An ink jet recording ink containing water and a coloring material, wherein the ink jet recording ink further contains an ethylenediamine compound represented by Formula (I):wherein R1, R2, R3 and R4 are each selected from the group consisting of a hydrogen atom, an alkyl group and an alkylene oxide group, provided that at least one of R1 and R2 and at least one of R3 and R4 are each an alkylene oxide group, and that alkylene oxide units in one molecule are 2 to 20 in total number.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an ink-jet recording ink (hereinafter often simply “ink”) which is suited for ink-jet recording, does not cause any problem of the curling of recording mediums even when water-based inks are applied in a large quantity to cellulose-containing recording mediums, and affords good response and recording-head sticking resistance also when ejected at a high driving frequency.

2. Related Background Art

Ink-jet recording is a process in which small droplets of ink are made to fly to adhere to a recording medium such as paper to perform recording. According to a thermal ink-jet system in which an electricity-heat converter is used as an ejection energy feed means and heat energy is imparted to an ink to generate air bubbles to eject the droplets, its recording head can easily be made into a high-density multi-orifice head, and images with a high resolution and a high quality can be recorded at a high speed (Japanese Patent Publications Nos. S61-59911, S61-59912 and S61-59914).

Now, inks used in ink-jet recording are commonly those which are chiefly composed of water and, incorporated therein, coloring materials, and also water-soluble high-boiling point solvents such as glycols for the purpose of, e.g., preventing drying and improving recording-head sticking resistance. Where images are recorded on a recording medium containing cellulose as typified by plain paper, trace-coated paper or the like by using such inks, the ejecting of inks in a short time in a region of certain amount or more in area causes a problem that a phenomenon of curling (paper warps or rolls) may come. This problem has not come about in conventional recording performed chiefly for characters or letters, which has been prevalent. However, in recording in which inks are applied in a large quantity as in recording internet home page images or photographic images, such a problem is a great subject to be settled.

The droplets of inks ejected through a single ejection orifice have also been made small in size in order to deal with ink-jet recording images having a very high grade on the level of silver salt photography. At present, ink-jet printers of about 5 pl (picoliters) or less in ink droplet quantity have appeared on the market. Also, with regard to recording speed as well, printers have been demanded to be of much higher speed, and, as what is attendant thereon, it is a matter of great urgency to deal with higher driving frequency or improve recording-head sticking resistance.

In settling such subjects, water-based ink compositions containing various kinds of curling-preventive solvents are proposed (Japanese Patent Applications Laid-open Nos. H6-157955 and H11-12520). Although an effect can be seen to a certain extent in respect of curling resistance, a further improvement is demanded in respect of the simultaneous achievement of response in performing ejection at high driving frequency, recording-head sticking resistance, and curling resistance. Here, the respective subjects are outlined below.

In applying water-based inks in a large quantity to recording mediums containing cellulose, as typified by plain paper, the phenomenon of what is called “curling” may occur and the paper rolls into cylindrical in some cases.

The mechanism by which the curling occurs is considered due to the fact that, in the step of drying paper in the stage of paper making, the water evaporates in the state a tension is applied to a certain direction to form hydrogen bonds between cellulose molecules. Upon adhesion of a water-based ink to the paper that is in such a state, the hydrogen bonds between cellulose molecules break because of the water and the bonded sites are substituted by the water, whereas, upon evaporation of the water, the hydrogen bonds are again formed between cellulose molecules. It is presumed that, when the hydrogen bonds are again formed, no tension is applied there and hence the paper shrinks on the side to which the ink has adhered, so that the curling occurs.

This phenomenon, which can not easily occur in the recording chiefly of characters or letters where the ink is applied in a small quantity, has come into a serious problem in these days where graphic printing is increasingly frequently performed, and it is demanded to improve curling resistance remarkably. This is of great demand especially in a condition where a water-based ink is ejected to a cellulose-containing recording medium of 15 cm2or more in recording area and in an ink-application quantity ranging from 0.03 to 30 mg/cm2.

In an on-demand type ink-jet recording system, an attempt to eject inks continuously at a high driving frequency may make the inks not re-filled in channels in time depending on physical and chemical properties of the inks and inevitably begin to be ejected for the next before the channels are re-filled. As the result, this may cause faulty ejection or bring about a condition where the inks are ejected in a very small quantity. Also, this phenomenon occurs more conspicuously as the droplets of inks ejected are smaller.

As another problem caused by the evaporation of water content of inks that takes place at channel ends, the clogging of channels may be given which occurs due to the sticking of coloring materials at channel ends because of the evaporation of water content; the sticking being caused, e.g., when a printer is left for a certain period of time without being used, or when, in a printer which is of a type its ink tank and printing head are set integral, the printer is left in the state the head itself is detached from the printer, or when, in a printer which is of a form its ink tank and printing head are set separable, the printer is left in the state the ink tank is detached from the printer.

SUMMARY OF THE INVENTION

For the subjects as stated above that involve future technical trends for a background, the present inventors have energetically made studies on an ink-jet recording printer that can maintain at a high level the basic performance required as inks for ink-jet recording, stated specifically, a good response in performing ink ejection at a high driving frequency (stated specifically, a driving frequency which may exceed 10 kHz) and a good recording-head sticking resistance, without making the curling of recording mediums come into question even in respect to recording mediums containing cellulose, and at the same time can deal with highly minute image recording. They have discovered that an ink which is composed to contain a compound having specific properties can achieve such an aim at a high level, and have accomplished the present invention.

Accordingly, an object of the present invention is to provide an ink-jet recording ink that can maintain at a high level a good response in performing ink ejection at a high driving frequency and a good recording-head sticking resistance, without making the curling come into question even in respect to recording mediums containing cellulose, and at the same time can deal with highly minute image recording.

Another object of the present invention is to provide an ink-jet recording method that enables stable formation of high-grade images.

A further object of the present invention is to provide an ink-jet recording apparatus that is applicable to the above ink-jet recording method.

The above objects of the present invention are achieved by the invention described below. That is, the present invention provides an ink-jet recording ink comprising water and a coloring material, wherein the ink-jet recording ink further contains an ethylenediamine compound represented by Formula (I).

wherein R1, R2, R3and R4are each selected from the group consisting of a hydrogen atom, an alkyl group and an alkylene oxide group, provided that at least one of R1and R2and at least one of R3and R4are each an alkylene oxide group, and that alkylene oxide units in one molecule are 2 to 20 in total number.

The present invention is also an ink-jet recording method and an ink-jet recording apparatus which make use of such an ink-jet recording ink.

According to the ink of the present invention, when used in ink-jet recording, it does not make the curling come into question even in respect to the recording mediums containing cellulose, can maintain at a high level the good response in performing ink ejection at a high driving frequency and the good recording-head sticking resistance, and at the same time can deal with highly minute image recording.

As to the response in performing ink ejection at a high driving frequency, it is remarkably effective especially when the thermal ink-jet system is used.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is described below in greater detail by giving preferred embodiments.

The ink according to the present invention comprises water, a coloring material, and an ethylenediamine compound represented by Formula (I).

wherein R1, R2, R3and R4are each selected from the group consisting of a hydrogen atom, an alkyl group and an alkylene oxide group, provided that at least one of R1and R2and at least one of R3and R4are each an alkylene oxide group, and that alkylene oxide units in one molecule are 2 to 20 in total number.

In the ethylenediamine compound represented by Formula (I), R1, R2, R3and R4are each selected from the group consisting of a hydrogen atom, an alkyl group and an alkylene oxide group. The alkyl group in the present invention may include, but is not particularly limited to, a methyl group, an ethyl group and a propyl group, and may be imparted in the range where the compound is well soluble in the ink (water+solvent). The alkylene oxide group is a group having alkylene oxide units. Such alkylene oxide units may preferably be at least one of an ethylene oxide unit and a propylene oxide unit, which are specifically represented by the following structural formula.

The compound represented by Formula (I) as used in the present invention has, for such alkylene oxide units, 2 to 20 units in one molecule. If the number of alkylene oxide units added is more than 20, although the curling may be restrained to a certain extent, the ink may have so high a viscosity that the ink may not be re-filled in channels in time when ejected continuously at a high driving frequency, and may inevitably begin to be ejected for the next before the channels are re-filled, to cause faulty ejection and result in a poor response in performing what is called the ink ejection at a high driving frequency. If on the other hand the number of alkylene oxide units added is less than 2, the effect of restraining the curling is not obtainable.

The ethylenediamine compound in which 2 to 20 alkylene oxide units are added as used in the present invention may variously be synthesized by conventional methods. It may include, e.g., those each having a structure wherein R1, R2, R3and R4are represented by any of (A) to (H) shown in Table 1. Specific compounds may include, but are not limited to, compounds (1) to (14) shown in Table 2.

Incidentally, in the present invention, what is meant by “alkylene oxide units are 2 to 20 in total number in one molecule” is that the alkylene oxide units the R1to R4in Formula (I) have are 2 to 20 in total. For example, in Compound (1) shown in Table 2, one ethylene oxide unit and one propylene oxide unit are added to each of R1to R4, and therefore the alkylene oxide units in one molecule are 8 in total.

The compound of Formula (I) as used in the present invention may be in a content of from 0.5 to 40% by weight, preferably from 1 to 35% by weight, and more preferably from 2 to 30% by weight, based on the total weight of the ink.

The ink according to the present invention contains water as an essential component. The water in the ink may preferably be in a content of 30% by weight or more and also preferably 95% by weight or less, based on the total weight of the ink. Also, an aqueous medium in which the water and a water-soluble solvent are used in combination may often be used.

In the ink according to the present invention, there are no particular limitations on the type and content of the water-soluble solvent used in combination with the water. It may preferably be in a content of, e.g., from 3% by weight or more and also preferably 60% by weight or less, based on the total weight of the ink.

In the ink according to the present invention, in order to achieve more well-balanced ejection stability, it is preferable for the ink to contain a surface-active agent. In particular, the use of a nonionic surface-active agent is preferred. Among the nonionic surface-active agents, polyoxyethylene alkyl ethers and ethylene oxide adducts of acetylene glycol are particularly preferred. The HLB (hydrophilic-lipophilic balance) value of these nonionic surface-active agents is 10 or more. The surface-active agent thus used in combination may be in a content of from 0.01 to 5% by weight, preferably from 0.05 to 4% by weight, and more preferably from 0.1 to 3% by weight, based on the total weight of the ink.

In the ink according to the present invention, in order to make up an ink having the desired values of physical properties, a viscosity modifier, an anti-foaming agent, an antiseptic agent, a mildewproofing agent, an antioxidant and so forth may optionally be added as additives, in addition to the components described above. The additives may preferably be so selected that the ink has a surface tension of 25 mN/m or more, and preferably 28 mN/m or more.

As for the coloring material to be contained in the ink according to the present invention, a dye and a pigment may be used. It may be added to the ink in an amount of, but not limited to the range of, from 0.1 to 15% by weight, preferably from 0.2 to 12% by weight, and more preferably from 0.3 to 10% by weight, based on the total weight of the ink.

As the dye, usable are almost all of water-soluble acid dyes, direct dyes, basic dyes and reactive dyes described in Color Index. Also, even those not described in Color Index may be used as long as they are water-soluble dyes.

Specific examples of the dye used in the present invention are given below. The present invention is by no means limited to these.

Dyes used in black inks may include, e.g., C.I. Food Black 2, and C.I. Direct Black 52, 154, 195.

In the present invention, a pigment may also be used. A pigment used in black inks may preferably be carbon black. Carbon black pigment used in black ink may include, e.g. furnace black, lamp black, acetylene black and channel black. Those having a primary particle diameter of from 15 to 40 nm, a specific surface area of from 50 to 300 m2/g as measured by the BET method, a DBP oil absorption of from 40 to 150 ml/100 g, and a volatile content of from 0.5 to 10% by weight.

As to a dispersing agent used in dispersing the pigment, there are no particular limitations thereon as long as it is water-soluble. Stated specifically, it may include block copolymers, random copolymers or graft copolymers composed of at least two monomers selected from styrene, styrene derivatives, vinylnaphthalene, vinylnaphthalene derivatives, and alcohol esters of α,β-ethylenically unsaturated carboxylic acids, and also acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, fumaric acid derivatives, vinyl acetate, vinylpyrrolidone, acrylamides, and derivatives of these (at least one of these is a hydrophilic monomer); or salts of these copolymers. In particular, dispersing agents especially preferable in order to practicing the present invention are block copolymers. Especially when in a head making use of thermal energy the head is driven at a high driving frequency of, e.g., 10 kHz or more, the use of such a block copolymer in the present invention makes more remarkable the effect of improving ejection performance.

The dispersant in the ink may preferably be in a content within the range of from 0.5 to 10% by weight, preferably from 0.8 to 8% by weight, and more preferably from 1 to 6% by weight, based on the total weight of the ink. If the dispersant is in a content beyond this range, it is difficult to maintain the desired ink viscosity.

The ink-jet recording apparatus according to the present invention is described next, taking the case of an ink-jet printer as a specific example.FIG. 1is a schematic perspective view showing a liquid ejection head as a liquid ejection head of an ejection system in which air bubbles communicate with the atmosphere at the time of ejection, and the main part of an example of an ink-jet printer which is a liquid ejection apparatus making use of this head.

InFIG. 1, the ink-jet printer is constituted to comprise i) a transporting assembly1030which is provided in a casing1008in its lengthwise direction and transports a sheet1028intermittently in the direction shown by an arrow P in the drawing, which sheet is used as a recording medium, ii) a recording part1010which is reciprocated substantially in parallel to and along a guide shaft1014, in the arrow S direction substantially falling at right angles with the direction P in which the sheet1028is transported by the transporting assembly1030, and iii) a movement driving part1006as a driving means which reciprocates the recording part1010.

The transporting assembly1030has a pair of roller units1022aand1022band a pair of roller units1024aand1024bwhich are both disposed opposingly substantially in parallel to each other, and a driving part1020for driving each of these roller units. With such construction, the driving part1020of the transporting assembly1030is brought into the state of operation, whereupon the sheet1028comes to be held between the respective roller units1022aand1022band roller units1024aand1024band be transported in intermittent feed in the direction of an arrow P. The movement driving part1006is constituted to comprise a belt1016put around over a pulley1026aand a pulley1026bwhich are respectively provided on rotating shafts disposed opposingly at a given distance, and a motor1018which drives the belt1016in the regular direction and the reverse direction; the belt1016being disposed substantially in parallel to the roller units1022aand1022band connected to a carriage member1010aof the recording part1010.

At the time the motor1018is brought into the state of operation and the belt1016is rotated in the direction of an arrow R, the carriage member1010aof the recording part1010is moved in the direction of an arrow S by the stated amount of movement. Also, at the time the motor1018is brought into the state of operation and the belt1016is rotated in the direction reverse to the direction of an arrow R shown in the drawing, the carriage member1010aof the recording part1010comes to be moved in the direction reverse to the direction of an arrow S by the stated amount of movement. Further, at one end of the movement driving part1006, a restoration unit1026for performing ejection restoration of the recording part1010is provided opposingly to an ink ejection orifice array of the recording part1010, at a position serving as the home position of the carriage member1010a.

In the recording part1010, ink-jet cartridges (hereinafter often simply “cartridge(s)”)1012Y,1012M,1012C and1012B are each provided detachably to the carriage member1010afor each color, e.g., yellow, magenta, cyan and black.

FIG. 2shows an example of an ink-jet cartridge mountable to the ink-jet recording apparatus described above. A cartridge1012in the example shown in the drawing is of a serial type, and its main part is constituted of an ink-jet recording head100and an ink tank1001which holds inks therein.

In the ink-jet recording head (liquid ejection head)100, a large number of ejection orifices832for ejecting inks therethrough are formed, and are so set up that the inks are led from the ink tank1001to a common liquid chamber (not shown) of the liquid ejection head100via ink feed channels (not shown). The cartridge1012shown inFIG. 2is one in which the ink-jet recording head100and the ink tank1001are integrally formed so that liquids can be replenished into the ink tank1001as occasion calls. It may instead have a structure in which the ink tank1001is replaceably connected to the liquid ejection head100. Incidentally, the ink-jet cartridge having the ink-jet recording head is a recording unit.

EXAMPLES

The present invention is described below in greater detail by giving Examples and Comparative Examples. In the following, “%” is by weight unless particularly noted.

(Preparation of Pigment Dispersion Solution 1)

First, using benzyl methacrylate and methacrylic acid as raw materials, an AB type block polymer having an acid value of 250 and a weight-average molecular weight of 3,000 was produced by a conventional method, which was further neutralized with an aqueous potassium hydroxide solution and then diluted with ion-exchanged water to prepare a homogeneous aqueous 50% by weight polymer solution. Then, 180 g of the aqueous polymer solution obtained, 100 g of C.I. Pigment Blue 15:3 and 220 g of ion-exchanged water were mixed, and then these were stirred for 0.5 hour by a mechanical means. Subsequently, using Microfluidizer (registered trademark; a high shear processor manufactured by MFIC Corporation), the resultant mixture was processed by passing it five times through the interior of an interaction chamber under application of a liquid pressure of about 10,000 psi (about 70 MPa). Further, the pigment dispersion solution obtained as described-above was subjected to centrifugation processing (at 12,000 rpm for 20 minutes) to remove non-dispersible matter which contained coarse particles. Thus, cyan color Pigment Dispersion Solution 1 was obtained. Pigment Dispersion Solution 1 thus obtained was in a pigment concentration of 10% by weight and a dispersant concentration of 10% by weight.

(Preparation of Ink 1)

To prepare Ink 1, the cyan color Pigment Dispersion Solution 1 obtained as described above was used in the amount shown below, and the other components as shown below were added thereto so as to be in the stated concentrations. These components were sufficiently mixed and stirred, followed by pressure filtration with a micro-filter of 2.5 μm in pore size (available from Fuji Photo Film Co., Ltd.) to prepare Ink 1, having a pigment concentration of 2% by weight and a dispersant concentration of 2% by weight.

(Preparation of Pigment Dispersion Solution 2)

100 g of the same aqueous polymer solution as that used in Preparation of Pigment Dispersion Solution 1, 100 g of C.I. Pigment Red 122 and 300 g of ion-exchanged water were mixed, and then these were stirred for 0.5 hour by a mechanical means. Subsequently, using Microfluidizer, the resultant mixture was processed by passing it five times through the interior of an interaction chamber under application of a liquid pressure of about 10,000 psi (about 70 MPa). Further, the pigment dispersion solution obtained as described above was subjected to centrifugation processing (at 12,000 rpm for 20 minutes) to remove non-dispersible matter which contained coarse particles. Thus, magenta color Pigment Dispersion Solution 2 was obtained. Pigment Dispersion Solution 2 thus obtained was in a pigment concentration of 10% by weight and a dispersant concentration of 5% by weight.

(Preparation of Ink 2)

To prepare Ink 2, the above magenta color Pigment Dispersion Solution 2 was used in the amount shown below, and the other components as shown below were added thereto so as to be in the stated concentrations. These components were sufficiently mixed and stirred, followed by pressure filtration with a micro-filter of 2.5 μm in pore size (available from Fuji Photo Film Co., Ltd.) to prepare Ink 2, having a pigment concentration of 4.5% by weight and a dispersant concentration of 2.25% by weight.

(Preparation of Pigment Dispersion Solution 3)

First, using benzyl acrylate and methacrylic acid as raw materials, an AB type block polymer having an acid value of 300 and a weight-average molecular weight of 4,000 was produced by a conventional method, which was further neutralized with an aqueous potassium hydroxide solution and then diluted with ion-exchanged water to prepare a homogeneous aqueous 50% by weight polymer solution. Then, 110 g of the above aqueous polymer solution, 100 g of C.I. Pigment Yellow 128 and 290 g of ion-exchanged water were mixed, and then these were stirred for 0.5 hour by a mechanical means. Subsequently, using Microfluidizer, the resultant mixture was processed by passing it five times through the interior of an interaction chamber under application of a liquid pressure of about 10,000 psi (about 70 MPa). Further, the pigment dispersion solution obtained as described above was subjected to centrifugation processing (at 12,000 rpm for 20 minutes) to remove non-dispersible matter which contained coarse particles. Thus, Pigment Dispersion Solution 3 was obtained. Pigment Dispersion Solution 3 thus obtained was in a pigment concentration of 10% by weight and a dispersant concentration of 6% by weight.

(Preparation of Ink 3)

To prepare Ink 3, the above cyan color Pigment Dispersion Solution 3 was used in the amount shown below, and the other components as shown below were added thereto so as to be in the stated concentrations. These components were sufficiently mixed and stirred, followed by pressure filtration with a micro-filter of 2.5 μm in pore size (available from Fuji Photo Film Co., Ltd.) to prepare Ink 3, having a pigment concentration of 5% by weight and a dispersant concentration of 3% by weight.

(Preparation of Pigment Dispersion Solution 4)

First, using benzyl methacrylate, methacrylic acid and ethoxyethylene glycol methacrylate as raw materials, an ABC type block polymer having an acid value of 350 and a weight-average molecular weight of 5,000 was produced by a conventional method, which was further neutralized with an aqueous potassium hydroxide solution and then diluted with ion-exchanged water to prepare a homogeneous aqueous 50% by weight polymer solution. Then, 60 g of the above aqueous polymer solution, 100 g of carbon black and 340 g of ion-exchanged water were mixed, and then these were stirred for 0.5 hour by a mechanical means. Subsequently, using Microfluidizer, the resultant mixture was processed by passing it five times through the interior of an interaction chamber under application of a liquid pressure of about 10,000 psi (about 70 MPa). Further, the pigment dispersion solution obtained as described above was subjected to centrifugation processing (at 12,000 rpm for 20 minutes) to remove non-dispersible matter which contained coarse particles. Thus, black color Pigment Dispersion Solution 4 was obtained. Pigment Dispersion Solution 4 thus obtained was in a pigment concentration of 10% by weight and a dispersant concentration of 3.5% by weight.

(Preparation of Ink 4)

To prepare Ink 4, the above black color Pigment Dispersion Solution 4 was used in the amount shown below, and the other components as shown below were added thereto so as to be in the stated concentrations. These components were sufficiently mixed and stirred, followed by pressure filtration with a micro-filter of 2.5 μm in pore size (available from Fuji Photo Film Co., Ltd.) to prepare Ink 4, having a pigment concentration of 3% by weight and a dispersant concentration of 1.05% by weight.

(Preparation of Ink 5)

To a mixture solution of ion-exchanged water and an aqueous medium, C.I. Direct Blue 199 and other components as shown below were added with stirring, and these were sufficiently mixed and stirred, followed by pressure filtration with a micro-filter of 2.5 μm in pore size (available from Fuji Photo Film Co., Ltd.) to prepare Ink 5.

(Preparation of Ink 6)

To a mixture solution of ion-exchanged water and an aqueous medium, C.I. Acid Red 52 and other components as shown below were added with stirring, and these were sufficiently mixed and stirred, followed by pressure filtration with a micro-filter of 2.5 μm in pore size (available from Fuji Photo Film Co., Ltd.) to prepare Ink 6.

(Preparation of Ink 7)

To a mixture solution of ion-exchanged water and an aqueous medium, C.I. Direct Yellow 132 and other components as shown below were added with stirring, and these were sufficiently mixed and stirred, followed by pressure filtration with a micro-filter of 2.5 μm in pore size (available from Fuji Photo Film Co., Ltd.) to prepare Ink 7.

(Preparation of Ink 8)

To a mixture solution of ion-exchanged water and an aqueous medium, C.I. Food Black 2 and other components as shown below were added with stirring, and these were sufficiently mixed and stirred, followed by pressure filtration with a micro-filter of 2.5 μm in pore size (available from Fuji Photo Film Co., Ltd.) to prepare Ink 8.

(Preparation of Ink 9)

Ink 9 was obtained in the same manner as in Example 5 except that the ethylene oxide adduct of acetylene glycol in Example 5 was removed to give the following composition.

Comparative Example 1

(Preparation of Ink 10)

Ink 10 was obtained in the same manner as in Example 1 except that Compound (1) in Example 1 was changed for ethylenediamine to give the following composition.

Comparative Example 2

(Preparation of Ink 11)

Ink 11 was obtained in the same manner as in Example 2 except that Compound (4) in Example 2 was changed for Compound (15) to give the following composition.

Comparative Example 3

(Preparation of Ink 12)

Ink 12 was obtained in the same manner as in Example 8 except that Compound (2) in Example 8 was changed for trimethylolpropane to give the following composition.

Comparative Example 4

(Preparation of Ink 13)

Ink 13 was obtained in the same manner as in Example 6 except that Compound (9) in Example 6 was changed for Compound (16) to give the following composition.

Evaluation

The inks obtained in Examples 1 to 9 (Inks 1 to 9) and those in Comparative Examples 1 to 4 (Inks 10 to 13) were evaluated in the following way. An ink-jet recording apparatus (a printer) used in evaluation items (2) and (3) had the construction shown inFIG. 1. Incidentally, its recording head had a recording density of 1,200 dpi, and was 4 pl in ejection volume per dot.

Evaluation Items

Using an ink-jet recording head evaluation instrument manufactured by CANON INC., ink was ejected at a driving frequency of 0.1 kHz. The driving frequency was made gradually higher, and the driving frequency was measured at a point of time where, as the shape of ejection, any primary droplet is no longer present and the ejection became unstable in shape, to make judgment.A: More than 10 kHz.B: 5 kHz or more to 10 kHz or less.C: Less than 5 kHz.

The head mounted to the printer was detached from the main body and left for a week in an environment of 35° C. temperature and 10% relative humidity. Thereafter, it was attached to the printer to check whether or not the printing was recoverable by usual recovery action. Evaluation criteria are as follows. The results of evaluation are shown in Table 3 below.A: Recovered by main-body recovery action taken once.B: Recovered by main-body recovery action taken few times.C: Not recovered by main-body recovery action.

Solid printing was performed on A4-size SW-101 paper manufactured by CANON INC. but leaving blanks at the four sides of the paper by 2 cm each in width. The recorded matter obtained was placed in an environment of 25° C./55% RH, and its condition was visually observed after 1 hour and after a day to make evaluation. Evaluation criteria are as follows. The results of evaluation are shown in Table 3 below.A: The paper is substantially kept flat.B: The paper has risen at edge portions.C: The paper stood cylindrical.

From the results of evaluation (1) to (3) as shown in the above Table 3, it has been confirmed that Inks 1 to 8 according to Examples 1 to 8 are all those having good ink-jet ejection suitability and good curling resistance. Also, in Example 9, the ink contains the compound of Formula (I) but contains no surface-active agent, and hence, although it shows good curling resistance, its response in performing ejection at a high driving frequency is a little inferior to the inks according to Examples 1 to 8 containing the surface-active agent. On the other hand, from the results in Comparative Examples 1 and 2, it has been confirmed that the inks containing compounds in which the number of alkylene oxide units added, of the ethylenediamine is less than 2 have insufficient curling resistance. Also, from the results in Comparative Example 4, it has been confirmed that, although the ink containing the compound in which 20 or more alkylene oxide units are added have good curling resistance, there is a problem on the response in performing ejection at a high driving frequency.

This application claims priority from Japanese Patent Application No. 2004-115598 filed Apr. 9, 2004, which is hereby incorporated by reference herein.