JPH09272831A - Recording medium solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a recording medium solution excellent in dispersibility of colorant components and long-term storage stability and improved in concentration, clarity, water resistance and light resistance of a formed image. SOLUTION: This recording medium solution comprises a liquid medium useful in an ink jet recording method and a colorant component. A pigment composite polymer prepared by heating a polymer having (A) a segment containing a reactive group to be reacted with a functional group on the surface of a pigment and (B) a segment substantially not containing a reactive group and having affinity for the liquid medium than that of the segment A and a pigment is contained as the colorant component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium liquid used in an inkjet recording method. More specifically, it relates to a recording medium liquid containing as a colorant component a pigment composite polymer obtained by treating a pigment with a block or graft type polymer.

[0002]

2. Description of the Related Art An ink jet recording method is one in which a recording medium liquid, which is so-called ink, is ejected as a stream of droplets and adhered to a recording member for recording. As the inkjet recording method, various methods have been proposed and put into practical use depending on the generation and control methods of droplets of a recording medium liquid. For example, as a method of generating droplets, a part of the wall surface of the ink chamber is composed of a piezoelectric element (piezo element), a recording signal is applied to the piezoelectric element to press the ink, and droplets are generated according to the signal. A typical one that has been put into practical use is a piezoelectric pressurization method that applies heat energy corresponding to a recording signal to the recording liquid in the ink chamber to generate bubbles in the ink and generate droplets by the pressure. In addition, a method of ejecting ink from a nozzle at a relatively high pressure to make particles by surface tension and electrification during flight, a method of ejecting ink at a relatively low pressure to superimpose ultrasonic vibration, and a meniscus A method of sucking spherical ink with a high electric field is known.

The ink used in the ink jet recording method, that is, the recording medium liquid, is suitable for the ejection conditions (for example, the driving voltage of the piezoelectric element, the driving frequency, the shape and material of the ejection orifice, the diameter of the ejection orifice, etc.). It has liquid physical properties (viscosity, surface tension, electrical conductivity, etc.), is stable for long-term storage, does not cause clogging of inkjet devices, and can be fixed to recording materials (paper, film, etc.) It is fast and reliable, and the area around the dots is smooth and has little bleeding, the color tone of the formed ink image is clear and the density is high, and the formed ink image has excellent water resistance and light resistance. That it is not corrosive to ink peripheral materials (container, connecting tube, sealant, etc.), has little air collection and toxicity, and is highly safe such as flammability, etc. It is desired with various characteristics.

Conventionally, as a recording medium liquid used in the ink jet recording method, a liquid mainly composed of a dye as a colorant component and its solvent has been mainly used. For this reason, the physical properties of the recording medium liquid largely depend on the properties peculiar to the dye used, and for example, when ink jet recording is performed using a recording medium liquid containing a water-soluble dye, the obtained ink image is There is a drawback in that the water resistance and the light resistance are inferior depending on the physical properties of the water-soluble dye. In addition, the storage stability of the ink itself containing such a water-soluble dye was not sufficient.

Therefore, instead of such a dye-based ink, an attempt has been made to apply a pigment-based ink using a pigment such as carbon black as a colorant component to an ink jet recording method. This pigment-based ink has an advantage that the light resistance and water resistance of the obtained ink image are extremely good as compared with the image by the dye-based ink. However, on the other hand, since the pigment is insoluble in the liquid medium of the ink, it requires a high technique to finely disperse the pigment in the liquid medium of the ink, and it is very difficult to enhance the dispersion stability. .

By the way, carbon black has a coloring property,
Since it has excellent weather resistance and chemical resistance, it is widely used for various purposes such as a coloring agent, a reinforcing agent for plastics or elastomers, and a filler. However, since the shape of carbon black is powdery or granular, it is rarely used alone and is usually uniformly dispersed in a solid base material such as rubber or resin or a liquid such as water or a solvent. Exert its characteristics. However, carbon black has a weak affinity for other substances, such as organic polymers, water, and organic solvents, as compared with the cohesive force between particles, so under normal mixing or dispersing conditions, uniform mixing or dispersion is achieved. It was extremely difficult to do.

In order to solve this problem, the surface of carbon black is coated with various surfactants or resins to improve the dispersibility of carbon black by increasing the affinity with a solid or liquid substrate. There are many studies to be done.

The carbon black graft polymer obtained by polymerizing a polymerizable monomer in the coexistence of carbon black has an appropriate hydrophilicity and / or lipophilicity by appropriately selecting the type of the polymerizable monomer. It can be changed (for example, Japanese Patent Publication 42-
22047, JP-B-44-3826, JP-B-45-
17248, JP-B-46-26970). However, the yield of the carbon black graft polymer obtained by these methods is as low as several% to several tens%, most of them are present in the form of vinyl homopolymer, and the surface treatment efficiency of carbon black is extremely low. . Therefore, the affinity with other substances was not improved as expected, and the dispersion state was often different depending on the mixing or dispersion conditions.

In order to solve this problem, a carbon black graft polymer obtained by reacting a polymer having a reactive group such as an epoxy group or an aziridine group in the molecule with carbon black has been proposed (Japanese Patent Publication No. 2-2
No. 4868, Japanese Patent Publication No. 6-27269), and the carbon black graft polymer had improved dispersibility in various substances.

However, this carbon black graft polymer is one in which the polymer has a functional group reactive with carbon black, but the polymer chain has only lipophilic or hydrophilic characteristics. Therefore, it is possible to sufficiently satisfy both contradictory requirements in many cases in terms of grafting efficiency with respect to carbon black and improvement of dispersibility in various target media to be imparted by the grafted polymer chain. It was difficult.

Therefore, it is not possible to increase the carbon content in the carbon black graft polymer, and a highly polar medium such as alcohol or cellosolve-based solvent,
Alternatively, there have been problems that sufficient dispersibility cannot be imparted to a medium having low polarity, such as a hydrocarbon solvent and a silicone solvent, and that grafting in an organic solvent is difficult.

It is possible to use such a carbon black graft polymer as a colorant component of a recording medium liquid used in the bubble jet recording method as described above, but in that case, due to the above-mentioned problems, The carbon black content cannot be increased, and the color tone of the ink image cannot be sufficiently vivid and high density,
There are problems that it is difficult to set the conductivity suitable for the discharge conditions, the stable dispersion state cannot be maintained, and the long-term storage stability is insufficient.

[0013]

Therefore, an object of the present invention is to provide a novel recording medium liquid.

Another object of the present invention is that the dispersibility of the colorant component and the long-term storage stability are excellent, and the density, sharpness,
It is to provide a recording medium liquid having excellent water resistance and light resistance.

[0015]

The above objects are achieved by the following (1) to (11).

(1) A recording medium liquid containing a liquid medium used in an ink jet recording method and a colorant component, the segment having a reactive group capable of reacting with a functional group on the pigment surface as the colorant component. A polymer having (A) and a segment (B) having substantially no reactive group and having a higher affinity for a liquid medium than the segment (A) is obtained by heating with a pigment. A recording medium liquid containing a pigment composite polymer as described above.

(2) The recording medium liquid as described in (1) above, wherein the pigment is carbon black.

(3) The reactive group contained in the segment (A) is at least one or two or more selected from the group consisting of epoxy group, thioepoxy group, aziridine group, N-hydroxyacrylamide group and oxazoline group. The recording medium liquid according to (1) or (2) above.

(4) The segment (A) is obtained by polymerizing a vinyl-based monomer composition containing a vinyl-based monomer having at least a reactive group, and contains a main chain having a carbon-carbon bond. The recording medium liquid according to any one of (1) to (3) above.

(5) The segment (A) is obtained by polymerizing a vinyl-based monomer composition containing a vinyl-based monomer having at least a reactive group, and a reactive group and an aromatic ring are contained in the polymer chain. The recording medium liquid according to any one of (1) to (4) above, which is contained.

(6) Polymerization of a vinyl-based monomer composition in which the segment (A) contains 50 mol% or more of a vinyl-based monomer having an aromatic ring and a vinyl-based monomer having a reactive group. The recording medium liquid according to any one of (1) to (5) above, which is obtained by.

(7) The segment (B) is a polysiloxane structure, a poly (meth) acrylic structure, a polyether structure, a poly (meth) acrylonitrile structure, a polyester structure, a polyalkylene structure, a polyamide structure,
The recording medium liquid according to any one of (1) to (6) above, which has at least one selected from the group consisting of a polyimide structure and a polyurethane structure.

(8) The recording medium liquid according to any one of (2) to (7) above, wherein the average particle size of carbon black is in the range of 0.0005 to 0.4 μm.

(9) The recording medium liquid according to any one of (2) to (8), wherein 1 to 1000 parts by weight of the polymer is grafted to 100 parts by weight of the carbon black.

(10) The recording medium liquid according to any one of (2) to (9) above, wherein the carbon black has a carboxyl group.

(11) The above (2) to (1), wherein the carbon black is acidic carbon black having a pH of less than 7.
The recording medium liquid according to any one of 0).

[0027]

FUNCTION Carbon black, which is one of the typical pigments, usually has a particle size of several nm to several hundred nm. However, since carbon black has a large cohesive force between particles, it is usually handled as an aggregate having a particle size of several microns or more. In addition, the cohesive force between carbon blacks is significantly higher than the affinity between carbon blacks and other media, and it is very difficult to disperse carbon blacks in media in the submicron range. This is common to many other pigments.

On the other hand, in a pigment composite polymer obtained by compositing such a pigment with a polymer, for example, a carbon black graft polymer, the polymer portion effectively enters between the particles of the pigment and the cohesive force between the pigments is increased. Can be weakened. Furthermore, when the polymer moiety is compatible with the medium,
The pigment composite polymer can be submicron dispersed in the medium. However, even if the polymer portion has a high affinity with the medium, if the polymer portion is not effectively complexed or grafted to the pigment portion, its properties will not be stable and will vary. And the content of the pigment in the pigment composite polymer becomes low when an attempt is made to obtain a certain level of affinity, resulting in restrictions on the application.

As a result of intensive studies by the present inventors, the use of a polymer having a plurality of segments having different properties, such as a block type or a graft type, as a polymer forming a polymer portion makes it possible to more effectively form a composite. It has been found that it is possible to obtain a pigment composite polymer having excellent dispersibility in grafting and various medium liquids of recording medium liquid as compared with the conventional carbon black graft polymer and the like. That is, the polymer to be complexed with the pigment has a segment (B) having a high affinity for the medium liquid and a segment (A) having a lower affinity for the medium liquid than the segment (B), and From the medium liquid or a medium having properties (polarity) close to that of the medium liquid, the segment (A) is molecularly designed to have a reactive group that reacts with the surface functional group of the pigment and contributes to complexation or grafting. The pigment composite polymer obtained by heating the polymer and the pigment in the following dispersion medium liquid is used as the colorant component.

FIG. 1 shows that, as described above, carbon black is reacted with a block or graft type polymer having the above-described reactive group in a dispersion medium liquid comprising a medium liquid or a medium having properties close to this. It is a figure which shows typically the state in the vicinity of the carbon black surface at the time of making it. The polymer according to the present invention is composed of the segment (A) having a reactive group and the segment (B) having an affinity for the medium liquid as described above, and therefore, in the reaction system, as shown in the figure. In addition, since the segment (B) is oriented so as to have a shape that extends toward the dispersion medium liquid,
Since the segment (A) inevitably surrounds the surface of the carbon black particles and provides a suitable reaction field for grafting carbon black and this polymer, effective complexing or grafting is performed. is there.

In the carbon black graft polymer thus obtained, the graft chains bonded to the surface are oriented so that the segment (B) having a high affinity for the medium liquid is exposed to the outside, and therefore the graft chain is It has a high affinity and the carbon black graft polymer can be dispersed in the medium liquid in submicron units.

The carbon black graft polymer thus obtained has a polymer portion which is more effectively grafted and has a better dispersibility, so that it is better than the conventional carbon black graft polymer in the medium liquid. It can have excellent characteristics such as good and stable dispersion, a large carbon content in the carbon black graft polymer, a relaxation of the polymerization inhibition effect of the carbon black itself, and a high electric insulation. Will be things. Therefore, a recording medium liquid containing this carbon black graft polymer as a colorant component can make the color tone of an ink image sufficiently clear and have a high concentration, and should be set to an electrical conductivity that is preferably suited to ejection conditions. In addition, it is possible to stably maintain a good dispersed state of the colorant component, which is extremely excellent in terms of long-term storage stability. Further, as described above, in the carbon black graft polymer used in the recording medium liquid according to the present invention, the block-type or graft-type polymer chain as described above is firmly bound to carbon black through a covalent bond or the like. Therefore, for example, even when compared with a case where a recording medium liquid is prepared by adding a similar block-type or graft-type polymer and carbon black to the liquid medium in an unbonded state, Clearly, the improvement of the dispersibility of carbon black by the polymer chain is clearly exhibited.

A pigment composite polymer obtained by using a pigment other than carbon black as the pigment component and compounding the polymer component according to the present invention as described above is the same as the carbon black graft polymer according to the present invention. The recording medium liquid having excellent properties and containing the pigment composite polymer naturally exhibits the same excellent properties as described above.

The "pigment composite polymer" referred to in the present specification is obtained by heat-treating a pigment and a polymer having a reactive group having reactivity with a surface functional group of the pigment. That is, the polymer is stably attached to the surface of the primary particles of the pigment or several aggregates.
It is theoretically considered that the stable adhesion of the polymer to the surface of the pigment particle is due to some chemical bond between the surface of the pigment particle and the polymer, for example, grafting as described below. , Analytically showing whether such grafting occurs or not is not without some difficulty, and in practice, in many cases, not only such chemical bonding force but also physical adhesion force is Since it is probably acting, in the sense of including such a state,
It is defined as "composite polymer" or "composite".

The term "carbon black graft polymer" used herein refers to fine particles in which a polymer portion is grafted to a carbon black portion. The carbon black graft polymer is obtained by grafting a polymer on primary particles of carbon black or several aggregates. Furthermore, the term "grafting" used herein means carbon as defined by Jean-Baptiste Donnet et al. In its book "Carbon Black" (published by Kodansha Co., Ltd. on May 1, 1978). It is the irreversible addition of polymer to a substrate such as black.

By carrying out an irreversible addition reaction, the polymer portion can be chemically bonded to the surface portion of the carbon black particles, and thus the above both can be reliably bonded. Addition reactions that can be used for "grafting" include electrophilic addition reactions, radical addition reactions, nucleophilic addition reactions, and cycloaddition reactions.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail based on embodiments.

The pigment used for producing the pigment composite polymer according to the present invention is not particularly limited, and may be an organic pigment, an inorganic pigment, or a mixture thereof.

Examples of the inorganic pigments include alumina, titanium dioxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth and various inorganic pigments. Oxide pigments, chromium oxide, cerium oxide,
Powder or particles of red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, fine silica powder, silicon carbide, silicon nitride, boron carbide, tungsten carbide, titanium carbide, cerium oxide, carbon black, etc. Is mentioned. Further, such an inorganic pigment may have been treated with a known hydrophobizing agent such as a titanium coupling agent, a silane coupling agent, or a higher fatty acid metal salt.

Examples of organic pigments include Navels Yellow, Naphthol Yellow S, Hansers Yellow G, Hansers Yellow 10G, Benzidine Yellow G,
Yellow pigments such as Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, etc., Kilybdenum Orange, Permanent Orange R
Orange pigments such as K, benzidine orange G, indanthrene brilliant orange GK, permanent red 4
Red pigments such as R, Resole Red, Pyrazolone Red 4R, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eomine Lake, Rhodamine Lake B, Buzalin Lake, Brilliant Carmine B, and Purple Pigments such as Fast Violet B and Methyl Violet Lake, Alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partial chloride, blue pigments such as fast sky blue, indanthrene blue BC, pigment green B, malachite green lake, final yellow green G, etc. Examples include green pigments and the like.

In the following, the present invention will be described focusing on an embodiment in which carbon black is used as a pigment and a polymer is compounded with the carbon black to obtain a pigment composite polymer. Further, in order to make the understanding of the present invention easier, the pigment composite polymer obtained in the embodiment is expressed as “carbon black graft polymer” in the following. Not just what the coalesced "grafted",
It should be noted that, in a broader sense, the polymer may include "complexed", that is, carbon black composite polymers.

The carbon black used for producing the carbon black graft polymer according to the present invention is not particularly limited as long as it has a functional group such as a carboxyl group or a hydroxy group on the surface thereof. For example, furnace black, Any kind of channel black, acetylene black, lamp black and the like can be used, and ordinary commercial products can be used as they are, but those having a carboxyl group are preferable. Further, as the carbon black, it is preferable to use a carbon black having a pH of less than 7, particularly a pH of 1 to 5. Carbon black having a carboxyl group is easily available as acidic carbon black, but carbon black obtained by oxidizing neutral or basic carbon black can also be suitably used as a raw material in the present invention. If the carbon black does not have a functional group such as a carboxyl group or has a pH of 7 or higher, grafting may not be effectively performed. The carbon black pH test method is according to JIS K 6211.

The average particle size of carbon black is 0.0005 to 0.4 μm, and particularly 0.001 to 0.2 μm.
It is preferably within the range of m. Average particle size is 0.0
Carbon black with a diameter of less than 005 μm cannot be easily obtained, and therefore has little industrial significance. The average particle size is 0.4
If it exceeds μm, sufficient dispersibility may not be imparted to the obtained carbon black graft polymer.

On the other hand, the polymer used for forming a polymer portion by being grafted on such carbon black includes a segment (A) having a reactive group capable of reacting with a functional group on the surface of carbon black, A block or graft type polymer having substantially no reactive group and a segment (B) having a higher affinity for the dispersion of the recording medium liquid than the segment (A).

As the block or graft type polymer, one having a simple structure such as an AB type block copolymer shown in FIG. 2 (a) or an AB type graft copolymer shown in FIG. 2 (b) is used. Without limitation, a B-A-B type block copolymer shown in FIG. 2 (c), or a more advanced alternating block copolymer, formed by grafting a plurality of B segments shown in FIG. 2 (d) on an A segment. Various types such as comb-shaped graft copolymers and star-shaped graft copolymers shown in FIG. 2 (e) are included. In the figure, X represents a reactive group. FIG. 2 (f)
Represents a state in which these various block or graft type polymers are bonded to the surface of the carbon black particles (CB). In short, at least one segment ( The block or graft polymer may have any morphology as long as B) can be oriented to the outside from the surface of the carbon black particles with a certain degree of freedom. Further, for example, in the segment (A), Even if it has a plurality of types of segments to be classified (the same applies to the segment (B)), the segment (A) and the segment (B) have different properties, for example, an intermediate property between them. Or “fluctuation” (movement) of the graft chain in the medium solution that extends the graft chain
Other type of segment (hereinafter referred to as (C) segment) having a function of increasing or decreasing the
May be arranged in the middle of the segment (A) and the segment (B). Here, the (C) segment may or may not have a reactive group, but it is generally preferable to have no reactive group from the viewpoint of improving the graft efficiency. it is conceivable that. Further, in some cases, it is possible to introduce a reactive group or the like into the (C) segment so that they can be cross-linked with each other. Although referred to as the (C) segment from the above description, the (C) segment can be roughly classified into either the segment (A) or the segment (B) as described above.

In such a block or graft type polymer, the reactive group contained in the segment (A) reacts with a functional group present on the surface of carbon black to convert the polymer into carbon black. The reactive group is not particularly limited as long as it can contribute to grafting, and various reactive groups can be used.

Here, in order to make the grafting more reliable and stable, it is desired that the polymer portion is bonded to carbon black through a covalent bond, and in particular, an ester bond, a thioester bond, an amide bond, At least one bond selected from the group consisting of an amino bond, an ether bond, a thioether bond, a carbonyl bond, a thiocarbonyl bond and a sulfonyl bond, and at least one member selected from the group consisting of an ester bond, a thioester bond and an amide bond. It is desired to be a combination of
Considering such points, the reactive group is an epoxy group,
At least one selected from the group consisting of a thioepoxy group, an aziridine group, an N-hydroxyacrylamide group and an oxazoline group is preferable, or two or more types are preferable. The reactive groups for carbon black are not necessarily limited to these, but when a polymer having a group other than these reactive groups is used, the type of carbon black that can be used may be limited. The reason that the polymer preferably has the reactive group is that regardless of the type and state of the carbon black that can be used, the carbon black and the polymer are added with very high grafting efficiency even under mild conditions. To react. In particular, when carbon black has a carboxyl group as a surface functional group as described above, the carboxyl group is an epoxy group, a thioepoxy group, an aziridine group,
It is desirable because an irreversible addition reaction is carried out in a high yield with an N-hydroxyacrylamide group or an oxazoline group by thermal reaction, and the above-mentioned covalent bond is formed between the carbon black portion and the polymer portion by this addition reaction.

The method of introducing these reactive groups into the polymer (segment (A) portion) will be described later.

The segment (A) having such a reactive group needs to have a low affinity for the target medium due to its segment chain structure. It should be noted that the low affinity referred to here is only relative to the other segment (B), and therefore, the segment (A) may have various types depending on the type of the target medium or the configuration of the segment (B). However, it cannot be generally specified. However, from another perspective,
It is desirable that the segment (A) has a high affinity for carbon black because it exhibits better orientation to carbon black. From this point, the segment (A) has a main chain mainly containing a carbon-carbon bond, and more preferably contains an aromatic ring such as a benzene ring, a naphthalene ring or an indene ring in the main chain. And a reactive group as described above in the molecule, while the segment (B) is
A skeleton structure having fewer carbon-carbon bonds than the segment (A), particularly having less aromatic rings, such as a polysiloxane structure;
Alternatively, it is desirable to include many bonds other than carbon-carbon bonds such as ether bonds and ester bonds.

However, if the segment (A) is composed of only a substantially high degree of condensed polycyclic structure, the rigidity of the segment (A) is extremely increased, and the carbon black surface is grafted onto the carbon black during grafting. Since it may be difficult for the segment (A) to approach each other, it is desirable to have an appropriate linear structure.

As described above, the chain structure of the segment (A) can be appropriately selected according to the chain structure of the segment (B) selected from the viewpoint of dispersibility to be imparted to carbon black. , For example, styrenic monomers,
Various vinyl-based polymers, such as homopolymers or copolymers of (meth) acrylic monomers, alkylene-based monomers, polyesters, polyethers, etc. (having the above-mentioned reactive groups)
It may be a polymer chain, but of these, a vinyl-based polymer, in particular, a vinyl-based monomer component having an aromatic ring is used.
Various segments (B) selected according to the liquid medium to be used are vinyl polymers containing at least 60 mol% and more preferably at least 60 mol% and having a reactive group.
It is desirable because it can be combined with.

Further, in view of economic efficiency, a homopolymer or a copolymer mainly composed of a styrene monomer and a (meth) acrylic monomer, particularly 50 mol% or more of a styrene monomer component, Is preferably a polymer chain containing 60 mol% or more (having the above reactive group).

However, in the present invention, if the segment (A) having a reactive group has a sufficiently lower affinity than the segment (B) for the target medium in its segment chain structure, the segment (A) is not always necessary. ) Need not have a high affinity for carbon black,
Even if there is no substantial difference in affinity between the segment (A) and the segment (B) for carbon black, or even if the affinity is lower than that of the segment (B), it can be sufficiently used. In some cases, the segment (B) side may have a styrene structure, for example.

On the other hand, the segment (B) is, for example, a polysiloxane-based structure, a poly (meth) acrylic-based structure, a polyalkylene glycol, etc. depending on the properties to be imparted to the carbon black such as the dispersibility in the liquid medium used. A suitable one is selected from polymer chains having a polyether structure, a polyester structure, a polyalkylene structure, a polyamide structure, a polyimide structure, a polyurethane structure, etc.

For example, the polysiloxane structural chain is excellent in the dispersibility in a liquid medium having a low polarity, and is excellent in water repellency, mold releasability, heat resistance, weather resistance, flexibility, low viscosity and the like. And for the purpose of imparting that there is no low temperature brittleness,
Further, the (meth) acrylic chain is introduced with various (meth) acrylic ester monomer components to impart a wide range of hydrophilicity-hydrophobicity (for example, a (meth) acrylic acid hydroxyalkyl ester is introduced. The polyalkylene glycol chain is hydrophilic,
For the purpose of imparting properties such as lubricity, flexibility and antistatic,
Each can be adopted.

As a method for obtaining a polymer having such a segment (A) having a reactive group and a segment (B) having a high affinity for a liquid medium to be used,
It is not particularly limited, and it can be produced by appropriately combining various known block or graft polymer polymerization techniques with reactive polymer production techniques.

As a method of obtaining a graft type polymer,
For example, in the presence of a high molecular weight polymer to be a graft chain, a method of polymerizing a polymer to be a main chain by solution polymerization, emulsion polymerization, bulk polymerization or suspension polymerization of a polymerization initiator and a polymerizable monomer. It has been known. However, when the high molecular weight product does not have a radically polymerizable functional group, the resulting graft copolymer contains a large amount of ungrafted polymer, which has the drawback of low grafting efficiency. There is. Therefore, it is preferable to use a radical-polymerizable polymer as the polymer. Such a radical-polymerizable high-molecular weight substance is generally called a "macromonomer", and is a high-molecular-weight substance having a radical polymerizable group at one end, for example, a (meth) acroyl group, a styryl group, and the like. It is obtained by reacting a polymer having a carboxyl group at one terminal with a radically polymerizable monomer having a glycidyl group in an organic solvent (for example, in JP-B-43-11224, in an organic solvent). A method is disclosed in which a prepolymer obtained by radical polymerization of a radically polymerizable monomer in the presence of mercaptoacetic acid is reacted with glycidyl methacrylate in the presence of a dimethyllaurylamine catalyst.

Therefore, for example, in order to obtain the graft copolymer according to the present invention, the radical-polymerizable high molecular weight compound (b) as the component for forming the segment (B) as described above.
In the presence, the polymerizable monomer (a) having a reactive group for carbon black in the molecule as described above and other polymerizable monomer (c) forming the skeleton of the segment (A) optionally blended. ) Polymerize.

As the polymerizable monomer (a) having a reactive group for carbon black in the molecule,

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(However, R ¹ in these formulas represents hydrogen or a methyl group, and n is 0 or an integer of 1 to 20.) Epoxy group-containing polymerizable monomers represented by formulas such as ;

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(However, R ¹ and n in these formulas are the same as in the case of the epoxy group-containing polymerizable monomer.) And the like.

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[0141]

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Aziridine group-containing polymerizable monomers represented by the following: 2-vinyl-2-oxazoline, 2-vinyl-4
-Methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-vinyl-4-ethyl-2-oxazoline, 2-vinyl-5-ethyl-2-oxazoline, 2-isopropenyl-2- Oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, 2-isopropenyl-4-ethyl-2-oxazoline, 2-isopropenyl-5-ethyl- Oxazoline group-containing polymerizable monomers such as 2-oxazoline and 2-isopropenyl-4,5-dimethyl-2-oxazoline; N-hydroxymethyl acrylamide, N-hydroxyethyl acrylamide, N-hydroxybutyl acrylamide, N- Hydroxyisobutylacrylamide, N-hydroxy-
2-ethylhexyl acrylamide, N-hydroxycyclohexyl acrylamide, N-hydroxymethyl methacrylamide, N-hydroxyethyl methacrylamide, N-hydroxybutyl methacrylamide, N-hydroxyisobutyl methacrylamide, N-hydroxy-
N-hydroxyalkylamide group-containing polymerizable monomers such as 2-ethylhexyl methacrylamide, N-hydroxycyclohexyl methacrylamide; and the like, and one or more selected from these groups should be used. You can

Further, as the polymerizable monomer (c) which can be used, if necessary, in order to form the segment (A) into the desired skeleton as described above, the above-mentioned monomer (a) and those described later are used. It is not particularly limited as long as it can be copolymerized with the radically polymerizable high molecular weight compound (b) as a component for forming the segment (B), depending on the molecular structure of the segment (A) to be obtained. , For example, styrene, o
-Methyl styrene, m-methyl styrene, p-methyl styrene, α-methyl styrene, p-methoxy styrene,
p-tert-butylstyrene, p-phenylstyrene, o
-Styrene monomers such as chlorostyrene, m-chlorostyrene, p-chlorostyrene; acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, acrylic acid Stearyl, 2-ethylhexyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, methacrylic acid 2
-Acrylic acid or methacrylic acid type monomers such as ethylhexyl and stearyl methacrylate; ethylene, propylene, butylene, vinyl chloride, vinyl acetate, acrylonitrile, acrylamide, methacrylamide, N-vinylpyrrolidone, etc. More than one species can be used as appropriate.

On the other hand, the radical-polymerizable high molecular weight compound (b) for constituting the segment (B) component has a desired polymer chain, for example, polysiloxane structure, poly (meth) acrylic structure, polyalkylene glycol, etc. The polyether structure, the polyester structure, the polyalkylene structure, the polyamide structure, the polyimide structure, the polyurethane structure or the like having a reactive group at one end of the polymer chain may be used.

For example, when the segment (B) has a polysiloxane-based structure, the polysiloxane-based structure includes a polydimethylsiloxane group, a polydimethylsiloxane group substituted with a partial alkyl group and a polydimethylsiloxane group substituted with a partial aryl group. Examples thereof include those containing polyorganosiloxane such as dimethylsiloxane group and tris (trialkylsiloxy) silylpropyl group.

Therefore, examples of the radical-polymerizable high molecular weight compound (b ₁ ) having a polysiloxane structure include (meth) acryloyl group-containing polydimethylsiloxane, styryl group-containing polydimethylsiloxane (meth) acryloyl group-containing partial octyl substitution. Polymerizable polysiloxanes such as polydimethylsiloxane, styryl group-containing partially octyl-substituted polydimethylsiloxasan, styryl group-containing partially phenyl-substituted polydimethylsiloxane, and tris (trimethylsiloxy) silylpropyl (meth) acrylate are listed. It is possible to use one kind or two or more kinds, and the following are particularly desirable.

[0147]

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(In the formula, B represents —COO— or a phenylene group, R ¹ represents a hydrogen atom or a methyl group,
R ² is an alkylene group having 1 to 6 carbon atoms, R ^{3 to} R ¹³ are the same or different and each represents an aryl group, an alkyl group having 1 to 6 carbon atoms or an alkoxyl group having 1 to 10 carbon atoms, and a and b Are the same or different and each represents an integer of 0 to 10, and n represents an integer of 0 to 200. Similarly, in the case where the segment (B) has a polymeth (acryl) -based structure, the radical-polymerizable polymer (b ₂ ) may be, for example, the one shown below.

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(In the formula, R ¹ and R ² are the same or different and each represents a hydrogen atom or a methyl group, R ³ represents an alkyl group having 1 to 25 carbon atoms, and X is an arbitrary connecting chain, (Y represents an initiator terminal or H atom, and n represents an integer of 0 to 500.)

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[0152] ^{(wherein, R 1, R 2, R} 4 are the same or different and represent a hydrogen atom or a methyl group, R ^3,
R ⁵ is the same or different and represents an alkyl group having 1 to 25 carbon atoms, X is an arbitrary connecting chain, Y is an initiator terminal or H atom, and m and n are the same or different and are 0 to 5 respectively.
Indicates an integer of 00. )

[0153]

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(In the formulae, R ₁ and R ₂ are the same or different and each represents a hydrogen atom or a methyl group, R ₃ represents an alkylene group having 1 to 25 carbon atoms, and R ₄ represents 1 to 25 carbon atoms.
X is an arbitrary connecting chain, Y is an initiator terminal or H atom, and n and m are the same or different and each represents an integer of 0 to 500. When the segment (B) has a polyalkylene glycol structure, the radical-polymerizable high molecular weight compound (b ₃ ) may be, for example, those shown below.

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(In the formula, R ¹ , R ² , and R ³ are the same or different and each represents a hydrogen atom or a methyl group, and n is 0.
Indicates an integer of ˜500. )

[0157]

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(In the formula, R ¹ , R ² , R ³ , R ⁴
Are the same or different and represent a hydrogen atom or a methyl group,
n and m are the same or different and each represents an integer of 0 to 500. Further, in the case where the segment (B) has a polystyrene structure, a radical-polymerizable high molecular weight compound (b ₄ )
For example, the following may be used.

[0159]

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(In the formula, R ₁ represents a hydrogen atom or a methyl group, X represents an arbitrary connecting chain, Y represents an initiator terminal or H atom, Z represents a hydrogen atom, a halogen substituent or a carbon number of 1). .About.8, and n represents an integer of 0 to 500.) The linking chain X shown in the above formula group is, for example, "Chemistry and Industry of Macromonomer" (supervised by Yuya Yamashita,
It is described in detail in IPC Co., Ltd., September 20, 1989, and any of those shown therein can be used.

As a polymerization method for obtaining such a polymer, a known polymerization method can be used. For example,
Bulk polymerization method, suspension polymerization method, emulsion polymerization method, solution polymerization method and the like can be mentioned. Among them, the solution polymerization method using a radical catalyst is preferable.

As the radical catalyst, any radical catalyst which is usually used for the polymerization of vinyl monomers can be used. Typical examples include azo compounds such as 2,2'-azobisisobutyronitrile and 2,2'-azobis (2,4-dimethylvaleronitrile); benzoyl peroxide, di-tert-butyl. Peroxide, ter
Examples thereof include peroxide compounds such as t-butyl peroctoate and tert-butyl peroxy-2-ethylhexanoate, which are usually 0.2 to 10 parts by weight, preferably 100 parts by weight of the monomer. Is used in the range of 0.5 to 5 parts by weight. Further, the solvent is appropriately selected depending on the type of the monomer and the radical-polymerizable high molecular weight substance used.

After completion of the polymerization, the obtained solution of the polymer having a reactive group may be used as it is for the reaction with carbon black, or the solvent of the solution may be distilled off to take out the polymer. it can.

As another method for obtaining the graft type polymer which can be used in the present invention, for example, a compound having a reactive group for carbon black is added to the segment (A) having a group capable of reacting with the compound. In addition, a method of reacting with a precursor polymer obtained by grafting the segment (B) on the segment (A) to introduce the reactive group into the precursor polymer can be mentioned.

Examples of the above-mentioned compound include a compound having two or more kinds of the above-mentioned reactive groups for carbon black in the molecule, a compound having two or more kinds of the above-mentioned reactive groups for carbon black in the molecule, Examples thereof include compounds having one or more of the above-mentioned reactive groups for carbon black and a functional group other than the above-mentioned reactive groups in the molecule.

However, the above-mentioned functional group is a group other than an epoxy group, a thioepoxy group, an aziridine group, an oxazoline group, and an oxazoline group, and is capable of reacting with the reactive group of the above-mentioned precursor polymer. It is a thing. Examples of the reactive group contained in the precursor polymer include an isocyanate group, an amino group, a carboxyl group, a hydroxyl group and a vinyl group.

Further, as a method for obtaining a block-type polymer, for example, anion living polymerization method, cation living polymerization method, iniferter method and the like are known. Further, as another method, the segment (A) or segment ( In the radical polymerization of the monomer of B) (the segment (A) in the present invention introduces a reactive group, the segment (B) is preferable), a thiolcarboxylic acid,
Alternatively, a polymer obtained by polymerizing a compound containing a thioester and a thiol group in the molecule such as 2-acetylthioethylthiol, 10-acetylthiodecanethiol and the like in a molecule is polymerized with an alkali such as sodium hydroxide or ammonia. A method is known in which a polymer having a thiol group at one end is treated to radically polymerize the monomer component of the other segment in the presence of the obtained polymer having a thiol group at one end. .

Therefore, in order to obtain the block copolymer according to the present invention, the known method as described above is appropriately changed, and the polymerizable monomer of the segment (A) is prepared in the same manner as in the case of obtaining the graft copolymer. Whether the reactive monomer is introduced into the segment (A) during the polymerization of the block copolymer by using the polymerizable monomer (a) having a reactive group as described above at least in part as a monomer Alternatively, such a reactive group may be introduced into the segment (A) after the block copolymer is polymerized.

To understand this, to give just one example, as a synthetic method by the anion living method, 4-vinylbenzyllithium was used, and styrene was added to a nitrogen stream in tetrahydrofuran to polymerize it, followed by methacrylic acid at a low temperature. To obtain an AB block (styrene-methyl methacrylate) copolymer by polymerizing methyl, and then converting the vinyl group at the starting end of the segment (A) into an epoxide group using 3-chloroperbenzoic acid. By this, a reactive group having reactivity with carbon black can be introduced into the segment (A). Alternatively, 4-
Using vinylbenzyllithium, styrene is added to a stream of nitrogen in tetrahydrofuran to polymerize to obtain a segment (A) portion, and then glycidyl methacrylate is added to the reaction system to give a segment having a reactive group in the segment (A). It is also possible to employ a method such as binding the above, and then polymerizing methyl methacrylate at a low temperature.

The molecular weight of the thus obtained graft or block type polymer according to the present invention is not particularly limited, but the effect of grafting to carbon black and workability during reaction with carbon black are taken into consideration. Then, the above-mentioned molecular weight is 1000-1000.
The range is preferably 000, more preferably 5
It is in the range of 000 to 100,000.

Further, the molecular weights of the segment (A) and the segment (B) in this polymer according to the present invention are not particularly limited, and depend on the kinds of polymer chains constituting these segments and the like. However, from the viewpoint of graft efficiency with respect to carbon black, it is preferable that the segment (A) has an average molecular weight in the range of 300 to 100,000, more preferably 1000 to 50,000, and the dispersibility modification to be imparted to the carbon black. From the viewpoint of the effect, the segment (B) preferably has an average molecular weight of 300 to 100,000, more preferably 500 to 50,000. Further, the number of reactive groups contained in the segment (A) of the polymer is not particularly limited, but the polymer 1
It is desired to have an average of 50 to 1, more preferably about 20 to 1 per molecule.

In the present invention, the complexing or grafting of the above-mentioned graft or block type polymer with carbon black is carried out in a liquid medium in which the obtained carbon black graft polymer is to be dispersible or close thereto. It is carried out by heating in the presence of a dispersion medium liquid consisting of a medium having properties. That is, the dispersion medium liquid has a high affinity or compatibility with the segment (B) of the polymer and a low affinity or compatibility with the segment (A).

Therefore, the dispersion medium liquid used is appropriately selected according to the combination of the segment (A) and the segment (B) in the polymer.

For example, the segment (A) in the polymer
Has a polystyrene structure and the segment (B) has a polysiloxane structure, the dispersion medium liquid used is polydimethylsiloxane, partially octyl-substituted polydimethylsiloxane, partially phenyl-substituted polydimethylsiloxane. Silicone oils such as fluorosilicone oils are preferred.

Further, for example, when the segment (A) in the polymer has a polystyrene structure and the segment (B) has a hydrophobic (meth) acrylic structure such as polymethylmethacrylate, it is used. Examples of the dispersion medium liquid include cellosolves such as methyl cellosolve and ethyl cellosolve; methyl acetate, ethyl acetate,
Preferred are esters such as butyl acetate; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; aprotic polar solvents such as pyrrolidone, N, N-dimethylformamide, and dimethyl sulfoxide.

Further, for example, the segment (A) in the polymer has a polystyrene structure, and the segment (B) has a hydrophilic (meth) acrylic structure such as methyl methacrylate-hydroxymethyl methacrylate copolymer. In this case, as the dispersion medium liquid used, alcohols such as water, water-alcohol mixed liquid, methyl alcohol and ethyl alcohol; esters of methyl cellosolve, ethyl cellosolve and butyl cellosolve; ketones such as acetone; pyrrolidone, N, N −
Dimethylformamide, dimethylsulfoxide and the like are preferable.

Further, for example, when the segment (A) in the polymer has a polystyrene structure and the segment (B) has a polyalkylene glycol structure, for example, the dispersion medium liquid used is water. ,
Preferred are water-alcohol mixed solutions, alcohols such as methyl alcohol and ethyl alcohol; glycols such as ethylene glycol and diethylene glycol, and polyhydric alcohols such as glycerin.

When the carbon black and the polymer are heated in the presence of such a dispersion medium liquid, other substances such as a polymer and a polymerizable monomer which do not correspond to the polymer may be further present. .

The conditions for complexing or grafting are, for example, 40 to 300 ° C., preferably 70 to 300 ° C.
0.5 to 10 hours, preferably 2 at a temperature of 250 ° C.
It can be illustrated that the mixture is stirred for 5 hours. If the heating temperature is lower than 40 ° C, grafting may not proceed, which is not preferable. If it exceeds 300 ° C., the polymer component may deteriorate, which is not preferable.

As a reaction procedure, carbon black and the polymer and the dispersion medium may be charged into a reaction apparatus and mixed with heating.

As the reaction device, a stirring tank used for ordinary stirring and a kneading machine such as a ball mill, a mixer or a kneader used for kneading can be used, but it is particularly preferable to store the fluid to be treated therein. Vessel, a stirring bar rotating inside the vessel, a heating device for heating the fluid to be treated contained in the vessel, and a wet dispersion treatment comprising a plurality of granular dispersion media contained in the vessel It is a device. Many wet dispersion treatment devices or wet pulverization treatment devices that perform stirring or crushing by using a stirring element and a granular dispersion medium such as beads together are well known, but in the present invention, such treatment is performed. It is used as a device configuration in which a heating device for heating a fluid to be processed is added to the device. When the apparatus having such a configuration is used, carbon black having extremely high efficiency and a sufficiently small particle size (that is, the polymer is grafted to the carbon black satisfactorily crushed from the secondary aggregation state). A graft polymer can be obtained.

The mixing ratio of the carbon black and the polymer during heating depends on the type of the polymer used, the characteristics required for the recording medium liquid to be obtained, and the like. Therefore, although it cannot be specified in general, it is desirable that the amount of the polymer is 1 to 1000 parts by weight, more preferably 2 to 500 parts by weight, relative to 100 parts by weight of carbon black. That is, if the amount of the polymer is less than 1 part by weight, it may be difficult to sufficiently modify the surface properties of the carbon black. On the other hand, if the amount exceeds 1000 parts by weight, the amount of the polymer bonded to the carbon black may increase. This is because the amount becomes large, which is not economical and may impair the originally required characteristics of carbon black.

The average particle diameter of the carbon black graft polymer according to the present invention thus obtained is 0.00
It is preferably in the range of 1 to 0.5 μm, particularly 0.005 to 0.2 μm. A carbon black graft polymer having an average particle diameter of less than 0.001 μm has little industrial significance because carbon black as a raw material cannot be easily obtained. When the average particle size exceeds 0.5 μm, sufficient dispersibility may not be obtained.

In the carbon black graft polymer according to the present invention, the ratio of the carbon black portion to the polymer portion is 100 parts by weight of the former and 1 to 1000 parts by weight of the latter,
It is particularly preferably 5 to 500 parts by weight. The latter is 1
If the amount is less than the amount by weight, the resulting carbon black graft polymers may aggregate with each other, resulting in a problem that sufficient dispersibility cannot be obtained in a liquid medium. The latter is 1
If it exceeds 000 parts by weight, the polymer portion may be grafted more than necessary, and the characteristics inherent to carbon black may not be exhibited.

The carbon black graft polymer obtained by the above-mentioned method is remarkably excellent in dispersibility in various substances such as organic polymers, water and organic solvents.
Further, in general, in addition to the high electric insulation, the polymer segment (B) introduced therein has many characteristics. For example, when the polymer segment (B) is a polysiloxane structural chain, it is excellent in water repellency, releasability, heat resistance, weather resistance, flexibility, low viscosity, etc., and low temperature brittleness. If the characteristic is that the (meth) acrylic chain is not present, and various (meth) acrylic ester monomer components are introduced, a particularly wide hydrophilicity-hydrophobicity is further exhibited by the polyalkylene glycol chain. In such a case, properties such as hydrophilicity, lubricity, flexibility and antistatic property are imparted.

However, the recording medium liquid according to the present invention may be any liquid as long as it contains the above carbon black graft polymer as a colorant component, and the liquid medium and other components are not particularly limited. , A method of an inkjet recording apparatus using the recording medium liquid (for example, a piezoelectric pressure method, a heating and pressure method, etc.), and its ejection conditions (for example, in the pressure transfer pressure method, a drive voltage and a drive frequency of a piezoelectric element) , The shape and material of the discharge orifice, the discharge orifice diameter, etc., and in the heating and pressurizing method, the amount of thermal energy that acts per unit time, the type of heat exchange energy, the shape of the discharge orifice, the discharge orifice diameter, etc. Liquid physical properties (viscosity, surface tension, conductivity, boiling point, thermal conductivity, water-soluble or water-insoluble) suitable for the type of recording agent (paper, film, etc.) So as to have equal) may be selected as appropriate the composition.

The liquid medium used is water;
Methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, Monohydric alcohol solvents such as furfuryl alcohol and tetrahydrofurfuryl alcohol; for example, ethylene glycol,
Polyhydric alcohol solvents such as diethylene glycol, triethylene glycol, propylene glycol, tetraethylene glycol, polyethylene glycol, glycerin, 1,2,6-hexanetriol, and thiodiglycol; for example, acetone, methyl ethyl ketone, methyl propyl ketone, methyl amyl. Ketones, ketones such as dichlorohexanone, diacetone alcohol and keto alcohol solvents; for example, ethyl ether, butyl ether, tetrahydrofuran, dioxane, or ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether,
Propylene glycol monomethyl ether, propylene glycol monoethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether and other ether solvents; for example, ethyl formate, methyl acetate, ethyl acetate, phenyl acetate, Ester-based solvents such as ethyl lactate, ethylene carbonate, propylene carbonate, ethylene glycol monoethyl ether acetate; amine solvents such as monoethanolamine, diethanolamine, triethanolamine; amide solvents such as dimethylformamide, dimethylacetamide; , Pyrrolidone, N-methyl-2-pyrrolidone, 1,3
-Nitrogen-containing cyclic compound solvents such as dimethyl-2-imidazolidinone; for example, hydrocarbon solvents such as hexane, octane, cyclopentane, benzene, toluene, xylol; carbon tetrachloride, trichloroethylene, tetrachloroethane, dichlorobenzene, etc. The halogenated hydrocarbon solvent and the like may be appropriately selected so as to satisfy various properties required for the recording medium as described above, and may be used alone or in combination of plural kinds.

Among these liquid media, water, monohydric alcohols or polyhydric alcohols, cellosolve, cellosolve, etc. are taken into consideration in view of availability, economy, environment resistance, ease of preparation of recording media, and the like. A liquid medium such as acetate is desirable, and water and ethanol are particularly desirable. Further, especially from the viewpoint of preventing ink clogging, diethylene glycol and thiodiglycol are preferable, and from the viewpoint of image density and ejection stability, a nitrogen-containing cyclic compound or an ether compound of polyalkylene oxide is preferable, and further, frequency response. Therefore, it is preferable to use a lower alcohol or to add a surfactant as described below.

The blending amount of the above carbon black graft polymer with respect to the liquid medium in the recording medium liquid according to the present invention is not particularly limited, and for example, the pigment concentration is 1 to 20% by weight, preferably 2 to 12% by weight. The amount of the carbon black graft polymer may be adjusted so as to be within the range, but it is 1 to 100 parts by weight, and more preferably 2 to 50 parts by weight with respect to 100 parts by weight of the liquid medium.

The recording medium liquid according to the present invention comprises, as a basic constituent component, the liquid medium as described above and a colorant component composed of a carbon black graft polymer. Various additives such as a regulator, a surface tension regulator, a pH regulator, a resistivity regulator, a wetting agent, an infrared absorption heat generating agent, a resin component, and a colorant component within a range not impairing the effect of the present invention. Various dyes and pigments may be added as.

The viscosity adjusting agent and the surface tension adjusting agent are mainly applied to the recording material by flowing through the nozzle at a sufficient flow rate according to the recording speed, preventing the recording medium from wrapping around at the orifice of the nozzle. It may be added for the purpose of preventing bleeding.

As the viscosity adjusting agent and the surface tension adjusting agent, any known one may be used as long as it does not adversely affect the liquid medium and the colorant component to be used. Examples include polyvinyl alcohol, hydroxypropylcellulose, carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, water-soluble (meth) acrylic resin, polyvinylpyrrolidone, gum arabic, starch and the like, and examples of the surface tension adjusting agent include , Anionic surfactants such as polyethylene glycol ether sulfuric acid and ester salts, poly-2-vinylpyridine derivatives, poly-4-
Cationic surfactants such as vinyl pyridine derivatives, nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan monoalkyl ester, polyoxyethylene alkylamine Examples thereof include various surface active agents such as, etc .; amine acids such as diethanolamine, propanolamine, and morpholinic acid; basic substances such as ammonium hydroxide and sodium hydroxide; and substituted pyrrolidones such as N-methyl-2-pyrrolidone.

These viscosity adjusting agents and surface tension adjusting agents can be used in combination of a plurality of kinds, if necessary. The addition amount of the viscosity adjusting agent and the surface tension adjusting agent depends on the type of the liquid medium used, the addition amount of the colorant component, and the like. 0.1 to 30 parts by weight of the agent and 0.01 to 10 parts by weight of the surface tension adjusting agent are suitable.

The pH adjusting agent has a predetermined pH value in order to prevent chemical stability of the recording medium liquid, for example, change in physical properties due to long-term storage and prevention of sedimentation or aggregation of the colorant component and other components. Can be added as necessary. pH
Examples of the regulator include lower alkanolamines; monovalent hydroxides such as alkali metal hydroxides; ammonium hydroxide.

When recording by recording the liquid droplets of the recording medium liquid according to the present invention, the specific resistance of the recording medium liquid is an important factor for the charging characteristics. In the case of such a recording method, a specific resistance adjusting agent may be added so as to adjust the specific resistance value of the recording medium liquid within a predetermined range. Examples of the resistivity adjusting agent include inorganic salts such as ammonium chloride, sodium chloride and potassium chloride; water-soluble amines such as triethanolamine and quaternary ammonium salts.

As the wetting agent that can be used in the recording medium solution of the present invention, various known wetting agents can be used. Examples thereof include polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol and butylene. Alkylene glycol such as glycol and hexylene glycol;
Examples include alkylene glycols such as ethylene glycol methyl ether, diethylene glycol methyl ether, and diethylene glycol ethyl ether; alkyl ethers of dialkylene glycol; glycerin; alkoxytriglycols such as methoxytriglycol and ethoxytriglycol; and N-vinyl-2-pyrrolidone oligomer. These can be used alone or in combination of two or more. Most of these also act as a liquid medium.

When the recording medium liquid according to the present invention is heated and recorded using electromagnetic wave energy, especially infrared rays,
It is also desirable to add an infrared absorbing heat generating agent to the recording medium liquid. As described above, in the present invention, carbon black is contained as a colorant component, and carbon black also acts as an infrared absorbing exothermic agent, but as an infrared absorbing exothermic agent, other than this, for example,
Dyes such as water-soluble nigrosine, modified water-soluble nigrosine, alcohol-soluble nigrosine, etc., inorganic pigments such as ultramarine blue, cadmium yellow, red iron oxide, chrome yellow, etc., organic pigments such as azo-based, triphenylmethane-based, quinoline-based, anthraquinone-based, phthalocyanine-based, etc. Etc. can be used. Of course, many of these also act as colorant components.

Further, in order to enhance the film forming property and the film strength when the recording medium liquid according to the present invention is attached to the recording material, for example, a resin such as an alkyd resin, an acrylic resin, an acrylamide resin, polyvinyl alcohol, polyvinylpyrrolidone or the like. Ingredients may be added.

As described above, in the recording medium liquid according to the present invention, as the colorant component, the segment (A) having a reactive group capable of reacting with the functional group on the surface of carbon black and the reactive group are substantially contained. The case where a carbon black graft polymer obtained by grafting a polymer having a segment (B) which has a higher affinity for a liquid medium than the above segment (A) onto carbon black is described in detail. A segment (A) having a reactive group capable of reacting with a functional group on the pigment surface with respect to a pigment other than carbon black as a colorant component, and the segment (A) having substantially no reactive group. The same applies to the case of using a pigment composite polymer obtained by heating and mixing a polymer having a segment (B) having a higher affinity for a liquid medium than To the recording medium liquid can be prepared and can be expected same effect. It should be noted that the pigment to be used can be expected to have a great improvement effect particularly when it is based on an inorganic pigment.

[0200]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples. In the following, “parts” as a blending ratio indicates “parts by weight”.

Synthesis Example 1 A separable flask equipped with a stirring blade, an inert gas introduction tube, a reflux condenser and a thermometer was charged with ethanol 100.
Part, methoxy polyethylene glycol methacrylate having a double bond at one end (manufactured by Shin-Nakamura Chemical Co., Ltd., N
K ester M-230G) 75 parts, styrene 15 parts, isopropenyl oxazoline 10 parts, and 2,2 as an initiator.
′ -Azobis (2,4-dimethylvaleronitrile) (3 parts) was charged, and a polymerization reaction was carried out at 75 ° C. for 5 hours under a N ₂ stream to obtain ethylene having an oxazoline group in the molecule as a reactive group having a nonvolatile content of 50%. A polymer solution (1) containing a glycol chain was obtained.

Synthesis Example 2 A flask similar to that used in Example 1 was charged with lauryl alcohol (ethylene oxide) ₁₅ glycidyl ether having an epoxy equivalent of 1040 (Denacol EX manufactured by Nagase Kasei Co., Ltd.).
-171) 1040 parts, 500 parts of ethanol were charged,
Acrylic acid (72 parts), a catalytic amount of pyridine and 150 ppm of hydroquinone were added, and the mixture was reacted at 70 ° C for 2 hours.
Thereafter under reduced pressure, ethanol was distilled off, lauryl alcohol having a double bond at one terminal (ethylene oxide) ₁₅
I got

75 parts of lauryl alcohol (ethylene oxide) ₁₅ having a double bond at one end thereof, 100 parts of ethanol, 15 parts of styrene and 10 parts of glycidyl methacrylate were added to 2,2'-azobis (2,4-
Dimethyl valeronitrile) 3 parts, and under N ₂ flow 75
A polymerization reaction was carried out at 6 ° C for 6 hours. As a result, the nonvolatile content 5
A polymer solution (2) containing 0% lauryl alcohol (ethylene oxide) ₁₅ chains was obtained.

Synthesis Example 3 In Synthesis Example 1, methoxy polyethylene glycol methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester M-230G) was replaced with methoxy polyethylene glycol methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., light ester 041MA). Was used in the same manner as in Synthesis Example 1 to obtain a polymer solution (3) having an ethylene glycol chain and having an oxazoline group as a reactive group having a nonvolatile content of 50%.

Synthesis Example 4 An oxazoline group was used as a reactive group having a nonvolatile content of 50% in the same manner as in Synthesis Example 1 except that 50 parts of ethanol and 50 parts of ethylene glycol were used instead of 100 parts of ethanol in Synthesis Example 1. A polymer solution (4) having an ethylene glycol chain therein was obtained.

Example 1 In a separable flask equipped with a temperature sensor, a stirring blade and a cooling tube, 30 parts of the polymer solution (1) having an ethylene glycol chain obtained in Synthesis Example 1 was added, and carbon black Special Black 250 (Degussa) was used. (Made by corporation) 10
And 1500 parts of zirconia beads.
After maintaining at 75 ° C. for 2 hours while stirring at a rotation speed of 600 rpm, the temperature was raised to 120 ° C. and the reaction was carried out for 1 hour while distilling ethanol off. Thereafter, the mixture was cooled, 75 parts of deionized water was added and dispersed, and the mixture was separated from the beads to obtain a carbon black dispersion (1).

Example 2 In a flask similar to that of Example 1, 30 parts of the polymer solution (2) containing ₁₅ chains of lauryl alcohol (ethylene oxide) obtained in Synthesis Example 2 and carbon black special black 250 (Degussa ( Co., Ltd.) and 1500 parts of zirconia beads. Rotation speed 600r
After maintaining at 75 ° C for 2 hours with stirring at pm,
The temperature was raised to 0 ° C., and the reaction was carried out for 1 hour while distilling ethanol off. Then cool, add 75 parts of deionized water,
It was dispersed and separated from the beads to obtain a carbon black dispersion (2).

Example 3 In the same flask as in Example 1, 12 parts of the polymer solution (3) obtained in Synthesis Example 3, 20 parts of carbon black Special Black 250 (manufactured by Degussa Co.) and deionized water were used. 75 parts and 1500 parts of zirconia beads were charged. While stirring at a rotation speed of 600 rpm, the temperature was raised to 95 ° C. to remove ethanol, and the reaction was further performed for 1 hour. Then, it was cooled and separated from the beads to obtain a carbon black dispersion (3).

Example 4 The same operation as in Example 3 was repeated except that the polymer solution (4) was used in place of the polymer solution (3) in Example 3,
A carbon black dispersion (4) was obtained.

Comparative Example 1 15 parts of lauryl alcohol (ethylene oxide) ₁₅ glycidyl ether (Denacol EX-171 manufactured by Nagase Kasei Kogyo KK), carbon black Special Black 250 (Degussa K.K.) were placed in the same flask as in Example 1.
10 parts) and 1500 parts of zirconia beads.

Then, the same operation as in Example 2 was carried out to obtain a carbon black dispersion (1) for comparison.

Comparative Example 2 Carbon black MA-100R (manufactured by Mitsubishi Chemical Corporation) 10
0 part, lauryl alcohol (ethylene oxide) ₁₅ glycidyl ether (Nagase Chemicals Co., Ltd., Denacol EX-171) 25 parts, polyethylene glycol (Sanyo Chemical Co., Ltd., PEG200 (degree of polymerization 4-5)) 7
5 parts were kneaded for 15 minutes at 150 ° C. and 100 rpm using a Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.) and cooled to obtain treated carbon (1). 20 parts of this treated carbon (1) and 80 parts of deionized water were mixed and dispersed with a stirrer to obtain a carbon black dispersion (2) for comparison.
I got

Comparative Example 3 Carbon Black Special Black 250 (manufactured by Degussa Co., Ltd.) 10 parts, polyethylene glycol 15 parts, surfactant (manufactured by Kao Corporation, Emulbun 985) 0.05
And 11.24 parts of deionized water were dispersed in a sand mill for 18 hours, 70 parts of deionized water was added so that the pigment concentration was 10% by weight, and the dispersion was further performed for 30 minutes to obtain a carbon black dispersion for comparison ( 3) was obtained.

Examples 1 to 4 and Comparative Examples 1 to 3
The long-term storability of the recording medium liquid was evaluated by the following method for each carbon black dispersion obtained in the above. The results are shown in Table 1.

<Long-term storage stability> Each carbon black dispersion was placed in a φ18 mm Pyrex test tube and held,
Dispersion stability was compared by allowing to stand at room temperature for 6 months.

[0216]

[Table 1]

Synthesis Example 5 Poly (methyl methacrylate-hydroxyethyl methacrylate) macromonomer 7 having methacroyl group at one end
5 parts, styrene 15 parts, isopropenyl oxazoline 1
0 part and 3 parts of azoisobutyronitrile were mixed with propylene glycol monomethyl ether acetate (PGM-
Ac) was dissolved in 100 parts to prepare a polymerizable monomer composition. Next, stirrer, reflux condenser, thermometer, dropping funnel,
PGM-Ac was added to a separable flask equipped with an N ₂ inlet.
50 parts were charged and the temperature was raised to 80 ° C. The above polymerizable monomer composition was charged in a dropping funnel and added dropwise for 3 hours to carry out polymerization at 80 ° C. 2 hours 8 more after dropping
Polymerization was continued at 0 ° C., then the temperature was raised to 120 ° C. and aging was carried out for 2 hours. Finally, a polymer solution (5) having a nonvolatile content of 40%
I got

Synthetic Example 6 The same operation as in Synthetic Example 5 was conducted except that the isopropenyloxazoline was not used in Synthetic Example 5, and the nonvolatile content was 40%.
A polymer solution (6) having no reactive group of was obtained.

Examples 5 to 10 A polymer solution (5) obtained in Synthesis Example 5 (23.4) was placed in a separable flask equipped with a thermometer, stirring blades, and a cooling tube.
Part, carbon black 31.2 parts, PGM-Ac10
1.4 parts and 800 parts of zirconia beads were charged. As the carbon black, six types having different particle sizes, oil absorption amounts, and pH values as shown in Table 2 were used. The reaction system was maintained at 100 ° C. for 2 hours while stirring at a rotation speed of 700 rpm. Then, it was cooled and separated from the beads to obtain carbon black dispersions (5) to (10).

Comparative Example 4 A carbon black for comparison was prepared in the same manner as in Example 5, except that the polymer solution (6) obtained in Synthesis Example 6 was used instead of the polymer solution (5) in Example 5. A dispersion (4) was obtained. The carbon black in this dispersion (4) was not grafted with the polymer.

[0221]

[Table 2]

With respect to the carbon black dispersions obtained in Examples 5 to 10 and Comparative Example 4, the dispersibility of carbon black in the recording medium liquid and the liquid stability were evaluated by the following methods.

<Dispersibility of Carbon Black> Each carbon black dispersion was coated on a glass substrate with a spinner and sufficiently dried, and then 20 ° gloss (gloss) was measured to evaluate the dispersibility. The results are shown in Table 3. In the case of carbon black, the better the dispersibility, the higher the gloss of the coating film (mirror surface) and the larger the gloss value.

<Liquid stability> First, the liquid stability viscosity was evaluated. 100m of each carbon black dispersion
The change in viscosity was measured over a period of 30 days in a 1-screw tube. The measurement was performed at 60 rpm using a B type viscosity system. FIG. 3 shows the obtained results. The stability was evaluated by observing the state of sedimentation when the carbon black dispersion was placed in a Pyrex test tube having a diameter of 18 mm and allowed to stand for 30 days.

[0225]

[Table 3]

As shown in Table 3, it was found that the dispersibility of the obtained carbon black graft polymer changed intricately depending on the particle size of the carbon black particles used as the raw material, the oil absorption amount, and the pH. However, it was confirmed that when the grafting is carried out, the gloss value is remarkably increased and the dispersibility is improved as compared with the ungrafted carbon black.

As shown in FIG. 3, in the comparative carbon black dispersion (4) obtained in Comparative Example 4, that is, the ungrafted carbon black particle dispersion, the viscosity of the solution increased with the passage of time. On the other hand, Example 5
It was confirmed that the viscosity of the carbon black dispersion (5) obtained in the above, that is, the carbon black graft polymer dispersion according to the present invention hardly changed. Although not shown in FIG. 3, the carbon black dispersions (6) to (10) according to Examples 6 to 9 show substantially the same change in viscosity with time as in the illustrated carbon black dispersion (5). It was hardly seen. From this result, by grafting the polymer on the surface of the carbon black particles,
It was considered that the polymer acts as if it were a surfactant and could contribute to the stability of the carbon black particles in the liquid.

As a result of observing sedimentation of the carbon black dispersion, sedimentation was not confirmed at all in the grafted ones (Examples 5 to 10) regardless of the kind of carbon black. On the other hand, sedimentation was confirmed in the non-grafted dispersion (Comparative Example 4).

[0229]

As described above, the present invention is a recording medium liquid containing a liquid medium used in an ink jet recording method and a colorant component, wherein the colorant component is:
A segment (A) having a reactive group capable of reacting with a surface functional group of a pigment such as carbon black, and a segment having substantially no reactive group and having a higher affinity for a liquid medium than the segment (A). The liquid medium is a recording medium liquid containing a pigment composite polymer such as a carbon black graft polymer obtained by heating a polymer having a segment (B) The dispersibility of the colorant component in the medium and the long-term storage stability are excellent, and the pigment content such as carbon black in the pigment composite polymer as described above is extremely high. Is a good recording medium liquid having excellent water resistance and light resistance due to the use of a pigment-based colorant component.

In the present invention, the reactive group contained in the segment (A) is at least one or two or more selected from the group consisting of an epoxy group, a thioepoxy group, an aziridine group, an N-hydroxyacrylamide group and an oxazoline group. When it is one, it is possible to more reliably bond the reactive polymer to the surface of the solid fine particles, and it becomes a pigment composite polymer that exhibits more excellent dispersion stability, and to improve the long-term storage stability of the resulting recording medium liquid. You can

In the present invention, the segment (A) is obtained by polymerizing a vinyl-based monomer composition containing a vinyl-based monomer having at least a reactive group,
It contains a main chain having a carbon bond, particularly contains an aromatic ring in the polymer chain, and further, the segment (A) contains a vinyl-based monomer having an aromatic ring of 5
When the polymer is obtained by polymerization of a vinyl-based monomer composition containing 0 mol% or more and a vinyl-based monomer having a reactive group, the polymer is more reliably and efficiently complexed with a pigment. Or, it becomes a pigment composite polymer that can be grafted and exhibits more excellent dispersion stability, and the long-term storage stability of the resulting recording medium liquid can be improved.

In the present invention, the segment (B) is a polysiloxane structure, a poly (meth) acrylic structure, a polyether structure, a poly (meth) acrylonitrile structure, a polyester structure, a polyalkylene structure,
When it has at least one selected from the group consisting of a polyamide structure, a polyimide structure and a polyurethane structure, it is possible to exhibit more excellent dispersibility in various liquid media used.

Further, in the present invention, the average particle size of the carbon black used as the pigment is 0.0005 to 0.
Within the range of 4 μm, the average particle size of the obtained carbon black graft polymer can be set to about 0.001 to 0.5 μm, the dispersibility of the colorant component is further improved, and the sharpness of the image is Sharpness is improved.

Further, in the present invention, when the polymer is grafted with 1 to 1000 parts by weight of the above-mentioned polymer with respect to 100 parts by weight of the carbon black, most of the originally required characteristics of the carbon black are obtained. The surface properties can be satisfactorily modified without affecting, and the density and sharpness of the image formed by the recording medium liquid containing such a carbon black graft polymer are further improved.

In the present invention, when the carbon black has a carboxyl group and the carbon black is acidic carbon black having a pH of less than 6, the polymer can be grafted more reliably and stably, It is possible to enhance the dispersion stability in a recording medium liquid obtained by arranging such a carbon black graft polymer.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a state near the surface of carbon black when a carbon black graft polymer used in the present invention is produced.

2 (a) to 2 (e) are diagrams schematically showing various structural examples of the block or graft type polymer used in the present invention, and FIG. 2 (f) is these various block or graft polymers. It is a figure which shows typically the state which the polymer of the type couple | bonded with the carbon black particle (CB) surface.

FIG. 3 is a graph showing changes in viscosity with time of recording medium liquids obtained in Examples and Comparative Examples of the present invention.

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Tatsuto Matsuda 5-8 Nishiburi-cho, Suita-shi, Osaka Nippon Shokubai Co., Ltd.

Claims (4)

[Claims] 1. A recording medium liquid containing a liquid medium used in an inkjet recording method and a colorant component, wherein a segment having a reactive group capable of reacting with a functional group on the pigment surface as the colorant component ( It is obtained by heating a polymer having A) and a segment (B) substantially free of the reactive group and having a higher affinity for a liquid medium than the segment (A) with a pigment. A recording medium liquid containing a pigment composite polymer. 2. The recording medium liquid according to claim 1, wherein the pigment is carbon black. 3. The reactive group contained in the segment (A) is an epoxy group, a thioepoxy group, an aziridine group or N-
The recording medium liquid according to claim 1 or 2, which is at least one kind or two or more kinds selected from the group consisting of a hydroxyacrylamide group and an oxazoline group. 4. The segment (B) comprises a polysiloxane structure, a poly (meth) acrylic structure, a polyether structure, a poly (meth) acrylonitrile structure, a polyester structure, a polyalkylene structure, a polyamide structure, a polyimide structure, and a polyurethane. It has at least one selected from the group consisting of structures.
The recording medium liquid according to any one of 3 above.