U.S. patent application number 11/582285 was filed with the patent office on 2008-04-17 for shingles with low density granules and/or backdust.
Invention is credited to Sanjay Mansukhani, Yishien H. Teng.
Application Number | 20080086970 11/582285 |
Document ID | / |
Family ID | 39301910 |
Filed Date | 2008-04-17 |
United States Patent
Application |
20080086970 |
Kind Code |
A1 |
Teng; Yishien H. ; et
al. |
April 17, 2008 |
Shingles with low density granules and/or backdust
Abstract
A roofing shingle has low density granules adhered to at least a
headlap region on a front surface of the roof shingle.
Inventors: |
Teng; Yishien H.;
(Westerville, OH) ; Mansukhani; Sanjay; (Lewis
Center, OH) |
Correspondence
Address: |
OWENS CORNING
2790 COLUMBUS ROAD
GRANVILLE
OH
43023
US
|
Family ID: |
39301910 |
Appl. No.: |
11/582285 |
Filed: |
October 17, 2006 |
Current U.S.
Class: |
52/518 |
Current CPC
Class: |
Y10T 428/31815 20150401;
Y10T 428/24355 20150115; B32B 37/24 20130101; E04D 2001/005
20130101; E04D 1/26 20130101; Y10T 428/2438 20150115; B05D 7/24
20130101; Y10T 428/25 20150115; B32B 2419/06 20130101; Y10T
428/24372 20150115 |
Class at
Publication: |
52/518 |
International
Class: |
E04D 1/00 20060101
E04D001/00 |
Claims
1. A roofing shingle having a front surface comprising a headlap
region and a prime region, low density granules adhered to at least
the headlap region, wherein the low density granules have a
specific gravity between about 0.7 to about 2.3.
2. The roofing shingle of claim 1, wherein the low density granules
have an apparent density within a range between about 20
lb/ft.sup.3 and about 70 lb/ft.sup.3.
3. The roofing shingle of claim 1, wherein the low density granules
have a specific gravity in a range between about 1.2 and 1.7.
4. The roofing shingle of claim 1, wherein the low density granules
comprise one or more of expanded perlite, expanded shale, expanded
clay, expanded slate, pumice, coal slags, metal slags, agglomerated
flyash, other agglomerates, and combinations thereof.
5. The roofing shingle of claim 1, wherein the low density granules
adhered to the roofing shingle causes a reduction in the wear of a
cutting knife and the force used to cut through the roofing shingle
when compared with the wear of a knife and cutting of a
conventional shingle.
6. The roofing shingle of claim 1, further including low density
particles adhered to at least one of: i) the prime region, ii) a
back surface of the roofing shingle as backdust, and iii) the prime
region and the back surface.
7. The roofing shingle of claim 6, wherein the low density
particles have a specific gravity from about 0.7 to about 2.3.
8. The roofing shingle of claim 6, wherein the low density
particles have a bulk density within a range between about 20
lb/ft.sup.3 and about 70 lb/ft.sup.3.
9. The roofing shingle of claim 1, wherein the prime region
comprises at least one of: i) prime granules having a specific
gravity of at least about 2.5; ii) low density granules having a
specific gravity between about 0.7 to about 2.3; and, iii) a
mixture of prime granules and low density granules.
10. The roofing shingle of claim 1, wherein the shingle further
includes low density granules as filler.
11. The roofing shingle of claim 9, wherein the shingle further
includes low density granules as filler.
12. A method of manufacturing a roofing shingle comprising: coating
a substrate with an organic-based coating material, the coated
substrate having a front surface with a headlap region and a prime
region, and applying low density granules to at least the headlap
region, wherein the low density granules have a specific gravity
between about 0.7 to about 2.3.
13. The method of claim 12, wherein the densities of headlap and
prime granules are different, the method further comprising
calculating the weights of prime and headlap regions separately and
using the prime region weight as a primary parameter for shingle
weight control.
14. The method of claim 12, wherein the low density granules have a
bulk density within a range between about 20 lb/ft.sup.3 and about
70 lb/ft.sup.3 and the prime granules have a bulk density of about
80 lb/ft.sup.3 and above.
15. The method of claim 12, wherein the low density granules have a
specific gravity in a range between about 1.2 and 1.7.
16. The method of claim 12, wherein the low density granules
comprise one or more of expanded perlite, expanded shale, expanded
clay, expanded slate, pumice coal slags, metal slags, agglomerated
flyash, other agglomerates, and combinations thereof.
17. The method of claim 12, wherein the low density granules
applied to the roofing shingle causes a reduction in the wear of a
cutting knife used to cut the roofing shingle when compared with
the wear of a knife used to cut a conventional shingle.
18. The method of claim 12, further including applying low density
particles as at least one of: i) prime granules, ii) backdust on a
back surface of the roofing shingle, and iii) prime granules and
backdust.
19. A method of manufacturing a roofing shingle comprising: a)
applying low density granules as headlap granules on a headlap
region of the roofing shingle, wherein the low density granules
have a specific gravity between about 0.7 to about 2.3; b) applying
one or more of low density granules or prime granules to a prime
region of the roofing shingle, wherein the prime granules have a
specific gravity of at least about 2.5; and c) applying low density
particles as backdust on the roofing shingles
20. The method of claim 19, wherein the densities of the headlap
granules and the prime granules are different, the method further
comprising calculating the weights of the prime and headlap regions
separately and using the prime region weight as a primary parameter
for shingle weight control.
21. The method of claim 19 wherein the low density granules
comprise one or more of expanded perlite, expanded shale, expanded
clay, expanded slate, pumice, coal slags, metal slags, agglomerated
flyash, other agglomerates, and combinations thereof.
22. A roofing shingle having a front surface comprising a headlap
region with headlap material applied thereto, a prime region with
prime material applied thereto, a backdust material and a filler
material, low density granules being applied as one of the headlap
material, prime material, filler material, or backdust materials,
wherein the low density granules have a specific gravity between
about 0.7 to about 2.3.
23. The roofing shingle of claim 23, wherein the low density
granules have an apparent density within a range between about 20
lb/ft.sup.3 and about 70 lb/ft.sup.3.
24. The roofing shingle of claim 23, wherein the low density
granules have a specific gravity in a range between about 1.2 and
1.7.
25. The roofing shingle of claim 23, wherein the low density
granules comprise one or more of expanded perlite, expanded shale,
expanded clay, expanded slate, pumice, coal slags, metal slags,
agglomerated flyash, other agglomerates, and combinations
thereof.
26. The roofing shingle of claim 23, wherein low density granules
are used as headlap material.
Description
TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION
[0001] The present invention relates generally to asphalt-based
roofing materials. The invention also relates to processes for
making the roofing materials.
BACKGROUND OF THE INVENTION
[0002] Asphalt-based roofing materials, such as roofing shingles,
roll roofing and built-up roofing, are installed on the roofs of
buildings to provide protection from the elements. Typically, the
roofing material is constructed of materials including a
reinforcing mat such as a glass fiber mat, an asphalt-based coating
which saturates the mat and coats the front and back, and a layer
of surfacing granules adhering to the top coating as well as a
backdust material to cover the back coating. The asphalt-based
coating usually contains a filler such as pulverized limestone.
[0003] The quantity, composition and properties of the raw
materials used to make a roofing material determine, to a great
extent, the performance of the resultant roofing material (e.g.,
weathering durability, cracking, blistering, algae resistance,
pliability, sticking, and impact resistance). They also determine
the cost to produce the roofing material, and its weight. For a
roofing shingle, the cost to produce the shingle is usually about
60-80% materials cost.
[0004] Traditionally, the roofing material weight has been linked
to its quality and durability, perceived as a primary indicator for
the amount of asphalt used and for the product performance.
However, the product weight can be misleading, since the asphalt
contributes to only a small part of the total weight. For a given
amount of asphalt in a roofing material, its product weight depends
largely on the quantities and densities of other raw materials like
filler, granules, and backdust material used, which fill up the
volume or cover the surface of the roofing material. These raw
materials can be selected from many kinds of mineral or waste
materials in different densities, which meet the requirements for
the manufacture of quality roofing materials. When the raw material
density changes, the roofing material weight will vary, but its
performance may not be necessarily impacted. When purchased by
weight and used for volume filling or surface covering, the
densities of the raw materials can become a leverage for balancing
product weight and cost.
[0005] In the trend of rising energy costs, an unnecessarily
heavier product may result in a higher transportation cost without
benefits to the product performance. Moreover, a heavier roofing
product increases the labor intensity and risk of ergonomic
injuries during handling and application.
[0006] One weight-increasing material that typically does not add
to the useful properties of the installed shingle is the backdust
material. Roofing shingles usually have a backdust material on the
bottom coating to prevent them from sticking together in a bundle
or from sticking together in a roll. The backdust is typically made
from rock, which may be crushed as in talc, carbonate or rock dust.
The backdust may also be produced by screening sediment, such as
silica sand.
[0007] In view of the current roofing materials, there is obviously
a need for roofing materials that are optimized as a whole for
performance, material and transportation costs, and application
convenience. There is also a need for a process for making such
roofing materials.
[0008] The invention will be more readily understood from the
following description of a preferred embodiment thereof given, by
way of example, with reference to the accompanying drawings.
SUMMARY OF THE INVENTION
[0009] A roof covering has a front surface with a headlap region
and a prime region. Low density granules are applied on the headlap
region surface. Colored granules of low density may also be applied
to the prime region surface. In certain embodiments, the low
density granules have a specific gravity between about 0.7 to about
2.3, or an apparent density between about 20 lbs/c.f. and about 70
lbs/c.f. The low density granules are lightweight or porous that
can be natural, processed or recycled materials, such as one or
more of expanded perlite, expanded shale, expanded clay, expanded
slate, pumice, coal slags, metal slags, agglomerated flyash, or
other agglomerates. Similar materials of low density may also be
used as backdust.
[0010] A method of manufacturing a roof covering includes coating a
substrate with an organic-based coating material and applying low
density granules on a headlap region and/or prime region of the
coated substrate, as well as on the backside of the roofing
material. When the densities of headlap and prime granules are
different, an algorithm for sheet weight control will calculate the
weights of prime and headlap regions separately and use the prime
region weight as a primary parameter for product weight
control.
[0011] The foregoing and other objects, features, and advantages of
the invention will appear more fully hereinafter from a
consideration of the detailed description that follows. It is to be
expressly understood, however, that the drawings are for
illustrative purposes and are not to be construed as defining the
limits of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The advantages of this invention will be apparent upon
consideration of the following detailed disclosure of the
invention, especially when taken in conjunction with the
accompanying drawings.
[0013] FIG. 1 is a schematic elevational view of an apparatus for
manufacturing roofing shingles having a low density granule headlap
region.
[0014] FIG. 2 is a perspective view of a bundle of roofing shingles
having a low density granules headlap region and a low density
particle backdust applied to the back surface of the shingles.
DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION
[0015] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which the invention belongs. Although
any methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, the preferred methods and materials are described
herein. All references cited herein, including published or
corresponding U.S. or foreign patent applications, issued U.S. or
foreign patents, or any other references, are each incorporated by
reference in their entireties, including all data, tables, figures,
and text presented in the cited references.
[0016] In the drawings, the thickness of the lines, layers, and
regions may be exaggerated for clarity. It is to be noted that like
numbers found throughout the figures denote like elements. The
terms "top", "bottom", "front", "back", "side", and the like are
used herein for the purpose of explanation only. It will be
understood that when an element such as a layer, region, or panel
is referred to as being "on" another element, it can be directly on
the other element or intervening elements may be present. If an
element or layer is described as being "adjacent to" or "against"
another element or layer, it is to be appreciated that that element
or layer may be directly adjacent to or directly against that other
element or layer, or intervening elements may be present. It will
also be understood that when an element such as a layer or element
is referred to as being "over" another element, it can be directly
over the other element, or intervening elements may be present.
[0017] Referring now to the drawings, there is shown in FIG. 1 an
example of apparatus 10 for manufacturing roofing shingles having
low density headlap granules, and in certain embodiments, low
density granular backdust. Although the description herein will be
illustrated in relation to three-tab roofing shingles (as
illustrated in FIG. 2), it is to be understood that the invention
is also applicable to other types of roof coverings, such as
laminated roofing shingles, roll roofing, or built-up roofing.
[0018] Initially, a substrate is payed out from a roll 12 as a
continuous sheet 14. The substrate can be any type of material
known for use in reinforcing roofing shingles, such as a web, scrim
or felt of fibrous materials such as mineral fibers, cellulose
fibers, rag fibers, mixtures of mineral and synthetic fibers, or
the like. Preferably, the substrate is a nonwoven web of glass
fibers.
[0019] The sheet 14 is passed from the roll through an accumulator
16. The accumulator allows time for splicing one roll of mat to
another, during which time the mat within the accumulator is fed to
the manufacturing process so that the splicing does not interrupt
manufacturing.
[0020] Next, the sheet 14 is passed through a coater 18 where an
organic-based coating material 20 is applied to the sheet 14. The
coating material 20 can be applied in any suitable manner. In the
illustrated embodiment, the sheet 14 is coated with a supply of
hot, molten coating material 20 to completely cover the sheet 14
with the tacky coating material 20. However, in other embodiments,
the coating material 20 can be sprayed on, rolled on, or applied to
the sheet 14 by other means.
[0021] The term "organic-based coating material" means a coating
material containing a substantial quantity of an organic material
such as a bituminous material and/or a polymeric material. Any type
of bituminous material suitable for coating roof coverings can be
used, such as asphalt, tar, pitch, or a mixture thereof. The
asphalt can be either a manufactured asphalt produced by refining
petroleum or by other methods, or a naturally occurring asphalt.
The coating material can also include various additives and/or
modifiers, such as inorganic fillers or mineral stabilizers. In a
typical asphalt roofing shingle, the coating material includes
asphalt and a filler of finely ground inorganic particulate matter,
such as pulverized limestone, in an amount within a range of from
about 40% to about 80% by weight of the coating material.
[0022] In certain embodiments, the filler can comprise low density
granules, as further defined herein.
[0023] The hot coated sheet 14 is passed beneath a series of
granule applicators 22 that discharge protective roofing granules
21, 24 onto the top surface of the sheet 14. One preferred granule
applicator is a granule valve of the type disclosed in U.S. Pat.
No. 6,610,147 to Aschenbeck, which is incorporated herein by
reference in its entirety.
[0024] As schematically illustrated in FIG. 2, the roofing granules
21, 24 comprise at least two types: i) prime roofing granules 21
that are applied to the prime area 23 portion of the shingle that
will be exposed on the roof; and, ii) headlap roofing granules 24,
applied in the headlap area 25, preferably of low density, that are
applied to the portion of the shingle that will be normally
substantially covered on the roof.
[0025] The prime granules 21 generally provide the shingle with its
desired performance characteristics (including aesthetics, coloring
and weathering), while the headlap granules 25 generally keep
adjacent shingles from sticking together and provide similar
performance characteristics where exposed (for example between the
tabs of a strip shingle). Preferred headlap granules 25 are of low
density, which will be described in more detail below. However, the
prime granules 21 may also be made of low density materials that
have a specific gravity less than 2.3 or an apparent density less
than 70 lbs/c.f.
[0026] The granule coated sheet is passed around a drum 26 that
presses the roofing granules 21, 24 into the hot, tacky coating
material and inverts the sheet sufficiently for any non-adhering
roofing granules to fall into a hopper (not shown) for recycling.
While the sheet is inverted, a backdust 28 is applied to the back
surface 54 of the sheet. The backdust 28 is supplied from a
backdust applicator 30. In a preferred embodiment, the backdust 28
can comprise low density granules, as will be described in more
detail below.
[0027] Next, the sheet is passed through a cooling section 32 in
which the coating material is cooled. Any suitable type of cooling
section can be used. In a typical cooling section, the sheet is
passed up and down between a number of rolls and sprayed with water
and/or exposed to cooling air to cool the coating material.
[0028] The sheet is fed through a pattern cutter 34, a preferred
example of which comprises a rotary cutter which includes a cutting
cylinder 36 having a cutting knife 38 or blade. The pattern cutter
cuts the sheet into multiple continuous strips 40 of shingles (one
of which is shown), and cuts a series of cutouts and notches in
each of the strips. Next, each of the strips 40 is fed through a
length cutter 42 which includes a cutting cylinder 44 having a
cutting knife 46. The length cutter cuts the strip into roofing
shingles 48. Finally, the roofing shingles are stacked in a bundle
50 and packaged using suitable equipment (not shown).
[0029] FIG. 2 illustrates a bundle 50 of the roofing shingles 48.
As schematically illustrated in FIG. 2, the roofing granules 21, 24
include the prime granules 23 and the headlap granules 25. The
prime granules 23 are adhered in a prime region on the front
surface 52 of the roofing shingle 48 (the surface exposed when the
shingle is installed on a roof). The prime granules 21 generally
comprise mineral particulate matter that is produced, for example,
from raw mineral ores. The prime granules 21 are generally
characterized by bulk densities in the range of between 80 and 120
lbs/ft.sup.3, unless lightweight prime granules are used.
Furthermore, the specific gravity of the non-lightweight prime
granules 21 is generally at least 2.5, and generally ranges between
2.55 and 3.05, and the hardness of the prime granules generally is
at least about a Moh hardness of 7 or higher.
[0030] Referring again to FIG. 2, the low density headlap granules
24 are adhered in a headlap region 25 on the front surface 52 of
the roofing shingle 48 (the surface that is covered by adjacent
shingles when installed on a roof).
[0031] It has now been found that low density granules 24 can
advantageously be used as a headlap material on roof coverings. In
a preferred embodiment, the low density headlap granules 24 are
suitable for use in a roof covering manufacturing process in direct
substitution for existing headlap materials. This saves the expense
of headlap material without need for modifying the equipment and/or
process to accommodate the new headlap material.
[0032] In certain embodiments, the algorithm for sheet weight
control is modified to recognize the different weights between the
prime and headlap regions. Traditionally, a weight gauge scans
across the sheet of roofing material and collects the weight
information from both prime and headlap regions without
differentiation.
[0033] In one embodiment, the algorithm analyzes the data and gives
instructions for adjusting the gap between two exit rolls of coater
and hence the sheet thickness if necessary. For example, when the
densities of prime and headlap granules are different, the
algorithm collects sheet weight data from the prime and headlap
regions separately. To guarantee the roofing material meets certain
specifications, the weight of the prime region needs to be
maintained at a desired constant specification. Therefore, the
prime region weight may be selected as a primary parameter in the
algorithm for control of roofing material weight, and the headlap
region weight may be controlled in a different manner or ignored
for that purpose.
[0034] The low density headlap granules 24 are generally not
visible when used on the shingle, and therefore the low density
granules may not have to meet any aesthetic or weathering
requirements. The presence of some contaminants in the low density
headlap granules is acceptable, so long as the contaminants are not
harmful to the roof covering manufacturing process or incompatible
with the asphalt, or problematic if exposed between the tabs of the
prime area 23.
[0035] However, for strip shingles that have cut-outs 27 between
tabs 29, the color of the headlap granules 24 of an underlying
shingle is visible through the narrow gaps of an overlying shingle.
If the headlap color is different from a desired color, a preferred
lightweight headlap granules is painted to the desired color, or
colored patterns can be produced with colored granules, which
synchronize with the cut-outs of strip shingles to show the desired
color through the gaps.
[0036] A preferred low density headlap granule 25 can be classified
by size where the low density granules which are large in size
(e.g., retained on a 30 mesh screen [0.59 mm openings]) can be
applied as headlap roofing granules on the roofing shingles.
[0037] The headlap granules typically contribute about 30-40 pounds
of weight for each square of conventional roofing shingles. One
advantage of the low density headlap granules 25 is that the low
density granules add less weight to the shingles, without reducing
the desired properties of the shingle. The reduction in weight also
reduces transportation costs, and benefits the workers who lift and
install shingles on roofs.
[0038] In certain embodiments, the low density granules have
specific gravity of about 2.3 or less, and in certain embodiments,
in a range between about 1.2 and 1.7, and a bulk density within a
range between about 30 lb/ft.sup.3 and about 70 lb/ft.sup.3. By
contrast, conventional prime granules generally have a bulk density
of about 80 lb/ft.sup.3 and above. In certain embodiments, the
granules which are large in size (e.g., retained on a 30 mesh
screen [0.59 mm openings]) are applied as roofing granules on the
roofing shingles. In certain embodiments, the low density headlap
granules 25 can have an average diameter between about 0.1 mm (#120
mesh) and about 2 mm (#7 mesh). Also, in certain embodiments, the
low density headlap granules can have a diameter within a range
between about 0.2 mm (#70 mesh) and about 1.5 mm (#16 mesh).
[0039] In certain embodiments, the low density headlap granules 25
include one or more of expanded perlite, expanded shale, expanded
clay, expanded slate, pumice, glass microspheres, crumb rubber,
polymeric particles or other lightweight low density materials.
Also, in certain embodiments, the low density headlap granules 25
provide higher thermal resistance than conventional headlap
granules.
[0040] The low density headlap granules 25 have good flowability,
such that they are substantially free-flowing when subjected to
pressure or gravity. The good flowability allows the low density
granules to function well as a headlap material, and to be easily
incorporated into a roof covering manufacturing process.
[0041] Another advantage of the low density granules 25 is that the
low density granules have lower abrasive qualities than previously
used types of headlap granules, which may improve the cuttability
of roofing materials, extend the life of knife blades, and reduce
the labor intensity of roofing workers. In certain embodiments, the
lower abrasiveness is due to the relative "softness" (that is, the
lower hardness of such low density materials as perlite and pumice
[Mohs hardness of 5.5] compared to conventional (i.e., high
density) materials such as silica [Mohs hardness of 7]).
Advantageously, the lower abrasive qualities of the low density
headlap granules reduce wear on the cutting knives used to cut the
roofing shingles compared to the amount of wear on the same cutting
knives when the shingles have the same amount of harder granules.
Another advantage is that certain low density granules have a
generally rounded to subangular shape which provides good
handleability, such that the low density granules can be handled
with the bare hands without substantial injury to the hands.
[0042] In another aspect, the low density headlap shingles can
further include low density backdust materials 28 in order to
further decrease the weight of the shingles. In such embodiments,
the low density particles 28 are applied as a backdust on a back
surface 54 of the roofing shingle 48 (the surface facing the roof
when the shingle is installed on the roof). The low density
backdust 28 prevents the roofing shingles 48 from sticking together
in the bundle 50 while reducing the overall weight of the
shingles.
[0043] In such embodiments, the low density backdust materials 28
can have any particle size suitable for use as a backdust material
on a roof covering. Typically, the low density backdust materials
28 can have a particle size similar to fine-grained silica sand. In
certain embodiments, the low density backdust materials 28 can have
an average diameter between about 0.04 mm and about 1.0 mm. In
certain embodiments, the low density backdust materials 28 are
medium in size (e.g., pass through a 30 mesh screen [0.59 mm
openings] but retained on a 325 mesh screen [0.044 mm
openings]).
[0044] As noted above, in certain embodiments, some or all of the
prime granules 21 may be made of similar materials, and coated to
provide the desired coloration and weathering properties. However,
because shingle weight typically takes into consideration the prime
area, it may be less desirable in certain situation to reduce the
weight of the prime granules and thus the prime area of the
shingle. Where this is not a concern, a lightweight shingle may
include one or more of the lightweight headlap, prime and backdust
granules.
[0045] In a further alternative embodiment, the asphalt filler
material is substituted with a lightweight filler material. This
may be done selectively, for example only in the headlap area, or
throughout the shingle coating. Likewise the lightweight filler may
be incorporated only in the back coating, only in the top coating
of the shingle, or both. In yet a further embodiment, a lightweight
filler is pre-applied to the roofing mat prior to coating the mat
with asphalt (filled or unfilled) in the headlap, prime area, or
both. In yet another embodiment, lightweight granules are applied
between the layers of a laminated shingle to increase the thickness
of the shingle without increasing weight. This may be done by
applying the granules between the sheet, on the bottom of the top
layer or the top of the bottom layer. In a preferred embodiment,
large lightweight backdust is applied to the upper sheet.
[0046] The principle and mode of operation of this invention have
been described in its preferred embodiments. However, it should be
noted that this invention may be practiced otherwise than as
specifically illustrated and described without departing from its
scope.
[0047] While the invention has been described with reference to
various and preferred embodiments, it should be understood by those
skilled in the art that various changes may be made and equivalents
may be substituted for elements thereof without departing from the
essential scope of the invention. In addition, many modifications
may be made to adapt a particular situation or material to the
teachings of the invention without departing from the essential
scope thereof. Therefore, it is intended that the invention not be
limited to the particular embodiment disclosed herein contemplated
for carrying out this invention, but that the invention will
include all embodiments falling within the scope of the claims.
* * * * *