JP2010111741A - Water-based ink composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based inkjet ink composition capable of being directly printed not only on an absorptive base material such as paper but also on a non-absorptive material, achieving resistance of a printed product superior to that of a printed product printed with a solvent ink, and obtained by using a pigment. <P>SOLUTION: The water-based ink composition contains at least the pigment, water, an organic solvent and a vinyl chloride-based resin emulsion used as a binder resin. The vinyl chloride-based resin emulsion is preferably an emulsion of a vinyl chloride-vinyl acetate copolymer or a vinyl chloride-acrylic copolymer in the water-based ink composition. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a water-based ink composition having excellent water resistance, weather resistance, and friction resistance.

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, in which images and characters are printed using minute ink droplets ejected from the nozzles of an inkjet head, printers that can handle A-0 size have been developed in recent years. Due to the increasing use environment, ink jet printing inks having excellent water resistance, weather resistance, and friction resistance have been actively developed.

  In particular, in inkjet printing inks used for the sign industry, pigment-based solvent inkjet inks that use organic solvents as solvents instead of water-based inkjet inks in which colorants such as water-soluble dyes are added to general water. Mainly used. This requires the ability to print directly on the surface of a non-absorbent substrate such as a polyvinyl chloride sheet, which is used as a medium for outdoor advertising and the like. It is considered that a pigment ink composition containing a binder resin that adheres firmly to the surface of the absorbent substrate and an organic solvent that can dissolve the binder resin or the surface of the non-absorbable substrate is considered suitable. It is.

However, the long-term use of a solvent is not preferable because there are environmental problems such as VOC and harmful problems such as acute toxicity, mutagenicity, carcinogenicity, and reproductive toxicity. Therefore, at present, the development of water-based inkjet ink using a pigment as a colorant is underway (Patent Document 1).
However, although the developed water-based inkjet ink can be printed directly on an absorbent substrate such as paper, it cannot be printed directly on the surface of a non-absorbent substrate and has poor printed matter resistance. The current situation is not (Patent Document 2).
JP-A-11-183920 Japanese Patent No. 4148424

  The present invention has been made in view of the above-described problems, and the object of the present invention is to directly print not only on an absorbent substrate such as paper but also on a non-absorbent substrate, and is printed with a solvent ink. Another object of the present invention is to provide a water-based ink composition using a pigment, particularly an ink-jet ink composition, which can realize printed matter resistance superior to that of a printed product.

The above object of the present invention is achieved by the following configurations.
The present invention provides a water-based ink composition characterized by using at least a pigment, water, an organic solvent, and a vinyl chloride resin emulsion as a binder resin.
The water-based ink composition is characterized in that the vinyl chloride resin emulsion is an emulsion of vinyl chloride-vinyl acetate copolymer or vinyl chloride-acrylic copolymer.
Furthermore, the average particle diameter of the particle | grains in a vinyl chloride-type resin emulsion is 30-500 nm, The water-based ink composition characterized by the above-mentioned.
Further, the organic solvent is a water-soluble organic solvent having a boiling point equal to or higher than that of water.
Further, the water-soluble organic solvent having a boiling point higher than that of water includes at least one of an alcohol solvent, a solvent represented by the general formula (1), a nitrogen-containing, sulfur-containing or lactone solvent. The water-based ink composition according to claim 1, wherein:

R ₁ (OR ₂ ) _Z OR ₃ (1)
(In the formula, R ₂ represents an ethylene group or a propylene group, R ₁ and R ₃ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and Z represents an integer of 1 to 6).
Furthermore, it is related with the water-based ink composition which is an inkjet ink.
Furthermore, it is related with the water-based ink composition which is the inkjet ink for non-absorbing base-material printing.

According to the present invention, by using a vinyl chloride resin emulsion having good adhesion to a non-absorbing substrate as a binder resin, not only an absorptive substrate such as paper but also a non-absorbing substrate. There is provided an aqueous ink composition, particularly an inkjet ink composition, using a pigment that can be directly printed and can realize printed matter resistance superior to a printed matter printed with a solvent ink.

Hereinafter, the best mode for carrying out the present invention will be described.

  The ink composition of the present invention includes at least a pigment excellent in weather resistance, a water-insoluble resin emulsion that firmly adheres the pigment to the surface of the non-absorbent printing medium, a water-soluble organic solvent having a boiling point of water or higher, An aqueous pigment ink composition containing water.

  As the water-insoluble resin emulsion excellent in adhesion to the non-absorbable printing medium surface, a vinyl chloride resin emulsion is preferable, and a vinyl chloride resin emulsion obtained by an emulsion polymerization method is most preferable. By using an emulsification dispersion method, it is possible to emulsify a high molecular weight, low acid value vinyl chloride resin with a high solid content, and vinyl chloride obtained by a phase inversion emulsification method or an emulsification dispersion method. This is because the adhesion and resistance of the ink coating to the surface of the non-absorbable printing medium, which cannot be satisfied by the ink using the resin emulsion, can be realized. Specific examples include Vinibrand 271, Vinibrand 278, Vinibrand 603, Vinibrand 690, Vinibrand 900, Vinibrand 902, Vinibrand 985, and UCAR AW-875, manufactured by Dow Chemical. The resin is preferably contained in the ink in an amount of 0.1 to 40% by weight, particularly preferably 3.0 to 30% by weight. If 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. If the addition amount is 40% by weight or more, the ink viscosity is too high. Since it falls, it is not preferable.

In addition, the vinyl chloride resin is preferably vinyl chloride-vinyl acetate or vinyl chloride-acrylic copolymer from the viewpoint of easiness of film formation in the drying step and gloss of the ink coating film. The higher the molecular weight of the vinyl chloride resin, the better the ink coating film resistance and the coating film stretchability.
The average particle size of the particles in the vinyl chloride resin emulsion is preferably 30 to 500 nm, and most preferably 50 to 400 nm. An average particle size of 500 nm or more is not preferable because the viscosity of the emulsion itself increases and the discharge performance from the inkjet head deteriorates.
The acid value of the vinyl chloride resin is preferably 1 to 100 mgKOH / g, more preferably 1 to 50 mgKOH / g, and most preferably 1 to 10 mgKOH / g. If the acid value is less than 1 mg KOH / g, it cannot be emulsified and is unstable over time, and if it is 100 mg KOH / g or more, the rub resistance, water resistance, and chemical resistance of the ink coating film are deteriorated.

The organic solvent used in the present invention is preferably a water-soluble organic solvent having a boiling point higher than that of water. When the boiling point is lower than that of water, when used as an ink-jet ink, drying on the ink-jet head nozzle is accelerated, which causes clogging.
Examples of such organic solvents include alcohol solvents such as butyl alcohol, 1,3-propanediol, and glycerin, or 3-methyloxazolidinone, 3-ethyloxazolidinone, 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1- Nitrogen-containing or sulfur-containing or lactone solvents such as ethyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, ε-caprolactone, ε-caprolactam, δ-valerolactone, δ-valerolactam, dimethyl sulfoxide, etc. It is preferable to include any one or more of the solvent represented by the formula (1).

R ₁ (OR ₂ ) _Z OR ₃ (1)
(In the formula, R ₂ represents an ethylene group or a propylene group, R ₁ and R ₃ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and Z represents an integer of 1 to 6).

Examples of the organic solvent corresponding to the general formula (1) 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, and diethylene glycol mono Ethyl 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 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.
Among these, it is particularly preferable to include any one or more of 3-methyloxazolidinone, 1-methyl-2-pyrrolidone, γ-butyrolactone, ε-caprolactone, tetraethylene glycol dimethyl ether, and triethylene glycol monobutyl ether.

  The addition amount is most preferably 5 to 50%. If the content is less than 5%, the ink is dried on the ink jet head nozzle and ink cannot be ejected. This is not preferable because it causes problems.

  Examples of the printing medium of the present invention include not only absorbent printing media such as paper, but also non-absorbing printing media such as polyvinyl chloride resin sheets, polyolefin-based sheets, glass, and metals. Particularly preferred are polyvinyl chloride resins. It is a sheet.

  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.

  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, a hydrolysis inhibitor, an activator, and a dispersant.

  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 water or a water-organic solvent mixed solvent using a paint shaker, a sand mill, a roll mill, a medialess disperser, or the like. It is manufactured by diluting with the water, organic solvent and vinyl chloride resin emulsion 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, “parts” and “%” represent “parts by weight” and “% by weight”. In addition, the numerical values of the resin acid value, molecular weight, and minimum film-forming temperature (MFT) are catalog values measured by Dow Chemical Company, Johnson Polymer Company, and Nissin Chemical Company. The average particle size was diluted 200 times with ion-exchanged water and measured with a Microtrac UPA150 (a wet particle size distribution meter manufactured by Nikkiso Co., Ltd.).

[Production Example 1]
(Production of aqueous dispersion 1)
Crude copper phthalocyanine (copper phthalocyanine manufactured by Toyo Ink Manufacturing Co., Ltd.): 250 parts, sodium chloride: 2500 parts, and polyethylene glycol 300 (manufactured by Tokyo Chemical Industry Co., Ltd.): 160 parts were charged into a 1 gallon kneader (manufactured by Inoue Seisakusho Co., Ltd.) made of styrene. Kneaded for 4 hours. Next, this mixture was poured into 2.5 liters of warm water and stirred for about 1 hour with a high speed mixer while being heated to about 80 ° C. to form a slurry, followed by repeated filtration and washing 5 times to obtain sodium chloride and An aqueous pigment dispersion (treated pigment dispersion) having a solid content of 50% was obtained by removing the solvent.
Aqueous pigment dispersion (treated pigment dispersion, solid content 50% product): 30.0 parts, acrylic resin aqueous solution (Johnson Polymer 62 “John Crill 62” solid content 34.6%): 3.0 parts, dispersion Agent ("Emulgen 420" manufactured by Kao Co., Ltd .: 2.0 parts, purified water: 50.0 parts, 6.0 parts of glycerin are placed in a sand mill and dispersed for 4 hours. Thus, an aqueous pigment dispersion 1 was obtained.

[Production Example 2]
(Production of aqueous dispersion 2)
In place of the crude copper phthalocyanine of Production Example 1, 260 parts of a yellow pigment (“Poster Palm Yellow H3G” manufactured by Hoechst) was used to prepare an aqueous pigment dispersion 2 in the same procedure as in Production Example 1.

[Production Example 3]
(Production of aqueous dispersion 3)
Red pigment (“Poster Palm Pink E” manufactured by Hoechst): 250 parts, sodium chloride: 2500 parts, and polyethylene glycol 300 (manufactured by Tokyo Chemical Industry Co., Ltd.): 160 parts are charged into a 1 gallon kneader (manufactured by Inoue Seisakusho) made of styrene. Kneaded for 3 hours. Next, this mixture was poured into 2.5 liters of warm water and stirred for about 1 hour with a high speed mixer while being heated to about 80 ° C. to form a slurry, followed by repeated filtration and washing 5 times to obtain sodium chloride and An aqueous pigment dispersion (treated pigment dispersion) having a solid content of 50% was obtained by removing the solvent.
Aqueous pigment dispersion (treated pigment dispersion, solid content 50% product): 30.0 parts, acrylic resin aqueous solution (Johnson Polymer 62 “John Crill 62” solid content 34.6%): 3.0 parts, dispersion Agent ("Emulgen 420" manufactured by Kao Co., Ltd .: 2.0 parts, purified water: 50.0 parts, 6.0 parts of glycerin are placed in a paint shaker and dispersed for 4 hours, and then filtered through membrane filters of 1 μm and 0.45 μm. Thus, an aqueous pigment dispersion 3 was obtained.

  Table 1 shows the aqueous emulsions evaluated this time.

[Example 1]
(Production of water-based inkjet ink 1)
Aqueous dispersion 1: 32.3 parts, resin 1: 44.4 parts, 1-methyl-2-pyrrolidone: 10.0 parts, New Coal 291GL (surfactant manufactured by Nippon Emulsifier Co., Ltd.): 2.0 parts, Proxel GXL (Abyssia Preservative): 0.2 parts, ion-exchanged water: 11.1 parts are stirred and mixed with a high-speed mixer, and then filtered with 1 μm and 0.45 μm membrane filters. 1 was obtained.

[Examples 2-8, Comparative Examples 1-2]
A water-based inkjet ink was prepared in the same procedure as in Example 1, using the raw materials described in Table 2 as components.
Both Johncrill 840 and 74J are acrylic resin emulsions.

As is clear from Table 3, the ink compositions of Examples 1 to 8 using only the binder resin specified in the present invention in the ink are non-absorbing like a polyvinyl chloride resin sheet having an untreated surface. In addition to being able to print directly on a conductive substrate, the printed materials are resistant to ethanol, water, and abrasion. In particular, Example 3 using an emulsion of vinyl chloride-vinyl acetate copolymer and Example 4 using an emulsion of vinyl chloride-acrylic copolymer are not only resistant to printed matter, but also have high ink film gloss. Is particularly good.
On the other hand, Comparative Examples 1 and 2 use an emulsion obtained by emulsifying and dispersing an acrylic resin, and since the acid value of the resin is high and the resin main component is acrylic, a polyvinyl chloride resin is used. Direct printing on the sheet was not possible, and the printed matter resistance was poor.
The evaluation method is shown below.

<Method for confirming whether or not direct printing is possible on a surface-untreated polyvinyl chloride resin sheet>
For the ink compositions obtained in Examples 1 to 8 and Comparative Examples 1 and 2, using Hi-Fi JET PRO II Model FJ-540 (manufactured by Roland DG), the surface was treated as an untreated polyvinyl chloride resin sheet. Solid printing was performed every 10% at a printing rate of 50 to 100%, and it was confirmed whether or not a printed matter having no unevenness was obtained at all the printing rates without repelling on the substrate.

<Alcohol resistance>
For the ink compositions obtained in Examples 1 to 8 and Comparative Examples 1 and 2, using Hi-Fi JET PRO II Model FJ-540 (manufactured by Roland DG), the surface was treated as an untreated polyvinyl chloride resin sheet. Solid printing was performed at a printing rate of 100%, and the printed surface was evaluated for alcohol resistance with 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.

<Water resistance>
For the ink compositions obtained in Examples 1 to 8 and Comparative Examples 1 and 2, using Hi-Fi JET PRO II Model FJ-540 (manufactured by Roland DG), the surface was treated as an untreated polyvinyl chloride resin sheet. Solid printing was performed at a printing rate of 100%, and the printing surface was evaluated for water resistance with a rubbing tester (Model AB301, manufactured by Tester Sangyo). As evaluation conditions, 1 drop of water was applied to a test cloth (gold width 3), the load was 200 g, 10 reciprocations were carried out, the coated surface was not peeled off at all, and the test cloth was colored. 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.

<Abrasion resistance>
For the ink compositions obtained in Examples 1 to 8 and Comparative Examples 1 and 2, using Hi-Fi JET PRO II Model FJ-540 (manufactured by Roland DG), the surface was treated as an untreated polyvinyl chloride resin sheet. Solid printing was performed at a printing rate of 100%, and the printed surface was evaluated for rubbing resistance with a rubbing tester (Model AB301, manufactured by Tester Sangyo). Evaluation conditions were as follows: test cloth piece (gold width 3), load 200g, 50 reciprocations, the coated surface was not peeled off at all, and the test cloth piece was colored. 4 shows no noticeable change, 3 is colored on the test piece and 3 is slightly discolored on the printed surface, 2 is peeled but the substrate is visible, 2 is ink. A value of 1 was taken when the substrate was seen more than half.

<Glossy>
For the ink compositions obtained in Examples 1 to 8 and Comparative Examples 1 and 2, using Hi-Fi JET PRO II Model FJ-540 (manufactured by Roland DG), the surface was treated as an untreated polyvinyl chloride resin sheet. Solid printing with a printing rate of 100% was performed, and the glossiness was measured with a 60 ° gloss meter.

Claims (7)

A water-based ink composition comprising at least a pigment, water, an organic solvent, and a vinyl chloride resin emulsion as a binder resin. 2. The aqueous ink composition according to claim 1, wherein the vinyl chloride resin emulsion is an emulsion of vinyl chloride-vinyl acetate copolymer or vinyl chloride-acrylic copolymer. Furthermore, the average particle diameter of the particle | grains in a vinyl chloride resin emulsion is 30-500 nm, The water-based ink composition of Claim 1 or 2 characterized by the above-mentioned. The water-based ink composition according to any one of claims 1 to 3, further comprising a water-soluble organic solvent having a boiling point equal to or higher than water as the organic solvent. Furthermore, the water-soluble organic solvent having a boiling point higher than that of water includes at least one of an alcohol solvent, a solvent represented by the general formula (1), a nitrogen-containing, sulfur-containing or lactone solvent. The water-based ink composition according to claim 1, wherein the water-based ink composition is a water-based ink composition.
R ₁ (OR ₂ ) _Z OR ₃ (1) (wherein R ₂ is an ethylene group or a propylene group, R ₁ and R ₃ are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, _Z represents an integer of 1 to 6.) The aqueous inkjet ink according to any one of claims 1 to 5. The water-based inkjet ink for non-absorbent substrate printing according to any one of claims 1 to 6.