EP1329323A2 - Ink container with a sponge and process of manufacturing it - Google Patents

Abstract

The method for producing an ink container involves introduction of one or more porous ink absorption elements into a container with at least one ink chamber. The total volume of the elements, being in dry state less than the volume of the container, increases when these elements come into contact with the ink. An Independent claim is also included for a resultant ink container.

Description

The invention relates to a method for producing an ink container with an inserted Sponge, in particular a cartridge for an inkjet printer, and an ink container with inserted sponge.

Ink containers or ink cartridges for inkjet pens or inkjet printers often contain porous ink absorbers for capillary storage of the ink. Sponges, for example made of foamed materials, are preferably used as porous materials Polyurethane, but also fibrous materials, such as felt, and similar materials are used. The porous ink absorbents serve to create a negative pressure in the ink container to produce relative to the ambient pressure and the ink when the To mechanically dampen the ink tank. This also makes sponge ink containers possible with a moving arrangement on the printer carriage a reliable supply of the Printhead with ink. In addition, this is prevented by the capillary forces of the sponge pores created vacuum leakage of the ink into the printer.

In order to optimally fulfill this function, it is necessary that the sponge passes the ink chamber of the container essentially completely and evenly filled and none Has folds or bent corners. Such assembly errors can become undesirable Ink inclusions or air channels and thereby the ink yield of the Sponge ink cartridge and print quality adversely affect.

To these assembly errors, the primary cause of which is the large coefficient of friction between Sponge, or porous material, and wall of the ink container when it is introduced into the ink chamber is to avoid, are complex assembly devices and / or complicated Process steps required. Incidentally, sponge assembly is also made more difficult due to the often complex ink tank geometries, which are based on the design specifications of the printer and to which the sponge geometries must be adapted.

According to the prior art, there are two main methods for sponge assembly applied. According to the first method, the sponge or the porous material is in mechanically compressed in a first process step and in a second process step inserted into the ink chamber of the container. Such a method discloses, for example U.S. 6,250,746. According to the second method, the sponge is in one first process step compressed under the influence of heat, so that it essentially the Has shape of the ink chamber. In a second process step, the so shaped Sponge inserted into the ink chamber of the container. Such a method is for example in EP 0 967 082.

In both known methods there are special tools for mounting the sponge required as well as a precise control of the procedure. Ink Tank Changes and sponge geometries also require expensive tool changes in both cases. After all, the necessary assembly steps increase the cycle times at Ink container manufacturing. The sponge assembly according to the prior art is therefore technical complex and associated with high costs.

The object of the invention is to provide a method by which it is possible to introduce porous material into an ink chamber of an ink container in a simple manner.

According to the invention, this object is achieved by a method according to claim 1. The invention A method of manufacturing an ink tank has the following process steps on: providing an ink container with at least one ink chamber; Provide a porous ink absorbent which has at least one porous body having; Inserting one or more of the porous bodies into the ink chamber (s) of the Container, the total volume of the porous body or bodies in the dry state is smaller than the receiving volume of the respective ink chamber into which the body or bodies is / are used and a porous ink absorbent is selected, the volume of which increases automatically upon contact with a liquid. The ink absorbent is always in the dry state in the assigned ink chamber used. Because it has a smaller volume than the inside of the ink chamber, it can the insertion can be carried out in a simple manner without a special tool.

The porous material is preferably dependent on the shape and size of the ink chamber chosen so that after filling the ink chamber with ink it essentially does so fills out completely and evenly.

An ink tank or cartridge for inkjet pens or inkjet printers usually has one or more ink chambers. In each will be invented one or more bodies made of porous material that contain the ink absorbent form, used, the total volume of the inserted in each ink chamber (s) Body is less than the internal volume of the ink chamber. In particular, the Outer dimensions of the porous ink absorbent consisting of one or more Bodies is formed for each chamber to be smaller than the internal dimensions at the corresponding one Positions of the respective ink chamber.

It is not imperative that each of the outer dimensions of the porous ink absorbent is smaller than the assigned inside dimension of the ink tank. For example a cuboid in a cuboid ink chamber of an ink cartridge Bodies are used, the length and width of which are less than the corresponding Dimensions of the ink chamber, the height of which corresponds to that of the ink chamber. In this case, too, the porous body can enter the ink chamber without friction with the Chamber walls are used.

Subsequent to the introduction of the one or more porous body ink absorbent the ink chamber of the ink container can be closed as usual and to be filled with ink. Contact with the ink causes the porous ink absorbent to swell on. This swelling is a result of part of the ink not going into the Pores of the sponge is stored, but is absorbed by its cell structure.

According to the invention, such materials are selected as the porous ink absorbent, which swell automatically on contact with liquid, i.e. increase their volume. It must the liquid is not necessarily ink. Rather, besides Inks other printing fluids are used, for example those that are used for Print quality improvement serve either before, during or after the application of the Ink can be applied to the print medium in the printer using the porous ink absorbent correspondingly a swellability upon contact with the other hydraulic fluid has to show. It is also possible to swell the ink absorbent Fill the cartridge with a liquid and trigger this before filling with ink vacuum again, d. H. the liquid absorbed by the cell structure remains in the Ink absorbent and this retains its swelling form.

The dimensions of the porous body or the porous bodies in the dry state, i.e. before insertion into the ink chamber are dependent on the swellability of the porous Material and the inner dimensions of the ink chamber preferably to be chosen that the porous body expands to the chamber walls when moistened. On in this way the entire ink chamber is filled with the porous material, so that neither unwanted voids can arise, nor the risk of bending corners of the porous body. Depending on the geometry of the dry ink absorbent however, cavities can also be deliberately created. For example, it is often beneficial keep a distance between the ink-filled sponge and the ventilation openings.

Porous ink absorbents are preferably used, the volume of which is dry Condition that the ink chamber for which they are intended falls below 10% to 60%. The total volume of the porous ink absorbent consisting of one or from a plurality of porous bodies, is thus significantly smaller than the receiving volume the ink chamber for which it is intended. This way it becomes a particularly simple one Introducing allows. Depending on the ability of the porous material to swell, the ratio of the total volume of the porous body or bodies to the volume of the ink chamber, however can also be chosen differently.

According to a particularly preferred embodiment, porous bodies are used whose total volume is the recording volume of the respective ink chamber into which the or the body is / are used to fall below 20% to 50%, in particular 30% to 40%. In the preferred areas mentioned, assembly is quick and easy possible.

As already mentioned, the ratio to be selected in the special application is between the total volume of the porous ink absorbent for each ink chamber and the internal volume of the corresponding chamber depends on various factors. one of these factors is the type of ink with which the appropriate chamber is to be filled. As a general rule it has been found that in the case of oil-based inks, porous bodies are to be selected, the Total volume the receiving volume of the respective ink chamber into which the or Body is / are used to fall below 10% to 20%. For water-based inks the total volume of the porous body is preferably chosen so that it is the volume the corresponding ink chamber falls by about 30% to 60%. As optimal Value related to water-based inks has been found to be approximately 40%.

Preferably, bodies made of porous material are used, the shape of which is essentially corresponds to the shape of the interior of the ink chamber in which the respective body is inserted becomes. In this way, a uniform expansion of the porous material in wet Condition guaranteed in all directions and the isotropic storage property of the used Ink absorbent maintained. This means that the pore volume is above the entire ink chamber is substantially homogeneous, so no ink inclusions or air paths through the porous ink absorbent.

If this is desired, however, one can also be used with the method according to the invention porous material filled ink chamber are produced, in which the mean local pore volume is inconsistent, hence the ink absorbent used is anisotropic Has storage properties. By means of an inhomogeneous distribution of the pore volume can direct the ink in the ink chamber in a certain direction be, for example in the direction of the ink outlet of the container.

Such an inhomogeneous pore distribution can be achieved, for example, with the method according to the invention can be achieved in that the different dimensions of the porous body in the dry state, not all by the same factor, based on the associated dimensions the ink chamber are reduced. With a cuboid sponge, for example, whose length is 0.7 times the length of the ink tank and its width and height that is 0.85 times the width and height of the ink chamber, causes a homogeneous Swelling of the sponge upon ink contact in the ink chamber causes relative sponge compression in the width and height direction, thus an inhomogeneous pore density distribution and consequently anisotropic storage properties of the sponge. An uneven one Pore distribution can also be created by using one of the ink absorbents Ink chamber geometry different shape is selected; z. B. against the ink outlet growing sponge. This measure also has the effect that the body is in different directions to different extents, which in turn leads to the desired Sponge properties.

For example, polyurethane ether foam can be used as the porous material. This Material is particularly suitable if it is the liquid to be absorbed is an oil-based ink. A suitable sponge material is, for example, from Foampartner, Wolfhausen, Switzerland, available under the name "Jet 5". As a general rule Various polyurethane foams are suitable for the process according to the invention, in particular also polyurethane ester foams or a mixture of polyurethane ester and Polyurethane ether foams.

Other porous materials have those used according to the invention for sponge assembly Property of swellability also with water-based inks, so the present Invention advantageous for all common ink systems, in connection with it suitable porous ink absorbents can be used. Since the swelling power of a porous ink absorbent, in addition to its material properties, also essential depends on the liquid or ink to be absorbed, the specific swelling behavior an individual sponge-ink pairing is usually determined using suitable tests become. Based on the specific swelling capacity, the dimensions of the porous Ink absorbent.

A corresponding ink container thus has at least one ink chamber in which a porous ink absorbent is used, the total volume of the or porous bodies that form the ink absorbent is smaller when dry than the receiving volume of the respective ink chamber into which the body or bodies are inserted is / are and whereby the volume of the porous ink absorbent is determined Contact with a liquid increases automatically.

The porous ink absorbent, which has expanded due to contact with a liquid medium, for example ink, essentially touches all of the inner walls of the ink chamber and thus completely fills them. The condition is at least partially reversible, that is, when the ink is completely removed from it, the ink absorbent contracts back to its original size in the dry condition. An ink container according to the invention can thus be recognized by the fact that the porous ink absorbent used in the respective ink chamber has a volume in the dry state that is smaller than the inner volume of the ink chamber in which it is inserted. In particular, all outer dimensions of the porous ink absorbent, which may be composed of a plurality of bodies, may be less than the corresponding inner dimensions of the assigned ink chamber. In _{other words} , for an ink _{container according to the invention,} the volume of the porous ink absorbent in the moist state (V _{pk, moist} ) or in the state of use is greater than the volume of the porous ink absorbent in the dry state (V _{pk, dry} ) or in the assembled state, is: V pk, wet > V pk, dry.

The following table shows a corresponding test result. In the case of a polyurethane ester sponge from Foampartner, Wolfhausen, Switzerland, the outer dimensions and weight of the untreated sponge were first recorded, ie before it was filled with ink; s. Column 2. The corresponding characteristic values of the sponge filled with ink were then determined after a defined exposure time of the ink; s. Column 3. Finally, the ink was squeezed out of the sponge, dried in the oven under defined conditions, and its outer dimensions and weight were again determined. It can be seen that the swelling process is completely reversible. The swollen sponge returns to its original size in the drying process. The fact that the measured thickness of the dried sponge in the present case falls below that of the untreated sponge can be attributed to its residual moisture in the initial state; this confirms the lower sponge weight after the drying process. In the table, the swelling factor denotes the ratio of the different sizes of the damp / ink-filled sponge to the corresponding sizes of the untreated sponge. The reversibility factor indicates the ratio of the sizes of the emptied and dried sponge to the corresponding size of the untreated sponge.

According to preferred embodiments, which can optionally be combined,
porous bodies are used, the total volume of which in the dry state falls below the holding volume of the respective ink chamber into which the body (s) is / are inserted by 10% to 60%;
porous bodies are used, the total volume of which in the dry state falls below the holding volume of the respective ink chamber into which the body (s) is / are inserted by 20% to 50%, in particular by 30% to 40%;
porous bodies are used, the total volume of which in the dry state falls below the holding volume of the respective ink chamber into which the body (s) is / are inserted by 10% to 20%;
porous bodies are used, the total volume of which in the dry state falls below the holding volume of the respective ink chamber into which the body (s) is / are inserted by 30% to 60%;
porous bodies are used, the shape of which essentially corresponds to the shape of the interior of the respective ink chamber into which the body (s) is / are inserted;
porous bodies made of polyurethane ether foam, polyurethane ester foam or a mixture of both are used;
porous bodies are used, the shape of which deviates from the shape of the interior of the respective ink chamber into which the body (s) is / are inserted;
porous bodies are used, the type of which is selected such that even after the swelling, air spaces remain between them and the walls delimiting the ink chamber, including the base part and the ceiling part.

Fig. 1a ein poröses Tintenabsorbierungsmittel zur Verwendung bei der vorliegenden Erfindung;

Fig. 1b ein Gehäuse für eine Tintenpatrone zur Verwendung im Zusammenhang mit der vorliegenden Erfindung in perspektivischer Darstellung;

Fig. 1c eine Ansicht des Gehäuses von Figur 1b mit eingesetztem trockenem Tintenabsorbierungsmittel im Querschnitt;

Fig. 1d eine Seitenansicht des Gehäuses von Figur 1b;

Fig. 2a die Seitenfläche eines weiteren porösen Tintenabsorbierungsmittels zur Verwendung im Zusammenhang mit der vorliegenden Erfindung im trockenen und im nassen Zustand;

Fig. 2b das Tintenabsorbierungsmittel von Fig. 2a in Dickenansicht;

Fig. 2c das Tintenabsorbierungsmittel von Fig. 2a im trockenen Zustand (Ausgangszustand) sowie nach dem Quellen in Tinte und anschließendem Trocknen.

The invention is explained below with reference to the accompanying drawings. The drawing shows:

Figure 1a shows a porous ink absorbent for use in the present invention;

1b shows a housing for an ink cartridge for use in connection with the present invention in a perspective view;

1c is a cross-sectional view of the housing of FIG. 1b with the dry ink absorbent inserted;

1d shows a side view of the housing from FIG. 1b;

Figure 2a shows the side surface of another porous ink absorbent for use with the present invention in the dry and wet states;

Fig. 2b shows the ink absorbent of Fig. 2a in a thickness view;

Fig. 2c, the ink absorbent of Fig. 2a in the dry state (initial state) and after swelling in ink and subsequent drying.

In Figure 1a is a perspective view of a porous ink absorbent 1, the here is formed by a single body with flat side walls 1a shown. In a alternative embodiment, the ink absorbent 1 can also be composed of several Bodies exist. The ink absorbent has a given total volume v on, as well as a length 1 (here variable over the width), a (here over the length variable) width b and a uniform height h here.

The ink absorbent 1 shown is intended to be used in the method according to the invention in the housing 2 shown in Figures 1b to 1d, more precisely expressed in it Ink chamber 3 to be used. The housing 2 includes in addition to the ink chamber 3 usual elements, such as an ink outlet opening 4. These other elements are known to the person skilled in the art and should therefore not be explained in more detail here.

In the case shown, the ink chamber 3 has a different shape than the associated ink absorbent 1. In an alternative embodiment, the shape of the interior of the Ink chamber 3, however, the shape of the porous ink absorbent substantially correspond. The ink chamber here has a uniform length L, a uniform width B and a uniform height H and a total volume V. Essential to the invention it is now that when the porous ink absorbent is dry Total volume v is smaller than the total volume V of the ink chamber 3. At least choose its local length 1 and its local width b smaller than the length L and width B, respectively the corresponding position (in terms of width and height or in terms of length and height) of Ink chamber. The height h of the porous ink absorbent is also preferred less than the height H of the ink chamber. This condition is best seen in the cross-sectional view can be seen from Figure 1c.

If the ink container is now filled with a liquid, for example ink, expands the porous ink absorbent swells on all sides due to its swellability out and thus increases its volume. In the described embodiment, that is sufficient However, swelling does not occur at the point of bevel 5 of the porous ink absorbent through this and the adjacent chamber wall with the ventilation opening 6 to fill the specified cavity or air space. So this changes the ink absorbent by swelling in such a way that it remains thereon Air space on the wall of the ink chamber, d. H. including the the chamber delimiting cover.

Another embodiment of a porous ink absorbent is shown in Figs. 2a and 2b 1, each in the dry state (initial state when inserting the Ink absorbent in the ink chamber) and in the swollen or moist state. A uniform expansion can be seen in all directions. The expansion is in the case where the porous ink absorbent is set in the ink chamber, obstructed by the walls of the ink chamber, d. H. the sponge becomes swollen compressed. If the geometric shape of the ink chamber from that of the porous Ink absorbent is different, anisotropic compression of the ink absorbent takes place, d. that is, there is an inhomogeneous pore density distribution. Such For example, it may be desirable to adjust the ink flow in a preferred direction direct the acting capillary forces. A complete removal of the ink the porous ink absorbent causes it to contract until its initial state is essentially reached again.

2c shows the ink absorbent shown in FIGS. 2a and 2b, on the left side of this figure in the dry state (initial state) and on the right side of this figure in a state of swelling in ink and then drying. It can be seen that both states essentially are identical, i.e. the volume change of the porous ink absorbent 1 is essentially completely reversible with a constant shape.

Claims (18)

A method of manufacturing an ink tank, comprising the following steps: Providing an ink container with at least one ink chamber (3); Providing a porous ink absorbent (1) having at least one porous body; Inserting one or more of the porous bodies into the ink chamber (s) of the container, characterized in that the total volume of the porous body or bodies in the dry state is smaller than the receiving volume of the respective ink chamber (3) into which the body or bodies is / are inserted and in that a porous ink absorbing agent is selected, the volume of which changes due to contact automatically enlarged with a liquid. A method according to claim 1, characterized in that porous bodies are used, the total volume of which in the dry state falls below the holding volume of the respective ink chamber into which the body or bodies are / are used by 10% to 60%. Method according to claim 1 or 2, characterized in that porous bodies are used, the shape of which essentially corresponds to the shape of the interior of the respective ink chamber into which the body or bodies are / are inserted. Method according to one of claims 1 to 3, characterized in that porous bodies made of polyurethane ether foam are used. Method according to one of claims 1 to 3, characterized in that porous bodies made of polyurethane ester foam are used. Method according to at least one of the preceding claims 1 to 5, characterized in that the ink chamber of the ink container is then filled with ink and sealed. Method according to at least one of claims 1 to 6, characterized in that porous bodies are used, the total volume of which, in the dry state, the receiving volume of the respective ink chamber into which the body or bodies is / are used, in particular by 20% to 50% Falls below 30% to 40%. Method according to at least one of claims 1 to 7, characterized in that porous bodies are used, the total volume of which in the dry state falls below the holding volume of the respective ink chamber into which the body or bodies are / are used by 10% to 20%. Method according to at least one of claims 1 to 7, characterized in that porous bodies are used, the total volume of which in the dry state falls below the receiving volume of the respective ink chamber into which the body or bodies are / are used by 30% to 60%. Ink container, in particular produced by a method according to claims 1 to 9, comprising at least one ink chamber (3), in which a porous ink absorbent (1) is inserted, characterized in that the total volume of the porous body or bodies which contain the ink absorbent (3 ) in the dry state is smaller than the receiving volume of the respective ink chamber (3) into which the body (s) is / are inserted and that the volume of the porous ink absorbing agent (1) increases automatically due to contact with a liquid. Ink container according to claim 10, characterized in that porous bodies are used, the total volume of which in the dry state falls below the receiving volume of the respective ink chamber into which the body (s) is / are 10% to 60%. Ink container according to claim 11, characterized in that porous bodies are used, the total volume of which, in the dry state, the receiving volume of the respective ink chamber into which the body (s) is / are inserted by 20% to 50%, in particular by 30% to 40 % falls below. Ink container according to claim 11, characterized in that porous bodies are used, the total volume of which in the dry state falls below the receiving volume of the respective ink chamber into which the body or bodies is / are 10% to 20%. Ink container according to claim 11, characterized in that porous bodies are used, the total volume of which in the dry state falls below the receiving volume of the respective ink chamber into which the body or bodies is / are 30% to 60%. Ink container according to at least one of the preceding claims 10 to 14, characterized in that porous bodies are used, the shape of which essentially corresponds to the shape of the interior of the respective ink chamber into which the body or bodies is / are inserted. Ink container according to at least one of the preceding claims 10 to 14, characterized in that porous bodies are used, the shape of which deviates from the shape of the interior of the respective ink chamber into which the body or bodies is / are inserted. Ink container according to at least one of the preceding claims 10 to 16, characterized in that porous bodies are used, the shape of which is selected such that even after swelling, air spaces remain between them and the walls delimiting the ink chamber, including the base part and cover part. Ink container according to at least one of the preceding claims 10 to 17, characterized in that porous bodies made of polyurethane ether foam, polyurethane ester foam or a mixture of both are used.

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