JP2010059364A - Ink composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pigment ink composition for inkjet recording, with which excellent printing stability, printed matter durability, and drying characteristics are achieved. <P>SOLUTION: The ink composition at least includes a pigment, an organic solvent, and two or more binder resins with their weight average molecular weights (Mw) different from each other, wherein general expressions (1), (2) are satisfied when the weight average molecular weight of the binder resin with the minimum weight average molecular weight (Mw) out of two or more used binder resins is represented by Mwα, and that of the binder resin with a larger weight average molecular weight (Mw) is represented by Mwβx (x=1, 2, 3, and so on). General expression (1): Mwβx (x=1, 2, 3, and so on)-Mwα≥10,000. General expression (2): 1,000<Mwα<30,000 and 20,000<Mwβx<100,000. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pigment ink composition capable of realizing excellent printing stability, printed matter performance, and drying property.

  Conventionally, gravure printing for soft packaging materials, flexographic printing for sanitary, silk screen printing for metal plates, inkjet printing for indoor and outdoor advertising, etc. are generally known as printing methods for non-absorbent substrates.

  In particular, in inkjet printing that prints images and characters using minute ink droplets ejected from the nozzles of an inkjet head, inkjet printers that can handle A-0 size have been developed in recent years for outdoor applications such as outdoor posters. Ink jet printing inks that are excellent in water resistance, weather resistance, and friction resistance have been actively developed against the background of the increase in usage environment.

  In particular, ink-jet printing inks used for the sign industry are mainly solvent ink-jet inks that use organic solvents as the solvent, instead of water-based ink-jet inks in which colorants such as water-soluble dyes are added to general water. in use. For example, for printing on the surface of a polyvinyl chloride sheet or the like that is used as a medium for outdoor advertising, etc., a pigment excellent in weather resistance, a binder resin that firmly adheres the pigment to the sheet surface, A pigment ink composition containing an organic solvent capable of dissolving the binder resin is considered suitable.

In particular, when selecting a binder resin, it is common to select one of various types of resin so that it can be stably ejected from an inkjet head and sufficient printed material resistance and drying properties can be realized. (Patent Documents 1 to 3). However, if a resin that improves the ejection stability from the ink jet head is selected, the coating film resistance and drying properties deteriorate, and if a resin that improves the coating film resistance and drying properties is selected, the ejection stability deteriorates. Therefore, it has been difficult to develop an ink-jet ink that improves all the performance.
JP 2007-284642 A JP 2006-56990 A JP 2007-169492 A

  The present invention has been made in view of the above problems, and its purpose is to provide a pigment ink composition, particularly an inkjet ink composition, that can achieve excellent printing stability, printed matter resistance, and drying properties. is there.

  That is, the present invention includes at least a pigment, an organic solvent, and two or more types of binder resins having different weight average molecular weights (Mw), and the binder having the smallest weight average molecular weight (Mw) among the two or more types of binder resins used. An ink composition characterized by satisfying the general formulas (1) and (2) when a resin is Mwα and a binder resin having a large weight average molecular weight (Mw) is Mwβx (x = 1, 2, 3...). Related to things.

General formula (1): Mwβx (x = 1, 2, 3...) −Mwα ≧ 10,000
General formula (2): 1,000 <Mwα <30,000 and 20,000 <Mwβx
<100,000

Furthermore, the present invention relates to the above ink composition, wherein the relationship between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the two or more kinds of binder resins contained is in the following range.
1 <Mw / Mn <3

  Furthermore, the present invention relates to the above ink composition, wherein the two or more kinds of binder resins contained are a vinyl chloride resin and / or an acrylic resin.

Furthermore, the present invention relates to the above ink composition characterized in that it contains any one or more of the solvents represented by formulas (a) to (d) as an organic solvent.
R ₁ CO (OR ₂ ) _Z OR ₃ (a) R ₄ CO (OR ₅ ) _Z OCOR ₆ (b)
R ₇ (OR ₈ ) _Z OR ₉ (c) R ₁₀ COOR ₁₁ (d)
(Wherein R _2, R _{5 and} R ₈ are each independently an ethylene group or a propylene group, R ₁ , R ₃ ,
R ₄ and R ₆ are each independently an alkyl group having 1 to 4 carbon atoms, R ₇ and R ₉ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ₁₀ is a 2-hydroxyethyl group, R ₁₁ represents an alkyl group having 1 to 8 carbon atoms, Z is an integer of 1-3. )

Furthermore, the present invention relates to the above ink composition, wherein a part of the organic solvent contains a nitrogen-containing, sulfur-containing or lactone-based solvent.
Furthermore, the present invention relates to the above ink composition, wherein the ink composition contains a dispersant.
Furthermore, this invention relates to the said ink composition which is an inkjet ink.

  According to the present invention, by using two or more binder resins having different weight average molecular weights (Mw) in the ink, a pigment ink composition capable of realizing excellent printing stability, printed matter performance, and drying property, In particular, an inkjet ink composition is provided.

Hereinafter, the best mode for carrying out the present invention will be described.
The ink composition of the present invention comprises a pigment ink composition comprising a pigment having excellent weather resistance, a binder resin for firmly adhering the pigment to the surface of a print medium, and an organic solvent capable of dissolving the binder resin. It is. Examples of the binder resin having excellent adhesion to the print medium surface include acrylic resins, styrene-acrylic resins, styrene-maleic resins, rosin resins, rosin ester resins, ethylene-vinyl acetate resins, petroleum Resin, coumarone indene resin, terpene phenol resin, phenol resin, urethane resin, melamine resin, urea resin, epoxy resin, cellulose resin, xylene resin, alkyd resin, aliphatic hydrocarbon resin, butyral resin, maleic acid Resin, fumaric acid resin, vinyl chloride resin and the like can be used. Specific examples of the resin include BR-50, BR-52, MB-2539, BR-60, BR-64, BR-73, BR-75, MB-2389, BR-80, BR- manufactured by Mitsubishi Rayon Co., Ltd. 83, BR-87, BR-105, BR-106, BR-107, BR-110, BR-113, MB-2660, MB-2952, MB-3015, MB-7033, BR-115, MB-2478, BR-116, Wilber Ellis A-12, A-21, B-38, B-60, B-65, B-66, B-67, B-99N, DM-55, manufactured by Dow Chemicals Yuker Solution vinyl resins VYHD, VYHH, VMCA, VROH, VYLF-X, Nissin Chemical Industry's sorbine resins CL, CNL, C5R, TA3, TA5R, manufactured by Wacker Nyl resin E15 / 45, H14 / 36, H40 / 43, E15 / 45M, E15 / 40M, Superester 75 manufactured by Arakawa Chemical Co., Ltd., Ester Gum HP, Malkid 33, YS Polyster T80 manufactured by Yasuhara Co., manufactured by Mitsui Chemicals, Inc. HIRETTS HRT200X, Jonkrill 586 manufactured by Johnson Polymer Co., Ltd., and SMA 2625P manufactured by Sartomer Co.

  The resin is preferably contained in the ink in an amount of 0.1 to 20% by weight. When the addition amount is 0.1% by weight or less in the ink, the adhesion to the surface of the printing medium is poor, and the resistance of the coating film is reduced. When the addition amount is 20% by weight or more, the ink viscosity is too high, and thus the printability is high. Since it falls, it is not preferable. An acrylic resin, a styrene-acrylic resin, and a vinyl chloride resin are preferable from the point of resistance of printed matter, and an acrylic resin and a styrene-acrylic resin are more preferable from the viewpoint of drying property.

However, the resin used as the binder resin has good printed matter resistance and drying properties when the weight average molecular weight (Mw) is large, but is the most important performance as an inkjet ink, and has the ink ejection stability from the inkjet head. It will get worse. On the other hand, when the weight average molecular weight (Mw) of the binder resin is small, the discharge stability is good, but the printed matter resistance and drying property are deteriorated. For this reason, it has been difficult to develop an ink-jet ink that improves all three of these performances.
Therefore, as a result of various studies, the present inventors have realized that excellent printing stability, printed matter performance, and drying property can be achieved by using two or more types of binder resins having different weight average molecular weights (Mw). Knowing that a pigment ink composition for inkjet recording can be produced, the present invention has been completed.

  In the present invention, two or more kinds of binder resins having different weight average molecular weights (Mw) are used in order to produce a pigment ink composition for inkjet recording capable of realizing excellent printing stability, printed matter resistance, and drying property. . Two or more kinds of binder resins to be used are binder resin Mwα having the smallest weight average molecular weight (Mw) and binder resin Mwβx (x = 1, 2, 3...) Having a weight average molecular weight (Mw) larger than Mwα. It is preferable to contain one or more types. The combination of a small binder resin (Mwα) that excels in ink ejection stability and a large binder resin (Mwβx) that excels in print performance and drying properties can improve all three of these performances. Is the purpose.

  The relationship between the weight average molecular weights (Mw) of two or more binder resins used in the present invention is preferably Mwβx−Mwα ≧ 10,000, more preferably Mwβx−Mwα ≧ 15,000, and further Mwβx -Mwα ≥ 20,000 is particularly preferred. If the relationship between the weight average molecular weights (Mw) of two or more types of binder resins used is in the range of Mwβx-Mwα ≧ 20,000, it is possible to produce an ink having excellent ejection stability, printed material performance, and drying properties. In the region where Mwβx−Mwα <10,000, it is difficult to improve all three performances.

  The relationship between the weight average molecular weights (Mw) of two or more binder resins is preferably in the range of 1,000 <Mwα <30,000 and 20,000 <Mwβx <100,000. The region of 000 <Mwα <30,000 and 20,000 <Mwβx <50,000 is particularly preferred. When Mwα <1,000, the printed film becomes brittle and cracks when printed, and when Mwα> 30,000, the discharge stability deteriorates. Further, when Mwβx <20,000, excellent printed material performance / drying property cannot be realized, and when Mwβx> 100,000, the ink jet head cannot be ejected.

  The relationship between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the two or more binder resins is preferably in the region of 1 <Mw / Mn <3, more preferably 1 <Mw / Mn <2. .5, and a region of 1 <Mw / Mn <2.3 is particularly preferable. When the relationship between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of two or more binder resins is in the region of 1 <Mw / Mn <2.3, the ink is easily dissolved in a solvent and stable in ejecting ink from an inkjet head. In the region where Mw / Mn> 3, the binder resin is difficult to dissolve in the solvent, so that the ink ejection stability is deteriorated.

  Moreover, a vinyl chloride resin and / or an acrylic resin can be used for two or more types of binder resin contained. By using a vinyl chloride resin that is excellent in printed gloss and film stretchability and an acrylic resin that is excellent in drying properties of the printed material, it is excellent in printed matter without show-through (blocking) even in an inkjet printer with a high printing speed. Can be obtained.

  The main solvent used in the present invention is preferably one having a boiling point of 150 ° C. or higher. If the boiling point is too low, drying on the nozzles is accelerated when used as an inkjet ink, causing clogging. Further, the flash point is preferably 61 ° C. or higher. If the flash point is less than 61 ° C, it is classified as a highly flammable liquid in dangerous goods in the case of ship transportation under international transport laws and regulations, and is restricted during transportation and transportation. More preferably, the flash point is 70 ° C. or higher. When the temperature exceeds 70 ° C., it is classified as a hazardous material type 4 and type 3 petroleum under the Fire Service Law, and restrictions on manufacturing, transportation, transportation and storage are reduced.

As such a solvent, there are solvents represented by the following general formulas (a) to (d).
R ₁ CO (OR ₂ ) _Z OR ₃ (a) R ₄ CO (OR ₅ ) _Z OCOR ₆ (b)
R ₇ (OR ₈ ) _Z OR ₉ (c) R ₁₀ COOR ₁₁ (d)
_{(Wherein, R 2, R 5, R} 8, each independently represents an ethylene group or a propylene _group, R _{1, R} 3,
R ₄ and R ₆ are each independently an alkyl group having 1 to 4 carbon atoms, R ₇ and R ₉ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ₁₀ is a 2-hydroxyethyl group, R ₁₁ represents an alkyl group having 1 to 8 carbon atoms, and Z represents an integer of 1 to 4. )

  Solvents corresponding to general formula (a) include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl. Ether acetate, dipropylene glycol monomethyl ether acetate, ethylene glycol monomethyl ether propionate, ethylene glycol monoethyl ether propionate, ethylene glycol monobutyl ether propionate, diethylene glycol monomethyl ether propionate, diethylene glycol mono Chill ether propionate, diethylene glycol monobutyl ether propionate, propylene glycol monomethyl ether propionate, dipropylene glycol monomethyl ether propionate, ethylene glycol monomethyl ether butyrate, ethylene glycol monoethyl ether butyrate, ethylene glycol monobutyl ether butyrate There are glycol monoacetates such as rate, diethylene glycol monomethyl ether butyrate, diethylene glycol monoethyl ether butyrate, diethylene glycol monobutyl ether butyrate, propylene glycol monomethyl ether butyrate and dipropylene glycol monomethyl ether butyrate.

  Solvents corresponding to the general formula (b) include ethylene glycol diacetate, diethylene glycol diacetate, propylene glycol diacetate, dipropylene glycol diacetate, ethylene glycol acetate propionate, ethylene glycol acetate butyrate, ethylene glycol propionate. Butyrate, ethylene glycol dipropionate, ethylene glycol dibutyrate, diethylene glycol acetate propionate, diethylene glycol butyrate, diethylene glycol propionate butyrate, diethylene glycol dipropionate, diethylene glycol dibutyrate, propylene glycol acetate propionate, propylene glycol acetate Butyrate, propylene glycol Propionate butyrate, propylene glycol dipropionate, propylene glycol dibutyrate, dipropylene glycol acetate propionate, dipropylene glycol acetate butyrate, dipropylene glycol propionate butyrate, dipropylene glycol dipropionate, There are glycol diacetates such as dipropylene glycol dibutyrate.

  Solvents corresponding to the general formula (c) include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol and dipropylene glycol, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, diethylene glycol monoethyl. Ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether, propylene glycol n-propyl ether, triethylene glycol Monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tetraethylene glycol dimethyl ether, there is a glycol ether such as tetraethylene glycol diethyl ether.

Examples of the solvent corresponding to the general formula (d) include esters such as methyl lactate, ethyl lactate, propyl lactate, and butyl lactate.
Of these, (poly) ethylene glycol diether solvents and (poly) ethylene glycol monoether monoester solvents are preferred from the viewpoints of resin solubility and drying properties on the nozzle. Specific examples include ethylene glycol monobutyl ether acetate and diethylene glycol diethyl ether. Diethylene glycol diethyl ether is particularly preferred from the viewpoint of low odor.

  In consideration of safety and health, it is particularly preferable to use diethylene glycol diethyl ether, and from the viewpoint of harmfulness such as acute toxicity, mutagenicity, carcinogenicity, and reproductive toxicity.

    Further, in addition to the general formulas (a) to (d), which are organic solvents in the present invention, the addition of a nitrogen-containing, sulfur-containing or lactone-based solvent can dissolve the surface of the printing medium, so that the fixability , Weather resistance and the like can be improved. Examples include 3-methyloxazolidinone, 3-ethyloxazolidinone, dimethyl sulfoxide, 1-methyl-2-pyrrolidone, γ-butyrolactone, ε-caprolactone, and the like. The addition amount is preferably 1 to 20%, preferably 1 to 10%, more preferably 3 to 9%. If these nitrogen-containing or lactone-based solvents are used excessively, problems are caused from the viewpoint of erosion to the printer member, which is not preferable.

  Examples of the printing medium of the present invention include a polyvinyl chloride resin sheet, a polyolefin-based sheet, glass, metal and the like, and a polyvinyl chloride resin sheet is particularly preferable.

  As the pigment used in the present invention, various pigments used in printing inks, paints and the like can be used. When these pigments are represented by color index, Pigment Black 7, Pigment Blue 15, 15: 1, 15: 3, 15: 4, 15: 6, 60, Pigment Green 7, 36, Pigment Red 9, 48, 49 , 52, 53, 57, 97, 122, 149, 168, 177, 178, 179, 206, 207, 209, 242, 254, 255, pigment violet 19, 23, 29, 30, 37, 40, 50, pigment Yellow 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 94, 95, 109, 110, 117, 120, 125, 128, 137, 138, 139, 147, 148, 150, 151 , 154, 155, 166, 168, 180, 185, 213, Pigment Orange 36, 43, 51, 5 , Such as 59,61,71,74, and the like. As for carbon black, any carbon black such as neutral, acidic and basic can be used. The pigment is desirably contained in the ink in an amount of 0.1 to 10% by weight.

  In the present invention, it is preferable to add a dispersant in order to improve the dispersibility of the pigment and the storage stability of the ink. Examples of the 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, a high molecular weight unsaturated acid ester, Molecular copolymer, modified polyurethane, modified polyacrylate, polyether ester type anionic activator, naphthalene sulfonic acid formalin condensate salt, aromatic sulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphate ester, polyoxyethylene nonyl Phenyl ether, stearylamine acetate, etc. can be used. Since the pigment is dispersed and stabilized by the interaction with the dispersant, it is preferable to use a pigment containing a basic group which is a pigment adsorption site, and a basic containing at least one of a primary amine or a secondary amine. More preferably, a dispersant is used. Of these, polyester-based basic dispersants and acrylic urethane urea-based basic dispersants are most preferable from the viewpoints of solubility in solvents and storage stability of the dispersion.

  Specific examples of the basic dispersant include Solspurs 11200, Solspurs 13240, Solspers 16000, Solspers 18000, Solspers 20000, Solspurs 26000, Solspers 28000, Solspers 31845, Solspers 32500, Solspers 32550, Solspers 32600, Solspers 33000, manufactured by Lubrizol. Sol Spurs 34750, Sol Spurs 35100, Sol Spurs 35200, Sol Spurs 37500, Sol Spurs 38500, Sol Spurs 39000, and Sol Spurs 53095. Specific examples of the polyester-based basic dispersant include Solspers 13940, 17000, 24000, and 32000 manufactured by Lubrizol, and Ajisper PB821, PB822, PB823, PB824, and PB827 manufactured by Ajinomoto Fine-Techno. These can be used according to the kind of pigment and solvent. The dispersant is preferably contained in the ink in an amount of 0.1 to 10% by weight.

  The ink composition of the present invention can use various additives such as a plasticizer, a surface conditioner, an ultraviolet light inhibitor, a light stabilizer, an antioxidant, and a hydrolysis inhibitor.

  Examples of the printing method of the ink composition of the present invention include gravure printing, flexographic printing, silk screen printing, inkjet printing, and the like, and an inkjet printing method is particularly preferable.

  The ink composition of the present invention is prepared by first dispersing a pigment in a single or mixed solvent with a resin or a dispersant using a paint shaker, sand mill, roll mill, medialess disperser, etc. It is manufactured by diluting with the solvent of the invention.

[Example]
EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not particularly limited to the examples. In the examples, “part” represents “part by weight”. In addition, the weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured using a TSKgelsuper HZM-N column (manufactured by Tosoh Corp.) in duplicate and a flow rate of 0.35 ml / GPC (Tosoh Corp., HLC-8220GPC). min. And the molecular weight in terms of polystyrene when THF is used as the developing solvent.

[Production Example 1]
(Production of vinyl polymer: A-1)
A reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer was charged with 500 parts of methyl methacrylate, 18.5 parts of thioglycerol, and 518.5 parts of diethylene glycol diethyl ether (DEDG) and replaced with nitrogen gas. The inside of the reaction vessel was heated to 90 ° C., and 0.50 part of AIBN was added, followed by reaction for 7 hours.
Diethylene glycol diethyl ether (DEDG) was added to adjust the solid content to 50% to obtain a vinyl polymer (A-1) solution having two free hydroxyl groups in one end region. The weight average molecular weight (Mw) was 5,800, the number average molecular weight (Mn) was 3,700, and Mw / Mn was 1.57.

[Production Example 2]
(Production of vinyl polymer: A-2)
A reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer was charged with 500 parts of methyl methacrylate, 3.2 parts of thioglycerol, and 503.2 parts of diethylene glycol diethyl ether (DEDG) and replaced with nitrogen gas. The inside of the reaction vessel was heated to 90 ° C., and 0.50 part of AIBN was added, followed by reaction for 7 hours.
Diethylene glycol diethyl ether (DEDG) was added to adjust the solid content to 50% to obtain a vinyl polymer (A-2) solution having two free hydroxyl groups in one end region. The weight average molecular weight (Mw) was 39,000, the number average molecular weight (Mn) was 19,000, and Mw / Mn was 2.17.

[Production Example 3]
(Production of vinyl polymer: A-3)
A reaction vessel was charged with 100 parts of diethylene glycol diethyl ether (DEDG) and heated to 110 ° C. while injecting nitrogen gas into the vessel. At the same temperature, 100 parts of methyl methacrylate and 2,2′-azobisisobutyronitrile ( AIBN) A polymerization reaction was performed by adding 6.0 parts of the mixture dropwise over 2 hours.
After the completion of the dropwise addition, the mixture was further reacted at 110 ° C. for 1 hour, 0.3 part of AIBN was added three times every hour, and the reaction was further continued at 110 ° C. for 1 hour to obtain an acrylic resin solution.
Diethylene glycol diethyl ether (DEDG) was added to adjust the solid content to 50% to obtain a vinyl polymer (A-3) solution. The weight average molecular weight (Mw) was 5,400, the number average molecular weight (Mn) was 2,800, and Mw / Mn was 1.93.

[Production Example 4]
(Production of polycarbonate urethane resin: A-4)
Kuraray polyol C-590 (bifunctional polycarbonate diol, manufactured by Kuraray Co., Ltd.) 100.0 parts, isophorone diisocyanate (trade name: trade name: a four-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel IPDI, manufactured by Evonik Degussa Japan Co., Ltd.) 38.7 parts, diethylene glycol diethyl ether (DEDG) 138.7 parts, dibutyltin dilaurate 0.014 parts as a catalyst, gradually heated to 100 ° C. and reacted for 2 hours It was.
This reaction solution is a colorless and transparent polycarbonate urethane resin (A-4) having a solid content of 50%, a weight average molecular weight (Mw) of 62,300, a number average molecular weight (Mn) of 28,300, and an Mw / Mn of 2 .20.

[Production Example 5]
(Production of polyester urethane resin: A-5)
Kuraray polyol P-510 (bifunctional polyester diol, manufactured by Kuraray Co., Ltd.) 100.0 parts, isophorone diisocyanate (trade name: trade name: 4 neck flask equipped with stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel (IPDI, manufactured by Evonik Degussa Japan Co., Ltd.) 38.7 parts, diethylene glycol diethyl ether (DEDG) 138.7 parts, dibutyltin dilaurate 0.014 parts as a catalyst, gradually heated to 100 ° C. and reacted for 2 hours It was.
This reaction solution is a colorless and transparent polyester urethane resin (A-5) having a solid content of 50%, a weight average molecular weight (Mw) of 62,000, a number average molecular weight (Mn) of 27,700, and an Mw / Mn of 2 .24.

[Production Example 6]
(Polyether urethane resin: production of A-6)
PP-400 (bifunctional polyether diol, manufactured by Sanyo Chemical Industries, Ltd.) 100.0 parts, isophorone diisocyanate (trade name) under a 4-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel : IPDI, manufactured by Evonik Degussa Japan Co., Ltd.) 48.3 parts, 148.3 parts of diethylene glycol diethyl ether (DEDG), 0.015 part of dibutyltin dilaurate as a catalyst, gradually heated to 100 ° C. and reacted for 2 hours went.
This reaction solution is a colorless and transparent polyether urethane resin (A-6) having a solid content of 50%, the weight average molecular weight (Mw) is 64,100, the number average molecular weight (Mn) is 29,200, and Mw / Mn is 2.24.

[Production Example 7]
(Dispersant: Synthesis method of B-1)
In a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer, 1037 parts of a 50% solid solution of vinyl polymer (A-1), 76.0 parts of isophorone diisocyanate, and 75.8 parts of diethylene glycol diethyl ether Then, 0.22 part of dibutyltin dilaurate was charged as a catalyst and replaced with nitrogen gas. The inside of the reaction vessel was heated to 100 ° C., reacted for 3 hours, cooled to 40 ° C., and dropped into a mixed solution of 35.9 parts of methyliminobispropylamine and 876.6 parts of diethylene glycol diethyl ether over 30 minutes. Then, after further reaction for 1 hour, the reaction was terminated by cooling to room temperature. The solid content was adjusted to 30% to obtain a pale yellow transparent solution of the dispersant (B-1). The amine value of the dispersant (B-1) was 48.0 mg KOH / g.

(Molecular weight measurement of commercial binder resin)
Table 1 shows the binder resins used in Examples and Comparative Examples, which are obtained by measuring the weight average molecular weight (Mw) and number average molecular weight (Mn) of commercially available binder resins and calculating Mw / Mn. To do.

First, Pigment Dispersion A was prepared with the following composition. This dispersion was prepared by adding a pigment and a dispersant into an organic solvent, stirring until uniform with a high speed mixer or the like, and dispersing the obtained mill base with a horizontal sand mill for about 1 hour.
LIONOL BLUE FG-7400G (phthalocyanine pigment manufactured by Toyo Ink Manufacturing Co., Ltd.) 35.00 parts Azisper PB821 (pigment dispersant manufactured by Ajinomoto Fine Techno Co.) 12.50 parts ethylene glycol monobutyl ether acetate 52.50 parts

Further, a pigment dispersion B was prepared in the same manner as in Production Example 1 with the following composition.
・ Fastogen Super Magenta RG (quinacridone pigment manufactured by DIC) 32.0 parts ・ Azisper PB821 (pigment dispersant manufactured by Ajinomoto Fine Techno Co.) 12.8 parts ・ Diethylene glycol diethyl ether 55.2 parts

Further, a pigment dispersion C was prepared in the same manner as in Production Example 1 with the following formulation.
・ YELLOW PIGMENT E4GN (Nickel complex azo pigment made by LANXESS) 30.00 parts ・ Solspers 24000GR (pigment dispersant made by Lubrizol) 16.50 parts ・ Diethylene glycol ethyl methyl ether 53.50 parts

Further, a pigment dispersion D was prepared in the same manner as in Production Example 1 with the following formulation.
ELFTEX 415 (Carbot Black Carbon Black) 35.00 parts Dispersant: B-1 (30% solid DEDG varnish) 46.67 parts Diethylene glycol diethyl ether 18.33 parts

  Inks of Examples 1 to 14 and Comparative Examples 1 to 12 were prepared with the formulations shown in Table 2.

Abbreviations in Table 2 NMP: N-methyl-2-pyrrolidone GBL: gamma-butyrolactone ε-CL: epsilon caprolactone MOZ: 3-methyl-2-oxazolidinone EOZ: 3-ethyl-2-oxazolidinone DMSO: dimethyl sulfoxide BGAc: ethylene glycol Monobutyl ether acetate DEDG: Diethylene glycol diethyl ether MEDG: Diethylene glycol methyl ethyl ether DMTeG: Tetraethylene glycol dimethyl ether

As is apparent from Table 3 below, the ink compositions of Examples 1 to 14 using only those specified in the present invention for the selection of the binder resin in the ink are all in print stability, printed matter performance, and drying property. Excellent. On the other hand, Comparative Examples 1, 6, and 12 use only one or two types having a small weight average molecular weight (Mw), so that the printing stability is good, but the printed matter performance and drying properties are good. Was inferior. Although Comparative Examples 5, 8, 9, 10, and 11 use a resin having a weight average molecular weight (Mw) that is too large or Mn / Mw of 3 or more, the printed material performance and drying properties are good. As a result, the printing stability was inferior. Comparative Examples 2, 3, 4, and 7 have a large weight average molecular weight (Mw) such as vinyl polymer A-2 having a weight average molecular weight (Mw) of 39000 and resin 3 (VYHD) having a weight average molecular weight (Mw) of 48000. Since the binder resin was used alone, the printing stability at low temperature and low humidity was lost, resulting in poor printing stability.
The evaluation method is shown below.

<Printing stability>
About the ink compositions obtained in Examples 1 to 14 and Comparative Examples 1 to 12, in a 25 ° C. environment, the surface was free with a solvent ink inkjet printer Color Painter 64S Plus manufactured by Seiko I Infotech Co., Ltd. The treatment was continuously printed on the treated polyvinyl chloride resin sheet for 50 hours, and the occurrence frequency of dot omission, flight bending or ink scattering was evaluated. At this time, the environmental temperature and humidity at the time of printing are controlled, and the experiment is performed in two environments of medium temperature and medium humidity = temperature: 23 degrees, humidity: 60 to 70%, low temperature and low humidity = temperature: 15 ° C. or less, humidity: 40% or less. went. In the table, a nozzle check pattern was printed after 50 hours of continuous printing, and the number of missing dots, flying bends, or ink splatters was confirmed, and the number was listed.

<Alcohol resistance>
About the ink composition obtained in Examples 1-14 and Comparative Examples 1-12, the surface is a non-processed polyvinyl chloride resin sheet in Solvent ink inkjet printer Color Painter 64S Plus by Seiko Eye Infotech Co., Ltd. The printed surface was evaluated for alcohol resistance using a rubbing tester (model AB301, manufactured by Tester Sangyo). As evaluation conditions, a test cloth (gold width 3) diluted with ethanol / water = 70/30 was dropped and applied at a load of 200 g, 50 reciprocations, and the coated surface was not peeled off at all. No. 5, coloring was observed on the test cloth, but no noticeable change was observed on the printed surface, no coloring was observed on the printed surface, and no slight color fading was observed on the printed surface. The case where the substrate was seen after being peeled off was evaluated as 2, and the case where the ink was peeled off and the substrate was seen more than half was evaluated as 1.

<Gasoline resistance>
About the ink composition obtained in Examples 1-14 and Comparative Examples 1-12, the surface is a non-processed polyvinyl chloride resin sheet in Solvent ink inkjet printer Color Painter 64S Plus by Seiko Eye Infotech Co., Ltd. The printed surface was evaluated for gazolin resistance using a rubbing tester (Model AB301, manufactured by Tester Sangyo). As evaluation conditions, 1 drop of gazoline was applied to a test cloth piece (gold width 3), the load was 200 g, and 10 reciprocations were carried out. Although it was seen, the printed surface showed no noticeable change 4, the test piece was colored, and the printed surface was slightly discolored 3, but it was peeled off but the substrate was visible 2 was evaluated as 1 and the ink was peeled off and the substrate could be seen more than half.

<Glossy>
About the ink composition obtained in Examples 1-14 and Comparative Examples 1-12, the surface is a non-processed polyvinyl chloride resin sheet in Solvent ink inkjet printer Color Painter 64S Plus by Seiko Eye Infotech Co., Ltd. The gloss was evaluated with a 60 ° gloss meter.

<Drying>
About the ink compositions obtained in Examples 1 to 14 and Comparative Examples 1 to 12, in a 25 ° C. environment, the surface was free with a solvent ink inkjet printer Color Painter 64S Plus manufactured by Seiko I Infotech Co., Ltd. Solid printing with a printing rate of 100, 200, and 300% was performed on the treated polyvinyl chloride resin sheet by three-color printing of Cyan, Magenta, and Yellow, and the time until drying at 40 ° C. was measured. Specifically, a tentacle test was performed every 10 seconds, and the time during which ink did not adhere to the hand was measured.

Claims (7)

It contains at least a pigment, an organic solvent, and two or more types of binder resins having different weight average molecular weights (Mw). Among the two or more types of binder resins used, the binder resin having the smallest weight average molecular weight (Mw) is Mwα. An ink composition characterized by satisfying the general formulas (1) and (2) when a binder resin having a large average molecular weight (Mw) is Mwβx (x = 1, 2, 3...).

General formula (1): Mwβx (x = 1, 2, 3...) −Mwα ≧ 10,000
General formula (2): 1,000 <Mwα <30,000 and 20,000 <Mwβx <100,000 The ink composition according to claim 1, wherein the relationship between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the two or more binder resins contained is in the following range.
1 <Mw / Mn <3
The ink composition according to claim 1 or 2, wherein the two or more kinds of binder resins are vinyl chloride resin and / or acrylic resin. The ink composition according to any one of claims 1 to 3, further comprising any one or more of the solvents represented by formulas (a) to (d) as an organic solvent.
R ₁ CO (OR ₂ ) _Z OR ₃ (a) R ₄ CO (OR ₅ ) _Z OCOR ₆ (b)
R ₇ (OR ₈ ) _Z OR ₉ (c) R ₁₀ COOR ₁₁ (d)
(In the formula, R ₂ , R ₅ , R ₈ are each independently an ethylene group or a propylene group, R ₁ , R ₃ , R ₄ , R ₆ are each independently an alkyl group having 1 to 4 carbon atoms, R _7. , R ₉ is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ₁₀ is a 2-hydroxyethyl group, R ₁₁ is an alkyl group having 1 to 8 carbon atoms, and Z is an integer of 1 to 3. .) The ink composition according to any one of claims 1 to 4, further comprising a nitrogen-containing, sulfur-containing, or lactone solvent as part of the organic solvent. The ink composition according to any one of claims 1 to 5, further comprising a dispersant in the ink composition. An inkjet ink using the ink composition according to any one of claims 1 to 6.