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Patent 2560512 Summary

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(12) Patent: (11) CA 2560512
(54) English Title: MONOFILAMENTS WITH SPLIT ENDS
(54) French Title: MONOFILAMENTS A EXTREMITES FENDUES
Status: Deemed expired
Bibliographic Data
(51) International Patent Classification (IPC):
  • A46D 1/00 (2006.01)
  • B29C 48/345 (2019.01)
  • A46D 1/05 (2006.01)
  • A46D 1/06 (2006.01)
  • D01D 5/08 (2006.01)
  • D01F 6/58 (2006.01)
  • A46B 9/04 (2006.01)
(72) Inventors :
  • RACKLEY, ROBERT L. (United States of America)
(73) Owners :
  • E.I. DU PONT DE NEMOURS AND COMPANY (United States of America)
(71) Applicants :
  • E. I. DU PONT DE NEMOURS AND COMPANY (United States of America)
(74) Agent: TORYS LLP
(74) Associate agent:
(45) Issued: 2009-07-07
(22) Filed Date: 1997-04-24
(41) Open to Public Inspection: 1998-10-29
Examination requested: 2006-08-25
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): No

(30) Application Priority Data: None

Abstracts

English Abstract

Monofilaments with split ends. The monofilaments can be used to form toothbrush bristles having flagged or feathered tips. Each of the monofilaments has a plurality of internal fusion lines and at least four voids, wherein the voids comprise between 5 and 20 % of the cross-sectional area of the monofilaments. Preferably, the monofilaments each have a diameter in a range of 0.0025 to 0.012 inches, and have a hexalocular or an octalocular configuration. The monofilaments are manufactured by extruding a plurality of thermoplastic polymeric streams, rotating a plurality of cutting blades above 1000 rpm, and placing a plurality of cutting blades in contact with end portions of the plurality of thermoplastic polymeric streams to form split ends.


French Abstract

Monofilaments à pointes fourchues pouvant servir à faire des poils de brosse à dents aux pointes effilées ou assouplies. Chaque monofilament comporte plusieurs lignes internes de fusion et au moins quatre parties vides qui constituent de 5 à 20 % de la section transversale des monofilaments. Idéalement, les monofilaments présentent chacun un diamètre de 0,0025 à 0,012 pouce et ont une configuration à 6 ou 8 parties évidées. Les monofilaments sont fabriqués par l'extrusion de plusieurs flux thermoplastiques polymériques, la rotation de plusieurs lames de coupe à plus de 1000 tours/minute et la mise en contact de plusieurs lames de coupe avec les extrémités des flux thermoplastiques polymériques de façon à former des pointes fourchues.

Claims

Note: Claims are shown in the official language in which they were submitted.





10



What is claimed is:


1. A brush monofilament having a portion with a plurality of internal fusion
lines
and at least four voids, wherein said voids occupy between 5 and 20% of a
cross-
sectional area of the monofilament.


2. The brush monofilament of claim 1, wherein said monofilament is a
toothbrush bristle.


3. The brush monofilament of claim 1 or claim 2, wherein said monofilament is
made of a thermoplastic polymeric material.


4. The brush monofilament of claim 3, wherein said thermoplastic polymeric
material is selected from the group consisting of nylon 610, nylon 612, a
polyamide,
and polybutylene terephthalate.


5. The brush monofilament of any one of claims 1 to 4, wherein said brush
monofilament has six voids.


6. The brush monofilament of any one of claims 1 to 4, wherein said brush
monofilament has eight voids.


7. The brush monofilament of any one of claims 1 to 6, wherein said brush
monofilament has a near circular outer shape.


8. The brush monofilament of claims 1 to 7, wherein said brush monofilament
has an outer diameter in a range of 0.0064 to 0.030 cm.


9. A toothbrush comprising a plurality of brush monofilaments of any one of
claims 1 to 8.


Description

Note: Descriptions are shown in the official language in which they were submitted.



CA 02560512 1997-04-24

-1-
MONOITLEIMENTS WITH SPLIT ENDS
BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates generally to monofilaments, and more
particularly to monofilaments having split ends, which may be used for example
as
toothbrush bristles.

2. Description of the Related Art
Thermoplastic polymers have long been used to fonn brush
bristles in a wide variety of configurations. To increase the effectiveness of
these
brushes, the ends of such bristles have been split or "feathered" to provide a
soft
bristle tip. In the past, however, various difficulties have been encountered
in
splitting bristle tips.
In particular, various techniques have been used to split paintbrush
bristles to improve painting performance. Such procedures have been
particularly
suited to paintbrush bristles because long splits which propagate along a
large
portion (up to one inch) are particularly desirable. With certain brushes,
however,
only splitting of the tips is desirable. For example, the length of a typical
toothbrush bristle is about (or less than) one half inch. If splitting were to
occur
along a large portion of a toothbrush bristle, the bristles would not be
sufficiently
rigid to adequately clean teeth. Accordingly, currently available splitting
techniques fail to adequately address difficulties associated with splitting
the tips of
toothbrush bristles and other bristles in which long splits are undesirable.

SUMMARY OF THE INVENTION
This invention relates to a monoflament having a portion
with a plurality of internal fusion lines and at least four voids, wherein the
voids
comprise between 5 and 20% of the cross-sectional area of the monofilament.
This invention also relates to a monofilament having a


CA 02560512 1997-04-24

2-
diameter in a range of 0.0025 to 0.012 i.nches, wherein the nionofilanient has
a
hexalocular, an octalocular, or a near circular shape.
In addition, this invention relates to a method of
manufacturing extruded nionofilarnents having split ends, including the steps
of
extruding a plurality of thermoplastic polymeric streams to form a plurality
of
monofilaments, spinning a plurality of cutting blades above 1000 rpm, and
placing
a plurality of cutting blades in contact with end portions of the
nionofilaments to
fonn split ends. In one embodiment of the present invention, the blades are
spun
at or near the natural frequency of the monofilaments.

BRIEF DESCRIPTION OF THE DRAWINGS
Fig. la is a cross-sectional view of a hexalocular monofilament of
the present invention.
Fig. lb is a cross-sectional view of a spinnerette capillary used to
extrude the monofilament of Fig la.
Fig. 2a is a cross-sectional view of another hexalocular
monofilament of the present invention.

Fig. 2b is a cross-sectional view of a spinnerette capillaiy used to
extrude the nionofilament of Fig 2a.

Fig. 3a is a cross-sectional view of another hexalocular
monofilament of the present invention.

Fig. 3b is a cross-sectional view of a spinnerette capillary used to
extrude the monofilarnent of Fig 3a.

Fig. 4a is a cross-sectional view of another hexalocular
monofilament of the present invention.

Fig. 4b is a cross-sectional view of a spinnerette capillary used to
extrude the nionofilameiit of Fig 4a.

Fig. 5a is a cross-sectional view of another hexalocular
monofilament of the present invention.

Fig. 5b is a cross-sectional view of a spinnerette capillary used to


CA 02560512 1997-04-24

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extrude the monofilament of Fig 5a.
Fig. 6a is a front view of a spinnerette having a plurality of
spinnerette capillary locations.
Fig. 6b is a side view of the spinnerette of Fig. 6a.
Fig. 7a is a plan view of a blade used in manufacturing a
rnonofilament havirg split ends.
Fig. 7b is a front view of a structure having three blades mounted on
a conimon shaft for use in splitting the ends of the monofilaments of the
present

ulvention.
Fig. 7c is a side view of the structure of Figure 7b.
Fig. 8 is a graph of the natural frequency for a 612 monofilament
with a 550,000 psi modulus and various lengths and diameters.
Fig. 9 is a perspective view of a toothbrush having a plurality of
feathered bristles.

Fig. 10 is a side view of a plurality of bristles with split ends that
produce a plurality of soft fine tips.
Fig. 11 is a side view of a comparison of a feathered toothbrush
bristle which spreads-out on a tooth surface witli an ordinary solid tip which
provides only a single contact point.
Fig. 12 is a view of feathered toothbrush bristles which penetrate
deeper at the gum line for better cleaning without hurting the guni of a
patient.
Fig. 13 is a cross-sectional view of an octalocular nionofilarnent in
accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
OF THE PRESENT INVENTION
Wluch reference to the drawings, several embodiments of the present
invention, and their corresponding method of manufacture, will now be
described
in greater detail. Which reference to Figs. la, 2a, 3a, 4a and 5a, examples of
a
monofilament having a hexalocular shape are shown. Such shapes were achieved


CA 02560512 2006-08-25

-4-
through an extrusion process using the respective spinnerette capillaries of
Figs.
1 b, 2b, 3b, 4b and 5b. Such monofilaments were prepared by the fusion of six
polymer streams. Each of these monofilaments 10 include a plurality, of voids
20
and a plurality of weld or fusion lines. The voids result in a void content of
between 5 and 20% of the cross-sectional area of the monofilaments.
The brush bristle of the present invention can be prepared from a
wide variety of thermoplastic polymeric materials including polyamides,
polyesters
and polyolefins.
Polyamides for use in brush manufacturing including nylon 6,6,
nylon 610 (polyhexamethylene sebaccamide), and nylon 6I2 (hexamethylene.
diamine). Polyesters which have been found particularly well suited to bristle
manufacture include polybutylene terephthalate and polyethylene terephthalate.
A
polyolefin which has been found particularly well-suited to bristle
manufacture is
polypropylene.
The overall diameter, or overal] maximum cross-sectional
dimension, of the brush bristles of the present invention is in the range of
0.0025
to 0.012 inches (0.064 to 0.3 mm).
The bristles of the present invention are preferably forined by
extruding six or more individual streams of polymeric material from a
spinnerette
including the spinnerette capillaries shown in Figs lb, 2b, 3b, 4b, and Sb,
and
joining the streams to form a single filament. A spinnerette, such as the one
shown in Figures 6a and 6b, includes a plurality of spinnerette capillaries.
With
reference to Flgs. lb, 2b, 3b, and Sb, in the extrusion of the thermoplastic
polymer streams, the polymer is extruded through openings 40. The fusion of
the
streams results in fusion lines at the interface of the individual streams,
and the
formation of longitudinal voids along the fusion lines. The general
configuration
of the voids can vary widely.

After extrusion of the thermoplastic polymer streams at elevated
temperatures into a single filament, the nionofilament is quenched and then
drawn
as generally described, for example, in U.S. Pat. No. 2,418,492<


CA 02560512 2006-08-25

-5-
0

After extrusion and quencliing of the monofilament, the filament is
oriented by stretching to iniprove the longitudinal strength. In addition, the
filament can be subjected to other treatments to improve physical properties,
such
as treatment with saturated steam as described in U.S. patent No. 3,595,952,

The fila.ment may be heat set after drawing for good bend recovery.
The heat setting can be carried out either in a gas such as by blowing hot air
over
the filament, or a liquid bath such as by passing the filament through a bath
of oil.
The filaments are then cut into lengths suitable for brush manufacture. The
individual bristles are then gathered into bundles, the bundles are tufted
'uito
brushes, and the brushes are tipped and flagged by a procedure described
below.
With reference to Fig. 7a, a plan view of a cutting blade for use in
splitting the ends of the bristle of the present invention is shown. An
arrangement
of, three such blades which are separated by spacers on a common shaft by
about
3/16 of an inch and which are approximately rotated from one another by 120
degrees is shown in Figs. 7b and 7c. It has been found that by rotating such a
blade above 1000 rpm and placing such a blade in contact with the bristles
achieves
a fine feathering (splitting) effect. In one example of the present invention,
the
blades are rotated at 30,000 rpm with a router motor. The interference between
the bristle and the blade is varied depending on the depth of the split
desired,
although it has been found that 1/8 to 1/4 of an inch is preferable.
Essentially,.by
spinning the blades at a high rate of speed and placiiig the blades in contact
with
the bristle tips, a fast and violent bristle cutting action is achieved,
thereby causing
optimal bristle splitting.

It has also been found that by rotating the blades at or near the
natural frequency of a monofilament will obtain optimal splitting of the
bristles.
The natural frequency of a uniform beam is

Natura.l Frequency = A FEI


CA 02560512 1997-04-24

6-
0

where A=3.52 for a cantilever beam;
d
I= area rnoment of inertia 64 5

E is Young's Modulus of Elasticity; is mass per unit length; and 1= length.
The natural frequency is usually stated in radians per second which can also
be
expressed in revolutioris per minute by dividing by 2r and rnuitiplying by 60
seconds per ininute.
With reference to Fig. 8, a graph of the natural frequency for a 612
monoGlarnent bristle with a 550,000 psi modulus and various lengths and
diameters
is shown.

The monofilatnent bristles of the present invention produce a larger
number of smaller ends ("flags") than previously known monofilament bristles
of
the same diarneter. The bristles exhibit excellent durability and
cleanability, and
are particularly useful as toothbrush bristles to produce remarkably soft,
fine tips.
By using such a technique, the bristles of the present invention are split
rather thaii
end rounded to give a plurality of smaller ends that scrub the guigival area
more
effectively. It has also be found that the rnore dense area achieved by such
flagged
ends scrub major tooth ar=eas better by keeping toothpaste in contact with the
tooth
surface as well as achieving a softer feel when contact is made with soft
tissue in
the mouth.
With reference to Fig. 9, a perspective view of a toothbnrsti having
a plurality of feathered bristles is shown. Witli reference to Fig. 10, a
plurality of
bristles with split ends that produce a plurality of soft fine tips is also
shown.
These feathered filaments spread-out on tooth surfaces to provide a plurality
of
contact points, unlike ordinary solid tips which provide only one contact
point. A
comparison of these plurality of contact points to the single contact point of
a solid
tip is shown in Fig. 11. The fine feathered filaments of ttie present
invention also
produce a greater atid deeper penetration at the gum line for better cleaning
without


CA 02560512 1997-04-24
-7-
0
hurting the gum line of a patient. Such deeper penetration at the gum line is
shown in Fig. 12. Accordingly, these soft filament tips carry sweeping power
action along with a beneficial interdental and gumline cleaning. In fact, it
has been
found that such feathered tips reach farther between teeth, provide better
cleaning
coverage than ordinary soft filament tips because of the increase in contact
surfaces, and thus holds toothpaste in contact with teeth. Such an arrangement
also
provides a unique cushioning effect at the tips whicli adds extra softness to
the
brush. Such softness reduces bleeding of the gums during brusliing. Moreover,
such bristles have proven to be as hygienic as round filaments.
Although the present invention has been described with reference to
a hexalocular bristle structure liaving six voids, it has also been found that
an
octalocular bristle structure (having eight voids) provides numerous
beneficial
effects. Such an octalocular bristle is shown in Figure 13. It is also to be
understood that although six and eight streams have been used to achieve
hexalocular and octalocular structures, respectively, a greater number of
streams
may be used to produce additional structures having a corresponding greater
number of voids. The outer shape of such hexalocular, octalocular or other
structures may be manufactured so as to have a circular or near circular
shape.
Such a near circular outer shape is shown in Figure 13.

The percetitage of the cross-sectional area occupied by the voids in
the monofitaments is determined by the size, location, symmetry and shape of
the
voids. It has been found that a certain level of hollow space (voids) will
result ici
an optiinal splitting of brushes having relatively short lengths, such as
toothbrushes. The voids optimally result in a void content of between 5 and 20
%
of the cross-sectional area of the monofilaments. With such brushes, if the
voids
are too small, such as the voids disclosed in U.S. Patent No. 5,128,208, any
feathering effect would result in broken bristle ends rather than in achieving
feathering. If the voids are too large, such as the voids disclosed in U.S.
Patent
No. 4,279,053, the bristle would feather easily, but the splits would likely
propagate down the bristle during use. With use as a toothbrush bristle, it is


CA 02560512 1997-04-24

-8-
important that the tips of the bristles be split without the split propagating
down the
filament, either during manufacture or use by a patient. This may also be true
of
other types of brushes, depending on the particular use of the brush and/or
length
of the bristles.
With regard to the location of the voids within the monofilainent, the
voids should be located about 1/2 way between the center and the outside edge.
It
has also been found that a longer and slender void achieves a greater flagging
effect than a rounded void.
It is also to be noted that the voids may be either symmetrical or
asymmetrical, although it is to be noted that an asymmetrical void may have a
natural curvature which is often undesirable in particular uses, such as a
toothbrush. Preferably, openings 40 of the spinnerette capilaries, as shown in
Figs. lb, 2b, 3b, have a radius of curvature r in the range of 5 to 12 mils.
Openings 40 of the spinnerette capillary of Fig. 2b have an internal radius
(or
radius of curvature) of 9 mils, while the openings of the spinnerette
capillary of
Fig. 3b have a radius of 8 mils. Interestingly, use of the spinnerette
capillary of
Figure 2b results in the asymmetrical monofilament of Fig. 2a, while use of
the
spinnerette capillary of Fig. 3b results in the symmetrical monofilament of
Fig. 3a.
It is important to note that the asymmetrical monofilament of Fig. 2a is not
due to
problems in the symmetry of the design, but with the large size of the lobes.
Wiff
large lobes, the streams are not knitted together as the center is pulled. As
such,
insufficient space is left for two of the streams to be pulled into the
monofilament.

The void content is determined on the basis of the weight of the
hollow bristle and the weight of a hypothetical solid bristle of the same
exterior
configuration, according to the following formula:

% Void Content = 10 0 (1- weight of hollow bristlel
weight of solid bristle
Although the present invention has been described in terms of certain


CA 02560512 2006-08-25

-9-
0
preferred embodiments, other embodiments that are apparent to those of
ordinar},
skill in the art are also intended to be within the scope of the preseiit
invention.
Accordingly, the scope of the present invention is intended to be limited only
by
the claims appended thereto.
10

20
30

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Administrative Status

Title Date
Forecasted Issue Date 2009-07-07
(22) Filed 1997-04-24
(41) Open to Public Inspection 1998-10-29
Examination Requested 2006-08-25
(45) Issued 2009-07-07
Deemed Expired 2017-04-24

Abandonment History

There is no abandonment history.

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Request for Examination $800.00 2006-08-25
Registration of a document - section 124 $100.00 2006-08-25
Application Fee $400.00 2006-08-25
Maintenance Fee - Application - New Act 2 1999-04-26 $100.00 2006-08-25
Maintenance Fee - Application - New Act 3 2000-04-25 $100.00 2006-08-25
Maintenance Fee - Application - New Act 4 2001-04-24 $100.00 2006-08-25
Maintenance Fee - Application - New Act 5 2002-04-24 $200.00 2006-08-25
Maintenance Fee - Application - New Act 6 2003-04-24 $200.00 2006-08-25
Maintenance Fee - Application - New Act 7 2004-04-26 $200.00 2006-08-25
Maintenance Fee - Application - New Act 8 2005-04-25 $200.00 2006-08-25
Maintenance Fee - Application - New Act 9 2006-04-24 $200.00 2006-08-25
Maintenance Fee - Application - New Act 10 2007-04-24 $250.00 2007-03-29
Maintenance Fee - Application - New Act 11 2008-04-24 $250.00 2008-04-03
Maintenance Fee - Application - New Act 12 2009-04-24 $250.00 2009-04-07
Final Fee $300.00 2009-04-27
Maintenance Fee - Patent - New Act 13 2010-04-26 $250.00 2010-03-19
Maintenance Fee - Patent - New Act 14 2011-04-26 $250.00 2011-03-09
Maintenance Fee - Patent - New Act 15 2012-04-24 $450.00 2012-03-14
Maintenance Fee - Patent - New Act 16 2013-04-24 $450.00 2013-03-14
Maintenance Fee - Patent - New Act 17 2014-04-24 $450.00 2014-03-12
Maintenance Fee - Patent - New Act 18 2015-04-24 $450.00 2015-04-01
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
E.I. DU PONT DE NEMOURS AND COMPANY
Past Owners on Record
RACKLEY, ROBERT L.
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Abstract 1997-04-24 1 17
Description 1997-04-24 9 349
Claims 1997-04-24 6 138
Description 2006-08-25 9 350
Claims 2006-08-25 3 85
Representative Drawing 2006-11-17 1 6
Cover Page 2006-11-20 1 38
Claims 2007-06-27 2 41
Drawings 2007-06-27 7 76
Claims 2008-06-17 1 28
Drawings 2008-06-17 7 182
Representative Drawing 2009-06-25 1 5
Cover Page 2009-06-25 1 37
Drawings 1997-04-24 7 88
Fees 2008-04-03 1 37
Prosecution-Amendment 2008-06-17 5 262
Correspondence 2006-10-19 1 14
Correspondence 2006-10-24 1 36
Prosecution-Amendment 2006-08-25 8 234
Assignment 1997-04-24 3 110
Correspondence 2006-11-08 1 16
Prosecution-Amendment 2006-12-27 3 120
Prosecution-Amendment 2007-06-27 6 175
Correspondence 2007-09-19 19 269
Correspondence 2007-10-09 1 14
Correspondence 2007-10-15 2 43
Prosecution-Amendment 2007-12-17 3 95
Correspondence 2009-04-27 1 35