CN1933978A - Liquid composition, set of liquid composition and ink, ink-jet recording device and method for forming image - Google Patents

Abstract

An object of the present invention is to suppress curling of a recording medium coated with a liquid composition while ensuring ejection stability. The liquid composition of the present invention is a liquid composition used in an image recording method comprising: applying an ink containing a colorant in a dissolved or dispersed state on a recording medium; A step of applying a liquid composition that destabilizes the dissolved or dispersed state of the colorant in the ink by contacting the liquid composition, wherein the liquid composition contains at least polyvalent metal ions, Water, water-soluble organic compounds 1 and 2, and the content X (mass%) of the water-soluble organic compound 1 in the liquid composition is 15% by mass or more, and the water-soluble organic compound 1 is in the liquid composition The content X (mass %) of and the content Y (mass %) of the water-soluble organic compound 2 in the liquid composition satisfy a specific relationship.

Description

Liquid composition, set of liquid composition and ink, inkjet recording device, and image forming method

technical field

The present invention relates to a liquid composition, a set of liquid composition and ink, and an image recording method, and particularly relates to a liquid composition in the case of printing on a recording medium by using the liquid composition and ink in combination, and a set of the liquid composition and ink, an inkjet recording device, and an image forming method.

Background technique

As an inkjet recording method, there is proposed a proposal that, unlike the usual inkjet recording method, there is a liquid for making an image good, and an image is formed by adhering the liquid to a recording medium before ejecting the recording ink. Methods. For example, there is disclosed a method of recording an ink containing an anionic dye after attaching a liquid having a basic polymer (see, for example, JP-A-63-60783).

However, the above-mentioned method can suppress bleeding of an image and improve water resistance of the image by precipitating the dye itself on the recording medium, but the effect of suppressing bleeding between color inks of different hues is not sufficient. In addition, since the precipitated dye tends to be unevenly distributed on the recording paper, the uniformity of image quality is reduced. In particular, when plain paper is used as a recording medium or the like, since the covering property to pulp fibers is deteriorated, this tendency is clearly observed.

On the other hand, in systems using pigments as colorants for inks, in order to reduce bleeding in color prints, ink sets using inks containing pigment dispersions in combination with inks containing polyvalent metals have been proposed (see, for example, Japan Japanese Patent Application Laid-Open Publication No. 9-118850). In this case, it is restricted as follows: as the ink containing polyvalent metals, it is necessary to use polyvalent metals in consideration of the compatibility with the coloring material, that is, the stability of the ink, and thus it is difficult to obtain sufficient image density. question.

As a method for solving the above-mentioned problems, it has been proposed to print an ink having a property of reacting with the above-mentioned liquid composition after previously applying a liquid composition containing a polyvalent metal to a recording medium, thereby achieving image uniformity and image density improved recording method (hereinafter referred to as the two-liquid system). For example, it is disclosed that plain paper coated with a predetermined amount of a solution containing a dissociative polyvalent metal salt is used as recording paper, and that inkjet recording liquid having a specific acid value and containing a basic compound is used. An inkjet recording method in which printing is performed in the presence of a water-soluble resin dissolved in an aqueous medium, a pigment, and an ink having a specific surface tension (see, for example, Japanese Patent Application Laid-Open No. 2000-94825).

On the other hand, there is also a so-called curl phenomenon in which a recording medium to which moisture is applied is warped or curled. Conventionally, several methods have been proposed as a method for alleviating and suppressing the curl. For example, an inkjet ink comprising a solid substance having 4 or more hydroxyl groups in its molecular structure and being soluble in water or a water-soluble solvent has been proposed (see, for example, Japanese Patent Application Laid-Open No. 4-332775). In addition, inks containing sugars, sugar alcohols, and specific amide compounds as anti-curl agents have been proposed (see, for example, Japanese Patent Application Publication No. 6-157955, Japanese Patent Application Publication No. 6-240189, Japanese Patent Publication No. 9-16539). Gazette, Japanese Patent Application Laid-Open No. 9-176538). In addition, an ink containing a combination of a specific polyhydric alcohol and glycerin has been proposed (see, for example, Japanese Patent Application Laid-Open No. 10-130550). In addition, inks containing solvents, polymer binders, mordants, water-soluble anti-curl compounds, water-soluble desizing compounds, light-resistant compounds, defoamers, etc. have been proposed (see, eg, Japanese Patent Laid-Open No. 2000-19826).

Contents of the invention

The inventors of the present invention conducted detailed studies in order to obtain an image with suppressed image bleeding and excellent bleeding between color inks of different hues using a two-liquid system.

Methods of applying the liquid composition used in the two-liquid system onto a recording medium include various methods. Examples thereof include a method using an inkjet method like ink, and further examples include a roll coating method, a bar coating method, a spray coating method, and the like. In addition, as a method of applying the liquid composition and ink to the recording medium, the following methods are included.

(1) A method of applying a liquid composition to the entire surface of a recording medium.

(2) A method of selectively making the liquid composition adhere only to the image forming region and the vicinity of the image forming region where the ink adheres.

(3) A method in which the liquid composition and the ink are applied on a recording medium so as to be in contact with each other in a liquid state.

(4) A method of applying ink after fixing the liquid composition to the recording medium, that is, after droplets of the liquid composition are completely absorbed inside the recording medium.

As a result of studies conducted by the present inventors on these various coating methods, it was found that, after the liquid composition is coated on the entire surface of the recording medium, the method of applying the ink after the liquid composition is fixed to the recording medium, The resulting image has the best image characteristics such as density unevenness and fixation.

However, it was found that a new problem arises by using the above method. That is, since the liquid composition is applied over the entire surface of the recording medium, the recording medium bends and curls (curl phenomenon) more clearly than in the case of other methods. In particular, in a system in which a liquid composition is applied to a recording medium, the recording medium is then transported into a recording device, and the ink is then applied, recording is performed during the transport until the ink is applied to the recording medium coated with the liquid composition Media is curled, causing poor handling. Therefore, further suppression of curling than before has become a big problem.

Therefore, the object of the present invention is to provide a kind of ejection stability that can ensure the ejection stability required by the existing liquid composition after the ejection head is placed, and can ensure the ejection that will not cause problems such as disorder and blurring at the beginning of printing when printing is started. A liquid composition capable of alleviating and suppressing curl, a set of the liquid composition and ink, an inkjet recording device using the set of the liquid composition and ink, and an image forming method.

The above objects are achieved by the present invention as follows. That is, the liquid composition of the present invention is a liquid composition used in an image recording method comprising: applying an ink containing a colorant in a dissolved state or in a dispersed state on a recording medium; The process of applying a liquid composition to the recording medium, the liquid composition destabilizes the dissolved or dispersed state of the colorant in the ink by contacting the ink, wherein the liquid composition contains at least polyvalent Metal ions, water, water-soluble organic compound 1 and water-soluble organic compound 2, and the content X (mass %) of the water-soluble organic compound 1 is 15 mass % or more relative to the total amount of the liquid composition, and the water-soluble The content X (mass %) of the organic compound 1 relative to the total amount of the liquid composition and the content Y (mass %) of the water-soluble organic compound 2 relative to the total amount of the liquid composition satisfy the following relational formula:

0<Y/X≤0.9

The water-soluble organic compound 1 is a water-soluble compound having water-retaining properties whose difference between the water-retaining ability at a temperature of 23°C and a humidity of 45% and that at a temperature of 30°C and a humidity of 80% is 36% or less. organic compounds.

Water-soluble organic compound 2 is a water-soluble organic compound other than colorant and water-soluble organic compound 1.

In addition, the set of the liquid composition and ink of the present invention is characterized in that it is a set of the liquid composition and ink described above.

In addition, in the above-mentioned set of the liquid composition and the ink, the curling of the recorded matter can be prevented more effectively by the liquid composition and the ink satisfying the following conditions.

(condition)

50 g of the 800-fold diluted aqueous solution of the liquid composition and 0.3 g of the 5-fold diluted aqueous solution of the ink were mixed, and after 15 minutes were filtered through a filter of 0.2 μm, the maximum absorption wavelength in the visible light region (when using carbon black In the case of a pigment, the absorbance at a wavelength of 550nm) is denoted as (A), and the absorbance of the mixed solution of the 5 times diluted aqueous solution 0.3g of the water-based ink and 50g of pure water at the maximum absorption wavelength in the visible region is denoted as (B), (A) and (B) satisfy the following relationship:

(A)/(B)<0.85.

In addition, the inkjet recording device of the present invention is characterized in that it carries the liquid composition and ink described above.

In addition, the image forming method of the present invention is an image recording method including the steps of applying an ink containing a colorant in a dissolved state or a dispersed state on a recording medium, and applying a liquid composition to the recording medium, The liquid composition destabilizes the dissolved state or dispersed state of the colorant in the ink by contacting the ink, and is characterized in that:

The liquid composition at least comprises polyvalent metal ions, water, water-soluble organic compound 1 and water-soluble organic compound 2, and the content X (mass %) of the water-soluble organic compound 1 is relative to the total amount of the liquid composition. More than 15% by mass, the content X (mass %) of the water-soluble organic compound 1 relative to the total amount of the liquid composition and the content Y (mass %) of the water-soluble organic compound 2 relative to the total amount of the liquid composition satisfy the following Said relational formula:

0<Y/X≤0.9

The water-soluble organic compound 1 is a water-soluble compound having water-retaining properties whose difference between the water-retaining ability at a temperature of 23°C and a humidity of 45% and that at a temperature of 30°C and a humidity of 80% is 36% or less. organic compounds.

Water-soluble organic compound 2 is a water-soluble organic compound other than colorant and water-soluble organic compound 1.

In the case of using the liquid composition of the present invention as a liquid composition suitable for a two-liquid system, it is possible to ensure the stability of ejection after the ejection head is placed, and to ensure ejection with problems such as turbulence and blurring at the beginning of printing when printing is started stability while being able to suppress curling of the recording medium coated with the liquid composition. Therefore, even if it is used in a system in which the recording medium is transported into the recording device after applying the liquid composition to the recording medium, and then the ink is applied, transport failure due to curling of the recording medium can be eliminated. Furthermore, curling of an image obtained by applying ink to a recording medium coated with the liquid composition can be more effectively suppressed.

A brief description of the drawings

FIG. 1 is a schematic side sectional view of an example of an inkjet recording device.

2 is a front sectional view of a liquid composition remaining amount display portion provided in the inkjet recording apparatus of FIG. 1 .

3 is a schematic side cross-sectional view showing a state of replenishment of a liquid composition to the inkjet recording apparatus of FIG. 1 .

Fig. 4 is a schematic perspective view of an example of an inkjet recording device.

Fig. 5 is a longitudinal sectional view of an example of an ink cartridge.

Fig. 6 is a schematic plan view of a state where an ink cartridge is mounted on a recording head.

Fig. 7 is a schematic diagram of measurement results (difference due to environment) of water retention capacity of water-soluble organic compounds.

FIG. 8 is a schematic diagram showing the difference in water retention capacity of water-soluble organic compounds.

Detailed ways

Hereinafter, the present invention will be described in more detail by citing preferred embodiments.

[Water-soluble organic compound with water retention]

The curling after the aqueous liquid medium is applied to the recording medium is considered to be related to the evaporation of moisture applied to the recording medium. Therefore, the present inventors focused on the inkjet inks and coating liquids commonly used The water retention capacity of the water-soluble organic compounds was studied in detail as follows.

First, 20% by mass aqueous solutions of various water-soluble organic compounds were prepared, and 10 g of each was accurately weighed into a glass dish, and placed in an environment with a temperature of 23° C. and a humidity of 45%. In addition, pure water free of water-soluble organic compounds was also placed at the same time. As the water evaporates, the volume of the solution in the glass vessel decreases and then reaches a certain mass. At the same time, the glass dish containing only pure water has completely evaporated at this time, so the substance remaining in the glass dish containing water-soluble organic compounds can be regarded as the water-soluble organic compound and the moisture held by the substance. , through the following formula, calculate the water retention capacity of each compound.

Next, the above-mentioned glass dish was transferred to an environment with a temperature of 30° C. and a humidity of 80%, and waited until equilibrium was reached in the same manner. The residual weight in this environment was measured, and the water retention capacity was obtained from the above formula. Furthermore, the same glass dish was transferred again to an environment at a temperature of 23° C. and a humidity of 45%, and the residual weight was measured to determine the water retention capacity in the same manner. The results obtained are shown in Figure 7. In addition, the difference in water retention capacity under the two environments is shown in FIG. 8 .

The inventors of the present invention believe that there is a certain relationship between the difference in water retention capacity under the above-mentioned environment and the curling of plain paper. Therefore, when the aqueous solution containing the water-soluble organic compound studied above was coated on plain paper, and the occurrence of curl was checked, it was found that the water retention capacity at a temperature of 23°C and a temperature of 45% was the same as that at a temperature of 30°C and a humidity of 80%. The difference in the water retention capacity under the % environment is 36% or less and the water-soluble organic compound 1 significantly suppresses the curling. Therefore, inks containing only colorants and additives and these water-soluble organic compounds were further prepared, and the occurrence of curl was observed. As a result, it was found that curling did not occur even after being left at normal temperature for several days after printing.

However, when a liquid composition consisting only of the water-soluble organic compound 1 is loaded into an inkjet recording head that ejects liquid droplets from a nozzle, and is mounted on an inkjet recording device in this state and left for a long period of time, a problem occurs due to There are new problems such as poor ejection stability due to nozzle clogging, and disturbance at the beginning of printing when printing is started in a low-temperature and low-humidity environment.

Therefore, the inventors of the present invention conducted further studies in order to ensure the same level of ejection stability as that of conventional liquid compositions while controlling curling to a certain level or more. As a result, in the liquid composition, in addition to the water-soluble organic compound 1, polyvalent metals, and other water-soluble organic compounds other than the water-soluble organic compound 1 are contained, and more specifically, at a temperature of 23°C, The water-soluble organic compound 2 whose water-retaining capacity in an environment with a humidity of 45% and the water-retaining capacity in an environment with a temperature of 30°C and a humidity of 80% is more than 36% differs from the water-retaining capacity in an environment with a humidity of 45% and is included in a ratio satisfying the following conditions, so as to solve the above-mentioned problem.

0<Y/X≤0.9

(X: content (mass %) of water-soluble compound 1 relative to the total amount of the liquid composition, Y: content (mass %) of water-soluble compound 2 relative to the total amount of the liquid composition)

In addition, according to the research of the present inventors, in order to more effectively suppress the curling phenomenon of the recording medium coated with the liquid composition, in addition to the above conditions, the content X (mass %) of the water-soluble organic compound 1 must be controlled at It is 15% or more with respect to the liquid composition whole quantity.

In the present invention, the reason for controlling the content X (mass %) of the water-soluble organic compound 1 to the total amount of the liquid composition to be 15% or more is as follows. Even if the above-mentioned water-soluble organic compound 1 is 15% or less with respect to the total amount of the liquid composition, curling can be suppressed to some extent when the amount of the liquid composition applied to the recording medium is extremely large. However, the liquid composition used in the two-liquid system requires that the amount of the liquid composition applied to the recording medium be as small as possible in consideration of the fixability of the printed part after ink application and the like. In this way, when the application amount of the liquid composition to the recording medium is small, specifically, in order to suppress the curling phenomenon even when the application amount is 3.0 g/ ^m The content X (mass %) of the total amount of the liquid composition is controlled at least above 15 mass%.

In addition, the total content X+Y (mass %) of the water-soluble organic compound 1 and the water-soluble organic compound 2 is preferably 30 mass% or more based on the total amount of the liquid composition. In addition, from the viewpoint of curl performance, the water content is preferably 76% by mass or less, more preferably 71% by mass or less, based on the total amount of the liquid composition.

Furthermore, it is more preferable that the content Y (mass %) of the water-soluble organic compound 2 relative to the total amount of the liquid composition is Y<15 mass%, and the above-mentioned water-soluble organic compound 1 is selected from polyhydric alcohols and amide compounds. It is especially preferable that the water-soluble organic compound 1 is a polyhydric alcohol having an amide bond, and the molecular weight Mw of the water-soluble organic compound 1 is in the range of 100≦Mw≦1000.

In addition, as a result of various studies conducted by the present inventors using water-soluble organic compounds 1 and 2, it was found that by selectively using A water-soluble organic compound 1 that suppresses frizz. That is, when the application amount of the liquid composition to the recording medium is 10.0 g/m ² or more, and the content X (mass %) of the water-soluble organic compound 1 is less than 25 mass % relative to the total amount of the liquid composition, or In the case where the coating amount of the liquid composition to the recording medium is 10.0 g/m ^or more, and the water content is greater than 71% by mass relative to the total amount of the liquid composition, it is preferable to include a substance capable of suppressing curling of printed matter for a long period of time. The above-mentioned water-soluble organic compound 1-1, and the following water-soluble compound 1-2 capable of suppressing curling generated in a short period of time after printing. Especially under the above conditions, the difference in the curling phenomenon generated in a short time after printing was remarkable between the liquid composition containing the water-soluble organic compound 1-2 and the liquid composition not containing the water-soluble organic compound 1-2.

Water-soluble organic compound 1-1:

The molecular weight Mw is in the range of 100≤Mw≤1000, and

(A) Polyols with at least 3 or more ether bonds, or polyols with 3 or more OH groups, or at least 1 or more hydrophilic bonding groups (with hydrogen) in addition to OH groups and ether bond groups binding binding group) of polyols; and

(B) Water-soluble amide compound.

Water-soluble organic compound 1-2:

The molecular weight Mw is in the range of 100≦Mw≦150, and an alkanediol having OH groups at both ends of the main chain.

By using the liquid composition having the above-mentioned composition as the liquid composition used in the two-liquid system, it is possible to ensure the ejection stability required as a liquid composition, and at the same time, it is possible to alleviate and suppress curling.

On the other hand, when the method of applying the liquid composition on the recording medium is not the inkjet recording method but the method of applying the liquid composition to the recording medium by the roll coating method, a new problem arises: It is difficult to suppress evaporation of water from the liquid composition on the surface and the like, and the solid content in the liquid composition deposits on the surface of the roller and affects the image. Therefore, the present inventors have found that, even when a liquid composition is applied to a recording medium by a roll coating method or the like, curling can be suppressed, and further, the problem of precipitation of solid components on the surface of the roll, etc., which occurs as a new problem can be prevented. In the method, at least one of the water-soluble organic compound 1 and the water-soluble organic compound 2 is preferably used as a compound that is liquid in an environment with a temperature of 25° C. and a humidity of 40%. In addition, since at least one of the water-soluble organic compound 1 and the water-soluble organic compound 2 is a compound that is liquid at normal temperature (25° C.), the ejection stability after the inkjet head is left is also improved.

[liquid composition]

The components constituting the liquid composition of the present invention, physical properties, coating method and coating amount on the recording medium will be described in detail below.

(Water-soluble organic compound with water retention)

·Water-soluble organic compound 1

The water-soluble organic compound 1 of the present invention has a water-retaining ability in which the difference between the water-retaining ability at a temperature of 23°C and a humidity of 45% and that at a temperature of 30°C and a humidity of 80% is 36% or less of water-soluble organic compounds. In addition, the water-soluble organic compound 1 can be classified into the water-soluble organic compound 1-1 and the water-soluble organic compound 1-2 from the viewpoint of the curling property. More specifically, the following compounds can be mentioned. In addition, the so-called water-retaining water-soluble organic compound of the present invention specifically refers to a water-soluble organic compound having a water-retaining capacity of 5% or more in an environment at a temperature of 23°C and a humidity of 45%, according to the definition of the above-mentioned water-retaining capacity. compound.

·Water-soluble organic compound 1-1

The average molecular weight is 200 (the main component is tetraethylene glycol), 300 (the main component is hexaethylene glycol), 400 (the main component is nine ethylene glycol), 600 (the main component is triethylene glycol), 1000 ( The main components are polyethylene glycol such as behenyl glycol), 1,2,6-hexanetriol, trimethylolpropane, trimethylolethane, pentaerythritol, diglycerin, etc. Polyols, glucose, sorbitol, bishydroxyethyl sulfone, N, N-bis-(2-hydroxyethyl)-urea, tetrakis-(2-hydroxyethyl)-phthalamide, etc. have carbonyl, sulfone A polyol compound having a hydrogen-bonding group such as a group, an amide group, or the like. Among them, it is particularly preferable that the average molecular weight is 200 (the main component is tetraethylene glycol), 300 (the main component is hexaethylene glycol), 400 (the main component is nonaethylene glycol), 600 (the main component is triethylene glycol ), 1000 (the main component is behenyl glycol) and other polyethylene glycols, 1,2,6-hexanetriol, trimethylolpropane, bishydroxyethyl sulfone, N, N-bis-(2 -hydroxyethyl)-urea, more preferably N,N-bis-(2-hydroxyethyl)-urea.

·Water-soluble organic compounds 1-2

1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 3-methyl-1,5-pentanediol, 2-amino-2-methyl-1,3- An alkanediol having -OH groups at both ends of the carbon main chain which may have a substituent, such as propylene glycol, 2-amino-2-ethyl-1,3-propanediol, and the like. Among them, 1,5-pentanediol and 1,6-hexanediol are particularly preferable.

·Water-soluble organic compound 2

The water-soluble organic compound 2 in the present invention is a water-soluble organic compound other than the colorant and the water-soluble organic compound 1, that is, the water retention capacity in an environment with a temperature of 23°C and a humidity of 45% is the same as that of a temperature of 30°C, A water-soluble organic compound that has a water retention capacity difference of more than 36% in an environment with a humidity of 80% and does not satisfy the water-soluble organic compound 1 requirement. In addition, water-soluble colorants and the like are not included in the water-soluble organic compound 2 of the present invention. More specifically, the following compounds are mentioned. Examples include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, hexanediol and other alkylene glycols whose alkylene groups contain 2 to 6 carbon atoms; glycerin; 2-pyrrolidone; urea and ethylene glycol; A water-soluble compound having a hydrophilic group with a small number of carbon atoms, such as a radical urea. Among them, diethylene glycol, glycerin, 2-pyrrolidone, urea, and ethylene urea are particularly preferable.

Compounds such as urea and ethylene urea are preferable since their molecular weights are small, and the viscosity hardly increases even if they are added in a large amount. Compounds such as urea and ethylene urea can be used in combination with water-soluble compounds such as water-soluble organic solvents and dyes to be used as compounds having water-retaining properties in the present invention. In addition, the measurement result of the water retention capacity of ethylene urea in FIG. 7 (difference due to the environment) is the data when the test was performed using a dye.

In addition, in the present invention, at least one of the water-soluble organic compound 1 and the water-soluble organic compound 2 used in combination is preferably liquid at normal temperature (25° C.). This is to prevent the liquid composition from appearing due to the evaporation of the liquid composition in the case of using an inkjet method or a transfer method using a plurality of rollers as a method of applying the liquid composition of the present invention on a recording medium. Fixation between inkjet head parts, or between rollers.

(polyvalent metal ions and their salts)

Specific examples of polyvalent metal ions that can be preferably used in the liquid composition of the present invention include Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Mg ²⁺ , Zn ²⁺ , Sr ²⁺ , and Ba ²⁺ . Valence metal ions, trivalent metal ions such as Al ³⁺ , Fe ³⁺ , Cr ³⁺ and Y ³⁺ , but are not limited to these ions. In order to contain these polyvalent metal ions in liquid compositions, salts of polyvalent metals are used. The salt refers to a metal salt composed of the polyvalent metal ions listed above and anions that can combine with these ions, but must be soluble in water. Suitable anions for the formation of salts, starting from the solubility, include the conjugate bases of strong acids, such as the conjugate bases of strong acids nitric acid, sulfuric acid, hydrochloric acid NO ₃ ^- , SO ₄ ^2- , Cl ^- , especially NO ₃ ^- Since the solubility in water is excellent, it is preferable.

In addition, among these, it is known that a strong acid salt containing a metal ion having a high ability to destabilize components in the ink tends to cause a pH drop more easily. The present inventors use 4% by mass of carbon black dispersion aqueous solution (dispersant: styrene-acrylic acid, acid value 200, mass% of dispersant/mass% of pigment=0.2), with nitrates of various multivalent metal ions In the case of research, in the order of Fe ³⁺ , Y ³⁺ , Al ³⁺ >Cu ²⁺ , Ca ²⁺ >Mg ²⁺ , Sr ²⁺ , the ability to destabilize is high, and it is easy to cause decrease in pH. In the case of using a salt composed of these polyvalent metal ions and a strong acid, it is preferable to add Fe ³⁺ , Al ³⁺ , and Y ³ to the concentration of metal ions present in the liquid composition from the viewpoint of reactivity with ink. ⁺ is 0.2% by mass or more, Ca ²⁺ and Cu ²⁺ are 0.5% by mass or more, and Mg ²⁺ and Sr ²⁺ are 1.0% by mass or more.

In addition, among the salts formed with Mg ²⁺ and Sr ²⁺ which are less capable of destabilizing the ink, if desired, the salts with the same properties as the higher capable Fe ³⁺ , Al ³⁺ and Y ³⁺ salts can be obtained. ability, it is easy to cause the pH of the liquid composition to decrease over time.

In addition, in the present invention, the multivalent metal ion is preferably Ca ²⁺ , Mg ²⁺ , Sr ²⁺ , Al ³⁺ , and Y ³⁺ from the viewpoint of reactivity, colorability, and ease of handling, and more preferably Ca ²⁺ is preferred.

The content of the polyvalent metal ion in the liquid composition is preferably 0.01% by mass to 10% by mass relative to the total amount of the liquid composition. More preferably, it is 1.0% by mass to 5% by mass, and in order to fully exert the function of destabilizing the ink and to obtain a high level of image uniformity and optical density, it is preferable to contain more than 2.0% by mass to 4.0% by mass relative to the liquid composition. Valence metal ions. In addition, more than 10% by mass of polyvalent metal ions may be contained in the liquid composition. However, even if more than 10% by mass is added, a significant increase in the function of destabilizing the ink cannot be expected, and for these reasons, it is generally not necessary to contain it in excess.

(reason for changes due to saving)

When the liquid composition contains polyvalent metal ions, the liquid composition changes due to storage, high optical density cannot be obtained, and the image quality obtained at the initial stage and after a certain period of time may be different. The cause of the above phenomenon is presumed as follows.

Since the acid groups such as carboxyl groups produced by the oxidation of the organic compounds of the liquid composition react with polyvalent metal ions, the counter ions of the polyvalent metal ions (anions of polyvalent metals) and the protons of the above-mentioned acid groups generate acids, and the liquid is combined The pH of the substance decreases. If the pH of the liquid composition changes, the reactivity of the liquid composition also changes, and thus the resulting image quality also changes. For example, if the reactivity of the liquid composition is lowered, the colorant permeates into the recording medium, so high optical density cannot be obtained, and the colorant reaches near the back side of the recording medium (so-called offset of the colorant).

Therefore, the present inventors have found that, in the case of containing multivalent metal ions in the liquid composition, the liquid composition can be improved by simultaneously including the conjugate base of a strong acid and the conjugate base of a weak acid that has a buffering effect on the change of hydrogen ion concentration. It imparts a buffering effect and suppresses the drop in pH value as mentioned above to a minimum. In addition, the pH value in this invention is the value measured by the usual method at 25 degreeC.

The liquid composition of the present invention preferably has a pH of 2 or more. If the pH value is less than 2, the components in the liquid composition will corrode the surface of parts such as ink tanks and rollers, and the constituent components of the parts will dissolve in the liquid composition to adversely affect the image, which is not preferable. Preferably, the pH of the liquid composition is controlled within a range of 2-7, more preferably 3-6. If it is within this range, since the polyvalent metal ion can be more stably present in the liquid composition, the reactivity of the liquid composition can be sufficiently ensured, and the following buffering action can be sufficiently obtained, so the liquid composition can also be maintained. long-term stability of the substance.

(buffering effect on changes in hydrogen ion concentration)

The "effect of alleviating changes in hydrogen ion concentration" in the present invention means that when 1.0 ml of 0.1 N nitric acid aqueous solution is added to 50 ml of a liquid composition, the change in hydrogen ion concentration before and after addition of nitric acid aqueous solution is 1×10 ^-4 or less (hereinafter referred to as "buffering effect"). The change in hydrogen ion concentration can be calculated from the change in pH (hereinafter expressed as "change in hydrogen ion concentration"). When the initial pH value is denoted as a and the pH value after adding the nitric acid aqueous solution is b, the hydrogen ion concentration can be calculated by the following formula.

Change of hydrogen ion concentration (mol/L)=(10 ^-b )-(10 ^-a )

In the present invention, in order to obtain a buffering effect, it is preferable to include a buffering agent in the liquid composition. Preferable examples of the buffering agent include acetates such as sodium acetate, potassium acetate, and lithium acetate, hydrogen phosphate, hydrogen carbonate, or polybasic carboxylate hydrogen salts such as sodium hydrogen phthalate and potassium hydrogen phthalate. In addition, specific examples of the polycarboxylic acid include malonic acid, maleic acid, succinic acid, fumaric acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and phthalic acid in addition to phthalic acid. Phthalic acid, adipic acid, sebacic acid, dimer acid, pyromellitic acid, trimellitic acid, etc. In addition, as long as the pH value of the liquid composition can be maintained within a preferred range by adding the substance, any previously known compound having a buffering effect on the pH value can be used in the present invention. However, in the present invention, it is particularly preferable to use acetate as a buffering agent from the viewpoint of exhibiting a buffering action at an appropriate pH as the pH of the composition used together with the ink.

In addition, in addition, when a buffering agent is included in the ink in order to obtain a buffering effect, the metal ions from the buffering agent contribute to the destabilization of the coloring material of the ink, so in the case of using the above-mentioned liquid composition, it is possible to High optical concentrations are obtained that cannot be obtained with liquid compositions having only polyvalent metal ions. If the liquid composition of the present invention is used in image formation, the above-mentioned functions obtained by the above-mentioned liquid composition will synergize, not only can the curling of the printed matter be further suppressed, but also the liquid composition can be stabilized after a period of time from the initial stage of use. Images showing very high optical densities were obtained.

(physical properties)

The inventors of the present invention found that the more the toner aggregates in the recording medium exist in the surface layer portion, the more the degree of curling of the recorded matter obtained by the two-liquid system can be alleviated.

Controlling the reactivity between the liquid composition and the ink is exemplified as a condition for causing the aggregates to exist in a portion slightly permeated in the depth direction from the surface layer portion of the recording medium. In addition, it is very important that a sufficient amount of polyvalent metal ions for agglomerating the colorant exists in a large amount within about 30 μm from the surface layer portion of the recording medium. It is considered that in order to make the polyvalent metal ions contained in the liquid composition exist in a large amount within about 30 μm from the surface layer of the recording medium, the amount of the polyvalent metal ions contained in the liquid composition obviously has a great relationship, and in addition , The penetrability of the liquid composition to the recording medium and the coating amount also have a great relationship.

The liquid composition permeates along the fibers of the recording medium due to the influence of solvents, surfactants, etc. while in contact with the recording medium. In addition, it is considered that at the same time as this infiltration, the infiltrated liquid starts to evaporate, and a part of the polyvalent metal that has lost its solubility begins to precipitate. That is, since the reactivity of the liquid composition is improved with a small coating amount, penetration and evaporation of the liquid to the recording medium are promoted. As a result, a large amount of polyvalent metal ions may remain at the site where the portion penetrates from the surface layer of the recording medium to a slightly deeper direction.

As can be seen from the above, in order to ensure that the liquid composition of the present invention containing polyvalent metal ions has more effective impregnation properties on plain paper, the Ka value obtained by the Bristow method is preferably 1.3mL m ^-2 msec ^-1/2 Above, the coating amount is preferably 0.5g/m ² to 5g/m ² , more preferably the Ka value is 3.0mL·m ^-2 ·msec ^-1/2 or more, and the coating amount is preferably 2.0g/m ² to 3.0g /m ² .

(other ingredients)

In the liquid composition, in order to obtain a liquid composition with desired physical properties, surfactants, defoamers, antifungal agents, etc. can be appropriately added within the scope of not impairing the target effect of the present invention, and the added the effects of these.

(recording method, device)

The method of applying the liquid composition to the recording medium includes a method of using an inkjet recording method, a method of applying the liquid composition to the recording medium with a roller, and the like.

[ink]

The components constituting the ink of the present invention will be described in detail.

(Element)

The ink of the present invention can form a high-quality image by using it in combination with the liquid composition described above. In the ink, the colorant is preferably dispersed or dissolved through ionic groups in an aqueous medium.

(pigment)

Examples of the coloring material used in the ink of the present invention include pigments such as carbon black and organic pigments. A pigment can be used 1 type or in combination of 2 or more types. In addition, as the form of the pigment, a pigment dispersed with a dispersant, a self-dispersing pigment, colored fine particles/microcapsules, and the like can be used. Hereinafter, this will be described in detail.

·Carbon black

Specific examples of carbon black can use carbon black pigments such as furnace black, lamp black, acetylene black, and channel black, such as Raven 7000, Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 2000, Raven 1500, Raven 1250, Raven 1200, Raven 1190 ULTRA-II, Raven 1170, Raven 1255 (the above are manufactured by Columbia), Black Pearls L, Regal 400R, Regal 300R, Regal 660R, Mogul L, Monarch 700, Monarch800, Monarch 880, Monarch 900, Monarch 1000 , Monarch1100, Monarch 1300, Monarch 1400, Valcan XC-72R (manufactured by Cabot Corporation above), Color Black FW1, Color Black FW2, ColorBlack FW2V, Color Black FW18, Color Black FW200, ColorBlack S150, Color Black S160, Color Black S170 , Printex 35, Printex U, Printex V, Printex 140U, Printex 140V, SpecialBlack 6, Special Black 5, Special Black 4A, Special Black 4 (manufactured by デグツサ), No.25, No.33, No.40, No. 47, No. 52, No. 900, No. 2300, MCF-88, MA600, MA7, MA8, MA100 (the above are manufactured by Mitsubishi Chemical Corporation) and the like. Of course, it is not limited to these, and conventionally known carbon blacks can be used. In addition, magnetic fine particles such as magnets and ferrite, titanium black, and the like can also be used as the black pigment.

·Organic pigments

Specific examples of organic pigments include insoluble azo pigments such as toluidine red, toluidine purple, Hansa yellow, benzidine yellow, pyrazolone red, Lisol red, Heriot red, pigment scarlet, permanent red Soluble azo pigments such as 2B, derivatives obtained from vat dyes such as alizarin, indanthrene, and thioindigo, phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green, quinacridone red, quinacridone Quinacridone pigments such as magenta, pyrene pigments such as pyrene red and pyrene scarlet, isoindolinone yellow, isoindolinone orange and other isoindolinone pigments, benzimidazolone yellow, benzo Benzimidazolone pigments such as imidazolone orange and benzimidazolone red, pyranthrone pigments such as pyranthrone red and pyranthrone orange, thioindigo pigments, condensed azo pigments, thioindigo pigments, yellow Chthrein yellow, amide yellow, quinacridone yellow, nickel azo yellow, copper azomethine yellow, perillone orange, anthrone orange, dianthraquinone red, dioxazine violet and other pigments.

In addition, if the organic pigment is represented by the dye index (C.I.) number, the following pigments can be mentioned. Of course, conventionally known organic pigments other than the pigments described below may also be used.

C.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. 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. Pigment Blue: 15, 15:1, 15:3, 15:4, 15:6, 22, 60, 64

C.I. Pigment Green: 7, 36

C.I. Pigment Brown: 23, 25, 26

·Dispersant

When using the above-mentioned carbon black and organic pigment, it is preferable to use it in combination with a dispersant. As the dispersant, a dispersant capable of stably dispersing the above-mentioned pigment in an aqueous medium by the action of an anionic group is suitably used. Specific examples of the dispersant include, for example, styrene-acrylic acid copolymer, styrene-acrylic acid-alkyl acrylate copolymer, styrene-maleic acid copolymer, styrene-maleic acid-alkyl acrylate copolymer, benzene Ethylene-methacrylic acid copolymer, styrene-methacrylic acid-alkyl acrylate copolymer, styrene-maleic acid half ester copolymer, vinylnaphthalene-acrylic acid copolymer, vinylnaphthalene-maleic acid copolymer , styrene-maleic anhydride-maleic acid half ester copolymer or their salts. In addition, the weight average molecular weight of these dispersants is preferably 1,000 to 30,000, particularly preferably 3,000 to 15,000.

·Self-dispersed pigment

As the colorant, a pigment that can be dispersed in an aqueous medium without a dispersant by bonding an ionic group (anionic group) to the surface of the pigment, that is, a so-called self-dispersing pigment can be used. As such a pigment, self-dispersion type carbon black is mentioned, for example. Examples of the self-dispersing carbon black include anionic carbon blacks in which anionic groups are bonded to the surface of the carbon black.

·Anionic carbon black

Examples of the anionic carbon black include those in which at least one anionic group selected from -COOM, -SO ₃ M, -PO ₃ HM, and -PO ₃ M ₂ is bonded to the surface of the carbon black. In the above formula, M represents a hydrogen atom, alkali metal, ammonium or organic ammonium. Among them, especially carbon black charged anionicly by bonding -COOM or -SO ₃ M to the surface of carbon black has excellent dispersibility in ink, and is therefore particularly suitable for use in the present invention.

Wherein, in the groups represented by "M" in the above-mentioned hydrophilic groups, specific examples of alkali metals include Li, Na, K, Rb, and Cs, etc., and specific examples of organic ammonium include, for example, Methylammonium, dimethylammonium, trimethylammonium, ethylammonium, diethylammonium, triethylammonium, methylammonium, dimethanolammonium, trimethanolammonium, etc.

In addition, the ink of the present invention containing self-dispersing carbon black in which M is ammonium or organic ammonium can further improve the water resistance of recorded images, and is particularly suitable for use. This is considered to be due to the effect of ammonia gas evaporation due to the decomposition of ammonium when this ink is applied to a recording medium. Among them, among self-dispersing carbon blacks in which M is ammonium, for example, for self-dispersing carbon blacks in which M is an alkali metal, a substitution method in which M is replaced by ammonium using an ion exchange method, after adding an acid to form H-form A method in which ammonium hydroxide is added to change M into ammonium, etc.

The production method of anionic carbon black includes, for example, a method of oxidizing carbon black with sodium hypochlorite, by which a -COONa group can be chemically bonded to the surface of carbon black.

Among them, the above-mentioned various hydrophilic groups may be directly bonded to the surface of the carbon black. Alternatively, another atomic group may be inserted between the surface of carbon black and the aforementioned hydrophilic group to indirectly bond the aforementioned hydrophilic group to the surface of carbon black. Among them, specific examples of other atomic groups include, for example, linear or branched alkylene groups having 1 to 12 carbon atoms, substituted or unsubstituted phenylene groups, and substituted or unsubstituted naphthylene groups. Among them, the substituents of the phenylene group and the naphthylene group include, for example, straight-chain or branched-chain alkyl groups having 1 to 6 carbon atoms. In addition, examples of combinations of other atomic groups and hydrophilic groups include -C ₂ H ₄ COOM, -Ph-SO ₃ M, -Ph-COOM, etc. (wherein, Ph represents phenylene).

In the present invention, two or more of the above-mentioned self-dispersing carbon blacks may be appropriately selected and used as the coloring material of the ink. In addition, the amount of self-dispersing carbon black added to the ink is preferably 0.1% by mass to 15% by mass, particularly preferably 1% by mass to 10% by mass, based on the total amount of the ink. By setting it within this range, the self-dispersing carbon black can maintain a sufficient dispersion state in the ink. In addition to the self-dispersing carbon black, a dye may be added as a coloring material for the purpose of adjusting the color tone of the ink or the like.

·Colored particles/microencapsulated pigments

As the coloring material, in addition to the above-mentioned materials, pigments microencapsulated with polymers or the like, colored fine particles obtained by covering the periphery of resin particles with a coloring material, or the like can be used. The original microcapsules have dispersibility in an aqueous medium, and in order to improve the dispersion stability, the above-mentioned dispersant can further coexist in the ink. In addition, when colored fine particles are used as a colorant, it is preferable to use the above-mentioned anionic dispersant.

(aqueous medium)

The aqueous medium for dispersing the coloring material is not particularly limited as long as it can be used for ink. In addition, when ink is applied to a recording medium by an inkjet method (for example, Bubble Jet (registered trademark) method, etc.), it is preferable to adjust the viscosity and surface tension to have inkjet ejection characteristics.

The aqueous medium used in the ink of the present invention includes, for example, water or a mixed solvent of water and a water-soluble organic solvent. It is particularly preferable that the water-soluble organic solvent has an effect of preventing ink from drying. Specifically, alkanols having 1 to 4 carbon atoms such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, and tert-butanol; Amides such as methyl acetamide; ketones or ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; Diol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycerol, hexanediol, diethylene glycol and other alkylene glycols whose alkylene group contains 2 to 6 carbon atoms; polyethylene Lower alkyl ether acetates such as glycol monomethyl ether acetate; glycerin; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether Lower alkyl ethers of polyols such as ethers; polyols such as trimethylolpropane and trimethylolethane; N-methyl-2-pyrrolidone, 2-pyrrolidone, 1.3-dimethyl-2-imidazolidinone wait. The above-mentioned water-soluble organic solvents may be used alone or as a mixture. In addition, it is preferable to use deionized water (ion-exchanged water) as water.

The content of the water-soluble organic solvent contained in the ink of the present invention is not particularly limited, but is preferably 3% by mass to 50% by mass relative to the total amount of the ink. Also, the water content is 50% by mass to 95% by mass based on the total amount of the ink, preferably 82% by mass or less, more preferably 77% by mass or less, particularly preferably 72% by mass or less.

In addition, the water-soluble organic compound contained in the ink is the same as the liquid composition, and the difference between the water-retaining ability under the environment of temperature 23°C and humidity of 45% and the environment of temperature 30°C and humidity of 80% can be passed more. The water-soluble organic compound of 36% or less can further alleviate the curling after the ink is applied to the recording medium.

(other ingredients)

In the ink of the present invention, in addition to the above-mentioned components, a humectant may be added as needed. In order to maintain desired physical properties, a surfactant, an antifoaming agent, an anti-corrosion agent may also be added within the range that does not impair the target effect of the present invention. agent, antifungal agent, etc., and obtain the effect brought by the addition.

(hue of ink)

The color tone of the ink constituting the liquid composition and ink set is not particularly limited, and may be, for example, an ink showing at least one color tone selected from yellow, magenta, cyan, red, green, blue, and black. Specifically, the above-mentioned coloring materials can be selected appropriately so as to form an ink of a desired tone. Regarding the content of the coloring material of each ink, for example, in the case of inkjet recording, the above-mentioned ink has good inkjet ejection characteristics. Based on the total mass of the ink, it is preferably 1% by mass to 50% by mass. In addition, the content of water is preferably 50% by mass to 95% by mass relative to the total mass of the ink.

In addition, the ink used in combination with the liquid composition is not limited to one type, and it is more preferable to prepare an ink set suitable for forming a color image by combining two or more types of inks of different hues. In this case, at least one of the two or more inks may react with the liquid composition.

Among the inks constituting the ink set, at least one is an ink in which a coloring material is dispersed in an aqueous medium through the action of ionic groups, and the other inks may be inks containing a dye as a coloring material. Of course, all the inks may also be inks in which colorants are dispersed in an aqueous medium through the action of water-based groups. Such an ink set can suppress bleeding when inks of different color tones are applied adjacent to each other on a recording medium, which is a problem when forming a color image by an inkjet device.

More specifically, color bleeding, which becomes a problem in inkjet color images, is easily mixed with other color inks (for example, at least one selected from yellow ink, magenta ink, cyan ink, red ink, green ink, and blue ink). ink) will occur particularly significantly. Therefore, it is preferable to use in combination a black ink configured to disperse a colorant in an aqueous medium through the action of ionic groups and to interact with a liquid composition. And, in other color inks, it can be made into an ink that dissolves dyes in an aqueous medium. Of course, like black ink, it can be made into an ink that disperses colorants in an aqueous medium through the action of ionic groups.

[Set of liquid compositions and inks]

The inventors of the present invention conducted further studies to further improve the curling of recorded matter obtained by a two-liquid system using liquid and ink to form an image, and found that by making the ink and liquid composition applied to the recording medium satisfy the following conditions, Curling of the obtained recorded matter can be effectively suppressed.

(condition)

50 g of the 800-fold diluted aqueous solution of the liquid composition and 0.3 g of the 5-fold diluted aqueous solution of the ink were mixed, and after 15 minutes were filtered with a filter of 0.2 μm, the maximum absorption wavelength in the visible light region (using carbon black as In the case of pigments, the absorbance at a wavelength of 550 nm) is recorded as (A); the absorbance of a mixed solution of 0.3 g of a 5-fold diluted aqueous solution of the ink and 50 g of pure water at the maximum absorption wavelength in the visible light region is recorded as (B) , (A) and (B) satisfy the following relationship.

(A)/(B)＜0.85

The present inventors deduce the mechanism by which curling can be more effectively prevented in recorded matter obtained using the above-defined liquid composition and ink. The above relational formula specifies the reaction force of the liquid composition and the ink. By specifying the reactivity as described above, the aggregates generated by the contact of the polyvalent metal ions contained in the liquid composition and the coloring material contained in the ink are mostly present on the surface layer portion of the recording medium, so it can be suppressed when the ink is applied. The shrinkage of cellulose caused by moisture.

[Inkjet recording device]

Next, an example of a recording apparatus for forming an image using the above liquid composition and/or the above ink is given.

Fig. 1 is a schematic partial sectional view of one example of an inkjet recording apparatus. This image forming apparatus adopts the serial type inkjet recording method, therefore, includes a recording head 1, a paper feed tray 17 for supplying a recording medium (hereinafter sometimes referred to as recording paper) 19, and a liquid composition for coating the present invention. The paper feeding cassette 16 which is integrated with the components, the driving part which reciprocates the recording head in the direction perpendicular to the conveying direction of the recording paper, and the control part which controls the driving of these components.

The recording head 1 is mounted on the carriage 2 so that the surface on which the ink ejection ports are formed faces the platen 11 side. The recording head 1 (not shown) includes the ink ejection ports described above, a plurality of electrothermal transducers (for example, heating resistor elements) for heating the ink liquid, and a substrate supporting the electrothermal transducers. In addition, the recording head 1 has an ink cartridge installed in the upper carriage.

The carriage 2 mounts the recording head 1 and is capable of reciprocating movement along two guide shafts 9 extending parallel to the width direction of the recording paper 19 . In addition, the recording head 1 is driven synchronously with the reciprocating movement of the carriage to eject ink droplets on the recording paper 19 to form an image. Paper feeding cassette 16 is detachable from the main body of the image forming apparatus. Recording paper 19 is loaded on a paper feed tray 17 housed in the paper feed cassette 16 . When paper is fed, the uppermost sheet is pressed against the paper feed roller 10 by pressing the spring 18 of the paper feed tray 17 upward. The paper feed roller 10 is a roller having a substantially half-moon cross-sectional shape, is driven to rotate by an unshown motor, and only the uppermost sheet (recording paper 19 ) is fed by an unshown separation claw.

The dividedly fed recording paper 19 is conveyed along the conveyance surface of the paper feed cassette 16 and the conveyance surface of the paper guide 27 by the large-diameter intermediate roller 12 and the small-diameter applicator roller 6 in pressure contact therewith. These conveying surfaces consist of curved surfaces that can draw concentric arcs with the intermediate roller 12 . Accordingly, the recording paper 19 reverses its conveying direction by passing through these conveying surfaces. That is, the printing surface of the recording paper 19 faces downward until it is conveyed from the paper feed tray 17 to the intermediate roller 12 , but faces upward (the recording head side) when facing the recording head 1 . Therefore, the printing surface of the recording paper usually faces the outer direction of the image forming apparatus.

The liquid composition application unit is provided in the paper supply cassette 16, and includes a replenishing tank 22 for supplying the liquid composition 15, and an intermediate roller rotatably supported in a state where a part of the peripheral surface is immersed in the tank 22. 12. An applicator roller 6 which is arranged in parallel with the above-mentioned intermediate roller and which is in contact with the intermediate roller 12 and rotates in the same direction. In addition, the coating roller 6 is in circumferential contact with and parallel to the intermediate roller 12 for conveying the recording paper 19 . Therefore, when the recording paper 19 is conveyed, the intermediate roller 12 and the coating roller 6 rotate along with the rotation of the intermediate roller 12 . As a result, the liquid composition 15 is supplied to the peripheral surface of the coating roller 6 by the supply roller 13, and further uniformly applied to the recording paper sandwiched by the coating roller 6 and the intermediate roller 12 by the coating roller 6. 19 on the print side.

In addition, in this inkjet recording device, the float 14 is provided in the replenishing tank 22 . The float 14 is a substance having a lighter specific gravity than the liquid composition 15. By floating on the liquid surface of the liquid composition and passing through the remaining amount display window 21 as a transparent member, the liquid composition containing the reaction components can be visually confirmed from the outside. the remainder of the thing.

Fig. 2 is a front view of a remaining amount display portion. The remaining amount display portion is provided with marks indicating the degree of the remaining amount along the longitudinal direction of the remaining amount display window 21 . In the figure, when the liquid level of the liquid composition or the float 14 reaches the position marked "full", the tank is in a full tank state. On the other hand, when the liquid level of the liquid composition or the buoy 14 reaches the position marked "plus", it means that there is less liquid composition remaining. Therefore, the liquid composition 15 decreases slowly, and the liquid composition can be replenished when the float 14 is lowered to the "plus" line, which can be seen at a glance.

As shown in FIG. 3 , the liquid composition replenishment method is to insert the front end of the injection device 23 into the injection port 20 formed of a rubber member having an opening in the state when the paper feeding cassette 16 is pulled out from the image forming apparatus main body. The liquid composition is injected into the supplement tank 22.

In this way, the predetermined amount of recording paper coated with the liquid composition is then transported to the recording section by the main transport roller 7 and the pinch roller 8 in pressure contact therewith, and ink is applied by the recording head 1 . In the above structure, the recording sheet 19 that has been fed and printed is discharged and conveyed by the discharge roller 3 and the ratchet 4 in pressure contact therewith, and is stacked on the discharge tray 5 .

In addition, in the case of applying the liquid composition by a roller or the like, especially when the viscosity of the liquid composition is higher than that of the ink, the ink can be effectively stabilized with a small amount of application, and the fixability of the recorded matter, etc. Since it is also good, it is preferable. More specifically, the higher the viscosity of the liquid composition, the easier it is for the polyvalent metal ions to stay above the recording medium, and thus it is easier to efficiently react with the ink.

On the other hand, after the ink reacts with the liquid composition, it is preferable that the colorant component in the ink stays above the recording medium, and the solvent, water, etc. penetrate into the recording medium quickly, that is, solid-liquid separation is carried out rapidly, and thus from the recording medium. From the viewpoint of fixability and the like, the viscosity is preferably low. The viscosity of the liquid composition when the liquid composition is applied by a roller or the like is preferably 3 mPa·s to 100 mPa·s, more preferably 5 mPa·s to 60 mPa·s. The viscosity of the liquid composition or ink of the present invention is a value measured by a conventional method at 25°C.

In FIG. 4, another example of the inkjet recording apparatus is shown. In FIG. 4 , 61 is a scraper as a wiping member, and one end thereof is held fixed by a scraper holding member to form a cantilever state. The squeegee 61 is provided at a position adjacent to the recording area determined by the recording head 65 , and, in the case of the present embodiment, is held protruding into the moving path of the recording head 65 .

62 is the cover of the protruding mouth surface of the recording head 65, and its structure is: it is arranged on the original position adjacent to the scraper 61, and moves along the direction perpendicular to the moving direction of the recording head 65, and abuts against the ink ejection opening surface , to cover it. In addition, 63 is an ink absorber provided adjacent to the squeegee 61 , and like the squeegee 61 , it is kept protruding into the moving path of the recording head 65 . The ejection reciprocating member 64 is constituted by the scraper 61 , the cap 62 and the ink absorber 63 , and the wiper 61 and the ink absorber 63 remove moisture, dust, etc. from the ejection port surface. In addition, the ink of the recording head is sucked by a pump not shown in the figure through the cap, and then the ink at the ejection port of the liquid composition is sucked, so that the original ink of the recording head or the original ink and liquid composition are restored. Recovery system unit for jetting performance.

65 is a recording head having an ejection energy generating device and equipped with an ejection port to eject ink onto a recording medium facing the face of the ejection port for recording, and 66 is a carriage on which the recording head 65 is mounted and used to move the recording head 65 . The carriage 66 is slidably engaged with the guide shaft 67 , and a part of the carriage 66 is connected to a belt 69 driven by a motor 68 (not shown). Thus, the carriage 66 can move along the guide shaft 67, and can move in the recording area defined by the recording head 65 and the area adjacent thereto. 51 is a paper feed portion for inserting a recording medium, and 52 is a paper feed roller driven by a motor not shown in the figure.

With these structures, the recording medium is conveyed to a position facing the ejection port of the recording head 65, and is conveyed to a discharge portion provided with discharge rollers 53 as recording progresses. In the above structure, when the recording head 65 terminates recording and returns to the original position, the cap 62 of the ejection recovery portion 64 retracts from the moving path of the recording head 65, and the wiper 61 protrudes into the moving path. As a result, the ejection ports of the recording head 65 are wiped. In addition, when the cap 62 comes into contact with the ejection surface of the recording head 65 to cover it, 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 wiper 61 are in the same positions as those at the time of wiping. As a result, the ejection port surface of the recording head 65 is also wiped during this movement.

The above-mentioned movement of the recording head to the home position occurs not only when the recording is terminated or when the ejection is resumed, but also the recording head moves to the home position adjacent to the recording area at predetermined intervals during the movement of the recording area for recording, and is accompanied by this movement. Move to do the above wipe.

FIG. 5 is a schematic diagram of an example of a part for supplying ink or a liquid composition not containing a colorant to a recording head, for example, a cartridge 45 containing ink or a liquid composition supplied through a tube. Among them, 40 is a storage member for containing ink or liquid composition for supply, for example, a bag, and a rubber stopper 42 is provided at the front end thereof. By inserting a needle (not shown) in this plug 42, the ink or liquid composition in the bag 40 can be supplied to the recording head. 44 is an absorber for receiving waste ink or waste liquid composition. As the housing portion 40, the liquid contact surface with the ink or the liquid composition is preferably formed of polyolefin, especially polyethylene. Such a cartridge, for example, as shown in FIG. 4 , is structured to detachably constitute a recording head 901 for ejecting ink or a liquid composition. supplied to the recording head 901.

[Ink characteristics; inkjet ejection characteristics, permeability to recording medium]

The set liquid composition and ink of the present invention are particularly suitable for use in inkjet recording. As an inkjet recording method, include a recording method in which mechanical energy is applied to ink to eject liquid droplets, and a recording method in which thermal energy is applied to ink to eject liquid droplets through foaming of the ink, and not only the ink of the present invention can be used in these recording methods , and liquid compositions may be used. In this case, it is preferable that the above-mentioned liquid composition and ink of the present invention have the property of being ejectable from an inkjet head. From the point of view of the characteristics of inkjet head ejection, the characteristics of these liquids, for example, the viscosity is preferably 1 to 15 mPa·s, the surface tension is preferably 25 mN/m (dyne/cm) or more, and the viscosity is particularly preferably 1 to 5 mPa·s , surface tension 25 ~ 50mN/m (dyne/cm). In addition, the liquid composition of the present invention must only react with a specific ink on recording media such as paper, and therefore, it is preferable to control the surface tension of the liquid composition within the range that can be ejected from the inkjet head, and the ratio is by The surface tension of the ink whose liquid composition is destabilized is greater so that the liquid composition does not penetrate to other parts than the recording part of the specific ink.

Example

Hereinafter, the present invention will be described more specifically using Examples and Comparative Examples, but the present invention is not limited by the following Examples in any way within the range not exceeding the subject matter thereof. In addition, in the following description, unless otherwise specified, parts and % are based on mass.

[Evaluation of Liquid Composition]

(Preparation of liquid composition)

Various components shown in the following Table 1 were mixed, fully stirred and dissolved, and pressure-filtered through a microfilter (manufactured by Fuji Film) with a pore size of 1 μm to prepare liquid compositions 1-7. In addition, the unit is mass %.

Table 1 poor water retention molecular weight liquid composition 1 2 3 4 5 6 7 Trimethylolpropane 18.0 134.2 16.0 15.0 10.0 15.0 15.0 N,N-bis-(2-hydroxyethyl)-urea 27.4 148.2 16.0 15.0 glycerin 49.2 92.1 14.0 14.0 2.0 2.0 5.0 15.0 Ethylene urea 52.4 86.1 Calcium nitrate tetrahydrate - - 6.0 6.0 6.0 6.0 6.0 6.0 6.0 アセチレノ一ルEH(*) - - 1.0 1.0 1.0 1.0 1.0 1.0 1.0 ion exchange water - - 63.0 63.0 76.0 76.0 78.0 63.0 78.0 Y/X 0.88 0.88 0.13 0.13 0.50 1.00 0.00

(*) Acetylene glycol ethylene oxide adduct (surfactant) manufactured by Kawaken Fine Chemicals

In addition, the water retention rate of calcium nitrate tetrahydrate and Asecillenol EH contained in the above composition is less than 5%.

(curl's review)

The obtained liquid compositions 1 to 7 were applied to recording media using an inkjet recording apparatus having a service-type multi-recording head which ejects ink by applying thermal energy to the ink in accordance with a recording signal. In addition, the inkjet recording device used has an ejection amount per dot of 2.8pL, has a recording density of 2400×1200dpi, and is driven by a device with a drive frequency of 10kHz on A4-sized PPC paper (manufactured by Canon). On, apply evenly until the applied amount reaches 2.4g/m ² . The evaluation method of curl is as follows.

·Curl evaluation method

Under the conditions of temperature 24°C and humidity 50%, measure the amount of curl over time immediately after printing (within 1 minute), after 1 hour, after 1 day, 2 days, 3 days, and 7 days . When the printed paper is curled in the concave direction, it is marked as + (positive curl), and when it is curled in the convex direction, it is marked as - (negative curl), and the distance from the leading edge of the curled paper to the ground contact surface of the paper is measured using a ruler. . The criteria for judging curl are as follows. The evaluation results are shown in Table 2.

AA: Within ±10mm

A: greater than ±10mm, but within ±25mm

B: Greater than ±25mm, but within ±40mm

C: The state where the leading edge of the paper is turned inside the paper

D: The state where the front end of the paper is rolled to the inside of the paper surface

(Evaluation of ejection stability)

The obtained liquid compositions 1 to 7 were applied to recording media using an inkjet recording apparatus having a service-type multi-recording head which ejects ink by applying heat energy to the ink according to a recording signal. In addition, the inkjet recording device used has an ejection amount per dot of 2.8pL, has a recording density of 2400×1200dpi, and is driven by a device with a drive frequency of 10kHz on A4-sized PPC paper (manufactured by Canon). On, printing is performed so that the printing ratio becomes 100%. In addition, 2-step printing in which the printing area is scanned twice is performed. In addition, in order to confirm the printing state of the applied liquid composition, C.I. Direct Blue 199 was added as a colorant to the liquid composition. The added amount of the colorant was a small amount which did not affect the evaluation of jetting characteristics.

・Ejection stability 1 (ejection stability after the nozzle is placed) evaluation method

As the evaluation of the ejection stability of the liquid composition, in order to confirm whether there is a problem such as clogging of the nozzle, the above-mentioned liquid composition is packed in the inkjet head and left for 1 month, and then printed, and it is confirmed whether there is disorder of the image, fuzzy etc. The standard of ejection stability 1 (ejection stability after ejection head is placed) is as follows. The evaluation results are shown in Table 2.

A: No blurring occurs

B: Slightly blurred, but basically no problematic level

C: The level at which blurring occurs and the image has problems

D: Unable to spray

・Injection stability 2 (starting characteristics) evaluation method

As an evaluation of the ejection stability of the liquid composition, it was checked whether or not there was disorder and fog at the beginning of printing at the start of printing in Environment 1: normal humidity and normal temperature, and Environment 2: temperature 15° C., humidity 10%. The benchmarks for injection stability 2 (startup characteristics) are as follows. The evaluation results are shown in Table 2.

A: No blurring occurs

B: Blurring does not occur, and the image is slightly disturbed, but there is basically no problematic level

C: The beginning part is disturbed, and the image has a problematic level

D: The beginning is very blurry

Table 2 liquid composition curl evaluation jetting stability 1 jetting stability 2 immediately 1 hour later 1 day later 2 days later 3 days later 7 days later Environment 1 Environment 2 Example 1 1 AAA AAA AAA A A B B B D. 2 2 AAA AAA AAA A A B B B C 3 3 AAA AAA A A A A B B B 4 4 AAA AAA A A A A B B D. comparative example 1 5 A A B B B C B B D. 2 6 AAA A A B C C B B D. Reference example 1 7 AAA AAA AAA A A A D. B D.

(Evaluation of Sedimentability at the Time of Water Evaporation)

Various components shown in the following Table 3 were mixed, thoroughly stirred and dissolved, and then pressure-filtered using a microfilter (manufactured by Fuji Film) with a pore size of 1 μm to prepare liquid compositions 8 and 9. In addition, the unit is mass %.

table 3 Poor moisture retention molecular weight liquid composition 8 9 Trimethylolpropane 18.0 134.2 16.0 16.0 N,N-bis-(2-hydroxyethyl)-urea 27.4 148.2 glycerin 49.2 92.1 14.0 Ethylene urea 52.4 86.1 14.0 Calcium nitrate tetrahydrate - - 18.0 18.0 アセチレノ一ルEH(*) - - 1.0 1.0 ion exchange water - - 51.0 51.0 Y/X 0.88 0.88

(*) Acetylene glycol ethylene oxide adduct (surfactant) manufactured by Kawaken Fine Chemicals

Put the obtained liquid compositions 8 and 9, and 5 g each of the above-prepared liquid compositions 1 to 7 into a petri dish for measurement, and after standing for 30 days in an environment with a temperature of 25° C. and a humidity of 30%, visually inspect the The state of the liquid composition was observed, and the precipitation property when the water in the liquid composition evaporated was evaluated. The evaluation results are shown in Table 4.

Table 4 liquid composition Precipitate or not 1 none 2 none 3 none 4 none 5 none 6 none 7 have 8 none 9 have

[Evaluation of curling of recorded matter obtained by two-liquid system]

Next, curling of recorded matter obtained in a system (two-liquid system) in which ink was applied after applying the liquid composition was confirmed.

(preparation of ink)

Pigment dispersions 1 and 2 were prepared as described below. Using the obtained pigment dispersions 1 and 2, pigment inks were prepared. In the preparation of the pigment ink, each component was mixed according to the following Table 5, stirred well, and then filtered under pressure using a membrane filter (manufactured by Fujifilm) with a pore size of 0.3 μm to prepare inks 1 to 3.

·Pigment dispersion 1

10 parts of Monarch 880 (manufactured by Cabot Corporation) as a pigment, anionic polymer P-1 (styrene/M230G (methoxy polyethylene glycol methacrylate: manufactured by Shin-Nakamura Chemical Co., Ltd.)/acrylic acid copolymer ( Copolymerization ratio (mass ratio)=65/12/25), acid value 160, weight average molecular weight 8000, solid content 10% aqueous solution (neutralizer: potassium hydroxide)) 40 parts, pure water 50 parts mix, add to A batch-type vertical sand mill (manufactured by AIMEX) was filled with 250 parts of zirconia beads with a diameter of 0.3 mm, and the dispersion treatment was performed for 10 hours while cooling with water. Further, coarse particles are removed from the dispersion by a centrifuge. And, as a final preparation, a pigment dispersion 1 having a solid content of about 14.0% and a weight average particle diameter of 110 nm was obtained.

·Pigment dispersion 2

With 10 parts of Monarch 880 (manufactured by Cabot Company) as pigment, anionic polymer P-2 (styrene/acrylic acid copolymer (copolymerization ratio (mass ratio)=70/30), acid value 180, weight average molecular weight 10000, Solid content 10% aqueous solution, neutralizer: potassium hydroxide) 40 parts, pure water 50 parts are mixed, add to intermittent type vertical sand mill (manufactured by AIMEX), fill 150 parts of diameters and be the zirconia beads of 0.3mm, The dispersion treatment was performed for 10 hours while water cooling. Further, coarse particles are removed from the dispersion by a centrifuge. And, as a final preparation, a pigment dispersion having a solid content of about 14% and a weight average particle diameter of 110 nm was obtained. Add 30 parts of anionic polymer P-3 (styrene/acrylic acid copolymer (copolymerization ratio (mass ratio) = 87/13), acid value 100, weight average molecular weight 11000, solid content 10% aqueous solution to the above dispersion (neutralizing agent: potassium hydroxide)) to obtain pigment dispersion 2.

table 5 poor water retention molecular weight ink 1 2 3 Pigment Dispersion 1 - - 40.0 40.0 Pigment Dispersion 2 - - 40.0 polyethylene glycol 1000 18.9 1000 5.0 5.0 5.0 glycerin 49.2 92.1 5.0 diethylene glycol 39.7 118.2 5.0 7.5 7.5 Trimethylolpropane 18.0 134.2 3.0 3.0 アセチレノ一ルEH(*) - - 1.0 1.0 1.0 ion exchange water - - 44.0 43.5 43.5

(*) Acetylene glycol ethylene oxide adduct (surfactant) manufactured by Kawaken Fine Chemicals

(Manufacturing records with two-liquid system)

The liquid composition 8 was applied onto the recording medium by a roll coating method using a coating roll having the structure shown in FIG. 1 . In addition, 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 liquid composition to the recording medium became 2.4 g/m ² . In addition, PB paper (A4 size) manufactured by Canon Corporation was used as a recording medium.

Immediately after the application of the liquid composition, inks 1 to 3 were applied using an inkjet recording apparatus having a service-type multi-recording head that ejects ink by applying thermal energy to the ink according to a recording signal, and the following evaluations were performed. In addition, the inkjet recording device used has an ejection amount per drop of 2.8pL and a recording density of 2400×1200dpi, and the driving condition is to use a device with a driving frequency of 10kHz on the recording medium to which the liquid composition 8 is applied. Printing is performed so that the printing ratio becomes 100%. In addition, 2-step printing in which the printing area is scanned twice is performed.

(reactivity of ink and liquid composition)

Using the following set of liquid compositions and inks, they were mixed under the following conditions, the absorbance was measured, and the reactivity was evaluated. The results are shown in Table 6 below.

Mix 50 g of an 800-fold diluted aqueous solution of the above-mentioned liquid composition with 0.3 g of a 5-fold diluted aqueous solution of the above-mentioned ink, and filter it through a 0.2 μm filter after 15 minutes. The absorbance at 550 nm of a mixed solution of 0.3 g of a 5-fold diluted aqueous solution and 50 g of pure water was expressed as (B), and the value of (A)/(B) was obtained as a reactivity index.

Table 6 liquid composition ink Reactivity(A)/(B) 8 1 0.38 8 2 0.38 8 3 0.78

(curl's review)

The curl evaluation method is the same as when using a liquid composition. The evaluation results are shown in Table 7 below.

Table 7 liquid composition ink curl evaluation 1 hour later 1 day later 2 days later 3 days later 7 days later Example 5 8 1 A B B B C 6 8 2 A A A B C 7 8 3 A B B C C Reference example 2 8 - AAA AAA A A B 3 - 1 B C C C D. 4 - 2 B B B C D. 5 - 3 B B B C D.

In addition, the curling result of Reference Example 2 was superior to that of Example 4 in the evaluation from the start of printing to one day later.

Claims (13)

1. fluid composition that is used for image recording process, this image recording process possesses: apply with dissolved state on recording medium or comprise the operation of the ink of colorant with dispersity, and the operation that described recording medium is applied fluid composition, this fluid composition is by contacting dissolved state or the dispersity instabilityization that makes the colorant in the described ink with ink, it is characterized in that, described fluid composition comprises polyvalent metal ion at least, water, water-soluble organic compounds 1 and water-soluble organic compounds 2, and, the content X (quality %) of described water-soluble organic compounds 1 is more than the 15 quality % with respect to the fluid composition total amount, and described water-soluble organic compounds 1 satisfies following relational expression with respect to the content X (quality %) of fluid composition total amount and described water-soluble organic compounds 2 with respect to the content Y (quality %) of fluid composition total amount:

0＜Y/X≤0.9

Water-soluble organic compounds 1 be a kind of under the environment of 23 ℃ of temperature, humidity 45% water holding capacity and the difference of the water holding capacity under the environment of 30 ℃ of temperature, humidity 80% be water-soluble organic compounds below 36%, that have water-retaining property,

Water-soluble organic compounds 2 is a kind of water-soluble organic compounds except that colorant and water-soluble organic compounds 1.

2. fluid composition according to claim 1, wherein, described water-soluble organic compounds 2 is Y＜15 quality % with respect to the content Y (quality %) of fluid composition total amount, and described water-soluble organic compounds 1 is selected from polyalcohol, amide compound.

3. fluid composition according to claim 1 and 2, wherein, water-soluble organic compounds 1 is the polyalcohol with amido link, and the molecular weight Mw of water-soluble organic compounds 1 is positioned at the scope of 100≤Mw≤1000.

4. according to each described fluid composition of claim 1～3, wherein, at least one in described water-soluble organic compounds 1 and the water-soluble organic compounds 2 is liquid down at normal temperature (25 ℃).

5. according to each described fluid composition of claim 1～4, wherein, the content of water (quality %) is below the 71 quality % with respect to the fluid composition total amount.

6. complete fluid composition and ink is characterized in that, described fluid composition is each described fluid composition of claim 1～5.

7. complete fluid composition according to claim 6 and ink are complete fluid composition and the inks that satisfies following condition:

5 times of dilute aqueous solution 0.3g of 800 times of dilute aqueous solution 50g of described fluid composition, described ink are mixed, after the filter filtration with 0.2 μ m after 15 minutes, maximum absorption wavelength at visible region (is using under the situation of carbon black as pigment, wavelength is 550nm) under absorbance be designated as (A), when 5 times of dilute aqueous solution 0.3g of described water-base ink and the absorbance of mixed solution under the maximum absorption wavelength of visible region of pure water 50g are designated as (B), (A) with (B) satisfy following relational expression:

(A)/(B)＜0.85。

8. an ink-jet recording apparatus is characterized in that, is equipped with claim 1～5 each described fluid composition and ink.

9. image forming method is the image recording process that comprises following operation: apply with dissolved state on recording medium or comprise the operation of the ink of colorant with dispersity; And described recording medium applied the operation of fluid composition, this fluid composition is characterized in that by contact dissolved state or the dispersity instabilityization that makes the colorant in the described ink with ink,

Described fluid composition comprises polyvalent metal ion, water, water-soluble organic compounds 1 and water-soluble organic compounds 2 at least, and, the content X (quality %) of described water-soluble organic compounds 1 is more than the 15 quality % with respect to the fluid composition total amount, and described water-soluble organic compounds 1 satisfies following relational expression with respect to the content X (quality %) of fluid composition total amount and described water-soluble organic compounds 2 with respect to the content Y (quality %) of fluid composition total amount:

0＜Y/X≤0.9

Water-soluble organic compounds 1 be a kind of under the environment of 23 ℃ of temperature, humidity 45% water holding capacity and the difference of the water holding capacity under the environment of 30 ℃ of temperature, humidity 80% be water-soluble organic compounds below 36%, that have water-retaining property,

Water-soluble organic compounds 2 is a kind of water-soluble organic compounds except that colorant and water-soluble organic compounds 1.

10. image forming method according to claim 9, wherein, described water-soluble organic compounds 2 is Y＜15 quality % with respect to the content Y (quality %) of fluid composition total amount, and described water-soluble organic compounds 1 is selected from polyalcohol, amide compound.

11. according to claim 9 or 10 described image forming methods, wherein, water-soluble organic compounds 1 is the polyalcohol with amido link, and the molecular weight Mw of water-soluble organic compounds 1 is positioned at the scope of 100≤Mw≤1000.

12. according to each described image forming method of claim 9～11, wherein, at least one in described water-soluble organic compounds 1 and the water-soluble organic compounds 2 is liquid down at normal temperature (25 ℃).

13. according to each described image forming method of claim 9～12, wherein, the content of water (quality %) is below the 71 quality % with respect to the fluid composition total amount.

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