JP2000265098A - Recording liquid for image display and method for forming image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a recording liquid having suitable evaporation properties by compounding water with a colorant and a polyoxyethylene compound. SOLUTION: A polyoxyethylene compound represented by the formula: R- A-(CH2CH2O)X-H (wherein R is a 14-23C linear saturated hydrocarbon group; A is O or OCO; and x is 1-3) is used, examples being an ethylene glycol monoalkyl ether, a diethylene glycol monoalkyl ether, a triethylene glycol monoalkyl ether, an ester formed from ethylene glycol and a long-chain fatty acid, an ester formed from diethylene glycol and a long-chain fatty acid, and an ester formed from triethylene glycol and a long-chain fatty acid. Preferably, the polyoxyethylene compound has a water solubility of 0.001-5 wt.% and is contained in a concentration of 0.001-5 wt.% in the recording liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording liquid for image display suitable for recording by an ink jet system and an image forming method using the same.

[0002]

2. Description of the Related Art As an output device of an information device such as a computer, an ink jet system which is low in running cost, high in definition and easy in color printing has attracted attention. Conventionally, as an ink for inkjet, an ink containing a dye or a pigment as a coloring component and further containing other additives has been mainly used. However, since ink jet is a method of printing by discharging and flying ink from a nozzle, a solid matter is generated from a part of the ink component in the nozzle, and the flying direction of the ink is disturbed and the nozzle is clogged. There was a problem.

In order to solve such a problem, a humectant is generally added to ink. JP-A-6-16984 discloses that the humectant has a vapor pressure of 0.0.
A technique for setting the pressure to 1 mmHg or less is disclosed. Japanese Patent Application Laid-Open No. 8-295834 discloses a technique for combining a specific penetrant with a humectant. However, although the clogging was reduced to some extent by the action of the humectant, these techniques were not able to sufficiently prevent the ejection direction from being disturbed due to the formation of solid matter due to partial evaporation. Cleaning was required, the system became complicated, and printing took a long time.

Further, as means for solving these problems, JP-A-10-95944 discloses an ink technology containing a pigment, a humectant and a long-chain polyethylene oxide-containing dispersant. However, even with this technology,
Precipitation of solids consisting of pigments and dispersants cannot be avoided, and the system must have a dummy jet function, resulting in a system that consumes an excessive amount of ink in addition to printing. JP-A-10-251579 discloses a technique in which a dye and glycerin and an ethylene glycol lower fatty acid ester compound are added to an ink. However, when a dye is used as a colorant, clogging can be avoided. Even if it could be done, it could not cope with the case where a pigment was used as the colorant.

[0005]

As described above, in the conventional ink-jet ink, the formation of a solid phase due to the evaporation of the solvent cannot be prevented, and clogging of the head cannot be avoided. . Therefore, the present invention
By preventing the formation of a solid phase due to the evaporation of the solvent, by preventing deposits and clogging in the nozzles of the ink, an ink capable of obtaining high head reliability, particularly an image suitable for an ink jet printer It is an object of the present invention to provide a recording liquid for display and an image forming method using the same.

[0006]

The inventor of the present invention has conducted intensive studies on the composition ratio of ink that does not evaporate in the head. It has been found that by using a specific polyoxyethylene-based compound having the formula (1), an ink having suitable evaporation characteristics can be obtained, and based on this finding, the present invention has been completed.

That is, the present invention relates to water, a colorant, and the following formula (1) RA- (CH ₂ CH ₂ O) _x -H (1) (where R represents 14 carbon atoms) Wherein A is O or OCO, and x is an integer of 1 to 3). The recording liquid for image display, further comprising a humectant;
The vapor pressure at 0.1 ° C. is not more than 0.1 mmHg,
When its content is from 10% by weight to the recording liquid for image display,
The recording solution for image display, wherein the solubility of the compound of formula (1) in water is 2% by weight;
Wherein the content is 0.001% by weight to 5% by weight at 5 ° C., and the content thereof is 0.001% by weight to 5% by weight based on the recording liquid for image display. An image forming method, wherein recording is performed by an ink jet method using the recording liquid for image formation and the recording liquid for image display.

According to Yoshioka (Koji Yoshioka: Oil Chemistry, Vol. 40, No. 3 (1991), pp. 206-209), it is almost soluble in water in a solution formed of an organic solvent / surfactant / water system. It is described that a non-active surfactant forms a liquid crystal structure at a gas-liquid interface, thereby suppressing evaporation.

Based on the results, the present inventor has determined that a specific compound having low solubility in water and a long linear saturated hydrocarbon bonded to a short polyoxyethylene chain can be converted to water or a solution containing water. More specifically, they have found that the evaporation of an organic solvent / water mixture having a moisturizing ability is suppressed. That is, when the compound of the above formula (1) is added to a recording liquid containing water, a colorant and a humectant, the hydrophilic portion of the compound becomes water or humectant due to the repeating structure of polyoxyethylene 1 to 3. Although the compound is compatible with the agent, the hydrophobic hydrocarbon chain is sufficiently long, and its structure is a linear saturated hydrocarbon. It has been found that by acting the same as a structural surfactant, water or humectants can be prevented from evaporating. Further, by defining the saturated vapor pressure and the amount of addition, which are related to the evaporation characteristics of the added humectant, the evaporation of the ink can be prevented. It has been found that it is possible to supply a highly reliable printer without clogging, and it is possible to obtain a high-quality image without color loss by using this printer.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The recording liquid for image display of the present invention contains water, a colorant, and a compound represented by the following formula (1) as essential components. The compound which can be used in the recording liquid of the present invention is represented by the following formula (1) RA- (CH ₂ CH ₂ O) _x -H (1) (wherein, R represents 14 to 23 carbon atoms) Wherein A is O or OCO, and x is an integer of 1-3.

In the above formula, the hydrocarbon chain of R is a hydrophobic site, and exists in the gas phase at the gas-liquid interface of the ink. R is required to be linear. When R is branched,
Compounds lined up at the gas-liquid interface cannot exist densely, which is not preferable. Further, R is required to be a saturated hydrocarbon. When R is an unsaturated hydrocarbon containing a double bond, the hydrocarbon chain is bent at the double bond, so that the compounds cannot be closely arranged, and further, a chemical change such as oxidation occurs. It is not preferable because it is easy and unstable.

R is required to be 14 to 23.
When R is less than 14, the length of the hydrocarbon is not sufficient, and thus, even if a compound is added, the evaporation behavior is not suppressed, which is not preferable. On the other hand, if R exceeds 23, the hydrophobicity becomes too large, and the necessary minimum solubility in the ink cannot be obtained. When A is O,
R preferably has 15 to 23 carbon atoms, and A is OC
In the case of O, R preferably has a fractional number of 14 to 22.

The compound represented by the above (1) includes monoalkyl ethers of ethylene glycol, monoalkyl ethers of diethylene glycol, monoalkyl ethers of triethylene glycol, ester compounds comprising ethylene glycol and long-chain fatty acids, and diethylene glycol An ester compound composed of a chain fatty acid and an ester compound composed of triethylene glycol and a long-chain fatty acid are exemplified. Specific examples of these compounds include ethylene glycol cetyl ether, diethylene glycol cetyl ether, triethylene glycol cetyl ether, ethylene glycol stearyl ether, diethylene glycol stearyl ether, triethylene glycol stearyl ether, ethylene glycol araquinyl ether, diethylene glycol araquinyl ether, and triethylene glycol araquinyl ether. Ethylene glycol araquinyl ether, ethylene glycol behenyl ether, diethylene glycol behenyl ether, triethylene glycol behenyl ether, ethylene glycol monopalmitate, diethylene glycol monopalmitate, triethylene glycol monopalmitate, ethylene glycol monostearate, diethyl ether monostearate Glycol, monostearate triethylene glycol, Monoarakijin ethylene glycol, Monoarakijin diethylene glycol, Monoarakijin acid triethylene glycol, monobehenate ethylene glycol, monobehenate acid diethylene glycol, triethylene glycol, and the like monobehenate acid.

The solubility of the compound of formula (1) in water is
It is preferably in the range of 0.001% to 5% by weight. If the solubility exceeds 5% by weight, the compound of the above formula (1) forms micelles and dissolves in the ink rather than lined up at the gas-liquid interface, which is undesirable because the effect of controlling evaporation is reduced. On the other hand, if the solubility of the compound of the above formula (1) is less than 0.001% by weight, the amount of the compound which can be added to the ink becomes insufficient, and the effect of controlling evaporation cannot be provided, which is not preferable.

The content of the compound of the above formula (1) is preferably 0.001% by weight to 5% by weight based on the recording liquid for image display.
% By weight, more preferably 0.005% to 3% by weight
Hereinafter, the content is particularly preferably 0.01% by weight to 1% by weight. If the content is less than 0.001% by weight, the amount of the compound of the above formula (1) arranged at the gas-liquid interface of the ink becomes insufficient, and the effect of controlling evaporation cannot be provided. On the other hand, if the content exceeds 5% by weight, the compound of the above formula (1) becomes insoluble and precipitates as a solid in the ink, which may cause clogging.

In the ink jet recording ink of the present invention, various dyes, pigments, colored polymers / waxes and the like can be used as the colorant as an essential component.
Among them, it is preferable to use a water-soluble dye. As the water-soluble dye, any of an acid dye, a direct dye, a basic dye, a reactive dye and the like can be used, but an acid dye and a direct dye are more preferable.

Examples of the acid dye and the direct dye include, for example,
CI Direct Black-2, -4, -9, -11,
-17, -19, -22, -32, -80, -151,
-154, -168, -171 and -194, CI Direct Blue-1, -2, -6, -8, -22, -3
4, -70, -71, -76, -78, -86, -11
2, -142, -165, -199, -200, -20
1, -202, -203, -207, -218, -23
6 and -287, CI Direct Red-1, -2,
-4, -8, -9, -11, -13, -15, -20,
-28, -31, -33, -37, -39, -51,-
59, -62, -63, -73, -75, -80, -8
1, -83, -87, -90, -94, -95, -9
9, -101, -110 and -189, CI Direct Yellow-1, -2, -4, -8, -11, -12,
-26, -27, -28, -33, -34, -41,-
44, -48, -58, -86, -87, -88, -1
35, -142 and -144, CI Food Black-
1 and -2, CI Acid Black-1, -2,-
7, -16, -24, -26, -28, -31, -4
8, -52, -63, -107, -112, -118,
-119, -121, -156, -172, -194 and -208, CI Acid Blue-1, -7, -9,
-15, -22, -23, -27, -29, -40,-
43, -55, -59, -62, -78, -80, -8
1, -83, -90, -102, -104, -111,
-185, -249 and -254, CI Acid Red-1, -4, -8, -13, -14, -15, -1
8, -21, -26, -35, -37, -110, -1
44. -180, -249 and -257, C.I. I. Acid Yellow-1, -3, -4, -7, -11, -1
2, -13, -14, -18, -19, -23, -2
5, -34, -38, -41, -42, -44, -5
3, -55, -61, -71, -76, -78, -79
And -122.

Although these dyes can be used alone,
Mix two or more, cyan, magenta, yellow,
In addition to the four primary colors of black, custom colors such as red, blue, and green may be used. It is also possible to use a pigment, for example, carbon black, brilliant carmine BS, lake carmine FB, brilliant fast scarlet, disazo yellow, permanent red R, fast yellow 10G, phthalocyanine blue,
Blue lake, yellow lake, rhodamine lake and the like can be used.

The content of these coloring agents depends on the type of dye,
It is determined depending on the type of the solvent and the characteristics required for the recording liquid. In order to exhibit the function as a colorant, the recording liquid for image display is generally 0.1. ~ 2
0% by weight, more preferably 1 to 10% by weight. If the content of the coloring agent is less than 0.1% by weight, sufficient color developability cannot be obtained, which is not preferable. If it exceeds 20% by weight, the ink thickens and causes clogging, which is not preferable.

The water which is an essential component of the recording liquid for image display of the present invention includes distilled water, ion-exchanged water, pure water and the like.
Can be used.

The recording liquid for image display of the present invention preferably contains a humectant having a sufficiently low evaporation rate as compared with water. Representative examples of the humectant include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol having high wettability (hygroscopicity),
Alkylene glycols such as dipropylene glycol, trimethylene glycol, butylene glycol, pentamethylene glycol, hexylene glycol, octylene glycol, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tripropylene glycol monomethyl ether And polyalkylene glycols such as polyethylene glycol and polypropylene glycol; glycerin; and amines such as triethanolamine and diethylethanolamine.

The humectant for making the present invention work effectively is added in order to obtain a sufficient effect of preventing clogging, and has a vapor pressure of 0.1 mmHg at a temperature of 25 ° C.
The following are preferred, and those having 0.01 mmHg or less are more preferred. Specifically, diethylene glycol, triethylene glycol, dipropylene glycol, pentamethylene glycol, octylene glycol, polyethylene glycol, polypropylene glycol, glycerin, triethanolamine, and the like have a vapor pressure of 0.01 mmHg or less at room temperature. Particularly suitable for use in the invention.

One type of these humectants may be used alone, but when they are completely mixed to form one phase, two or more types may be used in combination. The content of the humectant must be an amount that can control the evaporation of the recording liquid,
The amount is preferably about 10 to 90% by weight, more preferably about 30 to 80% by weight, and still more preferably about 50 to 75% by weight, based on the recording liquid for image display. 1 moisturizer content
If it is less than 0% by weight, a sufficient moisturizing effect cannot be exhibited,
Not preferred. On the other hand, when the content exceeds 90% by weight, the solubility of the dye is reduced or the viscosity is increased, so that the ejection becomes difficult, which is not preferable.

The recording liquid of the present invention may further contain other additives. For the purpose of further stabilizing the dissolution or dispersion state of the dye or pigment, a low molecular surfactant can be added. As the low molecular surfactant, any of nonionic, anionic, cationic and amphoteric surfactants may be used.For example, nonionic surfactants include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl Phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid alkylolamide and the like can be used.

As the anionic surfactant, alkyl benzene sulfonate, alkyl phenyl sulfonate,
Alkyl naphthalene sulfonate, higher fatty acid salt, higher fatty acid ester sulfate, higher fatty acid ester sulfonate, higher alcohol ether sulfate and sulfonate, higher alkyl sulfosuccinate, etc .; cationic surfactant As the first to third
Grade amine salts, quaternary ammonium salts and the like; and as the amphoteric surfactant, betaine, sulfobetaine, sulfate betaine and the like can be used. The content of these surfactants is preferably not more than twice, more preferably equal to or less than the content of the compound of the formula (1) so as not to impair the effect of the surfactant for controlling evaporation.

In addition, the recording liquid for image display of the present invention includes:
As a solubilizing agent, urea, acetamide and the like may be contained, and as a pH adjusting agent, acids such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid and citric acid and bases such as sodium hydroxide, potassium hydroxide and ammonia; And various buffering agents such as phosphates, oxalates and amine salts. In addition, polyethyleneimine, polyamines,
Cyclodextrin, macrocyclic amines, crown ethers, and the like may be contained as inclusion compounds such as polyvinylpyrrolidone, polyethylene glycol, and cellulose derivatives, and may contain a fungicide if necessary.

The production of the recording liquid for image display of the present invention can be carried out by the following procedure, but is not limited thereto. That is, water, the colorant, and the formula (1)
Is dispersed in a ball mill, and it is confirmed by microscopic observation that the colorant particles are in a monodispersed or completely dissolved state.After that, an additive such as a dispersant is added, and Allow to dissolve. At this time, if necessary, the mixture may be heated to the dissolution temperature of the additive. Then
This dispersion is filtered through, for example, a membrane filter having a pore size of 10 μm to remove dust and coarse particles, thereby obtaining a recording liquid for image display.

The printing of the recording liquid of the present invention on recording paper can be carried out by using an ink jet printer which performs printing by discharging ink from nozzles, but is not limited thereto. As an inkjet discharging method, any of a thermal inkjet type (bubble jet type) and a piezo type may be used.

As the paper on which the recording liquid for image display of the present invention is printed, any of plain paper, PPC paper, and various kinds of special papers can be used. From the point of view, it is particularly preferable to use paper dedicated to inkjet.

(Operation) Since the recording liquid of the present invention does not evaporate in the nozzle, there is no formation of deposits associated therewith, and the recording liquid is highly reliable. Further, since no clogging of the head occurs, a dummy jet or a nozzle cleaning system is not required, the apparatus is not increased in size, and the system is simple, so that the speed can be increased. An image printed by an inkjet printer using the recording liquid of the present invention is a highly reliable image without missing dots.

[0031]

The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited by these examples. Parts used in the examples are parts by weight unless otherwise specified.

(Example 1) Distilled water 48 parts Diethylene glycol 50 parts Cyan dye (CI Acid Blue-9: manufactured by Mitsubishi Chemical Corporation) 2 parts Diethylene glycol monostearyl ether 0.1 part The above composition was placed in an Erlenmeyer flask. In a state where the mixture was heated to 90 ° C., the mixture was stirred for 30 minutes using a magnetic stirrer with a heating device, and was dissolved in advance. This was subjected to pressure filtration under a heating condition of 90 ° C. using a membrane filter having a pore diameter of 10 μm to obtain a recording liquid 1.

(Example 2) Distilled water 70 parts Glycerin 30 parts Cyan dye (CI Acid Blue-9: manufactured by Mitsubishi Chemical Corporation) 2 parts Diethylene glycol monostearate 0.05 part The same composition as in Example 1 was used. The mixture was mixed and filtered to obtain a recording liquid 2.

(Comparative Example 1) Distilled water 88 parts Diethylene glycol monobutyl ether 5 parts Glycerin 5 parts Cyan dye (CI Acid Blue-9: manufactured by Mitsubishi Chemical Corporation) 2 parts The above composition was heated to 40 ° C in a water bath. With a magnetic stirrer and then with a pore size of 0.25
The solution was filtered under pressure with a membrane filter of μm to obtain recording solution 3.

(Comparative Example 2) Water 48 parts Diethylene glycol 50 parts Cyan dye (CI Acid Blue-9: manufactured by Mitsubishi Chemical Corporation) 2 parts The above composition was mixed and filtered in the same manner as in Example 1, and recorded. Liquid 4.

(Example 3) Distilled water 28 parts Triethylene glycol 70 parts Cyan dye (CI Acid Blue-9: manufactured by Mitsubishi Chemical Corporation) 2 parts Triethylene glycol monobehenyl ether 0.1 part The above composition was prepared as an example. The mixture was mixed and filtered in the same manner as in Example 1 to obtain a recording liquid 5.

(Example 4) Distilled water 48 parts Diethylene glycol 50 parts Cyan dye (CI Acid Blue-9: manufactured by Mitsubishi Chemical Corporation) 2 parts Diethylene glycol monopalmitate 1 part The above composition was mixed and mixed in the same manner as in Example 1. After filtration, recording liquid 6 was obtained.

Comparative Example 3 Example 1 was repeated using diethylene glycol monolauryl ether in place of diethylene glycol monostearyl ether in Example 1.
The mixture was mixed and filtered in the same manner as described above to obtain a recording liquid 7.

Comparative Example 4 A recording liquid 8 was obtained by mixing and filtering in the same manner as in Example 1 except that polyoxyethylene (55) monostearate was used instead of diethylene glycol monostearyl ether in Example 1.

(Test Examples) Examples 1-4 and Comparative Examples 1-4
The following A, B, and C were evaluated with respect to the recording liquid prepared in the above. Measurement of evaporation rate of A recording liquid 10 g of ink was measured on a petri dish having a diameter of 5 cm and a depth of 3 cm, and the weight change after 24 hours of exposure and opening in an environment of a temperature of 25 ° C. and a humidity of 65% was confirmed. The residual weight ratio was calculated according to the equation of 2). The results are shown in FIG. In addition, when the remaining weight ratio was 90%, it was determined that there was no change in weight, and when the remaining weight ratio was 95%, the value was more preferable.

[0041]

## EQU1 ## [(sample weight (g) after 24 hours) / (initial sample weight (g))] × 100 = remaining weight ratio (%)

B. Clogging model test Ink was sealed in a capillary tube 1 having a capacity of 0.5 μl and a length of 30 mm shown in FIG. 1 using a rubber pipettor 2 and both ends were opened. It was left for one week in the environment, and changes immediately after and one week after the encapsulation were confirmed by microscopic observation.

C actual machine test A commercially available thermal ink-jet printer was modified with a printing device filled with a recording liquid, left in this state at 40 ° C. without a cap for one month, and then subjected to ink-jet paper (JP-C100A: (Sanwa Supply Co., Ltd.). The sample printed in this manner was observed using a loupe with a magnification of 10 to see if dots were completely hit. Table 1 shows the evaluation results of AC.

[0044]

[Table 1]

The recording liquids for image display of Examples 1 to 4 hardly evaporated and hardly changed in weight even when exposed to exposure, as compared with the recording liquids for image display of Comparative Examples 1 to 4. .
In addition, since the recording liquids for image display of Examples 1 to 4 did not change due to evaporation, there was no generation of solids such as a decrease in ink capacity and precipitation of additives accompanying the reduction. In particular, Comparative Example 1,
In No. 2, the compound replacing the formula (1) was not added at all, and the amount of the humectant added was insufficient, so that a solid was precipitated and clogging was considered to be caused by this. In addition, in Comparative Examples 3 and 4, in which the number of carbon atoms of R in the formula (1) is out of the range of the present invention, the effect of preventing evaporation is not obtained. In particular, the recording liquids for image display of Examples 1, 3, and 4 had a humectant addition amount of 50 compared to the recording liquid of Example 2.
Since the content was not less than weight%, the amount of evaporation was further reduced. Furthermore, when these recording liquids were evaluated on an actual machine,
The recording liquids for image display of Examples 1 to 4 provided a highly reliable image free from dot missing and disturbance without maintenance.

[0046]

According to the present invention, there is provided an image display recording liquid capable of preventing formation of a solid phase without evaporating the solvent component in the ink, thereby preventing head clogging. You. By using the recording liquid for image display of the present invention, an image can be formed by a small and simple ink jet printer that does not require a special system such as a dummy jet or a nozzle cleaning system.
Further, when the recording liquid for image display of the present invention is used, a maintenance mechanism is not required in the printer, so that printing can be performed at high speed, and a highly reliable image without dot missing can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an ink filling device used in a clogging model test.

FIG. 2 is a graph showing a change in weight with time according to an evaporation test.

[Description of Signs] 1 Capillary tube 2 Rubber pipettor 3 Joint

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C056 FC01 2H086 BA55 BA59 4J039 BC07 BC13 BC20 BC39 BC60 BE01 BE03 BE04 BE05 BE22 CA03 CA06 EA11 EA15 EA16 EA17 EA19 EA41 EA42 EA44 GA24

Claims (2)

[Claims] 1. Water, a colorant, and the following formula (1) RA- (CH ₂ CH ₂ O) _x -H (1) (wherein R is a straight-chain having 14 to 23 carbon atoms) Wherein the compound is a chain saturated hydrocarbon, A is O or OCO, and x is an integer of 1 to 3). 2. An image forming method using the recording liquid for image display according to claim 1 and recording by an ink jet method.