Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE OF INVENTION
COATED PARTICLE WITH SHIMMERING APPEARANCE AND ENGINEERED
STONE CONTAINING COATED PARTICLES
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention is directed to a coated particle
which has a shimmering appearance to an observer and to
an engineered stone also having a shimmering appearance
due to incorporation of coated particles.
2. Description of the Related Art
Engineered stone products may be produced by a well
known procedure commercialized by Breton S.p.A. of
Castello di Godego, Italy, so-called "Breton Stone". In
this technology, resin precursors are blended at low
weight percentages with crushed stone aggregate to
provide a relatively dry mass of material, distributed
evenly on a support carrier, vibro-compacted under vacuum
and then cured to yield a rigid product. A process used
to practice this technology is disclosed by Toncelli in
U.S. Patent No. 4,698,010. Breton Stone materials are
disclosed for use as flooring tile. Subsequent
improvements to the technology, such as US Patent No.
6,387,985 to Wilkinson and Burchfield increased the uses
of the material for general surfacing, particularly
making it suitable for use as a countertop. Zodiaq
Quartz Surfacing from DuPont is an example of a
commercially available engineered stone. Whether the
product is floor tile or countertop, the slab produced by
the Breton Stone process requires calibration to render
it planar and uniform in thickness, as well as to reveal
the aesthetic features of the product. This is followed
by polishing to render the surface glossy.
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As described in US Patent No. 6,387,985, materials
may be added for a decorative effect. Decorative
additives are distinguished from stone fillers primarily
by the amount present in the composition. The crushed
natural stone filler acts as an aggregate and is
typically present in the a range from 85% to 95% by
weight. Decorative additives such as gemstones, metal
flake or filings, micas, seashells, pearls, colored or
10. transparent polymeric particles, mirrored particles and
pigments have been added in attempts to increase the
visual appeal and aesthetic qualities of the engineered
stone. However, these quantities typically have not
exceeded about 5% by weight, and preferably, do not
exceed 2% by weight. The decorative additives are
thoroughly mixed with the other components during the
blending, or placed on the surface subsequent to
distribution on the support carrier and prior to vibro-
compaction.
However a limiting factor in the incorporation of a
decorative additive is due to contact with heavy
aggregates during manufacture of the final article. Such
aggregate can act to minimize or destroy the desired
decorative effect of the additive.
There is a need for an additive which imparts a
decorative appearance wherein the additive will remain
intact during blending and compacting with heavy
aggregates. Also there is a need for an additive which
imparts a new visual appearance.
SUMMARY OF THE INVENTION
The present invention is directed to a coated
particle having a shimmering appearance to an observer
comprising;
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(a) a refractive particle;
(b) a coating on the refractive particle of (a);
(c) reflective particles embedded in the transparent
coating of (b);
(d) refractive particles embedded in the transparent
coating of (b) ;
with the proviso that the reflective particles of
(c) or the refractive particles of (d) are
primarily at a surface of the transparent coating.
Also the present invention is directed to an engineered
stone containing coated particles.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
A critical requirement in the present invention is
visual in nature and more specifically the requirement is
directed to a shimmering appearance which is present in a
coated particle. Also the shimmering appearance is
imparted by incorporation of the coated particles into an
engineered stone.
As employed herein the word "shimmering" is used in
its normal meaning, namely to shine with a tremulous or
fitful light. "Tremulous" likewise is used in its normal
meaning namely characterized by trembling or tremours.
Transparent Particles
The first required component of the invention is a
transparent particle which has the ability to refract
light. The degree of transparency of the particle may
vary; illustratively s translucent particle may be
employed while in contrast an opaque particle is not
suitable. Glass and transparent quartz are preferred
materials for such particle.
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The transparent particle which refracts light may
vary in size. A particle having a size in a range from 10
mesh to 3 mesh is preferred, in order to have a large
enough particle to demonstrate the shimmering effect,
while not being too large such that the particle would
not be able to pass through a manufacturing process
without being fractured. A larger particle can be used
with modification to the process parameters. The surface
of the transparent particle can be planar, but curved and
multifaceted surfaces are of more interest aesthetically
in that they demonstrate more shimmering effect as the
angle of observation changes. It is understood that both
larger and smaller particles may be employed. However,
generally at least 50% and more preferably 80% of the
transparent, refractive particles will be present in the
ranges set forth above in a final product of an
engineered stone.
Coating
A coating is applied to the transparent refractive
particle which coating is needed to provide abrasion
resistance. Also the coating serves as a binder to hold
additional particles as will be more fully described
below. A preferred coating comprises a polyester which
typically prior to polymerization contains coupling agent
and catalyst. An example of a suitable polyester coating
is described in USP 3,278,662 and USP 5,321,055. Also an
acrylic coating can be employed such as disclosed in USP
6,387,985. The coating prior to polymerization typically
has a viscosity in a range from 1000 to 50,000
centipoise, preferably in the range from 15,000 to 40,000
centipoise to effectively coat the transparent refractive
particle.
Polymerization, or "curing" of the coating can occur, as
it is known to those skilled in the art, by chemical
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initiation, thermal or UV/Visible light, depending on the
nature of the polymer with which the coating is
formulated.
Additives in Coating
In order to obtain the shimmering effect in the coated
particle it is necessary to introduce appropriate
additives in the coating. As a minimum, a first additive
reflects light, while a second additive refracts light.
An example of an additive which reflects light is a
metal (such as copper and brass) which also includes
alloys. Additional examples include mica, holographic
particles, metallized polyesters and reflective polymers
including pearlescent and fluorescent pigments. Examples
of a second additive which refract light are glass and
transparent quartz.
The two additives which reflect or refract light
will be in particle form and will be embedded within the
coating. However, the refractive particles will be
concentrated near the outer surface of the coating (i.e.
the surface which does not contact the innermost
transparent refractive particle to which the coating is
applied). The concentration and size of the particles is
not critical with the understanding that both
concentration and size affect the desired shimmering
appearance and it is necessary for the particles to be
embedded within the transparent coating. Generally the
reflective particles will be uniformly distributed within
the coating. An example of a size for such particles is
in a range from lmicron to 3 millimeters. Generally the
refractive particles need to be concentrated near the
outer surface of the coating and will be smaller. An
example of a size for such particle is in a range from
325 mesh to 34 mesh. In a preferred mode the refractive
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particle will be concentrated at the surface of the
coating.
A further beneficial effect is present from the
additive which is concentrated at the surface of the
coated particle. Such benefit minimizes or eliminates
agglomeration of coated particles since a number are
formed at the same time.
In the above description it is understood that an
individual particle can cause a color shift which is
considered to be caused by a combination of refraction
and reflection. Such color shift is within the scope of
the present invention.
Engineered Stone
The coated particles described above are
incorporated into an engineered stone to provide the
shimmering appearance in the stone. Such engineered
stone is well known in the art and is specific to a
naturally occurring mineral in combination with a binder
and other additives. Typically the engineered stone
contains 85 to 95 % by weight mineral and the remainder
binder (on a basis of mineral and binder). A preferred
engineered stone contains quartz in the amount stated
with binder such as polyester or acrylic. The binder may
be the same binder as employed for the coating of the
particles. The amount of coated particles to impart a
shimmering effect is not critical but illustratively will
be present in an amount of at least 5 percent by weight
of the final composition.
The engineered stone is typically manufactured in
the form of a slab. An advantage of the coated particle
additive is an ability to withstand the weight and
abrasion present in manufacture of the engineered stone.
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Such advantage includes an ability to be uniformly
distributed in the engineered stone such that the
shimmering appearance is present on different surfaces.
Illustratively if the engineered stone is used as a
kitchen countertop with an upper surface (i.e. the
surface which does not face the floor) and side surfaces
can have similar appearances.
Manufacture
The coated particle is formed by applying the
transparent coating to a reflective particle wherein
prior to solidification of the coating both the
reflective and refractive additives are present. The
coated particle is added in formation of the engineered
stone (which manufacture is well known such as set forth
in the Background of the Invention). The coated particle
is capable of being mixed into an abrasive mixture and
undergoes vibration and compaction without loss of the
coating which is needed for the shimmering effect.
The coated particle may be added at a later stage of
the process to minimize abrasive contact. Typically,
this latter addition would require the coated particle be
hand placed on the surface of the uncured mix and
compacted into the topmost portion of the mix. This is
more labor intensive and less efficient. It will also
result in coated particles present primarily on the
topmost surface and leading to an uneven appearance along
edge portions of the engineered stone.
Typically an engineered stone material is calibrated
to remove surface material for uniformity and polished.
It is understood that conventional additives may be added
to coated particles and/or the engineered stone
composition.
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The following examples are provided to further
illustrate the present invention. All parts and
percentages are by weight unless otherwise indicated.
Example 1
The following materials were used.
1/4 x 8 Mesh Glass (Clear, Brown & Green)
30x50 Mesh Fine Crushed Clear Glass
Valspar Promoted Quartz Casting Resin 5766C00012 with
approximately 25% Styrene
Luperox 26M50--peroxide
Silquest A-174-coupling agent
Siberline Silver Holograhic Flake GP 188SV
100 grams of resin were poured into a plastic
container. 1 gram of both Luperox.26M50 and Silquest A-
174 were added to the resin and stirred until well mixed.
To this mixture, 5 grams of Silberline Silver Holographic
Flake GP 188 SV was added and stirred until completely
mixed.
1/, x 8 mesh glass of various colors (clear, or brown
or green) were put into a 4 oz sample cup. This cup was
filled approximately 1/3 to % full with the glass. A
small amount of the resin mixture was added and stirred
using a plastic stir rod followed by adding additional
resin and stirring until all the glass in the cup was
uniformly coated with the resin mixture(approximately 12
- 14% by weight of the binder resin). The resin coated
glass particles were then transferred to a large strainer
to allow for any excess resin mixture to drip off the
glass. The resin coated glass particles were then
transferred to a pail filled with the 30 x 50 mesh fine
crushed clear glass. Using protective gloves with
neoprene on the outside, the resin coated glass particles
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were stirred in the 30 x 50 mesh fine crushed clear
glass. The process was repeated to obtain a quantity of
resin coated particles having a further coating of 30 x
50 mesh fine crushed clear glass. Any excess of the 30 x
50 mesh fine crushed clear glass was removed by use of a
sieve.
The resin and glass coated particles were evenly
spread on a baking sheet and placed in an oven and the
resin cured at 120 degrees Celsius for 45 minutes. Once
cured, any remaining loose fine clear crushed glass was
separated. The coated particles were placed in a bag and
labeled. The above particles were then used in the
engineered stone slab making process as follows;
Materials
1.466 kg Titanium Dioxide (Ti02) pigment
0.070 kg Peroxide catalyst
6.400 kg Valspar. resin
0.104 kg Silquest A-174 silane coupling agent
04.550 kg Coated particles additive
13.410 kg 10 mesh quartz aggregate
21.556 kg 34 mesh quartz aggregate
7.900 kg 84 mesh quartz aggregate
18.45 kg 325 mesh quartz aggregate
The above materials were placed in a mixer and
blended for 215 seconds. They were conveyed to a lay-
down frame and distributed onto a support carrier. The
support carrier with distributed mix was conveyed into a
vibro-compacter and the materials were compacted. After
vibro-compaction, the materials were conveyed into an
oven and cured to form a slab of engineered stone. The
engineered stone slab was polished with the final article
having a desired decorative effect.
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Example 2
The following materials were used
-
3/8 x 1/4 mesh Clear Glass
Silverbond 325 mesh powder
84 mesh quartz.
Valspar promoted quartz casting resin 5766C00012 with 19%
styrene
Luperox 26M50 Peroxide
Silquest A-174 Coupling Agent
Sparkle Silvex 755-20-C Aluminum pigment
Afflair 600 Black Mica pigment.
126 grams of resin was poured into a plastic container,
2.5 grams of both Luperox 26M50 and Silquest A-174 were
added to the resin and stirred until mixed. To this
mixture 6.5 grams of Sparkle Silvex 755-20-C Aluminum
pigment and 3.1 grams of Afflair 600 Black Mica pigment
was added and stirred until completely mixed.
500 grams of 3/8 x 1/4 mesh clear glass was put into a
stainless steel bowl. A small amount of the resin mixture
was added and stirred using the plastic stir rods. Adding
resin mixture and stirring until all the glass in the cup
was uniformly coated with the resin mixture. The coated
glass particles were then transferred to a pail filled
with Silverbond 325 mesh powder and 84 mesh Quartz. The
coated glass particles were stirred around in the fines
until coated. Repeating the above process until there is
a quantity of coated particles in the fines. Once there
were enough coated particles, the fines were poured
through a sieve to separate the fines from the coated
glass particles. The coated glass particles were evenly
spread on a baking sheet and placed in the oven.
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Alternately, some particle were left in the particle
fines and cured. The coated particles cured at 120
degrees Celsius for 45 minutes. Once cured any remaining
loose fines were separated from the coated particles.
The coated particles were placed in a bag and labeled.
The above particles were then used in the engineered
stone slab making process as follows;
Materials
0.009 kg Bayer Black 318M pigment
0.180 kg Sparkle Silvex 755-20-C pigment
0.058 kg Peroxide catalyst
2.890 kg Valspar redsin
0.043 kg Silquest A-174 Silane coupling agent
5.680 kg Coated particles additive
8.285 kg 10 mesh quartz aggregate
6.917 kg 34 mesh quartz aggregate
2.605 kg 84 mesh quartz aggregate
8.155 kg 325 mesh quartz aggregate
The above materials were placed in a mixer and
blended for 215 seconds. They were conveyed to a lay-
down frame and distributed onto a support carrier. The
support carrier with distributed mix was conveyed into a
vibro-compacter and the materials were compacted. After
vibro-compaction, the materials were conveyed into an
oven and cured to form a slab of engineered stone. The
engineered stone slab was polished with the final article
having a desired decorative effect.
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