Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEM AND PROCESS FOR PRODUCING EXPANDED POLYSTYRENE
(EPS) BEADS COATED WITH A COATING COMPOSITION, COMPOSITION
USED THEREFOR, AND A CONCRETE MIXTURE CONTAINING SAME
FIELD OF THE INVENTION
The invention relates to expanded polystyrene particles. In particular, the
invention relates to pre-expanded polystyrene particles having a coating layer
produced by coating the surface of the pre-expanded polystyrene particles with
a
functional coating composition.
BACKGROUND OF THE INVENTION
Expanded polystyrene is a polymer resin obtained by heating and curing
the polystyrene resin to generate foams. Expanded polystyrene is white in
color,
light in weight, and has superior water resistance, thermal insulation, sound
absorption and buffering properties. Due to these advantages, expanded
polystyrene has wide industrial applicability.
A particular application of the expanded polystyrene is construction, in
particular, as an additive for a building material. The introduction of
granules or
beads, for example of polystyrene, into concrete or plaster presents
difficulties,
however, in obtaining adequate binding adherence between the concrete and the
granules. It is a known problem of building materials of this type that the
granules
are easily broken away from the concrete or plaster, with the result that the
material tends to disintegrate as the granules break away.
Previous issues in developing such a mixture were based primarily on the
inability of concrete to adhere to EPS beads, and thus the inability of the
mixture
to blend evenly and produce an evenly distributed mixture that could be
extruded
or cast to form structurally sound, solid construction panels. This was
because
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expanded polystyrene emits a miniscule amount of pentane gas for long periods
of time, covering the bead with a molecular layer of gas which acts as a
release
agent, preventing concrete from properly adhering to beads. This lack of
adherence resulted in poorly mixed lightweight concrete, which was
characterized by, inter alia, bead clumping, bead floating, and non-consistent
consolidation of mix as well as structural weakness and failure, in previous
EPS
and concrete mixtures.
Additional problems associated with prior concrete construction are: tests,
studies and time, have shown that water causes shrinkage and cracks in
concrete.
Expanded polystyrene beads coated with a functional layer and
manufacturing processes thereof are known in the art.
For instance, U.S. Patent No. 3,257,338 issued June 21, 1966 to Sefton
relates to lightweight construction material, particularly to lightweight
concrete.
Sefton describes a concrete mix comprising cement, primary aggregate and/or
filler, expanded, expandable polystyrene, and a homogenizing agent. The
expanded polystyrene are made from particles of expandable styrene polymer
and are preferably, but not limited to, spherical beads.
U.S. Patent No. 3,764,357 issued October 9, 1973, to Bowles et al.,
discloses a method of preparation of lightweight concrete and plaster
comprising
the steps of : wetting the surfaces of lightweight aggregate particles, such
as, for
example, polystyrene beads with an aqueous medium; admixing the wet
aggregate particles with dry finely divided cementitious material to form a
coating
thereon; and, thereafter, adding additional aqueous medium in an amount to
produce a coherent formable uncured concrete or plaster.
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U.S. Patent No. 4,011,355 issued March 8, 1977 to Mandish et al.,
discloses a coated, lightweight aggregate, in particular expanded polymer
beads,
such as, expanded polystyrene beads, for mixing with cement, sand and water
for producing a lightweight construction material is provided in which
expanded
polystyrene beads are coated with a mixture formed of dehydrated lime and
hydrated alumina with water in an amount to impart a suitable consistency and
a
wetting agent. A method of making the mixture and coating the beads is also
provided.
U.S. Patent No. 4,398,958 issued August 16, 1983 to Hodson et al.,
discloses a method of making lightweight concrete incorporating expanded
polystyrene beads comprising, first, coating the expanded beads with an
aqueous surfactant solution, which preferably contains a substantive cationic
surfactant, e.g. a substituted or ethoxylated quaternary ammonium compound
containing a Clo to C1$ alkyl substituent or an ethoxylated primary or
secondary
amine having a C10 to C18 alkyl substituent, and a non-ionic surfactant such
as an
ethoxylated primary or secondary alcohol or a nonylphenol-ethylene oxide
condensate. The wet beads are coated with dry cement and then mixed with a
further supply of cement, water and sand or aggregate to complete the concrete
mix.
U.S. Patent No. 4,385,156 issued May 24, 1983 to Ingram et al., discloses
a process for producing styrenic polymer expandable beads that are useful in
forming heat-resistant foamed articles comprising forming an aqueous
suspension of initial styrenic polymer beads and adding thereto a portion of a
comonomer solution of styrenic monomer and methacrylic acid, which solution
also contains a polymerization regulator, forming an emulsion of catalyst,
monomer solution and polyvinyl alcohol suspending agent, adding portions of
the
emulsion to the suspension and then adding the remainder of the comonomer
solution to the suspension, and the suspension with added monomers is heated
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to copolymerize the styrenic monomer and methacrylic acid about the initial
beads and form a coating about the beads.
U.S. Patent No. 4,433,029 issued February 21, 1984 to Senda et al.,
discloses expandable thermoplastic polymer beads and method of producing
same, wherein a core of a polymer of one or more vinyl monomers is
substantially surrounded by a layer of a polyolefin comprising one or more
vinyl
monomers, with a foaming agent contained in at least the core.
U.S. Patent No. 7,128,973 issued October 31, 2006 to Park disclose
expanded polystyrene particles having a polyvinyl acetate resin-based
functional
skin layer, and a process thereof are provided. The particle includes an inner
expanded polystyrene layer; and a functional skin layer.
U.S. Patent No. 7,255,738 issued August 14, 2007 to Semmens describe
a lightweight cementitious composite material includes expanded synthetic
polymer particulate having a particle size of between 0.0625 and 0.5 inches. A
dispersant coating on said particulate suppresses electrostatic attraction
between
particulate particles. A matrix surrounds the particulate and is present from
0.25
to 1 pound per gallon of dispersant coated particulate.
The invention was made in recognition of the need for a more efficient
system and process for producing expanded polystyrene (EPS) beads coated
with a coating composition and a concrete mixture containing the coated EPS
beads.
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SUMMARY OF THE INVENTION
An object of the present invention is, thus, to provide a system and
process for producing expanded polystyrene (EPS) beads coated with a coating
composition, a coating composition used therefore, and a concrete mixture
containing the coated EPS.
In accordance with an aspect of the present invention, there is provided a
process for applying a coating composition (hereinafter referred to, also, as
Vidabode Coating or VBC) to the EPS beads, and temporarily eliminating the
restrictive gas layer, thus enabling the concrete in the mixture to adhere
fully, and
permanently to the EPS beads, the end result being a mixture that can be
poured
or distributed to form exceedingly strong structural lightweight material,
unique in
it's characteristics of strength and stability when compared to previous EPS
concrete products.
In accordance with another aspect of the present invention, there is
provided a system having a reservoir, a coating chamber, the reservoir and the
coating chamber being interconnected through a piping circuit, which delivers
a
pressurized fluid composition from the reservoir to the coating chamber, the
coating chamber having an EPS beads inlet and an outlet duct, the EPS beads
outlet duct being provided with a sieve, an air chamber, the air chamber being
in
communication with the coating chamber, a spraying assembly for delivering a
fluid composition from the piping circuit into the coating chamber, a blower
for
providing forced air into the air chamber and an air diffuser plate, the air
diffuser
plate being positioned between the coating chamber and the air chamber so that
forced air is introduced from the air chamber into the coating chamber through
the air diffuser plate.
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In accordance with still another aspect of the present invention, there is
provided a coating composition (VBC) for coating EPS beads.
In accordance with still another object of the present invention, there is
provided a concrete mixture (hereinafter referred to, also, as VidacreteTM)
containing, among other constituents, the EPS beads coated with the coating
composition (VBC) of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Exemplary embodiments of the present invention will now be described,
by way of example, in conjunction with the following drawing, in which:
Fig. 1 shows a system for coating EPS beads with the coating composition
(VBC) in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The following description is presented to enable a person skilled in the art
or science to which the present invention pertains to make and use the
invention,
and is provided in the context of a particular application and its
requirements.
Various modifications to the disclosed embodiments will be readily apparent to
those skilled in the art or science, and the general principles defined herein
may
be applied to other embodiments and applications without departing from the
scope of the invention. Thus, the present invention is not intended to be
limited to
the embodiments disclosed, but is to be accorded the widest scope consistent
with the principles and features disclosed herein.
Referring to Fig. 1 shown is the system for coating EPS beads with the
coating composition (VBC) in accordance with a preferred embodiment of the
present invention. The coating composition (12), in the form of a solution, is
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drawn from a reservoir (1) by a supply pipe (2) through a filter/strainer (3).
A
check valve (4) is pulled open by pump (5) suction. If the pump (5) is shut
down,
the check valve (4) closes to prevent loss of prime. The pump (5) pressurizes
the
coating fluid for deliver through the piping circuit. Should outlet flow
become
restricted as sensed by a pressure sensor (8), a pressure activated by-pass
(6)
diverts flow back to the reservoir. Pressure can be monitored, for example, by
a
pressure gauge (9). A supply manifold (10) which houses a plurality of nozzles
(11) is provided to deliver the spray coating (12) in a coating chamber (24).
The system further includes a blower (13), which provides forced air (14)
in the air chamber (15) to pass through an air diffuser plate (16). The inlet
from
the expander (17) and inlet duct (18) bring in the uncoated EPS beads. The
coating composition (12) is sprayed on and the coated EPS beads (21) are
forced through a rotating sieve (22) to ensure a maximum size specification is
met prior to exiting at the outlet to a storage silo (23).
The specific purpose of the coating composition of the present invention is
to enable concrete to adhere to EPS beads in a concrete and EPS mixture, and
the purpose of said light-weight concrete mixture being to enable the creation
of
a uniquely strong and sturdy lightweight concrete that is used to manufacture
pre-cast concrete panels used to construct cost-effective homes that are
energy-
efficient, arid withstand wind, fire, flood and earthquake to meet the
variable
structural challenges of a changing world climate.
The structural light-weight concrete formula was designed to allow for the
creation, through a specific and proprietary production process, of pre-cast
structural concrete wall and roof panels that can be transported to
construction
sites and set into position creating a simplified, light-weight cost-effective
concrete structure that will withstand any climate and weather damage.
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Said light-weight concrete mixture can be molded into wall and roof forms
which are then conveyed into a specifically designed curing facility, where it
will
cure sufficiently to be removed from the curing area and transported in less
than
approximately 3.0 hours. The pre-cast wall and roof panels can be transported
to
building sites in sequence, and set into position on a prepared certified
engineered foundation, and fastened together utilizing a two-part adhesive;
said
methods result in a three-dimensional structure that is fire, wind,
water/flood,
earthquake/seismic, mold/mildew, and pest resistant, suitable for all
geographic
regions and climates.
An example of a concrete mixture (VidacreteTM) of the present invention is
provided hereinbelow in Table 1:
Table 1
Material 96psf
Type 10 Cement 460 kg
Silica Fume 0 kg
Sand (SSD) 895 kg
Water 128.5 L
Euco CIA 1.5L
Plastol 5000 4.9 L
Fibers (AFT 50 mm) 4.6 kg
EPS Beads 0.368 m3
As explained above, the EPS beads are coated with the coating
composition (12) of the present invention, which is designed to eliminate a
restrictive gas layer on EPS beads that otherwise prevents concrete from
adhering to EPS beads properly.
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The coating composition (12) adheres to the beads, and has a porosity
allowing the gas to dissipate, thus enabling a strong attraction and permanent
adherence of the concrete to the EPS beads, with said adherence of concrete to
EPS beads creating a mixture that can be pre-cast into panels significantly
stronger and sturdier structurally than existing methods allow for. The
coating
creates strength and sturdiness in an EPS and concrete mixture, where previous
EPS concrete mixtures failed.
In accordance with a preferred embodiment of the invention, the elements
of the coating composition (12) are as follows: Thalcyanine (1 part per 100)
and
Polyvinyl acetate (free radical vinyl polymerization of the monomer vinyl
acetate)
and Polyvinyl alcohol and various additives, known to a person skilled in the
art,
to improve flow and surface wetting. This treatment encourages adhesion of the
cementitious portion of the VidacreteTM mix to the bead resulting in increased
strength of the overall composite.
free radical
~H,,= vinyl polymerization
~~ - +CH~ -CH~
O
i i
C=0 C=O
CH3 ~~~
iinyl acetate poly(vinyl acetate)
In a first step, the beads are specifically made to the correct size and
density for the process, within the manufacturing plant, as known to a person
skilled in art, for the purpose of creating the Expanded Polystyrene (EPS)
material that is used at this stage in the process. For example, pre-expanders
which come equipped with "fluid bed dryers" for the finishing of the EPS beads
once they have been expanded to the proper size from their original resin
state
may be used. Once the EPS beads have been treated through the spray
application of the coating composition, they are transported from the fluid
bed
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dryer to the EPS bead air conveyor to silos with measured portions of the
beads
being moved to the mixer by an air conveyor system and placed in pre-measured
bins. The beads in the EPS bins are emptied into the automated concrete batch
mixers at the correct time, as one skilled in the art would know. Sequencing
of
time and conveyance of EPS and all other materials will be handled by a
computer automation system which is known and normally used by those skilled
in the art pertaining to the present invention.
The advantage of having expanded polystyrene beads in the concrete
mixture of the present invention, is readily apparent to a person skilled in
the art,
and is fourfold:
1) It creates a lighter concrete mixture, more useable in light
construction such as homes and some commercial buildings. The concrete
mixture of the present invention weighs about 95 (-+) pounds per cubic foot as
compared to regular concrete which weighs 150 pounds per cubic foot;
2) The coating treatment causes the concrete to be attracted to the
beads. This adds greatly to the strength of the panels;
3) The concrete mixture of the present invention is fireproof with the
burn characteristics of asbestos cement; this means that it does not
contribute to
or assist combustion in any way nor is there any form of "off-gassing"; and
4) The coating process allows finished panels to have microscopic air
pockets that prevent the advent of cracking or spalling (flaking of surface
layers
of the concrete) in very cold temperatures.
In accordance with the present invention, the EPS bead, as component of
concrete mixture, should be of a consistent size of approximately 3/16 inch in
diameter. The sand, as a component of cementitious mixture, can be washed,
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coarse "broken" granule concrete sand. It is preferable, to have non-reactive
sand consisting of broken granite, however, although preferable, it is to be
understood that the availability of the sand with all of these characteristics
is
limited and any sand or the like known to a person skilled in the art may be
used
in accordance with the invention.
In a preferred embodiment, in winter conditions, the sand may be heated
during the manufacture of the mixture.
One mixing sequence, in accordance with the invention, may require that
the sand, cement and water be placed in the mixer first, and after several
rotations, the additives and fibers are added (specific by weight and volume),
and
the mixer further rotated. Once it is clear to a person skilled in the art
that the
contents are thoroughly mixed, the EPS beads are added and the mixer runs for
a short time (for example, 10-15 seconds) in order to draw the EPS beads
completely into the mix. However, after the step of adding the EPS beads to
the
mixture the mixer may run for any period of time necessary for the beads to
become homogenously distributed into the mixture. However, the entire mixing
process should not exceed approximately 90 seconds.
Any mixer known in the art, which is suitable to the present invention, can
be used. However, preferably, the mixer can be a twin shaft mixer; with mixing
paddles designed to draw the EPS beads down into the mixture, and if said
paddles are not designed to specifications, the EPS beads will float on top of
the
mix without properly becoming a part of the mass mixture, and will wear down
through the abrasive action of the aggregate in the mix.
The fiber additive can be a polypropylene material.
The elements of the coating composition are preferably maintained in a
temperature that is above freezing. The beads are sprayed with the coating
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composition and dried in a fluid bed dryer and transported to holding silos to
await introduction into the cementitious mixture.
As stated above, the coating composition and process for applying the
coating composition to EPS beads enable the concrete in the cementitious
mixture to adhere to EPS beads.
The production of EPS beads requires a Fluid Bed Dryer (FBD) in order to
obtain maximum efficiency in the production of EPS beads. The purpose of the
FBD is to prepare the beads for other uses such as block consolidation or
molding into packing materials, etc.
The FBD consists of an open topped container with a screened cover. The
size varies according to the assigned production of the EPS pre-expander
attached thereto. (The expander is referred to as a pre-expander because in
normal usage, the beads are introduced into molds, etc. where the expansion is
furthered by another injection of steam in a partial vacuum atmosphere). In a
preferred embodiment, the size of the FBD in the Vida Production System is
approximately 5.5 meters long, 1.4 meters wide and 1 meter deep. The bottom of
the FBD consists of a perforated aluminum plate. A high-speed fan provides the
necessary air pressure to provide a constant strong airflow through the
perforations.
The expanded EPS beads are introduced from the pre-expander into the
FBD where the airflow agitates the beads and suspends in the air in a tumbling
motion so as to dry the condensed water from the steam in the pre-expander.
The tumbling beads are moved to the end away from the expander. They
pour over an interior bulkhead into an agitator that propels them through a
specifically sized screen into a high-speed airflow, which carries them into
the
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mesh silos where they dry further before being mixed in Vidacrete according to
a
specific formula.
As the beads are carried out of the FBD, they are coated with the Vida
Bead Coating (VBC) by means of airless spray nozzles mounted at the top of the
FBD approximately 60 degrees upstream of the interior bulkhead. The spray
nozzles are specifically sized to the viscosity of the VBC and to the pressure
required to provide the precise coverage of the passing beads.
The airless pump is a modification of the airless paint systems widely
used. The use of the FBD for such coatings is widely used in the industry.
Most
commonly, the beads are coated with a light oil that is required in some
molding
procedures.
INDUSTRIAL APPLICABILITY
The concrete as obtained by the process described above exhibits "wood"
characteristics when driving nails or inserting screws. There is no need for
pilot
holes or anchoring required to adhere items to panels of concrete obtained as
described above. There is no cracking or spalling of the surface in these
applications. The concrete as obtained above also requires less effort to make
modifications than regular concrete. Additional window and doors can easily be
effected with a simple abrasive saw.
The resulting concrete mixture is a cost-effective structural lightweight
concrete that is fire, wind, water/flood, earthquake/seismic, mold/mildew, and
pest resistant, suitable for all geographic regions and climates, and which is
approximately half the weigh of regular concrete. Said structural lightweight
concrete has a specific and innovative formula of additives, cement powder,
water, EPS beads of a specific size, coated by a specific compound.
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LIST OF REFERENCE NUMERALS:
1 Reservoir
2 Supply pipe
3 Filter/strainer
4 Check valve
Pump
6 Pressure activated bypass
7 Return pipe
8 Pressure sensor
9 Pressure gauge
Supply manifold
11 Spray nozzle
12 Spray coating
13 Blower
14 Forced air
Air chamber
16 Air diffuser plate
17 Inlet from expander
18 Inlet duct
19 Uncoated EPS beads
Outlet duct
21 Coated EPS beads
22 Rotating sieve
23 Outlet to storage silo
24 Coating chamber
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