Note: Descriptions are shown in the official language in which they were submitted.
1'~32739~
- 1 - LFM-7342
BUILDING TWIRLS COMPRISING NON-WOVEN WEBS --
it
The present invention relates to building
products and more particularly to apparatus and
processes for maying building products comprising -
non-woven webs or mats.
Background of the Invention
Techniques of forming non-woven webs from
substantially dry components have long been recognized
in the art; however, with the advent of high energy
costs, the desirability of using such techniques rather
than wet-forming processes has become even more evident. ---
nevertheless, substantial problems have been encountered
in preparing Reformed web materials having a rota-
lively uniform structure. This invention concerns --
certain special apparatus and processes which may be ---
utilized to prepare such uniform non-woven webs, as well -
20 as products comprising these webs. --
The Prior Art -:
- -
Several patents are of particular interest in
relation to the present invention. US. Patent -
3,356,780 disclosed apparatus for making fabric. A mix- Jo
25 lure of fibrous particles and binder was fed into a --
chamber where it was contacted with a rapidly rotating
cylinder and a pressurized air stream. The rapidly -
UP
, . , I, . , " . , " , , . - . - . .. -, . . . .. .. .... . . .. . . .. ..... .................................... ........... .... .......... ..
. .... ....
~232734
rotating cylinder and air hurled the fibers toward
slowly rotating pheromones cylinders which had an
interior vacuum. The fibers and binder were matted onto
the cylinders which rolled together to form a layered
fibrous maternal. US. Patents 4,097,209 and 4,146,564,
both of which issued to J. R. Gorky et at., concerned
apparatus and a process, respectively, for forming a
mineral wool fiberboard product. A mixture of mineral
wool fiber and binder was prepared and fed through a
venturi into a relatively high velocity air stream such
that the mixture of material was entrained and carried
to a mat-forming zone. In the mat-forming zone the
material was layered onto converging pheromones wires by
exhausting the air through the pheromones wires. The
wires were then converged to give a mineral wool
fiberboard product. Unfortunately, the processes and
apparatus of Gorky et at. possessed features which
essentially restricted them to the production of rota-
lively thick gauge materials which had highly variable
basis weights.
More recently, US. Patent 4,394,411 issued to
M. Creole et at. and described a new method of preparing
a gypsum board panel faced on both sides with a mineral
or fiberglass fabric. The panel was prepared by
laminating two types of fabric together and then
interfacing the bonded fabric with the gypsum whereby
the larger diameter fibers were on the interior face
adjacent to the gypsum core, and the smaller-diameter
fibers were on the exterior face. An essential feature
of the invention was the inclusion of aluminum
hydroxide, iron hydroxide or silicon hydroxide as a
filler in the bonding agent which laminated the two
fabric types together. The invention did not concern an
integrated, one-pass process and was restricted to the
production of gypsum board.
Accordingly, one objective of the present
invention is to provide integrated processes which produce
non-woven webs and other
~23273~
-- 3
building materials having uniform basis weights.
Another objective of the present invention is to
provide composite sandwich-like building materials which
can be structurally varied as desired to provide good
acoustical properties or good strength characteristics.
Yet another objective of the present invention is to
provide processes which are more versatile than the
processes presently known in the art.
In accordance with the present teachings, a process
is provided for forming a groove molded building board
which comprises the steps of aerodynamically forming two
generally uniform non-woven webs consisting essentially
of organic binder and mineral wool; disposing a core mixture
comprising organic binder and filler between the webs;
consolidating the webs and the core mixture to provide a
composite structure; optionally, preheating the composite;
simultaneously compressing, grooving, curing, and optionally
embossing the structure, thereby providing a groove molded
board comprising at least one board segment; and separating
the board segments from the board scrap and from any adjacent
board segments, the grooving being sufficient to provide edge
detail to the board segment and to provide lines of demarcation
between the board or board segments and the scrap without
causing premature separation along the lines.
In accordance with a further aspect of the present teach-
ins, a composite suitable to provide a groove molded building
board is provided, the composite comprising a core material
comprising organic binder and filler, the core material being
covered by aerodynamically formed generally uniform webs con-
sitting essentially of organic binder and mineral wool, the
components of the webs and the core material being selected
such that, when the composite is subjected to conditions which
will induce simultaneous compression, grooving, curing and
optional embossing, the webs will stretch and move so as to
accommodate the contours which are impressed into their rest
pective surfaces, and the underlying core material will
similarly flow to adopt said contours.
- lZ32'734
- pa -
In accordance with yet another aspect, a groove molded
building board is provided comprising a composite of a core
material covered with aerodynamically formed generally uniform
non-woven webs, the board having dimensions, edged detail and
optionally embossed features obtained by the simultaneous come
press ion, grooving, curing and optional embossing of the uncured
composite, the core comprising organic binder and filler and the
web consisting essentially of organic binder and mineral wool.
These and other objectives of the present invention will
become apparent from the description of preferred embodiments
which follows.
B _ f Description of the Drawings
FIG. 1 illustrates apparatus for preparing a non-woven
web of the present invention, said apparatus comprising means
lo for preparing a mixture comprising binder and fibrous material,
a mat-forming zone and means for processing the mat which is
produced.
FUGUE illustrates an end view of a mat-forming zone of the
present invention taken along lines DUD of Foggily.
FUGUE illustrates a plan view of a preferred aperture through
which air enters a mat-forming zone.
FUGUE illustrates apparatus comprising two mat-forming zones
of the present invention.
FUGUE illustrates a cross-sectional view of an uncured
board blank in an open press assembly.
FUGUE illustrates a cross-sectional view of a grooved and
embossed board following the grooving, embossing and curing step.
FUGUE illustrates a board with a low-angle edge.
FUGUE illustrates a board with a high-angle edge.
FUGUE illustrates a plan view of an unsectioned groove-
molded board.
~232734
- 4 - LFM-7342
Summary of the Invention
A mixture of binder and fibrous material is
introduced into the upper regions of a mat-forming zone.
The mixture is intersected by a horizontally or upwardly --
directed air stream and entrained therein, then layered
onto at least one pheromones wire by exhausting the
entraining air through said pheromones wire or wires. -
By reducing turbulence and by controlling the manner in -
which the particulate matter is deposited upon the
10 pheromones wires, uniform non-woven webs can be obtained -
which may be used in a variety of ways to form versatile --
building products. -
Detailed Description of Preferred Embodiment --
In one embodiment the present invention comprises a
15 process for forming a non-woven web, said process --
comprising the steps of preparing a mixture comprising a I-
binder and principally inorganic fibrous material; -
introducing said mixture into the upper regions of a if-
mat-forming zone comprising a first movable pheromones I-
20 wire disposed in the lower region thereof and,
optionally, a second movable pheromones wire disposed --
so as to converge with said first pheromones wire at a t
nip opening disposed there between, said mixture being
introduced through a first aperture such that it falls I:-
25 into and is entrained in a horizontally or upwardly r".
directed air stream which is introduced through a second -
aperture into said mat-forming zone, said second
aperture having means associated therewith for --
controlling the direction of the air which passes
30 there through; adjustable exhausting the entraining air -
through said wire or wires to selectively deposit said t
mixture thereupon, said second aperture and said
optional second pheromones wire being disposed relative I:
to said first pheromones wire such that the mixture I--
35 which is deposited on said wire or wires is deposited --
essentially uniformly; consolidating said deposited
mixture to yield a non-woven web of material; and I--
compressing and curing said material. k:'.. ''
- '-
123~73~
- 5 - LFM-7342
In a second embodiment the present invention
comprises a process for forming a building board
comprising a core material and non-woven outer surfaces,
said process comprising the steps of preparing a first .
5 mixture and a second mixture comprising a binder and --
principally inorganic fibrous material; introducing said :
first mixture into the upper regions of an upper
mat-forming zone and said second mixture into the upper -
regions of a lower mat-forming zone, each said .
mat-forming zone comprising a first movable pheromones
wire disposed in the lower region thereof and,
optionally, a second movable pheromones wire disposed I-
so as to converge with said first pheromones wire at a
nip opening disposed there between, each said mixture -
15 being introduced through a first aperture such that it -:
falls into and is entrained in a horizontally or -
upwardly directed air stream which is introduced through .
a second aperture into each said mat-forming zone, said
second apertures having means associated therewith for
controlling the direction of the air which passes
there through; adjustable exhausting the entraining air -
through said first pheromones wires and said optional
second pheromones wires to selectively deposit said
mixtures thereupon, said second apertures and said ..
25 optional second wires being disposed relative to said --
first pheromones wires such that the mixtures which are
deposited on said wires are deposited essentially .-.
uniformly; consolidating the deposited mixtures to ....
provide upper and lower webs of material; depositing a -.
core mixture comprising a filler and a binder on said
lower web of material; consolidating the resulting
layered material with said upper web to provide a -
composite structure; and compressing and curing said
composite structure. .
In a third embodiment the present invention -.-
comprises apparatus for forming a non-woven web, said .-
apparatus comprising (A) preparation means for preparing -.`
a mixture comprising a binder and principally inorganic -
, ... . .................. .......... ..... . ... ... . .. . .. ..... ..... .. .. . . .. . .. . .. .. ........... ..................
I,,,,.,.. ,, ,,, ,, ., " ,,,,,,,,,, ,,,,,,,, ,,, ,,,,..... ,...... .. . . ,,. ,.. -
. . . . : : : : . .. ., .. . . . , .. . .. . . . -
lZ32734
- 6 - LFM-7342
fibrous material; (B) a mat-forming zone feedibly
associated with said preparation means so as to receive
said mixture, said mat-forming zone comprising I a
first aperture in the upper regions thereof, said .. -
aperture comprising means for introducing said mixture
there through, I a second aperture disposed therein .--
such that air introduced through said second aperture is .-
horizontally or upwardly directed so as to intersect and .
entrain therein said mixture, said second aperture ..
having means associated therewith for controlling the
direction of the air which passes there through, (3) a ..
first movable pheromones wire disposed in the lower -.
region of said mat-forming zone, said wire exiting said .
mat-forming zone through a nip opening, and, optionally, ..
15 a second movable pheromones wire disposed so as to ...
converge with said first pheromones wire at said nip
opening, said optional second pheromones wire and said :-
second aperture being disposed relative to said first -.-
pheromones wire such that said mixture is deposited
20 essentially uniformly on said wires, (4) means for ..
adjustable exhausting the entraining air through said -
pheromones wires to selectively deposit said mixture I-
thereupon, and (5) means for moving said first
pheromones wire and said optional second pheromones wire
25 to said nip opening to form a non-woven web of material; .-
and (C) means for consolidating said web and setting --
said binder. ..
In a fourth embodiment, the present invention
comprises apparatus for forming a building material -
30 comprising a binder and principally inorganic fibrous ...
material, said apparatus comprising (A) preparation .-
means for preparing at least one mixture comprising a ..
binder and principally inorganic fibrous material; (B) a ..
first and a second mat-forming zone, each said zone
35 being feedibly associated with a preparation means so as ....
to receive a mixture therefrom and comprising (1) a :
first aperture in the upper region thereof, said
aperture comprising means for introducing said mixture .-
....
. . .
.. -. ................... ....... ... ... . .... ... ......... ..... ............. ..... . .. .. .. .... .
~Z3~7134
- 7 - LFM-7342
there through, (2) a second aperture disposed therein
such that air introduced through said second aperture is
horizontally or upwardly directed so as to intersect and
entrain therein said mixture, said second aperture
5 having means associated therewith for controlling the --:
direction of the air which passes there through, (3) a
first movable pheromones wire disposed in the lower -
region of said mat-forming zone, said wire exiting said ....
mat-forming zone through a nip opening, and, optionally, .. -.
10 a second movable pheromones wire disposed so as to :
converge with said first pheromones wire at said nip -
opening, said optional second pheromones wire and said .
second aperture being disposed relative to said first .. ::
pheromones wire such that said mixture is deposited ..
15 essentially uniformly on said wires, (4) means for --.
adjustable exhausting the entraining air through said -.
pheromones wires to selectively deposit said mixture --.
thereupon, (5) means for moving said first pheromones .-:
wire and said optional second pheromones wire to said .
nip opening, and (6) means for consolidating the
deposited material to provide a non-woven web of material, -
(C) means for converging the non-woven webs formed by
said first and second mat-forming zones; and ED) means
for consolidating said webs and setting said binders. or'
In a fifth embodiment, the present invention ..
comprises a building board comprising a composite of a .
core material covered with non-woven webs, said board
being obtained by forming two non-woven webs comprising -I.
generally uniform mixtures of binder and principally ..
30 inorganic fibrous material; disposing a core mixture -
comprising a binder and a filler between said webs; ...
consolidating said webs and said core mixture to provide
a composite structure; and compressing and curing said -
structure. .
In a sixth embodiment, the present invention
comprises a groove-molded building board comprising a .....
composite of a core material 'covered with non-woven or'',','
webs, said board having dimensions, edge detail and ..
. . .
1232734
- 8 - LFM-7342
optionally embossed features obtained by the
simultaneous compression, grooving, curing and optional
embossing of the uncured composite, said core comprising
a binder and a filler and said webs comprising generally -
uniform mixtures of binder and principally inorganic
fibrous material. -
In a seventh embodiment, the present invention
comprises a process for forming a groove-molded building
board, said process comprising the steps of forming two -
non-woven webs comprising generally uniform mixtures of
binder and principally inorganic fibrous material;
disposing a core mixture comprising a binder and a
filler between said webs; consolidating said webs and -
said core mixture to provide a composite structure;
optionally, preheating said composite; simultaneously
compressing, grooving, curing and optionally embossing ::
said structure, thereby providing a groove-molded board -
comprising at least one board segment; and separating
said board segment from the board scrap and from any
adjacent board segments, said grooving being sufficient
to provide edge detail to said board segment and to ---
provide lines of demarcation between said board or board I-
segments and said scrap without causing premature
separation along said lines.
In an eighth embodiment, the present invention
comprises a composite suitable to provide a groove
molded building board, said composite comprising a core ---
material comprising a binder and a filler, said core
material being covered by webs comprising generally
30 uniform mixtures of binder and principally inorganic :
fibrous material, the components of said webs and said
core material being selected such that, when said
composite is subjected to conditions which will induce -
simultaneous compression, grooving, curing and optional
embossing, said webs will stretch and move so as to
accommodate the contours which are impressed into their
respective surfaces, and said underlying core material --
will similarly flow to adopt said contours. ---
.....
. .
.. ......... ...... ............ .. . .. ...... ... . . .. .
- . . .. - ... -..... - -.,.. : : .: .- -: :. -:
1~327'34
- 9 - LFM-7342
I
The apparatus disclosed in US. Patent No.
4,09-1,209 has proved useful to produce mineral wool
products having a thickness of about one inch or more.
;. .
Although particle clumping and the presence of wave 1--
5 patterns have caused some difficulties, these L:::
difficulties have not been particularly significant
because the resulting product was intended to be of
thick gauge. However, where thinner gauge products were
desired, problems associated with the presence of clumps -
10 and waves proved to be virtually insurmountable.
Applicants herein have discovered that the
primary cause of these problems is the sequential
process of entraining the particulate matter in the air
stream and then subsequently introducing the entrained
it mixture into the mat-forming zone. A rapid air flow is
required in order to maintain entrainment. The feed --
mechanism which separates the bulk solids into
individual particles and introduces them into the air
stream tends to develop a static charge on the --
20 particles. The rapid air flow in combination with the
static charge results in turbulence and particulate :
clumping. Small clumps of material initially form on
the walls of the venturi, as well as in the forming
chamber. As the clumps collect more material, two .
25 effects are obtained. First, the clumps periodically
break loose and are deposited on the pheromones wires. -
Secondly, the clumps tend to chinless the passing air, g
thus causing non-uniform entry of the particulate matter g
into the mat-forming zone. This latter effect, in ' -
30 combination with the rapid entry of the entrained -
material into the mat-forming zone and across the 1:
surfaces of the pheromones wires, tends to cause uneven
deposition and wave patterns in material which is
deposited on the wires. Thus, the entrainment process -
35 is virtually precluded where uniform basis weights are -
desired.
Surprisingly, applicants have discovered that
remarkable improvements in basis weight uniformity can
. . . - .
. . . -
.....
.. . .
,. .... ..........................
11 Z32734
- 10 - LFM-7342
be achieved by separately introducing the particulate
matter and the air stream into the mat-forming zone, and
by making other significant changes in the prior art
process. By variably directing the air stream
horizontally or preferably upwardly into the particulate
matter which is introduced through an aperture located -
in the upper regions of the mat-forming zone such that
the particulate matter intersects and is entrained in - -
the air stream, and by locating the pheromones wires and
apertures in relation to one another such that the
entrained particles tend not to pass with high velocity
in a parallel fashion across the surfaces of the forum- -
noun wires prior to deposition, non-uniform deposition -
problems are dramatically reduced. As a result, uniform -
webs having uniform basis weights and thicknesses on the
order of 40 miss can be routinely produced.
Apparatus which is preferred to practice the ---
present invention is illustrated in FIG. 1. Several ---
features thereof were disclosed in US. Patent No.
20 4,097,209, especially the means for preparing the ---
particulate mixture and the curing and finishing means. ;~-
Mineral wool is typically received in bales 10 which
must be fragmented for use. FIG. 1 illustrates bales 10
residing on conveyor 11. The bales are partially
25 fragmented at 12, transferred to inclined conveyor 13 --
and then passed under flail 14 which causes initial
separation of bales 10 into fibers 15. From conveyor
13, fibers 15 fall onto conveyor 16 and are then fed
onto inclined pinned feeder conveyor 17. At the top of --
30 conveyor 17 the fibers are combed by rotary comb 18, --
thereby leveling the feed. The feed is doffed by roll --
19 into a gravimetric feeding device 20 comprising chute
21, compression rolls 22 and 23, and flow rate scale 24. ---
Device 20 then passes fibers 15 through feed rolls 25 --
and 26 onto fluffing roll 27. Fluffing roll 27 drops
fibers 15 onto conveyor 30 which conducts them beneath a -
binder adding station 31. sunder adding station 31 also
comprises a gravimetric feeding device (not illustrated) --
~232~34
LFM-7342
and it deposits a desired amount of binder 32 onto
fibers 15 carried onto conveyor 30. The layered fibers
15 and binder 32 are mixed with fluffing roll 33 and
then passed into fiberizing device 34 of first aperture
35 of mat-forming zone 36. Fiberizing device 34 -comprises feed rolls 40 and 41, licker in roll 42 and --
doffing brush 43.
Mat-forming zone 36, excluding wires 45 and -
46, is constructed where possible of material which is
10 substantially electrically non-conductive, such as ---
plexiglass. Although certain metal pieces are needed
for structural or other purposes, electrically conductive
surfaces tend to cause a plating out of static-charged ---
particles on those surfaces. Thus, they are to be avoided
whenever possible Pheromones wires commonly are
constructed of a conductive material and the use of such --
material for lower wire 45 is preferred. However, more --
latitude is permitted with upper wire 46 and it may be
constructed of a non-conductive material, such as plastic.
Air enters mat-forming zone 36 through second aperture
44 and entrains the mixture of mineral wool and binder. -
The entrained mixture is then felled onto first -
pheromones wire 45 and second pheromones wire 46 as
hereinafter described. Wires 45 and 46 are brought ---
together at nip opening 47, at which point the felled
mixture is consolidated in consolidation zone 48. Prior
to exiting from consolidation zone 48 at opening nip 49, ---
an upper tamping device 50 and a lower antistatic device -
51 assist in the separation of the consolidated material -
prom the pheromones wires. The consolidated material
passes across transfer rolls 52 and into oven 53, where I---
it may then be dried, cured and the like.
Although mat-forming zone 36, as illustrated, `
comprises first pheromones wire 45 and second pheromones -I
35 wire 46, which are preferred, it must also be noted --
that, in certain instances, it may be possible to --
dispense with second pheromones wire 46. Thus, wire 46
-
.... I.. , .,,.. ,,, . .... ,,,,.,,.. ,,,,,,, .,,,.,.,,,.. ,,,,,,,, ,,,, ,,,,, ,.,.,.,,.. ,.. ".",
lZ32~34
- 12 LFM-7342
could be replaced, for example, by a panel of non-conduc-
live material or a non-foraminous wire. Non-woven webs
produced using apparatus comprising only one pheromones --
wire might, in some cases, have relatively more random --
5 particle size distributions than webs produced using -I
apparatus comprising two such wires. Nevertheless, in
many instances, and particularly when producing cored
building boards, the random distribution of particles --
makes little difference in the resulting product.
When such modifications are employed, other
changes to the apparatus will also be required. For
example, if second wire 46 is replaced by a panel,
consolidation of the felled web could most conveniently
be accomplished at nip opening 47 using a seal roll.
Further, the absence of an upper wire in consolidation
zone 48 would, in most instances, obviate the need for
tamping device 50, whose primary function is to assist
in separating the web from said upper wire.
With the preferred arrangement illustrated in -
20 the figures, wire 45 passes in direction A through the -
lower region of mat-forming zone 36, whereas wire 46 -
enters mat-forming zone 36 by passing around wire roll r-'
58, moves in direction B toward nip opening 47 and !-
leaves mat-forming zone 36 by passing around wire roll
25 59. Pheromones wires 45 and 46 comprise means 60 to 63 --
to exhaust air through said wires. Mat forming zone 36
also comprises ceiling sections 64 and 65, shroud 66
which houses fiberizing device 34, back panel 67, and
side panels 68 and 69 (FIG. 2). --
Second aperture 44 is disposed in back panel ---
67 and is directed upwardly such that air introduced I-
into mat-forming zone 36 through said aperture generally --`
passes in direction C. It is also possible to have air --
entering through aperture 44 in a horizontal manner; --
however, less satisfactory felting is achieved with a
horizontal configuration. Further, as a note of
caution, downwardly directing the air through aperture -
44 should be avoided because extremely poor results are
often obtained. --
. .
I''
123Z734
- 13 - LFM-7342
Although the preferred arrangement illustrated
in the figures shows apertures 3 5 and 44 as individual
openings, the present invention also contemplates those
devices which, because of size or other considerations,
comprise multiple apertures which introduce particulate --
matter or air into the mat-forming zone. Accordingly,
the use of singular terminology herein will be deemed to --
include a plurality of the indicated device. --
Preferably, second aperture 44 will also
comprise means to variably control the direction of the
.. .
incoming air as it enters mat-forming zone 36.
Oscillating vanes have proved to be especially suitable :
and are illustrated in FIGS. 2 and 3, FIG. 2 being taken -
along lines D-D of FIG. l, and FIG 3 being a plan view L
of second aperture 44.
Second aperture 44 is comprised of side panels
73 and 74, top panel 75, and bottom panel 76, the two
ends of said aperture being open. Disposed within said --
aperture is a series of vanes 77. Vanes 77 are mounted
on pins 78 which are rotatively contacted with top panel -
75 and bottom panel 76 such that vanes 77 pivot about -
the axes of pins 78. The ends of vanes 77 lying
furthest from mat-forming zone 36 are connected to a
vane oscillating shaft 79 by oscillator shaft connectors to-
2 5 80. Although the illustrated vane arrangement has r
proved to be particularly suitable to control the .!''''
direction of air flow, other flow control means disposed
in or behind second aperture 44 or in mat-forming zone --
36 may also be used to advantage. Thus, all such flow ':
control means are contemplated by the present invention. ,-
In operation, first pheromones wire 45 and ,--
second pheromones wire 46 are moved in directions A and -I
B (FIG. l), respectively, so that they converge at nip i-
opening 47. Exhaust means 60, 61 and 62 draw air from
mat-forming zone 36 through said first pheromones wire, -
and exhaust means 63 draws air through said second
pheromones wire. The exhausted air is replaced by air r
entering the mat-forming zone through second aperture
.
t-'
to-
.. ........... ........ . . ... . . . . .
~Z3Z734
- 14 - LFM-7342
44. Thus, a negative pressure is always maintained in
mat-forming zone 36.
Mineral wool is the preferred inorganic
fibrous material which will be used to practice the -
5 present invention and it typically consists of pieces I-
which vary substantially in diameter and length; --
however, because mineral wool tends to be brittle, the --
processing steps from fragmenting device 12 through
fiberizing device 34 usually produce fibers that do not
exceed about 12mm in length. Other fibers may also be
included. Examples of such materials are inorganic
fibers such as glass, ceramic and wollastonite; natural I--
fibers such as cotton, wood fibers, or other cellulosic ---
materials; and organic fibers such as polyester or
15 polyolefins. In addition, other materials such as I--
puerility and various clays may also be included.
The binders which may be employed in forming
the webs will typically be of the type described in US.
Patent 4,097,209 and 4,146,564 in that they should be --
susceptible to entrainment such that a substantially
proportional mixture of binder and fiber is deposited on
wires 45 and 46. Examples of such binders are novalac -
phenol formaldehyde resins, starch, melamine-formalde-
Hyde resins, urea-formaldehyde resins, epoxy resins, and
25 the like. !:
When a mixture of binder and principally
inorganic fibrous material is introduced through first
aperture 35, it is intersected by the upwardly directed
air entering through second aperture 44. The vane ---
arrangement of second aperture 44 variably channelizes
the air, and aperture 44 preferably is directed so that I-
the air intersects the mixture of material immediately t
below first aperture 35. The resulting entrained mix-
lure of material is deposited on first and second lore- --
35 minus wires 45 and 46 as the entraining air is -
exhausted through said wires. The manner in which air -
is exhausted through said wires may be varied as desired
by the artisan to obtain products having various
:....
, . .
: . ,,,.. ,,, .,.. ,., .. ,.,.. ,, .,,.,.,. .. , ., .. , . ., .. ,, . ,.. ,,.. ", .. ,.. , .. , ,., .,,, .,.,, ,,. ", ,",.. ..
- ,.............. . ....... ..
~23Z713~
- 15 - LFM-7342
characteristics. Although a single exhaust means may be
utilized behind each wire, the figures illustrate
multiple exhaust means 60, 61 and 62 disposed below
first pheromones wire 45~ Thus, air exhaustion may be ---
varied in two ways; namely, by varying the amount
exhausted through different areas of a single wire,
e.g., via means 60, 61 and 62, and by varying the
relative amounts which are exhausted through the upper ---
and lower wires 46 and 45. ---
When multiple exhaust means are used, the
shorter particles tend to follow the air stream such :
that they are deposited on those portions of the wires -
through which the majority of the air is exhausted.
Accordingly, if 90% of the air is being exhausted
through one wire, the majority of the shorter particles
. . .
will be deposited on that wire. As another con- :
side ration, stratification and basis weight control will
also be affected by variably exhausting the air through
different portions of a single wire. It should there --
fore be apparent that, where thin-gauge webs are
desired, variable exhaustion of the air via means 60, 61
and 62 is very advantageous. In such circumstances, the -
majority of the air is preferably exhausted through wire
45 toward the back of the mat-forming zone by use of
25 exhaust means 62, with lesser amounts being exhausted -
using exhaust means 60 and 61. ---
Although variable air exhaustion can lead to a
certain amount of particle classification, the skins -
which are produced are nevertheless generally uniform
throughout their thickness with respect to fiber
diameter distribution and fiber/binder composition.
Accordingly, the skins which are produced differ from
those described in U. S. Patent 4,394,411. That
reference discloses that two fabrics are formed such
that one fabric contains fibers which are substantially
thicker than the fibers of the other fabric. The two ---
fabrics are then bonded together with an adhesive layer -
which contains aluminum, iron or silicon hydroxide it
....
....
I. =,.,'''.,'',",,'',','.,' I.
1232~34
- 16 - LFM-7342
fillers. The bonded fabric has a decidedly luminary
construction because the bonding agent lies essentially
between the fabric layers. No hydroxide fillers are
necessary to practice the present invention and, because -
of the method of formation, the binder is distributed in
a generally uniform manner throughout the skin. -
Variable air exhaustion is another way of -
avoiding turbulent passage of the entrained material -
across the surface of wire 45 near nip opening 47, the -
10 implications of which are referred to below. Variable -
exhaustion also provides an alternative to the ---
replacement of second pheromones wire 46 by a panel or a
non-foraminous wire. Thus, by merely turning off the ::
exhaust means behind wire 46, essentially all of the air -
would be exhausted through first pheromones wire 45.
However, this alternative is not entirely satisfactory
because, even when all of the air passes through wire -
45, certain of the particulate matter tends to stick to
wire 46, leading to some gauge variation in the
20 resulting product. -
One significant drawback of the apparatus -
disclosed in US. Patent 4,097,2Q9 was the lack of ::
uniformity of the material obtained. A number of
factors which contributed to the non-uniformity have
25 been set forth above; however, another factor which has -
not been mentioned is the narrow Angie of incidence I--
between the converging pheromones wires. Because of -
this narrow angle, when the entrained material entered
the mat-forming zone, the particulate matter tended to
30 sweep with high velocity across the surfaces of the I--
pheromones wires. This turbulent passage was compounded ---
by the static charges present on the entrained material, -
resulting in wave patterns in the deposited material.
For these reasons, the angle between wires 45 ,
35 and 46 at nip opening 47 should be such that a turbulent l-:
passage of the entrained material across the surfaces of
said wires is avoided. The angle illustrated at the nip
opening of the apparatus described in US. Patent l-
I':'...'
1~3~'734
- 17 - LFM-7342
4,097,209 is about 12 degrees; however, it has been
found with the present invention that angles of not less
than about 20 degrees are preferred. Furthermore, the
angle should not be too great because any material
deposited on wire 46 will tend to crack or fall off the
wire as it passes around wire roll 59, especially if
thick mats are being produced. Accordingly, a maximum
angle of not more than about 55 degrees is preferred.
In addition to the horizontal or upward -
introduction of air through second aperture 44, which
was referred to earlier another factor which affects
the manner in which the particulate matter is deposited
upon said pheromones wires is the location at which -
second aperture 44 is disposed in back panel 67. If the
15 point of intersection of the incoming air and the 'I-
particulate matter is too far below aperture 35, -
suitable entrainment may not occur and the particulate
matter may tend to pass across first pheromones wire 45 -
at a relatively flat angle. Both effects tend to -
20 encourage wave patterns and non-uniformity. -
Accordingly, it is preferred that second aperture 44 be --
disposed in the upper portions of back panel 67.
Similar problems can also be encountered if second
aperture 44 is downwardly directed into the particulate En
25 material, or if it is too far away from first aperture -
35. For apparatus constructed as illustrated in the
figures and having approximate dimensions as hereinafter -
described, we have found that the best results are
obtained if the distance between first aperture 35 and --
30 first pheromones wire 45 is not less than 36 inches, and ---
if the distance between the inner end of second aperture
-
44 and the point where the upwardly directed air stream
intersects the mixture of material is approximately 24
inches.
Although these results may also be varied
somewhat by increasing the angle at nip opening 47, this -
angle and the disposition of second aperture 44 may both -
be varied to achieve the same result. Accordingly, it
.....
. . .
1~32734
- 18 - LFM-73~2
should be kept in mind that it is desired that the
particulate matter approach tune surfaces of said
pheromones wires 45 and 46 in a non-turbulent and
approximately non-parallel manner. -The vanes disposed in second aperture -
44 provide a particularly valuable contribution to the
present invention. The build-up of wave patterns with
time in the prior art apparatus was due in part to
channelization caused by the static-induced deposition :-
of the particulate materials in various parts of the
passage through which the entrained material passed, and
in part to the manner in which the entrained material
passed across the material which had previously been :-
felled on the pheromones wires. Vanes 77 tend Jo ---
eliminate this problem by oscillating back and forth.
As shaft 79 oscillates back and forth generally along :
path EN (FIG. 3), the vanes are aimed first toward one ---
side of mat-forming zone 36 and then to the other side --
of said zone. As a result, there is little opportunity
20 for channelization to occur and the particulate matter -
which is deposited on pheromones wires 45 and 46 is much -
more uniform. I
The superiority of the present invention can
clearly be seen from the nature of the material produced
25 by the present apparatus according to the present :-
process. As previously indicated, only relatively thick --
products could be obtained utilizing the prior art
devices. For example, when a mixture of binder and -
mineral wool fiber was entrained in an air stream and
30 conducted into the mat-forming zone described in US. -
Patent 4,097,209, materials approximately one inch or -
more thick and having many areas of non-uniformity were -
obtained. Thick products can also be produced according
to the present invention; however, they can be produced
35 at high line speed, and they have none of the clumps or ---
wave patterns inherent in the prior art products. ---
As another exemplify the superiority of the
present invention, attempts according to the prior art
... . ........ .............. ............... .. ..... . .. . . . . . .. ... ...... . . .............. ................ .............................. .........
.. .
.................................................................................................................................................
1232,~34
- 19 - LFM-7342
to obtain thinner materials were totally unsuccessful
because of the clumps which were found in the final
product. No such difficulties are encountered with the
present invention. Indeed, non-woven webs having :-
5 uniform basis weights and thin-gauge construction have -I
been obtained using the present apparatus and practicing
the present processes. The advantages of such thin
layers of material are remarkable. For example, by
utilizing two mat-forming zones as described herein, it --
10 is possible in an integrated, single-pass operation to -
form sandwich-like building products having thin outer
skins and a center core. An example of such apparatus -
is illustrated in FIG. 4, in which the means for
preparing the particulate mixture and the curing and --
finishing means are not shown.
Lower mat-forming zone 83 and upper
mat-forming Noah 84 are constructed as previously
described and, as with the individual mat-forming zones, -
they may optionally comprise one or two pheromones --
wires. Each zone is provided with mixtures of binder
and an appropriate fibrous material which are converted
into webs of material as previously described. The webs l:-
emerge from zones 83 and 84 at opening nips 85 and 86,
respectively. The lower web 87 is conveyed from
25 conveyor 88 across transfer rolls 89 and onto conveyor I
90. Core deposition station 91 then deposits core -
mixture 92 onto web 87, and screwed 93 levels the core ---
material. Station 91 comprises a gravimetric feeding
device (not shown), such as that which has previously
30 been described. :::
Meanwhile, upper web 94 emerges from opening -
nip 86, passes across transfer rolls 95 onto conveyor 96 -
and down slide tray 97 which deposits it on the top of -I
the leveled core mixture. The loose composite may be ---
35 compressed by recompression assembly 98, in which case --
it emerges from opening nip 99 as a structure which has l--
sufficient strength to permit it to be conveyed through
further processing and curing steps without sustaining
-
-
. . . . . .. . . . .. ...... .... ........ .. ..... ... .... .. ..... ... ....... ... . .. .. .. .. . . .. ...... ... .... ... ... ... . .. ... ...
.
1;232734
- 20 - LFM-7342
significant damage.
A wide diversity of products may be obtained _
through the use of this apparatus. For example, if a
mixture of expanded puerility and binder is used as the
core mixture, the products produced can be varied from
those having good acoustical properties to those having
high modulus of rupture values. Further, the board is
produced in a single pass operation which is unique.
The prior art teaches that certain sandwich-like
products may be produced by separately making the outer
skins and adhering them to a core material using a layer
of adhesive. The present invention is remarkably
superior, not only because of its simplicity in
avoidance of the adhesive layers, but also because, in -
15 one embodiment, the nature of the process permits a it,
differential densification of the product to occur -
without resorting to separate laminating and pressing
operations.
The aforementioned puerility cored product
provides a particularly good example of this phenomenon.
The outer layers of mineral wool and binder have a low
compressive strength whereas the expanded puerility core t.
has a relatively high compressive strength. When the
composite structure is compressed, the core acts as an -
25 anvil against which the outer layers are compressed. '--
This results in densification of the outer layers, but
essentially no densification of the core At the same
time the core tends to accommodate any irregularities in
the outer layers, thereby giving smooth outer surfaces -
30 with uniform density. ---
Another method of differentially densifying -
the composite structure involves the sequential curing -
of the core and the skins. For example, if a composite
structure is prepared comprising a core having a binder
that has a lower setting temperature than the binder for
the skins, and the composite is passed through a through --
convection oven which is adjusted to a temperature that I--
. ::
will cure the core binder but not the skin binder, a
.. . .
I,....... ,.,.. ,,.,.. , ". ,,.,,,,.. ,.,,." ,,,,",,,,, ,, , , . :,,,",.,,,.,,, ,,:.. ,
: I.......... .. ... ,.,.. , ,.. . .. ," .. ,.. ,.. ..... ,.. . ,. ,.. , .. ,. ,,. ,, "",.,,, "",, ", ,,.. ",
I- . : .. ,.. . :-: , ,,,,, "" ", ,, ,,""""",, ",, ,, ,,,,,,,",
AL ;~32~34
- 21 - LFM-7342
structure is produced having uncured skins. If these
skins are then compressed against the core and cured,
very dense skins can be produced. Similarly, the same
effect can be obtained by using binders with similar
5 setting characteristics, but excluding a necessary -
setting component from the skin binder. When the --
necessary component is subsequently added and the --
composite is compressed and cured, dense, hard skins are
again obtained An example of the latter alternative is -
the use of a binder such as a novalac phenol formalde-
Hyde resin from which the cross-linking agent, -:
hexamethylenetetramine, has been excluded.
As indicated, these processes are amenable to
the production of boards having good acoustical '-
15 properties with NRC values in excess of 50 without being I--
acoustically perforated. Surprisingly, the good --
acoustical properties can be retained even when the
boards are provided with a decorative finish, such as by
painting. Boards can be prepared as described above, -
20 provided with a paint coat, and punched in a manner well :~:
known in the art to give acoustical resonance cavities. ,--
As an alternative, however, acoustical board may be
obtained without punching. This can be achieved by
applying a paint coating directly to preferred types of I---
boards as hereinafter disclosed. When making acoustical
board, the core mixtures will preferably comprise
puerility having a particle size such that not more than ,--
about 15 percent of the puerility by weight is smaller -
than 50 mesh (US. Standard). Preferably, however, not -
more than about 5% of the puerility will have a mesh size
which is less than 50 mesh. r:::
The present invention also offers a remarkable !::
single-step means for preparing "equalized" building -
products that have been sized to specific dimensions.
In the conventional production of ceiling products, for
example, ceiling boards are formed by wet laying
processes. These products are not particularly amenable
to embossing procedures. If light embossing is used,
. . .
''''''''''-';
~1232734
- 22 - LFM-7342
poor clarity of design is obtained whereas, if heavier
embossing is used to improve the visual effect, cracks
form at shallow embossing depths, and board strength and
acoustical properties are lost.
Another deficiency in the production of
conventional, wet-laid ceiling board is the necessity of --
using elaborate procedures and expensive equipment to --
equalize the product and to produce facing designs. In --
the prior art, the wet formed blanket is usually cut
10 into blanks which have approximately square edges. -
These blanks are then equalized a second time so that,
when they emerge from the pressing and drying step, they
can be placed in register with the finishing saws; thus, -
at that point in the process, at least the leading edge
and one side should be in square relationship with one
another. The blank is then passed through a series of
saws which reduce it to its final size, produce --I
appropriate edge effects and if desired, provide a --
facial design; however, if proper registration is not -
maintained, thousands of feet of defective product can
be produced. In addition, because saws are used to ---
provide edge detail and facial designs, the patterns '-
which can be produced are quite limited. Therefore,
this multiple-step prior art process provides at least
25 four sources of error which can lead to the production -
of defective products: (1) lack of a square edge --
relationship such that registration cannot be -
maintained; (2) disorientation of the blank in pattern
application operations; (3) lack of registration of the --
3G saw blades or cutter blades to the pattern or the blank;
and (4) saw or cutter wear which, to be avoided,
requires constant maintenance. -
In contrast, the present invention offers a
single-step equalization process whereby a composite
structure of the present invention can be sized and
provided with edge detail. At the same time, at an
artisan's discretion, the upper board face can also be -
provided with an embossed pattern. Because this may be --
.....
Jo
1~2734
- 23 - LFM-7342
achieved without the use of saws, unique and complex
embossing designs and edge details, as well as odd-siæed
pieces, are producible according to this embodiment of
the invention. Examples of decorative edge detail which -I
can be provided in this manner are coved, chamfered,
beaded rabbited, Roman Ogled, rounded and Conga edges.
Further, no sawdust is created and the use of expensive
dust collecting equipment is obviated. It is noted,
however, that, at the artisan's discretion, the present
invention may be practiced in combination with prior art
equalization processes. ---
The ability to achieve these results appears --
to be attributable to the unique character of the
composite structure. In the uncured state, the upper
15 skin and the backing skin provide some strength and --
durability to the composite structure whereas the core
material is relatively pliable. Such structures can be
subjected to the embossing and groove-molding processes
described hereinbelow to yield products which, unlike -
20 similarly treated wet formed boards, are not cracked and --
torn, have good integrity, and demonstrate good --
acoustical performance. These results are apparently -
obtained because the upper facing skin can stretch in
response to the applied forces while the core material
flows and adopts the contour of the embossing/grooving
platen. The back skin, which usually is not embossed,
does not have to stretch and is merely consolidated.
A typical application of the embossing/grooving
process is illustrated as follows. A precut blank 109 -
of material comprising a pair of fibrous skins 101 and
102 and a core material 103 may be conveyed, while --
supported by belt 108, into a press assembly 104, such
as that illustrated in the cross-sectional views of -
FIGS. 5 and 6. Belt 10~ is preferably constructed of a
35 relatively heat-conductive (non-insulative~ material. --
An example of such a material is a thin Teflon-coated
glass belt which is durable and has good release
characteristics. Press assembly 104 is equipped with an
. . .
Jo
~2~2~3~
- I - LFM-7342
upper platen 105 which, as illustrated in the figures,
is provided with embossing plate 106. Lower platen 107
supports belt 108, which in turn supports blank 109. ::
When press 104 is closed, die points 110 groove-mold -
5 blank 109 such that the blank is grooved along groove -
lines 111, as illustrated in FIG. 6, to provide an
unsectioned board which, for example, can have the
appearance illustrated in FIG. 9. During the pressing
operation, platen edge surface 112 provides an angled
edge, platen regular edge detail surfaces 113 and 114
impart a decorative and functional edge detail to blank
109, and embossing plate 106 imparts surface detail.
This process also causes upper skin 101 to be stretched ---
downwardly toward groove line 111.
The purpose of grooving the board is to define '-
the outer dimensions of the finished product and to
provide lines of weakness along which trim scrap 115 and
individual board pieces may be cleanly and efficiently ---
separated from one another. Although grooving can be ---
20 carried out such that each piece is die cut, it has been -
found advantageous not to die cut the blank by grooving -
through its entire thickness. Premature separation of -::
the trim scrap from the board, such as by die cutting,
is inconvenient because loose pieces of scrap cannot be
easily separated from the finished product as they
emerge from the press. In addition, special problems l-:
are associated with such die cutting. As one example, --
die cutting cannot be carried out while the blank rests ---
on belt 108 because the belt would be damaged by die -
30 points 110. In conventional methods, caulk plates might -
be used to facilitate such die cutting; however, caulk t,',,',
plates are not particularly desirable because they are -:
expensive, caulk elevators are required which add to the --
expense, and caulk operations build inherent delays into
35 the production process. Although a keelhauls system t.-:
might be used as an alternative, it also is not --
particularly satisfactory because the blank must have --
sufficient strength to hold together. Improved strength
.....
. . .
. . .
":,"~ I=
~23~39~ 1
- 25 -- LFM-7342
can usually be attained by increasing the degree of
intermediate curing, or by increasing binder levels,
basis weights, or thickness; however, with certain
binders, increasing the intermediate cure leads to a
5 reduction in the embossibility of the board, and -I
increasing the materials used in the board is
undesirable from an economic standpoint. Accordingly, --
it is preferable not to die cut the board. -
When groove-equalizing the board, it is also
preferred that groove lines 111 not be too shallowly
groove molded. Shallow grooving leads to irregular
separation of the edge scrap such that the visual -
appearance of the edge is unacceptable. It has been
found preferable to groove-mold the board such that the
15 grooved material remaining along line 111 is from about I:
0.015 to about 0.030 inch thick. At less than about ,-
0.015 inch, the grooved line breaks of its own accord,
and above about 0.030 inch, the edge definition - -
deteriorates.
Another parameter which affects the quality of
the edge detail is the width of the blank which resides -
along both sides of the groove line. Cross-blank groove --
molding is normally achieved without difficulty because
substantial widths of material lie on both sides of the ---
25 grooving line, and the stresses induced in the blank by -
die points 110 are approximately equal on both sides of
the groove line. However, difficulty can be encountered
when groove molding along the edge of a blank. FIG. 6
illustrates edge trim sections 115 which are ultimately -
30 discarded as scrap. If trim sections 115 are about 4 -
inches or more in width, straight grooving and clean -
separation will result. However, if these sections are
only 1 to 2 inches in width, the material which :
constitutes the trim section tends to move laterally.
35 Such movement induces tearing of the skins along groove ,-:
line 111 and results in poor edge detail. The use of
wide edge trim sections is not desirable because wide
scrap strips produce excess scrap, which results in
I:
.....
........ ................................... .
.................. .............
- .. , .. - . -- .,
~32734
- 26 - LFM-7342
increased costs. Fortunately, however, lateral movement
can be avoided by a process that is referred to herein
as outboard clamping.
The outboard portion of upper platen 105 which -
5 contacts trim section 115 can be made such that it is -I
thicker than the inboard portion of upper platen 105.
This is illustrated in FIG. 6 wherein the outboard -
portion 125 of upper platen 105 could be made to a -
thickness having dimension A which, as illustrated by
the dashed line, is somewhat greater than the inboard
thickness B. During the pressing step, the thicker
outboard portion of the platen would tend to hold trim
section 115 in place; thus, lateral movement could not -
occur and good edge detail could be achieved. It has -
been found for the examples illustrated herein that a
differential thickness of about 0.060 inch between
dimensions A and B will provide good results. However, -
this difference may be varied as the artisan desires
depending on the characteristics of the board.
The angle of the board edge which may be -
provided using the embossing process described herein is
variable; however, practical considerations suggest that
this angle (116) will preferably vary from about 45
degrees to about 76 degrees (FIGS. 7 and 8). With
angles greater than about 76 degrees, frictional binding
of die points 110 against blank 109 becomes important
whereas, at angles less than 45 degrees, edge point 117
becomes increasingly fragile and subject to damage. For
the examples illustrated herein, angles on the order of
30 about 70 degrees have been especially preferred because ---
of the way in which the edge performed during damage -
resistance tests. Thus, for example, when the edge of a -
ceiling board was impacted at point 117 with a foreign ---
object, chips tended to be removed from the back of the ,-
board rather than from the vertical face of the edge.
Despite the loss of these chips, which comprised a --
portion of core 103 and lower's kin 102, the damaged -
boards nevertheless maintained good visual appearance ,--
. . .
....
.................... .... ............... ............... ......................... . . ... .
.... ...... . ........... . ..... ......... ....
1~32734
- 27 LFM-7342
when installed in a ceiling grid system.
The compositions of the boards produced using
the grooving and embossing processes disclosed herein
will usually vary from those which are not made using -I
5 such processes. As indicated above, grooving and ---
embossing cause a stretching of the upper skin because `
they cause an increase in surface area, and the skin is --
forced to accommodate itself to the expanded contour.
For that reason, a relatively thick upper skin is
required in comparison to the lower skin. Of course, if
surface detail or embossing is provided to the back :-~
surface of the board, such as through the use of a
patterned belt, appropriate adjustments in thickness -
might also be required for the lower skin.
An increase in surface thickness of the board
will usually mandate a reduction in core material so as
to maintain the basis weight of the board within -
acceptable limits. Furthermore, if the board will not --
be punched and is intended to have good acoustical -
character, it is preferable that it be of fairly light
construction. Thus, a greater than normal reduction of
core material might be necessary. I:
When selecting binders to use in preparing
grooved and embossed products, care must be taken to -
ensure that the binder will be amenable to the embossing
procedures. Resins which are thermosettable, or which ---
can be made to assume a rigid shape under the pressing
conditions, are preferred. Examples of such resins are --
starch (free flowing or pre-gelled), melamine-formal- -
Dodd resins, finlike resins, urea-formaldehyde
resins, epoxy resins, polyester resins, and the like.
Thermoplastic resins can be used with difficulty, but
are not preferred because they cannot assume a rigid
shape in a heated press.
These and a variety of other structures having
diverse characteristics can be produced according to the
present invention. Illustrations of preferred
embodiments are set forth in the examples. Other -
r
, .. ... ... ... .. ... .... . ... ..... .... ...... .............. .. ............................ .......... ... .......
1~3Z73~
- 28 - LFM-7342
advantages and attributes of the present invention will
become even more apparent by reference to these examples.
EXAMPLES
Example I --
This example illustrates the preparation of a
product comprising about I mineral wool and 13%
powdered finlike binder, the resulting product having a -
thickness of about 1.5 inches and a density of about 6
pounds per cubic foot. The product was prepared using -
10 35 apparatus having dual mat-forming zones such as those ---
illustrated in FIG. 4. Identification numbers refer to
the numbers used in the figures. The lower mat-forming -
zone 83 used for this and subsequent examples was -
constructed of plexiglass such that the distance between I-
15 nip opening 47 and back panel 67 was about 109 inches, L-----
the zone width as measured between side panels 68 and 69
was about 26 inches, and the height as measured
vertically between wire 45 and the center point of
licker in roll 42 was about 42 inches. The angle of nip
opening 47 was about 25 degrees. Upper mat-forming zone
84 had a distance between nip opening 47 and back panel -
67 of about 84 inches, the width and the height being I-
about the same as for mat-forming zone 83. The angle at
nip opening 47 was about 48 degrees. Lo---
For each mat-forming zone 83 and 84, mineral I------
wool fibers were separated and fed onto conveyor 30 at a ::
rate of 7.56 pounds per minute using a VectrofloO
gravimetric feeding device. The finlike resin was fed -
onto the fibers through station 32 at a rate of 2.25
pounds per minute. This material was mixed together
with fluffing roll 33 and fed to the respective
fiberizing devices 34. l--
The wires in the respective chambers were
converged at approximately 10 feet per minute and air r
35 was introduced to the respective chambers at a volume of ---
approximately 5,000 cubic feet per minute while being
exhausted through forming wires 45 and 46. The pressure
inside each forming chamber was approximately 2.1 inches `
73~
- I - LFM-7342
of water below atmospheric pressure, measured using a
Dyer gauge. In the lower forming chamber, approximately
90% of the entraining air was withdrawn through bottom ;
forming wire 45, the majority of this air being ---
5 withdrawn through exhaust means 62. In the upper --
forming chamber, approximately 60% of the air was --
exhausted through upper forming wire 46, no attempt
being made to variably exhaust the air. Vanes 77 were --
oscillated within each aperture 44 at approximately 30
lo cycles per minute.
The matted materials were converged at nip
openings 47 and consolidated in consolidation zones 48. . -
Immediately prior to exiting from consolidation zones --
48, the composite materials were simultaneously tamped
15 using tamping devices 50 and exposed to anti-static -
devices 51. Tamping devices 50 were adjusted to strike --
the back side of wires 46 approximately 30 times per -
minute, causing the mats to be alternately compressed
and released. These devices assisted in minimizing ::
20 mechanical cling. Anti-static devices 51 were -
conventional alpha particle emitters which removed the
charges from the fibrous mats and minimized static
cling. When these devices were used separately or not
used at all, full separation of the matted materials
25 from the wires was not obtained. The simultaneous use --
of these devices, however, has given good separation, r.'.'.. '
resulting in high quality products.
The individual webs emerging from mat-forming
zones 83 and 84 were converged and recompressed using
30 recompression assembly 98. This device was adjusted --
such that the nip opening contacted the consolidated web or-,"
very lightly. The consolidated material was then passed
into a through convection dryer (TED) oven and exposed i-
to air heated at about 400 F. for approximately three i;::
minutes. During this exposure time, the resinous binder
melted and substantially cured. The distance between
the pressure conveyors of the TED oven was approximately -
1.56 inches; therefore, when the board emerged from the j'
."',.,''.
.,: -
:,:: . ..... ............. ...................... ........ .... ... ......................... ..
.......... .. ......................... ........... ..
-,, ,,. .,,,,, ,,. .,:: ,::.. . . .. .. ... ...... . . . . . .... ... ..
1~32734
- 30 - LFM-7342
TED oven in a somewhat plastic condition, it was post-
gauged and cooled. Post gauging adjusted the thickness
of the board to about 1.5 inches and concurrent cooling
with ambient air reduced the board temperature to --
5 somewhat less than 250 F. Product produced in this -
fashion without the use of a post-gauging device has --
been found to have a thickness variation of + 0.04 ---
inches, whereas material produced using the post-gauging --
device has been shown to have a thickness variation of +
10 0.01 inch. :
The acoustical performance of products formed
in this manner was determined by measuring the noise -
isolation class (NIX) and the noise reduction
coefficient (NRC) of the boards. For one representative -
product, an NIX value of 20 was measured according to
PBS-C.2, and an NRC of 95 was measured according to
ASTM C-423-81 using E-400 mounting. Thus, the product -
was suitable for a variety of high performance
acoustical applications.
Example II -
This example illustrates the preparation of a
sandwich-like product having an overall composition as ---
follows:
Weight Percent
25 Ingredient (solids basis i-
Mineral wool 24.21
Powdered finlike binder 1.82 -
Expanded puerility 64.35
Liquid finlike resin 9.62 ---
....
The outer layers comprised 93~ mineral wool and 7%
powdered finlike binder whereas the core mixture
comprised 87% expanded puerility and 13% liquid finlike --
resin.
Mineral wool fibers were fed onto conveyor 30
of upper and lower forming systems 83 and 84 at a rate
of 2.47 pounds per minute. powdered finlike resin was
then fed onto conveyor 30 via station 32 at a rate of
...
.............. . ..... ...................................................
: " :,-, """":,: ".,:.".~
~3273~
- 31 - LFM-7342
0.185 pounds per minute. This material was mixed
together with fluffing roll 33 and fed to fiberizing
devices 34 of each mat-forming zone. Except as noted
below, the operating parameters were the same as those
5 set forth in Example I. -
The mineral wool binder compositions were fed --
into the respective mat-forming zones and felled onto :-
pheromones wires 45 and 46 essentially as described in
Example I. In this case, however, the air was exhausted
10 at different rates through the pheromones wires in the
lower chamber; thus, approximately 75~ of the air was
withdrawn through bottom forming wire 45 of zone 83 and
approximately 25~ was withdrawn through top forming
wire 46. The static pressure in each of these chambers
15 was approximately 1.8 inches of water below atmospheric
pressure, measured using a Dyer gauge. ::
The mats were converged at the respective nip
openings 47, consolidated in compression zones 48, -treated with tamping devices 50 and anti-static devices ::
20 51, and then conveyed toward recompression rolls 98.
After the lower mat had been transferred onto conveyor
90, a mixture of 23% liquid finlike resin and 77% r:::expanded puerility was deposited via addition station 91 L
onto the lower mat at a rate of 0.87 pounds per square -25 foot wet basis). The core mixture was leveled with -
screwed 93, combined with the upper mat 94, and
consolidated using recompression rolls 98. The height -
of the recompression rolls at the incoming point was
approximately 1.3 inches above conveyor 98 whereas at
30 opening nip 99 the height was about 0.54 inches. This i-
induced the emerging material to be extruded through the ,-
narrow nip opening. The thickness of the resulting :
recompressed composite was approximately 700 miss.
Recompression served to impart to the -
resulting uncured board sufficient strength and edge
definition such that the board could be conveyed through
succeeding preheating and curing operations without loss
of puerility from the core or damage to the composite. -
'I"".
. .
: .:.: .: - -: - .. . , . . - .
1~273~
- 32 - LOMB
After recompression the board was transferred to a
TED device such as that illustrated in FIG. l; however,
the upper compression means were not used in preparing
the cored product. The purpose of the TED device was to
5 preheat the cored product with a downward flow of air, --
thus causing substantial drying and curing of the core
mixture while leaving the skins essentially uncured. -
Accordingly, the temperature of the air in the TED oven
remained below 300 F, a temperature at which the skin :-
. - -
binder did not cure. Approximately a 2-minute period
was used for preheating.
Following the preheating step, the board was
cut into blanks and fed by a speed-up conveyor into a
flatbed press. Because of the desired thickness of --
about 0.63 inch or the product, appropriate stops were
used in the press to ensure that excessive compression -
did not occur. The final curing temperature was 450
...:..
F., although variations between 350 F. and 550 F. -:
could be used. Dwell times in the press varied from
20 about 15 seconds to about 15 minutes, although a I-
compression time of 1 minute and 30 seconds gave good
results at 450 F. Optionally, a band press could also E-
have been used for the final curing and pressing steps. [
The resulting board had an overall thickness I-:
of 0.63 inch and a density of 19.8 pounds per cubic
foot. The approximate thickness of each of the upper
and lower skins was 0.04 inch and the core thickness was
0.55 inch. The approximate density of the skin was 34.3
pounds per cubic foot whereas the core density was
30 approximately 15.7 pounds per cubic foot.
Example III :
This example illustrates the preparation of an
embossed sandwich-like building board. The product was
prepared in exactly the same manner described in Example --
35 II until the point where the uncured board emerged from
recompression rolls 98. In this case, the material was --
conveyed into the TED device and air was passed through
the board from the bottom to the top. Because of the -
.....
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, I,, .. , ,. , - ,, .. , , , , ., . .. , .. . " .. ,, .. , .. ,,,, . .. .. , " . .. .. ... . . . .. .........
1~32 ~34
- 33 - LFM-7342
reverse flow, the upper compression means was adjusted
to slightly touch the upper surface of the board to
prevent it from lifting or buckling due to the upward
pressure of the air stream. As a result of this
5 treatment, curing occurred from the bottom of the board r''."'
upwardly and the conditions were adjusted such that the I--
curing was effected to within 1/16-1/4 inch of the upper ,-
surface of the core material.
Following the preheating step, the board was
10 cut into blanks and fed into a flat bed press, the upper ::
platen of the press being equipped with an embossing
plate. The pressure was adjusted such that the
embossing plate penetrated only the upper, uncured
region of the board. As described for Example II, a
15 temperature of 450 F. was utilized for a dwell time of
1 minute 30 seconds. The density and basis weight I:
values were essentially the same as for the product of Jo
Example II.
Example IV -
L-:-:
This example illustrates the preparation of a
sandwich-like product having a thin, high-density,
moisture-resistant interior. The overall composition I:
: :.
was as follows: l
Weight Percent E:
25 Ingredients (solids basis)
Mineral wool 34.14
Powdered finlike binder 6.10 -
Cement grade puerility 50.76
Urea formaldehyde resin 9.00
.....
The outer layers comprised 85% mineral wool and 15%
powdered finlike binder whereas the core mixture
comprised 85% cement grade puerility and 15% urea
formaldehyde resin.
The board was prepared essentially as
35 described in Example II; however, because the desired r,:.,',
final gauge was 0.1875 inch the stops in the precom-
presser were set at 0.1795 inch. The resulting board
......................... .. .................................................... ....... . .. .... . ........... ............. ............................. .. .....
.................... .... .. . .
3~7~3~
- 34 - LFM-7342
had a density of 42 pounds per cubic foot and a basis
weight of 0.656 pounds per square foot. The weight of
the outer skins was 0.264 pounds per square foot.
Example V -:-
This example illustrates the preparation of a --
damage resistant board containing fibrous wood material. -
The overall composition of the board was as follows:
Weight Percent
Ingredients (solids basis) --
10 Mineral wool 22.17
Powdered finlike binder 3.87
Expanded puerility 48.10
debarked aspen wood fiber I:
Liquid finlike resin 14.78
This board was produced in the same fashion described in
Example II to give a product having a thickness of 0.625 ,-
inch and a density of 19.8 pounds per cubic foot. The
total weight of the outer skins was 0.269 pounds per -
square foot. The presence of the wood fiber in this -
product had the effect of increasing the board's
toughness while reducing the effects of damaging impact.
Example VI
This example, in which two alternative
modifications are described, further illustrates the ::
25 technique of sequential curing. The basic procedure was -
comparable to that used in Example II except that (13 --
the finlike resin contained no hexamethylenetetramine
curing agent and (2) the previously used core binder was
replaced by a starch powder.
The overall composition of the board, --
calculated on a dry basis, was as follows:
Weight Percent
Ingredient (solids basis)
Mineral wool 24.21 -:-
35 Powdered novalac finlike binder
plus hexamethylenetetramine 1.82 -I
Expanded puerility 64.35
Powdered starch binder 9.62
, .. .. ",, .. , .,.,, ., ". ,,,, .. " .. , .. ,, .. .... , .. ,, ., .. ... , .. , " ........ .......... ..... ... ... ...
1~3~2~73g~
- 35 - LFM-7342
The outer layers comprised 93% mineral wool
and 7% binder, based on the above proportions of the
ingredients, whereas the dry core mixture comprised 87%
expanded puerility and 13% powdered starch.
The upper and lower skins were produced as
described in Example II, except that the powdered binder --
was added at a rate of 0.17 pounds per minute due to the
absence of the curing agent. The weight of the upper
and lower skins was about 55 grams per square foot (dry -
basis). Prior to adding the core mixture, it was
moistened with water at a level of 19% based on the
weight of the wet mixture. The moistened core mixture
was then added via core deposition station 91 at a level I-
of 0.98 pounds per square foot, the difference from the -
quantity set forth in Example II being due to the added
moisture. -
After the added material was leveled with
screwed 93, the composite materials were consolidated --
with the upper mat using recompression rolls 98. The --
20 composite material was then transferred to a TED device -
which, unlike the device in Example II, was provided
with a steaming apparatus. The steaming apparatus was `
located at the entrance of the TED device and consisted
of a steam manifold located above the board and a vacuum --
device located beneath the board, under the TED conveyor.
As the board passed into the TED oven, the steaming
device was used to draw steam into the board at a rate
sufficient to raise the temperature of the water in the --
core mixture above 180 F., thus causing the starch to
30 gel. The board proceeded through the TED device where -
the core was dried and preheated in the usual manner. -
However, in this instance, it was possible to use
temperatures in excess of 300 F. because the binder in -
the skins did not contain the curing agent.
Following the golfing and drying steps, the -I
board was cut into blanks and fed into a spray booth. --
In this booth, a paint solution comprising 10% -
hexamethylenetetramine was applied to the upper and -
. . .
, .. . .. .... . .. .. .. .. . . . . .. . . . .. ..... .. . . . .
~i~32734
- 36 - LFM-7342
lower faces of the board at a rate of 6 grams per square
foot. The board was thin fed by a speed up conveyor to
a flatbed press and cured as described in Example II.
Under the action of the press, the hexamethylene-
tetramine degraded to liberate the formaldehyde curing
agent, thereby curing the resin. The board was then --I
punched with needles having diameters of 0.100- and --
inch and was spray painted with an aqueous paint
at a level of 11 grams per square foot. The physical
characteristics of the board were essentially the same
as those measured for the product of Example II. The
NRC rating of the punched board was 55. It is noted
that the densities of acceptable products obtained using
the above formulations will usually vary from about 15.5
lo to about 23 pounds per cubic foot. -
Embossed products may also be prepared in the I-:
same manner and they provide the added advantage of --
avoiding the partial procuring step as set forth in
Example III. Thus, when the upper and lower skins are
20 cured in the presence of the hexamethylenetetramine -
solution, the water which vaporizes softens the starch
core binder, thereby permitting it to be reformed in a
desirable embossed shape.
Example VII -
::.
This example illustrates a preferred groove
molded and embossed board which was not punched, yet had -
a high NRC value. -
The composition of the hoard was as follows:
....:
Weight Percent
30 Ingredient (solids basis)
. .
Mineral wool 41.8 --
Powdered novalac finlike binder -
plus hexamethylenetetramine 5.2 -
Expanded puerility 42.4
35 Powdered starch binder ' 10.6 -I
....
'
123~734
- 37 - LFM-7342
As compared to the product of Example VI, the
outer layers comprised 89% mineral wool and 11% binder
whereas the core material comprised 80% expanded puerility
and 20% binder. -
The board was produced approximately according --
to the process steps of Example VI; however, the upper
and lower skins had basis weights of 110 and 55 grams
per square foot (dry basis), respectively. Following -
the cutting of the board into blanks, the upper surface
10 of each blank was sprayed with a primer which contained
the hexamethylenetetramine curing agent. The blanks
were then fed into a spray booth where a 10% solution of
hexamethylenetetramine was applied to the back face of
the blank at a rate of 6 grams per square foot. Next,
the blanks were fed into a flat-bed press equipped with
a grooving platen and an embossing plate, and each blank -
was grooved to leave a groove line thickness along lines
111 of 0.02 inch. The edge angle was about 70 degrees
and the appearance of the groove molded board
20 corresponded to that illustrated in FIG. 9 where 121, :--
122, 123 and 124 are the unseparated board segments. ---
Upon completion of the curing process (500 F --
for 45 seconds), the board was cooled, separated into
individual boards and spray painted with an aqueous
25 latex finish paint at a rate of 16 grams per square foot -
(dry weight). --
The resulting board had a deep, clear
embossing pattern but also had an NRC value of 65. Its
basis weight was 0.75 pounds per square foot, its :
30 density was 15.5 pounds per cubic foot, and the board -I
thickness in the unembossed areas was 0.58 inch. --
This invention is not restricted solely to the
descriptions and illustrations provided above, but
encompasses all modifications envisaged by the following
claims.
....
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