CA1051577A - Plastics dispersions comprising unsaturated halide copolymers reacted with ammonia, and process therefor - Google Patents

Abstract

PROCESS FOR THE MANUFACTURE OF PLASTICS DISPERSIONS

Abstract of the disclosure:
The wet adhesion of plastics dispersions and of paints made therewith is widely improved, if in the manufacture of the dispersions a nucleophilically substitutable .alpha.-.beta.-unsaturat-ed halogen compound in an amount of 0.5 to 10% by weight cal-culated on the total amount of monomers is copolymerized, and the dispersion so obtained is reacted with ammonia at a tempera-ture of at least 50°C.

Description

~ 5~ 5~
This inventlon relate~ to a p;roces~ for the manufacture of plastlcs di~persions ~uitable for m~king dispersion paints havi~g a good wet adheslon5 i.e. when wetted after drying.
The problem of the wet adhesion~ l.e. the adhe~io~ of dried paints on wetti~g, of dispersion ~aints on smooth non-absorbe~t surfaces has limited for a long time the use of such dispersion paints. Disp~rsion pai~ts having a low p~g-ment content, which dry on the substrate with ~ormation of a glo~y or ~lightly dull ~ilm~ have a poor adhesion to smooth non-absorbent surfaces whe~ the paints are rewetted after dry-ing. The wet adhesion is especially unsatisfactory with fresh palnt~ which ha~e ~ot yet undergone ageing.
Dispers~o~ paints o~ low pigment content are chosen when n washable coat of paint is desired. Owing to the high binder ;~
c:ontent o~ the pain~ a closed washable film ~s formed. Dis-perQion paints drying with formation of a glossy or sl~ghtly dull film al~o ha~e a concentration by volume o~ pigment of less than 40%, generally the concentrat~on is i~ the range of from about 10 to 2$%. They also contai~ about 3 to 15% of organic solve~t$ to improve the gloss and flowg to prolong the worklng time and for film consolidatlon, ~or example polyhydric alco-hols miscible with water a~d having up ~o 6 carbon atoms9 es-pecially ethylene and propylene glycol, or the monomethyl to monobutyl ethers thereo~. To impro~e the ~ilm consolidation solvents having a restricted solubility in water are used, such as the monoglycol ethers of carbo~ylic acids and more particularly esters of carboxyllc acids with monoalkyl ethers o~ glycol~ or oligoglycols~ Butyl diglycol a~etate i5 one of the most widely u~ed representatives of thls group. The com-binatlon of a low pigment content with a relati~ely high sol-

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: .... - - ~ . ~ .

5~
~nt content has a ~ery detrimental effe~t on the wet adhesion of the coats of disper~ion~ paint~.
With a poor wet adhesion pain-ts formulat~d to give wash-able coats do not ha~e this property whe~ applied to smooth 5 non absorbent surfaces~ ~or ex~mple old coats of alkyd or oil paint. I~ moist rooms, such as kitchen~ bath rooms, or in-dustrial places, where water of condensation may form~ the new coat may detach from the substrate if the wet adhesion is not sufficient. MoreoYer, a poor wet adheslon complicates paint-10 i~g. When, for example, the base and the upper half of a wall or the wall and the ceiling are to be painted in different colors, the first coat of paint may be ~oiled with the di~er-ent paint by slipping of the brush. In principle~ the dif-:Eerent paint could be wiped o~ with a wet cloth, but with a 15 poor wet adhesion the first paint msy then be damaged or e~en ?
removed simultaneously.
Thereforel many attempts ha~e b~e~ made to modify plastics di~per~ions i~ such a manner that the dispersion paints made therewith have the desired wet adhesion. X~ ~erman Offenle-Z gungsschrift 1,595,501 it has been proposed to prepare plastics dispersions by polymeriæing suitable monomers in aqueous emul-sion using as comonomers 0~2 to 15% by weight, calculated on the total amount of the monomer~, of compounds carrying oxi-rane groups and then to react the copolymer at room tempera-ture with ammo~ia or an amine. Suitable oxirane compounds, are,above all~ glycidyl esters of acrylic and methacrylic acid, all~l gl~cidyl ethers or ~lnyl glycidyl ether~.
Dispersion paints prepared with pls~tics di~per~lons o~
29 thi- type have quite a good wet adhesion, but ~or many appli~

cations the wet adhesion is not at all sufficient.
The present invention provides a process for the manufacture of a plastics dispersion suitable for making dispersion paints having a high wet adhesion, which comprises ~reating, at a temperature above 50C, a plastics dispersion obtained by copolymerizing in an aqueous medium olefinically unsaturated monomers with 0.5 to 10% by weight, calculated on the total amount of monomersJ of nucleophilically substitutable ~ -unsat-urated halogen compounds with two equivalents of ammonia for each equivalent of halogen compound and, in addition, an amount sufficient to give the hot dispersion a pH above 8, or reacting the plastics dispersion at a temperature above 50C with one mol hexamethylene tetramine for each mol halogen com-pound, and where required rendering the dispersion al~aline~by the addition of ammonia.
Ammonia can be added to the finished dispersion in the form of a gas, of a liquid, or a solution. It is preferably used in the form of a concentrated or dilute aqueous solution. The ammonia is added in the after-reaction period, i.e. in the period between ~he end of polymerization and ~ -d;rectly prior to cooling of the dispersion. It proved especially advan~
tageous to add the ammonia in the form of an aqueous solution soon after termination of the polymerization and at least half an hour or one hour prior to cooling of the dispersion. In special cases, the ammonia may also be added to the cooled dispersion, whereupon the dispersion is heated for half an hour or one hour at a temperature above 50C. If the copolymer contains free carboxyl groups in the latter case the dispersion should not be older than one day. The ammonia is preferably added at a temperature in the range of from S0 to 95C. It proved advantageous to choose the temperature of polymerization.

r- ~

- - ~,, . . - - -. .. . .
- . , ~ . , - ~ , l~S~577 If the ammonia is ~dded at high temperature, for example above 95C, considerable amounts of gas and foam may form.
Th~ can be avoided by operatlng under pressure and by adding defoaming agents~ if nece~sary~
Bg reacting tha halo~en ~ompound with ammonia at ele~ated tQmper~ture 20cordlnO to the in~en~on a comparable wet ad-hesion is obtained with a lower proportion of halogen compound in the copolymer as if the reaction were carried out at room temperature. The disperslons obtained in accordance with the invention can be used for making palnt~ having a high wet ad~
hes~on immediately after their preparatio~ whereas a reac-tlon with ammonia in the cold necessitates a prolonged inter-mediate storage which, of course, slows down the production.
For each equivalent of halogen in the copolymer two mol~
~Gmonla are ~dded. When the copolymer contains free carboxyl groups an additional amount of ammo~ia should be used for neutralization. Ammonia is added in such an amount that the hot dispersion has a pH above 8 and preferably above 9, mea- -sured with a gla~s electrode.
In the stead of ammonia, which is used as a gas or pre-~erably ~n aqueou~ ~olution, compounds splitting off ammonia at a temperature above 50C can be used, preferably hexamethy-lenetetramine~ In this case, at leas-t one mol of hexamethy-le~etetramine must be added ~or each mol of halogen.
Dispersions which are not stable at a pH of about 6.5, ad-Ju~table with hexamethylenetetramine, especially dispersions of acrylate homopolymer~, must be rendered more al~aline by addin~ ammonia.
29 The ~mount of halo~en oompound u~ed ~an vary ln tho rango `~ 5 ~

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...
- . ~ . .. . ,, - .. .

. . . . ; :
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XOE 74LF ~20 -1~5~577 of from 0.5 to 10% by weight, calculated on the total amount o~ monomers used~ WIth a con-tent of ~ess than 0.5% the wet adhe~ion strongly dim~nishes while the addition of more than 10~ by weight of hslogen compound doe~ not result in noticeable further improvement. In general, 1 ta 3~ by weight of glyci-dyl ester are sufficient. More t~a~ 10~ halogen compound can be used if the d~spersion shall be mixed with a dispersion free o~ halogen compound.I~ the manufacture of the dispersions according to the invention it proved advantageous to add the glycid~l ester to the polymeri~atio~ mixture when at least 40% and up to 80% of the other monomers have polymerized. In this manner plaxtics dispersions are obtained which have a high wet adhesion wlth a lower proportion of halogen compound as if the halogen compound were a~ed during the course of poly-merization constantly together with the other monomers. Inthis manner up to 60~ of halog~n compound can be SQVed.
The halogen compounds to be used in the manufacture of the dispersion~ according to the invention are ~-B-unsaturat-ed compound~ containing at least one nucleophilically substi-tutable halogen, for example chlorine or bromine, for examplechloro- or bromo-acetic acid vinyl ester, B-chloroethyl-vinyl ether, B-chloroethyl acrylate or methacrylate~ -The selectio~ o~ the other monomers is not critical. All monomers generally used for making plastics dispersions, which can be combined in accordance with the requirements of prac-tice, are suitable, for example vinyl esters of organic car-boxylic acids the ~cid moiety of which contains 1 to 30, pre-ferably 1 to 20 carbon atoms, for example vinyl acetate, vinyl 29 propionate, isono~anoic acid vinyl ester and vinyl ester of _ . . . ~ .
.. . . . . .. . .
.. ... .. , :. ;

.. . .

--- .. .. .. . .

. . .

HOE 74lF ~20 1~515~7 branched monocarboxylic aclds having up to 20 carbon atoms;
e~ters of acrylic acid or methacrylic acid having from 1 to 30 and preferably 1 to 20 carbon atoms in the alcohol moiety, for example ethyl acrylate, lsopropyl acrylate~ butyl acrylate, 2-ethylhexyl acrylate, methylmethacrylate, butylmethacrylate;
aromatic or aliphatic o~ unsaturated hydrocarbons such as ethylene, propylene, styrene, ~inyltoluene; vinyl halides sucn as ~inyl chloride; unsaturated nitriles such as acrylonitrile;
diesters of maleic acid or fumaric acid, for example dibutyl 1o maleate or dibutyl fumarate; cC-B-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, or crotonic acid and derivati~es thereof, ~or example acrylamide or methacrylamide.
When selecting the appropriate monomers or monomer com-binatlons the generally acknowledged conditions for the manu~acture o~ disper~ion paints have to be considered. In thç first place, care should be taken that polymers are form-ed which yield a co~erent film under the drying conditions of the coat o~ paint and the monomers for making copolymers should be selected so that, depend~ng on the respecti~e poly-merization parameters, the formation of copolymers with thehalogen compound~ can be expected. Some suitable monomers com-binat$ons are listed below:
vinyl acetate/butyl acrylate/chloro(bromo)-acetic acid vinyl ester, vinyl acetate/butyl acrylate/B-chloroethylvinyl ether, vingl acetate/butyl acrylate/B-chloroethyl-(meth)acrylate, vinyl acetate/dibutyl maleate/chloro(bromo)acetic acid vinyl estor, 29 vinyl acetate/dibutyl maleate/B-chloroethyl vinyl ether, , - . . . - - , -- . . ~: .
. .

F ~2~0 1~ 51 r37 7 vinyl acetate/dibutyl fumarate/chloro(bromo)acetic acid vinyl ester, - ~inyl acetate/isononanoic aoid vinyl ester/~hloro(bromo)acetic acid vi~yl ester, vinyl acetate/isononanoic acid ~inyl ester/B-chloroethylvinyl ether, vinyl acetate/isononanoic acid vin~l ester/B-chlor~ethyl(meth)-acryl~te 9 vinyl acetate/2-ethylhexannic acid vinyl ester/chloro(bromo)-acetic acid vinyl ester,vinyl acetate/2-ethylhexanoic acid vinyl ester/~-chloroethyl-vinyl ether, vinyl acetate/vinyl ester o~ branched carboxylic acid with 10 carbon atoms (10-C~acid)/chloro(bromo)acetic acid vinyl ester, vinyl acetate/10-C-acid vingl ester/~-chloroethylvinyl ether, vingl acetate/ethgle~e/chloro(bromo)acetic acid vinyl ester, ~ingl acetate/ethylene/~-chloroethyl ~inyl ethe~, vinyl acetate/ethylene/ vinyl chloride/chloro(bromo)acetic :~
acid vinyl ester, vinyl acetate/ethylene/vinyl chloricLe/B-chloroethylvinyl ether.
When the dispersions are intended for use in paints hav-ing a high wet adhesion they should contain as little as po~-~ible emulsifier. When, however, dispersions are to be pre-pared having a satisfactory stabil~ty a certain amount of emul- :
sifier must be added, especially if a small particle size is desired or if the polymeri~tion is carried out in the ab- .
sence o~ protectiYe colloids. Moreover, in man~ cases an emul~ifier is important to obtain a good wetting of the pig-29 me~ and a good dispersion thereof in the manufacture of the .

- ,.,., ~ ,.... ..

HOE_74/F ~20 ~ ~ 5~5~7~
paint. 0~ the other hand, an excessive content of emulsifier may detrimentally affect lmpor~an~ properties, for example the resistance ~o water. Consequentlyg the dispersions should contain at most 2% of ionic emulsifier an~ at most 4% of non-ionic emulsi~ier, calculated on the polymer content of thedlspersion.
Suitable non-ionic emulsifiers are, for example, alkyl polyglycol ethers such as the ethoxylation products of lAuryl, oleyl or stearyl alcohol or of mixtures such as coco-nut fatty alcohol; alkyl phenol polyglycol ethers such as theethoxylat$on products o~ octyl- or nonyl-phenol, diisopropyl-phenol, triisopropyl-phenol or di- or tri- tert.butyl-phenol;
or ethoxylation products of polypropylene oxide.
As ionic emulsi~iers anionic emulsif~ers are used in the Xirst place, for example alXali metal or ammonium salts o~
alkyl, aryl or alkylaryl sulfonates, sulfates, phosphates, phosphonates, or compounds h~ving different anionic end groups, oligo- or poly-ethylene oxide units possibly being contained betw~en the hydrocarbon radical and t~e anionic group. Typi-oal representati~es are sodium lauryl sulfate, sodium octyl~phenol glycol ether sulfate, sod~um dodecyl-benzene sulfonate, sodium lauryl diglycol sulfate, ammonium tri-tert.butyl-phenol penta- or octa-glycol sulfate.
A3 protective colloids there may be used natural substano-es 3uch as gum arabic, starch, alginates,or modified natural subs~ances such as a methyl, ethyl, hydroxyalkyl, or carboxy-methyl cellulose, or synthetic substa~ces, for example poly-vinyl alcohol,polyvinyl pyrrolidone, or mixtures of the afore-29 said substances. ~odl~ied cellulose deriYatives and synthetic ;,; ~ 9 ~ ~ :

~:-- ... :... . - - . ~ . . ... .
-. -. -.; ~ . .... ... . i.

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HOE 7~/F ~
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protective colloid~ are preferred.
To initiate and continue polymerization oil-soluble and/
or preferably water soluble radical forming agents or redox s~stems are used, for ex~mple hydrogen peroxide, potassium or ammonium peroxydisulfate, dibenzoyl peroxide~ lauryl peroxide, -tri-tert butyl peroxide9 blsazodiisobutyronitrile, either s~ngly or together with reducing components, for example sodium bisulf~te, Rongalite ~, glucose, ascorbic acid, and other com-pounds having a reducing action.
The following examples illustrate the invention, the parts being weigh-t unle~s otherwise stated.
E X A M P ~ E 1:
A polymerizstion mixture consisting of 650 part~ water 12 parts nonylphenol polyglycol ether having about 30 ethylene oxide units per molecule - 12 parts of a copolymer of 90 parts N-vlnyl-N-methyl-acetamide and 10 part~ maleic acid diiso-octyl e~ter 1.5 parts sodium acetate 0.9 part sodium vinylsulfonate 2.5 parts ammonium peroxidi~ulfate 48 parts vinyl acetate and 12 parts 10-C-acid vinyl ester was heated while stirring in a 2 liter three-necked ~].ask placed in a ~eating bath and equipped with stirrer, reflux condenser, dropping ~unnel and thermometer, whereby the poly-merization wa~ initiated. When the temperature had reached 2g 70C a mixture o~ 216 parts vinyl acetate and 54 parts 10-C-~- 10 -,~
.' ~ ' . . ' ': ' ~ . . ' .; : ' - ' '. ~ ~

OE ~4~ ~20 ~ ~ 51~7r7 acid vinyl ester wa~ metered in during the c~urse of approxi-mately 90 minutes. Directly thereafter, a mixture of 216 part~ vinyl acetate, 54 parts 10-C-acid vinyl ester and 18 part~ chloroacetic acid vinyl e~ter wa~ metered in during thé
cour~e of a ~urther 90 minute~, the total time of dosed addi- ~-tion being about 3 hours, the polymerization temperature was 70C.
After termination of the monomer addition a solution of 0.3 part ammonium peroxidisulfate in 15 parts ~ .
water was added, heat~n~ of the polymerizatinn mixture (70C) .. .
was conti~ued for 110 minutes, 23 part~ hexamethylene tetramine in 40 parts water were slowly added, the mixture w~s stirred for another 10 minutes at 70C and then cooled.
The di~persio~ obtained h~d a pH of 6.1 and a solids con-tent of about 50%. ~.
E X A M P L E 2: .
I~ an apparatus as described in Example 1 a polymerization ;~
mixture consisting of 618 parts water 18 parts nonylphenol polyglycol ether ha~ing about 30 ethylene oxide units in the molecule 1.5 parts sodium acetate 12 parts hydroxyethyl cellulose having~an average degree of polymerization of about 400 and a molecular weight o~ about 100 9 000 ~:
2.5 parts ammonium peroxidisulfate ~:;
48 parts vinyl ac~tate and 12 parts dibutyl a.leate ;:
29 were heated to 70C and at s id temperature there were added, ~`~
j;, - 11 ~, .

. HOE 74/F ~20 ~5~S77 during the course of 90 minutes a mixture of 216 parts vinyl acetate and 54 parts dibutyl maleate and direc~ly thereafter during the course of a further 90 minutes a mixture of 216 parts vinyl acetate, 54 parts dibutyl m~¦~Q~Q and 18 part~
bromoacetic acid vinyl ester. When the addition was termlnated 0.5 part ammoni.um peroxidisulfate in 15 parts water was added and the dispersion was heated for ~ further 2 hours.
One hour prior to cooling 40 parts am~onia of 25% strength were added whereby the pH was ad~usted to ~9.4. The dispersion had a solids content Gf about 50%~
E X A M P ~ E~
In a~ apparatus as described in Example 1 a polymerization mixture consisti~g of 625 parts water "
18 parts oleyl polyglycol ether ha~ing about 25 ethylene dioxide units ln the molecule 0.2 part sodium dodecylbenzene sulfonate 12 parts hydroxyethyl cellulose having an a~erage degree of polymerization of about 400 (mole-cular weight about 100~000) 1.5 part~ sodium acetate 2.5 parts ammonium peroxidisulfate and 63 parts of a monomer mixture composed of 540 ,oarts vinyl acetate 150 parts isononanoic acid virLyl ester ~nd 3b parts c~loroacetic acid vinyl e~ter was heated to 70C and the remaining monomer mixture (567 parts) w~s metered i~ over a period of 3 hours. When the addition 29 was terminated 0.5 part ammonium peroxidisulfate in 15 parts " ~- 12 -,:

.

. . .

~ ~ 5 ~r7 water were added and heatlng was continued for a further 2 hours. One hour prior to cooling t~e pH of the dispersion was ad~ust~d to 9~5 by adding 40 parts of ammonia of 25% strength.
The dispersion had a solids content of about 50%.
E X A M P L E S ~L-~Q1 Dispersions were prepared in the manner described in Ex-ample 3 with the exception that:
in Example 4 ammonia was added to the dispersion cooled to room temperature (about 25C) in Example 5 no ammonia was added to the dispersion in Example 6 no chloroacetic acid vinyl ester was incorporat-ed by polymerization, but ammonia was added at `
70C one hour prior to cooling -in Example 7 no chloroacetic acid vinyl ester was incorporat-ed and no ammonia added.
To prepare the dispersion paints aco~rding to the inven-tion ha~ing a high wet adhesion the dlspersions obtained ac-cor~ing to the preceding examples were blended with a pigment sus~)ension. Pigment suspensions or pigm~nt pastes of this type, which are suita~le for making dispersion paints of low pigment co~tent and especially gloss paints consist, for e~ample, of t~tanium dioxide uniformly dispersed in water. rhey contain, i~ generalg protective co.~loids such as cellulose derivatives for example hydroxyethyl cellulose~ and dispersing agents, for example salts of polytmet )acrylic acid or sodium polyphosph~te.
Usual constituents of pi~ ~ent suspensions are furthermore antimicrobic pre~erving a ents, antl-foaming agents, pH 3tabili-~ers and fillers. E~pec lly suitable titanium dioxide pig~
29 ments are the rutile and anatase modifications. For the manu-_ 13 -.: . . . -, ~ - - . .

: . i . , -. - . , : ~

. . ~ . . .. .. -facture of gloss p~ints the average particle diameter of the pig-ment should be nesr the lower limit of the light wave length, i.e. at about 0.4 to 0.2 micro~. For making dull paints of low pigment content special large surface silicate pigments could be concomittantly us~d. Dull paints of high binder ~o~ntcr.t yield paint coatin6s that are easily to clean.. The pigment paste may, of course, also contain colored pigments or -the desired shade is obtained by adding a shading dyestuff to the dispersion-paint containing the white pigment.
The pigment suspension can be prepared in kno~n manner, for example by dlspersing the pigment i~ a dissol~er, a ball mill or sand mill. For use in gloss paints the pigment sus-pension should ~ot contain noticaable amounts of pigment ag-gregates which would affect the gloss.
Auxiliaries such as plasticizers, cross linking agents, bu~fer substances, thickening agents~ thixotropic agents, rust pr~enting agents, alkyd resins, or drying oils may be added to the dispersion or the dispersion paint. Suitable plasti-ci~ers are not the solvents initially men~ioned as film con-solidation agents with temporary action but compounds which reduce the film forming temperature and remain in the polymer for a longer perlod of time, for example ~ibutyl phthalate.
The use of the plastic dispersio~s prepared according to the in~ention as binder in dispersion paints of low pigment content and dispersio~s containing the aforesa~d plastics dispersions also an ob~ect of the present invention.
To test the wet adhesion dispersion paints were prepared as ~oilows:
29 1~ Fir~t a pigment paste wa3 prepared by introducing in the - 14 - ~-'~

~ . . . . ~. . ...................................... .
. , - : . -- : ;-. - :

: ~0s~
indicated order into a vessel with stirrer 41.0 parts water 15.6 parts of a 3% aqueous solution of Tylose ~ H 20 o.4 part Calgon ~ N (solid)

3.0 parts dispersing agent PA 30 -1.0 part ammonia of 25% strength 2.0 parts of preserving agent 3.0 parts of anti-foaming agent and dispersing there-in 175 parts of titani~m dioxide having a particle size ~
of from 0.2 to 0.4 micron with the use of ;
a dissolver and adding 10.0 parts propylene glycol.
This pigment paste was prepared in a large amount so that ~ -for the blends with the dispersions to be tested equal condi-tions, for example as regards the pigment dispersion, were ensured. ;;
The pigment paste 1) was mixed with 2. 710 parts of the respective dispersion (with a solids contents of 50%~ which had been admixed with 2.0 parts ammonia of 25% strength if the pH
did not exceed approximately 7.
To the pigment paint obtained a mixture 3. of lO parts butyl diglycol acetate and 27~0 parts 1~2-propylene glycol was then slowly added ~hile stirring. ~`
For the manufacture of the individual paints a correspond-ing proportion of the pigment paste was mixed, while slowly stirring with the dispersion approximately one day old where-_15 - ;~

- .

HOE 7~1F 320 ~ 5~7~
upon the solvent3 men-tioned sub 3) were added. After complete confection7 the paint~ were passed through a sieve.
The palnts were allowed to stand for one day and then spread on gla~s plates and steel sheets onto which a pigment-ed glossy air drying alkyd resin enamel had been sprayed and whlch had been kept after drying for 24 hours a-t 100C. A
film appllcator was used having a slit diameter of 200 mic-ro~sO After a drying period o~ 24 hours the wet adhesion of the gloss paints was tested according to the two following methods:
1) Abrasion test The glass plates with the dried coating of dispersion paint were inserted in a mechanical abrasion device as des-cribed, ~or example, in German Offenlegungsschrift 2,?62,956 and sim~lar to the Gardner Washability and Abrasion Machine, but having a moving length of approximately 1.20 m in a man-ner such that the applied ~ilms of dispersion paint were i~
a rrertical position with respect to the movi~g direction of the brush. Due to the long moving distance about 15 paints co~lld be simultaneously tested in one run. A brush with hogts bristle~ was used which, at the beginning of the test, had been wetted with distilled water. During the test the ~rea on which the brush moved was also wetted with distilled water ~o that the brushed areas were permanently covered with a water film. With a poor wet adhesion the dispersion paint was brushed o~f the substrate after a few movements of the brush and torn at the bound~ry between wetted and dry film.
The wet adhesion is the bett r the higher the number o~ move~
29 ments of the bru~h until the film is shifted aside. The dis-., . . ~. . ; .
... . .

~.............. - ; - .

~ ~ 5~ 7 persion paint has ~ optimum wet adhesion when in the wet-ted area the film is not damaged after 3,000 passages of the brush, one passage including a backward and forward stroke.
2) Condensation test A rectangular thermostat was used one half of which was filled with water of 50C and in the gas space of which above the water level a fan was mounted. Th~ upper opening was cov-ered with the steel sheets with the coa~ed surface in down-ward position 50 that the thermostat wa closed. The thermo-stat was kept ~n a room ma~ntai~ed at 23C. Owing to the tem-perature difference steam condensed on the lower surface of the sheets and acted on the coats of paint. After 15 minutes of action the sheets were remo~ed and the coatings evaluated.
With an ~satisfactory wet adhesion blisters form between the film of dlspersion paint and the alkyd resin lacquer and the film can be easily shifted aside. A film ha~ing a good wet adhesion is still free of blisters after a period of 4 hours and cannot be shifted.
The test results are listed in the following Table.
Example abrasion t~st, number st~bility in con-No. of double ~troke~ of densation test ,`-1 ~ ~000 ~ 4 hours 2 ~ 3000 ~ 4 hours 3 > 3000 > 4 hours

4 2000 2 hours 400 25 minutes 6 350 2 hours ~0 7 400 70 minute~ ~ ;
- 17 - ~
,. . . ~ . . .

- : ~

Claims (3)

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

1. A process for the manufacture of a plastics dispersion suitable for making dispersion paints having a high wet adhesion, which comprises treating, at a temperature above 50°C, a plastics dispersion obtained by copolymerizing in an aqueous medium olefinically unsaturated monomers with 0.5 to 10% by weight, calculated on the total amount of monomers, of nucleophilically substitutable .alpha.-.beta.-unsaturated halogen compounds with two equivalents of ammonia for each equivalent of halogen compound and, in addition, an amount sufficient to give the hot dispersion a pH above 8, or reacting the plastics dispersion at a temperature above 50°C with one mol hexamethylene tetramine for each mol halogen compound, and where required rendering the dispersion alkaline by the addition of ammonia.

2. The process of claim 1, wherein the halogen compound is added to the polymerization mixture after at least 40% and at most 80% of the other monomers have been polymerized.

3. A dispersion paint of low pigment volume concentration and high content of organic solvents containing as binder a plastics dispersion obtained by copolymerizing in an aqueous medium olefinically unsaturated monomers together with 0.5 to 10% by weight, calculated on the total amount of monomers, of nucleophilically substitutable .alpha.-.beta.-unsaturated halogen com-pounds and reacting the halogen compound with ammonia at a temperature above 50°C.