JP2001181539A - Aqueous recording liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous recording liquid having a balanced ink character required for an aqueous ink for ink-jet recording and writing such as keeping a stable viscosity under a wide temperature environment of usage and not agglomerating composing elements of the recording liquid for a long time. SOLUTION: In an aqueous recording liquid formed by blending an aqueous additive to a main component comprising a dye, a pigment, and an aqueous medium resolving or dispersing them, this aqueous recording liquid contains a cellulose, as an aqueous additive, having an average polymerization degree (DP) of 100 or less, a ratio of cellulose I type component of 0.1 or less, a ratio of cellulose II type component of 0.4 or less, and an average diameter of the cellulose particle of 5 μm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous recording liquid such as an ink jet recording liquid or an aqueous recording liquid for a writing instrument.
More specifically, as an aqueous additive, the average degree of polymerization (DP) is 100 or less, and the fraction of cellulose type I crystal component is 0.1%.
Hereinafter, the fraction of the cellulose type II crystal component is 0.4 or less, and the average particle size of the constituting cellulose particles is 5 μm.
The present invention relates to an aqueous recording liquid containing cellulose, characterized in that:

[0002]

2. Description of the Related Art Conventionally, aqueous recording liquids include a dye-soluble aqueous ink obtained by dissolving a dye as a coloring agent in water or an aqueous solvent such as an organic solvent / water mixed solvent, and carbon black and aniline as coloring agents. There is a pigment-dispersed aqueous ink in which a pigment such as black is dispersed in an aqueous solvent. In each case,
It is necessary that the ink has a proper viscosity as an ink under various temperature environments, and that the components maintain a uniform state without causing aggregation. In order to achieve these, it is customary to incorporate various additives into the ink composition. For example, Japanese Unexamined Patent Publication No. Hei.
Japanese Patent Publication No. -5703 and Japanese Patent Publication No. Hei 8-19361 disclose a technique for increasing the stability of an ink using a coloring agent such as carbon black or aniline black by adding a water-soluble polymer to reduce the cohesiveness of the coloring agent. It has been disclosed.

[0003] These water-soluble polymers can simultaneously control the viscosity of the ink, but cannot necessarily exhibit a constant viscosity under a wide temperature environment. For example, in many cases, when the temperature becomes high, the viscosity decreases, and the viscosity of the ink cannot be kept constant. Furthermore, the function as a dispersion stabilizer is not suitable for a wide range of colorants because of compatibility with the colorant. More specifically, for example, required in the field of inkjet recording, not to clog the fine ejection nozzle,
Inks that satisfy well-balanced ink physical properties such as good scratch resistance of printed matter, no aggregation or sedimentation of constituent components during storage at high temperature for a long period of time, and no solid content precipitation Not provided.

[0004] Further, almost the same problems occur in writing stationery using water-based ink such as a ball-point pen, that is, poor dispersion stability of components, prevention of ink solidification at the pen tip, prevention of ball-pen ball wear, and the like. However, satisfactory results have not been obtained. As an attempt to provide an aqueous recording liquid that can solve these problems, Japanese Patent Application Laid-Open No. H5-171094 discloses an example in which cellulose is used as an additive. However, as in the case of the cellulose fine particles described in this example, the dispersion of the cellulose fine particles generally has high whiteness (high opacity) even when the particle size is extremely small. There is also a problem that the sharpness of the surface is remarkably impaired, that is, glossiness is reduced without a sense of transparency.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, that is, to maintain stable viscosity under a wide range of operating temperature environments and to coagulate the components of the recording liquid for a long time. An object of the present invention is to provide a water-based recording liquid satisfying well-balanced ink characteristics required for water-based ink for ink-jet recording and writing, for example, without causing the ink to be printed.

[0006]

Means for Solving the Problems The present inventors have made the above PC
In the invention of T / JP98 / 05462, a transparent to translucent cellulose dispersion is obtained. The present inventors have studied the application of the above invention as an additive for an aqueous ink composition, and found that this cellulose dispersion is extremely effective as an additive for maintaining stable viscosity under a wide range of temperature environments. At the same time, it was found that the components in the ink prepared by blending the same did not cause aggregation and sedimentation for a long time, did not change the ink characteristics, and did not precipitate solids. Due to the high transparency, compared with the case where a conventional cellulose additive is added, the aqueous recording liquid using the same has high uniform dispersibility of fine particles, and the printing surface using the same is higher. The inventors have found that they have sharpness, and have reached the present invention. The above object is achieved by the present invention described below.

That is, the present invention relates to (1) an aqueous recording medium comprising a dye or a pigment and an aqueous medium in which the dye or pigment is dissolved or dispersed as a main component, and an aqueous additive mixed with the dye or pigment. If the degree (DP) is 100 or less,
The fraction of the cellulose type I crystal component is 0.1 or less, the fraction of the cellulose type II crystal component is 0.4 or less, and the average particle diameter of the constituting cellulose particles is 5 μm or less. Aqueous recording liquid characterized by (2)
The aqueous recording liquid of (1), wherein the aqueous recording liquid contains 0.05 to 5% by weight of cellulose as an aqueous additive, and (3) the aqueous recording liquid is an ink for inkjet recording.
Or (2) the aqueous recording liquid of (1) or (2), wherein the aqueous recording liquid is an ink for a writing instrument;
It is.

Hereinafter, the present invention will be described in detail. The present invention relates to an aqueous recording liquid comprising a dye or a pigment and an aqueous medium in which the dye or pigment is dissolved or dispersed and containing an aqueous additive, and having an average polymerization degree (DP) of 100 or less as an aqueous additive. Contains a cellulose having a fraction of the cellulose type I crystal component of 0.1 or less, a fraction of the cellulose type II crystal component of 0.4 or less, and an average particle diameter of the constituting cellulose particles of 5 μm or less. An aqueous recording liquid characterized in that:

The cellulose used in the present invention is preferably supplied as a cellulose dispersion dispersed in a dispersion medium obtained by a production method described later. The cellulose dispersion, if suitable, has transparency comparable to that of a water-soluble polymer aqueous solution, and can be in a state where cellulose is highly dispersed in a dispersion medium. This makes it possible to provide a suitable ink composition. The average degree of polymerization of the cellulose to be used as an essential component in the compositions of the present invention (DP), the fraction of cellulose I and cellulose II type crystal component (chi _I and chi _II), the average particle diameter was calculated by the following procedure.

[0010] Fraction of cellulose type I crystal component (χ _I )
Is obtained by pulverizing a dried cellulose sample obtained by drying a cellulose dispersion into a powder, forming a tablet, and obtaining (110) of the cellulose type I crystal in a wide-angle X-ray diffraction diagram obtained by a reflection method using a radiation source CuKα. From the absolute peak intensity h _{0 at} 2θ = 15.0 ° attributed to the plane peak and the peak intensity h ₁ from the baseline at this plane interval, a value determined by the following equation (1) was used. Similarly, the fraction (χ _II ) of the cellulose type II crystal component can be determined by pulverizing a dried cellulose sample into a tablet and forming the tablet into a tablet. Crystal (11
0) From the absolute peak intensity h ₀ * at 2θ = 12.6 ° attributed to the plane peak and the peak intensity h ₁ * from the baseline at this plane interval, a value determined by the following equation (2) was used.

Χ _I = h ₁ / h ₀
(1) χ _II = h ₁ * / h ₀ * (2) FIG. 1 is a schematic diagram for determining χ _I and χ _II . In addition,
The cellulose sample was dried by a method such as a reduced pressure drying method to obtain a dried cellulose sample.

The average degree of polymerization (DP) specified in the present invention is:
The specific viscosity of a dilute cellulose solution obtained by dissolving the above dried cellulose sample in cadoxene was measured with an Ubbelohde viscometer (25 ° C.), and the intrinsic viscosity [η] was calculated by the following viscosity formula (3) and conversion formula (4). The calculated value was adopted. [Η] = 3.85 × 10 ⁻² × Mw 0.76 (3) DP = Mw / 162 (4) The average particle diameter of the cellulose constituting the present invention is determined by a laser diffraction particle size distribution analyzer (Horiba Co., Ltd.) It is an average particle diameter determined by measuring with a laser diffraction / scattering type particle size distribution analyzer LA-920, manufactured by Seisakusho, and the lower limit detection value is 0.02 μm). In order to measure the particle diameter in a state where the association between the particles in the dispersion medium was cut as much as possible, a sample was prepared in the following step.

After diluting the dispersion with water so that the cellulose concentration becomes about 0.5% by weight, the rotation speed is 15,000 rpm.
The mixture is mixed for 10 minutes with a blender having a capacity of at least m to produce a uniform suspension. Next, an aqueous dispersion sample obtained by subjecting this suspension to ultrasonic treatment for 30 minutes was supplied to a cell of a particle size distribution measuring device, and subjected to ultrasonic treatment again (3 minutes), and then the particle size distribution was measured. . In the present invention, the average degree of polymerization (D
P) is 100 or less, the fraction of the cellulose type I crystal component is 0.1 or less, the fraction of the cellulose type II crystal component is 0.4 or less, and the average particle diameter of the constituting cellulose is 5 μm It is characterized by using cellulose having the following low polymerization degree and low crystallinity.

In the present invention, the cellulose in the cellulose dispersion has an average degree of polymerization (DP) of 100 or less, preferably 50 or less. When the DP exceeds 100, it is difficult to obtain a cellulose dispersion highly dispersed in a dispersion medium. The cellulose of the present invention is a dispersion of water-insoluble cellulose, and has a DP of 20 or more. The cellulose of the present invention are cellulose I type crystal component amount (chi _I) is 0.
1 or less, preferably 0.06 or less, and cellulose II
The type crystal component amount (χ _II ) is 0.4 or less, preferably 0.3
The following low crystallinity is required. Fraction of cellulose crystalline component of the present invention can be up to (χc, i.e. the sum of the chi _I and chi _II) is a value close to almost zero. chi cellulose _I is more than or exceeds chi _II 0.4 0.1, because the interaction forces between the cellulose particles in the dispersion medium is lowered, and at the same time the function of the viscosity expression is extremely lowered, it The function of the compounded ink as a stabilizer is significantly reduced.

[0015] In addition, χ _I is more than 0.1, or χ
Cellulose having an _II of more than 0.4 decreases the transparency of the dispersion, and therefore reduces the sharpness when using the ink provided by using the cellulose. Furthermore, in the present invention, the average particle diameter of the cellulose constituting the cellulose dispersion is 5 μm or less, preferably 3.5 μm or less, more preferably 1 μm or less, according to the above-mentioned measurement method. The lower limit of the average particle size can be about 0.02 μm, which is close to the lower limit of detection of the measurement method defined by the present invention.
If the thickness exceeds 5 μm, functions such as the development of viscosity and the stabilization of the ink are extremely reduced, and the uniformity of the ink is lost.

The average particle diameter of the cellulose constituting the present invention is defined as the average particle diameter of the cellulose dispersion according to the present invention. Means the size of the "spread (diameter)" of the cellulose when it is dispersed as finely as possible by means of ultrasonic waves or the like according to the measurement method described above. The necessity of such handling depends on the form in which the cellulose of the present invention is present in the dispersion medium and the existing microcrystalline cellulose (MC
This shows that the form in which cellulose fine particles such as C) and microfibrillated cellulose (MFC) are present in the suspension is clearly different.

The cellulose in the cellulose dispersion of the present invention is different from the existing cellulose additives such as MCC and the like in that the particles are so highly dispersed in the dispersion medium that the particles cannot be clearly confirmed by observation with an optical microscope. Having.
Further, the cellulose of the present invention has a diameter of about 0.01 μm (1
(0 nm). Cellulose contained in the dispersion of the present invention, such fine structures are innumerably entangled to form a network-like structure, and are associated with a certain finite size and exist as a microgel. It is estimated to be.

The cellulose in the dispersion medium of the present invention has a very high associative property, and the extent of “spreading” varies depending on the degree of cutting of the associated state. For example, the average particle diameter of the dispersion of the present invention is a sample that has been left standing for a long time,
When measured without performing ultrasonic treatment, it may be measured to about several hundred μm, whereas when the same dispersion is measured by the average particle diameter measurement method defined in the present invention, the average particle diameter is It is measured to 5 μm or less. This is evidence that cellulose having a small particle size is extremely highly associated in the composition of the present invention. In the dispersion liquid of MCC or microfibrillated cellulose (MFC), the change of the average particle diameter as exemplified above is not usually observed.

In the aqueous recording liquid of the present invention, various constituent components are uniformly and stably dispersed, and the viscosity is stably maintained against various changes in temperature environment. The fact that the cellulose dispersion used in the present invention has excellent effects of thickening, dispersion stability, water retention, transparency and the like that cannot be achieved by conventional micronized cellulose is applied to the ink. This is presumed to be a factor that can exhibit high and stable dispersion in which excellent ink characteristics are exhibited. Further, since the cellulose dispersion used in the present invention has high water retention, it also has an effect of preventing drying of an aqueous recording liquid containing the same. This prevents evaporation of water, which is the main solvent of the recording liquid, and contributes to preventing nozzle clogging. Further, it is effective because the affinity with water as a solvent is increased and the redispersibility is improved. The term "redispersion" as used herein means that when water evaporates and dries, when the ink is supplied thereafter, the dried matter re-dissolves or re-disperses with the water, and solidified components such as colorants Mean that they are dispersed as before. Furthermore, when recording on paper using the aqueous recording liquid of the present invention, since the recording liquid contains cellulose, which is the same component as paper, extremely excellent fixability is exhibited.

The aqueous recording liquid of the present invention comprises the above-mentioned cellulose in an amount of 0.05 to 5% by weight based on the total weight of the aqueous recording liquid.
It is desired to contain. Within this range, an aqueous recording liquid having a uniform property can be suitably provided. Preferably 0.1 to 2% by weight, more preferably 0.2 to 1.5%
When the amount is within the range of 5% by weight, the aqueous recording liquid exhibits an appropriate viscosity. However, the viscosity and the like greatly depend on the contents of the constituent components. The appropriate composition may be determined according to the conditions. The recording liquid containing the cellulose of the present invention in excess of the upper limit of the concentration range of 5% by weight has a problem that the viscosity becomes too high to perform an optimal ejection, and the re-dissolving property is poor and clogging occurs. Will happen. When a cellulose dispersion below the lower limit of the range is used, the fixability of the pigment particles and the dye is reduced, and the desired performance improvement cannot be obtained, and at the same time, the function of adjusting the viscosity is significantly reduced.

In the present invention, when a pigment is used as a coloring agent, the cellulose also acts as a binder for the pigment on a recording material, thereby improving the water resistance and scratch resistance of the printed matter. In this case, when the value is below the lower limit, the water resistance and abrasion resistance of the printed matter are significantly reduced. By controlling the concentration of the aqueous recording liquid of the present invention within the above-mentioned range of the cellulose concentration, thixotropic properties can be imparted. For example, when used as an inkjet ink, the printing layer printed stepwise becomes extremely high in viscosity immediately after ejection due to thixotropy, so the colorants contained in each printing layer mutually diffuse. Can be prevented from mixing. Further, in the present invention, due to the high transparency of the cellulose dispersion used as an additive, compared with the case where a conventional cellulose additive is added, the aqueous recording liquid using the same has a uniform fine particle. Dispersibility and sharpness of the printed surface can be maintained.

According to the present invention, a uniform composition suitable as an aqueous recording liquid can be provided. The term "homogeneous state" as used herein means that after preparing an aqueous recording liquid by various mixing treatments,
When this is allowed to stand at 20 ° C. for 24 hours, it means a state in which separation and sedimentation of the components or aggregation of the components does not occur at all. Here, the separation and the sedimentation can be visually confirmed with respect to the recording liquid after standing. The presence or absence of aggregation is visually determined in a state where a part of the recording liquid is collected on a transparent glass plate and spread out. At this time, the separation of the components is observed, and those in a non-uniform state are determined to be agglomerated. For example,
In certain dispersion compositions, after a certain period of time after the mixing treatment, at first glance, it is observed that neither separation nor sedimentation has occurred. In some cases, non-uniform properties may occur. Such an aqueous recording liquid does not include the coloring agent such as a pigment, and cannot function as an intended aqueous recording liquid such that the dispersion state does not change for a long time, and thus is not included in the present invention. .

Usually, nonionic or ionic organic additives are used as additives in the aqueous recording liquid for the purpose of stabilizing various colorants. The ionic additive stabilizes the pigment particles using a polymer such as a neutralized acrylic, maleic or ion-containing monomer such as vinyl sulfonic acid. These polymers are charged electricity 2
The formation of an overlay stabilizes the system, and the ionic repulsion by this mechanism prevents particle aggregation. In contrast, cellulose used as an additive in the present invention is considered to act as a nonionic additive. In other words, since many molecular groups are contained in the molecular chain skeleton, various components such as colorants have strong interactions through hydrogen bonding and, in some cases, Van der Waals forces. It is considered that by forming a layer to form a kind of protective colloid, the system is stabilized without causing aggregation. By this effect, a high degree of dispersion stability of various components having not only hydrophilic properties but also hydrophobic properties is achieved. Considering that various hydrophobic functional agents are often added in order to enhance the product properties of the dispersion composition, the cellulose used in the present invention, which is rich in amphiphilicity, can be applied in a wide range of composition. Is extremely effective. In the aqueous recording liquid containing cellulose of the present invention, the dispersibility or dissolution stability of the colorant is increased, and the long-term storage stability, which is one of the objects of the present invention, is improved.

Further, since the cellulose dispersion used as a raw material in the present invention can be dispersed in a wide pH range, it exhibits excellent pigment dispersion stability that can be used in a wide pH range. In particular, a suitable aqueous recording liquid having a pH in the range of 3 to 11 can be provided. For example, slightly acidic (pH
= 3-4), when a pigment such as carbon black is used as a colorant, a very ideal recording liquid can be provided by this property of the cellulose dispersion used in the present invention.

Further, the cellulose dispersion used in the present invention has a property that the temperature change of the rheological properties is small, and probably due to this property, the aqueous recording liquid of the present invention can be used at a normal use temperature. In a temperature range from a certain room temperature to 100 ° C., the change in viscosity is extremely small. This property is extremely effective when a thermal energy is applied to the ink jet recording method because it can prevent the viscosity of the recording liquid from decreasing due to the temperature rise.

The pigment as a coloring agent that can be used in the present invention is not particularly limited, and any pigment having a good affinity for water as a main solvent can be used. For example, colorants for black and white include carbon blacks such as furnace black, lamp black, acetylene black, and channel black; metals such as copper, iron, and titanium oxide; and organic pigments such as aniline black. Further, for color, phthalocyanine-based, anthraquinone-based, dioxazine-based, quinacridone-based, quinacridone-quinone-based, anthrapyrimidine-based, ancesthrone-based, indanthrone-based, flavanthrone-based, perylene-based, perinone-based, diketopyrrolopyrrole-based And quinophthalone-based, indigo-based, thioindigo-based, isoindolinone-based, isoindoline-based, benzimidazolone-based, azo-based pigments, lake pigments, and other processed pigments such as graft carbon whose pigment surface is treated with a resin or the like.

As for the dye, all dyes such as a direct dye, an acid dye, an edible dye, a basic dye, a fluorescent dye and the like which are conventionally known can be used. For example, as direct dyes, benzidine type, stilbene type, polyazo type, etc., as acidic dyes, azo type, anthraquinone type, triphenylmethane type, xanthene type, etc., as food dyes, monoazo type, xanthene type, Triphenylmethane type, indigo type and the like, and basic dyes include trial methane type, methine type, azo type, azamethine type, anthraquinone type, azine type, diarylmethane type, xanthene type and thiazine type. The coloring agents can be used alone or in combination of two or more.

The amount of the coloring agent varies depending on the purpose, but is 0.5 to 30% by weight based on the total weight of the aqueous recording liquid.
And preferably 2 to 12% by weight to provide a more suitable aqueous recording liquid. When stored for more than 30% by weight for a long period of time, dyes are precipitated and pigments are liable to agglomerate. If the content is less than 0.5% by weight, the coloring becomes weak, and the hue when writing on paper becomes unclear. In particular, when a pigment is used as a coloring agent, the particle size is 25%.
It is preferable to use a pigment having a particle size of 1 μm or less.
It is preferable to use a pigment having the following particle size.

Conventionally, ink solvents such as water, which is the main solvent, have been used because of their low viscosity, excellent safety, easy handling, low cost, and no odor. And an aqueous medium composed of a water-miscible organic solvent. In the present invention, such an aqueous medium is used as a solvent. That is, the aqueous medium of the present invention means water or a mixed solution of water and at least one water-miscible organic solvent. Examples of the water-miscible organic solvent include amides such as dimethylformamide and dimethylacetamide, ketones such as acetone, ethers such as tetrahydrofuran and dioxane, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, and ethylene glycol. Alkylene glycols such as propylene glycol, diethylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, etc. Lower alkyl ethers of polyhydric alcohols, ethanol,
In addition to alcohols such as isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, and glycerin,
Esterified products of these series of alcoholic compounds, and further N-methyl-2-pyrrolidone, 1,3-dimethyl-
Examples include, but are not limited to, imidazolidinone, triethanolamine, sulfolane, dimethyl sulfoxide, and the like.

The content of the water-miscible organic solvent is not particularly limited. However, considering the advantages of the aqueous ink described above, printing bleeding occurs at 50% by weight or less based on the total weight of the aqueous recording liquid. It is preferable to add it in a range that does not exist. 5
If the content exceeds 0% by weight, advantages of the aqueous recording liquid such as safety, cost and odor are lost. These water-miscible organic compounds are used to prevent clogging of the ejection nozzles and to provide quick-drying properties, water resistance of printed matter, abrasion resistance,
It contributes to various ink characteristics such as improvement of long-term storage stability. More specifically, for example, a highly volatile monohydric alcohol such as ethanol, isopropanol, or isobutanol, or hexanol is used for the purpose of improving the drying property, the fixing property, and the wettability of the ink jet head and the ink supply channel. A water-miscible organic solvent having excellent water solubility, such as relatively low-volatility alcohols such as heptanol and octanol, can be mixed with water and used as an ink medium.

Further, a known hydrophilic polymer or a surfactant may be added in order to further improve fixability on a recording material, water resistance, and film formability. Examples of hydrophilic polymers include proteins such as gelatin and albumin, natural gums such as gum arabic and tragacanth, glucosides such as saponin, cellulose derivatives such as methylcellulose, carboxycellulose and hydroxymethylcellulose, ligninsulfonates and shellac. Natural polymers,
Polyacrylate, styrene-acrylic acid copolymer salt, vinyl naphthalene-acrylic acid copolymer salt, styrene-maleic acid copolymer salt, vinyl naphthalene-maleic acid copolymer salt, β-naphthalene Salts of sulfonic acid formalin condensates, anionic polymers such as phosphates, polyvinyl alcohol, polyvinylpyrrolidone, nonionic polymers such as polyethylene glycol, alkylolamine salt polymers of polyfunctional polymers having anionic and nonionic properties, Other polymeric additives such as high molecular weight copolymers, surfactants include fatty acid salts, higher alcohol sulfates, liquid fatty oil sulfates, anionic surfactants such as alkyl allyl sulfonates, polyoxyethylene Alkyl ethers, polyoxyethylene alkyl esters, Sorbitan alkyl esters, there are nonionic surface active agents such as polyoxyethylene sorbitan alkyl esters, can be used to select these one or more appropriate. The amount used depends on the type of the additive, but is generally desirably in the range of 0.01 to 20% by weight based on the total weight of the aqueous recording liquid.

If necessary, pH adjusters such as organic amine, ammonia, potassium dihydrogen phosphate and sodium dihydrogen phosphate, and benzoic acid, dichlorophen, hexachlorophen, sorbic acid, paraben for the purpose of fungicide and rust prevention. Hydroxybenzoic acid esters, ethylenediaminetetraacetic acid, benzotriazole, and the like can be included. Further, in order to improve the physical properties of the recording liquid, a nonionic surfactant, an ionic surfactant, a surfactant and the like can be contained.

One preferred example of the preparation of the aqueous recording liquid of the present invention is described below. Cellulose is dissolved in a mineral acid (for example, an aqueous sulfuric acid solution) capable of dissolving cellulose in an amount of 50% by weight or more, and an acid dispersion of a cellulose aggregate obtained by reprecipitating such a solution in water is heated. 50-1
The hydrolysis treatment is performed in a temperature range of 00 ° C. The reaction time varies depending on the temperature, but is desirably in the range of about 5 minutes to 180 minutes. The dispersion obtained by this step is filtered,
Purify by repeating washing with water. During this time, neutralization may be performed with an alkaline aqueous solution such as dilute ammonia water. However, in this case, it is preferable to further wash with water after the neutralization to wash out the neutralized salt generated by the neutralization.

The thus obtained gel having a pH value of 2 or more, preferably 4 or more, as it is, or after mixing or substituting with an organic solvent such as ethanol, and then subjecting to a micronization treatment, gives an aqueous dispersion of cellulose. Alternatively, a dispersion in an organic solvent is prepared. At this time, application of an ultrahigh-pressure homogenizer, a bead mill, an ultrasonic treatment, or the like is effective as the fine processing. The final fine processing may be performed a plurality of times as necessary. Natural cellulose such as wood pulp or cotton can be suitably used as the starting cellulose, but regenerated cellulose may be used.

Next, various blends are appropriately added to the dispersion of cellulose particles thus obtained, and the mixture is subjected to a mixing treatment according to the purpose to produce an aqueous recording liquid. For example, a colorant and a dispersion of cellulose particles and, if necessary, other additives are premixed in an aqueous medium, and then the colorant is dissolved, dispersed or deagglomerated. Specifically, a dispersion treatment such as mixing, stirring, and kneading is performed. For example, at least 5,0 is passed through a plurality of nozzles in a horizontal small mill, a ball mill, or an attritor.
By passing the liquid through the liquid jet interaction chamber at a liquid pressure of 00 psi, a recording liquid for writing in which the coloring material is uniformly dispersed in the aqueous medium can be produced.

[0036]

EXAMPLES The present invention will be described in more detail with reference to examples and the like. In the following Examples and Comparative Examples, the average particle size, the fraction of the crystal component, and the average degree of polymerization (DP) were measured by the above-described measuring methods. (Preparation Example 1) An example of preparing an aqueous dispersion of cellulose which is an essential raw material of the composition of the present invention will be described. Sulfite pulp sheet (DP = 76) cut into chips of 5 mm × 5 mm
0) was uniformly dissolved in a 65% by weight aqueous sulfuric acid solution at −5 ° C. so that the cellulose concentration was 6% by weight, to obtain a cellulose dope. The cellulose dope was poured into 2.5 times by weight of water (5 ° C.) while stirring, and the cellulose was precipitated and aggregated in flocs to obtain a suspension (15 ° C.).

The suspension was hydrolyzed at 85 ° C. for 60 minutes, and then sufficiently washed with water and dehydrated under reduced pressure until the pH became 4 or more, and a white, transparent cellulose solution having a cellulose concentration of 6.5% by weight was obtained. A paste-like gel was obtained. The gel was diluted with ion-exchanged water to a cellulose concentration of 4.0% by weight, and mixed with a blender at a rotation speed of 10,000 rpm for 5 minutes. The diluted sample is subjected to an ultra-high pressure homogenizer (Microfluidizer M-110EH).
Mold, manufactured by Mizuho Industry Co., Ltd., operating pressure 1750 kg / cm
^The mixture was treated four times in ² ) to obtain a highly transparent cellulose dispersion (sample J1). Cellulose J1 sample, DP is 32, chi _I is 0.0, chi _II 0.31, average particle diameter was 0.28 .mu.m.

(Preparation Example 2) Commercially available microcrystalline cellulose (M
CC), a 1% by weight aqueous dispersion was prepared using an aqueous dispersion (H1 sample; cellulose concentration 10% by weight, average particle diameter 5 μm). Adjustment of the dispersion sample after dilution with ion exchange water,
This was performed by mixing at a rotation speed of 10,000 rpm for 3 minutes in a blender, and a white cellulose dispersion (H2
Sample). The cellulose of the H2 sample had a DP of 20.
0, χ _I is 0.65, χ _II was 0. The transparency of the dried coating film of the cellulose dispersion is considered to be a factor affecting the sharpness of the printed surface when using the aqueous recording liquid obtained by blending the cellulose dispersion. The transparency of the coatings obtained from the pure cellulose suspension was compared.

[0039]

Example 1, Comparative Example 1 J1 obtained in Preparation Example 1 was diluted with ion-exchanged water and blended (10000 rpm × 3).
) And the H2 sample was cast on a glass plate (slide glass). After heating and drying at 60 ° C. for 1 hour, the thickness of each coating film was about 8 μm, but the cellulose coating film was completely transparent in J1 and white and opaque in H2. The results of casting by J1 and H2 are referred to as Example 1 and Comparative Example 1, respectively. Thus, the cellulose dispersion (J
Since 1) has high transparency, it was suggested that, when this is used for an aqueous recording liquid, the problem that the sharpness of a printed surface is impaired when a conventional cellulose dispersion is used can be solved.

[0040]

Examples 2 to 3 and Comparative Examples 2 to 5 A pigment-dispersed aqueous recording liquid and a dye-dissolved aqueous recording liquid having the following compositions were prepared, and their properties as inks were evaluated. 90. Example 2 CB (RCF45L, carbon black manufactured by Mitsubishi Chemical Corporation); 7% by weight cellulose (supplied as cellulose dispersion J1 in Preparation Example 1); 0.5% by weight n-butanol; 2% by weight water; 5% by weight Total 100

Example 3 Acid dye (Red No. 104); 5% by weight cellulose (supplied as cellulose dispersion J1 in Preparation Example 1); 0.5% by weight n-butanol; 2% by weight water; 92.5% by weight Total 100 Comparative Examples 2 CB (RCF45L, carbon black manufactured by Mitsubishi Chemical Corporation); 7% by weight hydroxyethylcellulose; 0.5% by weight (manufactured by Tokyo Chemical Industry Co., Ltd., 4000-6500 cps (2% by weight in water at 25 ° C.)) n-butanol; 2% by weight water; 90.5% by weight total 100

Comparative Example 3 Acid dye (Red No. 104); 5% by weight hydroxyethyl cellulose; 0.5% by weight (Tokyo Kasei Co., Ltd., 4000-6500 cps (2% by weight in water at 25 ° C.)) n-butanol; 92.5 wt% Total 100 Comparative Example 4 CB (RCF45L, carbon black manufactured by Mitsubishi Chemical Corporation); 7 wt% Cellulose (supplied as cellulose dispersion H1 in Preparation Example 2); 0.5 wt% n-butanol; 2% by weight water; 90.5% by weight total 100

Comparative Example 5 Acid dye (Red No. 104); 5% by weight cellulose (supplied as cellulose dispersion H1 in Preparation Example 2); 0.5% by weight n-butanol; 2% by weight water; 92.5% by weight Total 100

The aqueous recording liquid was prepared by adding 200 parts of 0.3 mmφ zircon beads to a mixture prepared by preparing predetermined components for both of the two types (pigment-based and dye-based). The mixture was stirred and mixed with a paint conditioner for 30 minutes or more, and it was confirmed by microscopic observation that the particle size of the compounded components was about 1 μm or less. Thereafter, the dispersion was subjected to pressure filtration with a 5 μm filter to remove dust and coarse particles. It was done by doing. The viscosity of the obtained recording liquid was evaluated by measuring the viscosity of the dispersion at 25 ° C. with an E-type viscometer manufactured by Tokimec Co., Ltd.

The recording liquids of Examples 2 and 3 and Comparative Examples 2, 3, 4, and 5 thus obtained were put into a cartridge of an ink jet printer (“Inkjet Printer MJ-510C” manufactured by Seiko Epson Corporation) and recording was performed. The print evaluation was performed by evaluating the print quality by observing the print sample with a microscope (comprehensive evaluation of the sharpness and bleeding property of the print), leaving the solid print for 2 hours and then rubbing strongly with a finger. The ink was evaluated for water resistance to evaluate the degree of fading after immersion for one minute, and discharge stability for investigating the state of dot omission in printing after standing at 40 ° C. for 2 days.

The uniformity of the ink is determined by preparing an aqueous recording liquid by various kinds of mixing treatments, and then allowing the mixture to stand at 20 ° C. for 24 hours to visually check the presence or absence of separation or settling of the components or aggregation of the components. It was determined by The presence or absence of aggregation was visually confirmed in a state where a part of the recording liquid was collected on a transparent glass plate and spread out. In addition, at an ambient temperature of 50 ° C. in a closed glass sample bottle,
After leaving for 4 days, the storage stability was evaluated by examining the degree of aggregation of the coloring material in the ink kept at room temperature.

The symbols in the table are based on each evaluation result.
：: excellent, no problem, Δ: slightly problematic, ×: poor,
The results of a three-stage subjective evaluation of clearly having a problem are shown.
The evaluation of the fixing property was determined based on the time until the image flow did not occur even after rubbing with a finger after printing on the recording paper. A sample having a fixing property of less than 20 seconds was rated as ○, a sample having a fixing property of 20 seconds or more and less than 40 seconds was rated as Δ, and a sample having a fixing property of 40 seconds or more was rated as ×. Table 1 shows the above results.

The aqueous recording liquid of the present invention is uniform, has high print quality without bleeding in all the evaluations performed this time, has sufficient water resistance, abrasion resistance, fixability, and has a fine There was no clogging of the discharge nozzle, and the discharge stability was good. Further, even when the recording liquid was stored at a high temperature for a long period of time, there was no aggregation or sedimentation of the pigment particles, and no solid content was precipitated. Therefore, all the characteristics required for ink jet recording could be satisfied. On the other hand, Comparative Examples 2, 3, 4, 5
With the recording liquid of No. 4, it was not possible to achieve both uniformity, print quality, ejection stability, water resistance, abrasion resistance, long-term storage stability, and fixability.

[0049]

[Table 1]

Although the embodiments of the present invention have been described in detail above, the recording liquid of the present invention is not limited to these configurations, materials, and manufacturing methods. According to the recording liquid of the present invention, high print quality, clogging resistance, water resistance of printed matter, abrasion resistance,
Because of its excellent fixability, it can be used for a page printer, a color printer, or a high-speed page printer using a line head. Furthermore, general printing inks and ballpoint pens that require similar properties and physical properties,
It can also be used as a recording liquid for marking pens, fountain pens and the like.

[0051]

An aqueous medium, a coloring agent such as a dye or a pigment,
And an aqueous recording liquid comprising various aqueous additives,
As an aqueous additive, the average degree of polymerization (DP) is 100 or less, the fraction of the cellulose type I crystal component is 0.1 or less, the fraction of the cellulose type II crystal component is 0.4 or less, and the constituent cellulose By using cellulose having an average particle diameter of 5 μm or less, the aqueous recording liquid can stably maintain appropriate viscosity and uniformity in a wide range of temperature environments, and can be fixed to paper or the like. It is possible to provide an excellent recording liquid.

[Brief description of the drawings]

[1] Cellulose I-type crystal fraction chi _I and cellulose I
It is a schematic diagram showing how to determine the I-type crystal fraction chi _II.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Naoji Sawada 1-1-2 Yurakucho, Chiyoda-ku, Tokyo Asahi Kasei Kogyo Co., Ltd. (72) Inventor Yuji Matsue 6-4100 Asahicho, Nobeoka-shi, Miyazaki Asahi Kasei Kogyo Incorporated F term (reference) 2C056 EA26 FC01 2H086 BA53 BA55 BA59 BA60 BA62 4J039 AB02 BE01 BE02 BE06 GA24 GA28

Claims (4)

[Claims] 1. An aqueous recording liquid comprising a dye or a pigment and an aqueous medium in which the dye or pigment is dissolved or dispersed as a main component, and mixed with an aqueous additive, has an average degree of polymerization (DP) of 100 as an aqueous additive. Below, the fraction of the cellulose type I crystal component is 0.1 or less, the fraction of the cellulose type II crystal component is 0.4 or less, and the average particle diameter of the constituting cellulose particles is 5 μm or less. Aqueous recording liquid characterized by the following: 2. The aqueous additive cellulose is added to 0.05%.
The aqueous recording liquid according to claim 1, wherein the aqueous recording liquid is contained in an amount of from 5 to 5% by weight. 3. The aqueous recording liquid according to claim 1, wherein the aqueous recording liquid is an ink for inkjet recording. 4. The aqueous recording liquid according to claim 1, wherein the aqueous recording liquid is an ink for a writing instrument.