Note: Descriptions are shown in the official language in which they were submitted.
WO 95132092 ~ ~ ~ a ~ 2 7 PCTlUS94105836
PIGMENTED MIRROR RESIN BACKINGS AND MIRRORS
Field of the Invention __
This invention relates to improved hydrophilic
stable coatings capable of protecting thin metallic films
such as those on mirrors from corrosive decomposition.
More particularly, the present invention relates to
improved coatings for mirror backings which comprise
combinations of organic resin polymers in aqueous or non-
aqueous mediums and soluble salt and contaminant-free
antioxidant scavenger pigments. Aqueous coatings (paint)
for mirrors have not been available until the development
of this invention. Accordingly, this invention provides
aqueous coatings or paints as mirror backings.
B~ckaround of the Invention
Mirrors are made by the successive application of
1$ various metals, preferably silver and copper films of
between 800 angstroms and 1,$00 angstroms in thickness on
suitable substrates of glass or plastics such as
polycarbonates, by wet chemical plating processes or
vacuum metallizing, followed by a paint coating
application, usually known as a mirror backing.
Metallic layers are applied to glass substrates by
one of three general methods, 1) electroplating, :2)
chemical deposition, or 3) galvanic deposition. Galvanic
deposition is the current method of choice and is now
2$ widely used. Usually a silver layer is applied and a
' copper layer deposited on the silver layer. The copper
layer is important to provide good adherence of the
backing to the silver layer.- The present invention
employs the galvanic deposition system.
CA 02191127 2002-11-14
2
It is known that reflective silver layers on
mirrors, even when protected by "backing" coatings are
extremely sensitive to corrosive decomposition when
exposed to moisture, contaminants in the atmosphere,
salt, hydrogen sulfide, ammonia, and chlorides, which are
present in domestic environments. It is also known that
zinc phosphate or zinc salts of dicarboxylic acids,
commonly applied as corrosion inhibitors in protective
primers on steel or aluminum, contrary to expectations,
do not work well in mirror backing coatings and actually
exhibit corrosive action on the silver layer.
Various mirror backing coatings have been proposed
by the prior art, including coatings which comprise
mixtures of an organic resin and pigment. For example,
U.S. Patent No. 4,707,405 to Evans et al, discloses a
mirror backing coating which comprises an organic film
forming resin and a cyanamide salt of a non-lead metal.
The cyanamide salt is said to be a salt of group IIA-or
group IIB metal such as calcium, zinc or magnesium, with
the preferred salt being calcium cyanamide. It is
believed that the calcium and magnesium cyanamides have
not been successful because both are water soluble,
highly alkaline "non-pigment" products which interfere in
detrimental fashion with curing processes of coating
systems organic material. In addition, they exhibit only
marginal corrosion preventive activity on silver, which
is expected considering that typical technical grade
calcium cyanamides contain considerable amounts (e.g., 1~
CaSz) of soluble sulfide species as impurities .
Therefore, the zinc cyanamides known heretofore have not
gained commercial acceptance.
In US 5,314,532, an invention is set forth which
provides superior anti-corrosion mirror backing using a
non-lead pigment.
CA 02191127 2002-11-14
3
The present invention provides improved paint and
coating formulations for mirror backings which have
excellent long term corrosion preventive protection of
the mirror reflective silver layer utilizing a novel
resin formulation.
Summary of the Invention
It is accordingly one object of the present
invention to provide an improved paint or coating to
protect thin metal films such as silver and copper
against corrosive decomposition.
A further object of the present invention is to
provide an improved mirror backing paint coating,
including aqueous based coatings, which contain a
cyanamide antioxidant pigment, and which is capable of
protecting thin metallic films from chemical
decomposition while exhibiting hydrolytic stability.
A further object is to provide a novel resin backing
which provides an effective non-corrosive mirror backing
With any antioxidant pigment.
The present invention also concerns a mirror backing
formulation for forming a protective coating for
application over at least one thin metallic coating on a
mirror, said formulation comprising:
(a) an organic resin polymer selected from the
group consisting of aqueous or non-aqueous mixtures of
alkyd resins and acrylic resins, each of said resins
being used in combination with a melamine resin; and
(b) an anti-corrosion amount of an antioxidant
scavenger pigment comprising a cyanamide compound of a
metal, wherein said metal is selected from the group
consisting of zinc, nickel, cobalt, lead, mixtures
thereof and blends;
CA 02191127 2002-11-14
3a
and wherein the mixture of melamine resin with
said alkyd resin or acrylic resin is effective to form a
hard resin backing over said metallic coating to minimize
corrosive effects.
In accordance with another aspect, the present
invention also provide a mirror backing formulation for
forming a protective coating on a mirror back having a thin
metal layer thereon, said protective coating comprising a
durable and long term protective coating, and comprising
the combination of:
(a) an organic resin polymer selected from t he
group consisting of alkyd resins, acrylic resins, acrylic
modified alkyd resins, polyurethane oils, vinyl half de
polymers, vinyl halide copolymers, non-oil bas ed
urethane, and phenol-formaldehyde resins contained in
aqueous or non-aqueous medium; and
(b) an anti-corrosion amount of a substantial 1y
soluble salt-free antioxidant scavenger pigment
comprising a cyanamide compound of a metal, said
cyanamide compound of said metal containing no more than
about 0.5o by weight of said soluble salts and wherein
said metal is selected from the group consisting of zinc,
nickel, cobalt, lead, mixtures thereof, and blends.
Other objects and advantages of the present
invention will become apparent as the description thereof
proceeds.
In satisfaction of the foregoing objects and
advantages, there are provided by the present invention,
protective mirror backing formulations which comprise the
CA 02191127 2002-11-14
3b
combination of a resin polymer contained in an aqueous or
non-aqueous medium, and one or more refined cyanamide
antioxidant scavenger pigments, the pigment in one
embodiment being essentially salt-free and essentially
contaminant free. The soluble antioxidant scavenger
cyanamide pigment may be based on metals such as lead,
zinc, nickel, cobalt, etc., and especially includes
complexes of any of these metals with cyanamides and di-
cyanamides.
WO 95132092 PCTIUS94/05836
219ii2~
-4-
Also provided by the present invention is a method
for the protection of thin metal films contained on the
backs of glass or plastic objects such as mirrors which
comprises applying thereto an improved paint or coating
which comprises a combination of an organic resin polymer
contained in an aqueous or lion-aqueous medium in
combination with one or more soluble cyanamide
antioxidant scavenger pigment, such as essentially salt-
free and contaminant-free metal cyanamide pigments.
Description pf Preferred Embodiments
According to one aspect of the present invention, it
has been discovered that the metallic (e. g. silver)
reflective layers of mirrors which contain protective
coatings thereon have. a marked intolerance to the
presence of trace amounts of soluble salt contaminants
which usually accompany the pigment component of the
coating system. This is a particular problem with
pigments which can generate ionic species disassociation
in aqueous media. It has been discovered that the
presence in trace amounts of these soluble salt
contaminants is accountable for the poor corrosion
preventive performance of some commercially available
pigment grade products in mirror backing applications.
According to a further embodiment, the present
invention, it has been discovered that the metallic (e. g.
silver) reflective layers of mirrors which contain
'protective coatings thereon are substantially improved by
use of a melamine based resin formulation which provides
excellent non-corrosive mirror backings with any metal
containing cyanamide antioxidant-pigment.
In the prior art, known manufacturing procedures
provide pigments such as zinc cyanamide by treating zinc
oxide with an excess of urea or di-cyanamide under
nitrogen or vacuum, initially at 135° to 200°C and then
CA 02191127 2002-11-14
_5_
calcinating at 600°-800°C for two hours. The
shortcomings of this energy intensive procedure, are that
it yields a product of relatively "closed" texture,
characterized by low specific surface area and porosity,
and consequently of reduced reactivity. Zinc cyanamide
produced by calcination does not exhibit the high degree
of corrosion preventive activity necessary in mirror
backing systems, and thus, cannot be considered as
"pigment" grade products for mirror applications.
I0 Also known are wet manufacturing processes (U. S.
1,948,106 and 3,039,848) which produce zinc cyanamide by
precipitation by reacting soluble zinc salts with water
soluble, usually alkali, salts of hydrogen cyanamide,
expressed as:
I5 ZnCOj + 2NH3 -- ZnNCN + 3H20.
The appearance in the system of the soluble by-
products of the reaction is the major disadvantage of
these procedures. To eliminate them, extensive washing
is required whereby large amounts of contained waste
20 water are generated. More importantly, due to the fact
that complete elimination of the soluble salt
contaminants are usually not feasible, the quality of
pigment grade zinc cyanamide produced according to such
procedures is affected by the presence of trace amounts
25 of usually corrosion promoter soluble by-products.
It is also known from British Patent No. 905,959
(1962), and Russian Patent 327,783 that basic mono-zinc
~cyanamide may be produced by initially preparing an
aqueous solution of hydrogen cyanamide by reacting
30 dissolved calcium cyanamide with H2S0~ or COz and
subsequently reacting the intermediate product with a
zinc oxide slurry at 20°C for one to two hours. This
reaction proceeds as follows:
Zn0 + HZO + H~NCN - ZnNCN + 2H20.
WO95l32092 2191 12l PCTIUS94f05836
-6-
After filtering the product and drying, this product
typically contains 83-85$ of zinc cyanamide, 13-15$ of
zinc oxide, and 2$ water. One of the shortcomings of
this manufacturing procedure is related to the process
for preparation of the hydrogen cyanamide. As a result,
the final product contains considerable amounts of the
carbonic acid and sulfuric acid ~n soluble form. Sulfur
containing impurities, representing 1-2$ of technical
grade calcium carbides, the usual raw material of the
calcium cyanamide manufacturing processes, are
accountable for the appearance of soluble sulfide species
in the hydrogen cyanamide. gor obvious reasons, the
applicability in mirror backing formulations-of a pigment
grade zinc cyanamide produced by this process- is rather
limited.
By this invention unpurified as well as salt-free
and contaminant-free pigments are provided from which
aqueous and non-aqueous mirror backing coatings are made
possible, the coatings having outstanding anti-corrosion
and durability properties and are useful for long term
protection. In the pasty water soluble-salts would
create hydrophilic instability and incompatibility with
the thin metallic films resulting in chemical
decomposition and failure. The use of the novel resin
formulation with unpurified and purified, e.g. salt-free
and contaminant-free antioxidant cyanamide pigment
coatings of this invention offer additional performance
'features with respect to the chemical bonding of the
coating and the substrate.
In this specification, the expression, "salt-free"
means that the pigment contains not more than about 0.5$
by weight of water soluble -free salts and impurities
(contaminants) incompatible with thin silver/copper
metallic films and the like. "Antioxidant" means a
pigment or pigments which inhibit oxidation of the
WO 95/32092 Z ~ g 112 7 PCT~S94~'05836
-7-
substrate or metal layer and prevents saponification of
the coating. "Scavenger" means a pigment or pigments
which effectively display the ability to neutralize free
sulfide and chloride ions produced or present during the
corrosion process.
There are various physical and chemical properties
which any pigment must have in order to function as a
corrosion preventive component in a paint and coating
system, particularly in a protective coating. Thus, the
pigment must have dispensability in organic media, either
aqueous or non-aqueous, relatively low oil absorption,
low water solubility, neutral or slightly alkaline
hydrolysis in the absence of water- soluble salts or
inorganic contaminants, and more critically, the capacity
to interact with and provide- specific -corrosion
promoting electro-chemical processes which occur on the
protective surface. This capacity of a pigment grade
product derives from its chemical compositional
structure. However, its corrosion retardant activity as
manifested -in protective coatings must be determined by
its water solubility.
Soluble salt-free contaminant-free antioxidant
scavenger pigments function as a corrosion preventive
component of protective coatings as in mirror backing
coatings due to the optimal water solubility and
hydrolyzable pH. However, it is reasonable to suppose
that the characteristics of the product in its hydrogen
'sulfide- scavenger capacity and specifically the
antioxidant nature of the cyanamide moiety, generated by
solubilization during interaction of the pigment with
corrosion promoting processes, are primarily accountable
for the protective activity provided.
According to one aspect of this invention, soluble
salt-free and contaminant-free pigments are provided
which enable the production of mirror backing
CA 02191127 2002-11-14
-8-
compositions which exhibit durability and good appearance
over long periods of time. According to this invention,
soluble salt-free and contaminant-free metal cyanamide
pigment suspensions are provided which are excellent
quality pigments for mirror backings.
In another aspect of the invention, metal cyanamide
pigments may be used which have not been purified or are
not salt-free such as the cyanamide pigments disclosed in
U.S. Patent Nos. 4,707,405, U.S. Patent 1,948,106, U.S.
Patent 3,039,848, British Patent No. 905,959 and Russian
Patent No. 327,783. The novel resin formulations of the
invention enable the effective use of any metal cyanamide
pigment as a mirror backing pigment with excellent anti-
corrosive properties.
The metal cyanamides may be a basic cyanamide salt
or a complex salt which includes one or two or more
metals in combination as well as mixtures and blends.
The metal may be any metal of groups IIA and IIB of the
Periodic Table, preferably lead, zinc, nickel, cobalt, or
mixtures thereof.
Especially preferred materials are complex cyanamide
salts which include two metal molecules complexed
hydrogen cyanamides including Neutral zinc
Cyanamide, Nickel Bis-Cyanamide, Cobalt Bis-Cyanamide,
Zinc Nicke 1-Dicyanamide, Zinc Cobalt-Dicyanamide, and
mixtures thereof, as well as equivalent materials.
Neutral Zinc Cynamide is expressed as:
,OH OH
Zn
Zn
0H ~- \ NCN"H20 + ~N-C=N+H2NCN-2ZnC~N+2H20
~H H / Zn'~
Zn
OOH
R'O 95132092 2 T 9 1 1 2 7 PCT/U594'/0583G
_g-
Acid Nickel Bis-Hydrogen Cyanamide:
Ni2 N C~N
~ N-C~N
H
Acid-Cobalt Bis Hydrogen Cyanamide:
H
~ N-C~N
Co2+
~ N-C~N
H~
The salt free and contaminant free pigments of this
type were obtained for use in this invention from Wayne
Pigment 'Corporation, Milwaukee, Wisconsin, USA and are
available commercially.
COMPARATIVE DATA FOR
MONO-ZINC CYANAMIDE
Wayne PigmentB.P. #909959 U.S. #1968108
ZnNCN 9394% 8385% 50%
ZNo < t% 1315%
ZnCO' - ' ~%
NCN Content 37.0% 19.5% 18.5%
Neutral Zinc 100.0% ~.0% 50.096
NCN
Basic Zfnc NCN 0 31% U.K.'
HZo S.s% z% -
* Contaminants Present
The mirror backing composition of this invention
comprise organic film forming resins which are either
' water soluble (aqueous) or solvent soluble (non-aqueous).
The organic film forming resin should be one which is
- compatible with the thin metallic film and will not
WO 95132092 PC1YU594105836
2191127
-lo-
promote deterioration and discoloration of the film.
Thus, the resin should not contain functional groups
which are reactive with the metal. Preferred organic
film forming resins are those based on alkyd resins or
acrylic resins which may further contain acrylic modified
alkyd resins, polyurethane oils, vinyl halide.. polymers or
copolymers, epoxy resins, urea resins, non-oil based
urethane, phenol-formaldehyde resins. The film forming
resin must contain melamine resins for cross-linking
unless the metal cyanamide pigment is essentially salt-
free and contaminant-free. The resulting resins are
curable by air drying, baking, ultra violet curable, or
any other resin which is compatible with the soluble salt
contaminant-free antioxidant pigment. Suitable solvents
for non-aqueous resins comprise various aromatic and
aliphatic hydrocarbons, alkyl esters, glycol ethers, and
lower alkyl alcohols. Suitable solvents for aqueous
resins comprise various glycol ethers, alkyl alcohols,
and other water miscible solvents, all of which are known
in the art.
A special feature of the invention is the provision
of aqueous based coatings for mirrors as described
herein. To Applicants' knowledge,-such aqueous based
mirror coatings have not been known heretofore.
In non-aqueous based systems, the components should
be present in the following amounts:
Component Amount t cat . $1
Resin 20-50
Solvent 10-40
Pigment 3-65
In aqueous based systems, the components should be
present in the following amounts:
WO 95/32D92 2 T 9112 7 PCT~S941105836
-11-
(~.'OmT~Onent _ AILIOllnt ( wt . $ 1
Resin 10-45
Solvent 5-25
Pigment 3-65
Water (preferably distilled) 10-40
' It is preferable that the cyanamide antioxidant
pigment be contained in the resin coating in the amount
of about 3~ to about 65~, preferably about 7~ to 30$ by
weight of the composition based on pigment solids. It is
also preferable that the pigment have a particle size of
less than about 0.25 microns.
The composition can also contain other components or
additives, such as driers, flow control aids, anti
settling agents, dispersing aids, and the like, and
mixtures thereof.
A particularly preferred coating formulation far
such pigments comprises a mixture of a specially
formulated mixture of alkyd resin or acrylic resins
together with a melamine resin, solvents, additives and
pigment. It has been discovered according to the present
invention that the mixture of an alkyd resin or acrylic
resin with melamine in combination with the other
ingredients provide a resin formulation which will
provide excellent non-corrosive characteristics as a
mirror backing with any cyanamide pigment, including
pigments which contain greater than 0.5$ of soluble
salts. Apparently the components of the resin
formulation form cross-links in the mixture so as to form
.a very hard resin backing for the mirror. The hardness
of the resin backing prevents the corrosive effect
normally encountered with most resin backings.
Accordingly, this resin formulation can be used with any
metal cyanamide antioxidant pigment.
WO 95/32092 21911 ? ~ PCT/US94105836
-12-
The preferred resin formulation contains the
following amounts:
Incxredients _ Parts bv, Weicrht-
Allc_yd Resin or Acrylic Resin 25-50-
Melamine Resin 3-~
Solvent 5-15
Pigment 2-10
This formulation is normally used with fillers and
extenders in a manner known to the art.-
The alkyd resin is preferably a modified alkyd resin
composition which is a mixture of dehydrated castor oil,
linseed oil, phenolic resin, glycerin, phthalic anhydride
and aromatic solvents.
The acrylic resin is any acrylic acid or methacrylic
acid, or ester, or mixture thereof, as known in the art.
A preferred acrylic resin system is available from Dock
Resins Corporation under the trade name TA55-2.
A particularly preferred formulation of this type is
as follows:
lnaredients _ . . Parts bv.,Weicrht
Modified Alkyd or Acrylic Resin 30-40
Melamine Resin 3-10
Ester Solvents 10-15
Alcohols 5-10
Pigments 5-15
The process of the invention for use of the.coating
comprises applying the composition of the invention to a
thin metallic film, preferably such film on a glass
substrate such as a mirror. _ The composition of the
invention can be applied to the thin metallic film by any
conventional method such as coating, roll coating,
curtain coating, or spraying. The composition is
preferably applied to the thin metallic film in a
WO 95132092 2191 12 7 PCT/US94105836
-13-
thickness of about 0.5 mil to about 3.5 mils. The
composition is cured on the,mirror by simply air drying,
force heat drying or baking.
The following examples are presented to illustrate
the invention but the invention is not to be considered.
as limited thereto. In the examples, parts are by weight
unless otherwise indicated.
EgAMPLE
I
The following pigments were obtained from Wayne
Pi gment Corp.
NE UTRAL MONO-ZINE CYANAMIDE
8 Zinc as Zn..............................57.7 58.3
-
~ N as N..................................24.7 24.9
-
~ Zinc Cyanamide..........................93.0 94.0
-
~ Crystal Water...........................05.0 06.0
-
COBALT
BIS-HYDROGEN
CYANAMIDE
~ Cobalt as Co ...........................39.9 40.3
-
~ N as N .................................37.0 37.4
-
8 Co Bis-Hydrogen Cyanamide .............93.1 94.1
. -
ZINC-NICKEL
DICYANAMIDE
~ Zinc as Zn..............................51.2 51.8
--
8 Nickel as Ni............................ 4.3 4.5
-
8 N as N .................................25.9 26.9
-
~ Cyanamide as NCN........................92.7 93.7
-
~ Crystal Water........................... 4.4 5.4
-
'ZINC-COBALT
DICYANAMIDE
~ Zinc as Zn..............................49.6 49.9
-
~ Cobalt as Co............................ 5.6 5.9
-
$ N as N..................................26.4 27.4
-
~ Cyanamide as NCN........................93.0 94.0
-
$ Crystal Water........................... 4.3 5.3
-
WO 95!32092 ~ PCTIUS94l05836
-14-
EXAMPLE II . _
PREPARATION OF MIRROR BACfCING COATING FORMULATION$_
A Mirror Backing Paint Formulation is prepared by
mixing a soluble salt contaminant-freecyanamide pigment
as described below, obtained from Wayne Pigment Corp.,
with a resin or resins as listed in the following tables.
The initial dispersion mirror-backing coating formula is
ground to 6+ns Hegman and, allowed to stand overnight at
room temperature. The non-aqueous material is reduced
l0 with solvent (Xylo1) and the aqueous material -reduced
with D.I. water to applied viscosity of 35 seconds on a
Number 3 G.E. Zahn Cup, and subsequently drawn down on
pre-metallized (silver/copper) 12 X 12 inch, 1/4 inch
glass mirror panels with a 3 mil Bird draw down path bar
and allowed to flash dry for two minutes at room
temperature. The coating is then baked for four minutes
at 350°F. to yield 1.5 dry film-mils, then the mirror is
aged 24 hours after which 3 inches is cut and removed
from all four edges leaving a 6 X 6 inch panel for
testing. The cut panels are then placed in a Salt Spray
cabinet at 45 degree angles, exposed to.100~ humidity and
a 20~ salt solution at 95°F and evaluated every 150 hours
of exposure for a total for 300 hours. The panel edges
are evaluated for degree of edge creep (metal
decomposition/discoloration) expressed in millimeters.
The face of the mirror is also evaluated for field
spotting, pin holes, hazing, and metal decomposition.
The following table sets forth both aqueous and non-
aqueous paint/coating formulations as mirror. backing
compositions of this invention.
W095132092 , PCT/US94/05836
-I5-
EgAMPLE 1 ..
TABLE I
Typical paint/coating, i.e. mirror backing formulations
are made up of the following components:
A) NON-AQUEOUS MIRROR BACKING FORMULATIONS
Components 1A 2A 3A 4A 5A 6A 7A
1. MEDIUM OIL 40.0 40.0 40.0 40.0 40.0 40.0 40.0
MODIFIED ALKYD
or
ACRYLIC
1 [) 2. MELAMINE RESIN4.7 4.7 4.7 4.7 4.7 4.7 4.7
4.7
3. TALC 17.5021.5021.50 18.5018.5021.50 25.00
4. PIGMENT 10.0010.0010.00 10.0010.0010.~ 10.00
MEfHYLETHYL KETOXINE0.20 0.20 020 0.20 0.20 020 0.20
12'~ COBALT OCTOATE0.20 0.20 0.20 0.20 020 020 0.20
DRIER
106 CALCIUM OCTOATE0.40 .40 0.40 0.40 0.40 0.40 0.40
DRIER
XYLENE 18.0 78.0 18.0 18.0 78.0 18.0 78.0
5. ZINC CYANAMIDE9.00 - - ' - - -
2O PIGMEM
6. NICKEL BIS - 5.00 - - - - -
CYANAMIDE
PIGMENT
7. COBALT BIS - - 5.00 - - - -
CYANAMIDE
PIGMENT
8. ZINC NICKEL - - - 8W - - -
DICYNAMIDE PIGMENT
9. ZINC COBALT - - - - 8W - -
DICYANAMIDE PIGMENT
70. LEAD ZINC - - - - - 5W -
CYANAMIDE
PIGMENT
CONTROL
TOTALS 100.00100.00100.00100.00100.00700.00100.0D
W 0 95/32092 ~ PCTIUS94/05836
-16-
B) AQUEOUS MIRROR BACKING FORMULATIONS
Components 1B 2B 3B 4B 5B 6BA 78
1. WATER SOLUBLE 30.0033.6033.60 30.0030.0030.00 33.60
ACRYLIC RESIN
S TRIE7HYLAMINE 2.00 2.00 2.00 2.00 2.00 2.00 2.00
(TEA)
2. TALC 6.00 5.00 5.00 7.00 7.00 10.00 10.00
3. PIGMENT 10.0010.0010.00 10.001D.0010.00 10.00
ETHYLENE GLYCOL 6.50 6.50 6.50 6.50 6.5D 6.50 6.50
MONOBUTYLETHER
I~ BUTYL ALCOHOL 2.50 2.50 2.50 2.5D 2.50 2.50 250
'
4. MELAMINE RESIN10.0011.2011.20 tO.OD10.0010.00 11.20
DI-WATER 24.0024.2024.20 24.0024.0024.00 24.20
5. ZINC CYANAMIDE9.00 - - - - - -
PIGMENT
ZS 6. NICKEL BIS - 5.00 - - - - '
CYANAMIDE
PIGMENT
7. COBALT BIS - - 5.00 _ _ - _
CYANAMIDE
PIGMENT
8. ZINC NICKEL - - - gW - - -
2O DICYNAMIDE PIGMENT
9. ZINC COBALT - - - - $W - -
DICYANAMIDE PIGMENT
t0. LEAD ZINC - - - - - SW -
CYANAMIDE
PIGMENT
ZS CONTROL D
TOTALS 100.00100.00100.00100.00100.00100.00100.00
TABLE II . _ .
SALT SERAY TEST RESULTS
TABLEI 1A 2A 3A 4A 5A 6A 7A
30 150 HRS./EDGE CREEP .5mm .tmm .tmm Omm Omm Omm 7mm
150 HRS./FIELD AREAISPOTS Pass Pass Pass Pass Pass Pass Fail
300 HRS (EDGE CREEP tmm .5mm .40mm I I I Omm ~
.5mm .40mm l0mm
W0 95132092 PCTIU594105836
Zi91127
-17-
HRS./FtELD AREAISPOTS ~ Pass I Pass I Pass ~ Pass ~ Pass ~ Pass
i
TABLEI 1B 28 38 48 5B 6B 7B
150 HRS./EDGE CREEP .5mm tmm tmm .Smm.Smm .5mm l5mm
t50 HRS.IFIELD AREAISPOTS Pass Pass Pass PassPass Pass Fail
300 HRS./EDGE CREEP 20mm 2.Smm 2.Dmm tmm .90mm .5mm 23mm
300 HRS.IFIELD AREAISPOTS Pass Pass Pass PassPass Pass Fail
The following notes explain the components of the
compositions of Table I.
A) Non-Aqueous: Acrylic Resin; NVW 50~ Solvernt
nObutylacetate Acid No. = 12. 1) Medium Oil
Modified.Alkyd; NVW 50~ Solvent Xylol, Acid Na.
12 or; 2 ) Melamine Resin, NVW 84$ Polymeric,
solvent butanol; 3) Talc; NVW 100$, Microfine
magnesium silicate compatible with metals; !E}
Pigment; NVW 100, 96.0 Titanium Dioxide, 4.08
Carbon Black compatible with metals; 5) Zinc
Cyanamide NVW 100, Soluble Salt Contaminant-
Free, Wayne Pigments; 6) Nickel Cyanamide NEW
100--Soluble Salt Contaminant-Free; Wayme
Pigments; 7) Cobalt Bis-cyanamide NVW 100
Salt-Free, Wayne Pigments; 8) Nickel Zinc
Cyanamide 14.0 Nickel Bis-cyanamide; 86.0$
Zinc Cyanamide; Soluble Salt Contaminant-Free,
. Wayne Pigments; 9) Cobalt Zinc Cyanamide 14~;
Cobalt Bis-cyanamide; 86.0 Zinc cyanamide,
Soluble Salt Contaminant-Free; Wayne Pigments;
10) 33.5 Zead Cyanamide; 66.5 Zinc Cyanamid.e;
Soluble Salt Contaminant-Free; Wayne Pigments
B) Aqueous: 1) Water Soluble Acrylic Resin; rfVW
70~; Solvent, 2-butoxyethanol, compatible with
WO 95132092 219112 7 PCTIUS94105836
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metals, Soluble Salt Contaminant-Free; Wayne
Pigments; 2) Talc, NVW 100% Microfine,
Magnesium Silicate compatible with metals; 3)
Pigment: NVW 100%; 96.0% Titanium Dioxide, 4.0%
Carbon Black compatible with metals; 4)
Melamine resin, NVW 84%, Polymeric, Solvent
Butanol; 5) Zinc Cyanamide NVW 100%, Soluble
Salt Contaminant-Free, Wayne Pigments; 6)
Nickel Cyanamide NVW- 100%, Soluble Salt
Contaminant-Free; Wayne Pigments; 7) Cobalt
Bis-cyanamide NVW 100%, Soluble Salt
Contaminant-Free; Wayne Pigments; 8) Nickel
Zinc Cyanamide 14%, Nickel Bis-cyanamide, 86%
Zinc cyanamide, Soluble Salt Contaminant-Free;
Wayne Pigments; 9) Cobalt Zinc cyanamide; I4%
Cobalt Bis-cyanamide; 86% Zinc cyanamide;
Soluble Salt Contaminant-Free, Wayne Pigments;
IO) Lead Zinc cyanamide; 33.5% Lead cyanamide;
66.5% Zinc cyanamide, Soluble Salt Contaminant
Free; Wayne Pigments.
The non-aqueous mirror backing system of Table 1A
was evaluated after 20% salt spray exposure for..150-300
hours respectively. The soluble salt contaminant-free
antioxidant pigments performed well as inhibitors against
corrosion of the silver/copper layers and ultimately
blocked metal decomposition.
The aqueous mirror backing-composition of Table 1B
was evaluated after 20% salt spray exposure for 150-30D
hours, respectively. The soluble salt contaminant-free
antioxidant pigments performed as inhibitors against
corrosion of the silver/copper layer to result in
blocking of the corrosive decomposition of the metals.
Because of the water soluble compatible nature of the
soluble salt contaminant-free. pigments, an additional
performance feature was observed in relation to wet
W095I32092 ~ PGTIIJS94105836
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chemical plating of silver and copper metals- in an.
aqueous state. This aqueous plating application provides
ideal conditions for aqueous coatings which in turn
i
utilizes an amine as in the metal application process,
thus enabling the coating to "bite" the metal.
There~or~, compositions which contain a high level of
zinc cyanamide, up to 9~ on total formula, resulted in
good anti-corrosion protection. Additionally, when zinc
cyanamide is doped at a 2-50~ level--with nickel bis
cyanamide, cobalt bis-cyanamide, or lead cyanamide, the
corrosion retarding performance of the pigment system was
enhanced, and a synergistic effect was observed.
EBAMPLE III
The following alkyd resin formulation was prepared
by mixing the following components:
Ingredient Parts By Weiaht~s
Modified Alkyd Resin* 37.0
Melamine Resin 5.0
Ester Solvent 11.0
Alcohols 6.0
Aliphatic Solvent 3.0
Additives 20
Driers 0.8
Zinc Cyanamide (Wayne Pigment) 8.5
Red Oxide Pigment 8.0
Yellow Oxide Pigment 25
Inaredient Parts Bv Weights
Barium Sulfate 6.0
Extenders & Fillers 10.2
TOTAL 100.0
*MOdified Alkyd Resin Composition
Dehydrated Castor Oil
Linseed Oil
Phenolic Resin
Glycerin
Phthalic Anhydride
Aromatic Solvents
W095132092 2 PCT/US94/05836
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The coating was then applied to freshly silvered and
coppered glass and exposed to an infrared oven at 240°-
290°F for 3.5 minutes.
The coated mirror panels were then exposed to 20$
salt spray'urhich continued for-over 500. hours to comply
with Federal-Specification No. 33-M-4110. The panels
were then evaluated for edge creep on the sides, creepage
on the middle scribe, and for any spotting. The results
of the 500 hours salt spray test are as follows:
500 HOURS SALT SPRAY TEST RESULTS
DRY FILM THICKNESS OF COATINGS 1.5 TO 1.8 MILS
EDGE CREEP (mm) NONE
CREEPAGE ON MIDDLE SCRIBE NONE
SPOTTING NONE
In addition to the above tests, the following
industry standard tests were also performed. The results
are as follows:
24 Hours 5~ Ammonia Vapor - Pass
2 Hours FERRIC CHLORIDE - Pass
300 Hours Humidity - Pass
From the above results of the 500 hours Salt Spray
test, it will be noted that the edge creep test showed no
creep, there was no creepage on the middle scribe (a
standard industry test) and there was no spotting.
ESAMPLE IV
The following acrylic resin formulation was prepared
by mixing the following components:
Incrredient _ Pa_r_ts Bv WeicThts
Acrylic Resin* 37.0
Melamine Resin 5.0
Ester Solvent 11.0
Alcohols 6.0
WO 95!32092 2191 12 7 PCT/US94l05836
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Aliphatic Solvent 3.0
Additives 2.0
Zinc Cyanamide (Wayne Pigment) - 8.5
Red Oxide Pigment 8.0
Yellow Oxide Pigment 2.5
' Inaredient Parts Bv Weights
Barium Sulfate 6.0
Extenders & Fillers 11.2
TOTAL - _100. 0
*Obtained from Dock Resins Corporation under tradename TZ
55-2.
The coating was then applied by curtain coater on
top of freshly silvered and copperedglass. The glass
panels were then exposed to an infrared oven at 240°--
290°F for 3.5 minutes.
The coated mirror panels were then exposed to 20$
salt spray which continued for over 700 hours to comply
with Federal Specification No. 33-M-411C. The panels
were then evaluated for edge creep on the sides, creepage
on the middle scribe, and for any spotting of the mirror.
The results of the 700 hours salt spray test are as
follows:
700 HODRS SALT SPRAY TEST RESULTS
DRY FILM THICANESS OF COATINGS 1.5 TO 1.8 MILS
EDGE CREEP (mm) NONE
.CREEPAGE ON MIDDLE SCRIBE NONE
SPOTTING NONE
In addition to the above tests, the following
industry standard tests were also performed. The results
are as follows:
W095I32092 ~ PCTlUS94105836
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24 Hours 5~ Ammonia Vapor - Pass
2 Hours FERRIC CHLORIDE - Pass
480 Hours Humidity - Pass
The results of the 700 hour salt spray test show no
edge creep, no creepage,on the middle scribe and no
spotting.
The invention has been --described herein with
reference to preferred embodiments. However, as obvious
variations thereon will become apparent to those skilled
in the art, the invention is not to be considered as
limited thereto.
