U.S. patent application number 11/344950 was filed with the patent office on 2006-08-31 for method of decorating laminated glass.
This patent application is currently assigned to Ferro Corporation. Invention is credited to David C. Kapp, David L. McGowan, George E. Sakoske, Kimberly Ann Stewart, David M. Stotka.
Application Number | 20060191625 11/344950 |
Document ID | / |
Family ID | 36930970 |
Filed Date | 2006-08-31 |
United States Patent
Application |
20060191625 |
Kind Code |
A1 |
Kapp; David C. ; et
al. |
August 31, 2006 |
Method of decorating laminated glass
Abstract
A method of decorating laminated glass is disclosed. A pigment
package composition comprising a cross-linkable thermoset resin, a
crosslinker capable of crosslinking the thermoset resin, and a
pigment is applied to a glass substrate. The crosslinker and
thermoset resin are cured at a relatively low temperature (ca.
400.degree. F.). The use of an organic based pigment composition
allows use of thinner glass sheets than with traditional ceramic
enamel pigment compositions.
Inventors: |
Kapp; David C.; (Gibsonia,
PA) ; McGowan; David L.; (Washington, PA) ;
Sakoske; George E.; (Washington, PA) ; Stewart;
Kimberly Ann; (Bethel Park, PA) ; Stotka; David
M.; (Washington, PA) |
Correspondence
Address: |
RANKIN, HILL, PORTER & CLARK, LLP
925 EUCLID AVENUE, SUITE 700
CLEVELAND
OH
44115-1405
US
|
Assignee: |
Ferro Corporation
Cleveland
OH
|
Family ID: |
36930970 |
Appl. No.: |
11/344950 |
Filed: |
February 1, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60657020 |
Feb 28, 2005 |
|
|
|
Current U.S.
Class: |
156/99 ; 427/384;
427/407.1 |
Current CPC
Class: |
B32B 17/10247 20130101;
B44F 1/066 20130101; B32B 17/10697 20130101; B32B 17/10036
20130101; Y10T 428/24876 20150115; B32B 17/10779 20130101; B32B
17/10761 20130101; Y10T 428/24868 20150115 |
Class at
Publication: |
156/099 ;
427/384; 427/407.1 |
International
Class: |
B32B 17/10 20060101
B32B017/10 |
Claims
1. A method of forming a decorated glass structure comprising: a.
applying to a first glass substrate an organic pigment package
comprising, prior to curing, i. a crosslinkable thermoset resin,
ii. a crosslinker capable of crosslinking the thermoset resin, and
iii. a pigment; b. curing the crosslinker and the thermoset resin
to form a cured layer on the first substrate; c. stacking an acetal
layer and a second glass substrate onto the cured layer such that
the acetal and the cured layer lie between the first substrate and
a second glass substrate; and d. heating the first and second
stacked glass substrates to flow the acetal layer and effect
interpenetration of the acetal layer with the cured layer.
2. The method of claim 1 wherein, prior to curing, the crosslinker
and thermoset resin are present in an equivalence ratio of about
0.2 to about 1.2.
3. The method of claim 1 wherein, prior to curing, the crosslinker
and thermoset resin are present in an equivalence ratio of about
0.4 to about 0.9.
4. The method of claim 1 wherein, the crosslinker is a
melamine-formaldehyde, and the thermoset resin is a polyester and
wherein, prior to curing, the equivalence ratio of crosslinker to
polyester is about 0.45 to about 0.7.
5. The method of claim 1 wherein the thermoset resin is selected
from the group consisting of polyesters, urethanes, vinyl polymers,
acrylics, styrenes, polyolefins, polycarbonates, copolymers
thereof, and blends thereof.
6. The method of claim 1 wherein the crosslinker is selected from
the group consisting of: amines, amino resins, amido resins,
isocyanates, ureas, and dialdehydes.
7. The method of claim 6 wherein the crosslinker is selected from
the group consisting of melamines, acetoguanamines,
benzoguanamines, ureas, and combinations thereof.
8. The method of claim 6 wherein the crosslinker is selected from
the group consisting of: diphenylmethane diisocyanate, toluene
diisocyanate, hexamethylene diisocyanate, naphthalene diisocyanate,
methylene bis-cyclohexylisocyanate, isophorone diisocyanate, methyl
isocyanate, and polymethylene polyphenyl isocyanate.
9. The method of claim 6 wherein the crosslinker is selected from
the group consisting of fully alkylated melamine-formaldehyde
resins, partially alkylated melamine-formaldehyde resins, and high
imino melamine-formaldehyde resins.
10. The method of claim 1 wherein the pigment package further
comprises at least one of: a. a surfactant b. an adhesion promoter
c. an acid catalyst d. a light stabilizer e. a solvent, and f. a
rheology modifier.
11. The method of claim 1 wherein the pigment is selected from the
group consisting of azo dyes, cyanine dyes, pyridine dyes, dioxane
dyes, stilbene dyes, coumarin dyes, rhodamine dyes, oxazine dyes,
quinone dyes, anthraquinone dyes, and naphthalimide dyes,
quinacridone, phthalocyanine blue, phthalocyanine green, disazo
yellow, dibromoantoanthrone, dioxane violet,
1,4-bis(2-methylstyryl)benzene, and
trans-4,4'-diphenylstilbene.
12. The method of claim 1 wherein the pigment is selected from the
group consisting of iron pigments, cobalt pigments, cadmium
pigments, chromium pigments, copper mercury pigments, titanium
pigments, zinc pigments, lead pigments, magnesium pigments,
manganese pigments, and vanadium pigments.
13. The method of claim 1 wherein the pigment is selected from the
group consisting of: carbon black, titanium dioxide,
Fe.sub.2O.sub.3, Fe.sub.3O.sub.4, V.sub.2O.sub.5,
CoO--Al.sub.2O.sub.3--TiO.sub.2--Cr.sub.2O.sub.3, CeO.sub.2,
ZrO.sub.2, zinc oxide, magnesium ferrite, mercuric sulfide, cadmium
sulfoselenide, molybdenum chromate, zircon, copper chrome black,
iron nickel manganese chrome black, cobalt aluminate blue, zinc
iron chrome brown, and iron cobalt chrome.
14. The method of claim 1, wherein the pigment package comprises:
a. about 60 to about 85 wt % of thermoset resin+crosslinker, b.
about 5 to about 15 wt % of pigment, and c. further comprises about
3 to about 15 wt % of a solvent.
15. The method of claim 1 wherein the pigment package composition
comprises: a. about 60 to about 65 wt % thermoset resin, b. about 7
to about 13 wt % crosslinker, c. about 5 to about 10 wt % pigment,
d. about 0.1 to about 1 wt % surfactant, e. about 0.1 to about 3 wt
% rheological modifier, f. about 0.1 to about 1 wt % adhesion
promoter, g. about 0.1 to about 4% light stabilizers/blockers, h.
about 5 to about 15% solvent, and i. about 0.1 to about 2%
catalyst.
16. The method of claim 1 wherein the thermoset resin is a
polyester resin having a hydroxyl equivalent weight of about 200 to
about 1500.
17. The method of claim 1 wherein the decorated glass structure is
a flat piece of automotive glass.
18. The method of claim 1 wherein, prior to applying the organic
pigment package to the first glass substrate, the first and second
glass substrates are bent.
19. The method of claim 1 wherein applying to the first glass
substrate an organic pigment package comprises a technique selected
from the group consisting of screen printing, roll coating,
air-assisted spray, airless spray, inkjet, rotary screen print,
thermal transfer ribbon, electrostatic disk, and electrostatic
bell.
20. The method of claim 1 wherein the first and second glass
substrates are bent prior to applying the pigment composition and
wherein the pigment composition is applied to the first glass
substrate by ink jet printing.
Description
[0001] This application claims priority to commonly owned copending
U.S. Ser. No. 60/657,020, entitled "METHOD OF DECORATING LAMINATED
GLASS" filed 28 Feb. 2005, which is hereby incorporated herein by
reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of Invention
[0003] The present invention relates to the decoration of glass
substrates with organically based pigment compositions that are
free of ceramic enamels, particularly for use with automotive
glass.
[0004] 2. Description of Related Art
[0005] Decoration of laminated safety glass by conventional ceramic
enamels is constrained by the minimum thickness needed to prevent
warping of the decorated sheet during the firing process. Prior art
methods not only required thicker glass panels to withstand the
heat of firing an enamel color/pigment package, but the enamel
based pigment composition had to be applied prior to a press-bend
or other heating operation. For two reasons, then, it was possible
to get a rippled or warped glass pane: (1) because the glass
ceramic pigment layer was bent along with the (double) glass layers
and (2) because the panels were thick enough to withstand enamel
firing. Prior art decoration methods could not employ
screen-printing to apply the glass ceramic enamel to an already
bent glass, because screen printing requires a flat surface, and
because the ceramic based enamel would require a heating operation
to sinter and fuse the enamel which could further cause warping or
shape distortion.
SUMMARY OF THE INVENTION
[0006] Instead of using a ceramic enamel frit containing a pigment
to effect the coloration of a windshield or the application of an
opaque band around a windshield, the invention uses a thermoset
resin (crosslinking resin) and a curing agent. The present
invention permits a broader array of pigment application
techniques, including ink jet printing. Further, because ink jet
printing can be done on a curved surface, it is possible to print
the decoration on the second or third (i.e., interior) surfaces
after bending the glass.
[0007] Decoration with organic inks and/or coatings takes place at
temperatures too low to distort the glass, permitting the use of
thinner glass sheets and giving lighter laminated panels with
superior clarity. Such laminations are useful in applications such
as flat vehicle glass, curved windshields, marine transparencies,
and safety spandrels.
[0008] Organic decorations can be applied to the second or third
(interior) surfaces of a laminated glass panel, and interpenetrate
with a laminating film such as polyvinyl butyral. This
interpenetrating effect maintains an acceptable level of bonding
between the laminating resin film and the glass sheets. The organic
decoration can be in ink or coating form and may be applied by the
traditional methods such as screen printing, direct or reverse roll
coating, air-assisted or airless spray, digital inkjet, rotary
screen print, thermal transfer ribbon, electrostatic disk, and
electrostatic bell. Cure can be achieved by thermal initiated
crosslinking, ultraviolet or electron beam photopolymerization, air
catalyzed self-condensation, two-component condensation, or the
like. The controlling requirement is that the final cured film be
sufficiently interpenetrable with the laminating film so that a
bond of adequate strength is maintained between the lamination and
glass sheets. In the case of automotive obscuration bands,
decorative and protective effects should also be achieved. Applying
the organic decoration to the interior surface of a laminated glass
panel protects the decorated surface form mechanical and/or
chemical damage that may occur during manufacture or service.
[0009] The invention involves a method of forming a decorated glass
structure comprising: applying to a first glass substrate an
organic pigment package comprising, prior to curing, a
crosslinkable thermoset resin, a crosslinker capable of
crosslinking the thermoset resin, and a pigment; curing the
crosslinker and the thermoset resin to form a cured layer on the
first substrate; stacking an acetal layer and a second glass
substrate onto the cured layer such that the acetal and the cured
layer lie between the first substrate and a second glass substrate;
and heating the first and second stacked glass substrates to flow
the acetal layer and effect interpenetration of the acetal layer
with the cured layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a graph showing the pull strength in pounds
required to delaminate a PVB layer from a cured polyester melamine
layer in relation to the equivalence ratio between melamine
crosslinker and polyester.
[0011] FIG. 2 is a graph showing the pull strength in pounds
required to delaminate a PVB layer from a cured polyester melamine
layer in relation to the equivalence ratio between
epoxy-dicyandiamide crosslinker and polyester.
[0012] FIG. 3 is a graph showing the pull strength in pounds
required to delaminate a PVB layer from a cured polyester melamine
layer in relation to the equivalence ratio between hexamethylene
diisocyanate crosslinker and polyester.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The method of forming a decorated glass structure involves a
pigment package composition, which comprises a crosslinkable
thermoset resin, a crosslinker and a pigment. However, the
composition typically further comprises solvents, catalysts,
surfactants, light stabilizers, UV blockers, and adhesion
promoters. Each ingredient is discussed in turn.
[0014] Thermoset Resin. Broadly, the green pigment package
composition, prior to curing, comprises about 50 to about 95%
thermoset resin, preferably about 55 to about 90%, more preferably
about 60 to about 75% and most preferably about 60 to about 65%.
All percentages herein are by weight. The thermoset resin may be
any thermoplastic polymer having crosslinkable functional sites.
Suitable types of thermoset resins include polyesters, urethanes,
vinyl polymers, acrylics, styrenes, aromatic polyolefins, aliphatic
polyolefins, polycarbonates, copolymers thereof, and blends
thereof. The preferred thermoset resins are polyesters. Polyester
resins useful herein include those having a hydroxyl equivalent
weight of about 200 to about 1500, preferably about 450 to about
650. Suitable polyester resins include several from Etna Products
Co. of Chagrin Falls, Ohio, including SCD.RTM.-1040, SCD-1060,
SCD-16602, SCD-18263, SCD-19071 TX, and SCD-6000. Other polyester
resins suitable for use in this invention include Cargill's 66-6613
resin; Chempol.RTM. 11-2339 and Chempol.RTM. 11-3369 resin by Cook
Composites and Polymers; Kelsol.RTM. 301, a trademark for a
polyester from Reichhold Co as well as AROPLAZ.RTM. 6025-Z-70 resin
by Reichhold which is believed to be the product of the
condensation of a 67:33 by weight mixture of isophthalic acid and
adipic acid with a molar excess of propylene glycol to give an OH
value of about 62(70% solids), K-Flex.RTM. 188 from King
Industries, and Resydrol.RTM. VAN 6098, a trademark for a polyester
from Solutia Co. Details of polyesters suitable for use in the
present invention are further provided in U.S. Pat. No. 5,326,820,
and highly cyclic-aliphatic polyesters described in U.S. Pat. No.
5,262,494, both of which patents are hereby incorporated by
reference. A preferred polyester is Etna's SCD-6000, which is an
oil-free thermoset polyester resin, having a hydroxyl equivalent
weight of 529.
[0015] Precursors of polyester resins can also be included in the
inventive compositions. The polyester resins are made by a
condensation polymerization reaction, usually with heat in the
presence of a catalyst, or a mixture of a polybasic acid and a
polyhydric alcohol (polyol). Exemplary acids to form the alkyd
resin or reactive polyester include adipic acid, glutaric acid,
succinic acid, azelaic acid, sebacic acid, terephthalic acid, and
phthalic anhydride and the like. Examples of polybasic alcohols
include ethylene glycol, propylene glycol, diethylene glycol,
dipropylene glycol, glycerine, butylene glycol,
2,2-dimethyl-1,3-propanediol, trimethylol propane,
1,4-cyclohexanedimethanol, pentaerythritol, trimethylolethane and
the like.
[0016] Crosslinkers. The crosslinking resin forms crosslinks with
the pigment-bearing thermoset resin. The density of the crosslinks
therebetween determines the strength of the final laminated glass
panel. The pigment package composition herein comprises about 5 to
about 20 wt % of one or more crosslinkers, preferably about 8 to
about 15 wt % and preferably about 10 to about 12 wt %. The noted
percentages are prior to curing.
[0017] In prior art formulations the use of an organic-based
pigment composition (i.e., thermoset resin+crosslinker+pigment)
tends to disrupt the adhesion between a glass layer and a PVB layer
in a safety glass windshield. The inventors have discovered a
method and composition that minimizes disruption in the adhesion of
one glass layer to another through the PVB layer, which normally
occurs when an organic coating is interposed between the glass and
the acetal. The method promotes the interpenetration of the PVB
layer into the pigment-bearing organic coating without compromising
the strength of the laminated glass panel.
[0018] Crosslinking agents such as amines, amino resins, amido
resins, isocyanates, ureas and dialdehydes are suitable for use in
the present invention. Combinations of crosslinkers are also
suitable. For example, aminoplasts are oligomers that are the
reaction products of aldehydes, with amines or amides. The amines
and amides are exemplified by melamine, urea, and benzoguanamine.
Exemplary aldehydes include formaldehyde and glyoxal. Exemplary
aminoplasts include melamine-formaldehyde resins, melamine-glyoxal
resins, urea-formaldehyde resins, urea-glyoxal resins,
carbamide-formaldehyde resins, benzoguanamine-formaldehyde resins,
and glycol-urea resins.
[0019] While urea and melamine with formaldehyde and glyoxal are
the basic constituents of the crosslinker/thermoset package, but
melamine may be partly or completely replaced by benzoguanamine
and/or acetoguanamine. Melamine-formaldehyde and urea-formaldehyde
are the preferred amino resins, and combinations thereof may be
used also. Further examples of preferred amino resins include those
based on ethylene urea, for example, a resin based on
dimethylolethylene urea is prepared from urea, ethylene diamine,
and formaldehyde; propylene urea-formaldehyde, a resin prepared
from urea, 1,3-diamino-propane and formaldehyde; triazone resin
made from urea, formaldehyde and a primary aliphatic amine such as
hydroxyethylamine; uron resins, mixtures of a minor amount of
melamine resin and uron (predominantly N,N'-bismethoxymethyl)uron
plus about 25% methylated urea formaldehyde; melamine-formaldehyde
resins including the dimethyl ether of trimethylolmelamine; and
methylol carbamate resins.
[0020] It is sometimes advantageous to employ precursors of
aminoplasts such as hexamethylol melamine, dimethylol urea, and
their etherified forms, i.e., modified with alkanols having from
one to four carbon atoms. Hexamethoxymethyl melamine and
tetramethoxy glycoluril exemplify said etherified forms. Thus, a
wide variety of commercially available aminoplasts and their
precursors can be used for crosslinking with the thermoset resins
of the invention.
[0021] In general, highly alkylated and partially alkylated
melamine-formaldehyde resins are useful. Particularly preferred are
the amino crosslinking agents sold by Cytec Industries, Inc, of
West Patterson, N.J., under the trademarks Cymel.RTM.,
Melurac.RTM., and Urac.RTM.. Cytec's melamine urea formaldehyde
resins include Melurac.RTM. 450HF, Melurac 4004, and Melurac 5005;
urea formaldehyde resins such as Urac.RTM. 185 are similarly
suitable. In particular, highly alkylated melamine-formaldehyde
resins such as hexamethoxymethylmelamine, available as Cymel 301,
Cymel 303, and Cymel 385 (methoxymethyl methylol melamine) are
useful, further, melamine formaldehyde resins Cymel 401, Cymel
405LD, Cymel 406, Cymel 412, Cymel 481, Cymel 483, Cymel WE-1025D,
and Cymel 9800 may be used. Partially alkylated
melamine-formaldehyde resins are also suitable. Most preferred is
Cymel 303.
[0022] While single package formulas possess handling and
processing advantages, two-component formulations may also be used.
In a two-component formulation, the thermoset resin/pigment
component and the crosslinker component are supplied separately and
are mixed immediately prior to application. In this case, the
crosslinker component is typically one that will react with the
thermoset resin component at low temperature or room temperature.
The advantage to this type of formulation is that a cured
composition can be achieved with little or no external heating. The
disadvantage is that the mixture possesses a relatively short
working lifetime, making storage and re-use of the mixture
impractical. Crosslinkers of this type are typically unblocked
isocyanates such toluene diisocyanate and hexamethylene
1,6-diisocyanate, such as Coronate HXLV available from Nippon
Polyurethane Company, Ltd.
[0023] While not being bound theory, it is believed that the
strength of a decorated glass laminate is related to the degree of
interpenetration between the polymeric network formed by the
condensation of the thermoset resin with the crosslinker, and the
polymeric network of the acetal (PVB) sheet in the laminate. The
molar relationship between crosslinker and thermoset resin is known
as the equivalence ratio. First, the molar amounts of crosslinker
and thermoset resin are each individually expressed as the ratio of
functional groups to molecular weight. These are the equivalent
weights of the crosslinker and the thermoset resin. Multiplying the
weight of each resin by its respective equivalent weight gives the
number of equivalents in the formulation. The ratio of (equivalents
of crosslinker) to (equivalents of thermoset resin) is the
equivalence ratio. Prior to curing, the equivalence ratio of
crosslinker to thermoset resin may be about 0.2 to 1.2. More
preferably, this ratio is about 0.4 to about 0.9. More preferably
still the ratio is about 0.45 to about 0.7. Most preferably, a
pigment package composition comprises a melamine-formaldehyde
crosslinker and a polyester thermoset resin wherein the equivalence
ratio of crosslinker to polyester is about 0.45 to about 0.7.
[0024] The curing of hydroxyl-functional polyesters with
aminoplasts can be effected over a wide range of cure conditions.
For example cure can be effected in only several seconds at very
high temperatures, e.g., about 650.degree. C. (1200.degree. F.).
Use of lower temperatures, e.g., about 100-120.degree. C. (about
210-250.degree. F.), can require about 40-60 minutes. To cure the
thermoset resin-crosslinker systems contemplated herein, a
temperature as high as about 540-650.degree. C. (about
1000-1200.degree. F.) can be used to effect curing in as little as
about 60-80 seconds, for example, about 70 seconds at about
620.degree. C. (about 1150.degree. F.). However, in accordance with
the principles of the invention, such as minimizing glass thickness
and warpage during firing and cure, a maximum glass temperature
during cure of about 400.degree. F. (about 205.degree. C.) is
preferred, for example about a 20 minute cure.
[0025] The aminoplast oligomer compound of the composition may be a
urethane-amine adduct, prepared by reaction of an amine with a
polyisocyanate. The polyisocyanate may be a simple polyisocyanate
such as toluene diisocyanate, diphenylmethane-4,4-diisocyanate, or
hexamethylene diisocyanate, or may be prepared by reaction of a
polyol and a polyisocyanate, such as naphthalene di-isocyanate or
methyl isocyanate. Further isocyanates include
methylene-bis-cyclohexyl isocyanate, isophorone diisocyanate, and
polymethylene polyphenyl isocyanate. Examples of suitable polyol
components include polyester polyols, polyether polyols and
polyester polyether block copolymers.
[0026] Pigment. The pigment may be essentially any organic or
inorganic colorant, pigment, or dye that can be used to impart
color or opacity to a glass structure. While a variety of pigment
loads is possible, typically the pigment package composition of the
present invention comprises about 2 to about 20 wt % of one or more
pigments, preferably about 5 to about 15 wt % and more preferably
about 7 to about 10 wt %. Black, dark, or opacifying pigments may
be used to create an opaque sun blocking band around the periphery
of a windshield, either for aesthetic purposes, or for protective
purposes, or both. A typical protective purpose is to protect from
sunlight degradation the adhesive that holds the windshield to the
frame of the car.
[0027] Conventional pigments including carbon blacks, iron
pigments, cobalt pigments, cadmium pigments, chromium pigments,
copper mercury pigments, titanium pigments, zinc pigments, lead
pigments, magnesium pigments, manganese pigments, and vanadium
pigments are suitable. Further suitable inorganic pigments include
carbon black, TiO.sub.2, Fe.sub.2O.sub.3, Fe.sub.3O.sub.4,
V.sub.2O.sub.5, CoO--Al.sub.2O.sub.3--TiO.sub.2--Cr.sub.2O.sub.3,
CoO--Al.sub.2O.sub.3, CeO.sub.2, ZrO.sub.2, ZnO, magnesium ferrite,
mercuric sulfide, cadmium sulfoselenide, molybdenum chromate,
zircon, copper chrome black, iron nickel manganese chrome black,
cobalt aluminate blue, zinc iron chrome brown, iron cobalt chrome,
chromium oxide green, chrome yellow, and moly-orange.
[0028] Also envisioned herein are pigment package compositions that
result in glass decorated structures, which, when recycled, do not
cause subsequently formed glass products to be discolored. In
particular, in such an embodiment it is advantageous to avoid
pigments or other ingredients which include cobalt, chromium,
copper, nickel, vanadium and zinc.
[0029] Further, there has been an effort in recent years to
eliminate certain heavy metals from industrial production lines and
from waste streams. To that end, also envisioned are pigment
package compositions, which are devoid of pigments and other
ingredients containing lead, cadmium and mercury. With respect to
the avoidance of both discolored recycled products and of heavy
metals, such embodiments do not contain any intentionally added
cobalt, chromium, copper, nickel, vanadium, zinc, lead, cadmium or
mercury.
[0030] Organic dyes may be suitable as pigments. Useful dyes
include cyanine dyes; phthalocyanine dyes, such as phthalocyanine
blue and phthalocyanine green; azo dyes, such as disazo yellow;
polycyclic quinone dyes, such as anthraquinone or
dibromoanthraquinone; dioxane dyes, such as dioxane violet;
stilbene dyes, coumarin dyes, naphthalimide dyes, pyridine dyes,
rhodamine dyes, and oxazine dyes.
[0031] Stilbene dyes are exemplified by
1,4-bis(2-methylstyryl)benzene, trans-4,4'-diphenylstilbene.
Coumarin dyes are exemplified by 7-hydroxy-4-methylcoumarin;
2,3,5,6-1H,4H-tetrahydro-8-trifluoromethylquinorizino(9,9a,1-gh)coumarin;
3-(2'-benzothiazolyl)-7-diethylaminocoumarin; and
3-(2'-benzilimidazolyl)-7-N,N-diethylaminocoumarin. Naphthalimide
dyes are are exemplified by basic yellow 51, solvent yellow 11, and
solvent yellow 116. Rhodamine dyes are exemplified by
2-(6-(diethylamino)-3-(diethylimino)-3H-xanthene-9-yl)benzenecarboxylic
acid, rhodamine B, and rhodamine 6 G. Cyanine dyes are exemplified
by 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostilyl-)-4H-pyran.
Pyridine dyes are exemplified by
1-ethyl-2-(4-(p-dimethylaminophenyl)-1,3-butadienyl)-pyridium-perchlorate-
.
[0032] Solvent. Solvents include glycols such as ethylene glycol,
propylene glycol and hexylene glycol; alpha- or beta-terpineol;
higher boiling alcohols such as Dowanol.RTM. (diethylene glycol
monoethyl ether); butyl Carbitol.RTM. (diethylene glycol monobutyl
ether); dibutyl Carbitol.RTM. (diethylene glycol dibutyl ether);
butyl Carbitol.RTM. acetate (diethylene glycol monobutyl ether
acetate); Texanol.RTM. (2,2,4-trimethyl-1,3-pentanediol
monoisobutyrate), as well as other alcohol esters, kerosene, and
dibutyl phthalate. Products sold under the Texanol.RTM. trademark
are available from Eastman Chemical Company, Kingsport, Tenn.;
those sold under the Dowanol.RTM. and Carbitol.RTM. trademarks are
available from Dow Chemical Co., Midland, Mich.
[0033] Dispersing Surfactant. A dispersing surfactant assists in
pigment wetting, when an insoluble particulate inorganic pigment is
used. A dispersing surfactant typically contains a block copolymer
with pigment affinic groups. For example, surfactants sold under
the Disperbyk.RTM. and Byk.RTM. trademarks by Byk Chemie of Wesel,
Germany, such as Disperbyk 162 and 163, which are solutions of high
molecular weight block copolymers with pigment affinic groups, and
a blend of solvents (xylene, butylacetate and
methoxypropylacetate). Disperbyk 162 has these solvents in a 3/1/1
ratio, while the ratio in Disperbyk 163 is 4/2/5. Disperbyk 140 is
a solution of alkyl-ammonium salt of an acidic polymer in a
methoxypropylacetate solvent.
[0034] Rheological Modifier. A rheological modifier is used to
adjust the viscosity of the green pigment package composition. A
variety of rheological modifiers may be used, including those sold
under the Byk.RTM., Disperplast.RTM., and Viscobyk.RTM. trademarks,
available from Byk Chemie. They include, for example, the BYK 400
series, such as BYK 411 and BYK 420, (modified urea solutions); the
BYK W-900 series, (pigment wetting and dispersing additives); the
Disperplast series, (pigment wetting and dispersing additives for
plastisols and organosols); and the Viscobyk series, (viscosity
depressants for plastisols and organosols).
[0035] Flow aid. A flow aid is an additive used to control the
viscosity and rheology of a pigment composition, which affects the
flow properties of liquid systems in a controlled and predictable
way. Rheology modifiers are generally considered as being either
pseudoplastic or thixotropic in nature. Suitable surfactants herein
include those sold commercially under the Additol.RTM.,
Multiflow.RTM., and Modaflow.RTM. trademarks by UCB Surface
Specialties of Smyrna, Ga. For example, Additol VXW 6388, Additol
VXW 6360, Additol VXL 4930, Additol XL 425, Additol XW 395,
Modaflow AQ 3000, Modaflow AQ 3025, Modaflow Resin, and Multiflow
Resin.
[0036] Adhesion promoter. Adhesion promoting polymers are used to
improve the compatibility between a polymer and a filler. Suitable
adhesion promoters include those sold by GE Silicones of Wilton,
Conn. under the Silquest.RTM., CoatOSil.RTM., NXT.RTM.,
XL-Pearl.TM. and Silcat.RTM. trademarks. Examples include the
following product numbers, sold under the Silquest.RTM. trademark:
A1101,A1102,A1126,A1128,A1130,A1230,A1310,A162,A174,A178,A187,
A2120. For example, Silquest.RTM. A-187 is (3-glycidoxypropyl)
trimethoxysilane, which is an epoxysilane adhesion promoter. The
inventors herein have found that aromatic epoxies crosslinked with
amines or amides produced unacceptable results. Silanes sold by
Degussa AG of Dusseldorf, Germany, under the Dynasylan.RTM.
trademark are also suitable. Most preferred herein is Silquest
A187.
[0037] Acid Catalyst. Acidic catalysts may be used to control cure
parameters of the polyester with an aminoplast resin by lowering
the required temperature or raising the reaction rate or both. The
amount and type of catalyst used depends on the thermoset resin and
the crosslinker chosen. However, in general, the pigment package
composition herein comprises about 0.1 to about 2.0 wt % of
catalyst, preferably 0.2 to about 1.5% and more preferably 0.7 to
about 1.4%. When it is desirable to reduce the rate of cure at
ambient storage temperatures, the acidic catalyst may be blocked
with an amine or other suitable blocking agent. Volatile amines,
which may escape from the curing film when the catalyst is
unblocked by heat, are suitable for this purpose. The curing may
also be retarded by the addition of free amines such as
triethanolamine. Also, the potential reaction of the acidic
catalyst with the hydroxyl groups on the polyester may be blocked
by the addition of relatively non-volatile alcohols such as butanol
and 2-ethylhexanol; such alcohols also provide viscosity stability
in the package. They inhibit the reaction of the polyester with the
aminoplast.
[0038] Acid catalysts commercially available from King Industries
under the NACURE.RTM. and K-CURE.RTM. trademarks. For example, an
amine-blocked dinonyl naphthalenesulfonic acid sold as NACURE 1557
is an example of the blocked acid catalyst contemplated for use in
the aminoplast curing of the composition of this invention. Another
suitable catalyst is NACURE 5225, which is an amine-blocked dodecyl
benzenesulfonic acid. Others include the following product numbers,
all sold under the NACURE trademark: 3525, 3527, 1323, 1557, 5528,
5925. Most preferred is NACURE 5225.
[0039] Stabilizers. Light or UV stabilizers are classified
according to their mode of action: UV blockers--that act by
shielding the polymer from ultraviolet light; or hindered amine
light stabilizers (HALS)--that act by scavenging the radical
intermediates formed in the photo-oxidation process. The
compositions of the invention comprise about 0.1 to about 2 wt % of
a light stabilizer, preferably about 0.5 to about 1.5%, and further
comprise about 0.1 to about 4 wt % of a UV blocker, preferably
about 1 to about 3%.
[0040] Light stabilizers and UV blockers sold under the
Irgafos.RTM., Irganox.RTM., Irgastab.RTM., Uvitex.RTM., and
Tinuvin.RTM. trademarks by from Ciba Specialty Chemicals,
Tarrytown, N.Y., may be used, including product numbers 292 HP,
384-2, 400, 405, 411L, 5050, 5055, 5060, 5011, all using the
Tinuvin trademark. Suitable UV blocking agents include Norbloc 7966
(2-(2'hydroxy-5'methacryloxyethylphenyl)-2H-benzotriazole); Tinuvin
123 (bis-(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl)ester);
Tinuvin 99 (3-(2H-benzotriazole-2-yl)5-(1,1-dimethyl
ethyl)-4-hydroxybenzenepropanoic acid, C7-9-branched alkyl esters)
Tinuvin 171 (2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methyl-phenol).
Products sold under the Norbloc.RTM. trademark are available from
Janssen Pharmaceutica of Beerse, Belgium.
[0041] Suitable hindered amine light stabilizers (HALS) are sold by
the Clariant Corporation, Charlotte, N.C., under the Hostavin.RTM.
trademark, including Hostavin 845, Hostavin N20, Hostavin N24,
Hostavin N30, Hostavin N391, Hostavin PR31, Hostavin ARO8, and
Hostavin PR25. HALS are extremely efficient stabilizers against
light-induced degradation of most polymers. They do not absorb UV
radiation, but act to inhibit degradation of the polymer, thus
extending its durability. Significant levels of stabilization are
achieved at relatively low concentrations. The high efficiency and
longevity of HALS are due to a cyclic process wherein the HALS are
regenerated rather than consumed during the stabilization process.
They also protect polymers from thermal degradation and can be used
as thermal stabilizers.
[0042] Applications. The pigment package composition of the present
invention may be used to color or decorate a variety of glass
substrates, including automotive, architectural, construction, home
appliance, and beverage glass industries, e.g., car windshields and
other automotive glass, residential and commercial windows, ceramic
cooktops and beverage bottles. For example, the ceramic enamel
composition may be used to form a border, which is colored and/or
UV resistant, around the periphery of a pane of automotive glass.
If a conductive constituent such as copper or silver is added to
the inventive pigment package composition, it may be used to form a
functional coating, such as a heated glass windshield.
[0043] Further, the pigment package composition may be used as an
impact resistive or dispersive layer in bullet-proof glass such as
PVB-interlayered polycarbonate windshields or glass panes. In such
an embodiment, it may be advantageous to provide the pigment
package composition without a coloring pigment, wherein the
thermoset resin and crosslinker serve solely to strengthen the
polycarbonate laminate.
[0044] Envisioned herein is a method of forming a decorated glass
structure comprising applying to a first glass substrate an organic
pigment package comprising, prior to curing: a cross linkable
thermoset resin, a crosslinker capable of crosslinking the
thermoset resin, and a pigment. The crosslinker and the thermoset
resin are cured to form a cured layer on the first substrate. An
acetal layer and a second glass substrate are stacked onto the
first substrate such that the acetal and the cured layer lie
between the first and second glass substrates. The stacked glass
substrates are heated to flow the acetal layer and effect
interpenetration of the acetal layer with the cured layer.
[0045] Example 1. The inventive pigment package composition was
formulated according to Table 1, which follows, with percentages by
weight. TABLE-US-00001 TABLE 1 Formulation for Organic Pigment
Package Composition SCD-6000 Polyester resin 62.8% Cymel 303
Crosslinking resin 10.5% Degussa Special #4 black pigment 8.3%
Propylene glycol solvent 9.9% Nacure 5225 catalyst 0.7% Disperbyk
163 dispersing surfactant 0.5% Modaflow surfactant flow aid 1.3%
Byk 410 Rheological modifier 1.1% Tinuvin 1130 UV Blocker 2.0%
Tinuvin 292 light stabilizer 1.0% Silquest A-187 silane adhesion
promoter 1.5%
[0046] From the ingredients of Table 1, the polyester and
crosslinking resins are preblended using a high-speed stirrer, the
black pigment is added and the mixture is stirred to form a
relatively homogenous paste. The paste is then passed over a
three-roll mill to disperse the pigment to a reading of at least
6.0 on a Hegeman fineness-of-grind gauge (Byk-Gardner, Silver
Spring Md.), in accordance with ASTM D1210, D333, and D1316. The
remaining ingredients are then blended in under stirring. The
resulting composition is screen printed as a 3''.times.3'' (7.6
cm.times.7.6 cm) square onto a 4''.times.5'' (10.2 cm.times.12.7
cm) soda lime glass panel using a 200 mesh polyester screen. The
printed panel is then cured in a 205.degree. C. (400 .degree. F.)
oven for twenty minutes.
[0047] The strength of the film is tested as follows. A
polyvinylbutyral (PVB) film is cut into a square 2 inches (58 mm)
on a side. A slit about 1.5 cm long is made in the center of the
PVB square, parallel to a side. Two mild steel "L" brackets
commonly available at any home improvement store serve as the
attachment point for a spring scale. The brackets have holes at
each end. The two "L" brackets are placed back-to-back and the PVB
square is slipped down over the upright arms until the film is
lying against the horizontal arms. The bracket and film assembly is
then placed in the middle of the cured print and the entire unit is
put in a 205.degree. C. oven for seven minutes to melt the acetal
film onto the surface of the organic print.
[0048] After melting in the oven, the brackets are now affixed to
the organic print by a thick, transparent PVB layer. This assembly
is then placed in freezer for a minimum of one hour. Freezing
reduces the flexibility of the acetal so that upon performance of
the pull test, none of the upward force is mitigated by internal
stretching of the PVB.
[0049] After removing the assembly from the freezer, a spring scale
is hooked into the hole at the top of the vertical bracket, and
pulled vertically with a single, continuous motion. Care should be
taken that the sample does not have time to warm up and the PVB
regain elasticity. A clamp or other holder should be used to secure
the glass plate in the event that the glass breaks during the test.
When sufficient force is applied, the acetal/bracket assembly will
break loose from the coated glass plate. The force needed to break
the bond between the acetal and the coating can be read off the
spring scale.
[0050] As shown in FIG. 1 the pull-strength maximum (maximum PVB
pull rating of 100 pounds) of the formulation of Example 1 was
produced at an equivalence ratio of 0.474. Markedly poorer adhesion
was observed above and below this level. The other formulations
varied the relative amounts of melamine and polyester (in FIG. 1
from left to right, the melamine content increased) but the initial
weight of (melamine+polyester) remained constant, as did the
amounts of the other ingredients.
[0051] Without being bound by theory, the effect appears to be a
balance between intra-polymer integrity of the ink and
inter-polymer penetration between the acetal film and the ink film.
At the lower ratios, solvent resistance is negligible, and the film
appears to tear when the acetal is removed. At higher ratios,
solvent resistance is very good and the acetal releases from the
ink film cleanly, with no disruption of the ink. At the maximum,
solvent resistance is marginal, and in some areas, the acetal
leaves some ink remaining on the glass while in other areas the ink
is entirely removed. The inventors interpret this behavior to mean
that the acetal penetrates the ink film at the lowest equivalence
ratios, but the ink film is so poorly crosslinked that the acetal
pull test causes intra-polymer tearing and a longitudinal scission
of the film. At higher equivalence ratios the crosslink density is
high enough to inhibit inter-polymer penetration so the acetal
remains segregated on top of the ink film, and releases cleanly
when pulled.
[0052] A second set of tests used an epoxy-dicyandiamide system, in
Example 2. FIG. 2 shows much lower pull strengths from an
equivalence ratio of 0.48 to 0.96. At equivalence ratios above
0.48, the acetal film released cleanly during the pull test,
indicating essentially no inter-polymer penetration. At an
equivalence ratio of 0.48, the ink film ripped apart, which can be
interpreted as penetration by the acetal into the ink film, but
poor intra-polymer integrity within the ink film. The inventors
believe that the epoxy-dicyandiamide system resists inter-polymer
penetration by the acetal until the crosslink density is reduced to
a level where the integrity of the ink film is compromised.
[0053] Solvent resistance as measured by acetone double rubs is
consistent with the above interpretations for both systems. A
cotton cloth is dampened in acetone and rubbed back and forth by
hand across the cured polyester melamine coating layer. One "back
and forth" cycle is a "double rub." The polyester-melamine system
resists over 50 double rubs at equivalence ratios of 0.875 and
higher. At ratios of 0.474 and 0.685, the solvent resistance drops
to 20 double rubs, while at the lower equivalence ratios the film
was easily removed with a single rub. The epoxy-dicyandiamide
system resists over 50 double rubs at all ratios except the lowest,
where again, the resistance drops to a single rub.
[0054] In Example 3, a third set of tests involved a two component
system where component "A" was represented by the polyester
formulation of Example 1, however in place of Cymel 303 was used
Coronate HXLV, (hexamethylene1,6-diisocyanate crosslinker). As was
the case with melamine crosslinkers, the adhesion of the film to
PVB increased as the ratio of NCO to OH decreased, as shown in FIG.
3.
[0055] Unlike melamine, the PVB adhesion continued to increase as
crosslinker ratio decreased, with the strongest bond measured at
the lowest ratio. At this level, the cured film was not of
practical use, because its degree of internal cohesion was so low
that the ink film formed visible gaps when the acetal film shrank
in place as it was melted against the inked surface. While the
overall trend is similar to that seen with melamine, overall the
strength of the acetal bond is lower to the isocyanate crosslinked
film.
[0056] Additional advantages and modifications will readily occur
to those skilled in the art. Therefore, the invention in its
broader aspects is not limited to the specific details and
illustrative example shown and described herein. Accordingly,
various modifications may be made without departing from the spirit
or scope of the general invention concept as defined by the
appended claims and their equivalents.
* * * * *