JP5151221B2 - Inkjet recording method - Google Patents

Description

  The present invention relates to a novel ink jet recording method.

  The ink jet recording method can cope with a wide variety of printing with a relatively small and inexpensive apparatus, but printing on a non-water-absorbing recording medium such as a film is limited to a special ink, and printing with an aqueous ink is difficult.

  Patent Document 1 describes a printing method in which an untreated vinyl sheet or a base coated with vinyl is printed with a piezo printing system having at least one heating device. The printing ink comprises a liquid medium, a water-insoluble colorant, a polymer binder, a drying inhibitor and other additives, and the liquid medium has a composition of water and a water-miscible drying inhibitor, and the liquid medium is at least 80% by mass. In this case, an ink having a drying inhibitor containing at least butyl diglycol and 1-methoxypropanol-2 and having an ink pH value greater than 8.5 is used.

  A non-water-absorbing recording medium printed by inkjet may be used as it is for wall-pasting advertisements or the like, but there are many requests for other applications.

  For example, when a printed material is pasted on a glass or the like for decoration purposes, if the thickness of the recording medium is thick, the place where the print is pasted is not preferable because it is too conspicuous. In addition, when the recording medium is transparent, it is not preferable that the transparency of the portion where the ink is not placed is significantly different from the attached glass.

  In addition, when a printed material is pasted on a non-planar object, it is very difficult to paste a print following the unevenness of the object.

  Further, when a plurality of prints are pasted on top of each other, the level difference is very conspicuous and the aesthetic appearance is impaired.

  Furthermore, in order to improve image fastness such as abrasion resistance, the recording surface may be affixed to another substrate with the recording surface inside, but also at this time, if the recording medium is thick, the reflectance of the recording medium is Since it does not match the reflectance of the pasted substrate, a gloss difference is generated, which is not preferable.

  In addition, when sandwiching a printed material between two substrates, for example, glass, there are gaps between the glass by the thickness of the substrate, which makes the appearance extremely dull, and moisture and dust are likely to enter from the gaps. is there.

  In the use method as described above, the thickness of the recording medium is particularly greatly affected. As a result of repeated studies by the present inventors, the influence becomes extremely large when the thickness of the recording medium exceeds 70 μm. It turned out to be undesirable. That is, it has been found that the use of the above-described application can be preferably performed without influence by using a very thin recording medium having a thickness of less than 70 μm.

  However, it is not known to use a very thin non-water-absorbing recording medium of less than 70 μm for ink jet recording. No such description is given in the above-mentioned Patent Document 1.

  In recent years, solvent inks used for signing and the like can be printed on a specific non-water-absorbing recording medium such as a vinyl chloride sheet, but the solvent in the ink dissolves or softens a resin such as vinyl chloride. If the film thickness is thin, high quality images cannot be obtained due to holes or deformation in the recording medium due to the ink. Usually, a vinyl chloride sheet having a thickness of about 150 μm is used, and no use example of a very thin non-water-absorbing recording medium having a thickness of less than 70 μm is found.

  In addition, the polymerizable monomer is used as the main component, and the photopolymerizable ink used together with the photopolymerization initiator can also be recorded on the non-absorbent recording medium. However, since all the main monomer of the ink is cured, the thickness of the ink layer However, when it is used for a very thin non-water-absorbing recording medium having a thickness of about 10 to 30 μm and less than 70 μm, the uneven feeling is strong and undesirable.

As described above, a non-water-absorbing recording medium of less than 70 μm by the ink jet recording method, a high-quality print maintaining a uniform thickness, the recording medium is dissolved or swollen, and defects are generated. There is no known method for printing without any harmful effects such as shrinkage.
JP 2005-113147 A

  Inkjet that can obtain high-quality prints that maintain a uniform thickness with no failure such as deformation of the recording medium or opening of holes on a non-water-absorbing recording medium having a thickness of 5 μm or more and less than 70 μm. It is to provide a recording method and to provide an inkjet recording method with high image durability.

  The object of the present invention can be achieved by the following.

  1. An ink jet recording method for recording with a water-based ink on a non-water-absorbing recording medium having a thickness of 5 μm or more and less than 70 μm. The water-based ink contains 5 to 30% by mass in total of glycol ether or alkanediol, and has a surface tension of 20 mN / An ink jet recording method comprising a fixing resin having a content of m or more and less than 30 mN / m and 2% by mass or more and less than 20% by mass.

  2. 2. The ink jet recording method according to 1, wherein the water-based ink contains 3 to 15% by mass of a polyhydric alcohol.

  3. 3. The ink jet recording method according to 1 or 2, wherein the fixing resin contains 2% by mass or more and less than 10% by mass of an ink-soluble resin and 1% by mass or more and less than 10% by mass of an ink dispersible resin.

  4). 4. The ink jet recording method according to any one of 1 to 3, wherein recording is performed by heating a non-water-absorbing recording medium.

  5). The ink jet recording method according to any one of 1 to 4, wherein the non-water-absorbing recording medium is affixed on another substrate.

  For non-water-absorbing recording media with a thickness of 5 μm or more and less than 70 μm, high-quality prints having a uniform thickness can be obtained without deformation or failure of the recording medium, and image durability can be obtained on the non-water-absorbing recording medium. High-performance ink jet recording can be obtained.

  The best mode for carrying out the present invention will be described below.

  First, the configuration of the present invention will be described in detail.

  The present inventor, in the case of pasting a printed material on transparent glass for decoration purposes, other than the application of using the printed material directly on a wall, such as a sign / advertisement application created using a solvent ink, In the usage method different from that for advertising such as pasting a printed matter on a non-planar object, pasting a plurality of prints on top of each other, pasting on another substrate with the recording surface inside In particular, it has been found that the thickness of the recording medium often has a great influence on the sense of unity with the base material, the sense of incongruity with the base material such as a difference in gloss, and the beautiful finish without unevenness. Furthermore, in the above cases, it has also been found that if the thickness of the recording medium exceeds 70 μm, the influence of the thickness of the recording medium becomes very large, which is not preferable.

  Further, among the water-based inks that are recorded on a very thin recording medium having a thickness of less than 70 μm as described above, the total amount of glycol ether or alkanediol is 5 to 30% by mass, and the surface tension is 20 mN / m or more and 30 mN / m. The present inventors have found that it is necessary to use a water-based ink containing a fixing resin that is less than m and less than 2% and less than 20%.

  Hereinafter, the configuration of the present invention will be described in more detail.

  The recording medium of the present invention may be a non-water-absorbing medium having a thickness of 5 μm or more and less than 70 μm.

  In the case of a water-absorbing medium, the strength surface is insufficient, and the film is peeled off or colored, which is not preferable in terms of durability. Further, in the case of paper or the like, cockling due to water-based ink occurs and wrinkles are not preferable.

  When the thickness of the non-water-absorbing recording medium is 70 μm or more, when a printed matter is pasted on a transparent glass or the like for decoration purposes, when a printed matter is pasted on a non-planar object, a plurality of prints may be printed. In the usage method, such as when pasting and pasting to other base materials with the recording surface facing inward, the thickness of the recording medium is not consistent with the base material, such as a sense of unity with the base material or gloss difference This is not preferable because it greatly affects the beauty of the finish without unevenness. From this viewpoint, the thickness is more preferably 50 μm or less. If it is less than 5 μm, it is severe in strength. That is, it is not possible to use it due to frequent transportation troubles. Preferably it is 10 micrometers or more, More preferably, it is 20 micrometers or more.

  Examples of the material of such a non-water-absorbing recording medium include polyethylene (low density product, high density product), EVA resin, polypropylene, polyvinyl chloride (soft, semi-rigid and transparent, PVC, semi-vinyl chloride), PET, Polyvinyl alcohol (high sapon value type), polyvinylidene chloride, polyamide, acrylic resin, and synthetic paper can be selected. In particular, polypropylene, polyvinyl chloride, PET and the like are preferable.

  Next, the ink used for the recording method of the present invention will be described.

  The ink used in the recording method of the present invention has a surface tension of 20 mN / m or more and less than 30 mN / m.

  Non-absorbent recording media include various media such as vinyl chloride, polypropylene, PET, and synthetic paper. For any recording medium, the surface tension of the water-based ink may be 20 mN / m or more and less than 30 mN / m in order to obtain high gloss without causing the ink to sufficiently wet and repel. preferable. Considering injection stability, a more preferable range is 25 mN / m or more and less than 29 mN / m. The surface tension is preferably adjusted by adding glycol ether or alkanediol in a total amount of 5 to 30% by mass and adding an activator. In particular, the activator is preferably adjusted using silicone or fluorine.

  The ink composition used in the recording method of the present invention contains a recording agent, 2% or more and less than 20% fixing resin, and, if necessary, an organic solvent, an activator, and the like.

(Recording agent)
As the ink recording agent, the recording agent may be a coloring recording agent such as a dye, a dispersible dye, or a pigment, or a functional recording agent such as a metal fine particle dispersion.

  A pigment is particularly preferable as the recording agent used in the present invention.

  The pigment used in the present invention is not particularly limited as long as it can be stably dispersed in an aqueous system, and can be dispersed without using a resin-dispersed pigment dispersed with a resin, a capsule pigment coated with a water-insoluble resin, or a pigment surface modified to use a dispersing resin. Self-dispersing pigments and the like. It is preferable to select a capsule pigment coated with a water-insoluble resin having good ink storage stability.

  When a resin dispersed pigment is used, a water-soluble resin can be used. As the water-soluble resin, a styrene-acrylic acid-acrylic acid alkyl ester copolymer and a styrene-acrylic acid copolymer are preferably used. Styrene-maleic acid copolymer, styrene-maleic acid-alkyl acrylate copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-alkyl acrylate copolymer, styrene-maleic acid half ester copolymer Water-soluble resins such as polymers, vinyl naphthalene-acrylic acid copolymers, vinyl naphthalene-maleic acid copolymers, and the like.

  Various methods such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, and a paint shaker can be used as a method for dispersing the pigment.

  For the purpose of removing the coarse particles of the pigment dispersion of the present invention, it is preferable to use a centrifugal separator or a filter.

  In the case of using a capsule pigment coated with a water-insoluble resin, the water-insoluble resin is a resin that is insoluble in water in a weakly acidic to weakly basic range, and preferably has a solubility in an aqueous solution having a pH of 4 to 10. Is less than 2% resin.

  Such water-insoluble resins include acrylic, styrene-acrylic, acrylonitrile-acrylic, vinyl acetate, vinyl acetate-acrylic, vinyl acetate-vinyl chloride, polyurethane, silicon-acrylic, acrylic silicon , Polyester-based, and epoxy-based resins.

  As the water-insoluble resin, a resin obtained by copolymerizing a hydrophobic monomer and a hydrophilic monomer can be used.

  Examples of hydrophobic monomers include acrylic acid esters (such as n-butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate), methacrylic acid esters (such as ethyl methacrylate, butyl methacrylate, glycidyl methacrylate), styrene. Etc. are raised.

  Examples of the hydrophilic monomer include acrylic acid, methacrylic acid, acrylamide, and the like, and those having an acidic group such as acrylic acid can preferably be those neutralized with a base after polymerization.

  As the molecular weight of the water-insoluble resin, those having an average molecular weight of 3,000 to 500,000 can be used. Preferably, 7,000 to 200,000 can be used.

  The water-insoluble resin having a Tg of about -30 ° C to 100 ° C can be used. Preferably, about -10 degreeC to 80 degreeC can be used.

  As the polymerization method, solution polymerization or emulsion polymerization can be used. The polymerization may be separately synthesized with the pigment in advance, or the monomer may be supplied to the system without dispersing the pigment for polymerization.

  Various known methods can be used as a method for coating the pigment with the resin. Preferably, in addition to the phase-emulsification method and the acid precipitation method, the pigment is dispersed using a polymerizable surfactant. It is preferable to select from a method in which a monomer is fed to the substrate and coating is performed while polymerizing.

  As a more preferred method, the water-insoluble resin is dissolved in an organic solvent such as methyl ethyl ketone, and after partially or completely neutralizing the acidic groups in the resin with a base, the pigment and ion-exchanged water are added and dispersed. After that, a production method in which the organic solvent is removed and is adjusted by adding water as necessary is preferable.

  The mass ratio of the pigment to the resin can be selected in the range of 100/40 to 100/150 as the pigment / resin ratio. In particular, the range of 100/60 to 100/110 has good image durability, injection stability, and ink storage stability.

  The average particle size of the pigment particles coated with the water-insoluble resin is preferably about 80 to 150 nm from the viewpoint of ink storage stability and color developability.

  Further, as the self-dispersing pigment, a surface-treated commercial product can also be used, for example, CABO-JET200, CABO-JET300 (manufactured by Cabot Corporation), Bonjet CW1 (manufactured by Orient Chemical Industry Co., Ltd.) and the like. Can be mentioned.

  As the pigment, conventionally known organic and inorganic pigments can be used as the pigment that can be used in the present invention. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc. Examples include cyclic pigments, dye lakes such as basic dye lakes, and acid dye lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments, and inorganic pigments such as carbon black.

  Specific organic pigments are exemplified below.

  Examples of pigments for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the orange or yellow pigment include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. And CI Pigment Yellow 138.

  Examples of pigments for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  Next, the fixing resin will be described.

(Fixing resin)
The water-based ink needs to contain 2% or more and less than 20% fixing resin. By including a fixing resin of 2% or more and less than 20%, the durability of the image on a very thin recording medium is improved, and by adding a resin, high-quality prints with reduced ink mixing can be achieved. Can be obtained. This is considered to be because the addition of the fixing resin increases the dry thickening and the adjacent inks mix with each other, thereby causing beading and color bleeding and not causing deterioration in image quality.

  If it is less than 2%, the image durability is insufficient and high image quality cannot be obtained, and if it is 20% or more, the injection stability is poor and cannot be put into practical use.

  As such a fixing resin, either an ink-soluble resin or an ink-dispersible resin can be used.

  In order to achieve more satisfactory dry thickening properties, ink ejection stability, and image fixing properties, it is necessary to use an ink-soluble resin and an ink-dispersible resin (resin dispersed in the ink) in combination. preferable. In particular, the fixing resin preferably contains 2% or more and less than 10% of an ink-soluble resin and 1% or more and less than 10% of an ink-dispersible resin.

  The ink-soluble resin is preferably a resin having a solubility of at least about 10% with respect to the ink vehicle. As an ink-soluble resin, it has a function as a binder resin for improving the durability of an image, so it is stably dissolved in ink, but is water-resistant after drying on media. Is preferred.

  As such a resin, a resin having a hydrophobic component and a hydrophilic component in a predetermined balance is designed and used. At this time, as the hydrophilic component, either an ionic or nonionic component may be used, but an ionic component is more preferable, and an anionic component is more preferable. In particular, those which are rendered water-soluble by neutralizing anionic substances with a volatile base component are preferred.

  In particular, at least one of the ink-soluble resins has a carboxyl group or a sulfonic acid group as an acidic group, and a resin having an acid value of 80 or more and less than 300 is preferable in view of the effects of the present invention.

  Examples of such resins include acrylic resins, styrene-acrylic resins, acrylonitrile-acrylic resins, vinyl acetate-acrylic resins, polyurethane resins, and polyester resins.

  As the ink-soluble resin of the present invention, a resin obtained by copolymerizing a hydrophobic monomer and a hydrophilic monomer can be used.

  Examples of hydrophobic monomers include acrylic acid esters (such as n-butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate), methacrylic acid esters (such as ethyl methacrylate, butyl methacrylate, glycidyl methacrylate), styrene. Etc. are raised.

  Examples of the hydrophilic monomer include acrylic acid, methacrylic acid, acrylamide, and the like, and those having an acidic group such as acrylic acid can preferably be those neutralized with a base after polymerization.

  As the molecular weight of the resin, an average molecular weight of 3,000 to 30,000 can be used. Preferably, 7,000 to 20,000 can be used.

  Resin having a Tg of about -30 ° C to 100 ° C can be used. Preferably, about -10 degreeC to 80 degreeC can be used.

  A resin having an acid value of about 90 to 200 can be particularly preferably used.

  As the polymerization method, it is preferable to use solution polymerization.

  The acidic group derived from the acidic monomer of the resin is preferably neutralized partially or completely with a base component. As the neutralizing base in this case, alkali metal-containing bases such as Na hydroxide, K, etc., and amines (ammonia, alkanolamine, alkylamine etc. can be used) can be used.

  In particular, neutralization with amines having a boiling point of less than 200 ° C. is particularly preferable from the viewpoint of improving image durability.

  As the ink dispersible resin, a dispersion polymerized in an aqueous system may be used as it is or may be treated, or a polymer polymerized in a solvent system may be dispersed in an aqueous system. It can be selected from urethane, styrene, vinyl acetate, vinylidene chloride, vinyl chloride, styrene-butadiene, styrene-acrylonitrile, polybutadiene, polyethylene, polyisobutylene, polyester, and the like.

  As the physical properties of the ink, it is preferable that there is no shear dependency on the viscosity. From this viewpoint, as a dispersion form of the polymer fine particles, an emulsifier such as an active agent is made as low as possible, or a soap-free aqueous dispersion polymer that does not use an emulsifier. Fine particles are preferred.

  A preferred aqueous dispersion polymer fine particle is a self-dispersion dispersion of a copolymer obtained by polymerizing unsaturated vinyl having a carboxyl group as at least a monomer component. For example, an acrylic monomer such as ethyl acrylate alone or an acrylic monomer is used. Mechanical dispersion is obtained by swelling a dispersion obtained by emulsion polymerization or suspension polymerization of acrylic acid or maleic acid as a carboxylic acid monomer into a composition comprising an ethylenically unsaturated monomer that can be copolymerized with a monomer, and then mechanically shearing. Is an acrylic hydrosol obtained by dividing the particles. Among acrylic hydrosols, it is preferable to contain styrene in the monomer composition from the viewpoint of increasing the refractive index of the resin and obtaining a high gloss feeling.

  Examples of the alkali include ammonia, triethylamine, 2-dimethylaminoethanol, 2-di-n-butylaminoethanol, methyldiethanolamine, 2-amino-2-methyl-1-propanol, diethanolamine, triethanolamine, and 2-methylaminoethanol. Amine is preferable, and ammonia, 2-amino-2-methyl-1-propanol, and 2-methylaminoethanol are particularly preferable in terms of dispersion stability of the aqueous dispersion polymer fine particles.

  As said acrylic hydrosol, John Crill (trademark) of Johnson Polymer Co., Ltd. etc. are marketed.

  The glass transition temperature (Tg) of the water-dispersible polymer fine particles is preferably 35 ° C. or higher in order to increase the scratch resistance of the image, and more preferably 49 ° C. or higher. Although the upper limit of Tg is not particularly limited, a flexible ink film can be obtained when the temperature is generally less than 100 ° C., and cracking failure of an image due to bending of a printed matter can be prevented. The acid value of the aqueous dispersion polymer fine particles is preferably 44 or more, more preferably 60 or more, from the viewpoint of obtaining good redispersion / solubility of the ink dry film. The upper limit of the acid value is not particularly limited, but is preferably less than 110 from the viewpoint of easily obtaining a more stable dispersion.

  The average particle size of the water-dispersed polymer fine particles is preferably 300 nm or less, more preferably 130 nm or less, from the viewpoint that there is no clogging in the head nozzle and a good gloss can be obtained. The lower limit of the average particle diameter is preferably 30 nm or more from the viewpoint of the production stability of the fine particles. The average particle diameter of the water-dispersed polymer fine particles can be easily measured using a commercially available measuring device using a light scattering method or a laser Doppler method. Alternatively, the dispersion of the aqueous dispersion polymer fine particles can be freeze-dried, and the average particle diameter can be converted from the particles observed with a transmission microscope.

  As the organic solvent in the ink, a water-soluble or miscible solvent in the ink can be used. In particular, the total content of glycol ether or alkanediol is preferably 5 to 30% by mass.

  In addition, it is more preferable to contain 3 to 15% by mass of polyhydric alcohol.

  By containing 5 to 30% by mass of glycol ether or alkanediol as a total amount, wettability is improved with respect to various non-water-absorbing recording media. At the same time, it is easy to increase the viscosity when ink is dried, and a high-quality print with reduced ink mixing can be obtained. Some solvents may deform the non-water-absorbing recording medium, but an ink containing 5 to 30% by mass of glycol ether or alkanediol as a total amount is preferable because such a phenomenon hardly occurs.

In particular, in order to obtain a sufficiently high color density for a non-water-absorbing polymer recording medium having a thickness of 5 μm or more and less than 70 μm of the present invention, an ink maximum application amount of about 10 ml to ²⁰ ml / m ² is required. In order to prevent failure of the non-water-absorbing polymer recording medium having a thickness of 5 μm or more and less than 70 μm with this ink, it is necessary to contain 5 to 30% by mass of glycol ether or alkanediol as a total amount.

  Specific examples of glycol ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, and tripropylene glycol monomethyl ether. Can be mentioned.

  Examples of the alkanediol include 1,2-alkanediols such as 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, and the like.

  Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, and thiodiglycol. Is mentioned.

  When the polyhydric alcohol is contained in an amount of 3 to 15% by mass, the injection stability is preferably improved without greatly affecting the image quality and the drying property.

  In addition, an aqueous liquid medium is preferably used as the solvent that can be used, and a mixed solvent such as water and a water-soluble organic solvent is preferably used as the aqueous liquid medium. Specific examples of the water-soluble organic solvent preferably used include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol), amines (for example, ethanolamine). , Diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine) Amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocyclic rings For example, 2-pyrrolidone, N- methyl-2-pyrrolidone, cyclohexyl pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone), sulfoxides (e.g., dimethyl sulfoxide) and the like.

(Surfactant)
For the water-based ink, a silicone-based or fluorine-based surfactant can be preferably used. In particular, when used in combination with glycol ether or alkanediol, a high-quality image with reduced ink mixing can be obtained.

  The silicone-based surfactant is preferably a polyether-modified polysiloxane compound, and examples thereof include KF-351A and KF-642 manufactured by Shin-Etsu Chemical, BYK347 and BYK348 manufactured by Big Chemie.

  The fluorine-based surfactant means a compound in which a part or all of the surfactant is substituted with fluorine in place of hydrogen bonded to carbon of the hydrophobic group of a normal surfactant. Of these, those having a perfluoroalkyl group in the molecule are preferred.

  Among the fluorine-based surfactants, certain types are traded under the trade name Megafac F from Dainippon Ink & Chemicals, and Surflon from Asahi Glass, Minnesota Mining and Under the trade name Fluorad FC from Manufacturing Company, under the trade name Monflor from Imperial Chemical Industry, and Zonyls from EI Dupont Nemeras & Company. It is commercially available under the trade name and also under the trade name Licobet VPF from Farbeberke Hoechst.

  Examples of nonionic fluorosurfactants include Megafax 144D manufactured by Dainippon Ink and Surflon S-141 and 145 manufactured by Asahi Glass Co., and amphoteric fluorosurfactants. Examples of the agent include Surflon S-131 and 132 manufactured by Asahi Glass Co., Ltd.

  In the ink jet recording method of the present invention, it is particularly preferable to record by heating the recording medium.

  By heating the recording medium, the drying and thickening speed of the ink is remarkably improved, and high image quality can be obtained. Also, the durability of the image is improved.

  The heating temperature is preferably such that the recording surface temperature of the recording medium is 40 ° C to 80 ° C. Heating below 40 ° C. is not preferable because the image quality is insufficient and sufficient image durability cannot be obtained, and it takes time to dry. If the temperature exceeds 80 ° C., the ink ejection is greatly affected and cannot be printed stably.

  More preferably, the recording surface temperature of the recording medium is 40 ° C. to 60 ° C.

  As a heating method, a method in which a heating heater is incorporated in the recording medium conveyance system or the platen member and heated from the lower side of the recording medium, or a method of heating from the lower side or from the upper side by a lamp or the like can be selected. .

  In the recording method of the present invention, printing may be performed on a sheet-shaped or roll-shaped recording medium, or recording may be performed after the recording medium is attached to another substrate in advance.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Example (Synthesis of ink-soluble fixing resin)
<Synthesis of Ink Soluble Fixing Resin R1>
50 g of methyl ethyl ketone was added to a flask equipped with a dropping funnel, a nitrogen introducer, a reflux condenser, a thermometer and a stirrer, and heated to 75 ° C. while bubbling nitrogen. The mixture of the monomer of the amount of Table 3, 50 g of methyl ethyl ketone, and 500 mg of initiator (AIBN) was dripped there over 3 hours from the dropping funnel. After the dropwise addition, the mixture was further heated to reflux for 6 hours. After allowing to cool, the mixture was heated under reduced pressure to distill off methyl ethyl ketone. In 450 ml of ion-exchanged water, dimethylaminoethanol corresponding to 1.05 mol of acrylic acid added as a monomer was dissolved, and the polymer residue was dissolved therein. A resin aqueous solution having a solid content concentration of 20% was obtained by adjusting with ion-exchanged water.

  As the ink dispersible fixing resin D1 in the ink, the composition: styrene / α-methylstyrene / 2-ethylhexyl acrylate / acrylic acid, Tg: 75 ° C., acid value: 82, and average particle size: 130 nm were used.

(Preparation of pigment dispersion)
<Synthesis of dispersion resin>
50 g of methyl ethyl ketone was added to a flask equipped with a dropping funnel, a nitrogen introducer, a reflux condenser, a thermometer and a stirrer, and heated to 75 ° C. while bubbling nitrogen. The mixture of the monomer of the amount of Table 1, 50 g of methyl ethyl ketone, and 500 mg of initiator (AIBN) was dripped there over 3 hours from the dropping funnel. After the dropwise addition, the mixture was further heated to reflux for 6 hours. After being allowed to cool, methyl ethyl ketone was added to volatilize to obtain a resin solution having a solid content of 50% by mass.

<Preparation of pigment dispersion P1>
To 100 g of a 50% mass solution of the synthesized dispersion resin in methyl ethyl ketone, a predetermined amount of a 20% aqueous sodium hydroxide solution was added as a neutralizing agent to neutralize the salt-forming groups to 100%, and while stirring, C.I. I. Pigment Blue 15: 3 and 50 g were added little by little, and then kneaded in a bead mill for 2 hours. To the obtained kneaded product, 400 g of ion-exchanged water was added and stirred, followed by heating under reduced pressure to distill off methyl ethyl ketone. Further, ion exchange water was added to obtain a pigment dispersion P1 having a solid concentration of 15% by mass.

(Ink preparation)
After mixing and preparing the ink as described in Tables 1 and 2, it was filtered through a 5 μm filter. In Tables 1 and 2, the pigment dispersion, additive resin, solvent, and activator are added so that the mass percentages of the numbers in Tables 1 and 2 respectively are added, and ion-exchanged water is added so that the total amount is 100 mass%. (However, the pigment concentration is the solid content). In Tables 1 and 2, DEGBE and 1,2-HD represent diethylene glycol monobutyl ether, 1,2-hexanediol, PG, and DEG represent propylene glycol and diethylene glycol, respectively. The surfactant Si represents KF-351A manufactured by Shin-Etsu Chemical.

As the solvent ink of Comparative Example 26, a cyan ink of ECO-SOL MAX (manufactured by Roland DG) was used.
As the UV ink of Comparative Example 27, cyan ink of JF series (Mimaki Engineering Co., Ltd.) was used.

Example 1
Recording was performed on various recording media having different thicknesses, and the following evaluation was performed.

  Evaluation was carried out using a printing apparatus capable of four-color printing in which four piezo-type heads (720 dpi, appropriate amount of liquid 16 pl) were arranged in parallel. The apparatus can arbitrarily heat the media from below with a contact heater. In addition, an ink emptying position and a blade wipe type maintenance unit are provided at the head storing position, and the head can be cleaned at an arbitrary frequency.

  Evaluation 1 (Monochromatic image evaluation): Each ink was introduced into one head of the evaluation apparatus, and a monochromatic image was created for evaluation. The evaluation conditions are as follows.

Printing resolution: 720 dpi x 720 dpi
(Dpi: number of dots per 2.54 cm)
Head transport speed: 200 mm / sec Bidirectional printing Media heating temperature: Print surface temperature 50 ° C
Evaluation image: wedge image, text, white text Evaluation environment: 20 ° C, relative humidity 55%
Further, the print using the comparative UV ink (Comparative Image No. 27) was subjected to UV exposure with a UV irradiation device (metal halide lamp output 120 W) immediately after printing.

(Evaluation item 1): Presence or absence of defects caused by printing Evaluation 1 Failure to use holes due to holes in recording media and large deformations cannot be used. Evaluation 2 Although there are no failures to open holes, deformation has been observed but they cannot be used. Evaluation 3 Slightly Deformation is seen but usable level evaluation 4 Almost no deformation is observed.

  In addition, subsequent evaluation is not performed about the image material which became the evaluation 1 by the evaluation item 1.

(Evaluation item 2): Image quality evaluation Evaluation 1 Cannot be used because repellency is observed Evaluation 2 Cannot be used because there is no repellency Evaluation 3 Level of beading that can be used although there is a slight beading in part of the image Evaluation 4 There is almost no beading.

(Evaluation item 3): Evaluate the finish when the printed image is pasted on a transparent glass with a thickness of 3 mm so that the printed surface is exposed to the surface. You can see immediately.

Evaluation 2 Gloss difference, uniformity of thickness, etc. Evaluation 3 I don't care about gloss difference, uniformity of thickness, etc. There is a sense of unity between the image and the glass substrate, and it looks as if it was printed directly.

(Evaluation item 4): Evaluate the finish when the printed image is pasted on a cosmetic bottle in which unevenness is dug so that the printed surface is exposed on the surface. Evaluation 1 There is an unadhered portion in the concave portion, and air enters. Image of that part is not noticeably unfavorable, and gloss difference and thickness difference are considerably worrisome Evaluation 2 There is an unbonded part in the concave part, air enters, and the image of that part is not noticeable unfavorable. Evaluation 3 Following the unevenness A film can be attached, but worries about gloss difference and thickness uniformity Evaluation 4 A film can be affixed to follow unevenness, and the gloss difference and thickness uniformity do not bother and make up with images There is a sense of unity in the bottle, and it looks beautiful as if it were printed directly.

(Evaluation item 5): Evaluate the finish when 3 images printed separately are pasted on 10 mm thick translucent glass. Evaluation 1 The thickness of the image is worrisome, and it is glaring when viewed from an angle. Evaluation 2 Image The thickness of is slightly worrisome and slightly glaring when viewed from an angle. Evaluation 3 Beautiful finish with almost no image thickness (Evaluation item 6): The created image was pasted on a transparent glass with a thickness of 3 mm. At this time, image scraping was evaluated by rubbing 10 times with a scraper (made of rubber).

Evaluation 1 Some images are removed. Evaluation 2 Slightly taken Evaluation 3 The rubber is colored, but the appearance of the image is almost unchanged. Evaluation 4 No change.

Example 2
Ink ejection properties were also evaluated under the following conditions.

  After creating 30 images (A4 size) continuously, images were created again at intervals of 40 minutes to evaluate the images.

Evaluation 1: Many image defects (improper ink ejection) are observed. Evaluation 2: Image defects are observed. Evaluation 3: Although there are almost no image defects, the lowercase drawing is deteriorated. When magnified, satellites were seen on the dots.

Evaluation 4: There is no image defect, but a slight fading is seen in the image writing portion (several mm). Evaluation 5: No image defect is seen including the image writing portion.

Example 3
Transparent PET having a thickness of 20 μm was pasted on a white tile, and printing was performed using ink 1 thereon. The printing conditions were the same as in Example 1, and the tile was heated to 50 ° C.

  There was no deformation of PET in the image area, no concern about gloss difference and thickness uniformity, and the finish was beautiful as if it were printed directly.

Example 4
PET having a thickness of 10 μm was pasted on a transparent glass having a thickness of 10 mm, printing was performed using the ink 1, and a transparent glass having a thickness of 10 mm was pasted on the printing surface. Looking through the glass, almost no deformation of the PET was seen, and the finish was homogeneous and beautiful.

Claims (4)

An inkjet recording method for recording with a water-based ink on a non-water-absorbing recording medium having a thickness of 5 μm or more and less than 70 μm,
The water-based ink is
Containing 5 to 30% by mass of glycol ether or 4 to 7 carbon 1,2-alkanediol as a total amount,
3 polyhydric alcohols selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, and thiodiglycol From 5% by mass to 5% by mass,
2% by mass or more and less than 20% by mass of a fixing resin,
Ink jet recording method surface tension, characterized in that it is a less than 20 mN / m or more 30 mN / m. 2. The ink jet recording method according to claim 1, wherein the fixing resin contains 2% by mass or more and less than 10% by mass of an ink-soluble resin and 1% by mass or more and less than 10% by mass of an ink dispersible resin. . The inkjet recording method according to claim 1 , wherein the non-water-absorbing recording medium is heated for recording. The inkjet recording method according to any one of claims 1 to 3 , wherein the non-water-absorbing recording medium is affixed on another substrate.