JP5878735B2 - Non-aqueous pigment ink for inkjet - Google Patents

Description

  The present invention relates to a non-aqueous pigment ink for inkjet.

  The ink jet recording method is a method in which an ink having a high fluidity is ejected as ink particles from a fine head nozzle, and an image is recorded on a recording medium such as paper placed opposite to the nozzle. In particular, when a line head type ink jet recording apparatus having a large number of ink heads is used, high-speed printing is possible, so that it has rapidly spread in recent years.

  As an ink used in such an ink jet recording method, there is a so-called non-aqueous pigment ink in which a pigment is dispersed in a non-aqueous solvent. The non-aqueous pigment ink for inkjet is not an ink that dries and solidifies on the paper itself, but is an osmotic drying type ink in which the ink penetrates and dries inside the paper. It has attracted attention because it has features such as good discharge recovery after standing, no paper curl, and short ink permeation drying time.

  In non-aqueous pigment inks, a pigment dispersant that dissolves in a solvent is generally used. Since the pigment dispersant increases the affinity between the solvent and the pigment, the pigment is also drawn into the paper when the solvent penetrates the paper. It tends to be easy. As a result, the print density is lowered, and there is a possibility that show-through occurs.

  In addition, when the paper that has landed on the paper surface is undried and the paper is transported by the transport roller, so-called roller transfer stains may occur. That is, undried ink adheres to the transport roller, and the ink that adheres to the transport roller is transferred to the area downstream in the transport direction of the same paper or to the next transported paper, causing ink stains on the paper. There is. This roller transfer stain is a problem particularly in high-speed printing when the time from ink landing to conveyance by the conveyance roller is short.

  Patent Document 1 discloses a non-aqueous resin-dispersed fine particle having a specific pigment-dispersing ability in order to provide a non-aqueous pigment ink that suppresses show-through of printed matter to increase print density and is excellent in storage stability. Non-aqueous pigment inks have been proposed. Further, paragraph 0039 of Patent Document 2 describes a polar organic solvent for the purpose of improving the adhesion of the non-aqueous pigment ink to the recording medium, or for the purpose of adjusting the spread of non-aqueous pigment ink dots on the recording medium. It has been proposed to add a resin that dissolves in

  However, generally, when a solid resin is added to the ink, the viscosity of the ink increases and roller transfer stains are likely to occur. Thus, there is a problem that it is difficult to achieve both performances.

JP 2010-1452 A Japanese Patent Laid-Open No. 2004-2666

  An object of the present invention is to provide a non-aqueous pigment ink for inkjet which prevents transfer stains, has a high printing density, and has reduced back-through.

  One aspect of the present invention is a non-aqueous pigment ink for inkjet including an acid-modified petroleum hydrocarbon resin, a pigment, and a non-aqueous solvent.

  ADVANTAGE OF THE INVENTION According to this invention, the non-aqueous pigment ink for inkjets which prevented transfer stain | pollution | contamination, has high printing density, and reduced show-through can be provided.

  Hereinafter, although the embodiment concerning the present invention is described, the illustration in this embodiment does not limit the present invention.

  An ink-jet non-aqueous pigment ink according to an embodiment of the present invention (hereinafter sometimes simply referred to as “ink”) includes an acid-modified petroleum hydrocarbon resin, a pigment, and a solvent. Accordingly, it is possible to provide a non-aqueous pigment ink for inkjet which prevents transfer stains, has a high printing density, and has reduced back-through.

  By adding an acid-modified petroleum-based hydrocarbon resin to the ink, transfer stains can be prevented, the printing density can be increased, and back-through can be reduced. This is thought to be due to the fact that the acid-modified petroleum-based hydrocarbon resin is contained in the ink, so that when the ink lands on the recording medium, the solvent detachability of the ink is improved. That is, since the acid-modified petroleum hydrocarbon resin is poorly soluble in non-aqueous solvents including petroleum solvents, the non-aqueous solvent in the ink is released as soon as the ink lands on the recording medium. It is considered that the acid-modified petroleum hydrocarbon resin and the pigment penetrate inside and stay on the surface of the recording medium. Thus, if the solvent detachability is good, the ink can be quickly dried and fixed, and transfer stains can be prevented. In addition, the good solvent detachability makes it difficult for the pigment in the ink to penetrate into the recording medium together with the non-aqueous solvent after the ink has landed on the recording medium, and the pigment diffuses together with the non-aqueous solvent on the surface of the recording medium. Therefore, the print density can be increased and the show-through can be reduced.

  The petroleum-based hydrocarbon resin constituting the acid-modified petroleum-based hydrocarbon resin is not particularly limited, but C5-based petroleum resins made from pentene, pentadiene, isoprene, etc., indene, methylindene, vinyltoluene, styrene, α- C9 petroleum resin made from methyl styrene, β-methyl styrene, etc., DCPD (dicyclopentadiene) petroleum resin made from cyclopentadiene, dicyclopentadiene, etc. Examples thereof include copolymerized petroleum petroleum resins.

  The acid-modified petroleum hydrocarbon resin is obtained by treating a petroleum hydrocarbon resin with an unsaturated carboxylic acid or an anhydride thereof, and adding an unsaturated carboxylic acid or an acid anhydride thereof and an alcohol to the petroleum hydrocarbon resin. It can be obtained by reaction.

  The acid-modified petroleum hydrocarbon resin preferably has an aromatic hydrocarbon group. As a result, the aromatic hydrocarbon group of the acid-modified petroleum hydrocarbon resin exhibits an adsorptive action on the pigment, the adsorptivity between the acid-modified petroleum hydrocarbon resin and the pigment increases, the solvent detachability further increases, and the transfer stains It is possible to further enhance the effects of prevention of printing, improvement of printing density and reduction of showthrough.

  Examples of acid-modified petroleum hydrocarbon resins having aromatic hydrocarbon groups include C9 petroleum resins and copolymer petroleum resins of C9 petroleum resin raw materials and C5 petroleum resin raw materials and / or DCPD petroleum resin raw materials. Preferably, it is a copolymerized petroleum resin of a C9 petroleum resin raw material and a C5 petroleum resin raw material.

As unsaturated carboxylic acid or its acid anhydride, it is C3-C36, for example, More preferably, it is a C3-C18 thing. Examples of the unsaturated carboxylic acid or anhydride thereof include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, cinnamic acid and the like, and anhydrides thereof. In particular, acrylic acid, methacrylic acid, maleic acid, maleic anhydride and the like are preferably used from the viewpoint of reactivity and cost.
The amount of the unsaturated carboxylic acid or acid anhydride used is preferably 0.1 to 15% by mass, more preferably 0.1 to 10% by mass, based on the petroleum hydrocarbon resin.

  As the alcohol, for example, a monohydric alcohol, a polyhydric alcohol, or a combination thereof can be used.

  Examples of the monohydric alcohol include 1-butanol, 1-hexanol, 1-octanol, 2-ethylhexanol, 1-dodecanol, 1-octadecanol, 1-docosanol and other linear alcohols, benzyl alcohol, naphthyl alcohol, and the like. Can be mentioned.

  Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butylene glycol, neopentyl glycol, hexanediol, glycerin, trimethylolpropane, and ditrimethylol. Examples thereof include linear alcohols such as propane, pentaerythritol, dipentaerythritol, and D-sorbitol, and alicyclic alcohols such as 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol.

  The amount of alcohol used is, for example, 0.3 to 2 equivalents, preferably 0.4 to 1.5 equivalents of a hydroxyl group with respect to 1 equivalent of the carboxyl group of the unsaturated carboxylic acid or its anhydride. It is preferable to do.

  The reaction procedure for acid modification is not particularly limited. For example, petroleum hydrocarbon resin, unsaturated carboxylic acid or anhydride thereof, and alcohol may be mixed, non-catalyst or catalyst may be added, and heated reaction may be performed simultaneously. Alternatively, the petroleum hydrocarbon resin and the unsaturated carboxylic acid or anhydride thereof may be preliminarily heated and then esterified by adding an alcohol.

  The acid-modified petroleum hydrocarbon resin can be blended in an amount of 15% by mass or less, more preferably 10% by mass or less, and still more preferably 5% by mass or less based on the whole ink. When the content is 15% by mass or less, an increase in ink viscosity can be suppressed, occurrence of transfer stains can be prevented, and discharge performance is also excellent. Further, in order to sufficiently obtain the effects of preventing the transfer stain, improving the printing density and reducing the back-through by the action of solvent detachment, the acid-modified petroleum hydrocarbon resin is 0.1 mass relative to the whole ink. % May be added, more preferably 1% by mass or more, and still more preferably 3% by mass or more.

  In addition, the acid-modified petroleum hydrocarbon resin can be blended in a mass ratio of 0.1 to 15 in terms of solid content with respect to the pigment 1, more preferably 0.3 to 5, and even more preferably. 0.3-1.

  The acid value of the acid-modified petroleum hydrocarbon resin can be 25 (mgKOH / g) or less, and preferably 20 (mgKOH / g) or less. When the acid value is 25 (mgKOH / g) or less, the dispersibility of the ink can be stably maintained. In addition, in order to obtain a sufficient solvent releasing action, the acid value of the acid-modified petroleum hydrocarbon resin can be 0.1 (mg KOH / g) or more, preferably 0.5 (mg KOH / g). g) or more, and more preferably 5.0 (mg KOH / g) or more.

  The acid value of the acid-modified petroleum hydrocarbon resin can be prepared by the blending amount of carboxylic acid or its anhydride or alcohol in the above-described acid-modified reaction procedure. Alternatively, the acid-modified petroleum hydrocarbon resin may be prepared by mixing with other acid-modified petroleum hydrocarbon resins having different acid values.

The number average molecular weight of the acid-modified petroleum hydrocarbon resin is preferably 300 to 3000, more preferably 300 to 1500, from the viewpoint of ink viscosity.
The softening point of the acid-modified petroleum hydrocarbon resin is preferably 60 to 140 ° C. from the viewpoint of ejection stability.

  Any number of pigments may be included in the ink according to the present embodiment. Examples of pigments for black ink include carbon blacks such as furnace black, lamp black, acetylene black, and channel black; copper, iron, titanium oxide, and the like. And organic pigments such as ortho-nitroaniline black. These can be used alone or in any desired mixture.

  Color ink pigments include toluidine red, permanent carmine FB, disazo orange PMP, lake red C, brilliant carmine 6B, quinacridone red, dioxane violet, orthonitroaniline orange, dinitroaniline orange, vulcan orange, toluidine red, chlorinated para red. , Brilliant First Scarlet, Naphthol Red 23, Virazolone Red, Barium Red 2B, Calcium Red 2B, Strontium Red 2B, Manganese Red 2B, Barium Resome Red, Pigment Scar Red 3B Lake, Lake Bordeaux 10B, Anthosine 3B Lake, Anthosine 5B Rake, Rhodamine 6G Rake, Eosin Rake, Bengala, Fattor Red FGR, Rhodamine B , Methyl bio red lake, dioxazine bio red, naphthol carmine FB, naphthol red M, fast yellow AAA, fast yellow 10G, disazo yellow AAMX, disazo yellow AAAT, disazo yellow AAOA, disazo yellow HR, isoindoline yellow, fast Yellow G, Disazo Yellow AAA, Phthalocyanine Blue, Pictoria Pure Blue, Basic Blue 5B Lake, Basic Blue 6G Lake, Fast Sky Blue, Alkaline Blue R Toner, Peacock Blue Lake, Bituminous Blue, Ultraviolet, Reflex Blue 2G, Reflex Blue R, alkali blue G toner, brilliant green lake, diamond green thioflavin lake, phthalocyanine green G Examples include green gold, phthalocyanine green Y, iron oxide powder, rust, zinc white, titanium oxide, calcium carbonate, clay, barium sulfate, alumina white, aluminum powder, bronze powder, daylight fluorescent pigment, pearl pigment, etc. May be used alone or in any mixture.

  The average particle diameter of the pigment is preferably 300 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less from the viewpoint of ejection stability and storage stability. Here, the average particle diameter of the pigment is a value measured by a dynamic light scattering particle size distribution analyzer LB-500 manufactured by Horiba, Ltd.

  The content of the pigment in the ink is usually 0.01 to 20% by mass, and preferably 3 to 15% by mass from the viewpoint of printing density and ink viscosity.

  In order to improve the dispersion of the pigment in the ink, it is preferable to add a pigment dispersant to the ink. The pigment dispersant is not particularly limited as long as the pigment is stably dispersed in the solvent. For example, a hydroxyl group-containing carboxylic acid ester, a salt of a long chain polyaminoamide and a high molecular weight acid ester, a high molecular weight polycarboxylic acid Salt, long chain polyaminoamide and polar acid ester salt, high molecular weight unsaturated acid ester, polymer copolymer, modified polyurethane, modified polyacrylate, polyether ester type anionic activator, naphthalenesulfonic acid formalin condensate salt Polyoxyethylene alkyl phosphate ester, polyoxyethylene nonylphenyl ether, polyester polyamine, stearylamine acetate and the like are used, and among them, a polymer dispersant is preferably used.

  Specific examples of the pigment dispersant include “Solsperse 5000 (phthalocyanine ammonium salt type), 13940 (polyesteramine type), 17000, 18000 (fatty acid amine type), 11200, 22000, 24000, 28000” manufactured by Nippon Lubrizol Co., Ltd. ( All are trade names), "Efka 400, 401, 402, 403, 450, 451, 453 (modified polyacrylate), 46, 47, 48, 49, 4010, 4055 (modified polyurethane)" manufactured by Efka CHEMICALS (all Product name), “Demol P, EP, Poise 520, 521, 530, Homogenol L-18 (polycarboxylic acid type polymer surfactant)” (both trade names) manufactured by Kao Corporation, “Made by Enomoto Kasei Co., Ltd.” Disparon KS-860, KS-873N (Amine salt of high molecular polyester) ”(all trade names),“ Discall 202, 206, OA-202, OA-600 (multi-chain polymer nonionic) ”manufactured by Daiichi Kogyo Seiyaku Co., Ltd. (any Product name).

  The blending amount of the pigment dispersant in the ink can be appropriately set, but from the viewpoint of pigment dispersibility, the mass ratio is preferably about 0.05 to 2.0 parts with respect to 1 part of the pigment, 0.1 More preferably, it is -1.5 parts. The pigment dispersant is preferably contained in an amount of about 0.5 to 15% by mass, and more preferably 1 to 12% by mass with respect to the whole ink.

  The non-aqueous solvent is a non-polar organic solvent or a polar organic solvent having a 50% distillation point of 150 ° C. or higher. The 50% distillation point means a temperature at which 50% by mass of a solvent is volatilized, which is measured according to JIS K0066 “Testing method for distillation of chemical products”. From the viewpoint of safety, the 50% distillation point of the non-aqueous solvent is preferably 160 ° C. or higher, and more preferably 230 ° C. or higher.

  For example, preferred examples of the nonpolar organic solvent include petroleum solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents. Examples of the aliphatic hydrocarbon solvent and alicyclic hydrocarbon solvent include “Tclean N-16, Tclean N-20, Tclean N-22, Nisseki Naphthezol L, Nisseki Naphthezol, manufactured by JX Nippon Mining & Energy Corporation. M, Nisseki Naphthezol H, No. 0 Solvent L, No. 0 Solvent M, No. 0 Solvent H, Nisseki Isosol 300, Nisseki Isosol 400, AF-4, AF-5, AF-6, AF-7 ", Exxon “Isopar G”, “Isopar H”, “Isopar L”, “Isopar M”, “Exxsol D40”, “Exxsol D80”, “Exxsol D100”, “Exxsol D130” and “Exxsol D140” manufactured by Japan Energy, etc. are preferable. it can. Preferred examples of the aromatic hydrocarbon solvent include “Nisseki Clean Sol G” (alkylbenzene) manufactured by Nippon Petroleum Corporation, “Solvesso 200” manufactured by Exxon, and the like.

  As the polar organic solvent, ester solvents, alcohol solvents, higher fatty acid solvents, ether solvents, and mixed solvents thereof can be used. For example, selected from the group consisting of an ester solvent that is an ester of a higher fatty acid having 8 to 20 carbon atoms and an alcohol having 1 to 24 carbon atoms, a higher alcohol having 8 to 24 carbon atoms, and a higher fatty acid having 8 to 20 carbon atoms. One or more of them can be preferably used.

More specifically, as polar organic solvents, methyl laurate, isopropyl laurate, isopropyl myristate, isooctyl myristate, isopropyl palmitate, isostearyl palmitate, methyl oleate, ethyl oleate, isopropyl oleate, butyl oleate , Methyl linoleate, isobutyl linoleate, ethyl linoleate, isopropyl isostearate, soybean oil methyl, soybean oil isobutyl, tall oil methyl, tall oil isobutyl, diisopropyl adipate, diisopropyl sebacate, diethyl sebacate, propylene glycol monocaprate Ester solvents such as trimethylolpropane tri-2-ethylhexanoate and glyceryl tri-2-ethylhexanoate; isomyristyl alcohol, isopalmityl Alcohol solvents such as alcohol, isostearyl alcohol, oleyl alcohol, hexyl decanol, octyldodecanol, and decyltetradecanol; higher grades such as nonanoic acid, isononanoic acid, isomyristic acid, hexadecanoic acid, isopalmitic acid, oleic acid, and isostearic acid Preferred examples include fatty acid solvents; ether solvents such as diethyl glycol monobutyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, and propylene glycol dibutyl ether.
These non-aqueous solvents can be used alone or in combination of two or more.

  In this embodiment, in order to improve solvent detachability, it is preferable that a petroleum solvent is included among the non-aqueous solvents described above. The petroleum solvent may be any of an aliphatic hydrocarbon solvent, an alicyclic hydrocarbon solvent, an aromatic hydrocarbon solvent, etc., but the acid-modified petroleum hydrocarbon resin is based on a C5 petroleum resin. When the resin is an aliphatic hydrocarbon solvent, it is preferably an aliphatic hydrocarbon solvent. The petroleum solvent is preferably 20% by mass or more, and more preferably 40% by mass or more, based on the total mass of the non-aqueous solvent.

  The non-aqueous solvent preferably contains an ester solvent and / or an alcohol solvent among the non-aqueous solvents described above in order to enhance the solubility of the acid-modified petroleum hydrocarbon resin together with the petroleum solvent. In particular, an ester solvent is preferably included. The ester solvent is preferably 10% by mass or more, and more preferably 30% by mass or more, based on the total mass of the non-aqueous solvent.

  As the alcohol solvent, an alcohol solvent having 8 to 22 carbon atoms is preferable from the viewpoint of solubility of the acid-modified petroleum hydrocarbon resin. For example, isomyristyl alcohol (carbon number 14), isocetyl alcohol (carbon number 16). ), Isostearyl alcohol (carbon number 18), oleyl alcohol (carbon number 18), dimerized alcohol by gerbet reaction or the like can be used. The content of the alcohol solvent is preferably 1% by mass or more, more preferably 5% by mass or more, based on the total mass of the non-aqueous solvent.

  The non-aqueous pigment ink of the present embodiment includes, for example, a nozzle clogging preventive agent, an antioxidant, a conductivity adjusting agent, a viscosity adjusting agent, a surface tension adjusting agent, an oxygen within a range that does not impair the effects of the present invention. Absorbers, fixing agents, preservatives, surfactants, and the like can be added as appropriate. These types are not particularly limited, and those used in the field can be used.

  The viscosity range of the non-aqueous pigment ink varies depending on the nozzle diameter of the ejection head, the ejection environment, and the like, but in general, it is preferably 5 to 30 mPa · s, preferably 5 to 15 mPa · s at 23 ° C. More preferably, the pressure is about 10 to 13 mPa · s. Here, the viscosity represents a value at 10 Pa when the shear stress is increased from 0 Pa at a rate of 0.1 Pa / s at 23 ° C.

  As an example of the production method, all components including acid-modified petroleum hydrocarbon resin, pigment and non-aqueous solvent are added to a disperser such as a bead mill at one time or divided and stirred and mixed. It is obtained by filtering through. For example, a pigment dispersion is prepared by preparing a mixed liquid in which a part of a non-aqueous solvent, the total amount of pigment, and optionally a pigment dispersant are uniformly mixed, and dispersing with a disperser, and the remaining non-aqueous solvent An acid-modified petroleum hydrocarbon resin is dissolved in a solvent to prepare a resin solution, and then the pigment dispersion and the resin solution are mixed and passed through a filter.

  The ink jet recording method using the non-aqueous pigment ink may be any method such as a piezo method, an electrostatic method, or a thermal method. When an ink jet recording apparatus is used, it is preferable that the ink according to the present embodiment is ejected from the ink jet head based on the digital signal, and the ejected ink droplets are attached to the recording medium.

  The recording medium is not particularly limited, and the thickness of the ink absorbing layer is larger than that of plain paper, high-quality plain paper, inkjet (IJ) paper, IJ matte paper, coated paper in which an ink absorbing solution is coated on the recording medium, and coated paper. Can be used for thin coated paper, glossy paper (photo glossy paper), special paper, cloth, etc.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

<Preparation of resin solution>
50% by mass of each solid resin shown in Table 1 and 50% by mass of methyl oleate (Exepal “M-OL” manufactured by Kao Corporation) are mixed, heated to 120 ° C., dissolved with stirring, Table 2 and Table A resin solution having the composition shown in 3 was obtained. In the resin solution of Example 6, 50% by mass of a mixture of C5 / C9 aliphatic / aromatic hydrocarbon resin A and C5 aliphatic hydrocarbon resin in a mass ratio of 1: 1 was added to methyl oleate 50 Mixed with mass%.

<Ink adjustment>
In each formulation shown in Tables 2 and 3, a pigment, a pigment dispersant, and a non-aqueous solvent were premixed and then dispersed for 4 hours with a rocking mill (manufactured by Seiwa Giken Co., Ltd.) to obtain a pigment dispersion. After mixing the obtained pigment dispersion and the solid resin solution, coarse particles were removed using a cellulose acetate filter (manufactured by Advantech, pore size: 3 μm) to obtain an ink.

The components shown in Tables 2 and 3 are as follows.
Carbon black: MA8, Mitsubishi Chemical Corporation Solsperse 28000: Nippon Lubrizol Corporation AF solvent 6: Petroleum aliphatic hydrocarbon solvent, JX Nippon Mining & Energy Co., Ltd. Isostearyl alcohol: Fineoxocol 180, Nissan Chemical Industry Co., Ltd. Methyl Oleate: Exepal "M-OL", Kao Corporation

<Measurement of acid value of solid resin>
(C5 / C9 aliphatic / aromatic hydrocarbon resin A)
A solid resin and THF (tetrahydrofuran) were mixed and dissolved at a mass ratio of 1: 2 to prepare a resin solution for measurement. Next, 15 g of this measurement resin solution was weighed into a 100 ml Erlenmeyer flask, and several drops of a phenolphthalein solution were added as an indicator. Next, this solution was titrated with a 0.5 mol / l potassium hydroxide ethanol solution using a 10 ml burette, and the end point was when the indicator lightly red for 30 seconds or more. The acid value per gram of the solid resin was determined from the amount of potassium hydroxide required for titration and found to be 17 (mgKOH / g). The reagents used are all manufactured by Wako Pure Chemical Industries.

(Mix ratio of C5 / C9 aliphatic / aromatic hydrocarbon resin A and C5 aliphatic hydrocarbon resin in a mass ratio of 1: 1)
In the method for measuring C5 / C9 aliphatic / aromatic hydrocarbon resin A, the mass ratio of C5 / C9 aliphatic / aromatic hydrocarbon resin A to C5 aliphatic hydrocarbon resin is 1 as the solid resin. The acid value per gram of the solid resin was determined in the same manner except that 30 g of the measurement resin solution was measured in a 100 ml Erlenmeyer flask using the mixture of No. 1 and found to be 9.4 (mg KOH / g). It was.

  The acid values of other solid resins were referred to catalog values.

<Ink viscosity measurement>
The viscosity of the ink is a viscosity at 10 Pa when the shear stress is increased from 0 Pa at a rate of 0.1 Pa / s at 23 ° C., and is a stress-controlled rheometer RS75 (cone angle: 1 °, diameter: 60 mm) manufactured by Harke. It was measured.

<Print density evaluation>
The obtained ink was loaded into an ink jet printer “ORPHIS-X9050” (manufactured by Riso Kagaku Kogyo Co., Ltd.), and a solid image equivalent to 300 dpi was printed on an ideal paper thin mouth (Ritsu Kagaku Kogyo Co., Ltd., plain paper). The surface OD value of the solid image portion of the printed material was measured using an optical densitometer (RD920, manufactured by Macbeth Co.) and evaluated according to the following criteria. The “ORPHISX 9050” is a system that uses a line-type ink jet head and conveys paper in the sub-scanning direction orthogonal to the main scanning direction (the direction in which the nozzles are arranged) to perform printing. The results are shown in Tables 2 and 3.
AA: Surface OD value is 1.15 or more A: Surface OD value is 1.14 to 1.10
B: Surface OD value is 1.05-1.09
C: Surface OD value is 1.04 or less

<Evaluation of back-through prevention effect>
In the same manner as the print density evaluation described above, the back surface OD value of the solid image portion of the obtained printed matter was measured and evaluated according to the following criteria. As the back surface OD value is smaller, the back-through is prevented. A result is combined with Table 2 and Table 3, and A: Back surface OD value is 0.20 or less B: Back surface OD value is 0.21-0.24.
C: Back OD value is 0.25 or more

<Evaluation of transfer dirt prevention effect>
The obtained ink was loaded into ORPHIS-X9050 (manufactured by Riso Kagaku Kogyo Co., Ltd.), and a solid image equivalent to 300 dpi was printed on an ideal paper thin mouth (made by Riso Kagaku Kogyo Co., Ltd., plain paper). The degree of contamination of the non-printed portion of the printed material was visually observed and evaluated according to the following criteria. The results are shown in Tables 2 and 3.
AA: No transfer dirt A: Little transfer dirt B: Some transfer dirt C: Transfer dirt is conspicuous

  As shown in Tables 2 and 3, the inks of the respective examples were excellent in the effect of preventing transfer stains, and were excellent in the printing density and the anti-through-through effect. In Examples 1 to 4, it was found that the same solid resin was used and the blending ratio of the solid resin was different. When the amount of the solid resin was increased, the transfer antifouling action and the printing density were improved. In Embodiment 4, when the amount of the solid resin is 10% by mass or more, the ink viscosity is also increased, so that it is considered that the effect of preventing the transfer stain is lowered. In Examples 3, 5 and 6, it was found that the amount of the solid resin was the same, but the type of the solid resin was different, and the larger the acid value of the solid resin, the better the anti-staining effect.

  In Comparative Example 1, since the solid resin was not included, the printing density and the back-through prevention action were reduced. In Comparative Examples 2 and 3, since the solid resin was not acid-modified, the transfer stain prevention effect was reduced. In Comparative Example 4, since it is not a petroleum-based hydrocarbon resin, the effect of preventing transfer contamination was lowered.

Claims (4)

Look-containing acid modified petroleum hydrocarbon resin, a pigment and non-aqueous solvent, wherein the nonaqueous solvent comprises a petroleum-based solvent and an ester solvent, an inkjet non-aqueous pigment ink.   The non-aqueous pigment ink for inkjet according to claim 1, wherein the acid value of the acid-modified petroleum hydrocarbon resin is 0.5 (mgKOH / g) to 20 (mgKOH / g).   The non-aqueous pigment ink for inkjet according to claim 1 or 2, wherein the acid-modified petroleum hydrocarbon resin has an aromatic hydrocarbon group. The non-aqueous pigment ink for inkjet according to any one of claims 1 to 3 , wherein the non-aqueous solvent further includes an alcohol solvent.