JP2021107527A - Aqueous inkjet ink and ink set - Google Patents

Abstract

To provide a printed matter excellent in durability and processability of printed images.SOLUTION: An aqueous inkjet ink includes (A) a water-dispersible polyether type aliphatic urethane-based resin, (B) a water-dispersible (meth)acrylic resin, (C) an acetylene glycol-based surfactant having an HLB value of 10.0 or less, a coloring material and water.SELECTED DRAWING: None

Description

The present invention relates to water-based inkjet inks and ink sets.

The inkjet recording system is a printing system in which highly fluid liquid ink is ejected from a fine nozzle and adhered to a base material for printing. This system is a relatively inexpensive device, and has the feature of being able to print high-resolution, high-definition images at high speed and with low noise, and has been rapidly becoming widespread recently.
As inks, water-based inks are widely used because high-quality printed matter can be obtained at low cost. The water-based ink is an ink whose drying property is improved by containing water, and also has an advantage of being excellent in environmental friendliness.

In recent years, inkjet recording systems have a function that expresses functions not only by paper media such as plain paper and special paper, but also by woven fabrics in which ink easily bleeds along fibers, non-woven fabrics such as felt, wood materials, and voids in the base material. It is also used for porous materials and the like, and is also used for plastic base materials, synthetic papers, metal base materials, glass base materials, etc., to which ink does not easily penetrate. In order to perform high-quality printing on such various base materials, high durability is required in the case of base materials used for various building materials, furniture, daily necessities, etc., in addition to high image quality. ..

After forming a printed image, there is a method of coating a printed matter with an overcoat layer containing a highly durable resin to impart durability to the printed matter (Patent Document 1).
Further, Patent Document 2 discloses a coated metal plate in which a hue coating film, a printing layer, and a clear coating film are provided on the metal plate, and the clear coating film contains a specific polyester resin.

Base materials used for building materials, furniture, daily necessities, etc. are more expensive than general paper and may have a very large area. Has a great effect on. Therefore, higher ejection reliability than the usual printing method used for paper or the like is required.
A maintenance mechanism is usually installed in the printer to suppress ejection defects in inkjet printing. In particular, ink may gradually adhere to the vicinity of the nozzle of the inkjet head during continuous printing. If the ink stains near the nozzle become noticeable, the ink may not fly straight from the nozzle, or foreign matter may adhere to the ink stains and the foreign matter may enter the head from the nozzle and clog the nozzle. be.

As maintenance, there is a method of wiping off the ink adhering to the nozzle surface, but there is a method of wiping with a cleaning liquid because wiping with a dry member at that time may damage the nozzle plate. Patent Document 3 proposes an inkjet head cleaning solution containing a solvent having a surface tension of less than 35 mN / m and a basic compound as a cleaning solution for an aqueous pigment inkjet printer.

Japanese Unexamined Patent Publication No. 2013-163370 Japanese Unexamined Patent Publication No. 2008-149584 Japanese Unexamined Patent Publication No. 2009-233911

The method of coating the overcoat layer is effective, but if the strength of the ink coating film itself is low and the durability is low, the amount of resin in the overcoat layer becomes very large. As a result, a considerably thick resin film is formed on the base material, so that there is a problem that the original texture of the base material is lost. Further, when a functional base material is used, there is a problem that the function originally possessed by the functional base material is deteriorated due to an excessive overcoat layer.
Further, it is desirable that the ink coating film on the base material has flexibility. In a deformable base material such as a paper medium, a woven fabric, or a non-woven fabric, it is desired that the ink coating film is also deformed according to the deformation of the base material so that the ink coating film does not crack. In addition, there is also an application in which the printed portion is subjected to processing such as bending, and it is also important to ensure the image quality of the processed portion. When the portion to which the overcoat layer is applied is bent, the resin film is cracked due to the large amount of resin, and a so-called whitening phenomenon may be observed.

Further, the water-based ink is expected to be applied to various base materials because it is excellent in environmental friendliness. However, a resin component is blended with the water-based ink, and the resin component in the water-based ink is further formed on the base material in the form of a coating film. The technology needs to appropriately control the dispersibility of the resin in water and the ease of spreading of the resin on the base material, and further improvement is expected.

In the cleaning solution proposed in Cited Document 3, the basic compound may be effective in redissolving or redispersing the acid component-containing resin used in the ink, but it may be rather effective depending on the combination with the resin and the amount used. When mixed with ink, the stability deteriorates, and the vicinity of the nozzle is contaminated with the thickened admixture and the generated foreign matter, and as a result, the ejection reliability such as image uniformity and continuous ejection may be impaired. It is also important to consider the combination of the maintenance liquid with the ink, and it is desired that the cleaning efficiency is good even when the maintenance liquid is mixed with the ink, for example, when the maintenance liquid is dried and concentrated.

One object of the present invention is to provide a water-based inkjet ink capable of forming a printed matter having excellent durability and processability of a printed image.

One aspect of the present invention is a water-dispersible polyether-type aliphatic urethane resin (A), a water-dispersible (meth) acrylic resin (B), and an acetylene glycol-based surfactant having an HLB value of 10.0 or less. A water-based inkjet ink containing (C), a coloring material, and water.
Another aspect of the present invention includes the above-mentioned water-based inkjet ink, an acetylene glycol-based surfactant (C') having an HLB value of 10.0 or less, and glycerin having an HLB value of 30% by mass or more based on the total amount of the maintenance liquid. An ink set containing a maintenance liquid.

According to one embodiment of the present invention, it is possible to provide a water-based inkjet ink capable of forming a printed matter having excellent durability and processability of a printed image.

Hereinafter, the present invention will be described using one embodiment. The illustrations in the following embodiments do not limit the invention.

"Aqueous inkjet ink"
Examples of the water-based inkjet ink according to the embodiment (hereinafter, may be simply referred to as ink or water-based ink) include a water-dispersible polyether-type aliphatic urethane resin (A) and a water-dispersible (meth) acrylic resin. (B), an acetylene glycol-based surfactant (C) having an HLB value of 10.0 or less, a coloring material, and water are contained.
According to one embodiment, it is possible to provide a printed matter having excellent durability and processability of a printed image. Further, according to one embodiment, it is possible to provide a printed matter having excellent image quality of a printed image.
Hereinafter, the water-dispersible polyether type aliphatic urethane resin (A) is also referred to as a urethane resin (A), and the water dispersible (meth) acrylic resin is also referred to as a (meth) acrylic resin (B), and has an HLB value. The acetylene glycol-based surfactant (C) having a value of 10.0 or less is also referred to as a surfactant (C).

The ink according to one embodiment is a combination of a flexible polyether type aliphatic urethane resin (A) and a hard (meth) acrylic resin (B), and has a high wettability. In addition, by using an acetylene glycol-based surfactant (C) having a low HLB value that easily swells the urethane-based resin (A) in the ink, the ink coating film uniformly covers the base material after printing and drying, resulting in durability and durability. It is possible to form an ink coating film having excellent workability. Since the ink coating film is excellent in durability and workability, it is possible to suppress the occurrence of cracks or whitening phenomenon in the processed portion even when processing such as bending is performed after the ink coating film is formed. In addition, the durability of the ink coating film after processing can be improved.
One of the reasons will be explained below, but it is not bound by the following reasons.
According to one embodiment, the ink contains both a flexible polyether type aliphatic urethane resin (A) and a hard (meth) acrylic resin (B), whereby the ink is formed. The durability and workability of the coating film can be improved.
Since the ink contains a low HLB value surfactant (C) having an action of swelling the urethane resin (A) together with the urethane resin (A), the ink coating film dries and forms a film after printing. At that time, the surfactant (C) is concentrated while the moisture volatilizes on the base material, the swelling of the urethane resin (A) progresses, and the film formation becomes easier, forming a stronger ink coating film. The durability of the ink coating film can be improved. Further, since the urethane resin (A) has flexibility, the processability of the ink coating film can be improved. As a surfactant that easily swells the polyether type aliphatic urethane resin (A), an acetylene glycol-based surfactant having an HLB value of 10.0 or less and a low HLB value can be preferably used.

Further, the polyether type aliphatic urethane resin (A) can impart durability and processability to the ink coating film in a well-balanced manner. Further, this urethane-based resin (A) can prevent yellowing and deterioration of the ink coating film and can form an ink coating film having higher image quality.

The ink according to one embodiment can contain a water-dispersible polyether type aliphatic urethane resin (A).
Since the urethane-based resin (A) exhibits water dispersibility, it can be dispersed in particles without being dissolved in water to form an oil-in-water (O / W) type resin emulsion. The urethane-based resin (A) is preferably contained as resin particles in the ink in a dispersed state.
The urethane resin (A) may be any of an anionic resin, a cationic resin, an amphoteric resin, and a nonionic resin. Many of the coloring materials suitable for water-based inks show anionic properties, especially because the surface charge of the coloring material to be dispersed in water is anionic. Therefore, considering the stability of the coloring material in water, anionic resin, amphoteric resin, and nonion A sex resin can be preferably used.
The water-dispersible urethane resin (A) may be a self-emulsifying resin in which functional groups of the resin are present on the surface of the resin particles, or a surface such as attaching a dispersant to the surface of the resin particles. It may be processed.

The urethane-based resin (A) is preferably a polyether-type aliphatic urethane-based resin having an aliphatic urethane skeleton and having an ether bond in the main chain in addition to the aliphatic urethane skeleton.
As the urethane resin (A), a reaction product of an aliphatic polyisocyanate and a polyether polyol can be used.

As the aliphatic polyisocyanate, an aliphatic polyisocyanate compound having two or more isocyanate groups in one molecule can be used, and an aliphatic diisocyanate is preferable.
In the urethane resin (A), the urethane skeleton portion is an aliphatic urethane skeleton, more preferably the urethane skeleton portion is derived from an aliphatic diisocyanate and has a chain shape, thereby further enhancing the strength of the ink coating film. At the same time, the flexibility of the ink coating film can be further enhanced, the durability of the ink coating film can be further enhanced, and the processability of the ink coating film can be further enhanced.
Further, when the urethane resin (A) synthesized from the aliphatic polyisocyanate is used, yellowing of the urethane resin itself can be prevented, the resin film becomes more transparent, and the color development of the water-based ink is further improved. be able to.

Specific examples of the aliphatic polyisocyanate include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecantryisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and lysine. Diisocyanate, 2,6-diisocyanatomethyl caproate, bis (2-isocyanatoethyl) fumarate, bis (2-isocyanatoethyl) carbonate, 2-isocyanatoethyl-2,6-diisocyanatohexanoate, Examples thereof include isophorone diisocyanate, dicyclohexylmethane 4,4'-diisocyanate, and 1,3-bis (isocyanatomethyl) cyclohexane.
These may be used alone or in combination of two or more.

As the polyether polyol, a polyether compound having two or more hydroxyl groups in one molecule can be used, preferably a chain-like polyether compound having two or more hydroxyl groups, and more preferably a polyether diol. Is.
In the urethane resin (A), the ether bond is a chain ether bond, more preferably the chain is derived from the polyether diol, so that the strength of the ink coating film is further enhanced and the ink coating film is further enhanced. It is possible to further enhance the flexibility of the ink coating film, further enhance the durability of the ink coating film, and further enhance the processability of the ink coating film.
Further, when the urethane resin (A) synthesized from the polyether polyol is used, the ether portion is not affected by hydrolysis, so that the water resistance of the ink coating film can be further improved.
On the other hand, when a urethane resin synthesized from a polyester polyol is used, the ester portion may be hydrolyzed and the image quality, durability and processability of the ink coating film may be deteriorated. Further, when a urethane resin synthesized from a polycarbonate polyol is used, it is possible to form an ink coating film having high durability, but it may not be possible to obtain sufficient processability.

Specific examples of the polyether polyol include polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene ether polyol; ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,5-. Low molecular weight of pentandiol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, trimethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, etc. Examples of the polyol include a polyether polyol obtained by addition-polymerizing ethylene oxide, propylene oxide and the like.
These may be used alone or in combination of two or more.

The urethane-based resin (A) is obtained when a test piece obtained by using a water-dispersible polyether-type aliphatic urethane-based resin (A) as a dry film is immersed in a surfactant to be blended in an ink and taken out 12 hours later. The mass-based swelling rate before immersion is preferably 10% or more and 100% or less.

Here, the swelling rate of the urethane resin (A) is a numerical value obtained by measuring according to the following procedure.
In the combination of the urethane resin (A) and the surfactant mixed in the ink to be measured, the mass ratio at which the urethane resin (A) swells while the urethane resin (A) is immersed in the surfactant. Ask for. When two or more types of urethane-based resin are mixed in the ink to be measured, the mass ratio of the two or more types of urethane-based resin (A) is mixed with the mixing ratio in the ink in the measurement of the swelling rate. Use. Similarly, when two or more types of surfactants are mixed in the ink to be measured, the mass ratio of the two or more types of surfactants is mixed with the mixing ratio in the ink in the measurement of the swelling rate. Use. When the ink to be measured contains a surfactant other than the acetylene glycol-based surfactant (C) having an HLB value of 10.0 or less, the swelling rate is measured with the surfactant (C). It is used by mixing with other surfactants.
The urethane resin (A) has a plurality of ether bonds in its structure. In addition, swelling of the resin occurs when the surfactant enters the gaps in the network structure of the resin. Therefore, the swelling rate can be controlled by adjusting the crystallinity of the urethane resin (A), the molecular weight and ether bond amount in the surfactant, the difference in the solubility parameter between the urethane resin (A) and the surfactant, and the like. become.

Specifically, the urethane resin (A) used for the ink to be measured or a resin emulsion thereof is dried at 100 ° C. to sufficiently evaporate the water content to obtain a dry film of the urethane resin (A). After measuring the mass of the test piece made into a dry film, the test piece is immersed in the surfactant used for the ink to be measured, held for 12 hours and then taken out, and the surface active agent on the surface of the test piece is wiped off to remove the mass of the test piece. To measure. The swelling rate can be calculated from the following formula.
Swelling rate [%] = {((mass of test piece after immersion)-(mass of test piece before immersion)) / (mass of test piece before immersion)} × 100

The swelling rate of the urethane resin (A) may be 0 to 150%, preferably 10 to 100%, more preferably 20 to 80%, and even more preferably 30 to 60%.
The swelling rate of the urethane resin (A) is preferably 10% or more, more preferably 20% or more, still more preferably 30% or more. As a result, in the ink coating film, the urethane resin (A) is appropriately softened by the action of the surfactant, the ink coating film can be more flexible, and the processability of the ink coating film is further enhanced. Can be done.
The swelling rate of the urethane resin (A) is preferably 100% or less, more preferably 80% or less, still more preferably 60% or less. As a result, in the ink coating film, the urethane resin (A) can be prevented from becoming too soft due to the action of the surfactant, the strength of the ink coating film can be further increased, and the durability of the ink coating film can be further improved. Can be enhanced.

The urethane-based resin (A) is preferably a resin that forms a transparent coating film on the base material. Thereby, the influence of the water-based ink on the color development can be reduced. By using a Polytel-based aliphatic urethane-based resin as the urethane-based resin (A), it is possible to prevent yellowing and deterioration of the resin in the heat treatment for forming the ink coating film, and further enhance the color development property of the water-based ink. be able to.

The weight average molecular weight (Mw) of the urethane resin (A) is not particularly limited, but is preferably 1000 to 100,000, more preferably 1500 to 80,000. Here, the weight average molecular weight of the resin is a value in terms of polystyrene by the gel permeation (GPC) method. The following is the same unless otherwise specified.

The urethane-based resin (A) can be blended into the ink as an oil-in-water (O / W) type resin emulsion that becomes particulate in the ink, and is preferably in the state of resin particles in the ink.
The average particle size of the resin particles in the urethane resin (A) ink may be a size suitable for inkjet printing, and the average particle size is generally preferably 300 nm or less. The average particle size is more preferably 250 nm or less, further preferably 200 nm or less, still more preferably 150 nm or less, from the viewpoint of ink ejection property and ink storage stability. Further, when a pigment is used as the coloring material, the average particle size of the resin particles is higher than the average particle size of the pigment (generally about 80 to 200 nm) from the viewpoint of further enhancing the binding property between the pigment particles. Is also preferably small.
The lower limit of the average particle size of the resin particles in the urethane resin (A) ink is not particularly limited, but is preferably 5 nm or more, more preferably 10 nm or more, from the viewpoint of ink storage stability.

In the present specification, unless otherwise specified, the average particle size is a volume-based particle size value (median size) in a particle size distribution measured by a dynamic light scattering method. As the dynamic light scattering type particle size distribution measuring device, a nanoparticle analyzer nanoPartica SZ-100 (HORIBA, Ltd.) or the like can be used.

Commercially available products of the urethane resin (A) resin emulsion include, for example, "Takelac W-5661, W-6020" manufactured by Mitsui Kagaku Co., Ltd., "Permarin UA-200" manufactured by Sanyo Kasei Kogyo Co., Ltd., Daiichi. "Superflex 130", "Superflex 870", "Superflex E-4800" manufactured by Kogyo Seiyaku Co., Ltd., "Adeka Bontita HUX-350", "Adeka Bontita HUX-550" manufactured by Adeka Corporation, Taisei Fine chemical "WBR-016U" and the like can be mentioned (both are trade names).

The urethane-based resin (A) may have a solid content of 0.1 to 15% by mass or 1 to 10% by mass with respect to the total amount of ink. The urethane-based resin (A) has a solid content of preferably 3 to 8% by mass, more preferably 3 to 5% by mass, based on the total amount of ink.
The urethane-based resin (A) has a solid content of 0.1% by mass or more, more preferably 1% by mass or more, still more preferably 3% by mass or more, based on the total amount of ink. The urethane resin (A) alone tends to have a lower film strength than the (meth) acrylic resin (B), but due to the interaction between the urethane resin (A) and the (meth) acrylic resin (B). , The strength of the ink coating film can be further increased, and the durability of the ink coating film can be further improved. Further, by containing a larger amount of the urethane resin (A), the flexibility of the ink coating film can be further enhanced. As a result, when the ink coating film portion of the printed matter is bent or the like, the ink coating film is flexibly deformed along the processed shape, and cracks and whitening phenomena in the processed portion can be further prevented.
The urethane-based resin (A) has a solid content of 15% by mass or less, more preferably 10% by mass or less, still more preferably 8% by mass or less, still more preferably 5% by mass or less, based on the total amount of ink. When the blending amount of the urethane resin (A) is within this range, the amount of the resin content in the ink is appropriately limited while maintaining the blending balance with the (meth) acrylic resin (B) appropriately, and the ink It is possible to further prevent an increase in the viscosity of the ink, and it is possible to further improve the ejection property of the ink.

The urethane-based resin (A) has a mass ratio of solid content of preferably 0.5 to 10 with respect to the coloring material 1, more preferably 1 to 8, and even more preferably 1.5 to 2.

The ink according to one embodiment can contain a water-dispersible (meth) acrylic resin (B).
Here, the (meth) acrylic resin means a polymer containing at least a methacrylic unit, an acrylic unit, or a combination thereof.

Since the (meth) acrylic resin (B) exhibits water dispersibility, it can be dispersed in water without being dissolved in water to form an oil-in-water (O / W) type resin emulsion. .. The (meth) acrylic resin (B) is preferably contained as resin particles in the ink in a dispersed state.
The (meth) acrylic resin (B) may be any of an anionic resin, a cationic resin, an amphoteric resin, and a nonionic resin. Many of the coloring materials suitable for water-based inks show anionic properties, especially because the surface charge of the coloring material to be dispersed in water is anionic. Therefore, considering the stability of the coloring material in water, anionic resin, amphoteric resin, and nonion A sex resin can be preferably used.
The water-dispersible (meth) acrylic resin (B) may be one in which the functional group of the resin is present on the surface of the resin particles, such as a self-emulsifying resin, or a dispersant is attached to the surface of the resin particles. It may be surface-treated such as.

The (meth) acrylic resin (B) is preferably a polymer containing a unit derived from the (meth) acrylic monomer. The (meth) acrylic resin (B) may contain units derived from other monomers as well as units derived from the (meth) acrylic monomer.
Examples of the (meth) acrylic monomer include acrylic acid, methacrylic acid, acrylate, methacrylate, acrylamide, methacrylamide, acrylonitrile, methacrylnitrile, and derivatives thereof. These may be used alone or in combination of two or more.
Examples of other units include styrene unit, vinyl acetate unit, vinyl chloride unit and the like. These may be used alone or in combination of two or more.
Examples of the (meth) acrylic resin (B) include (meth) acrylic polymer, styrene- (meth) acrylic copolymer, vinyl acetate- (meth) acrylic copolymer, and vinyl chloride- (meth) acrylic. Examples thereof include a copolymer or a combination thereof. Preferably, it is a (meth) acrylic polymer, a styrene- (meth) acrylic copolymer, or a combination thereof.

The (meth) acrylic resin (B) is preferably a resin that forms a transparent coating film on the base material. Thereby, the influence of the water-based ink on the color development can be reduced.

The weight average molecular weight (Mw) of the (meth) acrylic resin (B) is not particularly limited, but is preferably 1000 to 100,000, more preferably 5,000 to 80,000.

The (meth) acrylic resin (B) can be blended into the ink as an oil-in-water (O / W) type resin emulsion that becomes particulate in the ink, and is preferably in the state of resin particles in the ink. ..
The average particle size of the resin particles in the ink of the (meth) acrylic resin (B) may be a size suitable for inkjet printing, and shall be in the same numerical range as that of the urethane resin (A) described above. Is preferable.

Commercially available products of the resin emulsion of the (meth) acrylic resin (B) include, for example, "Mobile 9780, 727, 745" and "Mobile 966A, 940" manufactured by Nippon Synthetic Chemical Industry Co., Ltd .; "John" manufactured by BASF Corporation. "Crill 7100, PDX-7370, PDX-7341"; "Boncoat EC-905EF, 5400EF, CG-8400" manufactured by DIC Corporation; "NeoCryl A-1125", "NeoCryl A-1127" and "NeoCryl A-" manufactured by DSM. 6069 ”,“ NeoClyl A-1092 ”,“ NeoClyl A-2092 ”and the like (all are trade names).

The solid content of the (meth) acrylic resin (B) may be 0.1 to 15% by mass or 1 to 10% by mass with respect to the total amount of the ink. The solid content of the (meth) acrylic resin (B) is preferably 1 to 8% by mass, more preferably 2 to 5% by mass, based on the total amount of the ink.
The solid content of the (meth) acrylic resin (B) is preferably 0.1% by mass or more, more preferably 1% by mass or more, still more preferably 2% by mass or more, based on the total amount of the ink. By including the (meth) acrylic resin (B) in this range, the strength of the ink coating film can be further increased, and the durability of the ink coating film can be further improved. The flexibility of the ink coating film tends to be insufficient with the (meth) acrylic resin (B) alone, but the ink is caused by the interaction between the urethane resin (A) and the (meth) acrylic resin (B). Both the strength and flexibility of the coating film can be improved, and the durability and processability of the ink coating film can be further improved.
The solid content of the (meth) acrylic resin (B) is preferably 15% by mass or less, more preferably 10% by mass or less, further preferably 8% by mass or less, still more preferably 5% by mass or less, based on the total amount of ink. .. When the blending amount of the (meth) acrylic resin (B) is within this range, the amount of the resin content in the ink is appropriately limited while maintaining the blending balance with the urethane resin (A) appropriately, and the ink It is possible to further prevent an increase in the viscosity of the ink, and it is possible to further improve the ejection property of the ink.

The (meth) acrylic resin (B) is preferably 0.1 to 8 with respect to the coloring material 1 in terms of mass ratio of solid content, more preferably 0.5 to 5, and even more preferably 1 to 3.

The total amount of the urethane resin (A) and the (meth) acrylic resin (B) is preferably 1% by mass or more, more preferably 3% by mass or more, and 5% by mass or more, based on the total amount of ink. Is even more preferable.
The total amount of the urethane resin (A) and the (meth) acrylic resin (B) in terms of solid content is preferably 20% by mass or less, more preferably 10% by mass or less, and 8% by mass or less, based on the total amount of ink. Is even more preferable.
For example, the total amount of the urethane resin (A) and the (meth) acrylic resin (B) is preferably 1 to 20% by mass, more preferably 3 to 10% by mass, based on the total amount of ink. 5 to 8% by mass is more preferable.

The mass of the urethane-based resin (A) is preferably larger than the mass of the (meth) acrylic-based resin (B) in terms of the mass ratio to be blended in the ink.
The mass ratio of the urethane resin (A) is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, based on the total amount of the urethane resin (A) and the (meth) acrylic resin (B). , 40-70% by mass is more preferable.

The ink according to one embodiment may contain other resins in addition to the urethane-based resin (A) and the (meth) acrylic-based resin (B) described above. For example, as another resin, a binder resin can be blended.
Examples of other resins include other water-dispersible resins, water-soluble resins, and combinations thereof.

Examples of other water-dispersible resins include ethylene-vinyl chloride copolymer resin, styrene-maleic anhydride copolymer resin, vinyl acetate-ethylene copolymer resin and the like. These water-dispersible resins can be blended into the ink as an oil-in-water (O / W) type resin emulsion.
Examples of the water-soluble resin include polyvinyl alcohol, polyacrylic acid, neutralized polyacrylic acid, acrylic acid / maleic acid copolymer, acrylic acid / sulfonic acid copolymer, styrene / maleic acid copolymer and the like. Be done. Further, an anionic water-soluble resin in which an anionic functional group is introduced into these resins can be used.
The above-mentioned other resins may be used alone or in combination of two or more.
The other resin (active ingredient) is preferably 1 to 20% by mass with respect to the total amount of ink. When other resins are mixed in the ink, the total amount of the urethane resin (A) and the (meth) acrylic resin (B) is 50 mass with respect to the total amount of all the resins mixed in the ink. % Or more is preferable, 80% by mass or more is more preferable, and 90% by mass or more is further preferable.

The ink according to one embodiment can contain an acetylene glycol-based surfactant (C) having an HLB value of 10.0 or less.

The acetylene glycol-based surfactant (C) is a glycol having an acetylene group, preferably a glycol having a symmetrical structure in which the acetylene group is located in the center, and has a structure in which ethylene oxide is added to acetylene glycol. You may prepare.
When acetylene glycol to which ethylene oxide is added is used as the acetylene glycol-based surfactant (C), the number of moles of ethylene oxide added is preferably 5 or less, more preferably 4 or less, still more preferably 3 or less.

The acetylene glycol-based surfactant (C) preferably has an HLB value of 10.0 or less, more preferably 9.0 or less, more preferably 8.0 or less, and may be 5.0 or less. As a result, the coatability of the resin component contained in the ink, particularly the urethane resin (A), can be further improved, the strength of the ink coating film can be further improved, and the durability of the ink coating film can be further improved. Can be enhanced. Further, since the urethane resin (A) is applied more uniformly, the flexibility of the ink coating film can be further improved, and the processability of the ink coating film can be further improved.
The lower limit of the HLB value of the acetylene glycol-based surfactant (C) is not particularly limited, but from the viewpoint of ink storage stability, 1.0 or more is preferable, 2.0 or more is more preferable, and 3.0 or more. It may be.
For example, the acetylene glycol-based surfactant (C) preferably has an HLB value of 1.0 or more and 10.0 or less, more preferably 2.0 or more and 8.0 or less, and even more preferably 3.0 or more and 5.0 or less. ..

Here, the HLB value is one of the scales showing the properties of the surfactant, and is a numerical value of the balance between the hydrophilic group and the lipophilic group in the molecule. The HLB value has been proposed by several calculation methods, but in the present specification, it is a value calculated by the Griffin method, and is calculated by the following formula (1).
HLB value = 20 x (formula weight of hydrophilic part) / (molecular weight of surfactant) ... formula (1)

Here, the "hydrophilic portion" indicates a hydrophilic portion contained in the molecular structure of the surfactant, preferably a polyoxyalkylene group, an alcohol group having 3 or less carbon atoms in the main chain with respect to the hydroxyl group, and the like. Or a combination of these. When the surfactant contains a plurality of hydrophilic portions, the formula amount of the hydrophilic portion in the above formula (1) is the total amount of these.
Examples of the polyoxyalkylene group include a polyoxyethylene group (polyethylene oxide; EO:-(CH ₂ CH ₂ O) _n- ) and a polyoxypropylene group (polypropylene oxide; PO:-(CH ₂ CH ₂ CH ₂ O) _n-). -) Etc. can be mentioned.
The alcohol group includes groups derived from methanol, ethanol, propanol, isopropanol, glycerin, polyglycerin, trimethylolpropane, pentaerythritol, sorbitol, sorbitan, sucrose (sucrose), mannit, glycols and the like (for example, ethanol). If so, −CH ₂ CH ₂ OH) can be mentioned.

The "hydrophobic portion" indicates a hydrophobic portion contained in the molecular structure of the surfactant. For example, a fat derived from an aliphatic alcohol, an alkylphenol, a fatty acid or the like having a main chain having 4 or more carbon atoms with respect to a hydroxyl group. Group hydrocarbon groups, aromatic hydrocarbon groups, organic siloxanes, alkyl halides, etc., or combinations thereof.

As commercially available products of the acetylene-based surfactant (C) having an HLB value of 10.0 or less, for example, "Orfin E1004", "Surfinol 420, 440, 104" (all manufactured by Nisshin Chemical Industry Co., Ltd.) and the like are used. Can be listed (both are product names).
The above-mentioned acetylene glycol-based surfactant (C) may be used alone or in combination of two or more.

The amount of the active ingredient of the surfactant (C) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, based on the total amount of the ink. As a result, in forming a coating film using the urethane resin (A) and the (meth) acrylic resin (B), the affinity with the base material to which the ink is applied can be further improved, and the ink coating film becomes stronger. Can be formed, and the durability of the ink coating film can be further enhanced. Further, the urethane resin (A) swells due to the action of the surfactant to further impart flexibility, and the processability of the ink coating film can be further improved.
The amount of the active ingredient of the surfactant (C) is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, based on the total amount of the ink. This makes it possible to prevent a decrease in storage stability of the ink.
For example, the amount of the active ingredient of the surfactant (C) is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, still more preferably 1 to 3% by mass, based on the total amount of the ink.

The surfactant (C) is preferably 0.1 to 1 and more preferably 0.2 to 0.5 in terms of the mass ratio of the amount of the active ingredient to the solid content of the urethane resin (A).
The surfactant (C) preferably has a mass ratio of 0.1 to 2 and more preferably 0.5 to 1 in terms of the mass ratio of the amount of the active ingredient to the amount of the solid content of the (meth) acrylic resin (B).

The ink according to one embodiment may contain other surfactants in addition to the above-mentioned surfactant (C). As the other surfactant, a nonionic surfactant, an anionic surfactant, or a combination thereof can be preferably used, and a nonionic surfactant is more preferable.
As another surfactant, an acetylene glycol-based surfactant having an HLB value greater than 10.0 may be used.
Examples of commercially available acetylene-based surfactants having an HLB value greater than 10.0 include "Orfin E1010, E1006, E1020" and "Surfinol 465, 485" (all manufactured by Nissin Chemical Industry Co., Ltd.). Can be (both are product names).

Further, as other surfactants, for example, ester-type surfactants such as glycerin fatty acid ester and fatty acid sorbitan ester; ether-type surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether and polyoxypropylene alkyl ether. Agents; ether ester-type surfactants such as polyoxyethylene sorbitan fatty acid ester; acetylene alcohol-based surfactants; surfactants having an acetylene group; silicone-based surfactants; fluorine-based surfactants and the like. Among them, an acetylene alcohol-based surfactant, a surfactant having an acetylene group, and a silicone-based surfactant can be preferably used.

When other surfactants are blended in the ink, the surfactant (C) preferably has a mass ratio of 50% by mass or more, more preferably 80% by mass or more, based on the total amount of the surfactant. More preferably, 90% by mass or more.

The ink can include a coloring material. The coloring material may include pigments, dyes, or combinations thereof. Pigments can be preferably used from the viewpoint of weather resistance and color development of the image.

The pigment can be preferably blended in the ink as a pigment dispersion.
The pigment dispersion may be one in which the pigment can be dispersed in a solvent and the pigment is in a dispersed state in the ink. For example, a pigment dispersed in water with a pigment dispersant, a self-dispersing pigment dispersed in water, a microencapsulated pigment in which the pigment is coated with a resin, and the like dispersed in water can be used. ..

As the pigment, for example, organic pigments such as azo pigments, phthalocyanine pigments, polycyclic pigments and dyed lake pigments; and inorganic pigments such as carbon black and metal oxides can be used. Examples of the azo pigment include soluble azo lake pigments, insoluble azo pigments and condensed azo pigments. Examples of the phthalocyanine pigment include metal phthalocyanine pigments such as copper phthalocyanine pigments and metal-free phthalocyanine pigments. Polycyclic pigments include quinacridone pigments, perylene pigments, perinone pigments, isoindolin pigments, isoindolinone pigments, dioxazine pigments, thioindigo pigments, anthracinone pigments, quinophthalone pigments, and metal complex pigments. , And diketopyrrolopyrrole (DPP) and the like. Examples of carbon black include furnace carbon black, lamp black, acetylene black, and channel black.

Further, examples of the organic pigment include Brilliant Carmine 6B, Lake Red C, Watching Red, Disazo Yellow, Hansa Yellow, Phthalocyanine Blue, Phthalocyanine Green, Alkaline Blue, Aniline Black and the like.
Examples of the inorganic pigment include metals such as cobalt, iron, chromium, copper, zinc, lead, titanium, vanadium, manganese, and nickel, metal oxides and sulfides thereof, and ocher, ultramarine blue, and dark blue. ..
Moreover, you may use a white pigment as a pigment. Examples of the white pigment include inorganic pigments such as titanium oxide, zinc oxide, zinc sulfide, antimony oxide, and zirconium oxide.

Specific examples of pigments include Pigment Yellow 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 94, 95, 109, 110, 117, 120, 125, 128, 137, 138, 139. 147, 148, 150, 151, 154, 155, 166, 168, 180, 185; Pigment Orange 16, 36, 38, 43, 51, 55, 59, 61, 64, 65, 71; Pigment Red 9, 48 , 49, 52, 53, 57, 97, 122, 149, 168, 177, 178, 179, 206, 207, 209, 242, 254, 255; Pigment Violet 19, 23, 29, 30, 37, 40, 50 Pigment Blue 15, 15: 1, 15: 3, 15: 4, 15: 6, 22, 30, 64, 80; Pigment Green 7 (Chlorinated Phthalocyanine Green), 36 (Brominated Phthalocyanine Green); Pigment Brown 23 , 25, 26; Pigment Black 7 (carbon black), 26, 27, 28 and the like.

Commercially available examples of carbon black include Monarch 1000, ELFTEX 415 (above, carbon black manufactured by Cabot Corporation), # 960, # 970, MA8, MA77 (above, carbon black manufactured by Mitsubishi Chemical Corporation) and the like.
Commercially available examples of color pigments include LIONOL BLUE FG-7400G (phthalocyanine pigment manufactured by Toyo Ink Mfg. Co., Ltd.); YELLOW PIGMENT E4GN (nickel complex azo pigment manufactured by Bayer); RG (DIC quinacridone pigment); Fastogen Super Magenta RGT (DIC quinacridone pigment); YELLOW PIGMENT E4GN (Rankses nickel complex azo pigment); Ilgarite Blue 8700 (BASF phthalocyanine pigment); E4GN-GT Nickus complex azo pigments manufactured by Rankses); Fastogen Blue TGR (cyan pigments manufactured by DIC Co., Ltd.); Cinquasia Magenta D4550J (magenta pigments manufactured by BASF); Inkjet Yellow 4GP (yellow pigments manufactured by Clariant) and the like.

The average particle size of these pigments is preferably 50 to 500 nm, more preferably 50 to 200 nm. The average particle size of these pigments is preferably 50 nm or more from the viewpoint of color development, and preferably 500 nm or less from the viewpoint of discharge stability.

In order to stably disperse the pigment in the ink, a pigment dispersant typified by a polymer dispersant or a surfactant can be preferably used.
Commercially available polymer dispersants include, for example, the TEGO Disperse series "TEGO Disperse 740W, 750W, 755W, 757W, 760W" manufactured by EVONIK, and the Solsperse series "Solsperse 20000, 27000" manufactured by Nippon Lubrizol Co., Ltd. 41000, 41090, 43000, 44000, 46000 ", John Krill series" John Krill 57, 60, 62, 63, 71, 501 "manufactured by Johnson Polymer," DISPERBYK-102, 185, 190, 193, manufactured by BYK. 199 ”, polyvinylpyrrolidone“ K-30, K-90 ”manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., etc. (both are trade names).

As the surfactant-type dispersant, a nonionic surfactant can be preferably used in consideration of the dispersion stability of the pigment in the ink and the influence of ionicity from the pretreatment agent.
Nonionic surfactants such as the Emulgen series "Emulgen A-60, A-90, A-500, B-40, L-40, 420" manufactured by Kao Corporation as commercially available surfactant-type dispersants. Examples include agents (both are product names).

These pigment dispersants can be used alone or in combination of two or more.
When a pigment dispersant is used, the amount of the pigment dispersant added varies depending on the type and is not particularly limited. For example, the pigment dispersant can be added in the range of 0.005 to 0.5 with respect to the pigment 1 in terms of the mass ratio of the active ingredient.

A self-dispersing pigment may be blended as a coloring material. A self-dispersing pigment is a pigment in which a hydrophilic functional group is introduced into the surface of the pigment by a chemical treatment or a physical treatment. The hydrophilic functional group to be introduced into the self-dispersible pigment is preferably an ionic one, and by charging the pigment surface anionicly or cationically, the pigment particles are stably dispersed in water by electrostatic repulsive force. be able to. As the anionic functional group, a sulfonic acid group, a carboxy group, a carbonyl group, a hydroxy group, a phosphonic acid group and the like are preferable. As the cationic functional group, a quaternary ammonium group, a quaternary phosphonium group and the like are preferable.

These hydrophilic functional groups may be bonded directly to the pigment surface or may be bonded via other atomic groups. Examples of other atomic groups include, but are not limited to, an alkylene group, a phenylene group, a naphthylene group and the like. Examples of the pigment surface treatment method include diazotization treatment, sulfonation treatment, hypochlorous acid treatment, humic acid treatment, vacuum plasma treatment and the like.

Examples of the self-dispersing pigment include CAB-O-JET series "CAB-O-JET200, 300, 250C, 260M, 270" manufactured by Cabot Corporation, and "BONJET BLACK CW-1, CW-2" manufactured by Orient Chemical Industries Co., Ltd. , CW-4 "and the like can be preferably used (all are trade names).

A pigment dispersion in which pigments are pre-dispersed with a pigment dispersant may be used. Examples of commercially available products of pigment dispersions dispersed with pigment dispersants include HOSTAJET series manufactured by Clariant AG and FUJI SP series manufactured by Fuji Dye Co., Ltd. (both are trade names). A pigment dispersion dispersed with the above-mentioned pigment dispersant may be used. Further, a microencapsulated pigment in which the pigment is coated with a resin may be used.

A dye may be blended as a coloring material. As the dye, a dye generally used in the technical field of printing can be used, and the dye is not particularly limited. Specific examples thereof include basic dyes, acidic dyes, direct dyes, soluble bat dyes, acidic medium dyes, medium dyes, reactive dyes, bat dyes, sulfide dyes and the like. Of these, those that are water-soluble and those that become water-soluble by reduction or the like can be preferably used. More specifically, azo dyes, rhodamine dyes, methine dyes, azomethine dyes, xanthene dyes, quinone dyes, triphenylmethane dyes, diphenylmethane dyes, methylene blue and the like can be mentioned.

The above-mentioned coloring materials can be used alone or in combination of two or more.
The amount of the active ingredient of the coloring material is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass, still more preferably 2 to 5% by mass, based on the total amount of the ink.

The ink preferably contains water as the aqueous solvent, and the main solvent may be water. When water is contained as a solvent in the above-mentioned resin emulsion, pigment dispersion, or the like, the water in each component is converted into a part of the water in the ink to prepare the ink.
The water is not particularly limited, but water containing as little ionic component as possible is preferable. In particular, from the viewpoint of ink storage stability, it is preferable that the content of multivalent metal ions such as calcium is low. As the water, for example, ion-exchanged water, distilled water, ultrapure water, or the like may be used.
From the viewpoint of adjusting the ink viscosity, water is preferably contained in an amount of 20 to 90% by mass, more preferably 30 to 80% by mass, based on the total amount of the ink.

The ink can contain a water-soluble organic solvent. The water-soluble organic solvent preferably exhibits compatibility with water. As the water-soluble organic solvent, an organic compound that is liquid at room temperature and can be dissolved or mixed in water can be used, and a water-soluble organic solvent that uniformly mixes with the same volume of water at 20 ° C. at 1 atm is used. Is preferable.

Examples of the water-soluble organic solvent include lower alcohols such as methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol and 2-methyl-2-propanol; ethylene glycol, diethylene glycol and triethylene. Glycols such as glycol, tetraethylene glycol, pentaethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propanediol; glycerins such as glycerin, diglycerin, triglycerin, polyglycerin; monoacetin, diacetin Acetins such as: ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether. , Triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether and other glycol ethers; Triethanolamine, 1-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, β-thiodiglycol, sulfolane and the like can be used.
These may be used alone, or may be used in combination of two or more as long as they form a single phase.

Among the water-soluble organic solvents, glycols, glycol ethers, and combinations thereof are preferably used, and more preferably glycol ethers. These water-soluble organic solvents have better compatibility with water. The dispersion stability of the urethane-based resin (A) and the (meth) acrylic-based resin (B) can be further improved in a mixed solvent of these water-soluble organic solvents and water.
Further, among the water-soluble organic solvents, it is preferable to use a low-polarity solvent. Surfactants with low HLB values are difficult to dissolve in aqueous solvents and may float in the ink. In this case, by adding a low-polarity solvent to the ink, the solubility of the surfactant having a low HLB value can be enhanced. Examples of the low polar solvent include diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, triacetin, 3,5,5-trimethyl-2-cyclohexene-1-one, 2-one. Pyrrolidone and the like can be preferably used.

The water-soluble organic solvent can be contained in an amount of 1 to 80% by mass, more preferably 10 to 60% by mass, and 20 to 50% by mass, based on the total amount of the ink, from the viewpoint of viscosity adjustment and moisturizing effect. More preferred.
The low-polarity water-soluble organic solvent is preferably 1 to 20% by mass, more preferably 1 to 10% by mass, still more preferably 2 to 3% by mass.

In addition to the above components, the ink may optionally contain a wetting agent (moisturizer), surface tension adjusting agent (penetrating agent), defoaming agent, fixing agent, pH adjusting agent, antioxidant, preservative, etc. It can be appropriately contained.

A known pH regulator can also be added to adjust the pH of the ink. Sulfuric acid, nitric acid, acetic acid, sodium hydroxide, potassium hydroxide, ammonium hydroxide, triethanolamine and the like can be used as a pH adjuster or as an ink thickening aid.

By blending an antioxidant, it is possible to prevent the oxidation of ink components and improve the storage stability of the ink. As the antioxidant, for example, L-ascorbic acid, sodium L-ascorbic acid, sodium isoascorbic acid, potassium sulfite, sodium sulfite, sodium thiosulfate, sodium sulfite, sodium pyrosulfite and the like can be used.

By blending an antiseptic, it is possible to prevent the ink from spoiling and improve the storage stability. Examples of preservatives include 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 1 , 2-Benzothiazolinone-3-one and other isothiazolinone preservatives; hexahydro-1,3,5-tris (2-hydroxyethyl) -s-triazine and other triazine preservatives; 2-pyridinethiolsodium-1- Ppyridine / quinoline preservatives such as oxide and 8-oxyquinolin; dithiocarbamate preservatives such as sodium dimethyldithiocarbamate; 2,2-dibromo-3-nitrilopropionamide, 2-bromo-2-nitro-1,3 Organic bromine-based preservatives such as -propanediol, 2,2-dibromo-2-nitroethanol, 1,2-dibromo-2,4-dicyanobutane; methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, sorbin Potassium acid, sodium dehydroacetate, salicylic acid and the like can be used.

The appropriate range of the viscosity of the ink varies depending on the nozzle diameter of the ejection head, the ejection environment, etc., but in general, it is preferably 1 to 30 mPa · s, more preferably 5 to 15 mPa · s at 23 ° C. Suitable for inkjet printing equipment.

The method for producing the ink is not particularly limited, but a desired ink can be obtained by appropriately mixing each component. For example, when a pigment dispersion is used as a coloring material, a mixture of a pigment, a pigment dispersant, and water is dispersed using a disperser such as a bead mill to obtain a pigment dispersion, and then a pigment dispersion and a urethane-based material are used. An ink can be obtained by mixing a resin emulsion of a resin (A), a resin emulsion of a (meth) acrylic resin (B), a surfactant (C), water, and a water-soluble organic solvent all at once or by dividing them. .. Further, the obtained composition may be filtered using a filter or the like.

The resin emulsion of the urethane-based resin (A) to be blended in the ink preferably has a solid content of 10 to 50% by mass, more preferably 30 to 40% by mass.
The resin emulsion of the urethane resin (A) to be blended in the ink preferably has a viscosity of 1 to 300 mPa · s in the state of the emulsion, more preferably 1 to 100 mPa · s.
The resin emulsion of the (meth) acrylic resin (B) to be blended in the ink preferably has a solid content of 10 to 50% by mass.
The resin emulsion of the (meth) acrylic resin (B) to be blended in the ink preferably has a viscosity of 1 to 300 mPa · s at 23 ° C. in the state of the emulsion, more preferably 1 to 100 mPa · s.
In order to perform high-quality printing on various substrates with different surface energies, it is important that the ink spreads easily. Therefore, it is preferable that the viscosity of the resin emulsion in the ink is low.

The water-based inkjet ink according to the embodiment may be printed on an untreated substrate, or may be printed on a substrate treated with a pretreatment agent. In particular, when a low-permeability base material is used as the base material, the water-based inkjet ink does not easily penetrate into the base material, so it is preferable to treat the base material with a pretreatment agent.
The pretreatment agent preferably contains, for example, a surfactant, a flocculant, inorganic particles, or a combination thereof together with an aqueous medium. More preferably, the pretreatment agent comprises an aqueous medium and a surfactant and / or flocculant. Further, the pretreatment agent may contain a binder resin in order to fix the flocculant to the substrate.
The amount of the active ingredient of the surfactant is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, still more preferably 0.7 to 2% by mass, based on the total amount of the pretreatment agent.
The amount of the active ingredient of the binder resin is preferably 0.5 to 20.0% by mass with respect to the total amount of the pretreatment agent.

By treating the base material with a coagulant, when the water-based inkjet ink is applied to the base material, the color material components in the ink are coagulated on the base material to further enhance the color development property of the printed matter. Can be done.
As the flocculant, a cationic resin, a polyvalent metal salt, an organic acid, an inorganic acid, a salt of an inorganic acid, or a combination thereof can be used. The cationic resin may be a cationic water-soluble resin, a cationic water-dispersible resin, or a combination thereof.
The total amount of the flocculant containing the cationic resin, the polyvalent metal salt, the organic acid, and the inorganic acid is preferably 1 to 50% by mass, more preferably 3 to 20% by mass, based on the total amount of the pretreatment agent.

The pretreatment agent preferably contains water as an aqueous solvent, and the main solvent may be water.
The pretreatment agent can contain a water-soluble organic solvent from the viewpoint of viscosity adjustment and moisturizing effect.
As the water and the water-soluble organic solvent, those described in the above-mentioned ink can be used.
Further, in addition to the above-mentioned components, the pretreatment agent may optionally include a wetting agent (moisturizer), a surface tension adjusting agent (penetrating agent), a defoaming agent, a fixing agent, an antioxidant, a preservative, a pH adjusting agent, etc. Can be appropriately contained.

"Manufacturing method of printed matter"
Hereinafter, an example of a method for manufacturing a printed matter will be described.
A method for producing a printed matter can include, for example, forming an image on a substrate using a water-based inkjet ink. As the water-based inkjet ink, the above-mentioned water-based inkjet ink can be used.
It can also include treating the substrate with a pretreatment agent prior to image formation by aqueous inkjet.
Further, the base material may be white-painted with white ink before the image is formed on the base material using the water-based inkjet ink. Thereby, the color development property of the ink coating film by the water-based inkjet ink can be further enhanced. The white ink is not particularly limited, and an ink having a white pigment as a coloring material may be used in an ink having a usual formulation, or an ink containing a white pigment as a coloring material in the water-based inkjet ink according to one embodiment may be used. good.

As a method of forming an image on a base material using an aqueous inkjet ink, an inkjet printing method can be used. The inkjet printing method can form an image easily and freely on demand without contacting the base material.
The inkjet printing apparatus may be of any method such as a piezo method, an electrostatic method, or a thermal method. Ink is ejected from the inkjet head based on a digital signal, and the ejected ink droplets are used as a base material. Make it adhere.

The obtained printed matter is preferably heat-treated to remove volatile matter. The heat treatment temperature is preferably 25 ° C. to 150 ° C., more preferably 50 ° C. to 120 ° C.
In one embodiment, since the ink contains a urethane resin (A) and a (meth) acrylic resin (B), the resin component in the ink is melted or softened by heat treatment of the obtained printed matter to be uniform. A good coating film can be formed, the strength and flexibility of the ink coating film can be further enhanced, and the durability and processability of the ink coating film can be further enhanced.
Further, when the (meth) acrylic resin (B) is used, the durability of the ink coating film can be further enhanced by using it in combination with a cross-linking agent having a property of cross-linking by an external stimulus such as heat. As such a (meth) acrylic resin (B), one having a carboxy group, a glycidyl group, a ketone group or the like as a functional group is preferable. Examples of the cross-linking agent that can be preferably used in combination with the (meth) acrylic resin (B) include (poly) carbodiimide compounds, (poly) isocyanate compounds, epoxy compounds, silyl compounds, oxazoline compounds, and hydrazine compounds.

After applying the ink to the base material, a step of post-treating the base material to form an overcoat layer may be further provided. As a method of post-treating the base material, a post-treatment agent can be applied to the base material. Since the ink according to one embodiment contains a resin component in the ink itself, a resin film can be formed only with the ink to sufficiently obtain the strength and flexibility of the ink coating film, and the durability and processing of the ink coating film can be obtained. Although the properties can be further enhanced, an overcoat layer may be further formed depending on the application.
As the post-treatment agent, for example, a post-treatment liquid containing a resin capable of forming a film and an aqueous medium or an oil-based medium can be used.

According to one embodiment, it is possible to provide an ink set containing a water-based inkjet ink and a pretreatment agent. As the water-based inkjet ink and the pretreatment agent, the above-mentioned ones can be used respectively. The ink set may further contain other inks and / or post-treatment agents.

The water-based inkjet ink according to one embodiment can be applied to both a permeable base material and a low permeable base material. Above all, the strength and flexibility of the ink coating film can be further improved with respect to the low-permeability base material, and the durability and processability of the ink coating film can be further improved.

The low-permeability base material is a base material in which the liquid does not permeate into the base material, and specifically, a base material in which most of the liquid in the ink stays on the surface of the base material.
Examples of the low-permeability base material include metal base materials such as metal plates such as aluminum, iron, copper, titanium, tin, chromium, cadmium, and alloys (for example, stainless steel, steel, etc.); borosilicate glass, quartz glass, soda. Glass base material such as flat glass such as lime glass; resin sheet such as PET film, OHT sheet, polyester sheet, polypropylene sheet, resin base material such as acrylic plate; molded body such as alumina, zirconia, steatite, silicon nitride, etc. Ceramic base material and the like.
These base materials may have a plating layer, a metal oxide layer, a resin layer, or the like formed on them, or may be surface-treated using a surfactant, a corona treatment, or the like. The water-based inkjet ink according to one embodiment can exert its effect even when it is treated on an untreated substrate.

Examples of the permeable base material include printing paper such as plain paper, coated paper, and special paper; cloth such as textiles and unemployed cloth; porous building materials for humidity control, sound absorption, and heat insulation; wood, concrete, etc. Examples include porous materials.

The printed matter according to one embodiment has a base material and an ink image layer formed on the base material, and the ink image layer is a water-dispersible polyether type aliphatic urethane resin (A) and a water-dispersible acrylic. It can contain a based resin (B), an acetylene glycol-based surfactant (C) having an HLB value of 10.0 or less, and a coloring material.
According to this, it is possible to provide a printed matter having excellent durability and processability of a printed image. Further, according to one embodiment, it is possible to provide a printed matter having excellent image quality of a printed image.
In particular, when a decorative article is produced using a rigid base material such as a metal base material as the base material, the processed portion is formed because the ink coating film has flexibility when bending or the like in the printed portion. It is possible to prevent the phenomenon of cracking and whitening of the printed image.
The details of the base material, the urethane-based resin (A), the (meth) acrylic-based resin (B), the surfactant (C), and the coloring material in the printed matter are as described above.

"Ink set"
Hereinafter, the ink set according to one embodiment will be described. In the following description, the parts not particularly described are as described in the above-mentioned method for manufacturing the water-based inkjet ink and printed matter, and the description of the parts common to the above-mentioned method for manufacturing the water-based inkjet and printed matter is omitted. There is.

The ink set according to one embodiment includes a water-based inkjet ink and a maintenance liquid, and the water-based inkjet ink includes a water-dispersible polyether type aliphatic urethane resin (A) and a water-dispersible (meth) acrylic resin (meth). B), an acetylene glycol-based surfactant (C) having an HLB value of 10.0 or less, a coloring material, and water, and the maintenance liquid contains an acetylene glycol-based surfactant having an HLB value of 10.0 or less (C). It is characterized by containing C') and a maintenance liquid containing 30% by mass or more of glycerin with respect to the total amount of the maintenance liquid.
According to the ink set according to one embodiment, it is possible to provide a printed matter having excellent durability and processability of the printed image, and it is possible to improve the continuous ejection property of the water-based inkjet ink. Further, according to the ink set according to one embodiment, it is possible to provide a printed matter having excellent uniformity of a printed image.

The maintenance liquid is a liquid for cleaning members such as the nozzle surface of the nozzle head and the inside of the nozzle head in an inkjet printing apparatus. Since ink easily adheres to the nozzle surface near the nozzle discharge port, the inside of the head, etc., a maintenance liquid can be used to remove the ink stains by cleaning. With ordinary water-based ink, even if water is used as the maintenance liquid, the ink is removed by the action of mixing the water and the ink, and cleaning becomes possible. Since acetylene glycol-based surfactants with low HLB values are less soluble in water than surfactants with high HLB values, after printing with an aqueous ink containing acetylene glycol-based surfactants with low HLB values, only with water. When the nozzle surface, the inside of the head, etc. are washed, the surfactant in the ink may not be washed away but may be adsorbed on the wall surface such as the nozzle surface, the inside of the head, etc. and remain. If the amount of this adsorbed substance increases, the nozzle discharge port may be blocked and the discharge reliability such as image uniformity and continuous discharge may decrease.

In cleaning the nozzle surface, if the combination is not such that the ink and the maintenance liquid can be sufficiently mixed, the nozzle surface cannot be sufficiently cleaned, and the nozzle ejection port may be blocked to cause ejection failure. By forming a stable mixture of the ink and the maintenance liquid on the nozzle surface, the removal of the ink is promoted and the nozzle surface can be appropriately cleaned.
By using a maintenance liquid that can be mixed with the water-based ink according to one embodiment at an arbitrary ratio, the cleaning efficiency can be further improved. Further, even when the miscibility containing the ink and the maintenance liquid is concentrated on the nozzle surface, the miscibility is maintained, so that the generation of foreign substances in the concentrated mixed liquid can be suppressed. For example, when the maintenance liquid is applied in a state where the ink adhering to the nozzle surface is concentrated, or when the volatile component of the maintenance liquid is volatilized and the maintenance liquid is concentrated after the maintenance liquid is applied to the nozzle surface. In addition, it is possible to suppress the occurrence of agglomeration of ink pigments, resin emulsions, etc. in the concentrated admixture.

The maintenance liquid contains an acetylene glycol-based surfactant having a low HLB value as a component common to the ink, and this surfactant is preferably contained in the maintenance liquid in a dissolved state. This maintenance liquid can maintain the stability of the mixing liquid even if it is mixed with the ink at an arbitrary ratio on the nozzle surface, and can prevent the agglomeration of pigments, resin emulsions, etc. derived from the ink, resulting in image uniformity and continuity. Dischargeability can be improved.
Further, since the maintenance liquid contains 30% by mass or more of glycerin, the moisturizing property of the maintenance liquid is enhanced, and even if the maintenance liquid alone or the mixed liquid with ink is in an open state to the atmosphere, agglomerates due to rapid evaporation of water. Occurrence can be suppressed. Further, when the maintenance liquid contains glycerin, the ratio of water content is relatively small, so that the ratio of water is also small in the mixed liquid of the ink and the maintenance liquid, and the acetylene glycol-based surfactant having a low HLB value in the mixed liquid is used. The activator can be maintained in a dissolved state, and the uniformity of the image and the continuous ejection property can be improved.

As the water-based inkjet ink provided in the ink set, the above-mentioned water-based inkjet ink can be used. Details are as described above.
The maintenance liquid provided in the ink set can include an acetylene glycol-based surfactant (C') having an HLB value of 10.0 or less and glycerin. Hereinafter, the acetylene glycol-based surfactant (C') having an HLB value of 10.0 or less is also referred to as a surfactant (C').

As the acetylene glycol-based surfactant (C') contained in the maintenance liquid, a component common to the acetylene glycol-based surfactant (C) contained in the above-mentioned aqueous inkjet ink can be used. The type of acetylene glycol-based surfactant may be the same or different between the maintenance liquid and the water-based inkjet ink. The maintenance liquid and the water-based inkjet ink may contain one or more acetylene glycol-based surfactants, respectively. When at least one of the maintenance liquid and the water-based inkjet ink contains two or more kinds of acetylene glycol-based surfactants, a part or all of the acetylene glycol-based surfactant is used between the maintenance liquid and the water-based inkjet ink. It may be the same or all may be different.
The acetylene glycol-based surfactant (C) contained in the water-based inkjet ink and the acetylene glycol-based surfactant (C') contained in the maintenance liquid preferably contain the same components. As a result, when the maintenance liquid and the ink are mixed on the nozzle surface in maintenance, the stability of the mixed liquid can be further improved, and the continuous ejection property can be improved.

The amount of the active ingredient of the surfactant (C') is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, based on the total amount of the maintenance liquid. This makes it possible to provide a maintenance liquid that exhibits miscibility with water-based inks containing an acetylene glycol-based surfactant having a low HLB value and suppresses the generation of foreign substances. This maintenance liquid can more efficiently remove ink stains adhering to the nozzle surface, including the surfactant in the ink, and can improve the uniformity of the image and the continuous ejection property.
The amount of the active ingredient of the surfactant (C') is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, based on the total amount of the maintenance liquid.
For example, the amount of the active ingredient of the surfactant (C') is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, and further 1 to 3% by mass with respect to the total amount of the maintenance liquid. preferable.

The maintenance liquid may contain other surfactants in addition to the above-mentioned surfactant (C'). As the other surfactant, a nonionic surfactant, an anionic surfactant, or a combination thereof can be preferably used, and a nonionic surfactant is more preferable. As other surfactants, for example, other surfactants described in the above-mentioned water-based inkjet ink can be mentioned.
When other surfactants are blended in the ink, the surfactant (C') is preferably 50% by mass or more, more preferably 80% by mass or more, in terms of the mass ratio of the active ingredient with respect to the total amount of the surfactant. , 90% by mass or more is more preferable.

The maintenance liquid can contain an aqueous solvent. The aqueous medium may be a water-soluble organic solvent, water, or a combination thereof.
Examples of the water-soluble organic solvent contained in the maintenance liquid include the water-soluble organic solvent described in the above-mentioned water-based inkjet ink.

Among the water-soluble organic solvents, glycerins, glycols, glycol ethers, and combinations thereof are preferably used, more preferably glycerins, and specifically glycerin. These water-soluble organic solvents have better compatibility with water and also have good affinity with acetylene alcohol-based surfactant (C').

The maintenance liquid preferably contains glycerin.
The amount of glycerin is preferably 20% by mass or more, more preferably 30% by mass or more, based on the total amount of the maintenance liquid. As a result, the moisturizing property of the maintenance liquid can be enhanced, and the evaporation of water from the cleaning surface can be reduced. For example, even if the maintenance liquid alone or the mixed liquid with ink is open to the atmosphere on the cleaning surface, the generation of agglomerates due to the rapid evaporation of water can be suppressed, and the uniformity of the image and the continuous ejection property are improved. be able to.
The amount of glycerin is preferably 50% by mass or less, more preferably 40% by mass or less, and may be 35% by mass or less based on the total amount of the maintenance liquid. As a result, it is possible to suppress the rapid thickening of the maintenance liquid when the water evaporates.
For example, glycerin is preferably 20 to 50% by mass, more preferably 30 to 40% by mass, still more preferably 30 to 35% by mass, based on the total amount of the maintenance liquid.

Further, among the water-soluble organic solvents, it is preferable to use a low-polarity solvent. Surfactants with low HLB values are difficult to dissolve in aqueous solvents and may float in the maintenance solution. In this case, by adding a low-polarity solvent to the maintenance solution, the solubility of the surfactant having a low HLB value can be enhanced. Examples of the low polar solvent include diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, triacetin, 3,5,5-trimethyl-2-cyclohexene-1-one, 2-one. Pyrrolidone and the like can be preferably used.

From the viewpoint of viscosity adjustment and moisturizing effect, the water-soluble organic solvent can be contained in an amount of 20 to 80% by mass, more preferably 30 to 60% by mass, and more preferably 30 to 50% by mass, based on the total amount of the maintenance liquid. Is more preferable.
The low-polarity water-soluble organic solvent is preferably 1 to 20% by mass, more preferably 1 to 10% by mass, still more preferably 2 to 3% by mass, based on the total amount of the maintenance liquid.

The maintenance liquid can contain water together with a water-soluble organic solvent.
The amount of water is preferably 60% by mass or less, more preferably 50% by mass or less, based on the total amount of the maintenance liquid. As the water content increases, the surfactant having a low HLB value is likely to precipitate. Therefore, when the water content is smaller, the precipitation of the surfactant having a low HLB value can be suppressed.
The amount of water is preferably 30% by mass or more, more preferably 40% by mass or more, based on the total amount of the maintenance liquid. Thereby, the water-based component contained in the water-based ink can be dissolved or dispersed and removed.
For example, water is preferably 30 to 60% by mass, more preferably 40 to 60% by mass, still more preferably 40 to 50% by mass, based on the total amount of the maintenance liquid.

In addition to the above components, the maintenance liquid optionally contains a wetting agent (moisturizer), a surface tension adjusting agent (penetrating agent), a defoaming agent, a pH adjusting agent, an antioxidant, an antiseptic, and the like. Can be made to. Examples of these optional components include the components described in the above-mentioned water-based inkjet ink.

The viscosity of the maintenance liquid is preferably 1 to 200 mPa · s at 23 ° C., more preferably 3 to 100 mPa · s.
The pH of the maintenance liquid is preferably 5.5 to 9.0. Within this range, it is possible to suppress the generation of agglomerates in cleaning the head surface, prevent nozzle clogging, and improve continuous ejection performance.
The surface tension of the maintenance liquid is preferably 20 to 50 mN / m, more preferably 25 to 40 mN / m.
The method for producing the maintenance liquid is not particularly limited, but a desired maintenance liquid can be obtained by appropriately mixing each component. Further, the obtained composition may be filtered using a filter or the like.

Hereinafter, an example of a method of executing the maintenance operation using the ink set according to the embodiment will be described.
In the inkjet printing apparatus, maintenance operations of the inkjet head can be performed in order to reduce defective ink ejection from the inkjet head.
As one of the maintenance operations, a method of applying the maintenance liquid to the nozzle surface, a method of applying the maintenance liquid to the nozzle surface and wiping the nozzle surface with a wiper, and a method of wiping the nozzle surface with the wiper with the maintenance liquid applied to the wiper. There are methods and so on. In either method, according to one embodiment, the stability of the mixture liquid of the ink and the maintenance liquid can be improved on the nozzle surface, and ink stains can be efficiently removed from the nozzle surface.
Since the wiper material comes into contact with the head, a material such as silicone rubber or fluororubber, which has elasticity rather than a hard material so as not to damage the nozzle, is suitable. Since the wiper frequently comes into contact with the maintenance liquid and ink, it is preferable that the wiper has durability that is not deformed by these liquids.

The timing of executing the maintenance operation may be immediately before, immediately after, or both of printing. Further, the timing of executing the maintenance operation may be the timing after printing a predetermined number of times, the timing when the dirt on the nozzle surface is detected by a sensor or the like, and the like.
For the maintenance operation, a maintenance mechanism such as a maintenance liquid accommodating portion and a wiper may be provided in the inkjet printing apparatus. Alternatively, when the nozzle surface becomes dirty, the dirt on the nozzle surface may be manually wiped off with a maintenance liquid, or the nozzle surface may be immersed in the maintenance liquid to dissolve and remove the ink. good.
The maintenance liquid is suitable for cleaning the nozzle surface, but can also be applied to other members such as the inside of the nozzle head, the transport path of the base material, the ink tank, and the housing.

Hereinafter, the present invention will be described in detail with reference to Examples. The present invention is not limited to the following examples. In the following description, "%" indicates "mass%" and "-" in the table indicates no addition, unless otherwise specified.

[Manufacturing Example A]
<Preparation of pigment dispersion>
Table 1 shows the formulation of the pigment dispersion.
Each ingredient was premixed according to the formulation shown in the table. Then, 300 g of the mixture was placed in a 500 mL PP (polypropylene) container, and zirconia beads having a diameter of Φ0.5 mm were added so that the total amount in the PP container was about 90% of the container. This PP container was set in a locking mill (manufactured by Seiwa Giken Co., Ltd.) and dispersed for 2 hours, and then the zirconia beads were separated from the dispersion liquid to obtain a pigment dispersion.

The components used are as follows.
Magenta pigment: "FASTOGEN SUPER MAGENTA RGT" manufactured by DIC Corporation.
Acrylic dispersant: "DISPERBYK-190" manufactured by BYK, 40% active ingredient.
pH adjuster: "TEA (triethanolamine)" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.
Preservative: "PROXEL XL2 (S)" manufactured by Lonza Japan Co., Ltd.

<Making ink>
Tables 2 to 5 show the ink formulations of Examples and Comparative Examples. In each table, the blending amount of the magenta pigment dispersion is shown by the total amount of the pigment dispersion. The blending amount of each resin emulsion is indicated by the total amount of the resin emulsion. The unit of the pigment content of the pigment dispersion and the solid content of the resin emulsion shown in the table is mass%. The solvent contained in the pigment dispersion and the resin emulsion in the table is mainly water.
Each component was mixed according to the formulation of the ink shown in each table, and then filtered through a membrane filter having a pore size of 3 μm to obtain an ink.

The components used are as follows.
(Component 1: Pigment dispersion)
Magenta dispersion: produced by the above procedure; 20% pigment content.

(Component 2: Urethane resin emulsion)
Polyester type aliphatic urethane resin (1): "Takelac W-6020" manufactured by Mitsui Chemicals, Inc., solid content 30.0%.
Polyester type aliphatic urethane resin (2): "Permarin UA-200" manufactured by Sanyo Chemical Industries, Ltd., solid content 30.0%.
Polyester type aliphatic urethane resin (3): "Takelac W-5661" manufactured by Mitsui Chemicals, Inc., solid content 35.0%.
Polyester type aromatic urethane resin: "NeoRez R-9404" manufactured by DSM, solid content 31.0%.
Polyester type aliphatic urethane resin: "ADEKA BONTITER HUX-370" manufactured by ADEKA Corporation, solid content 33.0%.
Polycarbonate type aliphatic urethane resin: "Ucoat UX-485" manufactured by Sanyo Chemical Industries, Ltd., solid content 40.0%.
All of the above urethane-based resin emulsions are anionic. The component (2a) in the table shows a polyether type aliphatic urethane resin emulsion, and the component (2b) shows a comparative urethane resin emulsion.

(Component 3: Acrylic resin emulsion)
Styrene-acrylic resin: "Mobile 966A" manufactured by Japan Coating Resin Co., Ltd., solid content 45.0%.
Acrylic resin: "Mobile 9760" manufactured by Japan Coating Resin Co., Ltd., solid content 19.5%.
All of the above acrylic resin emulsions are anionic.

(Component 4: Water-soluble organic solvent)
Glycerin, 1,3-propanediol, diethylene glycol, propylene glycol, and diethylene glycol monoethyl ether in the table are available from Fujifilm Wako Pure Chemical Industries, Ltd.

(Ingredient 5: Surfactant)
Acetylene glycol (HLB: 4.0): "Surfinol 420" manufactured by Nissin Chemical Industry Co., Ltd.
Acetylene glycol (HLB: 8.1): "Surfinol 440" manufactured by Nissin Chemical Industry Co., Ltd.
Acetylene glycol (HLB: 13.2): "Orfin E1010" manufactured by Nissin Chemical Industry Co., Ltd.
Acetylene glycol (HLB: 17.1): "Surfinol 485" manufactured by Nissin Chemical Industry Co., Ltd.
All of the above surfactants are acetylene glycol-based surfactants, are nonionic, and have 100% by mass of the active ingredient. The component (5a) in the table indicates a surfactant having an HLB value of 10.0 or less, and the component (5b) indicates a surfactant having an HLB value of more than 10.0.

The HLB value of the surfactant is a numerical value obtained from the molecular structure of the surfactant by the following formula (1) according to the Griffin method.
HLB value = 20 x (formula weight of hydrophilic part) / (molecular weight of surfactant) ... formula (1)

The swelling rate of the urethane resin emulsion was measured according to the following procedure.
In the combination of the urethane-based resin emulsion and the surfactant to be blended in the ink to be measured, the rate at which the urethane-based resin emulsion swells while the urethane-based resin emulsion is immersed in the surfactant was determined. When two kinds of surfactants were blended in the ink to be measured, the mass ratio of the two kinds of surfactants was mixed with the blending ratio in the ink and used.
Put the urethane-based resin emulsion contained in the ink to be measured into a glass petri dish with a diameter of 5 cm in an amount that makes the solid content 1.5 g, and put it in a heat dryer at 100 ° C. to evaporate the water and dry the resin. A dry film was obtained. Cut the test piece into a dry film into a size of 1 cm x 1 cm, measure the mass, put it in a glass bottle, add 1.0 g of the surfactant contained in the ink to be measured, and immerse the dry film in it. After 12 hours, the surface of the dry film was taken out and the surfactant was wiped off, and then the mass was measured. The swelling rate was calculated from the following formula.
Swelling rate [%] = {((mass of dry film after immersion)-(mass of dry film before immersion)) / (mass of dry film before immersion)} × 100

<Evaluation method>
Using the obtained ink, a decorative article was prepared according to the following procedure, and the following evaluation was performed. The results are also shown in Tables 2 and 5.
A white-painted aluminum plate (Nikkar Shoko Co., Ltd., aluminum flat plate) was used as the base material.
A white-painted aluminum plate cut into 10 cm × 10 cm was heated in an oven at 70 ° C. for 10 minutes.
Each ink was introduced into the inkjet head of an inkjet printer (Anaget mPower-10 manufactured by Anaget), and a photographic image was printed in a single color of magenta in a state where the surface temperature of the heated white-painted aluminum plate was 40 ° C.
After printing, it was heated and dried in an oven at 150 ° C. for 10 minutes, and the obtained printed matter was used as a decorative article.

(Durability of printed images)
The image portion of the obtained decorative article was reciprocated with steel wool having a bottom area of 9 cm × 9 cm under a ^{load of 60 kg / m 2, and changes in the surface of the base material were observed.} The durability of the printed image was evaluated according to the following criteria.
AA: There is no significant change in the image even after rubbing 30 times back and forth.
A: After rubbing back and forth 30 times, the image becomes slightly whitish.
B: The image is peeled off after 30 round trips or less.
C: The image is peeled off after 10 round trips or less.
D: The image is peeled off after one round trip.

(Processability of printed images)
The obtained decorative article was bent at 90 degrees with a bender, and the change in the image of the bent portion was observed. The processability of the printed image was evaluated based on the following criteria.
A: No whitening due to minute cracks in the image due to bending was observed.
B: No whitening was observed, but minute cracks visible with a magnifying glass were observed.
C: Whitening was observed.
D: Whitening was observed, and peeling occurred from the cracked portion of the image.

(Image quality of printed images)
The image portion of the obtained decorative article was observed with a zoom microscope, and the presence or absence of yellowing of the photographic image was observed. The image quality of the printed image was evaluated based on the following criteria.
A: No yellowing is seen in the color of the photographic image.
B: The color of the photographic image is slightly yellowish.
C: The yellowness of the photographic image is strong.

As shown in each table, the printed matter of each example was excellent in durability and processability of the printed image, and further, the image quality of the printed image was also good.
Throughout each example, even if the types of urethane resin (A), (meth) acrylic resin (B), surfactant (C), and pigment are different, each evaluation can be made by using the components of one embodiment. It was good.
Throughout each example, it can be seen that when the blending amount of the urethane resin (A) is 3% by mass or more, the durability and processability of the printed image, particularly the durability, is further improved.
Throughout each example, it can be seen that the durability and processability of the printed image are further improved when the swelling rate of the urethane resin used in the ink to be measured with respect to the surfactant is 10 to 100%.
Through Examples 3, 5 and 7, it can be seen that the surfactant (C) may be a combination of two types, or a surfactant (C) and another surfactant may be combined.

Through each comparative example, if at least one of the urethane resin (A), the (meth) acrylic resin (B), and the surfactant (C) is not contained, sufficient results may not be obtained. Understand.
In Comparative Example 1, a polyester-type aliphatic urethane resin was used, and the durability and processability of the printed image were lowered. Further, in Comparative Example 1, the image quality of the printed image was deteriorated due to the ester bond of the urethane resin.
In Comparative Example 2, a polycarbonate-type aliphatic urethane resin was used, and the processability of the printed image was lowered. It is considered that this is because the resin itself is hard but has insufficient flexibility due to the carbonate bond of the urethane resin.
In Comparative Example 3, a polyether type aromatic urethane resin was used, and the durability and processability of the printed image were lowered. Further, in Comparative Example 3, yellowing of the ink coating film occurred due to the aromatic urethane bond of the urethane-based resin, and the image quality of the printed image deteriorated.
Comparative Example 4 is an example in which the (meth) acrylic resin is not used, and the image quality is not deteriorated due to the ink coating film, but the durability and processability of the printed image are deteriorated.

Comparative Examples 5 to 7 are examples in which the (meth) acrylic resin (B) is not used as compared with Comparative Examples 1 to 3, and the durability of the printed image is further lowered.
Comparative Example 8 is an example in which the urethane resin is not used, and the durability and processability of the printed image, particularly the processability, are deteriorated.
Comparative Examples 9 and 10 are examples in which a surfactant having an HLB value of more than 10.0 is used, and the durability and processability of the printed image are lowered. It is considered that this is partly because the homogeneity of the ink coating film is lowered because the interaction between the urethane resin (A) and the surfactant (C) having an HLB value of 10.0 or less cannot be obtained. Be done.
Throughout each comparative example, when the swelling rate of the urethane resin used in the ink to be measured with respect to the surfactant is less than 10%, it is considered that the durability and processability of the printed image are deteriorated from this point as well.

[Manufacturing Example B]
<Preparation of pigment dispersion>
A magenta pigment dispersion was prepared by the same procedure as in Production Example A.

<Making ink>
Table 6 shows the ink formulations. In each table, the blending amount of the magenta pigment dispersion is shown by the total amount of the pigment dispersion. The blending amount of each resin emulsion is indicated by the total amount of the resin emulsion. The unit of the pigment content of the pigment dispersion and the solid content of the resin emulsion shown in the table is mass%. The solvent contained in the pigment dispersion and the resin emulsion in the table is mainly water.
Each component was mixed according to the formulation of the ink shown in the table, and then filtered through a membrane filter having a pore size of 3 μm to obtain an ink.
The components used are common to the ink of Production Example A described above. The HLB value of the surfactant and the swelling rate of the urethane-based resin emulsion were determined in the same manner as in Production Example A described above.

<Preparation of maintenance liquid>
Table 7 shows the prescription of the maintenance liquid. Each component was mixed according to the formulation of the maintenance liquid shown in the table, and then filtered through a membrane filter having a pore size of 3 μm to obtain a maintenance liquid. The pH of the obtained maintenance liquid was measured and shown in the table.
The water-soluble organic solvents used are all available from Fujifilm Wako Pure Chemical Industries, Ltd. The surfactant and preservative used are the same as the ink of Production Example A described above.

<Evaluation method>
Using the obtained ink, a decorative article was prepared according to the same procedure as in Production Example A, and the following evaluation was performed. In the following evaluation of the uniformity and continuous ejection property of the printed image, the decorative article of the solid image is produced by repeating the same operation as in Production Example A except that the solid image is printed instead of the photographic image in a single color of magenta. did.
The durability of the printed image, the processability of the printed image, and the image quality of the printed image were evaluated according to the same procedure as in Production Example A described above.

The uniformity and continuous ejection property of the printed image were evaluated by combining the ink and the maintenance liquid as shown in Table 8.
(Uniformity of printed image)
After printing three borderless solid images on a 10 cm × 10 cm aluminum plate, the nozzle surface of the inkjet head was wiped off with a rubber blade soaked in each maintenance liquid. In this state, a solid image without a border was printed again on a 10 cm × 10 cm aluminum plate. The image portion of the decorative article obtained by printing after wiping the nozzle surface was observed with a zoom microscope, and the uniformity of the solid image was observed. The uniformity of the printed image was evaluated according to the following criteria.
A: A uniform solid image is formed.
B: There is unevenness in a part of the solid image.
C: There is unevenness in about half of the solid image.

(Continuous discharge)
After continuing to print 10 borderless solid images on a 10 cm × 10 cm aluminum plate, the nozzle surface of the inkjet head was wiped off with a rubber blade soaked in each maintenance liquid. In this state, after printing 10 borderless solid images on a 10 cm × 10 cm aluminum plate again, a nozzle check pattern was printed to check how many nozzles were not ejected. The continuous discharge property was evaluated according to the following criteria.
AA: The number of missing lines is 0.
A: The number of missing lines is 1 or more and 2 or less.
B: The number of missing lines is 3 or more and 4 or less.
C: The number of missing lines is 5 or more.

As shown in each table, the decorative article of each example was excellent in durability and processability of the printed image, and further, the image quality of the printed image was also good. Further, in the treatment using the maintenance liquid of each example, the uniformity and continuous ejection property of the printed image were good in the subsequent printing.

Inks B1 to B3 were used in Examples B1 to B6, and the durability, processability, and imageability of the printed image were good.

In Examples B1 to B3, the HLB value of the surfactant contained in the maintenance liquid was 8.1, and the uniformity of the printed image and the continuous ejection property were good. In Examples B1 to B3, since the ink and the maintenance liquid contained the same surfactant, the continuous ejection property was better.
In Example B4, the HLB value of the surfactant contained in the maintenance liquid was 4.0, and the uniformity of the printed image and the continuous ejection property were good.
In Example B5, the HLB value of the surfactant contained in the maintenance liquid is 13.2, and the uniformity and continuous ejection property of the printed image are deteriorated.
In Example B6, the HLB value of the surfactant contained in the maintenance liquid is 17.1, and the uniformity and continuous ejection property of the printed image are deteriorated.
Through Examples B1 to B6, the ink adhering to the nozzle surface of the nozzle head is appropriately removed within the range where the HLB value of the surfactant contained in the maintenance liquid is 10.0 or less, and the uniformity of the printed image and continuous ejection are achieved. It is thought that the sex will be improved.

Claims (6)

Water-dispersible polyether type aliphatic urethane resin (A), water-dispersible (meth) acrylic resin (B), acetylene glycol-based surfactant (C) having an HLB value of 10.0 or less, coloring material, And water-based inkjet inks, including water. The water-dispersible polyether-type aliphatic urethane resin (A) is prepared by using a test piece obtained by using the water-dispersible polyether-type aliphatic urethane resin (A) as a dry film as a surfactant to be blended in ink. The water-based inkjet ink according to claim 1, wherein the mass-based swelling rate from before immersion is 10% or more and 100% or less when the ink is immersed and taken out 12 hours later. The water-based inkjet ink according to claim 1 or 2, wherein the water-dispersible polyether type aliphatic urethane resin (A) is 3.0% by mass or more based on the total amount of the ink. The water-based inkjet ink according to any one of claims 1 to 3 and
An ink set containing an acetylene glycol-based surfactant (C') having an HLB value of 10.0 or less and a maintenance liquid containing glycerin having an HLB value of 30% by mass or more based on the total amount of the maintenance liquid. The ink set according to claim 4, wherein the maintenance liquid has a water content of 40 to 60% by mass with respect to the total amount of the maintenance liquid. The acetylene glycol-based surfactant (C) contained in the water-based inkjet ink and
The ink set according to claim 4 or 5, wherein the acetylene glycol-based surfactant (C') contained in the maintenance liquid contains the same component.