LIGHT-STABILISED BINDERS FOR COATING COMPOSITIONS

LIANTS PHOTOSTABILISES POUR COMPOSITIONS DE REVETEMENT

English Abstract

The stabilised binder is a mixture of two copolymers and at least one curing
agent. The
one copolymer contains fluorine or silicon and a UV absorber in copolymerised
form. The
other copolymer is an acrylic resin. Suitable curing agents are melamine
resins or
polyisocyanates.

Claims

-19-
CLAIMS:
1. ~A curable composition comprising (a) a fluorine-
or silicon-containing copolymer, (b) a (meth)acrylic
copolymer, and (c) at least one curing agent, each of which
two said copolymers contains functional groups which are
able to react with the curing agent, wherein component (a)
contains a UV absorber in copolymerised form.
2. The composition according to claim 1, wherein the
copolymers (a) and (b) contain hydroxyl groups and the
curing agent is a compound which is able to react with
hydroxyl groups.
3. The composition according to claim 1 or 2, wherein
component (a) is a fluorine-containing copolymer.
4. The composition according to claim 1, wherein
component (a) is a copolymer comprising:
(a1) an olefin containing more than one fluorine atom,
(a2) at least one of an alkylvinyl ether and a
cycloalkylvinyl ether,
(a3) a hydroxyalkylvinyl ether, and
(a4) an ethylenically unsaturated derivative of a UV
absorber selected from the class of the 2-(2-hydroxyphenyl)-
benzotriazoles, of the o-hydroxyphenyl-s-triazines, of the
o-hydroxybenzophenones or of the oxalanilides.
5. The composition according to claim 4, wherein
component (a) additionally comprises:
(a5) further copolymerisable compounds selected from
styrene, .alpha.-methylstyrene, acrylic acid, methacrylic acid,

-20-~
and the alkyl esters thereof, mono- or dialkyl maleates, and
mono- or dialkyl maleimides.
6. ~The composition according to claim 4 or 5, wherein
component (a1) is chlorotrifluoroethylene and is present in
the copolymer (a) in an amount of at least 30% by weight.
7. ~The composition according to any one of claims 4
to 6, wherein component (a4) is a derivative of 2-(2-
hydroxyphenyl)-benzotriazole or of o-hydroxyphenyl-s-
triazine.
8. ~The composition according to claim 1, wherein
component (a) is a silicon-containing copolymer.
9. ~The composition according to claim 1, wherein
component (a) is a copolymer of
(a1) an ethylenically unsaturated organosilicon compound,
(a2) at least one alkyl acrylate or alkyl methacrylate,
(a3) a hydroxyalkyl (meth)acrylate, and
(a4) an ethylenically unsaturated derivative of a UV-
absorber selected from the class of the 2-(2-hydroxyphenyl)-
benzotriazoles, of the o-hydroxyphenyl-s-triazines, of the
o-hydroxybenzophenones or of the oxalanilides.
10. ~The composition according to claim 9, wherein
component (a) additionally comprises:
(a5) further copolymerisable compounds, selected from
styrene, .alpha.-methylstyrene, acrylic acid, methacrylic acid,
and the alkyl esters thereof, mono- or dialkyl maleates, and
mono- or dialkyl maleimides.

-21-
11. ~The composition according to claim 9 or 10,
wherein component (a1) is a compound of formula
<IMGS>
wherein n is 0-3, m is 0-3, R is H or CH3, Y is C1-C8alkyl
and Z is C1-C8alkoxy or -OCH2CH2OCH3.
12. The composition according to any one of claims 9
to 11, wherein component (a4) is a derivative of 2-(2-
hydroxyphenyl)-benzotriazole or of o-hydroxyphenyl-s-
triazine.
13. The composition according to any one of claims 1
to 12, wherein component (b) is a copolymer of several alkyl
acrylates or alkyl methacrylates, a hydroxyalkyl
(meth)acrylate and acrylic or methacrylic acid.
14. The composition according to any one of claims 1
to 13, wherein component (c) is at least one of a melamine
resin and a polyisocyanate.
15. The composition according to any one of claims 1
to 14, wherein the weight ratio of (a) to (b) is 20:80 to
80:20, and the weight ratio of (c) to the sum of (a) and (b)
is 3-80 to 100.

-22-
16. ~The composition according to claim 1, wherein the
copolymer (a) contains a copolymerisable sterically hindered
amine.
17. ~Use of the composition according to any one of
claims 1 to 16, as binder for clear or pigmented coating
compositions.
18. ~A clear or pigmented coating composition which
contains as binder the composition according to any one of
claims 1 to 16.
19. ~The clear or pigmented coating composition
according to claim 18, which contains a light stabiliser
selected from the class of the sterically hindered amines.
20. The clear or pigmented coating composition
according to claim 19, which contains a derivative of
2,2,6,6-tetramethylpiperidine.
21. A cured film obtained by curing a coating
composition which contains as binder the composition
according to any one of claims 1 to 16.

Description

~~n~;~,n ,y,
~~~:~~t3~sJ
-1-
A-17955 +
Light-stabilised binders for coating compositions
The present invention relates to a mixture of two copolymers and at least one
curing agent.
The one copolymer contains fluorine or silicon and a UV absorber in
copolymerised form.
The other copolymer is an acrylic resin. The mixture can be used as binder for
weather-resistant coating compositions.
Coating compositions for outdoor applications often contain acrylic resins as
binders
because they are relatively weather-resistant. Such binders are normally
copolymers of
different acrylic or methacrylic acid derivatives. Light stabilisers such as
UV absorbers or
sterically hindered amines or both can be added to enhance weatherability
(q.v.
US-A-4 314 933).
Recently, fluorine-containing binders for coating compasitions have been
disclosed, for
example copolymers of chlorotrifluoroethylene with vinyl ethers. These
developments are
described, for example, in Progress in Orgarizc Coatings 16 (1988), 113-134, (
q.v. also
US-A-4 576 977). Coating compositions based on such fluorinated resins not
only have
excellent weatherability, but also high gloss and dirt resistance. Their
drawback is the high
cost of organofluorine materials. The same applies to silicon-containing
binders such as
silicon resins.
It has therefore already been proposed to blend such fluorine- or silicon-
containing
copolymers with acrylic resins, which acrylic resins have a greater solubility
in solvents
than the fluorine- or silicon-containing copolymers (q.v. (GB-A-2 192 399).
It has now been found that the weatherability of such binder systems can be
further
appreciably enhanced by incorporating in the fluorine- or silicon-containing
copolymer a
UV absorber by copolymerisation.
Accordingly, the present invention relates to a composition comprising (a) a
fluorine- or
silicon-containing copolymer; (b) a (meth)acrylic copolymer, and (c) at least
one curing
agent, each of which two said copolymers contains functional groups which are
able to

r~,~~,
~~~'~ ~< ~~
-2-
react with the curing agent, wherein component (a) contains a UV absorber in
copolymerised form.
Suitable functional groups are typically hydroxyl, carboxyl, anhydride or
epoxy groups.
Preferably both copolymers contain hydroxyl groups as functional groups and
the curing
agent is a compound which is able to react with hydroxyl groups.
Preferred compositions are those in which the solubility parameter determined
by the
formula of K.W. Suh and J.M. Corbett (J. Appl. Pol. Sci. 12 (1968), 2359) of
component
(b) as well as of component (c) is greater than that of component (a) by at
least 0.5.
Copolymer (a) contains either an organofluorine component or an organosilicon
component in copolymerised form.
When it contains an organofluorine component, copolymer (a) preferably
comprises
(at) a polyfluoroolefin,
(a2) at least one alkyl- and/or cycloalkylvinyl ether,
(a3) a hydroxyalkylvinyl ether,
(a4) an ethylenically unsaturated derivative of a UV absorber selected from
the class of
the 2-(2-hydroxyphenyl)benzotriazoles, of the o-hydroxyphenyl-s-triazines, of
the
o-hydroxybenzophenones or of the oxalanilides, and
(as) further optional copolymerisable compounds.
Exemplary of polyfluoroolefins are l,l-difluoroethylene, tetrafluoroethylene
or
hexafluoropropylt,ne, but preferably chlorotrifluoxoethylene. Preferably the
copolymer (a)
contains at least 30 % of chlorotrifluoroethylene. ,
Alkylvinyl ethers are typically methylvinyl ether, ethylvinyl ether,
propylvinyl ether,
isopropylvinyl ether, butylvinyl ether, hexylvinyl ether or octylvinyl ether.
An illustrative example of cycloalkylvinyl ether is cyclohexylvinyl ether.
Illustrative examples of hydroxyalkylvinyl ethers are 2-hydxoxypropylvinyl
ether,
3-hydroxybutylvinyl ether or 4-hydroxypentylvinyl ether.
Illustrative examples of copolymerisable derivatives of

-3-
2-(2-hydroxyphenyl)benzotriazoles are the compounds of the following formulae:
HO R2
R3 r /N\
N
N~. R1
(CH2) X CO-X-A-O-CO-~=CH2
HO Rz
R~ / % \
N
\N~ ~ 1
(CH2~-O-CO-C=CHZ
HO R2
R3 ~ /N\
N
\N~ i H3 ~ 1
C - (CH2~-CO-X-A-O-CO-C=CH2
CH3
CH3
;1
HO I ~ (CH2)g-CO-X-A-O-CO-C=CH2
R3 / / \ ~ CH3
N/
R2

RI
HO CH2NHCOC=CH2
R3
N
\ . wN/.
R2
OT
HO
OH R1
R3
OCH2CHCH2-O-CO- ~ =CHi
~N~
wherein x is 0-3, Rl is H or CH3, R2 is H, Cl, Cl-C$alkyl, C3-C$alkenyl or C3-
C~aralkyl,
R3 is H, Cl, Cl-C4alkyl or Cl-C4alkaxy, X is -O- or -NH- and t~ is C2-
CBalkylene,
2-hydroxytrimethylene or cyclohexylene.
Examples thereof are the compounds of the following formulae:
HO t-C4Hg
~N~
\ ~.N/
CH2CH2COOCH2CH20COCH=CH2
HO t-C4H9
i \N ~ ~
CH3
\ N/ I
CH2CH2COOCH2CH(OH~H20COC=CH2

-5-
HO t-C4H9
/ .i \
N
o \N/
CH2CH2C0 O OCOCH=CH2
HO
OH CHg
/ ~N\
/N OCH2CHCH20COC=CH2
~N~
HO t-C4H9
/ iN\N
°N/
CH2CH2C0----O OCOC(CH3~CH2
HO t-C~H9
/ i\
w wN/
CHZCH2COOCHZCH(CHg)OCOCH=CH2
HO t-C4H9
~N~
\N/
CH2CH2-CONHCH~CH20COCH=CH2

-6-
HO ~_C4H9
~N /
~N'~
~CH2CH2COOCH2CH(OH~H20COCH=CH2
Illustxative examples of copolymerisable derivatives of o-hydroxyphenyl-s-
triazines are
the compounds of formula
I I
O ~B-O P CO-C=CH2 O CHa(CH2)COO- B-OCO- C=CH2
P
H Or ~ OH
N ~N N \N
Ar N EST Ar N
wherein p is 0 or l, RI is H or CH3, Ar is phenyl or phenyl which is
substituted by
Ct-C4alkyl and/or Cl, and B is C~-CBalkylene, cyclohexyl~ne or -CH2CH(OH)CH2-.
Exemplary of such compounds are:
2,4-diphenyl-6-(2-hydroxy-4-acryloyloxyethoxyphenyl)-s-triazine,
2,4-bis(2,4-dimethylphenyl)-5-(2-hydxoxy-4-acryloyloxyethoxyphenyl)-s-
triazine,
2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-4-[2-hydroxy-3-methacryloyloxy-
propoxy)phenyl)-s-triazine,
2,4-bis(2,4-dirnethylphenyl)-6-(2-hydroxy-4-methacryloyloxyphenyl)-s-triazine.
Exemplary of copolymerisable o-hydroxybenzophenones are the compounds of
formula

~~~~'r~fl
HO R
1
R ~ O
' ~ C O -- f B-O p CO-C=CH2
R5
wherein p is 0 or 1, B is C2-C$alkylene, cyclohexylene or -CH2CH(OH)CH2-, Rl
is H or
CH3, and R4 and R5 are each independently of the other H, Cl-C4alkyl, ~OI-I or
C1-C~alkoxy.
Exemplary of such compounds are:
2-hydroxy-4-acryloyloxybenzophenone,
2-hydroxy-4-methacryloyloxybenzophenone, '
2-hydroxy-4-(2-acryloyloxypropoxy)benzophenone,
2-hydroxy-4-(2-hydroxy-3-acryloyloxypropoxy)benzophenone,
2,2'-dihydroxy-4-(2-methacryloyloxyethoxy)benzophenone,
2-hydroxY-4-(2-acryloyloxyethoxy)benzophenone.
Illustrative examples of copolymerisable oxalamides are compounds of formula
R7 ~ HN-CO-CO-NH ~ R6 Rt
Rg
O--°°f B-O p CO- C= CH2 ..
wherein p is 0 or 1, B is CZ-C$alkylene or -CH2CH(OH)CH2-, Rl is H or CH3, and
Rs, R~
and R8 are each independently of one another H, Cl-Ct2alkyl or Ct-Ct2alkoxy.
Examplary of such compounds are:
N-phenyl-N'-(2-acryloyloxyphenyl)oxalarnide,
N-p-tolyl-N'-(2-acryloyloxyphenyl)oxalamide,
N-p-methoxyphenyl-N'-(2-acryloyloxyphenyl)oxalamide,
N-p-methoxyphenyl-N'-[4-(2-acryloyloxyethoxy)phenyl]oxalarnide,
N-p-methoxyphenyl-N'-[2-(2-methacryloyloxypropaxy)phenyl]oxalamide,
N-phenyl-N'-[4-(2-hydroxy-3-acryloyloxypropoxy)phenyl]oxalarnide,
N-p-methoxy-N'-[2-(2-hydroxy-3-methacryloyloxypropoxy)phenyl]oxalamide,

_g_
N-o-ethylphenyl-N'-[2-(2-acryloyloxyethoxy)phenyl]oxalamide.
Preferably componente (a4) is a derivative of 2-(2-hydroxyphenyl)benzotriazole
or of
o-hydroxyphenyl-s-triazine.
Exemplary of further copolymerisable compounds (component as) are styrene,
«-methylstyrene, acrylic and methacrylic acid and the alkyl esters thereof,
acrylonitrile,
mono- or dialkyl maleates or maleimides. The copolymer may also contain as
further
copolymerisable compound (as) a copolymerisable sterically hindered amine.
Illustrative
examples of suitable sterically hindered amines are 2,2,6,6-
tetramethylpiperidine-4-
(meth)acrylate or and 1,2,2,6,6-pentamethylpiperidine-4-(meth)acrylate.
Component (al) is preferably chlorotrifluoroethylene and is preferably present
in
copolymer (a) in an amount of at least 30 % by weight.
Preferably the fluorine-containing copolymer comprises 30-60 % by weight of
component
(al), 20-50 % of component (a2), 5-20 % of component (a3), 0.5-10 % of
component (a~)
and 0-15 % of component (as).
If the copolymer (a) contains a silicon-containing component, then (a) is
preferably a
copolymer of
(al) an ethylenically unsaturated organosilicon compound,
(a2) at least one alkyl acrylate or alkyl methacrylate,
(a3) a hydroxyalkyl (meth)acrylate,
(a4) an ethylenically unsaturated derivative of a iJV absorber selected from
the class of
the 2-(2-hydroxyphenyl)benzotriazoles, of the o-hydroxyphenyl-s-triazines, of
the
o-hydroxybenzophenones or of the oxalanilides, and
(as) further optional copolymerisable compounds.
Exemplary of ethylenically unsaturated organosilicon compounds are
vinylsilicon
compounds, allylsilicon compounds or silicon-containing (meth)acrylates. As
component
(al) it is preferred to use a compound of formula

~~e?~~f~~
_g-
(Y)n
CHi-C C- O-(- CH2 )3 --- Si
(Z)3-n
w
or
)
CHa=--C-C- O--~ CH2 )g ° Si ~ O-Si (Y)n (Z) g-n~
3-m
wherein n is 0-3, m is 0-3, R is H or CH3, Y is Ct-Cxalkyl and Z Ct-CBalkoxy
or
-OCH2CH20CH3. Exemplary of such compounds are:
1-[dimethyl-(3-acryloyloxypropyl)]-3-trimethyldisiloxane,
1-[dimethyl-(3-methacryloyloxypropyl)]-3-trimethyldisiloxane,
3-methacryloyloxypropyl-3-trimethoxysilane,
3-methacryloyloxypropyl-tris (trimethylsiloxy)silane.
The alkyl (methacrylates) used as component (a2) preferably contain an alkyl
radical of 1
to 12; more particularly 1 to S, carbon atoms. Illustrative of such compounds
are methyl
(rneth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl
(meth)acrylate, hexyl
(meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate or dodecyl
(meth)acrylate.
The hydroxyalkyl (meth)acrylates used as component (a3) preferably contain a
hydroxyalkyl radical of 2 to 6 carbon atoms. Illustrative of such compounds
are
2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl
(meth)acrylate or 2-hydroxyhexyl (meth)acrylate
As UV absorber component (a4) it is possible to use the same compounds as for
the
fluorine-containing compounds cited hereinbefore. Here too the derivatives of
2-(2-hydroxyphenyl)benzotriazole and of o-hydroxyphenyl-s-triazine are
preferred.

s.7 !" p
~;~.;:.~ ..n
-10-
As further copolymerisable compounds (component as) it is possible to use
typically
styrene, «-methylstyrene, acrylic acid, methacrylic acid, acrylonitrile ar
esters of malefic
acid. The copolymer also may contain as further copolymerisable compound (as)
a
copolymerisable sterically hindered amine. Illustrative examples of suitable
sterically
hindered amines are 2,2,6,6-tetramethylpiperidine-4-(meth)acrylate and
1,2,2,6;6-pentamethylpiperidine-4-(meth)acrylate.
The silicon-containing copolymer (a) will preferably comprise 5-40 % of
component (al),
30-70 % of component (a2), 5-20 % of component (a3), 0.5-10 % of component
(a4) and
0-30 % of component {a$).
Component (b) is a (meth)acrylic copolymer customarily used as binder for
coating
compositions. These copolymers are also called acrylic resins. They consist
mainly of one
or more alkyl acrylates or alkyl methacrylates and contain a minor amount of a
functional
aerylate or methacrylate. The (meth)acrylic polymer thus contains functional
groups
which are able to react, with crosslinking, with a suitable curing agent.
A great number of such acrylic resins are commercially available. It is
preferred to use an
acrylic resin which is a copolymer of several alkyl acrylates or alkyl
methacrylates, a
hydroxyalkyl (meth)acrylate and acrylic or methacrylic acid.
Component (c) is a curing agent which is able to react with the functional
groups of
components (a) and (b), It is preferred to use as curing agent a melamine
resin or a
polyisocyanate or a mixture of both.
The melamine resins suitable for use as curing agents are preferably N-
hydroxymethyl and
N-alkoxymethyl derivatives of melamine. Such melamine derivatives suitable for
use as
curing agents are commercially available and are conventionally used for
curing acrylic
resins.
Suitable polyisocyanate curing agents are preferably diisocyanates and
triisocyanates such
as toluene diisocyanate, diphenylmethane-4,4'-diisocyanate, hexamethylene
diisocyanate
or isophorone diisocyanate, and the dimerised, trimerised or capped
derivatives thereof.
The ratio of (a) to (b) may vary within a wide range. Preferably the weight
ratio of {a):{b)
is 20:80 to 80:20. The amount of curing agent (c) depends on the number of
functional

-11-
groups in (a) and (b). It is preferred to use 3 to 80 parts by weight of
curing agent per 100
parts of (a) and (b). In a preferred embodiment of the invention, the novel
mixture
comprises 30-50 % by weight of (a), 30-50 % by weight of (b) and 10-25 ~'/o by
weight of
(c).
The novel compositions can be used as binders for weather- resistant coating
compositions. In the simplest case, the coating compositions contain a mixture
of the
invention and a solvent. The coating compositions may be clear or pigmented
compositions. Suitable pigments may be inorganic, organic or metallic
pigments. The
viscosity of the coating compositions can be regulated by adding solvents or
thickeners.
The coating compositions may contain further modifiers such as fillers,
plasticisers,
levelling agents, adhesion promoters, accelerators, antioxidants or light
stabilisers. The
addition of light stabilisers selected from the class of the sterically
hindered amines is of
particular importance, as, together with the incorporated UV absorber of the
binder, these
compounds are able to effect a synergistic enhancement of weatherability.
Illustrative
examples of preferred sterically hindered amines are the derivatives of
2,2,6,6-tetramethylpiperidine described in Kunststoffe 77 (1987) 1065-69 or in
EP-A-156 52 on pages 5-17.
Depending on the curing agent used, these coating compositions can be cured at
room
temperature or at elevated temperature. In each case, curing is accelerated by
heating
(stoving). Acceleration can also be effected by adding curing catalysts. Thus,
for example,
curing with isocyanates can be accelerated by organotin compounds or by basic
catalysts
(for example tertiary amines). Curing with melamine resins can be accelerated
by acid
catalysts, for example by addition of toluenesulfonic acid.
The cured coating compositions are distinguished not only by excellent
weathering
resistance, but also by high gloss. Suitable substrates can be the customary
ones, such as
metal, wood, ceramic materials or plastics materials. If multilayer coats are
applied, the
coating compositions containing the binders of this invention are preferably
used as
topcoats, as they screen against UV radiation. The invention likewise relates
to the cured
finishes obtained with the novel coating compositions.
The following Examples illustrate the invention in detail. Parts and
percentages are by
weight.

s
J
-12-
Examples
Example 1: Preparation of a fluorine-containing copol
In a 400 ml autoclave fitted with stirrer, 25.24 g of cyclohexylvinyl ether,
14.42 g of
ethylvinyl ether, 11.61 g of hydroxybutylvinyl ether and 5.73 g of UV absorber
UV-1
HO t-C4H9
/ ~ ~ ~ ~ UV-1
O CI-Ig
II i
CH2CH2COOCH2CH(OH~H20-- C' C=CH2
are dissolved, under nitrogen, in 1 i0 g of tert-butanol, and 2 g of KZC03 and
0.1 g of
azoisobutyronitrile are added. To remove released air, the solution is
solidified by cooling
with liquid nitrogen. After warming to roam temperature, 58.24 g of
chlorotrifluoro-
ethylene are added, the autoclave is closed and heated slowly, with stirring,
to 65°C. This
temperature is kept for 7 hours and then cooled to room temperature. The solid
copolymer
is precipitated by pouring the resultant solution into water. It is washed
with water and
dried. The limiting viscosity [,~] of the copolymer is 0.30 dl/g. Elemental
analysis shows
that the copolymer contains 5 % of UV absorber.
Example 2: Example 1 is repeated, using as UV absorber 5.73 g of the compound
UV-2
HO t-C4H9
~ ~ / ~ uV-2
N
~CH2CH2C00 O-CO-CH=CH2
The copolymer obtained contains 5 % of UV absorber.
Example 3: Example 1 is repeated, using as UV absorber 5.73 g of the compound
UV-3

r.J ~ J
-13-
O CH3
OCH2CH(OH~H20--- CL- C=CH2
'OH
UV-3
CH3 N ~ N CH3
N/
r i
CHg CHg
The copolymer obtained contains 5 % of UV absorber.
Example 4: Example 1 is repeated, using as UV absorber 5.73 g of the compound
UV-4
HO
O O
C ~ ~ OCH2GH2O-C--CH=CH2 UV-4
The copolymer obtained contains 5 % of UV absorber.
Example 5~ Example 1 is repeated, using as UV absorber 5.73 g of the compound
UV-5
O
~I
C2H5 OCH2CH20- C - CHI CH2
O
NH-C-C-NH ~
UV-5
The copolymer obtained contains 5 % of UV absorber.

- 14-
Example 6: Preparation of a silicon-containing copolymer
A mixture of 90 g of xylene and 10 g of 4-methyl-2-pentanone is heated to
105°C. At this
temperature, a mixture of 10 g of 3-methacryloyloxypropylpentamethyl
disiloxane, 16.9 g
of styrene, 7.3 g of methyl methacrylate, 46.5 g of 2-ethylhexyl methacrylate,
16.2 g of
2-hydroxyethyl methacrylate, 3.1 g of methacrylic acid, 5.2 g of UV absorber
UV-1 and
0.7 g of azoisobutyronitrile is added dropwise over 4 hours. The mixture is
then stirred for
2 hours at the same temperature, to give a ca. 50 % solution of the copolymer.
The
copolymer contains 5 % of UV absorber in copolymerised form.
Example 7: Example 6 is repeated, using 5.2 g of compound UV-3 as UV absorber.
The
copolymer obtained contains S % of UV absorber.
Example 8: Example 6 is repeated, using 5.2 g of compound UV-4 as UV absorber.
The
copolymer obtained contains 5 % of UV absorber.
Example 9: Example 6 is repeated, using 5.2 g of compound UV-5 as UV absorber.
The
copolymer obtained contains 5 % of UV absorber.
Example 10: Prev~aration of clear coating compositions with melamine curing
agent
Mixtures are prepared from 19.5 parts of a copolymer which contains fluorine
and
UV absorber (product of Example 1), 19.5 parts of an acrylic resin (copolymer
of 31 % of
ethyl acrylate, 29.5 % of methyl methacrylate, 20.2 % of 2-ethylhexyl
methacrylate,
16.2 % of 2-hydroxyethyl methacrylate and 3.1 % of methacrylic acid, and 9.8
parts of a
melamine resin (Cymel~ 1130, Cyanamid Corp.) as curing agent. The mixtures
contain
ca. 2 % of UV absorber, based on solids. They are then diluted with xylene to
sprayable
consistency and applied to aluminium sheets coated with a silver metallic
primer lacquer.
The test pieces are stored for 1S minutes at room temperature and then stoved
for 30
minutes at 130°C. The finish so obtained has a film thickness of 40-45
wm.
A clear coating composition the fluorine-containing copolymer of which was
prepared as
described in Example 1, but without UV absorber, as well as the same
formulation to
which 2 % (based on solids) of UV-1 has been added, is used for comparison
purposes.
The formulation of the coating composition and the coating of the test pieces
are as
described above.
The cured test pieces are subjected to accelerated weathering in a UVCON~

-15-
Weather-O-Meter (with UVB-313 lamps) and in a xenon Weather-O-Meter {CAM 159,
KFA method). The 60° gloss according to DIN 67 530 is measured as the
criterion for
assessing damage.
Table 1- UVCON Weathering (8 h exposure at 70°C/4 h condensation
at 50°C)
60° gloss (in%) after
Stabiliser
0 400 1200 1600 h
without 87 40 15 -
2 % of UV-1 incorporated 94 84 54 37
(copolymer of Ex, 1)
2 % of UV-1 added 87 64 25 20
Table 2 - Xenon Weather-O-Meter
Stabiliser 60° gloss (%) after 800 h
without 18
2 % of UV-1 incorporated 49
(copolymer of Ex. 1)
2 % of UV-1 added 18
Example 11: Example 10 is repeated, using 19.5 parts of the copolymer of
Example 3 in
place of the copolymer of Example 1. The clear coating composition contains
ca. 2 % of
UV-3, based on solids.
The test pieces are coated as described in Example 10 and tested in a CAM 159
xenon
Weather-O-Meter and by measuring the 60° gloss in accordance with DIN
67 530.

-16-
Table 3 - Xenon Weather-O-Meter
Stabiliser 60° gloss (%) after 800 h
without 18
2 % of UV-3 incorporated 42
(copolymer of Ex. 3)
2 % of UV-3 added 19
Example 12: Mixtures are prepared from 19.5 parts of the silicon-containing
copolymer of
Example 6, 19.5 parts of the acrylic resin used in Example 10; and 9.8 parts
of melamine
resin (Cymel~1130) as curing agent. The mixtures contain ca. 2 % of UV
absorber, based
on solids.
A mixture prepared by using a silicon-containing copolymer which does not
contain UV
absorber as comonomer, but which has otherwise been prepared as described in
Example
6, is used for comparison purposes.
The test pieces are coated and tested as described In Example 10. The results
are reported
in Table 4.
Table 4 - Weathering in a xenon Weather-O-Meter
Stabiliser 60° gloss (%) after 2000 h
without 40
2 % of UV-1 incorporated 52
(copolymer of Ex. 6)
2 % of UV-3 incorporated 60
(copolymer of Ex. 7)
Example 13' Clear coating composition with isocyanate curing went
Mixtures are prepared from 19.5 parts of the fluorine-containing copolymer of
Examples 1
and 3, 19.5 parts of the acrylic resin described in Example 10, and 5.2 parts
of an alipharic

~~~~~~~~f~
-17-
triisocyanate (Desmodur~ N 75, Bayer A.G.). The mixtures contain ca. 2.2 % of
UV
absorber, based on solids.
The mixtures are diluted with xylene to sprayable consistency and applied to
aluminium
sheets coated with a silver metallic primer lacquer. The test pieces are air-
dried for 15
minutes at room temperature and then cured for 45 minutes at 80°C. The
finish so
obtained has a film thickness of 40-45 wm.
A coating composition the fluorine-containing copolymer of which has been
prepared as
described in Example 1, but without UV absorber as cornonomer, is used for
comparison
purposes. Further, to this formulation is added once 2.2 % of UV-1 and once
2.2 % of
UV-3. The results obtained after subjecting the test pieces to weathering for
1200 hours in
the UVCON Weather-O-Meter (8 h exposure at 70°C, 4 h condensation at
50°C) are
reported in Table 5.
Table 5 - Weathering in UVCON Weather-O-Meter
Stabiliser 60° gloss (%) after 1200 h
without 9
2 % of UV-1 incorporated 78
(copolymer of Ex. 1)
2 % of UV-1 added 46
2 % of UV-3 incorporated 63
(copolymer of Ex. 3)
2 % of UV-3 added 16
Example 14: A mixture is prepared from 19.5 parts of the silicon-containing
copolymer of
Example 7, 19.5 parts of the acrylic resin used in Example 10, and 5.2 parts
of
Desmodur~ N75. The mixture contains ca. 2.2 % of UV-3 in copolymerised form.
In the same manner, a mixture is prepared whose silicon-containing copolymer
has been
prepared as described in Example 7, but without UV absorber as comonomer. This
mixture is used once without and once with addition of 2.2 % of UV-3 (based on
solids).

~~~5~~
- is -
The coating of the test pieces and testing in the UVCON Weather-O-Meter ($h
exposure
at 70°C, 4 h condensation at 50°C) are as described in Example
10. The results are
reported in Table 6.
Table 6 - Weathering in UVCON Weather-O-Meter
Stabiliser 60° gloss (%) after 2000 h
without 22 (cracking)
2 % of UV-3 incozporated 47
(copolymer of Ex. 7)
2 % of UV-3 added 24