JP2006263940A - Image recording method and inkjet recording equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image recording method and inkjet recording equipment which reduce a stain or nonuniformity of a multi-order color recording part in an image printed on a plain paper medium, in particular, in a two-liquid system based on the combination of a reaction liquid with a plurality of ink. <P>SOLUTION: The recording method has a process wherein the ink in a plurality containing coloring materials in a dissolved or dispersed state and the reaction liquid containing a reactive component bringing the coloring materials in the ink into unstable states in contact with at least one kind of ink are used and wherein the ink is given to a recording medium after the reaction liquid is given to the recording medium. Herein the ink is given to the recording medium by an inkjet recording method, and on the occasion when a multi-order color image is formed with a plurality of inks including a first ink and a second ink, the ink wherein the relation between a Ka value of a droplet of the first ink and that of the droplet of the second ink is B/A>1 when the Ka value of the former is denoted by A and that of the latter by B, is used. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image recording method and an ink jet recording apparatus when printing is performed on a recording medium using a reaction liquid and a plurality of inks in combination.

  Conventionally, there is an ink jet recording method in which a liquid for improving an image is prepared separately from a normal ink for ink jet and an image is formed by adhering the liquid onto a recording medium before jetting the recording ink. Various proposals have been made. For example, a method of recording an ink containing an anionic dye after depositing a liquid having a basic polymer (see, for example, Patent Document 1), a first liquid containing a reactive chemical species, and the reactive chemistry A recording method in which a liquid containing a compound that reacts with a species is mixed on a recording medium (see, for example, Patent Document 2), and a liquid containing an organic compound having two or more cationic groups per molecule is attached. Thereafter, a method of recording an ink containing an anionic dye (for example, see Patent Document 3) has been proposed. In addition, a method of applying an ink containing an anionic dye after adhering an acidic liquid containing succinic acid or the like (see, for example, Patent Document 4), or applying a liquid for insolubilizing the dye prior to ink recording. Methods (see, for example, Patent Documents 5 and 6) have also been proposed.

  However, any of the above-described methods is intended to suppress bleeding of the image and improve the water resistance of the image by folding out the dye itself contained as a color material in the ink on the recording medium. However, the effect of suppressing bleeding between color inks of different tones is insufficient, and since the folded dye is likely to be unevenly distributed on the recording paper, the sense of uniformity in image quality may be reduced. . In particular, when plain paper is used as the recording medium, the tendency to be observed is remarkably observed because the covering property to the pulp fiber is deteriorated.

  On the other hand, in systems using pigments as ink coloring materials, an ink set using a combination of an ink containing a pigment dispersion and an ink containing a polyvalent metal has been proposed for the purpose of reducing bleeding on multicolored printed materials. In this case, for example, it is necessary to use a polyvalent metal in consideration of the compatibility with the colorant, that is, the stability of the ink, as the ink containing the polyvalent metal. There is another problem that there is a limitation and it is difficult to obtain a sufficient image density.

  As a method for solving such a problem, after applying a liquid composition containing polyvalent metal ions to a recording medium in advance, an ink having reactivity with the liquid composition is printed. Various recording methods for achieving the improvement in density have been proposed (see, for example, Patent Documents 8 to 12).

Japanese Unexamined Patent Publication No. 63-60783 Japanese Patent Laid-Open No. 63-22681 JP-A 63-299971 Japanese Unexamined Patent Publication No. 64-9279 JP-A-64-63185 JP-A 64-69381 JP-A-9-118850 JP 63-299970 A Japanese Patent Publication No. 6-86142 JP-A-9-207424 JP-A-11-349873 JP 2000-94825 A

  The present inventors have made various studies on a two-component system that uses a reaction liquid containing polyvalent metal ions and an ink that reacts when contacted with the reaction liquid as a set. As a result, a two-component system using such a set can obtain a high-quality color image having a high image density and no color bleeding. However, a new evil was recognized in the process of studying.

  That is, depending on the characteristics of the ink and the recording method, when a multi-order color image is formed using a plurality of inks, spots and unevenness (coexistence of a light portion and a dark portion) are conspicuous in the formed image. It became clear that a phenomenon that would occur. Although the cause of the phenomenon is not clear, the present inventors have assumed as follows.

  There are several possible causes for the occurrence of spots and unevenness in the formed image, but one of the causes is the aggregation of the coloring material applied to the recording medium after the second liquid during multi-color formation. This is considered to exist at various points in the recording medium.

  That is, when a reaction liquid is applied and ink is applied in a situation where a reactive component is present inside the recording medium, the color material in the first ink droplet forms an aggregate in the upper layer portion of the recording medium. On the other hand, the color material aggregate after the first ink droplet reacts with an unreacted reactive component that has not reacted with the color material in the first ink droplet to form an aggregate, or the first The unreacted reactivity enters into the inside of the recording medium by sewing the gap between the thing existing in the upper layer portion of the recording medium by adhering to the aggregate formed by the ink droplets of the ink and the aggregate formed by the first ink droplets. There are those that form aggregates on contact with the components. At that time, the color material aggregates after the first ink droplet existing in the upper layer portion of the recording medium were formed by the amount and location of the unreacted reactive component in the upper layer portion of the recording medium or the first ink droplet. Due to the difference in the size of the aggregate, the size and amount of the aggregate vary depending on the recording location. It is presumed that the fact that the size and amount of the aggregates differ depending on the recording location is one of the causes for causing spots and unevenness in the formed image. According to the study by the present inventors, the phenomenon becomes more prominent as the reactivity between the coloring material and the reactive component contained in the first ink droplet is weaker.

  Accordingly, an object of the present invention is a two-liquid system using a combination of a reaction liquid and a plurality of inks, and particularly an image recording for reducing spots and unevenness in a multi-color recording section in an image printed on a plain paper medium. A method and an inkjet recording apparatus are provided.

  The above object is achieved by the present invention described below. That is, the present invention destabilizes the dissolved state or dispersed state of the color material in the ink by contacting the plurality of inks containing the colored material in the dissolved state or dispersed state with at least one kind of ink. In a recording method using a reaction liquid containing a reactive component and applying the ink to a recording medium after applying the reaction liquid to a recording medium, the ink is applied to the recording medium by an inkjet recording method. In addition, when forming a multi-color image with a plurality of inks including at least the first ink and the second ink, the Ka value obtained by the Bristow method of the first ink droplet is A, the second ink In this image recording method, a plurality of inks having a relationship of B / A> 1 when the Ka value obtained by the Bristow method of droplets is B are used.

As a preferable form of the image recording method, the reaction solution is one having a Ka value obtained by the Bristow method of 1.3 mL · m ⁻² · msec ^−1/2 or more, and further, The coating amount is 0.5 g / m ² or more and 10 g / m ² or less with respect to the recording medium, the reaction component is a cationic reaction material, polyvalent metal ions and Examples include using a reaction liquid containing at least one selected from the salts, and using an ink containing at least a pigment as a coloring material. Examples of the polyvalent metal that is a reactive component contained in the reaction solution include Ca, Cu, Ni, Mg, Zn, Ba, Al, Fe, Cr, and Y.

  According to another aspect of the present invention, there is provided a recording head for ejecting a plurality of inks containing a color material in a dissolved state or a dispersed state, an ink cartridge having an ink containing portion containing ink, and the ink cartridge from the ink cartridge. An ink supply means for supplying ink to the recording head, and a means for supplying a reaction liquid that destabilizes the dissolved state or the dispersed state of the color material in at least one kind of ink by contacting the ink. In the ink jet recording apparatus capable of forming a multi-color image, the ink includes at least the first ink and the second ink, and the Ka value obtained by the Bristow method of the first ink droplet is A, the second ink An ink jet recording apparatus characterized in that the relationship between the Ka values when the Ka value obtained by the Bristow method for ink droplets is B is B / A> 1 It is.

As a preferred form of the ink jet recording apparatus, the reaction solution has a Ka value required by the Bristow method of 1.3 mL · m ⁻² · msec ^−1/2 or more, and further, the application amount of the reaction solution is recorded. be configured such that the 0.5 g / m ² or more 10 g / m ² or less with respect to the medium, the reactive component to be contained in the reaction liquid, it is a cationic agent, is contained in the reaction liquid reaction And the ink component contains at least one selected from polyvalent metal ions and salts thereof, and the ink contains a pigment. Examples of the polyvalent metal that is a reactive component contained in the reaction solution include Ca, Cu, Ni, Mg, Zn, Ba, Al, Fe, Cr, and Y.

  According to the present invention, a plurality of inks and a reaction liquid containing a component that destabilizes the dissolved state or dispersed state of the coloring material in the ink by contacting with at least one kind of ink are applied to the recording medium. In a two-component system having a process, it is possible to provide an image recording method and an ink jet recording apparatus capable of obtaining an image with reduced spots and unevenness in a recording portion when an image is formed with multi-order colors.

  Next, the present invention will be described in more detail with reference to preferred embodiments. In the course of studying to solve the above-described problems of the prior art, the present inventors contact a plurality of inks with at least one kind of ink to dissolve or disperse a coloring material in the ink. In the case of forming a multi-color image in a two-component system using a reaction liquid containing a component that destabilizes the liquid (hereinafter simply referred to as a reaction liquid), ink is applied to the recording medium to which the reaction liquid is applied. The present inventors have found that spots and unevenness of the multi-color recording portion can be reduced by controlling the permeability of the ink to be used to the recording medium. Specifically, when forming a multi-color image in a two-component system using a plurality of inks including at least a first ink and a second ink in which a coloring material is destabilized by a reaction liquid, When a Ka value obtained by the Bristow method for the first ink droplet is A and a Ka value obtained by the Bristow method for the second ink droplet is B, a relationship between these values is B / A> 1 It has been found effective to use ink. Here, the Ka value is a value obtained by the Bristow method as a measure representing the permeability of the ink into the recording medium. Although the reason why the above-described configuration reduces the spots and unevenness of the multi-order color recording portion is not clear, the present inventors presume as follows.

  One reason for the occurrence of spots and unevenness in the multi-color recording section is that, as described above, the size and amount of aggregates formed by the reaction liquid and the first and subsequent inks vary depending on the recording location. Conceivable. Therefore, the present inventors can reduce the spots and unevenness of the multi-color recording portion by making the color material in the first and subsequent ink droplets as large as possible in the same layer of the upper layer portion of the recording medium. We considered it possible and conducted various studies. As a result, when ink is applied to the recording medium, the low Ka value ink is used as the first ink (that is, the first droplet during recording), and the high Ka value ink is used as the second ink ( In other words, it was concluded that it is effective to use the first and subsequent inks during recording.

  That is, when a multi-color image is formed using a plurality of inks, as a result of performing the recording method using the ink as described above, the aggregates formed by the reaction liquid and the first ink droplets cause the fibers to form. It was confirmed that the gaps were reduced, and there were more color material aggregates of the second and subsequent ink droplets in the upper layer portion of the recording medium, and moreover, it was possible to reduce spots and unevenness in the multi-color recording portion. . It was also found that this phenomenon appears more prominently as the Ka value of the first ink is lower. As a result of the above studies, the present inventors have found that the first ink in the case where the ink is applied in a situation where the reactive component exists inside the recording medium in order to reduce the spots and unevenness in the multi-color recording portion. By collecting the aggregates of the coloring material contained in the droplets at a fixed position as much as possible, the gap between the fibers is reduced, and the coloring material after the first ink droplet is left as much as possible in the upper layer portion in the recording medium. I came to the conclusion that

  As one of means for reducing spots and unevenness in the multi-color recording section that can realize the above state, the Ka value of the first ink droplet is A, and the Ka value of the second ink droplet is B. It was found that the more effective the relationship of B / A> 1 holds, and the more the relationship becomes more prominent. In particular, it was found that the lower the Ka value of the first ink, the more effective, and further, the lower the reactivity between the coloring material and the reactive component in the first ink, the more remarkable the effect.

  Conversely, when forming an image with a two-component system, if the relationship between the Ka values of the above two types of ink is B / A <1, the greater the difference between the A and B values, the greater the ink. Depending on the characteristics of the recording medium and the characteristics of the recording medium, most of the aggregates of the coloring material cannot be formed in the upper layer portion of the recording medium. At the same time, it was confirmed that there was a case where it was unevenly present, resulting in spots and unevenness.

The Ka value for specifying each ink used in the present invention is a measure representing the penetrability of the ink into the recording medium, and is determined by the Bristow method described below. That is, when the ink permeability is expressed by the ink amount V per 1 m ² , the ink penetration amount V (mL / m ² = μm) after a predetermined time t has elapsed since the ink droplet was ejected. ) Is shown by the Bristow equation shown below.
V = Vr + Ka (t−tw) ^1/2

  Here, immediately after the ink droplets adhere to the surface of the recording medium, the ink is mostly absorbed in the uneven portion of the surface of the recording medium (the roughness portion of the surface of the recording medium). Almost no penetration. The time between them is the contact time (tw), and the amount of ink absorbed in the uneven portion of the recording medium at the contact time is Vr. Then, when the contact time is exceeded after the ink is deposited, the amount of penetration into the recording medium increases by the time exceeding the contact time, that is, an amount proportional to (1/2) power of (t-tw). Ka is a proportional coefficient of this increase, and indicates a value corresponding to the penetration rate. The Ka value can be measured using a liquid dynamic permeability test apparatus (for example, trade name: dynamic permeability test apparatus S; manufactured by Toyo Seiki Seisakusho Co., Ltd.) by the Bristow method.

  The Ka value according to the Bristow method in the present invention is used for plain paper [for example, a copying machine using an electrophotographic method, a page printer (laser beam printer) manufactured by Canon Inc., or a printer using an ink jet recording method. This is a value measured using a PB paper used or a PPC paper that is a copying machine paper using an electrophotographic method as a recording medium. As a measurement environment, a normal office environment, for example, a temperature of 20 to 25 ° C. and a humidity of 40 to 60% is assumed.

  Next, in the present invention, a plurality of inks containing the coloring material in a dissolved state or a dispersed state are brought into contact with at least one ink, preferably any one of the first and second inks. The reaction liquid containing a reactive component that destabilizes the dissolved state or dispersed state of the coloring material is used as a set. These constituent components will be described. The ink used in the present invention is preferably an aqueous ink in which a color material is dissolved or dispersed in an aqueous medium. First, the reaction solution in the set used in the present invention will be described.

(Reaction solution)
The reaction liquid used in the present invention is used for image recording together with ink containing a color material in a dissolved or dispersed state, and destabilizes the dissolved or dispersed state of the color material in the ink. It has a function. The instability of the dissolved state or dispersed state of the coloring material in the ink as used in the present invention means that when the ink and the reaction liquid come into contact with each other, a state such as agglomeration or gelation is caused in the mixture (hereinafter, referred to as “mixing”) It may also be expressed as “ink destabilization”). As the reactive component contained in the reaction liquid in order to destabilize the ink, it is preferable to use a cationic substance or polyvalent metal ions and salts thereof, in particular, polyvalent metal ions and salts thereof.

When the image recording method according to the present invention is carried out, the color material contained in the first ink droplet whose Ka value is adjusted as described above may form a large aggregate in the upper layer portion of the recording medium. Is possible. As a result, the gap between the fibers is reduced by the aggregate, and the ink coloring material applied after the first ink droplet is prevented from penetrating into the recording medium, thereby reducing spots and unevenness in the image. It becomes possible. In order to carry out the above phenomenon more efficiently, it is preferable that the permeation rate of the reaction liquid into the recording medium (specified by Ka value by Bristow method) is high. Specifically, 1.3 mL · m ^-2 · msec ^-1/2 It is better to be above.

Furthermore, the coating amount of the reaction solution is preferably 0.5 g / m ² or more and 10 g / m ² or less with respect to the recording medium. By setting the coating amount and the penetrating power as described above, most of the reactive components are distributed in the upper layer portion of the recording medium, and most of the color material contained in the first ink droplet is distributed in the upper layer portion of the recording medium. It becomes possible to react with a reactive component. As a result, large aggregates are formed, and it is possible to further reduce spots and unevenness in the image. As a means for distributing most of the reactive components in the upper layer portion of the recording medium, it is more efficient to lower the Ka value of the reaction liquid, but when this means is used, the characteristics and amount of ink applied, or the recording Note that depending on the characteristics of the medium, the fixing property may be deteriorated or an “overflow phenomenon” in which the liquid component oozes around the recording location may be caused.

  Examples of the method for attaching the reaction liquid to the recording medium include a coating method such as a roller coating method, a bar coating method, and a spray coating method. Further, it is also possible to use an application method in which an ink jet recording method is used in the same manner as the ink and the reaction liquid is selectively and uniformly attached only to the vicinity of the image forming area to which the ink adheres and the image forming area.

(Polyvalent metal ions and their salts)
The polyvalent metal ions and salts thereof suitable for the reactive component in the reaction solution will be described. The salt of a polyvalent metal ion is composed of a monovalent metal ion, a divalent or higher polyvalent metal ion, and an anion bonded to the polyvalent metal ion, and is soluble in water. Specific examples of the polyvalent metal ions include divalent metal ions such as Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Mg ²⁺ , Zn ²⁺ and Ba ²⁺ , Al ³⁺ , Fe ³⁺ and Cr ^{3. And} trivalent metal ions such as ⁺ and Y ³⁺ . Examples of the anion include SO ₄ ²⁻ , Cl ⁻ , CO ₃ ²⁻ , NO ₃ ⁻ , I ⁻ , Br ⁻ , ClO ₃ ⁻ , CH ₃ COO ⁻ and HCOO ⁻ . Of course, the metal salt is not limited to the above compound.

  In addition, the content of the metal salt in the reaction solution is preferably 0.01 to 20% by mass in view of the effect of the present invention. Further, the reaction solution does not necessarily have to show no absorption in the visible range. Even if absorption is shown in the visible range, absorption in the visible range may be used as long as it does not substantially affect the image.

(Aqueous medium)
Examples of the aqueous medium used in the reaction solution include water or a mixed solvent of water and a water-soluble organic solvent. Specific examples of the water-soluble organic solvent include those having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol. Alkyl alcohols; amides such as dimethylformamide and dimethylacetamide; ketones or ketoalcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol; Propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, etc. Alkylene glycols in which the alkylene group contains 2 to 6 carbon atoms; lower alkyl ether acetates such as polyethylene glycol monomethyl ether acetate; glycerin; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol Lower alkyl ethers of polyhydric alcohols such as monomethyl (or ethyl) ether; polyhydric alcohols such as trimethylolpropane and trimethylolethane; N-methyl-2-pyrrolidone and 2-pyrrolidone, 1,3-dimethyl-2- Examples include imidazolidinone. The water-soluble organic solvents as described above can be used alone or as a mixture. It is desirable to use deionized water as the water.

  Although content of the said water-soluble organic solvent contained in a reaction liquid is not specifically limited, Preferably the range of 3-50 mass% is suitable with respect to the reaction liquid total mass. The content of water contained in the reaction solution is preferably in the range of 50 to 95% by mass with respect to the total mass of the reaction solution. In addition to the above components, surfactants, antifoaming agents, antiseptics, antifungal agents, and the like can be added to obtain a reaction solution having desired physical properties as required.

[ink]
In the present invention, the reaction liquid having the above-described configuration includes a coloring material in a dissolved state or a dispersed state, and includes a plurality of first and second inks whose Ka values are adjusted as described above. Used with ink. Suitable inks for use in the present invention include inks in which a coloring material is dispersed or dissolved in an aqueous medium by ionic groups. By using such an ink and a reaction liquid in combination for recording, it is possible to obtain a preferable effect such as being able to form a high-quality image. Examples of the color material that can be used in such an ink include pigments (microencapsulated pigments, and further colored resins are also included in the category of pigments in this specification). Hereinafter, these color materials will be described in detail.

<Pigment>
Examples of the pigment that can be used include carbon black and organic pigments.
(Carbon black)
Examples of the carbon black include carbon black pigments such as furnace black, lamp black, acetylene black, and channel black. For example, Raven 7000, Ray Van 5750, Ray Van 5250, Ray Van 5000, Ray Van 3500, Ray Van 2000, and Ray Van 1500. , Ray Van 1250, Ray Van 1200, Ray Van 1190ULTRA-II, Ray Van 1170, Ray Van 1255 (manufactured by Columbia), Black Pearls L, Legal 400R, Legal 330R, Legal 660R, Mogu L Monarch 700, Monak 800, Monak 880, Monak 900, Monak 1000, Nak 1100, Monak 1300, Monak 1400, Vulcan XC-72R (above, manufactured by Cabot), Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color Black S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Printex 140V, Special Black 6, Special Black 5, Special Black 4A, Special Black 4 (made by Degussa), No. 25, no. 33, no. 40, no. 47, no. 52, no. 900, no. 2300, MCF-88, MA600, MA7, MA8, MA100 (above, manufactured by Mitsubishi Chemical Corporation) can be used, but is not limited thereto, and conventionally known carbon black can be used. is there. Further, magnetic fine particles such as magnetite and ferrite, titanium black and the like may be used as the black pigment.

(Organic pigment)
Specific examples of organic pigments include insoluble azo pigments such as Toluidine Red, Toluidine Maroon, Hansa Yellow, Benzidine Yellow, and Pyrazolone Red, soluble azo pigments such as Ritol Red, Helio Bordeaux, Pigment Scarlet, and Permanent Red 2B, Alizarin, Indantron , Derivatives from vat dyes such as thioindigo maroon, phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green, quinacridone pigments such as quinacridone red and quinacridone magenta, perylene pigments such as perylene red and perylene scarlet, isoindolinone yellow Isoindolinone pigments such as isoindolinone orange, imidazolone face such as benzimidazolone yellow, benzimidazolone orange, and benzimidazolone red Pyranthrone pigments such as pyranthrone red, pyranthrone orange, thioindigo pigments, condensed azo pigments, thioindigo pigments, flavanthrone yellow, acylamide yellow, quinophthalone yellow, nickel azo yellow, copper azomethine yellow, perinone orange, Other pigments such as anthrone orange, dianthraquinonyl red and dioxazine violet can be exemplified.

  Further, when the organic pigment is represented by a color index (CI) number, C.I. I. Pigment Yellow 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 109, 110, 117, 120, 125, 128, 137, 138, 147, 148, 151, 153, 154, 166, 168, C.I. I. Pigment orange 16, 36, 43, 51, 55, 59, 61, C.I. I. Pigment Red 9, 48, 49, 52, 53, 57, 97, 122, 123, 149, 168, 175, 176, 177, 180, 192, 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240, C.I. I. Pigment violet 19, 23, 29, 30, 37, 40, 50, C.I. I. Pigment blue 15, 15: 3, 15: 1, 15: 4, 15: 6, 22, 60, 64, C.I. I. Pigment green 7, 36, C.I. I. Examples thereof include CI Pigment Brown 23, 25, 26, and the like. Of course, conventionally known organic pigments can be used in addition to the above.

(Dispersant)
When using the above-described carbon black or organic pigment, it is preferable to use a dispersant in combination. As the dispersant, those capable of stably dispersing the above pigment in an aqueous medium by the action of an anionic group are suitably used. Specific examples of the dispersant include, for example, a styrene-acrylic acid copolymer, a styrene-acrylic acid-alkyl acrylate copolymer, a styrene-maleic acid copolymer, and a styrene-maleic acid-alkyl acrylate copolymer. Styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-maleic acid half ester copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, A styrene-maleic anhydride-maleic acid half ester copolymer or a salt thereof is included. These dispersants preferably have a weight average molecular weight in the range of 1,000 to 30,000, particularly preferably in the range of 3,000 to 15,000.

(Self-dispersing pigment)
As the coloring material, a pigment that can be dispersed in an aqueous medium without a dispersant by binding an ionic group (anionic group) to the pigment surface, a so-called self-dispersing pigment can also be used. Examples thereof include self-dispersing carbon black. Examples of the self-dispersing carbon black include those in which an anionic group is bonded to the surface of the carbon black.

(Anionic carbon black)
Examples of the anionic carbon black include at least one anion selected from —COO (M2), —SO ₃ (M2), —PO ₃ H (M2), and —PO ₃ (M2) _{2 on} the surface of the carbon black. The thing which combined the sex group is mentioned. In the above formula, M2 represents a hydrogen atom, an alkali metal, ammonium or organic ammonium. Among these, carbon black obtained by bonding —COO (M2) or —SO ₃ (M2) to the surface of carbon black to be anionic is particularly suitable for use in the present invention because of its excellent dispersibility in the ink. To get.

  Among those expressed as “M2” in the hydrophilic group, specific examples of the alkali metal include Li, Na, K, Rb and Cs. Specific examples of the organic ammonium include, for example, Examples include methylammonium, dimethylammonium, trimethylammonium, ethylammonium, diethylammonium, triethylammonium, methanolammonium, dimethanolammonium, and trimethanolammonium.

  An ink containing self-dispersing carbon black in which M2 is ammonium or organic ammonium can further improve the water resistance of a recorded image, and can be particularly preferably used in this respect. This is considered to be due to the fact that when the ink is applied onto the recording medium, ammonium is decomposed and ammonia is evaporated. Here, the self-dispersing carbon black in which M2 is ammonium includes, for example, a method of substituting M2 with ammonium using an ion exchange method for self-dispersing carbon black in which M2 is an alkali metal, Then, ammonium hydroxide is added to make M2 ammonium.

  An example of a method for producing an anionically charged self-dispersing carbon black is a method of oxidizing carbon black with sodium hypochlorite. By this method, a -COONa group is chemically bonded to the carbon black surface. Can be made.

Various hydrophilic groups as described above may be directly bonded to the surface of carbon black. Alternatively, another atomic group may be interposed between the carbon black surface and the hydrophilic group, and the hydrophilic group may be indirectly bonded to the carbon black surface. Here, specific examples of the other atomic group include, for example, a linear or branched alkylene group having 1 to 12 carbon atoms, a substituted or unsubstituted phenylene group, and a substituted or unsubstituted naphthylene group. . Here, as a substituent of a phenylene group and a naphthylene group, a C1-C6 linear or branched alkyl group is mentioned, for example. Specific examples of combinations of other atomic groups and hydrophilic groups include, for example, —C ₂ H ₄ COO (M2), —Ph—SO ₃ (M2), —Ph—COO (M2), etc. Ph represents a phenyl group).

  In the present invention, two or more of the above-described self-dispersing carbon blacks may be used as an ink coloring material appropriately selected. Further, the addition amount of the self-dispersing carbon black in the ink is preferably in the range of 0.1 to 15% by mass, particularly 1 to 10% by mass with respect to the total mass of the ink. By setting this range, the self-dispersing carbon black can maintain a sufficiently dispersed state in the ink. Further, for the purpose of adjusting the color tone of the ink, a dye may be added as a coloring material in addition to the self-dispersing carbon black.

(Colored fine particles / microencapsulated pigment)
In addition to the color materials described above, pigments microencapsulated with a polymer or the like, and colored fine particles in which the periphery of resin particles is coated with a color material can also be used. The microcapsules are inherently dispersible in an aqueous medium, but a dispersant as described above may be further coexisted in the ink in order to enhance the dispersion stability. Moreover, when using colored fine particles as a coloring material, it is preferable to use the anionic dispersant described above.

<Aqueous medium>
The aqueous medium in which the coloring material as described above is dispersed is not particularly limited, and the same aqueous medium as described above can be used for the reaction liquid. In addition, when the color ink is adhered to a recording medium by an ink jet method (for example, bubble jet (registered trademark) method), the ink has a desired viscosity and surface tension so as to have excellent ink jet discharge characteristics as described above. It is preferable to prepare so that it has.

  Examples of the aqueous medium used in the ink used in the present invention include water or a mixed solvent of water and a water-soluble organic solvent. As the water-soluble organic solvent, those having an effect of preventing the reaction solution from drying are particularly preferable. As specific water-soluble organic solvents, any of the various water-soluble organic solvents mentioned above as those used in the reaction solution can be used. The water-soluble organic solvent can be used alone or as a mixture. It is desirable to use deionized water as the water.

  The content of the water-soluble organic solvent contained in the ink used in the present invention is not particularly limited, but is preferably in the range of 3 to 50% by mass with respect to the total mass of the ink. The content of water contained in the ink is preferably in the range of 50 to 95% by mass with respect to the total mass of the reaction solution. In addition to the above components, a moisturizing agent may be added as necessary, and surfactants, antifoaming agents, antiseptics, antifungal agents, etc. may be added to obtain a reaction liquid having desired physical properties. It doesn't matter.

(set)
In the present invention, it is assumed that a plurality of inks configured as described above and a reaction liquid are used together as a set, but the color tone of the ink constituting the set is not particularly limited. , Magenta, cyan, red, green, blue and black may be used as the ink showing at least one color tone. Specifically, it can be used by appropriately selecting from the above-described color materials so as to obtain ink having a desired color tone. Here, the content of the color material in each ink depends on the color material to be used, but may be appropriately selected so that the ink has excellent ink jet ejection characteristics and has a desired color tone and density. As a standard, for example, the range is 1 to 50% by mass with respect to the total mass of the ink. In the present invention, the ink combined with the reaction liquid is an ink set suitable for forming a multicolor image by combining two or more inks having different color tones. In this case, at least one of the two or more inks is used. However, it is preferable that the first and second inks each having the Ka value adjusted as described above react with the reaction liquid.

  Examples of the ink that reacts with the reaction liquid include an ink in which a coloring material is dispersed in an aqueous medium by the action of an ionic group. The ink other than the above may be an ink containing a dye as a coloring material. Of course, all the inks used may be inks in which the coloring material is dispersed in an aqueous medium by the action of ionic groups. According to such a set, it is possible to suppress bleeding when inks of different color tones are applied adjacently on a recording medium, which is a problem when a multicolor image is formed by an ink jet apparatus. Bleeding, which is a problem in inkjet multicolor images, tends to be particularly noticeable between black ink and other color inks. Therefore, the coloring material is applied to the aqueous medium by the action of ionic groups so as to interact with the reaction liquid. A black ink having a dispersed structure may be combined.

[Recording method and apparatus]
The reaction liquid used in the present invention is used for image formation together with a plurality of inks having a combination of specific Ka values that are destabilized by reactive components contained in the reaction liquid. As long as it is a recording method, at least recording with ink is performed by an inkjet recording method. More specifically, an image forming method including a step of applying a reaction liquid to at least a region of the recording medium to which ink is applied, and a step of applying ink to the recording medium by an ink jet method. As a result, the ink is aggregated or gelled on the recording medium by the reaction liquid, and in particular, no color bleeding occurs, and further, the color material does not show through on the back side of the print. A quality image can be obtained stably. In particular, in the present invention, since a plurality of inks including at least two types of inks having a specific combination of Ka values are used, when a multi-order color image is formed, an image with reduced spots and unevenness in the recording portion. Can be obtained. In addition, the reaction solution used in the present invention is prevented from changing over time, and even when stored, there is no significant change in the reactivity of the reaction solution with the ink. Since there is no problem and excellent storage stability, a high-quality image can be stably obtained.

  Examples of the method for applying the reaction liquid to the recording medium in the present invention include a method using an ink jet recording system in the same manner as the ink, a method for applying the reaction liquid to the recording medium with a roller, and the like. In these, the application | coating with a roller etc. which does not need to consider discharge property etc. is preferable.

The amount of the reaction liquid applied to the recording medium can be appropriately adjusted according to the polyvalent metal ion species in the reaction liquid, the amount thereof, or the ink to be reacted therewith, but is 0.5 g / m ² or more and 10 g / m ² or less. It is preferable from the viewpoints of solid uniformity and fixability of the image of the obtained recorded matter. More preferably, it is more than ² g / m ² and 5 g / m ² or less.

(Inkjet recording device)
FIG. 1 shows an example of an ink jet recording apparatus.
This image forming apparatus adopts a serial type ink jet recording method, and applies a reaction liquid to a recording head 1, a sheet feeding tray 17 for feeding a recording medium (hereinafter also referred to as recording sheet) 19, and a reaction liquid. A sheet feeding cassette 16 integrally formed with the unit for driving, a driving unit for reciprocating the recording head in a direction orthogonal to the conveyance direction of the recording sheet, and a control unit for controlling the driving of these components. Have.

  The recording head 1 is mounted on the carriage 2 so that the surface on which the ink discharge ports are formed is oriented toward the platen 11. Although not shown, the recording head 1 includes the ink discharge port, a plurality of electric heating element elements (for example, heating resistance elements) for heating the ink liquid, and a substrate for supporting the same. The recording head 1 has an ink cartridge mounted in the carriage on the top thereof.

  The carriage 2 carries the recording head 1 and can reciprocate along two guide shafts 9 extending in parallel along the width direction of the recording paper 19. The recording head 1 is driven in synchronism with the reciprocating movement of the carriage and ejects ink droplets onto the recording paper 19 to form an image.

  The paper feed cassette 16 can be detached from the image forming apparatus main body. The recording paper 19 is stacked and stored on a paper feed tray 17 in the paper feed cassette 16. At the time of paper feeding, the uppermost sheet is pressed against the paper feed roller 10 by a spring 18 that presses the paper feed tray 17 upward. The sheet feeding roller 10 is a roller having a substantially half moon shape in cross section. The sheet feeding roller 10 is driven and rotated by a motor (not shown) and feeds only the uppermost sheet (recording paper 19) by a separation claw (not shown).

  The separated recording paper 19 is fed along the conveyance surface 16A of the paper feed cassette 16 and the conveyance surface 27A of the paper guide 27 by the large-diameter intermediate roller 12 and the small-diameter application roller 6 in pressure contact therewith. Are transported. These transport surfaces are formed by curved surfaces that draw a concentric arc concentric with the intermediate roller 12. Therefore, the recording paper 19 reverses its transport direction by passing through these transport surfaces 16A and 27A. That is, the surface on which the recording paper 19 is printed is directed downward until it is conveyed from the paper feed tray 17 and reaches the intermediate roller 12, but when facing the recording head 1, it is directed upward (recording). Turn to the head side. Therefore, the printing surface of the recording paper always faces the outside of the image forming apparatus.

  The reaction liquid application means is provided in the paper feed cassette 16 and is a replenishment tank 22 for supplying the reaction liquid 15 and an intermediate part rotatably supported with a part of the peripheral surface immersed in the tank 22. The roller 12 and the application roller 6 are arranged so as to be parallel to the intermediate roller and are in contact with the intermediate roller 12 and rotate in the same direction. The application roller 6 is arranged so that the intermediate roller 12 for conveying the recording paper 19 is in contact with and parallel to the peripheral surface. Therefore, when the recording paper 19 is transported, the intermediate roller 12 and the application roller 6 rotate with the rotation of the intermediate roller 12. As a result, the reaction liquid 15 is supplied to the peripheral surface of the application roller 6 by the supply roller 13, and the reaction liquid is evenly applied to the printing surface of the recording paper 19 sandwiched between the application roller 6 and the intermediate roller 12 by the supply roller 6. Is done.

  In the image forming apparatus, the float 14 is provided in the replenishing tank 22. The float 14 is a substance having a specific gravity lighter than that of the reaction solution 15 and floats on the surface of the reaction solution 15 so that the remaining amount of the reaction solution can be visually confirmed from the outside through the remaining amount display window 21 which is a transparent member.

  FIG. 2 is a front view of the remaining amount display portion. The remaining amount display portion is provided with a display indicating the level of the remaining amount along the longitudinal direction of the remaining amount display window 21. In the figure, the state where the surface of the reaction solution or the float 14 has reached the position indicated as “Full” is full. On the other hand, when the liquid level of the reaction solution or the float 14 is present at the position labeled “Add”, it indicates that the reaction solution is low. Therefore, it can be seen at a glance that the reaction solution 15 should be replenished when the reaction solution 15 is gradually reduced and the float 14 is lowered to the Add line.

  As a method for replenishing the reaction solution, as shown in FIG. 3, the tip of the injection device 23 is inserted into the injection port 20 made of a cut rubber member with the paper feed cassette 16 pulled out from the image forming apparatus main body. By inserting, the reaction liquid is injected into the replenishing tank 22.

  In this way, the recording paper coated with the reaction liquid is then fed by a predetermined amount by the main transport roller 7 and the pinch roller 8 in pressure contact therewith and transported to the recording unit, and ink is applied from the recording head 1. The The recording sheet 19 fed and printed in the above configuration is discharged and conveyed by the discharge roller 3 and the spur 4 in pressure contact with the discharge roller 3 and stacked on the discharge tray 5.

  In addition, when the reaction liquid is applied by a roller or the like, the ink can be effectively destabilized with a small application amount and the recorded matter can be effectively made especially when the viscosity of the reaction liquid is higher than the viscosity of the ink. It is preferable because of its good fixability. More specifically, when the viscosity of the reaction liquid is higher, the polyvalent metal ions are more likely to stay above the recording medium, and thus more easily react with the ink.

  On the other hand, after the ink reacts with the reaction liquid, the colorant component in the ink stays above the recording medium, and the solvent, water, etc. quickly penetrate into the recording medium, that is, the solid-liquid separation can be performed quickly. Therefore, a lower viscosity is preferable from the viewpoint of the fixability of the recorded matter. The viscosity of the reaction liquid when the reaction liquid is applied by a roller or the like is preferably 3 mPa · s to 100 mPa · s, and more preferably 5 mPa · s to 60 mPa · s. The viscosity of the reaction liquid and ink in the present invention can be measured by a conventional method under an environment of 25 ° C.

On the other hand, in the image recording method according to the present invention, when applying each ink and reaction liquid onto the recording medium, the order of applying the ink onto the recording medium may be various recording methods such as the following methods. Any of them may be selected as appropriate.
a): Ink is printed after the reaction liquid is printed.
b): Printing the reaction liquid after printing the ink.
c): After printing the ink, the reaction liquid is printed, and further the ink is printed.
d): After printing the reaction liquid, the ink is printed and the reaction liquid is further printed.
In view of the object of the present invention, a) or d) including at least a step of recording the reaction liquid on a recording medium prior to the ink is preferable.

  FIG. 4 shows another example of the ink jet recording apparatus. In FIG. 4, reference numeral 61 denotes a blade as a wiping member, one end of which is held and fixed by a blade holding member, and forms a cantilever. The blade 61 is disposed at a position adjacent to the recording area by the recording head 65, and in this example, is held in a form protruding in the moving path of the recording head 65.

  Reference numeral 62 denotes a cap on the projection port surface of the recording head 65, which is disposed at a home position adjacent to the blade 61, moves in a direction perpendicular to the moving direction of the recording head 65, contacts the ink ejection port surface, and performs capping. The structure to perform is provided. Further, reference numeral 63 denotes an ink absorber provided adjacent to the blade 61 and, like the blade 61, is held in a form protruding in the moving path of the recording head 65. The blade 61, the cap 62, and the ink absorber 63 constitute an ejection recovery unit 64, and the blade 61 and the ink absorber 63 remove moisture, dust, and the like from the ejection port surface. Further, each ink of the recording head, and further, ink positioned at the discharge port of the reaction liquid is sucked by a pump (not shown) through a cap, and the original ink of the recording head, or the ink and the reaction liquid This constitutes a recovery unit that restores the original discharge performance.

  Reference numeral 65 denotes a recording head which has discharge energy generating means and performs recording by discharging ink onto a recording medium facing the discharge port surface where the discharge port is arranged. Reference numeral 66 denotes a movement of the recording head 65 by mounting the recording head 65. It is a carriage for performing. The carriage 66 is slidably engaged with the guide shaft 67, and a part of the carriage 66 is connected to a belt 69 (not shown) driven by a motor 68. As a result, the carriage 66 can move along the guide shaft 67, and the recording area and its adjacent area can be moved by the recording head 65. 51 is a paper feed section for inserting a recording medium, and 52 is a paper feed roller driven by a motor (not shown).

  With these configurations, the recording medium is fed to a position facing the 65 discharge port surface of the recording head, and is discharged to a paper discharge portion provided with a paper discharge roller 53 as recording progresses. In the above configuration, when the recording head 65 finishes recording and returns to the home position, the cap 62 of the ejection recovery unit 64 is retracted from the moving path of the recording head 65, but the blade 61 protrudes into the moving path. As a result, the ejection port of the recording head 65 is wiped. When the cap 62 is in contact with the ejection surface of the recording head 65 to perform capping, the cap 62 moves so as to protrude into the moving path of the recording head. When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are at the same position as that at the time of wiping described above. As a result, the ejection port surface of the recording head 65 is wiped even during this movement.

  The above-mentioned movement of the recording head to the home position is not only at the end of recording or at the time of ejection recovery, but also to the home position adjacent to the recording area at a predetermined interval while the recording head moves the recording area for recording. Then, the wiping is performed with this movement.

(Ink characteristics; inkjet ejection characteristics, permeability to recording media)
As the ink jet recording method used in the present invention, there is a recording method in which mechanical energy is applied to ink to eject droplets, and a recording method in which thermal energy is applied to ink and ink droplets are ejected by foaming of the ink, In these recording methods, not only the ink used in the present invention but also a reaction liquid can be used. In that case, it is preferable that the reaction liquid and the ink having the above-described configuration according to the present invention have characteristics that can be ejected from an inkjet head. From the viewpoint of dischargeability from an inkjet head, the characteristics of these liquids are, for example, a viscosity of 1 to 15 mPa · s, a surface tension of 25 mN / m (dyne / cm) or more, particularly a viscosity of 1 to 5 mPa. -It is preferable that s and surface tension shall be 25-50 mN / m (dyne / cm). Furthermore, since the reaction liquid used in the present invention needs to react only with a specific ink on a recording medium such as paper, the reaction liquid does not bleed into a portion other than the recording portion with the specific ink. It is preferable that the surface tension of the reaction liquid is larger than that of the ink to be destabilized by the reaction liquid within a range that can be discharged from the ink jet head.

(ink cartridge)
FIG. 5 is a diagram showing an example of a cartridge 45 that contains a member that supplies ink or reaction liquid to the recording head, for example, ink or reaction liquid supplied via a tube. Here, reference numeral 40 denotes a storage portion, for example, a bag, which stores ink for supply or reaction liquid, and a rubber stopper 42 is provided at the tip thereof. By inserting a needle (not shown) into the stopper 42, the ink or reaction liquid in the bag 40 can be supplied to the head. Reference numeral 44 denotes an absorber that receives waste ink or waste reaction liquid. The container 40 preferably has a liquid contact surface with an ink or a reaction liquid formed of polyolefin, particularly polyethylene. For example, as shown in FIG. 6, such a cartridge is configured to be detachable from a recording head 901 that discharges ink or a reaction liquid. In addition, when the cartridge 45 is mounted on the recording head, the ink or reaction is performed. The liquid is supplied to the recording head 901.

  Hereinafter, although it demonstrates more concretely using an Example and a comparative example, this invention is not limited by the following Example, unless the summary is exceeded. In the following description, “parts” and “%” are based on mass unless otherwise specified. First, reaction liquids and inks for each color used in Examples and Comparative Examples were prepared.

[Preparation of reaction solution]
(Reaction solution)
・ Calcium nitrate (tetrahydrate) 8 parts ・ Trimethylolpropane 6 parts ・ Glycerin 5 parts ・ Diethylene glycol 5 parts ・ Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 1 part ・ Water 75 parts

[Preparation of ink]
<Preparation of cyan ink>
C. a pigment. I. 10 parts of Pigment Blue 15: 3 [Product name: Fastgen Blue FGF, manufactured by Dainippon Ink & Chemicals, Inc.], anionic polymer P-1 (styrene-acrylic acid copolymer, acid value 200, weight average) An aqueous solution having a molecular weight of 10,000 and a solid content of 10%, 20 parts of a neutralizing agent: potassium hydroxide) and 70 parts of pure water were mixed, and these were charged into a batch type vertical sand mill (manufactured by IMEX). 150 parts of zirconia beads were filled and dispersed for 5 hours while cooling with water. After this dispersion was centrifuged to remove coarse particles, Pigment Dispersion C having a final preparation with a solid content of about 12% and a weight average particle size of 100 nm was obtained. Using the resulting pigment dispersion C, cyan inks 1 and 2 having the following composition were prepared.

(Composition of cyan ink 1)
-Pigment dispersion C 30 parts-Glycerol 9 parts-Diethylene glycol 6 parts-Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 1 part-Water 54 parts

(Composition of cyan ink 2)
-Pigment dispersion C 30 parts-Glycerol 9 parts-Diethylene glycol 6 parts-Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 0.1 part-Water 54.9 parts

<Preparation of magenta ink>
C. a pigment. I. Pigment Red 122 (Dainippon Ink Chemical Co., Ltd.) 10 parts, anionic polymer P-1 (styrene-acrylic acid copolymer, acid value 200, weight average molecular weight 10,000, solid content 10% aqueous solution 20 parts of neutralizing agent: potassium hydroxide) and 70 parts of pure water are mixed, these materials are charged into a batch type vertical sand mill (manufactured by IMEX), and 150 parts of 0.3 mm diameter zirconia beads are filled. Dispersion treatment was performed for 5 hours while cooling with water. After this dispersion was centrifuged to remove coarse particles, a pigment dispersion M having a final preparation with a solid content of about 12% and a weight average particle size of 150 nm was obtained. Using the obtained pigment dispersion M, magenta inks 1 and 2 having the following composition were prepared.

(Composition of magenta ink 1)
-Pigment dispersion M 30 parts-Glycerol 9 parts-Diethylene glycol 6 parts-Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 1 part-Water 54 parts

(Composition of magenta ink 2)
-Pigment dispersion M 30 parts-Glycerol 9 parts-Diethylene glycol 6 parts-Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 0.3 parts-Water 54.7 parts

<Preparation of yellow ink>
C. a pigment. I. Pigment Yellow 180 (product name: Nova Palm Yellow PH-G, manufactured by Hoechst), anionic polymer P-1 (styrene-acrylic acid copolymer, acid value 200, weight average molecular weight 10,000, solid 20 parts of 10% aqueous solution, neutralizer: potassium hydroxide) and 70 parts of pure water are mixed, and these materials are charged into a batch type vertical sand mill (manufactured by IMEX), and 0.3 mm diameter zirconia beads are prepared. 150 parts were filled and dispersed for 5 hours while cooling with water. After this dispersion was centrifuged to remove coarse particles, Pigment Dispersion Y having a final preparation with a solid content of about 12% and a weight average particle size of 125 nm was obtained. Using the obtained pigment dispersion Y, yellow inks 1 and 2 having the following composition were prepared.

(Composition of yellow ink 1)
-Pigment dispersion Y 30 parts-Glycerol 9 parts-Diethylene glycol 6 parts-Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 1 part-Water 54 parts

(Composition of yellow ink 2)
-Pigment dispersion Y 30 parts-Glycerol 9 parts-Diethylene glycol 6 parts-Acetylene glycol ethylene oxide adduct (trade name: acetylenol EH) 0.1 part-Water 54.9 parts

<Characteristics of each ink>
Table 1 shows the Ka value of each ink and reaction solution. For the Ka value, a liquid dynamic permeability test apparatus S (manufactured by Toyo Seiki Seisakusho) using the Bristow method was used. Also, PB paper (manufactured by Canon) was used as the recording medium when measuring the Ka value.

<Example 1>
The previously prepared reaction liquid, yellow ink 2 and magenta ink 1 were combined to make set 1. In the set, the reaction solution was applied onto the recording medium with a coating roller. Thereafter, a modification of an ink jet recording apparatus BJF-900 (manufactured by Canon) having an on-demand type multi-recording head that discharges ink by applying thermal energy according to a recording signal mounted with yellow ink 2 and magenta ink 1 to the ink. An evaluation image was printed using a machine. The resulting secondary color image was evaluated for spots and unevenness by the method described later. During the printing, yellow ink 2 is mounted at the M position, magenta ink 1 is mounted at the Y position, and the ink is applied to the recording medium in the order of yellow ink 2 (Ka value = 0.36) and magenta ink 1 (Ka value = 4). Printed as given. As the recording medium, commercially available copy paper, bond paper, recycled paper, or other plain paper was used. Further, the speed of the roller and the contact pressure of the roller to the recording medium were adjusted so that the coating amount of the reaction solution was 2.4 g / m ² . The evaluation results are shown in Table 2 below.

<Example 2>
The previously prepared reaction liquid, yellow ink 2 and cyan ink 1 were combined to form set 2. In the set, the reaction solution was applied onto the recording medium with a coating roller. Thereafter, a modification of the ink jet recording apparatus BJF-900 (manufactured by Canon) having an on-demand type multi-recording head that ejects ink by applying thermal energy corresponding to a recording signal loaded with yellow ink 2 and cyan ink 1 to the ink. An evaluation image was printed using a machine. The resulting secondary color image was evaluated for spots and unevenness by the method described later. During the printing, yellow ink 2 is mounted at the M position, cyan ink 1 is mounted at the Y position, and ink is recorded in the order of yellow ink 2 (Ka value = 0.36) and cyan ink 1 (Ka value = 4.2). Printed as applied to the media. As the recording medium, commercially available copy paper, bond paper, recycled paper, or other plain paper was used. Further, the speed of the roller and the contact pressure of the roller to the recording medium were adjusted so that the coating amount of the reaction solution was 2.4 g / m ² . The evaluation results are shown in Table 2 below.

<Example 3>
The previously prepared reaction solution, magenta ink 2 and cyan ink 1 were combined to form set 3. In the set, the reaction solution was applied onto the recording medium with a coating roller. Thereafter, a modification of the ink jet recording apparatus BJF-900 (manufactured by Canon Inc.) having an on-demand type multi-recording head that ejects ink by applying thermal energy corresponding to a recording signal loaded with magenta ink 2 and cyan ink 1 to the ink. An evaluation image was printed using a machine. The resulting secondary color image was evaluated for spots and unevenness by the method described later. During the above printing, magenta ink 2 is mounted at the M position, cyan ink 1 is mounted at the Y position, and ink is recorded in the order of magenta ink 2 (Ka value = 0.92) and cyan ink 1 (Ka value = 4.2). Printed as applied to the media. As the recording medium, commercially available copy paper, bond paper, recycled paper, or other plain paper was used. Further, the speed of the roller and the contact pressure of the roller to the recording medium were adjusted so that the coating amount of the reaction solution was 2.4 g / m ² . The evaluation results are shown in Table 2 below.

<Example 4>
The previously prepared reaction liquid, yellow ink 2, magenta ink 2 and cyan ink 1 were combined into a set 4. In the set, the reaction solution was applied onto the recording medium with a coating roller. Thereafter, an inkjet recording apparatus BJF-900 (Canon) having an on-demand type multi-recording head that discharges ink by applying thermal energy according to a recording signal mounted with yellow ink 2, magenta ink 2 and cyan sink 1 to the ink. Evaluation images were printed using a modified machine. The resulting multi-order color image was evaluated for spots and unevenness by the method described later. During the above printing, yellow ink 2 is mounted at the C position, magenta ink 2 is mounted at the M position, and cyan ink 1 is mounted at the Y position, and the yellow ink 2 (Ka value = 0.36) and the magenta ink 2 (Ka value = 0.0). 92) and cyan ink 1 (Ka value = 4.2) were printed in such a manner that the ink was applied to the recording medium. As the recording medium, commercially available copy paper, bond paper, recycled paper, or other plain paper was used. Further, the speed of the roller and the contact pressure of the roller to the recording medium were adjusted so that the coating amount of the reaction solution was 2.4 g / m ² . The evaluation results are shown in Table 2 below.

<Comparative Example 1>
The previously prepared reaction liquid, yellow ink 1 and magenta ink 2 were combined to form set 5. In the set, the reaction solution was applied onto the recording medium with a coating roller. Thereafter, a modification of an ink jet recording apparatus BJF-900 (manufactured by Canon) having an on-demand type multi-recording head that discharges ink by applying thermal energy corresponding to a recording signal mounted with yellow ink 1 and magenta ink 2 to the ink. An evaluation image was printed using a machine. The resulting secondary color image was evaluated for spots and unevenness by the method described later. During the printing, yellow ink 1 is mounted at the M position and magenta ink 2 is mounted at the Y position, and ink is recorded in the order of yellow ink 1 (Ka value = 4.2) and magenta ink 2 (Ka value = 0.92). Printed as applied to the media. As the recording medium, commercially available copy paper, bond paper, recycled paper, or other plain paper was used. Further, the speed of the roller and the contact pressure of the roller to the recording medium were adjusted so that the coating amount of the reaction solution was 2.4 g / m ² . The evaluation results are shown in Table 2 below.

<Comparative example 2>
The previously prepared reaction solution, yellow ink 1 and cyan ink 2 were combined to form set 6. In the set, the reaction solution was applied onto the recording medium with a coating roller. Thereafter, a modification of an ink jet recording apparatus BJF-900 (manufactured by Canon) having an on-demand type multi-recording head that discharges ink by applying thermal energy corresponding to a recording signal mounted with yellow ink 1 and cyan ink 2 to the ink. An evaluation image was printed using a machine. The resulting secondary color image was evaluated for spots and unevenness by the method described later. During the printing, yellow ink 1 is mounted at the M position and cyan ink 2 is mounted at the Y position, and ink is recorded in the order of yellow ink 1 (Ka value = 4.2) and cyan ink 2 (Ka value = 0.36). Printed as applied to the media. As the recording medium, commercially available copy paper, bond paper, recycled paper, or other plain paper was used. Further, the speed of the roller and the contact pressure of the roller to the recording medium were adjusted so that the coating amount of the reaction solution was 2.4 g / m ² . The evaluation results are shown in Table 2 below.

<Comparative Example 3>
The reaction liquid prepared previously, magenta ink 1 and cyan ink 2 were combined into a set 7. In the set, the reaction solution was applied onto the recording medium with a coating roller. Thereafter, a modification of the ink jet recording apparatus BJF-900 (manufactured by Canon) having an on-demand type multi-recording head that discharges ink by applying thermal energy corresponding to a recording signal loaded with magenta ink 1 and cyan ink 2 to the ink. An evaluation image was printed using a machine. The resulting secondary color image was evaluated for spots and unevenness by the method described later. At the time of the above printing, magenta ink 1 is mounted at the M position and cyan ink 2 is mounted at the Y position, and the magenta ink 1 (Ka value = 4) and cyan ink 2 (Ka value = 0.36) are sequentially applied to the recording medium. Printed as given. As the recording medium, commercially available copy paper, bond paper, recycled paper, or other plain paper was used. Further, the speed of the roller and the contact pressure of the roller to the recording medium were adjusted so that the coating amount of the reaction solution was 2.4 g / m ² . The evaluation results are shown in Table 2 below.

<Comparative example 4>
The previously prepared reaction liquid, yellow ink 1, magenta ink 2 and cyan ink 2 were combined to form set 8. In the set, the reaction solution was applied onto the recording medium with a coating roller. Thereafter, an inkjet recording apparatus BJF-900 (Canon) having an on-demand type multi-recording head that discharges ink by applying thermal energy corresponding to a recording signal mounted with yellow ink 1, magenta ink 2 and cyan sink 2 to the ink. Evaluation images were printed using a modified machine. The resulting multi-order color image was evaluated for spots and unevenness by the method described later. During the printing, yellow ink 1 is mounted at the C position, magenta ink 2 is mounted at the M position, and cyan ink 2 is mounted at the Y position. The yellow ink 1 (Ka value = 4.2) and the magenta ink 2 (Ka value = 0.0). 92) and cyan ink 2 (Ka value = 0.36) were printed in this order so that the ink was applied to the recording medium. As the recording medium, commercially available copy paper, bond paper, recycled paper, or other plain paper was used. Further, the speed of the roller and the contact pressure of the roller to the recording medium were adjusted so that the coating amount of the reaction solution was 2.4 g / m ² . The evaluation results are shown in Table 2 below.

[Evaluation of spots and unevenness in multi-order color images]
In the above printing, a secondary color solid image having a square of 2 cm × 2 cm was formed. The evaluation was performed by visually observing each obtained printed matter at a distance of about 30 cm from the printed matter, and compared according to the following criteria. The obtained results are shown in Table 2. Table 2 also shows the relationship of B / A when the Ka value of the first drop of ink is A and the Ka value of the second drop of ink is B.
a: Unevenness is not seen in the obtained printed matter.
b: Unevenness is observed in the obtained printed matter.

  As shown in the above results, when multi-color formation is performed in a two-liquid system using a combination of a reaction liquid and a plurality of inks, the Ka value (A) of the ink first applied to the recording medium is It was confirmed that the spots and unevenness of the multi-order color recording portion were effectively reduced by printing so that the Ka value (B) of the dripping ink was lower.

1 is a schematic sectional side view showing an example of an ink jet recording apparatus according to the present invention. FIG. 2 is a front sectional view of a reaction liquid remaining amount display portion provided in the ink jet recording apparatus of FIG. 1. FIG. 2 is a schematic cross-sectional side view showing a state where a reaction liquid is replenished in the ink jet recording apparatus of FIG. 1. 1 is a schematic perspective view illustrating an example of an ink jet recording apparatus according to the present invention. It is a longitudinal cross-sectional view which shows an example of an ink cartridge. FIG. 2 is a schematic plan view showing a state where an ink cartridge constituting the ink jet recording apparatus according to the present invention is mounted on a recording head.

Explanation of symbols

1: Recording head 2: Carriage 3: Paper discharge roller 6: Application roller 7: Main transport roller 8: Pinch roller 10: Paper feed roller 11: Platen 12: Intermediate roller 13: Supply roller 14: Float 15: Reaction liquid 16: Paper cassette 19: Recording medium (recording paper)
20: injection port 21: remaining amount display window 22: replenishment tank 23: injection device 27: paper guide 27A: paper guide transport surface 40: bag 42: stopper 44: absorber 45: cartridge 51: paper feed unit 52: paper Feed roller 53: Paper discharge roller 61: Blade 62: Cap 63: Ink absorber 64: Discharge recovery unit 65, 901: Recording head 66: Carriage 67: Guide shaft 68: Motor 69: Belt

Claims (14)

  A plurality of inks containing a color material in a dissolved state or a dispersed state and a reactive component that destabilizes the dissolved state or dispersed state of the color material in the ink by contacting with at least one kind of ink In a recording method comprising a step of applying a reaction liquid to a recording medium after applying the reaction liquid to a recording medium, the ink is applied to the recording medium by an inkjet recording method, and at least a first When forming a multi-color image with a plurality of inks including the first ink and the second ink, the Ka value obtained by the Bristow method for the first ink droplet is obtained by A, and the Bristow method for the second ink droplet is obtained. An image recording method using a plurality of inks having a relationship of B / A> 1 when a Ka value obtained is B. The image recording method according to claim 1, wherein the reaction solution uses a Ka value obtained by the Bristow method of 1.3 mL · m ⁻² · msec ^−1/2 or more. 3. The image recording method according to claim 1, wherein the coating amount of the reaction liquid is 0.5 g / m ² or more and 10 g / m ² or less with respect to the recording medium.   The image recording method according to claim 1, wherein a reaction liquid in which the reactive component is a cationic substance is used.   The image recording method according to claim 1, wherein the reactive component includes a reaction liquid containing at least one selected from ions of polyvalent metals and salts thereof.   6. The image recording method according to claim 5, wherein the polyvalent metal is at least one selected from Ca, Cu, Ni, Mg, Zn, Ba, Al, Fe, Cr and Y.   The image recording method according to claim 1, wherein an ink containing at least a pigment is used as the color material.   A recording head for discharging a plurality of inks containing a coloring material in a dissolved state or a dispersed state, an ink cartridge having an ink containing portion containing ink, and an ink for supplying ink from the ink cartridge to the recording head An ink jet capable of forming a multi-order color image, comprising: a supply means and a means for supplying a reaction liquid that destabilizes a dissolved state or a dispersed state of a coloring material in at least one kind of ink by contacting the ink. In the recording apparatus, the ink includes at least the first ink and the second ink, and the Ka value obtained by the Bristow method of the first ink droplet is A, and the Ka value obtained by the Bristow method of the second ink droplet is obtained. An ink jet recording apparatus, wherein the relationship of Ka values when the value is B is B / A> 1. The ink jet recording apparatus according to claim 8, wherein the reaction solution has a Ka value obtained by the Bristow method of 1.3 mL · m ⁻² · msec ^−1/2 or more. Further, the coating amount of the reaction solution, the ink jet recording apparatus according to claim 8 or 9 is configured so as to be 0.5 g / m ² or more 10 g / m ² or less with respect to the recording medium.   The inkjet recording apparatus according to claim 8, wherein the reactive component is a cationic substance.   The inkjet recording apparatus according to claim 8, wherein the reactive component includes at least one selected from ions of polyvalent metals and salts thereof.   The inkjet recording apparatus according to claim 12, wherein the polyvalent metal is at least one selected from Ca, Cu, Ni, Mg, Zn, Ba, Al, Fe, Cr, and Y. The inkjet recording apparatus according to claim 8, wherein the color material contains at least a pigment.

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