JP2010208037A - Inkjet recording method and recorder - Google Patents

Abstract

An object of the present invention is to form an image with a plurality of inks including an ink that does not show an effect of improving scratch resistance and glossiness when applied alone, and has high scratch resistance, recording portion and non-recording. PROBLEM TO BE SOLVED: To provide an ink jet recording method and apparatus capable of forming an image exhibiting excellent glossiness that is not different from the part.
When performing recording by an inkjet recording method using a plurality of inks, the first ink includes a pigment, and a graft including a nonionic unit and a unit having a polysiloxane structure with respect to the pigment. In the range of 0.5 to 5.0 times the polymer, the second ink contains a pigment and substantially does not contain the graft polymer. On the other hand, the main scanning of the recording head 101 is repeated for recording, and the application amount of the first ink applied to the unit area in the second half and thereafter is set to 60% or more.
[Selection] Figure 1

Description

  The present invention relates to an ink jet recording method and an ink jet recording apparatus using an ink containing a pigment as a coloring material.

  Ink for ink-jet recording, pigment ink containing pigment as a coloring material has recently been widely used not only for small printers used for office and home applications, but also for large format printers used for printing posters and advertisements. Has been applied. When printing with a large format printer, a fairly large recording medium such as A0 size or A1 size is often used, and when carrying a recording medium on which an image is recorded, it is generally rounded into a cylindrical shape. . For this reason, in the case of an inkjet recording image using a large recording medium, the following problems may occur.

  That is, when the recording medium is rolled, the image may be rubbed with sharp portions such as corners of the recording medium. At this time, the image recorded with the pigment ink is scratched and the color material is scraped off. However, it occurs quite often. Similar problems also occur in other situations. For example, when an image recorded with pigment ink is pasted outdoors as a poster, the image is strongly scratched by a sharp object such as a nail. Also at this time, as described above, the problem that the color material is scraped off occurs frequently. As described above, when pigment ink is selected as the ink to be used in the large format printer and a large image is formed, there is a specific problem to be solved. That is, in the case of a large image by a large format printer, even if a sharp object touches the image, the coloring material of the image is not scraped off, and has a much higher level of scratch resistance than that of a normal image. Realization is a major issue.

  On the other hand, the scratch resistance of images recorded with pigment ink has been a problem so far, and various methods have been proposed to solve the problem. However, many of them are being studied for small printers used for offices and homes, so the scratch resistance of touching an image with a finger is not damaged only by using conventional technology. It is as hard as possible to get. In other words, it still cannot solve the problem of the high level of scratch resistance that occurs when a sharp object touches the image, as required for large images by the large-format printer described above. is there.

  Of course, even in the above situation, there are several proposals regarding a method for obtaining a higher level of image scratch resistance so as to provide an image that can satisfy the scratch resistance. For example, there is a proposal relating to improving the slipperiness of an image and improving the scratch resistance of the image by applying a specific compound on the image recorded with the ink jet ink (see Patent Document 1).

  On the other hand, when recording on a recording medium using pigment ink, there is a problem that a large amount of pigment particles are present on the surface of the recording medium. For example, there are no holes in the ink receiving layer of the swelling type recording medium used for photographic image recording, which is used when creating the above poster, and there are no holes in the ink receiving layer of the void type recording medium. However, the particle size of the pigment is larger than the pore size. Therefore, most of the pigments cannot penetrate into the ink receiving layer of the recording medium and are exposed on the surface of the recording medium. As a result, in the portion of the image recorded with the pigment ink on the recording medium, a new surface is formed by the exposed pigment. Therefore, the smoothness of the surface may differ from the surface of the recording medium depending on the accumulation state of the pigment particles exposed on the recording medium. This difference in smoothness appears as a difference in gloss between the recording portion and the non-recording portion of the recording medium. If there are areas with different glossiness in the recording medium, it will be felt uncomfortable and the glossiness will be uncomfortable.

  As countermeasures against these problems, further finer pigments have been studied in order to eliminate the optical particle properties of pigments (see Patent Document 2). In addition, for the purpose of improving glossiness, a resin, especially a resin emulsion, is added to the ink to improve the smoothness of the surface of the recording medium. (See Patent Documents 3 to 5). Patent Document 6 discloses a technique for improving scratch resistance by further applying a coating liquid after recording an image with colored ink.

JP 2000-108495 A JP 09-176543 A JP 09-208870 A JP 2006-282760 A JP 09-188732 A JP 2005-081754 A

  However, as a result of the study by the present inventors, when an image is recorded using only the ink jet ink, the recorded image is the object of the above-described present invention, regardless of which of the conventional techniques described above is used. It has been found that a much higher level of scratch resistance cannot be satisfied. That is, with the conventional techniques as described above, a satisfactory image can be obtained if the image has a scratch resistance level that does not damage the image even if it is lightly touched with a nail, but a higher level image scratch resistance is obtained. Sex has not been realized. Specifically, when the image is scratched with a sharp object such as a nail by applying a pressure strong enough to damage the non-recording portion of the recording medium, a phenomenon occurs in which the color material is scraped off.

  For example, as described in Patent Document 1, after recording an image, the image is surely captured by using a method of protecting the image later with a so-called solid material such as spraying or applying a lubricant or a sliding compound. If protected, the object of the present invention may be achieved. In addition, when using a laminate method in which an image is covered with a film or the like, the object of the present invention may be achieved as in the invention described in Patent Document 1. However, according to the study by the present inventors, as described in Patent Document 1, when using an ink containing a lubricating substance or when applying an aqueous solution containing a lubricating substance on an image, The lubricating substance penetrates into the recording medium together with the aqueous medium. As a result, in such a case, it was found that the effect of improving the scratch resistance due to the application of these liquids to the image was hardly obtained. Furthermore, Patent Document 5 describes an ink containing a silicone polymer, but does not describe anything about improving the scratch resistance of an image.

  Further, as a method for improving glossiness, a technique for dispersing most pigment particles in ink with a particle diameter of 100 nm or less as described in Patent Document 2 is known. When such a pigment is used for recording on a glossy recording medium, a certain degree of gloss can be obtained as compared with recording using a conventional size pigment. However, even if such fine pigments are used, the glossiness of the image surface is still lacking compared to the case of dyes, so that a clear image has not been obtained. As for the scratch resistance of the image, although it is difficult to transfer the color easily, the pigment particles are still stacked and exposed on the surface of the recording medium. To do.

  Further, as a method for improving glossiness, there is also a disclosure of an invention in which a resin is contained in an ink, in particular, a resin emulsion is added, as described in Patent Document 3. However, when the resin emulsion described in the document was added, the uniformity of gloss was lost and unevenness became noticeable, and no improvement in gloss was observed.

  Further, as a method for improving the glossiness of an image, there is a disclosure of a method of dispersing a pigment using a water-insoluble polymer having a silicone component as a dispersant, as described in Patent Document 4. However, in this case, the pigments slipped by adsorbing the silicone-containing material on the pigment as a dispersant, and this time, the scratch resistance decreased. That is, using a silicone-containing material as a dispersant is not preferable for improving the scratch resistance although an improvement in glossiness is observed. That is, these conventional methods cannot achieve both scratch resistance and glossiness.

  Patent Document 6 discloses a technique for improving the scratch resistance by further applying a coating liquid after recording an image with colored ink. However, depending on the thickness of the film formed by the applied coating liquid, interference fringes may occur due to light interference.

  On the other hand, when recording is performed using a plurality of inks, it is only necessary that all the inks used contain a compound that improves scratch resistance and glossiness. However, from the viewpoints of storage stability and reliability (face surface wetting suppression and ejection stability), all the inks are not allowed to be contained. When recording is performed using a plurality of inks composed of such a combination, there is an area where recording is performed only with ink to which a compound that improves scratch resistance and glossiness is not applied. And this area is not only low in scratch resistance and gloss, but also compared with the area with improved scratch resistance and gloss recorded by the ink with a compound that improves scratch resistance and gloss. Therefore, the low performance is conspicuous.

  Therefore, the object of the present invention is good even when a plurality of inks used for image formation contain an ink that does not exhibit an effect of improving scratch resistance or gloss when applied alone. An inkjet recording method and a recording apparatus capable of forming an image are provided. Specifically, even in the above case, even when a pressure is applied so as to damage the non-recording portion of the recording medium and the recording location is touched, the color material at the recording location is hardly scraped off. It is an object of the present invention to provide a recording method capable of obtaining an image satisfying scratch resistance. In addition, an object of the present invention is to provide a recording method that gives an image satisfying a high level of glossiness without causing a difference between a recording portion and a non-recording portion of a recording medium.

  As a means for solving the above problems, the present inventors use a plurality of inks including a first ink having a new configuration and a second ink different from the first ink, and perform recording by repeating main scanning of the recording head a plurality of times. At this time, it was found that it is effective to control and record the amount of the first ink applied. As a result, an image having sufficient abrasion resistance and glossiness can be obtained. The present invention is achieved by the following means.

（一般式（Ａ）中、Ｒ₁及びＲ₂はそれぞれ独立に水素原子又はメチル基であり、Ｒ₃はエステル結合又はエーテル結合であり、ｘは１又は２である。ただし、Ｒ₂がメチル基の場合、Ｒ₃がエーテル結合となることはない。）

That is, in the present invention, in the inkjet recording method of performing recording on a recording medium by discharging a plurality of inks having the first ink and the second ink by an inkjet recording method, the first ink includes at least A graft polymer comprising a nonionic unit represented by the following general formula (A) and a unit having a polysiloxane structure, and a pigment, and the inclusion of the graft polymer in the ink The amount (mass%) is 0.5 to 5.0 times the content (mass%) of the pigment, the second ink contains at least a pigment, and contains the graft polymer The amount (mass%) is 0.0 times or more and less than 0.2 times the content (mass%) of the pigment, and the inkjet recording method is a unit area of the recording medium. On the other hand, the main scanning of the recording head is repeated n (n is an integer of 2 or more) times to perform recording, and when the first ink is applied to the unit area, the first scanning at the i-th scanning is performed. An ink jet recording method characterized in that the applied amount V (i) of one ink satisfies the following formula [I] or formula [II].

(In the general formula (A), R ₁ and R ₂ are each independently a hydrogen atom or a methyl group, R ₃ is an ester bond or an ether bond, and x is 1 or 2, provided that R ₂ is methyl. In the case of a group, R ₃ is not an ether bond.)

  In another embodiment of the present invention, an ink storage unit for storing a plurality of inks and a recording head for ejecting ink are provided, and recording is performed by the above-described ink jet recording method. An inkjet recording apparatus is provided that is configured as described above.

  The unit area referred to in the present invention means one pixel, one band, and the like, and the unit area can be set as various areas as necessary. One pixel is one pixel corresponding to the resolution, and one band is an image area formed by one scan of the recording head.

  According to the present invention, it is possible to realize the scratch resistance of an image while ensuring the ejection stability and the storage stability of the ink, and far surpassing the scratch resistance that has been recognized as a problem. It is possible to provide an image satisfying the glossiness that is the same between the non-recording portion and the non-recording portion. In other words, the scratch resistance of the image realized in the present invention is that the coloring material at the recording location is almost scraped off even when the recording location is touched with a pressure that is strong enough to damage the non-recording portion of the recording medium. There is no high level, and the whole image is satisfactory. Furthermore, the image obtained by the present invention has little unevenness due to the pigment particles on the outermost surface of the exposed recording part, and the surface smoothness is maintained, and there is no difference in gloss between the recording part and the non-recording part of the recording medium. The entire image satisfies glossiness.

FIG. 3 is a schematic diagram illustrating an example of a recording head. It is a schematic diagram explaining a multipass printing method. It is a figure which shows an example of the mask pattern utilized when performing 4-pass multipass printing. It is a figure showing an example of a mask pattern devised so that D ink may be given to a recording medium at a stage later than other inks as much as possible. It is a figure showing an example of a mask pattern devised so that D ink may be given to a recording medium at a stage later than other inks as much as possible. It is a schematic diagram which shows another example of the head in this invention. It is a schematic diagram showing a state when two types of ink having different physical properties are applied to a recording medium. FIG. 2 is a longitudinal sectional view of a recording head. It is a vertical and horizontal view of a recording head. FIG. 10 is an external perspective view of a head in which the recording head shown in FIG. It is a figure for demonstrating the conceptual structure of an inkjet recording device. It is a figure which shows an example of a structure of an ink cartridge. It is a perspective view which shows an example of a recording unit. FIG. 3 is a diagram illustrating an example of a configuration of a recording head.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments of the present invention.
The point of the present invention is in the following two points. First, a first ink of a plurality of inks that contains a specific graft polymer in a specific amount range with respect to the pigment, and a second ink that does not substantially contain the graft polymer. It is in the point which set it as the structure using this ink. Specifically, the content of the specific graft polymer is substantially contained in the second ink in a range of 0.0 times or more and less than 0.2 times the pigment content (% by mass). Use what you can't say. Hereinafter, the specific graft polymer may be referred to as “silicone graft polymer”. Further, the present invention is characterized in that an image is recorded by a specific recording method that uses the plurality of inks and controls the application amount of the first ink. As a result, it is possible to provide an image with much improved scratch resistance and gloss compared to conventional recording methods even at various recording locations such as various hues and color densities of the image. Hereinafter, the background to the present invention will be described.

  The inventors of the present invention first examined the configuration of an ink that, when used for image formation, more effectively has a recorded image having scratch resistance and glossiness. In the course of the study, for the purpose of improving the scratch resistance of the image, a silicone polymer, which is a material having an effect of improving the slip property of the coating film surface, was used for the ink component. As a result, although the scratch resistance of the image has been improved, since the silicone polymer is highly hydrophobic, aggregation between the silicone polymers occurs on the outermost surface of the recording portion of the recording medium, and an improvement in glossiness is observed. There wasn't.

  Therefore, when further investigation was made, it is effective to use a graft polymer in which a unit composed of a highly hydrophobic siloxane-containing monomer and a unit composed of a specific nonionic monomer having high hydrophilicity are incorporated in the same polymer. I found out. The reason is that the structure is maintained by the microphase separation of each unit. As a result, the image recorded using the ink containing the polymer is slippery on the surface and has leveling properties. It is presumed that the compatibility of glossiness and glossiness has become possible.

  In the present invention, the structure was determined by focusing on the frictional force between the recorded image and the substance in contact with the image in addition to the effect of improving the slip property of the coating film surface in one of the plurality of inks used. One feature is that it is based on a new idea of including a specific graft polymer. First, a polysiloxane-containing monomer is used as a material for forming a silicone graft polymer, thereby including a unit having a polysiloxane structure, which is used as an ink material. As a result of such a configuration, according to the present invention, not only the color material at the recording location is not scraped off even when the recording location is touched by applying a pressure that is strong enough to damage the non-recording portion of the recording medium. It is possible to provide an image with almost no scars. Details of the specific graft polymer will be described later.

  Furthermore, in the present invention, by using a specific nonionic monomer as the forming material, the silicone graft polymer has a nonionic unit in addition to the unit having the polysiloxane structure in the structure of the silicone graft polymer. Used as an ink component. By making the structure of the silicone graft polymer in this way, the hydrophilicity is improved. As a result, when used as an ink component, the resin hardly aggregates on the outermost surface of the recording portion of the recording medium. For this reason, the image formed with the ink containing the graft polymer having such a structure has no irregularities on the outermost surface of the recording portion, and the surface smoothness is maintained. As a result of maintaining smoothness on the surface, it is possible to provide an image satisfying glossiness at a level where there is no difference between the recording portion and the non-recording portion of the recording medium.

  As described above, an object of the present invention is to provide an ink jet recording method for recording an image satisfying a high level of scratch resistance as described above while maintaining gloss in the entire recorded image. is there. According to the study by the present inventors, as one means for achieving this object, all the inks of the plurality of inks used for image formation are changed to inks containing the specific silicone graft polymer described above (first Ink).

  However, according to the study by the present inventors, there are cases where the above-mentioned specific silicone graft polymer cannot necessarily be contained in all of the plurality of inks used for image formation for reasons such as reliability performance and image performance. It has been found. On the other hand, the present inventors do not necessarily need to use all of the plurality of inks used as the first ink having the above-described specific silicone graft polymer depending on the recording method. I found out. The present invention suffices if at least one ink used for recording is an ink containing the above-mentioned specific graft polymer, and the recording method can be used even if the other ink used in combination does not substantially contain the polymer. Based on new knowledge that the above-mentioned purpose can be achieved by devising. Note that the term “substantially free of silicone graft polymer” as used herein means that it is contained only to the extent that the scratch resistance alone is not satisfied when recording using the ink, and is not contained at all. Even if it does not do, the effect of this invention can be acquired without a problem. More specifically, the content (mass%) of the graft polymer is 0.0 times or more and less than 0.2 times the pigment content (mass%) in the ink defined in the present invention. It is within.

（一般式（Ａ）中、Ｒ₁及びＲ₂はそれぞれ独立に水素原子又はメチル基であり、Ｒ₃はエステル結合又はエーテル結合であり、ｘは１又は２である。ただし、Ｒ₂がメチル基の場合、Ｒ₃がエーテル結合となることはない。） The first ink used in the present invention contains a pigment and a specific graft polymer, and the content (mass%) of the graft polymer in the ink is 0.5 times the content (mass%) of the pigment. More than 5.0 times. The specific graft polymer includes at least a nonionic unit represented by the following general formula (A) and a unit having a polysiloxane structure. Details of these will be described later.

(In the general formula (A), R ₁ and R ₂ are each independently a hydrogen atom or a methyl group, R ₃ is an ester bond or an ether bond, and x is 1 or 2, provided that R ₂ is methyl. In the case of a group, R ₃ is not an ether bond.)

The image recording method constituting the present invention includes a first ink containing the specific silicone graft polymer and a plurality of inks having substantially no ink to eject ink onto a recording medium by an inkjet recording method. It has the process to provide. Further, as the ink jet recording method, a method of recording an image by repeating main scanning of the recording head a plurality of times (that is, n times of an integer of 2 or more) for a unit area of the recording medium is used. A typical system for recording by repeating the main scanning of the recording head a plurality of times is a so-called multi-pass recording system. When applying the first ink to the unit area, the application amount V (i) of the first ink at the i-th scanning satisfies the following formula [I] or formula [II]. It is characterized by that.

この結果、前記した構成の異なる複数の顔料インクで記録した記録画像において、その耐擦過性は、記録媒体の非記録部に傷が付く程の強い圧力を加えて記録箇所に触れた場合でも、記録箇所の色材が削り落ちることがない高いレベルを満足したものとなる。 As described above, in the formula [I] or the formula [II], the application amount of the first ink to the unit area is set so that the application amount of the first ink in the second half or later scanning is 60% or more. It is prescribed to do. More preferably, as shown in the following formula [III] or [IV], the applied amount of the first ink is 70% or more, and further, the first ink as shown in the following formula [V] or [VI]. The amount of ink applied should be 80% or more.

As a result, in a recorded image recorded with a plurality of pigment inks having different configurations as described above, the scratch resistance is such that even when a recording location is touched by applying a pressure that is strong enough to scratch the non-recording portion of the recording medium, Satisfies a high level in which the color material at the recording location is not scraped off.

  In the case where an image is formed with a plurality of inks including the first ink and the second ink, the first ink is applied using the above-described recording method. The effect of the ink of 1 can be expressed without impairing. The effect of the present invention can be obtained even when a pigment ink using a pigment as a color material, a dye ink using a dye as a color material, or an ink using a combination of these color materials is used as the second ink. . That is, the second ink is not particularly limited as long as it satisfies that the second ink does not substantially contain the silicone graft polymer described above, and may have any configuration. In the present invention, a plurality of inks corresponding to the first ink may be used, or a plurality of inks corresponding to the second ink may be used.

As described above, multi-pass recording is suitable as the recording method used in the present invention. In multi-pass printing, image data that can be printed in one printing scan is thinned out using a mask pattern prepared in advance, and the image is completed step by step by multiple printing main scans, allowing control of printing dots. It becomes. Hereinafter, this point will be described.
FIG. 1 shows an example of a recording head when four types of ink (A, B, C, and D inks) are used, and FIG. 2 is a schematic diagram for simply explaining a multipass recording method. Here, the recording head 101 is used and an image is recorded on the recording medium 201 by four-pass multi-pass recording. During each recording main scan, the recording medium 201 is conveyed in the sub-scanning direction by an amount corresponding to ¼ of the recording width of the recording head 101 (indicated by d in the figure). In such a recording method, the same image area of the recording medium 201 is completed by four recording main scans corresponding to the four areas 1 to 4 of the recording head. As a result, since the plurality of dots arranged in the main scanning direction on the recording medium are recorded by four different nozzles, the variation in nozzle units is alleviated and the entire image becomes smooth. Even when bidirectional recording is performed, ink is applied to all the image areas of the recording medium 201 by both forward scanning and backward scanning, so that the order of ink application to the recording medium may be different for each unit area. The color unevenness of the entire image is suppressed to some extent.

  FIG. 3 is a diagram showing an example of a mask pattern used when performing 4-pass multi-pass printing as shown in FIG. Here, for simplicity, a nozzle row 301 for one color and mask patterns 302a to 302d corresponding to the nozzle row 301 are shown. The nozzles in the nozzle array 301 are divided into four areas, and the nozzles included in the respective areas apply ink by dot arrangement according to the mask patterns 302a to 302d corresponding to the respective areas for recording. Each of the mask patterns 302a to 302d is composed of a plurality of pixel areas in which recording / non-recording is determined by dot arrangement. In the figure, black areas indicate pixels that allow printing by dot arrangement, and white areas show pixels that do not allow printing by dot arrangement. The four types of mask patterns 302a to 302d maintain a complementary relationship with each other. By taking the logical product of these mask patterns and image data in each recording scan, ink by dot arrangement that is actually recorded in each recording main scan is obtained. Is determined. Here, for the sake of simplicity, a mask pattern having an area of 4 pixels × 3 pixels is shown, but an actual mask pattern has a larger area in both the main scanning direction and the sub-scanning direction.

  If such a multi-pass printing method is employed, the printing rate of each area of the mask pattern can be made different for each type of ink even when a printing head having a side-by-side configuration is used. Further, the order of ink application to the recording medium can be controlled to some extent as in a vertically arranged recording head, and a recording method for performing suitable image recording in the present invention is possible.

  In order to obtain the maximum effect of the present invention, a method of applying the first ink to the slowest possible stage using multi-pass is suitable. By recording in this way, the effect of the present invention can be further easily obtained because the surface layer portion of the recorded image to which the silicone graft polymer contained in the first ink is applied, and the portion close to the outermost layer easily remain. .

  Here, the reason why the image formed by the first ink containing the silicone graft polymer has high scratch resistance is that the resin exhibits slipperiness while forming a somewhat strong film (ink layer) with the resin. It is thought that it was achieved by doing. Such an effect cannot be obtained by other methods. That is, a method of imparting slipperiness in another form, for example, when a certain type of yellow pigment is arranged on the surface of the ink layer, the pigment surface layer is slightly detached because the binding force of the pigment on the surface is small, Apparent slipperiness appears to appear. However, such means cannot provide high scratch resistance as in the present invention.

  FIG. 4 is a diagram showing an example of a mask pattern devised so as to apply only the D ink of the four types to the recording medium at a stage as late as possible with the other inks. Reference numeral 401 denotes a nozzle row of A ink, B ink, or C ink, which records an image according to mask patterns 403a to 403d. On the other hand, the nozzle row 402 of D ink records an image according to the mask patterns 404a to 404d. By preparing such a mask pattern in advance, for A ink, B ink, and C ink, an image is recorded in three main recording scans of 33.3% each, and in the last fourth time, the D ink is recorded. 100% recording is performed. As a result, the ratio of the D ink applied after the other A, B, and C inks are applied increases.

  However, in the above mask pattern, since the ink of D is applied only the fourth time, it is recorded only by the nozzles included in the region 4, and the multi-pass recording in which the variation of the entire nozzles is reduced and the entire image is smoothed. There is a possibility that the original advantages cannot be fully utilized. Also, the second ink becomes smoother when it is recorded with as many scans as possible. For example, even if the second ink is applied up to the fourth time, if the first ink is applied only in the second half, the ratio of the first ink remaining in the surface layer portion becomes high, so the object of the present invention is Can be achieved. FIG. 5 shows an example of the mask pattern having such a configuration. A ink, B ink, or C ink records images according to mask patterns 503a to 503d, and D ink records images according to mask patterns 504a to 504d. By using such a mask pattern, for A ink, B ink, and C ink, an image is recorded in four main recording scans of 25%, and 50% of D ink is recorded in the second half. Done at the same time. As a result, as in the case where the mask pattern of FIG. 4 is used, the ratio of the D ink applied after the other A, B, and C inks are applied increases.

  As described above, by preparing mask patterns used in multi-pass printing in advance for various purposes, even in an ink jet recording apparatus using a recording head having a side-by-side configuration, the order of ink application to the recording medium can be set. It is possible to control appropriately. In addition, such a situation can also be applied to image recording by multiple recording principals such as 6-pass, 8-pass, and 12-pass, depending on the mask pattern and the number of multi-pass passes (recording main scan).

  In order to obtain the effect of the present invention, the number of dots applied in the latter half of the total applied amount of the first ink needs to be 60% or more in the multipass printing scan. In this way, by applying the first ink concentrated in the latter half, the first ink is likely to remain on the surface layer portion, compared to the case where the first ink is applied evenly, and the effect of the silicone graft polymer is obtained. As a more preferable form, the effect of the present invention can be obtained more when the applied amount of the first ink in the latter half is 70% or more, and further 80% or more.

  FIG. 6 shows another example of a recording head when four types of ink (A, B, C, D ink) are used. Here, the nozzle row A, nozzle row B, nozzle row C, and nozzle row D are arranged on the recording head 601 in one row in the sub-scanning direction so as not to overlap each other. In such a vertical arrangement, ink of each color is applied to different areas of the recording medium in one main recording scan of the recording head. As a result, regardless of whether the recording head 601 performs the recording main scan in the forward direction or the backward direction, the order in which the ink is applied to the recording medium is in the order of D → C → B → A. For example, an image of a secondary color expressed by a mixture of B and C is always given ink in the order of C → B. Even with such a recording head configuration, it is possible to perform ink application in consideration of the order of ink application as described above without performing particularly difficult control. That is, when it is desired to consider the order of ink application as described above, particularly difficult control is performed if a nozzle row for ejecting ink to be applied with a delay is arranged on the most downstream side in the sub-scanning direction. Even without this, images can be recorded in the desired ink application sequence.

  Up to here, regarding the form of a recording method using a recording apparatus capable of obtaining the effect of the present invention so that the silicone graft polymer contained in the first ink remains on the surface layer portion of the formed recorded image. explained. However, the effect of the present invention becomes more conspicuous by defining the basic physical properties of a plurality of inks to be used as follows, and details of this point will be described.

  The lower the surface tension of the ink, the faster the penetration into the recording medium and the faster the ink is fixed. Considering this point, if the surface tension of the second ink is configured to be 3 mN / m or more lower than the surface tension of the first ink, the following behavior is exhibited, so the effect of the present invention is more remarkable. Therefore, it is preferable. As shown in FIG. 7, in this case, even if the first inks 701a and 701b and the second ink 702 are simultaneously applied, the second ink penetrates and fixes to the recording medium 703 earlier, and Then, one ink permeates slowly thereafter. For this reason, the silicone graft polymer contained in the first ink remains in the surface layer portion of the recorded image. The surface tension of the plurality of inks used in the present invention is preferably 20 mN / m or more and less than 60 mN / m from the viewpoint of ejection performance. A more preferable form is 25 mN / m or more and less than 50 mN / m.

  Another form includes adjusting the water content of the ink. The smaller the amount of water in the ink, the shorter the time from application to the recording medium until fixing. According to a detailed study, it has been found that the water content of the second ink is preferably 10% or more lower than the water content of the first ink. As in the case of the surface tension described above, in this case, the second ink is fixed faster than the first ink and the first ink is slowly fixed later, as shown in FIG. It will remain in the surface layer part. The effect of the present invention can be obtained more remarkably by using the plurality of inks adjusted as described above at the same time as performing recording by the above-described recording method using multi-pass.

<Inkjet recording apparatus>
The basic configuration of an example of the ink jet recording apparatus of the present invention will be described below. First, an example of the configuration of the head, which is the main part of an ink jet recording apparatus using thermal energy, is shown in FIGS. 8 is a cross-sectional view of the head 13 along the ink flow path, and FIG. 9 is a cross-sectional view taken along the line AB of FIG. The head 13 is obtained by adhering a heating element substrate 15 and a glass, ceramic, silicon or plastic plate having a flow path (nozzle) 14 through which ink passes. The heating element substrate 15 includes a protective layer 16, electrodes 17-1 and 17-2 made of aluminum, gold, aluminum-copper alloy, the heating resistor layer 18, the heat storage layer 19, silicon, aluminum, aluminum nitride, etc. It consists of the board | substrate 20 formed with a material with good heat dissipation. The protective layer 16 is formed of silicon oxide, silicon nitride, silicon carbide, or the like, and the heat storage layer 19 is formed of a high melting point material such as HfB ₂ , TaN, or TaAl. In image formation, ink is ejected as follows.

  When a pulsed electric signal is applied to the electrodes 17-1 and 17-2 of the head 13, the region indicated by n of the heating element substrate 15 rapidly generates heat, and bubbles are generated in the ink 21 in contact with the surface. Will occur. Then, the meniscus 23 protrudes by the pressure, the ink 21 is ejected through the nozzle 14 of the head, becomes an ink droplet 24 from the ejection orifice 22, and flies toward the recording medium 25.

  FIG. 10 shows an external view of an example of a multi-head in which a large number of heads shown in FIG. 9 are arranged. This multi-head is made by adhering a glass plate 27 having multi-nozzles 26 and a heat-generating head 28 similar to that described in FIG.

  FIG. 11 is a diagram for explaining the external configuration of the ink jet recording apparatus used in the present embodiment. A carriage 1101 mounted with an ink jet recording head and ink tanks for a plurality of colors reciprocates in the main scanning direction using a carriage motor 1102 as a drive source. A flexible cable 1113 attached to follow the reciprocating scanning of the carriage 1101 transmits and receives electrical signals between a control unit (not shown) and a recording head mounted on the carriage 1101. The movement position of the carriage 1101 can be detected by optically reading an encoder 1106 provided extending in the main scanning direction by an encoder sensor provided on the carriage.

  When a recording operation command is input from a host device connected to the outside, one of the recording media stacked on the paper feed tray 1105 is fed to a recordable position by a recording head mounted on the carriage 1101. . Thereafter, a plurality of recording main scans of the recording head while ejecting ink in accordance with the recording signal and a predetermined amount of conveying operation of the recording medium are alternately repeated to sequentially form images on the recording medium.

  At the end of the area where the carriage 1101 moves, there is a recovery means 1104 for executing print head maintenance processing. The recovery unit 1104 includes a cap 1109 for protecting the discharge port surface of the recording head when sucked and left, a discharge receiver 1107 for receiving the coating liquid at the time of recovery of discharge, a discharge receiver for receiving the ink discharged at the time of recovery of recovery, etc. Is provided. The wiper blade 1110 wipes the ejection port surface of the recording head while moving in the direction of the arrow.

  FIG. 12 is a diagram illustrating an example of an ink cartridge that contains ink supplied to the recording head via an ink supply member, for example, a tube. Here, reference numeral 40 denotes an ink container, for example, an ink bag, in which supply ink is stored, and a rubber plug 42 is provided at the tip thereof. By inserting a needle (not shown) into the stopper 42, the ink in the ink bag 40 can be supplied to the head. An ink absorber 44 receives waste ink. The ink container preferably has a liquid contact surface made of polyolefin, particularly polyethylene.

  The ink jet recording apparatus used in the present invention is not limited to the one in which the head and the ink cartridge are separated as described above, and is suitably used for those in which they are integrated as shown in FIG. . In FIG. 13, reference numeral 70 denotes a recording unit, in which an ink storage portion that stores ink, for example, an ink absorber, is stored. The ink in the ink absorber is transferred from the head portion 71 having a plurality of orifices. It is configured to be ejected as ink droplets. The material of the ink absorber is preferably polyurethane. Alternatively, a structure in which the ink container is an ink bag with a spring or the like inside without using an ink absorber may be used. Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the cartridge with the atmosphere. The recording unit 70 is detachable from the carriage 1101 shown in FIG.

  Next, a basic configuration of a recording apparatus using mechanical energy, which is another example of the ink jet recording apparatus of the present invention, will be described. In this apparatus, a nozzle forming substrate having a plurality of nozzles, a pressure generating element made of a piezoelectric material and a conductive material disposed to face the nozzles, and ink filling the periphery of the pressure generating element are provided. An on-demand ink jet recording head that displaces the pressure generating element by the applied voltage and discharges a small droplet of ink from the nozzle is provided. FIG. 14 shows an example of the configuration of a recording head which is a main part of the recording apparatus.

  The recording head is joined to an ink flow path 80 communicating with an ink chamber (not shown), an orifice plate 81, a vibration plate 82 that directly applies pressure to ink, and the vibration plate 82, and is displaced by an electric signal. A piezoelectric element 83 and a substrate 84 are included. The substrate 84 is for supporting and fixing the orifice plate 81, the vibration plate 82, and the like. The ink flow path 80 is formed of a photosensitive resin or the like. The orifice plate 81 is for ejecting ink droplets of a desired volume, and the ejection port 85 is formed by drilling holes in a metal such as stainless steel or nickel by electroforming or pressing. The diaphragm 82 is formed of a metal film such as stainless steel, nickel, or titanium and a highly elastic resin film, and the piezoelectric element 83 is formed of a dielectric material such as barium titanate or PZT. The recording head configured as described above operates as follows to perform recording. First, a pulse-like voltage is applied to the piezoelectric element 83 to generate a strain stress, and the energy deforms the vibration plate bonded to the piezoelectric element 83, and the ink in the ink flow path 80 is pressurized vertically to form an ink droplet ( Recording is performed by ejecting (not shown) from the ejection port 85 of the orifice plate 81. Such a recording head is used by being incorporated in an ink jet recording apparatus similar to that shown in FIG. The detailed operation of the ink jet recording apparatus can be performed in the same manner as described above.

Next, the silicone graft polymer constituting the first ink that makes it possible to achieve high scratch resistance, which is the object of the present invention, will be described in detail.
(Silicone graft polymer)
The first ink used in the present invention is characterized by containing a graft polymer including a nonionic unit represented by the following general formula (A) and a unit having a polysiloxane structure. In the present invention, hereinafter, “unit” includes both cases in which one or a plurality of repeating units are included in the unit.

（一般式（Ａ）中、Ｒ₁及びＲ₂はそれぞれ独立に水素原子又はメチル基であり、Ｒ₃はエステル結合又はエーテル結合であり、ｘは１又は２である。ただし、Ｒ₂がメチル基の場合、Ｒ₃がエーテル結合となることはない。）

(In the general formula (A), R ₁ and R ₂ are each independently a hydrogen atom or a methyl group, R ₃ is an ester bond or an ether bond, and x is 1 or 2, provided that R ₂ is methyl. In the case of a group, R ₃ is not an ether bond.)

  The graft polymer in the present invention is “a polymer having a structure in which a branch polymer (side chain) is bonded to one trunk polymer (main chain)”. And as a method of discriminating whether the structure of a certain polymer is a graft polymer, the following methods are mentioned, for example. That is, it is possible to determine that the structure of a certain polymer is a graft polymer by measuring the absolute molecular weight and the molecular size in combination with gel permeation chromatography and a multi-angle light scattering detector. Specifically, the greater the difference between the absolute molecular weight and molecular size measured by these methods, the higher the degree of branching of the polymer, and in the form of a graft polymer. Judgment can be made.

Hereinafter, each unit constituting the graft polymer used in the present invention will be described in more detail.
(Nonionic unit)
The nonionic unit constituting the graft polymer used in the first ink has a structure represented by the following general formula (A). The nonionic unit having this structure is obtained by copolymerization of a monomer represented by the following general formula (A ′) having 1 or 2 repeating units of an ethylene oxide group and having a polymerizable functional group at the terminal. is there.

（一般式（Ａ）中、Ｒ₁及びＲ₂はそれぞれ独立に水素原子又はメチル基であり、Ｒ₃はエステル結合又はエーテル結合であり、ｘは１又は２である。ただし、Ｒ₂がメチル基の場合、Ｒ₃がエーテル結合となることはない。）

(In the general formula (A), R ₁ and R ₂ are each independently a hydrogen atom or a methyl group, R ₃ is an ester bond or an ether bond, and x is 1 or 2, provided that R ₂ is methyl. In the case of a group, R ₃ is not an ether bond.)

（一般式（Ａ’）中、Ｒ₁及びＲ₂はそれぞれ独立に水素原子又はメチル基であり、Ｒ₃はエステル結合又はエーテル結合であり、ｘは１又は２である。ただし、Ｒ₂がメチル基の場合、Ｒ₃がエーテル結合となることはない。）

(In general formula (A ′), R ₁ and R ₂ are each independently a hydrogen atom or a methyl group, R ₃ is an ester bond or an ether bond, and x is 1 or 2, provided that R ₂ is In the case of a methyl group, R ₃ does not become an ether bond.)

  In the present invention, the number of repeating units of the ethylene oxide group in the nonionic unit represented by the general formula (A) is 1 or 2, that is, x in the general formula (A) is 1 or 2. Use something. When x in the general formula (A) is 3 or more, in the case where the nonionic unit is included in the main chain, there is a greater tendency for the portion having nonionic properties to be localized and the graft polymer as a whole. Therefore, the water resistance of the image cannot be sufficiently obtained. Further, as described above, when the hydrophilicity of the graft polymer as a whole becomes high, the graft polymer has an action like a surfactant in the ink. In this case, the permeability of the graft polymer into the recording medium of the graft polymer is increased, and the amount of the graft polymer that is oriented on the outermost surface of the image is reduced, so that sufficient image scratch resistance cannot be obtained. .

  Specific examples of the nonionic unit represented by the general formula (A) include those obtained by copolymerization of (meth) acrylate monomers and vinyl ether monomers. Moreover, in the graft polymer used in the present invention, the nonionic unit may be composed of one kind or a combination of two or more kinds.

  Examples of (meth) acrylate monomers include the following. 2-hydroxyethyl methacrylate, diethylene glycol monomethacrylate, 2-hydroxyethyl acrylate. Diethylene glycol monoacrylate, methoxydiethylene glycol monomethacrylate, methoxydiethylene glycol monoacrylate and the like. As such a (meth) acrylate monomer, for example, commercially available products such as BLEMMER PE-90, AE-90, PME-100 (above, NOF Corporation), BHEA, HEMA (manufactured by Nippon Shokubai Co., Ltd.) are used. it can.

  Examples of vinyl ether monomers include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, and the like. As such a vinyl ether monomer, for example, commercially available products such as HEVE and DEGV (manufactured by Maruzen Petrochemical Co., Ltd.) can be used. In the present invention, among these monomers, it is particularly preferable to use 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, or methoxydiethylene glycol-monomethacrylate.

(Unit having polysiloxane structure)
The unit having a polysiloxane structure constituting the graft polymer used in the first ink may be any unit as long as it has a polysiloxane structure. In the present invention, among the units having a polysiloxane structure, it is particularly preferable to use a unit represented by the following general formula (B). The unit represented by the general formula (B) is obtained by copolymerization of a monomer represented by the following general formula (B ′). Moreover, in the graft polymer used in the present invention, the unit having a polysiloxane structure may be constituted by one kind or a combination of two or more kinds.

（一般式（Ｂ）中、Ｒ₈は水素原子又はメチル基であり、Ｒ₉は炭素数１乃至６のアルキレン基であり、Ｒ₁₀はそれぞれ独立にメチル基又はフェニル基であり、Ｒ₁₁は炭素数１乃至６のアルキル基、又はフェニル基であり、ｍは１乃至１５０の整数である。）

(In the general formula (B), R ₈ is a hydrogen atom or a methyl group, R ₉ is an alkylene group having 1 to 6 carbon atoms, R ₁₀ is independently a methyl group or a phenyl group, and R ₁₁ is (It is a C1-C6 alkyl group or a phenyl group, and m is an integer of 1-150.)

（一般式（Ｂ’）中、Ｒ₈は水素原子又はメチル基であり、Ｒ₉は炭素数１乃至６のアルキレン基であり、Ｒ₁₀はそれぞれ独立にメチル基又はフェニル基であり、Ｒ₁₁は炭素数１乃至６のアルキル基、又はフェニル基であり、ｍは１乃至１５０の整数である。）

(In the general formula (B ′), R ₈ is a hydrogen atom or a methyl group, R ₉ is an alkylene group having 1 to 6 carbon atoms, R ₁₀ is independently a methyl group or a phenyl group, R ₁₁ Is an alkyl group having 1 to 6 carbon atoms or a phenyl group, and m is an integer of 1 to 150.)

  In the present invention, as the monomer represented by the general formula (B ′), for example, commercially available products such as Silaplane FM-0711, FM-0721, FM-0725 (manufactured by Chisso) and the like are used. it can.

(Other units)
The graft polymer used for the first ink has at least a nonionic unit represented by the above general formula (A) and a unit having a polysiloxane structure represented by, for example, the general formula (B). is required. However, in addition to these units, another unit may be included. In the present invention, it is particularly preferable that the main chain of the graft polymer has a structure having a nonionic unit represented by the general formula (A) and other units.

  Examples of other units include acid monomers, monomers having a carboxyl group, unsaturated sulfonic acid monomers, unsaturated phosphoric acid monomers, and copolymers of monomers such as anhydrides, salts, and ester compounds thereof. Moreover, in the graft polymer used in the present invention, the other units may be configured by combining one type or two or more types.

  Specific examples of the monomer constituting the other unit include the following monomers. For example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, 2-methacryloyloxymethyl succinic acid and the like. Acrylic esters such as methyl acrylate, ethyl acrylate, and butyl acrylate. Methacrylic acid esters such as methyl methacrylate, methyl methacrylate and butyl methacrylate. Styrene sulfonic acid, maleic anhydride, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acrylic acid ester, bis- (3-sulfopropyl) -itaconic acid ester and the like. Vinylphosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-methacryloyloxyethyl phosphate, and the like. Further, dibutyl-2-acryloyloxyethyl phosphate, dibutyl-2-methacryloyloxyethyl phosphate, dioctyl-2- (meth) acryloyloxyethyl phosphate, and the like. Among these, acrylic acid, methacrylic acid, methyl acrylate, butyl acrylate, methyl methacrylate, and butyl methacrylate are preferable.

  In order to achieve the object of the present invention, the content (% by mass) of the graft polymer in the first ink based on the total mass of the ink is preferably 0.50% by mass or more. More preferably, it is 1.0 mass% or more and less than 20.0 mass%. That is, when the content (% by mass) in the first ink is lower than 0.50% by mass, the absolute amount of the silicone portion oriented on the outermost surface of the recording portion is reduced, so that the formed image has high scratch resistance. May not be satisfied. On the other hand, when the amount exceeds 20.0% by mass, the absolute amount of the silicone portion increases, so that the silicone graft polymer penetrates into the recording portion as well as the silicone is oriented on the outermost surface of the recording portion. However, high scratch resistance may not be satisfied. That is, in this case, it is presumed that the pigments slip due to adsorption of silicone to the pigment, and as a result, the scratch resistance may be lowered.

<Dispersant>
In the present invention, any resin (dispersant) for dispersing the pigment in the ink can be used as long as it is a water-soluble resin. Specifically, a block, random, graft or the like synthesized from at least two monomers (of which at least one is a hydrophilic monomer) selected from the following monomers and derivatives thereof. Examples thereof include polymers and salts thereof. As the monomer, the following can be preferably used. For example, styrene, styrene derivatives, vinyl naphthalene, vinyl naphthalene derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acid, and the like. Acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, fumaric acid derivatives, vinyl acetate, vinylpyrrolidone, acrylamide and the like. Also, natural resins such as rosin, shellac and starch. The resin for dispersing the pigment in the ink is preferably an alkali-soluble resin.

  The resin (dispersant) preferably has a weight average molecular weight of 1,000 to 30,000, more preferably 3,000 to 15,000. The content (% by mass) of the resin (dispersant) in the ink is preferably 0.1% by mass or more and 10.0% by mass or less based on the total mass of the ink.

<Water-soluble organic compound>
In addition to the graft polymer described above, the first ink further includes the following general formula (C), the following general formula (D), and the group consisting of compounds represented by the following general formula (E). It is preferable to contain at least one water-soluble organic compound selected. In the following description, a water-soluble organic compound of the group consisting of compounds represented by the following general formula (C), the following general formula (D), and the following general formula (E) is referred to as “specific water-soluble”. It may be abbreviated as “organic compound”.

（一般式（Ｃ）中、Ｒ₄は置換基を有してもよい炭素数２乃至５のアルキレン基であり、Ｒ₅はそれぞれ独立に、水素原子、又は置換基を有してもよい炭素数１乃至４のアルキル基である。また、一般式（Ｄ）中、Ｒ₆は置換基を有してもよい炭素数２乃至５のアルキレン基であり、Ｒ₇は水素原子、又は置換基を有してもよい炭素数１乃至４のアルキル基である。また、一般式（Ｅ）中、ｎは１乃至３の数である。）

(In the general formula (C), R ₄ is an alkylene group having 2 to 5 carbon atoms which may have a substituent, and each R ₅ is independently a hydrogen atom or an optionally substituted carbon. And an alkyl group having a number of 1 to 4. In the general formula (D), R ₆ is an optionally substituted alkylene group having 2 to 5 carbon atoms, and R ₇ is a hydrogen atom or a substituent. (In the general formula (E), n is a number of 1 to 3.)

  Here, in addition to the above-mentioned specific graft polymer that is essential in the present invention (hereinafter simply referred to as a graft polymer), the first ink preferably further contains the specific water-soluble organic compound. The reason will be explained. The presence of the aggregate of graft polymer molecules in the ink can be confirmed, for example, by measuring the dynamic surface tension of the ink as described below. First, the dynamic surface tension of the ink containing the specific water-soluble organic compound together with the graft polymer and the ink not containing the specific water-soluble organic compound are measured for a certain lifetime. At this time, since the specific water-soluble organic compound is contained, the ink that does not form an aggregate of graft polymer molecules has a certain lifetime compared to the ink that does not contain the specific water-soluble organic compound. The value of dynamic surface tension over time decreases. This is because, in an ink in a state where the aggregate of graft polymer molecules is unwound, the graft polymer molecules are relatively oriented to the interface, and the dynamic surface tension of the ink is lowered. That is, comparing the dynamic surface tension values of these inks, if the dynamic surface tension value of the ink containing the specific water-soluble organic compound is low, the aggregate of the graft polymer molecules is contained in the ink. It can be said that it is in an unwound state. As an apparatus for measuring the dynamic surface tension, for example, Bubble Pressure Tensiometer BP2 (manufactured by KRUSS) or the like can be used.

  The compound represented by the general formula (C) and the compound represented by the general formula (D) are nitrogen-containing heterocyclic compounds, specifically, 2-pyrrolidone, N-methyl-2-pyrrolidone. 1,3-dimethyl-2-imidazolidinone, ethylene urea and the like. The compound represented by the general formula (E) is 1,2-alkanediol, specifically, 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, 1, 2-hexanediol is mentioned. In the present invention, among these compounds, it is particularly preferable to use at least one selected from 2-pyrrolidone, N-methyl-2-pyrrolidone, ethylene urea, and 1,2-hexanediol. Further, it is particularly preferable that at least one selected from 2-pyrrolidone, N-methyl-2-pyrrolidone and ethylene urea and 1,2-hexanediol are both contained in the ink.

  The total content (mass) of the compounds represented by the general formula (C), the general formula (D), and the general formula (E) with respect to the content (mass%) of the graft polymer in the first ink. %) Is preferably 2.0 times or more. That is, (total content of the specific water-soluble organic compound / content of graft polymer) = 2.0 times or more is preferable. The contents of the specific water-soluble organic compound and the graft polymer are the contents of each component in the total mass of the ink. On the other hand, when the mass ratio is less than 2.0 times, the content of the specific water-soluble organic compound is reduced in the ink, and the aggregate of the graft polymer molecules cannot be sufficiently unwound. In some cases, the effect of particularly improving the scratch resistance and glossiness cannot be obtained. The upper limit of the mass ratio is preferably 40.0 times or less, more preferably 20.0 times or less, particularly 10.0 times or less, and particularly preferably 8.0 times or less. If the upper limit of the mass ratio is larger than 40.0 times, the viscosity of the ink becomes high, so that sufficient ejection stability cannot be obtained, and therefore, an appropriate amount of ink may not be applied to the recording medium.

  The total content (% by mass) of the compounds represented by the general formula (C), the general formula (D), and the general formula (E) in the first ink is based on the total mass of the ink. 2.0% by mass or more is preferable. When the content is less than 2.0% by mass, the content of the specific water-soluble organic compound in the ink is reduced, and the aggregates of the graft polymer molecules cannot be sufficiently unwound, resulting in image scratch resistance. In some cases, the effect of particularly improving the properties and glossiness cannot be obtained. Moreover, it is preferable that the upper limit of content of the said specific water-soluble organic compound is 20.0 mass% or less. If the upper limit of the content is greater than 20.0% by mass, the viscosity of the ink increases, so that sufficient ejection stability cannot be obtained, and therefore, an appropriate amount of ink may not be applied to the recording medium. .

<Pigment>
The ink used in the present invention includes a resin dispersion type pigment (resin dispersion type pigment) in which a pigment is dispersed using a dispersant, and a self dispersion type pigment (self dispersion) in which a hydrophilic group is introduced on the surface of pigment particles. Type pigments). Also, pigments (resin-bonded self-dispersing pigments) in which organic groups containing a polymer are chemically bonded to the surface of pigment particles, microcapsules that can be dispersed without using a dispersant by increasing the dispersibility of the pigment Type pigments can also be used. Of course, these pigments having different dispersion methods may be used in combination. The pigment content (% by mass) in the ink is 0.1% by mass or more and 15.0% by mass or less, and further 1.0% by mass or more and 10.0% by mass or less, based on the total mass of the ink. Is preferred. The kind of pigment is not particularly limited, and any of inorganic pigments and organic pigments can be used.

<Aqueous medium>
In the ink used in the present invention, water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent can be used. The content (% by mass) of the water-soluble organic solvent in the ink is preferably 3.0% by mass or more and 50.0% by mass or less based on the total mass of the ink. In addition, content of this water-soluble organic solvent is content containing the specific water-soluble organic compound demonstrated above. The water-soluble organic solvent other than the specific water-soluble organic compound is not particularly limited as long as it is water-soluble, and those listed below can be used alone or in combination of two or more.

  Specifically, for example, the following water-soluble organic solvents can be used. Alkanediols such as 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol and the like. Glycol ethers such as diethylene glycol monomethyl (or ethyl) ether and triethylene glycol monoethyl (or butyl) ether. C1-C4 alkyl alcohols, such as ethanol, isopropanol, n-butanol, isobutanol, sec-butanol, and tert-butanol. Carboxylic acid amides such as N, N-dimethylformamide and N, N-dimethylacetamide. Ketones or keto alcohols such as acetone, methyl ethyl ketone, 2-methyl-2-hydroxypentan-4-one. Cyclic ethers such as tetrahydrofuran and dioxane. Glycerin. Ethylene glycols such as ethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol. Polyols such as 1,2- or 1,3-propylene glycol, 1,2- or 1,4-butylene glycol, polyethylene glycol having an average molecular weight of 200 to 1,000, thiodiglycol, 1,2,6-hexanetriol Kind. Glycols such as acetylene glycol derivatives.

  It is preferable to use deionized water (ion exchange water) as the water. The content (% by mass) of water in the ink is preferably 50.0% by mass or more and 95.0% by mass or less based on the total mass of the ink.

<Other ingredients>
In addition to the above components, the ink may contain a moisturizing solid content such as urea, a urea derivative, trimethylolpropane, and trimethylolethane. The content (% by mass) of the moisturizing solid content in the ink is 0.1% by mass or more and 20.0% by mass or less, and further 3.0% by mass or more and 10.0% by mass or less based on the total mass of the ink. It is preferable that

  Furthermore, it contains various additives such as pH adjusters, rust preventives, antiseptics, antifungal agents, antioxidants, anti-reduction agents, etc., in order to obtain inks having desired physical properties as required. Also good. In particular, when preparing the ink, it is preferable to adjust the surface tension of the second ink to be 3 mN / m or less lower than the surface tension of the first ink. Further, the water content (% by mass) based on the total ink mass in the second ink is adjusted to 90% or less with respect to the water content (% by mass) based on the total ink mass in the first ink. Is preferred.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited in any way by the following examples as long as the gist thereof is not exceeded. “Part” or “%” is based on mass unless otherwise specified.

<Synthesis of silicone graft polymer>
Graft polymers 1 to 4 were respectively synthesized according to the following procedure. In addition, although a well-known polymerization method can be used as a synthesis method, in the present Example, the graft polymers 1-4 were each synthesize | combined using the following polymerization methods. First, each monomer and azobisisobutyronitrile as a polymerization initiator were charged in a flask equipped with a stirrer, a thermometer, and a nitrogen introduction tube with the composition shown in Table 1 below. Then, 500 parts of 1-methoxy-2-propanol was used as a solvent, and a polymerization reaction was performed for 4 hours at a temperature of 110 ° C. under reflux of nitrogen gas. Next, the solution containing the obtained copolymer was dried under reduced pressure to obtain a copolymer. After adding 25 parts of methyl ethyl ketone as a solvent to the copolymer and dissolving it, 2 parts of a 30% aqueous potassium hydroxide solution was added to neutralize some of the salt-forming groups of the copolymer, and further ion-exchanged water. 300 parts were added and stirred. Thereafter, the solvent was removed under reduced pressure at a temperature of 60 ° C., and further concentrated by removing a part of water to obtain an aqueous polymer solution having a solid concentration of 20.0%. The polymers 1 to 4 thus obtained were measured for absolute molecular weight and molecular size by combining gel permeation chromatography (manufactured by Shimadzu Corporation) and a multi-angle light scattering detector (manufactured by Shoko Tsusho). As a result, the measured values of the absolute molecular weight and the molecular size were greatly different, and it was confirmed that both had a graft polymer structure. The graft polymers 1 and 2 are silicone graft polymers including a nonionic unit represented by the general formula (A) and a unit having a polysiloxane structure, and the one including these and a pigment is the first ink. . On the other hand, the graft polymers 3 and 4 do not include any of the above units, and cannot be a material for forming the first ink.

In Table 1 below, (* 1) to (* 4) represent the following monomers, respectively.
(* 1): Silaplane FM-0711 (manufactured by Chisso; monomer having polysiloxane structure represented by general formula (B ′), number average molecular weight = about 1,000)
(* 2): BHEA (product name: manufactured by Nippon Shokubai; nonionic monomer in which R ₁ and R ₂ in the general formula (A ′) are a hydrogen atom, R ₃ is an ester bond, and x is 1)
(* 3): HEMA (product name: manufactured by Nippon Shokubai; nonionic monomer in which R ₁ is a hydrogen atom, R ₂ is a methyl group, R ₃ is an ester bond, and x is 1 in the general formula (A ′))
(* 4): Blemmer PME-100 (Product name: NOF Corporation; R ₁ and R ₂ in the general formula (A ′) are methyl groups, R ₃ is an ester bond, and x is 2)

<Preparation of pigment dispersion>
(Preparation of pigment dispersion 1)
Sand mill (Kaneda) in which 10 parts of magenta pigment (CI Pigment Red 122), 6 parts of glycerin, 10 parts of resin (dispersant), and 74 parts of water were filled with zirconia beads having a diameter of 0.6 mm of 70%. And dispersed for 5 hours at 1,500 rpm. As the resin, a random copolymer having a copolymerization ratio (mass ratio) of styrene, methyl acrylate and acrylic acid of 53:29:18, a weight average molecular weight of 8,000, and an acid value of 130 mgKOH / g was used. . In addition, the said resin used previously what added the potassium hydroxide and water equivalent to said acid value, and stirred at the temperature of 80 degreeC, and was used as the aqueous solution. After dispersion, the mixture is centrifuged at 5,000 rpm for 10 minutes to remove agglomerated components, and water is used so that the pigment content is 10.0% and the resin content is 10.0%. The concentration was adjusted to obtain pigment dispersion 1.

(Preparation of pigment dispersion 2)
C. I. Instead of CI Pigment Red 122, C.I. I. Pigment dispersion 2 having a pigment content of 10.0% and a resin content of 10.0% was obtained in the same manner as in the preparation of pigment dispersion 1, except that Pigment Red 149 was used.

(Preparation of pigment dispersion 3)
C. I. Instead of CI Pigment Red 122, C.I. I. Pigment dispersion 3 having a pigment content of 10.0% and a resin content of 10.0% was obtained in the same manner as in the preparation of pigment dispersion 1, except that Pigment Yellow 74 was used.

(Preparation of pigment dispersion 4)
C. I. Instead of CI Pigment Red 122, C.I. I. Pigment dispersion 4 having a pigment content of 10.0% and a resin content of 10.0% was obtained in the same manner as in the preparation of pigment dispersion 1, except that CI Pigment Blue 15: 1 was used. .

<Preparation of ink>
Using the previously prepared graft polymers 1 to 4 and pigment dispersions 1 to 4, inks 1 to 15 were prepared using the respective components shown in the upper part of Table 2. Specifically, each component shown in the upper part of Table 2 was mixed with the composition shown in Table 2 and sufficiently stirred, and then subjected to pressure filtration with a polypropylene filter (made by Pole) having a pore size of 1.2 μm. An ink was prepared. The lower part of Table 2 shows the surface tension value of each ink and the component ratio in each ink. In addition, the measurement of surface tension was performed at room temperature (25 degreeC) using automatic surface tension meter CBVP-Z (made by Kyowa Interface Science).

<Evaluation>
(Image creation)
Each ink 1 to 15 obtained above is filled in an ink cartridge and mounted on an ink jet recording apparatus having the configuration shown in FIG. 10 to form a monochromatic image with one type of ink and two types of ink. A secondary color image was recorded using each. At that time, each ink shown in Table 4 was ejected from each position of A and B in FIG.

  Single-color image recording is performed on Super Photo Paper SP-101 (manufactured by Canon), which is a glossy recording medium, with a resolution of 1200 dpi × 1200 dpi and bi-directional printing, with the ink amount given in each printing pass being equally distributed. It was. That is, ink was ejected from the position A or B in FIG. 1, and the recording duty of each recording pass was 12.5%, so that a monochrome image having a recording duty of 100% was formed. The obtained monochromatic recorded matter was allowed to stand at room temperature for 1 day, and then evaluated by the method described later. The evaluation results are shown in Table 4.

  Secondary color images can be recorded on the same Super Photo Paper SP-101 (Canon) as described above, with a resolution of 1200 dpi × 1200 dpi, 8-pass bidirectional recording, and a combination of the two ink types shown in Table 4. Each recording method using the mask pattern shown in Table 3 was used. The recording duty of the secondary color image thus obtained was 100% of the total recording duty of each ink. The obtained secondary color recorded matter was allowed to stand at room temperature for 1 day, and then evaluated by the methods described later. The evaluation results are shown in Table 4.

(Evaluation of scratch resistance)
The image area of each monochromatic or secondary color recorded matter obtained by each of the above methods was scratched with a nail while applying a pressure strong enough to damage the non-recording portion of the recording medium. The recorded matter was visually confirmed to evaluate the scratch resistance. The evaluation criteria for scratch resistance are as follows. The results are shown in Tables 4-1 and 4-3. In the present invention, according to the following evaluation criteria, AA, A, B, and C are considered to be a sufficient level for scratch resistance, and D and E are set to an insufficient level.
AA: No nail mark was left on the surface of the image.
A: Although slight nail marks remain on the surface of the image, the coloring material was not scraped off from the recording medium.
B: Although nail marks remain on the surface of the image, the color material was not scraped off from the recording medium.
C: Nail marks remained on the surface of the image, and the color material was slightly scraped off from the recording medium.
D: The surface of the recording medium is not exposed, but the color material is clearly scraped off.
E: It is a level where there is no problem as long as the image is lightly touched, but when scratched with such a strong pressure as to scratch the non-recording portion of the recording medium, the color material was scraped off to such an extent that the surface of the recording medium could be seen.

(Glossiness evaluation)
The gloss (20 ° gloss value) in the image area of each monochromatic or secondary color recorded matter obtained above is measured using a micro haze meter (manufactured by Bic Gardner) to evaluate the gloss. It was. The evaluation criteria for glossiness are as follows. The results are shown in Tables 4-1 and 4-3.
AA: The 20 ° gloss value was 50 or more.
A: The 20 ° gloss value was 45 or more and less than 50.
B: The 20 ° gloss value was 40 or more and less than 45.
C: The 20 ° gloss value was less than 40.

(Evaluation of ink storage stability)
Each ink obtained above was put in a Teflon (registered trademark) container and stored at a temperature of 60 ° C. for one month. The particle size of the pigment in the ink before and after storage was measured with a laser zeta electrometer (trade name: ELS8000; manufactured by Otsuka Electronics Co., Ltd.), and storage stability was evaluated. The evaluation criteria for storage stability are as follows. The evaluation results are shown in Table 4-2.
A: The particle size of the pigment after storage was less than 1.1 times the particle size of the pigment before storage.
B: Pigment aggregates did not occur after storage, but the particle size of the pigment after storage was 1.1 times or more the particle size of the pigment before storage.
C: Pigment aggregates were generated in the container after storage.

(Evaluation of ink ejection characteristics: face surface condition, ejection stability)
Each ink obtained above was filled in an ink cartridge for an ink jet recording apparatus (trade name: PIXUS850i; manufactured by Canon), and set at the cyan ink position of the remodeled ink jet recording apparatus. Three images of 18 cm × 24 cm were recorded in the default mode on an office planner (manufactured by Canon) with a recording duty of 50%. At this time, the recording head surface was cleaned using a PIXUS 850i wiper blade once per recording. Thereafter, a nozzle check pattern of PIXUS850i was recorded. The state of the recording head surface at this time was visually confirmed, and the state of the face surface when each ink was ejected was evaluated. The evaluation criteria for the state of the face surface are as follows, and the results are shown in Table 4. Further, the nozzle check pattern when each ink was ejected was visually confirmed to evaluate ejection stability. The evaluation criteria of the discharge stability are as follows, and the evaluation results are shown in Table 4-2.

[Face state]
A: Almost no ink was present around the discharge port.
B: Some ink droplets existed around the discharge port.
C: A liquid film of ink was present in the form of a band around the discharge port.

(Discharge stability)
A: The nozzle check pattern was not disturbed and was recorded normally.
B: The nozzle check pattern was slightly disturbed, but there was no non-ejection.
C: The nozzle check pattern had clear non-ejection and disturbance, and recording could not be performed normally.

Claims (6)

In an inkjet recording method for performing recording on a recording medium by discharging a plurality of inks having a first ink and a second ink in an inkjet recording method,
The first ink contains at least a nonionic unit represented by the following general formula (A), a graft polymer including a unit having a polysiloxane structure, and a pigment, and The content (% by mass) of the graft polymer in the ink is 0.5 to 5.0 times the content (% by mass) of the pigment,
The second ink contains at least a pigment, and the content (mass%) of the graft polymer is 0.0 times or more and less than 0.2 times the content (mass%) of the pigment. ,
The ink jet recording method is a method in which recording is performed by repeating main scanning of a recording head n (n is an integer of 2 or more) times on a unit area of a recording medium, and the first ink is applied to the unit area. In this case, the first ink application amount V (i) during the i-th scanning satisfies the following formula [I] or formula [II].

(In the general formula (A), R ₁ and R ₂ are each independently a hydrogen atom or a methyl group, R ₃ is an ester bond or an ether bond, and x is 1 or 2, provided that R ₂ is methyl. In the case of a group, R ₃ is not an ether bond.)

The ink jet recording method is a method in which recording is performed by repeating main scanning of a recording head n (n is an integer of 2 or more) times on a unit area of a recording medium, and the first ink is applied to the unit area. The inkjet recording method according to claim 1, wherein the first ink application amount V (i) during the i-th scanning satisfies the following formula [III] or [IV].

The ink jet recording method is a method in which recording is performed by repeating main scanning of a recording head n (n is an integer of 2 or more) times on a unit area of a recording medium, and the first ink is applied to the unit area. The inkjet recording method according to claim 1, wherein the first ink application amount V (i) during the i-th scanning satisfies the following formula [V] or [VI].

  The ink jet recording method according to claim 1, wherein the surface tension of the second ink is 3 mN / m or less lower than that of the first ink.   5. The water content (% by mass) based on the total ink mass of the second ink is 90% or less with respect to the water content based on the total ink mass of the first ink. 2. The ink jet recording method according to item 1.   An ink storage unit for storing a plurality of inks and a recording head for discharging ink, and recording is performed by the ink jet recording method according to any one of claims 1 to 5. An ink jet recording apparatus configured as described above.

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