|Title of Invention
|There is disclosed a glass composition comprising 0.5 - 30 wt% bismuth oxide, 0.01 - 5 wt% zinc oxide, and 54-70 wt% silica, in combination with less than 5 wt% cobalt oxide, and less than 0.1 wt% of each of cesium, lanthanum, molybdenum, strontium, and tungsten oxide.
The present invention relates to a glass composition comprising bismuth oxide, zinc oxide
and silica in combination with other ingredients and application of the same.
Two well-known glass fiber manufacturing methods are known as the rotary method and the
flame blown method. Another well-known and widely used method is the Controlled Attenuation
Technology method, which is a modification of the rotary method. Manufacturing glass by these
methods requires heating glass compositions past their melting temperatures into a working
temperature range. Typical glass compositions used in making glass fibers have melting
temperatures of about 2700°F (about 1482°C) and working temperatures (temperature ranges
between glass viscosity 100 and 10000 poise) of about 2600°F (about 1427°C). Existing
compositions have relatively narrow working ranges, making the forming of glass fibers of desirable
diameters and lengths difficult because it is difficult to maintain the glass compositions in the
workable range. Additionally, the relatively high melting temperatures require large amounts of
energy to melt the compositions, which can be very costly.
In addition, typical glass compositions used for making glass fibers have liquidus
temperatures of about 1800°F (about 982°C). The liquidus temperature of typical compositions used
for making glass fibers limits the useful life of fiberization equipment due to the high temperatures at
which the equipment must operate. This is especially true when a spinner disc is employed in the
fiberization equipment. A glass composition having a relatively low liquidus temperature also is
useful for reducing or preventing crystallization of the glass during the fiberization process.
Glass fibers are used in a variety of applications. For example, glass fibers
are used in several manners in batteries. Glass fibers are typically used as a
separator that is preferably inserted between negative and positive plates of the
battery. In addition, glass fibers are used as a part of a modified material mixed with
a paste on the negative or positive plates of a battery. Further, glass fibers are used
as a pasting paper that is applied to the surface of the plates to reduce the liberation
of lead dust during manufacture.
Glass fibers tend to become brittle in humid environments, leach favorable
and unfavorable components, and are unstable in acidic and/or alkaline
environments. These characteristics of certain glass fibers can limit their usefulness
in applications such as battery separators or filters. Ion leaching, for example, is a
glass fiber surface phenomenon. The amount of ions lost from a glass fiber is
proportional to the exposed surface area. Surface area considerations are typically
greatest for glass fibers having diameters of less than about 5-7 urn. In some glass
fibers certain metal oxide impurities (e.g., platinum oxide, iron oxide) leach out of
the fibers and have a detrimental effect on the life of the battery.
Known glass compositions do not meet desired characteristics.
Disclosed are glass compositions and glass fibers formed from certain
embodiments of the disclosed glass compositions. Particular embodiments of the
disclosed compositions and fibers have broad working temperature ranges and
relatively low melting temperatures that can prolong the useful life of fiberization
equipment and decrease the costs associated with producing glass fibers. Moreover,
particular embodiments of the disclosed compositions and fibers have good acid
and/or alkaline resistance and include beneficial ions, such that when leaching does
occur, the leached ions have a positive effect in the particular application in which
the fibers are used, such as in a battery separator. Also disclosed are certain
applications for such glass fibers.
Certain embodiments of the glass compositions include, among other
components, bismuth oxide. Certain embodiments of the glass composition include
about 0.5-30% bismuth oxide of the composition by weight and silica oxide at about
54-70% of the composition by weight. Embodiments of the glass compositions may
also include other components. For example zinc oxide can make up about 0.01-5%
of the composition by weight.
Disclosed are glass compositions including, among other components,
bismuth and/or bismuth compounds. The disclosed glass compositions are the
compositions of the glass at the molten stage, which composition is the same as that
of resulting glass fibers formed from such glass compositions. The disclosed glass
compositions may vary from example "ingredient lists" for forming such glass
compositions as certain ingredients may change form once melted, becoming a part
of the glass composition. Example glass composition ingredient lists are set forth
below with the discussion of example methods for making particular embodiments
of the disclosed glass compositions.
Embodiments of the disclosed glass compositions may comprise one or more
of the following components within, e.g., ranges set forth in Table 1.
compositions, however, include a certain amount of bismuth, typically in the form of
an oxide, present in an amount of from about 0.5 wt % to about 30 wt % Bi203.
Good results have been obtained with a bismuth component present in the
composition at from about 1 wt % to about 15 wt % Bi2O3. It is possible that there
would be negligible amount of reduction of Bi2O3 into metallic form. However,
whatever form of bismuth is used for the glass composition, the raw bismuth
material will turn into bismuth oxide upon melting of the composition.
Alone, Bi2O3 will not form glass. Bismuth oxide may be used as part of a
binary glass composition. For example, bismuth oxide can be added to Si02 in a
concentration up to about 40 mol %. Bi203 forms glass with several other oxides as
well, for example K20. Bi2O3 acts in a glass composition in a manner similar to
B2O3, A1203, La203 or PbO, in that it decreases glass melting temperature, glass
viscosity, and allows fiberization of the glass at lower temperatures. Bismuth oxide
structural elements are incorporated into the glass matrix and act to strengthen the
resulting glass structure, e.g., glass fibers.
In addition, bismuth oxide acts to decrease the glass softening point and
melting temperatures (as discussed below and shown in Table 8). Addition of about
1% Bi2O3 decreases the softening point by about 2oF.. Addition of about 1% Bi2O3
decreases the melting temperature by about, 4° F.) The fiberization temperature, i.e.,
the temperature at which the glass composition viscosity is about 1000 poise is also
decreased in certain embodiments of the glass compositions. Particular glass
composition embodiments exhibit a fiberization temperature of about equal to or
lower thait 2000°F (about 1093°C) and certain embodiments exhibit a fiberization
temperature of about equal to or lower than from about 1800 to about 2050oF (from
about 982° C to about 1120° C). Glass composition embodiments having from about
2 to 10 wt% Bi2O3 decrease the fiberization temperatures of the glass compositions
by about 50°F to about 100°F (about 10°C to about 38°C)..
Glass compositions including the levels of Bi2O3 indicated also improve the
performance of glass fibers formed into hand sheets. Testing of such hand sheets
indicates that certain embodiments of the glass fibers disclosed will produce superior
battery separators or filter media. That is, such applications of the disclosed glass
fibers are relatively easy to manufacture and have the tensile, elongation, basis
weight, water wicking characteristics and other basic characteristics similar to or
better than what is presently available with commercial fibers (such as EF M-glass
illustrated in Tables 6 and 7 or JM 253 glass (available from, e.g., Johns Manville
Corporation and illustrated in Table 6)). Accordingly, certain embodiments of the
disclosed glass compositions do not compromise major media physical
characteristics needed of glass fibers formed thereof but instead additionally provide
enhanced performance due to particular enhanced or new glass properties, e.g., Bi
ion leaching that decreases off gassing in battery applications.
Further, particular embodiments of the disclosed bismuth-containing glass
compositions have increased devitrification resistance so that they do not become
crystalline during the fiberization process. Glass compositions having Bi2O3 in the
disclosed ranges showed higher resistance to devitrification (see Table 7). Modified
borosilicate glass, i.e., labeled as M-glass in the Table 7 is a man-made vitreous
fiber as published by the Nomenclature Committee of TIMA Inc. 91,93,
incorporated herein by reference. This glass composition was used as a reference to
determine effects of additions of Bi2O3 and ZnO to a glass composition. The M-
glass batch (mixture of all raw materials) was formed and then divided into three
parts. A first glass composition labeled "M glass" as shown in Table 7 was formed.
A second glass composition was formed by adding further components including
about 2 wt% ZnO and about 2 wt% Bi2O3 and a third glass composition was formed
by adding abou£.10 wt% Bi203, thereby forming two particular embodiments of the
disclosed glass compositions.
Bismuth ions in glass fibers formed from the disclosed glass compositions
will also act to improve battery performance and increase battery life (as discussed
below). The amount of bismuth desirable in the glass compositions is calculated so
that leaching does not compromise the structural integrity of the resulting glass
fibers over time. In particular applications it is desirable to have some bismuth ions
(or other ions as discussed) leach into solution but the leaching should not lead to
full fiber dissolution during, for example, battery operation. Glass fibers formed
from glass compositions having from about .0.5 to about 30% bismuth oxide provide
sufficient bismuth ion leaching such that the leaching does not compromise the
structural integrity of the resulting glass fibers over time but sufficient ions are
leached to limit or prevent hydrogen gassing in batteries. Glass fibers formed from
alternative embodiments of the glass compositions including from about 1 to about
15% bismuth oxide also provide sufficient bismuth ion leaching such that the
leaching does not compromise the structural integrity of the resulting glass fibers
over time but sufficient ions are leached to limit or prevent hydrogen gassing. This is
especially true in valve regulated (sealed) lead acid batteries. Hydrogen gassing
causes water loss, which shortens battery life and reduces performance.
The addition of Bi2O3 as indicated as well as from about 1 to about 4 wt%
ZnO also minimizes hydrogen gassing of VRLA batteries under float duty. Float
duty is the low-rate charge used to maintain a battery in a fully charged condition in
a standby application, as is known to those persons skilled in the art. ZnO in the
glass compositions and resulting glass fibers formed therefrom also significantly
improves water and acid durability of the glass fibers, significant for various glass
fiber applications such as battery and filter uses.
Some embodiments of the glass compositions and glass fibers may include
NiO or other suitable Ni ion sources. For battery applications, Ni ions increase the
charge acceptance of a negative plate of lead acid batteries. On the other hand Ni
may increase gassing. This negative effect may be suppressed by addition of Bi, Zn
and Ag ions to the glass compositions.
Typically silica is the main glass component. Silica forms a stable, durable
glass lattice and provides particular structural properties to the glass composition. In
particular embodiments of the disclosed glass compositions SiO2 is present at a
weight % of from about 54% to about 70%. In other embodiments of the disclosed
glass compositions SiO2 is present at a weight % of from about 56% to about 69%
and yet in other embodiments of the disclosed glass compositions SiO2 is present at
a weight % of from about 62% to about 70%.
None of the other glass formers (P2O5, B2O3) can provide with sufficiently
durable (and cheap) glass. That is, theoretically these oxides can substitute silica,
but they are expensive and glass compositions formed thereof will likely be less
durable - not sufficiently withstanding humid or acidic environments.
Alumina in a glass composition affects the glass water and acid durability.
Thus, alumina may improve an embodiment of the disclosed glass fiber's
performance in a humid atmosphere when used, for example, in filter applications.
On the other hand, a relatively high alumina content can significantly decrease the
Kdis (biological dissolution coefficient) of the glass fiber; making the glass less bio-
degradable. A useful alumina concentration may be from about 2% to about 4%.
Calcium oxide (CaO) and magnesium oxide (MgO) may be present in
particular glass composition embodiments to further stabilize the glass network and
provide the glass with particular advantageous structural properties. CaO acts to
decrease the viscosity of the glass composition and MgO acts to further slow the
crystallization rate. CaO and MgO increase glass fiber biological solubility.
Particular embodiments of the disclosed glass compositions include these oxides in
the advantageous ratio, CaO to MgO, of about 3:2 (i.e., a molar ratio of about 1:1).
Other particular embodiments include the oxides in the following amounts: CaO at
from about 3 wt % to about 6 wt % and MgO at from about 2 wt % to about 4 wt %.
Certain embodiments of the glass compositions include sodium oxide (Na2O)
and/or potassium oxide (K2O). These particular oxides may be present to aid in the
decrease glass melting temperature, glass viscosity, and, respectively, to allow
fiberization of the glass at lower temperatures. Addition of Na2O and K2O to some
extent may aid in increases the glass durability in acids. On the other hand, both
oxides may act to increase glass water and biological solubility. Embodiments of
the glass compositions including both oxides may provide further advantages due to '
the polyalkali effect (synergistic effect). Addition of K2O may also aid in the
decrease of a glass composition's propensity to the crystallization.
Certain embodiments of the glass compositions include boron oxide (B2O3)
to aid in the lowering of glass melting temperature, aid in the reduction of glass
viscosity, and to enhance resulting glass fiber elasticity. In addition, boron oxide
may be included in the glass composition to significantly increase glass fiber
biosolubility without deterioration of glass durability in water and in acid. Particular
embodiments of the glass compositions include from about 4 wt % to about 7 wt %
boron oxide. Certain embodiments of the glass compositions include barium oxide
(BaO) to aid in the moisture resistance of resulting glass fibers and may have a
positive affect on biological degradability of the resulting glass fibers.
Certain embodiments of the glass compositions include fluorine (F2) and
lithium oxide (Li2O) in relatively small amounts (for example, less that about 1 wt
%) to aid in the decrease of the glass melting temperature, to improve melt fining,
and to aid in the lowering of the glass viscosity. Typically Li2O is present only as an
impurity. Certain embodiments of the glass compositions include iron oxide in trace
quantities since it is also normally introduced as an impurity in the SiO2, A1203,
CaO, and/or MgO batch materials. A typical content of iron in a glass composition
is from about 0.05 wt % to about 0.1 wt %. Other typical impurities include SrO,
and/or MnO. Glass composition embodiments may include such oxides in amounts
less than abput 0.1 wt %. In general, the disclosed glass compositions include less
than abput 0.05 wt%(Ti02-(from the total amount of glass) and CoO less than
0.01wt%. Both CoO and TriO2 have negative influence on battery operations. If
glass fibers (or a glass composition) have a blue tint, it is typically due to Co
leaching from the rotary disc and in such cases the resulting glass fibers /products
are typically rejected. In general, the disclosed glass compositions include less than
about 0.05% ZrO2. Although glass compositions may include as much as 0.3-0.4
wt%. ZrO2, that particular component does not appear to have a negative impact on
battery operations, but it does drastically change glass properties and thus most of
the disclosed glass compositions include less than about 0.1 wt% ZrO2.
One or more of the above-listed glass composition ingredients may have
suitable substitutions as known to those of ordinary skill in the art. Alternative
compounds and oxides may include for example, rubidium oxide as a substitute for
K2O. Another example may be the partial substitution of CaO with SrO or partial
substitution of AI2O3 with La2O3.
The glass compositions as disclosed herein may be made by methods known
to those persons of ordinary skill in the art. For example, an embodiment of the
glass compositions disclosed herein may be prepared using chemical reagent-grade
materials such as those listed in the tables above. The ingredients to form the
desired glass compositions may be, e.g., added to a clay crucible and melted at about
1350°C or lower depending upon the exact glass composition being formed, with
about a one hour dwell time at maximal temperatures. The melted glass
composition may then be poured into steel molds in the shape of disks. Glass discs
may then be annealed at about 600°C and then cooled to room temperature.
As discussed above, embodiments of the glass compositions disclosed have
surprisingly relatively low softening points. Particular embodiments of the glass
compositions have softening points of from about 1230oF to about 122565°F (from
about 665.6°C to about 680°C). The softening point is the temperature at which the
viscosity of a glass composition is 10 in power 7.6 poises (rj =log 7.6). Particular
embodiments of the glass compositions have glass softening points as shown in
Table 7. As shown, an embodiment of the disclosed glass compositions having
about 10 wt% Bi2Oj decreases the softening point of the glass to about 1267° F (see,
e.g., Table 7, Composition 7). Softening points of the disclosed glass compositions
are lower than the commercially available glass compositions as illustrated in Table
7 wherein examples of existing glass compositions labeled "M-glass" and "JM 253"
have typical conventional glass composition softening points, with M-glass having a
softening point at abou(1300°FN(704oC) and JM 253 at abou(i2350F (668°C).
Because particular embodiments of the presently disclosed glass
compositions have lower softening points, the disclosed glass compositions melt
faster and require less energy to be melted and fiberized. Lower melting and
fiberization temperatures promise savings in equipment due to lower wear of parts
contacting melted glass and lower energy costs. Glass softening points were
determined by the Littleton method (per ASTM C-388, incorporated herein by
Glass powder having a particle size in the range of from about 297 to about
590 µm (i.e., a particle fraction between mesh screen 30 and 50) was utilized to test
certain of the glass compositions' properties. Because the process of making and
testing glass microfibers is a long and expensive, before glass is fiberized. For
screenings, the powder technique was used. Small amounts (e.g., about 1 pound) of
particular glass compositions were melted and then cooled and crushed into a
powder. Thus, there was a significant increase in the glass surface area. The testing
included glass composition powders having particle sizes within a predetermined
range. This method allows prediction of the fiber durability in different
environments and solutions, namely acidic, neutral water, basic and in simulated
lung fluid, eliminating time consuming and costly experimental glass fiberization
Certain embodiments of the glass compositions disclosed herein provide for
lower fiberization temperatures. In general, the fiberization temperatures of the
disclosed glass compositions are from about 1800oF about 2050°F about 982°C
to about 1120°C) or about/l00oF (37.8°C) lower than commercially available glass
Certain embodiments of the glass compositions disclosed herein provide
relatively very low crystallization rates, an important technological property for
glass fiberization. The crystallization rate is the speed of glass devitrification at
specific temperatures or temperature ranges. Crystallization rates of particular
embodiments of the glass compositions disclosed were evaluated by holding glass
powder in a furnace at the following temperatures (in °C) for about two hour dwell
periods: 1000, 950, 900, 875, 850, 825, 800, and 700. Results are shown in Table 7.
As shown in Table 6, particular embodiments of the disclosed glass
compositions have surprisingly superior water durability as compared with
commercially available glass compositions. For example, see Table 6 wherein
representative commercially available glass compositions "M-glass" and "JM 253"
glass have much lower durability in water as compared to disclosed compositions
nos. 2-5. In addition, disclosed glass composition no. 2 has surprisingly superior
tensile strength for 0.8 µm and 1.4 fan fibers, respectively, 4.3 and 3.3 pounds/inch
when formed in hand sheets.
Also disclosed herein are glass fibers formed of the disclosed glass
compositions. The glass compositions disclosed may be formed into, e.g., glass
fibers using conventional methods and equipment For example, the glass
compositions may be fiberized by rotary, Controlled Attenuation Technology, and/or flame blown processes.
Glass fibers as disclosed herein may be formed from any of the multitude of
-embodiments of the disclosed glass compositions. Embodiments of the disclosed
glass fibers have many potential applications. They may be used, for example, in
_ various-manners and locations"in:batteries; to form filters designed for air and/or
liquid filtration, and as insulation material, (e.g., electrical and/or thermal
insulation). The desired glass fiber composition and size is determined based on the
intended use for the glass fibers, as would be known to a person of ordinary skill in
the art For example, to obtain glass fibers useful in both filter and battery
applications disclosed glass composition: 2 (see Table 3) may be formed into about
0.8/zm and. 1.4 /an glass fibers
Embodiments of the disclosed glass fibers typically exhibit a variety of
advantageous properties. Such disclosed glass-fibers have superior water and acid
durability as indicated in Table 6 and superior tensile strength (hand sheets formed
of such fibers showed tensile strength of about 4.3 and 3.3 pounds/inch,
respectively) Such.characteristies make these disclosed glass fibers suitable both
for battery separators and filtration media.. Certain embodiments also have relatively
low biopersistance,meaning that inhaled fibers will dissolve and be eliminated more
readily nx the longs. The biopersistance factor, as known-to those skilled in the art,
is measured by the Kdis of the glass fibers in simulated lung fluid. Certain
embodiments of the glass fibers achieve a Kdis of less than about 150 ng/cm2h and
other embodiments may exhibit Kdis values in the range of from about 50 to about
Glass biosolubility has been tested on glass particles of size 75-106 µm made
from disclosed glass composition embodiments 6 and 7 in Table 3. The particles
passed through sieve 140 and remained on the sieve 200 were stored in vials with
simulated lung fluid (SLF) for about 96 hours at about 37°C in a shaker. The
dissolution rate was again determined based on the leachate analysis performed with
an ICP. Leaching rates were compared based on the levels of the leached ions in
solution. Results are shown in Table 9. An embodiment of the glass composition
having 10 wt% Bi2O3 doubled the glass biodissolution rate in simulated lung fluid.
This indicates that a glass composition having Bi2O3 provides an increase in
biosolubility without compromising other desirable properties of the glass
Further, certain embodiments of the disclosed glass fibers including the
levels of Bi2O3 indicated may also improve the performance of glass fibers formed
therefrom because longer fibers can be produced. Certain embodiments of the glass
fibers also show a significantly increased density as compared to equivalent glass
fibers currently available. Accordingly, certain glass fiber products, such as glass
fibers used in battery separators provide higher porosity rates in the separator
because for the separator to have the same weight of glass fibers, less glass fibers are
needed. The same would hold true for other glass fiber products such as filtration
and insulation products where the weight of the fibers versus the amount of fibers
needed is of concern. For example, certain embodiments of the disclosed glass
fibers have density values from about 2.5 to about 2.8 g/cm3 as shown in Table 7.
Glass fiber embodiments having such density values means that hand sheets
made from the same size glass fibers formed from the disclosed glass compositions
having varying bismuth oxide concentrations will exhibit different specific surface
areas and different air resistant values. For example, density values of from about
2.50 to about 2.85 are obtainable with certain embodiments of the presently
disclosed glass fibers when bismuth oxide concentrations of the glass fibers are from
about 1 to about 15 wt%. Density values were obtained by use of a Micromeritics
AccuPyc 1330 picnometer according to the method set forth in the Micromeritics
Embodiments of the glass fibers disclosed herein have specific surface areas
(SSAs). Relatively low SSAs of certain glass fiber embodiments are important for
glass fiber durability considerations. The larger SSA fibers' value, the smaller the
fiber diameter. Different applications require glass fibers of different diameters and
respectively different SSA values. SSA and fiber diameter values are inversely
dependent. The larger the SSA the smaller the diameter of the fiber and the stronger
the fibers when subjected to ambient atmosphere attack (e.g., humidity, acid, etc.).
SSA values are especially important for glass fiber products having glass fibers of
relatively large specific surface areas as larger surface areas can detrimentally affect
the product. For example, ion leaching is a glass fiber surface phenomenon. The
amount of ions lost from a glass fiber is proportional to the exposed surface area.
Surface area considerations are typically greatest for glass fibers having diameters of
less than about 5-7 µm but the SSA values of larger or smaller diameter glass fibers
is also of importance. Certain embodiments of the disclosed glass fibers have SSA
values of from about 1.1 to about 1.2 g/m3 for abouil.4 µrn diameter fibers and 1.95
to about 2.0 g/m3 for about 0.8 µrn diameter fibers.
SSA values of certain embodiments of the disclosed glass fibers were
determined as set forth in EFCTM 157: Specific Surface Area Analysis using Argon,
which is incorporated herein by reference. The apparatus used was a Micromeritics
2375 BET SSA analyzer.
As mentioned above, leaching of ions from glass fibers in various glass fiber
products can be advantageous or detrimental to the product. For example, with glass
fiber filter products leaching would be detrimental for a variety of reasons, such as
disintegration of the fibers. Leaching of the glass fibers has a direct affect on the
durability of the fibers. In addition to the affect of leaching on the durability
requirements of glass fibers, other considerations depend on the applications for
which glass fibers are used. For example, glass fibers used in battery separators
preferably have low levels of leaching of certain metal oxide impurities (e.g.,
platinum oxide, iron oxide) that can have a detrimental effect on the life of the
battery. On the other hand, certain ions (e.g., Bi, Ag, Ni, Cd, Ge, Sn, Zn) have
positive effects on battery performance (as discussed above), so leaching of these
ions may be beneficial. As discussed, these ions can reduce gassing, water loss and
improve charge acceptance by a battery's negative plate.
The durability of glass fibers is typically determined by the leaching rate of
the glass fibers in acid, neutral and alkaline conditions. Particular embodiments of
the disclosed glass compositions in powder form were tested for leach rates in acidic
environments. Leaching rates in acid were determined by analyzing leachates
obtained by boiling 2.5 grams of glass fibers in 100 gmsH2SO4 having a specific
gravity of 1.26 g/cm3 for three hours. DI water (up to 250 ml) was added to the
leachate. (See 8.2 ASTM 165, which is incorporated herein by reference.) Samples
of the resulting solution were subjected to inductively coupled plasma atomic
emission spectrometry (ICP-AES) model Perkin Elmer Optima 4300 DV to
determine the amount of each element present in the leachate. Final leach rate
results are shown in Tables 6, 8, and 10. The leach rates shown are averages of
three sample tests per composition tested.
The acid leaching test showed that the glass composition embodiments tested
have leaching rate within the range of current commercial glass fibers "408" made
from "M-glass" glass (available from Evanite Fiber Corporation of Corvallis,
Oregon) and glass fibers "206" made from "253" glass (available from Johns
Manville Company of Denver, Colorado). Leach rates of the embodiments of the
disclosed glass compositions tested are closer to the Johns Manville glass fibers
made out of "253 glass." All of the tested glass composition embodiments have
approximately the same acid resistance with a slightly higher value shown for
composition numbers 2,4 and 5 - the glass composition embodiments with ZnO and
the glass compositions with the highest Bi2O3 concentration.
Particular embodiments of the disclosed glass compositions in powder form
were tested for leach rates in water or neutral environments to determine the glass
fibers' moisture and water resistance values (See 8.2.TM. 166 incorporated herein
by reference). Leaching rates in DI water were determined by analyzing leachates
obtained by boiling 2.5 gms of glass fibers in 250 gms of DI water for 3 hours.
Samples of the resulting solution were subjected to inductively coupled plasma
atomic emission spectrometry (ICP-AES) model Perkin Elmer Optima 4300 DV to
determine the amount of each element present in the leachate. Final results as
shown in Tables 8 and 9 are averages of three sample tests per composition tested.
The tested glass composition embodiments illustrate that the resulting glass fibers
have water durability performance values that are compatible with the commercially
available fibers (i.e., in the range of 100 to 160 with weight losses below about 5 wt
%). Water durability performance is better for glass compositions having higher
ZnO and Bi2O3 content. Particular embodiments of the disclosed glass
compositions in powder form were tested for leach rates in alkaline environments.
Leaching rates in a base were determined by analyzing leachates obtained by
holding about 2.5 grams of glass fibers in 100 ml of 30% KOH at 125°F (about 50°C) for 3 hours
DI water (up to 250 ml) was added to the leachate. Resistance of fiber to acid and
water were tested per EFCTM 120: Extractable Metallic Impurities of Recombinant
Battery Separator Mat (RBSM) and Glass Fibers. Alkalinity is tested per EFCTM
119, incorporated herein by reference. Such conditions compare are equivalent to 5
years in a battery. Leachates were tested per EFCTM 120.
Samples of the resulting solution were subjected to inductively coupled
plasma.atomic emission spectrometry (ICP-AES)-model Perkin Elmer Optima 4300
DV to determine the amountof each element present ia the leachate Final results
shown in Tables 8 and 9 are averages of three sample test per cornposition tested.
Additionalleachate tests resultsfor specific embodiments are shown in Table 10.Increased
separator becanse dlaring initial wrapping;of the plates; the plates could be at a pH >
7. In addition, prior to formation of the battery, the density, or specific gravity of
the acid electrolyte can-approach that of water and result in alkaline conditions at
plate. In Table 10, Sample IDs designating compositions 1-5 are those compositions
"shown in Table 3. -The sample ID indicator "08"indicatesa glass fiber diameter of
0.8 µm, and "12" indicates a glass fiber diameter of 1.4 urn. The element
concentrations.are in ppm.
A glass composition having about 10 wt% of Bi2O3 (composition 7, Table 7)
has a decreased glass chemical durability (10-20%) in acid (1.26 g/cm? H2S04),
improved glass durabilrty in water, and signifieantly increased alkali resistance.
Surprisingly, the glass leaching rate of composition 7 in 0.5 NaOH + 0.5 Na2CO3
dropped almost three times (see Table 9). However the same phenomenon was not
shown in concentrated KOH (30%) for glass fibers madeout of compositions 1-5'.
The 30% KOH solution appeared equally destructive for all compositions tested.
Addition of 2% of Bi203 and 2% ZnO (composition 6, Table 10) did not
significantly change the glass properties. However, such a composition would be
very efficient for battery separators due to fact that it contains both ZnO and Bi2O3.
arranged to establish alternating positive and negative electrodes. A battery
separator may be disposed between each pair of electrodes. The separators may be
formed of insulating material and are used, in part, to prevent metallic deposits in
the battery from forming short circuits between the electrode plates. The separator
is porous, however, to the battery electrolyte so that current can pass from one plate
to another. Particular examples of battery separators and methods of making and
using them are disclosed in U.S. Patent Nos. 5,180,647; 5,091,275; 4,237,083;
4,113,927; 3,989,579; 3,845,737; and 3,450,571, which are all incorporated by
In examples of battery separators comprising the disclosed glass
compositions, glass fibers made from the disclosed glass compositions are used to
form the battery separator. The glass fibers may be used to form what is commonly
known as an absorptive glass mat separator, which typically is comprised of glass
fibers of varying length and diameter. In other cases the battery separator comprises
a mat formed of the disclosed glass fibers that is impregnated with a binder that is an
aqueous mixture of colloidal silica particles and a sulfate salt as described in U.S.
Patent No. 5,091,275 (the '275 patent). As explained in the '275 patent, the
separator can be made by forming the glass mat on a conventional paper making
machine (such as a Fourdrinier machine) and then exposing the mat to the binder in
an impregnating bath of an aqueous mixture of the binder, followed by drying of the
mat and compression to the desired separator thickness.
Whereas the disclosed glass compositions, glass fibers and applications for
the same have been described with reference to multiple embodiments and
examples, it will be understood that the invention is not limited to those
embodiments and examples. On the contrary, the invention is intended to
encompass all modifications, alternatives, and equivalents as may be included within
the spirit and scope of the invention as defined by the appended claims and as
disclosed in the specification.
1. A glass composition comprising 0.5 - 30 wt% bismuth oxide, 0.01 - 5 wt% zinc
oxide, and 54-70 wt% silica, in combination with less than 5 wt% cobalt oxide, and less than 0.1
wt% of each of cesium, lanthanum, molybdenum, strontium, and tungsten oxide.
2. The composition as claimed in claim 1, which contains 1-2 wt% bismuth oxide.
3. The composition as claimed in claim 1, which contains 9-15 wt% bismuth oxide.
4. The composition as claimed in claim 1, which optionally contains less than 0.1 wt%
CoO, ZrO2 or TiO2.
5. The composition as claimed in claim 1, wherein the fraction (wt%) of bismuth oxide
and zinc oxide in relation to silica is 0.059 to 0.29.
6. The composition as claimed in claim 1, which has a softening point of less than
There is disclosed a glass composition comprising 0.5 - 30 wt% bismuth oxide, 0.01 - 5 wt%
zinc oxide, and 54-70 wt% silica, in combination with less than 5 wt% cobalt oxide, and less than 0.1
wt% of each of cesium, lanthanum, molybdenum, strontium, and tungsten oxide.
|Indian Patent Application Number
|PG Journal Number
|Date of Filing
|Name of Patentee
|EVANITE FIBER CORPORATION
|1115 S.E. CRYSTAL LAKE DRIVE, P.O. BOX E, CORVALLIS, OR
|PCT International Classification Number
|PCT International Application Number
|PCT International Filing date