JP2003191478A - Ink jet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recorder having a high cleaning efficiency whereby nozzle faces of a recording head are less left without being cleaned. <P>SOLUTION: In the ink jet recorder with the recording head and a cleaning mechanism for wiping nozzle faces of the recording head by a blade, a rearward meniscus velocity (RMV) to nozzle faces of ink discharged from nozzles of the recording head, and a velocity (VW) for the blade to wipe nozzle faces hold a relation of VW≤1.1×RMV. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus having a cleaning mechanism for wiping a nozzle surface of a recording head with a wiper blade for recording with a plurality of inks.

[0002]

2. Description of the Related Art While reciprocating a recording head having a plurality of nozzles to the left and right, ink droplets are ejected (discharged) in combination with the movement of a support such as plain paper or special coated paper.
An inkjet recording device configured to form an image (pattern) according to image data on the support is known.

In addition, ink jet recording has a wide range of applications, such as being used for label printing, textile printing (cloth printing), color filter printing for liquid crystal panels, etc. due to the property that the recording medium is not limited.

The ink jet recording apparatus employs a cap means (cap portion) for preventing the ink in the nozzles from drying and a structure for forcibly ejecting the ink from the nozzles as needed. is doing. Further, as a cleaning means for the nozzle surface, a wiping means (cleaning section) using a blade for cleaning the nozzle surface is provided.
Paper waste, dust, or ink adheres to the nozzle surface of the print head, which is located on the carriage that moves along the recording paper, and the ink discharge port is clogged. It prevents the occurrence of failures such as.

In particular, ink (droplets) remaining on the nozzle surface not only causes landing deviation of the ink, but when solidified, it may damage the wiper blade or cause clogging of the nozzle. .

Therefore, wiping (cleaning) of the nozzle surface occupies an important position in order to keep the ink droplets flying normally and to prevent the ink scattering and to maintain a stable operation of the ink jet apparatus.

For this reason, although wiping has been carried out, the ink may be drawn out from the nozzle, paper scraps, dust or thickened ink may adhere to the nozzle surface again. Problems such as clogging of the outlet and defective ejection of ink have not been eliminated, and further improvement is needed.

However, with the diversification of recording media,
The inks used are diverse, and while it is important to perform stable cleaning on various inks,
The wiping residue of the wiping is a static physical property of the ink, even if the viscosity and surface tension are the same, but it is not always possible to uniformly determine the blade wiping speed from these physical property values. To some extent, the method of deciding experimentally was taken. However, depending on the method, there may be a case where a specific ink has a wiping residue or a problem with the correlation with the actual ink, and it is difficult to set a wiping speed with no cleaning residue and good cleaning efficiency for all inks.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink jet recording apparatus which has a small amount of wiping residue on the nozzle surface of a recording head and a high cleaning efficiency.

[0010]

The above objects of the present invention can be achieved by the following means.

1. In an inkjet recording apparatus equipped with a recording head and a cleaning mechanism for wiping the nozzle surface of the recording head with a blade, the receding meniscus velocity (RMV) of ink ejected from the nozzles of the recording head and the blade surface An inkjet recording apparatus, wherein the wiping speed (V _w ) has the following relationship.

V _w ≤1.1 × RMV 2. In an inkjet recording apparatus equipped with a recording head and a cleaning mechanism for wiping the nozzle surface of the recording head with a blade, the receding meniscus velocity (RMV) of ink ejected from the nozzles of the recording head and the blade surface An inkjet recording apparatus, wherein the wiping speed (V _w ) has the following relationship.

0.5 × RMV ≦ V _w ≦ 1.1 × RMV 3. In an inkjet recording apparatus having a plurality of recording heads and a cleaning mechanism for wiping a nozzle surface of the recording heads with a blade, each recording head has a backward meniscus velocity (RMV) of ink ejected from nozzles of the recording head. And the speed (V _w ) at which the blade wipes the nozzle surface of the recording head, the following relationship being established:

0.5 × RMV ≦ V _w ≦ 1.1 × RMV 4. Any one of the above 1 to 3, characterized in that a pigment ink containing a polymer component having a molecular weight of 3000 or more is used.
Inkjet recording apparatus according to the item.

The present invention will be described in detail below. The present invention relates to an inkjet recording apparatus having a cleaning mechanism for wiping a nozzle surface of a recording head with a wiper blade.

A color ink jet recording apparatus is usually
In order to correspond to Y, M, C and K four colors and recent high image quality, dark and light inks may be provided, respectively, and all of these inks are applied to the nozzle surface of the recording head.
When cleaning the ink, it is necessary to prevent the ink from being wiped off.

As a method for cleaning the nozzle surface of the recording head, for example, in the case of using a water-based ink, a method of wiping the nozzle surface of the recording head, which is made water repellent due to its affinity for the water-based ink, is used. .

In the ink jet recording apparatus of the present invention, the backward meniscus speed (RMV) of the ink ejected from the nozzles of the recording head with respect to the nozzle surface and the speed (V _{w at which the} wiper blade wipes the nozzle surface of the recording head). ) Has the following relationship.

V _w ≦ 1.1 × RMV The receding meniscus velocity (RMV) of the ink can be measured by the following method.

(Reverse meniscus velocity (RMV) measurement method)
On the same water repellent surface as the nozzle surface of the recording head, 25 μl of the ink for measuring the receding meniscus velocity was dropped, and as shown in FIG. 1, the distance between the hydrophilic rubber member (6 mmφ) on the lower surface and the water repellent surface was 1 mm. While keeping the ink, the member is rotated at a constant peripheral speed (Vmm / sec) around the rotation axis while holding the ink so as to draw a circle with a radius of 20 mm. Measure the maximum speed at which the ink follows the rubber by changing the peripheral speed. The following speed is the maximum speed at which no ink residue is visually observed on the locus of the rubber.

This receding meniscus velocity changes depending on the ink composition, but unlike static numerical values such as viscosity and surface tension, it is possible to know the dynamic properties of the ink on the nozzle surface. The speed of cleaning the printhead, i.e. wiping by the blade, can be determined individually for each ink.

In the present invention, the wiping speed V _w by the blade is, as described above, the maximum retreating meniscus speed (RMV) of 1.1 relative to the nozzle surface of the recording head having the nozzles for ejecting the ink. By setting the number to be equal to or less than twice, it is possible to eliminate the residue of ink wiping during wiping. Further, if the wiping speed V _w is too slow, control unevenness at a low speed of the drive system such as a motor and mechanical rattling due to gear meshing occur, so that the backward meniscus speed (RM
It is preferably 0.5 times or more of V).

0.5 × RMV ≦ V _w ≦ 1.1 × RMV In this way, by wiping at the wiping speed corresponding to the backward meniscus speed, it is possible to perform cleaning without wiping the ink.

Therefore, in a multicolor ink jet recording apparatus having a plurality of recording heads, the wiping speed (V _w ) by the blade of each recording head nozzle surface is individually set by using the backward meniscus speed (RMV) of the ink used. For example, the wiping speed can be set to be high for a recording head that ejects ink with a high backward meniscus speed, and the wiping speed can be set to be low for a recording head that ejects ink with a relatively low backward meniscus speed. . Normally, in an inkjet recording apparatus, a blade is configured to wipe a plurality of recording heads sequentially at the same speed,
Since there is no choice but to adjust the wiping speed according to the ink with a large amount of ink remaining, it will take extra time,
According to the present invention, the wiping speed needs to be slowed only for the ink having a small RMV, and the fast wiping speed can be applied to the ink having a large RMV. Therefore, the cleaning speed (and therefore the cleaning efficiency) as a whole is increased. It can be shortened.

Further, according to the present invention, when there is a difference in the wiping performance of ink, for example, the wiping speed is set to an excessively high wiping speed for some inks, although some wiping tend to occur. Therefore, there is no difference in wiping performance between the recording heads (inks), and stable cleaning can be performed.

The embodiments of the present invention will be described below with reference to examples.

[0027]

FIG. 2 is a schematic view showing an example of the main constitution of an ink jet recording apparatus of the present invention. The ink jet recording apparatus 1 ejects ink onto a recording paper to perform printing, and as a main configuration of a portion for performing the printing,
As shown in FIG. 2, a conveyance unit (not shown) that conveys the recording paper 2 forward during printing, a recording head 3 that ejects ink onto the recording paper 2, and a carriage that stores the recording heads 3 for each of a plurality of colors. 4, a maintenance unit 5 having a suction cap 16 and a blade 17 for performing maintenance of the recording head 3, and a guide rail 6 for guiding the carriage 4 along the horizontal direction (arrow A) during printing or maintenance. A home position 7 having a moisturizing cap 8 serving as a waiting place for the carriage 4 and a control unit (not shown) for controlling these units are provided. C is an ink cartridge, and each ink sent from the ink cartridge C is temporarily stored in the sub-tank T, and then sent to the recording head through the supply valve V and the ink supply path P.

The recording sheet conveying means conveys the recording sheet 2 on the printing area 9 at the timing of the operation of the carriage 4 during printing, and when the printing is completed, the recording sheet 2 is conveyed.
Is conveyed downward from the print area (arrow B).

FIG. 3 is a schematic view showing the structure of the recording head. The recording head 3 includes an ink ejection main body 11 for ejecting ink, and the ink ejection main body 11 on the head substrate 10.
Temperature sensor (temperature measuring means) 12 for measuring temperature in the vicinity
And a flexible cable is connected, and a flexible cable connecting portion 13 for inputting and outputting a signal to and from the ink discharge portion main body portion 11 and the temperature sensor 12 is installed. The ink ejection main body 11 is provided with a plurality of ejection ports 14 for ejecting ink along the center line of the surface (nozzle surface 15) facing the recording paper 2. It communicates with the nozzle (flow path). The recording head 3 is installed on the carriage 4 in a state in which one end of the nozzle surface 15 is inclined so as to be lower than the other end.

The temperature sensor 12 is the ink discharge main body 1
The air temperature near 1 or the temperature of the head substrate 10 is measured, and is electrically connected to the control unit through the flexible cable connection unit 13.

As shown in FIG. 2, the carriage 4 is provided with a plurality of recording heads 3 for each color (yellow, magenta, cyan, black).

The maintenance unit 5 covers the ejection port and sucks ink from the ejection port 14 and a nozzle surface 15 after the suction cap 16 sucks the ink. A blade 17 for wiping off the remaining ink, and although not shown in FIG.
And a blade cleaner portion for cleaning the blade.

A plurality of (two in the present embodiment) suction caps 16 are provided side by side, and a plurality of recording heads 3 can be suctioned at one time during maintenance. FIG. 4 is a schematic diagram showing an ink suction unit including the suction cap 16 and the suction means 20. The suction cap 16 covers the periphery of the nozzle surface 15 of the recording head 3 and maintains the airtightness. Further, a lip portion 19 having elasticity is provided. Further, a suction pump (suction means) 20 for sucking inside the space formed by the suction cap 16 and the nozzle surface 15 and an atmosphere communication valve 21 are connected to the back surface of the suction cap 16.
The suction pump 20 sucks the nozzle surface 15 which is covered and sealed by the suction cap 16 through the suction cap 16. Then, the ink sucked from the ejection port 14 by the suction pump 20 is discharged to the waste ink tank 22.

Further, when the suction cap 16 is separated from the nozzle 15 after suction, it is arranged such that one end portion side is separated first and the other end portion is gradually separated. The suction cap 16 is supported on the side surface by a substantially L-shaped support piece 18, and is arranged so as to be substantially opposed to the nozzle surface 15 of the recording head 3.

In the present embodiment, the suction pump 20 is illustrated as the suction means, but any suction pump may be used as long as it sucks ink from the discharge port 14, and examples thereof include a piston and a cylinder. To be

The support piece 18 is composed of a body portion 23 for supporting the suction cap 16 and an extending portion 24 extending at a right angle from the lower end of the body portion 23. The body portion 23 and the extending portion 24. The joint is rotatably supported at the joint. Then, the extending portion 24 has a substantially elliptical cam (moving means) 26.
Are in contact. By rotating the cam 26, the support piece 18 is rotated, and accordingly, the suction cap 16 is attached to and detached from the nozzle surface 15 of the recording head 3.

The cam drive shaft 27 of the cam 26 is connected to a cam drive unit such as a motor, and is rotated by the control of the cam drive unit, and the suction cap 16 is separated from the recording head 3 at a predetermined position. (Standby position; FIG. 4C) and a position where the nozzle surface 15 is covered and sealed (FIG. 4A).

FIG. 5 is a schematic view showing the structure of a wiping unit including a blade and a blade cleaner section.
The blade 17 is formed of an elastic body and has a suction cap 16
After the end of the ink suction by, the blade main body 35 for wiping off the ink remaining on the nozzle surface 15 and the blade movable part 36 for supporting the blade main body 35 and moving it up and down (arrow E) are provided.

Further, the blade cleaner 37 is installed inside the maintenance unit 5, and an ink absorber 38 for absorbing and wiping the ink of the blade main body 35 and an absorber holder 39 for holding the ink absorber 38. Is equipped with.

As shown in FIG. 2, the home position 7 is provided with the same number of moisturizing caps 8 for moisturizing the nozzle surface 15 as the recording heads 3, and when the carriage 4 is on standby, the recording heads 3 are provided. The nozzle surface 15 is covered and hermetically sealed.

When maintenance is started, first, the recording head 3 is moved by the movement of the carriage 4 and the suction cap 1 is moved.
Move to 6.

The movement of the carriage 4 is carried out by driving a carriage driving unit (not shown), and
When the carriage sensor detects that the carriage 4 has moved to the suction position, the carriage drive unit stops and the carriage stops.

When the carriage 4 is stopped at the suction position, the suction cap 16 moves to the nozzle surface 15 of the recording head 3 by the cam driving portion (not shown), and seals the nozzle surface 15 of the recording head 3. The discharge port 14 is covered.

In this state, the operation of the suction pump 20 is started and the ink is sucked from the ejection port 14. This suction is performed until a predetermined time has elapsed, and is repeated a predetermined number of times.

When the suction pump 20 is stopped, thereafter, the atmosphere communication valve 21 is opened so that the suction cap 16 and the nozzle surface 15 can be easily separated from each other, and then the suction cap 1
6 is moved to the standby position.

Further, when the suction cap 16 is stopped,
The atmosphere communication valve 21 is closed, and the carriage 4 is attached to the nozzle surface 15
The carriage driving unit moves the guide rail 6 up to the blade 17 for wiping.

When it is detected that the carriage 4 has moved to the wipe position, the carriage drive unit stops and the carriage stops.

When the carriage 4 stops at the wipe position,
The blade 17 starts moving. When the blade 17 stops at the wipe position, the carriage 4 moves and starts wiping. By moving the carriage 4 at a constant speed,
The blade wipes the nozzle surface 15 of the recording head at a constant speed (adjusted by the overlap between the nozzle surface and the tip of the blade) with a proper pressure to clean ink droplets adhering to the nozzle surface.

Suction and subsequent wiping are continuously performed as described above. For example, first, the Y and M recording heads are sucked by the two suction caps.
Then, the blade wipes the Y head and then the M head. After that, ink is sucked from each of the C and K heads, and then each head is sequentially wiped by a blade to perform cleaning.

In the present invention, as described above, the wiping speed V _w of each recording head (ink) is set to a value determined by the backward meniscus speed RMV of the ink, whereby the overall cleaning time can be shortened. . Wiping speed V _w is in the range of 10~100mm / sec.

The blade 17 is cleaned by the blade cleaner section 37 at the end of each wiping.

When the cleaning of the blade 17 is completed, the carriage 4 moves to the home position 7 which is the standby position and stops.

The wiping by the blade and the cleaning of the blade will be described. When the maintenance is not performed, the blade 17 stands by below the ink absorber 38 of the blade cleaner portion 37 as shown in FIG. 5A. There is. When the nozzle surface 15 needs to be wiped, the blade movable unit 36 moves upward, thereby moving the blade main body 35 upward. During this movement, the upper surface of the blade body and the ink absorber 38 come into contact with each other. That is, the ink remaining on the blade body 35 is absorbed by the ink absorber 38 by this operation. With such a configuration, the blade body 35 is cleaned every time maintenance is performed, and it is possible to prevent deterioration of the blade body 35 due to residual ink.

Further, when the blade movable portion 36 rises and the upper end of the blade main body 35 reaches the nozzle surface passing position F, the carriage 4 operates, and the upper surface of the blade main body 35 and the nozzle surface of the recording head 3 are operated. The ink that comes into contact with and remains on the nozzle surface 15 is wiped off by the blade body 35.

In the present embodiment, the upper surface of the blade body 35 and the nozzle surface 15 contact each other, so that the nozzle surface 15
Since the ink remaining on the upper portion is wiped off, the upper surface side of the blade main body 35 is wiped off when the blade main body 35 is cleaned.

Next, the ink-repellent surface forming the nozzle surface of the recording head for wiping with the blade will be described. When a water-based ink is used, the nozzle surface of the recording head is made of a water-repellent and ink-repellent material.
In order to make the nozzle surface water-repellent (ink-repellent), a water-repellent coating is usually applied to the material forming the nozzle surface, for example, plastics such as polyester and polyamide, materials such as glass, ceramics and metals.

Regarding the method of applying a water-repellent or ink-repellent coating so that ink does not adhere to the nozzle surface, see, for example, Japanese Patent Publication No. 52-24821 and Japanese Patent Laid-Open No. 56-286.
Polytetrafluoroethylene (PTFE) described in No. 2
A method of coating a material having ink repellent characteristics such as fluororesin or silicone resin, etc.
No. 72866, No. 60-255441, etc., there is a method of using a tetrafluoroethylene-hexafluoropropylene copolymer (FEP) as the ink repellent film. This FEP is polytetrafluoroethylene (PTF
While having a low surface energy (ink repellency) equivalent to that of E), the viscosity at the time of heating and melting is lower than that of PTFE,
When a uniform film is formed by applying an aqueous dispersion and heating and melting, a uniform film can be obtained at a temperature lower than that of PTFE in a short time, and the film forming processability is excellent. Also, Japanese Patent Laid-Open No. 2001-7150
No. 9, a method of mixing and coating an FEP aqueous dispersion and a silica sol particle dispersion, drying and baking at 300 to 400 ° C., and a method using a fluorine-containing polysiloxane compound in JP-A-10-505870. Is listed.

Even if the blade for cleaning the nozzle surface on the front surface of the recording head is ink-philic (hydrophilic),
Although it may have ink repellency (water repellency), for example, various rubbers such as butyl rubber, chloroprene rubber, ethylene / propylene rubber and the like, which have elasticity, have a thickness of 0.5 mm to 2
It is selected from materials of about mm.

For example, a blade material such as urethane rubber or butyl rubber, which is an ink-philic (hydrophilic) material having a contact angle with ink of 40 degrees or less, is coated with a silane compound, or a hydrophilic polymer (eg, nylon, Examples thereof include those made hydrophilic by so-called surface modification by coating with polyurethane, polyvinyl alcohol, etc.) or by subjecting the rubber surface to plasma treatment in advance.

Further, for example, the contact angle with respect to the ink is 40.
As a blade material having an ink-repellent and water-repellent surface larger than that, butyl rubber, silicone rubber, or a plastic substrate surface having elasticity, for example, made of a water-repellent polymer resin such as polytetrafluoroethylene, or these Examples of such materials include resin-coated materials.

When a relatively hydrophilic blade such as urethane rubber is used, its affinity allows the ink to be attracted and wiped off. However, due to its hydrophilicity, ink droplets may be drawn again (from the nozzle) to the cleaned nozzle surface, and the blade is rather made of a material having weak ink affinity and ink repellency. It is preferable that the ink droplets are not pulled out from the nozzles and the blade itself is less contaminated.

Therefore, a silicone rubber material is preferable as the blade material. When evaluated by the contact angle with respect to the ink, a material having a contact angle of 50 degrees or more is preferable.

The RMV value of the ink with respect to the nozzle surface varies depending on the combination of the water repellency of the nozzle surface of the recording head and the material of the ink repellent surface and the ink. Even if the ink viscosity and surface tension are the same, they are not necessarily the same. In addition, the composition of the ink has a complicated effect. Therefore, for example, the four color inks (Y, M, C, Bk) used in a color ink jet recording apparatus are often different. Therefore, for example, when the RMV of the C ink is the smallest and all the remaining inks are larger than this, for the recording head using the C ink, for example, the wiping speed by the blade is 10 mm / se.
As c, wipe the nozzle surface without ink residue,
For other recording heads that use large RMV ink, efficient cleaning can be performed by wiping at a faster wiping speed (for example, 60 mm / sec) that matches the RMV value of the ink. As a result, it is not necessary to forcibly match the RMV values of the respective inks, and it is not necessary to set the wiping speed in accordance with the recording head where the ink is likely to remain, thus shortening the cleaning time.

The ink contact angle is used to measure and evaluate the ink repellency of the nozzle surface and the ink repellency of the blade.
The ink contact angle is measured by placing an ink drop on the surface of the material whose contact angle is to be measured. In the present invention, the evaluation is performed by using the dynamic receding contact angle, and FIG. 6 schematically shows the method for measuring the dynamic receding contact angle θ. The dynamic receding contact angle means that the ink droplet c adhering to the sample surface a (the sample to be measured, in this case, the nozzle surface, the blade, or the solid surface of the same material used for them) is sucked from the needle b. The contact angle θ formed when the above is performed.

In the present invention, this dynamic receding contact angle θ
Is the value measured by the expansion contraction method using an automatic contact angle meter CA-V type (manufactured by Kyowa Interface Science Co., Ltd.). In the measurement, the measurement temperature was 25 ° C., the initial ink droplet volume at the start of the measurement was 15 μl, and the droplet suction speed was 5 μl / sec. The contact angle θ was dynamically set back 1.5 seconds after the suction was started. The contact angle was taken as the contact angle.

In the ink jet recording apparatus according to the present invention, an aqueous ink containing 10% by mass or more of water based on the total mass of the ink is used, and the coloring agent used in the ink is a water-soluble dye such as an acid dye, Direct dyes, reactive dyes, disperse dyes, pigments and the like can be used.

In particular, in the case of pigment ink, when the solvent or water evaporates and adheres from the ink droplets remaining on the nozzle surface, the pigment is basically insoluble in the solvent and therefore does not redissolve like a dye, or a hard mass. Therefore, if it is taken into the nozzle, ejection failure is likely to occur, and the nozzle surface cleaning performance is significantly affected as compared with ink that uses a dye as a colorant, such as scratching the nozzle surface and further the blade material. Therefore, reducing wiping residue on the nozzle surface by setting the wiping speed according to the RMV value of the ink as in the present invention is particularly great in the case of water-based ink using a pigment as a colorant. Pigment ink also
It is also preferable from the viewpoint of the storability of the obtained image record.

As the pigment used in the pigment ink, organic pigments such as insoluble pigments and lake pigments, and carbon black can be preferably used.

The insoluble pigment is not particularly limited, but for example, azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindoline, azine, oxazine. ,
Thiazine, dioxazine, thiazole, phthalocyanine, diketopyrrolopyrrole and the like are preferable.

Specific pigments which can be preferably used include the following pigments. Examples of magenta or red pigments include C.I. I. Pigment Red 2, C.I. I. Pigment Red 3, C.I. I. Pigment Red 5, C.I. I. Pigment Red 6, C.I. I. Pigment Red 7, C.I. I. Pigment Red 15,
C. I. Pigment Red 16, C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 53: 1,
C. I. Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123,
C. I. Pigment Red 139, C.I. I. Pigment Red 144, C.I. I. Pigment Red 149, C.I.
I. Pigment Red 166, C.I. I. Pigment Red 177, C.I. I. Pigment Red 178, C.I. I.
Pigment Red 222 and the like.

Examples of pigments for orange or yellow include C.I. I. Pigment Orange 31, C.I.
I. Pigment Orange 43, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I.
Pigment Yellow 14, C.I. I. Pigment Yellow 15, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 9
3, C.I. I. Pigment Yellow 94, C.I. I. Pigment Yellow 128, C.I. I. Pigment Yellow 13
8 etc. are mentioned.

As the pigment for green or cyan,
For example, C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 1
5: 3, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 60, C.I. I. Pigment Green 7 and the like.

A pigment dispersant may be used for these pigments if necessary, and examples of the pigment dispersant that can be used include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonic acids. Salt, sulfosuccinate, naphthalene sulfonate, alkyl phosphate,
Activator such as polyoxyalkylene alkyl ether phosphate, polyoxyalkylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, polyoxyethylene fatty acid amide, amine oxide, or styrene, styrene derivative, vinyl Block copolymers of two or more monomers selected from naphthalene derivatives, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, fumaric acid derivatives, random copolymers Mention may be made of polymers and their salts.

Of these, those having a molecular weight of 3,000 or more are preferable, and styrene, styrene derivatives,
Block copolymer composed of two or more kinds of monomers selected from vinyl naphthalene derivative, acrylic acid, acrylic acid derivative, maleic acid, maleic acid derivative, itaconic acid, itaconic acid derivative, fumaric acid, fumaric acid derivative, random A polymer dispersant comprising a copolymer and a salt thereof is preferable, and among these, styrene, acrylic acid, an acrylate ester having a molecular weight of 3,000 or more,
A block copolymer and a random copolymer selected from methacrylic acid and methacrylic acid ester are preferable. Examples of these are styrene-acrylic acid-methyl methacrylate copolymer (molecular weight 10,000, acid value 160), and acrylic-styrene resin, Joncryl 6
1 (manufactured by Johnson Co.) and the like are available.

It is preferable to use a polymer dispersant having a molecular weight of 3,000 or more from the viewpoint of dispersion stability, but if the affinity with the pigment, the molecular weight, and the addition amount are not appropriate, the ink remains on the nozzle surface of the recording head. Occurs and has a considerable influence on the emission. In particular, regarding the ink residue on the nozzle surface of the pigment ink containing the polymer, the tracking of the polymer component influences the dynamic ink behavior. It is not enough and the measurement of RMV becomes important.

Since the preferred method of using the polymer is influenced by the pigment used, the ink composition, etc., it cannot be said unconditionally, but an ink having a high RMV can be obtained by selecting and evaluating by the RMV evaluation method shown in the present invention. It is preferable to select (1) to increase the cleaning speed.

As a method for dispersing the pigment, various dispersing machines such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill and a paint shaker can be used. it can. Also,
It is also preferable to use a centrifugal separator and a filter for the purpose of removing coarse particles of the pigment dispersion.

The average particle size of the pigment particles in the pigment ink is selected in consideration of stability in the ink, image density, glossiness, light resistance, etc. In addition, in the image forming method of the present invention,
From the viewpoint of improving gloss and improving texture, it is preferable to appropriately select the particle size. In the present invention, the reason why the glossiness or texture is improved is not clear at this stage, but in the formed image, the pigment is in a state in which it is preferably dispersed in the film in which the thermoplastic resin is melted. Presumed to be related to. For the purpose of high-speed treatment, it is necessary to melt the thermoplastic resin into a film in a short time and further sufficiently disperse the pigment in the film. At this time, it is considered that the surface area of the pigment has a great influence, and therefore the average particle size has an optimum region.

The water-based ink composition, which is a preferred form of the pigment ink, is preferably used in combination with a water-soluble organic solvent. Examples of the water-soluble organic solvent that can be used in the present invention include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl). Alcohol, etc.), polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol,
Hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc.), polyhydric alcohol ethers (for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether,
Ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monoethyl ether Butyl ether, ethylene glycol monophenyl ether, propylene glycol monophenyl ether, etc.),
Amines (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine,
N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.),
Amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocycles (eg, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone, 1, 3-dimethyl-2-imidazolidinone etc.), sulfoxides (eg dimethyl sulfoxide etc.), sulfones (eg sulfolane etc.), urea, acetonitrile, acetone and the like. Examples of preferable water-soluble organic solvent include polyhydric alcohols. further,
It is particularly preferable to use a polyhydric alcohol and a polyhydric alcohol ether together.

The water-soluble organic solvent may be used alone or in combination of two or more. The total amount of the water-soluble organic solvent added to the ink is 5 to 60% by mass, preferably 10 to
It is 35 mass%.

The ink composition may contain various known additives, if necessary, depending on the purpose of improving ejection stability, compatibility with print heads and ink cartridges, storage stability, image storability, and other performance improvements. For example, a viscosity modifier, a surface tension modifier, a specific resistance modifier, a film-forming agent, a dispersant, a surfactant, a UV absorber, an antioxidant, an anti-fading agent, an anti-fouling agent, an anticorrosive agent, etc. are appropriately selected. For example, polystyrene, polyacrylic acid esters, polymethacrylic acid esters, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or copolymers thereof, urea resins, or Organic latex fine particles such as melamine resin, liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, etc. Droplet particles, various surfactants of cationic or nonionic, JP 57-74193,
UV absorbers described in JP-A-57-87988 and JP-A-62-261476, JP-A-57-74192 and 57.
-87989, 60-72785, 61-14.
6591, JP-A-1-95091 and 3-133.
No. 76, etc., anti-fading agent, JP-A-59-4
2993, 59-52689, 62-2800.
69, 61-242871, and JP-A-4-21.
Examples thereof include fluorescent whitening agents, pH adjusting agents such as sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate and the like described in No. 9266.

The viscosity of the ink composition during flight is preferably 40 mPa · s or less, more preferably 30 mPa · s or less. The surface tension of the ink composition during flight is preferably 20 mN / m or more,
More preferably, it is 30 to 45 mN / m.

The pigment solid content concentration in the ink is 0.1 to 1
In order to obtain a photographic image, it is preferable to use so-called dark and light inks having different pigment solid content concentrations, and as described above, yellow, magenta, cyan, and black light and dark inks are used. Is particularly preferable. In addition, it is also preferable from the viewpoint of color reproducibility to use special color inks such as red, green and blue, if necessary.

[0084]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

Example 1 Konica inkjet printer IGUAZU 104
Using 4SD (schematic diagram is shown in FIG. 2), the following tests were conducted.

(Production of Nozzle Plate) An oxygen plasma treatment (13.56 MHz, 2) was performed using a 125 μm-thick polyimide sheet (Ubilex, manufactured by Ube Industries, Ltd.).
00W, 10 Pa, 3 minutes), and then apply a coating solution having the following composition with a wire bar to a dry film thickness of 0.8 μm, and bake at 330 ° for 2 hours to perform an ink repellent treatment and nozzle. A plate was made.

FEP dispersion liquid (manufactured by Daikin Industries, Ltd., NEOFLON ND-1) 10 parts by mass Silica sol particle dispersion liquid (manufactured by Catalysis Chemical Co., Ltd., Cataloid S-30H) 0.02 parts by mass Water 90 parts by mass Nozzle In order to evaluate the ink repellency of the plate surface,
When the magenta ink was selected from the inks prepared below and the receding contact angle was measured using a contact angle meter CA-X manufactured by Kyowa Interface Science Co., Ltd., the nozzle plate produced was 66 °.

Next, the nozzle plate which has been subjected to the ink repellent treatment was subjected to nozzle hole processing using an excimer laser.
The number of nozzles was 128 and the nozzle diameter was 40 μm.

After forming the nozzle, a recording head using the nozzle plate was prepared. Next, the produced recording head was mounted as a head of the Konica inkjet printer. The blade material of the maintenance unit was made of silicone rubber having a thickness of 1 mm (silicon rubber IS-825 50HS manufactured by Irumagawa Rubber Co., Ltd.). Further, the drive system of the carriage is changed so that the wiping speed by the blade can be changed stepwise.

Then, the following inks were prepared. (Yellow pigment dispersion) C.I. I. Pigment Yellow 128 150 g Styrene-acrylic acid-methyl methacrylate copolymer 40 g (molecular weight 10,000, acid value 160) ethylene glycol 100 g glycerin 80 g ion-exchanged water 200 g are mixed, and 0.3 mm zirconia beads are mixed at a volume ratio of 6
Dispersion was carried out using a horizontal bead mill (System Zetamini manufactured by Ashizawa Co., Ltd.) filled with 0% to obtain a yellow pigment dispersion. The average particle size of the obtained yellow pigment dispersion is 121.
was nm. The average particle size is measured by Zetasizer 100.
0 (made by Malvern) was used.

<Yellow Ink> Yellow Pigment Dispersion 3 167 g Ethylene glycol 200 g Diethylene glycol 120 g Olfine 1010 (manufactured by Nisshin Chemical Co., Ltd.) 4 g Proxel GXL (manufactured by Zeneca) 2 g or more are ion-exchanged water to 1000 g, and 1 μm A yellow ink was prepared by passing through a Millipore filter twice.

(Magenta Pigment Dispersion) C.I. I. Pigment Red 122 100 g Johncryl 61 (acrylic-styrene resin, manufactured by Johnson) 40 g Ethylene glycol 100 g Ion-exchanged water 130 g are mixed, and 0.3 mm zirconia beads are mixed at a volume ratio of 6
After dispersion using a horizontal bead mill (System Zetamini manufactured by Ashizawa Co., Ltd.) filled with 0%, 20,000 rp
Centrifuging at m for 30 minutes gave a magenta pigment dispersion. The average particle size of the obtained magenta pigment dispersion is 35.
was nm.

<Magenta ink> Magenta pigment dispersion 140 g Diethylene glycol 180 g Glycerin 80 g Hydrophilic silicone compound 1 (KF700, manufactured by Shin-Etsu Silicone Co., Ltd.) 4 g Perex OT-P (manufactured by Kao Corporation) 5 g Proxel GXL (manufactured by Zeneca) ) 2 g or more was made up to 1000 g with ion-exchanged water and passed through a 1 μm Millipore filter twice to prepare magenta ink.

(Preparation of Cyan Pigment Dispersion) C.I. I. Pigment Blue 15: 3 250 g Acrylic acid-methyl acrylate-ethyl methacrylate copolymer (molecular weight 15,000, acid value 160) 110 g Diethylene glycol 100 g Ion-exchanged water 500 g are mixed, and 0.3 mm zirconia beads are mixed at a volume ratio of 6
Dispersion was performed using a horizontal bead mill (System Zetamini manufactured by Ashizawa Co., Ltd.) filled with 0% to obtain a cyan pigment dispersion. The average particle size of the obtained cyan pigment dispersion was 95 nm.

<Cyan Ink> Cyan Pigment Dispersion 100 g Ethylene glycol 300 g Diethylene glycol monobutyl ether 100 g Pluronic L-44 (manufactured by Asahi Denka Co., Ltd.) 10 g Ion-exchanged water 490 g The above ink is passed through a 1 μm Millipore filter twice to give cyan ink. Was prepared.

(Preparation of Black Pigment Dispersion) Carbon black 250 g Styrene-acrylic acid copolymer 75 g (solid content) (Molecular weight 7,000, acid value 150) Glycerin 100 g Ion-exchanged water 550 g were mixed to obtain 0.3 mm Zirconia beads in volume ratio of 6
A horizontal bead mill (System Zetamini manufactured by Ashizawa Co., Ltd.) filled with 0% was used for dispersion to obtain a black pigment dispersion. The average particle size of the obtained black pigment dispersion is 75n.
It was m.

<Black Ink> Black Pigment Dispersion 150 g Ethylene glycol 200 g Triethylene glycol monoethyl ether 50 g Perex OP-T (manufactured by Kao Corporation) 2 g Ion-exchanged water 598 g The above components are passed through a 1 μm Millipore filter twice. A black ink was prepared.

Table 1 shows the results of measuring the RMV value on the surface of the nozzle plate for each of the prepared inks using the apparatus shown in FIG.

[0099]

[Table 1]

Then, all the ink cartridges of the ink jet printer were filled with magenta ink, and as shown in Table 2 with a magenta single color, the wiping speed (V _w )
The cleaning tests 1 to 5 were performed by changing the number of steps to five.
That is, after performing a cleaning test of the recording head nozzle surface including ink suction by a suction cap and wiping by a blade, the cover was opened and the wiping residue of ink on the nozzle surface of the recording head of the printer was observed. Wiping speed is 1.5 for each RMV of ink
6, 1.17, 0.88, 0.68 and 0.29 (coefficient k in Table 2) times the value, 80 mm / se
c, 60 mm / sec, 45 mm / sec, 35 mm /
sec and 15 mm / sec. The wiping dust was evaluated according to the following criteria.

(Wipe residue) ○: No ink wipe residue was observed around the nozzles of all heads. △: A small amount of ink residue was found around the nozzles of some heads. ×: All Table 2 shows the above results in which the ink of wiping dust was clearly seen around the nozzles of the head.

[0102]

[Table 2]

It can be seen that the recording head was cleaned at a wiping speed in the range of the present invention which was 1.1 times or less the coefficient k in the table with respect to the RMV of the ink, and it was found that there was no wiping residue. The maintenance time can be shortened as the wiping speed (V _w ) becomes faster.

Example 2 Further, instead of the magenta ink, the yellow, magenta, cyan and black inks prepared as described above were filled in the respective ink cartridges of the printer to obtain a color printer.

By controlling the drive system of the carriage, the wiping speed of the recording head for ejecting each ink (actually, since the carriage moves, the moving speed of the carriage) is shown in Table 3 based on the RMV of each ink. The k value was changed to a different value, and different values were set, and the cleaning test was conducted in the same manner as described above (Tests 6 and 7). or,
As a comparison, the wiping of each recording head is performed at a constant speed, that is, 20 mm / sec, 30 mm / msec, 50 mm.
/ Sec was changed in 3 steps and the cleaning test was conducted in the same manner (tests 8 to 10). In addition, in each test, the wiping time for each ink is shown in Table 3 as a relative value with test 8 being 100.

The ink wiping residue was evaluated by observing each head as follows. ○: There is no dust on the ink. X: There is dust on the ink.

[0107]

[Table 3]

It can be seen that the ink wiping does not occur for each recording head cleaned at the wiping speed within the range of the present invention with respect to the RMV of each ink.
Further, looking at tests 8 to 10 in which cleaning was performed at the same wiping speed for all recording heads, in order to eliminate wiping residue in all recording heads, all recording heads were wiped at the wiping speed for the ink having the smallest RMV. It turns out that the wiping speed of must be adjusted. That is, in Test 9, the cyan ink head was
Further, in Test 10, the yellow, cyan, and black heads can be wiped off, respectively, but in Test 8 in which the wiping speed is the slowest, the wiping speed of all recording heads is within the range of the present invention, and It can be seen that no wipe dust is generated.

Further, in Tests 6 and 7 in which different wiping speeds were set for the respective ink recording heads based on the RMV of the ink, there was no wiping of the ink at all, and the relative speeds of cleaning were compared. It can be seen that the total cleaning time is short and the cleaning efficiency is good as compared with the test 8 in which all the recording heads are free from ink wiping.

[0110]

According to the present invention, it is possible to provide an ink jet recording apparatus in which the nozzle surface of the recording head is less likely to be wiped and the cleaning efficiency is high.

[Brief description of drawings]

FIG. 1 is a diagram showing a method for measuring an RMV value.

FIG. 2 is a schematic diagram showing an example of a main configuration of an inkjet recording apparatus.

FIG. 3 is a schematic diagram showing a configuration of a recording head.

FIG. 4 is a configuration diagram showing an outline of an ink suction unit.

FIG. 5 is a schematic diagram showing a configuration of a wiping unit.

FIG. 6 is a diagram showing a method of measuring a dynamic receding contact angle θ.

[Explanation of symbols]

1 Inkjet recording device 3 recording head 5 Maintenance unit 16 suction cap 17 blade

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hirotaka Iijima             Konica Stock Market, 1 Sakura-cho, Hino City, Tokyo             In-house (72) Inventor Masaaki Takasaki             Konica Stock Market, 1 Sakura-cho, Hino City, Tokyo             In-house F term (reference) 2C056 EA16 EC23 FA10 HA24 JA05                       JA13 JB02 JB04 JB08 JB09

Claims (4)

[Claims] 1. An ink jet recording apparatus comprising a recording head and a cleaning mechanism for wiping a nozzle surface of the recording head with a blade, and a retreating meniscus velocity (RMV) of ink ejected from nozzles of the recording head with respect to the nozzle surface, An ink jet recording apparatus characterized in that a speed (V _w ) at which a blade wipes a nozzle surface has the following relationship. V _w ≦ 1.1 × RMV 2. An ink jet recording apparatus comprising a recording head and a cleaning mechanism for wiping a nozzle surface of the recording head with a blade, and a retreating meniscus velocity (RMV) of ink ejected from nozzles of the recording head with respect to the nozzle surface, An ink jet recording apparatus characterized in that a speed (V _w ) at which a blade wipes a nozzle surface has the following relationship. 0.5 x RMV ≤ V _w ≤ 1.1 x RMV 3. An ink jet recording apparatus comprising a plurality of recording heads and a cleaning mechanism for wiping a nozzle surface of the recording heads with a blade, wherein each recording head retreats ink ejected from nozzles of the recording head. An inkjet recording apparatus having the following relationship between a meniscus speed (RMV) and a speed (V _w ) at which a blade wipes a nozzle surface of a recording head. 0.5 x RMV ≤ V _w ≤ 1.1 x RMV 4. A pigment ink containing a polymer component having a molecular weight of 3000 or more is used.
5. The inkjet recording device according to any one of 1.