JP2013018939A - Inkjet ink and printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide ink which sufficiently has improved adhesion and washing resistance and solvent resistance after printing in the ink which has sufficiently well dissolved a resin having good solubility and has possessed stability in an inkjet printer.SOLUTION: The inkjet ink sufficiently having high adhesion to a material surface to be printed and washing resistance and solvent resistance after printing is attained when the inkjet ink allows a ketone-based solvent and a blocked isocyanate blended into the inkjet ink to be satisfactorily compatible with each other. That is, the inkjet ink is ink for an inkjet printer which includes the ketone-based solvent and a colorant, and further includes the blocked isocyanate. Thus, as shown in Fig.1(b), print dots in a data matrix printed are not dissolved even after being rubbed with a cotton swab impregnated with ethanol for twenty times.

Description

  The present invention relates to an ink used in an ink jet printer, and more particularly to an ink jet ink capable of forming a printed material having solvent resistance on the surface of a printing material, and a printing method using the same. is there.

In general, inkjet printers that can easily print variable information in a non-contact manner are widely used as recording methods for plastics, glass, metal, and the like. As inks used in such ink jet printers, inks in which oil-based dyes, vinyl chloride resins, vinyl acetate resins, acrylic resins, butyral resins, etc. are dissolved in solvents such as methyl ethyl ketone and alcohol are known. Incidentally, Patent Document 1 discloses an ink-jet ink using a phenol aldehyde resin. Patent Document 2 discloses ink for printing on glass and glass-coated ceramic. Patent Document 3 discloses an ink in which a polyamide resin is dissolved with a solvent. However, inks using these resins are designed to give sufficient stability and re-dissolvability in an ink jet printer, so that the stability in the printer is very good, but the surface of the substrate to be printed. With respect to the solvent resistance of the printed material formed on the ink, even if the ink is sufficiently dried, the ink easily dissolves.

In order to obtain such solvent resistance, there is a method of using a component that becomes insoluble after drying as an ink component. As an ink using this method, a so-called UV (ultraviolet ray) curable ink or an EB (electron beam irradiation) curable ink that irradiates ultraviolet rays or an electron beam to crosslink the monomer is known. For example, Patent Document 4 discloses a UV curable or EB curable ink using a low molecular weight polyfunctional monomer or a monofunctional monomer. Patent Document 5 discloses a UV curable ink that can cope with a printed circuit board and etching resistance. However, for UV curable inks, the UV irradiation apparatus is relatively expensive, and ozone is generated during UV irradiation, so that the printing environment requires a complicated and expensive configuration. On the other hand, the EB curable ink has a problem that the EB apparatus becomes more expensive and requires adjustment in a vacuum system or a nitrogen atmosphere, so that the introduction is not easy.

As a method for imparting solvent resistance, a curing agent is used, and a resin is reacted by the action of a catalyst or heat to impart solvent resistance or the like. For example, Patent Document 6 describes an acrylic resin and an epoxy resin, and shows a method in which a curing agent for epoxy resin is used in combination. Patent Document 7 discloses a method using a reaction promoting aid such as titanium tributyl phosphate. However, although the epoxy resin and the curing agent have good curability after printing, they are liable to cause gelation of the ink due to a temperature change in the ink jet printer, and it is not easy to obtain a stable ink.

As a countermeasure from such a viewpoint, Patent Document 8 discloses a method of using a blocked isocyanate and a catalyst as a surface treatment agent for imparting curability by low-temperature heating. This surface treating agent is used as a surface treatment in a part of the configuration of an ink jet printer, and there is no description that it is applied to ink for inkjet. On the other hand, for ink-jet ink, Patent Document 9 discloses an ink for a color filter using an active hydrogen group transparent resin and a blocked isocyanate. However, the present invention relates to ink for drop-on-demand, and the technical field is different from ink for continuous ink jet printers that dry quickly. The use of such inks in continuous ink jet printers may lead to inadequate conductivity due to inadequate control of printing, or easy use of conductive agents, which may cause aggregation and sedimentation. was there. Patent Document 10 discloses a water-based ink for drop-on-demand as a textile printing ink, and Patent Document 11 discloses a water-based ink using a blocked isocyanate that is cleaved at 100 ° C. or lower. Yes. These all relate to water-based inks for drop-on-demand, and cannot be applied to inks using ketone-based organic polar solvents such as MEK.

British Patent No. 1524881 (A) GB 1541937 (A) JP-T 09-507521 U.S. Pat. No. 4,303,924 (A) US Pat. No. 5,270,368 (A) British Patent No. 1595453 (A) British Patent No. 2161817 (A), (B) JP 09-011465 A JP 2009-086206 A JP 2003-268271 A JP 2004-269823 A

Although the present invention is an ink that contains a resin having excellent solubility and has stability in an ink jet printer, it has improved adhesion and has sufficient resistance to washing and solvent after printing. It is an object to obtain an ink having the above. In addition, in the ink as described above, the progress of the reaction over time is sufficiently controlled to prevent ink thickening and gelation inside the printer, and to obtain an ink that can be stably printed even in a continuous ink jet printer. With the goal. Another object of the present invention is to obtain an ink that can meet the demand for keeping the chlorine content in the ink at 900 ppm or less from the recent environmental response.

  As a result of intensive studies to achieve the above object, the present inventors have succeeded in well-matching a blocked isocyanate with a highly soluble ketone solvent preferably blended in an inkjet ink, As a result, it was possible to realize an ink-jet ink having high adhesion to the surface of the substrate to be printed and sufficient washing resistance and solvent resistance after printing.

That is, the ink-jet ink according to the present invention is an ink for an ink-jet printer comprising a ketone solvent and a colorant, and further comprises a blocked isocyanate.

  Further, in the above configuration, the blocking agent incorporated in the blocked isocyanate is one or more selected from the group consisting of diethyl malonate, dimethylpyrazole, methyl ethyl ketone oxime, and caprolactam.

  And in each said structure, it comprises the 1 type (s) or 2 or more types of resin chosen from the group which consists of a polyester resin, an acrylic resin, a phenol resin, an amine resin, a bullar resin, and a rosin modified maleic acid resin. .

  Further, in each of the above-described configurations, the blocked isocyanate is contained in an amount of 0.5 wt% to 5 wt% with respect to the total weight of the ink.

  In each of the above-described structures, the blocking agent incorporated in the blocked isocyanate contains dimethylpyrazole as a main component, and further includes one or more selected from the group consisting of diethyl malonate, methyl ethyl ketone oxime, and caprolactam. It is what is. The “main component” as used herein has a content exceeding 50% by weight based on the entire blocking agent.

  In each of the above-described configurations, the pigment is 2 to 15% by weight, the resin is 1 to 20% by weight, the blocked isocyanate is 0.1 to 5% by weight, and the conductive agent is 0.3 to 2% with respect to the total weight of the ink. .5% by weight, with the balance being a solvent containing a ketone solvent.

  Further, in each of the above-described configurations, the conductive agent is configured to be at least one of tetrabutylammonium hexafluorophosphate and tetraphenylboron quaternary ammonium.

  Moreover, the printing method which concerns on this invention sprays the ink droplet of the inkjet ink as described in any one of Claim 1 to 7 on the surface of a to-be-printed material using a continuous inkjet printer, and prints it. A printing process for forming a body, and a heating process for heating the printed body on the surface of the substrate to be printed in a temperature atmosphere of 130 ° C. or more and 250 ° C. or less for 15 minutes or more and 60 minutes or less.

  The ink-jet ink according to the present invention comprises a ketone solvent and a blocked isocyanate, so that printing on an ink-jet printer and predetermined heat treatment can be performed even on glass, metal, or a painted surface on the surface thereof. By applying the above, it is possible to obtain a printed material with high adhesion. In addition, the inkjet ink of the present invention is excellent in the ejection stability and re-dissolvability of the ink in the head, and can be used in the same manner as the inkjet ink containing a conventionally used solvent. In addition, the ink is thermally cured by heating, and can exhibit solvent resistance and washing resistance by a surfactant.

  In addition, the printing method according to the present invention includes a printing process using the ink-jet ink of the present invention and a heating process for heating the printed material on the surface of the substrate to be printed formed in the printing process. It can be realized with a configuration. While having such a simple configuration, it is possible to obtain printing characteristics such as good adhesion of the printed material to the surface of the printing material.

The ethanol resistance of the ink jet ink prepared according to Example 10 of the present invention was evaluated. (A) shows the ink jet ink of Example 10 applied to the coated surface of a glass plate having a gray paint on the plate surface. The data matrix is printed by spraying with a printer, and the surface state after rubbing three times with a cotton swab soaked in ethanol without heat-treating the coated surface of the glass plate is shown in the photograph. It is the figure which showed the surface state after printing a data matrix using the inkjet ink prepared by Example 10, heat-treating the glass plate coating surface, and rubbing 20 times with the cotton swab soaked in ethanol with the photograph. . The ultrasonic cleaning resistance of the ink-jet ink prepared according to Example 10 of the present invention was evaluated. (A) shows the continuous use of the ink of Example 10 on the coated surface of a glass plate coated with a gray paint on the plate surface. The surface state immediately after printing the data matrix by spraying with an ink jet type ink jet printer, (b) is a glass plate coated surface in the state (a) immersed in a nonionic active agent aqueous solution for more than 30 minutes It is the figure which showed the surface state which performed the sonication with the photograph. The adhesion of the ink jet ink prepared according to Example 10 of the present invention was evaluated. (A) is a continuous ink jet printer in which the ink of Example 10 is applied to the coated surface of a glass plate having a gray paint on the plate surface. The data matrix was printed by spraying, and the surface state before the data matrix was cured by heat treatment was shown as a photograph. (B) is the heat treatment from the state of (a), and the data matrix was cured. The figure which showed the surface state which gave the grid cut section later with the photograph, (c) is the figure which showed the surface state which stuck and peeled the cellophane tape on the glass plate painting surface of the state of (b) is there. The ink-jet ink prepared according to Example 10 of the present invention was evaluated for adhesion after storage under high-temperature and high-humidity conditions. (A) Example on a coated surface of a glass plate coated with a gray paint on the plate surface 10 is a diagram showing a surface state after a data matrix is printed by spraying 10 inks with a continuous ink jet printer and the data matrix is cured by heat treatment, and (b) is a cross-sectional view from the state of (a). The figure which showed the surface state after giving a cut section and storing it for 3 days under the high temperature and high humidity conditions of 65 degreeC humidity RH90%, (c) is a cellophane tape on the glass plate coating surface of the state of (b). It is the figure which showed the surface state which affixed and peeled off with the photograph.

An embodiment of the present invention will be described. The embodiment described below is merely one embodiment of the present invention, and does not limit the technical scope of the present invention.
Examples of the colorant used in the present invention include pigments and dyes. Both of these may be used alone or in combination. As the pigment, inorganic pigments and organic pigments can be used. Specific examples of the inorganic pigment used include titanium oxide, calcium carbonate, iron oxide, and cobalt blue. Examples of organic pigments include quinacridone, phthalocyanine, benzimidazolone, isoindolinone, quinophthalone, condensed azo, isoindoline, and diketopyrrolopyrrole. The above-mentioned pigments are preferable because they have good light resistance, but are not limited to the use of the above-mentioned pigments in applications that do not particularly require light resistance. As for titanium oxide, the pigment surface treated with an aluminum-based, zinc-based, or silica-based surface treatment agent will be described later with respect to dispersibility, sedimentation prevention, thickening over time, aggregation prevention, and the like. It is preferable in terms of stability with resin and blocked isocyanate.

  Specific examples of the above organic pigments include insoluble azo pigments such as toluidine red, toluidine maroon, Hansa Yellow, benzidine yellow and pyrazolone red, soluble azo pigments such as lithol red, heliobordeaux, pigment scarlet, and permanent red 2B, alizarin, indan Derivatives from vat dyes such as Throne and Thioindigo Maroon, Phthalocyanines such as phthalocyanine blue and phthalocyanine green, quinacridones such as quinacridone red and quinacridone magenta, perylenes such as perylene red and perylene scarlet, isoindolinone yellow, iso Isoindolinone type such as indolinone orange, pyranthrone type such as pyranthrone red, pyranthrone orange, thioindigo type, condensed azo type, benzimidazolone Examples of other pigments include flavanthrone yellow, acylamide yellow, quinophthalone yellow, nickel azo yellow, copper azomethine yellow, perinone orange, anthrone orange, dianthraquinonyl red, dioxazine violet, diketopyrrolopyrrole, etc. It is done.

When the above-mentioned pigment is represented by a color index (CI) number, C.I. I. Pigment Yellow 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 109, 110, 117, 125, 128, 129, 137, 138, 139, 147, 148, 151, 153, 154 181, 166, 168, 185, C.I. I. Pigment orange 16, 36, 43, 51, 55, 59, 61, C.I. I. Pigment Red 9, 48, 49, 52, 53, 57, 97, 122, 123, 149, 168, 177, 180, 192, 202, 206, 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240, C.I. I. Pigment violet 19, 23, 29, 30, 37, 40, 50, C.I. I. Pigment Blue 15, 15: 1, 15: 3, 15: 4, 15: 6, 22, 60, 64, C.I. I. Pigment green 7, 36, C.I. I. Pigment Brown 23, 25, 26, etc. can be exemplified.

These pigments are dispersed so that the average particle diameter (median diameter (D50) of cumulative distribution) measured with a particle size distribution meter is in the range of 10 to 300 nm and the maximum particle diameter is 1 μm or less. The average particle size of these pigments is preferably 0.3 μm or less. When the average particle size is larger than 0.3 μm, the dispersion stability of the ink is poor and the generation of sediments increases. In particular, when the maximum particle size is 1 μm or more, the precipitation of the pigment becomes remarkable and the printing stability is impaired. On the other hand, when the average particle size is 10 nm or less, there is no particular problem, but since the particle size is too fine, there is a possibility that deterioration in light resistance is likely to occur. As described above, the pigment used in the present invention is preferably fine pigment particles. However, in order to obtain an inkjet ink, it is preferable to perform high-speed stirring with a dispersing agent to be further added to form a stable dispersion. . Such a pigment is desirably contained in an amount of 0.5 to 20% by weight based on the total weight of the ink-jet ink in order to obtain a sufficient image density and a sufficient light resistance after recording.

In the present invention, it is also possible to use a dye. Such a dye is not particularly limited as long as it can be dissolved in the aforementioned ketone solvent. However, from the viewpoint of solvent resistance, when the solvent to be contacted after curing of the printed body is an alcohol, a solvent that is insoluble in the alcohol is preferable. For example, Solvent Yellow 2, 14, 16, 19, 21, 34, 48, 56, 79, 88, 89, 93, 95, 98, 133, 137, 147, Solvent Orange 5 6, 45, 60, 63, Solvent Red 1, 3, 7, 8, 9, 18, 23, 24, 27, 49, 83, 100, 111, 122, 125, 130, 132, 135, 195, 202 212, Solvent Blue 2,3,4,5,7,18,25,26,35,36,37,38,43,44,45,47,48,51,58,59,59: 1,63 64, 67, 68, 69, 70, 78, 79, 83, 94, 97, 98, 99, 100, 101, 102, 104, 105, 111, 112, 122, 124, 128, 129, 132, 136 , 137, 138, 139, 143, Solvent Green 5, 7, 14, 15,20,35,66,122,125,131, Solvent Black 1,3,6,22,27,28,29, Solvent Violet 13, Solvent Brown 1,53, etc. A mixture of the above can be used.
It is also possible to use a basic oily dye. Examples of such basic oily dyes include C.I. I. Basic Violet 3, C.I. I. Basic Red 1, 8, C.I. I. Basic Black2 etc. are mentioned.

  The above-mentioned blocked isocyanate is a compound having a protected isocyanate group obtained by reacting an isocyanate compound and a protective compound (blocking agent) by a conventional method. Such a blocked isocyanate is inactive at room temperature, but has a property that when heated, the protective group is dissociated and the isocyanate group is regenerated. For this reason, if it is the conditions which are not heated, it is possible to mix | blend with the compound which has an active hydrogen group previously.

  As the compound having an isocyanate group, one or two or more isocyanate groups may be contained in one molecule, and examples thereof include aliphatic, aromatic or alicyclic mono- or diisocyanate and triisocyanate compounds.

  Examples of the blocking agent for protecting the isocyanate group include alcohol compounds, phenol compounds, lactam compounds, oxime compounds, acetoacetic acid alkyl ester compounds, malonic acid alkyl ester compounds, phthalimide compounds, and imidazole compounds.

  In the ink state, the blocked isocyanate used in the present invention is sufficiently dissolved and stable in a ketone solvent that is a solvent component of the main ink. And this blocked isocyanate reacts with a part of the resin component described later or a part of the resin component when given any heat in the drying step after printing or the subsequent heating step, Alternatively, it reacts with a part of the substrate to be printed and works to strengthen the printed ink film. Since general isocyanates are highly reactive, the reaction is likely to proceed without the application of heat. However, blocked isocyanates can cause reactions by exceeding a certain temperature. Problems such as thickening and gelation can be prevented.

  As such blocked isocyanates, those in which dimethylpyrazole, diethyl malonate, methyl ethyl ketone oxime, caprolactam, etc. are incorporated as a blocking agent in the isocyanate molecular structure are known. These blocking agents can adjust the temperature at which the block dissociates depending on the type. However, in consideration of the temperature in the ink jet printer, suitability for storage temperature, actual post-treatment process, etc. The condition of dissociating and dissociating at 250 ° C. or lower is preferable from the viewpoint of energy efficiency.

  In order to impart suitability to such conditions, it is desirable to use, for example, dimethylpyrazole, diethyl malonate, methyl ethyl ketone oxime, caprolactam as a blocking agent, and among these, dimethylpyrazole is the main component. It is preferable to select. Diethyl malonate tends to crystallize the cured coating film, and may not be partly preferred as a coating film characteristic. Moreover, since methyl ethyl ketone oxime dissociates at a relatively high temperature, it requires a little more energy for curing. Further, the caprolactam system has a drawback that it tends to produce deposits (spots) in the equipment for curing treatment. Further, a block isocyanate of a system in which diethyl malonate, methyl ethyl ketone oxime, or caprolactam is partially mixed with dimethylpyrazole is preferable because appropriate curability and characteristics during curing can be desirably adjusted. The selection of these blocking agents needs to correspond to the long-term circulation in the printer and the heat treatment environment after printing. In addition, if the substrate of the substrate to be printed is pre-painted with a thermosetting material, it is necessary to set a category that does not deviate from the curing conditions, and it is easy to set a wide tolerance that easily matches such adjustments. Can use dimethylpyrazole. That is, in order to exhibit the effects of dissociation temperature, adhesion, and solvent resistance, a preferable blocking agent is selected.

  If a large amount of the above-mentioned blocked isocyanate is added to the ink, it leads to improvement of solvent resistance and coating film hardness, which will be described later. However, if the amount used is large, the stability of the ink is reduced (for example, increase in viscosity, aggregation) , Gelation) is likely to occur, and it is preferably used in the range of 0.1 to 5% by weight based on the total weight of the ink. If the blocked isocyanate exceeds 5% by weight, the stability of the ink itself is insufficient. On the other hand, when the blocked isocyanate is less than 0.1% by weight, no improvement in film strength that can be judged from solvent resistance or the like is observed. That is, the addition amount of the blocked isocyanate is preferably 0.5 to 2.5% by weight, more preferably 0.5 to 1.5% by weight from the balance with temperature or the balance with ink viscosity.

  As the resin component used in the present invention, at least one of a polyester resin, an acrylic resin, a phenol resin, an amine resin, a bullar resin, and a rosin-modified maleic resin can be used. These resins exhibit adhesion to various printed materials. When a dye is used as the colorant, the dye is sufficiently dissolved and compatible with each other to exhibit the fixing property. In the case of using a pigment, it not only has a fixability of the pigment, but also plays a part as a dispersant for dispersing the pigment. These resins are preferably those having good solubility in the ketone solvent which is the main solvent of the present invention. However, in the state after printing and after drying, insolubility, which is opposite to the re-solubility in the printer, is also required. For this reason, it must have solvent resistance with respect to the solvent which was easy to melt | dissolve by appropriate combination with the said block isocyanate and moderate heating.

In the combination of blocked isocyanate and resin, among the above resins, the combination of butyral resin and rosin modified maleic acid resin is easy to react with the isocyanate part after blocking agent dissociation in blocked isocyanate. Use is preferred. In this case, a butyral resin having an average molecular weight of 20000 or less and a hydroxyl group of 20% or more, more preferably 30% or more is suitable in terms of viscosity characteristics and reactivity with isocyanate.
The rosin-modified maleic resin contributes to good dispersion of the pigment in the same manner as the butyral resin. This rosin-modified maleic acid resin also has good characteristics in terms of re-dissolvability of ink in an ink jet printer. Therefore, by using a butyral resin and a rosin-modified maleic acid resin, it is possible to maintain stable dispersion even when a conductive agent is added as an ink for a continuous ink jet printer. That is, it is a preferable combination from the viewpoint of maintaining stable dispersibility in a system in which a pigment is dispersed. These resins are preferably used in an amount of 1 to 15% by weight based on the total weight of the ink because the viscosity needs to be matched to the suitability of the ink.
The butyral resin has a molecular weight of 10,000 to 30,000, preferably 15,000 to 20,000, a hydroxyl group of 20 to 40%, more preferably 35 to 40%, and a butyralization degree of 60 to 80. It is preferable for obtaining a general-purpose ink having wide properties. Other resins include amine resins (condensation resins of melamine and formaldehyde), polyester resins (polycondensates of polyvalent carboxylic acids and polyalcohols, unsaturated polyesters having unsaturated groups, etc.), phenolic resins (for example, Tamano PA, 135, 340, 350, 386 manufactured by Arakawa Chemical Co., Ltd.), acrylic resins (for example, ACRYDIC A-322, A-405, A-452, manufactured by DIC, and Dialnal RB50 manufactured by Mitsubishi Plastics, etc.) Can also be used.

The ink according to the present invention uses a ketone solvent as a main solvent, and can be suitably used for an ink jet printer, in particular, a continuous ink jet printer that is a continuous ejection type of charged dots. Therefore, a conductive agent is used for this ink in order to cope with adjustment of the deflection amount due to the electric field of the ink droplet ejected from the printer. As such a conductive agent, for example, ammonium thiocyanate, potassium thiocyanate, sodium thiocyanate, lithium nitrate, tetrabutylammonium hexafluorophosphate, tetrabutylammonium bromide, tetraphenylboron quaternary ammonium salt and the like can be used. Among these, when the stability of the ink is evaluated from the viewpoint of compatibility with the blocked isocyanate, organic conductive agents such as tetrabutylammonium hexafluorophosphate and tetraphenylboron quaternary ammonium are stable over the long term. This is preferable.
The above-mentioned conductive agent is used within the range of 0.5 to 2.5% by weight with respect to the total weight of the ink. If the content of the conductive agent is less than 0.5% by weight, sufficient conductivity may not be obtained, and the deflection in the printer may not be stably maintained. On the other hand, if the content of the conductive agent is more than 2.5% by weight, the compatibility with each material cannot be sufficiently maintained and the stability over time is lowered, resulting in an unstable printing state in the printer. There is a risk of inviting. For conductive agents other than those described above, care must be taken when adding them because they may cause poor dispersion or aggregation of the pigment.

  As the solvent used in the present invention, for example, ketones such as acetone, methyl ethyl ketone, dipropyl ketone, methyl isobutyl ketone and methyl isopropyl ketone are mainly used. Of these, methyl ethyl ketone can be preferably used in inks for continuous ink jet printers because of the solubility of resins, the dispersibility of pigments, the conductivity, and the drying properties of inks. Further, for example, ethyl acetate, acetic acid-n-propyl, butyl acetate, toluene, xylene, isopropyl alcohol, butanol, dioxane, 2- (methoxymethoxy) ethanol, 2-butoxyethanol, 2- (isopentyloxy) ethanol, 2- (Hexyloxy) ethanol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, liquid polyethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol , 1-ethoxy-2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene Recall monoethyl ether, low molecular weight polypropylene glycol, cyclopentanone and the like, can be used as part of the solvent with a ketone solvent.

The resin used in the present invention has the ability to improve dispersibility as well as adhesion, but a dispersant may be used to further improve the dispersibility of the pigment.
Examples of the dispersant for the pigment include a hydroxyl group-containing carboxylic acid ester, a salt of a long chain polyaminoamide and a high molecular weight acid ester, a salt of a high molecular weight polycarboxylic acid, a salt of a long chain polyaminoamide and a polar acid ester, and a high molecular weight. Unsaturated acid ester, polymer copolymer, modified polyurethane, modified polyacrylate, polyether ester type anionic activator, naphthalene sulfonic acid formalin condensate salt, special aromatic sulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphorus Examples include acid esters, polyoxyethylene nonylphenyl ether, stearylamine acetate and the like. Specifically, Anti-Terra-U, Anti-Terra-203 / 204, Disperbyk-101, 107, 110, 130, 161, 162, 163, 164, 165, 166, 170, 400, manufactured by BYK Chemie BYKUMEN, BYK-P104, P105, P104S, 240S, Lactimon, Efka CHEMICALS EFKA 44, 46, 47, 48, 49, 54, 63, 64, 65, 66, 71, 701, 764, 766, EFCA Polymer 100 , 150, 400, 401, 402, 403, 450, 451, 452, 453, 745, Floren TG-710, Flownon SH-290, SP-1000, Polyflow No. 50E, No. 300, Ajinomoto Finetech Co., Ltd. Ajisper PB821, Enomoto Kasei Co., Ltd. Disparon KS-860, 873SN, 874, # 2150, # 7004, Kao Co., Ltd. demall RN, N, MS, C, SN-B, EP, Homogenol L-18, Emulgen 920, 930, 931, 935, 950, 985, Acetamine 24, 86, Solsperse 5000, 7000, 13240, 13940, 17000, 22000, 24000, 28000, 32000, 38500, manufactured by Lubrizol Nikkor T106, MYS-IEX, Hexagline 4a-U and the like manufactured by the company can be exemplified.

Furthermore, it is also possible to use a silicon-based surfactant or a fluorine-based surfactant as a regulator for dot formation. In the case of using an inorganic pigment having a large specific gravity such as titanium oxide or iron oxide, it is possible to use an unsaturated carboxylic acid-based hard cake inhibitor in order to prevent hard cake formation due to sedimentation. Examples of the material to be printed according to the present invention include metal, glass, plastics, or a coated material coated on the surface of these materials and having a heat resistant temperature of 100 ° C. or higher.
The ink is sprayed onto such a substrate by an ink jet printer to form various codes such as characters, barcodes, and data matrix codes (printed bodies), and then a heating process at 100 ° C. or higher. Is passed over 10 to 60 minutes. A preferable heating temperature is 130 to 250 ° C, and more preferably 150 to 210 ° C. A preferable heating time is about 15 to 30 minutes. Such heating conditions are preferable from the viewpoint of solvent resistance, adhesion, and washing resistance with an aqueous surfactant solution, and sufficiently exhibit the accuracy of the reading rate with a reader that reads barcodes, data matrices, etc. Can do.

  The viscosity at 20 ° C. of the ink according to the present invention is preferably adjusted within the range of 3.2 to 4.8 mPa · s in order to widen an appropriate printable area in the ink jet printer. When the viscosity of the ink is less than 3.2 mPa · s, the formation of ink dots on the surface of the printing material becomes poor, and the density (print density) of the formed printed material becomes thin. On the other hand, when the viscosity of the ink exceeds 4.8 mPa · s, problems such as defective ejection of ink droplets and poor drying after printing are likely to occur.

Hereinafter, the present invention will be described in more detail with reference to some examples.
[Example 1]
Butyral resin (molecular weight = 19000, hydroxyl group content = 36%, acetyl group content = 3%, butyralization degree 63%) 4.2 parts by weight, Solsperz 24000 (dispersing agent: manufactured by Lubrizol) 0.5 parts by weight Solspers 5000 (dispersant: Lubrizol) 0.2 parts by weight and rosin-modified maleic resin 10 parts by weight are dissolved in 79.2 parts by weight of methyl ethyl ketone to form a solution, and carbon black ( (REGAL330R: manufactured by Cabot Corp.) 4.2 parts by weight was added and mixed by stirring, and this mixed solution was subjected to a horizontal sand mill to disperse carbon black. To this dispersion, 1 part by weight of a blocked isocyanate containing dimethylpyrazole as a blocking agent was added and mixed, and 0.7 part by weight of tetrabutylammonium hexafluorophosphate was further added, followed by high-speed stirring and mixing. Thereafter, the mixed dispersion was filtered with a filter having an opening of 1.0 μm to obtain an ink for an ink jet printer.
In the trial manufacture of the ink, it is possible to disperse all the components constituting the ink in one container and to disperse them all together. However, only a part of the pigment, dispersant, resin and solvent is used for the pigment. In order to obtain a stable ink, it is preferable that the dispersion is performed as a concentrated system, and after the dispersion, a blocked isocyanate and a conductive agent are added and mixed and dissolved.

  The obtained ink was sprayed onto a painted surface (example of the surface of an object to be printed) of a glass plate with a white paint on the plate surface using a continuous ink jet printer (model CCS300 manufactured by Kishu Giken Kogyo Co., Ltd.). A data matrix composed of a plurality of dots (example of printed body) was formed. The glass plate coated surface on which this data matrix was formed was heated in an oven at 170 ° C. for 15 minutes. The glass plate after the heat treatment was subjected to various physical property tests described in detail below.

  In Examples 1 to 9 and Comparative Examples 1 to 5, as shown in Tables 1 and 2, black or chromatic ink was prepared, and various pigments and dispersants, or dyes and resins were prepared. Ink has been prepared using a solvent comprising, a blocked isocyanate, a conductive agent, and MEK. The ink of Example 8 is blended with a fluorine-based activator. In Example 9, a dye is blended in place of the pigment and the dispersant.

  As shown in Table 2, in the inks of Comparative Examples 1 to 3, no blocked isocyanate was blended, and no heat treatment for thermosetting was performed. In the inks of Comparative Examples 4 and 5, blocked isocyanate is blended, but no ketone solvent is blended.

  In Examples 10 to 17 and Comparative Examples 6 to 9, white inks were prepared by blending a white pigment and a dispersant as shown in Tables 3 and 4. For these inks, a black or gray glass plate was used as the substrate. In the inks of Comparative Examples 6 to 9, a conductive agent different from the conductive agent used in the inks of Examples 10 to 17 is blended.

The outline of the physical property test shown in each table is described below.
[Viscosity] is measured at 20 ° C. using an EH viscometer.
[Conductivity] is measured at 20 ° C. using a conductivity meter. In a continuous ink jet printer, a conductivity of 0.5 mS / cm or more is preferable for accurate dot deflection control.
[Dispersibility] is an evaluation of whether or not the pigment resin liquid is in a state of fluidity with little residue and coarse particles remaining when dispersed with a horizontal sand mill. Those with a very good dispersion state including the average particle diameter were marked with “◎”, and those with good drawdown coating surface condition and fluidity during dispersion were marked with “◯” and were not dispersed. Was “x”, and the agglomerated state was “aggregated”. It was determined whether or not the ink using the dye was “dissolved”.
[Average particle diameter] is indicated by the particle diameter (nm) of D50 measured with a particle size distribution meter of a laser detection system (UPA-150 manufactured by Nikkiso Co., Ltd.).

[Discharge stability] was carried out by printing on the resin-coated surface of the glass substrate surface with the continuous ink jet printer (CCS3000P manufactured by Kishu Giken Kogyo Co., Ltd.) and visually evaluating the state of the printed body. Is. Also, the ejection characteristics were evaluated by combining the ejection state of the nozzles during continuous printing according to the state of the obtained printed material. “○” indicates that each print dot has been printed correctly at the specified position. “D” may occur during printing, or each print dot may be printed at the specified position. What did not exist was set as "x". Further, the printed two-dimensional barcode was read by a reader to confirm the reading accuracy. Those with normal reading were marked with “◯”, and those with abnormal reading were marked with “X”.
[Re-solubility] is obtained by applying ink to a nozzle plate of a continuous ink jet printer and air-drying, and then spraying another ink on the dry ink on the next day to confirm dissolution of the dry ink. Those with good solubility were marked with “◯”, and those with poor solubility were marked with “x”.
[Storage stability] is obtained by enclosing the ink in a sealed container and storing it at 45 ° C., and confirming the appearance and viscosity change of the ink after two months. The case where the appearance and viscosity did not change more than a predetermined value (thickening of 8% or more) was rated as “◯”, and the value which changed more than a predetermined value was marked as “X”.

[Thermosetting] is a condition for confirming the curability at 150 ° C. for 30 minutes, the curability at 170 ° C. for 30 minutes, and the curability at 200 ° C. for 15 minutes as the conditions for thermally curing the printed body after printing. It is. This thermosetting is confirmed by applying ethanol to the cured surface cured by heat and checking whether or not the thermally cured printing body is dissolved. Those that did not dissolve were marked with “◯”, and those that partially dissolved were marked with “x”.
[Alcohol resistance] is the result of rubbing the surface of the printed material after the print body is thermally cured with a cotton swab soaked in ethanol 10 to 20 times to confirm dissolution or peeling of the printed dots on the surface of the printed material. . The case where there was no peeling was indicated as “◯”, and the case where there was peeling was indicated as “x”. For the white ink (Examples 10 to 17 (Table 3)), a reading test of the two-dimensional bar code after being immersed in alcohol was performed, and the one having a faster reading confirmation speed was further marked with “◎”.
[Detergency] is a two-dimensional bar code printed by immersing a printed material on which a two-dimensional barcode or data matrix is printed in a 0.25% nonionic active agent aqueous solution and performing a cleaning test by ultrasonic irradiation for 15 minutes. It evaluates whether a code or a data matrix can be read by a reader. Those with no reading abnormality were marked with “◯”, and those with reading abnormality were marked with “X”.
For [Adhesion], when cellophane tape is applied to the surface of the substrate on which the data matrix is printed, and the cellophane tape is peeled off, the print dots (printed material) that make up the data matrix are peeled off. It is to evaluate whether or not. The case where the printed dot-printed body was not peeled was designated as “◯”, and the case where the printed dot printed matter was peeled was designated as “X”.
In each table, the numerical values shown in the prescription column all represent weight% with respect to the total weight of the ink.

  As shown in Table 1, the inks obtained in Examples 1 to 9 described above had poor ethanol resistance and washing resistance results after printing on the surface of the substrate and before heat treatment. , Butyral resin, rosin-modified maleic acid resin, blocked isocyanate, main solvent MEK, and a suitable conductive agent were contained in a suitable formulation ratio, and thus showed good characteristics after heat treatment. At the same time, the storage stability and the long-term printing stability in the printer also show good characteristics.

  On the other hand, since the inks of Comparative Examples 1 to 3 did not use blocked isocyanate and were not naturally subjected to thermosetting treatment, the ethanol resistance was poor. Since the blocked isocyanate was not used and was not thermally cured, the ethanol resistance was poor. The ink of Comparative Example 4 uses a blocked isocyanate, but does not use a ketone solvent and a conductive agent, so that it is not suitable for use in a continuous ink jet printer and re-dissolvability is not good. The ink of Comparative Example 5 uses a blocked isocyanate, but does not use a ketone solvent. Therefore, the ink is not compatible with ammonium thiocyanate, which is a conductive agent, and a stable ink cannot be obtained. Solubility was not good either.

  On the other hand, since the ink of Example 10 contains a butyral resin and a rosin-modified maleic acid resin as shown in Table 3, the dispersibility and re-solubility are good, and the conductive agent is also good. Is shown. The blocked isocyanate using dimethylpyrazole as a blocking agent also showed good thermosetting properties, and also had good alcohol resistance and washing resistance. The ink of Example 11 is as good as Example 10. However, since the viscosity of the butyral resin is slightly higher, the viscosity is slightly increased, and the reaction portion with the blocked isocyanate is reduced by the amount of hydroxyl groups. This is more preferable as the total characteristic than Example 11. The ink of Example 12 is not as excellent in dispersibility and storage stability as the ink of Example 10 because the surface treatment of titanium oxide is subtly affected, but otherwise exhibits good characteristics. ing. The ink of Example 13 does not use the butyral resin, but the dispersibility and curability are not as good as those of Example 10, but otherwise have good characteristics. The ink of Example 14 shows the same stability as that of Example 10 although the type of conductive agent is different from that of Example 10. In addition, it is necessary to re-disperse and use titanium oxide that has settled during standing storage because the hard cake inhibitor is not contained. The inks of Examples 15-16 are somewhat inferior in dispersibility and resolubility compared to Example 10 containing a butyral resin and a rosin-modified maleic resin, but still exhibit generally good properties. Since the ink of Example 17 uses a blocked isocyanate whose cap agent is a caprolactone, the curing temperature must be increased, but the thermal curing at a high temperature was good.

Here, the ink of Example 10 is ejected from a continuous ink jet printer, and the data matrix printed on the glass plate coating surface is shown in the photograph.
FIG. 1 shows the evaluation of ethanol resistance of a printed material formed with the ink of Example 10. FIG. 1A shows the ink of Example 10 on the painted surface of a glass plate with a gray paint on the plate surface. The surface state after printing the data matrix by spraying with a continuous ink jet printer and rubbing it with a cotton swab dipped in ethanol without heat treatment of the coated surface of the glass plate is shown. According to it, the data matrix disappears even after only 3 rubbing. FIG. 5B shows the surface state after printing the data matrix using the same ink, heat-treating the glass plate coating surface, and rubbing it 20 times with a cotton swab dipped in ethanol. According to this, the solvent resistance to alcohol was high, and the printing dots of the data matrix did not dissolve even after 20 times of rubbing.
FIG. 2 shows an evaluation of the ultrasonic cleaning resistance of a print formed with the ink of Example 1. FIG. 2A shows Example 10 on the coated surface of a glass plate having a gray paint on the plate surface. The ink is sprayed with a continuous ink jet printer and the surface of the unheated surface is shown immediately after printing the data matrix. FIG. 6B shows the surface state in which the glass plate coated surface in the state of FIG. 6A is immersed in a nonionic activator aqueous solution and subjected to ultrasonic treatment for 30 minutes. It remains as it is immediately after printing without being washed away.

FIG. 3 shows an evaluation of the adhesion of a printed material formed with the ink of Example 10, and FIG. 3A shows the ink of Example 10 on the painted surface of a glass plate coated with a gray paint on the plate surface. A data matrix is printed by spraying with a continuous ink jet printer, and the surface state before curing by heat treatment is shown. FIG. 4B shows a surface state in which a grid is cut after the data matrix is cured by performing a heat treatment from the state of FIG. The figure (c) shows the surface state when the cellophane tape is attached to the glass plate coated surface in the state of the figure (b) and peeled off, but no peeling of the printed dots of the data matrix is observed. It indicates that the adhesion is high.
FIG. 4 is an evaluation of the adhesion after storing the printed material formed with the ink of Example 10 under high temperature and high humidity conditions. FIG. 4 (a) shows a glass plate having a gray paint on the plate surface. The surface state after the data matrix was printed by spraying the ink of Example 10 with the continuous inkjet printer on the coating surface, and the data matrix was hardened by heat processing is shown. FIG. 4B shows the surface state when the grid is cut from the state of FIG. 5A and stored for 3 days under a high temperature and high humidity condition of a temperature of 65 ° C. and a humidity of RH 90%. FIG. 2C shows the surface state when the cellophane tape is attached to the glass plate coating surface in the state of FIG. The photo in (c) is somewhat unclear, but no peeling of the printed dots in the data matrix is observed, indicating high adhesion even under high temperature and high humidity conditions.

  On the other hand, as shown in Table 4, the inks of Comparative Examples 6 to 9 are different in the type of conductive agent when the dispersibility is evaluated by changing the type of resin and the type of conductive agent for the white ink. Aggregation was observed, and a lack of stability was observed when used in a continuous ink jet printer.

  In addition, unlike the ink containing the conventional vinyl chloride / vinyl acetate copolymer resin, each of the inks of Examples 1 to 17 described above had a chlorine level significantly lower than 900 ppm. The result is obtained.

In each arrangement described above, those comprising polyester resins, acrylic resins, phenolic resins, amine resins, the one selected from the group consisting of blanking switch butyral resins and rosin-modified maleic acid resins or two or more resins It is.

The resin component used in the present invention, polyester resins, among acrylic resins, phenolic resins, amine resins, blanking Ji Lal resins, rosin-modified maleic acid resin, it is possible to use at least one. These resins exhibit adhesion to various printed materials. When a dye is used as the colorant, the dye is sufficiently dissolved and compatible with each other to exhibit the fixing property. In the case of using a pigment, it not only has a fixability of the pigment, but also plays a part as a dispersant for dispersing the pigment. These resins are preferably those having good solubility in the ketone solvent which is the main solvent of the present invention. However, in the state after printing and after drying, insolubility, which is opposite to the re-solubility in the printer, is also required. For this reason, it must have solvent resistance with respect to the solvent which was easy to melt | dissolve by appropriate combination with the said block isocyanate and moderate heating.

[Thermosetting] is a condition for confirming the curability at 150 ° C. for 30 minutes, the curability at 170 ° C. for 30 minutes, and the curability at 200 ° C. for 15 minutes as the conditions for thermally curing the printed body after printing. It is. This thermosetting is confirmed by applying ethanol to the cured surface cured by heat and checking whether or not the thermally cured printing body is dissolved. Those that did not dissolve were marked with “◯”, and those that partially dissolved were marked with “x”.
[Alcohol resistance] is the result of rubbing the surface of the printed material after the print body is thermally cured with a cotton swab soaked in ethanol 10 to 20 times to confirm dissolution or peeling of the printed dots on the surface of the printed material. . The case where there was no peeling was indicated as “◯”, and the case where there was peeling was indicated as “x”. For the white ink (Examples 10 to 17 (Table 3)), a reading test of the two-dimensional bar code after being immersed in alcohol was performed, and the one having a faster reading confirmation speed was further marked with “◎”.
[Detergency] is a two-dimensional bar code printed by immersing a printed material on which a two-dimensional barcode or data matrix is printed in a 0.25% nonionic active agent aqueous solution and performing a cleaning test by ultrasonic irradiation for 15 minutes. It evaluates whether a code or a data matrix can be read by a reader. Those with no reading abnormality were marked with “◯”, and those with reading abnormality were marked with “X”.
For [Adhesion], when cellophane tape is applied to the surface of the substrate on which the data matrix is printed, and the cellophane tape is peeled off, the print dots (printed material) that make up the data matrix are peeled off. It is to evaluate whether or not. What there was no separation of the printing dot as "○", was what was peeling as "×".
In each table, the numerical values shown in the prescription column all represent weight% with respect to the total weight of the ink.

Claims (8)

An ink for an ink jet printer comprising a ketone solvent and a colorant, wherein the ink further comprises a blocked isocyanate. The ink-jet ink according to claim 1, wherein the blocking agent incorporated in the blocked isocyanate is one or more selected from the group consisting of diethyl malonate, dimethylpyrazole, methyl ethyl ketone oxime and caprolactam. The inkjet according to claim 1 or 2, comprising one or more resins selected from the group consisting of polyester resins, acrylic resins, phenol resins, amine resins, bullar resins, and rosin-modified maleic acid resins. For ink. The inkjet ink according to any one of claims 1 to 3, wherein the blocked isocyanate is contained in an amount of 0.5 wt% to 5 wt% with respect to the total weight of the ink. The blocking agent incorporated in the blocked isocyanate contains dimethylpyrazole as a main component, and further contains one or more selected from the group consisting of diethyl malonate, methyl ethyl ketone oxime and caprolactam. The inkjet ink according to any one of 4 to 4. 2 to 15% by weight of pigment, 1 to 20% by weight of resin, 0.1 to 5% by weight of blocked isocyanate, and 0.3 to 2.5% by weight of conductive agent, respectively, based on the total weight of the ink. The ink for inkjet according to any one of claims 1 to 5, wherein the balance is a solvent containing a ketone solvent. The inkjet ink according to claim 6, wherein the conductive agent is at least one of tetrabutylammonium hexafluorophosphate and tetraphenylboron quaternary ammonium. A printing step of forming a printing body by spraying ink droplets of the ink-jet ink according to any one of claims 1 to 7 onto a surface of a substrate using a continuous inkjet printer; And a heating step of heating the printed material on the surface of the printed material in a temperature atmosphere of 130 ° C. or higher and 250 ° C. or lower for 15 minutes or more and 60 minutes or less.