Note: Descriptions are shown in the official language in which they were submitted.
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FOLDABLE REINFORCING WEB
FIELD OF THE INVENTION
The invention relates to a reinforcing web to reinforce a cementitious
wallboard or to
reinforce a wallboard joint compound, and a method of making the reinforcing
web, as well as, a
reinforcing web in a wallboard or in a wallboard joint.
BACKGROUND
The terminology, wallboard, refers to one or more panels or panel sections
having major
surface areas, which form gypsum wallboard or, alternatively, portland cement
wallboard or
alternatively, in situ polymeric foam panels of US 2007/0099524 Al. U.S.
5,017,312 discloses
chopped glass fiber mats tested for flexure and tensile properties according
to ASTM D 790-84a
"Standard Test Methods for Flexural Properties of Unreinforced and Reinforced
Plastics and
Electrical Insulating Materials," and ASTM D 638-84 "Standard Test Method for
Tensile
Properties of Plastics." The tests are performed on mats having random
oriented chopped fibers
and mats having directionally oriented chopped fibers.
US 7,141,284 B2 discloses a reinforcing web having a rewettable coating to
solubilize in
a slurry of a joint compound and form an adhesive bond with the joint
compound.
Open wallboard seams are formed between abutting sections of gypsum wallboard
that
meet side-by-side, or that meet at inside corners. To fill and cover an open
wallboard seam, a
wallboard joint is constructed, by applying a joint compound reinforced with
an imbedded
reinforcing tape. Additional seams can appear as cracks in the wallboard,
which are repaired by
constructing wallboard joints.
The joint compound is in the form of a shapeable slurry that fills the seam.
The
reinforcing tape is applied to extend across the filled seam, and to overlap
the edge margins of
the wallboard abutting the filled seam. It is desirable that the reinforcing
tape is foldable to form
a lengthwise crease. The crease is needed for conformance at an inside corner
of a wall meeting
another wall or a wall meeting a ceiling, wherein wallboard sections of the
walls and ceiling
meet one another at an angle less than 180 degrees. A wallboard joint is
constructed at the inside
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corner by applying joint compound to imbed the creased reinforcing tape.
A joint tape made of paper is capable of forming a crease for installation at
inside corners
wherein wallboard sections meet one another at an angle of less than 180
degrees. Moreover,
commercial tooling has been developed to use paper tape for machine
construction of a
wallboard joint. The tooling continuously dispenses the paper tape and
continuously dispenses a
joint compound slurry to imbed the tape. Further, the tooling shapes and
smoothes the joint
compound slurry. A drawback of paper tape is that the paper is weakened by
becoming saturated
with water from the slurry, and is incapable of passing air bubbles that are
trapped behind the
paper tape during construction of a wallboard joint.
Instead of a paper tape, a fabric tape has been used to reinforce a joint
compound. A thin
porous fabric has been manufactured with random laid glass fibers adhered to
one another with a
urea-formaldehyde binder. The tips of the glass fibers tend to poke out, which
is irritating to the
touch when handled by a worker. Moreover, a binder coated fabric resists being
folded, and is
not able to form a crease for conformance to an inside corner. Further, the
binder covered fabric
is not adaptable as is paper for handling by machine tooling for fabricating a
wallboard joint.
Such drawbacks deter using a binder coated fabric for reinforcing a joint
compound.
SUMMARY OF THE INVENTION
A reinforcing web for imbedding at least partially in a cementitious material
that hardens
from a slurry form includes multiple fibers joined together by a binder. At
least some of the
fibers have foldable portions, wherein the foldable portions have less binder
composition thereon
to increase flexure while folded without forming a crease or while folded to
form a crease, and
the foldable portions extend over a lengthwise central section of the web.
According to embodiments of the invention, the reinforcing web reinforces
either a
cementitious board or a wallboard joint compound.
According to an embodiment of the invention, a planar section of the web
reinforces a
major surface of a wallboard, and foldable portions of the web are of
increased flexure to be
foldable over lateral edges of a wallboard to reinforce the lateral edges.
According to another embodiment of the invention, a lengthwise central section
of the
web is foldable to form a crease for conformance to an inside corner formed by
a wallboard joint
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compound.
A method of making a reinforcing web comprises, applying a binder onto
multiple fibers,
wherein the fibers are oriented lengthwise in multiple directions, including
random directions,
predetermined directions, or a combination thereof to form a non- woven web,
removing at least
some of the binder from foldable portions of at least some of the fibers to
increase flexure of the
foldable portions at a fold of the foldable portions, and joining the fibers
to one another by curing
the binder thereon to resist tensile forces exerted in said multiple
directions.
In one aspect, the invention provides a method of making a non-woven
reinforcement web for
reinforcing a wallboard or a wallboard joint compound, comprising: assembling
fibers to form a
precursor of the non-woven reinforcement web at least some of the fibers
having one or more
foldable portions; dispersing a binder composition among the fibers either
before or after the
fibers form the precursor; varying the amount of the binder composition in
respective sections of
the precursor, wherein different sections of the precursor have different
amounts of the dispersed
binder composition; and curing the binder composition to form the non-woven
reinforcement
web having the fibers joined together by a cured binder composition, wherein
different sections
of the non-woven reinforcement web have different amounts of the cured binder
composition to
adjust flexibility of the different sections of the non-woven reinforcement
web, and wherein the
foldable portions extend in a lengthwise central section of the non-woven
reinforcement web, the
lengthwise central section comprising a width of between about 1 mm and about
3 mm, and
wherein the foldable portions have substantially less binder composition
thereon to form a crease
when folded.
In another aspect, the invention provides a non-woven reinforcement web for
reinforcing a
wallboard or a wallboard joint compound, comprising: multiple fibers joined
together by a binder
composition and forming the non-woven reinforcement web, at least some of the
fibers having
one or more foldable portions; and the binder composition being dispersed
among the fibers,
wherein the fibers in different sections of the non-woven reinforcement web
have different mass
distributions of the binder composition to adjust the flexibility of the
different sections of the
non-woven reinforcement web, and wherein the foldable portions extend in a
lengthwise central
section of the non-woven reinforcement web, the lengthwise central section of
the non-woven
reinforcement web comprising a width of between about 1 mm and about 3 mm, and
wherein the
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foldable portions have substantially less binder composition thereon to form a
crease when
folded.
In a further aspect, the invention provides a reinforcing tape for imbedding
in a joint compound,
comprising: multiple fibers joined together by a binder composition and
forming a thin non-
woven web; at least some of the fibers having one or more foldable portions,
wherein the
foldable portions extend in a lengthwise central section of the thin non-woven
web, and wherein
the lengthwise central section comprises a width of between about 1 mm and
about 3 mm; and
the foldable portions having substantially less binder composition thereon to
form a crease when
folded.
In a further aspect, the invention provides a method of making a non-woven
reinforcing web for
reinforcing a wallboard or a wallboard joint compound, comprising: applying a
binder
composition onto multiple fibers, wherein the fibers are oriented in multiple
directions; removing
at least some of the binder composition from foldable portions of at least
some of the fibers,
wherein the foldable portions extend in a lengthwise central section of the
thin non-woven web,
the lengthwise central section comprising a width of between about 1 mm and
about 3 mm, and
wherein said foldable portions are rendered capable of forming a crease upon
being folded; and
joining the fibers to one another by curing the binder composition to form the
non-woven
reinforcing web.
According to an embodiment of the method includes, removing substantially all
of the binder
from foldable portions of at least some of the fibers to increase flexure of
the foldable portions at
a fold of the foldable portions and to form a crease in the fold.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention will now be described by way of example with
reference to the
accompanying drawings.
Fig. 1 is a schematic view of a first embodiment of a reinforcement tape.
Fig. 2 is a schematic view of a roll of tape according to one of the
embodiments of a
reinforcement tape.
Fig. 3 A is schematic view of a portion of a manufacturing system and
apparatus.
Fig. 3B is a schematic view of another portion of a manufacturing system and
apparatus.
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Fig. 4 is a schematic view of a vacuum table of a manufacturing system and
apparatus.
Fig. 4A is a view similar to Fig. 4 of another embodiment of a vacuum table.
Fig. 5 is a schematic view of a slitting apparatus of a manufacturing system
and apparatus.
Fig. 6 is a schematic view of a second embodiment of a reinforcement tape.
Fig. 7 is a schematic view of another embodiment of a reinforcement web.
Fig. 8 is a schematic view of the reinforcing web of Fig. 7 providing a facing
on a cementitious
material to form a board.
Fig. 9 discloses a boxplot of test data in a test for Gurely Stiffness by
Sample.
Fig. 10 discloses a boxplot of test data in a test for Flexural Strength (PSI)
by Sample.
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DETAILED DESCRIPTION
The invention relates to a fiber reinforcement web to at least partially imbed
in a
cementitious material, and methods for making the same. The reinforcement web
is at least
partially embedded in the cementitious material that is hardened from a slurry
form to form a
wallboard. The fiber reinforcement web permeability enables penetration by the
cementitious
material in slurry form to at least partially imbed the web in the
cementitious material to
reinforce the cementitious material. The imbedded web reinforces the hardened
cementitious
material, adding to its flexural strength and its tensile strength, i.e.
resistance to deflection and
resistance to cracking and fracture due to strain induced by external tensile
forces and/or due to
internal strain.
The relative permeability of the web, due to the sizes of pores or spaces
between the
fibers, and the relative viscosity of the slurry determine to what extent the
web becomes
imbedded in the slurry. A web of lower permeability, smaller pores or spaces
between the fibers,
promotes penetration of a lower viscosity slurry and tends to imbed at the
surface of a lower
viscosity slurry, particularly for a slurry mixture of the lower viscosity
slurry and a higher
viscosity slurry. A web of higher permeability, larger pores or spaces between
the fibers, can
promote penetration of a lower viscosity slurry, and can embed deeper, below
the surface of the
slurry. Further, a web of higher permeability is required to promote
penetration of a higher
viscosity slurry.
A slurry wetting agent applied to coat the fibers further promotes wetting of
the fibers by
the slurry together with penetration of the web by the slurry. A solvent
activated adhesive
coating on the fibers further promotes adherence of the fibers to a hardened
cementitious
material. For example, water is a solvent of a gypsum cementitious slurry or
of an alkali
cementitious slurry, which activates a water activated adhesive coating on the
fibers to and
adhesive state for adherence to a hardened wallboard or hardened joint
compound.
Further, the invention relates to a reinforcement web to reinforce a
cementitious material,
wherein the web is constructed with a varied flexibility for foldability and
creasability and for
achieving a result including but not limited to, bending the web and/or
folding the web and/or
creasing the web to conform the web to the shape or shapes of the cementitious
material being
reinforced by the web.
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The fiber reinforcement web is constructed for flexibility or flexure,
foldability and
creasability at one or more selected locations on the web. The flexibility or
flexure, foldability
and creasability varies across the width of the web or alternatively in
another direction.
The fiber reinforcement web is constructed with chopped reinforcement fibers
bonded
together by a binder composition dispersed among the fibers and cured, i.e.,
solidified, to bond
the fibers together. The binder composition is dispersed with a lower binder
mass distribution
and a higher binder mass distribution in respective continuous lines or
continuous areas that
extend lengthwise of the web or alternatively in another direction.
The lines or areas extend continuously throughout a dimensional measurement of
the web
area to include the web thickness, such that a section of the web within the
lines or areas
including the web thickness is constructed with relatively less binder
composition to adjust or
induce flexibility, foldability and creasability. Alternatively, the section
of the web is constructed
with substantially less binder composition to adjust or induce foldability
and/or creasability. In
the section of the web, the binder composition is dispersed with a relatively
lower binder mass
distribution than elsewhere in the web.
The fiber reinforcement web is made with a selected thicknesses. According to
an
embodiment of the invention, a fiber reinforcement web having a maximum
thickness of a paper
drywall tape is adapted for use in fabricating a drywall joint. The drywall
tape is creased
lengthwise for conformance to an inside corner. According to another
embodiment of the
invention, a fiber reinforcement web having a thickness of a wallboard facing
sheet is adapted
for use in fabricating a cementitious wallboard. The fiber materials, lengths
and thickness, the
web permeability and thickness, and the binder composition viscosity are
selective to promote
penetration of the intended slurry composition and adherence of the fibers to
the cementitious
composition. The fiber materials, lengths and thickness, and the web thickness
are selected to
promote flexure strength and tensile strength of the fiber reinforced
cementitious.
Fig. 1 discloses a thin non-woven reinforcement web 104 of multiple fibers 102
in which
the fibers 102 are laid non-woven to provide a reinforcement tape 100. For
purposes of
illustration a small section of the web 104 is disclosed to indicate the
fibers 102. The fibers 102
comprise a high tensile strength material, including but not limited to glass
or a polymer, for
example, a polyester. Further, the fibers 102 are water resistant when
manufactured of glass, a
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,
crystalline polymer or a thermoset polymer. The fibers 102 are alkali
resistant when
manufactured of either AR glass or polymer coated glass.
According to an embodiment of the invention, the fibers 102 are chopped or
severed to
lengths of about 0.75 inch (19.05 mm.) to about 1.5 inch (38.100 mm.). The
fiber diameters
comprise one of about, 11 gm., 13.5 gm. or 16 gm. The distribution of the
fibers 102 in the web
104 provides a web thickness preferably equal to that of a commercially
available, cellulosic
paper joint tape, about 0.18 mm., plus or minus allowable dimensional
tolerances. The web 104
has a width of about 2 inches (50 mm.) desirably about equal to or less than
that of a
commercially available, paper joint tape. Thereby, the web 104 has dimensions
capable of
substituting for a paper tape that is used in commercial tooling to fabricate
a wallboard joint.
Further, the distribution of spaces between adjacent fibers 102 provides the
web 104 with
openings for passage of a commercially available joint compound in slurry form
during a process
of imbedding the web 104 in the slurry to make a wallboard joint.
Further, the web 104 in the form of a joint tape 100 is of continuous length,
and has
lengthwise lateral sections 106, 108 adjoining a lengthwise central section
110 that encompasses
a lengthwise central axis 112 of the web 104. The fibers 102 in the lengthwise
lateral sections
106, 108 are joined together by a binder composition 114 thereon. The binder
composition 114
joins the fibers 102 with one another. The fibers 102 in the web 104 are laid
flatly and extend in
multiple directions, including random directions, predetermined directions, or
a combination
thereof to resist tensile forces exerted in such multiple directions. Thereby,
the fibers 102 resist
tensile forces exerted in said directions when the fibers 102 are imbedded in
a joint compound.
The joint compound will be reinforced by the imbedded fibers 102 of the web
104 to resist
cracking under stress when forces are exerted on a wallboard joint formed by
the reinforced joint
compound. Spaces among the fibers 102 provide passages through the web 104 for
passage of
joint compound slurry. As an advantage compared to paper joint tape, the
passages permit escape
of air from being trapped behind the web 104. The fibers 102 provide a web 104
that comprises a
non-woven mat or fleece in which the fiber lengths lie flatly in the thickness
plane of the web
104, and extend lengthwise in multiple directions, including random
directions, predetermined
directions, or a combination thereof.
The lengthwise central section 110 of the web 104 is about 1 mm. to about 3
mm. wide.
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The lengths of respective fibers 102 are less than the overall width of the
web 104. The lengths
of respective fibers 102 are greater than the width of the central section 110
of the web 104. The
web 104 of the present invention must be capable of lengthwise folding to form
a crease. The
crease is needed for conformance at an inside corner where two sections of
wallboard meet at an
angle less than 180 degrees.
In an embodiment of the invention, the lengthwise central section 110 is
foldable to form
a lengthwise crease, extending preferably along the axis 112. The fibers 102
that have the binder
composition 114 thereon tend to resist being creased. Thus, some of the fibers
102 have foldable
portions 116 that extend over the central section 110, and are free of the
binder composition 114
so as to crease upon being folded. In an alternative embodiment of the
invention, the foldable
portions 116 of at least some of the fibers 102 in the lengthwise central
section 110 have less
binder composition 114 thereon than do the fibers 102 in the lengthwise
lateral sections 106,
108, so as to crease upon being folded.
The lengths of the fibers 102 are less than the overall width of the web 104.
The lengths
of the fibers 102 are greater than the width of the central section 110, such
that the fiber lengths
extend in the central section 110, further project outwardly from the central
section 110, and into
at least one lateral section 106, 108, wherein they are joined with other
fibers 102 by having the
binder composition 114 thereon.
Construction of a wallboard joint is performed either by manipulating hand
tools, or by
using commercial machine tooling. A paper type joint tape can be manually
handled by a human
worker who applies the tape by hand, and uses hand tools to imbed the tape in
a slurry of joint
compound, and to spread and smooth the joint compound to make a wallboard
joint.
Alternatively, commercial machine tooling continuously applies a joint
compound slurry
and a paper type joint tape while continuously imbedding the paper type joint
tape in the slurry,
and spreading and smoothing the joint compound to make a wallboard joint.
An embodiment of the tape 100 according to the invention is intended as a
replacement
for paper type joint tape for use in commercial machine tooling or for manual
handling, to make
a wallboard joint. Accordingly, an embodiment of the web 104 has about the
same dimensions as
the paper type joint tape, or less. Further, the web 104 has a suppleness
about that of paper tape
for ease in handling and constructing a wallboard joint by hand tools or
commercial machine
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tooling. Further, the web 104 of the present invention is rolled up on itself,
Fig. 2, while in the
form of a reinforcing tape 100, and undergoes unrolling from a roll 200 of the
tape 100, for
application onto a wallboard joint and imbedding in a joint compound slurry.
The web 104 must be capable of forming a crease for installation and
conformance at an
inside corner. Further, the web 104 of the present invention must have smooth
fiber surfaces to
avoid irritation to a human skin while being handled by a worker.
A process of making the reinforcement web 104 or tape 100 will now be
described. The
fibers 102 are chopped or severed to lengths of about 0.75 inch (19.05 mm.) to
about 1.5 inch
(38.100 mm.). The fibers 102 are commercially purchased as chopped fibers 102.
Figs. 3A and 3B disclose a system and apparatus 300 to manufacture the web 104
and/or
reinforcing tape 100. In Fig. 3A, the short length fibers 102 are commercially
purchased and are
amassed into a slurry 302 by mixing with a slurry solution comprised of water
enhanced with a
surfactant and a viscosity increaser. The slurry 302 comprises 0.1212 % solids
of a soluble
surfactant and 0.0072% solids of a soluble viscosity enhancer and water to
total 102,000 gallons
(386,112 liters)of slurry solution mixed with fibers 102. The slurry 302
comprises an
agglomerate of the fibers 102 and slurry solution, and is capable of settling
or slumping to form
a thin and uniform layer. The slurry 302 emerges from a head box dispenser 304
that uniformly
distributes the slurry 302 in a uniform layer on a forming wire 306. The
forming wire 306
comprises a perforated, non-woven flat fabric of a non-stick material, such
as,
polytetrafluoroethylene (PTFE). The non-woven fibers 102 of the slurry 302 are
wet laid flatly
on the forming wire 302, and extend lengthwise in multiple directions,
including random
directions, predetermined directions, or a combination thereof to form the non-
woven web 104.
The fibers 102 in the web 104 are held together by the slurry solution, and by
support against the
forming wire 306, while the web 104 and forming wire 306 are conveyed by
industry standard
conveyers 308 to pass over a first vacuum box 310. The first vacuum box 310
removes excess
solution by suction, impelling the water in the web 104 and ambient air
downwardly, as
indicated by the arrows, through the perforated forming wire 306. The removed
solution is
collected in a collection tank 312 for recycled use in the system 300. The
fibers 102 are drawn
against the forming wire 306 by the suction to form a web thickness about
equal to that of a
paper joint tape.
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In Fig. 3B, the conveyed web 104 is then transferred from the forming wire 306
onto a
saturator wire 314, of similar construction as the forming wire 306. The web
104 on the saturator
wire 314 is conveyed by industry standard conveyors 316 and passes under a
curtain coater 318
of the system and apparatus 300, which applies a falling, flowing curtain of
fluent binder
composition 114 onto the web 104. The binder composition 114 distributes among
the fibers
102. The fluid binder coats the web 104 and adheres to the tips of the fibers
102, as well, to
smooth the surfaces of the fibers 102 for non-irritating contact with a
person's skin. The web 104
is conveyed continuously lengthwise while being coated with a solution of the
binder
composition 114.
In Fig. 3B, the web 104 while on the saturator wire 314 passes over a second
vacuum box
320, directly aligned vertically under the curtain coater 318. The second
vacuum box 320 draws
a vacuum (reduced air pressure) to remove excess fluent binder composition 114
by suction from
the fibers 102. The removed binder composition 114 is collected in a
collection tank 322 for
recycled use in the system 300. Essential amounts of the binder composition
322 remain on the
fibers 102 for subsequent joining of the fibers 102 together in the binder
coated portions of the
web 104.
Further, in Fig. 3A, the saturator wire 314 and the conveyed, binder coated
web 104 pass
over a top surface 324 of a vacuum table 326. A motor driven vacuum pump 328
draws air from
an interior 330 of the vacuum table 326, which draws a vacuum (reduced air
pressure) in the
interior 330 of the vacuum table 326, while one or more water jet nozzles 332
focus a stream of
water 334 from above.
In Fig. 4, the surface 324 of the vacuum table 326 has a lengthwise, narrow
slot 400 over
which the lengthwise central section 110 of the web 104 is conveyed. In
preferred embodiment
of the invention, The nozzles 332, in Fig. 3, focus the stream of water 334 in
a narrow pattern
aligned with the lengthwise slot 400 to impinge the lengthwise central section
110 of the web
104. Water is a solvent for the uncured binder composition 114. A solvent 334
other than water
can be dispensed to impinge a binder composition 114 that is soluble in the
solvent 334 other
than water. Water dispenses from each water jet nozzle 322 and passes through
the foldable
portions 116 of the fibers 102 that extend into the narrow central section 110
of the web 104. The
water is vacuum drawn by the reduced air pressure of the vacuum table 326,
through the central
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section 110 of the web 104 and into the slot 400 of the vacuum table 326. Fig.
4A discloses the
narrow slot 400 transverse or crosswise to the lengthwise central section 110.
The stream of
water 334 is focused in a narrow pattern by an appropriate number of the
nozzles 332 of Fig. 4,
to impinge the lengthwise central section 110 of the web 104. The web 104 is
conveyed
lengthwise at a speed sufficient to avoid spreading of the stream of water 334
beyond the narrow
central section of the web 104 before the water is vacuum drawn into the slot
400 of the vacuum
table 36. In Figs. 4 and 4A, the water flows through the central section 110
of the web 104,
which dilutes the water soluble binder composition 114 and removes at least
some of the binder
composition 114 from at least some of the foldable portions 116 of the fibers
102 to increase
flexure and reduce stiffness thereof by reducing the amount of binder
composition 114, and
alternatively, removing substantially all of the binder composition 114 from
such foldable
portions 116 to permit folding and creasing of the foldable portions 116.
Alternatively, the binder
composition 114 is completely removed from the foldable portions 116 of the
fibers 102 that are
in the central section 110 of the web 104. The removed binder composition 114
is collected in a
collection tank 336 for recycled use in the system 300. The binder removing
operation is
narrowly focused on, and confined to, the longitudinal central section 110 of
the web 104 by the
combined, focused water jet and the width of the narrow slot 400 through the
surface 324 of the
vacuum table 326. The non-removed binder composition 114 remains adhered to
respective
fibers 102.
In Fig. 3B, thereafter the web 104 is conveyed through a curing oven 338 at
elevated
temperature, such that the binder composition 114 on the fibers 102 is heated
to a curing
temperature, which drives off the solvent and solidifies the binder
composition 114 to a
thermoset state. The binder 114 is cured and set to a thermoset state, wherein
the binder 114 is
solidified and becomes insoluble in water and other solvents, and joins the
fibers 102 together in
the web 104. The web 104 is rolled up to form the roll 200 of reinforcement
tape 100.
The binder composition 114 is cooled to ambient temperature after the web 104
leaves
the curing oven 338. The binder composition renders the fibers 102 more supple
to the touch.
However, the binder coated fibers 102 resist flexure when folded and resist
forming a crease
when folded. Moreover, the binder composition is applied to the fibers 102
accumulated on a
shaped conveyor belt surface, straight or curved, to form a web 104 having a
shape formed by
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and conforming to the shape of the conveyor belt surface. When hardened, the
binder
composition render the binder coated fibers 102 sufficiently stiff to retain
the web 104 with a
shape as formed. For example, the binder coated fibers 102 form a flat web 104
to provide a flat
major surface of a gypsum board or cement board. According to embodiments of
the invention,
the foldable portions 116 of at least some of the fibers 102 have less binder
composition thereon
to increase its flexure while folded, and preferably have substantially or
essentially all of the
binder composition removed, so as to form a crease while folded and creased.
The foldable
portions 116 are in the section 110 of the web 104 that is foldable.
The web 104 avoids having a rough texture that is irritating to human skin,
particularly
where tips of the fibers 102 are exposed, and particularly where the fibers
102 are exposed at the
surface of the web 104 and are prickly to the touch. Accordingly, a non-
irritating binder
composition 114 coats the fibers 102. An embodiment of a non-irritating binder
composition 114
comprises 3-10 grams of a matting agent, for example, a polymethyl urea resin
with about 0.6%
reactive methyl groups and primary particles of about 0.1 to 0.15 forming
agglomerates of
about 3.5 to 6.5 m. diameter, and a 20% solids solution of GP Resi-MatTm, a
urea formaldehyde
copolymer forming resin soluble in water, as a binder for wet laid glass fiber
mat, a commercial
product of Georgia-Pacific Building Products, Atlanta, Georgia. The preferred
solid is marketed
as PERGOPAK m5 a trademark of Albemarle Corporation, which refers to a
polymethyl urea
resin having a water content of 15 weight % H20 corresponding to the m5
designation and
forming a thermosetting urea-formaldehyde copolymer, condensation product or
reaction
product.
Alternatively, a non-formaldehyde fluid binder composition 114 comprises
Acrodur
950L, a water soluble thermosetting acrylic polymer binder cut to a range of
15% - 25% solids
from 50%-55% solids, for example, 200g of water as a solvent for 200g of
Acrodur.
According to an embodiment of the invention, the web 104 for use as a joint
tape 100 is
preferably about equal to the width of a paper joint tape. Fig. 5 discloses
another embodiment of
the invention, wherein the web 104 is conveyed through a slitter apparatus
500. The web 104 is
conveyed by a tow chain or by industry standard conveyors 504. A slitting
blade 502 is
disclosed, which may be circular or flat. The slitting blade 502 slits the web
104 lengthwise to a
desired width corresponding to the width of a wallboard joint tape, preferably
about equal to the
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width of a paper joint tape or less than the width of a paper joint tape, to
substitute for paper joint
tape in applicator tooling. Slitting with a sharp blade would leave sharp
edges on the severed
fibers 102, which would provide a source of skin irritation. Accordingly, the
slitter apparatus 500
has a blunt edge slitting blade 502 to slit through the web 104, while the
blunt edge makes
crushed edges on the fiber ends along the sections 106, 108, Fig. 1, of the
web 104. The crushed
edges are less irritating to skin than are sharp edges. Depending upon the
overall width of the
conveyed web 104, the slitter apparatus has a sufficient number of blades 502
to slit the web 104
lengthwise to form one or more joint tapes 100, side by side. Further, the
vacuum table 326 is
provided with one or more lengthwise slots 400 corresponding to the number of
central sections
110 of respective joint tapes 100 to be manufactured, side by side. Further,
the vacuum table 326
is provided with one or more lengthwise slots 400 corresponding to the number
of foldable
portions 116 are intended for the same single reinforcement web 104 of the
type disclosed by
Fig. 7 below. The slitter apparatus 500 slits the web 104 to form the
lengthwise lateral sections
106, 108 adjoining each lengthwise central section 110. Preferably the central
section 110 is
equidistant from lateral edges of the web 104. The tape 100 is rolled up on
itself to provide a roll
200 of tape. Thereafter, the tape 100 is dispensed by unrolling from the roll
200, either by hand
operation or by tooling operation.
Fig. 6 discloses another embodiment of the invention, wherein the tape 100 is
provided
with a fold line 600 that provides a guide for folding the tape 100 with ease.
The tape 100 is
folded along the central longitudinal axis 112 to provide a crease 600 along
the tape axis. The
tape 100 is then unfolded for the crease 600 to lie essentially flat and
provide a fold line. Further,
the unfolded tape 100 is rolled up on itself to provide a roll 200 of tape, as
in Fig. 2, having a
fold line 600 as a guide for folding and creasing the tape 100 in the future.
Thereafter, the tape
100 is dispensed by unrolling from the roll, either by hand operation or by
tooling operation. The
fold line 600 provides a guide for folding the tape 100 with ease along the
fold line 600 to
conform the tape 100 to an inside corner in preparation for imbedding in a
wall board joint. The
tape 100 can be folded, for example, ninety degrees, and return to its
original flat shape without
losing tensile strength. By removing the binder in the anticipated foldable
portions 116, the fibers
are free of the binder and are free to flex without fracturing in response to
being folded. This
feature differs from tapes in which their fibers are held by a binder, which
resists flexure of the
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fibers, and which causes the fibers to become weakened or fractured when the
fibers are flexed.
The fibers in the foldable portions 116 of the lengthwise central section 110
extend into the
binder coated lateral sections 106, 108 for the binder to bond the fibers to
other fibers in the tape
100, and to resist pull-out of the fibers from a hardened joint compound.
Further, a hardened
joint compound adheres to the fibers that bridge across the foldable portions
116 to the binder
coated lateral sections 106, 108 to reinforce the joint compound and provide
resistance to
cracking.
Fig. 7 discloses an alternative embodiment of a reinforcement web 104 to imbed
at least
partially in a surface of a cementitious material, for example, a cementitious
board formed by
hardening a slurry of a gypsum mixture or portland cement mixture or in situ
foamed polymeric
material. The reinforcement web 104 provides a facing or facing layer of the
cementitious
material. According to an alternative embodiment of the invention, the fibers
of the
reinforcement web are fabricated of polymeric material, AR glass fibers or an
alkali resistant
polymer coating applied to chopped glass fibers intended to imbed at least
partially in alkaline
cementitious material, for example, portland cement. The reinforcement web 104
has a flat
central section 110 of binder coated fibers 102 to form a flat surface of a
wallboard. Adjacent to
and contiguous with the central section 110, the reinforcement web 104 has
lengthwise foldable
portions 116, wherein at least some of the binder composition 114 is removed
from at least some
of the foldable portions 116 of the fibers 102 to increase flexure and reduce
stiffness thereof by
reducing the amount of binder composition 114. Alternatively, removing
substantially or
essentially all of the binder composition 114 from such foldable portions 116
permits folding and
creasing of the foldable portions 116. The foldable sections are adjacent to
lateral web sections
700 adjacent to respective lateral edges 702 of the web 104. The web sections
700 are coated
with the binder composition 114, or alternatively, the binder composition 114
is removed
partially or fully removed to adjust the flexure and/or foldability of the web
sections 700.
Fig. 8 discloses a cementitious composite material 802 forming a facing layer
of a
cementitious board 800 reinforced by the reinforcement web 104 of Fig. 7. The
entire web 104
is at least partially imbedded in the cementitious material 802 that is
hardened from a slurry
form. The foldable portions 116 are of reduced flexure to fold in conformity
with the lateral
edges 804 of the board 800. The flexure is increased by removal of a
corresponding amount of at
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least some of the binder composition 114 from the foldable portions 116. When
sharply defined
corner edges of the board 800 are desired, the foldable portions 116 are
capable of wrapping
around the edges and creasing along each of the foldable portions 116 by
removal of
substantially or essentially all of the binder from the foldable portions 116.
The foldable portions
116 are folded by flexure thereof to wrap by flexure around corresponding
edges 804 of the
board 800 to reinforce the edges 802 against damage due to impact or thermal
expansion and
contraction. Further, the foldable portions 116 are foldable with creases to
form substantially or
essentially sharp edges 804 on the board 800. Alternatively, the foldable
portions 116 are
foldable without creases for the edges 804 on the board 800 to have rounded
configurations. A
flat central section 110 of the web 104 covers a flat major surface of the
board 800. The opposite
major surface of the board 800 is covered by another reinforcement web 104a
that is at least
partially embedded in the cementitious material 802. The web sections 700 of
the web 104
overlap and cover corresponding edge sections 700a of the other reinforcement
web 104a, and
the overlapped sections 700 and 700a are at least partially imbedded in the
cementitious material
802.
To support the claims of increased foldability/flexibility, three different
tests were
conducted; Gurley Stiffness, Strength after bending, and ASTM D790-84a
Standard Test
Methods for Flexural Properties of Un-reinforced and Reinforced Plastics and
Electrical
Insulating Materials.
In three tests; Gurley Stiffness, Strength after bending, and ASTM D790-84a
(Flexural
Strength) the glass fiber mat with the "folding Point" or seam or reduced
binder area showed
results consistent with the mat being more flexible/foldable than a standard
glass mat of equal
weight and thickness.
For the Gurley stiffness test a standard glass mat was tested against a glass
mat with a
"folding point" or seam or area with reduced binder. A typical Gurley
Stiffness testing apparatus
was used. The glass mat with seam shows a Gurley Stiffness of 106.47 which is
lower than the
glass mat without seam 257.43. Using Statistical Analysis a one-way ANOVA
shows a
statistically significant difference or P value of less than 0.05. With the
glass mat with seam
being less stiff/more flexible than the glass mat without the seam.
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Table 1 Gurley Stiffness Test
0.9 lb Glass Mat 0.9 lb Glass Mat
Sample # With Seam without Seam
1 105.64 222.40
2 113.98 227.96
3 100.08 233.52
4 100.08 278.00
105.64 333.60
6 100.08 250.20
7 88.96 305.80
8 166.80 183.48
9 100.08 289.12
83.40 250.20
Average 106.47 257.43
One-way ANOVA: Gurley Stiffness versus Sample See Boxplot Fig. 9
5
Source DF SS MS
Sample 1 113936 113936 91.11 0.000
Error 18 22509 1250
Total 19 136445
S = 35.36 R-Sq = 83.50% R-Sq(adj) = 82.59%
Individual 95% CIs For Mean Based on
Pooled StDev
Level N Mean StDev
With Seam 10 106.47 22.85 (---*----)
without Seam 10 257.43 44.48 (___*____)
100 150 200 250
Pooled StDev = 35.36
For the Strength After Bending Test a standard glass mat was tested against a
glass mat
with a "folding point" or seam or area with reduced binder. Samples were
tested before and after
bending 180 . The samples with the binder reduced area showed a 34.53% loss of
strength which
was lower by almost half of the standard glass mat at 64.38%.
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Table 2 Strength After Bending Test
= Tensile Strene Tat)
Sample With Seam liVitiiout Seam
0 Deg 20.23 28.18
0 Deg 21.65 29.09
0 Deg 19.00 20.31
0 Deg 20.06 21.50
0 Deg 14.14 22.84
0 Deg 15.86 22.67
0 Deg 19.60 26.35
0 Deg 16.10 21.21
Axerage 18.33 24.02
180 Deg 7.98 6.28
180 Deg 15.16 7.81
180 Deg 12.79 9.58
180 Deg 11.83 9.71
180 Deg 12.04 9.80
180 Deg 14.42 9.75
180 Deg 9.24 8.17
180 Deg 9.22 8.63
180 Deg 10.50 8.56
180 Deg 12.58 7.27
Average 11.58 8.56
% loss of Strength 36.85 64.38
The following discussion refers to the ASTM D 790-84a "Standard Test Methods
for
Flexural Properties of Unreinforced and Reinforced Plastics and Electrical
Insulating Materials."
For this test a standard glass mat was tested against a glass mat with a
"folding point" or seam or
area with reduced binder. The test method used was ASTM D790-84a. And US
Patent 5,017,312
states ASTM D790-84a is used as a method used to quantify the flexural
properties of a glass
reinforced composite material. Procedure A was used with a support span of
30mm. The rate of
crosshead motion was 6.8mm/minute. The glass mat with seam showed a Flexural
Strength of
0.428 MPa lower than the standard glass mat at 0.789 MPa. Using Statistical
Analysis a one-way
ANOVA shows a statistically significant difference or P value of less than
0.05. The standard
glass mat shows a higher Flexural Strength.
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Table 3 ASTM D790-84a Test Method
Sample
' Width _ Thickness Peak Lail' Flexural Sttersiti Flexural Strength
I. D. mm mm N MPa PSI
"-
GlassMatSeam 12.7 0.194 0.017 0.310
45
GlassMatSeam 12.7 0.232 0.025 0.382
55
GlassMatSeam 12.7 0.224, 0.033 0.522
76
GlassMatSeam 12.7 0.234 0.025 0.379
55
GlassMatSeam 12.7 0.210 0.033 0.557
81
GlassMatSeam 12.7 0.236 0.028 0.420
61
Average 0.027 0.428
62
GlassMatControl 12.7 0.290 0.063 0.770
112
GlassMatControl , 12.7 0.270 0.044 0.577
84
GlassMatControl 12.7 0.275 0.056 0.722
105
GlassMatControl 12.7 0.250 0.048 0.680
99
GlassMatControl 12.7 0.280 0.065 0.823
119
GlassMatControl 12.7 0.295 0.097 1.165 169
Average 0.062 0.789 114
One-way ANOVA: Flexural Strength (PSI) versus Sample See Boxplot, Fig. 10
Source DF SS MS F P
Sample 1 8229 8229 15.78 0.003
Error 10 5215 522
Total 11 13444
S = 22.84 R-Sq - 61.21% R-Sq(adj) = 57.33%
Individual 95% CIs For Mean Based on
Pooled StDev
Level N Mean StDev -+ -- + ----- + -- +
GlassMatControl 6 114.50 29.30 ( ------ * )
GlassMatSeam 6 62.13 13.59 ( ------ * )
-+ ----- + ------ + ------ + --
50 75 100 125
Pooled StDev = 22.84
This description of the exemplary embodiments is intended to be read in
connection with
the accompanying drawings, which are to be considered part of the entire
written description. In
the description, relative terms such as "lower," "upper," "horizontal,"
"vertical,", "above,"
"below," "up," "down," "top" and "bottom" as well as derivative thereof (e.g.,
"horizontally,"
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"downwardly," "upwardly," etc.) should be construed to refer to the
orientation as then described
or as shown in the drawing under discussion. These relative terms are for
convenience of
description and do not require that the apparatus be constructed or operated
in a particular
orientation. Terms concerning attachments, coupling and the like, such as
"connected" and
"interconnected," refer to a relationship wherein structures are secured or
attached to one another
either directly or indirectly through intervening structures, as well as both
movable or rigid
attachments or relationships, unless expressly described otherwise.
The scope of the claims should not be limited by the preferred embodiments set
forth in
the examples, but should be given the broadest interpretation consistent with
the description as a
whole.
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