Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF IMPREGNATING
lC MINERAL FIBRR INSULATION
BATT WITH EXTRUDED SYNTHETIC FIBERS
This invention relates to a method of impregnating
at least one surface of a mineral fiber (e.g. fiberglass)
batt with extruded synthetic fibers. More particularly,
this invention relates to a method (and corresponding
apparatus and product) of extruding fibers from a-
synthetic resin (e.g. ethyl vinyl acetate) onto at least
one surface of an insulation batt so that the extruded
fibers lock onto mineral fibers proxirnate the batt
surface so as to impregnate the batt.
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BACKGROUND OF THE INVENTION
Mineral fiber insulation batts coated with kraft
paper and the like are old and well-known. Examples of
mineral fiber include fiberglass, rock wool, etc.
- 5 Typically, the base mineral fiber insulation batt is
processed along an endless conveyor system and a sheet(s)
of kraft paper is adhered to at least one surface of the
insulation batt. The resulting batts, coated with kraft
paper, are typically used for insulatlng vertical wall
cavities and the like.
Unfortunately, such batts suffer from the following
problems: (i) they lack durability and are susceptible
to damage such as tearing at job sites; (ii) they tend to
allow dust to be generated therefrom; (iii) paper burns;
(iv) their aesthetic appearance is le.,s than desirable to
many in the trade; and (v) cost of paper. Accordl-ngly,
there exists a need in the art to improve upon the above-
listed drawbacks of kraft paper coated mineral fiber
batts.
It is also known to apply polyethy]ene and
polypropylene films to batts. For ex~mple, see U S.
Patent Nos. 5,318,644; 5,362,539; and 5,27-7,955.
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U.S. Patent No. 5,362,539 discloses a polyethylene
or polypropylene film applied to an insulation batt.
Either an adhesive, Velcro~, or heat sealing is used to
adhere the film to the mineral fiber core.
Unfortunately, with respect to use of an adhesive or
Velcro~ to attach the film to the core, these represent
multi-step adhering processes for coating the batt with
film, which are both undesirable and inefficient.
Additionally, such batts are susceptible to cold-crack at
temperatures which range down to about -65~ F. Cold-
crack often occurs when hot melt adhesives and the like
are utilized to adhere laminants together, this often
resulting in the laminates prematurely separating or
delaminating. With respect to heat sealing the
polyethylene or polypropylene to the mineral fiber core,
this has been found by the instant inventors to represent
a less than sufficient attachment of the film to the
core. For example, the instant inventors have found that
when commercial attempts to laminate polymer films to a
fiberglass batt have been made, the surface strength of
the lamination is sometimes incapable of maintaining the
weight of the fiberglass in certain instances and often
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results in de-lamination. Furthermore, complex equipment
is required to manufacture such poly film-coated batts,
which is not cost effective.
U.S. Patent No. 5,277,955 discloses a mineral fiber
batt to which a polyethylene layer is applied. The
polyethylene layer may be heated for the purpose of
joining the film to the mineral batt. As discussed
above, and as apparently recognized in the '955 patent,
this may not result in an adequate attachment of the film
to the batt. Accordingly, the disclosure of the '955
patent suffers from the same problems as those discussed
above regarding the '539 patent.
U.S. Patent No. 5,318,644 discloses a method and
apparatus for making an insulation assembly, wherein a
pair of polyethylene layers are utilized to encapsulate a
mineral fiber batt. Unfortunately, the system of the '644
patent suffers from the same problems that are discussed
above regarding the '955 and '539 patents.
In view of the above, it will be clear to those of
skill in the art that there exists a need in the art for
an improved mineral fiber insulation batt, and
corresponding method and apparatus for manufacturing
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same, which is efficient and cost effective to
manufacture, is easy to handle, is less susceptible to
cold-crack, it is aesthetically attractive, and reduces
generation of dust. It is a purpose of this invention to
fulfill the above-described needs in the art as well as
other needs which will become apparent to the skilled
artisan upon review of this disclosure.
SUMMARY OF THE INVENTION
Generally speaking, this invention fulfills the
above-described needs in the art by providing a method of
applying extruded synthetic fibers to at least one
surface of a fiber batt, the method comprising the steps
of:
conveying the batt via a conveyor in a conveying
direction, the batt including a top major surface; a
bottom major surface, and first and second opposing edge
surfaces;
providing an extrusion head adjacent and directed at
one of said surfaces of the batt being conveyed so that
said surface of the batt passes adjacent t:he extrusion
head during said conveying step, said ext~-usion head
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including an extrusion orifice through which molten
synthetic material is forced so as to form extruded
synthetic fibers;
extruding the synthetic fibers from said extrusion
head and directing the extruded fibers onto said surface
of the batt being conveyed via the conveyor;
in the extrusion head, directing a plurality of
separate air streams toward the fiber being extruded from
the extrusion orifice in order to break up the extruded
fiber into a plurality of different segments or fibers,
and cause the different segments to be directed toward
the surface of the batt; and
allowing the extruded fibers to cool or cure on the
surface of the batt so that during the cooling the
extruded fibers interlock with the fibers on the batt.
In certain embodiments, the extruded fibers are
applied to the batt on a surface thereof in an amount of
from about 1.2 to 3.5 gms/ft2.
In certain preferred embodiments, the synthetic
material which is extruded includes ethyl vinyl acetate
(EVA).
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In certain preferred embodiments, the batt is a
mineral fiber insulat.ion batt, such as a fiberglass
insulation batt.
This invention further fulfills the above-described
needs in the art by providing a method of directing
extruded synthetic fi.bers (e.g. including EVA) toward at
least one surface of a mineral fiber batt, the method
comprising the steps of:
conveying first and second mineral fiber insulation
batts along a substantially planar conveyor, each of the
first and second batt:s including first and second major
surfaces and first and second opposing edge surfaces;
providing an elongated substantially horizontally
aligned member which is positioned over top of the
conveyor and over top of at least the second batt;
providing a first extrusion head proximate and
directed at an edge surface of the first batt and a
second extrusion head proximate and directed at an edge
surface of the second batt;
causing the second batt to pass over top of the
elongated member and the first batt to pass underneath of
the elongated member; and
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directing extruded synthetic fibers from the first
extrusion head toward the edge surface of the first batt,
and directing extruded synthetic fibers from the second
extrusion head toward the edge surface of the second batt
when the first batt is passing underneath of the
elongated member and the second batt is passing over top
of the elongated member.
In certain preferred embodiments, the first
extrusion head directed toward the edge surface of the
first batt is substantially parallel to and located at a
different elevation than the second extrusion head which
is directed at the edge surface of the second batt.
IN THE DR~WINGS
Figure 1 is a perspective view illustrating an
apparatus and method of making a mineral fiber batt
according to an embodiment of this invention.
Figure 2 is a side cross-sectional view of an
extrusion head which directs extruded polymer-based
synthetic fibers toward a surface of a mineral fiber batt
in the Figure 1 apparatus/method.
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Figure 3 is a partial perspective view illustrating
certain extrusion heads of Figures 1-2 applying extruded
polymer based fibers to different edge surfaces of the
batts in the Figure 1-2 embodiment of this invention.
Figure 4 is a perspective view illustrating a
plurality of the Figures 1-2 extrusion heads which are
placed in a row adjacent the top and/or bottom major
surface(s) of the batt(s).
Figure 5 is a perspective view illustrating how the
air jets located proximate the extrusion outlet of an
extrusion head according to the Figure 1-4 embodiment
break up the fibers and cause same to fall into an
insipid spin as they are directed toward the moving
batts.
Figure 6 is a perspective view illustrating how a
fiber from one of the extrusion heads of Figures ~-5 is
directed toward and lmpregnates the surface of a mineral
fiber batt, as the extruded fiber locks onto mineral
fibers adjacent the batt's surface during curing or
cooling of the extru(~ed fiber.
Figure 7 is a partial top elevational view
illustrating extruded ethyl vinyl ace~ate (EVA) extruded
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fibers impregnating a major surface of a fiberglass
mineral batt.
DETAILED DESCRIPTION OF
CERTAIN EMBODIMENTS OF THIS INVENTION
Referring now more particularly to the accompanying
drawings in which like reference numerals indicate like
parts throughout the several views.
Figure l is a perspective view illustrating an
apparatus and method for manufacturing mineral fiber
(e.g. fiberglass~ binder-inclusive batts which are
impregnated with extruded synthetic polymeric inclusive
fibers (e.g. fiber including ethyl vinyl acetate or EVA)
on at least one surface thereof. In the Figure 1
embodiment, each of the top major surface 1, edge surface
3, and opposiny edge surface 5 of each batt 18 is
impregnated with fibers that are extruded from ext-rusion
heads 2, 9, and 11. As shown, a plurality of extrusion
heads 2 are disposed over top of mineral fiber batts 18
that are being conveyed by planar conveyor belt 13 in
direction 15, this row 7 of extrusion heads 2 being
oriented such that extruded fihers 17 that include a
synthetic material (e.g. EvA) are extruded from heads 2
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and are blown and fall toward the top major surfaces 1 of
the numerous batt portions 18 being forwarded along belt
13.
Meanwhile, extrusion heads 11 impregnate edge
surfaces 5 of batts 18 with similar extruded synthetic
fibers while extrusion heads 9 impregnate opposing edge
surfaces 3 of the batts with similar synthetic extruded
fibers (e.g. fibers that include EVA or the like). In
certain embodiments, it is desirable to provide another
row of extrusion heads 2 below the lower major surface of
the batts 18, at a position opposite upper row 7, so that
each of the top and bottom major surfaces of batts 18, as
well as the two edge surfaces 3 and 5, are impregnated
with extruded synthetic fibers. Optionally, when batts
18 are cut up lengthwise, the newly formed edge surfaces
may be impregnated in a similar manner so that all six
surfaces are impregnated with the extruded fibers.
The result of impregnating at least one surface of
mineral fiber batts 18 with extruded fibers 17 including
a synthetic material such as ethyl vinyl acetate (EVA) is
a batt having a synthetic outer cover that is vapor
permeable and non-allergenic to workers hclndling or using
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the product. Furthermore, loose insulation fibers, such
as glass fibers, that may sometimes create dust from the
batt, are trapped within the batt by the extruded
covering system beneath its synthetic web so as to
eliminate dust-inclusive environments. The extruded
synthetic fiber impregnation of the batts will resist
water permeation such that any condensation that may be
created will not become entrapped within the batt, and
will be permitted to evaporate via standard wall
ventilation (this will eliminate fungal and bacterial
growth and help prevent sick-building and sick home
syndrome). Other advantages of the inventive batt which
include the extruded synthetic inclusive fiber covering
are: improved handling capability, non-absorbent,
resistant to mildew and rot, deterrent of bacterial and
fungal growth, deterrent of bugs and insects, helps
maintain batts and prevents them from sagging and packing
under vibration load, aesthetically pleasing, and allows
vapor permeability so that insulation batts (e.g. in
rolls) can collapse or be compressed during shipment.
Still further, the improved product assists in providing
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improved acoustic or sound insulation, especially in duct
applications and the like.
As illustrated in Figure 1, the apparatus and method
includes slitting area 15 where the mineral fiber
insulation being conveyed along belt 13 transferred from
one large batt into a plurality of smaller batts 18, as
the large batt is slit along lines 16 in order to provide
the plurality of separate and independent batts 18 which
are conveyed along the belt 13. Exemplary fiberglass
insulation batts according to certain embodiments of this
invention have a density of from about 0.25 to 10.0
lb./ft3., preferably from about 0.5 to 2.5 lb./ft3. These
batts typically will have an R-value of from about 2.5 to
4.0 per inch of batt thickness, preferably from about 3.0
to 3.3 per inch thickness.
Following slitting area 15, row 7 of extrusion heads
2 directs extruded fibers 17 (e.g. fibers including EVA)
toward the top major surface 1 of the plurality of batts
18 which are being forwarded along the belt. Row 7 of
extrusion heads 2 is in communication with pressurized
heated air supply line 20 and heated line 22 which
supplies the row 7 oi heads 2 with molten s~nthetlc
14
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material, such as EVA, to be extruded by head 2 onto the
top surface 1 of batts 18.
Following the deposition of the extruded synthetic
fibers 17 onto the top surface of batts 18, every other
or alternate batt (e.g. either the odd numbered or even
numbered batts) is caused to be conveyed or arced over
top of rigid elongated eliminate 23 so that the opposing
edge surfaces 3, 5 of each batt 18 may be exposed and
impregnated with extruded synthetic fibers directed at
the respective edge surfaces from extrusion heads 9 and
11. For example, member 23 may include a rigid bar which
extends across and above belt 13, and may be supplemented
by pressurized airline 20 which extends across belt 13,
and heated molten resin line 24 which supplies the molten
material to be extruded to the various heads 9 and 11
from unit 25. Optionally, member 23 may simply be made
up of conduits 20 and 24.
Generally, unit 25 represents a synthetic material
preparation and pumping system where the synthetic
material to be extruded is initially loaded or input,
this material taking the form of pellets, blocks, chunks,
chips, or the like as is known in the trade. Unit 25
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forward the molten material to be extruded to heads 2, 9,
and 11.
Following the impregnation of the opposing edge
surfaces 35 of each batt 18 with the extruded synthetic
fibers 17 by heads 9 and 11, the batts 18 which had
passed over top of member 23 fall back to the upper
surface of conveyor belt 13 so as to again be
substantially co-planar with batts 18 that had passed
underneath of member 23. The batts 18 which are conveyed
by belt over top of conduits 20 and 24 form arch-like
profiles over same.
Downstream of member 23 and heads 9, 11 are a
plurality of disk-shaped separators (which may be cooled
in certain embodiments) which are positioned along lines
16 in between the different batts 18. These separators
30 function to separate and prevent or delaminate-any
adhesion which may have taken place between adjacent edge
surfaces 35 of immediately adjacent batts as a result of
the still-warm extruded fibers which were applied by
heads 9 and 11 to these edges 3, 5. In other words,
separators 30 keep the batts from sticking together along
their respective edge surfaces 3, ',.
16
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According to certain alternative embodiments, the
edges 3, S of batts 18 may be impregnated with the
extruded fibers after the batts have been chopped up or
cut lengthwise, instead of prior to this event as shown
in Figure 1. Still further, it will be recognized by
those of skill in the art that the application of the
extruded fibers to the batt surface(s) may be carried out
on-line as illustrated in the drawings herein, or
alternatively off-line although this latter option may
not be cost effective.
Figure 2 is a cross-sectional view of one of the
extrusion heads illustrated in Figure 1. The Figure 2
head may be, for example, one of extrusion heads 2
provided in the row 7 across the top major surface 1 of
the batts. Extrusion heads 9 and 11 are the same as head
2 illustrated in Figure 2, except that heads 9 and 11
have their air and heat conduits located in different
locations.
As illustrated in Eigure 2, each extrusion head 2
includes elongated heating element 33, elongated air
conduit chamber 35, chamber 37 which permits molten
synthetic material (e.g. including EVA) to be fed through
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the head and extruded therefrom, annular EVA feed chamber
39 which surrounds one end of elongated needle valve 41
and is in communication with chamber 37, annular air
chamber 43 which is selectively pressurized in order to
selectively open and shut needle valve 41, biasing spring
45 which functions to bias shut needle valve 41 when air
chamber 43 is not pressurized beyond a predetermined
pressure threshold, air feed conduit 47 for communicating
heated pressurized air to a plurality of angled orifices
49 provided adjacent extrusion aperture 51, annular head
53 threadedly attached to the main body 57 and
surrounding extrusion outlet or orifice 51 and air
chamber 55 which receives the pressurized air from feed
47, and finally solid frame or block 57 in which the
elements described above are formed or provided. Block
57 includes a single molded metallic structure or-
alternatively may include a plurality of different molded
structures as shown in Figure 2, attached to one another
in order to make up the extrusion head illustrated.
In alternative embodiments, one air line may be
provided for opening/closing the needle valves, and a
1~
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separate and independent air line may be provided for
sending pressurized air through orifices 49.
Referring to Figures 2 and 4, the extrusion head 2
of Figure 2 is especially adapted for use as one of the
heads provided in row 7 which extends over and above the
top of the moving batts. Elongated members 59, 61, and
63 are provided along one side of the row 7 of heads 2 in
a manner such that selectively pressurized air conduit 35
within member 59 is in fluid communication with the air
chamber 43 of each extrusion head 2 in row 7 so that when
a predetermined amount of pressure is provided by a
pressurized air source to air conduit 35 of member 59,
the result is that the needle valve 41 of each extrusion
head in row 7 is opened (i.e. the valve biased upward so
as to allow material to be extruded from aperture 51) as
the pressure increases in chamber 43 and becomes greater
than the biasing forced spring 45. Likewise, elongated
member 61 is provided with an elongated heating element
33 therein such that heating element 33 functions to
maintain the heightened temperature of the molten
material flowing within conduit 37 and the air within
conduit 35. Elongated conduit 37 providecl ln member 63
19
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is also in communication with the extrusion feed chamber
39 of each extrusion head 2 in row 7 such that when the
needle valves 41 in row 7 are forced upward due to
pressurized air in 43, this molten material in chambers
37 and 39, which is pressurized, is forced outward
through extrusion aperture 51 resulting in an extruded
synthetic fiber 17 being output from the head.
It is to be pointed out that different types of
extrusion heads may be utilized in different embodiments
of this invention, as the Figure 2 illustration is not
limiting.
Figures 5-7 further illustrate extruded fibers 17
following their discharge from extrusion aperture 51 as
they are blown and/or fall toward the surface (1, 3, 5)
of a batt 18. As shown in Figures 2 and 5, as the fiber
17 is extruded from outlet aperture 51 formed in -
extrusion head 2, it is hit with pressurized air directed
from angularly oriented orifices 49. The pressurized air
streams directed at the fiber 17 forced out of aperture
51 segment or break up the fiber or string of synthetic
material as it comes out of aperture 51, and cause the
resulting segments or fibers to be directed toward the
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surface (1, 3, 5) of batt 18 to be impregnated in an
insipid spin. An insipid spin is created when the air
cuts the fiber starting the fiber to spin, wherein the
spin is maintained in the orbit created by the air
circulation (see Figure 5). In this type of spin, the
spin axis is not at the center lengthwise of the fiber,
and one end of the fiber has a greater spin radius than
the opposite end of the elongated fiber.
As a result of this insipid spin, the fibers 17 upon
reaching the surface of batt 18 are all oriented in
different directions so as to create a crisscross or web
of fibers 17 proximate the surface of the batt, thereby
creating a cross-locking impregnating effect and
resulting in the impregnated batt surface having
substantially equal tensile strength in each of the width
and machine (length) directions. Thus, when the proper
amount of extruded fiber is applied to the batt surface,
it is surprisingly tough to delaminate or dislodge.
Figure 6 illustrates in detail how-a single fiber or
segment 17 directed from an extruded aperture 51 toward
the surface (1, 3, 5) of the batt 18 impregnates the batt
surface (i.e. interlocks upon rnineral fibers 68 of the
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batt). From extrusion aperture 51, individual fibers 17
are directed toward the batt surface as shown in Figure 5
and at 65, the extruded fibers 17 still being very hot
and quasi-molten at this point in time. Upon reaching
the surface of the batt at 67, each fiber, still in a
quasi-molten or flexible state due to its temperature,
falls on and across a plurality of different mineral
fibers of the batt (e.g. glass fibers 68) and sags over
same. As the synthetic extruded fiber 17 cools (i.e.
cures), it shrinks as shown at 69 in a manner such that
the ends 70 of fiber 17 lock onto adjacent batt fibers 68
thereby providing the interloc~ing attachment and
impregnation of the batt surface.
Figure 7 illustrates the surface of a fiberglass
batt 18 following impregnation of a part of the surface
with extruded fibers including EVA. As illustrated,
prior to the deposition and impregnation of fibers 17 on
the surface of the batt, a majority of the glass fibers
68 of the batt 18 are oriented in the machine or length
direction. As a result of the insipid spin created by
orifices 49, fibers 17 when reaching the surface of batt
18 are all oriented in different directions as shown in
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area 71 such that each fiber 17 locks onto glass fiber(s)
68, with the interlocking being provided in a plurality
of different directions so as to, in certain embodiments,
result in improved tensile strength in the width or
cross-machine direction of the batt proximate the surface
thereof.
Figure 4 is a close-up perspective view illustrating
a plurality of extrusion heads 2 that are provlded in row
7 (i.e. Figure 2 embodiment). As illustrated, elongated
members 59, 61, and 63 are provided along the side of
each extrusion head 2 facing batt conveying direction 15.
A separate air supply conduit 81 is provided for each
extrusion head 2 in order to allow pressurized heated air
from chamber 35 to communicate with annular air chamber
55 which supplies pressurized air to orifices 49.
Accordingly, whenever pressurized air is provided through
air supply chamber 35 of member 59, this simultaneously
results in: (i) pressurized air being directed through
each of conduits 81 so as to direct pressurized air
streams out of orifices 49 defined in each extrusion head
2 in row 7; and (ii) pressurized air heing directed via
passageway 83 into the needle valve opening air chamber
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43 of each extrusion head 2 so that pressurized air in 43
forces surface 85 of the needle valve upward against the
biasing force of spring 45 thereby raising and opening
needle valve 41 and allowing the molten material in
chamber 39 to be forced through and out of extrusion
aperture 51. When air is no longer supplied through
conduit or air chamber 35 (i.e. when the selectively
actuated air source is shut off), spring 45 biases needle
valve 41 into its closed position (illustrated in Figure
2) thereby preventing material from being extruded out of
aperture 51. The absence of pressurized air in conduit
35 also stops significant airflow through orifices 49.
As shown in Figure 4, each extrusion head 2 is also
provided with a spring retaining head 87 which functions
to house and support biasing spring 45.
Optionally, spring 45 may be adjustable by adding,
for example, pressure set screw(s) at the top of the head
so as to insure that the spring has a fast enough return,
especially when high pressures are involved.
Figure 3 is a partial perspective view illustrating
how extrusion heads 9 and 11 direct extruded fibers 17
onto the side edge surfaces 3 and 5, respectively, of
24
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batts 18, as alternate batts 18 arc over and are conveyed
beneath member 23 which extends over and above conveyor
belt 13. As illustrated, elongated member 23 includes
air supply conduit 20, and conduit 24 which supplies
pressurized molten material to the extrusion heads 9 and
11. Member 23 and/or conduits 20, 24 are oriented or
aligned substantially parallel to the surface of conveyor
13 (i.e. +20~ from parallel relative to the conveyor
surface). Extrusion heads 9 and 11 are the same as
extrusion head 2 illustrated in Figure 2, except that
members 59, 61, and 63 are provided as part of elongated
member 23 which is disposed in a spaced relation relative
to the extrusion heads. Heads 9 and 11 direct fibers 17
in opposite directions to batt edge surfaces, and are
oriented such that they direct/blow fibers 17
horizontally toward the edge surfaces, as opposed-to
vertically.
Still referring to Figure 3, conduits 91 attached to
air supply member 20 function to supply pressurized air
from member 20 to each of the extrusion heads 9 and 11 so
as to selectively open their needle valves 41 and cause
air to be output from orifices 49. Meanwhile, conduits
CA 02243739 1998-07-21
93 supply heated molten material such as EVA to each
extrusion head from member 24. As illustrated, for each
batt 18 being conveyed along belt 13, first and second
extrusion heads 9 are positioned on one side of the batt
so as to direct extruded fibers 17 onto one edge surface
thereof, while another two extrusion heads 11 are
provided on the other side of the batt in order to direct
extruded fibers 17 onto the opposite edge surface
thereof. In such a manner, each edge surface (3, 5) of
each batt 18 is impregnated with the extruded fibers
directed from the illustrated heads 9, 11.
Still further, in order to carry out this edge
impregnation, every other or alternate batt 18 is
conveyed over top of member 23, such that, for example,
the odd numbered batts 18 are conveyed over member 23
while the even numbered batts 18 are conveyed along belt
13 underneath of member 23 thereby prcviding sufficient
space for extrusion heads 9 and 11 to be mounted to
member 23 via mounting members 95 in order to impregnate
the edge surfaces. As discussed above, in certain
embodiments of this invention, extrusion heads are also
provided adjacent the lower major surface of each batt 18
26
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so as to fully encapsulate the batts with each of the two
major surfaces and each of the two edge surfaces of each
batt with extruded EVA fibers. Also, in certain
embodiments, the top major surface of a batt 18 may be
impregnated with the extruded fibers 17, and the two
opposing edge surfaces may also be impregnated with the
extruded fibers, while the bottom major surface is simply
coated with a layer of vapor impermeable kraft paper.
Kraft paper may in certain embodiments be applied over
top of the extruded fibers on some or all batt surfaces.
Certain flow, temperature, and material parameters
have been found by the instant inventors to be important
in carrying out the different embodiments of this
invention discussed above and are described as follows.
The preferred synthetic material to be extruded into
fibers 17 for lmpregnation of the batt surfaces is ethyl
vinyl acetate (EVA) synthetic resin modified to withstand
high heats so as to ensure no blocking during storage and
shipping. An exemplar EVA is available from H.B. Fuller
Canada, Inc., as material number HM-5782. Other types of
EVA may also be used.
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The viscosity of the EVA during extrusion may range
from about 650 up to about 850 centipoise (cps).
Preferably, the viscosity is from about 650 - 725 cps in
order to get a better flow which results in improved
penetration of the extruded fibers 17 into and around the
fiberglass fibers of the batt 18 prior to curing/cooling.
The lower the viscosity, the higher the heat
required to maintain the EVA in this state. As will be
appreciated by those of skill in the art, a heating
device (not shown) within unit 25 along with heating
elements 33 provided adjacent the extrusion heads 2, 9,
11 maintain the EVA in a molten state as it flows toward
and through the extrusion heads. It has been found that
the best results are obtained when these heating elements
output a temperature of from about 170~ - 270~ C.,
preferably approximately 200~ C. (range of from about 180~
- 225~ C.) or 360~ F., in order to maintain proper EVA
flow through conduits 22, 24, and 37, as well as through
the various extrusion heads discussed above.
Referring to Figures 2 and 5, preferably, from about
four (4) to ten (10) jet orifices 49 are provided
adjacent the output aperture 51 of each extrusion head.
28
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In certain embodiments, six such orifices 49 are provided
and oriented in a circular manner around each output
orifice 51. When the heated air [at from about 200~ -
220~ F.] is initially fed through air conduit 35, in
order to open the needle valves and cause extrusion to
begin, the air pressure within conduit 35 and thus within
chambers 43 and 55 is substantially continuously
increased from about 0 psi up to a level of from about 10
- 75 psi ~preferably from about 10 - 30 psi, and most
preferably about 20 psi). As this air pressure increases
and the pressurized air flows from orifices 49, the
increasing pressure breaks up the fiber being extruded
from orifice 51 into a plurality of individual fibers or
segments 17 as shown in Figure 5. The pressure provided
in air chamber 35 and thus air chamber 55, dictates the
length of fibers 17 which are directed toward the-surface
of the batt to be impregnated. For example, if 15 psi is
provided in chamber 55, the fibers 17 directed toward the
batt will be longer than if 30 psi is provided in chamber
55. For example, when 20 or 30 psi is provided in
chamber 55, each fiber 17 directed toward the batt has a
length of from about one-quarter to three-quarter inches,
29
CA 02243739 1998-07-21
with the fiber length averaging approximately one-half
inch. When about 10 psi is provided to chamber 55, the
individual fibers 17 being directed toward the batt have
an average length of from about three-quarters of an inch
to one and one-half inches. Accordingly, during
extrusion, the pressure of the heated air provided to
chambers 35, 43, and 55 may be at a level from about 10 -
75 psi, preferably from about 10 - 30 psi, and most
preferably about 20 psi.
Also, pump pressure will affect fiber length.
It has been surprisingly found that superior results
are achieved when from about 1.20 to 3.50 gms. per ft2 of
extruded fibers 17 are provided on the surface(s) of a
batt 18 to be impregnated, this amount being most
preferably within a range of from about 1.90 to 2.50 gms.
per ft2. These amounts have been found by the instant
inventors to hold the fibers withln the batt and reduce
dust, while at the same time being aesthetically pleasing
and cost effective. Also, these amounts result in strong
adherence of the fibers 17 to the batt [if too much
extruded fiber is applied, it becomes easily delaminated
and approaches an undesirable vapor barrier].
CA 02243739 1998-07-21
The air provided to chamber 35 is preheated in
certain embodiments of this invention, and may be
preheated at a temperature ranging from about 200~ - 210~
F. in order to achieve optimum results herein.
In row 7 of extrusion heads 2, it has been found
that superior results are achieved when the outlets 51 of
the extrusion heads 2 are spaced from the upper major
surface 1 of batts 18 at a distance of from about 2 to 12
inches, preferably from about 4 to 8 inches. On the
other hand, the results are.best when the extrusion
outlets 51 of heads 9 and 11 are positioned from about 2
- 6 inches from the edge surfaces to be impregnated,
while it is believed that positioning outlets 51 located
adjacent the bottom major surface of the batts 18 to be
impregnated at a distance of from about 1 - 4 inches will
provide the best results.
It has also been found by the insta.nt inventors that
the orientation of orifices 49 is important in achieving
the desired results disclosed herein. Each orifice 49 is
oriented such that its elongated axis which dictates the
air flow toward the extruded fibers is oriented at an
angle of about 20~ relative to a direction which is
CA 02243739 1998-07-21
perpendicular to the axis of needle valve 41. Thus, for
extrusion heads 2 in row 7 that are oriented such that
outlets 51 are directed downward, orifices 49 are
oriented such that their elongated axes which dictate the
air flow direction are angled at from about 10~ - 40~,
preferably about 20~, relati~e to the horizontal.
Each head 2 includes orifice 51 which has a diameter
of approximately 0.020 inches through which the fibers 17
are extruded. The fibers thin out immediately after
leaving apertures 51. When the fibers reach a distance
of approximately 0.070 inches from outlet 51, they have
thinned down to a diameter of from about 0.004 to 0.012
(preferably approximately 0.010) inches, and have started
to coagulate. At this time, the pressurized air streams
lS directed from orifices 49 toward the fibers causes the
fibers to change direction and fall into the inslpid
spin. The insipid spin diameter is controlled by the air
pressure. For exa~ple, at 10 psi, the spin diameter
would be approximately 0.500 inches, and at 60 psi the
diameter would be about 0.750 inches. Once the insipid
spin is created during the initial increase in air
pressure during extrusion start-up, it is maintained as
CA 02243739 1998-07-21
the air pressure increases through the 10 psi level, and
through the 10 - 20 psi level up to the desired level of
approximately 10 to 30 psi.
Still further, the speed of extruding the fiber from
the extrusion heads is controlled by the pressure applied
to conduit 37 giving the system the capability of
maintaining a consistent surface impregnation amount/rate
at different line speeds.
When synthetic material including EVA is used to
form the fibers, the cure or set time of the fibers to
form the impregnation is less than about 5 seconds, and
preferably from about 2-4 seconds.
Additional advantages of the system, resulting from
the impregnation characteristics described above, include
resistance to sagging or packing under vibration which
renders the product suitable for use in vehicles,-
railcars, boats, and the like. Because of the
interlocking impregnation characteristics, this product
may be used in roll-up applications, such as concrete
curing blankets and insulated hanging devices, curtains,
and the like, as well as in cool rooms, such as meat
packaging environments. Still further, after the
CA 02243739 1998-07-21
elongated batts 18 illustrated in Figure 1 are cut into
segments and rolled, they may be forwarded to commercial
or residential insulation sites for use in wall cavities,
attics, and the like. Other applications include sound
insulation inside of duct applications, and the like.
Still another advantage of this invention is that
the synthetic material impregnation represents a
satisfactory vapor permeable layer in the amounts applied
that are disclosed herein. These amounts of EVA, for
example, result in sufficient vapor permeability so that
the compression ratio of the resulting batts 18 is from
about 4 to 10:1, preferably from about 6 to 7:1. For
example, a fiberglass batt roll originally having a seven
(7.0) foot diameter may be compressed down to about a 1.2
foot diameter.
Instead of EVA, other synthetic materials can be
used as the molten material that is extruded via heads 2,
9, and 11 onto batt surfaces in all embodiments herein,
there materials including, for example, hot-melt
polyamides, attactic polyolefines, po].yesters,
polyethylenes, pressure sensitive hot--melts, rubber-based
hot-melts, and moisture cure hot-melts. ~owever, it has
34
CA 02243739 1998-07-21
been found by the instant inventors that none of these
materials are as preferable as EVA types due at least in
part to the short cure times of EVAs. In certain
embodiments, the synthetic may include a combination of
certain of the materials discussed above, or
alternatively be made up of only one or two of these
materials.
It is noted that the EVA inclusive materials are
preferred due to their more rapid cure or set times.
According to alternative embodiments of this
invention, the synthetic material (e.g. EVA) may be
extruded onto at least one surface of a plastic or
polymer (e.g. polyethylene or polypropylene) fiber batt,
instead of mineral fiber batts.
Once given the above disclosure, various other
modifications, features, and improvements will become
apparent to the skilled artisan, such other features,
modifications, and improvements are thus considered a
part of this invention. The scope of which is to be
determined by the following claims.
