JP2011252057A - Oil-based ink composition for inkjet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil-based ink for inkjet containing a substance that can increase an image density while suppressing the viscosity of ink to low.SOLUTION: The oil-based ink composition for inkjet contains (A) 1-15 mass% of a pigment, (B) 70-95 mass% of a solvent, and (C) a urethanized oil in an amount of 0.3-1.5 in a mass ratio to (A) the pigment.

Description

  The present invention relates to an oil-based ink composition for inkjet printing, and more particularly to an oil-based ink composition that can form a high-density image with low viscosity by including a urethanized oil.

   The ink coloring materials used in inkjet recording systems are broadly divided into those using pigments and those using dyes, but they have excellent light resistance, weather resistance and water resistance necessary for high-quality printing. Therefore, there is a tendency for inks using pigments as color materials to increase. In terms of the solvent, the ink is large and can be divided into a water-based ink and a non-water-based ink. Non-water-based inks that do not use water as the solvent for ink, such as solvent-based inks mainly composed of volatile solvents and oil-based inks mainly composed of non-volatile solvents, have better drying properties and printability than water-based inks. Is also excellent. In non-aqueous type inks, a pigment dispersant that dissolves in a solvent is generally used. This pigment dispersant enhances the affinity between the solvent and the pigment. Therefore, when the solvent penetrates into the recording paper, the pigment also enters the recording paper. There is a tendency to be drawn. As a result, the print density is lowered and the showthrough is likely to occur. Therefore, a non-aqueous pigment ink using a non-aqueous resin dispersed fine particle (NAD = Non Aqua Dispersion) having a pigment dispersing ability as a dispersant has been proposed (Patent Document 1).

  A urethane-modified poly (meth) acrylate resin obtained by improving the above resin in terms of pigment dispersibility is also known (Patent Document 2). When the resin is blended, an ink that is excellent in storage stability and forms a high-density image can be formed without using a pigment dispersant that dissolves in a solvent.

JP 2007-197500 A JP 2010-1452 A

  However, it has been found that when the urethane-modified poly (meth) acrylate resin is blended, the viscosity of the ink tends to increase. For this reason, when adjusting the viscosity of the ink to a desired range, there is a problem that the types and amounts of other components such as pigments, solvents, additives and the like to be blended are limited, and the degree of freedom in design is limited. .

  Therefore, an object of the present invention is to provide an oil-based ink for ink jetting containing a substance capable of increasing the image density while keeping the viscosity of the ink low.

That is, this invention is the oil-based ink composition for inkjets containing the following.
(A) Pigment 1 to 15% by mass
(B) 70-95 mass% of solvent
(C) Urethane oil (A) The quantity whose mass ratio with respect to a pigment is 0.3-1.5.

  The urethanized oil hardly increases the viscosity of the ink by blending and is excellent in pigment dispersibility. Therefore, it can be used in place of the urethane-modified poly (meth) acrylate resin or in combination with a part of the urethane-modified poly (meth) acrylate resin.

Hereafter, each said component is demonstrated.
<(C) Urethane oil>
The urethanized oil used in the oil-based ink composition of the present invention (hereinafter simply referred to as “ink”) is an alcoholic product obtained by transesterifying a fat and oil selected from a drying oil, a semi-drying oil and a non-drying oil with a polyhydric alcohol. A diglyceride or monoglyceride having a hydroxyl group is prepared and reacted with an organic isocyanate compound.

  Dry oil, semi-dry oil, non-dry oil include soybean oil, palm oil, linseed oil, rice oil, tung oil, safflower oil, safflower oil, cacao butter, castor oil and palm oil, natural oils, synthetic fats and oils, Boil oil and dehydrated castor oil can be used, and among these, soybean oil, coconut oil, linseed oil, cocoa butter and palm oil are preferable, and soybean oil and coconut are preferred in terms of ink stability (oxidation resistance). Oil is more preferred.

  As the polyhydric alcohol, glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol and dipropylene glycol, trimethylolpropane, pentaerythritol and the like are used.

  As the organic isocyanate compound, aromatic diisocyanates such as phenylene diisocyanate, tolylene diisocyanate and naphthylene diisocyanate, aliphatic diisocyanates such as tetramethylene diisocyanate and hexamethylene diisocyanate are used, preferably tolylene diisocyanate or hexamethylene diisocyanate is used. Is done.

  Preferably, the urethanized oil contains a diglyceride or monoglyceride residue of a fatty acid having 6 to 20 carbon atoms, preferably 8 to 20, more preferably 10 to 20, and an oil length of 50 to 95% by mass, more preferably. Is 50-70 mass%. Here, the oil length is a mass (%) obtained by converting the mass of the fatty acid residue contained in the urethanized oil into triglyceride.

  The urethanized oil preferably has a viscosity (mPa · s) of 500 to 2000, more preferably 750 to 1500. If the viscosity is less than the lower limit, the pigment dispersibility tends to be low, whereas if the viscosity exceeds the upper limit, the viscosity of the ink tends to increase.

  The urethanized oil is blended in the ink in an amount such that the mass ratio to the pigment (A) is 0.3 to 1.5, more preferably 0.5 to 1.0. If the blending amount is less than the lower limit value, the dispersion of the pigment becomes insufficient. On the other hand, if the blending amount exceeds the upper limit value, it becomes difficult to prepare an ink having an appropriate viscosity for ink jet printing.

<(A) Pigment>
In the ink of the present invention, the pigment may be arbitrary. As the pigment for black ink, carbon black such as furnace black, channel black, oil smoke, or pine smoke black can be used.

  Examples of color ink pigments include magenta pigments such as 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 Parared, 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 Rake, Anthosine 5B rake, Rhodamine 6G rake, Eosin rake, Bengala, Faftol Red GR, rhodamine B lake, methyl bio red lake, dioxazine bio red, naphthol carmine FB, naphthol red M, etc .; yellow pigments such as fast yellow AAA, fast yellow 10G, disazo yellow AAMX, disazo yellow AAOT, disazo yellow AAOA, disazo Yellow HR, isoindoline yellow, fast yellow G, disazo yellow AAA, cyan pigments such as phthalocyanine blue, pictoria pure blue, basic blue 5B lake, basic blue 6G lake, fast sky blue, alkali blue R toner, peacock blue lake , Bitumen, ultramarine, reflex blue 2G, reflex blue R, alkali blue G toner, brilliant green lake, da A Monde green thioflavin lake, phthalocyanine green G, green gold, the phthalocyanine green Y or the like can be used.

  Among these pigments, yellow pigments, particularly azo yellow and benzimidazolone yellow, and cyan pigments, particularly phthalocyanine blue, are more remarkably improved in dispersibility by the urethane-modified oil.

  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 can be measured by a dynamic light scattering particle size distribution analyzer LB-500 manufactured by Horiba, Ltd.

  The pigment is blended in the ink in an amount of 1 to 15% by mass, preferably 5 to 10% by mass.

<(B) Solvent>
As the solvent, a nonpolar organic solvent, a polar organic solvent, or a mixture thereof can be used. It is preferable that 20-60 mass% nonpolar solvent and 80-40 mass% polar solvent are mix | blended.

  Examples of the nonpolar organic solvent include aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, aromatic hydrocarbon solvents, and the like. Examples of the aliphatic hydrocarbon solvent and alicyclic hydrocarbon solvent include paraffinic, isoparaffinic and naphthenic solvents. For example, what is sold with the following brand names is mentioned. Teclean N-16, Teclean N-20, Teclean N-22, Nisseki Naphthezol L, Nisseki Naphthezol 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, and AF-7 (all manufactured by Nippon Oil Corporation); Isopar G, Isopar H, Isopar L, Isopar M, Exxol D40, Exxol D80, Exxol D100 , ExxolD130, and ExxolD140 (all manufactured by Exxon). Examples of the aromatic hydrocarbon solvent include Nippon Oil Clean Sol G (alkylbenzene) manufactured by Nippon Oil Corporation and Solvesso 200 manufactured by Exxon. Of these, naphthenic solvents, AF-4, AF-5, AF-6, and AF-7 (trade names) are preferred.

  As the polar organic solvent, ester solvents, alcohol solvents, higher fatty acid solvents, and ether solvents can be used. Examples of ester solvents include methyl laurate, isopropyl laurate, hexyl laurate, isopropyl myristate, isopropyl palmitate, isooctyl 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, tri-2-ethyl Examples include trimethylolpropane hexanoate and glyceryl tri-2-ethylhexanoate, and two or more of these solvents can be mixed and used. Preferably, isooctyl palmitate, hexyl laurate, or octyl caprate is used.

  Examples of alcohol solvents include isomyristyl alcohol, isopalmityl alcohol, isostearyl alcohol, and oleyl alcohol; examples of higher fatty acid solvents include isononanoic acid, isomyristic acid, hexadecanoic acid, isopalmitic acid, oleic acid, and isostearic acid; ether solvents Examples thereof include diethyl glycol monobutyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, and propylene glycol dibutyl ether. Of these, ester solvents, alcohol solvents and mixtures thereof are preferred.

<Other ingredients>
In addition to the above components, the ink of the present invention may contain conventional additives. Such additives include conventional pigment dispersants, synergists, surfactants such as anionic, cationic, amphoteric or nonionic surfactants and antioxidants such as dibutylhydroxytoluene, propyl gallate, Tocopherol, butylhydroxyanisole, nordihydroguaiaretic acid, and the like.

  Examples of the pigment dispersant include a hydroxyl group-containing carboxylic acid ester, a salt of a long chain polyaminoamide and a high molecular weight acid ester, a salt of a high molecular weight polycarboxylic acid, a salt of a long chain polyaminoamide and a polar acid ester, and a high molecular weight unsaturated. Acid ester, modified polyurethane, modified polyacrylate, polyether ester type anionic activator, naphthalene sulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphate ester, polyoxyethylene nonyl phenyl ether, polyester polyamine, stearylamine acetate, etc. Can be mentioned.

  Preferred for use in combination with the (C) urethanized oil in the present invention is a polymeric dispersant, such as those sold under the following trade names: Solsperse 5000 (phthalocyanine ammonium salt type), 11200 (polyamide series), 13940 (polyesteramine series), 17000, 18000 (fatty acid amine series), 22000, 24000, and 28000 (all manufactured by Nihon Lubrizol); Fuka 400, 401, 402, 403, 450, 451 , 453 (modified polyacrylate), 46, 47, 48, 49, 4010, and 4055 (modified polyurethane) (all manufactured by Efka CHEMICALS); demole P, EP, poise 520, 521, 530, and homogenol L-18 (Polycarboxylic acid type polymer surface activity Agent) (all manufactured by Kao Corporation); Disparon KS-860, KS-873N4 (amine salt of high molecular polyester) (all manufactured by Enomoto Kasei Co., Ltd.); Discall 202, 206, OA-202, and OA- 600 (multi-chain polymer nonionic) (both manufactured by Daiichi Kogyo Seiyaku Co., Ltd.); ANTARON V216 (vinyl pyrrolidone-hexadecene copolymer) (manufactured by IPS Japan Co., Ltd.).

  The synergist is a derivative in which a polar group is introduced into the pigment skeleton, and improves the dispersibility of the pigment by being adsorbed on the pigment. Examples of pigment skeletons include azo pigments, phthalocyanine pigments, quinacridone pigments, perylene pigments, isoindoline pigments, benzimidazolone pigments, pyranthrone pigments, thioindigo pigments, and quinophthalone pigments. Examples of the polar group include an alkylamino group, a carboxyl group, a sulfonic acid group, and a phthalimide group. Among these, phthalocyanine pigments, particularly those obtained by introducing a sulfonic acid group, an amino group or the like into the skeleton of copper phthalocyanine blue, for example, copper phthalocyanine sulfonate (Solsperse 5000, Solsperse 12000, Solsperse 22000; all manufactured by Lubrizol) are preferable. Can be mentioned.

  Further, a urethane-modified poly (meth) acrylate resin (Patent Document 2) may be used in combination with (C) urethanized oil as long as the object of the present invention is not impaired. The urethane-modified poly (meth) acrylate resin is preferably blended in such an amount that the mass ratio to (C) urethanized oil is 0.1-1. The ink viscosity can be kept lower than when the acrylate resin is blended alone.

  The ink of the present invention can be prepared by charging the above-mentioned components into a dispersing machine such as a bead mill in a batch or divided, stirring, mixing, and filtering through a membrane filter or the like as desired.

  The appropriate range of the viscosity of the ink varies depending on the nozzle diameter of the discharge head of the inkjet printer and the discharge environment, but generally it is preferably 5 to 30 mPa · s at 23 ° C., more preferably 5 to 15 mPa · s. . The viscosity is a value at 10 Pa when the shear stress is increased from 0 Pa to 0.1 Pa / s.

  The ink jet printer may be of any system such as a piezo system, an electrostatic system, or a thermal system.

[Examples 1-5, Comparative Examples 1-3]
Each component was put into a 250 ml polypropylene container according to the formulation (mass%) shown in Table 1, and dispersed with a rocking mill (Seiwa Giken Co., Ltd.) for 120 minutes using 450 g of zirconia beads (diameter 0.5 mm). The obtained mixture was filtered through a 3.0 μm membrane filter to obtain each ink composition. In addition, the numerical value of Table 1 is the quantity of solid content.

The detail of each component of Table 1 is as follows.
Cyan pigment: Phthalocyanine blue (PB15: 4), Sanyo Dye Co., Ltd. Yellow pigment: Azo yellow (pigment yellow 14), Dainichi Seika Kogyo Co., Ltd. Urethane oil 1: Urethane palm oil (non-volatile content 50%) )
Urethane oil 2: Urethane soybean oil (non-volatile content 50%)
Urethane oil 3: Urethane linseed oil (non-volatile content 50%)
Synergist: Solsperse 5000, manufactured by Lubrizol Other dispersant 1: Solsperse 11200, solid content in aliphatic solvent 50% by mass (the blended amount in Table 1 is the solid content), Nippon Lubrizol Co., Ltd. Isomyristyl alcohol: FOC140N , Manufactured by Nissan Chemical Industries, Ltd. Naphthenic solvent: AF-6, manufactured by Nippon Oil Corporation

The other dispersant 2 is a urethane-modified poly (meth) acrylate resin, and was prepared by the following method in the same manner as Example 18 described in JP2010-1452A.
(1) Synthesis of main chain A 300 ml four-necked flask was charged with 75 g of AF-4 (naphthenic solvent; manufactured by Nippon Oil Corporation) and heated to 110 ° C. while aerated with nitrogen gas and stirred. . Subsequently, 16.7 g of AF-4 was added to a mixture of 50% by weight of behenyl methacrylate, 3515% by weight of 2-ethylhexyl methacrylate, 20% by weight of 2-acetoacetoxyethyl methacrylate, and 15% by weight of glycidyl methacrylate while maintaining the temperature at 110 ° C. A mixture of 2 g of O (t-butylperoxy 2-ethylhexanoate; manufactured by NOF Corporation) was added dropwise over 3 hours. Thereafter, 0.2 g of perbutyl O was added after 1 hour and 2 hours while maintaining at 110 ° C. Furthermore, after aging at 110 ° C. for 1 hour, it was diluted with 10.4 g of AF-4 to obtain a colorless and transparent main chain polymer solution having a nonvolatile content of 50%. The weight average molecular weight (GPC method, standard polystyrene conversion) of the obtained polymer was 20000-23000.
(2) Synthesis of urethane bond part In a 500 mL four-necked flask, 81 g of isooctyl palmitate (IOP, manufactured by Nikko Chemicals Co., Ltd.), the polymer solution obtained in (1) above (solid content 50 in AF-4 solvent) %) 200 g, propylene glycol 4.0 g, and diethanolamine 2.8 g were charged, and the temperature was raised to 110 ° C. while aerated and stirred with nitrogen gas, and kept at that temperature for 1 hour. Thereafter, 0.2 g of dibutyltin dilaurate was added, and a mixture of Takenate 600 (1,3-bis (isocyanatomethyl) cyclohexane, Mitsui Chemicals Polyurethane Co., Ltd.) 10.2 g and IOP 99 91.8 g was added for 1 hour. It was dripped over. After the dropping, the temperature was raised to 120 ° C. and reacted for 6 hours, followed by cooling to obtain a resin dispersion having a solid content of 30%. The weight average molecular weight (GPC method, standard polystyrene conversion) of the obtained polymer was 22000-26000.

Each ink composition obtained (however, in Comparative Example 3 only the viscosity) was evaluated by the following method.
<Viscosity>
The viscosity of the composition at room temperature was measured at 23 ° C. at 10 Pa using RS300 manufactured by Haake.

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<Image density>
Each ink was loaded into an ink jet recording apparatus “HC5500” (Riso Kagaku Kogyo Co., Ltd.), and the voltage was set so that 42 pl was discharged with 7 drops. Print a solid image on plain paper (ideal thin paper) with cyan at a resolution of 300 dpi x 300 dpi (7 drops per dot) and yellow at a resolution of 150 dpi x 300 dpi (7 drops per dot). The OD value was measured with a Macbeth densitometer (RD920 manufactured by Macbeth Co.) and evaluated according to the following criteria.

Cyan (Resolution: 300 x 300 dpi)

Yellow (resolution: 150 x 300 dpi)

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<Back-through>
The OD value of the back surface of the solid image was measured in the same manner as described above, and evaluated according to the following criteria.

Cyan (Resolution: 300 x 300 dpi)

Yellow (Resolution: 150 x 300 dpi)

In order to investigate the dependency on the printing paper of the OD value and the back-through, using the inks of Example 4 and Comparative Example 2, in addition to the plain paper, a solid image was similarly printed on the following three types of paper, OD value and strike-through were measured. The results are shown in Table 2. In Table 2, the paper 1 is the ideal paper thin mouth.
Paper 1: Ideal paper thin paper, plain paper made by Riso Science Co., Ltd. Paper 2: RISO HC paper IJ, plain paper made by Riso Kagaku Co., Ltd. Paper 3: Asukul Multipaper Super Select Smooth, ASKUL plain paper Paper 4: WHITE PPC, KOKUYO Plain paper

<Storage stability>
About 20 g of the composition was put in a 50 ml glass bottle and the viscosity after being left in an oven at 70 ° C. for 1 week was measured by the above-mentioned method, the rate of change from the initial viscosity was determined, and evaluated according to the following criteria.

  As shown in Table 1, the ink of the present invention has a higher image density and less show-through than the ink containing a general-purpose dispersant (Comparative Examples 1 and 2). As can be seen from Table 2, the ink of the present invention exhibits a high image density without depending on the type of plain paper. The ink of the present invention can keep the ink viscosity low compared to a general-purpose dispersant (Comparative Example 2) and also to an ink containing a urethane-modified poly (meth) acrylate resin (Comparative Example 3). I understand that I can do it.

  By including the urethanized oil, the ink composition of the present invention can form an image having a high density while having a low viscosity. By using the urethanized oil, the degree of freedom in designing the ink formulation is increased.

Claims (6)

Ink-jet oil-based ink composition comprising: (A) Pigment 1 to 15% by mass
(B) 70-95 mass% of solvent
(C) Urethane oil (A) The quantity whose mass ratio with respect to a pigment is 0.3-1.5. (C) The oil-based ink composition for inkjets of Claim 1 in which a urethanized oil contains the diglyceride or triglyceride residue of a C6-C20 fatty acid, and has an oil length of 50-95 mass%. (C) Urethane oil is produced by transesterifying fats and oils with polyhydric alcohol and then reacting with diisocyanate, and the fats and oils are linseed oil, soybean oil, coconut oil, cocoa butter, and palm. The oil-based ink composition for inkjet according to claim 1 or 2, which is at least one selected from the group consisting of oils. The oil-based ink composition for inkjet according to claim 3, wherein the fat is at least one selected from soybean oil and coconut oil. (A) The oil-based ink composition for inkjets of any one of Claims 1-4 whose pigment is a yellow pigment. (A) The oil-based ink composition for inkjets of any one of Claims 1-4 whose pigment is a cyan pigment.