JPH08337748A - Aqueous ink, inkjet recording method and recording apparatus using the same - Google Patents

Abstract

(57) [Summary] [Object] To provide a water-based ink which prevents bronzing phenomenon and exhibits a high optical density, an inkjet recording method, and an inkjet recording apparatus using the same. [Composition] In a water-based ink containing a color material and a liquid medium,
An aqueous ink containing a branched water-soluble polymer selected from branched polyvinyl alcohol and branched polyether. An ink jet recording method and a recording apparatus which perform recording by ejecting ink droplets from an orifice of a recording head on a recording material using the ink according to a recording signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based ink jet recording method in which ink is ejected and ejected as small droplets from an ejection port (orifice), and the small droplets are adhered to the surface of a recording material for recording. Ink, ink jet recording method using the same, equipment and recording apparatus using such ink, in particular, eliminating bronze phenomenon, realizing high optical density recording, and improving performance such as ejection stability and ejection responsiveness To do.

[0002]

2. Description of the Related Art Conventionally, as ink jet recording inks, water-based inks have been the mainstream in terms of ease of ejection, safety, odor, etc., and various water-soluble dyes or pigments have been mixed with water or water and water-soluble organic solvents. There is known an ink in which a humectant, a dye dissolution aid, an antifungal agent or the like is added after being dissolved or dispersed, if necessary.

These ink jet recordings are capable of ejecting several thousand drops or more of ink per second, easy high-speed recording, little noise, easy colorization, high resolution, and plain paper. It has many advantages such as being able to record, and has been popular for several years.

Further, in recent years, due to cost reduction, high performance of personal computers, and standardization of GUI environment, demands for high color development, high quality, high resolution recording, and high speed recording are also increasing in image recording of printers, etc. A technical idea is being proposed to make the color clearer and reduce bleeding (feathering) and color bleeding (bleeding).

In the flow of such technical development, it is general that the ink for ink jet recording uses a dye as a coloring material. In order to obtain a sufficient image density, it is necessary to increase the dye content in the ink to 10% by weight or more, but the solubility of the dye is lower than this, and the higher the content, the higher the viscosity or crystallization at low temperature. Cheap. (Tokuya Ota “Nikkei Electronics” No. 1982.1.8,
(P. 160)

Further, in the ink jet recording ink, a solvent having a low vapor pressure such as glycols is used in order to prevent clogging of fine nozzles. However, if water is evaporated at the tip of the nozzle, crystallization occurs if the dye is dissolved in water but not in glycols. Therefore, a good solvent is recommended that has high dye solubility and low vapor pressure.

As a first example thereof, Japanese Patent Laid-Open No. 54-161.
No. 403 publication discloses that as an aqueous ink solvent capable of clear recording without causing bleeding or strike-through regardless of paper quality,
N-alkanolamines are disclosed.

A second example is Japanese Patent Laid-Open No. 62-897.
JP-A-76 discloses an ink containing an alkylene oxide compound represented by the following general formula, having a sufficient drying / fixing rate for various recording materials and capable of obtaining a high-quality image. .

[0009]

Embedded image HO (C ₂ H ₄ O) _a (C ₃ H ₆ O) _b (C ₂
H ₄ O) _c H

Further, as a third example, Japanese Patent Laid-Open No. 5-331.
Japanese Patent No. 395 discloses that when a water-based ink composed of water, a coloring material and a water-soluble polymer is used, the water resistance of a printed matter is improved, bleeding is prevented, and nozzle clogging is less likely to occur. In this example, polyvinyl alcohols are recommended as the water-soluble polymer.

[0011]

The first example of the prior art described above is sufficient in terms of dye solubility, low vapor pressure, etc., but the ink containing alkanolamine has a high p
Since it becomes H (pH> 10), there is a problem that the constituent members of the recording head are corroded or dissolved in the long term.

The second example is only the effect of enhancing the penetrability into paper, and the hue changes when the dye is deposited on the paper (this phenomenon is called bronze in the case of black ink). It cannot be prevented. In the third example, although the water resistance can be improved, the optical density is around 1.3 and there is no particular effect.

The physical properties required for jetting small droplets of water-based ink, especially ink jet ink, are surface tension;> 20d.
yne / cm (related to refill rate), viscosity; 1
˜20 mPa · s, pH: 3 to 10, fixing time is <20 sec (preferably as short as possible), and the recording performance is optical density when the image density on the recording material is black ink. It must be 1.4 or more.

The present invention has been made in order to solve the above-mentioned conventional problems, and can prevent bronzing phenomenon, exhibit high optical density, and perform recording with good feathering, ejection stability, and ejection response. Another object of the present invention is to provide a water-based ink, an ink jet recording method and a recording apparatus using the same.

[0015]

That is, the present invention is an aqueous ink containing a coloring material and a liquid medium, which contains a branched water-soluble polymer.

Further, the present invention provides an ink jet recording method for recording on a recording material by ejecting ink droplets containing a coloring material and a liquid medium from an orifice of a recording head in response to a recording signal. It is an inkjet recording method for recording using the above-mentioned water-based ink.

Furthermore, the present invention is a recording unit comprising an ink containing portion containing ink and a recording head portion for ejecting ink as ink droplets, wherein the ink is the above-mentioned aqueous ink.

Further, the present invention is an ink jet recording apparatus having a recording unit provided with an ink containing section for containing ink and a recording head section for ejecting ink as ink droplets, and the recording unit used in the apparatus is the above-mentioned. The inkjet recording device is a recording unit.

The present invention will be described in detail below. The aqueous ink of the present invention is an ink comprising a liquid composition containing a coloring material and a liquid medium, and contains a branched water-soluble polymer composed of at least one selected from branched polyvinyl alcohol and branched polyether. It is characterized by doing. The inventors of the present invention, as a result of intensive studies to clarify the bronze phenomenon, have found that the bronze is a change in color due to crystallization or association of dye molecules on paper.

An example will be described below with reference to FIG. First, an ink having the following composition was prepared as a conventional water-based ink (a), and a black filled pattern was recorded on an electrophotographic recording plain paper (NP-SK paper) with an inkjet printer BJ300 (manufactured by Canon Inc.).

(Conventional Ink) Dye C.I. I. Food Black-2 8.0% by weight Solvent Polyethylene glycol 300 10.0% by weight Water 82.0% by weight * Polyethylene glycol 300 is manufactured by Wako Pure Chemical Industries, Ltd.

Next, as the ink (b) of the present invention, an ink having the following composition was prepared and recorded in the same manner as in the conventional example. (Ink of the Present Invention) Dye C.I. I. Food Black-2 8.0% by weight Solvent Branched polyvinyl alcohol 10.0% by weight Water 82.0% by weight * Branched polyvinyl alcohol is 0.4% in Wako Pure Chemical Industries, Ltd. polyvinyl alcohol (polymerization degree 500) Is partially cross-linked by the addition of boric acid (H ₃ BO ₃ ), and has the structure shown in FIG. (See "New Experimental Chemistry Lecture 19, Polymer Chemistry 1" p310-311, edited by The Chemical Society of Japan, 1978)

A visual comparison of the above recorded products shows that the conventional example is a black with a greenish luster characteristic of the bronze phenomenon, and the recorded product of the present invention has a hue closer to pure black than the conventional example. .

Further, a part of the recorded matter for clarifying the phenomenon was cut into a 15 mm square, and the crystal state of the dye was examined by an X-ray diffractometer (MXP18 manufactured by Mac Science Co., Ltd.).
The diffraction pattern is shown in FIG. The measurement conditions are conventional,
The following conditions were applied to both examples of the present invention.

X-ray source: Cu (8.0 kW), sampling width: 0.020 deg, scanning range: 2θ = 5.00 °
~ 90.00 °, scanning speed: 3.00 deg / min,
Divergence slit: 1.00 deg, scattering slit: 1.0
0 deg, light receiving slit: 0.30 deg

FIG. 1A shows a conventional example, and FIG. 1B shows a diffraction pattern of the present invention. As is clear from the figure, the conventional example has a large number of clear diffraction peaks, whereas the example of the present invention does not have a strong diffraction peak and is considered to be almost amorphous. As a result, it was concluded that the bronzing phenomenon is due to the crystallization of the dye, and it is considered that the branched polyol of the present invention suppresses the bronze by interfering a large number of branch molecules between the dye molecules and inhibiting the crystallization of the dye. The polyethylene glycol used in the conventional example is a linear molecule and is unlikely to interrupt between dye molecules, so it is considered to have no effect on bronze suppression. In addition, a compound having a low molecular weight is not sufficiently large as compared with the size of the dye molecule, so that the mutual association of the dyes cannot be suppressed.

The branched polyol used in the above description is
The material is not limited to polyvinyl alcohol, and polyvinyl butyral and cellulose can be used as well. These polymers can be converted into branched molecules by partially cross-linking by a known method. That is, -O
Examples of the method for crosslinking the H group include the use of aldehydes, N-methylol compounds, dicarboxylic acids, dicarboxylic acid chlorides, bishalogen compounds, bisepoxides, bisaziridines, dimethylolethyleneureas, dimethylolureas, epichlorohydrin and the like. In addition, a vinyl-based monomer such as vinyl acetate can be used to obtain a branched polymer of a single substance by utilizing a chain transfer reaction.

Further, the branched water-soluble polymer of the present invention is
In addition to the branched polyol, branched polyether has the same effect. That is, it is considered that polyalkylene oxides have a large number of ether oxygens in the molecular chain and have the ability to coordinate the aqueous dye around the molecule by hydrogen bonding.

Specifically, polyethylene glycol, polypropylene glycol, polybutylene glycol, polyethylene glycol-polypropylene glycol diblock polymer, polyethylene glycol-polypropylene glycol-polyethylene glycol triblock polymer, etc. are added in a small amount of poly (meth) acrylic. Esterification with an acid gives a branched polyether.

As another method for obtaining a branched polyether, the main chain can be obtained by polymerizing the monomer represented by the following general formula (I) by a method such as solution, emulsion or suspension in the presence of a radical polymerization catalyst. A polymer having branched polyether chains is obtained from.

[0031]

Embedded image

In the above general formula (I), R ₁ is H or CH ₃ , R ₂ is H or an alkyl group having 1 to 30 carbon atoms,
Represents an (alkyl) phenyl group or (alkyl-substituted) aminoalkyl group, n is 2 to 4, m is 2 to 4, and L is 2
-4, x is 2-100, y is 0 or 1-100, z is an integer of 0 or -100, and n, m and L are the same numbers, and n and m or m and L. Except those with the same number.

The monomer represented by the general formula (I) has a structure in which an alkylene oxide is added to a vinyl (meth) acrylic acid monomer, and is ω-methoxypolyethylene glycol mono (meth) acrylate, ω-
Methoxy polyethylene glycol- (poly) propylene glycol monoacrylate, ω-methoxy polyethylene glycol- (poly) propylene glycol monomethacrylate, ω-ethoxy polyethylene glycol-
(Poly) propylene glycol monoacrylate, ω-
Ethoxy polyethylene glycol- (poly) propylene glycol monomethacrylate, ω-n-propyl polyethylene glycol- (poly) propylene glycol monoacrylate, ω-n-propyl polyethylene glycol- (poly) propylene glycol monomethacrylate, ω-iso-propyl polyethylene Glycol
(Poly) propylene glycol monoacrylate, ω-
iso-propyl polyethylene glycol- (poly) propylene glycol monomethacrylate, ω-n-butyl polyethylene glycol- (poly) propylene glycol monoacrylate, ω-n-butyl polyethylene glycol- (poly) propylene glycol monomethacrylate, ω-iso- Butyl polyethylene glycol-
(Poly) propylene glycol monoacrylate, ω-
iso-butyl polyethylene glycol- (poly) propylene glycol monomethacrylate, ω-tert-
Butyl polyethylene glycol- (poly) propylene glycol monoacrylate, ω-tert-butyl polyethylene glycol- (poly) propylene glycol monomethacrylate, ω-phenoxy polyethylene glycol- (poly) propylene glycol monoacrylate, ω-phenoxy polyethylene glycol- (poly )
Propylene glycol monomethacrylate, (poly) propylene glycol-polyethylene glycol monoacrylate, (poly) propylene glycol-polyethylene glycol monomethacrylate, ω-methoxy (poly) propylene glycol-polyethylene glycol monoacrylate, ω-methoxy (poly) propylene glycol- Polyethylene glycol monomethacrylate,
(Poly) butylene glycol-polyethylene glycol monoacrylate, (poly) butylene glycol-polyethylene glycol monomethacrylate, ω-methoxy (poly) butylene glycol-polyethylene glycol monoacrylate, ω-methoxy (poly) butylene glycol-polyethylene glycol monomethacrylate,
ω-methoxy (poly) ethylene glycol- (poly) propylene glycol-polyethylene glycol monoacrylate, ω-methoxy (poly) ethylene glycol-
(Poly) propylene glycol-polyethylene glycol monomethacrylate, ω-hexyloxy polyethylene glycol- (poly) propylene glycol mono (meth) acrylate, octadecyloxypolyethylene glycol-polypropylene glycol mono (meth) acrylate, ω-octylphenyl (poly) ethylene Examples thereof include glycol-polypropylene glycol mono (meth) acrylate, nonylphenyloxy (poly) ethylene glycol- (poly) propylene glycol-polyethylene glycol mono (meth) acrylate, polypropylene glycol-polyethylene glycol mono (meth) acrylate, and the like.

As a method for synthesizing the above-mentioned monomer, for example,
1) Methacrylic acid or acrylic acid in the presence of an alcal metal catalyst (sodium hydroxide, potassium hydroxide, etc.),
Method of sequentially adding alkylene oxide (ethylene oxide, propylene oxide, butylene oxide) at 50 to 200 ° C. and 1 to 10 atmospheres, 2) Alcohol or phenol having 1 to 4 carbon atoms in the presence of an alkali metal catalyst,
Polyether monool obtained by sequentially adding alkylene oxides (ethylene oxide, propylene oxide, butylene oxide) at 50 to 200 ° C. and 1 to 10 atm and methacrylic acid or acrylic acid is used as an acidic catalyst (sulfuric acid, paratoluenesulfonic acid, etc.). ) In the presence of
Examples thereof include a method of esterification at 00 ° C and 1 to 10 atm, or a reaction with an esterification reagent (such as dicyclohexylcarbodiimide) at -10 to 50 ° C and normal pressure.

In the present invention, the branched water-soluble polymer is
At least one selected from the above-mentioned branched polyvinyl alcohol and branched polyether can be used.

In the water-based ink of the present invention, the content of the branched water-soluble polymer is 0.005 to 20% by weight, preferably 1 to 10% by weight. If the amount is more than 20% by weight, the viscosity of the ink is increased and the thixotropy is exhibited, which is not preferable.

Next, the dye used in the ink of the present invention will be described. In the present invention, the dye may be any water-soluble dye, and examples thereof include direct dyes, acid dyes, basic dyes, and reactive dyes.

Specific examples of the dye include C.I. I Direc
t Black17, C.I. I. Direct Blac
k19, C.I. I. Direct Black 62, C.I.
I. Direct Black 154, C.I. I. Foo
d Black2, C.I. I. Reactive Bla
ck5, C.I. I. Acid Black 52, I.D. C.
I. Black dye such as Projet Fast Balck2,

C. I. Direct Yellow
l, C.I. I. Direct Yellow 44, C.I.
I. Direct Yellow86, C.I. I. Dir
ectYellow142, C.I. I. Direct Y
ellow330, C.I. I. Acid Yellow
3, C.I. I. Acid Yellow 38, C.I. I. B
asic Yellow11, C.I. I. Basic Y
ellow51, C.I. I. Disperse Yell
ow3, C.I. I. Disperse Yellow5,
C. I. Yellow dye such as Reactive Yellow2,

C. I. Direct Red227,
C. I. Direct Red23, C.I. I. Acid
Red18, C.I. I. Acid Red 52, C.I.
I. Basic Red 14, C.I. I. Basic R
ed39, C.I. I. Magenta dyes such as Disperse Red 60,

C. I. Direct Blue15,
C. I. Direct Blue 199, C.I. I. Di
rect Blue 168, C.I. I. Acid Blu
e9, C.I. I. Acid Blue 40, C.I. I. Ba
sic Blue 41, C.I. I. Acid Blue7
4, C.I. I. Reactive Blue 15, C.I.
I. Cyan dyes such as Disperse Blue 3 can be mentioned.

Other than these dyes, it is possible to use a dye having a reduced solubilizing group to enhance water resistance, a dye having a pH-sensitive solubility and a special grade, or the like. The concentration of the dye in the ink can be freely selected within the range of solubility and is usually 0.1 to 10% by weight, preferably 3 to 10% by weight for recording on cloth, metal (alumite), etc. Furthermore, when the recorded image needs to be shaded, 0.1 to 1
0% by weight is preferred.

The following moisturizers and dissolution agents are added to the ink of the present invention having the above-mentioned constitution in order to impart more inkjet suitability such as reliability, storage stability or ink permeability adjustment. You may contain an auxiliary agent.

Examples of such materials include 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol and 1,4-butane. Diol, 2,3, butanediol, 1,5-pentanediol, 1,7-heptanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, glycerin, diethylene glycol, tri ethylene glycol,
Tetraethylene glycol, polyethylene glycol 2
00, dipropylene glycol, 2,2′-thiodiethanol, 1,2,6-hexanetriol, and other alkylene glycols, monoethanolamine, diethanolamine, triethanolamine, and other alcohol amines, dimethylformamide, dimethylacetamide, Aprotic polar solvents such as dimethyl sulfoxide, sulfolane, 1,3-propane sultone, 1,2-dimethoxyethane, 1-2-diethoxyethane, 1,2-dibutoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol Dibutyl ether, 2-methoxyethanol, 2
-Ethoxyethanol, 2- (methoxymethoxy) ethanol, 2-butoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ethyl ether, 1-methoxy-2-propanol, 1-ethoxy-
Lower alkyl ethers of polyhydric alcohols such as 2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, formamide, 2-pyrrolidone, N-methyl-2-pyrrolidone , 1,3-dimethylimidazolidinone, sorbitol, sorbit, urea, 1,3-bis (β-hydroxyethyl) urea and the like. The content in these inks is preferably in the range of 1 to 40% by weight based on the total weight of the ink.

Further, when the ink of the present invention is used for ink jet recording, when an alkyl alcohol such as methanol, ethanol, propanol, 2-propanol, 1-butanol or 2-butanol is contained, the ejection property is improved, It is effective. These alcohols are preferably contained in the range of 1 to 10% of the total weight of the ink.

Further, if necessary, additives such as a surfactant, a rust preventive, a fungicide, an antioxidant and a pH adjuster may be contained.

As described above, the ink of the present invention is effective when used in ink jet recording. Ink jet recording methods include a recording method in which mechanical energy is applied to ink to eject droplets and a recording method in which thermal energy is applied to ink to eject droplets by bubbling the ink. The inventive inks are particularly suitable. Further, since a part of the polymer of the present invention has a part of its structure of alkylene oxide, it has an effect of reducing turbulent frictional resistance in a narrow tube like an ink flow path (Kazuo Murayama, Naka Naka, Mitsui, separate volume). "Chemical industry" vol.34,
p117 (1990)), a smooth ink supply is realized for recording such as ink jet recording having an ink flow path.

As the ink jet recording apparatus, firstly,
2, 3 and 4 show an example of a head configuration that is a main part of an apparatus utilizing thermal energy.

In FIG. 2, the head 1 is obtained by adhering a heating element substrate 3 to a glass, ceramic, silicon or plastic plate having a flow path (nozzle) 2 for passing ink. The heating element substrate 3 includes a protective layer 4 made of silicon oxide, silicon nitride, silicon carbide, etc., aluminum, gold, aluminum-copper alloy, aluminum-Si.
Electrode 5, HfB ₂ , TaN, TaA, etc.
1, a heat generating resistor layer 6 formed of a high melting point material such as poly-Si or TaSi, a heat storage layer 7 formed of thermally oxidized silicon, aluminum oxide or the like, and a material having a good heat dissipation property such as silicon, aluminum or aluminum nitride. Substrate 8 to be formed
Is made up of.

As an upper layer of the protective layer 4, Ta, N
By providing the corrosion-resistant metal layer 4a of b, Ni, Pt, Ir or the like, the effect of further improving the durability of the recording head can be obtained.

When a pulsed electric signal is applied to the electrode 5 of the head, the area indicated by h on the heating element substrate 3 rapidly generates heat, and bubbles are generated in the ink in contact with this surface. The generated pressure causes the meniscus 10 to project, and the ink is ejected through the nozzle 2 of the head, and the orifice 1
The recording small droplets 12 are formed from 1 and fly toward the recording material 13. FIG. 4 shows an external view of a multi-head in which a large number of the heads shown in FIG. 2 are arranged.

FIG. 2 is a sectional view of the head along the ink flow path, and FIG. 3 is a sectional view taken along line XY of FIG.

FIG. 5 shows an example of an ink jet recording apparatus incorporating this head. In FIG. 5, reference numeral 61 denotes a blade as a wiping member, one end of which is held and fixed by a blade holding member, and has a form of a cantilever. The blade 61 is arranged at a position adjacent to the recording area of the recording head, moves in a direction perpendicular to the moving direction of the recording head, contacts the ejection port surface, and caps. Furthermore, 63 is a blade 6
The ink absorber is provided adjacent to No. 1 and is held in the form of being ejected in the movement path of the recording head, like the blade 61. The blade 61, the cap 62, and the ink absorber 63 constitute an ejection recovery unit 64, and the blade 61 and the ink absorber 63 remove water, dust, and the like from the ejection port surface.

Reference numeral 65 has a discharge energy generating means,
A recording head 66 for ejecting ink to perform recording by ejecting ink to a recording material facing the ejection port surface provided with the ejection ports.
5 is a carriage for carrying the recording head 65 and moving the recording head 65. The carriage 66 slidably engages with a guide shaft 67, and a part of the carriage 66 is connected (not shown) to a belt 69 driven by a motor 68.
As a result, the carriage 66 can move along the guide shaft 67, and the recording head 65 can move the recording area and the area adjacent to the recording area. Reference numeral 51 is a paper feed section for inserting a recording material, and 52 is a paper feed roller driven by a motor (not shown). With these configurations, the recording material is fed to the position facing the ejection port surface of the recording head, and is ejected to the ejection section provided with the ejection roller 53 as the recording progresses.

In the above structure, when the recording head 65 finishes recording and returns to the home position, the head recovery unit 64.
The cap 62 is retracted from the moving path of the recording head 65, but the blade 61 is projected in the moving path.
As a result, the ejection port of the recording head 65 is wiped. When the cap 62 comes into contact with the ejection surface of the recording head 65 for capping, the cap 62 moves so as to project into the movement path of the recording head. When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are at the same positions as the positions at the time of wiping described above. As a result, the ejection opening surface of the recording head 65 is wiped even during this movement.

The above-mentioned movement of the recording head to the home position is performed not only at the end of recording and at the time of ejection recovery, but also at the home adjacent to the recording area at a predetermined interval while the recording head moves in the recording area for recording. The wiper is moved to the position, and the wiping is performed along with the move.

FIG. 6 is a vertical cross-sectional view showing an example of an ink cartridge that contains ink to be supplied to the recording head via an ink supply member, for example, a tube. 4 here
Reference numeral 5 is an ink cartridge, 40 is an ink containing portion for containing the supply ink, for example, an ink bag, and a rubber stopper 42 is provided at the tip thereof. By inserting a needle (not shown) into this stopper 42, the ink in the ink bag 40 can be supplied to the head. An ink absorber 44 receives the waste ink. As the ink container, it is preferable that the surface in contact with the ink is made of polyolefin, especially polyethylene.

The ink jet recording apparatus used in the present invention is not limited to the one in which the head and the ink cartridge are separately provided as described above, but may be one in which they are integrated as shown in FIG. It is preferably used. In FIG. 7, reference numeral 70 denotes a recording unit, in which an ink containing portion that contains ink, for example, an ink absorber is housed, and the ink in the ink absorber is discharged from a head portion 71 having a plurality of orifices. It is configured to be ejected as a droplet. It is preferable for the present invention to use polyurethane as the material of the ink absorber. Also,
Instead of using the ink absorber, a structure may be adopted in which the ink containing portion is an ink bag having a spring or the like inside. 72 is
It is an atmosphere communication port for communicating the inside of Cardridge with the atmosphere. The recording unit 70 is used in place of the recording head 65 shown in FIG.
It is removable with respect to.

Next, as a form of an ink jet recording apparatus utilizing the second mechanical energy, a nozzle forming substrate having a plurality of nozzles, a pressure generating element composed of a piezoelectric material and a conductive material arranged facing the nozzles. An on-demand ink jet recording head that includes ink that fills the circumference of the pressure generating element, and displaces the pressure generating element by an applied voltage to eject small droplets of the ink from a nozzle. FIG. 8 shows a configuration example of a recording head which is a main part of the recording apparatus.

The head has an ink flow path 80 communicating with an ink chamber (not shown), an orifice plate 81 for ejecting an ink droplet of a desired volume, a vibrating plate 82 for directly exerting a pressure on the ink, and The piezoelectric element 83 is joined to the vibration plate 82 and is displaced by an electric signal, and the piezoelectric element 83, the orifice plate 81, and the base body 84 for supporting and fixing the vibration plate 82 and the like.

In FIG. 8, the ink flow path 80 is formed of a photosensitive resin or the like, and the orifice plate 81 is formed by electroforming a metal such as stainless steel or nickel, forming a discharge port 85 by punching by press working, and vibrating. The plate 82 is formed of a metal film of stainless steel, nickel, titanium or the like, a high elastic resin film or the like, and the piezoelectric element 83 is formed of a dielectric material such as barium titanate or PZT.

In the recording head having the above-mentioned configuration, a pulse voltage is applied to the piezoelectric element 83 to generate strain stress, and the energy deforms the vibration plate bonded to the piezoelectric element 83, and the ink flow path 80 is formed. The ink in the inside is pressurized vertically and ink drops (not shown) are ejected from the orifice plate 85.
It operates so as to perform more ejection and recording.

Such a recording head is used by incorporating it in a recording device similar to that shown in FIG. The detailed operation of the recording apparatus is the same as that described above, and it does not matter.

[0064]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples. The composition ratio in the text is% by weight unless otherwise specified.

First, the preparation of various inks of the present invention will be described. The branched polymers used in this example were those shown in Table 1.

[0066]

[Table 1]

(Note) (1) Hydroxypropyl cellulose is Nippon Soda Co., Ltd.
Manufactured by HPC-S (2) ω-methoxy polyethylene glycol monomethacrylate polymer (20 mol of ethylene oxide added: molecular weight 5,000) is manufactured by Sanyo Kasei Co., Ltd. (3) Polyvinyl alcohol and polyethylene glycol are manufactured by Wako Pure Chemical Industries, Ltd. ), Reagent grade 1

The procedure for preparing the ink is as follows, in which ion-exchanged water aqueous solutions of the branched polymer having an appropriate concentration (5 to 10%) are prepared in advance.

Examples 1 to 5 (black ink) Ion-exchanged water, a solvent, an aqueous dye solution and, if necessary, a surfactant were added to the aqueous polymer solution in this order with stirring to prepare each composition at a predetermined concentration. . After stirring for 3 hours, the mixture was filtered through a membrane filter having a pore size of 0.45 μm to prepare black inks of Examples 1 to 5 of the invention. The composition of the ink is shown in Table 2.

[0070]

[Table 2]

Comparative Examples 1 and 2 (Black Ink) As Comparative Example, the same as Example 1 except that 5.0% of polyethylene glycol 300 (degree of polymerization 300) was used instead of the branched water-soluble polymer. An ink having the same composition as in Example 2 was prepared as Comparative Example 1 except that 5% of polyvinyl alcohol (polymerization degree: 500) was used in place of the branched water-soluble polymer, as Comparative Example 1, respectively.

The inks of Examples 1 to 7 and Comparative Examples 1 to 2 listed above were evaluated for ink performance.

The performance evaluation items for ink jet recording are 1. Optical density (OD value), 2. Feathering, 3.
Discharge stability, 4. There are four items of ejection response. Both evaluations were performed in a constant temperature test room at a temperature of 23 ° C. and a humidity of 60%.

1. Optical Density (OD Value) A pattern having 5 square 5 mm square solid portions is printed on an A4 size paper, and the optical density of the print sample after 30 minutes or more is measured. Macbeth reflection densitometer R
The measurement was performed at D914, and the average value was used as the OD value. The amount of ink applied to the solid portion is 12 nl / mm ² .

2. Feathering A4 size paper was recorded with dots thinned out every other nozzle of the recording head, and dots of a print sample after 30 minutes or more were observed with a magnifying glass and evaluated according to the following 5 grades.

5: True circle dots 4: Dots with bleeding or deformation on 1/4 of the circumference 3: Dots with bleeding or deformation on 1/2 of the circumference 2: Circles Dots with bleeding or deformation on 3/4 of the circumference 1: Dots without any arc

3. Ejection stability The letters and numbers are continuously recorded, the recorded dots are observed, and the amount of occurrence of missing recorded dots is measured.
Graded.

◯: Dot missing within 10 times during recording of 500 sheets of A4 paper Δ: Within 20 missing dots during recording of 500 sheets of A4 paper ×: 20 missing dots or more during recording of 500 sheets of A4 paper

4. Ejection response Record dots are recorded with pulse signals of driving frequencies 2 kHz and 10 kHz, 50 lines each, and dot dropouts in the recording lines are observed. At 2 kHz and 10 kHz
The ratio of the number of missing dots in the case of z (= 10 kHz / 2 kHz)
z) was calculated and classified into the following three stages.

◯: Ratio of 0.9 or more to 1.0 Δ: Ratio of 0.7 to less than 0.9 ×: Ratio of less than 0.7

[Evaluator] BJC60 manufactured by Canon Inc. as a recording apparatus for evaluating the ink jet recordings 1 to 4 above.
0 (360 dpi) was used. The ink was supplied by using a method of filling the intended ink in a dedicated ink container. The evaluation of the corresponding comparative ink was also performed under the same conditions as for recording with the ink of the example. NP-SK paper for electrophotography (Lot as a paper for evaluation of evaluation items 1 to 4)
No. OKK10) was used.

[Evaluation Results] Table 3 shows the performance evaluation results of the ink of the present invention using BJC600. In addition, Table 3 shows the results of the same evaluation of the ink of Comparative Example.

[0083]

[Table 3]

From the results shown in Table 3, the water-based ink of the present invention is prevented from lowering OD due to bronze and exhibits a high OD. Further, the feathering is equal to or higher than that of the conventional ink, and the effect of improving the ejection stability and the ejection response is recognized.

[0085]

As described above, according to the water-based ink of the present invention, the bronzing phenomenon is prevented, a high optical density is obtained, and the feathering is equal to or higher than that of the conventional ink, and the ejection stability, The effect of improving the ejection response is recognized.

In particular, the ink of the present invention has effects such as high color development, feathering prevention, and excellent dischargeability in recording on plain office paper such as electrophotographic paper. Since the ink of the present invention is essentially characterized by eliminating bronze, the surface of the recording material can be applied to various recording materials other than plain paper such as transparency films, cloths, metal plates, etc. It is useful because it is not affected by pH and unevenness.

In the ink jet recording method and recording apparatus of the present invention, the above effects can be remarkably obtained by using the above water-based ink.

[Brief description of drawings]

FIG. 1 is an X-ray diffraction pattern of dyes in an ink of the present invention and a conventional example.

FIG. 2 is a vertical cross-sectional view of a head portion of an inkjet recording device.

FIG. 3 is a cross-sectional view of a head portion of the inkjet recording device.

FIG. 4 is an explanatory diagram showing an example of a head having a plurality of nozzles of an inkjet recording apparatus.

FIG. 5 is a perspective view showing an example of an inkjet recording apparatus.

FIG. 6 is a vertical cross-sectional view showing an example of an ink cartridge.

FIG. 7 is a perspective view of a specification in which an inkjet recording head and an ink cartridge are integrated.

FIG. 8 is a vertical cross-sectional view of an inkjet recording head using a piezoelectric element.

FIG. 9 is a diagram showing a structure of a branched polyvinyl alcohol of the ink (b) of the present invention.

[Explanation of symbols]

 1 Head 2 Flow Path (Nozzle) 3 Heating Element Substrate 4 Protective Layer 5 Electrode 6 Heating Resistor Layer 7 Heat Storage Layer 8 Substrate 10 Meniscus 11 Orifice 12 Recording Small Droplet 13 Recording Material 51 Paper Feeding Section 52 Paper Feeding Roller 53 Discharging Paper roller 61 Blade 62 Cap 63 Ink absorber 64 Head recovery unit 65 Ink jet recording head 66 Carriage 67 Carriage guide shaft 68 Carriage drive unit (motor) 69 Drive belt unit

Claims (10)

[Claims] 1. A water-based ink containing a color material and a liquid medium, which contains a branched water-soluble polymer. 2. The aqueous ink according to claim 1, wherein the branched water-soluble polymer is at least one selected from branched polyvinyl alcohol and branched polyether. 3. The content of the branched water-soluble polymer is 0.
The water-based ink according to claim 1, which is 005 to 20% by weight. 4. The water-based ink according to claim 1, wherein the coloring material is a dye. 5. The content of the dye is 0.1 to 10% by weight.
The water-based ink according to claim 1, which is 6. An inkjet recording method for recording on a recording material by ejecting ink droplets containing a color material and a liquid medium from an orifice of a recording head according to a recording signal, wherein the ink is recorded. 6. An inkjet recording method for recording using the water-based ink according to any one of 5 above. 7. The ink jet recording method according to claim 6, wherein recording is performed by causing thermal energy to act on the ink to eject droplets. 8. The ink jet recording method according to claim 6, wherein recording is performed by causing mechanical energy to act on the ink to eject droplets. 9. A water-based ink according to claim 1, wherein the ink is a recording unit including an ink containing portion containing ink and a recording head portion for ejecting the ink as ink droplets. Is a recording unit. 10. An ink jet recording apparatus having a recording unit having an ink containing section containing ink and a recording head section for ejecting ink as ink droplets, wherein the recording unit used in the apparatus is an ink jet recording apparatus. An inkjet recording device that is a recording unit.