JPH05148436A - Ink jet recording liquid, its production and method for ink jet recording using the same - Google Patents

Abstract

PURPOSE:To obtain the subject recording liquid, always and stably dischargeable and excellent in preservation stability for a long period without solidifying the ink at the head tip by dispersing a specific pigment and a water-soluble resin in the coexistence of an aqueous medium and then adding the aqueous medium to the resultant dispersion. CONSTITUTION:The objective recording liquid is obtained by dispersing (A) a quinacridone-based compound pigment expressed by the formula (R is H, CH3 or Cl) and (B) a water-soluble resin (preferably a styrene-acrylic acid copolymer, etc.) at (15:1) to (30:1) weight ratio in the coexistence of (C) an aqueous medium and then adding the component (C) to the resultant pigment dispersion. The obtained recording liquid contains the components (A) to (C). A mixed solvent of ion exchange water with a water-soluble organic solvent is preferred as the component (C). Triols such as glycerol are preferred as the water-soluble organic solvent. Ethanol or isopropyl alcohol in an amount of >=3% is preferably used in combination from the viewpoint of discharge stability of 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 suitable for an ink jet printer, and to a recording method for recording on a so-called plain paper by causing the recording liquid to fly from an orifice of a recording head by the action of thermal energy.

[0002]

2. Description of the Related Art The ink jet recording system has an advantage that noise is not generated during recording and a high resolution recording image is obtained at a high speed by using a highly integrated head. In such an ink jet recording system, as an ink, a solution in which various water-soluble dyes are dissolved 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, if the recorded image is exposed to rain, sweat, or water from food or drink,
The recorded image may bleed or disappear. In particular, with a magenta dye, it is difficult to achieve both color tone, light resistance, and water resistance, and various attempts have been made, but sufficient performance has not yet been obtained.

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 in order to solve the problems of light resistance and water resistance. As an example of studying dispersion stability, prevention of ink solidification at a pen tip, and prevention of abrasion of balls of a ballpoint pen for practical use of water-based pigment ink, JP-A-58-803 is cited.
68, JP 61-200182, JP 61-247774, and JP 61-272278.
JP-A-62-568, JP-A-62-10
1671, 101672, Japanese Patent Laid-Open No. 1-24986.
No. 9,1-301,760, etc. are mentioned. Recently, ballpoint pens and markers using water-based pigment inks and markers are on the market as products, and as water-based pigment inks using red pigments, JP-A-54-10023 and JP-A-Sho-6.
1-155280, JP 61-200182, JP 61-247774, JP 62-568, JP 1-
No. 117975 is cited.

On the other hand, the ink jet recording liquid is required to have a performance different from that of the aqueous pigment ink for stationery, and the amount of impurities is specified in JP-A-1-204979 and JP-A-1-204980. Therefore, there is a technology for improving reliability, and when applying a dispersion system called pigment ink to inkjet recording, prevention of ink solidification at the head of the head by leaving it for a long time is an important technical issue, and reliability is high. The composition of the ink is an important point in designing the pigment ink. JP-A 1-28
Japanese Patent No. 2273 discusses prevention of solidification at the head tip. However, even with these known techniques, an ink excellent in ejection stability using a pigment having a stable color has not been obtained.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention When a conventional aqueous pigment ink for stationery is used as it is in an ink jet recording system by causing a recording liquid to fly from the orifice of a recording head by the action of thermal energy, there is a significant obstacle to ejection stability. Wake up.

Further, among the conventional aqueous pigment inks,
Although the ejection property is excellent in a relatively short time, when the driving condition of the recording head is changed or the continuous ejection is performed for a long time, the ejection becomes unstable and finally the ejection is stopped.

[0008] Therefore, an object of the present invention is to provide a water-based pigment ink having a magenta color with good long-term stability.

Further, the object of the present invention is to solve the above-mentioned problems of the technology, to enable stable ejection at all times even when the driving conditions are varied or to be used for a long time, and it is excellent in long-term storage stability. An object of the present invention is to provide a magenta color recording liquid for ink jet in which solidification of ink at the head end is eliminated.

It is a further object of the present invention to provide an ink jet recording method capable of always performing stable high speed recording and printing on an uncoated paper to give a recorded image excellent in fastness such as water resistance and light resistance. Especially.

[0011]

The above-mentioned objects can be achieved by the present invention described below.

That is, in the present invention, a pigment is used in combination with a water-soluble resin in an ink containing an aqueous medium containing a polyhydric alcohol and / or its alkyl ether and an aliphatic monohydric alcohol. It is a quinacridone compound represented by the formula, and the weight ratio of the pigment to the water-soluble resin is 15: 1 to 3
A recording liquid in the range of 0: 1 and a method for producing the recording liquid, and an inkjet recording method for recording by applying thermal energy to the recording liquid and ejecting it as droplets from fine holes.

[0013]

[Chemical 3] However, the present invention will be described in detail below with R: H, CH ₃ , and Cl.

The recording liquid of the present invention has various properties particularly suitable for an ink jet printer using heat energy.

The present inventors prepared red pigments having various chemical structures with the composition conventionally proposed for stationery and the like for application to an ink jet printer using an aqueous pigment ink having a magenta color, and variously prepared. It was found that the pigment of the above-mentioned general formula exhibited extremely good color tone and fastness when the fastness and color tone were evaluated by coating on the recording paper of No. 2. Therefore, when these inks were used in an ink jet recording apparatus utilizing heat energy, there was a problem that a remarkable print ejection still occurred and a good printed matter could not be obtained. Therefore, the present inventors further investigated the cause and found some factors. One is that when a pulse is applied to such conventional stationery ink, a deposit is formed on the thin-film heating resistor due to the effect of the heat, and the ink foaming is incomplete, which causes ejection disorder or ejection failure. That is. Further, even if no deposit is generated on the thin film resistor, foaming may be incomplete and the ejection of droplets may not respond to the applied pulse, resulting in ejection failure. That is, in order to stably eject the ink from the tip of the nozzle, it is necessary that the ink be foamed to a desired volume on the thin film resistor and that bubbling and defoaming be repeated at a desired time. However, since the conventional stationery inks do not consider their performances at all, the above various inconveniences occur when the ink is directly filled in the ink jet recording apparatus to perform recording.

Accordingly, the inventors of the present invention have conducted extensive studies as to the formulation of an ink that is thermally stable with an aqueous pigment ink and that is capable of optimal foaming, and as a result, found that a pigment represented by the above general formula contained in a recording liquid was used. The weight ratio of the water-soluble resin is set in the range of 15: 1 to 30: 1, and the polyhydric alcohol and the aliphatic monohydric alcohol are used in combination as the water-soluble organic solvent. By containing 10% or more with respect to the total weight, it is possible to always stably discharge ink without generating deposits on the thin-film heating resistor, and thus the present invention has been completed.

The ink jet recording liquid of the present invention combines a pigment with a water-soluble resin to maintain long-term stability. If the ratio of the water-soluble resin to the pigment is less than 30: 1, it is stable. Ink is not obtained,
On the other hand, if it is larger than 15: 1, the above-mentioned inconvenience occurs. It is considered that the water-soluble resin may contribute to stability by being adsorbed by the pigment.

As the pigment used in the present invention, any quinacridone pigment represented by the above-mentioned general formula, which is a magenta color, can be used, but CI PIGMENT RED 12
2,209, CI PIGMENT VIOLET 19 etc., specifically, HOSTAPERM REDEG TRANS., HOSTAPERM RED VIOLET
ER-02, HOSTAPERM RED E5B02, HOSTAPERM PINK E (Hoec
hst), Fastogen Super Magenta RT, Fastogen Super
Red 7083Y (manufactured by Dainippon Ink), Fuji Fast Red 9900RM
(Manufactured by Fuji dye) and the like. The amount of the pigment used in the present invention is preferably 3 to 30% by weight in the recording liquid.

Since there is a concern that the ink will solidify at the tip of the head, means such as increasing the airtightness of the cap, periodically cleaning the face surface of the head with a wiper, or providing a cleaning means with alkali in the apparatus are provided. It is known to take. These measures are not always preferable solutions in terms of cost and safety. For this reason, the present inventors have examined means for preventing solidification of the ink at the head tip by improving the constituent elements of the ink, and as described above, by using the pigment in combination with a water-soluble resin, It was found that the solidification of the ink at the tip of the head is remarkably improved by containing at least 10% (part by weight) of polyhydric alcohol.

The water-soluble resin used as a pigment dispersant in the recording liquid of the present invention is soluble in an aqueous solution in which an amine or a base is dissolved, and usually has a weight average molecular weight of 3,000 to 30,000. Furthermore, preferably 5000 to 15
It is in the range of 000. Styrene-acrylic acid copolymers, styrene-acrylic acid-acrylic acid alkyl ester copolymers, styrene-maleic acid copolymers, styrene-maleic acid are those that easily satisfy this condition and can be preferably used in the present invention. -Acrylic acid alkyl ester copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-maleic acid half ester copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl Naphthalene-maleic acid copolymer, styrene-maleic anhydride-
Examples thereof include maleic acid half ester copolymers and salts thereof. The water-soluble resin is preferably contained in the range of 0.05 to 1% by weight based on the total amount of the recording liquid.

Examples of pH adjusters that can be used in the recording liquid of the present invention include various organic amines such as monoethanolamine, diethanolamine and triethanolamine, sodium hydroxide, lithium hydroxide, potassium hydroxide and the like. Inorganic alkaline agents such as hydroxides of alkali metals, organic acids, and mineral acids can be used.

These pigments and water-soluble resins are dispersed or dissolved in an aqueous medium.

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

Other optional solvent components that can be used in combination with the recording liquid of the present invention include water-soluble organic solvents such as methyl alcohol, n-propyl alcohol, and n.
-Butyl alcohol, sec-butyl alcohol, te
alkyl alcohols having 1 to 4 carbon atoms such as rt-butyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketones or ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyethylene glycol, Polyalkylene glycols such as polypropylene glycol; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, thiodiglycol, hexylene glycol, diethylene glycol, and other alkylene groups containing 2 to 6 carbon atoms; ethylene; Glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monomethyl (also Lower alkyl ethers of polyhydric alcohols ethyl) ether; N- methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone. 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. Of the polyhydric alcohols, triol is a highly hygroscopic solvent,
Particularly preferred. Examples of the triol used in the present invention include glycerin, 1,2,6-hexanetriol, petriol (trade name), and trimethylolpropane, and any derivative can be used as long as it has good hygroscopicity.

It has been found that it is effective to add ethanol or isopropyl alcohol in an amount of 3% or more in order to obtain the ejection stability of the recording liquid. It is considered that this is because the addition of these makes it possible to more stably foam the recording liquid on the thin film resistor. However, it has been found that an appropriate concentration of these is 3 to 10%, because the excessive addition of these causes a drawback that the print quality of the printed matter is impaired. Furthermore, as these effects, it is possible to suppress the generation of bubbles during dispersion and to perform efficient dispersion by adding these to the dispersion liquid.

In the recording liquid of the present invention, the total content of the above water-soluble organic solvent is generally in the range of 3 to 50% by weight, preferably 3 to 40% by weight based on the total weight of the recording liquid. , The water used is 10 to 90% by weight of the total weight of the recording liquid,
It is preferably in the range of 30 to 80% by weight.

In addition to the above components, the recording liquid of the present invention may be added with a surfactant, an antifoaming agent, an antiseptic agent, etc. in order to have desired physical properties, if necessary. The water-soluble dye etc. can also be added as long as the object of the present invention is not impaired.

Surfactants can also be used in combination, and these include fatty acid salts, higher alcohol sulfate ester salts, liquid fatty oil sulfate ester salts, anionic surfactants such as alkylallyl sulfonates, and polyoxyethylene alkyl. There are nonionic surfactants such as ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan alkyl esters, and one or more of these can be appropriately selected and used. The amount used varies depending on the dispersant, but is preferably 0.01 to 5% by weight with respect to the total amount of the ink.

At this time, the surface tension of the recording liquid is 30 dyne / cm.
It is preferable to determine the addition amount of the activator as described above. The reason why the surface tension of the recording liquid is smaller than this value 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. Because.

Further, it is desirable that the pigment and the water-soluble resin are previously mixed in a pigment dispersion liquid of 10% or more, preferably 30% or less on a weight basis, and then further formulated in a recording liquid.
The reason is that it is convenient to allow the pigment and the water-soluble resin to exist in the dispersion liquid at a certain concentration or more to efficiently disperse the pigment and obtain an optimal dispersion state.

In the method of preparing the recording liquid of the present invention, first, a water-soluble resin is added to an aqueous solution containing an amine or a base, a pigment is further added, the mixture is stirred and dispersed, and a centrifugal treatment is carried out if necessary. To obtain the desired dispersion.
Next, the above-mentioned components are added to this dispersion, and the mixture is stirred to form a recording liquid.

The amount of amine or base that dissolves the water-soluble resin is preferably added in an amount equal to or more than the amount of amine or base calculated from the acid value of the resin. The amount of this amine or base is calculated by the following formula.

Amount of amine or base (g) = (acid value of resin * molecular weight of amine or base * resin amount (g)) /
56000 (Note: KOH has a molecular weight of 56.) It is also preferable to perform premixing for 30 minutes or more before the dispersion treatment of the aqueous solution containing the pigment. This premixing operation improves the wettability of the pigment surface and promotes adsorption on the pigment surface.

The amines added to the dispersion are preferably organic amines such as monoethanolamine, diethanolamine, triethanolamine and aminomethylpropanol, or ammonia. As the base added to the dispersion liquid, an inorganic alkaline agent such as a hydrate of an alkali metal salt such as sodium hydroxide, lithium hydroxide or potassium hydroxide is preferable.

On the other hand, the disperser used in the practice of the present invention may be any commonly used disperser, and examples thereof include a bor mill, a roll mill and a sand mill. Among them, a high speed type sand mill is preferable, and examples thereof include a super mill, a sand grinder, a bead mill, an agitator mill, a grain mill, a dyno mill, a pearl mill, and a cobol mill (all are trade names).

In the present invention, commercially available pigments are usually sufficient, but as a method for obtaining a pigment having a desired particle size distribution, the size of the pulverizing media in the disperser can be reduced, and the filling rate of the pulverizing media can be reduced. Is used, the processing time is lengthened, the discharge speed is slowed, and after crushing, classification is performed with a filter, a centrifuge or the like. Alternatively, a combination of these methods may be used.

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

As a recording apparatus suitable for recording using the recording liquid of the present invention, thermal energy corresponding to a recording signal is applied to ink in the chamber of the recording head (hereinafter referred to as recording liquid), and An example is a device that generates droplets. The apparatus will be described briefly, but this is an example and the practice of the invention is not limited by the following.

FIG. 1 shows an example of the head structure, which is the main part of the structure.
(A), FIG.1 (b), and FIG. The head 13 is made of glass, ceramics, a plastic plate or the like having a groove 14 through which ink passes, and a heating head 15 used for thermal recording (thin film is shown in the figure, but not limited to this). It is obtained by bonding and. The heating head 15 includes a protective film 16 made of silicon oxide, aluminum electrodes 17-1 and 17-2, a heating resistor layer 18 made of nichrome, a heat storage layer 19, and a substrate having good heat dissipation such as alumina. Twenty.

The ink 21 is a discharge orifice (fine hole) 2
The pressure meniscus 23 is formed 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 rapidly generates heat, and bubbles are generated in the ink 21 in contact therewith, and the pressure thereof is generated. Then, the meniscus 23 is projected, the ink 21 is ejected, and becomes a recording droplet 24 from the orifice 22 and flies toward the recording medium 25. FIG. 2 shows an external view of a multi-head in which many heads shown in FIG. The multi-head includes a glass plate 27 having a multi-groove 26,
It is made by bonding a heating head 28 similar to that described in FIG.

Incidentally, FIG. 1A is a sectional view of the head 13 along the ink flow path, and FIG. 1B is a sectional view of FIG.
-It is a cross section at line B.

FIG. 3 shows an example of an ink jet recording apparatus incorporating such a head. 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. The blade 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 movement path of the recording head. Reference numeral 62 denotes a cap, which is arranged at a home position adjacent to the blade 61, and has a configuration for moving in a direction perpendicular to the moving direction of the recording head and abutting the ejection surface for capping. Further, 63 is an ink absorber provided adjacent to the blade 62, and like the blade 61, is held in a form protruding in the moving path of the recording head. The blade 61, the cap 62, and the absorber 63 constitute a discharge recovery unit 64, and the blade 61 and the absorber 6
By 3, the water, dust, and the like on the ink ejection port surface are removed. Reference numeral 65 denotes a recording head which has an ejection energy generating means and ejects ink to a recording material facing the ejection port surface where the ejection ports are arranged to perform recording, and 66 denotes a recording head 65 mounted to move the recording head 65. It is a carriage for performing. The carriage 66 slidably engages with the 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 its adjacent area.

Reference numeral 51 is a paper feed section for inserting a recording material, and 52 is a paper feed roller driven by a motor (not shown). With these configurations, the recording material is fed to a position facing the ejection opening surface of the recording head, and is ejected to the ejection portion provided with the ejection roller 53 as the recording progresses.

In the above structure, when the recording head 65 returns to the home position due to the end of recording or the like, the head recovery section 64.
The carriage 62 is retracted from the movement path of the recording head 65, but the blade 61 is projected in the movement path. As a result, the ejection port surface of the recording head 65 is wiped. When the cap 62 comes into contact with the ejection surface of the recording head 65 to perform 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 at the same position as the above-mentioned position during wiping. As a result, even in this movement, the ejection port surface of the recording head 65 is wiped.

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

FIG. 4 shows an ink cartridge 4 containing ink to be supplied to the head through an ink supply tube.
It is a figure which shows an example of 5. Here, 40 is an ink bag containing the supply ink, and a rubber stopper 42 is provided at the tip thereof.
Is provided. By inserting a needle (not shown) into this stopper 42, the ink in the ink bag 40 can be supplied to the head. An ink absorber 44 receives the waste ink.

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 those in which they are integrated as shown in FIG. 5 are also preferably used. Be done.

In FIG. 5, reference numeral 70 denotes an ink jet cartridge in which an ink absorber impregnated with ink is stored, and the ink in the ink absorber is discharged from a head portion 71 having a plurality of orifices. It is configured to be ejected as an ink droplet. Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the cartridge with the atmosphere.

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

[0052]

Examples (Example 1) (Preparation of pigment dispersion liquid) Styrene-acrylic acid-ethyl acrylate copolymer 0.7 parts (acid value 174, average molecular weight 9000) Monoethanolamine 0.4 parts Ion-exchanged water 73.9 parts Ethylene glycol 5 parts The above components are mixed and heated to 70 ° C. in a water bath to completely dissolve the resin component. At this time, if the concentration of the resin to be dissolved is low, it may not be completely dissolved. Therefore, when dissolving the resin, a high-concentration solution may be prepared in advance and diluted to prepare a desired resin solution. .. Hostap to this solution
After adding 15 parts of erm Pink E (manufactured by Hoechst) and 5 parts of ethanol and premixing for 30 minutes, dispersion treatment was carried out under the following conditions.

Disperser Sand grinder (made by Igarashi Kikai) Grinding media Zirconium beads 1 mm diameter Grinding media filling rate 60% (volume) Grinding time 3 hours Further centrifugal separation treatment (12000 RPM, 20 minutes) is performed to remove coarse particles. To obtain a pigment dispersion.

(Preparation of Recording Liquid) The above pigment dispersion liquid 40 parts Glycerin 10 parts Ethylene glycol 10 parts Ethanol 4 parts Ion-exchanged water 36 parts The above components were mixed and stirred for 1 hour to obtain a recording liquid (A). (Example 2) (Preparation of pigment dispersion liquid) Acrylic acid-butyl acrylate-methyl methacrylate copolymer (acid value 80, average molecular weight 6700) 1 part Monoethanolamine 0.5 part Ion-exchanged water 72.5 parts Diethylene glycol 6 parts The above components are mixed and heated to 70 ° C. in a water bath to completely dissolve the resin component. Fuji Fast Red in this solution
Add 9900RM (Fuji Dye) 15 parts, 5 parts ethanol,
After premixing for 30 minutes, dispersion treatment was performed under the following conditions.

Disperser Sand grinder (made by Igarashi Machinery) Grinding media Glass beads 0.8 mm diameter Grinding media filling rate 50% (volume) Grinding time 3 hours Centrifugation treatment (20000 RPM, 20 minutes) was performed to remove coarse particles. It was removed to obtain a pigment dispersion.

(Preparation of Recording Liquid) The above pigment dispersion liquid 30 parts Thiodiglycol 4 parts 1,2,6-hexanetriol 5 parts Ethylene glycol 10 parts Isopropyl alcohol 4 parts Ion-exchanged water 47 parts The mixture was stirred for a time to obtain a recording liquid (B). (Example 3) (Preparation of pigment dispersion liquid) Styrene-maleic acid half ester-maleic anhydride copolymer (acid value 205, average molecular weight 7000) 0.6 part KOH 0.5 part ion-exchanged water 71.9 parts Ethylene glycol 5 parts The above components are mixed and heated to 70 ° C. in a water bath to completely dissolve the resin component. Add this solution to Hostaperm Red
After adding 15 parts of EG trans (manufactured by Hoechst) and 7 parts of ethanol and performing premixing for 30 minutes, a dispersion treatment was carried out under the following conditions.

Disperser Pearl mill (manufactured by Ashizawa) Grinding media Glass beads 1 mm diameter Grinding media filling rate 70% (volume) Discharge rate 80 ml / min. Centrifugation treatment (12000 RPM, 20 minutes) was performed to remove coarse particles. To obtain a pigment dispersion. (Preparation of Recording Liquid) Pigment Dispersion Liquid 35 parts Glycerin 12 parts Thiodiglycol 7 parts Ethylene glycol 5 parts Ethanol 5 parts Ion-exchanged water 36 parts The above components were mixed and stirred for 1 hour to obtain a recording liquid (C). .. (Comparative Example 1) Styrene contained in the dispersion of Example 1
A recording liquid (D) was obtained with the same formulation by changing the amount of the acrylic acid-ethyl acrylate copolymer to 5 parts, monoethanolamine to 2 parts, and ion-exchanged water to 68 parts. Comparative Example 2 The amount of the acrylic acid-butyl acrylate-methyl methacrylate copolymer contained in the dispersion liquid of Example 2 was 3 parts, monoethanolamine was 1 part, and ion-exchanged water was 70 parts. A recording liquid (E) was obtained by changing the same formulation. (Comparative Example 3) A recording liquid (F) was obtained with the same formulation by changing the amount of isopropyl alcohol and the amount of ion-exchanged water used in the preparation of the recording liquid of Example 3 to 0 parts and 51 parts, respectively. (Comparative Example 4) The amount of glycerin and thiodiglycol contained in the recording liquid of Example 3 was 0 part, and ion-exchanged water was 55 parts.
A recording liquid (G) was obtained with the same formulation by replacing the parts.

A modified inkjet printer BJ-130 (manufactured by Canon Inc.) which uses the recording liquids A to G as a printer and applies heat energy to eject ink.
The following evaluations (T1 and T2) were performed using.

[0059]

[Table 1] T1; Drive condition and ejection stability The drive voltage of the printer is set to 25V, 27V and 30V, and printing is performed at room temperature under two kinds of conditions of frequency 2KHz and 4KHz at each voltage. The presence or absence of non-ejection was observed and the ejection stability was evaluated.

⊚: The first character is ejected cleanly, and there is no ejection failure, chipping, or print disturbance during continuous printing.

Good: Characters are ejected neatly, but non-ejection is observed at several places in the solid printed portion.

Δ: Even in the character portion, non-ejection occurs when several characters are continuously printed.

X: Disturbance of ejection is remarkable from the first character, and the printed matter cannot be read.

T2: Recovery from clogging at the time of reprinting after long-term stoppage of printing After filling a printer with a predetermined recording liquid and continuously printing alphanumeric characters for 10 minutes, the printing is stopped and the cap is not removed. After leaving for 7 days in this state, a recovery operation for nozzle clogging was performed, and it was determined how many times it was possible to perform normal printing without fading or missing characters. In addition, the leaving condition is 60 ° C,
At 10 + 5% RH, the driving conditions were 2 KHz and 30V.

◯: Normal printing is possible with 1 to 5 recovery operations. Δ: Normal printing is possible with 6 to 9 recovery operations. ×: Normal printing is possible with 10 or more recovery operations.

[0066]

According to the present invention, it is possible to provide a magenta recording liquid suitable for a recording apparatus using various kinds of recording heads and using thermal energy, which has excellent robustness and color tone of a printed matter. Furthermore, it is possible to provide a recording method that is highly reliable and enables high-quality printing.

[Brief description of drawings]

FIG. 1A is a diagram showing the configuration of a recording head applicable to the implementation of the present invention. (B) is a diagram showing a configuration of a recording head applicable to the implementation of the present invention.

FIG. 2 is a diagram showing a configuration of a recording head applicable to implementation of the present invention.

FIG. 3 is a diagram showing an example of an inkjet recording apparatus incorporating the recording head as shown in the figure.

FIG. 4 is a diagram showing an example of an ink cartridge.

FIG. 5 is a diagram showing an example of an ink cartridge, which is integrated with a recording head.

Claims (15)

[Claims] 1. A recording liquid containing a pigment represented by the following general formula, a water-soluble resin and an aqueous medium, wherein the weight ratio of the pigment to the water-soluble resin is in the range of 15: 1 to 30: 1. Characteristic inkjet recording liquid. [Chemical 1] However, R: H, CH ₃ , Cl 2. The ink jet recording liquid according to claim 1, wherein the pigment is 3 to 30% by weight. 3. The ink jet recording liquid according to claim 2, which has a surface tension of 30 dyne / cm or more. 4. The ink jet recording liquid according to claim 1, wherein the aqueous medium is a polyhydric alcohol or its alkyl ether and an aliphatic monohydric alcohol. 5. The ink jet recording liquid according to claim 4, wherein the aliphatic monohydric alcohol has 1 to 3 carbon atoms. 6. The ink jet recording liquid according to claim 5, wherein the aliphatic monohydric alcohol is ethyl alcohol or isopropyl alcohol. 7. An aliphatic monohydric alcohol in an amount of 2 to 10% by weight.
The ink jet recording liquid according to claim 5, comprising. 8. The ink jet recording liquid according to claim 4, which contains 10 to 50% by weight of a polyhydric alcohol or an alkyl ether thereof. 9. The weight average molecular weight of the water-soluble resin is 3,000.
The ink jet recording liquid according to claim 1, which is ˜30,000. 10. The weight average molecular weight of the water-soluble resin is 500.
The ink jet recording liquid according to claim 9, which is 0 to 15,000. 11. The water-soluble resin is a styrene-acrylic acid copolymer, a styrene-acrylic acid-acrylic acid alkyl ester copolymer, a styrene-maleic acid copolymer, a 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, vinylnaphthalene-maleic acid copolymer, The inkjet recording liquid according to claim 1, which is a styrene-maleic anhydride-maleic acid half ester copolymer or a salt thereof. 12. A pigment and a water-soluble resin in a weight ratio of 15: 1.
To a 30: 1 ratio in the presence of an aqueous medium to form a pigment dispersion liquid, and the aqueous medium is further added. 13. The pigment is a quinacridone compound represented by the following general formula, and the water-soluble resin is a styrene-acrylic acid copolymer, a styrene-acrylic acid-acrylic acid alkyl ester copolymer, a 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 The method for producing an inkjet recording liquid according to claim 12, which is a copolymer, a vinylnaphthalene-maleic acid copolymer, a styrene-maleic anhydride-maleic acid half ester copolymer, or a salt thereof. [Chemical 2] However, R: H, CH ₃ , Cl 14. A recording liquid according to any one of claims 1 to 11 is subjected to thermal energy to be ejected as an ink droplet from an orifice and adhered to a recording material to perform recording. And an inkjet recording method. 15. The ink jet recording method according to claim 14, wherein the recording method is an on-demand type recording method.