Water-soluble polymers and use as building material auxiliaries

The present invention relates to new water-soluble copolymers based on acrylic acid derivatives and their use as building material auxiliaries.

The present invention relates to new water-soluble copolymers based on 
acrylic acid derivatives and their use as building material auxiliaries. 
Wearing floors, for example wooden parquet, tiles or floor coverings made 
of plastic, can be laid only on horizontal and absolutely level floor 
surfaces. When buildings are erected, however, only uneven concrete 
surfaces are obtained in the carcass, so that for this reason a screed 
usually first has to be applied to these uneven concrete floors. 
Whilst screeds of bituminous mastic concrete, cement or magnesite were 
previously used to produce the horizontal and level surfaces required and 
involved a considerable expenditure of labour for their application, 
levelling and smoothing, mortar mixtures which, after addition of water, 
have a flowable and pumpable consistency and can be levelled and smoothed 
onto the uneven floor itself under the influence of gravity, like a 
liquid, have also been known for some time. 
Thus, a mortar composition which consists of anhydride, if appropriate 
sand, an activator, a resin which is modified with sulphide or sulphonic 
acid and is based on an amino-s-triazine with at least 2 NH.sub.2 groups, 
as an additive which increases strength, a wetting agent and, if 
appropriate, an antifoaming agent, is known from DE-OS (German Published 
Specification) No. 1,943,634. Melamine/formaldehyde condensation products, 
which are added as a concrete plasticizer, are used here. A concrete 
mixture which can be pumped as easily as possible, has extremely good flow 
properties and hardens as rapidly as possible is to be obtained by 
plasticizing the concrete. 
The disadvantage of these products based on melamine/formaldehyde is that 
their plasticizing properties persist only for approximately 15 minutes. 
Furthermore, the requirements of a flow control agent in a self-levelling 
flow screed are in principle different from those of a concrete 
plasticizer. Thus, completely homogeneous flow of the screed composition 
is required with a flow control agent for a self-levelling flow screed. In 
particular, no sedimentation of the heavier constituents should occur 
during flow. The flow control auxiliary for concrete screed must thus have 
a certain carrying capacity for the building material mixture. Since it is 
entirely possible for delays to occur on the building site during 
application of the flow screed, it is necessary for the flow screed 
auxiliary also still to retain its full effectiveness 1 hour after 
addition to the building material mixture. 
However, sedimentation of the heavier constituents during flow occurs with 
auxiliaries based on melamine/formaldehyde condensation products. 
Furthermore, after 1 hour, it is not possible for the flow screed mixture 
to be brought back, by stirring, into a satisfactorily flowable state, so 
that homogeneous flow is achieved. Attempts have also been made to improve 
the carrying capacity by additives. However, this has not been completely 
satisfactory. 
Surprisingly, it is now possible, with the polymers according to the 
invention, to provide flow control auxiliaries for building material 
mixtures which are added in only small amounts and effect the desired 
homogeneous flow of building material mixtures to give screeds with an 
absolutely level surface. It is not necessary here to add any auxiliaries 
and additives to achieve homogeneous flow. A particular advantage of these 
polymers according to the invention is that their full effectiveness is 
also still retained 1 hour after addition to the building material 
mixture. 
The invention thus relates to water-soluble copolymers which consist to the 
extent of 
(1) 5 to 50 mol %, preferably 10 to 40 mol %, of radicals of the formula I 
##STR1## 
(2) 0 to 20 mol %, preferably 0 to 15 mol %, of radicals of the formula II 
##STR2## 
(3) 5 to 50 mol %, preferably 20 to 50 mol %, of radicals of the formula 
III 
##STR3## 
(4) 5 to 50 mol %, preferably 10 to 40 mol %, of radicals of the formula 
IVa or IVb 
##STR4## 
(5) 2 to 50 mol %, preferably 5 to 30 mol %, of radicals of the formula V 
##STR5## 
and (6) 5 to 50 mol %, preferably 5 to 30 mol %, of radicals of the 
formula VI 
##STR6## 
and in which the sum of (1) to (6) must always give 100 mol %, and to 
their use as building material auxiliaries, in particular as flow control 
auxiliaries, in self-levelling screed mixtures and floor-levelling 
compositions. 
In the radicals I to VI of the randomly built up polymers: 
R.sub.1 denotes hydrogen or a methyl group, 
R.sub.2 denotes an alkoxycarbonyl group with 1 to 4 C atoms in the alkoxy 
group, preferably an ethyloxy-, isobutyloxy- or tert.-butyloxycarbonyl 
group, an alkanoyloxy group with 1 to 4 C atoms or a 
.beta.-hydroxyalkoxycarbonyl group with 2 or 3 C atoms, 
R.sub.3 denotes a methyl or an ethyl group, 
R.sub.4 denotes hydrogen or a methyl group, 
R.sub.5 and R.sub.6 are identical or different and denote hydrogen or a 
methyl or ethyl group, or together form a trimethylene or pentamethylene 
ring, 
R.sub.7 denotes hydrogen or a methyl group, and 
Y denotes a covalent bond or a group of the formula 
##STR7## 
and X denotes an imidazole or carbazole radical. 
The polymers according to the invention can also preferably be reacted with 
lower aliphatic aldehydes, preferably formaldehyde, and sodium bisulphite, 
0.1 to 1 mol, preferably 0.4 to 0.8 mol/per mol of the radicals of the 
formula III of aldehyde being added. The sodium bisulphite is preferably 
employed in an equimolar proportion relative to the aldehyde. 
Copolymers which are derived from ethyl acrylate, vinyl acetate, 
acrylamide, 1-vinyl-2-pyrrolidone, acrylic acid and 
2-acrylamido-2-methylpropanesulphonic acid, and reaction products of these 
copolymers with formaldehyde and sodium bisulphite, are particularly 
preferred. 
The excellent activity of the copolymers according to the invention as flow 
control auxiliaries in building material mixtures was completely 
surprising, since copolymers built up similarly from, for example, 
acrylamide, AMPS and vinylpyrrolidone are completely unsuitable. 
The polymers according to the invention can be prepared in a manner which 
is known per se, for example by free radical polymerization in aqueous 
solution. 
The polymerization is thereby carried out in the customary manner under an 
inert gas atmosphere, preferably under nitrogen. The polymerization 
temperature should be between 20.degree. and 100.degree. C., preferably 
between 30.degree. and 60.degree. C. 
The polymerization can be started by the customary polymerization 
initiators, for example K.sub.2 S.sub.2 O.sub.8, H.sub.2 O.sub.2, 
(NH.sub.4).sub.2 S.sub.2 O.sub.8 or an H.sub.2 O.sub.2 /isoascorbic acid 
mixture. As a rule 1 to 10 g of polymerization initiator are employed per 
100 g of monomers. 
For carrying out the polymerization, the monomers are preferably dissolved 
in water in a concentration in the range from 20 to 40% by weight of the 
total monomers. A surfactant can be added for better distribution of the 
water-insoluble monomers. Since the aim is to obtain polymers with chains 
which are as short as possible, relatively large amounts of a chain length 
regulator are employed. Hydroquinone, isopropanol or other suitable chain 
length regulators can be used for this purpose. After rinsing with 
nitrogen, the reaction is started. The copolymers can also advantageously 
be reacted with formaldehyde and sodium bisulphite, in order to increase 
the content of sulphonic acid groups in the finished product. 
The copolymer according to the invention can be isolated from the aqueous 
solution by distilling off the water or by precipitation by mixing the 
solution with a water-miscible organic solvent, such as methanol, ethanol, 
acetone or the like. Preferably, however, the aqueous solution of the 
reaction product is used directly, if appropriate after adjustment of a 
desired concentration, as a flow control auxiliary for screed mixtures. 
The copolymers according to the invention are outstandingly suitable as 
auxiliaries for building material mixtures. They effect homogeneous, 
uniform flow of screed mixtures to give a completely level, smooth 
surface. It is particularly advantageous that these copolymers according 
to the invention also still fully retain their effectiveness after 1 hour 
after addition of the polymer to the building material mixture. An 
outstanding flow control agent for use in screed mixtures and floor 
levelling compositions is thus available. 
The invention therefore also relates to building material mixtures, in 
particular screed mixtures, based on cement, sand and fly ash, which are 
characterized in that they contain the copolymers according to the 
invention as flow control agents. 
For formulation of flow screed mixtures of the flow control auxiliary, such 
as, for example, the known auxiliary based on melamine/formaldehyde 
condensation products, are usually employed in amounts of 0.4 to 0.8% by 
weight, based on the solid employed. With the copolymers according to the 
invention, however, it is possible for outstanding flow of screed mixtures 
already to be achieved when only 50% of the hitherto customary amounts are 
employed. The flow control auxiliary according to the invention thus 
already displays its full effectiveness in amounts of 0.05 to 1% by 
weight, preferably 0.15 to 0.4% by weight, based on the solids. The screed 
mixtures are preferably based on cement, sand and fly ash.

EXAMPLE 1 
329 g of deionized water are taken in a 1 l polymerization flask with a 
stirrer, reflux condenser and gas inlet tube for an inert gas. 22.58 g of 
ethyl acrylate are then added. This amount corresponds to 0.2256 mol of 
ethyl acrylate. 
9.06 g of vinylacetate=0.1053 mol, 128.3 g of 30% strength aqueous 
acrylamide solution=0.5414 mol, 40.07 g of 1-vinyl-2-pyrrolidone=0.3610 
mol, 8.67 g of acrylic acid=0.1203 mol and 62.26 g of a 50% strength 
solution of sodium 2-acrylamido-2-methylpropanesulphonate (AMPS) are then 
added. 
These amounts of monomers used correspond to a composition of 15 mol % of 
ethyl acrylate, 7 mol % of vinyl acetate, 36 mol % of arylamide, 24 mol % 
of 1-vinyl-2-pyrrolidone, 8 mol % of acrylic acid and 10 mol % of AMPS. 
Hyddroquinone in an amount of 6 g of a 1% strength solution=0.04%, based on 
the total amount of monomers weighed out, is employed as a chain length 
regulator. In order to achieve better distribution of the water-insoluble 
monomers, a solution of the anionic surfactant sodium alkyl-diglycol 
ether-sulphate, based on naturally occurring fatty alcohols 
R--O--(CH.sub.2 --CH.sub.2 --O).sub.2 --SO.sub.2 Na alkyl=75-70% C.sub.12, 
25-30% C.sub.14 (Genopol LRO.RTM., liquid) is added in an amount of 3.16 g 
of a 1% strength solution=0.1%, on the sum of vinyl acetate and the amount 
of ethyl acrylate weighed out. 
After the end of the addition, the mixture is stirred at a speed of 350 to 
400 rpm and is flushed with about 10 l/hour of nitrogen, in order to 
displace the oxygen from the solution. This flushing with nitrogen is 
maintained throughout the entire reaction time. The residual oxygen 
content at the start of the polymerization is advantageously between 1.2 
and 1.8 ppm. The pH value of the reaction mixture is about 2.1. The 
reaction mixture is warmed to 35.degree. C. 
After flushing with about 10 l/hour of nitrogen for about 20 minutes, the 
polymerization reaction is started by addition of 0.75 g of K.sub.2 
S.sub.2 O.sub.8 =0.5% (all the amounts of initiator are based on the 
amount of monomer weighed out). After 1 hour, a further 0.75 g of K.sub.2 
S.sub.2 O.sub.8 =0.5%, based on the amount of monomer weighed out, is 
added. After 2 hours, 1.5 g of K.sub.2 S.sub.2 O.sub.8 =1% are added. 4 
hours after the start of the reaction, the reaction mixture becomes 
slightly viscous and a further 1.5 g of K.sub.2 S.sub.2 O.sub.8 =1% are 
added. After 6 hours, the reaction has ended and 11.19 g of 50% strength 
sodium hydroxide solution are added in order to raise the pH value from 
1.9 to 6.2. 
The end product obtained is characterized by the following data: 
______________________________________ 
pH value: 6.4 
Concentration: 24% by weight 
Viscosity (VT.sub.24 Haake): 
100 mPa.s at 25.degree. C. 
Limiting viscosity (.eta.): 
0,32 g .multidot. dl.sup.-1 
______________________________________ 
(measured on a 1% strength NaCl solution at 25.degree. C.) 
Polymers 2 to 33, the composition of which can be seen from Table 1, can be 
prepared analogously to Example 1. 
EXAMPLE 34 
324.3 g of deionized water are taken in a 1 l polymerization flask with a 
stirrer, reflux condenser and gas inlet tube for an inert gas. 34.9 g of 
ethyl acrylate are then added. This amount corresponds to 0.3405 mol of 
ethyl acrylate. 
142.15 g of a 30% strength aqueous acrylamide solution=0,600 mol, 37.8 g of 
1-vinyl-2-pyrrolidone=0,3405 mol, 18.69 g of acrylic acid=0,2594 mol and 
33.57 g of a 50% strength solution of sodium 
2-acrylamido-2-methylpropanesulphonate (AMPS)=0,0811 mol are then added. 
These amounts of monomers employed correspond to a composition of 21 mol % 
of ethyl acrylate, 37 mol % of acrylamide, 21 mol % of 
1-vinyl-2-pyrrolidone, 16 mol % of acrylic acid and 5 mol % of AMPS. 
Hydroquinone in an amount of 6 g of a 1strength solution=0.04%, based on 
the total amount of monomer weighed, is added as the chain length 
regulator. In order to achieve a better distribution of the 
water-insoluble monomers, a solution of the surfactant Genapol is added in 
an amount of 3.41 g of a 1% strength solution=0.1%, on the amount of ethyl 
acrylate weighed out. 
After the end of the additions, the mixture is stirred at a speed of 350 to 
400 rpm and is flushed with about 10 l/hour of nitrogen in order to 
displace the oxygen from the solution. This flushing with nitrogen is 
maintained throughout the entire reaction time. The residual oxygen 
content at the start of the polymerization is advantageously between 1.2 
and 1.8 ppm. The pH value of the reaction mixture is about 2.8. The 
reaction mixture is warmed to 35.degree. C. 
After flushing with about 10 l/hour of nitrogen for 20 minutes, the 
polymerization reaction is started by addition of 0.75 g of K.sub.2 
S.sub.2 O.sub.8 =0.5% (all the amounts of initiator are based on the 
amount of monomer weighed out). After 1 hour, a further 0.75 g of K.sub.2 
S.sub.2 O.sub.8 =0.5%, based on the amount of monomer weighed out, is 
added. 4 hours after the start of the reaction, the reaction mixture 
becomes slightly viscous and a further 1.5 g of K.sub.2 S.sub.2 O.sub.8 
=1% are added. The reaction has ended after 6 hours. 
The intermediate product obtained is characterized by the following data: 
______________________________________ 
pH value: 2.6 
Concentration: 24% by weight 
Viscosity (VT.sub.24 Haake): 
200 mPa.s at 25.degree. C. 
______________________________________ 
After the polymerization, the reaction of the polymer with formaldehyde and 
sodium bisulphite is carried out. 
For this, the polymer solution is brought to a pH value of 8.9 at 
20.degree. C. with 15.31 g of 50% strength sodium hydroxide solution and 
12.17 g of 25% strength sodium hydroxide solution. 
Thereafter, 20.66 ml of 40% strength formaldehyde solution are added and 
the mixture is heated up to 50.degree. C., with continuous stirring. The 
temperature of 50.degree. C. is maintained for 2 hours. 
31.22 g of NaHSO.sub.3 are now added, and the mixture is heated up to a 
temperature of 60.degree. C. 
The reaction has ended after 1 hour at 60.degree. C. 
The solution obtained can be used directly. Polymers 35 to 40 the 
composition of which can be seen from Table 1, can be prepared analogously 
to Example 34. 
The following abbreviations are used in Table 1: 
AMPS: sodium 2-acrylamido-2-methylpropanesulphonate 
NVPY: 1-vinyl-2-pyrrolidone 
AAM: acrylamide 
EA: ethyl acrylate 
IBA: isobutyl acrylate 
TBA: tert.-butyl acrylate 
HEA: hydroxyethyl acrylate 
HPA: hydroxypropyl acrylate 
VAC: vinyl acetate 
VMACAM: N-vinyl-N-methylacetamide 
NVSA: sodium vinylsulphonate 
NASS: sodium styrenesulphonate 
AA: acrylic acid 
MAA: methacrylic acid 
MA: methacrylate 
HPMA: hydroxypropyl methacrylate 
HEMA: hydroxyethyl methacrylate 
VCLT: vinylcaprolactam 
TABLE 1 
__________________________________________________________________________ 
Example 
No. mol % 
Mon. 1 
mol % 
Mon. 2 
mol % 
Mon. 3 
mol % 
Mon. 4 
mol % 
Mon. 5 
mol % 
Mon. 
Viscosity 
__________________________________________________________________________ 
1 15 EA 7 VAC 36 AAM 24 NVPY 8 AA 10 AMPS 
100 
2 40 EA 32 AAM 10 NVPY 8 AA 10 AMPS 
300 
3 15 EA 7 VAC 30 AAM 30 NVPY 8 AA 10 AMPS 
100 
4 15 EA 7 VAC 30 AAM 20 NVPY 8 AA 20 AMPS 
200 
5 15 EA 7 VAC 28 AAM 20 NVPY 20 AA 10 AMPS 
300 
6 15 EA 7 VAC 24 AAM 16 NVPY 8 AA 30 AMPS 
200 
7 15 EA 7 VAC 16 AAM 24 NVPY 8 AA 30 AMPS 
100 
8 40 EA 20 AAM 10 NVPY 8 AA 22 AMPS 
300 
9 15 EA 7 VAC 43 AAM 10 VMACAM 
8 AA 17 AMPS 
1,400 
10 15 EA 7 VAC 36 AAM 24 VMACAM 
8 AA 10 AMPS 
300 
11 15 HPA 7 VAC 36 AAM 24 NVPY 8 AA 10 AMPS 
200 
12 15 EA 7 VAC 36 AAM 24 NVPY 8 MAA 10 AMPS 
200 
13 30 EA 32 AAM 20 NVPY 8 AA 10 AMPS 
300 
14 10 EA 5 VAC 47 AAM 20 NVPY 8 AA 10 AMPS 
200 
15 15 EA 7 VAC 50 AAM 10 NVPY 8 AA 10 AMPS 
400 
16 15 EA 7 VAC 18 AAM 12 NVPY 8 AA 40 AMPS 
200 
17 15 EA 7 VAC 50 AAM 10 NVPY 8 AA 10 AMPS 
400 
18 22 EA 36 AAM 21 NVPY 4 AA 17 AMPS 
200 
20 15 MA 7 VAC 36 AAM 24 NVPY 8 AA 10 AMPS 
100 
21 15 HEMA 7 VAC 36 AAM 24 NVPY 8 AA 10 AMPS 
300 
22 15 HPMA 7 VAC 36 AAM 24 NVPY 8 AA 10 AMPS 
200 
23 15 HEA 7 VAC 36 AAM 24 NVPY 8 AA 10 AMPS 
200 
24 15 EA 7 VAC 36 AAM 24 NVPY 8 AA 10 AMPS 
900 
25 11 EA 11 VPP 36 AAM 24 NVPY 8 AA 10 AMPS 
200 
26 15 EA 7 VPP 36 AAM 24 NVPY 8 AA 10 AMPS 
200 
27 7 HEA 44 AAM 17 NVPY 11 AA 17 AMPS 
500 
28 20 VPP 7 VAC 27 AAM 17 NVPY 19 AA 10 AMPS 
200 
29 8 HEA 23 TBA 26 AAM 15 NVPY 19 AA 9 AMPS 
400 
30 10 TBA 36 AAM 21 NVPY 23 AA 10 NAVS 
200 
31 17 EA 36 AAM 21 NVPY 21 AA 5 AMPS 
700 
32 11 EA 11 VAC 36 AAM 21 NVPY 11 AA 10 AMPS 
200 
33 15 IBA 36 AAM 21 NVPY 18 AA 10 NAVS 
4,000 
34 21 EA VAC 37 AAM 21 NVPY 16 AS 5 AMPS 
200 
35 21 EA 27 AAM 21 NVPY 11 AA 20 AMPS 
100 
36 15 EA 7 VAC 24 AAM 16 NVPY 8 AA 30 AMPS 
200 
37 15 EA 7 VAC 28 AAM 20 NVPY 20 AA 10 AMPS 
300 
38 40 EA 32 AAM 10 NVPY 8 AA 10 AMPS 
300 
39 15 EA 7 VAC 30 AAM 300 NVPY 8 AA 10 AMPS 
100 
40 30 EA 32 AAM 20 NVPY 8 AA 10 AMPS 
300 
__________________________________________________________________________ 
In the following use examples, the polymers according to the invention are 
compared with known flow control agents for building material mixtures. 
For this use, it is particularly important that the flow control agent 
leads to the flow screed composition being spread as widely as possible in 
the space in question. 
The so-called degree of spreading under standardized conditions is used in 
technological tests to measure this flow control effect. It is also 
particularly important that the flow screed mixture also still retains its 
full effectiveness after 1 hour. For this reason, the degree of spreading 
is determined again after 1 hours. The degree of spreading after 1 hour 
should, in the ideal case, be exactly the same as the degree of spreading 
immediately after preparation of the flow screed mixture. In order to 
guarantee steady building progress, it must be possible to walk on the 
flow screed after 16 hours (that is to say on the morning of the following 
working day). For this reason, the hardening after 16 hours is checked in 
the laboratory test for use of the flow screed. 
The flow screed test is carried out as follows: 
The following recipe is used: 
______________________________________ 
175 g of cement PZ 35 
175 g of fly ash 
725 g of sand with a particle size of 0 to 
2 mm 
total 1,075 g of solid 
______________________________________ 
The amounts of flow control agents (polymers) and antifoaming agents added 
are based on this amount of solids of 1,075 g. 
The following additives are used in all the use examples: 
0.2% of flow control agent (100% pure), based on the basic recipe amount, 
and 
0.1% of antifoaming agent SB 2030 S, based on the basic recipe amount 
The amount of water depends on the flow properties of the screed. An 
initial total water amount of 105 ml is taken as a basis, and water is 
metered in as required. This initial total water amount contains the water 
introduced by the polymer with its solution. 
Test procedure 
The sand, the cement and the fly ash are mixed in the dry state in a 
laboratory mixer for 2 minutes. The polymer solution, the antifoaming 
agent and the water are weighed out into a glass beaker and stirred and 
the mixture is then poured into the homogeneous dry mixture of sand, 
cement and fly ash, the dry mixture being stirred. 
After 2 minutes, the mixing process is interrupted and the sample is 
evaluated according to whether the surface flows completely smoothly 
within 15 to 30 seconds. If this property is not yet achieved, water is 
added in steps of 5 ml and this amount of water is then stirred in for 1 
minute. The stirring operation is then interrupted again and the sample is 
again evaluated as to whether the surface flows completely smoothly within 
15 to 30 seconds. Shortly before this completely smooth flow is achieved, 
the water is added in steps of only 1 ml. 
The amount of water required to achieve a completely smooth flow should be 
as low as possible, in order to avoid cracking in the screed. 
After completely smooth flow has been achieved, the degree of spreading is 
determined. Up to this point in time, the screed must have been stirred 
for a total of 10 minutes. The degree of spreading is then determined. 
Determination of the degree of spreading 
A cylinder made of plastic and with a diameter of 7 cm and a height of 8.5 
cm standing in the middle of a dish of plastic with a diameter of 32 cm, 
is filled to the brim with the flow screed. Thereafter, the cylinder made 
of plastic is raised so that the flow screed can flow apart. After 3 
minutes, the average diameter of the pancake of flow screed which has 
spread out is determined by several measurements. This measurement 
indicates the degree of spreading. During flow of the screed, its surface 
is also simultaneously evaluated, and should be as smooth as possible. The 
flow of the screed should also as far as possible lead to a circular 
shape. 
After the degree of spreading has been determined, a polystyrene beaker is 
filled with the entire screed composition and the composition is left to 
stand for 1 hour. After this time, calculated from the addition of the 
polymer solution to the dry mixture, the surface of the screed is tested 
for any formation of a skin. The screed is then stirred thoroughly, and is 
evaluated as to whether the screed has already set to a substantial 
degree. It should be possible to render the screed readily flowable again 
by stirring. 
The degree of spreading is then determined again, as described above, and 
the surface is evaluated. 
Finally, a polystyrene beaker is filled with a sample of 100 g of screed 
and this sample is left to harden for 16 hours. 
Testing of the hardening 
Hardening of the sample is tested by pressing firmly on the surface with a 
finger. If the surface of the screed gives, it cannot be walked on. This 
is a coarse preliminary test. 
The hardening is additionally investigated with a needle apparatus 
according to Vickert. In this, it is investigated whether a metal needle 
with a diameter of about 1 mm and loaded with a weight of 300 g penetrates 
into the sample. 10 measurements are carried out and the mean value of the 
penetration depth is determined from these measurements. The screed is 
regarded as hardened if the needle could not penetrate the screed on any 
of the 10 measurements. 
The following samples were used for the investigations: 
A. Copolymer (according to the invention), consisting of 15 mol % of ethyl 
acrylate, 7 mol % of vinyl acetate, 36 mol % of acrylamide, 24 mol % of 
1-vinyl-2-pyrrolidone, 8 mol % of acrylic acid and 10 mol % of AMPS 
(Example 1, Table 1). 
B. Modified copolymer (according to the invention), prepared with a 
composition of 21 mol % of ethyl acrylate, 37 mol % of acrylamide, 21 mol 
% of 1-vinyl-2-pyrrolidone, 16 mol % of acrylic acid and 5 mol % of AMPS. 
This polymer was also reacted with formaldehyde and sodium bisulphite 
after the polymerization (Example 34, Table 1). 
C. Commercially available melamine/formaldehyde condensation product 
intended for use as a concrete plasticizer (comparison product). 
The results of the investigations with these products and with the flow 
control agents according to Example No. 2, 3, 5, 9, 11, 15, 16 and 22 are 
summarized in Table 2: 
TABLE 2 
__________________________________________________________________________ 
Degree of spreading 
Water immediately after 
Degree of spreading 
Flow control 
consumption 
preparation of the 
1 hour after addition of the 
Remarks on flow 
Hardening determined 
agent in ml screed in ml 
flow control agent in ml 
after 1 hour according to 
__________________________________________________________________________ 
Vickert 
A 129 250 265 easy to liquefy by 
hardened 
ring; flows smoothly with- 
out sedimentation 
B 123 245 230 easy to liquefy by 
hardened; 
flows smoothly without 
sedimentation 
C 140 165 165 does not flow, uneven 
hardened 
face, marked curvature of 
the screed pancake 
Example 2 
128 250 230 easy to liquefy by 
hardened; 
flows smoothly without 
sedimentation 
Example 3 
128 240 225 easy to liquefy by 
hardened; 
flows smoothly without 
sedimentation 
Example 5 
125 265 225 easy to liquefy by 
hardened; 
flows smoothly without 
sedimentation 
Example 9 
131 245 210 easy to liquefy by 
hardened; 
flows smoothly without 
sedimentation 
Example 11 
126 250 240 easy to liquefy by 
hardened; 
flows smoothly without 
sedimentation 
Example 15 
124 260 255 easy to liquefy by 
hardened; 
flows smoothly without 
sedimentation 
Example 16 
112 255 230 easy to liquefy by 
hardened; 
flows smoothly without 
sedimentation 
Example 22 
129 190 210 easy to liquefy by 
hardened; 
flows smoothly without 
sedimentation 
__________________________________________________________________________ 
The results of the technological investigations clearly show the superior 
effectiveness of the flow control agents according to the invention 
compared with comparison product C. 
Very much higher degrees of spreading immediately after preparation of the 
screed are achieved with the products according to the invention than with 
comparison product C. The products according to the invention 
advantageously flow completely smoothly, without sedimentation, whilst 
comparison product C leads only to an uneven flow of the screed pancake, 
even with the higher amount of water, and the pancake also still has a 
curvature. 
The superiority of the products according to the invention becomes 
particularly clear in the determination of the degree of spreading 1 hour 
after addition of the flow control agent. 
Here, both products according to the invention still have the 
insignificantly changed high initial degree of spreading and effect a 
completely smooth flow of the screed, without sedimentation. 
Comparison product C, in contrast, is not flowable and leads to a screed 
pancake with an uneven surface and marked curvature. 
The products according to the invention thus achieve a far higher 
effectiveness than the products known hitherto and thus represent a 
substantial improvement of the prior art.