U.S. patent application number 14/712747 was filed with the patent office on 2015-09-03 for method for making a fibruous absorbent material.
The applicant listed for this patent is MCNEIL-PPC, INC.. Invention is credited to Paul Y. Fung.
Application Number | 20150247271 14/712747 |
Document ID | / |
Family ID | 47879230 |
Filed Date | 2015-09-03 |
United States Patent
Application |
20150247271 |
Kind Code |
A1 |
Fung; Paul Y. |
September 3, 2015 |
METHOD FOR MAKING A FIBRUOUS ABSORBENT MATERIAL
Abstract
An absorbent material including a fibrous material having a
plurality of individual fibers forming a fiber matrix, a plurality
of absorbent fibers, wherein the plurality of absorbent fibers are
impregnated within the fiber matrix by means of a needlepunch
process.
Inventors: |
Fung; Paul Y.; (New York,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MCNEIL-PPC, INC. |
Skillman |
NJ |
US |
|
|
Family ID: |
47879230 |
Appl. No.: |
14/712747 |
Filed: |
May 14, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14187797 |
Feb 24, 2014 |
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14712747 |
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13236788 |
Sep 20, 2011 |
8695185 |
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14187797 |
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Current U.S.
Class: |
28/108 ;
28/115 |
Current CPC
Class: |
D04H 1/498 20130101;
D10B 2509/026 20130101; D04H 1/64 20130101; D04H 1/4266 20130101;
D04H 1/46 20130101; D10B 2401/022 20130101; A61F 13/15642 20130101;
D04H 1/58 20130101; D04H 1/488 20130101; D04H 1/4382 20130101; D04H
18/02 20130101 |
International
Class: |
D04H 1/488 20060101
D04H001/488; D04H 1/498 20060101 D04H001/498; D04H 18/02 20060101
D04H018/02; A61F 13/15 20060101 A61F013/15 |
Claims
1. A method for making an absorbent material comprising the steps
of: providing a fibrous material including a plurality of
individual fibers forming a fiber matrix; depositing a plurality of
absorbent fibers on a top surface of the fibrous material; and
impregnating the plurality of absorbent fibers into the fiber
matrix by means of a needlepunch process.
2. The method according to claim 1, wherein each of the plurality
of individual fibers has fiber diameter within the range of between
about 11 .mu.m and 100 .mu.m.
3. The method according to claim 2, wherein each of the plurality
of absorbent fibers has fiber diameter with the range of between
about 10 .mu.m and 40 .mu.m.
4. The method according to claim 3, wherein each of the plurality
of individual fibers has a fiber diameter that is at least 1 .mu.m
greater than a fiber diameter of each of the absorbent fibers.
5. The method according to claim 1, wherein the fibrous material
has a thickness prior to the plurality of absorbent fibers being
impregnated within the fibrous material and wherein the absorbent
material has a thickness after the absorbent fibers have been
impregnated within the fibrous material.
6. The method according to claim 5, wherein a percent change
between the thickness of the fibrous material prior to the
plurality of absorbent fibers being impregnated therein and a
thickness of the absorbent material after the absorbent fibers have
been impregnated within the fibrous material is less than 50%.
7. The method according to claim 6, wherein the percent change is
less than 30%.
8. The method according to claim 7, wherein the percent change is
less than 15%.
9. The method according to claim 1, wherein the fibrous material is
a fibrous non-woven material.
10. The method according to claim 9, wherein the fibrous non-woven
material is formed from a plurality of fibers selected from the
group consisting of polyester, nylon, co-polyester, polyethylene,
polypropylene, polylactic acid and combinations thereof.
11. The method according to claim 10, wherein the fibrous non-woven
is made by one of an airlaid process, a card and bind process or a
resin and adhesive bond process.
12. The method according to claim 11, wherein the plurality of
absorbent fibers are selected from the group consisting of hard
wood pulp, soft wood pulp, rayon, cotton, and combinations
thereof.
13. The method according to method according to claim 4, wherein
the needlepunch process is carried out by means a plurality of
individual pins adapted to impregnate the absorbent fibers within
the fiber matrix.
14. (canceled)
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application is a continuation application of
U.S. patent application Ser. No. 13/236,788 filed Sep. 20, 2011,
the entirety of which application is hereby incorporated by
reference herein as if fully set forth herein.
FIELD OF THE INVENTION
[0002] The present invention generally relates to an absorbent
material and a method for making the same. More particularly, the
present invention relates to an absorbent material for use in
disposable sanitary absorbent products such as sanitary napkins,
pantiliners, tampons, diapers, adult incontinence products, and the
like.
BACKGROUND OF THE INVENTION
[0003] Lofty, resilient, non-woven webs, that is nonwoven webs that
have a high degree of loft and the tendency to retain such loft,
are well known. In addition, it is well known that such lofty,
resilient, non-woven webs may be used in disposable sanitary
products such as sanitary napkins, pantiliners, tampons, diapers,
adult incontinence products, and the like. A perceived benefit of
such lofty, resilient, non-woven webs is that such materials may
deliver enhanced comfort to a user of such disposable sanitary
products since the lofty, resilient, nonwoven webs may tend to
conform to, and move with, the user's body during use.
[0004] A problem with lofty, resilient, nonwoven webs is that due
to the loft of such materials (i.e. their low density) such webs
are not particularly absorbent. In addition, such materials may
exhibit poor rewet properties. That is, such materials may release
or "wet back" fluid when subjected to an external pressure.
[0005] In view of the foregoing there is a need for a lofty,
resilient, non-woven web that also provides superior fluid handling
characteristics.
SUMMARY OF THE INVENTION
[0006] In view of the foregoing, the present invention provides, a
method for making an absorbent material including the steps of
providing a fibrous material including a plurality of individual
fibers forming a fiber matrix, depositing a plurality of absorbent
fibers on a top surface of the fibrous material, and impregnating
the plurality of absorbent fibers into the fiber matrix by means of
a needlepunch process.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Examples of embodiments of the present invention will now be
described with reference to the drawings, in which:
[0008] FIG. 1 is a sectional schematic view of an absorbent
material according to a first embodiment of the present
invention;
[0009] FIG. 2 is a schematic view of an apparatus for making the
absorbent material shown in FIG. 1;
[0010] FIG. 3 is a schematic view of the encircled portion of the
apparatus shown in FIG. 2 depicting a needle employed in the
apparatus, a top surface of a substrate, and absorbent fibers
arranged on the top surface of the substrate;
[0011] FIG. 3a is a detailed view of the encircled portion of the
needle shown in FIG. 3;
[0012] FIG. 3b-3e depict the manner in which the needle impregnates
the absorbent fiber within the substrate;
[0013] FIG. 4 is a sectional schematic view of an absorbent
material according to a second embodiment of the present
invention;
[0014] FIG. 5 is a sectional schematic view of an absorbent
material according to a third embodiment of the present invention;
and
[0015] FIG. 6 is a schematic view of an apparatus for making the
absorbent material shown in FIG. 5.
DETAILED DESCRIPTION OF THE INVENTION
[0016] Throughout the present specification, the same or similar
reference numbers have been used to identify the same or similar
elements of the various embodiments of the present invention
described herein.
[0017] Reference is made to FIG. 1 which illustrates a sectional
schematic view of an absorbent material 10 according to a first
embodiment of the present invention. As shown in FIG. 1, the
absorbent material 10 is formed from a fibrous material 12
including a plurality of individual fibers 14 that form a fiber
matrix 16. The absorbent material 10 further includes a plurality
of absorbent fibers 18. As shown, the absorbent fibers 18 are
impregnated within the fiber matrix 16.
[0018] The fibrous material 12 is preferably a fibrous nonwoven
material made by a known nonwoven manufacturing technique such as
an airlaid process, a card and bind process or a resin and adhesive
bond process. Preferably the nonwoven material is a "high loft"
nonwoven. Specifically, the nonwoven preferably has a density lower
than 0.05 g/cc, and preferably between about 0.01 g/cc and 0.03
g/cc, prior to the impregnation of the nonwoven with the absorbent
fibers 18. The individual fibers 14 forming the fibrous nonwoven
material may be selected from fibers including synthetic,
nonabsorbent fibers that may or may not be wettable, for example
hydrophilic fibers, hydrophobic fibers, and combinations thereof.
Specific fiber types include, but are not limited to, polyester,
nylon, co-polyester, polyethylene, polypropylene, and polylactic
acid. Of course the fibrous nonwoven material may be formed from a
single nonabsorbent fiber type listed above or alternatively may be
formed from a mixture of the fiber types listed above. The surface
of nonabsorbent fibers 14 forming the fibrous material 12 may be
rendered wettable by treating such fibers with a suitable surface
treatment, such a surfactant or like.
[0019] Each of the fibers 14 forming the fibrous nonwoven material
preferably has a fiber diameter within the range of 11 .mu.m and
100 .mu.m. The fibrous material 12 preferably further includes a
binder material, such as a latex binder. The binder material is
preferably present in the fibrous material 12 in an amount between
about 30% by weight to about 50% by weight.
[0020] The absorbent fibers 18 are preferably selected from
cellulosic fiber types, such as, but not limited to, hard wood
pulp, soft wood pulp, rayon, and cotton. The absorbent material 10
may include a single absorbent fiber type of those listed above or
in the alternative may include multiple fiber types of those listed
above (i.e. a mixture of absorbent fibers). Each of the absorbent
fibers 18 preferably has fiber diameter within the range of 10
.mu.m and 40 .mu.m.
[0021] The individual fibers 14 forming the fibrous material 12 and
the absorbent fibers 18 are selected such that each of the
individual fibers 14 has a fiber diameter that is at least 1 .mu.m
greater than a fiber diameter of each of the absorbent fibers
18.
[0022] As will be discussed in greater detail below, the absorbent
fibers 18 are impregnated within the fiber matrix 16 by means of a
needlepunch process according to the present invention. The
needlepunch process according to the present invention, described
in detail below, allows the absorbent fibers 18 to be impregnated
within the fiber matrix 16 without the fibrous material 12 losing
its high loft properties. Specifically, the density of fibrous
material 12 prior to being impregnated with the absorbent fibers 18
is preferably within the range of 0.01 g/cc and 0.03 g/cc.
[0023] The fibrous material 12 preferably has a thickness in the
range of about 1.5 mm to about 5 mm prior to impregnation of the
fibrous material 12 with the absorbent fibers 18. After
impregnation of the fibrous material 12 with the absorbent fibers
18 the absorbent material 10 retains substantially the same
thickness as the original fibrous material. Specifically, a percent
change between the thickness of the fibrous material 12 prior to
the plurality of absorbent fibers 18 being impregnated therein and
a thickness of the absorbent material 10 after the absorbent fibers
18 have been impregnated within the fibrous material 12 is
preferably less than 50%, more preferably less than 30% and most
preferably less than 15%. This relatively small change in thickness
reflects that the absorbent material 10 retains the high loft
properties of the fibrous material 12 while at the same time
delivers superior fluid handling capabilities. The percent change
in thickness is calculated as follows:
% .DELTA.T=(Ti-Tf)/Ti; where [0024] Ti=Initial Thickness of Fibrous
Material 12 [0025] Tf=Final Thickness of Absorbent Material 10
[0026] A method of making the absorbent material 10 will now be
described with reference to FIG. 2 which depicts a schematic
representation of an apparatus 19 for making the absorbent material
10. As shown in FIG. 2, a web of fibrous material 12 is fed from a
supply roll 20 and conveyed in a machine direction by a plurality
of rolls 22, 24 and 26. A gravity fed hopper 28, or the like, is
utilized to apply a selected amount of absorbent fibers 18 to a top
surface 30 of the fibrous material 12. Thereafter, the fibrous
material 12 is further conveyed in a machine direction and passed
through a conventional needlepunch apparatus 32 of the type known
to those of skill in the art. In the method according to the
present invention, the needlepunch apparatus 32 functions to
impregnate the absorbent fibers 18 within the fibrous material 12
by means of a plurality of needles 34.
[0027] As is known to those of skill in the art, a conventional
needlepunch apparatus includes a plurality of needles that are
normally adapted to mechanically orient and interlock the fibers of
a spunbonded or carded web. In the method according to the present
invention, the needles 34 of the needlepunch apparatus 32 are used
to impregnate absorbent fibers 18 within the fibrous material 12. A
needle 34 suitable for use in the method according to the present
invention is depicted in FIG. 3 and FIG. 3a. As shown in FIG. 3a,
the needle 34 generally includes a blade 36, a barb 38, and a
throat section 40. The total barb depth of the barb 38 is indicated
by letter "d" in the FIG. 3a.
[0028] For purposes of the present invention, it is critical that
the barb depth "d" is selected such that a radius of each of the
absorbent fibers 18 is smaller than the barb depth "d". The radius
of each absorbent fiber 18 is at least 0.5 .mu.m smaller, for
example 1 .mu.m smaller than the barb depth. In addition the barb
depth "d" should be selected such that each of the individual
fibers 14 of the fibrous material 12 has a radius that is larger
than the barb depth "d". The radius of each individual fiber 14 of
the fibrous material 12 is at least 0.5 .mu.m larger, for example 1
.mu.m larger than the barb depth. If you have a multiple denier
fibrous material 12, the diameter of the smallest diameter fiber 14
must be larger than the diameter of each of the absorbent fibers
18.
[0029] By selecting barb depth "d" as described above, the
plurality of needles 34 in the needlepunch apparatus effectively
grasp the absorbent fibers 18 and thus can impregnate such
absorbent fibers 18 within the fibrous material 12, as shown in
FIGS. 3b-3e. On the other hand, the plurality of needles 34 will
not grasp the individual fibers 14 of the fibrous material 12 and
thus will not destroy the "high loft" properties of the fibrous
material 12. In this manner the final absorbent material 10 is
provided with superior fluid handling properties while still
retaining the high loft properties of the fibrous material 12.
Needles particularly useful in the present method are commercially
available from the Foster Needle Co., Inc., Manatowoc, Wis., under
product designation "The Foster Formed Barb".
[0030] Referring again to FIG. 2, after the fibrous 12 has been
impregnated with the absorbent fibers 18 the resultant absorbent
material 10 is further conveyed in a machine directly by rolls 28
and 30. At this point in the process the absorbent material 10 may
be arranged in a rolled form for storage or may be further conveyed
for incorporation into disposable sanitary absorbent products such
as a sanitary napkin, pantiliner, tampons, diaper, adult
incontinence product, or the like.
[0031] Alternatively, as shown in FIG. 2, the fibrous material 12
may be further conveyed to a superabsorbent application station 42.
The superabsorbent application station 42 comprises a gravity fed
hopper 44 structured and arranged to apply a selected amount of
superabsorbent polymer material 46 to a top surface 30 of the
fibrous material 12. Of course, any suitable means known to those
of skill in the art, such as a pressure fed nozzle or the like, may
be used to apply the superabsorbent polymer material 46 to the top
surface 30 of the fibrous material 12. After the superabsorbent
polymer material 46 is applied to the top surface 30 of the fibrous
material 12, the fibrous material 12 is conveyed over a vacuum 50
that functions to draw the superabsorbent polymer material 46 into
the fiber matrix 16 of the fibrous material 12. The resultant
absorbent material 10a, an absorbent material according to a second
embodiment of the invention, is shown in FIG. 4. As shown, the
superabsorbent polymer 46 has been drawn into the fiber matrix 16
of the fibrous material 12 and functions to further enhance the
fluid handling capabilities of the absorbent material 10a.
[0032] For the purposes of the present invention, the term
"superabsorbent polymer" (or "SAP") refers to materials which are
capable of absorbing and retaining at least about 10 times their
weight in body fluids under a 0.5 psi pressure. The superabsorbent
polymer particles of the invention may be inorganic or organic
crosslinked hydrophilic polymers, such as polyvinyl alcohols,
polyethylene oxides, crosslinked starches, guar gum, xanthan gum,
and the like. The particles may be in the form of a powder, grains,
granules, or fibers. Preferred superabsorbent polymer particles for
use in the present invention are crosslinked polyacrylates, such as
the product offered by Sumitomo Seika Chemicals Co., Ltd. of Osaka,
Japan, under the designation of SA70.
[0033] Referring again to FIG. 2, after the absorbent material 10a
is conveyed past the vacuum 50 the absorbent material 10a may be
further conveyed in a machine direction by roll 51 and arranged in
a rolled form for storage or may be further conveyed for
incorporation into a disposable sanitary absorbent products such as
a sanitary napkin, pantiliner, tampons, diaper, adult incontinence
product, or the like.
[0034] Reference is made to FIG. 5 which illustrates a sectional
schematic view of an absorbent material 10b according to a third
embodiment of present invention. As shown, the absorbent material
10b is formed from a fibrous material 12 including a plurality of
individual fibers 14 that form a fiber matrix 16. The absorbent
material 10b further includes a first plurality of absorbent fibers
18a arranged in a first layer 52 and a second plurality of
absorbent fibers 18b arranged in a second layer 54. The absorbent
fibers 18a and 18b may comprise the same fibers as those absorbent
fibers 18 described above with regard to the first embodiment of
the present invention. The absorbent fibers 18a and 18b may be the
same fiber type or may be different fibers types (i.e. a mixture of
fibers). In addition, a first absorbent fiber mixture (or
individual fiber) may be employed in the first plurality of fibers
18a and different absorbent fiber mixture (or individual fiber) may
be employed in the second plurality of fibers 18b.
[0035] The individual fibers 14 may be the same as the fibers 14
described above with regard to the first embodiment. In addition
the individual fibers 14 may be the same fiber type (i.e. a single
fiber type) or different fiber types (i.e. a mixture of
fibers).
[0036] In the particular embodiment of the invention shown in FIG.
5, the first layer 52 is arranged in spaced relationship to the
second layer 54. The absorbent material 10b may optionally further
include superabsorbent polymer material 46 dispersed within the
fiber matrix 16 of the fibrous material 12. In the particular
embodiment of the invention shown in FIG. 5, the superabsorbent 46
is arranged in a layer 56 between the first layer 52 and second
layer 54 of the absorbent fibers 18a and 18b. Of course the
superabsorbent polymer material 46 may be omitted from the
absorbent material 10b if desired.
[0037] A method of making the absorbent material 10b will now be
described with reference to FIG. 6 which depicts a schematic
representation of an apparatus 19a for making the absorbent
material 10b. As shown in FIG. 6, a web of fibrous material 12 is
fed from a supply roll 20 and conveyed in a machine direction by a
plurality of rolls 22, 24 and 26. A gravity fed hopper 28, or the
like, is utilized to apply a selected amount of absorbent fibers
18a to a top surface 30 of the fibrous material 12. Thereafter, the
fibrous material 12 is further conveyed in a machine direction and
passed through a needlepunch apparatus 32 for impregnating the
absorbent fibers 18a within the fibrous material 12.
[0038] Thereafter the fibrous material 12 is further conveyed to a
superabsorbent application station 42. The superabsorbent
application station 42 comprises a gravity fed hopper 44 structured
and arranged to apply a selected amount of superabsorbent polymer
material 46 to a top surface 30 of the fibrous material 12. Of
course, any suitable means known to those of skill in the art, such
as a pressure fed nozzle or the like, may be used to apply the
superabsorbent polymer material 46 to the top surface 30 of the
fibrous material 12. After the superabsorbent polymer material 46
is applied to the top surface 30 of the fibrous material 12 the
fibrous material 12 is conveyed over a vacuum 50 that functions to
draw the superabsorbent polymer material 46 into the fiber matrix
16 of the fibrous material 12. Of course, if the inclusion of
superabsorbent polymer material 46 is not desired in the absorbent
material 10b, the superabsorbent application and vacuum step
described may be omitted from the described method.
[0039] After the fibrous material 12 is conveyed past the vacuum
50, the fibrous material 12 is conveyed by rolls 51 and 53 to a
second gravity fed hopper 28a, or the like, to apply a selected
amount of absorbent fibers 18b to a top surface 30 of the fibrous
material 12. Thereafter, the fibrous material 12 is further
conveyed in a machine direction by rolls 55 and 57 and passed
through a second needlepunch apparatus 32a for impregnating the
absorbent fibers 18b within the fibrous material 12.
[0040] Referring again to FIG. 6, after the absorbent material 10b
is conveyed past the needlepunch apparatus 32a the absorbent
material 10b is further conveyed in a machine direction by roll 59
and then may be arranged in a rolled form for storage or may be
further conveyed for incorporation into a disposable sanitary
absorbent products such as a sanitary napkin, pantiliner, tampons,
diaper, adult incontinence product, or the like.
Examples
[0041] Specific examples of the present invention are described
below.
Inventive Example #1
[0042] An absorbent material as described above with reference to
FIGS. 1 and 2 is made as follows. The fibrous material is a fibrous
nonwoven made by a card and bind process having a basis weight of
68 gsm, formed from 100% polyester fibers (6 denier), and having a
thickness of 3 mm. Given that the density of polyester is 1.38
g/cc, a 6 denier fiber has a nominal diameter of 25 .mu.m
(denier=density*0.0283 r.sup.2). The fibrous material includes a
latex binder present in the amount of 40% by weight. A fibrous
nonwoven material of this type is commercially available from
Kem-Wove, Inc., Charlotte, N.C. under product code SCN09-038. The
absorbent fibers comprise 100% viscose rayon having a denier of 4.
Rayon has a density of 1.5 g/cc thus the absorbent fibers have a
fiber diameter of 19 .mu.m. 150 gsm (g/m.sup.2) of the rayon fibers
are applied to a top surface of the fibrous nonwoven material and
impregnated within the material to a depth of 2.5 mm by means of
the needlepunch process described above with reference to FIG. 2.
The needles used in the needlepunch process have a barb depth "d"
of 12 .mu.m. The final absorbent material has a thickness of 2.7
mm.
Inventive Example #2
[0043] An absorbent material as described above with referenced to
FIGS. 5 and 6 is made as follows. The fibrous material is a fibrous
card and bind nonwoven material having a basis weight of 68 gsm,
formed from 100% polyester fibers (6 denier), and having a
thickness of 3 mm. Given that the density of polyester is 1.38
g/cc, a 6 denier fiber has a nominal diameter of 25 .mu.m
(denier=density*0.0283 r.sup.2). The fibrous material includes a
latex binder present in the amount of 40% by weight. A fibrous
nonwoven material of this type is commercially available from
Kem-Wove, Inc., Charlotte, N.C. under product code SCN09-038. The
first plurality of absorbent fibers comprises 100% viscose rayon
having a denier of 4. Rayon has a density of 1.5 g/cc thus the
absorbent fibers have a fiber diameter of 19 .mu.m. 75 gsm of the
rayon fibers are applied to a top surface of the fibrous nonwoven
material and impregnated within the material to a depth between 4.0
mm and 5.0 mm by means of a first needlepunch apparatus. The
needles used in the needlepunch process have a barb depth "d" of 12
.mu.m. Thereafter, the fibrous material is conveyed to a
superabsorbent application station. 40 gsm of superabsorbent (SA70
commercially available from Sumitomo Seika Chemicals Co., Ltd. Of
Osaka, Japan) is applied to a top surface of the fibrous material
via a gravity fed hopper. The superabsorbent is drawn into the
fibrous material at a depth between 3.0 mm and 4.0 mm by means of a
vacuum. Thereafter, the fibrous material 12 is conveyed to a second
gravity fed hopper to apply a selected amount of a second plurality
of absorbent fibers to a top surface of the fibrous material. The
second plurality of absorbent fibers comprises 100% viscose rayon
having a denier of 4. Rayon has a density of 1.5 g/cc thus the
absorbent fibers have a fiber diameter of 19 .mu.m. 75 gsm of the
rayon fibers are applied to a top surface of the fibrous nonwoven
material and impregnated within the material to a depth between 1.0
mm and 3.0 mm by means of a second needlepunch apparatus. The
needles used in the second needlepunch process have a barb depth
"d" of 12 .mu.m. The final absorbent material has a thickness of
2.5 mm.
[0044] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various other changes and modifications can
be made without departing from the spirit and scope of the
invention. It is therefore intended to cover in the appended claims
all such changes and modifications that are within the scope of the
invention.
* * * * *