JP2002249691A - Color ink for electronic blackboard and full color electronic blackboard - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve fixing property in a full color electronic blackboard in which data is written by ink jet. SOLUTION: A color ink for an electronic blackboard has a surface tension γL in a range of γC<=γL<=γC+5 dyne.cm<-1> in a belt shaped recording medium having a critical shearing stress γ of 25-50 dyne.cm<-1> at 25 deg.C. The full color electronic blackboard comprises the recording medium and the ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a full-color electronic blackboard for displaying an image on a whiteboard by ink jet, and can be used for a message board, an advertisement display, and the like.

[0002]

2. Description of the Related Art Electronic blackboards are roughly classified into two types. One is for printing out handwritten characters using a whiteboard marker pen, and the other is for displaying characters output from a computer.

The present invention belongs to the latter, and heretofore, products using a magnestylus or a liquid crystal have been used as products.

[0004] Conventionally, ink-jet recording uses a water-soluble ink, so that paper or a water-soluble polymer has been used as a receptor layer for absorbing liquid.

Conventionally, as electronic blackboards using the ink jet method, Japanese Patent Application Laid-Open Nos. 08-106261 and 08-31
0078 and the like.

[0006]

Since the magnetism stylus reuses a monochrome magnetic material, it is difficult to colorize it. The liquid crystal has problems such as a low contrast, a viewing angle characteristic, and a relatively large power consumption for holding a display due to the necessity of a backlight or lack of memory. When using a recording medium having a receiving layer in an ink jet recording method as an electronic blackboard, it is difficult to reuse the recording medium, and the ink and the recording medium become consumables, and cost and
Maintenance and ecology issues occur.

[0007] In order to reuse a recording medium, it is necessary to achieve both the fixing property to the recording medium without the receiving layer and the releasability from the recording medium. That is, it is necessary to provide a configuration that prevents the recorded image from bleeding because the solvent in the ink exists on the surface of the recording medium and has fluidity. Furthermore, it is necessary that images can be easily and completely erased. JP-A-08-10
6261 and JP-A-08-310078 do not solve this problem.

In spite of solving the problem of compatibility between the fixability and the releasability, ink jetting still requires ejection stability, long-term dispersion stability, and fineness, unlike a white board marker ink. There are many important technical issues such as prevention of solidification due to long-term leaving at the nozzle tip.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a color ink composition for an electronic blackboard and a full-color electronic blackboard. There is a second feature in the configuration of the device for assisting the ink color mixture and the fixability for the development.

FIG. 1 shows the configuration of a full-color electronic blackboard. The full-color electronic blackboard of the present invention is a belt-shaped recording medium,
The apparatus includes at least a recording medium scanning unit, an inkjet head, an inkjet head scanning unit, an ink cartridge, and an ink supply unit.

The recording (display) medium of the electronic blackboard is in the form of a belt (endless or having a winding mechanism at both ends), and the recording surface is preferably white, and a white pigment is mixed with a plastic such as polyethylene terephthalate. Alternatively, an acrylic hard coat, a fluorine coat, a silicone coat, or the like on the front surface, or a layer in which various layers are laminated on the back surface can be used.

The endless belt-shaped recording medium scans the recording medium in a fixed direction by applying tension to the recording medium with at least two rollers and rotating the rollers.

[0013] Since endless belts usually require seamless processing and increase costs, there is also a method in which winding mechanisms are provided at both ends. A tension is applied to the recording medium by two rollers, and the rollers are rotated. And scan the recording medium while winding the belt.

In this case, when the belt is wound, the rollers are reversed to return to the initial state. The arrangement of the ink jet head is preferably a non-display portion in front of the display portion of the electronic blackboard in the above-mentioned scanning direction and a portion where maintenance is easy.

As will be described later, the inkjet head is scanned by the carriage in a direction perpendicular to the scanning direction of the recording medium, that is, in the width direction of the recording medium.

In the present invention, the ink discharged on the surface of the belt-shaped recording medium initially forms dots due to adsorption and wettability (diffusibility) at the solid-liquid interface, and the solvent in the ink such as water or alcohol / glycol. After evaporating, the image is fixed by solid-solid adhesion or the like.

An object of the present invention is to optimize the surface tension between the ink and the recording medium in the initial stage and improve the wettability. Further, for the above-described reason, the surface tension γ _L of the ink changes with time and is not constant due to the temperature and humidity of the environment.
Specify the surface tension at 5 ° C.

Further, in the color ink for electronic blackboard of the present invention, a polymer emulsion is added for securing fixability during and after the evaporation of the ink solvent, and a pigment ink is used for securing releasability. preferable.

The reason why the fixability of the color ink for an electronic blackboard of the present invention is good is presumed as follows. As the polymer emulsion used in the present invention, an acrylic emulsion or a vinyl acetate emulsion in which a water-insoluble polymer is dispersed in a solvent mainly containing water is preferable. When the water-soluble polymer is added to the dye ink, the viscosity increases and the ink cannot be ejected, so that the addition to the inkjet ink is very small.

On the other hand, since an ink having a low viscosity can be obtained even when a high concentration is added to the emulsion, it can be ejected by an ink jet. Immediately after printing, it interacts with and adheres to the hydrophobic surface of the recording medium by viscous and surface tension.

The critical surface tension γ of the recording medium_CIs the molecular chemical structure
Depending on the structure, the smaller the number, the easier it is to repel water,
If it is large, it tends to get wet easily. The recording medium is
Non-permeable materials are common, so that liquids are solid surfaces
The main effect is the extended wetting that spreads the liquid,
Almost no permeation wetting in the pores of the body is observed
No. As a recording medium used for an electronic blackboard, 25NO
To 50 dyne cm ^-1Is generally within the range.

On the other hand, the surface tension γ _L varies depending on pigments, solvents, surfactants, polymer emulsions, additives and the like also used in the ink. Therefore, the present invention is characterized in that the surface tension of the ink is adjusted according to the recording medium used.

In the case of γ _L <γ _C , the ink tends to spread on the recording medium, and a phenomenon called bleeding in which color inks bleed easily occurs. In the opposite case, the ink tends to be repelled.

Therefore, in the present invention, it is preferable that the range of γ _C ≦ γ _L ≦ γ _C +5 dyne · cm ⁻¹ is satisfied in order not to bleed and to be repelled and to obtain an appropriate dot diameter.

When the glass transition point of the polymer emulsion is in the range of about 0 ° C. or less after the above-mentioned initial adsorption, adhesion to the surface of the recording medium acts (under normal use conditions), and the solvent of the ink is dried. To prevent the image from flowing before the operation.

Further, as the solvent evaporates, the emulsion polymer particles come into contact with each other to form a film, thereby increasing the fixing property. This film formation also contributes to peelability.

A second feature of the present invention is that the color ink for electronic blackboard is a pigment ink.

Pigment inks have been conventionally used for markers for whiteboards because of their poor abrasion properties, and can be erased by an eraser for whiteboards. Pigment inks had problems such as dispersion stability and ejection stability for inkjet use, but in the present invention, the dispersibility was improved by adding a polymer emulsion.

Furthermore, in order to stably eject the pigment ink to which the polymer emulsion is added by ink jet, glycol and / or alcohol is added to keep the ink moist before ejection and to readjust the surface tension immediately after printing. Do.

If the amount of glycol is large, the viscosity increases to cause ejection failure or drying on the recording medium to slow down, thus affecting the fixability, and the alcohol amount affecting the surface tension.

Therefore, in the present invention, the pigment concentration related to the image density is 1 to 10% by weight, the polymer emulsion is 0.001 to 0.1% by weight, the glycols are 0 to 10% by weight, and the alcohols are 0 to 10% by weight. From 10% by weight
It is preferable to include at least

Examples of the alkylene glycols in which the alkylene group contains 2 to 6 carbon atoms include ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol and hexylene glycol. , Diethylene glycol and the like.

As alkyl alcohols having 1 to 4 carbon atoms, for example, aliphatic monohydric alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec.
-Butyl alcohol, tert-butyl alcohol and the like.

It is preferable to add glycol or alcohol within the above range. Pigment concentration is yellow, magenta,
The value is set within the above range according to the spectral reflection density and color balance of one of the pigments of cyan and black, and the printing density.

The carbon black used in the black ink is a carbon black produced by a furnace method or a channel method, and has a primary particle diameter of 15 to 40 μm and a BET.
Specific surface area by the method is 50 to 300 square m / g, DB
P oil absorption is from 40 to 150 ml / 100 g, volatile matter is from 0.5 to 10%, pH value is from 2 to 9, for example. 2300, No. 900, MCF88, No
33, No. 40, No. 45, No. 52, MA7, M
A8, No. 2200B (Mitsubishi Chemical), RAVE
N1255 (made in Colombia), REGAL400R, R
EGAL330R, REGAL660R, MOGUL
L (Cabot), Color Black FW
1, COLOR Black FW18, Color
Black S170, Color Black S1
Commercial products such as 50, Printex 35 and Printex U (Degussa) can be used. Further, a prototype newly manufactured for the present invention may be used. Examples of the pigment used for the yellow ink include C.I. I. Pigment Ye
llow1, C.I. I. Pigment Yellow 2, C.I. I. Pigment
Yellow 3, C.I. I. Pigment Yellow 13, C.I. 1. Pigm
ent Yellow 16, C.I. I. Pigment Yellow 83 and pigments used as magenta inks include C.I. I. PIGM
ENT RED5, C.I. I. PIGMENT RED7, C.I. I. PIGMENT
RED12, C.I. I. PIGMENT RED48 (CA), C.I. I.
PIGMENT RED48 (MN), C.I. I. PIGMENTRED57
(CA), C.I. I. PIGMENT RED112, C.I. I. PIGME
NT RED 122, pigments used as cyan inks include C.I. I. PIGMENT BLUE1, C.I. I. PIGMENT BLUE
2, C.I. I. PIGMENT BLUE3, C.I. I. PIGMENT BLUE1
5: 3, C.I. I. PIGMENT BLUE16, C.I. I. PIGMENT
BLUE22, C.I. I. VAT BLUE4, C.I. I. VAT BLUE6 and the like, but those newly manufactured for the present invention can also be used.

The polymer emulsion can be ejected by ink-jet printing, and has a concentration which assists in the fixability of printing and achieves both releasability, and is preferably an acrylic emulsion or a vinyl acetate emulsion.

The raw material of the polymer serving as the skeleton is a vinyl acetate monomer or a (meth) acrylic monomer. For example, vinyl acetate, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate ( n-, i-, t-), hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, N-propyl methacrylate, isopropyl methacrylate, butyl methacrylate (n-, i-, t-), hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, lauryl methacrylate, sulphate methacrylate Allyl, number of carbon atoms of acrylic acid or methacrylic acid cyclohexyl methacrylate 1
Alkyl or cycloalkyl ester of 30; carbon number of acrylic acid or methacrylic acid such as trimethoxybutyl acrylate, trimethoxybutyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate, ethoxybutyl acrylate, ethoxybutyl methacrylate, etc. 2-18 alkoxyalkyl esters;
2-hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, 2-
Examples thereof include hydroxyalkyl methacrylates, hydroxypropyl methacrylates, hydroxybutyl methacrylates, and other hydroxyalkyl esters of acrylic acid or methacrylic acid having 2 to 8 carbon atoms.

In general, the above monomers are often used after being copolymerized at an appropriate composition ratio. In addition, a plurality of polymers obtained by polymerizing the above monomers may be used as a mixture.
When one or more of the above monomers are copolymerized with an anionic monomer, a nonionic monomer, a cationic monomer, or the like, they function as an emulsifier, resulting in improved dispersion stability, and a dispersant such as a surfactant or a water-soluble polymer. It is preferable because the density can be reduced, and there are effects such as an increase in ink jet ejection characteristics and fixability to a recording medium.

Examples of the anionic monomer include acrylic acid, methacrylic acid, maleic anhydride, itaconic acid and sodium styrenesulfonate.

Examples of the nonionic monomer include styrene monomers, acrylonitrile, hydroxyalkyl (meth) acrylate, vinyl acetate, alkyl vinyl ethers, and (meth) acrylates.

Examples of the cationic monomer include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, vinylimidazole, vinylpyridine, vinylpyrrolidone, vinylsuccinimide, and the like, or quaternized products thereof. Is mentioned.

Further, crosslinking monomers such as divinyl compounds, polyvalent acrylate compounds, diene compounds, (meth) acrylates containing dihydrodicyclopentadienyl groups and ethylenically unsaturated compounds containing epoxy groups,
A crosslinker such as an aziridine crosslinker, a block type or self-emulsifying type isocyanate crosslinker, a carbodiimide crosslinker, and a metal crosslinker may be used. If necessary, an antioxidant, a light stabilizer, a preservative, a coloring agent, and the like may be added. In preparing the emulsion, an emulsifier may be used. The emulsifier is not particularly limited, for example, dodecylbenzene sulfonates, alkyl sulfates, anionic emulsifiers such as polyoxyethylene alkyl phenyl ether sulfonates, polyoxyethylene alkyl phenyl ether, polyoxyethylene Nonionic emulsifiers such as alkyl ethers are exemplified.

A tackifier resin may be added.
Gum rosin, tall oil rosin, wood rosin, polymerized rosin, hydrogenated rosin, disproportionated rosin, rosin ester, polymerized rosin ester, hydrogenated rosin ester, disproportionated rosin ester, rosin-modified tackifying resin such as rosin-modified phenolic resin, Terpene resin, hydrogenated terpene resin, phenol resin, terpene phenol resin, hydrogenated terpene phenol resin, xylene resin, aliphatic petroleum resin, alicyclic petroleum resin, aromatic petroleum resin, cumarone resin, styrene resin, etc. Is mentioned.

As described above, a polymer contained in a polymer emulsion having a low glass transition point has tackiness and good fixability to a recording medium. Therefore,
In the present invention, the polymer (copolymer having the above composition) contained in the polymer emulsion to be added to the ink preferably has a glass transition temperature of 0 ° C. or lower as measured by a scanning differential thermal analyzer.

Although the above-mentioned polymer emulsion functions as a dispersant for the pigment, it is preferable to use a surfactant or a water-soluble resin as the dispersant.

As the pigment dispersant used in the present invention, any water-soluble resin can be used, but the weight average molecular weight is preferably in the range of 1,000 to 30,000. further,
Preferably, it is in the range of 3000 to 15000. Specifically, styrene, styrene derivatives, vinylnaphthalene, vinylnaphthalene derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acids, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid , Itaconic acid derivatives, fumaric acid, block copolymers comprising at least two or more monomers selected from fumaric acid derivatives, graft copolymers, or random copolymers, and salts thereof. Can be These resins are alkali-soluble resins that are soluble in an aqueous solution in which a base is dissolved. Further, a homopolymer composed of a hydrophilic monomer or a salt thereof may be used. Also,
Polyvinyl alcohol, carboxymethyl cellulose,
It is also possible to use a water-soluble resin such as a naphthalenesulfonic acid formaldehyde condensate. However, when an alkali-soluble resin is used, there is an advantage that the viscosity of the dispersion can be reduced and the dispersion is easy. further,
A resin that starts to aggregate at a pH of 6 or less is particularly preferable for improving the print density. Preferably, the water-soluble resin is contained in the range of 0.1 to 5% by weight based on the total amount of the recording liquid. Since the water-soluble resin is dispersed in the pigment ink, it has a lower viscosity than when it is added to the dye ink, and can be ejected by inkjet.

Further, in the recording liquid of the present invention, preferably, the recording liquid as a whole is adjusted to be neutral or alkaline, so that the solubility of the water-soluble resin is improved, and the recording liquid is further excellent in long-term storage. It is desirable because it can be liquid.
However, in this case, it may cause corrosion of various members used in the ink jet recording apparatus, so that the pH is preferably in the range of 7-10.

Examples of the pH adjuster include various organic amines such as diethanolamine and triethanolamine; inorganic alkali agents such as hydroxides of alkali metals such as sodium hydroxide, lithium hydroxide and potassium hydroxide;
Organic acids and mineral acids can be mentioned. As described above, the pigment and the water-soluble resin are dispersed or dissolved in the aqueous liquid medium.

The aqueous liquid medium suitable for the ink of the present invention is a mixed solvent of water and a water-soluble organic solvent. The water is not general water containing various ions, but deionized water (deionized water). It is preferred to use In addition, a polyhydric alcohol and / or its alkyl ether may be added.

The polyhydric alcohols and / or alkyl ethers thereof used in the present invention include polyalkylene glycols such as polyethylene glycol and polypropylene glycol; glycerin; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, And lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether.

Examples of the surfactant include anionic surfactants such as fatty acid salts, higher alcohol sulfates, liquid fatty oil sulfates, alkyl allyl sulfonates, polyoxyethylene alkyl ethers, and polyoxyethylene alkyl esters. And nonionic surfactants such as polyoxyethylene sorbitan alkyl esters, and one or more of these can be appropriately selected and used. The amount used is desirably 0.01 to 5% by weight based on the total amount of the ink. At this time, it is preferable to determine the amount of the surfactant to be added so that the surface tension of the ink is 30 dyne / cm or more. This is because the fact that the surface tension of the ink shows a value smaller than this value means that in the ink jet recording system of the present invention, the printing due to the wetting of the nozzle tip (deviation of the landing point of the ink droplet) and the like.
This is because it causes an undesirable situation.
Examples of the pH adjuster include various organic amines such as diethanolamine and triethanolamine, inorganic alkali agents such as hydroxides of alkali metals such as sodium hydroxide, lithium hydroxide and potassium hydroxide, organic acids and mineral acids. Acids.

(Appendix: Since the critical surface tension of the recording medium used in the present invention is 25 dyne / cm or more, if the surface tension of the ink is 30 dyne / cm, claim 1 is satisfied.) Interface added to ink for ink jet Examples of the activator include the following.

Compound Group A: A-1: Ethylene glycol mono n-butyl ether A-2: Ethylene glycol monophenyl ether A-3: Ethylene glycol monoisobutyl ether A-4: Diethylene glycol mono n-butyl ether A-5: Diethylene glycol mono Hexyl ether A-6: diethylene glycol monoisobutyl ether A-7: triethylene glycol n-butyl ether A-8: dipropylene glycol monopropyl ether A-9: ethylene oxide adduct of benzyl alcohol Compound group B: B-1: acetylene glycol B-2: Ethylene oxide-propylene oxide-ethylene oxide (bruronic type) surfactant B-3: Ethyl alcohol of higher alcohol Renoxide adduct Compound group C: C-1: a compound represented by the following general formula

[0054]

Embedded image

(Where k is from 3 to 50 and m is from 3 to 2)
5, n is 3 to 25, and m + m is 6 to 50. C-2: a compound represented by the following general formula

[0056]

Embedded image

(Where k = 20 to 50 and m is 10
-25, n is 10-25, and n + m = 20-
50 and p is 2-5. The main components constituting the ink used in the present invention are as described above, but if necessary, use urea, a water-soluble organic solvent, a pH adjuster (described above), an antifoaming agent, a preservative, and the like. Is also good. Usable water-soluble organic solvents include amides such as dimethylformamide and dimethylacetamide; ketones and ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; N-methyl-2-pyrrolidone; , 3-dimethyl-2-imidazoidinone and the like.

The following is an example of a method for preparing the ink used in the present invention. 70 water-soluble resin and distilled water
Heat to ° C. to completely dissolve the resin. At this time, if the concentration of the resin to be dissolved is low, the resin may not be completely dissolved. Therefore, when dissolving the resin, a high-concentration solution may be prepared in advance and diluted to prepare a desired resin solution. A pigment and an aliphatic monohydric alcohol (such as ethanol) are added to the solution, premixed, and then subjected to a dispersion treatment.
As the dispersing machine used for the dispersion treatment, any commonly used dispersing machine may be used, and examples thereof include a ball mill using ceramic balls and steel balls, a roll mill, a sand mill using glass beads and ceramic beads, and the like. Can be Among these, a high-speed sand mill is preferable, for example, a super mill, a sand grinder, a bead mill, an agitator mill, a Glen mill,
Dyno mill, pearl mill, Kobol mill (all are trade names) and the like. As beads used in the sand mill, glass beads, ceramic beads, zirconium beads, and the like having a size of 1 mm to 1.5 mm are used.

As an example of the conditions for preparing the ink dispersion used in the present invention, the following conditions are preferred. -Dispersing machine: sand grinder (made by Igarashi Kikai)-Grinding media: glass beads or zirconium beads 1mm diameter-Filling rate of grinding media: 50% (volume)-Grinding time: 3 to 4 hours Further, centrifugation treatment (12, 000 RPM, 15-20
Min) to remove coarse particles and reduce the particle size to 100 nm or more.
Make a 200 nm dispersion. In addition, as a dispersing machine, a pearl mill (manufactured by Ashizawa, discharge speed: 100 ml /
Minutes) may be used.

It is desirable that the total amount of the pigment and the water-soluble resin in the dispersion is 5 to 30% or more, preferably 10 to 30% or less on a weight basis. The reason for this is that if the pigment and the water-soluble resin do not exist at a certain concentration or more in the dispersion, the dispersion can be performed efficiently and an optimum dispersion state cannot be obtained. Next, this dispersion is mixed with a polymer emulsion, a water-soluble organic solvent, ion-exchanged water and the like, and stirred for 1 hour to obtain an ink. Methods for obtaining a pigment having a desired particle size distribution include reducing the size of the pulverizing media of the disperser, increasing the filling ratio of the pulverizing media, increasing the processing time, reducing the discharge speed, and using a filter after pulverization. A method such as classification using a centrifuge is used.
Alternatively, a combination of these methods may be used.

In addition to the above-described ink preparation method, the pigment can be dispersed with a surfactant instead of the water-soluble resin.

Instead of mixing a polymer emulsion with a pigment dispersion, a raw material monomer may be mixed with a pigment dispersion and polymerized by stirring to obtain a pigment ink.

As a recording apparatus suitable for use in the present invention, there is an apparatus which applies thermal energy corresponding to a recording signal to ink in a chamber of a recording head and generates droplets by the energy. FIG. 2 shows an example of the configuration of a head, which is a main part thereof. The head 13 includes a glass, ceramic, or plastic plate having a groove 14 through which ink passes, and a heating head 14 used for thermal recording (a thin film head is shown in the figure, but is not limited to this). And obtained by bonding. The heating head 15 includes a protective film 16 made of silicon oxide or the like, aluminum electrodes 17-1 and 17-2, a heating resistor layer 18 made of nichrome or the like, a heat storage layer 19, and a substrate having good heat dissipation properties such as alumina. It consists of twenty. The ink 21 reaches a discharge orifice (micropore) 22 and is subjected to a meniscus 23 by a pressure P.
Is formed. Now, when an electric signal is applied to the electrodes 17-1 and 17-2, the area of the heating head 15 indicated by n rapidly generates heat, bubbles are generated in the ink 21 in contact with the area, and the meniscus 23 is generated by the pressure. Protrudes and the ink 21
Is ejected and becomes a recording droplet 24 from the orifice 22 and flies toward the recording medium 25. FIG. 3 shows an external view of a multi-head in which many heads shown in FIG. 2 are arranged. The multi-head is formed by bonding a glass plate 27 having a multi-groove 26 and a heating head 28. FIG. 2A is a cross-sectional view of the head 13 along the ink flow path.
FIG. 2B is a tangent cross section taken along line AB in FIG.

FIG. 5 shows an example of an ink jet recording apparatus incorporating the head according to the present invention. In FIG. 4, reference numeral 61 denotes a blade serving as a wiping member, one end of which is held by a blade holding member and serves as a fixed end in the form of a cantilever. The blade 61 is disposed at a position adjacent to a recording area of the recording head, and in this example, is held in a form protruding into the movement path of the recording head. 6
Reference numeral 2 denotes a cap, which is disposed at a home position adjacent to the blade 61 and has a configuration in which the cap moves in a direction perpendicular to the direction in which the recording head moves to abut on the ejection surface to perform capping. It is an ink absorber provided adjacently and, like the blade 61, is held in a form protruding into the movement path of the recording head. The blade 61, the cap 62, and the absorber 63 constitute an ejection recovery section 64, and the blade 61 and the absorber 63 remove moisture, dust, dust, and the like on the ink ejection port surface. Reference numeral 65 denotes a recording head which has ejection energy generating means and discharges ink on a recording material facing the ejection port surface where ejection ports are arranged to perform recording, and 66 denotes a mounting of the recording head 65 and movement of the recording head 65. Is a carriage for performing the following.
The carriage 66 is movably engaged with the guide shaft 67,
A part of the carriage 66 is connected (not shown) to a belt 69 driven by a motor 68. 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.

FIG. 4 shows an ink cartridge 4 containing ink supplied to the head via an ink supply tube.
FIG. 5 is a diagram showing an example of a fifth example. Here, reference numeral 40 denotes an ink bag containing the supply ink, and a rubber stopper 4 is provided at the tip thereof.
2 are provided. By inserting a needle (not shown) into the stopper 42, the ink in the ink bag 40 can be supplied to the head. 44 is an ink absorber for receiving the discharged ink. 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 separated as described above, and the one in which they are integrated as shown in FIG. 5 is also suitably used.

In FIG. 5, reference numeral 70 denotes an ink jet cartridge, which contains an ink absorber impregnated with ink, and in which ink in the ink absorber is supplied from a head unit 71 having a plurality of orifices. It is configured to be ejected as ink droplets. Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the cartridge with the atmosphere. This ink jet cartridge 70 can be used in place of the recording head 65 shown in FIG.
It is detachable from the carriage 66.

Next, the present invention is a full-color electronic blackboard in which an image is formed using four types of color inks of yellow, magenta, cyan and black. The color ink of each color is supplied from a separate ink cartridge to a recording head corresponding to each color.

In the present invention, as described above, a polymer emulsion is added to improve the fixing property of the ink.

First, an ink cartridge containing the pigment color ink for an electronic blackboard, a belt-shaped recording medium, a recording medium scanning unit, an ink jet head, an ink jet head scanning unit, and an ink supply unit are provided. The direction is perpendicular to the inkjet head scanning direction, and when one of them is scanning, one is stopped.

In the conventional electronic blackboard, the liquid crystal does not scan the recording and display medium but has an address by electric wiring, and the magnet stylus only scans the recording medium.

Next, in the above-described apparatus configuration, the ink jet heads of four colors are integrated, and the arrangement of each color is the same as the scanning direction of the recording medium.

Although the recording heads of the respective colors are also integrated in the ordinary ink jet apparatus, the arrangement is arranged in a line in the scanning direction of the recording heads, so that the recording heads of the respective colors are scanned in a short time. Overprinted. The reason for this arrangement is that the ink dot registration accuracy, the miniaturization of the device, and the absorption of the ink solvent are fast and bleed because of printing on paper used for ordinary ink jet and on permeable recording media with an ink receiving layer. This is because there is no problem, and furthermore, since a dye is used, if another color is superimposed and printed on the previously printed and dried color, the dye is eluted and the result is equivalent to the case of printing without drying.

In the present invention, since a non-permeable recording medium is used, a time lag until drying is necessary. On the other hand, the size and resolution are not required as much as a usual ink jet apparatus. In addition, the pigment ink has high water resistance after drying, so that overprinting is possible.

Hereinafter, this embodiment will be described in detail.

[0075]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Example 1 (Preparation of Pigment Dispersion) Styrene-acrylic acid-butyl acrylate copolymer 1.5 parts (acid value 116, weight average molecular weight 3700) monoethanolamine 1 part 81.5 parts of exchanged water 5 parts of diethylene glycol The above components were mixed and heated to 70 ° C. in a water bath.
Dissolve the resin completely. Carbon black (MCF88 manufactured by Mitsubishi Kasei) 10 newly produced in this solution
And 1 part of isopropyl alcohol, and after premixing for 30 minutes, dispersion treatment was performed under the following conditions.

Dispersing machine Sand grinder (made by Igarashi Kikai) Grinding media Zirconium beads 1 mm diameter Filling rate of grinding media 50% (volume) Grinding time 3 hours Further centrifugation (12,000 RPM, 20 minutes)
To remove coarse particles to obtain a dispersion.

(Preparation of Ink) 10 parts of the above dispersion 10 parts of Teisan Resin 370N 0.1 part 15 parts of diethylene glycol 5 parts of N-methylpyrrolidone 3 parts of isopropyl alcohol 65 parts of ion-exchanged water The above components were mixed, and the pH was adjusted with monoethanolamine. Adjusted from 8 to 10 and as a surfactant

[0078]

Embedded image

The surface tension was adjusted with (n + m = 20, p = 5, k = 20, a 50% methanol solution of a compound having a molecular weight of about 2500) to obtain a black ink.

(Yellow Ink) In the above formulation, the pigment carbon black was replaced with C.I. I. Pigment Yellow 13 except that Pigment Yellow 13 was used.

(Magenta Ink) In the above formulation, the pigment carbon black was replaced with C.I. I. A magenta ink was prepared in the same manner except that Pigment Red 7 was used.

(Cyan Ink) In the above formulation, the pigment carbon black was replaced with C.I. I. A cyan ink was prepared in the same manner except that Pigment Blue 22 was used.

In this embodiment, a white PET film containing titanium oxide as a belt-shaped recording medium had a critical surface tension γc at 25 ° C. of 45 dyne · cm ⁻¹ .

The surface tension γ _{L at} 25 ° C. of the ink prepared above is

[0085]

[Table 1]

Was as follows.

(Example 2) An electronic blackboard device for printing and recording while carrying a belt-shaped recording medium between two rollers and rotating the rollers was manufactured using an ink-jet cartridge of Canon BJF-8500 and cartridge scanning means. .

[0088]

When printing was performed using the ink described in Example 1, good printing results were obtained for both characters and pictures, and they could be completely erased with a commercially available marker pen eraser.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a display device according to a first embodiment.

FIG. 2 is a sectional view of a configuration of a head for ejecting ink.

FIG. 3 is an external view illustrating a multi-head in which a number of heads in FIG. 2 are arranged.

FIG. 4 is a cross-sectional view of the configuration of an apparatus for performing the inkjet recording method of the present invention.

FIG. 5 is a perspective view illustrating a recording apparatus in which a head and an ink cartridge are integrated.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Display apparatus 3 Display sheet 7 Printer 13 Head 14 Groove 15 Heating head 16 Protective film 17-1, 17-2 Aluminum electrode 18 Heating resistor layer 19 Heat storage layer 20 Substrate 21 Ink 22 Discharge orifice 23 Meniscus 24 Recording droplet 25 Cover Recording medium 26 Multi-groove 27 Glass plate 28 Heating head 4O Ink bag 42 Plug 44 Ink absorber 45 Ink cartridge 51 Paper feed unit 52 Paper feed roller 53 Discharge roller 61 Blade 62, 62 'Cap 63 Ink absorber 64 Ink recovery unit 65 Head on which aqueous pigment ink is mounted 65 'Head on which liquid containing fine particles and a binder polymer is mounted 66 Carriage 67 Guide shaft 68 Motor 69 Belt 70 Inkjet cartridge 71 Head section 72

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B41J 3/04 101Z

Claims (2)

[Claims] 1. Among yellow, magenta, cyan and black
Low color pigments, glycols and alcohols
Using color ink for electronic blackboards characterized by including
To record on a belt-shaped recording medium by inkjet
Belt-like notes at 25 ° C on a rucolor electronic blackboard
Critical surface tension γ of recording medium_CIs 25 to 50 dyne cm
^-1And the ink surface tension γ_LIs γ_C≤γ_L≤γ_C+ 5dyne
・ Cm ^-1Color for an electronic blackboard, characterized by being in the range of
-Ink. 2. The full-color electronic blackboard according to claim 1, wherein said belt-shaped recording medium and ink are used.