Process for the production of water-soluble auxiliaries for the papermaking industry by reacting PA0 (a) 1 part by weight of a polyamidoamine obtained by condensing 1 mole of a dicarboxylic acid having from 4 to 10 carbon atoms with from 0.8 to 1.4 moles of a polyalkylene polyamine having from 3 to 10 alkyleneamine units and containing up to 8 ethyleneimine units per basic nitrogen atom with (b) 0.1 to 4 parts by weight of an .alpha.,.omega.-dichloro polyalkylene oxide obtained by reacting a polyalkylene oxide having from 8 to 100 alkylene oxide units with a compound selected from the group consisting of a thionyl chloride and phosgene and then cleaving the reaction products by heating them to a temperature of from 70.degree. to 150.degree. C. in the presence of a tertiary amine as catalyst, as crosslinking agent, at a temperature above 20.degree. C. in aqueous solution or in a water-soluble organic solvent, the reaction being carried out to a point at which the viscosity of an aqueous solution containing 20% by weight of auxiliary is from 300 to 2,500 mPas.

The present invention relates to a process for the preparation of 
nitrogen-containing condensates by reacting polyamidoamines, which have 
been prepared from 1 mole of a dicarboxylic acid of 4 to 10 carbon atoms 
and 0.8-1.4 moles of a polyalkylenepolyamine which has 3-10 basic nitrogen 
atoms in the molecule and may contain up to 10% by weight of a diamine, 
and onto which up to 8 ethyleneimine units per basic nitrogen may or may 
not have been grafted, with difunctional crosslinking agents at above 
20.degree. C., until a high molecular weight resin is formed which is only 
just water-soluble and which has a viscosity, measured in 20% strength 
aqueous solution at 20.degree. C., of more than 300 mPas. 
A process of this type, wherein polyalkylene oxides which contain from 8 to 
100 alkylene oxide units and which have been reacted, at the terminal OH 
groups, with at least an equivalent amount of epichlorohydrin, are used as 
crosslinking agents is disclosed in German Laid-Open Application DOS No. 
2,434,816. However, it has been found a disadvantage that the conventional 
crosslinking agent is very difficult to obtain in a pure form and always 
contains by-products which result from the etherification reaction of the 
terminal hydroxyl groups of the polyether-diol with epichlorohydrin. 
It is an object of the present invention to provide a difunctional 
crosslinking agent, for the process referred to at the outset, which is 
cheaply obtainable in a pure form and which gives products which are even 
more effective when used as retention agents, flocculating agents and 
drainage accelerators in the manufacture of paper. 
We have found that this object is achieved, according to the invention, if, 
in the process described at the outset, 1 part by weight of one of the 
stated polyamidoamines is reacted with from 0.1 to 4 parts by weight of a 
polyalkylene oxide, which contains from 8 to 100 alkylene oxide units and 
in which the terminal OH groups have been replaced by chlorine, as the 
difunctional crosslinking agent. 
The nitrogen-containing condensation products thus obtained do not contain 
any impurities which interfere with their use and are more active than the 
crosslinking agents disclosed in German Laid-Open Application DOS No. 
2,434,816. 
Polyamidoamines which are employed in the process according to the 
invention are obtained when dicarboxylic acids of 4 to 10 carbon atoms are 
reacted with polyalkylenepolyamines which contain 3-10 basic nitrogen 
atoms in the molecule. Examples of suitable dicarboxylic acids are 
succinic acid, maleic acid, adipic acid, glutaric acid, suberic acid, 
sebacic acid and terephthalic acid. Mixtures of dicarboxylic acids may 
also be used to prepare the polyamidoamines, eg. mixtures of adipic acid 
and glutaric acid, or of maleic acid and adipic acid. The use of adipic 
acid is preferred. The carboxylic acids are condensed with 
polyalkylenepolyamines which contain 3-10 basic nitrogen atoms in the 
molecule, eg. diethylenetriamine, triethylenetetramine, 
tetraethylenepentamine, dipropylenetriamine, tripropylenetetramine, 
dihexamethylenetriamine, aminopropylethylenediamine and 
bis-aminopropylethylenediamine. The polyalkylenepolyamines may be employed 
either in the pure form or as mixtures with one another and/or with up to 
10% by weight of a diamine, eg. ethylenediamine or hexamethylenediamine. 
The reaction of the dicarboxylic acids with the polyalkylenepolyamines is 
preferably carried out in the absence of a solvent, but may also be 
carried out in a solvent which is inert toward these compounds. To effect 
the reaction, the reactants are heated at an elevated temperature, eg. at 
from 120.degree. to 180.degree. C., and the water of reaction is removed 
from the system. However, the condensation may also be carried out in the 
presence of lactones or lactams of carboxylic acids of 4 to 8 carbon 
atoms. Such compounds then become incorporated, as condensed units, into 
the polyamidoamine. From 0.8 to 1.4 moles of polyalkylenepolyamine are 
employed per mole of dicarboxylic acid. 
The polyamidoamines can be reacted direct with the difunctional 
crosslinking agents to give nitrogen-containing condensates. However, 
particularly effective retention agents and drainage aids are obtained if, 
prior to the reaction with the difunctional crosslinking agents, the 
polyamidoamines are modified with from 2 to 8 ethyleneimine units per 
basic nitrogen (ie. 100 parts by weight of a polyamidoamine are reacted 
with from 20 to 400 parts by weight of ethyleneimine). Products of this 
nature are obtained by grafting ethyleneimine onto the polyamidoamine in 
the presence of an acid or Lewis acid, eg. boron trifluoride etherate or 
sulfuric acid. Compounds which generate an acid, such as dimethyl sulfate 
and alkyl halides, may also be used. 
The difunctional crosslinking agents used according to the invention are 
.alpha.,.omega.-dihalopolyglycol ethers derived from polyglycol ethers 
containing 8-100 alkylene oxide units. Suitable polyalkylene oxides are, 
in the main, ethylene oxide homopolymers and ethylene oxide/propylene 
oxide copolymers, but the proportion of propylene oxide groups should 
advantageously be at most 50% of the total alkylene oxide groups. 
Preferably, block copolymers of the formula 
EQU A[(OR.sup.1).sub.m (OR.sup.2).sub.n (OR.sup.1).sub.p H].sub.2 
are used, where R.sup.1 is an ethylene radical, R.sup.2 is a 1,2-propylene 
radical, m and p have values from 1 to 50, n has a value from 0 to 50 and 
A is the radical of a dihydric alcohol of 2 to 6 carbon atoms or of 
propylene glycol or of a polypropylene glycol containing 2-50 propylene 
oxide units, n in the latter case being 0. Specific examples are 
oxyethylated and oxyethylated/oxypropylated dihydric alcohols, e.g. 
glycol, propylene glycol or hexanediol, and polypropylene glycol 
containing up to 50 propylene oxide units per molecule. Oxyethylation of 
the latter product at both ends results in blocks of ethylene oxide units, 
i.e. block copolymers containing blocks of ethylene oxide, propylene oxide 
and ethylene oxide. The products obtained by oxyethylation, with or 
without oxypropylation, are to be regarded as compounds possessing two 
terminal free hydroxyl groups. These terminal hydroxyl groups are then 
replaced by chlorine, by 
1. reaction with thionyl chloride, accompanied by elimination of HCl, 
followed by catalytic decomposition of the chlorosulfonated compound, with 
elimination of sulfur dioxide, or 
2. conversion to the corresponding bis-chlorocarbonic acid ester by 
reaction with phosgene, accompanied by elimination of HCl, following by 
catalytic decomposition, with elimination of carbon dioxide. In each case 
.alpha.,.omega.-dichloro-polyglycol ethers are obtained. The decomposition 
of the bis-chlorosulfonated compounds obtained by the first stage of 
method 1 and of the bis-chlorocarbonic acid esters formed in the first 
stage of method 2, to give .alpha.,.omega.-dichloro-polyalkylene oxides, 
is carried out by conventional methods, namely heating these compounds at 
about 70.degree.-150.degree. C. in the presence of up to 2% by weight of a 
tertiary amine. Only these two methods are suitable for the preparation of 
the .alpha.,.omega.-dichloro-polyglycol ethers, since they give the 
required crosslinking agents in sufficient purity that they can be used 
directly for the preparation of the nitrogen-containing condensates 
without first having to be subjected to an expensive purification 
operation. 
The polyamidoamines, which may or may not contain 2-8 grafted ethyleneimine 
units per basic nitrogen, are crosslinked with the 
.alpha.,.omega.-dichloropolyglycol ethers at above 20.degree. C. The 
crosslinking is carried out in a solvent. Suitable solvents are water and 
organic fluids which are water-miscible, for example monohydric and 
polyhydric alcohols, provided these are completely water-miscible, 
dioxane, tetrahydrofuran and etherified polyols, eg. monoethers of 
ethylene glycol, diethylene glycol and triethylene glycol with C.sub.1 
-C.sub.4 -alcohols, and the corresponding diethers, eg. diethylene glycol 
diethyl ether and diethylene glycol dibutyl ether. Of course, mixtures of 
several solvents may also be used. Preferably, the reaction is carried out 
in water. 
The conjoint concentration of the polyamidoamine and of the difunctional 
crosslinking agent in the solvent can vary within a wide range and can be, 
for example, from 80 to 10% by weight. If water is used as the sole 
solvent, the condensation reaction is as a rule carried out under 
atmospheric pressure at up to 100.degree. C. If the reaction is carried 
out in the absence of water or in the presence of only small amounts of 
water, and a solvent boiling below the condensation temperature is used, 
the condensation is carried out in a pressure apparatus. 
A suitable procedure for preparing the water-soluble, nitrogen-containing 
condensates is to mix the polyamidoamines, which may or may not contain 
grafted ethyleneimine units, and the difunctional crosslinking agents, and 
heat the mixture at an elevated temperature in order to bring about the 
crosslinking reaction. An alternative procedure is to introduce a portion 
of the polyamidoamine into a reaction vessel, heat this to the 
condensation temperature, and add the crosslinking agent at the rate at 
which it is consumed. Yet again, it is possible to introduce the 
.alpha.,.omega.-dichloropolyglycol ethers, used as difunctional 
crosslinking agents, into the reaction vessel, heat them to the 
condensation temperature and add the polyamidoamine, continuously or in 
portions, in accordance with the rate of the reaction. Depending on the 
reaction conditions, namely the temperature, the concentration of the 
reactants, and the solvent, the condensation reaction is complete after 
from about 30 minutes to 15 hours. The condensation is taken at least to 
the point that water-soluble, high molecular weight resins which have a 
viscosity, measured in 20% strength aqueous solution at 20.degree. C., of 
not less than 300 millipascal are obtained. Preferably, resins which have 
a viscosity of from 400 to 2,500 mPas in 20% strength aqueous solution at 
20.degree. C. are prepared. The course of the crosslinking reaction can 
easily be followed by taking samples of the reaction mixture and 
determining the viscosity of the resin solutions. 
The condensation reaction is carried out at a pH above 8, preferably at 
from 9 to 11. It can easily be stopped by reducing the pH to 7 or less. 
The crosslinking agents described in German Laid-Open Application DOS No. 
2,434,816 (.alpha.,107 -dichlorohydrin-polyalkylene glycol ethers) must, 
in the prior art process, be reacted completely since otherwise a further 
undesired increase in the viscosity of the condensates occurs. By 
contrast, it is not necessary, with the novel process, that the entire 
amount of the difunctional crosslinking agent 
(.alpha.,.omega.-dichloro-polyalkylene glycol) should be reacted with the 
polyamidoamine. Rather, storage-stable products are obtained even if 
residual unconverted .alpha.,.omega.-dichloropolyethylene glycol remains 
in the condensate, provided the pH of the aqueous solution of the reaction 
mixture is brought to 5 or less. The novel process has the advantage over 
the process disclosed in German Laid-Open Application DOS No. 2,434,816 
that the crosslinking reaction is more easily controllable, especially 
with sizeable batches, in particular by lowering the temperature and by 
reducing the pH. The proportion of the cross-linking agent which has not 
reacted with the polyamidoamine can be left in the condensate without 
thereby causing an undesired side-reaction. 
The nitrogen-containing condensates prepared as described are used as 
flocculating agents, retention agents and drainage aids in the manufacture 
of paper. If the condensation of the polyamidoamines with the difunctional 
crosslinking agents has been carried out in a water-miscible solvent, it 
is not necessary to remove this solvent; instead, the reaction mixture can 
be employed direct, or after dilution with water, in paper manufacture. 
The water-soluble, nitrogen-containing condensates are added to the stock 
in an amount of from 0.01 to 0.3% by weight, based on dry fiber. 
In the Examples parts and percentages are by weight unless stated 
otherwise. The products prepared according to the invention were tested as 
drainage aids and compared, in respect of these properties, with 
conventional drainage aids. The drainage acceleration was characterized in 
terms of the reduction in freeness, in .degree.SR. The Schopper-Riegler 
freeness was determined in accordance with the method of Leaflet 107 of 
the Verein der Zellstoff-und Papierchemiker und Ingenieure. All the 
viscosity data shown were determined on 20% strength by weight aqueous 
solutions at 20.degree. C. in a Haake rotary viscometer, using a shearing 
rate of 49 sec.sup.-1 in the viscosity range below 1,000 mPas and of 24.5 
sec.sup.-1 at viscosities above this. 
The filler retention was characterized in terms of the ash content of paper 
sheets which were prepared by means of a Rapid-Kothen apparatus, in 
accordance with Leaflet 108 of the Verein der Zellstoff-und Papierchemiker 
und Ingenieure. The paper whiteness was determined by means of a 
Zeiss-Elrepho instrument, filter R46R with and without UV excitation. The 
reflectance is shown in percent. 
Preparation of .alpha.,.omega.-dichloropolyglycol ethers 
1. The reaction of polyethylene glycols with phosgene, and cleavage of the 
bis-chloroformates 
(a) 900 parts of gaseous phosgene are introduced into 1772 parts of 
polyethylene glycol of mean molecular weight 600 over 4 hours at 
25.degree.-35.degree. C., with exclusion of moisture, and at a rate such 
that the phosgene refluxes. The reaction mixture is then kept at 
60.degree. C. for 1 hour, during which 200 parts of phosgene are 
introduced. Thereafter, the temperature is raised to 80.degree. C. in the 
course of a further hour. To remove excess phosgene, a dry stream of 
nitrogen (50 liters/hour) is then passed through the reaction mixture. 
2,166 parts of polyethylene glycol bis-chloroformate are obtained as a 
clear pale yellow liquid. 
This product is decomposed, to give the .alpha.,.omega.-dichloro compound 
by, for example, dissolving 4 parts of pyridine in 200 parts thereof and 
heating the solution at 120.degree.-125.degree. C. At this temperature, 
carbon dioxide is rapidly eliminated. 2,000 parts of the bis-chloroformate 
are introduced dropwise over 3 hours. When the elimination of CO.sub.2 has 
ceased, 1,966 g of .alpha.,.omega.-dichloro-polyglycol ether (mean 
molecular weight: 600) are obtained as a yellow to pale brown liquid. The 
yield is virtually quantitative and the difunctional crosslinking agent 
obtained is sufficiently pure to be used direct--without further 
purification--for the crosslinking of polyamidoamines. The chlorine 
content of the .alpha.,.omega.-dichloro-polyglycol ether is 11.3% 
(identical with the theoretical value). 
.alpha.,.omega.-Dichloro-polyglycol ethers derived from polyethylene 
glycols of molecular weight 
(b) 200 
(c) 400 
(d) 800 
(e) 1,000 and 
(f) 1,500 
were prepared in a similar manner. These reactions again gave a virtually 
quantitative yield of .alpha.,.omega.-dichloro-polyglycol ether, so that 
removal of impurities was unnecessary. 
2. Preparation of .alpha.,.omega.-dichloro-polyglycol ethers by reacting 
polyethylene glycols with thionyl chloride 
(a) 300 parts of a polyethylene glycol of mean molecular weight 1,500 is 
heated to 56.degree. C., with exclusion of moisture, and 80.9 parts of 
thionyl chloride are added over 45 minutes, with thorough mixing. The 
terminal OH groups of the polyethylene glycol react with the thionyl 
chloride, HCl being evolved. When all the thionyl chloride has been added, 
the reaction mixture is stirred for 18 hours at 40.degree. C., after which 
nitrogen is passed through the melt for 4 hours to remove the hydrochloric 
acid virtually completely from the reaction product. In order to convert 
the chlorosulfonated polyethylene glycol ether, thus obtained, to the 
corresponding .alpha.,.omega.-dichloro compound, 4 parts of pyridine are 
added to the chlorosulfonation product and the mixture is heated at 
120.degree.-130.degree. C. Sulfur dioxide is eliminated, and after its 
evolution has ceased the reaction mixture is kept at 120.degree. C. for a 
further 2 hours, and finally the residual sulfur dioxide is removed at 
this temperature under reduced pressure from a waterpump. On cooling the 
batch to room temperature, a pale yellow paste is obtained, which consists 
of the desired .alpha.,.omega.-dichloro-polyglycol ether (chlorine content 
of the reaction product 4.7%; theoretical value 4.62%). 
The .alpha.,.omega.-dichloro compounds of polyethylene glycols of mean 
molecular weight 
(b) 4,000 
(c) 6,000 
(d) 9,000 
and the .alpha.,.omega.-dichloro compounds of 
(e) polytetrahydrofuran of mean molecular weight 600 and 
(f) polypropylene glycol of mean molecular weight 800 were prepared in a 
similar manner. The difunctional crosslinking agents obtained from (b)-(f) 
were also sufficiently pure to be used direct for the preparation of 
crosslinked, water-soluble, nitrogen-containing condensates. Preparation 
of the polyamidoamine resin 1. 
A mixture of 530 parts of water, 667 parts of a mixture of 91.5% of 
diethylenetriamine and 8.5% of triethylenetetramine, and 925 parts of 
adipic acid is heated to 160.degree. C. in the course of 31/2 hours under 
nitrogen. Water is then distilled off at 160.degree. C. for 5 hours. 1,400 
parts of water are added to the resulting polyamidoamine whilst it is at 
130.degree. C., giving a 48.3% strength aqueous solution. This resin 
solution has a density of 1.095 g/cm.sup.3 and a viscosity of 320 mPas at 
25.degree. C. It contains 7.0% (based on 100% pure polyamidoamine) of 
basic nitrogen. Preparation of the polyamidoamine resin 2 
15.5 parts of concentrated sulfuric acid are added to 548.6 parts of a 
48.3% strength aqueous solution of polyamidoamine resin 1 (which solution 
accordingly contains 250 parts of the 100% pure resin 1), and the mixture 
is heated to 80.degree. C. 534 parts of a 50% strength aqueous 
ethyleneimine solution are then added over 4 hours at 
80.degree.-85.degree. C. After this addition, the reaction mixture is kept 
at 80.degree. C. for a further 30 minutes. A polyamidoamine modified with 
6.2 ethyleneimine units per basic nitrogen is obtained in the form of a 
47.1% strength aqueous solution which at 20.degree. C. has a density of 
1.094 g/cm.sup.3 and a viscosity of 753 mPas. Preparation of the 
polyamidoamine resin 3 
581 parts of adipic acid are added to 507 parts of an amine mixture of 9% 
by weight of ethylenediamine, 49% by weight of 
.gamma.-aminopropyl-ethylenediamine, 39% by weight of 
bis-(.gamma.-aminopropyl-ethylenediamine and 3% by weight of higher 
polyalkylenepolyamines in 250 parts of water at 60.degree.-80.degree., 
under nitrogen. The mixture is kept at 120.degree. for 2 hours, whilst 
distilling off the water, and the temperature of the residue is then 
raised to 160.degree.-170.degree. over 3 hours and kept at this level 
until the acid number has fallen to below 15 mg of KOH/g. 1,000 parts of 
water are rapidly added to the viscous resin at 130.degree. C. and the 
mixture is cooled to room temperature. 
The aqueous pale brown resin solution has the following characteristics: 
______________________________________ 
Solids content: 50.4% by weight 
Acid number: based on 100% 
0.279 milliequivalent/g 
Amine number: pure product 
4.82 milliequivalents/g 
Viscosity of a 45% strength aqueous 
resin solution at 20.degree. C.: 
567 mPas 
Refractive index of a 45% strength 
resin solution, n.sub.D.sup.20 : 
1.4242. 
______________________________________ 
Preparation of the polyamidoamine resin 4 
3.75 parts of 98% strength sulfuric acid are added to 500 parts of the 
aqueous solution, of about 50% strength, of the polyamidoamine resin 3 and 
the mixture is heated to 70.degree. C. 540 parts of a 50% strength aqueous 
ethyleneimine solution are run into this solution over about 3 hours, at 
about 80.degree. C. After all the ethyleneimine has been added, the 
reaction mixture is kept at 80.degree. C. for 1-2 hours, until 
ethyleneimine is no longer detectable in the reaction solution. The resin 
has the following characteristics: 
Solids content: 47.8% by weight 
Acid number: 0.11 milliequivalent/g 
Amine number: 10.27 milliequivalents/g 
Viscosity (of a 45% strength solution): 614 mPas (at 20.degree. C.)

EXAMPLE 1 
212.3 parts of the 47.1% strength aqueous solution of polyamidoamine resin 
2 were diluted to 25% strength and 116 parts of a 25% strength solution 
(equivalent to 29 parts of solid material) of the 
.alpha.,.omega.-dichloro-polyethylene glycol ether obtained by reacting a 
polyethylene glycol having a molecular weight of 1,500 with phosgene 
followed by cleavage of the bischloroformates (as previously described) 
were added at 85.degree. C. This means that, expressed in terms of the 
pure materials, 0.29 part of crosslinking agent was used per part of 
polyamidoamine. The crosslinking reaction was complete after 5.8 hours at 
85.degree. C. The reaction was stopped by adding 28 parts of formic acid, 
whereby the pH of the reaction mixture was reduced to 7.5. The mixture was 
then diluted to an active substance content of 20% by adding water. The 
viscosity of this diluted mixture was 800 mPas. 
EXAMPLE 2 
31 parts of a 25% strength aqueous solution of the 
.alpha.,.omega.-dichloro-polyglycol ether 1(f) were added to 100 parts of 
a 25% strength aqueous solution of polyamidoamine resin 2 and the mixture 
was heated to 85.degree. C., with thorough mixing. The viscosity of the 
reaction mixture was monitored by taking samples at intervals of 10 
minutes, preparing 20% strength aqueous solutions of these and determining 
the viscosity at 20.degree. C. After condensing the mixture for 5.2 hours 
at 85.degree.-90.degree. C., the viscosity of a sample of the reaction 
mixture in 20% strength aqueous solution at 20.degree. C. was 800 mPas. 
The pH of the solution was reduced to 8 by adding formic acid. The 
reaction mixture was cooled to room temperature and diluted to an active 
substance content of 20% by adding water. 
COMATIVE EXAMPLE 1 
The procedure described in Example 1 was followed except that the 
difunctional crosslinking agent used was the .alpha.,.omega.-di-(propylene 
chlorohydrin)-polyethylene glycol ether obtained by reacting 1 mole of 
polyethylene glycol of molecular weight 1,500 with 2.05 moles of 
epichlorohydrin, in accordance with German Laid-Open Application DOS No. 
2,434,816. The crosslinking temperature was 65.degree. C. This means that 
0.23 part of 100% pure di-(propylene chlorohydrin)-polyethylene glycol 
ether was employed per part by weight of the 100% pure polyamidoamine. 
After condensing the reaction mixture for 4.5 hours, the pH was brought to 
8 by adding formic acid and the solution was diluted to a 20% content of 
active substance. The viscosity of this 20% strength aqueous solution was 
420 mPas at 20.degree. C. 
EXAMPLE 3 
207 parts of the 48.3% strength aqueous solution of polyamidoamine resin 1 
were diluted to a 25% strength aqueous solution, which was heated to 
85.degree. C.; at this temperature, a 25% strength aqueous solution of the 
.alpha.,.omega.-dichloro-polyethylene glycol ether 2(a) was added slowly. 
The addition was continued until the viscosity of a 20% strength aqueous 
solution at 20.degree. C. was 800 mPas. This required 38.5 parts of the 
difunctional crosslinking agent 2(a), calculated as 100% strength active 
substance, namely 154 parts of the 25% strength aqueous solution. 
Accordingly, 0.385 part of 100% pure .alpha.,.omega.-dichloro compound was 
employed per part of 100% pure polyamidoamine. When the desired viscosity 
had been reached, the condensation was stopped by adding formic acid; a pH 
of 8 was found to be sufficiently low for this purpose. The reaction 
mixture was then diluted to an active substance content of 20%. 
COMATIVE EXAMPLE 2 
The procedure described in Example 3 was followed, except that the 
difunctional crosslinking agent used was the di-(propylene chlorohydrin) 
of polyethylene glycol ether having a molecular weight of 1,500 
(crosslinking agent according to German Laid-Open Application DOS No. 
2,434,816). The crosslinking temperature was 65.degree. C. 42.5 parts by 
weight of the 100% pure crosslinking agent were required per 100 parts by 
weight of pure polyamidoamine to give a viscosity of 800 mPas, measured on 
a 20% strength aqueous solution of the crosslinked polyamidoamine, at 
20.degree. C. The pH of the resin solution was brought to 8 by adding 
formic acid, and the mixture was then diluted to an active substance 
content of 20%. 
EXAMPLE 4 
603.2 parts of the 47.75% strength polyamidoamine resin 4 were diluted with 
596.8 parts of water and the mixture was heated to 90.degree. C. For 
crosslinking, 330 parts of a 20% strength aqueous solution of a 
polyether-dichloride (crosslinking agent 1f) obtained by phosgenating a 
polyethylene glycol of molecular weight 1,500 were added. The 100% pure 
crosslinking agent had the following characteristics: 
Chloride content: 0.023 milliequivalent/g 
Total chlorine: 1.38 milliequivalents/g 
Volatiles: 0.3% 
After 23/4 hours, the viscosity of the resin showed no further rise; a 
further 28 parts of cross-linking agent solution 1(f) were then added. In 
the course of a further 31/2 hours, the viscosity of the resin rose to 
1,719 mPas, measured at 20.degree. C. The resin was cooled to room 
temperature, brought to a pH of 9.0 with 71.5 parts of 85% strength formic 
acid, and diluted with water to an active substance content of 20%. This 
resin solution had a viscosity of 1,043 mPas, measured on a Haake rotary 
viscometer at 20.degree. C. 
EXAMPLE 5 
603.2 parts of the 47.75% strength polyamidoamine resin 4 were diluted with 
596.8 parts of water and 462 parts of a 20% strength aqueous solution of 
the polyether-dichloride 1(f) were added at 90.degree. C. The reaction 
mixture was kept at the same temperature until the resin solution had 
reached a viscosity of 1,500 mPas, measured at 20.degree. C.; this 
required 170 minutes. The reaction was then stopped by neutralizing to pH 
7 with formic acid, and the mixture was cooled to room temperature. It was 
stabilized by acidifying to pH 4.0 with 85% strength formic acid, the 
total amount required being 199 parts. When diluted with water to 20% 
content of active substance the resin solution had a viscosity of 1,105 
mPas at 20.degree. C. 
COMATIVE EXAMPLE 3 
337 parts of the 47.8% strength aqueous polyamidoamine resin solution 4 
were diluted to 24% active substance content with 334 parts of water; the 
mixture was heated to 70.degree. C. and 192 parts of a 24% strength 
aqueous crosslinking agent solution were added. The crosslinking agent 
used was a reaction product prepared from 1 mole of polyethylene glycol of 
mean molecular weight 1,500 and 2.05 moles of epichlorohydrin, in the 
presence of boron trifluoride. The condensation at 70.degree. C. was 
continued until no further increase in viscosity of the reaction mixture 
was detectable; a further 3 portions (48,14 and 8 parts respectively) of 
the 24% strength crosslinking agent solution were then added, to produce 
further crosslinking, until the viscosity of the resin ultimately reached 
1,530 mPas at 20.degree. C. The resin was then brought to pH 8.0 with 85% 
strength formic acid and was diluted with water to 20% content of active 
substance. This 20% strength aqueous resin solution had a viscosity of 675 
mPas at 20.degree. C. 
Use of the resins prepared in Examples 1 to 5 and Comparative Examples 1 to 
3 
First, the drainage acceleration was tested. The stock used was newsprint, 
which was pulped in an Ultraturrax apparatus until speck-free. Two 
different pH values, and various amounts of materials, were used. The 
stock consistency was 0.24 g/l. The results obtained are summarized in 
Table 1. 
TABLE 1 
______________________________________ 
Drainage acceleration 
pH 4.8 
(1.5% of Effect on paper 
alum added 
whiteness and on 
to the the efficiency 
pH 7.3 stock) of opitcal brighteners 
______________________________________ 
100% pure 
0.06 0.08 0.05 0.09 with without 
resin added UV 88.7% 
UV 84.2% 
(% based on 
dry pulp) 
.degree.SR 
Blank value 
76 70 
(without 
added resin) 
Resin from 
52 50 40 36 81.5% 78.5% 
Comparative 
Example 1 
Example 1 
50 48 38 35 81.8% 78.8% 
Example 2 
50 48.5 38.5 35 81.9% 78.9% 
______________________________________ 
The filler retention for different amounts of resin added to the stock was 
also determined. The results are summarized in Table 2. 
TABLE 2 
______________________________________ 
pH of the fiber suspension: 
6 4.8 
Filler retention 
(% ash in the paper) 
Alum added, based 0.5 1.5 
on pulp plus filler 
Blank value 2.2 2.4 
Comparative Example 1 
0.015% added 
4.9 5.0 
0.03% added 
7.0 6.3 
Example 1 0.015% added 
5.3 5.1 
0.03% added 
6.7 5.9 
Example 2 0.015% added 
5.5 5.0 
0.03% added 
6.8 6.0 
______________________________________ 
To test the drainage acceleration produced by the resin from Example 3 and 
from Comparative Example 2, newsprint was pulped in an Ultraturrax 
apparatus until speck-free. The stock consistency was 0.24 g/l. The 
following values were found. 
TABLE 3 
______________________________________ 
pH 4.8 
(1.5% of alum 
added to the 
pH 7.3 stock) 
______________________________________ 
100% pure resin added, 
0.06 0.08 0.06 0.09 
% based on dry pulp 
Blank value (without 
76.5 68 
added resin) 
Comparative Example 2 
69 58 52 49 
Example 3 67 56 50 45 
______________________________________ 
In testing the filler retention, the values shown in Table 4 were obtained. 
TABLE 4 
______________________________________ 
pH of the fiber 6 4.8 
suspension 
Alum added, based on 0.5 1.5% 
pulp plus filler 
Blank value 2.1 2.4 
Comparative Example 1 
0.015% added 
4.1 5.5 
0.03% added 
6.3 6.5 % ash in 
Example 3 0.015% added 
4.6 5.6 the paper 
0.03% added 
6.5 6.5 
______________________________________ 
The effect of the resins on the paper whiteness was found to be as follows: 
TABLE 5 
______________________________________ 
Sample from Com- 
Sample from 
parative Example 2 
Example 3 
______________________________________ 
With UV 95.8% 90.6% 90.0% 
Without UV 88.9% 
88.8% 88.7% 
______________________________________ 
The drainage acceleration produced by the resins from Examples 4 and 5 and 
from Comparative Example 3 was tested by adding the resins to a stock of 
newsprint, which had been pulped until speck-free, at a stock consistency 
of 0.24 g/liter and a neutral or slightly acid pH. The following results 
were obtained: 
TABLE 6 
______________________________________ 
Drainage acceleration 
pH 4.8 
(4.5% of alum 
added to the 
Neutral stock) 
______________________________________ 
100% pure resin added 
0.06 0.08 0.12 0.03 0.06 0.09 
(% based on dry pulp) 
.degree.SR .degree.SR 
Blank value (without 
63 58.5 
added resin) 
Comparative Example 3 
42 37 33 47.5 45.5 43 
Example 4 40 37 33 44.5 41.5 40 
Example 5 41 38 34 46 44 42.5 
______________________________________ 
The filler retention was determined by measuring the ash content of paper 
sheets which had been produced, in the presence of the resins, on a 
Rapid-Kothen apparatus (Leaflet 108 of the Verein der Zellstoff-und 
Papierchemiker und-Ingenieure). The following values were found: 
TABLE 7 
______________________________________ 
Stock: 80% bleached sulfite cellulose (35 .degree.SR) plus 20% of China 
clay 
Stock consistency: 2 g/liter 
pH 6; pH 4.5; 
0.4% of alum 1.4% of alum 
100% pure resin added 
0.015 0.030 0.045 
0.015 
0.030 
0.045 
(% based on dry pulp) 
% ash 
Blank value 4.0 2.9 
(without added resin) 
Comparative Example 3 
8.2 8.8 9.2 6.6 7.2 7.8 
Example 4 7.8 8.8 9.1 6.7 7.9 8.3 
Example 5 7.8 8.9 9.2 6.6 7.1 7.8 
______________________________________