Note: Descriptions are shown in the official language in which they were submitted.
r~ ~ ~ 3~f~
Coatin~ aaents for transparent coatinq-lac~uer layers and use
thereof in methods of producinq multilaver coatin~s
The invention relates to coating agents for transparent
stoving multilayer coatings for lacquering of mass-produced
cars and characterised by high acid rain resistance and a high
content of solids for processing.
JP patent publication number 1(1989)-158079 describes coating
agents based on caprolactone-modified polyacrylate resins,
optionally also containing hydroxyalkyl(meth~acrylates,
alkylated melamine resins and optionally blocked
polyisocyanates. These coating agents can be used to produce -
high-solid car lacquer coats, but the level of acid rain
resistance required in industry is not reached. The lacquers
tend to turn yellow and have low initial gloss.
GB-A-2 254 328 and JP patent publication 5 025 431 describe ~ ~
coating agents comprising hydroxy-functional polyacrylate ~.s~ ~ `
resins and polyester resins, alkylated melamine resins and
hexamethoxy methyl melamine resins, blocked acid catalysts and
blocked polyisocyanates, which admittedly have high resistance i~
to acid but have a low content of solids for processing. ~-
Also, these lacquers are not resistant to yellowing and their
initial gloss is unsatisfactory.
JP patent publication number 4(1992)-246483 differs from
GB-A-2 254 328 in that the coating composition additionally
contains a catalyst in the form of organotin compounds.
DE-A-42 04 518 describes non-aqueous transparent coating
lacquers based on hydroxyl group-containing synthetic resins, - -
aminoplastic resins and blocked polyisocyanates, the latter
being blocked with dialkyl malonates or with oximes or
blocking agents containing methylene groups. As before, the
- '~1 3~3~:~.2
acid resistance of the resulting lacquer coats is not
completely satisfactory. ;
The aim of the invention is to provide coating agents for
multi-layer stoving coatings, the agents being suitable for
lacquering of mass-produced cars and also having a high
content of solids for processing and improved resistance to
acid rain, which is shown analytically by high resistance to
sulphuric acid. ~-~
It has been found that the requirement for coating agents
resistant to sulphuric acid and also with a high solid content
can be met by means of coating agents containing one or more
hydroxy-functional (meth)acrylic copolymers in addition to
blocked polyisocyanates, aminoplastic resins, conventional
lacquer additives and solvents, and optionally one or more ~ -
hydroxy-functional polyesters.
! . . ~
The invention therefore relates to the aforementioned coating ~ -
agents, in which the binders contain~
A) 25 - 90 wt.~ of one or more hydroxy-functional
I (meth)acrylic copolymers, obtainable from - ~ -
¦ al) 10 - 30 wt.~ styrene and/or one or more styrene
derivatives
a2) 20 - 40 wt.~ of one or more glycidyl esters and/or
vinyl esters of alpha, alpha'-dialkyl-
substituted branched aliphatic
monocarboxylic acids,
. . .
a3) 5 - 15 wt.~ of one or more hydroxyalkyl esters of
(meth)acrylic acid, -
. ;.'
a4) 1 - 15 wt.~ of (meth)acrylic acid,
;'~
. '
. ;,
2 1 3 '~
a5) 15 - 35 wt.% of one or more (meth)acrylic acid esters,
'.'~ :'',) 0 - 40 wt.%, preferably 10 to 30 wt.% of one or more
hydroxy-functional (meth)acrylic
copolymers, obtainable from
bl) 5 - 20 wt.~ styrene and/or one or more styrene ~;
derivatives,
., . .,, ~ , . .
b2) 5 - 20 wt.~ caprolactone, i~ -
b3) 10 - 30 wt.% of one or more hydroxyalkyl esters of
(meth)acrylic acid, -~
b4) 1 - 3 wt.% (meth)acrylic acid,
b5) 30 - 50 wt.% of one or more (meth)acrylic acid esters,
C) 0 - 40 wt.%, preferably 10 to 30 wt.% of one or
more hydroxy-functional polyesters,
D) 5 - 35 wt.~ of one or more blocked polyisocyanates
and ;
E) 5 - 30 wt.% of one or more aminoplastic resins,
the sum of components al) to a5), bl to b5) and A to E) being
100 in each case.
The (meth)acrylic copolymers in the coating agents according
to the inventio~ can be manufactured by radical
copolymerisation by conventional methods. The solution
polymerisation method is preferred for synthesis of the
(meth)acrylic copolymers (components A and B) used in the
coating agents according to the invention. In this method the
solvent is placed in the reaction vessel, heated to boiling~
..
., .~.
~ 1 3 S '~
point, and the mixture of monomers and initiators is added ~-
continuously during a predetermined time.
The term "(meth)acrylic" used in the present description and
claims is synonymous for "acrylic and/or methacrylic".
Polymerisation is brought about e.g. at temperatures between
80C and 160C, preferably 100C to 150C.
r-
The polymerisation reaction can be started with known
polymerisation initiators, e.g. per- or azo-compounds which
thermally decompose into radicals in a first-order reaction.
The nature and amount of initiator are chosen so that a
substantially constant supply of radicals is available at the
polymerisation temperature during the intake phase. `-
The following are examples of initiators preferably used for
polymerisation: dialkyl peroxides such as di-tert.-butyl
peroxide, di-cumyl peroxide; diacyl peroxides such as di-
benzoyl peroxide, di-lauroyl peroxide; hydroperoxides such as
cumene hydroperoxide, tert. butyl hydroperoxide; peresters
such as tert. butyl perbenzoate, tert. butyl perpivalate, ~ ~
tert. butyl-per-3,5,5-trimethyl hexanoate, tert. butyl-per-2- ~ `;
ethyl hexanoate; peroxydicarbonates such as di-2-ethyl hexyl
peroxydicarbonate, dicyclohexyl peroxydicarbonate; perketals
such as 1,1-bis-(tert. butylperoxy)-3,5,5-trimethyl -
cyclohexane, 1,1-bis- (tert.butylperoxy)cyclohexanei ketone ~ -
peroxides such as cyclohexanone peroxide or methyl isobutyl
ketone peroxidei azo compounds such as 2,2~-azo-bis(2,4-
dimethyl valeronitrile), 2,2'-azo-bis-(2-methyl
butyronitrile), 1,1'-azo-bis-cyclohexane carbonitrile or azo-
bis-isobu~yronitrile. `~
Preferably the polymerisation initiators, more particularly
the peresters, are added in a proportion of 0.2 to 5 wt.~ of
the weighed-in quantity of monomers.
-` 21 3 ~ ~ ~ 2
The organic solvents advantageously used in solution ~.
polymerisation are conventional lacquer solvents, such as can
also be used later ln the coating agents according to the
invention, e.g. glycol ethers such as ethylene glycol dimethyl
ether; glycol ether esters such as ethyl glycol acetate, butyl
glycol acetate, 3-methoxy-n-butyl acetate, butyl diglycol
acetate, methoxypropyl acetate, esters such as butyl acetate, ---
isobutyl acetate, amyl acetate; or ketones such as methyl `- -~
ethyl ketone, methyl isobutyl ketone, diisobutyl ketone,
cyclohexanone or isophorone. Alcohols such as methanol,
ethanol, propanol, butanol, aromatic hydrocarbons such as ~`
xylene, Solvesso 100 (registered trade mark for a mixture of
aromatic hydrocarbons with a boiling range of 155 to 185C) ~ :
and aliphatic hydrocarbons can also be used, blended with the
aforementioned solvents.
In order to adjust the molecular weight, particularly in the .
preferred solution polymerisation, use can be made of chain
transfer agents such as mercaptans, thioglycolic acid esters,
chlorinated hydrocarbons, cumene or dimeric alpha-methyl
styrene. ~ .
The polymerisation conditions (reaction temperature, intake
time of the monomer mixture, concentration of solvent) are
adjusted so that the (meth)acrylic copolymers for the coating
agents produced according to the invention have a weight ~ :~
average molecular weight (determined by gel permeation
chromatography using polystyrene as a calibrating substance)
of 2500 - 10000.
~ ' :
The hydroxyl group-containing (meth)acrylic copolymers in the :
coating agents produced according to the invention are
preferably situated in a glass transition temperature range of
-20C to +40C, calculated from the glass transition
temperature of the homopolymers of the individual monomers as
given in the literature (Fox equation, see e.g. Polymere
Werkstoffe, Batzer, 1985, page 307). .
:' ~
. ' :~-
1 3 ~ 2
The monomers for producing the hydroxy-functional(meth)acrylic
copolymers (component A) and used as component a2) are e.g.
glycidyl and/or vinyl esters of alpha, alpha'-dialkyl-
substituted branched aliphatic monocarboxylic acids (e.g. the -~ ;
commercial products CARDURA E10 and VEOVA 10 produced by Shell
AG). The other monomers for producing (meth)acrylic
copolymers (components A and B) are e.g. styrene and/or
styrene derivatives, such as vinyl toluene, p-methyl styrene
or p-tert. butyl styrene, hydroxyalkyl esters of acrylic acid `~
or methacrylic acid such as beta-hydroxy-ethyl acrylate, beta-
hydroxyethyl methacrylate, beta-hydroxypropyl acrylate, beta- ~ -
hydroxypropyl methacrylate, butanediol-1,4- monoacrylate,
butanediol-1,4-monomethacrylate, hexanediol-1,6-monoacrylate
or hexanediol-1,6-monomethacrylate. Alternatively, at least
partial use can be made of polyalkylene oxide -
mono(meth)acrylates with 2 to 10 alkylene oxide units per
molecule, or alkyl esters of acrylic acid or methacrylic acid; -
methacrylates, methyl methacrylate, ethyl acrylate, ethyl
methacrylate, isopropyl methacrylate, tert. butyl acrylate, ~ ~
n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, ; ~ -
isobutyl methacrylate, cyclohexyl methacrylate, trimethyl
cyclohexyl methacrylate, 2-ethyl hexyl acrylate, 2-ethyl hexyl
methacrylate, lauryl acrylate, lauryl methacrylate, stearyl
acrylate, stearyl methacrylate, isobornyl acrylate or
isobornyl methacrylate.
In order to provide the (meth)acrylic copolymers A) and B)
with carboxyl groups, (meth)acrylic acid is incorporated by
polymerisation, preferably in quantities such that the
resulting acid number is 1 to 30 mg KOH/g. In order to
introduce hydroxyl groups into the (meth)acrylic copolymers A)
and B), hydroxyalkyl esters of (meth)acrylic acid (a3 to b3)
are used preferably in quantities such that the resulting
hydroxyl numbers are 40 to 200 mg KOH/g. ;~
The polyesters optionally used as component C) are
polycondensation products of polyvalent polycarboxylic acids ~-
2 1 3 ~ ~ 1 2
(e.g. dicarboxylic acids) or anhydrides thereof or polyhydric
polyols, optionally also using monocarboxylic acids. These
polymers are usually prepared with an excess of alcohol. The
OH numbers are e.g. about 30 to 200, preferably 60 to 160 mg ~ - -
KOH/g. The acid numbers are e.g. 1 to 50, preferably 5 to 30. --
The weight average molecular weight is e.g. 500 to 4000, i~
preferably 1000 to 2000 g/mol. The following are examples of
suitable polycarboxylic acids: o-phthalic acid (anhydride)
isophthalic acid, terephthalic acid, tetrahydrophthalic acid
(anhydride), 1,2-cyclohexane dicarboxylic acid (anhydride),
1,3-cyclohexane dicarboxylic acid, 1,4-cyclohexane
dicarboxylic acid, 4-methyl hexahydrophthalic acid
(anhydride), endomethylene tetrahydrophthalic acid
(anhydride), trimellitic acid (anhydride), succinic acid
(anhydride), glutaric acid, adipic acid, azelaic acid, sebacic
acid, butane tetracarboxylic acid or dimeric fatty acid.
The polyesters can also contain small proportions of condensed `~
maleic acid anhydride. Optionally the aforementioned
polycarboxylic acids can be used together with natural or
synthetic monocarboxylic acids such as benzoic acid, tert.
butyl benzoic acid, lauric acid, isononanoic acid or fatty
acids from naturally-occurring oils.
The following are examples of suitable alcohol components for
preparing the polyesters: diols such as ethylene glycol, ;~
diethylene glycol, triethylene glycol, polyethylene glycols,
propanediols, polypropylene glycols, butanediols, hexanediols,
neopentyl glycol, cyclohexane diol, cyclohexane dimethanol,
trimethyl pentane diol, ethyl butyl propane diol, or
polyvalent alcohols such as trimethylol ethane, trimethylol
propane, di-trimethylol propane, glycerol, pentaerythritol, ;~
di-pentaerythritol or tris-hydroxyethyl isocyanurate. -
The polyesters can contain a modification component in the
form of glycidyl esters of alpha, alpha~-di-substituted -~
monocarboxylic acids and epsilon caprolactone.
:,'. ~...`-
Component D) in the coating agents according to the invention
comprises blocked aliphatic or cyclo-aliphatic polyisocyanates
in conventional use in the lacquer sector, e.g. diisocyanates
such as isophorone diisocyanate, hexamethylene diisocyanate or
1,3- dimethyl-cyclohexyl-1,3-diisocyanate. Other examples of
aliphatic or cycloaliphatic polyisocyanates are biuret group- ~ -
containing products of a reaction between 3 mols of
hexamethylene diisocyanate and one mol of water, with an NCO ;
content of about 22%; isocyanurate group-containing poly-
isocyanates prepared by trimerisation of 3 mols of
diisocyanate, e.g. hexamethylene diisocyanate or isophorone
diisocyanate trimers, or urethane group-containing poly-
isocyanates, obtained by a reaction between 3 mols of
diisocyanate and 1 mol of triol. Isophorone diisocyanate
trimers are preferably used.
The blocking agents can be conventional CH acids, NH- or OH-
functional compounds, which bring about cross-linking under
the hardening conditions, e.g. CH-acid esters such as aceto-
acetic alkyl esters, malonic acid dialkyl esters, epsilon
caprolactam, alcohols such as tert. butanol or oximes such as
methyl ethyl ketoxime. Malonic acid dialkyl esters and oximes
are preferred. It may be advantageous simultaneously to use
various masking agents, either inside a polyisocyanate
molecule or in a mixture.
It has been found that the coating agents of the invention provide
particularly light and essentially yellowing-free coatings, if blocked ~ h
polyisocyanates are used as component û) which are prepared by reaction of `:~ ~ .
free isocyanates under water-free conditions with blocking agents containing ;~
acid hydrogen, in the presence of basic catalysts, wherPin one or more
alkali hydroxides are used as .basic catalysts. The thus obtained blocked ~ `:-
polyisocyanates.have a particularly low alkali content due to the use of :-:
:: .....
: ~;:
:
-" 21~ 112
g ~ ., . . ~ ~. .
basic catalysts. Said content is preferably less than 100 ppm,
particularly preferably less than 80 ppm and less than 50 ppm,
calculated ad the weight of the alkali metals and based on the weight
of the blocked isocyanates. `
.,:: ~ ~;.
The above mentioned process can be applied to any isocyanates with free
isocyanate functions. It is, e.g. possible to use the above mentioned
polyisocyanates.
.:
Know blocking agents containing acid hydrogen may be used for the above
mentioned preparation of the polyisocyanates, e.gO the blocking agents
examplified above. Specific examples are dialkyl malonic esters and
alkyl acetoacetic esters. The alkyl groups of the esters, which in the
dialkyl malonic ester may be the same or different, have preferably 1
to 4 carbon atoms.
When preparing the polyisocyanates as explained above, the
molar ratio of the blocking agents containing acid
hydrogen to the NCO groups of the isocyanates, for example, ~ .
the ratio of the dialkyl malonic esters and/or alkyl
acetoacetic esters to NCO groups may range, for example,
from 0.5:1 to 1:1.5. In the case of an NCO excess, the
free NCO groups may optionally be reacted with other
reactants. ~ ~-
The catalysts used for the above explained process are
alkali hydroxides, for example, alkali metal
hydroxides such as lithium, sodium and/or potassium
hydroxide. The water-free alkali metal hydroxides are used
in preference. Lithium hydroxide is used in particular
preference. The catalysts are used in catalytic .
quantities, for example, in quantities o, 0.1 to 2~ by wt., ~ -~
preferably 0.3 to 1~ by wt., based on the weight or
isocyanate and blocking agent.
",
2 ~ 3, '' 1 2
, ~
.
The catalysts are used in solid form, for exam?le, in the
form of a powde~
The addition of the blocking agent to the isocyanat- is ~-
ca-ried out under wate--free conditions, pref~rably wlth
the careful e:cclusion of moisture. The ~_~ctlon may be
ca-ried out, for example, under a dry i.e-. cas, such as
nitrogen. -
The reaction may take place without solvents or in the
presence of organic solvents. Suitable solvents a-=, in
particular, those that do not react with polyisocya~at-s.
Examples of such solvents are orcanic solvents, suc:~ as
ali?hatic and aromatic hydrocarbor.s, for ecample, x~lene,
mix.ures of aliphatic and/or aromatic hvc-oca-bons, es.e~s
and ethers.
In the process described above it is possible,
after the reaction has ended, to remove easily the catalyst
that remains undissolved in the reaction medium. This may
be carried out, for example, by filtering or centrifuging.
optionally, the reaction product may be diluted beforehand
or afterwards with solvents. In this case, solvents that
can react with free polyisocyanates may also be used.
Suitable solvents are organic solvents, particularly
solvents customary in lacquers, such as aromatic
hydrocarbons, for example, xylene, aliphatic hydrocarbons,
for example, n-hexane or cyclohexane, mixtures of aliphatic
and/or aromatic hydrocarbons, ketones such as, for example,
acetone, methylisopropyl ketone, esters such as, for
example, butyl acetate or ethyl acetate, ethers such as,
for example, methoxypropanol or butoxypropanol. ~lcohols,
such as, for example, isopropanol or hexanol, may, however,
also be used.
. - . ....................................... .
. .: ~ . . .
2 ~ 3 ~ ~ 1 2
The coating agents used according to the invention contain
cross-linking agents such as aminoplastic resins (component
E). The aminoplastic resins used can be conventional cross~
linking agents in the lacquer sector. Suitable aminoplastic
resins include e.g. alkylated condensates obtained by reaction `~
o~ amino triazines and amido triazines with aldehydes. They
are manu~actured by known methods by condensing amino or
amido-group containing compounds such as melamine,
benzoguanamine, dicyanodiamide, urea or N,N-ethylene urea in
the presence of alcohols such as methyl, ethyl, propyl,
isobutyl, n-butyl or hexyl alcohol with aldehydes,
~'~ .::~ ' ' ,
; ~.,
, ,:i .i ~: . -
.,. ~ ii.~, .
' ';.~-' .',-' ., "
, ., . ~ ",, j,
. ~ ., .
.," ~ .~,"
~ . -: :~ ..
,',' '"''.-.- -
,.~
~ ..
.. , ~ -:: :
12 2~ ~5 ~2
particularly formaldehyde. The reactivity of these amine
resins is determined by the degree of condensation, the ratio
of the amine or amide component to the formaldehyde and the
nature of the etherification alcohol used.
The coating agents containing the binders for use according to
the invention can contain the aforementioned solvents together
with conventional lacquer adjuvants such as levelling agents,
e.g. based on (meth)acrylic homopolymers, silicone oils,
plasticisers such as phosphoric acid, phthalic acid or citric -
acid esters, substances for influencing the flow properties,
such as pyrogenic silicone oxide, microgels, urea group- -
containing products obtained by a reaction between primary ~f
amines and polyisocyanates, hydrogenated castor oil, curing ;~
accelerators for reacting the hydroxyfunctional binders
according to the invention (components A, B and C) with
blocked isocyanates (component D) and aminoplastic resins
(component E); phosphoric acid, phosphoric acid esters,
dicarboxylic acid semiesters, citric acidi organic metal salts
such as dibutyl tin dilaurate, zinc naphthenate, bismuth
tricarboxylate, or tertiary amino group-containing compounds
such as triethylamine and light-excluding agents.
The coating agents according to the invention are particularly `
suitable for producing a transparent top layer during the
manufacture of stoving multi-layer coatings. The top layer
can be applied by the wet-on-wet method, when both layers are
hardened simultaneously. The invention therefore also relates
to the method of producing multi-layer coatings or using the
coating agents for manufacturing them. The solvent-containing
coatings according to the invention can be applied in the form
of a transparent top lacquer on layers of aqueous or solvent-
containing base lacquers for hardenable multi-layer coatings. ;
The coating agents according to the invention are applied by ~ ~
known methods such as spraying, immiersion, rolling or doctor ~`
blade. The top-lacquer layer is applied to the substrate, ~
-~` 21~5`~2 -:
13
which is optionally already covered with other lacquer layers. ~ ;
The coating agents according to the invention can also be
applied by spraying, using supercritical carbon dioxide as a ~ ~-
solvent. The content of organic solvents can be greatly
reduced. After an evaporation phase, the applied coating
agent is cross-linked, preferably by heating. The stoving
temperatures are usually between 110 and 160C, preferably
between 120 and 150C. The thickness of the stoved film is
about 15 - 50 ~m. The result is a cross-linked, hard, glossy
lacquer coating. One preferred embodiment is use o~ the
coating agent according to the invention as a clear lacquer
coating on a base lacquer. Operation can be wet-on-wet, or
alternatively the base lacquer is previously dried by heating.
This results in particularly good adhesion between the two
layers.
Coating agents formulated as clear lacquers according to the
invention can be applied e.g. over base lacquers, which can
contain conventional coating-lacquer pigments, preferably
decorative pigments such as metallic pigments. The binder
bases of the base lacquer preferably comprises polyester,
polyurethane or acrylate resins. These binders can optionally
be cross-linked by cross-linking agents, e.g. melamine or
isocyanate derivatives.
The coating agents according to the invention are particularly
suitable for top lacquers or clear lacquers, preferably for
use in the motor-vehicle sector but also in other areas. The
use of the coating agent according to the invention for multi~
layer lacquering is particularly suitable for lacquering mass-
produced motor vehicles, but uses are also possible for other
purposes, such as domestic appliances or for the furniture
industry.
The coating agents according to the invention are particularly
suitable for manufacturing a transparent top layer of a ~ ;
~ ~ 3 ~
14
stoving multi-layer coating. They are particularly suitable
for lacquering of mass-produced car bodies and parts thereof.
The coating agents according to the invention can be applied -
wet-on-wet on conventional, i.e. solvent-containing or
aqueous, lacquer layers, when both layers are simultaneously
hardened at elevated temperature. For example, transparent
top layers applied to the clear lacquers according to the
invention can be applied by the wet-on-wet process on
conventional or aqueous base lacquers. The two layers can
then be hardened simultaneously. The hardening temperatures
are e.g. of the order of 120 to 150C. The hardening times
are e.g. of the order of 20 to 40 minutes.
Accordingly the invention also relates to manufacture of
multi-layer coatings or use of the coating agents according to
the invention for producing top lacquer layers, e.g. clear -~ -
lacquer layers, for hardenable multi-layer coatings. ~ ;
The following examples illustrate the invention. A11 parts
are by weight.
Manufacture of the (meth)acrylic copolymers
: :
Example of manufacture AC-1
173 g of SOL~ESSO 150 (product sold by Shell AG) and 5 g of ~ 0
n-butanol were placed in a 2-litre 3-necked ground-glass flask
equipped with an agitator, contact thermometer, globe-shaped
condenser and dropping funnel, and were heated to 152C with
agitation, after switching on the reflux condenser. During -
six hours, a mixture of 67 g acrylic acid, 160 g styrene,
150 g butyl acrylate, 65 g 2-hydroxyethyl acrylate, 220 g
CARDURA E10 (product sold by Shell AG), 16 g di-tert. butyl
peroxide and 22 g tert. butyl. peroctoate were continuously
added. Next, the batch was additionally polymerised at 150C
:: ~
. . ; ~ ''`~`
2l3~2
for 4 hours, cooled to 80C and diluted with 62 g Solvesso 100
and 62 g n-butanol. ~ .
Example of manufacture AC-2
163 g SOLVESSO 150 (product sold by Shell AG), 5 g n-butanol ~ ~ -
and 70 g VEOVA 10 (product sold by Shell AG) were placed in a - -~
2-litre 3-necked ground-glass flask equipped with an agitator,
contact thermometer, globe-shaped condenser and dropping
funnel, and were heated to 152C with agitation, using a
reflux condenser. A mixture of 47 g acrylic acid, 160 g
styrene, 125 g butyl methacrylate, 110 g 2-hydroxyethyl
methacrylate, 150 g CARDURA E10 (product sold by Shell AG),
16 g di-tert. butyl peroxide and 22 g tert. butyl peroctoate
was continuously added during 5 hours. The batch was then
additionally polymerised at 152C for 5 hours, cooled to 80C
and diluted with 72 g Solvesso 100 and 60 g n-butanol.
Example of ma~ufacture AC-3
232 g SOLVESSO 100 (product sold by Shell AG) was placed in a
2-litre 3-necked ground-glass flask equipped with an agitator,
contact thermometer, globe-shaped condenser and dropping
funnel, and heated to 148C with agitation, after switching on
the reflux condenser. A mixture of 14 g acrylic acid, 65 g
styrene, 224 g butyl methacrylate, 141 g 2-hydroxypropyl
methacrylate, 45 g 2-hydroxyethyl acrylate, 52 g lauryl
acrylate, 89 g caprolactone, 4 g di-tert. butyl peroxide and
16 g tert. butyl peroctoate was continuously added during
5 hours. The batch was then additionally polymerised at 148C
for 5 hours, cooled to 80C and diluted with 46 g Solvesso 100
and 72 g n-butanol.
Example o~ ma~u~acture AC-4
185 g of SOLVESSO 100 (product sold by Shell AG) and 5 g
butanol were placed in a 2-litre 3-necked ground-glass flask
.. . :. .
16 213 ~ '1 12
equipped with an agitator, contact thermometer, globe-shaped
condenser and dropping funnel, and heated to 152C with
agitation, after switching on the reflux condenser. A mixture
of 67 g acrylic acid, 160 g styrene, 84 g butyl acrylate, 87 g
2-hydroxyethyl acrylate, 220 g CARDURA E10 (product sold by
Shell AG), 16 SOLVESSO 100 (product sold by Shell AG), 16 g
di-tert. butyl peroxide and 16 g tert. butyl peroctoate was
continuously added during 5 hours. The batch was then
additionally polymerised at 148C for 5 hours, cooled to 80C
and diluted with 79 g SOLVESSO 100 and 65 g n-butanol. -~
~r ~ ~ ~
Example of manufacture PE~
170.3 g hexanediol-1,6 and 128.9 g trimethylol propane was
placed and melted in a 2-litre 3-necked flask equipped with a
thermometer, agitator and condenser. Next, 0.3 g of ~`
hypophosphorous acid, 37 g xylene, 228.2 g hexahydrophthalic
acid anhydride and 278.6 g dimeric fatty acid was poured in
with agitation, heating and under a stream of inert gas, and
heated to 220C at the rate of 20C per hour. After an acid
number of 22 had been reached, the mixture was cooled to 100C
and diluted with 156 g Solvesso 100 (product sold by Shell ~;
AG).
. ~:
Exam~le 1
Manufacture of a clear lacouer
, ~,
A single-component clear lacquer was manufactured by
homogeneous mixing of 24.4 parts of the resin solution in
Example AC-3 with 28 parts of the resin solution in Example
AC-1, 10.75 parts Solvesso 100, 7.5 parts of a 70% butyl
glycolic solution of the isocyanurate of isophorone
diisocyanurate blocked with butanone oxime, 3 parts butanol,
16.6 parts of a commercial 58% solution of a highly reactive
butanol-etherified melamine resin in butanol/xylene, 3.2 parts ~ ~
of butyl glycol acetate, 1.2 parts of a 1 : 1 mixture of ~;
' ' ' ~ ' ':
.,,, ~-.~ -
17 ~ 2
commercial light-excluding agents based on benzotriazole and
HALS, 1 part of silicone oil, 0.35 parts o~ dibutyl tin ~ :.
dilaurate and 4 parts of butyl diglycol. -~
Exam~le 2
Manufacture ~f a clear lacouer
In the same manner as in Example 1, a single-component clear
lacquer was produced from 31.6 parts of the resin solution in
Example AC-1, 13.8 parts of the resin solution in Example
PE-1, 20.2 parts of a commercial 70~ butanolic solution of a
melamine resin co-etherified with methanol and butanol, 11.7
parts of a solution of the blocked polyisocyanate from clear- :~
lacquer example 1, 11.24 parts of Solvesso 100, 1.2 parts of
the light-excluding agent mixture in clear-lacquer example 1,
0.8 parts butanol, 3.3 parts butyl glycol acetate, 1 part of `~
silicone oil, 0.76 parts of dibutyl tin dilaurate and 4.4 - -~
parts of butyl diglycol.
Example 3
Manufacture of a clear lacouer
In the same manner as in Example 1, a single-component clear
lacquer was produced from 46.2 parts of the resin solution in ;~
example AC-4, 13.5 parts Solvesso 100, 7.1 parts of a
commercial 70~ butanolic solution of a melamine resin co- ~.;
etherified with methanol and butanol, 2'.4 parts of a 70
Solvesso 100 solution of an isocyanurate of isophorone
diisocyanate blocked with malonic acid:diethyl ester, .
1.2 parts of the light-excluding agent mixture in clear-
lacquer example 1, 0.84 parts of butanol, 3.5 parts of butyl
glycol acetate, 1 part of silicone oil, 0.76 parts of dibutyl
tin dilaurate and 4.5 parts of butyl diglycol.
` ` !
''; ~'''
18 2t3~2
Sheet-metal bodies previously coated with commercial
cathodically depositable electrodeposition lacquers (KTL)
conventionally used for lacquering mass-produced cars (KTL;
18 ~m) and commercial fillers (35 ~m) were lacquered with
commercial water-dilutable metallic-based lacquer in a dry .
layer thickness of 15 ~m and pre-dried at 80C for 6 minutes.
Directly afterwards, the clear lacquer in clear-lacquer
examples 1, 2 and 3 was applied by spraying wet-on-wet in a
dry layer thickness of 35 ~m and stoved at 140C (the object
temperature) for 20 minutes after 5 minutes' ventilation at
room temperature.
Corresponding comparative experiments were made with prior-art
lacquers. The results are given in the following Table. The
tests were carried out in accordance with general industrial
standards. The clear lacquers were tested for resistance to
sulphuric acid by the drop test, using 10% and 38% H2SO4 ~- -
respectively. The metal test sheets were placed on a heatable
plate and heated to 65C. Care was taken that the sheets
rested flat, to ensure optimum transmission of temperature. ~;~
At the end of the heating-up phase, i.e. at 65C, one drop per
minute was applied to the clear-lacquer surface. The total
time was 30 minutes. At the end of the test time, the lacquer
was washed off with water. When necessary, a brush could
additionally be used for cleaning.
In order to judge the resistance to sulphuric acid, the period
of action, in minutes, is given at which the first visible ;~
change in the film (swelling) damage (dulling) or corrosion of
base lacquer occurs.
, ., :,
''.'.'.'.
',. '~;",' .' ''
~ ~ 3 ~ l~ '1 2
19
: ,
. ~ .
Table
Clear lacquers according to the invention~
ExamDle: 1 2 3 .'''~'~',',7 ''
Yellowing: _ None_ Slight None _ " -
Content of solids for
~rocessing (%) 47.1 51.2 48.1
20qloss 84 _ 88 88
Pendulum hardness~
(Number of vibrations) 75 77 84 ~-.
Sulphuric acid test
10% H2S04, 30'60C
Swelling 13 17 14
Dulling 21 22 30
Corrosion of base coat 24 30 ~30
Sulphuric acid test :~
, 0 0 ~ ~ 0 ~
~ O A2 C~ V4, ~ u ~, v
Swelling 20 11 13
Dulling ,30 ~30 28
Corrosion of base coat 28 30 >30 ,~
Pencil hardness: HB HB HB
;" .~ ','`;~'''
Clear lacquers used for comparison
JP-A GB-A JP-A DE-A
. " ~
246483 2254328 158079 4204518 : ~;
Example 2 4 1 7
Yellowing: Sliaht Strong Stronq None
Contents of.
solids for
processinq (%) 32.4 41.5 58.1 50.8
20gloss 83 58 29 82
:. ~ ..: . :~.: .......
" ,,
.. ;.-.-., .~
.. , ,: . . ~,
: .. . ..: .
2 ~ 3 ;~
Pendulum hardness
(number of
vibrations) 84 85 38 82 ~ ~ ~
Sulphuric acid ~ ~-
test
10~ H2SO4, 30'60C
Swelling 14 12 10 10
Dulling ~30 ,30 13 13
Corrosion of
base coat 22 18 19 19
Sulphuric acid
test ;~
39~ H2SO4, 30'60C
Swelling 9 2 2 5
Dulling ~30 11 11 11
Corrosion of
base coat 25 15 15 13 -
Pencil
hardness HB F 2B HB _ ~ '
As the preceding Table shows, the coating agents according to
the invention, as compared with JP-A-246 483, are
characterised particularly by an improved solids content and
improved resistance to acid at elevated temperatures. As
compared with GB-A-2 254 328 the coating agents according to
the invention likewise have an improved solids content, with
improved gloss and improved resistance to acid. According to
the invention, the gloss, pendulum hardness and resistance to
acid are also improved compared with JP-A-158 079. By
comparison with DE-A-42 04 518 the invention provides
considerably improved resistance to acid. -
"';';'` '~ ',.''''',.
:;~;' ,,
'-.' . . ~,:
.. .. .~.. -
2 1 3 ~
21
.~
Example of manufacture Pl~
,: ~
Reaction of isophorone diisocyanate-isocyanurate with diethyl malonate
:.. - ~, ,~,:
376 (P = parts by weight) of isophorone diisocyanate-isocyanurate : ~
(obtainable from Huls under the trade name ~estanat IPDI T-1890) are -. .
dissolved in 350 P of Solvesso lO0 with heating to 80 C.
Subsequently, 4 P of water-free lithium hydroxide are
added. Then 271 P of diethyl malonate are added dropwise
in such a way that the reaction temperature does not exceed
90 C. The reaction mixture is kept at 90 C until an NCO
content of c0.5~ is reached. The undissolved lithium
hydroxide is filtered by filtration ove- G 1 ~m filter.
. .. ~
Final values: solids (1 h/150 C): 60 /, visccsi-y ~ ~
(25 C): 2400 mPas, colour number (C-a-~-.e-): 2; l thium'~'''''i~,~,f
content (atomic absorption spectroscopy): ~8 p_m ~ ~
~- :. ,-, :.
Example of manufacture Pl-2
Reaction of hexamethylene diisocyanate-isocyanurate wlth
diethyl malonate -~
In the same way as e~cample 1), 351 ~ of ~e:camethylen~
diisocyanate-isocyanurate (obtainaDl- f-_~ R~.c-.--~^ulenc
under the trade name Tolonat HDT/100) G-e _eac~ed wi.h
... ,.., ~ ~ .
' '~ ',~
- .. . ~...
... ~ .. ..;
,. ,. ~ . . :.
``````` '`.~
,": ~
1 3~ 2
~2 :~
~ ~ ''~.','.`
295 P of diethyl malonate in 350 P of Solvesso 100 in the :
presence of .3 P of water-free lithium hydroxide. ~-~
Final values: solids (1 h/150 C): 60.3~; viscosity ; ~,' !~'
(25 C): 680 mPas; colour number (Gardner): 1. '1'i~''"'''.,"~
Example of manufacture P1-3
Reaction of isophorone diisocyanate-isocyanurate with ethyl ~ a
10 acetoacetate
In the same way as exam~le 1), alo P of Vestanat I~DI ;;~
T-1890 are reacted with 240 P of ethyl acetcacetat~ ir.
350 P of Solvesso 100 in the presence of ~.1 F of wate~
15 free lithium hydroxide. "~
Final values: solids (1 h/150 C): 61~; vis~~sitv
(25 C): 1300 mDas; colcur numbe_ (G~rc-~
If the polyisocyanates of Example of manufacture Pl-1, Pl-2 and
Pl-3 are used as component D), the obtained coatings are particularly .. `
free of yellowings. :
`~ ~
