Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHODS OF PROVIDING WATER PROTECTION TO FLOOR STRUCTURES AND
FLOOR STRUCTURES FORMED BY THE SAME
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention generally relates to methods of providing improved
flooring
sheets with increased water protection and increased flatness and the floor
structures
formed by such methods.
Description of the Related Art
Current methods for constructing floor structures of buildings such as
residential
homes include attaching floor sheathing such as plywood or oriented strand
board (OSB)
to a floor frame. A flooring material such as wood, tile, or vinyl flooring is
then installed
over the floor sheathing. Water sheathing underlayments (e.g., asphalt felt
paper) may
also be added between the floor sheathing and the flooring material in order
to impede
water migration from the floor cavity below the floor sheathing to the
flooring material,
which may damage flooring materials such as wood flooring, and in order to
impede
water migration from the flooring material to the sheathing and other floor
structure, which
may damage the sheathing and other floor structure.
It would be desirable to provide other methods for protecting floor structures
from
water as well as the floor structures produced by such methods.
SUMMARY OF THE INVENTION
In one aspect, a method of providing water protection to a floor structure of
a
building is provided. The method comprises (a) providing one or more water
resistant
floor sheathing panels, each panel comprising a wood sheet product and a
nonwoven
fabric mat adhered to the wood sheet product, and (b) installing the floor
sheathing
panel(s) on a floor structure of a building such that the nonwoven mat of each
panel faces
upwardly. Each floor sheathing panel is produced by subjecting a wood sheet
product
and a "B" stage condition nonwoven fabric mat to sufficient heat and pressure
to
complete the cure of the binder in the mat and to adhere the mat to the wood
sheet
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product, the "B" stage condition mat comprising fibers bonded together with a
resin binder
that is only partially cured.
In another aspect, a floor structure of a building is provided that comprises
a
plurality of water resistant floor sheathing panels attached to a floor frame
of a building as
a base layer. Each panel comprises a wood sheet product and a nonwoven fabric
mat
adhered to the wood sheet product; each floor sheathing panel is produced by
subjecting
a wood sheet product and a "B" stage condition nonwoven fabric mat to
sufficient heat
and pressure to complete the cure of the binder in the mat and to adhere the
mat to the
wood sheet product, with the "B" stage condition mat comprising fibers bonded
together
with a resin binder that is only partially cured. The nonwoven mat of each
panel faces
upwardly, and a flooring material is attached over the nonwoven mats of the
base layer of
floor sheathing panels.
In a further aspect, a method of providing water protection to a floor
structure of a
building is provided that comprises (a) providing one or more water resistant
floor
sheathing panels each comprising a wood sheet product, a nonwoven fabric mat
adhered
to the wood sheet product, and an organic waterproof coating adhered to the
nonwoven
fabric mat; and (b) installing the floor sheathing panel(s) on a floor
structure of a building
such that the nonwoven mat of each panel faces upwardly.
In yet another aspect, a floor structure of a building is provided that
comprises a
plurality of water resistant floor sheathing panels attached to a floor frame
of a building as
a base layer. Each panel comprises a wood sheet product, a nonwoven fabric mat
adhered to the wood sheet product, and an organic waterproof coating adhered
to the
nonwoven fabric mat, with the waterproof coating of each panel facing
upwardly. A
flooring material is attached over the coated nonwoven fabric mats of the base
layer of
floor sheathing panels.
In yet a further aspect, a method of providing water protection to a floor
structure
of a building is provided comprising the steps of (a) providing one or more
water resistant
floor sheathing panels, each panel comprising a wood sheet product and a
nonwoven
fabric mat adhered to the wood sheet product and (b) installing the floor
sheathing
panel(s) on a floor structure of a building such that the nonwoven mat of each
panel faces
upwardly. Each panel is produced by (1) forming a composite mat comprising:
(i) a mat
formed from a furnish comprising wood particles and a binder, the mat having a
first face
and a second face; and (ii) a nonwoven fabric mat contacting the first face of
the mat
formed from the furnish; and (2) subjecting the composite mat to sufficient
heat and
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pressure to form a floor sheathing panel comprising a wood sheet product
having a first
face, a second face, and edges with the nonwoven fabric mat adhered to the
first face of
the wood sheet product.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 illustrates the results of testing, for various properties, four
types of test
boards comprising oriented strand board with different nonwoven fabric mat
facings as
well as an OSB control as explained below.
Figure 2 illustrates a summary of the test results from Figure 1.
Figure 3 illustrates the strength test results for boards comprising OSB with
glass
mat facings that were made using furfuryl alcohol formaldehyde (FAF) binder
with an
added water repellant (referred to in the figure as "Enhanced"). The figure
also illustrates
comparative results for an OSB control ("Control") that was tested as well as
the
Canadian Standards Association (CSA) minimum standards ("Standard") for OSB
for
each of the tests.
Figure 4 illustrates the resistance to moisture test results for boards
comprising
OSB with glass mat facings made using FAF binder and a water repellant
(Enhanced).
The figure also illustrates comparative results for an OSB control (Control)
that was
tested as well as the Canadian Standards Association (CSA) minimum standards
(Standard) for OSB for each of the tests.
Figure 5 illustrates strength test results for boards comprising OSB with
glass mat
facings that were made using phenol formaldehyde (PF) binder (Enhanced). The
figure
also illustrates the comparative Control and Standard values listed in Figure
3.
[0001] Figure 6 illustrates the resistance to moisture test results for boards
comprising
OSB with glass mat facings made using PF binder (Enhanced). The figure also
illustrates
the comparative Control and Standard values listed in Figure 4.
Figure 7 illustrates the strength test results for boards comprising OSB with
polyester spunbond mat facings that were made using PF binder (Enhanced). The
figure
also illustrates the comparative Control and Standard values listed in Figure
3.
Figure 8 illustrates the resistance to moisture test results for boards
comprising
OSB with polyester spunbond mat facings that were made using PF binder
(Enhanced).
The figure also illustrates the comparative Control and Standard values listed
in Figure 4.
Figure 9 illustrates the strength test results for boards comprising OSB with
a
glass mat facings that were made using FAF binder (Enhanced). The figure also
illustrates the comparative Control and Standard values listed in Figure 3.
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Figure 10 illustrates the resistance to moisture test results for boards
comprising
OSB with glass mat facings made using FAF binder. The figure also illustrates
the
comparative Control and Standard values listed in Figure 4.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention relates to methods of providing water protection to
floor
structures as well as the improved floor structures formed by the methods.
In general, the methods comprise providing one or more water resistant floor
sheathing/underlayment panels and installing the panei(s) on a floor structure
of a
building. Each of the floor sheathing panels comprises a wood sheet product
and a
nonwoven fabric mat adhered to at least one side of the wood sheet product. As
explained below, the nonwoven fabric mats of the floor sheathing panels
provide water
resistance to the sheathing panels and therefore to the floor structures and
buildings in
which they are installed. That is, the nonwoven fabric mats provide water
protection to
the wood sheet product of the floor sheathing panels themselves, and the water
resistant
floor sheathing panels provide water protection to the rest of the floor
structure (including
the flooring material, floor frame, etc.) by impeding water migration (e.g.,
from above to
below the floor sheathing panels and from below to above the floor sheathing
panels). In
some embodiments, the floor sheathing panels may include a nonwoven fabric mat
adhered to two sides of the wood sheet product (e.g., to opposing faces of the
wood
sheet product).
Water protection may be provided to a floor of a building by providing one or
more
water resistant floor sheathing panels and installing the floor sheathing
panel(s) on a floor
structure of the building such that the nonwoven mat of each panel faces
upwardly (i.e.,
toward the ceiling of the room in which the floor structure is located). A
floor structure of
a building may comprise, for example, a frame or other structure of the floor,
and
installation of the floor sheathing panels may comprise attaching the panels
to the frame
of the floor structure. In some embodiments, the floor sheathing panels may
comprise a
nonwoven mat adhered to both faces of the wood sheet product such that one mat
faces
upwardly toward the ceiling and one mat faces downwardly. The second nonwoven
mat
may be used, for example, to provide further water protection from water
sources within
the floor structure (e.g., a pipe within the floor structure).
The methods of providing water protection to floor structures may further
comprise
attaching or installing a flooring material to or on top of the nonwoven mat
of the floor
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sheathing panel(s) that faces upwardly. The flooring material may be any type
of flooring
material such as, for example, tile, wood flooring, cork flooring, carpet,
etc.
Each of the floor sheathing panels typically comprises two faces with at least
one
nonwoven fabric mat on one of the faces. Each of the floor sheathing panels
further
comprises outer edges. The outer edges of the floor sheathing panels may
include self-
adhesive tape covered by one or more strips that are removable from the self-
adhesive
tape. The floor sheathing panels may also have tongue-and-groove edges for
installation. For example, the panels may include a tongue on a first outer
edge and a
corresponding groove on a second, opposite outer edge such that multiple
panels may be
connected together by interconnecting the tongues and grooves of adjacent
panels. In
such embodiments, the at least one mat and the wood sheet product are
typically
coterminous at the outer edges of the floor sheathing panel (i.e., outer edges
of the mat
and the wood sheet product are coterminous). In some embodiments, however, the
outer
edges of the wood sheet product and the at least one nonwoven mat are not
coterminous. For example, the at least one nonwoven fabric mat of each floor
sheathing
panel may include an overlay portion extending beyond one or more edges of the
wood
sheet product to which it is adhered. Such an overlay portion may include a
pressure
sensitive adhesive.
When installing the floor sheathing panel(s) with self-adhesive tape, the
removable strip or strips may be removed from the self-adhesive tape of one of
the floor
sheathing panels and joined with the floor structure or with another floor
sheathing panel
(or self-adhesive tape on another panel) so as to form a seal. When installing
the floor
sheathing panel(s) with an overlay portion of nonwoven mat having a pressure
sensitive
adhesive, the overlay portion of one of the floor sheathing panels may be
adhered to the
floor structure or with another floor sheathing panel so as to form a seal. A
seal between
adjacent floor sheathing panels or between a floor sheathing panel and an
floor structure
may also be formed using a sealing material such as, for example, epoxy resin,
mastic, or
caulk.
In some embodiments, the methods may consist of providing the water resistant
floor sheathing panel(s) and installing the panel(s) on a floor structure.
That is, in such
embodiments, no other water protection (such as asphalt felt paper or Tyvek
wrap) for
the floor structure will be supplied. In some of these embodiments, the step
of installing
the floor sheathing panel(s) may include forming a seal between the edges of
adjacent
floor sheathing panel(s) and/or forming a seal between the edges of the floor
sheathing
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panels and the floor structure (e.g., floor frame); however, in other of these
embodiments,
the step of installing the floor sheathing panel(s) may not include forming a
seal between
the edges of the floor sheathing panel(s).
The floor structures formed by the methods generally comprise a plurality of
water
resistant floor sheathing panels attached to a floor frame of a building as a
base layer. As
explained above, each panel comprises a wood sheet product and at least one
nonwoven
fabric mat adhered to a face of the wood sheet product. The at least one
nonwoven mat
of each panel faces upwardly. The floor structure also comprises a flooring
material (e.g.,
tile, wood flooring, cork flooring, etc.) attached over the nonwoven mats of
the base layer
of floor sheathing panels.
The wood sheet products used to form the floor sheathing panels may be any
type
of wood product including, but not limited to particle board, chip board,
oriented strand
board (OSB), plywood, and hardboard.
The nonwoven mats used to form the floor sheathing panels comprise fibers
bonded together with a binder. In some embodiments, the nonwoven mats may
consist
of fibers and binder, and in other embodiments the nonwoven mats may include
additional additives, such as pigments, dyes, flame retardants, water
resistant agents,
and/or other additives. Water resistant agents (i.e., water repellants) that
may be used
include, but are not limited to, stearylated melamine, fluorocarbons, waxes,
asphalt,
organic silicone, rubber, and polyvinyl chloride.
The fibers of the nonwoven mats may comprise glass fibers, polyester fibers
(e.g.,
polyester spunbonded fibers), polyethylene terephthalate (PET) fibers, other
types of
synthetic fibers (e.g., nylon, polypropylene, etc.), carbon fibers, ceramic
fibers, metal
fibers, or mixtures thereof. The fibers in the nonwoven mats may consist
entirely of one
of the previously mentioned types of fibers or may comprise one or more of the
previously
mentioned types of fibers along with other types of fibers such as, for
example, cellulosic
fibers or fibers derived from cellulose. The nonwoven mat can also be
reinforced, either
within itself or on the surface with parallel strands, diagonal or box shaped
scrim of
reinforcements. These additional reinforcements may be glass yarn or
continuous
filaments of plastic or metal.
The fibers may have various fiber diameters and lengths dependent on the
strength and other properties desired in the mat. When polyester fibers are
used, it is
preferred that the denier of a majority of the fibers is in the range of 3 to
5. When glass
fibers are used, it is preferred that a majority of the glass fibers have
diameters in the
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range of 6 to 23 microns, more preferably in the range from 10 to 19 microns,
even more
preferably in the range of 11 to 16 microns. The glass fibers can be any type
of glass
including E glass, C glass, T glass, S glass, and other types of glass with
good strength
and durability in the presence of moisture.
Various binders may be used to bond the fibers together. Typically, binders
are
chosen that can be put into aqueous solution or emulsion latex and that are
water
soluble. As explained more fully below, the binders may be completely cured
when
forming the nonwoven mats or the binders may be "B" staged (i.e., only
partially cured).
When the binder in a nonwoven mat will be "B" staged, the binders preferably
bind well to
wood. Examples of binders that may be used for forming nonwoven mats with "B"
staged
binder include, but are not limited to, a furfuryl alcohol based resin, a
phenol
formaldehyde resin, a melamine formaldehyde resin, and mixtures thereof. When
the
mats will be completely formed (i.e., the binder will not be "B" staged), the
binders may
include, but are not limited to urea formaldehyde, melamine formaldehyde,
phenol
formaldehyde, acrylics, polyvinyl acetate, epoxy, polyvinyl alcohol, or
mixtures thereof.
Binders may also be chosen such that the binder is "formaldehyde free",
meaning that the
binder contains essentially no formaldehyde (i.e., formaldehyde is not
essential, but may
be present as an impurity in trace amounts). Binder that may be used to
provide
formaldehyde free nonwoven mats include, but are not limited to polyvinyl
alcohol,
carboxy methyl cellulose, lignosulfonates, cellulose gums, or mixtures
thereof. The
nonwoven mat binder can also include a formaldehyde scavenger, which are
known.
Using formaldehyde scavengers in the binder dramatically slows the measurable
formaldehyde release rate from the product.
Similarly, the nonwoven binder can include antimicrobial additives. Examples
of
suitable antimicrobial materials include zinc 2-pyrimidinethiol-1-oxide; 1-[2-
(3,5-dichloro-
phenyl)-4-propyl-[1,3]dioxo-lan-2-ylmethyl]-1 H-[1,2,4]triazole; 4,5-dichloro-
2-octyl-
isothiazolidin-3-one; 2-octyl-isothiazolidin-3-one; 5-chloro-2-(2,4-dichloro-
phenoxy)-
pheno-1,2-thiazol-4-yl-lH-benzoimidazole; 1-(4-chloro-phenyl)-4,4-dimethyl-3-
[1,2,4]
triazol-4-ylmethyl-pentan-3-ol; 10,10' oxybisphenoxarsine; 1-(diiodo-
methanesulfonyl)-4-
methyl-benzene and mixtures thereof. By encapsulating or surface covering the
two
surfaces of the wood sheathing panel with antimicrobial skins the entire
product becomes
more mold and mildew resistant. The skins can also include an additive such as
borates
that resist termites or other pests and provides additional fire resistance.
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The nonwoven fabric mats may be made with varying ratios of the amount of
fiber
to the amount of binder in the mat. For example, in the "B" staged mats, it is
preferable
that the mats contain about 25-75 weight percent fibers and about 15-75 weight
percent
binder, more preferably 30-60 weight percent fibers and 40-70 weight percent
binder. In
mats made from formaldehyde free binder, it is preferred that the mats contain
about 93-
99.5 weight percent fibers and about 0.5-4 weight percent binder. However,
other ratios
of fiber to binder in the mats may be used for "B" staged mats, formaldehyde
free mats,
as well as non-"B" staged mats and other mats.
The nonwoven fabric mats may also be made to have varying thicknesses.
Typical thicknesses for the mats range from 0.020 inches to 0.125 inches,
although
thicker and thinner mats may be used.
The nonwoven mats may include a coating to impart water resistance (or
waterproofness), flame resistance, insect resistance, mold resistance, a
smooth surface,
increased or reduced surface friction, desirable aesthetics, and/or other
surface
modifications. Coatings that may be used for waterproofing include organic
waterproof
coatings such as asphalt, organic silicone, rubber, and polyvinyl chloride.
The coatings
are preferably on the exterior side of the mats (i.e., the side that is not
bound to the wood
sheet product).
Any method for making nonwoven fabric mats may be used to provide the mats.
Processes for making nonwoven fabric mats are well known. U.S. Pat. Nos.
4,112,174,
4,681,802 and 4,810,576, the entire contents of which are hereby incorporated
herein by
reference, describe methods of making nonwoven glass fabric mats.
One technique for making the nonwoven mats that may be used is forming a
dilute aqueous slurry of fibers and depositing the slurry onto an inclined
moving screen
forming wire to dewater the slurry and form a wet nonwoven fibrous mat, on
machines
like a HydroformerTM manufactured by Voith--Sulzer of Appleton, Wis., or a
DeltaformerTM
manufactured by Valmet/Sandy Hill of Glenns Falls, N.Y. After forming a web
from the
fibrous slurry, the wet, unbonded mat is transferred to a second moving screen
running
through a binder application saturating station where the binder in aqueous
solution is
applied to the mat. The aqueous binder solution is preferably applied using a
curtain
coater or a dip and squeeze applicator. The excess binder is removed, and the
wet mat
is transferred to a moving oven belt that runs through a convection oven where
the
unbonded, wet mat is dried and cured, bonding the fibers together in the mat.
The mat
may be fully cured or may be cured to only a "B" stage. In the drying and
curing oven the
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mat is heated to temperatures of up to about 350 degrees F., but this can vary
from about
210 degrees F. to as high as any temperature that will not deteriorate the
binder or, when
a "B" stage cure is desired, to as high as any temperature that will not cure
the binder
beyond "B" stage cure. The treatment time at these temperatures can be for
periods
usually not exceeding I or 2 minutes and frequently less than 40 seconds. When
curing
the binder to a "B" stage, the lower the temperature that is used for the
cure, the longer
time required to reach "B" stage cure, although a temperature is normally
selected such
that the binder will reach "B" stage cure in no more than a few seconds.
The floor sheathing panels may be formed from the nonwoven fabric mats and the
wood sheet products by attaching a nonwoven fabric mat to a face of a wood
sheet
product. The nonwoven fabric mat may be attached to a wood sheet product
either after
completion of manufacture of the wood sheet product or during manufacture of
the wood
sheet product. When using a completed wood sheet product and a nonwoven mat
that
has been completely cured (i.e., when the nonwoven mat is not in a "B" stage
condition),
an adhesive may be used to adhere the completed wood sheet product and the
nonwoven mat together using sufficient pressure and heat to cure the adhesive.
When
using a completed wood sheet product and a nonwoven mat that is in a "B" stage
condition, the completed wood sheet product and the nonwoven mat with a "B"
stage
condition binder are placed in contact and then subjected to sufficient heat
and pressure
to adhere the mat to the wood sheet product and to finish curing the "B"
staged binder in
the mat.
The floor sheathing panels may also be formed during manufacture of a wood
sheet product such as OSB that comprises wood particles bonded together with
binder
using elevated heat and pressure. During formation of such a wood sheet
product, a
furnish comprising a mixture of wood particles and binder is formed into an
oriented or
nonoriented mat, which is then subjected to sufficient heat and pressure to
cure the
binder and form the completed wood sheet product. The particles may be in any
form
including, but not limited to, chips, shavings, fibers, flakes, wafers,
strands, and
combinations thereof. The binder used to bond the wood particles together may
be any
binding agent that binds the particles together to form the wood sheet product
when
subjected to heat and pressure including, for example, phenol formaldehyde
resin, urea
formaldehyde resin, melamine formaldehyde resin, and the like.
In order to form a floor sheathing panel during manufacture of a wood sheet
product (rather than after completion of the wood sheet product), a composite
mat is
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formed using at least one nonwoven fabric mat and a furnish comprising wood
particles
and a binder. The composite mat comprises (1) a mat formed from the furnish
having a
first face and a second face and (2) the nonwoven fabric mat contacting the
first face of
the mat formed from the furnish. When two nonwoven fabric mats are used with
the
furnish to form the composite mat, the composite mat may comprise (1) a mat
formed
from the furnish having a first face and a second face, (2) a first nonwoven
fabric mat
contacting the first face of the mat formed from the furnish, and (3) a second
nonwoven
fabric mat contacting the second face of the mat formed from the furnish. The
composite
mat could be formed by forming the mat from the furnish and then contacting
the at least
one nonwoven fabric mat to one of the faces of the mat formed from the
furnish, or the
composite mat could be formed by forming the mat from the furnish while the
furnish is in
contact with the at least one nonwoven fabric mat such that the nonwoven
fabric mat is in
contact with a face of the resulting mat formed from the furnish. After being
formed, the
composite mat is subjected to sufficient heat and pressure to form a floor
sheathing panel
comprising a wood sheet product having a first face, a second face, and edges
(made
from the mat formed from the furnish) and the nonwoven fabric mat or mats
adhered to
the face or faces of the wood sheet product. That is, the composite mat is
subjected to
sufficient heat and pressure to form the completed/cured wood sheet product
from the
mat formed from the furnish as well as to adhere the nonwoven mat thereto.
Thus, only
one application of heat and pressure is used, rather than forming the wood
sheet product
using a first application of heat and pressure and then performing a second
application of
heat and pressure to adhere a nonwoven fabric mat to the wood sheet product.
The
press times, temperatures, and pressures used to form the floor sheathing
panel may
vary depending upon the desired thickness and density of the panel, the binder
or binders
that are used, as well as other variable factors.
When a floor sheathing panel is formed using a one-step application of heat
and
pressure to a composite mat, "B" staged nonwoven fabric mats or fully cured
nonwoven
fabric mats may be used to form the floor sheathing panel. When a "B" staged
nonwoven
fabric mat is used in the composite mat, no additional binder or adhesive is
typically
needed to adhere the nonwoven mat to the wood sheet product during the one-
step
application of heat and pressure (although such additional binder or adhesive
may be
used if desired); the pressure and heat that the composite mat is subjected to
is sufficient
to complete the cure of the binder in the "B" staged nonwoven mat and adhere
the
nonwoven fabric mat to the wood sheet product. When a nonwoven fabric mat is
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that has been completely cured (i.e., when the nonwoven mat is not in a "B"
stage
condition), additional binder or adhesive may be used to adhere the nonwoven
mat to the
wood sheet product that is formed during the one-step application of heat and
pressure;
the pressure and heat that the composite mat is subjected to is sufficient to
complete the
cure of the additional binder or adhesive and adhere the nonwoven mat to the
completed
wood sheet product. Such additional adhesive or binder may be added between
the mat
formed with the furnish (i.e., the mat comprising wood particles and binder)
and the
nonwoven fabric mat, may be added to the furnish before forming the mat with
the
furnish, or may be added to the nonwoven fabric mat.
Methods of making "B" staged nonwoven mats as well as wood laminates using
"B" stage nonwoven mats are described in U.S. Patent Nos. 5,837,620;
6,331,339; and
6,303,207 and U.S. Patent Application Publication No. 2001/0021448, the entire
contents
of which are incorporated by reference herein. Methods of making nonwoven mats
using
formaldehyde free binders as well as wood laminates using such mats are
described in
U.S. Patent Application Publication No. 2003/0008586, the entire content of
which is
incorporated by reference herein.
The nonwoven fabric mats to be used in the floor sheathing panels are chosen
such that they provide water resistance to the sheathing panels. As used
herein, "water
resistance" of a floor sheathing panel and a "water resistant" floor sheathing
panel mean
that the water resistance of the floor sheathing panel is greater than (1) the
water
resistance of the wood sheet product of the floor sheathing panel alone (i.e.,
without the
one or more nonwoven fabric mats adhered to the wood sheet product) and/or (2)
the
water resistance of a wood sheet product of the same type used in the floor
sheathing
panel with comparable dimensions to the completed floor sheathing panel (i.e.,
the same
size as the floor sheathing panel). Such water resistance may be added to the
floor
sheathing panels in a variety of ways such as, for example, (1) by the binder
in the
nonwoven mat, (2) by a water repellant coating (or a waterproof coating) on
the
nonwoven mat, (3) by a water repellant agent (or waterproof agent) added with
the binder
when forming the nonwoven mat, and/or (4) by addition of water repellant (or
waterproof)
fibers (such as polyester fibers) to the nonwoven mat. Other methods of adding
water
repellency to the mats of the floor sheathing panels may also be used. The
addition of
water resistance to the floor sheathing panels may also add or increase the
mold and
mildew resistance of the floor sheathing panels.
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In addition, the nonwoven fabric mats may increase the strength (e.g.,
flexural
strength), dimensional stability, and/or flame resistance of the floor
sheathing panels as
compared to the wood sheet product of the panels alone. That is, the nonwoven
fabric
mat(s) may be chosen such that one or more of these properties in the floor
sheathing
panel is greater than that of the wood sheet product of the floor sheathing
panel without
the one or more nonwoven fabric mats adhered to the wood sheet product.
Furthermore, the nonwoven fabric mats to be used in the floor sheathing panels
may also be chosen such that they provide increased strength (e.g., flexural
strength or
puncture resistance), increased dimensional stability, increased mold
resistance,
increased flame resistance, and/or reduced weight to the floor sheathing panel
as
compared to a wood sheet product of the same type used in the floor sheathing
panel
with comparable dimensions to the completed floor sheathing panel (i.e., as
compared to
a wood sheet product the same size as the floor sheathing panel).
Further, the increased stiffness of the new floor panels with top and bottom
nonwoven skins permits the spacing to be increased while maintaining a flat
floor that is
load bearing and stays flat with no waviness. The stressed skins also reduce
the amount
of swelling that occurs through physical constraint on the edge. This
overcomes a
common problem where unsealed or cut edges suck up water and swell causing an
uneven and visually unacceptable floor surface.
Further, covering one or both sides of the floor sheathing panels with
nonwoven
skins composed of primarily inorganic fibers enhances the fire penetration
resistance and
reduces flame propagation. Additional advantages are also realized as each
nonwoven
skin applied to the wood sheathing panels aids to significantly reduce flaking
and dust. A
double side skinned sheathing panel is considered to exhibit no flaking
compared to a
standard OSB.
Surface finish of the top and bottom of these floor panels can be
significantly
modified by selecting different nonwoven facers. A typical OSB is sanded to
produce a
smooth surface whereas a nonwoven B staged glass mat facer normally generates
a
smooth surface with no sanding.
EXAMPLE
The invention will be further explained by the following illustrative example
that is
intended to be non-limiting.
Various types of test boards were manufactured and tested in order to measure
their strength and moisture resistance. Briefly, the test boards comprised an
oriented
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strand board with nonwoven fabric mats adhered to the faces of the board.
Oriented
strand board (OSB) without nonwoven fabric mats was used as a control and was
tested
for the same properties as the test boards.
A. Boards
The following types of boards were tested, with the number of boards
manufactured listed in parentheses after the description of the type of board:
(1) OSB with glass mat facings made using furfuryl alcohol formaldehyde
(3 boards manufactured);
(2) OSB with glass mat facings made using furfuryl alcohol formaldehyde
with stearylated water repellant added to the binder (2 boards
manufactured);
(3) OSB with glass mat facings made using phenol formaldehyde binder
(2 boards manufactured);
(4) OSB with polyester spunbonded mat facings made using phenol
formaldehyde binder (2 boards manufactured); and
(5) OSB with no nonwoven mat facing (i.e., the control) (2 boards
manufactured).
The "B" staged nonwoven mats used for the boards were formed using a
conventional wet lay process. The basis weight of the glass mats used with the
test
samples was 6 Ibs./100 ft.2, with the mats made with approximately 60% binder
and 40%
fibers. The glass fibers used in the glass mats were E glass fibers having
average fiber
diameters of 16 microns and an average length of 1 inch. In the glass mats
with
stearylated water repellant added to the binder, the mats were made with
approximately
40% fibers, 56% binder, and 4% water repellant. The basis weight of the
polyester
spunbonded mats were 120 g/m2, with the phenol formaldehyde binder applied at
3
Ibs./100 ft2. The polyester spunbond fiber used in the mats had a denier of
approximately
4 dpf.
The test boards and the oriented strand board control boards were prepared
using
a 34" x 34" forming box. To form the OSB control boards, the furnish of wood
strands
and binder was hand formed into mats using the forming box. To form the test
boards,
the furnish of wood strands and binder and the "B" staged nonwoven mats were
hand
formed into composite mats using the forming box such that the nonwoven mats
sandwiched a mat formed by the furnish. The hand formed mats were then pressed
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using a typical OSB press cycle. All parameters were based on typical OSB
commercial
values as summarized in the table below.
Target Dimensions (inches) 28 x 28 x 0.437
Target Density (Ibs./ft. ) 39.0
Mat Construction Oriented
Face/core ratio - 50/50
Resin Type Face: Liquid Phenol Formaldehyde
Core: isocyanate resin (MDI)
Wax Type Slack Wax 1% solids
Press Temperature (degrees 400
Fahrenheit)
The panels were pressed to the target thickness of 0.437". The panels were
pressed for approximately 150 seconds at a press temperature of 400 F. The
resulting
boards were trimmed to approximately 28" x 28".
B. Measurements
Each type of test board and the control boards were measured for the following
properties in order to assess strength and moisture resistance, with the
number of
samples per board that were tested listed in parentheses after the description
of the test:
(1) modulus of rupture (MOR) in the parallel direction of the OSB (MOR
para), measured in pounds per square inch ~psi) (3 samples per board
tested);
(2) modulus of rupture in the perpendicular direction of the OSB (MOR
perp), measured in psi (3 samples per board tested);
(3) modulus of elasticity (MOE) in the parallel direction of the OSB (MOE
para), measured in psi (3 samples per board tested);
(4) modulus of elasticity in the perpendicular direction of the OSB (MOE
perp), measured in psi (3 samples per board tested);
(5) internal bond, measured in psi (6 samples per board tested);
(6) bond durability in the parallel direction of the OSB measured as the
modulus of rupture after 2 hours of boiling a sample of a board,
measured in psi (3 samples per board tested);
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(7) bond durability in the perpendicular direction of the OSB measured as
the modulus of rupture after 2 hours of boiling a sample of a board,
measured in psi (3 samples per board tested);
(8) thickness swell percentage after 24 hours of soaking a sample of a
board in water (2 samples per board tested);
(9) water absorption after 24 hours of soaking a sample of a board in
water, measured as percentage (2 samples per board tested);
(10) linear expansion in the parallel direction of the OSB from oven dry to
saturated using a vacuum pressure soak, measured as percentage (2
samples per board tested);
(11) linear expansion in the perpendicular direction of the OSB from oven
dry to saturated using a vacuum pressure soak, measured as percentage
(2 samples per board tested); and
(12) water vapor transmission, measured in perms (2 samples per board
tested).
Each of properties (1)-(11) listed above was evaluated using Canadian
Standards
Association (CSA) test standard 0437.1-93. Water vapor transmission (i.e.,
property (12)
above) was measured using ASTM Standard Test Method E96.
C. Results
The results of the measurements of the properties of the various boards are
shown in Figure 1. Figure 1 lists the results of the tests, the standard
deviation (sd) of the
tests, and an indication of whether the results for each type of board were
improved
versus the control sample (i.e., OSB Baseline) at a statistically significant
level (i.e., a
95% confidence level) using the Student's T-test (indications were given as
True or
False). Figure 1 also includes an indication for the modulus of rupture (MOR)
and the
modulus of elasticity (MOE) tests of whether the reduction in variation
between the results
for each type of board and the variation of the results for the control sample
boards (i.e.,
OSB Baseline) for these tests were statistically significant with 95%
confidence level
using a Chi-Square test (indications were given as True or False, with True
being an
indication that the variation in the test results were reduced at a
statistically significant
level as compared to the variation in the OSB control boards). Finally, Figure
1 also lists
for some of the tests the CSA standard minimum for OSB.
The results illustrate increased strength and moisture resistance in the test
boards. Figure 2 summarizes the results showing the statistically significant
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improvements that were made to the perpendicular force strength and water
resistance in
the test boards versus the OSB control boards.
Figures 3-10 illustrate the strength and resistance to moisture test results
for the
test boards. The test descriptions listed in bold type indicate those tests
where the listed
test boards had a statistically significant difference from the control boards
at the 95%
confidence level.
While the invention has been described in detail and with reference to
specific
embodiments thereof, it will be apparent to one skilled in the art that
various changes and
modifications can be made without departing from the spirit and scope of the
invention.
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