JP2002060662A - Ink composition for ink jet and recording method therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink composition which is used in an on-demand ink jet recording system intended for high speed, high-reliability paint quality, and excellent weatherability, and provide a recording method with the same. SOLUTION: This ink composition for ink jet is used for forming record dots by jetting liquid ink drops onto a non-coated paper recording medium having a film thickness of 80-200 μm with an on-demand type ink jet printer and contains at least a pigment, water, and a glycol ether. The weight loss of the composition after 30 min at 25 deg.C/60%RH is 5-25%, and the amount of the residual ink composition after 24 h at 25 deg.C/60%RH is 10-40%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink composition used in an ink jet recording apparatus for performing high-speed recording on plain paper and a recording method.

[0002]

2. Description of the Related Art Conventionally, a water-soluble liquid ink composition has been widely used as an ink composition for ink jet recording. However, when printing is performed on plain paper such as copy paper generally used in offices, the printed ink spreads along the fibers of the paper, so that the dot shape becomes irregular and so-called bleeding occurs.

Various improvements have been made for the purpose of improving bleeding and drying properties. For example, in Japanese Patent Publication No. 60-34992,
It has been proposed that a large amount of surfactant lowers the surface tension of the ink and enhances the drying property. In addition, JP-A-58-1
JP 08271 discloses a method of recording using a hot-melt ink composition using a wax or the like which is solid at room temperature. U.S. Patent Nos. 4,391,369 and 4,484,948 describe ink compositions that provide good print quality regardless of paper quality.

[0004] On the other hand, in ink jet recording, a special substrate (for preventing excessive penetration and bleeding of ink droplets, realizing printing with high density and high saturation, and further improving water resistance and storage characteristics, is used). It was customary to use ink jet paper. There have been many reports on this, for example, USP 5,854,649, USP 5,8
No. 53,899, JP-A-11-192778, JP-A-11-129610, JP-A-11-078223, JP-A-11-078221, JP-A-11-03448
5, JP-A-11-028861, JP-A-11-020300, Patent 2,8
No. 45,832, Japanese Patent Application Laid-Open No. 11-506991, and the like, it is described that the ink adsorbability is improved by applying a specific water-soluble resin, for example, USP 5,516,364, JP-A No.
192775, JP-A-11-157207, JP-A-11-129606, JP-A-11-048604, JP-A-11-034481, JP2, 938,917
No., Patent 2,887,098, Patent 2,883,299, Patent 2,877,74
Publication No. 0 and the like describe that by containing a specific inorganic material such as clay and alumina, the ink adsorbability is similarly improved and high quality printing is performed.

[0005] In recent years, there has been an increasing demand for high quality printing on general paper (plain paper), not on special paper specially manufactured for ink jet printing. This is true not only for paper price reduction, but also for fields that were conventionally processed by other printing methods (such as offset, flexographic printing, ink printing, laser printers, non-impact printers such as thermal recording, and impact printers). This is a problem that is inevitably encountered when applying the ink jet recording method. Especially in the field of office work, which prints many office documents such as standard documents, slips, and forms at high speed, the use of plain paper and high-speed printing are indispensable requirements. The realization was extremely difficult with the recording method.

The water-soluble liquid ink composition is disclosed in
JP-A-2-233781 discloses a recording liquid containing a water-soluble organic solvent composed of diethylene glycol, glycerin and polyethylene glycol as a humectant in a recording liquid using a water-soluble medium and a dye. Patent No.
No. 2516218 discloses a recording method in which a composition containing a dye, a wetting agent and water has a sum of dynamic surface tension and viscosity of 42 to 49, and is used to print on paper having a Steckigt sizing degree of 10 or more. Is shown. In Japanese Patent No. 2801295,
A method is disclosed in which recording is performed on a recording material having a Stöckigt size of 0 to 15 by optimizing the dye concentration. Patent No.
No. 2529154 discloses an ink jet composition using a non-aqueous solvent whose evaporation rate is less than one tenth of butyl acetate.

On the other hand, in order to improve the weather resistance of the printed matter,
It is common to use a pigment as a colorant for the ink, and it is used as an ink for various printers such as a laser printer, a fusion transfer printer, a liquid inkjet printer, and a solid inkjet printer.

For example, with respect to pigment inks, see JP-A-3-3
No. 7278, JP-A-4-339871, JP-A-5-16343, JP-A-5-105832, JP-A-6-49400, JP-A-6-228479
JP-A-6-228480, JP-A-6-306319, JP-A-7
-109432, JP-A-7-196968, JP-A-7-278477,
JP-A-7-306319, JP-A-7-316479, JP-A-7-331
Many reports have been made, such as No. 141 and JP-A-8-295836. However, most of the widely used recording liquids for ink jet recording are recording liquids using an aqueous medium and a dye. This is because when a pigment is used, it is difficult to mix constituent materials so that the dispersion of the pigment can be kept stable, and it is difficult to store the recording liquid stably for a long period of time.

As described above, unlike a recording liquid using a dye which is soluble in an aqueous medium, a recording liquid using a pigment is insoluble in an aqueous medium and is in a solid state. Clogging easily occurs, and a large amount of a humectant such as polyalkylene glycol or glycerin is required. For example, Japanese Patent Application Laid-Open No. Hei 3-154664 discloses a recording liquid using a pigment, but it has been stated that it is preferable to use 30 to 80 parts of a humectant with respect to 100 parts of water.
Although a method of adding a large amount of a humectant to prevent pigment aggregation has been attempted, the viscosity of the recording liquid is increased and the ejection property is reduced. Japanese Patent Publication No. 5-30870 discloses an aqueous pigment ink containing trimethylpentanediol monoisobutyrate and ethylene glycol monobutyl ether in order to improve the drying resistance of the pen tip without increasing the viscosity. Japanese Patent Publication No. 6-21250 discloses a recording liquid having a high fixing speed by containing a dialkyl ether. In JP-A-11-228884, in 100 g of an ink composed of a pigment, a humectant, and an aqueous medium, the amount of residual moisture is
0.5 to 10 g.

[0010]

As described above, when a water-based ink is used for printing, it is difficult to print on a recording medium having no ink absorption, and even when a special paper is used, a large size ink is required. An ink drying device is required. In addition, high-definition printing is difficult due to the problem of bleeding, and the resolution is limited, so that its use is limited. Solvent inks may be used due to the advantage of quick drying, but are not desirable in terms of flammability and environmental safety. Hot-melt oil-based inks are capable of high-speed printing, but due to the nature of the inks, the printing dots are thick and have a thickness of about 10 to 20 microns, resulting in low abrasion resistance and difficulty in obtaining reliability after printing.

An ink jet recording system using an organic pigment as a coloring agent has many advantages over an ink jet recording system using a dye, particularly in terms of weather resistance.
Equipment, general household printers, facsimile and other office printers as well as indoor and outdoor posters, large signs, cars,
It is expected to be applied to decoration of glass, elevators, walls and buildings, and printing on fabric. However, the problem that high-reliability printing quality cannot be obtained as described above has been a bottleneck in commercialization.

It is an object of the present invention to provide an ink composition for an ink jet printer which gives good quality recorded matter to uncoated paper by drying at a high speed, and a printing mechanism thereof. A further important object of the present invention is to provide a pigment ink composition for a high-speed inkjet printer, which has a sufficient ejection stability and is sufficient for ejecting ink droplets from fine nozzles.

[0013]

The gist of the present invention to solve the above problems is to form recording dots by ejecting ink droplets onto an uncoated paper recording medium having a thickness of 80 to 200 μm by an on-demand type ink jet printer. The ink composition for ink jet used for the ink composition contains at least a pigment, water and a glycol ether, and the weight loss rate of this ink composition at 25 ° C./60 RH% is 5 to 25% of the total amount of the ink in 30 minutes, and In 24 hours,
The remaining amount was set to be 10 to 40% of the total amount of the ink.

The above ink composition for ink-jet printing comprises:
The viscosity at 5 ° C. is 3-6 mPa.s and the surface tension is 30
４５45 mN / m, preferably when the mixing ratio of water and glycol ether is changed from 30: 1 to 6: 1, the change in viscosity is 1 mPa.s, and the change in surface tension is 6 mN / m or less. Good to be.

The glycol ether contained in the ink composition is preferably an ethylene glycol ether and / or a propylene glycol ether, and preferably contains 1 to 10% by weight.

The above ink composition can obtain good print quality when printed at a recording speed at which the relative speed between the nozzles and the paper is 10 ips or more.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The weight reduction and residual amount of an ink composition, which is a feature of the present invention, will be described below.

Conventionally, various methods have been devised in ink jet recording in order to achieve both high drying properties of prints and clogging due to drying of nozzle portions. For example, by mixing an appropriate amount of a high boiling solvent called a wetting agent,
Even after the main solvent (e.g., water) evaporates, the remaining solvent prevented clogging of the nozzle. That is, it is well known in the art to achieve desired characteristics by appropriately controlling the evaporation rate. However, as one of the other problems in the ink jet printing, a phenomenon in which ejection is delayed immediately after the start of printing and sufficient printing cannot be performed was temporarily recognized (a delay phenomenon at the beginning of printing). FIG. 1 shows a problem caused by printing of the conventional ink. A printing delay is recognized in a portion surrounded by a circle in the figure. Although many materials have been selected and individually dealt with with respect to this phenomenon, a sufficient study has not yet been made particularly in the field of high-speed recording on plain paper which is the object of the present invention.

The present inventors have studied this phenomenon and the characteristics of the ink composition in various ways.

As a result of the study, it was found that the amount of evaporation after leaving for a long period of time, which has conventionally been a problem with the wetting agent, was shorter (t in the figure).
It was found that when the reduction rate D at the time a) was equal to or more than a certain value, a remarkable delay phenomenon in the initial stage of printing occurred. Further, when an excessive amount was added for the purpose of suppressing evaporation, the residual amount R in a long time tends to be unnecessarily large. On the other hand, the ink composition of the present invention maintains both the initial evaporation amount and the residual ratio after 24 hours when the decrease substantially reaches an equilibrium state, so that the high dryness of the printed matter and the drying of the nozzle portion are maintained. And found that the printed matter had moderate gloss and excellent finger touch. Then, as shown in FIG. 2, it was clarified that the printing of the ink composition of the present invention did not cause a delay in the initial printing.

FIG. 3 is a conceptual diagram showing this. The figure shows the weight loss of the two ink compositions from 100%, wherein curve 1 corresponds to the ink of the present invention and 2 corresponds to the conventional ink. As in the case of the conventional ink, simply mixing a normal high-boiling solvent has no effect of suppressing the initial evaporation (almost equal to the evaporation rate of the main solvent, for example, water), and the excess is more than the intended reduction rate. It was easy to evaporate (D ₂ in the figure). On the other hand, in the ink of the present invention, this is in an appropriate range (D ₁ in the figure), so that the delay phenomenon at the beginning of printing can be effectively suppressed, and the remaining amount R ₁ can be reduced to an appropriate range. That is, it should be noted that the present invention is based on the viewpoint of recording at high speed on uncoated paper, which is completely different from the conventional addition of a wetting agent. Specifically, when ta = 30 minutes, 5% ≦ D ₁
≦ 25%, tb = 24h, 10% ≦ R ₁ ≦
40% (25 ° C., 60 RH%). Note that the lower limit of the reduction rate is 60%, which corresponds to the ink remaining rate of 40%, and is the limit at which the amount of ink remaining for a long time becomes excessive.

The present invention has also found the types of compounds sufficient to achieve this object and the optimum addition range thereof.
It is not clear why the ejection delay is correlated with the weight loss rate. For example, as shown in FIG. 4, a highly evaporable component (usually, It is conceivable that the main solvent, for example, water, evaporates to a small extent, causing changes such as an increase in the viscosity of the ink, which hinders ejection. In the figure, reference numeral 3 denotes a cross section of the nozzle, 4 denotes the ink in the head, and 5 denotes a high-viscosity (or characteristic-changed) portion of the surface of the ink.

FIG. 5 shows examples of specific experimental results of the ink composition of the present invention and a conventional ink composition. As described above, it can be clearly discriminated that the weight reduction rate of the ink composition of the present invention is limited to a specific range different from that of the conventional ink composition.

Regarding the remaining amount of the ink composition of the present invention,
This will be described in detail below.

The ink-jet ink composition of the present invention is left at 25 ° C./60 RH% in a windless state for 24 hours, and the remaining amount is 10 to 40% of the total amount of the ink, that is, the reduction rate is 60 to 90%. Is the feature. This remaining amount is an index indicating the drying of the ink. In general, inks having the same value are easily dried. In order to improve the intermittent printing characteristics, it is desirable that this value is large and that drying is difficult. However, if the remaining amount exceeds 40% of the total amount of ink, the drying property of the ink after recording is insufficient, and when printed on plain paper at high speed, the touch feeling is poor and the quality of the printed matter is deteriorated only by finger contact. . On the other hand, from the standpoint of fixability and fastness of printing, it is desirable that the remaining amount of ink is small. However, if it is less than 10%, ejection becomes extremely unstable, and the printed matter is less glossy and poor in quality. The ink composition of 10 to 40% achieves both high drying property of the printed matter and clogging due to drying of the nozzle portion, and furthermore, the printed matter has moderate gloss and excellent finger touch.

As important characteristics for achieving the object of the present invention, the viscosity at 25 ° C. is 3 to 6 mPa.s, and the surface tension is 3
A method of adjusting the pressure to 0 to 45 mN / m is exemplified. Polyhydric alcohols such as (poly) alkylene glycols such as polyethylene glycol and glycerin have low evaporation rates.
It is effective as a wetting agent. Alkylene glycols are particularly desirable.

Specifically, if the viscosity is less than 3 mPa · S, an appropriate ink amount and dot diameter cannot be obtained, and
If the viscosity exceeds S, it is difficult to perform stable inkjet recording. Also, if the surface tension is less than 30 mN / m, the ink penetrates into the recording medium at a high speed, causing set-off (ink seepage to the back side of the recording paper), and transferring over 45 mN / m (contamination of the ink contact portion). Is not suitable for high-speed printing.

As a component for achieving the object of the present invention, it is desirable to contain (poly) alkylene glycol in an amount of 1 to 50% by weight. If it is less than 1% by weight, the increase in the viscosity of the main component water is small, and if it exceeds 50% by weight, the viscosity of the ink is significantly increased and the discharge amount of the ink is reduced, so that the print density is lowered. And the drying quality is deteriorated, and the printing quality is lowered.

Further, it has been found that glycol ether is suitable as a component for achieving the object of the present invention.
In general, glycol ethers are added for the purpose of preventing the tip of a ballpoint pen or the nozzle of an ink jet from drying without increasing the viscosity of the recording liquid due to its low viscosity.
In addition, the surface tension can be adjusted so that the ink composition can be jetted without significantly causing foaming of the ink composition as compared with ethers of a surfactant. For example, as described above, a highly evaporable component (usually a main solvent, for example, water) evaporates, albeit slightly, from the ink composition in the portion of the open nozzle that comes into contact with the atmosphere, increasing the viscosity of the ink and increasing the surface tension. It is conceivable that a change such as lowering the ink discharge occurs, and this may hinder ejection. However, when the mixing ratio of water and glycol ether is changed from 30: 1 to 6: 1, this phenomenon can be avoided by changing the viscosity change to 1 mPa.s and the surface tension change to 6 mN / m or less. Was found.

Particularly preferred glycol ethers are ethylene glycol ethers such as methyl glycol, methyl diglycol, methyl triglycol, methyl polyglycol, butyl glycol, butyl diglycol, butyl triglycol, isobutyl glycol, and the like (all manufactured by Nippon Emulsifier). And methyl propylene glycol, methyl propylene diglycol, methyl propylene triglycol, propyl propylene glycol, propyl propylene diglycol, butyl propylene glycol,
It is desirable to contain 1 to 10% by weight of an ether selected from propylene glycol-based ethers such as butyl propylene diglycol and phenyl propylene glycol (all manufactured by Nippon Emulsifier). If it exceeds 10% by weight, the surface tension is reduced, and the print quality is reduced.

In addition, for example, ethylene glycol, propylene glycol, diethylene glycol and dipropylene glycol, triethylene glycol, pentamethylene glycol, polyethylene glycol (all manufactured by Wako Pure Chemical Industries) and the like can be used.

Glycerin may be added for the purpose of further improving the dischargeability. Urea is also effective because it prevents drying.

Specifically, PEG200, PEG300,
PEG400, PEG600, PEG1000, PEG
1540, PEG2000, PEG4000, PEG1
1000, PEG 20000, Uniol D250, D
400, D700, D1000, D1200, D200
0, D3000, D4000, TG330, TG100
0, TG3000, TG4000, Unilube 50MB
-2, 50MB-5, 50MB-11, 50MB-2
6, 50MB-72, 50MB-168, 50D-2
5, 75DE-25, 75DE-60, 75DE-17
0, 75DE-250, 75DE-2620, 75DE
-3800, 75DE-5000, etc. (Nippon Oil & Fat).

Further, at least one of these, or 2
A mixture of more than one species can be used.

Particularly, ethylene glycol is preferable because it has a low viscosity and does not increase the viscosity of the ink composition even when added in a required amount, and is excellent in the effect of suppressing the weight loss rate.

A water-soluble solvent may be added for improving the characteristics.

For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, isopropanol and lower alcohols, acetates such as ethylene glycol, propylene glycol, diethylene glycol and dipropylene glycol, thiodiglycol, N-methyl- Nitrogen-containing compounds such as 2-pyrrolidone, 1,3-dimethylimidazolidinone, amino alcohol, sodium lactate, DMSO, polyoxyethylene alkylphenol, and polyoxyethylene fatty acid ester may be used alone or as a mixed solvent. In addition, polyethylene glycol bisphenol A ether, polypropylene glycol bisphenol A ether, polyethylene glycol monomethyl ether, polyethylene glycol glyceryl ether, special polyethylene glycol, polyethylene glycol dimethyl ether (Nippon Oil & Fats) and the like can also be used.

The pigment which is an essential component for achieving the object of the present invention is preferably a pigment which is well dispersed in the above-mentioned vehicle and has excellent weather resistance. The color development (color density per added concentration) of the pigments used particularly in the present invention is not always high, and in addition, it is difficult to produce a uniform fine particle dispersion. Therefore, it has not been practically used as an inkjet ink.
Although not particularly limited, organic or inorganic pigments having the following numbers described in, for example, a color index can be used in the present invention.

As a red or magenta pigment, Pigmen
t Red 3, 5, 19, 22, 31, 38, 43, 48: 1, 48: 2, 48:
3, 48: 4, 48: 5, 49: 1, 53: 1, 57: 1, 57: 2, 58:
4, 63: 1, 81, 81: 1, 81: 2, 81: 3, 81: 4, 88, 10
4, 108, 112, 122, 123, 144, 146, 149, 166, 168, 16
9, 170, 177, 178, 179, 184, 185, 208, 216, 226, 25
7, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, P
pigment Orange 13, 16, 20, 36, and blue or cyan pigments include pigment blue 1, 15, 15: 1, 15: 2, 15: 3, 1
5: 4, 15: 6, 16, 17-1, 22, 27, 28, 29, 36, 60, as a green pigment, Pigment Green 7, 26, 36, 50, as a yellow pigment, Pigment Yellow 1, 3, 12, 13, 14, 17, 3
4, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 10
9, 110, 137, 138, 139, 153, 154, 155, 157, 166, 16
7, 168, 180, 185, 193, as the black pigment, Pigment Bla
ck 7, 28, 26, etc. can be used according to the purpose.

Specific examples of trade names are, for example, Chromofine Yellow 2080, 5900, 5930, AF-1300, 2700
L, Chromo Fine Orange 3700L, 6730, Chromo Fine Scarlet 6750, Chromo Fine Magenta 6880, 68
86, 6891N, 6790, 6887, Chromofine Violet
RE, Chromo Fine Red 6820, 6830, Chromo Fine Blue HS-3, 5187, 5108, 5197, 5085N, SR-5020, 50
26, 5050, 4920, 4927, 4937, 4824, 4933GN-EP, 494
0, 4973, 5205, 5208, 5214, 5221, 5000P, Chromofine Green 2GN, 2GO, 2G-550D, 5310, 5370, 6830,
Chromo Fine Black A-1103, Seika Fast Yellow 10GH, A-3, 2035, 2054, 2200, 2270, 2300, 2400
(B), 2500, 2600, ZAY-260, 2700 (B), 2770, Seika Fast Red 8040, C405 (F), CA120, LR-116, 1
531B, 8060R, 1547, ZAW-262, 1537B, GY, 4R-4016,
3820, 3891, ZA-215, Seika Fast Carmin 6B1476T
-7, 1483LT, 3840, 3870, Seika Fast Bordeaux 10B
−430, Seika Light Rose R40, Seika Light Violet B800, 7805, Seika Fast Maroon 460N, Seika Fast Orange 900, 2900, Seika Light Blue C71
8, A612, cyanine blue 4933M, 4933GN-EP, 4940, 49
73 (Daiichi Seika Kogyo), KET Yellow 401, 402, 40
3, 404, 405, 406, 416, 424, KET Orange 501, KET Re
d 301, 302, 303, 304, 305, 306, 307, 308, 309, 31
0, 336, 337, 338, 346, KET Blue 101, 102, 103, 10
4, 105, 106, 111, 118, 124, KET Green 201 (all manufactured by Dainippon Ink and Chemicals), Colortex Yellow 301, 314, 31
5, 316, P-624, 314, U10GN, U3GN, UNN, UA-414, U2
63, Finecol Yellow T-13, T-05, Pigment Yellow170
5, Colortex Orange 202, Colortex Red 101, 103, 11
5, 116, D3B, P-625, 102, H-1024, 105C, UFN, UC
N, UBN, U3BN, URN, UGN, UG276, U456, U457, 105C, U
SN, Colortex Maroon601, Colortex BrownB610N, Color
tex Violet600, PigmentRed 122, Colortex Blue516, 5
17, 518, 519, A818, P-908, 510, Colortex Green40
2,403, Colortex Black 702, U905 (manufactured by Sanyo Dye), Lionol Yellow1405G, Lionol Blue FG7330, FG73
50, FG7400G, FG7405G, ES, ESP-S (manufactured by Toyo Ink), Toner Magenta E02, Permanent RubinF6B, Tone
r Yellow HG, Permanent Yellow GG-02, Hostapeam Bl
ueB2G (made by Hoechst Industries), carbon black # 2600, # 2400, # 2350, # 2200, # 1000, # 99
0, # 980, # 970, # 960, # 950, # 850, MCF88, # 75
0, # 650, MA600, MA7, MA8, MA11, MA100, MA100R, MA
77, # 52, # 50, # 47, # 45, # 45L, # 40, # 33, # 3
2, # 30, # 25, # 20, # 10, # 5, # 44, CF9 (all manufactured by Mitsubishi Chemical) and the like.

A dispersion in which the pigment is previously dispersed in water or a solvent at a high concentration may be used. For example, MICROPIGMO
WMBK-5, WMBE-5, WMRD-5, WMYW-5, AMBK-2, AMYW-2, A
MBE-4 (all manufactured by Orient Chemical), JA Black 25W, GA Bl
ACK 2821, GA Yellow 1, GAMagenta1, GA Cyan 2 (Made by Okuni Pigment) CAB-O-JET200, CAB-O-JET300 (Made by Cabot Specialty Chemicals), etc., and high pigment concentration of 10% by weight or more Particularly preferred are those dispersed in

The appropriate amount of addition is 2 to 10% by weight of the pigment concentration. If the amount is less than 2% by weight, the image quality is degraded. In addition, two or more colorants can be mixed and used as needed for color adjustment and the like. In order to further develop functionality in the ink composition of the present invention, light stabilizers, surface treatment agents, surfactants, viscosity reducing agents, antioxidants, antioxidants, crosslinking accelerators, oxygen absorbers, plasticizers , A preservative, a rust preventive, an evaporation promoter, a pH adjuster, a defoamer, a humectant, a dispersant, a dye, and the like. Mixing and dispersing the above-mentioned vehicle, pigment and other components include a stirrer, a bead mill,
Although a homogenizer is optimal, various known stirring, pulverizing or dispersing devices can be used without any particular limitation.

The paper used for the purpose of the present invention belongs to a part of uncoated paper, special printing paper and information paper. 80
Uncoated paper of ２００200 μm is desirable. As a classification of paper, a classification method used in production statistics of the Ministry of International Trade and Industry is often used. According to this, printing information paper, packaging paper, sanitary paper, and miscellaneous paper are roughly classified, and the printing information paper is divided into uncoated paper, lightly coated paper, coated paper, special printing paper, and information paper. is there. The composition of paper varies widely, depending on the pulp material, the type and amount of paint, and the production method, and there are many methods for evaluating and classifying paper. For example, paper density, thickness, front / back difference, vertical / horizontal (making direction),
There are pore porosity, air permeability, water absorption / oil absorption, size, surface roughness, gloss, pH, surface strength, peel strength, stiffness, folding strength, chargeability, etc., each of which affects print quality. The inventor paid attention to the thickness of paper as a method for generally defining paper in the field intended by the present invention.

As the paper of the present invention, for example, special printing paper such as grade printing paper, intermediate printing paper, lower grade printing paper, thin printing paper, finely coated printing paper, color high quality paper, foam paper, PPC
There are papers, other information papers, etc.Specifically, there are the following papers and various modified / processed papers using these,
The present invention is not particularly limited to these. High quality paper and color high quality paper, recycled paper, copy paper / color, OCR paper, carbonless paper / color, YUPO 60, 80, 110
Micron, synthetic paper of Yupocoat 70, 90 microns, etc.,
Other single-sided art paper 68 kg, coated paper 90 kg, foam mat paper 70, 90, 110 kg, foamed PET 38
Micron, Mitsuori-kun (Kobayashi Recording Paper), OK fine paper, New OK fine paper, sunflower, phoenix,
OK Royal White, export high quality paper (NPP, NCP,
NWP, Royal White) OK book paper, OK cream book paper, cream fine paper, OK map paper, OK Ishikari, cucumber, OK foam, OKH, NIP-N
(Shin Oji Paper), Kim Wang, Toko, export fine paper, special demand fine paper, book paper, book paper L, light cream book paper, small textbook paper, continuous slip paper, fine NIP paper, silver ring, gold Sun, Kimyang (W), bridge, capital, silver ring book, harp, harp cream, SK color, securities paper,
Opera cream, opera, KYP chart, Sylvia H
N, Excellent Form (Nippon Paper), Pearl,
Kinbishi, Uscream fine paper, special book paper, super book paper, book paper, diamond form (Mitsubishi Paper),
Carpet V, carpet SW, white elephant, luxury publishing paper, cream carpet, cream elephant, securities and voucher paper, book paper, map paper, copy paper, HNF (Hokuetsu Paper Mills), telephone book cover , Book Paper, Cream Shiorai, Cream Shiorai Medium Rough, Cream Shiorai Large Rough, DSK (Daishowa Paper), Sendai MP Fine Paper, Kinkoe, Thunderbird Fine, Kakegami, Shikishi Base Paper, Dictionary Paper, Cream book, white book, cream fine paper, map paper, continuous slip paper (above Chuetsu pulp), OP Kinzakura (Chuetsu), gold sand, reference book paper, exchange certificate paper (white), form printing paper, KRF, white foam , Color Form, (K) NIP, Fine PPC (Kishu Paper), Taiou, Bright Form, Kant, Kant White, Dante, CM Paper, Dante Comics, Heine, Paperback Book Paper Heine S, New AD paper,
Utrilo Excel, Excel Super A, Kant Excel, Excel Super B, Dante Excel, Heine Excel, Excel Super C, Excel Super D, AD
Excel, Excel Super E, New Bright Foam, New Bright NIP (from Daio Paper), Sun Ring,
Moon Ring, Unling, Galaxy, Baiyun, Weiss, Moon Ring Ace, Baiyun Ace, Uncen Ace (Nippon Paper Industries), Taiou, Bright Foam, Bright Nip (Nagoya Pulp),
Peony A, Golden pigeon, Tokupei, Shiropeon A, Shiropeony C, Ginbato, Super Shiropeony A, Pale cream white peony, Tokushiro medium paper, Shiro pigeon,
Super medium paper, blue pigeon, red pigeon, golden pigeon M Snow Vision,
Snow Vision, Golden Pigeon Snow Vision, White Pigeon M, Super DX, Hamanasu O, Red Pigeon M, HK Super Printing Paper (Honshu Paper), Star Linden (A / AW), Star Elm, Star Maple, Star Laurel, Star Poplar, MOP, Star Cherry I, Cherry I Super,
Cherry II Super, Star Cherry III, Star Cherry IV, Cherry III Super, Cherry IV
Super (Maruzumi Paper), SHF (Toyo Pulp), TRP (Tokai Pulp).

As a recording medium, JIS P8122
Size degree 2 according to "Test method for paper Sekihito sizing degree"
The above sheets can be used without any particular limitation.

Further, high quality paper and color high quality paper, Xerox
4024, inkjet plain paper and special paper, recycled paper, slip paper, and the like. Paper having a film thickness of 95 to 115 μm, which is widely used as ordinary plain paper, is particularly preferred for the purpose of the present invention.

The recording medium to which the present invention is applied is preferably uncoated paper. For example, in terms of the ratio of the elemental components of the paper, the number of aluminum and silicon elements is 150 and 200 or less, respectively, for 100 carbon elements. It is desirable that Although the surface roughness coefficient is not strict, for example, paper having an average surface roughness Rz of 10 μm or more substantially corresponds to this.

The printing speed of the printer in the field targeted by the present invention is markedly higher than that of the conventional ink jet recording. Although there is no clear limitation on the speed, for effective use of the ink composition of the present invention, a recording speed at which the relative speed between the nozzle and the paper is 10 ips (inch / s) or more is particularly preferable. To record fast,
It is necessary to fix (set) the ink droplets immediately after they adhere on the recording medium. In the case where the ink droplets are insufficient, the ink droplets are transferred to the back surface of another sheet on which the ink is deposited. Fatal problems such as sticking to the roll and disturbed recording dots may occur. To achieve a recording speed of 10 ips, for example, it is necessary that the recording be fixed within about 1 s after the recording. That is, according to the present invention, about 1 s
Records can be handled practically within (touching, etc.)
Becomes

There are various types of recording heads or recording methods for on-demand type ink jet recording using piezoelectric elements, such as line type recording, serial type recording, and transfer type (shuttle type) recording. Used without particular limitation. In either case, the relative movement speed between the nozzle and the paper (recording medium) is 10 ips or more. For example, when the head portion is fixed and only the paper moves as in line-type recording, the paper movement speed (paper Feed speed) corresponds to the above-mentioned relative speed, and in the case of serial recording, that is, when the head moves perpendicularly to the paper feed direction and sequentially records and the paper is intermittently fed, the head moving speed (carriage speed) is Corresponds to relative speed. In the case of a transfer type in which the paper is installed on a rotating drum or the like and records on it, or the recording type is temporarily recorded on the drum and then transferred to the paper, the speed at which the relative position between the moving paper or the drum surface and the nozzle changes I understand. In any case, the printing speed is directly related to the nozzle ejection frequency and the printing resolution. For example, the paper feed speed of line type recording or the head moving speed of serial type (that is, recording speed) V
Is given by V according to the ink droplet ejection frequency f and the recording resolution R.
= F × R. In the conventional recording at 5 ips or less (usually 1 ips or less), many ink compositions reported conventionally can be applied as they are. The invention is at least 5ip
It can be effectively used in high-speed recording of s or more, particularly preferably 10 ips or more.

The preparation of high quality ink jet inks requires a balance of many important factors. Although these requirements are complex and cannot always be clearly quantified for the inks of the present invention, the inks of the present invention satisfy some well-known requirements for application in ink jet printers. That is, the ink has sufficient stability at room temperature, and has high reliability in storage before printing and image quality after printing. After adhesion and curing on a recording medium, it has sufficient transparency and saturation and forms a uniform thin film to give a printed matter of good image quality. It is necessary that the composition does not cause offset in a state where printed matter is stacked, and that the composition is highly safe in consideration of the environment and the human body.

Further, the composition can be used in a known ink jet printer such as an office printer, a printer used for industrial marking, a wide format printer, which ejects ink droplets only when printing is necessary. It can also be used for plate and plate making printers, label printers and all types of high speed printers having this typical operation. Because high-speed drying is possible,
As the recording medium, in addition to the above-mentioned paper, plastic films, capsules, gels, metal foils, glass, acrylic plates, wood, natural fibers, synthetic fibers, and cloths made of blends thereof can be used. As long as non-contact printing is possible, a wide variety of media shapes can be used, and the present invention is not limited to these.

Next, the present invention will be described in detail with reference to examples, but it should not be construed that the invention is limited thereto. [Examples 1 to 6] Purified water of 47% by weight, polyethylene glycol having an average molecular weight of 200 (manufactured by Wako Pure Chemical Industries, trade name: polyethylene glycol 200) at 15% by weight, and dipropylene glycol (manufactured by Wako Pure Chemical Industries) at 38% by weight. % Of each of the alkylene glycol alkyl ethers shown in Table 1 in an amount of 1 to 10% by weight, and a black pigment dispersion (CAB-O-J, manufactured by Cabot Specialty Chemicals, Inc.) as a pigment.
ET300) 10 weight percent mixed with each other,
A homogenizer (HG3 manufactured by Hitachi Koki Co., Ltd.)
Using 0), the mixture was dispersed at 2,000 rpm until a homogeneous mixture was obtained, followed by filtration to remove impurities and the like, to obtain four homogeneous ink compositions. Table 1 shows the results.

[0053]

[Table 1]

The weight loss and the residual amount of the ink composition are as follows:
First, two 50 μl ink droplets were formed on a glass plate with a micropipette, and the weight of the ink composition was immediately measured.
After storing for 0 minutes at 25 ° C./60 RH% in a windless state, the weight was measured again and the reduction rate was calculated to be 5 to 20%. After 24 hours, the residual amount was measured again and the residual ratio was calculated.

When the viscosity was measured using a rotational viscometer (EDM model manufactured by Tokimec), the viscosity was 6 to 8 mPa · s at 25 ° C.
Met. The surface tension was measured using an automatic surface tensiometer (CVBP-Z model manufactured by Kyowa Interface Science Co., Ltd.).
It was 48 mN / m.

The ink composition was sealed in a test tube of 12 mmφ and left at room temperature for 3 days to separate the pigment (the separation ratio was%).
Observation) showed no separation.

This ink was put into an ink jet printer (manufactured by Hitachi Koki, model name: JOLT SJ01A), and it was confirmed that all the ink was ejected from 96 nozzles.
When the nozzle was left for 4 hours and the injection was performed again, the number of nozzles that could not be obtained was examined. As a result, it was confirmed that all 96 jetted without any problem, and that the ejection was stable after standing.

Offset of ink after printing on 70 kg paper and 135 kg paper (Kobayashi Recording Paper, NIP paper)
Transfer and water resistance were evaluated. In the table, ◎ means excellent, は means good, and × means unusable. It was found that the ink composition of Example 1 was able to print well on plain paper. Example 7 86% by weight of purified water having the composition shown in Table 1, 2% by weight of diethylene glycol monomethyl ether, 5% by weight of 2-pyrrolidone, N, N-
Dimethylethanolamine (all manufactured by Wako Pure Chemical Industries)
By weight, the pigment dispersion was mixed at a concentration of 30% by weight with respect to the total amount, and a homogeneous ink composition was obtained in the same manner as in Example 1. Table 1 shows the results of the evaluation performed in the same manner as in Example 1.

The weight loss rate is 25% and the residual rate is 1
The viscosity at 0% and 25 ° C. was 1.8 mPa · s, and the surface tension was 50 mN / m at room temperature. No pigment separation was observed. It was confirmed that the ejection was stable even after standing. It was found that good printing was possible on plain paper. [Comparative Examples 1 to 6] 10% by weight of purified water, 42% by weight of ethylene glycol, and 48% by weight of dipropylene glycol (manufactured by Wako Pure Chemical Industries) having the composition shown in Table 1, and various alkylenes shown in Table 1 Glycol alkyl ethers are each added in an amount of 1 to 10% by weight, and a black pigment dispersion (CAB-O-JET300, manufactured by Cabot Specialty Chemicals) 1 is further used as a pigment.
Ink analog 6 mixed with 0% by weight of each
Seeds were manufactured, and the same measurements and evaluations as in Example 1 were performed. In each case, the weight loss rate was 4% or less, and the residual rate was 40% or more, which was unsuitable for plain paper printing. Examples 8 to 14 60% by weight of purified water having the composition shown in Table 2, 35% by weight of ethylene glycol, 5% by weight of propylene glycol monomethyl ether acetate, and diethylene glycol monobutyl ether and triethylene glycol monobutyl ether (all of which 2 to 10% by weight of each of the pigments, and the pigment dispersion was mixed at a concentration of 10% by weight with respect to the total amount, and a homogeneous ink composition was prepared in the same manner as in Example 1. Eight species were obtained. Example 1
Table 2 shows the results of evaluation in the same manner as in the above.

[0060]

[Table 2]

The weight reduction rate was 10 to 14 percent, the residual rate was about 40 percent, the viscosity at 25 ° C. was 3 to 5 mPa · s, and the surface tension was 33 to 42 mN / m at room temperature. When the mixing ratio of water and glycol ether was changed from 30: 1 to 6: 1, the change in viscosity was 1 mPa · s,
The change in surface tension was within 6 mN / m. No pigment separation was observed. It was confirmed that the ejection was stable even after standing. It was found that good printing was possible on plain paper. [Comparative Examples 7 to 12] Purified water 80% by weight, ethylene glycol 10% by weight, propylene glycol monomethyl ether acetate 10 having the composition shown in Table 2
2 to 10% by weight of ethylene glycol monoisobutyl ether (manufactured by Wako Pure Chemical Industries, Ltd.), and the pigment dispersion was mixed at a concentration of 30% by weight with respect to the total amount. Example 1
In the same manner as in Example 1, four homogeneous ink analogs were obtained. Table 2 shows the results of evaluation by the same method as in Example 1 in combination with the two types of commercially available products A and B.

The weight loss rate was 26 to 2 in Comparative Examples 7 to 10.
8%, the residual rate is less than 10%, and Comparative Examples 11 and 12 have a weight loss rate of 5,
12%, the residual rate was 40% or more. 25 ° C
Is about 3-6 mPa · s and the surface tension is 25 at room temperature.
３５35 mN / m. When the mixing ratio of water and glycol ether was changed from 30: 1 to 6: 1, the change in viscosity was within 1 mPa · s, but the change in surface tension was 7 mN / m. No pigment separation was observed. After standing, the nozzle dried and the ejection was unstable. Comparative Examples 11 and 12
Showed stable ejection but was unsuitable for plain paper printing.

[0063]

The ink composition of the present invention for ink-jet printers has improved ink quick-drying and storage stability, which have conventionally been problems with aqueous inks. Further, since a pigment is used as a coloring agent, colorant dispersion stability is improved. The ink has both high performance and jet characteristics, and is superior in weather resistance to inks containing a dye as a main colorant, thereby satisfying demands for high speed and low cost, and making it possible to produce inks with a wide range of uses.

[Brief description of the drawings]

FIG. 1 is a photograph showing a printing state of a conventional ink composition.

FIG. 2 is a photograph showing a printing state of the ink composition of the present invention.

FIG. 3 is a diagram illustrating the concept of ink weight reduction.

FIG. 4 is a cross-sectional view showing a state of ink near a nozzle.

FIG. 5 is a graph showing the weight reduction rate of the ink composition of the present invention and the conventional ink composition.

[Explanation of symbols]

1 is an ink composition of the present invention, 2 is a conventional ink composition,
Reference numeral 3 denotes a cross section of the nozzle, 4 denotes the ink in the nozzle, and 5 denotes a high-viscosity portion of the surface of the ink.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C056 FC02 2H086 BA02 BA21 BA52 BA53 BA55 BA60 BA61 BA62 4J039 AE07 BA12 BC13 BC14 BE01 BE28 CA06 EA10 EA34 EA44 EA48 GA24

Claims (6)

[Claims] 1. An ink-jet ink composition used for forming recording dots by jetting ink droplets onto an uncoated paper recording medium having a thickness of 80 to 200 μm by an on-demand type ink-jet printer, comprising at least a pigment, 25 ° C./60, containing water and a glycol ether.
The weight loss rate at RH% is 30 minutes and the total amount of ink is 5 to 5.
25% and 24 hours, the remaining amount is 10% of the total ink amount
An ink composition for inkjet recording, which is 40%. 2. The ink composition of claim 2, wherein
Viscosities of 3 to 6 mPa.s and surface tension of 30 to
The inkjet ink composition according to claim 1, wherein the ink composition has a viscosity of 45 mN / m. 3. A change in viscosity of 1 mPa.s and a change in surface tension of 6 mN / m when the mixing ratio of water and glycol ether of the ink composition for ink jet is changed from 30: 1 to 6: 1. The ink composition for inkjet according to claim 1 or 2, wherein 4. The ink composition according to claim 1, wherein said glycol ether contains 1 to 10% by weight of ethylene glycol ether and / or propylene glycol ether. 5. The relative speed between a nozzle and a sheet is 10 ip.
5. The method for recording an ink composition for an ink jet according to claim 1, wherein a recording speed of at least s is used. 6. The method for recording an ink composition for an ink jet according to claim 5, wherein a piezoelectric element is used as a drive element of said on-demand type ink jet printer.