U.S. patent application number 12/847407 was filed with the patent office on 2010-11-25 for reinforced wood flooring with a discontinuous glue pattern for truck trailers and containers.
This patent application is currently assigned to ROCKLAND FLOORING. Invention is credited to Marc CHORNEY, Ziqiang LU.
Application Number | 20100295334 12/847407 |
Document ID | / |
Family ID | 40911860 |
Filed Date | 2010-11-25 |
United States Patent
Application |
20100295334 |
Kind Code |
A1 |
CHORNEY; Marc ; et
al. |
November 25, 2010 |
REINFORCED WOOD FLOORING WITH A DISCONTINUOUS GLUE PATTERN FOR
TRUCK TRAILERS AND CONTAINERS
Abstract
Reinforced wood flooring for truck trailers and containers and
methods for making and using the same. A reinforced wood flooring
may include a wood member. The wood member may include a plurality
of wood strips that are attached together. The wood member may also
have a top surface and a bottom surface. An essentially water
impermeable underlay may be attached to the bottom surface of the
wood member with a discontinuous layer of adhesive.
Inventors: |
CHORNEY; Marc; (Hastings,
MN) ; LU; Ziqiang; (Red Wing, MN) |
Correspondence
Address: |
CROMPTON, SEAGER & TUFTE, LLC
1221 NICOLLET AVENUE, SUITE 800
MINNEAPOLIS
MN
55403-2420
US
|
Assignee: |
ROCKLAND FLOORING
Red Wing
MN
|
Family ID: |
40911860 |
Appl. No.: |
12/847407 |
Filed: |
July 30, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12024882 |
Feb 1, 2008 |
7765758 |
|
|
12847407 |
|
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Current U.S.
Class: |
296/184.1 |
Current CPC
Class: |
Y10T 428/183 20150115;
Y10T 428/24994 20150401; B62D 25/2054 20130101; Y10T 428/192
20150115 |
Class at
Publication: |
296/184.1 |
International
Class: |
B62D 25/20 20060101
B62D025/20 |
Claims
1. A reinforced wood floor for truck trailers and containers,
comprising: a floor board having a bottom surface; a layer of
material attached to the bottom surface of the floor board to
reinforce the floor board, the layer of material being attached to
the floor board with a discontinuous layer of adhesive; and wherein
the floor board has opposing end surfaces that are sealed with a
water resistant adhesive.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/024,882, filed Feb. 1, 2008, now U.S. Pat.
No. 7,765,758, the entire disclosures of which is hereby
incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention pertains to reinforced wood flooring.
More particularly, the present invention pertains to reinforced
wood flooring for truck trailers and containers.
BACKGROUND
[0003] Conventional truck trailers may utilize a wood flooring, for
example hardwood flooring, because of the desirable characteristics
that the flooring may provide the trailer. For example, hardwood
flooring may have a desirable level of strength and stiffness. This
may give the flooring a long life and increase its wear resistance.
Of the known wood floorings, each has certain advantages and
disadvantages. There is an ongoing need to provide additional
floorings and methods for making and using floorings.
BRIEF SUMMARY
[0004] The invention provides design, material, manufacturing
method, and use alternatives for reinforced floors for truck
trailers and containers. An example reinforced wood flooring may
include a wood member. The wood member may include a plurality of
wood strips that are attached together. The wood member may also
have a top surface and a bottom surface. An essentially water
impermeable underlay may be attached to the bottom surface of the
wood member with a discontinuous layer of adhesive. The reinforced
floor may be used for truck trailers, containers, etc.
[0005] An example method of manufacturing a reinforced wood
flooring may include providing a wood member. The wood member may
include a plurality of wood strips that are attached together. The
wood member may also have a top surface and a bottom surface. The
method may also include attaching an essentially water impermeable
underlay to the bottom surface of the wood member with a
discontinuous layer of adhesive. The reinforced floor may be used
for truck trailers, containers, etc.
[0006] Another example reinforced wood flooring for truck trailers
and containers may include a wood member. The wood member may
include a plurality of hardwood strips that are attached together.
The wood member may also have a top surface and a bottom surface.
An essentially water impermeable fiber reinforced plastic member
may be attached to the bottom surface of the wood member with a
discontinuous layer of adhesive. The fiber reinforced plastic
member may include a plurality of glass fibers and aramid
fibers.
[0007] The above summary of some embodiments is not intended to
describe each disclosed embodiment or every implementation of the
present invention. The Figures, and Detailed Description, which
follow, more particularly exemplify these embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The invention may be more completely understood in
consideration of the following detailed description of various
embodiments of the invention in connection with the accompanying
drawings, in which:
[0009] FIG. 1 is a plan overview illustrating a reinforced floor
disposed in a truck trailer;
[0010] FIG. 2 is a bottom view of a portion of an example wood
member and an underlay being disposed on the bottom surface of the
wood member;
[0011] FIG. 3 is a side view of a portion of a wood member
illustrating a hook joint;
[0012] FIG. 4 is a perspective view of an example roller;
[0013] FIG. 5 illustrates an example layer of adhesive on a wood
member;
[0014] FIG. 6 illustrates another example layer of adhesive on a
wood member;
[0015] FIG. 7 illustrates another example layer of adhesive on a
wood member;
[0016] FIG. 8 illustrates another example layer of adhesive on a
wood member;
[0017] FIG. 9 illustrates a portion of an example roller for
applying a layer of adhesive on a wood member;
[0018] FIG. 10 illustrates a portion of another example roller for
applying a layer of adhesive on a wood member; and
[0019] FIG. 11 illustrates a portion of another example roller for
applying a layer of adhesive on a wood member.
[0020] While the invention is amenable to various modifications and
alternative forms, specifics thereof have been shown by way of
example in the drawings and will be described in detail. It should
be understood, however, that the intention is not to limit the
invention to the particular embodiments described. On the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the
invention.
DETAILED DESCRIPTION
[0021] For the following defined terms, these definitions shall be
applied, unless a different definition is given in the claims or
elsewhere in this specification.
[0022] All numeric values are herein assumed to be modified by the
term "about," whether or not explicitly indicated. The term "about"
generally refers to a range of numbers that one of skill in the art
would consider equivalent to the recited value (i.e., having the
same function or result). In many instances, the terms "about" may
include numbers that are rounded to the nearest significant
figure.
[0023] The recitation of numerical ranges by endpoints includes all
numbers within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3,
3.80, 4, and 5).
[0024] As used in this specification and the appended claims, the
singular forms "a", "an", and "the" include plural referents unless
the content clearly dictates otherwise. As used in this
specification and the appended claims, the term "or" is generally
employed in its sense including "and/or" unless the content clearly
dictates otherwise.
[0025] The following detailed description should be read with
reference to the drawings in which similar elements in different
drawings are numbered the same. The drawings, which are not
necessarily to scale, depict illustrative embodiments and are not
intended to limit the scope of the invention.
[0026] FIG. 1 is a plan view of an example reinforced wood flooring
10. In this example, flooring 10 is disposed in a truck trailer 12.
Although flooring 10 is illustrated within trailer 12, this is not
intended to limit the invention as flooring 10 may be used, for
example, with a number of different structures including containers
(e.g., shipping and/or freight containers), railroad box cars, and
the like, or any other suitable structure. Trailer 12 may be
structurally similar to typical truck trailers known in the art.
For example, trailer 12 may have a pair of opposing side walls 14
and end doors 16 that can open and close to provide access to the
interior of trailer 12. In at least some embodiments, flooring 10
may extend across the width and along the length of the interior of
trailer 12. Trailer 12 may have a plurality of support members 18
(e.g., "I" beams, "C" beams, hat sections, etc.) that each may have
an upper flange or surface that crosses the width of trailer 12 and
are spaced along the length of trailer 12. In some embodiments,
flooring 10 may be secured to support member 18 by screws (not
shown) or any other suitable fastener, which may penetrate through
the whole thickness of flooring 10 and the upper flange of support
members 18.
[0027] As indicated above, flooring 10 may be a reinforced wood
flooring. By virtue of being reinforced, flooring 10 may be
designed to have a desirable level of strength, stiffness, and the
like. This may be desirable for a number of reasons. For example,
increased strength may allow flooring 10 to be more resistant to
damage and/or wear, carry greater loads (e.g., increase payload),
have a greater life, etc. Furthermore, by virtue of using a
reinforcing structure (e.g., the "reinforcing underlay" such as
underlay 24 described below) in flooring 10, other components of
flooring 10 (e.g., the "wood member" such as wood member 22
described below) may be manufactured to be thinner, which may
decrease the weight of flooring 10 and improve the fuel economy in
trailers using flooring 10. Some additional detail regarding these
and other features can be found below.
[0028] As suggested above, in at least some embodiments, flooring
10 may include one or more floorboards or wood members 22 and a
reinforcing member or underlay 24 disposed along a bottom surface
26 of each wood member 22 as shown in FIGS. 1 and 2. It should be
noted that flooring 10 is illustrated "upside-down" from its use
configuration in FIG. 2 so that some of the features of flooring 10
can be more easily visualized. Accordingly, it can be appreciated
that underlay 24 may be oriented downward when flooring 10 is
installed in trailer 12.
[0029] Wood member 22 may take the form of a floor board of
flooring component that is made from a suitable hardwood such as
oak, maple, ash, birch, beech, aspen, elm, poplar, and the like, or
any other suitable hardwood. Hardwoods may be desirable, for
example, due to their high strength, stiffness, and excellent
durability. Alternatively, some softer woods may also be used,
where appropriate.
[0030] Wood member 22 may include a plurality of wood strips 28
that are fastened together. For example, wood strips 28 are
arranged in a side-to-side and end-to-end manner in order to form
wood member 22. To manufacture the individual strips 28, green
(i.e., not dried) wood logs may be cut into lumber using
conventional techniques. The lumber may be kiln-dried so that it
has an equivalent moisture content of about 6 to 10%.
Alternatively, the lumber may be seasoned or otherwise allowed to
dry to the desired moisture content. The dried lumber may be sanded
and planed into the desired thickness. For example, the lumber may
be sanded and planed so that it has a thickness of about 0.75 to
1.5 inches, or about 1 to 1.25 inches thick. The lumber may also be
cut into the desired width, for example, using a ripsaw. For
example, the lumber may be cut to have a width of about 0.75 to 2
inches, or about 1 to 1.4375 (i.e., 1- 7/16) inches wide.
[0031] During the manufacturing of strips 28, any wood defects such
as knots, cracks and fractures, bark pockets, cavities and holes by
insects, decay by fungi, and stains by molds may be removed by
cutting off the defects with, for example, a chop saw or suitable
automatic cutting system. It can be appreciated that such cutting
may alter the length of strips 28. It may be desirable for minimum
length of wood strips 28 to be about 12 inches in wood member 22.
Overall, the average length of wood strips 28 may be between about
three and three and one-half feet.
[0032] Both of the opposing ends of each wood strip 28 may be cut
into a square shape with, for example, a tennoner saw. The squared
ends of wood strips 28 may also be further cut so that "hooks" are
formed therein. These hooks allow wood strips 28 to be attached
end-to-end by mating adjacent hooks and forming a "hook joint" 30
as illustrated in FIG. 3. The depth or size of hook joint 30 may
vary depending on the application. For example, the depth of hook
joints 30 may be about 0.25 to 0.75 inches, or about 0.25 to 0.5
inches, or about 0.375 inches. Alternatively, any other suitable
type of joint may be utilized to join together wood strips 28.
[0033] The suitably prepared wood strips 28 may also be fastened
together side-to-side using any suitable attachment technique. For
example, the vertical sides or edges of each wood strip 28 may be
coated with an adhesive by a roller glue spreader. This may help to
secure wood strips 28 across the width of wood member 22. A
suitable adhesive for this securing may include urea-melamine
formaldehyde, crosslinking polyvinyl acetate, isocyanate, and the
like. The glue-coated wood strips 28 may be assembled (e.g., both
side-to-side and end-to-end) on a conveyor. This may include manual
assembly. The hook joints 30 may fasten together the adjacent ends
of strips 28 to form a continuous slab, in which they are jointed
end-to-end in a number of rows (as illustrated in FIG. 1). It may
be desirable to control the number of hook joints 30 per square
foot. For example, it may be desirable to have about 5 to 7 hook
joints 30 per square foot on average. The joined collection of wood
strips 28 may be placed into a steam or radio frequency hot press
under vertical and cross-direction pressures for curing of the
adhesive.
[0034] Once strips 28 are secured together in the desired fashion,
the resultant board may be cut to the desired length. For example,
the board may be cut to a length of about 56 feet (or more or less
depending on the application). Additionally, the board may also be
divided into a number of floorboards or wood members 22 that each
have a width, for example, of about 10 to 14 inches or about 12
inches to 12.25 inches. These wood members 22 may be planed (and/or
sanded) to a desired thickness. For example, wood member 22 may be
planed to a thickness of about 1 to 1.5 inches, or about 1.125
inches, or about 1.3125 inches, or about 1.375 inches, etc.
[0035] Trailers like trailer 12 may include a plurality of wood
members 22 joined together to form flooring 10. For example,
trailer 12 may include about 6 to 10 wood members 22, or about 8
wood members 22, or more or less depending on the application. To
facilitate the joining of wood members 22, shiplaps 32 and crusher
beads 34, which may be similar to those known in the art, may be
machined on to both edges of each wood member 22. Shiplaps 32 may
be convenient for installing floorboards on truck trailers by
allowing adjacent wood member 22 to overlap. Crusher beads 34 may
provide spaces between adjacent wood members 22, which may protect
members 22 from buckling due to their expansion in wet
conditions.
[0036] In some embodiments, bottom surface 26 of wood members 22
may be coated with a water resistant polymeric layer (e.g., latex).
However, this may not be necessary when underlay 24 is utilized.
Wood members 22 may be sealed at both ends with a water resistant
adhesives. To avoid the water or moisture penetration from both
ends of reinforced wood flooring 10, a water resistant adhesive
resin such as epoxy and crosslinking polyvinyl acetate may also be
used at the ends of wood members 22. The top surface of wood
members 22 may be optionally coated with a suitable epoxy, lacquer,
or varnish to improve the durability and water resistance of wood
members 22 during installation and maintenance.
[0037] As indicated above, wood members 22 may include underlay 24
along bottom surface 26. Underlay 24 may be an essentially water
impermeable underlay 24. More particularly, underlay 24 may
essentially prevent water (including liquid water and/or water
vapor) from passing therethrough. Accordingly, using a water
impermeable underlay 24 may be desirable because it may form a
water barrier at the bottom of flooring 10, where flooring 10 would
otherwise be exposed to the outside environment.
[0038] In addition, underlay 24 may include a structure that may
add desired strength to wood member 22. This may be desirable for a
number of reasons. For example, adding strength may improve wear
resistance, extend life, increase the payload of a trailer (e.g.,
trailer 12), etc. In at least some embodiments, underlay 24
includes a fiber reinforced plastic (FRP). An FRP, as known for
conventional FRPs, may include a plurality of continuous
reinforcing fibers that are impregnated with or otherwise include a
polymeric resin or matrix. The continuous fibers may be carbon
fibers, glass fibers, aramid fibers (e.g., Kevlar.RTM. by DuPont
& Co.), and the like, or mixtures and/or combinations thereof
The fibers may make up about 50-90%, or about 60-80%, or about 70%
of the weight of underlay 24.
[0039] In at least some embodiments, an example underlay 24 may
include a combination of glass fibers and aramid fibers. These
fibers may be divided so that the ratio of glass fibers to aramid
fibers, by weight, may be about 8:1 to 10:1, or about 9:1. For
example, an example underlay 24 may include about 60-65% (e.g.,
about 63%) glass fibers and about 5-10% (e.g., about 7%) aramid
fibers. Of course, other ratios and/or fibers may also be
utilized.
[0040] The polymeric resin or matrix may include a thermosetting
adhesive such as polyester, vinyl ester, polyurethane, phenol
formaldehyde, epoxy, phenolic, or the like. Optionally, the FRP
also may include a thermoplastic resin such as polyethylene,
polypropylene, polyvinyl chloride, polyamide (e.g., polyamide 6 and
polyamide 6/6), polyethylene terephthalate, and the like, or any
other suitable material. The FRP may be manufactured according to
conventional manufacturing processes such as pultrusion, as known
in the art.
[0041] The arrangement of the fibers in underlay 24 may also vary.
In some embodiments, all of the fibers in underlay 24 may be
oriented in the same direction. For example, underlay 24 may
include fibersthat are all oriented in the longitudinal direction
(i.e., along the length of trailer 12). In some other embodiments,
most of the fibers may be oriented in the longitudinal direction.
Alternatively, some of the fibers in underlay 24 may be oriented in
one direction and some of the fibers may be disposed in a different
direction such as, for example, perpendicularly to those fibers.
For example, underlay 24 may include about 70% or more of the
fibers oriented in the longitudinal direction and the balance of
them arranged perpendicular to those fibers, or about 80% or more
of the fibers oriented in the longitudinal direction and the
balance of them arranged perpendicular to those fibers, or about
90% or more of the fibers oriented in the longitudinal direction
and the balance of them arranged perpendicular to those fibers.
[0042] Underlay 24 may also vary in thickness. In some embodiments,
underlay may be about 0.025 to about 0.050 inches thick, or about
0.030 to about 0.040 thick, or about 0.033 inches thick. Underlays
24 of these thicknesses may provide a suitable degree of
reinforcement while being sufficiently thin so as to reduce the
overall weight of flooring 10. This may desirably impact the
properties of flooring 10 by allowing for trailers such as trailer
12 to consume less fuel when transporting goods (i.e., less fuel
consumption with the same payload) or the ability to carry more
goods (i.e. increased payload). Furthermore, FRP underlays 24 may
reinforce wood member 22 sufficiently so that wood members 22 may
be further thinned, which also may desirably reduce the weight of
flooring 10.
[0043] Underlay 24 may be attached to wood member 22 using a
suitable adhesive or adhesive layer (such as adhesive layer 48,
which is illustrated cut away in FIG. 2). For example, adhesive
layer 48 may include a hot melt reactive polyurethane resin (e.g.,
PUR polyurethane resin) or any other suitable adhesive. It should
be noted that the following discussion describes the use of PUR in
flooring 10 but this is not intended to limit the invention as
essentially any other suitable adhesive may be used for adhesive
layer 48 without departing from the spirit of the invention.
[0044] The PUR adhesive may be placed on a reservoir adjacent a
pair of heated rollers, including, for example, roller 36. The
temperature of rollers may be controlled to be between 260 and
280.degree. F., which may melt the PUR material. Alternatively,
molten PUR may be applied directly to roller 36. After the PUR
resin is completely melted, wood members 22 may pass through a gap
between the rollers and wood members 22 are coated with the PUR
material. Underlay 24 may be quickly laid onto the glueline (i.e.,
the layer of PUR material disposed on wood members 22) and pass
through a pair of cold rollers (also called pinch rollers) under
pressure. The pressure of the pinch rollers may be adjusted to
achieve a desirable bonding strength as well as the desired
distribution of adhesive (e.g., avoiding and/or limiting "pinch
out" of adhesive). The resultant reinforced wood flooring 10 is
stored at room temperature for 24 hours to complete further
solidification and/or curing of the PUR. The FRP edges of the cured
reinforced wood flooring 10 may be trimmed with a suitable cutting
tool to remove any excess material. This may form the reinforced
wood flooring 10 (and/or one of the floor boards making up flooring
10).
[0045] Hot melt reactive polyurethanes like PUR may be desirable
for a number of reasons. For example, hot melt reactive
polyurethanes may provide excellent bonding between wood (e.g.,
wood members 22) and FRP plies (e.g., underlays 24). However, the
holt melt reactive polyurethanes are relatively expensive. In
addition, completely and/or continuously coating wood member 22
with the PUR material may add weight to flooring 10. Because of
these factors, it may be desirable to reduce the amount of PUR
utilized in flooring, for example, to reduce manufacturing costs
and/or weight of flooring 10.
[0046] In at least some embodiments, adhesive layer 48 is a
discontinuous layer of adhesive and/or a discontinuous glue pattern
may be utilized to reduce the amount of PUR used. For example,
adhesive layer 48 may include an adhesive portion or portions 49
and an adhesive lacking portion or portions 50. It should be noted
that adhesive lacking portions 50 are illustrated as darkened
strips in the figures. This is done so that these portions 50 can
be more easily visualized. For the purpose of this invention, a
discontinuous layer of adhesive and/or a discontinuous glue pattern
(which may also be termed a "glueline" in the art) may be
understood to be layer of adhesive or a glue pattern that is
designed to cover less than all of the surface area of bottom
surface 26 of wood members 22. For example, discontinuous layer of
adhesive 48 may cover less than 100% of the surface area of bottom
surface 26 of wood members 22, or about 98% or less of the surface
area of bottom surface 26 of wood members 22, or about 96% or less
of the surface area of bottom surface 26 of wood members 22, or
about 95% or less of the surface area of bottom surface 26 of wood
members 22, or about 90% or less of the surface area of bottom
surface 26 of wood members 22. These discontinuous layers of
adhesive 48 differ from a continuous layer of adhesive (and/or
continuous glueline), which is designed to cover essentially 100%
of the surface area of a wood member surface.
[0047] Forming discontinuous layer of adhesive 48 may include the
use of a coating roller with a varying format to apply the adhesive
to wood member 22. For example, a coating roller 38 for applying
discontinuous layer of adhesive 48 on bottom surface 26 of wood
member 22 is illustrated in FIG. 4. Roller 38 may include one or
more grooves or recesses 40, a base or rubber layer 42, a drum 44,
and axis shaft 46. It can be appreciated that grooves 40 are
arranged substantially parallel to one another in roller 38. Other
rollers are contemplated where grooves 40 may intersect.
[0048] Base layer 42 may be the adhesive applying portion of roller
38. The material for base layer 42 may be selected based on a good
balance of elasticity and stiffness. For example, base layer 42 may
include a natural or a synthetic rubber such as silicone, neoprene,
styrene butadiene rubber, EPDM rubber, fluoro-silicone,
polyisoprene, nitrile, polyurethane, viton, or the like. It may
also be convenient to select these materials because they may be
easy to be cut them into certain shapes by machine in order to form
a variety of different coating patterns and/or coating designs.
Grooves 40 may be formed by cutting away or removing a portion of
the base layer 42. By doing so, grooves 40 are designed so that
they essentially will not apply adhesive to wood member 22.
Additionally, a suitable "groove cleaning" structure or assembly
(e.g., another roller with projections designed to "mate" with
grooves 40) may be utilized that can clean out or otherwise remove
adhesive that may become disposed in grooves 40.
[0049] In use, adhesive may be applied to roller 38, for example,
by heating roller 38 and rolling it through the adhesive (e.g.,
PUR). In doing so, adhesive may be applied to base layer 42 (i.e.,
the adhesive applying portion of roller 38) but not grooves 40.
Wood member 22 may then be fed through roller 38 (e.g., with the
rotation of roller 38 being the same as the feeding direction of
wood member 22). When roller 38 contacts wood member 22, base layer
transfers adhesive to wood member 22 (e.g., at adhesive portion 49)
whereas grooves 40 essentially do not transfer adhesive to wood
member 22 and, instead, leave or form portions 50, which lack
adhesive as shown in FIG. 5. This pattern defines discontinuous
layer of adhesive 48 along bottom surface 26 of wood member 22.
[0050] It can be appreciated that roller 38, by virtue of having
grooves 40 arranged parallel to one another, forms adhesive-lacking
portions 50 that are arranged as two parallel strips extending
longitudinally along wood member 22. This arrangement, however, is
not intended to be limiting. Indeed, base layer 42 can be cut into
essentially any desired shape to form a discontinuous layer of
adhesive having a different pattern. FIGS. 6-8 illustrate some of
the example patterns that are contemplated. For example, FIG. 6
illustrates a discontinuous layer of adhesive 148 where
adhesive-lacking portions 150a/150b are arranged as strips with
broken or interrupted regions 152a/152b that include adhesive
and/or are part of adhesive layer 148. FIG. 7 illustrates a
discontinuous layer of adhesive 248 that includes three parallel
adhesive-lacking strips 250a/250b/250c that are broken by regions
252 that include adhesive 48 and/or are part of adhesive layer 248.
The length L may be equal to the perimeter of the coating roller
used to form layer 248. Accordingly, the alternating strips
250a/250b/250c have a length that is equal to about half the
perimeter of the roller. This may help better distribute the local
stress on the discontinuous layer of adhesive 248 and thus
effectively reduce the stress concentration along the discontinuous
layer of adhesive. FIG. 8 illustrates a discontinuous layer of
adhesive 348 that includes four parallel adhesive-lacking strips
350a/350b/350c/350d that are broken by regions 352 that include
adhesive and/or are part of adhesive layer 348. The patterns
illustrated in FIGS. 6-8 illustrate that essentially any suitable
number of adhesive-lacking portions may be utilized and that these
portions may or may not be broken or interrupted.
[0051] FIGS. 9-11 illustrate portions of example rollers that may
be utilized to form additional discontinuous layers of adhesive.
For example, FIG. 9 illustrates a portion of roller 438 that
includes base 442 and three grooves 440a/440b/440c that are
intersected by three more grooves 440d/440e/440f. Similarly, FIG.
10 illustrates a portion of roller 538 that includes base 542 and a
plurality of intersecting diagonal grooves
540a/540b/540c/540d/540e/540f. This may form a discontinuous layer
of adhesive that takes the form of a web or web-like configuration.
The patterns illustrated in FIGS. 9-10 illustrates that
intersecting configurations having essentially any suitable number
of grooves may be utilized for forming discontinuous layers of
adhesives.
[0052] Finally, FIG. 11 illustrates a portion of an example roller
638 that includes base 642 and a plurality of grooves
640a/640b/640c having a complex geometry intersected by grooves
640d/640e/640f. In the embodiment shown in FIG. 11, grooves
640a/640b/640c/640d/640e/640f are arranged so that base 642 has a
shape resembling a pair of hexagons adjoined hexagons. Designs like
the one shown in FIG. 11 may help evenly distribute the stress of
adhesive on reinforced wood flooring 10 and effectively reduce the
amount of adhesive applied to wood members 22. This figure
illustrates that the adhesive-lacking strips of a discontinuous
layer of adhesive need not take the form of lines and that
essentially any suitable shape pattern may be utilized without
departing from the spirit of the invention.
[0053] When applying adhesive 48 in any of the patterns disclosed
above, it may be desirable to keep any of the adhesive-lacking
strips away from the lateral edge of wood member 22. For example,
it may be desirable for any of the adhesive-lacking portions or
strips to be at least one inch away from the edges wood member 22.
This may help to reduce and/or avoid contact of moisture or water
with wood member 22.
[0054] To avoid the water or moisture penetration from both ends of
reinforced wood flooring 10 into the discontinuous layer of
adhesive, certain water resistant adhesive resins such as epoxy and
crosslinking polyvinyl acetate may be used. The surface sealing by
these adhesives may improve performance and durability of
reinforced wood flooring 10 with a discontinuous layer of
adhesive.
EXAMPLES
[0055] The invention may be further clarified by reference to the
following Examples, which serve to exemplify some of the preferred
embodiments, and not to limit the invention in any way.
Example 1
[0056] A fiberglass reinforced polyurethane ply having a nominal
thickness of 0.033 inches was used for underlay 24. The resin
included about 30% by weight polyurethane. In this example, the FRP
underlay 24 included approximately 7% by weight of aramid fibers
and about 63% by weight of glass fibers. Use of aramid fiber may
significantly improve mechanical performance of the FRP underlay 24
and allow it to have a reduced thickness. At least 90% of the
reinforcing fibers were arranged so that they lined up
longitudinally along wood member 22.
[0057] A hot melt reactive PUR resin was used for the adhesive 48
for bonding the FRP underlay 24 to wood member 22. The melting
temperature of PUR is about 260.degree. F.
[0058] Laminated wood members 22 were used to manufacture an
example reinforced wood flooring 10. The nominal thickness of wood
members 22 was about 1.0625 (1- 1/16) inches. The target thickness
of reinforced wood flooring 10 was about 1.125 inches.
[0059] Wood members 22 were manufactured according to the
aforementioned procedures. An example wood member 22 was coated
with hot melt reactive PUR through the roller coater 38. This
resulted in a discontinuous layer of adhesive where adhesive 48 was
applied to portions of wood member 22 and two continuous, parallel
adhesive-lacking strips 50 were formed as illustrated in FIG. 5. In
this example, the adhesive layer 48 was about 0.020 inches in
thickness.
[0060] An FRP underlay 24 was then disposed on adhesive-coated wood
member 22 and the structure was passed through a pair of pinch
rollers while applying pressure. The resultant reinforced wood
floorboards 10 were stored at room temperature and at a relative
humility of 50% for 72 hours prior to mechanical testing.
Example 2
[0061] Flexural and dry shear properties of reinforced wood
flooring 10 formed in Example 1 were tested in accordance with ASTM
standard ASTM D198. For the flexural test, a three point bending
mode was applied. The flexural span was 30 inches. The testing
speed was 0.48 inch/min.
[0062] In addition, a wet shear test was conducted for reinforced
wood flooring 10. The wet shear test follows a soaking-drying
procedure by an industrial standard. The flooring 10 samples were
submerged 2 inches down from the water level and soaked in tap
water for 48 hours. They were then placed in an oven at 140.degree.
F. and dried for 16 hours. After that, they were removed from the
oven and soaked again for another 8 hours. Finally, flooring 10
samples were removed from water and allowed to dry for 2 hour
before shear testing. These procedures were also performed on
control flooring samples including a sample laminated wood
floorboard lacking underlay 24 (hereafter Control 1) and a sample
flooring with a continuous layer of adhesive (hereafter Control
2).
[0063] The results of the mechanical testing are listed in Table
1.
TABLE-US-00001 TABLE 1 Mechanical performance of discontinuous
layer of adhesive. Thick- Max. Flexural Flexural Maximum Test ness
flexural strength modulus shear load (lbs) sample (inch) load (lbs)
(psi) (psi) Dry Wet Control 1.sup.1 11/8 3,850 11,027 1,600,000
1,850 800 Control 2.sup.2 11/8 7,102 21,220 2,006,272 5,437 3,455
Flooring 11/8 6,771 20,229 1,935,184 4,675 3,360 10.sup.3
.sup.1Laminated oak floorboards, values of mechanical properties
are the baseline required by the industry standard.
.sup.2Reinforced oak floorboards with continuous layer of adhesive.
.sup.3Reinforced oak floorboards with a discontinuous layer of
adhesive.
[0064] As shown in Table 1, the reinforced wood floorboards (e.g.,
Control 2 and flooring 10) are much stronger and stiffer than
laminated wood floorboards (Control 1). At the same nominal
thickness, the discontinuous layer of adhesive in flooring 10
decreases by only about 5% and 16% in flexural and dry shear
strengths, respectively. However, both have the same performance in
wet shear. These results unexpectedly indicate that a significant
savings in material and manufacturing costs can be achieved using a
discontinuous layer of adhesive without compromising strength and
performance of flooring 10.
[0065] It should be understood that this disclosure is, in many
respects, only illustrative. Changes may be made in details,
particularly in matters of shape, size, and arrangement of steps
without exceeding the scope of the invention. The invention's scope
is, of course, defined in the language in which the appended claims
are expressed.
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