U.S. patent number 3,628,876 [Application Number 04/754,161] was granted by the patent office on 1971-12-21 for writing implement.
This patent grant is currently assigned to Textron, Inc.. Invention is credited to Robert S. Casey, Lynn P. Martin.
United States Patent |
3,628,876 |
Casey , et al. |
December 21, 1971 |
WRITING IMPLEMENT
Abstract
The writing implement has a fluid reservoir, a rodlike
applicator for conducting fluid from the reservoir to a writing
surface and means supporting the applicator against axial movement
under normal writing pressure. The applicator comprises a
substantially continuous matrix of a wear-resistant, resilient,
synthetic polymer having therethroughout a plurality of randomly
disposed interconnected voids providing tortuous passageways of a
size sufficient to permit capillary movement of a writing fluid
therethrough upon contact of the point with the writing surface,
the matrix having sufficient flexibility to permit resilient
deformation of the point in engagement with the writing surface
under normal writing pressure and having sufficient stiffness to
maintain the forward end thereof in substantial axial alignment
with the rearward end under normal writing pressure applied
angularly to the point.
Inventors: |
Casey; Robert S. (Fort Madison,
IA), Martin; Lynn P. (Fort Madison, IA) |
Assignee: |
Textron, Inc. (Providence,
RI)
|
Family
ID: |
26936382 |
Appl.
No.: |
04/754,161 |
Filed: |
June 21, 1968 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
244196 |
Dec 12, 1962 |
|
|
|
|
Current U.S.
Class: |
401/138; 401/198;
401/206 |
Current CPC
Class: |
B43K
5/1845 (20130101) |
Current International
Class: |
B43K
5/00 (20060101); B43K 5/18 (20060101); B43k
001/00 (); B43k 005/18 () |
Field of
Search: |
;401/198,199,206 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
442,310 |
|
Nov 1948 |
|
IT |
|
860,387 |
|
Feb 1957 |
|
GB |
|
873,178 |
|
Jul 1961 |
|
GB |
|
1,160,331 |
|
Feb 1958 |
|
FR |
|
Primary Examiner: Blum; Daniel
Parent Case Text
This application is a continuation of application Ser. No. 244,196
filed Dec. 12, 1962, now abandoned.
Claims
What is claimed is:
1. In a writing implement, a reservoir for writing fluid, an
apertured gripping section, valve means between said reservoir and
the aperture of said gripping section axially movable between a
rearward open position and a forward closed position, and spring
means resiliently urging said valve means toward said closed
position for interrupting the flow of writing fluid from said
reservoir into said gripping section aperture, an improved rodlike
applicator disposed in said gripping section aperture for fluid
communication with the writing fluid in said reservoir and
extending forwardly from said gripping section for engagement with
a writing surface, said applicator comprising a substantially
continuous nonfibrous matrix of a resilient synthetic polymer
having therethroughout a plurality of interconnecting voids
providing capillary passageways of a size sufficient to permit
capillary movement of the writing fluid therethrough upon contact
of the applicator with the writing surface, said tip having
sufficient flexibility to permit resilient deformation of the end
thereof in engagement with the writing surface under normal writing
pressure and having sufficient stiffness to permit the transmission
of axial force therethrough to effect opening of said valve means
against the resistance of said spring means.
2. In a writing implement a reservoir for writing fluid, an
apertured section extending forwardly of said reservoir, an
improved rodlike applicator having a rearward end disposed in said
section aperture for fluid communication with the writing fluid in
said reservoir, and a forward end extending substantially beyond
said section and terminating in a point formed for engagement with
a writing surface, and means in said section engaging said rearward
end and supporting said applicator against axial movement upon the
application of writing pressure on said point, said applicator
comprising a substantially continuous nonfibrous matrix of a
wear-resistant, resilient, synthetic polymer having therethroughout
a plurality of randomly disposed interconnected voids providing
tortuous passageways of a size sufficient to permit capillary
movement of a writing fluid therethrough upon contact of the point
with the writing surface, said matrix having sufficient flexibility
to permit resilient deformation of the point in engagement with the
writing surface under normal writing pressure and having sufficient
stiffness to maintain said forward end in substantial axial
alignment with said rearward end under normal writing pressure
applied angularly to said point.
3. The structure of claim 2 wherein said applicator is frictionally
held in position within said section.
4. The structure of claim 2 wherein the size of the voids varies
throughout the cross section of the applicator with the voids at
the surface of said applicator being of smaller size and greater
capillarity than the voids in the remainder of said applicator.
5. The structure of claim 2 wherein said synthetic polymer is
selected from the group consisting of polyolefins and
polyamides.
6. The structure of claim 2 wherein the void volume is between
about 40 and about 70 percent.
Description
This invention relates to a writing or marking implement and has
special reference to a porous applicator member for conducting a
liquid marking medium from the body of the implement onto a writing
surface.
The applicator or writing tip used in the conventional marking
implement consists of an elongate member formed of wool or similar
fibers treated with a sizing material to promote adhesion and
stiffness, and compressed mechanically to provide a relatively
rigid felt structure capable of transferring ink from a reservoir
to a writing surface. Such a compressed felt applicator defines
throughout its structure a multiplicity of relatively minute
interconnecting capillary passages which permit the necessary
controlled fluid movement from one end of the applicator to the
other as the applicator engages and transfers the ink to a writing
surface.
While felt has been used quite universally for marking tips in the
past, this material does have a number of drawbacks and does
present problems which have not been resolved satisfactorily prior
to the present invention. As is known in the art, the usual manner
of producing a felt applicator first involves the step of
compressing a quantity of fibers into a relatively dense block or
sheet, the compression of the fibers resulting in what might be
considered a mechanical binding of the individual fibers generally
aided by the presence of the sizing material. From such sheets or
blocks of felt material, "blanks" for individual applicators are
generally formed by a cutting or stamping operation, and these
blanks are then ground to the final desired dimensions and shape.
Since this process results in the production of a substantial
amount of waste material and necessitates special handling
techniques, the cost of producing felt applicators is necessarily
relatively high.
In addition to the high cost of the usual applicator, the felt
material tends to deform and wear quite quickly in use,
necessitating frequent replacement. Further, felt does not provide
a smooth feel in writing, and in many instances will produce a very
objectionable "squeak" as it is moved over a writing surface.
These problems have long been recognized in the art, with various
suggestions being advanced in an effort to eliminate them. For
instance, it has been proposed to provide an applicator formed of a
ceramic material which is subject to little wear when used on the
usual writing surface. However, such applicators have not proven
commercially practicable primarily because of their extreme
rigidity, whereby little or no variation in line width can be
realized during writing. Also, of course, a ceramic applicator
would lack the degree of resilience necessary to provide the
desired frictional engagement with the surrounding portions of the
gripping section, and thus, it would be necessary to mechanically
connect such ceramic applicator in place.
Accordingly, it is one object of this invention to provide an
improved writing and marking implement having good writing
characteristics and a long service life.
It is another object of the invention to provide a marking or
writing implement having an improved long-wearing applicator which
may be easily and inexpensively produced.
Still another object of this invention is the provision of a
porous, fluid-conducting applicator for a valved marking implement,
which applicator has both sufficient resilience to assure
frictional engagement with the surrounding portions of the
implement-gripping section and yet sufficient strength and
stiffness to prevent excessive bending in use and to assure a
continued capability for transmitting a valve-opening force
therethrough.
Yet another object of this invention is to provide a marking
applicator defined by a fluid-conducting homogeneous porous mass of
material which is long-wearing, relatively free from permanent
distortion under normal use, and sufficiently resilient to permit
compression at the point of contact with a writing surface whereby
the width of line may be varied by the user.
Yet an additional object of the present invention is to provide a
marking tip which is formed of a synthetic material, provides a
smooth writing feel, may be inexpensively manufactured and provides
a greatly increased service life.
Further objects of this invention will be apparent from the
following description and claims when taken with the accompanying
drawings.
In accordance with the present invention there is provided in a
marking implement a semiflexible marking applicator consisting of a
cohesive matrix of a synthetic polymeric material having
therethroughout interconnected pores or cells of a size which will
retain a charge of liquid marking fluid by capillary attraction but
will readily release such marking fluid upon contact of the
applicator tip with a marking surface.
The matrix preferably consists of a multiplicity of solid particles
of a generally predetermined size which have been sintered or
otherwise fused primarily at their points of surface contact to
provide the interconnected pores which in turn provide the desired
fluid control and flow. The polymeric material from which the
matrix is formed should be inert, that is, it should not react
adversely in the presence of the constituents of the marking fluid
being used. Moreover, the matrix material should be of a tough and
semirigid, semiflexible nature, and it should have good resistance
to abrasion and wear. For this purpose, polyethylene granules have
been found to serve satisfactorily, although it is understood that
the present invention is not limited to this particular material
since other types of solid inert polymeric materials may be
chosen.
The synthetic plastic powder or particles may be formed either as a
finished applicator or as an elongated rod which is then cut to
length and, if desired, provided with a tip of conical,
hemispherical, or like shape.
With reference to the drawings:
FIG. 1 is a longitudinal cross-sectional view of a marking
implement containing a marking tip constructed in accordance with
the present invention; and
FIG. 2 is a greatly enlarged cross-sectional view of a portion of
the marking tip as taken along line 2--2 of FIG. 1.
Referring particularly to FIG. 1, there is disclosed a marking
implement 10 of generally conventional construction, consisting of
a barrel portion 12 and an axially aligned gripping section 14. The
barrel and gripping section may be formed of any one of a number of
materials, such as a plastic or metal, which is inert to the ink
intended to be used therewith. The ink used is preferably water
based although inks having volatile solvent bases may be used. For
purposes of convenient assembly the gripping section 14 is provided
with a rearwardly extending reduced collar 16 which is threadedly
engaged with the open end 18 of the barrel 12.
While the barrel 12 and gripping section 14 generally may be
circular in configuration, it will be understood that other
cross-sectional configurations may be used. Also, the external
surface of the gripping section preferably is reduced in diameter
toward its forward or outer end, thereby providing a configuration
which is not only pleasing in appearance but permits unrestricted
viewing of the marking tip and of the mark as it is applied by the
tip to the writing surface.
The interior of the barrel 12 defines an ink reservoir 20 which is
arranged for communication with the interior of the gripping
section 14 through the open forward end 18 of the barrel 12.
While other arrangements may be used, the present embodiment
illustrates the gripping section as having a valve member 22
disposed between the reservoir 20 and a fluid-conducting applicator
24. The valve member 22 consists of an upper cylindrical portion 26
and a forwardly extending reduced cylindrical portion 28, the
cylindrical portions being connected by a frustoconical section 30
which is adapted to sealably engage an intermediate tapered seat 32
provided internally of the gripping section 14.
Extending rearwardly from the intermediate tapered seat 32 is a
concentric bore 34, and forwardly of the seat is a reduced bore 36
which defines a centrally disposed opening through the forward end
38 of the gripping section 14.
The valve member 22 is resiliently mounted for longitudinal
reciprocal movement between a closed position sealably engaging the
seat 32 and an open position spaced rearwardly of the seat, thereby
permitting movement of fluid and air between the applicator 24 and
the reservoir 20. The valve member 22 is urged toward its closed
position by a coil spring 40 having one end disposed in a recess 42
formed in the rearward surface of the valve member, and the other
end abutting an apertured washer 44 mounted within the bore 34. The
washer 44 is preferably threadedly retained within the bore 34, as
shown in the illustrated embodiment, although it may be held in
position by various other means such as by adhesive or
friction.
The marking applicator 24 is sized to slidingly engage the interior
surface of the reduced bore 36 with sufficient frictional contact
to insure that the applicator will not fall from or be jarred from
the bore 36 in normal usage. However, such frictional contact is
readily overcome to permit rearward movement of the applicator 24
and valve member 22 so that the applicator may be "loaded" or
charged with ink for deposit on a writing surface. As illustrated
in FIG. 1, the rearward end surface of the applicator 24 abuts the
forward end of the reduced cylindrical portion 28. Thus, rearward
axial movement of the applicator 24 will cause corresponding
movement of the valve member 22 toward its open position, and the
coil spring 40 will simultaneously urge the valve member 22 toward
its closed position and the applicator 24 toward a forward or
marking position. In the illustrated and preferred embodiment, the
action of the spring 40 against the valve member is sufficient to
insure that normal writing pressure will not effect rearward axial
movement of the applicator 24 and valve member 22, rather such
movement will occur only upon the conscious application of
additional pressure by the user for the purpose of effecting
re-inking of the applicator.
As shown best in FIG. 2, the applicator 24 consists of a cohesive
porous mass composed of a multiplicity of particles 46 which are
fused together at their points of contact to define therebetween
capillary-sized interconnecting pores or voids 48 which will not
only retain a charge of fluid, but permit such fluid to pass
therethrough and be withdrawn therefrom as the forward end of the
applicator 24 is moved across a writing surface.
The particles 46 are of a solid, inert synthetic polymeric
material. Preferably the material is selected from the group of
polymeric thermoplastic substances known as polyolefins and
polyamides. Exemplary of the polyolefins are polypropylene and
polyethylene including the so-called linear polymers thereof.
Exemplary of polyamides are nylons.
The fusion of the individual particles 46 to one another to form a
homogeneous porous mass may be effected by any one of several
processes which are known in the art. As an example, U.S. Pat. No.
3,051,993 teaches a process for producing a porous article by the
steps of confining a granular or particulate synthetic
thermoplastic material in a porous support, and subjecting the
material to a temperature between 300.degree. F. and 500.degree. F.
while concomitantly passing a stream of heated gas through the mass
of particles for a time sufficient to sinter or fuse the particles
at their points of contact while leaving a series of
interconnecting voids between the particles. Other processes for
producing the present applicator would include mixing of the
particles with a soluble binder or filler material, such as
granular table salt, sugar or potato starch, and shaping or molding
the resultant mixture by any of the usual forming techniques for
plastics. After the molding step has been completed, the filler
material may be leached from the mass by a suitable solvent, which
in the case of salt or sugar may be water. Other binders or fillers
may be employed, and the selection is limited only by the ability
of the material to remain in place during molding operation and to
be selectively dissolved or flushed from the molded structure
thereafter without adversely affecting the fused plastic matrix. As
an alternative forming process, a solvent may be forced through the
particulate material, either as a liquid or gas, and with or
without additional external heat, to effect temporary softening of
the particles and fusion at their points of contact.
In order to eliminate the necessity of further handling, it is
desirable to form the applicator 24 as a finished article in a form
or mold of the desired final configuration and size. Should it be
desired to pass a solvent or gas through the powdered or granular
material during the fusion process, the mold may be porous or
otherwise provided with minute apertures to permit passage of such
gas, although if a simple heating process is chosen, the mold may
be of an imperforate nature. Further, the applicator may be cut
from an elongate rod formed by extrusion of the particles through a
die opening of the desired size and configuration. In this event,
the fusion of the particles may be accomplished conveniently during
the extrusion operation by using the soluble filler
mixture-leaching process outlined hereabove.
One of the advantages realized as a result of the present invention
is the reduced expense of preparing the applicator. Felt
applicators cannot be formed in a final shape but, as pointed out
above, necessarily have to be cut or stamped from blocks or sheets
of compressed material, and then ground or otherwise finished to
provide the desired dimensions and tip configuration. Also, strips
of felt may be forced through a circular cutting die to provide an
elongate rod from which applicators subsequently are cut prior to
grinding of the tip. However, in such processes, a great deal of
felt material is discarded as waste and several operations are
required to produce the final article. Thus, the cost of the
finished felt applicator is substantially increased.
In the present invention, however, the applicator may be formed in
the final desired configuration, or it may be extruded in the
desired cross-sectional size. Either process very materially
reduces or completely eliminates any material waste thereby
decreasing the cost to the ultimate user while providing a superior
product.
Applicators constructed of fused particulate plastic material in
accordance with this invention exhibit superior writing
characteristics as well as substantially increased service life, as
compared to felt applicators in present use.
It is preferred that the applicator 24 be formed of polyethylene
since because of its resiliency, "toughness," and wear resistance,
this material has been found to have excellent marking
characteristics. However, the selection of the material used for
the applicator will to some extent be determined by the nature of
the marking ink being used. For example, certain chemicals, such as
aromatic hydrocarbons used in several commercial permanent marking
inks, adversely affect polyethylene and other synthetic plastic
materials, and for this reason a simple check or observation for
any adverse reaction between the ink and the proposed synthetic
material should be made. For a permanent-type ink a polyamide such
as nylon may be chosen because of its inert properties in the
presence of such ink.
The size (average cross-sectional diameter) of the pores should be
such as to permit a marking ink having a viscosity of between about
2 and about 5 centipoises to be drawn therethrough by capillary
action onto a marking surface. This pore size should range between
about 75 and about 250 microns because with a pore size much below
75 microns a marking ink of 2 to 5 centipoises will not tend to
flow at a sufficient rate for marking purposes, whereas if the pore
size is much above 250 the rate of flow therethrough will generally
be too great. Excellent results have been obtained with applicator
pore sizes in the range of 100 to 150 microns, and it is,
therefore, preferred that the pore size be in this range. The pore
size may be regulated easily by regulating the size of the
particles which are joined to form the matrix--the larger the
particles, the larger are the pores or voids therebetween. Pore
size may also be easily regulated by the size of the granules of
salt, sugar or the like if the soluble filler-leach process is used
to produce the applicators.
It should be pointed out that it is desirable to provide an
applicator wherein the ratio of pores to solid particles is fairly
substantial so that frequency of re-inking of the applicator may be
reduced to a minimum, and so that the required strength and
rigidity may be maintained. A void volume between about 40 and 70
percent has been found to provide a satisfactory reservoir of fluid
while still permitting sufficient rigidity of the polymer matrix to
prevent undue deformation of the applicator under writing and
valve-opening pressures. Also, the finished applicator should be
readily wettable by the ink. Thus, if a polyethylene applicator is
used with an aqueous ink, it should be treated with a wetting
agent, or alternately, it may be desirable to incorporate a wetting
agent in the ink.
If desired, the pore size can be varied throughout the cross
section of the applicator. For example, a somewhat more dense
surface may be provided to give tighter capillary pores and an even
longer wearing surface at the tip, with larger pores extending
through the central area of the applicator to permit rapid movement
of fluid therethrough. This may be accomplished at the time that
the material is fused, by controlling the compressive pressure on
the powder, whereby the surface areas are compressed somewhat more
than the interior mass. Also, by passing the final applicator
through a heated die, or by subjecting it to some equivalent
heating operation, the material at the surface of the applicator
may be caused to flow or "smear" to substantially or completely
close the surface pores. It is understood, of course, that in the
writing tip area at the forward end of the applicator, the pores
should remain open so that fluid may be withdrawn therefrom during
writing. However, the wall of the applicator rearwardly of the tip
may be closed in this fashion to reduce evaporation of fluid while
the marking device is in use, thereby reducing the amount of ink
ultimately consumed by the user during periods of employment of the
implement. When the marker is not being used, the applicator may be
isolated from the atmosphere by a removable cap of conventional
construction.
Due to the frictional relationship between a felt applicator and
the usual paper surface, the felt does not appear to move over the
surface in a smooth continuous motion, but instead appears to move
in a series of very minute "jerks" or steps which produce a
high-pitched "squeak" which is objectionable to a great many users.
With an applicator of the present invention, however, the writing
feel is extremely smooth and even, with no evidence of dragging or
"squeaking" while moving over a surface.
A further feature of the present applicator is that it exhibits
substantially less wear and permanent deformation than is exhibited
by the usual felt applicator thereby materially reducing the
required frequency of applicator replacement. Since felt depends
primarily upon a mechanical innerlocking between the felt fibers,
the fibers are dislodged relatively readily as movement occurs over
a surface, particularly where that surface may be quite rough.
Also, this mechanical innerlocking appears to permit some shifting
of the structure of the felt fibers upon deformation of the tip in
the area of contact with the writing surface. Apparently, as a
result of such shifting, the tip of a felt applicator tends to lose
its shape at a rate greater than could be attributed to actual loss
of material through wear. In other words, after compression of the
felt during writing, the depressed area does not appear to always
return to its original dimensions after release of pressure. Thus,
"wear" of a felt applicator is attributable not only to loss of the
material or fibers during writing, but also to permanent
deformation of the contact area under normal writing and
valve-actuating conditions.
In contrast, in the applicator of the present invention, the
particles of the applicator are actually fused together, which
fusion substantially eliminates any possibility of loss of material
due to mechanical disengagement. Thus, any wear which does occur,
occurs very gradually. Moreover, while the applicator can be
deformed to provide varying widths of line during writing, such
deformation is resilient rather than permanent and the tip will
return to its original dimensions upon removal of the writing or
valve-actuating force causing the deformation. Thus, an applicator
of the present invention not only will actually wear much better
than a felt applicator, but it will retain its original shape to a
much better extent. In a series of carefully controlled wear tests,
applicators constructed in accordance with the present invention
were found to hold their shape much longer than felt and to wear at
a rate of about one-half that of commercial felt applicators.
It will be understood that the above description has been made only
by way of example and that this invention is not to be limited to
one particular material or process of formation of the finished
applicator, since various materials and processes may be employed.
Accordingly, this invention is not to be limited to the embodiment
illustrated and described herein, as various modifications may be
made without departing from the true spirit and scope of the
invention as defined by the appended claims.
* * * * *