US 3628876 A
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Description (OCR text may contain errors)
United States Patent Primary Examiner- Daniel Blum AitorneyPendleton, Neuman, Williams & Anderson 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 Inventors Robert S. Casey; 3,051,993 Lynn P. Martin, both of Fort Madlson, 3,058,166 3,094,736  Appl. No. 754,161 3 1 1 702  Filed June 21,1968 3 145 4 2  Patented Dec. 21, 1971 3 232 05  Assignee Textron, Inc.
Providence, RJ. Continuation-impart 01 application Ser. No. 4423 244,196, Dec. 12, 1962, now abandoned. 860,387 This application June 21, 1968, Ser. No. 873,178 754,161 1,160,331
 WRITING IMPLEMENT 6 Claims, 2 Drawing Figs.
 U.S. Cl. 401/198  Int. Cl 1143111/00, B43k 5/18  Field oiSearch 401/198, 199, 206
 References Cited UNITED STATES PATENTS 1,457,875 6/1923 Coates 120/45 2,396,058 3/1946 Rath 120I45.6 2,684,052 7/1954 Rickmeyer 120/50 X 2,702,021 2/1955 Rickmeyer 120/50 3,015,855 l/1962 Merkel 264/127 3,022,542 2/1962 Davis 401/198 UX 3,048,537 8/1962 Pall et al. 401/198 UX point.
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 defonnation of the point in en gagement 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 WRITING IMPLEMENT This application is a continuation of application Ser. No. 244,196 filed Dec. 12, I962, now abandoned.
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. I
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 I 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,
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 implementgripping 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 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 providesa 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. I 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 22 of FIG. 1.
Referring particularly to FIG. I, 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 I4 is provided with a rearwardly extending reduced collar 16 which is threadedly engaged with the open end 18 of the barrel l2.
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 I2 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 I2.
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 I upper cylindrical portion 26 and a forwardly extending reduced cylindrical portion 28, the cylindrical portions being writing surface whereby the width of line may be varied by the user.
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 membenand 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 H6. 2, the applicator 24 consists of a material. Preferably the material is selected from the group of I 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, US. Pat. No. 3,05 L993 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 F. and 500 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 dis solved 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.
ln 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 materialis 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 costto the ultimate user while providing a superior product.
Applicators constructed of fused particulate plastic material 7 in accordance with this invention exhibit superior writing characteristics as well as substantially increased service life, as compared to felt applicators inpresent use. 7
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 betweenabout 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 ata 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 to microns, and it is,
plicator 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 7 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.
ln 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 thepresent 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 thevpresent invention were found to hold their shape much longer than felt and to wear ata 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.
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 percent.