Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02518018 2005-09-01
FLOOR UNDERLAYMENT
FIELD OF THE INVENTION
The present invention relates to foam laminates and in particular to foam
laminates for use as a floor underlayment.
BACKGROUND OF THE INVENTION
Many flooring systems in residential and commercial buildings may
comprise a floor supported by wood or steel joists. In some flooring systems
the
floor may comprise a finished floor that is disposed above a subfloor. In
single-
family and multi-family homes and small commercial buildings, the subfloor may
comprise a poured concrete slab or be formed from wooden boards or panels that
are laid over the joists. In some apartment buildings, larger commercial
buildings
and other steel-frame buildings, the subfloor may be a steel deck, precast
concrete
slabs or panels, or poured concrete.
The finished flooring provides a decorative, aesthetically pleasing floor
surface. The finished flooring may be wood, such as wood planks, parquet
flooring and wood-block flooring, or a resilient material, such as linoleum,
asphalt
tile, or vinyl or rubber tile or sheet, or carpeting.
Concrete typically comprises a combination of aggregate and a cement
binder having a high water content. After mixing, the cement hydrates and
eventually hardens into a hard stone-like material. In many cases, the
concrete
retains a high moisture content that may slowly dissipate from within the
concrete
over a period of time. In some cases, concrete may also wick moisture from the
surrounding environment, such as the ground, into the concrete. Moisture from
within the concrete may dissipate upwardly through the concrete and come into
contact with the floor.
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Hardwood flooring and wood in general are hygroscopic materials. Liquid
water and water vapor can enter wood which may cause it to swell and change
its
shape and size, potentially causing bubbling. If and when the water leaves the
wood, the wood can shrink which may result in warp, the development of small
cracks in the surface of the wood, twists, bows, or even develop cups or dips
within each piece of wood flooring. In some cases, cracks in between pieces of
wood may open up as the wood dries.
To help prevent moisture from contacting the finished flooring, it may be
desirable to place a moisture barrier between the flooring and the subfloor.
The
moisture barrier may comprise a thin layer of film adhered to the surface of
the
concrete. In some applications an underlayment layer comprising a layer of
film
and a layer of foam, or a polyethylene film/foam laminate, is provided as an
underlayment between the concrete subfloor and finish flooring formed of wood.
The underlayment levels small irregularities in the top surface of the
concrete,
provides a small degree of resiliency to the floor system, and provides a
vapor
barrier to prevent moisture emanating from the concrete subfloor from
attacking
and deteriorating the finish flooring.
Despite the advantages provided by barrier films and floor underlayments,
many barrier films may permit some transmission of water vapor. In some cases,
water vapor may be trapped between the flooring and underlayment. This may
result in the development of mold, fungus and other growths, leading to odors
and
other health concerns. In addition, because of the tendency of these
underlayments
to trap moisture, they may not be usable with wood subfloors which would
deteriorate on prolonged exposure to moisture.
In some flooring systems, a temperature gradient may exist between the
subfloor and the finished floor. In some cases, this temperature gradient may
result
in temperature variations within the underlayment. Temperature variations
within
the underlayment may adversely affect the underlayment. For example, a
temperature gradient may cause one or more portions of the underlayment
material
to prematurely fail, such as the formations of cracks and/or deterioration or
delamination of the foam and film layers.
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Thus, there exists a need for an improved floor
underlayment which provides the cushioning, and floor
leveling functions of the prior floor underlayments, but
which also permits the controlled escape of moisture from
the subfloor so as to avoid the disadvantages associated
therewith.
BRIEF SUMMARY OF THE INVENTION
According to one aspect of the invention, there is
provided a floor underlayment material comprising: a foam
layer; and a film layer having an inner surface attached to
said foam layer and an outer surface including a plurality
of recesses disposed thereon, the recesses defining one or
more fluid pathways through which a fluid is migratable
along the outer surface of the film layer.
According to another aspect of the invention,
there is provided a floor underlayment material configured
to substantially prevent the accumulation of trapped fluids
between the underlayment material and a floor, the
underlayment material comprising: a foam layer comprising
low density polyethylene and having a density that is from
about 1.0 to 2.2 pcf and a thickness of about 0.20 to
1.5 inches; and a low density polyethylene film layer
attached to the foam layer, the film layer including an
inner surface attached to the foam layer and an outer
surface including a plurality of recesses disposed thereon,
the recesses defining one or more fluid pathways, wherein
the one or more fluid pathways define channels through which
a fluid may escape from between a floor and the underlayment
material, whereby the accumulation of trapped fluids is
substantially prevented.
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According to another aspect of the invention,
there is provided a flooring system comprising: a subfloor;
a floor; and a floor underlayment material between the
subfloor and the floor, the underlayment material comprising
a foam layer and a film layer, the film layer having an
inner surface attached to the foam layer and an outer
surface having a plurality of recesses disposed thereon, the
recesses defining one or more fluid pathways through which a
fluid is migratable along the outer surface of the film
layer.
According to another aspect of the invention,
there is provided a method of installing a finished floor
over a subfloor comprising: providing an underlayment
material comprising a foam layer and a film layer attached
to the foam layer, the film layer including an inner surface
attached to the foam layer and an outer surface having one
or more fluid pathways disposed thereon; laying down the
underlayment material onto a surface of the subfloor; and
installing a finished floor over the underlayment material,
such that the fluid pathways extend adjacent to at least one
of the subfloor and the underside of the finished floor.
Embodiments of the invention provide a floor
underlayment material that overcomes many of the problems
discussed above. In one embodiment, the invention is
directed to a floor underlayment material comprising a film
sheet having an inner surface attached to a foam sheet and
an outer surface including a plurality of recesses formed
therein. The plurality of recesses define one or more fluid
pathways through which a fluid may migrate across the outer
surface of the film layer.
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In one embodiment, the underlayment material may
be used in a flooring system to help prevent or limit the
accumulation of a fluid between the floor and the subfloor.
In one alternative embodiment, the underlayment material may
be disposed between a subfloor and floor with the outer
surface of the film layer being disposed adjacent to the
underside of the floor. The one or more fluid pathways
provide channels through which a fluid such as moisture
vapor may escape from within a flooring system and thereby
reduce the accumulation of moisture in the flooring system.
Migration of moisture vapor through the underlayment
material may result in the moisture vapor exiting the film
layer and entering one or more of the plurality of recesses.
The moisture vapor may then migrate through a series of
adjacent recesses until it reaches an opening in the
flooring system through which it may escape into the
surrounding atmosphere. In other embodiments, the
underlayment material may be disposed between a subfloor and
floor with the outer surface of the film layer being
disposed adjacent to the subfloor.
In one embodiment, a fluid migrating across the
outer surface of the film layer may select from multiple
different fluid pathways. In some embodiments, each recess
may be interconnected to two or more adjacent recesses. As
a result, fluids migrating through a recess may be able to
discriminate amongst adjacent recesses in selecting into
which recess it may migrate next. The fluid pathway through
which the fluids may migrate may be based, at least in part,
on which
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pathway has a higher vapor transmission rate. The plurality of recesses may
permit the fluids to select a fluid pathway having the least amount of
resistance
than alternative fluid pathways. As a result, a fluid may migrate through the
recesses in a fluid pathway that may provide the most efficient route of
escape
from within the flooring system.
In one alternative embodiment, the invention is directed to a flooring
system wherein the underlayment material is disposed between a wood floor and
a
concrete subfloor. As discussed above, the plurality of fluid pathways
provides a
means whereby moisture vapor may escape the flooring system and thereby
prevent the accumulation of trapped fluids.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
Having thus described the invention in general terms, reference will now be
made to the accompanying drawings, which are not necessarily drawn to scale,
and
wherein:
FIG. I a is a cross-sectional side view of an underlayment material having a
plurality of recesses through which a fluid may migrate across an outer
surface of
the underlayment material;
FIG. lb is a cross-sectional side view of an underlayment material having
plurality of wave-like recesses that extend across a surface of the
underlayment
material;
FIG. 2 is a cross-sectional side view of a flooring system including the
underlayment material of FIG. 1 a;
FIG. 3 is a perspective view of the flooring system of FIG. 1 a with a
portion of the floor and the underlayment removed for clarity;
FIG. 4 is a cross-sectional side view of the flooring system of FIG. 2
depicting the migration of a fluid through the underlayment material; and
FIG. 5 is a perspective view of the flooring system of FIG. lb with a
portion of the floor and the underlayment removed for clarity.
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DETAILED DESCRIPTION OF THE INVENTION
The present inventions now will be described more fully hereinafter with
reference to the accompanying drawings, in which some, but not all embodiments
of the inventions are shown. Indeed, these inventions may be embodied in many
different forms and should not be construed as limited to the embodiments set
forth
herein; rather, these embodiments are provided so that this disclosure will
satisfy
applicable legal requirements. Like numbers refer to like elements throughout.
With reference to FIGS. la and lb, a floor underlayment material having
one or more fluid pathways is illustrated and broadly designated by reference
number 10. The one or more fluid pathways provide channels through which
moisture may escape from within a flooring system and thereby reduce the
accumulation of moisture in the flooring system. In one embodiment, the
underlayment material 10 comprises a film layer 12 having an inner surface 16
that
is attached to a foam layer 14. The outer surface 18 of the film layer
includes one
or more fluid pathways through which a fluid is migratable across the outer
surface
of the film layer. In one alternative embodiment, the outer surface includes a
plurality of recesses 20 that define the one or more fluid pathways. As
discussed
in greater detail below, the fluid pathways help prevent moisture vapor from
becoming trapped within a flooring system. In the context of the invention,
the
term "fluid" includes liquids and gases, including air and moisture vapor.
Fluids,
embracing both liquids and gases, can typically flow easily across the outer
surface
of the film.
In FIG. 1 a the outer surface 18 of the film layer includes a plurality of
recesses 20 having a diamond-like shape. In some embodiments, each recess may
include one or more connecting channels 22 that may interconnect one or more
adjacent recesses. In one embodiment, the outer surface of the film layer may
include a plurality of raised surfaces 23 in which the plurality of recesses
20 are
formed. FIG. lb illustrates an embodiment of the underlayment material wherein
the plurality recesses have a "wave-like" shape that may extend longitudinally
across the outer surface of the film layer. In some embodiments, outer surface
of
the film layer may include a plurality of the wave-like recesses 20 that are
substantially parallel to each other. In one embodiment, the plurality of the
wave-
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like recesses 20 may be defined by raised surfaces 23. In one alternative
embodiment, the one or more of the wave-like recesses may be interconnected to
one or more adjacent recesses via connecting channels 22 that extend laterally
across the raised surfaces 23. As discussed in greater detail below, the
plurality of
recesses and connecting channels provide one or more fluid pathways through
which a fluid may travel across the surface of the film layer.
In one embodiment, the wave-like recesses may have a width ranging from
about 10 to about 250 mils, 20 to 200 mils, 50 to 150 mils, and from 75 to 125
mils. In some embodiments, the wave-like recesses may have a width ranging
from about 100 to about 125 mils.
During extended use, many prior art underlayment materials have a
tendency to compress as a result of exposure to foot traffic or heavy items.
In
some embodiments, the shape and surface area of the raised surfaces 23 may be
configured so that this so-called "creep" of the underlayment material may be
minimized.
In one embodiment, the one or more fluid passageways may also promote
air flow across the surface of the film layer. Heat energy transfers between a
solid
and a fluid when there is a temperature difference between the fluid and the
solid.
This is generally known as "convection heat transfer". Convection heat
transfer
within the underlayment material may help lessen the amount of thermal
variation
that may be present in the underlayment material. In addition, convection heat
transfer between the underlayment material and a fluid, such as air, in the
one or
more fluid passageways may also help induce fluid motion across the surface of
the film layer. This is generally known as "natural convection" and it is
generally a
function of the temperature difference between the underlayment material and a
fluid that may be present in the one or more fluid pathways. Convection forces
within the underlayment material may permit and drive air flow through the one
or
more fluid passageways. Such air flow may provide several advantages, for
example, the air flow may help the underlayment material to have a more
uniform
thermal distribution so the amount of thermal variation within the flooring
system,
and the underlayment material itself, may be reduced. In one embodiment, the
thermal variation within a cross-sectional slice of the underlayrnent material
may
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be less than 15 F, less than 10 F, and less than 5 F. Additionally, the air
flow
may also help a fluid, such as moisture vapor, to migrate across the surface
of the
film layer so that the fluid may efficiently escape from within the flooring
system.
FIG. 2 is a cross-sectional side view of an exemplary flooring system 40 in
which the underlayment material 10 is disposed between a subfloor 42 and a
finished floor 44. The finished floor 44 as illustrated in FIGS. 2-5 comprises
a
series of wood or wood laminate planks fitted together at their edges. In the
illustrated embodiment, the outer surface 18 including the plurality of
recesses 20
are disposed adjacent to the underside 46 of the floor 44. In some
embodiments,
the foam layer 14 may be disposed adjacent to the subfloor 42. In other
embodiments, the outer surface of the film layer may be disposed adjacent to
the
subfloor (see briefly FIG. 5).
As can best be seen in FIGS. 3 and 4, outer surface 18 includes a plurality
of recesses 20 that are each capable of being in fluid communication with one
or
more adjacent recesses. The plurality of recesses define one or more fluid
pathways through which a fluid may migrate across the outer surface of the
film
layer. The wavy arrows in FIGS. 3 and 4 illustrate a fluid, such as water
vapor,
migrating through the flooring system. FIG. 3 is a cross-sectional perspective
view
of a flooring system wherein portions of the flooring and the underlayment
material have been removed for clarity. Moisture vapor, represented by the
wavy
arrows, is depicted as migrating upwardly from the subfloor and into the
underlayment materia110. Continued migration of the moisture vapor results in
the moisture vapor passing through foam and film layers, 14, 12. Moisture
vapor
may then be disposed between the underlayment material 10 and the underside 46
of the floor 44. Moisture vapor exiting the film layer 12 may migrate into one
or
more of the plurality of recesses. The moisture vapor may then migrate through
a
series of adjacent recesses until it reaches an opening in the flooring system
through which it may escape into the surrounding atmosphere. The series of
adjacent recesses define a fluid pathway through which moisture vapor may
efficiently migrate through the flooring system. In one embodiment, the one or
more fluid pathways comprise a network of interconnected recesses through
which
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a fluid is migratable. As a result, the accumulation of trapped fluids within
the
flooring system may be reduced or prevented.
Moisture vapor migrating across the outer surface of the film layer may
select from multiple different fluid pathways. In this regard, FIG. 3 depicts
moisture vapor migrating through a series of successive and interconnected
recesses as it migrates across the outer surface. In some embodiments, each
recess
may be interconnected to two or more adjacent recesses. As a result, moisture
vapor migrating through a recess may be able to discriminate amongst adjacent
recesses in selecting which recess it may next migrate into. The fluid pathway
through which the water vapor migrates may be based, at least in part, on
which
pathway has a higher vapor transmission rate. The presence of the recessed
structures provide clear channels for the moisture to move around due to the
pressure gradient and natural convection effects. The plurality of recesses
may
permit the moisture vapor to select a fluid pathway providing the shortest
path of
escape or having the least amount of resistance (e.g., the highest moisture
vapor
transmission rate) than alternative fluid pathways. The one more fluid
pathways
defined by each successive recess comprise a dynamic system that can change
with
surrounding conditions such as humidity and temperature, for example. As a
result, a fluid migrating across the outer surface of the film layer may not
limited
to migrating in any one direction or along any single predefined path and may
migrate through the recesses in a pathway that may provide the most efficient
route
of escape from within the flooring system. Additionally, as discussed above,
convection flow may also help a fluid migrate across the outer surface of the
film
layer.
As shown in FIG. 3, many conventional flooring systems provide some
space 50 between the floor 44 and the wall 52. This space may permit some
expansion and contraction of the floor 44 as the temperature and humidity of
the
surrounding environment changes. In some embodiments, the moisture vapor may
migrate through the fluid pathways and into this space. From this space the
moisture vapor may escape the flooring system into the surrounding atmosphere.
In some embodiments, the floor may comprise laminate or wood planks that may
be joined together lengthwise. In some floors, the planks may be joined
together
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via tongue-in-groove joints. Over time as the floor is exposed to various
changes
in humidity and temperature, the space between adjacent planks may open and
close as the planks expand and contract. Spaces between the planks may provide
additional openings through which moisture vapor may escape the flooring
system.
In this regard, FIG. 4 illustrates a flooring system 40 in which the floor 44
comprises a plurality of wood planks 54 that are joined together via a tongue-
in-
groove joint 58. Moisture vapor is depicted as migrating through the
underlayment
material 10 and into the plurality of recesses 20. Depending upon the moisture
vapor transmission rate of the fluid pathways, a first portion of the moisture
vapor
may escape the flooring system by migrating into the space 50 between the wall
and the floor, and a second portion of moisture vapor may escape the flooring
system by migrating through one or more openings 60 that may exist between the
wood planks 54. Thus, the ability of the moisture vapor to migrate through a
plurality of different recesses permits a fluid to select the most efficient
route for
exiting the flooring system.
In another embodiment, a portion or substantially all of the plurality of
recesses may be interconnected with each other to form a network of one or
more
continuous fluid pathways. In this regard, FIG. 3 illustrates a plurality of
recesses
having a diamond-like shape and that are each connected to one or more
adjacent
diamond shaped recesses. Moisture vapor migrating into a recess may then
select
one or more of the adjacent recesses in which to migrate based on which one of
the
recesses provide a pathway of less resistance. In one alternative embodiment,
the
plurality of recesses may comprise a first plurality of substantially parallel
channels that extend laterally across the outer surface and that intersect a
second
plurality of substantially parallel channels. The intersecting channels
thereby form
an outer surface having multiple possible fluid pathways. In other
embodiments,
the outer surface of the film layer may include a plurality of recesses that
may not
be directly connected to one another. It should also be recognized, that the
shape,
size, and depth of the plurality of the recess may be varied so that the outer
surface
provides one or more fluid pathways having a desired rate of moisture
transmission.
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In an alternative embodiment, the outer surface of the film layer may be
disposed adjacent to the surface of the subfloor. In this regard, FIG. 5
illustrates a
flooring system 40 wherein the outer surface 18 of the underlayment material
is
disposed adjacent to the subfloor 42. As discussed above, the plurality of
recesses
define one or more fluid pathways through which a fluid may migrate across the
outer surface 18 of the film layer 12. As shown, in FIG. 5, the recesses may
provide one or more fluid pathways through which a fluid, such as moisture
vapor,
may travel across the surface of the film layer. Here, a fluid, represented by
the
wavy arrows, is depicted as migrating through the fluid pathways. Connecting
channels 23 may interconnect adjacent recesses 20 so that the fluid may move
across the outer surface of the film layer in a direction that may provide the
most
efficient method of escaping the flooring system.
In the embodiment illustrated in FIG. 5, it may be desirable for the film
layer to comprise a material having high moisture vapor barrier properties so
that
moisture vapor may be substantially prevented from migrating through the film
layer and into the foam layer. In some embodiments, the film layer may have a
water vapor transmission rate that is less than about 0.2 grams/day/100 in2 at
1000
F, 90% relative humidity as measured according to ASTM F1249-01. In other
embodiments, the film layer may have a water vapor transmission rate that is
no
greater than about 0.25, 0.35, 0.50, or 0.75 grams/day/100 in2 at 100 F, 90%
relative humidity. In the illustrated embodiment, the plurality of recesses
are
depicted as having a wave-like shape. It should be recognized, however, that
the
pattern and shape of the plurality of recesses may be varied and is not
dependent
on any one particular shape or size.
In some embodiments, the underlayment material may comprise a second
film layer (not illustrated) attached to an outer surface of the foam layer to
produce
a laminate wherein the foam layer is disposed between two film layers. The
second film layer may have moisture vapor barrier properties. In some
embodiments, the second film layer may also include an outer surface having a
plurality of recesses that define one or more fluid pathways. In this
embodiment,
the underlayment material would provide two outer surfaces for channeling
moisture vapor out of the flooring system.
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In one embodiment, the underlayment material comprises a laminate in
which the foam layer and the film are attached to one another. The film and
foam
layers may be attached together in a variety of known ways. Suitable methods
of
attaching the film and foam layers together include, but are not limited to,
the
application of an adhesive including a molten polymer, ultrasonic bonding,
heat
bonding, and the like. In one alternative embodiment, the underlayment
material
may be produced by extruding a layer of polymeric resin directly onto the foam
layer to thereby form a film layer that is thermally adhered to the foam
layer. In
other embodiments, the underlayment material may be produced via heat
lamination by feeding a sheet of foam and a sheet of film through a pair of
heated
rolls that softens and fuses the film layer to a surface of the foam layer.
In one embodiment, the recesses may comprise a plurality of imprinted
depressions that are formed on the outer surface of the film layer. The
recesses
may be formed on the outer surface in a variety of ways including extrusion
molding techniques. In one alternative embodiment, the recesses comprise
imprinted depressions that may be formed by passing the film layer through an
embossing roll or other type of roll having a plurality raised or depressed
surfaces
disposed on the outer circumference of the roll. In some embodiments, the
recesses may be formed by passing a sheet of the underlayment material through
an embossing roll. The height, size, and spacing of the raised surface may be
varied so that the outer surface has a desired rate of moisture vapor
transmission.
In some embodiments, the outer surface of the film layer may be
substantially covered with a plurality of recesses. The depth of the recesses
may
be selected so that the a fluid is capable of flowing across the outer surface
of the
underlayment material at a desired rate. In one embodiment, the moisture vapor
transmission rate across the outer surface of the film is greater than 0.23
grams/day/100 in2. The depth of the recesses may range from about I to 45
mils.
In one alternative embodiment, the average depth of the recesses is between
about
2 to 20 mil or 3 to 19 mil. In other embodiments, the recesses may have an
average depth that is about 10 mil. In one embodiment, the recesses cover
about 5
percent of the surface area of the outer surface. In other embodiments, the
recesses
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may cover greater than about 7.5, 10, 15, 20, 25, and 50 percent of the
surface area
of the outer surface.
In some embodiments, the film layer comprises a polymeric material
having high moisture barrier properties, such as a water vapor permeability
that is
less than about 0.2 grams/day/100 in2 at 1000 F, 90% relative humidity as
measured
according to ASTM F1249-01. In other embodiments, the film layer may
comprise a polymeric material having low barrier properties, such as a water
vapor
permeability that is greater than about 0.3 grams/day/100 in2 at 100 F, 90%
relative humidity as measured according to ASTM F1249-01. In some
embodiments, the film layer has a water vapor permeability that is greater
than
about 0.2, .23, .25, or.28 grams/day/100 in2 at 100 F, 90% relative humidity
as
measured according to ASTM F1249-01. In some embodiments, it may be
desirable for the underlayment material to have a high water vapor
permeability.
For instance, a high water vapor permeability may permit fluids to quickly
migrate
through the underlayment material and into the fluid pathways. Thereafter the
fluid may migrate through the fluid pathways so that it can efficiently and
quickly
escape the flooring system.
The film layer may include one or more thermoplastic polymers including
polyolefins, polystyrenes, polyurethanes, polyvinyl chlorides, polyesters, and
ionomers provided that the desired properties of the film layer may be
maintained.
Suitable polyolefins for use as the film layer may include LLDPE, low
density polyethylene, high density polyethylene, metallocene catalyzed
polyethylene, polypropylene, and oriented polypropylene, ethylene homo- and co-
polymers and propylene homo- and co-polymers. Ethylene homopolymers include
high density polyethylene ("HDPE") and low density polyethylene ("LDPE").
Ethylene copolymers include ethylene/alpha-olefin copolymers ("EAOs"),
ethylene/unsaturated ester copolymers, and ethylene/(meth)acrylic acid.
("Copolymer" as used in this application means a polymer derived from two or
more types of monomers, and includes terpolymers, etc.).
EAOs are copolymers of ethylene and one or more alpha-olefins, the
copolymer having ethylene as the majority mole-percentage content. In some
embodiments, the comonomer includes one or more C3-C2o alpha-olefins, more
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preferably one or more C4-C12 alpha-olefins, and most preferably one or more
C4-
C8 alpha-olefins. Particularly useful alpha-olefins include 1-butene, 1-
hexene, 1-
octene, and mixtures thereof.
EAOs include one or more of the following: 1) medium density
polyethylene ("MDPE"), for example having a density of from 0.93 to 0.94
g/cm3;
2) linear medium density polyethylene ("LMDPE"), for example having a density
of from 0.926 to 0.94 g/cm3; 3) linear low density polyethylene ("LLDPE"), for
example having a density of from 0.915 to 0.930 g/cm3; 4) very-low or ultra-
low
density polyethylene ("VLDPE" and "ULDPE"), for example having density below
0.915 g/em3; and 5) homogeneous EAOs. Useful EAOs include those having a
density of less than about any of the following: 0.925, 0.922, 0.92, 0.917,
0.915,
0.912, 0.91, 0.907, 0.905, 0.903, 0.9, and 0.898 grams/cubic centimeter.
Unless
otherwise indicated, all densities herein are measured according to ASTM D
1505.
The polyethylene polymers may be either heterogeneous or homogeneous.
As is known in the art, heterogeneous polymers have a relatively wide
variation in
molecular weight and composition distribution. Heterogeneous polymers may be
prepared with, for example, conventional Ziegler Natta catalysts.
On the other hand, homogeneous polymers are typically prepared using
metallocene or other single site-type catalysts. Such single-site catalysts
typically
have only one type of catalytic site, which is believed to be the basis for
the
homogeneity of the polymers resulting from the polymerization. Homogeneous
polymers are structurally different from heterogeneous polymers in that
homogeneous polymers exhibit a relatively even sequencing of comonomers
within a chain, a mirroring of sequence distribution in all chains, and a
similarity
of length of all chains. As a result, homogeneous polymers have relatively
narrow
molecular weight and composition distributions. Examples of homogeneous
polymers include the metallocene-catalyzed linear homogeneous ethylene/alpha-
olefin copolymer resins available from the Exxon Chemical Company (Baytown,
Tex.) under the EXACT trademark, linear homogeneous ethylene/alpha-olefin
copolymer resins available from the Mitsui Petrochemical Corporation under the
TAFMER trademark, and long-chain branched, metallocene-catalyzed
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homogeneous ethylene/alpha-olefin copolymer resins available from the Dow
Chemical Company under the AFFINITY trademark.
Another useful ethylene copolymer is ethylene/unsaturated ester
copolymer, which is the copolymer of ethylene and one or more unsaturated
ester
monomers. Useful unsaturated esters include: 1) vinyl esters of aliphatic
carboxylic
acids, where the esters have from 4 to 12 carbon atoms, and 2) alkyl esters of
acrylic or methacrylic acid (collectively, "alkyl (meth)acrylate"), where the
esters
have from 4 to 12 carbon atoms.
Representative examples of the first ("vinyl ester") group of monomers
include vinyl acetate, vinyl propionate, vinyl hexanoate, and vinyl 2-
ethylhexanoate. The vinyl ester monomer may have from 4 to 8 carbon atoms,
from 4 to 6 carbon atoms, from 4 to 5 carbon atoms, and preferably 4 carbon
atoms.
Representative examples of the second ("alkyl (meth)acrylate") group of
monomers include methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl
acrylate, hexyl acrylate, and 2-ethylhexyl acrylate, methyl methacrylate,
ethyl
methacrylate, isobutyl methacrylate, n-butyl methacrylate, hexyl methacrylate,
and
2-ethylhexyl methacrylate. The alkyl (meth)acrylate monomer may have from 4 to
8 carbon atoms, from 4 to 6 carbon atoms, and preferably from 4 to 5 carbon
atoms.
The unsaturated ester (i.e., vinyl ester or alkyl (meth)acrylate) comonomer
content of the ethylene/unsaturated ester copolymer may range from about 3 to
about 18 weight %, and from about 8 to about 12 weight %, based on the weight
of
the copolymer. Useful ethylene contents of the ethylene/unsaturated ester
copolymer may include the following amounts: at least about 82 weight %, at
least
about 85 weight %, at least about 88 weight %, no greater than about 97 weight
%,
no greater than about 93 weight %, and no greater than about 92 weight %,
based
on the weight of the copolymer.
Representative examples of ethylene/unsaturated ester copolymers may
include ethylene/methyl acrylate, ethylene/methyl methacrylate, ethylene/ethyl
acrylate, ethylene/ethyl methacrylate, ethylene/butyl acrylate, ethylene/2-
ethylhexyl methacrylate, and ethylene/vinyl acetate.
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Another useful ethylene copolymer is ethylene/(meth) acrylic acid, which is
the copolymer of ethylene and acrylic acid, methacrylic acid, or both.
Useful propylene copolymer includes propylene/ethylene copolymers
("EPC"), which are copolymers of propylene and ethylene having a majority
weight % content of propylene, such as those having an ethylene comonomer
content of less than 10%, preferably less than 6%, and more preferably from
about
2% to 6% by weight.
lonomer is a copolymer of ethylene and an ethylenically unsaturated
monocarboxylic acid having the carboxylic acid groups partially neutralized by
a
metal ion, such as sodium or zinc, preferably zinc. Useful ionomers may
include
those in which sufficient metal ion is present to neutralize from about 15% to
about
60% of the acid groups in the ionomer. The carboxylic acid is preferably
"(meth)acrylic acid"--which means acrylic acid and/or methacrylic acid. Useful
ionomers include those having at least 50 weight % and preferably at least 80
weight % ethylene units. Useful ionomers also include those having from 1 to
20
weight percent acid units. Useful ionomers are available, for example, from
Dupont Corporation (Wilmington, Del.) under the SURLYN trademark.
The film layer may have a composition such that any one of the above
described polymers comprises at least about any of the following weight
percent
values: 30, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100% by weight
of the
layer. Film layer may have a single layer construction, or may be formed from
multiple layers for improved moisture barrier properties. In one embodiment
the
film layer may be formed from substantially the same polymer, such as low
density
polyethylene, as is used to form foam layer, or from a different polymer which
is
adhered to the foam layer. In other embodiments, the foam layer may be formed
from a low density form of a polymer, while film layer may be formed from a
high
density form of the same polymer.
The thickness of the film layer is selected to provide sufficient material to
permit the formation of the plurality of recesses in the outer surface. The
film
layer may have a thickness of at least about any of the following values: 1
mils,
1.25 mils, 1.5 mils, 2 mils, 2.5 mils, 3 mils, 5 mils, 10 mils, and 20 mils.
The film
layer may have a thickness ranging from about 3 to about 20 mils, more
preferably
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from about 5 to about 15 mils, and still more preferably about 10 mils.
Further, the
thickness of the film layer as a percentage of the total thickness of the
underlayment material may range (in ascending order of preference) from about
1
to about 50 percent, from about 5 to about 45 percent, from about 10 to about
45
percent, from about 15 to about 40 percent, from about 15 to about 35 percent,
and
from about 15 to about 30 percent. The film layer may have a thickness
relative to
the thickness of the underlayment material of at least about any of the
following
values: 1%, 5%, 10%, 20%, and 30%.
The foam layer may comprise a variety of different foamed polymeric
materials including polyolefins. Suitable polyolefins may include polyethylene
resins, including polyethylene homopolymers and copolymers. Useful
polyethylene homopolymers include low-density polyethylene (LDPE), linear low-
density polyethylene (LLDPE), and high-density polyethylene (HDPE).
Polyethylene copolymers may include homogeneous ethylene/alpha-olefin
copolymers, such as metallocene/single-site catalyzed copolymers of ethylene
and
one or more C3 to Clo alpha-olefin comonomers, or heterogeneous Ziegler-Natta
catalyzed ethylene/alpha-olefin copolymers. Other ethylene copolymers include
propylene, higher olefins and carboxylic acids and esters. Various ethylene
copolymers are used in which the second comonomer is a carboxylic acid or
ester
such as vinyl acetate, acrylic acid, methacrylic acid, methacrylate and ethyl
acrylate. Ethylene vinyl acetate (EVA) copolymers with vinyl acetate content
ranging up to 30% weight could be used copolymers, such as homogeneous
ethylene/alpha-olefin copolymers, heterogeneous Ziegler-Natta catalyzed
ethylene/alpha-olefin copolymers, and ethylene vinyl acetate (EVA) copolymers.
Suitable polyolefin resins may also include polypropylene homopolymers and
copolymers.
The foam layer provides many of the cushioning characteristics of the
underlayment material. The thickness and density of the foam layer may be
selected so that the underlayment material has the desired cushioning
properties.
In one embodiment the foam layer has a density from about 0.5 to 15 pcf. In
other
embodiments, the foam layer has a density that is from about 1.5 to 3.0 pcf,
1.7 to
2.5 pcf, and from 1.9 to 2.2 pcf. The thickness of the foam layer may range
from
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about 0.01 to 3 inches, 0.1 to 2.0 inches, and from 0.75 to
1.5 inches. In one embodiment, the foam layer has a density
from about 1.0 to 2.2 pcf and a thickness between about 0.20
to 1.5 inches.
In some embodiments, the foam layer may include a
plurality of spaced apart ribs that extend at least
partially along the length of the foam layer. The ribs may
provide channels through which a fluid may migrate to the
edges of the flooring system. Floor underlayment materials
having a plurality of ribs are discussed in greater detail
in commonly assigned U.S. Patent Applications Publication
Nos. 2005/0106378 and 2005/0158517.
In some embodiments, the film layer may also
include one or more additives, such as antioxidants,
anti-corrosion agents, UV stabilizers, fire retardants, fire
resistants, anti-bacterial agents, anti-microbial agents,
anti-fungal agents, anti-static agents, biostabilizers
and/or other functional additives depending on the
commercial application of the laminate.
The underlayment material may be used in a wide
variety of applications including flooring applications. As
discussed above, the underlayment material may be used in
finished flooring applications where it may be desirable to
prevent water from accumulating between the floor and the
subfloor. Finished floors may include one or more of wood
planks, parquet flooring, wood laminate flooring, or wood-
block flooring. In one alternative embodiment the floor may
comprise a laminate wood floor including wood laminates
which are commercially available. In other embodiments, the
underlayment material may be used in conjunction with other
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types of flooring systems including linoleum and tile
floors.
In one embodiment, the floor may comprise wood or
laminate planks that are positioned side-by-side on the
underlayment material. In one alternative embodiment, the
planks may fit together by means of tongue-in-groove
arrangement. In some embodiments, the floor may be a so-
called "floating floor".
The subfloor may include precast or preformed
concrete, poured concrete, or reinforced concrete. In one
embodiment, the flooring system comprises a wood subfloor in
combination with an underlayment material having low barrier
properties. In such an embodiment, a low barrier
underlayment material may help
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permit the escape of fluid from within the flooring system and thereby prevent
the
accumulation of moisture between the wood subfloor and the underlayment
material.
The flooring system may be assembled in any known manner. In one
embodiment, the underlayment material is positioned on a concrete subfloor in
a
free-lying manner. The floor may be in the form of strips of wood or laminate
planks. In some embodiments, the underlayment material may not be adhered to
the concrete subfloor. In one alternative embodiment, the bottom of the foam
layer contacts the top surface of concrete subfloor and the outer surface of
the film
layer may be at least partially in contact with the underside of the floor.
Planks of
laminate wood flooring may be positioned on the underlayment material in a
free-
lying manner. Planks may fit together by means of tongue-in-groove arrangement
and in some embodiments may be glued together. The outer surface of the film
layer contacts the bottom surface of laminate wood flooring.
The following examples are provided for the purpose of illustration only
and should not be construed as limiting the invention in any way.
EXAMPLES
Example 1:
A twin-screw extruder was used for making a Sample A foam as mentioned
in Table 1. A 2.0 MI, 0.919 g/cc LDPE resin was used. The resin rate was 405
lb/hr which included 10% of recycled material. The aging modifier (blend of
glycerol monostearate and monodiethanolamide) was added at 5.2 lb/hr. Talc
masterbatch from Colortech was added at 7.6 lb/hr along with black coloring
agent. To expand the foam, propane was injected as a physical foaming agent.
The propane was mixed with the LDPE and cooled prior to exiting the die. The
cooled mixture was extruded through an annular sheet die. The melt temperature
was at 232 F and the die pressure was at 610 psi. The final density is about
1.85
pounds per cubic feet having a thickness of 0.155 inch. Then, the foam was
wound
in a forrn of a roll and cured.
After the foam was cured, a 10 mil thick film was extrusion coated on top
of the foam and then embossed using the cast lamination process. A single
screw
extruder was used to cast extrude a 10 mil LDPE film. The cured foam was
passed
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through an embossing roll to produce a plurality of recesses on the surface of
the
film layer. The embossing roll imprinted a plurality of recesses on the
surface of
the film layer in a diamond-shaped pattern similar to the one shown in FIG. 1
a.
For example, the area of each diamond was approximately 0.014 in2. Similarly,
the other patterns can be embossed. The same grade LDPE as described before
along with 2% carbon black were used to produce a black-colored embossed film.
The film contained about 50% of virgin resin and about 50% of recycled
material
from the same resin. The recycled content in the film can be increased up to
100%.
Table 1
Units Sample A Test Method
Film thickness mil) 10 --
Foam thickness (inch) 0.155 --
Avera e Recess De th mil) 17 --
Compression strength (psi) 3.1 ASTM D3575-00 Suffix D
25%
Compression strength (psi) 12.6 ASTM D3575-00 Suffix D
50%
Tensile MD (psi) 125.4 ASTM D412-98
Tensile cMD (psi) 104.5 ASTM D412-98
Tear MD (psi) 23.8 ASTM D624-00
Tear cMD (psi) 32.0 ASTM D624-00
MD Elongation (%) 112.9 ASTM D412-98
cMD Elongation (%) 93.2 ASTM D412-98
Compression Set (%) 35.0 ASTM D3575-00 Suffix B
Thermal Stability (%) 0.3 ASTM D3575-00 Suffix S
WVTR* (g/day)100inZ 0.23 ASTM F1249-01
STC Rating No units 54 ASTM E90
IIC Rating No units 59 ASTM E492
*Water Vapor Transmission Rate (WVTR) was measured at 100 F and 90% relative
huniidity
Many modifications and other embodiments of the inventions set forth
herein will come to mind to one skilled in the art to which these inventions
pertain
having the benefit of the teachings presented in the foregoing descriptions
and the
associated drawings. Therefore, it is to be understood that the inventions are
not to
be limited to the specific embodiments disclosed and that modifications and
other
embodiments are intended to be included within the scope of the appended
claims.
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Although specific terms are employed herein, they are used in a generic and
descriptive sense only and not for purposes of limitation.
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