Note: Descriptions are shown in the official language in which they were submitted.
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SURFACE ADHESIVES FOR BUILDING BOARDS
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Application Ser. No.
61/926,524, filed
Jan. 13, 2014, and entitled "Surface Adhesives for Building Boards," the
contents of
which are fully incorporated herein for all purposes.
TECHNICAL FIELD
[0002] This disclosure relates to surface adhesives for building boards. More
particularly, this disclosure relates to building boards with an applied
pressure sensitive
adhesive.
BACKGROUND OF THE INVENTION
[0003] Building board, also known as wallboard, plasterboard, or drywall, is
one of the
most commonly used building components in the world today. Building board is
frequently used within the interior or exterior of dwellings. One particularly
popular form
of building board is known as gypsum board. Gypsum board is constructed by
depositing a layer of cementitious gypsum slurry between two opposing paper
liners.
Gypsum boards generally have a smooth external surface, a consistent
thickness, and
allow for the application of finishing enhancements, such as paint. One
drawback of
existing gypsum building boards is that it is often difficult to secure
fasteners into the
surface of the board. This complicates the task of hanging objects, such as
pictures or
shelving. It also poses problems for mounting the board on framing members.
Gypsum
board can also be used as a backing for tiles. Tile backing board is often
used in high
humidity environments such as bathrooms and pool areas. It is important for
tile
backing board to provide a firm hold on the tiles and at the same time be
resistant to
moisture.
[0004] One useful development is known as glass reinforced gypsum (GRG) board.
An example of one such board is disclosed in U.S. Pat. No. 4,265,979 to Baehr
et. al.
Baehr discloses a paper-free gypsum board construction. A subsequent
improvement
is described in commonly owned U.S. Pat. No. 4,378,452 to Pilgrim. Pilgrim
discloses a
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GRG board that is faced on one or both sides with a porous, nonwoven glass
mat. The
glass mat of Pilgrim is slightly embedded into the slurry core.
[0005] A further embodiment was realized by embedding the mat within the core.
The creates a thin film of slurry on the outer surface of the board. Building
boards with
this construction are referred to as embedded glass reinforced gypsum (EGRG)
boards.
EGRG boards eliminate, or greatly reduce, the presence of exposed fibers and
otherwise provide a smooth working surface.
[0006] Thus, there exists a need in the art to provide building boards that
can be
easily and firmly secured to associated framing members. There also exists a
need in
the art for building boards that can easily and firmly hold finishing
materials. The
present disclosure fulfills these and other needs in the art by providing a
pressure
sensitive adhesive layer on the interior or exterior surface of a building
board.
SUMMARY OF THE INVENTION
[0007] One of the advantages of this invention is realized by providing
building
boards that can be easily and firmly attached to associated framing members.
[0008] Another advantage is attained by including a polymer-based adhesive on
the
surface of the board that eliminates the need for external fasteners.
[0009] Yet another advantage is attained by applying a performance enhancing
layer
to the surface of a building board.
[0010] A further advantage is achieved by providing a polymer-based adhesive
over
top of a building board.
[0011] An additional advantage is realized by applying a polymer-based
adhesive to
the polymer modified dense slurry layer of a building board, thereby
permitting the
adhesive to bond to the slurry layer.
[0012] Various embodiments of the invention may have none, some, or all of
these
advantages. Other technical advantages of the present invention will be
readily
apparent to one skilled in the art.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0013] For a more complete understanding of the present disclosure and its
advantages, reference is now made to the following descriptions, taken in
conjunction
with the accompanying drawings, in which:
[0014] FIG. 1 is a perspective view of a building board in accordance with the
present
disclosure.
[0015] FIG. 2 is a elevational view of a roller coater for use in applying
the polymer-
based adhesive of the present disclosure.
[0016] FIG. 3 is a cross sectional view taken along Line 2-2 of FIG. 1.
[0017] Similar reference characters refer to similar components throughout the
several views of the drawings.
DETAILED DESCRIPTION OF THE DRAWINGS
[0018] The present disclosure relates to coatings for building boards. In
particular, the
disclosure relates to pressure sensitive adhesives ("PSA"). These PSA coatings
can be
any of a variety of polymer based adhesives that are bonded to the surface of
the
board. The disclosed PSAs eliminate the need for fasteners, which are
otherwise
required to hang objects upon the board or hold boards in place after
installation. The
various components of the present invention, and the manner in which they
interrelate,
are described in greater detail hereinafter.
[0019] The PSAs 10 are thermoplastic based surface adhesives within an inner
and
an outer surface. The inner surface is adapted to adhere to an exterior
surface of an
underlying building board 20. PSA 10 is preferably applied to the board via a
roller
coater 40. In the preferred embodiment, the interior surface of PSA 10 is
adhered to a
polymer modified dense gypsum slurry layer (PMDSL) 30 that is formed at the
exterior
surface of board 20. The PSA may include reactive and/or nonreactive
components
that chemically bond with one or more polymers in PMDSL 30. When the PSA 10 is
applied to the exterior surface of a building board 20, the outer surface of
PSA 10
functions as a binding adhesive for applied finishing materials. This
eliminates the need
for secondarily applied adhesive mechanisms to hold or affix the finishing
materials. In
particular, PSA 10 can be used to adhere decorative tiles to a gypsum
wallboard (i.e.
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tile backing board). The inner surface of PSA 10 is secured to the exterior
surface of
the tile backing board. The outer surface of the PSA 10 would then be used to
firmly
secure associated tiles. A release liner may optionally be used to cover the
outer
surface of PSA 10 until the tiles are adhered.
[0020] Alternatively, PSA 10 can be secured to the back, or interior surface,
of a
building board 20. When applied in this manner, PSA 10 can be used to secure
the
building board to studs or framing members. This eliminates the use of
traditional
fasteners like screws or nails. It is also within the scope of the present
disclosure to
apply a PSA 10 to both the interior and exterior faces of board 20.
Roller Coater Applied PSAs.
[0021] The PSAs disclosed herein can be directly applied to the surface of the
underlying building board via one or more heated roller coaters. This allows
the PSAs
to be directly applied to the polymer modified dense gypsum slurry layer
(PMSDL) in the
underlying board. The roller coaters can be forward or rearward driven and may
be
heated. The rollers are used in applying a strong or weak chemical bond to the
polymeric compound within the PMDSL. The application and metering roller are
heated,
and the application roll hardness is engineered to create the proper
uniformity of the
PSA coating applied to the topography of the PMDSL. The heated roller coater
can coat
either face of the building board singularly or simultaneously. The rollers
can also apply
the PSA in varied application volumes.
[0022] The pressure of the application roller is capable of applying varying
pressures
against the PMDSL to control the interrupted or continuous application of the
PSA. The
temperature of the rollers is selected based upon the rheology of the
polymeric
compound and is chosen to provide an engineered continuity of the PSA being
applied.
The gap between the application roller and the metering roller is varied to
control the
application rate of the PSA. The application rate can be varied depending upon
the
inherent heat, the particular rheology of the PSA, and/or the effect of
desired operating
temperature.
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Reactive and Nonreactive PSAs.
[0023] The PSAs described herein are preferably applied after being heated to
a
liquefied stated. They can consist of reactive and/or nonreactive polymeric
compounds.
The nonreactive polymeric compounds within the PSA are fully polymerized
polymeric
compounds that are taken through a phase change to the liquid state thus
allowing their
application to the PMDSL. The basic structure of the original polymer (or
polymers) are
maintained, however, crosslinking and other aforementioned chemical bonding
will
occur.
[0024] When the PSAs include reactive components, they form a polymer matrix
within the underlying PMDSL. More specifically, the reactive components within
the
PSA form a polymer matrix extension with polymer chains within the PMDSL. The
reactive polymeric compounds within the PSA initiate as monomers and are then
heated to improve kinetics. The reactive compounds subsequently polymerize
upon
application to the PMDSL. This polymerization is a result of their inherent
properties.
[0025] The PSAs described herein can consist of one or more of the following
thermoplastic materials, used singularly or in combination with one another:
Acrylonitrile butadiene styrene (ABS), Celluloid, Cellulose Acetate, Ethylene-
Butyl
Acrylate, Ethylene-Methyl Acrylate, Ethylene Vinyl Acetate (EVA), Ethylene
Vinyl
Alcohol (EVAL), Fluoroplastics (PTFEs, including FEP, PFA, CTFE, ECTFE, ETFE),
lonomers, Liquid Crystal Polymer (LCP), Polyacetal (POM or Acetal),
Polyacrylates
(Melt and Cure Acrylics), Polyacrylonitrile (PAN or Acrylonitrile), Polyamide
(PA or
Nylon), Polyamide-imide (PAI), Polyaryletherketone (PAEK or Ketone),
Polybutyadiene
(PBD), Polybutylene (PB), Polybutylene Terephthalate (PBT), Polybutylene
Terephthalate (PET), Polycyclohexylene Dimethylene Terephthalate (PCT),
Polycarbonate (PC), Polyketone (PK), Polyester,
Polyethylene/Polythene/Polyethane,
Polyether Block Amide (PEBA), Polyetheretherketone (PEEK), Polyetherimide
(PEI),
Polyethersulfone (PES), Polyethylenechlorinates (PEC), Polyimide (P1),
Polylactic Acid
(PLA), Polymethylpentene (PMP), Polyphenylene Oxide (PPO), Polyphenylene
Sulfide
(PPS), Polyphthalamide (PPA), Polypropylene (PP), Polystyrene (PS),
Polysulfone
(PSU), Polyvinyl Chloride (PVC), SpectraIon, thermoplastic Olefinic Elastomer
(TPO).
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[0026] The preferred water vapor permeability of the applied PSA coating may
range
from a minimum of .01 to a maximum of 98, thus the coating may be virtually
impervious
to the transmission of water vapor movement or completely open to the
transmission of
water vapor movement. Thermoplastic PSA translucence may range from .001 (:)/0
to
100 (:)/0 translucence.
[0027] The underlying thermoplastic coating and or the thermoplastic PSA
coating
may contain filler compounds which are intended for uses which may include but
are not
limited to color (opaque or translucent), UV resistance, tachifying property
enhancement, thermal insulation, thermal conductivity, electrically
conductivity,
electrically non-conductivity, water resistance, water vapor transmission
enhancement,
water vapor transmission inhibition, light absorption, light refraction, sound
propagation,
sound inhibition, elastomeric enhancement, rigidity enhancement, impact
resistance,
puncture resistance, abrasion resistance, volumizing, densifying, fire
resistance, and
sound reverberation.
[0028] The PSA coating upon application may be engineered to offer desired
surface
topography that may range from smooth profile (having surface variations of
.01 mils or
less) to a coarse profile equivalent to a desired specification. The applied
film
thicknesses of the above mentioned PSA may range from a minimum of .01 mils to
and
maximum of 500 mils in thickness. The applied film thickness may be applied in
one or
multiple applications at varying or equivalent application temperatures and
varying or
equivalent application speeds. The melt point temperature of the PSA may range
from
a minimum of 100 degrees Fahrenheit to a maximum of 500 degrees Fahrenheit.
The
PSA coating may be applied immediately following the initial set of the gypsum
substrate or anytime thereafter. The application of the PSA coating to the
underlying
substrate may be accomplished by any of the following: gravity fed, pump fed,
forward
or reverse roll coaters, or pump fed hot melt curtain coater. It is also
within the scope of
the invention to apply the PSA via hot melt spray systems, such as high
pressure, low
volume or low pressure, high volume methods. The PSA coating may be applied to
any
or all surfaces of the board. The PSA coating may be applied by means of
continuous
or non-continuous process methods. However, continuous coating methods are
preferred.
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Mechanics of the Coating Attachment
[0029] Dependent upon rheology, temperature, roller hardness, and coating
volume
the PSA may be applied to the upper or lower (face or back) topography of the
building
board. In one possible embodiment, the PSA can be applied so as to mirror the
substrate topography. This mirroring of the topography provides mechanical
bonding
whereby the PSA coating attaches itself to the surface of the PMDSL via simply
adhesive properties, by flowing into and throughout the open topographic areas
of the
PMDSL surface. This provides an adhesion and mechanical interlocking that is
in reality
a greater contact surface area than visibly evident.
[0030] Due to the polymer contained in the PMDSL, a myriad of chemical bonding
opportunities are available. Correct selection of the polymeric compounds
allow the
application of Vanderwal, ionic, and valent & covalent bonds, and crosslinking
bonds
between the PMDSL polymer and the heat applied PSA. The PSA can be applied as
a
single layer or as a multilayer laminate. In the preferred embodiment, the PSA
is
applied to the PSMDL layer. Alternatively, the PSA can be applied to the glass
face or
cementitious pre-coated glass mat (also known as GRG board). The PSA can also
be
applied to paper faced gypsum building panels. It can likewise be applied to
any of a
variety of cementitious, hydraulic cement, magnesium based, or composite based
building panels. Composite based building panels may include, for example,
gypsum
fiber boards. It can further be applied to any building panel intended for
interior or
exterior lining surfaces. Although these boards may include a PMDSL, it is
within the
scope of the present invention to apply the PSA directly to a glass faced or
paper faced
board.
[0031] Utilizing the aforementioned bonding, mechanical, and chemical adhesion
properties single or multi PSA laminations may be incorporated into the
resulting
composite building panel. These PSA laminates may be engineered for a variety
of
different physical properties and may provide one or more of the follow
characteristics:
= Engineered strength
= Electrically generated radiant heat
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= Flexibility/impact/abuse/abrasion/sound/thermal/water/mold and
mildew resistance enhancements
[0032] In use, the PSA is applied to the underlying board as noted above. The
PSA
can be applied to treated or untreated surfaces. It may likewise be adhered to
prepared
or partially prepared building panels. Thereafter, to aid in storage and
transport, the
PSA is covered with a specially treated release sheet. The release sheet
prevents the
PSA from adhering to other panels or objects when placed in stacks for
warehousing or
sale.
Fillers and Modifiers
[0033] The PSAs described herein may include one or more fillers or modifiers
to
increase the physical properties of the resulting building boards. Both
reactive and
nonreactive polymeric compounds provide the ability to suspend and encapsulate
performance enhancing filler and or modifier. These fillers and modifiers may
provide
one or more of the following enhancements:
= Electrical conductivity
= EMF resistance
= Lower polymeric densities
= Sound attenuation
= Water resistance
= Intumescent and or fire resistant enhancers
= Heat transfer resistance
= Elastomeric performance enhancers
[0034] The PSA may be applied to the face and or back of building panels and
functions as a binding adhesive for applied finishing materials. This
eliminates the need
for secondarily applied adhesive mechanisms to hold or affix the finishing
materials.
When applied to the back of a building panel, the PSA eliminates the use of
traditional
fasteners like screws, nails and or both.
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[0035] When used as a mechanism applied to the back stud installation side of
the
building panel, the PSA offers an improved affixing, holding, and securing
characteristics. This improvement is realized with both organic and or
inorganic
structural studs and or framing members. The PSA can improve pounds force
resistance by between .01 times to 100 times than that achieved with
traditional
fasteners like nails and or screw.
[0036] Although this disclosure has been described in terms of certain
embodiments
and generally associated methods, alterations and permutations of these
embodiments
and methods will be apparent to those skilled in the art. Accordingly, the
above
description of example embodiments does not define or constrain this
disclosure. Other
changes, substitutions, and alterations are also possible without departing
from the
spirit and scope of this disclosure.
