Note: Descriptions are shown in the official language in which they were submitted.
HOE 74/F 320
~ 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-
- 2 ~
: .... - - ~ . ~ .
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~
51577
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- ~
- 4 -
- - ~,, . . - - -
. .. . .
- . , ~ . ,
- ~ ,
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 ~
., _ . _ _
: ~ ., ., ,.. - ` - - - .. : .- :
...
- . ~ . .. . ,, - .. .
. . . . ; :
- . .- .
. . . . ... .
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
- 6 -
_ . . . ~ .
.. . . . . .. . .
.. ... .. , :. ;
.. . .
--
- .. .. .. . .
. . .
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
- 8 -
.
- ,.,., ~ ,.... ..
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.
.. . .
HOE 7~/F ~
.._.
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 -
,:
.
. . .
HOE 74/F 320
~ ~ 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-
- 16 -
.,
. . ~. . ; .
... . .
~.............. - ; - .
~ ~ 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 - ~
,. . . ~ . . .
- : ~
