JP2000248219A - Stealth type ink composition and recording using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a stealth type ink composition which does not limit a recording medium, enables high speed recordings, is mild for environments, and can solve troubles, such as insufficient adhesivity to recording media, low recording rates, and insufficient safety, in the cases of liquid ink jet recordings. SOLUTION: This hot melt type ink composition is used by thermally liquidizing the ink composition which is solid at room temperature, and then imparting any jet energy to the liquidized ink composition, thus allowing ink drops to jet on a recording medium to form recording drops. Therein, the ink composition contains a luminous substance which does not exhibit remarkable absorption in the visible light region but emits visible light, when irradiated with UV light, and uses an ink vehicle which does substantially not have an absorption peak in the range of 300-400 nm. The ink composition preferably contains one or more compounds selected from monoamides, ester amides and bisamides in an amount of >=50 wt.% based on the ink composition, and has a melting point of >=70 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stealth ink composition of a luminescent ink whose recording is determined by irradiation with ultraviolet rays, and a recording method, and more particularly to a hot melt ink composition and a recording method used in an ink jet recording apparatus. .

[0002]

2. Description of the Related Art It is widely practiced to mark various printed materials, bank checks, envelopes, packages, and the like with bar codes for maintenance and confirmation. In a specific method of this type of marking, a method is used in which printing is performed with a transparent or low-colored ink composition that cannot be observed with the naked eye, and detection is performed using a specific light beam, that is, ultraviolet light or infrared light. For this reason, a special ink composition called stealth-type ink or stealth printing is used. Regarding the method of performing this printing using an ink jet recording method, for example, JP-A-51-72509, JP-A-53-140105
No., JP-A-58-45999, JP-A-53-55214, JP-A-3-81
No. 376, JP-A-6-107992, JP-A-6-297883, JP-A-7
-188599, JP-A-8-239607, JP-A-8-239609, JP-A-8-253715, JP-A-9-131860, U.S. Patent 5,837,04
No. 2, U.S. Pat. No. 5,755,860, U.S. Pat. No. 5,366,252, and U.S. Pat. No. 5,093,147 have been reported.

On the other hand, as an ink composition for ink jet recording, a water-based or solvent-based liquid ink composition has been widely used, as seen in many of the reports described above. However, when the ink composition is recorded on paper that easily permeates, “bleeding” occurs, and the recording medium is limited to processed paper. In addition, even when recording on a plastic sheet, a special treatment is required for the surface because the drying property is poor particularly with an aqueous ink.

[0004] Therefore, as an ink composition that provides good print quality regardless of the paper quality, a hot melt ink composition using a wax or the like that is solid at room temperature is used.
There has been proposed a hot-melt ink jet recording system in which liquid is liquefied by heating or the like, jetted with some energy applied, cooled and solidified while adhering onto a recording medium to form recording dots. As a great advantage of this method, the ink composition is solid at room temperature, so that it is not stained during handling, and the amount of evaporation of the ink composition during melting can be minimized, so that there is no clogging of nozzles. Further, since the ink is solidified immediately after the attachment, there is no "bleeding", and various recording media such as Japanese paper, drawing paper, postcards and envelopes can be used without any pretreatment.

For example, JP-A-9-71743 and JP-A-9-3377
JP-A-8-165447, U.S. Pat.No. 5,350,789, U.S. Pat.No.5,703,145 illustrate these hot-melt ink compositions of various compositions, and JP-B-2,644,379 discloses one of the image forming agents. A hot melt ink composition using a fluorescent material and containing an ionomer component as an essential component is disclosed.

[0006]

However, in the stealth printing, recording media are diversified, and it is necessary to print at a high speed in order to process a large number of printed materials in a short time. Ink composition is used, fire,
There were many problems in environmental pollution. In addition, for example, in the case of an aqueous solvent-based ink composition that does not cause this problem, a large-sized drying device for drying in a short time is required, which may cause excessive dimensions, power consumption, and further damage to the recording medium. Sex was inevitable.

An object of the present invention is to provide a stealth-type ink composition and a recording method which can overcome these conventional problems, can perform high-speed recording, and have high storability and safety. Another object of the present invention is to optimize the composition and the method of use when applying a hot melt ink composition to the above problems.

[0008]

The gist of the present invention to solve the above-mentioned problems is to liquefy the ink composition at room temperature by heating and then apply some kind of jetting energy to form the ink composition droplets. The hot-melt type ink composition used to form recording dots by jetting onto a recording medium emits visible light when irradiated with ultraviolet light without showing significant absorption in the visible light region. , And a melting point of 70 ° C. or more.

The ink composition of the present invention preferably contains a luminescent substance which emits visible light upon irradiation with ultraviolet light, and uses an ink vehicle which does not substantially have an absorption maximum in the range of 300 to 400 nm.

[0010] More preferably, one or more of monoamide, ester amide and bisamide are used in the ink composition.
0% by weight or more is contained.

[0011] The ink composition of the present invention is useful in printing in which substantially invisible printing is performed on a colored substrate.

[0012]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, various waxes and resins used for hot melt type ink (sometimes called solid ink, solid ink or phase change ink) can be used without any particular limitation. . These include plant waxes such as candelilla wax, carnauba wax, wood wax, animal waxes such as lanolin, paraffin waxes, petroleum waxes such as microcrystalline wax, polyethylene wax, Fischer-Tropish wax, and stearin. Higher saturated or unsaturated fatty acids such as acids and behenic acid, ketones such as stearone and laurone, saturated or unsaturated fatty acid amides, saturated or unsaturated fatty acid esters, glycerides, saturated or unsaturated fatty acid ester amides, saturated or unsaturated aliphatic Alcohol, rosin resin, hydrocarbon resin, amide resin, polyester, polyvinyl acetate,
Acrylic and methacrylic polymers, styrene polymers, ethylene vinyl acetate copolymers, high molecular weight resins such as polyketones, silicones, and cumarone.

The hot melt type stealth ink composition of the present invention can be used by various conventional ink jet discharge methods without any particular limitation. As a method utilizing the deformation of the piezoelectric (piezo) element, various methods such as a bend mode, a push mode, a shear mode, and a combination thereof can be used. Also, by appropriately selecting the composition and the recording method, for example, Patent Publication 2,554,389, US Patent 5,593,486
, US Pat. No. 5,151,120 and the like, it is also possible to carry out bubble generation (bubble type) ink jet recording. Further, continuous ink jet recording described in U.S. Pat. No. 5,821,963 can be performed.

The melting point of the ink composition of the present invention must be 70 ° C. or higher. Here, the melting point is defined by JIS-K0064.

In order to make it difficult to visually discriminate the printed state as in the object of the present invention, it is necessary to minimize the penetration of the ink composition into the substrate immediately after the dot recording. In the case of a normal liquid ink composition, the surface tension and surface energy of the ink composition (contact angle to the substrate, interfacial tension)
The viscosity and the viscosity are important controlling factors. In the hot melt type stealth ink composition of the present invention, the solidification process of rapidly cooling is more important than these. After dot attachment, the ink composition loses fluidity within 1 to 10 m
s and completely solidifies in a short time of 1 s or less. During this time, the behavior of the ink composition penetrating into the substrate was examined, and it was experimentally confirmed that the melting point of the ink composition was the most dominant factor as compared with the melt surface tension, melt viscosity, and the like. In other words, the ink composition that slowly solidifies upon cooling, or conversely, the ink composition whose melt viscosity is slowly increasing, does not easily penetrate a substrate such as paper. The ink composition having a melting point of less than 70 ° C. penetrates into paper or the like before solidification, and shows a clear trace of an ink printed portion. Particularly, in a substrate such as colored paper, the difference in reflectance between the presence and absence of ink becomes remarkable as compared with a white or transparent substrate, making it easy to visually discriminate and achieving the object of the invention of stealth type printing. Can not. Although it is not particularly necessary to set an upper limit on the melting point of the ink composition of the present invention,
The melting point is 150 ° C. or less, especially 10
It is preferably 0 ° C. or lower.

The excitation wavelength for reading the stealth recording of the present invention is not particularly limited, and many electromagnetic rays including electron beams, X-rays, and particle beams can be used. Preferably, light is used. If the wavelength is less than 300 nm, the absorption of the hot melt type ink material tends to be excessive, and it is not possible to effectively utilize ultraviolet light for light emission. If the wavelength exceeds 400 nm, absorption in the visible light region is required for exciting the ink composition, which is unsuitable for coloring purposes.

As a light source, a continuous spectrum light source includes a deuterium lamp, a xenon lamp, a halogen lamp,
Light sources such as low-pressure, high-pressure and ultra-high-pressure mercury lamps, mercury xenon lamps, hollow cathode lamps,
As a metal halide lamp and a pulse light source, a xenon flash lamp, a nitrogen laser, an excimer laser and the like can be used.

The emission wavelength is appropriately selected from infrared light, near-infrared light, visible light, and the like according to the characteristics of the sensing element or device. In particular, visible light, that is, a wavelength of 400 to 750 nm is used. Is preferred. In a region outside this wavelength range, special consideration is required for the detection element or device. In the visible light range, various wavelengths such as blue, green, orange, red, and yellow, and mixtures and intermediate colors thereof are detected according to the purpose.

As described above, various waxes can be used in the stealth ink composition of the present invention without limitation.
In particular, it is desirable that the ink composition, which does not substantially have an absorption maximum in the range of 300 to 400 nm, particularly contains a wax selected from monoamide, ester amide and bisamide, preferably at least 50% by weight. It is not clear why these materials exhibit particularly favorable properties, but (1)
Form a transparent and uniform ink composition to absorb light in the visible range,
(2) It has an appropriate glass transition point (softening point), melting point (flow starting temperature), and surface tension (surface energy, contact angle), and can perform good recording on many recording media. (3) Good compatibility with respect to the compatibility and dispersibility with the luminescent material, and excellent compatibility between the components, and thus, items such as good transparency were recognized. In particular, if the softening temperature is inappropriate, for example, if the temperature is too low, unnecessary penetration into a recording medium such as paper occurs, or if the temperature is too high, solidification is rapid, and ink dots do not adhere to the recording medium. Is generated.

(4) Each of these waxes is an aliphatic organic compound.
There is a common feature that the absorption maximum based on the π-electron conjugate system is not present at 00 to 400 nm. On the other hand, ionic polymers,
For example, ethylene-methacrylic acid copolymers and the like are practically liable to cause problems in water resistance, and metal ion components serving as counter ions of free ions are likely to cause electrochemical defects such as corrosion to the inkjet head portion. Not preferred.

(5) In addition to the above-mentioned features, (5) since it has a relatively high melting point, penetration into a substrate immediately after dot printing is slightly suppressed.

Hereinafter, specific examples of the wax used in the present invention will be described.

As fatty acid amides, monoamides, bisamides, tetramids and the like are used. For example, lauric amides and alkyl amides, stearic amides and alkyl amides, oleic amides and alkyl amides, erucic amides and alkyl amides, ricinoleic amides and alkyl amides, stearic amides, palmitic amides and alkyl amides, behen N-substituted fatty acid amides such as acid amides and alkyl amides, brassic acid amides and alkyl amides
-2-hydroxystearic acid amide, N, N'-ethylenebisoleic acid amide, N, N'-xylenebisstearic acid amide, stearic acid monomethylolamide, N-oleylstearic acid amide, N-stearylstearic acid amide, N-oleyl palmitic acid amide, N-stearyl erucic acid amide, N, N'-dioleyl adipamide, N, N'-dioleyl sebacic amide, N, M'-distearyl isophthalic amide, 2-steel Aramid ethyl stearate and the like are selected. Particularly, fatty acid alkylamides are preferably used. Fatty acid amides and alkylamides have low melt viscosities at around 100 ° C., and have a remarkable effect of lowering the melting point of the ink composition and lowering the viscosity during melting.

The polyamides are preferably polyamides based on dimer (dimer) acid. Optimally, the base acid is oleic, linoleic, linoleic or eleostearic acid.

Specifically, amide resins such as versamide 711, versamide 725, versamide 930, and versamide 94
0, Bar Salon 1117, Bar Salon 1138, Bar Salon 1300
(Made by Henkel), Tomide 391, Tomide 393,
Tomide 394, Tomide 395, Tomide 397, Tomide 509, Tomide 535, Tomide 558, Tomide 560, Tomide 1310, Tomide 1396, Tomide 9
0, Tomide 92 (Made by Fuji Kasei), KTR2150 (Made by Kao) as polyester, Macromelt 6030, Macrome
lt 6065, Macromelt 6071, Macromelt 6212, Macromelt
6217, Macromelt 6224, Macromelt 6228, Macromelt 2
38, Macromelt 6239, Macromelt 6240, Macromelt 630
1, Macromelt 6900, DPX 335-10, DPX H-415, DPX 335-
11, DPX 830, DPX 850, DPX 925, DPX 927, DPX 1160,
DPX 1163, DPX 1175, DPX 1196, DPX 1358 (Henkel White Water), SYLVAMID E-5 (Arizona Chemical), UNIIREZ 222
4, UNIREZ 2970 (Union Camp), AC401, AC540, AC580 (all made by Allied Chemical) etc. can be used as polyvinyl acetate.

As the vehicle, at least one kind selected from these, or a mixture of two or more kinds can be used. All of these have good wettability to a recording medium and exhibit high adhesive performance. Further, it has excellent adhesion to a wide variety of adherend substances.

The ink composition of the present invention has a melt viscosity at a temperature used for printing of up to 50 mPa · s, preferably 5 to 30 mPa · s.
Pa · s is desirable. If the viscosity is less than 5 mPa · s, sedimentation of the luminescent agent cannot be prevented, and if the viscosity exceeds 50 mPa · s, it is difficult to perform ink jet recording.

The heating temperature is desirably 70 ° C. or higher, preferably 100 to 150 ° C. In the case of an ink composition having a low viscosity at a melting temperature lower than 70 ° C., sufficient mechanical strength cannot be secured when left at room temperature, and an excessive load on the apparatus is required to maintain a temperature higher than 150 ° C.

In the present invention, a luminescent substance which emits ultraviolet light may be used. This includes fluorescent and phosphorescent substances, such as U.S. Pat. No. 5,755,860, U.S. Pat.
Various light-emitting materials disclosed in U.S. Pat. No. 37,042 and US Pat. No. 5,256,139 can be used without any particular limitation. In addition, acriflavine used for laser dyes, fluorescein-based and rhodamine-based fluorescent dyes, The Society of Dyers and
Fluoresce in “Color Index” edited by Colorants
Color materials classified as nt Brighteners (fluorescent brighteners) can be suitably used. These include stilbene, thiazole, coumarin, naphthothiazole, triazole, xanthene, naphthalimide, triazine,
There are various compounds such as morpholine, pyrazolone, azole, oxazole, azacyanine, pyrazoline, acenaphthene, benzimidazole and benzoxazole.

Further, rare earth elements and their organic chelate complexes used as light emitters of CRTs and the like are also suitably used for the purpose of the present invention. As rare earths, Sc, Y, La,
Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, D
There are y, Ho, Er, Tm, Yb, and Lu. Further, as an element which emits light by forming a complex, Al, B, Be, C
Typical examples include d, Ga, Li, Mg, Mo, Sb, U, W, and Zr.

The ring-opening and cyclic chelating ligands used in the complex include alkylpolyamines, 2,2'-bipyridines,
1.10-phenanthroline, aromatic polyamine, amino alcohol, amino acid, peptide, polyamino polycarboxylic acid, 1,3-diketone, oxime, Schiff base, phenol, 1,2-dithiolen, Dithioorbamine, xanthic acid, dithiocarboxylic acid,
There are thiol type, phosphine, arsine, selenide type, saturated and unsaturated cyclic polyamine type, porphyrin type, phthalocyanine type, borane type, carborane type and the like.

Specifically, acetylacetone, morin, oxine, pontachrome blue black R, flavonol, amino-4-hydroxyanthraquinone, benzoin, cochineal, quinizarin, 2-methyloxin,
2-hydroxyphenyl-benzoxazole, eriochrome red B, superchrome garnet Y, eriochrome red B, rhodamine B, 5,7-dichlorooxin, 5,7-dibromoxin, benzoylacetone,
Examples include dibenzoylacetone, salicylic acid, and dibenzoylmethane. As these metal complexes, for example, compounds described in Chemical Chemistry Course, Vol. 17 and 18, edited by The Chemical Society of Japan, Maruzen (published in 1991) and the like can be used.

Fluorescent or EL (electroluminescence) powder, for example, Y ₂ O ₃ S: Eu, ZnS: Cu: A
1, ZnS: Ag, ZnO: Zn, (ZnCd) S: A
g, ZnS: Mn: Cu, ZnS: Cu, ZnB: Cu
Etc. can also be used.

Specific examples of the luminescent agent include coumarin photosensitizers NKX-846, 1297, 1319, 1595, 1858, and 125.
3, 1658, ketocoumarin-based NKX-653, 1792, 1880, styryl-based NK-1819, 1886, 3390, dicyanomethylene (DCM) -based NK-1473, 1474, cyanine-based NK-2911, 443
2, 4489, NKX-1317, 1318, 131 which are dyes for laser oscillation
6, 1767, 1768, 1320, 1769, 1319, 1770, 1771 (all manufactured by Japan Photographic Dye Laboratories), PBBO, BBOT, BBO, DPH, PPO, DPS, PBD, POPOP TP
B, butyl-PBD, α-NPO, p-terphenyl, p-quarterphenyl (manufactured by Dojindo or Wako Pure Chemical Industries), EB-501, EG
-502, ER-120 (Mitsui Chemicals), LUMILUX-C, RedCD10
5, RedCD106, RedCD120, RedCD131, RedCD316, RedCD33
1, RedCD332, RedCD335, RedCD339 (all made by Clariant), CALCOFLUOR WHITE LD, CALCOFLUOR WHITE RAP, C
ALCOFLUOR WHITE RW (above manufactured by BASF), UVITEX-OB (manufactured by Ciba Specialty Chemical), Eu (TTA) ₃ Phen (manufactured by Dojinato), ULTRAPHOR RN LIQUID (manufactured by Mitsui-BASF dye) and the like.

In the recording method of the present invention, heating, pressurizing, and electromagnetic radiation (ultraviolet rays, infrared rays, electron beams, microwaves, etc.), which are usually performed, are used after the recording step, and are used for processing the ink composition. It is desirable not to use a processing step in terms of high-speed recording and low-power operation. The dots recorded by the inkjet can be used without any processing.

The present invention is effective only when the printing speed is high. In particular, 10 ips (inch / inch)
Seconds) or more. In a recording method having a post-process or a recording speed of less than 10 ips, the features of the present invention are not fully utilized. For this purpose, the stealth ink composition and the recording method of the present invention are:
It is particularly preferable to use a line-type head and a recording method, that is, a recording method that does not move back and forth in the direction perpendicular to the traveling direction (shuttle type).

The appropriate amount of the compound that emits light upon irradiation with ultraviolet rays is 0.01 to 5% by weight based on the total amount of the ink composition. Particularly desirable is 2% by weight or less.
If the amount is less than 0.01% by weight, the emission intensity is reduced. If the amount is more than 5% by weight, the recording is exposed during non-irradiation due to coloring or the like, and the viscosity characteristics of the ink composition are adversely affected. 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 pigment, a dye and the like can be mixed.

[0038] The preparation of high quality ink compositions requires a balance of many important factors. The ink composition of the present invention satisfies several well-known requirements for application to a hot-melt ink jet printer. That is, the ink composition has sufficient hardness and stability at room temperature, and has a reliable storage quality before printing and an 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. These requirements are complex and cannot always be clearly quantified for the ink composition of the present invention, but for example, a hot melt ink composition having a relatively low melting point is typically liable to bleed and cause offset. It's easy to do. Even when stored at 40 ° C., it is necessary that offset does not occur in a state where printed matters are stacked. However, when the melting point of the ink composition is high, the viscosity increases. However, the melt viscosity at the time of printing is preferably 50 mPa · s or less, particularly 5 to 30 mPa · s. 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 1
0,000Pa · s or more.

Regarding the bending characteristics of the printed matter, it is desirable that the test pass a test of 5 mmφ or less, particularly 3 mmφ or less in a mandrel test using a plastic film.
The temperature at which the ink composition is melted during printing is optimally in the range of 100 to 150 ° C. in order to make the apparatus simple and inexpensive. The surface tension at the time of melting is desirably 40 mN / m or less. 10% volume change when transitioning from a molten state to a solid
The following is desirable.

The stealth-type ink composition and recording method of the present invention eject ink composition droplets only when printing is required (on-demand type), conventionally known ink jet printers, such as office printers and industrial printers. It can be used for printers used for marking, wide format printers, super wide and grand format printers, printing 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. Absent. 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. In particular, the composition and the recording method can be used for many well-known industrial inkjet printers and marking devices as particularly suitable applications. These include a wide variety of articles and their packaging, containers, packs, bottles, bags, including sheets and bulk of ordinary media, ie, paper, treated paper, high quality paper, plastic, metal, fabric, glass, etc. , For example, juice,
Beer and other beverages, dairy products, bread and other foods, shampoos,
It can be used for marking on cosmetics such as detergents, pharmaceuticals, chemicals, and electric / electronic devices. It can also be used for printing on textiles such as fabrics and cloths. Particularly suitable for printing on colored media. Furthermore, marking of cards, label making devices, pillow wrapping machines, postal address sorting devices, postal code printing machines, business card making machines, securities such as bank checks, important documents etc. or paintings, monuments, cultural assets etc., It can be used for direct mail creation devices, etc. Various printing or processing apparatuses combining the ink composition and the recording method apparatus of the present invention with an exposure apparatus and a detection apparatus are also possible.

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to the examples. Example 1 As a vehicle, 75 parts by weight of an ester amide (manufactured by Kawaken Fine Chemicals: Kawaslip SA), 5 parts by weight of a polyamide (manufactured by Henkel Hakusui: DPX-H415), and 20 parts by weight of rosin (Arakawa Chemical: Pinecrystal KE100). Of a mixture containing 0.1 parts by weight of a red light-emitting agent (manufactured by Mitsui Chemicals, Inc .: ER-120) were heated and kneaded (about 30 minutes) at 130 ° C. until a homogeneous molten mixture was obtained. The mixture was filtered under heating and pressure to remove impurities and the like, and allowed to cool at room temperature to obtain a homogeneous hot melt ink composition.

For comparison, a comparative composition was prepared by the same composition and kneading step except for the luminescent agent alone.

The ink composition does not exhibit substantially strong light absorption in the visible region. Further, the comparative composition did not show substantially strong absorption not only in the visible region but also in the ultraviolet region of 300 to 400 nm.

The melting point of the ink composition prepared by using a melting point measuring device (MP-S3 manufactured by Yanagimoto Seisakusho) was from 76 to 8.
It was 0 ° C. The ink composition was heated and melted at 130 ° C., and the melt viscosity was measured using a rotational viscometer (EDL model manufactured by Tokimec). The average value measured five times is 7.9 mPa · s
showed that.

A solid ink jet printer (manufactured by Hitachi Koki: direct printing plate printer SJ0) was used for the ink composition.
The test pattern was printed on plain paper (Xerox 4024 paper) in a high-speed printing test apparatus (resolution: 600 dpi) using a piezoelectric element push mode head portion of 2A). The printing speed (paper running speed) varied in the range of 10 to 200 ips, but in all cases, the printing condition was good and exhibited abrasion resistance immediately after printing, and penetration into paper, peeling, light scattering, and other defects. Was not observed at all.

Immediately after printing, the black lamp (U
VP: Model UVM-57)
Good red-orange emission (maximum emission of about 615 nm) was observed. This printed matter did not substantially absorb or scatter in the visible light range, and was difficult to visually observe unless irradiated with ultraviolet light. Example 2 50 parts by weight of an ester amide (Kawaken Fine Chemical: Kawaslip SA) as a vehicle, E
5 parts by weight of VA (manufactured by Henkel Hakusui: Q007), 45 parts by weight of rosin (manufactured by Arakawa Chemical: Pinecrystal KE100), and a blue light-emitting material (manufactured by Ciba Specialty Chemicals: UVIT)
EX-OB) Heating and kneading 0.01 parts by weight until a homogeneous molten mixture is obtained, followed by filtration under heat and pressure to remove impurities and the like, and then left to cool at room temperature to obtain a homogeneous hot melt ink composition. I got

In the same manner as in Example 1, a comparative mixture was prepared in the same manner as described above except that no luminescent agent was added.

As in Example 1, the melting point of the ink composition
When the melt viscosities were measured, each was 74 to 79 ° C., and 12.
It was 2 mPa · s.

The ink composition substantially did not show strong absorption and scattering in the visible region, and the comparative mixture did not show strong absorption not only in the visible region but also in the region of 300 to 400 nm.

The ink composition was placed in the same ink jet printer test apparatus as in Example 1 and left in a molten state for 3 days to perform jetting. As a result, it was confirmed that all the inks were jetted without any problem. The printing speed was changed in the range of 10 to 200 ips, and the substrate was plain paper, colored Kent paper (manufactured by Lintec:
New color blue, red, black) and PVC coated sheets (manufactured by Ewa Shoko: BPV-01-T) were used. Under any of the conditions, the printing condition was good and the abrasion resistance was exhibited immediately after printing, and no permeation to the substrate, peeling, light scattering, and other defects were observed at all.

When irradiated with ultraviolet rays in the same manner as in Example 1,
In each of the print samples, clear blue light emission (emission maximum of about 437 nm) was observed. These prints, including colored Kent paper, did not exhibit substantial absorption or scattering in the visible light range, and were difficult to visually observe unless irradiated with ultraviolet light. Example 3 Monoamide (Witco
55 parts by weight, manufactured by Kemamide S-180, 15 parts by weight of bisamide (manufactured by Nippon Kasei: Slipax-O), 20 parts by weight of polyamide (manufactured by Henkel Hakusui: DPX335-10), hydrocarbon wax (manufactured by Arakawa Chemical: Alcon P-) 70) 10 parts by weight and a red luminescent agent (manufactured by Dojin Chemical: chelate complex Eu (TTA) ₃ Phen)
500 g of a mixture containing 0.1 parts by weight of
Then, the mixture was heated and kneaded until a homogeneous molten mixture was obtained, followed by filtration under heating and pressure to remove impurities and the like, and allowed to cool at room temperature to obtain a homogeneous hot melt ink composition.

Similarly, a comparative mixture was prepared in the same manner as described above except that no luminescent agent was added.

The melting point and melt viscosity of the ink composition were measured in the same manner as in Example 1.
mPa · s. The ink composition substantially did not show strong absorption and scattering in the visible region, and the comparative mixture did not show strong absorption not only in the visible region but also in the region of 300 to 400 nm.

A test pattern is printed on a colored paper and a colored film (polyethylene) by placing the ink composition in a solid ink jet printer (manufactured by Hitachi Koki: JOLT-SJO1A), and emits a good red light when irradiated with ultraviolet rays. It was confirmed. This printed matter did not substantially absorb or scatter in the visible light range, and was difficult to visually observe unless irradiated with ultraviolet light. Example 4 50 parts by weight of an ester wax (manufactured by Cerarika Noda: deodorized purified carnauba wax No. 1) and 50 parts by weight of an aliphatic amide (manufactured by Witco: Kemamide S-180) as a vehicle, and blue as a luminescent agent A total of 500 g of a mixture containing 2 parts by weight of a luminous body (manufactured by Nilaco: red phosphor Y ₂ O ₃ S: Eu) is heated at 140 ° C. by a stirring mill (manufactured by Kurimoto) until a homogeneous molten mixture is obtained. , Kneading (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 hot melt ink composition.

As in Example 1, the melting point of the ink composition
When the melt viscosities were measured, each was at 80 to 85 ° C and 12.
It was 2 mPa · s.

The composition was placed in an ink jet printer in the same manner as in Example 3 and printing was performed, and it was confirmed that the composition emitted a good red light when irradiated with ultraviolet light using a black light. This printed matter did not substantially absorb or scatter in the visible light range, and was difficult to visually observe unless irradiated with ultraviolet light. Example 5 Esteramide (CP H
All, 50 parts by weight of trade name: CPH380N), 28 parts by weight of EVA-based wax (Henkel Hakusui: Q5007), and 2 parts of polyethylene wax (Nippon Seisen: WEISSEN 252C)
8 parts by weight, 10 parts by weight of microcrystalline wax (manufactured by Nippon Seiwa: Hi-Mic 1070) and a green luminescent material (Mitsui Chemicals: EG-502) or a red luminescent material (Clariant: LUMILUX CD331) as a luminescent agent Two types of mixed compositions were prepared by mixing 0.1 parts by weight of each. 500 g of the mixed composition
130 ° C by motor mill (manufactured by Eiger Japan)
Then, the mixture was heated and kneaded until a homogeneous molten mixture was obtained, followed by filtration under heating and pressure to remove impurities and the like, and allowed to cool at room temperature to obtain two homogeneous hot melt ink compositions.

The melting point of the ink composition was measured in the same manner as in Example 1. 13
The melt viscosity at 0 ° C. was 12.0 mPa · s in each case.

The composition was placed in an ink jet printer in the same manner as in Example 3 and printing was performed, and it was confirmed that green or red light was satisfactorily emitted by irradiation of ultraviolet rays with a black light. These printed materials did not show substantial absorption or scattering in the visible light region, and were difficult to visually observe unless irradiated with ultraviolet light. [Comparative Example 1] ZnS: Cu: Al (manufactured by Nilaco) 3 parts by weight as a luminescent agent, dispersant (manufactured by Kao: Emulgen A-90)
0.5 parts by weight, resin content (manufactured by Nippon Polymer: W-251:
A homogeneous dispersion of 0.3 parts by weight of an acrylic resin emulsion having a solid content of 40%, 0.1 parts by weight of monoethanolamine, 10 parts by weight of diethylaminoethanol, 0.03 parts by weight of EDTA, and 85 parts by weight of ion-exchanged water can be obtained. The mixture was dispersed and kneaded until then, followed by filtration to remove impurities and the like, to obtain a comparative composition.

This comparative composition exhibited a viscosity of 4.5 mPa · s. The liquid has a melting point below room temperature.

The composition was placed in an ink jet printer in the same manner as in Example 3, and printing was performed on plain paper without heating. After drying, it was confirmed that the composition emitted green light when irradiated with ultraviolet light using black light. However, since the drying of the ink composition is remarkably slow, the printed portion does not show resistance to rubbing, and hot air drying (80
° C) also took several minutes. When the heating and drying process was not used, several hours were required. [Comparative Example 2] 0.1% by weight of UVITEX-OB as in Example 1 was mixed with dipropylene glycol methyl ether (manufactured by Dow Chemical: Dowanol DPM) as a luminescent agent, and the mixture was stirred until a homogeneous dispersion solution was obtained. Subsequently, filtration was performed to remove impurities and the like, to obtain a comparative composition.

This comparative composition had a viscosity of 3.8 mPa · s. The liquid has a melting point below room temperature.

The composition was placed in an ink jet printer in the same manner as in Example 3 and printing was performed on plain paper without heating, and it was confirmed that the composition emitted green light when irradiated with ultraviolet light using black light. However, the drying of the printed part is extremely slow, so that the printed part bleeds due to penetration into the paper,
It took several minutes to show resistance to rubbing even with hot air drying (80 ° C.). When the heating and drying process was not used, several hours were required. Comparative Example 3 Fatty acid-based wax (Uni) was used as a vehicle.
Chem: Prifrac2942), 50 parts by weight of alcohol wax (NPS-9125, manufactured by Nippon Seisaku) and 0.01 part by weight of UVITEX-OB as in Example 2 are mixed to obtain a homogeneous dispersion solution. Then, the mixture was stirred at 130 ° C. and filtered to remove impurities and the like to obtain a comparative composition.

As in Example 1, the melting point of the ink composition
When the melt viscosities were measured, each was 54 to 63 ° C. and 8.4.
mPa · s.

The composition was placed in an ink jet printer and printed on colored paper in the same manner as in Example 3. Although the comparative ink composition was almost transparent in the visible range, the penetration of the recording dots into the substrate was remarkable, and the printed portions could be clearly distinguished visually.

[0065]

According to the stealth ink composition and the recording method of the present invention, problems such as insufficient adhesiveness to a recording medium, low recording speed, and safety, which have conventionally been problems in the case of liquid ink jet recording, are solved. , Does not limit the recording medium,
It has become possible to provide a high-speed recordable, environmentally friendly ink composition and a recording method. Further, stealth-type printing that cannot be visually discriminated can be performed on a colored substrate.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C056 EA01 EA11 EA19 EE17 FA03 FA04 FA05 FA13 FB01 FB03 FB04 FB08 FB09 FB10 FC02 FD02 FD07 2H086 BA01 BA02 BA54 BA55 BA60 BA62 4J038 BA211 BA231 CB1 CM031 DD03 JA16 JA33 JA38 JA53 JB12 JB13 JB14 MA12 NA19 NA23 NA26 NA27 PA15 PA17 PB11 4J039 AB08 AB12 AD01 AD03 AD08 AD09 AD10 AD12 AD19 AE01 AE11 BC20 BC36 BE33 CA09 EA10 EA27 EA43 EA44 EA47 GA24

Claims (4)

[Claims] 1. A hot ink used for forming recording dots by liquefying an ink composition which is solid at room temperature by heating and then applying some ejection energy to eject ink droplets onto a recording medium. In a melt-type ink composition, the ink composition emits visible light when irradiated with ultraviolet light without exhibiting significant absorption in the visible light region,
And a melting point of 70 ° C. or higher. 2. The stealth type according to claim 1, wherein the ink vehicle contains a luminescent substance which emits visible light upon irradiation with ultraviolet light and has substantially no absorption maximum in the range of 300 to 400 nm. Ink composition. 3. An ink composition containing at least one of monoamide, ester amide and bisamide in an amount of 50% by weight or more of the ink composition.
3. The stealth ink composition according to item 2. 4. The recording method for a stealth-type ink composition according to claim 1, wherein printing is performed on a colored substrate so as to be substantially indistinguishable to the naked eye.