EP0667818B1 - Capillary writing medium reservoir system - Google Patents

Abstract

The invention(s) relate(s) to writing instruments and especially to capillary colorant reservoirs in said writing instruments. A process for producing said colorant reservoir is also proposed. The main problem in such colorant reservoirs is the storage time. During this time, the writing capacity of new writing instruments falls since the walls of the writing instruments are, if only slightly, permeable to solvents. In the long run a stored writing instrument thus dries out and loses the major proportion of its original writing capacity. To this end, an invention proposes to provide a colorant reservoir having an elongated reservoir body (20) made of fibrous material (21). It is surrounded by a sleeve (22) which is permeable to liquids and gases and gives the reservoir body (20) its shape. The colorant reservoir stores colorant to produce the (liquid) writing medium said colorant being stored between the fibres of the fibrous material (21) of the reservoir body (21) in dry form. A one or multi-part wick (1) projects from either side of the reservoir body (20). A process for producing said colorant reservoir is also proposed, according to which the elongated capillary fibrous body is surrounded by a gas and liquid-permeable but liquid-proof foil and the fibrous body thus surrounded is soaked in or with a colorant concentrate. The soaked fibrous body is drained off and dried. Then a one or multi-part rod-like wick (1) is introduced along it. The wick (1) is longer than the elongated fibrous body (20).

Description

The inventions relate to a capillary-writing material storage system for writing utensils, such as fiber pens, liners, markers, which consists of several individual memories which contain fiber material (claim 1). According to a further proposal, an inexpensive variant contains only one individual fiber material store (claim 2). The invention also relates to a capillary dye store - as one of said individual stores - for use in the above-mentioned writing instruments (claim 3). Finally, a method for producing said dye storage is also proposed (claim 7).

Writing instruments are known in various forms with liquid writing materials. The writing material storage chamber can consist of a refillable storage container or exchangeable cartridges. In the case of fiber pens, a capillary memory, for example a tampon or a fiber pack, is provided in the writing instrument housing and contains a predetermined supply of finished writing material. This stock is assigned to it during manufacture and determines the life of the writing instrument (cf. US 3,481,677). If you use the cartridges mentioned, there are environmental problems because the waste - usually plastic cartridges - must be disposed of.

If a built-in writing material storage is provided in writing instruments, which stores a predetermined amount of writing material, this amount is limited from the outset. After the previously stored amount of writing material has been dispensed, the writing instrument is empty and, like the cartridges, should be disposed of. In addition, there is the problem that the predetermined amount of writing material decreases due to aging, even when the writing instrument is not being used; in other words: when it is waiting for acceptance and sale on the shelves of retailers and wholesalers.

A refillable capillary-writing material storage system has become accessible to the professional world from WO 92/18339. It has the technical features (a) and (b) of claim 1, but not the feature group (c) and the proviso that the middle individual memory, which stores the color component, contains fiber material.

A marking or coloring pen ("marker") is described in US 3,993,409 (Hart). In two examples, markers are described there that have two individual memories. They are nested inside one another. One of the reservoirs is the writing tip (or "writing wick"), the other is the fluid reservoir. The latter is significantly larger than the former. At Hart, the individual storage tanks are in one another, not in a row; the size is also contrary to the teaching of claim 2. However, the writing wick at Hart also stores writing fluid and color pigment at the same time (cf. claim 2).

With regard to claim 3, US 3,993,409 (Hart) discloses the feature groups (a) and (c), but not the shell which is permeable to liquids and gases and which is also contained in feature group (a) of claim 7. Placing a cover around the Hart wick would be equivalent to the inoperability of the Hart markers, which are based on nested contact between the outside of the wick and the plug hole (hole) for their function.

It is an object of the invention (s) to give the writing instruments mentioned a longer service life and, in particular, a longer storage period and, nevertheless, to simplify the manufacture of the color memories.

This object is achieved by the technical teachings of the claims 1,2, 3 or. 7

With regard to the capillary-writing material storage system for the above-mentioned writing instruments (claim 1), the separation of the previously one memory into a plurality of fiber material stores is essential for the success according to the invention. At least three stores are provided, a rear, a front and the individual store in between. The latter stores the color content of the writing material in the fiber material in a dry form. This type of storage is timeless. A manufactured writing instrument can thus be stored for a long time without it drying out or without losing its predetermined writing capacity, because the dry color portion of the writing material cannot dry out further and a liquid portion which could evaporate or escape through walls does not exist. Before the writing instrument is put into use, the rear individual memory is then impregnated with a solution liquid from outside the writing instrument. It can be water or alcohol. From the rear individual store, the filled solution liquid passes through the wick - connecting the individual stores - into the middle fiber material-dye store, where the color fraction enters the solution liquid by capillary forces in order to reach the front individual store as a (colored) writing material that is in contact with the writing tip. The latter single memory - which can be smaller than the other memories - has the function of equalizing the writing material and always storing a certain but limited amount for immediate writing.

The capillary flow connection carries the concept according to the invention significantly, because a consumption of the writing material from the front individual storage leads to an automatic refilling of the front one due to the balancing forces from the extremely damp rear individual storage to the - mixing the color - middle individual storage to the emptying front individual storage Individual storage with writing material.

The previously mentioned separation of a memory into one A plurality of memories can be simplified in terms of costs without leaving the idea of storing dye dry in a dye store. The middle and lower individual storage can thus be combined into a coherent dye storage, which stores both the dry dye (the color pigments) and - after filling the pen - the liquid writing material. Only one additional store (the rear single store) is required, but this is not filled with fiber material, but rather represents a cavity (claim 2). The liquid is poured into this cavity, where it is briefly stored (buffered) and then slowly distributed in the color memory. The writing material is formed, which can then be dispensed via the writing tip - it is connected to the dye storage. While the rear buffer store only stores the poured solution liquid briefly, especially until the dye store has completely absorbed it, the latter then stores the writing material in liquid form for a very long time.

If a removable cap is provided for the pen, it is advisable to choose the volume of the pen as large as that of the buffer memory. However, since the dye storage is significantly larger than the buffer storage, not only is the production cheaper because of the smaller number of storage units, but the pen thus formed is also provided with a significantly higher writing capacity. A wick is not required since a plurality of individual fiber material stores do not have to be connected.

Writing instruments with the described capillary-writing material storage system can therefore be stored indefinitely, do not dry out during this storage and a user can be sure that when the writing instrument is used for the first time, the full writing capacity - based on the color content in the dye storage - is available.

The last-mentioned dye storage has - according to the in Claim 3 circumscribed invention - an elongated storage body. This is made of fiber material. It is surrounded by a shell that is permeable to liquids and gases and that gives the storage body its shape - and maintains it. The liquid writing material is produced by admixing the dye, which is stored in a dry form between the fibers of the storage body fiber material. A one-part or multi-part wick protrudes from the storage body on both sides.

The success according to the invention is also borne here by the storage of the dye content in dry form. The elongated design of the storage body allows a high storage capacity. The cover gives it dimensional stability and simplifies the manufacture of the writing instruments in which the capillary dye stores are used. Both the high volume as well as the dry storage guarantee the long life initially postulated and allow long-term storage without loss of capacity. The one-part or multi-part wick can also contribute to this, by means of which the solution liquid is supplied on the one hand and via which the solution-enriched with dye - the writing material - on the other hand is removed from the dye storage (claim 4, first alternative). One or more members of the wick is possible due to the capillary flow connection. If the wick is selected in one piece - that is, throughout - the solution liquid absorbs the dye from the storage as it passes through the wick. At the same time, the solution liquid also leaves the wick and arrives in the dye storage in order to be distributed along the fibers there and to emerge again through the wick at the opposite end. In the latter case, the wick can be divided into two, upper and lower partial wick.

Since a flow connection between several stores - individual stores - is not required in the variant according to claim 2, a wick can be omitted there. On the other hand, there is advantageously an enlargement of the dye storage, which at the same time becomes a writing material storage, in particular to double the rear, refillable individual storage (claim 4, second alternative). A further extension of the dye storage / writing material storage is also conceivable, up to a very short rear liquid buffer.

Along its entire extent, the dye storage / writing material storage in the variant according to claim 2 is surrounded by the envelope which keeps it in shape.

The shell can consist of a porous film made of moisture-proof material. If one uses a moisture-proof and low water and gas permeability film - for example polypropylene - this can be perforated, which justifies the porosity (claim 5). The advantage of porosity - due to the gas and moisture permeability or the holes provided for this - is ventilation to the outside when the dye stores are soaked. When refueling, the fiber material core of the dye storage can soak up and swell. For the swelling, the fibers find space in the holes provided in the film which fixes the outer dimension. If the filled-up dye storage is then dried, the evaporating gas of the solution liquid can easily escape through / through the porous film. The color pigments thus remain in the dye storage. Due to the porosity, almost complete drying of the dye storage is guaranteed. The dry ink depot (the dye storage) receives its high capacity of dye or color pigments.

The capillary wick, which can be inserted into the dye storage, can have rod or knitting needle thickness (claim 6, claim 1). It is stronger than the fiber material of the dye storage surrounded by the shell. Extruded material wicks that are commonly used for fiber tip pens can be used. The capillary wick can be pointed on one or both sides. It can also consist of several parts. However, it is easy to manufacture a continuous wick that penetrates the dye storage over its entire length. A small part of the long capillary wick then protrudes from both end faces of the elongated dye reservoir. The protruding sections form the connection to the further stores arranged on both sides of the dye store (cf. claim 1).

Finally, a method (claim 7) for producing the described capillary dye store (claim 3) is essential both for the storage system according to claim 1 and for the storage system according to claim 2.

According to the four main process steps, an elongated capillary fiber body is covered with a gas and liquid permeable film. But it is liquid-proof. The fiber body thus coated is impregnated with a color concentrate, which is done by inserting the fiber body into the concentrate or by introducing the concentrate into the fiber body. Then the impregnated fiber body is drained and dried. The one-part or multi-part rod-shaped wick that can be inserted into the fiber body (cf. claim 1, not claim 2) has a length that is greater than the longitudinal dimension of the fiber body (claim 8). The wick can be introduced into the fiber body after drying, but it can also be done after dripping - before drying - or it can be done before soaking.

If the dye stores are produced in accordance with the described method, then they receive the required high storage capacity of dye while at the same time being inexpensive to manufacture in large series. During the process steps described, they can be stored in wire baskets, the containers being able to have a high capacity - that is to say containing a multiplicity of color depots.

Repeated soaking increases the concentration of the dye in the dye store (claim 9). It is advantageous to use a concentrated color solution, made from color pigments and a solvent, for example based on water or alcohol (claim 10). Other solvents can also be used. The greater the degree of dryness of the dry dye storage, the higher the color concentration and the more favorable the long-term storage conditions.

Therefore, a two-stage drying process can be provided (claim 11, 12). According to this, the drained dye stores are first dried in the air, in order to then be subsequently or finally dried in an oven. The oven can be dried under vacuum conditions, which accelerates the expulsion of all solvents.

Figur 1

zeigt schematisch einen Schnitt durch ein Schreibgerät mit drei Einzelspeichern 10,20,30.

Figur 2

zeigt - perspektivisch - die Hintereinander-Anordnung der drei Einzelspeicher 10,20,30, wobei der mittlere Einzelspeicher 20 - der Farbstofftrockenspeicher - hervorgehoben ist.

Figur 3

zeigt einen horizontalen Schnitt durch den erwähnten mittleren Farbstoffspeicher 20, in dem der Docht 1 ersichtlich ist.

Figur 4

zeigt einen Marker, der nur einen (vergrößerten) Farbstoffspeicher 20a aufweist

Die Figur 1 bildet - im Schnitt - einen Faserschreiber ab. Am unteren Ende des Faserschreibers 100 ist eine Spitze 3 vorgesehen, die aus extrudiertem Material gefertigt sein kann. Am oberen Ende ist eine abschraubbare oder abnehmbare Kappe 2 angeordnet, über die dem darunterliegenden ersten Einzelspeicher 10 Lösungsflüssigkeit zugeführt werden kann. Darunter liegt der zentrale Farbstoffspeicher 20, der den Farbstoff in trockener Form speichert. An ihn schließt sich der Einzelspeicher 30 für den fertigen Schreibstoff an, in ihn ragt von der Spitze des Schreibgerätes 100 her die Schreibspitze 3 hinein.Comprehension of the invention is studied on examples of execution.

Figure 1

shows schematically a section through a writing instrument with three individual memories 10, 20, 30.

Figure 2

shows - in perspective - the consecutive arrangement of the three individual stores 10, 20, 30, with the central individual store 20 - the dry dye store - being highlighted.

Figure 3

shows a horizontal section through the above-mentioned middle dye store 20, in which the wick 1 can be seen.

Figure 4

shows a marker which has only one (enlarged) dye store 20a

Figure 1 shows - on average - a fiber pen. At the lower end of the fiber pen 100, a tip 3 is provided, which can be made of extruded material. A screwable or removable cap 2 is arranged at the upper end, via which solution liquid can be supplied to the first individual store 10 below. Below this is the central dye storage 20, which stores the dye in a dry form. It is followed by the individual memory 30 for the finished writing material, and the writing tip 3 projects into it from the tip of the writing instrument 100.

The three individual memories 10, 20, 30 arranged one behind the other are stored in a housing 4, which forms the casing of the writing instrument 100. The three individual stores mentioned are connected to one another in the longitudinal direction by a wick 1. It can be located centrally and in the central axis of the three stores, but it can also go diagonally through the dye store 20 and accordingly open into the individual stores 10, 30 arranged on both sides.

Depending on the shape of the writing instrument 100, the jacket 4 is round, square or triangular in shape. The individual memories 10, 20, 30 also adapt to this jacket shape, which can then also be round, square or triangular.

In any case, the round design is advantageous, so that all three individual stores 10, 20, 30 have a cylindrical shape. With regard to the length of the individual memories, different precautions can be taken depending on the writing capacity and the chosen dye. If a high color capacity is required, the central color memory 20 takes precedence and takes up a high percentage of the existing interior of the jacket 4. The storage for the liquid in the liquid store 10 is less critical. It can be refilled as desired and thus does not have to have a high capacity. The capacity of the writing material store 30 can also be low, since it is continuously supplied from the dye storage device 20 and the liquid storage device 10 above it

For the structure of the individual memories, reference is made here only to the fiber materials of the dye memory 20, which are designated by 21. The filling can be any type of fiber material, cellulose acetate or polyester is advantageously used.

FIG. 2 deepens the illustration according to FIG. 1 by drawing out a perspective design of the possible cylindrical individual memories. All three stores 10, 20, 30 are connected to each other via the wick 1. Originally, the wick 1 was initially only inserted through the ink reservoir 20, so that 20 ends of the wick 1 protrude on both ends of the dye reservoir. These ends are then pushed into the other stores 10, 30. There is thus a capillary flow connection from the memory 10 to the writing material storage 30, at the end of which the fiber tip 3 discussed releases the writing material onto the paper of the user.

The fiber material 21 and 31 fills the memory 20 and 30, the same also applies to the filling of the memory 10. The dye storage 20 is to be emphasized. It has a casing 22 - which is also shown in section in FIG. 3 - with which it retains its shape. A multiplicity of openings 23 are made in the casing, which allow liquid to get into the fibrous filling of the reservoir 20 - thus when the reservoir is soaked. At the same time, the perforation 23 of the sheath 22 allows fibers of the fiber material to escape during the impregnation - due to swelling. It then takes on a shape as shown schematically in FIG. 3, where fibers emerge from the holes 23 due to the swelling of the filling, but are simultaneously held as tufts in the openings. If the ink depot 20 is then dried - after soaking and draining - the holes 23 form an excellent, even outlet for the resulting gases of the solvent with which the color pigments entered the dye store.

The only prerequisite for the sleeve 22 is that it is liquid-tight, so it must be resistant. In terms of durability, however, it should have a porosity that serves the functions mentioned. On the one hand, porosity means that openings are provided if the film used for the cover 22 is gas and / or water impermeable. Porous also means that a gas- and water-permeable film can be used. Likewise, a combination can be selected from gas and moisture-permeable film, into which additional openings 23 be introduced.

The arrangement of the holes 23 can be symmetrical, but it is not absolutely necessary, and an arbitrary distribution on the surface of the storage body 20 is also possible.

Figure 3 has already been mentioned. A section through the storage body 20 is shown in it. The wick 1 lies centrally in the fiber material 21, which forms the heart of the dye storage 20. The emerging tufts of fiber material from the openings 23 were the result of the intensive impregnation process, the exited tufts of fibers no longer completely returning to the cylindrical shape of the dye storage 22 after drying.

With regard to the wick 1, it should be noted that although this is shown as a continuous wick 1, an interrupted design can also be selected. Two parts of the wick are pushed into the color depot 20 on both end faces in order to create a connection to the adjacent stores 10.30. An internal connection running in the reservoir 20 is not absolutely necessary, because the fiber material also has a capillary action and directs the solution liquid from the individual reservoir 10 - enriched with color pigments - to the writing material reservoir 30 via the lower part of the wick.

A method with which the dye cartridge 20 can be produced is to be described, without drawings. The starting point is a concentrated color solution that is produced on a water or alcohol basis. The solvents should be able to evaporate easily, which is why water or ethanol are particularly suitable. At the same time, however, they should have sufficient solubility to bind at least 10% of the dyes in the solution.

A suitable fiber for the cartridge 20 is cellulose acetate or polyester, but other fiber materials can also be used. The cellulose acetate or polyester is roughly in Formed and then surrounded by a permeable and / or perforated shell. It allows the solution liquid with the color pigments to enter and allows easy exit with regard to the gas produced during drying.

First, the fibrous cartridges surrounded by the casing are saturated with the above-mentioned color solution. To do this, they are immersed in it. Then they can be removed from the color solution and drained. This can be accelerated under the action of mechanically induced forces.

After draining, the cartridges 20 are basically dried. This drying process can proceed in one or two stages; a two-stage process, in which an air drying process precedes and an oven drying process can follow, has proven particularly useful. Approximately one to two hours are sufficient to essentially complete the air drying. Then comes - depending on performance and temperature - the oven drying process, for which a vacuum oven has proven particularly useful, since this can shorten the time mentioned.

The drying process is followed by a separation process in which the dye stores 20 are shaken in order to separate from one another. The application of this step also depends on how the dye stores 20 have been saturated, drained and dried; if they are stored in baskets which can accommodate a large number of dye stores during the above-mentioned procedures, the shaking process is necessary in order to separate the cartridges from one another. If, on the other hand, soaking, draining and drying are carried out in such a way that the cartridges already go through these process steps individually, the shaking process is no longer necessary.

The production of the dye cartridges 20 is completed in that a wick or rod 1 is inserted lengthwise through the memory 20 and protrudes from both end faces. The wick 1 can be pointed on one or both sides and consist of extruded material, as can the Fiber tip 3 according to FIG. 1. With regard to its strength, it is only important that it must be larger than that of the fiber material 21 held together by the sheath 22, since the wick 1 must penetrate it mechanically.

In Figure 2 , the continuous wick 1 is shown as an example, which can be particularly easily pushed into the cartridge to complete it. With the same effect, however, a two-part rod can also be used, which is inserted into the cartridge 20 on both sides. The connection between the ends located in the cartridge then takes place along the fiber material, in which way the solution liquid also absorbs the dyes.

In addition to the porosity of the casing 22 of the dye storage 20, the opening 23 may be present in the film both before the elongated cylindrical shape has been completed, but it can also be subsequently introduced into the cylindrical storage element 20 after a hole-free smooth film has been applied. This can be done in a rolling process between two plates provided with thorns, between which at the same time a plurality of dye stores 20 are provided with openings 23 which are intended to accelerate the impregnation process and at the same time are intended to offer the gas an easy way to escape when the gas dries out.

FIG. 4 shows a marker 110. Its writing tip 3 is thicker than the writing tip 3 of the pen according to FIG. 1, which can be a liner or a fiber pen. It also has the jacket 4, which forms the grip sleeve of the pin. While the tip is located at the bottom of the writing end of the cylindrical pen, it is open at the top. This opening can be closed with the cap 2; the cap 2 is shown while it is filling solution liquid into the upper reservoir 40. The liquid introduced collects there temporarily - only briefly - in order to then penetrate into the enlarged dye storage 20a - with cellulose filling 21. There she solves them dry stored color pigments and forms the writing material for the writing tip 3 in liquid form.

This design has special cost advantages, since now only a single writing material / pigment pigment storage is required. The upper liquid reservoir 40 serves to buffer a certain amount of solution liquid predetermined by the cap 2, since this cannot be sucked into the dye reservoir 20a particularly quickly. A plurality of cap fillings can also be used to complete or to refresh the liquid writing material in memory 20a.

The low-cost production was mentioned due to the omission of the wick, the related manufacturing steps and the simplified assembly. However, the possible higher writing capacity should also be mentioned, since a longer color memory 20a can store a larger number of color pigments. Here, the writing material storage 20a can even be selected so large in dry form that the buffer storage 40 for the liquid is only very small. Then liquid must be poured in several times with the cap 2 to form the writing material.

Another advantage is that the writing performance can be refilled (refreshed) in a very metered manner, since only small amounts are added. If, on the other hand, a larger buffer store is used, there is a risk that excessive refreshing will occur and the writing material will be diluted too much.

Claims (12)

1. Capillary writing medium reservoir system for writing instruments (100) such as fiber-tip pens, liners and markers, comprising individual or single reservoirs (10, 20, 30) arranged in the order of the writing medium which contain fibrous material (21, 31, 11) and are in flow communication by a wick (1); where

   (a) the rear individual reservoir (10) is capable of being impregnated from the outside of the writing instrument (100) with a dissolving liquid (5) which it stores;

   (b) the front individual reservoir (30) is in contact with the writing tip (3) of the writing instrument (100) for which it stores writing medium;

   (c) the central individual reservoir (20) stores the color component of the writing medium in dry form.
2. Writing medium reservoir system for writing instruments (100) comprising individual reservoirs arranged one on the other (20a, 40); having

   (a) a rear individual reservoir (40) which can be filled from the outside of the writing instrument (100) with a dissolving fluid (5) which it stores for a limited time

   (b) a front individual reservoir (20a) which stores the color component of the writing medium in dry form and the writing medium in liquid form and which is in contact with the writing tip (3) of the writing instrument (100) for which it stores the liquid writing medium;

   (c) whereby the liquid writing medium is formed in the front individual reservoir (20a) when the dissolving fluid (5) filled into the rear individual reservoir (40) enters during the short storage time into the front individual reservoir (20a) and is then stored here for a long time for purposes of writing.
3. Capillary colorant reservoir for writing instruments (100) with a writing tip (3), preferably for fiber-tip pens, liners and markers or for the reservoir systems in Claims 1 or 2 comprising:

   (a) an individual reservoir designed as an elongated reservoir body (20, 20a) which comprises fibrous material (21);

   (b) a shell (22) which is permeable for liquid and gases and which gives the reservoir body (20,20a) its shape;

   (c) colorant for the production of the liquid writing medium which is stored between the fibers (21) of the fibrous material of the reservoir body (20, 20a) in dry form.
4. Colorant reservoir in accordance with Claim 3 in which

   (a) the reservoir body (20) comprises a single-part or multipart wick (1) which protrudes out of it on both sides; or

   (b) the reservoir body (20) is substantially longer - especially about twice as long - as the refillable rear individual reservoir (40).
5. Capillary colorant reservoir in accordance with Claim 3 or 4 in which the shell (22) consists of a porous - especially perforated - film of moistureproof material such as paper, cloth, plastic, metal.
6. Capillary colorant reservoir in accordance with Claim 4 or 5 which

   (a) has a capillary wick (1) with the thickness of a small rod or knitting needle and of greater strength than the jacketed fibrous material, which wick is preferably pointed at both ends;

   (b) is penetrated by the capillary wick (1) over its entire length especially along its axis, said wick (1) extending on both sides out of the end faces of the colorant reservoir (20).
7. Process for the production of a capillary colorant reservoir in accordance with one of Claims 3 to 6 comprising the steps of:

   (a) an elongated capillary fibrous body (20, 20a) is jacketed with a film (22) which is permeable for gas and liquid but liquid-proof;

   (b) the jacketed fibrous body (20, 20a) is impregnated in or with a liquid color concentrate;

   (c) the impregnated fibrous body is drip-dried and then dried.
8. Process in accordance with Claim 7 in which a wick (1) of rod shape and of one or several parts and of a greater length than the elongated fibrous body (20) is inserted into it in its longitudinal direction.
9. Process in accordance with Claim 7 or 8 in which the fibrous body (20, 20a) is saturated by colorant fluid and colorant in the impregnation phase by being immersed once or repeatedly.
10. Process in accordance with one of Claims 7 to 9 in which a concentrated color solution on a water or alcohol base is used for impregnation.
11. Process in accordance with one of Claims 7 to 10 in which the impregnated and drip-dried colorant reservoirs (20, 20a) are dried in two steps.
12. Process in accordance with Claim 11 in which

    (a) the impregnated drip-dried colorant reservoirs (20, 20a) are dried for 1 to 2 hours in air;

    (b) the air-dried colorant reservoirs (20, 20a) are final dried in an oven - especially a vacuum oven.

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