JP2000290555A - Hot melt type ink composition for ink jet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition excellent in flow stability, having a low viscosity and not suffering from separation by compounding a cyan ink composition, a yellow ink composition and a magenta ink composition each having a specific maximum saturation, a specific hue angle and a specific color difference. SOLUTION: A cyan ink composition containing a cyan pigment, a yellow ink composition containing a yellow pigment and a magenta ink composition containing a magenta pigment have a maximum saturation C* on a recording medium of at least 45, at least 70 and at least 60, respectively, a corresponding hue angle Ho of 240-270 deg., 90-110 deg. and 340-360 deg., respectively, and a color difference ΔE* when irradiated with a xenon light at a light quantity of 0.35 W/m2 at 340 nm for 100 hr, of not more than 3, not more than 5 and not more than 5, respectively. These ink compositions solid at room temperature are heated to melt and jetted onto a recording medium to form a recording dots thereby leaving a print. As a vehicle material is preferably employed an alcohol type wax having a hydroxyl value of 20-150, a melt viscosity of 5-50 mPa.s and a melting point of 50-1200 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-melt ink composition used for, for example, an ink jet recording apparatus.

[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, printing on paper where ink tends to soak causes "bleeding", and the recording medium is limited to processed paper. Overhead projector (OHP)
Even when recording on a sheet, special treatment is required on the sheet surface because the ink has poor drying properties. Therefore, as an ink composition that provides good print quality regardless of paper quality, using a hot melt ink composition made of a solid wax or the like at room temperature, liquefied by heating or the like, and adding some energy There has been proposed a hot-melt ink-jet recording system in which a recording dot is formed by jetting, cooling and solidifying while adhering to a recording medium to form recording dots.

As a major advantage of the ink jet system, the ink is solid at room temperature, so that it does not stain during handling, and the amount of evaporation of the ink during melting can be minimized, so that nozzle clogging does not occur. Further, since the ink is solidified immediately after the adhesion, there is no "bleeding", and various recording media such as Japanese paper, drawing paper, and postcards can be used without any pretreatment. U.S. Patents 4,390,369, 4,484,948, 5,350,78
No. 5,703,145 describes an ink composition that provides good print quality regardless of paper quality. In addition,
JP-A-5-311101 uses polyamide and fatty acid amide, JP-A-5-194897 and JP-A-6-107987 use glyceride, and describes a hot-melt ink composition for inkjet which has excellent light transmittance. Have been.

On the other hand, in order to improve the weather resistance of printed matter,
Generally, a pigment is used as a colorant for ink, and is used as ink for various printers such as a laser printer, a fusion transfer printer, a liquid inkjet printer, and a solid inkjet printer. For example,
Regarding the pigment ink used in the solid inkjet printer, JP-A-3-37278, 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-7-27
No. 8477, JP-A-7-306319, JP-A-7-316479
Many reports have been made, such as Japanese Patent Application Laid-Open No. 7-331141 and Japanese Patent Application Laid-Open No. 8-95836. JP-A-61-159470 describes a hot-melt ink comprising a vehicle containing an alcohol having 18 to 24 carbon atoms, and graphite previously dispersed in an oil carrier compatible therewith.

[0005]

However, the hot-melt ink composition generally has difficulty in maintaining compatibility between the components, and is in a molten state particularly when an organic pigment having excellent weather resistance is used as a coloring agent. It had a disadvantage that it was easily separated. As is well known, the sedimentation of the particles dispersed in the liquid changes depending on the particle size of the particles, the viscosity of the dispersion medium and the sedimentation time, and the higher the viscosity of the dispersion medium, the less the sedimentation. on the other hand,
When printing with an inkjet printer,
The lower the viscosity of the ink used, the higher the speed and the higher the density, which is advantageous for high-reliability printing.

As described above, the hot-melt ink-jet recording method using an organic pigment having excellent weather resistance as a coloring agent has many advantages as compared with the ink-jet recording method using a dye. ,
It is expected to be applied to not only facsimile machines but also posters for indoor and outdoor use, large signboards, car and elevator decorations, and prints on fabrics. However, as described above, there is a problem that ink separation and high-reliability printing quality cannot be achieved at the same time, and this has been a bottleneck in commercialization. Of the pigment colorants, those that are relatively easy to disperse in the vehicle resin often encounter trade-offs that are generally inferior in weather resistance.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink composition for a solid ink jet printer using a pigment which has sufficient flow stability, has a low viscosity and has no separation, and which is sufficient for ejecting ink droplets from fine nozzles. To provide things. A further important object of the present invention is to provide an ink composition for a solid ink jet printer that realizes high-saturation color printing.

[0008]

The gist of the present invention for solving the above-mentioned problems is to liquefy the ink composition at room temperature by heating and jet the ink composition onto a recording medium to form recording dots for printing. in inkjet hot-melt ink composition comprising a cyan pigment, the maximum chroma C * on the recording medium is 45 or more, the hue angle H ⁰ at this time 240-2
In the range of 70 ° and the light amount at 340 nm is 0.3
A cyan ink composition having a color difference ΔE * of 3 or less when irradiated with xenon light of 5 W / m ² for 100 h, a yellow pigment, and a maximum chroma C * on a recording medium of 70 or more;
A yellow ink composition having a hue angle H ^{0 in} the range of 90 to 110 ° and a color difference ΔE * of 5 or less when irradiated with xenon light having a light amount of 0.35 W / m ² at 340 nm for 100 h. objects and comprises a magenta pigment, the maximum chroma C * is 60 or more on the recording medium, the hue angle H ⁰ at this time 3
An object of the present invention is to combine a magenta ink composition having a color difference ΔE * of 5 or less when irradiated with xenon light having a light amount of 0.35 W / m ² at 340 nm in a range of 40 to 360 ° and 0.35 W / m ² for 100 hours.

Preferably, the cyan pigment is a pigment belonging to Pigment Blue 15: 4 in the color index, and the yellow pigment is a pigment selected from any of Pigment Yellows 93, 94, 95 and 128 in the color index. As the magenta pigment, a pigment belonging to Pigment Red 122 in the color index is preferably used.

[0010] More preferably, the ink composition contains an alcohol type wax having a hydroxyl value of 20 to 150.

The melt viscosity during printing is 15 mPa · s
It is good to be the following.

The above ink composition is desirably manufactured by kneading the pigment and wax at a rotational speed of 2,000 rpm or more with a bead mill holding the pigment and wax at a high temperature. The present invention having the above-described structure has a great feature in that a low melt viscosity during use, for example, 15 mPa · s or less can be ensured even at a high saturation and a high concentration.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The color characteristics used in the present invention are defined by the CIE: L *, a *, b * color system measured at a C light source and a viewing angle of 2 °. Similar other definitions, such as illuminant D _65, the measurement results based on the viewing angle 10 ° or the like corresponding to the value specified in the present invention should be converted numerical using absorption spectrum, chromaticity function like. Here, the saturation C *, the hue angle H ^0, and the color difference ΔE * are defined below, where H ⁰ is an angle unit and the others are dimensionless numbers.

[0014]

(Equation 1)

The xenon lamp used in the present invention and the amount of light used are conditions generally used in a weather resistance test.
It is not special. It is well known that a wavelength of 340 nm corresponds well to ultraviolet degradation of general organic materials.
A light amount of 0.35 W / m ² is a standard condition corresponding to sunlight. It has been reported that under these conditions, the acceleration is about 5 to 10 times that of direct sunlight. Details on this are available in many publications, e.g. E. FIG. Materials by Crudeson, Material Life Society of Japan (1992), LSCrump
Written by ATLAS Sun Spots, 3rd / 4th Quarter, p1-6 (1996),
Model Selection Guide (1989) (Toyo Seiki), Xenotest Materials (1986) (Heraerus), Nakano et al., Convertech,
p56-59 (1998.4).

According to the present invention, when printing is performed under the condition that gives maximum saturation of each of cyan, yellow and magenta colors,
The value of the maximum saturation C * and for this the hue angle H ⁰ is limited to a specific range, further limited to a specific range resulting color difference △ E * light resistance test for print of this condition. That is, for cyan, the maximum saturation C * 45
As described above, the hue angle H0 is 240 to 270 ° and ΔE * 3 or less. For the yellow color, the maximum saturation C * 70 or more,
Hue angle H ⁰ is 90~110 °, △ E * 5 or less, for the magenta color, the maximum chroma C * 60 or more, a hue angle H0
Is 340 to 360 ° and ΔE * 5 or less.

It is well known in the art to limit the saturation and hue angle to specific ranges when performing high-quality printing. Printing has not been done in the past. It is well known that the saturation of a print varies depending on printing conditions, such as the ink amount of each dot, the color material density in the ink, and the number of dots. Is defined as the maximum value that can be realized by the ink at the maximum value when the value changes in the entire possible range. It is well known that the saturation increases as the ink amount and the colorant density increase, reaches a specific maximum value, and then decreases (darkens) again. The optimal color material amount is defined as a value under the selected condition.

A feature of the present invention resides in that a combination of these colors is used. In the present invention, it is intended to realize full-color printing by a so-called four-color system, and it is particularly preferable to limit each color to the range of saturation and hue angle shown in the present invention in order to achieve a wide color reproduction range. .

In the present invention, a blue or cyan pigment is used. These include, for example, pigments indicated by the following color index. For example, Pigment Blue 1, 15,
15: 1, 15: 2, 15: 3, 15: 4, 15: 5,
15: 6, 16, 17: 1, 22, 27, 28, 29,
36, 60, and the like.

The most suitable pigment for solving the problem of the present invention is
Pigments, commonly referred to as phthalocyanine blue, are well known materials for many good properties. For phthalocyanine blue (such as copper phthalocyanine), α, β, γ, δ,
Numerous crystal forms such as ε, π, ρ, τ, X, and R types have been reported, and these are shown in color index as Pigment Blue 15 (α type), 15: 1 (monochloro substituted), 15: 2 (Monochloro substituted amorphous form), 15:
3 (β type), 15: 4 (β type non-crystalline type, non-aggregated type), 1
5: 5 (γ type), 15: 6 (ε type) and the like. Metal-free phthalocyanine (Pigment Blue 16),
Polyhalogen-substituted copper phthalocyanines (Pigment Green 7, 36) are also related pigments.

In the present invention, in particular, cyan pigments belonging to pigment blue 15: 4 in color index are most effectively used. This pigment has the best level of light resistance (ultraviolet discoloration resistance), and exhibits an ideal cyan hue as a coloring material. Pigments belonging to this color index include, for example, the following elemental pigments and treated pigments, but the present invention is not particularly limited thereto.

Chromofine Blue 4930P, 4940, 4942, 495
0, 4966, 4973, 4976EP, 4983, S-2100, S-32, cyanine blue 4933GN-EP, 4940, 4973, 4796-EP, 127-EPS, 4
927G-EPB (all manufactured by Dainichi Seika), Fastogen Blue 5410G, 5
412G, 5415, 5480, 5481, 5485, 5486, 5488, FGS, GNP
S, GNPM-K, GNPW, NK, TGR-F, 5421, 5422, 5424, 542
5, 3F-12, GFA, GFB, NK-G, 5412SD (Dai Nippon Ink), Heliogen Blue D7060T, D7105T, 7160TD, L7101
F, D7106, D7111 (all made by BASF), HostapermBlue B
FL, Monarch Blue GFR X-3374 (Hoechist), Irgalit
e Blue 4GF-BR, BGO, GLNF, GLVO, GNFO, RLO (Cib
a Geigy), Lionol Blue 700-10FG, 7481-G, FG-7397
-G, FG-7400-G, GF-41703, FG-7405-G, FG-7408, 7850G
(Made by Toyo Ink), Monastral Blue FGX (ICI
), Sunfast Blue 15: 4, Spectra PACC Blue 15: 4
(Manufactured by SunChemical), Colortex Blue 510, Sanyo Cyanin
e Blue 3008, J620, KRG (manufactured by Sanyo Dye), Isol Phthalo
Blue GB2P 372, Predichip Blue GB 1660, Predisol B
lue GBP-C 585, GFH-CAB 2660, GP-C 9559 (KemiskVaer
k). In the present invention, a yellow (yellow) pigment is used. These include, for example, pigments indicated by the following color index. Pigment Yellow 1, 3, 1
2, 13, 14, 17, 34, 35, 37, 55, 7
4, 81, 83, 93, 94, 95, 97, 108, 1
09, 110, 128, 137, 138, 139, 15
1,153,154,155,157,166,16
7, 168, 180, 185, 193, Pigment Orange 13, 16, 20, 36 and the like.

The most suitable pigments in the present invention are those belonging to Pigment Yellows 93, 94, 95 and 128. Both are disazo organic pigments developed by Ciba Geigy and are well known materials for their many good properties. Among the yellow (yellow) color pigments, it has the best level of light resistance (ultraviolet discoloration resistance),
Furthermore, benzidine chloride, which is a problem in occupational safety and health during production, is not used. The pigments belonging to the above color index include, for example, elementary pigments and treated pigments described below, but the present invention is not particularly limited thereto.

Pigment Yellow 93 includes Cromop
htal Yellow 3G F, 3G-MC, 3GP, 3G, Filofin Yellow 3
G, Micronyl Yellow 3G-AG, 3G-AQ, 3G-K, 4G-A, Versa
l Yellow 3G, Yellow EMD-387, PEC-387, Microlith Ye
llow 3G-WA (above Ciba Geigy), Pigment Yellow 9
3. Colortex Yellow UG379 (above manufactured by Sanyo Dye) and Pigment Yellow 94 include Cromophtal Yellow 6G (Ci
ba Geigy), Crom as Pigment Yellow 95
ophtal Yellow GR-P, GR, Micronyl Yellow GR-AG, GR-
AQ (above Ciba Geigy), Versal Yellow GR (Ostacolo
r), Yellow EMD-388, PEC-388, VC-388 (all manufactured by Sumitomo Chemical), and Pigment Yellow 128 as Cromopht
al Yellow 8GN, 8G, Micronyl Yellow 8GN-AG, 8GN-AQ
(Made by CibaGeigy).

Further, magenta and red pigments are used in the present invention. These include, for example, pigments indicated by the following color index. Pigment 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, 104, 108, 112, 122, 123, 14
4, 146, 149, 166, 168, 169, 17
0, 177, 178, 179, 184, 185, 20
8, 216, 226, 238, 257, pigment violet 3, 19, 23, 29, 30, 37, 50,
88, Pigment Orange 13, 16, 20, 36 and the like. Of these, the most preferred pigments for the present invention are pigments commonly referred to as quinacridone magenta belonging to Pigment Red 122, which are well known materials for many good properties. For example, it has the best level of light fastness (ultraviolet light fading resistance) among pigments, and exhibits an ideal magenta hue as a coloring material. Pigments belonging to this color index include, for example, the following elemental pigments and treated pigments, but the present invention is not particularly limited thereto.

Chromo Fine Magenta 6878, 6880, 688
6, 6887 (all made by Dainichi Seika), Colortex Red UG276, UG5
15, FSL-M (manufactured by Sanyo Dye), Liogen Magenta RR-122
(Toyo Ink), Toner Magenta E02, Hostaperm Pin
k E, EB, E02, PV Fast PinkE01, E02 (Hoechist
Manufactured), KET Red310, 309, 346, Fastogen Super Magenta
RG, RTS, R, RE-01, RE-02, RE-03, RE-03T, RTS-D, R
TS-D2 (Made by Dainippon Ink), M-122 (Morishita Sangyo),
Monaprin Rubine 3BE, 3B, Monolite Red 3BE-HD, Mono
lite Rubine 3B, Polymon Red 6BED, Vynamon Red 6B-F
W (above ICI), Sunfast Magenta 122, Quinacrido
ne Magenta 22 (above Sun Chemical), Red EPCF-11
7, HPA-117, PEC-117 (Sumitomo Chemical), Sandorin Br
illiant Red 6BLN, Sandrin Magenta BLTE (Claria
nt), Aqua Plus Magenta Paste WR-9525, Quindo Mag
enta Presscake RV-6827, 6831, Quindo Magenta RV-68
03, 6823, 6828, 6832 (all made by Miles) and others.

In addition to directly using the elementary pigment, a masterbatch in which the pigment is dispersed in a suitable resin in advance, for example, carnauba wax, acrylic resin, polyethylene, a part of an ink vehicle, or the like is produced and used. It is also possible.

The vehicle material is not particularly limited as the hot melt ink composition of the present invention, and may be a monoamide, bisamide, tetraamide, polyamide, ester amide, polyester, polyvinyl acetate, acrylic or methacrylic polymer, or styrene. It can be composed of one or more components selected from molecules, ethylene vinyl acetate copolymers, polyketones, silicone resins, coumarone resins, fatty acid esters, triglycerides, natural resins, natural and synthetic waxes, and the like. However, the color developability (color density per addition density) of each pigment particularly used in the present invention
Is not necessarily high, and it is difficult to produce a homogeneous fine particle dispersion, and if the concentration is high, there is a phenomenon that the melt viscosity is excessively increased, and it has been difficult to practically use the solid ink as a solid ink.

In order to solve the above-mentioned problem, in the present invention, among the above-mentioned vehicle materials, particularly, an alcohol type wax material is suitably used. It has been found that this material is extremely exceptionally compatible with organic pigments, especially the pigments of the present invention, and makes it possible to relatively easily produce a dispersion in which the aggregate state has been dissociated. The reason for this is not clear, but may be based on some interaction between hydroxyl groups and functional groups in the pigment molecule. In accordance therewith, it is possible to achieve such a characteristic that a high density at which sufficient saturation can be obtained and a melt viscosity at the time of use becomes low viscosity suitable for ink jet recording.

Particularly preferably used as the alcohol type wax is a homopolymer of alcohol and ethene, or a wax produced by an oxidation reaction using paraffin wax, microcrystalline wax or petrolatum as a raw material. The polymer contains an alcohol having 24 to 55 carbon atoms. The alcohol type wax of the present invention is a linear, fully saturated type, and has a higher reactivity than alcohols obtained by a conventional fractionation method, such as a position where hydroxyl groups are uniformly attached to all carbons. Things are desirable.

Specifically, UNILIN350, UNILIN425, UNIL
IN550, UNILIN700, and Unitox 420, Unitox 450, Unitox 48 obtained by ethoxylation of these
0, Unitox 520, Unitox 550, Unitox 7
20, Unitox 750 (made by Toyo Petrolite) or the like can be used. Furthermore, OX1949, OX020T, NPS9210, NPS9125, and NPS9035 are alcohol-rich alcohol-type waxes produced by oxidation reaction using paraffin wax, microcrystalline wax, and petrolatum as raw materials.
(Made by Nippon Seiwa) is desirable. Also, KOW, VLTN-4, VLT
N-5 and VLTN-6 (manufactured by Kawaken Fine Chemical) are also included. Particularly preferred are UNILIN425, UNILIN550, OX1949
It is.

The hydroxyl value of these alcohol waxes is preferably from 20 to 150, and most preferably from about 60 to 130. Hydroxyl value of 2
If it is less than 0, the above-mentioned pigment is insufficiently dispersed and precipitates easily occur, and if it exceeds 150, excessive polarizability causes separation of the pigment and the vehicle. Here, the hydroxyl value (hydroxyl value) is based on the measurement method defined in ASTM E222. As a standard of the hydroxyl value relative to the molecular weight, an alcohol type wax having a value of hydroxyl value / (57 × molecular weight) of 1 or less, preferably 1 to 0.5 is suitable.

The melt viscosity of the alcohol wax is preferably 5 to 50 mPa · s, more preferably 5 to 30 mPa · s. 5mP
If the viscosity is less than a · s, sedimentation of the pigment cannot be prevented, and 50 mPa · s
If the viscosity exceeds, it is difficult to perform ink jet recording. Mainly in connection with the above-mentioned viscosity requirements, the preferred alcohol type wax has a carbon number of about 18 to 100, and particularly preferably 25 to 55. A wax having a carbon number of less than 25 has too low a viscosity so that the dispersion stability of the pigment becomes insufficient. For the same reason, the molecular weight is about 200 to 1500, preferably 30
A range from 0 to 700 is desirable.

The melting point of the alcohol type wax is preferably from 50 to 120 ° C. from the viewpoints of ink jetting stability and storage stability of printed matter. Particularly desirable is 70 ° C. or more and 100 ° C. or less. Since stability to heat and light is required, the acid value is particularly preferably 12.0 or less and the iodine value is preferably 3 or less, and these can provide sufficient storage stability of printed matter as a main component of the ink for inkjet.

The above-mentioned alcohol-type waxes have good compatibility with plant waxes represented by candelilla wax, carnauba wax, castor wax and wood wax, and can be used in combination. In addition, for example, petroleum waxes such as paraffin wax and microcrystalline wax, polyethylene wax, higher saturated and unsaturated fatty acids such as stearic acid and behenic acid, ketones such as stearone and laurone, fatty acid ester amides, saturated or unsaturated fatty acid amides , Fatty acid esters, castor oil, saturated and unsaturated fatty acid glycerides including castor oil and the like, as well as rosin resins, hydrocarbon resins, amide resins, polyester, polyvinyl acetate, acrylic acid and methacrylic acid polymers, The characteristics can also be improved by adding a high molecular weight resin such as a styrene-based polymer, an ethylene-vinyl acetate copolymer, polyketone, silicone, or coumarone. The vehicle system used in the present invention can be widely applied to other pigments.

As other inks to be combined with the present invention or as a colorant to assist, many pigments which are well dispersed in the vehicle of the present invention and have excellent heat stability can be used. A soluble dye (Solvent Dye) can also be used in combination as a coloring agent. Any colorant, such as an oil dye, can be used as long as it is compatible with the other ink components. Two or more types of colorants can be mixed and used as needed for color adjustment. Various surface treating agents, surfactants, viscosity reducing agents, antioxidants, antioxidants, antioxidants, crosslinking accelerators, ultraviolet absorbers, plasticizers, preservatives for further developing functionality in the ink composition of the present invention. , A dispersant, a dye and the like can be mixed.

The amount of the pigment added is 0.5 to 5 times the total amount of the ink.
%, Especially 0.7% by weight or more is a suitable amount. Especially desirable
More preferably, it is 0.7 to 2% by weight. If it is less than 0.5% by weight
Insufficient chroma, more than 5% by weight may cause ink viscosity characteristics
This has an adverse effect and reduces the saturation. Addition amount is color
It is well known that it has a significant effect on hue,
H ⁰, The maximum chroma C * must be appropriately selected.
Further, based on the specific interaction between the vehicle and the pigment,
Different color tone occurs even with the same amount of one pigment
Sometimes. Further, the color tone varies depending on the particle size. The present invention
Considering these effects, the optimal mixing amount of
Determined based on degree, hue and lightfastness.

Various known pulverizing or dispersing apparatuses can be used for mixing and dispersing the above-mentioned vehicle, colorant and other components. These include high-speed rotating mills, roller mills,
There are categories such as a container drive medium mill, a medium stirring mill, a jet mill, and the like. Century Mill, Pressure Mill, Agitator Mill, Two Roll Extruder, Two Roll Mill, Three Roll Mill, Nitchie Mill, Kneader, Mixer, Colloid Mill, Stone Mill, Cadie Mill, Planetary Mill, Ball Mill, Paddle Mixer, Attritor, Flow Jet Mixer, Slasher Mill, peg mill, microfludizer, CLEARMIX, rhino mill, homogenizer, bead mill with pin,
There is a horizontal bead mill and the like.

The kneading time is variously set by the apparatus.
For kneading, a method in which well-known components are melt-kneaded all at once, a method in which a coloring agent is previously mixed at a high concentration and diluted into a master batch, a method in which components are sequentially added and mixed, and a method in which a component is dispersed in a liquid and dispersed in a solid phase Various methods used for paint, ink, resin coloring, etc., such as a flash method to be introduced, can be used.

In the present invention, a high-speed rotating bead mill is used. The number of revolutions is a particularly important factor, and even in the same method, if the number of revolutions is low, the pulverization efficiency is inferior. 1,000 rpm
The above is appropriate. Particularly preferably, 2,000 to 4.0
It is in the range of 00 rpm. If it is less than 1,000 rpm, pulverization and dispersion are insufficient, and excessive production time is required. If it exceeds 4,000 rpm, excessive equipment is required to maintain high-speed rotation at high temperatures, which is not practical. The material of the bead is not particularly limited, but zircon, zirconia, steel or the like is used. If the bead diameter is too large, the crushing efficiency is high, but the particle size cannot be sufficiently reduced. If the bead diameter is too small, it takes a long time for kneading, so an appropriate range is selected. 0.5 to 5 mmφ is suitable, and particularly preferably 0.5 to 2 mmφ. In the case of phthalocyanine pigments, crystal dislocation is likely to occur during kneading due to heat, mechanical impact, and interaction with a specific organic substance, and the color tone, dispersibility, and the like are likely to change significantly. In the production of the ink of the present invention, it is necessary to optimize the hue and saturation in consideration of these conditions.

The preparation of high quality inkjet inks requires a balance of many important factors. The ink of the present invention satisfies several well-known requirements for application to hot melt inkjet printers. That is, the ink has sufficient hardness and stability at room temperature, and has high reliability in storage before printing and image quality after printing. After attaching to a recording medium, it has sufficient transparency and saturation, and forms a uniform thin film to give a printed matter of good image quality. While these requirements are complex and cannot always be clearly quantified for the inks of the present invention, for example, hot melt inks with relatively low melting points are typically susceptible to bleed and offset. Even when stored at 40 ° C., it is necessary that offset does not occur in a state where printed matters are stacked. However, the higher the melting point of the ink, the higher the viscosity,
The melt viscosity at the time of printing is 50 mPa · s or less, especially 5 to 1
A range of 5 mPa · s is desirable on the apparatus. Excessive viscosities require more energy at the time of injection, and materials with too low viscosities cause problems in storage stability at room temperature. The viscosity at room temperature (25 ° C.) is 10,000 mPa · s or more.

The bending property of the printed matter was 5 in a mandrel test using a transparency film.
It is desirable to pass a test of not more than mmφ, especially not more than 3 mmφ.

For many inks, the viscosity can be reduced to a range suitable for ejection by increasing the ejection temperature.
Increasing the ejection temperature causes thermal stability problems, and heating for a long time in an ink reservoir (ink chamber) or print head may decompose the ink or corrode a metal material in contact with the ink. Therefore, the temperature at which the ink is melted at the time of printing is set at 100 to 100 to make the apparatus simple and low-cost.
The range of 150 ° C. is optimal. Surface tension during melting is 30
mN / m or less is desirable. It is desirable that the volume change upon transition from the molten state to the solid be 10% or less.

Further, the composition can be used in a conventionally known ink jet printer such as an office printer, a printer used for industrial marking, a wide format type printer, which ejects ink droplets only when printing is necessary. It can be used for plate and plate making printers, label printers and all types of printers having this typical operation.

Examples of the recording medium include paper, plastic films, capsules, gels, metal foils, cloths, and the like. However, as long as non-contact printing is possible, a wide variety of media can be used. Not something. A method of once recording on a transfer body and transferring it to a recording medium, and a recording method including a process such as a pressurizing and heating device can also be used.

Next, the present invention will be described in detail with reference to examples, but is not limited to the described examples. Example 1 As a vehicle, a yellow pigment belonging to Color Index Pigment Yellow 93 was used as a coloring agent, in which a small amount of a dispersant was added to an alcohol type wax (manufactured by Toyo Petrolite, trade name: UNILIN425). (Manufactured by Hitachi Koki: HG3) was added at a concentration of 1.5% by weight based on the vehicle amount.
Heating and kneading at 130 rpm at 10,000 rpm until a homogeneous molten mixture is obtained according to 0), followed by filtration under heating and pressure to remove impurities and the like. A hot melt ink of color was obtained.

Further, a magenta pigment belonging to Color Index Pigment Red 122 (trade name: KET Red 310, manufactured by Dai Nippon Ink) was added to the above vehicle as a coloring agent at a concentration of 2.5% by weight based on the total amount, and a bead mill (manufactured by Eiger) was added. : Motor mill M-250, beads: zircon 1φ) at 130 ° C. until a homogeneous molten mixture is obtained at 2,50 ° C.
The mixture was heated and kneaded at a rotation speed of 0 rpm, followed by filtration under heating and pressure to remove impurities and the like, and was allowed to cool at room temperature to obtain a homogeneous magenta hot melt ink.

Further, the above-mentioned UNILIN425 was used as a vehicle for 5 hours.
5% by weight and 45% by weight of another alcohol type wax (manufactured by Nippon Seisaku: OX1949), and as a coloring agent, a cyan pigment belonging to Color Index Pigment Blue 15: 4 (manufactured by Dainippon Ink. Name: Fastogen
Blue 5410G) was added in a concentration of 1.5% by weight based on the total amount, and the mixture was similarly heated and kneaded with a bead mill, filtered under heating and pressure, and allowed to cool at room temperature to obtain a homogeneous cyan hot melt ink. .

The melt viscosity of these raw inks was 130
At 0 ° C., yellow (hereinafter referred to as Y), magenta (hereinafter referred to as M), and cyan (hereinafter referred to as C) in the order of 11.
The values were 3 mPa · s, 12.0 mPa · s and 11.4 mPa · s.

[0050] Further, the respective ink jet printer (Hitachi Koki Ltd.: JOLT SJO1A) to perform printing put was measured chroma C * and hue H ⁰ with the color difference meter (Nippon Denshoku Ltd. Σ90). The paper used was Xerox 4025
It is plain paper. Table 1 shows the results.

[0051]

[Table 1]

In Table 1, Y, M, and C represent the printing results of the yellow, magenta, and cyan inks, respectively, and R, G, and B represent the printing results of the red, green, and blue colors obtained by equally mixing each single color. Was. These are represented by CIE chromaticity gamut diagrams (a *,
b * plot) is shown in FIG. In FIG. 1, each point indicates a measured value of each color (corresponding to Table 1).

In the figure, the curve shown by the thick line is the measurement result of the color change obtained when the printing density is changed for each single color ink. It can be seen that high saturation can be obtained in a limited hue range (that is, a density range). Many other curves in the figure are based on the color characteristics of a single color.
Chromaticity is calculated and plotted when single colors are mixed at various ratios based on the lka-Munk (Kuberka-Munk) equation. Except for G, the chromaticity of each of R and B is calculated close to a value obtained experimentally. The envelopes of these curves show the color reproduction range obtained with these Y, M, and C inks, and it can be seen that a good wide range can be obtained with the ink system of the present invention.

For the prints of the six colors (Y, M, C, R, B, and G), an accelerated light degradation test was performed by irradiation with a xenon lamp. A xenon lamp test apparatus (atlas: SunChe) whose light intensity at 340 nm is controlled to 0.35 W / m ^2.
In x), continuous irradiation was performed at a sample temperature of 60 ° C., and the color change ΔE of the sample was measured as appropriate. The results are shown in FIG.

In FIG. 2, ΔE for irradiation for 100 hours was 3.0 or less, and extremely good light resistance was maintained at 5.0 or less even after 500 hours.

The ink of the present invention described above was able to achieve both good color reproduction range and light fastness. Examples 2 to 5 The inks of the present invention having various compositions shown in FIG. 3 were prepared and evaluated for melt viscosity, color characteristics and light fastness. The numbers in the vehicle part in FIG. 3 indicate the weight% of each component at the time of mixing, and the coloring material is the weight% with respect to the vehicle 100.
FIG. 3 also shows the results of Example 1 for comparison.

For kneading, the same homogenizer as in Example 1 was used.
Alternatively, using a bead mill, the printing method and the characteristic measuring method are the same as those in the first embodiment. Each of the three color combinations showed good maximum saturation and a hue angle and light fastness in a sufficient range for matching the three colors, indicating that the ink combination of the present invention was extremely effective.

[0058]

The hot-melt ink composition for ink-jet printing of the present invention achieves both wide-range color reproduction and high light fastness, so that it has been impossible to produce a robust color print which can be stored for a long period of time. This makes it possible to apply it to a wide range of applications that were previously difficult, such as creating printed matter to be displayed outdoors.

[Brief description of the drawings]

FIG. 1 is a CIE chromaticity gamut diagram of each color ink.

FIG. 2 is a graph showing the results of accelerated light degradation tests for each color ink.

FIG. 3 is a table showing ink compositions of respective examples.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C056 EA13 FC01 4J039 AB12 AD01 BC41 BC60 BE01 CA09 DA05 EA15 EA16 EA17 EA35 EA42 EA44 GA24

Claims (5)

[Claims] An ink-jet hot-melt ink composition for liquefying a solid ink composition at room temperature by heating and jetting it onto a recording medium to form recording dots and perform printing, comprising a cyan pigment, The maximum saturation C * on the recording medium is 45
Above, the hue angle H ⁰ at this time is in the range of 240 to 270 °, and the color difference when the amount of light at 340nm was 100h irradiated with xenon light of 0.35W / m ² △ E * is 3 or less cyan an ink composition comprising a yellow pigment, the recording medium on the maximum chroma C * is 70 or more, the hue angle H ⁰ at this time is in the range of 90 to 110 °, and the amount of light at 340 nm 0.35 W / M ² xenon light irradiation for 100 h, contains a yellow ink composition having a color difference ΔE * of 5 or less, a magenta pigment, a maximum chroma C * on a recording medium of 60 or more, and a hue at this time. Angle H ⁰ is 340-360 °
And the light amount at 340 nm is 0.35 W /
A hot-melt ink composition for color inkjet, comprising a magenta ink composition having a color difference ΔE * of 5 or less when irradiated with m ² xenon light for 100 hours. 2. The cyan pigment is a pigment belonging to Pigment Blue 15: 4 in the color index, and the yellow pigment is any one of pigment yellows 93, 94, 95 and 128 in the color index. The hot-melt ink composition for inkjet according to claim 1, wherein the pigment is a pigment belonging to Pigment Red 122 in a color index. 3. The ink-jet hot-melt ink composition according to claim 1, wherein the ink composition contains an alcohol-type wax having a hydroxyl value of 20 or more and 150 or less. Melt type ink composition. 4. The hot-melt ink composition for ink-jet recording according to claim 1, wherein the melt viscosity during printing is 15 mPa · s or less. 5. The hot melt for an ink jet according to claim 1, wherein the pigment and the wax are produced by kneading at a rotation speed of 2,000 rpm or more by a bead mill maintained at a high temperature. Mold ink composition.