Title of Invention

ELECTRICALLY CONDUCTING GLASS STRANDS AND STRUCTURES COMPRISING SUCH STRANDS

Abstract Glass strand or glass strand structure coated with an electrically conducting coating composition which comprises (as % by weight of solid matter): - 6 to 50% of a film-forming agent, preferably 6 to 45%, - 5 to 40% of at least one compound chosen from plasticizing agents, surface-active agents and/or dispersing agents, - 20 to 75% of electrically conducting particles consisting in a mixture of graphite particles and carbon black particles having a particle size of less than or equal to 1 µm, at least 15% of the said particles having a flake or needle shape, - 0 to 10% of a doping agent, - 0 to 10% of a thickening agent, - 0 to 15% of additives.
Full Text

ELECTRICALLY CONDUCTING GLASS STRANDS AND STRUCTURES
COMPRISING SUCH STRANDS
The present invention relates to glass strands
comprising an electrically conducting coating.
It also relates to the electrically conducting
coating composition used to coat the said strands, to
the process for the manufacture of these strands, to
the reinforcing structures formed from these strands
and to the composite materials including these strands.
Reinforcing glass strands are conventionally
prepared by mechanically drawing molten glass streams
flowing by gravity from the multiple orifices of
bushings filled with molten glass, to form filaments
which are gathered together into base strands, which
strands are then collected.
During the drawing, and before they are
gathered together into strands, the glass filaments are
coated with a sizing composition, generally an aqueous
sizing composition, by passing over a sizing member.
The role of the size is essential in two
respects.
During the manufacture of the strands, it
protects the filaments from the abrasion resulting from
the rubbing of the latter at high speed over the
members of the process, acting as a lubricant. It also
makes it possible to remove the electrostatic charges
generating during this rubbing. Finally, it gives
cohesion to the strand by providing bonding of the
filaments to one another.
During the use for the purpose of producing
composite materials, the size improves the wetting of
the glass and the impregnation of the strand by the
matrix to be reinforced and it promotes the adhesion
between the glass and the said matrix, thus resulting
in composite materials with improved mechanical
properties.
The glass strands in their various forms
(continuous, chopped or milled strands, mats, grids,

fabrics, and the like) are commonly used to effectively
reinforce matrices of varied natures, for example
thermoplastic or thermosetting materials and cement.
Generally, the glass strands are rendered
conducting by the application of a coating based on
particles capable of conducting the electrical current.
The coating is obtained by depositing, on the strands
coated with the size, the conducting particles in
dispersion or in suspension in an aqueous medium and by
removing the water by heating at an appropriate
temperature.
The compositions known for the preparation of
the abovementioned coating use, as conducting
particles, graphite, carbon black or organometallic
compounds capable of decomposing to give metals under
the action of heat, if appropriate by introducing a
carbon-comprising compound capable of giving carbon by
thermal decomposition into the composition
(US-A-3 269 883) or into the size (US-A-3 247 020).
In US-A-4 090 984, use is made of a semi-
conducting coating composition comprising at least one
polyacrylate emulsion, one carbon black dispersion and
one thixotropic gelling agent. The carbon black
dispersion represents 20 to 40 parts per 100 parts of
the composition. In example 1, the content of carbon
black is equal to 11.9% by weight of the solid matter
present in the composition.
In US-A-4 209 425, the coating composition
comprises conducting particles, in particular made of
graphite or of carbon, at least one surfactant, one
thixotrophic gelling agent and optionally one
organosilane coupling agent and/or one antifoaming
agent. The content of conducting particles in the
composition is between 5 and 15% by weight of solid
matter of the composition.
With the compositions which have just been
mentioned, the content of conducting particles in the
final coating remains low, resulting for this reason in
a low level of electrical conductivity.

Recent times have seen the appearance of novel
materials incorporating glass strands which exhibit
high electrical conductivity properties and which can
for this reason be heated by the Joule effect. These
materials include in particular composite materials
with an organic matrix, of the thermoplastic or
thermosetting polymer type, or cement matrix, in which
materials the abovementioned strands also play a
reinforcing role.
The improvement in the electrical conductivity
must not be made at the expense of the other
properties. As regards the composite materials, it must
in particular be kept in mind that the strands are
above all intended to reinforce matrices and
consequently they must exhibit all the qualities for
this.
In particular, the conducting coating must:
- provide bonding of the filaments to one
another and also bond the strands so as to
obtain acceptable or improved mechanical
properties when composite materials are
concerned,
- protect the glass strands from the mechanical
assaults which occur when the reinforcing
structures are employed on building sites,
- protect the glass strands from chemical
corrosion and from assaults related to the
environment, so as to provide satisfactory
durability, and
- provide good bonding with the polymer matrix
to be reinforced, that is to say render the
strands and the matrix compatible.
A subject-matter of the present invention is
glass strands and structures incorporating glass
strands provided with a coating which exhibits a high
electrical conductivity and which are in addition
capable of meeting the requirements related to
reinforcement which are mentioned above.
Another subject-matter of the invention is the

electrically conducting aqueous coating composition
used to coat the abovementioned glass strands and
structures.
Another subject-matter of the invention is a
process for the manufacture of the glass strands and
glass strand structures capable of conducting the
electrical current.
A further subject-matter of the invention is
the composite materials comprising a matrix reinforced
by the abovementioned strands or structures capable of
conducting electricity.
The glass strands and the glass strand
structures in accordance with the invention are coated
with an electrically conducting coating composition
which comprises (as % by weight of solid matter):
- 6 to 50% of a film-forming agent, preferably
6 to 45%,
- 5 to 40% of at least one compound chosen from
plasticizing agents, surface-active agents
and/or dispersing agents,
- 20 to 75% of electrically conducting
particles,
- 0 to 10% of a doping agent,
- 0 to 10% of a thickening agent,
- 0 to 15% of additives.
In the context of the invention, the term
"glass strands" is understood to mean both the base
strands obtained by gathering together, without
twisting, a multitude of filaments under the bushing,
and the assemblages of these strands, in particular in
the form of rovings, and the strands which have been
subjected to a twisting operation, and the assemblages
of these strands. In the glass strands in accordance
with the invention, the filaments are coated with a
sizing composition compatible in particular with the
film-forming agent of the conducting coating. The
electrically conducting coating will thus be
superimposed on the size already present on the strand,
which means that the application of this coating can be

likened to a coating operation.
Sill in the same context, the term "strand
structures" is understood to mean structures obtained
by gathering together intertwined strands, for example
fabrics, or nonintertwined strands, for example
nonwovens, in the form of a mat or veil of continuous
strands, and grids.
The film-forming agent in accordance with the
invention plays several roles: it confers mechanical
cohesion on the coating by causing the conducting
particles to adhere to the glass strand and by
providing bonding of these particles to one another, if
appropriate with the material to be reinforced; it
contributes to bonding the filaments to one another;
finally, it protects the strands against mechanical
damage and chemical and environmental assaults.
The film-forming agent is generally a polymer,
preferably with an elastomeric nature, so as to give
flexibility to the strands. Flexible strands prove to
be particularly advantageous in the production of
structures which can be collected in the form of a
wound package and which are highly "conformable", that
is to say which are capable of matching virtually
perfectly the most diverse shapes.
The film-forming agent can, for example, be
chosen from polyvinylpyrrolidones, poly(vinyl
alcohoDs, polyacrylics (homopolymers or copolymers),
styrene polymers, for example of the styrene-butadiene
(SBR) type, poly(vinyl chloride)s (in particular in the
latex or plastisol form), polyurethanes and the blends
of these polymers. Generally, thermoplastic polyolefins
are avoided as a result of their electrically
insulating nature and their high creep capability.
The choice of the polymer also depends on the
nature of the matrix to be reinforced. As regards
cementing materials, polyacrylics, styrene polymers and
poly(vinyl chloride)s are preferred.
When the content of film-forming agent is less
than 6% by weight of solid materials, the cohesion of

the coating is inadequate. Above 50%, in particular
45%, the amount of conducting particles to be intro-
duced is too low to achieve a satisfactory level of
electrical conductivity. Preferably, the amount of
film-forming agent in the coating represents 10 to 35%
by weight of the solid matter and better still 15 to
35%.
The plasticizing agent makes it possible to
lower the glass transition temperature of the film-
forming agent to a value of the order of 2 0°C, which
makes the coating more flexible, and also makes it
possible to limit the shrinkage after the heat
treatment. The polymers obtained by copolymerization of
butadiene and of an acrylic monomer are preferred.
The amount of plasticizing agent in the coating
generally represents 0 to 15% by weight of the solid
matter, preferably 0 to 10% and better still 3 to 10%.
The surface-active agents improve the suspen-
sion and the dispersion of the conducting particles and
promote compatibility between the other constituents
and the water. It is preferable to use cationic or
nonionic surfactants, in order to avoid problems of
stability of the coating composition and of
nonhomogeneous dispersion of the particles.
The amount of surface-active agent in the
coating generally represents less than 10% by weight of
the solid matter, preferably 0.5 to 10%.
The dispersing agents help in dispersing the
conducting particles in the water and reduce their
separation on settling.
The amount of dispersing agent in the coating
generally represents 2 to 20% by weight of the solid
matter, preferably 3 to 10%.
The plasticizing, surface-active and dispersing
agents can have one or more of the functions specific
to each of the categories mentioned above. The choice
of these agents and of the amount to be used depends on
the film-forming agents and on the conducting
particles.

These agents can in particular be chosen from:
organic compounds, in particular
- optionally halogenated, aliphatic or
aromatic, polyalkoxylated compounds, such as
ethoxylated/propoxylated alkylphenols, pre-
ferably including 1 to 3 0 ethylene oxide
groups and 0 to 15 propylene oxide groups,
ethoxylated/propoxylated bisphenols, prefer-
ably including 1 to 4 0 ethylene oxide groups
and 0 to 2 0 propylene oxide groups, or
ethoxylated/propoxylated fatty alcohols, the
alkyl chain of which preferably comprises 8
to 20 carbon atoms and including 2 to
50 ethylene oxide groups and up to 20
propylene oxide groups. These polyalkoxylated
compounds can be block or random copolymers,
- polyalkoxylated fatty acid esters, for
example polyethylene glycol fatty acid
esters, the alkyl chain of which preferably
comprises 8 to 2 0 carbon atoms including 2 to
50 ethylene oxide groups and up to 2 0
propylene oxide groups,
- amino compounds, for example amines, which
are optionally alkoxylated, amine oxides or
alkylamides, sodium, potassium or ammonium
succinates and taurates, sugar derivatives,
in particular sorbitan derivatives, sodium,
potassium or ammonium alkyl sulphates and
alkyl phosphates, and polyether phosphates,
inorganic compounds, for example silica
derivatives, it being possible for these compounds to
be used alone or as a blend with the abovementioned
organic compounds.
If the total amount of plasticizing, surface-
active and dispersing agents is less than 5%, poor
dispersion of the conducting particles (presence of
aggregates) and/or phase separation is/are observed.
When the content exceeds 40%, a serious decline in the
mechanical performance occurs.

The electrically conducting particles make it
possible to confer electrical conductivity on the glass
strands. In accordance with the invention, these are
carbon-based particles, in particular graphite and/or
carbon black particles.
Whether the graphite is natural or synthetic in
origin has no effect on the electrical conductivity. It
is thus possible to use without distinction either type
of graphite, alone or as a mixture.
The particles can have any shape, for example
the shape of a sphere, flake or needle. Nevertheless,
it has been found that the electrical conductivity of a
mixture of particles of different shapes is improved
with respect to the same amount of particles of
identical shape. Preferably, 30 to 60% of the
conducting particles have a high aspect ratio (defined
by the ratio of the greatest dimension to the smallest
dimension) preferably varying from 5 to 20, in
particular of the order of 10, and advantageously at
least 15% of the particles are provided in the flake or
needle shape.
As well as the shape, the size of the particles
is an important parameter from the viewpoint of the
electrical conductivity. As a general rule, the size of
the particles, taken in their greatest dimension, does
not exceed 250 µm, preferably 100 µm.
Advantageously, the abovementioned particles,
generally made of graphite, are combined with an
electrically conducting carbon black powder with a
particle size of less than or equal to 1 µm, preferably
exhibiting a mean size of between 50 and 100 nm. The
carbon black particles, as a result of their small
size, make it possible to create contact points between
the graphite particles, which makes it possible to
further improve the electrical conductivity.
Preferably, the conducting coating composition
comprises (as % by weight of solid matter):
- 2.5 to 45% and better still 15 to 40% of
graphite particles having a size of between

10 and 100 µm, at least 5% by weight of these
particles being provided in the form of
flakes or needles with an aspect ratio of
greater than or equal to 5,
- 0 to 45%, preferably 5 to 25%, of graphite
particles with a size of less than 10 µm,
preferably having a mean size of the order of
4 µm,
- 2.5 to 45%, preferably 15 to 40%, of carbon
black particles having a size of less than
1 µm.
As already indicated, the amount of conducting
particles represents 20 to 75% of the weight of the
solid matter of the coating. If the content is less
than 20%, there is no electrical conduction as the
percolation threshold is not reached. When the content
exceeds 75%, a portion of the particles no longer
adheres to the glass strand.
The doping agent makes it possible to increase
the conductivity by contributing free electrons or by
promoting delocalization of the electrons.
The doping agent is chosen from organic salts,
such as ammonium crotonate, lithium dodecyl sulphate
and copper acetylacetonate, or inorganic salts, such as
ammonium polyphosphate, titanium chloride or zinc
chloride. Preferably, ammonium crotonate is used.
The doping agent advantageously represents less
than 5% of the weight of solid matter of the coating.
Nevertheless, owing to the fact that the increase in
conductivity remains low with respect to the amount
introduced and that problems of resistance to ageing
may occur, it is preferable to limit the content of
doping agent to 1%. In the majority of cases, no doping
agent is added.
The thickening agent makes it possible to
adjust the viscosity of the coating composition to the
conditions of application to the strand by stabilizing
the dispersion of the particles so as to prevent them
from settling on standing, thus making possible the

deposition of the desired amount on the strand.
The thickening agent is chosen from strongly
hydrophilic compounds, such as carboxymethylcelluloses,
gums, for example guar or xanthan gums, alginates,
polyacrylics, polyamides and the blends of these
compounds.
The amount of thickening agent, when it is
used, varies according to the nature of the compound
(the grade, in the case of the carboxymethyl-
celluloses) .
Preferably, the content of thickening agent is
less than 10% by weight of the solid matter of the
coating.
The conducting coating can also comprise the
usual additives for glass strands, in particular
adhesion promoters, which make it possible to improve
the coupling between the glass and the material to be
reinforced, such as silanes, lubricating and/or
antifoaming agents, such as mineral oils, fatty esters,
for example isopropyl palmitate and butyl stearate, or
organic polymers, or complexing agents, such as
derivatives of EDTA or of gallic acid.
Preferably, the total amount of additives is
less than 10% by weight of the solid matter of the
coating.
The conducting coating composition capable of
coating the glass strands in accordance with the
invention comprises abovementioned constituents and
water.
The content of water in the coating composition
depends on the conditions of application, in particular
on the viscosity and on the content of conducting
particles to be deposited. As a general rule, the
amount of water is determined so as to obtain a
viscosity of greater than or equal to 190 mPa•s,
preferably of less than 40 000 mPa-s, advantageously of
less than 20 000 mPa•s, better still of less than
10 000 mPa•s, in particular of less than or equal to
5400 mPa•s.

The composition is prepared conventionally by-
introducing the various constituents in the aqueous
medium, preferably individually, with sufficient
stirring to keep the conducting particles in dispersion
or in suspension.
When a thickening agent is used, it is
introduced first in the form of an aqueous solution,
preferably heated to approximately 80°C in order to
dissolve better.
Generally, the coating composition is used
virtually immediately after having been prepared but it
can also be used after a storage period of approxi-
mately six months at a temperature of 20 to 25°C. If
appropriate, vigorous stirring makes it possible to
redisperse the particles which have separated by
settling, without this affecting the qualities of the
composition.
In accordance with the invention, the process
for the manufacture of the glass strands and of the
strand structures coated with the electrically
conducting coating comprises the stages consisting in:
coating glass strands or glass strand
structures with the abovementioned conduct-
ing coating composition, and
heating the said strands or the said
structures, thus coated, at a temperature
sufficient to remove the water and to
strengthen the conducting coating.
The composition is applied to glass strands at
various stages of the process after fiberizing,
preferably to strands originating from wound packages,
for example rovings, or to structures in which the
strands are gathered together in various ways: by
superimposition of continuous strands deposited in a
random manner (mat or veil) or ordered manner (grid) or
by weaving with intertwining of the strands.
According to a preferred embodiment, the
coating of the strand or of the strand structure is
carried out by immersion in a bath of the conducting

coating composition. In the bath, the strand or the
structure passes into a device which makes it possible
to control the amount of coating composition to be
deposited.
In the case of strands, the device can be a
bushing positioned in the bath, preferably a conical
bushing, the angle of the cone of which is defined so
that the strand entering via the biggest opening can be
coated by the composition in a uniform way over the
whole of its surface.
As regards strand structures, the device can be
a padding machine, of the type used in the textile
industry, positioned at the outlet of the bath.
Optionally, before passing through the bushing
or over the padding machine, the strand or the
structure can pass over a device targeted at "opening"
the strands and making possible better impregnation of
the filaments. This device can be composed of one or
more series of bars forming turn rolls, in the case of
the treatment of the strand, or of a series of rollers,
for the treatment of strand structures.
At the outlet of the bath, the strand or the
structure is treated thermally to remove the water and
to strengthen the coating. As a general rule, the
treatment temperature is greater than approximately
105°C and less than approximately 220°C, preferably
less than 160°C. To prevent blistering of the coating
brought about by rapid removal of the water, it is
preferable to heat the strand or the structure at a
temperature close to the minimum temperature indicated,
if need be while increasing the duration of treatment,
or to carry out the treatment continuously over the
complete temperature range in successive stationary
phases or with a temperature gradient. Preferably, the
maximum temperature remains less than approximately
150°C, and better still less than 130°C.
Any appropriate heating device can be used for
this, for example an infrared oven or a device which
makes it possible to heat the strand or the structure

by contact, for example a device composed of one or
more rotary heating drums.
The temperature and the duration of the
treatment are chosen according to the type of device
used so as to obtain a strengthened coating. By way of
indication, the treatment in an oven can be carried out
satisfactorily at a temperature of the order of 105°C
for a time which generally does not exceed 3 hours.
After the heat treatment, the glass strand is
collected, for example in the form of wound packages,
or else it is deposited on a translationally moving
receiving support to form a mat.
The glass strand and the strand structure in
accordance with the invention are characterized in that
they have electrical conduction properties while having
the qualities specific to providing a reinforcing
function. The strand and the structure are noteworthy
in that the amount of conducting coating can represent
up to 200% of their total weight, more generally of the
order of 20 to 60%, and that this relatively high
content of conducting particles confers thereon an
altogether advantageous level of performance. An
assessment of this level is given by the value of the
volume electrical resistivity (equal to the inverse of
the volume electrical conductivity), which is a
standard reference term in the field of conducting
strands. The volume electrical resistivity of the
strand according to the invention is less than
1000 Ω.cm, preferably 100 Ω.cm, advantageously 10 Ω.cm
and better still 1 Ω.cm. The strands and the structures
exhibiting a volume electrical resistivity varying from
10 to 100 Ω.cm can be used for Joule effect heating.
Those for which the said resistivity is less than or
equal to 1 Ω.cm are more particularly suitable for
electromagnetic shielding.
The conducting strand and the strands which are
constituents of the structure in accordance with the
invention can be made of any kind of glass, for example
E-, C-, R- and AR-glass. E-glass is preferred.

The diameter of the glass filaments constitut-
ing the strands can vary to a large extent, for example
from 5 to 30 µm. In the same way, large variations can
occur in the weight per unit length of the strand,
which can range from 68 to 2400 tex according to the
applications targeted.
The conducting glass strand and the conducting
structures in accordance with the invention can be used
to reinforce various materials and thus to form
conducting composite materials capable in particular of
being heated by the Joule effect. As has already been
said, such composite materials can be used for the
heating of buildings or the de-icing of roads, bridges
or landing runways.
The structures can, as such, act as electro-
magnetic shielding or heating elements applied at the
surface or incorporated in wall faces or the ground.
As shielding elements, the purpose of the
structures is to weaken electromagnetic waves harmful
to the satisfactory operation of electronic devices or
to limit, indeed even prevent, the use of portable
telephones in certain public or private places
(hospitals, cinemas, prisons, and the like).
Structures in the form of grids can be
incorporated in particular in structures, for example
bridges, to limit battery effects related to the
presence of metal components which increase the risks
of corrosion.
The examples given below make it possible to
illustrate the invention without, however, limiting it.
In these examples, the following methods are
used:
> The loss on ignition is measured in the
following way: a predetermined amount (approximately
1 gram) of cut strands is introduced into a porcelain
crucible (weight W1). The crucible is heated in an oven
at 105°C for 1 hour to evaporate the adsorbed water. On
removal from the oven and after cooling, the crucible
is weighed (weight W2) and is then heated in an oven at

700°C for 5 hours. The crucible is weighed on removal
from the oven after cooling under anhydrous conditions
(weight W3).
The loss on ignition is equal to: W2-W3/W2-W1.
The tensile strength of the strands is
measured under the following conditions.
The ends of a roving of a 2000 tex base strand,
with a length of 240 mm, are placed between flat
clamping jaws lined with Vulcolan over a distance of
7 0 mm. The roving is drawn at the rate of 100 mm/min
until it breaks. The strength is expressed in MPa.
The volume resistivity is obtained by the
calculation from the relationship:
ρ = R x S/1
in which ρ is the resistivity in Ω.cm,
R is the resistance in Ω,
S is the cross section of the
strand in cm2,
1 is the length of the fibre in
cm.
The resistance R is measured using an ohmmeter,
the distance between the two electrodes being 20 cm.
> The electromagnetic shielding, in dB, is
measured under the conditions of Standard MIL-STD-285
(27 June 1956) between 100 MHz and 2.7 GHz.
EXAMPLE 1
a) Preparation of the coating composition
A composition is prepared comprising (as % by
weight of solid matter):
- film-forming agent: polyvinylpyrrolidone(1) 20
- thickening agent: carboxymethycellulose(2) 2
- plasticizers:

• bisphenol A bis(polyethylene glycol) 16.5
ether(3)
• octylphenoxypoly (ethyleneoxy) ethanol(4) 8.5
- cationic dispersant(5) 3
conducting particles
• natural graphite powder(6) (mean size of 30
the particles: 3 µm)

• expanded synthetic graphite(7) in the 10
form of flakes (size of the particles:
10-50 µm)
• natural graphite powder(8) (mean size of 10
the particles: 5 µm)
The composition is prepared by addition of the
constituents to a receptacle containing water at 80°C
which is kept vigorously stirred, the thickening agent
being introduced first and the conducting particles
last.
The viscosity of the composition is 3800 mPa•s
at 20°C.
b) Production of the glass strand
A glass strand composed of 4000 filaments with
a diameter of 15.8 urn (weight per unit length:
2000 tex) unwound from a roving is immersed in a bath
of the composition obtained under a). The strand enters
the bath via a strand guide at the rate of 2.5 m/min,
subsequently passes through a conical bushing (small
diameter: 2.2 mm) and, at the outlet of the bath, is
wound onto a frame rotating around an axis. The frame
is placed in an oven heated at 105°C for 3 hours.
The strand exhibits the following
characteristics:
Loss on ignition: 21.0%
Resistivity: 7.8 Ω.cm (standard deviation:

2.3)
Tensile strength: 863 MPa (standard
deviation: 23)
EXAMPLE 2
The operation is carried out under the
conditions of Example 1, the conducting coating com-
position comprising (in % by weight of solid matter):

film-forming agent :polyvinylpyrrolidone(1) 20
thickening agent: carboxymethylcellulose(2) 2
plasticizers:
• bisphenol A bis(polyethylene glycol) 16
ether(3)
• octylphenoxypoly(ethyleneoxy)ethanol(4) 7
cationic dispersant(5) 5
conducting particles
• natural graphite powder(6) (mean size 25
of the particles: 3 µm)
• expanded synthetic graphite(7) in the form 15
of flakes (size of particles: 10-50 µm)
• synthetic graphite powder(9) (mean size of
the particles: 10 µm) 10
The viscosity of the composition is 5400 mPa•s
at 20°C.
The strand exhibits a loss on ignition of
20.0%.
The resistivity and tensile strength measure-
ments of the strand before and after accelerated ageing
are as follows (the standard deviation is given in
brackets):
Time (days) t=0 t=1 t=14
Resistivity (Ω.cm) 1.55 (0.4) 1.7 (0.2) 1.8 (0.2)
Tensile strength (MPa) 1130 (62) 1044 (50) 950 (78)
After ageing for 14 days, the resistivity is
substantially unchanged and the tensile strength is
equal to 84% of its initial value.
EXAMPLES 3 AND 4
These examples illustrate the effect of amount
of conducting particles of high aspect ratio on the
resistivity.
The operation is carried out under the
conditions of Example 1, modified in that the following
compositions are used (in % by weight of solid matter):

film-forming agent: polyvinyl- 2 0.0
pyrrol idone(1)
thickening agent: carboxymethyl- 2.00
cellulose(2)
plasticizers:
• bisphenol A bis(polyethylene glycol) 10.25
ether(3)
• octylphenoxypoly(ethyleneoxy) 10.25
ethanol(4)
cationic dispersant(5) 7.50
conducting particles
• graphite powder(10) in the form of Ex.3 Ex.4
flakes (size of the particles:
10-50 urn) 2.5 15.0
• synthetic graphite powder(9) (mean
size of the particles: 10 µm) 47.5 35.0
The viscosities of the compositions are
4900 mPa•s and 5400 mPa•s respectively at 20°C.
The strands obtained exhibit the following
characteristics (the standard deviation is given in
brackets):
Ex. 3 Ex. 4
Loss on ignition (%) 20.4 19.8
Resistivity (Ω.cm) 2.9 (0.8) 2.3 (0.3)
Tensile strength (MPa) 1320 (115) 1348 (58)
It is found that an increase in the relative
proportion of particles in the form of flakes, at an
equivalent total amount of particles, makes it possible
to reduce the resistivity and thus to increase the
electrical conductivity.
EXAMPLE 5
The operation is carried out under the
conditions of Example 1, modified in that the strand is
composed of 800 filaments with a diameter of 13.6 urn
(weight per unit length: 300 tex), that the small
diameter of the bushing is equal to 1.2 mm and that the
conducting coating composition comprises (as % by

weight of solid matter):
film-forming agent: polyvinylpyrrolidone(1) 20.0
thickening agent: carboxymethylcellulose(2) 2.0
plasticizers:
• bisphenol A bis(polyethylene glycol) 17.0
ether(3)
• octylphenoxypoly (ethyleneoxy) ethanol(4) 6.0
nonionic dispersant(11) 5.0
conducting particles
• expanded synthetic graphite(7) in the form 25.0
of flakes (size of the particles:
10-50 µm) 25.0
• carbon black powder(12) (mean size of the
particles: 50 nm)
The viscosity of the composition is 4800 mPa•s
at 20°C.
The strand exhibits the following characteris-
tics (the standard deviation is given in brackets):
> Loss on ignition: 14.4%
> Resistivity: 0.3 Ω.cm (0.04); identical
after storing at 20°C for 15 weeks
> Tensile strength: 1361 (93) MPa.
EXAMPLE 6
The operation is carried out under the
conditions of Example 1, the conducting coating com-
position comprising (as % by weight of solid matter):
film-forming agents:
• acrylic polymer(13) 33.8
• acrylic copolymer(14) 10.0
surfactants:

• 2,4,7, 9-tetramethyl-5-decyn-4,7-diol(15) 0.2
• 10 EO C12-C14 alcohol(16) 1-0
nonionic dispersant(11) 5.0
conducting particles
• expanded synthetic graphite(7) in the 20.0
form of flakes (size of the particles:
10-50 µm)
• synthetic graphite powder(17) (size of 10.0
the particles: 1-10 µm)

• carbon black powder(12) (mean size of 20.0
the particles: 50 µm)
The viscosity of the composition is 590 MPa • s
at 2 0°C.
The strand exhibits a loss on ignition of
42.1%.
The resistivity and the tensile strength of the
strand, before and after accelerated ageing, are given
below (the standard deviation appears in brackets):
Time (days) t = 0 t = 1 t = 3
Resistivity (Ω.cm) 0.18 0.18 0.18
(0.01) (0.03) (0.01)
Tensile strength (MPa) 1876 (115) 1695 (78) 1565 (43)
Time (days) t = 7 t = 14
Resistivity (Ω.cm) 0.17 0.15
(0.02) (0.01)
Tensile strength (MPa) 1503 (158) 1697 (38)
The resistance of the strands under the
accelerated ageing conditions is excellent: the high
level of performance, in particular of the tensile
strength, is maintained over time.
EXAMPLE 7
The operation is carried out under the condi-
tions of Example 1, the conducting coating composition
comprising (as % by weight of solid matter):
film-forming agents:
• acrylic polymer(13) 38.9
• acrylic copolymer(14) 11.5
surfactants:

• 2,4,7, 9-tetramethyl-5-decyn-4,7-diol(15) 0.2
• 10 EO C12-C14 alcohol(16) 1.0
nonionic dispersant(11) 4.4
conducting particles
• expanded synthetic graphite(7) in the 22.0
form of flakes (size of the particles:
10-50 µm)

• carbon black powder(12) (mean size of 22.0
the particles: 50 nm)
The viscosity of the composition is 1820 mPa • s
at 20°C.
The strand exhibits the following
characteristics :
> Loss on ignition: 39.8%
> Resistivity
t = 0 days: 0.17 Ω.cm (standard deviation:
0.01)
t = 14 days: 0.16 Ω.cm (standard deviation:
0.03)
> Tensile strength:
t = 0 days: 1864 MPa (standard deviation:
50)
t = 14 days: 1648 MPa (standard deviation:
72)
EXAMPLE 8
The operation is carried out under the condi-
tions of Example 1, the conducting coating composition
comprising (as % by weight of solid matter):
film-forming agents:
• acrylic polymer(13) 23.8
• acrylic copolymer(14) 20.0
plasticizers/surfactants:
• nonionic surf actant(15) 0.2
• ethoxylated fatty alcohol(16) 1.0
cationic dispersant(5) 5.0
conducting particles
• expanded synthetic graphite(10) in the form 20.0
of flakes (size of the particles:
10-50 urn)
• synthetic graphite powder(17) (size of 10.0
the particles: 1-10 µm)
• carbon black powder(12) (size of the 20.0
particles: 50 nm)
The viscosity of the composition is 190 mPa•s
at 20°C.
The strand exhibits the following

characteristics:
> Loss on ignition: 39.51%
> Resistivity: 0.17 Ω.cm
> Tensile strength: 1673.3 MPa
EXAMPLE 9
This example illustrates the influence of the
amount of coating on the electrical conductivity and
the mechanical properties of the strand..
a) Preparation of the coating composition
A composition is prepared comprising (as % by
weight of solid matter):
film-forming agent:
• styrene-butadiene copolymer(18) 46.5
nonionic dispersant(11) 6.0
antifoaming agent(19) 1.0
conducting particles
• expanded synthetic graphite(7) in the form 18.6
of flakes (size of the particles:
10-50 µm)
• synthetic graphite powder(17) (size of the 9.3
particles: 1-10 µm)
• carbon black powder(12) (size of the 18.6
particles: 50 nm)
The composition is prepared by addition of the
constituents to a receptacle containing water at
ambient temperature (approximately 25°C) with vigorous
stirring, the conducting particles being introduced
last.
The composition exhibits a viscosity of
800 mPa•s at 20°C.
b) Production of the glass strand
The operation is carried out under the
conditions of Example 1, modified in that the glass
strand is composed of 800 filaments with a diameter of
13 µm (weight per unit length: 275 tex).
A variable amount of conducting coating com-
position is deposited on the glass strand (Tests 1 to
3) .

Test 1 Test 2 Test 3
Loss on ignition (%) 21.9 30.6 45.7
Volume resistivity (Ω.cm) 0.23 0.16 0.14
Tensile strength (MPa) 2035 2045 2059
It is found that the volume resistivity-
decreases as a function of the amount of coating
composition deposited on the strand, which means that
the electrical conductivity is increased. At the same
time, the tensile strength level is virtually unchanged
(the increase observed not being significant).
EXAMPLE 10
The operation is carried out under the
conditions of Example 9 while varying the ratio by
weight of the conducting particles (P) to the sum of
the conducting particles (P) and of the film-forming
agent (F). The loss on ignition is between 21 and 23%.
Test P/P+F (%) Volume resistivity (Ω.cm)
1 25 4.11
2 30 1.14
3 35 0.75
4 40 0.42
5 50 0.23
6 60 0.24
For these values, it is deduced that the
percolation threshold (corresponding to the P/P+F ratio
starting from which the strand exhibits a satisfactory
conductivity) is between 30 and 35%.
EXAMPLE 11
a) Preparation of the coating composition
The operation is carried out under the
conditions of Example 9, the coating composition
comprising (as % by weight of solid matter):
film-forming agent:
• styrene-butadiene copolymer(20) 46.5
nonionic dispersant(11) 6.0
antifoaming agent(19) 1.0
conducting particles
• expanded synthetic graphite(7) in the form 18.6
of flakes (size of the particles:

10-50 µm)
• synthetic graphite powder(17) (size of the 9.3
particles: 1-10 µm)
• carbon black powder(12) (size of the 18.6
particles: 50 nm)
The composition exhibits a viscosity of
230 mPa•s at 20°C.
b) Production of the glass fabric
A glass fabric (weight per unit area: 165 g/m2)
exhibiting a square mesh of 3 5 mm and a thickness of
0.4 mm is immersed in a vat with a width of 3 00 mm
filled with the composition obtained under a) . At the
outlet of the vat, the fabric is squeezed by passing
between the two rolls of a calender (pressure: 0.6 bar;
speed of rotation: 0.5 m/min) and then it passes into
an air oven comprising 4 compartments heated at 90°C,
130°C, 150°C and 90°C respectively. The residence time
in each compartment is 2 minutes.
Various tests were carried out with a level of
coating (weight of coating/weight of uncoated fabric)
of 30% (Test 1), 60% (Test 2) and 115% (Test 3).
Several passes through the impregnation bath were
carried out in order to obtain the highest levels
(Tests 2 and 3).
The curve of the electromagnetic shielding as a
function of the frequency is given in Figure 1.
The fabric according to the invention exhibits
a shielding value of greater than 5 dB and of less than
25 dB depending on the level of coating, over the
entire frequency range examined.
It is specified that a shielding value of 10 dB
corresponds to a weakening in the strength of the
electrical field by a factor of 3, a value of 20 dB
corresponds to a weakening by a factor of 10 and a
value of 3 0 dB corresponds to a weakening by a factor
of 30.
Tests 1 to 3 exhibit values of the same order
of magnitude as the available fabrics which are
suitable for electromagnetic shielding. In particular,

the level of performance of Test 2 is comparable with
that which is obtained with a fabric based on copper
wires and on glass strands which are comingled and
provided with a conducting coating and which are
arranged in weft and in warp. However, this fabric is
not entirely satisfactory as, on the one hand, the
contact of the copper wires at the crossing points is
not always assured and, on the other hand, the copper
has a tendency to oxidize to form an insulating surface
layer which results in a reduction in the electrical
conductivity.
EXAMPLE 12
The operation is carried out under the
conditions of Example 11, modified in that the coating
composition comprises (as % by weight of solid matter):
film-forming agent:
• styrene-butadiene copolymer(20) 37.0
nonionic dispersant(11) 7.0
antifoaming agent(19) 1.0
conducting particles
• expanded synthetic graphite(7) 22.0
• synthetic graphite powder(17) 11.0
• carbon black powder(12) 22.0
The composition exhibits a viscosity of
545 mPa•s at 20°C.
The fabric was impregnated with a level of
coating of 32% (Test 1), 64% (Test 2) and 160%
(Test 3) .
The curve of the electromagnetic shielding as a
function of the frequency is given in Figure 2.
It is observed that Tests 1 to 3 exhibit
improved levels of performance in comparison with those
of Example 11.

®
(1) Sold under the reference "Luviskol K 90" by BASF
(2) Sold under the reference "Blanose® 7 MC" by
Aqualon
(3) Sold under the reference "Simulsol® BPPE" by
SEPPIC

(4) Sold under the reference "Antarox® CA 630 by
Rhodia HPCII
(5) Sold under the reference "Solsperse® 20000" by
Avecia
(6) Sold under the reference "GK UF2 96/97" by
Kropfmiilh

(7) Sold under the reference "Grafpower® TG 407" by
Ucar
(8) Sold under the reference "GK UF4 96/97" by
Kropfmulh
(9) Sold under the reference "SPF 16" by Ucar
(10) Sold under the reference "Grafpower® TG 40" by
Ucar

(11) Sold under the reference "Solsperse® 27000" by
Avecia
(12) Sold under the reference "Vulcan® XC 72R" by Cabot
S.A.
(13) Sold under the reference "Latex 651" by Ucar
(14) Sold under the reference "Carboset® 514 W" by
Noveon
(15) Sold under the reference "Surfynol® 104-PA" by Air
Products
(16) Sold under the reference "Simulsol® P10" by SEPPIC
(17) Sold under the reference "SPF 17" by Ucar
(18) Sold under the reference "Styronal® ND430" by BASF

(19) Sold under the reference "Tego Foamex® 83 0" by
Degussa
(20) Sold under the reference "Styronal® D517" by BASF

WE CLAIM:
1. Glass strand or glass strand structure coated with an
electrically conducting coating composition which comprises
(as % by weight of solid matter):
- 6 to 50% of a film-forming agent, preferably 6 to
45%,
- 5 to 40% of at least one compound chosen from
plasticizing agents, surface-active agents and/or
dispersing agents,
- 20 to 75% of electrically conducting particles
consisting in a mixture of graphite particles and
carbon black particles having a particle size of
less than or equal to 1 urn, at least 15% of the
said particles having a flake or needle shape,
- 0 to 10% of a doping agent,
- 0 to 10% of a thickening agent,
- 0 to 15% of additives.
2. Strand or structure as claimed in Claim 1, wherein the
film-forming agent is a polymer, preferably with an
elastomeric nature.

3. Strand or structure as claimed in Claim 2, wherein the
film-forming agent is chosen from polyvinylpyrrolidones,
poly(vinyl alcohol)s, polyacrylics, styrene polymers,
poly(vinyl chloride)s, polyurethanes and the blends of
these polymers.
4. Strand or structure as claimed in one of Claims 1 to
3, wherein the plasticizing, surface-active and/or
dispersing agent is chosen from optionally halogenated,
aliphatic or aromatic, polyalkoxylated compounds, from
polyalkoxylated fatty acid esters, from amino compounds,
from silica derivatives and from the blends of these
compounds.
5. Strand or structure as claimed in Claim 1, wherein the
size of the particles does not exceed 250 µm, preferably
100 µm.
6. Strand or structure as claimed in one of Claims 1 to
5, wherein 30 to 60% of the particles have an aspect ratio
which varies from 5 to 20.

7. Electrically conducting aqueous coating composition
for a glass strand or glass strand structure, wherein it
comprises:
- 6 to 50% of a film-forming agent, preferably 6 to
45%,
- 5 to 40% of at least one compound chosen from
plasticizing agents, surface-active agents and/or
dispersing agents,
- 20 to 75% of electrically conducting particles
consisting in a mixture of graphite particles and
carbon black particles having a particle size of
less than or equal to 1 µm, at least 15% of the
said particles having a flake or needle shape,
- 0 to 10% of a doping agent,
- 0 to 10% of a thickening agent,
- 0 to 15% of additives.
8. Composition as claimed in Claim 7, wherein
it exhibits a viscosity of greater than or equal to 190
mPa•s, preferably of less than 40 000 mPa•s, advantageously
of less than 20 000 mPa•s, better still of less than 10 000
mPa•s, in particular of less than or equal to 5400 mPa•s.

9. Composition as claimed in Claim 8, wherein it
comprises:
- 2.5 to 45% and better still 15 to 40% of graphite
particles having a size of between 10 and 100 µm,
at least 5% by weight of these particles being
provided in the form of flakes or needles with an
aspect ratio of greater than or equal to 5,
- 0 to 45%, preferably 5 to 25%, of graphite
particles with a size of less than 10 µm,
preferably having a mean size of the order of 4
µm,
- 2.5 to 45%, preferably 15 to 40%, of carbon black
particles having a size of less than 1 µm.
10. Process for the preparation of a glass strand or of a
glass strand structure as claimed in Claim 1 which
comprises the stages consisting in
- coating a glass strand or a glass strand
structure with the conducting coating composition
according to one of Claims 1 to 11, and
- heating the said coated strand or the said coated
structure at a temperature sufficient to remove
the water and to strengthen the conducting
coating.

11. Process as claimed in Claim 10, wherein the coating is
carried out by immersion in a bath of the conducting
coating composition.
12. Process as claimed in Claim 10 or 11, wherein the
heating is carried out at a temperature of greater
than approximately 105oC and less than approximately
220°C, preferably less than approximately 160°C.
13. Glass strand structure as claimed in Claim 1, wherein
it is provided in the form of an assemblage of
intertwined strands, for example a fabric, or
nonintertwined strands, for example a nonwoven, such
as a mat or a veil of continuous strands, or a grid.
14. Structure as claimed in Claim 13, wherein it exhibits
an electromagnetic shielding value of between 5 and 50
dB, preferably between 5 and 35 dB, measured between
100 MHz and 2.7 GHz.
15. Composite material comprising a matrix reinforced by
glass strands or a glass strand structure as claimed
in one of Claims 1, 13 or 14.

16. Material as claimed in Claim 15, wherein the matrix is
a thermoplastic or thermosetting polymer or a
cementing material.



ABSTRACT


Title: Electrically conducting glass strands and structures and structures
comprising such strands.
Glass strand or glass strand structure coated with an
electrically conducting coating composition which comprises
(as % by weight of solid matter):
- 6 to 50% of a film-forming agent, preferably 6 to
45%,
- 5 to 40% of at least one compound chosen from
plasticizing agents, surface-active agents and/or
dispersing agents,
- 20 to 75% of electrically conducting particles
consisting in a mixture of graphite particles and
carbon black particles having a particle size of
less than or equal to 1 µm, at least 15% of the
said particles having a flake or needle shape,
- 0 to 10% of a doping agent,
- 0 to 10% of a thickening agent,
- 0 to 15% of additives.

Documents:

02028-kolnp-2006 assignment.pdf

02128-kolnp-2006 abstract.pdf

02128-kolnp-2006 claims.pdf

02128-kolnp-2006 correspondence others.pdf

02128-kolnp-2006 description(complete).pdf

02128-kolnp-2006 drawings.pdf

02128-kolnp-2006 form1.pdf

02128-kolnp-2006 form2.pdf

02128-kolnp-2006 form3.pdf

02128-kolnp-2006 form5.pdf

02128-kolnp-2006 international publication.pdf

02128-kolnp-2006 international serch authority report.pdf

02128-kolnp-2006 pct form.pdf

02128-kolnp-2006 priority document.pdf

02128-kolnp-2006-claims-1.1.pdf

02128-kolnp-2006-correspondence others-1.1.pdf

02128-kolnp-2006-priority document-1.1.pdf

2128-KOLNP-2006-(09-11-201)-PETITION UNDER RULR 137.pdf

2128-KOLNP-2006-(09-11-2011)-ABSTRACT.pdf

2128-KOLNP-2006-(09-11-2011)-AMANDED CLAIMS.pdf

2128-KOLNP-2006-(09-11-2011)-DESCRIPTION (COMPLETE).pdf

2128-KOLNP-2006-(09-11-2011)-DRAWINGS.pdf

2128-KOLNP-2006-(09-11-2011)-EXAMINATION REPORT REPLY RECIEVED.pdf

2128-KOLNP-2006-(09-11-2011)-FORM 1.pdf

2128-KOLNP-2006-(09-11-2011)-FORM 2.pdf

2128-KOLNP-2006-(09-11-2011)-FORM 3.pdf

2128-KOLNP-2006-(09-11-2011)-OTHERS.pdf

2128-KOLNP-2006-(31-01-2012)-CORRESPONDENCE.pdf

2128-KOLNP-2006-CANCELLED PAGES.pdf

2128-KOLNP-2006-CORRESPONDENCE.pdf

2128-KOLNP-2006-EXAMINATION REPORT.pdf

2128-KOLNP-2006-FORM 18.pdf

2128-KOLNP-2006-GPA.pdf

2128-KOLNP-2006-GRANTED-ABSTRACT.pdf

2128-KOLNP-2006-GRANTED-CLAIMS.pdf

2128-KOLNP-2006-GRANTED-DESCRIPTION (COMPLETE).pdf

2128-KOLNP-2006-GRANTED-FORM 1.pdf

2128-KOLNP-2006-GRANTED-FORM 2.pdf

2128-KOLNP-2006-GRANTED-FORM 3.pdf

2128-KOLNP-2006-GRANTED-FORM 5.pdf

2128-KOLNP-2006-GRANTED-SPECIFICATION-COMPLETE.pdf

2128-KOLNP-2006-INTERNATIONAL PUBLICATION.pdf

2128-KOLNP-2006-INTERNATIONAL SEARCH REPORT & OTHERS.pdf

2128-KOLNP-2006-PETITION UNDER RULE 137.pdf

2128-KOLNP-2006-REPLY TO EXAMINATION REPORT.pdf

2128-KOLNP-2006-TRANSLATED COPY OF PRIORITY DOCUMENT.pdf


Patent Number 256150
Indian Patent Application Number 2128/KOLNP/2006
PG Journal Number 19/2013
Publication Date 10-May-2013
Grant Date 08-May-2013
Date of Filing 28-Jul-2006
Name of Patentee SAINT-GOBAIN VETROTEX FRANCE S.A.
Applicant Address 130 AVENUE DES FOLLAZ, F-73000 CHAMBERY FRANCE
Inventors:
# Inventor's Name Inventor's Address
1 MOIREAU , PATRICK VERNAY,73190 CURIENNE,FRANCE
2 CEUGNIET , CLAIRE BASSA,F-37410 SAINT OURS, FRANCE
PCT International Classification Number C03C25/10
PCT International Application Number PCT/FR05/050087
PCT International Filing date 2005-02-11
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 0401426 2004-02-12 France