JP7835540B2 - Method of manufacturing printed materials - Google Patents

Description

This invention relates to a method for producing printed materials.

In addition to screen printing and roller printing, methods for printing images such as letters, pictures, and patterns onto fabrics such as woven, knitted, and nonwoven materials have recently attracted attention. These methods utilize computer-aided image processing to enable printing with virtually no printing plates.
Pigments and dyes are examples of colorants used in inks for textile printing. Dye inks have the advantage of good color development and high colorfastness. However, dye inks have problems such as requiring the selection of dye type according to the type of fabric fiber, requiring a washing process to remove unfixed dye after printing, and having lower lightfastness compared to pigment inks.
Pigment inks can impart pigment to fabrics regardless of the fabric's fiber type, generally eliminate the need for post-printing cleaning, and offer good lightfastness. However, because pigment inks have weak bonding strength between the fabric and the pigment, one method involves adding a binder resin to the pigment ink to form an ink film on the fabric surface, thereby fixing the pigment to the fabric. When using inkjet printing to eject ink and obtain printed materials, the amount of binder resin added to the water-based ink is limited from the standpoint of ink viscosity and ink ejection performance, resulting in problems with achieving sufficient colorfastness.

To achieve good colorfastness for pigment inks, one method involves applying an undercoat liquid to the fabric before printing the pigment ink. Patent Document 1 proposes a printing method for inkjet printing with digital inks, in which an aqueous pigment ink containing pigment, water, a crosslinking agent, and a polymer is printed onto fabric that has been pre-treated with an aqueous solution containing an organic acid.

Patent Document 2 describes an inkjet printing method in which an aqueous pigment ink containing a pigment, an aqueous liquid, a crosslinking-reactive water-soluble dispersant, a self-emulsifying urethane resin, and a blocked isocyanate compound is printed onto a fabric-like fiber product that has been pretreated with a quaternary ammonium salt type cationic surfactant and a blocked isocyanate compound. The method proposes that, on the fabric-like fiber product, the blocked isocyanate compound applied in the pretreatment and the blocked isocyanate compound in the aqueous pigment ink are crosslinked with the crosslinking-reactive water-soluble dispersant and the self-emulsifying urethane resin in the aqueous pigment ink, thereby firmly fixing the pigment to the fibers.

U.S. Patent No. 8,926,080 Japanese Patent Publication No. 2014-129617

In Patent Documents 1 and 2, the ink contains a highly reactive resin and components such as crosslinking agents that can react with the resin. This can lead to deterioration of the ink over time, resulting in increased viscosity or the generation of foreign matter, reduced ink stability, and insufficient ejection performance suitable for inkjet inks.

One objective of the present invention is to provide a method for manufacturing printed textiles that exhibits excellent ink stability and superior image quality and colorfastness.

One aspect of the present invention is a method for manufacturing a printed fabric, comprising: a first step of applying an undercoat liquid containing a crosslinking agent (B) and water, but not containing a resin that reacts with the crosslinking agent, to a fabric by an inkjet recording method; a second step of applying an aqueous ink containing a urethane resin (A), a pigment, and water, but not containing a crosslinking agent, to the fabric by an inkjet recording method; and a third step of heating the fabric to which the aqueous ink has been applied, wherein the method satisfies the following formula 1.
0.1 ≤ Amount of crosslinking agent (B) contained in the undercoat liquid / Amount of urethane resin (A) contained in the aqueous ink ≤ 5.0 (1)
In Equation 1, the amount of urethane resin (A) and the amount of crosslinking agent (B) applied represent the mass per unit area of the region where the aqueous ink and undercoat liquid are applied in layers.

According to one embodiment of the present invention, it is possible to provide a method for manufacturing printed materials that exhibits excellent ink stability and superior image quality and fastness of the printed materials.

The present invention will be described below using one embodiment. The examples in the following embodiment do not limit the present invention.

A method for manufacturing a printed fabric according to one embodiment comprises a first step of applying an undercoat liquid containing a crosslinking agent (B) and water, but without a resin that reacts with the crosslinking agent, to a cloth by an inkjet recording method; a second step of applying an aqueous ink containing a urethane resin (A), a pigment, and water, but without a crosslinking agent, to the cloth by an inkjet recording method; and a third step of heating the cloth to which the aqueous ink has been applied, and is characterized by satisfying the following formula 1.
0.1 ≤ Amount of crosslinking agent (B) in the undercoat liquid / Amount of urethane resin (A) in the water-based ink ≤ 5.0 (1)
In Equation 1, the amount of urethane resin (A) and the amount of crosslinking agent (B) applied represent the mass per unit area of the region where the aqueous ink and undercoat liquid are applied in layers.
According to this, it is possible to provide a method for manufacturing printed materials that has excellent ink stability and excellent image quality and fastness of the printed materials.

In one embodiment, as can be seen from Equation 1, the fastness of the printed material can be improved by using a crosslinking agent amount of 10% by mass or more of the urethane resin. Generally, the amount of crosslinking agent used is around 5% by mass of the urethane resin. However, in this embodiment, the crosslinking agent (B) contained in the undercoat liquid and the urethane resin (A) contained in the water-based ink are reacted on the fabric surface, so this does not match the general ratio.

The water-based ink contains urethane resin (A) but no crosslinking agent, and the undercoat liquid contains crosslinking agent (B) but no resin that reacts with the crosslinking agent. This allows both the water-based ink and the undercoat liquid to be less susceptible to deterioration over time, providing excellent stability. Although the water-based ink contains urethane resin (A), the absence of a crosslinking agent prevents the crosslinking reaction of urethane resin (A) within the water-based ink, preventing thickening and aggregation of the ink, thus enhancing its stability. The low viscosity and low amount of aggregates in the water-based ink further improve ink ejection performance from the inkjet nozzle.

"Undercoat liquid"
The undercoat liquid preferably contains a crosslinking agent (B) and water, and does not contain a resin that reacts with the crosslinking agent.
The undercoat liquid preferably contains a crosslinking agent (B). This crosslinking agent (B) reacts with the urethane resin (A) contained in the water-based ink on the fabric surface, forming a crosslinked structure that can further improve the durability of the urethane resin coating.
It is preferable that the undercoat liquid does not contain a resin that reacts with the crosslinking agent. If the undercoat liquid contains both the crosslinking agent (B) and a resin that reacts with the crosslinking agent, a crosslinking reaction may occur in the undercoat liquid, increasing its viscosity or causing the generation of foreign matter, which can lead to a decrease in discharge performance. When the undercoat liquid does not contain a resin that reacts with the crosslinking agent, the increase in viscosity and the generation of foreign matter are prevented, and discharge performance can be further improved.

A resin that reacts with a crosslinking agent is a resin that has crosslinking reactive groups that can react with the crosslinking agent. Examples of crosslinking reactive groups include carboxyl groups, hydroxyl groups, amino groups, amide bonds, epoxy groups, phosphate groups, and sulfo groups (silanol groups, silane groups).
The resin that reacts with the crosslinking agent is preferably limited to 0.5% by mass or 0.1% by mass or less relative to the total amount of the undercoat liquid, and preferably is substantially absent. Specifically, the resin that reacts with the crosslinking agent (B) contained in the undercoat liquid is preferably limited to 0.5% by mass or 0.1% by mass or less relative to the total amount of the undercoat liquid, and preferably is substantially absent.
In particular, it is preferable that the undercoat liquid does not contain urethane resin as the resin that reacts with the crosslinking agent. In the undercoat liquid, the amount of urethane resin is preferably limited to 0.5% by mass or less, or 0.1% by mass or less, and preferably substantially absent. In particular, it is preferable that the content of urethane resin (A) contained in the water-based ink be limited within this range.

The undercoat liquid preferably does not contain a resin that reacts with the crosslinking agent, and more preferably does not contain a binder resin. The binder resin is a resin component capable of forming a coating film on the fabric surface.
If a resin coating is formed on the fabric surface before the water-based ink is applied, the water-based ink will have difficulty penetrating the fabric fibers, which can reduce the anchoring effect and decrease the colorfastness. Therefore, the resin component, including the binder resin, may be 0.5% by mass or less, or 0.1% by mass or less, of the total amount of the undercoat liquid, including the resin that reacts with the crosslinking agent mentioned above, and may not be substantially present. Specifically, it is preferable that the undercoat liquid does not contain the binder resin described later in the section on water-based inks as a resin component.

The undercoat liquid may contain a crosslinking agent (B). Preferably, the crosslinking agent (B) is a crosslinking agent that is reactive with the urethane resin. Such a crosslinking agent (B) reacts with the urethane resin (A) when the undercoat liquid and aqueous ink are applied to the fabric surface, forming a crosslinked structure and further increasing the strength of the coating film.
The crosslinking agent (B) can be a water-soluble crosslinking agent, a water-dispersible crosslinking agent, a water-insoluble crosslinking agent, etc., with a water-soluble crosslinking agent being more preferable. It is preferable that the crosslinking agent (B) is a water-soluble crosslinking agent. Because a water-soluble crosslinking agent dissolves in water, it can be blended more uniformly in the undercoat liquid, and as a result, the water-soluble crosslinking agent can be applied more uniformly to the fabric surface. By applying water-based ink to a fabric to which the water-soluble crosslinking agent has been uniformly applied, the crosslinking reaction with the urethane resin (A) can be advanced more uniformly.
The water-soluble crosslinking agent may be a crosslinking agent that dissolves at a concentration of 1 g or more per 100 g of water at 23°C. Preferably, the water-soluble crosslinking agent dissolves at a concentration of 5 g or more, 8 g or more, or 10 g or more per 100 g of water at 23°C.

Examples of crosslinking agents (B) include carbodiimide compounds, aziridine compounds, oxazoline compounds, metal chelate compounds, epoxy compounds, isocyanate compounds, melamine compounds, urea compounds, polyamine compounds, polyethyleneimine compounds, acrylamide compounds, and the like. These can be used individually or in combination of two or more.
As the crosslinking agent (B), from the viewpoint of crosslinking reactivity with the urethane resin (A) on the fabric surface, carbodiimide compounds, aziridine compounds, oxazoline compounds, metal chelate compounds, epoxy compounds, isocyanate compounds, or combinations thereof are preferred, carbodiimide compounds, aziridine compounds, oxazoline compounds, or combinations thereof are more preferred, and carbodiimide compounds are even more preferred.

The carbodiimide compound is a compound having a carbodiimide group represented as "-N=C=N-" in its molecule, and polycarbodiimides are preferred. More preferably, it is a water-soluble compound having a carbodiimide group, and even more preferably, it is a water-soluble polycarbodiimide.
Commercially available carbodiimide compounds include, for example, the CarbodiLite series manufactured by Nisshin Fat Chemical Co., Ltd., such as "V-02,""SV-02,""V-04K,""V-10," and "SW-12G" (all are trade names).

As aziridine compounds, it is preferable to use compounds having aziridine groups in the molecule, and more preferably polyfunctional aziridine compounds having two or more aziridine groups in the molecule.
Commercially available aziridine compounds include, for example, "PZ-33" from the Chemitight series manufactured by Nippon Shokubai Co., Ltd.

As for oxazoline compounds, polymers having an oxazoline group are preferred. As for polymers having an oxazoline group, those obtained by polymerizing monomer components containing an addition-polymerizable oxazoline as an essential component are preferred.

Commercially available oxazoline compounds include, for example, "Epocross WS-300, 500, and 700" manufactured by Nippon Shokubai Co., Ltd.

As metal chelate compounds, chelate compounds using metallic elements such as titanium, aluminum, iron, copper, zinc, tin, nickel, antimony, magnesium, vanadium, chromium, and zirconium can be used.
As a commercially available metal chelating compound, for example, "TC-400" from the Orgatics series manufactured by Matsumoto Fine Chemical Co., Ltd. can be used.

Examples of epoxy compounds include monofunctional epoxy compounds, difunctional epoxy compounds, and polyfunctional epoxy compounds, with polyfunctional epoxy compounds incorporating hydrophilic groups being preferred.

The crosslinking agent (B) may be 1% by mass or more, 5% by mass or more, or 10% by mass or more, relative to the total amount of the undercoat liquid. This ensures a sufficient amount of undercoat liquid is applied to the fabric, thereby further promoting the crosslinking reaction with the urethane resin (A) on the fabric surface.
The crosslinking agent (B) may be 25% by mass or less, 20% by mass or less, or 15% by mass or less, based on the total amount of the undercoat liquid. This maintains solubility in the undercoat liquid and further improves the storage stability of the undercoat liquid.
For example, the crosslinking agent (B) may be 1 to 35% by mass, 5 to 20% by mass, or 10 to 15% by mass, relative to the total amount of the undercoat liquid.

The undercoat liquid may contain water, which may be tap water, deionized water, distilled water, ultrapure water, deionized water, etc. The amount of water may be 10 to 99% by mass, or 20 to 95% by mass, relative to the total volume of the undercoat liquid. It is preferable that the undercoat liquid contains water as its main component, and the amount of water may be 50% or more by mass, 70% or more by mass, or 80% or more by mass, relative to the total volume of the undercoat liquid.

The undercoat liquid may further contain a water-soluble organic solvent. The amount of the water-soluble organic solvent may be 1 to 50% by mass, 5 to 30% by mass, or 10 to 20% by mass, relative to the total volume of the undercoat liquid. Specific examples of water-soluble organic solvents can be those described later in the section on water-based inks.

The undercoat liquid may further contain a surfactant. The inclusion of a surfactant in the undercoat liquid improves its affinity to the fabric or ink film, thereby further improving the coating properties of the undercoat liquid. Specific examples of surfactants include those described later in the section on water-based inks. Among these, nonionic surfactants are preferred, and more specifically, silicone-based surfactants, acetylene glycol-based surfactants, or combinations thereof are preferred.
The surfactant may be present in an amount of active ingredient of 0.01 to 10% by mass, 0.05 to 5% by mass, or 0.1 to 1% by mass, relative to the total amount of the undercoat liquid.

In addition to the above components, the undercoat liquid may optionally contain wetting agents (moisturizers), surface tension modifiers (penetrating agents), defoamers, fixing agents, pH adjusters, antioxidants, preservatives, etc.

The viscosity of the undercoat liquid can be adjusted as appropriate, but for example, from the viewpoint of ejection performance, a viscosity of 1 to 30 mPa·s at 23°C is preferable. The viscosity of the undercoat liquid can be measured using a rotational viscometer. Undercoat liquids within this viscosity range can be suitably used in any inkjet recording method, such as piezo, electrostatic, or thermal methods.

The method for producing the undercoat liquid is not particularly limited, but for example, the undercoat liquid can be obtained by dispersing or dissolving a crosslinking agent (B) and, if necessary, other components in water.

"Water-based ink"
Water-based ink preferably contains a urethane resin (A), a pigment, and water, and does not contain a crosslinking agent.
The water-based ink preferably contains a urethane resin (A).
The urethane resin (A) is a resin that possesses crosslinking reactivity and can react with a crosslinking agent to form a crosslinked structure. On the surface of the fabric, the urethane resin (A) forms a crosslinked structure to become a coating film, thereby increasing its durability. For this purpose, a coating film of urethane resin (A) is formed on a fabric that has been treated with an undercoat liquid containing a crosslinking agent, using a water-based ink, thereby promoting the crosslinking reaction of the urethane resin (A) on the fabric surface.

Water-based inks preferably do not contain crosslinking agents. When a water-based ink contains a crosslinking agent along with the urethane resin (A), the urethane resin (A) and the crosslinking agent react in the water-based ink to form a crosslinked structure, which can increase the ink viscosity or cause foreign matter to be generated in the ink, potentially leading to a decrease in ejection performance. When a water-based ink does not contain a crosslinking agent, the increase in ink viscosity and the generation of foreign matter are suppressed, and ejection performance can be further improved.
For example, in water-based inks, the amount of crosslinking agent is often limited to 0.5% by mass or 0.1% by mass or less of the total amount of ink, and may be substantially omitted.

More specifically, it is preferable that the aqueous ink does not contain water-soluble crosslinking agents, water-dispersible crosslinking agents, water-insoluble crosslinking agents, or combinations thereof. In particular, it is preferable that water-soluble crosslinking agents are not included in the aqueous ink because they react with the urethane resin (A) in the aqueous medium to form a crosslinked structure. The amount of water-soluble crosslinking agent is preferably limited to 0.5% by mass or less, or 0.1% by mass or less, of the total amount of ink, and may be substantially absent.
More specifically, it is preferable that the water-based ink does not contain a water-soluble crosslinking agent that reacts with the urethane resin (A). For example, it is preferable that it does not contain the crosslinking agent (B) described in the undercoat liquid above.

The urethane resin (A) may be a water-soluble urethane resin, a water-dispersible urethane resin, or a combination thereof, with a water-dispersible urethane resin being more preferred.
Urethane resin (A) adheres easily to fabric, forming a coating on the fabric surface and improving the fixation of ink images. Water-dispersible urethane resin can further improve the fixation of ink images and enhance the fastness of printed materials.
From the viewpoint of dispersion stability in water-based inks, water-dispersible urethane resins are preferably incorporated into water-based inks in the form of a water-based resin emulsion (O/W type emulsion).

The average particle size of the water-dispersible urethane resin should be appropriately selected according to the size of the gaps in the fabric, but from the viewpoint of inkjet ejection performance, 0.01 to 0.50 μm is preferred, and 0.05 to 0.30 μm is more preferred. In this specification, the average resin particle size of the water-dispersible resin refers to the volume-based cumulative 50% average particle size (d50) measured by light scattering (Nanoticarc particle size distribution analyzer manufactured by Nikkiso Co., Ltd.).

The urethane resin (B) may be either an aliphatic urethane resin or an aromatic urethane resin, and may be any of the following: polyester-based urethane resin, polyether-based urethane resin, polyester/polyether-based urethane resin, or polycarbonate-based urethane resin. These may be appropriately selected from the viewpoint of coating strength and flexibility depending on the intended use of the printed material, and one or more types may be used in combination.

The water-dispersible urethane resin is not particularly limited as long as it has a urethane skeleton and is water-dispersible. Among these, anionic urethane resins having anionic functional groups such as carboxyl groups, sulfo groups, and hydroxyl groups are preferred. The anionic functional groups introduced into the urethane resin can act as crosslinking reactive groups.
Specific examples of water-dispersible urethane resins that satisfy the above characteristics include anionic resins having a urethane skeleton, specifically "Superflex 150, Superflex 300, Superflex 460, Superflex 470, Superflex 740, Superflex 840" etc. from Daiichi Kogyo Seiyaku Co., Ltd., "Takelac WS-6021, Takelac W-512-A-6, Takelac W-6110" etc. from Mitsui Chemicals Polyurethane Co., Ltd., "Adeka Bontiter HUX-370, Adeka Bontiter HUX-380" etc. from Adeka Corporation, and "NeoRez R-9660, NeoRez R-966, NeoRez R-986, NeoRez R-2170" etc. from DSM Corporation (all are product names).

The urethane resin (A) may be present in an amount of 1% by mass or more, 3% by mass or more, or 5% by mass or more, relative to the total amount of water-based ink. This allows for the formation of an appropriate coating film on the fabric surface, further improving adhesion and durability. From the viewpoint of coating film strength, the content should be 5% by mass or more, 8% by mass or more, or 10% by mass or more.
The urethane resin (A) may be present in amounts of 30% by mass or less, 20% by mass or less, or 15% by mass or less, relative to the total amount of the water-based ink. This allows for the formation of an appropriate amount of coating film on the fabric surface while maintaining dispersion stability in the ink.
For example, the urethane resin (A) may be 1 to 30% by mass, 3 to 20% by mass, or 5 to 15% by mass, relative to the total amount of the aqueous ink.

The undercoat liquid may contain binder resins other than urethane resin (A).
Other binder resins may be water-soluble resins, water-dispersible resins, or combinations thereof. As other binder resins, anionic water-dispersible resins can be used in combination with urethane resin (A) to improve adhesion and fastness.

Other water-dispersible resins used as binder resins include, for example, conjugated diene resins such as styrene-butadiene copolymers and methyl methacrylate-butadiene copolymers; acrylic resins such as polymers or copolymers of acrylic acid esters, methacrylic acid esters, or combinations thereof, or copolymers of these with styrene, etc.; vinyl resins such as vinyl chloride-vinyl acetate copolymers and ethylene-vinyl acetate copolymers; functional group-modified resins using monomers containing functional groups such as carboxyl groups of these various resins; melamine resins, urea resins, polyester resins, polyolefin resins, silicone resins, polyvinyl butyral resins, alkyd resins, etc. These water-dispersible resins may be used individually or in combination of two or more. These water-dispersible resins may also be in the form of aqueous resin emulsions (O/W type emulsions). The aqueous resin emulsion may be a resin emulsion of one of the above resins, or a hybrid type resin emulsion consisting of two or more of the above resins.
Among these, polyolefin resins, acrylic resins, or combinations thereof are preferred from the viewpoint of ink fixation, with polyolefin resins being more preferred.
The average particle size of the water-dispersible resin other than urethane resin (A) is preferably 0.01 to 0.50 μm, and more preferably 0.05 to 0.30 μm.

Examples of commercially available water-dispersible polyolefin resins include the Arrowbase series from Unitika Ltd. ("Arrowbase SB-1010," "Arrowbase SE-1010," "Arrowbase DC1010," etc.), the Hardlen series from Toyobo Co., Ltd. ("NZ1004," "EW5250," "EH801J," etc.), and the AQUACER series from Big Chemie Co., Ltd. ("272," "497," "515," "531," "537," etc.) (all are product names).

Examples of water-dispersible acrylic resins include water-dispersible styrene (meth)acrylic resin and water-dispersible (meth)acrylic resin. Both styrene (meth)acrylic resin and water-dispersible (meth)acrylic resin are not particularly limited, and commercially available products can be used.
Examples of commercially available water-dispersible styrene (meth)acrylic resins or water-dispersible (meth)acrylic resins include "Movinyl 966A, Movinyl 6750, Movinyl 6751D, Movinyl 6960, Movinyl 6718, Movinyl 7320" from Nippon Synthetic Chemical Co., Ltd., "Microgel E-1002, Microgel E-5002" from Nippon Paint Co., Ltd., "Boncoat 4001, Boncoat 5454" from DIC Corporation, "SAE1014" from Nippon Zeon Co., Ltd., "Saibinol SK-200" from Saiden Chemical Co., Ltd., "Neocryl BT-62, Neocryl SA-1094" from DSM, and "Joncryl 7100, Joncryl 390, Joncryl 711, Joncryl 511, Joncryl 7001, Joncryl 632, Joncryl 741, Joncryl" from BASF. 450, Joncryl 840, Joncryl 74J, Joncryl HRC-1645J, Joncryl 734, Joncryl 852, Joncryl 7600, Joncryl 775, Joncryl 537J, Joncryl 1535, Joncryl PDX-7630A, Joncryl 352J, Joncryl 352D, Joncryl PDX-7145, Joncryl 538J, Joncryl 7640, Examples include "Joncryl 7641, Joncryl 631, Joncryl 790, Joncryl 780, Joncryl 7610", "Vinibran 2580, Vinibran 2585, Vinibran 2682, Vinibran 2680, Vinibran 2684, Vinibran 2685, Vinibran 2687" manufactured by Nisshin Chemical Industry Co., Ltd., and "NK Binder R-5HN" manufactured by Shin Nakamura Chemical Industry Co., Ltd. (all are product names).

The resin content in the water-based ink may be 1 to 30% by mass, 5 to 20% by mass, or 10 to 15% by mass of the total amount of water-based ink, as the total amount of urethane resin (A) and other resins. The mass ratio of urethane resin (A) to the total amount of urethane resin (A) and other resins may be 50% by mass or more, 60% by mass or more, or 80% by mass or more.

Water-based inks may contain pigments. The pigment is preferably present in an amount of 0.01 to 20% by mass, 0.1 to 10% by mass, or 1 to 5% by mass relative to the total amount of ink.

Examples of pigments include azo, polycyclic, nitro, and nitroso organic pigments (such as Brilliant Carmine 6B, Lake Red C, Watching Red, Disazo Yellow, Phthalocyanine Blue, Phthalocyanine Green, Alkali Blue, and Aniline Black), metals such as cobalt, iron, chromium, copper, zinc, lead, titanium, vanadium, manganese, and nickel, as well as metal oxides and sulfides, and inorganic pigments such as yellow ochre, ultramarine, and Prussian blue, and carbon blacks such as furnace carbon black, lamp black, acetylene black, and channel black.

Furthermore, as a pigment, a pigment dispersion can be used, which is obtained by dispersing a self-dispersible pigment, whose pigment surface has been modified with hydrophilic functional groups, in an aqueous solvent. Examples of commercially available pigment dispersions include the CAB-O-JET series from Cabot Corporation ("CAB-O-JET200, CAB-O-JET300, CAB-O-JET400, CAB-O-JET250C, CAB-O-JET450C, CAB-O-JET260M, CAB-O-JET465M, CAB-O-JET270") and the BONJET series from Orient Chemical Industries, Ltd. ("BONJET BLACK CW-1, BONJET BLACK CW-2, BONJET BLACK CW-3") (all are product names).
The pigments mentioned above may be used individually or in combination of two or more types.
To ensure stable dispersion of pigments in water, the ink may further contain a pigment dispersant.

Water-based ink may contain water, which may be tap water, deionized water, distilled water, ultrapure water, deionized water, etc. The amount of water may be 10 to 90% by mass, or 20 to 80% by mass, relative to the total amount of ink. Water-based ink preferably contains water as its main component, and the amount of water may be 50% or more by mass, 60% or more by mass, or 70% or more by mass, relative to the total amount of water-based ink.

Water-based inks may further contain water-soluble organic solvents.
As the water-soluble organic solvent, a compound that is liquid at room temperature (23°C) and soluble in water can be used, and it is preferable to use a water-soluble organic solvent that mixes uniformly with the same volume of water at 1 atmosphere and 20°C. For example, lower alcohols such as methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, 2-methyl-2-propanol, and 1,2-hexanediol; glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, and polypropylene glycol; glycerins such as glycerin, diglycerin, triglycerin, and polyglycerin; acetins such as monoacetin and diacetin; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, and ethylene glycol monobutyl ether. Glycol ethers such as 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, and tetraethylene glycol diethyl ether can be used; triethanolamine, 1-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, β-thiodiglycol, sulfolane, etc. The boiling point of the water-soluble organic solvent is preferably 100°C or higher, and more preferably 150°C or higher.

These water-soluble organic solvents can be used individually or in combination of two or more. The amount of water-soluble organic solvent may be 5-90% by mass, 10-50% by mass, or 10-30% by mass, relative to the total amount of ink.

Water-based inks can also contain surfactants.
Surfactants include ionic surfactants such as cationic surfactants, anionic surfactants, and amphoteric surfactants, as well as nonionic surfactants, but nonionic surfactants are preferred among them.

Furthermore, the surfactant may be either a low molecular weight surfactant or a high molecular weight surfactant (generally referring to those with a molecular weight of approximately 2000 or more). The HLB value of the surfactant is preferably 5 to 20, and more preferably 10 to 18.

Examples of nonionic surfactants include silicone-based surfactants, acetylene glycol-based surfactants, polyoxyethylene alkyl ether-based surfactants, polyoxypropylene alkyl ether-based surfactants, polyoxyethylene alkylphenyl ether-based surfactants, polyoxypropylene alkylphenyl ether-based surfactants, polyoxyethylene fatty acid ester-based surfactants, polyoxypropylene fatty acid ester-based surfactants, sorbitan fatty acid ester-based surfactants, polyoxyethylene sorbitan fatty acid ester-based surfactants, polyoxyethylene sorbitol fatty acid ester-based surfactants, and glycerin fatty acid ester-based surfactants. These may be used individually or in combination of two or more.

Among these, silicone-based surfactants, acetylene glycol-based surfactants, or combinations thereof are preferred.
Examples of commercially available silicone-based surfactants include "Sylface SAG014" (product name, manufactured by Nisshin Chemical Industry Co., Ltd.).
Examples of commercially available acetylene glycol-based surfactants include "Orphine E1010" and "Orphine E1020" (both product names, manufactured by Nisshin Chemical Industry Co., Ltd.), which are acetylene glycols.

The surfactant is preferably present in an amount of 0.1 to 5% by mass, and more preferably 0.2 to 2% by mass, relative to the total amount of ink.

In addition to the above components, water-based inks may optionally contain wetting agents (moisturizers), surface tension modifiers (penetrating agents), defoamers, fixatives, pH adjusters, antioxidants, preservatives, etc.

The viscosity of the water-based ink can be adjusted as appropriate, but for example, from the viewpoint of ejection performance, a viscosity of 1 to 30 mPa·s at 23°C is preferable. The viscosity of the ink can be measured using a rotational viscometer. Water-based inks within this viscosity range can be suitably used in any inkjet recording method, such as piezo, electrostatic, or thermal methods.

The method for manufacturing aqueous ink is not particularly limited, but for example, aqueous ink can be prepared by dispersing all components together or in separate portions in a disperser such as a bead mill, and then, if desired, passing it through a filter such as a membrane filter.

"Method of manufacturing printed materials"
The following describes in detail the method for manufacturing printed materials using the undercoat liquid and water-based ink described above.
One embodiment of the method for manufacturing a printed fabric includes applying an undercoat liquid to a cloth by an inkjet recording method, applying an aqueous ink to the cloth by an inkjet recording method, and heating the cloth to which the aqueous ink has been applied. The undercoat liquid and aqueous ink described above can be used.

In this method for producing printed materials, it is preferable that the following formula 1 is satisfied.
0.1 ≤ Amount of crosslinking agent (B) contained in the undercoat liquid / Amount of urethane resin (A) contained in the aqueous ink ≤ 5.0 (1)
In Equation 1, the amount of urethane resin (A) and the amount of crosslinking agent (B) applied represent the mass per unit area of the region where the undercoat liquid and water-based ink are applied in layers.
The amount of urethane resin (A) contained in the water-based ink is expressed as the amount of urethane resin (A) per unit area (g/ ^m² ). Urethane resin (A) is calculated in terms of resin content.
The amount of crosslinking agent (B) contained in the undercoat liquid is expressed as the amount of crosslinking agent (B) per unit area (g/ ^m² ). The amount of crosslinking agent (B) is calculated based on the active ingredient.
Hereinafter, the ratio of the amount of crosslinking agent (B) contained in the undercoat liquid to the amount of urethane resin (A) contained in the water-based ink may be abbreviated as "crosslinking agent (B) / urethane resin (A) ratio".

The ratio of the amount of crosslinking agent (B) to urethane resin (A) is preferably 0.1 or more, 1 or more, or 1.5 or more. Within this range, the urethane resin in the aqueous ink is applied to the crosslinking agent in the undercoat liquid applied to the fabric surface. As a result, a crosslinked structure is formed in the urethane resin coating on the fabric surface, which can further improve its durability.
The ratio of the amount of crosslinking agent (B) to urethane resin (A) is preferably 5.0 or less, 4.0 or less, or 3.0 or less. It is good to apply a sufficient amount of crosslinking agent to the fabric surface with the undercoat liquid to promote crosslinking of the urethane resin, but if the fabric fibers are altered by an excess of undercoat liquid, the water-based ink applied afterward may not adhere well to the fabric surface. Furthermore, by preventing the application of an excessive amount of crosslinking agent and reducing the amount of undercoat liquid itself applied, workability in the drying process and other steps can be further improved. Therefore, the application ratio is preferably within this range.

The following provides a detailed explanation of each step.
In the first step, the undercoat liquid can be applied to the fabric by inkjet recording. The undercoat liquid may contain a crosslinking agent (B) and water, and may not contain a resin that reacts with the crosslinking agent; further details are as described above.
The inkjet recording method is not particularly limited, and any method described later for water-based inks can be applied.

The amount of undercoat liquid applied to the fabric may be 1 to 200 g/ ^m² , 5 to 100 g/ ^m² , or 10 to 50 g/ ^m² . This range depends on the proportion of crosslinking agent (B) contained in the undercoat liquid, but it is within the range in which the crosslinking agent (B) contained in the undercoat liquid can be applied to the fabric in an appropriate amount.
When the undercoat liquid is applied to the fabric, the amount of crosslinking agent (B) applied to the fabric may be 0.1 to 20 g/ ^m² , 0.5 to 10 g/ ^m² , or 1 to 5 g/ ^m² in terms of the amount of active ingredient.

The undercoat liquid is preferably applied to the image area where the water-based ink is to be applied. For example, the undercoat liquid may be applied to an area that roughly coincides with the image area covered by the water-based ink, a wider area including the image area covered by the water-based ink, or a wide area within a certain region including the image area covered by the water-based ink.

The cloth coated with the undercoat liquid may be used directly in the second step, dried at room temperature to remove moisture before being used in the second step, or heated to remove moisture before being used in the second step. Preferably, the step of heating the cloth coated with the undercoat liquid should be included before the second step.

By heating a fabric coated with an undercoat solution and then applying water-based ink to the fabric, the colorfastness of the printed material can be improved. While the exact mechanism is unclear, it is presumed that the heating step after applying the undercoat solution and before the water-based ink removes moisture from the fabric surface, allowing the crosslinking agent in the undercoat solution to remain on the surface. The subsequent application of water-based ink then promotes the crosslinking reaction between the crosslinking agent and the urethane resin (A) in the water-based ink on the fabric surface, thereby improving the colorfastness of the printed material.

By heating a cloth coated with an undercoat solution and then applying water-based ink to the cloth, the image density of the printed material can be increased. While the exact mechanism is not fully understood, it is thought that, similar to the above, the removal of water from the undercoat solution before the application of water-based ink allows the crosslinking agent to remain on the cloth surface. This crosslinking agent inhibits the penetration of the water-based ink, allowing the pigment to remain on the cloth surface and thus increasing the image density.

The heating temperature of the fabric is preferably 50°C to 250°C, and more preferably 80°C to 200°C. Within this range, at least partially, the moisture in the undercoat liquid can be removed from the fabric surface, and the amount of crosslinking agent (B) remaining on the fabric surface can be increased.
The heating time for the cloth should be set in conjunction with the heating temperature to achieve the above-mentioned effects. Specifically, the heating time for the cloth is preferably 10 seconds to 10 minutes, and more preferably 30 seconds to 3 minutes.

Heating methods include heating on a hot plate, heat pressing, atmospheric pressure steam, high-pressure steam, and thermofixing.
The time between applying the undercoat liquid to the fabric and heating the fabric is not particularly limited, but it is preferable to do so quickly, for example, within 60 seconds, within 30 seconds, or within 10 seconds. Depending on the manufacturing equipment, the time between applying the undercoat liquid to the fabric and heating the fabric may be 1 minute or more, 10 minutes or more, or 1 hour or more.

In the second step, water-based ink can be applied to the fabric to which the undercoat liquid was applied in the first step using an inkjet recording method. The water-based ink may contain urethane resin (A), pigment, and water, and may not contain a crosslinking agent; details are as described above. If drying or heating is performed after the application of the undercoat liquid, the water-based ink will be applied to the dried or heated fabric.
The inkjet recording method is not particularly limited; a serial inkjet recording device or a line-head inkjet recording device may be used. Line-head inkjet recording devices are capable of high-speed printing and are suitable for mass production of printed materials.
The inkjet method is not particularly limited and may be any method such as a piezo method, electrostatic method, or thermal method. It is preferable to eject ink droplets from the inkjet head based on a digital signal and print an image by adhering the ejected ink droplets to the fabric.

The amount of water-based ink applied to the fabric may be 1 to 50 g/ ^m² , 5 to 30 g/ ^m² , or 10 to 20 g/ ^m² . This range is within which an ink image can be formed with appropriate density and reproducibility. Furthermore, this range varies depending on the content ratio of urethane resin (A) contained in the water-based ink, but it is within the range within which an appropriate amount of urethane resin (A) contained in the water-based ink can be applied to the fabric.
When water-based ink is applied to the fabric, the amount of urethane resin (A) applied to the fabric may be 0.1 to 10 g/ ^m² , 0.5 to 5 g/ ^m² , or 1 to 3 g/ ^m² in terms of resin content.

In the third step, the cloth to which the water-based ink has been applied can be heated.
In the third step, heating the fabric promotes the formation of a urethane resin (A) coating on the fabric surface. Furthermore, the crosslinking reaction between the crosslinking agent (B) and the urethane resin (A) on the fabric surface is promoted. By promoting the crosslinking reaction, a reinforced urethane resin (A) coating with a crosslinked structure is formed on the fabric surface, further increasing its durability. In particular, the crosslinking agent (B) acts between the urethane resin (A) coating and the fabric, improving adhesion and further improving durability.

The heating temperature of the fabric may be such that the urethane resin (A) contained in the water-based ink can be softened, and preferably such that the urethane resin (A) can form a coating film on the fabric surface. Furthermore, the heating temperature of the fabric may be such that the coating film of urethane resin (A) and the crosslinking agent (B) can react on the fabric surface. Specifically, the heating temperature of the fabric is preferably 50°C to 250°C, and more preferably 80°C to 200°C.
The heating time for the cloth should be set in conjunction with the heating temperature to achieve the above-mentioned effects. Specifically, the heating time for the cloth is preferably 10 seconds to 10 minutes, and more preferably 30 seconds to 3 minutes.

The above-described method can be used as the heating method.
The time between applying the water-based ink to the fabric and heating the fabric is not particularly limited, but it is preferable to do so quickly, for example, within 60 seconds, within 30 seconds, or within 10 seconds. Depending on the manufacturing equipment, the time between applying the water-based ink to the fabric and heating the fabric may be 1 minute or more, 10 minutes or more, or 1 hour or more.

The base material for the printed material is preferably fabric. Examples of fabrics include woven fabrics, knitted fabrics, and nonwoven fabrics. The fibers constituting the fabric include, for example, inorganic fibers such as metal fibers, glass fibers, rock fibers, and mineral fiber; regenerated fibers such as cellulose-based and protein-based fibers; semi-synthetic fibers such as cellulose-based fibers; synthetic fibers such as polyamide, polyester, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polyvinyl alcohol, polyurethane, polyethylene, polypropylene, polystyrene, and polyfluoroethylene; and natural fibers such as cotton, linen, silk, and wool. At least one of these various fibers is selected.

The present invention will be described in detail below with reference to examples. The present invention is not limited to the following examples.

The formulations for the undercoat liquid and ink are shown in Tables 1 and 2, respectively. In the tables and the following explanation, the undercoat liquid or undercoat may be abbreviated as "UC," and unless otherwise specified, "%" represents "mass%." In each table, the pigment dispersion, resin emulsion, and water-soluble crosslinking agent are shown as the total amount including each active ingredient and medium.
"Ink mixing"
The raw materials were mixed according to the proportions shown in Table 1, and the mixture was filtered through a membrane filter with a pore size of 0.8 μm to obtain ink.
"Undercoat liquid preparation"
The raw materials were mixed according to the proportions shown in Table 2, and the mixture was filtered through a membrane filter with a pore size of 0.8 μm to obtain the undercoat liquid.

"Manufacturing of printed materials"
An undercoat liquid was applied to the base fabric, the resulting printed material was heated, and an aqueous ink was applied over the areas where the undercoat liquid had been applied. The resulting printed material was then heated to obtain a printed product. The combinations of ink and undercoat liquid, the amounts applied, and the heating conditions are shown in Tables 3 and 4.
I cut 100% cotton fabric to 52mm x 297mm.
An undercoat liquid was filled into a Mastermind inkjet printer "MMP813BT-C" (product name), and a solid image was printed using the amount of undercoat liquid applied as shown in the table.
In the table, examples where heating after undercoating is indicated as "Yes" involve applying the undercoat liquid to the fabric and then heating it at 150°C for 60 seconds using a Hotronix Fusion heat press.
A mastermind inkjet printer, model "MMP813BT-C" (product name), was filled with ink, and a solid image was printed by applying ink over an area treated with an undercoat liquid. The ink application amounts were as shown in the table.
After applying the ink, the material was heated at 150°C for 60 seconds using a Hotronix Fusion heat press.

The table shows the "Crosslinking Agent (B) / Urethane Resin (A) Application Ratio," which is the mass ratio of the amount of crosslinking agent (B) in the undercoat liquid to the amount of urethane resin (A) in the water-based ink. The amounts of urethane resin in the water-based ink and the water-soluble crosslinking agent in the undercoat liquid represent the application amounts (mass) per unit area of the region where the water-based ink and undercoat liquid are applied in layers.

The ingredients used are as follows:
Pigment dispersion "CAB-O-JET300" (product name): Carbon black self-dispersing pigment, pigment content 15% by mass, manufactured by Cabot Corporation.
Urethane resin emulsion "Superflex 740" (product name): Resin content 40% by mass, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
Urethane resin emulsion "Superflex 470" (product name): Resin content 38% by mass, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
Olefin resin emulsion "Arrowbase DC1010" (product name): Resin content 25% by mass, manufactured by Unitika Ltd.
Urethane resin emulsion "Takelac W6110" (product name): Resin content 32% by mass, manufactured by Mitsui Chemicals, Inc.
Surfactant "Orphine E1020" (product name): Acetylene glycol-based surfactant, 100% by mass of active ingredient, manufactured by Nisshin Chemical Industry Co., Ltd.

The water-soluble crosslinking agents "Carbodilite V-02" and "Carbodilite SV-02" are both trade names and are available from Nisshinbo Chemical Co., Ltd.
Surfactant "Sylface SAG014" (product name): Silicone-based surfactant, 100% by mass of active ingredient, manufactured by Nisshin Chemical Industry Co., Ltd.
Water-soluble solvents are available from companies such as Fujifilm Wako Pure Chemical Industries, Ltd. and Kanto Chemical Co., Ltd.

"Evaluation Method"
(Image quality of printed materials)
The OD value was measured in the image area of the printed surface of the textile using the "X-Rite eXact" spectrophotometer (product name) manufactured by Videojet X-Rite Corporation. The image quality was evaluated based on the measured OD values according to the following criteria.
A: 1.15 or higher.
B: 1.01 or higher and less than 1.15.
C: Less than 1.01.

(Friction fastness of printed materials (dry))
The fastness of the image area on the printed surface of the textile was evaluated in a dry state using the following procedure.
A JSPS testing machine RT-200 (Daiei Kagaku Seiki Seisakusho) was used for the colorfastness test. A white friction cloth was attached to the friction element of the testing machine, and the friction element was placed on the printed area without weight and rubbed back and forth 100 times. The friction cloth was 100% cotton Kanakin No. 3. Colorfastness was evaluated by assessing the staining (degree of coloring) of Kanakin No. 3 and the fading (degree of fading) of the printed material, using the following criteria on a grayscale.
A: Grade 4 or higher.
B: This is grade 3-4.
C: Grade 3 or lower.

(Friction fastness of printed materials (wet))
The fastness of the image area on the printed surface of the textile was evaluated in a wet state using the following procedure.
A JSPS testing machine RT-200 (Daiei Kagaku Seiki Seisakusho) was used for the colorfastness test. A friction cloth was attached to the friction element of the testing machine, and the friction element was placed on the printed area without any weight and rubbed back and forth 100 times. The friction cloth was 100% cotton Kanakin No. 3, moistened with an equal weight of deionized water. Colorfastness was evaluated by assessing staining of Kanakin No. 3 and fading of the printed material, using the following grayscale criteria.
A: It must be at least Level 3.
B: This is a 2nd-3rd grade level.
C: Grade 2 or lower.

(stability)
The ink's stability was evaluated by sealing the ink in a 500 mL glass container and leaving it at 70°C for one week. The viscosity change rate was measured before and after the period of storage, and the formation of foreign matter after storage was visually observed. The stability was evaluated according to the following criteria.
The ink viscosity was measured at 23°C using an Anton Paar Japan "Rheometer MCR302" (cone angle 1°, diameter 50 mm). The viscosity change rate was calculated using the following formula.
Viscosity change rate = [(Viscosity after standing × 100) / (Initial viscosity)] - 100 (%)
A: The viscosity change rate was between -10% and +10%, and no significant foreign matter formation was observed.
C: The viscosity change rate was less than -10% or greater than +10%, or significant foreign matter formation was observed.

As shown in the table, the ink stability was good for each example's combination of ink and undercoat liquid, application amount, and heating conditions, resulting in good print quality and friction fastness. The small viscosity change rate after standing and the absence of foreign matter observed after standing suggest that the inks in each example have excellent ejection performance.

Comparative Example 1 was an example where no undercoat liquid was applied before printing, and sufficient color fastness could not be obtained. Comparative Example 2 was an example using ink 1 containing resin and a crosslinking agent, resulting in reduced ink stability and the inability to obtain a printed material.

Claims (3)

The first step involves applying an undercoat liquid to a cloth using an inkjet recording method, which contains a crosslinking agent (B) and water, but does not contain a binder resin or a resin that reacts with the crosslinking agent.
The method includes a second step of applying an aqueous ink containing a urethane resin (A), a pigment, and water, but without a crosslinking agent, to the cloth using an inkjet recording method, and a third step of heating the cloth to which the aqueous ink has been applied.
A method for manufacturing a printed material that satisfies the following formula 1.
0.1 ≤ Amount of crosslinking agent (B) contained in the undercoat liquid / Amount of urethane resin (A) contained in the aqueous ink ≤ 5.0 (1)
In Equation 1, the amount of urethane resin (A) and the amount of crosslinking agent (B) applied represent the mass per unit area of the region where the aqueous ink and undercoat liquid are applied in layers. The method for producing a printed textile according to claim 1, wherein the crosslinking agent (B) is a water-soluble crosslinking agent. The method for producing a printed material according to claim 1 or 2, wherein the crosslinking agent (B) is a compound having a carbodiimide group.