JP5363331B2 - Fluorescent liquid ink composition for inkjet printing - Google Patents

Abstract

Ink composition which is invisible to the naked eye, which is fluorescent, for inkjet printing, and which is liquid at ambient temperature, comprising: a) a binder, comprising at least 0.5% by weight, with respect to the total weight of the ink, of at least one thermoplastic polyamide resin, soluble in ethanol; b) a solvent comprising at least 10% by weight, with respect to the total weight of the ink, of one or more organic solvent compound (s); c) at least 0.05% by weight, with respect to the total weight of the ink, of one or more dye(s) and/or pigment (s) which is (are) invisible to the naked eye and which is (are) fluorescent in the visible region only when they are exposed to ultraviolet light and which are chosen from rare earth metal chelates and rare earth metal complexes; d) less than 10% by weight of water, with respect to the total weight of the ink. Marking process, substrate and method for identifying items.

Description

  The present invention relates to fluorescent ink compositions for marking substrates, substrates, and all types of goods, the nature of which is greatly enhanced by both “continuous inkjet” technology and “drop-on-demand” technology. It is particularly suitable for inkjet marking or printing of a wide variety of supports, substrates and articles (whether porous or non-porous).

  More particularly, the ink composition according to the present invention is colorless when illuminated by visible light, is not visible to the naked eye, and is fluorescent under UV light, ie, visible light when irradiated with ultraviolet light. It is an ink composition that emits light.

  For this reason, the ink composition according to the present invention automatically reads all porous or non-porous supports in a manner invisible to the naked eye, such as a security code, bar code, or postal index code reader. Very particularly suitable for marking as codes that can be read by the device.

  Inkjet printing prints various types of items on a variety of items, such as barcodes, expiration dates, etc., even on non-planar supports at high speed and without the items contacting the printing device. A well-known technique that allows marking or decorating.

  Inkjet printing systems are divided into two main types: a “drop on demand” (DOD) type and a “continuous inkjet” (CIJ) type.

  In the deflected continuous ink jet ejection, the ink is transferred into the cavity including the piezoelectric crystal under pressure, and the ink flows out from the cavity through the orifice (nozzle) in the ejection form. Piezoelectric crystals that vibrate at a predetermined frequency cause pressure disturbance in the ink jet, and the ink jet vibrates and gradually splits into spherical droplets. Electrodes placed on the jet path, where the jet breaks into droplets, make it possible to impart an electrostatic charge to these droplets if the ink is conductive. The droplets thus charged are deflected in the electric field to allow printing. The droplets that were not charged and consequently not deflected are collected in the gutter and the ink is absorbed and then reused in the ink circuit.

  This type of continuous inkjet ink ejection provides markings without touching and can change the display at will, with fast forward progression on items that do not need to be flat.

  This technique is particularly suitable for marking and identification of industrial products on the production line (expiration date, serial number, batch number, barcode, etc.) or sorting of postal letters and parcels.

  Postal sorting requires ink on both porous supports such as letter paper and non-porous or slightly porous supports such as magazines and other paper plastic packaging films delivered by mail. And

  “Drop-on-demand” jet injection can be performed by “bubble” jets or by “piezoelectric” jets. In the former, the ink is vaporized in the vicinity of the nozzle, and this vaporization causes ejection of a small amount of ink positioned between the resistance for vaporizing the ink and the nozzle. In the latter, a sudden change in pressure caused by an actuator set operating by electrical excitation of a piezoelectric crystal or ceramic placed in the vicinity of the nozzle causes the ink droplets to be ejected.

  The nozzle diameter in the DOD jet is on the order of 10 to several tens of microns. For continuous inkjet, the nozzle diameter is larger, on the order of 30 to 100 microns.

  Ink compositions suitable for jetting are inherent in this technology, in particular viscosity, solubility in cleaning solvents, compatibility of raw materials, appropriate wettability on the substrate to be marked, etc. In some cases, some criteria for conductivity must be met.

  In addition, these inks dry quickly and can flow without clogging in the vicinity of the nozzle, or can remain stationary, and the jetting direction must be very stable, Allows the printer head to be prepared for cleaning.

  These inks must be carefully formulated and filtered so that they do not contain particles of a size that can clog the nozzles. Filtration with a threshold between 0.2 and 1 μm is generally performed.

  The current ink raw material in the deflection continuous ink jet type ink jet is made of an organic substance or an inorganic substance, and one or more volatile solvent or water, although there are one or more kinds of coloring materials such as pigments or pigments, resins or binders. One or more salts, optionally introducing conductivity, as well as various additives.

  Current ink raw materials for drop-on-demand (DOD) ink jets are also organic or inorganic, one or more of volatile solvent or water to varying degrees of dye or pigment, resin or binder. Although it is a solution and the ratio is different from that of deflection continuous inkjet ink, it does not require electrical conductivity.

  The coloring material is a dye or pigment and may be soluble or insoluble in the solvent used.

  As a result, pigments that are inherently insoluble are dispersed and can be opaque or transparent. They contribute to the ink with certain optical properties such as color, opacity, or fluorescence (US Pat. No. 4,153,593, US Pat. No. 4,756,758, US Pat. No. 4,880,465). Description, European Patent No. 0289141, US Pat. No. 5,395,432, German Patent No. 2298713). In some cases, the dye itself contributes sufficient conductivity to the ink, in which case there is no need to add a conductive salt. C. I. The dyes known under the names Solvent Black 27, 29, 35 and 45 apply in this case.

  Inks for postal sorting applications are generally fluorescent when illuminated under visible light or by ultraviolet light so that they can be read by an automated system that performs very fast readings and identifies and automatically sorts them. It is. It can be seen with the naked eye and is generally orange to be easily found by postal operators. When the surface of a mail piece, such as a letter or parcel, has an excessively strong color, this interferes with the fluorescent dye of the ink and the fluorescence is reduced to the point where the marking no longer fluoresces enough to be automatically detected and read. Is done.

  Some of the invisible marking systems aimed at combating counterfeiting are also based on colorless ink that is invisible to the naked eye but becomes visible under UV irradiation.

  Some inks contain optical brightener-type dyes that absorb UV light and emit a bluish visible light. When such ink is placed on white paper, competition between the paper optical brightener and the ink makes it difficult to find the ink.

  Some other systems are based on inks that contain dyes that absorb less in the visible spectrum but produce absorption and fluorescence in infrared light. These systems require special equipment to be detected because infrared light emission is not visible to the naked eye.

  Thus, in mail sorting, there is a specific need for fluorescent inks that are less sensitive to the color of the support so that the level of reading is better for safety applications compared to colored inks. . More specifically, visible light that is visible to the naked eye under UV irradiation and thus emits visible light under UV irradiation, but has a wavelength different from that in optical brighteners commonly used in paper. There is a need for ink that emits light.

  Colorless and invisible dyes that absorb UV radiation under UV irradiation and emit visible light with longer wavelengths compared to optical brighteners are rare earth metal chelates. These well known dyes are commercially available, for example from Honeywell. These dyes absorb UV radiation to re-emerge visible light, for example, about 610-620 nm with europium chelates, or about 490-580 nm with dysprosium chelates.

  However, due to the strong absorption of ultraviolet light, these dyes can be decomposed by light without any visible color change, that is, without knowing, and the stability of fluorescence is greatly affected. Is done.

  Further, due to ink recirculation in deflection continuous ink jet type printers, the ink is constantly in intimate contact with the surrounding air. The stability of these rare earth metal complexes can be affected by this contact with air. As a result, the fluorescence may be lost completely.

  Thus, there is a particular need for ink, stability over time, and stability during continuous operation in the printer sufficient for the ink to retain its intrinsic fluorescent properties.

  Binders or resins generally occupy most of the solid and polymer components, and their choice depends on solubility in the chosen solvent and on compatibility with dyes and other additives, and especially on dryness. It is determined by the properties that contribute to the post-ink film (US Pat. No. 4,834,799, German Patent 2,286,402, US Pat. No. 5,594,044, US Pat. No. 5,316,575, WO 96/23844). No., WO 95/29287).

  Their primary function is to contribute to the adhesion of the ink to the maximum number of supports or to a specific support, such as a non-porous support. They also make it possible to provide a suitable viscosity for the formation of droplets starting from a jet against the ink, and most of the resistance to physical and / or chemical effects in the ink or rather the resulting marking Contribute to.

Additives include:
-Plasticizer, softened dry ink film, can improve adhesion and adhesion of the ink on the marked support.
・ Dispersants and pigments can be dispersed. Such dispersants stabilize the pigments by whether they are ionizable and by the polarity of the solvent, by steric effects and / or by electrostatic effects.
Agents that inhibit corrosion caused by certain salts, such as chlorides that contribute to electrical conductivity (see European Patent No. 0510752 and US Pat. No. 5,102,458),
Additives that protect the ink from the growth of bacteria and other microorganisms: biocides, bactericides, fungicides, etc., especially for inks containing water.
PH adjustment buffer (see EP 0735120)
・ Defoamer

  Ink for inkjet modifies wettability or ink penetration (US Pat. No. 5,395,431) Surfactant or surface active agent, especially 3M Fluorad FC 430 to modify or adjust static or dynamic surface tension May be included. Such products adjust the magnitude of the droplet impact. Thus, droplet impacts all have the same diameter, regardless of the nature, cleanness, or uniformity of the support.

  In addition, the additive optionally includes one or more conductive salts in the case of ink for deflection continuous inkjet printing.

  Any conductive salt contributes to the conductivity required for electrostatic deflection in the ink. Regarding this problem, reference is made to US Pat. No. 4,465,800. However, it should be noted that in some cases, the dye already contributes well to the conductivity to the ink and there is no need to add a conductive salt.

  Among the salts that contribute to electrical conductivity, any type of ionizable material that can be dissolved and dissociated in the solvent medium of the ink is used.

  For inks where the dominant solvent is water, the conductivity contribution to the ink generally does not present a problem since most water soluble materials are ionizable materials.

  However, the ability of water to solvate is limited and the aqueous medium does not allow various formulations because the evaporation rate of water is very slow to take advantage of the potential of high speed printing enabled by inkjet. In addition, various organic solvents with strong dissolving power for polymers and pigments allow the formulation of inks that dry quickly and adhere very well to all types of substrates.

  In contrast, in these organic media, electrical conductivity is only realized when the solvents are sufficiently dissociated, ie their dielectric constant and dipole moment are sufficiently high. In this case, it is necessary to find salts with cations and anions that are sufficiently soluble in the medium.

  Solvents that can be used in the ink, on the other hand, are acetone, typically to allow a very fast drying of the marking and to adjust the viscosity to the desired value (eg 2 to 10 mPa.s). Or a low-viscosity volatile solvent, such as ethanol, on the other hand, drying more slowly, smaller and more viscous to prevent drying of the ink in the nozzle during the stage when the printing device is shut down Is a high and low volatility solvent.

  Thus, there is a need for a rapidly drying ink that exhibits good start-up quality after a long outage.

  More particularly, commonly used volatile solvents are low molecular weight alcohols, ketones, and esters, as shown, for example, in US Pat. No. 4,567,213 and US Pat. No. 5,637,139. Among these solvents, basically described are methanol, ethanol, 1-propanol, 2-propanol, acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone.

  Less volatile solvents, particularly having a role in retarding drying, are generally ketones such as cyclohexanone, glycol ethers (described in U.S. Pat. No. 4,040,096 and U.S. Pat. No. 4,567,213), For example, ethers and acetals such as furan or dioxane (described in US Pat. No. 4,155,767), dimethylformamide or dimethyl sulfoxide (US Pat. No. 4,155,895), lactones (EP 0034881), N -Methylpyrrolidone (EP 0735120), glycol (WO 96/23844), and aliphatic hydrocarbons (US Pat. No. 4,166,044) or water, alone or the other solvents mentioned above In this regard; U.S. Pat. No. 415 593 Pat, German Pat. No. 2,277,094, and French Patent No. 2,460,982 is referred to.

In general, the main or dominant ink-jet printing ink solvent must meet several criteria, in particular
Their volatility must be sufficient for the ink to dry quickly on the marked support, but not excessively, especially since it does not evaporate too quickly in the printer during the stop phase should not.
• With respect to ink binder, dye or pigment dispersion, and with respect to the printed substrate, their solvating power must be able to give good adhesion on the dry ink.
The dominant or main solvent (and the non-main solvent with low content) is also a dissociated ionization, such as a salt that imparts conductivity to the ink when the ink is a deflection continuous ink jet printing ink. It must have the ability to hold the substance.

  There is also a need to allow rapid marking of all types of items with different surface properties (both porous and non-porous), particularly for inks that are suitable for deflected continuous ink jet printing.

  In addition, the ink must provide markings that exhibit good adhesion and good resistance to chemical action. In particular, it must provide water-resistant markings and generally all properties (viscosity, resistance, etc.) normally required for ink jet printing inks, especially for printer inks using continuous ink jet technology. ) Must be indicated. At the same time, the ink must have the property of being quickly dried and of being capable of rapid start-up even after long stops without clogging the nozzles.

  In addition, the ink should allow high speed marking for all types of items, even somewhat porous items, while providing printing or marking with excellent quality and consistency.

US Pat. No. 4,153,593 US Pat. No. 4,756,758 U.S. Pat. No. 4,880,465 European Patent No. 0289141 US Pat. No. 5,395,432 German Patent No. 2298713 U.S. Pat. No. 4,834,799 German Patent No. 2286402 US Pat. No. 5,594,044 US Pat. No. 5,316,575 International Publication No. 96/23844 International Publication No. 95/29287 European Patent No. 0510752 US Pat. No. 5,102,458 European Patent No. 0735120 US Pat. No. 5,395,431 U.S. Pat. No. 4,465,800 US Pat. No. 4,567,213 US Pat. No. 5,637,139 U.S. Pat. No. 4,040,096 U.S. Pat. No. 4,155,767 U.S. Pat. No. 4,155,895 European Patent No. 0034881 European Patent No. 0735120 US Pat. No. 4,166,044 German No. 2277094 specification French Patent No. 2460982 specification U.S. Pat. No. 4,736,425 US Pat. No. 5,998,502 US Pat. No. 6,905,538 US Pat. No. 5,093,147 International application 97/10307 (European patent application 0850281)

Journal of Imaging Technology, Volume 16, Number 4, pp. 158-161

  Accordingly, it is an object of the present invention to apply prior art inks suitable for ink jet printing, in particular, but not limited to, deflection continuous ink jet printing, especially satisfying the above criteria and requirements, which meet all the above mentioned needs. It is to provide an ink composition that overcomes the problems of the prior art compositions without the disadvantages, limitations, deficiencies and disadvantages of the composition.

  The object of the present invention is particularly colorless, invisible to the naked eye and fluorescent when irradiated with ultraviolet light, or more particularly colorless, invisible to the naked eye and irradiated with ultraviolet light. It is to provide an ink composition for ink jet printing that provides a marking that is fluorescent, said ink composition comprising a rare earth metal complex, and the specific need described above for such a fluorescent ink composition, in particular Satisfying the stability of fluorescence.

This and other objects are achieved according to the present invention by an ink composition that is invisible to the naked eye and is fluorescent, inkjet printing, liquid at ambient temperature, including:
a) an ethanol-soluble binder comprising at least 0.5% by weight of at least one thermoplastic polyamide resin, based on the total weight of the ink;
b) a solvent comprising at least 10% by weight of one or more organic solvent compounds relative to the total weight of the ink;
c) at least 0.05% by weight relative to the total weight of the ink, invisible to the naked eye, fluorescent in the visible region only when exposed to ultraviolet light, selected from rare earth metal chelates and rare earth metal complexes One or more dyes and / or pigments;
d) less than 10% water by weight relative to the total weight of the ink.

  The fluorescent dyes or pigments of the ink compositions according to the present invention are colorless and invisible to the naked eye, i.e. do not show significant absorption in the visible light wavelength range, approximately 400 to approximately 700 nm.

  In addition, these fluorescent dyes or pigments emit fluorescent radiation in the visible region only when exposed to ultraviolet light radiation, typically in the wavelength range of 275 to 400 nm, and only when they are exposed to this radiation. .

  More specifically, it can be said to be a marking or print that is not visible to the naked eye or is produced by the colorless ink composition of the present invention and that is fluorescent under the conditions described herein.

  The fluorescence wavelength of the dye contained in the composition of the present invention is generally about 700 nm or less, preferably about 650 nm or less.

  Preferably, when it is desired to perform printing on a white substrate, the ink composition according to the present invention has a wavelength present above the fluorescent wavelength of the optical brightener, typically 380 to 500 nm. Includes fluorescent dyes in the range.

  Advantageously, the fluorescence wavelength of the dyes and / or pigments of the composition according to the invention is from approximately 550 or 575 nm to approximately 700 nm, more preferably from 600 to 650 nm.

  The above fluorescence wavelength condition is essentially met by itself due to the fact that rare earth metal complexes are included.

  The term “rare earth metal” is understood to mean all elements known as lanthanides, ie elements contained between atomic numbers 57 to 71.

  Preferred elements are samarium, europium, gadolinium, neodymium, terbium, erbium, and dysprosium, and the fluorescent dye and / or pigment is selected from samarium, europium, gadolinium, neodymium, terbium, or dysprosium complexes or chelates, and mixtures thereof Is done.

  Examples of rare earth metal complexes or chelates of the composition according to the invention include organic ligands (acetylacetone, benzoylacetone, dibenzoyl) of rare earth metals or lanthanide ions (neodymium, europium, samarium, dysprosium, gadolinium, erbium, terbium ions, etc.) And those formed by chelation or complexation with methane and salicylic acid.

  Examples of such complexes include europium acetylacetonate, samarium acetylacetonate, neodymium benzoylacetonate, terbium salicylate, and dysprosium benzoylacetonate.

  The complex or chelate may be prepared by any process known to those skilled in the art. For example, a ligand such as acetylacetonate can be reacted with a rare earth metal halide, such as europium trichloride, under suitable conditions to produce a rare earth metal chelate. In this regard, reference is made to US Pat. No. 4,736,425.

  The specific chelates mentioned above absorb ultraviolet radiation and are fluorescent in the visible region.

  Europium acetylacetonate is fluorescent with emission lines in the red region and is particularly suitable for printing on white substrates or substrates with light colors.

  Examples of these rare earth metal chelates or complexes that may be included in the ink composition according to the present invention are commercially available under the trade names Honeywell (formerly Hoechst Celanese, Riedel-de Haen) to Lumilux, more particularly Lumilux C. Are available compounds.

The rare earth metal organic chelate Lumilux C has a melting point of about 130 ° C. to about 160 ° C. and has a bulk density of about 500 kg / m ³ to about 1100 kg / m ³ . Examples of Lumilux C organic pigments include Red CD 316, Red CD 331, Red CD 332, Red CD 335, and Red CD 339, which in an unexcited state are yellowish (this yellowish color is a pure solid product) It should be noted that this coloration is no longer observed as soon as the product is dissolved and diluted) and is fluorescent in the orange-red region when excited by ultraviolet radiation.

  These pigments are soluble in organic solvents.

Red CD 331 is a europium chelate and is provided in the form of a yellowish powder having an emission peak at 612 nm, a melting point ranging from 153 to 155 ° C. and a density of 600 kg / m ³ .

  Red CD 331 is soluble in acetone, ethyl acetate, ethanol, xylene, dichloromethane, dimethylformamide, n-hexane and dibutyl phthalate.

  Red CD 316 is a rare earth metal acetylacetonate.

Red CD 332 is a rare earth metal diketonate having a melting point of 135 to 138 ° C. and a density of 500 kg / m ³ .

Red CD 335 is a europium chelate having a melting point of 133 ° C. and a density of 1030 kg / m ³ .

  The term “ambient temperature” is generally understood to mean a temperature of 5-30 ° C., preferably 10-25 ° C., more preferably 15-24 ° C., even more preferably 20-23 ° C. It is clearly understood that the ink is a liquid at ambient pressure.

  Advantageously, the ink composition according to the invention is from 0.05 to 25% by weight, preferably from 0.1 to 25% by weight, more preferably from 0.2 to 10% by weight, more preferably from the total weight of the ink. 0.5 to 5% by weight of pigments and / or dyes selected from rare earth metal chelates and complexes.

  According to the invention, the binder of the ink composition comprises at least 0.5% by weight of at least one polyamide resin relative to the total weight of the ink.

  The term “polyamide” is also understood to mean copolymers derived therefrom, known as copolyamides.

  Polyamide resins are often defined according to their solubility in solvents. In accordance with the present invention, ethanol resins that are soluble in ethanol are used because they are more easily dissolved and do not require other more harmless solvents such as hydrocarbons.

  The expression “soluble in ethanol” defining a polyamide resin is well known to those skilled in the art and is widely used in the art. The expression “polyamide resin soluble in ethanol” is generally understood to mean that the resin is soluble in ethanol in all proportions.

  An example of a polyamide resin that can be used in the binder of the ink composition according to the present invention is a thermoplastic polyamide available from Cray Valley under the tradename Crayamid.

  "Series 700" Crayamid polyamide is a thermoplastic polyamide soluble in alcohol (ethanol). They have excellent adhesion to various substrates including all types of plastic films.

  Various properties of Crayamid® polyamide are shown below.

  Among the Crayamid® polyamides, the preferred polyamide is “series 700”, especially Crayamid® 791.

  Other polyamides are polyamides (and copolyamides) available from Huntsman or Schering under the name Eurolon®, such as Eurolon® 962, 965, 966, 969, and 975, etc. Is soluble in ethanol.

  Various properties of Eurolon® polyamide are shown below.

  A preferred Eurolon polyamide is Eurolon 975.

  Other polyamides that can be used in the ink composition according to the present invention are described in US Pat. No. 5,998,502.

  Advantageously, the ink composition is from 0.5 to 25%, preferably from 1 to 20%, more preferably from 4 to 20%, even more preferably from 6 to 10% by weight relative to the total weight of the ink. At least one polyamide resin.

  The amount of polyamide resin is adjusted to adjust the viscosity while retaining the effect of fluorescence stability.

  The ink composition according to the present invention is a very specific thermoplastic resin that is further soluble in ethanol, in that it comprises at least one polyamide resin as a binder from the prior art composition. In some respects, it is fundamentally different in that it contains at least one rare earth metal complex or chelate as a dye or pigment and finally contains less than 10% of water.

  There is no prior art document describing inks that exhibit a particular combination of properties of the composition according to the invention.

  In particular, an ink composition comprising simultaneously a specific binder according to the present invention comprising a specific or special thermoplastic polyamide resin soluble in ethanol and a specific dye according to the present invention, wherein said ink is further reduced or zero There is no prior literature describing what contains an amount of water.

  US Pat. No. 6,905,538 describes a highly permeable water-based ink containing a rare earth metal complex type fluorophore dye. The dominant presence of water requires that all ingredients including the “fluorophore” be soluble in water. Such inks cannot be applied to non-porous supports such as plastic packaging.

  In addition, the ink may contain polar solvents, surfactants and humectants, the presence of binders is not described, and polyamide resins are further described for the stronger reason that they are ethanol-soluble thermoplastic polyamide resins. Absent.

  U.S. Pat. No. 5,093,147 relates to an invisible ink that absorbs infrared light because it emits longer wavelength infrared light by fluorescence. These inks contain fluorescent organic dyes but are not rare earth metal complexes or chelates. In the examples, resins of either rosin ester or poly (vinyl alcohol) PVA are used. There is no mention or suggestion of incorporation of a polyamide binder.

  These inks require special equipment to detect because the emission of infrared light is invisible.

  R. of “Journal of Imaging Technology, Volume 16, Number 4, pp. 158-161” published in August 1990. The article by Chanderaskar presents the use of rare earth metal chelates (europium, dysprosium, and terbium) complexed with dibenzoylmethane in combination with ethylcellulose and polyvinyl butyrol binders in the preparation of inkjet inks. There is no mention or suggestion in this document that such chelates can be advantageously combined with polyamide-type resins, in particular with certain thermoplastic polyamide resins soluble in ethanol.

  International application 97/10307 (European patent application 0850281) describes inks based on rare earth metal complex type dyes, for example in combination with a binding resin which may be selected from at least 38 resins or a family of resins thereof. Among these resins, no mention is made of polyamides, especially thermoplastic polyamides soluble in ethanol. Preferred resins are polyurethane, polyvinyl pyrrolidone, and ethyl cellulose for the European patent based on the aforementioned international application.

  There is no description in this document indicating that the ink described herein can contain a polyamide-type resin, particularly a specific thermoplastic polyamide resin of a type soluble in ethanol, and a specific polyamide resin. For the use in the composition of the present invention, the unexpected effects mentioned above are neither mentioned nor mentioned in this document.

  The ink composition according to the present invention fulfills all the above-mentioned needs and meets all the above-mentioned standards and requirements and solves the problems encountered by prior art inks, especially fluorescent inks containing rare earth metal complexes.

  The composition according to the present invention dries quickly due to the presence of the polyamide resin essentially as a binder and at the same time does not cause clogging of the nozzle, provides an immediate set-up and generally uses ink jet technology (deflection continuity). It has been found that it makes it possible to formulate stable ink compositions that meet all the standards, requirements and needs in (numeric inkjet technology, or drop-on-demand technology).

  In addition, surprisingly, polyamide resins can be applied to these inks for extended periods of time (eg, 6 months to 1 year in a pot that remains intact during continuous operation in the printer). Even) has been demonstrated to confer stability on all fluorescent properties.

  Furthermore, this stabilizing effect can be obtained whatever the rare earth metal complex used, and whether the concentration of this complex is low or high, this stabilizing effect is particularly notable for europium acetylacetonate, samarium. Indicated for acetylacetonate, neodymium benzoylacetonate, terbium salicylate, and dysprosium benzoylacetonate, and for Lumilux CD331 and CD316 compounds.

  Such stabilizing effects of polyamide resins on the fluorescence stability of rare earth metal complexes and chelates are not described or suggested in the prior art and are completely surprising.

  This stabilization, such as nitrocellulose, does not bring about the fluorescent stability of rare earth metal complexes, as other binders known for their excellent behavior in terms of handling the ink in the printer and the stability of its drying rate. The effect is not self-evident, it is quite surprising. Similarly, novolac-type phenolic resins, styrene / acrylic resins, acrylic resins, and shellac are all widely used to formulate ink-jet inks, but do not provide fluorescence stability in formulations with rare earth metal chelates.

  The composition of the present invention provides a marking with high quality and consistency whatever the support.

  In other words, there is a real synergy between the rare earth metal complexes or chelates on the one hand and the specific polyamide resins on the other hand the binder of the ink according to the invention, which leads to an unexpected stabilization of the fluorescence for these complexes. On the other hand, it can be said that the ink and the markings prepared from this ink exhibit all the excellent properties required for ink jet printing inks and the markings obtained with them.

  The resulting marking is water resistant.

  This is in contrast to the prior art compositions, where the water content of the ink composition according to the invention is low, generally less than 10% by weight, preferably less than 5% by weight, based on the total weight of the ink, More preferably, it is less than 1% by weight.

  The ink composition according to the invention can even be considered essentially devoid of water and free (0% water).

  In fact, the only water present is water introduced as an impurity in the various components of the ink. As the purity of the selected components increases, the water content decreases.

  The low content or absence of water in the ink composition according to the present invention facilitates the formation of an ink film when the binder and other dyes of the composition are insoluble in water, and thus ink resistance and adhesion. Improve sex.

  In the composition according to the invention, the solvent comprises one or more organic solvent compounds which are generally at least 10% by weight relative to the total weight of the ink. The solvent is preferably 30 to 90% by weight, more preferably 60 to 80% by weight, based on the total weight of the ink.

  The solvent optionally includes water if one or more organic solvent compounds and the above conditions are observed by the amount of water.

  Said organic solvent compounds forming part of the solvent are, for example, alcohols, in particular low molecular weight alcohols such as aliphatic alcohols; ketones, preferably low molecular weights; alkylene glycol ethers; alkylene glycol esters and alkylene glycol ether esters such as acetates. Dimethylformamide; N-methylpyrrolidone; acetal; ester; linear or cyclic ether; cyclic or acyclic, eg linear or branched, aliphatic hydrocarbon; aromatic or non-aromatic hydrocarbon; and carbonate, eg propylene carbonate , Ethylene carbonate, dimethyl carbonate, and diethyl carbonate; and mixtures thereof.

  Preferably, this solvent has the property of dissolving other components of the ink, particularly binders, coloring materials, additives and the like.

  The alcohol preferably has 1 to 8 carbon atoms, such as methanol, modified or unmodified ethanol, propan-1-ol, propan-2-ol, n-butanol, butan-2-ol, tert-butanol and the like. Selected from linear or branched fatty alcohols.

  The ketone is preferably acetone, butanone (methyl ethyl ketone), pentan-2-one (methylpropyl ketone), 3-methylbutan-2-one (methyl isopropyl ketone), and 4-methylpentan-2-one (methyl isobutyl ketone). ), Etc., selected from ketones having 3 to 10 carbon atoms.

  The alkylene glycol ether is preferably selected from monoalkyl (C1 to C6 alkyl groups) or dialkyl (C1 to C6 alkyl groups) ethers of alkylene glycols containing 1 to 10 carbon atoms in the alkylene chain, preferably ethylene Or propylene glycol ether such as methoxypropanol.

  The glycol esters and glycol ether esters are preferably selected from glycol esters and glycol ether esters having a saturated aliphatic carboxylic acid having 1 to 6 carbon atoms, such as formic acid, acetic acid, propionic acid, butyric acid, Herbic acid, caproic acid and the like.

  For example, methoxypropyl acetic acid, butyl diglycol acetic acid and the like.

  The ester is preferably selected from low molecular weight esters, for example formates, acetates, propionates or acetates of alcohols having 1 to 10 carbon atoms.

  The acetal is preferably selected from low molecular weight acetals, such as ethylal and methylal.

  The ether is preferably selected from low molecular weight ethers, for example dioxolane or tetrahydrofuran.

  The ink composition according to the present invention comprises one or more dyes and / or pigments selected from the rare earth metal chelates mentioned above.

  In addition to the one or more polyamide resins described above, the binder of the ink composition according to the present invention is generally selected from resins that are compatible with the polyamide resin, and one or more other binders different from the polyamide resin. Resins and / or polymers may be included.

  In general, the polyamide resin (which is at least 0.5% by weight based on the total weight of the ink composition) is preferably at least 50% by weight, preferably based on the total weight of the binder. At least 75% by weight, and more preferably 100% by weight with respect to the weight of the binder. In other words, the binder is simply composed of a polyamide resin, and an optimum stabilizing effect is obtained.

  The proportion of (total) binder in the ink composition according to the invention is generally from 0.5 to 40% by weight, preferably from 1 to 25% by weight, more preferably from 3 to 20% by weight.

  The ink composition includes, for example, one or more (binder resin or polymer), including one or more polymers and / or resins selected from plasticizers known to those skilled in the art and selected according to the binder used. The plasticizer may further include a plasticizer, and examples of the plasticizer include thermoplastic polyurethane.

  The plasticizer is generally 0.1 to 20% by weight based on the total weight of the ink composition.

  The ink composition according to the present invention is a salt that can introduce conductivity into the ink itself when other materials dissociate if it must be able to be ejected by deflected continuous ink jet. In general, at least one conductive salt is generally included unless a conductive salt need be added as appropriate to provide sufficient conductivity.

  This is because when the ink according to the invention must be able to be applied by deflection continuous ink jet, it is sufficiently conductive in the liquid state (generally greater than 300 μS / cm at 20 ° C., preferably Is greater than 500 μS / cm, for example on the order of 500 to 2000 μS / cm (at 20 ° C.).

  This conductive salt is generally an alkali metal salt, such as lithium, sodium, or potassium, an alkaline earth metal salt, such as magnesium and calcium, and a simple or quaternary ammonium salt; a halide form (chloride, Bromide, iodide, or fluoride), perchlorate, nitrate, thiocyanate, formate, acetate, sulfate, propionate, trifluoroacetate, triflate (trifluoromethanesulfonate), hexa Selected from fluorophosphate, hexafluoroantimonate, tetrafluoroborate, picrate, carboxylate, and sulfonate.

  As a result, these conductive salts are present in the ink composition, if necessary, to provide the above conductivity of the ink. Preferably, their amount is from 0.1 to 20% by weight, more preferably from 0.1 to 10% by weight, and even more preferably from 0.1 to 5% by weight, based on the total weight of the ink composition.

  The composition according to the present invention further comprises one or more additives selected from compounds that improve the solubility, print quality, adhesion or control of the wettability of the ink on different substrates. Good.

  The additive can be selected from, for example, antifoaming agents, chemical stabilizers, UV stabilizers, surfactants, agents that inhibit salt corrosion, bactericides, fungicides, biocides, pH adjustment buffers, and the like.

  Additives are used in very low addition amounts and are generally less than 5% and sometimes on the order of 0.01% depending on whether an antifoam, stabilizer or surfactant is included. .

  Another subject of the present invention is the use of a substrate or support, for example a porous or non-porous substrate or support, of these substrates or of an ink composition as described above by means of ink jet printing technology. It is a step of marking by jetting onto the upper part of the support.

  Marking is performed by deflection continuous inkjet technology or by drop-on-demand technology.

  Another object of the present invention is to provide a substrate, for example a porous or non-porous substrate or support, provided with a marking obtained by drying and / or absorption of the ink composition described above. It is a support.

  The marking essentially comprises the chelating dye or pigment and likewise a binder and is obtained by evaporation and / or absorption of essentially all other components of the ink, such as solvents, into the substrate.

  The substrate can be, for example, a metal such as aluminum or steel (beverage cans), glass (glass bottles), ceramic, optionally coated or glazed cellulosic material (eg paper), cardboard or wood, especially in the form of films. Polymer ("plastic"), such as PVC, PET, or polyolefin, such as polyethylene (PE) or polypropylene (PP), "Plexiglas", cloth, or any other non-porous or porous material, or the aforementioned materials It may be made of a composite material.

  Preferably, the substrate is made of paper, for example white paper, kraft paper or bond paper.

  This substrate is in particular a postal item, such as letters, envelopes, parcels, parcels and stamps; confirmation documents such as certificates and passports, banknotes, checks, stocks, securities, tickets including admission tickets, plastic packaging It may be selected from film, such as for magazines delivered by mail and other newspapers.

  Marking or printing with excellent quality can be obtained on all substrates, even substrates that are very poorly porous and exhibit very uneven surfaces. Similarly, fluorescence stability is obtained even if the substrate is for example porous or non-porous. Fluorescence can be reliably detected for all types of substrates, whether white, light or deeply colored, and regardless of their color.

The invention further relates to a method for identifying an article comprising the following sequential steps.
A safe marking is formed on the item using the ink according to the invention as described above (eg one marking for each item), which is not visible to the naked eye and can only be seen when illuminated by ultraviolet radiation .
• The product is excited by ultraviolet radiation.
By reading the fluorescent radiation emitted by these markings, the markings are read.
The item is identified according to the reading;

  The invention will be better understood by reading the following description of embodiments of the invention, given for illustration and non-limiting examples.

Examples The following ink compositions according to the present invention were prepared by mixing the materials listed in Table I below in the indicated ratios. The viscosity and conductivity of the resulting ink are also given in Table I below.

  The inks of Examples 1-10 were prepared by simple mixing of various ingredients using agitation.

  After filtration through a filter with an absolute porosity of 2 μm, each example 1 to 10 gives ink that can be jetted by Series 8 and Series 9020, 9030, and 9040 type Image printer ink jets, enabling excellent quality printing to be obtained. To do. The marking was formed on a post plastic packaging film made of polyethylene.

  These markings were also compared to markings produced on the same support with the same type of ink for a Videojet printer referring to 165480Q, which contained europium chelates and clearly had the same fluorescence performance.

  Fluorescence stability is the same under 365 nm UV irradiation on the markings produced with each ink, immediately after marking, and on the one hand after 3 weeks without exposure to light and on the other hand after exposing both to sunlight Under conditions, it was evaluated by comparing fluorescence.

  Fluorescence was assessed visually and divided into 0 to 5 stages. Stage 0 means that the fluorescence has been completely lost, and stage 5 means "visually unchanged from the original".

  The fluorescence stability of the marking produced was similarly tested with the best ink after running the printer continuously without printing for 1 and 3 weeks. Under these conditions, the effects of ink recirculation and the effects of contact with ambient air are greatest, corresponding to extreme extremes far beyond those encountered in industrial applications.

  The results of the tests are summarized in Table II below.

  The fluorescence stability according to these various tests is such that only the compositions according to the invention (7, 8, 9, 10) of the present invention containing polyamide type resins, among the tested compositions containing different resins. Any level or type of fluorescent complex can be obtained under such conditions.

Claims (29)

A fluorescent, ink-jet printing ink composition that is invisible to the naked eye, liquid at ambient temperature,
a) an ethanol-soluble binder comprising at least 0.5% by weight of at least one thermoplastic polyamide resin, based on the total weight of the ink;
b) a solvent comprising at least 10% by weight of one or more organic solvent compounds relative to the total weight of the ink;
c) at least 0.05% by weight relative to the total weight of the ink, invisible to the naked eye, fluorescent in the visible region only when exposed to ultraviolet light, selected from rare earth metal chelates and rare earth metal complexes One or more dyes and / or pigments;
Including
Optionally including more than 0% and less than 10% water by weight relative to the total weight of the ink;
The complex or chelate is selected from europium acetylacetonate, samarium acetylacetonate, neodymium benzoylacetonate, terbium salicylate, and dysprosium benzoylacetonate ;
The polyamide resin is Ru 100 wt% der relative to the total weight of the binder, the ink composition.   The composition of claim 1, wherein the fluorescent dye and / or pigment emits fluorescent radiation in the visible region when exposed to ultraviolet light radiation having a wavelength range of 275 to 400 nm.   The composition according to claim 1, wherein the fluorescent dye and / or pigment emits fluorescent radiation having a wavelength of 700 nm or less.   The composition according to claim 3, wherein the fluorescent dye and / or pigment emits fluorescent radiation having a wavelength of 550 or 575 nm to 700 nm. Relative to the total weight of the ink, is selected from 0.05 to 25% by weight of rare earth metal chelate and complexes, including pigment and / or dye composition according to any one of claims 1 to 4. Relative to the total weight of the ink, the 0.5 to 25 wt% including at least one polyamide resin composition according to any one of claims 1 to 5. The ink composition according to any one of claims 1 to 6 , comprising 0.5 to 40% by weight of the binder. The composition according to any one of claims 1 to 7 , comprising water in an amount of more than 0% and less than 5% by weight relative to the total weight of the ink. The composition according to any one of claims 1 to 8 , wherein the solvent is 30 to 90% by weight with respect to the total weight of the ink composition. 10. A composition according to any one of claims 1 to 9 , wherein the solvent comprises one or more organic solvent compounds and optionally water. The organic solvent compound includes alcohol, ketone, alkylene glycol ether, alkylene glycol ester and alkylene glycol ether ester, dimethylformamide, N-methylpyrrolidone, ether, acetal, ester, cyclic or acyclic aliphatic hydrocarbon, aromatic or non-aromatic hydrocarbon; and carbonates; and mixtures thereof, the ink composition according to claim 1 0. The organic solvent compounds, acetate, propylene carbonate, ethylene carbonate, dimethyl carbonate, and diethyl carbonate, and mixtures thereof, the ink composition according to claim 1 1. The organic solvent compound comprises a linear or branched aliphatic alcohol having 1 to 8 carbon atoms; a ketone having 3 to 10 carbon atoms; a monoalkyl of alkylene glycol containing 1 to 10 carbon atoms in the alkylene chain ( A C1 to C6 alkyl group) or a dialkyl (C1 to C6 alkyl group) ether; or an ester of an alkylene glycol having a saturated aliphatic carboxylic acid having 1 to 6 carbon atoms and an ester of an alkylene glycol ether. a composition according to claim 1 1. The organic solvent compound is selected from ethylene glycol and propylene glycol, composition according to claim 1 3. The solvent modified or unmodified ethanol, ketones having 10 carbon atoms 3, and an organic solvent a compound selected from mixtures thereof A composition according to claim 1 3. Further comprising one or more plasticizers in a proportion of 0.1 to 20% by weight, the ink composition according to any one of claims 1 1 5. The composition according to any one of claims 1 to 16 , further comprising at least one conductive salt. 18. The composition of claim 17 , wherein the conductive salt is 0.1 to 20% by weight relative to the total weight of the ink composition. The conductive salts include alkali metal salts, alkaline earth metal salts, and simple or quaternary ammonium salts, halide forms, perchlorates, nitrates, thiocyanates, formates, acetates, sulfates, propions salt, trifluoroacetic acid salt, triflate, hexafluorophosphate, hexafluoroantimonate, tetrafluoroborate, picrate, is selected from carboxylates, and sulfonates, in claim 18 The ink composition as described. The ink composition according to any one of claims 1 to 19 , which has a conductivity of greater than 300 µS / cm and less than or equal to 2000 µS / cm at 20 ° C. One or more additives selected from anti-foaming agents, chemical stabilizers, UV stabilizers, surfactants, agents that inhibit corrosion by salts, bactericides, fungicides, biocides, pH adjusting buffers including the ink composition according to any one of claims 1 2 0. The ink composition according to any one of claims 1 to 21, wherein the ink composition is a method of marking a substrate by ejecting the ink composition onto a substrate by an inkjet printing technique. The way that is. The inkjet printing technique is deflected continuous inkjet technology or drop-on-demand technology, the marking method according to claim 2 2. A base material provided with a marking obtained by drying and / or absorption of the ink composition according to any one of claims 1 to 21. The substrate may be a metal, glass, ceramic, cellulose-containing material, synthetic polymer (“plastic”), “plexiglass”, cloth, or any other non-porous or porous material, or two or more of the aforementioned materials characterized in that it made of a composite material substrate according to claim 2 4. The substrate is aluminum, steel, optionally coated or polished paper, originally white paper, kraft paper, bond paper, cardboard, wood, PVC, PET, polyolefin, polyethylene (PE), polypropylene (PP), The substrate according to claim 25 , wherein the substrate is made of a composite material of two or more of the aforementioned materials. 26. A substrate according to claim 25 , selected from postal items; confirmation documents; banknotes; checks; stocks; securities; tickets including admission tickets; 28. A substrate according to claim 27 , selected from letters, envelopes, parcels, parcels, stamps. A method of identifying an item that includes the following sequential steps:
A safe marking is formed on an article using the ink according to any one of claims 1 to 21 and the marking is not visible to the naked eye and can only be seen when illuminated by ultraviolet radiation. ,
・ The item is excited by ultraviolet radiation,
By detecting the fluorescent radiation emitted by these markings, the markings are read,
The item is identified according to the reading;