maleic acid or the semi-esters thereof and styrenes.
Polymerisation in a(lueous liquor can furthermore be carried
out in the presence of 0.01 to 5 ~o by weight, calculated on the
monomers, of one or more emulsifiers, wherein the emulsifiers are
- introduced in admixture with the above-mentioned protective colloid.s.
It is possible to use anionic, amphoteric, cationic and non-ionic
emulsifiers. Suitahle anionic emul~ifiers are, for example,
alkali.metal salts, a~kaline ea~th metal salts and amm~nium salts of fatty
ZO acids, such as lauric acid, palrnitic acid or steario aoid, of acid
fatty alcohol sulfuric acid esters, of paraffinsu.lfo acids, of
alkylarylsulfo acids, such as dodecylbenzenes~fo acid or dibutyl-
naphthalenesulfo acid, of sulfosuccinic acid dialkyl ester~, and
the alkali r~tal and amnoniurnsalts of epoxy group-containLng fatty acids,
such as epoxystearic acid, of reaction products of peracids, for
example, peracetic acid with unsaturated fatty acids, such as oleic
acid or linoleic acid, or unsaturated hydroxy fatty acids, such as
ricinoleic acid. Suitable amphoteric or cation-active emulsifiers
are, for example: alkyl betaines, such as dodecyl betaine and
- 12 -
' ' .
: - : . . .- . .
.. . . : . . ~ , . . .
- , ~ . . .. . .
- : ~ . . - - ~
alkylpyridinium salts, such as hydroxyethyldodecylammonium chloride.
Suitable non-ionic emulsifiers are, for example: partial fatty acid
esters of polyhydric alcohols, such as glycerylmonostearate, sorbitol
monolaurate, oleate or palmitate, polyoxyethylene ethers of fatty
alcohols or aro~atic hydro~y compounds; polyoxyethylene esters o~
fatty acids as well as polypropylene oxide-, polyethylene oxide
condensation products.
After polymerisation there ~y be added to the polymers produced
other substances, such as, for example, the processing auxiliaries
mentioned above for stabilising and improvi~g the properties of the
polymers for further proce~sing, optionally before or after separa~
ting the aqueous liquor.
For the treatment according to the invention the vinyl chloride
polgmers may contai.n up to 20 % by weight, calculated on the total
substance, of compounds that do not consist o~ polymerised vinyl
chloride. Such compounds may, ~or exa~ple, be monomeric vinyl .
ch~oride as well as other monomers used for polymerisation, poly-
merisation auxiliaries as well as, optionally, further processing
auxiliaries; for example, those mentioned above; poly~er~ not
containin~ vinyl chloride, such a~ impact stren~th modifier~,
polymeric additives ~or improving the flow properties and processing
properties and/or thermal stability under load and pigments.
~ he heat treatment is carried out in the presence o~ one or
more inert gases such as, ~or example, a1r, nitrogen or
steam.
During this heat treatment it is advantageous to move the
polymer powder and/or the gas phase in order to achieve intensive
.
- 13 - . .
. .
.
-
Z
contact o~ the two phase3 with one another. Mechanical
~r pneumatic means are suitable for this,
for example, stirring, causing turbulence in ~he po~der, allowing
the powder totrickle down or spraying the powder in the gas chamber,
wherein an additional relative speed with respect to the solid
particles may optionally be given to the gas, for example in such
a manner that the gas flows through a more or less loosened-up
layer of po~tder, preferably upwards from below.
The treatment according to the invention may advantageously
be carried out in the polymerisation ve~sel after removing the
main quantity of liquid or gaseous reactants, or in one or more
devices, connected in series, for example, a down pipe or flow
pipe, a high-speed mixer, a revolving tube advantageously provided
on the inaide with scoops, or a cyclone, it being possible for both
the gas and the polymer to be circu~ated. Advantageously a device
is used in which the polymer is guided, in a rotationaily ~~
symmetric container in several flow rings arranged one above
the other, by means of-the tangential introduction of gas using
; appropriate fittings, or a fluidised bed or vortex bed is used.
The process according to the invention makes it possible to
subject vinyl chloride polymers, and especially those that have
been produced at ~0 to 85C according to the bulk polymerisation
pro¢ess, to an intensive temperature treatment as is necessary to
remove harm~ul re~sidual monomers, for example, vinyl chloride, without
havir~ to euffer marked discoloration of the material impairing its
further use, The tre~ted polymers, contrary to thosenot treated, do
not exhibit any impairment of the properties important for processing
and use. The process may be carried out continuously and is not very
liable to failure.
. .,.................................................... '~
.
,
~.. , . ~,.,......... ~ .. . .. , -
',, ~ ' . . - ' :
, . . . - . ~ . : -. . : .
- - - . ,
- .. - . : -
:
182
The temperature can optionally be adjusted to the desired
treatment ef~ect, thereby guaranteeing an intensive but careful
treatment. The necessary devices are relatively simply built,
sturdy and require little space for construction. In particular,
the treatment of the polymer in thePlYmeriZatin vessel necessitates
only very low investment costs.
The ~ollowing examples are intended to illustrate the
invention in detail. The results of measurements listed therein
were determined as ~ollows:
K value:
According to DIN 53 726, solvent: cyclohexanone.
VC r~esidual monomer content:
Determined by gas chromatography according to the "head-space"
method (Zeitschrift f~r Analytische Chemie, 255 (1971) pages 345
to 350).
Discoloration test-
. .
Polymer 100 part~
Di-n-octyltin-bis-thioacetic acid
ethylhexyl ester 1.5 parts
2 ~ ~ubricant mixture, consistin~ of hyclro~enated
D ca3tor oil, triglyceride and monoglyceride,
(obtainable under the name ~oxiol~G~ 4) 007 parts
Montanic acid ester of 1,3-butanediol 0~3 parts
Deno ~ /rade ~k
~ 15-
, . .
:, .
; ' ' ' . .
.... .. ., .. ~, - .. . . ~ . .
..
-
L18Z
.
The components are thoroughly Mixed mechanically without
heating and 300 grams of the mixture are plasticized for three
minutes on a laboratory rolling mill with two rollers, whilst
applying heat, to form a 3 mm thick rolled sheet.
,
Technical data:
~oller diameter 150 mm
~peed of rollers 11 revs~min
Roller temperature ~75C
A~ter coolin~ the rolled sheet, rectangular portions o~
10 10 x 12 cm are cut out of the sheet, 12 of these portions are
: placed into a compression mould with internal dimensions of
11 x 12.5 cm, which is arranged in a plate press heated to 175C.
The rolled sheet portions are pre-heated under slight pressure ~or
3.5 minutes then, ~or a period of ~ minute, the full pressure of
40 ~ cm2 is applied, after a further 4 minutes cooling is effected
with water under pressure to room temperature, the pressure is
relaxed, the pressed plate i8 removed from the rnould and obs~r~i.ng
the edge o~ the plate against a uniforr~y light, neutral white
background, the color number i8 visuallg determined in accordance
with a 5 part notation scale:
.
Not~tion 1:
Color as standard (usually faintly yellowish)
.
. Slightly discolored (yellowish)
~ ~ .
, , ''1: ` ' . ;'
-- 16 -- -
: ,
. ~ , -, : .
. ,
~: . . ., : - -
.~ .. . . ~ . . . ~ . . ..
- . . ..
Notation 3:
Clearly discolored (strong yellow color or reddish yellow)
. Notation 4:
Strongly discolored ( brown-yellow to orange-yellow)
Notation 5~
Very strongly discolored (light brown or orange red).
The standard used was a vinyl chloride homopolymer produced
according to the bulk process havin~ a K-value of ~7, as yielded
by polymerisation without subseauent heat treatment o~ the polymer
and having a residual vinyl chloride content o~ 1 /0 by weight
(calculated on the polymer).
BxamPle 1,~.
100 grams of diglycol and 500 grams of water are mixed in a
I high-speed mixer for ~ minutes with 10 kg of a vinyl chloride
; 15 homopolymer, produced by bulk polymerisation at 69C, having a
~-value of 57 and a residual vinyl chloride content of l % by
weight (calculated on the polymer), and then the mixture i~ treated
ior 3 hours at 85C in a circulating air dryin~ chamber and sub-
sequently cooled. At the end of the heat treatment 10C93 gram~
of polymer are obtained.
A flample of the powder yielded by the heat treatment was
dissolved in tetrah,ydro~uran, ~ubJected to a silylation reaction
with bis-trimeth,ylsilyl-trifluoroacetamide analogously to the
method described in the book by Allan E. Pierce l'Silylation o~
organic compounds'!, Publisher~: Pierce Chemical Comp~, Rockford/Ill,
.
- 17 - . .
: - . :
' ' ,
- .
~1118;2
U.S.A., 1968, pa~e 72 et sea.; the polymer was then precipitated
from the solution with methanol and the tetrah,ydrofuran-methanol
mixture examined by gas chromatography, A silylation product
of the diglycol could not be detected.
The determination o~ the residual vinyl chloride (V~)-content
is carried out by gas chromat`ography according to the "head-space"
method (see above) at 7 parts per 1 million parts (=PPM) of dry
polymer. The discoloration test resulted in the notation 1.5.
For the purpose of better comparison the values determined
are listed in the following table.
ComPa~rison exPeriment A~
The procedure is as in Example 1, using the same bulk
polymer but with the difference that the diglycol-water mixture
is not added. The values determined are listed in the following
~5 table.
a~ c,~ _ ent B:
The prooedure is as in Bxample 1, u~ing the same bulk polymer,
but with the difference that only 500 grams o~ water, without
digly¢ol, are added to lO kg of polymer.
. .
~20 Compari30n ex~eriment ~: ,
The procedure is as in Example 1, usin~ the same bulk polymer,
but with the difference that instead of the mixture of diglycol
and water, a mixture of 100 grams of phenol and 500 grams of water
is added to lO kg of polymer. The values determined are listed
in the following tableO
- 18 _
.
- . ., - . . .. : : ..
:: . : ., . : :
:~ .: . : : . . .
182
Example 2:
.,
A bulk polymer of vinyl chloride is produced according to
the 2-stage seed technique, wherein before the main polymerisation
(second stage) 1 % by weight (calculated on the total amount of
vinyl chloride used in both stages) o~ diglycol is added to the
reaction mixture and polymerisation is then ef~ected at 6ZC.
The main quantity of the excess, unreacted vinyl chlori.de is
removed from the polymer produced by evacuating three time~ to
approximately 50 torr. A~ter this treatment the po~y~er still
contains 0.2 ~ by weight of monome,ric vinyl chloride and has a
K-value of 60. 10 kg of the polymer thus produ.ced are then treated
for 300 minutes at 85C under normal pressure in a circulati~g
air drying chamber, and subsequently cboled. ~he vall1es measured .
are listed in the followine table.
. 15 Exam~ples~-5
.are carried out as in Example 1, but varying quantities of diglycol-
: water mixture are added to the polymer.
in Example 3:400 grc~m~ o~ dielycol and 1000 gra~s
of water
in ~x~mple 4:10 grams o~ diglycol and 100 grams
of water
in ~xample 5:5 grams of diglycol and 100 ~rams
of ~ater.
'i x~m~, ,
100 grams of 1,6-hexanediol c~nd 500 grams of water are mixed
for 3 minutes in a high-speed mixer with 10 kg of a vinyl chloride
homopolymer produced by bulk polymerisation at 55C having a E-value
.
- 19 _
:
- : - .. ' . .
1~ 8;2
of 67 and a residual vin~l chloride content of 0.3 5D by weight
(calculated on the dry polymer), and the mixture is then treated
for 50 minutes at 92C in a circulating air drying chamber and
subsequently cooled. The values measured are listed in the
following table.
Example 7:
A mixture of 100 grams 2-butene-1,4-diol and 500 grams of
water is added to 10 kg of a vinyl chloride homopolymer produced
by bulk pol,ymerisation at 62~ having a K-v~lue o~ 60 and a
residual vinyl chloride content o~ 0.2 ~o by weight (calculated on
; the dry polymer).
In a pressure-tight cylindrical vessel of 40 liters
capacity having an oil-heated dol~ble jacket and an anchor
mixer scraping along the wall, of which the mixer blades, curved
~15 in the shape of screws, are approximately 5 cm wide, brush the
entire base and approximately 80 % of the side walls of the vessel
and rotate at 60 rev/min, the polymer to which the above-described
mixture has been added is treated for 90 minutes at a pressure of
250 torr. The temperature of the heating oil is 92 C, the tempera-
,,20 ture of the polymer is measured at 85 C. During the treatment a
, weak air current is passed through the vessel.
; After 90 minutes, the reduced pressure is removed and coolin~
' i8 ef~ected. The values measured are listed in the following table.
,
Exa,mPle 8:
~25 In the same apparatus as i8 described in Example 7, a mixture
o~ 200 grams of 1~1o-decanediDl and 500 grams of ethanol is added to
10 kg of a vinyl chlorlde homopolymer produced by bulk polymerisation
'
- 20 -
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.
at 69a, and the mixture is treated for 120 minutes at a product
temperature of 97C, a pressure of 100 torr and a stirrer speed
of 60 rev/min whilst passing through a wealc air current, then
the reduced pressure is removed and cooling is carried out. The
values measured are listed in the following table.
~xample 9:
A mixture of 200 grams of a polyglyool of the average formula
HO(CH2CH20)11H and 500 grams of water is added to 10 kg of a vinyl
chloride homopolymer produced by bu~k polymerisation at 62C, having
a K-value of 60 and a residual vinyl chloride content of 0.2 5o by
weight (calculated on dry polymer), the mixture is mixed for 3
minutes in a high-speed mixer, then treated for 280 minutes at 75C
in a circulating air drying chamber and subsequently cooled. The
values measured are listed in the following table.
~E~am~le lO:
:; . .
The procedure is as in Example 1, using the same polymer, but
instead o~ diglycol-water, a mixture of 50 grams o~ 1,3-propanediol
and 500 grams of water is added. The heat treatment at 85C is
only 120 minutes long. The value~ measured are listed in the
~ollowin~ table.
Exam le ~11i
:~ .
The prooedure is as in ~xample 8, using the same polymer, but
j~ instead o~ decanediol-ethanol, a mixture of lO0 grams of 1,4-butanediol
and 500 grams of water ls addedO The heat treatment is ef~ected at a
product temperature of 90C. The values measured are iisted in the
following table. ~-
,',i ~ ' '
~ -21-
. . . ... .. . . . , ~ , . , ~ .:
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`
, : .
Exam~le 12:
The procedure 1s as in Example 1, using the same polymer,
except that instead of diglycol-water, a mixture of.200 grams
o~ neopentylglycol and 500 grams of water is added. ~he values
measured are listed in the following table.
':
In the table:
. .
VC. - vinyl chloride
min - minutes
PPM = parts per 1 million parts
of dry pol~Ymer.
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