JP6337988B2 - Ink absorber and inkjet printer - Google Patents

Description

The present invention relates to an ink absorber and an ink jet printer including the ink absorber .

  Conventionally, for example, an absorbent body mainly composed of cellulose fibers is known as a liquid absorbent body that absorbs ink (see, for example, Patent Document 1).

JP 2000-135797 A

  In Patent Document 1, since the above-described penetrability of penetrating the ink to the absorber is not satisfied, a bulky synthetic fiber sheet layer is laminated on at least one surface of a base material layer mainly composed of cellulose fibers to achieve the penetrability. Secured. However, in Patent Document 1, since the permeability in the base material layer has not changed, the problem that the ink does not permeate the entire base material layer has not been solved.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 The liquid absorber according to this application example is a liquid absorber that absorbs liquid, and the liquid absorber mainly includes fibers and has a critical surface tension higher than the critical surface tension of the fibers. It contains large additives.

  According to this configuration, the liquid absorber mainly includes fibers and further includes an additive having a critical surface tension larger than the critical surface tension of the fibers. Thereby, an additive will exist between fibers and the part will become wet easily with respect to a liquid, and can improve the permeability of a liquid as a whole. In addition, the retention of the liquid absorbed by the action of the additive can be enhanced.

  Application Example 2 The additive of the liquid absorber according to the application example is characterized in that the critical surface tension is larger than the surface tension of the liquid.

  According to this configuration, by applying an additive having a critical surface tension larger than the surface tension of the liquid, it becomes easier to get wet with the liquid, and the permeability of the liquid can be enhanced.

  Application Example 3 In the liquid absorber according to the application example described above, the critical surface tension of the additive is 1.5 times or more the critical surface tension of the cellulose fiber.

  According to this configuration, the permeability can be further improved.

  Application Example 4 A liquid absorption tank according to this application example includes the liquid absorber described above and a storage unit that stores the liquid absorber.

  According to this configuration, by storing a liquid absorber having liquid permeability and retention, for example, even when the liquid absorption tank is disposed obliquely or horizontally, the absorbed liquid is retained, Leakage etc. can be prevented.

  Application Example 5 An electronic apparatus according to this application example includes a discharge unit that discharges the liquid and the liquid absorption tank that captures the discharged liquid.

  According to this configuration, it is possible to provide a highly reliable electronic device that efficiently absorbs liquid and does not cause defects such as liquid leakage. In addition, as an electronic device, it can apply to the electronic device using various liquids, such as an inkjet printer provided with the head which ejects the ink as a liquid, for example.

The schematic diagram which shows the structure of a liquid absorber. Schematic which shows the structure of a liquid absorption tank. Schematic which shows the structure of an electronic device. The schematic diagram which shows the evaluation method of the ink permeability of a liquid absorber, and ink retention.

[Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the scale of each member or the like is shown differently from the actual scale so as to make each member or the like recognizable.

  First, the configuration of the liquid absorber will be described. FIG. 1 is a schematic diagram showing the configuration of the liquid absorber. A cuboid liquid absorber 200 shown in FIG. 1 absorbs liquid and is mainly composed of cellulose fibers as fibers. In addition to the cellulose fiber, the liquid absorbent 200 according to the present embodiment includes a molten resin, a flame retardant, and an additive having a critical surface tension larger than the critical surface tension of the cellulose fiber.

For example, the cellulose fiber of the present embodiment is obtained by defibrating a bleached pulp sheet using a dry defibrator such as a rotary pulverizer. Therefore, a high purity cellulose fiber is formed.
The molten resin is intended to bond the cellulose fibers and maintain an appropriate strength (hardness, etc.) in the liquid absorber 200, prevent paper powder and fibers from scattering, and contribute to maintaining the shape when absorbing liquid. It is something to do. Various forms, such as fibrous form and powder form, are employable as molten resin. And by heating the mixture which mixed the cellulose fiber and molten resin, a molten resin can be fuse | melted and it can be made to fuse | fuse and solidify to a cellulose fiber. It is desirable to fuse the cellulose fibers and the like at a temperature that does not cause thermal degradation. In addition, the molten resin is preferably in the form of fibers that are easily entangled with the paper fibers in the defibrated material. Furthermore, a core-sheath composite fiber is desirable. The core-sheath-structured molten resin can be firmly bonded by melting the surrounding sheath at a low temperature and bonding the fibrous core to the molten resin itself or cellulose fibers.

  The flame retardant is added to impart flame retardancy in the liquid absorber 200. As the flame retardant, for example, an inorganic material such as aluminum hydroxide or magnesium hydroxide, or a phosphorus organic material (for example, an aromatic phosphate such as triphenyl phosphate) can be used.

As the additive, one having a critical surface tension larger than the critical surface tension of the cellulose fiber is applied. Further, a liquid having a critical surface tension larger than the surface tension of the liquid can be applied. Specifically, any additive having a critical surface tension of 70 to 400 mN / m is applicable. As the additive, for example, calcium carbonate, silica, iron oxide, soda glass and the like can be applied. The additive can be appropriately selected depending on the liquid to be handled. That is, it is preferable to add an additive having a critical surface tension larger than the surface tension of the liquid to be absorbed. For example, when the surface tension of the ink as a liquid is 20 to 40 mN / m and the critical surface tension of the cellulose fiber is 46 mN / m, the difference in the critical surface tension between the ink and the cellulose fiber is small, so that the ink penetration The sex is relatively low. Therefore, an additive that is 1.5 times or more the critical surface tension of the cellulose fiber is applied. In this case, for example, calcium carbonate is suitable. Thereby, the difference in critical surface tension between the ink and the additive (for example, calcium carbonate) present between the cellulose fibers is increased in the positive direction, and the permeability of the ink can be further improved.
In addition to the selection of the additive, for example, when the liquid is dropped on the liquid absorber 200, the contact angle of the droplet with respect to the surface of the liquid absorber 200 becomes almost zero, that is, the liquid is wet. The additive may be selected to have a spreading critical surface tension. In this way, the liquid permeability can be further increased.
The size of the additive may be a size that does not spill from the size that enters between the main cellulose fibers that causes capillary action. Moreover, if it is a size comparable as a cellulose fiber diameter, it is more preferable, without distorting a cellulose fiber.

  As a method for forming the liquid absorbent body 200, for example, a mixture in which high-purity cellulose fibers, molten resin, a flame retardant, and additives are mixed is passed through a sieve, and deposited on a mesh belt disposed below the sieve. Form. And the formed deposit is heat-pressed. As a result, the molten resin is dissolved and formed in a desired thickness. Furthermore, the liquid absorber 200 is formed by die-cutting to a desired dimension.

  The additive is uniformly dispersed in the liquid absorber 200 formed in this way, and the entire liquid absorber can exhibit the permeability without unevenness.

  Next, the configuration of the liquid absorption tank will be described. FIG. 2 is a cross-sectional view showing the configuration of the liquid absorption tank. As shown in FIG. 2, the liquid absorption tank 300 includes a liquid absorber 200 that absorbs liquid and a storage portion 170 that stores the liquid absorber 200.

  The liquid absorbent body 200 is mainly composed of cellulose fibers and contains an additive having a critical surface tension larger than the critical surface tension of the cellulose fibers. The detailed configuration of the liquid absorber 200 is the same as the configuration in FIG.

  The accommodating part 170 which accommodates the liquid absorber 200 is formed in a rectangular shape with a plastic material, for example. The accommodating part 170 includes a bottom part 170a and a side part 170b, and is formed so as to accommodate and hold the liquid absorber 200.

  For example, as illustrated in FIG. 2, when the liquid droplet D is discharged toward the liquid absorber 200 and reaches the surface of the liquid absorber 200, the liquid absorber 200 is more than the droplet D (liquid). Because the critical surface tension is large, it penetrates quickly. And the absorbed liquid is hold | maintained by the effect | action of an additive, etc.

  The liquid absorption tank 300 may have a configuration in which a plurality of liquid absorbers 200 are stacked. Note that the number of stacked liquid absorbers 200 can be set as appropriate. If comprised in this way, the allowance which absorbs a liquid can be increased.

  Next, the configuration of the electronic device will be described. The electronic device includes a discharge unit that discharges the liquid and a liquid absorption tank that captures the discharged liquid. FIG. 3 is a schematic diagram illustrating a configuration of the electronic device. In the present embodiment, the configuration of an inkjet printer as an electronic device will be described. As shown in FIG. 3, the inkjet printer 10 includes a head as a discharge unit that discharges ink as liquid, and a liquid absorption tank that captures the discharged ink (waste ink). In addition, in the inkjet printer 10 of this embodiment, the structure provided with the liquid absorption tank 300 in which said liquid absorber 200 was accommodated is demonstrated.

  The inkjet printer 10 performs carriage 20 that forms ink dots on a print medium 2 such as print paper while reciprocating in the main scanning direction, a drive mechanism 30 that reciprocates the carriage 20, and paper feed of the print medium 2. Platen roller 40, and maintenance mechanism 100 that performs maintenance so that printing can be performed normally. The carriage 20 ejects (discharges) ink mounted on the ink cartridge 26 containing ink, a carriage case 22 in which the ink cartridge 26 is mounted, and a bottom surface side of the carriage case 22 (side facing the print medium 2). A head 24 is provided. The head 24 is formed with a plurality of nozzles for ejecting ink. The ink in the ink cartridge 26 is guided to the head 24, and the ink is ejected from the nozzles to the printing medium 2 by an accurate amount, whereby an image is formed. It is supposed to be printed.

  A drive mechanism 30 that reciprocates the carriage 20 includes a guide rail 38 that extends in the main scanning direction, a timing belt 32 that has a plurality of teeth formed therein, a drive pulley 34 that meshes with the teeth of the timing belt 32, A step motor 36 for driving the drive pulley 34 and the like are included. A part of the timing belt 32 is fixed to the carriage case 22, and the carriage case 22 can be moved along the guide rail 38 by driving the timing belt 32. Further, since the timing belt 32 and the drive pulley 34 are engaged with each other by the tooth profile, when the drive pulley 34 is driven by the step motor 36, the carriage case 22 can be moved with high accuracy according to the drive amount. .

  The platen roller 40 that feeds the print medium 2 is driven by a drive motor or a gear mechanism (not shown) and can feed the print medium 2 by a predetermined amount in the sub-scanning direction.

  Further, the maintenance mechanism 100 is provided in a region called a home position outside the printing region, and the wiper blade 110 that wipes the surface (nozzle surface) on which the ejection nozzle is formed on the bottom surface side of the head 24, and the head 24. A cap unit 120 that is pressed against the nozzle surface and caps the head 24, and a suction pump 150 that discharges the ink as waste ink by driving the head 24 with the cap unit 120 capped. By forcibly discharging the ink from the head 24 by the suction pump 150, it is possible to recover the nozzle that cannot be ejected due to thickening, meniscus destruction, paper dust, etc., or to prevent thickening of the ink in the nozzle. To do. Further, below the suction pump 150, a liquid absorption tank 300 that captures waste ink discharged from the suction pump 150 is provided. By providing the liquid absorption tank 300, the outer shape of the inkjet printer 10 becomes large. By improving the ink permeability and retention of the liquid absorber 200, the volume of the liquid absorber 200 that can hold the same ink amount can be reduced. Thereby, the size of the liquid absorption tank 300 and the inkjet printer 10 is also reduced. The liquid absorption tank 300 has the same configuration as that described in FIG. In addition, the discharged waste ink includes ink that does not reach the medium, such as ink by flushing that ejects ink for the purpose of preventing thickening, and ink that has been removed from the medium in so-called borderless printing. Therefore, it is not always the ink discharged by the suction pump 150. Waste ink refers to ink that has been ejected from the head and has not reached the medium.

  As described above, according to the present embodiment, the following effects can be obtained.

  (1) The liquid absorber 200 contains an additive having a critical surface tension larger than the surface tension of the liquid (for example, ink). For this reason, it will have a larger critical surface tension than the critical surface tension in a cellulose fiber single-piece | unit, and can improve the permeability of a liquid. Furthermore, the liquid absorbed by the additive can be retained. Therefore, it is possible to provide the liquid absorbent body 200 having permeability and holding ability.

  (2) In the liquid absorption tank 300 provided with the liquid absorber 200, even if the liquid absorption tank 300 is disposed obliquely or sideways, the absorbed liquid (for example, ink) is retained and leakage or the like is prevented. Can be prevented.

  (3) In the inkjet printer 10 provided with the liquid absorption tank 300, it is possible to efficiently infiltrate the waste ink discharged from the head 24, prevent occurrence of problems such as ink leakage, and ensure reliability. it can.

[Example]
Next, specific examples according to the present invention will be described.

  1. blend

(1) Cellulose fiber The bleached pulp sheet cut into several centimeters using a cutting machine was defibrated into a cotton shape with a turbo mill (manufactured by Turbo Kogyo Co., Ltd.).

(2) Molten resin A 1.7 dtex molten fiber (Tetron, manufactured by Teijin Ltd.) which has a core-sheath structure, the sheath melts at 100 ° C. or more, and the core is made of polyester.

(3) Flame retardant Aluminum hydroxide B53 (manufactured by Nippon Light Metal Co., Ltd.).

(4) Additives (4-1) Silica: Average particle size 2.6 μm (NIPGEL AZ-200, manufactured by Tosoh Silica Corporation).
(4-2) Silica: Average particle diameter of 6.6 μm (NIPGEL AY-603, manufactured by Tosoh Silica Corporation).
(4-3) Calcium carbonate: Average particle size 2.4 μm (Kallite KT, manufactured by Shiroishi Kogyo).
(4-4) Calcium carbonate: Average particle size 3.1 μm (Callite SA, manufactured by Shiroishi Kogyo).
(4-5) Ground iron oxide: average particle size 4.5 μm
(4-6) Ground soda glass: average particle size 5.0 μm
(4-7) Silica slurry: (AZ-200, manufactured by Tosoh Silica Corporation).
(4-8) Calcium carbonate slurry: (Vakofil 900, manufactured by Shiroishi Calcium Co., Ltd.).
In addition, the average particle diameter of each said additive is the value of D50 measured by Sysmex FPIA2000.

2. Formation of liquid absorber (Example 1: Formation of liquid absorber A)
100 parts by weight of cellulose fiber, 30 parts by weight of molten fiber, 10 parts by weight of flame retardant and 10 parts by weight of additive (4-1) are mixed in the air, and the mixed mixture is passed through a sieve and deposited on a mesh belt. It was. And the deposited deposit was pressure-heat-treated at 200 degreeC. Then, it cut out to 150 mm x 50 mm x 12 mm, and formed the liquid absorber A.

(Example 2: Formation of liquid absorber B)
100 parts by weight of cellulose fiber, 40 parts by weight of molten fiber, 10 parts by weight of flame retardant and 20 parts by weight of additive (4-2) are mixed in the air, and the mixed mixture is passed through a sieve and deposited on a mesh belt. It was. And the deposited deposit was pressure-heat-treated at 200 degreeC. Then, it cut out to 150 mm x 50 mm x 12 mm, and formed the liquid absorber B.

(Example 3: Formation of liquid absorber C)
100 parts by weight of cellulose fiber, 30 parts by weight of molten fiber, 10 parts by weight of flame retardant and 20 parts by weight of additive (4-3 above) are mixed in the air, and the mixed mixture is passed through a sieve and deposited on a mesh belt. It was. And the deposited deposit was pressure-heat-treated at 200 degreeC. Then, it cut out to 150 mm x 50 mm x 12 mm, and formed the liquid absorber C.

(Example 4: Formation of liquid absorber D)
100 parts by weight of cellulose fiber, 40 parts by weight of molten fiber, 10 parts by weight of flame retardant and 20 parts by weight of additive (4-4 above) are mixed in the air, and the mixed mixture is passed through a sieve and deposited on a mesh belt. It was. And the deposited deposit was pressure-heat-treated at 200 degreeC. Then, it cut out to 150 mm x 50 mm x 12 mm, and formed the liquid absorber D.

(Example 5: Formation of liquid absorber E)
100 parts by weight of cellulose fiber, 30 parts by weight of molten fiber, 10 parts by weight of flame retardant and 10 parts by weight of additive (4-5 above) are mixed in the air, and the mixed mixture is passed through a sieve and deposited on a mesh belt. It was. And the deposited deposit was pressure-heat-treated at 200 degreeC. Then, it cut out to 150 mm x 50 mm x 12 mm, and formed the liquid absorber E.

(Example 6: Formation of liquid absorber F)
100 parts by weight of cellulose fiber, 30 parts by weight of molten fiber, 10 parts by weight of a flame retardant and 10 parts by weight of additive (4-6 above) are mixed in the air, and the mixed mixture is passed through a sieve and deposited on a mesh belt. It was. And the deposited deposit was pressure-heat-treated at 200 degreeC. Then, it cut out to 150 mm x 50 mm x 12 mm, and formed the liquid absorber F.

(Example 7: Formation of liquid absorber G)
The additive (4-7 above) was applied to the bleached pulp sheet, and the coated product was dried. Thereafter, the fiber was defibrated with a turbo mill (manufactured by Turbo Kogyo Co., Ltd.) to form a defibrated material containing 100 parts by weight of cellulose fibers and 25 parts by weight of additives (4-7 above). The additive had been pulverized to an average particle size of 5.8 μm (according to electron microscope observation). Then, the defibrated material, 30 parts by weight of molten fiber and 10 parts by weight of a flame retardant were mixed in the air, and the mixed mixture was passed through a sieve and deposited on a mesh belt. And the deposited deposit was pressure-heat-treated at 200 degreeC. Then, it cut out to 150 mm x 50 mm x 12 mm, and formed the liquid absorber G.

(Example 8: Formation of liquid absorber H)
The additive (4-8 above) was applied to the bleached pulp sheet, and the coated product was dried. Thereafter, the fiber was defibrated with a turbo mill (manufactured by Turbo Kogyo Co., Ltd.) to form a defibrated material containing 100 parts by weight of cellulose fibers and 25 parts by weight of additives (4-8 above). The additive was pulverized to an average particle size of 9.9 μm (according to electron microscope observation). Then, the defibrated material, 30 parts by weight of molten fiber and 10 parts by weight of a flame retardant were mixed in the air, and the mixed mixture was passed through a sieve and deposited on a mesh belt. And the deposited deposit was pressure-heat-treated at 200 degreeC. Then, it cut out to 150 mm x 50 mm x 12 mm, and formed the liquid absorber H.

(Comparative Example 1: Formation of liquid absorber R)
100 parts by weight of cellulose fiber, 30 parts by weight of molten fiber and 10 parts by weight of a flame retardant were mixed in the air, and the mixed mixture was passed through a sieve and deposited on a mesh belt. And the deposited deposit was pressure-heat-treated at 200 degreeC. Then, it cut out to 150 mm x 50 mm x 12 mm, and formed the liquid absorber R. That is, the liquid absorber R containing no additive was formed.

3. Evaluation Next, in Examples 1 to 8 and Comparative Example 1 described above, ink permeability, ink retention, and ink deposition were evaluated. Each evaluation method is as follows.

(A) Evaluation Method of Ink Penetration Property and Ink Retention Property FIG. 4 is a schematic diagram illustrating a method for evaluating the ink permeability property and the retention property of the liquid absorber. As shown in FIG. 4A, a liquid absorber T having a size of 150 mm (L) × 50 mm (W) × 12 mm (H) is placed on a flat surface, and ink is formed as a droplet D from the first point P1 on the upper surface. Inject 80 ml slowly. If the absorbent body T does not soak, leave it for 5 minutes and then continue the injection. If the ink does not soak even after being left for 5 minutes, it is considered that the ink does not permeate, and the ink permeability determination is NG. On the other hand, if all of the ink can be injected, the ink permeability determination is OK.
When all the ink has been injected, the ink is left for 5 minutes, and as shown in FIG. 4B, the first point P1 where the ink is injected from the second point P2 using the strap S or the like is downward. Hang like so. In such a suspended state, the permeated ink gathers at one end of the liquid absorber T and is difficult to be held. When the ink drips from the liquid absorber T, it is regarded that the ink cannot be held, and the determination of the ink holding property is NG. On the other hand, if the ink does not drip, the ink retention determination is OK. Note that when the ink permeability is determined to be NG, the desired amount cannot be absorbed, and thus the ink retention is not evaluated. This evaluation shows that ink does not leak even when an electronic device such as an ink jet printer or a liquid absorption tank is inclined.

(B) Method for evaluating ink deposition property A liquid absorber T of 150 mm (L) × 50 mm (W) × 12 mm (H) is placed on a flat surface and placed in an environment of 40 ° C. and 20% RH. Then, 0.4 g of ink is dropped on the center of the upper surface of the liquid absorber T once every hour. Then, after 240 hours, if the thickness of the solid deposit on the surface of the liquid absorber T is less than 1 mm, the determination of the ink depositability is OK. On the other hand, if the thickness of the deposit is 1 mm or more, the ink deposition property is judged as NG.

  In the above examples and comparative examples, ink permeability, ink retention and ink deposition were evaluated. The evaluation results are as shown in Table 1.

  As shown in Table 1, the liquid absorbers A to H (Examples 1 to 8) according to the present invention were excellent for all the evaluations of ink permeability, ink retention, and ink deposition. On the other hand, in Comparative Example 1, a satisfactory result was not obtained. This is because the liquid absorbers A to H according to Examples 1 to 8 contain additives having a critical surface tension larger than the critical surface tension of cellulose and the surface tension of ink. Compared to the liquid absorber R that does not contain (Comparative Example 1), the permeability of the ink is increased, and the retainability is improved. Moreover, since the permeability is high, no deposit remains.

The said Example is employ | adopted as the liquid absorption tank 300 and the liquid absorber 200 used for the inkjet printer 10 as an electronic device. Here, the liquid ink is a variety of liquids such as general water-based ink, oil-based ink, pigment ink, dye ink, solvent-based ink, resin-based ink, sublimation transfer ink, gel ink, hot-melt ink, and ultraviolet curable ink. It is intended to include the composition. Further, the ink may be a material that can be ejected by the head 24. For example, it may be in a state in which the substance is in a liquid phase, such as liquid crystals, liquids with high or low viscosity, sols, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, liquid metals (metals In addition to fluids such as melts) and liquids as a state of matter, functional material particles such as pigments and metal particles dissolved, dispersed or mixed in a solvent, etching liquid Including lubricating oil.
In addition to the ink jet printer 10, for example, an ink containing a material such as an electrode material or a color material used for manufacturing a liquid crystal display, an EL (electroluminescence) display, a surface emitting display, or a color filter in a dispersed or dissolved form. It may be a device for spraying, a device for spraying bio-organic matter used in biochip manufacturing, a device for ejecting ink as a sample used as a precision pipette, a textile printing device, a microdispenser, or the like. Furthermore, a device that injects lubricating oil pinpoint to precision machines such as watches and cameras, a device that forms micro hemispherical lenses (optical lenses) used in optical communication elements, etc. You may employ | adopt the apparatus which injects etching liquid, such as an apparatus to harden | cure, a board | substrate, etc., acid or alkali. The present invention can be applied to any one of these electronic devices.
A liquid that is not discharged as a droplet discharge device may be absorbed. For example, water, oil, sewage, urine, etc. can be said to be generally liquid.

In the above embodiment, a thin non-woven fabric may be attached to the surface in order to prevent fuzz on the surface of the liquid absorber 200. Since the non-woven fabric to be attached is thinner than the liquid absorber 200, there is little influence on the ink permeability and retention.
In the above embodiment, the liquid absorber 200 is a rectangular parallelepiped, but is not limited thereto. A part of the rectangular parallelepiped may have a notch or a recess, and may have an arc portion or an inclined portion instead of the rectangular parallelepiped.

In the above-described embodiments, the pulp sheet includes wood pulp such as conifers and hardwoods, non-wood plant fibers such as hemp, cotton, and kenaf, and waste paper.
In the above-described embodiment, the cellulose fiber is mainly used. However, the material is not limited to the cellulose fiber as long as the material can absorb ink and cause a difference in surface tension from the additive. Fibers made from plastic such as polyurethane and polyethylene terephthalate (PET), and other fibers such as wool may be used.
The method of forming the waste ink absorber is not limited to the method described in the above embodiment. Other manufacturing methods such as a wet method may be used as long as the features of the present application can be obtained.

  DESCRIPTION OF SYMBOLS 10 ... Inkjet printer as electronic equipment, 24 ... Head as discharge part, 100 ... Maintenance mechanism, 170 ... Storage part, 200 ... Liquid absorber, 300 ... Liquid absorption tank.

Claims (2)

An ink absorber mainly composed of cellulose fibers and containing a molten resin and an additive present between the cellulose fibers,
The molten resin is in the form of a fiber with a core-sheath structure, the surrounding sheath is melted, and the core is joined to at least one of the molten resin or the cellulose fiber,
A critical surface tension of the additive is larger than a critical surface tension of the cellulose fiber, larger than a surface tension of the ink to be absorbed, and 1.5 times or more of a critical surface tension of the cellulose fiber. Ink absorber . A head on which ink ejection nozzles are formed;
A pump for discharging the ink from the head;
An ink jet printer comprising: a liquid absorption tank provided with the ink absorber according to claim 1 for absorbing the discharged ink .

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