U.S. patent application number 10/686870 was filed with the patent office on 2004-12-16 for coating composition curable with ultraviolet radiation.
Invention is credited to Kempf, Hans, Laginess, Thomas J., Stewart, Jennifer R..
Application Number | 20040254257 10/686870 |
Document ID | / |
Family ID | 33514122 |
Filed Date | 2004-12-16 |
United States Patent
Application |
20040254257 |
Kind Code |
A1 |
Laginess, Thomas J. ; et
al. |
December 16, 2004 |
Coating composition curable with ultraviolet radiation
Abstract
A UV radiation curable primer coating composition curable under
a UV radiation emitting lamp or sunlight. The coating demonstrates
improved curing time and includes ethylenically unsaturated free
radically polymerizable compounds and 0.1% photoiniator or
less.
Inventors: |
Laginess, Thomas J.;
(Temperance, MI) ; Kempf, Hans; (Swanton, OH)
; Stewart, Jennifer R.; (Dearborn, MI) |
Correspondence
Address: |
BASF CORPORATION
ANNE GERRY SABOURIN
26701 TELEGRAPH ROAD
SOUTHFIELD
MI
48034-2442
US
|
Family ID: |
33514122 |
Appl. No.: |
10/686870 |
Filed: |
October 15, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60477413 |
Jun 10, 2003 |
|
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Current U.S.
Class: |
522/64 ; 522/178;
522/33 |
Current CPC
Class: |
C09D 4/00 20130101 |
Class at
Publication: |
522/064 ;
522/033; 522/178 |
International
Class: |
C08F 002/46 |
Claims
1. A UV radiation curable primer coating composition comprising a.
5 to 50% by weight of one or more compounds containing one
ethylenically unsaturated free-radically polymerizable group per
molecule b. 5 to 50% by weight of one or more compounds containing
two or more ethylenically unsaturated free radically polymerizable
groups per molecule c. 1.0 to 60% by weight of one or more
pigments, fillers and or dyes d. 0.1 to 0.95% photoinitiators e. 0
to 20% by weight of volatile organic solvent and f. 0.1 to 10% by
weight of additives, wherein said coating is curable to a non-tacky
surface under a UVA radiation emitting lamp within 2 minutes and in
sunlight within 5 minutes.
2. A primer coating composition according to claim 1 wherein the
compound A is selected from the group consisting of 1-octene,
1-hexene, 1-decene, vinyl acetate, styrene, alpha-methylstyrene,
p-methylstyrene, esters of methacrylic acid and esters of acrylic
acid.
3. A primer coating according to claim 1 wherein compound A is
selected from butyl acrylate, t-butyl acrylate, isobornyl acrylate,
isodecyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate,
cyclohexyl acrylate and octyl acrylate.
4. A primer coating composition according to claim 1 wherein
compound B is selected from the group consisting of urethane
acrylates, diacrylates, triacrylates, polyfunctional acrylates and
mixtures thereof.
5. A primer coating according to claim 1 wherein compound B is
selected from the group consisting of hexanediol diacrylate,
tripropyleneglycol diacrylate, trimethylolpropane triacrylate,
alkoxylated trimethylolpropane triacrylate, pentaerythritol
triacrylate, pentaerythritol tetraacrylate, dipentaerythritol
hexaacrylate, urethane acrylates and unsaturated polyesters, and
mixtures thereof.
6. A primer coating according to claim 1 wherein compound B is
selected from the group consisting of di- and poly-functional
urethane acrylates.
7. A primer coating composition according to claim 1 wherein the
pigment to binder ratio is between 0.8 and 2.0.
8. A primer coating composition according to claim 1 wherein the
pigment to binder ratio is between 1.2 and 1.8.
9. A primer coating composition according to claim 1 wherein the
photoinitiator comprises a compound selected from the group
consisting of acyl phospine oxides and benziketals.
10. A primer coating composition according to claim 1 wherein said
coating is cured by 5 minute exposure to outdoor light having an
intensity of 45-65 mJoules/cm.sup.2 and demonstrates 95% post
humidity test adhesion.
11. A process for applying a primer coating composition to a
substrate comprising A. applying a UV radiation curable primer to a
substrate; B. curing the primer with a source selected from the
group consisting of one or more UV lamps having a UV-B:UV-A ratio
of 1:1 or less, and natural outdoor light having a wavelength
between 320 and 430 nm, and mixtures thereof, wherein the UV
radiation curable primer comprises a. 5 to 50% by weight of one or
more compounds containing one ethylenically unsaturated
free-radically polymerizable group per molecule, b. 5 to 50% by
weight of one or more compounds containing two or more
ethylenically unsaturated free radically polymerizable groups per
molecule, c. 1.0 to 60% by weight of one or more pigments, fillers
and or dyes, d. 0.1 to 0.95% photoinitiators, e. 0 to 20% by weight
of volatile organic solvent and f. 0.1 to 10% by weight of
additives.
12. A process according to claim 11 wherein the coating applied
comprises compound A is selected from the group consisting of
1-octene, 1-hexene, 1-decene, vinyl acetate, styrene,
alpha-methylstyrene, p-methylstyrene, esters of methacrylic acid
and esters of acrylic acid and mixtures thereof.
13. A process according to claim 11 wherein the coating applied
comprises compound A selected from butyl acrylate, t-butyl
acrylate, isobornyl acrylate, isodecyl acrylate, 2-ethylhexyl
acrylate, lauryl acrylate, cyclohexyl acrylate and octyl acrylate
and mixtures thereof.
14. A process according to claim 11 wherein the coating applied
comprises compound B selected from the group consisting of urethane
acrylates, urethane diacrylates, tri- and polyfunctional urethane
acrylates and mixtures thereof.
15. A process according to claim 11 wherein the coating applied
comprises a pigment to binder ratio between 0.8 and 2.0.
16. A process according to claim 11 wherein the coating applied
comprises a pigment to binder ratio between 1.2 and 1.8.
17. A process according to claim 11 wherein a UV light source is
applied wherein the UVA intensity is from 0.8 to 1.6
Joules/cm.sup.2, the UVB intensity is from 0.001 to 0.5
Joules/cm.sup.2 and the UVC intensity is from 0.001 to 0.3
Joules/cm.sup.2.
18. A process according to claim 11 wherein the coating is cured
under natural light conditions, said light providing an intensity
of 5-100 mJoules/cm.sup.2.
19. A process according to claim 11 wherein the substrate to which
the coating is applied to a substrate comprising an automotive
vehicle.
20. A process according to claim 11 wherein the coating process
comprises application of the primer coating in the repair of an
automotive vehicle.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to Provisional U.S. Patent
Application Ser. No. 60/477,413, filed Jun. 10, 2003.
BACKGROUND OF THE INVENTION
[0002] Coatings used for the repair of a vehicle surface comprise
several layers of different coating compositions such as primer,
basecoat and clearcoat. Primer coating compositions are usually the
initial coating layer applied in a vehicle coating repair process.
The primer may be applied directly to bare metal or to an
electrocoated substrate. In refinish applications a primer may also
be applied to a substrate having one or more coating layers
thereon. It is desirable that the coating cures quickly and that it
provide a layer of paint that is sandable with sandpaper or other
abrasive to remove imperfections from the coating layer. Typically
the thickness of the coating layer is from 25 .mu.m to 100
.mu.m.
[0003] One class of coating compositions, well known for use in
primers, comprises a hydroxyl functional polymer, such as polyester
or acrylic polymer, and a polyisocyanate. These two components
react together after application to the substrate to form a
polyurethane coating. These compositions are often thus referred to
as 2K polyurethane coating compositions, although technically the
polyurethane is formed through crosslinking. 2K Polyurethane
primers of this general type have been known for at least 20
years.
[0004] One problem with using such 2K polyurethane primers is that
sufficient time must be allowed for curing to occur before it can
be sanded and topcoated. Typically a primer must cure for 2-4 hours
at ambient temperature. An additional drawback to polyurethane
primers is that they contain relatively high levels of organic
solvents. Due to environmental considerations there is a general
trend in the coatings industry towards coating compositions with
reduced solvent content.
[0005] Primer/sealant compositions curable under ultraviolet and
thermal conditions are disclosed in PCT/EP00/03401. These coating
compositions however require resins with ultraviolet curable groups
and thermally curable functionality such as isocyanate
functionality. Thermal cure must be applied in addition to the
ultraviolet cure to achieve adequate cure of the coating
composition, requiring additional energy expenditure and longer
curing times.
[0006] Primer compositions curable under ultraviolet conditions
only are disclosed in WO-01/74499 A1. This application discloses a
primer coating and process for applying a primer coating to a
substrate. This coating cures only under ultraviolet light.
[0007] The present invention provides a primer coating composition
curable under natural outdoor light or by ultraviolet lamp
radiation. The coating dries quickly, is sandable and provides
adhesion to bare metal, as well as corrosion and humidity
resistance.
SUMMARY OF THE INVENTION
[0008] This invention relates to a primer composition and a method
of applying a primer composition to a substrate. The present
invention provides a primer composition that can be cured by
exposure to UV radiation having a very low UV-B content and
substantially no UV-C content or under natural outdoor light within
2 to 5 minutes. The primer provides a tack free surface after
curing under these conditions and exhibits good sanding
characteristics, good hiding, and provides adhesion to cold rolled
steel as well as e-coated substrates and substrates having aged
coatings thereon.
[0009] The primer coating composition comprises: A one or more
compounds containing one ethylenically unsaturated free-radically
polymerizable group per molecule; B) one or more compounds
containing two or more ethylenically unsaturated free radically
polymerizable groups per molecule; C) one or more pigments, fillers
and/or dyes; D) less than 1.0% of one or more photoinitiators; and
compounds selected from volatile organic solvents and customary
additives and mixtures thereof.
[0010] The process of priming a surface comprises: i) applying a UV
radiation curable primer to the area to be primed; ii) exposing the
primer to natural outdoor light or UV radiation provided by one or
more UV lamps. The primer cures within 2 to 5 minutes under natural
outdoor light or by UV radiation provided by one or more UV lamps
having a UV-B:UV-A ratio of 1:1 or less and substantially no UV-C
content. In one embodiment the process can be operated easily and
safely in a typical automotive refinish bodyshop. The process is
adaptable to an OEM coating application environment as well. Little
or no organic solvent is emitted during the application and cure of
the primer and the primer can be applied and cured to a non-tacky
finish in a very short time.
DETAILED DESCRIPTION
[0011] This invention relates to a primer composition and a method
of applying a primer composition to a substrate. The UV radiation
curable primer comprises: component A comprising one or more
compounds containing one ethylenically unsaturated free-radically
polymerizable group per molecule, present in an amount between
5-50% by weight, more preferably 10 to 40% by weight and most
preferably 25 to 35% by weight; component B) comprising one or more
compounds containing two or more ethylenically unsaturated free
radically polymerizable groups per molecule present in an amount
between 5-50% by weight, more preferably from 10-40% by weight and
most preferably from 25 to 35% by weight; component C) comprising
one or more pigments, fillers and/or dyes is present in an amount
from 1-60% by weight, more preferably from 10 to 60% by weight;
component D) comprising one or more photoinitiators is present in
an amount from 0.1 to 0.98% by weight, more preferably form 0.1 to
0.95% by weight; component E) comprising volatile organic solvent
is optionally present in an amount from 0-20% by weight; and
component F) comprising customary additives is present in an amount
between 0.1-20% by weight, more preferably from 0.1 to 15% by
weight and most preferably from 0.1 to 10% by weight. All amounts
are based on total coating composition weight. All ranges of
amounts are intended to include each and every point within the
range.
[0012] In general, the type and level of component A are chosen to
give the composition a suitable viscosity and to dissolve
components B and D. The choice and level of component A also
affects the hardness of the coating. The type and level of
component B is chosen to provide suitable adhesion, flexibility,
hardness and solvent resistance. Preferably the ethylenically
unsaturated groups in component A and component B are principally
acrylate groups as this results in rapid cure rate.
[0013] Examples of compounds suitable as component A are alpha-beta
unsaturated aliphatic compounds such as 1-octene, 1-hexene and
1-decene, vinyl esters such as vinyl acetate, styrene, substituted
styrenes such as alpha-methylstyrene or p-methylstyrene, esters of
methacrylic acid and esters of acrylic acid. Preferably component A
is selected from alkyl esters of acrylic acid such as butyl
acrylate, t-butyl acrylate, isobornyl acrylate, isodecyl acrylate,
2-ethylhexyl acrylate, lauryl acrylate, cyclohexyl acrylate and
octyl acrylate. More preferably component A comprises isobornyl
acrylate and/or 2-ethylhexyl acrylate.
[0014] Examples of compounds suitable as component B include
diacrylates such as hexanediol diacrylate or tripropyleneglycol
diacrylate, triacrylates such as trimethylolpropane triacrylate,
alkoxylated trimethylolpropane triacrylate or pentaerythritol
triacrylate, polyacrylates such as pentaerythritol tetraacrylate or
dipentaerythritol hexaacrylate, urethane acrylates such as Ebecryl
8402, or Ebercryl 8301 available from UCB Chemicals or Actilane 251
available from Akcros Chemicals or unsaturated polyesters such as
polyesters prepared with maleic anhydride as one of the monomeric
components. Preferably component B comprises one or more urethane
acrylates, more preferably component B comprises a mixture of di-
and poly-functional urethane acrylates.
[0015] In principle component C may be any known pigment or filler.
Conventional pigments such as titanium dioxide iron oxide,
lithopone and zinc oxide can be included. Suitable fillers include
clays, barytes, mica, talcs, zinc sulfate, calcium sulfate and
calcium carbonate. Component C can include those pigments known to
inhibit corrosion such as strontium chromate, zinc phosphate and
barium metaborate. Preferred pigments and fillers are those that do
not interfere substantially with the radical cure. Preferably
component C comprises zinc phosphate, barium sulphate, and
talc.
[0016] The types and levels of pigments are chosen principally in
order to achieve excellent sandability and corrosion resistance,
while providing minimum cure time under outdoor natural light
conditions or under ultraviolet lamp exposure conditions as
specified herein. Preferably the levels and types of pigments and
fillers are chosen to achieve a pigment to binder ratio of between
0.8 and 2.0, most preferably between 1.2 and 1.8.
[0017] Primer compositions containing preferred pigments are often
transparent or translucent. In many cases it is desirable if the
thickness of the coating can be estimated during application. One
way of achieving this is to include a dye in the composition.
Suitable dyes include metal complex dyes such as the Zapon(R) range
available from BASF Aktiengesellschaft. When a dye is present, it
is preferably present at a level of 0.005-1% by weight based on the
total composition, more preferably 0.02-0.05%. An alternative way
of achieving this is to include a metal flake pigment in the
composition. Suitable metal flake pigments include aluminium flake
pigments such as the Stappa range available from Eckart-Werke. When
metal flake pigment is present, it is preferably present at a level
of 0.1-10% by weight based on the total composition, more
preferably 0.25-1%.
[0018] Component D can be any photoinitiator(s) capable of
generating free radicals when exposed to radiation having a UV-B:
UV-A ratio of 1:1 or less. Preferably the photoinitiator(s) are
capable of generating free radicals when exposed to radiation
having a UV-B:UV-A ratio is 0.2:1 or less, more preferably 0.05:1
or less and even more preferably 0.025:1 or less. Preferred
photoinitiators include acyl phosphine oxides, for example Irgacure
819 or benziketals such as Irgacure 651, available from Ciba
Specialty Chemicals. Preferably the primer contains 0.1% to 0.98%
by weight of component D.
[0019] The volatile organic solvent can be any solvent which will
dissolve components A, B, D and F. It can be an aliphatic or an
aromatic hydrocarbon such as Solvesso 100.RTM., a mixture of
aromatic solvents having an aromatic solvent content of 99.5% by
weight and comprising primarily C9-10 dialkyl and trialkyl
benzenes. Also suitable are toluene or xylene, alcohols such as
n-butanol or isopropanol, esters such as iso-butyl acetate, n-butyl
acetate, n-propyl acetate, methyl acetate or ethyl acetate, ketones
such as acetone, methyl isobutyl ketone or methyl ethyl ketone,
ethers, ether-alcohols or ether-esters such as ethyl
3-ethoxypropionate, propylene glycol methyl ether, propylene glycol
ethyl ether, propylene glycol n-propyl ether or propylene glycol
t-butyl ether or a mixture of any of these. Preferably one or a
combination of acetone, methyl ethyl ketone, ethyl
3-ethoxypropionate and n-butyl acetate are utilized.
[0020] The level and type of solvent used will depend on the
viscosity of the other components and the intended application
method. In a preferred embodiment the primer contains no volatile
organic solvent.
[0021] The primer composition may also contain, as component F,
conventional additives such as photosynergists, adhesion promoters,
pigment dispersants, flow aids, wetting aids and rheology
modifiers.
[0022] The process of priming a surface (preferably a vehicle or
vehicle component) comprises; i) applying a UV radiation curable
primer to the area to be primed; ii) curing the primer with natural
light or UV radiation provided by one or more UV lamps. The primer
composition is cured by exposure to UV radiation. When several
applications of primer are used, the primer can be cured after each
application or only after the final application. The ratio of UV-B
content to UV-A content of the radiation is 1:1 or less. Preferably
the UV-B to UV-A ratio is 0.2:1 or less, more preferably 0.05:1 or
less and even more preferably 0.025:1 or less. The radiation has
substantially no UV-C content. UV-A radiation is any radiation
falling within the 320-400 nm wavelength interval, UV-B radiation
is any radiation falling within the 280-320 nm wavelength and UV-C
radiation is any radiation falling within the 200-280 nm wavelength
interval. The UV light source applied has intensity ranges as
follows: UVA intensity is from 0.8 to 1.6 Joules/cm.sup.2, the UVB
intensity is from 0.001 to 0.5 Joules/cm.sup.2 and the UVC
intensity is from 0.001 to 0.3 Joules/cm.sup.2.
[0023] The radiation may be provided by any suitable UV lamp and
preferably the lamp(s) are positioned so that they are between 5
and 60 cm away from the surface of the primer. More preferably the
lamp(s) are positioned so that they are from 10 to 30 cm away from
the surface of the primer.
[0024] When the primer is cured by exposure to natural outdoor
light to cure, preferably the primer is exposed to the natural
outdoor light for 1 to 10 minutes. Outdoor natural light providing
curing conditions have an intensity of from 5 to 100
mJoules/cm.sup.2. In one embodiment the coating cured to a
non-tacky surface after 5 minute exposure to outdoor light having
an intensity of 45-65 mJoules/cm.sup.2.
[0025] When the primer is cured by lamp radiation, exposure to the
lamp radiation is for from 30 seconds to 10 minutes, more
preferably from 1 to 3 minutes. Alternatively, the primer may be
cured by exposure to a combination of both natural outdoor light
and UV lamp radiation. The outdoor visible light has a wavelength
of between 320 and 430 nm.
[0026] The spectral output of a given radiation source can be
measured with an energy dispersive spectrograph comprising a
monochrometer and light detector whose sensitivity is known at the
relevant wavelengths. The ratio of UB-B:UV-A is arrived at by
integrating the intensities of spectral output in the respective
wavelength ranges. An example of a suitable instrument is the model
440 spectrometer available from Spectral Instruments, Tucson Ariz.,
USA.
[0027] Following cure, the primer can be sanded using sand- or
glasspaper prior to topcoating. If any sticky uncured surface layer
exists, it is removed by wiping the surface of the primer with a
volatile organic cleaning solvent prior to optionally sanding and
topcoating. The volatile organic cleaning solvent can be an
aliphatic or aromatic hydrocarbon such as Solvesso 100(R), toluene
or xylene, an alcohol such as n-butanol or isopropanol, an ester
such as butyl acetate or ethyl acetate, a ketone such as acetone,
methyl isobutyl ketone or methyl ethyl ketone, an ether, an
ether-alcohol or an ether-ester, water or a mixture of any of
these.
[0028] The primer may be topcoated with any suitable refinish
system in order to achieve the desired final color and appearance.
For example the primer can be coated with a waterborne basecoat
such as Glasurit L-90 available from BASF, followed by application
of a soventborne urethane clearcoat such as 923-450 available from
BASF. Alternatively the primer can be topcoated with a solventborne
basecoat such as Glasurit L-55 available from BASF, followed by
application of a soventborne urethane clearcoat such as 923-450
available from BASF. Alternatively it can be topcoated with a
solventborne single layer urethane topcoat such as Glasurit 22 line
available from BASF.
[0029] The process is particularly suited to, but not limited to,
carrying out spot repairs to damaged vehicles. A spot repair refers
to a repair of damage that is limited to small area of a vehicle
panel, usually less than 50 cm. According to the present invention
there is also provided a substrate coated or partially coated by
the process of the invention.
[0030] The invention will now be illustrated by means of the
following examples.
EXAMPLES
Example 1
[0031] Photoinitiator Solution
[0032] The following ingredients were combined with stirring to
form the photoinitiator solution: 8.3 grams Irgacure 819 and 1.7
grams Irgacure 651, both photoinitiator compositions available from
Ciba and 90 grams acetone.
Example 2
[0033] Primer Coating Compositions
[0034] A primer paste formulation was prepared as follows:
1 Amount Ingredient (grams) Difunctional Urethane Acrylate.sup.1
11.1 Hexafunctional Urethane Acrylate I.sup.2 5.6 Hexafunctional
Urethane Acrylate II.sup.3 5.6 Tripropylene glycol diacrylate 7.0
Solvent 6.3 Rheology Control Agent 0.7 Dispersing Agent 0.4 Talc
16.7 Barium Sulfate 16.7 Zinc Phosphate 16.7 Mono-oxide black 0.3
Methyl ethyl ketone 5.7 .sup.1Ebercryl 8402 from UCB Chemicals
.sup.2Ebercryl 8301 from UCB Chemicals .sup.3Developmental Ebercryl
from UCB Chemicals
[0035] The primer was formed by the addition of the primer paste to
the following:
2 Ingredient Amount (grams) Primer Paste Formulation 174.1 169.5
165.8 155.8 Photoinitiator Solution from 10 15 19 30 Ex. 1 Acetone
20.0 15.0 11.0 -- Acidic Adhesion Promoter 4.3 4.3 4.3 4.3
[0036] The ingredients were mixed and sprayed over cold rolled
steel that had been sanded with 220 grit sandpaper. The films were
applied in two coats with a one-minute flash dry between coats.
After the second coat was applied, the film was flash dried for 3
minutes then cured with an ultraviolet lamp Panacol 450 for 2
minutes where the substrate was at a distance of 10 inches from the
light source.
3TABLE 1 Evaluation of Primers for Surface Cure Following curing as
set forth above, the panels were subjected to surface tests as
follows. (1) Sand was applied to the coated panel, rating is how
much of the area was covered by large sand sphere- (100% is
completely covered); (2) cotton balls were pressed on to the panel
surface-rating is % of surface covered by cotton ball fibers; (3)
paper was placed on a panel and a 100 gram weight applied for one
minute-passed if paper fell off, failed if paper stuck to the
panel. Test results are as follows Sample 1 2 3 Control* %
photoinitiator 0.5 0.75 0.95 % adherance to surface of panel Sand
60 40 20 100 Cotton Ball 15 15 15 80 Paper passed passed passed
Failed *UV Primer Surfacer PPG DS1002
[0037]
4TABLE 2 Evaluation of Primers for Humidity Resistance and Adhesion
Sample 1 2 3 Control* % Initial 100 100 99 100 Adhesion % 7 day 100
100 100 100 Adhesion *UV Primer Surfacer PPG DS1002
[0038] Coatings were prepared according to Example 2 and applied to
a cold rolled steel (CRS) substrate in two coats with a one-minute
flash dry between coats. After the second coat was applied, the
film was flash dried for 3 minutes then cured under one of the
following conditions:
[0039] 1. Exposure to daylight in Whitehouse, Ohio on May 6, 2003
at a visible light wavelength of approximately 340-430 nm and
intensity of 45-65 mJoules/cm.sup.2, for time indicated;
[0040] 2. Exposure to ultraviolet lamp Panacol 450 (UVA only) for
time indicated where the substrate was at a distance of 10 inches
from the light source;
[0041] 3. Exposure to a mixture of UVA/B/C under ultraviolet lamp
with a D-bulb, 2 passes, at a UVA intensity of 1.6 Joules/cm.sup.2,
a UVB intensity of 0.5 Joules/cm.sup.2, and a UVC intensity of 0.3
Joules/cm2 per pass.
[0042] Adhesion was determined by the X-scribe test, the test score
indicating the amount of paint remaining following the test.
Example 3
[0043]
5 Primer Cured in Outdoor Natural Light The following ingredients
were mixed together to form the primer composition. Amount
Ingredient (grams) Difunctional Urethane Acrylate.sup.1 10.6
Hexafunctional Urethane 5.3 Acrylate I.sup.2 Hexafunctional
Urethane 5.3 Acrylate II.sup.3 Tripropylene glycol diacrylate 6.7
Solvent 6.0 Rheology Control Agent 0.7 Dispersing Agent 0.35 Talc
15.9 Barium Sulfate 15.9 Zinc Phosphate 15.9 Mono-oxide black 0.26
Methyl ethyl ketone 5.4 Acetone 8.6 DS 3194 0.8 Photoinitiator 0.16
Adhesion promoter 2.1 .sup.1Ebercryl 8402 from UCB Chemicals
.sup.2Ebercryl 8301 from UCB Chemicals .sup.3Developmental Ebercryl
from UCB Chemicals
[0044]
6TABLE 3 Adhesion of Primer to Cold Rolled Steel Exposure 24 Hour
Type of Time Initial Post Humidity Recovery Exposure (minutes)
Adhesion Adhesion Adhesion Outdoor Natural 5 95 95 99 Light 10 99
99 95 20 95 99 99 UVA lamp 2 95 95 95 2 99 99 95 UVA/B/C lamp 95 95
95 95 90 95
* * * * *