JP2000007968A - Hot-melt ink composition for ink jet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hot-melt ink composition having a low viscosity, not undergoing separation, and exhibiting improved flow stability when it in the form of ink drops is jetted from fine nozzles, which composition gives a print specified in the maximum saturation, a hue angle, and a color difference on a recording medium. SOLUTION: A cyan pigment belonging to Pigment Blue 15:4 in an amount of 0.5-5 wt.%, desirably, 0.7-2 wt.%, an alcohol type wax having a hydroxyl value of 20-150, and optionally, a surface-treating agent, a surfactant, a viscosity lowering agent, an antioxidant, an antideteriorant, a crosslinking accelerator, an ultraviolet absorber, a plasticizer, an antiseptic, a dispersant, a dye, or the like, are fed into a bead mill kept at a high temperature and kneaded at a revolution speed of 1,00 rpm or above, desirably, 2,000-4,000 rpm to obtain a room-temperature-solid hot-melt ink composition for ink jet which can give on a recording substrate a print having a maximum saturation (chromaticity) C* of 45 or above, a hue angle H0 of -120 to 90 deg.C and a color difference ΔE* of 3 or below after irradiation with xenon light at a light quantity of 0.35 W/m2 at a wavelength of 340 nm for 100 hr.

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
9, 5,703,145 describe ink compositions that provide good print quality regardless of paper quality. In addition, JP-A-5
JP-A-311101 describes polyamide and fatty acid amides, and JP-A-5-194897 and JP-A-6-107987 describe a hot-melt ink composition for inkjet using glyceride and having excellent light transmittance. ing.

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 are 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 for a solid ink jet printer using a pigment which has sufficient flow stability, low viscosity and no separation, which is sufficient to eject ink droplets from fine nozzles. It is to provide a composition. It is a further important object of the present invention to provide an ink composition for a solid ink jet printer which realizes a high chroma cyan color.

[0008]

The gist of the present invention to solve the above-mentioned problems is to provide a hot-melt type ink-jet printing method in which a solid ink composition is liquefied by heating at room temperature and ejected to form recording dots on a recording medium. In the ink composition, the maximum chroma C * of the ink composition on a recording medium is 4
5 or more, the hue angle H0 at this time is in the range of -120 to -90 °, and the light amount at a wavelength of 340 nm is 0.35 W
/ M ² xenon light irradiation for 100 h
Is 3 or less.

Preferably, the ink composition comprises Pigment Blue 1 in a color index as a coloring material.
A pigment belonging to 5: 4 or having a hydroxyl number of 20
It is preferable to contain at least 150 or less alcohol type wax.

[0010] More preferably, the melt viscosity at the time of printing is 15 or less.
It is good to be below mPa · s.

The ink composition is manufactured by kneading a pigment and a wax at a rotational speed of 2,000 rpm or more by a bead mill holding the pigment at a high temperature.

The color characteristics used in the present invention are defined by the CIE: L *, a *, b * color system measured with a C light source and a viewing angle of 2 °. Other similar definitions, eg D65 light source, viewing angle 10 °
In order for the measurement result based on the above to correspond to the value specified in the present invention, numerical conversion using an absorption spectrum, a chromaticity function, or the like is necessary. Here, the saturation C *, the hue angle H0, and the color difference ΔE * are defined as follows, where H0 is an angle unit (defined in a counterclockwise direction), and the others are dimensionless numbers.

[0013]

(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. This condition is 5 to 10 for direct sunlight.
It has been reported that the irradiation dose is about twice as large. Details on this are available in many publications, e.g.
E. FIG. Materials by the Society for Materials Life by Crudeson (199
2), L. S. ATLAS Sun Spots by Crump, 3rd / 4th Quart
er, p1-6 (1996), Model selection guide (1989) (Toyo Seiki), Xenotest material (1986) (Heraerus), Nakano et al.,
Convertech Magazine, p56-59 (1998.4).

In the ink composition of the present invention, the maximum chroma C * 45 or more on the recording medium, and the hue angle H0-12 at this time.
The range of 0 to -90 ° and the color difference ΔE * 3 or less limits the practically sufficient range of color characteristics and light fastness in the region obtained with the cyan ink of the present invention. It is well known that the saturation of an ink composition on a recording medium varies depending on the amount of ink, color material density, and printing conditions. It is defined as the maximum saturation that can be realized by the ink at the maximum value when the ink changes in the range. When the ink amount and the color material density are increased, the saturation increases, reaches a specific maximum value, and then decreases again (darkening).

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, 2
8, 29, 36, 60, and the like.

The pigments most suitable for solving the problem of the present invention are pigments usually referred to as phthalocyanine blue, which are well known materials for their many good properties. FIG. 1 shows the molecular structure. Phthalocyanine blue (copper phthalocyanine, etc.)
Has reported many crystal types such as α, β, γ, δ, ε, π, ρ, τ, X, and R types, and these are represented by a color index of Pigment Blue 15 (α type), 1
5: 1 (monochloro substituted product), 15: 2 (monochloro substituted product amorphous type), 15: 3 (β type), 15: 4 (β type amorphous type, non-aggregated type), 15: 5 (γ type) ), 15: 6 (ε
Type). Metal-free phthalocyanine (Pigment Blue 16) and polyhalogen-substituted copper phthalocyanine (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. Examples of pigments belonging to this color index include elementary pigments and treated pigments described below,
The present invention is not particularly limited to these.

Chromofine Blue 4930P, 4940, 4942, 495
0, 4966, 4973, 4976EP, 4983, S-2100, S-32, cyanine blue 4933GN-EP, 4940, 4973, 4976-EP, 127-E
PS, 4927G-EPB (all manufactured by Dainichi Seika), Fastogen Blue 5410G,
5412G, 5415, 5480, 5481, 5485, 5486, 5488, FGS, GN
PS, GNPM-K, GNPW, NK, TGR-F, 5421, 5422, 5424, 5
425, 3F-12, GFA, GFB, NK-G, 5412SD (all manufactured by Dainippon Ink), Heliogen Blue D7060T, D7105T, 7160TD, L7
101F, D7106, D7111 (all made by BASF), Hostaperm Bl
ue BFL, Monarch Blue GFR X-3374 (Hoechist), Ir
galite Blue 4GF-BR, BGO, GLNF, GLVO, GNFO, RLO
(Manufactured by Ciba Geigy), Lionol Blue 700-10FG, 7481
−G, FG−7397−G, FG−7400−G, GF−41703, FG−7405
-G, FG-7408, 7850G (Toyo Ink), Monastra
l Blue FGX (made by ICI), Sunfast Blue 15: 4, Spectra
PAC C Blue 15: 4 (SunChemical), Colortex Blue
510, Sanyo Cyanine Blue 3008, J620, KRG (manufactured by Sanyo Dyestuff), Isol Phthalo Blue GB2P 372, Predichip Blue G
B 1660, Predisol Blue GBP-C 585, GFH-CAB 2660, G
PC-9559 (manufactured by Kemisk Vaerk). In addition to directly using the raw pigments, the pigments may be preliminarily converted to a suitable resin, for example, carnauba wax, acrylic resin, polyethylene,
It is also possible to produce a masterbatch dispersed in a part of the ink vehicle or the like and use it.

The vehicle material is not particularly limited as the hot melt ink composition of the present invention, and includes a monoamide, a bisamide, a tetraamide, a polyamide, an ester amide, a polyester, a polyvinyl acetate, an acrylic acid-based and a methacrylic acid-based polymer, and a styrene-based polymer. 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 added concentration) of the cyan pigment particularly used in the present invention is not always high, and in addition, it is difficult to produce a uniform fine particle dispersion. If the concentration is high, the melt viscosity increases excessively. Due to the phenomenon, it has been conventionally difficult to put the solid ink into practical use.

In the present invention, among the above vehicle materials, alcohol type wax materials are particularly preferably 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.

The alcohol type wax is more preferably a homopolymer of alcohol and ethene, or a wax produced by an oxidation reaction using paraffin wax, microcrystalline wax, petrolatum as a raw material. Contains alcohol of number 24 or more and 55 or less.

The alcohol type wax of the present invention includes:
Desirably, it is a linear, fully-saturated type and more reactive than alcohols obtained by conventional fractionation methods, such as the position of the hydroxyl group is uniformly attached to all carbons.

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. In addition, paraffin wax, microcrystalline wax, OX1949, OX020T, NPS9210, NPS9125, NPS9035 as alcohol-rich alcohol type wax produced by oxidation reaction using petrolatum as a raw material
(Made by Nippon Seiwa) is desirable. Also, KOW, VLTN-4, VL
TN-5 and VLTN-6 (manufactured by Kawaken Fine Chemical) are also included. Particularly preferred are UNILIN425, UNILIN550, OX19
49.

The hydroxyl value in the ink composition of the present invention 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 AS
It is based on the measurement method defined in TM E222 Rev.
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 during printing of the ink composition of the present invention is 5 to 50 mPa · s, preferably 5 to 30 mPa · s. If the viscosity is less than 5 mPa · s, sedimentation of the pigment cannot be prevented, and if the viscosity exceeds 50 mPa · s, it is difficult to perform ink jet recording.

Mainly in connection with this viscosity requirement, the preferred alcohol number wax has a carbon number of about 18 to 100, 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 is insufficient, and a wax having a carbon number of more than 100 has an excessively high viscosity and makes inkjet recording difficult. 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 ink composition of the present invention is desirably from 50 to 120 ° C. from the viewpoint of the ejection stability of the ink and the storage stability of the printed matter. Particularly desirable is 70 ° C. or more and 100 ° C. or less.

Since heat and light stability are required, it is particularly desirable that the acid value is 12.0 or less and the iodine value is 3 or less. These can provide sufficient storage stability of printed matter as a main component of the ink for ink jet. .

These compounds have good compatibility with plant waxes such as candelilla wax, carnauba wax, castor wax and wood wax, and can be used as a mixture. 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 a colorant for assisting the ink of another color or a cyan color to be combined with the present invention, many pigments which are well dispersed in the vehicle of the present invention and have excellent heat stability can be used. Although not particularly limited, for example, the following organic or inorganic pigments described in the color index can be used. That is, magenta and red (red) pigments are used.

These include, for example, pigments represented by the following color index.

Pigment Red 3, 5, 19, 22,
31, 38, 43, 48: 1, 48: 2, 48: 3, 4
8: 4, 48: 5, 49: 1, 53: 1, 57: 1, 5
7: 2, 58: 4, 63: 1, 81, 81: 1, 81:
2, 81: 3, 81: 4, 88, 104, 108, 11
2, 122, 123, 144, 146, 149, 16
6, 168, 169, 170, 177, 178, 17
9, 184, 185, 208, 216, 226, 23
8, 257, Pigment Violet 3, 19, 2
3, 29, 30, 37, 50, 88, Pigment Orange 13, 16, 20, 36, and the like.

Pigment green as a green pigment
7, 26, 36, 50, and as a yellow pigment, Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 3
5, 37, 55, 74, 81, 83, 93, 94, 9
5, 97, 108, 109, 110, 128, 137,
138, 139, 151, 153, 154, 155, 1
57, 166, 167, 168, 180, 185, 19
3. As the black pigment, Pigment Black 7, 28,
26 etc. can be used according to the purpose.

When the ink composition suitable for the hue of the cyan pigment of the present invention is applied to other hues, particularly, Pigment Red 122, Pigment Yellow 93, 94, 95 or 1
28 and Pigment Black 7 can be particularly preferably used.

As a coloring agent, a soluble dye (Solv
ent Dye) can also be used.

Further, any colorant such as an oil-based dye can be used as long as it is compatible with other ink components. Two or more types of colorants can be mixed and used as needed for color adjustment.

In order to further develop functionality in the ink composition of the present invention, various surface treatment agents, surfactants, viscosity reducing agents, antioxidants, antioxidants, crosslinking accelerators, ultraviolet absorbers, plasticizers , A preservative, a dispersant, a dye, and the like.

An appropriate amount of the pigment is 0.5 to 5% by weight, especially 0.7% by weight or more of the whole ink. Particularly desirable is 0.7 to 2% by weight. If the amount is less than 0.5% by weight, the saturation is insufficient. If the amount is more than 5% by weight, the ink viscosity characteristics are adversely affected, and the saturation is also reduced. It is well known that the amount of addition greatly affects the hue, and the hue angle H0 is a negative angle, particularly -12, for use as a cyan color.
A range of 0 to -90 ° is required, and the maximum saturation is C *
Is 40 or more, and particularly preferably 45 or more.

Furthermore, different shades may occur at the same dosage of the same pigment based on the specific interaction between the vehicle and the pigment. Further, the color tone varies depending on the particle size. The optimum mixing amount in the present invention is determined based on the above-mentioned optimum saturation, hue and light fastness in consideration of these effects. A major feature of the present invention is that a low melt viscosity at the time of use, for example, 15 mPa · s or less, can be ensured even at a high concentration with high chroma.

Various known pulverizing or dispersing devices 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, niche mill, kneader, mixer, colloid mill, stone mill, cable day 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 set variously 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. An appropriate rotation speed is 1,000 rpm or more. Particularly preferably, it is in the range of 2,000 to 4,000 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 temperature, which is not practical.

The material of the beads used for kneading 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. Therefore, 0.5 to 5 mmφ is appropriate, and particularly preferably 0.5 to 2 mmφ. The phthalocyanine pigment is liable to undergo crystal dislocation due to heat, mechanical impact, and interaction with a specific organic substance during kneading, causing a significant change in color tone, dispersibility, and the like. 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 ink jet 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
The range of １５15 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.

As the temperature at which the ink is melted during printing,
In order to make the apparatus simple and inexpensive, the range of 100 to 150 ° C. is optimal. The surface tension during melting is desirably 30 mN / m or less. It is desirable that the volume change upon transition from the molten state to the solid be 10% or less. Further, the ink composition of the present invention ejects ink droplets only when printing is necessary, a conventionally known inkjet printer, for example, an office printer, a printer used for industrial marking, a wide format printer, 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, and cloths. 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.

[0050]

Next, the present invention will be described in detail, but the present invention is not limited to the described examples.

Example 1 Alcohol-type wax as a vehicle (manufactured by Toyo Petrolite, trade name: UNILIN350)
80% by weight and 20% by weight of another alcohol-type wax (manufactured by Nippon Seiwa Co., Ltd., OX1949), and as a coloring agent, a cyan pigment belonging to Color Index Pigment Blue 15: 4 (manufactured by Dai Nippon Ink Co., Ltd.) Name: Fastogen
Blue 5410G) at a concentration of 0.5-5% by weight based on the total weight
In a variety of ranges, and 13 by a bead mill (Eiger motor mill M-250, beads: zircon 1φ).
Heating and kneading at 2,500 rpm until a homogeneous molten mixture is obtained at 0 ° C, followed by filtration under heating and pressure to remove impurities and the like. I got something.

These ink compositions were manually coated or put into an ink jet printer (JOLTSJO1A manufactured by Hitachi Koki Co., Ltd.) and printed on a recording medium. The chroma C * and hue H0 were measured using a color difference meter (# 90 manufactured by Nippon Denshoku). It was measured. The results are shown in FIG.

When the pigment concentration is less than 0.7% by weight, the saturation is low, and the desired saturation at which C * is 45 or more is 0.7% by weight.
Obtained above. Hue angle H0 is desirable -120 to -9
The pigment concentration at 0 ° was in the range of 0.7 to 3% by weight.

The melt viscosity at 130 ° C. of a pigment concentration of 1% by weight was measured using a rotational viscometer (EDL model manufactured by Tokimec) and found to be about 12 mPa · s. The printing with the ink composition containing 1.0% by weight of the pigment of the present example
A xenon lamp test device (Sutra made by Atlas) controlled so that the light amount at a wavelength of 340 nm is 0.35 W / m ²
nChex) for 100 h (sample temperature 60 ° C.) showed a good light fastness with a color difference ΔE of 0.8.

Example 2 Alcohol-type wax as a vehicle (manufactured by Toyo Petrolite, trade name: UNILIN425)
And a cyan pigment belonging to Pigment Blue 15: 4 as a colorant (manufactured by Toyo Ink, trade name: Lionol Blue FG)
-7400G: Example 2) or Pigment Blue 15: 3
Cyan pigments (manufactured by Toyo Ink, trade name: Lionol B
lue FG-7330: Heating and kneading using a device (motor mill) of Example 1 all 300 g of a mixture containing 1.0% by weight of Comparative Example 1) with respect to the total amount, respectively, until a homogeneous molten mixture is obtained. (3 hours), followed by filtration under heating and pressure to remove impurities and the like, followed by cooling at room temperature to obtain a homogeneous cyan ink composition. The rotation speed of the motor mill is 2,500 rpm.

[0056]

[Table 1]

The melt viscosity at 130 ° C. was 14 (Comparative Example 1) and 11 (Example 2) mPa · s in this order. As shown in Table 1, the pigment ink of Pigment Blue 15: 4 has good dispersion stability, C *: 53, H0: good cyan properties of -107 °, and ΔE *: 1.0 good light fastness. Pigment Blue 15: 3 ink, on the other hand, had remarkably poor dispersion stability and poor properties.

Incidentally, Pigment Blue 15 of this embodiment:
A further long-term xenon lamp light resistance test of the ink of No. 4 was performed,
The values of ΔE * were 1.0 (300 h) and 1.7 (500
h) A value of 2.7 (700 h) was obtained, confirming that the ink of the present invention was extremely excellent in light resistance.

Example 3 Alcohol-type wax as a vehicle (manufactured by Toyo Petrolite, trade name: UNILIN550)
50% by weight of an ester amide (manufactured by Kawaken Fine Chemicals, trade name: Kawaslip SA), and a cyan pigment belonging to Pigment Blue 15: 4 (Cyanine Blue 4933GN-EP manufactured by Dainichi Seika) as a colorant. A total of 300 g of a mixture containing 0.7% by weight based on the total amount was similarly prepared using the apparatus (motor mill) of Example 1, a stirring mill (dry / wet mill manufactured by Kurimoto Ironworks), and an attritor (MA01SC manufactured by Mitsui Mining). The mixture was heated and kneaded until a homogeneous molten mixture was obtained (3 hours), followed by filtration under heating and pressure to remove impurities and the like, and allowed to cool at room temperature to obtain a homogeneous cyan ink composition (Example 3) and An ink analog (Comparative Example 2) was obtained. The rotation speed of the stirring mill is 450 rpm, and the rotation speed of the attritor is 100 and 300 rp.
m. Motor mill speeds of 2,000, 2,500 and 4,000
rpm.

Each of the inks and ink analogs obtained was 12
The mixture was placed in a test tube of mmφ and left at 135 ° C. for 3 days. The separation of the ink layer (separation ratio is expressed in%) was observed, and the melt viscosity at 130 ° C. was measured in the same manner as in Example 1.

[0061]

[Table 2]

The results are shown in Table 2. The inks produced by the method of the present invention all showed a viscosity of 15 mPa · s or less and good dispersion stability, whereas the ink analogue produced at a low rotation speed showed a dispersion. The stability was poor, and significant separation of the ink layer was observed in each case.

Example 4 Alcohol type wax (manufactured by Nippon Seiwa, trade name: OX020T) and Kawaslip SA were used as vehicles, respectively, at 50% by weight and 30% by weight, and polyvinyl acetate (manufactured by Allied Chemical, trade name: AC401) ) To 20
% By weight, and Pigment Blue 15: 4 as a colorant
Treated cyan pigments (Lionol Blue, manufactured by Toyo Ink)
FG7405G) and a cyan pigment belonging to Pigment Blue 15: 3 as a comparative example (Lionol Blue FG735, manufactured by Toyo Ink)
0) or a mixture containing a treated cyan pigment belonging to Pigment Blue 15: 1 (manufactured by Sanyo Dyestuff Co., Colortex Blue P908) in an amount of 1.0% by weight based on the total amount, and a homogeneous molten mixture as in Example 1. , Kneading (about 6 hours), followed by filtration under heat and pressure to remove impurities and the like, and allowed to cool at room temperature to obtain a homogeneous cyan ink composition (Example 4) and two kinds of inks. An analog (Comparative Example 3) was obtained.

[0064]

[Table 3]

Table 3 shows the results of the same evaluation as in Example 1.
Shown in Pigment Blue 15: 1 pigment ink was strongly greenish and departed from the optimal cyan range. Pigment Blue 15: 3 pigment ink had insufficient separation stability and chroma characteristics. On the other hand, a print of the ink of the present invention belonging to Pigment Blue 15: 4 showed good light fastness with a color difference ΔE of 3 or less in the same xenon lamp irradiation test (100 h) as in Example 1.

EXAMPLE 5 UNILIN550 and OX1949 (manufactured by Nippon Seiwa) were each used as a vehicle in an amount of 50% by weight, and a cyan pigment cyanine blue 4927GP belonging to Pigment Blue 15: 4 was used as a coloring agent in an amount of 1% by weight. A total of 500 g of the mixture containing
Heating and kneading at 30 ° C. until a homogeneous molten mixture is obtained (about 6 hours), followed by filtration under heating and pressure to remove impurities and the like, and left to cool at room temperature to obtain a homogeneous cyan ink composition. Was. This ink composition was heated to 130 ° C., and the melt viscosity was measured as in Example 1. The average value measured 5 times is 1
It showed 0 mPa · s.

This ink was put into an ink jet printer in the same manner as in Example 1, and the ink was ejected from all the nozzles.
It was confirmed that even after being left in a molten state for a day, the fuel was sprayed without any problem. Further, as in Example 1, when the ink put in a test tube having a diameter of 12 mm was left at 135 ° C. while being melted, separation of the dispersion was not observed for one week. Example 1
ΔE * was 3 or less in the same light fastness test as in the above.

[Comparative Example 4] A mixture having the same composition as in Example 1 was mixed with a stirrer / mixer (Labo-Stirler LR-41B manufactured by Yamato, rotation speed).
At 100 rpm), the mixture was heated and kneaded (2 hours) to produce a cyan ink analog. This hot melt ink analog is
The mixture was heated to 30 ° C., and the melt viscosity was measured using a rotational viscometer as in Example 1. The average value measured 5 times is 9 mPa.s
showed that.

This ink analog was put into an ink jet printer in the same manner as in Example 1, and it was confirmed that the ink analog had been ejected. When the ink analogue was left in a molten state for 3 days and ejected again, it became impossible. When the number of nozzles was checked,
Injection failure occurred at 0% (50 nozzles). Furthermore, as in Example 1, when the ink analog placed in a test tube having a diameter of 12 mm was left at 135 ° C. while being melted, about 80% of an upper layer containing no colorant appeared on the upper part of the dispersion after one week. It was found that the solution separated into two layers.

Comparative Example 5 A homogenizer (manufactured by Hitachi Koki Co., Ltd.) was prepared by using a monoamide (Kemamide S-180 manufactured by Witco) as a vehicle and 1.5% by weight of a mixture of 1.5% by weight cyan pigment KET Blue111 (manufactured by Dainippon Ink) as a coloring agent. HG3
Heating and kneading at 130 ° C. until a homogeneous molten mixture is obtained according to 0), followed by filtration under heating and pressure to remove impurities and the like, and then allowed to cool at room temperature to resemble a homogeneous cyan ink. I got something.

The ink analog was heated to 130 ° C., and the melt viscosity was measured using a rotational viscometer as in Example 1. The average value measured five times was 20 mPa · s. When this ink analog was put into an ink jet printer and the ejection of the ink analog was examined in the same manner as in Example 1, the ink analog was ejected from all the nozzles at the initial stage. However, even if a higher voltage than usual was applied, the ejection failure occurred in about 20% (20 nozzles). Further, as in Example 1, the ink analog placed in a test tube having a diameter of 12 mm was left at 135 ° C. while being melted, and from the second day, about 50% of the upper layer containing no colorant was formed on the upper part of the dispersion.
It appeared that the liquid had separated to two layers.

[0072]

The hot-melt ink composition for ink-jet recording of the present invention achieves both dispersion stability and jetting characteristics, which have conventionally been problems when a phthalocyanine blue pigment is used as a coloring agent. Compared to the ink using a pigment as a colorant, the ink has excellent light resistance and can be used for a wide variety of purposes.

[Brief description of the drawings]

FIG. 1 is a diagram showing the molecular structure of a pigment as an example of the ink composition of the present invention.

FIG. 2 is a graph showing the relationship between pigment concentration and saturation and hue.

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Claims (5)

[Claims] An ink-jet hot melt ink composition for liquefying and jetting an ink composition which is solid at room temperature by heating to form recording dots on a recording medium for printing. Has a maximum chroma C * of 45 or more on a recording medium, the hue angle H0 at this time is in a range of -120 to -90 °, and the light amount at a wavelength of 340 nm is 0.35 W / m.
^When the xenon light of ² is irradiated for 100 hours, the color difference ΔE * is 3
A hot-melt ink composition for inkjet, which is characterized by the following. 2. The ink composition according to claim 1, wherein the ink composition contains a pigment belonging to Pigment Blue 15: 4 in a color index as a coloring material. 3. The ink composition has a hydroxyl value of 2
The hot-melt ink composition for ink-jet recording according to claim 1, further comprising 0 to 150 alcohol-type wax. 4. The ink composition according to claim 1, wherein said ink composition has a melt viscosity of 1 when printed.
4. The pressure is 5 mPa · s or less.
The hot-melt ink composition for inkjet according to the above. 5. The ink jet ink according to claim 1, wherein the ink composition is manufactured by kneading a pigment and a wax at a rotation speed of 2,000 rpm or more by a bead mill holding a high temperature. Hot melt ink composition.