Note: Descriptions are shown in the official language in which they were submitted.
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COMPOSITE BUILDING BOARDS WITH THERMOPLASTIC
COATINGS AND CEMENTITIOUS PRECOATED FIBROUS MATS
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] This invention relates to an improved construction for
composite building boards. More particularly, the present invention
relates to a composite building board with an external hot melt
thermoplastic coating applied over a cementitious pre-coated fibrous
mat.
Description of the Background Art
[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 of a
dwelling, where it functions both as a finished wall covering and as a
structural room partition. Building board can also be used on the
exterior of a dwelling, where it serves as a sheathing to provide
weather protection and insulation. Building board can also be used as
an interior facing for other structures as well, such as stairwells,
elevator shafts, and interior ducting.
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[0004] 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 slurry is the semi-hydrous form of calcium sulfate and has
many physical characteristics that make it suitable for use as a building
component. For example, gypsum boards generally have a smooth
paper surface, a consistent thickness, and allow for the application of
finishing enhancements, such as paint. Gypsum board is also
desirable because it provides a degree of fire resistance and sound
abatement.
[0005] An example of a paper-covered gypsum board is disclosed in
U.S. Pat. No. 2,806,811 to Von Hazmburg. Von Hazmburg discloses a
board that primarily consists of a thick gypsum core that is encased in
a fibrous envelope consisting of both a manila sheet and a newsprint
sheet. These sheet layers can be made from a conventional multi-
cylinder paper making process.
[0006] Although conventional paper faced gypsum board, such as
that disclosed by Von Hazmburg, is acceptable for many applications,
it also has considerable drawbacks. A major drawback is durability.
Gypsum board is far more brittle than other building materials, such as
wood or masonry based materials. Paper faced gypsum boards,
therefore, chip and/or crumble under both compressive and tensile
loads. As a result, conventional gypsum board is easily damaged
during normal wear and tear within a dwelling, such as impacts with
people and/or furniture. Conventional gypsum board assemblies often
have low load carrying capacity and inadequate nail pull strength. As a
result, traditional gypsum board often cannot support the loads needed
to hang pictures or install shelving without the use of supplemental
fasteners.
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[0007] As a consequence of these drawbacks, efforts have been
made over the years to improve the durability and surface strength of
gypsum board. One particularly 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. More specifically, Baehr
replaces paper facing sheets with opposing layers formed, in part, from
glass fiber mats. This construction provides a stronger and harder
external surface and is an improvement over paper faced boards.
Although an improvement from the standpoint of durability, the use of
exposed fiber mats is problematic. Namely, workers handling such
boards are exposed to lose strands of fiber. This poses a health risk
and necessitates the use of protective gloves and/or masks. Thus,
GRG boards utilizing exposed facing sheets are not ideal.
[0008] A subsequent improvement is described in commonly owned
U.S. Pat. No. 4,378,405 to Pilgrim.
Pilgrim discloses a GRG
board that is faced on one or both sides with a porous, nonwoven
glass mat. However, the glass mat of Pilgrim is slightly embedded into
the slurry core. This is accomplished by vibrating the gypsum slurry to
cause it to pass through the porous openings in the mat.
[0009] Embedding the mat within the core results in a thin film of
slurry being formed 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. Despite eliminating the safety issues surrounding
GRG boards, Pilgrim ultimately failed to provide a board with sufficient
strength and durability.
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[0010] A further improved EGRG board is disclosed in commonly
owned U.S. Pat. No. 6,524,679 to Hauber, et al.
The EGRG
board of Hauber adds a polymeric compound to the gypsum slurry.
Suitable polymeric compounds may include, for example,
polyvinyidene chloride (PVDC), or polyvinylchloride (PVC), or similar
polymers. The polymer additive increases durability and board strength
and also creates a matrix within the slurry after it sets. Although
certainly an improvement over existing EGRG technology, Hauber did
not address issues associated with the durability of the exterior face or
the complete mechanical and chemical bonding of the exterior face to
the underlying gypsum slurry.
[0011] Thus, there still exists a need in the art for improved building
board construction. More specifically, there is a need in the art for a
board with a polymer matrix that provides enhanced durability, impact
resistance, water repellency, fire resistance, and load carrying
capacities. There is also a need in the art for a board that provides
these physical properties without unduly increasing the weight or cost
of the resulting board. The present invention is aimed at achieving
these objectives.
SUMMARY OF THE INVENTION
[0012] It is therefore one of the objectives of this invention to
utilize a
cementitious pre-coated fibrous mat in conjunction with an external hot
melt thermoplastic coating.
[0013] It is another object of this invention to provide a
thermoplastic
coating as a partial or complete surface covering for a cementitious
pre-coated fibrous mat.
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[0014] Yet another object of this invention is to provide a
thermoplastic coating over a pre-coated fibrous mat wherein the
thermoplastic coating includes additives for enhancing performance
characteristics.
[0015] A further object of this invention is to allow multiple product
variations to be achieved without changing the formulation of the hot
melt thermoplastic coating.
[0016] Still yet another object is to apply a hot melt thermoplastic to
a pre-coated fibrous mat to thereby enhance the mechanical and
chemical bonding between the thermoplastic and the mat.
[0017] It is also an object of this invention to produce a composite
building board with enhanced strength and reduced weight.
[0018] Another object of the invention is to reduce both the
manufacturing and capital costs associated manufacturing building
boards.
[0019] The foregoing has outlined rather broadly the more pertinent
and important features of the present invention in order that the
detailed description of the invention that follows may be better
understood so that the present contribution to the art can be more fully
appreciated. Additional features of the invention will be described
hereinafter which form the subject of the claims of the invention.
[0020] It should be appreciated by those skilled in the art that the
conception and the specific embodiment disclosed may be readily
utilized as a basis for modifying or designing other structures for
carrying out the same purposes of the present invention. It should also
be realized by those skilled in the art that such equivalent
constructions do not depart from the spirit and scope of the invention
as set forth in the appended claims.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0021] For a fuller understanding of the nature and objects of the
invention, reference should be had to the following detailed description
taken in connection with the accompanying drawings in which:
[0022] Fig. 1 is a perspective view of a composite building board
constructed in accordance with the present invention.
[0023] Fig. 2 is a cross sectional view of the composite building
board taken along Line 2-2 of Fig. 1.
[0024] Fig. 3 is a detailed view taken from Fig. 2 and showing the
thermoplastic coating applied to the underlying cementitious pre-
coated mat.
[0025] Fig. 4 is a detailed view of a prior art construction with a
thermosetting coating being applied to the cementitious pre-coated
mat.
[0026] Fig. 5 is a view of a roller coater used to apply the
thermoplastic coating of the present invention.
[0027] Fig. 6 is a view of a curtain coater used to apply the
thermoplastic coating of the present invention.
[0028] Fig. 7 is a view of a knife coater used to apply the
thermoplastic coating of the present invention.
[0029] Fig. 8 is a view of a spray coater used to apply the
thermoplastic coating of the present invention.
[0030] Similar reference characters refer to similar parts throughout
the several views of the drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0031] The present invention relates to a composite building board
construction. The board includes a set gypsum core and a fibrous mat
that is pre-coated with a cementitious layer. A thermoplastic coating is
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then applied over the cementitious layer. Additives can be added to
one or more of the layers to provide enhanced performance
characteristics. Also disclosed are various manufacturing techniques
for applying a hot melt thermoplastic coating to cementitious layer.
[0032] Fig. I is a perspective view of a composite building board 20
constructed in accordance with the present invention. Building board
20 is typically formed in long sheets in a continuous production line
process. The sheets are thereafter cut to a desired length. However,
the present invention is by no means limited to any specific board
dimensions or geometry. As noted in more detail hereinafter, board 20
includes an outer surface that is formed from a thermoplastic 22 that is
applied over cementitious pre-coated fiber mat 24 and a set gypsum
core. However, a pre-coated fiber mat 24 and thermoplastic coating 22
can also be applied to opposing sides of the set gypsum core.
Suitable two-sided manufacturing methods are disclosed in commonly
owned U.S. Patent Application 12/480,159, entitled "Plastic Coated
Composite Building Boards and Method of Making Same",
and published as US 2010/0055431 on March 4, 2010. The
thermoplastic layer 22 and pre-coated fiber mat 24 can also be
optionally applied to the side edges of board 20.
[0033] As noted by the cross-sectional view of Fig. 2, the composite
board 20 includes an intermediate layer consisting of a cementitious
pre-coated fibrous mat 24. In the context of this invention "pre-coated"
references the cementitious material being deposited on the underlying
fibers 36 prior to the mat 24 being incorporated into a building board
20. It is envisioned
that the mat 24 would be supplied to the
manufacturing facility with the cementitious coating 32 being previously
applied as a facer. Alternatively, the cementitious coating 32 could be
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applied at a different phase of the manufacturing process but prior to
assembly of the building board 20.
[0034] The preferred construction of the mat 24 is next described in
connection with Fig. 2. The mat 24 is preferably defined by first and
second portions (26 and 28), with the first portion 26 comprising the
cementitious layer 32 and the second portion 28 comprising fibers 36
that are at least partially embedded into the cementitious layer 32. The
cementitious layer 32 can be formed from set gypsum, gray or white
portland cement, calcium carbonate, or any combination of the
forgoing. Cementitious layer 32can be latex based and may, or may
not, include polymer additives. The upper surface of the cementitious
layer 32 includes a plurality of pores 34 of varying size and depth.
Pores 34 generally range in depth between .05 to 1mm and are largely
the by-product of foaming agents present within the cementitious layer.
The pore size can also be varied by altering the ratio of organic and
inorganic fillers within the cementitious layer. These pores 34 are the
result of the cementitious coating 32 have a rough and textured
surface. As note below, these pores 34 function as bonding sites
during the application of the thermoplastic.
[0035] The fibers 36 of the second portion 28 are preferably non-
woven, randomly aligned glass fibers 36. The fibers 36 can be held
together in a binder. Suitable binders include resins, such as urea-
formaldehyde. The fibers 36 can also be long inorganic fibers, such as
glass fibers, and can also be continuous, non-continuous, or blends of
both. The fibers 36 can alternatively be formed from organic filaments.
In a further embodiment, mineral fibers are used. Small diameter fibers
are preferred; namely, fibers with an average diameter of between
approximately 13-16 pm. The resulting fibrous mat 24 is sufficiently
porous to allow for the passage of gypsum slurry between the
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individual fibers 36, whereby open fibers 36 can be coated, or
substantially coated, with gypsum slurry.
[0036] The glass fibers 36 of the mat 24 are further defined by upper
and lower extents (38 and 42). As noted in the detailed view of Fig. 3,
the upper extents 38 of the fibers 36 are embedded within the
cementitious pre-coating 32, thereby binding the two portions of the
mat 24. A binder can be added to the lower extents 42 of the fibers 36.
Even with a binder, prior to mat 24 being applied to a gypsum core, the
lower extents 42 of fibers 36 are loose and capable of being embedded
in slurry. The lower extents 42 of the fibers 36 define a fibermat that is
essentially encased in slurry during subsequent manufacturing steps.
[0037] Suitable cementitious pre-coated fibrous mats include any of
the Coated Glass Facer (CGF) products currently sold and
manufactured by Atlas Roofing Corporate of Meridian, Mississippi.
Atlas' CGF products include a substrate that is formed from a glass
fiber wet process mat and that is coated with a latex based, inorganic
filled, coating. The glass mat serves as reinforcement for the coating
and any added substrates. Atlas' CGF products are more fully
described in the following U.S. Patents
: 5,102,728, 5,112,678, and 7,138,346. Other
suitable CGF products are manufactured by Johns Manville of Denver,
Colorado, Owens Corning, Inc. of Summit, Illinois, and Elk Corporation
Dallas, Texas. Alternatives to commercially available pre-coated mats
can also be used to reduce costs.
[0038] As noted in Fig. 2, the cementitious pre-coated fibrous mat 24
is subsequently adhered to a core of gypsum slurry. A dense layer 44
of gypsum slurry is formed intermediate the pre-coated mat 24 and
core 46. Both the dense slurry layer 44 and the core slurry layer 46 are
subsequently cured in an oven in a manner known in the art. In the
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preferred embodiment, the dense slurry layer 44 penetrates the lower
extents 42 of the glass fibers 36 by approximately 90% to 100%. In
other words, 90% to 100% of the length of the exposed glass fibers 36
(i.e. the portion of the fibers 36 not embedded into the cementitious
layer 32) are covered by the dense gypsum layer 44. This permits the
lower extents 42 of the glass fibers 36 to be substantially encased.
Furthermore, the cementitious layer 32 acts as a boundary and largely
prevents the dense layer 44 from penetrating the outer surface of the
board 20. However, some slurry from core 46 can penetrate the outer
surface of board 20.
[0039] The dense slurry layer 44 preferably includes a polymer
additive to increase the overall durability and surface strength of the
board 20. The polymer additive also preferably facilitates a strong
chemical bond between itself and core. These polymer additives will
react and chemically bond with polymers in adjacent layers. Suitable
polymeric additives may include, for example, polyvinyidene chloride
(PVDC), or polyvinylchloride (PVC), or similar polymers. Another
suitable polymer additive is a functionalized styrene butadiene (SBD)
latex that is available from Omnova Solutions of Fairlawn, Ohio. Yet
another suitable additive is silane or a functionalized silane (SiH4).
Silane compounds are ideally used in conjunction with other polymers
to facilitate coupling between the polymer to glass fibers 36. Silane is
also known as a stabilizing agent. Suitable silane compounds are sold
by Dow Corning. Still yet other polymer additives are described in U.S.
Pat. No. 6,524,679 to Hauber. Whatever additive is utilized, it should
be capable of providing covalent, allyl, Vanderwal, single and double
bonding to the adjacent coatings. The polymer additives referenced
above can be included in the thermoplastic layer 22, the cementitious
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pre-coating 24, as well as the dense and core set gypsum layers (44
and 46)
[0040] With continuing reference to Fig. 2, the core layer 46 of set
gypsum is bonded to the dense layer 44. The core 46 layer has a
density that is less than the density of the dense layer 44. The core
slurry layer 46 generally comprises the majority of board thickness and
extends to, and bonds with, the adjacent dense slurry layer 44. The
core slurry 46 can likewise include a polymer additive for the purpose
of adding durability and surface strength. The polymer additive within
core slurry 46 preferably chemically bonds with, and cross-links to, the
polymer additives within the dense slurry layers 44. Any of the above
referenced polymers are suitable for this purpose.
[0041] The hot melt thermoplastic coating 22 is applied over the
cementitious layer 32 and forms the exterior surface of the building
board 20. In the preferred embodiment, a hot melt thermoplastic
coating 22 with a melting point of between approximately 100 F to
500 F is utilized. The thermoplastic is preferably applied in a molten
state so that it can penetrate the pores 34 within the upper surface of
the pre-coating 32. The result is both a chemical and mechanical bond
between the coating and the mat 24. Namely, the thermoplastic
coating 22 cross-links with the polymer additive in the pre-coating 32.
Additionally, the molten thermoplastic entirely, or mostly, fills the pores
34 within the cementitious layer 32. Once the thermoplastic sets
and/or returns to a solid state, the filled pores 34 act as a root structure
that mechanically adheres the plastic coating to the underlying
cementitious pre-coated glass mat 24.
[0042] The preferred thermoplastic is Ethylene Vinyl Acetate (EVA)
applied at a thickness of between .1 grams to 35 grams per square
foot. Metallocene catalyzed polymers are also preferred. However,
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any of the following thermoplastic coatings materials, used singularly
or in combined, may optionally be used for the exterior coating 22:
Acrylonitrile butadiene styrene (ABS), Celluloid, Cellulose Acetate,
Ethylene-Butyl Acrylate, Ethylene-Methyl Acrylateõ Ethylene Vinyl
Alcohol (EVAL), Fluoroplastics (PTFEs, including FEP, PFA, CTFE,
ECTFE, ETFE), lonomers, Liquid Crystal Polymer (LCP), Metallocene,
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).
These above compounds may be blended with tackifying resins and/or
waxes as required for application of hot melts and/or desired physical
properties.
[0043] Any of the above referenced hot melt thermoplastics yields
sufficient adhesion between the plastic coating and the underlying
board. By contrast, and as noted in Fig. 4, the use of thermal setting
coatings have proven problematic. Namely, the application of thermal
setting coating to the surface of cementitious pre-coated fibrous mat 24
is subject to limited adhesion characteristics as a result of limited
penetration, binding, and area displacement characteristics. When one
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applies a thermal set coating to a cementitious pre-coated fibrous mat
24, said coating is limited in its binding characteristic due to a number
unfavorable circumstances relating to the application surface of the
cementitious pre-coating 32 embedded into the fibrous mat 24. With
thermal set coatings, only a film is left to occupy the invaded area once
the coating cures. This offers a relatively low adhesion quality in the
porous areas. A simple tape test can demonstrate the weakness of this
adhesion quality, wherein the tape once applied to the outer cured
thermal set coating can be easily pulled free liberating the coating
away from the previously covered area.
[0044] In contrast, adhesion of the thermoplastic coating 22 to the
cementitious pre-coating 32 is significantly stronger and more
uniformly complete in its coverage. The thermoplastic fully invades the
small surface pores 34 of the cementitious coating, whereby the pores
34 are completely, or mostly, filled with the thermoplastic. This
improved invasive characteristic is accomplished as a result of the
thermoplastic being applied in a hot or molten liquid form. In its hot or
molten liquid form, at the point where it is applied to the cementitious
pre-coated surface, the thermoplastic flows into pores 34 of the
cementitious surface, fully invading previously vacant or open areas.
The thermoplastic coating 22 cools immediately locking itself in a
rooted manner into the cementitious surface. A tape test on product
coated with the hot melt thermoplastic demonstrates that the tape ¨
when removed forcibly ¨ peels clean from the thermoplastic ¨ leaving
the external thermoplastic coating 22 on top of the cementitious pre-
coated fibrous mat 24, intact.
[0045] The thermoplastic coating 22 also serves as a novel
mechanism for delivery of a multitude of products built on one platform
using one coating type. The thermoplastic coating 22 can be altered to
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adapt to the specific end user requirement. For instance, each coating
within a laminate could have a different chemical composition and/or
physical property. Each layer could be formulated to have, or not
have, UV resistance and still be durable and capable of offering an
extended chemical cross linking mechanism for surface finishing paints
or adhesives, thereby making the single coating useful as an interior
product or a exterior product if the anti-UV additive were included.
Moreover, the thermoplastic coating 22 can be modified to achieve
intended results without necessarily altering the basic chemical make
up of the board 20.
[0046] The thermoplastic coating 22 can include any of a variety of
additives, such as fillers or polymeric compounds, to modify the
characteristics of the board 20 as needed. These additives include:
polar and non-polar polyolefenic compounds, isotactic and atactic
polymeric compounds, crystalline and amorphous polyolefenic
compounds, natural and synthetic tacifying resins as part of a
polyolefenic compound, directly applied low viscosity polyolefenic
compounds, the use of films bonded via Vanderwal forces and/or
valent or ionic bonding, films with low thermal conductivity,
microscopically non-continuous films for engineered molecular water
permeability, utilization of dissimilar molecular polymeric active sites
for improved molecular adhesion between dissimilar copolymers, non-
oriented polymer films, planar oriented polymer films, films with
random polymer orientations for film elongation, topographically
mirrored polymeric films for improved mechanical adhesion, and the
use of multilayered laminations. Any of these additives would form a
part of the external most stratum of the resulting building board 20 and
would impart certain beneficial physical properties.
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[0047] Fig. 5 illustrates a roller coater 48 for use in applying the
thermoplastic coating 22 directly to the cennentitious pre-coated glass
mat 24. The roller coater 48 includes both an application roller 52 and
a metering roller. 54 The gap between the application and metering
rollers can be adjusted and selected to achieved a desired application
rate, which is dependent, in part, on the rheology and temperature of
the applied coating. Both rollers (52 and 54) can be heated and
optionally have a roller hardness that creates the desired thickness on
the glass mat 24. The front and back faces of the board 20 can be
coated singularly or simultaneously as is known in the art. The
thermoplastic coating 22 may also be applied to one, two, three, four,
five or six, any one, any combination of, the board 20 surfaces.
[0048] Care must be taken to ensure that the gypsum within the core
46 does not calcine during the thermoplastic application. Although the
thermoplastic coating 22 is generally heated to the temperature of the
application coater (anywhere between 100 to 500 ), the fibrous mat
24 is never subject to prolonged exposure insomuch as the rollers are
in constant motion. As a result, there is no calcination of gypsum core.
[0049] The preferred surface hardness attained as a result of the
thermoplastic coating may result in a range of hardness's equal to a
minimum of about 50 to a maximum of about 150 on a Rockwell R
Hardness scale, or a minimum of about 15 to maximum of about 70 on
a Shore A and D Hardness scale. The preferred water vapor
permeability of the applied thermoplastic 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 film
translucence may range from .001 % to 100 %. The chosen
characteristics will depend upon the intended use of the final board 20.
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Potential uses include, but are not limited to, interior or exterior
sheathing, tile backer, shaft liner, ceiling tile, and or underlayment.
[0050] The thermoplastic coating may also 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. The thermoplastic coating upon
application may be engineered to offer desired surface topography that
may range from smooth profile (having measured trace lengths equal
to or about a minimum of .01) to a coarse profile equivalent to desired
specification. Applied film thicknesses of the above mentioned
thermoplastics may range from a minimum of .01 mils to and maximum
of 500 mils in thickness. Applied film thickness may be applied in one
or multiple applications at varying or equivalent application
temperatures and varying or equivalent application speeds.
[0051] Application of the thermoplastic coating may be conducted
immediately following the initial set of the gypsum substraight or
thereafter. The thermoplastic coating can be applied in any of a variety
of known ways, including: gravity fed, pump fed, forward or reverse
rotating hot melt roll coaters; gravity fed or pump fed hot melt curtain
coaters (note Fig. 6); slot die coaters; knife coating systems (note Fig.
7); gravity fed or pump fed hot melt spray systems (note Fig. 8); high
pressure low volume or low pressure high volume methods. The
thermoplastic coating may be applied in equal or uniform level or
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levels, or in unequal or non-uniform level or levels. The thermoplastic
coating may be applied by means of continuous or non-continuous
process method, although continuous processes are preferred.
[0052] The preferred continuous process method involves the
removal of the normal end process used to manufacture gypsum
building panels. The end process is replaced with a novel inline hot
melt coating process specifically designed to overcome the adverse
environmental conditions experienced with the manufacture of glass
fiber incorporated products. The preferred continuous process may
incorporate a minimum of 1 hot melt thermoplastic applicator or as
many as 50 hot melt thermoplastic applicators aligned or not aligned in
series, parallel, or both to allow a single or multiple thermoplastic
coating lines of base platform (blank) product to be produced
singularly, in pairs simultaneously, or groups of pairs simultaneously.
An alternative advantage of this continuous process is that during
normal production multiple products having varying and or different
physical properties and other performance characteristics can be
produced simultaneously. A further advantage is that the costs
associated with the manufacture of low margin products is now
capable of being offset, lowering the cost to produce these low margin
products as the invention herein disclosed is capable of simultaneously
producing high margin products, both of which can be manufactured at
equal to or optimized individual speeds as the thermoplastic coating
can be formulated or applied in varying levels at any one or any
multiple of applicator stations as desired or based on end user need.
The end product yielded from this novel continuous process is
substantially dust free, a novel and manufacturer/end-user health
improvement over all other gypsum build panel products currently
being produced.
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[0053] The present disclosure includes that contained in the
appended claims, as well as that of the foregoing description. Although
this invention has been described in its preferred form with a certain
degree of particularity, it is understood that the present disclosure of
the preferred form has been made only by way of example and that
numerous changes in the details of construction and the combination
and arrangement of parts may be resorted to without departing from
the spirit and scope of the invention.
[0054] Now that the invention has been described,
