JP7275494B2 - TRANSFER, INKJET IMAGE FORMING APPARATUS, AND INKJET IMAGE FORMING METHOD - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer member having a material whose wettability (contact angle) of ink changes with an external stimulus and capable of obtaining a high-quality image, and an inkjet image forming apparatus and an inkjet image forming method equipped with the transfer member. .

2. Description of the Related Art An image forming method using an inkjet method is generally a method of ejecting ink droplets according to image information from an inkjet head for ejecting liquid to form ink dots on a recording medium to obtain a recorded image. The inkjet ink (hereinafter also simply referred to as "ink") used here is required to have stable ejection performance from the inkjet head and high-quality image forming ability on the recording medium.

In image formation by an inkjet recording method, image formation aptitude on various recording media including plain paper is required in addition to dedicated inkjet paper. As one of the inkjet image recording methods that meet such demands, a transfer-type inkjet image forming method is known.

For example, Japanese Patent Application Laid-Open No. 5-255623 discloses that an intermediate image is formed on an intermediate transfer member by an inkjet recording method, and the intermediate image is transferred to a recording medium to obtain a desired image on the recording medium. An ink jet recording method is disclosed. However, in the patent document, the initial contact angle between the intermediate transfer member made of silicon film and the ink is set to be in the range of 30 to 70 degrees, and if the contact angle is less than 30 degrees, irregular dots are formed. However, there are problems such as the ink dot diameter becoming large and being unsuitable for practical use.

Furthermore, in the transfer type ink jet image forming method, bleeding or image distortion may occur during the intermediate image formation stage depending on the combination of the physical properties of the applied ink and the material of the surface of the transfer member.

In order to solve the above problems, pretreatment means for applying a pretreatment liquid containing a component that reacts with at least one component in the recording liquid to the transfer body, and image forming means for forming an image by applying the recording liquid to the transfer body. , and a transfer means for transferring an image from the transfer member to a recording medium. (see, for example, Patent Document 1). Patent Literature 1 states that the properties required for the transfer member are preferably moderate wettability with the ink liquid and moderate releasability of the ink liquid from the transfer body. If the wettability is poor, image deterioration may occur on the transfer member, and if the releasability is insufficient, the image may be missing. Silicone-based resins and various other resins can be used as the material constituting such an intermediate transfer body, and the surface characteristics can be controlled by chemically or physically treating the surface of these resins. there is However, in the printing on the transfer body using the ink liquid in Patent Document 1, the properties required for the transfer body are the "wettability" of the ink liquid to the transfer body and the "releasability" of the formed transfer image. Desired. However, in many cases, wettability required for fine image formation is not compatible with releasability required for transferring a transferred image to a recording medium. That is, if the wettability of the ink liquid to the transfer member is improved, fine image formation becomes possible due to the wetting and spreading of the ink droplets. Conversely, if the releasability is improved, the wettability of the ink liquid to the transfer body is lowered, which may make image formation difficult. In order to achieve moderate wettability to the transfer body and moderate releasability, it is a balanced design that allows a decrease in either aptitude, so it is difficult to achieve both characteristics at a high level. .

Further, in Patent Document 2, electrowetting is used as a transfer type image forming method that ensures both the wettability of a reaction liquid and ink to an intermediate transfer member and the releasability of transferring an intermediate image to a recording medium. An image forming method is disclosed that includes a step of controlling the wettability of a transfer body to a reaction liquid and ink. However, in Patent Document 2, it is not sufficient in terms of achieving both moderate wettability to the transfer body and moderate releasability. have the problem of

That is, in the transfer type inkjet image forming method, in the process of transferring from the transfer body to the recording medium, which is a printing device, while ensuring the wetting and spreading of the ink when it lands on the transfer body, color mixing is prevented. There is a contradiction in securing the releasability from the transfer body while ensuring the wetting and spreading on the transfer body, and it is difficult to achieve both of these characteristics.

JP-A-2002-321350 JP 2015-189109 A

The present invention has been made in view of the above problems and circumstances, and the problem to be solved is a transfer body that achieves both wettability of the ink to the transfer body and releasability of the ink-jet image formed from the transfer body. Another object of the present invention is to provide an inkjet image forming apparatus and an inkjet image forming method equipped with the transfer member.

In order to solve the above problems, as a result of extensive research, the present inventors have found a transfer member for an inkjet image forming apparatus using inkjet ink, and a material whose contact angle changes due to an external stimulus on the surface of the transfer member. It has been found that it is possible to provide a transfer body that achieves both wettability of ink to the transfer body and releasability of an inkjet image formed from the transfer body by a transfer body characterized by carrying , led to the present invention.

That is, the above problems of the present invention are solved by the following means.

1. A transfer member for an inkjet image forming apparatus using inkjet ink,
A material whose contact angle changes with an external stimulus is carried on the transfer substrate,
the external stimulus is a thermal stimulus;
The material whose contact angle changes due to an external stimulus is a thermosensitive polymer and has a lower critical solution temperature (LCST), and the LCST is in the range of 22 to 47 ° C.,
When using an inkjet ink having a contact angle with respect to the material supported on the transfer substrate at 25° C. (room temperature) in the range of 38 to 82 degrees, the ink is supported on the transfer substrate at 50° C. the contact angle to the material being carried on the transfer substrate is higher than the contact angle to the material being carried on the transfer substrate at 25° C. within the range of 3 to 27 degrees
A transfer body characterized by:

2 . 2. The transfer member according to claim 1, which is applied to an image forming method using a water-based dye ink or an organic solvent-based dye ink as the inkjet ink.

3 . 2. The transfer member according to claim 1, which is applied to an image forming method using an actinic radiation-curable inkjet ink that is cured by actinic radiation as the inkjet ink.

4 . The actinic radiation curable inkjet ink contains a gelling agent, the gelling temperature is equal to or higher than the LCST of the heat-sensitive responsive polymer contained in the transfer member, and the gelling state is obtained at the gelling temperature or lower. 4. A transfer member according to claim 3 , characterized in that:

5 . An inkjet image forming apparatus comprising the transfer member according to any one of items 1 to 4 .

6 . An inkjet image forming method using a transfer body carrying a material whose contact angle changes with an external stimulus on a transfer base material,
Using an actinic radiation curable inkjet ink as the inkjet ink,
cooling the transfer body to change the degree of contact angle of the actinic radiation curable inkjet ink with respect to ink droplets;
A step of landing ink droplets of the actinic radiation curable inkjet ink on the transfer body;
heating the transfer body to change the degree of contact angle of the ink droplets on the surface of the transfer body;
transferring the ink droplets onto a recording medium;
a step of irradiating the ink droplets transferred onto the recording medium with an actinic ray to form a cured film constituting an inkjet image;
a cleaning step of removing the inkjet image remaining on the transfer body;
An inkjet image forming method, comprising:

7 . An inkjet image forming method using the transfer member according to item 1 or 2 ,
As the inkjet ink, using a water-based dye ink or an organic solvent-based dye ink,
cooling the transfer body to change the degree of contact angle of the inkjet ink with respect to ink droplets;
A step of landing ink droplets of the inkjet ink on the transfer body;
heating the transfer body to change the degree of contact angle of the ink droplets on the surface of the transfer body;
transferring the ink droplets onto a recording medium;
a step of applying heat to the ink droplets transferred onto the recording medium to form a cured film constituting an inkjet image;
a cleaning step of removing the inkjet image remaining on the transfer body;
An inkjet image forming method, comprising:

According to the present invention, a transfer body that achieves both wettability of ink to the transfer body and releasability of an inkjet image formed from the transfer body, an inkjet image forming apparatus having the transfer body, and an inkjet image forming apparatus. can provide a method.

Although the effect expression mechanism or action mechanism of the transcription body having the structure defined in the present invention is not clear, it is speculated as follows.

As described above, in the conventional transfer-type inkjet image forming method, while ensuring wetting and spreading when ejected ink droplets land on the transfer base material, color mixing is prevented, and the ink components are transferred from the transfer base material to the recording medium. However, there is a contradiction between the two characteristics of ensuring wetting and spreading and ensuring releasability from the transfer body, and it is difficult to achieve both.

In view of the above problems, the present inventors conducted intensive studies, and found that, on the surface of the transfer base material of the transfer body, a material having a property of changing the contact angle due to external stimulation, for example, the contact angle changing due to thermal stimulation. A heat-sensitive responsive polymer is provided on the surface of the transfer base material, and the contact angle on the transfer body surface is controlled by controlling the temperature of the transfer base material at the time of impact and transfer, so that the ink liquid on the transfer body surface It has been found that both droplet wetting and spreading properties and releasability (transferability) can be achieved. Furthermore, by including a gelling agent in the inkjet ink, the gelling effect when the ink droplets land on the transfer body prevents color mixing, and the temperature range does not cause remelting of the gelling agent. Since the contact angle can be controlled, this is a preferred embodiment in that color mixing due to remelting can be prevented.

Further details are given below.

In the formation of an inkjet recorded image, when a hydrophilic ink is applied as the ink, if the transfer base material is hydrophilic, the ink droplets landed on the base material are likely to wet and spread. , the transferability to the recording medium is lowered. Conversely, when the transfer base material is hydrophobic, the ink droplets that land on the transfer base material are less likely to wet and spread, and color mixing is likely to occur, but on the other hand, the affinity with the transfer base material is low. Therefore, the transferability to the recording medium at the time of transfer is enhanced.

In terms of the surface characteristics of the transfer body having such various characteristics, in order to improve the transferability while ensuring the wetting and spreading as the transfer body, basically, the ink droplets landing on the transfer body In some cases, the degree of hydrophilicity is high, that is, the contact angle of the ink droplets that land is small, and the degree of hydrophobicity is high during transfer to the recording medium, that is, the contact angle of the ink droplets that land is large. It is considered preferable to have

As a material to be applied to the transfer substrate, the present inventor uses a material whose contact angle changes due to external stimuli such as environmental temperature, light of various wavelengths, magnetic fields, sound waves, etc., to ensure wet spreadability and transfer. As a result of intensive studies on techniques that can improve the efficiency, it was found that the above object can be achieved by carrying, on the transfer body, a material whose contact angle is changed by an external stimulus. For example, the inventors have found that it is effective to apply a material whose contact angle is changed by a thermal stimulus as an external stimulus, more specifically, a thermosensitive polymer whose contact angle is changed by an external stimulus.

In a more preferred embodiment, a film containing poly-N-isopropylacrylamide, which exhibits a small contact angle in a low-temperature environment and a large contact angle in a high-temperature environment, is used as a material that changes the contact angle of an ink droplet that lands on the transfer body. By forming it on the transfer base material, the ink ejected onto the transfer body, for example, the ink containing a gelling agent, spreads after it lands and then gels, preventing color mixing with ink droplets of other colors. can do. By heating the transfer body above the LCST (hydrophilicity/hydrophobicity transition point) of the thermosensitive polymer and below the melting temperature of the gel ink during transfer, the surface of the transfer body switches to the hydrophobic side, and the ink is transferred to the transfer body. It is presumed that the characteristics of being able to be transferred without causing color mixing due to re-melting can be realized because it becomes easy to release from the mold and does not reach the melting temperature of the gel ink.

FIG. 1 is a flow chart showing an example of steps of an inkjet image forming method using the transfer member of the present invention; Schematic configuration diagram showing an example of an inkjet image forming apparatus equipped with the transfer member of the present invention.

A transfer member of the present invention is a transfer member for an inkjet image forming apparatus using inkjet ink, wherein a transfer substrate carries a material whose contact angle is changed by an external stimulus, and the external stimulus is a thermal stimulus. and the material whose contact angle changes with an external stimulus is a thermosensitive polymer, has a lower critical solution temperature (LCST), and the LCST is in the range of 22 to 47°C, and 25°C . When using an inkjet ink having a contact angle with respect to the material supported on the transfer substrate at room temperature (room temperature) in the range of 38 to 82 degrees , the ink is supported on the transfer substrate at 50°C. The contact angle to the material is higher than the contact angle to the material carried on the transfer substrate at 25° C. within a range of 3 to 27 degrees. This feature is a technical feature common to the inventions according to the following embodiments .

As an embodiment of the present invention, the external stimulus is a thermal stimulus, and the material whose contact angle is changed by the thermal stimulus is a thermoresponsive polymer, from the viewpoint that the effects of the present invention can be exhibited more effectively. and a material having a lower critical solution temperature (LCST) is preferable from the viewpoint of easy mechanical control and utilization in areas such as high-speed printing.

Further, the contact angle A of the inkjet ink on the transfer body when the transfer body temperature is less than the LCST of the thermoresponsive polymer is the above-mentioned when the transfer body temperature is equal to or higher than the LCST of the thermoresponsive polymer By making the contact angle B smaller than the contact angle B of the inkjet ink on the transfer member, it is preferable in that it is possible to further achieve both ink wettability and releasability.

More specifically, the value of (contact angle B - contact angle A) is preferably 1 degree or more, more preferably in the range of 1 to 30 degrees, and still more preferably in the range of 2 to 20 degrees. and particularly preferably within the range of 3 to 15 degrees.

The inkjet ink is preferably applied to an image forming method using a water-based dye ink or an organic solvent-based dye ink.
In addition, by applying an actinic radiation-curable inkjet ink that is cured by actinic rays as the inkjet ink, excessive wetting and spreading of the ink droplets can be prevented, and the internal cohesive force can be strengthened during transfer, increasing the transfer efficiency. It is preferable in that it can

Further, in the present invention, the actinic radiation curable inkjet ink contains a gelling agent, the gelling temperature is equal to or higher than the LCST of the heat-sensitive responsive polymer contained in the transfer body, and gels at the gelling temperature or lower. It is a preferred mode to take a state. Ink that does not contain a gelling agent causes some movement of the ink when transferred to a recording medium, which may affect the image quality. On the other hand, in image formation using an ink containing a gelling agent, when the ink droplets land on the transfer body, the ink droplets are wetted and spread while being gelled. Since the gelation point is higher than the LCST, if the relationship LCST<temperature<gelling point is satisfied, the gelling agent does not melt again, which is preferable in that transfer can be performed without deterioration of image quality.

When a heat-sensitive responsive polymer is applied to the transfer body, the lower the LCST, the faster the response and the higher the transfer rate. However, if the LCST is too low, for example, if the LCST is lower than normal temperature, the contact angle may shift to the high side regardless of the presence or absence of heating, which may affect wet spreading and image quality.

Further, in the inkjet image forming method of the present invention using a transfer body carrying a material whose contact angle changes with an external stimulus on a transfer base material, an actinic radiation curable inkjet ink is used as the inkjet ink, and the transfer body is cooled to change the degree of contact angle with respect to the ink droplets of the actinic radiation-curable inkjet ink; the step of landing the ink droplets of the actinic radiation-curable inkjet ink on the transfer body; and the transfer body to change the degree of contact angle of the ink droplets on the transfer body surface; transferring the ink droplets onto a recording medium; and activating the ink droplets transferred onto the recording medium. An inkjet image forming method comprising a step of irradiating a light beam to form a cured film constituting an inkjet image, and a cleaning step of removing the inkjet image remaining on the transfer member. It is possible to achieve both wettability of the ink and releasability of the ink-formed image from the transfer body, and to obtain a higher-quality inkjet transferred image without image quality deterioration.
Moreover, water-based dye ink or organic solvent-based dye ink can be used as the inkjet ink.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention, its constituent elements, and modes and modes for carrying out the present invention will be described below. In the present application, "-" is used to mean that the numerical values before and after it are included as the lower limit and the upper limit. Also, in the following description using the drawings, the numerals in parentheses after each component represent the reference numerals of each component described in each drawing.

《Transcript》
The transfer member of the present invention is a transfer member for an inkjet image forming apparatus using inkjet ink, wherein the transfer base material carries a material whose contact angle is changed by an external stimulus , and the external stimulus is applied to the transfer substrate. , is a thermal stimulus, and the material whose contact angle changes due to the external stimulus is a thermosensitive polymer and has a lower critical solution temperature (LCST), and the LCST is in the range of 22 to 47 ° C. , When using an inkjet ink having a contact angle with respect to the material carried on the transfer substrate at 25° C. (room temperature) in the range of 38 to 82 degrees, the transfer substrate at 50° C. The contact angle with respect to the material carried on the transfer substrate is higher than the contact angle with respect to the material carried on the transfer substrate at 25° C. within the range of 3 to 27 degrees .

The details of the constituent elements of the transfer body of the present invention are described below.

[Transfer base material]
Materials constituting the transfer substrate according to the present invention include, for example, polyester (e.g., polyethylene terephthalate (abbreviation: PET), polyethylene naphthalate (abbreviation: PEN), etc.), polycarbonate, polyurethane, fluororesin, nylon, polymethyl Methacrylates, acrylics and polyarylates, cycloolefin resins, polyphenylene sulfides, polyarylates, polysulfones, polyethersulfones, polyetherimides, polyimides, polyamideimides, polyetheretherketones and the like can be mentioned. Among them, polyimide is preferable from the viewpoint of heat resistance.

In addition, the transfer base material can be subjected to surface treatment as necessary, and examples thereof include ultraviolet treatment, excimer treatment, flame treatment, ozone treatment, corona treatment, plasma treatment, silyl treatment, and fluorination treatment. be done.

The shape of the transfer base material is not particularly limited as long as it has a shape that can be in contact with the recording medium, such as a roller shape, an endless belt shape, and a sheet shape.

[External stimulus response layer]
(Materials whose contact angle changes with external stimulation)
In the transfer member of the present invention, a layer carrying a material whose contact angle changes with an external stimulus (hereinafter also referred to as an external stimulus responsive layer) is provided on the transfer substrate constituting the transfer member. The external stimulus responsive layer may be formed as a thin coating film on the surface of the transfer base material, or may be formed as a constituent layer having a specific layer thickness.

The "external stimulus" as used in the present invention includes heat stimulus.

Materials that respond to stimulation by applying heat include a crosslinked polymer having a lower critical solution temperature (LCST) and an IPN (interpenetrating network structure) of a two-component polymer gel that hydrogen bonds with each other. mentioned.

[Thermal response layer]
As a representative example of the external stimulus responsive layer, a thermosensitive responsive layer suitable for the present invention that responds to a thermal stimulus will be described below.

<Heat-Sensitive Polymer Having Lower Critical Solution Temperature (LCST)>
Among the materials listed above whose contact angle changes with an external stimulus, it is preferable to apply a heat-sensitive responsive polymer having a lower critical solution temperature (LCST) in the present invention.

Hereinafter, in the present invention, a thermoresponsive polymer suitable as a material whose contact angle is changed by an external stimulus will be described in detail.

In the present invention, a thermoresponsive polymer is a polymer material that has the function of reversibly changing the contact angle with respect to an ink droplet depending on temperature. In a thermosensitive polymer, for example, the temperature at which the contact angle changes is called the critical temperature, and the threshold temperature at which a high contact angle is indicated on the high temperature side and a low contact angle on the low temperature side is called the lower critical temperature (LCST). .

In the present invention, the heat-sensitive responsive polymer includes, for example, D.I. Roy, W.; L. A. Brooks andB. S. Sumerlin, Chem. Soc. Rev. , 2013, 42, 7214-7243. 3, 4, 5, 7, 8, 9, 10, 11, 12, 13, 13, 14, 14, 15, 16, 18, 18, 18, 19, 20, 20, 20, 20, 20, 20, 20, etc. can be exemplified.

Examples of organic monomers forming such thermosensitive polymers include N-substituted acrylamide derivatives, N,N-disubstituted acrylamide derivatives, N-substituted methacrylamide derivatives, N,N-disubstituted methacrylamide derivatives, and the like. can be preferably used, specifically N-isopropylacrylamide, N-isopropylmethacrylamide, Nn-propylacrylamide, Nn-propylmethacrylamide, N-cyclopropylacrylamide, N-cyclopropylmethacrylamide , N-ethoxyethylacrylamide, N-ethoxyethylmethacrylamide, N-tetrahydrofurfurylacrylamide, N-tetrahydrofurfurylmethacrylamide, N-ethylacrylamide, N-ethyl-N-methylacrylamide, N,N-diethylacrylamide, N-methyl-Nn-propylacrylamide, N-methyl-N-isopropylacrylamide, N-acryloylpiperidine, N-acryloylpyrrolidine.

Examples of thermoresponsive polymers prepared from the above organic monomers include poly(N-isopropylacrylamide), poly(Nn-propylacrylamide), poly(N-cyclopropylmethacrylamide), poly(N-isopropyl methacrylamide), poly(Nn-propylmethacrylamide), poly(N-ethoxyethylacrylamide), poly(N-ethoxyethylmethacrylamide), poly(N-tetrahydrofurfurylacrylamide), poly(N-tetrafluoro furyl methacrylamide), poly(N-ethylacrylamide), poly(N,N-diethylacrylamide), poly(N-acryloylpiperidine), poly(N-acryloylpyrrolidine).

As the polymer of the organic monomer, it is also effective to use a copolymer obtained by polymerizing a plurality of different organic monomers selected from these as well as a polymer from a single organic monomer as described above. .

The heat-sensitive responsive polymer according to the present invention is preferably a polymer composed of the above organic monomers, but copolymers of the above organic monomers with other water-soluble organic monomers or organic solvent-soluble organic monomers can also be obtained. Any polymer that exhibits both hydrophilicity and hydrophobicity can be used. Specific examples of organic monomers used for copolymerization include acrylamides such as N-alkylacrylamide, N,N-dialkylacrylamide and acrylamide, or N-alkylmethacrylamide, N,N-dialkylmethacrylamide, methacrylamide and methacrylamides such as amides. More preferably, N-alkylacrylamide or N,N-dialkylacrylamide is used. As the alkyl group, those having 1 to 4 carbon atoms are preferably selected. In addition, acryloylmorpholine, N,N-dimethylaminopropylacrylamide, N-acryloylmethylhomopiperadine, N-acryloylmethylpiperadine and the like can also be used.

At least one of the thermoresponsive polymers may contain an acrylic monomer and its polymer (acrylic resin), and the lower critical temperature of the thermoresponsive polymer can be changed by the copolymerization ratio with the acrylic resin.

The acrylic monomer in the present invention may be a general acrylic resin such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, or a derivative thereof. Acrylic resins, which are polycyclic hydrocarbon compounds having an alicyclic hydrocarbon skeleton, may also be used. The polycyclic hydrocarbon compounds have an aliphatic polycyclic structure and a three-dimensional crosslinked structure. Examples thereof include tricyclodecanedimethanol dimethacrylate, tricyclodecanedimethanol diacrylate, adamantyl methacrylate, adamantyl acrylate, isobornyl methacrylate, isobornyl acrylate, vinylnorbornene, and the like.

In addition, for example, (polyoxyalkylene) acrylate and methacrylate are commercially available hydroxypoly(oxyalkylene) materials, such as trade name "Pluronic" [Pluronic (manufactured by Asahi Denka Kogyo Co., Ltd.)], Adeka Polyether (Asahi Denka Kogyo Co., Ltd.). Co.), Carbowax [Carbowax (Glico Products)], Triton [Toriton (Rohm and Haas)] and P.I. E. G (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) can be produced by reacting it with acrylic acid, methacrylic acid, acryl chloride, methacrylic chloride, acrylic anhydride, or the like by a known method.

In addition, as a commercially available polyalkylene glycol mono (meth) acrylate manufactured by NOF Co., Ltd., Blenmer PE-90, Blenmer PE-200, Blenmer PE-350, Blenmer AE-90, Blenmer AE-200, Blenmer AE-400, Blenmer PP-1000, Blenmer PP-500, Blenmer PP-800, Blenmer AP-150, Blenmer AP-400, Blenmer AP-550, Blenmer AP-800, Blenmer 50PEP-300, Blenmer 70PEP-350B, Blenmer AEP series, Blemmer 55PET-400, Blemmer 30PET-800, Blemmer 55PET-800, Blemmer AET series, Blemmer 30PPT-800, Blemmer 50PPT-800, Blemmer 70PPT-800, Blemmer APT series, Blemmer 10PPB-500B, Blemmer 10APB-500B etc.

The form of copolymerization may be random copolymerization or block copolymerization. Random copolymerization is preferred in order to sharpen the change in hydrophilicity and hydrophobicity at the lower critical temperature.

In these thermosensitive polymers, the polymerization initiator is preferably an initiator that generates radicals because it is polymerization of an acrylic monomer and an amide monomer. A system initiator can be used.

Oil-soluble peroxide-based or azo-based initiators are preferred, and examples include benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, orthochlorobenzoyl peroxide, orthomethoxybenzoyl peroxide, methyl ethyl ketone peroxide, and diisopropyl peroxide. peroxide initiators such as peroxydicarbonate, cumene hydroperoxide, cyclohexanone peroxide, t-butyl hydroperoxide, diisopropylbenzene hydroperoxide, 2,2'-azobisisobutyronitrile, 2,2 '-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,3-dimethylbutyronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2' -azobis(2,3,3-trimethylbutyronitrile), 2,2'-azobis(2-isopropylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'- Azobis(4-methoxy-2,4-dimethylvaleronitrile), 2-(carbamoylazo)isobutyronitrile, 4,4′-azobis(4-cyanovaleric acid), dimethyl-2,2′-azobisisobutyryl rate, etc.

In particular, organic peroxides such as tertiary isobutyl hydroperoxide, cumene hydroperoxide and paramenthane hydroperoxide, and hydrogen peroxide are preferred.

In addition, photopolymerization initiators are similarly preferred as polymerization initiators. For example, acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4 -chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, Michler's ketone, benzoin propyl ether, benzoin ethyl ether, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methyl Examples include photoradical initiators such as propan-1-one and 2-hydroxy-2-methyl-1-phenylpropan-1-one.

These polymerization initiators are preferably used within a range of 0.01 to 20% by mass, particularly within a range of 0.1 to 10% by mass, based on the above monomers.

In the present invention, an organic solvent or water may or may not be used at the site of the reaction during the production process of the polymer. Preferably, no solvent is used, as the solvent must be removed in a later step. Organic solvents include alcohols such as methanol, ethanol and isopropyl alcohol, esters such as ethyl acetate and methyl acetate, ketones such as methyl ethyl ketone and acetone, ethers such as ether and isopropyl ether, and cyclic ethers such as tetrahydrofuran and dioxane. toluene, which is an aromatic hydrocarbon, etc., is not particularly limited.

(Method for forming thermosensitive layer)
As a method for coating the surface of the transfer base material with the thermosensitive polymer according to the present invention, there is a method in which the transfer base material is coated with a monomer and then polymerized, and a method in which the monomer is polymerized in advance to form a thermosensitive polymer. There is a coating method, or a method of immersing the transfer base material in a solution containing a monomer and then polymerizing it, and any of these methods may be used.

There are no particular restrictions on the method of applying the heat-sensitive responsive polymer or its monomer onto the transfer base material. well-known methods such as a method, a gravure coating method, an extrusion coating method, a vacuum deposition method (sputtering method), and the like can be used.

As a technique for immobilizing the thermosensitive polymer on the transfer base material, either curing by heat or curing by UV irradiation may be adopted.

Curing by UV irradiation is preferable from the viewpoint of rapid reaction, and when UV light is used, the light source may be, for example, a low pressure, medium pressure, or high pressure mercury lamp, a metal halide lamp, or an ultraviolet region having an operating pressure of 0.1 kPa to 1 MPa. Conventionally known lamps such as xenon lamps, cold cathode tubes, hot cathode tubes, and LEDs having an emission wavelength of .

In the present invention, the amount of the heat-sensitive responsive polymer to be applied to the transfer substrate is not particularly limited, but it is preferably in the range of 0.1 to 5.0 μg/cm ² , and 0.5 μg/cm 2 . It is more preferably in the range of ~3.0 μg/cm ² .

An example of the method for forming the thermoresponsive layer is shown below, but the present invention is not limited to the method exemplified here.

For example, a polyimide film is used as the transfer base material, and the surface of the transfer base material is subjected to a corona discharge treatment to make the surface hydrophilic, then aminopropyltriethoxysilane is sprayed, then an aqueous ammonia solution is sprayed, and then the temperature is maintained at 80°C. Dry with

The polyimide film is then immersed in a dichloromethane solution of 2-bromoisobutyryl bromide and triethylamine at 25° C. for 12 hours. Thereafter, the polyimide film is washed with dichloromethane and dried. The resulting polyimide film was treated with a methanol/water solution containing N-isopropylacrylamide (NIPAAm), N,N,N',N″,N″-pentamethyldiethylenetriamine, and copper(I) chloride/copper(II) bromide. and allowed to stand at room temperature for a predetermined time. By spray-washing the obtained polyimide film with methanol and drying it at 55° C., a transfer body having poly(N-isopropylacrylamide) as a thermosensitive polymer can be produced.

<<Inkjet image forming method>>
An inkjet image forming method using the transfer member of the present invention will be described below.

First, a basic process flow relating to the ink jet image forming method using the transfer member of the present invention will be described.

As an inkjet image forming method,
1) As the ink, for example, actinic radiation curable inkjet ink is used,
2) cooling the transfer body to change the degree of the contact angle of the ink droplets of the actinic radiation-curable inkjet ink, specifically, to reduce the contact angle;
3) A step of landing the ink droplets on a transfer body;
4) A step of applying a thermal stimulus as an external stimulus to the transfer body to heat the transfer body to change the degree of contact angle of the ink droplets on the surface of the transfer body, specifically, the surface characteristics of the transfer body. from a small contact angle characteristic to a large contact angle characteristic to increase the contact angle of the ink droplet on the surface;
5) transferring the ink image onto a recording medium;
6) A step of irradiating the ink droplets transferred onto the recording medium with, for example, an actinic ray to form a cured film of the image;
7) a cleaning step of removing the inkjet image remaining on the transfer body;
It can be configured by

Next, the details of the inkjet image forming method will be described with reference to the drawings.

FIG. 1 is a flow diagram showing an example of the image forming process of an ink jet image forming method using the transfer member of the present invention, in which a heat-sensitive responsive polymer is used as a material whose contact angle changes with an external stimulus.

A transfer body (1) shown in step a of FIG. 1 has a heat-sensitive layer (3) containing a heat-sensitive polymer formed on a transfer substrate (2). In step a of FIG. 1, the transfer body is cooled to be below the lower critical solution temperature (LCST) of the thermosensitive polymer, thereby changing the surface properties of the thermosensitive layer (3A) to the ink droplets (4). Change the degree of the contact angle to the small contact angle side.

Next, in step b, ink droplets (4) are made to land on the thermal response layer (3A) in this state.

Next, as shown in step c of FIG. 1, the ink droplets (4A) that land on the thermal response layer (3A) having a lower critical solution temperature (LCST) or less are deposited on the thermal response layer (3A) having a small contact angle characteristic. ), it becomes wet and spreads on the top.

Next, as shown in step d of FIG. 1, the transfer body (1) on which the ink droplets (4A) have landed is heated to the lower critical solution temperature (LCST) or higher of the thermosensitive polymer contained in the thermosensitive layer. As described above, by performing thermal stimulation (heating treatment), the surface characteristics of the thermoresponsive layer (3B) shift from a small state to a large state as the contact angle with respect to the ink droplet, and accordingly, the ink droplet lands. The contact angle of the ink droplet (4B) also increases.

Next, as shown in step e of FIG. 1, the ink droplets (4B) having a large contact angle are pressed against the recording medium (5), which is the object to be transferred, so that the ink droplets (4B) ) is transferred onto the recording medium (5).

Next, although not shown in FIG. 1, the inkjet image residue remaining on the transfer member is removed in a cleaning step.

Finally, by cooling the transfer body to below the lower critical solution temperature (LCST) again, the surface properties of the thermal response layer are changed from the thermal response layer (3B) having large contact angle characteristics to the small Return to step a in FIG.

By repeating this, it is possible to continuously form an inkjet image using the transfer member.

Next, details of a recording medium, an inkjet ink, and an inkjet recording apparatus applicable to the inkjet image forming method using the transfer member of the present invention will be described.

[recoding media]
The recording medium (5) used to transfer the ink droplets formed on the transfer member as described in step e of FIG. 1 will be described.

Examples of recording media applicable to the present invention include, in addition to ink jet paper having an ink absorbing layer, plain paper used for copying and the like, paper substrates such as art paper, and ordinary uncoated paper. , In addition to coated paper in which both sides of the base paper are coated with resin, etc., various laminated papers, synthetic papers, etc., various non-absorbent plastics and their films used for so-called flexible packaging can be used. include, for example, polyethylene terephthalate (PET), oriented polystyrene (OPS), oriented polypropylene (OPP), oriented nylon (ONy), polyvinyl chloride (PVC), polyethylene (PE), triacetyl cellulose (TAC) films can be done. Other plastics that can be used include polycarbonate (PP), acrylic resin, ABS resin, polyacetal, PVA, and rubbers. It is also applicable to metals and glasses.

Plain paper applicable to the present invention includes, for example, high-grade printing paper, medium-grade printing paper, low-grade printing paper, thin printing paper, lightly coated printing paper, special printing paper such as colored high-quality paper, form paper, PPC paper ( copy paper) and other information paper.

As art paper, for example, OK Kinto N, Satin Kinto N, SA Kinto, Ultra Satin Kinto N, OK Ultra Aqua Satin, OK Kinto Single Sided, N Art Post, NK Special Double Sided Art, Raicho Super Art N, Raicho Super Art MN, Raicho Art N, Raicho Daru Art N, and the like.

Examples of coated paper include POD Gloss Coat, OK Top Coat +, OK Top Coat S, Aurora Coat, Mu Coat, Mu White, Raicho Coat N, Utrillo Coat, Pearl Coat, White Pearl Coat, POD Matt Coat, New Age, New Age W, OK Top Coat Matte N, OK Royal Coat, OK Top Coat Dull, and the like.

[Ink composition]
The inks applicable to the inkjet image forming method of the present invention are not particularly limited, and include water-based inks containing water-soluble organic solvents (dye type, pigment type), solvent inks using organic solvents as a vehicle, curing by UV rays, and the like. Examples include actinic radiation curable ink containing a photopolymerizable compound that can be used, and solid ink (hot-melt ink) containing wax or the like.

As aqueous inks, for example, JP-A-2010-270322, JP-A-2011-006657, JP-A-2011-144303, JP-A-2012-031246, JP-A-2014-025067, JP-A-2015 -178624, JP-A-2016-053184, and the like.

Examples of solvent inks include ink compositions described in JP-A-2008-094976, JP-A-2011-089026, JP-A-2016-166311, and the like.

[Actinic radiation curable ink]
In the present invention, among the various inks described above, actinic ray-curable inks that are cured by actinic rays are preferable in that the intended effect of the present invention can be exhibited more effectively. More preferably, the actinic radiation curable ink contains a gelling agent, has a gelation temperature equal to or higher than the LCST temperature of the heat-sensitive responsive polymer contained in the transfer member, and takes a gel state at a gelation temperature or lower. is the preferred form.

The actinic radiation curable ink applicable to the present invention will be described below.

The actinic radiation curable ink according to the present invention is mainly composed of a colorant (for example, pigment, dye, etc.), a photopolymerizable compound, a photopolymerization initiator, a polymerization inhibitor, and the like.

Furthermore, as described above, it is a preferred embodiment that the actinic radiation-curable ink according to the present invention contains a gelling agent. Details of each component of the actinic radiation curable ink according to the present invention will be described below.

(Photopolymerizable compound)
The actinic radiation-curable ink suitable for the present invention preferably contains at least a photopolymerizable compound having a function of being cured by actinic radiation.

A photopolymerizable compound may be a monomer, a polymerizable oligomer, a prepolymer, or a mixture thereof. The ink according to the present invention may contain only one type of photopolymerizable compound, or may contain two or more types of the photopolymerizable compound.

The actinic rays referred to here are, for example, energy rays such as electron rays, ultraviolet rays, α rays, γ rays, and X rays, and preferably ultraviolet rays or electron rays. Examples of the photopolymerizable compound include radically polymerizable compounds and cationic polymerizable compounds, preferably radically polymerizable compounds.

The content of the photopolymerizable compound is, for example, preferably in the range of 1 to 97% by mass with respect to the total mass of the ink according to the present invention from the viewpoint of film physical properties such as curability and flexibility. It is more preferably within the range of 95% by mass.

<Radical polymerizable compound>
The radically polymerizable compound applicable to the present invention is preferably an unsaturated carboxylic acid ester, more preferably a (meth)acrylate.

In the present invention, "(meth)acrylate" means acrylate or methacrylate, "(meth)acryloyl group" means acryloyl group or methacryloyl group, and "(meth)acryl" means acrylic Or means methacrylic.

Examples of (meth)acrylates include isoamyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, isomylstil (meth)acrylate, isostearyl (meth)acrylate acrylates, 2-ethylhexyl-diglycol (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-(meth)acryloyloxyethylhexahydrophthalic acid, butoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, Methoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypropylene glycol (meth)acrylate, phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate ) acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl phthalate, 2 - monofunctional acrylates including (meth)acryloyloxyethyl-2-hydroxyethyl-phthalic acid and t-butylcyclohexyl (meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1 , 9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, di(meth)acrylate having a bisphenol A structure, neopentylglycol hydroxypivalate ( Difunctional (meth)acrylates including meth)acrylate, polytetramethylene glycol di(meth)acrylate, polyethylene glycol diacrylate and tripropylene glycol diacrylate, and trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate. ) acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, glycerin propoxytri(meth)acrylate and pentaerythritol ethoxytetra(meth)acrylate. (meth)acrylates, oligomers having a (meth)acryloyl group, including polyester acrylate oligomers, and modified products thereof.

Examples of the modified products include ethylene oxide-modified (EO-modified) acrylates into which ethylene oxide groups are inserted and propylene oxide-modified (PO-modified) acrylates into which propylene oxide is inserted.

<Acrylate compound A with defined molecular weight and ClogP value>
In the actinic radiation-curable ink according to the present invention, a (meth)acrylate compound having a molecular weight within the range of 280 to 1500 and a ClogP value within the range of 4.0 to 7.0 is used as the radically polymerizable compound. (hereinafter also simply referred to as "(meth)acrylate compound A").

The (meth)acrylate compound A more preferably has two or more (meth)acrylate groups.

The molecular weight of the (meth)acrylate compound A is in the range of 280-1500, more preferably in the range of 300-800, as described above.

In order to stably eject the ink from the ink jet recording head, the ink viscosity at 80° C. can be 3 to 20, preferably 7 to 14 mPa·s.

By including a (meth)acrylate compound having a molecular weight of 280 or more and a gelling agent described later in the ink composition, the viscosity of the ink after landing is increased, and the penetration of the ink into the recording medium can be suppressed. , the effect of suppressing the deterioration of curability can be expected. On the other hand, by containing a (meth)acrylate compound having a molecular weight of 1500 or less, an excessive increase in the sol viscosity of the ink can be suppressed, and an improvement in gloss uniformity of the coating film can be expected.

Here, the molecular weight of the (meth)acrylate compound A can be measured using the commercially available software package 1 or 2 below.

Software Package 1: MedChem Software (Release 3.54, August 1991, Medicinal Chemistry Project, Pomona College, Claremont, Calif.);
Software package 2: Chem Draw Ultra ver. 8.0. (CambridgeSoft Corporation, USA, April 2003).

In the present invention, when the actinic ray light type ink contains the (meth)acrylate compound A as at least a part of the photopolymerizable compound, the (meth)acrylate compound having a ClogP value of less than 4.0 is added to the photopolymerizable compound. The gloss value tends to be lower than the actinic radiation curable ink used as. Therefore, it is preferable to use ink for forming an image on a recording medium having a relatively low 60° gloss value before corona discharge treatment, because the difference in gloss between the printed portion and the non-printed portion can be reduced. (Meth)acrylate compound A is more hydrophobic than (meth)acrylate compounds with a ClogP value of less than 4.0, so more gelling agent repels and moves to the surface of the cured ink film, increasing unevenness. As a result, it is considered that the gloss value of the printed portion is lowered. Furthermore, the ClogP value of (meth)acrylate compound A is more preferably within the range of 4.5 to 6.0.

Here, the "logP value" is a coefficient that indicates the affinity of an organic compound for water and 1-octanol.

The 1-octanol/water partition coefficient P is the partition equilibrium when a trace amount of the compound is dissolved as a solute in the solvent of the two liquid phases of 1-octanol and water, and is the ratio of the equilibrium concentrations of the compound in each solvent, Denote their logarithm log P to base 10. That is, the "log P value" is the logarithmic value of the 1-octanol/water partition coefficient, and is known as an important parameter representing the hydrophilicity/hydrophobicity of a molecule.

"ClogP value" is a logP value calculated by calculation. A ClogP value can be calculated by a fragment method, an atomic approach method, or the like. More specifically, to calculate the ClogP value, the fragment described in the literature (C. Hansch and A. Leo, "Substitute Constants for Correlation Analysis in Chemistry and Biology" (John Wiley & Sons, New York, 1969)) method or the following commercially available software package 1 or 2 may be used.

Software Package 1: MedChem Software (Release 3.54, August 1991, Medicinal Chemistry Project, Pomona College, Claremont, Calif.);
Software package 2: Chem Draw Ultra ver. 8.0. (CambridgeSoft Corporation, USA, April 2003).

The numerical value of the "ClogP value" referred to in the present invention is the "ClogP value" calculated using the software package 2.

The amount of the (meth)acrylate compound A contained in the ink is not particularly limited. more preferred. When the amount of the (meth)acrylate compound A is 1% by mass or more, the ink does not become too hydrophilic and the gelling agent is sufficiently dissolved in the ink, so that the ink easily undergoes a sol-gel phase transition. On the other hand, by setting the amount of the (meth)acrylate compound A to 40% by mass or less, the photopolymerization initiator can be sufficiently dissolved in the ink.

More preferred examples of the (meth)acrylate compound A include (1) a trifunctional or higher functional compound having 3 to 14 structures represented by (—C(CH ₃ )H—CH ₂ —O—) Methacrylate or acrylate compounds, and (2) bifunctional or higher methacrylate or acrylate compounds having a ring structure in the molecule are included. These (meth)acrylate compounds have high photocurability and little shrinkage when cured. Furthermore, the repeatability of the sol-gel phase transition is high.

A tri- or higher functional methacrylate or acrylate compound having 3 to 14 structures represented by (-C(CH ₃ )H-CH ₂ -O-) in the molecule means, for example, 3 or more hydroxy groups. The hydroxy group of the compound having the compound is modified with propylene oxide, and the obtained modified product is esterified with (meth)acrylic acid.

Specific examples of this compound include:
3PO-modified trimethylolpropane triacrylate Photomer 4072 (molecular weight: 471, ClogP: 4.90, manufactured by Cognis),
3PO-modified trimethylolpropane triacrylate Miramer M360 (molecular weight: 471, ClogP: 4.90, manufactured by Miwon)
etc. are included.

A bifunctional or higher methacrylate or acrylate compound having a cyclic structure in the molecule is, for example, a compound obtained by esterifying the hydroxy group of a compound having two or more hydroxy groups and a tricycloalkane with (meth)acrylic acid. .

Specific examples of this compound include:
tricyclodecane dimethanol diacrylate NK ester A-DCP (molecular weight: 304, ClogP: 4.69),
Tricyclodecane dimethanol dimethacrylate NK ester DCP (molecular weight: 332, ClogP: 5.12)
etc. are included.

Another specific example of the (meth)acrylate compound A includes 1,10-decanediol dimethacrylate NK ester DOD-N (molecular weight: 310, ClogP: 5.75, manufactured by Shin-Nakamura Chemical Co., Ltd.).

The photopolymerizable compound may further contain a photopolymerizable compound other than the (meth)acrylate compound A.

Other photopolymerizable compounds include, for example, (meth)acrylate monomers or oligomers with ClogP values less than 4.0, (meth)acrylate monomers or oligomers with ClogP values greater than 7.0, other polymerizable Oligomers, etc.

Examples of these (meth)acrylate monomers or oligomers include 4EO-modified hexanediol diacrylate (CD561, Sartomer, molecular weight 358); 3EO-modified trimethylolpropane triacrylate (SR454, Sartomer, molecular weight 429); 4EO-modified pentaerythritol tetraacrylate (SR494, manufactured by Sartomer, molecular weight 528); 6EO-modified trimethylolpropane triacrylate (SR499, manufactured by Sartomer, molecular weight 560); caprolactone acrylate (SR495B, manufactured by Sartomer, molecular weight 344); polyethylene glycol Diacrylate (NK Ester A-400, Shin-Nakamura Chemical Co., Ltd., molecular weight 508), (NK Ester A-600, Shin-Nakamura Chemical Co., Ltd., molecular weight 708); Polyethylene glycol dimethacrylate (NK Ester 9G, Shin-Nakamura Chemical Co., Ltd.) , molecular weight 536), (NK ester 14G, manufactured by Shin-Nakamura Chemical Co., Ltd.); tetraethylene glycol diacrylate (V#335HP, manufactured by Osaka Organic Chemical Co., Ltd., molecular weight 302); stearyl acrylate (STA, manufactured by Osaka Organic Chemical Co., Ltd.); phenol EO-modified acrylate (M144, manufactured by Miwon); nonylphenol EO-modified acrylate (M166, manufactured by Miwon), etc. are included.

Examples of other polymerizable oligomers include epoxy acrylates, aliphatic urethane acrylates, aromatic urethane acrylates, polyester acrylates, linear acrylic oligomers, and the like.

<Cationically polymerizable compound>
Examples of cationic polymerizable compounds applicable to the present invention include epoxy compounds, vinyl ether compounds and oxetane compounds.

The ink may contain only one cationic polymerizable compound, or may contain two or more cationic polymerizable compounds.

The epoxy compound is an aromatic epoxide, an alicyclic epoxide, an aliphatic epoxide, or the like, and aromatic epoxides and alicyclic epoxides are preferred in order to improve curability.

Aromatic epoxides can be di- or polyglycidyl ethers obtained by reacting polyhydric phenols or their alkylene oxide adducts with epichlorohydrin.

Examples of the polyhydric phenol or its alkylene oxide adduct to be reacted include bisphenol A or its alkylene oxide adduct.

The alkylene oxide in the alkylene oxide adduct can be ethylene oxide, propylene oxide, and the like.

An alicyclic epoxide can be a cycloalkane oxide-containing compound obtained by epoxidizing a cycloalkane-containing compound with an oxidizing agent such as hydrogen peroxide or peracid. The cycloalkane in the cycloalkane oxide-containing compound can be cyclohexene or cyclopentene.

Aliphatic epoxides can be di- or polyglycidyl ethers obtained by reacting an aliphatic polyhydric alcohol or its alkylene oxide adduct with epichlorohydrin.

Examples of aliphatic polyhydric alcohols include ethylene glycol, propylene glycol, alkylene glycols such as 1,6-hexanediol, and the like. The alkylene oxide in the alkylene oxide adduct can be ethylene oxide, propylene oxide, and the like.

Examples of vinyl ether compounds include ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexanedimethanol monovinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, isopropenyl ether. - monovinyl ether compounds such as o-propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, octadecyl vinyl ether;
Diethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, trimethylolpropane trivinyl ether, etc. or trivinyl ether compounds. Among these vinyl ether compounds, di- or tri-vinyl ether compounds are preferred in consideration of curability and adhesion.

The oxetane compound is a compound having an oxetane ring, and examples thereof include the oxetane compounds described in JP-A-2001-220526, JP-A-2001-310937, JP-A-2005-255821, and the like. . Among them, the compound represented by the general formula (1) described in paragraph number (0089) of JP-A-2005-255821, the general formula (2) described in paragraph number (0092) of the same publication compound, the compound represented by the general formula (7) described in paragraph number (0107) of the same publication, the compound represented by the general formula (8) described in paragraph number (0109) of the same publication, the same number Compounds represented by the general formula (9) described in paragraph number (0116) of the publication, and the like.

(Gelling agent)
The actinic radiation curable ink according to the present invention contains a gelling agent, the gelation temperature is equal to or higher than the LCST of the heat-sensitive responsive polymer contained in the transfer body, and the gel state can be obtained at the gelation temperature or lower. preferable.

The gelling agent has a function of temporarily fixing (pinning) the ink droplets that have landed on the transfer base material in a gel state. When an ink containing a gelling agent is pinned in a gel state, the wetting and spreading of the ink is suppressed, making it difficult for adjacent dots to coalesce, so that a higher definition image can be formed.

The gelling agent preferably crystallizes at a temperature below the gelling temperature of the actinic radiation curable ink. The gelation temperature is the temperature at which the gelling agent undergoes a phase transition from sol to gel and the viscosity of the ink suddenly changes when the ink that has been solified or liquefied by heating is cooled. Specifically, the solified or liquefied ink is cooled while measuring the viscosity with a viscoelasticity measuring device (e.g., MCR300, manufactured by Anton Paar). It can be the gelling temperature of the ink.

When the gelling agent is crystallized in the ink, a so-called card house structure is formed in which the photopolymerizable compound is enclosed in a three-dimensional space formed by the plate-like crystallized gelling agent. When the card house structure is formed, the liquid photopolymerizable compound is held in the three-dimensional space, so that the ink droplets are more difficult to spread and the ink pinning property is further enhanced. When the pinning property of the ink is enhanced, it becomes difficult for the ink droplets that have landed on the recording medium to coalesce, and a higher definition image can be formed.

In order to form the card house structure, it is preferable that the photopolymerizable compound dissolved in the ink and the gelling agent are compatible with each other.

Examples of gelling agents suitable for forming card house structures include aliphatic ketones, aliphatic esters, petroleum waxes, vegetable waxes, animal waxes, mineral waxes, hydrogenated castor oil, modified waxes, higher fatty acids, Included are higher alcohols, hydroxystearic acid, fatty acid amides including N-substituted fatty acid amides and special fatty acid amides, higher amines, esters of sucrose fatty acids, synthetic waxes, dibenzylidene sorbitol, dimer acid and dimer diols. Among them, aliphatic ketones, aliphatic esters, higher fatty acids, and higher alcohols having a hydrocarbon group of 9 to 25 carbon atoms are preferred from the viewpoint of further enhancing pinning properties. The ink may contain only one gelling agent, or may contain two or more gelling agents.

Examples of aliphatic ketones include dilignoceryl ketone, dibehenyl ketone, distearyl ketone, dieicosil ketone, dipalmityl ketone, dilauryl ketone, dimyristyl ketone, myristyl palmityl ketone and palmityl stearyl ketone. be

Examples of fatty esters include fatty acid esters of monoalcohols such as behenyl behenate, icosyl icosanoate, oleyl palmitate; glycerin fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, ethylene glycol fatty acid esters and polyoxyethylene fatty acid esters. fatty acid esters of polyhydric alcohols such as

Examples of commercially available products of the above-mentioned aliphatic esters include EMALEX series, manufactured by Nippon Emulsion Co., Ltd. ("EMALEX" is a registered trademark of the same company), Rikemal series and Poem series, manufactured by Riken Vitamin Co., Ltd. ("Rikemal" and "Poem" are Both are registered trademarks of the company).

Examples of higher fatty acids include behenic acid, arachidic acid, stearic acid, palmitic acid, myristic acid, lauric acid, oleic acid, and erucic acid.

Examples of higher alcohols include stearyl alcohol and behenyl alcohol.

Among them, in the present invention, an aliphatic ketone represented by the following general formula (G1) or an aliphatic ester represented by the following general formula (G2) is particularly preferable as the gelling agent.

General formula (G1): R ₁ —CO—R ₂
In general formula (G1), R ₁ and R ₂ each independently represent an alkyl group containing a linear portion having 12 to 26 carbon atoms and which may contain a branch. R ₁ and R ₂ may be the same or different.

General formula (G2): R ₃ —COO—R ₄
In general formula (G2), R ₃ and R ₄ each independently represent an alkyl group containing a linear portion having 12 to 26 carbon atoms and which may contain a branch. R ₃ and R ₄ may be the same or different.

In the general formulas (G1) and (G2), since the number of carbon atoms in the linear or branched hydrocarbon group is 12 or more, the aliphatic ketone represented by the general formula (G1) or the general formula (G2) The aliphatic ester represented by is more crystalline and more space is created in the card house structure. Therefore, the photopolymerizable compound is likely to be sufficiently included in the space, and the pinning property of the ink is further enhanced. Since the linear or branched hydrocarbon group has 26 or less carbon atoms, the aliphatic ketone represented by the general formula (G1) and the aliphatic ester represented by the general formula (G2) have a melting point of It does not build up too much and there is no need to overheat the ink when ejecting it.

Examples of aliphatic ketones represented by the general formula (G1) include dilignoceryl ketone (carbon number: 23-24), dibehenyl ketone (carbon number: 21-22), distearyl ketone (carbon number: 17 ~ 18), dieicosilketone (carbon number: 19-20), dipalmityl ketone (carbon number: 15-16), dimyristyl ketone (carbon number: 13-14), dilauryl ketone (carbon number: 11 ~ 12), lauryl myristyl ketone (carbon number: 11-14), lauryl palmityl ketone (carbon number: 11-16), myristyl palmityl ketone (carbon number: 13-16), myristyl stearyl ketone (carbon number: 13 ~ 18), myristyl behenyl ketone (carbon number: 13-22), palmityl stearyl ketone (carbon number: 15-18), palmityl behenyl ketone (carbon number: 15-22) and stearyl behenyl ketone (carbon number: 17 22) are included. The number of carbon atoms in parentheses represents the number of carbon atoms in each of the two hydrocarbon groups separated by the carbonyl group.

Examples of commercially available aliphatic ketones represented by the general formula (G1) include 18-Pentatriacontanon, manufactured by Alfa Aeser, Hentriacontan-16-on, manufactured by Alfa Aeser, and Kaowax T-1, manufactured by Kao Corporation. included.

Examples of aliphatic esters represented by the general formula (G2) include behenyl behenate (carbon number: 21 to 22), icosyl icosanoate (carbon number: 19 to 20), stearyl stearate (carbon number: 17 to 18), palmityl stearate (carbon number: 17-16), lauryl stearate (carbon number: 17-12), cetyl palmitate (carbon number: 15-6), stearyl palmitate (carbon number: 15-18) , myristyl myristate (carbon number: 13-14), cetyl myristate (carbon number: 13-16), octyldodecyl myristate (carbon number: 13-20), stearyl oleate (carbon number: 17-18), stearyl erucate (carbon number: 21-18), stearyl linoleate (carbon number: 17-18), behenyl oleate (carbon number: 18-22) and arachidyl linoleate (carbon number: 17-20) . The number of carbon atoms in parentheses represents the number of carbon atoms in each of the two hydrocarbon groups separated by the ester group.

Examples of commercially available aliphatic esters represented by the general formula (G2) include Unistar M-2222SL and Spermaceti, manufactured by NOF Corporation ("Unistar" is a registered trademark of the same company), Excepar SS and Excepar MY-M, Manufactured by Kao Corporation ("Exepar" is a registered trademark of the same company), EMALEX CC-18 and EMALEX CC-10, manufactured by Nihon Emulsion Co., Ltd. ("EMALEX" is a registered trademark of the same company), Amleps PC, manufactured by Kokyu Alcohol Kogyo Co., Ltd. ("Amleps ” is a registered trademark of the company).

The content of the gelling agent is preferably in the range of 1.0 to 10.0% by weight with respect to the total weight of the ink. By setting the content of the gelling agent to 1.0% by mass or more, the pinning property of the ink can be sufficiently enhanced, and a higher definition image can be formed. In addition, by increasing the pinning property of the ink, it is possible to suppress insufficient color development caused by the ink penetrating into the inside of the recording medium, particularly when an image is formed on a water-absorbing recording medium. By setting the content of the gelling agent to 10.0% by mass or less, precipitation of the gelling agent from the surface of the formed image can be suppressed, and the ejection property of the ink from the inkjet head is less likely to be impaired.

The content of the gelling agent is more preferably in the range of 1.0 to 7.0% by mass, more preferably in the range of 1.1 to 5.0% by mass, relative to the total mass of the ink. More preferably, it is most preferably within the range of 1.3 to 4.0% by mass.

(Photoinitiator)
The actinic radiation-curable ink containing a photopolymerizable compound according to the present invention contains a photopolymerization initiator. The photopolymerization initiator is a photoradical initiator when the photopolymerizable compound is a radically polymerizable compound, and a photoacid generator when the photopolymerizable compound is a cationically polymerizable compound.

Only one photopolymerization initiator may be contained in the ink, or two or more kinds thereof may be contained. The photoinitiator may be a combination of both a photoradical initiator and a photoacid generator.

Photoradical initiators may include cleavage radical initiators or hydrogen abstraction radical initiators.

Examples of cleavable radical initiators include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, 1-(4-isopropylphenyl)-2-hydroxy-2- Methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl-phenylketone, 2-methyl-2-morpholino(4-thiomethylphenyl) acetophenone initiators including propan-1-one and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone; benzoin initiators including benzoin, benzoin methyl ether and benzoin isopropyl ether; Included are acylphosphine oxide initiators, including 2,4,6-trimethylbenzoin diphenylphosphine oxide, benzyl and methylphenyl glyoxyesters.

Examples of hydrogen abstraction type radical initiators include benzophenone, methyl-4-phenylbenzophenone o-benzoylbenzoate, 4,4′-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4′-methyl-diphenylsulfide, acrylated Benzophenone initiators, including benzophenone, 3,3′,4,4′-tetra(t-butylperoxycarbonyl)benzophenone and 3,3′-dimethyl-4-methoxybenzophenone, 2-isopropylthioxanthone, 2,4- thioxanthone initiators including dimethylthioxanthone, 2,4-diethylthioxanthone and 2,4-dichlorothioxanthone; aminobenzophenone initiators including Michler's ketone and 4,4'-diethylaminobenzophenone; 10-butyl-2-chloroacrylate Included are don, 2-ethylanthraquinone, 9,10-phenanthrenequinone and camphorquinone.

Examples of photoacid generators include the compounds described in "Organic Materials for Imaging", edited by Organic Electronics Materials Research Group, Bunshin Publishing (1993), pp. 187-192.

The content of the photopolymerization initiator may be within a range that allows the photopolymerizable compound to be sufficiently cured, and may be, for example, within the range of 0.01 to 10% by mass relative to the total mass of the ink.

(Other additives)
The actinic radiation curable ink applied to the present invention further contains other components such as a photopolymerization initiator aid, a polymerization inhibitor, a polymer dispersant, and a surfactant within the range in which the effects of the present invention can be obtained. You can

<Photopolymerization initiator aid and polymerization inhibitor>
The actinic radiation curable ink applied to the present invention may further contain a photopolymerization initiator aid, a polymerization inhibitor, and the like, if necessary.

The photoinitiator aid may be a tertiary amine compound, preferably an aromatic tertiary amine compound. Examples of aromatic tertiary amine compounds include N,N-dimethylaniline, N,N-diethylaniline, N,N-dimethyl-p-toluidine, N,N-dimethylamino-p-benzoic acid ethyl ester, N,N-dimethylamino-p-benzoic acid isoamylethyl ester, N,N-dihydroxyethylaniline, triethylamine and N,N-dimethylhexylamine and the like. Among them, N,N-dimethylamino-p-benzoic acid ethyl ester and N,N-dimethylamino-p-benzoic acid isoamylethyl ester are preferred. These compounds may be used alone, or two or more of them may be used in combination.

Examples of polymerization inhibitors include (alkyl)phenol, hydroquinone, catechol, resorcinol, p-methoxyphenol, t-butylcatechol, t-butylhydroquinone, pyrogallol, 1,1-picrylhydrazyl, phenothiazine, p-benzoquinone. , nitrosobenzene, 2,5-di-t-butyl-p-benzoquinone, dithiobenzoyl disulfide, picric acid, cupferron, aluminum N-nitrosophenylhydroxylamine, tri-p-nitrophenylmethyl, N-(3-oxyanilino- 1,3-dimethylbutylidene)aniline oxide, dibutyl cresol, cyclohexanone oxime cresol, guaiacol, o-isopropylphenol, butyraldoxime, methyl ethyl ketoxime, cyclohexanone oxime and the like.

<Polymer dispersant>
Examples of polymeric dispersants include hydroxy group-containing carboxylic acid esters, salts of long-chain polyaminoamides and high-molecular-weight acid esters, salts of high-molecular-weight polycarboxylic acids, salts of long-chain polyaminoamides and polar acid esters, high-molecular-weight unsaturated acid ester, polymer copolymer, modified polyurethane, modified polyacrylate, polyether ester type anionic active agent, naphthalenesulfonic acid formalin condensate salt, aromatic sulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphate, polyoxyethylene nonylphenyl ether, stearylamine acetate and the like.

Moreover, as a polymeric dispersant, for example, a comb-shaped block copolymer having a basic group may be used.

A comb-shaped block copolymer in a comb-shaped block copolymer having a basic group is a linear polymer that forms the main chain, and a graft polymerization of each structural unit derived from a monomer that constitutes the linear main chain. It refers to a copolymer having another type of polymer that has

As the side chain, a long-chain polyoxyalkyl group (EO-PO copolymer group) is preferred. Examples of comb block copolymers include those in which the main chain is a polymer of acrylic ester and the side chains are long-chain polyoxyalkyl groups (EO-PO copolymerization groups).

The basic groups in the comb block copolymer having basic groups are preferably quaternary, tertiary, secondary or primary amine groups.

The weight average molecular weight of the polymeric dispersant is preferably in the range of 1,000 to 50,000, more preferably in the range of 5,000 to 30,000. The weight-average molecular weight of the polymer dispersant can be determined by gel permeation chromatography (GPC method) in terms of polystyrene.

Commercially available examples of polymeric dispersants containing basic groups include DISPERBYK-109, 161, 168, 180, 2013, 2155, BYKJET-9150 and BYKJET-9151 from BYK; Efka-4431 from BASF. , PX4701; PB-821, 822, 824 manufactured by Ajinomoto Fine-Techno; Solsperse 24000GR, 32000, 39000, 71000 and J-200 manufactured by Lubrizol. "DISPERBYK" and "BYKJET" are registered trademarks of BYK, "Efka" is a registered trademark of BASF, and "Solsperse" is a registered trademark of Lubrizol.

When the colorant is a pigment, the content of the polymeric dispersant is preferably in the range of 30 to 70% by weight with respect to the total weight of the pigment. When the content of the polymer dispersant is 30% by mass or more with respect to the pigment, not only can the aggregation of the pigment be more difficult to occur, but also the interaction between the pigment and the gelling agent can be effectively suppressed, Gloss variation and dot diameter variation under high temperature storage can be further suppressed. When the content of the polymer dispersant is more than 70% by mass with respect to the pigment, excess polymer dispersant that does not contribute to pigment dispersion causes gelation inhibition, and the initial gloss value and initial dot diameter increase. put away.

More preferably, the content of the polymeric dispersant is in the range of 35 to 65% by weight with respect to the total weight of the pigment.

The inkjet ink of the present invention may contain only one polymer dispersant, or may contain two or more polymer dispersants.

The pigment and polymer dispersant can be dispersed by, for example, a ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill or paint shaker.

<Surfactant>
Examples of surfactants include anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates and fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols and polyoxy Nonionic surfactants such as ethylene/polyoxypropylene block copolymers, cationic surfactants such as alkylamine salts and quaternary ammonium salts, and silicone-based and fluorine-based surfactants are included.

Examples of silicone-based surfactants include polyether-modified polysiloxane compounds, specifically KF-351A, KF-352A, KF-642 and X-22-4272, manufactured by Shin-Etsu Chemical Co., Ltd., BYK307, BYK345, Included are BYK347 and BYK348, manufactured by Big Chemie (“BYK” is a registered trademark of the Company), and TSF4452, manufactured by Momentive Performance Materials.

A fluorosurfactant means a surfactant in which some or all of the hydrogen atoms in the hydrophobic groups of ordinary surfactants are replaced with fluorine. Examples of fluorine-based surfactants include Megafac F, manufactured by DIC ("Megafac" is a registered trademark of the same company), Surflon, manufactured by AGC Seichemical ("Surflon" is a registered trademark of the same company), Fluorad FC, 3M (“Fluorad” is a registered trademark of the same company), Monflor, Imperial Chemical Industry, Zonyls, EI Dupont de Nemours & Company, Licowet VPF, Lubewerke Hoechst, and FTERGENT, manufactured by Neos (“FTERGENT” is a registered trademark of the same company).

The amount of surfactant can be arbitrarily set within the range where the effects of the present invention can be obtained. The amount of surfactant can be, for example, 0.001% by mass or more and less than 1.0% by mass with respect to the total mass of the ink.

(colorant)
As the coloring material applicable to the actinic radiation curable ink according to the present invention, dyes or pigments can be applied, and have good dispersibility in the constituent components of the ink and excellent weather resistance. , pigments are more preferred.

<dye>
As the dye, an oil-soluble dye or the like can be applied. Oil-soluble dyes include the following various dyes. Examples of magenta dyes include MS Magenta VP, MS Magenta HM-1450, MS Magenta HSo-147 (manufactured by Mitsui Toatsu Co., Ltd.), AIZEN SOT Red-1, AIZEN SOT Red-2, AIZEN SOT Red-3, and AIZEN SOT. Pink-1, SPIRON Red GEH SPECIAL (manufactured by Hodogaya Chemical Co., Ltd.), RESOLIN Red FB 200%, MACROLEX Red Violet R, MACROLEX ROT5B (manufactured by Bayer Japan), KAYASET Red B, KAYASET Red 130, KAYASET Red 802 (manufactured by Nippon Kayaku), PHLOXIN, ROSE BENGAL, ACID Red (manufactured by Daiwa Kasei), HSR-31, DIARESIN Red K (manufactured by Mitsubishi Kasei), Oil Red (manufactured by BASF Japan) ) is included.

Examples of cyan dyes include MS Cyan HM-1238, MS Cyan HSo-16, Cyan HSo-144, MS Cyan VPG (manufactured by Mitsui Toatsu Co., Ltd.), AIZEN SOT Blue-4 (manufactured by Hodogaya Chemical Co., Ltd.), RESOLIN BR. Blue BGLN 200%, MACROLEX Blue RR, CERES Blue GN, SIRIUS SUPRATURQ. Blue Z-BGL, SIRIUS SUPRA TURQ. Blue FB-LL 330% (manufactured by Bayer Japan), KAYASET Blue FR, KAYASET Blue N, KAYASET Blue 814, Turq. Blue GL-5 200, Light Blue BGL-5 200 (manufactured by Nippon Kayaku), DAIWA Blue 7000, Oleosol Fast Blue GL (manufactured by Daiwa Kasei), DIARESIN Blue P (manufactured by Mitsubishi Kasei), SUDAN Blue 670, NEOPEN Blue 808, ZAPON Blue 806 (manufactured by BASF Japan Ltd.) and the like are included.

Examples of yellow dyes include MS Yellow HSm-41, Yellow KX-7, Yellow EX-27 (Mitsui Toatsu), AIZEN SOT Yellow-1, AIZEN SOT YellowW-3, AIZEN SOT Yellow-6 (above, Hodogaya chemical company), MACROLEX Yellow 6G, MACROLEX FLUOR. Yellow 10GN (manufactured by Bayer Japan), KAYASET Yellow SF-G, KAYASET Yellow 2G, KAYASET Yellow AG, KAYASET Yellow EG (manufactured by Nippon Kayaku), DAIWA Yellow 330HB (manufactured by Daiwa Kasei) , HSY-68 (manufactured by Mitsubishi Kasei Corporation), SUDAN Yellow 146, NEOPEN Yellow 075 (manufactured by BASF Japan Ltd.) and the like.

Examples of black dyes include MS Black VPC (manufactured by Mitsui Toatsu Co., Ltd.), AIZEN SOT Black-1, AIZEN SOT Black-5 (manufactured by Hodogaya Chemical Co., Ltd.), Resorin Black GSN 200%, RESOLIN Black BS (manufactured by Hodogaya Chemical Co., Ltd.). Bayer Japan), KAYASET Black AN (manufactured by Nippon Kayaku), DAIWA Black MSC (manufactured by Daiwa Kasei), HSB-202 (manufactured by Mitsubishi Kasei), NEPTUNE Black X60, NEOPEN Black X58 (above, BASF Japan), etc. are included.

<Pigments>
It is preferable to apply a pigment as a coloring material to the actinic radiation-curable ink according to the present invention, and the pigment is not particularly limited. Inorganic pigments may be mentioned.

Examples of red or magenta pigments include Pigment Red 3, 5, 19, 22, 31, 38, 43, 48:1, 48:2, 48:3, 48:4, 48:5, 49:1, 53 : 1, 57:1, 57:2, 58:4, 63:1, 81, 81:1, 81:2, 81:3, 81:4, 88, 104, 108, 112, 122, 123, 144 , 146, 149, 166, 168, 169, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, Pigment Orange 13, 16, 20, 36, etc. are included. Examples of blue or cyan pigments include Pigment Blue 1, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17-1, 22, 27, 28, 29, 36 , 60 and the like. Examples of green pigments include Pigment Green 7, 26, 36, 50. Examples of yellow pigments include Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 137 , 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193, etc. Examples of black pigments include Pigment Black 7, 28, 26, and the like.

Commercially available examples of pigments include Chromofine Yellow 2080, 5900, 5930, AF-1300, 2700L, Chromofine Orange 3700L, 6730, Chromofine Scarlet 6750, Chromofine Magenta 6880, 6886, 6891N, 6790, 6887, Chromofine Fine Violet RE, Chromo Fine Red 6820, 6830, Chromo Fine Blue HS-3, 5187, 5108, 5197, 5085N, SR-5020, 5026, 5050, 4920, 4927, 4937, 4824, 4933 GN-EP, 4940, 4973, 5205, 5208, 5214, 5221, 5000P, Chromo Fine Green 2GN, 2GO, 2G-550D, 5310, 5370, 6830, Chromo Fine Black A-1103, Seika Fast Yellow 10GH, A-3, 2035, 2054, 2200, 2270 , 2300, 2400 (B), 2500, 2600, ZAY-260, 2700 (B), 2770, Seika Fast Red 8040, C405 (F), CA120, LR-116, 1531B, 8060R, 1547, ZAW-262, 1537B , GY, 4R-4016, 3820, 3891, ZA-215, Seika Fast Carmin 6B1476T-7, 1483LT, 3840, 3870, Seika Fast Bordeaux 10B-430, Seika Light Rose R40, Seika Light Violet B800, 7805, Seika Fast Maroon 460N, Seika Fast Orange 900, 2900, Seika Light Blue C718, A612, Cyanine Blue 4933M, 4933GN-EP, 4940, 4973 (manufactured by Dainichiseika Kogyo);
KET Yellow 401, 402, 403, 404, 405, 406, 416, 424, KET Orange 501, KET Red 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 336, 337, 338, 346, KET Blue 101, 102, 103, 104, 105, 106, 111, 118, 124, KET Green 201 (manufactured by Dainippon Ink and Chemicals);
Colortex Yellow 301, 314, 315, 316, P-624, 314, U10GN, U3GN, UNN, UA-414, U263, Finecol Yellow T-13, T-05, Pigment Yellow 1705, Colortex Orange 202, Colortex Red 101, 103, 115, 116, D3B, P-625, 102, H-1024, 105C, UFN, UCN, UBN, U3BN, URN, UGN, UG276, U456, U457, 105C, USN, Colortex Maroon601, Colortex BrownB610N, Colortex Vi olet600, Pigment Red 122, Colortex Blue516, 517, 518, 519, A818, P-908, 510, Colortex Green402, 403, Colortex Black 702, U905 (manufactured by Sanyo Pigment);
Lionol Yellow1405G, Lionol Blue FG7330, FG7350, FG7400G, FG7405G, ES, ESP-S (manufactured by Toyo Ink), Toner Magenta E02, Permanent RubinF6B, Toner Yellow HG, Permanent Yellow GG- 02, Hostapeam Blue B2G (manufactured by Hoechst Industry);
Novoperm P-HG, Hostaperm Pink E, Hostaperm Blue B2G (manufactured by Clariant);
Carbon black #2600, #2400, #2350, #2200, #1000, #990, #980, #970, #960, #950, #850, MCF88, #750, #650, MA600, MA7, MA8, MA11 , MA100, MA100R, MA77, #52, #50, #47, #45, #45L, #40, #33, #32, #30, #25, #20, #10, #5, #44, CF9 (manufactured by Mitsubishi Chemical) and the like.

Titanium oxide (particularly rutile-type titanium dioxide) can also be used as the white pigment.

The volume average particle size of the pigment is preferably 0.1 to 0.5 μm. The maximum particle size of the pigment is preferably 0.1-1.0 μm, more preferably 0.1-0.5 μm, and most preferably 0.2-0.5 μm. By adjusting the particle size of the pigment, clogging of the nozzles of the inkjet recording head can be suppressed, and the storage stability, ink transparency and curing sensitivity of the ink can be maintained.

In the present invention, the amount of the coloring material contained in the actinic radiation curable ink is preferably in the range of 0.1 to 20% by mass, more preferably in the range of 0.4 to 10% by mass with respect to the total mass of the ink. is more preferable. This is because if the content of the pigment or dye is too small, the color development of the obtained image is not sufficient, and if the content is too large, the viscosity of the ink increases and the ejection property deteriorates.

《Inkjet image forming device》
Next, an inkjet image forming apparatus using the transfer member of the present invention and an inkjet image forming method will be described.

FIG. 2 is a schematic configuration diagram showing an example of an inkjet image forming apparatus equipped with the transfer member of the present invention.

In FIG. 2, an endless belt-shaped transfer body is used as the transfer body, and the transfer body has a heat-sensitive responsive polymer that changes the contact angle due to thermal stimulation as an external stimulus. An example using ink is shown.

In FIG. 2, the inkjet image forming apparatus (8) is a transfer type inkjet image forming apparatus using an inkjet printing method. An inkjet image forming apparatus (8) mainly includes a head carriage (10) on which inkjet heads of respective colors are mounted, a transfer section (20), a recording medium transport roller (30), a light irradiation section (50), It is composed of a heating section (H), a cooling section (C), and a control section (not shown).

As shown in FIG. 2, the head carriage (10) is equipped with inkjet heads (11Y, 11C, 11M, 11K) of respective colors, and Y (yellow), M (magenta), C (cyan), and K (black). Ink of each color is ejected onto the transfer member (1) to form an image based on the ink (corresponding to step b). At this stage, the surface of the transfer member (1) is hydrophilic, and the ink droplets that have landed are wetted and spread (corresponding to step c).

The ink ejected from each inkjet head (11) may be a water-based ink containing water and optionally a small amount of organic solvent as liquid components, or may contain an organic solvent as a liquid component but is substantially water-based. It may be a solvent-based ink that does not contain, or an actinic radiation-curable ink that contains a photopolymerizable compound that cures by polymerizing and cross-linking when irradiated with actinic rays such as ultraviolet rays and electron beams as a liquid component. It can be. The configuration shown in FIG. 2 shows an example in which the ink ejected from the inkjet head (11) is actinic radiation curable ink.

The transfer section (20) has, for example, a belt-like transfer body (1) and three belt support rollers (22, 23, 24). A belt-shaped transfer body (1) is composed of an endless belt, and is stretched in an inverted triangular shape around three belt support rollers (22, 23, 24). The belt-shaped transfer body (1) according to the present invention comprises at least a transfer substrate made of a resin material such as polyimide, and a heat-sensitive responsive polymer or the like whose contact angle changes with an external stimulus on the transfer substrate. It has a thermally responsive layer containing:

At least one of the three support rollers (22, 23, 24) is a drive roller and is driven under the control of a controller (not shown). As a result, the belt-shaped transfer body (1) is conveyed in the arrow direction (clockwise direction in FIG. 2).

Ink ejected from each inkjet head (11) lands on the portions of the belt-shaped transfer body (1) stretched between the belt support rollers (22 and 24) located at the left and right vertices of the inverted triangle. It is a face.

On the downstream side of step b, a heat treatment is applied to the belt-shaped transfer body (1) on which the ink has landed in the region stretched over the belt support rollers (22 and 23) of the belt-shaped transfer body (1). A heating portion (H) is provided for enlarging the contact angle of the ink by hydrophobizing the heat-sensitive polymer of the heat-sensitive layer by applying a heat-sensitive layer (corresponding to step d).

Furthermore, on the downstream side, a belt support roller (23) is arranged at the vertex of the lower side of the inverted triangle of the belt-like transfer body (1). It functions as a pressure roller that presses the body (1) toward the recording medium transport roller (30) with a predetermined nip pressure.

A recording medium transport roller (30) which is arranged at a position facing the belt support roller (23) and holds the recording medium which is a transfer target, is composed of a metal drum and is pressed by the belt support roller (23). Thus, a transfer nip is formed. The recording medium transport roller (30) has a claw (not shown) that fixes the leading edge of the recording medium (5). Under the control of a control unit (not shown), the recording medium transport roller (30) fixes the tip of the recording medium (5) to the claw and rotates counterclockwise in FIG. 5) is conveyed to the transfer nip (step e).

The inkjet image formed by the actinic radiation curable ink transferred onto the recording medium (5) is irradiated with, for example, ultraviolet rays from the actinic radiation irradiation unit (50) to cure the inkjet image.

Next, on the downstream side of step d, the belt-shaped transfer body (1) stretched over the belt support rollers (23 and 24) is filled with the belt-shaped transfer material that has completed the transfer onto the recording medium (5). The body (1) is provided with a cleaning section (CL) for removing the ink-jet image remaining on its surface during transfer. For the cleaning section, a method of physically peeling off the residual ink image on the transfer body is effective. Examples include a method of removing the remaining ink image using a brush and a method of removing the remaining ink image using an adhesive roller or a sponge roller.

Next, the transfer body whose surface has been cleaned is cooled by the cooling section (C) to the lower critical solution temperature (LCST) or lower of the heat-sensitive responsive polymer containing the belt-shaped transfer body (1). As a result, the surface properties of the thermoresponsive layer are changed from hydrophobic to hydrophilic in the initial state, completing one cycle (corresponding to step a).

In the above description, the ink jet image forming method using heat stimulation as an external stimulation was described. In the case of using a photosensitive polymer whose state changes from hydrophilic to hydrophobic, as shown in FIG. A preliminary light irradiation unit (51) is provided to perform the above, and after making the transfer body hydrophilic by light irradiation in advance, ink is discharged, and then hydrophobization and transfer are performed by heat treatment by the heating unit (H). can also

The inkjet head used in the inkjet image forming method may be of an on-demand system or a continuous system. In addition, as a discharge method, an electro-mechanical conversion method (eg, single cavity type, double cavity type, bender type, piston type, share mode type, shared wall type, etc.), an electro-thermal conversion method (eg, thermal Specific examples include inkjet type, bubble jet (registered trademark) type, etc.), electrostatic attraction type (e.g., electric field control type, slit jet type, etc.), discharge type (e.g., spark jet type, etc.), and the like. However, any ejection method may be used. Moreover, as a printing method, a serial head method, a line head method, or the like can be used without limitation.

As an inkjet head, for example, JP-A-2012-140017, JP-A-2013-010227, JP-A-2014-058171, JP-A-2014-097644, JP-A-2015-142979, JP-A-2015 -142980, JP-A-2016-002675, JP-A-2016-002682, JP-A-2016-107401, JP-A-2017-109476, JP-A-2017-177626, etc. An inkjet head having a configuration can be appropriately selected and applied.

When the actinic ray irradiation unit (50) or the preliminary light irradiation unit (51) is an actinic ray irradiation unit (50) or a preliminary light irradiation unit (51), when the actinic ray is an ultraviolet ray, an example of the actinic ray irradiation light source is a fluorescent tube (e.g., a low-pressure mercury lamp). , germicidal lamps, etc.), cold-cathode tubes, ultraviolet lasers, low-pressure, medium-pressure, and high-pressure mercury lamps with an operating pressure of several hundred Pa to 1 MPa, metal halide lamps, and LEDs. From the viewpoint of curability, an ultraviolet irradiation means that irradiates ultraviolet rays with an illuminance of 100 mW/cm ² or more, specifically, a high-pressure mercury lamp, a metal halide lamp, or an LED is preferable, and an LED is more preferable from the viewpoint of low power consumption. preferable. Specifically, a water-cooled LED manufactured by Phoseon Technology (wavelength: 395 nm) can be used.

As the heating means constituting the heating section (H), known means such as heated hot air, high-temperature water heating, electric heaters, and microwaves can be applied.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited thereto. In the examples, "parts" or "%" are used, but "mass parts" or "mass%" are indicated unless otherwise specified. Moreover, unless otherwise specified, each operation was performed at room temperature (25° C.).

《Preparation of printed matter》
[Preparation of printed matter 1]
[Preparation of transfer member 1]
A polyimide film (thickness: 40 μm) was used as the transfer substrate, and corona discharge (corona output intensity: 2.0 kW, line speed: 18 m/min) was applied to the transfer substrate surface to activate the transfer substrate surface. After that, a 5.0% by mass ethanol solution of aminopropyltriethoxysilane was sprayed, followed by a 3.0% aqueous ammonia solution, followed by drying at 80° C. for 1 hour.

The polyimide film was then immersed in a dichloromethane solution of 2-bromoisobutyryl bromide and triethylamine and allowed to stand at 25° C. for 12 hours. After that, the polyimide film was spray-washed with dichloromethane and dried. The resulting polyimide film was immersed in a methanol/water solution containing N-isopropylacrylamide, N,N,N',N″,N″-pentamethyldiethylenetriamine, and copper(I) chloride/copper(II) bromide. and allowed to stand at 25° C. for 5 hours. The resulting polyimide film was spray-washed with methanol and then dried at 55° C. for 30 minutes to prepare a transfer member 1 having poly(N-isopropylacrylamide) as a thermosensitive polymer. The lower critical solution temperature (LCST) of poly(N-isopropylacrylamide), which is a thermosensitive polymer, is 35°C.

[Preparation of ink 1: water-based dye ink]
As a dispersant, DISPERBYK-190 (manufactured by BYK-Chemie, comb-shaped block polymer dispersant, acid value: 10 mgKOH/g, solid content: 40%) and ion-exchanged water were stirred and mixed until uniform, and then, as a cyan dye, After adding Disperse Blue-60 (disperse dye) and premixing, dynamic light scattering was performed using Zetasizer 1000 (manufactured by Malvern) in a sand grinder filled with 50% by volume of 0.5 mm zirconia beads. Dispersion liquid 1 was prepared by dispersing until the Z-average particle diameter measured by the method reached 130 nm and having a coloring material solid content of 20% by mass.

Then, 10 parts by weight of dispersion liquid 1, 5 parts by weight of ethylene glycol (EG) as a solvent, 3 parts by weight of propylene glycol (PG) and 1 part by weight of glycerin (GLY), and KF as a silicone surfactant 0.2 parts by mass of -351A (manufactured by Shin-Etsu Chemical Co., Ltd.), 0.2 parts by mass of Proxel GXL (manufactured by Arch Chemicals Japan) as an antifungal agent, and 80.6 parts by mass of ion-exchanged water , mixed and stirred to make it uniform, and then filtered through a 1 μm mesh filter to obtain Ink 1.

[Measurement of contact angle]
Next, the contact angle of ink 1 with respect to transfer member 1 at 25° C. and 50° C. was measured by the following method.

The contact angle of the ink 1 with respect to the surface of the transfer body 1 was measured based on JIS-R3257 under an atmosphere of 25° C. and 55% RH and under an atmosphere of 50° C. and 55% RH. were kept at 25° C. and 50° C., respectively, and 1 μL of ink 1 was dropped using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., trade name DropMaster DM100), and the contact angle was measured after 1 minute. The measurements were made at arbitrary 10 points on the transfer member 1, and the average value was obtained. As a result of measurement by the above method, the contact angle of the ink 1 with respect to the transfer member 1 at 25° C. was 38 degrees, and the contact angle at 50° C. was 65 degrees. could be confirmed.

[Formation of inkjet image]
Using a Peltier cooling/heating unit, the ink 1 is ejected from an inkjet recording apparatus having an inkjet recording head equipped with a piezo inkjet nozzle onto the transfer body 1 set at 25° C. to form an image, and then transferred to the Peltier heating unit. While the transfer body 1 is heated to 45° C. (LCST temperature or higher), pressure transfer is performed on printing coated paper A (OK top coat, basis weight 128 g/m ² manufactured by Oji Paper Co., Ltd.) as a recording medium. , and heat drying at 80° C. for 15 seconds to produce a printed matter 1 .

[Preparation of printed matter 2]
Printed Matter 2 was produced in the same manner as above except that Transfer Body 1 was used, Ink 1 was changed to Ink 2 described below, and the formation of the inkjet image was changed to the formation method described below. was made.

[Preparation of ink 2: solvent-based dye ink]
20 parts by mass of Disperse Blue-60 as a cyan dye, DISPERBYK-111 (acidic dispersant manufactured by Big Chemie, NV (Non Volatile Organic Compound) value = 95% by mass) as a dispersant, 6.5 parts by mass, diethylene glycol ethyl methyl After mixing and stirring 73.5 parts by mass of ether, dynamic light scattering method using Zetasizer 1000 (manufactured by Malvern) with a sand grinder filled with 0.5 mm zirconia beads at a volume rate of 50%. Dispersed until the Z-average particle size measured by the method was 140 nm, and a dispersion liquid 2 having a colorant solid content of 20% by mass was prepared.

Next, 10 parts by mass of the dispersion liquid 2 prepared above, 6.0 parts by mass of H14/36 (manufactured by Wacker Chemie AG) as a vinyl chloride copolymer resin, 54 parts by mass of diethylene glycol methyl ethyl ether as a solvent, 10.0 parts by mass of diethylene glycol diethyl ether, 10.0 parts by mass of gamma-butyrolactone, and 10.0 parts by mass of propylene glycol monomethyl ether acetate were mixed, stirred and uniformly mixed, and filtered through a 1 μm mesh filter. , Ink 2 was prepared.

[Measurement of contact angle]
Next, the contact angles of the ink 2 with respect to the transfer member 1 at 25° C. and 50° C. were measured in the same manner as described above. was 68 degrees.

[Formation of inkjet image]
Using a Peltier cooling unit, an ink 2 is ejected from an inkjet recording apparatus having an inkjet recording head equipped with a piezo type inkjet nozzle onto a transfer body 1 set at 25° C. to form an image. 1 is heated to 45 ° C. (LCST temperature or higher), pressurized transfer to printing coated paper B (matte synthetic paper SV-YPM-170 paper thickness 170 μm, manufactured by Japan FDC Co., Ltd.) as a recording medium. After that, it was dried by heating at 60° C. for 15 seconds to produce a printed matter 2 .

[Preparation of printed matter 3]
Printed matter 1 was produced in the same manner, except that transfer material 1 was used, ink 1 was changed to ink 3 described below, and formation of the inkjet image was changed to the formation method described below. was made.

[Preparation of ink 3: UV curable pigment ink, no gelling agent]
20 parts by mass of Lionol Blue FG-7400-G (manufactured by Toyocolor Co., Ltd.) as a cyan pigment, 6.5 parts by mass of BYKJET-9151 (manufactured by BYK) as a dispersant, and polyethylene glycol diacrylate as a photopolymerizable compound. (NK Ester A-400 Shin-Nakamura Chemical Co., Ltd.) 73.2 parts by mass, 0.3 parts by mass of Irgastab UV10 (manufactured by BASF) as a photopolymerization inhibitor, and zirconia beads (YTZ ball 0.3 mm Nikkato) and was placed in a 100 mL plastic container and dispersed for 3 hours with a paint shaker.

Then, 10 parts by mass of dispersion liquid 3, 43.9 parts by mass of 1) NK Ester A-400 (described above) and 2) 4EO-modified pentaerythritol tetraacrylate (SR494 Sartomer Japan Co., Ltd.) as a photopolymerizable compound ), 3) 15 parts by mass of 3PO-modified trimethylolpropane triacrylate (EM2381 manufactured by Eternal Chemical Co., Ltd.), 6 parts by mass of IRGACURE819 (manufactured by BASF) as a photoinitiator, and Irgastab as a polymerization inhibitor. Ink 3 was prepared by adding 0.1 part by mass of UV10 (manufactured by BASF), stirring at 105° C. for 45 minutes, and filtering through a Teflon (registered trademark) 3 μm membrane filter manufactured by ADVANTEC.

[Measurement of contact angle]
Next, the contact angles of the ink 3 on the transfer member 1 at 25° C. and 50° C. were measured in the same manner as described above. was 82 degrees.

[Formation of inkjet image]
Using a Peltier cooling unit, an ink 3 is ejected from an inkjet recording apparatus having an inkjet recording head equipped with a piezo type inkjet nozzle onto the transfer body 1 set at 25° C. to form an image. 1 was heated to 45° C. (the LCST temperature or higher), and pressurized transfer to the coated printing paper A was performed. Thereafter, the transferred image was irradiated with 350 mJ of UV light of 395 nm in total to cure the ink to obtain a printed matter 3 .

[Preparation of printed matter 4]
A printed matter 4 was prepared in the same manner as in the preparation of the printed matter 3, except that the transfer member 1 was used and the ink 3 was changed to the ink 4 described below.

[Preparation of ink 4: UV curable pigment ink with gelling agent]
In the preparation of printed matter 3, 10 parts by mass of dispersion liquid 3 used in the preparation of ink 3, and as a photopolymerizable compound, 1) 42.9 parts by mass of NK ester A-400, 2) 4EO-modified pentaerythritol tetraacrylate 23 parts by mass of (SR494: SARTOMER), 3) 13 parts by mass of 3PO-modified trimethylolpropane triacrylate (EM2381 Eternal Chemical), 6 parts by mass of IRGACURE819 (manufactured by BASF) as a photoinitiator, Unistar as a gelling agent Add 5 parts by mass of RM-2222SL (behenyl behenate, manufactured by NOF Corporation) and 0.1 part by mass of Irgastab UV10 (manufactured by BASF) as a polymerization inhibitor, stir at 105 ° C. for 45 minutes, and then add Teflon manufactured by ADVANTEC. Ink 4 was prepared by filtration through a (registered trademark) 3 μm membrane filter.

[Measurement of contact angle]
Next, the contact angles of the ink 4 with respect to the transfer member 1 at 25° C. and 50° C. were measured in the same manner as described above. was 88 degrees.

[Formation of inkjet image]
Using a Peltier cooling unit, an ink 4 is ejected from an inkjet recording apparatus having an inkjet recording head equipped with a piezo inkjet nozzle onto the transfer body 1 at 25° C. to form an image. 1 was heated to 45° C. (above the LCST temperature and below the gelling point), and pressure transfer was performed onto coated printing paper A. Thereafter, the transferred image was irradiated with 350 mJ of UV light of 395 nm in total to cure the ink to obtain a printed matter 4 .

[Preparation of printed materials 5 to 8]
Prints 5 to 8 were produced in the same manner as in the production of prints 1 to 4, except that transfer body 2 produced by the method described below was used in place of transfer body 1.

[Preparation of Transfer Body 2]
In the production of the transfer member 1, N,N-dimethylacrylamide is used instead of N-isopropylacrylamide, which is a monomer of the thermoresponsive polymer, and the thermoresponsive polymer (poly(N,N-dimethylacrylamide ), LCST: 25° C.), and a transfer member 2 was produced in the same manner except that this was used.

[Preparation of printed materials 9 to 12]
In the production of the above prints 1 to 4, the transfer body 3 was prepared by the method described below instead of the transfer body 1, and the formation of the inkjet image was changed to the formation method described below. Thus, prints 9 to 12 were produced.

[Preparation of Transfer Body 3]
In the production of transfer member 1, N-cyclopropylacrylamide is used instead of N-isopropylacrylamide, which is a monomer of the thermosensitive polymer, and the thermoresponsive polymer (poly(N-cyclopropylacrylamide), LCST: 47° C.) was prepared, and transfer member 3 was produced in the same manner except that this was used.

[Formation of inkjet image]
Prints 9 to 12 were produced in the same manner as in the production of Prints 1 to 4, except that the heating temperature of the transfer member 3 by the Peltier heating unit was changed to 55.degree.

[Preparation of printed matter 13]
A printed matter 13 was prepared in the same manner as in the production of the printed matter 4 except that the transfer member 4 produced by the method described below was used in place of the transfer member 1 .

[Preparation of Transfer Body 4]
In the production of transfer member 1, N-tert-butylacrylamide is used in place of N-isopropylacrylamide, which is a monomer of the thermosensitive polymer, and the thermoresponsive polymer (poly(N-tert-butylacrylamide ), LCST: 40° C.), and transfer member 4 was produced in the same manner except that this was used.

[Preparation of printed matter 14]
In the production of the printed matter 4, instead of the transfer body 1, a transfer body 5 manufactured by the method described below was used, and the heating temperature of the transfer body 5 by the Peltier heating unit during the formation of the inkjet image was changed to 50°C. A printed matter 14 was produced in the same manner except that

[Preparation of Transfer Body 5]
In the production of transfer member 1, N-ethylacrylamide is used instead of N-isopropylacrylamide, which is a monomer of the thermosensitive polymer, and the thermoresponsive polymer (poly(N-ethylacrylamide), LCST: 43° C.) was prepared, and a transfer member 5 was produced in the same manner except that this was used.

[Preparation of printed matter 15]
In the production of the printed matter 4, instead of the transfer body 1, a transfer body 6 manufactured by the method described below was used, and the heating temperature of the transfer body 6 by the Peltier heating unit during the formation of the inkjet image was changed to 60°C. A printed matter 15 was produced in the same manner except that

[Preparation of Transfer Body 6]
In the production of transfer member 1, 1-acryloylpyrrolidine is used instead of N-isopropylacrylamide, which is a monomer of the thermosensitive polymer, and the thermoresponsive polymer (poly(1-acryloylpyrrolidine), LCST: 55° C.) was prepared, and a transfer body 6 was produced in the same manner except that this was used.

[Preparation of printed matter 16]
A printed matter 16 was prepared in the same manner as in the production of the printed matter 4 except that a transfer member 7 produced by the method described below was used in place of the transfer member 1 .

[Preparation of Transfer Body 7]
In the production of transfer member 1, instead of N-isopropylacrylamide, which is a monomer of the thermosensitive polymer, ethyl vinyl ether is used, and the thermosensitive polymer (poly(ethyl vinyl ether), LCST: 22° C.) is used. A transfer member 7 was produced in the same manner as above, except that this was prepared.

[Preparation of printed matter 17-19]
Prints 17 to 19 were produced in the same manner as in the production of printed matter 4, except that the heating temperature of the transfer member 1 by the Peltier heating unit during the formation of the inkjet image was changed to 40° C., 50° C., and 60° C., respectively. bottom.

[Preparation of printed materials 20 to 23]
Prints 20 to 23 were produced in the same manner as in the production of prints 1 to 4, except that the transfer member 1 was replaced with a photoresponsive transfer member 8 produced by the method described below.

[Preparation of Transfer Body 8]
A polyimide film (thickness: 40 μm) was used as the transfer substrate, and corona discharge (corona output intensity: 2.0 kW, line speed: 18 m/min) was applied to the transfer substrate surface to activate the transfer substrate surface. After that, the sample was immersed in 4-hexyl-2methoxy-4'-bromomethylstilbene and 1,2-dichloroethane, concentrated sulfuric acid was added dropwise, and the sample was allowed to stand at 60°C for 12 hours. After that, the polyimide film was spray-washed with dichloromethane and dried at 55° C. for 30 minutes to obtain a transfer member 8 . The 4-hexyl-2methoxy-4'-bromomethylstilbene contained in the transfer body 8 is a material that becomes more hydrophilic when irradiated with ultraviolet light and more hydrophobic when heated.

[Formation of inkjet image]
As shown in FIG. 2, the transfer body 8 was heated to 25° C. using a Peltier cooling unit and irradiated with ultraviolet rays in a preliminary light irradiation section (51) to make the surface hydrophilic, and then a piezoelectric inkjet nozzle was provided. After inks 1 to 4 are ejected from an inkjet recording apparatus having an inkjet recording head to form an image, the transfer body 8 is heated to 45° C. by a Peltier heating unit, and pressure transfer is performed onto the coated printing paper A. gone. In the level using the inks 3 and 4, the transferred image was irradiated with UV light of 395 nm for a total of 350 mJ, and the inks were cured to obtain prints 22 and 23 .

[Preparation of printed materials 24 to 27]
Prints 24 to 27 were produced in the same manner as in the production of prints 1 to 4, except that transfer body 9 produced by the method described below was used in place of transfer body 1.

[Preparation of Transfer Body 9]
A polyimide film (thickness: 40 μm) was used as the transfer substrate, and corona discharge (corona output intensity: 2.0 kW, line speed: 18 m/min) was applied to the transfer substrate surface to activate the transfer substrate surface. After that, a 5.0% by mass ethanol solution of aminopropyltriethoxysilane was sprayed, followed by spraying with a 3.0% aqueous ammonia solution, followed by drying at 80° C. for 1 hour to obtain a thermosensitive polymer. A transfer body 9 composed of a single polyimide film was produced.

[Preparation of printed materials 28 to 31]
Prints 28 to 31 were produced in the same manner as in the production of prints 1 to 4, except that transfer body 10 produced by the method described below was used in place of transfer body 1.

[Production of Transfer Body 10]
A polyimide film (thickness: 40 μm) was used as the transfer substrate, and corona discharge (corona output intensity: 2.0 kW, line speed: 18 m/min) was applied to the transfer substrate surface to activate the transfer substrate surface. After that, a 5.0% by mass ethanol solution of aminopropyltriethoxysilane was sprayed, followed by a 3.0% aqueous ammonia solution, followed by drying at 80° C. for 1 hour.

The polyimide film was then immersed in a dichloromethane solution of 2-bromoisobutyryl bromide and triethylamine and allowed to stand at 25° C. for 12 hours. After that, the polyimide film was spray-washed with dichloromethane and dried. The resulting polyimide film was immersed in a methanol/water solution containing 2-ethylhexyl vinyl ether, N,N,N',N″,N″-pentamethyldiethylenetriamine, and copper(I) chloride/copper(II) bromide. and allowed to stand at 25° C. for 5 hours. After the obtained polyimide film was spray-washed with methanol, it was dried at 55° C. for 30 minutes to prepare a transfer member 10 . The transfer member 10 does not have the characteristic of changing the contact angle with thermal stimulation.

[Preparation of printed materials 32 to 35]
Prints 32 to 35 were produced in the same manner as in the production of prints 1 to 4, except that transfer body 11 produced by the method described below was used in place of transfer body 1.

[Preparation of Transfer Body 11]
A polyimide film (thickness: 40 μm) was used as the transfer substrate, and corona discharge (corona output intensity: 2.0 kW, line speed: 18 m/min) was applied to the transfer substrate surface to activate the transfer substrate surface. After that, a 5.0% by mass ethanol solution of aminopropyltriethoxysilane was sprayed, followed by a 3.0% aqueous ammonia solution, followed by drying at 80° C. for 1 hour.

The polyimide film was then immersed in a dichloromethane solution of 2-bromoisobutyryl bromide and triethylamine and allowed to stand at 25° C. for 12 hours. After that, the polyimide film was spray-washed with dichloromethane and dried. The resulting polyimide film was immersed in a methanol/water solution containing trimethyl(vinyloxy)silane, N,N,N',N″,N″-pentamethyldiethylenetriamine, and copper(I) chloride/copper(II) bromide. It was immersed and allowed to stand at 25° C. for 5 hours. The resulting polyimide film was spray-washed with methanol, dried with air, immersed in 0.1 N hydrochloric acid, and allowed to stand at 25° C. for 15 minutes. The resulting polyimide film was spray-washed with methanol and then dried at 55° C. for 30 minutes to prepare a transfer member 11 . The transfer member 11 does not have the property of changing the contact angle due to thermal stimulation.

《Evaluation of printed materials》
[Measurement of contact angle change due to external stimulation]
(Measurement of contact angle for thermal stimulation on printed matter 1-19, 24-35)
In each of the above prints, the contact angle at room temperature was measured at 25°C for the levels using ink 1 and ink 2, and the contact angle at 50°C when heated with a thermal stimulus was measured. Shown in Table I.

In addition, in each of the above printed materials, the contact angle at room temperature was measured at 25°C for the level using ink 3 and ink 4, and the contact angle at 50°C when heated with thermal stimulation was measured. Results are shown in Table I. In addition, in the printed matter 15 using the ink 4 and the transfer body 6, the contact angle during heating was measured at 60.degree.

As described above, the contact angle was measured using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., trade name DropMaster DM100) by dropping 1 μL of the ink and measuring the contact angle 1 minute later. Measurements were taken at arbitrary 10 points on each transfer member, and the average value was obtained.

(Measurement of contact angle to light stimulus on printed matter 20-23)
For each of the above printed materials 20 to 23, the contact angle was measured at 25°C after being irradiated with ultraviolet light as a light stimulus, and the contact angle during heating with thermal stimulation was measured at 50°C. I. In Table I, the contact angle (25 ° C.) after irradiation with ultraviolet light as a light stimulus is described in the "contact angle at room temperature" column, and the contact angle at the time of heating (50 ° C.) with thermal stimulation is described in the "heating contact angle” column.

[Evaluation of Transferability]
The mass of each ink ejected from the inkjet head was calculated from the sum of the mass increase of the recording medium and the mass of the ink remaining on the transfer body, and the transfer rate was obtained from the following formula, and the transferability was evaluated according to the following criteria. .

Transfer rate (%) = (mass of ink transferred to recording medium/total mass of ink ejected onto transfer body) x 100
A: The transfer rate is 95% or more B: The transfer rate is 90% or more and less than 95% B: The transfer rate is 80% or more and less than 90% X: The transfer rate is less than 80%.

[Evaluation of image quality/dot diameter]
The dot diameter and shape of the ink jet image formed on the recording medium by the above method under the condition that the dot diameter becomes 60 μm was observed with an optical microscope, and the image quality/dot was evaluated according to the following evaluation criteria.

A: The formed dot diameter is within the range of 56 to 64 μm, and no unevenness or edge blur is observed in the formed dots. ○: The formed dot diameter is within the range of 51 to 55 μm or 65 to 70 μm , and no unevenness or edge blurring is observed in the formed dots. △: the diameter of the formed dots is in the range of 41 to 50 µm or 71 to 80 µm, and no unevenness or edge blurring is observed in the formed dots. The dot diameter is less than 41 μm or 81 μm or more, or unevenness or edge blurring is observed in the formed dots.

Table I shows the results obtained above.

As is clear from the results shown in Table I, the printed matter formed by the inkjet image forming method using the transfer member carrying the material that changes the contact angle with an external stimulus defined in the present invention is superior to the comparative example. , the ink-jet image formed on the transfer member is excellent in transferability to the recording medium, and the formed image is excellent in dot diameter reproducibility and shape. In particular, by using a transfer body having a heat-sensitive polymer whose contact angle changes due to heat stimulation as an external stimulus, and an actinic radiation-curable ink, especially an actinic radiation-curable ink containing a gelling agent, as an ink, It turns out that the said effect is exhibited more.

REFERENCE SIGNS LIST 1 transfer body 2 transfer substrate 3A thermal response layer having small contact angle surface 3B thermal response layer having large contact angle surface 4 ink droplet 5 recording medium 8 inkjet image forming apparatus 10 head carriage 11Y, 11C, 11M, 11K inkjet Head 20 Transfer Unit 22, 23, 24 Belt Support Roller 30 Recording Medium Conveying Roller 50 Actinic Ray Irradiation Unit 51 Preliminary Light Irradiation Unit C Cooling Unit CL Cleaning Unit H Heating Unit

Claims (7)

A transfer member for an inkjet image forming apparatus using inkjet ink,
A material whose contact angle changes with an external stimulus is carried on the transfer substrate,
the external stimulus is a thermal stimulus;
The material whose contact angle changes due to an external stimulus is a thermosensitive polymer and has a lower critical solution temperature (LCST), and the LCST is in the range of 22 to 47 ° C.,
When using an inkjet ink having a contact angle with respect to the material supported on the transfer substrate at 25° C. (room temperature) in the range of 38 to 82 degrees, the ink is supported on the transfer substrate at 50° C. the contact angle to the material being carried on the transfer substrate is higher than the contact angle to the material being carried on the transfer substrate at 25° C. within the range of 3 to 27 degrees
A transfer body characterized by: 2. The transfer member according to claim 1, wherein the transfer member is applied to an image forming method using a water-based dye ink or an organic solvent-based dye ink as the inkjet ink. 2. The transfer member according to claim 1 , which is applied to an image forming method using an actinic radiation-curable inkjet ink that is cured by actinic rays as the inkjet ink. The actinic radiation curable inkjet ink contains a gelling agent, has a gelling temperature equal to or higher than the LCST of the heat-sensitive responsive polymer contained in the transfer body, and assumes a gel state at a gelling temperature or lower. The transfer member according to claim 3 . An inkjet image forming apparatus comprising the transfer member according to any one of claims 1 to 4 . An inkjet image forming method using a transfer body carrying a material whose contact angle changes with an external stimulus on a transfer base material,
Using an actinic radiation curable inkjet ink as the inkjet ink,
cooling the transfer body to change the degree of contact angle of the actinic radiation curable inkjet ink with respect to ink droplets;
A step of landing ink droplets of the actinic radiation curable inkjet ink on the transfer body;
heating the transfer body to change the degree of contact angle of the ink droplets on the surface of the transfer body;
transferring the ink droplets onto a recording medium;
a step of irradiating the ink droplets transferred onto the recording medium with an actinic ray to form a cured film constituting an inkjet image;
a cleaning step of removing the inkjet image remaining on the transfer body;
An inkjet image forming method, comprising: An inkjet image forming method using the transfer member according to claim 1 or 2 ,
As the inkjet ink, using a water-based dye ink or an organic solvent-based dye ink,
cooling the transfer body to change the degree of contact angle of the inkjet ink with respect to ink droplets;
A step of landing ink droplets of the inkjet ink on the transfer body;
heating the transfer body to change the degree of contact angle of the ink droplets on the surface of the transfer body;
transferring the ink droplets onto a recording medium;
a step of applying heat to the ink droplets transferred onto the recording medium to form a cured film constituting an inkjet image;
a cleaning step of removing the inkjet image remaining on the transfer body;
An inkjet image forming method, comprising:

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