JPH09124984A - Water-based ink for ink jet recording and ink jet recording method and equipment using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a water-based ink for ink jet recording which can eliminate creation of feathering and bleeding due to color-to-color intermixing of recorded images and realizes high color development by incorporating a polymer having a thermally reversible thickening property and a compd. having photothermal conversion capability into an aq. ink for ink jet recording. SOLUTION: A polymer having a thermally reversible thickening property in an amt. of 0.05 to 20wt.% and a compd. having photothermal conversion capability (a photosensitizing dye) are incorporated into an ink comprising a colorant and a color medium. Application of light hν to a photosensitizing dye (b) bonded to a polymer chain a showing a thermally reversible thickening property causes the photosensitizing dye to absorb hν and to give heat to the polymer chain. The polymer chain initiates thickening and incorporates the colorant C therein to provide a concentrated, high-viscosity solution. One preferred example of the polymer having a thermally reversible thickening property is a water-soluble polymer having a clouding point and/or a vinyl carboxylic acid ester of an alkylene oxide adduct of an active hydrogen compd. having a nitrogen-contg. ring in an amt. of 50wt.% or more as a constituent unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based ink jet recording method in which ink is ejected and ejected as small droplets from an ejection port (orifice), and the small droplets are adhered to the surface of a recording material for recording. INK, INKJET RECORDING METHOD USING THE SAME, EQUIPMENT USING THE INK, AND INKJET INK WHICH CAN REMOVE BLOODING (FEATHERING) AND BLOOD MIXING (BREADING) AND FORM A HIGH COLOR IMAGE, AND THE SAME And an apparatus using such an ink. Further, according to the present invention, the additional mechanism necessary for improving the recording performance of the device is simplified, the cost increase is effectively suppressed, and at the same time, energy saving can be achieved.

[0002]

2. Description of the Related Art Conventionally, water-based inks have been mainly used as ink jet recording inks from the viewpoints of safety and odor, and various water-soluble dyes or pigments have been used as coloring materials. There is known an ink in which a humectant, a dye dissolution aid, a fungicide, etc. are dissolved or dispersed in a liquid medium composed of a solvent and added as necessary. Ink jet recording using such an ink can discharge several thousand drops or more of ink per second, and high-speed recording is easy, noise is small, colorization is easy, and high resolution is possible. It has many advantages such as the ability to record on plain paper, and has been remarkably popular for several years.

Furthermore, in recent years, the price and performance of personal computers have increased,
Due to the standardization of the GUI environment, demands for high color development, high quality, high robustness, high resolution recording and high speed recording are increasing even in image recording by printers, etc. Various technical ideas are being proposed to leave the image on the surface of the paper as much as possible, increase the image density, sharpen the edges of the recording dots, and reduce bleeding (feathering) and color mixture bleeding.

A first example is disclosed in Japanese Patent Application Laid-Open No. 58-136.
No. 75, a method of adding polyvinylpyrrolidone to an ink to control the absorption and spread of recording dots on paper, and a second example, Japanese Patent Laid-Open No. 3-172362, discloses a specific microemulsion. Is added to the ink to control the absorption of the ink and the spread of the dots.

Further, as a third example in which the sol-gel transition phenomenon is applied to an ink, JP-A-62-181372 and JP-A-1-272623 disclose sol by heating in a gel state at room temperature. It describes that the ink which becomes a state is recorded on the recording material in a sol state and returns to a gel state by cooling the ink, so that the permeation of the ink into the paper can be suppressed. .

Recently, as a fourth example, Japanese Patent Laid-Open No. 6-49 has been proposed.
JP-A 399 discloses that an ink having a compound having a reversible thermal gelation property is added to an ink, good color developability, fixability and bleeding are small, and a printed matter is excellent in storage stability and reliability. Ink jet recording methods and devices using ink are disclosed. This technical background is based on the phenomenon that when an aqueous solution of a specific water-soluble polymer is heated, the water solubility decreases and the solution becomes cloudy (this temperature is called a cloud point).

Typical examples of the water-soluble polymer are N-isopropylacrylamide, polyvinyl methyl ether, polyethylene oxide, hydroxypropyl cellulose and the like. Since the solubility of these polymers has a negative temperature coefficient, they become separated and precipitated from the solution above the cloud point. In the deposited state, a hydrophobic microgel is generated and the viscosity of the solution is reduced. When recording is performed on the recording material in the deposited state, the original viscosity is restored by the temperature drop on the surface of the recording material, that is, the viscosity is increased and the permeation of the ink can be suppressed.

On the other hand, as a fifth example, M. Crouch
er et al. pointed out the problems of the conventional homogeneous ink, and proposed a heterogeneous ink using latex as a future inkjet ink (MDCrou
cher and MLHair; Ind.Eng.Chem.Res.1989,28,1712-17
18, "Design Criteria and Future Directions in Inkj
et Ink Technology ").

Further, US Pat. No. 4,246,154 discloses an ink in which fine particles of a dye-colored vinyl polymer are anionically stabilized. U.S. Pat. No. 4,680,332 discloses a heterogeneous ink in which a water-insoluble polymer containing an oil-soluble dye and having a nonionic stabilizer bound thereto is dispersed in a liquid medium. Also, US Pat. No. 5,100,471 proposes an aqueous ink comprising a solvent and colored particles comprising a silica shell in which a polymer core and a dye are covalently bonded, and a clearer color on paper is obtained. It is described that it has characteristics such as being formed, being stable against temperature change, and obtaining an image having high water resistance.

On the other hand, as a sixth example, JP-A-3-240586 proposes to use, as a non-aqueous ink, colored particles coated with a resin swelling in a dispersion medium and dispersed in kerosene or the like. There is. This proposal states that it is particularly effective in preventing image bleeding and preventing clogging of the droplet discharge nozzles.

As a seventh example, as means for enabling high-quality recording without blurring on general-purpose recording paper regardless of paper quality, Japanese Patent Laid-Open No. 63-87279 discloses a recording medium attached to the recording medium. To a temperature higher than room temperature (80 to 14
There is disclosed an inkjet recording method in which the physical properties of a combination of a recording paper and ink are heated to 0 ° C.) so that the physical properties have predetermined values.

[0012]

However, in the first and second examples of the conventional example described above, since the permeation into the paper is suppressed, the ink remains on the paper for a long time without being permeated. , There is a problem with the ink fixability. There is also a problem that color mixing (bleeding) between different colors occurs. The sol-gel transition ink of the third example may have fluidity due to a change in the storage temperature of the printed matter, and there is a problem of color mixing stains and transfer stains due to the flow of the image.

In the ink containing the reversible thermogelling compound of the fourth example, since water-soluble cellulose ethers are used,
The increase in viscosity due to the temperature decrease is slow, and it is not suitable for a method of recording one pixel at a high speed of several tens of msec or less like inkjet recording. Further, when used for ink jet recording, the upper limit of the viscosity at the time of ink ejection is as low as 20 mPa · s or less, so that it must be used at a low concentration and it is difficult to obtain a sufficient thickening effect.

On the other hand, among the fifth example group, the one in which the coloring material is anionically stabilized has a problem that the pH range in which the coloring material is stably dispersed is narrow and the selection range of the dye is small.
Further, there is a drawback that the spread of the recording dots on the paper is small and it is difficult to obtain the required optical density (OD). Also, in terms of shortening the fixing time required for high-speed recording, as in the case of the conventional image forming means, the fixing of ink depends only on evaporation and permeation, so that the effect is small.

In another example of a dispersion ink of a polymer containing an oil-soluble dye and having a nonionic stabilizer bound thereto, although the selection range of the dye is widened, the fixing mechanism is dependent on evaporation and penetration similarly to the above. Therefore, the effect of shortening the ink fixing time is small. In addition, color mixing (bleeding) between different colors is also disadvantageous because it takes time to fix between adjacent dots.

Further, the dispersion ink having the polymer core / silica shell structure is excellent in the dispersion stability of the pigment, but since it does not have a special means for aggregating the coloring material on the paper surface, the O.V. D. Is not enough. Further, since fixing of ink depends on evaporation and penetration, there is little effect in shortening the fixing time, and there is a problem of bleeding.

Further, as a problem common to the above-mentioned three examples, since the adherence of the coloring material particles to the paper surface is not taken into consideration, the rubbing property of the recorded image is poor. Further, in the sixth conventional example, since kerosene is used as the dispersion medium, there are problems with odor and safety.

Further, in the seventh example, the surface temperature of the paper is 80
Recording is performed by heating the temperature above ℃ and utilizing the change in physical properties due to the heat of the ink adhering to the paper. Since the temperature rise of the ink is due to the secondary heating from the paper, it is necessary to raise the temperature. There is a problem that the amount of heat is as large as 1 cal / g · ° C. or more and the efficiency is low. Further, heating at 100 ° C. or higher requires a passage for discharging generated steam, which is a disadvantage that the device becomes large. Further, there is a problem that evaporation of water in the ink in the nozzles of the recording head caused by radiant heat from the heated paper, and further, deterioration of ejection property of the recording head due to thickening.

A surface tension of 2 is a physical property required for jetting small droplets as an aqueous ink, particularly an ink jet ink.
It is smaller than 0 dyne / cm (related to the refill speed), the viscosity is in the range of 1 to 20 mPa · s, the pH value is about 3 to 10, and the fixing time of the ink is 20 s.
It is faster than ec (better as short as possible).

Here, the transfer of ink to paper will be considered. In general, regarding the transfer phenomenon of liquid to paper, Luca
The equation of s-Washburn is known, and when the liquid transfer amount is V, the paper roughness index is Vr, the absorption coefficient is Ka, the transfer time is T, and the wetting start time is Tw. , The transfer amount V of the liquid is represented by the following formula (1).

(Equation 1) Further, Ka in the above formula (1) relates to physical properties of both paper and ink and is represented by the following formula (2).

(Equation 2) However, in the equation (2), r is the capillary radius of the paper, γ is the surface tension of the liquid, θ is the contact angle, and η is the viscosity of the liquid.

From the above formula (1), it is found that in order to leave the coloring material on the surface of the paper, it is necessary to slow the permeation of the liquid as much as possible, that is, to reduce the value of Ka (Ka should be small. You can save time by evaporation). As for the physical properties of the ink for that purpose, it can be seen from the formula (2) that the surface tension γ is small, the viscosity η is large, and the contact angle θ is large. However, as described above, there are various restrictions on the physical properties of ink jet inks, so Ka
Adjustment is not easy.

On the other hand, if the liquid is a non-aqueous solvent such as ethanol, the wetting time Tw in the formula (1) can be ignored, so that the fixing can be accelerated.
Since the Ka value also increases and the effect of permeation increases, "feathering" increases as an image. Furthermore,
In the formula (2), the term of cos θ is determined by the combination of ink and paper, so that it may be good or bad depending on the type of paper. That is, the paper selectivity cannot be satisfied. It is considered that the problems described above can occur even in the conventional color material-dispersed ink as long as image formation depends on permeation and evaporation.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, in particular, to eliminate bleeding (feathering) and color mixture bleeding, and to form a highly colored image. It is an object of the present invention to provide an inkjet recording method using the same and devices using the ink.

[0024]

The above object is achieved by the present invention described below. That is, the present invention provides an ink composed of a liquid composition containing a coloring material and a liquid medium, showing a polymer exhibiting a thermoreversible thickening property in the ink and a compound having a photothermal conversion function or a thermoreversible thickening property. Further, the present invention relates to a water-based ink for inkjet, which contains a polymer having a photothermal conversion portion, an inkjet recording method using the same, and devices using the ink.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors believe that the above-mentioned restrictions in the prior art are due to the fact that the ink is a liquid in which the coloring material and the solvent are always uniform regardless of the temperature. Thinking, the temperature triggers the ink to change state,
An ink having the above-mentioned constitution, which thickens above a certain temperature on a recording material, was devised.

That is, the state change in this case means that a polymer, which has a low viscosity and is uniformly dissolved and dissociated in an ink state at room temperature, has an ink temperature higher than a certain temperature (hereinafter, this temperature is referred to as a transition temperature). When the temperature rises, the polymers are associated with each other to form a thick and highly viscous liquid, and the coloring material is in a state of being bonded to the polymer.
When recording is performed on the recording material in that state, the rich color material phase remains on the surface of the recording material, and the dilute solvent phase permeates into the recording material. Such a change in the state of the ink may occur due to heating of the ink from the outside, but the inventors of the present invention further conducted extensive studies to minimize the energy required for heating the ink, and as a result, only the polymer was found. We have succeeded in devising and putting into practical use a mechanism in which the state changes with temperature, leading to the present invention.

The mechanism by which only the polymer changes state with temperature will be described in detail below. The ink is made to coexist with a polymer that thermally reversibly thickens and a compound that absorbs light and converts it into heat, or a part of the polymer that thermally reversibly thickens light. By introducing a portion that absorbs and converts into heat, when irradiated with visible light or the like, energy due to light irradiation such as visible light is absorbed in the light-heat conversion part, and heat is generated in the vicinity of the polymer. When the above occurs, the association of macromolecules is induced, and the above-mentioned effect is exhibited. The polymer used here is preferably one that coordinates a dye molecule, and a better effect can be obtained by having active oxygen in the molecule. As the light-heat conversion part, a photosensitizing dye is effective, and a dye having a porphyrin ring is particularly suitable.

FIG. 1 shows a conceptual diagram of a polymer having the above-mentioned function which is contained in the ink of the present invention. In the figure, a is a polymer chain exhibiting thermoreversible viscosity increase, and b is a photosensitizing dye bonded to one end of the polymer chain a. Now 500n
When irradiated with m visible light, the photosensitizing dye absorbs the light energy hν and gives heat Δ to the polymer chain. Then, the polymer chains start to thicken due to the heat Δ, and are associated with each other while incorporating the coloring material c into the inside to form a thick high-viscosity liquid, and the above-mentioned effect is obtained.

Next, the present invention will be described in more detail with reference to preferred embodiments. First, the thermoreversible thickening polymer used in the ink of the present invention, which dissociates, dissolves, and associates and thickens at a certain transition temperature, will be described. The thermoreversible thickening polymer is a polymer whose aqueous solution, water suspension or the like thickens at a certain temperature (transition temperature) or more and has a reversible temperature-viscosity relationship.

A preferred specific example of the above-mentioned polymer used in the present invention is a vinyl carboxylic acid ester (a) of an alkylene oxide adduct of an active hydrogen compound having a nitrogen-containing ring.
Is a water-soluble vinyl polymer (A) containing 50% by weight or more as a structural unit, and the compound (a) further comprises
Examples thereof include compounds that are (meth) acrylic acid esters of 1 to 20 mol adducts of (substituted) morpholine with ethylene oxide and / or propylene oxide.

The active hydrogen compound having a nitrogen-containing ring is a compound having active hydrogen for addition of a nitrogen-containing ring and an alkylene oxide, and specifically, a nitrogen-containing alicyclic compound, for example, an aziridine ring. Having (pyrrolidine, 2-methylaziridine, etc.), those having a pyrrolidine ring (pyrrolidine, 2-methylpyrrolidine,
2-pyrrolidone, succinimide, etc.), those having a piperidine ring (piperidine, 2-methylpiperidine, 3,
5-dimethylpiperidine, 2-ethylpiperidine, 4-
Piperidinopiperidine, 4-pyrrolidinopiperidine, ethyl pipecolate, etc.), those having a piperazine ring (1-methylpiperazine, 1-methyl-3-ethylpiperazine, etc.), those having a morpholine ring (morpholine,
2-methylmorpholine, 3,5-dimethylmorpholine, etc.) and ε-caprolactam, nitrogen-containing unsaturated cyclic compounds (3-pyrroline, 2,5-dimethyl-3-pyrroline,
2-hydroxypyridine, 4-pyridylcarbinol,
2-hydroxypyrimidine) and the like.

Of these, preferred are nitrogen-containing alicyclic compounds, more preferred are those having a piperidine ring and those having a morpholine ring, and most preferred are those having a morpholine ring.

Further, as the alkylene oxide in the present invention, ethylene oxide, propylene oxide and butylene oxide are preferable. The transition temperature of the thermoreversible thickening polymer in the present invention can be easily adjusted by adjusting the types of these alkylene oxides and the number of addition moles thereof. For example, in the case of ethylene oxide, the addition mole If the number is large, the transition temperature rises, and in the case of propylene oxide or butylene oxide, the transition temperature becomes low due to the increase in the number of addition moles. The number of moles of alkylene oxide added is preferably about 1 to 20 moles, and more preferably 1 to 5 moles.

The vinyl carboxylic acid ester (a) of an alkylene oxide adduct of an active hydrogen compound having a nitrogen-containing ring is an ester of an alkylene oxide adduct and a vinyl carboxylic acid as described above. As the acid, (meth) acrylic acid, acrylic acid, maleic acid, vinyl benzoic acid and derivatives thereof are preferable, and (meth) acrylic acid and (meth) acrylic acid derivatives are particularly preferable.

Further, as the water-soluble vinyl-based polymer (A) in the present invention, one or more kinds of the above-mentioned ester (a), or one or more kinds of the ester (a) and another vinyl-based monomer (b) are used. )), And may contain at least 50% by weight of the ester (a) as a constituent unit. Examples of the other vinyl polymer (b) used in this case include hydroxyethyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, (meth) acrylamide, N-
Hydroxymethyl (meth) acrylamide, N-vinyl-2-pyrrolidone, (meth) acrylic acid, (anhydrous) maleic acid, styrenesulfonic acid, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminopropyl ( (Meth) acrylate, methyl (meth) acrylate, butyl (meth) acrylate, glycidyl (meth) acrylate, N-butyl (meth) acrylamide, N-cyclohexyl (meth) acrylamide, (meth) acrylonitrile, styrene, vinyl acetate, vinyl chloride , Butadiene, isoprene and the like are preferable.

Among the monomers constituting the water-soluble vinyl polymer (A), the temperature range of thickening varies depending on the composition ratio of the ester (a), but in order to make the temperature range as small as possible, the ester is used. The content of (a) as a constituent unit is preferably 50% by weight or more, more preferably 70% by weight or more.

Another example of the thermoreversible thickening polymer used in the present invention is a vinylcarboxylic acid ester monomer (a) of an alkylene oxide adduct of an active hydrogen compound having a nitrogen-containing ring. There is a polymer obtained by copolymerizing a monomer composition containing one or more kinds and one or more kinds of monomers represented by the following general formula (I) in a total amount of 50% by weight or more.

[0038]

Embedded image (However, in the general formula (I), R ₁ is H or C
H ₃ and R ₂ represent H or an alkyl group having 1 to 30 carbon atoms, a (alkyl) phenyl group or a (alkyl-substituted) aminoalkyl group, n is 2 to 4, m is 2 to 4 and l is 2 to 4 ,
x is 2 to 50, y is 0 or 1 to 50, z is 0 or 1 to 5.
Each represents an integer of 0, except that n, m and l are the same number, and n and m or m and l are the same number. )

As the monomer (I), a vinyl type (meth) is used.
It has a structure in which an alkylene oxide is added to an acrylic acid monomer, and specifically, ω-methoxy polyethylene glycol monoacrylate, ω-methoxy polyethylene glycol monomethacrylate, ω-ethoxy polyethylene glycol monoacrylate, ω-ethoxy polyethylene glycol monoacrylate. Methacrylate, ω-n-propyl polyethylene glycol monoacrylate, ω-
n-propyl polyethylene glycol monomethacrylate, ω-iso-propyl polyethylene glycol monoacrylate, ω-iso-propyl polyethylene glycol monomethacrylate, ω-n-butyl polyethylene glycol monoacrylate, ω-n-butyl polyethylene glycol monomethacrylate, ω- iso-butyl polyethylene glycol monoacrylate, ω-i
So-butyl polyethylene glycol monomethacrylate, ω-tert-butyl polyethylene glycol monoacrylate, ω-tert-butyl polyethylene glycol methacrylate, ω-phenoxy polyethylene glycol monoacrylate, ω-phenoxy polyethylene glycol monomethacrylate, (poly) propylene glycol-polyethylene Glycol monoacrylate, (poly) propylene glycol-polyethylene glycol monomethacrylate, ω-methoxy (poly) propylene glycol-polyethylene glycol monoacrylate, ω-methoxy (poly) propylene glycol-
Polyethylene glycol monomethacrylate, (poly)
Butylene glycol-polyethylene glycol monoacrylate, (poly) butylene glycol-polyethylene glycol monomethacrylate, ω-methoxy (poly)
Butylene glycol-polyethylene glycol monoacrylate, ω-methoxy (poly) butylene glycol-
Polyethylene glycol monomethacrylate, ω-methoxy (poly) ethylene glycol- (poly) propylene glycol-polyethylene glycol monoacrylate, ω-methoxy (poly) ethylene glycol- (poly) propylene glycol-polyethylene glycol monomethacrylate, ω-hexyloxy polyethylene Glycol mono (meth) acrylate, octadecyloxy polyethylene glycol mono (meth) acrylate,
ω-octylphenyl (poly) ethylene glycol-polypropylene glycol mono (meth) acrylate, nonylphenyloxy (poly) ethylene glycol- (poly) propylene glycol-polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, ω -Methoxypolybutylene glycol mono (meth) acrylate, ω-methoxypolytetramethylene glycol mono (meth) acrylate,
ω-dimethylaminoethyl polyethylene glycol mono (meth) acrylate and the like can be mentioned.

As a method for synthesizing the above-mentioned monomer, for example,
In the presence of an alkali metal catalyst (sodium hydroxide, potassium hydroxide, etc.) on methacrylic acid or acrylic acid, 5
A method of sequentially adding alkylene oxide (ethylene oxide, propylene oxide, butylene oxide) at 0 to 200 ° C. and 1 to 10 atm, in the presence of an alkali metal catalyst to an alcohol or phenol having 1 to 4 carbon atoms, 5
Polyether monool obtained by sequentially adding alkylene oxide (ethylene oxide, propylene oxide, butylene oxide) at 0 to 200 ° C. and 1 to 10 atm and methacrylic acid or acrylic acid are mixed with an acidic catalyst (sulfuric acid, paratoluene sulfone). Acid, etc.) in the presence of 50 to 20
Esterification at 0 ° C., 1 to 10 atm, or with an esterification reagent (dicyclohexylcarbodiimide, etc.),
Examples thereof include a method of reacting at −10 to 50 ° C. and normal pressure.

Further, although the effect is similar to that of the above-mentioned polymer, a water-soluble polymer having a cloud point can be used in the present invention. A water-soluble polymer having a cloud point indicates a phenomenon in which the water solubility decreases and the solution becomes cloudy when the aqueous solution is heated (the temperature at that time is called a cloud point). For example, N-alkyl substitution Vinyl-based polymers are mentioned as typical ones (Reference: Hiroshi Ito, Atsuhiko Nitta; “Thermosetting Resin”, Vol. 7, No. 2, 14).
(1986)). In the present invention, the temperature at which the aqueous polymer solution changes its state is defined as “transition temperature”, and this transition temperature does not require that the aqueous solution becomes cloudy.

Specific examples of the water-soluble polymer having the above cloud point include N-ethylacrylamide, N-cyclopropyl (meth) acrylamide, N-isopropyl (meth) acrylamide and Nn-propyl (meth). Acrylamide, N-tetrahydrofurylacrylamide, N
-Acroylpyrrolidine, N-Acroylpiperidine,
N-2-Ethoxyethyl (meth) acrylamide, N-
3-methoxypropyl (meth) acrylamide, N-3
-Ethoxypropyl (meth) acrylamide, N-3-
Isopropoxypropyl (meth) acrylamide, N-
3- (2-methoxyethoxy) propyl (meth) acrylamide, N-1-methyl-2-methoxyethyl (meth) acrylamide, N-1-methoxymethylpropyl (meth) acrylamide, N-methyl-N-ethylacrylamide, N-methyl-N-isopropylacrylamide, N-methyl-Nn-propylacrylamide,
N, N-diethylacrylamide, N- (2,2-dimethoxyethyl) -N-methylacrylamide, N-
(1,3-Dioxolan-2-ylmethyl) -N-methylacrylamide, N-8-acroyl-1,4-dioxa-8-azaspiro [4,5] decane, N-2-methoxyethyl-N-ethylacrylamide , N-2-methoxyethyl-Nn-propylacrylamide, N-2
-Methoxyethyl-N-isopropylacrylamide,
Examples thereof include polymers of N, N-Bis (2-methoxyethyl) acrylamide and methyl vinyl ether, 2- (2-methoxyethoxy) ethyl vinyl ether, 2-methyl-5-vinylpyridine, N-vinylpyrrolidone, ethylene oxide and the like. However, the transition temperature is the salt in the ink,
Since it changes depending on the type and amount of the additive components such as the surfactant and the solvent, it is necessary to use the transition temperature in the applied ink composition.

Next, the compound having a light-heat converting function (called a light-heat converting compound) used in the present invention will be described. The photothermal conversion compound is a series of compounds having the ability to convert the absorbed light energy into heat and transmit it to a substrate or the like. Generally, indigo-based photosensitizing dyes, porphyrin-based photosensitizing dyes, xanthene-based photosensitizing dyes, thiazine-based photosensitizing dyes, chlorophyll-based photosensitizing dyes, and quinone-based photosensitizing dyes, which are generally called energy conversion dyes. Examples include sensitizing dyes. Among these, porphyrin-based and chlorophyll-based dyes have absorption wavelengths in the visible region, and have an argon laser (wavelength 48 nm).
(8 nm), halogen lamps, fluorescent lamps, xenon lamps and other primary light sources can be used for photothermal conversion. The structures of the photosensitizing dye having a porphyrin ring and copper chlorophyll sodium salt are shown below.

[0044]

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[0045]

[Chemical 6]

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The thermoreversible thickening polymer and the photothermal conversion compound described above are each made into an aqueous solution, and both are mixed,
By irradiating the aqueous solution with light, the polymer exhibits thermoreversible viscosity increase due to the heat generated by the photothermal conversion compound.
More preferably, when the polymer and the photosensitizing dye are bound to each other, the heat generated by the photothermal conversion is efficiently transferred to the polymer chains in a very close distance, so that the light energy to be irradiated may be small. , Further benefits can be obtained. The amount of heat required to change the state of the polymer is estimated to be about 0.1 cal / g in a 1% polymer aqueous solution (Reference: M.
Henskins, JEGuillet; J.Macromol.Sci.Chem.A2,144
(1968)), on the other hand, when the state changes due to heating from the outside, for example, about 30 cal /
Since the heat quantity of g is required, the photothermal conversion method of the present invention is considered to be very energy efficient.

Next, the coloring material used in the ink of the present invention will be described. Examples of the coloring material that can be used in the present invention include dyes, carbon black or organic pigments, coloring material fine particles in which the dye is water-insoluble by binding the dye to the surface of the fine particles, and a core / shell having a reactive group on the surface of the shell. Examples include coloring material fine particles in which a dye is chemically bonded to organic fine particles having a structure.

First, the dye that can be used as a coloring material in the present invention is one that interacts with the thermoreversible thickening polymer used in the present invention and promotes association of polymer chains at a transition temperature or higher. For example, direct dye, acid dye,
Examples include food dyes, basic dyes, reactive dyes, and the like. These most hydrophobic dye skeleton and several sulfonate (-SO ₃ M), carboxylates (-COOM), ammonium salts (NH ₄ X) solubilizing groups and hydrogen-bonding hydroxyl group, such as ( -OH), amino group (-NH _2), imino group (-
NH-) and the like, and can form a complex with the thermoreversible thickening polymer used in the present invention. The disperse dye itself is water-insoluble, but since the disperse dye is used in combination with a polycyclic anion activator such as naphthalene sulfonate as a dispersant, the apparent ionicity of the dye is the same as that of the direct dye. Can be used as well.

Specific examples of the above dye include CIDirect B
lack 17, CIDirect Black 19, CIDirect Blac
k 62, CIDirect Black 154, CIFood Black
2, CIReactive Black 5, CIAcid Black 52, I.
CIProjet Fast Black 2 and other black dyes, CIDire
ct Yellow 11, CIDirect Yellow 44, CIDirect
Yellow 86, CIDirect Yellow 142, CIDirect
Yellow 330, CIAcid Yellow 3, CIAcid Yello
w 38, CIBasic Yellow 11, CIBasic Yellow 5
1, CIDisperse Yellow 3, CIDisperse Yellow
5, yellow dyes such as CI Reactive Yellow 2, CIDi
rect Red 227, CIDirect Red 23, CIAcid Red
18, CIAcidRed 52, CIBasic Red 14, CIB
Magenta dyes such as asic Red 39, CIDisperse Red 60, CIDirect Blue 15, CIDirect Blue 199,
CIDirect Blue 168, CIAcid Blue 9, CIAcid
Blue 40, CIBasic Blue 41, CIAcid Blue7
4. Cyan dyes such as CI Reactive Blue 15 can be mentioned.

Other than these dyes, those having reduced water-solubilizing groups to increase water resistance, those having special pH-sensitive solubility, and the like can be used in the present invention.
The concentration of the dye in the ink can be freely selected within the range of solubility, and usually 1 to 8% by weight is preferable,
3 to 10% by weight for recording on cloth, metal (alumite), etc.
Is preferable, and 0.0 when the recorded image requires light and shade.
1-10% by weight is preferred.

Next, carbon black and organic pigments can be used as the second coloring material. These coloring materials are capable of interacting with the polymer compound of the present invention through the dispersant, because the dispersant is used together with the disperse dye. Any of these pigments can be used as long as they are suitable for ink jet recording. Among them, the carbon black used for the black ink is one produced by the furnace method or the channel method and has a primary particle size of Is 10
-40 mμ, BET specific surface area 50-300 m
² / g, DBP oil absorption of 40 to 150 m1 / 100 g is desirable.

Examples of carbon black include, for example:
No. manufactured by Mitsubishi Chemical 2300, No. 900, MCF8
8, No. 33, no. 40, No. 45, no. 5
2, MA7, MA8, # 2200B, Raven 1255, Raven 1060 manufactured by Colombia Carbon, Rega1 330R, Rege1 660R manufactured by Cabot, Mogul L, DE.
GUSSA Color Black FW 18, Printex 35, Prin
tex U, etc., such as those obtained by subjecting the surface of these carbon blacks to an oxidation treatment or a plasma treatment, in addition, insoluble azo pigments, soluble azo pigments, phthalocyanine-based pigments, isoindolinone-based higher pigments, quinacridone-based higher pigments,
Organic pigments such as dioxane violet and perinone / perylene high-grade pigments can be used. Further, as a coloring material classified into the above-mentioned pigments, a so-called dye lake in which a dye is dyed with an extender pigment can also be used as the coloring material of the present invention.

Further, as the third coloring material that can be used in the present invention, there can be mentioned coloring material fine particles in which a dye is bound to the surface of the fine particles to render the dye water-insoluble. The coloring material fine particles described here are core / reactive groups having reactive groups on the surface of the shell.
A dye is chemically bonded to organic fine particles having a shell structure, and the reactive group is preferably selected from a carboxyl group, a hydroxyl group, an amino group, an epoxide group, an amide group, a hydroxymethyl group and an isocyanate group. There are things.

The core portion of the core / shell type fine particles is
A styrene-divinylbenzene-based polymer having a high degree of cross-linking, which has the above-mentioned reactive group introduced on its surface is used. The thickness of the shell is preferably about 30% of the particle diameter so that the dye can be sufficiently dyed. Specifically, a fine particle dispersion S2467 made by Japan Synthetic Rubber is suitable.
To use as a coloring material, the property of S2467 is 10
nm to 80 nm and solid content of 10% by weight are selected.
The fine particle shell whose surface is modified with an amino group can form an ionic bond with an anionic dye ion like a direct dye, and can be easily dyed with a dye.
Further, by modifying the fine particle shell with a carboxyl group, an ionic bond is formed with a dye having a cationic dye ion such as a basic dye, and the shell can be dyed.

The colored fine particles after dyeing can be used as a coloring material for the ink of the present invention by treating them in the same manner as the above-mentioned pigment, and the viscosity of the fine particles can be increased in the same manner as when the fine particle dispersion is added. The effect is improved. Further, the water resistance is improved as compared with the case where only the dye is used, and the fastness of the recorded image can be increased. The three kinds of coloring materials described above may be used individually, but the coloring material fine particles and the dye are mixed or used, or the coloring material fine particles and the carbon black or the organic pigment are mixed. Needless to say, when it is used, it is advantageous for further improving the quality of a recorded image, such as high color development due to an increase in thickening effect and sharper edges of recording dots due to inclusion of particles.

The ink of the present invention containing a thermoreversible thickening polymer and a coloring material as described above in a liquid medium is more suitable for ink jetting such as reliability, storage stability or adjustment of ink permeability. In order to apply, a moisturizer or a dissolution aid as described below may be contained. Such materials include 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2 , 3-butanediol, 1,5-pentanediol, 1,7-heptanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, glycerin, diethylene glycol, triethylene glycol,
Tetraethylene glycol, polyethylene glycol 2
00, dipropylene glycol, 2,2'-thiodiethanol, alkylene glycols such as 1,2,6-hexanetriol, alcohol amines such as monoethanolamine, diethanolamine and triethanolamine, dimethylformamide, dimethylacetamide and dimethyl. Aprotic polar solvents such as sulfoxide, sulfolane, and 1,3-propanesulfone, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-dibutoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di Butyl ether, 2-methoxyethanol, 2
-Ethoxyethanol, 2- (methoxymethoxy) ethanol, 2-butoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ethyl ether, 1-methoxy-2-propanol, 1-ethoxy-
Lower alkyl ethers of polyhydric alcohols such as 2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether and tripropylene glycol monomethyl ether; formamide, 2-pyrrolidone, N-methyl-2-pyrrolidone , 1,3-dimethylimidazolidinone, sorbit, urea and 1,3-bis (β-hydroxyethyl) urea. The content of these inks is preferably in the range of 1 to 30% of the total weight of the ink.

Further, when the ink of the present invention is used for ink jet recording, when an alkyl alcohol such as methanol, ethanol, propanol, 2-propanol, 1-butanol or 2-butanol is contained, the jettability is further improved. It is effective. These alcohols are preferably contained in the range of 1 to 10% by weight based on the total weight of the ink. Further, if necessary, the ink of the present invention may contain additives such as a surfactant, a rust preventive, a fungicide, an antioxidant and a pH adjuster.

As described above, the ink of the present invention is effective when used in ink jet recording. As the inkjet recording method, there are a recording method in which mechanical energy is applied to ink to eject a droplet, and a recording method in which thermal energy is applied to the ink to eject a droplet by bubbling of the ink. The ink of the present invention is particularly suitable.

First, as an ink jet recording apparatus, an example of a head structure which is a main part of an apparatus utilizing heat energy is shown in FIGS. 2, 3 and 4. The head 1 is obtained by adhering a glass, ceramic, silicon or plastic plate or the like having a flow path (nozzle) 2 through which ink and a heating element substrate 3 to each other. The heating element substrate 3 includes a protective layer 4 formed of silicon oxide, silicon nitride, silicon carbide or the like, an electrode 5 formed of aluminum, gold, aluminum-copper alloy or the like, a high melting point material such as HfB ₂ , TaN and TaAl. A heat generating resistor layer 6 formed of, a heat storage layer 7 formed of thermally oxidized silicon, aluminum oxide or the like, and silicon,
The substrate 8 is made of a material having a good heat dissipation property such as aluminum and aluminum nitride. Incidentally, 102
Is an optical waveguide, and 103 is a light irradiation lens. here,
Although an example in which the head is provided with a light irradiation mechanism has been shown, the present invention is not limited to this. For example, when a device provided with a light irradiation mechanism as shown in FIG. It is not necessary to provide an irradiation mechanism.

When a pulsed electric signal is applied to the electrode 5 of the head 1, the area indicated by h on the heating element substrate 3 rapidly generates heat, and bubbles are generated in the ink in contact with this surface. The pressure causes the meniscus 10 to project, and the ink is ejected through the nozzle 2 of the head to become a small ink droplet,
It flies from the discharge orifice 11 toward the recording material 13. FIG. 4 shows an external view of a multi-head in which a large number of the heads shown in FIG. 2 are arranged. 2 is a cross-sectional view of the head 1 along the ink flow path, and FIG. 3 is a cross-sectional view taken along line XY of FIG.

FIG. 5 shows an example of an ink jet recording apparatus incorporating the above head. In FIG. 5, reference numeral 61 denotes a blade as a wiping member, one end of which is held and fixed by a blade holding member, and forms a cantilever. The blade 61 is arranged at a position adjacent to a recording area of the recording head 65, and in the present example, is held in a form protruding into the movement path of the recording head 65. Reference numeral 62 denotes a cap of the ejection port surface of the recording head 65, which is arranged at a home position adjacent to the blade 61, moves in a direction perpendicular to the moving direction of the recording head 65, contacts the ejection port surface, and performs capping. Equipped with. Further, 63 is an ink absorber provided adjacent to the blade 61, like the blade 61.
5 is retained in a protruding form in the movement path of 5. The blade 61, the cap 62, and the ink absorber 63 constitute an ejection recovery unit 64, and the blade 61 and the ink absorber 63 remove water, dust, and the like from the ejection port surface.

Reference numeral 65 denotes a recording head having ejection energy generating means for ejecting ink to a recording material facing the ejection port surface where the ejection ports are arranged for recording, and 66 a recording head 65.
It is a carriage for mounting and moving. The carriage 66 is slidably engaged with the guide shaft 67, and a part of the carriage 66 is connected to a belt 69 driven by a motor 68 (not shown). As a result, the carriage 66 can move along the guide shaft 67, and the recording head 65 can move the recording area and the adjacent area. Reference numeral 51 is a paper feed section for inserting a recording material, and 52 is a paper feed roller driven by a motor (not shown). With these configurations, the recording material is fed to the position facing the ejection port surface of the recording head 65, and is ejected to the ejection section provided with the ejection roller 53 as the recording progresses.

In the above structure, when the recording head 65 returns to the home position after recording is completed, the cap 62 of the ejection recovery unit 64 is retracted from the movement path of the recording head 65, but the blade 61 projects into the movement path. There is. As a result, the ejection port of the recording head 65 is wiped.
When the cap 62 comes into contact with the ejection surface of the recording head 65 to perform capping, the cap 62 moves so as to project into the movement path of the recording head. Recording head 65
Is moving from the home position to the recording start position,
The cap 62 and the blade 61 are in the same position as the above-mentioned position at the time of wiping. As a result, the ejection port surface of the recording head 65 is also wiped during this movement.
To move the recording head 65 to the home position,
Not only at the end of recording and at the time of ejection recovery, but also at the recording head 65
Moves to the home position adjacent to the recording area at a predetermined interval while moving in the recording area for recording, and the wiping is performed in accordance with this movement.

FIG. 6 is a diagram showing an example of an ink cartridge 45 in which ink to be supplied to the recording head via an ink feeding member, for example, a tube. here,
Reference numeral 40 is an ink containing portion containing the ink for supply, for example,
It is an ink bag, and a rubber stopper 42 is provided at the tip thereof. By inserting a needle (not shown) into the stopper 42, the ink in the ink bag 40 can be supplied to the head. An ink absorber 44 receives the waste ink. It is preferable for the present invention that the surface of the ink containing portion which is in contact with the ink is made of polyolefin, especially polyethylene.

The ink jet recording apparatus used in the present invention is not limited to the one in which the head and the ink cartridge are separately provided as described above, but is also suitable for the one in which they are integrated as shown in FIG. Used. In FIG. 7, reference numeral 70 denotes a recording unit, in which an ink containing portion containing ink, for example, an ink absorber is contained, and the ink in the ink absorber has a head portion having a plurality of orifices. The ink is ejected from 71 as an ink droplet. As the material of the ink absorber,
The use of polyurethane is preferred for the present invention.
Further, a structure may be adopted in which the ink containing portion is an ink bag having a spring or the like provided therein, without using the ink absorber. Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the recording unit with the atmosphere. The recording unit 70 is used in place of the recording head shown in FIG. 4, and is detachable from the carriage 66.

Next, as a form of the second ink jet recording apparatus, a nozzle forming substrate having a plurality of nozzles, a pressure generating element made of a piezoelectric material and a conductive material and arranged to face the nozzles, and the pressure generating element. There is an on-demand inkjet recording head which is provided with ink that fills the surroundings of the above, and in which a pressure generating element is displaced by an applied voltage to eject small ink droplets from a nozzle. FIG. 8 shows a configuration example of a recording head which is a main part of the recording apparatus.
The head has an ink flow path 8 communicating with an ink chamber (not shown).
0, an orifice plate 81 for ejecting ink droplets of a desired volume, and a vibrating plate 8 for directly applying pressure to ink
2. Piezoelectric element 83 and piezoelectric element 83 joined to the vibration plate 82 and displaced by an electric signal, orifice plate 8
1 and a substrate 84 for supporting and fixing the diaphragm 82 and the like.

In FIG. 8, the ink flow path 80 is formed of photosensitive resin or the like, and the orifice plate 81 is formed with a discharge port 85 by electroforming or punching metal such as nickel or nickel by electroforming or vibration, and vibrates. Board 82
Is formed of a metal film of stainless steel, nickel, titanium, or the like, a high-elasticity resin film, or the like.
Is formed of a dielectric material such as barium titanate and PZT. The recording head having the above-described structure is provided with the piezoelectric element 83.
A pulsed voltage is applied to the piezoelectric element 83 to generate a strain stress, the energy of which deforms the vibrating plate 82 bonded to the piezoelectric element 83, and presses ink in the ink flow path vertically to eject ink droplets from the orifice plate 81. It operates so as to perform ejection and recording from the ejection port 85. The recording head is used by incorporating it in a recording device similar to that shown in FIG. The detailed operation of the recording device may be performed in the same manner as described above and may be performed.

Next, an example of a procedure for recording an image by irradiating the ink of the present invention with light will be described with reference to the drawings. FIG.
Reference numeral 0 is an example of an ink jet recording apparatus incorporating a light irradiation mechanism. In FIG. 10, reference numeral 100 denotes a light source (unit array) for performing light irradiation, and 101 denotes a light source monitor for detecting a light source output. When the recording device detects the image signal, the light source 100 is turned on, and a portion corresponding to the recording surface is previously irradiated with light with a predetermined light source output. Subsequently, when the light source monitor 101 detects that the light source output has reached the predetermined value, the recording material is conveyed to the recording position. here,
If the recording material does not exist at the position of the carriage guide shaft 67, the reliability of the apparatus is increased by providing a means for stopping the recording operation and making the operator aware of the error. Next, the inkjet recording head 91 on the carriage 66
Forms dots on the recording material according to the image signal. During this period, the light irradiation continuously irradiates the recording dots. The image signal is only 2 bytes of character data, or a photo,
If the light source output is varied depending on whether there is a large amount of bitmap signals as shown in the illustration, it is possible to always record with a constant quality, so higher quality recording is possible.

Then, by detecting the last bit data immediately before the image signals for one page are all recorded, the light source 100 is turned off, and the next recording standby state is set. In the case of continuous recording, that is, in the case of recording a plurality of the same images, or in the case of recording all of the images composed of a plurality of pages, output is performed without turning off the light source between pages. Controlling such as dropping to / 5 is effective for low power consumption and stabilization of light source output. Further, when recording continuously on continuous paper, it is preferable to record while keeping the light source output constant.

[0070]

Next, the present invention will be described specifically with reference to examples and comparative examples. The composition ratio in the text is% by weight unless otherwise specified. First, production of various inks of the present invention will be described. The polymers showing thermoreversible thickening used in this example are shown in Table 1.

[0071]

[Table 1] Table 1: Thermoreversible thickening polymer used in this example The numbers in parentheses in the table are copolymer compositions. *: Ethylene oxide addition mole number = 10, Propylene oxide addition mole number = 22 **: Ethylene oxide addition mole number = 9

Next, the thermoreversible thickening polymer having the photothermal conversion portion used in the examples will be described. Since the polymer used in the present invention is a vinyl polymer, it can be obtained by mixing a monomer component and a predetermined photosensitizing dye and radical-copolymerizing them. The polymerization method is not particularly limited, and solution polymerization, emulsion polymerization, suspension polymerization and the like can be used. An example of synthesis will be described below. After preparing an aqueous solution having a composition of 2-morpholinoethyl methacrylate 98 parts and methacrylic acid 2 parts as a monomer component and mixing 1.8 parts of copper chlorophyllin sodium (manufactured by Wako Pure Chemical Industries) as a photosensitizing dye, under a nitrogen atmosphere. , Ammonium persulfate as a polymerization initiator 2.
0 part was added and radical polymerization was carried out at 40 ° C. for 8 hours to obtain a target polymer. Table 2 shows thermoreversible thickening polymers having a photosensitizing dye.

[0073]

[Table 2] Table 2: Thermoreversible thickening polymer having a photosensitizing dye used in this example.

The procedure for preparing the ink is such that an appropriate density (5
(10 to 10%) of a polymer ion-exchange water aqueous solution showing thermoreversible thickening is prepared in advance and prepared by the method described below. Examples 1 to 14 and Comparative Examples 1 to 4 [1] First, the case where the coloring material is a dye will be described. Ion-exchanged water, a photosensitizing dye (except for the polymers shown in Table 2), a solvent, an aqueous dye solution and, if necessary, a surfactant were added to the aqueous polymer solution in this order with stirring, and the predetermined amount of each composition was added. Adjust to the concentration. After stirring for 3 hours, pore size 0.4
The black ink of Examples 1 to 11 of the present invention, the yellow ink of Example 12, the magenta ink of Example 13, and the cyan color ink of Example 14 were prepared by filtering through a 5 μm membrane filter. Table 3A shows the compositions of Examples 1 to 11 (black ink), and Table 3B shows the compositions of Examples 12 to 14 (color ink).

[0075]

[Table 3] Table 3A: Compositions of Examples 1 to 11 (black ink) (unit:%)

[0076]

[Table 4] Table 3B: Compositions of Examples 12 to 14 (color inks) (unit:%)

Further, as a comparative example, an ink having the same composition as in Example 1 was prepared except that the thermoreversible thickening polymer and the photosensitizing dye were not used, and the black ink of Comparative Example 1 was prepared. . Similarly, an ink having the same composition as in Examples 12, 13, and 14 was prepared except that the thermoreversible thickening polymer and the photosensitizing dye were not used, and the color inks of Comparative Examples 2, 3, and 4 were prepared. And The thermoreversible thickening polymer and the photosensitizing dye were replaced with ion-exchanged water.

Example 15, Comparative Example 5 [2] Next, an ink using a pigment as a second coloring material will be described. First, a pigment dispersion is prepared. (Preparation of pigment dispersion liquid) -Styrene-ethyl acrylate copolymer (acid value 150, molecular weight 5,000) 1.5 g-Monoethanolamine 1.0 g-Diethylene glycol 81.5 g-Ion-exchanged water 5.0 g Are mixed and heated to 70 ° C. on a water bath to completely dissolve the resin component. 10 g of carbon black (trade name: MCF88; manufactured by Mitsubishi Kasei Co., Ltd.) in this solution
Then, 1 g of 2-propanol was added, and after premixing for 30 minutes, dispersion treatment was performed. A sand grinder (manufactured by Igarashi Kikai Co., Ltd.) was used as a disperser, and zirconium beads (1 mmφ) were used as a grinding medium, and a grinding treatment was performed for 3 hours at a filling rate of 50 vol%. Further, centrifugation treatment (12,000 rpm, 20 minutes) was performed to remove coarse particles to obtain a dispersion liquid.

(Preparation of Ink) Next, an aqueous polymer solution and a photosensitizing dye were added to the above-mentioned dispersion liquid, each component was added so as to have the following composition, and the mixture was mixed for 2 hours to prepare the ink of Example 15. It was made. Pigment dispersion 30 wt% Polymer A (solid content concentration) 5 wt% N-methyl-2-pyrrolidone 15 wt% Copper chlorophyllin sodium 0.5 wt% Ethanol 2 wt% Ion-exchanged water 47. 5% by weight Further, as a comparative example, an ink having the same composition as in Example 15 was prepared except that the thermoreversible thickening polymer and the photosensitizing dye were not used, and the ink of Comparative Example 5 was obtained. The thermoreversible thickening polymer and the photosensitizing dye were replaced with ion-exchanged water.

Examples 16 to 17 and Comparative Examples 6 to 7 [3] Next, inks using the third color material fine particles (Examples 16 and 17) will be described. (Preparation of Fine Particle Liquid for Coloring Material) First, a fine particle dispersion liquid S2467N (solid content 8.0%, pH 8.
No. 0, particle diameter 18 nm) was heated to 60 ° C., and an aqueous dye solution (CI Direct Black 1) was added thereto.
(9: 10%) dropwise with stirring, and finally mixed so that the volume ratio of the S2467N liquid and the dye aqueous solution becomes 3: 1, and further stirred for 8 hours. Then, it was filtered through a membrane filter having a pore size of 0.45 μm to obtain a coloring material fine particle liquid.

(Preparation of Ink) Next, an aqueous polymer solution, a solvent and the like were added to the coloring material fine particle liquid obtained above, and the respective components were mixed so as to have the following composition, whereby an ink of Example 16 was obtained. .・ Color material fine particle liquid 70% by weight ・ Polymer A (solid content concentration) 5% by weight ・ Sodium copper chlorophyllin 0.5% by weight ・ Dipropylene glycol monomethyl ether 5% by weight ・ Diethylene glycol 10% by weight ・ Ion exchanged water 9.5 weight%

Next, an aqueous polymer solution, a solvent and the like were added to the coloring material fine particle dispersion liquid obtained above and the pigment dispersion liquid prepared in Example 15, and each component was added so as to have the following composition,
The ink of Example 17 was prepared by mixing for 2 hours.・ Color material fine particle liquid 40% by weight ・ Pigment dispersion liquid 20% by weight ・ Polymer A (solid content concentration) 5% by weight ・ Copperchlorophyllin sodium 0.5% by weight ・ Diethylene glycol 15% by weight ・ Ion exchange water 19.5% by weight Next, as a comparative example to the above example, Example 16 was repeated except that the thermoreversible thickening polymer and the photosensitizing dye were not used.
And an ink having the same composition as that of Example 17 were prepared and used as the inks of Comparative Example 6 and Example 7. The thermoreversible thickening polymer and the photosensitizing dye were replaced with ion-exchanged water.

[Evaluation] Each of the inks of Examples 1 to 17 and the inks of Comparative Examples 1 to 7 described above was evaluated for ink performance. Performance evaluation items are optical density (OD
Value), feathering, and bleeding. Both evaluations were performed in a constant temperature and constant humidity test room at a temperature of 23 ° C. and a humidity of 60%. Here, each evaluation method will be specifically described. Optical Density (OD Value) A 5 size square 5 mm square solid pattern is printed on an A4 size paper, and the optical density of the print sample after 30 minutes or more is measured. The densities of five solid areas in the printed image were measured with a Macbeth reflection densitometer RD914, and the average value was used as the OD value. The amount of ink applied to the solid portion is 12 nl / mm ²
It is.

Feathering A4 size paper was recorded with dots thinned out every other nozzle of the recording head, and the dots of the print sample after 30 minutes or more were observed with a magnifying glass. The evaluation criteria are the following five levels. 1: Dots without any arc part 2: Dots with bleeding or deformation on 3/4 of the circumference 3: Dots with bleeding or deformation on 1/2 of the circumference 4: Circles Dots with bleeding or deformation on 1/4 of the circumference 5: Round dots

Bleeding An image is formed by using color ink in the A portion (color A) and black ink in the B portion (color B) of the evaluation pattern of FIG. The line position at which the color mixture bleeding occurred was observed and evaluated as the level of bleeding. The evaluation criteria are the following five levels.
In the figure, the A portion is a print pattern of color A, and the B portion is a print pattern of color B, and the boundary between the two colors is indicated by double-headed arrow lines, and 5 lines are recorded at an interval of 1 dot line / 1 dot space. . 1: When bleeding stops within 5 dot lines from the boundary line 2: When bleeding stops within 4 dot lines from the boundary line 3: When bleeding stops within 3 dot lines from the boundary line 4: When bleeding stops within 2 dot lines from the boundary line 5: When bleeding stops within 1 dot line from the boundary line

(Evaluator) As a recording device for the above evaluation,
A bubble jet printer BJC-600J (trade name) manufactured by Canon Inc. shown in FIG. 10 was partially modified and used. The ink was supplied by using the method of filling the ink container 90 for each color with the target ink. The BJC of FIG.
Reference numeral -600J incorporates a mechanism (light source + light transmission unit) for irradiating ink during recording, 100 is a light source (unit array), for example, 12V, 10W halogen lamp, 101 is a light source monitor, 91 Is an ink jet recording head, and 92 is a recording unit in which four 91 recording heads are combined. In the evaluation, the recording head 9
The voltage pulse applied to 1 is applied at a voltage that does not result in ejection, and the ink inside the recording head 91 is kept about 3 ° C. lower than the transition temperature of the thermoreversible thickening polymer used. In this state, a recording pulse was applied to eject ink droplets, and at the same time, the ink adhering to the surface of the paper was irradiated with light from the light source to induce the action of photothermal conversion for recording. Further, the evaluation of the corresponding comparative ink was also performed under the same conditions as those for recording with the ink of the example. For the above evaluation items and evaluation, NP-SK paper for electrophotography (Lot
No. OKK10) was used.

(Evaluation Results) Table 4 shows the evaluation results of the optical density (evaluation item) and feathering (evaluation item) of each ink of Examples and Comparative Examples. Table 5 shows the bleeding (evaluation item) evaluation results when the inks of the examples were combined and printed, and Table 6 shows the bleeding evaluation results when the inks of the comparative example were combined and printed. .

[0088]

[Table 5] Table 4: Optical density and feathering evaluation results (Examples and Comparative Examples)

[0089]

[Table 6] Table 5: Bleeding evaluation results (Examples)

[0090]

[Table 7] Table 6: Bleeding evaluation results (comparative example)

[0091]

From the evaluation results of Table 4, it was found that the ink of the present invention is superior in feathering property to the conventional ink while maintaining a high optical density. Regarding the bleeding, as can be seen from the evaluation results in Tables 5 and 6, when the ink of the present invention is used, the effect of preventing bleeding is large because the effect of preventing color mixing due to rapid thickening on the paper surface is large. Can be said to appear significantly. Especially,
The ink of the present invention has high color development and feathering prevention in color recording on plain office paper such as electrophotographic paper.
It was also found that an excellent effect of preventing bleeding can be obtained. Since the ink of the present invention changes its state only with a change in temperature, the influence of the surface pH and unevenness of the recording material on various recording materials such as transparency film, cloth and metal plate other than plain paper is also affected. It is useful because it is not affected.

As described above, according to the present invention, since the image forming means does not depend only on evaporation and permeation, feathering and bleeding which are essential for high quality recording while obtaining high optical density can be achieved. An ink is provided that solves the problem at the same time. Further, according to the present invention, since the mechanism added for improving the recording property as described above is extremely simple, it is possible to obtain the effect that the power consumption can be suppressed to a low level. Further, the effect of the ink of the present invention is more remarkable when used in combination with an inkjet recording apparatus, and in particular, it was applied to an inkjet recording method that uses thermal energy and a method that uses mechanical energy. In this case, a more remarkable effect appears.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a state change of a thermoreversible thickening polymer-containing ink having a photothermal conversion portion by light irradiation of the present invention.

FIG. 2 is a vertical cross-sectional view of a head portion of an inkjet recording apparatus to which a light irradiation mechanism is added.

3 is a cross-sectional view of a head portion of the inkjet recording apparatus of FIG.

FIG. 4 is an external perspective view of an example of a head having a plurality of nozzles of an inkjet recording device.

FIG. 5 is a perspective view showing an example of an inkjet recording apparatus.

FIG. 6 is a vertical cross-sectional view showing an example of an ink cartridge.

FIG. 7 is a perspective view of a recording unit having a specification in which an inkjet recording head and an ink cartridge are integrated.

FIG. 8 is a vertical cross-sectional view of an inkjet recording head using a piezoelectric element.

FIG. 9 is a bleeding evaluation pattern.

FIG. 10 is a perspective view showing an example of an inkjet recording apparatus provided with a light irradiation mechanism.

[Explanation of symbols]

 1: Head 2: Ink flow path (nozzle) 3: Heating element substrate 4: Protective layer 5: Electrode 6: Heating resistor layer 7: Heat storage layer 8: Substrate 10: Meniscus 11: Ejection orifice 12: Small ink droplet 13 : Recording material 40: Ink storage part (ink bag) 42: Plug 44: Ink absorber 45: Ink cartridge 51: Paper feed part 52: Paper feed roller 53: Paper discharge roller 61: Wiping member (blade) 62: Cap 63: Ink Absorber 64: Ejection Recovery Unit 65: Inkjet Recording Head 66: Carriage 67: Carriage Guide Shaft 68: Carriage Drive Unit (Motor) 69: Drive Belt Unit 70: Recording Unit 71: Head Unit 72: Atmosphere Communication Port 80: Ink flow path (nozzle) 81: Orifice plate 82: Vibration plate 83: Piezoelectric element 84: Base material 90: A Click container 91: inkjet recording head 92: the recording unit 100: light source (unit array) 101: source monitor 102: optical waveguide 103: light irradiation lens

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hiroyuki Maeda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (20)

[Claims] 1. An ink comprising a liquid composition containing a coloring material and a liquid medium, wherein the ink contains a polymer exhibiting thermoreversible viscosity increase and a compound having a photothermal conversion function. Water-based ink for inkjet. 2. An ink comprising a liquid composition containing a coloring material and a liquid medium, wherein the ink contains a polymer exhibiting thermoreversible thickening and having a photothermal conversion part. Water-based ink for use. 3. The water-based inkjet ink according to claim 1, wherein the compound having a photothermal conversion function is a photosensitizing dye. 4. The photothermal conversion part is a photosensitizing dye.
The water-based ink for inkjet as described in. 5. A water-soluble polymer having a cloud point and / or active hydrogen having a nitrogen-containing ring, wherein the polymer having thermoreversible thickening or the polymer having thermoreversible thickening and having a photothermal conversion part A water-soluble vinyl polymer (A) containing 50 wt% or more of a vinyl carboxylic acid ester (a) of an alkylene oxide adduct of a compound as a constituent unit, or a photosensitizing dye bonded to the polymer. The water-based inkjet ink according to claim 1 or 2. 6. A vinyl-based carboxylic acid of an alkylene oxide adduct of an active hydrogen compound having a nitrogen-containing ring, wherein the polymer having thermoreversible thickening or the polymer having thermoreversible thickening and having a photothermal conversion part is A polymer obtained by copolymerizing a monomer composition containing an ester monomer (a) and a monomer represented by the following general formula (I) in a total amount of 50% by weight or more, or The water-based inkjet ink according to claim 1 or 2, wherein a photosensitizing dye is bound to the polymer. Embedded image (However, in the general formula (I), R ₁ is H or C
H ₃ and R ₂ represent H or an alkyl group having 1 to 30 carbon atoms, a (alkyl) phenyl group, or an (alkyl-substituted) aminoalkyl group, n is 2 to 4, m is 2 to 4, and 1 (el) is 2 to 4, x is 2 to 50, y is 0 or 1 to 50, z is an integer of 0 or 1 to 50, and n, m and l are the same number, and n and m or m Except those in which and l are the same number. ) 7. The vinyl carboxylic acid ester (a) according to claim 5 or 6, wherein (substituted) morpholine ethylene oxide and / or propylene oxide 1 to 20.
A water-based inkjet ink that is a (meth) acrylic acid ester of a molar adduct. 8. The ink according to claim 5, wherein a polymer exhibiting thermoreversible thickening or a polymer exhibiting thermoreversible thickening and having a photothermal conversion portion is contained in the ink in an amount of 0.05 to 20 wt%. Item 7. The water-based inkjet ink according to Item 6. 9. The water-based inkjet ink according to claim 1, wherein the coloring material is a dye, and the dye is contained in the ink in an amount of 0.1 to 10 wt%. 10. The water-based inkjet ink according to claim 1, wherein the coloring material is carbon black and / or an organic pigment. 11. The water-based inkjet ink according to claim 1, wherein the coloring material is coloring material particles in which a dye is bonded to the particles to render the dye water-insoluble. 12. The inkjet according to claim 1, wherein the coloring material is a mixture of at least two kinds of coloring materials selected from the coloring materials according to any one of claims 9 to 11. Water-based ink for use. 13. An ink jet recording method, wherein ink droplets containing a recording agent and a liquid medium are ejected from an orifice of a recording head in accordance with a recording signal and adhered to a recording material to perform recording, the ink comprising: Claim 1 or Claim 2
An ink jet recording method, wherein the ink is the ink according to item 1. 14. An ink jet recording method for recording on a recording material by ejecting ink droplets containing a recording agent and a liquid medium from an orifice of a recording head according to a recording signal, wherein the ink is An ink jet recording method, which is the ink according to claim 2, wherein the recording is performed while the temperature of the recording head is kept below the transition temperature of the ink during recording. 15. The recording according to claim 13 or 14, wherein thermal energy is applied to the ink to eject a droplet.
3. The inkjet recording method according to item 1. 16. The ink jet recording method according to claim 13, wherein recording is performed by causing mechanical energy to act on the ink to eject liquid droplets. 17. A recording unit comprising an ink containing portion containing ink and a recording head portion for ejecting the ink as ink droplets, wherein the ink is the ink according to claim 1 or 2. Characteristic recording unit. 18. An ink jet recording apparatus having an ink containing portion containing ink and a recording head portion for ejecting ink as ink droplets, wherein the recording unit is the recording unit according to claim 17. An ink jet recording apparatus characterized by the above. 19. A light irradiation mechanism for irradiating the ink ejected from the recording head with light is further provided.
8. The inkjet recording device according to item 8. 20. The ink jet recording apparatus according to claim 19, wherein the recording unit has a light irradiation mechanism for irradiating the ink with light.