Title of Invention

A GLASS REINFORCEMENT STRAND

Abstract Glass reinforcement strand, the composition of which comprises the following constituents, within the limits defined below, expressed as percentages by weight: SiO2 5O to 60%, preferably SiO2 ≥ 52% and/or SiO2 ≤ 57% Al2O3 10 to 19%, preferably A12O3 ≥ 13% and/or Al2O3 ≤ 17%; B2O3 16 to 25%; ZrO2 0.5 to 1.5%; Na2O ≤ 1.5%, preferably Na2O ≤ 0.8%; K2O ≤ 1.5%, preferably K2O ≤ 0.8%; R2O ≤ 2%, preferably R2O ≤ 1%? CaO ≤ 10%; MgO ≤ 10%; F 0 to 2%; TiO2 0 to 3%; RO 4 to 15%, preferably RO ≥ 6% and/or RO ≤ 10%; and Various ≤ 3%, where R2O - Na2O + K2O + Li2O, and RO = CaO + MgO. The dielectric properties of such glass compositions are particularly advantageous in the MHz and GHz ranges.
Full Text - 1 -
GLASS STRANDS CAPABLE OF REINFORCING ORGANIC AND/OR
INORGANIC MATERIALS, PROCESS FOR MANUFACTURING
SAID STRANDS AND COMPOSITION USED
The present invention relates to glass strands (or
"fibers") , that can be used for reinforcing organic
and/or inorganic materials and can be used as textile
strands, these strands being able to be obtained by the
process which consists in mechanically drawing streams
of molten glass flowing out from orifices located at
the base of a bushing generally heated by resistance
heating.
The present invention is aimed more particularly at
glass strands of low dielectric constant having a
particularly advantageous novel composition for forming
fine strands.
This is because there is a growing demand for glass
strands whose permittivity and dielectric losses are
low, these being mainly used to form lightweight
fabrics, which are used in order to reinforce
printed-circuit substrates. The latter consist mainly
of a reinforcement, especially glass strands, and a
resin, on which substrates various electrical and/or
electronic components are placed.
With, on the one hand, the increase in the speed of
processing of electrical and/or electronic signals,
which involve signals of ever higher frequency, and, on
the other hand, the miniaturization of the components
which allows their density on a substrate to be
increased, the dielectric properties of this substrate
become crucial. If these properties do not have the
expected performance, there may be a risk of
overheating and/or of signal distortion. Moreover, to
help in miniaturization, strands of ever smaller

- 2 -
diameter are sought in order to reduce the thickness of
the components and to improve their planarity.
The polymers conventionally used for printed-circuit
boards consist essentially of epoxy resin. Polymers
having superior dielectric properties are known at the
present time, especially polyimide resins, cyanate
ethers, polyesters or even PTFE, the dielectric
properties of which are satisfactory.
Any improvement in the dielectric properties of a
printed-circuit board must therefore essentially rely
on improving the properties of the reinforcement,
represented here by the glass strands according to the
present invention, which occupy in general about 60% of
the volume.
A glass subjected to an AC current converts some of the
latter into electrical energy dissipated in the
material. This electrical energy is known as dielectric
loss. The dielectric losses are proportional to the
permittivity and to the loss tangent (tan) which
depend on the composition of the glass for a given
frequency. The dielectric losses are expressed {see for
example J. C. Dubois in "Techniques de 1'Ingenieur
[Engineering Techniques"] , heading: "Electronique
[Electronics]", Chapter E 1850: "Proprietes
dielectriques des polymeres [Dielectric properties of
polymers]") by the formula:
W = kfv2tan
where: W is the electrical energy dissipated in
the glass or the dielectric loss;
k is a constant;
f is the frequency;
v is the potential gradient;
 is the permittivity; and
tan is the dielectric loss tangent or
dielectric dissipation factor.

- 3 -
It is usual to denote etan5 as z" , if tan8 ≤ 0.1.
It is clearly apparent from this formula that the more
the frequency increases, or the more  and/or tan
increase, the greater the dielectric losses become.
In the rest of the text, the term "dielectric
properties" refers to the pair (, ") . To minimize the
distortion of a signal, it is desired that both e and "
be as low as possible.
It is therefore important to obtain glass compositions
that can be fiberized, especially under the conditions
of the process already mentioned, in order to form
continuous reinforcing strands, having dielectric
properties and a diameter that are compatible with the
requirements of the latest printed circuits.
More specifically, a tendency to increase the operating
frequencies of components, with frequency ranges of the
order of GHz (gigahertz), especially 0.9 and 1.8 GHz in
the case of telephony, should be noted.
It is therefore very important to study the behavior of
glass strands in this frequency range and to optimize
their composition so as to limit the dielectric losses,
especially for this field of application.
It should be noted that the vast majority of prior
studies published in this field relate to dielectric
properties of glasses in a frequency range of the order
of MHz (megahertz).
The objective of the present invention is to provide
novel glass compositions for forming reinforcement
strands having dielectric properties of the same order
of magnitude as those of the known glasses within the
MHz range, which glass compositions have at the same
time improved dielectric properties in the GHz range

- 4 -
for a smaller strand diameter, while still having
satisfactory fiberizing properties in order to obtain
reinforcement strands economically.
Furthermore, it is desirable that the glass strands in
question can be fiberized under conditions giving rise
to the lowest possible amount of breakage.
In the rest of the description, the following are
defined:
A the dielectric properties there being for the
"MHz range", a frequency range in which the
characterization of the dielectric properties of the
glasses is carried out, especially at 1 MHz and for the
"GHz range", a frequency range in which the
characterization of the dielectric properties of the
glasses is carried out, especially at 9.5 GHz;
A the fiberizing properties, which are especially
determined by:
the temperature corresponding to a viscosity of
103 poise (decipascal.second or dPa.s), denoted by
"T (log = 3)", which gives precious information about the
temperature around which the fiberizing is generally
carried out, especially from platinum bushings;
the "liquidus temperature", denoted "Tliq", which
corresponds to the temperature at which the growth rate
of the most refractory crystal is zero. The liquidus
temperature gives the upper limit of the temperature
range in which the glass may have a tendency to
devitrify.
It is considered possible to fiberize the glass
economically if T(log = 3) is less than or equal to
1350°C and if Tliq is more than 100°C, preferably more
than 300°C, below T(log = 3). The greater this
difference between T(log = 3} and Tliq, the more likely
the fiberizing will be carried out without any
incident, and the more the risks of breakage during
fiberizing are minimized.

- 5 -
The glass reinforcement strands most commonly used are
thus strands formed from glasses which derive from the
1170°C eutectic of the SiO2-Al2O3-CaO ternary diagram,
particularly the strands referred to as E-glass
strands, the archetype of which is described in Patents
US-A-2 334 981 and US-A-2 571 074. E-glass strands have
a composition essentially based on silica, alumina,
lime and boric anhydride. The boric anhydride, present
in amounts ranging in practice from 5 to 13% by weight
in "E-glass"-type glass compositions, replaces some of
the silica. E-glass strands are furthermore
characterized by a limited content of alkali metal
oxides (essentially Na2O and/or K2O) . Although their
fiberizability is good (T(log=3) of around 1200°C and
Tliq of around 1080ºC), their dielectric properties,
however, prove to be insufficient as regards the new
requirements for printed-circuit substrates.
Another family of glass strands is known and obtained
from compositions very rich in silica and boron. The
glasses of this family, known by the name "D-glasses"
comprise about 75% of SiO2, 20% of B2O3 and 3% of alkali
metals. Although these glasses are attractive for their
dielectric properties, also they are very difficult to
fiberize (T(log = 3) ≥ 14 00°C) particularly when the
strands to be obtained are fine (filament diameter ≤
lOm) . The yield of this type of strand is low (high
degree of breakage) and therefore their production is
particularly expensive.
Novel families of compositions have recently been
proposed which make it possible to obtain useful
dielectric properties and achieve relatively economic
fiberizing conditions. These compositions are described
for example in applications WO-A-96-A-/39363 and
WO 99/52833.

- 6 -
These compositions, although having acceptable
dielectric losses in the MHz and GHz ranges, are
unsatisfactory for forming fine strands since the
degree of breakage during fiberizing remains high.
Another family of compositions already proposed
recently is disclosed in FR-A-2 825 084. These
compositions are capable of giving reinforcement
strands that can be satisfactorily fiberized
economically and make it possible to achieve good
dielectric properties in the GHz range. It seems that
the high performance level is due to the presence of
P2O5 in the compositions.
Although the addition of P2O5 proves to be beneficial
for the dielectric properties, it also increases the
risk of demixing and consequently the formation of a
hetereogeneous glass which breaks more easily during
fiberizing.
It has now been found that the addition of zirconium
oxide (ZrO2) into a composition based on the
SiO2-Al2O3-B2O3 combination makes it possible to obtain
strands with a small diameter, especially less than or
equal to 10 n, preferably less than or equal to 7 n
or even around 5 n under good fiberizing conditions
with a reduced breakage rate, while still maintaining
acceptable dielectric properties in the MHz and GHz
ranges.
Thus the glass strands according to the invention are
obtained from a composition essentially comprising the
following constituents, within the limits defined
below, expressed as percentages by weight:

SiO2 50 to 60%;
A12O3 10 to 19%;
B2O3 16 to 25%;
ZrO2 0.5 to 1.5%;
Na2O less than or equal to 1.5%;

- 7 -

K20 less than or equal to 1.5%;
R20 (Na2O+K2O+Li2O) less than or equal to 2%;
CaO less than or equal to 10%;
MgO less than or equal to 10%;
RO (CaO + MgO) 4 to 15%;
F 0 to 2%;
TiO2 0 to 3 %; and
Various less than or equal to 3%.
The compositions according to the invention make it
possible to obtain satisfactory and advantageous
fiberizing properties, allowing economic fiberizing to
be carried out, especially because T(log=3) ≤ 1350°C.
The compositions according to the invention have an
acceptable liquidus temperature, especially less than
or equal to 1150°C, without major risk of
devitrification during fiberizing in the cold regions
of the fiberizing crucible and in the feeders
conducting the glass from the furnace to the fiberizing
crucibles.
Silica is one of the oxides which forms the network of
the glass compositions according to the invention and
plays an essential role in stabilizing them.
The silica (SiO2) content of the selected compositions
is between 50 and 60%, especially greater than 52%,
and/or especially less than or equal to 57%.
The alumina A12O3 also constitutes a network former of
the glasses according to the invention and plays a very
important role as regards the hydrolytic resistance of
these glasses. Within the context of the limits defined
according to the invention, reducing the amount of this
oxide to below 10% means that the glass is
substantially more susceptible to hydrolytic attack,
whereas excessively increasing the amount of this oxide

- 8 -
entails the risks of devitrification and an increase in
the viscosity.
The A12O3 content of the selected compositions is
between 10 and 19%, especially greater than or equal to
13%, and/or especially less than or equal to 17%.
The lime (CaO) content of the selected compositions is
less than or equal to 10%, especially less than or
equal to 8%, or even less than or equal to 6%, and/or
preferably greater than or equal to 2%, or even greater
than or equal to 4%.
The magnesia (MgO) content of the selected compositions
is less than or equal to 10%, especially less than or
equal to 8%, or even less than or equal to 6%, and/or
preferably greater than or equal to 2%.
The addition of zirconium oxide (ZrO2) appears to be an
essential point of the invention. The ZrO2 content is
between 0.5 and 1.5%, preferably less than or equal to
1%. This oxide appears to play a very important role in
the dielectric properties, more particularly in the GHz
range as indicated below in the examples. However, the
content must be limited to 1.5% in order to prevent an
unacceptable increase in the liquidus temperature.
The defined limits, in terms of alkaline-earth metal
oxides, lime and magnesia, make it possible to adjust
the viscosity of the glasses according to the
invention. Good fiberizability is obtained by choosing
the sum of these alkaline-earth metal oxides to be
between 4 and 15%, preferably greater than or equal to
6% and/or preferably less than or equal to 10%.
Furthermore, CaO appears to make a beneficial
contribution to the hydrolytic resistance.

- 9 -
Alkali metal oxides, especially Na2O and K20, may be
introduced into the compositions of the glass strands
according to the invention in order to limit
devitrification and possibly reduce the viscosity of
the glass. However, the content of alkali metal oxides
(Na2O + K20 + Li2O) must remain less than or equal to 2%
in order to avoid any deterioration in the dielectric
properties and to avoid a detrimental reduction in the
hydrolytic resistance of the glass. The alkali metal
oxide content is generally greater than 0.1%, due to
the presence of impurities contained in the batch
materials bearing other constituents and it is
preferably less than or equal to 1%, or 0.5% or even
0.3%. The composition may contain a single alkali metal
oxide (from Na2O, K20 and Li2O) or may contain a
combination of at least two alkali metal oxides, the
content of each alkali metal oxide being less than or
equal to 1.5%, preferably less than or equal to 0.8%.
The boron content is between 16 and 25%, preferably
greater than or equal to 18% and/or preferably less
than or equal to 22%, or even less than or equal to
2 0%. According to a preferred version of the invention,
it is desired to limit this oxide to moderate contents
as compared with those of D-glass so as, on the one
hand, not to degrade the hydrolytic resistance, and, on
the other, since the cost of boron-bearing batch
materials is high. Boron may be introduced in a
moderate amount by incorporating, as batch material,
glass strand scrap comprising boron, for example
E-glass strand scrap.
To improve the melting of the glass, fluorine (F) may
be added in a small amount, especially from 0.5 to 2%,
or it may be present as an impurity, especially from
0.1 to 0.5%.
Titanium oxide (TiO2) may also be introduced in an
amount possibly representing up to 3%, preferably less

- 10 -
than 2% or even less than 1%, of the composition. It
allows the viscocity to be lowered without any-
appreciable degradation in the dielectric losses.
The possible Fe2O3 content is rather to be considered as
an impurity content, frequently encountered in this
family of compositions.
In the rest of the text, any percentage of a
constituent of the composition must be understood as a
percentage by weight, and the compositions according to
the invention may include up to 2 or 3% of compounds to
be regarded as unanalyzed impurities (for example SrO,
S03, MnO and MnO2) , as is known in this kind of
composition.
The invention also relates to composites formed from
glass strands and an organic material, in which the
reinforcement is provided at least by the glass strands
of compositions defined above.
Preferably, such glass strands are used for the
manufacture of printed-circuit substrates especially
for forming lightweight fabrics composed of strands
with a diameter of less than or equal to 10 n,
preferably less than or equal to 7 n and
advantageously around 5 m.
The subject of the invention is also a process for
manufacturing glass strands of compositions defined
above, in which a multiplicity of molten glass streams,
flowing out of a multiplicity of orifices placed at the
base of one or more bushings, is drawn in the form of
one or more webs of continuous filaments, and then the
filaments are gathered together into one or more
strands which are collected on a moving support.

- 11 -
Preferably, the molten glass feeding the orifices of
the bushing or bushings has the following composition,
expressed as percentages by weight:
SiO2 50 to 60%, preferably Sio2 ≥ 52% and/or
SiO2 ≤ 57%;
A12O3 10 to 19%, preferably A12O3 ≥ 13% and/or
A12O3 ≤ 17%;
B2O3 16 to 25%;
ZrO2 0.5 to 1.5%;
Na2O ≤ 0.8%;
K2O ≤ 0.8%;
R2O ≤ 1%;
CaO ≤ 10%;
MgO ≤ 10%;
F 0 to 2%;
TiO2 0 to 3%;
RO 4 to 15%, preferably RO ≥ 6% and/or
RO ≤ 10%; and
Various ≤ 3%,
where R2O = Na2O + K2O + Li2O, and RO = CaO + MgO.
It is thus possible to manufacture such glass strands
of small diameter under operating conditions similar to
those for E-glass and D-glass and thus to obtain,
particularly economically, glasses with good dielectric
properties.
The invention also relates to glass compositions
suitable for producing glass reinforcement strands,
comprising the following constituents, within the
limits defined below, expressed as percentages by
weight.
SiO2 50 to 60%, preferably SiO2 ≥ 52% and/or
SiO2 ≤ 57%;
A12O3 10 to 19%, preferably A12O3 ≥ 13% and/or
A12O3 ≤ 17%;
B2O3 16 to 25%;
ZrO2 0.5 to 1.5%;
Na2O ≤ 1.5%, preferably Na2O ≤ 0.8%;

- 12 -
K20 ≤ 1.5%, preferably K20 ≤ 0.8%;
R2O ≤ 2%, preferably R2O ≤ 1%;
CaO ≤ 10%;
MgO ≤ 10%;
F 0 to 2%;
TiO2 0 to 3%;
RO 4 to 15%, preferably RO ≥ 6% and/or
RO ≤ 10%; and
Various ≤ 3%,
where R2O = Na2O + K20 + Li2O, and RO = CaO + MgO.
The advantages afforded by the glass strands according
to the invention will be more fully appreciated through
the following examples, denoted Ex. 1 and Ex. 2, given
in Table 1, illustrating the present invention without
however limiting it.
Comparative examples, denoted A and B, are also given
in Table 1 and correspond to the following glasses:
A: D-glass
B: glass according to patent application WO
99/52833.
In these examples, strands composed of 7 m diameter
glass filaments (examples 1, 2 and B) and 10 m glass
filaments (example A) were obtained by drawing molten
glass; the glass had the composition indicated in
Table 1, expressed in percentages by weight.
When the total sum of the contents of all of the
compounds is slightly less than or greater than 100%,
it should be understood that the residual content
corresponds to the impurities and to minor components
not analyzed (with contents of at most 1 to 2%) and/or
is due to the accepted approximation in this field in
the analytical methods used.

- 13 -
T (log = 3) denotes the temperature at which the
viscosity of the glass is 103 poise (decipascal.second
or dPa.s).
Tlig denotes the liquidus temperature of the glass,
corresponding to the temperature at which the most
refractory phase, which may devitrify in the glass, has
a zero growth rate and thus corresponds to the melting
point of this devitrified phase.
The differences in the dielectric properties (, "}
measured both at 1 MHz and at 9.5 GHz are indicated,
compared with the control A (D-glass).
The measurements at 1 MHz were carried out in a
conventional manner, known to a person skilled in the
art for this type of metrology.
The measurements at 9.5 GHz were carried out according
to the method described by W.B. Westphal ("Distributed
Circuits", in "Dielectric materials and applications",
the Technology Press of MIT and John Wiley & Sons, Inc.
New York, Chapman & Hall, Ltd., London, 1954; see
especially page 69) . The principle of this method is
based on measuring the dielectric properties of a
disk-shaped specimen placed against a waveguide. This
method allows accurate results to be obtained at very
high frequency. In Table 1 is also shown the number of
complete bobbins of strand that are formed per day
under the conditions mentioned above. This number
provides a measure of assessing the comparable
fiberizing yield for the various glasses.
It is apparent that the examples according to the
invention represent a remarkable compromise between the
fiberizing conditions (breakage rate, fiberizing
temperature T (log = 3) and Tlig) and the dielectric
properties.

- 14 -
The fiberizing range is satisfactory, especially with a
difference between T(logT] = 3) and Tliq of greater than or
equal to 180°C.
The dielectric properties of the compositions according
to the invention are of the same order of magnitude as
those of the compositions according to WO 99/52833 for
measurements at 1 MHz and at 9.5 GHz.
Thus, dielectric properties remarkably close to those
of D-glass are obtained, while lowering the fiberizing
temperature of the glasses according to the invention,
compared with that of D-glass.
The glasses according to the invention are also
noteworthy in that they allow small-diameter strands to
be formed with a particularly advantageous yield. Thus,
the number of complete bobbins of strand is greater
with the glasses according to the invention than with
the glasses according to WO 99/52833 (by 36%) for an
identical filament diameter, and considerably higher
(by 300%) than with D-glass, and to be so for a much
smaller diameter (7 urn instead of 10 urn).
Advantageously, the glass strands according to the
invention are suitable for all the usual applications
of conventional E-glass strands and can replace D-glass
strands in some applications. In particular, the glass
strands according to the invention have the advantage
of being able to be obtained with a better yield and a
lower cost than the known glass strands.
Thanks to their fineness and therefore their low linear
density, the glass strands according to the invention
are useful for forming lightweight fabrics exhibiting
good planarity, particularly desirable in electronic
applications.

- 15 -
TABLE 1

Example 1 Example 2 A B
SiO2 55.7 54.7 75.3 54.7
A12O3 15 15.0 0.7 15.0
B2O3 19.4 19.0 19.6 19.9
Na2O 1.8
K20 1.2
R20 0.3 0.3 3.0 0.3
CaO 4.1 4 .0 0.8 4.0
MgO 4.1 4.0 0.4 4.0
TiO2 1.6 2.5
ZrO2 0.9 0.9
F 0.5 0.5 0.5
T (log = 3) CC] 1343 1330 1410 1310
Tliq CO 1150 1150  at 1 MHz
" at 1 MHz (x104)
 at 9.5 GHz
" at 9.5 GHz(x104) + 0.4
0
+ 0.5
+ 150 + 0.4
0
+ 0.6
+ 160 + 0.6
0
+ 0.6
+ 120
Number of complete bobbins 30 30 10 22

- 16 -
CLAIMS
1. A glass reinforcement strand, the composition of
which comprises the following constituents, within the
limits defined below, expressed as percentages by
weight:
SiO2 50 to 60%, preferably SiO2 ≥ 52% and/or
SiO2 ≤ 57%;
A12O3 10 to 19%, preferably A12O3 ≥ 13% and/or
A12O3 ≤ 17%;
B2O3 16 to 25%;
ZrO2 0.5 to 1.5%;
Na2O ≤ 1.5%, preferably Na2O ≤ 0.8%;
K2O ≤ 1.5%, preferably K2O ≤ 0.8%;
R2O ≤ 2%, preferably R2O ≤ 1%;
CaO ≤ 10%;
MgO ≤ 10%;
F 0 to 2%;
TiO2 0 to 3%;
RO 4 to 15%, preferably RO ≥ 6% and/or
RO ≤ 10%; and
Various ≤ 3%,
where R2O = Na2O + K20 + Li2O, and RO = CaO + MgO.
2. The glass strand as claimed in claim 1,
characterized in that . the composition has a ZrO2
content such that ZrO2 ≤ 1%.
3. The glass strand as claimed in one of the
preceding claims, characterized in that the composition
has a lime (CaO) content such that CaO ≤ 8%, or even
CaO ≤ 6% and/or CaO ≥ 2%, or even CaO ≥ 4%.
4. The glass strand as claimed in one of the
preceding claims, characterized in that the composition
has a magnesia (MgO) content such that MgO ≤ 8%, or
even MgO ≤ 6% and/or MgO ≥ 2%.

- 17 -
5. The glass strand as claimed in one of the
preceding claims, characterized in that the composition
has a boron (B2O3) content such that B2O3 ≥ 18% and/or
B2O3 ≤ 22%, or even B2O3 ≤ 20%.
6. A composite of glass strands and organic and/or
inorganic material(s), characterized in that it
comprises glass strands as defined by one of claims 1
to 5.
7. The use of the glass strands defined by one of
claims 1 to 5 for the manufacture of printed-circuit
substrates.
8. A process for manufacturing glass strands as
defined in one of claims 1 to 5, in which a
multiplicity of molten glass streams, flowing out of a
multiplicity of orifices located at the base of one or
more bushings, is drawn in the form of one or more webs
of continuous filaments and then the filaments are
gathered together into one or more strands which are
collected on a moving support.
9. The process as claimed in claim 8, characterized
in that the molten glass feeding the orifices of the
bushing or bushings has the following composition,
expressed as percentages by weight:
SiO2 50 to 60%, preferably SiO2 ≥ 52% and/or
SiO2 ≤ 57%;
A12O3 10 to 19%, preferably A12O3 ≥ 13% and/or
A12O3 ≤ 17%;
B2O3 16 to 25%;
ZrO2 0.5 to 1.5%;
Na2O ≤ 1.5%, preferably Na2O ≤ 0.8%;
K2O ≤ 1.5%, preferably K2O ≤ 0.8%,
R2O ≤ 2%, preferably R2O ≤ 1%;
CaO ≤ 10%;
MgO ≤ 10%;
F 0 to 2%;

- 18 -
TiO2 0 to 3%;
RO 4 to 15%, preferably RO ≥ 6% and/or
RO ≤ 10%; and
Various ≤ 3%,
where R2O = Na2O + K2O + Li2O, and RO = CaO + MgO.
10. A glass composition suitable for producing glass
reinforcement strands, comprising the following
constituents, within the limits defined below,
expressed as percentages by weight:
SiO2 50 to 60%, preferably SiO2 ≥ 52% and/or
SiO2 ≤ 57%;
A12O3 10 to 19%, preferably A12O3 ≥ 13% and/or
A12O3 ≤ 17%;
B2O3 16 to 25%;
ZrO2 0.5 to 1.5%;
Na2O ≤ 1.5%, preferably Na2O ≤ 0.8%;
K2O ≤ 1.5%, preferably K2O ≤ 0.8%;
R2O ≤ 2%, preferably R2O ≤ 1%;
CaO ≤ 10%;
MgO ≤ 10%;
F 0 to 2%;
TiO2 0 to 3%;
RO 4 to 15%, preferably RO ≥ 6% and/or
RO ≤ 10%; and
Various ≤ 3%,
where R2O = Na2O + K20 + Li2O, and RO = CaO + MgO.

Glass reinforcement strand, the composition of which
comprises the following constituents, within the limits
defined below, expressed as percentages by weight:
SiO2 5O to 60%, preferably SiO2 ≥ 52% and/or
SiO2 ≤ 57%
Al2O3 10 to 19%, preferably A12O3 ≥ 13% and/or
Al2O3 ≤ 17%;
B2O3 16 to 25%;
ZrO2 0.5 to 1.5%;
Na2O ≤ 1.5%, preferably Na2O ≤ 0.8%;
K2O ≤ 1.5%, preferably K2O ≤ 0.8%;
R2O ≤ 2%, preferably R2O ≤ 1%?
CaO ≤ 10%;
MgO ≤ 10%;
F 0 to 2%;
TiO2 0 to 3%;
RO 4 to 15%, preferably RO ≥ 6% and/or
RO ≤ 10%; and
Various ≤ 3%,
where R2O - Na2O + K2O + Li2O, and RO = CaO + MgO.
The dielectric properties of such glass compositions
are particularly advantageous in the MHz and GHz
ranges.

Documents:

01696-kolnp-2005-abstract.pdf

01696-kolnp-2005-claims.pdf

01696-kolnp-2005-description complete.pdf

01696-kolnp-2005-form 1.pdf

01696-kolnp-2005-form 2.pdf

01696-kolnp-2005-form 3.pdf

01696-kolnp-2005-form 5.pdf

01696-kolnp-2005-international publication.pdf

1696-kolnp-2005-granted-abstract.pdf

1696-kolnp-2005-granted-claims.pdf

1696-kolnp-2005-granted-correspondence.pdf

1696-kolnp-2005-granted-description (complete).pdf

1696-kolnp-2005-granted-examination report.pdf

1696-kolnp-2005-granted-form 1.pdf

1696-kolnp-2005-granted-form 18.pdf

1696-kolnp-2005-granted-form 2.pdf

1696-kolnp-2005-granted-form 3.pdf

1696-kolnp-2005-granted-form 5.pdf

1696-kolnp-2005-granted-gpa.pdf

1696-kolnp-2005-granted-reply to examination report.pdf

1696-kolnp-2005-granted-specification.pdf

1696-kolnp-2005-granted-translated copy of priority document.pdf


Patent Number 235901
Indian Patent Application Number 1696/KOLNP/2005
PG Journal Number 36/2009
Publication Date 04-Sep-2009
Grant Date 03-Sep-2009
Date of Filing 25-Aug-2005
Name of Patentee SAINT-GOBAIN VETROTEX FRANCE, S. A.
Applicant Address 130 AVENUE DES FOLLAZ, F-73000 CHAMBERY
Inventors:
# Inventor's Name Inventor's Address
1 CREUX, SOPHIE JORDANIESTRAT 4, NL-2622 HT DELFT
2 LECOMTE, EMMANUEL 6, RUE HECTOR BERLIOZ, F-93000 BOBIGNY FRANCE
3 RENAUD, NICOLAS 38, CHEMIN DES PRES, F-73000 BARBERAZ
PCT International Classification Number C03C
PCT International Application Number PCT/FR2004/000568
PCT International Filing date 2004-03-10
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 03/03206 2003-03-13 France