Cleaning method, image formation method, cleaning device and image formation device

Abstract

To provide a conveyance belt cleaning method that can suppress self-flocculation of a flocculant added to a cleaning fluid, and further, can suppress deterioration of a conveyance belt due to pollutants.SOLUTION: A conveyance belt cleaning method for applying a color ink containing a black ink to a recording medium conveyed on a conveyance belt to form an image has steps of: applying a cleaning fluid containing an inorganic flocculant to the conveyance belt after the recording medium has moved to other component; and recovering the applied cleaning fluid. The cleaning fluid to be applied has a ratio (λcleaningfluid / λink) of an absorbance (λcleaningfluid) of a filtrate, which is obtained by filtration of the recovered cleaning fluid, at a maximum absorption wavelength within a wavelength range of 350 nm or more and 800 nm or less to an absorbance (λink) of the black ink, where a concentration is adjusted so that a concentration of a coloring agent becomes 0.5 mass%, at the maximum absorption wavelength is 0.01% or more and 50% or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a cleaning method, an image forming method, a cleaning device, and an image forming device. [Background technology]

[0002] An image forming apparatus that forms an image using ink has a conveyor belt that conveys a recording medium, and an image forming section that applies ink to the recording medium conveyed on the conveyor belt. During image formation, the conveyor belt becomes contaminated by ink, paper scraps and lint that are cut off from the recording medium, dust in the air, and the like. In order to remove these contaminants, the conveyor belt is periodically cleaned.

[0003] For example, Patent Document 1 describes a printing system having a cleaning unit that cleans a conveying belt by applying a cleaning liquid (washing liquid), a separation unit that applies a coagulant to the cleaning liquid after cleaning and separates the agglomerates formed by the coagulant from the cleaning liquid, and a storage unit that stores the cleaning liquid from which the agglomerates have been removed for reuse. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-083155 Summary of the Invention [Problem to be solved by the invention]

[0005] As described in Patent Document 1, a method for cleaning a conveyor belt of an image forming apparatus with a cleaning liquid is known. Patent Document 1 also describes removing contaminants from the cleaning liquid after cleaning and reusing the cleaning liquid after removal. To remove contaminants from the cleaning liquid after cleaning, a method is used in which a flocculant is added to flocculate the contaminants and the flocculates are removed using a filter or the like.

[0006] However, according to the findings of the present inventors, if the concentration of the coagulant in the cleaning solution is increased in order to ensure the removal of contaminants, self-aggregation of the coagulant occurs, which in turn reduces the efficiency of removing contaminants from the cleaning solution. On the other hand, if the amount of coagulant added is reduced in order to prevent self-aggregation, the contaminants do not aggregate sufficiently, and the efficiency of removing contaminants does not increase. If a cleaning solution that cannot sufficiently remove such contaminants is reused, the conveyor belt will deteriorate due to the contaminants that have not been completely removed.

[0007] The present invention has been made in consideration of the above circumstances, and has an object to provide a method for cleaning a conveyor belt, which can suppress self-aggregation of a coagulant added to a cleaning liquid and also suppress deterioration of the conveyor belt due to contaminants, an image forming method using the cleaning method, a cleaning device capable of performing the cleaning method, and an image forming device that performs the cleaning method. [Means for solving the problem]

[0008] One aspect of the present invention for solving the above-mentioned problems relates to a method for cleaning a conveyor belt as set forth in the following items [1] to

[10] . [1] A method for cleaning a conveyor belt for forming an image by applying one or more types of color inks including a black ink to a recording medium conveyed on the conveyor belt, comprising the steps of: applying a cleaning liquid containing an inorganic flocculant to the conveyor belt after the recording medium has been moved to another member; and recovering the applied cleaning liquid. The applied cleaning solution is a cleaning solution having a colorant concentration adjusted to 0.5 mass % by adding ion-exchanged water, and has an absorbance (λ ) of the black ink at a maximum absorbance wavelength in the wavelength range of 350 nm to 800 nm. インク ) at the maximum absorption wavelength of the filtrate obtained by filtering the recovered washing solution. 洗浄液 ) ratio (λ 洗浄液 / λ インク ) is 0.01% or more and 50% or less, Cleaning method: [2] The ratio (λ洗浄液 / λ インク ) is 0.1% or more and 30% or less, [1] The cleaning method described above. [3] The cleaning solution contains an inorganic flocculant selected from the group consisting of polyaluminum chloride, aluminum sulfate, ferric chloride, and ferrous sulfate; The cleaning method described in [1] or [2]. [4] The amount of the inorganic flocculant is 0.01% by mass or more and 5% by mass or less based on the total mass of the cleaning solution. The cleaning method according to any one of [1] to [3]. [5] The color ink is an ink containing a colorant selected from the group consisting of reactive dyes, disperse dyes, acid dyes, and pigments. The cleaning method according to any one of [1] to [4]. [6] The cleaning solution contains an organic polymer. The cleaning method according to any one of [1] to [5]. [7] The organic polymer is polyacrylamide or sodium polyacrylate; [6] A cleaning method according to the present invention. [8] The cleaning solution has a pH of 4 or more and 6 or less. The cleaning method according to any one of [1] to [7]. [9] filtering the recovered cleaning solution and adjusting the concentration of the filtered cleaning solution; applying the cleaning liquid having the adjusted concentration to the conveyor belt; having The cleaning method according to any one of [1] to [8].

[10] The recording medium is a fabric. The cleaning method according to any one of [1] to [9].

[0009] Another aspect of the present invention for solving the above problems relates to an image forming method as described below in

[11] .

[11] conveying a recording medium on a conveyor belt; applying one or more color inks, including a black ink, to the recording medium to form an image; and cleaning the conveyor belt after the recording medium has been moved to another member by the cleaning method according to any one of [1] to

[10] . Image forming method.

[0010] Another aspect of the present invention for solving the above problem relates to a cleaning apparatus as described below in

[12] .

[12] A conveyor belt for conveying a recording medium; an image forming unit that applies one or more types of color inks, including a black ink, to the recording medium transported on the transport belt to form an image, the image forming unit comprising: A liquid applying unit that applies a cleaning liquid to the conveyor belt; a liquid recovery unit that recovers the applied cleaning liquid; The concentration of the collected cleaning solution was adjusted by adding ion-exchanged water to a colorant concentration of 0.5 mass %, and the absorbance (λ インク ) at the maximum absorption wavelength of the filtrate obtained by filtering the recovered cleaning solution (λ 洗浄液 ) ratio (λ 洗浄液 / λ インク A concentration adjusting unit adjusts the concentration of the liquid to be 0.01% or more and 50% or less. Cleaning equipment.

[0011] Another aspect of the present invention for solving the above problems relates to an image forming apparatus according to the following items

[13] and

[14] .

[13] A conveyor belt for conveying a recording medium; an image forming unit that applies one or more types of color ink, including black ink, to the recording medium transported on the transport belt to form an image; and a cleaning device according to

[12] , which cleans the conveyor belt after the recording medium has been moved to another member. Image forming device.

[14] A concentration meter for measuring the concentration of the cleaning liquid collected by the liquid collection unit.

[13] The image forming apparatus according to claim 1. Effect of the Invention

[0012] According to the present invention, there are provided a method for cleaning a conveyor belt, which can suppress self-aggregation of a coagulant added to a cleaning liquid and also suppress deterioration of the conveyor belt due to contaminants, an image forming method using the cleaning method, a cleaning device capable of performing the cleaning method, and an image forming device that performs the cleaning method. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a flow chart showing the steps of an image forming method using the image forming apparatus. [Diagram 3] FIG. 3 is a flow chart showing sub-steps of a cleaning process using a cleaning device, which is one step of an image forming method. [Figure 4] FIG. 4 is a schematic diagram of an image forming apparatus according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] [Image forming device and cleaning device] FIG. 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention.

[0015] As shown in FIG. 1, the image forming apparatus 100 includes a conveyor belt 110, an image forming section 120, and a cleaning device 200 that cleans the conveyor belt 110.

[0016] The conveyor belt 110 is an endless belt member stretched around rotatable pulleys 112a and 112b. The conveyor belt 110 is rotated in the conveying direction X of the recording medium 130 by the rotation of the pulleys 112a and 112b. A rotatable feed roller 114 is disposed at a position facing the pulley 112a on the upstream side in the conveying direction X. The feed roller 114, together with the pulley 112a, holds the conveyor belt 110 and the recording medium 130 between them, and rotates to feed the recording medium 130 onto the conveyor belt 110.

[0017] In this embodiment, the recording medium 130 is a fabric on which an image is formed using a water-based ink. A grounding agent is applied to the surface of the conveyor belt 110 on the side to which the fabric is supplied, to fix the fabric to the belt surface and stabilize the conveyance. The type of recording medium 130 is not particularly limited, and may be paper or a resin film. As the grounding agent, a known grounding agent may be used, such as a rubber-based grounding agent mainly composed of natural rubber and synthetic rubber, an acrylic-based grounding agent mainly composed of acrylic resin, or a silicon-based grounding agent mainly composed of silicon resin.

[0018] The image forming unit 120 has an inkjet head 122 that ejects water-based ink by an inkjet method. The inkjet head 122 has a plurality of nozzles for ejecting ink droplets of color inks of Y (yellow), M (magenta), C (cyan), and K (black) onto the recording medium 130. For example, the inkjet head 122 is configured so that a plurality of different color inks are each supplied to a specific nozzle. Alternatively, the image forming unit 120 has a plurality of inkjet heads 122 corresponding to these colors. The one or more inkjet heads 122 may be arranged so as to be freely scanned in a direction transverse to the transport direction X of the recording medium 130 on which an image is to be formed.

[0019] The inkjet head 122 is supplied with ink from an ink tank 124 via an ink pipe 126 connected to the ink tank 124 and a valve 128 .

[0020] In this embodiment, the ink is an aqueous inkjet ink containing a colorant, an organic solvent, and water. The ink includes color inks of Y (yellow), M (magenta), C (cyan), and K (black) that have different types of dyes. The type of ink and the type of colorant contained in the ink are not limited to these. For example, the ink may be a solvent ink that contains an organic solvent but does not substantially contain water, or a curable ink that contains a curable composition that polymerizes by irradiation with actinic rays (such as ultraviolet rays or electron beams) as a liquid component. The type of colorant may be a dye such as a reactive dye, a disperse dye, or an acid dye, or a pigment.

[0021] The inkjet head 122 ejects and deposits ink droplets of the above-mentioned color inks onto the recording medium 130, forming an image using these inks on the recording medium 130. Note that the inkjet head 122 may eject and deposit a clear ink onto the recording medium 130 in addition to these color inks.

[0022] The cleaning device 200 includes a liquid application section 210 that applies a cleaning liquid to the conveyor belt 110, a liquid recovery section 220 that recovers the applied cleaning liquid, a concentration adjustment section 230 that adjusts the concentration of the recovered cleaning liquid, and a liquid supply section 240 that supplies the cleaning liquid whose concentration has been adjusted to the liquid application section 210. The cleaning device 200 recovers the cleaning liquid used to clean the conveyor belt 110 in the liquid application section 210 in the liquid recovery section 220 to remove contaminants, and then resupplies the cleaning liquid from the liquid supply section 240 to the liquid application section 210. By reusing the cleaning liquid in this way, wastewater treatment of the cleaning liquid is not required, making it possible to cut costs and reduce environmental pollution.

[0023] The liquid applying unit 210 has a nozzle 211 that sprays the cleaning liquid 300 onto the conveyor belt 110, a receiving tank 212 that receives the cleaning liquid sprayed from the nozzle 211, a rotatable cleaning brush 214, and a scraper 219. The receiving tank 212 is a liquid tank that stores the cleaning liquid 300 that has been sprayed from the nozzle 211 and used for cleaning and that has dripped from the cleaning brush 214 or the scraper 219, and is disposed at a position where the cleaning brush 214 does not come into contact with the cleaning liquid 300 in the receiving tank 212. The cleaning brush 214 has a cylindrical shaft portion 214a that can be rotated by a rotation mechanism (not shown), and a brush portion 214b that is composed of a large number of bristles that are radially arranged from the outer periphery of the shaft portion 214a. The cleaning brush 214 can be moved between a position where the brush portion 214b contacts the conveyor belt 110 and a position where the brush portion 214b does not contact the conveyor belt 110 by a lifting mechanism (not shown). The scraper 219 is a flat plate-shaped member made of an elastic material such as rubber or a synthetic resin such as polyethylene terephthalate (PET).

[0024] When cleaning the conveyor belt 110, the nozzle 211 sprays the cleaning liquid 300 onto the surface of the conveyor belt 110. By spraying the cleaning liquid 300, contaminants such as ink attached to the surface of the conveyor belt 110, paper scraps and lint removed from the recording medium, and dust in the air are removed from the conveyor belt 110. At this time, the cleaning brush 214 is moved by the lifting mechanism to a position where the brush part 214b contacts the conveyor belt 110. Then, when the shaft part 214a is rotated by the rotation mechanism, the brush part 214b rubs the surface of the conveyor belt 110 to which the cleaning liquid 300 is attached, thereby removing the contaminants. Furthermore, the scraper 219 removes the contaminants and the cleaning liquid 300 remaining on the surface of the conveyor belt 110 from the conveyor belt 110. In this way, the contaminants are removed from the conveyor belt 110 by the nozzle 211, the cleaning brush 214, and the scraper 219. The removed contaminants are collected in a receiving tank 212 .

[0025] The cleaning liquid 300 is a water-based liquid that contains a flocculant that reacts with at least a portion of the contaminants (for example, a colorant such as a dye or pigment) to flocculate them, and water as a medium.

[0026] The flocculant is preferably an inorganic flocculant. Examples of inorganic flocculants include polyaluminum chloride, aluminum sulfate, ferric chloride, ferrous sulfate, and polysilica iron. Of these, polyaluminum chloride, aluminum sulfate, ferric chloride, and ferrous sulfate are preferred because of their high flocculation action, and ferric chloride is more preferred. It was not clear whether these flocculants are effective in flocculating contaminants such as colorants (dyes, etc.) contained in the ink, but according to the findings of the present inventors, these flocculants are also effective in flocculating the above-mentioned colorants. The content of the inorganic flocculant can be, for example, 0.1% by mass or more and 5% by mass or less with respect to the total mass of the cleaning liquid, and is preferably 0.5% by mass or more and 4% by mass or less. However, the content of the inorganic flocculant can be changed by adjusting the concentration as described below.

[0027] The cleaning liquid 300 may contain an organic polymer. By using an inorganic flocculant and an organic polymer in combination, the flocculation of contaminants can be performed more efficiently. The organic polymer may be an anionic polymer, a cationic polymer, a nonionic polymer, or an amphoteric polymer. Examples of anionic polymers include polyacrylamide and sodium polyacrylate. Examples of cationic polymers include polyacrylamide, polyacrylic acid ester, polymethacrylic acid ester, polyamine, and polydicyandiamide. Examples of nonionic polymers include polyacrylamide and polyethylene oxide. Examples of amphoteric polymers include dimethylaminoethyl acrylate. Of these, polyacrylamide and sodium polyacrylate are preferred because of their high flocculation effect, and it is more preferred that the polyacrylamide is an anionic polymer. The content of the organic polymer can be, for example, 0.01% by mass or more and 2% by mass or less with respect to the amount of the flocculant added, and is preferably 0.05% by mass or more and 1% by mass or less. However, the content of the organic polymer may be changed by adjusting the concentration as described later.

[0028] The cleaning liquid 300 preferably has a pH value of 4 or more and 6 or less. By making the cleaning liquid 300 acidic, it is possible to make it more difficult for the inorganic flocculant to self-aggregate.

[0029] The liquid recovery section 220 has a recovery tank 222 that stores the recovered cleaning liquid 300, and a recovery flow path 224 for sending the cleaning liquid 300 in the receiving tank 212 to the recovery tank 222 to recover it. A recovery pump 226 is installed in the recovery flow path 224 to send the cleaning liquid 300 from the receiving tank 212 to the recovery tank 222. A recovery filter 228 is installed at an inlet of the recovery tank 222 through which the cleaning liquid 300 flows.

[0030] After or during cleaning of the conveyor belt 110, the liquid recovery unit 220 recovers a portion of the cleaning liquid 300 in the receiving tank 212 into the recovery tank 222 through the recovery flow path 224. At this time, the recovery filter 228 filters the cleaning liquid 300 in the recovery flow path 224 to remove aggregates of contaminants aggregated by the coagulant.

[0031] The recovery tank 222 may be configured to agitate the cleaning liquid 300 in the recovery tank 222 with a rotating agitating blade (not shown) or the like to make the concentration uniform.

[0032] The concentration adjustment unit 230 has a concentration meter 231 that measures the concentration of the cleaning liquid 300 in the collection tank 222, and an adjustment liquid tank 232 that stores an adjustment liquid 310 that is a liquid with a low concentration of aggregating agent. The concentration adjustment unit 230 also has an adjustment flow path 234a that sends the adjustment liquid 310 in the adjustment liquid tank 232 to the inside of the collection tank 222. The concentration adjustment unit 230 also has an adjustment flow path 234b that communicates with the ink tank 124 and the collection tank 222 and sends color ink (e.g., black ink) in the ink tank 124 to the inside of the collection tank 222. An adjustment pump 236a that sends the adjustment liquid 310 from the adjustment liquid tank 232 to the collection tank 222, and an adjustment valve 238a are installed in the adjustment flow path 234a. An adjustment pump 236b for sending ink from the ink tank 124 to the ink collection tank 222, and an adjustment valve 238b are installed in the adjustment flow path 234b.

[0033] The concentration measuring device 231 is, for example, a spectrophotometer that measures the absorbance at each wavelength of the cleaning liquid 300 in the collection tank 222 or the cleaning liquid 300 extracted from the collection tank 222 .

[0034] The concentration adjustment unit 230 controls the driving of the adjustment pumps 236a and 236b and the opening and closing of the adjustment valves 238a and 238b in accordance with the concentration of the cleaning liquid 300 measured by the concentration measuring device 231. In this way, the adjustment liquid 310 in the adjustment liquid tank 232 or the ink in the ink tank 124 is added to the cleaning liquid 300 in the recovery tank 222, thereby adjusting the concentration of the cleaning liquid 300 to a predetermined range.

[0035] For example, when a fabric is used as the recording medium 130, a grounding agent may be applied to the surface of the conveyor belt 110 in order to stably convey the fabric. If the cleaning liquid 300 containing a large amount of dye, which is a contaminant, is applied to such a conveyor belt 110, the grounding agent is likely to deteriorate due to the dye. In order to suppress deterioration of the conveyor belt 110 due to the contaminants in the cleaning liquid 300 when the cleaning liquid 300 is reused to clean the conveyor belt 110, it is considered desirable to more reliably remove the contaminants such as dye from the cleaning liquid 300. In order to increase the efficiency of removing the contaminants, it is sufficient to increase the concentration of the flocculant in the cleaning liquid 300 to make it easier to flocculate the contaminants, and to increase the efficiency of removing the contaminants (flocculants) by the collection filter 228.

[0036] However, according to the findings of the present inventors, increasing the concentration of the flocculant in an attempt to increase the efficiency of removing contaminants from the cleaning liquid 300 actually decreases the efficiency of removing contaminants from the cleaning liquid 300. This is believed to be because the flocculant self-aggregates and is unable to sufficiently flocculate the contaminants.

[0037] Based on the above findings, the inventors have investigated methods for increasing the efficiency of removing contaminants from the cleaning solution 300, and have found that the efficiency of removing contaminants is actually increased by intentionally leaving a small amount of contaminants in the cleaning solution 300. In other words, the efficiency of removing contaminants can be increased by increasing the concentration of the coagulant in the cleaning solution 300 to a level that allows the contaminants to be sufficiently coagulated and removed, but not so high that the contaminants are completely coagulated.

[0038] Specifically, the concentration of the colorant in the black ink among the color inks discharged from the inkjet head 122 is adjusted to 0.5 mass % by adding ion-exchanged water, and the absorbance of the black ink thus adjusted at the maximum absorption wavelength in the wavelength range of 350 nm to 800 nm is expressed as λ インクOn the other hand, the absorbance of the cleaning liquid 300 in the recovery tank 222 (which is also the filtrate filtered by the recovery filter 228) at the same wavelength as the maximum absorption wavelength set for the black ink is set as λ 洗浄液 In addition, λ 洗浄液 is measured by the concentration measuring device 231. In the cleaning device 200 based on the above knowledge, the concentration adjusting unit 230 adjusts the ratio of the absorbance (λ 洗浄液 / λ インク The concentration of the cleaning liquid 300 in the recovery tank 222 is adjusted so that the concentration of the cleaning liquid 300 is in the range of 0.01% to 50%.

[0039] The ink applied to the recording medium 130 is often a mixture of multiple colors (four colors: YMCK in this embodiment), and the colorant that adheres to the conveyor belt 110 and is removed by the cleaning brush 214 and mixed into the cleaning liquid 300 is often a mixture of the colorants contained in these inks. Therefore, the color of the cleaning liquid 300 mixed with the mixture of these colorants is close to black. For this reason, the black ink ejected from the inkjet head 122 is diluted to a colorant concentration of 0.5 mass %, and the colorant concentration (absorbance λ インク The amount of colorant contained in the cleaning liquid 300 as a contaminant is determined by the following formula:

[0040] In the cleaning liquid 300, the colorant as a contaminant is agglutinated and removed. 洗浄液 ) is expressed as λ インク At this time, the ratio (λ 洗浄液 / λ インク When the concentration of the flocculant in the cleaning solution 300 is reduced to such an extent that the ratio (λ) is 0.01% or more, the flocculant is less likely to self-aggregate, and the efficiency of removing contaminants from the cleaning solution 300 is increased. 洗浄液 / λ インク When the concentration of the flocculant in the cleaning liquid 300 is increased to such an extent that the ratio (λ) is 50% or less, the flocculant sufficiently flocculates the contaminants, thereby increasing the efficiency of removing the contaminants from the cleaning liquid 300.洗浄液 / λ インク ) is preferably 0.1% or more and 30% or less, and more preferably 0.1% or more and 10% or less.

[0041] In addition, the absorbance λ 洗浄液 can vary depending on the type and combination of aggregating agents, and can also vary depending on the concentration of the colorant in the ink used to form the image. 洗浄液 The concentration of the flocculant required to achieve this is not necessarily a constant concentration. 洗浄液 and the absorbance λ measured from the ink インク Since the concentration of the cleaning liquid 300 is adjusted by the above, it is possible to increase the efficiency of removing contaminants from the cleaning liquid 300, without being limited to the above-mentioned changes.

[0042] In this embodiment, the concentration measuring device 231 measures the absorbance λ of the cleaning liquid 300 stored in the collection tank 222 after the contaminants have been removed by the collection filter 228. 回収液 Then, measure λ 回収液 and λ インク Ratio of (λ 回収液 / λ インク ) is higher than the above range (higher than 50%), the concentration adjuster 230 determines that the concentration of the flocculant in the cleaning liquid 300 is too low. Then, the adjustment pump 236a is driven, the adjustment valve 238a is opened, and the adjustment liquid 310 with a high concentration of flocculant stored in the adjustment liquid tank 232 is added to the recovery tank 222. This allows the contaminants to be sufficiently flocculated in the cleaning liquid 300 after the next cleaning, thereby increasing the efficiency of removing the contaminants. On the other hand, λ 回収液 and λ インク Ratio of (λ 回収液 / λ インク) is lower than the above range (lower than 0.01%), the concentration adjustment unit 230 determines that the concentration of the flocculant in the cleaning liquid 300 is excessive. Then, the adjustment pump 236b is driven, the adjustment valve 238b is opened, and ink is added from the ink tank 124 to the recovery tank 222. This increases the concentration of the colorant in the cleaning liquid, and the colorant and the flocculant react with each other to reduce the concentration of the flocculant. In this way, self-aggregation of the flocculant is suppressed, and the efficiency of removing contaminants from the cleaning liquid 300 after the next cleaning can be increased.

[0043] In this manner, the concentration adjusting unit 230 adjusts the concentration of the cleaning liquid 300 in the collection tank 222 by λ 回収液 / λ インク is adjusted to be within the above range.

[0044] The liquid supply unit 240 has a supply flow path 244 for supplying the cleaning liquid 300, the concentration of which has been adjusted in the collection tank 222, to the nozzle 211. A supply pump 246 for sending the cleaning liquid 300 from the collection tank 222 to the nozzle 211, and a supply filter 248 are installed in the supply flow path 244.

[0045] The liquid supply unit 240 supplies a portion of the cleaning liquid 300, the concentration of which has been adjusted by the concentration adjustment unit 230, to the nozzle 211 through the supply flow path 244. At this time, the supply filter 248 filters the cleaning liquid 300 in the supply flow path 244 to remove unnecessary substances. Note that since aggregates of the colorant that affect the absorbance are removed by the recovery filter 228 of the recovery flow path 224, the λ 回収液 is basically unchanged.

[0046] In this way, λ 回収液 and λ インク Ratio of (λ 回収液 / λ インク By reusing the cleaning liquid whose concentration has been adjusted so that the concentration of the cleaning liquid is within a predetermined range and using it to clean the conveyor belt 110, it is possible to efficiently remove contaminants.

[0047] [Image forming method and cleaning method] Fig. 2 is a flowchart showing each step of an image forming method using the above-mentioned image forming apparatus 100. Fig. 3 is a flowchart showing each sub-step of a cleaning process using the above-mentioned cleaning apparatus 200, which is one step of the image forming method.

[0048] As shown in FIG. 2, the image forming apparatus 100 first conveys the recording medium 130 onto the conveyor belt 110 (step S110).

[0049] Then, ink is applied to the conveyed recording medium 130 to form an image (step S120). Specifically, ink of each color of YMCK is applied to a predetermined position on the recording medium 130 while scanning the inkjet head 122 in a direction transverse to the conveyance direction X of the recording medium 130 as necessary.

[0050] Then, after the recording medium 130 is moved from the conveyor belt 110 to another member, the conveyor belt 110 is cleaned (step S130).

[0051] As shown in FIG. 3, in the cleaning step (step S130), the cleaning device 200 first applies a cleaning liquid to the conveyor belt 110 to clean the conveyor belt 110 (step S210). Specifically, the liquid applying unit 210 sprays the cleaning liquid 300 from the nozzle 211 onto the surface of the conveyor belt 110. The liquid applying unit 210 also moves the cleaning brush 214 to a position where the brush part 214b contacts the conveyor belt 110 by the lifting mechanism. Then, the liquid applying unit 210 rotates the shaft part 214a of the cleaning brush 214 by the rotation mechanism, and causes the brush part 214b to rub the surface of the conveyor belt 110. The liquid applying unit 210 removes contaminants from the conveyor belt 110 by the spraying of the cleaning liquid 300 from the nozzle 211, the rubbing by the brush part 214b of the cleaning brush 214, and the contact of the scraper 219. The removed contaminants drip into the receiving tank 212 along with the cleaning fluid 300 .

[0052] When the cleaning liquid used by the liquid deposition unit 210 is reused (step S220, YES), the liquid recovery unit 220 removes aggregated contaminants from the cleaning liquid 300 in the receiving tank 212 and recovers it in the recovery tank 222 (step S230). Specifically, the liquid recovery unit 220 drives the recovery pump 226 to circulate the cleaning liquid 300 in the receiving tank 212 through the recovery flow path 224, removes aggregates of contaminants using the recovery filter 228, and stores the resultant in the recovery tank 222.

[0053] Next, the concentration adjustment unit 230 adjusts the concentration of the cleaning liquid 300 in the collection tank 222 (step S240). Specifically, the concentration adjustment unit 230 measures the concentration (absorbance for each wavelength) of the cleaning liquid 300 in the collection tank 222 using the concentration measurement device 231. Then, when the concentration of the aggregating agent in the cleaning liquid 300 (absorbance at the maximum absorption wavelength of the black ink) falls within a predetermined range (λ 洗浄液 / λ インク When the concentration of the flocculant in the cleaning liquid 300 is lower than the predetermined range (the range is 0.01% or more and 50% or less), the concentration adjustment unit 230 adds an adjusting liquid 310 having a high concentration of the flocculant to the collection tank 222. When the concentration of the flocculant in the cleaning liquid 300 is lower than the predetermined range, the concentration adjustment unit 230 adds a color ink to the collection tank 222. In this way, the concentration adjustment unit 230 adjusts the concentration of the cleaning liquid 300 in the collection tank 222 based on λ 洗浄液 / λ インク is adjusted to a range of 0.01% or more and 50% or less.

[0054] Then, the liquid supply unit 240 supplies the cleaning liquid 300, the concentration of which has been adjusted by the concentration adjustment unit 230, to the nozzle 211 (step S250). Specifically, the liquid supply unit 240 drives the supply pump 246 to circulate the cleaning liquid 300 in the collection tank 222 through the supply flow path 244, removes unnecessary substances using the supply filter 248, and supplies the cleaning liquid 300 to the nozzle 211.

[0055] Then, the liquid deposition unit 210 deposits (sprays) the supplied cleaning liquid 300 from the nozzles 211 onto the conveyor belt 110 to clean the conveyor belt 110 (step S210).

[0056] When the cleaning liquid used by the liquid deposition unit 210 is not reused (step S220, NO), such as when the cleaning step is completed, these steps are not performed.

[0057] In this manner, in this embodiment, the concentration of the cleaning liquid after the aggregates of contaminants are removed by the collection filter 228 is adjusted to satisfy the above-mentioned absorbance ratio. Then, the cleaning liquid with the adjusted concentration is applied to the conveyor belt when cleaning the conveyor belt. This makes it possible to increase the efficiency of removing the collected contaminants even when reusing the cleaning liquid.

[0058] [Other embodiments] It is to be noted that the above-described embodiment is merely an example, and it goes without saying that appropriate modifications are possible within the scope of the technical concept of the present invention.

[0059] For example, in the above embodiment, an image is formed using four color inks, YMCK, but an image may be formed using only one color, black ink.

[0060] In the above embodiment, the cleaning liquid is reused, but the cleaning liquid after use may be discharged without being reused. In this case, too, by making the cleaning liquid applied to the conveyor belt satisfy the above-mentioned absorbance ratio, the efficiency of removing contaminants from the cleaning liquid during waste liquid treatment can be increased.

[0061] 4, the liquid deposition unit 210 may clean the surface of the conveyor belt 110 at a plurality of locations by a plurality of nozzles 211, a plurality of cleaning brushes 214, and a plurality of scrapers 219. In this case, the liquid deposition unit 210 may have a plurality of receiving tanks 212 arranged at the respective cleaning positions, or may have one receiving tank 212 divided for each cleaning position (see FIG. 4). In this case, the concentration of the cleaning liquid collected from each cleaning position may be adjusted independently in the plurality of collection tanks 222 (see FIG. 4), or these cleaning liquids may be adjusted collectively in one collection tank 222. In the configuration shown in FIG. 4, the liquid collection unit 220 has a plurality of collection tanks 222. The concentration adjustment unit 230 adjusts the λ 回収液 and λ インク Ratio of (λ 回収液 / λ インク ), the adjustment liquid 310 from the adjustment liquid tank 232 or the color ink from the ink tank 124 is added to the respective collection tank 222.

[0062] In addition, in the above embodiment, the concentration of the cleaning liquid 300 was adjusted by adding color ink from the ink tank 124 to the collection tank 222, but the concentration of the cleaning liquid 300 may also be adjusted by adding a liquid with a high colorant concentration that is stored separately from the ink tank 124 to the collection tank 222.

[0063] In addition, in the above embodiment, the cleaning liquid 300 is applied to the conveying belt 110 by spraying from the nozzle 211, but the configuration may also be such that the rotating cleaning brush 214 comes into contact with the cleaning liquid 300 stored in the receiving tank 212, and the cleaning liquid 300 adhering to the cleaning brush 214 is applied to the conveying belt 110. EXAMPLES

[0064] The present invention will be specifically described below with reference to examples, but the scope of the present invention is not limited to the description of the examples.

[0065] 1. Ink Preparation 1-1. Preparation of Ink 1 To a preparation vessel, 20% by mass of ethylene glycol, 10 parts by mass of glycerin, 20 parts by mass of reactive dye (Reactive Black 5), 0.05 parts by mass of surfactant (Olfine E1010, manufactured by Nissin Chemical Industry Co., Ltd., "Olfine" is a registered trademark of the company), and 0.2 parts by mass of preservative (Proxel GXL, manufactured by SC Johnson) were added. Ion-exchanged water was further added so that the total amount became 100 parts by mass, and the mixture was thoroughly stirred. The aqueous solution obtained by the above stirring was filtered through a 1 μm (pore size) filter to obtain ink 1, which is a black ink.

[0066] 1-2. Preparation of Ink 2 to Ink 4 Inks 2 to 4, which are a yellow ink, a magenta ink and a cyan ink, were obtained in the same manner as in the preparation of ink 1, except that the reactive dye was changed to Reactive Yellow 95, Reactive Red 24 and Reactive Blue 72, respectively.

[0067] 1-3. Preparation of Ink 5 7 parts by mass of styrene-butyl acrylate-methacrylic acid copolymer (anionic dispersant, weight average molecular weight 16000, anionic group equivalent 3.5meq / g) was mixed with 78 parts by mass of ion-exchanged water, and then heated and stirred to prepare a neutralized pigment dispersant. 15 parts by mass of pigment (Pigment Black 7) was added to this mixture, premixed, and then dispersed using a sand grinder filled with 50% by volume of 0.5mm zirconia beads to obtain a black pigment dispersion with a pigment concentration of 15%.

[0068] 10 parts by mass of the above black pigment dispersion, 20 parts by mass of ethylene glycol, 10 parts by mass of glycerin, 0.05 parts by mass of a surfactant (Olfine E1010, manufactured by Nissin Chemical Industry Co., Ltd.), and 0.2 parts by mass of a preservative (Proxel GXL, manufactured by SC Johnson) were added, and ion exchanged water was further added to bring the total to 100 parts by mass, and the mixture was mixed and thoroughly stirred to obtain Ink 5, a black ink.

[0069] 2. Preparation of Washing Solutions As flocculants, polyaluminum chloride (PAC250A, manufactured by Taki Chemical Co., Ltd.), aluminum sulfate (Taki Chemical Co., Ltd.), ferric chloride (Toagosei Co., Ltd.), ferrous sulfate (Taki Chemical Co., Ltd.), and cationic polymer (PD-30, manufactured by Yokkaichi Synthetic Co., Ltd.) were used. As organic polymers, polyacrylamide (N-100T, manufactured by Taki Chemical Co., Ltd.) and sodium polyacrylate (A-108T, manufactured by Taki Chemical Co., Ltd.) were used. These were mixed with sodium hydroxide and ion-exchanged water in the ratios shown in Tables 1 to 3 to obtain cleaning solutions 1 to 12. Tables 1 to 3 also show the pH of cleaning solutions 1 to 12 measured with a pH meter (HM-41X, manufactured by DKK Toa Co., Ltd.). The unit of the ratio of each component shown in Tables 1 to 3 is mass%.

[0070] [Table 1]

[0071] [Table 2]

[0072] [Table 3]

[0073] 2. Evaluation Each ink was mixed with any one of cleaning solutions 1 to 12 so that the colorant concentration was 0.5% by mass, to obtain samples 1 to 16. Samples 1 to 16 were evaluated for absorbance, degree of self-aggregation, and degree of degradation of the base material by the following methods.

[0074] 2-1.Absorbance Ion-exchanged water was added to each ink so that the colorant concentration was 0.5% by mass to prepare a standard solution. The absorbance of each standard solution was measured using a spectrophotometer (V-500, manufactured by JASCO Corporation). The absorbance of the filtrate obtained by filtering Samples 1 to 16 through filter paper (manufactured by Advantec Co., Ltd.) was measured using the same spectrophotometer as that used to measure the standard solutions.

[0075] The absorbance (λ) at the maximum absorbance wavelength in the wavelength range of 350 nm to 800 nm measured for the standard solution obtained from the ink used to prepare the filtered sample to obtain each filtrate. インク ) and the absorbance at the same wavelength (λ 洗浄液 The absorbance was evaluated according to the following criteria by comparing the absorbance with that of the corresponding sample. A: λ 洗浄液 is λ インク The absorbance is 0.1% or more and 50% or less of the absorbance of B: λ 洗浄液 is λ インク Less than 0.1% or greater than 50% of the absorbance of

[0076] 2-2.Self-aggregation Samples 1 to 16 were filtered through filter paper (manufactured by Advantec Co., Ltd.), and the presence of self-aggregates of the flocculant on the filter paper was visually observed, and the degree of self-aggregation was evaluated according to the following criteria. A: No items of the same industry are found on the filter paper. B A small amount of autoagglutination can be seen on the filter paper. C. A certain amount of autoaggregates can be seen on the filter paper. D. A significant amount of autoaggregates can be seen on the filter paper.

[0077] 2-3. Deterioration of the ground material Samples 1 to 16 were used as cleaning solutions for the conveyor belt to which the ground-beam-forming agent was applied, and the conveyor belt was cleaned for three months while printing solid images with each of the inks 1 to 5 on a cotton broadcloth recording medium 130 for one hour per day using an image forming apparatus (Nassenger 8, manufactured by Konica Minolta, Inc.) filled with the corresponding inks 1 to 5. After three months, the adhesion of the conveyor belt and the stable conveyance of the fabric were confirmed, and the deterioration of the ground-beam-forming agent was evaluated according to the following criteria. A: The adhesiveness after 3 months is about the same as the initial adhesiveness, and fabric can be transported stably. B: After 3 months, the adhesiveness was slightly lower than the initial adhesiveness, but the fabric could still be transported stably. C: The adhesiveness after 3 months is significantly lower than the initial adhesiveness, and the fabric cannot be transported stably.

[0078] Table 4 shows the types of ink and cleaning solution used in the preparation of Samples 1 to 16, as well as the evaluation results of absorbance, self-aggregation, and degradation of the coating agent. 洗浄液 / λ インク ) are also shown.

[0079] [Table 4]

[0080] As is clear from Table 4, the ratio of absorbance (λ 洗浄液 / λ インク By using a cleaning solution with a colorant content of 0.01% or more and 50% or less, it was possible to suppress self-aggregation of the coagulant while also suppressing deterioration of the conveyor belt (background material) caused by colorant that was not completely removed by coagulation. [Industrial Applicability]

[0081] According to the present invention, the conveyor belt can be cleaned more efficiently with a cleaning liquid, and the cleaning liquid can also be reused more efficiently. If the cleaning liquid can be easily reused, the cost of waste liquid treatment and environmental pollution caused by the waste liquid can be reduced, and image formation using ink can be easily performed even in facilities that do not have waste liquid treatment equipment. Therefore, the present invention is expected to greatly contribute to the spread of image formation using ink. [Explanation of symbols]

[0082] 100 Image forming device 110 Conveyor belt 112a, 112b Pulleys 114 Feed roller 120 Image forming section 122 Inkjet head 124 Ink Tank 126 Ink tube 128 Valve 130 Recording media 200 Cleaning Equipment 210 Liquid application unit 211 Nozzle 212 Receiving tank 214 Cleaning Brush 214a Shaft 214b Brush section 219 Scraper 220 Liquid recovery section 222 Collection tank 224 Recovery Channel 226 Recovery Pump 228 Collection Filter 230 Density adjustment section 232 Adjustment liquid tank 234a, 234b Adjustment channel 236a, 236b Regulating pump 238a, 238b Regulating valve 240 Liquid supply section 244 Supply Channel 246 Supply Pump 248 Supply Filter 300 Cleaning Solution 310 Adjustment Fluid

Claims

1. 1. A method for cleaning a conveyor belt for forming an image by applying one or more types of color inks including a black ink to a recording medium conveyed on the conveyor belt, comprising the steps of: applying a cleaning liquid containing an inorganic flocculant to the conveyor belt after the recording medium has been moved to another member; and recovering the applied cleaning liquid. The cleaning solution applied has an absorbance (λ ) of the black ink, the concentration of which has been adjusted to 0.5 mass % by adding ion-exchanged water, at a maximum absorbance wavelength in the wavelength range of 350 nm to 800 nm. インク ) at the maximum absorption wavelength of the filtrate obtained by filtering the recovered cleaning solution. 洗浄液 ) ratio (λ 洗浄液 / λ インク ) is 0.01% or more and 50% or less; Cleaning method:

2. The ratio (λ 洗浄液 / λ インク ) is 0.1% or more and 30% or less; The cleaning method according to claim 1 .

3. The cleaning solution comprises an inorganic flocculant selected from the group consisting of polyaluminum chloride, aluminum sulfate, ferric chloride, and ferrous sulfate; The cleaning method according to claim 1 .

4. The amount of the inorganic flocculant is 0.01% by mass or more and 5% by mass or less based on the total mass of the cleaning liquid. The cleaning method according to claim 1 .

5. The color ink is an ink containing a colorant selected from the group consisting of reactive dyes, disperse dyes, acid dyes, and pigments. The cleaning method according to claim 1 .

6. The cleaning solution includes an organic polymer. The cleaning method according to claim 1 .

7. The organic polymer is polyacrylamide or sodium polyacrylate; The cleaning method according to claim 6.

8. The cleaning solution has a pH of 4 or more and 6 or less. The cleaning method according to claim 1 .

9. filtering the collected cleaning solution and adjusting the concentration of the filtered cleaning solution; applying the cleaning liquid having the adjusted concentration to the conveyor belt; having The cleaning method according to claim 1 .

10. The recording medium is a fabric. The cleaning method according to claim 1 .

11. conveying a recording medium on a conveyor belt; applying one or more color inks, including a black ink, to the recording medium to form an image; and cleaning the conveyor belt after the recording medium has been moved to another member using the cleaning method according to any one of claims 1 to 10. Image forming method.

12. A conveyor belt for conveying a recording medium; an image forming unit that applies one or more types of color inks, including a black ink, to the recording medium transported on the transport belt to form an image, the image forming unit being attached to the image forming apparatus, A liquid applying unit that applies a cleaning liquid to the conveyor belt; a liquid recovery unit that recovers the applied cleaning liquid; The concentration of the collected cleaning solution was adjusted by adding ion-exchanged water to a colorant concentration of 0.5% by mass, and the absorbance (λ) of the black ink at the maximum absorption wavelength in the wavelength range of 350 nm to 800 nm was measured. インク ) at the maximum absorption wavelength of the filtrate obtained by filtering the recovered cleaning solution. 洗浄液 ) ratio (λ 洗浄液 / λ インク and a concentration adjusting unit that adjusts the concentration of the ink to be 0.01% or more and 50% or less. Cleaning equipment.

13. A conveyor belt for conveying a recording medium; an image forming section that applies one or more types of color ink, including black ink, to a recording medium transported on the transport belt to form an image; and a cleaning device according to claim 12, which cleans the conveyor belt after the recording medium has been moved to another member. Image forming device.

14. a concentration measuring device for measuring the concentration of the cleaning liquid collected by the liquid collecting unit; The image forming apparatus according to claim 13.

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