JP5799033B2 - Ink jet ink and printing method - Google Patents

Description

  The present invention is an ink used in a so-called drop-on-demand (hereinafter, abbreviated as “DOD”) type ink jet printer in which only ink droplets necessary for printing are ejected from a nozzle each time. In particular, an inkjet capable of forming a printed material having solvent resistance on the surface of a substrate to be printed, and more specifically, marking a disqualified product generated in a manufacturing process on a semiconductor wafer or the like. The present invention relates to a printing ink and a printing method using the same.

  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 an 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. By the way, 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. As for the solvent resistance of the printed material formed on the surface of the ink, even if the ink is sufficiently dried, the ink easily dissolves.

  In order to obtain such solvent resistance, there is an ink technique in which a component that becomes insoluble after drying is used as an ink component. As inks using this technology, so-called UV (ultraviolet ray) curable inks and EB (electron beam irradiation) curable inks in which monomers are cross-linked when irradiated with ultraviolet rays or electron beams are 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 is more expensive and adjustment in a vacuum system or a nitrogen atmosphere is required, so that it is not easy to employ the apparatus. In addition, in the method using ultraviolet rays or electron beams, it is also suspected to cause damage to parts for specific applications related to semiconductors.

  Further, as a method for imparting solvent resistance, a curing agent is used, and a resin reacts 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, the epoxy resin and the curing agent have good curability after printing, but are liable to cause gelation of the ink due to a temperature change in the ink jet printer, and a stable ink cannot be easily obtained.

  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, it is a method using a water-based urethane resin, and is a method specialized for a color filter that requires the combined use of a catalyst. That is, the technical field is different from the ink used for marking on a semiconductor wafer or the like, which is performed without using a catalyst or the like. Patent Document 10 discloses a water-based ink for a DOD ink jet printer as a textile printing ink. Patent Document 11 discloses a water-based ink using a blocked isocyanate that is cleaved at 100 ° C. or lower. All of the techniques described in Patent Documents 10 and 11 relate to water-based ink for DOD, and cannot be applied to ink using a solvent having a boiling point of 120 ° C. or higher. Moreover, the technical field differs from the ink for marking on a semiconductor wafer or the like.

  On the other hand, conventionally, a marking method using a capillary method has been generally used for marking a disqualified portion of a microchip such as a semiconductor wafer. However, since this method has a very slow processing speed, studies on an inkjet method have been underway. Such a technique is disclosed in Patent Documents 12, 13, 14, 15, 16, 17, 18.19, and the like. However, even in the technologies described in these patent documents, there is no specific description of ink for ink jet that can cope with a disqualified portion of a microchip such as a semiconductor wafer. In addition, even if there is some description to suggest, it does not correspond to the environmental change in the semiconductor inspection equipment, does not have solvent resistance after printing, There was no indication of suitability.

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 Japanese Patent Laid-Open No. 11-163061 JP 2000-293809 A JP 2001-267380 A JP 2002-280276 A JP 2006-351772 A JP 2009-105210 A JP 2009-170712 A JP 2010-219133 A

  The present invention obtains an ink having sufficient adhesion and improved solvent resistance after printing, although it is an ink that sufficiently contains a resin having excellent solubility and has stability in an ink jet printer. For the purpose. In addition, in the ink as described above, it is possible to sufficiently control the progress of the reaction over time, prevent ink thickening and gelation inside the printer, and obtain an ink that can be stably printed even in a DOD type ink jet printer. With the goal. It is another object of the present invention to provide an ink jet ink that is adaptable to temperature changes in a semiconductor inspection apparatus.

  As a result of intensive studies to achieve the above object, the present inventors have succeeded in successfully adapting a blocked isocyanate with a high-boiling solvent having high solubility that is preferably blended in an ink jet ink. As a result, an ink-jet ink having sufficient adhesion to the surface of the substrate and sufficient solvent resistance after printing can be realized.

That is, the inkjet ink according to the present invention includes a colorant, a solvent having a boiling point of 120 ° C. or higher, a resin, and a blocked isocyanate , and an ink viscosity at 60 ° C. of 8 mPa · s to 15 mPa · s. The blocking agent incorporated in the blocked isocyanate is dimethylpyrazole, the resin is a butyral resin, or a butyral resin and a rosin-modified maleic acid resin, and the solvent is 2- It is characterized by containing phenoxyethanol as a main component .

Then, before Ki構 formed, total ink weight, the colorant 1 to 10 wt%, the resin 0.3 to 20 wt%, a blocked isocyanate 0.1-7 wt%, and containing respectively, the balance Is a solvent.

In addition, a printing method according to the present invention uses a drop-on-demand ink jet printer to spray ink droplets of the ink jet ink according to claim 1 or 2 onto the surface of a semiconductor wafer to obtain a printed material. A printing process to be formed; and a heating process in which the printed material on the surface of the semiconductor wafer is heated in a temperature atmosphere of 180 ° C. or higher and 250 ° C. or lower for more than 10 minutes and not more than 60 minutes.

  The ink-jet ink according to the present invention comprises a resin and a blocked isocyanate, so that printing is performed by an ink-jet printer and a predetermined heat treatment is performed even on glass, metal, or a painted surface on the surface thereof. Thus, a printed material with high adhesion can be obtained. 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, washing resistance by a surfactant, and the like. In addition, the heat resistance is improved.

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 body on the surface of the semiconductor wafer formed in the printing process. Can be realized. While having such a simple configuration, printing characteristics such as good adhesion of the printed body to the surface of the semiconductor wafer can be obtained.

FIG. 3 is a photograph showing a state in which ink according to Example 1 is sprayed onto the surface of a silicon wafer by a DOD type ink jet printer to print circular black spots, and the printed black spots are cured by heat treatment. FIG. 4 is a photograph showing a state in which low-viscosity ink generally used for a DOD type ink jet printer is used to print circular black dots on the surface of a silicon wafer by the same DOD type ink jet printer as in Example 1. .

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 can be used alone or in a mixture of the two. Among these pigments, inorganic pigments and organic pigments can be used. Specific examples of the inorganic pigment used include titanium oxide, calcium carbonate, iron oxide, cobalt blue and the like. Examples of the organic pigment include pigments such as quinacridone, phthalocyanine, benzimidazolone, isoindolinone, quinophthalone, condensed azo, isoindoline, and diketopyrrolopyrrole. Each of the above-mentioned pigments is preferable because it has good light resistance, but is not limited to the use of the above-described pigment 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 is described later in terms of dispersibility, sedimentation prevention, thickening over time, and aggregation prevention. In terms of stability with the resin and blocked isocyanate.

  Specific examples of the organic pigments described above 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. Derivatives from vat dyes such as Indanthrone 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 Isoindolinone such as isoindolinone orange, pyranthrone such as pyranthrone red, pyranthrone orange, thioindigo, condensed azo, benzimidazolo 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.

  The above-mentioned pigments are represented by, for example, the following color index names of Color Index International (CI). That is, C.I. I. The color index names of pigment yellow are 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, and the like.

  These pigments are prepared such that the average particle diameter (median diameter (D50) of cumulative distribution) measured by 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 diameter is larger than 0.3 μm, the dispersion stability of the ink is poor, and the generation of precipitates 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 ink-jet ink, it is necessary to stir at high speed with a dispersing machine together with a dispersant to be added to form a stable dispersion. preferable. 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 sufficient light resistance after recording.

In the present invention, it is preferable to use a dye from the temperature change of the printing environment. Such a dye is not particularly limited as long as it can be dissolved in a solvent having a boiling point of 120 ° C. or higher. 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. As such a dye, for example, Solvent Yellow 2, 14, 16, 19, 21, 34, 48, 56, 79, 88, 89, 93, 95, 98, 133, 137 represented by the following color index names are used. , 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. These can be used alone or in admixture of two or more.
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.
In the optical reading process, which is a subsequent process, when a reflection density in the near-infrared region is required, it is preferable to use carbon black or an azine dye (nigrosine dye).

  The above-mentioned blocked isocyanate is a compound obtained by reacting an isocyanate compound and a protective compound (blocking agent) by a conventional method. That is, it is a compound having a protected isocyanate group. Such a blocked isocyanate is inactive at room temperature, but has a property that when heated, the protecting group is dissociated and the isocyanate group is regenerated. Therefore, it can be preliminarily blended with a compound having an active hydrogen group as long as it is not heated.

  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 that protects 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 solvent having a boiling point of 120 ° C. or higher, which is a solvent component of the main ink. Then, this blocked isocyanate, together with the resin component described in detail later, or a part of the resin component when any heat is applied in the drying step after printing or the subsequent heating step It reacts or reacts with a part of the substrate to be printed, thereby exhibiting a function of strengthening the printed ink film. Since general isocyanate is rich in reactivity, the reaction is likely to proceed without application of heat. However, since the blocked isocyanate causes a reaction when a certain temperature is exceeded, problems such as increase in viscosity and gelation due to a natural reaction over time can be prevented.

Such blocked isocyanate, dimethylpyrazole, diethyl malonate, methyl ethyl ketone oleate ketoxime, a blocking agent exemplified by caprolactam, those incorporated into the isocyanate molecular structure is 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., it causes dissociation at 100 ° C. or higher and dissociation at 250 ° C. or lower from the viewpoint of energy efficiency. Is preferred.

To impart suitability to such conditions as the blocking agent, it is preferable to select a di-methylpyrazole. Incidentally, the diethyl malonate system is not preferred as the characteristics of the coating film because the cured coating film is easily crystallized. Further, since methyl ethyl ketone oxime is dissociated at a relatively high temperature, a little more energy is required 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-coated with a thermosetting material, it is necessary to set a category that does not deviate from the curing conditions. As an easy one, dimethylpyrazole can be used. That is, in order to exhibit the effects of dissociation temperature, adhesion, and solvent resistance, it is necessary to select a preferable blocking agent.

  Addition of the above-mentioned blocked isocyanate to the ink leads to improvement of solvent resistance and coating film hardness, which will be described later, if the addition amount is increased. However, if the amount of the blocked isocyanate used is large, the stability of the ink (for example, increase in viscosity, aggregation, gelation, etc.) is likely to occur. It is preferable to use it. When the amount of the blocked isocyanate exceeds 7% by weight of the total weight of the ink, the stability of the ink itself is insufficient. On the other hand, when the addition amount of the blocked isocyanate is less than 0.1% by weight of the total weight of the ink, no improvement in film strength that can be judged from solvent resistance or the like is observed. That is, the amount of blocked isocyanate added is determined from the balance with temperature or the balance with ink viscosity, but is preferably 0.5 to 7% by weight, more preferably 0.5 to 5% by weight based on the total weight of the ink. More preferred.

The resin component used in the present invention, butyral resin, or can be used butyral resins and rosin-modified maleic acid resins. These resins improve the adhesion to various printed materials. Further, when a dye is used as the colorant, the resin dissolves the dye sufficiently and is compatible with each other to improve the fixing property. When a pigment is used, the resin plays a part of the role as a dispersant for dispersing the pigment as well as the fixing property of the pigment. These resins preferably have good solubility in a solvent having a boiling point of 120 ° C. or higher, 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, an appropriate combination with the blocked isocyanate must be selected, and by applying an appropriate heat treatment, solvent resistance to a solvent that is easily dissolved must be provided.

In the combination of blocked isocyanate and resin, when combining with butyral resin or rosin modified maleic acid resin among the above resins, use of butyral resin is easy because reaction with isocyanate part after blocking agent dissociation in blocked isocyanate is easy. 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 good viscosity characteristics and high 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 dissolution and dispersion as an ink for an 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 for an ink jet printer.
The use of a butyral resin having 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 degree of butyralization of 60 to 80 is applicable to the printing material. This is preferable for obtaining a wide range of general-purpose inks. Examples of other resins include amine resins (condensation resin of melamine and formaldehyde), polyester resins (polycondensates of polyvalent carboxylic acids and polyalcohols, unsaturated polyesters having unsaturated groups, etc.), phenol resins ( For example, Tamanol PA, 135, 340, 350, 386 manufactured by Arakawa Chemical Co., Ltd.), acrylic resin (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 solvent having a boiling point of 120 ° C. or higher as a main solvent, and can be suitably used for an inkjet printer, particularly a DOD-type inkjet printer using a piezo element.

The solvent used in the present invention is mainly composed of a solvent having a boiling point of 120 ° C. or higher, and the drying of ink at the nozzle portion of the DOD type ink jet printer can be suppressed as much as possible. Even if the temperature at the time of ink ejection is relatively high, drying of the nozzle portion can be suppressed as much as possible. It is also possible to increase the solubility of an azine dye having absorption in the near infrared region as a dye. In addition, since use environment may become high temperature, in order to reduce solvent odor, a solvent system with little odor is preferable.
Examples of the solvent include diacetone alcohol, benzyl alcohol, etc. 2-diphenoxyethane Tano Le and the like. Of these, a solvent mainly composed of 2-phenoxyethanol can be used. By using these solvents, it is possible to form good dots on the semiconductor wafer. That is, these can be preferably used as the solvent for the ink of the DOD type ink jet printer from the viewpoint of the solubility of the resins, the dispersibility of the pigment, and the ink drying property.

  Furthermore, 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 Glycol monoethyl ether, low molecular weight polypropylene glycol, cyclopentanone diacetone alcohol, benzyl alcohol, 2-phenoxyethanol, at least one of the tri-hexanediol, it can also be used as part of the 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 are exemplified.

Furthermore, a silicon-based surfactant or a fluorine-based surfactant can be used as an adjusting agent for adjusting the dot formation state. In the case of using an inorganic pigment having a large specific gravity such as titanium oxide or iron oxide, an unsaturated carboxylic acid-based hard cake inhibitor can be used 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 described above is sprayed onto an object to be printed such as a semiconductor wafer by an ink jet printer to print various codes such as characters, bar codes, and data matrix codes (examples of the printed material according to the present invention). ) Is then formed, and then a heat treatment is performed to pass through a heated atmosphere at 100 ° C. or higher for 10 to 60 minutes. A preferable heating temperature is 120 to 250 ° C, and more preferably 150 to 210 ° C. A preferable heating time is about 15 to 30 minutes. Adopting such heating conditions is preferable from the viewpoint of obtaining solvent resistance, adhesion, and washing resistance with an aqueous surfactant solution, and reading barcodes, data matrices, etc., including authentication confirmation of the presence or absence of marking The accuracy of the reading rate on the machine can be fully exhibited. Moreover, it can respond also to alcohol washing and wiping off in a later process.

  The viscosity of the ink according to the present invention is preferably adjusted within the range of 8 to 130 mPa · s in order to widen an appropriate printable area in the ink jet printer. If the viscosity of the ink is less than 8 mPa · s, it is disadvantageous in that the printer installation environment is limited to a low temperature environment. In addition, the formation of ink dots on the surface of the printing medium becomes poor, and even if dots are formed, there is a problem that the density (print density) of the printed body becomes thin. On the other hand, if the viscosity of the ink exceeds 130 mPa · s, the heating temperature at the head must be further increased, and ink stability cannot be obtained. In addition, problems such as ink droplet ejection failure and drying failure after printing are likely to occur. Therefore, when the printing purpose is used in a semiconductor inspection apparatus such as a semiconductor wafer, the viscosity at 60 ° C. is adjusted to 8 to 15 mPa · s so that it can cope with a change in environmental temperature. Ink is preferred.

Hereinafter, the present invention will be described in more detail with reference to some examples.
[Example 1]
A solution obtained by dissolving 1.8 parts by weight of butyral resin (molecular weight = 19000, hydroxyl group content = 36%, acetyl group content = 3%, butyralization degree = 63%) in 89.1 parts by weight of 2-phenoxyethanol. Then, 4.1 parts by weight of nigrosine base EX (manufactured by Orient Chemical Co., Ltd.) was added to this solution, heated to 60 ° C., and mixed by stirring to obtain a mixed solution. After cooling this mixed solution to room temperature, 5 parts by weight of a blocked isocyanate containing dimethylpyrazole as a blocking agent was added and mixed, followed by high-speed stirring and mixing. Thereafter, the mixed solution was filtered through a filter having an opening of 1.0 μm to obtain an ink for an ink jet printer. The viscosity of the entire ink at 60 ° C. was 11.7 mPa · s, and the viscosity at 20 ° C. was 94.6 mPa · s. Incidentally, the viscosity at 20 ° C. of a general ink used for a DOD type ink jet printer is relatively low such as about 3 to 6 mPa · s.
In the trial production of ink, it is possible to dissolve all the components that make up the ink in one container and dissolve it all together. However, the dissolution of the dye is concentrated using only part of the dye, resin and solvent. In order to obtain a stable ink, it is preferable to prepare a system in which a blocked isocyanate is added and mixed and dissolved after dissolution.

  The obtained ink has a total of 210 drops (30 drops from 7 nozzles) by a DOD type inkjet printer (product name: HQ, manufactured by Kishu Giken Kogyo Co., Ltd., inkjet head type: KJ1, nozzle diameter = 50 μm) on a silicon wafer. A circular black spot (an example of a printed material) formed by spraying and composed of a plurality of dots was formed. The ink jet head of this DOD ink jet printer is set to 60 ° C. The silicon wafer on which the black spots were formed was heated in an oven at 180 ° C. for 20 minutes. The silicon wafer after the heat treatment was subjected to various physical property tests described in detail below. Moreover, the state of the black spot on the surface of the silicon wafer after the heat treatment is as shown in the photograph of FIG.

[Example 2]
2 parts by weight of butyral resin (molecular weight = 19000, hydroxyl group content = 36%, acetyl group content = 3%, butyralization degree = 63%) was dissolved in 90.5 parts by weight of 2-phenoxyethanol to obtain a solution, To this solution, 2.5 parts by weight of nigrosine base EX (manufactured by Orient Chemical Co., Ltd.) was added, heated to 60 ° C. and mixed with stirring to obtain a mixed solution. After cooling this mixed solution to room temperature, 5 parts by weight of a blocked isocyanate containing dimethylpyrazole as a blocking agent was added and mixed, followed by high-speed stirring and mixing. Thereafter, the mixed solution was filtered through a filter having an opening of 1.0 μm to obtain an ink for an ink jet printer.

[Example 3]
Butyral resin (molecular weight = 21000, hydroxyl group content = 22%, acetyl group content = 3%, butyralization degree 63%) 2.5 parts by weight, Solsperz 24000 (dispersing agent: manufactured by Lubrizol) 0.5 parts by weight Solspers 5000 (dispersing agent: Lubrizol) 0.2 parts by weight and rosin-modified maleic resin 1 part by weight are dissolved in 92.3 parts by weight of 2-phenoxyethanol to form a solution. 2.5 parts by weight of black (REGAL330R: manufactured by Cabot) 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, 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.

[Example 4]
Butyral resin (molecular weight = 19000, hydroxyl group content = 36%, acetyl group content = 3%, butyralization degree 63%) 2.6 parts by weight, Solsperz 24000 (dispersant: manufactured by Lubrizol) 0.6 part by weight Solspers 5000 (dispersant: Lubrizol) 0.1 part by weight and rosin-modified maleic resin 0.6 part by weight are dissolved in 90 parts by weight of 2-phenoxyethanol to obtain a solution, and carbon is added to the solution. 2 parts by weight of black (PRINTEX45: manufactured by Evomic) was added and mixed by stirring, and this mixed solution was subjected to a horizontal sand mill to disperse carbon black. To this dispersion, 3 parts by weight of blocked isocyanate containing dimethylpyrazole as a blocking agent was added and mixed, and high speed stirring and mixing were performed. 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 production of the ink using the pigment as in Examples 3 and 4, it is possible to put all the components constituting the ink in one container and disperse all together, but the pigment, the dispersant, the resin In order to obtain a stable ink, it is preferable to disperse the pigment as a concentrated system using only a part of the solvent, and to add and mix and dissolve the blocked isocyanate after the dispersion.
The inks obtained in Examples 2 to 4 were heated after being printed on a silicon wafer by the DOD type inkjet printer (product name: HQ) manufactured by Kishu Giken Co., Ltd. as described in Example 1. Processed and subjected to various physical property tests detailed below.

[Example 5]
The ink of Example 5 uses a dye in the same manner as in Example 1, and an ink having the composition shown in Table 1 is obtained. In the same manner as in Example 1, the ink was sprayed on the surface of the silicon wafer and evaluated in the same manner .
And the ink of Comparative Examples 1-6 was obtained by the process substantially the same as Examples 1-5 except block isocyanate not being used. These inks of Comparative Examples 1 to 6, in order to clarify the comparison of the effect of the thermal curing of Examples 1 5 and is adjusted to a viscosity of the ink and comparable examples 1-5.
The ink obtained in Example 5 was also heat-treated after being printed on a silicon wafer by the DOD type inkjet printer (product name: HQ) manufactured by Kishu Giken Co., Ltd. as described in Example 1. The samples were subjected to various physical property tests described in detail below.

The formulations and physical property test results of the inks of Examples 1 to 5 are shown in Table 1 below. The formulations and physical property test results of the inks of Comparative Examples 1 to 6 are shown in Table 2 below. The outline of the physical property test shown in each table is explained below.
[Viscosity] is measured at 60 ° C. by an EH viscometer.
[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. A film with good surface condition and good fluidity at the time of dispersion was evaluated as “◯”, a film that did not disperse was evaluated as “x”, and an agglomerated film was “aggregated”. It was determined whether or not the ink containing the dye was “dissolved”.

[Ejection stability] is achieved by printing the ink shown in each example on the surface of a glass substrate with a DOD ink jet printer (product name HQ-KJ1, manufactured by Kishu Giken Kogyo Co., Ltd., nozzle diameter = 50 μm). The state of was visually evaluated. In addition, the ejection characteristics of the nozzles during continuous printing were also evaluated by observing the state of the obtained print. Each print dot that has been printed continuously and accurately at a predetermined position is evaluated as “◯”, and even though continuous printing has been performed, a missing dot occurs in the middle, or each print dot is printed at a predetermined position. Those that were not made were marked as “x”.
[Resolubility] means that the ink is applied to the nozzle plate of the continuous ink jet printer and air-dried, and the next day, another ink is sprinkled on the dry ink, and the dissolution of the dry ink is confirmed. Those having good solubility were evaluated as “◯”, and those having poor solubility were evaluated as “x”.
[Storage stability] is that the ink was sealed in a sealed container and stored at 45 ° C., and the appearance and viscosity change of the ink were confirmed after two months. Those in which the appearance and viscosity did not change to a predetermined value or more (an increase in viscosity of 8% or more) were evaluated as “◯”, and those in which the appearance and viscosity changed to a predetermined value or more were rated “X”.

[Thermosetting] is a condition in which a printed printed body is cured by heat, such as curability at 150 ° C. for 30 minutes, curability at 170 ° C. for 30 minutes, and curability at 200 ° C. for 15 minutes. Each has been confirmed. This thermosetting property is confirmed by whether or not ethanol is applied to the cured surface cured by heat and the thermally cured printing body is dissolved. Those that did not dissolve were evaluated as “◯”, and those that partially dissolved were evaluated as “x”.
[Alcohol resistance] means that the surface of the printed material after the printed body is thermally cured is rubbed 10 times with a cotton swab soaked in ethanol, and dissolution and peeling of the printed dots on the surface of the printed material are confirmed. . The case where there was no peeling was evaluated as “◯”, and the case where there was peeling was “x”.
[Washability] is whether the printed material is immersed in a 0.25% nonionic activator aqueous solution, subjected to a cleaning test by ultrasonic irradiation for 15 minutes, and the printed mark is read by a reader. No is evaluated. Those having no reading abnormality were evaluated as “◯”, and those having reading abnormality were evaluated as “X”.
[Adhesion] was evaluated whether or not the printed dots (printed body) were peeled off when the cellophane tape was applied to the surface of the printed substrate and the cellophane tape was peeled off. It is. The case where there was no peeling of the printed dot print was evaluated as “◯”, and the case where there was peeling was set as “x”.
In each table, all the numerical values shown in the prescription column represent weight% with respect to the total weight of the ink.

In the inks obtained in Examples 1 to 5 described above, the results of any of the above physical property tests were poor after printing on the surface of the printing material and before the heat treatment. However, as shown in Table 1, since these contain butyral resin, rosin-modified maleic acid resin, blocked isocyanate, and phenoxyethanol, which is the main solvent, in suitable proportions, they have good characteristics after heat treatment. showed that. At the same time, the storage stability and the long-term printing stability in the printer also show good characteristics. As described above, the ink according to Examples 1 to 5 is a specific usage mode in which a thermosetting ink is used in a place where heat is applied such as 60 ° C. during processing by a semiconductor inspection apparatus or the like. It can be seen that it exhibits excellent characteristics without hindrance.

  As shown in the photograph of FIG. 1, the dot (black dot) B1 printed on the surface of the silicon wafer S using the ink of Example 1 and cured by heat treatment is formed into a correct circle having a diameter of about 1.5 mm. Has been. That is, it was possible to form one dot B1 having a size that can be easily recognized. Accordingly, the presence / absence of marking can be accurately and reliably determined by either visual inspection or optical determination means. Note that numerical values such as 1, 2, and 3 displayed in the photograph of FIG. 1 are attached for measuring the profile and do not represent the length. The numerical values displayed in the photograph of FIG. 2 described later are also the same.

  On the other hand, as shown in Table 2, the inks of Comparative Examples 1 to 6 have poor ethanol resistance because no blocked isocyanate is used and, of course, no thermosetting treatment is performed. Since it did not occur, the ethanol resistance was poor.

  On the other hand, FIG. 2 shows an inkjet in which a general low-viscosity ink (4 mPa · s at 25 ° C.) commonly used for DOD-type inkjet printers is set at room temperature in order to form a correct circular dot. A photograph showing what was printed by being sprayed on the surface of the silicon wafer S by the head in the same manner as in Example 1 is shown. As is apparent from the photograph of FIG. 2, four divided dots B2, B2, B2, and B2 were formed. Of these, the three small dots B2, B2, B2 have a diameter of about 0.5 mm. That is, one dot having a size that can be easily recognized is not formed. In such a divided dot printing form, the shape and size of the markings are non-uniform, making it difficult to identify.

In addition, since none of the inks of Examples 1 to 5 described above uses a chlorine-containing resin typified by vinyl chloride / vinyl acetate copolymer resin, a silicon wafer is used even when used in a semiconductor inspection apparatus. No harmful chlorine gas is generated.

B1, B2 dot S silicon wafer (example of semiconductor wafer)

Claims (3)

An inkjet ink comprising a colorant, a solvent having a boiling point of 120 ° C. or higher, a resin, and a blocked isocyanate , and having an ink viscosity at 60 ° C. of 8 mPa · s to 15 mPa · s ,
The blocking agent incorporated in the blocked isocyanate is dimethylpyrazole, the resin is a butyral resin, or a butyral resin and a rosin-modified maleic acid resin, and the solvent is mainly composed of 2-phenoxyethanol. An ink-jet ink comprising: Of total ink weight, 1 to 10% by weight of the colorant, the resin 0.3 to 20 wt%, a blocked isocyanate 0.1-7 wt%, respectively contained, in claim 1 the balance being solvent The ink for inkjet described. A printing step of forming a printed body by spraying ink droplets of the ink jet ink according to claim 1 or 2 onto a surface of a semiconductor wafer using a drop-on-demand ink jet printer, and the surface of the semiconductor wafer And a heating step of heating the printed body in a temperature atmosphere of 180 ° C. or higher and 250 ° C. or lower for more than 10 minutes and not more than 60 minutes.