JP2010284918A - Method for cleaning inkjet recording head, and inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To clean an ink discharge-port forming face of a head by efficiently removing an ink-condensed residue adhering thereon. <P>SOLUTION: When an advancing contact angle of ink with the surface of the inkjet recording head is defined as θ<SB>a1</SB>and the advancing contact angle of the ink with the surface of a wiping blade is defined as θ<SB>a2</SB>, the condition of θ<SB>a1</SB>-θ<SB>a2</SB>>13 (degree) is satisfied. At the same time, when an adhesion energy of the ink with the head surface is defined as E<SB>1</SB>and the adhesion energy of the ink with the blade surface is defined as E<SB>2</SB>, the condition of E<SB>1</SB>-E<SB>2</SB>>0.7 (mJ/m<SP>2</SP>) is satisfied. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for cleaning an ink jet recording head (hereinafter also referred to as a recording head or a head) and an ink jet recording apparatus, and the ink concentration attached to a surface (hereinafter also referred to as an ejection surface) on which an ink ejection port of the head is formed. The present invention relates to a technique for efficiently removing and cleaning residues and the like.

  Since the ink jet recording system is a system that converts input image data into an output image through liquid ink, a recording head cleaning (cleaning) technique for ejecting ink is a very important factor. The main problems that require cleaning are briefly described as follows.

  An ink discharge recording head records from a fine nozzle (hereinafter collectively referred to as an ejection port, a liquid path communicating therewith, and an element for generating energy used for ink ejection unless otherwise specified). Ink is directly discharged onto a medium.

  Accordingly, the ejected ink may hit the recording medium and bounce off, or when ink is ejected, fine ink droplets (satellite) may be ejected in addition to the main ink involved in recording and drift in the atmosphere.

  Then, these may become ink mist and adhere around the ink discharge port of the recording head. In addition, dust or the like drifting in the air may adhere. As a result, the attached ink pulls the ejected main ink droplets, thereby changing the ink ejection direction, that is, preventing the straight travel of the main ink droplets.

  Therefore, as a cleaning technique for solving this problem, the inkjet recording apparatus wipes the ejection surface of the head with a wiping member (wiping blade, hereinafter also referred to as a blade) made of an elastic material such as rubber at a predetermined timing. A method called wiping for removing the kimono is employed.

  On the other hand, in recent years, an ink containing a pigment component (pigment-based ink) has been increasingly used as a coloring material for the purpose of improving the recording density, water resistance, light resistance and the like of recorded matter. The pigment-based ink is obtained by dispersing a color material that is originally solid in water by introducing a functional group on the surface of the pigment or the pigment.

  Therefore, the dried pigment ink, which is dried by evaporation of the water in the ink on the ejection surface, causes more damage to the ejection surface than the dry fixed matter of the dye-based ink in which the coloring material itself is dissolved at the molecular level. .

  Moreover, the property that the high molecular compound used in order to disperse | distribute a pigment in a solvent is easy to be adsorb | sucked with respect to a discharge surface is seen. This is a problem that occurs even in cases other than pigment-based inks when a high molecular compound is present in the ink for the purpose of adjusting the viscosity of the ink, improving light resistance, or the like.

  In response to these problems, non-volatile solvent head liquid stored inside the printer body during wiping of the print head is applied to the ejection surface to reduce blade wear and dissolve solid matter accumulated in the print head. The technique which removes the accumulation | storage material by making it do is disclosed (patent document 1 and 2).

  In addition, the contents of performing a wiping operation while ejecting ink droplets from a nozzle of a head and moistening a blade with ink are disclosed (Patent Documents 3 and 4).

  Patent document 5 is mentioned as a prior art example which hydrophilizes a blade member.

Japanese Patent Laid-Open No. 10-138503 JP 2000-203037 A Japanese Patent Laid-Open No. 05-000515 JP 2006-212863 A JP 05-330074 A

  The present inventors verified the long-term cleaning effect by the method disclosed in the above patent document. Then, it discovered that the new problem of the enlargement of the liquid supply member for heads, the ink consumption at the time of ink discharge, and the reattachment of mist arises.

  In Patent Documents 1 and 2, in order to provide a long-term cleaning effect, the head liquid storage member has to be enlarged, which causes a problem of increasing the size and complexity of the printer body. In Patent Documents 3 and 4, since the blade is moistened by ejection, a large amount of ink is consumed in one cleaning. In addition, there is a problem that ink mist is generated at the time of ink discharge, mist adheres after the wiping operation, and the ink discharge direction is changed again.

  Therefore, according to the present invention, by appropriately determining the relationship between the advancing contact angle of the ink and the blade and the ink and the head surface and the adhesion energy, the ink concentration residue can be efficiently and reliably removed from the ejection surface, and the above-described problems are caused. It is another object of the present invention to provide an ink jet recording head cleaning method capable of suppressing the change in the surface characteristics of the ejection surface and maintaining the initial performance of the head.

In order to solve the above-described problems, the present invention provides an inkjet recording head cleaning method in which deposits attached to the surface of an inkjet recording head that ejects ink from nozzles are removed by a wiping blade.
When the advancing contact angle between the ink jet recording head surface and the ink is θ _a1 , and the advancing contact angle between the wiping blade surface and the ink is θ _a2 ,
θ _a1 −θ _a2 > 13 (degree) Equation (1)
Satisfying the above condition, and the adhesion energy of the ink jet recording head surface and the ink is E ₁ , and the adhesion energy of the wiping blade surface and the ink is E ₂ ,
E ₁ −E ₂ > 0.7 (mJ / m ² ) Equation (2)
The condition is used.

Further, the present invention provides an ink jet recording apparatus comprising a means for removing deposits attached to the surface of an ink jet recording head that discharges ink from a nozzle with a wiping blade.
When the advancing contact angle between the ink jet recording head surface and the ink is θ _a1 , and the advancing contact angle between the wiping blade surface and the ink is θ _a2 ,
When the condition of θ _a1 −θ _a2 > 13 (degree) is satisfied, and the adhesion energy between the ink jet recording head surface and the ink is E ₁ , and the adhesion energy between the wiping blade surface and the ink is E ₂ ,
The inkjet recording head, the ink, and the wiping blade satisfying the condition of E ₁ −E ₂ > 0.7 (mJ / m ² ) are used.

  According to the present invention, it is possible to remove the ink concentration residue on the head ejection surface without causing problems such as an increase in the size of the apparatus and generation of mist, thereby maintaining stable image quality.

Explanatory diagram showing the behavior of ink on the ejection surface when wiping with one wiper blade when the relationship between the ejection surface-ink advancing contact angle and the blade-ink advancing contact angle satisfies equation (1) It is. Explanatory diagram showing the behavior of ink on the ejection surface when wiping with one wiper blade when the relationship between the ejection surface-ink advancing contact angle and the blade-ink advancing contact angle satisfies equation (1) It is. When the relationship between the ejection surface-ink advancing contact angle and the blade-ink advancing contact angle does not satisfy the relationship of equation (1), the behavior of the ink on the ejection surface when wiping with one wiper blade is shown. It is explanatory drawing shown. Explanatory drawing which shows the state of the ejection surface after wiping at the time of wiping with one wiper blade when the relationship between the ejection surface-ink advance contact angle and the blade-ink advance contact angle satisfies equation (2) It is. Explanation of the state of the ejection surface after wiping when wiping with one wiper blade when the relationship between the ejection surface-ink advance contact angle and the blade-ink advance contact angle does not satisfy the formula (2) FIG. It is a typical perspective view of the principal part of the inkjet printer which concerns on one Embodiment of this invention. FIG. 6 is a perspective view illustrating a configuration example of a recording head that can be mounted on a carriage of the ink jet printer of FIG. 5. FIG. 7 is an exploded perspective view illustrating a configuration example of a recording head that is a component of the recording head in FIG. 6. FIG. 8 is a perspective view showing a partially broken structure near a discharge port array for one color in a recording element substrate applied to the recording head of FIG. 7. (A)-(g) is explanatory drawing of the manufacturing process of the recording element board | substrate of FIG. It is a typical side view which shows an example of the cleaning apparatus applied to the printer of FIG. It is a figure explaining the process of wiping.

  The present inventors have made various studies in order to achieve the above object. As a result, when wiping, the ink inside the nozzle is drawn out to the wiper, and the drawn ink is supplied to the discharge surface to dissolve the ink concentration residue on the discharge surface and make it easier to remove from the discharge surface. Found that it is possible to maintain.

  Therefore, further investigations were made with various combinations in which the material, physical properties, etc. of the head ejection surface, blade, and ink were changed. As a result, it has been found that the effects of the present invention are manifested when there is a relationship between the advancing contact angle and adhesion energy between the ink / ejection surface and the advancing contact angle and adhesion energy between the ink / blade.

  Hereinafter, it will be described that the effects of the present invention are manifested by the relationship between the advancing contact angle between the ink / ejection surface and between the ink / blade, and the relationship between the adhesion energy between the ink / ejection surface and between the ink / blade.

  First, the advancing contact angle will be described.

  In the present invention, the advancing contact angle is determined by dynamic contact angle measurement by the sliding method.

  “Dynamic contact angle” is known as a dynamic change in contact angle that assumes a state in which a liquid moves on a solid surface, such as washing and coating (references will be described later). Usually, the contact angle when the droplet interface advances is defined as the advance contact angle θa. In the sliding-down method, a droplet in contact with the sample surface is tilted, and the contact angle of the droplet advancing portion when the droplet slides is defined as the advancing contact angle. In general, it can be said that the smaller the value of the advancing contact angle, the easier it is to wet dynamically.

  The advancing contact angle by the sliding method in the present invention can be measured by, for example, a solid-liquid interface analyzer DropMaster700 (manufactured by Kyowa Interface Chemical Co., Ltd.). Specifically, first, with the solid-liquid interface analysis device, 25 μL of ink jet recording ink is deposited on the test body to form droplets, and the test body is tilted. Then, the slide-down recognition setting is set to 2 dots, and the contact angle of the liquid droplet advancement portion at the time of liquid drop is set as the forward contact angle.

  Next, the adhesion energy will be described.

  The adhesion energy represents the adhesion between the solid surface and the liquid, and is represented by the following formula (3) (reference, Murase Hirahachi, coloring material, 73, [2] 60-66 (2000)).

  In general, it can be said that the larger the value of the adhesion energy, the stronger the adhesion.

  The adhesion energy by the sliding-down method in the present invention can be measured by, for example, a solid-liquid interface analyzer DropMaster 700 (manufactured by Kyowa Interface Chemical Co., Ltd.).

  Specifically, first, with the solid-liquid interface analysis device, 25 μL of ink jet recording ink is deposited on the test body to form droplets, and the test body is tilted. Then, the adhesion energy is a value calculated by using the equation (3) from the measured values of the sliding angle and the landing radius when the droplet falls when the sliding recognition setting is set to 2 dots.

  Next, the relationship between the advancing contact angles between ink / ejection surfaces and between ink / blades will be described.

  FIG. 1 shows the behavior of ink on the ejection surface during wiping when the condition of formula (1) is satisfied. When this condition is satisfied, the wiping blade is more easily wetted than the ejection surface, so that when the wiping blade comes into contact with the ink meniscus of the nozzle, the ink moves to the wiping blade and draws out a large amount of ink existing in the nozzle. Due to this effect, as shown in FIG. 2, the ink concentration residue adhering to the ejection surface of the head contacts the drawn ink.

  On the other hand, when the relationship of the expression (1) is not satisfied, the ink concentration residue cannot be sufficiently dissolved because the effect of drawing out ink from the nozzle by contact with the wiping blade is small as shown in FIG.

In order to draw out an ink amount that can sufficiently dissolve the ink concentration residue, it is more preferable to satisfy the relationship θ _a1 −θ _a2 > 16 °. This is because when the relationship θ _a1 −θ _a2 > 16 ° is satisfied, the amount of ink drawn from the nozzle to the wiper increases, and the ink concentration residue fixed on the ejection surface can be surely dissolved.

  FIG. 4 shows the behavior of ink on the ejection surface after wiping when the condition of Expression (2) is satisfied. In this case, since ink tends to adhere to the ejection surface, the ink tends to remain on the ejection surface even if the wiping blade passes. Therefore, it is possible to sufficiently dissolve the ink concentration residue on the ejection surface.

  On the other hand, when the relationship of the expression (2) is not satisfied, the ink follows the wiping blade as the wiping blade moves as shown in FIG. It cannot be dissolved.

  Even if the condition of the formula (1) is satisfied but the condition of the formula (2) is not satisfied, the ink is pulled out by the contact of the blade, but the ink does not remain on the ejection surface by the movement of the blade, so that the ink concentration residue is dissolved. Less is.

  Further, when the condition of the expression (2) is satisfied but the condition of the expression (1) is not satisfied, the ink concentration effect on the ejection surface is not dissolved because the ink drawing effect by the contact of the blade is small.

  In order to satisfy both of the expressions (1) and (2), the ink concentration residue on the ejection surface can be dissolved by appropriately determining the relationship between the ejection surface of the head, the advancing contact angle of the wiping blade, and the adhesion energy with respect to the ink. A sufficient effect can be obtained.

  That is, the present invention can be realized only by paying attention to the interaction between the ink and the ejection surface and the ink and the wiping blade, and by defining the relationship.

  Next, each embodiment of the apparatus according to the present invention will be described, and the present invention will be described in detail.

(Embodiment of the device)
FIG. 6 is a schematic perspective view of the main part of the ink jet printer according to the embodiment of the present invention.

  In the illustrated ink jet recording apparatus, the carriage 100 is fixed to the endless belt 5 and is movable along the guide shaft 3. The endless belt 5 is wound around a pair of pulleys 503, and a drive shaft of a carriage drive motor (not shown) is connected to one pulley 503. Accordingly, the carriage 100 is reciprocally main-scanned in the left-right direction in the drawing along the guide shaft 3 as the motor rotates. On the carriage 100, a cartridge-type recording head 1 that detachably holds the ink tank 2 is mounted.

  FIG. 7 is a perspective view showing a configuration example of the recording head 1 that can be mounted on the carriage 100 in FIG. 6, and FIG. 8 is an exploded perspective view showing a configuration example of a head unit that is a component of the recording head 1.

  The recording head 1 according to this example includes a head unit 400 having an array of ejection ports that eject ink, and an ink tank 410 that stores ink and supplies ink to the head unit 400. In the recording head 1, the ink ejection port array provided in the head unit 400 faces the paper 6 as a recording medium, and the arrangement direction is different from the main scanning direction (for example, sub-scanning in which the recording medium 6 is transported). Is mounted on the carriage 100 so as to coincide with the direction).

  The number of sets corresponding to the ink color to be used can be provided as a set of the ink discharge port arrays and the ink tanks 410.

  In the illustrated example, six sets are provided corresponding to six colors (for example, black (Bk), cyan (C), magenta (M), yellow (Y), light cyan (PC), and light magenta (PM)). .

  In the recording head 1 shown here, an ink tank 410 independent for each color is prepared, and each is detachable from the head unit 400.

  As shown in FIG. 8, the head unit 400 includes a recording element substrate 420, a first plate 430, an electric wiring substrate 440, a second plate 450, a tank holder 460, and a flow path forming member 470.

A recording element substrate 420 having an ejection port array for each color ink is bonded and fixed on a first plate 430 made of aluminum oxide (Al ₂ O ₃ ), and ink is supplied to the recording element substrate 420 here. An ink supply port 431 for this purpose is formed. Further, a second plate 450 having an opening is bonded and fixed to the first plate 430. The second plate 450 holds the electrical wiring board 440 so that the electrical wiring board 440 for applying an electrical signal for ejecting ink and the recording element board 420 are electrically connected.

  On the other hand, a flow path forming member 470 is ultrasonically welded to a tank holder 460 that holds the ink tank 410 in a detachable manner, thereby forming an ink flow path (not shown) extending from the ink tank 410 to the first plate 430.

  FIG. 9 is a perspective view showing a partially broken structure in the vicinity of the ejection port array for one color in the recording element substrate 420 shown in FIG.

  In FIG. 7, reference numeral 421 denotes a heating element (heater) that generates thermal energy that causes film boiling in the ink in response to energization, as energy used to eject the ink. On the base 423 on which the heater 421 is mounted, a temperature sensor 428 for detecting the temperature of the head unit 400 and a sub-heater (not shown) for keeping the head or ink in accordance with the detected temperature are provided. It is done. Reference numeral 422 denotes an ink discharge port, and 426 denotes an ink flow path wall.

  Reference numeral 425 denotes an ejection port plate in which an ink ejection port 426 is formed in a state of facing each heater, and is disposed on the substrate 423 through a resin coating layer 427. In addition, a desired water repellent material is provided on the surface of the discharge port plate 425 (discharge surface facing the recording medium).

  In this example, two rows of heaters 421 to discharge ports 422 are arranged, and the heaters 421 to discharge ports 422 between the rows are arranged so as to be shifted by a half of the arrangement pitch in the arrangement direction, that is, the sub-scanning direction. Yes. Here, a resolution of 1200 dpi per color ink is realized by arranging 128 heaters 421 to ejection ports 422 per row at a density of 600 dpi. Then, the recording element substrate configuration corresponding to the six colors is arranged on the first plate 430.

  A method for creating the recording element substrate and the ejection surface will be described with reference to FIGS.

  FIGS. 10A and 10B are a schematic perspective view of the recording element substrate 420 and a schematic cross-sectional view taken along the line BB ′, respectively, in which a plurality of heaters 421 are formed on the substrate 1 made of silicon or the like. (Electrodes and the like for energizing the heater are not shown).

  FIG. 10C is a diagram in which the ink flow path pattern forming material 433 is arranged on the base 423 shown in FIG. 10B with a positive resist. The ink flow path pattern forming material 433 includes a common liquid chamber for temporarily holding ink to be supplied to each ejection port, and an ink flow path that branches into a plurality from the common liquid chamber and causes film boiling by the heater. It corresponds to the pattern for composition.

  FIG. 10D shows a nozzle forming material 434 made of a negative resist on the ink flow path pattern forming material 433 shown in FIG. 10C and a water repellent material 435 which is a negative resist containing fluorine and siloxane molecules. It is a figure which shows the state which formed. In the present embodiment, the discharge port plate 425 is formed of these materials.

  By using the water repellent material 435 in this way, it becomes possible to impart water repellency to the ejection surface. Alternatively, in this step, it is possible to change the discharge surface to a desired surface characteristic by changing the material combined with the nozzle forming material.

  FIG. 10E shows a state in which an ink discharge port 422 and an ink path leading to the ink discharge port 422 are formed by a photolithography method with respect to the state of FIG. Further, in FIG. 10F, the ink supply port 424 is formed by anisotropic etching of silicon from the back surface side of the base 423 while appropriately protecting the discharge port forming surface side and the like with respect to the state of FIG. It is a figure which shows the state which carried out.

  FIG. 10G shows a state where the ink flow path pattern forming material 4333 is eluted with respect to the state of FIG. The recording element substrate 420 thus completed is placed on the first plate 430, and further connected to each part, electrically mounted, and the like, thereby obtaining the configuration shown in FIG.

  Referring to FIG. 6 again, the recording medium 6 is intermittently conveyed in a direction orthogonal to the scanning direction of the carriage 100.

  The recording medium 6 is supported by a pair of roller units (not shown) provided on the upstream side and the downstream side in the transport direction, and is transported in a state where a certain tension is applied and flatness with respect to the ink ejection port is ensured. Then, recording on the entire recording medium 6 is performed while alternately repeating recording of a width corresponding to the array width of the ejection ports of the head unit 1 accompanying the movement of the carriage 100 and conveyance of the recording medium 6. The illustrated apparatus is provided with a linear encoder 4 for the purpose of detecting the movement position of the carriage in the main scanning direction.

  The carriage 100 stops at the home position as necessary at the start of recording or during recording. A maintenance mechanism 7 including a cap and a cleaning device described later with reference to FIG. 11 is installed near the home position. The cap is supported so as to be movable up and down, and in the raised position, the ejection surface of the head unit 1 can be capped to protect the head unit 1 during non-recording operation or to perform suction recovery. During the recording operation, the lower position is set to avoid interference with the head unit 1, and preliminary ejection can be received by facing the ejection surface.

  FIG. 11 is a schematic side view showing an example of a cleaning device according to the present invention.

  Wiping blades 9A and 9B made of an elastic member such as rubber are fixed to the wiper holder 10. The wiper holder 10 is in the left-right direction in the figure (the direction perpendicular to the main scanning direction of the recording head 1 and in which the ink discharge ports are arranged). It is movable.

  The wiping blades 9A and 9B have different heights, and when sliding with the ejection surface 11 of the recording head 1, the former is bent relatively large and the side (abdomen) is bent, and the latter is bent relatively small and the tip is bent. The part (edge part) comes into sliding contact. The blade satisfying the provisions of the present invention may be only 9A or both 9A and 9B.

  In the cleaning operation, after setting the recording head 1 to the home position, the wiper holder 10 is moved in the direction of the arrow. In the course of this movement, the relatively long wiping blade 9A first comes into sliding contact with the ejection surface 11, and the relatively short wiping blade 9B follows.

  If the moving speed of the wipe holder 10 is in a practical range, the effect can be exhibited. Specifically, the range of 20 mm / sec to 300 mm / sec is preferable.

  FIG. 12 is an explanatory diagram of this process. The wiping blade 9A is bent relatively large, and its side (abdomen) slides on the ejection surface 11, draws ink from the nozzle to the ejection surface, and moves while leaving ink on the ejection surface. In this state, the tip (edge) of the wiping blade 9B abuts on the ejection surface 11, so that the dissolved ink residue is efficiently scraped and the recording head is cleaned.

  Further, as one means for controlling the blade surface characteristics to satisfy the relational expressions (1) and (2) in the present invention, there is a method of hydrophilizing the member of the wiping blade.

  As a method for forming such a hydrophilic surface, a blade member is coated with a silane compound and adsorbed, or a hydrophilic polymer such as nylon, polyurethane, or polyvinyl alcohol is coated on the blade member and grafted. For example, the rubber surface may be hydrophilized by so-called surface modification, in which the rubber surface is preliminarily plasma-treated, or the polymer is further immersed in the rubber surface to grow a polymer on the surface.

  Patent Document 5 of a conventional example in which a blade member is hydrophilized discloses a recovery method for removing dust, dust, and thickened ink by setting a static contact angle with water to 30 ° or less. However, the relationship between the ink and the ejection surface and the ink and the blade is not described.

  Patent Document 5 discloses a recovery method for removing dust, dust, and thickened ink by setting the static contact angle with water to 30 ° or less. However, the relationship between the ink and the ejection surface and the ink and the blade is not described.

  Furthermore, as a result of verification by the present inventors, merely hydrophilizing the blade unnecessarily draws ink from the nozzle depending on the ink, thereby causing ink contamination around the recovery device and an increase in ink consumption. I understood it. Within the scope of the present invention, a sufficient cleaning effect can be obtained without causing such adverse effects.

Next, an Example and a comparative example are given and this invention is demonstrated concretely. The present invention is not limited by the following examples unless it exceeds the gist. In the text, “part” or “%” is based on mass unless otherwise specified.
Preparation of ink dispersion 1 10 parts of carbon black carbon black having a specific surface area of 220 m ² / g and a DBP oil absorption of 105 mL / 100 g, a styrene-acrylic acid copolymer polymer (acid value 200 mg KOH / g, weight average molecular weight 9, 000, an aqueous solution having a solid content of 20%, 30 parts of a neutralizing agent: potassium hydroxide) and 60 parts of pure water were mixed. Next, this was charged into a batch type vertical sand mill (manufactured by Imex), charged with 200 parts of 0.3 mm diameter zirconia beads, and dispersed for 5 hours while cooling with water. The obtained dispersion was centrifuged to remove coarse particles, and dispersion 1 having a pigment concentration of 10% was obtained.
Preparation of Dispersion 2 To a solution prepared by dissolving 5 g of concentrated hydrochloric acid in 5.5 g of water, 1.5 g of 4-aminophthalic 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. Further, water was added to the self-dispersing carbon black obtained above to prepare a dispersion having a pigment concentration of 10% by mass, whereby Dispersion 2 was obtained.
Preparation of Inks 1 to 7 Using Dispersions 1 and 2, Inks 1 to 7 having the compositions shown in Table 1 below were prepared.

  As a specific preparation method, the following components were mixed, sufficiently stirred, and then subjected to pressure filtration with a micro filter having a pore size of 3 μm (C300A manufactured by Advantech) to prepare an ink. Glycerin and ethylene glycol were used as water-soluble organic solvents, and acetylin E100 (trade name: manufactured by Kawaken Fine Chemical Co., Ltd.) and Zonyl FSO-100 (trade name: manufactured by DuPont) were used as surfactants. ("Acetylenol" is a registered trademark)

Evaluation Head The recording head used for the evaluation was the one mounted on an inkjet printer “PIXUS Pro 9500” manufactured by Canon Inc. ("PIXUS" is a registered trademark)
Wiping blade In this example, a blade having the following physical properties was subjected to hydrophilization treatment with a plasma processing apparatus to form blade A.

Material: Polyether urethane, thickness 0.5mm, width 9mm, hardness 75 °
Further, the blade having the above physical properties not subjected to the hydrophilic treatment was referred to as a blade B.

Measurement of advancing contact angle / adhesion energy Using the ink / wiping blade and the evaluation head prepared by the above method, the advancing contact angle with respect to the ink on the wiping blade, the advancing contact angle with respect to the ink on the head ejection surface, and the ink on the wiping blade Adhesion energy and adhesion energy to the ink on the head ejection surface were measured. The advancing contact angle / adhesion energy was measured using a solid-liquid interface analyzer DropMaster 700 (manufactured by Kyowa Interface Chemical). The results are shown in Table 2. Under an environment of a temperature of 23 ° C. and a humidity of 55%, the droplet contact size was set to 25 μL, the sliding recognition setting was set to 2 dots, and the advancing contact angle and adhesion energy were measured by the sliding method.
Printer Body for Evaluation The printer body used for the evaluation was modified from a recovery system of an inkjet printer “PIXUS Pro 9500” manufactured by Canon Inc. so that the head ejection surface after wiping can be observed.

The inks of Examples 1 to 6 were mounted in the tank position of the recording head of the printer body for evaluation, and the blade A subjected to hydrophilic treatment was mounted on the printer body for evaluation and used for evaluation. The free length and penetration amount of the installed wiping blade were as follows. Here, the free length is the length from the boundary between the wiping blade and the blade support portion to the tip of the blade, and the penetration amount is the height from the position of the ejection surface to the tip of the wiping blade.
Wiping blade A mounting conditions Free length: 5 mm, penetration depth: 1.75 mm (adjusted so that wiper abdomen slides)
Comparative Example As a comparative example, the combination of the ink and the wiping blade in Table 2 was evaluated under the same mounting conditions as in the example. This comparative example does not satisfy both the conditions of the expressions (1) and (2), or the conditions of the expressions (1) and (2).

Evaluation Results Evaluation was performed by observing the head ejection surface before and after wiping at a temperature condition of 25 ° C. Table 3 shows the test results of Examples and Comparative Examples. Evaluation was made in the following three stages.

  AA: A sufficient amount of ink exists around the nozzle, and the ink concentration residue is dissolved.

  A: Ink is present around the nozzle and the ink concentration residue is partially dissolved.

  B: The ink concentration residue around the nozzle remains on the ejection surface without being dissolved.

In Examples 1 to 6 satisfying the expressions (1) and (2), it was confirmed that the ink concentration residue was dissolved. In Examples 2 to 5 satisfying θ _a1 −θ _a2 > 16 ° and Expression (2), it was confirmed that a further sufficient amount of ink concentration residue was dissolved.

  In the combination of the inks of Examples 1 to 6 and Comparative Examples 1 to 8 and the wiping blade, the print image quality after printing on PIXUS Pro 9500 (manufactured by Canon Inc.) and printing 5000 sheets was evaluated. The image quality was better in Examples 1-6 than in 1-8.

DESCRIPTION OF SYMBOLS 1 Inkjet recording head 2 Ink tank 3 Guide shaft 4 Linear encoder 5 Belt 6 Recording medium 9, 9A, 9B Wiper blade 10 Wiper holder 11 Discharge surface 12 Head liquid supply device 14 Head liquid replenishing device 100 Carriage 400 Head unit 410 Ink tank 420 Recording element substrate 421 Heater 422 Discharge port 425 Discharge port plate

Claims (2)

In the inkjet recording head cleaning method of removing deposits attached to the surface of the inkjet recording head that ejects ink from the nozzles with a wiping blade,
When the advancing contact angle between the ink jet recording head surface and the ink is θ _a1 , and the advancing contact angle between the wiping blade surface and the ink is θ _a2 , the condition of θ _a1 −θ _a2 > 13 (degree) is satisfied, and E ₁ the adhesion energy of the ink and the ink jet recording head surface, when the adhesion energy of the ink and the wiping blade surface and E _2, satisfying the condition of _{E 1 -E 2> 0.7 (mJ} / m 2) An ink jet recording head cleaning method. A means for removing deposits adhering to the surface of an inkjet recording head that discharges ink from nozzles with a wiping blade;
When the advancing contact angle between the ink jet recording head surface and the ink is θ _a1 , and the advancing contact angle between the wiping blade surface and the ink is θ _a2 , the condition of θ _a1 −θ _a2 > 13 (degree) is satisfied, and When the adhesion energy between the ink jet recording head surface and the ink is E ₁ and the adhesion energy between the wiping blade surface and the ink is E ₂ , the condition that satisfies E ₁ −E ₂ > 0.7 (mJ / m ² ) is satisfied. An ink jet recording apparatus using an ink jet recording head, the ink, and the wiping blade.

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