JP2010018730A - Solvent-based inkjet ink composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waterless solvent-based inkjet ink composition capable of utilizing various pigments and resins, and having good printability for a non-absorbing material provided with no ink receiving layer or dryability after printing, and excellent fastness of prints without corroding parts in the interior of piezo type inkjet printers. <P>SOLUTION: The amount of organic solvents is ≥90 wt.% in an ink. The organic solvents are alcoholic solvents, and comprise a medium-boiling alcoholic solvent having ≥90 to ≤140°C boiling point at 1 atm. ; a low-boiling alcoholic solvent having <90°C boiling point at 1 atm. ; and/or a high-boiling alcoholic solvent having >140°C boiling point at 1 atm. In the organic solvents, the amount of the medium-boiling alcoholic solvent is ≥40 wt.%; the amount of the low-boiling alcoholic solvent is ≤60 wt.%; and the amount of the high-boiling alcoholic solvent is ≤25 wt.%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solvent-based ink-jet ink composition that does not contain water and is used in a piezo-type ink-jet printer for a non-absorbing material that is not provided with an ink-receiving layer.

  In recent years, full-color printing can be easily performed in various applications by inkjet printing. The ink jet printing technique is a printing technique in which an image is formed by ejecting ink from a head nozzle as fine ink droplets according to an electric input signal. Features of this technology include high resolution and low noise, and ink jet printers are used as office and personal computer terminals. Furthermore, since an image can be formed in accordance with an electric input signal, it is excellent in small-volume and multi-variable variable printing, and is also used in industrial applications such as large signs.

  Typical inkjet methods include a piezo method and a thermal method. The thermal method is a method in which heat is instantaneously applied to ink and ink is ejected from the head nozzle, and the piezo method is a method in which ink is ejected from the head nozzle by pressure using a piezoelectric element. Because of this difference, the piezoelectric type has fewer restrictions on the raw materials that can be used for the ink than the thermal type, and various raw materials can be used. Because of this advantage, the piezo method is an inkjet method that can be easily developed for various applications.

  In industrial applications such as large signboards, durable materials are used for the base material of signboards, but such materials are often non-absorbable materials. When printing on a plastic which is a non-absorbing material, in consideration of printability and drying after printing, it is general to provide an ink receiving layer on the plastic and print on the ink receiving layer. If an ink-receptive layer is not provided when water-based ink is used as inkjet ink, ink absorption and drying properties of non-absorbent materials are insufficient, ink bleeding is likely to occur, and good print quality is ensured. Difficult to do. For example, as disclosed in Japanese Patent No. 3830092 and Japanese Patent No. 4127531, an ink receiving layer provided on a plastic which is a non-absorbing material for water-based ink has been developed.

  If the base material of the non-absorbent material is a film, the ink receiving layer can be easily formed with a general coater, and there is no problem with water-based ink, but the shape of the base material changes depending on the purpose of industrial use. If it is not a film but a plate or the like, it is difficult to form an ink receiving layer for water-based ink. In view of this, developments have been made to ensure good print quality even with non-absorbing materials not provided with an ink receiving layer by improving ink.

  As an inkjet ink for printing on a non-absorbing material not provided with an ink receiving layer, for example, in Japanese Patent No. 4082681 and Japanese Patent Application Laid-Open No. 2005-126540, an ultraviolet ray containing a pigment, an ultraviolet curable resin, and a photopolymerization initiator A curable inkjet ink composition has been developed. However, the ultraviolet curable type requires a facility for irradiating ultraviolet rays with a mercury lamp after printing, and is not versatile.

  On the other hand, in Japanese Patent Application Laid-Open No. 10-245513, a solvent-based inkjet ink containing a colorant, a solvent, and a styrene / maleic acid resin has been developed. In this publication, as a preferable solvent, in addition to the solubility and dispersibility of the colorant and the solubility of the styrene / maleic acid resin, while the drying property on the non-absorbing surface is good, In the discharge process, it is desirable to have a slow drying property. As a solvent that exhibits such contradictory drying properties and slow drying properties in this kind of ink composition system containing this styrene-maleic acid resin, alcohol is used. And ethers are described as being optimal. Thus, it is a fixed solvent in a fixed resin and is not suitable for using various resins.

  As a similar solvent-based inkjet ink, for example, JP-A No. 2002-146245 discloses an ink composition for an inkjet printer containing a colorant, a film-forming resin, and a lower alcohol having 4 or less carbon atoms. In this publication, the coloring agent is optimized for a continuous (charge control) method that is limited to a specific carbon black and is neither a piezo-type nor a thermal type. It was developed. It is not assumed that full-color printing is performed as in the piezo type, and various colorants cannot be used.

As a solvent-based inkjet ink that can use various colorants (pigments) and various resins, for example, in Japanese Patent No. 3701957 and Japanese Patent No. 3998783, a base material that is a non-absorbent material is slightly melted. Those using various solvents have been developed. However, in the case of these solvents, it is possible to obtain good print quality in the case of polyvinyl chloride plastic as a non-absorbing material, but in the case of non-absorbing materials such as plastics and metals and glass with extremely low solubility. If the ink receiving layer is not provided, the boiling point of the solvent is relatively high, so that the drying property of the ink is poor, and there is a problem of bleeding and an ink transfer problem that the ink moves when the printed matter is superimposed. In addition, printing fastness may be insufficient. Further, depending on the type of the solvent, there is a problem that parts inside the printer are eroded so that the solvent may melt the base material that is a non-absorbing material.
Japanese Patent No. 3830092 Japanese Patent No. 4127531 Japanese Patent No. 4082681 JP 2005-126540 A Japanese Patent Laid-Open No. 10-245513 JP 2002-146245 A Japanese Patent No. 3701957 Japanese Patent No. 3988883

  The problem to be solved by the present invention is that various pigments and resins can be used, the parts inside the piezo ink jet printer are not eroded, and the ink receiving layer is not provided. It is an object of the present invention to provide a water-based solvent-based inkjet ink composition that has good printability to a non-absorbent material, good drying properties after printing, and excellent printing fastness.

  Since the piezo method is a method of ejecting ink from the head nozzle by pressure using a piezoelectric element, the raw material that can be used for ink is more than the thermal method that instantaneously applies heat to the ink and ejects ink from the head nozzle. There are few restrictions and various pigments and resins can be used. Therefore, it has the advantage that full-color printing can be performed in various applications. However, if a special solvent is used or a solvent that easily erodes parts is used, this advantage is lost. The present inventors have conducted research on inks that can use various pigments and resins while being a solvent that does not easily erode components.

  Many piezo inkjet printers are compatible with water-based inks, but they do not easily erode parts of the printer, and do not contain water using alcohol-based solvents that are close to the properties of water as organic solvents that support piezo-type. It has been found that when the proportion of the organic solvent in the ink is 90% by weight or more, it works well. In addition, in order to obtain various performances required in use conditions, it has been found that even if an alcohol solvent having a higher boiling point or an alcohol solvent having a lower boiling point than the boiling point of water is mixed, it will work well.

  In the present invention, for convenience, an alcohol solvent near the boiling point of water is called a medium boiling alcohol solvent, a solvent having a lower boiling point is called a low boiling alcohol solvent, and a solvent having a higher boiling point is called a high boiling alcohol solvent. It is out. If specifically defined by the boiling point value, an alcohol solvent lower than 90 ° C. is a low boiling alcohol solvent at a boiling point of 1 atm, and an alcohol solvent of 90 ° C. or higher and 140 ° C. or lower is a medium boiling alcohol solvent. An alcohol solvent having a temperature higher than 140 ° C. is a high boiling alcohol solvent.

  Here, when the number of low-boiling alcohol solvents or high-boiling alcohol solvents increases, the following problems may occur. In the case of the low-boiling alcohol solvent, drying of the head nozzle of the printer is promoted, the head nozzle is clogged, and stable ink ejection may not be obtained. In the case of a high-boiling alcohol solvent, drying of the ink is slow, a problem of bleeding occurs, and print quality may be deteriorated. However, in the organic solvent, the ratio of the medium boiling alcohol solvent is 40% by weight or more, the ratio of the low boiling alcohol solvent is 60% by weight or less, and the ratio of the high boiling alcohol solvent is 25% by weight or less. The present inventors have found that they can be used without causing such problems.

  In addition, good print quality cannot be obtained unless the pigment is dispersed in the ink. However, in the present invention, the pigment is dispersed in the ink through a manufacturing process of pigment dispersion using an organic solvent and resin mixing. It has been able to be in a state that has been.

  The present invention relates to a solvent-based inkjet ink composition for a non-absorbent material used in a piezo-type inkjet printer, comprising at least a pigment, a resin, and an organic solvent, and the proportion of the organic solvent in the ink is 90% by weight. The organic solvent is an alcohol solvent, a medium boiling alcohol solvent having a boiling point of 90 ° C. or more and 140 ° C. or less at 1 atmosphere, a low boiling alcohol solvent having a boiling point of less than 90 ° C. at 1 atmosphere, and And / or a high-boiling alcohol solvent having a boiling point of greater than 140 ° C. at 1 atm. In the organic solvent, the proportion of the medium-boiling alcohol solvent is 40% by weight or more, and the proportion of the low-boiling alcohol solvent Is 60% by weight or less, and the proportion of the high boiling alcohol solvent is 25% by weight or less. Further, the ink is characterized in that it is for full-color printing by a combination of at least three colors consisting of yellow, magenta and cyan, or a combination of at least four colors obtained by adding black to these.

  According to the present invention, various pigments and resins can be used, the parts inside the piezo-type ink jet printer are not eroded, and the non-absorbing material such as plastic, metal and glass without the ink receiving layer is provided. It has become possible to provide a water-based solvent-based inkjet ink composition that has good printability, good drying properties after printing, and excellent printing fastness. In addition, the pigment can be dispersed in the ink through a manufacturing process of pigment dispersion with an organic solvent and resin mixing.

  The medium-boiling alcohol solvent may be used alone or in combination, as long as the ratio is 40% by weight or more in the organic solvent. In addition, in order to obtain various performances required in use conditions, it is better to use a mixture with a low-boiling alcohol solvent or a high-boiling alcohol solvent. However, water is not used for the organic solvent using these alcohol solvents. This is because even if it is a water-soluble alcohol-based solvent, if it contains water, the print quality will not be good in the present invention.

  In the ink, the content of these organic solvents can be changed depending on the type of pigment or resin used or additives, but it is preferably 90% by weight or more for use in a piezo ink jet printer. 93% by weight or more is more preferable. The reason why the content of the organic solvent is large is to stabilize ink ejection from the head nozzle in the piezo method. However, these weight% values are only based on measurement, and are values that do not take into account the decrease due to natural evaporation.

  Examples of medium boiling alcohol solvents include 1-propanol, 1-butanol, 2-butanol, 3-pentanol, 2-methyl-1-butanol, 2-methyl-2-butanol, isoamyl alcohol, 3-methyl- Examples include 2-butanol, 4-methyl-2-pentanol, allyl alcohol, propylene glycol monomethyl ether, and propylene glycol monoethyl ether.

  Examples of the low boiling alcohol solvent include methanol, ethanol, isopropanol and the like, and examples of the high boiling alcohol solvent include 1-hexanol, 1-heptanol, 2-heptanol and 3-heptanol.

  The pigment is not particularly limited, and conventionally known pigments can be used. Lake pigments, organic pigments such as insoluble pigments, and inorganic pigments such as carbon black can be used. Examples thereof include azo pigments, azomethine pigments, phthalocyanine pigments, quinacridone pigments, anthraquinone pigments, diketopyrrolopyrrole pigments, methine pigments, azomethine azo pigments, perylene pigments, perinone pigments, and isoindolinone pigments.

  Examples of pigments used as yellow are C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 75, C.I. I. Pigment yellow 83, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 95, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 98, C.I. I. Pigment yellow 109, C.I. I. Pigment yellow 110, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 147, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. And CI Pigment Yellow 185.

  Examples of pigments used as magenta are C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 112, C.I. I. Pigment red 122, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 168, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. Pigment red 184, C.I. I. Pigment red 202, C.I. I. Pigment red 254 and the like.

  Examples of pigments used as cyan are C.I. I. Pigment blue 15: 1, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 22, C.I. I. And CI Pigment Blue 60.

  If the ink is a combination of at least three colors of yellow, magenta, and cyan, full color printing is possible. Although it is possible to develop a color from these three colors as black, depending on the type of non-absorbent material, it is difficult to develop a mixed color, so full color printing is possible even with a combination of at least four colors with black added to them. It becomes. Examples of pigments used as black are C.I. I. Pigment black 1, C.I. I. Pigment black 6, C.I. I. Pigment black 7 and the like.

  In addition to these color combinations, light color inks may be combined for high-definition images. Light color inks include light magenta and light cyan. In this case, the above pigment is diluted to 1/6 to 1/2. For example, when manufacturing light magenta, it may be used by diluting it to a ratio of 1/2 of the normal ratio of magenta.

  Other special colors may be used. For example, examples of pigments used as green include C.I. I. Pigment green 7, C.I. I. Examples of pigments used by CI Pigment Green 37 as violet, for example, I. Pigment violet 19, C.I. I. Pigment violet 23, C.I. I. And CI Pigment Violet 37.

  In order to make these pigments dispersed in the ink, the pigment, resin and organic solvent are not mixed and dispersed together, but the pigment dispersion is first prepared by dispersing the pigment in the organic solvent. The manufacturing process and the subsequent process of mixing the pigment dispersion and the resin are performed.

  The step of preparing the pigment dispersion is performed by dispersing the pigment in an organic solvent using a disperser such as a sand mill or a ball mill. As a ratio of a pigment, the range of 5-30 mass% is preferable. In order to increase dispersibility, it is better to add a dispersant. The proportion of the dispersant varies depending on the type of the dispersant, but can be added in the range of 0.1 to 20% by mass. When the proportion of the dispersant is greater than 20% by mass, the fastness of printing tends to decrease. The average particle diameter of the pigment is preferably 50 to 200 nm.

  In the step of mixing the pigment dispersion and the resin, the pigment dispersion, the resin, the organic solvent, and the like are sufficiently mixed using a stirrer. Thereafter, a solvent-based inkjet ink composition is obtained by filtration using a 1 μm membrane filter. Thus, the solvent-based inkjet ink composition of the present invention undergoes a production process of pigment dispersion with an organic solvent and resin mixing.

  The resin dissolved in the organic solvent in the ink is ejected from the head nozzle and the solvent evaporates to form a film on the non-absorbent material, so that the pigment can be fixed and color is developed. Any resin may be used as long as the solvent is evaporated to form a film on the non-absorbent material. Examples of such resins include styrene acrylic resins, styrene maleic acid resins, epoxy resins, phenol resins, terpene phenol resins, rosin resins, rosin ester resins, acrylic resins, polyamide resins, butyral resins. Can be used depending on the physical properties of the non-absorbent material. The ratio of the resin is preferably in the range of 1 to 10% by weight in the ink.

  Various additives other than these pigments, resins and organic solvents may be used. Although the use purpose of the additive is various, it may be used, for example, to stabilize ejection in a piezo ink jet printer or to obtain good print quality. Examples of the various additives include surfactants, plasticizers, ultraviolet absorbers, light stabilizers, antioxidants, and hydrolysis inhibitors.

  The ink viscosity suitable for the piezoelectric ink jet printer is preferably 5.0 mPa · s or less, more preferably 4.5 mPa · s or less in an environment of 20 to 25 ° C. Further, the surface tension of the ink is preferably 32 mN / m or less, more preferably 30 mN / m or less in an environment of 20 to 25 ° C. The mixing ratio of pigments, resins, organic solvents, additives, and the like is adjusted so as to achieve these physical properties.

  Non-absorbable materials include plastics such as acrylic, polyethylene terephthalate (PET), polyvinyl chloride, polycarbonate, polyolefin, metals (copper, aluminum, stainless steel), glass, etc. It is not limited.

  Hereinafter, specific examples will be described. Inks and inks prepared by preparing pigment dispersions of yellow, magenta, cyan, and black and mixing them with resins, organic solvents, and the like are used as examples and comparative examples.

  In the preparation of each pigment dispersion, a dispersant (Solsperse 20000 manufactured by Avicia) is added, and the ratio of the pigment, the organic solvent, and the dispersant is the same in any dispersion. The pigment dispersion was prepared by dispersing with a sand mill at a ratio of 10% by weight of the pigment, 88% by weight of the organic solvent and 2% by weight of the dispersant, and each pigment dispersion was made by changing the pigment. As the organic solvent, 1-propanol is used. Since 1-propanol has a boiling point of 97.2 ° C. at 1 atm, it corresponds to a medium-boiling alcohol solvent.

  The yellow dispersion is C.I. I. Pigment Yellow 138 was used. The magenta dispersion is C.I. I. It was prepared using Pigment Red 122. The cyan dispersion is C.I. I. It was prepared using Pigment Blue 15: 3. The black dispersion is a C.I. I. It was prepared using Pigment Black 7.

  20% by weight of the yellow dispersion, 4% by weight of styrene acrylic resin (Joncrill 690 manufactured by BASF Japan) as a resin, and a mixed solvent (36% by weight of 1-propanol, 20% by weight of isopropanol and 20% by weight of 1-hexanol). %) In a proportion of 76% by weight using a stirrer with sufficient stirring and mixing, and filtration using a 1 μm membrane filter to obtain the solvent-based inkjet ink composition of Example 1 (yellow) Got. 1-propanol corresponds to a medium-boiling alcohol solvent, and isopropanol has a boiling point of 82.3 ° C. at 1 atm, and therefore corresponds to a low-boiling alcohol solvent. Is equivalent to a high-boiling alcohol solvent because it has a boiling point of 157.1 ° C. at 1 atmosphere. In this ink, the proportion of the organic solvent (mixed solvent) is 94% by weight, and in this organic solvent (mixed solvent), the proportion of the medium-boiling alcohol solvent (1-propanol) is 57% by weight, which is low. The proportion of the boiling alcohol solvent (isopropanol) is 21% by weight, and the proportion of the high boiling alcohol solvent (1-hexanol) is 21% by weight. In addition, the total of the alcoholic solvent in the organic solvent is not 100 weight% by rounding off.

  A solvent-based inkjet ink composition (magenta) of Example 2 was obtained in the same manner as in Example 1 except that the pigment dispersion was changed to a magenta dispersion.

  A solvent-based inkjet ink composition (cyan) of Example 3 was obtained in the same manner as in Example 1 except that the pigment dispersion was changed to a cyan dispersion.

  A solvent-based inkjet ink composition (black) of Example 4 was obtained in the same manner as in Example 1 except that the pigment dispersion was changed to a black dispersion.

  In Examples 2 to 4, the ratio of the organic solvent (mixed solvent) in the ink and the ratios of the medium boiling alcohol solvent, the low boiling alcohol solvent, and the high boiling alcohol solvent in the organic solvent (mixed solvent) are as follows: All are the same as in Example 1.

  20% by weight of the yellow dispersion, 4% by weight of styrene acrylic resin (Joncrill 690 manufactured by BASF Japan) as the resin, and 76% by weight of the mixed solvent (36% by weight of 1-propanol and 40% by weight of isopropanol) as the organic solvent. The solvent-based inkjet ink composition (Yellow) of Example 5 was obtained by mixing with sufficient stirring using a stirrer at a ratio, followed by filtration using a 1 μm membrane filter. Note that 1-propanol corresponds to a medium boiling alcohol solvent, and isopropanol corresponds to a low boiling alcohol solvent. In this ink, the proportion of the organic solvent (mixed solvent) is 94% by weight, and in this organic solvent (mixed solvent), the proportion of the medium-boiling alcohol solvent (1-propanol) is 57% by weight, which is low. The ratio of the boiling alcohol solvent (isopropanol) is 43% by weight.

  A solvent-based inkjet ink composition (magenta) of Example 6 was obtained in the same manner as in Example 5 except that the pigment dispersion was changed to a magenta dispersion.

  A solvent-based inkjet ink composition (cyan) of Example 7 was obtained in the same manner as in Example 5 except that the pigment dispersion was changed to a cyan dispersion.

  A solvent-based inkjet ink composition (black) of Example 8 was obtained in the same manner as in Example 5 except that the pigment dispersion was changed to a black dispersion.

  In Examples 6 to 8, the proportions of the organic solvent (mixed solvent) in the ink and the proportions of the medium-boiling alcohol solvent and the low-boiling alcohol solvent in the organic solvent (mixed solvent) are all as in Example 5. The same.

  20% by weight of yellow dispersion, 4% by weight of styrene acrylic resin (Joncrill 690 manufactured by BASF Japan) as resin, and 76% of mixed solvent (56% by weight of 1-propanol and 20% by weight of 1-hexanol) as organic solvent The solvent-based inkjet ink composition (yellow) of Example 9 was obtained by sufficiently stirring and mixing using a stirrer at a ratio of%, followed by filtration using a 1 μm membrane filter. 1-propanol corresponds to a medium boiling alcohol solvent, and 1-hexanol corresponds to a high boiling alcohol solvent. In this ink, the proportion of the organic solvent (mixed solvent) is 94% by weight, and in this organic solvent (mixed solvent), the proportion of the medium boiling alcohol solvent (1-propanol) is 79% by weight. The ratio of the boiling alcohol solvent (1-hexanol) is 21% by weight.

  A solvent-based inkjet ink composition (magenta) of Example 10 was obtained in the same manner as in Example 9 except that the pigment dispersion was changed to a magenta dispersion.

  A solvent-based inkjet ink composition (cyan) of Example 11 was obtained in the same manner as in Example 9 except that the pigment dispersion was changed to a cyan dispersion.

  A solvent-based inkjet ink composition (black) of Example 12 was obtained in the same manner as Example 9 except that the pigment dispersion was changed to a black dispersion.

  In Examples 10 to 12, the ratio of the organic solvent (mixed solvent) in the ink and the ratios of the medium-boiling alcohol solvent and the high-boiling alcohol solvent in the organic solvent (mixed solvent) are all as in Example 9. The same.

  Thoroughly stir using a stirrer with 20% by weight of the yellow dispersion, 4% by weight of styrene acrylic resin (Joncrill 690 manufactured by BASF Japan) as the resin, and 76% by weight of the organic solvent (1-propanol). Then, a solvent-based inkjet ink composition (yellow) of Example 13 was obtained by filtration using a 1 μm membrane filter. In this ink, the proportion of the organic solvent (medium boiling alcohol solvent) is 94% by weight, and in this organic solvent, the proportion of medium boiling alcohol solvent (1-propanol) is 100% by weight.

  A solvent-based inkjet ink composition (magenta) of Example 14 was obtained in the same manner as in Example 13 except that the pigment dispersion was changed to a magenta dispersion.

  A solvent-based inkjet ink composition (cyan) of Example 15 was obtained in the same manner as in Example 13 except that the pigment dispersion was changed to a cyan dispersion.

  A solvent-based inkjet ink composition (black) of Example 16 was obtained in the same manner as in Example 13 except that the pigment dispersion was changed to a black dispersion.

  A solvent-based inkjet ink composition (yellow) of Example 17 was obtained in the same manner as in Example 13 except that the organic solvent was changed to 1-butanol. 1-butanol has a boiling point of 117.7 ° C. at 1 atm, and therefore corresponds to a medium-boiling alcohol solvent. In Example 17, since 1-propanol is used as the organic solvent in the dispersion, the organic solvent in the ink is a mixed solvent of a medium-boiling alcohol solvent composed of 1-propanol and 1-butanol.

  A yellow dispersion was prepared in the same manner except that the organic solvent in the yellow dispersion was changed to 1-butanol. 20% by weight of the yellow dispersion using 1-butanol, 4% by weight of styrene acrylic resin (Joncrill 690 manufactured by BASF Japan Ltd.) as a resin, and 76% by weight of 1-butanol as an organic solvent. The solvent-based inkjet ink composition (Yellow) of Example 18 was obtained by using and stirring well and mixing, followed by filtration using a 1 μm membrane filter.

  In Examples 14 to 18, the ratio of the organic solvent in the ink and the ratio of the medium-boiling alcohol solvent in the organic solvent are all the same as in Example 13.

(Comparative Example 1)
A yellow dispersion was prepared in the same manner except that the organic solvent in the preparation of the yellow dispersion was changed to isopropanol. 20% by weight of the yellow dispersion using isopropanol, 4% by weight of styrene acrylic resin (Joncrill 690 manufactured by BASF Japan) as a resin, and mixed solvent (50% by weight of isopropanol and 26% by weight of 1-hexanol) as an organic solvent. The solvent-based inkjet ink composition of Comparative Example 1 was obtained by thoroughly stirring and mixing the mixture with a stirrer at a ratio of 76% by weight, followed by filtration using a 1 μm membrane filter. In this ink, the proportion of the organic solvent (mixed solvent) is 94% by weight. In this organic solvent (mixed solvent), there is no proportion of medium boiling alcohol solvent, and the proportion of low boiling alcohol solvent (isopropanol). Is 72% by weight, and the proportion of the high-boiling alcohol solvent (1-hexanol) is 28% by weight. Comparative Example 1 is different from Example 1 in the proportion of medium boiling alcohol solvent, low boiling alcohol solvent and high boiling alcohol solvent in the organic solvent (mixed solvent).

(Comparative Example 2)
20% by weight of a yellow dispersion using 1-propanol, 4% by weight of a styrene acrylic resin (Joncrill 690 manufactured by BASF Japan) as a resin, and a mixed solvent (16% by weight of 1-propanol and 60% by weight of isopropanol) as an organic solvent The solvent-based inkjet ink composition of Comparative Example 2 was obtained by mixing with sufficient stirring using a stirrer at a ratio of 76% by weight, followed by filtration using a 1 μm membrane filter. In this ink, the proportion of the organic solvent (mixed solvent) is 94% by weight, and in this organic solvent (mixed solvent), the proportion of the medium boiling alcohol solvent (1-propanol) is 36% by weight, which is low. The ratio of the boiling alcohol solvent (isopropanol) is 64% by weight. Comparative Example 2 is different from Example 5 in the proportion of medium-boiling alcohol solvent and low-boiling alcohol solvent in the organic solvent (mixed solvent).

(Comparative Example 3)
20% by weight of a yellow dispersion using 1-propanol, 4% by weight of a styrene acrylic resin (Joncrill 690 manufactured by BASF Japan) as a resin, and a mixed solvent (50% by weight of 1-propanol and 1-hexanol 26) as an organic solvent. The solvent-based inkjet ink composition of Comparative Example 3 was obtained by thoroughly stirring and mixing using a stirrer at a ratio of 76% by weight, followed by filtration using a 1 μm membrane filter. It was. In this ink, the proportion of the organic solvent (mixed solvent) is 94% by weight, and in this organic solvent (mixed solvent), the proportion of the medium boiling alcohol solvent (1-propanol) is 72% by weight. The ratio of the boiling alcohol solvent (1-hexanol) is 28% by weight. Comparative Example 3 is different from Example 9 in the proportion of the medium-boiling alcohol solvent and the high-boiling alcohol solvent in the organic solvent (mixed solvent).

  The ink viscosities in the solvent-based inkjet ink compositions of Examples 1 to 18 and Comparative Examples 1 to 3 thus obtained were all 4.5 mPa · s or less in an environment of 20 to 25 ° C., The surface tension of the ink was all 30 mN / m or less in an environment of 20 to 25 ° C., which was a physical property suitable for a piezo ink jet printer. These inks were used to evaluate printer parts for erosion (shape change, weight change), printability (bleed, dot missing, flying bend), drying after printing, and printing fastness. The evaluation methods and the evaluation results (Table 1) are shown below.

<Erosion property>
As an evaluation of the erodibility of the printer parts, parts in contact with the ink in the printer were taken out and immersed in each ink at 50 ° C. for one month, and the subsequent shape change and weight change were evaluated. The evaluation of the change in shape was made by observation, and it was indicated as ◯ when there was no change in the shape, and × when there was a change. The weight change was evaluated by measuring the rate of change of the weight of each component and ◯ when the average rate of change was less than 5%, and x when the rate of change was 5% or more.

<Printability>
For evaluation of printability, a non-absorbent material (acrylic plate, aluminum plate, glass plate) that does not have an ink receiving layer is used to print a test pattern including letters and solids, and bleeding and dot missing And the flight bend was evaluated by observation. The evaluation of bleeding was evaluated as ◯ when there was no bleeding in the test pattern, and X when there was bleeding. The evaluation of the dot defect that occurs because the ink was not ejected from the printer was evaluated as ◯ when the test pattern had no dot defect, and × when the dot defect was present. The evaluation of the flight bend in which the ejected ink did not land at an appropriate location was evaluated as ◯ when there was no flight bend in the test pattern, and x when there was a flight bend.

<Drying>
As an evaluation of the drying property after printing, it was evaluated based on the presence or absence of ink transfer by pressure bonding with a rubber roller. Using a non-absorbing material (acrylic plate, aluminum plate, glass plate) that is not provided with an ink receiving layer, a plain paper is overlaid on a solid test piece after 10 minutes of printing in a 25 ° C environment. A rubber roller (with a rubber roll width of 12 cm and a rubber roll diameter of 2 cm) on which a load of 1 kg was placed was rolled and pressed to observe the ink transfer. The dryness was evaluated as “◯” when there was no ink transfer to plain paper, and “X” when there was ink transfer.

<Robustness>
As an evaluation of the fastness of printing, it was evaluated with a friction tester. Solid printing using a non-absorbing material (acrylic plate, aluminum plate, glass plate) without an ink receiving layer using a Sauzaland-type love tester (manufactured by Yasuda Seiki Seisakusho) as a friction tester. A friction test was carried out on the test piece subjected to 100 reciprocations under a load of 9.39 × 10 ³ Pa applied with a cotton cloth, and the lack of printing was observed. In the evaluation of the robustness, “O” indicates no omission in solid printing, and “X” indicates omission in partial printing.

  In Examples 1 to 18, good results were obtained in each evaluation of the erosion property, printability, drying property after printing, and printing fastness of the printer parts. As a result, it is possible to provide a solvent-based inkjet ink composition that has solved the problem.

  In Comparative Example 1, there is no medium-boiling point alcohol solvent, and both the low-boiling point alcohol solvent and the high-boiling point alcohol solvent are large, and problems due to both of them occur. In Comparative Example 2, the medium-boiling point alcohol solvent is small and the low-boiling point alcohol solvent is large, resulting in problems due to the low-boiling point alcohol solvent. In the comparative example 3, there are many high boiling alcohol solvents, and the malfunction by the high boiling alcohol solvent has come out.

  Using non-absorbing materials (acrylic plate, aluminum plate, and glass plate) that are not provided with an ink-receptive layer, the combination of three colors consisting of yellow, magenta, and cyan up to Examples 1 to 3 was carried out. When a full-color image was printed with a combination of four colors including the black of Example 4, a good full-color print image could be obtained. Further, a combination of three colors consisting of yellow, magenta and cyan in Examples 5 to 7 and a combination of four colors obtained by adding black in Example 8 to these, consisting of yellow, magenta and cyan in Examples 9 to 11 A combination of three colors and a combination of four colors obtained by adding the black of Example 12 to these, a combination of three colors consisting of yellow, magenta, and cyan of Examples 13 to 15 and a combination of the three colors consisting of yellow of magenta and cyan 4 When a full color image was printed even with a combination of colors, a good full color print image could be obtained in all cases.

Claims (2)

In the solvent-based inkjet ink composition for non-absorbent materials used in piezo inkjet printers, it consists at least of pigment, resin, organic solvent,
In the ink, the proportion of the organic solvent is 90% by weight or more, the organic solvent is an alcohol solvent, the boiling point at 1 atm is 90 ° C. to 140 ° C. A low boiling alcohol solvent having a boiling point of less than 90 ° C. and / or a high boiling alcohol solvent having a boiling point of greater than 140 ° C. at 1 atmosphere,
In the organic solvent, the proportion of the medium boiling alcohol solvent is 40% by weight or more, the proportion of the low boiling alcohol solvent is 60% by weight or less, and the proportion of the high boiling alcohol solvent is 25% by weight or less. A solvent-based inkjet ink composition characterized by the above.   2. The solvent-based inkjet ink composition according to claim 1, wherein the ink is for full-color printing using a combination of at least three colors consisting of yellow, magenta, and cyan, or a combination of at least four colors obtained by adding black to these. object.