Image forming system and image forming method

Abstract

To provide an image forming system and an image forming method that achieve both the color fastness to rubbing of images and the ejection suitability of ink.SOLUTION: Provided is an image forming system using ink, the image forming system including: an inkjet head that ejects the ink onto a recording medium; and a wiping mechanism that rubs and cleans a nozzle face of the inkjet head. The ink contains a silicone resin. A content A of an oily silicone compound in the ink is less than 1000 ppm by mass.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an image forming system and an image forming method.

Background Art

[0002] Image formation using ink is a printing method in which ink components are deposited on the surface of a recording medium, so friction fastness can be a problem. On the other hand, by including a silicone resin in the ink, the slipperiness of the image surface can be improved, and the friction fastness can be improved (see Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when a silicone resin is included in the ink, an oily silicone compound may be brought into the ink together with the silicone resin. When ink containing a large amount of the oily silicone compound is ejected from a nozzle by an inkjet method, it has been confirmed that an oily deposit is formed on the nozzle surface, and ejection failure is likely to occur.

[0005] The present invention has been made in view of the above circumstances. The problem to be solved by the present invention is to provide an image forming system and an image forming method that achieve both the friction fastness of an image and the ejection suitability of ink.

Means for Solving the Problems

[0006] The above problems according to the present invention are solved by the following means.

[0007] 1. An image forming system using ink, comprising: an inkjet head that discharges the ink onto a recording medium; a wiping mechanism that wipes and cleans the nozzle surface of the inkjet head; wherein the ink contains a silicone resin; wherein the content A of the oily silicone compound in the ink is less than 1000 mass ppm; an image forming system.

[0008] 2. The oily silicone compound is cyclotetrasiloxane; the image forming system according to claim 1.

[0009] 3. The content A of the oily silicone compound in the ink is 1 mass ppm or more and less than 250 mass ppm; the image forming system according to claim 2.

[0010] 4. The content B of the silicone resin in the ink is 0.1 mass% or more; the image forming system according to claim 1.

[0011] 5. The ratio (A / B) of the content A of the oily silicone compound to the content B of the silicone resin in the ink is less than 0.06; the image forming system according to claim 2.

[0012] 6. The ink contains a pigment; the image forming system according to claim 1.

[0013] 7. The wiping mechanism is of a roller type and has a water-absorbent sponge roller; the image forming system according to claim 1.

[0014] 8. The recording medium is a fabric; the image forming system according to claim 1.

[0015] 9. An image forming method using ink, comprising: a step of ejecting the ink onto a recording medium by an inkjet head; a step of cleaning by wiping a nozzle surface of the inkjet head with a wiping mechanism; wherein the ink contains a silicone resin; wherein a content A of an oily silicone compound in the ink is less than 1000 mass ppm; an image forming method.

Advantages of the Invention

[0016] According to the present invention, it is possible to achieve both the rubbing fastness of an image and the ejection suitability of ink.

[0017] Although the mechanism of expression or the mechanism of action of the effects of the present invention is not clear, it is presumed as follows.

[0018] In the present invention, since the ink contains a silicone resin, the rubbing fastness of the image is improved. Further, in the present invention, the content A of the oily silicone compound in the ink is less than 1000 mass ppm, and the ejection suitability of the ink is improved by the wiping mechanism wiping the nozzle surface of the inkjet head for cleaning.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described. The effects and features of one or more embodiments of the present invention will be understood from the following detailed description and drawings. Note that the following detailed description and drawings are provided for illustrative purposes only and do not limit the scope of the present invention.

[0021] Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the present invention is not limited to the disclosed embodiments.

[0022] In the present application, "~" is used to mean including the numerical values described before and after it as the lower limit value and the upper limit value.

[0023] FIG. 1 is a schematic diagram of an image forming system 1 according to an embodiment of the present invention. The image forming system 1 shown in FIG. 1 is an inkjet type and includes a belt conveyance device 2, an inkjet head 3, and a wiping mechanism 4.

[0024] An endless conveyance belt 23 having a predetermined width is stretched across a driving roller 21 and a driven roller 22 that are arranged in parallel at a predetermined interval in the belt conveyance device 2.

[0025] The upper surface of the conveyance belt 23 stretched across the driving roller 21 and the driven roller 22 is a placement surface on which the recording medium P is placed in close contact. An adhesive for bringing the recording medium P being conveyed into close contact with the upper surface of the conveyance belt 23 may be applied to the surface of the conveyance belt 23.

[0026] The driving roller 21 is driven by a motor (not shown) and rotates at a predetermined speed in the counterclockwise direction (arrow direction) in FIG. 1. By this operation, the recording medium P placed on the upper surface of the conveyance belt 23 is conveyed in the direction of arrow A in the figure.

[0027] For the recording medium P, for example, recording media commonly used in inkjet recording such as fabrics, paper, plastic films, glass plates, etc. can be used. The recording medium P may be in the form of a sheet cut to a predetermined size, or may be a long strip continuously fed from a master roll wound in a roll shape.

[0028] When the recording medium P is a fabric, in the prior art, the rubbing fastness of the image tends to be a problem, but by applying the present invention, even if the recording medium P is a fabric, the rubbing fastness of the image is less likely to be a problem.

[0029] The fabric can be, for example, a fabric containing natural fibers (including natural cellulose fibers, hemp, wool, silk, etc.), synthetic cellulose fibers (including regenerated cellulose fibers such as rayon and semi-synthetic cellulose fibers such as acetate), vinylon fibers, nylon fibers, acrylic fibers, polyurethane fibers, polyester fibers, etc. The fabric may be in any form such as a woven fabric, a non-woven fabric, or a knitted fabric made of these fibers. Also, the fabric may be a blended woven fabric or a blended non-woven fabric of two or more types of fibers.

[0030] On the side opposite to the placement surface of the recording medium P in the belt conveyance device 2, a belt cleaning device (not shown) may be provided. The belt cleaning device removes foreign matter adhering to the conveyance belt 23.

[0031] The inkjet head 3 is disposed at a predetermined interval above the placement surface of the recording medium P on the conveyance belt 23. The inkjet head 3 has a nozzle surface 3A having a large number of nozzles on its lower surface. The inkjet head 3 records a desired image on the recording medium P by discharging ink from the nozzle surface 3A toward the recording medium P conveyed by the conveyance belt 23.

[0032] In the embodiment shown in FIG. 1, the inkjet head 3 is of a line type fixedly spanned across the width direction of the conveyance belt 23. In this case, the drive of the drive roller 21 is controlled so that the conveyance belt 23 moves continuously (rotates) during recording.

[0033] Note that the inkjet head 3 may be of a shuttle type mounted on a carriage (not shown) and reciprocating in a main scanning direction orthogonal to the conveyance direction of the recording medium P. In this case, the drive of the drive roller 21 is controlled so that the conveyance belt 23 performs an intermittent operation of repeating a standby state and a drive state during recording.

[0034] The wiping mechanism 4 wipes and cleans the nozzle surface 3A of the inkjet head 3. "Wiping and cleaning the nozzle surface 3A" means cleaning the nozzle surface 3A while bringing the wiping mechanism 4 into contact with the nozzle surface and applying a force at least in the surface direction. A cleaning mechanism that only presses the wiping mechanism 4 against the nozzle surface 3A in the vertical direction to clean the nozzle surface is not included in the wiping mechanism 4 according to the present invention.

[0035] When the image forming system 1 does not have a cleaning mechanism for the nozzle surface 3A, or when it only has a cleaning mechanism that cleans without wiping the nozzle surface 3A, the nozzle surface 3A is not sufficiently cleaned, and ejection failure is likely to occur. Particularly when the ink contains a silicone resin, this problem becomes prominent because an oily silicone compound brought into the ink together with the silicone resin easily adheres to the nozzle surface 3A. On the other hand, in the image forming system 1 of the present invention, the nozzle surface 3A of the inkjet head 3 is appropriately cleaned by the wiping mechanism 4, so that the ink ejection suitability is improved.

[0036] The wiping mechanism 4 can be a roller type, a blade type, a web type, or the like. From the viewpoint of cleaning force, the wiping mechanism 4 is preferably of a roller type using a water-absorbent sponge roller.

[0037] FIG. 2 is a schematic diagram illustrating a roller-type wiping mechanism 4.

[0038] The roller wiping mechanism 4 shown in FIG. 2 includes a wiping member 411, a storage member 412, and a squeezing member 413. The wiping mechanism 4 is capable of relative movement in the Y direction with respect to the nozzle surface 3A of the inkjet head 3. The Y direction may be determined as appropriate. The Y direction may be, for example, the conveyance direction of the conveyance belt 23 or the width direction of the conveyance belt 23.

[0039] The wiping mechanism 4 is configured to be reciprocally movable between one end and the other end of the nozzle surface 3A in the Y direction. The roller wiping mechanism 4 relatively moves in the Y direction while bringing the wiping member 411 into contact with the nozzle surface 3A to wipe the nozzle surface 3A. Thereby, the roller wiping mechanism 4 cleans the deposits on the nozzle surface 3A.

[0040] At this time, when the wiping mechanism 4 moves in the Y direction, the nozzle surface 3A may be wiped by the wiping mechanism 4, or when the inkjet head 3 moves in the Y direction, the nozzle surface 3A may be wiped by the wiping mechanism 4. Further, when the inkjet head 3 is configured not to be movable, in order to secure a movable area for the wiping mechanism 4, for example, the belt conveyance device 2 is configured to retract from the area. Further, when the inkjet head 3 is configured to be movable, for example, the wiping mechanism 4 is arranged at a position different from the belt conveyance device 2 in the Y direction, and the inkjet head 3 is configured to move to a position corresponding to the wiping mechanism 4.

[0041] The wiping member 411 is a roller member that wipes deposits on the nozzle surface 3A of the inkjet head 3. The surface layer of the wiping member 411 is an elastic member capable of absorbing deposits such as ink. As the elastic member, for example, a porous material such as a sponge is used. The material of the elastic member is preferably a material having continuous bubbles such as a plastic polymer, and a polyurethane material that easily absorbs cleaning liquid and ink is more preferable. The wiping member 411 is preferably a water-absorbing sponge roller from the viewpoint of cleaning power. The water-absorbing sponge roller is a roller whose surface layer is composed of an absorbent sponge.

[0042] The wiping member 411 is rotatably supported, for example, by a housing (not shown) constituting the wiper mechanism 4. As the wiping member 411 relatively moves in the Y direction of the wiper mechanism 4, it rotates so as to wipe the nozzle surface 3A of the inkjet head 3. As long as the wiping member 411 rotates so as to wipe the nozzle surface 3A of the inkjet head 3, the rotation direction of the wiping member 411 is not limited.

[0043] The storage member 412 is, for example, a tub configured to be able to store a cleaning liquid W in which the wiping member 411 can be immersed. The cleaning liquid W may be any liquid as long as it can clean the nozzle surface 3A, and is, for example, pure water.

[0044] The storage member 412 is disposed at a position where the wiping member 411 can enter therein, and is rotatably supported by a predetermined rotation axis 412A. The rotation axis 412A is provided at an appropriate position of the housing of the wiper mechanism 4.

[0045] A predetermined amount of the cleaning liquid W is stored in the storage member 412. The storage member 412 can rotate so as to immerse the wiping member 411 in the cleaning liquid W or separate the wiping member 411 from the cleaning liquid W.

[0046] The squeezing member 413 is, for example, a shaft member extending in the X direction, and is disposed to face the wiping member 411 in the Y direction. The squeezing member 413 is configured to be able to press the surface layer of the wiping member 411. The squeezing member 413 can be adjusted so as to reduce the water content in the wiping member 411 that has absorbed the cleaning liquid W by pressing and squeezing the surface layer of the wiping member 411 to be less than before adjustment.

[0047] The squeezing member 413 may have any configuration as long as it can squeeze the cleaning liquid from the surface layer of the wiping member 411. The squeezing member 413 may be configured to be able to adjust the pressing amount on the wiping member 411.

[0048] FIG. 3 is a schematic diagram illustrating the blade type wiping mechanism 4. The blade type wiping mechanism 4 shown in FIG. 3 has a blade member 42. The blade member 42 is made of, for example, plate-shaped rubber. The blade type wiping mechanism 4 relatively moves in the Y direction while bringing the blade member 42 into contact with the nozzle surface 3A, and wipes the nozzle surface 3A. Thereby, the blade type wiping mechanism 4 cleans the deposits on the nozzle surface 3A.

[0049] FIGS. 4 and 5 are schematic diagrams illustrating the web type wiping mechanism 4. The web type wiping mechanism 4 shown in FIGS. 4 and 5 has a feeding roller 431, a winding roller 432, and a web 433. The web 433 is fed out from the feeding roller 431 and wound around the winding roller 432. The web 433 is a long sheet made of, for example, non-woven fabric.

[0050] In the case of the web type wiping mechanism 4 shown in FIG. 4, the web 433 is pressed in the direction of the nozzle surface 3A by a sponge member 434 and a plurality of springs 436. By relatively moving the web 433 in the Y direction in this state, the web type wiping mechanism 4 shown in FIG. 4 wipes the nozzle surface 3A. Thereby, the web type wiping mechanism 4 shown in FIG. 4 cleans the deposits on the nozzle surface 3A.

[0051] In the case of the web type wiping mechanism 4 shown in FIG. 5, the web 433 is pressed in the direction of the nozzle surface 3A by a sponge roller 435 and a spring 436. In the web type wiping mechanism 4 shown in FIG. 5, not only is the web 433 fed out while wiping the nozzle surface 3A, but also the feeding roller 431, the winding roller 432, and the web 433 relatively move integrally in the Y direction. Thereby, the web type wiping mechanism 4 shown in FIG. 5 cleans the deposits on the nozzle surface 3A.

[0052] Next, the ink according to the present invention will be described.

[0053] The ink according to the present invention contains a silicone resin. Further, in the ink according to the present invention, the content A of the oily silicone compound is less than 1000 mass ppm.

[0054] In the present invention, the "silicone resin" refers to a compound having a polysiloxane structure and being solid under standard conditions (temperature 25 °C, pressure 100 kPa). Solids include glassy and rubbery states.

[0055] When the ink contains a silicone resin, the slipperiness of the surface of the image is improved, and the rubbing fastness is improved.

[0056] The content B of the silicone resin with respect to the total amount of the ink is preferably 0.1 mass% or more. Thereby, the rubbing fastness of the image is further improved. The content B is preferably 10 mass% or less, and more preferably 5 mass% or less. The silicone resin contained in the ink may be only one kind or two or more kinds.

[0057] Examples of the silicone resin include silicone-modified urethane resin, silicone-modified epoxy resin, silicone-modified acrylic resin, silicone-modified polyimide, silicone-modified polyamide, silicone-modified polycarbonate, silicone-modified polyester, and the like. The silicone-modified acrylic resin is, for example, a silicone acrylic graft copolymer.

[0058] In the present invention, the "oily silicone compound" refers to a compound that is liquid under standard conditions (temperature 25 °C, pressure 100 kPa) among organosilicon compound polymers having a polysiloxane structure as a basic skeleton.

[0059] When the content A of the oily silicone compound with respect to the total amount of the ink is less than 1000 mass ppm, oily deposits are less likely to occur on the nozzle surface, and the ejection suitability of the ink is improved.

[0060] The content rate A of the oily silicone compound is preferably less than 500 ppm by mass, more preferably less than 250 ppm by mass. Thereby, an oily deposit is less likely to occur on the nozzle surface, and the ink ejection suitability is further improved.

[0061] On the other hand, the content rate A is preferably 1 ppm by mass or more. The oily silicone compound has an effect of improving the slipperiness of the surface of the image and improving the friction fastness of the image. Therefore, when the content rate A is 1 ppm by mass or more, the friction fastness of the image is further improved. The oily silicone compound contained in the ink may be only one kind or two or more kinds.

[0062] Examples of the oily silicone compound include straight silicone dimethicone, trisiloxane, cyclic silicone cyclotetrasiloxane, cyclopentasiloxane, cyclohexasiloxane, cyclomethicone, diphenyldimethylsilicone with a substituent introduced, phenyltrimethicone, diphenylsiloxyphenyltrimethicone, hydrogen dimethicone, methicone, methyltrimethicone, modified silicone oils such as amino-modified silicone.

[0063] The oily silicone compound in the ink according to the present invention is preferably cyclotetrasiloxane. Cyclotetrasiloxane is particularly likely to cause deposits on the nozzle surface. Therefore, when the content rate of cyclotetrasiloxane is less than 1000 ppm by mass, the ink ejection suitability is further improved. Further, when the content rate of cyclotetrasiloxane is less than 500 ppm by mass, the ink ejection suitability is further improved. When the content rate of cyclotetrasiloxane is less than 250 ppm by mass, the ink ejection suitability is further improved. Since cyclotetrasiloxane has an effect of improving the slipperiness of the surface of the image, when the content rate of cyclotetrasiloxane is 1 ppm by mass or more, the friction fastness of the image is further improved.

[0064] The ratio (A / B) of the content A of the oily silicone compound to the content B of the silicone resin is preferably less than 0.06. Thereby, the rubbing fastness of the image and the ejection suitability of the ink are compatible at a high level. The ratio (A / B) is more preferably less than 0.05, and even more preferably less than 0.04.

[0065] The ink may or may not contain a coloring material. The ink containing a coloring material can be used, for example, as a colored ink. The ink not containing a coloring material can be used, for example, as a pretreatment liquid, an overcoat liquid, or the like.

[0066] The coloring material may be a pigment or a dye. When the ink contains a pigment, the rubbing fastness of the image tends to be a problem in the prior art. However, by applying the present invention, even if the ink contains a pigment, the rubbing fastness of the image is less likely to be a problem.

[0067] As the pigment, an organic pigment or an inorganic pigment such as titanium oxide can be preferably used.

[0068] Examples of the organic pigment include azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindoline, azine, oxazine, thiazine, dioxazine, thiazole, phthalocyanine, diketopyrrolopyrrole, and the like.

[0069] Examples of organic pigments for magenta or red include, for example, C.I. Pigment Red 2, C.I. Pigment Red 3, C.I. Pigment Red 5, C.I. Pigment Red 6, C.I. Pigment Red 7, C.I. Pigment Red 15, C.I. Pigment Red 16, C.I. Pigment Red 48:1, C.I. Pigment Red 53:1, C.I. Pigment Red 57:1, C.I. Pigment Red 122, C.I. Pigment Red 123, C.I. Pigment Red 139, C.I. Pigment Red 144, C.I. Pigment Red 149, C.I. Pigment Red 166, C.I. Pigment Red 177, C.I. Pigment Red 178, C.I. Pigment Red 202, C.I. Pigment Red 222, C.I. Pigment Violet 19, and the like.

[0070] Examples of organic pigments for orange or yellow include, for example, C.I. Pigment Orange 31, C.I. Pigment Orange 43, C.I. Pigment Yellow 12, C.I. Pigment Yellow 13, C.I. Pigment Yellow 14, C.I. Pigment Yellow 15, C.I. Pigment Yellow 15:3, C.I. Pigment Yellow 17, C.I. Pigment Yellow 74, C.I. Pigment Yellow 93, C.I. Pigment Yellow 128, C.I. Pigment Yellow 94, C.I. Pigment Yellow 138, C.I. Pigment Yellow 155, and the like.

[0071] Examples of organic pigments for green or cyan include, for example, C.I. Pigment Blue 15, C.I. Pigment Blue 15:2, C.I. Pigment Blue 15:3, C.I. Pigment Blue 16, C.I. Pigment Blue 60, C.I. Pigment Green 7, and the like.

[0072] Examples of organic pigments for black include, for example, C.I. Pigment Black 1, C.I. Pigment Black 6, C.I. Pigment Black 7, and the like.

[0073] Titanium oxide has three crystal forms: anatase type, rutile type, and brookite type. Generally, it can be broadly classified into anatase type and rutile type. Although not particularly limited, rutile type with a high refractive index and high hiding power is preferred. Specifically, examples of titanium oxide include the TR series of Fuji Titanium Industry Co., Ltd., the JR series of Tayca Corporation, and Typak of Ishihara Sangyo Co., Ltd.

[0074] The pigment may be a self-dispersing pigment. A self-dispersing pigment is one in which the surface of pigment particles is modified with a group having a hydrophilic group, and has pigment particles and a hydrophilic group bonded to the surface thereof.

[0075] Examples of hydrophilic groups include carboxy group, sulfonic acid group, phosphorus-containing group, etc. Examples of phosphorus-containing groups include phosphoric acid group, phosphonic acid group, phosphinic acid group, phosphite group, phosphate group, etc.

[0076] Examples of commercially available self-dispersing pigments include Cabot Cab-0-Jet® 200K, 250C, 260M, 270V (sulfonic acid group-containing self-dispersing pigment), Cab-0-Jet® 300K (carboxylic acid group-containing self-dispersing pigment), Cab-0-Jet® 400K, 450C, 465M, 470V, 480V (phosphoric acid group-containing self-dispersing pigment), etc.

[0077] The content of the coloring material in the ink is preferably in the range of 1 to 10% by mass, more preferably in the range of 1 to 5% by mass, based on the total amount of the ink. The coloring material contained in the ink may be only one kind or two or more kinds.

[0078] The ink may contain a resin other than silicone resin. Thereby, the rubbing fastness of the image is further improved. The resin other than silicone resin may be cationic or anionic.

[0079] Examples of cationic resins include, for example, polyallylamine, allylamine diallylamine copolymer, polydiallylamine, polymethyldiallylamine, diallylamine sulfur dioxide copolymer, methyldiallylamine sulfur dioxide copolymer, polyvinylamine, polyethyleneimine, polydiallyldimethylammonium chloride, and the like.

[0080] Examples of products containing cationic resins include, for example, the following. · RKW series and WEM series manufactured by Taisei Fine Chemical Co., Ltd. · Vinibran 1008, 1028, 2687 manufactured by Nissin Chemical Industry Co., Ltd. · Sumiflock FC-A, FC-B, FC-L, FC-373, FC-200, FC-C, FC-E manufactured by Sumitomo Chemical Co., Ltd. · Sunflock C-450, C-454 manufactured by Sanyo Chemical Industries, Ltd. · Himoro Rock MP series, E series, M-966 manufactured by Himoro Co., Ltd. · Epomin series manufactured by Nippon Shokubai Co., Ltd. · Cation Master series manufactured by Yokkaichi Gosei Co., Ltd. · MPT series manufactured by Mitsubishi Pencil Co., Ltd. · PAS series manufactured by Nitto Boehringer Medical Co., Ltd.

[0081] Examples of anionic resins include polyesters, polyurethanes, polyacrylics, polymethacrylics, etc. having acidic groups such as carboxy groups, sulfonyl groups, phosphorus-containing groups (phosphoric acid groups or phosphonic acid groups).

[0082] Examples of products containing anionic resins include, for example, the following. · Acryset EMN series manufactured by Nippon Shokubai Co., Ltd. · NeoCryl series manufactured by Kusumoto Chemical Co., Ltd. · Joncryl series manufactured by BASF · Takelac series manufactured by Mitsui Chemicals, Inc. · HUX series manufactured by ADEKA · Evafanol series manufactured by Nichika Chemical Co., Ltd. ·Superflex series manufactured by Daiichi Pharmaceutical Co., Ltd.

[0083] The content rate of resins other than silicone resin in the ink is preferably in the range of 1 to 20% by mass, more preferably in the range of 5 to 10% by mass, based on the total amount of the ink. The resins other than silicone resin contained in the ink may be only one kind or two or more kinds.

[0084] The ink may contain a solvent. Examples of the solvent include organic solvents, water, etc. The content rate of the solvent in the ink is preferably in the range of 90 to 99% by mass, based on the total amount of the ink. The solvent contained in the ink may be only one kind or two or more kinds.

[0085] Examples of water include ion-exchanged water, distilled water, pure water, etc.

[0086] The organic solvent is preferably a water-soluble organic solvent.

[0087] Examples of water-soluble organic solvents include monohydric alcohols (e.g., methanol, ethanol, propanol, pentanol, hexanol, cyclohexanol, benzyl alcohol), polyhydric alcohols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, glycerin, butylene glycol, hexanediol, pentanediol, hexanetriol, thiodiglycol, the compound represented by the following general formula (1), 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2-heptanediol, trimethylolpropane), polyhydric alcohol ethers (e.g., ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, tripropylene glycol monoethyl ether), amines (e.g., ethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine), amides (e.g., formamide, N,N-dimethylformamide, N,N-dimethylacetamide), heterocyclics (e.g., 2-pyrrolidone, N-methyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidine), sulfoxides (e.g., dimethyl sulfoxide), sulfones (e.g., sulfolane), etc.

[0088]

Chem.

[0089] [In general formula (1), R 11 represents an ethylene glycol group or a propylene glycol group. x, y, and z are all positive integers. The sum of x, y, and z is 3 to 30.]

[0090] The ink may contain a surfactant. Examples of the surfactant include anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, and the like.

[0091] The ink may contain a preservative. Examples of the preservative include aromatic halogen compounds (for example, Preventol CMK), methylene dithiocyanate, halogen-containing nitrogen-sulfur compounds, 1,2-benzisothiazolin-3-one (for example, PROXEL GXL), and the like.

[0092] The ink may contain a pH adjuster. Examples of the pH adjuster include citric acid, sodium citrate, hydrochloric acid, sodium hydroxide, and the like.

[0093] The ink may further contain other components other than those described above, as necessary, as long as the effects of the present invention are not impaired.

[0094] The ink can be prepared by mixing the above components. The mixing method is not particularly limited and may be a conventionally known method. The silicone resin is preferably mixed with other components in the form of an aqueous dispersion. When preparing an ink containing a pigment, it is preferable to prepare a pigment dispersant containing a pigment, a pigment dispersant, water, etc., and then mix the pigment dispersion liquid with other components. Thereby, both the rubbing fastness of the image and the ejection suitability of the ink can be achieved.

[0095] As described above, the image forming system of the present invention is an image forming system that uses ink, and includes an inkjet head and a wiping mechanism. The inkjet head discharges ink onto a recording medium. The wiping mechanism wipes and cleans the nozzle surface of the inkjet head. The ink contains a silicone resin. The content A of the oily silicone compound in the ink is less than 1000 mass ppm. Thereby, both the friction fastness of the image and the ejection suitability of the ink can be achieved.

[0096] The oily silicone compound is preferably cyclotetrasiloxane. Cyclotetrasiloxane is particularly likely to cause deposits on the nozzle surface. Therefore, when the content of cyclotetrasiloxane is less than 1000 mass ppm, the ejection suitability of the ink is further improved.

[0097] The content of cyclotetrasiloxane in the ink is preferably 1 mass ppm or more and less than 250 mass ppm. When the content is less than 250 mass ppm, oily deposits on the nozzle surface are less likely to occur, and the ejection suitability of the ink is further improved. When the content is 1 mass ppm or more, the friction fastness of the image is further improved.

[0098] The content B of the silicone resin in the ink is preferably 0.1 mass% or more. Thereby, the friction fastness of the image is further improved.

[0099] The ratio (A / B) of the content A of the oily silicone compound to the content B of the silicone resin in the ink is preferably less than 0.06. Thereby, both the friction fastness of the image and the ejection suitability of the ink are achieved at a high level.

[0100] The ink may contain a pigment. When the ink contains a pigment, the friction fastness of the image tends to be a problem in the prior art. However, by applying the present invention, even when the ink contains a pigment, the friction fastness of the image is less likely to be a problem.

[0101] The wiping mechanism is preferably of a roller type and has a water-absorbent sponge roller. This improves the cleaning power of the nozzle surface.

[0102] The recording medium may be a fabric. When the recording medium is a fabric, the rubbing fastness of the image tends to be a problem in the prior art. However, by applying the present invention, even when the recording medium is a fabric, the rubbing fastness of the image is less likely to be a problem.

[0103] The image forming method of the present invention is an image forming method using ink. The image forming method includes a step of discharging ink from an inkjet head onto a recording medium, and a step of wiping and cleaning the nozzle surface of the inkjet head by a wiping mechanism. The ink contains a silicone resin. The content A of the oily silicone compound in the ink is less than 1000 mass ppm. This enables both the rubbing fastness of the image and the ejection suitability of the ink.

[0104] Although the embodiments of the present invention have been described and illustrated in detail, the disclosed embodiments are for illustrative and exemplary purposes only and not for limitation. The scope of the present invention should be construed according to the description of the claims.

Examples

[0105] Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the following examples, unless otherwise specified, the operations were carried out in a standard environment of 25 °C and 50% RH. Also, unless otherwise specified, “%”, “ppm” and “parts” mean “mass %”, “mass ppm” and “mass parts” respectively.

[0106] [Preparation of pretreatment liquid] The following materials were mixed to obtain a pretreatment liquid for inkjet. Propylene glycol (humectant solvent) 20 mass % Glycerin (humectant solvent) 10 mass % Surfynol E1010 (surfactant) 0.1 mass % Proxcel GXL(S) (preservative) 0.05% by mass Quaternary salt of alkylamine-epichlorohydrin adduct 2% by mass Ion-exchanged water 67.85% by mass

[0107] Surfynol E1010 is an acetylene glycol-based surfactant manufactured by Nissin Chemical Industry Co., Ltd. Proxcel GXL(S) is manufactured by Lonza.

[0108] [Preparation of Pigment Dispersion Liquid] A pigment dispersant [7 parts by mass] and water [63 parts by mass] were mixed. As the pigment dispersant, a styrene-butyl acrylate-methacrylic acid copolymer (anionic dispersant, weight-average molecular weight: 16,000, anionic group equivalent: 3.5 meq / g) was used. The obtained mixture was heated and stirred. Sodium hydroxide corresponding to a neutralization degree of 50% was added to this mixture to prepare a neutralized product of the pigment dispersant. Carbon black [30 parts by mass] was added to this mixture and pre-mixed. Using a sand grinder filled with 0.5 mm zirconia beads at a volume ratio of 50%, the carbon black in the mixture was dispersed. As a result, a black pigment dispersion liquid with a pigment concentration (= solid content ratio) of 30% by mass was obtained.

[0109] [Silicone Material] As the silicone material, products manufactured by Nissin Chemical Industry Co., Ltd. described in Table I were used. All the silicone materials used contain a silicone acrylate graft copolymer which is a silicone resin and cyclotetrasiloxane which is an oily silicone compound. The solid content ratio in each silicone material is the same as the content ratio of the silicone resin.

[0110]

Table 1

[0111] [Preparation of Ink to be Evaluated] So as to obtain the compositions described in Table II and Table III, the above pigment dispersion, fixing resin dispersion (Takelac W-6061, manufactured by Mitsui Chemicals, solid content ratio 30% by mass), the above various silicone materials, cyclotetrasiloxane, various organic solvents, surfactant (Surfinol E1010, manufactured by Nissin Chemical Industry Co., Ltd., acetylene glycol type), preservative (Proxcel GXL(S), manufactured by Lonza) and ion-exchanged water were appropriately mixed to prepare Inks 1 to 14 respectively. The cyclotetrasiloxane in Inks 1 to 13 is derived from the above various silicone materials. The cyclotetrasiloxane in Ink 14 is added alone. The remaining water contains the water brought in by the pigment dispersion and the like and the ion-exchanged water added separately.

[0112]

Table 2

[0113]

Table 3

[0114] [Preparation of Coloring Liquid] So as to obtain the composition described in Table IV, the above pigment dispersion, various organic solvents, surfactant (Surfinol E1010, manufactured by Nissin Chemical Industry Co., Ltd., acetylene glycol type), preservative (Proxcel GXL(S), manufactured by Lonza) and ion-exchanged water were appropriately mixed to prepare a coloring liquid. The remaining water contains the water brought in by the pigment dispersion and the like and the ion-exchanged water added separately.

[0115]

Table 4

[0116] [Evaluation of Rubbing Fastness] An image was formed on the fabric by an inkjet method using a simple printing tester equipped with an inkjet head KM1024i (manufactured by Konica Minolta). The image was a 100% solid image of 200 mm × 200 mm. Cotton satin was used for the fabric.

[0117] Image formation using Inks 1 to 12 containing pigments was specifically carried out according to the following procedure. The above-prepared pretreatment liquid and the ink to be evaluated (any one of Inks 1 to 12) were introduced into the simple printing tester. The pretreatment liquid and the ink to be evaluated were continuously applied onto the fabric in this order to form an image. The application amount of the pretreatment liquid was 15 g / m 2 and that of the ink was 30 g / m 2 . After the image was formed, the fabric was peeled off from the belt and dried at 150°C for 3 minutes.

[0118] Image formation using Inks 13 and 14 not containing pigments was specifically carried out according to the following procedure. Here, Inks 13 and 14 were used as overcoat liquids. The above-prepared pretreatment liquid, coloring liquid, and the ink to be evaluated (any one of Inks 13 and 14) were introduced into the simple printing tester. The pretreatment liquid, coloring liquid, and the ink to be evaluated were continuously applied onto the fabric in this order to form an image. The application amount of the pretreatment liquid was 15 g / m 2 and those of the coloring liquid and the ink to be evaluated were each 30 g / m 2 . After the image was formed, the fabric was peeled off from the belt and dried at 150°C for 3 minutes.

[0119] For the fabric after the obtained image was formed, a dry rubbing fastness test was carried out using a type II tester according to the conditions of JIS L0849 (2013) to evaluate the rubbing fastness. Specifically, for a region of 100 mm in the horizontal direction × 100 mm in the vertical direction of the part where the image was formed, using a cotton cloth, friction was applied with a load of 200 g for 100 reciprocations. After the friction was applied, the color adhered to the cotton cloth was observed. Based on the observation results and the following criteria, the rubbing fastness was evaluated. The evaluation result of 3 or more is within the acceptable range. The evaluation results are as shown in Table V.

[0120] 5: There was no color bleeding. 4: There was almost no color bleeding. 3: There was color bleeding, but it was within the allowable range. 2: There was color bleeding and it was not within the allowable range. 1: There was significant color bleeding.

[0121] [Evaluation of continuous injection property] The ink to be evaluated was introduced into the inkjet head KM1024i (manufactured by Konica Minolta). Specifically, about 10 cc of ink was extruded from the nozzles by pressing at 100 kPa or less. Then, the ink droplets remaining on the nozzle surface were cleaned by the head maintenance described in Table V. After that, a 30-minute continuous discharge test was conducted, and nozzle defects and nozzle bending were observed. Based on the observation results and the following criteria, the continuous injection property was evaluated. The evaluation result of 3 or more is within the allowable range. The evaluation results are as shown in Table V.

[0122] 5: No nozzle defects or nozzle bending occurred. 4: No nozzle defects occurred, but slight nozzle bending occurred. 3: Slight nozzle defects and nozzle bending occurred over time. 2: Nozzle defects and nozzle bending occurred over time. 1: Nozzle defects and nozzle bending occurred from the beginning.

[0123] [Maintainability] After the above continuous discharge test, the ink droplets remaining on the nozzle surface were cleaned by the head maintenance described in Table V. Then, the nozzle plate surface was observed. Based on the observation results and the following criteria, the maintainability was evaluated. The evaluation result of 3 or more is within the allowable range. The evaluation results are as shown in Table V.

[0124] 5: There was no deposit and no wiping trace. 4: There was no deposit, but there was a slight wiping trace at the end of the nozzle plate. 3: There was no deposit, but there was a wiping trace. 2: The adhering matter was on a part of the nozzle plate. 1: The adhering matter was on the entire nozzle plate.

[0125]

Table 5

[0126] In Examples 1 to 23, Comparative Examples 1 to 3, and Comparative Example 6, head maintenance was performed using a wiping mechanism that wipes and cleans the nozzle surface of the inkjet head. In the blade-type head maintenance, the wiping mechanism shown in FIG. 3 was used. In the web-type head maintenance, the wiping mechanism shown in FIG. 4 was used, and a non-woven fabric was used as the web. In the roller-type head maintenance, the wiping mechanism shown in FIG. 2 was used, and a water-absorbent sponge roller was used as the roller. In Comparative Examples 4 and 5, head maintenance was performed using a mechanism that cleans by only pressing the web against the nozzle surface without wiping the nozzle surface with the web.

[0127] From the above results, it was confirmed that the image forming method of the present invention can achieve both the friction fastness of the image and the ejection suitability of the ink.

Explanation of Signs

[0128] 1 Image forming system 2 Belt conveyance device 21 Driving roller 22 Driven roller 23 Conveyance belt 3 Inkjet head 3A Nozzle surface 4 Wiping mechanism 411 Wiping member 412 Reservoir member 412A Rotating shaft 413 Throttling member 42 Blade member 431 Feeding roller 432 Take-up roller 433 Web 434 Sponge member 435 Sponge roller 436 Spring P recording medium

Claims

1. An image forming system using ink, comprising: an inkjet head that discharges the ink onto a recording medium; a wiping mechanism that wipes and cleans the nozzle surface of the inkjet head; wherein the ink contains a silicone resin; wherein the content A of the oily silicone compound in the ink is less than 1000 ppm by mass; an image forming system.

2. The image forming system according to claim 1, wherein the oily silicone compound is cyclotetrasiloxane.

3. The image forming system according to claim 2, wherein the content A of the oily silicone compound in the ink is 1 ppm by mass or more and less than 250 ppm by mass.

4. The image forming system according to claim 1, wherein the content B of the silicone resin in the ink is 0.1% by mass or more.

5. The image forming system according to claim 2, wherein the ratio (A / B) of the content A of the oily silicone compound to the content B of the silicone resin in the ink is less than 0.

06.

6. The image forming system according to claim 1, wherein the ink contains a pigment.

7. The image forming system according to claim 1, wherein the wiping mechanism is of a roller type and has a water-absorbent sponge roller.

8. The image forming system according to claim 1, wherein the recording medium is a fabric.

9. An image forming method using ink, comprising: a step of discharging the ink onto a recording medium by an inkjet head; a step of wiping and cleaning the nozzle surface of the inkjet head by a wiping mechanism; wherein the ink contains a silicone resin; wherein the content A of the oily silicone compound in the ink is less than 1000 ppm by mass; an image forming method. ​ ​ ​ ​ ​ ​ ​

Images