Title of Invention

" METHOD FOR MANUFACTURE OF GYPSUM BOARD AND DEVICE THEREFOR"

Abstract The present invention discloses a method of manufacture of gypsum board having fiber face sheets, comprising the steps of providing a first gypsum slurry (38) having a first consistency continuously passing through a first gypsum slurry transport receptacle (34), depositing a predetermined amount of said first gypsum slurry (38) onto at least a first continuous fiber face sheet (14), transporting said first continuous fiber sheet through a gypsum application station, providing a second gypsum slurry (44) having a second consistency and depositing said second gypsum slurry onto said first fiber sheet (14) and causing said second gypsum slurry to be essentially evenly distributed over an upwardly facing top surface of said first fiber sheet, wherein the step of depositing the second gypsum slurry (44) is preceded by a step of homogeneously mixing an additive into the first gypsum slurry (38) via a fluid feed in fluid communication with said first gypsum slurry transport receptacle (34). A gypsum board forming device for carrying out the method is also disclosed.
Full Text BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a method of manufacture of a gypsum board
and a device therefor, and more specifically to a method of manufacture of a gypsum
board permitting the targeted delivery of additives to specified locations.
2. Background Art
Gypsum board, and its production, has received attention in the building industry, and
especially for providing an easily worked building material the consistency of which is
available for general construction use. Desirable characteristics for gypsum board also
include a smooth working surface, consistent thickness throughout, and the ability to provide
finishing enhancements, such as paint or other protective coverings, thereon.
Recent developments in the manufacture of gypsum board have also added to the
durability and versatility of the uses to which gypsum boards may be put. For a fuller
discussion of the developments in the building board field is known as glass reinforced
gypsum (GRG) board, reference is made to the aforementioned U.S. Patent No. 6,524,679,
commonly owned with the present invention, and incorporated by reference has if fully
disclosed herein.
Manufacturing facilities for the production of gypsum board, whether or not glass
mats are utilized for the structural facings, are capital intensive in the costs of space,
equipment and in the down time during which a gypsum board production line is
reconfigured. For production of a variety of gypsum board products, for example, standard
paper faced gypsum board, glass mat backed board, etc., down time of the production line
represents a significant cost in the delay of production of gypsum board and in time wasted
by production workers who remain idle.
It has been further found that further finishing, e.g., painting, of a smooth gypsum
board surface, is made easier because the need for additional prefinishing steps, such as
priming, etc., may be minimized.
In addition, gypsum products, e.g., wallboard, tile, block, casts and the like, have
relatively little resistance to water when not modified by some chemical or physical

modification to address the problem of water absorption by the gypsum board. When gypsum
wallboard, for example, is immersed in water, the board may quickly absorb a considerable
amount of water, lose a great deal of its integrity and structural strength, and distort or swell in
different places. Many attempts have been made in the past to improve the water resistance of
gypsum products by adding waterproofing materials within the gypsum slurry. The most
common waterproofing material being used is a hydrophobic emulsion, usually an emulsion
comprising wax, paraffin, asphalt or a silicone compound, e.g., silanes and siloxanes.
As can be expected, modification of gypsum slurry to render it water resistant adds to
the cost of gypsum production, both in terms of the cost of the added substance, and in terms
of the additional equipment necessary to mix and deliver the water resisting compounds to
the gypsum slurry before application. Thus, it has been found desirable to provide a gypsum
board and manufacturing process thereof which can be manufactured at relatively high speed,
has high structural integrity and strength by virtue of using a mat of relatively low diameter
fibers, and may include in a face coating a polymeric additive material providing a surface
ideal for further finishing of the gypsum board, in addition to a means for delivering the
water resistant material targeted to the location on the gypsum board where it would be most
useful, that is on the surface of the finished gypsum board product. While the water resistant
capability is desirable for all of the gypsum layers in a gypsum board, it is now possible to
target specified layers of a multiplayer gypsum board that is made in accordance with the
aforementioned U.S. Patent No. 6,524,679, and other multilayer boards.
As a result of further development obtained through practice and further
consideration of the concepts disclosed and claimed the aforementioned U.S. Patent No.
6,524,679, it has been found additionally desirable to provide a means for delivering specific
desired additives to a specified multilayer density layer of a gypsum board panel, in order to
obtain specified desirable properties. For example, it has been found desirable to increase the
water resistance of the outer face surface of a glass mat gypsum panel made in accordance
with the teachings in the aforementioned U.S. Patent No. 6,524,679. Moreover, in
accordance with the teachings of that patent, the additives should only be targeted to that
layer, for example, the dense slurry layer, in which it is desirable to provide the desired
characteristic, so as to avoid unnecessary cost and weight to the final board panel by adding
costly and sometimes denser additives to layers of the gypsum board that will not provide as
much benefit as those to which the additives are targeted.

SUMMARY OF THE INVENTION
The present invention seeks to provide an improved gypsum product and process
therefor. In the present invention, contrary to the prior art, the gypsum product is made by
adding a hydrophobic (that is, water repelling or resisting, the terms being used
interchangeably) substance, such as, but not limited to, paraffin, wax, siloxanes and the like, in
specified locations of the gypsum board where the water repellent properties are most useful,
that is, at the surface and edges of the board. There is additionally provided in accordance with
an embodiment of the present invention a method for providing water resistance to a
predetermined surface of a gypsum product, the method comprising adding a hydrophobic
substance to gypsum slurry that is directed to a specified location on the gypsum board.
Accordingly there is disclosed and claimed herein a method of manufacture of
gypsum board having fiber face sheets, comprising the steps of providing a first gypsum
slurry having a first consistency continuously passing through a first gypsum slurry transport
receptacle, depositing a predetermined amount of said first gypsum slurry onto at least a first
continuous inorganic fiber face sheet, transporting said first continuous fiber sheet through a
gypsum application station, providing a second gypsum slurry having a second consistency
and depositing said second gypsum slurry onto said first fiber sheet and causing said second
gypsum slurry to be essentially evenly distributed over an upwardly facing top surface of said
first fiber sheet, providing a third gypsum slurry having a third consistency and depositing it
onto a second of said continuous fiber sheets, said second inorganic fiber sheet having top
and bottom surfaces, thereby coating said top surface of said second fiber sheet with said
third gypsum slurry, homogeneously mixing an additive into one of said first, second or third
slurries, prior to the steps of providing the gypsum slurries, applying said second inorganic
fiber sheet onto the second gypsum slurry thereby sheathing said second gypsum slurry
within said first and second fiber sheets to form a wet gypsum board product.
For use with an inorganic fiber, such as that disclosed in aforementioned U.S. Patent
No. 6,524,679, the method of manufacture of gypsum board having face sheets comprising
inorganic fiber, preferably randomly oriented inorganic fiber, comprises the steps of depositing
a predetermined amount of first gypsum slurry having a first consistency onto at least one
continuous sheet of randomly aligned inorganic fiber material having random interstices
between the fibers by passing at least one continuous inorganic fiber sheet through a gypsum
application station, the station including two applicator wheels through which pass the
inorganic fiber sheet, so as to cause the first gypsum slurry having a first consistency to
penetrate through the random openings between the inorganic fibers and thereby to coat both

top and bottom surfaces of the inorganic fiber material with the gypsum having a first
consistency, directing the first inorganic material from the gypsum slurry application station to
a first forming plate, depositing a second gypsum slurry having a second consistency on the
first inorganic fiber material and causing the second gypsum slurry to be essentially evenly
distributed over an upwardly facing top surface of the first inorganic fiber sheet, applying a
third gypsum slurry having a third consistency to a second of at least one continuous inorganic
fiber sheets, and causing the third gypsum slurry to penetrate essentially completely through
random interstices in the second inorganic fiber sheet, applying the second inorganic fiber
sheet onto the second gypsum slurry thereby sheathing the second gypsum slurry within the
first and second inorganic fiber sheet to form a wet gypsum board, passing the wet gypsum
board through a board forming station having a lower forming plate and an upper forming
plate, the upper forming plate comprising sections and defining at least one predetermined
angle relative to the lower forming plate, the vertical separation between the lower plate and at
least one section of the upper plate having a predetermined vertical dimension substantially
equal to the desired thickness of the manufactured gypsum board. Alternatively, a forming
wheel may be utilized to provide gypsum board having a predetermined thickness. Optionally,
an edger bar may be used to smooth and otherwise complete the surface finish of the gypsum
board. In a second embodiment, the method includes adding one or more polymeric additives
to the gypsum slurry of one or both surfaces.
In another embodiment of the present invention, a multilayer gypsum board comprising a
first layer of set gypsum comprising a first layer of a mixture of set gypsum having an outer
surface and at least one polymeric compound entrained within the set gypsum, and being
impregnated within a thin sheet of randomly aligned inorganic fibers, the outer surface of the
sheet being essentially encased within the set gypsum and polymeric compound, a second layer
comprised of set gypsum, the set gypsum in the second layer being of a lower density than the
set gypsum in the first layer; and a third layer having an outer surface comprising set gypsum
impregnated with a second thin sheet of randomly aligned inorganic fibers, the outer surface of
the third sheet being essentially encased within the set gypsum of the third layer; the set gypsum
in the first being integrally bonded to the gypsum of the second layer and the set gypsum in the
second layer being bonded integrally to the gypsum in the third layer.
One feature of the invention is the use of a turbulator mechanism in the additive
delivery assembly. In a gypsum board forming device comprising a supply of continuous
sheet of material, a gypsum slurry mixer including a gypsum delivery mechanism, disposed
at least at one gypsum delivery station for delivering the gypsum slurry onto the continuous

sheet, at least one additive assembly connected to an additive fluid feed for adding a
homogenous stream of an additive to the first gypsum slurry in a first gypsum slurry
transport receptacle, a gypsum core delivery mechanism including a second gypsum slurry
transport receptacle, a sheet joining station for joining the continuous sheet to the core
gypsum, and a gypsum conveyor line, having a belt with a surface for conveying formed
gypsum board from the sheet joining station, the additive assembly including an additive
delivery port in fluid communication with the additive fluid feed, a turbulator disposed in-
line with the additive fluid feed of at least one of the gypsum delivery mechanisms, the
turbulator comprising a fluid constrictor having an outlet, the fluid constrictor outlet being
disposed adjacent the gypsum slurry stream being transported through the first gypsum slurry
transport receptacle.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 is a diagrammatical, cross-sectional view of the gypsum board forming station
according to the present invention;
Fig. 2 is a detailed, cross-sectional, diagrammatical view of the vibrator sub-assembly
shown in Fig. 1;
Fig. 3 is a detailed, cross-sectional, diagrammatical view of Fig. 1, showing the top
sheet sub-assembly according to the present invention;
Fig. 4 is a schematic illustration of the structural elements used to provide the emulsion
mixing and delivery system to the desired layers of the gypsum board;
Fig. 5 is a detailed plan view of an embodiment of the invention;
Fig. 6 is a detailed perspective view of a single one of the inventive additive delivery
systems; and
Fig. 7 is a perspective partially cutaway or unassembled view of the inventive system
shown in Figs. 5 and 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the diagrammatical, cross-sectional illustration of Fig. 1, the board forming station
10 of an inventive embodiment of the inventive plant is shown. Although illustrated in cross-
section, the station 10 is shown diagrammatically to clearly depict the separate elements in
relation to each other. Modifications to the arrangement are possible and distances between
the separate elements are not to scale for simplicity of illustration, but a pragmatic and
efficient arrangement will come to mind to a person having ordinary skill in the art.
The inventive plant 10 comprises a supply roll 12 that provides feed of a continuous
sheet of facing material that, in the arrangement shown, defines a bottom-facing sheet 14.

The supply roll 12 may feed out a sheet comprising any conventional material used in
gypsum boards, for example, paper or paper board, but for purposes of the present invention,
the material of bottom facing sheet 14 preferably comprises a mat of long inorganic, e.g.,
glass, fibers which will be more clearly described below with reference to the formation of
the inventive gypsum board product, when the inorganic fibers comprise a glasso-glassive
fiber, the products being, sometimes referred to herein as glass reinforced gypsum ("GRG")
boards.
The supply roll 12 pays out the continuous bottom facing sheet 14 over a first
forming table 16, having an upwardly facing surface 18, provides a working surface for
further processing of the bottom facing sheet 14. The first forming table 16 also provides a
support for creaser wheel assembly 20, disposed athwart the surface 18.
The sheet 14 may be extracted from the supply roll 12 by motion of the sheet being
pulled through the board forming station 10 by the belt line, as will be described. The two
creaser wheels are vertically disposed within the creaser wheel assembly 20, one set of
wheels 22 above the bottom facing sheet 14 cooperate with a second set of wheels, referred
to as the wheel anvil 22', below the sheet 14. The creaser wheels 22, 22' rotate on axles and
produce partially cut edge creases on the sheet 14 adjacent to each of the longitudinal edges
of the bottom-facing sheet 14. The edge creases are spaced to allow varying fold thicknesses
and to cause the edges to turn upwardly so as to retain slurry poured onto the bottom-facing
sheet 14 downstream of the creaser wheel assembly 20, as is described below.
A continuous mixer 30, accepting raw materials, i.e. stucco, plaster, gypsum (in
powder form), water and other additives, through one or more inlets, one of which inlets 32
is shown in Fig. 1. The mixer 30 provides a mixing capacity that formulates a desirable
density of wet gypsum slurry by, for example, rotating a mixing blade (not shown) via a
drive shaft 33. Because it is a desirable feature for this invention to produce a multi-layer
gypsum board, the mixer 30 may comprise separate mixing chambers (not shown in Fig. 1)
for providing separate, and different slurry mixtures. A continuous mixer, such as that
utilized in this invention, is described and illustrated in commonly-owned U.S. Patent No.
5,908,521, which is incorporated by reference as if fully set forth herein.
The continuous mixer 30 thus provides several outlets for gypsum slurry each having
varying desirable characteristics depending on the function of the slurry layer for which any
specific outlet is producing gypsum slurry. Each outlet includes an output control for
controlling the amount of gypsum slurry permitted to flow through the outlets and into the
gypsum board forming plant. The control may be one or more slurry delivery mechanisms,

as described in aforementioned U.S. Patent No. 5,908,521, which have controlled variable
delivery speeds so that only the desired amount of gypsum slurry is pumped through the
outlets.
Referring again to Fig. 1, mixer 30 comprises a first slurry outlet 34, controllable by a
control device 36, that allows for the continuous flow of a slurry mixture having desirable
characteristics, as described in aforementioned U.S. Patent No. 5,908,521. In this
embodiment, mixer 30 is set to provide two types of slurry. Control device 36 delivers a
denser gypsum slurry mixture that is ultimately utilized adjacent the facing of the completed
gypsum board, as will be described below.
The end of the slurry outlet 34 extrudes the gypsum slurry directly onto the bottom-
facing sheet 14, which is continuously moving over the surface 18 of forming table 16.
Slurry outlet 34 preferably comprises a rubber boot, but other types of outlets may be used,
for example flexible hoses or piping. Preferably, the gypsum slurry 38 is poured onto the
upwardly facing surface of the sheet 14 at a position where it is supported by the forming
table surface 18, and a predetermined amount of dense gypsum slurry is deposited over the
continuously moving sheet 14 so as to coat the internal surface of bottom face sheet 14. It
should be noted that this upwardly facing internal surface of sheet 14 is normally destined to
be an inner surface of the bottom-facing sheet 14, and will be facing inwardly from the board
surface when the gypsum board is fully formed. To ensure that the dense gypsum slurry 38
is evenly spread out over the top surface of the bottom face sheet 14, a set of roller wheels
40,42, also referred to herein as roll coaters 40,42, are positioned again vertically over and
under the sheet 14. The wheels 40,42 can rotate in forward or reverse directions.
One advantage and benefit which derives from use of rotating roller wheels 40,42 is
that in addition to providing a smooth, evenly spread surface coating over the mat comprising
the bottom facing sheet 14, the dense slurry layer 38 deposited on the inner mat surface is
forced, by the top roller wheel 40, to extend through the sheet 14 and to form a structurally
integral surface. The surface layer of gypsum slurry 38 may be modified to include
additives, such as an engineered polymer, to provide structural strength and load carrying
capability to the gypsum board product. As will be described, the optional polymer additive
may also present a polymer matrix that provides a water impervious surface having desirable
performance characteristics, such as, plastic sheathing, or water repelling, properties so as to
expand the possible uses of the gypsum board products to both indoor and outdoor use.
In a preferred embodiment of the invention, the material comprising the bottom-
facing sheet 14 is a mat of randomly aligned mineral, e.g., glass, fibers, having an average

fiber diameter of 13-16 µm (.005-.0065 inches), and including a binder to hold the glass fibers
in the form of a glass fiber mat having a desirable thickness. Such glass fiber mats are
known for use in the production of gypsum board, for example, see aforementioned U.S.
Patent No. 6,524,679, No. 4,378,405 and WIPO Publication No. WO9809033 (European
Patent No. EP 0 922 146). Use of a mineral fiber mat, which is porous to water generally,
provides added structural strength to the gypsum board. The porous nature of the mineral
fiber mat also permits gypsum slurry to penetrate through the pores between the mineral
fibers and to permeate so as to cover both the top surface and through slurry penetrating the
bottom surface of bottom facing sheet 14 because of slurry penetration. Thus, as the bottom
facing sheet 14 passes through the roll coaters 40, 42, the unset higher density gypsum 38 is
coated over the mineral fibers and is forced in the roll coating process to penetrate through
the bottom facing sheet 14 and coat each of its top and bottom surfaces with an unset denser
gypsum layer 38. Ideally, the high-density gypsum 38 is forced to penetrate 100% through
the glass mat sheet 14, although manufacturing tolerances may permit penetration of
approximately 95-98%.
In a preferred form, the roll coaters 40, 42 cause penetration of the unset denser
gypsum slurry 38 to coat the bottom surface of the glass mat bottom sheet 14. This bottom
surface of the bottom-facing sheet 14 will ultimately become the facing surface of the
completed gypsum board products. Preferably, the unset gypsum slurry 38 is caused to form
a dam 39, which then impregnates a continuous layer of unset gypsum through to the bottom
surface of the glass mat 14 to form a dense slurry gypsum layer having a thickness that is in a
range from approximately 0.01 to 2.0 mm, as measured from the outermost surface of glass
mat 14. Although penetration of the slurry 38 may not result in a continuous layer having a
discrete thickness, nevertheless the process preferably will result in each of the glass fibers,
comprising the glass fiber mat 14, in being coated on its surface so that very few or no
exposed uncoated glass fibers remain.
The speed of rotation of the rollers 40,42 may be adjustable depending on the
viscosity of the density of gypsum slurry 38, the speed of linear travel of the glass fiber mat
14 and the amount of the gypsum slurry 38 to be applied to the mat 14. In effect, the roll
coaters 40, 42 serve to deliver the slurry 38 through the small random openings between
fibers of mat 14 and deposit the material on the top of the fabric web in greater or lesser
amounts, as desired, filling the openings and coating both the bottom face as well as the top
face of mat 14.

Although the roll coaters 40,42 are shown rotating in the direction of travel of the
bottom facing sheet 14, it is possible, and in some embodiments of this invention, desirable
to have the roll coaters rotate in the opposite direction from that shown in Fig. 1. In such
case, a mechanism such as a forming belt line/disposed downstream of the roll coaters 40,
42, described below, is utilized to provide a motive force for pulling the bottom facing sheet
14 through the gypsum board forming station 10, even against the reactive forces produced
by counter-rotating coater rolls. Of course, alternatively, other means may be utilized at
different locations in the processing production line to provide the motive force for moving
the sheet 14 through the station 10, for example, another set of rollers downstream (not
shown) that pull the mat 14 toward the right. It should be noted that the gypsum slurry layer
on the top surface of bottom facing sheet need not be absolutely level or completely even
since subsequent steps in the process may provide additional smoothing opportunities, as will
be described below.
Gypsum board with mineral fiber facing sheets may be produced in multiple layers,
including, but not limited to, a strong, more dense upper and lower surface layers and a less
strong and less dense middle layer or core. The layered structure is advantageous as it allows
the gypsum board to have a reduced weight, without sacrificing the composite structural
strength of the final gypsum board product. Thus, and in accordance with the teachings of
aforementioned U.S. Patent No. 5,908,521, the continuous mixer 30 is configured to provide
a second, less dense gypsum slurry, referred to as core gypsum slurry 44 or simply slurry 44,
which comprises the bulk of the material in the finished gypsum board products. The core
gypsum slurry 44 is pumped out of the mixer 30 by a control device 46 and through an outlet
48, which may comprising a rubber boot or hose. A continuous layer of the unset slurry 44 is
caused to form onto the laterally moving combination bottom facing sheet 14 and layer of
dense slurry 38.
The core slurry 44 may comprise a different composition of constituent material than
the dense gypsum slurry 38, for example by the addition of filler or strengthening additives,
as is known, or may simply comprise the same constituent elements but may have a lighter or
less dense consistency because the gypsum slurry 44 contains foaming materials therein,
which are not added to the dense slurry 38. It is known that a longer mixing time for the
unset gypsum causes more of the entrained air bubbles, sometimes referred to as foaming, to
reach the surface of the unset gypsum and thus to be removed from the unset gypsum slurry
material. It is the greater amount of air, entrained as miniscule air bubbles, which gives rise
to the lighter, less dense core gypsum slurry 44.

Gypsum slurry, and especially gypsum slurry that has been modified with polymer
additives, has adhesive characteristics in its wet state that present some difficulty in handling.
Accordingly, a film coating 43 is preferably provided on at least one of the roll coaters,
preferably roll coater 42, which allows for easier continuous separation of the coater wheel
surface from the surface of the wet gypsum surface while simultaneously depositing the
majority of the gypsum slurry 38 on the mat of sheet 14. Materials for such a film coating
surface include appropriate polymers, such as a Teflon® coating, that are capable of
providing a firm surface yet avoiding gypsum slurry adhering or clinging to the surface of the
roll coater wheels.
Another important reason for providing a denser slurry layer, in conjunction with a
lighter core slurry layer in the gypsum board, is that the boundary between the dense slurry
layers 38, and the core slurry layer 44 provides an inhibiting barrier that serves to control and
inhibit the migration of the polymer additives from the surface dense slurry layer 38 to the
core slurry layer 44. This migration is most likely to occur during the conventional heat
rendering process, described below, used for drying the finished board product. The
resulting board product is rendered better equipped to retain the polymer additives in the
surface dense slurry layer 38, which thus form a better, more uniform polymer matrix base or
"root system" for co-polymer formation with finishing products, as is described below.
As the dense gypsum layer 38 dries and cures, the polymer additives entrained therein
migrate toward and through the underlying fiber facing sheet 14 and the migration may
extend into the core slurry layer 44 in the form of tendrils or roots that provide for a greater
integrity in the bond formed between the core gypsum layer 44, the fiber sheet 14 and the
overlying dense slurry layer 38. Moreover, because the lighter gypsum layer 44 includes an
entrained foam, and the dense slurry layer 38 does not, the penetration of the additive
materials is deeper into the layer 44. This bonding produced by the impregnated additive
polymeric material improves matrix formation, ultimately improving the surface hardness
and structural integrity of the finished gypsum board, and provides a strong outer shell to the
board and also improves the load bearing capacity, contributing to its flexibility.
Referring again to Fig. 1, after passing through the roll coaters 40, 42, the bottom
facing sheet 14 passes onto a second forming table 50 having a horizontal forming surface
52. Although the first forming table 16 and second forming table 50 are shown as separate
tables in the diagrammatic rendition of Fig. 1, it is possible and in certain cases preferable,
that the forming table comprises one elongated table (not shown) with several cutout portions

within which, for example, the creaser wheel assembly 20, or the roll coaters 40, 42 and
vibrators, are mounted.
To facilitate the transport of the bottom-facing sheet 14, including the weight of the
dense slurry 38 and core slurry 44, a non-stick table deck 59 is disposed over the surface 52
of table 50. Referring now to Fig. 2, which is a detailed view of Fig. 1, an upwardly facing
surface 60 of table deck 59 provides a working surface for the production of gypsum board.
Preferably, the table cover comprises a smooth, non-stick material, such as stainless steel, an
elastomeric material, e.g., rubber, or a polymeric material, e.g., Formica®, and is of sufficient
structural strength to support the moving weight of the slurry 44 deposited on the table 50.
As is evident in the detailed cross-sectional view of Fig. 2, the table deck 59 rests
directly on surface 52 of table 50, so that as the core slurry 44 is deposited on the bottom
facing sheet 14, the weight of the slurry 44 places downward pressure on the sheet 14,
resulting in flattening of the under surface of the sheet 14 against the surface of the table deck
59. However, because of the smooth, non-stick characteristics of the table deck 59, the bottom
facing sheet 14 and slurry 38, 44, freely traverse over the forming tables, as described below.
The cross-sectional view of Fig. 1 also does not show the width of the outlet spouts 34
and 48. Various known configurations may be utilized, including an elongated spout that is
disposed transversely to the direction of board travel. Such spouts may output a sheet of
gypsum slurry across the width of the mat 14. Alternatively, a tubular spout attached to a
rubber boot (as shown) deposits a continuous stream of gypsum slurry onto the glass fiber
sheet 14. That gypsum slurry stream may then be spread out, before reaching the roll coaters
40,42, to provide a smooth surface over the sheet 14 by, for example, diagonally angled vanes
(not shown) or by specially constructed rollers or a dam that spread the gypsum slurry from the
center toward the edges of bottom sheet 14. The exact shape of the spouts is not considered to
be critical to this invention, as long as the function is achieved of evenly spreading the gypsum
slurry over the entire width of the mat of both the bottom and top sheets.
The unset, less dense core gypsum slurry 44 is deposited on the penetrated bottom
facing sheet 14 at or adjacent a third forming table 56, having a top surface 58, for supporting
the combination of penetrated mat 14 and slurry 44. An opening 62 between the second
forming table 50 and third forming table 56 provides a space for disposing a first deck vibrator
64, and another opening 66 provides for mounting a second deck vibrator 68 between the third
forming table 56 and a fourth forming table 70, having a top surface 72. Such vibrators are
described in U.S. Patent No. 4,477,300, which is incorporated by reference herein.

As shown more clearly in the detailed view of Fig. 2, the table deck 59 extends
between the first and second forming tables 50,56 over the opening 62, and also between the
third and fourth forming tables 56, 70 over the opening 66. Because each of the tables 50, 58,
70 are disposed so that their surfaces 52, 58,72 are coplanar, the table deck 59 mounted onto
the table is vertically fully supported across essentially the full length of the gypsum board
forming station 10, i.e., across the full length defined by second to fourth forming tables 50,
56,70.
Shown in Fig. 2, deck vibrators 64,68 each comprise rolls 74, which are mounted
immediately adjacent sections of the table deck 59 covering the upper portion of the
respective openings 62, 66. Each of the deck vibrator rolls 74 are mounted to rotate around
axles 76, both extending horizontally in a direction transversely to the direction of travel of
the board production line. Each of the rolls 74 has a diameter that is just slightly less than the
radial distance between each axis 76 and the bottom surface 62', 66' of the table deck 59
covering the respective openings 62, 66.
Each deck vibrator 64,68 further comprises a plurality of bumps 78 which extend
radially beyond the outer surface 79 of the deck vibrator rolls 74. Bumps 78 extend
longitudinally along the surface 79 of the rolls 74 in a direction parallel to the axis 76. As the
deck vibrator rolls 74 rotate about axis 76, the bumps 78 routinely strike the underside
surfaces 62', 66' of the table deck 59, which momentarily lifts the table deck 59, together
therewith the bottom facing sheet 14 and slurry 38,44, combination, which agitates the slurry
resting on sheet 14. Such agitation causes the slurry 38 to even out over the upper surface of
the penetrated mat 14 and also causes the slurry 44 to more completely permeate through and
bond with the denser slurry 38 located on the upper surface of the bottom facing sheet 14.
Another feature provided by the deck vibrators 64,68, is the "kneading out" of larger
entrapped foam air bubbles from the bottom surface of the bottom facing sheet 14. As the
bottom-facing sheet 14 passes over the openings 62, 66, the denser slurry 38, which has
penetrated through the mat of bottom facing sheet 14, is still unset and continues to have
entrained air bubbles within the gypsum slurry and adjacent bottom sheet surface. Vibration
from the deck vibrators 64, 68, causes these foam bubbles to reach the surface and exit from
within the penetrated gypsum slurry 38, thus resulting in a smooth outer surface of the
completed gypsum board when the manufacturing process is completed, as in
aforementioned U.S. Patent No. 4,477,300.
Completion of the smoothing operation of the slurry 44, resulting in an essentially
planar combined bottom facing sheet 14 and core slurry 44 is further facilitated by a forming

plate in the top and bottom sheet joining station 80 (Fig. 1), disposed downstream, i.e.,
toward the right as seen in Fig. 1, of the deck vibrators 64, 68. The forming plate assembly
of sheet joining station 80 operates in conjunction with a top facing sheet 114 formed by the
sheet coating station sub-assembly 110 having similar elements to those in the main
production line that form the bottom-facing sheet 14.
Top-facing sheet 114 is comprised of a sheet or mat of randomly aligned mineral
fibers, such as glass fibers, and is unrolled from a supply roll 112, similar to the supply roll
12. Similar elements to those used for the production of bottom facing sheet 14 are identified
by like numerals in the 100 series, utilizing the same two last digits as those identifying the
like elements in the production of the bottom sheet 14. Supply roll 112 pays out a continuous
top facing sheet 114, which, in the completed gypsum board, will be adjacent the inner facing
surface of the gypsum board product subsequently used in wall construction.
As shown in Fig. 1, the top facing sheet 114 may require feeding through various
loops around, for example, rollers 102, so as to avoid interference of the main production line
by the operation of top sheet sub-assembly 110. Top sheet sub-assembly 110 directs the top
facing sheet 114 over a top sheet forming table 116 having an upwardly facing surface 118.
The continuous mixer 30 further comprises a slurry outlet 134 being controllable by a
control device 136 providing a continuous stream of denser gypsum slurry 138 to the sub-
assembly 110 for deposit onto the top facing sheet 114, as shown. A detailed cross-sectional
view of the top sheet production station portion of sub-assembly 110 is illustrated in Fig. 3,
and reference is now jointly made to Figs. 1 and 3. Although in Fig. 1, the preferred
embodiment of two separate slurry controllers 36, 136 are shown for supplying two different
slurry mixtures 38, 138, for respectively, the bottom facing sheet 14 and the top sheet 114, it
may be desirable to have one mixer discharge leading to dual controllers for controlling the
discharge of two or more outlets, similar to that described in aforementioned U.S. Patent No.
5,714,032. Alternatively, a single controller (not shown) may be used with the discharge
outlets having individual valves enabling variable flow of gypsum slurry that is controllable
for each outlet spout depending on the operational needs of the board production process.
Shown in Fig. 1, are separate controllers 36,46,136, each for controlling the output
of a single outlet, i.e., dense gypsum slurry outlets 34,134, or core slurry outlet 48. The
configuration of the continuous mixer 30 provides separate mixing chambers, each attached
to, and feeding gypsum slurry to, a separate outlet, which provides a specific type of gypsum
slurry, as needed. Customization of the slurry provided to each of the outlets 34,48,134
thus enable a gypsum board line operator to provide different slurries, having desirable

characteristics, to the location in the manufacturing line where needed. For example, an
outlet, such as outlet 34, may be required to provide a denser gypsum slurry, such as slurry
38. The slurry may be desired to include specified additives, for example, a polymeric
compound, which forms a matrix with the set gypsum after it sets, so as to provide a suitable
surface for further finishing, as will be described below. However, if it is only necessary for
the front facing surface to have such a surface, then using the embodiment shown in Fig. 1
provides the option to include the additive in only the dense gypsum slurry 38, pumped from
controller 36, but not to include such an additive in the slurry 138, which will end up on the
inner, back side of the gypsum board during construction. Alternatively, the gypsum slurry
138 is denser than the core slurry 44, and may have an identical consistency as that of the
slurry 38 coating the bottom facing sheet 14.
Referring again to Figs. 1 and 3 showing the top sheet slurry coating station 110, the
dense gypsum 138 is deposited on the top facing sheet 114, comprised of a mat of glass
fibers, which is moving in the direction shown by arrow A, past the surface of the top sheet
slurry table 116. The top sheet is moving essentially at the same rate as that of the bottom
facing sheet 14 traveling over forming table 16. The gypsum slurry 138 is denser than the
core slurry 44, and may have an identical consistency as that of the slurry 38 coating the
bottom-facing sheet 14.
The top facing sheet slurry coating station 110 comprises a short forming plate 116,
similar to the forming table 16, with the exception that the linear dimension of plate 116 is
much shorter, having a sufficient length to achieve deposition of the gypsum slurry 138 and
to spread out the slurry over the surface of the moving top facing sheet 114 between the
lateral edges of the continuous sheet 114. To assist in the process of spreading the gypsum
slurry 138 over the surface of sheet 114, one or more pneumatic table vibrators, such as
vibrator 148, may be included to vibrate the surface 118 of the table 116.
Applicator wheel 140, having a cylindrical surface 142, rotates about an axle 144,
which axle 144 extends transversely to the direction of travel of the sheet 114. The vertical and
horizontal disposition of axle 144 is important in obtaining the desired result of sheet 114 being
fully impregnated with the dense slurry 138. As shown in Fig. 3, axle 144 is disposed linearly
at a very short distance past the edge 117 of table 116. The axle is vertically disposed just
slightly less than the radius of wheel 140 above the table surface 118 so that the applicator
wheel 140 extends into the space under the plane defined by the table surface 118. As is shown
in Fig. 3, during production the applicator wheel 140 puts downward pressure on top facing

sheet 114, which sheet is deflected some slight distance from its linear path followed across the
table surface 118.
The dense gypsum slurry 138 being deposited on the moving top facing sheet 114'
produces a slurry concentration at a dam 139, comprised of excess dense slurry 138, which
collects in the constricted space between the applicator wheel 140 and the top facing sheet
114. The size of dam 139 can vary, depending on the desired characteristics of the resulting
impregnated top facing sheet 114' that is produced by the top sheet coating station 110. For
example, if a greater degree of coating is desired to provide greater structural strength of the
gypsum board, then the size of the dam 139 may be adjusted so that a greater amount of
dense gypsum slurry is impregnated into the interstices between the mineral fibers of the mat
comprising top facing sheet 114. For purposes of distinction, top facing sheet 114 is
designated as impregnated top facing sheet 114' after impregnation by the dense slurry 138.
Working in conjunction with the applicator wheel 140 is downwardly curved
transversely extending directional plate 113, upon which the sheet 114 impinges as it exits
from contact with the applicator wheel 140. The directional plate 113 is preferably mounted
so that the apex 115 is adjacent or within the plane defined by the surface 118. This
positioning causes the sheet 114 to be placed into tension as the applicator wheel 140 pushes
the sheet 114 downwardly from the plane, which disposition assists in the penetration of the
gypsum slurry 138 through the mat of sheet 114. To inhibit the formation of slurry 138 on
the surface 142 of applicator wheel 140, an appropriate thin film coating 143, comprising, for
example, a Teflon® coating, may be optionally disposed on the surface of wheel 140, similar
to the coating 43 of roll coater 42 described above.
The top sheet 114', impregnated with the dense gypsum slurry 138, is directed from
the applicator wheel 140 to a second roller wheel, the transition roller wheel 104, having an
axle 144' that is parallel to axle 144. The transition roller wheel 104 is in the general path
and in the plane defined by the surface 118, and its function is to change the direction of
travel of the top facing sheet 114' so as to render the top surface of the sheet to become the
bottom surface, and vice versa. That is, the surface of the top facing sheet 114 that was on
the bottom adjacent the surface 118, becomes the top surface and the sheet 114' is ready for
delivery to and joining over the core slurry 44, as is described below.
The sheets 114,114' are joined at a sheet joining station 80 (Fig. 1) that is described in
more detail in aforementioned U.S. Patent No. 6,524,679, and the remainder of the discussion
in that patent relating to the board forming structure and methods will be omitted herefrom for
brevity.

The features that are significant to the present invention relate to the mixer 30 and the
dispersion of the additives onto one or both of the mats 14,114 before they are assembled at
the gypsum board forming station. As shown in Fig. 1, and described in the parent U.S. Patent
No. 6,524,679, the dense slurry layers 38,138 which are deposited onto the mats 14,114
before they are joined with the core slurry layers 44, are first deposited on one or more
specified locations on the mats 14, 114 and then are dispersed across the width of the mats 14,
114 by the rollers to provide a uniformly thick film of dense slurry before they are joined at the
sheet joining station 80. This even layer of dense gypsum is for the most part evenly
distributed and for most additives, the distribution of the additives within the dense slurry 38,
138 is also evenly distributed across the mats 14 or 114 by virtue of the dispersion of the
additive within the dense slurry layer when it is mixed into the dense slurry at controllers 36 or
136. However, for certain types of additives, for example, hydrophobic additives, it has been
found that the mixture into the dense slurry is not always even, but may result in clumps or
uneven dispersion of the hydrophobic additives throughout the dense slurry layer. As a result,
when the dense slurry is dispersed over the mats 14,144, the film of dense slurry may be
evenly and consistently spread out over the surface of the mat, but the additive itself may be
clustered, either randomly or periodically, on the mat. Such as eventuality is undesirable, since
uneven dispersion of the additive on the surface of the gypsum board products often result in
the additive working poorly or inadequately to perform the function for which it was added.
For example, one additive that was found to experience inconsistent dispersion over the
board surface was a wax emulsion. The wax emulsion was added to provide desirable
characteristics to the board surface, for example, to enhance water resistance at the board
surface. However, as is generally well known, water will seek to penetrate into a surface and
will first succeed to do so at a point of least resistance. Thus, water seepage into the core of a
board was facilitated by the uneven dispersion of the way emulsion, and the boards were found
to not meet the exacting standards of water resistance that were required in certain jurisdictions.
Thus, the features of the present invention were developed to provide for more even dispersion
of additives, and especially hydrophobic additives, into the dense gypsum slurry and thus to
provide a consistently more even dispersion of the additive over the complete width profile of
the board.
Referring now to Fig. 4, in which similar elements are identified by the identical
reference numbers, the mixer 30 is shown in a schematic diagram illustrating the additive
delivery system. Mixer 30 may take the form of any of a number of mixer types, but in this
instance, the mixer 30 preferably is a pin mixer 30 known in the art. The pin mixer 30 is the

general mixer for all slurry for both the dense slurry layer and the core slurry layers. As
described above, the core slurry 44 is taken directly from the mixer 30 through the controller
46. However, the controller 36 controls the dense slurry 38 as it is siphoned from the pin mixer
30. The pin mixer 30 has an inlet aperture 186 connected to an additive feed pipe 188 that
feeds directly into the dense slurry outlet 34. The pipe 188 is used for delivery of dense slurry
38 to one or both of mats 14, 114 onto which dense slurry 38 or 138, having the appropriate
additives, is desired. Thus, the additive feed pipe 188 is capable of introducing an additive
directly into the slurry stream as it passes through the dense slurry outlet 34.
Although shown being connected to only the one dense slurry outlet 34, it should be
understood that another pipe, similar to pipe 188, may also be attached to other outlets, either
of the dense gypsum slurry, for example, outlet 134, or even to the core gypsum slurry outlet
148, if that is found desirable. The described structure is not to be limited to the single
connection shown, but a feature of the invention is the capability of targeting specified
additives to that gypsum layer where they are desired. Other modifications will also become
apparent to a person having ordinary skill, for example, connecting the additive feed pipe 188
directly to the controller 36 or 136, where the desired additives are mixed into the dense
gypsum slurry stream as other controls and processes are simultaneously occurring.
Referring again to Fig. 4, the additive provided for mixing into the gypsum slurry
streams is contained in an additive reservoir 192. Because the construction described herein is
especially well suited for even dispersion of wax additive, for providing the desirable water
absorption resistance at the surface of the gypsum board. The reservoir 192 contains wax, and
it may require a preheating arrangement and a method of emulsifying the wax into an emulsion
that can be easily dispersed in an aqueous slurry. The reservoir 192 schematically is shown
being separated from the injection port 186, but it may be patentable to provide the reservoir
closer to the pin mixer 30, of physically possible, to maintain the wax in the emulsified
condition prior to delivery.
A transfer pipe 194 is connected at one end to the wax emulsion reservoir 192, which
provides a continuous stream of wax emulsion to the injection port 186, as needed. Filtration
of the wax emulsion may be required, and a filter (not shown) may be disposed in the transfer
pipe 192 to avoid excessively large wax solids from entering the wax emulsion stream to avoid
plugging or clogging the delivery system, as will be described below.
The transfer pipe 192 is connected at the other end to a pump 198 that may include a
flow control for regulating the rotation of the pump 198, or as a separate flow control valve 196
disposed in-line in either the transfer pipe 194 or the additive feed pipe 188, so as to control the

rate of flow of the wax emulsion additive to the injection port 186. The wax emulsion rate flow
control is a significant feature of the present invention, as very low flow rates are required for
the additive, so as to maintain the desirable homogeneous consistency and constituent ratio of
the dense gypsum slurry to additive. This permits the invention to achieve the optimum
balance between reducing the cost of unnecessary additive, while also simultaneously
providing a homogeneously applied water resistance, that is, consistently reducing the surface
absorption characteristics, across the compete lateral surface of the board.
To achieve the desired purposes, another significant feature is provide at the injection
port 186, that mixes the additive into the dense gypsum slurry as it is transferred from the pin
mixer 30 to the top and bottom slurry coating stations 110,18, respectively. Thus, there is
provided an additive delivery system 200, disposed in-line at the additive injection port 186
within the end of the additive feed pipe 188 that is attached to and feeds the dense slurry outlet
34. An added impetus beyond gravitational forces for transferring the additive from the
reservoir 192 to the additive delivery system 200 is shown schematically in Fig. 4, and
comprises a pump 198, that may be a positive displacement pump, an air diaphragm pump, or
other appropriate pumping mechanism. Other appropriate pumps comprise a MOYNO pump,
available from Moyno, Inc., of Springfield, Ohio or a TRIPLEX pump, available from Kerr
Pumps, of Sulphur, Oklahoma. The positive displacement is necessary to maintain a positive
pressure on the additive stream to make it available at the additive delivery system 200, when
and as needed. These types of positive displacement pumps are preferable because they avoid
shearing of the emulsion, and so maintain the emulsion in the desired state.
Referring now to Fig. 5, two additive delivery systems 200 are each connected to an
additive feed pipe 34 at separate additive injection ports 186. Although two additive delivery
systems 200 are shown, any number from one to twenty such systems may be utilized,
depending on the amount and types of additives that is desired to be added to the slurry stream
in pipe 34. Each of the systems 200 includes a quick connect coupling 202 to enable the quick
connection to an input additive feed pipe, such as pipe 188 shown in Fig. 4. The quick connect
coupling 202 is prefabricated and is attached to the system 200 and may include a quick
connect hut 204 that provides a sealed fluid communication to the pipe 188 upon a simple
tightening of nut 204.
This arrangement provides for several advantages, including that of selective and easy
attachment of the appropriate additive delivery system 200 to the dense gypsum slurry stream,
depending on the type and characteristics of the board desired for manufacture. Alternatively,
and in view of the below described construction of the system 200, it may be appropriate to

connect two or more systems 200 to the same feed pipe (not shown), thereby delivering twice
the amount of slowly injected additive into the slurry stream. This alternative procedure may
be utilized to avoid excessive flow rate that would flow through a single system 200, and would
also ensure more complete mixing of the additive in the gypsum slurry.
As shown in Figs. 1,4 and 5 first gypsum slurry outlet pipe 34, connected to the pin
mixer 30, and extends in an outward direction therefrom. After being discharged from the
controller 36, it is connected to a first input pipe 208 that may be utilized as an extractor for
dense slurry from the slurry stream, in the event such slurry is desired, for example, for testing
or quality control, or if necessary for some other process in the manufacture of the gypsum
board panels.
Downstream along pipe 34 a diaphragm pinch valve assembly 210, comprising a
connecting joint 212 connecting to the pipe 34 at one end, a diaphragm pinch valve 214 at the
other end, and a central section 216, to which an air supply port 218 for the diaphragm pinch
valve 214 is connected. The diaphragm valve 214 is pneumatically driven by the air supply
and can control flow rate of the dense gypsum slurry as it passes through pipe 34.
Immediately downstream of the diaphragm pinch valve assembly 210 there are disposed
the two additive delivery systems 200, but fewer or more of these systems 200 may be
connected to the pipe 34. Although, the preferable configuration of downwardly flowing
systems 200 are shown, in order to be assisted by gravity flow of the additive, it is
contemplated that this orientation may be changed to conserve space, and the systems may be
disposed at an angle to the vertical or even underneath the pipe 34.
The wax emulsion additive providing in the reservoir 192 (Fig. 4) may be any of a
variety of waxes capable of providing water resistance to the surface, for example, one or more
of a paraffin wax emulsion or other known and commercially available materials capable of
providing water resistance characteristics. Furthermore, although described above in terms of
the use of these additives with a fiber mat faced gypsum board, the present invention may also
be used together with standard paper faced gypsum to increase the water resistance
characteristics at the gypsum paper surface interfaces of such boards, or other types of
cementitious boards in which targeted delivery may enhance the value of the products. Other
additives that can be utilized in this method for both the types of panels described in
aforementioned U.S. Patent No. 6,524,679 and for paper face products and any combination of
cementitious and paper to improve or enhance other properties are as follows: polymers, boric
acid, borates, other intumescence-like additives, surfactants, dispersants, retarders, potash,

silicates, starches, phosphates, perlite, alumina and any material that can be solubilized or
dispersed in a liquid media may be used.
Referring now to Figs. 6 and 7, perspective views, respectively, of a ready to deploy
and of a deployed additive delivery system 200, shown in alternative embodiments. As shown
in Fig. 6, system 200 includes the quick connect nut 204 for connecting additive feed pipe 188
to the additive inlet port 186. With this quick connect, a user may easily exchange pipes for
providing other alternative additives, as desired, for injection into the dense slurry stream.
For example, a wax emulsion additive has been described above. However, other
chemical additives may be desired to be added by targeting only one of the layers of gypsum.
Also physical additives may also be added for providing other desirable characteristics, for
example to the dense slurry layers. One such exemplary additive may comprise the targeting of
microfiber to the stratified dense slurry layer for providing enhanced structural strength to the
outer layers of the finished gypsum board product. Alternatively, the microfibers may be
introduced to both the dense and core gypsum layers, but in different concentrations, e.g., more
concentrated mixture of microfibers may be added to the dense slurry layer and a less dense
concentration may be added to the core gypsum, utilizing the teachings and structural features
of the present invention.
The microfibers may comprise any of a number of different materials, for example, e-
glass, carbon, mineral fiber, polymeric and/or metallic fibers and the concentrations may be
varied, depending on the specific characteristics of the gypsum layers that are desired. An
appropriate range of concentration of such microfibers may be between 0.1% to 5.0% by
volume. The microfibers may have lengths of from between 1.0 and 25.0 mm, widths of
between 0.002 and 0.025 mm and an aspect ratio of between 1:1 and 25:1, depending on
requirements.
Referring again to the system 200 shown in Figs. 6 and 7, once the quick connect
coupling nut 204 is tightened on to the system 200, there s a sealed flow of the additive
materials, for example, a wax emulsion, through the system 200 and into gypsum slurry pipe
2\34. The system 200 thus includes structural features that control the consistency and
dispersion of the additives within the slurry stream passing through pipe 34, as described
above.
Additive delivery system 200 comprises an enclosing housing 206 that is shown as a
rounded conical housing having a large diameter opening 208 and a small diameter opening
208 and a small diameter opening 209. The small diameter opening 209 is connected by the
quick connect pipe 204 to the additive feed pipe 188, and provides fluid communication so that

the additive may flow through the housing 206 toward the inlet port 186. Although shown as
having conical shape, the housing 206 may take any type of shape commensurate with
maintaining the flow of additive into the slurry stream 38 in pipe 34, for example, an oblong
bow or an octagonal enclosure.
Housed within the enclosing housing 206 is a turbulator 220 that extends beyond the
large diameter opening 208 in a longitudinal direction, as shown. The turbulator is fixed as
shown in Fig. 6. It should be noted that Figs. 6 and 7 drawing may not necessarily be,to
scale. The turbulator 220 is a feature of the invention that assists in homogeneous blending
at the injection point of the additive into the slurry stream. The additive feed system 200
includes two insertion/retraction handles 222 that provide the controls for the longitudinal
position of the turbulator 220, so that when in the undeployed position as shown in Fig. 7, the
handles extend radially outwardly to disconnect the turbulator 220 from the receiving neck
234. Pulling the handles 222 toward the housing 206, as shown in Fig. 6, locks the
turbulator 220 in a direction away from the smaller diameter opening 210, and when
connected within the system 200, toward the additive injection port 186. Pulling said handles
in locks the coupling into position, connecting the housing 206 to receiving neck 234. In this
position, tubular constrictor valve 224, injector nozzle 226, and additive outlet opening 228
extend into receiving neck 234 and position the turbulator 220 for desired delivery of
additives. The turbulator 220 comprises a tubular constrictor valve 224, which is attached to
an injector nozzle 226, having an additive outlet opening 228 at the distal end thereof. The
inner diameter of the injector nozzle 226 may be in a range of from about 3/32 to about 3/16
of an inch (2.38 to 4.75 mm), and preferably is about 1/8 of an inch (3.17 mm) in diameter at
the opening 228. The additive outlet opening preferably has an internal opening diameter
that is much smaller than that of the injector nozzle, and may be in a range of from about 3/32
to about 1/16 of an inch (2.38 to 1.59 mm)
The above-described configuration provides egress of wax emulsion solids at an
appropriate flow rate into the dense slurry layer of between 1 lbs./Msf to about 10 lbs./Msf
where Msf is one thousand square feet. The turbulator delivery pattern, that is, the spray of
additive that is delivered to the dense gypsum slurry 38 may comprise one or more known
patterns that can provide the maximum dispersion of the additive material within the slurry
stream, for example, a flat, conical multiple linear injection, or other appropriate geometrical
pattern capable of injecting the additive materials deep into the slurry stream so as to
effectively mix then thereinto. Thus, although shown having a cylindrical delivery tip in Fig.
7, the delivery tip and additive injection opening 228 may take other forms to provide a

different delivery pattern and thereby to achieve optimal additive homogenization in the
slurry stream.
The angle of injection also provides a variable additive injection parameter that can be
optimized for obtaining maximum additive penetration and homogeneity of additive in the
slurry stream.
That is, while the angle shown in Fig. 7 is directly perpendicular to the plane of the
end opening 208 of the housing 206, other injection angles can be used as well, and may take
on either an acute angle relative to the direction of slurry flow, and may be either angled with
or against the flow in a range of from about 1° to about 179° relative to the direction of flow.
Optimally, the angle is very close to perpendicular as shown, but practical adjustments in a
range of from about 70° to about 110° possibly provide desired mixing effects of the additive
materials as these are delivered into the slurry stream. For example, an angle which injects
the additive into the stream at an angle against the flow of the fluid stream so that the mixing
occurs more vigorously. However, this may not be desirable in some instances, for example,
if it is not desirable to inject the additive material counter to the slurry stream so as to avoid
excessive agitation or to avoid disturbing the slurry flow. In such a case, it may be preferred
to angle the additive injection direction with the flow of the slurry stream and have the
additive be mixed into the slurry by natural agitation during delivery and spending of the
dense slurry 38 over the mats 14,114 or alternatively, over paper facing.
The turbulator 220 has not been generally utilized for providing additive injection into
the slurry of a gypsum board line during the manufacturing process of gypsum board. Thus,
although such turbulator nozzles are available commercially, for example, from Spraying
Systems, Co. of Wheaton, Illinois, available as Part No. 1/8HH-SS8W, these types of
turbulators have not been made nor used for dispersion of additives directly into a flowing
slurry stream. The aforementioned U.S. Patent No. 4,378,405 to Pilgrim, for example,
teaches a surface modifying additive such as water-proofing agents, in the form of synthetic
resins, to be sprayed onto the glass mat fabric or web, but this suggestion does not necessarily
result in the desired additive on the surface of the gypsum board product, especially if the mat
is essentially encased in the gypsum, as is taught in the aforementioned parent U.S. Patent
No. 6,524,679. Others teach the dispersion of the additive in the core gypsum slurry as well
as the surface layers in equal propositions, thus failing to provide the targeted additive
delivery to specific layers.
As an example of the targeted delivery of the wax emulsion additive described above,
it has been found that mixing a first batch of additive to the gypsum slurry mixture in pin

mixer 30 in the ration of, for example, 60 lbs./Msf Additive wax emulsion per batch of slurry
mixture, and adding 5 lbs. Additional wax emulsion directly to the dense slurry mixtures 38,
138 at the pipes 34,134, as described above, will result in lesser water resistance
characteristics in the core layer, but in much greater water resistance in the two surface layers
of gypsum that encase the fiber mats 14,114, because of the smaller proportion of dense
slurry to core slurry that is delivered to the gypsum board line. This results in a product that
is lighter in weight, and is significantly better able to repel water or moisture from the surface
layers, where this property is most needed, than is a standard, non-targeted process that
would utilize additive in the amount of 70 lbs. Per batch evenly spread across all three layers.
Referring again to Figs. 6 and 7, the configuration shown provides for the tip 2 of
nozzle 226, including additive outlet opening 228, to be flush with the inside wall of the pipe
34, In this way, the turbulator 220 does not disturb the slurry stream, but nevertheless injects
the additive (wax emulsion) into the slurry 38 as it is transported therethrough. Because of
the continual fluid pressure provided by the pump 198, a vortex of additive wax emulsion is
produced in the slurry stream which ensures more even mixing. Moreover, use of a positive
displacement pump, so as to avoid pulsations in the additive delivery, produces more even
mixing results.
However, the position of the nozzle tip may also be more actively disposed to extend
beyond the inner surface of the wall of the pipe 34, and the additive outlet opening 228 is
disposed in the slurry stream and so to inject the additive more forcefully into slurry mix to
obtain a more robust mixing. However, care must be taken to avoid damage to the nozzle
226, since the gypsum slurry is being transported very rapidly through the pipe 34. This
configuration may be used together with the angled nozzle, described above, in which the
nozzle tip is angled at an acute angle with the flow of the gypsum slurry, so as to minimize
the risk of damage.
The quick connect coupling 210 is attached at the narrowed 209 of the housing 206 to
the nut 204, and at the distal larger end 208 to the receiving neck 234, shown as a hexagonal
housing, but capable of being almost any geometrical shape. When attaching the additive
delivery system 200, care must be taken so that the nozzle 226 is not damaged. Once the
housing 206 is in place and engaged with the receiving neck 234, the handles 222 are rotated
in the upward direction, which locks the system in place. Simultaneously, the locking action
of the handles 222 also extends the nozzle 226 downwardly toward the pipe 34 until the
nozzle additive output opening 228 is flush with the inner wall surface of the pipe 34. The
port 186 is enclosed by a port enclosure 236 that is connected onto the pipe to hermetically

seal the port 186, preferably by welding or other appropriate means. An optional nut 238,
and a transitional pipe connector 239 are shown in Fig. 6, but these are not necessary if a
dedicated additive port 186 is provided in the gypsum board line.
Additional modifications are also possiblein the event that a dedicated additive outlet
port 186 is provided. For example, vanes (not shown) or other means may be attached to the
inner wall of pipe 34 or to the end of the nozzle 226, for directing the flow of gypsum slurry
around the outlet port 186 so as to avoid fluid pressure of the moving gypsum slurry stream
being directed onto the nozzle, which because of its shape and size may be then better able to
withstand that pressure.
It is advantageous and preferable that the additive be applied within the dense gypsum
slurry so as to avoid further dispersion thereof, for example, if the additive were simply
sprayed over the surface. In such an example, the water film provided over the surface of the
gypsum board at the point in the gypsum board formation process, known in the gypsum
board industry, may further disperse the additive if applied on the surface only. At this point,
there is a measure of control that can be provided over the board manufacturing process by
introducing formulation additives to increase or decrease the speed of recrystallization of the
gypsum form solution or slurry form.
Ideally, either the polymer additive or the wax emulsion in the gypsum slurry solution
may be used to enhance the bonding strength also between the core slurry 44 and the outer
surface dense slurries 38, 138 and between the dense slurry that extends across and through the
mats of the glass fiber facing sheets 14 and 114'. The polymer may be generating a polymer
matrix that extends from the junction of the lower density core slurry and into the dense slurry
layers 38,138, which have penetrated through the sheets 14,114, and to extend to the gypsum
board surface. The polymer matrix is effectively embedded within the gypsum base and
provides a coalescing surface upon which further finishing can be based, e.g., painting or a
water impervious acrylic cover, that may be added at this stage of the finishing process, for
example, by spray coating.
The surface texture of the front face of the completed gypsum board may additionally
include these additives, which as a part of the underlying matrix, help present a smooth dense
layer of gypsum to which other polymeric, e.g., acrylic, compounds can adhere. As the dense
slurry layer cures, for example, in the drying process, it hardens to provide a stiff surface
capable of retaining a load and repelling water. The surface having the polymer additive,
improves water resistance and the other additives may provide specific sites for chemical
adhesion by other polymers. The composition of a water resistant or impervious coating can

additionally comprise one or a combination of the following polymeric compounds:
polyacrylamide, polymethylacrylamide, polyvinyidene chloride (PVDC), polyamide, poly
(hexamethylene adipamide), polyvinylchloride (PVC), polyethylene, cellulose acetate,
polyisobutylene, polycarbonate, polypropylene, polystyrene, styrene, butadiene, styrene
butadiene copolymer, polychloroprene, styrene, butadiene (Neoprene®), natural rubber, poly
(2,6 dimethyl pentene oxide), poly (4-methyl-1-pentene) (Teflon®), natural rubber, poly (2,6
dimethyl pentene oxide), poly 4, methyl pentene-1 and polydimethyl siloxane, and may be
used in either or both of the dense slurry layers, and in different concentrations even in the
core gypsum layer.
Testing of the gypsum board products comparing those with the wax emulsion
additive and those without, revealed a significant increase in water resistance, especially
when utilized with other water resistant additives in the core and modified dense gypsum
slurry layers. The testing results of samples indicate an average increase in water resistance
of at least 300%, and certainly, meeting and exceeding the minimum requirements and
standards promulgated by the Canadian Construction Materials Center. The data appears to
provide support to the theory of better dispersion across the complete surface of the board,
thereby enhancing performance of the surface of the dense slurry layer. Additional benefits
may be obtained by varying the wax emulsion or other compounds used, or a combination of
compositions, or varying other parameters such as the solution strength, the application rate
and the time and condones of curing, so as to increase the final gypsum board product's water
resistance and other desirable characteristics.
This invention has been described with reference to the above-disclosed
embodiments. Modifications and alterations of the disclosed embodiments are within the
ability of persons having ordinary skill in the gypsum board art, and this invention is not
intended to be limited to the description of the disclosed embodiments, the invention being
limited only by the following claims and equivalents thereof.

WE CLAIM:
1. A method of manufacture of gypsum board having fiber face sheets,
comprising the steps of:
providing a first gypsum slurry (38) having a first consistency continuously
passing through a first gypsum slurry transport receptacle (34);
depositing a predetermined amount of said first gypsum slurry (38) onto at least
a first continuous fiber face sheet (14);
transporting said first continuous fiber sheet through a gypsum application
station;
providing a second gypsum slurry (44) having a second consistency and
depositing said second gypsum slurry onto said first fiber sheet (14) and causing said
second gypsum slurry to be essentially evenly distributed over an upwardly facing top
surface of said first fiber sheet;
wherein the step of depositing the second gypsum slurry (44) is preceded by a
step of homogeneously mixing an additive into the first gypsum slurry (38) via a fluid
feed in fluid communication with said first gypsum slurry transport receptacle (34).
2. The method of manufacture of gypsum board as claimed in claim 1, wherein
said step of mixing an additive into one of said first gypsum slurry involves mixing a
wax emulsion into said first gypsum slurry.
3. The method of manufacture of gypsum board as claimed in claim 1, wherein
mixing of the additive into gypsum layer comprises utilizing a turbulator device (220)
to inject the additive into the slurry stream being transported through the first gypsum
slurry transport receptacle.
4. The method of manufacture of gypsum board as claimed in claim 1, wherein
said first continuous fiber sheet comprises randomly aligned, inorganic glass fibers
having random interstices between said fibers, so that depositing said predetermined
amount of said first gypsum slurry onto the first continuous inorganic fiber face sheet

causes the first gypsum slurry having a first consistency to penetrate through said
random interstices between the inorganic fibers and to thereby coat both top and
bottom surfaces of said first inorganic fiber sheet with said gypsum slurry having a
first consistency and said entrained additive.
5. The method of manufacture of gypsum board as claimed in claim 2, wherein
said wax emulsion is added to the continuous stream of gypsum slurry by injecting it
thereinto through a turbulator device (220) disposed in-line with the fluid feed at its
connection with first gypsum slurry transport receptacle.
6. The method of manufacture of gypsum board as claimed in claim 1, wherein
said additive is transported through the fluid feed by impelling it to move through the
fluid feed by a positive displacement pump (198).
7. The method of manufacture of gypsum board as claimed in claim 1, which
involves a step of providing a third gypsum slurry (138) having a third consistency
and depositing it onto a second continuous fiber sheet (114) having top and bottom
surfaces, whereby said top surface of said second fiber sheet is coated with said third
gypsum slurry.
8. The method of manufacture of gypsum board as claimed in claim 7 involving a
step of applying said second fiber sheet (114) onto the second gypsum slurry thereby
sheathing said second gypsum slurry within said first and second fiber sheets to form a
wet gypsum board product.
9. A gypsum board forming device comprising means for supplying continuous
sheet of material, a gypsum slurry mixer (30), and:
a gypsum delivery mechanism having a first gypsum slurry transport receptacle
(34), disposed at least at one gypsum delivery station for delivering a first gypsum
slurry (38) onto said continuous sheet (14),

at least one additive assembly (200) connected to an additive fluid feed (188)
for adding a homogenous stream of an additive to the first gypsum slurry (38) in a first
gypsum slurry transport receptacle (34),
a gypsum core delivery mechanism having a second gypsum slurry transport
receptacle (48),
a sheet joining station (80) for joining a further continuous sheet (114) to said
core gypsum (44), and
a gypsum conveyor line, having a belt with a surface for conveying formed
gypsum board from the sheet joining station, the at least one additive assembly
comprising:
an additive delivery port (186) in fluid communication with the additive fluid
feed; a turbulator (220) disposed in-line with the additive fluid feed, the turbulator
comprising a constrictor valve (224) having an outlet, the constrictor valve outlet
being disposed adjacent the gypsum slurry stream being transported through the first
gypsum slurry transport receptacle.
10. A gypsum board forming device as claimed in claim 9, wherein said constrictor
valve outlet disposed adjacent the gypsum slurry stream being transported through the
first gypsum slurry transport receptacle is in fluid communication with the additive
reservoir (192) by means of an in-line positive displacement pump (198).
11. A gypsum board forming device as claimed in claim 9 or 10, wherein said
additive comprises a wax emulsion.
12. A gypsum board forming device as claimed in claim 9 or 10, wherein said
additive comprises microfibers.


ABSTRACT

METHOD OF MANUFACTURE OF GYPSUM BOARD AND DEVICE
THEREFOR
The present invention discloses a method of manufacture of gypsum board having
fiber face sheets, comprising the steps of providing a first gypsum slurry (38) having a
first consistency continuously passing through a first gypsum slurry transport
receptacle (34), depositing a predetermined amount of said first gypsum slurry (38)
onto at least a first continuous fiber face sheet (14), transporting said first continuous
fiber sheet through a gypsum application station, providing a second gypsum slurry
(44) having a second consistency and depositing said second gypsum slurry onto said
first fiber sheet (14) and causing said second gypsum slurry to be essentially evenly
distributed over an upwardly facing top surface of said first fiber sheet, wherein the
step of depositing the second gypsum slurry (44) is preceded by a step of
homogeneously mixing an additive into the first gypsum slurry (38) via a fluid feed in
fluid communication with said first gypsum slurry transport receptacle (34). A
gypsum board forming device for carrying out the method is also disclosed.

Documents:

01580-kolnp-2007-abstract.pdf

01580-kolnp-2007-claims.pdf

01580-kolnp-2007-correspondence others 1.1.pdf

01580-kolnp-2007-correspondence others.pdf

01580-kolnp-2007-description complete.pdf

01580-kolnp-2007-drawings.pdf

01580-kolnp-2007-form 1.pdf

01580-kolnp-2007-form 3.pdf

01580-kolnp-2007-form 5.pdf

01580-kolnp-2007-gpa.pdf

01580-kolnp-2007-international publication.pdf

01580-kolnp-2007-international search report.pdf

01580-kolnp-2007-pct request.pdf

01580-kolnp-2007-priority document.pdf

1580-KOLNP-2007-(13-01-2012)-ABSTRACT.pdf

1580-KOLNP-2007-(13-01-2012)-AMANDED CLAIMS.pdf

1580-KOLNP-2007-(13-01-2012)-AMANDED PAGES OF SPECIFICATION.pdf

1580-KOLNP-2007-(13-01-2012)-DESCRIPTION (COMPLETE).pdf

1580-KOLNP-2007-(13-01-2012)-DRAWINGS.pdf

1580-KOLNP-2007-(13-01-2012)-EXAMINATION REPORT REPLY RECIEVED.PDF

1580-KOLNP-2007-(13-01-2012)-FORM 1.pdf

1580-KOLNP-2007-(13-01-2012)-FORM 2.pdf

1580-KOLNP-2007-(13-01-2012)-OTHERS-1.pdf

1580-KOLNP-2007-(13-01-2012)-OTHERS.pdf

1580-KOLNP-2007-(13-01-2012)-PETITION UNDER RULE 137-1.1.pdf

1580-KOLNP-2007-(13-01-2012)-PETITION UNDER RULE 137.pdf

1580-KOLNP-2007-(13-02-2012)-CORRESPONDENCE.pdf

1580-KOLNP-2007-ASSIGNMENT 1.2.pdf

1580-KOLNP-2007-ASSIGNMENT-1.1.pdf

1580-KOLNP-2007-ASSIGNMENT.pdf

1580-KOLNP-2007-CORRESPONDENCE 1.2.pdf

1580-KOLNP-2007-CORRESPONDENCE 1.4.pdf

1580-KOLNP-2007-CORRESPONDENCE-1.3.pdf

1580-KOLNP-2007-EXAMINATION REPORT.pdf

1580-KOLNP-2007-FORM 1-1.1.pdf

1580-KOLNP-2007-FORM 1-1.2.pdf

1580-KOLNP-2007-FORM 1.pdf

1580-KOLNP-2007-FORM 13-1.1.pdf

1580-KOLNP-2007-FORM 13-1.2.pdf

1580-KOLNP-2007-FORM 13.pdf

1580-KOLNP-2007-FORM 18.pdf

1580-KOLNP-2007-FORM 3-1.1.pdf

1580-KOLNP-2007-FORM 3-1.2.pdf

1580-KOLNP-2007-FORM 3-1.3.pdf

1580-KOLNP-2007-FORM 3.pdf

1580-KOLNP-2007-FORM 5-1.1.pdf

1580-KOLNP-2007-FORM 5-1.2.pdf

1580-KOLNP-2007-FORM-13 1.3.pdf

1580-KOLNP-2007-GPA.pdf

1580-KOLNP-2007-GRANTED-ABSTRACT.pdf

1580-KOLNP-2007-GRANTED-CLAIMS.pdf

1580-KOLNP-2007-GRANTED-DESCRIPTION (COMPLETE).pdf

1580-KOLNP-2007-GRANTED-DRAWINGS.pdf

1580-KOLNP-2007-GRANTED-FORM 1.pdf

1580-KOLNP-2007-GRANTED-FORM 2.pdf

1580-KOLNP-2007-GRANTED-SPECIFICATION.pdf

1580-KOLNP-2007-NOTARIAL CERTIFICATE.pdf

1580-KOLNP-2007-OTHERS 1.3.pdf

1580-KOLNP-2007-OTHERS-1.1.pdf

1580-KOLNP-2007-OTHERS-1.2.pdf

1580-KOLNP-2007-PA.pdf

1580-KOLNP-2007-REPLY TO EXAMINATION REPORT-1.1.pdf

1580-KOLNP-2007-REPLY TO EXAMINATION REPORT.pdf

abstract-01580-kolnp-2007.jpg


Patent Number 253074
Indian Patent Application Number 1580/KOLNP/2007
PG Journal Number 26/2012
Publication Date 29-Jun-2012
Grant Date 25-Jun-2012
Date of Filing 03-May-2007
Name of Patentee BPB LIMITED
Applicant Address ALDWYCH HOUSE, 81 ALDWYCH, LONDON WC2B 4HQ
Inventors:
# Inventor's Name Inventor's Address
1 HENNIS, MARK, E. 1795 WOODRIDGE DRIVE CLEARWATER FL 33765
2 FAHEY, MICHAEL, P. 9232 TREASURE LANE NE ST. PETERSBURG FL 33702
3 CHOWNING, MATTHEW, J. 2120 GENTLE STREET CODY WY 82414
4 BOYDSTON, GERALD, D. 124 SIDDLE DRIVE CODY WYOMING 82414
5 STUART, TROY, R. 2320 STEADMAN ST CODY WY 82414
6 HAUBER, ROBERT, J. 88 COUNTY ROAD CODY WYOMING 82414-7716
PCT International Classification Number B28B 19/00
PCT International Application Number PCT/IB2005/004064
PCT International Filing date 2005-10-13
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10/968,680 2004-10-19 U.S.A.