JP3486449B2 - Ink jet recording method and ink jet recording apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink preferably used in an ink jet recording apparatus and an ink jet recording method using the ink, and more specifically, for high quality paper, copy paper, letter paper, thermal transfer paper, wire dot printer paper. The present invention relates to an ink and an inkjet recording method that realizes recording with good fixing property and excellent quality on so-called plain paper such as business form paper.

The invention also relates to a device provided with such an ink.

[0003]

2. Description of the Related Art Conventionally, an aqueous ink in which a water-soluble dye is dissolved in an aqueous medium has been used as an ink jet ink. In these recording liquids, (1) the image having a sufficient density is provided (2) the drying property on the recording material is good, (3) the recorded image has no bleeding, (4) water, alcohol, etc. The recorded image does not flow out even if it comes into contact with it (5) The recorded image has excellent light resistance (6) No jam at the tip of the nozzle occurs (7) When printing continuously or after leaving for a long time It is required that the inconvenience such as blurring of the recorded image does not occur at the start of recording (8), (8) the recording liquid is stable during storage, and (9) there is no problem in user safety. Further, in the ink jet recording system utilizing heat energy, in addition to the above-mentioned requirements, (10) it is necessary that the heat stability is excellent and the heat energy generating element is not adversely affected.

With respect to these required items, in the material composition of the ink jet ink which has been practically used in the past, the above items have a trade-off relationship with each other, and it is difficult to satisfy recent performance requirements.

Most of the conventional inks are composed of a water-soluble dye, water, and a water-soluble organic solvent, and it has been a particularly difficult task to achieve both print quality and fixability. In recent years, a solid jet technology in which solid ink is liquefied and used at the time of ejection has been put into practical use. This is characterized in that the medium material itself has an extremely fast fixing time due to solidification, and therefore the printing quality is high irrespective of the type of paper.
However, solid inks increase printhead temperature by 1
It is necessary to raise the temperature to around 00 ° C., which affects the life of the print head, consumes a large amount of power to maintain the temperature, and has a drawback that the device becomes large. At the same time, the solid ink has a limit even if it is liquefied by increasing the temperature to lower the viscosity, and the frequency response is low, and there is a practical limitation in this respect.

On the other hand, there has been proposed an ink jet ink in which a dye is dissolved or a pigment is dispersed by using a low-viscosity organic solvent as a medium which does not contain water as a main component or does not use water at all. Examples of such solvents include alkyl ethers of ethylene glycols, esters, and pyrrolidones,
Examples include lactones and cyclic carbonates. When these organic solvents are used as the medium, the permeation into the plain paper is quick and a recording liquid having a good fixing property is naturally obtained. Therefore, what must be considered is to maintain the print quality by performing a material treatment to suppress bleeding and strike-through.
The idea is to add a solid substance such as wax or a polymer compound together with the dye component, or to add a binder component together with the pigment dispersion resin.

However, in these methods, when the ink lands on the recording material and the medium components evaporate and permeate to dry, the speed and the viscosity increasing rate of the ink have an appropriate balance. And is considered important in maintaining dignity. However, in many cases, there is a tendency that the fixability is greatly reduced or the quality cannot be maintained.

[0008] Regardless of which side, the method of adding the binder component causes the viscosity of the ink to be high, the response frequency of ejection to be lowered, and the initial responsiveness to be deteriorated due to thickening due to drying at the tip of the nozzle. However, there were some negative effects such as the fact that the practicality was still insufficient.

[0009]

DISCLOSURE OF THE INVENTION The present invention provides an ink jet recording method and apparatus using an ink which satisfies both the fixability and print quality of an aqueous ink and also satisfies the above required performances.
This is a proposal of a new configuration for the storage. It is to solve the above-mentioned drawbacks that cannot be solved by the addition of the existing water-soluble resin of the prior art.

[0010]

The present invention is to achieve the above object . Ie, in some form
The present invention relates to an inkjet recording method. The first form is
Droplets are ejected from the orifice of the recording head according to the recording signal.
Inkjet recording method for recording on recording material
In, as an ink, an ink containing an aqueous liquid medium and the coloring material is dissolved or dispersed this has liquid medium a lower critical solution temperature Tc, phase separation occurs in the range of 40 to 100 ° C. When using ink and recording, the temperature of the recording material
Is kept above the lower critical solution temperature of the liquid medium of the ink
That an ink jet recording method characterized by.

The ink jet recording method of the first embodiment preferably comprises a polymer compound having a lower critical solution temperature in the liquid medium of the ink used, wherein the polymer compound is an N-alkyl substituted acrylic acid. a copolymer comprising an amide
is there. Further, it is preferable that the liquid medium contains a solvent, and the solvent is a compound having a lower critical solution temperature.

Further, the ink jet recording of the first embodiment is
The recording method is preferably performed by the following method. 1) The ink is ejected as droplets by applying thermal energy to the ink. 2) During recording, the temperature of the recording material is kept higher than the lower critical solution temperature of the liquid medium of the ink. 3) During recording, the temperature of the recording head is kept lower than the lower limit critical solution temperature of the liquid medium of the ink, and the temperature of the recording material is kept higher than the lower limit critical solution temperature of the recording medium.

The second mode is to dissolve or disperse the coloring material and the coloring material.
Containing a water-based liquid medium, and the lower critical solution temperature (Tc)
And having a temperature from a temperature lower than the Tc to a temperature lower than the Tc.
Changing the temperature to a higher temperature causes phase separation.
Process of applying ink for inkjet to the recording material as drops
An ink jet recording method comprising:
When the ink drops adhere to the recording material
Ink jet characterized by heating to cause separation
The recording method.

The third mode is to dissolve or disperse the coloring material and the coloring material.
Containing a water-based liquid medium, and the lower critical solution temperature (Tc)
And having a temperature from a temperature lower than the Tc to a temperature lower than the Tc.
Changing the temperature to a higher temperature causes phase separation.
Inkjet recording method using inkjet ink
Inkjet recording ink in a uniform state
A droplet of ink is applied to the recording medium and the
And transferring the ink droplets to the phase-separated state.
Inkjet recording method characterized by including
It

[0015]

The present invention also provides several forms of ink jet.
ET recording device. Of these, the first form
Two forms related to the inkjet recording method
There is a state. A first form is an ink jet recording apparatus including an ink containing portion containing ink and a recording unit having a head for ejecting ink as ink droplets, wherein the ink is a coloring material and an aqueous liquid that dissolves or disperses the coloring material.
An ink containing a medium, wherein the liquid medium has a lower critical solution temperature
Has a temperature Tc and causes phase separation in the range of 40 to 100 ° C.
The present invention relates to an ink jet recording apparatus, which is an ink and has means for heating a recording material .

The second embodiment comprises a recording head for ejecting ink droplets, an ink cartridge having an ink accommodating portion for accommodating ink, and an ink supply portion for supplying ink from the ink cartridge to the recording unit. and an ink jet recording apparatus, ink, color
Ink containing a material and an aqueous liquid medium that dissolves or disperses it
And the liquid medium has a lower critical solution temperature Tc,
It is an ink that causes phase separation in the range of ~ 100 ° C.
The present invention relates to an ink jet recording apparatus including a means for heating a recording material .

Here, in the ink jet recording apparatus of the first and second embodiments, preferably, the liquid medium of the ink to be used contains a polymer compound having a lower critical solution temperature, and the polymer compound Is a copolymer containing N-alkyl substituted acrylic acid amide . Further, the liquid medium contains a solvent, and the solvent is a compound having a lower critical solution temperature .

On the other hand, the inkjet recording apparatus of the third mode is related to the inkjet recording methods of the second and third modes. That is, in an ink jet recording apparatus including an ink containing portion containing ink and a recording unit having a head portion for ejecting ink as ink droplets, the ink contains a coloring material and an aqueous liquid medium that dissolves or disperses the coloring material. , And the lower critical solution temperature (T
The ink having c), which causes phase separation by changing the temperature from a temperature lower than the Tc to a temperature higher than the Tc, and is provided with a means for heating the recording material. The present invention relates to an inkjet recording device. Here, the ink used in the inkjet recording apparatus of the third embodiment is spinodal decomposed . Further, the ink suitable for such an embodiment contains a polymer compound that causes phase separation in the ink, and the polymer compound is dissolved in the ink when the temperature of the ink is lower than Tc. , and the such a polymer compound, are those polymers having a N-alkyl substituted acrylamide as a monomer unit.

Further, in any of the ink jet recording apparatuses according to the first to third embodiments, the head portion has a head for ejecting the ink as droplets by applying thermal energy to the ink .

In the present invention, when the high molecular compound having the lower critical solution temperature is contained in the ink, the shape of the single dot itself does not collapse due to the phase separation due to the temperature rise, and a printed material with a sharp edge is obtained. To be The phase separation caused by the lower critical eutectic temperature, which can be said to be the principle of the present invention, means that a high-viscosity droplet containing a large amount of a polymer and a coloring material is contained in a medium that does not contain a high-viscosity polymer or coloring material. , Which means that a large number will be dispersed. Since the thick droplets generated in the system do not easily flow, they tend to stay on the surface of the paper and are less likely to be mixed with each other due to mutual diffusion. Therefore, it is considered that the deterioration of the quality due to the excessive permeation of the coloring material is suppressed even if the medium itself contains the permeable material. Since this phenomenon occurs due to the action of heat, in the case of an ink jet recording apparatus based on the principle that the action of heat causes the ink itself to foam to produce ejection energy, the heat of foaming causes phase separation to proceed, It is possible that microscopic droplets are in a dispersed state at the time of landing on. In this case, the recording paper may be heated to the minimum limit, and in some cases, the same effect can be obtained without heating at all.

The principle of the present invention will now be described using spinodal wires. Regarding spinodal wire, for example, "Chemical Thermodynamics" by Prigogine / Defay (Misuzu Shobo,
Japan), P. Glansdorff / I. Prigog
ine Structure. stability.
and fluctuations (Wiley-In
It is described in detail in books such as terence London). The spinodal line represents a boundary line that separates the metastable region and the unstable region in the phase equilibrium diagram regarding the composition and the temperature when the binary system of A and B is taken as an example (FIG. 1). It is known that the speed of the phase separation phenomenon in the metastable region and the unstable region greatly differs at the boundary of this line. Now, assume that the temperature is jumped from T1 to T2. Compositions 1 and 3 will jump to the metastable region, and composition 2 will jump to the unstable region. Starting from any of Compositions 1 to 3, two equilibrium compositions are reached after a sufficient time has elapsed.

However, in the process, the characteristic of the metastable region: the formation of a new phase that is easily overcooled is the mechanism of nucleation and growth. The formation of the phase is slow. The characteristic of the unstable region: the formation of a new phase that is difficult to supercool. Starts at a dash from the state where the whole system called spinodal decomposition becomes unstable at the same time.

Incomplete phase formation is fast It is known to have the difference.

What is noted here is the fact that the phase separation from the inside of the spinodal line, that is, the unstable region, is 1000 times faster than the speed from the metastable region.

The present invention is characterized in that this phenomenon is applied to a specific ink system.

By the rapid phase separation of spinodal decomposition, 1. Causes the separation of liquid and solid components, 2. Accelerate pervaporation of media components from the dilute phase 3. Accelerates fixation of colorant components in the rich phase Of.

For the reason why the phases are formed faster in the spinodal decomposition, see J. W. Cahn, The Jou
rnal of Chemical Physics;
42 , (1) 93 (1965) and other papers give detailed theoretical explanations. For the polymer solution system,
J. J. Van. Aartsen, EuropeanP
polymer Journal; 6 , 919 (197)
0) etc. have reported the measurement results.

Based on the above principle, a specific ink composition of the present invention will be described.

The ink of the present invention comprises a polymer compound, a solvent and a coloring material. The factors that characterize the inks of the present invention are polymer / solvent systems and their composition, and T1, Tc, T
It is 2.

A particularly preferred polymer compound used in the ink of the present invention is a water-soluble polymer compound having a large number of hydrogen bonding groups, which is a compound which causes sharp phase separation. They are, for example, Research Report No. 144 (1984), a research report by Shoji Ito et al. Discloses N-alkyl-substituted acrylic acid amides disclosed as polymer compounds having thermoreversible properties. Examples of these include poly (N-ethylacrylamide), poly (Nn-propylacrylamide), poly (Nn-propylmethacrylamide),
Poly (N-n-isopropylacrylamide), poly (N-n-isopropylmethacrylamide), poly (N-cyclopropylacrylamide), poly (N-cyclopropylmethacrylamide), poly (N, N-diethylacrylamide), Examples include poly (N, N-diethylmethacrylamide). Other examples include poly (N, N-acrylpyrrolidone), poly (N-acrylpiperidine), and copolymers thereof, alternating copolymers of polyisobutyl vinyl ether and maleic anhydride, poly (2-methyl-5--5). Vinyl pyridine), poly (vinyl alcohol), poly (N-vinyl pyrrolidone), poly (N
-Vinyl succinic acid), poly (vinyl sulfonic acid); poly (n-butyl methacrylate), poly (dodecyl methacrylate), poly (n-hexyl methacrylate), poly (methyl methacrylate), poly (n-octyl methacrylate), etc. (Meth) acrylic acid alkyl ester; poly (oxyethylene), poly (tetrahydrofuran), amylopectin, amylose, poly (vinyl acetate), poly (propylene glycol), and the like. Among these polymer compounds, N-alkyl-substituted acrylamide polymers are particularly preferable because they show a sharp phase transition.

The following solid compounds having a relatively low molecular weight can also be used in the ink of the present invention. They are fatty acids such as lauric acid and stearic acid, higher alcohols such as cetyl alcohol and stearyl alcohol,
1,6-hexanediol, 1,10-decanediol, 1,12-dodecanediol, 2,2-dimethylolpentane, and other diols, ethylene carbonate, 12-hydroxystearic acid monoglyceride,
Esters such as glycerin monostearate, and natural waxes such as paraffin wax and candelilla wax.

Next, as the solvent to be used, a solvent having low volatility, low viscosity and excellent stability and having a lower critical solution temperature with the above-mentioned polymer compound or solid compound is selected. They are water, ethyl carbitol,
Methyl cellosolve, tetrahydronaphthalene, t-butanol, ethanol, isopropyl alcohol, methanol, n-propanol, n-amyl alcohol, urea, dioxane, diethylene glycol diethyl ether, butanone, acetic acid buffer, NaCl / water, KBr.
/ Water, KCl / water, NaBr / water, KNO ₃ / water, K ₂
SO ₄ / water, MgSO ₄ / water, ethylene carbonate,
Propylene carbonate, higher fatty acid, fatty acid amide,
Dimethylolpropionic acid, hydrocarbon wax, and the like.

In the present invention, preferable combinations of polymer / solvent system are as follows.

N-ethylacrylamide, Nn-pro
Pyracrylamide, N-n-propylmethacrylic acid
Mido, N-n-isopropylacrylamide, N-n-
Isopropyl methacrylamide, N-cyclopropyl
Acrylamide, N-cyclopropyl methacrylate
N, N-diethyl acrylamide, N, N-diethyl
Lumethacrylamide, N, N-acrylpyrrolidone,
N-acrylic piperidine, and copolymers thereof with water
Mixed system of polyisobutyl vinyl ether and anhydrous male
Mixed system of alternating copolymer of acid and NaCl and water
Nyl alcohol / t-butanol / water mixture
Nyl alcohol, ethanol and water mixture, polyvinyl
Mixed system of alcohol, methanol and water, polyvinyl alcohol
Coal, isopropanol and water mixture, polyvinyl alcohol
Rucol, n-propanol and water mixture, polyvinyl
Mixed system of alcohol, NaCl and water, poly-N-vinyl
Pyrrolidone / NaCl / water mixture, poly-N-vinyl
Succinamide / NaCl / water mixture, polyvinyls
Rufonic acid and KBr or KCl or NaBr
Or a mixed system of NaCl and water, poly-n-butyl methacrylate
Of polydodecyl meta, a mixed system of sodium acetate and methyl cellosolve
Mixed system of acrylate and n-amyl alcohol, poly-n
-Hexyl methacrylate, urea and water mixture, polymer
Mixed system of chill methacrylate, dioxane and water, polio
Xyethylene and diethylene glycol diethyl ether
Mixed system with polyoxyethylene, KCl, NaCl,
KNO ₃, MgSO_Four, K₂SO_FourAnd the like mixed with water
System, mixed system of polytetrafuran and butanone, amylope
Of cutin and water, amylose and KCl and water
It is a mixed system.

As the coloring material used in the present invention, a water-soluble dye such as a direct dye, an acid dye, a food dye, a basic dye, a reactive dye, a vat dye or a pigment dispersion is used.
Examples of the pigment include azo type, phthalocyanine type, quinacridone type, anthraquinone type, dioxazine type, indigo, thioindigo type, perinone type, isoindolinone type, azomethine azo type and carbon black. When a pigment is used as a coloring material, it needs to be treated as a dispersion with a dispersant in advance. A suitable dispersant for obtaining a dispersion using water is JP-A-56-147863.
Using an addition polymerization type polymer dispersant as disclosed in
The production is preferably in accordance with the dispersion method disclosed in JP-A-2-255875. The coloring agent used in the present invention may be used in any concentration as long as it gives a sufficient coloring density to the recording material, but generally, the proportion of 2 to 10% by weight in the ink is preferable. .

The points to be noted in selecting materials among the materials listed above are as follows: Dispersant The solvent that constitutes the spinodal decomposition system of the polymer must have uniform solubility. 2. The dispersant polymer and the polymer that constitutes the spinodal decomposition system do not have to have compatibility with each other, but must not separate into two phases in the solvent system. is necessary.

Solvents that can be additionally used in the present invention include ethylene glycol, diethylene glycol, triethylene glycol, tripropylene glycol, glycerin, 1,2,4-butanetriol, 1,2,2, which have excellent moisturizing properties. 6-hexanetriol, 1,2,5-
Pentanetriol, 1,2-butanediol, 1,3
-Butanediol, 1,4-butanediol, dimethyl sulfoxide, diacetone alcohol, glycerin monoallyl ether, propylene glycol, butylene glycol, polyethylene glycol 300, thiodiglycol, N-methyl 2-pyrrolidone, 2-pyrrolidone,
γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, sulfolane, trimethylolpropane, trimethylolethane, neopentyl glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol mono Allyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether,
β-dihydroxyethylurea, urea, acetonylacetone, pentaerythritol, 1,4-cyclohexanediol and the like can be used. As a solvent with excellent permeability, hexylene glycol, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, ethylene glycol monophenyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, triethylene. Glycol monobutyl ether,
Triethylene glycol dimethyl ether, triethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether Ether, glycerin monoacetate, glycerin diacetate, glycerin triacetate, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, cyclohexanol, 1,2-cyclohexanediol, 1-butanol, 3-methyl-1,5-pentanediol, 3 -Hexe 2,5-diol, 2,3
Butanediol, 1,5-pentanediol, 2,4-
Pentanediol and 2,5-hexanediol can be used. Evaporative substances include ethanol and n
-Propanol, 2-propanol, 1-methoxy-2
-Propanol, furfuryl alcohol, tetrahydrofurfuryl alcohol, etc. can be used. With respect to the compounding ratio of each material in the ink, the polymer compound exhibiting the lower limit critical solution temperature is suitably in the range of 0.5 to 5% by weight and effective. If it is less than this range, the effect of phase separation does not appear clearly, and if it is too large, the viscosity of the ink increases, and a clear adverse effect appears on droplet formation and ejection.

The colorant concentration is 0.5 to 5 depending on the coloring power.
A weight% range is preferred.

As the medium material, the medium constituting the phase separation system of the polymer is mainly used, and the amount of them is 50% to 80% of the whole medium. The balance is the solvent necessary to improve the moisturizing property.

The main components constituting the ink of the present invention are as described above, but other various dispersants, surfactants, viscosity modifiers, surface tension modifiers, optical brighteners, antioxidants,
An antifungal agent, a pH adjusting agent and the like can be added, if necessary, within a range not hindering the achievement of the object of the present invention.

The ink of the present invention is manufactured as follows when a pigment is used as a coloring material. 1. Dispersing a given pigment with a suitable dispersant polymer.

As the dispersion medium, a solvent used in ink or a solvent system is used. However, it is also possible to supplementarily use a different solvent in the dispersion operation. 2. A polymer compound solution forming a spinodal decomposition system is added to the dispersion. 3. A final composition is obtained by adding a solvent for composition adjustment, an additive for imparting ink characteristics, and the like.

In the ink using the spinodal decomposition system of the present invention, when the ink droplets ejected from the recording head at the temperature T1 (<critical temperature Tc) land on the recording paper, the droplet temperature becomes T2 (T2 is It is usually higher than room temperature and rises to T2> Tc). Due to this temperature rise, the system enters the unstable region in the phase equilibrium diagram, and the system (liquid film consisting of landed droplets)
The formation of a new phase occurs throughout the. The new phase generated here is usually divided into a rich phase and a dilute phase. Since the dilute phase is mainly composed of a solvent, evaporation is promoted and at the same time, the dilute phase quickly penetrates into the recording paper. On the other hand, the thick phase is apt to be anchored on the surface of the recording paper, which is advantageous for fixing the colorant on the surface without permeating.

In this way, the ink of the present invention promptly becomes unstable in the system due to the rise in temperature, and since it is the formation of two phases having different concentrations, it is initially in the state of a low-viscosity solution. It can be seen that the inkjet system using ink uses a suitable principle.

The ink of the present invention can be suitably applied to general ink jet recording systems in general, but is particularly preferable when it is applied to an ink jet recording method of a type in which ink is ejected due to the bubbling phenomenon of ink due to thermal energy. .

The lower limit critical solution temperature of the polymer compound can be adjusted by the kind, molecular weight and addition amount of the polymer compound having the lower critical solution temperature used. It can also be adjusted by the solvent used and the amount of the solvent, or addition of an appropriate inorganic salt.

Next, an example of an ink jet recording apparatus suitable for recording with the ink of the present invention will be described below. An example of the head configuration, which is the main part of the apparatus, is shown in FIGS.

The head 13 is obtained by adhering a glass, ceramic or plastic plate or the like having a groove 24 for letting ink pass through and a heating head 15 used for thermal recording.
The heating head 15 has a protective film 1 formed of silicon oxide or the like.
6, aluminum electrodes 17-1 and 17-2, a heating resistor layer 18 formed of nichrome, a heat storage layer 19, and a substrate 20 having a good heat dissipation property such as alumina.

The ink 21 has a discharge orifice (fine hole) 2
2, the meniscus 23 is formed by the pressure P.

Now, when electric signal information is applied to the electrodes 17-1 and 17-2, the area indicated by n of the heating head 15 rapidly generates heat, and bubbles are generated in the ink 21 in contact therewith, The pressure causes the meniscus 23 to project, the ink 21 to be ejected, and the recording droplets 24 are formed from the orifice 22 and fly toward the recording material 25. FIG. 4 shows an external view of a multi-head in which many heads shown in FIG. 2 are arranged. The multi-head is manufactured by closely adhering a glass plate 27 having a multi-groove 26 and a heating head 28 similar to that described in FIG. 2 is a cross-sectional view of the head 13 along the ink flow path, and FIG. 3 is a cross-sectional view taken along the line AA of FIG.

To raise the temperature of the ink of the present invention and hold it in the recording head, the substrate 20 may be heated to adjust the temperature of the entire head to a constant temperature. Figure 5
An example of an ink jet recording apparatus incorporating the above head is shown in FIG.

In FIG. 5, reference numeral 61 denotes a blade as a wiping member, one end of which is held by a blade holding member to become a fixed end, which is in the form of a cantilever. The blade 61 is arranged at a position adjacent to the recording area of the recording head, and in the case of this example, is held in a protruding form in the movement path of the recording head. Reference numeral 62 denotes a cap, which is disposed at a home position adjacent to the blade 61, and has a configuration in which it moves in a direction perpendicular to the moving direction of the recording head and contacts the ejection port surface to perform capping. Further, 63 is an ink absorber provided adjacent to the blade 61, and like the blade 61, is held in a form protruding in the moving path of the recording head. The blade 61, the cap 62, and the absorber 63 form an ejection recovery unit 64, and the blade 61 and the absorber 63 remove water, dust, and the like from the ink ejection port surface. Reference numeral 65 denotes a recording head which has an ejection energy generating means and ejects ink to a recording material facing the ejection port surface where the ejection ports are arranged for recording, and 66 denotes a recording head 65 mounted to move the recording head 65. It is a carriage for performing. The carriage 66 slidably engages with the guide shaft 67, and 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 be moved.
It is possible to move the recording area and its adjacent area.

Reference numeral 51 denotes a paper feed section for inserting a recording material,
A paper feed roller 52 is driven by a motor (not shown). With these configurations, the recording material is fed to a position facing the ejection port surface of the recording head, and is ejected to a paper ejection unit provided with a paper ejection roller 53 as the recording progresses.

In order to keep the recording paper at a temperature higher than room temperature, (1) as shown in FIG. 8 (A), the infrared heater 10 and the blower fan 11 are arranged on the upper surface or the lower surface of the recording paper conveyance path. And heat with radiant heat, (2) Figure-8
As shown in (B), the sheet heating element 12 is placed in the transport path and heated directly. (3) As shown in FIG. 8C, a heater is built in the paper feed roller (3a or 3).
b) It is preferable to take a method such as heating from below the paper by heat conduction.

In the above structure, when the recording head 65 returns to the home position after recording is completed, the cap 62 of the head recovery section 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 surface 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.

When the recording head 65 moves 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 during wiping. As a result, the ejection opening surface of the recording head 65 is wiped even during this movement. The above-mentioned movement of the recording head to the home position is performed not only at the end of recording and at the time of ejection recovery, but also at a predetermined interval while the recording head moves in the recording area to the home position adjacent to the recording area. However, the wiping is performed along with this movement.

FIG. 6 is a diagram showing an example of an ink cartridge 45 in which ink is supplied to the head through an ink supply member, for example, a tube. Where 4
Reference numeral 0 is an ink containing portion containing the supply ink, for example, an ink bag, and a rubber stopper 42 is provided at the tip thereof. By inserting a needle (not shown) into this stopper 42, the ink in the ink bag 40 can be supplied to the head. Reference numeral 44 is an absorber that receives waste ink. As the ink containing portion, the liquid contact surface with the ink is polyolefin,
Those formed of polyethylene are particularly preferable for the present invention. The ink jet recording apparatus used in the present invention is not limited to the above-described head and ink cartridge which are separate bodies, but is preferably used as an integrated one as shown in FIG.

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 plurality of orifices. Head portion 71
It is configured to be ejected as an ink droplet from. It is preferable for the present invention to use polyurethane, cellulose or polyvinyl acetal as the material of the ink absorber. Reference numeral 72 is an atmosphere communication port for communicating the inside of the recording unit with the atmosphere. This recording unit 70 is
It is used in place of the recording head shown in FIG. 5, and is detachable from the carriage 66.

[0060]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. Examples 1 to 3, Reference Examples 1 to 2 and Comparative Examples 1 to 4 The water-soluble polymers shown in Table 1 were prepared as compounds having a lower critical solution temperature in water. In the same table, the molecular weight of these compounds and the lower limit critical solution temperature are described.

Next, the above compounds were used and the respective components shown in Tables 2 to 5 were mixed to prepare an ink of the present invention. The procedure for making the ink is to first prepare an aqueous solution with a selected concentration in the range of 1 to 5%. Next, to this aqueous solution, water, an organic solvent, a dye, and a surfactant were added in a predetermined amount in this order to prepare a high polymer concentration, and after stirring for 5 hours, a membrane filter with a pore size of 0.22 μm ( Product name:
It was filtered with a Fluoropore filter, manufactured by Sumitomo Electric Co., Ltd.) to obtain four color inks of black, yellow, magenta and cyan for each example of the present invention.

The compositions of the four color inks are shown in Tables 2 to 5, and the numbers in each table represent the parts by weight of each component.

Further, as comparative examples, inks having the same compositions as in Examples 1 to 3 and Reference Example 1 except that the water-soluble polymer was not used were prepared as the inks of Comparative Examples 1 to 4. However, the water-soluble polymer was replaced with water.

Table 6 shows the ink viscosities η (cps) at 25 ° C., the operating temperature Th, and the paper temperature Tp of the inks of Examples , Reference Examples and Comparative Examples.

Next, an ink jet printing apparatus was prepared in which four bubble jet recording heads having 256 nozzles at 400 dpi were arranged in a line in the main scanning direction of the head. Examples 1 to 3, Reference Examples 1 and 2 and Comparative Examples 1 and 2 prepared as described above through the ink supply system tubes to each recording head.
4 inks were filled and a printing test was conducted.

The recording head is controlled to the operating temperature Th corresponding to the ink of each embodiment, and the recording paper is provided with a heater in the platen roll so that the surface temperature of the paper becomes Tp during recording. Was set and recorded. The ink amount in the full-solid printing portion of each color is 10 nl / mm ² . With respect to the obtained printed matter, the properties of color developability, fixability, and ink bleeding were measured by the following methods. Tables 7 and 8 show the results of the evaluation of these three items. (1) Fixability evaluation Blue solid printing (cyan ink and magenta ink 100% duty overlap printing) on commercially available electrophotographic papers, and after 10 seconds and 30 seconds, the printing portion is strained (product name No. 5C). Rubbed by Toyo Sougami Co., Ltd. and evaluated according to the following criteria.

⊚: No stain in 10 seconds.

◯: There was slight blurring in 10 seconds and no blurring in 20 seconds.

Δ: Slight blurring in 20 seconds, no blurring in 30 seconds.

X: Blurred after 30 seconds. (2) Color development evaluation The reflection density of the 100% solid print part of each color is Macbeth RD-
It was measured using a 918 reflection densitometer and evaluated as the color developability. (3) Printing Bleeding Character printing was performed with black ink, and then yellow ink 100% duty solid printing was performed to evaluate the printing quality of the character and ranked as follows.

⊚: No bleeding at all.

◯: There is no bleeding, but some feathering occurs in the characters.

Δ: Blurring occurs and the outline of the character is slightly broken.

X: A level at which bleeding is severe and characters cannot be read at all.

(A level of ◯ or more indicates a level that causes no problem in actual use.) As is clear from Examples 1 to 3, Reference Examples 1 and 2 , and Comparative Examples 1 to 4, the ink and the ink jet recording method of the present invention are used. For example, a recorded image with good printability on plain paper can be obtained, but none of the comparative examples satisfied all of the color developability, print bleeding, and fixability.

In the ink using the polymer compound having the lower critical eutectic temperature of the present invention, the liquid medium of the ink is a uniform solution system at room temperature, and in the temperature range of 40 ° C. to 100 ° C. Separation, that is, a high molecular compound having an aqueous lower critical co-solubilization temperature is deposited in a recording liquid to form a dispersed state, whereby a recorded image with good printability on plain paper can be obtained. As a result, even in color recording using plain paper, a recorded matter having excellent fixing properties and good image quality is formed.

[0077]

[Table 1]

[0078]

[Table 2]

[0079]

[Table 3]

[0080]

[Table 4]

[0081]

[Table 5]

[0082]

[Table 6]

[0083]

[Table 7]

[0084]

[Table 8] Example 4 (Preparation of pigment dispersion liquid) Styrene / acrylic acid / butyl acrylate copolymer 2 parts (glass transition temperature 74 ° C., acid value 230, molecular weight 6700) Monoethanolamine 0.5 part Ion-exchanged water 80 parts The above components , And heat to 50 ℃ in a water bath,
Completely dissolve the resin component. Carbon black (MA-100, manufactured by Mitsubishi Kasei) 15 newly made in this solution
Parts were added, and after premixing for 30 minutes, dispersion treatment was performed under the following conditions.

Disperser Sand grinder Grinding media Glass beads (1 mm diameter) Filling ratio of grinding media 50% (volume) Dispersion time 3 hours Further centrifugal separation treatment (12000 rpm, 20 minutes)
Coarse particles were removed to obtain a dispersion liquid. (Preparation of ink) Dispersion (solid content: about 15%) 30 parts Polyvinyl alcohol (saponification degree 85%, number average molecular weight 70,000) 6.0 parts t-butanol 32 parts Ion-exchanged water 42.5 parts Thus, an ink containing 4.5 parts of the pigment dispersion in a medium system of polyvinyl alcohol: t-butanol: water = 6.0: 32.0: 42.5 (weight ratio) was prepared. The dispersion treatment step was performed at room temperature, and after the final formulation was prepared, the ink temperature was maintained at 20 ° C. and used in the following printing test. The Tc of this ink is about 25 ° C. Example 5 (Preparation of Pigment Dispersion) Styrene / acrylic acid / ethyl acrylate copolymer 2.5 parts (glass transition temperature 87 ° C., acid value 1750, molecular weight 11000) aminomethyl propanol 0.5 parts ion-exchanged water 79. 0 part To this resin solution, 13 parts of carbon black (MCF88, manufactured by Mitsubishi Kasei) was added, and a dispersion was prepared in the same manner as in Example 4 . The solid content of this dispersion was 16% by weight. (Preparation of ink) 30 parts of the above dispersion liquid Alternating copolymer of polyisobutyl vinyl ether and maleic anhydride (number average molecular weight of 15,000) (solid content) 3.0 parts Sodium chloride 5.85 parts Ion-exchanged water 74.8 After blending parts, the temperature was maintained at 20 ° C. and used in the following tests.
The Tc of this ink is about 25 ° C. Example 6 (Preparation of pigment dispersion) Methyl methacrylate / acrylic acid / hydroxyethyl methacrylate copolymer (glass transition temperature 86 ° C., acid value 145, molecular weight 7500) 1.5 parts monoethanolamine 0.5 parts diethylene glycol diethyl ether 47.5 parts Water 30 parts Mixing the above components and using carbon black (S170, made by Degussa) 15 parts, solid content 1 in the same manner as in Example 4.
A 5% dispersion was obtained. (Preparation of Ink) Dispersion 30 parts Polyoxyethylene (molecular weight 2000) 10 parts Diethylene glycol diethyl ether 60 parts The ink thus prepared was maintained at 25 ° C. and used for the following evaluations. The Tc of this ink is
It is about 50 ° C. Comparative Examples 5 to 7 Comparative inks of Comparative Examples 5 and 6 were prepared by adding inks containing diethylene glycol to the inks of Examples 4 to 6 without adding the resin added at the time of ink preparation. , 7.

The inks of Examples 4 to 6 and Comparative Examples 5 to 7 were provided with band-shaped heating elements, and the temperature of the recording paper was 70 ° C.
Adjusted printer Inkjet recording head (24 nozzles, 180 with a print head of the bubble jet system having a d pi)] mounted and performance evaluation of the following three items was performed. 1) Print density 2) Bleeding occurrence rate 3) Drying time evaluation method: [Print density] Electrophotographic copy paper (NP dry, plain paper for Canon copiers) was driven simultaneously with all nozzles, and 1.3 cm x 2 ．
A solid printing batch of 0 cm was prepared, dried for 24 hours, and then the optical density of the batch was measured. [Bleed occurrence rate] Ten lines of 12-point alphanumeric characters were printed on plain paper, and the sharpness of the print was evaluated.

⊚: The printing is clear with almost no bleeding. Δ: Some bleeding is felt. X: The bleeding is severe and unclear. [Drying time] 1 alphanumeric character on a commercially available electrophotographic copy paper.
After printing the page, the printed portion was rubbed with a cleaning paper after 3, 5, 10 and 15 seconds, and the number of seconds until the printed portion was not stained was measured.

The results of these evaluations are summarized in Table 9. As can be seen from Table 9, the ink of the present invention based on the principle of phase separation of the spinodal decomposition type has excellent print density, print quality and dryness.

[0089]

[Table 9] Examples 7 to 9 Using the methacrylic acid alkyl ester type polymers shown in Table 10, black inks having the compositions shown in Table 11 were prepared in the same manner as in Examples 1 to 3, and the print density, the fixability, and the
The print bleeding was evaluated. The results are shown in Table 12.

It can be seen that good results are obtained also in the case of these phase change polymers.

[0091]

[Table 10]

[0092]

[Table 11]

[0093]

[Table 12]

[0094]

EFFECTS OF THE INVENTION By using the spinodal decomposition type phase separation ink of the present invention, quick phase separation due to temperature rise suppresses permeation of thick phase having high coloring material concentration into paper. The print density. In addition, since penetration into small voids is suppressed, bleeding can be reduced at the same time. Further, the dilute phase having a low colorant concentration quickly permeates or evaporates, so that apparent drying is stopped and the fixing property can be improved.

[Brief description of drawings]

FIG. 1 is a phase equilibrium diagram for explaining the principle of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration example of a head of the present invention.

3 is a sectional view taken along line AA of FIG.

FIG. 4 is an external view illustrating a multi-head in which a large number of heads shown in FIG. 2 are arranged.

FIG. 5 is a perspective view illustrating an inkjet recording apparatus incorporating the head of the present invention.

FIG. 6 is a cross-sectional view illustrating an example of an ink cartridge that stores ink to be supplied to the head via an ink supply tube.

FIG. 7 is a perspective view illustrating an example of an inkjet recording device in which a head and an ink cartridge are integrated.

FIG. 8 is a schematic diagram illustrating a structure of a printer including a heating unit. (A) The heating means is an infrared heater (B) The heating means is a planar heating element (C) The heating means is a heating roller

[Explanation of symbols]

1 print head 2 sheets 3a, 3b heating roller 4a, 4b transport rollers 4c, 4d discharge roller 5 Platen 6 carriage 7 Pressing part 8 main scanning rails 9 pressure roller 10 heater 11 fans 12 Sheet heating element 13 heads 14 groove 15 heating head 16 Protective film 17-1, 17-2 Aluminum electrode 18 Heating resistor layer 19 Heat storage layer 20 substrates 21 ink 22 Discharge orifice 23 Meniscus 24 recording droplets 25 Recorded material 26 multi groove 27 glass plate 28 heating head 40 ink bags 42 Stopper 44 ink absorber 45 ink cartridge 51 paper feeder 52 Paper feed roller 53 Paper ejection roller 61 blade 62 cap 63 ink absorber 64 Discharge recovery unit 65 recording head 66 carriage 67 Guide shaft 68 motor 69 belt 70 recording unit 71 Head 72 Air communication port

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI B41J 3/04 102Z (72) Inventor Akio Kashiwazaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Invention Takafumi Takaide 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-4-39365 (JP, A) JP-A-4-356570 (JP, A) JP-A 4-180973 (JP, A) JP 63-237984 (JP, A) JP 3-190740 (JP, A) JP 1-272673 (JP, A) JP 6-100807 (JP, A) JP-A-5-117561 (JP, A) JP-A-5-263029 (JP, A) JP-A-6-192605 (JP, A) International publication 92/020749 (WO, A1) (58) Field (Int.Cl. ⁷ , DB name) C09D 11/00 B41J 2/01 B41J 2/175 B41M 5/00 C0 9D 11/02

Claims (24)

(57) [Claims] 1. A recording head for recording ink droplets according to a recording signal.
Ink for recording on the recording material by discharging from the orifice
In Kujetto recording method, the ink, encounters the ink containing coloring material and an aqueous liquid medium for dissolving or dispersing this
And the liquid medium has a lower critical solution temperature Tc of 40 to 1
Use an ink that causes phase separation within the range of 00 ° C and record
Occasionally, the temperature of the recording material will change to the lower critical solubility of the liquid medium of the ink.
Ink jets characterized by holding above the temperature
Recording method . 2. The ink jet recording apparatus according to claim 1, wherein the liquid medium contains a polymer compound having a lower critical solution temperature.
Recording method . 3. A polymer compound, b according to claim 2 is a copolymer comprising a N-alkyl-substituted acrylic acid amide
Recording method . 4. The method according to claim 1, wherein the liquid medium contains a solvent, and the solvent is a compound having a lower critical solution temperature.
Inkjet recording method . 5. The ink according to claim 1, wherein the ink is ejected as droplets by applying thermal energy to the ink .
The ink jet recording method according to any one of claims. 6. A kept below the lower critical solution temperature of the ink in the liquid medium the temperature of the recording head during recording, hold higher than the lower limit critical solution temperature the temperature of the recording material according to claim 1
7. The inkjet recording method according to any one of 5 to 10. 7. An ink jet recording apparatus comprising a recording unit having an ink containing portion containing ink and a head portion for ejecting ink as ink droplets, wherein the ink is a coloring material and an aqueous liquid for dissolving or dispersing the coloring material. Including medium
The liquid medium has a lower critical solution temperature Tc.
Ink that has and causes phase separation within the range of 40 to 100 ° C
And an inkjet recording apparatus comprising means for heating a recording material . 8. A lower critical solution temperature in the liquid medium
The inkjet recording according to claim 7, which comprises a polymer compound.
Recording device . 9. The polymer compound is an N-alkyl-substituted acetic acid.
9. The copolymer according to claim 8, which is a copolymer containing a phosphoric acid amide.
Recording device . 10. A liquid medium containing a solvent, the solvent comprising:
The compound according to claim 7, which is a compound having a lower critical solution temperature.
Inkjet recording device . 11. The ink jet recording apparatus according to claim 7, wherein the head portion has a head for ejecting the ink as droplets by applying thermal energy to the ink. 12. An inkjet recording apparatus comprising a recording head for ejecting ink droplets, an ink cartridge having an ink accommodating portion for accommodating ink, and an ink supply portion for supplying ink from the ink cartridge to the recording head, The ink dissolves the coloring material and
An ink containing an aqueous liquid medium to be dispersed, wherein the liquid medium is
It has a lower critical solution temperature Tc and is in the range of 40 to 100 ° C.
The ink that causes phase separation in the
An ink jet recording apparatus characterized by comprising a stage. 13. The liquid medium has a lower critical solution temperature.
The ink jet ink according to claim 12, further comprising a polymer compound.
Recording device . 14. The polymer compound is an N-alkyl substituted alkyl group.
The copolymer according to claim 13, which is a copolymer containing acrylic acid amide.
Inkjet recording device . 15. A solvent is contained in the liquid medium, and the solvent is
The compound according to claim 12, which is a compound having a lower critical solution temperature.
Inkjet recording device . 16. A recording head ejects ink as droplets by applying thermal energy to the ink.
The ink-jet recording apparatus according to any one of that請 Motomeko 12-15. 17. An ink jet recording apparatus comprising an ink containing portion containing ink and a recording unit having a head portion for ejecting ink as ink droplets,
The ink contains a coloring material and an aqueous liquid medium that dissolves or disperses the coloring material.
An ink that contains and has a lower critical solution temperature (Tc)
Then, the temperature is changed from a temperature lower than the Tc to the Tc.
Change to a higher temperature to produce phase separation.
An ink jet recording apparatus, comprising: means for heating a recording material . 18. The ink jet recording apparatus according to claim 17 , wherein the ink decomposes by spinodal. 19. The ink contains a polymer compound that causes phase separation in the ink, and the polymer compound is dissolved in the ink when the temperature of the ink is lower than Tc. Inkjet according to 17 or 18
Recording device . 20. The ink jet recording apparatus according to claim 19 , wherein the water-soluble polymer is a polymer having N-alkyl-substituted acrylamide as a monomer unit. 21. The ink jet recording apparatus according to claim 20 , wherein the polymer is a homopolymer. 22. The ink jet recording apparatus according to claim 17, wherein the head portion has a head for ejecting the ink as droplets by applying thermal energy to the ink. 23. A color material and an aqueous liquid medium that dissolves or disperses the color material, has a lower critical co-dissolution temperature (Tc), and changes the temperature from a temperature lower than the Tc to a temperature higher than the Tc. An ink-jet recording method comprising a step of applying an ink-jet ink that causes phase separation to the recording material as a droplet by applying the recording material to the recording material when the droplet of the ink adheres to the recording material. An inkjet recording method comprising heating so as to cause phase separation. 24. A color material and an aqueous liquid medium that dissolves or disperses the color material, has a lower critical co-solubility temperature (Tc), and changes the temperature from a temperature lower than the Tc to a temperature higher than the Tc. An inkjet recording method using an inkjet ink that causes phase separation by causing a droplet of the inkjet recording ink in a uniform state to be applied to a recording medium, and the ink droplet on the recording medium. And an ink jet recording method comprising the step of shifting the phase separation state to the phase separation state.