JP5483855B2 - Liquid composition, ink set, and inkjet recording method - Google Patents

Description

  The present invention relates to a liquid composition, an ink set having the liquid composition and a colored ink, and an ink jet recording method. More specifically, the present invention relates to a liquid composition that can provide a recorded matter excellent in color developability and glossiness of a recorded image when used with a colored ink, an ink set having the liquid composition and a colored ink, and an ink jet recording method.

  The ink jet recording method is a printing method in which a droplet of an ink composition is ejected and attached to a recording medium such as paper to perform recording. This method has a feature that a high-resolution and clear image can be printed at high speed while using a relatively inexpensive apparatus. In recent years, as the importance of improving image fastness in photo images increases, pigment inks are increasingly used for image recording on glossy recording media (hereinafter also referred to as glossy media). Various ideas have been made to further improve the color development and gloss of the recorded image obtained using the pigment ink.

  For example, Patent Document 1 discloses that the dispersion resin in the color ink and the aqueous polymer in the clear ink mutually interact so that the 60 ° specular gloss of the image formed by the color ink and the clear ink is substantially uniform. There is a disclosure relating to ink sets that belong to a common category. As another example, Patent Document 2 discloses a colorless ink for inkjet including a water-soluble polymer or a dispersed latex for printing on porous, hybrid gloss, and semi-gloss print media.

JP 2003-286428 A JP 2004-59933 A

  However, when ink jet recording is performed on glossy media such as glossy paper using pigment ink, the solid state in the ink accumulates on the paper surface, which changes the surface state, resulting in uneven gloss or reduced image clarity. Prone to occur. In recent years, in the market where high performance equivalent to that of silver halide photography is demanded, the technology disclosed in the above-mentioned literature does not reach a level that can sufficiently satisfy the market demand. .

  Specifically, first, in Patent Document 1, the range indicated by “dispersion resin and aqueous polymer belong to a common category” is ambiguous, and it is sufficient that the resin in the ink and the resin in the clear ink are the same. There is no disclosure regarding materials suitable for clear ink. The clear polymer aqueous polymer actually disclosed in the examples uses the same type of general resin as the dispersion resin in the ink. The present inventors have verified this material. As a result, it was found that the gloss of the recorded image was not sufficient. That is, it was found that when a clear ink containing this aqueous polymer is used, the aqueous polymer easily penetrates into the recording medium, and the effect of using the aqueous polymer does not appear. On the contrary, even if the aqueous polymer remains on the recording medium, the glossiness and image clarity of the recorded image are not the same as those of the silver salt photograph. Further, in the ink set disclosed in Patent Document 1, when a resin emulsion is used as the resin in the clear ink, the resin remains on the recording medium, but the image clarity of the recorded image is low and the photographic image quality is low. It was a level that could not be reached at all.

  In addition, Patent Document 2 also states that photographic image quality can be obtained using any material within the scope of disclosure. The picture quality level was not reached. As a result, when ink jet recording is performed on a glossy medium using ink, the present inventors need further great innovation to obtain a recorded image having high glossiness and image clarity equivalent to that of a silver salt photograph. I came to realize that there was.

  An object of the present invention is to provide a liquid composition that exhibits very excellent performance regarding glossiness and image clarity of a recorded image, an ink set having the liquid composition and a colored ink, and an ink jet recording method.

The above object is achieved by the present invention described below. That is, the present invention is a liquid composition used with a colored ink and applied to a recording medium, the liquid composition containing water, 1,2-alkanediol, and a graft copolymer, and , Does not contain a colorant, and the graft copolymer has a hydrophobic main chain and a hydrophilic side chain, and the hydrophobic main chain contains at least one selected from styrene, benzyl acrylate and benzyl methacrylate Weight average molecular weight of the graft copolymer obtained by polymerizing a monomer, the hydrophilic side chain obtained by polymerizing a monomer containing at least one selected from an acrylic acid macromonomer and a methacrylic acid macromonomer Is from 4,000 to 10,000, and the acid value of the graft copolymer is from 150 mgKOH / g to 250 mgKOH g or less, the content of the graft copolymer is 2.5% by mass or more and 4.0% by mass or less, and the content of the 1,2-alkanediol is 5.0% by mass or more and 8.0% by mass or less. And a ratio of the content of the 1,2-alkanediol to the content of the graft copolymer is 1.0 or more and 2.0 or less.

Yet another embodiment of the present invention, an ink set, characterized in that and a colored ink and the liquid composition of the present invention described above, the liquid composition and ionic said color ink is anionic It is.

  Another embodiment of the present invention is an ink jet recording method, wherein an image is recorded on a glossy recording medium using the above-described ink set of the present invention.

  According to the present invention, there is provided a liquid composition capable of forming an image having excellent glossiness and image clarity when image recording is performed on a recording medium having glossiness together with colored ink by an inkjet recording method. . Further, according to the present invention, there are provided an ink set and an ink jet recording method comprising the liquid composition and a colored ink.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments.
<Liquid composition>
The liquid composition of the present invention relates to a liquid composition for ink jet recording containing water, 1,2-alkanediol and a graft copolymer, and containing no colorant. In the present invention, the graft copolymer has a hydrophobic main chain obtained from styrene and / or benzyl (meth) acrylate and a hydrophilic side chain obtained from a (meth) acrylic acid macromonomer. The graft copolymer is a copolymer having a weight average molecular weight of 4,000 to 10,000 and an acid value of 150 mgKOH / g to 250 mgKOH / g. First, the technical idea that the above-described effects of the present invention can be obtained by using the liquid composition of the present invention will be described.

  FIG. 1 illustrates the permeation behavior of droplets when a liquid composition containing the graft copolymer that can be used in the present invention is applied to a glossy medium by ink jet recording. The graft copolymer that can be used in the present invention is bipolarized into a hydrophilic part (hydrophilic unit) and a hydrophobic part (hydrophobic unit) as described below, and the hydrophobic part is the main chain and the hydrophilic part is the side. A polymer that is a chain, that is, a polymer having a hydrophobic main chain and a hydrophilic side chain. Regarding the mechanism by which this graft copolymer has the same monomer type and composition ratio as the graft copolymer, and the gloss medium exhibits a higher glossiness than a random copolymer in which monomer units are present at random, the inventors have I think so.

  As shown in FIG. 1, the graft copolymer that can be used in the present invention penetrates in such a way that when it is applied to a glossy medium in a state of being contained in a liquid composition, the hydrophilic portion is oriented to the glossy medium side. Is thought to start. At that time, each molecule of the graft copolymer is regularly arranged in a state where the hydrophilic portion and the hydrophobic portion face each other, and therefore, it is considered that the interaction between the molecules is expressed in each of the hydrophilic portion and the hydrophobic portion (see FIG. 1). On the other hand, the random copolymer is not a structure in which the hydrophilic part and the hydrophobic part are bipolar as in the graft copolymer, and therefore, it is considered that the above-described interaction between molecules is difficult to develop. Due to such a difference in action, it is considered that the droplets containing the graft copolymer are less permeable to the glossy medium than the droplets containing the random copolymer. Thus, when the permeability to the glossy medium is small, a force in the direction in which the liquid spreads on the surface of the glossy medium acts on the droplets containing the graft copolymer. For this reason, in the liquid composition having the same solid content, when the graft copolymer is used, it is possible to form a thinly spread coating film on the surface of the glossy medium as compared with the case where the random copolymer is used. (See FIG. 1). In this way, the polymer component remains efficiently on the surface of the glossy medium, and a coating film with small surface irregularities is formed, so that the present inventors have formed an image with high glossiness and excellent image clarity. thinking.

  On the other hand, FIG. 2 shows the permeation behavior of droplets when a liquid composition containing a random copolymer having the same monomer type and composition ratio as the graft copolymer described in FIG. 1 is applied to a glossy medium by ink jet recording. , Explained. In this case, as shown in FIG. 2, since the arrangement of the monomer units in each molecule of the random copolymer is random, compared to the case of the graft copolymer, the droplets easily penetrate into the glossy medium. It is thought that it is difficult to spread thinly on the surface. For this reason, in this case, it is considered that the above-described effects obtained by including the graft copolymer in the liquid composition cannot be obtained. Also, among graft copolymers, the hydrophilic chain and the hydrophobic chain are mixed in the main chain and side chain, and the above effects are not obtained with a graft copolymer that is not bipolarized between the hydrophilic part and the hydrophobic part. I can't.

  Further, FIG. 3 shows an embodiment of the liquid composition of the present invention. That is, the penetration behavior of droplets when a liquid composition containing 1,2-alkanediol and the graft copolymer having the above-described structure is applied to a glossy medium by ink jet recording is described. The present inventors consider the mechanism by which the synergistic effect of this graft copolymer and 1,2-alkanediol is obtained as follows. First, as shown in FIG. 3, the graft copolymer and the hydrophilic portion of 1,2-alkanediol are oriented in the process of penetration of the liquid droplets into the glossy medium. In this case, not only the molecules of the graft copolymer are regularly arranged, but also the molecules of 1,2-alkanediol are regularly arranged between the molecules of the graft copolymer. Thereby, it is considered that a stronger interaction is expressed between the graft copolymer and each molecule of 1,2-alkanediol, and the penetrability of droplets into the glossy medium is further reduced. As a result, the present inventors presume that the effect of spreading the liquid is further enhanced on the surface of the glossy medium, and a coating film that is superior in terms of glossiness and image clarity is formed.

  FIG. 4 schematically shows how dots are formed after fixing the liquid composition. Specifically, FIG. 4 (a) shows a state of dot formation of the liquid composition containing the graft copolymer used in the present invention. FIG. 4B shows how dots are formed in the liquid composition of the present invention. FIG. 4C shows the dot formation of a liquid composition containing a random copolymer having the same monomer type and composition ratio, the same acid value, and the same molecular weight as the graft copolymer. FIG. 4D shows the dot formation of the liquid composition containing the random copolymer and 1,2 alkanediol. In addition, the polymer solid content of each liquid composition demonstrated by FIG. 4 (a)-(d) and the quantity of a water-soluble solvent are the same.

  First, as shown in FIG. 4A, when the graft copolymer is used due to the mechanism of the penetration behavior of the liquid composition described in FIG. To express. On the other hand, if only the graft copolymer is contained, the interaction between the molecules of the polymer is not large, and the effect of spreading the polymer thinly is limited. In addition, as shown in FIG. 4 (c), when the random copolymer is used, the polymer penetrates into the glossy medium, so the effect of the polymer is inefficient, and in some cases, the effect is completely exhibited. It will be in a state that does not. Further, even when 1,2-alkanediol is contained, if the graft copolymer defined in the present invention is not contained, the polymer hardly remains on the glossy medium as shown in FIG. Glossiness cannot be obtained. On the other hand, in the case of the liquid composition of the present invention, due to the synergistic effect of the graft copolymer and 1,2-alkanediol, as shown in FIG. It seems that it will remain and develop excellent glossiness and image clarity. Hereinafter, components constituting the liquid composition of the present invention will be described in detail.

(Graft copolymer)
In the graft copolymer used in the present invention, the hydrophobic main chain is obtained from styrene and / or benzyl (meth) acrylate, and the hydrophilic side chain is obtained from a (meth) acrylic acid macromonomer. That is, it has a structure having a hydrophobic part and a hydrophilic part soluble in an aqueous medium, wherein the hydrophobic part is a main chain and the hydrophilic part is a side chain. And the hydrophobic part which is a principal chain is manufactured from the above-mentioned hydrophobic ethylenically unsaturated monomer.

  The hydrophobic part contains a hydrophobic ethylenically unsaturated monomer other than styrene and / or benzyl (meth) acrylate to modify the physical properties of the graft copolymer, such as the glass transition temperature (Tg). You can also. Monomers useful as hydrophobic ethylenically unsaturated monomers other than styrene and / or benzyl (meth) acrylate include, for example: Acrylate or methacrylate alkyl esters, N-alkyl substituted acrylamides or methacrylamides, vinyl alkyl esters and the like. Some specific examples of such monomers include methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate. Further, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, styrene, α-methylstyrene, vinyl acetate, vinyl butyrate and the like are included.

  The hydrophilic part as a side chain is composed of a (meth) acrylic acid macromonomer because the graft copolymer is required to be soluble in the selected aqueous medium.

  If the hydrophilic ethylenically unsaturated monomer other than the (meth) acrylic acid macromonomer is used at a concentration that does not significantly change the solubility of the hydrophilic part in the selected aqueous medium, the hydrophilic part of the graft copolymer is used. Can be copolymerized. Some useful examples of hydrophilic ethylenically unsaturated monomers other than (meth) acrylic acid macromonomers include 1 to 12 carbon chain alkyl acrylates and alkyl methacrylates. More specifically, examples include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, acrylamide, and methacrylamide.

  The graft copolymer used in the present invention can be produced by the following method using a macromonomer. A macromonomer having a terminally polymerizable double bond is considered to be a side chain of the graft copolymer after the graft copolymer is produced. Examples of the method for producing a graft copolymer using a macromonomer include a method of first synthesizing a macromonomer and then copolymerizing the obtained macromonomer with a monomer selected for main chain synthesis. Specifically, first, a (meth) acrylic acid macromonomer to be a side chain is synthesized, and then the macromonomer is copolymerized with styrene and / or benzyl (meth) acrylate forming the main chain. The graft copolymer can be obtained. Hereinafter, a method for producing a macromonomer applicable to the present invention and a method for producing a graft copolymer using the macromonomer will be described in detail.

First, the macromonomer is most conveniently prepared by free radical polymerization using a catalytic or organic chain transfer agent that can be chain transferred by an addition fragmentation mechanism. Such chain transfer agents include cobalt (II) and cobalt (III) complexes. The organic chain transfer agent includes allyl sulfide, allyl bromide, dimer of methacrylic acid, dimer of α-methylstyrene and related compounds thereof. Cobalt complexes are preferred because they are effective not only in controlling the molecular weight of the polymer produced, but also in producing a polymer composition containing a very high percentage of macromonomers. Preferred cobalt chain transfer agents are disclosed in Janowicz et al. US Pat. No. 4,680,352 and Janowicz US Pat. No. 4,722,984. Cobalt chain transfer agents can be used in a concentration range of about 1 × 10 ⁻⁸ M to 5 × 10 ⁻³ M. The optimum concentration depends on the desired molecular weight and can be obtained by routine experimentation by those skilled in the art of polymerization. When the chain transfer agent is used in the above concentration range, a macromonomer having a molecular weight of 4,000 to 10,000, preferably 1,000 to 10,000 can be conveniently produced.

  Next, the graft copolymer can be obtained by copolymerizing the macromonomer obtained as described above with a monomer selected for the main chain through a conventional free radical polymerization method. The molecular weight of the final graft copolymer can be controlled in a number of ways known to those skilled in the art. The graft copolymer used in the present invention has a weight average molecular weight of 4,000 to 10,000.

  Moreover, a general organic solvent can be utilized as a polymerization medium for producing the macromonomer and the graft copolymer. These include, for example, alcohols such as methanol, ethanol, n-propanol and isopropanol. Ketones such as acetone, butanone, pentanone and hexanone. Tetrahydrofuran. Ethers such as diethyl ether. Commonly available ethylene glycol and polyethylene glycol. Monoalkyl and dialkyl ethers such as cellosolve. Examples include, but are not limited to, carbitol, acetic acid, propionic acid and alkyl esters of butyric acid, and mixtures thereof. Mixtures of low molecular weight alcohols such as ethanol and isopropanol and low molecular weight ketones such as acetone are particularly useful for producing macromonomers with a high acid content.

  Commonly used azo polymerization initiators are both macromonomers and graft copolymers, as long as they are soluble in the solution of the solvent and monomer mixture and have an appropriate half life at the polymerization temperature. Suitable for manufacturing. A “suitable half-life” as used herein is a half-life of about 10 minutes to 4 hours. Some examples of such initiators include 2,2'-azobis (isobutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (methyl Butyronitrile) and 1,1′-azobis (cyanocyclohexane). In addition, non-azo initiators including benzoyl peroxide and lauroyl peroxide can be used as long as they do not adversely react with the chain transfer agent under the macromonomer reaction conditions.

  The graft copolymer used in the present invention that can be produced by the method as described above needs to have a weight average molecular weight of 4,000 to 10,000. By setting the weight average molecular weight within the above range, it is possible to leave a water-based polymer on the surface of the recording medium and to form a film having excellent image clarity. Furthermore, it is preferably 3,000 or more and 6,000 or less. The graft copolymer used in the present invention is required to have an acid value of 150 mgKOH / g or more and 250 mgKOH / g or less. By setting the acid value within the above range, a film having a high glossiness can be formed on the surface of the recording medium. Furthermore, it is preferable that they are 180 mgKOH / g or more and 220 mgKOH / g or less. The graft copolymer is preferably neutralized using KOH (potassium hydroxide) or the like in an amount of 0.8 molar equivalent or more and 1.2 molar equivalent or less with respect to the actually measured acid value. In the present invention, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the graft copolymer can be determined from a size exclusion chromatography method (GPC method) according to JIS handbook chemical analysis K0124. In the present invention, the acid value can be determined by potentiometric titration.

  The content (B) of the copolymer in the liquid composition of the present invention needs to be 2.5% by mass or more and 4.0% by mass or less based on the total mass of the liquid composition. By setting the content (B) of the copolymer in the above range, a film having both high glossiness and excellent image clarity can be formed. If the amount is less than 2.5% by mass, the polymer component hardly remains on the surface of the glossy medium, so the effect of the present invention cannot be obtained. If it exceeds 4.0% by mass, a large amount of the polymer component remains on the paper surface and the unevenness becomes large, so that the effect of the present invention cannot be obtained.

(1,2-alkanediol)
The liquid composition of the present invention needs to contain 1,2-alkanediol as a water-soluble solvent. Examples of the 1,2-alkanediol that can be used in the present invention include 1,2-hexanediol and 1,2-pentanediol. In the present invention, the 1,2-alkanediol content (A) needs to be 5.0% by mass or more and 8.0% by mass or less based on the total mass of the liquid composition. By setting the content (A) of 1,2-alkanediol in the above range, sufficient interaction with the polymer can be obtained, and the liquid permeability to the recording medium can be reduced. Thereby, a film having excellent glossiness and image clarity can be formed. When the content is less than 5.0% by mass, since the solvent component is small, the synergistic effect of the polymer and the solvent cannot be obtained. On the other hand, when the content exceeds 8.0% by mass, it is difficult to print the liquid composition with high accuracy, and as a result, the surface unevenness becomes large, so that the effect of the present invention cannot be obtained.

  Furthermore, in the present invention, the ratio (A / B) of the content of the 1,2-alkanediol (A) and the graft copolymer (B) based on the total mass of the liquid composition is 1.0 or more and 2 Must be less than or equal to 0.0. By setting the mass ratio (A / B) of the 1,2-alkanediol and the copolymer within the above range, an exquisite film having higher gloss and excellent image clarity is formed on the recording medium. can do. When (A / B) is less than 1.0, the synergistic effect of the polymer and the solvent cannot be obtained, and the silver salt level is not reached. On the other hand, when (A / B) exceeds 2.0, it becomes difficult to print the liquid composition with high accuracy, and as a result, the surface unevenness becomes large, so that the effect of the present invention cannot be obtained.

(Other solvents)
Moreover, as a solvent other than 1,2-alkanediol to be contained in the liquid composition of the present invention, any solvent can be used as long as it can be suitably used for an ink or a liquid composition. For example, the water-soluble solvent mentioned as a specific example in the description regarding the following colored ink can be used. Among these, glycerol is mentioned as a preferable solvent from a viewpoint used together with 1, 2- alkanediol.

(water)
In the present invention, it is desirable to use deionized water as the water. The content of water contained in the liquid composition of the present invention is preferably in the range of 50% by mass to 95% by mass based on the total mass of the liquid composition.

(Other additives)
In addition to the polymer and the aqueous medium, the liquid composition of the present invention may contain a surfactant, a pH adjuster, a pH buffer, an antifungal agent, and the like as necessary. The liquid composition of the present invention is a so-called clear ink that does not contain a colorant. However, if it is not substantially contained, the liquid composition may not be completely colorless and may exhibit a light color.

<Colored ink>
The colored ink for recording an image on a glossy medium together with the liquid composition of the present invention is not particularly limited, but preferably contains a pigment as a colorant. The colored ink is at least one selected from yellow ink, magenta ink, and cyan ink, and is used as an ink set of a liquid composition and colored ink. Hereinafter, components of the colored ink (hereinafter sometimes simply referred to as “ink”) will be described.

(Pigment)
Examples of the pigment that can be used include carbon black and organic pigments. It is also possible to use one kind of various pigments or a combination of two or more kinds. The pigment content in the ink is preferably 0.1% by mass or more and 15.0% by mass or less, more preferably 1.0% by mass or more and 10.0% by mass or less, based on the total mass of the ink.

(Carbon black)
Examples of the carbon black include carbon black pigments such as furnace black, lamp black, acetylene black, and channel black. Specifically, for example, Raven 7000, Rayvan 5750, Rayvan 5250, Rayvan 5000, Rayvan 3500, Rayvan 2000, Rayvan 1500, Rayvan 1250, Rayvan 1200. Ray Van 1190 ULTRA-II, Ray Van 1170, Ray Van 1255 (manufactured by Columbia). Black Pearls L, Regal 400R, Legal 330R, Legal 660R, Mogul L, Monarch 700, Monak 800, Monak 880, Monak 900, Monak 1000. Monak 1100, Monak 1300, Monak 1400, Valcan XC-72R (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 (Degussa) No. 25, no. 33, no. 40, no. 47, no. 52, no. 900, no. 2300, MCF-88, MA600, MA7, MA8, MA100 (manufactured by Mitsubishi Chemical Corporation) and the like can be used. However, it is not limited to these, and any conventionally known carbon black can be used. Further, magnetic fine particles such as magnetite and ferrite, titanium black and the like may be used as the black pigment.

(Organic pigment)
Specifically, the following can be used as the organic pigment. For example, insoluble azo pigments such as toluidine red, toluidine maroon, Hansa Yellow, Benzidine Yellow, and pyrazolone red. Soluble azo pigments such as Ritolol Red, Helio Bordeaux, Pigment Scarlet, and Permanent Red 2B. Derivatives from vat dyes such as alizarin, indanthrone and 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 pigments such as isoindolinone yellow and isoindolinone orange. Imidazolone pigments such as benzimidazolone yellow, benzimidazolone orange, and benzimidazolone red. Pilanthrone pigments such as pyranthrone red and pyranthrone orange. Thioindigo pigment. Condensed azo pigment. Thioindigo pigment. Examples include flavanthrone yellow, acylamide yellow, quinophthalone yellow, nickel azo yellow, copper azomethine yellow, perinone orange, anthrone orange, dianthraquinonyl red, dioxazine violet, and the like.

  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, 155, 166,168. C. I. Pigment Orange 16, 36, 43, 51, 55, 59, 61. C. 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. 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. Pigment Green 7, 36. C. I. Pigment Brown 23, 25, 26 and the like can be exemplified. Of course, any conventionally known organic pigments other than those described above can be used.

(Pigment dispersant)
In the ink used in the present invention, a dispersant is preferably used in combination with the above-described carbon black or organic pigment. 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. A 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 2,000 to 30,000, and particularly preferably in the range of 3,000 to 10,000. Further, the mass ratio of the pigment and the dispersant in the ink is preferably adjusted to a range of 10/200 or more and 10/2 or less. The content of the dispersant in the ink is preferably 0.1% by mass or more and 5.0% by mass or less based on the total mass of the ink.

(Water-soluble solvent)
The ink used in the present invention is preferably an aqueous medium such as water, and a water-soluble solvent is used for the purpose of stable use in the ink jet recording method. When adhering to a recording medium by an ink jet recording method (for example, bubble jet (registered trademark) method), the ink may be prepared to have a desired viscosity and surface tension so as to have excellent ink jet discharge characteristics. preferable.

  Examples of the water-soluble solvent that can be contained in the ink used in the present invention include the following. Alkyl alcohols having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol; Alkanediols such as 1,2-pentanediol, 1,2-hexanediol, 1,5-pentanediol, 1,6-hexanediol. 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. Alkylene glycols in which the alkylene group contains 2 to 6 carbon atoms, such as 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol and the like. Lower alkyl ether acetates such as polyethylene glycol monomethyl ether acetate. Glycerin. Lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether. Polyhydric alcohols such as glycerin, trimethylolpropane, 1,2,6-hexanetriol, trimethylolethane. In addition, N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like can be mentioned, but are not limited thereto. The water-soluble solvents as described above can be used alone or as a mixture. Moreover, it is desirable to use deionized water as water.

  The content of the water-soluble solvent contained in the ink used in the present invention is not particularly limited, but a range of 10% by mass to 40% by mass is preferable based on the total mass of the ink. The content of water contained in the ink is preferably in the range of 50% by mass to 95% by mass based on the total mass of the ink. Preferably it is 82 mass% or less, More preferably, it is 77 mass% or less, More preferably, it is 72 mass% or less.

(Other additives)
The ink used in the present invention can contain a surfactant, a pH adjuster, a pH buffer, an antifungal agent and the like as necessary.

<Characteristics of liquid composition and ink>
The liquid composition of the present invention and the colored ink used together with the liquid composition are used in an ink jet recording method for forming an image by ejecting ink to form dots. As an ink jet recording method, there are 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 that case, it is preferable that the above-described liquid composition or ink of the present invention has such a characteristic that it can be discharged from a recording head of an ink jet recording apparatus. From the viewpoint of dischargeability from the recording head of the ink jet recording apparatus, it is preferable to prepare the characteristics of the liquid composition and the ink as follows. For example, these viscosities are preferably 1 mPa · s or more and 15 mPa · s or less, and more preferably 2 mPa · s or more and 5 mPa · s or less. Further, the surface tension is preferably 25 mN / m (dyne / cm) or more and 45 mN / m (dyne / cm) or less, more preferably 28 mN / m or more and 35 mN / m or less.

<Glossy recording medium>
Examples of the glossy recording medium used in the present invention include so-called glossy paper such as PR paper (manufactured by Canon Inc.) and super photo paper SP101 (manufactured by Canon Inc.).

<Ink set>
The ink set of the present invention is an ink set having the above-described liquid composition of the present invention and the above-described colored ink, wherein the ionicity of the liquid composition and the colored ink is anionic.

<Inkjet recording method>
The inkjet recording method of the present invention is characterized in that an image is recorded on a glossy medium using the above-described ink set of the present invention. In the ink jet recording method of the present invention, it is preferable to adjust the amount of the liquid composition applied in accordance with the amount of ink applied.

<Inkjet recording apparatus>
FIG. 5 shows an example of an ink jet recording apparatus. In FIG. 5, 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 a discharge recovery unit 64, and the blade 61 and the ink absorber 63 remove moisture, dust, and the like from the discharge port surface. Further, each ink of the recording head, and further, ink positioned at the discharge port of the liquid composition is sucked by a pump (not shown) through a cap, and the original ink of the recording head, or ink and liquid It constitutes a recovery unit that restores the original ejection performance of the composition.

  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 discharge port surface of the recording head 65, 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-described movement of the recording head 65 to the home position is not only at the end of recording or at the time of ejection recovery, but also at the home position adjacent to the recording area at a predetermined interval while the recording head 65 moves the recording area for recording. The wiping is performed along with this movement.

<Ink cartridge>
FIG. 6 is a diagram illustrating an example of a cartridge 45 containing a member that supplies a liquid composition that does not contain ink or a color material to the recording head, for example, an ink or a liquid composition supplied via a tube. . Here, reference numeral 40 denotes an accommodating portion, for example, a bag, in which ink or liquid composition for supply is accommodated, and a rubber stopper 42 is provided at the tip thereof. By inserting a needle (not shown) into the stopper 42, the ink or liquid composition in the bag 40 can be supplied to the head. Reference numeral 44 denotes an absorber for receiving waste ink or waste liquid composition. The container 40 preferably has a liquid contact surface with the ink or liquid composition formed of polyolefin, particularly polyethylene. For example, as shown in FIG. 7, such a cartridge is configured to be detachable from a recording head 901 that discharges ink or a liquid composition. The cartridge 45 is configured such that ink or a liquid composition is supplied to the recording head 901 in a state where the cartridge 45 is mounted on the recording head 901.

  EXAMPLES Hereinafter, although an Example, a comparative example, and a reference example demonstrate this invention concretely, these do not limit the scope of the present invention at all. In the following description, “part” or “%” is based on mass unless otherwise specified. Further, the remainder (remaining amount) refers to the remainder obtained by subtracting each component from 100 parts (100%) as a whole.

(Polymer synthesis)
Table 1 shows the polymers used in the liquid compositions of Examples and Comparative Examples. Polymers 1 to 6 which are graft copolymers were synthesized with reference to JP-A No. 10-87768. Specifically, the synthesis was performed by the following method.

(Preparation of macromonomer 1)
First, the macromonomer 1 which becomes a side chain unit of the graft polymer was prepared as follows. 20 g of methacrylic acid was used as a raw material for the macromonomer 1 forming the side chain unit. Further, 4 g of α-methylstyrene dimer was used as a chain transfer agent, and 0.4 g of ABNE (2,2′-azobis (2-methylbutyronitrile) azobisisobutyronitrile) was used as a radical polymerization initiator. Then, radical polymerization was performed in 300 parts of IPA (isopropyl alcohol) while dropping the above raw materials over 3 hours at a polymerization temperature of 110 ° C. under N ₂ reflux. After completion of the dropping, the polymerization reaction was carried out at 110 ° C. for 3 hours. Then, it cooled to room temperature, the unreacted substance was removed by precipitation refinement | purification, and it dried under reduced pressure, and obtained the macromonomer 1. At this time, the weight average molecular weight of the macromonomer 1 was 600.

(Production of polymer 1)
Using 23 parts of the macromonomer 1 having an anionic functional group obtained above, Polymer 1 was prepared by the following method. The macromonomer 1 is dissolved in advance in 300 parts of IPA (isopropyl alcohol), and a mixture of the monomer constituting the main chain unit described below and the following polymerization initiator is added dropwise to polymerize. Went. The following three types of monomers were used as monomers constituting the main chain unit. 62 g of BzMA (benzyl acrylate) and 15 g of BuMA (butyl methacrylate) were used. Further, 4 parts of ABNE (2,2′-azobis (2-methylbutyronitrile) azobisisobutyronitrile) was used as the radical polymerization initiator. And the mixture was dripped in IPA (isopropyl alcohol) which melt | dissolved the macromonomer 1 prepared previously, and radical polymerization was performed. At this time, the polymerization temperature was 110 ° C., and the dropping time was 3 hours under N ₂ reflux. After this dropping was completed, the reaction system was further maintained at 110 ° C. for 3 hours to carry out a polymerization reaction. Thereafter, the reaction system was cooled to room temperature, unreacted substances were removed by precipitation purification, and dried under reduced pressure to obtain polymer 1. The obtained dispersion resin A1 is a graft copolymer having a structure in which the main chain unit is a hydrophobic segment and the side chain unit is a hydrophilic segment. The weight average molecular weight of this polymer 1 was 6,050, and the acid value was 157 mgKOH / g.

(Production of polymers 2 to 6)
In the preparation of polymer 1, the composition ratios of monomers and macromonomers were adjusted, and polymers 2 to 6 were synthesized in the same manner. The composition ratio, molecular weight, and acid value of the monomer and macromonomer at that time are shown in Table 1.

  Moreover, the polymer 7 which is a random copolymer was synthesized by the method shown below. First, 150 g of IPA (isopropyl alcohol) was added to a flask equipped with a stirrer, a nitrogen inlet tube, a reflux condenser, and a thermometer, and the temperature was raised to 85 ° C. in a nitrogen atmosphere. Next, 3 types of a mixed solution of 61 g of BzMA, 16 g of BuMA and 23 g of MAA, a solution in which 0.8 g of MTG as a chain transfer agent was dissolved in 10 g of IPA, and a solution in which 0.5 g of ABNE was dissolved in 5 g of IPA were added dropwise over 2 hours. After completion of the dropwise addition, the reaction was continued for 3 hours for synthesis. BzMA is benzyl methacrylate, BuMA is butyl methacrylate, MTG is 2-mercaptoethanol, ABNE is 2,2′-azobis (2-methylbutyronitrile). is there.

  After the synthesis, the synthesized polymers 1 to 7 were determined for weight average molecular weight (Mw) by gel permeation chromatography. Polystyrene was used as the standard substance and tetrahydrofuran was used as the solvent. The acid value was determined by potentiometric titration using 0.1N-KOH. After adding a proper amount of KOH and water in an equimolar amount with respect to the acid value of the polymer and stirring the resulting solutions of polymers 1 to 7, the solvent was removed under reduced pressure, and water was added to obtain 25% by mass. An aqueous polymer solution was obtained. Table 1 shows the structures, compositions, and physical properties of the polymers 1 to 7 synthesized by the above method.

(Preparation of liquid composition)
Liquid compositions each having the composition shown in Table 2 below were prepared. Specifically, the components shown in Table 2 below were mixed using the composition shown in Table 2 and mixed by stirring sufficiently to dissolve, followed by pressure filtration with a microfilter (Fuji Film FR20). . In Table 2, “A” indicates the content of 1,2-alkanediol used in the present invention in the liquid composition, and “B” indicates polymers 1 to 4 (graft copolymer defined in the present invention). In the liquid composition, “A / B” indicates a mass ratio thereof. Further, the ionicity of the obtained liquid composition was all anionic.

(Preparation of ink set)
<Preparation of Bk dispersion>
10 parts of black pigment, 30 parts of anionic polymer (styrene-acrylic acid random copolymer, acid value 200 mgKOH / g, weight average molecular weight 9,000, aqueous solution with a solid content of 20%, neutralizer: potassium hydroxide), pure 60 parts of water were mixed. Next, this was charged into a batch type vertical sand mill (manufactured by Imex), charged with 200 parts of 0.3 mm diameter zirconia beads, and dispersed for 5 hours while cooling with water. The resulting dispersion was centrifuged to remove coarse particles, and a Bk dispersion having a final preparation with a solid content of about 16% and a weight average particle size of 70 nm was obtained. The black pigment used was carbon black (product name: Monac 1100, manufactured by Cabot Corporation).

<Preparation of Cyan dispersion>
10 parts of cyan pigment, 30 parts of anionic polymer (styrene-acrylic acid random copolymer, acid value 200 mg KOH / g, weight average molecular weight 9,000, aqueous solution with a solid content of 20%, neutralizer: potassium hydroxide), pure 60 parts of water were mixed. Next, this was charged into a batch type vertical sand mill (manufactured by Imex), charged with 200 parts of 0.3 mm diameter zirconia beads, and dispersed for 5 hours while cooling with water. The resulting dispersion was centrifuged to remove coarse particles, and a Cyan dispersion having a final preparation with a solid content of about 16% and a weight average particle size of 90 nm was obtained. The cyan pigment used was Pigment Blue 15: 3 (product name: Toner Cyan BG, manufactured by Clariant).

<Preparation of Magenta dispersion>
10 parts of magenta pigment, 30 parts of anionic polymer (styrene-acrylic acid random copolymer, acid value 200 mgKOH / g, weight average molecular weight 9,000, aqueous solution with a solid content of 20%, neutralizer: potassium hydroxide), pure 60 parts of water were mixed. Next, this was charged into a batch type vertical sand mill (manufactured by Imex), charged with 200 parts of 0.3 mm diameter zirconia beads, and dispersed for 5 hours while cooling with water. After the resulting dispersion was centrifuged to remove coarse particles, a final Magenta dispersion having a solid content of about 16% and a weight average particle size of 84 nm was obtained. The magenta pigment used is Pigment Red 122 (product name: Jet Magenta DMQ, manufactured by Ciba Specialty Chemicals).

<Preparation of Yellow Dispersion>
10 parts of yellow pigment, 30 parts of anionic polymer (styrene-acrylic acid random copolymer, acid value 200 mg KOH / g, weight average molecular weight 9,000, aqueous solution with a solid content of 20%, neutralizer: potassium hydroxide), pure 60 parts of water were mixed. Next, this was charged into a batch type vertical sand mill (manufactured by Imex), charged with 200 parts of 0.3 mm diameter zirconia beads, and dispersed for 5 hours while cooling with water. After the dispersion was centrifuged to remove coarse particles, a yellow dispersion having a final preparation with a solid content of about 16% and a weight average particle size of 65 nm was obtained. The yellow pigment used is Pigment Yellow 74 (product name: Hansa Brilliant Yellow 5GX70, manufactured by Clariant).

<Preparation of ink>
Using the obtained dispersion of each color, each ink of black, cyan, magenta, and yellow was prepared with the following ink composition. As a specific preparation method, the following components were mixed, sufficiently stirred and dissolved, and each ink was then prepared by pressure filtration with a micro filter having a pore size of 3 μm (Fuji Film FM300). As the acetylene glycol ethylene oxide adduct, acetylin EH (trade name: manufactured by Kawaken Fine Chemical Co., Ltd.) was used. The ionicity of each of the obtained inks was anionic.

(Ink composition of Bk ink)
・ Bk dispersion 25%
・ Glycerin 15%
・ 1,2-hexanediol 5%
・ Acetylene glycol ethylene oxide adduct 1%
-Residual amount of water The viscosity of the Bk ink was 2.5 mPa · s in a 25 ° C environment.

(Ink composition of Cyan ink)
・ Cyan dispersion 25%
・ Glycerin 15%
・ 1,2-hexanediol 5%
・ Acetylene glycol ethylene oxide adduct 1%
-Water remaining amount The viscosity of Cyan ink was 2.3 mPa * s in 25 degreeC environment.

(Ink composition of Magenta ink)
・ Magenta dispersion 30%
・ Glycerin 15%
・ 1,2-hexanediol 5%
・ Acetylene glycol ethylene oxide adduct 1%
-Water remaining amount The viscosity of Magenta ink was 2.8 mPa * s in 25 degreeC environment.

(Ink composition of Yellow ink)
・ Yellow dispersion 35%
・ Glycerin 15%
・ 1,2-hexanediol 5%
・ Acetylene glycol ethylene oxide adduct 1%
-Water remaining amount The viscosity of Yellow ink was 3.0 mPa * s in 25 degreeC environment.

(Evaluation of liquid composition)
A plurality of color inks (all four colors of yellow, magenta, cyan, and black) obtained above in an inkjet recording printer BJF900 (manufactured by Canon Inc.) and a liquid composition that is a clear ink shown in Table 2 Each was loaded. This printer can be used with six types of inks. However, in this evaluation test, any one of the four color inks obtained above and the liquid composition obtained above was used. The space (one type) for mounting the remaining ink was not used. Using this printer, Super Photo Paper SP101 (manufactured by Canon Inc.), which is a glossy medium, was used as a recording medium, and first, a solid of 50 mm × 50 mm region was printed only for the liquid composition. The driving amount of the liquid composition was set to 10 ng at 600 dpi square. About each obtained clear image, the 20 degreeC glossiness and image clarity were measured with the following method. Moreover, from these measurement results, each liquid composition was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 3. Table 3 shows the evaluation results when no liquid composition is printed as Reference Example 1. As can be seen from the evaluation results shown in Table 3, it was confirmed that the liquid composition of the present invention exhibited 20 ° glossiness and image clarity similar to silver salt photographs when recorded on a glossy medium. A micro haze meter (BYK Gardner) was used for measurement of 20 ° gloss. In addition, the image clarity measurement apparatus DIAS (manufactured by qea) was used.

·Evaluation criteria:
A: 20 ° glossiness of 80 or more and image clarity of 4.5 or more.
(Glossiness at or above silver halide photography).
○: 20 ° glossiness of 80 or more and image clarity of 4.0 or more and less than 4.5.
(Glossiness on the same level as silver halide photography).
Δ: 20 ° glossiness of less than 80 or image clarity of less than 4.0.
(Glossiness not comparable to silver halide photography.)
X: Less than 20 degree glossiness 80 and image clarity less than 4.0.
(Glossiness that does not reach silver halide photography.)

<Evaluation with liquid composition and ink set>
Using the ink composition consisting of the liquid composition of Example 2 or Comparative Example 1 and the four color inks prepared above, an image was printed on the glossy medium SP101 using the inkjet recording printer BJF900 in the same manner as described above. Printed. Ink printing is performed for each ink of Bk, Cyan, Magenta, and Yellow in an area of 50 mm × 50 mm with an implantation amount of 0% Duty, 25% Duty, 50% Duty, 75% Duty, 100% Duty. Each went. Further, printing with the liquid composition was performed in an area of 50 mm × 50 mm with a 50% duty shot when the ink shot was 0% duty, 25% duty, and 50% duty. In addition, when the ink shot amount was 75% Duty, a 25% Duty shot amount was applied to an area of 50 mm × 50 mm, and when the ink shot amount was 100% Duty, printing was not performed (see Table 4). In this embodiment, 100% duty means that 20 ng is given per 600 dpi. The liquid composition and the ink were printed in the same scan.

  About each obtained color image, the 20 degree glossiness and image clarity were measured by the same method described above. From the obtained measurement results, the liquid compositions of Example 2 and Comparative Example 1 were evaluated according to the following evaluation criteria. The evaluation results are shown in Table 4. Table 5 shows the evaluation results when the liquid composition is not printed at all as Reference Example 2 (only ink is printed).

·Evaluation criteria:
◯: The 20 ° glossiness of each color image is 80 or more and the image clarity is 4.0 or more, and they are uniform throughout the image.
(Glossiness equivalent to photo quality.)
Δ: The 20 ° glossiness of each color image is 60 to 100, and there is variation in the entire image, and / or the image clarity of each color image is 3.0 to 5.0, and there is variation in the entire image. is there.
(Glossiness not comparable to silver halide photography.)
X: The 20 ° glossiness of each color image is 15 to 100, and there is considerable variation in the entire image, and / or the image clarity of each color image is 1.0 to 5.0, and variation in the entire image. There are quite a few.
(Glossiness that does not reach silver halide photography.)

  As can be seen from the evaluation results, when the liquid composition of the present invention is recorded on a glossy medium together with a colored ink, a full-color image similar to a silver salt photograph is obtained due to the synergistic effect of 1,2-alkanediol and the graft copolymer. 20 ° glossiness and image clarity can be obtained.

1 schematically illustrates a process in which droplets of a liquid composition containing a graft copolymer that can be used in the present invention penetrate into a glossy medium. 3 schematically illustrates a process in which droplets of a liquid composition containing a random copolymer penetrate into a glossy medium. 3 schematically shows a process in which droplets of the liquid composition of the present invention penetrate into a glossy medium. FIG. 2 schematically shows a fixing state of the liquid composition on the glossy medium at the time when the liquid composition has landed on the glossy medium and the penetration of the liquid component has been completed. (A) shows the liquid composition containing the graft copolymer used for this invention. (B) shows the liquid composition of the present invention. (C) shows a liquid composition containing a random copolymer. (D) shows a liquid composition containing a 1,2-alkanediol and a random copolymer. It is a schematic perspective view which shows an example of the inkjet recording device of this invention. It is a longitudinal cross-sectional view which shows an example of an ink cartridge. FIG. 3 is a schematic plan view showing a state in which the ink cartridge according to one embodiment of the present invention is mounted on a recording head.

Claims (4)

A liquid composition used with a colored ink and applied to a recording medium,
The liquid composition contains water, 1,2-alkanediol, a graft copolymer, and no colorant,
The graft copolymer has a hydrophobic main chain and a hydrophilic side chain;
The hydrophobic main chain is obtained by polymerizing a monomer containing at least one selected from styrene, benzyl acrylate and benzyl methacrylate,
The hydrophilic side chain is obtained by polymerizing a monomer containing at least one selected from an acrylic acid macromonomer and a methacrylic acid macromonomer,
The weight average molecular weight of the graft copolymer is 4,000 or more and 10,000 or less,
The graft copolymer has an acid value of 150 mgKOH / g or more and 250 mgKOH / g or less,
The content of the graft copolymer is 2.5% by mass or more and 4.0% by mass or less,
The 1,2-alkanediol content is 5.0% by mass or more and 8.0% by mass or less,
A liquid composition, wherein a ratio of the content of the 1,2-alkanediol to the content of the graft copolymer is 1.0 or more and 2.0 or less.   The liquid composition according to claim 1, wherein the 1,2-alkanediol is at least one selected from 1,2-hexanediol and 1,2-pentanediol.   An ink set comprising the liquid composition according to claim 1 or 2 and a colored ink, wherein the ionicity of the liquid composition and the colored ink is anionic.   An inkjet recording method comprising: recording an image on a glossy recording medium using the ink set according to claim 3.

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