Non-aqueous inkjet ink composition

Abstract

To provide an ink composition for inkjet which has excellent ejection stability and drying properties even in the case where printing is performed by an ink composition for inkjet onto a substrate to be printed whose printing surface is made of resin or the like, and furthermore, is capable of, even in the case of using a resin substrate on a part of which printing is already done as an object to be printed, performing printing on a condition of no influence by heat to the substrate to be printed or an already formed printed part, and a printing method thereof.SOLUTION: A non-aqueous ink composition for inkjet for resin substrate printing contains carbon black by 2.5 to 10.0 mass%, contains organic solvent having an evaporation rate of 20 to 80 when the evaporation rate of butyl acetate is 100 by 80.0 mass% or more, contains resin, and has drying properties by infrared irradiation.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a non-aqueous inkjet ink composition for use on the surface of a substrate made of resin or the surface of a print portion already formed on the surface of any material. [Background technology]

[0002] As described in Patent Document 1, a non-aqueous inkjet ink composition containing a pigment, a resin, a dispersant, and an organic solvent, in which the printing substrate is a resin, is known. However, with these non-aqueous ink jet ink compositions, the organic solvent quickly evaporates immediately after printing, allowing the ink to dry and print the desired image or the like.

[0003] However, because such non-aqueous ink jet printing ink compositions have good drying properties, when ejection is stopped after continuous ejection and then resumed, nozzle clogs, i.e., nozzles that are unable to eject the non-aqueous ink jet printing ink composition, may occur, making it necessary to perform operations such as cleaning, or to switch to a non-aqueous ink jet printing ink composition that dries more slowly. If cleaning or other operations are required, this will cause a decrease in productivity of printed materials. Furthermore, if a change is made to a non-aqueous inkjet printing ink composition that does not dry quickly, there is a concern that when printed materials are placed one on top of the other, the ink composition of the lower printed layer will be transferred to the back side of the printed material above it, resulting in show-through.

[0004] A method of heating and drying an inkjet ink composition immediately after printing is known, in which the inkjet ink composition is aqueous or contains water, and printing is performed by heating and evaporating the water. Such a printing method of heat drying can be used exclusively when paper is used as the printing substrate. When a resin is used as the printing substrate, even if printing is performed on only a portion of the printing substrate, the heat drying device is designed to heat the entire surface of the printing substrate, so that at least a portion of the resin printing substrate will be deformed or wrinkled due to heat. Furthermore, when attempting to dry by irradiating infrared rays, and when printing and drying are performed successively to quickly obtain multiple printed items, it has been necessary to increase the intensity of infrared irradiation. As a result, although the printed ink composition can be dried, the printing substrate is also heated at the same time, and the heating temperature can become too high, which can cause damage such as deformation or wrinkling to the printing substrate and the already formed printed areas. Furthermore, when a second print is performed on the printed and / or non-printed portions of a printed substrate that has already had a first print applied to a portion thereof, if the second print involves heat drying, the printed substrate and the printed portions from the first print may be damaged by heat, such as by wrinkling or deformation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-59106 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide an inkjet ink composition that exhibits excellent ejection stability and drying properties even when the inkjet ink composition is used to print on a substrate having a printing surface made of resin or the like, and that can be printed on a resin substrate that has already been partially printed, under conditions that do not affect the substrate or the already formed printed portion due to heat, and a printing method using the inkjet ink composition. [Means for solving the problem]

[0007] As a result of extensive research into solving the above problems, the present inventors have found that the above problems can be solved by using an organic solvent with a specific composition, and have thus completed the present invention. That is, the present invention provides: 1. a composition containing 2.5 to 10.0 mass % of carbon black; The solvent contains 80.0% by mass or more of an organic solvent having an evaporation rate of 20 to 80, where the evaporation rate of butyl acetate is 100, Contains resin, Drying by infrared irradiation, A non-aqueous inkjet ink composition for printing on resinous substrates. 2. The non-aqueous inkjet ink composition according to 1, which is used for printing on a printing layer provided on a resin substrate. 3. The non-aqueous inkjet ink composition according to 1 or 2, wherein the resin contained in the non-aqueous inkjet ink composition comprises at least one selected from the group consisting of acrylic resins, cellulose resins, and vinyl chloride-vinyl acetate resins. 4. The non-aqueous inkjet ink composition according to any one of claims 1 to 3, which contains 80.0% by mass or more of an organic solvent having an evaporation rate of 30 to 60, where the evaporation rate of butyl acetate is taken as 100. 5. Contains 2.5 to 10.0 mass% carbon black, The solvent contains 80.0% by mass or more of an organic solvent having an evaporation rate of 20 to 80, where the evaporation rate of butyl acetate is taken as 100, A non-aqueous inkjet ink composition containing a resin is used. Inkjet printing is performed on a printing substrate made of resin and / or a printing portion previously formed on the surface of the printing substrate, Drying is carried out by infrared irradiation. A method of printing with a non-aqueous ink jet ink composition. [Effects of the Invention]

[0008] The non-aqueous inkjet ink composition of the present invention contains an acrylic resin, a pigment, a pigment dispersant, and an organic solvent having a specific composition. As a result, the heat-drying ink composition for printing on a resin substrate has excellent drying properties and good ejection stability from the nozzle of an inkjet printer, and can be printed under conditions that do not damage the resin substrate or the printed portion that has already been formed. DETAILED DESCRIPTION OF THE INVENTION

[0009] (carbon black) The carbon black used in the present invention may be any carbon black used in inks. If the non-aqueous inkjet ink composition contains only black colorants other than carbon black, such as lactam black, perylene black, solvent blacks such as Solvent Black 29, various disperse blacks, direct blacks, and acid blacks, it is difficult to sufficiently heat-dry the ink. Among black colorants that can generate heat by absorbing infrared rays, especially near-infrared rays, carbon black is required. Carbon black can be used alone or in combination of two or more types. The amount used is 2.5% by mass or more and 10% by mass or less, based on the total amount of the non-aqueous inkjet ink composition. 3.0% by mass or more is more preferable. 9.0% by mass or less is also preferable, 8.5% by mass or less is more preferable, 8.0% by mass or less is even more preferable, and 5.0% by mass or less is most preferable. If the amount is less than 2.5% by mass, the energy of the infrared rays irradiated must be excessively high to dry the printed non-aqueous inkjet ink composition. This can cause the temperature of the resin substrate (the printing substrate) to rise too high, potentially causing wrinkles, distortions, or deformations on the surface of the resin substrate, resulting in damage. If the energy of the infrared rays irradiated is reduced to prevent such damage, the drying properties of the ink composition will decrease. On the other hand, if the amount is greater than 10.0% by mass, the viscosity will increase, reducing the ejection stability of the non-aqueous inkjet ink composition. Furthermore, even if infrared rays are irradiated at higher energy levels, further improvement in drying properties cannot be expected.

[0010] (Coloring materials other than carbon black) As coloring materials other than carbon black contained in the non-aqueous inkjet ink composition of the present invention, known inorganic and organic pigments and dyes that have conventionally been used in non-aqueous inkjet ink compositions, black coloring materials other than carbon black, and the like can be used, as long as the effects of the present invention are not impaired. Specific examples of the inorganic pigment include titanium oxide, zinc oxide, zinc oxide, tripon, iron oxide, aluminum oxide, silicon dioxide, kaolinite, montmorillonite, talc, barium sulfate, calcium carbonate, silica, alumina, cadmium red, red iron oxide, molybdenum red, chrome vermilion, molybdate orange, yellow lead, chrome yellow, cadmium yellow, yellow iron oxide, titanium yellow, chromium oxide, pyridian, cobalt green, titanium cobalt green, cobalt chrome green, ultramarine blue, Prussian blue, cobalt blue, cerulean blue, manganese violet, cobalt violet, and mica. Specific examples of organic pigments include azo, azomethine, polyazo, phthalocyanine, quinacridone, anthraquinone, indigo, thioindigo, quinophthalone, benzimidazolone, isoindoline, and isoindolinone organic pigments. Specific examples of organic pigments are listed in the color index: Pigment Black 7, Pigment Blue 15, 15:1, 15:3, 15:4, 15:6, and 60; Pigment Green 7, 36; and Pigment Red 9, 48, 49, 52, 53, 57, 97, 122, and 14. 9, 168, 177, 178, 179, 206, 207, 209, 242, 254, 255, Pigment Violet 19, 23, 29, 30, 37, 40, 50, Pigment Yellow 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 94, 95, 109, 110, 117, 120, 125, 128, 137, 138, 139, 147, 148, 150, 151, 154, 155, 166, 168, 180, 185, Pigment Orange 36, 43, 51, 55, 59, 61, 71, 74, etc. The metal pigment may or may not be contained. Specific examples of the dye include various known dyes such as anionic dyes, cationic dyes, nonionic dyes, and zwitterionic dyes.

[0011] (resin) The non-aqueous inkjet ink composition of the present invention contains a resin. The resin that can be contained must be sufficiently soluble in the solvent of the present invention and be able to form a film after printing. The non-aqueous inkjet ink composition of the present invention dries by heating to form a film on the printed area, but does not contain a resin whose reactive components react to form a resin film when heated. The resin that can be used is preferably one or more selected from acrylic resins, cellulose resins, vinyl chloride-vinyl acetate resins, and the like. The resin content of the non-aqueous inkjet ink composition is preferably 1.0% by mass or more, more preferably 3.0% by mass or more, and even more preferably 5.0% by mass or more, and is preferably 20.0% by mass or less, more preferably 15.0% by mass or less, and even more preferably 12.0% by mass or less, based on the total amount of the non-aqueous inkjet ink composition. If the resin content is less than 1.0% by mass, the adhesion to the substrate may be insufficient, making it difficult to reliably form a printed layer. If the resin content is more than 20.0% by mass, it may be difficult to perform printing with excellent ejection stability.

[0012] (acrylic resin) Examples of acrylic resins that may be contained in the non-aqueous inkjet ink composition of the present invention include polymers and copolymers of (meth)acrylates soluble in organic solvents. Examples of such (meth)acrylates include alkyl (meth)acrylates such as ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate; and hydroxyalkyl (meth)acrylates such as hydroxymethyl, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, and hydroxypentyl (meth)acrylate. Examples include Mitsubishi Rayon's Dianarl series BR-60 (Tg: 75 ° C), BR-64 (Tg: 55 ° C), BR-75 (Tg: 90 ° C), BR-77 (Tg: 80 ° C), BR-83 (Tg: 105 ° C), BR-87 (Tg: 105 ° C), BR-88 (Tg: 105 ° C), BR-90 (Tg: 65 ° C), BR-93 (Tg: 50 ° C), BR-95 (Tg: 80 ° C), BR-105 (Tg: 50 ° C), BR-106 (Tg: 50 ° C), BR-107 (Tg: 50 ° C), BR-108 (Tg: 90 ° C), BR-113 (Tg: 75 ° C), BR-115 (Tg: 50 ° C) and BR-116 (Tg: 50 ° C).

[0013] (cellulose-based resin) Examples of cellulose-based resins that may be contained in the non-aqueous inkjet ink composition of the present invention include lower acyl-substituted cellulose resins such as nitrocellulose (nitro group-substituted), cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate, and lower alkyl-substituted cellulose resins such as methylcellulose and ethylcellulose.

[0014] (Vinyl chloride-vinyl acetate resin) The vinyl chloride-vinyl acetate resin that may be used in the present invention is basically a vinyl chloride-vinyl acetate copolymer containing vinyl chloride and vinyl acetate as essential components, and is obtained by copolymerizing it with other radically polymerizable monomers added as necessary. In this copolymerization, the ester bond at the vinyl acetate-derived site is saponified, and an amino group-containing compound is used as the other radically polymerizable monomer, or an amino group-containing hydrocarbon compound is used to dehydrochlorinate the vinyl chloride-derived site to introduce an amino group. For example, an amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer can also be used.

[0015] As such a vinyl chloride-vinyl acetate resin, a copolymer of vinyl chloride monomer and vinyl acetate monomer, which has been used conventionally in ink compositions, can be used. Specific examples include SOLBIN C, SOLBIN CL, SOLBIN CH, SOLBIN CN, SOLBIN C5R, SOLBIN A, SOLBIN AL, SOLBIN TA2, SOLBIN TA3, SOLBIN TAO, SOLBIN TA5R, SOLBIN M, SOLBIN ME, SOLBIN MFK (all manufactured by Nissin Chemical Industry Co., Ltd.), VINNOL E15 / 48A, VINNOL E22 / 48A, VINNOL E14 / 45, VINNOL H14 / 36, VINNOL H40 / 55, VINNOL E15 / 45M (all manufactured by WACKER), and the like. As the vinyl chloride-vinyl acetate resin, it is preferable to use a vinyl chloride-vinyl acetate resin containing 85% vinyl chloride and 15% vinyl acetate. In particular, in the case of vinyl chloride-vinyl acetate copolymers having hydroxyl groups obtained by saponifying a portion of the acetate ester moieties, the film properties and dissolution behavior of the resin are determined by the ratio of structural units based on the reactive sites of vinyl chloride in the molecule (formula 1 below), structural units based on the reactive sites of vinyl acetate (formula 2 below), and structural units based on saponification of the reactive sites of vinyl acetate (formula 3 below). That is, the structural units based on the vinyl chloride reactive sites impart toughness and hardness to the resin film, the structural units based on the vinyl acetate reactive sites impart adhesiveness and flexibility, and the structural units based on the saponification of the vinyl acetate reactive sites impart good solubility to the organic solvent system of the environmentally friendly ink. Formula 1 -CH2-CHCl- Formula 2 -CH2-CH(OCOCH3)- Formula 3 -CH2-CH(OH)-

[0016] (Amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol resin) The amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol resin that may be used in the present invention is composed of vinyl chloride units, vinyl acetate units, vinyl alcohol units, and amino group-containing units. Vinyl chloride units and vinyl acetate units refer to units that are formed by the cleavage of unsaturated double bonds in the copolymer after the reaction of vinyl chloride and vinyl acetate, respectively, and are composed of ethylene chains formed by the cleavage of unsaturated double bonds and the residues of the monomers bonded to the ethylene chains, excluding the unsaturated double bonds. Specifically, a vinyl chloride unit is a unit represented by [-CH2-CHCl-], and a vinyl acetate unit is a unit represented by [-CH2-CH(OCOCH3)-]. A vinyl alcohol unit is a unit formed by the ethylene chain and the hydroxyl group bonded to the ethylene chain after the ester bond of the vinyl acetate unit is hydrolyzed by a saponification reaction, and is represented by [-CH2-CH(OH)-]. Furthermore, when a compound containing an amino group is used as the other radically polymerizable monomer, the amino group-containing unit is a unit composed of an ethylene chain generated by cleavage of the radically polymerizable unsaturated double bond and the residue of the monomer bound to it excluding the unsaturated double bond, and is represented by [-CH2-CHX-] (X is a residue excluding the unsaturated double bond of the monomer and contains an amino group).On the other hand, when an amino group-containing hydrocarbon compound is introduced into a vinyl chloride unit by dehydrochlorination, the amino group-containing unit is a unit in which the chlorine in the vinyl chloride unit is replaced by a residue of the amino group-containing hydrocarbon compound from which one hydrogen has been removed, and is represented by [-CH2-CHY-] (Y is a residue of the amino group-containing hydrocarbon compound from which one hydrogen has been removed).

[0017] The amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer can be produced, for example, by obtaining a copolymer of vinyl chloride, vinyl acetate, and a monomer having an amino group-containing ethylenically unsaturated double bond, and then saponifying the copolymer to convert some of the vinyl acetate units into vinyl alcohol units to form amino group-containing units. The amino group-containing ethylenically unsaturated double bond monomer can be a monomer represented by the general formula (1): [ka] In the formula, R1 is a hydrogen atom or a methyl group, R2 and R3 are independently a monovalent hydrocarbon group, and m is an integer of 1 to 6. Examples of (meth)acrylic acid dialkylaminoalkyl esters represented by the formula (CH2)m in the general formula (1) include a methylene group, an ethylene group, a trimethylene group, a propylene group, a tetramethylene group, and a butylene group. Examples of the monovalent hydrocarbon groups represented by R2 and R3 include alkyl groups having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group. Specific examples of the amino group-containing ethylenically unsaturated double bond monomer represented by the general formula (1) include dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, and diethylaminopropyl (meth)acrylate. As the amino group-containing ethylenically unsaturated double bond monomer, in addition to the monomer represented by the general formula (1), dimethylaminopropylacrylamide, dimethylacrylamide, acrylamide, etc. can also be used.

[0018] Another method for producing the amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer is to treat the vinyl chloride-vinyl acetate copolymer in the presence of an amine compound by saponification / amine modification, converting some of the vinyl acetate units into vinyl alcohol units, and reacting some of the chlorine atoms in the vinyl chloride units with the amine compound to introduce amino groups into the side chains to form amino group-containing units. Examples of the amine compound include aliphatic amines, alicyclic amines, and aromatic amines. Specific examples include ethylamine, propylamine, butylamine, cyclohexylamine, ethanolamine, naphthylamine, aniline, o-toluidine, diethylamine, dibutylamine, diisobutylamine, dioctylamine, diethanolamine, N-methylaniline, trimethylamine, triethylamine, tributylamine, triisobutylamine, N-methyldiphenylamine, and triethanolamine.

[0019] From the viewpoint of ink ejection stability and adhesion to the recording medium, it is preferable to use an amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer in which the proportion of vinyl alcohol units in the copolymer is 4.0 to 7.0% by mass. If the proportion of vinyl alcohol units in the copolymer is less than 4.0% by mass, adhesion tends to decrease, while if it exceeds 7.0% by mass, ejection stability tends to decrease. In addition, the amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer preferably contains amino group-containing vinyl chloride units and vinyl acetate units in a mass ratio of amino group-containing vinyl chloride units / vinyl acetate units of 80 / 20 to 99 / 1.

[0020] Furthermore, the content of the amino group-containing unit in the amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer is preferably 0.1 to 5.0% by mass in the copolymer. If the proportion of the amino group-containing unit is less than 0.1% by mass, the ejection stability tends to decrease.

[0021] The amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer preferably has a number average molecular weight in the range of 10,000 to 50,000. If the number average molecular weight exceeds this range, the viscosity increases, making it difficult to eject the copolymer from a nozzle. Commercially available amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymers include SOLBIN TAO and SOLBIN TAOL (both manufactured by Nissin Chemical Industry Co., Ltd.).

[0022] It is also possible to use in combination with resins other than the above-mentioned acrylic resins, cellulose resins, and vinyl chloride-vinyl acetate resins, such as vinyl chloride resins, vinyl chloride-acrylic resins, ethylene-vinyl acetate resins, styrene-acrylic resins, styrene-maleic acid resins, rosin resins, rosin ester resins, petroleum resins, coumarone-indene resins, terpene-phenol resins, phenol resins, urethane resins, melamine resins, urea resins, epoxy resins, xylene resins, alkyd resins, aliphatic hydrocarbon resins, butyral resins, maleic acid resins, and fumaric acid resins, within the scope that does not impair the effects of the present invention. In particular, when a vinyl chloride-vinyl acetate resin is used in combination, the vinyl chloride-vinyl acetate resin can be blended in an amount of preferably 1.0 to 15.0 parts by mass, more preferably 2.0 to 12.0 parts by mass, and even more preferably 3.0 to 10.0 parts by mass per 100 parts by mass of the acrylic resin or vinyl chloride-vinyl acetate resin. The ink composition of the present invention has drying properties when irradiated with specific energy rays, and does not contain a polymerizable monomer.

[0023] (pigment dispersant) As the pigment dispersant that may be contained in the non-aqueous inkjet ink composition of the present invention, an ionic or nonionic surfactant, or an anionic, cationic or nonionic polymer compound, etc. may be used. Among these, polymeric compounds are preferred, such as the carbodiimide compounds described in JP 2004-083872 A, WO 2003 / 076527 A, and WO 2004 / 000950 A, basic functional group-containing copolymers AJISPER PB821 and PB822 (both manufactured by Ajinomoto Fine Chemicals Co., Ltd.) (acid value and amine value both 10 to 20 mgKOH / g), Solsperse 56000, Solsperse 32000, Solsperse 39000 (all manufactured by Lubrizol Corporation), and the DISPERBYK series (BYK-Chemie). These pigment dispersants can be used alone or in combination of two or more. Among these, a basic functional group-containing copolymer having an amine value of 10.0 to 40.0 mgKOH / g is preferred. The pigment dispersant is appropriately selected and used depending on the type of pigment and the type of organic solvent used.

[0024] (organic solvent) In the present invention, an organic solvent having an evaporation rate of 20 to 80, where the evaporation rate of butyl acetate is taken as 100, is obtained by the measurement method described in ASTM D3539-87, and is an evaporation rate value calculated by the following formula by measuring the evaporation time of n-butyl acetate and the evaporation time of the test solvent at 25°C in dry air. {(Time required for 90% by mass of n-butyl acetate to evaporate) / (Time required for 90% by mass of the test solvent to evaporate)} x 100 The organic solvent having an evaporation rate of 20 to 80, where the evaporation rate of butyl acetate is taken as 100, is contained in the non-aqueous inkjet ink composition so as to be 80.0% by mass or more. It is preferably 82.0% by mass or more, and more preferably 84.0% by mass or more. It is also preferably 93.0% by mass or less, and more preferably 90.0% by mass or less. If it is less than 80.0% by mass, a higher heating temperature or longer heating time is required in the drying step, which may deteriorate the underlying printed layer.

[0025] The evaporation rate of each organic solvent contained in the non-aqueous inkjet ink composition of the present invention is preferably 75 or less, more preferably 70 or less, and even more preferably 50 or less, when the evaporation rate of butyl acetate is taken as 100. It is also preferably 25 or more, and more preferably 30 or more. In particular, the non-aqueous inkjet ink composition of the present invention preferably contains a solvent whose evaporation rate is 25 or more, when the evaporation rate of butyl acetate is taken as 100, and preferably contains only solvents whose evaporation rate is 25 or more, when the evaporation rate of butyl acetate is taken as 100. Preferred organic solvents include propylene glycol monomethyl ether acetate (evaporation rate 44), ethyl lactate (evaporation rate 22), propylene glycol monomethyl ether (evaporation rate 71), xylene (evaporation rate 68), tripropylamine (evaporation rate 20), mesitylene (evaporation rate 22), dibutyl ether (evaporation rate 43), nonane (evaporation rate 39), mesitylene (evaporation rate 22), isobutyl alcohol (evaporation rate 64), 1-butanol (evaporation rate 47), ethylene glycol monomethyl ether (evaporation rate 53), ethylene glycol monoethyl ether (evaporation rate 38), 1-ethoxy-2-propanol (evaporation rate 34), and propylene glycol monopropyl ether (evaporation rate 22).

[0026] Other known organic solvents having an evaporation rate of less than 20 or more than 80 can be used in combination as long as the effect of the present invention is not impaired, but such other known organic solvents do not have to be used in combination. Furthermore, it may or may not contain alkylene glycol dialkyl ethers such as diethylene glycol diethyl ether, ethylene glycol monobenzyl ether, ethylene glycol monophenyl ether, 3-methoxybutanol, ethylene glycol monobutyl ether acetate, or ethylene glycol diacetate.

[0027] (Other ingredients) Furthermore, various additives such as surfactants, plasticizers, surface conditioners, ultraviolet protection agents, light stabilizers, and antioxidants may be used in the non-aqueous inkjet ink composition of the present invention, if necessary.

[0028] (Production of non-aqueous inkjet ink composition) Next, a method for producing the non-aqueous inkjet ink composition of the present invention using these materials will be described. The non-aqueous inkjet ink composition of the present invention can be obtained by dispersing and mixing using a dispersing machine such as a wet circulation mill, a bead mill, a ball mill, a sand mill, an attritor, a roll mill, a DCP mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a high-pressure homogenizer (such as a Microfluidizer, Nanomizer, Ultimizer, Genus PY, or DeBEE2000), or a pearl mill, and adjusting the viscosity of the non-aqueous inkjet ink composition to 2.0 to 10.0 mPa s. The total organic solvent content in the non-aqueous inkjet ink composition of the present invention is the amount obtained by subtracting the total amount of the resin, pigment, pigment dispersant, and other additives used as needed from the total amount of the ink composition, and it is preferable to change this amount appropriately so that the ink viscosity falls within the above-mentioned range. The nonaqueous inkjet ink composition of the present invention obtained in this manner is printed using a known inkjet printer. The printing substrate may be one on which a printed layer has been previously printed, or a substrate on which no printed layer has been previously formed. Among these, the nonaqueous inkjet ink composition can be used particularly when the substrate or the previously formed printed layer is prone to softening and shrinking upon heating.

[0029] (Application) The non-aqueous inkjet ink composition of the present invention can be used in well-known applications in which a resin substrate is used as the printing surface, and can also be used in applications in which the surface of a printing portion pre-formed on the surface of a substrate made of any material is used as the printing surface.

[0030] (Printing method) After printing using the non-aqueous inkjet ink composition of the present invention using a known inkjet printer as described above, the printed material can be quickly dried and solidified by irradiating it with infrared rays. The substrate to be printed may be resin, paper, or metal. However, the substrate may be made of a material that is prone to wrinkling or deformation due to excessive heating. Resin substrates are preferred, with thermoplastic resin substrates being more preferred. When a resin substrate is used, known resins such as polyolefin resins, polyvinyl chloride resins, polyvinyl alcohol resins, acrylic resins, polyester resins, and polyamide resins can be used. The irradiated infrared rays are absorbed by the carbon black contained in the non-aqueous inkjet ink composition of the present invention, allowing the energy of the irradiated infrared rays to be used efficiently for heating. If a colorant other than carbon black were used, the irradiated infrared energy would need to be significantly higher, increasing the possibility of excessively raising the temperature of the resin substrate being the substrate to be printed. The infrared rays used in this case may have a peak at 0.90 to 1.25 μm, and within this range, the wavelength is preferably 1.00 μm or more, more preferably 1.05 μm or more, more preferably 1.20 μm or less, and even more preferably 1.15 μm or less. The infrared radiation exposure time is preferably within a range that allows the printed non-aqueous inkjet ink composition to dry and solidify without excessively slowing the drying speed relative to the printing speed of the inkjet printer. To ensure drying and curing within this range of exposure time, the infrared radiation output is preferably 2.0 kW or more. It is preferable to position the infrared light source as close as possible to the surface of the printed non-aqueous inkjet ink composition, and the distance is about 1.0 to 15.0 mm, and within this range, it may be 2.0 mm or more, 3.0 mm or more, 12.0 mm or less, or 10.0 mm or less. If the intensity of the irradiated infrared rays is too strong, the temperature of the surface of the printing substrate may become excessively high when the printing substrate is made of resin, which may cause damage to the surface of the printing substrate, such as wrinkles, distortions, and bending. [Example]

[0031] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass." The materials used in the following Examples and Comparative Examples are as follows: All components other than the organic solvent are in solid content. The units of values ​​in the columns for each component and total in the table are "mass %." <Carbon black> Bk7: Carbon black MA7 (Mitsubishi Chemical Corporation) <Black dye> Solvent Black 29: Orazol Black RLI (BASF) <Pigment dispersant> Solsperse 32000 (Lubrizol) <Resin> Dianall BR-83: Acrylic resin (Mitsubishi Rayon Co., Ltd.) SOLBIN TAO: Amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer (Nissin Chemical Industry Co., Ltd.)

[0032] (Examples 1 to 5, Comparative Examples 1 to 5, Reference Examples 1 to 4) <Production of non-aqueous inkjet ink composition> The materials were mixed and stirred according to the formulations in Tables 1 and 2 (the blending ratio of each material is % by mass) to obtain non-aqueous inkjet ink compositions for each Example, Comparative Example, and Reference Example.

[0033] <Printing method> A commercially available inkjet printer was loaded with the nonaqueous inkjet ink composition of each Example, Comparative Example, and Reference Example, and a solid print was performed on a stretched polypropylene film (product name P-2161, thickness 25 μm, Toyobo Co., Ltd.) in high-speed printing mode. The printed area was irradiated with infrared light having a peak at 1.10 μm and an output of 2.3 to 7.5 kW from a distance of 10 mm for 0.1 second to dry and cure the ink, yielding a printed material for each Example, Comparative Example, and Reference Example. The following characteristics were measured and evaluated for these printed materials. Evaluation of damage to the substrate was carried out in two cases: when printing was performed without any pre-printed data, and when printing was performed with pre-printed data.

[0034] <Discharge stability> Using a commercially available inkjet printer, solid printing was performed in high-speed printing mode using the ink compositions of each Example, Comparative Example, and Reference Example, and then the printer was left for 1 minute without ejection, and then ejection was resumed, and the number of missing nozzles was measured. ○: All nozzles discharge ×: One or more nozzles missing

[0035] <Drying> A cotton swab is held vertically against the printed matter created using the above method and rubbed in one direction, and the presence or absence of ink adhering to the cotton swab is determined. ○: No ink adhesion ×: Ink adhesion

[0036] <Damage to substrate (no printed data)> The change in appearance of the evaluation piece prepared by the above method is visually judged. ○: No change ×: Changes such as holes, wrinkles, and surface distortion are observed

[0037] <Damage to substrate (printed data included)> A solid image was formed by gravure printing using a surface printing gravure ink (Sapiria Black Ink, Sakata Inks) under the following conditions on the front half of an A4-sized substrate film (product name P-2161, thickness 25 μm, Toyobo Co., Ltd.) in the direction of travel. Next, the non-aqueous inkjet ink compositions of each Example, Comparative Example, and Reference Example were printed and dried under the same conditions on the remaining half of the area, and the appearance of the evaluation pieces thus produced was visually evaluated. ○: No change ×: Changes such as holes, wrinkles, and surface distortion are observed

[0038] (Gravure printing conditions) Base film: Stretched polypropylene film (product name P-2161, thickness 25 μm, Toyobo Co., Ltd.) Printing machine: Gravure proofing machine Ink printing plate: Helio 175ine / inch (pattern: solid printing plate) Printing speed: 80m / min Drying conditions: 80℃

[0039] [Table 1]

[0040] [Table 2]

[0041] According to each example, excellent effects can be achieved, such as excellent ejection stability and drying properties of the non-aqueous inkjet ink composition, and no damage to the substrate. In particular, even when printing on a substrate already having a printed layer formed with a black ink composition containing carbon black and having printed data, the effect was achieved that printing can be performed under conditions that do not cause any change in appearance to the printed portion of the already printed data. However, Comparative Example 1, which had a low carbon black concentration, exhibited poor drying properties, and Comparative Example 2, which had a high carbon black concentration, exhibited poor ejection stability. Furthermore, Comparative Examples 3 and 4, which did not use the organic solvent of the present invention, exhibited poor drying properties or ejection stability. Furthermore, Comparative Example 5, which used a black coloring material other than carbon black, exhibited poor drying properties. In Comparative Examples 1 and 3, which had poor drying properties, when infrared irradiation was continued until drying was complete, wrinkles and the like occurred in the printed base film due to heat. Furthermore, in Reference Examples 1 to 4, which employed the same substrate film as in the Examples but used a non-black pigment, the drying properties were poor in Reference Examples 1 to 4, in which the infrared irradiation intensity was changed. In addition, in Reference Examples 3 and 4, in which the infrared irradiation intensity was high, the damage to the substrate was significant and wrinkles were formed on the substrate surface, even though the infrared irradiation intensity was not strong enough to allow sufficient drying.

Claims

1. Contains 2.5 to 10.0 mass% carbon black, The solvent contains 80.0% by mass or more of an organic solvent having an evaporation rate of 20 to 80% when the evaporation rate of butyl acetate is taken as 100, Contains resin, Drying by infrared irradiation, A non-aqueous inkjet ink composition for printing on resinous substrates.

2. The non-aqueous inkjet ink composition according to claim 1, which is used for printing on a printing layer provided on a resin substrate.

3. 3. The non-aqueous inkjet ink composition according to claim 1, wherein the resin contained in the non-aqueous inkjet ink composition comprises at least one resin selected from the group consisting of an acrylic resin, a cellulose resin, and a vinyl chloride-vinyl acetate resin.

4. 3. The non-aqueous inkjet ink composition according to claim 1, wherein the non-aqueous inkjet ink composition contains 80.0% by mass or more of an organic solvent having an evaporation rate of 30 to 60, where the evaporation rate of butyl acetate is taken as 100.

5. Contains 2.5 to 10.0 mass% carbon black, The solvent contains 80.0% by mass or more of an organic solvent having an evaporation rate of 20 to 80% when the evaporation rate of butyl acetate is taken as 100, A non-aqueous inkjet ink composition containing a resin is used. Inkjet printing is performed on a printing substrate made of resin and / or a printing portion previously formed on the surface of the printing substrate, Drying is carried out by infrared irradiation. A method of printing with a non-aqueous ink jet ink composition.

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