JP7196526B2 - Printed matter manufacturing method - Google Patents

Description

The present invention relates to a method for producing a printed matter by an inkjet recording method.

The inkjet recording method is a recording method in which ink (ink droplets) is directly ejected from extremely fine nozzles onto a recording medium to adhere the ink to obtain characters and images. According to this method, not only are the advantages of low noise and good operability of the device used, colorization is easy, and this method is widely used as an output machine in offices, homes, etc. there is

In the industrial world, methods of printing on recording media such as packaging materials and advertising media using inkjet printers are being studied. As an ink that can be used for printing on a recording medium, for example, an aqueous emulsion resin having a glass transition point of 16° C. or higher and an acid value of 10 mgKOH/g or higher and a pigment are combined so that the solid content is 15% by weight or higher. and an aminoalcohol as a dispersion stabilizer (see, for example, Patent Document 1 below).

JP 2011-12226 A

There are many types of recording media, and known examples include plastic films and corrugated cardboard (corrugated cardboard sheets) in which corrugated paperboard is sandwiched between two paperboards.

When using a recording medium (plastic film, etc.) that does not easily absorb the solvent (water, organic solvent, etc.) contained in the ink, make sure that the solvent dries quickly after the ink lands on the surface (recording surface) of the recording medium. In some cases, a method of warming the recording medium is used. However, when the recording medium is warmed, the ink-jet head located near the surface (recording surface) of the recording medium is also warmed, so the ink adhering to the ink ejection nozzles is more likely to dry. Due to nozzle clogging and abnormalities in the direction of ink ejection, symptoms generally referred to as nozzle clogging, twisting, and the like tend to occur.

Also, when printing on a recording medium such as plastic film or cardboard by the inkjet recording method, the ink discharge nozzle and the recording medium may be affected by warping of the recording medium or unevenness of the surface caused by the corrugated paperboard that makes up the corrugated board. may come into contact with each other and cause problems.

As a method of preventing the problem caused by the drying of the ink ejection nozzles and the contact between the ink ejection nozzles and the recording medium, it is conceivable to set a long distance between the inkjet head and the recording medium. However, when the distance is increased, the distance required for the ink ejected from the ink ejection port of the inkjet head to land on the surface of the recording medium is generally increased. For reasons such as the tendency to excessively occur, problems such as streaks may occur in the printed matter.

Further, in printing by the inkjet recording method, in order to improve the image quality of printed matter, efforts are being made to increase the resolution of printed matter from the conventional 600 dpi to 1000 dpi or more (for example, 1200 dpi). In order to obtain a printed matter of 1000 dpi or more, it is necessary to eject droplets that are smaller than the droplets that are ejected when obtaining a printed matter of 600 dpi. Such small droplets of ink are smaller in size than the droplets ejected when producing 600 dpi printed matter, so they tend to dry in the vicinity of the ink ejection nozzles. Distortion (the ejection direction is bent and the ink lands in a position different from the original) is likely to occur, and as a result, streaks are likely to occur on the printed matter. The printing accuracy when printing again later) tends to decrease. Therefore, for printing by the inkjet recording method, even if the distance between the ink ejection port of the inkjet head and the recording medium is long at a resolution of 1000 dpi or more, the occurrence of streak-like printing defects is suppressed. It is required to obtain excellent ejection stability as well as to be able to do so.

The problem to be solved by the present invention is to suppress the occurrence of streak-like printing defects in an inkjet recording method with a resolution of 1000 dpi or more even when the distance between the ink ejection port of the inkjet head and the recording medium is long. To provide a method for manufacturing a printed matter capable of obtaining excellent ejection stability.

A method for producing a printed matter according to one aspect of the present invention includes a printing step for obtaining a printed matter by printing ink on a recording medium by an inkjet recording method with a resolution of 1000 dpi or higher, and in the printing step, ink ejection openings of an inkjet head. and the recording medium is 2 mm or more, the ink contains a pigment and a resin component, and the total amount of the pigment and the resin component is more than 0% by mass and 13% by mass with respect to the total amount of the ink % or less, and the viscosity of the ink at 32° C. is 5 mPa·s or less.

According to the present invention, even when the distance between the ink ejection port of the inkjet head and the recording medium is long in an inkjet recording method with a resolution of 1000 dpi or more, it is possible to suppress the occurrence of streak-like printing defects, and it is excellent. (Ejection stability in a long-term printing test. For example, an effect of suppressing streak-like printing defects when printing is resumed after a certain period of time has elapsed) can be obtained.

It is a schematic diagram of a microreactor.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail. In this specification, "(meth)acrylic acid" is a general term for acrylic acid and methacrylic acid corresponding thereto, and the same applies to other similar expressions such as "(meth)acrylate". .

The method for producing a printed matter according to the present embodiment includes a printing step of obtaining a printed matter by printing ink on a recording medium (printing medium) by an inkjet recording method with a resolution of 1000 dpi or more, and in the printing step, the inkjet head The shortest distance D between the ink ejection port and the recording medium is 2 mm or more, the ink contains a pigment and a resin component, and the total amount of the pigment and the resin component is 0% by mass with respect to the total amount of the ink. and 13% by mass or less, and the viscosity of the ink at 32° C. is 5 mPa·s or less.

According to this method for producing a printed matter, even when the distance between the ink ejection port of the inkjet head and the recording medium is long (when the shortest distance is 2 mm or more) in an inkjet recording method (inkjet printing method) with a resolution of 1000 dpi or more, Even if there is, the occurrence of streak-like printing defects can be suppressed, and excellent ejection stability can be obtained.

When the distance between the ink ejection port of the inkjet head and the recording medium is short (for example, when the shortest distance is 1 mm), even if the ink droplets are skewed, the landing position of the ink will be the target of printing on the recording medium. It is difficult to deviate from the position. On the other hand, when the distance between the ink ejection port of the inkjet head and the recording medium is long (when the shortest distance is 2 mm or more), the flight distance of the ink droplets is long, so the ink landing position is the print target position on the recording medium. It is easy to deviate from
Further, when the resolution is 1000 dpi or more, since the size of the ink droplets is small, the ink tends to dry in the vicinity of the ink discharge nozzle, which is likely to cause problems. In addition, since the droplet size is small, printing defects such as streaks are likely to occur when the landing position of the ink is slightly deviated.
On the other hand, in the present embodiment, the total amount of the pigment and the resin component is within the above range and the viscosity of the ink is within the above range. This improves the accuracy (straightness of ejection) of landing the ink on the printing target position of the recording medium. In addition, the ejection speed of the droplets is improved, and the wetting and spreading of the ink during drying after landing is improved. As a result, it is possible to suppress the occurrence of streak-like printing defects.
In addition, since the total amount of the pigment and the resin component is within the above range, it is easy to prevent the ink from drying as described above, so that the deterioration of the ejection stability in the long-term printing test is suppressed. Thereby, excellent ejection stability can be obtained.
However, the factor for obtaining the above effect is not limited to this factor.

Conventionally, non-absorbent or non-absorbent (slowly absorbent) recording media such as corrugated board, which has a colored layer on the surface of paperboard that does not readily absorb the solvent in the ink, and plastic films, have been used as recording media. When used, the landed ink is less likely to be absorbed by the recording medium and less likely to spread on the surface of the recording medium, resulting in streak-like printing defects. On the other hand, according to the present embodiment, it is possible to suppress the occurrence of streak-like printing defects even when using a non-absorbent or non-absorbent recording medium.

Furthermore, in the present embodiment, since the shortest distance D is 2 mm or more, it is possible to prevent the surface (recording surface) of the recording medium from coming into contact with the ink discharge ports even if the recording medium is large and easily warped. It is possible to effectively prevent ink ejection defects caused by damage to the ink ejection openings and deterioration of the water-repellent function that is often provided in the ink ejection openings.

The shortest distance D may be 3 mm or more. The shortest distance D is preferably 10 mm or less, more preferably 5 mm or less, from the viewpoint of easily suppressing the occurrence of streak-like printing defects. The shortest distance D is from the surface (x) having the ink ejection openings of the inkjet head to the position (y) where the normal to the surface (x) (perpendicular to the surface (x)) intersects the recording medium. may be a distance (gap) of

The resolution in the inkjet recording method may be 1100 dpi or more, or 1200 dpi or more, from the viewpoint of improving the image quality of printed matter. The resolution in the inkjet recording method may be 2400 dpi or less.

In this embodiment, in the inkjet recording method with a resolution of 1000 dpi or more, the ejection amount of one ink droplet is preferably 0.5 to 5 pL or less, more preferably 0.5 to 3 pL or less, and even more preferably 0.5 to 2 PL. A small droplet is preferable because a high-definition image can be obtained when the ejection amount is small.

The recording medium (for example, the recording surface of the recording medium) in the printing process may be warmed. Further, the method for manufacturing a printed matter according to the present embodiment may include a heating step of warming the recording medium (for example, the recording surface of the recording medium) after the printing step. The temperature of the recording medium in these cases is such that streaks and color mixture do not occur when ink lands on the surface of the recording medium even when the distance between the ink ejection port of the inkjet head and the recording medium is long. From the viewpoint of easy production of suppressed prints, the temperature is preferably 20 to 80°C, more preferably 25 to 80°C, even more preferably 40 to 80°C, particularly preferably 40 to 60°C, and extremely preferably 40 to 50°C. The temperature of the recording medium may have these temperatures without being intentionally warmed.

As a method for adjusting the temperature of the recording medium, for example, a method of directly irradiating infrared rays, microwaves, etc. from the printing surface side (upper surface side), lower surface side, or side surface side of the recording medium to heat it; A method of heating by applying wind heated by waves or the like can be mentioned. Further, as the adjustment method, for example, a stage, a carriage, a carriage roll, or the like on which the recording medium is placed is heated by a heating wire, infrared rays, microwaves, hot air, or the like, and the heat is applied to the recording medium. A method of transferring heat to Specifically, examples of the adjusting method include a method using a transport roll (heat roller) provided with heating means such as a heating wire, a transport stand, a stage, or the like.

Heating methods using infrared rays include, for example, a halogen heater using a tungsten wire, a quartz tube heater using a nichrome wire, and a method using a radiant heat dryer equipped with a carbon heater. A method using a radiant heat dryer equipped with a high efficiency short-wave infrared heater, medium-wave infrared heater, medium-wave carbon heater, or the like is preferred.

The viscosity at 32° C. of the ink according to the present embodiment (the ink that can be used in the inkjet recording method in the method for producing a printed matter according to the present embodiment) is 5 mPa·1 from the viewpoint of suppressing the occurrence of streak-like printing defects. s or less. The viscosity of the ink is preferably less than 5 mPa·s, more preferably 4.5 mPa·s or less, even more preferably 4 mPa·s or less, and 3.7 mPa·s from the viewpoint of easily suppressing the occurrence of streak-like printing defects. s or less is particularly preferable, and 3.6 mPa·s or less is extremely preferable. The viscosity of the ink is preferably 1 mPa·s or more, more preferably 1.5 mPa·s or more, still more preferably 2 mPa·s or more, and 2.5 mPa·s or more, from the viewpoint of easily suppressing the occurrence of streak-like printing defects. s or more is particularly preferred, and 3 mPa·s or more is extremely preferred. From these points of view, the ink viscosity is preferably 1 to 5 mPa·s, more preferably 2 to 4 mPa·s.

The viscosity of the ink can be measured using a cone-plate (cone-plate) rotational viscometer equivalent to an E-type viscometer under the following conditions.
Measuring device: TVE-25 type viscometer (manufactured by Toki Sangyo Co., Ltd., TVE-25 L)
Calibration standard solution: JS20
Measurement temperature: 32°C
Rotation speed: 10-100rpm
Injection volume: 1200 μL

The static surface tension of the ink according to the present embodiment is preferably 25 mN/m or more, more preferably 26 mN/m or more, and further preferably 28 mN/m or more, from the viewpoint of easily suppressing the occurrence of streak-like printing defects. Preferably, 28.5 mN/m or more is particularly preferable. The static surface tension of the ink is preferably 35 mN/m or less, more preferably 32 mN/m or less, even more preferably 31 mN/m or less, from the viewpoint of easily suppressing the occurrence of streak-like printing defects. The following are particularly preferred, with 29.5 mN/m or less being extremely preferred, and 29 mN/m or less being very preferred. From these points of view, the static surface tension of the ink is preferably 25 to 35 mN/m. The static surface tension of the ink is the static surface tension at 25°C. By using an acetylenic surfactant, it is easy to obtain the above-mentioned suitable surface tension.

The static surface tension of ink can be measured using an automatic surface tension meter to which the Wilhelmy method is applied under the following conditions.
Measuring device: Automatic surface tensiometer (manufactured by Kyowa Interface Science Co., Ltd., CBVP-Z type)
Measurement temperature: 25°C
Probe: Platinum plate

The pH of the ink according to the present embodiment tends to improve the storage stability and ejection stability of the ink, and wet spread, print density, and abrasion resistance when printing on an ink non-absorbent or non-absorbent recording medium. is preferably 7.0 or more, more preferably 7.5 or more, and still more preferably 8.0 or more, from the viewpoint of easily improving the The upper limit of the pH of the ink according to the present embodiment makes it easy to suppress the deterioration of the members (ink ejection port, ink flow path, etc.) that constitute the ink application or ejection device, and the influence when the ink adheres to the skin. is preferably 11.0 or less, more preferably 10.5 or less, and still more preferably 10.0 or less, from the viewpoint of easily reducing the

The ink according to this embodiment can be used as an inkjet ink. The ink according to this embodiment contains a pigment and a resin component. The pigment may be coated with a resin component.

The pigment is not particularly limited, and inorganic or organic pigments commonly used in water-based gravure inks and water-based inkjet recording inks can be used. Examples of inorganic pigments that can be used include iron oxide and carbon black produced by a contact method, furnace method, thermal method, or the like. Examples of organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, etc.), polycyclic pigments (phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinoflurone pigments, etc.), lake pigments (basic dye-type chelates, acid dye-type chelates, etc.), nitro pigments, nitroso pigments, aniline black and the like can be used. As the pigment, both non-acid-treated pigments and acid-treated pigments can be used.

Among the above pigments, examples of carbon black that can be used for black ink include No. 2300, No. 2200B, No. 900, No. 960, No. 980, No. 33, No. 40, No, 45, No. 45L, No. 52, HCF88, MA7, MA8, MA100, etc.; Columbia's Raven5750, Raven5250, Raven5000, Raven3500, Raven1255, Raven700, etc.; , Monarch900, Monarch1000, Monarch1100, Monarch1300, Monarch1400, etc.; Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, V, 1400U, Special Black 6, 5, 4, 4A, NIPEX150, NIPEX160, NIPEX170, NIPEX180, etc. can be used.

Specific examples of pigments that can be used in yellow ink include C.I. I. Pigment Yellow 1, 2, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 120, 128, 129, 138, 150, 151, 154, 155, 174, 180, 185 and the like. Specific examples of pigments that can be used in magenta ink include C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57:1, 112, 122, 123, 146, 176, 184, 185, 202, 209, 269, 282, etc.; C. I. Pigment Violet 19 and the like. Specific examples of pigments that can be used in cyan ink include C.I. I. Pigment Blue 1, 2, 3, 15, 15:3, 15:4, 16, 22, 60, 63, 66 and the like.

Specific examples of pigments that can be used in white ink include silicas, calcium silicate, alumina, alumina hydrate, titanium oxide, zinc oxide, talc, and clay. These may be surface-treated.

In order for the pigment to stably exist in the ink, it is preferable to take measures to disperse it well in an aqueous medium. Examples of the means include (i) a method of dispersing a pigment together with a pigment dispersant in an aqueous medium by a dispersing method described later; (ii) dispersibility imparting groups (hydrophilic functional groups and/or salt) directly or indirectly via an alkyl group, an alkyl ether group, an aryl group or the like, and dispersing and/or dissolving the self-dispersing pigment in an aqueous medium.

As the self-dispersing pigment, for example, a pigment is subjected to a physical or chemical treatment to bond (graft) a dispersibility-imparting group or an active species having a dispersibility-imparting group to the surface of the pigment. can do. For self-dispersing pigments, for example, vacuum plasma treatment, oxidation treatment with hypohalous acid and/or hypohalite; oxidation treatment with ozone; wet oxidation method in which the pigment surface is oxidized with an oxidizing agent in water; p-amino By bonding benzoic acid to the pigment surface, it can be produced by a method of bonding a carboxyl group via a phenyl group, or the like.

Since the water-based ink containing the self-dispersing pigment does not need to contain a pigment dispersant, there is almost no foaming caused by the pigment dispersant, and it is easy to prepare an ink with excellent ejection stability. In addition, water-based inks containing self-dispersing pigments are easy to handle and suppress a significant increase in viscosity caused by pigment dispersants. Can be used in manufacturing.

Commercially available products can be used as the self-dispersing pigment, and examples of such commercial products include Microjet CW-1 (trade name, manufactured by Orient Chemical Industry Co., Ltd.), CAB-O-JET200, and CAB. -O-JET300 (trade name, manufactured by Cabot Corporation) and the like.

The content of the pigment is based on the total amount of the ink from the viewpoint of easily preventing the occurrence of streaks, maintaining the excellent dispersion stability of the pigment, and easily improving the print density and abrasion resistance of the printed matter. is preferably 0.5 to 20% by mass, more preferably more than 0.5% by mass and 20% by mass or less, still more preferably 1 to 20% by mass, particularly preferably 1.5 to 15% by mass, and 2 to 10% by mass. % by weight is highly preferred, 3-8% by weight is very preferred, and 3-6% by weight is even more preferred.

Examples of resin components include pigment dispersants and binder resins.

Examples of pigment dispersants include polyvinyl alcohols; polyvinylpyrrolidones; acrylic resins such as acrylic acid-acrylic acid ester copolymers; styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid -Styrene-acrylic resins such as acrylic acid ester copolymers, styrene-α-methylstyrene-acrylic acid copolymers, styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymers; styrene-maleic acid copolymers; Aqueous resins such as coalescence, styrene-maleic anhydride copolymer, vinyl naphthalene-acrylic acid copolymer; salts of the above aqueous resins, and the like can be used. As a pigment dispersant, Ajinomoto Fine Techno Co., Ltd. Ajisper PB series, BYK-Chemie Japan Co., Ltd. Disperbyk series, BASF EFKA series, Nippon Lubrizol Co., Ltd. SOLSPERSE series, Evonik TEGO series. etc. can be used.

As the pigment dispersant, the following polymer P is preferable from the viewpoint that coarse particles can be significantly reduced and, as a result, it is easy to impart good ejection stability required when ink is ejected by an ink jet recording method.

As the polymer P, those having an anionic group can be used. Among them, the solubility in water is 0.1 g / 100 mL or less, and the number average molecular weight is 1000 to 6000, which is capable of forming fine particles in water when the neutralization rate of the anionic group with a basic compound is 100%. It is preferred to use polymers of

The solubility of polymer P in water can be defined as follows. That is, first, 0.5 g of polymer P whose particle size was adjusted to a range of 250 μm to 90 μm using sieves with mesh openings of 250 μm and 90 μm was sealed in a bag processed with a 400 mesh wire mesh, immersed in 50 mL of water, and heated at 25 ° C. Leave under mild stirring for 24 hours at temperature. After soaking for 24 hours, the 400-mesh wire mesh encapsulating the polymer P is dried for 2 hours in a dryer set at 110°C. The change in mass of the 400-mesh wire mesh enclosing the polymer P before and after immersion in water is measured, and the solubility is calculated by the following equation.
Solubility [g / 100 mL] = (polymer-encapsulated 400-mesh wire mesh [g] before immersion - polymer-encapsulated 400-mesh wire mesh [g] after immersion) × 2

Whether or not fine particles are formed in water when the rate of neutralization of anionic groups by a basic compound is 100% can be determined as follows.
(1) The acid value of polymer P is measured in advance by the acid value measurement method based on JIS test method K 0070-1992. Specifically, 0.5 g of polymer P is dissolved in tetrahydrofuran, and the acid value is determined by titration with 0.1 M potassium hydroxide alcohol solution using phenolphthalein as an indicator.
(2) After adding 1 g of polymer P to 50 mL of water, 0.1 mol/L potassium hydroxide aqueous solution is added to neutralize the resulting acid value by 100%, to achieve 100% neutralization.
(3) Irradiate the 100% neutralized liquid with ultrasonic waves in an ultrasonic cleaner (manufactured by SND Co., Ltd., ultrasonic cleaner US-102, 38 kHz self-oscillation) at a temperature of 25 ° C. for 2 hours. After that, it is left at room temperature for 24 hours.

After standing for 24 hours, the liquid at a depth of 2 cm from the liquid surface was used as a sample liquid, and a dynamic light scattering particle size distribution measuring device (manufactured by Nikkiso Co., Ltd., a dynamic light scattering particle size measuring device "Microtrac particle size distribution The presence of fine particles is confirmed by determining whether light scattering information due to fine particle formation can be obtained using a total UPA-ST150").

From the viewpoint of further improving the stability of the fine particles formed by the polymer P in water, the particle diameter of the fine particles is preferably 5 to 1000 nm, more preferably 7 to 700 nm, and even more preferably 10 to 500 nm. In addition, the narrower the particle size distribution of the fine particles, the better the dispersion stability. However, even when the particle size distribution is wide, an ink having better dispersion stability than conventional inks can be obtained. In addition, the particle size and particle size distribution can be measured using a dynamic light scattering particle size distribution measuring device (manufactured by Nikkiso Co., Ltd., a dynamic light scattering particle size measuring device "Microtrac Particle Size Distribution Meter") in the same manner as the method for measuring fine particles. UPA-ST150”).

The neutralization rate of polymer P can be determined by the following formula.
Neutralization rate (%) = {(mass of basic compound [g] x 56 x 1000)/(acid value of polymer P [mgKOH/g] x equivalent weight of basic compound x mass of polymer P [g])} ×100

The acid value of polymer P can be measured according to JIS test method K 0070-1992. Specifically, it can be determined by dissolving 0.5 g of a sample in tetrahydrofuran and titrating with a 0.1 M potassium hydroxide alcohol solution using phenolphthalein as an indicator.

The number-average molecular weight of the polymer P is preferably 1000 to 6000 from the viewpoint of effectively suppressing aggregation of a coloring material such as a pigment in an aqueous medium and easily obtaining an ink having good dispersion stability of the coloring material. , 1300 to 5000 are more preferred, and 1500 to 4500 are even more preferred. The number average molecular weight is a polystyrene-equivalent value measured by GPC (gel permeation chromatography), and specifically, a value measured under the following conditions.

[Method for measuring number average molecular weight (Mn)]
It was measured under the following conditions by a gel permeation chromatography (GPC) method.
Measuring device: high-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation are connected in series and used.
"TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 Book "TSKgel G2000" (7.8 mm ID x 30 cm) x 1 Detector: RI (differential refractometer)
Column temperature: 40°C
Eluent: Tetrahydrofuran Flow rate: 1.0 mL/min Injection volume: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4% by mass)
Standard sample: Create a calibration curve using the following standard polystyrene.
{standard polystyrene}
"TSKgel standard polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-550" manufactured by Tosoh Corporation

As the polymer P, a polymer that is insoluble or sparingly soluble in water in an unneutralized state and forms fine particles in a 100% neutralized state can be used. A polymer having a hydrophobic group in one molecule in addition to the functional group can be used.

Examples of such polymers include block polymers having a polymer block having a hydrophobic group and a polymer block having an anionic group. In the polymer P, the number of anionic groups and the solubility in water are not necessarily specified by the acid value or the number of anionic groups at the time of polymer design. Even if there is, those with a low molecular weight tend to have a high solubility in water, and those with a high molecular weight tend to have a low solubility in water. From this, the polymer P is specified by its solubility in water.

The polymer P may be a homopolymer, preferably a copolymer, and may be a random polymer, a block polymer, an alternating polymer, but especially a block polymer. is preferred. Moreover, the polymer P may be a branched polymer, but is preferably a linear polymer.

The polymer P is preferably a vinyl polymer from the viewpoint of freedom of design. As a method for producing a vinyl polymer having a desired molecular weight and solubility characteristics, living radical polymerization, living cationic polymerization, and living anionic polymerization can be used. It is preferable to manufacture by using "polymerization".

Among them, the polymer P is preferably a vinyl polymer produced using a (meth)acrylate monomer as one of raw materials, and the method for producing such a vinyl polymer is preferably living radical polymerization or living anionic polymerization. Furthermore, living anionic polymerization is preferable from the viewpoint of more precise design of the molecular weight of the block polymer and each segment.

Specifically, a polymer represented by the following general formula (c1) can be used as the polymer P produced by living anionic polymerization.

In general formula (c1), A ¹ represents an organolithium initiator residue, A ² represents a polymer block having a hydrophobic group, A ³ represents a polymer block having an anionic group, and n is , represents an integer of 1 to 5, and B represents an aromatic group or an alkyl group.

In general formula (c1), A1 represents ^an organolithium initiator residue. Specific examples of organic lithium initiators (polymerization initiators) include methyllithium, ethyllithium, propyllithium, butyllithium (n-butyllithium, sec-butyllithium, iso-butyllithium, tert-butyllithium, etc.), pentyl Alkyllithium such as lithium, hexyllithium, methoxymethyllithium, ethoxymethyllithium; benzyllithium, α-methylstyryllithium, 1,1-diphenyl-3-methylpentyllithium, 1,1-diphenylhexyllithium, phenylethyl Phenylalkylenelithium such as lithium; Alkenyllithium such as vinyllithium, allyllithium, propenyllithium and butenyllithium; Alkynyllithium such as ethynyllithium, butynyllithium, pentynyllithium and hexynyllithium; Phenyllithium and naphthyllithium aryllithium; heterocyclic lithium such as 2-thienyllithium, 4-pyridyllithium and 2-quinolyllithium; and alkyllithium magnesium complexes such as tri(n-butyl)magnesiumlithium and trimethylmagnesiumlithium.

In the organolithium initiator, the bond between the organic group and lithium is cleaved to generate an active terminal on the side of the organic group, from which polymerization is initiated. Therefore, organic groups derived from organolithium are bonded to the ends of the obtained polymer. In this specification, the organolithium-derived organic group attached to the polymer terminal is referred to as "organolithium initiator residue". For example, in the case of a polymer using methyllithium as an initiator, the organolithium initiator residue will be a methyl group, and in the case of a polymer using butyllithium as an initiator, the organolithium initiator residue will be a butyl group. .

In general formula (c1), ^A2 represents a polymer block having a hydrophobic group. A ² is preferably a group that is highly adsorbed to the pigment when in contact with the pigment, in addition to the purpose of balancing the appropriate solubility as described above. From the same viewpoint, A ² is an aromatic ring or A polymer block having a structural unit derived from a monomer having a heterocycle is preferred. A polymer block having a structural unit derived from a monomer having an aromatic ring or a heterocyclic ring is specifically a monomer having an aromatic ring such as a styrene-based monomer, or a monomer having a heterocyclic ring such as a vinylpyridine-based monomer. is a polymer block of a homopolymer or copolymer obtained by homopolymerizing or copolymerizing the

Examples of monomers having an aromatic ring include styrene, p-tert-butyldimethylsiloxystyrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, p-tert-butoxystyrene, m-tert-butoxystyrene, Styrenic monomers such as p-tert-(1-ethoxymethyl)styrene, m-chlorostyrene, p-chlorostyrene, p-fluorostyrene, α-methylstyrene, p-methyl-α-methylstyrene, vinyl naphthalene, vinylanthracene and the like. Monomers having a heterocyclic ring include vinylpyridine-based monomers such as 2-vinylpyridine and 4-vinylpyridine. Each of the monomers having an aromatic ring or heterocyclic ring can be used singly or in combination of two or more.

^In general formula (c1), A3 represents a polymer block having an anionic group. A3 has the purpose of imparting appropriate solubility as described above ^, and also the purpose of imparting dispersion stability in water when it becomes a pigment dispersion.

Examples of the anionic group in the polymer block A3 include carboxyl group ^, sulfonic acid group and phosphoric acid group. Among them, a carboxyl group is preferable from the viewpoints of ease of preparation, variety of monomer types, availability, and the like. Also, two carboxyl groups may be intramolecular or intermolecular dehydration-condensed acid anhydride groups.

The method of introducing the anionic group of A3 is not particularly limited. For example ^, when the anionic group is a carboxyl group, a homopolymer or copolymer obtained by homopolymerizing (meth)acrylic acid or copolymerizing it with another monomer may be the polymer block (PB1) of, by deprotection, a homopolymer obtained by homopolymerizing (meth)acrylate having a regeneratable protecting group on the anionic group or copolymerizing it with another monomer Alternatively, it may be a polymer block (PB2) in which some or all of the protective groups regeneratable to the anionic groups of the copolymer are regenerated to anionic groups.

Specific examples of the (meth)acrylic acid and (meth)acrylate used in the polymer block A3 include ⁽ meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, and (meth)acrylic acid. iso-propyl, allyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, (meth)acrylate n-amyl acrylate, iso-amyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-lauryl (meth)acrylate , n-tridecyl (meth)acrylate, n-stearyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-tert-butyl (meth)acrylate Cyclohexyl, isobornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentadienyl (meth)acrylate, adamantyl (meth)acrylate, glycidyl (meth)acrylate, tetrahydro (meth)acrylate Furfuryl, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, trifluoroethyl (meth)acrylate, ( meth)tetrafluoropropyl acrylate, pentafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, pentadecafluorooctyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, N,N- Dimethyl (meth)acrylamide, (meth)acryloylmorpholine, (meth)acrylonitrile, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, polyethylene glycol-polypropylene glycol (meth) acrylate, polyethylene glycol-polybutylene glycol (meth) Acrylate, polypropylene glycol-polybutylene glycol (meth)acrylate, methoxypolyethyleneglycol (meth)acrylate, ethoxypolyethyleneglycol (meth)acrylate, butoxypolyethyleneglycol (meth)acrylate, octoxypolyethyleneglycol (meth)acrylate Polyethylene glycol (meth)acrylate such as lauroxypolyethyleneglycol (meth)acrylate, stearoxypolyethyleneglycol (meth)acrylate, phenoxypolyethyleneglycol (meth)acrylate, methoxypolypropyleneglycol (meth)acrylate, octoxypolyethyleneglycol-polypropyleneglycol (meth)acrylate, etc. Alkylene oxide group-containing (meth)acrylates and the like are included. These monomers can be used individually by 1 type or in mixture of 2 or more types.

In the living anionic polymerization method, if the monomer used has a group with an active proton such as an anionic group, the active terminal of the living anionic polymer immediately reacts with the group with an active proton and deactivates. , the polymer is difficult to obtain. In living anionic polymerization, it is difficult to polymerize a monomer having a group with an active proton as it is. It is preferred to regenerate the bearing groups.

For this reason, it is preferable to use a (meth)acrylate ^- containing monomer having a protective group that can be regenerated to an anionic group by deprotection in the polymer block A3. By using the monomer, the aforementioned inhibition of polymerization can be prevented during polymerization. An anionic group protected by a protecting group can be regenerated to an anionic group by deprotecting after obtaining a block polymer.

For example, when the anionic group is a carboxyl group, the carboxyl group can be regenerated by esterifying the carboxyl group and deprotecting it by hydrolysis or the like in a subsequent step. In this case, the protecting group convertible to a carboxyl group is preferably a group having an ester bond, such as a primary alkoxycarbonyl such as a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, and an n-butoxycarbonyl group. Group; secondary alkoxycarbonyl group such as isopropoxycarbonyl group and sec-butoxycarbonyl group; tertiary alkoxycarbonyl group such as t-butoxycarbonyl group; phenylalkoxycarbonyl group such as benzyloxycarbonyl group; ethoxyethylcarbonyl group and alkoxyalkylcarbonyl groups such as

When the anionic group is a carboxyl group, usable monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, sec - butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate (lauryl (meth) ) acrylate), tridecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate (stearyl (meth) acrylate), nonadecyl (meth) acrylate, icosanyl (meth) acrylate) ) acrylate and other alkyl (meth)acrylates; benzyl (meth)acrylate and other phenylalkylene (meth)acrylates; ethoxyethyl (meth)acrylate and other alkoxyalkyl (meth)acrylates. These (meth)acrylates can be used singly or in combination of two or more. Further, among these (meth)acrylates, one or more selected from the group consisting of t-butyl (meth)acrylate and benzyl (meth)acrylate is preferable from the viewpoint of facilitating the conversion reaction to a carboxyl group, and industrial t-butyl (meth)acrylate is more preferable from the viewpoint of easy availability.

In general formula (c1), B represents an aromatic group or an alkyl group. As the alkyl group, an alkyl group having 1 to 10 carbon atoms can be used. Further, n represents an integer of 1-5.

In the living anionic polymerization method, when an attempt is made to directly polymerize a (meth)acrylate monomer onto the active terminal of a strongly nucleophilic styrenic polymer, polymerization may fail due to nucleophilic attack on the carbonyl carbon. Therefore, when the (meth)acrylate monomer is polymerized in A ¹ -A ² , a reaction modifier can be used to adjust the nucleophilicity, and then the (meth)acrylate monomer can be polymerized. B in general formula (c1) is a group derived from a reaction modifier. Specific examples of reaction modifiers include diphenylethylene, α-methylstyrene, p-methyl-α-methylstyrene and the like.

The living anionic polymerization method can be carried out by a batch system as used in conventional free radical polymerization by adjusting the reaction conditions, or by a continuous polymerization method using a microreactor. Since the microreactor has good miscibility between the polymerization initiator and the monomer, the reactions start at the same time, the temperature is uniform, and the polymerization rate can be uniformed, so that the molecular weight distribution of the produced polymer can be narrowed. At the same time, since the growing ends are stable, it becomes easy to produce a block copolymer in which both block components are not mixed. In addition, since the controllability of the reaction temperature is good, it is easy to suppress side reactions.

A general method of living anionic polymerization using a microreactor is described with reference to FIG. 1, which is a schematic diagram of a microreactor.

First, a first monomer and a polymerization initiator for initiating polymerization are respectively introduced from tube reactors P1 and P2 into a T-shaped micromixer M1 equipped with a flow channel capable of mixing a plurality of liquids. In mixer M1, a first monomer is living anionically polymerized to form a first polymer (Step 1).

Next, the obtained first polymer is transferred to the T-shaped micromixer M2, and the growing terminal of the obtained polymer is trapped by the reaction modifier introduced from the tube reactor P3 in the same mixer M2. to adjust the reaction (step 2). At this time, it is possible to control the number of n in the general formula (c1) depending on the type and amount of the reaction modifier used.

Next, the reaction-controlled first polymer in the T-shaped micromixer M2 is transferred to the T-shaped micromixer M3, and the second monomer introduced from the tube reactor P4 is transferred to the T-shaped micromixer M3. and the first polymer subjected to the reaction control are continuously subjected to living anionic polymerization (step 3).

After that, a block copolymer is produced by quenching the reaction with a compound having an active proton (methanol, etc.).

When the polymer P represented by the general formula (c1) is produced in the microreactor, a monomer having a hydrophobic group (for example, a monomer having an aromatic ring or a heterocyclic ring) is used as the first monomer, By reacting using an organic lithium initiator as a polymerization initiator, ^A2 , a polymer block having a hydrophobic group (for example, a polymer block having a structural unit derived from a monomer having an aromatic or heterocyclic ring) is obtained. ( ^One end of the polymer block ^A2 is bound to an organic group, which is the organolithium initiator residue of A1).

Next, after adjusting the reactivity of the growing terminal using a reaction modifier, a monomer containing a (meth)acrylate having a regeneratable protecting group for the anionic group is reacted as the second monomer to obtain a polymer. get a block

After that, the anionic group is regenerated by a deprotection reaction such as hydrolysis to obtain the A ³ (that is, the polymer block containing the anionic group).

A method for regenerating an anionic group by a deprotection reaction such as hydrolysis of an ester bond of a protective group capable of regenerating the anionic group will be described in detail below.

The hydrolysis reaction of an ester bond proceeds under both acidic and basic conditions, but the conditions differ slightly depending on the group having an ester bond. For example, when the group having an ester bond is a primary alkoxycarbonyl group such as a methoxycarbonyl group, or a secondary alkoxycarbonyl group such as an isopropoxycarbonyl group, hydrolysis is performed under basic conditions. A carboxyl group can be obtained. At this time, examples of the basic compound used under basic conditions include metal hydroxides such as sodium hydroxide and potassium hydroxide.

When the group having an ester bond is a tertiary alkoxycarbonyl group such as a t-butoxycarbonyl group, the carboxyl group can be obtained by hydrolysis under acidic conditions. At this time, examples of the acidic compound used under acidic conditions include mineral acids such as hydrochloric acid, sulfuric acid and phosphoric acid; breasted acids such as trifluoroacetic acid; and Lewis acids such as trimethylsilyl triflate. The reaction conditions for hydrolysis of a t-butoxycarbonyl group under acidic conditions are disclosed, for example, in “The Chemical Society of Japan, 5th Edition, Experimental Chemistry Course 16, Synthesis of Organic Compounds IV”.

As a method for converting a t-butoxycarbonyl group to a carboxyl group, for example, a method using a cation exchange resin in place of the above acid can be mentioned. Examples of cation exchange resins include resins having acid groups such as carboxyl groups (--COOH) and sulfo groups (--SO ₃ H) in side chains of polymer chains. Among these, a cation exchange resin having a sulfo group in the side chain of the resin and exhibiting strong acidity is preferable because the progress of the reaction can be accelerated. Commercially available cation exchange resins include strongly acidic cation exchange resin "Amberlite" manufactured by Organo Corporation. From the viewpoint of effective hydrolysis, the amount of the cation exchange resin used is preferably 5 to 200 parts by mass, more preferably 10 to 100 parts by mass, relative to 100 parts by mass of the polymer represented by the general formula (c1). preferable.

When the group having an ester bond is a phenylalkoxycarbonyl group such as a benzyloxycarbonyl group, it can be converted to a carboxyl group by hydrogenation reduction reaction. At this time, as the reaction conditions, the phenylalkoxycarbonyl group can be quantitatively regenerated to the carboxyl group by reacting with hydrogen gas as a reducing agent at room temperature in the presence of a palladium catalyst such as palladium acetate.

As described above ^, the reaction conditions for conversion to a carboxyl group differ depending on the type of group having an ester bond. A polymer obtained by copolymerization using will have a t-butoxycarbonyl group and an n-butoxycarbonyl group. Here, since the n-butoxycarbonyl group does not hydrolyze under acidic conditions where the t-butoxycarbonyl group hydrolyzes, it is possible to selectively hydrolyze only the t-butoxycarbonyl group to deprotect the carboxyl group. becomes. Therefore, it is possible to adjust the acid value of the hydrophilic block (A ³ ) by appropriately selecting a monomer containing a (meth)acrylate having a regeneratable protecting group for the anionic group, which is a raw material monomer for A ³ .

From the viewpoint of improving the stability of the aqueous pigment dispersion in which the pigment is dispersed in water by the polymer P, in the polymer P represented by the general formula (c1), the polymer block (A ² ) and the polymer block (A ³ ) It is more advantageous to be a block copolymer in which the polymer blocks are grouped together with a certain length and regularly bonded, rather than a random copolymer in which the is randomly arranged and bonded. The aqueous pigment dispersion is a raw material used in the production of ink, and is a liquid in which the polymer P is used to disperse a pigment in water at a high concentration. The molar ratio A ² : A ³ of the polymer block (A ² ) and the polymer block (A ³ ) is, for example, from the viewpoint of easily maintaining good ejection stability required when ejecting ink in an inkjet recording method, and from the viewpoint of color development. 100:10 to 100:500 is preferable, and 100:10 to 100:450 is more preferable, from the viewpoint of easily obtaining an ink capable of producing a printed matter having even better properties.

In the polymer P represented by the general formula (c1), the number of aromatic ring- or heterocyclic ring-containing monomers that give the polymer block (A ² ) is preferably 5 to 40, more preferably 6 to 30, and 7 to 25. More preferred. The number of anionic groups constituting the polymer block (A ³ ) is preferably 3-20, more preferably 4-17, even more preferably 5-15.

The molar ratio A ² : A ³ of the polymer block (A ² ) and the polymer block (A ³ ) is the number of moles of the aromatic ring or heterocyclic ring constituting the polymer block (A ² ) and the polymer block (A ³ ). It is preferably 100:7.5 to 100:400 when represented by the molar ratio with the number of moles of the anionic group.

The acid value of the polymer P represented by the general formula (c1) is, for example, from the viewpoint of easily maintaining good ejection stability required when ejecting ink in an inkjet recording method, and from the point of scratch resistance and the like. From the viewpoint of easily obtaining an ink capable of producing even better printed matter, it is preferably 40 to 400 mgKOH/g, more preferably 40 to 300 mgKOH/g, even more preferably 40 to 190 mgKOH/g. The acid value of the polymer P was determined by the same acid value measurement method as the measurement method of the fine particles of the polymer P.

In the ink according to this embodiment, the anionic groups of the polymer P are preferably neutralized.

As the basic compound that neutralizes the anionic groups of the polymer P, any known and commonly used basic compound can be used. For example, inorganic basic substances such as alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, Organic basic compounds such as ammonia, triethylamine and alkanolamine can be used.

The neutralized amount of polymer P present in the aqueous pigment dispersion need not be 100% neutralized relative to the acid value of the polymer. Specifically, the neutralization rate of the polymer P is preferably 20 to 200%, more preferably 80 to 150%.

The ink according to the present embodiment preferably contains a binder resin from the viewpoint of easily obtaining printed matter having excellent scratch resistance. Examples of binder resins include polyvinyl alcohol, gelatin, polyethylene oxide, polyvinylpyrrolidone, acrylic resin, urethane resin, dextran, dextrin, carrageenan (κ, ι, λ, etc.), agar, pullulan, water-soluble polyvinyl butyral, hydroxyl Ethyl cellulose, carboxymethyl cellulose, etc. can be used singly or in combination. Among them, as the binder resin, it is preferable to use an acrylic resin, and it is more preferable to use an acrylic resin having an amide group.

Ink containing a binder resin has the property that even if the ink at the ink ejection port solidifies due to solvent evaporation due to drying, the solidified matter can be easily dispersed in the ink by recirculating the ink through the ejection port. Excellent (redispersibility). As a result, when ejecting from the inkjet head, even if the ejection is restarted after being interrupted for a certain period of time, it is less likely that the ejected droplets will be bent or the ejection port will be clogged. can be effectively prevented.

As the acrylic resin having an amide group, a polymer of an acrylic monomer having an amide group and other monomers used as necessary can be used.

Examples of acrylic monomers having an amide group include (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, and N-methylol(meth)acrylamide. , N-isopropyl (meth)acrylamide, N-butyl (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N,N-dipropyl (meth)acrylamide, N,N -Dimethylaminopropyl (meth)acrylamide, diacetone (meth)acrylamide, hydroxyethyl (meth)acrylamide, acrylamide, N,N-dimethyl (meth)acrylamide and the like can be used.

Other monomers that can be used in the production of the acrylic resin include, for example, (meth)acrylic acid and alkali metal salts thereof; methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2 - Ethylhexyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate and other (meth) acrylate monomers; (meth) acrylonitrile, 2-dimethylaminoethyl (meth) acrylate, glycidyl ( Acrylic monomers such as meth)acrylates; aromatic vinyl compounds (styrene, α-methylstyrene, p-tert-butylstyrene, vinylnaphthalene, vinylanthracene, etc.), vinylsulfonic acid compounds (vinylsulfonic acid, styrenesulfonic acid etc.), vinylpyridine compounds (2-vinylpyridine, 4-vinylpyridine, naphthylvinylpyridine, etc.), vinyltriethoxysilane, vinyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3 -methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, and the like can be used.

As the other monomer, a monomer having an aromatic group, such as styrene and benzyl (meth)acrylate, is preferable from the viewpoint of further improving the affinity with the pigment.

The amide group-containing acrylic resin imparts the effect of improving the redispersibility to the ink and has excellent dispersion stability in an aqueous medium. In the acrylic resin having an amide group, the amount of the acrylic monomer having an amide group used is determined from the viewpoint of further improving the redispersibility of the ink and the dispersion stability of the ink component in an aqueous medium. It is preferably 0.5 to 5% by mass, more preferably 0.5 to 4% by mass, and even more preferably 1.5 to 3% by mass, based on the total amount of monomers used to produce the system resin.

The acrylic resin may contain a component that is insoluble in tetrahydrofuran (THF), which is a developing solvent for molecular weight measurement by gel permeation chromatography, and whose molecular weight is difficult to measure. From the viewpoint of further improving the adhesion of ink to plastics and metals that do not easily absorb solvents such as water, or highly hydrophobic coated paper and art paper, the content of THF-insoluble components at 25 ° C. is 20 mass. %, more preferably less than 5% by mass, and still more preferably no THF-insoluble components.

The number average molecular weight of the acrylic resin (eg, acrylic resin soluble in THF) is preferably 10,000 to 100,000, more preferably 20,000 to 100,000. The acrylic resin preferably has a weight average molecular weight of 30,000 to 1,000,000, more preferably 50,000 to 1,000,000.

Polyolefins, for example, can also be used as the binder resin.

As the polyolefin, a homopolymer or copolymer of a monomer containing an olefinic monomer as a main component can be used. Examples of olefinic monomers that can be used include α-olefins such as ethylene, propylene, butene, hexene, methylbutene, methylpentene and methylhexene; and cyclic olefins such as norbornene.

Oxidized polyolefins can also be used as polyolefins. As the oxidized polyolefin, for example, a polyolefin in which oxygen atoms are introduced into the molecule by thermal decomposition, chemical decomposition using an acid or alkaline component, or the like can be used. The oxygen atom constitutes, for example, a polar carboxyl group.

The melting point of the polyolefin is preferably from 90 to 200°C, more preferably from 120°C to less than 160°C. In these cases, even when the printed matter is superimposed immediately after printing, it is possible to impart good settability such that the ink on the surface of the recording medium does not peel off and excellent abrasion resistance. The melting point of polyolefin refers to the value measured by a melting point measuring apparatus conforming to JIS K 0064.

The polyolefin preferably exists in a state dissolved or dispersed in a solvent such as an aqueous medium, and more preferably in an emulsion state dispersed in a solvent such as an aqueous medium.

In that case, the average particle diameter of the polyolefin particles formed by the polyolefin is, for example, 10 from the viewpoint of easily achieving both good ink ejection stability and good settability after printing when printing by an inkjet recording method. ~200 nm is preferable, and 30 to 150 nm is more preferable. The average particle size of the polyolefin (A) is a value measured by a dynamic light scattering method using a Microtrac UPA particle size distribution meter manufactured by Nikkiso Co., Ltd.

The binder resin is used in an amount of 2 to 7% by mass based on the total amount of the ink from the viewpoint of easily preventing the occurrence of the streaks, and from the viewpoint of improving the print density and scratch resistance of the printed matter and imparting good gloss. Preferably, 2 to 5% by mass is more preferable. In addition, the ink containing the binder resin within these ranges can further improve the scratch resistance of the printed matter by cross-linking the binder resin through a heating process after printing to form a strong film. In addition, even when water is dropped on the printed material or rubbed with a cloth containing water, the ink on the surface of the recording medium is not peeled off, so that good water resistance can be imparted.

From the viewpoint of obtaining excellent ejection stability, the total amount of the pigment and resin component is more than 0% by mass and 13% by mass or less with respect to the total amount of the ink. From the viewpoint of easily obtaining excellent ejection stability, the total amount of the pigment and the resin component is preferably 11% by mass or less, more preferably 10.5% by mass or less, and further preferably 10% by mass or less, relative to the total amount of the ink. Preferably, 9.5% by weight or less is particularly preferred, and 9% by weight or less is extremely preferred. The total amount of the pigment and the resin component should be the total amount of the ink from the viewpoints of ensuring the print density, easily ensuring the adhesion of the ink on the recording medium, and easily ensuring the dispersion stability of the pigment. On the other hand, 1% by mass or more is preferable, 5% by mass or more is more preferable, 6% by mass or more is still more preferable, and 7% by mass or more is particularly preferable.

The ink according to this embodiment can contain an aqueous medium. The ink according to this embodiment may be an aqueous ink containing an aqueous medium. By the way, due to the improvement of inkjet technology, the inkjet recording method is expected to be used in digital printing output machines in industrial applications, and non-absorbent or difficult-to-absorb substrates such as solvent inks and UV inks (for example, PVC ( Printers capable of printing on plastic substrates such as polyvinyl chloride) and PET (polyethylene terephthalate) are commercially available. In recent years, however, the demand for water-based inks containing water-based media has increased from the viewpoint of environmental considerations and the like. In recent years, the expansion of the application of inkjet recording method is expected, such as non-absorbent substrates such as coated paper (coated paper), cardboard, non-absorbent substrates such as those used for outdoor advertisements, etc. There is a growing need for printing with water-based inks. Water-based inks tend to be repelled on these substrates, and conventionally, portions of the substrate to which the ink is originally applied tend to be exposed on the surface (streak-like printing defects tend to occur). On the other hand, according to the present embodiment, even if the ink contains an aqueous medium, it is possible to suppress the occurrence of streak-like printing defects.

As the aqueous medium, water alone or a mixed solvent of water and an organic solvent can be used. As water, specifically, pure water or ultrapure water such as ion-exchanged water, ultrafiltrated water, reverse osmosis water, and distilled water can be used.

The content of the aqueous medium is, with respect to the total amount of ink, from the viewpoint that it is easy to obtain an ink that has excellent setting properties, has high ejection stability required when ejecting by an inkjet recording method, and can produce clear printed matter. 1 to 60% by mass is preferable, 5 to 50% by mass is more preferable, 10 to 45% by mass is still more preferable, and 20 to 40% by mass is particularly preferable.

Constituents of the ink according to the present embodiment include coloring materials (excluding pigments), compound (E) having a urea bond (hereinafter sometimes referred to as "compound (E)"), organic solvent, surfactant, and others. can be used. The ink according to the present embodiment preferably contains the compound (E) from the viewpoint of improving the settability of the printed matter. The ink according to the present embodiment preferably contains a binder resin and the compound (E) from the viewpoint of being able to impart good settability to printed matter and excellent scratch resistance. In the ink according to this embodiment, the coloring material, binder resin, compound (E), etc. are preferably dissolved or dispersed in an aqueous medium as a solvent.

The ink according to this embodiment may contain a coloring material other than the pigment. As the coloring material, known and commonly used dyes and the like can be used.

The total amount of the pigment and colorant is from the viewpoint of easily preventing the occurrence of streaks, maintaining excellent dispersion stability of the pigment and colorant, and easily improving the print density and abrasion resistance of the printed matter. , with respect to the total amount of the ink, preferably 0.5 to 20% by mass, more preferably more than 0.5% by mass and 20% by mass or less, still more preferably 1 to 20% by mass, and 1.5 to 15% by mass Particularly preferred, 2-10% by weight is very preferred, 3-8% by weight is very preferred, and 3-6% by weight is even more preferred.

The ink according to this embodiment preferably contains the compound (E). As the compound (E), one or more selected from the group consisting of urea and urea derivatives can be used. Since urea and urea derivatives have a high moisturizing function and function as a wetting agent, they prevent drying and solidification of the ink at the ink ejection port of the inkjet head, and easily ensure excellent ejection stability. As a result, even if the shortest distance between the ink ejection port of the inkjet head and the recording medium is 2 mm or more, the occurrence of streaks in printed matter can be easily reduced. In addition, since urea and urea derivatives are likely to release water when heated, from the viewpoint of obtaining printed matter with even better setting properties, when using urea or urea derivatives, non-absorbent or difficult-to-absorb absorbents are preferred. Heat drying is preferably performed after printing the ink on the recording medium.

Urea derivatives include ethylene urea, propylene urea, diethyl urea, thiourea, N,N-dimethyl urea, hydroxyethyl urea, hydroxybutyl urea, ethylenethiourea, diethylthiourea and the like, and these may be used alone or in combination of two. Any combination of the above can be used. Among them, the compound (E) is preferably one or more selected from the group consisting of urea, ethylene urea and 2-hydroxyethyl urea, from the viewpoint of obtaining printed matter with even better setting properties.

The content of the compound (E) is 1 to 20% by mass with respect to the total amount of the ink from the viewpoint of the ejection stability required when the ink is ejected by an inkjet recording method and the printed matter with excellent settability. is preferred, 2 to 15 mass % is more preferred, and 3 to 10 mass % is even more preferred.

When the ink contains the binder resin and the compound (E), the mass ratio of the binder resin to the compound (E) [binder resin/compound (E)] is 1/6 from the viewpoint of easily obtaining the effect of improving the settability of the printed matter. ~6/1 is preferred, 1/6 to 3/1 is more preferred, and 1/5 to 1/1 is even more preferred.

The ink according to this embodiment may contain an organic solvent. Examples of organic solvents include ketones such as acetone, methyl ethyl ketone, methyl butyl ketone and methyl isobutyl ketone; alcohols such as methanol, ethanol, 2-propanol, 2-methyl-1-propanol, 1-butanol and 2-methoxyethanol; Ethers such as tetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane; dimethylformamide, N-methylpyrrolidone, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol Glycols; Diols such as butanediol, pentanediol, hexanediol, diols of the same family; Glycol esters such as propylene glycol laurate; Diethylene glycol monoethyl, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol ether, dipropylene Glycol ethers and glycol ethers such as cellosolve including triethylene glycol ether; butyl alcohols such as methanol, ethanol, isopropyl alcohol, 1-propanol, 2-propanol, 1-butanol and 2-butanol, pentyl alcohol, and these alcohols such as homologous alcohols; sulfolane; lactones such as γ-butyrolactone; lactams such as N-(2-hydroxyethyl)pyrrolidone; can be done.

The organic solvent has a boiling point of 100 to 200° C., in addition to those mentioned above, from the viewpoint of easily obtaining a quick-drying effect of quickly drying the discharged liquid droplets on the recording medium after they land on the surface of the recording medium. and a water-soluble organic solvent (f1) having a vapor pressure of 0.5 hPa or more at 20°C.

Water-soluble organic solvents (f1) include 3-methoxy-1-butanol, 3-methyl-3-methoxy-1-butanol, 3-methoxy-3-methyl-1-butyl acetate, ethylene glycol monomethyl ether, and ethylene glycol. Monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, ethylene glycol-t-butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monomethyl ether acetate , diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, 4-methoxy-4-methyl-2-pentanone, ethyl lactate and the like, and these may be used alone or in combination of two or more. can be done.

Among them, the water-soluble organic solvent (f1) is easy to maintain good dispersion stability of the ink and, for example, it is easy to suppress deterioration of the ink ejection nozzle provided in the inkjet device due to the influence of the solvent contained in the ink. From the point of view, it is preferable to use a water-soluble organic solvent whose HSP (Hansen Solubility Parameter) hydrogen bond term _δH is in the range of 6-20.

Specific examples of the water-soluble organic solvent having an HSP hydrogen bond term within the above range include 3-methoxy-1-butanol, 3-methyl-3-methoxy-1-butanol, ethylene glycol monomethyl ether, and ethylene glycol monoethyl ether. , ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, ethylene glycol-t-butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monopropyl ether 1 selected from the group consisting of More than one species is preferred, and one or more selected from the group consisting of 3-methoxy-1-butanol and 3-methyl-3-methoxy-1-butanol is more preferred.

Organic solvents that can be used in combination with aqueous media include water-soluble organic solvents ( In addition to f1) or together with the water-soluble organic solvent (f1), propylene glycol (f2) and one or more organic solvents (f3) selected from the group consisting of glycerin, glycerin derivatives, diglycerin and diglycerin derivatives is preferably used in combination with

As the organic solvent (f3), for example, glycerin, diglycerin, polyglycerin, diglycerin fatty acid ester, polyoxypropylene (n) polyglyceryl ether represented by the following general formula (f1), represented by the following general formula (f2) Polyoxyethylene (n) polyglyceryl ether and the like can be used singly or in combination of two or more. Among them, the organic solvent (f3) is excellent in settability of the printed matter, and from the viewpoint that it is easy to obtain the effect of preventing drying and solidification of the ink at the ink ejection port, glycerin and polyoxypropylene (n = 8 to 15) (n ) one or more selected from the group consisting of polyglyceryl ethers.

m1, m2, n1, n2, p1, p2, q1 and q2 in general formula (f1) and general formula (f2) each independently represents an integer of 1 to 10.

The mass ratio of the water-soluble organic solvent (f1) to the propylene glycol (f2) [water-soluble organic solvent (f1)/propylene glycol (f2)] is excellent in settability of printed matter and prevents drying and solidification of ink at the ink ejection port. From the viewpoint of easily obtaining the effect of preventing, 1/25 to 2/1 is preferable, 1/25 to 1/1 is more preferable, and 1/20 to 1/1 is even more preferable.

The mass ratio of the propylene glycol (f2) to the organic solvent (f3) [propylene glycol (f2)/organic solvent (f3)] is excellent in settability of the printed matter and has the effect of preventing drying and solidification of the ink at the ink ejection port. From the viewpoint of easy availability, 1/4 to 8/1 is preferred, 1/3 to 6/1 is more preferred, and 1/2 to 5/1 is even more preferred.

The content of the organic solvent is preferably 1 to 30% by mass, preferably 5 to 25% by mass, based on the total amount of the ink, from the viewpoint of excellent settability of the printed matter and easy to obtain the effect of preventing drying and solidification of the ink at the ink ejection port. % by mass is more preferred.

The total amount of the aqueous medium and the organic solvent is preferably 20% by mass or more, preferably 30% by mass or more, based on the total amount of the ink, from the viewpoint of easily adjusting the viscosity of the ink to 5 mPas or less and further preventing the ink from drying. More preferably, 40% by mass or more is even more preferable, 50% by mass or more is particularly preferable, and 60% by mass or more is extremely preferable. The total amount of the aqueous medium and the organic solvent may be 90% by mass or less, 80% by mass or less, 70% by mass or less, or 65% by mass or less with respect to the total amount of the ink. you can

The ink according to this embodiment may contain a surfactant. By using a surfactant, after the ink ejected from the ejection port of the inkjet head lands on the recording medium, it easily spreads well on the surface of the recording medium. Furthermore, by using a surfactant, it is possible to improve the leveling property of the ink by lowering the surface tension of the ink.

As surfactants, various anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc. can be used, and the occurrence of streak-like printing defects can be suppressed. From the viewpoint of ease of use, one or more selected from the group consisting of anionic surfactants and nonionic surfactants is preferable.

Examples of anionic surfactants include alkylbenzenesulfonates, alkylphenylsulfonates, alkylnaphthalenesulfonates, higher fatty acid salts, sulfuric acid ester salts of higher fatty acid esters, sulfonates of higher fatty acid esters, and sulfuric acid of higher alcohol ethers. ester salts and sulfonates, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, etc.; Specific examples include dodecylbenzenesulfonate, isopropylnaphthalenesulfonate, monobutylphenylphenolmonosulfonate, monobutylbiphenylsulfonate, and dibutylphenylphenoldisulfonate.

Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, poly Oxyethylene glycerin fatty acid ester, polyglycerin fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, fatty acid alkylolamide, alkylalkanolamide, acetylene glycol, oxyethylene adduct of acetylene glycol, polyethylene glycol and polypropylene glycol block copolymers, among which polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester. , polyoxyethylene sorbitan fatty acid ester, fatty acid alkylolamide, acetylene glycol, oxyethylene adduct of acetylene glycol, and polyethylene glycol polypropylene glycol block copolymer.

The ink according to the present embodiment preferably contains an acetylenic surfactant from the viewpoint of easily suppressing the occurrence of streak-like printing defects. Acetylene-based surfactants are surfactants having an acetylene structure in the molecule. The acetylene-based surfactant preferably contains one or more selected from the group consisting of acetylene glycol and oxyethylene adducts of acetylene glycol, from the viewpoint of easily suppressing the occurrence of streak-like printing defects.

Other surfactants include silicone-based surfactants such as polysiloxane oxyethylene adducts; fluorine-based surfactants such as perfluoroalkylcarboxylates, perfluoroalkylsulfonates, and oxyethylene perfluoroalkyl ethers; Biosurfactants such as spiculisporic acid, rhamnolipids, lysolecithin and the like can also be used.

The content of the acetylenic surfactant is preferably 80 to 100% by mass, more preferably 85 to 100% by mass, based on the total amount of the surfactant, from the viewpoint of easily suppressing the occurrence of streak-like printing defects. Preferably, 90 to 100% by mass is more preferable, and 95 to 100% by mass is particularly preferable.

The number of carbon atoms in the main chain of the acetylenic surfactant is preferably 20 or less, more preferably 18 or less, still more preferably 15 or less, and particularly preferably 12 or less, from the viewpoint of easily suppressing the occurrence of streak-like printing defects. . The number of carbon atoms in the main chain of the acetylenic surfactant is preferably 5 or more, more preferably 8 or more, and still more preferably 10 or more from the viewpoint of easily suppressing the occurrence of streak-like printing defects. From these points of view, the number of carbon atoms in the main chain of the acetylenic surfactant is preferably 5-20, more preferably 8-15, even more preferably 10-12. The number of carbon atoms in the main chain of the acetylenic surfactant may be 12 or more, or may be 12-20. The number of carbon atoms in the main chain is the number of carbon atoms in the longest molecular chain (eg, carbon chain) containing acetylene bonds.

The HLB value of the surfactant is from the viewpoint of easily suppressing the occurrence of streak-like printing defects, and from the viewpoint of easily maintaining the state in which the surfactant is dissolved in the ink containing water as the main solvent. 1 to 13 are preferred, 1 to 12 are more preferred, 1 to 10 are more preferred, 2 to 9 are particularly preferred, 3 to 8 are very preferred, 4 to 8 are very preferred, 4 to 7 are even more preferred, 4 to 6 are more preferred. The HLB value of the acetylenic surfactant is a viewpoint that it is easy to suppress the occurrence of streak-like printing defects, and a viewpoint that it is easy to stably maintain the state in which the surfactant is dissolved in the ink containing water as the main solvent. Therefore, these ranges are preferred. The HLB value of a surfactant can be determined, for example, by Griffin's method.

The surfactant content is preferably 0.001 to 5% by mass, more preferably 0.001 to 3% by mass, still more preferably 0.001 to 2% by mass, and 0.001% by mass, based on the total amount of the ink. -1.5% by weight is particularly preferred, 0.01 to 1.5% by weight is very preferred, 0.1 to 1.5% by weight is very preferred, and 0.5 to 1.5% by weight is even more preferred. , more preferably 0.8 to 1.5% by mass, particularly preferably 1 to 1.5% by mass. Ink containing a surfactant at these contents has good wettability of ejected droplets on the surface of the recording medium, and tends to have sufficient wetting and spreading on the recording medium. It is easy to obtain the effect of preventing Furthermore, the ink containing the surfactant within each of the above ranges is likely to have the effect of improving the leveling properties of the coating film. From the same point of view, it is preferable that the content of the acetylenic surfactant is within the ranges described above.

The ink according to the present embodiment includes a wetting agent (drying inhibitor), a penetrant, a preservative (for example, ACTICIDE B-20 manufactured by So Japan Co., Ltd.), a viscosity adjuster, a pH adjuster, a chelating agent, and a plasticizer. Other additives such as agents, antioxidants, UV absorbers, etc. can be included.

A humectant can be used for the purpose of preventing drying of the ink in the ink ejection nozzles of the inkjet head. The content of the humectant is preferably 3 to 50% by mass with respect to the total amount of ink.

The wetting agent is preferably one that is miscible with water and has an effect of preventing clogging of the ejection port of the inkjet head. Examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol having a molecular weight of 2000 or less, and dipropylene glycol. , tripropylene glycol, isopropylene glycol, isobutylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, mesoerythritol, pentaerythritol and the like.

Penetrants include lower alcohols such as ethanol and isopropyl alcohol; ethylene oxide adducts of alkyl alcohols such as ethylene glycol hexyl ether and diethylene glycol butyl ether; and propylene oxide adducts of alkyl alcohols such as propylene glycol propyl ether. The content of the penetrant is preferably 3% by mass or less, more preferably 1% by mass or less, and still more preferably substantially no penetrant, relative to the total amount of the ink.

(Ink manufacturing method)
The ink according to the present embodiment can be produced, for example, by mixing a pigment, a resin component, and an aqueous medium. It can be produced by mixing (E), an organic solvent, a surfactant and the like.

For the mixing, a dispersing machine such as a bead mill, an ultrasonic homogenizer, a high-pressure homogenizer, a paint shaker, a ball mill, a roll mill, a sand mill, a sand grinder, a Dyno mill, a Dispermat, an SC mill, and a nanomizer can be used.

The ink according to the present embodiment may be produced by mixing each component together or sequentially and then stirring the mixture. From the viewpoint of removing impurities mixed in the ink, the obtained ink is preferably subjected to a centrifugal separation treatment or a filtration treatment as necessary.

(recording medium)
The ink according to the present embodiment may be a recording medium having excellent ink absorption such as copy paper (PPC paper) generally used in copiers, a recording medium having an ink absorption layer, or a recording medium having an ink absorption layer. It is possible to print on a non-absorbent recording medium that has no water absorption property at all, or a non-absorbent recording medium with low ink absorption. In particular, the ink according to the present embodiment suppresses the occurrence of streak-like printing defects even when printed on a recording medium that is non-absorbent or difficult to absorb ink, and has excellent settability and durability. It is possible to obtain a printed matter excellent in abrasion resistance and water resistance.

Specific examples of the recording medium that can be used include plain paper, cloth, corrugated board, wood, inkjet paper, art paper, coated paper, lightly coated paper, and plastic film. As the corrugated board, corrugated board having a layer with a water absorption of 10 g/m ² or less may be used. As the coated paper, lightweight coated paper may be used.

From the viewpoint of obtaining a printed matter with even more excellent abrasion resistance and water resistance, the hard-to-absorb recording medium is the following: It is preferable to use a recording medium having a water absorption of 10 g/m ² or less in combination with the ink according to the present embodiment.

The amount of water absorption was measured using an automatic scanning liquid absorption meter (KM500win, manufactured by Kumagai Riki Kogyo Co., Ltd.) under the conditions of 23° C. and 50% relative humidity, and the amount of transfer at a contact time of 100 msec with pure water. It can be measured and taken as the water absorption for 100 msec. Measurement conditions are shown below.

[Spiral Method]
Contact Time: 0.010 to 1.0 (sec)
Pitch: 7 (mm)
Lencth per sampling: 86.29 (degree)
Start Radius: 20 (mm)
End Radius: 60 (mm)
Min Contact Time: 10 (msec)
Max Contact Time: 1000 (msec)
Sampling pattern: 50
Number of sampling points: 19
[Square Head]
Slit span: 1 (mm)
Width: 5 (mm)

Examples of recording media that absorb ink include plain paper, cloth, cardboard, and wood. Further, examples of the recording medium having the absorption layer include ink-jet paper and the like, and specific examples thereof include Pictorico Pro Photo Paper manufactured by Pictorico Co., Ltd. and the like.

Non-absorbent recording media with low ink absorbency include corrugated board, art paper such as printing paper, coated paper (e.g. lightweight coated paper), Lightly coated paper or the like can be used. These non-absorbent recording media are made by applying a coating material to the surface of fine paper, neutral paper, etc., which is mainly composed of cellulose and is generally not surface-treated, to provide a coating layer. Lightly coated paper such as "OK Everlight Coat" manufactured by the company and "Aurora S" manufactured by Nippon Paper Industries Co., Ltd.; "OK Coat L" manufactured by Oji Paper Co., Ltd. and "Aurora L" manufactured by Nippon Paper Industries Co., Ltd. Light weight coated paper (A3) of Oji Paper Co., Ltd. “OK Topcoat + (basis weight 104.7 g / m ² , water absorption at contact time 100 msec (the following water absorption is the same) 4.9 g / m ² ) "Aurora ^Coat " manufactured by Nippon Paper Industries Co., ^{Ltd .;} , water absorption 4.4 g/m ² ) coated paper (A2, B2); art paper (A1) such as "OK Kinto +" manufactured by Oji Paper Co., Ltd. and "Tokubishi Art" manufactured by Mitsubishi Paper Mills It is possible to use a plastic film such as

Examples of the plastic film include polyester films made of polyethylene terephthalate, polyethylene naphthalate, etc.; polyolefin films made of polyethylene, polypropylene, etc.; polyamide films made of nylon, etc.; polystyrene films; polyvinyl alcohol films; polyvinyl chloride films; polyacrylonitrile film; polylactic acid film; As the plastic film, a polyester film, a polyolefin film, or a polyamide film is preferably used, and a polyethylene terephthalate film, a polypropylene film, or a nylon film is more preferably used.

As the plastic film, a film coated with polyvinylidene chloride or the like for imparting barrier properties; a metal layer such as aluminum; good.

The plastic film may be an unstretched film, or may be uniaxially or biaxially stretched. The surface of the film may be untreated, but preferably subjected to various treatments for improving adhesiveness, such as corona discharge treatment, ozone treatment, low-temperature plasma treatment, flame treatment and glow discharge treatment.

The film thickness of the plastic film is appropriately changed depending on the application. It is preferably 100 μm, more preferably 10 to 30 μm. Specific examples thereof include Pyrene and Espet (both registered trademarks) manufactured by Toyobo Co., Ltd.

Among the recording media, the ink according to the present embodiment is corrugated cardboard composed of paperboard that easily absorbs the solvent contained in the ink; It can be suitably used for printing on corrugated cardboard, plastic film, fabric, and the like.

As the corrugated board, for example, a corrugated corrugated core with a liner attached to one or both sides thereof can be used, and single-faced corrugated board, double-faced corrugated board, double-faced corrugated board, double-faced corrugated board, etc. can be used. be able to.

Specifically, the ink according to the present embodiment is corrugated cardboard made of paperboard that easily absorbs the solvent contained in the ink; It can be suitably used for printing on corrugated cardboard or the like. The ink according to the present embodiment can be used when a non-absorbent or non-absorbent recording medium such as corrugated cardboard is provided with a colored layer that does not easily absorb the solvent in the ink, a waterproof layer, etc. on the surface of the paperboard. Even if there is, the landed ink tends to wet and spread on the surface of the recording medium, and as a result, the occurrence of streaks in printed matter can be effectively suppressed.

Further, when inkjet printing is performed on cardboard with the ink according to the present embodiment, from the surface (x) having the ink ejection port to the position (y) where the perpendicular line of the surface (x) intersects the recording medium Even if the distance is 2 mm or more, the droplets spread sufficiently after landing on the recording medium, so that streaks on printed matter can be effectively prevented.

Among the corrugated cardboards, the corrugated board provided with a colored layer, a waterproof layer, etc. on the surface is coated with a coloring agent or a waterproofing agent on the surface of the corrugated board made of the above-mentioned paperboard, for example, by a curtain coating method, a roll coating method, or the like. It is possible to use the one on which a coating film is formed.

Examples of the colored layer include those having a whiteness of 70% or more.

Regarding layers such as colored layers and waterproof layers possessed by cardboard, the amount of water absorbed by the recording medium when the recording surface of the recording medium such as cardboard is in contact with water for 100 msec is 10 g/m from the viewpoint of easily obtaining the waterproof effect of the printed matter. m ² or less is preferred.

According to the method for manufacturing a printed matter according to the present embodiment, it is possible to obtain a printed matter that effectively suppresses the occurrence of printing defects such as missing nozzles, twisting, streaks, and the like. Therefore, the printed matter obtained by such a method can be used for, for example, packaging materials such as cardboard; plastic films and packaging materials using the same; and textile products such as T-shirts.

EXAMPLES The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

<Preparation of polymer>
(Polymer (P-1))
A hexane solution of normal butyl lithium (BuLi) and a styrene solution in which styrene is dissolved in tetrahydrofuran in advance are introduced from the tube reactors P1 and P2 shown in FIG. got a union.
Next, the polymer obtained in the above step is transferred to the T-shaped micromixer M2 through the tube reactor R1 shown in FIG. -methylstyrene (α-MeSt)).
Next, a tert-butyl methacrylate solution prepared by dissolving tert-butyl methacrylate in tetrahydrofuran in advance was introduced from the tube reactor P4 shown in FIG. The coalescence and continuous living anionic polymerization reactions were carried out. Thereafter, a block copolymer (PA-1) composition was produced by quenching the living anionic polymerization reaction by supplying methanol. A block copolymer (PA-1) composition was recovered from tube reactor R3.

When producing the block copolymer (PA-1) composition, the reaction temperature was set to 24° C. by immersing the entire microreactor shown in FIG. 1 in a constant temperature bath. The molar ratio of the monomers constituting the block copolymer (PA-1) composition obtained by the above method is (BuLi/styrene/α-methylstyrene/tert-butyl methacrylate) = 1.0/12.0/ 2.0/8.1. The obtained block copolymer (PA-1) composition was hydrolyzed by treatment with a cation exchange resin, then distilled off under reduced pressure, and the resulting solid was pulverized to obtain a powdery polymer ( P-1) was obtained.

The physical properties of the obtained polymer (P-1) were measured as follows.

[Measurement of number average molecular weight (Mn)]
It was measured under the following conditions by a gel permeation chromatography (GPC) method.
Measuring device: high-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were connected in series and used.
"TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 Book "TSKgel G2000" (7.8 mm ID x 30 cm) x 1 Detector: RI (differential refractometer)
Column temperature: 40°C
Eluent: Tetrahydrofuran Flow rate: 1.0 mL/min Injection volume: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4% by mass)
Standard sample: A calibration curve was created using the following standard polystyrene.

{standard polystyrene}
"TSKgel standard polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-550" manufactured by Tosoh Corporation

[Measurement of acid value]
The acid value was measured according to JIS test method K 0070-1992. A 0.5 g sample was dissolved in tetrahydrofuran, and the acid value was determined by titration with a 0.1 M potassium hydroxide alcohol solution using phenolphthalein as an indicator.

[Measurement of solubility in water]
0.5 g of a polymer whose particle size is adjusted to a range of 250 μm to 90 μm using sieves with mesh openings of 250 μm and 90 μm is sealed in a bag processed with a 400 mesh wire mesh, immersed in 50 mL of water, and heated at 25 ° C. for 24 hours. The mixture was left to stir gently for a period of time. After soaking for 24 hours, the polymer-encapsulated 400 mesh wire mesh was dried in a dryer set at 110° C. for 2 hours. The change in mass of the 400-mesh wire mesh enclosing the polymer before and after immersion in water was measured, and the solubility was calculated by the following equation.
Solubility [g / 100 mL] = (polymer-encapsulated 400-mesh wire mesh [g] before immersion - polymer-encapsulated 400-mesh wire mesh [g] after immersion) × 2

[Method for Determining Formation of Fine Particles in Water and Measurement of Volume Average Particle Diameter [nm]]
(1) The acid value of the polymer was determined according to the acid value measurement method described above.
(2) After adding 1 g of polymer to 50 mL of water, add 0.1 mol/L potassium hydroxide aqueous solution to neutralize the acid value of the polymer obtained in the above (1) by 100%, and 100% neutralization. did.
(3) Irradiate the 100% neutralized liquid with ultrasonic waves at a temperature of 25 ° C. for 2 hours in an ultrasonic cleaner (Ultrasonic cleaner US-102 manufactured by SND Co., Ltd., 38 kHz self-excited transmission). After being dispersed, it was allowed to stand at room temperature for 24 hours.

A dynamic light scattering particle size distribution measuring device (manufactured by Nikkiso Co., Ltd., dynamic light scattering particle size measuring device " Microtrac particle size distribution meter UPA-ST150") was used to confirm the presence or absence of fine particle formation from the light scattering information of the particles, and if fine particles were present, their volume average particle diameter was measured.

[Measurement of static surface tension]
The static surface tension was measured with a Wilhelmy surface tensiometer using the same sample liquid as the sample liquid obtained in the method for judging fine particle formation in water.

Table 1 shows the raw materials, reaction conditions, and various physical properties of the polymer (P-1) obtained above. In Table 1, BuLi represents normal butyl lithium, St represents styrene, α-MeSt represents α-methylstyrene, and tBMA represents tert-butyl methacrylate.

(Polymer (P-2))
A styrene-acrylic acid resin X-1 (manufactured by Seiko PMC Co., Ltd.) was prepared as the polymer (P-2).

<Preparation of aqueous pigment dispersion>
(Production example 1)
Pigment Black 7 (pigment) 150 parts by mass, polymer (P-1) (pigment dispersant) 45 parts by mass, triethylene glycol (organic solvent) 135 parts by mass, and 20 parts by mass of a 34% by mass potassium hydroxide aqueous solution, It was charged into a 1.0 L intensive mixer (Japan Eirich Co., Ltd.) and kneaded for 25 minutes at a rotor peripheral speed of 2.94 m/sec and a pan peripheral speed of 1 m/sec.
Next, while continuing to stir, 300 parts by mass of ion-exchanged water (first ion-exchanged water) is gradually added to the kneaded material in the intensive mixer container, and then ion-exchanged water (second ion-exchanged water) is added. ) was further added and mixed to obtain an aqueous pigment dispersion K-1 having a pigment concentration of 20% by mass and a resin component concentration (solid concentration) of 6.0% by mass.

(Production Examples 2-4)
An aqueous pigment dispersion was obtained in the same manner as in Production Example 1, except that the raw materials and blending ratios were changed to the raw materials and blending ratios shown in Table 2.

(Production example 5)
Pigment Black 7 (pigment) 100 parts by mass and polymer (P-1) (pigment dispersant) 40 parts by mass were placed in an intensive mixer (manufactured by Eirich Japan Co., Ltd.), and the rotor peripheral speed was 2.9 m / s and the pan peripheral speed was 1 m. /s. Next, 50 parts by mass of propylene glycol (organic solvent, manufactured by Asahi Glass Co., Ltd.) and 13 parts by mass of 34% by mass potassium hydroxide aqueous solution are added to the intensive mixer, and the rotor peripheral speed and pan peripheral speed are the same as above. and kneaded for 2 hours.
Next, while continuing to stir, 200 parts by mass of ion-exchanged water (first ion-exchanged water) is gradually added to the kneaded material in the intensive mixer container, and then ion-exchanged water (second ion-exchanged water) is added. ) was further added and mixed to obtain an aqueous pigment dispersion (K-2) having a pigment concentration of 20% by mass and a resin component concentration (solid concentration) of 8.0% by mass.

(Production Examples 6 to 10)
An aqueous pigment dispersion was obtained in the same manner as in Production Example 5, except that the raw materials and blending ratios were changed to the raw materials and blending ratios shown in Table 2.

PB7 in Table 2 stands for Pigment Black 7, PB15:3 stands for Pigment Blue 15:3, PR122 stands for Pigment Red 122, PY74 stands for Pigment Yellow 74, TEG stands for triethylene glycol, PG stands for stands for propylene glycol.

<Synthesis of binder resin>
In a four-necked flask equipped with a stirrer, thermometer, condenser, and nitrogen introduction tube, 16 g of "New Coal 707SF" (manufactured by Nippon Emulsifier Co., Ltd., an anionic emulsifier), "Noigen TDS-200D" (Daiichi Kogyo Seiyaku Co., Ltd., nonionic emulsifier) 6.5 g and deionized water 220 g were charged, the temperature was raised to 80 ° C. under a nitrogen stream, and an aqueous solution in which 0.8 g of ammonium persulfate was dissolved in 16 g of deionized water was added. did. Further, a mixture of 60 g of 2-ethylhexyl acrylate, 100 g of styrene, 27 g of methyl methacrylate, 0.4 g of 3-methacryloxypropyltrimethoxysilane, 3 g of acrylamide, and 6 g of methacrylic acid was added dropwise over 3 hours. After the dropwise addition, the mixture was allowed to react for 2 hours, then cooled to 25°C, neutralized with 1.5 g of 28% by mass ammonia water, and deionized water was added to obtain a glass transition temperature (Tg) of 35°C and an average particle size. An aqueous acrylic resin dispersion (X-1) of 50 nm was obtained. The solid content concentration of the acrylic resin dispersion (X-1) was 39% by mass.

<Preparation of aqueous ink>
(Preparation Example 1)
20.0 parts by mass of the above aqueous pigment dispersion (K-1) (mass of dispersion containing water etc.), 3.0 parts by mass of propylene glycol, 15.0 parts by mass of glycerin, 5.0 parts by mass of triethylene glycol parts, ethylene urea 5.0 parts by mass, triethanolamine (pH adjuster) 0.2 parts by mass, Surfynol 104PG50 (manufactured by Evonik Japan, surfactant) 1.5 parts by mass, ACTICIDE B-20 (So Japan Co., Ltd., antiseptic) 0.1 parts by mass, 14.1 parts by mass of the acrylic resin aqueous dispersion (X-1) described above (solid content 5.5 parts by mass), and ion-exchanged water are added and stirred. to obtain 100 parts by mass of water-based ink (J1).

(Preparation Examples 2-10)
Aqueous inks (J2) to (J10) were obtained in the same manner as in Preparation Example 1 except that the raw materials and blending ratios were changed to those shown in Table 3. In Table 3, "ratio of the total amount of pigment and resin component" is the ratio of the total amount of pigment and resin component to the total amount of ink. It is the ratio of the total amount of ink to the total amount of ink.

Abbreviations in Table 3 are as follows.
PG: Propylene glycol GLY: Glycerin TEG: Triethylene glycol TEA: Triethanolamine Surfynol104PG50 (manufactured by Evonik Japan, main chain carbon number: 10, HLB value: 4, PG50% by mass solution)
Surfynol 420 (manufactured by Evonik Japan, main chain carbon number: 10, HLB value: 4)
B-20: ACTICIDE B-20 (preservative manufactured by So Japan Co., Ltd. Active ingredient 20% by mass)

<Measurement of Viscosity of Aqueous Ink>
Using a cone-plate type (cone-plate type) rotary viscometer corresponding to an E-type viscometer, the viscosity of the water-based ink was measured under the following conditions. Table 4 shows the results.
Measuring device: TVE-25 type viscometer (manufactured by Toki Sangyo Co., Ltd., TVE-25 L)
Calibration standard solution: JS20
Measurement temperature: 32°C
Rotation speed: 10-100rpm
Injection volume: 1200 μL

The static surface tension of the water-based ink was measured under the following conditions using an automatic surface tension meter to which the Wilhelmy method was applied. Table 4 shows the results.
Measuring device: Automatic surface tensiometer (manufactured by Kyowa Interface Science Co., Ltd., CBVP-Z type)
Measurement temperature: 25°C
Probe: Platinum plate

<Evaluation of streaks in printed matter>
Inkjet head KJ4B-1200 (1200 dpi head) manufactured by Kyocera Corporation is filled with each of the above water-based inks, and the water head difference of the ink sub-tank from the head nozzle plate surface is set to +35 cm, and the negative pressure is set to -5.0 kPa. The feed pressure was adjusted. In addition, the shortest distance between the ink ejection port of the inkjet head and the recording medium (from the surface (x) having the ink ejection port of the inkjet head, the perpendicular line assumed to the surface (x) intersects the recording medium The distance (gap) to the position (y) was set to 2 mm or 3 mm. As the recording medium, corrugated cardboard having a thickness of about 2 mm and having a white colored layer (amount of water absorption of the recording medium for a contact time of 100 msec between the recording surface of the recording medium and water: 5 g/m ² ) was used.
The corrugated cardboard is placed on a table (stage) for fixing the corrugated cardboard, and the temperature of the surface (recording surface) on which the ink lands is raised to 25°C by heating from the underside of the stage using a heat roller. It was adjusted. The temperature of the surface of the recording medium was measured using a surface thermometer.
The driving conditions of the head were the standard voltage and standard temperature of the ink jet head, and the droplet size was set to 18 pL, and 100% solid printing was performed to obtain a printed matter (nozzle check pattern). A print was produced using a 1200 dpi head with an interval of 6 cm between the inkjet heads.

The printed matter was read with a scanner, and the percentage of the area where ink was not applied (ratio of streaks) was calculated using image analysis software "ImageJ". The streak ratio indicates the ratio of the area of the area where the water-based ink was not applied to the area of the area where the above-described 100% solid printing was performed. Table 4 shows the results of evaluation based on the following criteria.
A: streak rate of less than 3% in printed matter B: streak rate of printed matter of 3% or more and less than 5% C: streak rate of printed matter of 5% or more and less than 10% D: streak rate of printed matter of 10% or more

<Evaluation of ejection stability>
A nozzle check pattern was printed on the same recording medium as described above under the condition that the shortest distance between the ink ejection port of the inkjet head and the recording medium was 2 mm using the same apparatus as in <Evaluation of streaks in printed matter>. , confirmed that all nozzles are printing normally. The printing was then stopped and left for 30 minutes. Immediately after the standing, a nozzle check pattern was printed in the same manner as above, and the number of streaks on the printed matter was visually confirmed. Table 4 shows the results of evaluation based on the following criteria.
A: No streaks B: With streaks (less than 10 places)
C: streaks (10 or more)

M1, M2, M3... T-shaped micromixer, P1, P2, P3, P4... Tube reactor, R1, R2, R3... Tube reactor.

Claims (3)

A printing step of obtaining a printed matter by printing ink on a recording medium by an inkjet recording method with a resolution of 1000 to 1200 dpi,
In the printing step, the shortest distance between the ink ejection port of the inkjet head and the recording medium is 2 to 3 mm ,
the ink contains a pigment and a resin component,
the total amount of the pigment and the resin component is more than 0% by mass and 13% by mass or less with respect to the total amount of the ink;
A method for producing a printed matter, wherein the ink has a viscosity of 5 mPa·s or less at 32°C. 2. The method for producing a printed matter according to claim 1, wherein the content of said pigment is more than 0.5% by mass and not more than 20% by mass with respect to the total amount of said ink. 3. The method for producing a printed matter according to claim 1, wherein the recording medium is plain paper, fabric, corrugated board, wood, inkjet paper, art paper, coated paper, lightly coated paper, or plastic film.

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