JP2020172593A - Intermediate transfer body, image forming apparatus and image forming method - Google Patents

Abstract

To provide an intermediate transfer body which has high followability to unevenness of a recording medium, and prevents penetration of a liquid composition such as ink.SOLUTION: The present invention relates to an intermediate transfer body that has a base material layer, an elastic layer and a surface layer, to which a liquid composition is imparted, and that transfers the imparted liquid composition onto a recording medium, in which the surface layer has 90 pts.mass or more and 99 pts.mass or less of a binder resin having a tensile elastic modulus of 0.1 MPa or more and 20 MPa or less, and 1 pt.mass or more and 10 pts.mass or less of a filler having an average value of the maximum particle diameter of 10 nm or more and 1,000 nm or less (total mass of binder resin and filler is 100 pts.mass.).SELECTED DRAWING: Figure 1

Description

The present invention relates to an intermediate transfer member, an image forming apparatus and an image forming method.

Since the inkjet method can produce an image easily and inexpensively, it is applied to various printing fields including special printing such as various printing, marking, fine line formation, and color filter. In particular, the inkjet method is particularly suitable for applications such as forming various images little by little because digital printing is possible without using a plate.

In the inkjet method, there is known an image forming method in which an intermediate image is formed on the surface of an intermediate transfer body and then the intermediate image is transferred to a recording medium.

As an intermediate transfer body used in such an image forming method, for example, Patent Document 1 describes a needle-shaped filler in a direction perpendicular to the direction of pressure applied when the intermediate transfer body is pressure-bonded to a recording medium and a recording medium. An intermediate transcript is described that is oriented and included in the transport direction of. According to Patent Document 1, the intermediate transfer body is deformed in the direction perpendicular to the direction of pressure applied during pressure bonding to the recording medium (compressive elastic modulus), and in the direction of transport of the recording medium. Since the (compressive elastic modulus) becomes small, it is said to be superior in terms of transferability to a wide variety of recording media and quality of transferred images. Further, Patent Document 1 describes that it is effective to lower the compressive elastic modulus in order to deform the intermediate transfer body according to the surface shape of the recording medium type having a large surface roughness.

Further, Patent Document 2 describes that the outer peripheral surface of the belt body having a tensile elastic modulus of 1 to 10 MPa has a film thickness of 2 to 20 μm, a tensile elastic modulus of 2 to 140 MPa, and a carbon number in a dynamic wettability test. Described are conductive belts for electrophotographic devices provided with a belt surface layer having a receding contact angle of 9 to 14 with respect to unsaturated hydrocarbon solvents of 10 ° or more. According to Patent Document 2, by lowering the tensile elastic modulus of the surface layer, the paper compatibility with rough paper is improved, and by increasing the receding contact angle, the releasability of the oil-based component-containing toner is high. It is stated that it will be.

Japanese Unexamined Patent Publication No. 2011-218977 Japanese Unexamined Patent Publication No. 2005-31165

As described in Patent Document 1 and Patent Document 2, a recording medium having a large surface roughness is obtained by lowering the compressive elastic modulus of the intermediate transfer medium and improving the unevenness followability of the intermediate transfer medium to a wide variety of recording media. It is expected that the transferability of the image from the intermediate transfer body to the image can be enhanced. However, according to the findings of the present inventors, if the elastic modulus of the intermediate transfer body is lowered in an attempt to improve the transferability to a recording medium having larger irregularities, the penetrability of the ink into the intermediate transfer body becomes excessive. In some cases, it increased and the quality of the obtained image deteriorated.

The present invention has been made based on the above findings, and is an intermediate transfer body having high followability to irregularities of a recording medium and having difficulty in penetrating a liquid composition such as ink, and an image forming apparatus having the intermediate transfer body. , And to provide an image forming method using the intermediate transfer material.

The above problem is solved by an intermediate transfer body which is provided with a liquid composition having a base material layer, an elastic layer and a surface layer, and for transferring the given liquid composition to a recording medium. The surface layer is composed of a binder resin having a tensile elastic modulus of 0.1 MPa or more and 20 MPa or less and 1 part by mass or more and 10 parts by mass or less, and an average maximum particle size of 10 nm or more and 1000 nm. It has the following filler (the total mass of the binder resin and the filler is 100 parts by mass).

Further, the above-mentioned problems include the intermediate transfer body, a composition-imparting unit for imparting a liquid composition to the intermediate transfer body, and a transfer unit for transferring the liquid composition applied to the intermediate transfer body to a recording medium. It is solved by an image forming apparatus having.

Further, the above-mentioned problem is solved by an image forming method including a step of applying a liquid composition to the intermediate transfer body and a step of transferring the liquid composition applied to the intermediate transfer body to a recording medium. To.

INDUSTRIAL APPLICABILITY According to the present invention, an intermediate transfer body having high followability to unevenness of a recording medium and difficult for a liquid composition such as ink to penetrate, an image forming apparatus having the intermediate transfer body, and an image forming method using the intermediate transfer body. Is provided.

FIG. 1 is a schematic view showing a partial cross section of an intermediate transfer member according to the first embodiment of the present invention. FIG. 2 is a schematic diagram showing an exemplary configuration of an image forming apparatus according to a second embodiment of the present invention. FIG. 3 is a flowchart of an image forming method according to a third embodiment of the present invention.

1. 1. Intermediate Transfer Body The first embodiment of the present invention relates to an intermediate transfer body for an inkjet having a base material layer, an elastic layer and a surface layer. The intermediate transfer body is suitably used for image formation with a liquid composition such as an inkjet ink.

FIG. 1 is a schematic view showing a partial cross section of the intermediate transfer body 100 according to the present embodiment. The intermediate transfer body 100 has a base material layer 110, an elastic layer 120 and a surface layer 130 which is the outermost layer, which are laminated in this order on the base material layer 110.

1-1. Base material layer The base material layer 110 may be formed from a resin material or a metal material as long as it is a base material contained in the intermediate transfer body used for image formation by the liquid composition. Examples of the resin material of the base material layer 110 include aromatic polyimide (PI), aromatic polyamideimide (PAI), polyvinylidene fluoride (PPS), aromatic polyetheretherketone (PEEK), aromatic polycarbonate (PC), and the like. And resins having structural units containing a benzene ring such as aromatic polyetherketone (PEK), polyvinylidene fluoride (PVDF), and mixtures or copolymers thereof and the like are included. Examples of the metal material of the substrate layer 110 include metals such as steel, aluminum and stainless steel.

The thickness of the base material layer 110 may be such that it can impart sufficient strength to the intermediate transfer material 100, and can be, for example, 30 μm or more and 500 μm or less.

1-2. Elastic layer The elastic layer 120 may be any elastic layer contained in the intermediate transfer body used for image formation by the liquid composition.

The elastic layer 120 can be formed of a rubber component that can be deformed by following the unevenness of the surface of the recording medium on which the image is transferred. Examples of materials for the elastic layer 120 include rubbers such as silicone rubber (SR), chloroprene rubber (CR), nitrile rubber (NBR) and epichlorohydrin rubber (ECO), elastomers, elastic resins and the like.

The elastic layer 120 preferably has a rubber hardness of 8 ° or more and 40 ° or less. When the rubber hardness is 8 ° or more, the strength of the elastic layer can be sufficiently increased, and the formation and transfer of the intermediate image can be performed better. When the rubber hardness is 40 ° or less, the surface of the intermediate transfer body (the outermost surface of the surface layer) is made more easily deformed by following the unevenness of the surface of the recording medium, so that the recording medium having a large surface roughness can be obtained. The transferability of the image can be further improved. From the above viewpoint, the rubber hardness of the elastic layer 120 is more preferably 8 ° or more and 20 ° or less, and further preferably 9 ° or more and 16 ° or less.

The rubber hardness of the elastic layer 120 can be a value measured using a type A durometer according to JIS K 6253-3 (2012).

From the viewpoint of lowering the rubber hardness of the elastic layer 120 (for example, 8 ° or more and 20 ° or less), the elastic layer 120 preferably contains softer rubber, for example, silicone rubber. The content of the silicone rubber is preferably 50 parts by mass or more and 100 parts by mass or less, preferably 70 parts by mass or more and 100 parts by mass or less, when the total mass of the rubber components contained in the elastic layer 120 is 100 parts by mass. It is more preferably 80 parts by mass or more and 100 parts by mass or less.

Further, the elastic layer 120 preferably has a thickness of 200 μm or more and 1000 μm or less. When the thickness is 200 μm or more, the strength of the elastic layer 120 can be sufficiently increased, and the formation and transfer of the intermediate image can be performed better. When the thickness is 1000 μm or less, the surface of the intermediate transfer body (the outermost surface of the surface layer) is made more easily deformed by following the unevenness of the surface of the recording medium, and the image on the recording medium having a large surface roughness is easily deformed. The transferability can be further enhanced. From the above viewpoint, the thickness of the elastic layer 120 is more preferably 200 μm or more and 500 μm or less, and further preferably 300 μm or more and 500 μm or less.

The thickness of the elastic layer 120 can be a value measured using a known film thickness meter.

1-3. Surface layer The surface layer 130 is a layer constituting the outermost surface of the intermediate transfer member 100.

In the present embodiment, the surface layer 130 is composed of a binder resin having a tensile elastic modulus of 0.1 MPa or more and 20 MPa or less and 1 part by mass or more and 10 parts by mass or less, which is the average of the maximum particle diameters. A filler having a value of 10 nm or more and 1000 nm or less is included.

The binder resin has a relatively small tensile elastic modulus of 0.1 MPa or more and 20 MPa or less, and has high flexibility. Therefore, the surface layer 130 containing the binder resin is easily deformed together with the elastic layer 120 following the unevenness of the surface of the recording medium, and the transferability of the image to the recording medium having a large surface roughness can be further improved. From the above viewpoint, the tensile elastic modulus of the binder resin is preferably 2 MPa or more and 20 MPa or less, and more preferably 5 MPa or more and 20 MPa or less.

The tensile elastic modulus of the binder resin is determined by pulling a dumbbell-shaped No. 1 (JIS K 6251 (2017)) test piece having a thickness of 30 to 80 μm at a tensile speed of 200 mm / min, and the stress at the time of tension and its tension. It can be obtained by measuring the strain at the time. At this time, the value obtained by dividing the difference in stress between the point where the strain is 0.05 (%) and the point where the strain is 0.25 (%) by the difference in strain at the above two points is the above binder. It may be the tensile elastic modulus of the resin.

The binder resin may be any resin that satisfies the above-mentioned tensile elastic modulus. For example, a polymer obtained by copolymerizing a perfluorovinyl monomer or a trifluorovinyl monomer and a vinyl ether monomer and cured with an isocyanate-based curing agent such as alkyl isocyanate is used as the binder resin. preferable.

When the amount of the structure derived from all the monomers used in the synthesis is 100 mol%, the above copolymer contains 30 mol% or more and 70 mol% or less of the structure derived from the perfluorovinyl monomer or the trifluorovinyl monomer. It is preferably contained in an amount of 50 mol% or more and 70 mol% or less. When the structure derived from the perfluorovinyl monomer or the trifluorovinyl monomer is 30 mol% or more, a sufficient amount of cross-linking points are formed in the copolymer, and the durability of the surface layer 130 can be further enhanced. it can. When the structure derived from the perfluorovinyl monomer or the trifluorovinyl monomer is 70 mol% or less, the amount of cross-linking points in the copolymer does not become excessive, and the flexibility of the surface layer 130 can be further enhanced. it can.

Further, in the polymer, when the total mass of the copolymer is 100 parts by mass, the amount of the isocyanate-based curing agent is preferably 10 parts by mass or more and 20 parts by mass or less, and 10 parts by mass or more and 15 parts by mass. It is more preferable that the content is less than or equal to a portion.

Since the binder resin has a small tensile elastic modulus, the gap distance between the molecular chains is relatively large. Therefore, the binder resin makes it easy for a liquid composition having a relatively small amount of liquid, which is ejected from an inkjet head and lands on the surface layer, to pass through the molecular gaps thereof, and the liquid composition penetrates into the surface layer 130. Easy to make.

On the other hand, the surface layer 130 contains the filler having an average maximum particle size of 10 nm or more and 1000 nm or less. A filler having an average maximum particle size in the above range physically fills the gaps between the molecular chains of the binder resin, making it difficult for the liquid composition to penetrate into the surface layer 130. When the average value of the maximum particle size is 10 nm or more, the penetration of the liquid composition can be effectively suppressed. When the average value of the maximum particle diameter is 1000 nm or less, the smoothness of the outermost surface of the surface layer 130 can be maintained, and the quality (particularly glossiness) of the transferred image can be maintained. From the above viewpoint, the average value of the maximum particle size of the filler is preferably 30 nm or more and 500 nm or less, and more preferably 50 nm or more and 300 nm or less.

The average value of the maximum particle size of the filler can be obtained by cutting out a stripped section from the surface layer 130 using a microtome or the like and imaging a transmission image of the stripped section using a transmission electron microscope (TEM). .. At this time, the transmitted image is imaged in a field of view in which about 100 of the fillers are reflected in the image, and the average value of the lengths of the long sides measured for 50 fillers selected from the obtained transmitted images is calculated. , The average value of the maximum particle diameters of the above fillers may be used.

The filler may be any known filler used for changing the physical properties (strength, heat resistance, various resistances, etc.) of the resin, such as calcium carbonate, mica, talc, silica and glass. Of these, calcium carbonate, mica, talc and silica are preferred, with silica being more preferred.

The filler may be composite particles in which a plurality of materials are compounded to form a single particle, but it is preferably a single material particle composed of a single material.

The shape of the filler is not particularly limited, and it may be spherical, rod-shaped, or flat-plate. However, from the viewpoint of sufficiently suppressing the penetration of the liquid composition even with a small amount of filler, a shape having a high aspect ratio such as a flat plate is preferable. The aspect ratio of the filler is preferably 5 or more and 20 or less, and more preferably 10 or more and 20 or less.

The aspect ratio of the filler is the average value of the length of the long side and the length of the short side measured for 50 fillers selected from the transmitted images obtained in the same manner as the measurement of the average value of the maximum particle size. Good.

The content of the binder resin and the filler in the surface layer 130 is such that the content of the binder resin is 90 parts by mass or more and 99 parts by mass or less when the total mass of the binder resin and the filler is 100 parts by mass, and the content of the filler is Is 1 part by mass or more and 10 parts by mass or less. With the above content, the flexibility of the surface layer 130 (the ability to follow the unevenness of the surface of the recording medium) can be increased at the same time while sufficiently suppressing the penetration of the liquid composition. From the above viewpoint, the content of the binder resin and the filler is preferably such that the content of the binder resin is 92 parts by mass or more and 99 parts by mass or less, and the content of the filler is 1 part by mass or more and 8 parts by mass or less. It is more preferable that the binder resin content is 92 parts by mass or more and 96 parts by mass or less, and the filler content is 4 parts by mass or more and 8 parts by mass or less.

As the material of the surface layer 130, a metal such as stainless steel, a fluororesin having a high fluorine content (Teflon (“Teflon” is a registered trademark of Zakemers Company)), and a non-permeable resin such as a silicone resin are used. However, it is possible to suppress the permeation of the liquid composition into the surface layer 130. However, these materials have poor flexibility and cannot improve the ability to follow the irregularities on the surface of the recording medium.

The surface layer 130 may further contain a compatibilizer in addition to the binder resin and filler. The compatibilizer enhances the adhesion between the binder resin and the filler, more sufficiently suppresses the penetration of the liquid composition, and the flexibility of the surface layer 130 (following the unevenness of the surface of the recording medium). ) Can also be increased.

Examples of the compatibilizer include acid-modified polyethylene, acid-modified propylene, and acid-modified ethylene-butylene-styrene block copolymers, all of which have been graft-modified with maleic anhydride or the like.

The content of the compatibilizer in the surface layer 130 is preferably 0.1 part by mass or more and 3 parts by mass or less, preferably 0.1 part by mass or more, when the total mass of the binder resin and the filler is 100 parts by mass. It is more preferably 2 parts by mass or less, and further preferably 0.1 part by mass or more and 1 part by mass or less.

The thickness of the surface layer 130 is preferably 1 μm or more and 30 μm or less. When the thickness is 1 μm or more, the strength of the surface layer 130 can be sufficiently increased, and the formation and transfer of the intermediate image can be performed better. When the thickness is 30 μm or less, the outermost surface of the surface layer can be more easily deformed by following the unevenness of the surface of the recording medium, and the transferability of the image to the recording medium having a large surface roughness can be further improved. it can. From the above viewpoint, the thickness of the surface layer 130 is more preferably 1 μm or more and 20 μm or less, and further preferably 2 μm or more and 20 μm or less.

The surface layer 130 preferably has a pure water contact angle of 60 ° or less. When the contact angle is 60 ° or less, external foreign matter contamination becomes remarkable. From the above viewpoint, the contact angle is preferably 40 ° or more and 60 ° or less, and the contact angle is more preferably 45 ° or more and 60 ° or less.

The contact angle can be the average value of the contact angles measured four times by the θ / 2 method by the sessile drop method.

The intermediate transfer body is used in a so-called intermediate transfer method image forming method in which an intermediate image is formed on the intermediate transfer body using a liquid composition and the formed intermediate image is transferred from the intermediate transfer body to a recording medium. Can be done. The method for forming the intermediate image is not particularly limited, and known methods such as spray coating, immersion method, screen printing, gravure printing, offset printing, and inkjet method can be used, but dots due to droplets of the inkjet ink are aggregated. At the time of image formation by the inkjet method for forming the image, the effect of suppressing the penetration of the liquid composition in the intermediate transfer material is remarkably exhibited.

2. Image Forming Device A second embodiment of the present invention relates to an image forming device having an intermediate transfer member according to the first embodiment described above.

FIG. 2 is a schematic view showing an exemplary configuration of an image forming apparatus 200 according to the present embodiment. The image forming apparatus 200 is intermediate between the transport path 210 that conveys the recording medium 300 and the intermediate transfer body 100 according to the first embodiment, which is arranged so as to face the surface of the transport path 210 to which the recording medium 300 is conveyed. The composition-imparting portion 220, which applies an active ray-curable liquid composition to the surface of the transfer body 100 to form an intermediate image, and the active ray-curable liquid by irradiating the surface of the intermediate transfer body with active rays. It has a first irradiation unit 230 that thickens the composition, and a transfer unit 240 that transfers an intermediate image containing the thickened active ray-curable liquid composition to a recording medium. The image forming apparatus 200 further cures the support rollers 252, 254, and 256 on which the intermediate transfer body 100 having the shape of an endless belt is stretched, and the active ray-curable liquid composition constituting the intermediate image (main curing). The second irradiation unit 260 that irradiates the surface of the transport path 210 with the active rays for causing the active rays, and the active ray-curable liquid composition that remains on the surface of the intermediate transfer body 100 without being transferred to the recording medium 300. It has a cleaning unit 270 for removing from the surface of the intermediate transfer body 100.

The active ray means an energy ray having an action of polymerizing and cross-linking a photopolymerizable compound contained in the active ray-curable liquid composition to cure the active ray-curable liquid composition. Examples of active rays include ultraviolet rays, electron beams, α rays, γ rays and X-rays. From the viewpoint of safety and the ability to generate the above-mentioned polymerization and cross-linking even with a lower amount of energy, the active ray is preferably ultraviolet rays or electron beams.

The active ray-curable liquid composition means a liquid composition that is cured by irradiation with active rays. Examples of the active ray-curable liquid composition include known active ray-curable inks, particularly known active ray-curable inkjet inks.

The transport path 210 is composed of, for example, a metal drum, and transports a recording medium 300 on which an intermediate image is transferred. The transport path 210 is arranged in contact with a part of the surface of the intermediate transfer body 100, and the transfer nip is formed by pressurizing the contacting surface of the intermediate transfer body 100 by the support roller 256. The transport path 210 may have a claw (not shown) for fixing the tip of the recording medium 300. The transport path 210 conveys the recording medium 300 to the transfer nip by fixing the tip of the recording medium 300 to the claw and rotating the recording medium 300 in the counterclockwise direction in FIG.

The intermediate transfer body 100 is an intermediate transfer body according to the first embodiment described above. The intermediate transfer body 100 is stretched by the support rollers 252, 254 and 256, and the intermediate image formed on the surface of the intermediate transfer body 100 by the composition imparting unit 220 is conveyed to the transfer unit 240.

In the present embodiment, the composition-imparting unit 220 is an ink-applying unit that forms an intermediate image by an inkjet method, and is an active line of each color of Y (yellow), M (magenta), C (cyan), and K (black), respectively. It has inkjet heads 220Y, 220M, 220C and 220K that eject a curable liquid composition (inkjet ink) from a nozzle and land on the surface of the intermediate transfer member 100. In the inkjet heads 220Y, 220M, 220C and 220K, the active ray-curable liquid composition (ink) of each color is landed on the surface of the intermediate transfer member 100 at a position corresponding to the image to be formed, and the intermediate is intermediate. Form an image.

The first irradiation unit 230 irradiates the intermediate transfer body 100 with active rays while the intermediate image formed by the composition-imparting unit 220 is conveyed to the transfer unit 240. The irradiated active rays are incident on the active ray-curable liquid composition constituting the intermediate image, and the photopolymerizable compound contained in the active ray-curable liquid composition is partially polymerized and crosslinked. The first irradiation unit 230 changes the diffusion coefficient of the active ray-curable liquid composition thereby more effectively suppressing the penetration of the liquid composition.

The amount of active rays irradiated to the intermediate image by the first irradiation unit 230 is such that the active ray-curable liquid composition constituting the intermediate image can maintain sufficient wettability with respect to the recording medium at the time of transfer to the recording medium. It should be. For example, the amount of active rays irradiated to the intermediate image is such that the viscosity of the intermediate image is 5 × 10 ⁶ mPa · s or more and 2 × 10 ⁸ mPa · s or less, preferably 1 × 10 ⁷ mPa · s or more and 1 × 10 ⁸ mPa. -It is preferable that the control is performed so as to be s or less.

Further, from the viewpoint of suppressing the permeation of the liquid composition into the inside of the surface layer 130 before the first irradiation unit 230 irradiates the intermediate image with the active rays, the first irradiation unit 230 is applied after the application by the composition application unit 220. The interval until the irradiation of the active rays by the irradiation unit 230 is preferably shorter, for example, 10 ms or more and 10 seconds or less, and preferably 10 ms or more and 5 seconds or less.

The transfer unit 240 is a portion including a transfer nip in which the intermediate transfer body 100 and the transfer path 210 are closest to each other, and the intermediate transfer body 100 is urged in the direction of the transfer path 210 by the support roller 256 to be intermediate. The surface of the transport path 210 in contact with the transfer body 100 is pressurized. An intermediate image containing an active ray-curable liquid composition thickened by the first irradiation unit 230, which has been formed on the surface of the intermediate transfer body 100 and conveyed, and an intermediate image arranged on the surface of the transfer path 210 and conveyed. The recording medium 300 has been brought into contact with the transfer nip, and is transferred to the recording medium by being pressurized from the intermediate transfer body 100 to the transport path 210 side via the support roller 256.

The second irradiation unit 260 is arranged on the downstream side of the transfer unit 240 in the transport direction of the recording medium 300 by the transport path 210, and irradiates the active rays toward the surface of the transport path 210. As a result, the second irradiation unit 260 irradiates the active ray-curable liquid composition constituting the intermediate image transferred to the recording medium 300 with active rays, and the active ray-curable liquid composition constituting the intermediate image. The object is cured (main curing). As a result, a target image is formed on the surface of the recording medium 300.

The cleaning unit 270 is a cleaning roller such as a web roller or a sponge roller, and comes into contact with the surface of the intermediate transfer body 100 on the downstream side of the transfer unit 240. The cleaning unit 270 removes the residual liquid composition (residual coating material) remaining on the surface of the intermediate transfer body 100 without being transferred to the recording medium 300 by the transfer unit 240 by driving and rotating the cleaning roller.

In the above description, an intermediate image is formed on the surface of the intermediate transfer body by an inkjet method, but the method for forming the intermediate image is not particularly limited, and spray coating, immersion method, screen printing, gravure printing, and offset printing are used. A known method such as can be used. Among these methods, the effect of suppressing the penetration of the liquid composition by the intermediate transfer material is remarkably exhibited at the time of image formation by the inkjet method for forming an image in which dots formed by droplets of the inkjet ink are aggregated.

Further, in the above description, the image is formed by using the active ray-curable liquid composition, but the type of the liquid composition used for forming the image is not particularly limited, and the activity of water-based or solvent-based is not particularly limited. It may be a liquid composition that is not cured by irradiation with a line.

Further, in the above description, the first irradiation unit 230 irradiates the intermediate image with the active rays, but when the permeation of the liquid composition does not pose a problem, the first irradiation unit 230 irradiates the intermediate image. Irradiation of active rays may be omitted.

3. 3. Image Forming Method A third embodiment of the present invention relates to an image forming method using an intermediate transfer member according to the first embodiment described above. The image forming method can be carried out, for example, by using the image forming apparatus according to the second embodiment described above.

FIG. 3 is a flowchart of an image forming method according to the present embodiment. The image forming method includes a step of applying an active ray-curable liquid composition to the surface of the intermediate transfer body to form an intermediate image (step S110), and the activity imparted to the surface of the intermediate transfer body. A step of irradiating the linear curable liquid composition with active rays (step S120), and a step of transferring an intermediate image containing the thickened active ray curable liquid composition to a recording medium (step S130). It has a step (step S140) of irradiating an intermediate image transferred to a recording medium with active rays to main-cure the active ray-curable liquid composition.

In the step of forming the intermediate image (step S110), the active ray-curable liquid composition is applied to the surface of the intermediate transfer material according to the first embodiment to form the intermediate image.

The method for forming the intermediate image is not particularly limited, and known methods such as spray coating, dipping method, screen printing, gravure printing, offset printing, and inkjet method can be used, but the active ray-curable liquid composition. When forming an image by an inkjet method, which forms an image in which dots formed by droplets are aggregated, the present embodiment remarkably achieves curing capable of suppressing ink penetration.

In the step of irradiating the active ray-curable liquid composition with the active ray (step S120), the active ray is irradiated on the surface of the intermediate transfer body on which the intermediate image is formed.

At this time, the irradiation amount of the active energy rays on the intermediate image should be such that the active ray-curable liquid composition constituting the intermediate image can maintain sufficient wettability with respect to the recording medium at the time of transfer to the recording medium. Just do it. The amount of active rays irradiated to the intermediate image is such that the viscosity of the intermediate image is 5 × 10 ⁶ mPa · s or more and 2 × 10 ⁸ mPa · s or less, preferably 1 × 10 ⁷ mPa · s or more and 1 × 10 ⁸ mPa · s. It is preferable to control so as to be as follows.

Further, from the viewpoint of suppressing the penetration of the liquid composition into the inside of the surface layer before irradiating the intermediate image with the active rays in the present step, the active rays in the present step are applied after the liquid composition is applied in the previous step. The interval until irradiation is preferably shorter, for example, it can be 10 milliseconds or more and 10 seconds or less, and it is preferable that it is 10 milliseconds or more and 5 seconds or less.

In the step of transferring to a recording medium (step S130), the intermediate image formed on the surface of the intermediate transfer body is transferred to the surface of the recording medium. For example, the surface of the intermediate transfer body on which the intermediate image is formed and the surface of the recording medium on which the image should be formed may be brought into contact with each other and pressed from the intermediate transfer body side to the recording medium side.

In the step of curing the active ray-curable liquid composition (step S140), the active ray-curable liquid composition transferred to the recording medium is irradiated with active rays to obtain the active ray-curable liquid composition. This cure. As a result, an image is formed on the recording medium.

In the above description, an intermediate image is formed on the surface of the intermediate transfer body by an inkjet method, but the method for forming the intermediate image is not particularly limited, and spray coating, immersion method, screen printing, gravure printing, and offset printing are used. A known method such as can be used. Among these methods, the effect of suppressing the penetration of the liquid composition by the intermediate transfer material is remarkably exhibited at the time of image formation by the inkjet method for forming an image in which dots formed by droplets of the inkjet ink are aggregated.

Further, in the above description, the image is formed by using the active ray-curable liquid composition, but the type of the liquid composition used for forming the image is not particularly limited, and the activity of water-based or solvent-based is not particularly limited. It may be a liquid composition that is not cured by irradiation with a line.

Further, in the above description, the intermediate image formed on the surface of the intermediate transfer body is irradiated with the active line, but when the immersion of the liquid composition does not cause a permeation problem, the active line to the intermediate image is applied. Irradiation may be omitted.

Hereinafter, specific examples of the present invention will be described together with comparative examples, but the present invention is not limited thereto.

1. 1. Preparation of intermediate transcript 1-1. Preparation of intermediate transfer material 1 (preparation of base material)
A base material is formed by adding carbon black "SPECIAL BLACK4" (manufactured by Degussa) to the polyamide-imide varnish "HR-16NN" (manufactured by Toyobo Co., Ltd., solid content concentration 14% by mass) and mixing using a mixer. A coating solution for use was prepared. The amount of carbon black added was 19 parts by mass with respect to 100 parts by mass of the resin component (solid content) of the polyamide-imide varnish.

A stainless steel cylindrical mold and a dispenser having a nozzle and capable of quantitatively discharging a liquid were prepared. While rotating the mold around the axis of the cylinder, while moving the nozzle in the axial direction, the coating liquid for forming the base material is discharged from the nozzle to apply it spirally on the outer peripheral surface of the mold, and they are connected. A coating film was formed. Then, while rotating the cylindrical mold, it was heated at 100 ° C. for 1 hour to volatilize most of the solvent, and then heated to 250 ° C. and held for 1 hour to form an endless belt-shaped base material. .. The thickness of the formed base material was 65 μm.

(Preparation of elastic layer)
Silicone rubber (Shin-Etsu Chemical Co., Ltd., product name KE-2061-30) with respect to 100 parts by weight of carbon black (manufactured by Asahi Carbon Co. # 80) 40 parts by weight, of aluminum oxide _{(Al 2} O 3) 30 parts by weight, An elastic material was prepared by kneading 5 parts by mass of magnesium oxide (MgO), 10 parts by mass of zinc oxide (ZnO), and 15 parts by mass of silicon oxide (SiO).

The elastic material was dissolved and dispersed in toluene so that the solid content concentration was 20% by mass to prepare a coating liquid for forming an elastic layer.

An elastic layer forming coating liquid was applied onto the endless belt-shaped base material produced above in the same manner as the base material forming coating liquid to form a coating film covering the outer peripheral surface of the base material. Next, the cylindrical mold was heated at 50 ° C. for 1 hour while rotating to volatilize most of the solvent, and then heated to 170 ° C. and held for 20 minutes for cross-linking to form an elastic layer. The thickness of the formed elastic layer was 200 μm.

(Preparation of surface layer)
90 parts by mass of a fluorine-based monomer (manufactured by AGC Cortec, product name Obrigado SS-0054 (“Obligard” is a registered trademark of the company)) is dissolved in solvent THF so that the solid content concentration is 50% by mass. As a filler, 9 parts by mass of calcium carbonate (Viscoexcel-30 manufactured by Shiraishi Calcium Co., Ltd., average value of maximum particle size 30 nm) was added, and as a compatibilizer, N-261A (manufactured by Kao Co., Ltd., Product name N-261A) 0.2 parts by mass was added to prepare a coating solution for forming a surface layer.

On the outer peripheral surface of the elastic layer produced above, a coating liquid for forming a surface layer is spray-coated using a spray device manufactured by YD Mechatronics Solutions Co., Ltd. so that the dry film thickness is 28 μm under the following coating conditions. To form a coating film. The intermediate transfer material 1 was prepared by irradiating this coating film with ultraviolet rays as active energy rays under the following irradiation conditions and curing the coating film to form a surface layer. The irradiation of ultraviolet rays was performed while fixing the light source and rotating the base material on which the coating film was formed on the outer peripheral surface of the elastic layer.

-Spray application conditions-
Nozzle scan speed: 1-10 mm / sec
Nozzle distance: 100-150 mm
Number of nozzles: 1
Coating liquid supply amount: 1 to 5 mL / min
O ₂ flow rate: _{2 to 6} L / min
-Ultraviolet irradiation conditions-
Type of light source: High-pressure mercury lamp "H04-L41" (manufactured by Eye Graphics Co., Ltd.)
Distance from the irradiation port to the surface of the coating film: 100 mm
Irradiation light intensity: 1 J / cm ²
Irradiation time (time for rotating the base material): 240 seconds

1-2. Preparation of Intermediate Transfer 2 Intermediate transfer in the same manner as in the preparation of Intermediate Transfer 1 except that the filler used to prepare the surface layer was talc (manufactured by Matsuo Sangyo Co., Ltd., Micro Ace, average maximum particle size of 20 nm). Body 2 was made.

1-3. Preparation of Intermediate Transfer 3 As the silicone rubber used to prepare the elastic layer, KE-1950-30 and KE-2061-30 manufactured by Shin-Etsu Chemical Co., Ltd. were used in combination (mixing ratio: KE-1950-30 / KE). -2061-30 = 10/90), except that the filler used to prepare the surface layer was mica (manufactured by Matsuo Kogyo Co., Ltd., A-11 was crushed and the average maximum particle size was 800 nm). The intermediate transfer material 3 was prepared in the same manner as the preparation.

1-4. Preparation of Intermediate Transfer Material KE-1950-30 and KE-2061-30 are used in combination as the silicone rubber used to prepare the elastic layer (mixing ratio: KE-1950-30 / KE-2061-30 = 20 /). 80), the intermediate transfer body 4 was prepared in the same manner as in the preparation of the intermediate transfer body 1 except that the filler used for preparing the surface layer was silica (manufactured by Aerosil Co., Ltd., RX-50, average value of the maximum particle size of 50 nm). Made.

1-5. Preparation of Intermediate Transfer Material KE-1950-30 and KE-2061-30 are used in combination as the silicone rubber used to prepare the elastic layer (mixing ratio: KE-1950-30 / KE-2061-30 = 50 /). 50) Intermediate transfer in the same manner as in the preparation of the intermediate transfer material 1 except that the filler used for preparing the surface layer was a mixture of the above calcium carbonate and the above silica (average value of the maximum particle size as a filler was 39 nm). Body 5 was made.

1-6. Preparation of Intermediate Transfer Body 6 The intermediate transfer body 6 was prepared in the same manner as the preparation of the intermediate transfer body 1 except that the amount of the filler used for the preparation of the surface layer was 2 parts by mass.

1-7. Preparation of Intermediate Transfer Body 7 The intermediate transfer body 7 was prepared in the same manner as the preparation of the intermediate transfer body 1 except that the compatibilizer was not added to the surface layer forming coating solution used when the surface layer was prepared.

1-8. Preparation of Intermediate Transfer 8 KE-1950-30 and KE-2061-30 are used in combination as the silicone rubber used to prepare the elastic layer (mixing ratio: KE-1950-30 / KE-2061-30 = 10 /). 90) The intermediate transfer body 8 was produced in the same manner as the production of the intermediate transfer body 1 except that the thickness of the surface layer was 33 μm.

1-9. Preparation of Intermediate Transfer 9 The silicone rubber used to prepare the elastic layer was changed to KE-1950-30, the amount of the filler used to prepare the surface layer was 25 parts by mass, and the amount of the compatibilizer added was 5. The intermediate transfer material 9 was produced in the same manner as in the production of the intermediate transfer material 1 except that the parts were made by mass.

1-10. Preparation of Intermediate Transfer 10 KE-1950-30 and KE-2061-30 are used in combination as the silicone rubber used to prepare the elastic layer (mixing ratio: KE-1950-30 / KE-2061-30 = 10 /). 90) The intermediate transfer body 10 was produced in the same manner as the production of the intermediate transfer body 1 except that the thickness of the elastic layer was set to 1100 μm.

1-11. Preparation of Intermediate Transfer 11 As the silicone rubber used to prepare the elastic layer, KE-1950-30 and KE-2061-30 are used in combination (mixing ratio: KE-1950-30 / KE-2061-30 = 50/50). The intermediate transfer body 11 was prepared in the same manner as in the preparation of the intermediate transfer body 1 except for the above.

1-12. Preparation of Intermediate Transfer Material KE-1950-30 and KE-2061-30 are used in combination as the silicone rubber used to prepare the elastic layer (mixing ratio: KE-1950-30 / KE-2061-30 = 50/50). The intermediate transfer body 12 was prepared in the same manner as in the preparation of the intermediate transfer body 1 except for the above.

1-13. Preparation of Intermediate Transfer 13 The filler used to prepare the surface layer was a mixture of the above-mentioned calcium carbonate and the above-mentioned silica (the average value of the maximum particle size as the filler was 36 nm), and the amount of the filler added to prepare the surface layer was adjusted. The intermediate transfer body 13 was produced in the same manner as in the production of the intermediate transfer body 1 except that the weight was 15 parts by mass.

1-14. Preparation of Intermediate Transfer 14 The same as the preparation of Intermediate Transfer 1 except that the filler used to prepare the surface layer was a glass filler (EMB-10 manufactured by Potters Barotini, average maximum particle size of 1200 nm). To prepare the intermediate transcript 14.

1-15. Preparation of Intermediate Transfer 15 An intermediate transfer 15 was prepared in the same manner as in the preparation of the intermediate transfer 1 except that no filler was added to the coating liquid for forming the surface layer used when the surface layer was prepared.

2. Measurement of intermediate transcript 2-1. Rubber strength of elastic layer When the elastic layer was prepared, a micro rubber hardness tester (MD-1 hardness tester type A: manufactured by Kogaku Keiki Co., Ltd., MD-1 capa) was used to determine the hardness of 10 points on the surface of the elastic layer. Was measured, and the average value was taken as the rubber strength of the elastic layer.

2-2. Tension elastic modulus of binder resin The binder resin used to form the surface layer was used as a test piece of dumbbell-shaped No. 1 (JIS K 6251 (2017)) having a thickness of 30 to 80 μm, and was pulled at a tensile speed of 200 mm / min. The stress during tension and the strain at that time were measured. Then, the value obtained by dividing the difference in stress between the point where the strain is 0.05 (%) and the point where the strain is 0.25 (%) by the difference in strain at the above two points is the value of the surface layer. The tensile elastic modulus was used.

2-3. Angle of contact of pure water with the surface layer A sample of 10 mm × 10 mm size was cut from any 5 points on the surface layer, and foreign matter adhering to the surface was wiped off with alcohol to prepare a measurement sample. Then, using a fully automatic contact angle meter "DM-901" (manufactured by Kyowa Interface Science Co., Ltd.), the contact angle is measured under the following measurement conditions, and the average value thereof is the contact angle of pure water to the surface layer. And said.
Measurement method: Sessile drop method Measurement liquid: Pure water Number of measurements: 4 times

Types and amounts of materials (elastic layer: resin type, surface layer: filler and compatibilizer) used to prepare the intermediate transfer bodies 1 to 15, as well as the rubber strength of the elastic layer, the tensile elastic modulus of the surface layer and Table 1 shows the measurement results of the contact angle of pure water with the surface layer.

3. 3. Evaluation 3-1. Permeability The intermediate transfer material is cut out from the surface layer side, and a sheet-shaped test piece of 20 cm × 20 cm × 2 mm is prepared. The mass M1 of the test piece was measured in advance. 10 cc of toluene was applied to the surface of the test piece on the surface layer side, and the test piece was left in a closed space (30 × 30 × 10 cm vat) in an environment of 25 ° C. for 1 hour. Then, the test piece was taken out, and the mass M2 of the test piece was measured after removing the solvent that had not penetrated into the inside with a metal blade or the like. The weight increase rate (M2 / M1) (%) at this time was determined and used as an evaluation value of permeability. An intermediate transcript having an increase rate of less than 105% was evaluated as "◯", and an intermediate transcript having an increase rate of 105% or more was evaluated as "x".

3-2. Concavo-convex followability (preparation of ink)
The pigment dispersant, photopolymerizable compound, and polymerization inhibitor shown below were placed in a stainless steel beaker and heated and stirred for 1 hour while heating on a hot plate at 65 ° C.
Pigment Dispersant: Azisper PB824 (manufactured by Ajinomoto Fine-Techno) 9 parts by mass Photopolymerizable compound: Tripropylene glycol diacrylate 70 parts by mass Polymerization inhibitor: Irgastab UV10 (manufactured by Ciba Japan) 0.02 parts by mass

After cooling the above mixed solution to room temperature, 21 parts by mass of Pigment Red 122 (Chromofine Red 6112JC manufactured by Dainichiseika) was added thereto. The mixed solution was placed in a glass bottle together with 200 g of zirconia beads having a diameter of 0.5 mm, sealed, and dispersed with a paint shaker for 8 hours. Then, the zirconia beads were removed to prepare a pigment dispersion.

The following photopolymerizable compound, photopolymerization initiator, polymerization inhibitor, surfactant, and pigment dispersant 1 were mixed, heated to 100 ° C., and stirred. Then, the obtained liquid was filtered with a metal mesh filter of # 3000 under heating and then cooled to prepare an ink.
Photopolymerizable compound: Polyethylene glycol # 400 diacrylate 29.8 parts by mass Photopolymerizable compound: 4EO-modified pentaerythritol tetraacrylate 15.0 parts by mass Photopolymerizable compound: 6EO-modified trimethyl propantriacrylate 23.0 parts by mass Light Polymerization Initiator: DAROCUR TPO (manufactured by BASF) 6.0 parts by mass Photopolymerization initiator: ITX (manufactured by DKSH Japan) 1.0 part by mass Photopolymerization initiator: DAROCUR EDB (manufactured by BASF) 1.0 part by mass Polymerization Inhibitor: Irgastab UV10 (manufactured by Ciba Japan) 0.1 parts by mass Surfactant: KF-352 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.1 parts by mass Gelling agent: distearylketone (Kao Co., Ltd. product, Kao) Wax T1) 5.0 parts by mass Pigment dispersion: 19.0 parts by mass

(Image formation)
The ink was loaded into the head carriage of an image forming apparatus equipped with a piezo type line head type inkjet head to form a monochromatic image. The ink supply system shall consist of an ink tank, a supply pipe, an anterior chamber ink tank immediately before the recording head, a pipe with a filter, and a piezo head. Insulate from the anterior chamber ink tank of the ink supply system to the recording head portion, and 80 It was heated to ° C. In addition, the piezo head also had a built-in heater to heat the ink in the recording head.

Further, in the inkjet head, piezo heads having a nozzle diameter of 24 μm and a resolution of 512 dpi were arranged in a staggered manner to achieve a recording resolution of 1200 dpi × 1200 dpi. The amount of magenta ink droplets ejected from the head was 3.5 pl per droplet, and the droplet ejection speed was 6 m / sec.

The ink was ejected from an inkjet head arranged on the surface of the intermediate transfer body, and 10 pl droplets were landed in a grid pattern at 100 μm intervals. The inkjet head was arranged at a position where the distance from the surface of the intermediate transfer body to the nozzle was 2 mm. After that, in some tests, LED lamps (385 nm manufactured by Hamamatsu Photonics Co., Ltd., distance between recording medium and lamp 2 mm, maximum output 3800 mW / cm ² (ultraviolet integrated photometer manufactured by Hamamatsu Photonics Co., Ltd.) were applied to ink droplets on the intermediate transfer body. : Measured with C9536-02)) to irradiate ultraviolet rays to temporarily cure the ink. Next, a recording medium (Rezac 66, basis weight: 302 gsm) was brought into contact with the surface of the intermediate transfer body, and a pressure of 100 kPa / m ² was applied in the thickness direction of the intermediate transfer body for 10 seconds to transfer the ink to the recording medium. .. After that, a field of view of 5 mm × 5 mm on the surface of the recording medium was observed, and the number of dots transferred to the recording medium (n1) and the number of dots not transferred to the recording medium (n2) were determined. .. The transfer rate (n1 / (n1 + n2)) (%) at this time was determined and used as an evaluation value for unevenness followability. An intermediate transcript having a transcription rate of 90% or more was evaluated as "◯", and an intermediate transcript having a transcription rate of less than 90% was evaluated as "x".

Table 2 shows the evaluation results of permeability and unevenness followability. Table 2 also shows the unevenness tracking property with and without ultraviolet irradiation at the time of image formation.

As is clear from Tables 1 and 2, it has a base material layer, an elastic layer and a surface layer, the surface layer is 90 parts by mass or more and 99 parts by mass or less, and the tensile elastic modulus is 0.1 MPa or more and 20 MPa or less. In the intermediate transfer bodies 1 to 12, which have a binder resin and a filler having an average maximum particle size of 10 nm or more and 1000 nm or less, which is 1 part by mass or more and 10 parts by mass or less, ink penetration is suppressed and The transfer rate was also high.

The intermediate transfer body of the present invention can be suitably used for image formation and pattern formation using the intermediate transfer body, and can be particularly preferably used for image formation by the inkjet method.

100 Intermediate transfer member 110 Base material layer 120 Elastic layer 130 Surface layer 200 Image forming device 210 Transport path 220 Composition application part 230 First irradiation part 240 Transfer part 252, 254, 256 Support roller 260 Second irradiation part 270 Cleaning part 300 recoding media

Claims (14)

An intermediate transfer body having a base material layer, an elastic layer and a surface layer, to which a liquid composition is applied and for transferring the applied liquid composition to a recording medium.
The surface layer is
A binder resin having a tensile elastic modulus of 0.1 MPa or more and 20 MPa or less, which is 90 parts by mass or more and 99 parts by mass or less.
Fillers with an average maximum particle size of 10 nm or more and 1000 nm or less, which are 1 part by mass or more and 10 parts by mass or less.
(The total mass of the binder resin and the filler is 100 parts by mass.)
An intermediate transcript having. The intermediate transfer according to claim 1, wherein the surface layer contains a compatibilizer in an amount of 0.1 parts by mass or more and 3 parts by mass or less when the total amount of the binder resin and the filler is 100 parts by mass. body. The intermediate transfer product according to claim 1 or 2, wherein the surface layer has a thickness of 1 μm or more and 30 μm or less. The intermediate transfer material according to any one of claims 1 to 3, wherein the elastic layer has a rubber hardness of 8 ° or more and 40 ° or less and a thickness of 200 μm or more and 1000 μm or less. The intermediate transfer product according to any one of claims 1 to 4, wherein the elastic layer contains silicone rubber. The intermediate transfer product according to any one of claims 1 to 5, wherein the filler contains at least one filler selected from the group consisting of calcium carbonate, mica, talc and silica. The intermediate transfer product according to any one of claims 1 to 6, wherein the surface layer has a contact angle of pure water of 60 ° or less. The intermediate transfer product according to any one of claims 1 to 7, which is an intermediate transfer material used for imparting the liquid composition by an inkjet method. The intermediate transcript according to any one of claims 1 to 8 and
A composition-imparting portion that imparts a liquid composition to the intermediate transcript,
A transfer unit that transfers the liquid composition applied to the intermediate transfer body to a recording medium, and
An image forming apparatus having. The image forming apparatus according to claim 9, further comprising an irradiation unit that irradiates the liquid composition applied to the intermediate transfer body with active rays. The image forming apparatus according to claim 9 or 10, wherein the composition-imparting unit imparts the liquid composition to the intermediate transfer material by an inkjet method. The step of applying the liquid composition to the intermediate transcript according to any one of claims 1 to 8.
A step of transferring the liquid composition applied to the intermediate transfer body to a recording medium, and
An image forming method having. The image forming method according to claim 12, wherein the liquid composition is an active ray-curable composition, and comprises a step of irradiating the liquid composition applied to the intermediate transfer body with active rays. The image forming method according to claim 12 or 13, wherein the liquid composition is applied to the intermediate transfer body by an inkjet method.

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