Decorative glass enamels

Details Decorative glass enamels Decorative glass enamels

1999-10-27

2002-02-12

Sample, David R (Department: 1755)

Compositions: ceramic

Ceramic compositions

Glass compositions, compositions containing glass other than...

C501S018000, C501S019000, C501S020000, C501S025000, C501S026000, C501S032000, C501S058000, C501S059000, C501S063000, C501S064000, C501S065000, C501S066000, C501S067000, C501S069000, C501S070000, C501S078000, C501S079000

Reexamination Certificate

active

06346493

ABSTRACT:

FIELD OF INVENTION
The present invention provides a new and improved lead-free and cadmium-free glass enamel composition for use in decorating glass articles such as, for example, architectural glass plate.
BACKGROUND OF THE INVENTION
Various lead-free and cadmium-free glass enamel compositions are known in the prior art. Examples include the compositions described in Ruderer, et al., U.S. Pat. No. 5,306,674; Heitmann, et al., U.S. Pat. No. 5,707,909; Clifford, U.S. Pat. No. 5,304,516; Klimas, et al., U.S. Pat. No. 4,970,178; Anquetil, et al., U.S. Pat. No. 5,350,718; and Anquetil, U.S. Pat. No. 5,674,789. Such enamel compositions are often applied in the form of a paste to a glass surface to be enameled. The paste usually contains finely divided particles of one or more glassy materials, commonly called “glass frits,” one or more colorants or pigments, fillers, and a vehicle. After application of the paste by screen printing or other techniques, the composition is fired to volatilize and/or thermally decompose and drive off the vehicle, fuse the glass frits, pigments, and fillers together, and bond the enamel to the glass surface.
For many applications, a lead-free and cadmium-free glass enamel composition must display good flow at traditional glass enamel firing temperatures (typically from about 550° C. to about 720° C.). Upon firing, such enamel compositions preferably produce an enamel finish that displays no cracking, good chemical resistance, and good weatherability. Several prior art glass enamel compositions can be used to produce enamels exhibiting these properties, but there is a need for a lead-free and cadmium-free glass enamel composition that exhibits improved color values upon firing in addition to these properties.
SUMMARY OF INVENTION
The present invention provides a new and improved lead-free and cadmium-free glass enamel composition that displays good flow at traditional glass enamel firing temperatures and upon firing produces an enamel finish that displays no cracking, good chemical resistance, good weatherability, and improved color values. The glass enamel composition of the present invention comprises a glass component, an oxidizer, a pigment system, and optional fillers. The glass component preferably comprises one or more glass frits comprising from about 28% to about 60% by weight SiO
2
, from about 9% to about 21% by weight B
2
O
3
, up to about 15% by weight Na
2
O , up to about 13% by weight K
2
O , up to about 6% by weight Li
2
O, up to about 6% by weight Al
2
O
3
, up to about 25% by weight TiO
2
, from about 5% to about 22% by weight ZnO, up to about 20% by weight Nb
2
O
5
, up to about 9% by weight Bi
2
O
3
, up to about 11% by weight ZrO
2
, up to about 12% by weight BaO, up to about 8% by weight SrO, up to about 5% by weight CaO, up to about 2% by weight MgO, up to about 5% weight LnO
x
, where “Ln” is an element selected from the Lanthanide Series and is most preferably an element selected from the group consisting of La, Ce, Pr, and Nd, up to about 6% by weight Sb
2
O
3
, and up to about 6% by weight fluorine. The presence of the oxidizer in the composition, which can be included as part of the glass component, as a separately added material, or both, significantly improves the color values of the fired enamel as compared to enamels formed using similar glass enamel compositions having no oxidizer present. When the oxidizer is included as part of the glass component, the oxidizer preferably comprises Sb
2
O
3
, NH
4
NO
3
, or K
2
S
2
O
8
. Alternatively, the oxidizer can be included as part of the glass component as one or more low temperature decomposing nitrates such as NaNO
3
and KNO
3
, persulfates such as (NH
4
)
2
S
2
O
8
and K
2
SO
4
, peroxides such as BaO
2
and ZnO
2
, antimonates such as NaSbO
3
, CaSb
2
O
6
and sulfates such as Na
2
SO
4
, and for colored glasses, as one or more chromates and/or permanganates. When the oxidizer is included as a separately added material, the oxidizer preferably comprises one or more compounds selected from the group consisting of peroxides such as barium peroxide, zinc peroxide, and hydrogen peroxide, and persulfates such as ammonium persulfate, and potassium persulfate. A broad range of pigment systems can be used in the invention, including white pigments systems based upon TiO
2
, CeO
2
, ZrO
2
, and zircon, and colored pigment systems conventionally used to produce colors such as blue, brown, and black.
The foregoing and other features of the invention are hereinafter more fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the present invention may be employed.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention provides a new and useful lead-free and cadmium-free glass enamel composition that displays good flow at traditional glass enamel firing temperatures. Upon firing, the composition of the present invention forms an enamel finish having good chemical resistance, no cracking, good weatherability, and improved color values. As noted above, a need exists in the glass enamel industry for a lead-free and cadmium-free glass enamel composition that exhibits these properties.
The glass enamel composition of the present invention is lead-free and cadmium-free. As used throughout this specification in the claims below, the terms “lead-free” and “cadmium-free” mean that no lead, or PbO, cadmium, or CdO, have been intentionally added to the composition, and that the composition comprises less than about 0.5% by weight PbO or CdO.
The glass enamel composition of the present invention comprises a glass component, an oxidizer, a pigment system, and optional fillers. The glass enamel composition according to the present invention is preferably mixed with a suitable vehicle or carrier which allows the enamel composition to be applied to a section of glass in a convenient form such as, for example, a slurry, a paste, or a thermoplastic pellet.
The glass component of the glass enamel composition of the present invention preferably comprises one or more glass frits. Preferably, the glass component of the present invention displays the following composition:
Percent by
Preferred Percent
Component
Weight
by Weight
SiO
2
28-60 
31-55
B
2
O
3
9-21
11-19
Na
2
O
0-15
 6-11
K
2
O
0-13
0-5
Li
2
O
0-6 
0-4
Al
2
O
3
0-6 
0-4
TiO
2
0-25
0-9
ZnO
5-22
11-21
Nb
2
O
5
0-20
 0-17
Bi
2
O
3
0-9 
0-5
ZrO
2
0-11
0-7
BaO
0-12
0-5
SrO
0-8 
0-5
CaO
0-5 
0-3
MgO
0-2 
0-1
LnO
x
(*)
0-5 
0-3
Sb
2
O
3
0-6 
0.25-6  
F
0-6 
0-3
(*) where “Ln” is an element selected from the Lanthanide Series and is most preferably an element selected from the group consisting of La, Ce, Pr, and Nd.
The glass frits employed in the present invention may be prepared utilizing conventional glass melting techniques, which are well known in the art. Typically, a 500 g. batch is smelted at around 1250° C.±100° C. for about 30-60 minutes and the molten glass is then converted to frit by water quenching or using water-cooled rollers. It will be appreciated that production of the glass frits used in the invention is conventional, and that any of the various techniques well known to those skilled in the art can be employed.
As noted, the glass enamel composition according to the present invention also comprises an oxidizer. The oxidizer contributes to the improved color values of the enamel upon firing. The oxidizer may be included in the glass component, or it may be included in the enamel composition as a separately added material. Alternatively, the oxidizer may be included both in the glass component and as a separately added material. In all cases, the oxidizer should be stable at room temperatures in the presence of the other components that comprise the composition.
When the oxidizer is included in the glass component, it preferably comprises one or more

Affiliated with

Also associated with

Rating

Decorative glass enamels does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Decorative glass enamels, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Decorative glass enamels will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2943204