Recording method and recording apparatus

Abstract

The present disclosure aims to provide a recording method and a recording apparatus capable of suppressing occurrence of color unevenness. A recording method includes an ejecting process in which a first ink and a second ink are ejected from a line head having a length of a recording width or more of a recording medium and are attached to the recording medium, the line head has a plurality of unit heads arranged in a direction of the recording width of the recording medium, and has a portion in which a nozzle-to-nozzle distance in a scanning direction of first nozzles that eject the first ink and second nozzles that eject the second ink is different, the first ink and the second ink contain a color material and inorganic oxide particles, and compositions of the color materials are different from each other.

Description

TECHNICAL FIELD

[0001] The present application relates to a recording method and a recording apparatus. BACKGROUND

[0002] An inkjet recording method is capable of recording a high-fineness image with a relatively simple apparatus, and has been rapidly developed in various aspects. Among them, various studies have been made on image quality and the like. For example, in Patent Literature 1, a recording method described below is disclosed: in the case where a recording apparatus provided with a line head is used, a predetermined water-based ink is used with the aim of recording an image in which connection streaks are not conspicuous, and uniformity and color development are excellent.

[0003] PRIOR ART DOCUMENT

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 2017-213799

[0006] However, in such a conventional method, it is known that a color difference occurs depending on the position when the recorded matter is observed in a width direction intersecting the scanning direction. SUMMARY

[0007] The present application is a recording method described below, that is, a recording method provided with an ejection process in which a first ink and a second ink are ejected from a line head having a length of a recording width or more of a recording medium and are attached to the recording medium, wherein the line head has a plurality of unit heads arranged in a direction of the recording width of the recording medium, and has a portion in which a nozzle-to-nozzle distance in a scanning direction of a first nozzle that ejects the first ink and a second nozzle that ejects the second ink is different, the first ink and the second ink contain a color material and inorganic oxide particles, and compositions of the color materials are different from each other.

[0008] The present application is a recording apparatus described below, that is, a recording apparatus provided with a line head having a length of a recording width or more of a recording medium, and a first ink and a second ink, wherein the line head has a plurality of unit heads arranged in a direction of the recording width of the recording medium, and has a portion in which a nozzle-to-nozzle distance in a scanning direction of a first nozzle that ejects the first ink and a second nozzle that ejects the second ink is different, the first ink and the second ink contain a color material and inorganic oxide particles, and compositions of the color materials are different from each other. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is a schematic cross-sectional view of a recording apparatus that can be used in the recording method of the present application.

[0010] Figure 2A is a view showing a nozzle face of an inkjet head having a portion in which a nozzle-to-nozzle distance is different, as a first example.

[0011] Figure 2B Fig. 1B is a view showing a nozzle surface of an inkjet head having a portion in which the nozzle-to-nozzle distance differs.

[0012] Figure 2C Fig. 1C is a view showing a nozzle surface of an inkjet head having a portion in which the nozzle-to-nozzle distance differs.

[0013] Figure 3A Fig. 2A is a view showing a nozzle surface of an inkjet head having no portion in which the nozzle-to-nozzle distance differs.

[0014] Figure 3B Fig. 2B is a view showing a nozzle surface of an inkjet head having no portion in which the nozzle-to-nozzle distance differs.

[0015] Figure 3C Fig. 2C is a view showing a nozzle surface of an inkjet head having no portion in which the nozzle-to-nozzle distance differs.

[0016] Symbol explanation

[0017] 10: line head; 11: nozzle surface; 12: unit head; 12': unit; 12a: first unit head; 12b: second unit head; 13: joint mark; 14: gap; 100: recording apparatus; D1: scanning direction; D2: width direction; L: distance; Lmax: distance; Lmin: distance; M: recording medium. DETAILED DESCRIPTION

[0018] Hereinafter, an embodiment of the present application (hereinafter, referred to as "the present embodiment") will be described in detail as needed with reference to the accompanying drawings, but the present application is not limited thereto, and various modifications can be made within the scope of the gist thereof. Note that, in the drawings, the same symbols are attached to the same elements, and repeated description is omitted. In addition, the positional relationship of up, down, left, right, and the like is based on the positional relationship shown in the drawings unless otherwise specified. Moreover, the dimensional ratio of the drawings is not limited to the ratio shown in the drawings.

[0019] 1. Recording method

[0020] The recording method of the present embodiment is provided with an ejection process in which a first ink and a second ink are ejected from a line head having a length of a recording width or more of a recording medium and are caused to adhere to the recording medium, wherein the line head has a plurality of unit heads arranged in the direction of the recording width of the recording medium, and has a portion in which the nozzle-to-nozzle distance in the scanning direction of the first nozzles that eject the first ink and the second nozzles that eject the second ink differs, the first ink and the second ink contain a color material and inorganic oxide particles, and the compositions of the color materials are different from each other.

[0021] The line head 10 is generally configured by arranging a plurality of unit heads 12 in the width direction (refer to Figure 3A In the portion of the joint mark 13, the recording density is different, and thus the portion is observed as a stripe when the recording article is observed in the width direction. This is because, when the plurality of unit heads 12 are arranged, the positions of the unit heads 12 in the width direction are not accurately aligned, and the nozzle-to-nozzle distance between the unit heads 12 in the width direction is not correct in the joint mark 13.

[0022] As for the stripe of different density in the portion of the joint mark 13, a method of reducing the density unevenness by image processing technology or the like is known.

[0023] This time, the present inventors and others have conducted intensive research, and as a result, it has been found that, in the portion of the joint mark 13, in addition to the stripe caused by the density unevenness, a color difference is sometimes generated. The reason for generating such a color difference is not particularly limited, but it is considered that the main reason is that, when colors are to be formed with a plurality of inks, portions in which the time difference until each ink adheres to the recording medium can be generated are likely to be generated.

[0024] In the portion of the joint mark 13, portions in which the distance Lmin in the scanning direction of the unit head 12a and the unit head 12b is close and portions in which the distance Lmax in the scanning direction of the unit head 12a and the unit head 12b is far are sometimes generated. Figures 2A-2C In this way, if there are portions in which the distance L in the scanning direction of the unit head 12a and the unit head 12b is different, portions in which the time difference from when the ink of the front falls on the recording medium to when the ink of the back falls on the recording medium is different are likely to be generated when viewed in the width direction. Thus, when observed in the width direction, portions in which the color is formed by the ink of the back falling after the penetration of the ink of the front into the recording medium has progressed and portions in which the color is formed by the ink of the back falling before the penetration of the ink of the front into the recording medium has progressed are generated, and it is presumed that this is the main reason for the color difference. In other words, it is presumed that a phenomenon similar to the case in which, between the case in which two kinds of inks are sequentially penetrated into the recording medium to form a color and the case in which the two kinds of inks are simultaneously penetrated into the recording medium to form a color, the colors formed differ due to the difference in the penetration state of the two kinds of inks is generated.

[0025] On the other hand, it is also conceivable to arrange the unit heads 12 in such a way that portions in which the distance Lmin of the unit head 12a and the unit head 12b is close and portions in which the distance Lmax of the unit head 12a and the unit head 12b is far are not generated. Figures 3A-3C However, if this is done, a gap 14 in which no unit head is arranged is likely to exist relatively widely. Thus, if a predetermined number of nozzles is to be ensured on the nozzle face 11 of the line head, the recording head itself has to be designed to be larger, and this also leads to the large size of the recording device.

[0026] In other words, when it is desirable to construct a line head as small as possible, the aforementioned color difference may occur because the distance Lmin between unit heads 12a and unit heads 12b is close, while the distance Lmax between unit heads 12a and unit heads 12b is far. This color difference is particularly likely to occur when it is desirable to miniaturize the size of the line head in the scanning direction.

[0027] Especially in the case of line printers, the aforementioned color differences are particularly noticeable because the ink is applied to the recording material in a single stroke. In the case of serial printers, even if color differences arise due to the printhead structure, these differences become less noticeable because the ink is applied dispersedly over multiple strokes.

[0028] The primary cause of this color difference lies in the varying penetration conditions, and therefore, it cannot be reduced through image processing techniques like those used for uneven concentration. Therefore, in this embodiment, by using inorganic oxide particles to infuse the ink with these particles, the penetration rate of multiple inks is reduced, minimizing the difference in penetration degree in the portions where the distance Lmin between unit heads 12a and 12b is close and the distance Lmax between them is far. In other words, in this embodiment, by using inorganic oxide particles to reduce the penetration rate of multiple inks, even with differences in distance L, a state approaching simultaneous penetration of multiple inks can be achieved.

[0029] Therefore, even when the printhead is constructed to be as small as possible, differences in penetration can be reduced, and chromatic aberration can be minimized when viewing the recorded object in the width direction. The configuration of this embodiment will now be described in detail.

[0030] 1.1. Spraying process

[0031] The ejection process is the following: ejecting first and second inks from a line printhead with a length exceeding the recording width of the recording medium and allowing them to adhere to the recording medium. Figure 1 A schematic cross-sectional view of a recording apparatus that can be used in the recording method of the present invention is shown.

[0032] 1.1.1. Line header

[0033] The line head 10 is a device that has a length of the recording width or more of the recording medium and ejects an ink composition and causes it to adhere to the recording medium M. The inkjet head 10 has a plurality of unit heads 12 arranged in the recording width direction of the recording medium on a nozzle face 11 opposite the recording medium M. The unit head 12 has a nozzle that ejects an ink composition, and the nozzles can also be arranged in a column. A group of nozzles arranged in a column is also referred to as a "nozzle column". The recording medium M is supported by a tape B and is conveyed in a conveyance direction. The tape B is moved in the conveyance direction D1 by a tape roller 20. The recording device can also be provided with an unillustrated paper feed tray, a paper discharge tray, and the like.

[0034] The unit head 12 is only required to have such a nozzle column, and the structure and the like are not limited except in the case of having a nozzle column. A portion in which there is one nozzle column in the line head 10 is one unit head 12. It can also be said that the nozzle column is the unit head 12.

[0035] In the present embodiment, the line head 10 has a portion in which the nozzle-to-nozzle distance in the scanning direction of the first nozzles that eject the first ink and the second nozzles that eject the second ink is different. Thereby, a color difference is generated, and thus the present application is particularly useful.

[0036] In a line system that uses a line head, for example, an inkjet head having a width of the recording width or more of the recording medium is fixed to a recording device. Then, scanning is performed in which the recording medium is moved in a scanning direction (the longitudinal direction of the recording medium, the conveyance direction), and ink droplets are ejected from the nozzles of the inkjet head in conjunction with this movement, thereby recording an image on the recording medium.

[0037] Alternatively, the recording medium is fixed to the recording device. Then, scanning is performed in which an inkjet head having a width of the recording width or more of the recording medium is moved in a scanning direction, and ink droplets are ejected from the nozzles of the inkjet head in conjunction with this movement, thereby recording an image on the recording medium. The scanning direction is the direction of the scanning.

[0038] In such a line system that uses a line head, recording can be performed by one scanning of the line head and the recording medium, and thus an increase in printing speed can be achieved.

[0039] In Figures 2A-2C Examples 1A to 1C of a nozzle face of an inkjet head having a portion in which the nozzle-to-nozzle distance is different are shown. Note that in the present embodiment, a unit head that has first nozzles that eject a first ink is referred to as a first unit head 12a, and a unit head that has second nozzles that eject a second ink is referred to as a second unit head 12b, and when the two are not distinguished, only the unit head 12 is referred to.

[0040] In addition, the following illustrates a manner in which the first unit head 12a ejects a first ink and the second unit head 12b ejects a second ink, but this manner is only an example.

[0041] That is, in the present application, a configuration in which one unit head includes a nozzle that ejects the first ink and a nozzle that ejects the second ink without the distinction between the first unit head and the second unit head can also be included. More specifically, in a case where the unit head includes a plurality of nozzle rows, each nozzle row can be able to eject a different ink composition.

[0042] For example, the first unit head 12a and the second unit head 12b can not be separate components but can be integral components. In addition, the plurality of first unit heads 12a arranged in the width direction and the plurality of second unit heads 12b arranged in the width direction can not be separate components but can be integral components. The plurality of unit heads 12 that constitute the line head can not be separate components but can be integral components.

[0043] In this case, a portion in which there is one nozzle row that ejects the first ink is also the first unit head 12a, and a portion in which there is one nozzle row that ejects the second ink is also the second unit head 12b. That is, the unit head 12 is also a nozzle row.

[0044] In addition, in the drawing, one first unit head 12a has two nozzle rows in the scanning direction, but the number of nozzle rows can be one or more than two, as long as at least one of the nozzle rows is a nozzle row that ejects the first ink. The same applies to the second unit head 12b.

[0045] Figure 2A In the first example 1A described above, the first unit head 12a and the second unit head 12b are formed as one unit 12' in which the two unit heads are arranged in the length direction, and the unit 12' is arranged with a gap 14 in a manner in which the length direction of the unit 12' is parallel to the width direction D2 of the line head. In addition, the positions of the joint marks 13 of the columns of such units 12' are offset in a manner in which the positions of the joint marks 13 do not overlap each other, and a plurality of units 12' are also arranged on the scanning direction side. Note that the columns of units 12' can also be said to be a plurality of columns of units 12' in which the positions of the gaps 14 are offset in a manner in which the positions of the gaps 14 do not overlap each other, and a plurality of units 12' are also arranged on the scanning direction side.

[0046] In Figure 2A In the first example 1A illustrated above, a portion indicated by Lmin in which the first unit head 12a and the second unit head 12b are close to each other in the scanning direction and a portion indicated by Lmax in which the first unit head 12a and the second unit head 12b are far apart from each other in the scanning direction can be generated. Thus, at least a portion in which the nozzle-to-nozzle distance in the scanning direction of the first nozzle that ejects the first ink and the second nozzle that ejects the second ink is different can be generated.

[0047] The Lmin portion and the Lmax portion are inevitably generated at least in a portion other than the joint mark 13.

[0048] The joint mark 13 is a portion in which the positions of the nozzle rows of the two first unit heads 12a or the two second unit heads 12b overlap each other in the width direction. In this manner, the two unit heads 12 are arranged in the width direction with the nozzles of the joint mark 13. The number of nozzles of each of the first unit heads 12 in one joint mark 13 is one or more, and is not limited thereto, and is preferably, for example, 1 to 10.

[0049] The Lmin portion and the Lmax portion are generated in a portion in which the positions of the nozzle rows of the two first unit heads 12a do not overlap each other in the width direction and the positions of the nozzle rows of the two second unit heads 12b do not overlap each other in the width direction.

[0050] The nozzles of the joint mark 13 can perform ejection control using the nozzles of one of the two unit heads 12, using the nozzles of the other unit head 12, or using the nozzles of both unit heads 12.

[0051] For example, by using the nozzles of both unit heads 12, it is possible to reduce density unevenness of the joint mark 13. In this case, the joint mark 13 can be generated with nozzles having different distances between the nozzles if viewed in the nozzle unit.

[0052] In addition, it is also possible to use only the nozzles of one unit head 12 or only the nozzles of the other unit head 12. In this case, the joint mark 13 is the Lmin portion or the Lmax portion.

[0053] In Figure 2A the example shown, the length in the width direction of the joint mark 13, that is, the portion in which the positions of the two first unit heads 12a overlap each other in the scanning direction and the portion in which the positions of the two second unit heads 12b overlap each other in the scanning direction is shorter than in the example of Figure 2B . Thus, it is possible to reduce the number of unit heads 12 required to constitute the line head, and is thus preferable.

[0054] In addition, in the first example 1B described in Figure 2B , the first unit head 12a and the second unit head 12b are formed as one unit 12' in which the two unit heads are arranged in the length direction, and the unit 12' is arranged without a gap in a manner in which the length direction of the unit 12' is parallel to the width direction D2 of the line head. In addition, the column of such units 12' is configured with a plurality of units 12' in which the positions of the joint marks 13 are staggered in a manner in which the positions of the joint marks 13 do not overlap each other in the width direction D2, and is also arranged on the scanning direction side.

[0055] In Figure 2BIn the example 1B shown, a portion denoted by Lmin, where the first unit head 12a and the second unit head 12b are close together in the scanning direction, and a portion denoted by Lmax, where the first unit head 12a and the second unit head 12b are far apart in the scanning direction, can be generated. Thus, at least portions where the distance between the nozzles in the scanning direction differs between the first nozzle ejecting the first ink and the second nozzle ejecting the second ink can be generated.

[0056] exist Figure 2B In the example shown, with Figure 2A Compared to the previous example, the overlapping portions of the two first unit heads 12a and the two second unit heads 12b in the scanning direction are more extensive, and the portion with the joint mark 13 has a longer length in the width direction. Furthermore, gaps 14 are less likely to occur, resulting in excellent strength of the line head, making it a preferred option.

[0057] exist Figure 2C In the described example 1C, the first unit head 12a and the second unit head 12b are formed as a unit 12' arranged in the length direction of the two unit heads, and the unit 12' is arranged in a manner that the length direction of the unit 12' is obliquely intersecting with respect to the width direction D2 of the row head. Figure 2C In this arrangement, there is a gap between adjacent units 12' that are arranged at an angle, but alternatively, adjacent units 12' can be arranged in a way that does not separate the gaps and are adjacent to each other.

[0058] Preferably, the first nozzle group, consisting of a plurality of first nozzles ejecting the first ink, and the second nozzle group, consisting of a plurality of second nozzles ejecting the second ink, are arranged obliquely or parallel to the direction of the recording width. This results in different apparent nozzle densities in the width direction of the entire line printhead, and different numbers of unit printheads required to construct a line printhead with a predetermined width distance.

[0059] If for such Figure 2C For example, the case where it is arranged at an angle relative to the width direction D2, and such as Figure 2A Compared to the case where they are arranged parallel to the width direction D2, even when using a first unit head 12a and a second unit head 12b with the same nozzle density, the nozzle density in the width direction as a whole of the row head is as follows: Figure 2C For example, it is also higher when it is arranged at an angle relative to the width direction D2. That is, as... Figure 2C For example, the nozzle density is increased when one side is arranged at an angle relative to the width direction D2. Therefore, higher recording resolution and superior image quality are preferred. In this case, the distance between the nozzles in the scanning direction is further increased, making the present invention particularly useful.

[0060] On the other hand, in suchFigure 2A In the case where the first unit heads 12a and the second unit heads 12b are arranged in parallel with the width direction D2 as in the example, the number of unit heads required to constitute a line head having a predetermined distance in the width direction becomes small, which is preferable. In addition, it is possible to shorten the length of the line head as a whole in the scanning direction, which is preferable. Thus, it is also possible to further downsize the line head.

[0061] In Figure 2C In the first example 1C shown in FIG. 10, a portion indicated by Lmax in which the first unit heads 12a and the second unit heads 12b are distanced apart in the scanning direction can be generated. In addition, a portion indicated by Lmin in which the first unit heads 12a and the second unit heads 12b are close to each other can be generated. Thus, at least a portion in which the nozzle-to-nozzle distance in the scanning direction differs between the first nozzles that eject the first ink and the second nozzles that eject the second ink can be generated.

[0062] In addition, in order to compare with the inkjet head having a portion in which the nozzle-to-nozzle distance differs, an inkjet head not having a portion in which the nozzle-to-nozzle distance differs is also described. In Figures 3A-3C Examples 2A to 2C of the nozzle surface of the inkjet head not having a portion in which the nozzle-to-nozzle distance differs are shown.

[0063] In Figure 3A In the example 2A shown in FIG. 11, in the joint 13 in the width direction D2, two or more first unit heads 12a are arranged so as to be distanced apart from each other in the scanning direction D1 in a manner of overlapping. In addition, in the joint 13 in the width direction D2, two or more second unit heads 12b are arranged so as to be distanced apart from each other in the scanning direction D1 in a manner of overlapping. Thus, the nozzle-to-nozzle distance L is constant in any portion. In addition, in the joint 13 in which the first unit heads 12a are arranged so as to be distanced apart from each other in the scanning direction D1 in a manner of overlapping, ink can be ejected from any one of the first unit heads 12a.

[0064] For example, in the joint 13 in the drawing, in the case where the nozzles of the first unit heads 12a located above the drawing are used, the nozzles of the second unit heads 12b located above the drawing are used at the same position in the width direction. Alternatively, in the joint 13 in the drawing, in the case where the nozzles of the first unit heads 12a located below the drawing are used, the nozzles of the second unit heads 12b located below the drawing are used at the same position in the width direction. By thus setting, the nozzle-to-nozzle distance L in the scanning direction D1 of the first unit heads 12a and the second unit heads 12b is equal at any position in the width direction.

[0065] In Figures 3A-3C In the example, the joint 13 of the first unit heads 12a and the joint 13 of the second unit heads 12b are positionally aligned in the width direction. In addition, in a portion other than the joint 13, the nozzle-to-nozzle distance is constant.

[0066] Thus, the distance L between the nozzles of the first unit head 12a and the second unit head 12b in the scanning direction Dl can be made equal at any position in the width direction.

[0067] In Figure 3B In the second example 2B shown, the first unit head 12a and the second unit head 12b are formed as one unit 12' in which the two unit heads are arranged in the scanning direction Dl. Also, in the joint 13 in the width direction D2, two or more units 12' are arranged so as to be staggered with respect to each other in the scanning direction Dl. Thus, the distance L between the nozzles is constant at any portion. Also, in the joint 13 in which the first unit heads 12a are arranged so as to be staggered with respect to each other in the scanning direction Dl, ink can be ejected from any one of the first unit heads 12a.

[0068] In Figure 3C In the second example 2C shown, the first unit heads 12a are arranged in the width direction D2 so that the length direction of the first unit heads 12a is obliquely crossed with the width direction D2 of the line head. Also, the second unit heads 12b are arranged in the width direction D2 so that the length direction of the second unit heads 12b is obliquely crossed with the width direction D2 of the line head. Thus, the distance L between the nozzles is constant at any portion. Also, in the joint 13 in which the first unit heads 12a are arranged so as to be staggered with respect to each other in the scanning direction Dl, ink can be ejected from any one of the first unit heads 12a.

[0069] However, in Figures 3A-3C In the second example 2A to the second example 2C shown, in any of the examples, in order to make it so that there is no portion in which the distance between the nozzles differs, it is necessary to provide a gap 14 of a degree equivalent to the gap. Thus, there is a result that the size of the printhead cannot be reduced.

[0070] Note that, for example, in Figure 3A In the control in which ink is ejected from the first nozzle n1 and the second nozzle n2 and the control in which ink is ejected from the first nozzle n3 and the second nozzle n4, in terms of form, the distance between the nozzles of the first nozzle that ejects the first ink and the second nozzle that ejects the second ink differs. However, in the present embodiment, by "the distance between the nozzles of the first nozzle that ejects the first ink and the second nozzle that ejects the second ink differs", it is not meant that the case in which "the distance between the nozzles of the first nozzle that ejects the first ink and the second nozzle that ejects the second ink differs" and the case in which "the distance between the nozzles of the first nozzle that ejects the first ink and the second nozzle that ejects the second ink does not differ" are made to differ by such control. In the present embodiment, by "the distance between the nozzles of the first nozzle that ejects the first ink and the second nozzle that ejects the second ink differs", it is meant that, as Figures 2A-2CAs shown, the structure of the line head in which the nozzle-to-nozzle distance of the first nozzles that eject the first ink and the second nozzles that eject the second ink is different is inevitable regardless of how the control of the ejection is performed.

[0071] In the present embodiment, when the nozzles that actually eject the ink in the recording are taken into account, the first nozzles that eject the first ink and the second nozzles that eject the second ink are different in the nozzle-to-nozzle distance.

[0072] In addition, in the present embodiment, the first nozzles that eject the first ink and the second nozzles that eject the second ink are different in the time difference in which the first ink ejected from the first nozzles and the second ink ejected from the second nozzles land on the recording medium.

[0073] In the portion in which the nozzle-to-nozzle distance is different, the difference (Lmax - Lmin) in the nozzle-to-nozzle distance is preferably 5 mm or more. Or it is preferably 150 mm or less. Further, it is preferably 5 to 100 mm, more preferably 5 to 80 mm, further preferably 10 to 50 mm, and more further preferably 15 to 50 mm. In addition, further, it is preferably 15 to 30 mm, and more preferably 15 to 20 mm.

[0074] When the difference in the nozzle-to-nozzle distance is 5 mm or more, color unevenness is easily generated, and thus the present application is more useful. In addition, when the difference in the nozzle-to-nozzle distance is the above or less, there is a tendency that color unevenness is difficult to be generated.

[0075] In the portion in which the nozzle-to-nozzle distance is long or the portion in which the nozzle-to-nozzle distance is short, the nozzle-to-nozzle distance (Lmax, Lmin) is preferably 5 mm or more, respectively. Or it is preferably 100 mm or less. Further, it is preferably 10 to 50 mm.

[0076] In addition, the difference (Imax - Imim) between the landing time difference (Imax) of the first ink ejected from the first nozzles and the second ink ejected from the second nozzles in the portion in which the distance in the scanning direction of the first nozzles and the second nozzles is long and the landing time difference (Imim) of the first ink ejected from the first nozzles and the second ink ejected from the second nozzles in the portion in which the distance in the scanning direction of the first nozzles and the second nozzles is short is preferably 5 seconds or more. Or it is preferably 100 milliseconds or less. Further, it is preferably 10 to 50 milliseconds, more preferably 15 to 40 milliseconds, and particularly preferably 20 to 30 milliseconds.

[0077] Furthermore, the ink landing time difference (Imax) between the first ink ejected from the first nozzle and the second ink ejected from the second nozzle in the portion with a long nozzle-to-nozzle distance, and the ink landing time difference (Imim) between the first ink ejected from the first nozzle and the second ink ejected from the second nozzle in the portion with a short nozzle-to-nozzle distance, are preferably 5 seconds or more. Or preferably 100 milliseconds or less. Further, preferably 10 to 50 milliseconds, more preferably 15 to 40 milliseconds, and particularly preferably 20 to 30 milliseconds.

[0078] The scanning speed of the recording medium is preferably 1000 mm / s or less, more preferably 800 mm / s or less, and even more preferably 600 mm / s or less. Furthermore, the scanning speed of the recording medium is preferably 50 mm / s or more, more preferably 100 mm / s or more, and even more preferably 300 mm / s or more.

[0079] The faster the scanning speed of the recording medium, the shorter the difference in landing time between the first and second inks, which tends to suppress color difference, but there is a possibility of other problems such as landing position deviation. Furthermore, the slower the scanning speed of the recording medium, the more prone it is to uneven color difference, thus making this invention more useful.

[0080] The nozzle density of the nozzle array in the unit head 12 is preferably 50 npi. Furthermore, it is preferably 1000 npi or less. More preferably, it is 100 to 800 npi, more preferably 200 to 600 npi, and even more preferably 300 to 500 npi.

[0081] Furthermore, it is preferable that the nozzle density in the width direction of the recording device be set to the same range as described above. In such cases... Figure 2C When the printhead is arranged at an angle relative to the width direction D2, as in the example, the nozzle density in the width direction of the recording device is the apparent nozzle density in the width direction. Alternatively, nozzle density refers to the nozzle density of a nozzle array that ejects a particular ink.

[0082] The recording device 100 of this embodiment is not particularly limited as long as it is a device capable of spraying a first ink and a second ink with different compositions of color materials in a single printhead. It may also have a separate printhead 10 for each color such as cyan, magenta, yellow, black, and white. Alternatively, a single printhead 20 may be configured to spray ink compositions of two or more colors.

[0083] As a method of ejecting the ink composition from the nozzle, a method of driving a pressure generating unit to eject the composition filled in a pressure generating chamber of an inkjet head from the nozzle, or a method of ejecting by applying heat energy can be given. Such an ejection method is also called an inkjet method. As a method of applying pressure to the ink composition in the nozzle, there is no particular limitation, and for example, a piezoelectric method of ejecting a droplet of the ink composition using a piezoelectric element, a thermal method of ejecting a droplet by heating can be given.

[0084] 1.1.2. Ink

[0085] The first ink and the second ink are not particularly limited as long as they contain a color material and inorganic oxide particles and the compositions of the color materials are different from each other, and, as needed, can further contain water, a water-soluble organic solvent, a lactam compound, a resin emulsion, a surfactant, a pH adjuster, and the like. By "the compositions of the color materials are different from each other", a case where the colors themselves are different, that is, the types of the color materials contained are different from each other and the colors of the recorded matter obtained when they are attached to a recording medium are different from each other, such as the relationship between cyan and magenta, can be given. Alternatively, a case where the types and the concentrations (contents) of the color materials are different even if the systems of the colors are the same, and the concentrations of the colors of the recorded matter obtained when they are attached to a recording medium are different from each other, such as dark cyan and light cyan, can be given. Either of these cases is acceptable. It is preferable that the colors themselves be different.

[0086] Hereinafter, each component will be described, and, in the case where no particular mention is made, the components exemplified below can be used for both the first ink and the second ink.

[0087] 1.1.2.1. Color material

[0088] As the color material, as long as the compositions of the color materials of the first ink and the second ink are different from each other, there is no particular limitation, and for example, a pigment or a dye can be given. Among them, a pigment is preferable. The color material can be used alone or two or more can be used at the same time.

[0089] It is preferable that one or both of the first ink and the second ink be a color ink. In the case of a color ink, color difference is more likely to occur, and thus the present application is particularly useful.

[0090] The content of the color material is preferably 0.5 to 15% by mass, more preferably 1.0 to 10% by mass, and further preferably 2.0 to 7.0% by mass, based on the total amount of the first ink in terms of solid content. By making the content of the color material within the above range, there is a tendency to further improve color development and clog recovery.

[0091] The content of the color material is preferably 0.5 to 15% by mass, more preferably 1.0 to 10% by mass, and further preferably 2.0 to 7.0% by mass, based on the total amount of the second ink in terms of solid content. By setting the content of the color material within the above range, there is a tendency to further improve the color development and the clogging recovery.

[0092] 1.1.2.1.1. Pigment

[0093] One or both of the first ink and the second ink can contain a pigment as the color material. As the pigment, there is no particular limitation, and for example, the following can be used: organic pigments such as azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, and the like), polycyclic pigments (such as phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, and the like), nitro pigments, nitroso pigments, aniline black, and the like; inorganic pigments such as carbon black (such as furnace black, thermal lamp black, acetylene black, channel black, and the like), metal oxides, metal sulfides, metal chlorides, and the like; extender pigments such as calcium carbonate, talc, and the like.

[0094] The above pigment can be added to the ink as a pigment dispersion liquid obtained by dispersing the pigment in water with a dispersant, or as a pigment dispersion liquid obtained by dispersing a self-dispersing type surface-treated pigment (hereinafter also referred to as "self-dispersing pigment") in which a hydrophilic group is introduced onto the surface of the pigment particle by a chemical reaction, or as a pigment dispersion liquid obtained by dispersing a pigment coated with a polymer (hereinafter also referred to as "resin-dispersed pigment") in water. Among them, it is preferable to contain the self-dispersing pigment. By using the self-dispersing pigment, there is a tendency to further improve the water resistance of the nozzle plate and the intermittent printing stability.

[0095] The pigment and the dispersant that constitute the above pigment dispersion liquid can each be used alone or two or more kinds can be used in combination.

[0096] 1.1.2.1.2. Dye

[0097] As the dye, no particular limitation is imposed, and examples thereof include acid dyes such as C.I. Acid Yellow, C.I. Acid Red, C.I. Acid Blue, C.I. Acid Orange, C.I. Acid Violet, and C.I. Acid Black; basic dyes such as C.I. Basic Yellow, C.I. Basic Red, C.I. Basic Blue, C.I. Basic Orange, C.I. Basic Violet, and C.I. Basic Black; direct dyes such as C.I. Direct Yellow, C.I. Direct Red, C.I. Direct Blue, C.I. Direct Orange, C.I. Direct Violet, and C.I. Direct Black; reactive dyes such as C.I. Reactive Yellow, C.I. Reactive Red, C.I. Reactive Blue, C.I. Reactive Orange, C.I. Reactive Violet, and C.I. Reactive Black; and disperse dyes such as C.I. Disperse Yellow, C.I. Disperse Red, C.I. Disperse Blue, C.I. Disperse Orange, C.I. Disperse Violet, and C.I. Disperse Black. One of the above dyes can be used alone, or two or more of them can be used simultaneously.

[0098] 1.1.2.2. Inorganic Oxide Particles

[0099] As the inorganic oxide particles, no particular limitation is imposed, and examples thereof include silicon dioxide, aluminum oxide, zirconium oxide, titanium dioxide, cerium dioxide, antimony oxide, tin oxide, tantalum oxide, zinc oxide, lead oxide, and indium oxide. Of these, at least one or more selected from the group consisting of silicon dioxide, aluminum oxide, zirconium oxide, titanium dioxide, and cerium dioxide is preferred. By using such inorganic oxide particles, curling of the obtained recording article can be further suppressed, and the stackability can be further improved. Note that the inorganic oxide particles can be used alone or in combination of two or more. The inorganic oxide particles are particles that contain at least inorganic oxide in the particles. Particles composed of inorganic oxide are preferred.

[0100] The inorganic oxide particles can also be particles that have been subjected to surface treatment. For example, silicon dioxide can be subjected to surface treatment with aluminum oxide. As a result, the range of pH in which the silicon dioxide can be stably dispersed is expanded, and the dispersion stability tends to be further improved.

[0101] As such silicon dioxide, commercially available products can also be used, and examples thereof include SI-45P, SI-80, SI-30P, S-40 manufactured by Showa Denko K.K., and Snowtex 20, Snowtex 30P, Snowtex 40, Snowtex O, Snowtex N, Snowtex C manufactured by Nissan Chemical Industries, Ltd. Of the above-mentioned silicon dioxide, SI-45P and / or SI-80 is preferred from the viewpoint of more effectively and reliably exerting the effects of the present application.

[0102] The volume average particle diameter of the inorganic oxide particles contained in the first ink is preferably 150 nm or less, more preferably 100 nm or less, and further preferably 60 nm or less. In addition, the volume average particle diameter of the inorganic oxide particles contained in the first ink is preferably 5 nm or more, more preferably 10 nm or more, and further preferably 15 nm or more. By making the average particle diameter of the inorganic oxide particles 150 nm or less, there is a tendency for the color development and the clog recovery to be further improved. In addition, by making the average particle diameter of the inorganic oxide particles 5 nm or more, there is a tendency for the color unevenness and the stacking property to be further suppressed.

[0103] The volume average particle diameter of the inorganic oxide particles contained in the second ink is preferably 150 nm or less, more preferably 100 nm or less, and further preferably 60 nm or less. In addition, the volume average particle diameter of the inorganic oxide particles contained in the second ink is preferably 5 nm or more, more preferably 10 nm or more, and further preferably 15 nm or more. By making the average particle diameter of the inorganic oxide particles 150 nm or less, there is a tendency for the color development and the clog recovery to be further improved. In addition, by making the average particle diameter of the inorganic oxide particles 5 nm or more, there is a tendency for the color unevenness and the stacking property to be further suppressed.

[0104] The average particle diameter of the inorganic oxide particles can be measured by a particle size distribution measuring device using a dynamic light scattering method as a measurement principle. As such a particle size distribution measuring device, for example, "Zeta Potential-Particle Size-Molecular Weight Measuring System ELSZ2000ZS" (trade name) manufactured by Otsuka Electronics Co., Ltd. can be given. Note that, in the present specification, the "average particle diameter" means the number-based average particle diameter unless otherwise specified.

[0105] The content of the inorganic oxide particles contained in the first ink is preferably 1.0 to 10% by mass, more preferably 1.5 to 8.0% by mass, and further preferably 2.0 to 6.0% by mass, with respect to the total amount of the first ink as a solid content. By making the content of the inorganic oxide particles 1.0% by mass or more, there is a tendency for the color unevenness and the stacking property to be further improved. In addition, by making the content of the inorganic oxide particles 10% by mass or less, there is a tendency for the color development and the clog recovery to be further improved.

[0106] The content of the inorganic oxide particles contained in the second ink is preferably 1.0 to 10% by mass, more preferably 1.5 to 8.0% by mass, and further preferably 2.0 to 6.0% by mass, with respect to the total amount of the second ink as a solid content. By making the content of the inorganic oxide particles 1.0% by mass or more, there is a tendency for the color unevenness and the stacking property to be further improved. In addition, by making the content of the inorganic oxide particles 10% by mass or less, there is a tendency for the color development and the clog recovery to be further improved.

[0107] 1.1.2.3. Water

[0108] It is preferable that one or both of the first ink and the second ink be an aqueous ink. An aqueous ink is an ink containing water as a main solvent component. The content of water in the aqueous ink is preferably 40% by mass or more, more preferably 40 to 98% by mass, relative to the total amount of the ink. It is further preferable that the content of water be 45% by mass or more and 80% by mass or less, more preferably 50% by mass or more and 75% by mass or less, and further preferably 55% by mass or more and 70% by mass or less. By making the content of water 45% by mass or more, even if a portion of the water evaporates, the viscosity of the ink can be suppressed from rising, and there is a tendency for the clog recovery property to be further improved. In addition, by making the content of water 80% by mass or less, there is a tendency for the stacking property to be further improved.

[0109] 1.1.2.4. Water-soluble organic solvent

[0110] It is preferable that one or both of the first ink and the second ink contain a water-soluble organic solvent. By making the ink composition contain a water-soluble organic solvent, there is a tendency for the storage property to be further improved.

[0111] As the water-soluble organic solvent, there is no particular limitation, and examples that can be given include: polyhydric alcohols of three or more, such as glycerol; nitrogen-containing solvents, such as 2-pyrrolidone and N-methylpyrrolidone; glycols, such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, dipropylene glycol, tripropylene glycol, propylene glycol, butylene glycol, pentylene glycol, and 1,2-hexanediol; and glycol monoalkyl ethers, such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and triethylene glycol monomethyl ether. Of these, glycerol is preferable from the viewpoint of the moisturizing effect.

[0112] The content of the water-soluble organic solvent is preferably 0.5 to 25% by mass, more preferably 3.0 to 20% by mass, and further preferably 5.0 to 15% by mass, relative to the total amount of the ink. By making the content of the water-soluble organic solvent within the above range, there is a tendency for the storage property to be further improved.

[0113] 1.1.2.5. Lactam compound

[0114] At least one or both of the first ink and the second ink can contain a lactam compound. By containing a lactam compound, even if the inorganic oxide particles have agglomerated, the resolubility is further improved, and there is a tendency for the clog recovery property to be further improved.

[0115] As the lactam compound, no particular limitation is placed thereon, and examples thereof include 2-pyrrolidone, N-methyl-2-pyrrolidone, 1-(2-hydroxyethyl)-2-pyrrolidone, 3-methoxy-2-pyrrolidone, 3-acetyloxy-2-pyrrolidone, 4-valerolactam, ε-caprolactam, and the like.

[0116] The lactam compound is preferably a water-soluble compound. The water-soluble compound that is a liquid at ordinary temperature among the lactam compounds is also the above-described water-soluble organic solvent.

[0117] The lactam compound is a 3-membered ring or more, preferably a 3- to 9-membered ring, and more preferably a 5- to 8-membered ring.

[0118] The content of the lactam compound contained in the first ink is preferably 1.0 to 10% by mass, more preferably 1.5 to 8.0% by mass, and further preferably 2.0 to 7.0% by mass, relative to the total amount of the first ink. More preferably, it is 4.0 to 6.0% by mass. Alternatively, it is preferably 3.0 to 5.0% by mass, and more preferably 3.0 to 4.0% by mass. By setting the content of the lactam compound within the above range, there is a tendency that the clogging recovery, the degree of reduction in color difference, and the like are further improved.

[0119] The content of the lactam compound contained in the second ink is preferably 1.0 to 10% by mass, more preferably 1.5 to 8.0% by mass, and further preferably 2.0 to 7.0% by mass, relative to the total amount of the second ink. More preferably, it is 4.0 to 6.0% by mass. Alternatively, it is preferably 3.0 to 5.0% by mass, and more preferably 3.0 to 4.0% by mass. By setting the content of the lactam compound within the above range, there is a tendency that the clogging recovery, the degree of reduction in color difference, and the like are further improved.

[0120] 1.1.2.6. Resin emulsion

[0121] A resin emulsion can also be contained. As the resin emulsion, no particular limitation is placed thereon, and examples thereof include (meth)acrylic resin emulsion, polyurethane resin emulsion, and the like. By using such a resin emulsion, there is a tendency that bleeding of the obtained image is further suppressed, and the rub resistance is also further improved. The resin emulsion can be used singly, or two or more kinds thereof can be used simultaneously.

[0122] As the acrylic resin emulsion, no particular limitation is placed thereon, and examples thereof include emulsions in which (meth)acrylic acid, (meth)acrylate, and the like (meth)acrylic monomers are polymerized, and / or emulsions in which (meth)acrylic monomers and other monomers are copolymerized, such as styrene acrylic resin. Among them, anionic acrylic resin particles are preferred.

[0123] As the polyurethane resin emulsion, any resin emulsion having a urethane bond in the molecule can be used without particular limitation, and examples thereof include polyether-based polyurethane resins having an ether bond in the main chain, polyester-based polyurethane resins having an ester bond in the main chain, and polycarbonate-based polyurethane resins having a carbonate bond in the main chain. Among them, a polyurethane resin microparticle having anionicity is preferred.

[0124] The content of the resin emulsion is preferably 0.1 to 7.5% by mass, more preferably 0.3 to 5.0% by mass, and further preferably 0.5 to 3.0% by mass, based on the total amount of the first ink in terms of solid content. By making the content of the resin emulsion 0.1% by mass or more, there is a tendency that bleeding of the obtained image is suppressed and the rub resistance is also improved. In addition, by making the content of the resin emulsion 7.5% by mass or less, there is a tendency that the discharge stability is improved.

[0125] The content of the resin emulsion is preferably 0.1 to 7.5% by mass, more preferably 0.3 to 5.0% by mass, and further preferably 0.5 to 3.0% by mass, based on the total amount of the second ink in terms of solid content. By making the content of the resin emulsion 0.1% by mass or more, there is a tendency that bleeding of the obtained image is suppressed and the rub resistance is also improved. In addition, by making the content of the resin emulsion 7.5% by mass or less, there is a tendency that the discharge stability is improved.

[0126] 1.1.2.7. Surfactants

[0127] Either one or both of the first ink and the second ink can contain a surfactant. As the surfactant, any surfactant can be used without particular limitation, and examples thereof include acetylene diol-based surfactants, fluorine-based surfactants, and silicone-based surfactants.

[0128] As the acetylene diol-based surfactant, any surfactant can be used without particular limitation, but one or more selected from the group consisting of alkylene oxide adducts of 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,4,7,9-tetramethyl-5-decyne-4,7-diol and alkylene oxide adducts of 2,4-dimethyl-5-decyne-4-ol and 2,4-dimethyl-5-decyne-4-ol are preferred. Note that the acetylene diol-based surfactant can be used alone or in combination with two or more.

[0129] As the fluorine-based surfactant, any surfactant can be used without particular limitation, and examples thereof include perfluoroalkyl sulfonate salts, perfluoroalkyl carboxylate salts, perfluoroalkyl phosphate esters, perfluoroalkyl oxirane adducts, perfluoroalkyl betaines, and perfluoroalkyl amine oxide compounds. Note that the fluorine-based surfactant can be used alone or in combination with two or more.

[0130] As the silicone-based surfactant, a polysiloxane-based compound, a polyether-modified organosiloxane, or the like can be exemplified. Note that the silicone-based surfactant can be used singly or in combination of two or more.

[0131] The content of the surfactant contained in the first ink is preferably 0.1 to 5.0% by mass, more preferably 0.1 to 2.0% by mass, and further preferably 0.3 to 1.5% by mass, relative to the total mass of the first ink. By setting the content of the surfactant within the above range, the clogging recovery property tends to be further improved.

[0132] The content of the surfactant contained in the second ink is preferably 0.1 to 5.0% by mass, more preferably 0.1 to 2.0% by mass, and further preferably 0.3 to 1.5% by mass, relative to the total mass of the second ink. Further preferably, it is 0.5 to 1.3% by mass, and more preferably 0.7 to 1.0% by mass.

[0133] By setting the content of the surfactant within the above range, the clogging recovery property tends to be further improved. In addition, it is excellent in color difference reduction and is thus preferred.

[0134] 1.1.2.8. pH adjuster

[0135] As the pH adjuster, there is no particular limitation, and for example, inorganic acids (e.g., sulfuric acid, hydrochloric acid, nitric acid, etc.), inorganic bases (e.g., lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, etc.), organic bases (triethanolamine, diethanolamine, monoethanolamine, tripropanolamine), organic acids (e.g., adipic acid, citric acid, succinic acid, etc.), and the like can be exemplified. Among them, an organic base is preferred. The pH adjuster can be used singly or in combination of two or more.

[0136] The content of the pH adjuster contained in the first ink is preferably 0.1 to 2.0% by mass, more preferably 0.1 to 1.5% by mass, and further preferably 0.1 to 1.0% by mass, relative to the total mass of the first ink. By setting the content of the pH adjuster within the above range, the clogging recovery property tends to be further improved.

[0137] The content of the pH adjuster contained in the second ink is preferably 0.1 to 2.0% by mass, more preferably 0.1 to 1.5% by mass, and further preferably 0.1 to 1.0% by mass, relative to the total mass of the second ink. By setting the content of the pH adjuster within the above range, the clogging recovery property tends to be further improved.

[0138] 1.1.3. Recording medium

[0139] As the recording medium, no particular limitation is imposed, and for example, an absorbent recording medium, a low-absorbent recording medium, or a non-absorbent recording medium can be given. Among them, an absorbent recording medium, a low-absorbent recording medium are preferred, and an absorbent recording medium is more preferred. The higher the absorbency, the more easily the penetration difference caused by the difference in the distance between the nozzles occurs, and thus the present application is particularly useful.

[0140] Here, the "low-absorbent recording medium" or "non-absorbent recording medium" means a recording medium having a water absorption amount of 10 mL / m 2 The following recording medium. This Bristow method is the most popular method as a measuring method of liquid absorption amount in a short time, and is adopted in JAPAN TAPPI as well. The detailed contents of the test method are described in the standard No. 51 "Paper and board - Determination of liquid absorbency - Bristow method" of "JAPAN TAPPI Test Methods 2000 Edition".

[0141] Note that the low-absorbent recording medium means the above water absorption amount of 5 mL / m 2 The above, 10 mL / m 2 The following recording medium. On the other hand, the absorbent recording medium means the above water absorption amount exceeding 10 mL / m 2 The following recording medium.

[0142] As the absorbent recording medium, no particular limitation is imposed, and for example, a general paper such as electrophotographic paper having high permeability of ink composition, an inkjet paper (inkjet exclusive paper having an ink absorption layer composed of silica particles and / or alumina particles, or an ink absorption layer composed of a hydrophilic polymer such as polyvinyl alcohol (PVA) and / or polyvinylpyrrolidone (PVP)) and the like can be given. In addition, cloth can be given.

[0143] As the low-absorbent recording medium, no particular limitation is imposed, and for example, a coated paper having a coating layer for accepting oily ink provided on the surface can be given. As the coated paper, no particular limitation is imposed, and for example, a printing paper such as art paper, coated paper, matte paper and the like can be given.

[0144] As the non-absorbing recording medium, there are no particular limitations, and examples include: plastic films and / or sheets such as polyvinyl chloride, polyethylene, polypropylene, polyethylene terephthalate (PET), polycarbonate, polystyrene, polyurethane, and the like; metal sheets such as iron, silver, copper, aluminum, and the like; or metal sheets and / or plastic films made by vapor deposition of these various metals, alloy sheets such as stainless steel and / or brass, and the like; recording media formed by adhering (coating) plastic films such as polyvinyl chloride, polyethylene, polypropylene, polyethylene terephthalate (PET), polycarbonate, polystyrene, polyurethane, and the like to a paper substrate, and the like.

[0145] 2.2. Conveying Process

[0146] The recording method of the present embodiment can further have a conveying process. In the conveying process, the recording medium is conveyed in a predetermined direction within the recording device. More specifically, the recording medium is conveyed from a paper feeding section to a paper discharge section using a conveying roller and a conveying belt provided within the recording device. In this conveying process, the ink ejected from the inkjet head adheres to the recording medium to form a recorded matter. The conveying can be performed continuously or intermittently.

[0147] 2. Recording Device

[0148] The recording device of the present embodiment is provided with: a line head having a length of at least the recording width of a recording medium; and a first ink and a second ink, wherein the line head has a plurality of unit heads arranged in the direction of the recording width of the recording medium, and has a portion in which the nozzle-to-nozzle distance in the scanning direction of the first nozzles that eject the first ink and the second nozzles that eject the second ink is different, and the first ink and the second ink contain a color material and inorganic oxide particles, and the compositions of the color materials are different from each other.

[0149] The recording device of the present embodiment can further be provided with a conveying unit that conveys the recording medium. The conveying unit is constituted by, for example, a conveying roller and a conveying belt provided within the recording device.

[0150] Examples

[0151] Hereinafter, the present application will be described more specifically using examples and comparative examples. The present application is not limited by the following examples in any way.

[0152] 1. Preparation of Inks

[0153] Each component was added to a mixture tank in the amounts shown in Table 1, mixed and stirred, and then filtered using a 5-μm membrane filter, thereby obtaining the inkjet inks of Examples. Note that the amounts of each component shown in the table represent mass % unless otherwise specified. In the table, the amounts of the inorganic oxide colloid and the pigment dispersion liquid represent the mass % of the solid content.

[0154] Table 1

[0155]

[0156] Table 2

[0157]

[0158] Abbreviations and product ingredients used in Table 1 are as follows:

[0159] Pigment dispersion liquid

[0160] Blue pigment (CAB-O-JET 450C (manufactured by Cabot Corporation))

[0161] Yellow pigment (CAB-O-JET 470Y (manufactured by Cabot Corporation))

[0162] Inorganic oxide particles

[0163] Colloidal silica (Cataloid SI-30 (D50 = 11 nm), manufactured by Nikkan Shoji Kasei Co., Ltd.)

[0164] Colloidal silica (Cataloid SI-45 (D50 = 45 nm), manufactured by Nikkan Shoji Kasei Co., Ltd.)

[0165] Water-soluble organic solvent

[0166] Glycerin

[0167] Triethylene glycol

[0168] Triethylene glycol monobutyl ether

[0169] Triethylene glycol monomethyl ether

[0170] 1,2-Hexanediol

[0171] Lactam compound

[0172] 2-Pyrrolidone

[0173] 1-(2-Hydroxyethyl)-2-pyrrolidone

[0174] ε-Caprolactam

[0175] Resin emulsion

[0176] Styrene acrylic resin emulsion (manufactured by Seiko PMC Co., Ltd., X-436, Tg: 33°C, acid value 33 mgKOH / g)

[0177] Surfactant

[0178] Olfine E1010 (trade name manufactured by Air Products Co., Ltd., acetylenic glycol-based surfactant)

[0179] Surfynol 104 (trade name of Nikken Chemical Industries Co., Ltd., acetylenic glycol-based surfactant)

[0180] Olfine EXP4300 (trade name of Air Products Co., Ltd., acetylenic glycol-based surfactant)

[0181] [pH adjusting agent]

[0182] triethanolamine

[0183] 2. Evaluation

[0184] 2.1. Color unevenness

[0185] The line-type printer equipped with the line-type heads H1 to H4 described in Table 1 was manufactured, and the two kinds of inks described in Table 1 were filled so as to be able to be ejected. The cyan ink was filled in the nozzles (first nozzles) of one nozzle row of the first unit head, and the yellow ink was filled in the nozzles (second nozzles) of one nozzle row of the second unit head.

[0186] Then, the two kinds of inks were recorded in superposition on plain paper (Xerox P paper). Note that each of the inks was recorded in a manner in which dots were attached on each pixel under the conditions that the ink attachment amount was 6 ng / dot and the recording resolution was 600 x 2400 dpi. In addition, the conveyance speed of the recording medium was set to 600 mm / s.

[0187] However, since the nozzle density of the H3 head in the width direction was low, recording was performed at a recording resolution of 300 x 2400 dpi.

[0188] In addition, in Example 11, the conveyance speed of the recording medium was set to 300 mm / s, so that the distance between colors and the like were different from those of Example 1.

[0189] Note that the line-type heads H1 to H4 had the following structures.

[0190] Line-type head H1: had a nozzle face 11 described in Table 1. The apparent nozzle density in the width direction was 600 npi. Figure 2C Line-type head H2: had a nozzle face 11 described in Table 1. The apparent nozzle density in the width direction was 600 npi.

[0191] Line-type head H2: had a nozzle face 11 described in Table 1. The apparent nozzle density in the width direction was 600 npi. Figure 3C Line-type head H2: had a nozzle face 11 described in Table 1. The apparent nozzle density in the width direction was 600 npi.

[0192] Line-type head H3: had a nozzle face 11 described in Table 1. The nozzle density in the width direction was 300 npi. Figure 2A Line-type head H3: had a nozzle face 11 described in Table 1. The nozzle density in the width direction was 300 npi.

[0193] Line head H4: A line head in which the inclination of the nozzle with respect to the width direction is made larger than that of the line head Hl, thereby increasing the difference in nozzle-to-nozzle distance between the first nozzle and the second nozzle.

[0194] Note that in each line head, although the unit head 12 constituting the line head has two nozzle rows in the scanning direction as shown in the drawing, one of the nozzle rows located above the drawing is used. The nozzle density in the width direction of the nozzle row is set to 300 npi, and the number of nozzles of the nozzle row is set to 300. Further, the number of nozzles of one joint 13 is set to five for each of the nozzle rows of the unit heads. Further, in the joint 13, the nozzles that overlap in position in the width direction are alternately used with the nozzles of one unit head 12a and the nozzles of another unit head 12a at the time of recording dots in the scanning direction. By so setting, unevenness in density is reduced.

[0195] Further, in the line head H2, in the case where the first nozzle of the first unit head 12a located below the drawing is used in the joint 13, the second nozzle located in the same position in the width direction of the drawing uses the second nozzle of the second unit head 12b located below the drawing, and in the case where the first nozzle of the first unit head 12a located above the drawing is used, the second nozzle located in the same position in the width direction of the drawing uses the second nozzle of the second unit head 12b located above the drawing. Thus, there is no difference in nozzle-to-nozzle distance in the joint 13 either.

[0196] In Table 3, the difference in color-to-color distance is the difference in nozzle-to-nozzle distance (Lmax - Lmin). Further, the difference in color-to-color time difference is the difference in landing time difference (Imax - Imim).

[0197] In the green portion of the recording material composed of cyan and yellow obtained as described above, the recording material is colorimetrically measured in the portion where the nozzle-to-nozzle distance is long and the portion where the nozzle-to-nozzle distance is short, and the color difference ΔE is calculated. The line head H2 has no portion where the nozzle-to-nozzle distance is long and the portion where the nozzle-to-nozzle distance is short, and thus the colorimetric measurement is performed at an appropriate position.

[0198] Evaluation Criteria

[0199] A: ΔE is less than 2

[0200] B: ΔE is 2 or more and less than 4

[0201] C: ΔE is 4 or more and less than 6

[0202] D: ΔE is 6 or more

[0203] 2.2. Color Development

[0204] In the green portion composed of cyan and yellow of the recording material obtained as described above, the maximum density portion in the width direction D2 was colorimetrically measured using a colorimeter (Xrite i1 manufactured by Xrite Co.), and the OD value of the portion was obtained. Based on the obtained OD value, the color development was evaluated in accordance with the following evaluation criteria.

[0205] Evaluation Criteria

[0206] A: OD value exceeds 1.0

[0207] B: OD value exceeds 0.95 and is 1.0 or less

[0208] C: OD value exceeds 0.90 and is 0.95 or less

[0209] D: OD value is 0.9 or less

[0210] 2.3. Clogging Recovery

[0211] The ink cartridge of the inkjet recording device used in the evaluation of color unevenness was filled with ink, and it was confirmed that ink could be ejected from all the nozzles. Then, the inkjet head was deviated from the position of the cover provided in the printer, and left for seven days in an environment of 40°C without the cover on the head.

[0212] After the standing, as the cleaning of the inkjet head, the number of nozzles that could not eject ink was counted each time the ink suction operation in the nozzles was performed, and the cleaning operation was repeated until all the nozzles were recovered. Then, based on the number of cleanings at the time of recovery of all the nozzles, the clogging recovery was evaluated in accordance with the following evaluation criteria. The results are shown in Table 1.

[0213] Evaluation Criteria

[0214] AA: All recovered after one cleaning

[0215] A: All recovered after 2 to 3 cleanings

[0216] B: All recovered after 4 to 5 cleanings

[0217] C: All recovered after 6 or more cleanings

[0218] 2.4. Stackability

[0219] Using the inkjet recording device used in the evaluation of color unevenness, 20 sheets were continuously printed, and the stackability when discharged on the paper discharge tray was evaluated in accordance with the following evaluation criteria.

[0220] Evaluation Criteria

[0221] A: Aligned like stapler binding (gathered and the ends of the sheets are completely aligned)

[0222] B: Although 20 sheets can be stacked, they are not aligned (the ends of the sheets are not aligned although they are bundled)

[0223] C: 20 sheets cannot be stacked (fly out from the tray)

[0224] Table 3

[0225]

[0226] 3. Evaluation results

[0227] As is apparent from the reference example, in the case of using the line head H2 having a portion in which the distance between the first nozzle that ejects the first ink and the second nozzle that ejects the second ink is different, no problem of unevenness of color difference occurs. On the other hand, it is also apparent that in the line head H2 used in the reference example, the gap is large, and miniaturization cannot be achieved.

[0228] In addition, as is apparent from the comparison between the examples and the comparative example, even in the case of using the head having a portion in which the distance between the first nozzle that ejects the first ink and the second nozzle that ejects the second ink is different, by using the ink composition containing the inorganic oxide particles, unevenness of color difference can be suppressed.

Claims

1. A recording method characterized by comprising a discharging step of discharging and adhering a first ink and a second ink from a line head having a length of a recording width or more of a recording medium to the recording medium, the line head has a plurality of unit heads arranged in a direction of the recording width of the recording medium, and a nozzle-to-nozzle distance in a scanning direction of a first nozzle discharging the first ink and a second nozzle discharging the second ink has a close portion and a distant portion, the nozzle-to-nozzle distance of the close portion being different from the nozzle-to-nozzle distance of the distant portion, in the distant portion, there is no first nozzle discharging the first ink and no second nozzle discharging the second ink between the first nozzle and the second nozzle in the scanning direction, the first ink and the second ink contain a color material and inorganic oxide particles, and compositions of the color material are different from each other, the inorganic oxide particles contained in the first ink and the second ink contain one or more selected from the group consisting of silicon dioxide, aluminum oxide, zirconium oxide, and cerium dioxide.

2. The recording method according to claim 1, characterized in that, in the line head, a first nozzle group constituted by a plurality of the first nozzles discharging the first ink and a second nozzle group constituted by a plurality of the second nozzles discharging the second ink are arranged obliquely or in parallel with respect to the direction of the recording width.

3. The recording method according to claim 1 or 2, characterized in that, a content of the inorganic oxide particles contained in the first ink is 1.0 to 10 mass% with respect to a total amount of the first ink, a content of the inorganic oxide particles contained in the second ink is 1.0 to 10 mass% with respect to a total amount of the second ink.

4. The recording method according to claim 1, characterized in that, a volume average particle diameter of the inorganic oxide particles contained in the first ink is 100 nm or less, a volume average particle diameter of the inorganic oxide particles contained in the second ink is 100 nm or less.

5. The recording method according to claim 1, characterized in that, the first ink contains a lactam-based compound, the second ink contains a lactam-based compound.

6. The recording method according to claim 5, characterized in that, a content of the lactam-based compound contained in the first ink is 1.0 to 10 mass% with respect to a total amount of the first ink, a content of the lactam-based compound contained in the second ink is 1.0 to 10 mass% with respect to a total amount of the second ink.

7. The recording method according to claim 1, characterized in that, the first ink contains a surfactant, the second ink contains a surfactant, a content of the surfactant contained in the first ink is 0.1 to 2.0 mass% with respect to a total amount of the first ink, a content of the surfactant contained in the second ink is 0.1 to 2.0 mass% with respect to a total amount of the second ink. ​ 8. The recording method according to claim 1, wherein the difference in the distance between the nozzles is 5 mm to 80 mm in the portion where the distance between the nozzles is different.

9. The recording method according to claim 1, wherein the scanning speed of the recording medium is 600 mm / s or less.

10. The recording method according to claim 1, wherein the inorganic oxide particles contained in the first ink and the second ink contain one or more selected from the group consisting of silicon dioxide and aluminum oxide.

11. The recording method according to claim 1, wherein the first ink and the second ink are water-based inks.

12. The recording method according to claim 1, wherein the first ink and the second ink are color inks.

13. The recording method according to claim 1, wherein the recording medium is an absorbent recording medium.

14. A recording apparatus characterized by comprising: a recording apparatus that records by the recording method according to claim 1 or 2, the recording apparatus comprising: the line head, the first ink, and the second ink.

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