Seamless belt, inkjet conveying belt, recording medium conveying device, and inkjet recording device

Abstract

To provide a seamless belt having a plurality of through holes and excellent cleaning properties against adhering ink, an inkjet conveying belt, a recording medium conveying device, and an inkjet recording device.SOLUTION: There are provided a seamless belt 100, an inkjet conveying belt, a recording medium conveying device, and an inkjet recording device, the seamless belt 100 having a base material layer 101 having a plurality of through holes 102 and a photocatalyst layer 103. The photocatalyst layer 103 is provided on an inner circumferential surface of the base material layer 101 and on a side surface of the through hole 102, and the photocatalyst layer 103 on the side surface of the through hole 102 is provided in a range starting from the inner circumferential surface on which the photocatalyst layer 103 is provided and not reaching an outer circumferential surface.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a seamless belt, an inkjet transport belt, a recording medium transport device, and an inkjet recording device. [Background technology]

[0002] Inkjet recording devices can form an image (ink image) by depositing ink containing coloring materials onto a recording medium such as paper. One type of inkjet recording device is a line head type inkjet recording device that has recording heads of each color arranged along a recording medium transport path. This inkjet recording device is provided with a recording medium transport unit that transports the recording medium by a transport belt, and ink is ejected from each recording head onto the recording medium during transport. Known configurations for this conveying belt include a configuration in which the conveying belt is charged and the recording medium is electrostatically attracted to the conveying belt using static electricity, and a configuration in which the recording medium is attracted to the conveying belt by suction through a number of through holes formed in the conveying belt. Patent Document 1 proposes a belt cleaning device for cleaning both the front and back surfaces of a suction conveyor belt having a plurality of through holes. Patent Document 2 proposes a cleaning device for an electrostatic attraction member in which a photocatalyst layer is provided on the surface of an electrostatic attraction transport belt. The cleaning device for an electrostatic attraction member includes a means for irradiating the photocatalyst layer with active light to activate the photocatalyst layer, a means for adding moisture to the photocatalyst layer, and a cleaning means for cleaning the surface to which moisture has been added. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-189352 A [Patent Document 2] JP 2010-150017 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, according to the studies of the present inventors, the following problems were found in each of Patent Document 1 and Patent Document 2. In the belt cleaning device described in Patent Document 1, a cleaning roller including a porous body and a nonwoven fabric is used to clean both sides of a conveyor belt having a plurality of through holes. However, some of the dirt adhering to the conveyor belt is gradually pushed by the cleaning roller to the inner side of the through holes and accumulates there, causing the through holes to become smaller. As a result, the conveyor belt loses its suction and adsorption power for the recording medium, and it has been found that the conveyor belt is affected by the passage of time.

[0005] In addition, in the cleaning device for electrostatic adsorption members described in Patent Document 2, active light is irradiated onto a photocatalyst layer provided on the outer peripheral surface of a conveyor belt, moisture is applied to the conveyor belt surface (photocatalyst layer) to lift up dirt, and the conveyor belt surface is then cleaned with a cleaning member (blade). However, the electrostatic adsorption conveyor belt has a problem in that the adsorption force is weaker than that of the suction adsorption method of Patent Document 1. Therefore, it is conceivable to use a suction conveyor belt having a plurality of through holes as in Patent Document 1 as the conveyor belt, and to combine the formation of the photocatalytic layer as in Patent Document 2 with a cleaning device using a moisture providing means and a cleaning member in order to improve the cleaning performance of ink, etc. However, even in this case, it is conceivable that part of the contaminated water reaches the back surface through the through holes due to the blade cleaning and adheres to the belt roller that drives the conveyor belt, affecting the conveyance performance of the belt. Also, as in Patent Document 1, it is conceivable that contaminants adhere to the side of the through holes, weakening the suction adsorption force, and affecting the conveyance of the recording medium.

[0006] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS OF THE PRESENT DISCLOSURE An object of the present invention is to provide a seamless belt having a plurality of through holes, which is excellent in cleaning ability of adhering ink, a conveying belt for ink jet recording, a recording medium conveying device, and an ink jet recording device. [Means for solving the problem]

[0007] The above object can be achieved by the present invention described below. That is, the seamless belt according to one aspect of the present invention is A seamless belt having a base layer having a plurality of through holes and a photocatalyst layer, The photocatalyst layer is provided on an inner circumferential surface of the base layer and on a side surface of the through hole, The photocatalytic layer on the side surface of the through hole is characterized in that it is provided in an area starting from the inner circumferential surface on which the photocatalytic layer is provided and not reaching the outer circumferential surface. Further, an inkjet transport belt according to an aspect of the present invention includes the seamless belt described above.

[0008] Furthermore, a recording medium transporting device according to one aspect of the present invention is a recording medium transporting device including the above-mentioned inkjet transport belt, a transport plate having an opening that contacts the inner surface of the transport belt, and a suction section that adsorbs the recording medium to the transport belt by sucking air from the transport plate, and further including a belt cleaning device that cleans the inkjet transport belt, the belt cleaning device comprising: a light irradiation means that irradiates active light that activates the photocatalyst layer; a moisture addition means that adds moisture to the inner surface of the inkjet transport belt; and a cleaning means that cleans the inner surface of the inkjet transport belt to which moisture has been added by the moisture addition means.

[0009] Further, an inkjet recording apparatus according to an aspect of the present invention includes the recording medium transport device described above, and an image forming apparatus that forms an image on the recording medium. Effect of the Invention

[0010] According to the present invention, it is possible to provide a seamless belt having a plurality of through holes, which has excellent cleaning properties against adhering ink, an inkjet transport belt, a recording medium transport device, and an inkjet recording device. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing a cross section of an inkjet transport belt which is one embodiment of a seamless belt of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing an example of the configuration of a recording medium transport device and a belt cleaning device according to an embodiment of the present invention. [Diagram 3] 1 is a schematic diagram illustrating an example of a configuration of an inkjet recording apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will be described in detail below with reference to preferred embodiments. It was confirmed that if a photocatalyst layer is not formed on the inner surface of the through hole, contaminants adhere to the inner surface of the through hole, weakening the suction and adsorption force, affecting the transport of the recording medium. Also, it was confirmed that if a photocatalyst layer is formed on the entire inner surface of the through hole, contaminated water easily reaches the opposite side of the photocatalyst layer, affecting the transportability of the transport belt and the transportability of the recording medium. The seamless belt used in the conveyor belt according to the present invention is A seamless belt having a base layer having a plurality of through holes and a photocatalyst layer, The photocatalyst layer is provided on an inner circumferential surface of the base layer and on a side surface of the through hole, The photocatalytic layer on the side surface of the through hole is characterized in that it is provided in an area starting from the inner circumferential surface on which the photocatalytic layer is provided and not reaching the outer circumferential surface.

[0013] <Seamless belts and inkjet conveyor belts> 1 is a schematic diagram showing a cross section of an inkjet transport belt, which is one embodiment of the seamless belt of the present invention. The inkjet transport belt of the present invention is made of a seamless belt 100 (endless tubular belt) of the present invention. The seamless belt 100 has a base material layer 101 and a photocatalyst layer 102. The base layer 101 may be made of metal or resin. If it is made of metal, stainless steel is generally used. If it is made of resin, it may be made of a single resin or multiple resins. If it is made of resin, examples of the resin include one or a combination of multiple resins such as polyimide (PI), polyamideimide (PAI), polyvinylidene fluoride (PVDF), ethylene-tetrafluoroethylene copolymer (ETFE), polycarbonate (PC), and polyethylene terephthalate (PET). The base layer 101 may also have an elastic layer made of rubber such as ethylene propylene rubber (EPDM), polyurethane resin, and nitrile rubber (NBR). It is also preferable that the base layer 101 is conductive.

[0014] The thickness of the base layer 101 is not particularly limited since it differs depending on the size of the device, but is preferably 50 μm or more and 1000 μm or less, and more preferably 50 μm or more and 500 μm or less.

[0015] Furthermore, the seamless belt 100 has a plurality of through holes 102 in the base layer 101 for sucking air in order to adhere the recording medium to the conveyor belt. The shape of the through holes 102 is preferably a round hole. The size of the through holes 102 is not critical as long as it does not affect the inkjet image formation, and is preferably 0.1 mm to 3 mm, more preferably 0.1 mm to 1 mm, and even more preferably 0.1 mm to 0.5 mm.

[0016] The arrangement of the through holes 102 is preferably a parallel arrangement or a staggered arrangement, and the hole pitch is preferably 5 mm or less, more preferably 3 mm or less, within a range that does not affect the suction and adsorption of the recording medium. Note that the hole pitch refers to the distance between the center points of the through holes, and the lower limit is greater than the hole size of the through holes and is within a range that does not impair the mechanical strength of the conveyor belt.

[0017] The seamless belt 100 has a photocatalyst layer 103. The photocatalyst layer 103 is provided on the inner circumferential surface of the base layer 101, which is difficult to clean manually.

[0018] As shown in FIG. 1, the photocatalyst layer 103 is also formed on the side of the through hole 102 of the base layer 101. The photocatalyst layer 103 is also provided on the inner side in a range that does not reach the outer circumferential surface of the through hole 102, that is, a range shorter than the thickness of the base layer, starting from the inner circumferential surface of the base layer 101 on which the photocatalyst layer 103 is provided. As will be described later, by irradiating the inner circumferential surface of the base layer 101 with light, the photocatalyst layer 103 coated on the base layer 101 is activated to improve the hydrophilicity, and the surface of the photocatalyst layer 103 can be made superhydrophilic. After that, when moisture is applied to the inner circumferential surface of the base layer 101, since the hydrophilicity of the photocatalyst layer 103 has been increased by the light irradiation first, the moisture spreads over the entire surface on which the photocatalyst layer 103 is formed. At the same time, since the photocatalyst layer 103 is in a superhydrophilic state, moisture can get between the dirt such as ink and the photocatalyst layer 103, and the dirt can be lifted up. Then, the dirt and moisture can be removed by a cleaning means.

[0019] In this case, if the photocatalyst layer 103 is formed on the entire inner surface of the through hole 102, moisture will reach the outer peripheral surface through the through hole 102 as the hydrophilicity improves, and this will affect the subsequent transportation of the recording medium. Therefore, it is not desirable to form the photocatalyst layer 103 on the entire side surface of the through hole 102.

[0020] The photocatalyst layer 103 is formed by mixing photocatalyst particles with an appropriate binder, and optionally other components such as pigments, beads, dispersants, etc., using a stirrer or the like to form a photocatalyst layer-forming composition, and then applying this to the base layer 101. Examples of photocatalyst particles include the following particles. A photocatalytic metal selected from titanium, zinc, platinum, palladium, strontium, tungsten, niobium, tantalum, cadmium, iron, ruthenium, cobalt, rhodium, iridium, nickel, gold, copper and silver. Composites and oxides of said metals. Among these, titanium oxide particles are preferred because of their high photocatalytic activity and versatility.The particle size of the photocatalyst particles is preferably 5 nm or more and 100 nm or less from the viewpoint of layer formation. As the binder, a thermosetting resin, an ultraviolet-curing resin, a catalyst-curing resin, a multi-liquid reaction resin, a moisture-curing resin, an oxidation polymerization resin, or the like can be preferably used.

[0021] The content (mass %) of photocatalyst particles in the photocatalyst layer-forming composition is preferably 3 mass % or more and 50 mass % or less, and more preferably 5 mass % or more and 30 mass % or less, based on the total mass of the photocatalyst layer-forming composition.

[0022] The method for applying the photocatalyst layer-forming composition is not particularly limited, and examples thereof include dip coating, spray coating, flow coating, shower coating, roll coating, and spin coating. The photocatalyst layer-forming composition can be cured by any method without particular limitation, and can be cured by heat or radiation (light, electron beam, etc.).

[0023] The thickness of the photocatalyst layer 103 can be appropriately changed depending on the thickness of the seamless belt, the size of the through holes 102, and the size of the photocatalyst particles, but is preferably 30 μm or more and 100 μm or less. When the thickness of the base layer 101 is T, the length L (the distance from the inner surface to the outer surface) of the photocatalyst layer 103 provided on the side of the through hole 102 is preferably 0.2T / or more and 0.8T / or less from the viewpoint of cleaning ability. As a means for controlling the length of the photocatalytic layer 103 in the through-hole 102 and a means for preventing it from reaching the outer peripheral surface, for example, the following methods (1) and (2) can be mentioned. (1): A method in which the photocatalytic layer 103 is formed after a part of the side surface of the through-hole 102 is masked. (2): A method in which the photocatalytic layer 103 is formed on the entire side surface of the through-hole 102 and then partially removed by etching or the like.

[0024] <Recording medium transport device and belt cleaning device> FIG. 2 is a schematic diagram showing an example of the configuration of a recording medium transport device and a belt cleaning device (hereinafter, collectively referred to as a recording medium transport device) in one embodiment of the present invention. 2, the recording medium conveying device 200 of this embodiment includes the seamless belt conveying belt 100, a driving roller 201, a support roller 202, and tension rollers 203a and 203b. Also, the inner peripheral surface side of the conveying belt 100 includes a conveying plate 204, a filter 205, a suction unit 206, and a belt cleaning device 207. The conveying belt 100 has a photocatalyst layer 103 formed on the inner peripheral surface side.

[0025] The conveyor belt 100 is stretched with a predetermined tension by a drive roller 201, a support roller 202, and tension rollers 203a and 203b. By the rotation of the drive roller 201 in the direction of the arrow, the conveyor belt 100 runs in the conveying direction A shown in FIG. 2, and can convey the recording medium in the conveying direction A.

[0026] The conveying plate 204 is a guide member that supports the conveying belt 100 and has an opening. The recording medium is sucked onto the conveying belt 100 by negative pressure via the through holes 102 of the conveying belt 100 and the opening of the conveying plate 204. This prevents the recording medium from floating, and also prevents wrinkles and wavy deformations that occur on the surface of the recording medium during conveyance, thereby maintaining the flatness of the recording medium.

[0027] The opening shape of the conveying plate 204 is preferably a shape that can ensure the suction property and flatness of the recording medium. A preferable shape is a configuration that reduces the contact area with the conveying belt 100, such as a lattice shape, in order to reduce friction between the conveying plate 204 and the conveying belt 100.

[0028] The suction unit 206 applies negative pressure via the through holes 102 of the conveyor belt 100 and the openings of the conveyor plate 204, and sucks and adheres the recording medium onto the conveyor belt 100. The filter 205 is provided between the conveyor plate 204 and the suction unit 206 to prevent ink mist, paper powder, and the like from being sucked into the suction unit 206 through the through holes 102 and damaging the suction unit.

[0029] The belt cleaning device 207 includes a light irradiating means 207a for activating the photocatalyst layer 103, a moisture providing means 207b, and a cleaning means 207c.

[0030] The light irradiation means 207a includes a light source (not shown) that emits light with a wavelength that activates the photocatalyst layer 103. Since the wavelength of the light that activates the photocatalyst differs depending on the type of photocatalyst that constitutes the photocatalyst layer 103, a light source that emits light with a wavelength according to the type of photocatalyst is used. For example, titanium oxide (TiO2) is activated by light with a wavelength of about 365 nm, and tungsten oxide (WO3) is activated by visible light with a wavelength of 400 nm or more and 600 nm or less.

[0031] The light irradiation means 207a irradiates the inner peripheral surface of the conveyor belt 100 with light, thereby activating the photocatalyst layer 103 provided on the inner peripheral surface of the conveyor belt 100. When the photocatalyst layer 103 is activated, the hydrophilicity is improved, and the surface of the photocatalyst layer 103 can be made superhydrophilic.

[0032] The moisture applying means 207b has a function of supplying moisture to the inner circumferential surface of the conveyor belt 100, and is appropriately selected depending on the size of the device, etc., and is not particularly limited. For example, there are means for directly supplying moisture such as spray application, ultrasonic vibration mist application, and heated steam application, and means for applying moisture by pressing a porous roller containing moisture against the surface.

[0033] The moisture supplied from the moisture supplying means 207b to the inner peripheral surface of the conveyor belt 100 in this manner spreads over the entire surface on which the photocatalyst layer 103, which has been previously irradiated with light from the light irradiating means 207a and has become more hydrophilic, has been formed. At the same time, since the photocatalyst layer 103 is in a superhydrophilic state, moisture penetrates between the stains such as ink and the photocatalyst layer 103, and can lift off the stains.

[0034] The cleaning means 207c is disposed on the inner circumferential surface of the conveyor belt 100 and cleans ink and the like adhering to the inner circumferential surface and through-holes 102 of the conveyor belt 100, as well as moisture previously applied. Examples of the cleaning means 207c include rollers or webs having a moisture absorbing function, or air injection means such as an air blower (including a moisture recovery function) that pushes less moisture into the through-holes. In the case of a blade wipe, it is not desirable because it may push moisture into the through-holes 102 and cause the moisture to reach the outer circumferential surface, thereby affecting the conveyance of the recording medium. The roller having a function of absorbing moisture is preferably one having a nonwoven fabric formed on the surface or a porous body such as a sponge, such as a nonwoven fabric roller or a porous roller. Also, the web having a function of absorbing moisture is preferably a nonwoven fabric or a woven fabric capable of absorbing moisture.

[0035] <Inkjet recording device> FIG. 3 is a schematic diagram showing an example of the configuration of an inkjet recording apparatus according to an embodiment of the present invention. The inkjet recording apparatus 300 is a sheet-fed inkjet recording apparatus that produces a recorded matter by forming an ink image on a recording medium 301 using two liquids, a primer and an ink. In Fig. 3, the X direction, Y direction, and Z direction respectively indicate the width direction (total length direction), depth direction, and height direction of the inkjet recording apparatus 300. The recording medium 301 is transported in the A direction.

[0036] The inkjet recording apparatus 300 has a paper feed roller 302, a primer applying device 303, an ink applying device 304, and a heating and drying device 305. The inkjet recording apparatus 300 also includes a recording medium transport device 200 and a paper discharge roller 306, which are disposed opposite the primer applying device 303 and the ink applying device 304. Although not shown in Fig. 3, a fixing device for fixing the ink and a cooling device for cooling the recording medium may be installed after the heating and drying device 305.

[0037] In this embodiment, the recording medium 301 is not particularly limited, and any known recording medium can be used. Examples of the recording medium include a long object wound in a roll, and a sheet cut to a predetermined size. Examples of the material include paper, plastic film, wood board, cardboard, metal film, etc.

[0038] In the inkjet recording apparatus 300 of this embodiment, a recording medium 301 is fed to a paper feed roller 302 in the direction of arrow A, and is transported by a paper discharge roller 306 via a recording medium transport device 200. The paper feed roller 302 and the paper discharge roller 306 are not limited to the configuration shown in FIG. 3 as long as they are capable of transporting the recording medium.

[0039] The inkjet recording apparatus 300 of this embodiment has a primer applying device 303 that applies a primer to a recording medium 301. The primer reduces the fluidity of the ink and / or part of the ink composition on the recording medium 301 by contacting with the ink, and can suppress bleeding and beading during image formation with the ink. Specifically, a reactant (also called an ink viscosity increasing component) contained in the reaction liquid chemically reacts with or physically adsorbs onto a coloring material, resin, or the like that is part of the composition constituting the ink by contacting with the coloring material, resin, or the like that is part of the composition constituting the ink. This causes an increase in the viscosity of the entire ink, or a local increase in viscosity due to aggregation of part of the components constituting the ink, such as the coloring material, and can reduce the fluidity of the ink and / or part of the ink composition.

[0040] The primer applying device 303 may be any device capable of applying a primer onto the recording medium 301, and various conventionally known devices may be appropriately used. Specific examples include a gravure offset roller, an inkjet head, a die coating device (die coater), a blade coating device (blade coater), etc. The primer applying device 303 in Fig. 3 shows the case of an inkjet head.

[0041] The application of the primer by the primer applying device 303 may be performed before or after the application of the ink, as long as it can mix (react) with the ink on the recording medium 301. Preferably, as shown in FIG. 3, a configuration in which the primer is applied before the ink is applied is preferable. By applying the primer before the ink is applied, bleeding, in which adjacent inks applied mix with each other, can be suppressed during image recording by the inkjet method. Furthermore, beading, in which the ink that has landed earlier is attracted to the ink that has landed later, can also be suppressed.

[0042] Hereinafter, each component constituting the primer applied to this embodiment will be described in detail. The primer aggregates the components having anionic groups in the ink (resins, self-dispersing pigments, etc.) by contacting the ink, and contains a reactant. Examples of the reactant include cationic components such as polyvalent metal ions and cationic resins, and organic acids.

[0043] Examples of polyvalent metal ions include Ca. 2+ , Cu 2+ , Ni 2+ , Mg 2+ , Sr 2+ , B.A. 2+ and Zn 2+ Divalent metal ions such as Fe 3+ , Cr 3+ , Y 3+ and Al 3+ In order to incorporate polyvalent metal ions into the primer, a polyvalent metal salt (which may be a hydrate) formed by combining a polyvalent metal ion with an anion can be used. Examples of the anion include Cl. - , Br - , I - , ClO - , ClO2 - , ClO3 - , ClO4 - , NO2 - , NO3 - , SO4 2- , CO32- , HCO3 - , PO4 3- , HPO4 2- , and H2PO4 - Inorganic anions such as HCOO - , (COO - )2, COOH(COO - ), CH3COO - , C2H4(COO - )2, C6H5COO - , C6H4(COO - )2 and CH3SO3 - When a polyvalent metal ion is used as the reactant, the content (mass %) of the polyvalent metal salt in the primer is preferably 1.00 mass % or more and 20.00 mass % or less based on the total mass of the primer.

[0044] The primer containing an organic acid has a buffering ability in the acidic range (less than pH 7.0, preferably from pH 2.0 to pH 5.0), and thereby converts the anionic groups of the components present in the ink into an acid form and causes them to aggregate. Examples of the organic acid include monocarboxylic acids and salts thereof, such as formic acid, acetic acid, propionic acid, butyric acid, benzoic acid, glycolic acid, lactic acid, salicylic acid, pyrrole carboxylic acid, furan carboxylic acid, picolinic acid, nicotinic acid, thiophene carboxylic acid, levulinic acid, and coumaric acid; dicarboxylic acids and salts thereof, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, itaconic acid, sebacic acid, phthalic acid, malic acid, and tartaric acid; tricarboxylic acids and salts thereof, such as citric acid and trimellitic acid; and tetracarboxylic acids and salts thereof, such as pyromellitic acid. The content (mass %) of the organic acid in the primer is preferably 1.00 mass % or more and 50.00 mass % or less based on the total mass of the primer.

[0045] Examples of the cationic resin include resins having a structure of primary to tertiary amines and resins having a structure of quaternary ammonium salts. Specific examples include resins having structures such as vinylamine, allylamine, vinylimidazole, vinylpyridine, dimethylaminoethyl methacrylate, ethyleneimine, and guanidine. In order to increase the solubility in the primer, the cationic resin may be used in combination with an acidic compound or the cationic resin may be subjected to a quaternary treatment. When the cationic resin is used as a reactant, the content (mass%) of the cationic resin in the primer is preferably 1.00 mass% or more and 10.00 mass% or less based on the total mass of the primer.

[0046] As the components other than the reactant, the same aqueous medium and other additives that can be used in the ink, which will be described later, can be used.

[0047] The inkjet recording apparatus 300 of this embodiment has an ink applying device 304 equipped with an inkjet head that applies colored ink onto a recording medium 301 to which a primer has been applied, and forms an ink image, which is an image made of ink, on the recording medium 301. The primer and the ink are mixed on the recording medium 301, and an ink image is formed by the primer and the ink. In this embodiment, an inkjet head is used as the ink application device 304 that applies ink. Examples of inkjet heads include a type that ejects ink by generating film boiling in the ink using an electro-thermal converter to form bubbles, a type that ejects ink using an electro-mechanical converter, and a type that ejects ink using static electricity. In this embodiment, a known inkjet head can be used. Among them, from the viewpoint of high speed and high density printing, one that uses an electro-thermal converter is preferably used. The application (drawing) of ink is performed by receiving an image signal and applying the required amount of ink to each position.

[0048] In this embodiment, the inkjet head is a full line head extending in the Y direction, and the nozzles are arranged in a range covering the width of the image recording area of ​​the largest usable size of recording medium. The inkjet head has an ink ejection surface with nozzles opening on its lower surface (recording medium 301 side), and the ink ejection surface faces the surface of the recording medium 301 with a minute gap (about a few millimeters) therebetween. The amount of ink applied can be expressed by the density value of the image data, the ink thickness, etc., but in this embodiment, the ink application amount (g / m) is calculated by multiplying the mass of each ink dot by the number of ink dots applied and dividing the result by the printing area to obtain the average value. 2 The maximum amount of ink applied in the image area is set to at least 5 mm within the area used as information on the ejection receiving medium from the viewpoint of removing the liquid components in the ink. 2 The amount of ink applied to the above area is shown.

[0049] The ink applicator 304 may have a plurality of inkjet heads for applying each color ink onto the recording medium 301. For example, when forming color images using yellow ink, magenta ink, cyan ink, and black ink, the ink applicator 304 has four inkjet heads for respectively ejecting the above four types of ink onto the recording medium 301. These inkjet heads are arranged in a line in the X direction.

[0050] The ink applicator 304 may also include an inkjet head that ejects a clear ink that does not contain coloring materials or that contains a very low ratio of coloring materials and is substantially transparent. This clear ink can be used to form an ink image together with a primer and color inks. For example, this clear ink can be used to improve the glossiness of an image. In order to give the image a glossy appearance, it is advisable to appropriately adjust the resin components to be mixed and further control the ejection position of the clear ink. It is desirable that this clear ink is on the surface layer side of the color inks in the final recorded product. For this reason, in the movement direction of the recording medium 301 facing the ink applicator 304, the inkjet head for the clear ink can be arranged downstream of the inkjet head for the color inks.

[0051] Hereinafter, each component constituting the ink applied to this embodiment will be described in detail. The coloring material may be a pigment or a dye. The content of the coloring material in the ink is preferably from 0.5% to 15.0% by mass, and more preferably from 1.0% to 10.0% by mass, based on the total mass of the ink.

[0052] Specific examples of pigments include inorganic pigments such as carbon black and titanium oxide; and organic pigments such as azo, phthalocyanine, quinacridone, isoindolinone, imidazolone, diketopyrrolopyrrole, and dioxazine.

[0053] As a pigment dispersion method, resin-dispersed pigments using a resin as a dispersant, self-dispersed pigments in which hydrophilic groups are bonded to the pigment particle surface, etc. Also usable are resin-bonded pigments in which organic groups containing a resin are chemically bonded to the pigment particle surface, and microencapsulated pigments in which the pigment particle surface is coated with a resin or the like.

[0054] As the resin dispersant for dispersing the pigment in the aqueous medium, it is preferable to use one that can disperse the pigment in the aqueous medium by the action of anionic groups. As the resin dispersant, it is preferable to use a resin as described below, and more preferably a water-soluble resin. The content of the pigment (mass%) is preferably 0.3 times or more and 10.0 times or less in terms of the mass ratio to the content of the resin dispersant (pigment / resin dispersant).

[0055] As the self-dispersing pigment, a pigment having an anionic group such as a carboxylic acid group, a sulfonic acid group, or a phosphonic acid group bonded directly or via another atomic group (-R-) to the particle surface of the pigment can be used. The anionic group may be either an acid type or a salt type, and when it is a salt type, it may be either a partially dissociated state or a completely dissociated state. Examples of the cation serving as a counter ion when the anionic group is a salt type include an alkali metal cation; ammonium; organic ammonium; and the like. Specific examples of the other atomic group (-R-) include a linear or branched alkylene group having 1 to 12 carbon atoms; an arylene group such as a phenylene group or a naphthylene group; a carbonyl group; an imino group; an amide group; a sulfonyl group; an ester group; an ether group; and the like. A group consisting of a combination of these groups may also be used.

[0056] It is preferable to use a dye having an anionic group. Specific examples of the dye include azo, triphenylmethane, (aza)phthalocyanine, xanthene, and anthrapyridone dyes.

[0057] The ink may contain a resin. The content (mass %) of the resin in the ink is preferably from 0.1% to 20.0% by mass, and more preferably from 0.5% to 15.0% by mass, based on the total mass of the ink.

[0058] Resins can be added to inks for the following reasons: (i) to stabilize the dispersion state of pigments, i.e., as the above-mentioned resin dispersant or as an auxiliary thereof; and (ii) to improve various properties of the recorded image. Examples of the form of the resin include block copolymers, random copolymers, graft copolymers, and combinations thereof. The resin may be dissolved in an aqueous medium as a water-soluble resin, or may be dispersed in an aqueous medium as resin particles. The resin particles do not need to encapsulate coloring materials.

[0059] In the present invention, a resin is water-soluble when it is neutralized with an alkali equivalent to the acid value and does not form particles whose particle size can be measured by dynamic light scattering. Whether or not a resin is water-soluble can be determined according to the following method. First, a liquid (resin solid content: 10 mass%) containing a resin neutralized with an alkali (sodium hydroxide, potassium hydroxide, etc.) equivalent to the acid value is prepared. Next, the prepared liquid is diluted 10 times (volume basis) with pure water to prepare a sample solution. Then, when the particle size of the resin in the sample solution is measured by dynamic light scattering, if no particles having a particle size are measured, the resin can be determined to be water-soluble. The measurement conditions at this time can be set, for example, as follows: SetZero: 30 seconds, number of measurements: 3 times, measurement time: 180 seconds. As a particle size distribution measurement device, a particle size analyzer using dynamic light scattering (for example, product name "UPA-EX150", manufactured by Nikkiso Co., Ltd.) or the like can be used. Of course, the particle size distribution measurement device and measurement conditions used are not limited to those described above.

[0060] The acid value of the resin is preferably 100 mgKOH / g or more and 250 mgKOH / g or less in the case of a water-soluble resin, and preferably 5 mgKOH / g or more and 100 mgKOH / g or less in the case of resin particles. The weight average molecular weight of the resin is preferably 3,000 or more and 15,000 or less in the case of a water-soluble resin, and preferably 1,000 or more and 2,000,000 or less in the case of resin particles. The volume average particle diameter of the resin particles measured by a dynamic light scattering method (measurement conditions are the same as above) is preferably 100 nm or more and 500 nm or less.

[0061] Examples of the resin include acrylic resins, urethane resins, olefin resins, etc. Among these, acrylic resins and urethane resins are preferred. The acrylic resin preferably has a hydrophilic unit and a hydrophobic unit as constituent units. Among them, a resin having a hydrophilic unit derived from (meth)acrylic acid and a hydrophobic unit derived from at least one of a monomer having an aromatic ring and a (meth)acrylic acid ester monomer is preferred. In particular, a resin having a hydrophilic unit derived from (meth)acrylic acid and a hydrophobic unit derived from at least one of styrene and α-methylstyrene is preferred. These resins are likely to interact with pigments, and therefore can be suitably used as a resin dispersant for dispersing pigments.

[0062] The hydrophilic unit is a unit having a hydrophilic group such as an anionic group. The hydrophilic unit can be formed, for example, by polymerizing a hydrophilic monomer having a hydrophilic group. Specific examples of the hydrophilic monomer having a hydrophilic group include acidic monomers having a carboxylic acid group such as (meth)acrylic acid, itaconic acid, maleic acid, and fumaric acid, and anionic monomers such as anhydrides and salts of these acidic monomers. Examples of cations constituting the salts of acidic monomers include ions of lithium, sodium, potassium, ammonium, and organic ammonium. The hydrophobic unit is a unit not having a hydrophilic group such as an anionic group. The hydrophobic unit can be formed, for example, by polymerizing a hydrophobic monomer not having a hydrophilic group such as an anionic group. Specific examples of the hydrophobic monomer include monomers having an aromatic ring such as styrene, α-methylstyrene, and benzyl (meth)acrylate; and (meth)acrylic acid ester monomers such as methyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

[0063] The urethane resin can be obtained by reacting, for example, polyisocyanate with a polyol. In addition, a chain extender may be further reacted with the urethane resin. The olefin resin can be, for example, polyethylene, polypropylene, etc.

[0064] The ink may contain water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent. As the water, deionized water or ion-exchanged water is preferably used (hereinafter, an ink containing water or an aqueous medium is also referred to as "aqueous ink"). The content (mass%) of water in the aqueous ink is preferably 50.0% by mass or more and 95.0% by mass or less based on the total mass of the ink. The content (mass%) of water-soluble organic solvent in the aqueous ink is preferably 3.0% by mass or more and 50.0% by mass or less based on the total mass of the ink. As the water-soluble organic solvent, any of those usable for inkjet inks, such as alcohols, (poly)alkylene glycols, glycol ethers, nitrogen-containing compounds, and sulfur-containing compounds, may be used.

[0065] Furthermore, in addition to the above components, the ink may contain various additives, such as antifoaming agents, surfactants, pH adjusters, viscosity adjusters, rust inhibitors, preservatives, antifungal agents, antioxidants, and reduction inhibitors, as necessary.

[0066] The inkjet recording apparatus 300 of this embodiment has a heating and drying apparatus 305 at the rear of the ink applying apparatus 304. The heating and drying apparatus 305 heats and dries and solidifies the ink applied to the recording medium 301. By heating and drying the recording medium 301 on which an image has been formed, the liquid components contained in the ink quickly evaporate and disperse, and a film is formed by the polymer particles contained in the ink. In this way, the dried ink is turned into a film on the recording medium 301, and a high-quality image with excellent abrasion resistance can be obtained. Furthermore, by heating and drying the ink, the evaporation of the liquid components in the ink is promoted, and curling and cockling of the recording medium 301 can be suppressed. The heating and drying device 305 may be any device capable of heating and drying, and various conventionally known devices may be appropriately used, but a hot air dryer or a heater is preferable. There is no particular restriction on the type of heater, and it is preferable to appropriately select and apply from known methods, but among them, heating by an electric heating wire or an infrared heater is preferable from the viewpoints of safety and energy efficiency.

[0067] As for the method of heat drying, the surface on which the ink and primer are applied may be heat dried, or the reverse side of the surface on which the ink and primer are applied may be heat dried, or both sides may be heat dried, as shown in Fig. 3. The heat drying temperature is preferably 60°C or higher and 120°C or lower, and more preferably 70°C or higher and 100°C or lower. EXAMPLES

[0068] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited by the following examples unless it exceeds the gist of the present invention. In the following description of the examples, "parts" are based on mass unless otherwise specified. The dimensions of each material used are the values ​​in the manufacturer's catalog.

[0069] <Example 1> The seamless belt used as the inkjet transport belt 100 was produced by the following procedure. A substrate layer 101 made of PET with a thickness of 500 μm was prepared. Through holes 102 with a size of 500 μm were provided in this substrate layer 101 in a staggered arrangement with a hole pitch of 3 mm. Anatase type TiO2 (trade name: ST-01, manufactured by Ishihara Sangyo Kaisha) with a particle diameter of 7 nm was prepared as photocatalyst particles. These photocatalyst particles were mixed with an acrylic binder (trade name: AE120A, manufactured by E-Tech) at 20 mass % to prepare a photocatalyst layer forming composition. The obtained photocatalyst layer forming composition was applied and dried by heating to form a photocatalyst layer 103 with a thickness of 100 μm on the inner peripheral surface of the substrate layer 101, and at the same time, the through holes 102 were filled with the photocatalyst layer to block the through holes. Thereafter, the photocatalyst layer was scraped off from the outer peripheral surface of the substrate layer 101 in order to form a length L of the photocatalyst layer 103 of 100 μm from the inner peripheral surface of the substrate layer 101 toward the outer peripheral surface. Furthermore, a process was performed to make holes through the blocked through holes so that the thickness of the photocatalyst layer on the side of the through holes 102 was 100 μm, thereby obtaining a seamless belt, which was used as the inkjet transport belt 100.

[0070] <Example 2> An inkjet transport belt 100 was obtained in the same manner as in Example 1, except that zinc oxide (ZnO) (product name: FZO-50, manufactured by Ishihara Sangyo Kaisha) having a particle diameter of 21 nm was added to an acrylic binder at 20 mass % and applied as photocatalyst particles.

[0071] <Examples 3 to 6> In the same manner as in Example 1, an inkjet transport belt 100 was obtained.

[0072] <Example 7> An inkjet transport belt 100 was obtained in the same manner as in Example 1, except that a photocatalyst layer 103 was formed on the side surface of the through-hole 102 to a thickness of 100 μm and a length of 250 μm from the inner peripheral surface to the outer peripheral surface.

[0073] <Example 8> An inkjet transport belt 100 was obtained in the same manner as in Example 1, except that a photocatalyst layer 103 was formed on the side surface of the through-hole 102 to a thickness of 100 μm and a length of 400 μm from the inner peripheral surface to the outer peripheral surface.

[0074] <Comparative Example 1> An inkjet transport belt 100 was obtained in the same manner as in Example 1, except that the photocatalyst layer 103 was not formed.

[0075] <Comparative Example 2> A 500μ thick PET substrate layer 101 was prepared. The same photocatalyst layer-forming composition as in Example 1 was applied to the inner circumferential surface of this substrate layer 101, and the composition was dried by heating to form a photocatalyst layer 103 with a thickness of 100 μm. Thereafter, through holes 102 with a size of 500 μm were provided in a staggered arrangement with a hole pitch of 3 mm in the substrate layer 101 on which the photocatalyst layer 103 was formed, thereby obtaining an inkjet conveying belt 100 in which the photocatalyst layer 103 was not formed on the side surface of the through holes 102.

[0076] <Comparative Example 3> A substrate layer 101 made of PET with a thickness of 500 μm was prepared. Through holes 102 with a size of 500 μm were provided in this substrate layer 101 in a staggered arrangement with a hole pitch of 3 mm. Then, the same photocatalyst layer-forming composition as in Example 1 was applied from the inner peripheral surface of the substrate layer 101 with a blade, so that only the through holes 102 were filled with a photocatalyst layer and the through holes were blocked. Then, in order to form a length L of the photocatalyst layer 103 of 100 μm from the inner peripheral surface of the substrate layer 101 toward the outer peripheral surface, the photocatalyst layer was scraped off from the outer peripheral surface of the substrate layer 101. Furthermore, a process was performed to pass holes through the blocked through holes so that the thickness of the photocatalyst layer on the side of the through holes 102 was 100 μm, thereby obtaining an inkjet conveyor belt 100 in which the photocatalyst layer 103 was not formed on the inner peripheral surface of the substrate layer 101.

[0077] <Comparative Example 4> An inkjet transport belt 100 was obtained in the same manner as in Example 1, except that a photocatalyst layer 103 was formed on the side surface of the through-hole 102 to a thickness of 100 μm and a length of 500 μm from the inner peripheral surface to the outer peripheral surface.

[0078] [Table 1]

[0079] Next, in this embodiment, an image was recorded using a recording medium conveying device and a belt cleaning device 200 (FIG. 2) using the inkjet conveying belt 100 prepared above, and further using an inkjet recording device 300 (FIG. 3) including these. The conveying speed was 0.5 m / s, and OK Prince wood-free paper (manufactured by Oji Paper Co., Ltd., basis weight 157 g / m) was used as the recording medium 301. 2 ) was used.

[0080] The primer applied by the primer application device 302 has the following composition and is applied in an amount of 2 g / m 2 The remainder of the ion-exchanged water is the amount such that the total of all components constituting the primer is 100.0 parts by mass. Glutaric acid 21.0 parts by weight Potassium hydroxide 2.0 parts by weight Glycerin 5.0 parts by weight Surfactant (product name: Megafac F444, manufactured by DIC Corporation) 5.0 parts by mass Ion-exchanged water Remainder

[0081] The ink was prepared as follows. (Preparation of Pigment Dispersion) 10 parts of carbon black (product name: Monac 1100, manufactured by Cabot), 15 parts of resin aqueous solution (styrene-ethyl acrylate-acrylic acid copolymer, acid value 150, weight average molecular weight (Mw) 8,000, aqueous solution containing 20.0% resin by mass neutralized with potassium hydroxide aqueous solution), and 75 parts of pure water were mixed and charged into a batch-type vertical sand mill (manufactured by Imex), 200 parts of zirconia beads with a diameter of 0.3 mm were added, and dispersion treatment was carried out for 5 hours while cooling with water. This dispersion was centrifuged to remove coarse particles, and a black pigment dispersion with a pigment content of 10.0% by mass was obtained.

[0082] (Preparation of Resin Particle Dispersion) 20 parts of ethyl methacrylate, 3 parts of 2,2'-azobis-(2-methylbutyronitrile), and 2 parts of n-hexadecane were mixed and stirred for 0.5 hours. This mixture was added dropwise to 75 parts of an 8% aqueous solution of styrene-butyl acrylate-acrylic acid copolymer (acid value: 130 mgKOH / g, weight average molecular weight (Mw): 7,000) and stirred for 0.5 hours. Next, ultrasonic waves were irradiated for 3 hours using an ultrasonic irradiation machine. Subsequently, a polymerization reaction was carried out at 80°C for 4 hours under a nitrogen atmosphere, and after cooling to room temperature, filtration was carried out to prepare a resin particle dispersion having a resin content of 25.0% by mass.

[0083] (Ink Preparation) The pigment dispersion and resin particle dispersion obtained above were mixed with the following components in the following compositions: The remaining amount of ion-exchanged water is the amount that makes the total of all the components constituting the ink 100.0 parts by mass. Pigment dispersion (colorant content is 10.0% by mass) 40.0 parts by mass ·Resin particle dispersion 20.0 parts by mass Glycerin 7.0 parts by weight Polyethylene glycol (number average molecular weight (Mn): 1,000) 3.0 parts by mass Surfactant Acetylenol E100 (Kawaken Fine Chemicals Co., Ltd.) 0.5 parts by mass Ion-exchanged water Remainder

[0084] This was thoroughly stirred to disperse, and then pressure filtered through a microfilter (manufactured by Fujifilm Corporation) with a pore size of 3.0 μm to prepare a black ink.

[0085] The ink application means 303 is an inkjet head that uses an electrothermal conversion element to eject ink on demand, and the amount of ink applied is 10 g / m 2 It was decided.

[0086] Next, a hot air dryer was used as the heating and drying device 305 for heating and drying the ink, and the surface temperature of the recording medium 301 was set to 80°C. Further, the recording medium conveying device and belt cleaning device 200 arranged opposite the primer applying device 303 and the ink applying device 304 had a negative pressure of 500 Pa to suck and adsorb the recording medium 301 . Furthermore, the combination of the configurations of the light irradiation means 207a, the moisture providing means 207b, and the cleaning means 207c of the belt cleaning device 207 is shown in Table 2 below, and cleaning was performed constantly during printing. In order to evaluate the cleaning property and the suction transport property of the inkjet transport belt 100 under the above printing conditions, 10,000 solid images with a margin of 1 cm of an A4 size picture frame were printed continuously.

[0087] [Table 2]

[0088] [evaluation] Under the above-mentioned conditions, the inkjet transport belt 100 was evaluated by the following evaluation method. The evaluation results are shown in Table 3. In the following evaluation method, the evaluation criteria A to B for each evaluation item were defined as preferable levels, and C was defined as unacceptable level.

[0089] <Cleaning ability> The amount of coloring material, paper powder, etc. attached to the inner circumferential surface of the inkjet conveyor belt 100 and the side surface of the through-holes 102 was observed. A small amount of coloring material, paper powder, etc. attached is preferable, and indicates high cleanability. The evaluation criteria are as follows. A: Almost no adhesion of coloring material or paper powder was observed. B: A small amount of coloring material was observed, but no adhesion of paper powder or the like was observed. C: Significant adhesion of coloring material and paper powder was observed.

[0090] <Suction transportability> The change in the suction conveying property of the inkjet conveying belt 100 for the recording medium was observed. If the inner peripheral surface of the inkjet conveying belt 100 and the side surface of the through hole 102 are sufficiently cleaned, it means that the suction conveying property is maintained. The evaluation criteria are as follows. A: Even after printing 10,000 sheets, no change was observed in the suction transport properties of the recording medium during printing. B: During printing of 5,000 or more sheets but less than 10,000 sheets, a part of the recording medium was lifted, causing image misalignment. C: When printing less than 5,000 sheets, a part of the recording medium floated, causing image misalignment, or a part of the recording medium expanded due to the influence of moisture.

[0091] [Table 3] [Explanation of symbols]

[0092] 100 Seamless belt (inkjet conveyor belt) 101 Base material layer 102 Through hole 103 Photocatalyst layer 200 Recording medium transport device and belt cleaning device 204 Carrying Plate 206 Suction part 207 Belt cleaning device 207a Light irradiation means 207b Moisture supplying means 207c Cleaning methods 300 Inkjet recording device 301 Recording media 302 Paper feed roller 303 Primer application device 304 Ink application device

Claims

1. A seamless belt having a base layer having a plurality of through holes and a photocatalyst layer, The photocatalyst layer is provided on an inner circumferential surface of the base layer and on a side surface of the through hole, The photocatalyst layer on the side surface of the through hole is provided in an area starting from the inner circumferential surface on which the photocatalyst layer is provided but not reaching the outer circumferential surface.

2. 2. The seamless belt according to claim 1, wherein, when a thickness of the base material layer is T, a length L (distance from an inner peripheral surface to an outer peripheral surface) of the photocatalyst layer provided on a side surface of the through hole is 0.2T / or more and 0.8T / or less.

3. A transport belt for inkjet printing, comprising the seamless belt according to claim 1 or 2.

4. 4. A recording medium conveying device including the inkjet conveying belt according to claim 3, a conveying plate having an opening in contact with an inner circumferential surface of the conveying belt, and a suction unit that sucks air from the conveying plate to adsorb a recording medium to the conveying belt, a belt cleaning device for cleaning the inkjet transport belt, The belt cleaning device is a recording medium transport device comprising: a light irradiation means for irradiating active light to activate the photocatalyst layer; a moisture addition means for adding moisture to the inner surface of the inkjet transport belt; and a cleaning means for cleaning the inner surface of the inkjet transport belt to which moisture has been added by the moisture addition means.

5. The recording medium transport device according to claim 4 , wherein the cleaning means is a nonwoven fabric roller, a porous roller, or an air blower.

6. 5. An inkjet recording apparatus comprising: the recording medium transport device according to claim 4; and an image forming device that forms an image on the recording medium.

Images