FR2862657A1 - Ink for continuous, diverted ink-jet printing, useful particularly for franking postage, comprises binder, dye, pigment and a solvent consisting mainly of propylene carbonate - Google Patents

Abstract

Ink (A) for continuous diverted ink-jet printing, liquid at ambient temperature, comprises a binder (I); at least one dye and/or pigment (II) and a solvent (III), where (III) comprises over 70 wt.%, on total composition, of propyl carbonate (IIIa) and less than 10 % water, especially no water. An independent claim is also included for a substrate having a marking produced by drying (A).

Description

INK COMPOSITION FOR JET PRINTING

CONTINUOUS DEVICE

  NOTABLY ON LETTERS AND POSTAL OBJECTS

DESCRIPTION

  The invention relates to an ink composition for marking media and objects of all kinds whose properties are particularly well suited to marking or printing by liquid jet and especially to continuous ink jet marking. deviated from a very wide variety of supports, both porous and non-porous.

  This ink composition is particularly suitable for marking or obliteration of letters and postal objects, including the marking, obliteration, stamps.

  Inkjet printing is a well-known technique, which allows the printing, marking, or decoration of all kinds of objects, at high speed, and without contact of these objects with the device. printing, variable messages at will, such as barcodes, deadlines, etc. even on non-planar supports.

  Inkjet printing systems are divided into two main types: drop on demand (DOD) or continuous jet (CJ).

  We will focus more particularly on this last technique, more precisely on the deviated continuous jet technique.

  The deflected continuous jet projection consists in sending ink under pressure into a cavity containing a piezoelectric crystal, from which the ink escapes through an orifice (nozzle) in the form of a jet. The piezoelectric crystal, vibrating at a specific frequency, causes pressure disturbances in the ink jet, which oscillates and breaks down into spherical droplets. An electrode, placed in the path of the jet, where it breaks, makes it possible to give these drops an electrostatic charge, if the ink is conductive. The drops thus loaded are deflected in an electric field and allow printing.

  This type of jet ink projection ensures high speed non-contact marking of scrolling on non-planar objects and with the possibility of changing messages at will.

  The ink compositions, suitable for deviated continuous jet projection, must satisfy a certain number of criteria inherent in this technique, relating, inter alia, to the viscosity, the electrical conductivity, the solubility in a solvent for cleaning, the compatibility of ingredients, proper wetting of media to be marked, etc. In addition, these inks must dry quickly, be able to pass through the nozzle without clogging, with a great stability of orientation of the jet while allowing easy cleaning of the print head.

  The ingredients that make up the current inks, for the deviated continuous jet type ink jet, are organic or inorganic products, dyestuffs, such as dyes or pigments, resins or binders, in one or more solvents. more or less volatile (s) or in water, optionally one or more salt (s) conductivity, and various additives.

  The salt (s) of possible conductivity (s) provide (s) to the ink the conductivity necessary for the electrostatic deflection. In this regard, reference may be made to US-A-4,465,800.

  Additives include surfactants that modify the wetting or penetrating power of the ink (US Pat. No. 5,395,431), especially those that modify or regulate static or dynamic surface tension, such as Fluorad FC 430 from the 3M Company. , the agents which inhibit the corrosion induced by the salts mentioned above (see EP-A-0 510 752, US-A-5,102,458), or the additives which protect the ink against the proliferation of bacteria and other microorganisms: these are biocides, bactericides, fungicides and others, particularly useful in water-containing inks, pH-regulating buffers (see EP-AO 735 120), antifoaming agents.

  The dyestuffs are called l; dyes or pigments, depending on whether they are respectively soluble or insoluble in the solvent used.

  Pigments, by nature insoluble, are therefore dispersed and may be opaque or not. They bring to the ink its color, its opacity, or particular optical properties, such as fluorescence (see US Pat. Nos. 4,153,593, US-A-4,756,758, US Pat. 4,880,465, EP-A-0 289 141, US-A-5,395,432, GB-A-2,298,713). In some cases, the dyes also provide enough ink conductivity that there is no need to add a conductivity salt. The dyes known under the name C. I. Solvent Black 27, 29, 35 and 45 are in this case.

  The binder (s) or resin (s) is (are) generally for the most part solid (s) and polymeric compound (s) and their choice is dictated by their solubility in the selected solvents and by their compatibility with dyes and other additives, but also and especially according to the properties they bring to the ink film, once dry (see patents or patent applications US-A-4,834,799, GB-A -2,286,402, US-A-5,594,044, US-A-5,316,575, WO-A-96/23844, WO-A-95/29287).

  Their primary function is to provide the ink with adhesion on the maximum of supports or on specific supports, for example non-porous. They also make it possible to give the ink the appropriate viscosity for the formation of the drops from the jet and they bring to the ink, or rather to the marking obtained, most of its properties of resistance to physical and / or chemical attack. .

  The solvent of these inks consists most frequently of a mixture comprising, on the one hand, a major amount of volatile and low-viscosity solvents, in order to allow the labels to be dried very quickly and to adjust the viscosity to the desired value. for example from 2 to 10 mPa.s and, on the other hand, more viscous and less volatile solvents with slower drying, in a lesser amount, to avoid drying the ink in the nozzle during the phases of stopping the printing apparatus (see US Pat. Nos. 4,155,767, WO-A-92,14794, WO-A-92,147,55 and US-A-4,260,531).

  The volatile solvents used most often are alcohols, ketones or low molecular weight esters, as indicated in US-A-4,567,213 and US-A-5,637,139. mention mainly methanol, ethanol, 1- and 2-propanol, acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, ethyl acetate, and tetrahydrofuran.

  US-A-4,210,566 discloses an ink predominantly based on n-propyl acetate.

  Tetrahydrofuran is cited in US-A-4,155,767 as the essential component of the ink-jet ink solvent (40-85%).

  US-A-4 166 044 discloses an ink without a binder, wherein the solvent comprises water (10 to 35%), an alcohol (6 to 25%) and an organic compound selected, for example, general, among cyclic ethers. This ink has all the disadvantages associated with the presence of water.

  Finally, JP-A-63 06316 discloses an inkjet ink composition whose solvent is water mixed with another solvent, selected from 14 other compounds including 1,3-dioxolane.

  The less volatile solvents having in particular a function of drying retarder are most often ketones, such as cyclohexanone, glycol ethers, cited in US-A-4,024,096 and US-A-4,567,213; acetals, such as tetrahydrofuran or dioxane, mentioned in US-A-4 155 767, dimethylformamide or dimethylsulfoxide (US-A-4 155 895), lactones (EP-A-0 034 881), N-methylpyrrolidone (EP-A-0 735 120), glycols (WO-A-96 23 844), and even aliphatic hydrocarbons additionally having an oil film penetrating function (US-A-4 166 044), or water, alone or in combination with other solvents, mentioned above, reference should in this connection be made to US-A-4 153 593, GB-A-2 277 094 and US Pat. FR-A-2,460,982.

  In general, the main or major solvents of the inks for deviated continuous jet projection must meet a certain number of criteria, in particular: their volatility must be sufficient for the ink to dry rapidly on the support to be marked, but not too big, so as not to evaporate too quickly in the printer; their solvent capacity, with respect to the binders of the ink, the dyes or pigment dispersions and with respect to the supports to be printed, must make it possible to impart to the ink a good adhesion; - they must have the ability to maintain dissociated ionic species (salts) that give the ink its electrical conductivity; - their effect on the health of persons, namely their toxicity, harmfulness, irritancy and flammability, must be reduced; they must make it possible to maintain sterile an ink possibly intended to be ingested.

  None of the solvents, said major or majority, currently commonly used in inks for continuous jet printing, simultaneously meets all the criteria mentioned above.

  Thus, methanol is toxic and has poor solvent power; ethanol is not sufficiently volatile and its solvent power is not important enough; ethyl acetate and other acetates have an extremely strong odor, which is an unacceptable defect in many applications; acetone is too volatile with a very low flash point (18 C); methyl-ethyl-ketone (MEK) has adequate solubility and good solvent power, but it is irritating, odorous and highly flammable with a flash point of -9 C, moreover, it is even proscribed by regulations some countries; tetrahydrofuran (THF) has a greater volatility than methyl ethyl ketone, since its boiling point is 10 C lower than that of methyl ethyl ketone, its flash point of -17 C is almost As low as that of acetone, it can form explosive peroxides, it is irritating like methyl ethyl ketone and inks containing more than 25 must be labeled as irritants.

  Because of their flammability, most of the solvents mentioned above (methanol, ethanol, methyl ethyl ketone, ethyl acetate, acetone) are rated> 2 (rated> 2) for all the criteria of the reference standard. NFPA (National Fire Protection Association) in the United States.

  There is therefore an unmet need for an ink composition that is suitable, in particular, for deviated continuous jet printing, in particular on letters and other postal objects whose solvent simultaneously fulfills, among other things, all the mentioned criteria. above, as a result of which, are provided in ink the desired properties, while are met, the requirements, in particular, regulatory in terms of toxicity, flammability and environmental protection.

  It would be interesting to have a solvent that dissolves dyes and other ingredients that can give the ink including its indelibility on substrates and in particular on the stamps.

  There is still a need for an ink particularly suitable for continuous deviated inkjet printing which allows rapid marking of all types of objects with different surface characteristics, both porous and non-porous.

  The ink must, in addition, give a marking which exhibits good adhesion and good resistance to chemical attack and, in general, exhibit all the properties normally required of ink for inkjet printers, in particular for printers using the continuous jet technique: viscosity, resistivity, etc. The ink must, moreover, allow marking at high speed, even low porous objects always giving an impression of excellent quality.

  Finally, the ink must have the required properties (in particular by the postal administrations of different countries) as to the indelibility of the impressions obtained with the ink for example on postal objects, letters and stamps.

  The object of the invention is therefore to provide an ink composition that is particularly suitable for continuous deviated jet printing, which meets, among other things, all the needs indicated above, which satisfies the criteria and requirements mentioned above, and which does not have the drawbacks, limitations, defects and disadvantages of the prior art ink compositions, and which overcomes the problems of the compositions of the prior art related, in particular, to the nature solvent they contain.

  This and other objects are achieved, according to the invention, by an ink composition for deviated continuous jet printing, liquid at room temperature, comprising: - a binder; one or more dyes and / or pigment (s); and - a solvent; wherein said solvent comprises more than 70% by weight - based on the total weight of the ink - of propylene carbonate, and less than 10% by weight of water.

  By ambient temperature is generally meant a temperature of 5 to 30 C, preferably 10 to 25 C, more preferably 15 to 24 C, more preferably 20 to 23 C. It is understood that the ink is liquid to the atmospheric pressure.

  Propylene carbonate has the CAS number [108-32-7], and its structural formula is as follows.

  The still further according to the invention is a specific ink for deviated continuous jet printing, which CH3 basically contains a specific solvent in specific proportions, contains little or no water, and is liquid at room temperature.

  No prior art document describes an ink having all of these specific characteristics.

  The invention is based on the surprising finding that propylene carbonate allows the formulation of an ink, particularly suitable for deviated continuous jet projection and that this is possible without adding water to the formulation or other solvent which would significantly increase the ion dissociation required for conductivity.

  In the prior art, water is generally added to assist in the dissociation of salts; according to the invention, and surprisingly, the ink composition does not contain or little water and yet has sufficient conductivity due to the dissociation action of propylene carbonate.

  It has been demonstrated, according to the invention, in particular, that, in a completely surprising way, propylene carbonate is a solvent whose solvent and penetrating power is such that it allows the formulation of an ink composition. particularly suitable for the obliteration of letters and postal objects, which is conductive, therefore projectable by continuous jet, and this although it contains little or no water.

  In spite of its low volatility and its very low drying rate, propylene carbonate, quite surprisingly, makes it possible, with the ink composition according to the invention, to print high-speed objects even with a low porosity, thanks to its high penetration capacity, especially substrates including cellulose, such as paper or cardboard which make up letters, postal items and stamps.

  It is very surprising that a solvent as volatile as propylene carbonate ensures a high printing speed, even if one would expect the reverse; this rapidity of printing is enabled by the large penetration capacity of the propylene carbonate and therefore of the ink containing it in the substrates.

  It was not obvious from the known compositions that the choice of propylene carbonate (moreover in specific proportions) among the multiplicity of existing organic solvents - could lead to an ink meeting all the criteria, requirements and needs mentioned above, especially in relation to the nature of the solvent.

  On the contrary, there existed in this field of the art - which is that of inks for inkjet printing - a strong, widespread prejudice against the use of propylene carbonate as a solvent. this one is very little volatile, but very polar.

  The invention therefore triumphs over a widespread prejudice in this field of the art by using propylene carbonate, moreover in very high proportions, as a solvent in inks for inkjet printing.

  Propylene carbonate is only mentioned as having a plasticizing action (US-A-6,558,779 and US-A-6,460,957) or as a co-solvent (US-A-6,555,168, US-A-6,533,408) or as electrolyte (US-A-6,501,587), as a penetrant (US-A-6,568,795, US-A-6,554,418, US-A-6,534,566, US-A-6,527,844, US-A No. 6,527,387) or else as a coalescence promoter for systems based on dispersed polymers (latex) (US-A-6,559,245).

  The use of propylene carbonate, in the specific proportions according to the invention, in ink compositions similar to those of the invention with a low water content, in particular for deviated continuous jet printing, is therefore not suitable. neither described nor suggested in the prior art. Indeed, most patents or patent applications of the prior art mention the use of propylene carbonate in addition to water-based inks.

So.

  US-A-4,281,329 relates to a recording liquid medium which is intended for use exclusively in drop-on-demand drop-on-demand devices. It is never mentioned or suggested in this document that the medium can be used in other devices and particularly in deviated continuous jet printing devices.

  This medium contains as essential component an ester of carbonic acid of general formula (A) or (B).

  These formulas and in particular the formula (B) describing the cyclic esters of carbonic acid cover a considerable number of compounds. Columns 5 to 8 cite 48 examples of particular compounds. J i

  Propylene carbonate is used in the examples, but always in combination with large amounts of water and in drop-on-demand type devices. The critical specific proportion greater than 70% according to the invention is not mentioned.

  This document does not contain any incentive to use the compounds of formula (B) and even less, among all of them, propylene carbonate in an ink without water and in a specific ink for deviated continuous jet printing.

  There is no indication in this document, on the unexpected properties of propylene carbonate demonstrated by the inventors in connection with its high penetration ability, which make it particularly suitable for use in an ink for printing by continuous stream deviated.

   . In other words, US-A-4,281,329 claims ink compositions containing up to 99.5% propylene carbonate and a dye, but no binder, but can not explain which component. allows to obtain the conductivity required for continuous jet projection. On the other hand, the inks of the examples all contain significant amounts of water and none demonstrate its ability to be projected by continuous jet, but only by jet drop on demand, - US-B1-6 432 184 relates to an ink composition which comprises a dye, a carrier which may be propylene carbonate and necessarily a light stabilizer, a so-called anti-curl compound, and a poly (dialkyl ammonium dialkyl) chloride. This ink composition is mainly used in acoustic inkjet printing devices. No specific example using an ink with propylene carbonate is given and it is not mentioned that the inks can be used in continuous ink jet printing apparatus.

  No proportion of propylene carbonate in relation to the properties is otherwise indicated.

  In fact, the presence in these inks of the above mandatory components and especially poly (dialkyl ammonium chloride dialkyl) make them totally unsuited to their implementation in the IO continuous jet printers.

  In other words, US-A-6,432,184 claims an ink containing propylene carbonate with a light stabilizer and an anti-curl component, and a di-alkyl di-allyl halide which is likely to render the ink is particularly corrosive to ferrous metals and therefore unusable in industrial jet printers. This patent does not disclose any exemplary embodiment comprising propylene carbonate. US Pat. No. 4,144,040 discloses an azo dye and ink for inkjet printing containing said dye.

  Among a very large number of solvents, propylene carbonate is cited, but no example of ink implementing it is cited.

  Furthermore, this document does not indicate that these inks can generally be used in the deviated continuous jet technique, and still less that an ink containing propylene carbonate has the unexpected advantages according to the invention and is particularly advantageous. adapted to the deviated continuous jet technique. Finally, no necessary specific proportion of propylene carbonate is mentioned.

  In other words, US-A-6,444,020 discloses an ink jet ink where the propylene carbonate can be used alone to dissolve a specific dye, but it does not describe whether or how this formulation could be projected by the deviated continuous jet technique. Nor does it describe how the composition can be made sufficiently conductive. There is no example to support the use of propylene carbonate.

  US-A-6,086,661 relates to an aqueous ink jet ink composition which comprises a quaternary ammonium compound, a liquid carrier, a light stabilizing compound, a antioxidant stabilizer to light, a T.5 salt, a biocide and a dye.

  The carrier is present in an amount of 5 to 70% by weight and may be especially propylene carbonate. However, this document neither describes nor suggests the surprising advantages and benefits obtained according to the invention with propylene carbonate in the context of an ink for continuous jet printing; it does not further indicate that these advantages can be obtained for a specific proportion of propylene carbonate greater than 70% by weight.

  In addition, the compositions of this document contain neither resin nor polymer.

  In other words, US-A-6,086,661 discloses an ink with up to 70% of a carrier which can be propylene carbonate with an organic or inorganic salt, a dye, an anti-curl, a light stabilizer, a biocide and a single quaternary of imidazolium, phosphonium or ammonium. This composition contains neither resin nor polymer.

  US-A-5,593,486 and US-A-5,122,187 disclose hot melt ink compositions (hot melt) so solid at room temperature can use propylene carbonate as a propellant (propellant). Solid inks are therefore unusable in continuous jet at room temperature.

  In contrast to the compositions of the prior art, the ink composition according to the invention contains a very small amount of water less than 10% by weight, preferably less than 5%, more preferably less than 1% by weight. weight relative to the total weight of the ink.

  The ink composition according to the invention can even be considered as essentially free from water (0% water).

  In fact, the water present is only the water supplied as an impurity in the various components of the ink. The higher the purity of the chosen components, the lower the water content.

  The low content or absence of water in the ink composition according to the invention favors high speed printing for which a very high evaporation rate is required.

  The criteria and requirements defined for the properties of a solvent for an ink composition for continuous jet spraying are filled with propylene carbonate, thus: - its boiling point is 230 ° C., and its flash point is 123 C, it is therefore not classified in flammable products within the meaning of 1.7 transport legislation, it should be noted that the flash point of the entire composition is generally greater than 60 C; its volatility is 0.01 (that of butyl acetate being equal to 1), which is very low.

  Its ability to dissolve most polymers is relatively low because of its very high polarity. Its ability to dissolve polymers. is not as general as other more volatile solvents such as methyl ethyl ketone. However, it completely dissolves polymers such as ketone, phenolic and cellulosic resins, among others.

  It is also surprising that despite the low solvent power of polymers, propylene carbonate however allows the formulation of inks for inkjet ensuring indelible prints and high quality.

  The propylene carbonate thus dissolves a large number of resins or polymers serving as an ink binder and ensuring adhesion to the media to be marked.

  Its ability to dissolve dyes, especially C. dyes, is excellent.

  Propylene carbonate is a non-flammable product that is not harmful and is not irritating.

  Propylene carbonate is also ranked <2 for all NFPA (National Fire Protection Association) standards in the United States. The smell of propylene carbonate is also extremely weak, hardly noticeable and not unpleasant.

  According to a fundamental aspect of the invention, the inks according to the invention give markings, impressions, obliterations, indelible according to the most stringent standards of the postal services of different countries. The use of propylene carbonate-containing ink for these purposes is neither mentioned nor suggested in the prior art.

  Propylene carbonate is used to formulate inks whose continuous deviated inkjet printing operation does not require the addition of a fluid (composed of the volatile fraction of the ink) to maintain the viscosity and the constant composition . This type of fluid is commonly called make-up ink or additive, or addition solvent by the skilled person.

  Propylene carbonate is therefore superior to the main solvents, most often used until now in ink compositions for continuous jet projection.

  Propylene carbonate is indeed more interesting than: - methanol which is toxic; - ethanol, which is more volatile and more flammable; ethyl acetate, or other acetates, whose odor is very strong; acetone which is too volatile with a very low flash point (-18 C); methyl-ethyl-ketone, which is irritating, has a much lower flash point (-9 C).

  In addition, all the solvents listed above are, because of their flammability rated> 2 for the NFPA reference criteria.

  The ink composition according to the invention is further characterized by a specific proportion of propylene carbonate, greater than 70% by weight of the total weight of the ink.

  It has been demonstrated that this proportion is critical for the ink composition according to the invention to have all the effects and advantages described herein, in particular in relation to the quality of the marking and its indelibility.

  The composition according to the invention thus comprises more than 70% by weight of propylene carbonate, preferably more than 80%, more preferably more than 85%, better still more than 90% by weight of propylene carbonate.

  In addition, the composition generally contains at most 97%, preferably at most 95% by weight of propylene carbonate.

  A preferred range of the propylene carbonate content will therefore be, for example, 90 to 95% by weight.

  Preferably, the composition according to the invention generally comprises up to 20% by weight, preferably from 5 to 15% by weight of one or more other organic solvent (s) different from the propylene carbonate.

  The other solvent (s) organic (s) forming part of the solvent and other (s) that the propylene carbonate is (are) chosen (s), for example, among alcohols, in particular, alcohols J: low molecular weight, for example, aliphatic alcohols; ketones; alkylen glycol ethers and esters thereof, such as acetates; dimethylformamide; N-methyl pyrrolidone; and carbonates other than propylene carbonate, such as ethylene carbonate and dimethyl and diethyl carbonates; and their mixtures.

  Generally, the amount of the other organic solvent (s) other than propylene carbonate is chosen so that the flash point of the entire composition remains greater than 60 ° C. .

  Preferably, the one or more other organic compound (s) forming part of the solvent is (are) organic solvents whose volatility is greater than that of propylene carbonate.

  Preferably, this or these other solvents have, in addition, the property of dissolving the other ingredients of the ink, in particular the binder, the dyestuffs, the additives, etc. The alcohols will preferably be , chosen from linear or branched aliphatic alcohols of 1 to 5 carbon atoms, such as methanol, ethanol, propanol-1, propanol-2, n-butanol, 2 (butanol-2, tert-butanol, -butanol, etc. The ketones will preferably be chosen from ketones of 3 to 10 carbon atoms, such as acetone, butanone (methyl ethyl ketone) and pentanone-2 (methyl propyl ketone). ), and 4-methyl-2-pentanone (methyl isobutyl ketone).

  The alkylene glycol ethers are chosen from monoalkyl (C1-C6) or dialkyl (C1-C6) ethers of alkylene glycol comprising 1 to 10 carbon atoms in the alkylene chain, preferably it is ethers of ethylene or propylene glycol, such as methoxy-propanol.

  The glycol ether esters are preferably chosen from esters of these with saturated aliphatic carboxylic acids of 1 to 6 carbon atoms, such as formic acid, acetic acid, acid and the like. propionic acid, butyric acid, valeric acid and caproic acid.

  There may be mentioned, for example, methoxypropyl acetate, butyldiglycol acetate, etc.

  The ink composition according to the invention also comprises a binder comprising one or more polymer (s) and / or resin (s). These polymers and / or resins are preferably chosen from (meth) acrylic, vinylic, ketonic, phenolic, cellulosic, styrenic, epoxy resins, polyurethanes, styrene-acrylates and combinations of two or more of these .

  Examples of these resins are as follows.

  For acrylic, methacrylic and styrene-acrylate resins, Joncryl from JOHNSON POLYMER, Acryloid from ROHM & G HAAS, ADM from ATOCHEM or Neocryl from ZENECA.

  For vinyl resins, VIANOVA Hostaflex, UNION CARBIDE Vinylite or WACKER Vinnol.

  For ketone resins, the products offered by the HULS and BASF Companies, such as the so-called AP and SK resins from HULS and the LAROPAL resins from BASF.

  For phenolic resins, the products offered by VIANOVA under the name ALNOVOL.

  Among the cellulosic resins, such as nitrocellulose, ethylcellulose, aceto propionates or cellulose acetate butyrate, mention may be made, for example, of the products offered by the Aqualon or Eastman companies.

  Among the epoxy resins, mention may be made of Epikote offered by Shell or Araldite of CIBA.

  Among the polyurethanes, there may be mentioned Surkopak MITCHANOL Company.

  The proportion of binder in the ink composition according to the invention is generally from 0.1 to 30% by weight, preferably from 1 to 25% by weight, more preferably from 3 to 20% by weight.

  The ink composition may further comprise one or more plasticizers (of the resin (s) or polymer (s) of the binder) chosen, for example, from the known plasticizers of the present invention. Those skilled in the art and chosen according to the binder used comprising one or more polymer (s) and / or resin (s), may be mentioned, as a plasticizer, for example, thermoplastic polyurethanes.

  The solvent power of propylene carbonate makes it easy to incorporate such plasticizer compounds into the composition of the invention.

  The solvent power of propylene carbonate makes it easy to incorporate such plasticizer compounds into the composition of the invention.

  The plasticizer (s) is (are) generally present in a proportion of 0.1 to 20% by weight.

  The dye (s) and / or pigment (s) may be chosen from all the dyes or pigments that are suitable for the intended use, known from

S

  those skilled in the art, some of these pigments or dyes have already been mentioned above.

  They will generally be chosen from the dyes and pigments known under the name of C. I. Solvent Dyes and C. I. Pigments.

  By way of example, the most common pigments and dyes include Solvent Black 29 CI, Solvent Black 7 CI, Solvent Black 28 CI, Solvent Black 35 CI, Solvent Blue 70 CI, Solvent CI Red 124, dispersions Pigment Blue 60 or Pigment Blue 15.

  The total amount of dye (s) and / or pigment (s) is generally from 0.05 to 25% by weight, preferably from 1 to 20%, more preferably from 3 to 10% of the composition.

  Thanks to the ability of propylene carbonate to dissolve the colorant (s) and in particular the most water-resistant dyes, in a larger quantity than the usual solvents, it is particularly possible, in the case of a fluorescent dye, to obtain particularly fluorescent inks, that is to say, visible under low UV illumination.

  The composition according to the invention may, in addition, optionally comprise at least one conductivity salt.

  Indeed, the ink according to the invention being applicable by continuous jet, it must have a sufficient electrical conductivity generally greater than 300 pS / cm at 20 C, preferably of the order of 500 to 2000 pS / cm ( at 20 C), or more.

  Propylene carbonate, relative to other solvents, promotes conductivity, helping to dissociate the ions contained in the ink and therefore the amounts of conductivity salts (see below) can be reduced.

  The products supplying the ink with the conductivity necessary for continuous jet projection are ionizable compounds, such as salts, it is possible that the dyestuffs, already present in the ink, give sufficient conductivity to the ink so that there is no need to add a conductivity salt itself: this is the case of the compounds known under the name CI Solvent Black 27, 29, 35 and 45, already mentioned.

  However, it will often be necessary to include in the ink composition a salt of different conductivity of the dyes and which is generally selected from alkaline, alkaline earth metal and single or quaternary ammonium salts, form of halides (chlorides, bromides, iodides, fluorides), perchlorates, nitrates, thiocyanates, formates, acetates, sulfates, propionates, hexafluorophosphates, hexafluoroantimonates etc. These conductivity salts will therefore be present, if necessary, in the ink composition so as to impart to the ink the above conductivity: preferably, their amount is from 0.1 to 20% by weight, preferably still 0.1 to 10% by weight and more preferably 0.1 to 5% by weight.

  The composition according to the invention may, in addition, comprise one or more additives chosen from compounds which improve the solubility of some of these components, the print quality, the adhesion, or the control of the wetting of the ink. on different media.

  The additive (s) may be chosen, for example, from antifoaming agents, chemical stabilizers, UV stabilizers; surfactants, such as Fluorad FC 430, salt corrosion stabilizers, bactericides, fungicides and biocides, pH buffers, etc. The additive (s) is (are) used at very low doses, generally less than or equal to 5% and sometimes as low as 0.01%, depending on whether it is antifoam stabilizers or surfactants.

  The invention also relates to a method of marking objects, for example, porous or non-porous, by projection onto objects of an ink composition, as described above. The marking is carried out by the deviated continuous jet technique.

  The invention further relates to a substrate or support, for example, porous or non-porous, provided with a marking obtained by drying the ink composition, as described above.

  This substrate may be metal, for example, aluminum, steel (beverage cans), glass (glass bottles), ceramic, a material containing cellulose such as paper, cardboard or wood, synthetic polymer (plastic), such as PVC, PET, polyolefin, such as polyethylene (PE), polypropylene (PP), Plexiglas, or any other non-porous or porous substance or composite of several of the above materials.

  A preferred application according to the invention is the marking, the printing, the obliteration of postal objects, letters, parcels, the substrate is then a substrate containing cellulose, preferably a substrate predominantly or wholly of cellulose. such as paper (possibly coated, glossy or other) or cardboard. The substrate on which the obliteration is made, the printing is for example a postage stamp or other vignette (more exactly the surface of the latter which remains free, exposed when it has been glued for example on a postal object, a package, a letter).

  We obtain markings, impressions of excellent quality on all substrates, even very little porous.

  In the preferred application according to the invention, an excellent quality of printing, marking, obliteration of the postal item, the letter for example an excellent quality of stamp cancellation regardless of the quality of the stamp is obtained. surface thereof (smooth, glossy, etc.). Furthermore, according to an essential advantage of the composition according to the invention, the marking, the printing, the obliteration obtained on the substrate, for example the postal article, the letter, especially on a stamp is indelible.

  For indelible, it is generally understood that the printing, the marking, the obliteration, carried out is not substantially eliminated from the substrate, for example from the postal article, the letter, the stamp, by immersion even prolonged (namely several hours or days, for example about 24 hours) in various aqueous and organic solutions, such as demineralised water, alcohols for example ethanol, methanol, methyl ethyl ketone, hexane, toluene, dimethylformamide, alkaline water at pH 11, bleach at 8 in water, etc. The invention will be better understood on reading the following description of embodiments of the invention, given by way of illustrative and non-limiting examples.

  The following ink compositions according to the invention were prepared by mixing the products mentioned in Table I, in the indicated proportions, which also gives the viscosity and the conductivity of the inks obtained.

Table I

  Constituents (percentages in N 1 N 2 N 3 N 4 N 5 masses) Pure propylene carbonate 85.5 91.4 88.9 83 82.9 (> 99%) Diethylene glycol ethyl ether 9 Dipropylene glycol 5 Tripropylene glycol methyl 8 ether (Dowanol TPM) Solvent black 3 black 3 1 grease (Black 860 Orient coils) Solvent Black 29 (Orasol 5 4.9 4 black RLI) Solvent Black 7 (Nigrosine 4 1 base) Solvent Black 28 (Orasol 1 2 black CN) Phenolic resin (PN 320 from 3 Solutia ) Phenolic resin (PN 630 of 2 Solutia)) Ketone resin (Resin SK - 4 Hüls) 2 8 Nitrocellulose (E15 of 2 Bergerac NC) Sodium thiocyanate 0.5 Potassium hexafluorophosphate 1 1 Ammonium hexafluorophosphate 0.5 1 Surfactant (Fluorad FC430) 0.1 0.1 0.1 0.1 0.1 Viscosity (mPa. $) 5.2 4.4 3.9 6.4 5. 1 Conductivity (pS / cm) 750 710 1180 1040 1160 The compositions according to Table I, in accordance with the invention, contain not more than 4% by weight of water, it seems to be due to the water present as unavoidable impurity.

  Each of these examples gives stable inks.

  The inks thus prepared have been tested in Imaje Series 7 printers and provide excellent print quality.

  Impressions made on stamps are at least as strong as ink stamps themselves to all kinds of aqueous and organic solutions such as: Demineralized water, methanol, ethanol, methyl ethyl ketone, hexane, toluene, dimethylformamide, alkaline water at pH 11, bleach at 8% in water.

  The inks of Examples 1 to 5 according to the invention were projected by ink jet in Imaje printers type Jaime 1000 on US stamps.

  The printed messages were a succession of points in a straight line.

  The stamps are as follows: 37 cts US (stars and stars) 23 Cts (George Washington) 37 Cts (Happy Birthday) 37 Cts (American Bat) 37 Cts (Chinese New Year 2003) 3 Cts (star) None of the different aqueous solutions and none of the organic solvents made it possible to dissolve the markings without degrading the patches themselves, even after prolonged immersion.

Claims (22)

  An ink composition for deviated continuous jet printing, liquid at room temperature, comprising: - a binder; one or more dyes and / or pigment (s); and - a solvent; wherein said solvent comprises more than 70% by weight - based on the total weight of the ink - of propylene carbonate, and less than 10% by weight, preferably less than 5%, more preferably less than 1%, and better 0% by weight of water.   An ink composition according to claim 1 comprising more than 80% by weight, preferably more than 85% by weight, more preferably more than 90% by weight of propylene carbonate.   Ink composition according to any one of claims 1 and 2 comprising at most 97% by weight, preferably at most 95% by weight of propylene carbonate.   4. The composition of any of the preceding claims wherein the flash point is greater than 600 ° C.   5. Composition according to any one of claims 1 to 4 comprising up to 20% by weight, preferably from 5 to 15% by weight of one or more other organic solvent (s) different ( s) propylene carbonate.   An ink composition according to claim 5, wherein said at least one organic compound solvent (s) is (are) selected from alcohols; ketones; alkylenes glycol ethers and esters thereof such as acetates; dimethylformamide; N-pyrrolidone; and carbonates other than propylene carbonate such as ethylene carbonate and dimethyl and diethyl carbonates; and their mixtures.   7. Composition according to claim 6, wherein said one or more other solvent (s) is (are) chosen from linear or branched aliphatic alcohols of 1 to 5 carbon atoms; ketones of 3 to 10 carbon atoms; monoalkyl (C1-C6) or dialkyl (C1-C6) ethers of alkylenes having 1 to 10 carbon atoms in the alkylene chain, such as ethylene glycol and propylene glycol; and esters thereof with carboxylic, saturated aliphatic acids of 1 to 6 carbon atoms.   8. Composition according to claim 6 or 7, wherein the amount of said other (s) organic solvent (s) is chosen so that the flash point of the composition is greater than 60 C.   An ink composition according to any one of the preceding claims, wherein said binder comprises one or more resin (s) or polymer (s).   The ink composition according to claim 9, wherein said resin (s) and / or polymer (s) is (are) selected from (meth) acrylic, vinyl, ketone, phenolic, cellulosic resins. , styrenics, epoxies, polyurethanes, styrene acrylates, and combinations of two or more thereof.   An ink composition according to any one of the preceding claims comprising from 0.1 to 30% by weight, preferably from 1 to 25% by weight, more preferably from 3 to 20% by weight, of binder.   An ink composition according to any one of the preceding claims, further comprising one or more plasticizers (s) at 0.1 to 20% by weight.   An ink composition according to any one of the preceding claims, wherein said one or more dyes and / or pigment (s) is (are) selected from dyes and pigments known as CI Solvent Dyes and CI Pigments, such as Solvent Black 29 CI, Solvent Black 7 CI, Solvent Black 28 CI, C. 1. Solvent Black 35, Solvent Blue 70 CI, Solvent Red 124 CI, Pigment Blue 60 dispersions or Pigment Blue 15.   14. A composition according to any one of the preceding claims, comprising from 0.05 to 25% by weight of dye (s) and / or pigment (s), preferably from 1 to 20%, more preferably from 3 to 10% by weight. % in weight.   Composition according to any one of the preceding claims, further comprising at least one conductivity salt in a proportion of 0.1 to 20% by weight, preferably 0.1 to 10% by weight, more preferably from 0.1 to 5% by weight.   The ink composition according to claim 15, wherein said conductivity salt is selected from alkaline, alkaline earth metal and single or quaternary ammonium salts, in the form of halides, perchlorates, nitrates, thiocyanates, formates. , acetates, sulfates hexafluorophosphates, hexafluoroantimonates and propionates.   An ink composition according to any one of the preceding claims which has a conductivity greater than 300 μS / cm at 20 ° C, preferably 500 μS / cm to 2,000 μS / cm.   Ink composition according to any one of the preceding claims, further comprising one or more additives selected from antifoaming agents, chemical stabilizers, UV stabilizers, surfactants, agents inhibiting corrosion by salts; bactericides, fungicides and biocides, and pH buffers.   19. A method of marking objects by projection on these objects of an ink by the deviated continuous jet technique, characterized in that the projected ink is an ink composition according to any one of claims 1 to 18.   20. Substrate characterized in that it is provided with a marking obtained by drying the ink composition according to any one of Claims 1 to 18.   21. Substrate according to claim 20, characterized in that the substrate is made of metal, for example aluminum, steel, glass, ceramic, a material containing cellulose such as possibly coated or glossy paper, cardboard or wood, of synthetic polymer (plastic), such as PVC, PET, polyolefin, such as polyethylene (PE), polypropylene (Pi)), Plexiglas, or any other non-porous or porous substance or composite of many of the previous materials.   22. Substrate according to claim 21, which is a postal item, a letter, a parcel, a postage stamp.