Note: Descriptions are shown in the official language in which they were submitted.
d2~
Aqueous coating agents, for example for lacquerin~ furniture, have
hitherto generally contained synthetic resins, such as acrylic polymers or
cellulose esters, as the film-formang agents. Methods Eor preparing aqueous
emulsions of suitable cellulose derivatives are known and are described,
for example, in German Auslegeschrift 1,286,672 and United States Patent
3,615,792. Emulsions of cellulose esters, for example of nitrocellulose,
cannot be used as the sole binders for coating agents, because they only
produce brittle and fragile films. m ey must be combined with ketone resins
or vinyl acetate copolymers in order to achieve glossy coatings with good
mechanical properties.
Cellulose esters, for example nitrocellulose, usually combined
with alkyd resins, are used for lacquering wcod or similar materials. m is
combination leads to coatings of high gloss, adequate hardness, good
elasticity and excellent flow, but it is not possible to work with aqueous
emulsions; instead, these combinations have hitherto had to be processed
from organic solutions. All attempts hitherto to emulsify aIkyd resins and
cellulose esters lead either to emulsions of inadequate stability or to
e~,ulsions with particles which are too coarse and which do not permit
levelling to give glossv coatings.
m e invention relates to aqueous dispersions of coating agents
in which the dispersed particles have a size from 0.1 to 1.5~ camprising
5-50 parts by weight of cellulose ester, 5-30 parts by weight of plasticiser,
5-50 parts by weight of alkyd resin, 30-135 parts by weight of water and
0.5- 10 parts by weight of emulsifier, in which ~he emulsifier is a vinyl
alcohol homopolymer or copolymer and the alkyd resin is a short-oil aIkyd
resin containing 5-50% by weight of oil.
These dispersions are stable and can give coatings of
--2--
. . .
substantially ~aultlass glos~.
The invention further relates to a process for the pre-
paration of such dispersions o~ coating agents, which is
characterised in that a cellulose ester, an alkyd resin and a
plasticiser are dissolved in an organic solvent, this solution
is dispersed into a solution consisting o~ emulsi~ier and water
and the organic solvent is removed by distillation.
The size of the dispersed particles is particularly
important for the stability of the di~persion and also ~or its
behaviour in film formation. According to the
invention it is preferably 0.1 to 0.5~ and it does not change
substantially even on prolonged storage at 5-50C.
Cellulose esters which can be used in accordancs with
the in~ention are, in particular, cellulose acetate, cellulose
aoetobutyrate, cellulose acetate-benzoate and cellulose sorbate-
acetate and mixtures of these esterq. Ni~rocellulose, for
example the customary collodion cotton qualities, that is to
3ay cellulose nitric acid esters having a nitrogen content of
; 10.2 to 12.4% by weight, is more particularly suitable.
Plasticisers within the me~ing of the invention are,
i~ particular, esters, such as dibutyl phthalate, dioctyl
phthalate, dicyclohexyl phthalate, dibutyl adipate, benzylbutyl
adipate, dioctyl adipate, phosphoric acid esters, such as tri-
cresyl phosphate, triphenyl phosphate or trioctyl phosphate,
~nd also benzenesulphonic aci~ N-methylamide.
Suitable alkyd resins are preferably oil-modified or
; ~atty acid-modified alkyd resins. Alkyd resins are under-
stood a~ polyesters which are prepared from alcohol~ and
carboxylic acids by polycondensation according to known pro-
30l cesses and such as are defined; for ex~mple, in Ullmanns-
Enzyklopadle der Teohnischen Chemie (Ullmann's Encyclopaedla
- 3 -
9~L
of Industrial Chemistry) or are described in D.R. Sol~mon, The
Chemistry of Organic Filmformers, page 75-111. In general, the
alcohols employed cantain 1 to 15, preferably 2 to 6, C atcms and
the acids used, or their ester-formang derivatives, contain 2 to 14,
preferably 4 to 12, C atoms. These alkyd resins can optionally be
mixed with other polyesters, for example also with oil-free poly-
esters.
Examples of suitable alcohols are pentaerythritol,
glycerol, trimethylolpropane, trimethylolethane, 1,2,4-butanetriol,
1,2,6-hexanetriol, ethylene glycol, propane-1,2-diol,propane-1,3-
diol, butane-1,2-diol, butane-1,3-diol and butane-1,4-diol, neo-
pentylglycol, diethylene glycol, triethylene glycol, dipropylene
glycol, hexane-1,6-diol,1,2-bis-(hydroxymethyl)-cyclohexane and 1,4-
bis-(hydroxymethyl)-cyclohexane, 2-ethylpropane-1,3-diol, 2-ethyl-
hexane-1,3-diol, cyclohexane-1,2-diol, cyclohexane-1,4-diol and
adipic acid bis-ethylene glycol ester; benzyl alcohol, cyclohexanol
and other monoalcohols having 1 to 6 C atoms. Preferred alcohols
are gly oerol, trimethylolpropane, neopentylglycol and pentaerythri-
tol.
The following carboxylic acids, or their ester-formLng
derivatives, may be mentioned as examples of suitable ad d COmpOIl-
ents: phthalic acid, isophthalic acid, terephthalic acid, tetra-
hydrophthalic acid and hexcahydrophthalic acid, endomethylene-
tetrahydrophthalic acid, succinic acid, adipic acid, sebacic acid,
trimellitic acid, benzoic acid and their derivatives, such as, for
example, p-tert.-butylbenzoic acid and hexahydrobenzoic acid.
Phthalic acid is the most customary.
In the alkyd resins which are employed for the coating
emulsions according to the invention, the proportion of oil can be
5 to 50% by weight, calculated as triglyceride and relative
11~105al
to the alkyd resin. The drying or non-drying fatty aciJs
which generally contain 6 to 24 C atoms, can be employed either
as such or in the form o~ their glycerol esters (triglycerides),
Animal and vegetable oils, ~ats or fQtty acids~ such as, ~or
example, coconut oil, groundnut oil, castor oil, olive oil,
soya bean oil, linseed oil, cottonseed oil 9 sa~flower oil or
safflower oil ~atty acids, dehydrated castor oil or castor oil
fatty acid, mono-unsaturated ~atty acids, lard, tallow and
train oils, tall oil fatty acid and synthetic fatty acids, ~ay
be mentioned as being suitable.
Suitable emulsiflers are homopolymers and copolymers of
vinyl alcohol, for example polyvinyl alcohols which are formed
by hydrolysis of polyvinyl acetate and which are available
commercially, for example under the de~ignation Polyviol
15 I W 25/240 and W 25/140. Hydrolysed copolymers of vinyl-
pyrrolidone and vinyl acetate are also suitable.
The dispersions o~ coating agents of the invention pre-
ferably contain alkyd resins having an oil content of 20 to
45%.
The coatings according to the in~ention can be produced
by dissolving the alkyd resin, the cellulose ester and the
plasticiser in a polar solvent which is not soluble in water9
and which can be removed by dis~illation from the emulsion to
be ~ormed, combining the solution with an aqueous solution of
the emulsifier and thus forming an oil-in-water emulsion by
means of high shearing forces. The organic solvent is then
removed by di~tillation, on ~ts own or in the form o~ an aqueous
a~eotrope. Solvents ~hich are particularly suitable are
alkyl acetates and alkyl propionates. The aqueous emulsion
which remains can be diluted with more water or a suitable
coalascing agent can be added to it. In the ~ollowing
- 5 -
-~ Trac~
this will be designated a secondary emulsion.
One or more coalescing or aggregating agents can also
be added to the dispersion in order to achieve a clear film of
high gloss. Coalescing agents which form an azeotrope
with the water are preferred here. It is then necessary to
add to the dispersion sufficient coalescing agent so that -the
azeotrope is first distilled o~ and, in addition, to add
further ooalescing agent which ef~ects the aggregation of the
particles. Possible coalescing agents are ethylene
glycol monomethyl ether, ethylene glycol monoethyl ether and
ethylene ~lycol monobutyl ether-acetate diethylene glycol,
diethylene glycol monobutyl ether, diacetone alodhcl methylgly-
col acetate, methyl amyl ketone and diisobutyl ketone.
The primary emulsion consisting of cellulose ester,
alkyd resin, emul~ifier, plasticiser, water and organic ~olvent
i~ produced in a commercially available device having an
adcquately high peripheral speed of 5 to 50 m/second, prefer
ably 10-30 m/~econd.
Examples are: Ultra-Tu~a ~type 45 of 10,000 revolutions
per minute; Gaulin homogeniser, di~;sol~er and beadmillsO
The emul~i~ica~ion time in the Ultra-Tun~x~hould not
; be more than 2 minutes, since otherwlse too great an
e~olution of heat takes place This time is adequate to
produce small, spherical particle~ of Q1-1.5pr0~rably Q1-0.5/u Pro~th~
~ ltu~rts o~ the ultimate emulsion.
In a pre~erred embodime~, the aqueou~ coating composit~on~
contain add1tionally 4 - 40 par~s by w~ight o~ an urea and/or
m~lamine re~inO
Ur~a a~d melami~e re~ln~ in thi~ context are art recognized
conden5ation product~ o~ ur~a or melamine and ~ormaldehyde which
ar~ made in an alkaline medium. They are 501uble in water and are
add~d to the di~p~rsion~ in the Iorm OI aqueou~ ~olutions~ Their
6 -
ef~ect is a cros~linking of the coatings obtained from the disper
~ions which improves their stabillty and gloss. Catalytic amounts
of p-toluene sulfonic acid accelerate crosslinking.
A solution in ethyl acetate wa~ prepared from:
100 g of nitrocellulose chips containing approximately 12% of
nitrogen, Standard Specification 24 E in accordance with
DIN 53,179, consisting of 82% of collodion cotton and 18%
of dibu-tyl phthalate,
0 100 g of groundnut oil fatty acld alkyd resin having an oil
content of 41~, and
of ethyl acetate
500 g
After stirring slowly for approximately 3 hours a
clear solution was obtained which WR3 combined with 300 g o~
a 3% strength aqueous solution of polyvinyl alcohol (Polyviol
W 25/140), whilst stirring slowly, The mixture was then
dispersed for 2 mi~utes in an Ultra-Tur~ax~ -type 45 laboratory
~ disperser by raising the speed of rotation continuously to
10,000 revolutio~s per minute. The solvent is distilled
o~f under reduced pressure. A primary emulsion having a
~olids content of 40% and a ~low viscosity oX 34 second~ in the
DINcup No.4 is thus obtained, which was processed in Example
and 30
~ son example:
A dispersion was prepared as described in Example 1,
exceptthat instead of the polyvin~l alcohol 300 g of ~n
aqueous solution of a non-ionic fatty acid ester (emulsifier
Emulpho~Y~EL of BASF) were used. This ga~e an emulsion
30 which wa~ stable for a short time and which ga~re an average
size of 13~ in a determination of particle pattern.
7 -
A dispersion was prepared from:
100 g of groundnut oil fatty acid alkyd resin having an oil
content of 41%)
100 g of nitrocellulose chips as in Example 1, and
o~ ethyl acetate
500 g
After stirring for 3 hours, a clear solution was
obtained ~hich is combined with 500 g o~ a 2.5% strength solu-
tionofpolyvlnylalcaohol (Polyviol W 25/140) in water. The
procedure described under Dispersion 1 was then followed. A
primary emulsion with a solids content of approximately 29%
and a flow viscosity of 28 secondsin theDIN cup NoO 4is obtained
.U3~
I Example 1 (Comparison)
A lacquer of the following composition was prepared:
Groundnut oil fatty acid alkyd resin with
41% of oil, 60% strength solution in xylene 152 parts by weight
~I Collodion cotton (cellulose nitric ac:id ester
1 ~ontaining approximately 12% of nit;rogen),
Standard Specification type 24 E, DIN
; 53,179, in the form of chips111 parts by weigh~
Dibutyl phthalate 8 parts by welght
i Ethylene glycol monoethyl ether59 parts by weight
2S Bu~yl acetate 190 parts by weight
Ethyl acetate 140 parts by weight
Xylene 300 parts by weight
Ethylglycol acetate40 parts by weight
~ The resulting lacquer exhibited a viscosity correspond-
ing to a flow time of approximately 30 seconds, measured in
accordance with DIN 53,211 (DIN cup No.4). The curing to
give films and the assessment are described in Table 1.
- 8 - .
Example 2
A dispersion of the following composition was prepared:
Dispersion from Example 1, 40% strength
in water 550 parts by weight
5 ~ibutyl phthalate 10 parts by weight
Ethylene glycol monomethyl ether124 parts by weight
Ethylglycol acetate 44 parts by weight
4-Methyl-4-hydroxypentan-2-one32 parts by weight
Water 234 parts by weight
Levelling agent (alkylbenzenesulphonate) 6 parts by weight
The resulting dispersion exhibited a viscosity corres-
ponding to a flow time of approximately 15 seconds, measured
in accordance with DIN 53,211,
g _
.
h
q~ ~
U~ 0
U~ U~ ~
a~ ~ ~o o
P u~
El ~ ~ ~4 ~1 ~ QO h
X o 0 o r-l o ~
h ~C
a~
~ ~ 'Q
tn~ ~ o
~0 ~o o ~ ~ g~
o ~ Q ~ 0 r~
o a~ ~> ~ ~ 0 t~ ~ rl h
~3 o a~ o o 0 h ~ o
~C O O ~1 ~1 0 Il~ ~ V $~ ~
~ ~ ~ æ ~ :~ o
~Q
~0
~H ~
a~ o o
a~ o
.. æ
~1 a) ~ o o o a~ h
~1 ~ ~
~ ~1 X 0-~1 ~
bD td ~ ~q h
~n ~ o ~ ~
u~ h ~ ~q
~0 oO ~
h ~J h
$ ~ o~
h ~, r~ w h ,~
,s ~ h ~0 ~ o
Q~ ~q 0 ~I h w ~ d w ~d
~ O o
rl w 0 ~ O
+~ 1 ~ O O
:~ d a) ,1~ ,~ ~ ~ o
~ ~ ~ ; o
~ n o u~ ~ ~q o o
!~ ~ o~ al O ~ h t-l C) V
h ~ O O ~1 a) ~
Le A 17 8~6 - 10 -
