Note: Descriptions are shown in the official language in which they were submitted.
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FLOORING PRODUCTS AND METHODS OF MAKING THE SAME
This application claims the benefit under 35 U.S.C. ~119(e) of prior U.S.
Provisional
Patent Application No. 60/592,488 filed July 30, 2004, which is incorporated
in its entirety
by reference herein.
[0001] The present invention relates to wood / polymer composite products,
such as
flooring products and methods to make the same. The present invention
particularly relates
to a plank or tile core that is structurally durable in providing excellent
wear and durability
properties as well as water resistance. The methods to make the product offer
design
versatility with superior sustainability by optionally incorporating high
amounts of post
consumer or post industrial recycled material into the flooring products
without
compromising the performance and aesthetics. Also, proper selections of the
wear surface
material for the product can greatly reduce the life-cycle cost by minimizing
the frequency of
maintenance.
BACKGROUND OF THE INVENTION
[0002] Commercially available floorings, such as laminate flooring (using high
or
medium density fiberboard or particle board as the core layer), have gained
overwhelming
success in the flooring market. The growth rate of the laminate flooring has
remained in the
double digits since the product was introduced in the United States market.
The success of
this product is credited to certain properties such as stain resistance, wear
resistance, fire
resistance, good cleanability, and the ability to use just about any type of
printed design. In
addition, the overall emission of organic compound vapor is low and the
laminate flooring is
considered color stable and environmentally friendly over other competing
flooring products.
[0003] One concern with commercially available laminate flooring is the
moisture
resistance of the finished product and the sensitivity of the raw materials
(high or medium
density fiberboard, paper, and particle board) to moisture during the
manufacturing process.
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In some instances, the moisture can lead to some serious quality control
issues and
application restraints. For instance, and just to name a few, the higher
moisture content in the
product, such as in the particle board or fiberboard, can cause blistering and
adhesion failure
of the melamine surface to the core. Also, higher moisture contents can lead
to dimensional
instability of the finished product, which then results in the cupping or
doming of the product,
which is extremely undesirable, especially when installers are laying down the
flooring. Also,
excessive moisture contents can create edge peaking due to the swelling of the
product and
such edge pealcing can result in edge chip-off or premature wear-out or can
soil more quickly.
The susceptibility to moisture content also leads to some installers not
wishing to place such
laminate flooring in areas which are subject to having water on the surface of
the floor, such
as in the kitchen and bathroom areas.
[0004] The suppliers of such laminate flooring have appreciated the problems
associated
with their products and have attempted to overcome these problems by
developing laminate
flooring having better moisture resistance by using melamine, phenolic, or
isocyanate binders
to partially replace urea resins present in the laminate flooring. While this
improvement has
made the product more moisture resistant, the current commercially available
laminate
floorings are still prone to moisture damage. For instance, laminate floor
thickness can swell
by more than 10% and water absorbency can exceed more than 15% according to
the 24
hours water absorption test. Another attempted solution at the moisture
resistance weaknesses
of current laminate flooring has led some manufactures to apply a water-
repellant material on
the upper edges of the tongue and groove areas which further serve to resist
any moisture
penetration through joints. Still another attempted solution involves applying
silicone caulk to
seal the edges and voids of the laminate perimeter where the laminate flooring
meets the wall.
However, if very stringent installation instructions are not followed, the
laminate flooring
will still be subjected to moisture damage.
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[0005] Another weakness of laminate flooring is its susceptibility to break or
chip at the
corners of edges and the tongue and the groove profile because fibers in the
high density fiber
board are not cohesively bonded together with chemicals. Rather, they are
pressed together
primarily by tremendous pressure and heat.
[0006] Commercially available flooring that is an acrylic impregnated wood
flooring is
available. A typical acrylic impregnated wood flooring is produced by: 1)
impregnating
liquid acrylic monomer or other suitable monomers into raw wood veneer,
wherein the liquid
monomer is forced into the pores of the wood; 2) followed by polymerizing or
hardening the
acrylic monomer by thermal or free radical polymerization such as gamma
radiation or heat;
3) bonding the impregnated veneer with polyurethane adhesive to the wood
veneer base to
form the finished product; and 4) optionally choosing a glass fiber layer in
between the top
surface and the base to produce a more dimensionally stable product. Typical
acrylic
impregnated wood flooring is not an environmental and operational friendly
product. It takes
a long time to impregnate the liquid acrylic monomer into pores of the wood
veneer. It is
often difficult or impossible to penetrate the liquid fully to the desirable
depth or to penetrate
uniformly into the pores of the wood. In addition, operators need to exercise
tremendous
caution for safely handling noxious liquid acrylic monomer and pay attention
to the
environmental consideration and government regulations. Due to such a time
consuming and
a labor intensive process, the product normally is very expensive.
Consequently, only limited
buyers can afford to use it. However, the acrylic impregnated wood layer
offers excellent
moisture resistance properties, has minimal indentation, and good wear, and
durability
properties. It is ideally used in high traffic areas.
[0007] Accordingly, there is a need to develop a new category of flooring
which
overcomes the above weaknesses and disadvantages of current commercially
available
floorings.
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SUMMARY OF THE INVENTION
[0008] A feature of the present invention is to provide a plank which can be
used in a
surface covering system. The plank is based on a wood/plastic composite as the
core, wherein
fiber or flour portions in the core are preferably encapsulated by the polymer
portion, and
which provides improved moisture resistance, and is not susceptible to damage
caused by
moisture.
[0009] Another feature of the present invention is to provide a plank and
surface covering
system which is versatile for many decorative and wear surfaces (e.g., veneers
- oak, maple,
ash, beech, cherry, hickory, and other wood styles, and e.g., laminate
overlay, direct print,
transfer printing, vulcanized paper, and the like) depending upon the needs of
markets.
[0010] A further feature of the present invention is to provide a flooring
system that has
beneficial sustainability and life cycle cost.
[0011] An additional feature of the present invention is to provide a surface
covering
system having flexibility in shape, size, and joint systems depending upon
customer
preference, installation ease and familiarity, and maintenance ease.
[0012] Still another feature of the present invention is to provide a surface
covering
system which has significant improvements in wear, rupture, chipping and
breakage resistant
properties, such as indentation, abrasion, appearance retention and chemical
and stain
resistance and the like.
[0013] Another feature of the present invention is to provide a surface
covering system
which is a higher value (better performance and lower cost) than the
impregnated wood
flooring.
[0014] Another feature of the present invention is to provide a flooring
system that has
great flexibility in choosing the type of woods and polymers and its ratio of
mixture.
[0015] Another feature of the present invention is to provide a flooring
system that can
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alleviate the requirement of a balance layer on the back of the product.
[0016] Also, a feature of the present invention is to provide a surface
covering system
which has the ability to tolerate some imperfections in the sub-floor or
substrate and thus
avoid telegraphing the imperfections on the surface covering itself.
[0017] A further feature of the present invention is to provide a surface
covering system
which has excellent dimensional stability and flammability resistance and the
like.
[0018] Additional features and advantages of the present invention will be set
forth in the
description which follows, and in part will be apparent from the description,
or may be
learned by practice of the present invention. The features and other
advantages of the present
invention will be realized and attained by means of the elements and
combinations
particularly pointed out in the written description and appended claims.
[0019] To achieve these and other advantages and in accordance with the
purposes of the
present invention, as embodied and broadly described herein, the present
invention relates to
a plank, wherein the plank has a core comprising at least one polymeric
material, at least one
type of natural fiber or flour, wherein the core has a top surface and a
bottom surface,
wherein the core is substantially moisture resistant, having a swelling
property (based on
thickness) of from about 0.5% to about 5%, and wherein the core includes a
downward bow
of from about 0.5% to about 3.5% of the length of the plank. Optionally, the
core includes a
lubricant and/or a compatibilizer/coupling agent. Furthermore, optionally,
affixed to the top
surface of the core can be a print layer, wherein the print layer has a top
surface and a bottom
surface. Also, a protective layer can be affixed to the top surface of the
print layer. The plank
can optionally contain an underlay layer located and affixed between the
bottom surface of
the print layer and the top surface of the core. Furthermore, wood veneers
such as oak, maple,
ash, pine, cherry, hickory, and the like can be affixed as a top layer to the
top surface of the
core, wherein the top layer has a top surface and a bottom surface. Also, a
radiation cured
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urethane acrylate coating or other wear resistant layer can be affixed to the
top surface of the
top layer. Furthermore, a direct digital design of any natural product or art
work can be
printed to the top surface of the core, wherein the radiation cured (or e-beam
cured) urethane
acrylate coatings) or other wear resistant layers) can be affixed to the top
surface of the top
layer. The present invention further relates to a method of making a plank and
can involve the
step of extruding at least one polymeric material, at least one type of
natural fiber or flour,
and optionally, a lubricant and/or a compatibilizer/coupling agent into the
shape of a core and
optionally affixing a laminate on the core, wherein the laminate comprises an
overlay layer
affixed to the top surface of a print layer and optionally an underlay layer
affixed to the
bottom surface of the print layer.
[0020] Also, the present invention relates to a method of making a plank by
printing a
design directly on the top surface of the plank using any number of printing
techniques, such
as embossing gravure printing, transfer printing, digital printing, flexo
printing, and the like.
The method includes applying a protective coating on top of the printed
design, such as a
polyurethane type coating with or without wear resistant particles in the
coating.
[0021] A further embodiment of the present invention relates to making a plank
for
flooring by co-extrusion techniques, which involves extruding at least one
polymeric
material, at least one type of natural fiber or flour, and optionally a
lubricant and/or a
compatibilizer/coupling agent into the shape of the core and also extruding a
layer containing
at least one thermoplastic material with one or more pigmented compounds on
top of the
extruded core, wherein the layer simulates a design, such as wood grain.
[0022] The present invention also relates to planks having the above-described
characteristics.
[0023] It is to be understood that both the forgoing general description and
the following
detailed description are exemplary and explanatory only and are intended to
provide a further
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explanation of the present invention, as claimed.
[0024] The accompanying drawings, which are incorporated in and constitute a
part of
this application, illustrate several embodiments of the present invention and
together with the
description serve to explain the principles of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS:
[0025] Figure 1 is a schematic diagram showing a side view of one embodiment
of the
plank of the present invention.
[0026] Figure 2 is a schematic diagram showing a side view of a spline design
which can
be used in the present invention.
[0027] Figure 3 is a schematic diagram of a sectional view showing another
embodiment
of the plank of the present invention.
[0025] Figure 4 is a schematic diagram showing a groove design for a plank of
the
present invention.
[0029] Figure 5 is a partial side view of one type of tongue and groove system
that can be
used in the planks of the present application.
[0030] Figure 6 shows a side view of a plank which is finish sanded, then
wrapped with a
laminate layer or layers and then cut to have a tongue and groove system.
DETAILED DESCRIPTION OF THE PRESENT INVENTION:
[0031] For purposes of the present invention, a floor panel, or plank
includes, but is not
limited to, any shape or size floor panel. In other words, the floor panel can
be rectangular,
triangular, square, hexagonal, and octagonal or have any number of sides.
Also, the floor panel
can have other geometrical designs, such as curves and the like. As long as
the floor panels can
be joined together in some fashion, the present invention can be used. Thus,
for purposes of the
present invention, floor panel includes these various shapes and designs. In
general, the present
invention relates to a plank which contains a core including from about 30 wt%
to about 95
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wt% of at least one polymeric material, by weight of the core, and from about
5 wt% to about
80 wt% of at least one natural fiber or flour, by weight of the core. Other
ranges include
from about 15 wt% to about 75 wt%, or from about 25 wt% to about 65 wt%, or
from about
35 wt% to about 65 wt%, or from about 45 wt% to about 65 wt% of at least one
natural fiber
or flour, by weight of the core. This core has a top surface, a bottom
surface, and generally at
least four sides or edges. The core of the present invention is substantially
moisture resistant,
having a swelling property of from 0.5% to about 5%, by NALFA Thickness Swell
Test
(Section 3.2 LF O1-2003 Standard) (other ranges for moisture resistance as
determined by the
swelling property are from 1.0% to 4%, or from 2.0% to 4%), and wherein the
core includes a
downward bow of from about 0.5% to about 3.5% of the length of the plank.
Other ranges
for the downward bow are from 1.0% to 3%, or 1.5% to 3%, or 2.0% to 3%.
[0032] The planks of the present invention can have a density of from about 58
lbs./ft3 to
about 73 lbs./ft3. Preferably, the planks of the present invention include a
density of from
about 60 lbs./ft3 to about 70 lbs./ft3. The density of the planks of the
present invention is
measured by Method 1: measurement of weight of a given volume of the product.
Weight is
measured using a balance reading to 0.0001 gram. Volume is determined by
measurement of
dimensions using calipers reading to 0.001," or Method 2: calculation using
specific gravity
of HDPE = 0.93 g/cc and PP= 0.91 g/cc with wood density= cellulose = 1.27 g/cc
and
lubricant package at 1.1 g/cc.
[0033] In one example, the plank of the present invention does not include a
backing
layer. The permanent downward bow of from about 0.5% to about 3.5% of the
length of the
plank can counteract for having no backing layer. This bowing can be achieved,
for instance,
by heat-treating the plank (e.g., .heat treating the bottom surface of the
plank) in order to
provide a sufficient bow (camber or dome) to counteract any dimensional change
of a top
layer (if any) on the core from temperature and humidity in the environment.
The heat
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treatment, for example, can be at a temperature of from about 250° F to
1,000° F (e.g., 300°
F to 800° F or 300° F to 500° F) for a time, such as 3
seconds to 1 minute (e.g., 3 seconds to
25 seconds).
[0034] The planks of the present invention can have a glass transition
temperature (Tg) of
greater than about -50° C. Preferably, the glass transition temperature
of the plank is from
either -45 to -15 deg C (High Density Polyethylene) from -30 to +20 deg C
(Polypropylene)
or from 75 to 105 deg C (polyvinyl chloride). The glass transition temperature
can be from -
45 to 105 deg C. The polymeric material of the present invention can be
present in an amount
of from about 30 wt% to about 95 wt% of the weight of the core. The polymeric
material can
have a melt index of from about 0.4 to about 20 grams. Preferably, the
polymeric material has
a melt index of from 0.8 to about 3 grams. The amount of polymeric material
can be from 40
wt% to 90 wt% or from 50 wt% to 80 wt%, based on the weight of the core.
[0035] The polymeric material of the present invention can be one or more
polymers
having a polyolefin group, such as polyethylene. Other exemplary polymers
include, but are
not limited to, polypropylene, polyvinyl chloride, copolymer of PVC, and also
other suitable
thermoplastics.
[0036] In more detail, the polymeric material in the core can be at least one
thermoplastic
material. Generally, any polymeric material, combinations thereof, alloys
thereof, or mixtures
of two or more polymeric materials can be used for the polymeric material of
the core.
Generally, the polymeric materials are thermoplastic materials that include,
but are not
limited to, vinyl containing thermoplastics such as polyvinyl chloride,
polyvinyl acetate,
polyvinyl alcohol, and other vinyl and vinylidene resins and copolymers
thereof;
polyethylenes such as low density polyethylenes and high density polyethylenes
and
copolymers thereof; styrene such as ABS, SAN, and polystyrenes and copolymers
thereof;
polypropylene and copolymers thereof; saturated and unsaturated polyesters;
acrylics;
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polyamides such as nylon containing types; engineering plastics such as
acetyl,
polycarbonate, polyimide, polysulflde, and polyphenylene oxide and sulfide
resins and the
like. One or more conductive polymers can be used to form polymeric material
of the plank,
which has applications in conductive flooring and the like. The thermoplastic
polymers set
forth in Kirk -Othmer (3rd Edition, 1981) at pp. 328 to 848 of Vol. 18 and pp.
385-498 of
Vol. 16, (incorporated in their entirety by reference herein) can also be used
as long as the
resulting plank has sufficient strength for its intended purpose.
[0037] Preferably, the thermoplastic material is a polyolefin including
polyethylene or
polypropylene, and rigid polyvinyl chloride (PVC), semi-rigid or flexible
polyvinyl chloride
may also be used. Preferably, the olefins or the rigid PVC possesses good
impact strength,
ease of processing, high extrusion rate, good surface properties, excellent
dimensional
stability, and indentation resistance. The flexibility of the thermoplastic
material can be
imparted by using at least one liquid or solid plasticizes which is,
preferably, present in an
amount of less than about 20 phr, and, more preferably, less than 1 phr (e.g.,
less than 20% by
weight of the core), especially in the case of PVC. A typical rigid PVC
compound used in the
present invention to form the polymeric material of the core can also include,
but is not
limited to, pigments, impact modifiers, stabilizers, processing aids,
lubricants, fillers, other
conventional additives, and the like.
[0038] The polymeric material to be processed can be in powder, liquid, cubed,
pelletized
form and/or any other extrudable form. Also, the polymeric material can be
virgin, recycled,
or a mixture of both. Furthermore, the polymeric material can be incorporated
with a blowing
agents) or a mechanically injected gas during the extrusion process to make a
cellular foam
structure core.
[0039] The polymeric materials used to form part of the core can be polyolefin
and
polyvinyl chloride. Polyolefm is preferably, High Density Polyethylene or
Polypropylene.
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PETROTHENE LB 0100-00 can be used and is a high density polyethylene reactor
powder.
LBO100-00 provides excellent polymer dispersion, lower extruder amperage, and
increased
extruder output rates versus pellets of equivalent melt index and density in
wood plastic
composites.
Physical Properties for LB 0100-00
Property Value Units ASTM Method
Melt Index 0.50 g/10 D 1238
min
Density 0.952 g/cc D 1505
Tensile Strength @ 3,960 psi D 638
Break
Elongation @ Break >600 % D 638
Flexural Modulus 185,000 psi D 790
Tensile Impact 120 ft-lb/in.D 1822
Low Temperature Brittleness,Fso <-76C D 746
Heat Deflection Temperature6 psi C D 648
@6 75
Vicat Softening Point 123 C D 1525
Hardness, Shore D 66 D 2240
Environmental Stress
Craclc Resistance,
Fso
Bent Strip 35 hrs D 1693
Bottle >500 hrs D 2561
Exxon Mobil PLTD 1765 Homo-polymer can be used and is a medium melt flow rate
polypropylene homo-polymer.
Physical Properties PLTD 1765
Property Value Units ASTM Method
Melt Index 4.0 g/10 D 1238
min
Density 0.9 g/cc D 792
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Tensile Strength @ 4,900 psi D 638
Yield
Elongation @ Yield 10 % D 63
8
Flexural Modulus 220,000psi D 790
Izod Impact 0.8 ft-lb/in.D 256
Low Temperature Brittleness,<-76 C D 746
F5o
Heat Deflection Temperaturepsi C D 648
@66 91
[0040] PVC resin can be used and is a suspension grade or mass polymerization
grade
homopolymer resin having a preferred molecular weight as reflected by an
inherent viscosity
of from about 0.88 to about 1.0 inherent viscosity. In general, a higher
molecular weight
polymer is preferred from the standpoint of processing stability and,
preferably, the molecular
weight distribution and particle size distribution are narrow in order to
provide a good
balance between processability and properties. Also, a high, uniform porosity
of the resin
particles are preferred to optimize compounding and processing aspects,
including the fast
and uniform absorption of any stabilizer that is present as well as other
ingredients during
compounding.
The polyvinyl chloride can have the following properties:
GEON COMPOUND ASTM METHOD 87150
Type Cube
Cell Classification D1784 13344-C
Specific Gravity 0.2 D792 1.45
Hardness-Durometer ShoreD2240 82
D 3
Tensile Properties - D638 6000
Strength PSI
Tensile Properties - D638 390000
Modulus PSI
Flexural Properties - D790 11000
Strength PSI
Flexural Properties - D790 370000
Modulus PSI
Heat Deflection TemperatureD648 160
F
Unannealed 1.82 MPa (264
PSI)
Coefficient of Linear D696 3.4X10-5
Expansion
in./in. F
Notched IZOD Ft.lb./in. D256 3
of notch @
23C (73F)
Impact Properties - DropD4226
Impact 1.0
in.lb/mil 375F melt T.
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'/4" Dart H.250 Method A 1.0
1/4" Dart H.250 Method B 1.0
1/8" Dart H.125 Method A 1.0
1/8" Dart H.1250 Method B
[0041] Generally, this compound can have a melt temperature of from about 360
to about
390° F. Also, a stabilizer can be present in the polymeric formulation
that forms part of the
core. A preferred stabilizer is a butyl tin mercaptide stabilizer. In
addition, an impact modifier
can be also present. Preferred impact modifiers are acrylic-based from Rohm
and Haas, an
EVA-based impact modifier known as ElvaloyTM from DuPont; and others such as
chlorinated polyethylene and acrylonitrile butadiene styrene, and the like.
[0042] With respect to the above various tables and properties, generally, the
core can
have any one or more of these properties or can have any one or more of these
properties that
are within 25% or within 10% of the stated property values provided. In
addition, the
polymeric formulation can contain at least one processing aid, which is,
preferably, an acrylic
based low molecular weight resin such as Acryloid K-125 or K-175 from Rohm and
Haas.
[0043] With respect to the natural fibers or flour, the natural fibers or
flour in the core is
preferably present in an amount of from about 5% to about 75% or to about 80
wt%, by
weight of the core. Preferably, the natural fibers have a reduced particle
size. This can be
achieved, for instance, by pulverizing and classifying the particle sizes.
Generally, this
pulverizing and the like forms a wood flour. The natural fibers or wood flour
can have a
particle size of about 50 mil or less and, more preferably, about 30 mil or
less. In one
embodiment, the particle size is no less than 7 mil or no less than 5 mil. In
one embodiment,
the particle size of the natural fibers that are present are based on a
particle size distribution.
In one embodiment, about 10 wt% to 40 wt% of the particles have a particle
size of from
about 20 mil to 30 mil, about 10 wt% to 30 wt% of the particles have a
particle size of from
about 15 mil to 20 mil, about 10 wt% to 30 wt% of the particles have a
particle size of from
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about 5 mil to 15 mil, and about 0 wt% to 20 wt% of the particles have a
particle size of
about 5 mil or less. With respect to these particle sizes, it would be
difficult to have the size
ranges as absolute values. Thus, there may be particles outside these size
ranges to a small
extent, such as less than 15% by weight of all particles, and more preferably
less than 10% by
weight or less than 5% by weight of the particles present.
[0044] The following particle size distribution can be used as an example:
Mesh Size Retained mil mm
30 35% 23 0.58
40 30% 16.5 0.42
50-60 30% 11.7-9.8 0.30-0.25
80 5% 7 0.18
[0045] As another example, the wood flour/fibers can have a particle size
ranging from
that passing through 20 mesh screen to that retained on 80 mesh screens. This
20/80 size
fraction corresponds to 180 microns to 850 microns particle size. More
preferably, the size
range corresponds to the fraction passing through a 20 mesh screen to that
retained on a 60
mesh screen. This size 20/60 size fraction corresponds to 250 microns to 850
microns.
[0046] Other weight percentages and particle size distributions or any
combination
thereof can also be utilized.
[0047] The natural fibers or flour preferably have a moisture content of about
1 % or
lower (by weight of fiber or flour). The natural fiber or wood flour most
preferably has a
moisture content of less than 0.5 wt%. The natural fibers can be from any wood
source,
cellulose source, other natural sources, or any combination thereof. Examples
include, but are
not limited to, wood (e.g., maple, oak, pine, cedar, hickory, spruce, poplar,
ash, and the like),
bamboo, lcenaf, jute, hemp, flax, sisal, cotton, coconut flour, rice hull, and
the like. As stated,
generally, any natural fiber can be used which is from trees, plants, parts
thereof and the like.
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For purposes of the present invention, natural fiber and flour include the
above in fiber form
or flour form (i.e., particle size). Synthetic fibers may also be used to
enhance mechanical
properties such as flexural and tensile modulus of the product. The higher
aspect ratio (ratio
of length to diameter), the better enhancement of the properties. In addition
to natural fibers
and flour, fillers that are not natural fiber or flour can be added to the
core formulation to
further reduce product cost and to improve impact properties. While any filler
can be used as
long as it is compatible with the polymeric material and natural fiber or
flour, typical fillers
include, but are not limited to, calcium carbonate.
[0048] The natural fiber or flour can be virgin, recycled, or a mixture of
both.
Furthermore, the natural fiber or flour can be incorporated with a foaming
agents) or a
mechanically-injected gas during the extrusion process to make a cellular foam
structure
core.
[0049] In one example, the planks of the present invention can have a
thickness swelling
property of about 3% or less, and, more preferably, from about 0.5 to about 3%
swelling.
This is significantly less than conventional laminates which have a swelling
of from 12 to
14%. The swelling property is measured by immersing the sample in water for 24
hours
according to the test method NALFA Thickness Swell Test Section 3.2 LF O1-
2003,
incorporated by reference herein.
[0050] The plank of the present invention, preferably, has a bow to counteract
any
dimensional change of the top layer, such as a laminate, on the core from
temperature and
humidity in the environment. Preferably, the planks of the present invention,
especially those
without a backing layer, are domed in order to create an arch for purposes of
achieving
desired dimensional stability.
[0051] The amount of dome can be dependent on the type of surface layer
utilized and
the moisture content of the surface layer at the time of wrapping. The amount
of dome of the
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plank should accordingly be adjusted so that the plank has its ability to
maintain flatness in its
service environment. For instance, in one example where a laminate overlay is
utilized as the
surface layer, the plank can include a downward dome of from about 0.25 inch
to about 2.9
inches and preferably, from about 0.30 inches to about 2.5 inches. For a thin
veneer (e.g.,
0.006 inches) laminated on a polyester backing system, the plank can have a
bow of from
about 1 inch to about 2 inches before being placed in the box. The bow
described above is
measured vertically at the center of the plank against a long straight edge
that touches both
ends. Preferably, the plank of the present invention includes a bow of from
about 1% to about
4% of the length of the plank, based on 0% having no bow and 100% being
perpendicular to
the center.
[0052] In another embodiment of the present invention, the planks of the
present
invention have favorable flexibility which is very suitable for laying the
planks together on a
floor since such flexibility will conform to sub-floors more easily especially
imperfections in
the sub-floor. In the present invention, in a preferred embodiment, the planks
of the present
invention have a plank sag of at least 25 inches and more preferably at least
30 inches. A
suitable range for the plank sag is from about 25 inches to about 45 inches.
The plank sag is
determined by a plank sag test which determines how the plank will conform
under gravity.
The test is conducted by using 6 foot long planks of the core without a
finished top layer
(e.g., no laminate layer). The plank core is clamped with C-clamps to a hedge
of a horizontal
platform (e.g., a table). The plank core is clamped so that as much of the 6
foot length can
hang as possible. The amount that the plank sags at the unclamped end from a
horizontal
plane is measured. As indicated, this shows the flexibility of the product.
The planks of the
present invention preferably have this plank flexibility in association with
the other properties
set forth above. The planks of the present invention have this preferred
flexibility either with
a dome as described above or without a dome.
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[0053] At least one lubricant can be present in the formulation. The amount of
lubricant
can be any suitable amount, such as, for example, from about 1 wt% to about 5
wt% or more,
by weight of the formulation. One example of such a lubricant is from Struktol
(Struktol
TPW104). A lubricant such as a polyester lubricant can be used.
[0054] The lubricant can include an internal lubricant and an external
lubricant. Preferred
internal lubricants, which act internally to alter the cohesive forces amongst
the polymer
chains that result in lower melt viscosity without reducing the strength
properties of the resin,
are metallic stearates such as calcium and zinc salts of stearic acid.
External lubricants, which
act externally to prevent resins from sticking to hot metal processing
machinery by reducing
friction between the surfaces, are preferably low-melting paraffin. Other
examples of
lubricants include polyolefin wax, fatty acid amides, fatty acid esters, metal
soaps and salts
of stearic acid and other organic acids, and the like.
[0055] The core can include at least one compatibilizer/coupling agent for
improving
impact strength, heat distortion temperature, tensile and elongation
characteristics and
modulus of elasticity and lastly reducing moisture sensitivity. The amount of
compatibilizer
can be from about 0.5% to about 5% by weight. An example of a
compatibilizer/coupling
agent that can be used in the present invention is malefic anhydride.
[0056] Preferably, the core is rigid in nature and includes the following
range of preferred
properties: impact resistance, static load resistance, indentation resistance,
moisture
insensitivity, pre-profiled configuration, and the like.
[0057] The dimensions of the core can practically be any shape (e.g., square,
rectangle,
curved, and the like) or size as long as such material can be extruded as one
piece or multiple
pieces. For instance, the core can include a thickness of from about 3 mm to
about 50 mm, a
width of from about 2 cm to about 60 cm, and a length of from about 30 cm to
about 215 cm.
Also, the top surface of the core can, optionally, have a textured surface on
the top surface as
17
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part of the core which is extruded through the die. A mechanical embossing row
can be
located behind the cooling calibrator and after the extrusion die to achieve
surface texturing
of the extruded core. Any variety of textures can be created by this method on
the core such
as wood grains and the like.
[0058] Also, as an option, the core can be 100% solid or can have one or more
cavities or
cells which are located between the upper and lower surfaces of the core. The
solid core is
preferred since it enhances the impact strength and the indentation property
of the product.
The extruded core preferably has the thickness from about 3 mm to about 25 mm,
preferably,
about 6 mm to about 10 mm. The width of the plank has the dimension of 50 mm
to 500 mm,
preferably has the width about 75 mm to 305 mm. While the cavities or cells
are optional, the
extruded core can have cavities having dimensions of 3 mm to about 16 mm in
height,
preferably, about 7.6 mm in height by about 6 mm by about 20 mm in width,
preferably,
about 7.6 mm in width, and can be separated by a wall, preferably, a solid
thermoplastic
material, having a thickness of from about 1.0 mm to about 3.02 mm, preferably
from about
1.27 mm to about 1.8 mm. The optimal dimension of cavities is dependent upon
the
requirement of the product withstanding the potential impact force of falling
objects. The
cavities which are preferably present can be in any shape such as rounded,
oval, or
rectangular. These cavities or cells, preferably, exist across the entire
distance of the core as
shown in Fig. 1. Another advantage is that wires, cables, fiber optics, and/or
piping can be
run through the cavities which makes installation of wiring and piping quite
easy without the
necessity of putting holes through walls, or running wires underneath the
floor or in the
ceiling. Further, if necessary, holes can be drilled through the polymeric
material and the
natural fiber that separate one cavity from another in order to have the wire
or piping go in a
perpendicular direction when necessary. Alternatively, for certain polymeric
and natural fiber
core pieces, the cavities can be run in a perpendicular direction from the
remaining pieces in
18
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order to accommodate the direction that wiring or piping may take when being
placed in a
room.
[0059] The cores which form the plank are preferably all made from the same
die design
and thus they are uniform in appearance. Also, the cavities which are
preferably present in
the core align with the cavities in respective core pieces. Dowels, biscuits
or other equivalent
material can be inserted into the cavities at the short end of the plank in
order to join an
adjacent plank to create a tight seal at each seam. This type of coupling
system, though
optional, can further insure a very secure tight fitting floating floor or
other surface covering.
[0060] Though not necessary, the ends of the plank as well as the tongue
and/or groove
can have a bonding agent applied to these locations in order to seal or bond
the planks
together. Sealant compositions such as tetrahydrofuran have the ability to
work as a bonding
agent to join the planks of wood l PVC composition together. In one of the
examples that
follow, the results show that by using tetrahydrofuran or compositions like
tetrahydrofuran,
the joints of the planks which have been attached with the use of this
composition leads to the
formation of a bond between the planks. This increases the overall bond
strength of two
adjoining boards significantly. This bonding agent can be used not only with
the planks
described above. One advantage of using a bonding agent like tetrahydrofuran
is that it is
simple to use, and leaves no residue on the surface after evaporation. Thus,
no adhesive
marks are left on the surface of the planks. In addition, applying such
bonding agents like
tetrahydrofuran is quite easy since it can be applied by brush or spray or
applicator tip using
gravity or other force such as squeezing an applicator bottle, and any excess
is easily
removed unlike the application of some adhesives for tiles and the like. Other
examples of
suitable bonding agents which have the ability to bond the thermoplastic
planks (e.g., PVC)
include, but are not limited to, methylene chloride and lcetones and the like.
Examples of
ketones include, but are not limited to, methyl ethyl ketone, methyl amyl
ketone, dipropyl
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ketone, methyl isobutyl ketone, n-methyl pyrrolidone, dimethyl formamide,
cyclohexanone,
nitrobenzene, and the like.
[0061] Another option is to use waterborne adhesive such as polyvinyl acetate
Type to
bond the faces of the exposed wood fiber after the plank was machined with a
tongue and
groove joint system.
[0062] Another optional aspect of the core is the presence of a groove and/or
a tongue
design on preferably at least two sides or edges of the core wherein the sides
or edges are
opposite to each other. For instance, the core design can have a tongue design
on one edge
and a groove design on the opposite edge, and it is possible to extrude the
core with a tongue
and a groove configuration on two edges and then machine the dimension of the
tongue and
the groove to the tight tolerance of the joint system required for easing
connection. The
typical dimensional tolerance for the extrusion process is around 15 - 20 mils
(0.015- 0.020
inches), ranges which can be considered too broad for the connection system.
The subsequent
machining process can bring the tongue and the groove dimension within the
tolerance of
adequate fit. It is also possible for machining both edges which are opposite
to each other
having a groove design. The tongue or groove can have a variety of dimensions,
but,
preferably, the groove which is present on two opposite edges has an internal
depth
dimension of from about 5 mm to about 12 mm and a height of from about 3 mm to
about 5
mm. The bottom width of the side having the groove is slightly shorter than
the upper width
of the same side to ensure no gap exists between planks after butting
together. With respect to
the edges of the floor panels, which are joined together in some fashion, the
floor panels can
have straight edges or can have a tongue and groove design or there can be
some intermediate
connecting system used to join the floor panels together such as a spline or
other connecting
device. Again, any manner in which floor panels can be joined together is
embodied by the
present application. For purposes of the present invention, the floor panel
can have a tongue
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and groove design or similar connecting design on the side edges of the floor
panel.
Examples of floor panel designs, shapes, and the like that can be used herein
include, but are
not limited to, the floor panels described in U.S. Patent Nos.: 6,101,778;
6,023,907;
5,860,267; 6,006,486; 5,797,237; 5,348,778; 5,706,621; 6,094,882; 6,182,410;
6,205,639;
3,200,553; 1,764,331; 1,808,591; 2,004,193; 2,152,694; 2,852,815; 2,882,560;
3,623,288;
3,437,360; 3,731,445; 4,095,913; 4,471,012; 4,695,502; 4,807,416; 4,953,335;
5,283,102;
5,295,341; 5,437,934; 5,618,602; 5,694,730; 5,736,227; and 4,426,820 and U.S.
Published
Patent Application Nos. 20020031646 and 20010021431 and U.S. Patent
Application No.
09/460,928, and all are incorporated in their entirety by reference herein.
[0063] In one embodiment, a floor panel can have at least two side edges
wherein one side
edge has a tongue design and the opposite side having a groove design, and
wherein the tongue
and groove are designed to have a mechanical locking system. These two edges
are preferably
the longer of the four side edges. The remaining two edges, preferably the
short joints, can also
have a mechanical locking system, such as the tongue and groove design, or the
short joints can
have a standard tongue and groove design, wherein one edge has a standard
tongue design and
the other edge has a standard groove design. The standard design is a design
wherein the tongue
and groove is not a mechanical locking system but is generally a tongue having
a straight tongue
design in the middle of the edge and the groove design has the counterpart
groove to receive this
tongue. Such a design has many advantages wherein a mechanical locking system
can be used to
connect the long sides of the plank, typically by tilting the tongue into the
groove of a previously
laid down plank. Then, the standard tongue and groove design on the short
edges pernlits the
connecting of the short edge of the plank to the previously laid plank without
any tilting motion
or lifting of the previous laid planks. The adhesive can be applied to all
edges or just to the
standard tongue and groove edges.
[0064] Thus, the present invention encompasses any type of joint or connecting
system that
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adjoins edges of floor panels together in some fashion with the use of
straight edges, grooves,
channels, tongues, splines, and other connecting systems. Optionally, the
planks can be joined
together wherein at least a portion of the planks are joined together at least
in part by an
adhesive. An example of such a system is described in U.S. Patent Application
No.
10/205,408, which is incorporated herein in its entirety.
[0065] Also, as an option, any edge of the plank can be straight or bevel.
Preferably the
edges tapered or beveled so that when two cores are brought together for
attachment, a valley
or V-shaped valley is formed. Preferably, the tapered or beveled edges are at
an angle of from
about 5° to about 55°, and, more preferably, at about a
15° - 45° angle. Also, the length of
the beveled or tapered edge can be from about 1.0 mm to about 7.0 mm on each
core piece. A
preferred design is set forth in Fig. 3.
[0066] The planks of the present invention can include a top layer on the
core. For
example, the top layer can include (a) a high pressure laminate construction
that is comprised
of an impregnated underlayer Kraft paper, a printed decorative layer, and an
impregnated
protective overlay compressed together with heat and pressure to become one
single layer;
(b) a wood veneer; or (c) a vulcanized cellulose layer that is made from a
number of plies of
paper treated with zinc chloride, an acid to make the surfaces of the paper
gummy and sticky,
wherein the gummy plies are then pressed together. The plank of the present
invention does
not require a backing layer, but can optionally have a backing layer.
Preferably, the planks
have no backing layer.
[0067] In addition, the decorative elements) such as wood grains and/or knots
texture
can be embossed (e.g., mechanical or chemical embossing), wherein the design
can then be
directly printed on the surface using, for example, a non-contact type digital
printing
technology. Another option is to incorporate the pigments into extrusion
operation to create
wood grain look on the surface of the planks by disturbing the material flow
in the extruder.
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The decorative element can be any design, like natural appearances, stone,
brick, ceramic,
wood, marble, and the like or can be other designs common to or used by the
floor industry.
The design and overall upper layers can be textured, such as embossed in
register with the
design.
[0068] In one example, the top layer is a laminate on top of the core; a print
layer can be
affixed to the top surface of the core, wherein the print layer has a top
surface and a bottom
surface. The print layer, preferably, is an aminoplast resin impregnated .
printed paper.
Preferably, the print layer has a printed design. The printed design can be
any design which is
capable of being printed onto the print layer. The print layer is also known
as a decor print
layer. Generally, the print layer can be prepared by rotogravure printing
techniques or other
printing means such as digital printing. Once a design is printed on the
paper, the paper can
then be impregnated with an aminoplast resin or mixtures thereof. Preferably,
the aminoplast
resin is a blend of urea formaldehyde and melamine formaldehyde.
[0069] The print paper, also known as the Deco paper, preferably, should have
the ability
to have liquids penetrate the paper such as a melamine liquid penetrating in
about 3 to 4
seconds and also maintain a wet strength and even fiber orientation to provide
good
reinforcement in all directions. Preferably, the resin used for the
impregnation is a mixture of
urea formaldehyde and melamine formaldehyde resins. Urea formaldehyde can
contribute to
the cloudiness of the film that is formed and thus is not preferred for dark
colors and the
melamine resin imparts transparency, high hardness, scratch resistance,
chemical resistance,
and good formation, but may have high shrinkage values. Combining urea resins
with
melamine resins in a mixture or using a double impregnation (i.e., applying
one resin after
another sequentially) provides a positive interaction in controlling shrinkage
and reducing
cloudiness. Any type of paper can be used in the present invention.
Preferably, the type of
paper used is 80 g/m2 weight and includes a thickness of 0.16 mm.
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[0070] Located optionally on the top surface of the print layer is an overlay.
The overlay
which can also be known as the wear layer is an overlay paper, which upon
being affixed
onto the print layer, is clear in appearance.
[0071] The overlay paper is, preferably, a high abrasive overlay which,
preferably, has
aluminum oxide embedded in the surface of the paper. In addition, the paper
can be
impregnated with an aminoplast resin just as with the print layer. Various
commercial grades
of high abrasive overlays are preferably used such as those from Mead
Specialty Paper with
the product numbers TMO 361, 461 (70 g/m2 premium overlay from Mead), and 561,
wherein these products have a range of Taber values of 4000 to 6000 cycles
according to
NALFA Standard LF-O1 3.7. Preferably, the type of paper used is about 46 g/m2
and has a
thickness of about 0.13 mm.
[0072] With respect to the print layer and the overlay, any amount of
aminoplast can be
used. Preferably, the amount of aminoplast resin is from about 60 to about 140
g/m2 and,
more preferably, from about 100 to about 120 g/mz.
[0073] A multilayered overlay can be used to provide printed decoration and
protection
for the product. This overlay can have a printed paper as a decorative layer.
On the top
surface of the printed paper can be a layer of urethane acrylate containing
aluminum oxide
for enhanced abrasion resistance. Above this layer can be another layer of
urethane acrylate
without aluminum oxide for improved surface visuals. Below the print layer can
be a primer
to enhance the bond to the base core material. The multilayered overlay can be
produced by
building layers of the primer liquid, and the two acrylic layers as liquid
onto the print layer
and then e-beam curing to produce the solid cured product.
[0074] As an option, an underlay can be located and affixed between the bottom
surface
of the print layer and the top surface of the core. Preferably, the underlay
is present and is
paper impregnated with an aminoplast resin as described above with respect to
the print layer
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and overlay. Preferably, the underlay is Kraft paper impregnated with
aminoplast resins or
phenolics and, more preferably, phenolic formaldehyde resin or melamine
formaldehyde
resin which is present in an amount of from about 60 g/m2 to about 145 g/m2
and, more
preferably, from about 100 g/m2 to about 120 g/m2 paper. Any type of paper can
be used.
Preferably, the type of paper used is about 145 g/m2 and includes a thickness
of about 0.25
mm. The underlay is especially preferred when extra impact strength resistance
is required.
[0075] Other types of layers, which can be used in the present invention, such
as wood
veneer and vulcanized cellulose layers, can include the same components
described above
with respect to the laminate. Wood veneers used as the top layer can be any
type of species
such as oak, maple, cherry, hickory, beech, pine, walnut, mahogany, chestnut,
and teak and
the like. The thickness of the veneer can be in the range of 0.005 inch to
0.250 inch.
Preferably, the thickness of the veneer is in the ranges of 0.080 inches to
0.160 inches. The
veneer on the top can be decorated with a printed design to highlight the
grains or knots or to
mimic certain wood species or to emboss the surface to create vintage
appearance and the
like.
[0076] As a protective layer, a radiation curing or e-beam curing urethane
acrylate
coatings) can be applied on the surface of any previous layer or on the core
upper surface to
provide the required surface properties such as scratch and wear resistance,
scuff resistance,
stain and chemical resistance and the foremost importance is the appearance
retention. The
coatings) can incorporate the abrasive resistance particles in the urethane
for better surface
protection that typically has abrasion level of 300 - 500 cycles per NALFA
test.
[0077] While the core can be made in a number of ways, preferably, the core is
formed
by an extrusion process wherein the polymeric material, natural fiber, along
with any other
optional ingredients are blended together and are then fed into an extruder by
a feeder,
wherein the extruder, preferably, uniformly mixes the polymeric material with
the natural
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fiber and the application of heat and auger action can melt the polymeric
material to the
extent that it is eventually fed through a die, wherein the die can be in the
shape of the core.
Preferably, the fiber or flour is uniformly distributed and encapsulated
throughout the
polymeric material. Preferably, the fiber or flour is substantially
encapsulated or coated
individually by the polymeric material when formed into the core.
[0078] In forming the core of the present invention, the ingredients making up
the
formulation can be mixed prior to introducing the ingredients into an extruder
or can be
mixed by way of the extruder.
[0079] In making the planks of the present invention, the starting polymer,
which is
preferably a thermoplastic, can typically, be in the form of a powder that is
mixed with the
natural fibers inside the extruder without going through the pre-mixing
process.
[0080] As an alternative, the ingredients, including the starting polymer(s),
and the
natural fiber/flour can be intimately mixed together under heat and/or
pressure to first form
pellets of the material. These pellets can then be introduced into an extruder
for formation of
the desired shape of the core. The pellets can have any size suitable for use
in an extruder.
[0081] The natural fibers can be reduced to the desired particle size by any
reducing
technique, such as using a pulverizer, mill, and the like. In addition, to
obtain the desired
moisture content in the natural fibers, any drying technique can be utilized
such as
conductive, convective, and radiation heating means.
[0082] In more detail, the extrusion process permits a) an economically
feasible design
by designing a profile with cavities inside the structure and b) a highly
versatile method of
achieving the complicated profile design of the preferred plank in conjunction
with additional
machining afterwards for the tongue and groove, for instance. Generally, the
extruder can be
designed to uniformly mix the various ingredients together to extrude, using a
die, in the form
of a core. While any extruder can be used which can extrude the desired design
of the plank
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for polymeric and natural fiber materials, preferably, the extruder is a twin
screw extruder,
such as one from American Maplan Corporation, such as model TS-88 or TS-110.
The TS-88
includes the ability to process polymeric profiles with a maximum output
capacity of about
900 lb/hr, based upon a compound bulk density of 37 lb/ft3. The TS-88 is a
twin screw
extruder which includes a barrel heating section and a cooling section as well
as a vacuum
system. In the extruder, there can be 12 temperature zones with 6 for cooling
and a
temperature control system.
[0083] Preferably, the plank can be prepared by extruding the core as
described above
and forming a top layer, such as a wood veneer or laminate or vulcanized
cellulose layer. The
laminate can comprise the overlay affixed to the top surface of the print
layer and, optionally,
the underlay layer which is affixed to the bottom surface of the print layer.
In one example,
wherein the top layer is a laminate, the laminate can be prepared by, for
instance, any process
customarily used to manufacture laminate films such as a continuous double
belt press. In
general, if an underlay is used, the phenolic impregnated kraft backer, the
print layer and the
overlay can be fed into a continuous double belt press that serves as a
laminating calendar.
Preferably, the continuous operation is an isobaric system wherein pressures
can go as high
as 30 bars and the line speed can be up to 20 meters per minute. The pressure
zone length is
about 2 to 3 meters. In this continuous double belt press system, the isobaric
system provides
a steady uniform pressure effect on each point of the treated surface of the
laminate.
Embossing of the laminate can be accomplished by embossed release paper or the
belt of the
double belt press can be embossed to produce surface textures. In a continuous
double belt
press, the simultaneous heating of the laminate with proper dwell time and
pressure forms the
laminate film which then can be rolled up for subsequent application. Once the
laminate is
formed it can be applied onto the core and is preferably affixed by any means,
such as with
an adhesive. Preferably the adhesive is a hot melt adhesive such as hot melt
glue like hot melt
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polyurethane glue.
[0084] The hot melt adhesive, such as the hot melt polyurethane adhesive, is,
preferably,
applied to the back surface of the laminate film at a preferred temperature of
from about 250°
F to about 300° F, more preferably, from about 250° F to about
275° F. These temperatures
may vary slightly depending upon the adhesive. The application of the hot melt
adhesive to
the laminate can be done by a direct roll coater. The laminate with the
adhesive on the back
surface can then be heated to an adequate temperature to soften the laminate
and allow the
laminate to form to the profile of the thermoplastic core and thus be affixed
permanently. The
typical wrapping machine is designed to hold the laminate to the contour of
the thermoplastic
plank as it is being cooled to below about 90° F to about 100°
F. The thickness of the
application of the adhesive can have an effect on the impact resistance of the
finish product.
If the application of the adhesive is too thick, an impact may cause the
laminate to become
brittle and crack. A thin application enables the laminate to flex less during
impact and
minimize the damage. Application of the adhesive is preferably from about 5 to
about 15 g/ft2
and more preferably from about 6 to about 12 g/ft2. A preferred hot melt
adhesive is Ever-
Lock~ 2U145/2U230 modified polyurethane adhesive reactive hot melt from
Reinhold
Chemicals, Inc.
[0085] Wood veneer and vulcanized cellulose can be laminated in a similar
manner.
These products may be provided as coils or as individual strips. In either
case, the hot melt
adhesive which is heated to the temperatures described above can be applied to
the back of
the overlay material to be laminated onto the base plank. The overlay with
adhesive is then
mated to the base plank under heat and the pressure of multiple rollers. The
heat used needs
to be sufficient to re-soften the hot melt and if necessary to soften the
overlay until it bends
and conforms to the surface onto which it is being laminated. In the case of
certain laminate
overlay products to bend the overlay around a bevel edge, the temperature may
need to be
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300-320 degrees F. If no bending is needed, and re-softening the adhesive will
suffice, the
temperature can be lower, preferably to 230-260 degrees F. The cooling process
begins until
at the end of the line the temperature of the product is between about 90-
100° F.
[0086] As described above, the various planks of the present invention can be
connected
together by a tongue and groove system with a mechanical locking profile, or
using full
spread adhesive to glue the planks together or using spline or snap connector.
A separate
spline or snap connector is a separate piece and is especially effective when
a groove is
present on two, opposite sides or edges of the plank. The snap or tongue piece
can be inserted
into one groove and is long enough to extend outside the groove and fit into a
respective
groove of another plank in order to connect the two pieces together. The
tongue piece or snap
connector can be a co-extruded material whose core is made of a rigid
thermoplastic material
such as polyvinyl chloride and whose outer co-extruded top and bottom shell is
made of a
soft thermoplastic material such as plasticized polyvinyl chloride or
polyvinyl chloride/rubber
blends. The hard inner core allows some rigidity for positioning and
installation ease. The
soft outer shell on top and bottom surface allow compressibility for easy fit
into the plank
groove. In addition, due to topographical features such as teeth on the
spline, an improved
grab onto the teeth of the plank groove can be obtained. In another example,
the tongue piece
or snap connector can be a co-extruded material that is made of at least one
polymeric
material and at least one natural fiber.
[0087] In the present invention, while each of the planks can be affixed to
the sub-floor or
substrate, it is preferred that the planks be attached only to each other
through a connector
system such that there is a floating floor system. This promotes fast and easy
laying of the
floor system.
[0088] With the planks of the present invention, the present invention
achieves many
benefits and advantages such as low cost, moisture resistance and mechanical
properties such
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as impact strength, resistance to indentation and gouges, and beneficial
acoustical properties.
Further, the laminate plank system of the present invention can be used in any
environment,
dry, wet, indoor, or outdoor, since it is not susceptible to moisture. In an
embodiment of the
present invention, the planks are less sensitive to the combined effects of
temperature and
humidity than is the standard laminate product. As a result, the need for T-
moldings to act as
expansion and contraction areas of the floor can generally be eliminated.
These T-moldings
are not only unsightly, but can act as tripping hazards. By the elimination of
T-
moldingsJexpansion joints in the walkway, the present invention allows the use
of the floor in
commercial applications. In an embodiment, the present invention expanded only
one fifth as
much as a standard laminate product under identical conditions. These
conditions take the
product from ambient room conditions to conditions of 90% relative humidity
and 90° F.
Standard expansion joints for laminates are typically placed every 30 feet.
Thus, a hallway of
150 feet would be feasible without an expansion joint with the present
invention.
[0089] In the preferred embodiment of the present invention, the installation
method
utilizes the unique design of the product to eliminate the need for glue used
in tongue and
groove connections.
[0090] Furthermore, the installer has options for installing the plank
product. In one
method, a floating floor installation method can be utilized with a floating
floor, applying
glue to a tongue and groove joining system can be used. Such glues as
waterborne polyvinyl
acetate, two part epoxy or urethane systems or one part moisture cure
polyurethane adhesive
can be used. In this method, no adhesive is applied to bond the product to the
subfloor
surface. The benefits of this method have been described earlier.
[0091] In a second method, a full-spread adhesive is applied between the
underside of the
product and the sub-floor surface. This provides the advantages of added
dimensional
stabilization and sound deadening. Both of these properties would be
beneficial in
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commercial applications. Glues that can be used include reactive type systems
such as
moisture cure urethanes or two part epoxies or urethanes.
[0092] In a third method, a click mechanical locking system can also be
possible.
[0093] In a fourth method, the combination of a mechanical lock system with
adhesive
together can be an option as well.
[0094] In addition, the excellent moisture resistance and sound deadening
qualities of this
product can eliminate the need for underpadding, though use of underpadding is
an option.
[0095] A further embodiment of the present invention relates to a plank which
comprises
the same plank described above but, in lieu of a top layer on top of the
plank, a design is
printed directly on the top surface of the plank using any number of printing
techniques such
as gravure printing, transfer printing, digital printing, flexo printing, and
the like. Or, a
printed thermoplastic film (e.g., PVC) or a wood veneer and the like can be
laminated to a
thermoplastic plank. A protective coating can then be placed on top of the
printed design.
Any type of protective coating or wear layer can be used, such as a
polyurethane type coating
with or without wear resistant particles in the coating. Thus, a plank would
have a core,
where the core has a top surface and bottom surface as well as opposing sides
and a printed
design directly on the top surface of the plank and optionally at least one
protective coating
on top of the printed design. The top surface of the plank as described
earlier can have a
textured surface as described above.
[0096] This type of plank can be made by extruding at least one polymeric
material and
at least one natural fiber into the shape of the core and then printing a
design directly on the
top surface of the plank and then, optionally, applying at least one
protective coating on top
of the printed design and curing the protective coating. The protective
coating can be applied
by conventional techniques, such as with a curtain coater, direct roll coater,
vacuum coater,
differential roll coater, air knife coater, or spray apparatus.
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[0097] In another embodiment of the present invention, a plank for surface
coverings,
such as flooring, has a core and an extruded layer on the top surface of the
core, wherein the
extruded layer includes at least one thermoplastic material with one or more
pigmented
compounds. The extruded layer on top of the extruded core can simulate various
designs such
as wood grain and the like.
[0098] The plank in this embodiment can be made by co-extrusion techniques
which
involve extruding the core and extruding either simultaneously or subsequently
a layer
containing at least one thermoplastic material with one or more pigmented
compounds on top
of the extruded core.
[0099] Another embodiment involves a plank having the same design as described
above
with a printed polymeric film, such as a PVC film placed on the top surface of
the extruded
core. The printed polymeric film can be a polymeric film having a printed
design on the film
wherein the film would preferably be from about 10 to about 20 mil thick. One
or more wear
layers or protective coatings can be placed on top of the printed polymeric
film. The
polymeric film can be placed on top of the extruded core by typical lamination
techniques,
such as heating the printed film, then pressing the film to the extruded core
to bond them
together, or using glue to bond them together.
[0100] With reference to the Figures, the Figures show various aspects of
several
embodiments of the present invention. For instance, Fig. 1 represents a
schematic diagram of
a side view of one embodiment of the plank. The particular Figure is with the
prospective
view of looking at the front edge of the plastic wood composite plank wherein
the groove
(76) would run along each edge of the plank. The spline or tongue (64) is
inserted along the
length of each groove (76). Indicia (72) points to the edges of the spline
having the groove
whereas the indicia (68) points to the lower or bottom surface of the spline
and the indicia
(70) points to the top surface or the surface that typically, but optionally,
receives the print
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layer and the like. As illustrated, the feet or strips (62) of post-extruded
material extend along
the bottom surface of the core from the front edge to the back edge. As can be
seen in Figure
l, typically these post extruded lines of material act as a support mechanism
and typically run
parallel in the same parallel direction as the cavities (60). Preferably, and
as shown in the
exemplary embodiments in Figure 1, the side of the plank which has a groove is
typically
tapered or beveled and is shown by indicia (78).
[0101] Fig. 2 is an exemplary representation of one type of spline or tongue
(64) that can
be used in one embodiment of the present invention. As can be seen in Fig. 2,
the preferably
soft material (82), such as plasticized PVC, is located on the top and bottom
surface of the
spline or tongue in order to ensure a tighter fit with the groove of the
plank. The spline can be
made of the same material as the core such as PVC, or the spline can be made
of a different
material. The spline design, preferably, includes a thiclmess of from about 3
mils to 5 mils
thicker than the groove of the plank (for a solid spline design). The spline
will have a
thickness of from about 24 mils to 42 mils thicker than the groove in the
plank for the double
tooth (top and bottom) design. If the spline is too thick, it can open the
groove and cause edge
peaking. If the spline is too thin, it does not effectively engage the groups
with the teeth in the
groove. The edges of the spline or tongue (64) are tapered or beveled (80) in
order to ensure
that the tongue can be inserted into the groove.
[0102] Fig. 3 makes a reference to a spline (64) which includes teeth (90) on
the surfaces
which engage the groove (76) of the plank. Further, as can be seen in Fig. 3,
the top surfaces
of the plank form a V shape valley (88) and the edge of the planlc touches
each other whereas
the bottom portions of each respective plank are cut in order to have a
slightly shorter length
in order to form a gap (86) which ensures that the top ends (88) touch each
other and do not
leave any gaps on the walking surface of the planks. The top layers) (84) can
be a print layer
and the like.
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[0103] Referring to Fig. 4, Fig. 4 is a depiction of a tongue (76) which has
receiving teeth
(92) for a spline or tongue of the design shown in Fig. 3 (90). Fig. 4 further
shows the post
extruded lines on the bottom surface of the extrusion plank (62) as well as
the various angles
and cuts of the cavity (60) as well as the receiving groove (76). Further, the
beveled or
tapered edge (78) is shown in Fig. 4.
[0104] Referring to Fig 5, a flat spline without co-extrusion top and bottom
surface can
be inserted into groove and bonded with waterborne adhesive such as polyvinyl
acetate as the
glue.
[0105] Furthermore, a regular tongue and groove configuration used on most of
the
engineered wood flooring or solid wood flooring, or click joint systems that
are widely used
as a connection system for laminate flooring can also be possible to join the
planks together
with or without a waterborne adhesive.
[0106] Furthermore, it is also possible to weld the joint together by an
ultrasonic welding
machine in a tongue and groove configuration.
[0107] The planks of the present invention can be used in a variety of
applications
including, but not limited to, wall panels, ceiling panels, flooring surfaces,
decks, patios,
furniture surfaces, shelving, and other surface coverings or parts thereof.
[0108] The present invention will be further clarified by the following
examples, which
are intended to be purely exemplary of the present invention.
EXAMPLES:
Example 1
Laminated Overlay (T-11) on Wood Composite Base with a Hot Melt Polyurethane
Adhesive.
[0109] The laminated overlay layer utilized included a top layer that was
0.004 inches
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thick and was composed of a cross-linked melamine-impregnated paper containing
aluminum
oxide. The top layer was designed to be clear and to protect the decorative
print layer below
it. The second layer, which was located under the top layer, was a gravure-
printed paper for
decorative purposes. The third layer (bottom layer), which was located under
the second
layer, was composed of cross-linked phenolic impregnated Kraft paper. The
purpose for the
bottom layer was to provide support and stability for the top two layers
during processing.
[0110] The three layers that made the laminated overlay were consolidated
under heat
and pressure in a continuous consolidation procedure performed on a Grecon
unit.
Section A
[0111] The core of the plank was extruded wood fiber composite having the
following
formulation:
Maple Wood Fibers 55% by wt.
Exxon Mobile Polyethylene LB 0100-00 40% by wt.
Polyester lubricant (Struktol TPW 104) 5% by wt.
[0112] A small amount (less than or equal to 1%) of color concentrate was
included to
tint the base extrusion. The mesh size distribution of the maple wood fibers
was as follows:
Mesh Size Particle Size % by wt. Retained
(inch) on Mesh
30 0.023 30
40 0.016 30
60 0.0098 30
<60 fines 10
[0113] The extrusion was performed using an American Maplan (division of
Battenfeld
International) TS-110 counter-rotating twin screw extruder. The zone
temperatures as well as
the monitored temperature and pressure readings were recorded and are listed
below in Table
I.
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Table I. Extruder Conditions
Measurement DescriptionMeasured Value
Zone Temperatures
Zone 1 399.7 F
Zone 2 384.7 F
Zone 3 350.0 F
Zone 4 350.0 F
Zone 5 299.9 F
Melt Temperature 380.4 F (between Zone 5 and
die)
Melt Pressure 2176.5 psi (between Zone 5 and
die)
Main Motor rpm 944.5
Main Motor % load 54%
Screw Oil Temp 300 F
Screw Oil Core 326.4 F
[0114] The extruder included a five-inch wide rectangular shaped profile with
a thickness
of 0.345 +/- 0.003 inches.
Section B
[0115] The laminate overlay was adhered to the core by a hot melt cross-linked
polyurethane adhesive. In particular, the adhesive was Forbo (Reichhold) 2U-
316. This
adhesive was heated to 250° F and applied to the phenolic back of the
three-layered laminate
which was slightly preheated to 135° F.
[0116] The laminate was then joined to the core. This was then briefly heated
to 250 -
270° F for re-softening the adhesive. Immediately after the softening
heat was applied, a
roller pressed the laminate firmly onto the core. The product was then cooled
with water to
below 90° F.
[0117] In the rectangular construction with a flat top, high heat in excess of
310° F was
not used because the laminate overlay was not shaped to include a beveled
edge, for example.
The application of higher heat to the edge may be useful if the laminate
overlay needs to be
softened and shaped around a bend or bend portion of the profile.
[0118] When heat is applied to the top of the product or the top layer of the
product (top
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heat), a sufficient amount of heat is also, preferably, applied to the bottom
of the product
(back heat) to bring the product into a thermally balanced state. The amount
of back heat
applied, generally, depends on the moisture content of the T-11 three-layered
laminate, the
product stiffness, and the weight of the base plank. The preferred moisture
contents of
overlay as measured by weight loss for 24 hours at 162° F is 3% - 4%.
If the T-11 laminate
overlay contains 3.5 wt% moisture, a plank should be set with a positive dome
of 250 - 300
mils over six feet for being able to remain its flatness in variable
environments.
Example 2
Wood Veneer Overlay on Wood Composite Base
[0119] The core was prepared as described above in Example 1, Section A, using
the TS-
110 extruder from American Maplan Company. However, the decorative element
adhered to
the top of the core was an actual wood veneer. The wood veneer included
polyester back with
a thin (0.006 inches thickness) red oak veneer adhered to the top of the
polyester. The
polyester was used to hold the thin veneer to be processed as a continuous
coil when it was
wrapped onto the extruded wood composite base. The veneer overlay was adhered
to the
wood composite base with a hot melt polyurethane adhesive Forbo (Reichhold) 2U-
316.
[0120] The temperature and other conditions at which the veneer was wrapped
and the
method of laminating the veneer to the wood composite were the same as the
conditions and
method described in Example 1, Section B, with the exception that cooling
water was not in
contact with the face of the wood veneer.
[0121] To protect the red oak veneer from wear and tear, various fillers,
sealers, and a
polyurethane liquid layer, all of which were properly cured, were applied to
the red oak
veneer on the process line.
The steps and materials used in this processing were as follows:
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Process Step Materials Quantity Applied
Stain UV Durable Auburn Tint 0.21 g/36 in2
Denib
Filler -1 Filler 0.50 g/36 in2
Denib
Filler- 2 Filler 0.20 g/36 in2
Denib
2
i
Sealer (standard)-n
1 Standard Sealer 0.45 g/36
Alox Sealer Sealer with Alum Oxide 0.40 g/36 in2
Denib
2
Standard Sealer-2 Standard Sealer 0.45 g/36 in
Topcoat wet on
wet (50 gloss
coating) High
Gloss UV Curable
0.31 g/36 in2
[0122] The stain
used to tint the
red oak veneer
was the auburn
tint stain. All
the process
steps described
above were in
a continuous line.
The line gradually
increased speed
to
eliminate any back-up and congestion problems. All of the application heads in
the process
were roll applicators. After the UV curable stain weight was applied and
cured, the plank
traveled under denibbing rolls, wherein the raised grains in the staining
process were
removed.
[0123] Next, a clear LTV curable filler was applied and cured. The plank was
again
denibbed, followed by a second filler application weight and denibbing.
[0124] A clear UV curable sealer weight and a curing agent were applied to the
plank
using an application head. This was followed by applying a UV curable aluminum
oxide
sealer and curing the sealer. The plank was then denibbed and a standard UV
curable sealer
weight was applied and cured. Finally, two wet applications of the 50 gloss
Valspar LTV
curable coating were applied, weighted, and cured.
Example 3
Vulcanized Cellulose on Wood Composite Base
[0125] The core was prepared as described above in Example 1, Section A, using
the TS-
110 extruder from American Maplan Company. However, the decorative element
adhered to
the top of the plank was a vulcanized cellulose layer with a printed wood
grain design. The
vulcanized cellulose layer was supplied by NVF Company and is known as Yorkite
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Vulcanized Fiber (YVF). The vulcanized cellulose layer was prepared by soaking
cellulose
fibers in CaCl2. The fibers were then compacted and heated to form a cross-
linked cellulosic
layer. The vulcanized cellulose layer used in this example was 0.020 inches
thick.
[0126] The YVF overlay was adhered to the wood composite base with a hot melt
polyurethane adhesive, such as Forbo/Swift 20-316. The temperature and other
conditions at
which the YVF was wrapped and the method of laminating of the YVF to the wood
composite base were the same as the conditions and method described in Example
1, with the
exception that cooling water was not in contact with the face of the wood
veneer. The YVF
was also protected from wear by a coating. To protect the YVF, a UV curable
coating or a
melamine- impregnated overlay was applied to the YVF before YVF was laminated
to the
wood composite base.
Example 4:
[0127] A pelletized blend of HDPE, pine wood fibers, and coupling agents was
added
with a lubricant at the extruder such that the final formulation was:
Wt%
Wood Fiber 70%
HDPE 22
Coupling Agent 2
Lubricant 6
[0128] This was extruded on an American Maplan TS 110 twin screw extruder into
a
rectangular plank 5 inches wide and 0.340 inches thick. Zone temperatures were
set 320F-
330F, die set at 410- 420F, Melt temp = 350- 355F.
[0129] The plank was tested for percent thickness swell when submersed in
water for 24
hours yielding a value of 2.8 +/- 0.5 %. The plank had a static load indent of
0.0005 +/- .0001
inch. The static load indentation test was run by placing 1160, psi pressure
on the product for
24 hours, removing the pressure, allowing rebound for 24 hours and then
measuring indent.
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Example 5:
[0130] A blend of purchased maple wood fibers 30 - 60 mesh size was mixed with
HDPE and agglomerated into pellets on a Pallmann Palltruder~. The weight ratio
of wood
fibers to HI~PE was 1.4:1. These pellets were extruded with lubricant added at
the extruder.
The extruder used was an American Maplan TS 110 twin screw extruder and the
pellets were
extruded into planks of dimensions described in Example 4. The extruder
temperatures were
similar to those in Example 4.
The final extruded formulation was
Wt%
Wood fiber 54%
Exxon Mobil EA 55-003 (HDPE) 42
Lubricant 4
[0131] The plank was tested for water swell and static load indentation as
described in
Example 4. The values measured were: 24 hour water thickness swell was 3.7 +/-
0.5 %.
Static load 1160 psi was 0.0014 +/- 0.0003 inch.
Example 6:
[0132] Wood fibers were produced by size reduction of wood waste from wood
floor
fininshing operation. The fibers were hammermilled and classified so that the
20/50 mesh
screen size was retained. This produced particles having a size of 0.8 mm to
0.3 mm. These
were agglomerated into a pellet using the Palltruder~ in a blend of wood
fibers to HDPE at a
weight ratio of 1.4:1.
[0133] These pellets were extruded with lubricant added at the extruder. The
extruder
used was an American Maplan TS 110 twin screw extruder into planks of
dimensions
described in Example 4. The extruder temperatures were similar to those in
Example 4.
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The final extruded formulation was
Wt%
Wood fiber 54%
Equistar AD 60-007 HDPE 42
Lubricant 4
[0134] The plank was tested for water swell and static load indentation as
described in
Example 4. The values measured were: 24 hour water thickness swell was 3.1 +/-
0.4 %.
Static load 1160 psi was 0.0012 +/- 0.0006 inch.
Example 7:
[0135] A blend of purchased maple wood fibers 30 - 60 mesh size was extruded
directly
with HDPE and lubricant on an American Maplan TS 110 twin screw extruder into
planks of
dimensions described in Example 4. The extruder temperatures were similar to
those in
Example 4.
The final extruded formulation was
Wt%
Wood fiber 54%
Exxon Mobil EA 55-003 (HDPE) 42
Lubricant 4
[0136] The plank was tested for water swell and static load indentation as
described in
Example 4. The values measured were: 24 hour water thickness swell was 4.4 +/-
0.8 %.
Static load 1160 psi was 0.0010 +/- 0.0005 inch.
Example 8:
[0137] Wood composite planks with Elesgo 350 gram overlay and T-11 Overlay
were
prepared by adhering the respective overlays to a wood composite planks
comprised of 55
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wt% maple wood fibers, 40 wt% HDPE resin and 5 wt% lubricant.
~ Bow-refers to vertical movement of plank ends in relation to the plank
center down
the length of the plank.
o A position where the ends are above the center is called "horns up" or
positive
bow.
o A position where the center is above the ends is called horns down or
negative
bow. This may also be referred to as dome.
~ Cup-refers to vertical movement across the plank. Where the sides are above
the
center in the z-direction, the cup is called positive cup. Where the center is
above the
sides is called negative cup.
[0138] The negative bow (dome) was induced by setting an infrared heater at
1000
degrees F set point. Actual thermocouple temperature in the infrared oven was
815 degree F.
The planks were run under the heater with the bottom side of the plank facing
the heater. The
speed of the sample under the oven and distance from the IR heater to the back
of the plank
were varied. The speed was varied between 5 and 9 feet per minute and
distances were
varied between 6 and 9 inches. Raytek temperature measurements were taken as
the sample
exited from the oven. Essentially, back heat temperatures in the 300-
500° F range can
induce a negative bow (dome) of 1 to 1 1/8 inch.
[0139] Applicants specifically incorporate the entire contents of all cited
references in
this disclosure. Further, when an amount, concentration, or other value or
parameter is given
as either a range, preferred range, or a list of upper preferable values and
lower preferable
values, this is to be understood as specifically disclosing all ranges formed
from any pair of
any upper range limit or preferred value and any lower range limit or
preferred value,
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regardless of whether ranges are separately disclosed. Where a range of
numerical values is
recited herein, unless otherwise stated, the range is intended to include the
endpoints thereof,
and all integers and fractions within the range. It is not intended that the
scope of the
invention be limited to the specific values recited when defining a range.
[0140] Other embodiments of the present invention will be apparent to those
skilled in
the art from consideration of the specification and practice of the present
invention disclosed
herein. It is intended that the specification and examples be considered as
exemplary only,
with the true scope and spirit of the present invention being indicated by the
following claims
and equivalents thereof.
43
