CA1129142A - Anti-flooding agent for paints and plasters - Google Patents

Abstract

Hoe 77/K 020 (K 2544) ANTI-FLOODING AGENT FOR PAINTS AND PLASTERS

Abstract of the Disclosure This invention relates to an agent for preventing the flood-ing of color pigments in aqueous plastic dispersion paints, plastic-based plasters, and distemper paints containing cellulose ethers, which is based on a block polymer in which a di- or polyamine is present as the initial molecule on which alkylene oxide units are added, said block polymer being obtained from one mole of a di-or polyamine of the general Formula I

Description

l~Z91~Z Hoe 77/K 020 (K 2544) The present inventlon relates to an agent which prevents the flooding of color pigments contained ln aqueous, cellulose ether-containing plastic dispersion paints, distemper palnts, or plastic-based plasters. Further, the inventlon relates to a paint or plas-ter containing the agent.
If white plastic dispersion paints, dlstemper paints or plastic-based plasters which contain cellulose ethers are to be colored, lt is often impossible, despite careful stirring, to work the commercially available concentrated pigment pastes used for this purpose into the paints with the desired degree of uniformity.
This undesirable effect, which is not recognizable during mixing of the components, normally becomes apparent only when the paints or plasters are spread, rolled on, or otherwise applied to a sup-port, such as a wall or -wallpaper, in that the resulting color shade is non-homogeneous. The variations in the color shade are more or less lntensive, depending upon the frictional forces occurring during application of the paints or plasters. The treated surfaces dlsplay an uneven, blotchy color shade. Thls normally undesir-able effect is designated in the technical terminology as "rub-out"
or "flooding" of the pigments.
Numerous additives, mostly surface-active anionlc, cationic, or non-lonlc substances, have been dlsclosed and/or are being offered on the market whlch allegedly prevent such flooding.
Nevertheless, the consumer still encounters often insurmountable difficulties because the known substances are, for example, effective in some cases only, or must be added in relatively high quantities so that they adversely affect certain desirable properties Hoe 77/K 020 (K 2544) of the palnt or plaster, or cause a marked reduction of the water-reslstance of the dry paint or plaster.
The pigment pastes disclosed in German Auslegeschrift No.
1,165,544, contain substances which are soluble in water, benzene or benzine and whlch may be obtained by causing propylene oxide to act upon water-soluble aliphatic compounds with less than 8 carbon atoms which contain at least one active hydrogen atom.
Suitable aliphatic compounds are monohydric and polyhydric alco-hols, partlal ethers of polyhydric alcohols, amines and alkylol amines. It is stated in the German Auslegeschrift that the pigment pastes prepared in this manner do not tend to foam and can be very finely distributed by stirring or kneading them in the usual medla, of which water and several organic solvents are mentioned.
From German Auslegeschrift No. 2,156,603, or U. S. Patent No . 3,841,888, aqueous pigment dispersions are known which allegedly do not flocculate ln plastic dispersions containing cellu-lose ethers or dlstemper paints. Such aqueous pigment dlspersions contain from 20 to 55 per cent by weight of finely dlvided pigment, 5 to 25 per cent by weight of a surface active agent or a mixture of surface actlve agents, and 40 to 75 per cent by welght of water or a mixture of water and water-retaining substances. The surface actlve substance s are products of a reaction between certain ali-phatic dlamines or polyamlnes, or aromatic or cycloaliphatlc dla-mines, w1th 3 to 50 moles of propylene oxide and a subsequent reaction wlth 2 to 70 moles of ethylene oxide (the molar quantities refer to the equivalent of reactive amino hydrogen), the proportion of termlnal polyethylene oxlde blocks ranging from 40 to 80 per Hoe 77/K 020 (K 2544)

2`

cent by welght. The coloring of aqueous, blnder-containlng whlte plgment paints containing cellulose ethers ls stated as the preferred fleld of appllcation of these plgment dlspersions.
Besldes the customary additlves, the aqueous pigment dls-perslon disclosed in German Patent No. 2 ,414 ,455, contains pig-ments, condensation products of naphthalene, formaldehyde and sulfuric acid, ethylene oxide adducts to long-chain amines, and polymerization products of ethylene oxide and propylene oxide wlth terminal polyethylene oxide blocks. In the form of a pigment paste, this aqueous plgment dispersion allegedly shows good flow-lng behavior, no re-agglomeratlon of the pigment particles, no formatlon of lumps, and thus no reduction of the color intensity.
A pigment composltlon prepared in this manner is said to be par-ticularly suitable, for example, for colorlng aqueous paints based on plastlc dlspersions, and especially for coloring wallpaper paints based on plastic disperslons and cellulose derivatives.
German Offenlegungsschrlft No. 2,500,865, teaches a pro-cess for the preparation of a dry, water-dispersible pigment com-posltion which comprlses the following steps: a) mixing a pigment wlth water and 15 to 45 per cent (based on the weight of the pig-ment) of a non-ionlc dlspersing agent, 10 to 70 per cent of a water-disperslble, non-lonlc polymer, and, if desired, up to 40 per cent of a non-lonic colloid, and b) removing the-water from the mixture until a dry mass of a certain composition is obtained. The following compounds are listed as suitable non-ionic dispersing agents: polyether alcohols, alkylene oxide/alkylene diamine block polymers and polyoxy ethyleneglycol or glycerol esters, the block H oe 7 7/K 0 2 0 (K 2 5 4 4 ) polymers being obtained by addltlon of propylene oxide to ethylene diamine and subsequent addition of ethylene oxide. The following compounds are listed among the non-ionic polymers: at least par-tially hydrogenated vinyl acetate polymers or their ether derivatlves, N-vinyl pyrrolidone polymers and their copolymers with other vinyl compounds. Cellulose ethers, starches and starch derivatives, natural reslns etc. are said to be useful as non-ionic colloids.
The pigment mass prepared in this manner allegedly disperses easily in water, is compatible with latex systems and other aqueous sys-tems and shows good resistance to flocculation.
In addition to the above listed auxiliaries, further so-called "anti-flooding agents " are known, for example from E . Karsten:
"Lackrohstofftabellen" (Table of Raw Materials for Paints), 6th Editlon, Curt R. Vincentz Verlag, Hanover, 1976, some of which are expres sly intended for systems which may be dlluted with water and for systems to be dlluted with solvents and water. Practical experience has shown, however, that heretofore no agents havlng such an effect could be found, especially those whlch in the field of- cellulose ether-containing plastic dispersions, plastic-based plas-ters and dlstemper paints prevent the flooding of the color pig-ments or pigment pastes added in as many cases as possible.
This applies not only to the precautionary treatment of the colored dispersion mixture to be prepared, but especially to a subsequent treatment of such readily prepared colored dispersion mixtures which during practical use, for example during their application to a wall or wallpaper, exhlbit flooding of the color pigments.

It is thus the object of the present invention to provide an anti-flooding agent for pigments which is superior to the agents known from the prior art.
The present invention is an improvement over an agent for prevent-ing the flooding of color pigments in aqueous, cellulose ether-containing plastic dispersion paints, plastic-based plasters, and distemper paints, the agent being based on a block polymer in which a di- or polyamine is present as the initial molecule on which alkylene oxide units are added.
According to one aspect of the present invention there is provided a process for preventing the flooding of color pigments in aqueous plastic dispersion paints, plastic-based plasters, and distemper paints containing cellulose ethers, in which an agent is added, which is based on a block poly-mer in which a di- or polyamine is present as the initial molecule on which alkylene oxide units are added, said block polymer being obtained from one mole of a di- or polyamine of the general formula I

H2N - (R ~ N)x ~ H (I) wherein R is an alkylene group with 2 to 6 carbon atoms, and x is a whole number from 1 to 4, by reaction with about 5 to 50 moles of ethylene oxide, followed by reaction with about 5 to 100 moles of propylene oxide.
According to another aspect of the present invention there is pro-vided an aqueous, binder-containing paint or plaster containing a cellulose ether, which is either colored or is to be colored and which is white as long as no color pigment has been added, and containing an agent which is based on a block polymer in which a di- or polyamine is present as the initial molecule on which alkylene oxide units are added, said block polymer being obtained from one mole of a di- or polyamine of the general formula I
H
~2N - (R ~ N)x ~ H (I) wherein R is an alkylene group with 2 to 6 carbon atoms, and x is a whole number from 1 to 4, by reaction with about 5 to 50 moles of ethylene oxide, Z

followed by reaction with about 5 to 100 moles of propylene oxide.
Suitable diamines or polyamines according to general Formula I, from which the block polymers used according to the invention may be prepared, are, for example: propylene diamine-1,3,butylene-diamine-1,4, diethylenetri-amine, dipropylenetriamine, triethylenetetramine, tetraethylenepentamine, and, preferably, ethylenediamine-1,2. According to the method disclosed in German Offenlegungsschrift No. 2,165,586, first only a relatively small B -5a-L4Z Hoe 77/K 020 (K 2544) quantlty of ethylene oxlde ls used per mole of the amines of Formula I to saturate the hydrogen atoms attached to the nitrogen.
Then, the alcoholic hydroxyl groups present in the thus synthe-slzed molecules are alkalized, for example by the actlon of sodlum methylate, and the resultlng product is then reacted with further quantitles of ethylene oxide untll the desired quantlties of ethylene oxide have been incorporated. Finally, propylene oxide ls added untll the end product has the desired molecular weight.
The block polymers or graft polymers prepared in thls manner may correspond, for example, to the following general Formula II:
(C2H40)a - (C3H6)b3 H(OC3H6)b --(C2H4)a~ ¦ (II) N-(R-N)X-(c2H4o)a4-(c3H6 )b4 H(OC3H6)b (C2 4)a2 wherein each of the indices a1 to a stands for a whole number um (a1+a2+a3+a4) = 5 to 50, preferably 10 to 40 and each of the lndices b1 to b4 stands for a whole number and the sum (b1+b2+b3+b4) = 5 to 100, preferably 40 to 70, whlle R and x have the meanings stated above.
- Aqueous plastic dlspersion palnts, plastlc-based plasters , and dlstemper paints are normally avallable in the white state.
Thelr composltion may be taken from DIN 18,363 entitled:
"Anstrlcharbelten" (Palntlng Jobs) of September 1976: plastic dis-perslon paints contain plastic dlspersions, pigments (normally white plgments, such as tltanium dloxide, llthophones, or chalk), fillers (such as calclum carbonates, powdered quartz, barlum sulfate, 42 Hoe 77/K 020 (K 2544) flbrous materials, and granulates), and auxlllarles, e.g. fungl-cldes; they may be either fluld or pasty and are subdivided, according to thelr composltlon, irlto the followlng groups: washing-resistant, abraslon-reslstant, and weather-resistant.
PLastic-based plasters are distinguished from plastlc dis-persion palnts ln that they contaln flllers which impart a certaln structure to them. Distemper palnts contain sizes, pigments (normally white pigments), and fillers, e.g. flbrous materials.
Plastlc disperslons lnclude many of the dlsperslons of fllm-forming homo- or copolymers of acryllc acld esters, methacrylic acid esters, acryllc and methacryllc acids, styrene, ethylene, butadi-ene, acrylonltrlle, vlnyl acetate, vlnyl proplonate, vinyl esters of long-chaln branched carboxyllc aclds, or maleic acld esters.
Sultable slzes are binders in general, such as water- soluble cellulose ethers, starch, dextrln, vegetable glue s, bone glue, and other anlmal glues. Besldes surface-actlve substances, water-soluble cellulose ethers, such as methyl cellulose, methyl hydroxy-alkyl cellulose, carboxymethyl cellulose, hydroxy ethyl cellulose, or mlxtures thereof, are added to the palnts or pla sters in order to lmprove thelr water-retentlon capaclty, thelr processlng charac-terlstlcs, and thelr adheslon.
The above dlscussed drawbacks may become apparent when the different dlsperse systems, vlz. white palnt or plaster on the one hand and colored pigment component on the other hand, are combined wlth each other, 1. e . when the white paints or plasters are colored.
As a rule, the colored plgment pastes normally used for colorlng whlte palnts or plasters contaln, in addltlon to an Hoe 77/K 020 (K 2544) inorgarilc or organlc pigment, a tenside, an organic solvent, and/or water, and a preservative. Sultable lnorganlc plgments are, for example, carbon black, zinc sulfldes, cadmlum sulfides, ultra-marine, iron oxldes, nickel yellow or chromotitanium yellow, cobalt blue, chromium oxides, or chromates. Among the organic plgments, for example those of the azo, anthraquinone, azapor-phine, thlolndigo, quinacridone, dioxazine, naphthalene-tetracar-boxylic acld, perylene-tetracarboxylic acid, or phthalocyanine serle s are preferred .
The agent used accordlng to the inventlon to prevent the "rub-out" of colored plgments may be added to the aqueous palnts or plasters containing cellulose ethers and blnders, especlally to plastlc disperslon palnts, plastic-based plasters, and distemper palnts, elther whlle the paint or plaster ls still in the whlte state, by the manufacturer, converter or consumer, or after the palnt or plaster has been colored by the addition of a colored pigment, by the converter or consumer. Thls latter posslbillty is of partlcular lmportance because ln this manner already spoiled compositlons, 1. e . those dlsplaylng floodlng when no agent ls added to them, 2 0 may be returned to thelr useful state . In addltlon to the preferred posslbilltles of appllcatlon mentloned above, it is also posslble to add the agent accordlng to the lnvention dlrectly to the colored plgment paste . Advantageously, about 0.1 to 2 . 0 per cent by weight (calculated on the weight of the colored palnt or plaster) of the agent according to the inventlon are added; in many cases, an addltion of about 0 . 2 to 0 . 5 per cent by weight is sufficient .
The advantages achieved by the agent according to the in-ventlon are malnly the followlng:

2 Hoe 77/K 020 (K 2544) - The agent according to the invention may be generally added to paints or plasters at all stages of their prepa-ration and is not limlted to the use with one class or some classes of color pigments.
- The agent according to the invention does not tend to foam, or foams only slightly, so that the frequently occurring foaming during intensive agitation of the paints or plasters is not increased at all or is only inslgnifi-cantly increased.
- The agent according to the invention is capable of be-coming effective without the action of strong shear forces, so that mixing it with the paint or plaster at a low rate of revolution of the dissolver or even by hand will be sufflcient .
- The influence of the agent according to the invention on the water-resistance of the paints or plasters is within tolerable limits.
Some of the terms used above may be taken from DIN
55 ,945 entitled: "Anstrlchstoffe und ahnliche Beschichtungsstoffe"
(Paints and Coatings) of October 1973. The term "Ausschwimmen"
(flooding), for example, deslgnates the vlslble separation of the pigments contained ln the paint or plaster during storage or while the applied paint drles. A "Bindemittel" (binder) is the non-volatlle component of the paint or plaster, without pigment and filler, but includlng plasticizers, desiccants, and other non-volatlle auxiliaries; the binder connects the pigment particles with each other and wlth the base and thus forms the finlshed coatlng wlth the m .

3L42 Hoe 77/K 020 (K 2544) DIN 53,778, which is mentioned in the following examples, deals, in part 2 of September 1976, with plastic dispersion paints for lndoor use and ways of determining the cleanability of paint coatings and their resistance to washing and abrasion. The wash-ing and abraslon resistance of the dispersion paint coating which is to be determined ls its property to exhibit not more than a cer-taln predetermlned abrasion when it is subjected to a predetermined period of abrasive stress in a defined abrasion tester.
The color pigment used in all of the following examples is known to present serious flooding problems to the converter or con~
sumer. Therefore, the quantities of the inventive anti-flooding agent which are added in the examples are not representative for the quantitles to be used when processing most of the other color plgments or pigment pastes. The quantities added ln the examples are very high; in most other cases, lower quantities will be sufflclent .
All percentages are by welght.
Example 1 A white dlsperslon palnt for lndoor use (washlng-reslstant accordlng to DIN 53, 778) of the following compositlon:
170 p. b . w . of water, 10 p.b.w. of a 10% aqueous solution of Na-polyphosphate, 5 p . b . w . of an NH4 salt of a polyacryllc acid, as the dlspersing agent, l p.b.w. of a preservatlve (bacterlcide), 1 p.b.w. of a 10% aqueous NaOH solutlon, 75 p.b.w. of tltanlum dloxide, Hoe 77/K 020 (K 2544) ~'~ P~L42 400 p.b.w. of crystalline CaCO3, 50 p.b.w. of amorphous CaCO3 (chemlcally precipltated), 25 p .b. w . of kaolin (aluminum sllicate), 1 p.b.w. of an anti-foaming agent, 160 p.b.w. of methyl hydroxyethyl cellulose in a 2.5 per cent aqueous solution (medium viscosity of a 2% aqueous solution at 20 C = 6, 000 cP), 90 p.b.w. of a styrene-acrylate copolymer disperslon, and 7 p.b.w. of butyl-diglycol acetate, as a film-forming ad~uvan t, ls manually mixed, by means of a spatula, with 2% by weight (based on the weight of the above composition) of a colored pig-ment paste composed of 25 per cent of di-oxazine(carbazole)-vlolet (Color Index No. 51,319), 13 per cent of a tenside, 46.3 per cent of ethyleneglycol monoethyl ether, 15 per cent of distilled water, and 0 . 7 per cent of sodium-pentachlorophenol as a preservative .
The vlolet pigment contained ln the mixture is present in the floc-- culated, i . e . flooded, state . Two batches of this non-homogeneous mlxture are prepared and from each batch 50 g are remo~ed and mixed, one wlth 0 . 5 g (= 1% of the weight of the colored dispersion paint) and the other with 0 . 75 g (= 1 . 5% of the welght of the colored dlspersion palnt) of a block polymer prepared from the following components: 1 mole of ethylene diamine, about 30 moles of ethylene oxide, and about 60 moles of propylene oxlde. The block polymer may be prepared as follows:

Z Hoe 77/K 020 (K 2544) A mixture of 14.4 p . b . w . of an 80 per cent aqueous ethyl-ene diamine solutlon and 0.13 p.b.w . of an 80 per cent aqueous hydrazine hydrate solution (to improve the color shade) is treated at 70C with 42.7 p.b.w. of gaseous ethylene oxide. The result-ing intermedlate product has an overall nitrogen content of 9.35 per cent, the proportion of tertiary nitrogen being 99/0. The inter-mediate product is alkalized by adding 14.4 parts by volume (the relation between parts by volume and parts by weight being the same as between liters and kilograms) of a sodium methylate solu-tion with a sodium content of 12.8 per cent. The formation of the alcoholate is completed by 5 hours' drying. 25.7 p.b.w. of the alkalized intermediate product are reacted with 22.7 p .b .w. of ethylene oxide at 120 - 130C; the addition product of ethylene diamine and ethylene oxide thus produced has an overall nitrogen content of 2.08%, corresponding to a molecular weight of 1345, and the proportion of ethylene oxide added is 29.2 moles. 28.5 p.b.w. of this lntermedlate product are reacted at 130-135C
with 71.5 p .b .w . of propylene oxide . The analysis of the reaction product shows an overall nitrogen content of 0.57%, which corre-sponds to a molecular weight of 4910 and a proportion of 61.4 moles of propylene oxide.
Samples are taken from the mixtures containlng the agent according to the invention and from the mixtures containing no such agent and are applied, by means of a hand-operated wiper, to test cards in a manner such that wet films of about 200~m thickness result. Before the films are dried, i.e. within 5 min-utes, an area of the wet film selected at random is thoroughly Z Hoe 77/K 020 (K 2544) spread by rubbing with the tip of the finger. After the films have dried, they are inspected in order to determine if the rubbed and the un-rubbed areas of the film are of identical color or if the color shades are different. The agent added is fully effective if the rubbed and the un-rubbed areas of the films are identical in color. By the addition of 1% of the agent according to the inven-tlon, the rub-out of the violet pigment - which is very considerable in the absence of such agent - is reduced to a weak flooding. If 1 . 5% of the agent according to the invention is added, the color shades are identical, i.e. the violet pigment does not separate.
Example 2 In order to investigate the influence of different quantities of the inventive agent on the abrasion resistance of the dispersion paints to wh~ch they are added, 0.75%, 1%, 1.5%, and 2% of the agent, based on the weight of the colored dispersion oaint, are added to the dlspersion palnt colored as in Example 1. When the abrasion resistance is tested in accordance with DIN 53,778, about 1200 cycles in an abrasion tester are achieved without the additlon of the agent and with an addition of 0.75%, l.e., a quantity which normally will be sufficlent in less difficult cases.
If 1% of the agent is added, the number of cycles ln the abrasion tester drops to about 930, with an addition of 1.5% to about 425 cycles, and at 2% to about 250 cycles.
ComParative Examples V1 to V19:
A vlolet dispersion paint is prepared as descrlbed in Exam-ple 1 and mixed, once wlth 1% and then wlth 1 . 5% of a known antl-floodlng agent. In none of the examples, ldentical color Hoe 77/K 020 (K 2544) shades are observed in the dlfferent areas of the test fllms, which means that the known agents, when applied ln quantlties compar-able to the quantities used of the lnventive agent, do not prevent the serious flooding of the violet pigment.
Table: Comparative Tests No . of Chemical Composition of Agent Added Published Test in:
V 1 block polymer of ethylene diamine, propylene DT-AS No.
oxide, and ethylene oxide with a proportion 2,156,603 of ethylene oxide of 40% -V 2 block polymer of ethylene diamine, propylene oxlde, and ethylene oxide with a proportion of ethylene oxide of 40% and a higher molecu-Lar weight than in V 1 V 3 block polymer of ethylene diamine, p~opylene oxlde, and ethylene oxide with a proportion of ethylene oxide of 40% and a higher molecular welght than in V 2 V 4 block polymer of ethylene diamine, propylene DT-OS No.
oxlde, and ethylene oxide with a proportion of 2,500,865 ethylene oxide of 10%
V 5 block polymer of ethylene diamine, propylene oxlde, and ethylene oxide wlth a proportion of ethylene oxide of 2 0%
V 6 naphthalene sulfonic acid/formaldehyde DT-PS No.
condensatlon product 2, 414,455 V 7 Na-alkyl-polyglycol ether sulfate with about ___ 2 moles of ethylene oxide V 8 Na-alkyl-polyglycol ether sulfate with about ___

3 moles of ethylene oxlde V 9 nonylphenol-oxethylate w1th about 8 to 30 DT-OS No.
moles of ethylene oxlde 2,500,865 V 10 cresol-nonylphenol-formaldehyde-oxethylate ___ V 11 trlbutylphenol-oxethylate wlth about 50 DT-OS No.
moles of ethyleneoxlde 2 ,500,865 V 12 oleyl fatty alcohol-oxethylate wlth about 8 to ¦ ~5 moles of ethylene oxlde 11 ~9:~L42 Hoe 77/K 020 (K 2544).

No. of Chemical Composition of Agent Added j Published T est in:

V 13 coconut fatty alcohol-oxethylate wlth about DT-OS No 8 to 25 moles of ethylene oxide 2,500,865 V 14 stearyl alcohol-oxethylate with about 15 to ..
25 moles of ethylene oxide V 15 I tallow fatty alcohol-oxethylate with about 11 ..
to 25 moles of ethylene oxide V 16 iso-tridecanol-oxethylate with about 8 to 15 ,.
. moles of ethylene oxide V 17 oleylamlno-oxethylate w1th about 5 to 25DT-PS No.
moles of ethylene oxlde 2 ,414,455 V 18 coconut fatty amlno-oxethylate with about 2 ..
to 25 moles of ethylene oxide V 19 Na-llgnin-sulfonate ___ It will be obvious to those skilled in the art that many modiflcations may be made within the scope of the present inven-tion without departing from the spirlt thereof, and the invention includes all such modifications.

Claims (5)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for preventing the flooding of color pigments in aqueous plastic dispersion paints, plastic-based plasters, and distemper paints con-taining cellulose ethers, in which an agent is added, which is based on a block polymer in which a di- or polyamine is present as the initial molecule on which alkylene oxide units are added, said block polymer being obtained from one mole of a di- or polyamine of the general formula I

(I) wherein R is an alkylene group with 2 to 6 carbon atoms, and x is a whole number from 1 to 4, by reaction with about 5 to 50 moles of ethylene oxide, followed by reaction with about 5 to 100 moles of propylene oxide.

2. A process according to claim 1 in which said block polymer is obtained from 1 mole of said amine and 10 to 40 moles of ethylene oxide and 40 to 70 moles of propylene oxide.

3. A process according to claim 1 in which ethylene diamine is used as the diamine.

4. An aqueous, binder-containing paint or plaster containing a cellu-lose ether, which is either colored or is to be colored and which is white as long as no color pigment has been added, and containing an agent which is based on a block polymer in which a di- or polyamine is present as the initial molecule on which alkylene oxide units are added, said block polymer being obtained from one mole of a di- or polyamine of the general formula I

(I) wherein R is an alkylene group with 2 to 6 carbon atoms, and x is a whole number from 1 to 4, by reaction with about 5 to 50 moles of ethylene oxide, followed by reaction with about 5 to 100 moles of propylene oxide.

5. A paint or plaster according to claim 4 containing about 0.1 to 2.0 per cent by weight of said agent, calculated on the weight of the paint or plaster in the colored state.