JP2675897B2 - Ink and ink jet recording method using the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ink particularly suitable for an ink jet printer, and further, an ink is ejected from an orifice of a recording head by the action of thermal energy, so-called uncoated paper, so-called. The present invention relates to an ink jet recording method for recording on plain paper.

[Conventional technology]

The ink jet recording method has an advantage that a high-resolution recorded image can be obtained at a high speed by using a highly integrated head with little noise during recording.

In such an ink jet recording method, as an ink, one obtained by dissolving various water-soluble dyes in water or a mixed liquid of water and an organic solvent is used.

However, when a water-soluble dye is used, these water-soluble dyes are originally inferior in light resistance, so that the light resistance of a recorded image often becomes a problem.

Further, since the ink is water-soluble, the water resistance of the recorded image often becomes a problem. That is, rain on the recorded image,
If sweat or water for eating or drinking is applied, the recorded image may be blurred or disappear.

On the other hand, stationery using a dye such as a ballpoint pen has the same problem, and various aqueous pigment inks for stationery have been proposed to solve the problems of light fastness and water resistance. As practical examples of water-based pigment inks, dispersion stability, prevention of ink solidification at the pen tip, and prevention of abrasion of balls of ball-point pens are examined as examples. JP-A-58-80368 and JP-A-61-200182 JP-A-61-247774, JP-A-61-272278, JP-A-62-568, JP-A-62.
-101671, 101672, JP-A-1-249869, 1-3017
No. 60 bulletin etc. can be mentioned. Recently, ballpoint pens and markers using water-based pigment ink have come on the market as products.

[Problems to be solved by the invention]

However, when the conventional water-based pigment ink for stationery is used in an ink jet recording apparatus of the type in which recording liquid is jetted by the action of heat energy from the orifice of the recording head to perform recording, a remarkable obstacle is caused in ejection stability and printing failure. There was a drawback that occurs. In particular, when a conventional pigment ink is used when recording is performed by applying thermal energy and ejecting droplets, when heat is applied to the ink, a pulse is applied to the ink to form a deposit on the thin film resistor. There is a case in which non-ejection occurs because the foaming is incomplete and the ejection of the droplet cannot respond to the applied pulse. That is,
In order to stably eject the ink from the tip of the nozzle, the ink should be foamed in a desired volume on the thin film resistor, and further, it must have the ability to repeat foaming and defoaming at a desired time. However, since the conventional stationery inks do not satisfy these performances, when the ink jet recording apparatus is filled and recording is performed, the above-described various inconveniences occur.

Also, when using a dispersion system called pigment ink for ink jet recording, preventing solidification at the head of the head by leaving it for a long time is an important technical issue, and the composition of the ink is important in designing a reliable pigment ink. That's the point.

Furthermore, among the conventional water-based pigment inks, although the ejection property is excellent in a relatively short time, the ejection becomes unstable when the driving conditions of the recording head are changed or when the continuous ejection is performed for a long time, Finally, there is a problem that ejection is stopped.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide an ink in which the solidification of the pigment ink at the tip of the head due to leaving for a long time is eliminated.

Another object of the present invention is to provide an ink that can always perform stable ejection even when the driving conditions change or when it is used for a long time.

Still another object of the present invention is to provide an ink jet recording method capable of constantly stable high-speed recording and obtaining a recorded image excellent in fastness such as water resistance and light resistance when printed on non-coated paper. It is in.

[Means and actions for solving the problems]

 The above object is achieved by the present invention described below.

That is, the present invention is an ink characterized in that it contains a pigment, a water-soluble resin, and a compound represented by the following general formula (I) in an aqueous medium. Is an ink jet recording method in which recording is performed by ejecting ink as droplets from the fine holes by applying.

(However, l, m, n represents 0 or a positive integer satisfying the relation of 1 ≦ l + m + n ≦ 25.) Hereinafter, the present invention will be described in detail.

The inventors of the present invention have made diligent studies on a method of increasing the resolubility of the solidified ink in order to prevent the ink from solidifying at the tip of the recording head and causing various problems in the aqueous pigment ink. The present invention has been completed by discovering that the ink which has solidified by drying when the compound represented by the structural formula is contained can be redissolved by the ink itself and various problems at the head end can be solved.

Aqueous pigment inks generally agglomerate when dried and, unlike inks using dye inks, cannot be easily redissolved. In order to redissolve this, it must be redispersed in a highly alkaline solution using ultrasonic waves or the like. On the other hand, the solidification of the ink at the tip of the head increases the airtightness of the cap, and can be improved to some extent by periodically cleaning the face surface of the head with a wiper or the like.

However, it is not a preferable solution to provide a cleaning means with a high alkali in the apparatus because it leads to a cost increase, and a high alkali is dangerous to the user of the printer when it is touched by the hand.

Therefore, the inventors of the present invention have studied means for improving the resolubility of the solidified ink by improving the constituent elements of the ink. As a result, the resolubility of the ink can be improved by incorporating the above compound into the ink. Have been found to be significantly improved.

In the ink adhering to the face surface of the head, water and low-boiling point solvent contained in the ink evaporate quickly, leaving the pigment dispersion and the high-boiling point solvent. It was found that the ink solids formed at this time included a film that could be formed and a film that could not be formed, depending on the difference in ink composition, and this was related to the hygroscopicity of the remaining solvent. That is, in an ink using a solvent having a high hygroscopic property, a film is hard to be formed when dried, and this solid substance can be redissolved by the ink itself relatively easily, and on the contrary, contains a solvent which is not so. The ink forms a film that is difficult to redissolve. It is not clear why the compound having the above general formula used in the present invention is excellent in hygroscopicity, but it is considered that it has a strong ability to take in water because it has many hydroxyl groups in its structure. Furthermore, since these compounds reduce the viscosity by introducing an ethylene oxide chain, they have particularly preferable properties as a solvent for an ink for ink jet.

Preferred specific examples of the compound represented by the above general formula are shown below.

Among these compounds, the compounds No. 1 to No. 8 are preferable for the present invention in terms of preventing the pigment ink from sticking.

As a method of preparing the above compound, a predetermined amount of polyhydric alcohol and catalyst NaOH or KOH are put in a pressure resistant glass container, and the inside is replaced with nitrogen through a supply pipe. next,
The temperature of the reaction solution is raised from 110 ° C. to 130 ° C. with stirring, and a predetermined amount of ethylene oxide gas is gradually introduced. Stir for several hours at that temperature. After completion of the reaction, in order to remove the residual NaOH or KOH in the unreacted liquid, the reaction liquid is passed under pressure through a filter paper laminated with diatomaceous earth to obtain the desired product. (When the viscosity is high, it is made into an aqueous solution and filtered under heat and pressure.) The content of such a compound in the ink is 0.5 to 30% by weight, preferably 5 to 20% by weight. When this amount is less than 0.5% by weight, there is no effect in preventing solidification of the ink at the head end of the ink, and when this amount exceeds 30% by weight, the viscosity of the ink becomes too high.

The amount of the pigment used in the present invention is 3 to 20% by weight,
It is preferably used in the range of 3 to 12% by weight.

As the pigment used in the present invention, any pigment can be used as long as it satisfies the above performance.For example, as a black pigment, No. 2300, No. 900, MCF88, No. 33, No.
40, No.45, No.52, MA7, MA8, # 2200B (Made by Mitsubishi Kasei), RAVEN1255 (Colombia), REGAL400R, REGAL3
30R, REGAL660R, MOGUL L (above made by KYABOT), Color
Black FW1, COLOR Black FW18, Color Black S170, Co
lor Black S150, Printex 35, Printex U (degutsa)
It is also possible to use carbon blacks such as those mentioned above, as well as those newly manufactured for this purpose.

In the present invention, the water-soluble resin contained as a dispersant for the pigment is preferably soluble in an aqueous solution in which an amine is dissolved and has a weight average molecular weight in the range of 3,000 to 30,000. Further, preferably, anything in the range of 5000 to 15000 can be used, and styrene-acrylic acid copolymer, styrene-acrylic acid-acrylic acid alkyl ester copolymer, styrene-maleic acid copolymer, Styrene-maleic acid-acrylic acid alkyl ester copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-maleic acid half ester copolymer, vinylnaphthalene-acrylic acid copolymer Examples thereof include polymers, vinylnaphthalene-maleic acid copolymers, and salts thereof. The water-soluble resin is contained in the recording liquid in an amount of 0.1 to 5% by weight, preferably 0.3 to 2% by weight.

Further, in the ink of the present invention, preferably the entire ink is adjusted to be neutral or alkaline so that the solubility of the water-soluble resin is improved and the recording liquid has further excellent long-term storage stability. It is possible because it is possible. However, in this case, it may cause corrosion of various members used in the ink jet recording apparatus.
It is desirable that the pH range is set to.

Examples of the pH adjuster include various organic amines such as diethanolamine and triethanolamine, inorganic alkali agents such as sodium hydroxide, lithium hydroxide and alkali metal aquatic products such as potassium hydroxide, organic acids and mineral acids. can give. As described above, the carbon black and the water-soluble resin are dispersed or dissolved in the water-soluble medium.

A suitable aqueous medium in the ink of the present invention is a mixed solvent of water and a water-soluble organic solvent. As water, not ordinary water containing various ions but ion-exchanged water (deionized water) is used. Is preferred.

In addition, as the water-soluble solvent component used by mixing with any water that can be used in combination, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol tert. -Alkyl alcohols having 1 to 4 carbon atoms such as butyl alcohol and isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketones or keto alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyethylene Polyalkylene glycols such as glycol and polypropylene glycol; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, Hexylene glycol, alkylene glycols the alkylene group contains 2-6 carbon atoms and diethylene glycol; glycerin, ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether,
Lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether; N
-Methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like can be mentioned. Among these many water-soluble organic solvents, polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether are preferable.

Among these many water-soluble organic solvents, organic amine water is contained in the ink of the present invention as an essential component, preferably 0.001 to 10% by weight of the total ink.

Furthermore, it has been found that it is effective to add an aliphatic monohydric alcohol such as ethanol or isopropyl alcohol in an amount of 3% by weight to 15% by weight in order to obtain ejection stability. It is considered that this is because the addition of these solvents makes it possible to more stably foam the ink on the thin film resistor. However, if these solvents are added excessively, the print quality of the printed matter will be impaired, so a more suitable concentration of these solvents is in the range of 3 to 10% by weight. Furthermore, as an effect of these solvents, by adding these solvents to the dispersion,
It is possible to suppress the generation of bubbles during dispersion and perform efficient dispersion.

The content of the water-soluble organic solvent in the ink of the present invention,
3 to 50% by weight of the total weight of the ink, preferably 3 to 40% by weight
The total amount of water used is 10 to 90% by weight, preferably 30 to 80% by weight.

In addition to the above components, the ink of the present invention may further contain a surfactant, a defoaming agent, an antiseptic agent, etc. in order to obtain a recording liquid having desired physical properties, if necessary. ,
A commercially available water-soluble dye or the like can be added.

As the surfactant, fatty acid salts, higher alcohol sulfate ester salts, liquid fatty acid sulfate ester salts, anionic surfactants such as alkylallyl sulfonic acid, polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, polyoxyethylene There are nonionic surfactants such as sorbitan alkyl esters, and one or more of these can be appropriately selected and used. The amount used depends on the dispersant, but is 0.01 with respect to the total amount of ink.
To 5% by weight is desirable. At this time, the surface tension of the ink is
It is preferable to determine the amount of the activator to be added so as to be 30 dyne / cm or more. This is because the surface tension of the ink having a value smaller than this causes an undesirable situation such as printing deviation (deviation of ink droplet landing point) due to wetting of the nozzle tip in the recording method of the present invention. Is. On the other hand, a water-soluble organic solvent, a pH adjusting agent, an antifoaming agent, an antiseptic agent, etc. can be added in order to obtain an ink having desired physical properties. Further, it is possible to add a commercially available water-soluble dye or the like.

Generally, the properties required for ink jet inks include physical properties such as ink viscosity, surface tension, and pH.However, in a dispersion system such as an aqueous pigment ink, even if these physical properties are satisfied, the ink foams. Was often unstable.

Therefore, the present inventors are thermally stable with the aqueous pigment ink,
Further, as a result of earnest research on the performance of the ink capable of optimal foaming, the amount of the water-soluble resin dissolved in the ink is 2% or less of the total weight of the ink, and preferably 1% or less. It was found that the ink accurately foams even under various driving conditions, and further, does not generate a deposit on the thin film resistor even for a long period of time. In other words, if a large amount of excess water-soluble resin relative to the pigment is present in the ink, the ink will not foam even if given thermal energy is applied on the thin film resistor, or these excesses will be generated due to the heat applied during pulse application. The water-soluble resin of 1) becomes an insoluble substance and is deposited on the thin film resistor, which causes ejection failure and print disorder.

The dissolved water-soluble resin refers to a resin that is not adsorbed to the pigment in the ink but is dissolved in the liquid medium.

One means for reducing the amount of the dissolved water-soluble resin is to adjust the weight ratio of the pigment and the water-soluble resin in the range of 3: 1 to 10: 1, preferably 10: 3 to 10: 1 when the ink is prepared. Is to adjust.

Further, the total amount of the pigment and the water-soluble resin in the dispersion liquid is preferably 10% or more, and more preferably 30% or less on a weight basis. The reason is that if the pigment and the water-soluble resin having a certain concentration or more do not exist in the dispersion liquid, the dispersion can be efficiently performed and the optimum dispersion state cannot be obtained.

As a method for preparing the recording liquid of the present invention, first, a pigment is added to an aqueous solution containing at least a dispersion resin, an amine and water, stirred, and then dispersed using a dispersing means described later, and if necessary, centrifuged. Separation treatment is performed to obtain a desired dispersion liquid. Next, the above-mentioned components are added to this dispersion, and the mixture is stirred to form a recording liquid.

In particular, in order to reduce the amount of unadsorbed resin to 2% or less, an aqueous solution containing resin, amine and water is added in the production method to 60%.
It is necessary to completely dissolve the resin in advance by stirring for 30 minutes or more at ℃ or more.

Further, it is necessary to add 1.2 times or more of the amount of amine that dissolves the resin, to the amount of amine calculated by the acid value of the resin. The amount of this amine is calculated by the following formula.

Furthermore, it is also necessary to perform premixing for 30 minutes or more before dispersing the aqueous solution containing the pigment.

This premixing operation improves the wettability of the pigment surface and promotes the adsorption of the resin to the pigment surface.

As amines added to the dispersion, organic amines such as monoethanolamine, diethanolamine, triethanolamine, aminomethylpropanol, and ammonia are preferable.

On the other hand, the disperser used in the present invention may be any disperser generally used, and examples thereof include a ball mill, a roll mill and a sand mill.

Among them, a high speed type sand mill is preferable, for example, a super mill, a sand grinder, a bead mill,
Agitator mills, Glen mills, Dyno mills, Pearl mills, Cobol mills (all are trade names) and the like.

In the present invention, as a method of obtaining a pigment having a desired particle size distribution, the size of the pulverized media of the disperser is reduced, the filling rate of the pulverized media is increased, the treatment time is lengthened, and the discharge speed is slowed. After crushing, a method such as classification with a filter or a centrifugal separator is used.
Alternatively, a combination of these techniques may be used.

In addition, as a method of measuring the amount of the non-adsorbed resin according to the present invention, the pigment component and the resin component adsorbed on the pigment are precipitated using an ultracentrifuge or the like, and the residual resin content contained in the supernatant liquid is determined. TOC (Total Organic Carbon, total organic carbon meter) or gravimetric method (method of evaporating the supernatant to dryness and measuring the amount of resin)
Etc. are preferably used.

The recording liquid of the present invention is particularly suitable for use in an ink jet recording method in which droplets are ejected by the action of heat energy for recording, but it goes without saying that it can also be used for general writing instruments.

A recording apparatus suitable for recording using the ink of the present invention is an apparatus which applies thermal energy corresponding to a recording signal to a recording liquid in a chamber of a recording head and generates a droplet by the energy.

The head configuration example, which is the main part, is shown in FIG.
This is shown in FIG. 2B and FIG.

The head 13 is a glass having a groove 14 through which ink passes, a ceramics plate, a plastic plate, or the like, and a heating head 15 (thin film head is shown in the figure, but is not limited thereto) used for thermal recording. It is obtained by bonding.
The heating head 15 is a protective film 16 formed of silicon oxide or the like.
It is composed of aluminum electrodes 17-1 and 17-2, a heating resistor layer 18 made of nichrome, a heat storage layer 19, and a substrate 20 having a good heat dissipation property such as alumina.

The ink 21 reaches the discharge orifice (fine holes) 22 and forms a meniscus 23 by the pressure P.

Now, when an electric signal is applied to the electrodes 17-1 and 17-2, the area indicated by n of the heating head 15 generates heat rapidly, and bubbles are generated in the ink 21 in contact with the area, and the meniscus is generated by the pressure.
23 protrudes, the ink 21 is ejected, and becomes a recording droplet 24 from the orifice 22, and flies toward the recording medium 25. FIG. 2 is an external view of a multi-head in which a number of heads shown in FIG. 1 (a) are arranged. The multi-head is made by bonding a glass plate 27 having multi-grooves 26 and a heat-generating head 28 similar to that described in FIG. 1 (a).

It should be noted that FIG. 1A shows a head 13 along the ink flow path.
FIG. 1 (b) is a cross-sectional view of FIG.
It is a cutting plane along a line.

FIG. 3 shows an example of an ink jet recording apparatus incorporating the head according to FIG.

In FIG. 3, reference numeral 61 denotes a blade as a wiping member, one end of which is held by a blade holding member to become a fixed end, which is in the form of a cantilever. blade
Reference numeral 61 is arranged at a position adjacent to the recording area of the recording head, and in the case of this example, it is held in a protruding form in the moving path of the recording head. 62 is a cap and blade
It is provided in a home position adjacent to 61, and is configured to move in a direction perpendicular to the moving direction of the recording head and come into contact with the ejection port surface to perform capping. Further 63 is blade 61
Is an ink absorber provided adjacent to the blade 61.
Similarly to the above, the recording head is held in a protruding form in the moving path of the recording head. The blade 61, the cap 62, and the absorbent body 63 constitute a discharge recovery section 64, and the blade 61 and the absorbent body 63.
Thus, water, dust, etc. on the surface of the ink ejection port are removed.

Reference numeral 65 denotes a recording head which has ejection energy generating means and discharges ink on a recording material facing the ejection port surface where the ejection ports are arranged to perform recording, and 66 denotes a mounting of the recording head 65 and movement of the recording head 65. Carriage for doing. Carriage
66 is slidably engaged 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 thereto.

Reference numeral 51 is a paper feed unit 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 a position facing the discharge port surface of the recording head, and as the recording progresses, a discharge roller 53 is formed.
Is discharged to the paper discharge unit where.

In the above configuration, when the recording head 65 returns to the home position at the end of recording or the like, the cap 62 of the head recovery unit 64 is retracted from the moving path of the recording head 65,
61 protrudes into the movement route. As a result, the recording head
The ejection port surface of 65 is wiped. When the cap 62 comes into contact with the ejection surface of the recording head 65 to perform the capping, the cap 62 moves so as to project into the moving 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 in the same position as the above wiping position. As a result, even during this movement, the ejection port surface of the recording head 65 is wiped.

To move the recording head to the home position described above,
Not only at the end of recording or at the time of ejection recovery, while the recording head moves in the recording area for recording, it moves to the home position adjacent to the recording area at a predetermined interval, and the wiping is performed along with this movement. Be seen.

FIG. 4 is a diagram showing an example of an ink cartridge containing ink supplied to the head through the ink supply tube. Here, reference numeral 40 denotes an ink bag storing the supply ink, and a rubber stopper 42 is provided at the tip of the ink bag. By inserting a needle (not shown) into the stopper 42, the ink in the ink bag 40 can be supplied to the head. 44
Is an ink absorber for receiving waste ink.

The ink jet recording apparatus used in the present invention is not limited to the above-described head and ink cartridge which are separate bodies, and an integrated one as shown in FIG. 5 is also preferably used. .

In FIG. 5, reference numeral 70 denotes an ink jet cartridge, which contains an ink absorber impregnated with ink, and which receives ink from a head portion 71 having a plurality of orifices. It is configured to be ejected as ink droplets.

Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the cartridge with the atmosphere.

The ink jet cartridge 70 is used in place of the recording head 65 shown in FIG. 3, and is attachable to and detachable from the carriage 66.

 Next, the present invention will be described specifically with reference to examples.

〔Example〕

Example 1 (Preparation of pigment dispersion liquid) Styrene-acrylic acid-butyl acrylate copolymer (acid value 116, weight average molecular weight 3700) 2 parts Monoethanolamine 1 part Ion-exchanged water 73 parts Diethylene glycol 5 parts The above components are mixed. Then, heat at 70 ℃ in a water bath,
Dissolve the resin completely. To this solution, 14 parts of a newly produced carbon black (manufactured by MCF88 Mitsubishi Kasei) and 5 parts of isopropyl alcohol were added, premixed for 30 minutes, and then dispersed under the following conditions.

Dispersing machine Sand grinder (Igarashi Machinery Co., Ltd.) Grinding media Zirconium beads 1mm diameter Packing ratio of grinding media 50% (volume) Grinding time 3 hours Centrifugation treatment (12000RPM, 20 minutes) is performed to remove coarse particles and dispersion liquid. And

(Preparation of Ink) 30 parts of the above-mentioned dispersion liquid Compound (1) 10 parts N-methyl 2-pyrrolidone 5 parts Isopropyl alcohol 5 parts Ion-exchanged water 50 parts The above components are mixed and the pH is adjusted from 8 with monoethanolamine. It was adjusted to be 10 and used as ink (A).

Example 2 (Preparation of Pigment Dispersion) Styrene-acrylic acid-butyl acrylate copolymer (acid value 120, weight average molecular weight 6100) 5 parts Triethanolamine 2 parts Ion-exchanged water 66 parts Diethylene glycol 5 parts Mix the above components Then, heat to 70 ° C with a water bath,
Dissolve the resin completely. To this solution, 15 parts of newly produced MOGUL L (manufactured by KYABOT) and 7 parts of ethanol were added, and after premixing for 30 minutes, dispersion treatment was performed under the following conditions.

Disperser Pearl Mill (manufactured by Ashizawa) Grinding media Glass beads 1 mm diameter Filling ratio of grinding media 50% (volume) Discharge rate 100 ml / min. Centrifugation treatment (12000 RPM, 20 minutes) is performed to remove coarse particles and dispersion liquid. And

(Preparation of ink) 30 parts of the above dispersion compound (2) 10 parts of 1,3-dimethyl-2-imidazolidinone 10 parts of ethanol 5 parts of ion-exchanged water 45 parts The above components are mixed to adjust the pH to triethanol. It was adjusted to 8 to 10 with amine and used as ink (B).

Example 3 (Preparation of Pigment Dispersion) Styrene-acrylic acid-ethyl acrylate copolymer (acid value 138, weight average molecular weight 5600) 4 parts Aminomethyl propanol 2 parts Ion-exchanged water 69 parts Diethylene glycol 5 parts Mix the above components Then, heat to 70 ° C with a water bath,
Dissolve the resin completely. To this solution, 15 parts of carbon black (MCF88, manufactured by Mitsubishi Kasei) and 5 parts of ethanol were added, and after premixing for 30 minutes, dispersion treatment was carried out under the following conditions.

Disperser Pearl Mill (manufactured by Ashizawa) Grinding media Glass beads 1 mm diameter Filling ratio of grinding media 50% (volume) Discharge rate 100 ml / min. Centrifugation treatment (12000 RPM, 20 minutes) is performed to remove coarse particles and dispersion liquid. And

(Preparation of ink) 50 parts of the above-mentioned dispersion compound (3) 15 parts of ethylene glycol 5 parts of ethanol 5 parts of ion-exchanged water 25 parts of the above components are mixed to adjust the pH to 8 to 10 aminomethyl propanol To prepare ink (C).

Example 4 An ink was prepared by using the compound (4) exemplified in the specification instead of the compound (1) exemplified in the specification in the ink of Example 1, and was designated as an ink (D).

Example 5 Ink (E) was prepared by using the compound (5) illustrated in the specification instead of the compound (2) illustrated in the specification in the ink of Example 2.

Example 6 An ink was prepared by using the compound (6) exemplified in the specification in place of the compound (3) exemplified in the specification in the ink of Example 3, and was designated as an ink (F).

Comparative Example 1 Ink (G) was prepared in the same manner as in Example 1 except that the compound (1) was changed to diethylene glycol monobutyl ether.

Comparative Example 2 Ink (H) was obtained by preparing an ink with the same formulation by replacing the compound (2) contained in the dispersion liquid of Comparative Example 2 with ethylene glycol monobutyl ether.

The following tests were conducted using an ink jet recording apparatus having an on-demand type multi-recording head that ejects ink by applying thermal energy according to a recording signal using each of the above inks. The result is
It is shown in the table.

T1: Drive condition and ejection stability Set the drive voltage to 25V, and the frequency of each voltage is 2KHz, 4
Printing was performed at room temperature under two conditions of KHz, and the presence or absence of print disturbance, chipping, non-ejection, etc. was observed to evaluate the ejection stability.

A: Discharges cleanly from the first character, during continuous printing, no discharge,
There is no chipping or printing disorder.

B: The character portion was ejected cleanly, but several ejection failures occurred in the solid print portion.

C: Even in the character portion, when several characters are printed, ejection failure occurs, and the characters are disturbed so that the characters cannot be read.

T2: Clogging during reprinting after pausing printing For reprinting clogging after pausing printing, fill the printer with the specified ink, print alphanumeric characters continuously for 10 minutes, and then stop printing. After leaving it for 30 minutes at room temperature without capping, alphanumeric characters were printed again, and it was judged by the presence or absence of defective parts such as faintness and chipping of characters.

A: There is no defect from the first letter.

B: Part of the first letter is faint or sloppy.

C: The first character cannot be printed at all.

T3: Recovery from clogging when reprinting after long-term stop of printing After printing the specified ink on the printer for 10 minutes continuously with alphanumeric characters, the printer is stopped and the printer is stopped at 60 ° C for 10 days. After leaving it to stand, the nozzle clogging recovery operation was performed, and it was determined how many times it was possible to perform normal printing without character blurring or chipping.

A: Normal printing is possible with normal operation after 1 to 5 recovery operations.

B: Normal printing is possible with 6 to 10 recovery operations.

C: Normal printing is possible with 11 or more recovery operations.

T0: Amount of dissolved water-soluble resin The ink obtained was ultra-high-speed cooled centrifuge (manufactured by Beckmann)
At 55000 rpm for 5 hours, the pigment component and the resin component adsorbed to the pigment are allowed to settle, and a fixed amount of the supernatant is collected,
Dry and solidify in a vacuum dryer (60 ° C, 24 hours). The percentage of the amount of the resin to the charged ink is calculated and defined as the residual resin concentration.

[Effect] As described above, the ink of the present invention, when applied to an ink jet printer, does not cause solidification of the ink at the head of the head even after being left for a long time, and it is of course excellent in the robustness of the printed matter. In addition, the density of the printed matter is high, and stable ejection can be always performed even when the driving condition is changed or the printer is used for a long time, and the reliability is excellent.

[Brief description of the drawings]

1 (a) and 1 (b) are a longitudinal sectional view and a transverse sectional view of a head portion of an ink jet recording apparatus. FIG. 2 is an external perspective view of a head obtained by multiplying the head shown in FIG. FIG. 3 is a perspective view showing an example of the ink jet recording apparatus. FIG. 4 is a longitudinal sectional view of the ink cartridge. FIG. 5 is a perspective view of an ink jet cartridge. 61 ...... Wiping member 62 ...... Cap 63 ...... Ink absorber 64 ...... Ejection recovery section 65 ...... Recording head 66 ...... Carriage

Claims (11)

(57) [Claims] 1. An ink comprising a pigment, a water-soluble resin, and a compound represented by the following general formula (I) in an aqueous medium. (However, l, m, n represents 0 or a positive integer satisfying the relation of 1 ≦ l + m + n ≦ 25) 2. The ink according to claim 1, wherein the amount of the water-soluble resin dissolved in the ink is 2% by weight or less. 3. The ink according to claim 1, wherein the aqueous medium contains water and a water-soluble organic solvent. 4. The ink according to claim 3, wherein the water-soluble organic solvent contains a polyhydric alcohol and / or its alkyl ether and an aliphatic monohydric alcohol. 5. The ink according to claim 1, wherein the content of the compound represented by the general formula (I) is in the range of 0.5 to 30% by weight based on the total weight of the ink. 6. An ink jet recording method for recording by ejecting ink as droplets from fine holes by applying thermal energy to the ink according to a recording signal,
An ink jet recording method, wherein the ink contains a pigment, a water-soluble resin, and a compound represented by the following general formula (I) in an aqueous medium. (However, l, m, n represents 0 or a positive integer satisfying the relation of 1 ≦ l + m + n ≦ 25) 7. The ink jet recording method according to claim 6, wherein the recording method is an on-demand type recording method. 8. The ink jet recording method according to claim 6, wherein the amount of the water-soluble resin dissolved in the ink is 2% by weight or less. 9. The ink jet recording method according to claim 6, wherein the aqueous medium of the ink contains water and a water-soluble organic solvent. 10. The ink jet recording method according to claim 9, wherein the water-soluble organic solvent contains a polyhydric alcohol and / or its alkyl ether and an aliphatic monohydric alcohol. 11. The ink jet recording method according to claim 6, wherein the amount of the compound represented by the general formula (I) contained in the ink is in the range of 0.5 to 30% by weight based on the total weight of the ink.