U.S. patent application number 12/339493 was filed with the patent office on 2009-04-23 for faced fiberglass board with improved surface toughness.
This patent application is currently assigned to Certain Teed Corporation. Invention is credited to Ronald Moulder, John O. Ruid.
Application Number | 20090100778 12/339493 |
Document ID | / |
Family ID | 34976249 |
Filed Date | 2009-04-23 |
United States Patent
Application |
20090100778 |
Kind Code |
A1 |
Ruid; John O. ; et
al. |
April 23, 2009 |
FACED FIBERGLASS BOARD WITH IMPROVED SURFACE TOUGHNESS
Abstract
An insulation product is provided comprising a sheet of randomly
oriented fibers bonded by a binder. The sheet has first and second
major surfaces and a pair of side portions. A facing layer is
bonded to at least one of the major surfaces. A region of the sheet
proximate to the facing layer is more puncture resistant than a
remainder of the sheet.
Inventors: |
Ruid; John O.;
(Schwenksville, PA) ; Moulder; Ronald; (Lakeland,
FL) |
Correspondence
Address: |
DUANE MORRIS LLP - Philadelphia;IP DEPARTMENT
30 SOUTH 17TH STREET
PHILADELPHIA
PA
19103-4196
US
|
Assignee: |
Certain Teed Corporation
Valley Forge
PA
|
Family ID: |
34976249 |
Appl. No.: |
12/339493 |
Filed: |
December 19, 2008 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10798184 |
Mar 11, 2004 |
7476427 |
|
|
12339493 |
|
|
|
|
Current U.S.
Class: |
52/506.01 |
Current CPC
Class: |
B32B 2307/102 20130101;
B32B 27/12 20130101; B32B 27/04 20130101; B32B 2307/54 20130101;
B32B 2260/048 20130101; D04H 1/72 20130101; D04H 1/54 20130101;
B32B 5/26 20130101; B32B 15/14 20130101; B32B 2262/101 20130101;
B32B 2311/24 20130101; B32B 17/02 20130101; B32B 5/022 20130101;
B32B 2317/122 20130101; B32B 29/02 20130101; E04B 1/90 20130101;
B32B 2307/558 20130101; Y10T 428/237 20150115; E04B 2001/8461
20130101; Y10T 428/238 20150115; B32B 2307/304 20130101; B32B
2410/00 20130101; D04H 1/4218 20130101; Y10T 428/1352 20150115 |
Class at
Publication: |
52/506.01 |
International
Class: |
C04B 14/42 20060101
C04B014/42 |
Claims
1. An insulation product comprising: a sheet of randomly oriented
fibers bonded by a binder, said sheet having first and second major
surfaces and a pair of side portions; and a facing layer bonded to
at least one of said major surfaces, wherein a region of said sheet
proximate to said facing layer is more puncture resistant than a
remainder of said sheet.
2. The insulation product of claim 1, wherein said sheet is a rigid
or semi-rigid insulation board.
3. The insulation product of claim 2, wherein said board is a
fiberglass board having a fiber density greater than about 2.0
pounds per cubic foot.
4. The insulation product of claim 3, wherein said board has a
thickness between about 0.5 to 2 inches.
5. The insulation product of claim 1, wherein said facing layer is
selected from the group consisting of a polymeric, foil, paper, or
FSK or PSK laminate layer.
6. The insulation product of claim 1, wherein said binder is a heat
cured binder, said sheet having a higher percentage by weight of
said heat cured binder in said region compared with a total
percentage by weight of said binder in said sheet, thereby
improving the puncture resistance of said region.
7. The insulation product of claim 1, wherein said sheet includes
at least about 16 percentage by weight binder and said region is
between about 25-33 percent of the thickness of said sheet.
8. The insulation product of claim 7, wherein said sheet includes a
toughness improvement additive in said region.
9. The insulation product of claim 8, wherein said additive
includes a latex additive.
10. The insulation product of claim 8, wherein said additive
improves the toughness of said region by at least 10%.
11. The insulation product of claim 8, wherein said additive
improves the tensile strength of said region.
12. The insulation product of claim 8, wherein said additive
comprises thermoplastic fibers that are meltbonded to said randomly
oriented fibers at least in said region.
13. The insulation product of claim 7, wherein said sheet includes
between about 16-25 percentage by weight binder.
14. The insulation product of claim 1, wherein said region includes
a toughness improvement additive.
15. The insulation product of claim 12, wherein said additive
includes a latex resin.
16. A fiberglass board insulation product, comprising: a rigid or
semi-rigid fiber glass board comprising randomly oriented glass
fibers bonded by a heat cured binder, said board having first and
second major surfaces and a pair of side portions and having a
fiber density greater than about 2.0 pounds per cubic foot; and a
facing layer bonded to at least one of said major surfaces, said
board having a higher percentage by weight of said heat cured
binder in a region of said board proximate to said facing layer
compared with a total percentage by weight of said heat cured
binder in said board, thereby improving a puncture resistance of
said region.
17. The insulation product of claim 16, wherein said board includes
at least about 16 percentage by weight binder and said region is
between about 25-33 percent of the thickness of said board.
18. The insulation product of claim 17, wherein said board includes
between about 16-25 percentage by weight binder.
19. The insulation product of claim 16, wherein said region
includes a toughness improvement additive in said region.
20. The insulation product of claim 19, wherein said additive
includes latex.
21. The insulation product of claim 16, wherein said board has a
thickness between about 0.5 to 2 inches.
22. A fiberglass board insulation product, comprising: a rigid or
semi-rigid fiber glass board comprising randomly oriented glass
fibers bonded by a heat cured binder, said board having first and
second major surfaces and a pair of side portions, said board
having a higher percentage by weight of said heat cured binder in a
region of said board proximate to at least one of said major
surfaces compared with a total percentage by weight of said heat
cured binder in said board, thereby improving a durability of said
region.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional patent application of U.S.
patent application Ser. No. 10/798,184 filed Mar. 11, 2004,
entitled "Faced Fiberglass Board with Improved Surface Toughness,"
now U.S. Pat. No. ______, the entirety of which is hereby
incorporated by reference herein.
FIELD OF INVENTION
[0002] The present invention relates to fiber insulation products,
and more particularly, to fiber insulation board products and
methods of manufacturing the same.
BACKGROUND OF THE INVENTION
[0003] Fiberglass board products are used to impart both thermal
and acoustical insulation to surfaces and enclosures. The bottom
surface of these products is often laminated to or faced with a
facing material, such as plastic, foil, paper or laminates, such as
FSK (foil-scrim-kraft paper) or PSK (plastic-scrim-kraft
paper).
[0004] In some circumstances, it may be desirable to have the
surfaces (faced or unfaced) of the fiberglass board be more rigid
and/or have improved surface toughness. For example, improving the
surface toughness and rigidity of the fiberglass surface proximate
to the facing layer is desired when the facing layer is exposed
after installation in, for example, agricultural buildings such as
open barns where the installed fiberglass board is exposed to
pecking or other damage by birds and other animals. It is also
preferred that the surface toughness and rigidity of the product be
improved without enhancements to the facing layer or layers and
without increasing fiber density, each of which can add significant
expense and/or undesired weight to the product. Fiberglass board
products that address these concerns are not currently known.
[0005] Accordingly, there remains a need for a fiberglass board
product that provides improved surface rigidity and/or toughness
proximate to a facing layer but that can be made without adding
significant additional expense and/or weight to the product.
SUMMARY OF THE INVENTION
[0006] The present invention provides an insulation product
comprising a sheet of randomly oriented fibers bonded by a binder.
The sheet has first and second major surfaces and a pair of side
portions. A facing layer is bonded to at least one of the major
surfaces. A region of the sheet proximate to the facing layer is
more puncture resistant than a remainder of the sheet. The
insulation product provides improved surface rigidity, surface
toughness, puncture resistance, penetration resistance and/or
impact resistance proximate to a facing layer without significant
additional expense and/or without significant additional
weight.
[0007] A method of manufacturing an insulation product is also
provided. A web of randomly oriented fibers generally having a
first major surface and a second major surface and a pair of side
portions is formed on a forming belt. The fibers are coated with a
heat curable binder. The web has a higher percentage by weight of
the heat curable binder in a region of the web proximate to at
least one of the major surfaces compared with a total percentage by
weight of the binder in the web. The web is compressed and heated
to form a sheet of the randomly oriented fibers bonded by the heat
curable binder. The sheet has first and second major surfaces and a
pair of side portions. A facing layer is affixed to the at least
one of the major surfaces of the sheet, wherein a region of the
sheet proximate to the facing layer is more puncture resistant than
a remainder of the sheet.
[0008] In another embodiment, an insulation product is provided
comprising a rigid or semi-rigid fiber glass board having first and
second major surfaces and a pair of side portions. The board
comprises randomly oriented glass fibers bonded by a heat cured
binder. The board has a fiber density greater than about 2.0 pounds
per cubic foot. A facing layer is bonded to at least one of the
major surfaces. The board has a higher percentage by weight of the
heat cured binder in a region of the board proximate to the facing
layer compared with a total percentage by weight of the heat cured
binder in the sheet, thereby improving a puncture resistance of the
region.
[0009] In yet another embodiment, a fiberglass board insulation
product comprises a rigid or semi-rigid fiber glass board
comprising randomly oriented glass fibers bonded by a heat cured
binder. The board has first and second major surfaces and a pair of
side portions. The board has a higher percentage by weight of the
heat cured binder in a region of the board proximate to at least
one of the major surfaces compared with a total percentage by
weight of the heat cured binder in the board, thereby improving a
durability of the region.
[0010] The above and other features of the present invention will
be better understood from the following detailed description of the
preferred embodiments of the invention that is provided in
connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The accompanying drawings illustrate preferred embodiments
of the invention, as well as other information pertinent to the
disclosure, in which:
[0012] FIG. 1 is a side elevational view of an exemplary insulation
product according to the present invention;
[0013] FIG. 2 is a partial side perspective view of a fiberizing
stage used in forming the product of FIG. 1;
[0014] FIG. 3 is a side perspective view of a curing oven stage
used in forming the product of FIG. 1;
[0015] FIG. 4 is a side perspective view of a facing applicator
stage used in forming the product of FIG. 1; and
[0016] FIG. 5 illustrates the steps of an exemplary process of
forming the insulation product of FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0017] Provided herein are methods for manufacturing board
insulation products and the board insulation products made thereby.
Insulation materials generally span the range from light weight,
flexible and resiliently compressible foams and nonwoven fiber webs
to rigid or semi-rigid boards. Generally, these insulating
materials have densities in the range of about 0.5-7 lb/ft.sup.3
(8-112 kg/m.sup.3). Foam and nonwoven fiber web materials are
usually provided in continuous sheeting that is sometimes cut to
preselected lengths, thus forming batts. These articles are usually
characterized as "low density," having a density in the range of
about 0.5-6 lb/ft.sup.3 (8-96 kg/m.sup.3), and preferably about 1-4
lb/ft.sup.3 (16-64 kg/m.sup.3), and more preferably 0.3 to 1.5
lb/ft.sup.3 (4.8-24 kg/m.sup.3). The thickness of the insulation
blanket or mat is generally proportional to the insulated
effectiveness or "R-value" of the insulation. These low density
insulation mats typically have a thickness between about 3.5-10
inches.
[0018] In contrast, rigid to semi-rigid insulation boards ("high
density" insulation) tend to have densities in the higher portion
of the range, at about 2-7 lb/ft.sup.3 (32-112 kg/m.sup.3), and
preferably at about 4-7 lb/ft.sup.3 (64-112 kg/m.sup.3). These
boards customarily are produced as sheets typically having a
thickness in the range of about 0.25-2 inches, and more preferably
about 0.5-2 inches, and about 2-4 feet wide by about 4-12 feet in
length. The board insulation products of this invention are well
suited to agricultural buildings where fowl fly into or peck at the
wall surfaces. They may are also suitable as sheathing, building
insulation, duct liner and automotive insulation.
[0019] With reference to the Figures, and more particularly to FIG.
1 thereof, insulation product 100 is illustrated. Insulation
product 100 preferably includes a high density board insulation
sheet 10 (as described above) formed from organic fibers such as
polymeric fibers or inorganic fibers such as rotary glass fibers,
textile glass fibers, stonewool (also known as rockwool) or a
combination thereof. Mineral fibers, such as glass, are preferred.
Sheet 10 has a first and second major surfaces 11, 12,
respectively, and first and second side portions 13 and 14,
respectively. In some embodiments, a facing layer 16, which may be
a polymeric, foil (e.g., aluminum), paper, or FSK or PSK laminate
layer, is attached to the second major surface 12 of the sheet 10.
This material tends to improve the strength of the duct board
material, as well as improve abrasion resistance, toughness,
cleanability and appearance of the board. The facing layer 16 may
be affixed to the surface 12 by an adhesive, such as a hot-melt or
water-based adhesive, and may or may not be a vapor retardant to
reduce water vapor permeability. The facing layer 16 can be vapor
impermeable or permeable, depending on its makeup, degree of
perforation, and intended use. The product 100 may optionally
include a second facing layer 18 affixed to the first major surface
11.
[0020] In an exemplary embodiment, the sheet 10 is formed from
glass fibers bound together with a heat cured binder, such as a
resinous phenolic material like phenolformaldehyde resins or phenol
urea formaldehyde (PUFA). Melamine formaldehyde, acrylic,
polyester, urethane and furan binder may also be utilized in some
embodiments. Conventional insulation board sheets typically have
about 15% or less of their dry weight attributable to the heat
cured binder.
[0021] In an exemplary embodiment of sheet 10, the region of sheet
10 proximate to at least one major surface, such as second major
surface 12 and facing layer 16, preferably the region within about
1/3 of the thickness "T" of the sheet 10, and more preferably the
region within about 1/4 of the thickness T of the sheet 10, has a
higher dry weight percentage of heat cured binder than the sheet 10
as a whole. It is believed that locally increasing binder content
proximate to the second major surface 12 and facing layer 16
increases the overall durability and wear resistance of the
product, such as by improving the product's resistance to tearing
by improving, for example, the rigidity, surface toughness, tensile
strength, puncture resistance, penetration resistance and/or impact
resistance (hereinafter, referred to as "durability") of that
region after the binder cures, and particularly increases the
durability of second major surface 12, to which facing layer 16 is
bonded. Cured binder, however, can become very brittle. Therefore,
too much binder agent can have an adverse effect on the durability
of the region, making the second major surface 12 brittle. In one
embodiment, the dry weight percentage of binder in the sheet 10 is
increased between about 1-10% (such that the total percentage is
between about 16-25%, but possibly higher) in order to provide the
increased binder in the region proximate to the surface 12. As
noted, the excess binder (compared to conventional board insulation
products) is concentrated in the region proximate to a major
surface, i.e., in the region in which it is desired to increase
durability. In one embodiment, the insulation product including the
localized increased binder content provides for improved puncture
resistance in the insulation board as measured by the Beach
puncture test, referred in TAPPI and ASTM as test method T 803,
which is designed to measure resistance to a pyramidal point
penetrating through a sheet material such as corrugated board or
FSK. UL test 181 (Standard for Factory-Made Air Ducts and
Connections), UL section 13, 9.sup.th Edition (Sep. 19, 2002),
which notes resistance to a circular face penetrating through a
section of duct board, may also be used. In one embodiment, the
puncture resistance of the insulation product is improved at least
10% over the standard board product.
[0022] In an exemplary embodiment, a non-brittle toughening agent
is applied along with the binder agent to the fibers in the sheet
10 in order to maintain the amount of the binder within the region
at a level that keeps the region from becoming too brittle. In one
embodiment, the toughness improvement additive is a "crack stop"
material such as latex, often added to materials such as
impact-hardened polystyrene to reduce brittleness. The toughening
agent preferably provides greater tear resistance, puncture
resistance, wear resistance, tensile strength, toughness,
durability, resiliency, penetration, impact strength or a
combination thereof. In one embodiment, the additive improves the
toughness of said region by at least 10%.
[0023] As noted above, in one embodiment, the sheet 10 optionally
includes a second facing layer 18 coupled to the first major
surface 11 of sheet 10. In an exemplary embodiment, facing layer 18
which may be a polymeric, foil (e.g., aluminum), paper, or FSK or
PSK laminate layer like facing 16 of the sheet 10. Alternatively,
facing layer 18 may include a non-woven facing layer that protects
at least the first major surface 11 of the insulation blanket or
mat 10 as taught by, for example, commonly assigned U.S. patent
application Ser. No. [Attorney Docket No. D0932-00399], entitled
"Insulation Product Having Nonwoven Facing and Process for Making
Same," to Michael J. Lembo and Murray S. Toas or commonly assigned
related application Nos. [Attorney Docket No. D0932-00400],
entitled "Insulation Product Having Nonwoven Facing Layer," and
[Attorney Docket No. D0932-00400], entitled "Method of Making
Insulation Product Having Nonwoven Facing," to David I. Suda et al.
filed Jan. 8, 2004. The nonwoven layer can also coat one or both
side surfaces 13 and 14, and even part or all of the second major
surface 12, to reduce the release of unbound fibers and dust. In
further embodiments, the nonwoven layer 18 can be applied to the
cut end surfaces, after the chopper 112 step (FIG. 4). In one
embodiment, binder content may also be increased proximate to the
surface 11 to impart additional surface toughness thereto.
[0024] A process for forming the insulation product 100 of FIG. 1
is described below in connection with FIGS. 2-5.
[0025] FIG. 2 shows a partial perspective view of a fiberizing
stage 200 for forming an uncured fiber web. Stacked fiber layers
are formed in stage 200 by melt spinning molten material, such as
glass, into veils 20 of fine fibers using a plurality of fiberizing
units 22a-22f. In an exemplary embodiment, three, four or even more
fiberizing units 22 are utilized. The veils of fibers enter a
forming hood 24 where a binder, such as a phenolic resin described
above, in an aqueous carrier (or water and binder in sequence) is
sprayed onto the veils 20. In the forming hood 24, fibers are
accumulated and collected as a web on a chain, belt or other driven
conveyor 26. The fibers accumulate on the conveyor 26, gradually
increasing the thickness of the mat.
[0026] In one embodiment, the group of fibers that will later form
the region proximate to second major surface 12 of sheet 10 are
sprayed with extra binder relative to the rest of the fibers in the
web to provide the enhanced surface toughness discussed above for
product 100 once cured. For example, the fibers from the first
and/or second fiberizers 22a, 22b may be sprayed with additional
binder agent. As noted above, a toughening agent can also be added
to the fibers that eventually form the region proximate to second
major surface 12. Toughening agents may include a solvent based or
latex additive, such PVA (polyvinyl acetate), PVOH (polyvinyl
alcohol), PVC (polyvinyl chloride), SBR (styrene-butadiene rubber),
acrylic, or thermoplastic additives, such as polyester, polyolefin
or nylon fibers, which are melted at curing oven temperatures to
form a melt bond with the randomly oriented fibers of the board to
increase mechanical properties thereof. The toughening agent can be
blended with the binder and sprayed along with the binder onto the
fibers.
[0027] After the web exits the fiberizing stage 200, it is conveyed
to the curing stage 300 of FIG. 3. for compressing and curing the
web to a desired thickness and density. While in the oven, the web
is heated in order to cure the binder and adhere the portions to
one another so as to form the homogeneous mass of sheet 10.
[0028] FIG. 3 shows an apparatus 300 for packing the loose fiber
glass material 20 into a fiber board layer 10. Stage 300 is
described in detail in commonly assigned U.S. application Ser. No.
10/141,595 to John O. Ruid, et al., entitled "Duct Board Having Two
Facings", the entirety of which is hereby incorporated by reference
herein. The fibers are loaded onto a conveyor 120 and delivered to
the curing oven 115. Curing oven 115 typically heats the uncured
web at a temperature between about 300-600.degree. F., and
preferably between about 400-560.degree. F., and more preferably
between about 450-525.degree. F., for a period typically between
about 199 to 20 seconds (30-300 feet per minute (fpm)), and
preferably between about 150-24 seconds (40-250 fpm), and more
preferably between about 120-30 seconds (50-200 fpm) for a 100 foot
long oven while the uncured web is held and conveyed by a series of
compression conveyors flights 111 and 112 within the curing oven.
The fiber board layer 10 is formed by compressing the web of resin
coated glass fibers 20 from an initial thickness of about 25
centimeters to an appropriate thickness (e.g., 0.5-2'') and density
(preferably at about 4-7 lb/ft.sup.3 (64-112 kg/m.sup.3) and curing
the resin binder. Typically, the curing step includes blowing hot
air through the web 20.
[0029] Web 20 is shown generally having a first major surface 21, a
second major surface 23 proximate to conveyor 120 and a pair of
side surfaces (one of which is not shown). In one embodiment, the
region of the web proximate to second major surface 23 has a higher
percentage by weight of the heat curable binder compared with a
total percentage by weight of the binder in the web. This region
also optionally includes toughening additives, such as a latex
resin, described above.
[0030] Assuming that the fibers emerge from the rotary spinning
apparatus of FIG. 2 at a relatively constant mass flow rate, the
mass per unit area is controlled by the line speed of oven flights
111 and 112, and the density is a function of the line speed and
the spacing between flights 111 and 112 (i.e., the board
thickness). For a constant board thickness, the conveyor speed of
flights 111 and 112 determines density. Therefore, less dense duct
board materials are produced at a higher speed.
[0031] In one embodiment, second facing layer 18 is a non-woven
layer applied to the top surface of the loose fiber glass 20 before
the loose fiber glass 20 enters the oven 115. Adhesive 50 is
applied to the layer 18 at a rate sufficient to penetrate the layer
18. The penetrated adhesive 50 "tacks" the layer 18 to the top oven
flight 111. The bottom side of the fiber board layer 10 (bottom in
FIG. 3) is made smooth, so that the exterior facing (e.g., FSK) 16
can be applied and readily adhered. The smooth surface of exterior
side (i.e., second major surface 12) is formed by running top
flight 111 and bottom flight 112 at different speeds. The exterior
surface (the side to be made smooth) is "skidded" in the curing
oven 115. That is, the surface 12 moves relative to the bottom
flight 112. When the sheet 10 and layer 18 emerge from the curing
oven 115, the top flight 111 peels away from the top of the layer
18. The sheet 10 with optional facing layer 18 is then provided to
the facing applicator stage 400 of FIG. 4. In an alternative
embodiment, layer 18 is applied after curing oven stage 300.
[0032] With respect to FIG. 4, a continuous glass fiber sheet 10
formed in accordance with the process of FIGS. 2-3 is presented by
a feed conveyer 104 to a heated roll 102, to which is
simultaneously supplied a continuous web of facing layer 16, fed
between the heated roll 102 and the cured glass fiber sheet 10. The
web of facing layer 16 is fed via roller 102 of FIG. 4 after being
coated with an adhesive from adhesive applicator 109 to the second
major surface 12 of board 10. Facing layer 16 is fed from a roll
108 on payout stand 118 and through an accumulator 138 for
tensioning facing layer 16. In addition, the outside surface of the
web can be marked at a marking station 114 with identifying
information such as the R-value of the insulation board 10 and the
production lot code before the layer 16 is applied to the bottom of
the glass fiber board 10. The faced glass fiber sheet is
transported away from the heated roll 102 by a tractor section 106,
and delivered to a chopper 112, which periodically chops the sheet
to form insulation products 100. The sheet may also be provided to
a slicer 125 to slice the sheet into sections having desired
widths. The insulation products 100 so formed are then transported
to packaging equipment (not shown).
[0033] FIG. 5 is a flow chart diagram of an exemplary process for
forming the insulation product 100. At step 500, an uncured fiber
web 20 is formed on conveyor 26. Fibers in at least a region
proximate to where a facing layer 16 is to be applied are provided
with additional binder agent relative to the overall binder content
of the web. At step 502, the uncured web 20 is provided to a curing
oven 115 for compression and curing of the web to form rigid board
sheet 10. Optionally, a top nonwoven facing layer 18 is applied and
adhered to the board 10. A region of the sheet having the increased
levels of binder agent, and optionally the toughening additives, is
more resistant to tearing than the remainder of the sheet. At step
504, an exterior facing 16 (e.g., FSK) is adhered to the smooth
second major surface 12 of the sheet 10. At step 506, sheet 10 is
optionally sliced and cut to form final insulation product 100. The
method provides an insulation product with improved surface
rigidity and/or toughness proximate to a facing layer without
adding significant additional expense and/or weight to the
product.
[0034] Although various embodiments have been illustrated, this is
for the purpose of describing and not limiting the invention.
Various modifications, which will become apparent to one of skill
in the art, are within the scope of this invention described in the
attached claims.
* * * * *