Note: Descriptions are shown in the official language in which they were submitted.
~ '7
38021
RGW
LEAD-FREE AND CADMIUM-FREE GLASS FRIT COMPOSITIONS
FOR GLAZING, ENAMELING AND DECORATING
The present invention relates to lead-free and cadmium-
free glass frit compositions which possess desirable properties
and characteristics which enable them to be used for glazing,
enameling and for decorating a variety of food service ware;
glassware such as tumblers, chinaware and the like. The
compositions of this invention may also find use in selected
applications such as microelectronic encapsulation, and for the
10 ¦formation of a light diffusing layer on a glass surface. The
decorating glazes and glass compositions of the present invention
have the advantage of containing no lead or cadmium components.
Most oE today's commercially available food service
ware is marketed with varying degrees of external ornamentation
and decoration. Manufacturers of such ware have long recognized
that decorated glassware has improved customer appeal and will
sell better than undecorated ware- As a result, much effort over
the years has gone into research and development relating to
l decorating compositions for all types of dinnerware, tableware,
20 ¦and food service ware in general.
Il Decorating compositions generally fall into two
¦¦categories; glazes and enamels. The glazes are usually thought
¦¦of as clear glasses, while enamels are glazes which contain a
!!coloring material such as a pigment. In actual usage, the glazes
25 ¦Iand enamels are used in a finely divided form called a "frit",
Iwhich is selectively applied to the surfaces of the glassware,
j!glass-ceramic ware, chinaware and ceramic ware in accordance with
the intended decorative or ornamental pattern. Any of several
Idecorating techniques known in the industry can be used to
30 ~lachieve this result. Typically, the frit is in the form of a
ll
` ~2~L2970
~paste ~hich consists ~f the finely divided glaze or enamel
composition plus a vehicle. After application to the ware by
silk screen or other technique, the ware is heated or fired to
fuse the frit, volatilize the vehicle or medium and firmly bond
the decoration to the surface of the ware.
According to the present state of the art, there are a
variety of decorating compositions available which are used in
the decorating of glassware, chinaware and the like, to produce
selected patterns and ornamentation. Often times, these
available compositions contain lead and/or cadmium oxides. Lead
oxide was previously used in these compositions to lower the ¦ ~
melting point of the frit so that the frit could be fused onto
the surface of the ware at as low a temperature as possible to
avoid thermal deformation of the ware. Cadmium oxide has been
used in the past as a colorant in certain frits. Certain States
of the Union have now enacted legislation prohibiting the use of
cadmium and lead in glazes used for decorating of ylassware and
chinaware on the ground that these materials are allegedly toxic
and that young children would be particularly susceptible to the
allegedly toxic affects of these components. The present
invention therefore eliminates risks associated with having
allegedly toxic materials present in glazing and decorating
¦compositions. Further, the present invention avoids the risk of
¦¦possible recall of decorated ware in particular states which may
25 ¦¦in the future enact legislation prohibiting the use of cadmium
and/or lead oxides in decorating compositions.
The present invention further eliminates the need for
~testing the content of decorative glazes and glass compositions
llto determine if the level of alleged toxic materials has been
30 1I kept to the required minimum. Thus, the cost of compliance
testing is overcome.
- 2 -
~,
;970
I 1,
The decorative glaze compositions of the present
invention contain no lead and cadmium oxides, t'nereby enabling ~,
the glass manufacturer to recover sales in those states which
require or mandate zero lead or cadmium content in glassware
sold in those states intended for drinking purposes or in
chinaware that coms into contact with food.
The glasses of the present invention can have
substantially lower densities than lead containing glasses. For
example, (2.6842 vs. 4.5837). One pound of the new ~lasses has
a higher volume than ~he previously commercially used decorating
materials. The volume of glass available for printing controls
the number of decorated glass pieces. For example, 1 pound of
lead glass will print approximately 500 glass pieces of a
specific design. In contrast, a typical lead-free glass of the
invention in the amount of 1 pound will print approximately 850
pieces o~ the same design. This was arrived at through the
following calculation:
Yolume per pound of material
lead glass - Density 4.5837 g/cc
lead-free glass - Density 2.6842 g/cc
Lead: Volumel= Wt = 1 lb. = 453-6~m = 98 96
Uensity 4.5837 4.5837
No Lead: Volume2 - 453-6 = 168.99 = 170 ml
.6842
1¦ Ratio 500 pieces x 1.7 = 850 pieces
; The present invention also provides a potential for
251 lower raw material costs because of the avoidance of the need to
use the relatively expensive lead and cadmium components. For
~¦ the same reason, the presen~ invention has a potential for
lowering the cost of color pigments.
!
t
~l ' 3
I i
I
~ 1297~7
This is illustratd by the f~llowing: ¦
The glass decorating glazes have minimum of two
components:
A - Glass (= flux) and
~ B - Color Pigment (= stain)
The B part pigments are identical or similar in both
lead and lead-free glasses to achieve the selected colors. The
lead-free glass A part raw materials without tin oxide are
cheaper than lead glasses. For example, a typical glass of the
present invention could be 20% to 30% less expensive, as compared
to the cost of one pound of lead containing glass.
A number of advantages characterize the present
invention including the fact that the decorating compositions
described herein meet the requirements of good decorating
glasses, protective glazes and enamels without using allegedly
toxic materials. It is important, particularly for the
decoration of glassware and chinaware which is used in a home or
restaurants, that the decorating compositions have sufficient
alkali resistance and hardness so that they will be able to be
exposed for many years to dishwashing cycles without serious
degradation which would cause an unattractive deterioration of
the decorated ware.
The present invention provides many compositions which
¦¦can be harder and there~ore more scratch resistant than
25ljcompositions generally known in the art today As a result,
there are included among the compositions of the present
invention those which are especially suited as top coats for
chinaware. It has been determined by applicants that the
lipigmented glasses of the present invention are less sensitive
30 1l to furnace atmosphere than are compositions known in the art
especially those which contain certain cadmium pigments such as
- 4 -
" I ~21Z9~O
cadmium sulfide and cadmium selenide ~CdS and CdSe, respectively)
which are sensitive to oxidation. Depending on the particular
formulations and components, the present invention provides
compositions which, in general, have enhanced properties such as
lower expansion, high hardness, high chemical resistance,
particularly alkali resistance, and a sufficiently longer glassy
range in relation to other lead-free glasses such as zinc oxide
containing compositions.
In accordance with one feature of the present invention
there are provided alumino-borosilicate compositions which may be ¦
used for glass and chinaware decorations and hybrid
microelectronic applications. In general, the compositions in ' ~
accordance with this feature of the present invention are based
on the A12O3 - B2O3 - SiO2 system, wherein there is also present
lithia, Li2o, and at least one other component selected from the
group consisting of 2rO2~ SnO2, CeO2, La2O3, CaO, SrO, BaO, Na2O,
ZrF4, NaF and 3NaF.AlF3.
In anothex aspect of the invention, there are provided
compositions which are free of added aluminum values in the form
of A12O3 and which are defined as containing substantial amounts
of lanthanum oxide expressed as La2O3. These compositions are
based on the B2O3 - SiO2 - ZrO2 - La2O3 system and also contain
lithia, Li2O.
Characteriæed by good chemical resistance, the glasses
of the present invention also have good gloss and smoothness. In
¦addition, they have generally hard surfaces without containing
allegedly toxic materials. Among the glasses of the present
invention are those which may be fired in the temperature range
l of 580C to 630C at the normal rate and holding time, using
30 ¦conventional glassware and chinaware decorating lehrs.
il In the industry today, it is important that the
¦!compositions used for the decoration of glassware and chinaware
¦ have the characteristics described below.
,i -- S --
2~ 7~ ~
J,
The decorative compositions should be capa-ble of being
fired in the firing range of 580C to 630C. It is generally
desired that the holding time at the peak temperature be in the
range of 7 to 11 minu~es, with the hea~ing rate of 14C to 15C
per minute. The time to reach the peak temperature should range
to about 40 minutes ~ 10 minutes.
The compositions used for decorating should be capable
of being fired to a smooth, shiny layer without "running out" of
the printed area and at the same time being capable of forming
Çine lines with no bleeding, that is, the patterns produced on
the glassware should be clear and crisp and should not be fuzzy, I
blurred or indistinct~ ¦
It is desirable that the decorated glassware and
chinaware be capable of withs~anding dishwasher cycles,
preferably in the presence of rather strong detergent~ for a
range of 5 to 20 years. In addi~ion, the decorated material on
the glassware should not be removed or susceptible to attack by
the acids normally encountered in fruit juices.
For applications such as art glass, electronic purposes
and light diffusing coating the glasses do not need to possess
acid and/or alkali resistance.
Finally, the decorated material should not exhibit any
cracks after firing or develop any cracks in actual usage.
These properties, features and characteristics can be
determined by quantitative test data as well as by observation.
Therefore, a specific decorating composition can be evaluated to
determine whether it will be satisfactory for commercial
i purposes. For example, decorated glassware can be subjected to
l dishwasher cycling tests. By subjecting the decorated ware to ',
301 attack using 5% sodium pyrophosphate at 60C for 8 hours measured
at 2-hour intervals, accelerated laboratory tests can be carried
out to predict dishwasher resistance.
- 6 -
I I ,
~2g7~ ~
For the fruit juice test, generally two acids are usied
to determine the susceptibility of decorated glassware to
attack. The first test is a 2% citric acid for 30 minutes at
l room temperature and the second test is a 4% acetic acid for
¦ 24 hours at room temperature.
Smoothness and the characteristics of the fired print
definition can be predicted by a test which is called the "flow
number" test. The flow number is calculated by the ratio of the
measured width to the measured height of a fired sample pellet
of the decorating composition. The pellet of the decorating
composition is placed on a glass surface and the height of the
pellet above the glass surface is measured. The measured width
is the width of the pellet surface in contact with the glass
surface. Good samples will have a flow number between 1 to 1.2.
Numbers lower than 1 suggest lower glass adhesion. Numbers
higher than 1.3 suggest a poor definition with run down from
printed lines, that is, excessive bleeding of the paste.
Any fracturing or crac~ing tendencies in the decorated
material are related to differences in the thermal contractions
of the substrate glass or chinaware (tumbler or dinnerware) and
the decorating glass from the peak temperature down to room
temperature. These differences can be determined by the residual
stress in the tumbler glass caused by the contracting decorating
l¦glass. For example, the test can be determined by using a sample !
251lcube with 2.5 mm edge which is fired in contact with the base
~glass with the desired heating rate, holding time and temperature
and also cooling rate. The induced stress is measured by
¦polarized light retardation in accordance with procedures known
l¦in the art. t
30 il The conversion is measured by using a test sample with
l¦a thickness of about 100 mils. The thickness of the fired
il !
1 1 - 7 - '
ll l
,
, ,
~ 297a~ !
decorating layer is about 1.2 to 2.3 mils. The measured stress
¦¦values shown in the Table 1 which is set forth below are about 4
¦to 6 times greater than the expected stress values for fired
screen printed decorating layers as determined experimentally.
The test specimens were observed for cracking and the
observations were recorded in Table 1. It is apparent that the
pellet stresses up to approximately 1600 psi did not show cracks
in the thin layers which range from 1.2 to 2.3 mils.
The above-mentioned test techniques and procedures
are well known and documented in the field of glass technology.
It should be noted that the compositions of the present
invention can be used in conventional screen printing techniques
~hich are well known and understood in the art and do not form a
~art of this invention. Any such conventional screen printing
methods can be used for purposes of the invention.
In its broadest aspects, the present invention relates
to compositions based on a borosilicate glass system represented
~y the following listed components in the indicated weight
percent ranges expressed on an oxide basis: ¦
20 ¦ComponentWeiqht Percent
23 0 - 30
l B203 16 - 32
-ll SiO2 11 - 40
LiO2 4 - 12
25 l~he balance consisting of other compatible glass making
components to be described in further detail below.
In addition to these listed ingredients, which form the
l~ase glass, the system generally further contains one or more of
IZrO2, SnO2, CeO2, La203, CaO, SrO, BaO, Na20, ZrF4, NaF, and
!BNaF.AlF3.
1. ~
, I - 8 - ,
. ~ .
lZlZ97~ 1
ll It will be noted that these compositions are zinc
¦free. Whereas zinc has been used in decorating compositions and
has been found useful in achieving low viscosity in glass at
specific temperatures, zinc is listed as not desirable in
Idrinking water and should be, limited to no more tha about 5
¦mg/l.
More particularly, the glass compositions of the
present invention contain the following components expressed in
oxides in weight percent, based on the total composition.
Component Weiqht Percent
23 0 - 30
B203 16 - 32
SiO2 11 - 40
Li20 4 - 12
Zr2 O - 18
SnO2 0 - 20
CeO2 0 - 2
La23 0 - 15
CaO O - 16
20 1 SrO O - 13
BaO 7
Na20 0 - 3.5
F O - 2.6
¦and wherein
~1 ~ SnO2+CaO 2 - 23
25 I ~ zrO2+La203 2 - 23
~ ZrO2+~1203 0 - 26.5
¦, ~ CaO+SrO+BaO O - 19.25
¦¦ Table 1 shows representative compositions of the
Ipresent invention which have been found to materially improve the
30~'characteristics of decorated glassware and chinaware.
_ 9 _
1212g70
! These compositions include those which have outstanding
¦alkali resistance, and acceptable stress layers. Some
l¦compositions which have relatively high stresses which may cause
¦Isome cracks can be remedied by including as fillers an
5 ¦ appropriate amount of a low expansion ceramic such as beta- I
eurcryptite. Som~ color pigments also function to low~r the
stress as is known in the art. Clays can be used; as well as
mullite; quartz and the like.
In a further feature of the present invention, it has
10 been found that the follswing compositions are especially well
suited for the purposes descrlbed herein:
Component Weiqht Percent
A123 19-20
B203 28-30
SiO2 11-15
LiO2 4-8
l Zr2 4~7 5
1I SnO2 6-19
I La23 0_0~5
20 ¦~ CaO 0-4
SrO 0-13
BaO 7
!
Na20 0-0 . 25
F 0-1 . 5 `
Compositions falling within the above stated parameters
, I .
25 " have good fiber softening point data and develop a compressive
stress, or low tensile stress, when tested for stress
characteristics.
With the above preferred compositions of the invention,
it may be noted that when SnO2 is present in an amount of greater
30- than 10% by weight, the amount of SrO should be less than 10~;
-- 10 --
lZlZ97~ 1
I ',
conversely when SrO exceeds 10% then the amount of SnO2 should be
less than 10%. Also within the parameters stated above, the sum
of CaO + BaO ~ SrO should be in the range of 6-21 with a maximum
of 7% BaO and 5% CaO, with the added provision that there must
~always be either BaO or CaO present. Preferred compositions
coming within the above ranges are those shown in Table 1,
examples 5, 13, 14, 22 and 230
Some compositions of the invention are colorless and
therefore may be used as a barrier or top coating onto
conventional decorating compositionS which may contain lead and
cadmium in order to prevent or retard lead and cadmium release I ~
from the decorated surfaces.
The following examples, with the exception of example
15, illustrate the invention without being intended to limit it
in any way. Example 15 is intended for purposes of comparison.
The compositions were recalculated to the standard normal oxide
percentages. In compositions 1, 5-9, 16, cryolite (3NaF.AlF3)
was used, in examples 5, 7, 8, 12-14, and 18, ZrF4 was added; in
¦¦compositions 3, 4 and 15 zircon was added; in compositions 4, 11,
15 and 17 NaF was used. Therefore, in the respective examples,
zircon was changed to ZrO2 and SiO2 percentages, NaF into F and
Na20 percentages, ZrF4 into F and ZrO2 percentages and cryolite
¦linto F, Na20 and A1203 percentages. In this table, the symbols
"A" and "C" indicate acetic acid and citric acid respectively.
-- 1 1 -- I
ll i
lZ1~97U
I ~
I ~ ~J oo o o o o Ln o o o o Ln o o
I ... ...... ... . o ~ ~
c~l ~ ~ ~ O a~ o ~o o o o ~ Ln ~ o o ~ o o
Ln ~ ~ Z
,~ o o ~o ,-~
,~ ,~ ~oo o o o o o o o ~ o
~1 . . .. . , . . . . . ~,o ,1 ~o ~
oo ~ooo co oo ~o n n o o ~ o o ~ c~l Ln o ~ i
C~l ~ ~ Ln ~ C`~ ~ ~
~ o o O E~ ''
I ~ ~ C~o o o o o o o ~ L
n o o~ o Ln o o o ~ o o o o 1~ n o
Ln ~ ~ Z
n nLn L
1~ n C~ o o o o o o o 1~ C~l o
cr~ o oo Ln o ~ O ~ O O ~ ~i ~ i~ a~ i
l ~ C~ ~ ~ Ln ~ ~ ~
I~ ~o ~n ~ Ln n ~ ~ E~ i
o ooo o Ln 1~ ~i C~l Li-) o C~ Ln ~ oo o
C~l . . . . . ... . . . . . . ~o " o O~
oo~ O oO ~ ~ O O ~ O Ln O ~ n
C~ C~ ~ ~ Ln
~I
o~ nc~l n
u~~ ~ ~ o o ~ o c~ n o c~ oo ~ o o
Z
O ~~ ~ o oo i~ C~l ~o c~ o o ~o o n o ~ ~ ~ ~o o
E~ ~ n ~ ~ z
H
O ~ Ln Ln Ln n
~ ~ n o C~ Ln i~ o C~ ~n Ln C~ n o
~o l ~ l ~o co i~ C~l Ln C~l o o i-- o Ln o o Ln ~ o
~, n ~ ~ Z
¢ co ~ Ln n o C~l Ln ~ o
~ ~ oo i~ ~ n i-- ~ C~l n o ~ oo c~ o i-~
~ ~ o
nl ~ ~ ~ o~ oo i~ ~ ~ ~ o o ~ o Lr~ o o ~ ~ Ln o
. ~ ~ Ln ~ ~ Z
I oo ~ c~
I o ~ ~ o o o o o o o o o i-- oo o
. . . . . . . . . Ln ~ o cq
~ ~ O ~ O C~ O ~ O ~0 o o ~ ~ Ln I~
E~ ~1 ~ c~l ~ ,1
~ l~ o~ ~ o o o o o o o o o o ~ o
i. . . . . . . . . . . ~ o Ln
l~l ~ n oo o c~ ~o ~o Ln C~l ~ o ~o o ~ ~ ooo ~ o o
,, Ln ~ ~ æ
.
oo o~ O E~ I
~ I~ ~ o o o o o o o ~ Ln
C~l l 0 C~ ~ o ~ D Ln O O O O ~') O O O ~0 ~ O
.~ Ln ~ ~ Z
I~O ~) i-- O O O O O O o O O ~ O
I. . . . . . . , . ~ , I o ~q ;
~ ~ l 0 -- ~ ~ ~ ~o co Ln o o C~ ~o o o co c~l Ln l~ au
i ~ ~ ~ ~ Ln
i
) ¢
~co ~ ¢
i~
f~ ~ 1 0
. ~1 U U rl u~
IO ¢ ¢ ¢ ~ ~
I i~; rl ~ ~ o
U~ O ~ O C~ l O O U~
. u~ u~ O c~ O c~l o ~ o o C~l o o o C~ n y
; U~ O O O ~ ~I C~l-rl rl ~-I f~ 0 ~i 4 t~
1~ 1~ 1~ Ei ¢ a~ 1 Z ~ v~ o i'-f t~
O ~/ J~
,
, - 12 -
~ 97
U~
oo U~
~ ~ ,, I
C~l C~l ~ i
U~
C~
~i
o
~,
U~ ~ U~
Z o~
H ~I C~l ~1
H
U~ U~ Ul
~ r~
a~
O
U~ C~
~ C~
C~ oo ~ U~
. ~ C~
~ ~ U~ LO ~
i~l
oo U~
o U~
¦
l 1,
i
C`l ~ i.
I
I o
~ ~ ~ i
o o q
o C~ +
+~ +~ ~ +
l O O O O
.
. U~
! W W W W
- 13 - '
~1 i
~2~ 7~
o ,,
r~ ~ ~ o o o o o o c~
~ o o
~ ¦ ~ o o 1-- oo co o o .. ~ c~ o o o o o c~ o
C~ 1 ~ ~ ~ ~ Z ,,
I ;t ~r) ~ U'l C~ ~
C~ O O O O O O O O O O U~ ,
D il O ~ ~ ~D U) I~ O O ~) ~1 ~ O O 1~ ~ O
I c~ o- ~1 Z ~,
~,
O
O Ut ~ O O O O O O O O O C~l Lt~ !
. . . . . . . . . . . .L,'~ o ~
r` ~ o o ~ u~ ~ ~O o o ~ ~ ~ o o ~ C~l o
r~o~o
~ ~ ~ O O O O O O O O O
.~S) ~ O oo o~o O ~ l ~ O O 1
a~ o o oo u ~ o o u~
.. . . . . . . . . . ~
I L~~ ~O 00 000 ~D O O O O O1~ 00 ~ C`l O
~ ,, ~ æ ' -
_~~ I~ oo ~ E-~ i
~ ~ ~ O O O O O O O O U~
U~ ~ I ~ ~ ~ O 00 OD Lr. ~ O O O O ~D O O O ~ 1--
~1 ~ ~ c~
H
H
OC~ ~D ~ O O O O U~ O O U~ ~ O
Plo~l ~ ~ ~ o oo co `;t ~ o o o co o o o ~ l o
~ ~1 1 ~I c~l c~l ,1 ,_1 u-l ~ ~I Z
O
cl~ ~ O O
U~ U~ o~ ~ O O O O O O O U~ U~ oo O
;~i ~ o `D O O ~ C`~ 00 a) i'
C~ I ~
.
~` o C~
o ~ 1-- r~ o o o o o o ~ o oo
. ....... .. . . . . . . oo o
~D I ~ ~ I~ oo ~ ~O ~ u~ O ~ O ~O O O ~ c~
I ~ ~1 c~l ~ ~ u~ ~ c~
i~
oo ~ o O O O E~ I
~ ~ ~ O `D ~D O u~
u~ I ~ ~ O O C~ O C~ O ~ o o ~ c~
~1 ~ ~ c~ c~l ~ ~ u~
!
I ~ o o
c~ ~ ~ o o o o u~ o o L~
. ~ I ~ ~ ~ O ~ ~ ~ ~D ~ O O O O 1~ 0 0 ~ O O
Z
I o~ o o
I ~ ~ ~ o o o o ~ o o o U~ ~ o
l . . . . . . . . . . . . ~ o oo
i ~ I ~ ~o ~ o CO oo ~ ~ U~ o o ~ ~ o o ~ ~ . o o
I .,~ ~ ~ Z
i
I
¢~,
i
, . a ~
I ~ rl rl O ~ ~ i
l., ~ c~ ~ .~ tn j
Io ¢ ¢ ¢ ~ ~
Z ~ ~ ~ O
cq 0 u~ U~ O ~ O ~ C~ O O o7 ~n
. co u~ o ~ o c~l O O O ~I
i tq O O 0 ~ 3
O ~ a~ z F~ O i~
- 14 -
121Z9~S~
C~
I
l ,, ~ ~ .
o ~ ~ ~
!j
o~
C~
~ U~
C~l O ~ ~D 1` !
~ C~
zi o~
O ~
~ U~U')
~3 ~ Ll~
. ~1 Cl ~ I
I~ I
i
l U~
~ li
l , U~
. o~
I~
~ O
I ~ ~ ~
O o
. ~ ~ ~ o
I + ~$ ~ ,
C~
I o o o o
I
l U~
, W W W W
- 15 -
.
~ ~ooo ~ 97~
,~ ~ u~ u~ O O O O O O O r~
~ co ~ ~ o o o o~ o o ~ o r~ ~ o
~ Z
c~ ~ ~ o o o o ~ o o o o ~ E~
~ol ~ ~ ~ ~ u~ co oo ~ o o ~D ~ ~ O ~ O ~ Z
~1 ~ c~
,~ ~ ,~ o o o o o ~ o
U~ ~ Ul o ~ C~ o o o o C`l o o o o o oo ~ o
~ or~
r~ o o o o o o ~ u~ I
~1 ~ ~ ~ o ~ oo o o o o u~ o o o ~ o ~ . r~ a
~, C~l ~ ~ ~ ~ ~ ~i
o E~
oo o o o o o o o o o ~ o
~1 ~ o ~ o o ~ c~ o o ~ o o o z
~ ~ ~ ~ ~D ~ ~
.
u~ O r~
C~ ~ o o o o o o o o C`~ ~
I ~ ~J ~ o ~J oo o ~ ~ o ~ oo o o ~ o 1~ U~ o
r~ ~I c~ ~ oo Z
U~
c~l ~ c~
_, o ~ I~ o o o o o o ~ o ~ o
o ~ cr~ o ~ o ~ u~ o o ~ o ~ c~ o
~I c~ 1 ~ Z
U~
o
H ~ C~l
E-l oo c~l 1~ 0 0 0 0 0 0 0 0 1~
H l ~ O ~ CS~ O u~ ~1 O Lr~ ~ O O t` O 1~ ~ O O
O ~ c~ D Z
i~ c~ ~ ~ O E~
cn ~ ~ ~D O O O O O O ~ O
u~ 'l o ~ ~ c, o oo n o c~i o u~ o o o o o cr~ o o
~ ~ Z
oo In o c~
oo u) oo o o o o o o u~ o
o~l o oo C~ O C~ 1~ 0 ~ O O ~ ~ O O O O ~ ~ O
~1 ~1 ~ ~ ~ I Z
a~
i~ c~ ~ 0 0 E~
I~ ~ ~ o o o o o o ~ o
1--1 ~ ~ Q ~ O c~i o O u~ ~ o O O O ~ ~ O
~ ~ ~ 1 Z
~ O E~ !
oo ~ oo o o o o o o ~ o
~1 '~ ~ o r o ~ o o Ll~ ~ o o o o o ,~ o
~D ~ ~ Z
I ~ c~
,~ C~ o o o o o o o~ U '.
u~l o 1~ c~l o O r o ~D O O ~ ~ O O O O O~ r-i O
C~
i
¢
l to o~ ¢
I ~ ~ ~i 0~
. ,~
Z ¢ ~ ¢ ~ U~, I
~ q o ~ o c~ o o ~ u~ I
a~ cq ~ o~ o C~l o C~J O O O O C~l O O O C~
O~ O O O ~ ~I C~l-rl r~ 3 a.l C)
,~ ~0 ¢ a~ o ~-~
- 16 -
~ 97
I
l l
o~oo
' ~~~1
~
~ ,~ ~ ~ oo
~ ~ .
C~
U~ ~D oo u~ U) ,
~æ
o
3 ~oo
. ~
I
l l
l I
Il o~ o~ ~q I
.! o c~l ~+
~ o
~1 + ~
, o o o o
" U~
W
- 17 -
-~ lZl;~970
From the foregoing tables, it will be seen that for
¦those compositions containing aluminum oxide the components
¦included the following in the indicated weight percent ranges
based on oxides:
Component Weight Percent
A123 15-30
B203 16-32
Li20 4-12
SiO2 8-40
Zr2 3-6.5
SnO2 0-20
CeO2 0-2
La203 0-6
CaO 0-16
SrO 0-13
BaO 0-7
Na20 0-3.5
F 0-3
~herein from example 1 to 23: ¦
~SnO2+CaO is 9 to 23
~ZrO2+La203 is 3 to 7
rO2~Al203 is 23 to 26.5%
~CaO+SrO~BaO is 7 to 21%
Il I
ll Within the above ranges were those compositions which
25 liexhibited no cracks in the tests. These compositions contain the
following ingredients:
Weiqht_Percent
I' A1203 15-30
30 ll B203 16-32
Il Li20 4-12
I~ l
Il - 18 - I
, . .
'! ~
~z~z9~o
Li20 4-12
SiO2 10-40
Zn2 4-6.5
SnO2 0-20
CeO2 0-2
La23 0-6
CaO 0-16
. SrO 0-13
BaO 0-7
Na20 0-3 -
F 0-1.5
wherein generally:
SnO2~CaOis 10 to 23%
zrO2+La203 is 4 to 6.5~
zrO2~Al2o3 is 24 to 26.5%
~ CaO+SrO+BaO is 7 to 21~ ¦
Within the broad group of alumino-borosilicate
compositions are ~hose exemplified by glass numbers 35, 36 and 37 ¦
in the above table. In this group of glasses ~SnO2+CaO is 0-9,
: ~ZrO2~La~03 is 2-4%, ZrO2~A1203 is 19-30 and ~CaO+SrO~BaO is 0-
18%.
The foregoing tables also show compositions tha~ are
free of added aluminum oxide, or very low amounts; i.e. on the
order of 2% or less. These compositions can be expressed by the
following listed ingredients in the indicated weight percent
based on oxides.
I ComponentsWeight Percent
¦ A123 0-2
B203 24 32
l Li20 5-9
j SiO2 16-40
Zr2 0-18
,1 -- 19 -- .
Il i
_~ lZl;~ 0
CaO 0~10
SrO 0-3
Na2 0-3
wherein:
~SnO2+CaO is 2-10%
~ZrO2+La~03 is 15-33%
~ZrO2+A1203 is 0-18
~CaO+SrO~BaO is 0-10%
Of these compositions some compositions exhibited no
cracks and may be expressed by the following listed components in
the indicated amounts in weight percent based on oxides.
Component Weiqht Percent
B203 24-30
Li2~ 5-9
5i2 28-40
Zr2 3-18
SnO2 0 2
La2~3 13 15
CaO 0-9
Na20 0-3
and wherein:
~SnO2+CaO is 2-9%
zro2+La23 is 17-33%
¦ ~CaO~SrO+BaO is 0-9%
25 ¦¦ To determine hardness of the glasses of the invention,
¦Ithe Knoop Hardness Numbers (KHN) were measured for the glasses
¦'set forth in Table 1 (abo~e). They ranged from 520-594.
IFommerically used lead glasses ranged from 250-300, in the s2me
¦~noop Hardness Numbers. RHN's are values of hardness expressed
30 ¦~s the load in kilograms divided by the projected area of a
l~iamond penetration in millimeters corrected for the resolution
- 20 -
1,
of the used microscope. E. G. Shand shows KHN's for soda-lime
glasses from 445-490, for alumino-silicate glasses ~550. (E. B.
¦Shand, "Glass Engineering Handbook", pg. 42, McGraw Hill, 1958).
I It therefore appears that the glasses of this invention
are exceptionally harder than lead containing decorating glasses
(5~0 vs. 250), they are somewhat harder than soda-lime glasses
(520 vs. 490) and similar to alumin-silicate glasses.
As previously mentioned, clear coatings may be prepared
from compositions of the present invention and then employed as
glazes or overcoats for other ware. To illustrate this
embodiment of the invention, lead and cadmium containing glasses I -
were overprinted with glass No~ 1 of Table 1 and cofired. When
tested for alkali resistance, the coated samples were
suprerior. They al~o showed high gloss and more intense color.
The following Table A lists the results obtained ~ith the three
most critical colors: red, orange and yellow - comparing coated
and uncoated samples. The samples did not have any cracks
eventhough glass No. 1 has a relatively high stress.
l Table A
Coated and Uncoated Lead and Cadmium Containinq Glass Samples
Red Oranqe - Yellow
Uncoated Coated Uncoated Coated Uncoated Coated
%Alkali koss 2.19 1.03 1.14 0.70 1.58 1.15
il Gloss Lost Retained LowHigh Low Medium
2sll Color Dull Intense GbodSlightly Gcod Good
!, Better
¦I Cracks Nb No No No No No
I i .
The compositions of the present invention can be used
l'to produce a wide range of pigment colors. The desirable colors
30~lare obtained by adding color pigments to a base glass (in single
l component) such as shown in Table 1 or to a mixture of two or
I ,
- 21 - I
-- ~21Z970
more glasse~ or to a mixture of glass plus filler. The range of
color pigments addition is from 0.5% to 15% by ~eight. The low
limit 0.5% of white titania oxide is used to achieve white
translucent color effects commonly used in so-called "etched
5 glassware". The upper limit of 15% is used in complex color 1-
requiring several pigments including opacifier agents. The most
useful range is from 4% to 12~ of pigments used for all basic and
relatively simple color tones like black, white, yellow, orange,
browns and tans.
Table 2 lists several important colors; yellow,
orange, brown and maroon with their characteristics. These
results illustrated the stress reductions achieved by additions
of the low expansion filler ~-eucryptite from 1700T to 320C. The
pigment chemistry is shown on line 2 of Table 20 From 1 to 15%
pigment is generally used. Line 3 lists the percentage of the
color pigment used. ~-eucryptite percentage is shown on line
4. The loss in weight in accelerated alkali test is listed on
line 6. Line 7 shows the induced stress as explained above.
Sample No. 6 had stress of 945 psi tension and it did not show
any cracks. The thin printed and fired layer had a stress of 160 i
psi tension. This approach to decreasing the induced stresses
has a disadvantage of less smoothness and gloss due to relatively
coarse (20-44 microns) ~ -eucryptite partlcles used for better
l results. Low expansion ~-eucryptite is described in pending U.SO
25~ patent application Serial No. 286,105 filed July 22, 1981 of
Perry Pirooz, the entire disclosure of which is relied on and
I incorporated herein by reference. From about 5 to 15% of low
¦ expansion fillers may be used to prepare colored enamel in
accordance with thi~ aspect of the invention.
- 22 -
!l ~
~2~Z970
l li
TABLE 2. COLORS
1 2 3 4 5 6 7
ColorMaroon Yellow BrGwn Buff Deep Orange
Tan
Pigment Fe203 CrNbTi FeZr FeZnTi FeZn CrWTi
S % Pigment 2 5 5 5 5 10
Filler 13 13 13 13 13 13 Beta- i
Eucryptitej
~ Loss Alk. 1.85 1.6g 1.76 l.ll 1.62 0.89
Flow 1O071 1.020 1.060 1-050 1.062 1.031
Stress 200C 315C 320C 8~0T 610T 945TPellet about
100 mils
Cracks No ~o No No ~o Mo
Base Glass
It was found that the present compositions such as
illustrated in Table l having high tension stresses and cracks
can be enhanced by incorporating low thermal expansion fillers
which effectiveiy reduce the apparent stress of this composite
mixture. Additions from 1% to 15% of e.g., ~-eucryptite were
effective reducers of high tensions. The amount of these fillers
depends on the original stress of the base glass used. For
example, glass No. 21 requires only 1% of ~-eucryptite to
eliminate visible cracks. Composition No. 16 needs maximum of
15~ of ~-eucryptite to pass the no crack criteria.
Although many glasses of Table 1 can be used as single
base glass components, they are some with high tension
I i stresses. This stress can be decreased to the good level by
addition of another glass from in Table l with compression stress
or very low tension stress. This second component glass is
¦ selected from listed glasses like No. 5, 13, 22 and 23. It was
~ found experimentaly that small amounts of 2% additions of the
above glasses will decrease the tension stress below the cracking
,,
l I ,
~` lZ~LZ970
limit. These glasses can be added up to 95~ to form useful
combinations. Consequently, range of selected glasses is from 1
to 99%. The proper selection is made by the specific
requirements of the flow numbers for the specific color
pigments. Some pigments decrease the flow substantially and
others have very little or no effect on flow number.
For example, the glasses No. 4 and No. 13 have good
flows as single components (1.200, 1.081, 1.020). On the other
hand, glass No. 23 is less flowing and requires addition of No. 1
glass.
To illustrate this aspect of the invention, curved 6
ounce orange juice tumblers (Bolero) were printed by Hot Melt
(hot wax) inks with "wheat" design, with several colors ranging
from yellow to orange, by a technique known as "blend". Two
basic colors are blended together at the middle of the screen to
achieve a variety of color shades. In Table 3, the six samples
used glass No. 13 and glass No. l with the ratio No. 13 to No. 1
from 1 to 3. Tumbler No. 6 had ratio l and tumbler No. 5 had
ratio 3 as seen below. Small amounts of low expansion fillers
were added to this mixture (e.g. 2~ ~-eucryptite ~ 1% Cer-Vit
¦ C-101). Table No. 3 lists the obtained results. The best
results are listed under tumblers No. 1 to 3. The glass in these
color mixtures was finely ground to less than 12 microns.
Tumblers No. 4 and 6 were printed by exactly the same mixture as
25 lltumblers No. 1-3, but with particles sizes less than 44 microns
¦l~-325 mesh). The alkali losses in percentages were calculated
~from total loss in weight by substracting the weight losses due
to the unprinted tumbler.
,, ,
Il - 24 - ~l
.,
i !
~ l
TABLE 3. TUMBLERS - WHEAT DESIGN
Tumbler 1 2 3 4 5 6
% Loss Alk. 0.5 1.0 0.8 1.32 1.383.11
% Loss Acids 2.932.57 1.645.74 7.454.38
Flow 1.060 1.0201.043 1.0401,020 1.051
Stress 250C315C 260C715C 825C815T
Ratio Glas~ 13 2 2.2 2 2.6 3
The stress numbers in Table 1 can be converted to the ',
standard coefficients of thermal expansion ~x 10-7 per degree
Centigrade (0-300C) by a experimen~ally determined conversion
factor 154 per unit of expansion. The listed s~ress numbers
divided by the factor of 154 yields units of thermal expansion
differences between the base glass (the tumbler glass) with a
coefficient (~) of 83 x 10-7 per C and the glasses of this
invention. The compression stresses indicate thermal expansions
lower than the tumbler glass and the tensions indicate thermal
expansions higher than the base glass. Consequently, when
tension is observed, the calculated units are added to the 83 x
10-7 per C. On the other hand, when compression stresses are
observed, the calculated units are subtracted fro~ the 83 x 10 7
per C.
For example, in sample No. 1, the observed stress is -
¦1700. The calculation is then carried out as follows:
¦¦ 1700 tension divided by 154 = 11.04 units
83 + 11.04 = 94.04 x 10-7 per C
This compares favorably to a measured value of 94.1 x
10-7 per 9C.
In another illustration, ~or sample No. 13, a
l compression stress of 1080 was measured.
1080C divided by 154 = 7.01
-- 2 5
! i
l~lZ~70
83 - 7.~1 = 75.99 compared to the measured value of
~76.1.
For sample No. S, the compression stress was mesured as
460.
¦ 460C divided 154 = 2.99
83 - 2.~9 = 80.01 compared to measured value of 80.00.
In making the glasses as shown in Table 1, various
ingredients were melted; generally, in quantities ranging from 10
to 50 pounds. Glass No. 1 was made in a quantity of 3,000 pounds
using the following batch compositions which are typical raw
materials which can be used for forming the glasses of the
invention.
The following composition is based on a 100 pounds of
batch material or approxima~ely 85 pounds of the resulting glass:
Batch Inqredients Amount~
Glass Sand 7.7
Alumina (A-10) 12.7
Anhydrous Boric Acid 23.6
Lithium Carbonate 12O0
¦ Lathanum Carbonate 2.5
Nepheline-Syenite 7.8
~! Cryolite 4.0
~,! Milled Zircon 6.1
25 ¦ High Calcite Limestone 23.6
!~ loo pounds
l~ The above-identified batch materials were melted at a
¦Itemperature of 2200~F for 2 hours. The melt was stirred eight
¦,times and thereafter cooled, The glass was then formed into
30 Ichips by using a water-cooled rolling mill in accordance with
conventional procedures. Because of the high volatilization
- 26 -
,
. I I
lZlZ~70
rate, it is desirable to minimize the loss of boric oxide. The
chips formed should be clear and transparent without any opaque
inclusions which may evidence the presence of undissolved
l alumina. Stirring is necessary in order to minimize separation
of the top layer which contains boric acid and silica and a
bottom l~yPr which contains alumina and zircon.
Two additional batch compositions are shown below to
illustrate the type of materials used for purposes of the
invention.
10 ¦ atch Raw MaterialsGrams
Ottawa 290 (sand) 27.8566
Anhydrous boric acid36.8717
Calcined Kyanite 59.6637
Milled Zircon 11.9792
Anhydrous borax 19.9661
Lithium carb~nate 39.3631
Stontium carbonate25.4686
Lanthanum oxide 11.9393
Total Batch 233.1082 gas. Total glass weight 200.000
20 grams. Fusion loss 33.1082 grams.
Batch Raw MaterialsGrams
Ottawa 290 (sand) 32.4947
Anhydrous boric acid51.0280
¦ Calcined Kyanite 52.5354
25 ¦ Milled Zircon 11.9665
I Anhydrous Borax 19.9441
¦ Lithium carbonate 39.3203
High Calcite Limestone 32.6886
~ Total batch 239.9777 grams. Total glass weight 200.000
30~lgrams. Fusion loss 39.777 grams.
~i
- 27 -
1.
z~9~ l
The fiber soEtening point range Eor these compositions
is 535C to 609C.
Further variations and modifications will become
l apparent to those skilled in the art from the foregoing and are
intended to be encompassed by the claims which Eollow.
il I
.
~' ,
Il 28 - I
., .
.: ,
