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Патент USA US3096204

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United States
Patented July 2, 1963
lain crucible to a temperature of about 900° C.
fused composition is a sodium cobalto tungsto phosphate.
John L. Gallup Bloom?eld, N.J., assignor to Radio Cor
The vfused product was crushed in an iron mortar and
ground 24 hours in a pebble mill. The mill charge was:
poration of America, a corporation of Delaware
No Drawing. Filed Sept. 20, 1961, Ser. No. 139,377
5 Claims. (Cl. 106-—20)
Fused glass composition—1l3 grams, vglycerine,—37.8
This invention relates to glass marking inks and, more
particularly, to an improved opaque glass marking ink,
‘grams titanium dioxide, and additional glycerine in the
having a bluish white color, that may be fused to a glass
surface to produce a permanent opaque mark thereon.
In the marketing of articles such as electron vacuum
tubes having glass envelopes, there is applied to each
grams, and methanol-24 grams. This composition was
then mixed with 48.6 grams eutectic lead borate, 32.4
amount of 93.8 grams. The lead borate and titanium
dioxide were milled with the glycerine before adding to
the fused glass composition. Eutectic lead borate, as
used herein, is composed of 88% PhD and 12% B203
by weight.
The above mixture is applied to vacuum tubes .as fol
It is desirable that 15 lows: The mixture is spread upon a platen. A rubber
tube a number or symbol indicating the tube type and
also a trademark or brand name.
these marks be readily identi?able and also that they
should not rub off or deteriorate with long continued
usage. Previously, di?iculties have been experienced with
tube type markings in that they have tended to be some
thing less than permanent and it therefore becomes di?i
roller rolls back and forth across the platen and across
the face of a rubber stamp which is impressed upon suc
cessive glass surfaces. In this manner a controlled and
uniform quantity of marking ink is applied by the rubber
stamp to each glass surface it is desired to mark. The
glass surfaces are then carried by any suitable conveyor
apparatus past a gas ?ame of sufficient intensity to heat
necessary. Another di?iculty has been non-uniformity
the marked glass to approximately 550° C. This heating
of the color of the marks from one production batch to
oxidizes and drives off the vehicle of the ink mixture and
the next, thus detracting from the appearance.
A marking ink which has been used for vacuum tubes 25 fuses the other ingredients to the surface of the glass.
The combination of titanium dioxide and cobalt oxide
has comprised titanium dioxide and eutectic lead borate
produces a bluish white color regardless of whether the
in a vehicle such as ‘glycerine. The eutectic lead borate
.gas ?ames are oxidizing 'or reducing in nature.
fuses at relatively low temperature to glass, and titanium
The ?nal composition of the marks on the glass, ex
dioxide provides a desirable white color. The ink is sat
isfactory provided the gas ?ame commonly used to ?re 30 pressed, for convenience, as percentage by weight of
oxides in the various ingredients is as follows:
the ink and fuse it to the glass surface is su?iciently oxi
dizing in nature. However, if the gas ?ame is out of
Na2O ____
adjustment, as frequently happens in commercial pro
cult to determine the tube type when replacements are
duction over a period of time, insu?icient air supply to
the ?ame causes the flame to assume a yellowish color 35
and become slightly reducing in nature. When this hap
pens, the marking ink containing eutectic lead borate
tends to assume a color which is yellow to brown due to
partial reduction of the lead compound.
The discoloration not only detracts from the appear 40
ance of the mark but the mark is also more difficult to
read against certain backgrounds commonly found with
in vacuum tubes, such as that due to ?ashing of the metal
lic getter material within the tube.
One object of the present invention is to provide an
"no2 ____________________________________ __ 17.90
The above also represents the composition of the ink
solids (that is, with the vehicle omitted) prior to fusing
the marking ink to the tube surface. The composition
of the ink may be varied considerably. The solid ingre
dients may be varied substantially as follows:
improved glass marking ink less susceptible to change in
Percent by weight
color with changes in the oxidizing or reducing nature of
NazO _________________________________ __ 6 to 10
115 to 215
0.5 to 4
the gas ?ame used to ‘fuse the ink to the tube surface.
Another object of the invention is to provide an im
proved glass marking ink which is uniformly bluish white
in appearance.
A further object of the invention is to provide an im
proved glass marking ink having good legibility against
dark backgrounds.
The above and other objects are achieved in the mark
ing ink of the present invention which comprises, in addi
tion to titanium dioxide and lead 'borate mentioned above,
___ 10 to 20
___ 20 to 30
1 to 5
15 to 25
The amount of liquid vehicle may, of course, be varied
within rather wide limits depending upon the viscosity
of the ink which is desired and the viscosity depends in
turn on the method of application used. Vehicles other
than glycerine and methanol may also be used. In gen
cobalt oxide, and tungstic oxide. This ink has a bluish
the vehicle should be readily oxidizable, in addition
white appearance which is unvarying regardless of 60 eral,
to imparting proper ?ow and adherence properties in ac
whether the gas ?ames used in manufacturing are oxidiz
cordance with the mode of transfer to be used to apply
ing or reducing. The adherence properties are at least
the ink to the glass surface. Methods of application such
as good as inks previously used.
as spraying or stenciling may be used instead of the one
A preferred embodiment of the ink in accordance with
has been described.
the present invention will now be given and its method 65 which
The ink may, of course, be ?red on to the glass surface
of application explained.
by methods other than exposure to a gas ?ame, but the
A ?rst fused glass composition was prepared by making
advantages of the ink are especially noticeable with the
up a charge consisting of 51.8 weight percent
use of the gas ?ame method of ?ring.
The glass to which the ink is applied may be any of
the usual types used for laboratory apparatus or vacuum
43.5 weight percent W03, and 4.7 weight percent
tubes, and the like.
C00. This composition was fused by heating in a porce
further ingredients in the form of sodium phosphate,
What is claimed is:
‘1. A glass marking ink having solids, expressed as per
cent by weight oxides, Na2O: ‘6 to 10, PbO: 15 to 25,
5. A method of marking glass comprising applying to
a glass surface said markings in the form of an ink hav
ing solids, ‘expressed ‘as percent by weight oxides, Na2O:
C00: 0.5 to 4, TiO: 10 to 20, W03: 20 to 30, B203: 1 to
6 to 10, C00: 0.5 to 4, W03: 20 to 30 and P205: 15 to
5, and P2051
5 25, these ingredients being present as fused sodium co
2. A glass marking ink having solids expressed as per
balto tungsto phosphate powder; also PbO: '15 to 2'5 and
cent by Weight oxides, NagO' about 8.02, PbO about 2360,
B203: 1 -to 5 present as powdered eutectic lead borate;
TiO2: 10 to 20; and a liquid vehicle capable of being
C00 about 2.82, "E02 about 17.9, W03 about 26.1, B203
completely oxidized and volatilized at a temperature of
about 3.22, and P205 about 18.34.
3. Glass having markings of the composition, ex 10 about 550° C. and heating said ink on ‘said glass to a
temperature su?icient to fuse said ink solids to the glass
pressed ‘as percent by vWeight oxides, Na2O: 6 to 10, PbO:
and to drive off the vehicle.
15 to 25, C00: 0.5 to 4, T102: \10 to 20, W03: 20 "to 30,
B203: 1 to 5,
4. A glass marking ink having solids, expressed as
References Cited in the ?le of this patent
percent .by Weight oxide, NaZO: 6 to 10, C00: 0.5 to 4, 15
W03: 20 to 30 and P205: 15 to 25, these ingredients be
ing present as fused sodium cobalto tungsto phosphate
Max-Claudet _________ __ May 22, 1951
powder; also PbO: 15 to 25 and B203: '1 to 5 present as
Schurecht ____________ __ Dec. 22, 1953
powdered eutectic lead borate; TiO2: 10 to 20; and a
Gallup _______________ __ Nov. 8, M55
liquid vehicle capable of being completely oxidized and
volatilized at a temperature of about 550° C.
Foraker _____________ __ Nov. 20, 1956
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