Aqueous maintenance liquid, ink set, maintenance method for liquid applying device, inkjet recording method, and inkjet recording device

Abstract

To provide aqueous maintenance liquid which easily recovers discharge failures of a liquid applying device for discharging aqueous ink capable of recording an image having good scratch resistance, and has good member liquid-contact property to the liquid applying device.SOLUTION: An aqueous maintenance liquid is used in a liquid applying device for discharging aqueous ink containing a coloring material and resin particles. The resin particles contain at least one selected from the group consisting of acrylic resin particles, styrenic resin particles, urethane-based resin particles, and polyester-based resin particles. A contact part with the aqueous ink in the liquid applying device contains an epoxy resin composition obtained by polymerizing an epoxy resin, and a curing agent reactive with the epoxy resin. The aqueous maintenance liquid contains a water-soluble compound represented by the following general formula (1). Formula (1): R1-X-R2. In the general formula (1), X represents a sulfonyl group or a sulfoxide group, and R1 and R2 are connected with each other and do not form a ring, and each independently represent an alkyl group which may be substituted with a hydroxyl group.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an aqueous maintenance liquid, an ink set, a maintenance method for a liquid application device, an inkjet recording method, and an inkjet recording device. [Background technology]

[0002] In recent years, inkjet recording apparatuses have been increasingly used in the fields of commercial printing and industrial printing. In these printing fields, the performance of recorded matter is required to be higher in abrasion resistance than in the so-called home printing field.

[0003] In order to record images with good abrasion resistance, there is a method of using an ink containing resin particles. When resin particles are added to the ink, the solid content increases accordingly. Therefore, when the inkjet recording device is not used for a long period of time, or when the liquid application device is not properly capped due to a power outage during operation, the liquid components such as water in the ink evaporate, and solidified matter is likely to occur in the ink flow path such as the nozzle of the liquid application device. As a result, ink ejection failure may occur, and recording failure may occur.

[0004] In addition to adjusting the composition of the ink itself to prevent ink flow path sticking, one possible method is to use a maintenance liquid (also called a recovery liquid or cleaning liquid) to prevent or resolve sticking of the ink flow path.

[0005] On the other hand, inks and maintenance liquids that can solve the problem of ink flow path adhesion come into contact with components in a liquid application device of an inkjet recording device during use, and therefore are required to be suitable for the components in the liquid application device (hereinafter also referred to as liquid contact properties). In particular, liquid contact properties with adhesives used in the liquid application device are considered to be important. Regarding the compatibility of the ink flow path adhesion recovery properties of the liquid application device and liquid contact properties with the liquid application device, for example, Patent Document 1 proposes a maintenance liquid that contains at least one amide-based solvent or lactone-based solvent. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2022-159238 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present inventors have studied a maintenance liquid that can achieve both adhesion recovery properties of the ink flow path of the liquid deposition device and liquid contact properties with the liquid deposition device, with reference to the technology disclosed in Patent Document 1. As a result, they have found that there is room for improvement in order to achieve higher levels of adhesion recovery properties and liquid contact properties.

[0008] Therefore, an object of the present invention is to provide an aqueous maintenance liquid that is easy to recover from adhesion in the ink flow paths of a liquid-applying device that ejects aqueous ink capable of recording images with good abrasion resistance, and that has good liquid contact with the liquid-applying device. Another object of the present invention is to provide an ink set, a maintenance method for the liquid-applying device, an inkjet recording method, and an inkjet recording device that use this aqueous maintenance liquid. [Means for solving the problem]

[0009] That is, according to the present invention, there is provided an aqueous maintenance liquid for use in a liquid-applying device that ejects an aqueous ink containing a colorant and resin particles, the resin particles containing at least one type selected from the group consisting of acrylic resin particles, styrene-based resin particles, urethane-based resin particles, and polyester-based resin particles, a contact portion of the liquid-applying device that comes into contact with the aqueous ink contains an epoxy resin composition in which an epoxy resin and a curing agent that reacts with the epoxy resin are polymerized, and the aqueous maintenance liquid contains a water-soluble compound represented by the following general formula (1): R 1 -XR 2 (1) In the general formula (1), X represents a sulfonyl group or a sulfoxide group, and R 1 and R 2 do not combine with each other to form a ring, and each independently represent an alkyl group which may be substituted with a hydroxyl group. Effect of the Invention

[0010] According to the present invention, it is possible to provide an aqueous maintenance liquid that is easy to recover from adhesion in an ink flow path of a liquid-applying device that ejects an aqueous ink capable of recording an image with good abrasion resistance, and that has good liquid contact with the liquid-applying device. Furthermore, according to the present invention, it is possible to provide an ink set, a maintenance method for the liquid-applying device, an inkjet recording method, and an inkjet recording device that use this aqueous maintenance liquid. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram illustrating an embodiment of an inkjet recording apparatus of the present invention. [Diagram 2] FIG. 2 is a perspective view showing an example of a liquid application device. [Diagram 3] FIG. 2 is a schematic cross-sectional view of a liquid application device. [Figure 4] FIG. 2 is a cross-sectional perspective view showing an example of a discharge element substrate. [Diagram 5] FIG. 2 is a schematic diagram showing an example of a liquid supply system. [Figure 6] FIG. 2 is a perspective view showing an example of a capping tray. [Figure 7] FIG. 2 is a perspective view illustrating an example of a cleaning tray. [Figure 8] FIG. 4 is a schematic diagram showing an example of a supply system of the maintenance device. [Figure 9] FIG. 2 is a perspective view illustrating an example of a cleaning unit. [Figure 10A] FIG. 2 is a perspective view illustrating an example of a maintenance liquid deposition device. [Figure 10B] 10B is a cross-sectional view taken along line AA in FIG. 10A, illustrating an example of a maintenance liquid deposition device. [Figure 10C]10B is a cross-sectional view taken along line BB in FIG. 10A, illustrating an example of a maintenance liquid deposition device. [Figure 11] FIG. 4 is a schematic diagram showing an example of the positional relationship between a liquid application device and a cleaning unit. [Figure 12] FIG. 11 is a schematic diagram showing an example of a cleaning operation. [Figure 13] FIG. 13 is a schematic diagram showing another example of the heating unit. [Figure 14] FIG. 11 is a schematic diagram showing another example of the fixing unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will be described in more detail below with reference to preferred embodiments. In the present invention, when the compound is a salt, the salt is present in the ink in the form of dissociation into ions, but for convenience, it is expressed as "containing a salt." In addition, the aqueous ink and reaction liquid for inkjet printing may be simply referred to as "ink" and "reaction liquid." Physical property values ​​are values ​​at room temperature (25°C) unless otherwise specified. When "(meth)acrylic acid" and "(meth)acrylate" are written, they mean "acrylic acid, methacrylic acid" and "acrylate, methacrylate," respectively.

[0013] In order to make it possible to record an image with good abrasion resistance, an ink containing resin particles and coloring material is used, and the ink is discharged from a liquid application device of an inkjet recording device to record an image on a recording medium. Ink containing resin particles has an increased solid content due to the inclusion of resin particles, and therefore, when liquid components such as water in the ink evaporate, the coloring material and resin particles aggregate, and adhesion that blocks the ink flow path such as the nozzle of the liquid application device is likely to occur. This phenomenon of adhesion of the ink flow path is particularly likely to occur when the inkjet recording device is not used for a long period of time, or when the liquid application device is not properly capped due to a power outage during operation. The present inventors have studied ways to improve the adhesion of the ink flow path by changing the composition of the ink, but have not been able to find a fundamental solution due to the balance with other performance required of the ink.

[0014] The inventors therefore came up with the concept of a maintenance liquid that dissolves the resin particles in the solidified matter in the ink flow path, creating gaps in the solidified matter and allowing the liquid to permeate the entire flow path, thereby recovering from the solidified state. They then conducted a detailed study on the relationship between the molecular structures of the resin particles contained in the ink and the water-soluble compound contained in the maintenance liquid.

[0015] Resins forming resin particles used to impart high abrasion resistance to a recorded image generally include acrylic resins, styrene resins, urethane resins, and polyester resins. As a result of the inventors' investigations, a previously undiscovered finding was revealed that a water-soluble compound having a sulfonyl group or a sulfoxide group and represented by the following general formula (1) is highly effective as a component of a maintenance liquid for dissolving these resins. R 1 -XR 2 (1) In the general formula (1), X represents a sulfonyl group or a sulfoxide group, and R 1 and R 2 do not combine with each other to form a ring, and each independently represent an alkyl group which may be substituted with a hydroxyl group.

[0016] The water-soluble compound represented by the general formula (1) has the following characteristics (a) to (c): (a) the sulfonyl group and sulfoxide group are highly polar due to the difference in electronegativity between the sulfur atom and the oxygen atom, with the sulfur atom having a positive charge and the oxygen atom having a negative charge; (b) the sulfur atom is shielded by other atoms, so the positive charge is not visible on the surface, and the negative charge of the oxygen atom is visible on the surface, so it is likely to interact with the positive charge of other molecules; (c) the sulfur atom is in a three-dimensional arrangement with adjacent atoms (oxygen atoms, carbon atoms of alkyl groups, etc.).

[0017] Therefore, the present inventors have clarified that the mechanism of the fixation recovery of the water-soluble compound represented by the general formula (1) is the following (d) to (f). That is, (d) the hydrophobic group of the water-soluble compound represented by the general formula (1) interacts with the resin particles, and the oxygen atom of the water-soluble compound and the hydrogen atom of water form a hydrogen bond, so that the resin particles that have interacted with the water-soluble compound are solubilized and dispersed in water. In addition, since the hydrophobic group and the oxygen atom of the water-soluble compound are present in a three-dimensional position, the interaction between the resin particles and water is further promoted. (e) The water-soluble compound represented by the general formula (1) interacts with the resin particles, and the fixed resin particles are removed, so that the colorant is exposed on the surface of the fixed matter. (f) Since the positive charge of the sulfur atom of the water-soluble compound represented by the general formula (1) is not exposed on the surface, it does not interact with the anion component of the colorant, suppressing the so-called action as a salt, and improving redispersion in water.

[0018] On the other hand, as mentioned above, the components of the maintenance liquid that dissolve the resin particles have poor wettability with the adhesive that bonds the components (parts) in the ink flow path of the liquid application device, and there is a concern that this could significantly degrade the functionality of the liquid application device.

[0019] The present inventors have found that the liquid-applying device using an epoxy resin composition obtained by polymerizing an epoxy resin and a curing agent that reacts with the epoxy resin as an adhesive used in a portion that comes into contact with the ink has good liquid contact with the maintenance liquid containing the water-soluble compound. The present inventors have also clarified that the liquid contact with the liquid-applying device is good due to the following mechanisms (g) and (h). That is, (g) the water-soluble compound represented by general formula (1) is highly polar, and therefore does not easily interact with the epoxy resin composition, which has a relatively low polarity. (h) The sulfur atom of the water-soluble compound represented by general formula (1) is three-dimensionally arranged with adjacent atoms, and therefore does not easily penetrate into the molecular structure of the epoxy resin composition.

[0020] For the above reasons, an aqueous maintenance liquid containing a water-soluble compound represented by general formula (1) is used in a liquid application device that contains an epoxy resin composition in which an epoxy resin and a curing agent that reacts with the epoxy resin are polymerized at the portion that contacts the ink. This makes it possible to provide an aqueous maintenance liquid that has good liquid contact with the liquid application device. Furthermore, even if an aqueous ink containing resin particles is used as the ink to be ejected from the liquid application device in order to record an image with good abrasion resistance, it is possible to provide an aqueous maintenance liquid that has excellent adhesion recovery properties in ink flow paths such as the nozzles of the liquid application device.

[0021] <Maintenance liquid, ink set, maintenance method for liquid application device, inkjet recording method, inkjet recording device> The aqueous maintenance liquid of the present invention (also referred to simply as "maintenance liquid" in this specification) is an aqueous maintenance liquid used in a liquid application device that ejects aqueous ink containing a coloring material and resin particles.

[0022] The ink set of the present invention is an ink set including an aqueous ink containing a coloring material and resin particles, and an aqueous maintenance liquid used in a liquid application device that ejects the aqueous ink.

[0023] The maintenance method for a liquid application device of the present invention (hereinafter also simply referred to as the "maintenance method") includes a step of applying an aqueous maintenance liquid to a liquid application device that ejects an aqueous ink containing a colorant and resin particles to record an image on a recording medium.

[0024] The inkjet recording method of the present invention (hereinafter also simply referred to as the "recording method") includes the steps of: ejecting an aqueous ink containing a colorant and resin particles from a liquid application device to record an image on a recording medium; and applying an aqueous maintenance liquid to the liquid application device.

[0025] The inkjet recording apparatus (hereinafter also simply referred to as the "recording apparatus") of the present invention comprises an aqueous ink containing a colorant and resin particles, a liquid application device that ejects the aqueous ink to record an image on a recording medium, and an aqueous maintenance liquid that is applied to the liquid application device.

[0026] The resin particles include at least one selected from the group consisting of acrylic resin particles, styrene resin particles, urethane resin particles, and polyester resin particles. The portion of the liquid application device that comes into contact with the water-based ink includes an epoxy resin composition formed by polymerizing an epoxy resin and a curing agent that reacts with the epoxy resin. The water-based maintenance liquid is characterized by containing a water-soluble compound represented by the following general formula (1): R 1 -XR 2 (1) In the general formula (1), X represents a sulfonyl group or a sulfoxide group, and R 1 and R 2 do not combine with each other to form a ring, and each independently represent an alkyl group which may be substituted with a hydroxyl group.

[0027] (Inkjet recording device) The inkjet recording apparatus will be described in detail below with reference to the drawings. Fig. 1 is a schematic diagram showing one embodiment of the inkjet recording apparatus of the present invention. The inkjet recording apparatus of this embodiment is an inkjet recording apparatus that records an image on a recording medium using ink and a reaction liquid containing a reactant that reacts with the ink. The X direction, Y direction, and Z direction respectively indicate the width direction (total length direction), depth direction, and height direction of the inkjet recording apparatus. The recording medium is transported in the X direction.

[0028] The inkjet recording apparatus 100 of the embodiment shown in FIG. 1 is configured to include a recording unit 1000, a heating unit 2000, a fixing unit 3000, a cooling unit 4000, an inverting unit 5000, and a paper discharge unit 6000. In the recording unit 1000, various liquids are applied by a liquid application unit 1200 to a recording medium 1100 conveyed from a paper feeder 1400 by a conveying member 1300. In the heating unit 2000, the liquid applied to the recording medium 1100 is heated by a heating unit 2100, and volatile components such as water in the liquid are evaporated and dried. In the fixing unit 3000, a fixing member 3100 is brought into contact with the area of ​​the recording medium 1100 to which the liquid has been applied, and heated to promote fixing of the image to the recording medium 1100. The recording medium 1100 is then cooled by a cooling member 4100 of the cooling unit 4000. When an image is to be recorded on the back side following the front side (recording surface), the recording medium 1100 is first inverted by an inversion device 5100 of the inversion section 5000. Next, an image is recorded on the back side in the same manner as for the front side, and then the recording medium is transported by a transport member 6100 of the paper discharge section 6000 and stacked and stored in the recording medium storage section 6200. In addition, the liquid deposition performance of the liquid deposition device 1200 is restored by a maintenance device 1600. Here, a configuration having a heating section 2000 and a fixing section 3000 will be described as an example, but the heating section and the fixing section may be omitted depending on the recording conditions (type of ink or recording medium, recording speed, etc.).

[0029] Any recording medium may be used as the recording medium 1100. For example, recording media having ink absorbency (permeability) such as recording media without a coating layer, such as plain paper, uncoated paper, and synthetic paper, and recording media with a coating layer, such as printing paper, glossy paper, and art paper, may be used. In addition, recording media having no permeability, such as films or sheets made of resin materials such as polyvinyl chloride (PVC) and polyethylene terephthalate (PET), may be used. The basis weight (g / m2) of the recording medium 1100 may be determined by the following formula: 2 ) is 30g / m 2 More than 500g / m 2 It is preferable that the thickness is less than 50 g / m 2 More than 450g / m 2 It is even more preferable that:

[0030] [Recording Section] The recording unit 1000 includes a liquid applying device 1200. The liquid applying device 1200 includes a reaction liquid applying device 1201 and an ink applying device 1202. The reaction liquid applying device 1201 shown in FIG. 1 is an example of a unit using an inkjet type ejection head. In addition, the reaction liquid applying device may be configured using a gravure coater, an offset coater, a die coater, a blade coater, or the like. The reaction liquid may be applied by the reaction liquid applying device 1201 either before or after the ink application as long as it can come into contact with the ink on the recording medium 1100. However, in order to record high-quality images on various recording media having different liquid absorption characteristics, it is preferable to apply the reaction liquid before the ink is applied. An inkjet type ejection head (recording head) is used as the ink applying device 1202. The ejection method of the ejection head as the liquid applying device 1200 can be exemplified by a method of ejecting liquid by generating film boiling in the liquid by an electrothermal converter to form bubbles, and a method of ejecting liquid by an electromechanical converter. In the recording method and recording apparatus of the present invention, for example, by using the above-mentioned liquid application apparatus 1200 (ink application apparatus 1202), it is possible to discharge ink from the discharge ports of the liquid application apparatus and record an image on a recording medium.

[0031] The liquid deposition device 1200 is a line head extending in the Y direction, and has ejection ports arranged in a range that covers an image recording area of ​​the widest usable recording medium. The ejection head has an ejection port surface 1207 (FIG. 4) on which ejection ports are formed on its lower side (the recording medium 1100 side), and the ejection port surface faces the recording medium 1100 at a very small distance of about a few millimeters.

[0032] A plurality of ink applicators 1202 may be provided to apply ink of each color to the recording medium 1100. For example, when recording images of each color using yellow ink, magenta ink, cyan ink, and black ink, four ink applicators 1202 for ejecting the above four types of ink are arranged side by side in the X direction. Hereinafter, the ink and the reaction liquid may be collectively referred to as "liquid".

[0033] FIG. 2 is a perspective view showing an example of a liquid applying device. The liquid applying device 1200 shown in FIG. 2 is a line head, and a plurality of ejection element substrates 1203, each having an ejection port array, are arranged in a straight line. A plurality of ejection port arrays are arranged on the ejection element substrate 1203. A protective member (hereinafter, also referred to as a "first protective member") 1224 for protecting the plurality of ejection element substrates 1203 is arranged on the outer periphery of the ejection element substrates 1203 arranged in a straight line. In addition, the liquid applying device 1200 has a first positioning portion 1225 used for positioning a capping unit described later on both ends. Specifically, a first contact portion 1225a, which is a recess having a cone-shaped inclined surface, is provided on the front side of the drawing in the longitudinal direction (Y direction) of the liquid applying device 1200. Further, a second contact portion 1225b which is a groove portion having two V-shaped flat surfaces, and a third contact portion 1225c which is a flat surface are provided on the rear side of the liquid application device 1200 in the longitudinal direction (Y direction) in the drawing.

[0034] 3 is a schematic cross-sectional view of a liquid applying device. The liquid applying device 1200 includes an ejection element substrate 1203 that ejects liquid, a support member 1232 that supports the ejection element substrate 1203 and has a supply flow path 1231 that supplies liquid to the ejection element substrate 1203, and a flow path member 1233 that supplies liquid to the supply flow path 1231. The flow path member 1233 may be composed of a plurality of members. For example, the flow path member 1233 may be composed of a first flow path member 1234, a second flow path member 1235, and a third flow path member 1236 as shown in FIG. 3. In addition, as described above, a protection member 1224 for protecting the ejection element substrate 1203 can be provided on the outer periphery of the ejection element substrate 1203.

[0035] When manufacturing the liquid applying device 1200, it is necessary to bond the above-mentioned multiple flow path members 1233, the support member 1232, the ejection element substrate 1203, the protective member 1224, and the like with high accuracy. Therefore, the liquid applying device 1200 is assembled, for example, in the following procedure. An adhesive is applied to the support member 1232, the ejection element substrate 1203 is bonded, and the adhesive is fully cured. The third flow path member 1236 and the second flow path member 1235 are bonded together with an adhesive, and the first flow path member 1234 is further bonded to the second flow path member 1235 with an adhesive to manufacture the flow path member 1233. Next, the support member 1232, the first flow path member 1234 of the flow path member 1233, and the protective member 1224 are temporarily fixed together with an adhesive. Finally, the adhesive is fully cured. In other words, the liquid dispensing device 1200 can be manufactured by applying adhesive to at least one bonding surface between any two of the ejection element substrate 1203, the support member 1232, the flow path member 1233, and the protective member 1224, and then hardening the adhesive.

[0036] [Epoxy resin composition] An adhesive containing an epoxy resin and a curing agent that reacts with the epoxy resin is used as an adhesive that can be used in manufacturing the liquid application device 1200. As a result, an epoxy resin composition is formed by polymerization of the epoxy resin and the curing agent that reacts with the epoxy resin in the portion to which the adhesive is applied. The above two members are bonded via this epoxy resin composition (a cured epoxy resin product formed by polymerization of the above epoxy resin and the curing agent).

[0037] Therefore, in the liquid applying device 1200, the portion that comes into contact with the aqueous ink (contact portion with the aqueous ink) contains an epoxy resin composition obtained by polymerizing an epoxy resin and a curing agent that reacts with the epoxy resin. The epoxy resin and the curing agent are polymerized to form an adhesive for the liquid applying device that has high wettability with ink and maintenance liquid. The polymerization conditions can be adjusted arbitrarily depending on the type of epoxy resin and curing agent used. Examples of the polymerization conditions include a temperature of 10° C. or higher and 250° C. or lower, and a time of 1 minute or higher and 168 hours or lower. The polymerization can be confirmed by any method. Examples of the polymerization confirmation include measurement of molecular weight distribution and average molecular weight by gel permeation chromatography (GPC), and measurement of the degree of polymerization from the peak ratio of a specific site in the epoxy resin composition by nuclear magnetic resonance (NMR).

[0038] (Epoxy resin) Any conventionally known epoxy resin suitable for adhesive applications can be used without limitation as the epoxy resin used as a component of the epoxy resin composition used in the contact portion with the aqueous ink in the liquid application device 1200. Not only liquid epoxy resins, but also those that are solid by themselves at room temperature and that become liquid when heated or become liquid as an epoxy resin component in the adhesive composition can be used.

[0039] Examples of epoxy resins that are liquid at room temperature include alicyclic epoxy resins, aromatic epoxy resins, aliphatic epoxy resins, etc. One or more of these can be used.

[0040] Examples of alicyclic epoxy resins include polyglycidyl ethers of polyhydric alcohols having at least one alicyclic ring.Other examples include compounds containing cyclohexene oxide structures and compounds containing cyclopentene oxide structures obtained by epoxidizing compounds containing cyclohexene rings and compounds containing cyclopentene rings with an oxidizing agent.Other examples include compounds containing vinylcyclohexane oxide structures obtained by epoxidizing compounds containing vinylcyclohexane structures with an oxidizing agent. Specifically, for example, hydrogenated bisphenol A diglycidyl ether, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexyl carboxylate, 3,4-epoxy-1-methylcyclohexyl-3,4-epoxy-1-methylcyclohexane carboxylate, 6-methyl-3,4-epoxycyclohexylmethyl-6-methyl-3,4-epoxycyclohexane carboxylate, 3,4-epoxy-3-methylcyclohexylmethyl-3,4-epoxy-3-methylcyclohexane carboxylate, 3,4-epoxy-5-methylcyclohexylmethyl-3,4-epoxy-5-methylcyclohexane carboxylate, 2-(3,4-epoxycyclohexyl-5,5-sulfonyl)-2,2-dimethylphenyl ether ... pyro-3,4-epoxy)cyclohexane-metadioxane, bis(3,4-epoxycyclohexylmethyl)adipate, vinylcyclohexene dioxide, 4-vinylepoxycyclohexane, bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, 3,4-epoxy-6-methylcyclohexylcarboxylate, methylene bis(3,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylene glycol di(3,4-epoxycyclohexylmethyl)ether, ethylene bis(3,4-epoxycyclohexanecarboxylate), dioctyl epoxyhexahydrophthalate, di-2-ethylhexyl epoxyhexahydrophthalate, and the like.

[0041] Examples of aromatic epoxy resins include polyglycidyl ethers of polyhydric phenols having at least one aromatic ring or their alkylene oxide adducts, or those containing a naphthalene ring, such as glycidyl ethers of bisphenol A, bisphenol F, and compounds obtained by further adding alkylene oxide to these, epoxy novolac resins, bisphenol A novolac diglycidyl ether, and bisphenol F novolac diglycidyl ether.

[0042] Examples of aliphatic epoxy resins include polyglycidyl ethers of aliphatic polyhydric alcohols or their alkylene oxide adducts, polyglycidyl esters of aliphatic long-chain polybasic acids, epoxy-containing compounds obtained by oxidizing aliphatic long-chain unsaturated hydrocarbons with an oxidizing agent, homopolymers of glycidyl acrylate or glycidyl methacrylate, and copolymers of glycidyl acrylate or glycidyl methacrylate. Specific examples include glycidyl ethers of polyhydric alcohols such as 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, triglycidyl ether of glycerin, triglycidyl ether of trimethylolpropane, tetraglycidyl ether of sorbitol, hexaglycidyl ether of dipentaerythritol, diglycidyl ether of polyethylene glycol, and diglycidyl ether of polypropylene glycol; polyglycidyl ethers of polyether polyols obtained by adding one or more alkylene oxides to an aliphatic polyhydric alcohol such as propylene glycol or glycerin; and diglycidyl esters of aliphatic long-chain dibasic acids.

[0043] Further examples include monoglycidyl ethers of aliphatic higher alcohols, phenol, cresol, butylphenol, and monoglycidyl ethers of polyether alcohols obtained by adding alkylene oxides to these, glycidyl esters of higher fatty acids, epoxidized soybean oil, epoxy octyl stearate, epoxy butyl stearate, and epoxidized linseed oil.

[0044] Examples of epoxy resins that are solid at room temperature include epoxy resins having a biphenyl skeleton, a naphthalene skeleton, a cresol novolac skeleton, a trisphenolmethane skeleton, a dicyclopentadiene skeleton, or a phenolbiphenylene skeleton.

[0045] From the viewpoint of liquid contact properties, the epoxy resin preferably contains a bisphenol A type epoxy resin.

[0046] (hardening agent) As the curing agent that reacts with the epoxy resin used as a component of the epoxy resin composition used in the contact portion with the aqueous ink in the liquid application device, any known curing agent can be used without limitation. As the curing agent, for example, an amine-based curing agent, an acid anhydride-based curing agent, an acid-based curing agent, and a phenol-based curing agent can be used. One or more of these can be used. The curing agent preferably includes at least one selected from the group consisting of an amine-based curing agent and an acid anhydride-based curing agent.

[0047] Examples of the amine curing agent include primary amines, secondary amines, and tertiary amines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenediamine, diethylaminopropylamine, N-aminoethylpiperazine, Larmine C-260 (BASF product name), menthenediamine, isophoronediamine, metaxylylenediamine, metaxylylenediamine, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, diaminodiethyltoluene, 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, epoxy-imidazole adduct, dicyandiamide, and modified amines such as amine adducts in which an epoxy resin is partially added to a polyamine.

[0048] Examples of the acid anhydride curing agent include aliphatic acid anhydrides such as dodecenyl succinic anhydride, alicyclic acid anhydrides such as methyltetrahydrophthalic anhydride, aromatic acid anhydrides such as phthalic anhydride and trimellitic anhydride, and halogen-based acid anhydrides such as HET anhydride.

[0049] The amount of the curing agent used is not particularly limited, but in order to better exhibit the properties of the resin component such as low-temperature curing property, ink resistance, and adhesion, it is preferable that the amount of the curing agent used be within the range of 1 part by mass or more and 50 parts by mass or less, based on 100 parts by mass of all the resin components constituting the epoxy resin composition.

[0050] (Other Ingredients) In addition to the above components, the epoxy resin composition may contain various additives such as a filler and a silane coupling agent, if necessary.

[0051] FIG. 4 is a cross-sectional perspective view showing an example of a discharge element substrate. The discharge element substrate 1203 shown in FIG. 4 includes a discharge port forming member 1206 having a discharge port 1204 opened therein, and a substrate 1205 having discharge elements (not shown) disposed thereon. The discharge port forming member 1206 and the substrate 1205 are laminated to form a first flow path 1208 and a second flow path 1209 through which liquid flows. The first flow path 1208 is a region from an inlet 1212 through which liquid flows in from an inflow path 1210 to a portion between the discharge port 1204 and the discharge element (FIG. 5, liquid chamber 1508). The second flow path 1209 is a region from a portion between the discharge port 1204 and the discharge element (FIG. 5, liquid chamber 1508) to an outlet 1213 through which liquid flows out to an outlet path 1211. For example, by creating a pressure difference between the inlet 1212 and the outlet 1213, such as a high-pressure inlet 1212 and a low-pressure outlet 1213, liquid can be made to flow from the high-pressure side to the low-pressure side (in the direction of the arrow in FIG. 4). The liquid that has passed through the inlet 1210 and the inlet 1212 enters the first flow path 1208. Then, the liquid that has passed through the portion between the outlet 1204 and the ejection element (liquid chamber 1508 in FIG. 5) flows through the second flow path 1209 and the outlet 1213 to the outlet path 1211.

[0052] [Supply system] FIG. 5 is a schematic diagram showing an example of a supply system for liquid such as ink. The supply unit 1500 of the liquid deposition apparatus 1200 shown in FIG. 5 is configured to include a first circulation pump (high pressure side) 1501, a first circulation pump (low pressure side) 1502, a sub-tank 1503, and a second circulation pump 1505. The sub-tank 1503 connected to a main tank 1504, which is a liquid storage unit, has an air communication port (not shown) and can discharge air bubbles mixed in the liquid to the outside of the circulation system. The sub-tank 1503 is also connected to a refill pump 1506. The liquid is consumed in the liquid deposition apparatus 1200 by discharging (discharging) the liquid from the discharge port for image recording, suction recovery, etc. The refill pump 1506 transfers the liquid corresponding to the consumed amount from the main tank 1504 to the sub-tank 1503.

[0053] The first circulation pump (high pressure side) 1501 and the first circulation pump (low pressure side) 1502 cause the liquid in the liquid deposition device 1200, which is caused to flow out from a connection part (inlet part) 1507, to flow into a sub tank 1503. It is preferable to use a positive displacement pump having a quantitative liquid delivery capability as the first circulation pump (high pressure side) 1501, the first circulation pump (low pressure side) 1502, and the second circulation pump 1505. Examples of such a positive displacement pump include a tube pump, a gear pump, a diaphragm pump, and a syringe pump. When the ejection element substrate 1203 is driven, the first circulation pump (high pressure side) 1501 and the first circulation pump (low pressure side) 1502 can cause the liquid to flow from a common inlet channel 1514 toward a common outlet channel 1515.

[0054] The negative pressure control unit 1509 includes two pressure adjustment mechanisms with mutually different control pressures. The pressure adjustment mechanism (high pressure side) 1510 and the pressure adjustment mechanism (low pressure side) 1511 are connected to a common inflow channel 1514 and a common outflow channel 1515 in the ejection element substrate 1203 via a supply unit 1513 provided with a filter 1512 for removing foreign matter from the liquid. The ejection element substrate 1203 is provided with the common inflow channel 1514, the common outflow channel 1515, and the inflow channel 1210 and the outflow channel 1211 that communicate with the liquid chamber 1508, which is a portion between the ejection port 1204 and the ejection element (not shown). Since the inflow channel 1210 and the outflow channel 1211 communicate with the common inflow channel 1514 and the common outflow channel 1515, respectively, a flow (arrow in FIG. 5) is generated in which part of the liquid flows from the common inflow channel 1514 through the inside of the liquid chamber 1508 to the common outflow channel 1515. The arrows in Fig. 4 indicate the flow of liquid inside the liquid chamber 1508. That is, as shown in Fig. 4, the liquid in the first flow path 1208 flows to the second flow path 1209 via the gap between the ejection port 1204 and the ejection element.

[0055] 5, a pressure adjustment mechanism (high pressure side) 1510 is connected to the common inflow channel 1514, and a pressure adjustment mechanism (low pressure side) 1511 is connected to the common outflow channel 1515, so that a pressure difference occurs between the inflow channel 1210 and the outflow channel 1211. As a result, a pressure difference also occurs between an inlet 1212 (FIG. 4) communicating with the inflow channel 1210, and an outlet 1213 (FIG. 4) communicating with the outflow channel 1211. When liquid is caused to flow by the pressure difference between the inlet 1212 and the outlet 1213, it is preferable to control the flow velocity (mm / s) of the liquid to be 0.1 mm / s or more and 10.0 mm / s or less.

[0056] [Transport system] As shown in FIG. 1, the recording unit 1000 is configured to include a liquid applying device 1200 and a conveying member 1300 that conveys the recording medium 1100. The liquid applying device 1200 applies a reaction liquid and ink to a desired position of the recording medium 1100 conveyed by the conveying member 1300. Each liquid applying device 1200 receives an image signal of recording data and applies the necessary reaction liquid and ink to each position. FIG. 1 shows the conveying member 1300 in the form of a conveying belt, but a spur, a conveying drum, or the like may be used as long as it has the function of conveying the recording medium 1100. In order to improve the conveying accuracy, a material that can fix the recording medium 1100 can be used as the conveying member 1300. Specifically, a method of providing a hole in the conveying member 1300 and fixing the recording medium 1100 by sucking from the back side, a method of forming the conveying member 1300 from an appropriate material and fixing the recording medium 1100 by electrostatic adsorption, etc. can be mentioned.

[0057] [Maintenance system] As shown in FIG. 1, the recording unit 1000 is configured to include a maintenance device 1600. The maintenance device 1600 performs maintenance to restore the liquid ejection performance of the liquid deposition device 1200. The maintenance device 1600 is configured to include, for example, a capping unit 1701 (see FIG. 6) that protects the ejection port surface 1207 (see FIG. 4) and a cleaning unit 1801 (see FIG. 7) that cleans the ejection port surface 1207 (see FIG. 4). The maintenance device 1600 further includes a drive device and a rail (not shown), and is configured to be movable in the X direction of FIG. 1 along the rail. When maintenance of the liquid deposition device 1200 is performed, the maintenance device moves directly below the liquid deposition device 1200, and when maintenance of the liquid deposition device 1200 is not performed, the maintenance device moves to a position retreated from directly below the liquid deposition device 1200.

[0058] Next, the configuration of the maintenance device 1600 will be described. The maintenance device 1600 shown in Fig. 1 is equipped with a capping tray 1700 having a capping unit 1701 (see Fig. 6) and a cleaning tray 1800 having a cleaning unit 1801 (see Fig. 7). The capping tray 1700 and the cleaning tray 1800 are configured to be movable in the longitudinal direction of the inkjet recording apparatus (X direction in Fig. 1) by a driving motor (not shown) and rails provided on the housing of the inkjet recording apparatus 100.

[0059] FIG. 6 is a perspective view showing an example of a capping tray 1700. The capping tray 1700 has a plurality of capping units 1701 for protecting the ejection port surfaces of the reaction liquid applying device 1201 and the ink applying device 1202, which are the liquid applying device 1200. The capping unit 1701 has a plurality of spherical second positioning portions 1702 used for positioning the capping unit 1701 with respect to the liquid applying device 1200. One second positioning portion 1702 is disposed at one end in the longitudinal direction of one capping unit 1701, and two second positioning portions 1702 are disposed at the other end. The positions of the liquid applying device 1200 and the capping unit 1701 are regulated by abutment between the first positioning portions 1225 (see FIG. 2) provided at both ends of the liquid applying device 1200 and the second positioning portions 1702 of the capping unit 1701. The capping unit 1701 covers the discharge port surface side of the liquid deposition apparatus 1200 when the liquid deposition apparatus 1200 is not in use, thereby protecting the discharge port surface 1207 (see FIG. 4) of the liquid deposition apparatus 1200 and enabling suction by a negative pressure deposition apparatus described later.

[0060] A capping liquid supply flow path 1703 shown in Fig. 6 is a flow path through which the maintenance liquid is supplied to the capping unit 1701. As shown in Fig. 6, the capping liquid supply flow path 1703 of the capping unit 1701 corresponding to each liquid deposition device 1200 includes a plurality of cap upstream three-way valves 1704, and has a three-way valve upstream flow path and a three-way valve downstream flow path. The upstream side (the maintenance liquid sub-tank 1603 (see Fig. 8) side) of each cap upstream three-way valve 1704 is the three-way valve upstream flow path, and the downstream side is the three-way valve downstream flow path. The plurality of cap upstream three-way valves 1704 are supported by a three-way valve support member 1705 by a fixing method not shown.

[0061] FIG. 7 is a perspective view showing an example of a cleaning tray 1800. The cleaning tray 1800 has a plurality of cleaning units 1801 for cleaning the ejection port surface 1207. The cleaning tray 1800 also has a plurality of spherical third positioning parts 1802 used for positioning the cleaning units 1801 with respect to the liquid deposition device 1200. The third positioning parts 1802 are arranged on beam members 1803a and 1803b arranged on both sides of the width direction (Y direction in FIG. 1) of the recording medium 1100 to be conveyed inside the cleaning tray 1800. Three third positioning parts 1802 are required to position one liquid deposition device 1200 with respect to the cleaning tray 1800. Specifically, one third positioning part 1802 is arranged on the beam member 1803a on the front side of the figure in the Y direction in FIG. 1 in the cleaning tray 1800, and two third positioning parts 1802 are arranged on the beam member 1803b on the back side of the figure. The positions of the liquid deposition apparatus 1200 and the cleaning tray 1800 are regulated by abutment between first positioning portions 1225 provided on both ends of the liquid deposition apparatus 1200 and third positioning portions 1802 of the cleaning tray 1800 .

[0062] The configuration for positioning the first positioning portion 1225 and the second positioning portion 1702 and / or the third positioning portion 1802 is not limited to a configuration using a spherical positioning portion. For example, a configuration in which a part of the liquid deposition device 1200 is abutted against the inside of the capping unit 1701 or the cleaning tray 1800 may be used. Also, for example, a configuration in which the liquid deposition device 1200 and a hole provided in the capping unit 1701 or the cleaning tray 1800 are positioned using a pin may be used.

[0063] The cleaning unit 1801 includes a maintenance liquid applying device 1850, a liquid removing device 1860, and a negative pressure applying device 1870. The maintenance liquid applying device 1850 applies the maintenance liquid to the ejection port surface 1207 of the liquid applying device 1200. The liquid removing device 1860 is a device for removing the maintenance liquid from the ejection port surface 1207 of the liquid applying device 1200, and is a device that can remove the liquid, paper powder, maintenance liquid, and the like that are attached to the liquid applying device 1200. The negative pressure applying device 1870 is a device for removing ink that has adhered to the ejection port and removing bubbles in the first flow path 1208 and the second flow path 1209 by applying a negative pressure to the ejection port surface 1207 of the liquid applying device 1200 and sucking the ink. As shown in FIG. 7, the cleaning unit 1801 is configured to be movable along a wiping direction (direction D in FIG. 7) that is perpendicular to the transport direction of the recording medium 1100. The cleaning unit 1801 removes the liquid, paper powder, maintenance liquid, and the like from the ejection port surface 1207 of the liquid deposition device 1200 by means of a maintenance liquid deposition device 1850 , a liquid removal device 1860 , and a negative pressure deposition device 1870 .

[0064] (Maintenance equipment supply system) 8, a supply system such as a maintenance liquid supply path, a suction flow path, and a waste liquid flow path of the maintenance device 1600 will be described. The maintenance liquid is sent from a maintenance liquid pack 1601 to a maintenance liquid sub-tank 1603 by a pump 1602. The maintenance liquid can be sent from the maintenance liquid sub-tank 1603 to the capping unit 1701, the maintenance liquid deposition device 1850, and the negative pressure application device 1870 by a maintenance liquid supply pump 1604. The maintenance liquid supply pump 1604 is provided in a maintenance liquid and negative pressure supply unit 1650 (Y: yellow, M: magenta, C: cyan, Bk: black, P: reaction liquid) corresponding to the liquid deposition device 1200. In addition, the timing of supplying the maintenance liquid to the capping unit 1701, the maintenance liquid deposition device 1850, and the negative pressure application device 1870 can be controlled by each of opening and closing valves 1605, 1606, and 1607.

[0065] Negative pressure is applied to the capping unit 1701 and the negative pressure applying device 1870 by a suction pump 1616 connected to a negative pressure tank 1615. Negative pressure can be applied to each of the capping units 1701 and each of the negative pressure applying devices 1870 through the opening and closing valves 1617, 1618, and 1619 via each negative pressure tank 1615. When liquid is sucked using the capping unit 1701 and the negative pressure applying device 1870, waste liquid sucked from the liquid applying device 1200 is stored in the drain sub-tank 1613 from the negative pressure tank 1615 by the pump 1614. Then, the waste liquid is stored in the waste liquid tank 1611 from the drain sub-tank 1613 by the pump 1612. In addition, a collection tray 1630 for collecting the maintenance liquid overflowing from the maintenance liquid applying device 1850 is provided in the supply system, and the excess maintenance liquid is sent to the drain sub-tank 1613 by the pump 1621. The capacity of the waste liquid tank 1611 is detected by a waste liquid tank detection sensor (not shown), and when the capacity approaches the upper limit, the user is prompted to replace the waste liquid tank 1611.

[0066] The waste liquid from the reaction liquid deposition device 1201 is accommodated in a drain sub-tank 1633 for the reaction liquid by a pump 1634, separately from the waste liquid flow path from the ink deposition device 1202, and is stored in a waste liquid tank 1631 for the reaction liquid by a pump 1632. This prevents the reaction liquid and the ink from mixing in the waste liquid flow path, making it possible to suppress clogging of the flow path due to ink solidifying in the flow path.

[0067] As in the supply system described above, the maintenance liquid and negative pressure supply unit 1650 corresponding to each liquid deposition device is provided with a maintenance liquid supply pump 1604 and on-off valves 1605, 1606, and 1607 for controlling the supply of maintenance liquid to each flow path. The maintenance liquid and negative pressure supply unit 1650 is also provided with a negative pressure tank 1615, a suction pump 1616 for suction, and on-off valves 1617, 1618, and 1619 for controlling the application of negative pressure to each part. The maintenance liquid and negative pressure supply unit 1650 may be provided with a filter 1622.

[0068] (Operation to prevent flow path sticking of maintenance device) An operation for suppressing the flow passage sticking of the maintenance device will be described with reference to FIG. 8. When liquid is sucked from the liquid application device 1200 using the capping unit 1701, the liquid is prevented from sticking in the capping unit 1701 and in the supply system leading to the waste liquid tanks 1611 and 1631, causing blockage of the flow passage. For this purpose, after sucking the liquid, the liquid application device 1200 is separated from the capping unit 1701 and then an empty suction operation is performed. As a result, the liquid inside the capping unit 1701 and in the flow passage is sent to the waste liquid tanks 1611 and 1631, and then the cap upstream three-way valve 1704 is opened and the maintenance liquid is filled in the capping unit 1701 through the valve. Next, the empty suction operation is performed in the same manner to send the maintenance liquid to the waste liquid tanks 1611 and 1631, thereby cleaning the inside of the capping unit 1701 and in the flow passage, and thus preventing sticking in the supply system. In order to suppress sticking at a high level, it is preferable to perform the cleaning process using the maintenance liquid multiple times, preferably about 3 to 5 times.

[0069] The liquid can be preliminarily discharged from the liquid deposition device 1200 to the capping unit 1701. The preliminarily discharge is an operation performed to stabilize the discharge state when replacing the liquid deposition device 1200 or performing maintenance on the liquid deposition device, or to normalize the discharge state at any timing, such as before the start of recording, during recording, or after recording. When performing preliminarily discharge with the maintenance device, the cap upstream three-way valve 1704 is opened, the capping unit 1701 is filled with the maintenance liquid, and then a predetermined amount of liquid is preliminarily discharged from the liquid deposition device 1200 into the capping unit 1701. Thereafter, an idle suction operation is performed to send the liquid inside the capping unit 1701 and in the flow path together with the maintenance liquid to the waste liquid tanks 1611 and 1631. If necessary, a flow path cleaning process may be performed in the same manner as described above, in which the cap upstream three-way valve 1704 is opened, the capping unit 1701 is filled with the maintenance liquid, and then an idle suction operation is performed in the same manner to send the maintenance liquid to the waste liquid tanks 1611 and 1631.

[0070] (Capping of liquid application device) The cap leaving operation of the liquid applying device will be described with reference to FIG. 6 and FIG. 8. When the recording operation is completed and no recording is performed for a certain period of time, the liquid applying device 1200 preferably caps the discharge port surface to suppress evaporation in order to suppress adhesion of the liquid in the flow path. The liquid applying device 1200 can be abutted against the capping unit 1701 shown in FIG. 6 to be capped. Before the capping unit 1701 is abutted against the capping unit 1701, the cap upstream three-way valve 1704 shown in FIG. 8 is opened to fill the capping unit 1701 with the maintenance liquid. Thereafter, the liquid applying device 1200 is abutted against the capping unit 1701 to cap it, thereby effectively suppressing adhesion of the liquid in the flow path of the liquid applying device 1200. Even if the capping state continues for a certain period of time, if the liquid applying device 1200 has a liquid circulation mechanism (not shown) in the flow path, the liquid can be stably discharged from the initial stage of resuming recording by the liquid circulation operation in the flow path in the recording preparation operation.

[0071] (Cleaning unit configuration) FIG. 9 is an enlarged perspective view of the dashed line portion shown in FIG. 7, and shows the configuration of a cleaning unit 1801 arranged in a cleaning tray 1800. The cleaning unit 1801 is configured with a maintenance liquid applying device 1850, a liquid removing device 1860, and a negative pressure applying device 1870. The liquid removing device 1860 is configured with a wiper blade 1861 formed of a flexible material such as urethane rubber. FIG. 9 shows an example in which two wiper blades are arranged, but the size and number of wiper blades can be set in consideration of the structure and removal performance of the discharge port surface of the liquid applying device 1200. The negative pressure applying device 1870 is formed of a flexible member 1871, and it is preferable to select a material that can efficiently remove liquid, bubbles, etc. by negative pressure when it comes into contact with the discharge port surface 1207 of the liquid applying device 1200.

[0072] 10A to 10C are schematic diagrams showing a configuration of a maintenance liquid deposition device 1850. FIG. 10A is a perspective view showing the maintenance liquid deposition device 1850. FIG. 10B is a cross-sectional view of the maintenance liquid deposition device 1850 shown in FIG. 10A taken along line AA. FIG. 10C is a cross-sectional view of the maintenance liquid deposition device 1850 shown in FIG. 10A taken along line BB. The maintenance liquid deposition device 1850 has a flexible maintenance liquid deposition member 1851. The maintenance liquid deposition device 1850 also has a maintenance liquid deposition member holder 1852 that holds the maintenance liquid deposition member 1851 and has a flow path formed therein for supplying the maintenance liquid to the inside of the maintenance liquid deposition member 1851. The maintenance liquid deposition device 1850 also has a maintenance liquid deposition member cover 1853 that covers the maintenance liquid deposition member 1851. The maintenance liquid deposition member 1851 is held between the maintenance liquid deposition member holder 1852 and the maintenance liquid deposition member cover 1853. 10B, a maintenance liquid supply tube 1854 is connected to the maintenance liquid application member holder 1852. The maintenance liquid supplied from the maintenance liquid supply tube 1854 passes through the maintenance liquid application member holder 1852, and is applied to the discharge port surface 1207 by the maintenance liquid application member 1851. The maintenance liquid application device 1850 also has a biasing member 1855, and while the maintenance liquid is being applied to the discharge port surface 1207, the maintenance liquid application member 1851 is pressed against the discharge port surface 1207. The maintenance liquid application device 1850 is attached to the cleaning tray 1800 by a support portion 1857.

[0073] As shown in FIGS. 10A to 10C, the maintenance liquid application member 1851 has a notch in a part of the surface that contacts the ejection port surface 1207. The maintenance liquid application member 1851 has a surface 1851a (first surface) on the upstream side (+Y direction) and a surface 1851c (third surface) on the downstream side (-Y direction) with respect to the application direction of the maintenance liquid, and also has a surface 1851b (second surface) that intersects with the first surface 1851a. When applying the maintenance liquid to the ejection port surface 1207, the first surface 1851a on the upstream side with respect to the application direction of the maintenance liquid and the second surface 1851b that intersects with the first surface 1851a come into contact with the ejection port surface 1207 and are pressed against it. At this time, a gap 1856 is formed between the third surface 1851c on the downstream side with respect to the application direction of the maintenance liquid and the ejection port surface 1207. In the illustrated example, the contact length of the first surface 1851a with the ejection port surface 1207 is longer than the contact length of the second surface 1851b with the ejection port surface 1207, making it easier for the maintenance liquid application member 1851 to conform to the surface shape of the ejection port surface 1207.

[0074] 10B, a first surface 1851a on the upstream side in the direction in which the maintenance liquid is applied, which contacts the ejection port surface 1207, is formed to be thinner than a base portion 1851d thereof. As shown in FIG. 10C, a second surface 1851b that intersects with the first surface 1851a on the upstream side in the direction in which the maintenance liquid is applied, is formed to be thinner than a base portion 1851e thereof. With these configurations, the tip of the maintenance liquid application member 1851 is thin and easily deformed. Therefore, when the maintenance liquid application member 1851 is pressed against the ejection port surface 1207 having projections and recesses, it is possible for the maintenance liquid application member 1851 to follow the projections and recesses of the ejection port surface 1207.

[0075] 11 is a schematic diagram showing the positional relationship between the liquid deposition device and the cleaning unit. In this example, a state in which a maintenance liquid deposition device 1850, a liquid removal device 1860, and a negative pressure application device 1870 are in contact with the discharge port surface 1207 of the liquid deposition device 1200 is shown. The maintenance liquid deposition device 1850, the liquid removal device 1860, and the negative pressure application device 1870 are each configured to be able to come into contact with or separate from the discharge port surface 1207. Therefore, each of these can be swept in the longitudinal direction of the liquid deposition device 1200 to deposit maintenance liquid, remove the liquid or a mixture of the maintenance liquid by suction, and wipe the liquid deposition device 1200.

[0076] The cleaning process of the discharge port surface 1207 of the liquid deposition device 1200 will be described. As an example of efficient cleaning, FIG. 12 shows a schematic diagram of an example of the cleaning operation of the liquid deposition device 1200. The present invention is not limited to this method. First, a maintenance liquid deposition device 1850 is swept in a state in which it is in contact with the liquid deposition device 1200, so that the maintenance liquid is deposited on the discharge port surface 1207 and the first protective member 1224 (FIG. 12(a)). Next, a liquid removal device 1860 is swept in a state in which it is in contact with the discharge port surface 1207 and the first protective member 1224, so that the liquid adhering to the discharge port surface 1207 of the liquid deposition device 1200 together with the previously deposited maintenance liquid is wiped off (FIG. 12(b)). By sweeping the negative pressure applying device 1870 while it is in contact with the discharge port surface 1207 of the liquid applying device 1200, it is possible to remove liquid that has solidified near the discharge ports present on the discharge port surface 1207 and to remove bubbles within the flow paths (FIG. 12(c)). The steps in FIGS. 12(a) to 12(c) may be performed in this order, or each step may be performed in parallel.

[0077] Furthermore, when the liquid removing device 1860 is swept while in contact with the ejection port surface 1207 and the first protective member 1224 to wipe off liquid and the like adhering to the ejection port surface 1207, the sweeping direction of the liquid removing device 1860 may be either the +Y direction or the -Y direction in Fig. 7. Similarly, when the negative pressure applying device 1870 is swept while in contact with the ejection port surface 1207 to remove solidified liquid present on the ejection port surface 1207, the sweeping direction of the negative pressure applying device 1870 may be either the +Y direction or the -Y direction in Fig. 7.

[0078] Also, it is preferable that the liquid applying device 1200 has a protective member (hereinafter, also referred to as "second protective member") for protecting the discharge port surface 1207 of the discharge element substrate 1203. That is, it is preferable that the liquid applying device 1200 has a second protective member for protecting the discharge port surface 1207. The second protective member can have an opening corresponding to a discharge port array in which a plurality of discharge ports 1204 are arranged in a predetermined direction. Specifically, a second protective member having a rectangular opening corresponding to the discharge port array is bonded to the discharge port surface 1207 by an adhesive. With such a configuration, when the recording medium 1100 floats up during transportation, the second protective member plays a role of suppressing contact between the recording medium 1100 and the discharge element substrate 1203, and damage to the liquid applying device 1200 can be suppressed. Therefore, it is preferable that the second protective member has sufficient mechanical strength, and for example, a metal material such as stainless steel or aluminum, silicon, or alumina can be suitably used as a material.

[0079] The second protective member has rectangular openings formed therein corresponding to the rows of ejection ports. The openings can be formed to correspond to any number of rows of ejection ports, but it is preferable that one second protective member has a plurality of openings. It is preferable that one opening is formed for one row of ejection ports.

[0080] It is also preferable that the length of the opening of the second protective member in the direction substantially intersecting with the ejection port array direction is 250 μm or more and less than the interval between adjacent ejection port arrays, and the thickness of the second protective member is less than 50 μm. This allows the maintenance device 1600 of the recording device to more suitably recover the liquid on the ejection port surface 1207 of the liquid deposition device 1200 when the maintenance device 1600 comes into contact with the liquid deposition device 1200 during maintenance.

[0081] (Operation for recovering adhesion of ink flow path of liquid application device) The operation of the maintenance device for recovering ink flow paths, such as the nozzles of the liquid deposition device 1200, from adhesion due to ink will be described mainly with reference to FIG.

[0082] First, ink in the flow path of the supply system and the liquid deposition device 1200 (see FIG. 2) in FIG. 5 is discharged. Specifically, the supply path into which the ink circulated to the sub-tank 1503 enters is separated from the sub-tank 1503, and the supply path is connected to a container for discharging the ink in the supply system (not shown). The first circulation pump (high pressure side) 1501, the first circulation pump (low pressure side) 1502, the sub-tank 1503, and the second circulation pump 1505 are operated to discharge the ink in the supply system including the sub-tank 1503. Next, the capping unit 1701 shown in FIG. 6 is brought into contact (capped) with the discharge element substrate 1203 of the liquid deposition device 1200 shown in FIG. 2, and the negative pressure applying device 1870 generates a negative pressure in the discharge element substrate 1203 to discharge the ink in the discharge element substrate 1203. The operation of discharging the ink by generating a negative pressure is called suction.

[0083] Next, the supply system and the flow path of the liquid deposition device 1200 are filled with maintenance liquid, and the remaining ink is mixed with the maintenance liquid and discharged. Specifically, the main tank 1504 is filled with maintenance liquid, and the refill pump 1506 is operated to move the maintenance liquid to the sub-tank 1503. Subsequently, the first circulation pump (high pressure side) 1501, the first circulation pump (low pressure side) 1502, the sub-tank 1503, and the second circulation pump 1505 are operated. As a result, the maintenance liquid is spread throughout the entire supply system, and the ink in the supply system connected to the above-mentioned supply path is discharged to a container for discharging the ink. Next, the capping unit 1701 is brought into contact with (caps) the discharge element substrate 1203 of the liquid deposition device 1200, and the negative pressure applying device 1870 generates negative pressure in the discharge element substrate 1203. As a result, the mixture of the remaining ink and the maintenance liquid in the discharge element substrate 1203 is sucked and discharged.

[0084] Next, the supply system and the ink flow path of the liquid deposition device 1200 are filled with the maintenance liquid again, and the supply path is filled with the maintenance liquid. Specifically, the connected supply path and the container for discharging the ink of the supply system are separated, and the supply path and the sub-tank 1503 are reconnected. The main tank 1504 is filled with the maintenance liquid, and the refill pump 1506 is operated to move the maintenance liquid to the sub-tank 1503. Subsequently, the first circulation pump (high pressure side) 1501, the first circulation pump (low pressure side) 1502, the sub-tank 1503, and the second circulation pump 1505 are operated to distribute the maintenance liquid throughout the entire supply system. Furthermore, the capping unit 1701 is abutted (capped) against the ejection element substrate 1203 with the maintenance liquid filled therein, and is left in this state. The leaving condition may be, for example, one day to one month in an environment with a temperature of 10° C. to 60° C. and a relative humidity of 10% to 80%.

[0085] Next, the maintenance liquid in the supply system and the ink flow path of the liquid deposition device 1200 is discharged. Specifically, the supply path into which the ink circulated to the subtank 1503 enters is separated from the subtank 1503, and the supply path is connected to a container for discharging the ink in the supply system (not shown). The first circulation pump (high pressure side) 1501, the first circulation pump (low pressure side) 1502, and the second circulation pump 1505 are operated to discharge the maintenance liquid in the supply system including the subtank 1503. Next, the capping unit 1701 is brought into contact with (caps) the ejection element substrate 1203 of the liquid deposition device 1200, and the negative pressure is generated in the ejection element substrate 1203 by the negative pressure application device 1870, thereby discharging the maintenance liquid in the ejection element substrate 1203.

[0086] Next, ink is filled again into the ink flow path of the supply system and the liquid deposition device 1200, and it is confirmed whether or not the ink has been restored from the adhesion. Specifically, the connected supply path is separated from the container for discharging the ink in the supply system, and the supply path is reconnected to the sub-tank 1503. The main tank 1504 is filled with ink, and the refill pump 1506 is operated to move the ink to the sub-tank 1503. Subsequently, the first circulation pump (high pressure side) 1501, the first circulation pump (low pressure side) 1502, the sub-tank 1503, and the second circulation pump 1505 are operated to distribute the ink throughout the entire supply system. Next, the capping unit 1701 is brought into contact with (caps) the ejection element substrate 1203 of the liquid deposition device 1200, and the negative pressure application device 1870 generates negative pressure in the ejection element substrate 1203. This allows the adhesion and maintenance liquid remaining in the ink flow path of the liquid deposition device to be discharged. Subsequently, an image that can confirm the ejection state of all ejection ports is recorded using an inkjet recording device having the configuration shown in Fig. 1, and adhesion recovery is confirmed. Examples of suction conditions include the following: A negative pressure of -20 kPa to -200 kPa is maintained for 3 to 60 seconds. This suction operation is performed, for example, 1 to 20 times. The timing for recording an image that can confirm the ejection state of the openings of all the liquid deposition devices can be arbitrary.

[0087] [Heating section] As shown in Fig. 1, the heating section 2000 is configured to include a heating device 2100 and a transport member 2200. The recording medium 1100, to which the reaction liquid and ink have been applied and an image has been recorded, is heated by the heating device 2100 while being transported by the transport member 2200, thereby evaporating and drying the liquid components of the image. It is preferable to further include a drying step between the ink application step and the fixing step, in which the recording medium to which the ink has been applied is heated in a non-contact manner to dry the ink. By including such a drying step, deformation (cockling and curling) of the recording medium 1100 can be effectively suppressed.

[0088] The heating device 2100 may have any configuration as long as it can heat the recording medium 1100, and various conventionally known devices such as a hot air dryer and a heater can be used. Among them, the use of a non-contact heater such as an electric heating wire or infrared heater is preferable from the standpoint of safety and energy efficiency. In addition, if a mechanism for blowing hot air with a built-in fan for spraying heated gas onto the recording medium 1100 is used, the drying efficiency can be easily improved.

[0089] Regarding the method of heating, the recording medium 1100 may be heated from the side (recording surface (front side)) to which the reaction liquid and the ink are applied, or from the back side, or from both sides. The conveying member 2200 may be provided with a heating function. FIG. 1 shows the conveying member 2200 using a conveying belt, but a spur, conveying drum, or the like may be used as long as it has the function of conveying the recording medium 1100. From the viewpoint of suppressing deformation of the recording medium 1100 due to heating, it is preferable to have a configuration in which the recording medium 1100 is conveyed while being in close contact with the conveying member 2200 by blowing air from the heating unit 2000, or to have a mechanism for fixing the recording medium to the conveying member 2200. Specifically, a method of providing a hole in the conveying member 2200 and fixing the recording medium 1100 by suction from the back side, a method of forming the conveying member 2200 from an appropriate material, and fixing the recording medium 1100 by electrostatic adsorption, etc. can be mentioned.

[0090] The heating temperature is preferably set so as to quickly evaporate the liquid components and not to over-dry the recording medium 1100 in terms of suppressing deformation of the recording medium. The temperature of the drying means can be set so that the recording medium reaches a desired temperature, taking into consideration the conveying speed and the environmental temperature. Specifically, the temperature of the drying means (such as hot air) is preferably set to 40°C or higher and 100°C or lower, and more preferably 60°C or higher and 80°C or lower. In addition, when the recording medium 1100 is heated by blowing heated gas, the wind speed is preferably set to 1 m / s or higher and 100 m / s or lower. The temperature of the wind such as the hot air can be measured using a K-type thermocouple thermometer. A specific measuring device can be, for example, the product name "AD-5605H" (manufactured by A&D).

[0091] Fig. 13 is a schematic diagram showing another example of the heating section. Here, the difference from the heating section shown in Fig. 1 and described above will be described. The heating section 2000 shown in Fig. 13 includes a first heating device 2101 and a second heating device 2102, and a first conveying member 2201 and a second conveying member 2202 arranged opposite the first heating device 2101 and the second heating device 2102, respectively.

[0092] The first conveying member 2201 does not have a mechanism for sucking and fixing the recording medium 1100. The recording medium 1100 is pressed against the first conveying member 2201 by hot air from the first heating device 2101 to convey the recording medium 1100. This allows the recording medium 1100 to be transferred with high precision from the conveying member 1300 (FIG. 1) to the first conveying member 2201, and from the first conveying member 2201 to the second conveying member 2202. Furthermore, it is possible to reduce conveyance deviations caused by slight differences in conveying speed between the conveying member 1300 (FIG. 1) and the first conveying member 2201. On the other hand, a conveying belt having holes that can pass gas is used as the second conveying member 2202, and the recording medium 1100 is conveyed while being fixed to the second conveying member 2202 by a suction mechanism (not shown).

[0093] An air knife 2300 is disposed between the transport member 1300 (FIG. 1) and the first transport member 2201, between the first transport member 2201 and the second transport member 2202, and between the second transport member 2202 and the transport member 3200 (FIG. 1). The air pressure from the air knife 2300 prevents the leading edge of the transported recording medium 1100 from floating up. This makes it possible to prevent the leading edge of the recording medium 1100 from colliding with the first heating device 2101, the second heating device 2102, and the fixing member 3100 (FIG. 1), and to suppress the occurrence of transport failure.

[0094] The first heating device 2101 and the second heating device 2102 can have the same configuration as the above-mentioned heating device 2100. The temperatures of the first heating device 2101 and the second heating device 2102 and the wind speed when blowing heated gas for heating may be the same or different. Furthermore, heating may be performed from the first conveying member 2201 and the second conveying member 2202 as necessary.

[0095] [Fixing section] As shown in FIG. 1, the fixing unit 3000 is a contact-type heating and pressurizing mechanism having a fixing member 3100 as a fixing belt such as an endless belt and a conveying member 3200. In the fixing unit 3000, the recording medium 1100 is conveyed by the conveying member 3200, and the fixing member 3100 is brought into contact with the recording medium 1100 under pressure, and the liquid such as the reaction liquid or ink applied to the recording medium 1100 is heated. In this way, an image can be fixed on the recording medium 1100. From the recording medium 1100 on which an image has been recorded, the liquid components of the reaction liquid or ink permeate the recording medium 1100 or evaporate by passing through the heating unit 2000, and then the image is fixed in the fixing unit 3000, completing the image. By heating and pressurizing the recording medium 1100 sandwiched between the fixing member 3100 and the conveying member 3200, the image of the recording medium 1100 and the fixing member 3100 come into close contact with each other, and the image is fixed on the recording medium 1100. When a liquid such as ink containing resin particles and coloring material is used, the resin particles are softened and form a film mainly by heating in the fixing unit 3000 , and the coloring material can be bound onto the recording medium 1100 .

[0096] The fixing member 3100 may be heated by providing a heat source such as a halogen heater inside a roller that drives the fixing member 3100 as a fixing belt. Alternatively, a heat source such as an infrared heater may be provided at a location separate from the fixing member 3100. These methods may be combined. If necessary, the conveying member 3200 may be heated. The temperature of the fixing member 3100 may be set so that the surface of the recording medium has a desired temperature, taking into account the conveying speed and the environmental temperature. Specifically, the temperature of the fixing member 3100 is preferably 50° C. or higher and 120° C. or lower, and more preferably 60° C. or higher and 110° C. or lower. The temperature of the contact-type heating and pressing mechanism (fixing member 3100) and the surface temperature of the recording medium immediately after passing through the contact-type heating and pressing mechanism can both be measured using a radiation thermometer. The radiation thermometer may be installed near the end (terminal end) of the contact-type heating and pressing mechanism. A specific example of the radiation thermometer is a product name "Radiation Thermometer IT-545S" (manufactured by Horiba, Ltd.).

[0097] When the ink contains resin particles, if the temperature of the fixing member 3100 is set to a temperature equal to or higher than the glass transition temperature of the resin particles in the ink, the resin particles soften and are more likely to form a film, improving the scratch resistance of the image. When the ink contains wax particles, it is preferable to set the temperature of the fixing member 3100 lower than the melting point of the wax that constitutes the wax particles. This makes it easier for the wax, which is prevented from melting, to remain on the surface of the image, improving the scratch resistance of the image.

[0098] The nip pressure of the fixing member 3100 and the conveying member 3200, i.e., the pressure applied to the recording medium when it passes through the contact-type heating and pressing mechanism, is preferably from 10 Pa to 1,000 Pa, and more preferably from 10 Pa to 500 Pa. Also, it is particularly preferably from 10 Pa to 400 Pa. The time required for the recording medium to pass through the contact-type heating and pressing mechanism (nip time) is preferably from 0.25 seconds to 5.0 seconds, more preferably from 0.5 seconds to 4.0 seconds, and particularly preferably from 1.0 seconds to 3.0 seconds.

[0099] FIG. 14 is a schematic diagram showing another example of the fixing unit. Here, the difference from the fixing unit shown in FIG. 1 and described above will be described. The fixing unit 3000 shown in FIG. 14 is a contact type heating and pressurizing mechanism including a plurality of fixing rollers 3101 and a plurality of conveying members 3201 arranged opposite to these fixing rollers 3101. An image is fixed on the recording medium 1100 to which a liquid such as ink has been applied by passing between the fixing rollers 3101 and the conveying members 3201. The degree of image fixing on the recording medium can be adjusted by controlling the number of fixing rollers 3101 and the conveying members 3201, the nip time of the recording medium by these, the temperature, the pressure, and the like.

[0100] [Cooling section] The cooling section 4000 is configured to include a cooling member 4100 and a conveying member 4200 (FIG. 1). The cooling section 4000 cools the recording medium 1100, which has been heated to a high temperature after passing through the heating section 2000 and the fixing section 3000. The cooling member 4100 may have any configuration as long as it can cool the recording medium 1100, and methods such as air cooling and water cooling can be used. Among them, blowing unheated gas is preferable in terms of safety and energy efficiency. In addition, if a fan is built in to inject gas onto the recording medium 1100 and a mechanism for blowing air is used, it is easy to improve cooling efficiency. The temperature of the cooling means can be set so that the image on the recording medium has a desired temperature, taking into account the conveying speed and the environmental temperature. Specifically, the temperature of the cooling means (such as air blowing) is preferably 20° C. or higher and 60° C. or lower, and more preferably 25° C. or higher and 50° C. or lower. When cooling by blowing gas, the wind speed is preferably 1 m / s or higher and 100 m / s or lower. By setting such conditions, it is possible to suppress deformation of the recording medium 1100 loaded in the paper discharge unit 6000 described later and image sticking (blocking).

[0101] [Inverted part] When performing double-sided recording, the recording medium 1100 is inverted using the inversion unit 5000 (FIG. 1). The recording medium 1100 with an image recorded on its recording surface (front side) passes through the cooling unit 4000, is branched and transported, and is inverted by the inversion device 5100. The inverted recording medium 1100 is transported to the paper feeder 1400 of the recording unit 1000 with liquid applied to its back side (the side opposite to the recording surface (front side)).

[0102] [Paper output section] After the image is recorded, the recording medium 1100 is stored in a paper discharge section 6000 (FIG. 1). After single-sided or double-sided recording is performed, the recording medium 1100 passes through the cooling section 4000, is transported by a transport member 6100, and is finally stored in a stacked state in a recording medium storage section 6200. Two or more recording medium storage sections 6200 may be provided to store different recorded materials, etc.

[0103] <Maintenance fluid> Next, the aqueous maintenance liquid of the present invention will be described in detail. The maintenance liquid can be used in the ink set, recording method, and recording device described above. This maintenance liquid contains a water-soluble compound represented by the following general formula (1). The maintenance liquid can contain one or more of the water-soluble compounds represented by general formula (1). R 1 -XR 2 (1) In the general formula (1), X represents a sulfonyl group or a sulfoxide group, and R 1 and R 2 do not combine with each other to form a ring, and each independently represent an alkyl group which may be substituted with a hydroxyl group.

[0104] (Water-soluble compound represented by general formula (1)) R in general formula (1) 1 and R 2 The alkyl group which may be substituted with a hydroxyl group represented by may be either a straight chain or a branched chain. The number of carbon atoms in the alkyl group is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 to 3. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, and a tert-butyl group. Among these, R in the general formula (1) is particularly preferred. 1 and R 2 is preferably a methyl group or an ethyl group. 1 and R 2 By using a maintenance liquid containing a water-soluble compound represented by general formula (1) where each of the groups independently represents a methyl group or an ethyl group, the adhesion recovery properties of the ink flow path of the liquid application device are more likely to be improved.

[0105] Examples of the water-soluble compound in which X in the general formula (1) is a sulfonyl group include dimethyl sulfone, diethyl sulfone, dipropyl sulfone, ethyl methyl sulfone, isopropyl methyl sulfone, and bishydroxyethyl sulfone. Examples of the water-soluble compound in which X in the general formula (1) is a sulfoxide group include dimethyl sulfoxide, diethyl sulfoxide, and dipropyl sulfoxide. One or more of these can be contained in the maintenance liquid. Among these, the water-soluble compound represented by the general formula (1) in which X in the general formula (1) is a sulfoxide group is preferred because it tends to improve the adhesion recovery of the ink flow path of the liquid application device.

[0106] In addition, X in the general formula (1) is a sulfonyl group, and R 1 and R 2 Water-soluble compounds such as sulfolane in which the groups are linked to form a ring tend to have strong interactions with groups such as phenyl groups in the epoxy resin composition, resulting in poor wettability.

[0107] The content (mass %) of the water-soluble compound represented by general formula (1) in the aqueous maintenance liquid is preferably 10% by mass or more and 90% by mass or less, and more preferably 20% by mass or more and 80% by mass or less, based on the total mass of the maintenance liquid. When the content of the water-soluble compound represented by general formula (1) in the maintenance liquid is 10% by mass or more, more preferably 20% by mass or more, the adhesion recovery of the ink flow path of the liquid application device is likely to be improved. On the other hand, when the content of the water-soluble compound represented by general formula (1) in the maintenance liquid is 90% by mass or less, more preferably 80% by mass or less, the contact with the components in the liquid application device is likely to be improved.

[0108] (aqueous medium) The maintenance liquid is an aqueous maintenance liquid containing at least water as an aqueous medium. The maintenance liquid may contain water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent. As the water, deionized water or ion-exchanged water is preferably used. The water content (mass %) in the maintenance liquid is preferably 5% by mass or more and 90% by mass or less, and more preferably 20% by mass or more and 80% by mass or less, based on the total mass of the maintenance liquid. When the water content in the maintenance liquid is 5% by mass or more, the liquid contact with the components in the liquid application device is likely to be improved. On the other hand, when the water content in the maintenance liquid is 90% by mass or less, the adhesion recovery of the ink flow path of the liquid application device is likely to be improved.

[0109] (Other Ingredients) In addition to the above-mentioned components, the maintenance liquid may contain various additives, such as an antifoaming agent, a surfactant, a pH adjuster, a viscosity adjuster, a rust inhibitor, a preservative, an antifungal agent, an antioxidant, and an antireducing agent, as necessary.

[0110] (Physical properties of maintenance fluid) The maintenance liquid is an aqueous maintenance liquid applied to the inkjet method. Therefore, from the viewpoint of reliability, it is preferable to appropriately control the physical property values. Specifically, the static surface tension of the maintenance liquid at 25°C is preferably 20 mN / m or more and 65 mN / m or less. In addition, the viscosity of the maintenance liquid at 25°C is preferably 1.0 mPa·s or more and 10.0 mPa·s or less. The pH of the maintenance liquid at 25°C is preferably 3.0 or more and 10.0 or less.

[0111] <Reaction solution> The recording method of the present invention may further include a reaction liquid application step of applying an aqueous reaction liquid containing a reactant that reacts with the aqueous ink to the recording medium before the ink application step. The ink set may further include an aqueous reaction liquid in addition to the aqueous ink and the aqueous maintenance liquid, and the recording device may further include an aqueous reaction liquid. Each component used in the reaction liquid will be described in detail below.

[0112] [Reactants] The reaction liquid reacts with the ink when it comes into contact with the ink, and aggregates the components in the ink (components having anionic groups, such as resins, surfactants, and self-dispersing pigments), and contains a reactant. The presence of the reactant can destabilize the state of the components having anionic groups in the ink when the ink and the reactant come into contact with each other on the recording medium, and promote the aggregation of the ink. Examples of the reactant include cationic components such as polyvalent metal ions and cationic resins, and organic acids. The reactant may be used alone or in combination of two or more.

[0113] Examples of polyvalent metal ions constituting polyvalent metal salts include Ca. 2+ , Cu 2+ , Ni 2+ , Mg 2+ , Sr 2+ , B.A. 2+ , and Zn 2+ Divalent metal ions such as Fe 3+ , Cr 3+ , Y 3+ , and Al 3+ In order to add a polyvalent metal ion to the reaction solution, a water-soluble polyvalent metal salt (which may be a hydrate) formed by combining a polyvalent metal ion with an anion can be used. Examples of the anion include Cl. - , Br - , I - , ClO - , ClO2 - , ClO3 - , ClO4 - , NO2 - , NO3- , SO4 2- , CO3 2- , HCO3 - , PO4 3- , HPO4 2- , and H2PO4 - Inorganic anions such as HCOO - , (COO - )2, COOH(COO - ), CH3COO - , CH3CH(OH)COO - , C2H4(COO - )2, C6H5COO - , C6H4(COO - )2, and CH3SO3 - In the case where a polyvalent metal ion is used as a reactant, the content (mass%) of the polyvalent metal salt in the reaction solution is preferably 1.0 mass% or more and 20.0 mass% or less based on the total mass of the reaction solution. In this specification, when the polyvalent metal salt is a hydrate, the "content (mass%) of the polyvalent metal salt" in the reaction solution means the "content (mass%) of the anhydride of the polyvalent metal salt" excluding water as the hydrate.

[0114] The reaction liquid containing an organic acid has a buffering ability in the acidic range (less than pH 7.0, preferably pH 2.0 to 5.0), and thus efficiently converts the anionic groups of the components present in the ink into an acid form and causes them to aggregate. Examples of the organic acid include monocarboxylic acids and salts thereof, such as formic acid, acetic acid, propionic acid, butyric acid, benzoic acid, glycolic acid, lactic acid, salicylic acid, pyrrole carboxylic acid, furan carboxylic acid, picolinic acid, nicotinic acid, thiophene carboxylic acid, levulinic acid, and coumaric acid; dicarboxylic acids and salts and hydrogen salts thereof, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, itaconic acid, sebacic acid, phthalic acid, malic acid, and tartaric acid; tricarboxylic acids and salts and hydrogen salts thereof, such as citric acid and trimellitic acid; and tetracarboxylic acids and salts and hydrogen salts thereof, such as pyromellitic acid. When an organic acid is used as the reactant, the content (mass %) of the organic acid in the reaction liquid is preferably 1.0 mass % or more and 50.0 mass % or less based on the total mass of the reaction liquid.

[0115] Examples of cationic resins include resins having a structure of primary to tertiary amines and resins having a structure of quaternary ammonium salts. Specific examples include resins having a structure of vinylamine, allylamine, vinylimidazole, vinylpyridine, dimethylaminoethyl methacrylate, ethyleneimine, guanidine, diallyldimethylammonium chloride, and alkylamine-epichlorohydrin condensate. In order to increase the solubility in the reaction solution, the cationic resin may be used in combination with an acidic compound or the cationic resin may be subjected to a quaternary treatment. When a cationic resin is used as a reactant, the content (mass%) of the cationic resin in the reaction solution is preferably 0.1 mass% or more and 10.0 mass% or less based on the total mass of the reaction solution.

[0116] [Aqueous medium] The reaction liquid is an aqueous reaction liquid containing at least water as an aqueous medium. The aqueous medium used in the reaction liquid can be the same as the aqueous medium that can be contained in the ink described later. The aqueous medium used in the reaction liquid can contain the water-soluble organic solvent that can be contained in the ink described later. The content (mass%) of the water-soluble organic solvent in the reaction liquid is preferably 1.0 mass% or more and 45.0 mass% or less based on the total mass of the reaction liquid. The water-soluble organic solvent preferably contains a specific water-soluble hydrocarbon compound described later. The content (mass%) of the water-soluble hydrocarbon compound in the reaction liquid is preferably 1.0 mass% or more and 20.0 mass% or less based on the total mass of the reaction liquid. In addition, the content (mass%) of water in the reaction liquid is preferably 50.0 mass% or more and 95.0 mass% or less based on the total mass of the reaction liquid.

[0117] [Other ingredients] The reaction liquid may contain various other components as necessary, including the same components as those that can be contained in the ink, which will be described later.

[0118] [Physical properties of reaction solution] The reaction liquid is an aqueous reaction liquid applied to the inkjet method. Therefore, from the viewpoint of reliability, it is preferable to appropriately control the physical property values. Specifically, the surface tension of the reaction liquid at 25°C is preferably 20 mN / m or more and 60 mN / m or less. In addition, the viscosity of the reaction liquid at 25°C is preferably 1.0 mPa·s or more and 10.0 mPa·s or less. The pH of the reaction liquid at 25°C is preferably 5.0 or more and 9.5 or less, and more preferably 6.0 or more and 9.0 or less.

[0119] <Ink> The ink used in the ink set, recording method, and recording apparatus described above is a water-based ink for inkjet recording, which contains coloring materials and resin particles. Each component of the ink will be described in detail below.

[0120] [Colorant] The ink contains a coloring material. A pigment or a dye can be used as the coloring material. The content (mass %) of the coloring material in the ink is preferably 0.5% by mass or more and 15.0% by mass or less, and more preferably 1.0% by mass or more and 10.0% by mass or less, based on the total mass of the ink.

[0121] Specific examples of pigments include inorganic pigments such as carbon black and titanium oxide, and organic pigments such as azo, phthalocyanine, quinacridone, isoindolinone, imidazolone, diketopyrrolopyrrole, dioxazine, etc. The pigments may be used alone or in combination of two or more.

[0122] As the dispersion method of the pigment, a resin-dispersed pigment using a resin as a dispersant, a self-dispersed pigment in which a hydrophilic group is bonded to the pigment particle surface, etc. can be used. In addition, a resin-bonded pigment in which an organic group containing a resin is chemically bonded to the pigment particle surface, and a microcapsule pigment in which the surface of the pigment particle is coated with a resin, etc. can be used. It is also possible to use a combination of pigments with different dispersion methods among these. In particular, it is preferable to use a resin-dispersed pigment in which a resin as a dispersant is physically adsorbed on the pigment particle surface, rather than a resin-bonded pigment or a microcapsule pigment.

[0123] As the resin dispersant for dispersing the pigment in the aqueous medium, it is preferable to use one that can disperse the pigment in the aqueous medium by the action of anionic groups. As the resin dispersant, a resin having an anionic group can be used, and it is preferable to use a resin as described below, especially a water-soluble resin. The content (mass%) of the pigment in the ink is preferably 0.3 times or more and 10.0 times or less in mass ratio to the content (mass%) of the resin dispersant.

[0124] As the self-dispersing pigment, an anionic group such as a carboxylic acid group, a sulfonic acid group, or a phosphonic acid group can be used, which is bonded to the particle surface of the pigment directly or via another atomic group (-R-). The anionic group may be either an acid type or a salt type, and when it is a salt type, it may be either a partially dissociated state or a completely dissociated state. When the anionic group is a salt type, examples of the cation that serves as the counter ion include an alkali metal cation, ammonium, and organic ammonium. Specific examples of the other atomic group (-R-) include a linear or branched alkylene group having 1 to 12 carbon atoms; an arylene group such as a phenylene group or a naphthylene group; a carbonyl group; an imino group; an amide group; a sulfonyl group; an ester group; and an ether group. In addition, it may be a group that is a combination of these groups.

[0125] The dye preferably has an anionic group. Specific examples of the dye include azo, triphenylmethane, (aza)phthalocyanine, xanthene, and anthrapyridone dyes. The dye may be used alone or in combination of two or more. The coloring material is preferably a pigment, and more preferably a resin-dispersed pigment or a self-dispersed pigment.

[0126] [Resin particles] The ink contains resin particles. By using the ink containing the resin particles, an image with improved abrasion resistance can be recorded. The form of the resin particles may be a single-layer resin particle, or may be a resin particle having a so-called core-shell structure having a core part and a shell part covering the core part.

[0127] The content (mass%) of the resin particles in the ink is preferably 1.0% by mass or more and 15.0% by mass or less, more preferably 1.0% by mass or more and 12.0% by mass or less, based on the total mass of the ink. When the content of the resin particles is 1.0% by mass or more, the scratch resistance of the image is likely to be improved. On the other hand, when the content of the resin particles is 15.0% by mass or less, the color development of the image is likely to be improved. Examples of the form of the resin contained in the resin particles include block copolymers, random copolymers, graft copolymers, and combinations thereof. The resin particles may be used alone or in combination of two or more types. The resin particles may also contain color materials (dyes, pigments, invisible color materials that develop color due to fluorescence, etc.).

[0128] [Composition of Resin Particles] The resin particles include at least one selected from the group consisting of acrylic resin particles, styrene resin particles, urethane resin particles, and polyester resin particles. Among them, acrylic resin particles and urethane resin particles are preferred, and acrylic resin particles composed of units derived from (meth)acrylic acid or (meth)acrylate are more preferred.

[0129] [Acrylic Resin Particles] The acrylic resin particles contain units derived from a (meth)acrylic acid ester. Examples of monomers ((meth)acrylic acid esters) that form units derived from (meth)acrylic acid esters by polymerization include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, lauryl (meth)acrylate, and hexadecyl (meth)acrylate; monocyclic (meth)acrylates such as cyclopropyl (meth)acrylate, cyclohexyl (meth)acrylate, cyclooctyl (meth)acrylate, and cyclodecyl (meth)acrylate; bicyclic (meth)acrylates such as isobornyl (meth)acrylate and norbornyl (meth)acrylate; tricyclic (meth)acrylates such as adamantyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate; and nonionic hydrophilic group-containing (meth)acrylates such as methoxy(mono-, di-, tri-, and poly)ethylene glycol (meth)acrylate. The monomers may be used alone or in combination of two or more.

[0130] The acrylic resin particles may contain units (other units) other than the above-mentioned units derived from (meth)acrylic acid esters, as long as the effect of the present invention is not impaired. The other units include units derived from monomers having at least one polymerizable functional group such as an ethylenically unsaturated bond in the molecule other than (meth)acrylic acid esters, and preferably units derived from ethylenically unsaturated monomers. Such other units include hydrophilic units, hydrophobic units, and units derived from crosslinking agents.

[0131] The hydrophilic unit is a unit having a hydrophilic group such as an anionic group. Examples of the anionic group include a carboxylic acid group, a phenolic hydroxy group, and a phosphoric acid ester group. As a monomer that forms a unit having a hydrophilic group by polymerization, a monomer that has an anionic group and one polymerizable functional group such as an ethylenically unsaturated bond in the molecule is preferable, and an ethylenically unsaturated monomer having an anionic group is more preferable. One of such monomers may be used alone, or two or more may be used in combination. Examples of the monomer that forms a hydrophilic unit by polymerization include an acidic monomer having a carboxylic acid group such as (meth)acrylic acid, itaconic acid, maleic acid, and fumaric acid, and an anionic monomer such as an anhydride or salt of these acidic monomers. Examples of the cation that constitutes the salt of the acidic monomer include ions of lithium, sodium, potassium, ammonium, and organic ammonium.

[0132] The hydrophobic unit is a unit that does not have a hydrophilic group such as an anionic group. Examples of the hydrophobic unit include a unit having an aromatic group, a unit having a cyano group (also called a nitrile group), and other hydrophobic units.

[0133] As the monomer that forms a unit having an aromatic group by polymerization, it is preferable that the monomer has an aromatic group and has one polymerizable functional group such as an ethylenically unsaturated bond in the molecule, and more preferably an ethylenically unsaturated monomer having an aromatic group. Therefore, it is more preferable that the unit having an aromatic group is a unit derived from an ethylenically unsaturated monomer having an aromatic group. Examples of the aromatic group include a phenyl group, a biphenyl group, a naphthyl group, an anthryl group, a carbazole group, a triazinyl group, and a pyrenyl group, which may have a substituent. Examples of the substituent include an alkyl group and a halogen atom. Among these aromatic groups, an unsubstituted phenyl group and a phenyl group substituted with at least one substituent selected from the group consisting of an alkyl group and a halogen atom are preferable. Examples of monomers that form a unit having an aromatic group by polymerization include 2-vinylnaphthalene, 9-vinylanthracene, 9-vinylcarbazole, phenyl(meth)acrylate, benzyl(meth)acrylate, 2-phenoxyethyl(meth)acrylate, 2,4-diamino-6-((meth)acryloyloxy)ethyl-1,3,5-triazine, 2-naphthyl(meth)acrylate, 9-anthryl(meth)acrylate, and (1-pyrenyl)methyl(meth)acrylate. These may be used alone or in combination of two or more.

[0134] As the monomer that forms a unit having a cyano group by polymerization, one that has a cyano group and one polymerizable functional group such as an ethylenically unsaturated bond in the molecule is preferred, and an ethylenically unsaturated monomer that has a cyano group is more preferred. Therefore, the unit having a cyano group is more preferably a unit derived from an ethylenically unsaturated monomer that has a cyano group. Examples of the monomer that forms a unit having a cyano group by polymerization include acrylonitrile, methacrylonitrile, chloroacrylonitrile, and 2-cyanoethyl (meth)acrylate. These may be used alone or in combination of two or more.

[0135] The monomer that forms the other hydrophobic unit by polymerization is preferably one having one polymerizable functional group such as an ethylenically unsaturated bond in the molecule other than the monomer that forms the hydrophobic unit described above, and more preferably an ethylenically unsaturated monomer. The monomer that forms the other hydrophobic unit can be, for example, an alkene such as ethylene or propylene. These may be used alone or in combination of two or more.

[0136] Examples of crosslinking agents that form units derived from the crosslinking agent by polymerization include compounds having two or more polymerizable functional groups, such as ethylenically unsaturated bonds, in the molecule.Examples of such crosslinking agents include diene compounds such as butadiene and isoprene; 1,4-butanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, (mono-, di-, tri-, poly-)ethylene glycol di(meth)acrylate, (mono-, di-, tri-, poly-)propylene glycol di(meth)acrylate, (mono-, di-, tri-, poly-)tetramethylene glycol di(meth)acrylate, ethylene oxide modified bisphenol A di(meth)acrylate, 2-hydroxy-3-(meth)acrylate, acryloyloxypropyl methacrylate, propoxylated ethoxylated bisphenol A di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, 9,9-bis(4-(2-(meth)acryloyloxyethoxy)phenyl)fluorene, tricyclodecane dimethanol di(meth)acrylate, 1,10-decane diol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, ethoxylated poly Bifunctional (meth)acrylates such as propylene glycol di(meth)acrylate and glycerin di(meth)acrylate; tris(2-(meth)acryloyloxyethyl)isocyanurate, trimethylolpropane tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, propoxylated glyceryl tri(meth)acrylate, trifunctional (meth)acrylates such as di(2-(meth)acryloyloxyethyl)isocyanurate, ethoxylated isocyanuric acid tri(meth)acrylate, ε-caprolactone-modified tris-(2-(meth)acryloyloxyethyl)isocyanurate, and ethylene oxide-modified trimethylolpropane tri(meth)acrylate; tetrafunctional (meth)acrylates such as ditrimethylolpropane tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, and pentaerythritol tetra(meth)acrylate; and divinylbenzene.These may be used alone or in combination of two or more.

[0137] The crosslinking agent preferably has a molecular weight of more than 200, more preferably has a molecular weight of more than 300, and particularly preferably has a molecular weight of 400 or more. The crosslinking agent is preferably a compound having two ethylenically unsaturated bonds in the molecule. By using a compound having two ethylenically unsaturated bonds in the molecule as a crosslinking agent, the aggregation of resin particles caused by excessive crosslinking is suppressed, and resin particles with a more uniform particle size can be obtained. Among the compounds having two ethylenically unsaturated bonds in the molecule, divinylbenzene and ethylene glycol di(meth)acrylate are more preferable.

[0138] Examples of crosslinking agents having a glycidyl group include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, sorbitol polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane polyglycidyl ether, and neopentyl glycol diglycidyl ether.

[0139] [Styrene-based resin particles] The styrene-based resin particles include a unit having a styrene structure. As a monomer that forms a unit having a styrene structure by polymerization, one having a styrene structure and one polymerizable functional group such as an ethylenically unsaturated bond in the molecule is preferable, and a styrene-based ethylenically unsaturated monomer is more preferable. Therefore, the unit having a styrene structure is more preferably a unit derived from a styrene-based ethylenically unsaturated monomer, that is, a styrene-based monomer. Examples of the styrene-based monomer include styrene, 4-methylstyrene, p-fluorostyrene, p-chlorostyrene, and α-methylstyrene. One of these may be used alone, or two or more may be used in combination.

[0140] The styrene-based resin particles may contain units (other units) other than the above-mentioned units having a styrene structure, as long as the effect of the present invention is not impaired. Examples of the other units include units derived from monomers (preferably ethylenically unsaturated monomers) having at least one polymerizable functional group such as an ethylenically unsaturated bond in the molecule other than the monomers forming the units having a styrene structure. Examples of the other units in the styrene-based resin particles include units derived from (meth)acrylic acid esters, hydrophilic units, hydrophobic units, and units derived from crosslinking agents, all of which are listed in the description of the acrylic resin particles. The styrene-based resin particles may contain one or more of these other units. In this specification, resin particles containing units derived from (meth)acrylic acid esters in addition to the above-mentioned units having a styrene structure are referred to as styrene-based resin particles.

[0141] [Method of producing acrylic resin particles and styrene resin particles] The acrylic resin particles and the styrene resin particles can be produced according to a conventionally known method, such as an emulsion polymerization method, a mini-emulsion polymerization method, a seed polymerization method, or a phase inversion emulsification method.

[0142] A surfactant can be used when producing acrylic resin particles or styrene resin particles. It is preferable to produce resin particles in the presence of a surfactant, since the particle size and shape of the resulting resin particles are likely to be stable. As the surfactant used when producing resin particles, a reactive surfactant is preferable, since it is difficult to peel off from the resin particles. Since the reactive surfactant is difficult to peel off from the resin particles, it is difficult to affect the physical properties of the ink, and the ejection characteristics are unlikely to deteriorate.

[0143] As the reactive surfactant, it is preferable to use a compound in which a polymerizable functional group such as an acryloyl group, a methacryloyl group, a maleyl group, a vinyl group, or an allyl group is bonded to the inside or end of a molecule composed of a hydrophilic part and a hydrophobic part. Examples of the hydrophilic part include polyoxyalkylene chains such as an ethylene oxide chain and a propylene oxide chain. Examples of the hydrophobic part include structures such as alkyl, aryl, and combinations thereof. The hydrophilic part and the hydrophobic part may be bonded via a linking group such as an ether group. As the reactive surfactant, those having a molecular weight of more than 200 are preferable, those having a molecular weight of more than 300 are more preferable, and those having a molecular weight of 400 or more are particularly preferable.

[0144] Examples of reactive surfactants include polyoxyethylene nonylpropenyl phenyl ether, polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate, polyoxyethylene-1-(allyloxymethyl) alkyl ether ammonium sulfate, α-hydro-ω-(1-alkoxymethyl-2-(2-propenyloxy)ethoxy)-poly(oxy-1,2-ethanediyl)), α-[1-[(allyloxy)methyl]-2-(nonylphenoxy)ethyl]-ω-hydroxypolyoxyethylene, α-sulfo-ω-(1-alkoxymethyl-2-(2-propenyloxy)ethoxy)-poly(oxy-1,2-ethanediyl) Examples of the alkoxy group include bis(oxy)-poly(oxy-1,2-ethanediyl)ammonium salt, 2-sodium sulfoethyl methacrylate, bis(polyoxyethylene polycyclic phenyl ether) methacrylate sulfate, alkoxypolyethylene glycol methacrylate, alkoxypolyethylene glycol maleate, polyoxyalkylene alkenyl ether, polyoxyalkylene alkenyl ether ammonium sulfate, vinyl ether alkoxylate, alkylaryl sulfosuccinate, polyoxyalkylene methacrylate sulfate, unsaturated phosphate, etc. These may be used alone or in combination of two or more.

[0145] [Urethane-based resin particles] The proportion (mass%) of the urethane resin in the resin forming the urethane resin particles is preferably 90.0 mass% or more based on the total mass of the urethane resin particles, and may be 100.0 mass%. In other words, it is preferable that the urethane resin particles are substantially formed only of the urethane resin. As the urethane resin particles, commercially available products may be used.

[0146] The urethane resins generally used in aqueous inkjet inks are synthesized using at least a polyisocyanate and a component that reacts with it (a polyol or a polyamine), and a crosslinking agent or a chain extender are also used as necessary.

[0147] (Polyisocyanate) In this specification, "polyisocyanate" means a compound having two or more isocyanate groups in the molecule. Examples of polyisocyanates include aliphatic and aromatic polyisocyanates. Examples of aliphatic polyisocyanates include polyisocyanates having a chain structure such as tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, and 2,2,4-trimethylhexamethylene diisocyanate; and polyisocyanates having a cyclic structure such as isophorone diisocyanate, hydrogenated xylylene diisocyanate, and 1,4-cyclohexane diisocyanate. Examples of aromatic polyisocyanates include tolylene diisocyanate and xylylene diisocyanate. Among them, aliphatic polyisocyanates are preferred. The ratio (mol%) of units derived from polyisocyanate in the resin forming the urethane-based resin particles is preferably 10.0 mol% or more and 80.0 mol% or less.

[0148] (Polyols, polyamines) As the component that becomes a unit constituting the urethane resin by the reaction with the polyisocyanate, polyol or polyamine can be used. In this specification, "polyol" means a compound having two or more hydroxyl groups in the molecule. Examples of polyols include polyols without acid groups such as polyether polyols, polyester polyols, and polycarbonate polyols; polyols with acid groups; and the like. In addition, in this specification, "polyamine" means a compound having two or more "amino groups, imino groups" in the molecule. The ratio (mol %) of units derived from polyols and polyamines in the resin that forms the urethane resin particles is preferably 10.0 mol % or more and 80.0 mol % or less.

[0149] Examples of polyols that do not have an acid group include polyether polyols such as addition polymers of alkylene oxides and polyols; glycols such as (poly)alkylene glycol; and the like. Examples of polyester polyols include acid esters. Examples of polycarbonate polyols include alkanediol-based polycarbonate diols. The number average molecular weight of the polyol that does not have an acid group is preferably 400 or more and 4,000 or less. Examples of polyols that do not have an acid group include polyether polyols and polycarbonate polyols, and polyether polyols are more preferred. Examples of polyols that have an acid group include polyols that have a carboxylic acid group such as dimethylol acetic acid, dimethylol propionic acid, and dimethylol butanoic acid.

[0150] Examples of polyamines include monoamines having multiple hydroxyl groups such as dimethylolethylamine, bifunctional polyamines such as ethylenediamine, isophoronediamine, and xylylenediamine, and trifunctional or higher polyamines such as diethylenetriamine, triethylenetetramine, and tetraethylenepentamine. For convenience, compounds having multiple hydroxyl groups and one "amino group, imino group" are also listed as "polyamines".

[0151] (Cross-linking agents, chain extenders) The urethane resin may have a unit derived from a crosslinking agent or a chain extender. The crosslinking agent is usually used when synthesizing a prepolymer. The chain extender is usually used when extending the chain of a prepolymer that has been synthesized in advance. The crosslinking agent or the chain extender can be appropriately selected from water, the above-mentioned polyisocyanate, polyol, polyamine, etc., depending on the purpose of crosslinking or chain extension.

[0152] [Method for producing urethane resin particles] The urethane resin particles can be produced, for example, by synthesizing a urethane resin and then granulating it. The urethane resin can be obtained, for example, by reacting a polyisocyanate with a compound that reacts therewith (polyol, polyamine) in the presence of an organic solvent. The synthesized urethane resin is preferably granulated by a dispersion method, a phase inversion (emulsion) method, or the like, in the presence of a base or the like as necessary.

[0153] [Polyester-based resin particles] A polyester resin usually contains a unit derived from a polyhydric alcohol and a unit derived from a polycarboxylic acid. A structure containing an ester bond (-COO-) and composed of a unit derived from a polyhydric alcohol and a unit derived from a polycarboxylic acid is also referred to as an "ester unit."

[0154] (Polyhydric alcohol) Examples of the polyhydric alcohol include dihydric to tetrahydric polyhydric alcohols. Examples of the polyhydric alcohol include polyhydric alcohols having an aliphatic group, polyhydric alcohols having an aromatic group, and sugar alcohols. Examples of the polyhydric alcohol include dihydric alcohols such as ethylene glycol [1,2-ethanediol], neopentyl glycol [2,2-dimethyl-1,3-propanediol], 1,3-propanediol, 1,4-butanediol, benzenediol, and 2,2-bis(4-hydroxyphenyl)propane [Bisphenol A]; trihydric alcohols such as glycerin, trimethylolethane, and trimethylolpropane; and tetrahydric alcohols such as pentaerythritol. Examples of the polyhydric alcohol include oligomers (low molecular weight polymers having a molecular weight of 1,000 or less). The ratio (mass%) of units derived from polyhydric alcohols in the resin forming the polyester resin particles is preferably 40.0 mass% or more and 60.0 mass% or less.

[0155] As the polyhydric alcohol, it is preferable to use a polyhydric alcohol having an aromatic group. Among them, it is preferable to use bisphenol A. In addition, polyhydric alcohols having an aromatic group and polyhydric alcohols having an aliphatic group may be used in combination. As the polyhydric alcohols having an aliphatic group, it is preferable to use a polyhydric alcohol having a linear or branched aliphatic group having 1 to 6 carbon atoms. Among them, ethylene glycol and neopentyl glycol are preferable.

[0156] (Polycarboxylic Acid) Examples of the polycarboxylic acid constituting the unit derived from the polycarboxylic acid include divalent to tetravalent polycarboxylic acids. Examples of the polycarboxylic acid include polycarboxylic acids having an aliphatic group; polycarboxylic acids having an aromatic group; and nitrogen-containing polycarboxylic acids. Examples of the polycarboxylic acid include dicarboxylic acids such as glutaric acid, adipic acid, terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid; tricarboxylic acids such as trimellitic acid; and tetracarboxylic acids such as ethylenediaminetetraacetic acid. Examples of the polycarboxylic acid include oligomers (low molecular weight polymers having a molecular weight of 1,000 or less). The proportion (mass%) of the unit derived from the polycarboxylic acid in the polyester resin forming the polyester resin particles is preferably 40.0 mass% or more and 60.0 mass% or less.

[0157] As the polycarboxylic acid, it is preferable to use a polycarboxylic acid having an aromatic group. Among them, it is preferable to use adipic acid, terephthalic acid, isophthalic acid, and trimellitic acid. It is also preferable to use a plurality of polycarboxylic acids. Specifically, it is preferable to use a plurality of dicarboxylic acids. Among them, it is preferable to use terephthalic acid and isophthalic acid.

[0158] [Method for producing polyester resin particles] The polyester resin particles can be produced, for example, by synthesizing a polyester resin and then granulating it. The polyester resin can be obtained, for example, by reacting a polyhydric alcohol with a polycarboxylic acid (esterification reaction). If necessary, a so-called transesterification reaction may be carried out in which either a polyhydric alcohol or a polycarboxylic acid is added to cleave a part of the ester bond. It is preferable to carry out the transesterification reaction by adding a polycarboxylic acid having three or more valences (especially, trimellitic acid is preferable). The synthesized polyester resin is preferably made into an appropriate form by pressing, pulverizing, or the like, and then granulated by a dispersion method, a phase inversion (emulsion) method, or the like.

[0159] [Properties of resin particles] In this specification, the term "resin particles" means that when the resin is neutralized with an alkali equivalent to the acid value, it is present in an aqueous medium in a state in which it forms particles whose particle diameter can be measured by a dynamic light scattering method. Whether or not it is a resin particle can be determined according to the following method. First, a liquid (resin solid content: 10 mass%) containing a resin neutralized with an alkali (sodium hydroxide, potassium hydroxide, etc.) equivalent to the acid value is prepared. Next, the prepared liquid is diluted 10 times (volume basis) with pure water to prepare a sample solution. Then, when the particle diameter of the resin in the sample solution is measured by a dynamic light scattering method, if particles having a particle diameter are measured, the resin can be determined to be a resin particle. The measurement conditions at this time can be, for example, SetZero: 30 seconds, number of measurements: 3 times, and measurement time: 180 seconds. In addition, as a particle size distribution measurement device, a particle size analyzer using a dynamic light scattering method (for example, product name "UPA-EX150", manufactured by Nikkiso) can be used. Of course, the particle size distribution measurement device and measurement conditions used are not limited to those described above.

[0160] The glass transition temperature (°C) of the resin forming the resin particles is preferably 40°C or higher and 110°C or lower, more preferably 45°C or higher and 90°C or lower. When the glass transition temperature of the resin forming the resin particles is 40°C or higher, the blocking resistance of the image is likely to be increased. On the other hand, when the glass transition temperature of the resin forming the resin particles is 110°C or lower, the binding property of the resin particles to the recording medium is strong, and the scratch resistance of the image is likely to be increased. In addition, the glass transition temperature (°C) of the resin forming the resin particles is preferably 80°C or lower, more preferably 50°C or higher and 80°C or lower. The glass transition temperature of the resin forming the resin particles can be measured using a differential scanning calorimeter (for example, the product name "DSC Q1000" manufactured by TA instruments, etc.).

[0161] The acid value of the resin forming the resin particles is preferably 5 mgKOH / g or more and 100 mgKOH / g or less, more preferably 5 mgKOH / g or more and 50 mgKOH / g or less. The weight average molecular weight of the resin forming the resin particles is preferably 1,000 or more and 2,000,000 or less. The volume average particle diameter of the resin particles measured by dynamic light scattering (cumulative 50% particle diameter D of the volume-based particle size distribution) is preferably 1,000 or more and 2,000,000 or less. 50 ) is preferably 50 nm or more and 500 nm or less, and more preferably 50 nm or more and 200 nm or less. The cumulative 50% particle diameter of the volume-based particle size distribution of the resin particles is the diameter of the particle that is 50% of the total volume of the measured particles when integrated from the small particle diameter side in the particle diameter integration curve. The volume average particle diameter of the resin particles can be measured using the dynamic light scattering particle size analyzer and measurement conditions described above.

[0162] [Method of verifying resin particles] The composition of the resin particles can be verified according to the following methods (i) and (ii). Below, a method for extracting resin particles from ink and analyzing and verifying them will be described, but resin particles extracted from an aqueous dispersion or the like can also be analyzed and verified in the same manner.

[0163] (i) Extraction of resin particles Density gradient centrifugation can be used to separate and extract resin particles from ink that contains them. Among density gradient centrifugation methods, density gradient sedimentation velocity separates and extracts resin particles based on the difference in sedimentation coefficient of components. Also, among density gradient centrifugation methods, density gradient sedimentation equilibrium separates and extracts resin particles based on the difference in density of components.

[0164] (ii) Analysis of the units (monomers) that make up the resin The resin particles to be used as a sample may be in the form of a dispersion liquid. Alternatively, resin particles may be dried to form a film to be used as a sample. The sample resin is subjected to elemental analysis by a combustion method. Separately, the resin fractionated by the acid decomposition (addition of hydrofluoric acid) method or the alkali fusion method is pretreated, and then the inorganic components are quantitatively analyzed by inductively coupled plasma atomic emission spectrometry. In addition, the types and ratios of the units (monomers) that make up the resin can be known by nuclear magnetic resonance (NMR) spectroscopy.

[0165] [Water-soluble resin] The ink may contain a water-soluble resin that is soluble in an aqueous medium. The water-soluble resin may be added to the ink (i) to stabilize the dispersion state of the pigment, i.e., as a resin dispersant or its auxiliary, or (ii) to improve various properties of the recorded image.

[0166] The content (mass%) of the water-soluble resin in the ink is preferably 0.1% by mass or more and 20.0% by mass or less, more preferably 0.5% by mass or more and 15.0% by mass or less, based on the total mass of the ink. Examples of the form of the water-soluble resin include block copolymers, random copolymers, graft copolymers, and combinations thereof. The water-soluble resin may be used alone or in combination of two or more kinds.

[0167] [Composition of Water-Soluble Resin] Examples of the water-soluble resin include acrylic resins, urethane resins, olefin resins, etc. Among them, acrylic resins and urethane resins are preferred, and acrylic resins composed of units derived from (meth)acrylic acid or (meth)acrylate are more preferred.

[0168] The acrylic resin preferably has a hydrophilic unit and a hydrophobic unit as constituent units. Among them, a resin having a hydrophilic unit derived from (meth)acrylic acid and a hydrophobic unit derived from at least one of a monomer having an aromatic ring and a (meth)acrylic acid ester monomer is preferred. In particular, a resin having a hydrophilic unit derived from (meth)acrylic acid and a hydrophobic unit derived from at least one of styrene and α-methylstyrene is preferred. These resins are easily interacted with pigments, and therefore can be suitably used as a resin dispersant for dispersing pigments.

[0169] The hydrophilic unit is a unit having a hydrophilic group such as an anionic group. The hydrophilic unit can be formed, for example, by polymerizing a hydrophilic monomer having a hydrophilic group. Specific examples of the hydrophilic monomer having a hydrophilic group include acidic monomers having a carboxylic acid group such as (meth)acrylic acid, itaconic acid, maleic acid, and fumaric acid, and anionic monomers such as anhydrides and salts of these acidic monomers. Examples of cations constituting the salts of acidic monomers include ions of lithium, sodium, potassium, ammonium, and organic ammonium. The hydrophobic unit is a unit not having a hydrophilic group such as an anionic group. The hydrophobic unit can be formed, for example, by polymerizing a hydrophobic monomer not having a hydrophilic group such as an anionic group. Specific examples of the hydrophobic monomer include monomers having an aromatic ring such as styrene, α-methylstyrene, and benzyl (meth)acrylate; and (meth)acrylic acid ester monomers such as methyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

[0170] The urethane resin can be obtained by reacting, for example, polyisocyanate with a polyol. In addition, a chain extender may be further reacted with the urethane resin. Examples of the olefin resin include polyethylene and polypropylene.

[0171] [Properties of water-soluble resin] In this specification, "a resin is water-soluble" means that when the resin is neutralized with an alkali equivalent to the acid value, the resin is present in an aqueous medium in a state in which it does not form particles whose particle size can be measured by a dynamic light scattering method. Whether or not a resin is water-soluble can be determined according to the following method. First, a liquid (resin solid content: 10 mass%) containing a resin neutralized with an alkali (sodium hydroxide, potassium hydroxide, etc.) equivalent to the acid value is prepared. Next, the prepared liquid is diluted 10 times (volume basis) with pure water to prepare a sample solution. Then, when the particle size of the resin in the sample solution is measured by a dynamic light scattering method, if no particles having a particle size are measured, the resin can be determined to be water-soluble. The measurement conditions at this time can be, for example, SetZero: 30 seconds, number of measurements: 3 times, and measurement time: 180 seconds. In addition, a particle size analyzer using a dynamic light scattering method (for example, the product name "UPA-EX150", manufactured by Nikkiso) can be used as a particle size distribution measuring device. Of course, the particle size distribution measuring device and the measuring conditions are not limited to those described above.

[0172] The acid value of the water-soluble resin is preferably 100 mgKOH / g or more and 250 mgKOH / g or less, and the weight average molecular weight of the water-soluble resin is preferably 3,000 or more and 15,000 or less.

[0173] [Wax particles] The ink may contain particles formed of wax (wax particles). By using an ink containing wax particles, an image with improved abrasion resistance can be recorded. In this specification, the wax may be a composition containing components other than wax, or the wax itself. The wax particles may be dispersed by a dispersant such as a surfactant or a resin. The wax may be used alone or in combination of two or more kinds. The content (mass %) of the wax particles in the ink is preferably 0.1 mass % or more and 10.0 mass % or less, and more preferably 1.0 mass % or more and 5.0 mass % or less, based on the total mass of the ink.

[0174] In the narrow sense, wax is an ester of a water-insoluble higher monohydric or dihydric alcohol and a fatty acid, and includes animal waxes and vegetable waxes, but does not include oils and fats. In the broad sense, wax includes high melting point fats, mineral waxes, petroleum waxes, and blends and modified products of various waxes. In the present invention, any wax in the broad sense can be used without particular restrictions. Wax in the broad sense can be classified into natural waxes, synthetic waxes, blends thereof (blended waxes), and modified products thereof (modified waxes).

[0175] Examples of natural waxes include animal waxes such as beeswax, spermaceti, and wool wax (lanolin); vegetable waxes such as wood wax, carnauba wax, sugarcane wax, palm wax, candelilla wax, and rice wax; mineral waxes such as montan wax; and petroleum waxes such as paraffin wax, microcrystalline wax, and petrolatum. Examples of synthetic waxes include hydrocarbon waxes such as Fischer-Tropsch wax and polyolefin wax (e.g., polyethylene wax and polypropylene wax). The blended wax is a mixture of the above-mentioned various waxes. The modified wax is a wax obtained by subjecting the above-mentioned various waxes to a modification treatment such as oxidation, hydrogenation, alcohol modification, acrylic modification, and urethane modification. One of the above waxes may be used alone, or two or more may be used in combination. The wax is preferably at least one selected from the group consisting of microcrystalline wax, Fischer-Tropsch wax, polyolefin wax, paraffin wax, and modified or blended products thereof. Among them, a blend of multiple types of wax is more preferable, and a blend of a petroleum wax and a synthetic wax is particularly preferable.

[0176] The wax is preferably solid at room temperature (25°C). The melting point (°C) of the wax is preferably 40°C or higher and 120°C or lower, and more preferably 50°C or higher and 100°C or lower. The melting point of the wax can be measured in accordance with the test method described in 5.3.1 (melting point test method) of JIS K2235:1991 (petroleum wax). In the case of microcrystalline wax, petrolatum, and a mixture of multiple types of wax, the test method described in 5.3.2 can be used to measure more accurately. The melting point of the wax is easily affected by characteristics such as molecular weight (the higher the molecular weight, the higher the melting point), molecular structure (the higher the melting point if the chain is straight, and the lower the melting point if there is branching), crystallinity (the higher the crystallinity, the higher the melting point), and density (the higher the crystallinity, the higher the melting point). Therefore, by controlling these characteristics, it is possible to obtain a wax having a desired melting point. The melting point of the wax in the ink can be measured in accordance with the above test method, for example, after the ink is subjected to ultracentrifugation, the wax separated is washed and dried.

[0177] [Aqueous medium] The ink used in the recording method of the present invention is an aqueous ink containing at least water as an aqueous medium. The ink can contain water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent. As the water, deionized water or ion-exchanged water is preferably used. The content (mass%) of water in the aqueous ink is preferably 50.0 mass% or more and 95.0 mass% or less based on the total mass of the ink. In addition, the content (mass%) of the water-soluble organic solvent in the aqueous ink is preferably 2.0 mass% or more and 40.0 mass% or less based on the total mass of the ink. As the water-soluble organic solvent, any of those usable for inkjet inks, such as alcohols, (poly)alkylene glycols, glycol ethers, nitrogen-containing solvents, and sulfur-containing solvents, can be used. The water-soluble organic solvent may be used alone or in combination of two or more.

[0178] [Water-soluble hydrocarbon compounds] The water-soluble organic solvent contained in the ink preferably contains a specific water-soluble hydrocarbon compound. This water-soluble hydrocarbon compound is a compound having a hydrocarbon chain having three or more carbon atoms substituted with two or more hydrophilic groups selected from the group consisting of hydroxyl groups, amino groups, and anionic groups. However, the hydrocarbon chain may be interrupted by a sulfonyl group or an ether group. When the hydrocarbon chain has three or four carbon atoms, the hydrophilic group contains an anionic group, or the hydrocarbon chain is interrupted by a sulfonyl group.

[0179] In the present invention, a hydrocarbon compound that is dissolved in water at 25°C at the content of the compound in the ink is considered to be "water-soluble". In other words, the solubility in water at 25°C is greater than the content in the ink. The fact that the hydrocarbon chain is interrupted by a sulfonyl group or an ether group means that a sulfonyl group (-S(=O)2-) or an ether group (-O-) is present in the middle of the hydrocarbon chain. Water-soluble hydrocarbon compounds have hydrogen-bonding groups such as hydroxyl groups, amino groups, anionic groups, sulfonyl groups, and ether groups. Therefore, by using an ink containing this hydrocarbon compound, cockling and curling of a recording medium on which an image is recorded can be suppressed. General hydrocarbon compounds having a hydrocarbon chain with a relatively small number of carbon atoms (3 or 4) tend to have a small molecular weight and a low vapor pressure. However, since the above water-soluble hydrocarbon compounds have anionic groups of hydrogen bonds or the hydrocarbon chain is interrupted by a sulfonyl group, they are difficult to evaporate due to inter- or intra-molecular interactions, and remain between fibers to suppress cockling and curling. The content (mass %) of the water-soluble hydrocarbon compound in the ink is preferably 1.0 mass % or more and 20.0 mass % or less based on the total mass of the ink.

[0180] The number of carbon atoms in the hydrocarbon chain constituting the water-soluble hydrocarbon compound is preferably from 3 to 50, and more preferably from 3 to 10. Examples of the anionic group include a sulfonic acid group and a carboxylic acid group. Specific examples of water-soluble hydrocarbon compounds include alkanediols such as 1,5-pentanediol and 1,6-hexanediol; amino acids such as alanine, β-alanine, trimethylglycine, amidosulfuric acid (also known as sulfamic acid), aminomethanesulfonic acid, taurine (also known as 2-aminoethanesulfonic acid), carbamic acid, glycine, aspartic acid, glutamic acid, sulfanilic acid, or salts of the above-mentioned acids, phenylalanine, leucine, isoleucine, threonine, tryptophan, valine, methionine, lysine, and arginine; sulfonyl compounds such as bis(2-hydroxyethyl)sulfone; alkylene glycols such as triethylene glycol, tetraethylene glycol, tripropylene glycol, and polyethylene glycols having a number average molecular weight of about 200 to 1,000; and sugars such as sorbitol, D-sorbitol, xylitol, trehalose, fructose, and D(+)-xylose. The water-soluble hydrocarbon compounds may be used alone or in combination of two or more.

[0181] [Other ingredients] The ink may contain various other components as necessary. Examples of other components include various additives such as defoamers, surfactants, pH adjusters, viscosity adjusters, rust inhibitors, preservatives, antifungal agents, antioxidants, and reduction inhibitors. However, it is preferable that the ink does not contain a reactant to be contained in the reaction liquid.

[0182] [Ink properties] The ink is a water-based ink applied to the inkjet method. Therefore, from the viewpoint of reliability, it is preferable to appropriately control the physical property values. Specifically, the surface tension of the ink at 25°C is preferably 20 mN / m or more and 60 mN / m or less. In addition, the viscosity of the ink at 25°C is preferably 1.0 mPa·s or more and 10.0 mPa·s or less. The pH of the ink at 25°C is preferably 7.0 or more and 9.5 or less, and more preferably 8.0 or more and 9.5 or less. EXAMPLES

[0183] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples without departing from the gist of the invention. "Parts" and "%" used to describe the amounts of components are based on mass unless otherwise specified.

[0184] <Preparation of pigment dispersion> (Pigment dispersion 1) To a solution of 5.00 g of concentrated hydrochloric acid in 5.50 g of water, 1.80 g of 4-amino-1,2-benzenedicarboxylic acid was added at a temperature of 5°C. To the solution obtained above, a solution of 1.80 g of sodium nitrite in 9.00 g of water was added while stirring in an ice bath to maintain the temperature at 10°C or less. After stirring for 15 minutes, the specific surface area was 254 m 2 6.00 g of carbon black with a DBP oil absorption of 180 mL / 100 g was added and mixed. After stirring for 15 minutes, the resulting slurry was filtered with filter paper (standard filter paper No. 2, manufactured by Advantec), and the carbon black was thoroughly washed with water and dried in an oven at a temperature of 110°C. Water was added to the resulting carbon black to obtain pigment dispersion 1 with a pigment (carbon black) content of 10.0%. Pigment dispersion 1 contained a self-dispersing pigment with -C6H3-(COONa)2 groups bonded to the particle surface.

[0185] (Pigment dispersion 2) A styrene-ethyl acrylate-acrylic acid copolymer (resin 1) with an acid value of 150 mgKOH / g and a weight average molecular weight of 8,000 was prepared. 20.0 parts of resin 1 were neutralized with potassium hydroxide in an amount equimolar to the acid value, and an appropriate amount of pure water was added to prepare an aqueous solution of resin 1 with a resin (solid content) content of 20.0%. 10.0 parts of pigment (CI Pigment Blue 15:3), 15.0 parts of the aqueous solution of resin 1, and 75.0 parts of pure water were mixed to obtain a mixture. The obtained mixture and 200 parts of zirconia beads with a diameter of 0.3 mm were placed in a batch-type vertical sand mill (manufactured by Imex) and dispersed for 5 hours while cooling with water. After removing coarse particles by centrifugation, the mixture was pressure-filtered with a cellulose acetate filter (manufactured by Advantec) with a pore size of 3.0 μm to prepare pigment dispersion 2 with a pigment content of 10.0% and a resin dispersant (resin 1) content of 3.0%.

[0186] (Pigment dispersion 3) Pigment dispersion 3 was prepared using the same procedure as for pigment dispersion 2 described above, except that the pigment was changed to CI Pigment Red 122. The pigment content was 10.0% and the resin dispersant (resin 1) content was 3.0%.

[0187] (Pigment Dispersion 4) Pigment dispersion 4 was prepared using the same procedure as for pigment dispersion 2 described above, except that the pigment was changed to CI Pigment Yellow 74. The pigment content was 10.0% and the resin dispersant (resin 1) content was 3.0%.

[0188] (Pigment Dispersion 5) Pigment dispersion 5 was prepared using the same procedure as for pigment dispersion 2 described above, except that the pigment was changed to carbon black. The pigment dispersion 5 had a pigment content of 10.0% and a resin dispersant (resin 1) content of 3.0%.

[0189] <Preparation of resin particles> (Resin particles 1-3, 6, 7) A solution was prepared by mixing 0.2 parts of potassium persulfate and 74.0 parts of ion-exchanged water. In addition, methyl methacrylate (MMA), ethyl methacrylate (EMA), n-butyl methacrylate (nBMA), styrene (St), acrylonitrile (AN), methacrylic acid (MAA), and a reactive surfactant in the amounts shown in Table 1 (breakdown (parts) of charged monomers) were mixed to prepare an emulsion. As the reactive surfactant, a product name "ADEKA REASOAP ER-20" (hereinafter sometimes abbreviated as "ER20"; manufactured by ADEKA; nonionic surfactant; number of moles of ethylene oxide group added: 20) was used. The emulsion was dropped into the solution over 1 hour under a nitrogen atmosphere, polymerized while stirring at 80°C, and then further stirred for 2 hours. After cooling to room temperature, ion-exchanged water and an aqueous potassium hydroxide solution were added to obtain an aqueous dispersion of each single-layer type resin particle with a resin particle content of 25.0%. The cumulative 50% particle diameter (D 50 The cumulative 50% particle diameter (D 50 The methods for measuring the particle diameter (nm) and the glass transition temperature (Tg (°C)) of the resin particles are shown below.

[0190] TIFF2025034262000001.tif54170

[0191] [Cumulative 50% particle size of resin particles based on volume] The aqueous dispersion of resin particles was diluted with pure water to prepare a liquid containing resin particles with a resin particle content of 1.0% as a measurement sample. The cumulative 50% particle diameter (D 50 The measurement conditions were as follows: SetZero: 30 seconds, number of measurements: 3, measurement time: 180 seconds, shape: spherical, refractive index: 1.6.

[0192] [Glass transition temperature of resin particles] A resin sample was prepared by drying an aqueous dispersion of resin particles. A differential scanning calorimeter (trade name "Q200", manufactured by TA Instruments) was used to measure the glass transition temperature (Tg (℃)) of the resin particles by performing two temperature cycles in which the temperature was increased from -70℃ to 180℃ at a rate of 10℃ / min.

[0193] (Resin particles 4, 5) A reaction vessel equipped with a stirrer was set in a hot water bath. 1,178 parts of water was placed in the reaction vessel, and the internal temperature was maintained at 70°C. In addition, methyl methacrylate (MMA), ethyl methacrylate (EMA), n-butyl methacrylate (nBMA), 2-ethylhexyl acrylate (2EHA), methacrylic acid (MAA), and a reactive surfactant in the amounts shown in Table 2 (breakdown (parts) of charged monomers) were mixed to prepare an emulsion for the core part. As the reactive surfactant, a product name "ADEKA REASOAP ER-20" (manufactured by ADEKA, nonionic surfactant, number of moles of ethylene oxide group added: 20) was used. Furthermore, 1.9 parts of potassium persulfate and 659 parts of water were mixed to prepare an aqueous solution 1 of the polymerization initiator. The emulsion for the core part and the aqueous solution 1 of the polymerization initiator were dropped into the reaction vessel in parallel over 60 minutes. After the dropwise addition was completed, the mixture was stirred for an additional 30 minutes to react, thereby synthesizing particles that would become the core parts of the resin particles.

[0194] Next, methyl methacrylate (MMA), ethyl methacrylate (EMA), methacrylic acid (MAA), ethylene glycol dimethacrylate (EDMA), and reactive surfactant in the amounts shown in Table 2 (breakdown (parts) of charged monomers) were mixed to prepare an emulsion for the shell part. As the reactive surfactant, "ADEKA REASOAP ER-20" (manufactured by ADEKA, nonionic surfactant, number of moles of ethylene oxide group added: 20) was used. In addition, 0.1 parts of potassium persulfate and 133 parts of water were mixed to prepare an aqueous solution 2 of the polymerization initiator. The emulsion for the shell part and the aqueous solution 2 of the polymerization initiator were dropped in parallel over 10 minutes into a reaction vessel containing particles that would become the core part. After the dropping was completed, the mixture was stirred at 80°C for 10 minutes to continue the reaction to synthesize the shell part, and each core-shell type resin particle in which the particles that would become the core part were coated with the resin that would become the shell part was synthesized. The ratio of the core part to the shell part during synthesis was the ratio of the amounts shown in the "Charge amount (parts)" in Table 2. Then, ion-exchanged water and an aqueous potassium hydroxide solution were added to obtain an aqueous dispersion of each resin particle with a resin particle content of 25.0%. The cumulative 50% particle diameter (D 50 The volume-based cumulative 50% particle diameter (D 50 The methods for measuring the particle diameter (nm) and the glass transition temperature (Tg (° C.)) of the resin particles are the same as those for the single-layer type resin particles.

[0195] TIFF2025034262000002.tif45170

[0196] (Resin particles 8) As an aqueous dispersion containing urethane-based resin particles, a product called "Superflex 830HS" (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used. The resin content in this aqueous dispersion was 27%. This aqueous dispersion was used as an aqueous dispersion of resin particles 8. The cumulative 50% particle diameter (D 50 The particle diameter (nm) was 10 nm, and the glass transition temperature (Tg(°C)) of the resin particles was 68°C.

[0197] (Resin particles 9) (Preparation of polyester resin) A mixture of 90.0 parts of neopentyl glycol, 10.0 parts of 2,2-bis(4-hydroxyphenyl)propane, 50.0 parts of terephthalic acid, 50.0 parts of isophthalic acid, and 7.6 parts of trimellitic acid was placed in a reaction vessel installed in an autoclave. This mixture was heated at 220°C for 4 hours to carry out an esterification reaction. The temperature was then raised to 240°C, and the pressure was reduced to 13 Pa over 90 minutes. The esterification (dehydration condensation) reaction was continued by maintaining the reduced pressure of 240°C and 13 Pa for 5 hours, and then nitrogen gas was introduced to return to normal pressure. After lowering the temperature to 220°C, a catalyst (tetra-n-butyl titanate) and 2.4 parts of adipic acid were added, and the mixture was heated at 220°C for 2 hours to carry out an ester exchange reaction. The amount of catalyst used was "3 x 10 -4 × total amount of polyvalent carboxylic acid used (mol). Nitrogen gas was then introduced to create a pressurized state, and a sheet-like resin was taken out. The resin taken out was cooled to 25°C and then crushed using a crusher to obtain a polyester resin.

[0198] (Preparation of polyester resin particles) A stirrer (product name "Tornado Stirrer Standard SM-104", manufactured by AS ONE) was set in a beaker with a volume of 2 L. 210 g of the above polyester resin and 390 g of tetrahydrofuran were placed in the beaker, and the components were dissolved by stirring at 25 ° C. Then, a 5.0% aqueous sodium hydroxide solution was added in an amount corresponding to the neutralization rate (mol%) based on the acid value of the polyester resin, and stirred for 30 minutes. Furthermore, 900 g of ion-exchanged water was dropped at a rate of 20 mL / min while stirring at 25 ° C. and a stirring speed of 150 rpm. Then, the temperature was raised to 60 ° C., and tetrahydrofuran and a part of the water were distilled off under reduced pressure. The beaker was placed in a water bath, stirred at 85 ° C. for 1 hour, and heat treatment was performed. The contents were filtered through a 150 mesh (150 gaps per inch) wire mesh, and the content of the resin particles was adjusted. In this way, an aqueous dispersion of resin particles 9 containing a resin that is a polyester resin particle and having a resin content of 25.0% was obtained. The cumulative 50% particle diameter (D 50 The particle diameter (nm) was 100 nm, and the glass transition temperature (Tg (°C)) of resin particle 9 was 64°C.

[0199] <Ink Preparation> Each component (unit: %) shown in Table 3 (Table 3-1 and Table 3-2) was mixed and thoroughly stirred, and then pressure filtered through a cellulose acetate filter (manufactured by Advantec) with a pore size of 3.0 μm to prepare each ink. "Acetylenol E100" is the trade name of a surfactant manufactured by Kawaken Fine Chemicals.

[0200] TIFF2025034262000003.tif63170

[0201] TIFF2025034262000004.tif62170

[0202] <Preparation of maintenance liquid> The components (unit: %) shown in Table 4 (Table 4-1 and Table 4-2) were mixed and thoroughly stirred, and then pressure filtered using a cellulose acetate filter (manufactured by Advantec) with a pore size of 3.0 μm to prepare each maintenance liquid.

[0203] TIFF2025034262000005.tif90170

[0204] TIFF2025034262000006.tif90170

[0205] <Preparation of Liquid Application Apparatus> (Adhesive 1-8) Each adhesive prepared by mixing the epoxy resin and hardener (unit: parts) shown in Table 5 (Table 5-1 and Table 5-2) was applied to the support member 1232 and the first flow path member 1234 of the flow path member 1233 shown in Fig. 3, and they were bonded together. Thereafter, the adhesive was hardened at 100°C for 1 hour to prepare an epoxy resin composition, which was used to bond the members together.

[0206] (Adhesive 9) The urethane-based adhesive shown in Table 5 was applied to the support member 1232 and the first flow path member 1234 of the flow path member 1233 shown in Figure 3, and then the members were bonded together. The adhesive was then cured at 25°C for 24 hours to bond the members together.

[0207] (Adhesive 10) As shown in Table 5, no curing agent was used and only epoxy resin was used, but the members could not be bonded together and a liquid application device could not be produced.

[0208] In addition, "jER825", "jER828", "jER806", "jER630", and "jER171N" in Table 5 are the product names of adhesives manufactured by Mitsubishi Chemical. "EH-5015S" and "EH-5046S" are the product names of adhesives manufactured by ADEKA. "PN23J" is the product name of an adhesive manufactured by Ajinomoto Fine-Techno, "TMTA-C" is the product name of an adhesive manufactured by New Japan Chemical, and "UT100B" is the product name of an adhesive manufactured by Cemedine.

[0209] TIFF2025034262000007.tif79170

[0210] TIFF2025034262000008.tif78170

[0211] <Evaluation> The adhesive, ink, and maintenance liquid were combined as shown on the left side of Tables 6 and 7, and an image was recorded on a recording medium using the inkjet recording apparatus 100 having the configuration shown in Fig. 1. The amount of ink applied when recording a solid image was 10 g / m 2 The heating section 2000 uses non-contact heating with hot air, with a hot air speed of 2 m / sec, a hot air temperature of 80° C., and a heating time of 1.5 seconds. In the fixing section 3000, the temperature was 85° C., the nip pressure was 20 Pa, and the nip time was 2 seconds. The recorded images were evaluated as follows. In this embodiment, the evaluation criteria for each item below were set with "A" and "B" as acceptable levels, and "C" as unacceptable levels. The evaluation results are shown on the right side of Tables 6 and 7.

[0212] (Abrasion resistance) A 2 cm x 2 cm solid image with 100% ink printing duty was printed on a recording medium, high-quality paper (product name "OK Prince High Quality", Nippon Paper Industries Co., Ltd., basis weight 104.7 g / m 2 In this embodiment, an image recorded under the condition that one ink droplet of 3.0 ng is applied to a unit area of ​​1 / 1200 inch x 1 / 1200 inch is defined as having a print duty of 100%.

[0213] The recorded image was left for 24 hours in an environment of 25°C and 55% relative humidity, and then a friction test was performed using a Gakushin type abrasion tester (manufactured by Imoto Manufacturing Co., Ltd.), which is a testing machine conforming to JIS L0849, with a load of 100g and one or three strokes. A recording medium of the same type as the recording medium on which the image was recorded was attached to the friction element as a recording medium for evaluation. The solid image after the friction test was visually observed, and the abrasion resistance of the image was evaluated according to the following evaluation criteria. A: The solid image was not erased even after three round trips. B: After one round trip, the solid image was not scraped off, but after three round trips, the solid image was scraped off and the white background of the recording medium was visible. C: After one round trip, the solid image was scraped off and the white background of the recording medium was visible.

[0214] (Adhesion recovery) An image in which the ejection state of all the ejection ports can be confirmed was recorded and confirmed using an inkjet recording apparatus having the configuration shown in Fig. 1 in which the liquid application apparatus was filled with ink. After that, the liquid application apparatus was left in an environment of a temperature of 30°C and a relative humidity of 10% without being capped with the capping unit 1701 in Fig. 6, and then an image in which the ejection state can be confirmed was recorded and a state in which all the ejection ports were unable to eject was confirmed.

[0215] The ink in the flow passages of the supply system and the liquid application device having the configuration shown in Fig. 5 was discharged. Next, 10 kg of maintenance liquid was filled into the main tank 1504. The maintenance liquid passed through the sub tank 1503, passed through the flow passages inside the ejection element substrate 1203 in the liquid application device 1200, and then the mixture of the residual ink and the maintenance liquid was discharged just before moving again to the sub tank 1503. In order to further discharge the mixture of the residual ink and the maintenance liquid inside the ejection element substrate 1203, capping was performed with the capping unit 1701 in Fig. 6, and the operation of suctioning with a negative pressure of -90 kPa for 10 seconds was repeated three times.

[0216] The maintenance liquid was again filled into the supply system and the flow paths of the liquid application device. Furthermore, the capping unit 1701 in Fig. 6 was filled with the maintenance liquid, and the ejection orifices were capped in a state where the maintenance liquid was in contact with the ejection orifices. In this state, the device was left for three days in an environment with a temperature of 25°C and a relative humidity of 55%.

[0217] Thereafter, the maintenance liquid was removed from the supply system having the configuration shown in FIG. 5 and the capping unit 1701 in FIG. 6. Next, the supply system and the liquid application device were filled with ink again, and the capping unit 1701 in FIG. 6 was used to cap the nozzles, and the operation of suctioning the nozzles for 10 seconds at a negative pressure of -90 kPa was repeated three times. Thereafter, an image showing the ejection state of all the ejection ports was recorded using an inkjet recording device having the configuration shown in FIG. 1, and the adhesion recovery property after the nozzles were left unattended was evaluated according to the evaluation criteria shown below. In Comparative Example 8, after it was confirmed that all the ejection ports were unable to eject, the maintenance liquid was not filled, and the capping unit 1701 in FIG. 6 was used to cap the nozzles, and the operation of suctioning the nozzles for 10 seconds at a negative pressure of -90 kPa was repeated three times. Thereafter, an image showing the ejection state of all the ejection ports was recorded, and the adhesion recovery property after the nozzles were left unattended was evaluated according to the evaluation criteria shown below. A: The number of non-discharging orifices was less than 10% of all orifices. B: The number of non-ejecting orifices was 10% or more and less than 20% of all the orifices. C: The number of non-ejecting orifices was 20% or more of the total number of orifices.

[0218] (wetted) The main tank 1504 of the supply system having the configuration shown in FIG. 5 was filled with the maintenance liquid. The maintenance liquid passed through the sub-tank 1503, passed through a flow path inside the discharge element substrate 1203 in the liquid deposition device 1200, and was then circulated back to the sub-tank 1503, thereby filling the inside of the circulation flow path with the maintenance liquid. Furthermore, the inside of the cap was filled with the maintenance liquid, and the discharge port was capped in a state where the maintenance liquid was in contact with the discharge port. In this state, the device was left in an environment of a temperature of 25° C. and a relative humidity of 55% for three days, and the maintenance liquid was removed from the supply system having the configuration shown in FIG. 5 and the cap. After repeating the above operation three and ten times, the peeling state of the joint between the support member 1232 and the first flow path member 1234 shown in FIG. 3 was photographed using an X-ray CT, and the liquid contact property was evaluated according to the evaluation criteria shown below. A: No peeling was observed even after 10 repetitions. B: No peeling was observed after 3 repetitions, but peeling was observed after 10 repetitions. C: Peeling was observed after three repetitions.

[0219] TIFF2025034262000009.tif188170

[0220] TIFF2025034262000010.tif77170

[0221] The disclosure of this embodiment includes the following configurations and methods. (Configuration 1) An aqueous maintenance liquid for use in a liquid application device that ejects aqueous ink containing a color material and resin particles, comprising: the resin particles include at least one selected from the group consisting of acrylic resin particles, styrene resin particles, urethane resin particles, and polyester resin particles; a portion of the liquid applying device that comes into contact with the water-based ink contains an epoxy resin composition obtained by polymerizing an epoxy resin and a curing agent that reacts with the epoxy resin; The aqueous maintenance liquid comprises a water-soluble compound represented by the following general formula (1): R 1 -XR 2 (1) In the general formula (1), X represents a sulfonyl group or a sulfoxide group, and R 1 and R 2 do not combine with each other to form a ring, and each independently represent an alkyl group which may be substituted with a hydroxyl group. (Configuration 2) R in the general formula (1) 1 and R 2 each independently represents a methyl group or an ethyl group. (Configuration 3) The aqueous maintenance liquid according to configuration 1 or 2, wherein X in general formula (1) is a sulfoxide group. (Configuration 4) The aqueous maintenance liquid according to any one of Configurations 1 to 3, wherein the content (mass %) of the water-soluble compound represented by general formula (1) in the aqueous maintenance liquid is 20 mass % or more and 80 mass % or less, based on the total mass of the aqueous maintenance liquid. (Configuration 5) The aqueous maintenance liquid according to any one of Configurations 1 to 4, wherein the glass transition temperature (°C) of the resin forming the resin particles is 80°C or lower. (Configuration 6) The aqueous maintenance liquid according to any one of Configurations 1 to 5, wherein the epoxy resin comprises a bisphenol A type epoxy resin. (Configuration 7) The aqueous maintenance liquid according to any one of Configurations 1 to 6, wherein the curing agent includes at least one selected from the group consisting of an amine-based curing agent and an acid anhydride-based curing agent. (Configuration 8) An ink set including an aqueous ink containing a coloring material and resin particles, and an aqueous maintenance liquid used in a liquid application device that ejects the aqueous ink, the resin particles include at least one selected from the group consisting of acrylic resin particles, styrene resin particles, urethane resin particles, and polyester resin particles; a portion of the liquid applying device that comes into contact with the water-based ink contains an epoxy resin composition obtained by polymerizing an epoxy resin and a curing agent that reacts with the epoxy resin; The ink set is characterized in that the aqueous maintenance liquid contains a water-soluble compound represented by the following general formula (1): R 1 -XR 2 (1) In the general formula (1), X represents a sulfonyl group or a sulfoxide group, and R 1 and R 2 do not combine with each other to form a ring, and each independently represent an alkyl group which may be substituted with a hydroxyl group. (Method 1) A maintenance method for a liquid-applying device, the method including a step of applying an aqueous maintenance liquid to a liquid-applying device that ejects an aqueous ink containing a coloring material and resin particles to record an image on a recording medium, the method comprising the steps of: the resin particles include at least one selected from the group consisting of acrylic resin particles, styrene resin particles, urethane resin particles, and polyester resin particles; a portion of the liquid applying device that comes into contact with the water-based ink contains an epoxy resin composition obtained by polymerizing an epoxy resin and a curing agent that reacts with the epoxy resin; The method for maintaining a liquid-applying apparatus, wherein the aqueous maintenance liquid contains a water-soluble compound represented by the following general formula (1): R 1 -XR 2 (1) In the general formula (1), X represents a sulfonyl group or a sulfoxide group, and R 1 and R 2 do not combine with each other to form a ring, and each independently represent an alkyl group which may be substituted with a hydroxyl group. (Method 2) An inkjet recording method including: a step of ejecting an aqueous ink containing a coloring material and resin particles from a liquid application device to record an image on a recording medium; and a step of applying an aqueous maintenance liquid to the liquid application device, the resin particles include at least one selected from the group consisting of acrylic resin particles, styrene resin particles, urethane resin particles, and polyester resin particles; a portion of the liquid applying device that comes into contact with the water-based ink contains an epoxy resin composition obtained by polymerizing an epoxy resin and a curing agent that reacts with the epoxy resin; The inkjet recording method according to the present invention, wherein the aqueous maintenance liquid contains a water-soluble compound represented by the following general formula (1): R 1 -XR 2 (1) In the general formula (1), X represents a sulfonyl group or a sulfoxide group, and R 1 and R 2 do not combine with each other to form a ring, and each independently represent an alkyl group which may be substituted with a hydroxyl group. (Configuration 9) An inkjet recording apparatus comprising: an aqueous ink containing a coloring material and resin particles; a liquid application device that ejects the aqueous ink to record an image on a recording medium; and an aqueous maintenance liquid that is applied to the liquid application device, the resin particles include at least one selected from the group consisting of acrylic resin particles, styrene resin particles, urethane resin particles, and polyester resin particles; a portion of the liquid applying device that comes into contact with the water-based ink contains an epoxy resin composition obtained by polymerizing an epoxy resin and a curing agent that reacts with the epoxy resin; The inkjet recording apparatus is characterized in that the aqueous maintenance liquid contains a water-soluble compound represented by the following general formula (1): R 1 -XR 2 (1) In the general formula (1), X represents a sulfonyl group or a sulfoxide group, and R 1 and R 2 do not combine with each other to form a ring, and each independently represent an alkyl group which may be substituted with a hydroxyl group.

Claims

1. 1. An aqueous maintenance liquid for use in a liquid application device that ejects an aqueous ink containing a color material and resin particles, the resin particles include at least one selected from the group consisting of acrylic resin particles, styrene resin particles, urethane resin particles, and polyester resin particles; a portion of the liquid applying device that comes into contact with the water-based ink contains an epoxy resin composition obtained by polymerizing an epoxy resin and a curing agent that reacts with the epoxy resin; The aqueous maintenance liquid contains a water-soluble compound represented by the following general formula (1): R １ -X-R ２ (1) In the general formula (1), X represents a sulfonyl group or a sulfoxide group, R １ and R ２ do not combine to form a ring, and each independently represents an alkyl group which may be substituted with a hydroxyl group.

2. R in the general formula (1) １ and R ２ The aqueous maintenance liquid according to claim 1 , wherein each of the groups independently represents a methyl group or an ethyl group.

3. 2. The aqueous maintenance liquid according to claim 1, wherein X in said general formula (1) is a sulfoxide group.

4. 2. The aqueous maintenance liquid according to claim 1, wherein the content (mass %) of the water-soluble compound represented by general formula (1) in the aqueous maintenance liquid is 20 mass % or more and 80 mass % or less, based on the total mass of the aqueous maintenance liquid.

5. 2. The aqueous maintenance liquid according to claim 1, wherein the resin forming the resin particles has a glass transition temperature (°C) of 80°C or lower.

6. 2. The aqueous maintenance liquid according to claim 1, wherein the epoxy resin comprises a bisphenol A type epoxy resin.

7. 2. The aqueous maintenance liquid according to claim 1, wherein the curing agent comprises at least one selected from the group consisting of an amine-based curing agent and an acid anhydride-based curing agent.

8. An ink set comprising an aqueous ink containing a coloring material and resin particles, and an aqueous maintenance liquid used in a liquid application device that ejects the aqueous ink, the resin particles include at least one selected from the group consisting of acrylic resin particles, styrene resin particles, urethane resin particles, and polyester resin particles; a portion of the liquid applying device that comes into contact with the water-based ink contains an epoxy resin composition obtained by polymerizing an epoxy resin and a curing agent that reacts with the epoxy resin; The ink set is characterized in that the aqueous maintenance liquid contains a water-soluble compound represented by the following general formula (1): R １ -X-R ２ (1) In the general formula (1), X represents a sulfonyl group or a sulfoxide group, R １ and R ２ do not combine to form a ring, and each independently represents an alkyl group which may be substituted with a hydroxyl group.

9. A maintenance method for a liquid application device, the method including a step of applying an aqueous maintenance liquid to a liquid application device that ejects an aqueous ink containing a color material and resin particles to record an image on a recording medium, the method comprising the steps of: the resin particles include at least one selected from the group consisting of acrylic resin particles, styrene resin particles, urethane resin particles, and polyester resin particles; a portion of the liquid applying device that comes into contact with the water-based ink contains an epoxy resin composition obtained by polymerizing an epoxy resin and a curing agent that reacts with the epoxy resin; The method for maintaining a liquid application device, wherein the aqueous maintenance liquid contains a water-soluble compound represented by the following general formula (1): R １ -X-R ２ (1) In the general formula (1), X represents a sulfonyl group or a sulfoxide group, R １ and R ２ do not combine to form a ring, and each independently represents an alkyl group which may be substituted with a hydroxyl group.

10. An inkjet recording method comprising: a step of ejecting an aqueous ink containing a coloring material and resin particles from a liquid application device to record an image on a recording medium; and a step of applying an aqueous maintenance liquid to the liquid application device, the resin particles include at least one selected from the group consisting of acrylic resin particles, styrene resin particles, urethane resin particles, and polyester resin particles; a portion of the liquid applying device that comes into contact with the water-based ink contains an epoxy resin composition obtained by polymerizing an epoxy resin and a curing agent that reacts with the epoxy resin; The inkjet recording method is characterized in that the aqueous maintenance liquid contains a water-soluble compound represented by the following general formula (1): R １ -X-R ２ (1) In the general formula (1), X represents a sulfonyl group or a sulfoxide group, R １ and R ２ do not combine to form a ring, and each independently represents an alkyl group which may be substituted with a hydroxyl group.

11. An inkjet recording apparatus comprising: an aqueous ink containing a coloring material and resin particles; a liquid application device that ejects the aqueous ink to record an image on a recording medium; and an aqueous maintenance liquid that is applied to the liquid application device, the resin particles include at least one selected from the group consisting of acrylic resin particles, styrene resin particles, urethane resin particles, and polyester resin particles; a portion of the liquid applying device that comes into contact with the water-based ink contains an epoxy resin composition obtained by polymerizing an epoxy resin and a curing agent that reacts with the epoxy resin; The inkjet recording apparatus is characterized in that the aqueous maintenance liquid contains a water-soluble compound represented by the following general formula (1): R １ -X-R ２ (1) In the general formula (1), X represents a sulfonyl group or a sulfoxide group, R １ and R ２ do not combine to form a ring, and each independently represents an alkyl group which may be substituted with a hydroxyl group.

Images