JP2007008023A - Waste ink absorber and ink jet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste-ink holding tank and the like which can effectively absorb an ink of high cohesion into a waste ink absorber even if the ink is used. <P>SOLUTION: The waste ink absorber 31d has a hole part 33d in corresponding to the position where the waste ink is introduced. The hole part 33d is made opened to the side of the absorber. The waste ink introduced into the hole part 33d is absorbed with moving in one direction toward the waste ink absorber 31d. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a waste ink absorber that absorbs and holds waste ink (waste liquid) generated by, for example, a recovery operation, and an ink jet recording apparatus including the waste ink absorber.

  Conventionally, in order to improve the quality of recorded images (improved character quality, bleed performance, etc.) for ink jet recording, for example, pigments are used as coloring materials, and inks and ink sets that do not use reaction liquids are used. (See Patent Document 1).

  In addition, in order to keep the ejection operation from the recording head normal, an ink jet recording apparatus having a suction recovery mechanism that forcibly sucks ink from the ejection port is also known. In this type of ink jet recording apparatus, the ink is discharged. The waste ink is absorbed and held by a waste ink absorber.

  On the other hand, with the demand for higher image quality and higher robustness of recording on plain paper, development of inks using pigments that are insoluble in water as color materials is also underway. For example, a two-liquid ink set that uses an ink containing a coloring material and a second ink that reacts with the ink to promote aggregation, or does not use a reactive ink that has been given high cohesiveness immediately after landing of the recording medium. One-pack type ink corresponds to this. In order to obtain high image quality for recording on plain paper, an ink with high cohesiveness of the coloring material on the paper surface is preferable, but this also means that the cohesion of the waste ink is also increased. It is important to efficiently absorb waste ink with high cohesion by an absorber.

As a technique related to the collection of the waste ink, the waste ink absorber provided with a hole (see Patent Document 2), or the pigment ink and the dye ink are dropped in a region close to each other in the waste ink absorber. In this configuration, a mixture of both inks to suppress the generation of aggregates of waste ink has been proposed (see Patent Document 3). In addition, it has also been proposed to provide a hole in a part of the waste ink absorber so that the waste ink absorber can be easily replaced (see Patent Document 4).
JP 2000-198955 A JP 2004-34412 A JP 2002-225313 A Japanese Patent Application Laid-Open No. 6-226995

  There are various forms in which waste ink generated when an image is formed using an ink jet recording apparatus is absorbed by a waste ink absorber. For example, a configuration in which the entire waste ink introduction port directly contacts the waste ink absorber. Various other forms are conceivable, such as a form in which a part of the inlet is in contact with the waste ink absorber, and a form in which the inlet is not in contact with the waste ink absorber.

  The present inventors have studied the shape of the waste ink absorber for the purpose of further improving the absorption performance of the waste ink absorber. As a result, depending on the characteristics of the ink, before the waste ink reaches the entire area of the waste ink absorber, the absorption performance of the waste ink absorber is lost, and as a result, the waste ink may leak from the waste ink absorber. A new problem has occurred. Therefore, the present inventors investigated the relationship between the ink characteristics and the absorption performance of the waste ink absorber to elucidate the cause of the above phenomenon. As a result, it has been found that, in an image formed on a recording medium, the above phenomenon occurs more markedly with an ink having better bleed performance. In particular, a pigment ink containing a pigment as a coloring material and a poor solvent for the pigment as a solvent can significantly improve the bleed performance as compared with conventional pigment inks, on the waste ink absorber, Or, internally, when the water evaporation rate is lower than that of the conventional pigment ink, the dispersion stability of the pigment is lost and it does not re-dissolve, and the waste ink absorption capacity of the waste ink absorber tends to extremely decrease. I understand.

  Thus, as a result of studying a waste ink absorber used for ink having better bleed performance than conventional inks, the conventional techniques have the following problems with respect to absorption of waste liquid. I understood that.

  That is, in Patent Document 2, as shown in FIG. 16, the waste ink absorber 102 in the tank body 111 has a hole portion 106, and a convex portion 113 is formed at the bottom of the hole portion 106. Yes. The waste ink is dripped onto the projection 113, and the dropped waste ink is then absorbed in a scattered manner as indicated by the arrows in FIG. . However, according to the study by the present inventors, it was found that in the case of highly cohesive ink, the waste ink is left on the convex portion 113 in such a configuration in which the waste ink is scattered in this way. Then, it was found that the waste ink left behind is dried to produce aggregates, which become nuclei and grow into aggregates, resulting in overflow of waste ink.

  Further, Patent Document 3 proposes to suppress the formation of aggregates by mixing highly cohesive ink and water-soluble ink such as dye ink. Such an ink with further enhanced cohesiveness may not provide sufficient effects by such a technique, or conversely, depending on the ink, the formation of aggregates may be promoted.

  Japanese Patent Application Laid-Open No. 2004-228561 has a problem of improving the workability of attaching and detaching the waste ink absorber to the housing, and does not have a problem of improving the absorption efficiency in the first place. That is, there is no problem recognition about the correlation between the diffusion due to the waste ink and the waste ink absorber, which the present inventors have focused on.

  Therefore, the present inventors have studied with the object of maintaining the same absorption performance of the waste ink absorber as in the past even when using ink exhibiting excellent bleeding performance on the recording medium as described above. It was.

  The present invention has been made in view of the above-described problems, and the object thereof is to efficiently absorb the ink even when using an ink exhibiting excellent bleeding performance on a recording medium. It is an object of the present invention to provide a waste ink absorber that can be used and an ink jet recording apparatus including the waste ink absorber.

  In order to solve the above problems, a waste ink absorber according to the present invention is used in an ink jet apparatus that forms an image using a liquid that includes a solvent and a coloring material, and the solvent includes a poor solvent for the coloring material. A waste ink absorber that absorbs the derived waste liquid, wherein at least a part of the waste liquid is in contact with the waste ink absorber, and further, the absorption performance of the waste liquid with respect to the ink absorber is different.

  According to the waste ink absorber of the present invention, the waste ink absorber can efficiently absorb the ink even when highly cohesive ink is used.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, the phenomenon that “the absorption performance of the waste liquid with respect to the waste ink absorber is different” will be described in detail.

  FIG. 3 shows a state in which the waste liquid is introduced into the hole, the waste liquid comes into contact with the waste ink absorber, and the waste liquid is absorbed by the waste ink absorber. In such a form, the amount of waste liquid absorbed by the inner peripheral surface A of the hole is larger than the amount of waste liquid absorbed by the inner peripheral surface B or C. This can be explained by the surface energy at the outer periphery of the waste liquid.

  Next, the surface energy at the outer peripheral portion of the waste liquid will be described.

  FIG. 4A is a cross-sectional view of the A-D plane. In FIG. 4A, the surface energy of the waste liquid differs between A in contact with the waste ink absorber and D not in contact with the waste ink absorber. As a result, the movement direction of the waste liquid on the A-D surface acts on the absorber direction.

  On the other hand, FIG. 4B is a cross-sectional view of the B-C plane. In FIG. 4A, since both B and C are in contact with the waste ink absorber, the surface energy of the waste liquid is in an equilibrium state between B and C. As a result, each of the A and D surfaces tries to absorb the waste liquid into the waste ink absorber with the same force.

  As a result, the waste liquid in FIG. 3A has a waste ink absorption capability biased in a certain direction, resulting in the result shown in FIG. 3B.

  As described above, a phenomenon in which the absorbing ability of the waste liquid in a portion in contact with the waste ink absorber is biased is referred to as a phenomenon in which the absorption performance is different in this case.

  As described above, the absorption capacity in a specific direction (direction A in FIG. 3) is different, so that the entire waste liquid existing in the hole portion easily moves to the specific method, and the waste liquid remains in the hole portion. It becomes difficult. For example, the waste liquid level of D in FIG. 3A moves in the direction of the inner surface A as shown in FIG. 3B, and the waste liquid in the hole does not remain.

  On the other hand, in FIG. 9A, the surface energy of the waste liquid on all surfaces is in an equilibrium state. In such a state, the absorption performance of the waste ink absorber is the same. As a result, since the waste liquid is absorbed in the same manner for all the surfaces, as a result, the waste liquid near the center of the waste liquid tends to remain, causing an absorption inhibition factor.

  As described above, as a specific example for realizing a state in which “the absorption performance of the waste liquid with respect to the waste ink absorber is different”, a hole is formed corresponding to the introduction position of the waste liquid, and the inner surface of the hole is further This can be achieved by ensuring that the area in contact with the waste liquid does not equilibrate the surface energy of the waste liquid.

  The above-described form is only a specific example, and is not particularly limited as long as the absorption performance of the waste liquid with respect to the waste ink absorber can be different.

  Further, the “region where the waste ink droplet contacts” refers to at least two portions of the bottom surface, the atmosphere, and the waste ink absorber 31, for example, as shown in regions A and B of FIG. It means the point where and touch.

  As a form to prevent the surface energy of the waste liquid in the area where the waste ink existing in the vicinity of the waste ink introduction portion is in an equilibrium state, a part of the hole formed in the waste ink absorber has a part of the waste ink absorber. For example, an open portion opened on the side surface may be provided.

  Examples of waste ink absorbers having such holes are shown in FIGS. In the waste ink absorber 31a shown in FIG. 2A, the tip of the hole 33a has a semicircular shape. The waste ink absorber 31b shown in FIG. 2B has a hole 33b having a shape in which the root portions of two cuts formed at a distance from each other are connected to each other. In the waste ink absorber 31c shown in FIG. 2C, the width of the hole 33c becomes wider toward the tip. Each of the holes 33a to 33c is not a closed hole, but a part thereof is open to the side surface of the waste ink absorbers 31a to 31c.

  Furthermore, as another form of making the absorption performance of the waste liquid different from that of the waste ink absorber, the waste ink absorber is treated so that the waste liquid has at least two different surface energies. More specific methods include a method of subjecting part of the inner surface of the hole to a hydrophilic treatment or a water repellent treatment. As a method of hydrophilizing or water repelling a part of the inner surface of the hole, a method of hydrophilizing or water repelling the waste ink absorber itself with a part of the inner surface of the hole, or a waste ink absorber A method of forming a part of the inner surface of the hole with another member having a different surface energy may be used.

  An example of the latter case is shown in FIG. The waste ink absorber 31e shown in FIG. 5 is formed with a hole 33e having an open portion in part. And the plate 51 is attached so that the opening part of the hole 33e may be plugged up. The plate 51 is formed of a material such as a resin material and does not absorb ink. The plate 51 may be subjected to water repellent treatment on at least the surface constituting the inner surface of the hole 33e.

  Absorption of the waste ink in the waste ink absorber in this case will be described with reference to FIGS. 6A to 6B and FIG. 7 which is a cross-sectional view taken along the hole in FIG. An example in which the plate 51 is water-repellent will be described.

  FIGS. 6A and 7 show a state immediately after the waste ink 4 is introduced. Thereafter, as time passes, as shown in FIG. 6B, the waste ink 4 moves toward the waste ink absorber 31e, and is finally absorbed without leaving.

  This phenomenon can also be explained by preventing the surface energy of the waste liquid from reaching an equilibrium state as described above. Immediately after the waste ink 4 is introduced, there are a region E in contact with the plate 51 and a region F in contact with the waste ink absorber 31e as the regions in contact with the waste ink 4. Comparing the areas E and F, in the area E, since the waste ink 4 is in contact with the water repellent component, the surface energy is larger than that in the area F. As a result, the waste ink 4 is attracted to the interior of the waste ink absorber 31e having a smaller surface energy, and is moved and absorbed without leaving the waste ink absorber 31e.

  On the other hand, when the hole does not have an open part and the inner surface of the hole is neither hydrophilicized nor water repellent, the behavior of the waste ink is as follows.

FIG. 8 and FIG. 9A show a state immediately after the waste ink 4 is introduced into the hole 2a when the waste ink absorber 2 in which the hole 2a having no open part is formed is used. The inner surface of the hole 2a is not subjected to a hydrophilic treatment or a water repellent treatment. In this state, the periphery of the waste liquid 4 is in contact with the waste ink absorber 2 over the entire circumference. Therefore, the waste liquid 4 has the same surface energy over the entire circumference because the substances in contact therewith are the same over the entire circumference. Therefore, it is estimated that the surface energy of the waste ink 4 is in the vicinity of the center of the waste liquid 4, and as the waste ink 4 is absorbed from the entire outer periphery of the waste liquid 4, as shown in FIG. The waste liquid 4 is left around the center where the surface energy is in an equilibrium state. Thereafter, the remaining waste ink 4 aggregates and becomes a nucleus of the aggregate, which can be an obstacle when the waste ink 4 is absorbed and diffused into the waste ink absorber 2. Therefore, such a hole 2a is not preferable.
However, as shown in FIG. 10, the area of the hole 33f, the discharge speed of the waste ink 4 and the like are controlled so that only a part of the outer periphery of the introduced waste ink 4 comes into contact with the waste ink absorber 31f. Thus, since the surface energy of the waste liquid outer ring portion is partially different, the waste ink 4 is not left in the vicinity of the center as shown in FIG. 9B.

  As described above, in order to efficiently absorb the waste liquid of the ink with improved bleed performance into the waste ink absorber, it is important that the absorption performance of the waste liquid with respect to the waste ink absorber is different. As a result, the waste ink is diffused in the direction of the waste ink absorber and is absorbed by the entire waste ink absorber without leaving any excess.

  The ink with improved bleed performance includes, for example, a self-dispersing pigment (carbon black or the like) in which a hydrophilic group is bonded directly or through another atomic group as a coloring material. As the water-soluble organic solvent, at least one kind uses a water-soluble organic solvent which is a poor solvent having a characteristic of reducing the dispersion stability of the pigment (first ink). When the ink as described above is applied to the recording medium, the ratio of the poor solvent to the pigment increases as the water evaporates, so that the pigments start to aggregate in the upper layer portion of the recording medium. As a result, there is an effect that bleed can be suppressed as a single unit or when there is other ink in the vicinity. Furthermore, as a coloring material of the ink, when a pigment having a high density with respect to the pigment surface of the hydrophilic group to be bonded to the pigment surface is used as the coloring material, the conventional self- The solvent in the ink is less likely to solvate with the pigment as compared with the dispersed pigment, and the dispersion stability of the pigment tends to decrease with a slight water evaporation. As a result, there is an effect of further reducing bleeding. Furthermore, an ink whose viscosity or particle size increases as the water evaporates, more specifically, an ink whose average particle size before and after evaporation changes by 25% or more when water evaporates from the liquid by 40%. Makes it possible to further reduce bleeding. The particle size can be easily confirmed, for example, by measuring the particle size without dilution with a concentrated particle size analyzer FPAR-1000 (trade name; manufactured by Otsuka Electronics Co., Ltd.).

  In the case of the inks described above, if the ink in the ink is not absorbed by the waste ink absorber and the water in the ink evaporates and aggregates are formed or thickened, the recovery operation is repeated to newly evaporate the water. Even if waste ink with a small amount is supplied, it is difficult to re-disperse or reduce the viscosity.

  The degree of evaporation from the waste ink varies depending on, for example, the material of the waste liquid tube or the like, the inner diameter of the tube, and the amount of waste ink discharged in one recovery operation. However, the material of the waste liquid tube and the tube inner diameter that are generally used are limited, and the amount of waste liquid discharged in one recovery operation is generally within a predetermined range.

  There is a clear difference in the absorption performance of the waste ink absorber between the case where the waste ink absorber of the present invention is used and the case where the waste ink absorber of the present invention is not used as the waste ink absorber used in the ink jet recording apparatus on which the above ink is mounted. .

  The poor solvent in the present invention is “a pigment dispersion containing about 50% by mass of the solvent to be determined and containing the coloring material used in the ink in a dispersed state at 48 ° C. for 48 hours. The particle size in the liquid does not contain the solvent to be judged or contains a small amount, and is larger than the particle size of the pigment dispersion containing the water-insoluble colorant used in the ink in a dispersed state. It is a solvent shown. A good solvent is a solvent that exhibits properties other than a poor solvent.

  The waste ink absorber of the present invention is derived from the second ink other than the ink (first ink) containing the solvent and the color material as described above, and the solvent containing the poor solvent for the color material. It is also possible to absorb the waste liquid to be absorbed by the waste ink absorber of the present invention. The introduction position of the waste liquid derived from the second ink with respect to the waste ink absorber is not particularly limited. However, when the waste liquid derived from the liquid containing the solvent and the color material and containing the poor solvent for the color material and the waste liquid derived from the second ink contact on or inside the waste ink absorber, absorption of the waste ink of both liquids When the diffusion or movement into the body is hindered, it is necessary to consider the introduction positions of both waste liquids with respect to the waste ink absorber. More specifically, when each waste liquid is introduced into the waste ink absorber, the solvent contained in the liquid-derived waste liquid containing the solvent and the color material and the solvent containing a poor solvent for the color material, It is necessary to disperse or move alone in the waste ink absorber, and to separate the moved waste liquid and the waste liquid derived from the second ink by a distance as long as possible. More specifically, as shown in FIG. 15, the introduction position 42 of the waste liquid derived from the liquid containing the solvent and the color material, and the solvent containing the poor solvent for the color material, and the waste liquid derived from the second liquid The shortest distance from the introduction position 43 in the waste ink absorber is 5 cm or more and 20 cm or less.

  As an example of the second ink that inhibits the diffusion or movement of both liquids into the waste ink absorber when the first and second inks come into contact with each other, the bleeding on the recording medium is further alleviated. In the case where a solvent which is a poor solvent for the pigment contained in the first ink is contained in the second ink, a benzene ring (as long as a hydrophobic part appears mostly at the end) is used as a coloring material. Ink or the like having at least a color material having a structure having a structure in which a hydrophilic portion may be partly transferred) may be mentioned. Color materials having a structure having a benzene ring at the end generally have a property of being easily adsorbed to a pigment. Accordingly, since the dispersion stability of the pigment is inhibited, when the waste liquid derived from the first and second inks comes into contact with the waste ink absorber, a barrier that inhibits diffusion or movement into the waste ink absorber is provided. Easy to configure. Therefore, the subject in this invention generate | occur | produces notably and the effect made by solving the subject becomes remarkable.

  When the waste liquid derived from the first and second inks comes into contact with the waste ink absorber, a specific example of the second color material that makes it easy to form a barrier that inhibits diffusion or movement into the waste ink absorber is described below. Examples of the coloring material include structural formula (1) and structural formula (2).

(In the structural formula (1), R ₁ represents a hydrogen atom, an alkyl group, a hydroxy lower alkyl group, a cyclohexyl group, a mono- or dialkylaminoalkyl group, or a cyano lower alkyl group, and Y represents a chlorine atom, a hydroxyl group, An amino group, or a mono- or dialkylamino group (which may have a substituent selected from the group consisting of a sulfo group, a carboxyl group, and a hydroxyl group on the alkyl group), R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a carboxyl group (provided that R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are all hydrogen atoms. Except in the case of).)
Specific examples of the compound represented by the structural formula (1) include an exemplified compound having the following structure in the form of a free acid, and an exemplified compound of M7 is particularly preferably used.

(In Structural Formula (2), l = 0-2, m = 1-3, n = 1-3, where l + m + n = 3-4, and the substitution position of the substituent represents the 4 or 4 ′ position. , M represents an alkali metal or ammonium, and R ₁ and R ₂ each independently represents a hydrogen atom, a sulfo group, or a carboxyl group (provided that R ₁ and R ₂ are simultaneously hydrogen atoms). Y represents a chlorine atom, a hydroxyl group, an amino group, or a mono- or dialkylamino group.)
The coloring material represented by the structural formula (2) uses 4-sulfophthalic acid derivative or a phthalocyanine compound obtained by reacting 4-sulfophthalic acid derivative and (anhydrous) phthalic acid derivative in the presence of a metal compound as a raw material. Group is converted to a chlorosulfone group and then reacted with an aminating agent in the presence of an organic amine, that is, the 4 and 4 ′ positions in structural formula (2) (R ₂ in structural formula (2), R ₃ , R ₆ , R ₇ , R ₁₀ , R ₁₁ , R ₁₄ , R ₁₅ ) are introduced to introduce an unsubstituted sulfamoyl group (—SO ₂ NH ₂ ) and a substituted sulfamoyl group (the following structural formula (3)) It has been found that an ink using such a compound as a coloring material has extremely excellent environmental gas resistance.

  Specific examples of the compound represented by the structural formula (3) include an exemplary compound having the following structure in the form of a free acid, and an exemplary compound of C1 is particularly preferably used.

  By using the first ink and the second ink having the above characteristics, the bleed performance can be remarkably improved as compared with the conventional ink. However, when each of the above-mentioned waste inks is dropped on an adjacent portion of the waste ink absorber, a barrier that prevents diffusion or movement into the waste ink absorber is formed, which has not occurred in the past. It has caused a phenomenon.

  In addition, there is a preferable aspect of the present invention in which the first ink is a black ink having a pigment as a color material, and the second ink is a black ink having a dye as a color material. In this case, the black ink having a preferable dye in the color material is the same as that in the case of the color ink, but the color material represented by the following structural formulas (4) and (5) is preferably used as the color material. Is mentioned.

(In Structural Formula (4), R ₁ and R ₂ represent a hydrogen atom, a hydroxyl group, an amino group, a carboxyl group, a sulfo group, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. , R ₃ , and R ₄ are carbon atoms that may be substituted with a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, a hydroxyl group, or an alkoxy group having 1 to 4 carbon atoms. Substituted by an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms which may be substituted with a sulfo group or a carboxyl group, or an alkyl group or an acyl group. And n is 0 or 1).

(In the structural formula (5), R ₅ , R ₆ , R ₇ and R ₈ are a hydrogen atom, a hydroxyl group, an amino group, a carboxyl group, a sulfo group, an alkyl group having 1 to 4 carbon atoms, and an alkyl group having 1 to 4 carbon atoms. An alkoxy group, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, an alkoxy group substituted with a sulfo group or a carboxyl group, an alkoxy group having 1 to 4 carbon atoms that may be further substituted with a carboxyl group or a sulfo group, An amino group substituted by a phenyl group, an alkyl group, or an acyl group, and n is 0 or 1).

  Hereinafter, exemplary compounds Bk1 to Bk3 as specific examples of the dye represented by the structural formula (4) and exemplary compounds Bk4 to Bk6 as specific examples of the dye represented by the structural formula (5) are shown in the form of free acid. The color material used in the invention is not limited to these. Further, two or more kinds of coloring materials listed below may be used at the same time, and those using the exemplified compound Bk3 and the exemplified compound Bk4 at the same time are particularly preferable.

  In the present invention, whether or not the surface energy of the waste liquid is in an equilibrium state is determined by the fact that the ink droplets formed in the holes due to the introduction of the waste ink are not uniformly diffused but diffused in a specific direction. Confirmed by checking.

  As an ink jet recording apparatus according to a second aspect of the present invention, a waste liquid formed by a total waste liquid discharged by a single recovery operation, which is equipped with the waste ink absorber as described above according to the first aspect of the invention. In this case, the surface energy of the waste liquid in the region in contact with is not in an equilibrium state.

  If the waste droplets formed by the waste liquid discharged by one recovery operation do not come into contact with the waste ink absorber, the waste liquid is left unabsorbed until at least the next recovery operation, producing aggregates. And thickening are very likely to occur. Therefore, in order to reliably absorb the discharged waste liquid, it is important that the waste liquid formed by the total waste liquid discharged by one recovery operation surely contacts the waste ink absorber. In addition, by making the surface energy of the waste liquid in the area where the waste droplet contacts come into a state where it does not reach an equilibrium state, the waste ink absorber can efficiently absorb it.

  The recovery operation in the present invention refers to an operation of recovering the ink discharge performance of the recording head by sucking out the fixed ink or the thickened ink inside the ink discharge port of the recording head. Usually, the amount of ink discharged during one recovery operation may vary depending on the non-recording operation time, but the one recovery operation in the present invention is the recovery operation determined by the recording device, It means the case of the minimum ink discharge amount. Therefore, when more ink is discharged, some of the ink droplets formed by the discharged ink come into contact with the waste ink absorber storage portion as waste liquid.

  Further, it is desirable to discharge the waste liquid from the discharge port to the hole by dropping. The dripping in the present invention means that the waste liquid discharged from the discharge port is discharged without contacting the discharge port and the bottom of the hole at the same time.

  When the waste liquid is not dripped, that is, when the discharge port is in direct contact with the waste ink absorber, agglomerates are likely to be generated in the hole, and the discharge port may be blocked, which is not preferable. When the waste ink discharge port and the absorber are in contact with each other, the absorbing portion of the waste ink is concentrated on the absorber, so that it cannot be efficiently absorbed. Further, when waste ink that has not been absorbed generates aggregates, there is a possibility that the discharge port may be immediately closed, which is not preferable.

  The shape of the hole is not particularly limited as long as the surface energy of the ink droplet formed by the ink discharged during one recovery operation is not uniform.

Hereinafter, although it demonstrates more concretely using an Example and a comparative example, this invention is not limited to these, unless the summary is exceeded.
(Used ink)
(Preparation of pigment dispersion for black ink)
To a solution obtained by dissolving 5 g of concentrated hydrochloric acid in 5.5 g of water, 1.5 g of 4-amino-1,2-benzenedicarboxylic acid was added while being cooled to 5 ° C. Next, the container containing the solution was placed in an ice bath and the solution was stirred to keep the solution constantly at 10 ° C. or lower, and 1.8 g of sodium nitrite was dissolved in 9 g of water at 5 ° C. The solution was added. After the solution was further stirred for 15 minutes, 6 g of carbon black having a specific surface area of 220 m ² / g and a DBP oil absorption of 105 mL / 100 g was added with stirring. Thereafter, the mixture was further stirred for 15 minutes. The obtained slurry was filtered with a filter paper (trade name: Standard filter paper No. 2; manufactured by Advantech), and then the particles were sufficiently washed with water and dried in an oven at 110 ° C. to prepare self-dispersing carbon black. Furthermore, water was added to the self-dispersing carbon black obtained above to disperse the pigment concentration to 10% by mass, thereby preparing a dispersion. By the above method, a pigment dispersion was obtained in a state where self-dispersing carbon black having —C ₆ H ₃ — (COONa) ₂ groups introduced on the surface of carbon black particles was dispersed in water.

(Ink composition)
The composition black ink shown below was prepared.
A black comprising 35.0 parts of the above pigment dispersion, 7.0 parts of glycerin, 6.0 parts of diethylene glycol, 0.5 part of diammonium phthalate, acetylenol E100 (manufactured by Kawaken Fine Chemical Co., Ltd.) and 45.3 parts of water is prepared. did.
* 1: Ethylene oxide adduct of acetylene glycol (manufactured by Kawaken Fine Chemical Co., Ltd.)
(Inkjet recording device)
PIXUS550i (trade name: manufactured by Canon) is remodeled as an ink jet recording apparatus so that a rectangular waste ink absorber can be accommodated as shown in FIG. 3, and a tube for introducing the waste ink into the waste ink absorber is provided. A modified machine with a hole at the bottom of the black ink outlet was created. The printer body was mounted with only black ink and evaluated.

Here, the waste ink absorber used was a fibrous body made of pulp.
Example 1
The black ink 1 was used, and the waste ink absorber was shaped as shown in FIG. Printing was performed using the black ink 1, and waste ink derived from each ink was dropped into the hole of FIG.

When the cross section of the hole provided in the waste ink absorber was observed during one recovery operation, a part of the waste ink was in contact with the waste ink absorber.
(Example 2)
The waste ink absorber was shaped as shown in FIG. Printing was performed using the black ink 1, and waste ink derived from each ink was dropped into the hole of FIG.

When the cross section of the hole provided in the waste ink absorber was observed during one recovery operation, the waste ink was in contact with the entire surface of the hole.
(Comparative Example 1)
The black ink 1 was used, and the waste ink absorber had a hole without an opening as shown in FIG.

When the hole provided in the waste ink absorber was observed during one recovery operation, the waste ink was not in contact with the waste ink absorber.
(Comparative Example 2)
The black ink 1 was used, and the waste ink absorber had a hole without an opening as shown in FIG.

When the cross section of the hole provided in the waste ink absorber was observed during one recovery operation, the waste ink was in contact with the entire surface of the hole.
(Evaluation results)
(Evaluation of waste ink absorption performance)
Over several lines, five black and white print patterns with alphabets A to Z are printed on Canon PPC paper, and then suction operation is performed to introduce black ink and color ink into the waste ink absorber. This was continuously performed until 3000 sheets were printed while replacing the ink tank as needed. The results were evaluated according to the following criteria. The results are shown in Table 1.

  ○: The waste ink absorber sufficiently absorbs waste ink and no overflow is observed.

  X: Waste ink cannot be completely absorbed by the waste ink absorber, and overflow is observed.

  Although some embodiments of the present invention have been described above, the present invention may be more specifically as follows.

  As shown in FIG. 12, the ink jet recording apparatus includes a recording head 20 that performs recording by ejecting ink from an ejection port, and a suction recovery mechanism 30 that performs a recovery operation to keep the ejection operation from the recording head normal. And a waste ink storage tank 10 for absorbing and holding waste ink generated by the recovery operation. The recording head 20 and the suction recovery mechanism 30 are general ones used in this type of recording apparatus. The suction recovery mechanism 30 sucks ink with a cap 38 that covers the ejection port surface of the recording head 20. And a discharge pipe 39 for transferring waste ink from the cap 38 to the waste ink storage tank 10.

  As shown in FIG. 13, the waste ink storage tank includes a waste ink absorber 31 and a tank main body 11 that stores the waste ink absorber 31. Where the hole 33 is formed, the bottom surface of the tank main body 11 is partially formed. The exposed ink is dropped toward the bottom.

  The material of the waste ink absorber is not particularly limited as long as it absorbs and holds ink by capillary force, such as a sponge-like porous absorber or a fibrous absorber. In FIG. 13, the waste ink absorber made of a single member is drawn. However, the structure is not limited to this, and a structure in which a plurality of absorbers are stacked may be used.

  According to such a configuration, the waste ink absorption performance in the hole 33 is different between the part facing the absorber and the part facing the wall surface of the tank body 11, and thus the dropped waste ink is Instead of being drawn uniformly in all directions, it is drawn in a specific direction. Therefore, it becomes difficult for the waste ink to remain on the bottom of the hole. Therefore, it is also suppressed that the remaining waste ink is dried and aggregates are generated, and no further growth of the aggregates using the aggregates as nuclei occurs. As a result, it is possible to efficiently absorb waste ink. Further, according to the ink jet recording apparatus of this embodiment provided with such a waste ink storage tank 10, it is highly reliable that leakage from the waste ink storage tank 10 does not easily occur.

  The operation and effect of the present invention as described above is brought about by the fact that the inner surface of the hole is configured to give non-uniform surface energy to the waste ink. Therefore, as long as such a configuration is made, the present invention can be variously modified in addition to the above embodiment.

  That is, the hole may be either a rectangular parallelepiped hole 33 as shown in FIG. 14 (a) or a cylindrical shape as shown in FIG. 6 (b). , 17 may be formed. This is because the non-absorbing area is formed, so that the waste ink is not absorbed in this area, and as a result, the waste ink is not drawn uniformly in all directions. In addition, in the bottom parts 8 and 18 of a hole part, the whole surface becomes a non-absorption area | region which does not absorb waste ink.

  As described above, the “hole” penetrating the front and back of the waste ink absorber has been described as an example. However, in the present invention, instead of the “hole”, the surface of the absorber is dug to a predetermined depth. You may utilize a "concave part". In this case, the bottom of the recess may be a non-absorbing region, and a non-absorbing region (corresponding to the non-absorbing regions 7 and 17 in FIG. 14) may be provided on a part of the inner surface of the recess.

It is the top view and sectional drawing explaining the hole part from which the interfacial energy of the area | region which a waste ink drop contacts becomes non-uniform | heterogenous. It is a top view of the waste ink absorber which shows the various examples of the hole which has an open part. It is a top view of the waste ink absorber explaining absorption of the waste ink in the hole part which has an open part. It is sectional drawing in the hole part vicinity of a waste ink receiving tank explaining the absorption of the waste ink in the hole part which has an opening part. It is a top view of an example of the waste ink absorber comprised so that at least 2 or more types of different surface energy might be provided to the inner surface of a hole. FIG. 6 is a plan view of a waste ink absorber for explaining absorption of waste ink in the configuration shown in FIG. 5. FIG. 6 is a cross-sectional view in the vicinity of a hole of a waste ink receiving tank for explaining absorption of waste ink in the configuration shown in FIG. 5. FIG. 3 is a plan view of a waste ink absorber whose hole does not have an open part and whose inner surface is neither hydrophilized nor water repellent immediately after introducing waste ink into the hole. . It is sectional drawing in the hole part vicinity of a waste ink tank explaining the absorption of the waste ink in the structure shown in FIG. It is a top view of the waste ink absorber which shows the example which made the interface energy of the area | region which a waste ink drop contacts in the hole which does not have an open part non-uniform | heterogenous. It is a top view which shows the kind of waste ink absorber used in the Example. 1 is a schematic diagram illustrating a basic configuration of an ink jet recording apparatus according to an embodiment of the present invention. It is a figure which shows the structure of the waste ink storage tank which concerns on one Embodiment of this invention, Fig.13 (a) is the top view, FIG.2 (b) is a longitudinal cross-sectional view in an AA cut line. It is a figure for demonstrating the relationship between a hole and a non-absorption area | region. It is a perspective view which shows the structure of the waste ink absorber which absorbs two types of waste ink by an example of this invention. It is a figure which shows the structure of the conventional waste ink storage tank.

Explanation of symbols

4 Waste ink 31 Waste ink absorber 33 Hole

Claims (5)

A waste ink absorber that includes a solvent and a color material and is used in an ink jet apparatus that forms an image using a liquid that includes a poor solvent for the color material, and that absorbs a waste liquid derived from the liquid,
A waste ink absorber, wherein at least a part of the waste liquid is in contact with the waste ink absorber, and the absorption performance of the waste liquid with respect to the ink absorber is different.   The waste according to claim 1, wherein a hole is formed corresponding to a position where the waste liquid is introduced, and a region where the waste liquid contacts on an inner surface of the hole does not bring the surface energy of the waste liquid into an equilibrium state. Ink absorber.   The waste ink absorber according to claim 1 or 2, wherein the inner surface of the hole is treated so that the waste liquid has at least two different surface energies.   The waste ink absorber according to claim 2 or 3, wherein the hole has an open portion opened on a side surface of the waste ink absorber.   An ink jet recording apparatus equipped with the waste ink absorber according to claim 1.

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