Note: Descriptions are shown in the official language in which they were submitted.
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
Organic based varnish or gelcoat, methods for its manufacture and use, and
substrate
comprising such varnish or gelcoat.
The present invention relates to an organic based lacquer/ varnish or coating
in the form of
organic based gel coatings as defined by the preamble of claims 1 and 8. The
present
invention further relates to the manufacture of lacquer/ varnish or coatings
as defined by the
preamble of claims 9, 10, 11 and 17 respectively. Still further the present
invention relates to
utilization of such organic based lacquer/ varnish or such coating as a
protective coating on
surfaces of aluminium or steel, particularly of rolled aluminium. Finally the
present
invention relates to a substrate comprising a coating of above mentioned type.
(In the
following we will generally - of practical reasons - refer to lacquers/
varnishes as lacquers
only).
Background
It is previously known to manufacture coatings in the form of lacquers that in
dried form are
purely organic and which have the advantage or the characteristic over
lacquers with an
inorganic content, that they as clear lacquers may be manufactured with
significantly more
glossy surfaces. It is however a disadvantage with these lacquers and coatings
that their wear
2o resistance are not particularly good, due to their inability to include
conventional fillers that
would change their appearance.
From SE patent application No. 9603174-5 (KompoPigment Ltd.) presents the
manufacture
of aqueous paintings and lacquers with a content of polymers, in which to
improve the wear
resistance of the painting or the lacquer, particles of Si02 are added, which
particles have a
size up to 150 nm, preferably no more than 100 nm, in a weight content of
maximum 65% of
the dry weight of the dispersion.
EP A1 0 555 052 describes a fluid mixture comprising an acryl monomer, silica
particles and
at least one initiator for ultraviolet curing of said mixture, as well as a
component to inhibit
decomposition of the mixture caused by the ultraviolet radiation. The silica
particles of said
mixture are typically of a size 15-30 nm. The object of said mixture is the
manufacture of
transparent, organic based coatings that are wear and weather resistant. The
patent is limited
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
in its scope to one organic system, namely acryl, which in its basis is a
mixture of a monomer
with silica particles, not an organic resin.
From a.o. EP 0 786 499 is known the fact that wear resistant coatings may be
formed from a
composition consisting of multifunctional organo-metallic components
(designated A) that is
combined with an organic monomer which includes several ftinctional groups
(designated B).
For this known method it has been shown that a strong binding is formed
between the
organo-metallic components and the organic monomer prior to polymerization)
hardening,
cfr. page 4, line 29-30. The subsequent polymerization yields a network
comprising a
i0 combination of the A and B components in which the inorganic components are
chemically
bound to organic polymerized structure in a single common network.
From DE 199 24 644 is known a method for the manufacture of a lacquer
comprising nano
particles. The method comprises in-situ formation of the particles through
hydrolysis and
condensation of metal oxides, so-called sol-gel synthesis. The objective with
performing the
manufacture in-situ as suggested, is to control the particle size so that
agglomeration does not
lead to larger particles than desired. This publication too concentrates on
systems leading to
a single, common network of matrix and nano-particles, cfr. e.g. column 2,
line 63-66.
2o It is worth noticing that aqueous paintings and lacquers are dispersions of
the relevant
polymer, which after removal of the solvent (actually dispersion agent) builds
a protective
layer. This means that the polymer is not present in the form of an actual
solution. When the
water evaporates and the polymer settles on a surface, the many minor polymer
particles
"float together" and builds a continuous, protective coating. Even if this
takes place in a
degree that is good enough for many purposes, aqueous paintings and lacquers
still provide a
lot weaker protection than organic based lacquers and solvents, where the
polymer prior to
application is completely dissolved, and during the hardening builds a
continuous protective
layer with a basis in the single molecules of the polymer.
Due to the above mentioned chemical difference between aqueous and organic
based lacquers
and paintings, it is not possible just to apply a method like the one
described in said Swedish
patent to lacquers based on organic solvents.
It is known to add inorganic particles of a size of several micrometers (p,m)
to aqueous or
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
organic based lacquer systems (so-called fillers or pigments). This
modification may affect
the wear resistance properties somewhat, but is rather used to change the
appearance (like the
colour) or to increase the weight of the lacquer. The object of the present
invention is to
modify the wear resistivity of clear lacquer systems without changing other
properties like
brightness and glossiness.
0b j ective
It is an object with the present invention to provide a lacquer/ gel-coat and
coating
respectively, and a method for the manufacture of such a lacquer/ gel-coat,
obtainable as a
to glossy clear lacquer or a glossy gelcoat surface with significantly
improved wear resistance
compared to known glossy lacquers / coatings of this type.
It is a further object to provide a coating in the form of a lacquer/gel-coat
with properties that
contributes to the corrosion resistance of the surfaces to be protected,
hereunder avoiding that
the protective layer becomes so brittle that it easily cracks and allows the
entrance of
humidity.
It is a further object to provide a protective layer that to a certain extent
will contribute to
flame retardancy.
It is a still further object to provide a lacquer and a coating respectively
that is suited to
provide rolled surfaces of aluminium and/ or steel a protective layer that is
hard, wear
resistant, weather resistant, smooth, glossy and clear.
Finally it is an object to provide a method of modifying known, commercial
lacquers based
on organic solvents, in such a way that the above mentioned objects is
obtained.
The invention
The invention more precisely consists of a lacquer or a gel-coat of the kind
mentioned
initially, which is characterized by the features defined by the
characterizing part of claim 1.
Further and preferred embodiments of the lacquer or the gel-coat according to
the invention,
are defined by the claims 2-7. The invention further relates to a finished
hardened coating as
defined by claim 8.
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
The invention further concerns alternative embodiments of a method for the
manufacture of
such a lacquer or such a gel-coat as mentioned initially, which embodiments
are characterized
by the features defined by the characterizing parts of claims 9, 10, 11 and 17
respectively.
Preferred embodiments of the method according to the invention are defined by
the claims
12-16.
The invention still further concerns a utilization of such a lacquer or such a
gel-coat as
defined by the characterizing part of claim 1 S. Preferred embodiments of the
utilization
to according to the invention, are defined by the claims 19-21. Finally the
invention relates to
substrate comprising a coating of the mentioned type.
The core of the invention may be expressed as providing the kind of lacquer or
coating that
the invention relates to with inorganic polymer particles of nano size, i.e.
with a particle size
mainly in the area 1-100 nm. Such particles cannot just be "added" in the form
of particles as
such, their provision need to take place through one or more of the
alternative methods by
which the particles are formed through chemical reactions taking place in situ
or immediately
prior to their addition to the base component of the lacquer. The three
alternative
embodiments of the method according to the invention, defined by the claims 9,
10 and 11
2o respectively, are in the following also designated as model 1, model 2 and
model 3
respectively. It is however, also possible to combine the three methods as
defined by claim
17.
An important aspect is that particles of the relevant type and size are not
present as discrete
particles in a lacquer matrix. The particles will rather form their own
inorganic/ organic
network that comes in addition to the organic network of the lacquer. These
two networks
will be present side by side independent of each other, but they may to a
larger or lesser
degree be attached to each other through cross-linked bondings. The degree of
network
formation is to some extent dependent also by which of the three manufacturing
model that is
chosen and by the particle size, and cannot be predicted entirely on a
theoretical basis. The
invention is not, however, limited to certain degrees of network formation or
to any certain
mechanism for the formation of such networks. When in the following reference
is made to
the "particles" in the lacquer, this also is meant to include the presence of
such an additional
network in the finished hardened lacquer or the finished hardened coating.
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
Already while the lacquer/ gel-coat is present in its fresh form, it will
comprise varying
degrees of the two networks discussed, but the degree of cross-linking in
three dimensions
will be significantly lower than in the finished, hardened coating.
The practical implication of two principally independent networks is a.o. that
the coating
formed not only is strong, but in addition is more flexible than many other
lacquers/ coatings,
included such where the nano-particles are tied into a network with the
lacquer's organic
resin. Coatings that are less flexible will soon experience crack formation if
put on top of
materials that themselves are flexible/ movable. Rolled aluminium or steel
which are wound
to on to big coils are typical examples of utilizations where it is vital that
the finished hardened
lacquer is flexible if it shall be able to provide a lasting protection to the
metal.
According to a first embodiment of the method according to the invention,
hereinafter
designated model 1, a first particle dispersion (sol) is prepared by partial
hydrolysis of one or
more monomer compounds of the kind previously stated. A solvent compatible
with the
solvent of the lacquer to be modified is used for this purpose. Thereafter the
mentioned sol is
added to the lacquer, and at this stage the sol includes nano-particles of
desired size. It is
preferred also to modify the surface of the particles through a treatment that
may comprise
adsorption of polymers, reactions with a silane, a zirconate, a
zircoaluminate, an orthotitanate,
2o an aluminate or a combination of such treatments.
Chemically there are two steps in the preparation of a sol from metal-organic
compounds
according to some of the embodiments , model 1 and 2, of the invention. A
solution
containing monomer compounds of the formula M(OR)" or R'-M(OR)" is used as a
starting
solution. In the formula M(OR)" , M is a metal ion and R is an organic group
chosen among
alkyl, alkenyl, aryl or combinations of these with from 1 to 8 carbon atoms.
In the formula
R'-M(OR)", R' = R or R' =R-X, where X is an organic group like e.g. amine,
carboxyl or
isocyanate. It is preferred that R is a simple alkyl with 1-4 carbon atoms.
The index is an
integer from 1 to 6 dependent upon the valency of the metal ion.
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
The first step is hydrolysis of the metal alkoxidea where alkoxide ligands are
replaced by
hydroxyl groups:
M-OR + H-OH -~ M-OH + ROH
The second step is condensation, where hydroxyl groups either may react with
hydroxyl or
alkoxy groups from other metal centres, forming M-O-M bonds and either water
or alcohol.
M-OH + HO-M= ~ ---M-O-M---- + H20
1o
or
M-OR + HO-M---- -~ ---M-O-M= + ROH
15 The course of reaction is principally the same if started from the compound
R'-M(OR)", as
the group R' does not participate in the hydrolysis or condensation reactions.
The resulting solution consists of inorganic polymer particles dispersed in a
solvent.
2o A preferred variant includes the addition of a compound with functional OH-
groups, like e.g.
butyldiglycol or ethylhexanol during the hydrolysis/ condensation step. This
has shown the
formation of a stable sol that is compatible with lacquers/ gel-coats.
E.g. when an acrylic lacquer is to be modified, it is preferred to add
butyldiglycol (BDG)
25 during the hydrolysis/ condensation of ~r-aminopropyltriethoxysilane (fir-
APS). A BDG-
molecule will be able to substitute an ethoxy-group of y-APS (-ODGB). -ODGB is
probably
significantly more difficult to substitute by -OH compared to the case of -OEt
due to
possible interactions between the -ODGB substituent and the Si-atom. Such
interactions are
not significant between OEt and the Si atom. Generally it is to be expected
that larger alcohol
30 residues are more difficult to substitute by -OH due to the fact that a
larger alcohol molecule
subsequent to a possible hydrolysis remains for a longer period of time in the
vicinity of the
silane than a smaller alcohol molecule does. As a consequence the opposite
reaction
(condensation between ---Si-OH and EtOH to ---SiOR + HZO) is more likely for
larger alcohol
molecules than for smaller. It is decisive for the particle formation that
only two sites on the
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
Si-atom are available for hydrolysis/ condensation. Three or four sites with
possibility of
hydrolysis/ condensation usually leads to formation of large agglomerates
which are normally
difficultly soluble in organic solvents. As an alternative to the
intramolecular catalysed
hydrolysis/ condensation, an intermolecular variant is also possible. In this
case the amino
group of a silane molecule in the vicinity of another silane molecule
catalyses the hydrolysis)
condensation of the latter silane molecule. This way nano-particles compatible
with the
acrylic lacquer are formed.
By a variant of the method according to the invention, model 2, a controlled
amount of
1o inorganic compounds of the mentioned type is added to an existing
commercial clear lacquer
or an existing commercial gel-coat. To obtain in-situ formation of particles
within the desired
size it is necessary to establish chemical conditions ensuring a correct
balance between the
kinetics of the two required reactions, namely the condensation reaction and
the hydrolysis.
While the condensation reaction provides for the formation of polymer chains
(polymerizes)
from monomer (single) molecules, the hydrolysis provides for a polycrystalline
precipitation
or oxohydroxide precipitation taking place in contact with the components of
the lacquer. A
suitable choice of inorganic compound combined with exchange (replacement) of
alkoxide
groups with strong ligands, will slow down the hydrolysis reactions compared
to
condensation reactions, which will ensure that said chains do not become too
long, but swill
2o stay within a range herein denoted as oligomers. In practice this means
that the particles will
often be only of a few nm in size, most typically smaller than 10 nm. It is
preferred that the
particles are smaller than 30 nm, as that ensures that the lacquer remains
bright. In the same
manner as for model 1 it is preferred additionally to modify the surface of
the particles
through a treatment that may comprise adsorption of polymer, reaction with a
silane, a
zirconate, a zircoaluminate, an orthotitane, an aluminate, or a combination of
such treatments.
According to a third variant of the method according to the invention, model
3, a powder of
agglomerated particles of the above mentioned type is first established. The
agglomerates of
the powder are so loose that they may be broken down to particles of nano size
with a
3o mechanical treatment, a chemical treatment or a combination of such
treatments. This implies
that clay based materials represent an alternative that may be used for model
3. In the same
manner as for model 1 it is preferred additionally to modify the surface of
the particles
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
through a treatment that may comprise adsorption of polymer, reaction with a
silane, a
zirconate, a zircoaluminate, an orthotitane, an aluminate, or a combination of
such treatments.
Common for the three mentioned embodiments/ variants is that it is possible to
start from
existing lacquers, preferably glossy clear lacquers based on organic solvents,
and to change
their properties by means of a treatment with inorganic polymer particles, so
that the resulting
lacquer incorporates particles of nano size. These particles will as mentioned
form a three-
dimensional network that comes in addition to the organic network of the
lacquer itself, and
contributes to providing the lacquer an unsurpassed wear resistance compared
to ordinary
organic based lacquers, while the finished hardened lacquer still is maintains
its flexibility
and does not become brittle. The additional network comprising the inorganic
particles is
principally independent of, but may be partly bonded to, the organic network
of the lacquer.
With addition of a coht~olled amount of inorganic polymer particles is meant
an amount that
is sufficient to allow the particles to form such a network as described
above. The amount
required will have to be determined in each sepaxate case in dependence of
particle size,
particle type and type of lacquer. In general the amounts of inorganic
particles will stay
between an interval of from 0.5 to 50 % by weight calculated on a basis of the
laquer in
question. At concentrations close to or below the lower of said limits the
particles will only
2o to a limited degree be able to form the network necessary to obtain the
desired improvement
of the lacquer's properties. At concentrations above said upper limit there is
a risk that the
particles will negatively affect the lacquer's appearance, so that it will no
longer appear as
glossy, smooth and clear as prior to the particle addition.
The metal ion M according to the invention is chosen among a series of metals,
such as
zirconium, aluminium, titanium, silicon, magnesium, chrome, manganese, iron,
cobalt and
several others. Through research it has been found that compounds where the
metal ion is
zirconium, aluminium, titanium, silicon or a combination of these are very
well suited for the
purpose, and these metals therefore constitute preferred embodiments of the
metal ion
according to the invention. The organic part R of the molecule is an alkyl, an
alkenyl, an aryl
or a combination of these groups, of practical reasons limited in size to
groups comprising a
maximum of 8 carbon atoms. It is however preferred that R does not have more
than 4
carbon atoms, and more preferred that it is a simple alkyl like methyl, ethyl,
propyl or butyl.
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
While the normal thing will be that one of the three distinct methods for
modifying a base
lacquer/ gel-coat is chosen for a given application, it is also possible to
combine two of the
methods or all three methods (or elements of these methods) as defined by
claim 17.
Generally coatings with a thickness between 1 and 50 p,m are made, depending
on the coating
method and the properties of the substrate. Due to the improved properties of
the coating
made according to the invention, such as high wear resistance, the coating
thickness may be
lower, e.g. in the range 1 to 10 Vim.
l0 Many different organic types of lacquers are suited for the purpose of the
invention, and the
type is largely decided by the area of use. To mention the most important
ones, acrylic
lacquers, epoxy lacquers, polyester lacquers, polyurethane lacquers, polyamide
lacquers and
polycarbonate lacquers, may all be used as a the basis lacquer according to
the invention.
While a lacquer is applied to and adhere to a surface that is to be protected,
a gel-coat is used
e.g. to manufacture products like car top-boxes, plastic boats, plastic
containers/ tanks or body
works, which may all include reinforcements in the form of glass fibres or the
like. The
processing steps are thus significantly different from applying a laquer even
though the
chemical principles of their outer layer are quite similar. When a product is
gel-coated, a
2o model with a shape complementary to the desired product is first formed in
a material to
which the gel-coat will not adhere with any significant strength. The gel-coat
is thereafter
applied to the model by means of conventional techniques, and thereafter
provided with any
desired reinforcements, normally followed by another layer of gel-coat. The
first applied
layer of gel-coat constitutes the outer layer of the product, and has in this
connection the same
function as the lacquer, namely to form an attractive and strong surface, also
providing UV-
protection so that the material does not decompose under the top layer.
Below the invention is further elaborated through a number of test examples
for some of the
manufacturing methods according to the invention. It is not exemplified
utilizations of steel
3o surfaces, but it should be emphasized that they in principle is similar to
the examples shown
for aluminium, though the adhering properties and hardness are somewhat
different for these
materials.
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
A commercial clear polyurethane lacquer (DD lacquer from Scanox, Norway) was
modified
according to model 2, and applied to a parquet (floor).
5 The polyurethane lacquer is a two component lacquer where one component is
the resin
(component A) and the other component is a hardener (component B).
Modification: 10 ml tetramathoxy-orthosilane (TMOS) from Sigma Aldrich, CH was
added
drop by drop with an interval of about 5 seconds between each drop, to 40 ml
of component A
10 under vigorous agitation (800 rpm). The entire process lasted about 40 min.
20 ml of
component B was added to the solution under agitation.
Applying : After 5 minutes of agitation the lacquer was applied to two borads
of parquet with
a brush. The boards each had two areas, one of which received two layers of
the modified
lacquer while the other area received two layers of non-modified lacquer.
Testing: After 24 hours the lacquer was completely hardened. The thickness was
measured
to about 20 ,um and the wear resistance was tested by means of a Universal
Weax Testing
Machine from Eyre/ Biceri. One of the lacquered boards was strapped to the
machine that
2o comprised a steel knife. The movable part was placed on the board with a
constant weight
and the apparatus was started. The number of turns were automatically counted.
After 80
turns the surface was observed. On the part covered with non-modified lacquer
almost all the
lacquer was worn off. On the part covered with modified lacquer, the lacquer
was worn very
moderately.
The other board was exposed to a burning flame for at least 20 seconds and
thereafter
observed. The part covered with modified lacquer had turned white due to
formation of a thin
oxide layer that served to inhibit the flames. The part covered with the non-
modified lacquer
was completely black and had started burning immediately after contact with
the flames.
~xample 2
A commercial clear epoxy lacquer VS 150 from Valspax, USA was modified
according to
model 2 and used for coating of aluminium sheets. The eopxy lacquer was a one
component
lacquer comprising both the resin and a cross-linker.
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
11
Modification: 20 ml of a mixture of 61 g tetraethoxy-orthosilane (TEOS) from
Sigma
Aldrich, CH, 200 g butanol and 121 g aluminium sec-butoxide from Sigma
Aldrich, CH was
added dropwise with about 2 second intervals between each drop to 40 ml of
lacquer under
vigorous agitation (800 rpm). The entire process lasted about 40 minutes.
Applying: After 5 minutes of agitation the lacquer was applied to an aluminium
sheet by "bar
coating" (rod number 26). Immediately after application the sheet was placed
in a convection
oven holding the temperature of the aluminium sheet ("Peak Metal Temperature"
PMT) at
250 °C. The sheet was thereafter removed from the oven and cooled in
cold water. The
1o coated layer was measured to 8 ,um.
Testing: The wear resistance properties were tested by means of a hardness pen
of type
Erichsen, Germany. The method consists of making a scratch with the hardness
pen. The
force applied being controlled by a spring. The hardness value correlated to
the force is read
15 from the pen. Parallel readings showed that the force on the sheet covered
by the modified
lacquer was beyond 1 N, while the force on the sheet covered by the non-
modified lacquer
was below 0.2 N.
20 A commercial clear acrylic lacquer (SZ-006 from Rhenania, Germany) was
modified
according to model 2 and used for coating aluminium sheets.
The acrylic lacquer was a one-component lacquer containing both resin and
cross-linkers.
25 Modification: 4.7 g of tetra isopropyl orthotitane from Sigma Aldrich, CH
was added to 12.9
g methacrylic acid under agitation. After 15 minutes of agitation the solution
was added to
26.4 g lacquer under agitation.
Application: After 5 minutes of agitation the lacquer was applied to an
aluminium sheet
3o using "bar coating" (rod No. 26). Immediately thereafter the sheet was
placed in a convection
oven, holding the temperature of the aluminium sheet ("Peak Metal Temperature"
PMT) at
241 °C. The sheet was thereafter removed from the oven and cooled in
cold water. The
coated layer was measured to 8 ,um.
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
12
Testing:
Wear resistance.
The wear resistance properties were tested by means of a Universal Wear
Testing Machine
from Eyrel Biceri. One of the lacquered sheets was strapped to the apparatus.
A cotton pole
was attached to the movable part and placed on the lacquered sheet with a
constant weight of
588 g (3x load) and the apparatus was started. The number of turns was
automatically
counted. After 20 turns the surface of the sheet was metallized and observed.
The number of
die lines on the part coated with non-modified lacquer was comparatively
large. On the part
coated with modified lacquer the die lines wexe barely visible. On an empiric
scale from 1 to
6 where 1 is best (no die lines) and 6 worst (many die lines) the modified
lacquer got value 2
and the non-modified lacquer got value 3.
Clearness
The lacquer was optically clear. The clearness of a lacquer may be quantified
by measuring
the brightness (RD120). The brightness of the modified lacquer had a value of
1793, which
was in the magnitude of the brightness of the non-modified lacquer (1773).
Example 4
The same commercial lacquer as used for example 3 was modified according to
model 1 and
2o used for coating aluminium sheets.
Modification: 11.34 g of an alcoholate solution of titanium propoxide from
Sigma Aldrich,
CH was added to 7.74 hexanoic acid under agitation. Thereafter 1 g of
distilled water was
added under agitation. After 15 minutes of agitation, 10 g of the resulting
sol was added to
0.165 g y-aminopropyl triethoxysilane under agitation. 1 g of the resulting
mixture was
thereafter added to 10 g lacquer under agitation.
Application: After 5 minutes of agitation the lacquer was applied to an
aluminium sheet by
"bar coating" (rod NO. 26). Lmmediately thereafter the sheet was placed in a
convection
oven, holding the temperature of the aluminitum sheet ("Peak Metal
Temperature" PMT) at
241 °C. The sheet was thereafter removed from the oven and cooled in
cold water. The
coated layer was measured to 8 ,um.
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
13
Characterizing and testing
Sol particle size
The sol particle size was determined by means of the light scattering
principle. A commercial
instrument, "Zetasizer 3" from Malvern, UK, was used to determine the size
distribution. The
size distribution was sharp and the average particle size was 5 nm.
Wear resistance properties
The wear resistance properties were tested by means of a Universal Wear
Testing Machine
from Eyre/ Biceri, as for example 3. The constant weight was 5~~ g (3x load).
The number
to of die lines on the part coated with non-modified lacquer was comparatively
large. On the
part coated with modified lacquer the die lines were barely visible. On an
empiric scale from
1 to 6 where 1 is best (no die lines) and 6 worst (many die lines) the
modified lacquer got
value 2 and the non-modified lacquer got value 3.
Clearness.
The lacquer was optically clear. The clearness of a lacquer may be quantified
by measuring
diffuse transmission. This may be performed e.g. by using a clear glass plate
as a substrate
for the lacquer. First the diffuse transmission is measured on the glass plate
alone. Thereafter
the lacquer is applied to the glass plate and the diffuse transmission is
measured again. The
change in diffuse transmission after the application of the lacquer is a good
measure of the
clearness of the lacquer (provided that the interface between lacquer and the
glass plate does
not contribute significantly to the light scattering). The measurements was
done with an
apparatus according to the DIN 5036 standard.
Diffuse transmission of the clear glass plate was measured to 0.5%. The non-
modified
lacquer was applied to the glass plate (coating layer of 5 Vim). The diffuse
transmission was
thereafter measured to 1.5%. Diffuse transmission for the modified lacquer was
measured
below 6%.
F~~1
The commercial lacquer used for example 3 was modified according to model 1
and applied
to aluminium sheets.
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
14
Modification: 4.7 g of tetra isopropyl orthotitane from Sigma Aldrich, CH was
added to 15.3
g pentanoic (valeric) acid under agitation. Thereafter 0.45 g of distilled
water was added
under agitation. After 15 minutes agitation of this sol, 10 g sol was added to
10 g lacquer
under agitation.
Application: After 5 minutes of agitation the lacquer was applied to an
aluminium sheet by
"bar coating" (rod NO. 26). Immediately thereafter the sheet was placed in a
convection
oven, holding the temperature of the aluminium sheet ("Peak Metal Temperature"
PMT) at
241 ° C. The sheet was thereafter removed from the oven and cooled in
cold water. The
1o coated layer was measured to 8 ,um.
Characterizing and testing
Sol particle size
The sol particle size was measured by means of "Zetasizer 3" from Malvern, UK.
The size
distribution was sharp and the average particle size was 3 nm.
Wear resistance properties.
The wear resistance properties were tested by means of a Universal Wear
Testing Machine
from Eyre/ Biceri, as for example 3. The constant weight was 980 g (5x load).
The number
of die lines on the part coated with non-modified lacquer was comparatively
large. On the
part coated with modified lacquer the die lines were barely visible. On an
empiric scale from
1 to 6 where 1 is best (no die lines) and 6 worst (many die lines) the
modified lacquer got
value 3 and the non-modified lacquer got value 6.
Clearness
The lacquer was optically clear. The clearness of a lacquer may be quantified
by measuring
the brightness (1tD/20). The brightness of the modified lacquer had a value of
1693, which
was comparable to the brightness of the non-modified lacquer (1773).
Example 6
The same commercial lacquer as used for example 3 was modified according to
model 3 and
applied to aluminium sheets.
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
Modification: 10 g of a commercial titanium oxide from Nanophase, USA,
comprising titania
particles with an average size of 20 nm (20 % by weight in an organic solvent)
was added to
10 g lacquer under agitation.
5 Application: After 5 minutes of agitation the lacquer was applied to an
aluminium sheet by
"bar coating" (rod NO. 26). Immediately thereafter the sheet was placed in a
convection
oven, holding the temperature of the aluminium sheet ("Peak Metal Temperature"
PMT) at
241 °C. The sheet was thereafter removed from the oven and cooled in
cold water. The
coated layer was measured to 8 ,um.
Testing: The wear resistance properties were tested using a "taber abraser"
like for example
3. The weight loss measured for the sheet coated with the non-modified lacquer
was
significantly larger than the weight loss of the sheet coated with the modif
ed lacquer.
E~ple 7
A commercial clear gel-coat was modified according to model 1 and used for
providing a
protective layer on a glass reinforced polyester plate.
Modification: A zirconia sol adapted to styrene was manufactured by mixing 40
ml of a
2o Zr(OPr)4 solution from Sigma Aldrich, CH with 29.6 ml methacrylic acid
under agitation.
When the composition had reached room temperature 3.72 ml water was slowly
added under
agitation. Thereafter 40 ml of styrene was added. Unsaturated polyester was
added to the
composition to yield a 70% polyester. After the addition of peroxide the
composition was
applied to a mould with a brush and reinforced with polyester/ glass.
Testing: The wear resistance properties were tested with a hardness pen from
Erichsen,
Germany. No scratches (die lines) was observed. When the same force ( 1 N) was
applied to
a non-modified gel-coat, a lot of die-lines were observed.
3o Ex~nzple 8
A commercial clear epoxy lacquer was modified according to model 3 and applied
to
aluminum sheets.
The epoxy lacquer was a one-component lacquer comprising both the resin and
the cross-
linker.
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
16
Modification: 9 g of a commercial bohemite powder from Condea Chemi was added
to 20 g
butanol under agitation. Thereafter 2.14 g of methacrylic acid was added under
agitation.
After 15 minutes of agitation the resulting sol was subjected to an ultrasound
treatment (300
W 5min., 50% pulse), and the sol was added to 10 g of lacquer under agitation.
Application: After 5 minutes of agitation the lacquer was applied to an
aluminium sheet by
"bar coating". Immediately thereafter the sheet was placed in a convection
oven, holding the
PMT at 250 °C. The sheet was thereafter removed from the oven and
cooled in cold water.
1o Testing: The wear resistance properties were tested using a "taber abraser"
like in example 3,
the sheet being weighed before and after the test.. The weight loss measured
for the sheet
coated with the non-modified lacquer was significantly larger than the weight
loss of the sheet
coated with the modified lacquer.
15 Firample 9
The same commercial lacquer as used for example 3 was modified according to
model 3 and
applied to aluminium sheets.
Modification: 3 g of a commercial titanium oxide powder from Tioxide, England
was added
2o to 6 g of butyldiglycol (BDG) and 8.33 g of 1-methoxy-1-acetoxypropane. The
resulting
dispersion was thereafter subjected to an ultrasound treatment for 17 minutes
(200 W, 50%
cycle). Thereafter the components of the lacquer was added in the following
sequence and
under agitation: 0.0072 g of PTSA solution, 7.2 g of HMMM Melamine resin
solution, 9 g of
blocked HDI isocyanate resin-solution and 29.4 g of acrylic resin solution.
Application: After 5 minutes of agitation the lacquer was applied to an
aluminium sheet by
"bar coating" (rod NO. 26). Immediately thereafter the sheet was placed in a
convection
oven, holding the temperature of the aluminium sheet ("Peak Metal Temperature"
PMT) at
241 °C. The sheet was thereafter removed from the oven and cooled in
cold water. The
3o coated layer was measured to 12 ,um.
Testing
Wear resistance properties.
The wear resistance properties were tested by means of a Universal Wear
Testing Machine
from Eyrel Biceri, as in example 3. The constant weight was 588 g (3x load).
The number of
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
17
die lines on the part coated with non-modified lacquer was comparatively
large. On the part
coated with modified lacquer the die lines were barely visible. On an empiric
scale from 1 to
6 where 1 is best (no die lines) and 6 worst (many die lines) the modified
lacquer got value 1
and the non-modified lacquer got value 3.
Clearness
The lacquer was optically clear. The clearness of a lacquer may be quantified
by measuring
the brightness (RD/20). The brightness of the modified lacquer had a value of
1727, which
was comparable to the brightness of the non-modified lacquer (1693)
i0
The same commercial lacquer as used for example 3 was modified according to
model 1 and
applied to aluminium sheets.
Modification: 60 g of y-aminopropyltriethoxysilane (~-APS) was added to 13.2 g
of BDG
and 15.18 g of distilled water. The sol was agitated moderately for 12 hours.
5 g of the sol
was then added to 1 g of lacquer under moderate agitation.
Application: After 5 minutes of agitation the lacquer was applied to an
aluminium sheet by
"bar coating" (rod NO. 26). Tmmediately thereafter the sheet was placed in a
convection
oven, holding the temperature of the aluminium sheet ("Peak Metal Temperature"
PMT) at
241 °C. The sheet was thereafter removed from the oven and cooled in
cold water. The
coated layer was measured to a thickness of 7 ,um.
Testing
Wear resistance properties
The wear resistance properties were measured by means of a "taber abraser"
according to ISO
standard D 4060-95. The method comprises exposing the lacquered surface to
wear by
means of a rubber wheel rotating on the sample. The number of turns is
automatically
registered (1000 turns), and the force is determined by a known weight (500
g). The sheets
are weighed before and after the test. The weight loss of the sheet coated
with non-modified
lacquer was 12.37 mg, while the weight loss of the sheet coated with the
modified lacquer
was 1.22 mg.
The wear resistance properties were also tested by means of a Universal Wear
Testing
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
18
Machine from Eyre/ Biceri, as in example 3. The constant weight was 980 g (5x
load). The
number of die lines on the part coated with non-modified lacquer was
comparatively large.
On the part coated with modified lacquer the die lines were barely visible. On
an empiric
scale from 1 to 6 where 1 is best (no die lines) and 6 worst (many die lines)
the modified
lacquer got value 1 and the non-modified lacquer got value 6.
Example 11
The same commercial lacquer as used for example 3 was modified according to
model 1 and
applied to aluminium sheets.
Modification: 100 g of a commercial silica sol from Nissan Chemicals, Japan,
was added to
22.4g ~-APS under slow agitation for 15 minutes. 10.2 g of the modified sol
was thereafter
added to a mixture of 3.3 g of 'y-APS and 1.5 g of BDG under slow agitation.
5.1 g of the
resulting composition was added to 1 g of lacquer under slow agitation.
Application: After 5 minutes of agitation the lacquer was applied to an
aluminium sheet by
"bar coating" (rod No. 26). Immediately thereafter the sheet was placed in a
convection oven,
holding the temperature of the aluminium sheet ("Peak Metal Temperature" PMT)
at 241 ° C.
The sheet was thereafter removed from the oven and cooled in cold water. The
coated layer
2o was measured to a thickness of 7 ,um.
Testing
Wear resistance properties.
The wear resistance properties were tested by means of a Universal Wear
Testing Machine
from Eyre/ Biceri, as in example 3. The constant weight was 588 g (3x load).
The number of
die lines on the part coated with non-modified lacquer was comparatively
large. On the part
coated with modified lacquer the die lines were barely visible. On an empiric
scale from 1 to
6 where 1 is best (no die lines) and 6 worst (many die lines) the modified
lacquer got value 1
and the non-modified lacquer got value 3.
The tables below summarizes the types of lacquers/ varnishes used and the
results of the
various hardness tests and brightness tests.
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
19
Table 1. Characterization of various types of lacquers prior to and after
their modiftcation
according to model No. 1.
Ex. Type Model Type of Scratch test Taber abraserBright-
No. of No. modification(1=best, 6=worst)Weight lossness
lacquer 3X load see m
text
4 Ac lic Non-mod~ed 3
4 Ac lic 1 Ti 2
5 Ac lic Non-modified6 * 1773
5 Ac lic 1 Ti 3 * 1693
7 E ox Non-modified**
107 E ox 1 Ti +~~
Ac lic Non-modified6 * 1
2.37
10 Ac lic 1 Si 1 * _
1.22
11 Ac lic Non-modiEed3
11 Acrylic 1 Si I1 I I I
SX load (see text)
** see text
Table 2. Characterization of various types of lacquers prior to and after
their modification
according to model No. 2.
Ex. Type Model Type of Scratch test Hardness Bright-
No. of No. modification1=best, 6=worstpen ness
lac uer N
1 PU Non-modified**
1 PU 2 Si _ + ** _ _ _
2 E ox Non-modified 0.2
2 E ox 2 Si/Al > 1
3 Ac lic Non-modified3 1793
3_ Acrylic I 2 Ti ~ I I 1773
__
_
** see text
Table 3. Characterization of various types of lacquers prior to and after
their modiftcation
according to model No. 3.
Ex. Type Model Type of Scratch Taber abraserBright-
No. of No. modificationtest Weight lossness
lacquer (1=best,
6=worst
356 Gel-coat Non-modified **
6 Gel-coat3 Zr + **
8 Ac lic Non-modified **
8 Ac lic 3 A1 + **
9 Ac lic Non-modified3 1693
409 I-Acrylic3 I Ti I 1 I I 1727
I I
** see text
The results from the various tests show that lacquer systems with a high wear
resistance are
achieved through the modification according to (any one of) the three
embodiments of the
45 method according to the invention, while the brightness of the lacquer is
maintained.
It is emphasized that the present invention largely is related to modification
of existing,
commercial lacquers/ varnishes or gel-coats, but is not exclusively limited to
such products.
The invention is thus applicable to other lacquer/ varnishes, e.g. special
lacquers that have not
5o earlier been commercially available and new lacquers or varnishes that may
possible
constitute separate invention per se., etc.
CA 02415045 2003-O1-06
WO 02/08343 PCT/NO01/00287
Furthermore, we have for simplicity described modifications of lacquers/
varnishes or gel-
coats that are ready for use. In a commercial situation it may very well be
more convenient to
perform the modification by introducing the nano-particles as another step of
the process than
the very last one.
Still further, we have described the process in a manner in which the lacquer/
varnish each
time receives an amount of particles corresponding to a relevant field of use.
It is also
possible to add higher concentrations of particles, in which case the user
immediately prior to
application will dilute the concentrate with a standard lacquer/ varnish of
the same type to the
to desired concentration, which in addition may vary according to wear
intensity, the substrate to
which it is applied etc.
Finally, in connection with the method of manufacturing a lacquer according to
the invention,
the three alternative methods are described in a way that they may be
perceived as being
15 mutually exclusive in any practical situation, so that if model 1 is
chosen, model 2 and 3 are
automatically discarded for that particular application. This is however, not
correct, as it is
fully possible to combine the three models. For example a system may be
applied in which a
finely dispersed powder (model No. 3) is added, while simultaneously producing
other
inorganic particles from a particle dispersion according to model No. 1 or by
ih-situ formation
2o in the lacquer according to model No. 2 of the invention.
Said variations are all within the scope of the invention, as are any other
modification that a
skilled professional might introduce in order to adapt the spirit of the
invention to relevant
areas of use.
