Process for the production of paste-forming vinyl chloride polymers

Paste-forming polymers of vinyl chloride are produced by discontinuous polymerization in the presence of a conventional predispersion of emulsifier, dispersion acid, water and optional monomer-soluble catalyst. The predispersion is prepared only with 30-80% by weight of the amount of emulsifier required in total. The remainder of the emulsifier, or a component forming the emulsifier, is added in metered amounts as an aqueous solution batchwise or continously to the polymerization mixture after a conversion of 10-60% by weight. The thus-obtained polymers lead to pastes of an especially low viscosity, even under high shear stress, and result in open-cell plasticized foam materials having a good elastic memory capacity.

BACKGROUND OF THE INVENTION 
Continuous as well as discontinuous methods are known for the production of 
paste-grade polyvinyl chloride. The vinyl chloride polymer produced by the 
continuous process results in plastisols having low viscosities at high 
shear rates. However, greater amounts of emulsifier are needed for their 
production, leading to reduced transparency and higher water sensitivity. 
The vinyl chloride polymers normally obtained by continuous polymerization 
below the vinyl chloride saturation pressure are also inferior to the 
discontinuously polymerized polyvinyl chloride in regard to 
thermostability. 
The types of polyvinyl chloride produced by the dicontinuous method can be 
polymerized by emulsion polymerization with markedly lower quantities of 
emulsifier, especially if the emulsifier is added in accordance with the 
method of German Patent 1,964,029 or according to the laid-open disclosure 
of Belgian Patent 656,985. However, in all cases, plastisols are obtained 
having viscosities that are higher than in continuous polymerization. 
Also conventional is vinyl chloride polymerization according to the 
so-called microsuspension process. Plastisols from vinyl chloride polymers 
prepared by this process exhibit a pronouncedly dilatant behavior and thus 
are less suitable for being processed by the spread coating method. 
Besides, stable latices can be prepared only up to a solids content of 
about 40% by weight, which increases the spray-drying costs. 
Various discontinuous methods have been known for vinyl chloride 
polymerization with the use of dispersing aids, in most cases fatty 
alcohols. The following can be cited as state of the art: 
1. DOS 2,850,105 
2. DOS 2,742,178 (U.S. Pat. No. 4,093,581) 
3. European Patent 0,030,524 
4. German Application P 32 10 891.5 (U.S. application Ser. No. 478,766 of 
Mar. 25, 1983) 
5. German Application P 32 42 088.9 (U.S. application No. 551,033 of Nov. 
14, 1983) 
Polymerization according to method 1 is conducted by means of oil-soluble 
activators, partially with the addition of reducing agents. This process 
leads to products which, when processed into plastisols, exhibit a 
strongly dilatant flow characteristic, as can be seen from Comparative 
Experiment A of German Patent Application P 32 10 891.5. 
The process described in (2) utilizes inorganic catalysts for the 
activation. Accordingly, a mixture is employed during polymerization 
consisting of a C.sub.16 -C.sub.20 -alkyl alcohol and an alkyl sulfate 
(C.sub.12 -C.sub.18). As demonstrated by Comparative Experiments B and C 
of German Patent Application P 32 10 891.5, latices are obtained according 
to (2) which are either unstable or of a low solids content, yielding a 
polyvinyl chloride upon spray-drying which results in high-viscosity 
pastes with a pronounced pseudo-plastic flow behavior. 
According to (3), a water-soluble material is first homogenized in the 
presence of water and emulsifier. Thereafter, the monomer and initiator 
are added thereto. In order to conduct the process successfully, the 
presence of a seed latex (stabilizing latex) is required, and thus the 
process is comparatively expensive. 
According to (4), though low-viscosity pastes are obtained, increased 
technical expenditure is required. This is so because the predispersion to 
be added during polymerization must be prepared in a separate, heatable 
agitated vessel and must be heated throughout the entire polymerization 
procedure to above the melting point of the fatty alcohol employed. In 
spite of the heated action, the predispersions may change during the 
period of metered feeding outside of the vessel, leading to fluctuating 
product properties. Additionally, when processing the products prepared 
according to (4) into expandable plastisols with the use of chemical 
blowing agents, such as, for example, azodicarbonamide, foam materials are 
obtained after gelling which have a primarily closed-cell foam structure. 
This, as is known, results in foams having a lack of elastic memory 
capacity. 
The process listed in (5) likewise requires increased technical 
expenditure, since a pressure homogenizer is utilized. 
SUMMARY OF THE INVENTION 
These objects have been achieved by a process for the production of 
paste-forming polymers of vinyl chloride, or mixtures of vinyl chloride 
with up to 30% by weight of copolymerizable monomers, by discontinuous 
polymerization in the presence of water-soluble or monomer-soluble 
catalysts and a predispersion of 
(a) an alkali metal salt or ammonium salt of a branched or unbranched fatty 
acid containing 12-18 carbon atoms, of a branched or unbranched 
alkylsulfonic acid containing 10-20 carbon atoms, of an alkylarylsulfonic 
acid containing 8-18 carbon atoms in the branched or unbranched alkyl 
chain, or of a sulfosuccinic acid ester containing 6-14 carbon atoms in 
the alcohol portion, in amounts of 0.2-3.0% by weight, based on the 
monomer, 
(b) a straight-chain or branched C.sub.12 -C.sub.20 -alkanol in amounts of 
50-200% by weight, based on the tenside employed, 
(c) water, as well as optionally 
(d) a monomer-soluble catalyst, wherein the predispersion is prepared only 
with 30-80% by weight of the amount of emulsifier (a) (amount of tenside) 
required in total, and is added to the polymerization batch, whereas the 
remainder of the emulsifier, or of a component forming the emulsifier, is 
added in metered quantities batchwise or continuously as an aqueous 
solution to the polymerization mixture after a conversion of 10-60% of 
weight. Preferably, only 40-60% by weight of the amount of emulsifier 
required in total is utilized for preparing the predispersion. In 
particular, the remainder off the emulsifier can be added after a 
conversion of 20-60% by weight. 
DETAILED DISCUSSION 
The thus-obtained polymers of vinyl chloride can be utilized advantageously 
for the production of plasticized foam materials with the use of chemical 
blowing agents, since this will result in foam materials with a 
predominantly open-cell structure; as is known, such materials exhibit a 
good elastic memory capacity. 
The polymers produced according to the process of this invention are 
especially suitable for the preparation of plastisols having a very low 
viscosity under low as well as high shear gradients. This affords high 
processing speeds when the plastisols are processed according to the 
spread coating process. Besides, the plastisols exhibit a very good shelf 
stability if the vinyl chloride polymers of this invention are employed. 
In the production of foam materials from corresponding plastisols and with 
the use of chemical blowing agents, predominantly open-cell foams having 
good elasticity and a good elastic memory capacity are obtained when using 
the vinyl chloride polymers of this invention. 
It is surprising that, with the use of a predispersion with a markedly 
reduced amount of emulsifier and the addition of an aqueous emulsifier 
solution during polymerization, a stable dispersion results which leads to 
products of low paste viscosity. It has also been found suprisingly that 
chemically foamable pastes produced therefrom resulted in foam materials 
having an open-cell foam structure; as is known, these foam materials 
exhibit a very good elastic memory capacity. 
It makes no difference whether the emulsifier in the emulsifier solution is 
added as such, or is released in situ. For example, if fatty acid salts 
are utilized as emulsifiers for the preparation of the predispersions, 
then it is possible according to the process of this invention to provide 
the entire fatty acid during preparation of the predispersion, but to 
provide only a part (i.e., 30-80%) of the stoichiometrically required 
amount of alkaline solution for the formation of the emulsifier. By the 
corresponding addition of the aqueous solution of a base, for example 
NaOH, KOH, ammonia, etc., during polymerization, the emulsifier can be 
released in the manner of a subsequent feeding of emulsifier. In this way, 
the expensive handling of fatty acid salt solutions can likewise be 
avoided. Analogous expedients can be employed in conjunction with the 
other emulsifiers. 
The vinyl chloride polymers produced according to this process of the 
invention lead to pastes having very low paste viscosity. 
The predispersion of water, co-emulsifier (b), and a partial amount of 
emulsifier (a) can be prepared directly in the polymerization reactor 
according to the method of this invention. In this way, additional, 
heatable agitated vessels as well as heatable metering vessels and 
metering conduits are eliminated. There is no danger of an alteration of 
the predispersion outside of the polymerization reactor, since the only 
materials added during polymerization are the tenside and/or the alkaline 
solution, which can be added in metered quantities without any problems. 
Emulsifier sytems that can be employed include: 
(a) alkali metal salts or ammonium salts of fatty acids, of alkylsulfonic 
acids or alkylarylsulfonic acids or sulfosuccinic acid esters in 
quantities of 0.2-3% by weight, preferably 0.5-1.5% by weight, based on 
the monomer, and 
(b) a straight-chain or also branched C.sub.12 -C.sub.20 -alkyl alcohol or 
mixture of several such alcohols in amounts of 50-200% by weight, 
preferably 70-150% by weight, based on the tenside (a) employed. 
Suitable alkali salts or ammonium salts of fatty acids utilizable as the 
emulsifier component (tenside) include those, wherein the alkyl chain 
contains 12-18 carbon atoms and which are branched or unbranched. The 
following can be used, for example: sodium laurate, sodium myristate, 
sodium palmitate, sodium isopalmitate, sodium stearate, etc. The 
corresponding potassium and ammonium salts are likewise suitable. 
Alkali metal salts or ammonium salts of alkylsulfonic acids that can be 
employed as the emulsifier component include those wherein the alkyl 
residues contain 10-20 carbon atoms, preferably 14-17 carbon atoms, and 
which are branched or unbranched. Examples of suitable compounds include: 
sodium decyl sulfonate, sodium dodecyl sulfonate, sodium palmityl 
sulfonate, sodium stearyl sulfonate, sodium heptadecyl sulfonate, sodium 
arachidyl sulfonate, etc. The potassium or ammonium salts can likewise be 
used with analogous success. In general, mixtures of the aforementioned 
individual compounds will be preferred, as they are obtained in the 
sulfonation of industrial alkane mixtures. 
Suitable alkali metal or ammonium salts of alkylarylsulfonic acids which 
are to be used as the emulsifier component are those wherein the alkyl 
chain contains 8-18 carbon atoms, preferably 10-13 carbon atoms, this 
chain being branched or unbranched. Examples include: sodium 
tetrapropylenebenzenesulfonate, sodium-p-n-dodecylbenzenesulfonate, sodium 
octadecylbenzenesulfonate, sodium octylbenzenesulfonate, sodium 
decylbenzenesulfonate, sodium tridecylbenzenesulfonate, sodium 
tetradecylbenzenesulfonate, sodium pentadecylbenzenesulfonate, sodium 
hexadecylbenzenesulfonate, etc. Preferably, mixtures of such individual 
compounds are employed. It is also possible to use the potassium salts or 
ammonium salts. 
Suitable alkali metals or ammonium salts of sulfosuccinic acid esters 
useful as the emulsifier component are those wherein the alcohol portion 
contains 6-14 carbon atoms, preferably 8-10 carbon atoms, and is branched 
or unbranched. Suitable examples include: sodium dihexylsulfosuccinate, 
sodium dioctyl sulfosuccinate, sodium di(2-ethylhexyl) sulfosuccinate, 
sodium didecyl sulfosuccinate, sodium didodecyl sulfosuccinate, sodium 
diisodecyl sulfosuccinate, sodium diisododecyl sulfosuccinate, sodium 
tridecyl sulfosuccinate, sodium ditetradecyl sulfosuccinate, etc., and the 
corresponding potassium and ammonium salts. It is also possible to use 
mixtures of the aforementioned emulsifiers. These emulsifiers generally 
have the formula 
##STR1## 
wherein R and R.sup.1 are each C.sub.6-14 -alkyl; and M is ammonium or an 
alkali metal. 
Mixtures of the four general classes of emulsifiers can also be used. 
Suitable dispersion aids include straight-chain or branched C.sub.12 
-C.sub.20 -alcohols, such as, for example, lauryl alcohol, myristyl 
alcohol, palmityl alcohol, stearyl alcohol, arachidyl alcohol, 
2-hexyldecanol, 2-octyldecanol, etc. Mixtures of the above-listed alcohols 
can also be employed. 
Components (a) and (b) of the emulsifier system should be dissolved or 
dispersed in water. If a monomer-soluble initiator is chosen for the 
polymerization, such initiator likewise can be added to the mixture. In 
case the melting points of the fatty alcohols lie above room temperature, 
the dispersion step is advantageously conducted at temperatures of 
30.degree.-70.degree. C., i.e., above the melting temperature of the fatty 
alcohols. 
In the selection of a suitable monomer-soluble initiator, attention must be 
given to preventing any marked decomposition of the initiator as early as 
during the dispersion step. Those initiators are employed with preference 
which, at the required dispersing temperature, exhibit half-life values of 
higher than 10 hours, preferably higher than 20 hours. If an initiator 
having a high half-life value is selected on account of the high melting 
point of a fatty alcohol employed, then the subsequent polymerization 
reaction should be controlled by means of suitable reducing agents. See 
also, e.g., the monograph of Kainer, Polyvinylchlorid und 
Vinylchlorid-Mischpolymerisate, Springer Verlag, Berlin, Heidelberg, N.Y., 
(1965), p. 46-49. 
Except for the quantities of water required for the metered feeding of the 
emulsifier and possibly the activator, as well as reducing agents, the 
entire amount of the water needed for the polymerization can be charged 
into the reactor during preparation of the predispersion. Conventional 
buffer salts can be added to the water, such as, for example, sodium 
pyrophosphate, sodium acetate, or sodium borate. 
After producing the predispersion, vinyl chloride or a mixture of vinyl 
chloride and copolymerizable monomers is added under agitation. After 
setting of the desired polymerization temperature, the polymerization 
reaction is started by means of the selected initiator system, and 
controlled by the latter. It is especially advantageous regarding latex 
stability to provide only 40-60% by weight of the total amount of 
emulsifiers when preparing the predispersion, and to add the corresponding 
remaining quantity as an aqueous emulsifier solution in metered amounts, 
batchwise or continuously starting with a polymerization conversion rate 
of 10-60%, preferably 20-60%, up to the end of the polymerization. The 
technically simplest method is the linear addition of the emulsifier 
solution throughout the remaining time of polymerization. However, 
dependent on the amount of emulsifier initially added and dependent on the 
conversion at the start of addition of emulsifier, it may be advantageous 
to choose the addition rate of emulsifier solution relative to the 
conversion, where the addition rate may increase or decrease with 
conversion. 
It is also possible to provide only a portion of the monomer and to add the 
remainder during polymerization batchwise or continuously. Comonomers that 
can be used are entirely conventional, for example: vinyl acetate, 
vinylidene chloride, vinyl ether, acrylonitrile, acrylic acid esters, 
maleic acid mono- and diesters. The comonomer can be present in the 
copolymerized product to an extent of up to 30% by weight, preferably 1 to 
20% by weight. 
The ratio of monomers to water can be arbitrary, up to very high vinyl 
chloride concentrations (about 1:0.5 to 1:1.6). In general, it will be 
desirable to conduct the polymerization so that latices are obtained 
having a maximally high solids content of, for example, 45-50% by weight. 
The final conversion, of course, should be as high as possible, and should 
amount to at least 90%. 
Suitable water-soluble catalysts include the customary percompounds, such 
as, H.sub.2 O.sub.2, potassium persulfuate, as well as the redox systems, 
as indicated, for example in Kainer, "Polyvinylchlorid und 
Vinylchlorid-Mischpolymerisate" [Polyvinyl Chloride and Vinyl Chloride 
Copolymers], Springer Publishers, 1965, pp. 46 et seq. 
Furthermore, considering the respective dispersing and homogenizing 
temperature, monomer-soluble initiators and--if necessary--the reducing 
agents usually employed for a redox reaction can be utilized. Examples of 
monomer-soluble initiators include azo compounds, such as 
azobisisobutyronitrile, 2,2'-axobis(2,4-dimethylvaleronitrile); or 
peroxides, such as dicyclohexyl peroxydicarbonate, di-n-butyl 
peroxydicarbonate, dilauroyl peroxide, debenzoyl peroxide, dipropionyl 
peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxybenzoate, 
cumyl hydroperoxide, tert-butyl hydroperoxide. Examples of reducing agents 
include sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbic 
acid, and isoascorbic acid. 
The initiators can be used in customary quantities of 0.005-0.5% by weight, 
preferably 0.01-0.1% by weight, based on the monomer. 
The polymerization temperature can be 40.degree.-70.degree. 
C.--conventionally depending on the desired molecular weight. The duration 
of polymerization is dependent--as in all cases--on the polymerizing 
temperature and the catalyst concentration and can amount to about 4-16 
hours. Suitably, the agitation should be carried out with the usual 
peripheral velocities of 10-70 rpm and by means of the flat-blade 
agitators customarily employed in emulsion and/or microsuspension 
polymerization processes. 
Unless indicated otherwise herein, all the details of the process of this 
invention are fully conventional, e.g., as disclosed in Ullmanns 
Encyclopaedie der technischen Chemie, Vol. 19, Verlag Chemie, Weinheim, 
Deerfield Beach (Fla.), Basel, page 346, et seq., whose disclosure is 
incorporated by references herein. 
Without further elaboration, it is believed that one skilled in the art 
can, using the preceding description, utilize the present invention to its 
fullest extent. The following prefered specific embodiments are, 
therefore, to be construed as merely illustrative, and not limitative of 
the remainder of the disclosure in any way whatsoever. In the following 
examples, all temperatures are set forth uncorrected in degrees Celsius; 
unless otherwise indicated, all parts and percentages are by weight.

EXAMPLE 1 
A 6 m.sup.3 agitated autoclave is charged with 1,600 kg of demineralized 
water of a temperature of 60.degree. C. Under agitation, 11 kg of sodium 
alkylbenzenesulfonate (mixtures of C.sub.10 -C.sub.13 
-alkylbenzenesulfonates), 22 kg of stearyl alcohol, as well as 3.7 kg of 
monosodium phosphate are added thereto. After exclusion of atmospheric 
oxygen, 1,800 kg of vinyl chloride is added. The mixture is set at 
52.degree. C., the agitator speed is adjusted to 10 rpm. By the metered 
feeding of a 0.5% aqueous H.sub.2 O.sub.2 solution and a 0.2% aqueous 
ascorbic acid solution, the reaction is started up. The further metering 
of the catalyst components is set so that the polymerization temperature 
of 52.degree. C. remains constant at almost full cooling capacity (jacket: 
600,000 kJ/h; reflux condenser: 120,000 kJ/h). One hour after startup of 
the reaction, 48 kg of a 20% aqueous solution of sodium 
alkylbenzenesulfonate is added at a metering rate of 8 kg/h. The time from 
the beginning of the reaction to pressure drop is 6 hours. 
The dispersion (solids content 46.9%) is worked up in a spray-drying 
installation. The inlet temperature of the dryer air is 160.degree. C., 
the outlet temperature is 60.degree. C. Otherwise, the working-up process 
takes place as described in DAS 2,146,146. A paste is prepared from 100 
parts by weight of the thus-obtained polyvinyl chloride powder and from 60 
parts by weight of di(2-ethylhexyl) phthalate (DOP), and the viscosity 
thereof is measured after a storage period of 2 and 24 hours at various 
shear rates in a rotation rheometer (instrument: Rheomat 30 by Contraves 
AG, Zuerich). The thickening factor TF is a measure for the shelf life of 
the paste. This factor is determined from the quotient of the viscosity 
value, taken after a storage period of 24 hours, divided by the viscosity 
value taken after 2 hours at a shear rate of D=1 s.sup.-1. Table 1 shows 
the paste viscosities at various shear rates, as well as the thickening 
factor TF. 
In order to test the blowing properties of the expanded polyvinyl chloride, 
a paste is prepared according to 10 the following formulation: 
______________________________________ 
100 parts polyvinyl chloride 
40 parts di(2-ethylhexyl) phthalate 
20 parts benzyl butyl phthalate 
3 parts azodicarbonamide 
1.5 parts Cd/Zn stabilizer 
______________________________________ 
The paste is de-aerated for one hour under vacuum. After a storage period 
of another 24 hours, the paste is knife-coated on a release paper with an 
application thickness of 1 mm and, with a residence time of 1.5 minutes, 
is gelled and expanded at 200.degree. C. in a gelling tunnel. 
The thus-obtained foam material is evaluated with respect to foam density 
and proportion by volume of closed and open cells. The latter is 
determined as follows: portions having a basal surface area of 100 
cm.sup.2 are punched out from the resultant, expanded specimens; these 
portions are introduced into a desiccator filled with water and evacuated 
so that the air is removed from the open cells. After aeration and removal 
of the specimen from the desiccator, the open cells have filled with 
water. By weighing the thus-absorbed quantity of water, the proportion by 
volume of the open cells can be calculated. The volume proportion of the 
plasticized polyvinyl chloride results from its density and the density of 
the foam. The percentage volume proportion of the closed cells then is 
obtained as the difference between 100% and the sum total of the volume 
proportion of open cells and plasticized polyvinyl chloride. The volume 
proportions of closed and open cells can be derived from Table 2. 
EXAMPLE 2 
A 6 m.sup.3 agitated autoclave is charged with 1,600 kg of demineralized 
water of a temperature of 60.degree. C. Under agitation, 22 kg of a 
mixture is added consisting of approximately equal parts of cetyl and of 
stearyl alcohol, 3 kg of sodium acetate, 9.25 kg of sodium di-2-ethylhexyl 
sulfosuccinate, as well as 1.5 kg of tert-butyl perbenzoate. After 
excluding atmospheric oxygen, 1,800 kg of vinyl chloride is added. This 
mixture is set at a temperature of 52.degree. C.; the agitator speed is 
set at 10 rpm. By the metered feeding of a 0.2% ascorbic acid solution, 
the reaction is started up. Further metered feeding is adjusted so that 
the polymerization temperature of 52.degree. C. is maintained with an 
almost fully exploited cooling capacity. Two hours after beginning of the 
reaction, metered feeding is started of 105 kg of a 10% aqueous solution 
of sodium di-2-ethylhexyl sulfosuccinate at a rate of 15 kg/h. The time 
from startup of reaction to pressure drop amounts to 8 hours. 
After the reaction is finished, the solids content of the dispersion is 
45.6%. The dispersion is worked up as described in Example 1. The paste 
viscosities of the powder, made into a paste with DOP in a ratio of 
100:60, and the thickening factor of the paste can be seen from Table 1. 
Expansion is effected as set forth in Example 1. The results can be 
derived from Table 2. 
EXAMPLE 3 
A 6 m.sup.3 agitated autoclave is charged with 1,600 kg of demineralized 
water of a temperature of 60.degree. C. Under agitation, the water is 
combined with 13.5 kg of lauric acid, 7.5 kg of sodium lauryl sulfate, 22 
kg of stearyl alcohol, as well as 1.2 kg of sodium hydroxide. After 
excluding atmospheric oxygen, 1,800 kg of vinyl chloride is added. The 
mixture is adjusted to a temperature of 52.degree. C., the agitator speed 
to 10 rpm. The reaction is started up with a 0.5% aqueous H.sub.2 O.sub.2 
solution and a 0.2% aqueous sodium formaldehyde sulfoxylate solution. 
One-half hour after beginning of the reaction, 80 kg of a 3% aqueous 
sodium hydroxide solution is added in metered quantities within 4 hours. 
The dispersion (solids content 47.1%) is worked up is in Example 1. The pH 
value of the aqueous product extract is adjusted to 5.5 with the aid of a 
6% oxalic acid solution dispensed in the spraying installation together 
with the product (mode of operation according to German Patent 2,531,780, 
Example 3). The paste viscosity, with DOP being incorporated into the 
paste with a ratio of 100:60, as well as the paste shelf life, can be seen 
from Table 1. 
Blowing is carried out as indicated in Example 1. The results are set forth 
in Table 2. 
EXAMPLE 4 
A 6 m.sup.3 agitated autoclave is charged with 1,600 kg of demineralized 
water of a temperature of 60.degree. C. Under agitation, 16.5 kg of sodium 
alkylbenzenesulfonate (mixtures of C.sub.10 -C.sub.13 
-alkylbenzenesulfonates), 22 kg of stearyl alcohol, as well as 3.7 kg of 
monosodium phosphate are added. After atmospheric oxygen has been 
excluded, 1,800 kg of vinyl chloride is added thereto. The mixture is set 
at 52.degree. C., the agitator speed at 10 rpm. The reaction is started up 
by the metered feeding of a 0.5% aqueous H.sub.2 O.sub.2 solution and a 
0.2% aqueous ascorbic acid solution. The further metering of the catalyst 
components is adjusted so that the polymerizing temperature of 52.degree. 
C. remains constant with almost full cooling capacity (jacket: 600,000 kJ 
per hour; reflux condenser: 120,000 kJ per hour). One hour after beginning 
of the reaction, 19.5 kg of a 20% aqueous solution of sodium 
alkylbenzenesulfonate is added in metered amounts at a rate of 8 kg/h. The 
time from beginning of the reaction to pressure drop is 6 hours. 
The dispersion (solids content 47.6%) is worked up in a spray-drying 
installation. The inlet temperature of the dryer air is 160.degree. C., 
the outlet temperature is 60.degree. C. Otherwise, working-up proceeds as 
described in DAS 2,146,146. A paste is prepared from 100 parts by weight 
of the resultant polyvinyl chloride powder and from 60 parts by weight of 
di(2-ethylhexyl) phthalate (DOP), and the viscosity of the paste is 
measured after 2 and 24 hours of storage at various shear rates in a 
rotation rheometer (instrument: Rheomat 30 of Contraves AG, Zuerich). The 
thickening factor TF is a measure for the shelf stability of the paste. 
This factor is determined from the quotient of the viscosity value, taken 
after a storage period of 24 hours, divided by the viscosity value taken 
after 2 hours, at a shear rate of D=1 s.sup.-1. Table 1 shows the paste 
viscosities at various shear rates as well as the thickening factor TF. 
In order to test the blowing properties of the expanded polyvinyl chloride, 
a paste is prepared according to the following formulation: 
______________________________________ 
100 parts polyvinyl chloride 
40 parts di(2-ethylhexyl) phthalate 
20 parts benzyl butyl phthalate 
3 parts azodicarbonamide 
1.5 parts Cd/Zn stabilizer 
______________________________________ 
The paste is de-aerated for one hour under vacuum. After a storage period 
of another 24 hours, the paste is knife-coated on a release paper with an 
application thickness of 1 mm and, with a residence time of 1.5 minutes, 
gelled and expanded at 200.degree. C. in a gelling tunnel. 
The foam density and the volume proportion of closed and open cells are 
determined in the resultant foam material. The volume proportion is 
determined as follows: Portions having a basal surface area of 100 
cm.sup.2 are punched out from the expanded specimens obtained above; these 
portions are transferred into a desiccator filled with water and evacuated 
so that the air is removed from the open cells. After aeration and 
withdrawal of the specimen from the desiccator, the open cells have filled 
with water. By weighing the thus-absorbed quantity of water, the volume 
proportion of open cells can be calculated. The volume proportion of 
plasticized polyvinyl chloride results from its density and the density of 
the foam. The percentage volume proportion of the closed cells then is 
obtained as the difference between 100% and the sum total of volume 
proportion of open cells and plasticized polyvinyl chloride. The volume 
proportions of closed and open cells can be derived from Table 2. 
EXAMPLE 5 
A 6 m.sup.3 agitated autoclave is charged with 1,600 kg of demineralized 
water having a temperature of 60.degree. C. The water is combined under 
agitation with 16.7 kg of myristic acid, 22 kg of stearyl alcohol, as well 
as 2.25 kg of sodium hydroxide. After exclusion of atmospheric oxygen, 
1,800 kg of vinyl chloride is added. The mixture is adjusted to a 
temperature of 52.degree. C., the agitator speed is set at 10 rpm. The 
reaction is started up with a 0.5% aqueous H.sub.2 O.sub.2 solution and a 
0.2% aqueous sodium formaldehyde sulfoxylate solution. One-half hour after 
beginning of the reaction, 71 kg of a 2% aqueous sodium hydroxide solution 
is added in metered amounts within 4 hours. 
The dispersion (solids content 47.1%) is worked up as described in Example 
4. The pH value of the aqueous product extract is set at 5.5 with the aid 
of a 6% oxalic acid solution concomitantly sprayed in the spraying 
installation (mode of operation in accordance with German Patent 
2,531,780, Example 3). Table 1 shows the paste viscosity, the paste 
containing DOP in a ratio of 100:60, as well as the paste shelf stability. 
Expansion is carried out as described in Example 4. The results are listed 
in Table 2. 
COMATIVE EXAMPLE A 
(German Application P 32 42 088.9 (U.S. Ser. No. 551,033)) 
A 2 m.sup.3 vessel is charged with 1,650 kg of demineralized water of a 
temperature of 60.degree. C. Under agitation, 18 kg of sodium 
alkylbenzenesulfonate (mixtures of C.sub.10 -C.sub.13 
-alkylbenzenesulfonates) and 22 kg of stearyl alcohol are added thereto. 
The mixture is passed through a single-stage piston pump homogenizer. The 
pressure in the homogenizing head is 180 bar; the recycle time (setting 
time) is 5 minutes. The homogenized mixture is conducted, under exclusion 
of atmospheric oxygen, to a 6 m.sup.3 agitated autoclave which can be 
cooled or heated by way of the jacket. (The autoclave is additionally 
equipped with a reflux condenser.) The mixture is combined with 1,800 kg 
of vinyl chloride and heated to 52.degree. C. The agitator speed is set at 
10 rpm. By the metered feeding of a 0.5% aqueous H.sub.2 O.sub.2 solution 
and a 0.2% aqueous ascorbic acid solution, the reaction is started up. The 
further feeding is set so that the polymerization temperature of 
52.degree. C. remains constant with an almost complete cooling capacity. 
The time to pressure drop is 5 hours. 
The dispersion (solids content 47.1%) is worked up as set forth in Example 
1. 
A paste is prepared from 100 parts by weight of the thus-obtained polyvinyl 
chloride powder and from 60 parts by weight of di(2-ethylhexyl) phthalate 
(DOP), and the viscosity of the paste is measured in a rotation rheometer 
at various shear rates after 2 and 24 hours of storage. The paste 
viscosities and the thickening factor can be derived from Table 1 Blowing 
is conducted as in Example 1. The results are shown in Table 2. 
COMATIVE EXAMPLE B 
The procedure of Comparative Example A is repeated, but using additionally 
1.5 kg of tert-butyl perbenzoate during preparation of the predispersion, 
and employing as the emulsifier 18 kg of sodium di-2-ethylhexyl 
sulfosuccinate. 
The polymerization reaction is started up by means of a 0.2% aqueous 
ascorbic acid solution and proceeds thus in a controlled fashion. 
After the reaction is finished, the solids content of the dispersion is 
46.5%. The dispersion is worked up as described in Example 1. The paste 
viscosities of the powder, made into a paste with DOP in a ratio of 
100:60, and the thickening factor of the paste can be derived from Table 
1. 
Blowing is performed as in Example 1. The results are found in Table 2. 
COMATIVE EXAMPLE C 
The procedure of Comparative Example B is followed, but using as the 
emulsifier a mixture of 15 kg of sodium laurate and 7.5 kg of sodium 
lauryl sulfate. Furthermore, 0.9 kg of sodium hydroxide is added to the 
water. The reaction is started and controlled with a 0.5% aqueous H.sub.2 
O.sub.2 solution and a 0.2% aqueous sodium formaldehyde sulfoxylate 
solution. 
The dispersion is worked up as described in Example 3 (solids content 
46.3%). The paste viscosities of the powder, made into a paste with DOP in 
a ratio of 100:60, as well as the paste storage stability can be seen from 
Table 1. 
Blowing is performed as in Example 1. The results are compiled in Table 2. 
COMATIVE EXAMPLE D 
(German Application P 32 10 891.5 (U.S. Ser. No. 478,766)) 
A 50 liter vessel is charged with 17 kg of water at 60.degree. C. Under 
agitation, the water is combined with 4.3 kg of a 21% aqueous sodium 
alkylbenzenesulfonate solution (mixture of C.sub.10 -C.sub.13 
-alkylbenzenesulfonates) and 1.3 kg of an aqueous sodium salt solution of 
the sulfosuccinic acid diethylhexyl ester (70% by weight), as well as 1.8 
kg of a mixture of about equal parts of cetyl alcohol and of stearyl 
alcohol. 
Under exclusion of atmospheric oxygen, an agitated autoclave having a 
capacity of 500 1, equipped with heating and cooling units, is charged 
with 120 l of demineralized water, 0.2 l of the previously prepared 
emulsifier solution, 260 g of monosodium phosphate. The mixture is heated 
to 52.degree. C. To this mixture is added 45 kg of vinyl chloride. By 
metered feeding of a 0.5% aqueous H.sub.2 O.sub.2 solution and a 0.2% 
aqueous ascorbic acid solution in respectively equal parts, the reaction 
is started up. 
The feeding of activator is adjusted so that the polymerization temperature 
of 52.degree. C. remains constant with an almost full cooling capacity. 
During the further course of polymerizing, another 135 kg of vinyl 
chloride is fed in metered amounts within 3 hours. The remainder of the 
emulsifier solution is distributed as follows during the reaction period: 
______________________________________ 
Time (h) 1 2 3 4 
______________________________________ 
Emulsifier (1) 
0.5 5.8 10.3 10.7 
______________________________________ 
The dispersion (solids content 48.5%) is worked up as indicated in Example 
3. The paste viscosities of the powder, made into a paste with DOP in a 
ratio of 100:60, as well as the paste shelf stability can be seen from 
Table 1. 
Blowing is executed as in Example 1. The results are set forth in Table 2. 
TABLE 1 
__________________________________________________________________________ 
Paste Viscosity (d Pas) 
Conc. of Emulsi- 
fier System 
D = D = D = D = Based on 
0.3 s.sup.-1 
1 s.sup.-1 
10 s.sup.-1 
100 s.sup.-1 Vinyl Chloride 
2 h 
24 h 
2 h 
24 h 
2 h 
24 h 
2 h 
24 h 
TF (%) 
__________________________________________________________________________ 
Example 1 
43 54 31 38 25 30 29 33 1.2 2.4 
Example 2 
56 72 38 42 33 34 38 41 1.1 2.3 
Example 3 
72 110 
51 66 52 60 75 80 1.3 2.4 
Example 4 
45 57 32 41 26 34 31 36 1.28 
Example 5 
75 118 
46 58 33 45 36 48 1.26 
Comp. Ex. A 
62 79 36 45 24 30 24 31 1.3 2.2 
Comp. Ex. B 
53 66 39 45 35 36 40 42 1.2 2.2 
Comp. Ex. C 
240 
-- 180 
-- 130 
-- 120 
-- -- No longer 
2.4 
measurable 
after 24 h 
Comp. Ex. D 
72 130 
55 100 
44 80 41 77 1.8 2.0 
__________________________________________________________________________ 
Interpretation of Table 1 
As can be seen from the measured viscosities, the process of this invention 
also shows very low paste viscosities as the result. As demonstrated by 
Comparative Example C, only this makes it possible to produce pastes that 
can be processed. Besides, the storage stability of the pastes is better 
than in the comparative examples. 
TABLE 2 
______________________________________ 
Foam Properties 
Volume Volume 
Proportion 
Proportion 
Open Cells 
Closed Cells 
(%) (%) 
______________________________________ 
Example 1 64.0 15.1 
Example 2 48.1 20.2 
Example 3 60.9 14.9 
Example 4 61.2 17.4 
Example 5 58.5 18.2 
Comp. Ex. A 2.0 75.6 
Comp. Ex. B 15.6 54.1 
Comp. Ex. C 2.7 75.1 
Comp. Ex. D 5.1 70.4 
______________________________________ 
As apparent from the above, the polymers produced according to this 
invention make it possible to obtain foam materials having a predominantly 
open-cell structure which, as is known, show a good elastic memory 
capacity. 
The preceding examples can be repeated with similar success by substituting 
the generically or specifically described reactants and/or operating 
conditions of this invention for those used in the preceding examples. 
From the foregoing description, one skilled in the art can easily ascertain 
the essential characteristics of this invention, and without departing 
from the spirit and scope thereof, can make various changes and 
modifications of the invention to adapt it to various usages and 
conditions.