Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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STONE-LIKE LAMINATE
TECHNICAL FIELD
The present invention generally relates to a stone-like laminate comprising a
support layer made from a pre-cured cementious matrix board and a surface
layer
comprising a resin and particles of an inorganic material.
BACKGROUND ART
Sheets of polished stone, such as marble or granite, have become prestigious
material in the manufacture of countertops' or decorative panels, especially
for their
aesthetic characteristics. However, natural stone sheets are very expensive,
mainly due to
the cost involved in shaping and polishing raw stones. In addition, the raw
material is
usually obtained from remote regions and therefore, the cost associated with
transportation contributes to increase the already elevated cost of stone
panels. Other
drawbacks associated with natural stone panels include stone imperfections
that cause
cracking and general fragility of the sheets and staining and bacteria growth
in porosities.
In the past years, may attempts were made to develop panel products having the
appearance of natural polished stone, while being substantially more .
affordable and
avoiding problems related to heaviness, transportation and installation. These
engineered
stone products are, for most of them, produced following a so-called "Brenton-
Stone"
technology, disclosed in U.S. Pat. No. 4,69,010 to Toncelli. Briefly, this
technology
consists in blending a low percentage of a polyester resin with inorganic
particles, such
as stone particles to obtain a relatively dry mass of mixed material. The
mixed material is
then cured to obtain a slab, which becomes rigid after polymerization of the
resin
material. Such engineered stone products are commercialized under trade names
that
include Cambria~~ CeasarStone~, Silestones~, Technistone~ and Zodiaq .
Several drawback are however associated with these engineered stone panels.
For
example, to prevent bending of large surface panels and breaking of panels
during the
polishing process, the slabs must be thick, being most of the time thicker
than 3/4 inch
(2 cm). Therefore, the resulting panels are heavy, difficult to transport and
to handle,
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require very strong panel supporting structures and cannot be stacked onto one
another.
In fact, typical marketed engineered stone products weigh the same as natural
granite,
which increases the handling and installation costs.
To reduce the thickness or the weight of the engineered stone material while
preserving rigidity and solidity, the prior art discloses lamination of the
engineered stone
material on a base layer of wood, plastic or metal. When unpolymerized
material is
poured and cured onto such a layer, shrinkage of polyester resin during
polymerization
causes a tension over the layer, which responds by forming a convex shape, a
characteristic that is not a desirable for a panel. .
Other approaches rely on multi-step laminating. Briefly, this process consists
in
curing the stone like product, removing it from the mold and gluing it on a
support layer
made from wood, metal or plastic with a special adhesive once it is
polymerized. A
disadvantage of the multiple step laminating procedure is that the decorative
part is very
thin and therefore fragile to polish. In addition, the decorative layer being
glued to the
base layer, small air pocket may be formed between the support and the
decorative layer,
creating zones that will eventually crack under small impact or a heat source.
I~elamination of the surface material is also often observed.
Considering the state of the prior art, it would be highly desirable to be
provided
with a laminate panel having the appearance of natural polished stone, while
being light,
easy to handle and to transport, producible at low cost and resistant to
bending,
delamination and heat.
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DISCLOSURE OF THE INVENTION
One object of the present invention is to provide a stone-like laminate
comprising
a support layer and at least one surface layer disposed over the support
layer. The
support layer comprises a pre-cured heat-absorbing cementious matrix board and
the
surface layer comprises at least eighty percent of particles of an inorganic
material and at
most twenty percent of a resin. The resin is effective to ensure adhesion of
the surface
layer on the support layer and to cause the surface layer to form an integral
structure.
It is also an object of the present invention to provide a stone-like laminate
comprising a support layer and at least one surface layer disposed over the
support layer,
wherein the support layer comprises a perforated, scarified or chemically
treated
pre-cured heat-absorbing cementious matrix board. The surface layer comprises
at least
eighty percent of particles of an inorganic material, at most twenty percent
of a resin and
at least one heat-conducting material in particulate form in an amount
effective to
enhance transfer of heat. from the surface layer to the support layer. The
resin of the
surface layer is effective to ensure adhesion of the surface layer on the
support layer and
to cause the surface layer to form an integral structure.
A further object of the present invention is to provide a method for producing
a
stone-like laminate comprising a support layer and a surface layer disposed
over said
support layer. This method comprises:
- providing a support layer having pores or surface irregularities thereon,
and
which consists of a heat-absorbing cementious matrix board;
- applying a thin layer of a resin on at least one surface of the support
layer under
conditions to cause it to penetrate into the pores or surface irregularities
of the
support layer and to form a thin resin layer;
- applying a mixture layer comprising at least eighty percent of particles of
an
inorganic material and at most twenty percent of additional resin on the thin
resin
layer;
- compacting the mixture layer over the support layer;
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- allowing the resin to polymerize to form the surface layer, and the surface
layer
to become an integral structure comprising the thin resin layer and the
mixture
layer.
For the purpose of the present invention, the term "cementious matrix board"
is
intended to mean any a board, panel or the like made from a cementious
material and
includes but is not limited to cement boards, fiber cement boards, light
concrete boards
cement bonded particle board, calcium silicate board, other cement base panel
product
and the like.
BRIEF DESCRIPTION OF DRAWINGS
Reference will now be made to the accompanying drawings, showing by way of
illustration, a preferred embodiment thereof, and in which:
Fig. 1 is a cross-section view of a stone-like laminate according to one
embodiment of the present invention.
Fig. 2a to 2f are cross-section views of stone-like laminates according to
other
embodiments of the present invention.
MODES OF CARRYING OUT THE INVENTION
The present invention relates to a stone-like laminate comprising a support
layer
on which is applied a decorative layer (Fig. 1). The stone like-laminate of
the present
invention is a panel, a slab or a sheet having predetermined dimensions and
designed to
be used as kitchen countertops, bathroom vanity tops, shower wall cladding,
flooring,
table tops or any other decorative panels The stone like-laminate of the
present invention
can be produced as a slab and further cut according to particular needs. For
example, the
stone-like laminate of the present invention can be produced in the same
dimensions as
other engineered stone like products known in the art, such as 3/a inch (2 cm)
thick,
10 feet (304.8 cm) long, and 53 inches wide (134 cm). The panel of the present
invention
is however preferably 10 mm thick including a 6 mm-thick perforated support
layer and
a 4 mm-thick surface layer. Since the panel of the present invention uses
resin and other
materials more wisely than other panels known in the art, as it will be
described in more
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details hereinafter, the stone-like laminate of the present invention is
significantly lighter
than the other known products while maintaining the same strength properties,
for
predetermined specifications. Since the high cost involved in the production
of
engineered stone products is largely due to the cost of polymer resins, the
present
invention proposes a low cost versus strength ratio panel. The strength
properties of the
stone-like laminate makes it more resistant to bending and pressure and
renders possible
the use of machinery traditionally used for the processing and polishing of
natural or
engineered stone products. This step is generally performed with an industrial
mufti-head
polisher, which requires a pressure as high as over 100 metric tons, polishing
fluids and
heat. The stone-like laminate of the present invention is pressure resistant,
highly wet
resistant and highly heat resistant, without encountering any deformation or
dimensional
variation.
Since the stone-like laminate of the present invention is lighter than other
products derived from natural or engineered stones, it is easier to handle and
to install,
and usual carpentry tools can be used to work with. The stone-like laminate of
the
present invention is also impact resistant, termite and vermin resistant,
highly
rire=resistant, moisture resistant and it provides very good and economical
structural
qualities to the final product. In addition, because the stone-like laminate
of the present
invention requires a smaller amount of petroleum-derived resin or polymeric
material
than other engineered stone-like panels, the production of the present
invention causes
less pollution.
Many properties of the present invention are conferred to the stone-like
laminate
by the support layer That is made of a cementious matrix, a fiber cement, a
light concrete
or the like, in the form of a board, and is preferably a pre-cured board and
even more
preferably a heat absorbent-type pre-cured cementious matrix board. The term
cementious matrix board, as used in the present invention, should therefore be
interpreted broadly rather than restrictively and includes, but is not limited
to boards or
panels made from a cementious material such as cement boards, fiber cement
boards,
light concrete boards, cement bonded panicle boards, calcium silicate boards,
other
cement base panel products, or the like. The cemetious matrix board comprises
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aggregates such as ground silica, amorphous silica, micro silica, diatomaceous
earth, coal
combustion fly and bottom ashes, rice hull ash, blast furnace slag, granulated
slag, steel
slag, mineral oxides, mineral hydroxides, clays, magnesite or dolomite, metal
oxides and
hydroxides, polymeric beads, and mixtures thereof, bound together by a binding
agent
such as Portland cement, high alumina cement, lime, high phosphate cement,
ground
granulated blast furnace slag cement, and mixtures thereof. The cementious
matrix board
may further comprise mica, fiberglass, cellulose fibers, natural fibers,
synthetic fibers,
calcium silicate, wood material and mixtures thereof. The support layer has a
thickness
that preferably ranges from 4 to 40 mm. .
The nature of the support layer provides the stone-like laminate of the
present
invention with a good resistance to pressure, heat and water. For example,
support layer
provides the stone-like panel of the present invention with high heat-
resistance, being
capable of absorbing heat over 400°F while avoiding any delamination.
In addition, the
support layer should agree with the process for the production of the stone-
like laminate
of the present invention, which implies high pressures (up to 100 tons), heat
and
humidity. In addition to those physical properties, the cement board provides
the
stone-like laminate of the present invention with an excellent resistance to
delamination.
Resistance to delamination is mainly due to the nature of the cementious
matrix board.
Indeed, the surface layer is bound to the support layer through the polymer
resin
comprised within the surface layer, as it will be described in more details
hereinafter. It
is however acknowledged in the art that polyester or acrylic resins have poor
adhesion
capabilities, which can result in the delamination of the filler resin when it
is poured and
cured over an inappropriate material 'such as plastic, wood or some metal
substrate. The
stone-like laminate of the present invention uses a cementious matrix board as
support
layer which, contrarily to other materials, has a great porosity and.the
capacity of heat
absorption that significantly contribute to the bonding process with the
polymer part.
Porous type cementious matrix boards used as a backup layer provide a good
receptive
layer for polymer resins since the resins penetrate the pores and provide the
stone-like
laminate with an increased mechanical binding.
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The support layer of the present invention can be made integrally of cement,
fiber cement or can comprise further elements that enhance its physical
properties. For
example, the support layer of the present invention may comprise an integrated
structure
that enhances the strength of the bond created between the cement board or
fiber cement
board, and the decorative layer. Such integrated structure comprises, but is
not limited to,
fibers, metals, wood, inorganic particles, fiber grids and metal grids.
Alternatively, the
support layer can be processed so as to increase adhesion with the decorative
layer. Such
processing of the support layer includes mechanical perforation or
scarification, chemical
treatment of the support layer or combinations thereof. Perforation and
scarification of
the porous fiber cement board will act similarly as a radiator that will take
the heat of the
decorative layer and will transmit he energy to the ambient air. In addition,
perforations,
scarifications or any other surface irregularities increase the mechanical
bound between
the surface layer and the support layer. The cement board may comprise a
sealant or any
other agent that will increase its waterproofing or a metal or aluminium
sheet, grid,
structure or the like to increase heat evacuations from the cement board. To
minimize
post-curing convex bending of the laminate, which is attributable to shrinkage
of the
decorative layer, the cementious matrix board can be curved so as to obtain a
concave
shaped board prior to curing the surface layer. Alternatively, agents such as
thermoplastics can be added to the cured decorative layer to prevent further
shrinkage.
Thermoplastics used for that purpose are commonly referred to as low-profile
additives
(LPAs) and include polymethyl methacrylates, vinyl chloride-vinyl acetate
copolymers,
polyurethanes and styrene-butadiene . copolymers. The cement board may also be
processed to enhance the esthetical properties of the stone like laminate. For
example,
cementious matrix board can be embossed, engraved, painted or a combination
thereof to
give an impression of color and depth.
The surface of decorative layer of the present invention serves mainly for
aesthetic or decorative purposes since it confers the appearance of a polished
stone panel
to the laminate of the present invention, while being non-pourous and
resistant to stain,
heat and scratches. The surface layer of the present invention is preferably
0.7 to 10 mm
thick and more preferably 5 mm-thick to prevent the presence of small air
pockets and
reduces the need of requiring the use of vacuum to obtain resistant stone-like
laminate.
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The surface layer comprises at least eighty percent (80%) of an inorganic
material and at
most twenty percent (20%) of a resin, but preferably comprises at least ninety
percent
(90%) of an inorganic material and ten percent (10%) of a resin and more
preferably
ninety-three percent (93%) of an inorganic material and seven percent (7%) of
a resin.
The particles of inorganic material of the decorative layer include any
inorganic
material in the form of particles. The term particle as used herein is
intended to mean any
particle, granule, pellet, chip, fragment, grain, crumb or the like from any
opaque or
transparent inorganic material suitably usable for the purpose of producing
the stone-like
laminate of the present invention. The inorganic material is however
preferably includes
a mineral, and more preferably stone, rock, sandstone, limestone, boulder,
pebble,
calcite, feldspar, glass, marble, mica, obsidian, sand, silica, wollastonite
alumina
trihydrate, calcium carbonate, silica, alumina trihydrate, antimony oxide,
onyx, talc,
titanium dioxide, calcined talc, magnetite, siderite, ilmenite, goethite,
galena, coal,
pyrite, hematite, limonite, biotite, natural granite, anhydrite, chalk,
sandstone, or the like,
in the form of particles or powder, and more preferably quartz particles. The
inorganic
material of the present invention may be obtained, for example, by crushing
natural
stones or minerals to obtain a determined mesh. The inorganic material of the
present
invention is preferably constituted by particles having a size that ranges
between 0.0001
and 20 mm and more preferably by a combination of 6 mesh (1.7 - 5.6 mm), 10
mesh
(0.6 - 3.35 mm), 24 mesh (0.15 - 1.18 mm) and 325 mesh (less that 44 microns)
inorganic particles. A skilled artisan will understand that in addition to
particles of
inorganic material, various filled or unfilled pigments or dyes, insoluble
chips of
polymeric materials such as cellulose, polyethylene, ethylene copolymers,
cross linked
polyacrylic polymers, polyesters, polypropylenes, cross-linked polyvinyl
chlorides,
cross-linked acrylic polymers, polyethylene, ethylene copolymers, phenolic
resins,
urea/formaldehyde resins, colored chips, hydrated alumina, cross-linked
polyvinyl
chloride and polyesters, polyacetals, pigments, dyes, colored. rocks, colored
glass,
colored sand, wood products or ceramic particles can be added to the
decorative layer to
increase its esthetical aspect. The surface layer may further comprise heat-
conducting
particles adapted for enhancing transfer of heat from the surface layer to the
support
layer, such as, but not limited to, reflective flakes and metal particles.
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The resin that can be used in the context of the present invention includes
any
resin capable to bind inorganic material particles together, but is preferably
a clear,
transparent or translucent resin. Such resin includes, but is not limited to
polymer resins
such as polyesters, acrylics, epoxy, phenols, silicones, urethanes, siloxanes,
silanes, and
combinations thereof. For example, wide variety of generally clear,
transparent or
translucent thermosetting polyester resins are known in the art and fall
within the scope
of the present invention. Such resins include acrylic resins, vinyl ester
resins, epoxy
resins and the like. For the purpose of the present invention, unsaturated
polyester resins
are preferred for reasons of cost, availability, clarity and ease of handling.
Depending on
the nature of raw materials and on how the resin is manufactured, polyester
resins can be
formulated to meet any one of a wide range of special needs. Polyester resins
are
obtained by copolymerization of styrene and unsaturated polyester formed by
reacting an
alpha, beta-unsaturated dicarboxylic acid with glycol. Other unsaturated
polyester resins
may be obtained by the polycondensation of dicarboxylic acid, such as phthalic
acid or
isophthalic acid, with dihydric alcohol such as ethylene glycol or propylene
glycol.
The stone-like laminate of the present invention is obtained by providing a
pre-cured and heat absorbing cement board on which is poured a mixture
comprising the
resin and the inorganic particle material. The mixture is then compacted onto
the cement
board, using a pressure ranging preferably from 100 pounds to 100 metric tons
over the
whole laminate and more preferably a pressure of 3000 pounds per square foot .
The
compaction step may further comprise vacuum treatment and vibration so that
any gas
found within the surface layer will be removed and preferably comprises a
vibration step
of sixty (60) seconds at 3500 vibrations per minute. Further compaction
enables the
stone-like laminate to cure. The use of a catalyst that will increase the
resin
polymerization rate during the curing step is also preferred, and more
particularly the use
of 2% (v/w) catalyst, such as a peroxide catalyst commonly used for the
polymerization
of unsaturated polyester resins. Since the polymerization rate at room
temperature is not
optimal, curing at high temperatures is also preferred, especially with a
surface layer
comprising a polyester resin. Curing temperatures up to 300°F can be
used since the
cementious matrix board is heat-resistant, but a hot curing at 176°F
for 30 minutes is
preferred. Total curing of the stone-like laminate can be performed for a
period ranging
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from one (1) to twenty-four (24) hours, but is preferably performed for a
twenty-four
(24) hour period. After polymerization of the resin content, the stone-like
laminate is
unxnolded, gauged and calibrated. For further calibration, the stone-like
laminate of the
present invention is polished using a standard polisher.
To enhance the binding of the surface layer on the support layer, a thin layer
of
resin is applied on the cement board prior to pouring the mixture comprising
the resin
and the inorganic material. The thin resin layer is then allowed to penetrate
into the pores
or irregularities of the cement board. The mixture is applied over the thin
resin layer
while the resin of both the mixture and the thin resin layer remains
unpolymerized. The
mixture and the thin resin layer contact each other and form an integral
structure with the
inorganic particle material. Since the resin penetrates and polymerizes within
the pores
or irregularities of the cementious matrix board, it increases the mechanical
bound with
the surface layer. A skilled artisan will understand that the stone-like
laminate of the
present invention is not restricted to a structure comprising a surface layer
perfectly
superposing a support layer. For example, the surface layer of the present
invention can
cover a surface that is wider or narrower than the support layer.
Additionally, a skilled
artisan will understand that the surface layer, although generally planar, may
comprise a
lip that covers at least one side face of the support layer, as illustrated in
Fig. 2a to
Fig. 2e, which constitute an embodiment of the present invention.
Alternatively, the
surface layer may cover two faces or the entirety of the support layer (Fig.
2f). The
laminate of the present invention can also comprise tongue and groove
structures on the
lateral sides of the panel so that multiple stone; like laminate panels can be
fitted into one
another.
While the invention has been described in connection with specific embodiments
thereof, it will be understood that it is capable of further modifications and
this
application is intended to cover any variations, uses, or adaptations of the
invention
following, in general, the principles of the invention and including such
departures from
the present disclosure as come within known or customary practice within the
art to
which the invention pertains and as may be applied to the essential features
hereinbefore
set forth, and as follows with the scope of the appended claims.
