JP2002206063A - Ink and image recording and displaying device using the ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink for ink jet image recording and displaying device capable of preventing dyeing on a recording medium and having improved erasability and releasablity and to provide an image recording display device. SOLUTION: This ink is an ink for ink jets containing a pigment and a colloidal silica and characterized in that the size of the particles of the pigment is the same as or larger than that of the colloidal silica particles. The image recording and displaying device is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording and display apparatus having an ink, an ink jet recording means using the ink, and an erasing means for erasing an image recorded on a recording medium writable by the ink jet recording means. Related to the device.

[0002]

2. Description of the Related Art Generally, image display devices include devices mainly for displaying moving images, such as CRTs and liquid crystal displays, which are display devices such as computers. On the other hand, there is a display device that repeatedly displays and deletes a large-screen still image like a poster or a bulletin board. An example of this display device is an information board that displays destinations and information in a station yard. Further, as a similar device, there is an electronic blackboard used for a meeting or a meeting.

In recent years, an increase in paper consumption and an increase in power consumption for image display have become problems in terms of resource saving and environmental destruction. In order to solve these problems, there is a need for the latter still image display device which consumes less power and drastically reduces paper consumption. Conventional moving image display device C
RTs and liquid crystal displays have a problem that the device price is high when the size is large. Further, since power is used to maintain the display state even when a still image is displayed for a long time, there are many problems in terms of power consumption. Recently, many large and low power consumption type display devices such as a plasma display (PDP) have been developed and commercialized. However, they are still expensive, and are display devices considering moving image display like a CRT. It is not suitable for displaying images for a long time.

As a display device for recording and erasing a still image display on the same recording medium, an electrostatic latent image corresponding to an image signal is recorded on a special recording medium from a computer or the like, developed by magnetic toner, and displayed. An information board has been commercialized. If the electrostatic image on the recording medium is removed, the image adhered and developed on the special recording medium is removed,
It is possible to record a new image repeatedly. The only problem with this information board is that it is difficult to colorize it because it uses magnetic toner.

[0005] On the other hand, although the method of use and purpose are different from those of the above-described display device, a handwritten still image (character) is displayed, the displayed content is read by a scanner, a hard copy is taken, and then the recorded image is recorded. There is an electronic blackboard device as a device for erasing a still image with a blackboard eraser. This device is useful in terms of reducing paper consumption and power consumption. However, there is no product which is connected to a computer or the like, does not record and display a still image, and further automatically erases a written image.

[0006] The development of electronic blackboard devices with image erasures has been carried out conventionally. For example, JP-A-61-9071, JP-A-5-597, JP-A-5-14564, and JP-A-5-14564. -160940, JP-A-5-16
2494, JP-A-6-32095, JP-A-6-48091, JP-A-6-87295,
A proposal as disclosed in JP-A-6-245008 has been made. According to these inventions, a character or an image handwritten by a writing instrument for a conventional electronic blackboard on a recording medium of a conventional electronic blackboard is transferred to an electrophotographic photosensitive member cleaning apparatus used in a copying machine such as a cleaning fur brush or a rubber blade. An apparatus for wiping and erasing by a similar method has been proposed. However, with respect to the image writing section, the writing operation is only performed by handwriting with a writing instrument as in the related art.

The requirements for a still image information display device are as follows:
It has a function as a display device in a network instead of a device that only exists in a conference room as a stand-alone like an electronic blackboard, and can display information from a remote place sequentially. It is hoped that it can be displayed at the place. In a conventional image display device,
The only device that can perform writing and erasing based on information from the external image input device is a magnetic recording type information board. However, colorization is difficult because magnetic toner is used, and an image display device capable of displaying a color image and recording and displaying a high-quality image has been desired.

Accordingly, the present inventors mounted an ink jet recording apparatus on a recording medium similar to an electronic blackboard as a system capable of displaying a color image, performed image writing on the recording medium, and then performed display. A prototype of an image recording and display device capable of erasing an image by an erasing method was studied. The ink jet recording method is to fly a small droplet of ink,
The recording is performed by attaching ink to a recording medium such as paper.

When ink-jet recording is performed on a recording medium similar to a conventional electronic blackboard, it has been impossible to write and record using conventional ink-jet inks.
In general, as a recording medium used for an electronic blackboard, a sheet in which a fluorine compound-based or acrylic compound-based film or the like is stuck on a milky white base film or the surface is coated is used. When writing an image on the blackboard with a blackboard pen using oil-based ink, the solvent evaporates and then the release agent and the resin film containing the pigment remain, and therefore, cloth, felt,
It is configured to be easily wiped and erased with a sponge or the like.
In addition, the surface tension of the recording medium surface is set small so as to facilitate erasing.

Therefore, when recording is performed using the aqueous ink for ink jet, the ink is repelled on a conventional recording medium for an electronic blackboard, and there is a problem that image recording cannot be performed. Further, if the surface tension of the recording medium is made larger than that of the conventional one, there has been a problem that an erasing device such as a blade cannot perform sufficient erasing. Inks used in the inkjet recording method are classified into aqueous and non-aqueous. Generally, the aqueous system contains water as a main component and further contains a water-soluble high-boiling solvent such as glycol for the purpose of preventing drying and preventing nozzle clogging.

As a means for fixing ink on a non-permeable recording medium, a method using an adhesive ink set has been proposed. Examples of the adhesive ink set include aqueous inks containing pigments, resin dispersants, adhesive polymer emulsions, glycols, and the like. Before the ink is ejected, the emulsion is in a dispersed state and has a low viscosity, and after the ejection, it is aggregated and formed into a film and fixed. In addition, if it is a non-aqueous ink, the same quick-drying ink as the conventional marker pen for whiteboard can be used, and the fixing property and the peeling property are improved. Examples of the non-aqueous solvent used for the non-aqueous inkjet ink include hydrocarbons (such as liquid paraffin), alcohols (such as methyl alcohol, ethyl alcohol, and propyl alcohol), phenols, pyrrolidones, and ester solvents. Can be

In the above non-aqueous ink, if the quick-drying property is too high, the ink density will increase before ejection, causing problems such as nozzle clogging. Examples of non-aqueous solvents with slightly reduced drying properties include, for example, alkyl ethers of (mono, di, tri, tetra) alkylene glycols, for example, ethylene glycol monoalkyl ether, diethylene glycol monoalkyl ether, triethylene glycol monoalkyl ale, propylene glycol Monoalkyl ether, tripropylene glycol monoalkyl ether,
Examples thereof include the above-mentioned alkyl ether acetates and pyrrolidones of alkylene glycols such as alkylene glycol, and 2-pyrrolidone, N-methylpyrrolidone, and mixtures thereof.

[0013]

Conventionally, color dyes and color pigments used in ink-jet recording means are adsorbed or reacted with a non-permeable recording medium, and the dyeing becomes strong over time, making it difficult to erase. There was a point. Dyeing is also observed in pigments used for whiteboard marker pens, and it is customary to add a surfactant to ink to improve erasability. Inkjet inks are more restrictive than whiteboard marker pens and cannot be used as is. In other words, the type and amount of the surfactant that can be used are limited because the influence on the ink droplet formation by the piezoelectric element or the heater element or the meniscus formation on the nozzle surface is affected in the ink for ink jet.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ink for an ink jet image recording and display apparatus which prevents dyeing on a recording medium and has improved erasability. The present invention not only provides an image recording and display device for the purpose of reducing power consumption and saving resources than a conventional display device, but also provides a high-quality color image display, and further supports a network. It is an object of the present invention to provide an image recording and displaying device capable of forming a system. Furthermore, in order to achieve the above object, the conventional ink jet recording means (image recording apparatus) is improved to solve the above-mentioned problems which were impossible with the conventional ink jet recording means, and to record the data on a display recording medium. It is an object of the present invention to provide an image recording and display device which can easily erase an image with an erasing member after displaying the image.

[0015]

The above object is achieved by the present invention described below. That is, the present invention is an ink-jet ink containing a pigment and colloidal silica,
An ink characterized in that the size of the pigment particles is the same as or larger than the size of the colloidal silica particles. The average particle size of the pigment and colloidal silica is 20
It is preferred that it is in the range of １００100 nm.

Further, the present invention provides an image recording and displaying apparatus having an image forming means using the above-mentioned ink. The image recording and displaying device is an image recording and displaying device having an ink jet recording means and having an erasing means, and the ink used in the ink jet recording means is preferably the ink of the present invention.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to preferred embodiments. The pigment used in the ink of the present invention is a pigment used in a general inkjet ink, and has four colors of yellow, magenta, cyan, and black. Generally, the black pigment is an inorganic carbon black, and various pigments such as a particle size and physical properties can be obtained depending on a production method or a surface treatment method. Pigments of a color other than black are organic substances, and may be adsorbed on a non-permeable recording medium or reacted and dyed.

In order to prevent the dyeing of the pigment, it is important that the pigment does not come into direct contact with the recording medium, and a substance such as a surfactant may be interposed between the pigment and the recording medium. As a result of our intensive research, we found that the right particle size, the right amount ratio,
It has been found that colloidal silica having appropriate physical properties has an effect of enclosing the pigment particles and physically preventing the pigment particles from contacting the recording medium. The colloidal silica referred to in the present invention is amorphous silica particles composed of silicic acid or silicic acid compounds (including silicates and silicates) dispersed colloidally in a liquid mainly containing water as a main component.

The particle size of the colloidal silica has an optimum value from the viewpoint of dispersion stability in the ink and fixing and releasing properties of the ink. When the particle size is large, sedimentation tends to occur in the ink, and the dispersion stability generally deteriorates. However, when the particle size is too small, aggregation occurs, and the dispersion stability deteriorates. When the particle size is small, the fixability is improved by the effect of filling the gap between the recording medium and the pigment, and the releasability of the recorded image is deteriorated. Furthermore, in order for the colloidal silica to include the pigment, the ratio between the two is important, and there is an optimum range. For the same reason, the physical properties of colloidal silica also have an optimum range.
The average particle size of the colloidal silica used in the present invention is preferably in the range of 20 to 100 nm, and particularly preferably in the range of 50 to 100 nm from the viewpoint of the releasability of the recorded image.

The pigment used in the present invention has an average primary particle diameter of preferably from 20 to 100 nm. In the case of a color pigment, it is particularly preferably from 50 to 100 nm.
nm. For this reason, it is preferable that the primary pigment particles and the colloidal silica have the same particle size, and the particle size of the pigment is larger than that of the colloidal silica.

As described above, according to our intensive studies, when the pigment particles are in direct contact with the recording medium when printed, the wiping properties of the recorded image are poor, and the colloidal silica is in direct contact with the recording medium. It was found that the wiping property of the recorded image was improved when the image was wiped.

FIGS. 8 (a), 8 (b) and 8 (c) show scanning electron micrographs of the printed ink having good wiping properties, and FIGS. 9 (a), 9 (b) and 9 (c) show the wiping properties. 1 shows a scanning electron micrograph of a print with poor ink quality. The observation was performed using an S-5000H field emission scanning electron microscope (FE-SEM) manufactured by Hitachi, Ltd., and all observation conditions were an acceleration voltage of 1.5 kV, a sample inclination of 40 °, and no sample evaporation. 8 (a) and 9 (a) are 10,000 times, FIGS. 8 (b) and 9 (b) are 30,000 times, and FIG.
(C) and FIG. 9 (c) each show 100,000 times FE-SE.
It is an M image. 8 and 9, 111, 113, 11
5, 121, 123 and 125 are pigment particles, and 11
2, 114, 116, 122, 124 and 126 are colloidal silica particles. As can be seen from these photographs, the wiping performance is determined by whether or not the pigment particles are in direct contact with the recording medium.

Therefore, we have considered that the positional relationship between the colloidal silica particles and the pigment particles when printing is important. In short, it has been found that the relationship between the colloidal silica particles and the pigment particles should be designed so that the colloidal silica particles are arranged in the lower layer and the pigment particles are arranged in the upper layer on the recording medium when printed. As the method, it is necessary that the pigment particles do not enter under the colloidal silica particles, that is, the colloidal silica particles ≦ the pigment particles.

As described above, if the pigment particles are equal to or larger than the colloidal silica particles, the percentage of the pigment particles that come into direct contact with the recording medium during printing is the opposite. The particle size is reduced as compared with the case where the particle size is smaller than the particle size of the colloidal silica. That is,
By using the ink jet recording means using the above-described ink, the problem of dyeing in the conventional recording method can be solved, and high-quality printing / erasing on a recording medium can be repeated.

In addition, in order for the colloidal silica to contain the pigment, the ratio between the two is important.
The pigment is used in an amount of 2% by weight to 10% by weight of the ink based on the concealing rate of the printed image.
% By weight, particularly preferably between 5% and 8% by weight. As a result of studying the amount of colloidal silica added, it is preferably 2% by weight to 20% by weight of the ink, and particularly preferably 5% by weight to 15% by weight of the ink from the viewpoint of releasability. The inside of the colloidal silica is made of Si-O-Si, and the surface is made of -SiOH groups. The balance between hydrophilicity and hydrophobicity differs depending on the density and the density ratio.

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). ) Is preferred. As the water-soluble solvent, for example, alcohol, glycol, glycerin and the like are preferable, and glycol is particularly preferable in terms of compatibility between moisture retention and drying. In addition, a polyhydric alcohol and / or its alkyl ether may be added. 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, triethylene glycol And lower alkyl ethers of polyhydric alcohols such as monomethyl (or ethyl) ether.

When the ink of the present invention is used in the image recording and displaying apparatus of the present invention, it is preferable to add a polymer emulsion to the ink in order to secure the fixability of the ink to a recording medium. 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 a water-soluble polymer is added to the ink, the viscosity of the ink increases, and the ink cannot be ejected. On the other hand, an emulsion can be ejected by inkjet because an ink having a low viscosity can be obtained even when a high concentration is added.

Further, by the addition of the polymer emulsion, the ink easily interacts with and adheres to a hydrophobic surface of a recording medium described later immediately after printing. This adsorption power is extremely weak,
When the glass transition point of the polymer emulsion is in the range of about 0 ° C. or less (under ordinary use conditions), the adhesive force to the recording medium surface acts, and the ink image flows before the solvent of the ink dries. To prevent Further, as the solvent evaporates, the emulsion polymer particles come into contact with each other to form a film, thereby increasing the fixability of the ink image. This film formation also contributes to the releasability of the ink image.

The polymer emulsion is preferably an acrylic emulsion or a vinyl acetate emulsion having a concentration capable of being ejected by ink-jet, assisting in fixing the print, and achieving both releasability. 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 (meth) acrylate, ethyl (meth) acrylate, n (meth) acrylate
-Propyl, isopropyl (meth) acrylate, butyl (meth) acrylate (n-, i-, t-), (meth)
Hexyl acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, etc. Acrylic acid or methacrylic acid having 1 to 1 carbon atoms
30 alkyl or cycloalkyl esters;
C2 of acrylic acid or methacrylic acid such as trimethoxybutyl (meth) acrylate, trimethoxybutyl (meth) methacrylate, and methoxyethyl (meth) acrylate
To 18 alkoxyalkyl esters; and hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate having 2 to 8 carbon atoms.

In general, the above-mentioned monomers are often used after being copolymerized at an appropriate composition ratio. Also, a plurality of polymers obtained by polymerizing the above monomers may be mixed and used. Further, an anionic monomer,
As a result of copolymerization of nonionic monomers, cationic monomers, and the like, the copolymer functions as an emulsifier, the dispersion stability of the emulsion is improved, and the concentration of a dispersant such as a surfactant or a water-soluble polymer can be reduced. In addition, there are effects such as an increase in ink jet ejection characteristics and fixability to a recording medium, which is preferable.

Examples of the monomer having an anionic property include acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, sodium styrenesulfonate and the like. Nonionic monomers include, for example, styrene monomers, acrylonitrile hydroxyalkyl (meth) acrylate, vinyl acetate, alkyl vinyl ethers,
(Meth) acrylates.

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

Further, crosslinking monomers such as divinyl compounds, polyvalent (meth) 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 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 above 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.

The method of polymerizing the monomer and the like is preferably an emulsion polymerization method, and the polymerization initiator used is not particularly limited. Examples thereof include persulfates such as potassium persulfate and ammonium persulfate, and azobiscyanovalerin. A redox-based polymerization initiator using a water-soluble azo compound such as an acid, hydrogen peroxide or the like and a reducing agent in combination is exemplified. The amount of the polymerization initiator is based on 100 parts by weight of the one or more monomers.
It is about 0.01 to 1 part by weight. The weight average molecular weight of the obtained polymer is preferably in the range of tens of thousands to hundreds of thousands because it has appropriate tackiness.

As described above, those having a low glass transition point of the polymer contained in the polymer emulsion have tackiness and good fixability of the ink to the recording medium.
Therefore, in the present invention, it is preferable that the glass transition temperature of the polymer (copolymer having the above composition) contained in the polymer emulsion to be added to the ink measured by a scanning differential thermal analyzer is 0 ° C. or less.

Examples of commercially available polymer emulsions having a glass transition temperature of 0 ° C. or lower include NX148 (-49 ° C.) and NX149 (-4
5 ° C), SK Dyne AN49B (-48 manufactured by Soken Chemical)
C), SK Dyne E03H (-69 C), SK Dyne R
E330 (-78 ° C), Teisan Chemical Industry A3611 (-32 ° C), Teisan Resin NFA369
TB (-35 ° C), Teisan Resin NFA370N (-
32 ° C.).

The above-mentioned polymer emulsion also functions as a pigment dispersant, but in the ink of the present invention, it is preferable to use a surfactant or a water-soluble resin as the pigment 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. Furthermore, it is preferably in the range of 3,000 to 15,000. Specifically, styrene, styrene derivatives,
Vinyl naphthalene, vinyl naphthalene derivative, α, β-
Aliphatic alcohol esters of ethylenically unsaturated carboxylic acids, such as acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, fumaric acid derivatives; Block copolymers, graft copolymers, random copolymers, and salts thereof.

These resins are alkali-soluble resins which 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.
It is also possible to use water-soluble resins such as polyvinyl alcohol, carboxymethyl cellulose, and naphthalenesulfonic acid formaldehyde condensate. However, when an alkali-soluble resin is used, there are advantages that the viscosity of the ink can be reduced and the ink can be easily dispersed. Further, a water-soluble resin which starts aggregation at a pH of 6 or less is particularly preferable for improving the printing density. Incidentally, the water-soluble resin,
It is preferably contained in the range of 0.1 to 5% by weight based on the total amount of the ink. The water-soluble resin described above has a low viscosity in a pigment ink in a state close to dispersion, and can be ejected by inkjet.

A tackifying resin may be added to the ink of the present invention, for example, 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-based tackifying resin such as rosin-modified phenol resin, terpene resin, hydrogenated terpene resin, phenol resin, terpene phenol resin, hydrogenated terpene phenol resin, xylene resin, aliphatic petroleum resin And a ring-type petroleum resin, an aromatic petroleum resin, a cumarone resin, and a styrene resin.

Further, the ink of the present invention is preferably such that the whole ink is adjusted to be neutral or alkaline.
It is desirable because the solubility of the water-soluble resin can be improved and the ink can be further excellent in long-term storage. However, in this case, it may cause corrosion of various members used in the ink jet recording and displaying apparatus, so that the pH is preferably in the range of 7 to 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 are mentioned. As described above, the pigment, colloidal silica, emulsion, water-soluble resin and the like are dispersed or dissolved in the aqueous liquid medium of the ink.

The main components constituting the ink used in the present invention are as described above. In addition, urea, a water-soluble organic solvent other than the above, a surfactant, an antifoaming agent, a preservative, etc. may be used as required. May be. Usable water-soluble organic solvents include amides such as dimethylformamide and dimethylacetamide; ketones and ketoalcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; N-methyl-2-pyrrolidone; ,
3-dimethyl-2-imidazolidinone and the like.

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 non-ionic 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 35 dyne / cm or more. This is because the fact that the surface tension of the ink shows a value smaller than this value causes an unfavorable situation such as printing distortion (displacement of the landing point of the ink droplet) due to the wetting of the nozzle tip in the ink jet recording system of the present invention. It is because.

The ink of the present invention is a pigment ink. Pigment inks are 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 ink jet inks, 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 the ink to keep the ink moist before ejection and to adjust the surface tension immediately after printing. Do. When the amount of glycol is large, the viscosity increases to cause ejection failure, drying on the recording medium is delayed, which affects the fixability, and the amount of alcohol affects the surface tension. Therefore, in the present invention, at least the above-mentioned range as the pigment concentration related to the image density, the polymer emulsion is 0.001 to 0.1.
% By weight, 0 to 10% by weight of glycols, 0 to 10% by weight of alcohols, and colloidal silica in the above range.

As the glycols, the alkylene group is 2
Alkylene glycols containing up to 6 carbon atoms are preferred, for example, ethylene glycol, propylene glycol, butylene glycol, triethylene glycol,
1,2,6-hexanetriol, thiodiglycol,
Hexylene glycol, diethylene glycol and the like can be mentioned.

The alcohol is preferably an alkyl alcohol having 1 to 4 carbon atoms. Examples of the aliphatic monohydric alcohol include methyl alcohol, ethyl alcohol,
n-propyl alcohol, isopropyl alcohol, n
-Butyl alcohol, sec-butyl alcohol, te
rt-butyl alcohol and the like. Glycol and alcohol are preferably added in the above range.

The pigment concentration is set within the above range according to the spectral reflection density, color balance, print density, etc. of one color pigment among yellow, magenta, cyan and black. As carbon black used for black ink,
A carbon black produced by a furnace method or a channel method, having a primary particle diameter of 15 to 40 nm (mμ) and a specific surface area of 50 to 300 m ² / g (square m /
g), having a DBP oil absorption of 40 to 150 ml / 100 g, a volatile content of 0.5 to 10% by weight, and a pH value of 2 to 9; 2300, no. 900, MCF88, N
o. 33, no. 40, no. 45, no. 52, MA
7, MA8, No. 2200B (Mitsubishi Chemical), RA
VEN1255 (manufactured by Columbia), REGAL400R. REGAL
330R, REGAL660R, MOGUL L (Cabot),
COLOR Black FW 1, COLOR BlackFW 18, Color Black S
Commercial products such as 170, Color Black S 150, Prlntex 35, and Printex U (Degussa) can be used. Further, a product newly produced for the present invention may be used.

Pigments used in the yellow ink include CI Pigment Yellow 1, CI Pigment Yellow 2, C.I.
I. Pigment Yellow 3, CI Pigment Yellow 13, CI Pig
ment Yellow 16, CI Pigment Yellow 83, pigments used as magenta inks are CI Pigment Red
5, CI Pigment Red 7, CI Pigment Red 12, CI Pigm
ent Red 48 (Ca), CI Pigment Red 48 (Mn), CI Pigmen
t Red 57 (Ca), CI Pigment Red 112, CI Pigment Red
122.As pigments used as cyan ink, C.I.
I. Pigment Blue 1, CI Pigment Blue 2, CI Pigment
Blue 3, CI Pigment Blue 15: 3, CI Pigment Blue 1
6, CI Pigment Blue 22, CIVat Blue 4, CIVat Bl
ue 6 and the like, but those newly manufactured for the present invention can also be used.

Each of the above color pigments other than black is an organic substance, and is often dyed on a recording medium by adsorption or reaction as described above. In the present invention, the above-mentioned colloidal silica is used as a release agent to prevent this. Is added.

One example of a method for producing the ink of the present invention is as follows. The water-soluble resin and distilled water are heated to 70 ° C. to completely dissolve the resin component. 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 dispersing process, any dispersing machine can be used as long as it is a commonly used dispersing machine.
For example, ball mills and roll mills using ceramic balls or steel balls, sand mills using glass beads or ceramic beads, and the like can be given. Among these, a high-speed sand mill is preferable, for example, a super mill,
Sand grinders, bead mills, agitator mills, Glen mills, Dyno mills, pearl mills, Kobol mills (all trade names) and the like. As beads used in the sand mill, glass beads, ceramic beads, zirconium beads and the like having a diameter of 1 mm to 1.5 mm are used. As an example of conditions for preparing a dispersion for ink used in the present invention, the following examples are preferable conditions.

-Dispersing machine: sand grinder (Igarashi Kikai)-Grinding media: 1 mm diameter glass beads or zirconium beads-Filling rate of grinding media: 50% (volume)-Grinding time: 3 to 4 hours

Further, after the dispersion of the pigment, centrifugation (1
(2,000 RPM, 15 to 20 minutes) to remove coarse pigment particles to obtain a pigment dispersion having a particle size of 100 nm to 200 nm. In addition, a pearl mill (manufactured by Ashizawa, discharge speed: 100 ml / min) may be used as the disperser.

It is desirable that the total amount of the pigment and the water-soluble resin in the dispersion is 5 to 30% by weight or more, preferably 10 to 30% by weight 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. As a method of obtaining a pigment having a desired particle size distribution, to reduce the size of the grinding media of the dispersing machine, increase the filling rate of the grinding media, also increase the processing time, slow the discharge speed,
After the pulverization, a method such as classification using a filter or a centrifuge is used. Alternatively, a combination of these methods may be used.

In addition to the above-described ink production method, a 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 and stirred with the pigment dispersion and polymerized to obtain a pigment ink. Similarly,
Colloidal silica may be mixed simultaneously with the pigment dispersion and the polymer emulsion.

Next, the image recording and displaying apparatus of the present invention will be described. The image recording and displaying apparatus of the present invention is characterized by having an image forming unit using the above-described ink,
In a preferred embodiment, there is provided an image recording and displaying apparatus having an ink jet recording means and having an erasing means,
The ink used in the inkjet recording means is the ink of the present invention. Such an image recording and displaying apparatus according to the present invention is an apparatus which not only provides a high-quality color image display compatible with a network, but also addresses resource saving and environmental problems.

FIGS. 1 and 2 show an example of the configuration of a full-color image recording / display apparatus (electronic blackboard) using the ink of the present invention. The full-color electronic blackboard according to the present invention includes at least a belt-shaped recording medium, a recording medium scanning unit, an inkjet head, an inkjet head scanning unit, an ink cartridge, and an ink supply unit. The example shown in FIG. 1 is an example of an image recording and displaying apparatus in the form of a vertical electronic blackboard, and the example shown in FIG. 2 is an image recording and displaying apparatus in the form of a horizontal electronic blackboard.

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 film or sheet such as polyethylene terephthalate. Examples thereof include those which have been coated, those having an acrylic hard coat, a fluorine coat, a silicone coat, etc. on the front surface, and those having various target layers laminated on the back surface.

The endless belt-shaped recording medium is tensioned by at least two rollers,
The recording medium is scanned in a fixed direction by rotating the roller. In order to form an endless belt, seamless processing is usually required and the cost is high. There is also a method in which a winding mechanism is provided at both ends. A tension is applied to the recording medium with two rollers, and the roller is rotated. Scanning the recording medium while winding the belt. In this case, when the belt is wound up, the roller is reversed and returned 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-described 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. An example of a recording and display device suitable for use in the present invention is a device that applies thermal energy corresponding to a recording signal to ink in a chamber of a recording head and generates droplets using the energy.

FIG. 3 shows an example of the configuration of the head, which is the main part. The head 13 includes a glass, ceramics, plastic plate or the like 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. FIG. 3A is a sectional view of the head 13 along the ink flow path, and FIG.
It is a tangent section in the -B line.

The heating head 15 includes a protective film 16 made of silicon oxide or the like, and aluminum electrodes 17-1 and 17-1.
-2, a heating resistor layer 18 made of nichrome or the like, a heat storage layer 19, and a substrate 20 having good heat dissipation properties such as alumina. The ink 21 reaches a discharge orifice (fine hole) 22 and forms a meniscus 23 by the pressure P. Now, when an electric signal is applied to the electrodes 17-1 and 17-2, the area indicated by n of the heating head 15 generates heat rapidly, and bubbles are generated in the ink 21 in contact with the area, and the meniscus is generated by the pressure. 23 protrudes, the ink 21 is ejected, and becomes a recording droplet 24 from the orifice 22.
Fly towards 5.

FIG. 4 is an external view of a multi-head in which a number of heads shown in FIG. 3 are arranged. The multi-head 1 is made by bonding a glass plate 27 having a multi-groove 26 and a heating head 28.

FIG. 5 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 display device used in the present invention is not limited to the above-described head and the ink cartridge which are separated from each other, but also preferably the one in which they are integrated as shown in FIG.

In FIG. 6, reference numeral 70 denotes an ink jet cartridge, which contains an ink absorber impregnated with ink, and in which the ink in the ink absorber passes from a head 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. The ink jet cartridge 70 is used in place of the recording head, and is detachable from the carriage.

The image recording and displaying apparatus of the present invention is preferably a full-color electronic blackboard. In this case, an image is formed using four types of color inks of yellow, magenta, cyan and black. . Each color ink is supplied from a separate ink cartridge to a recording head corresponding to each color as shown in FIG.

[0069]

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the following description, “parts” and “%” are based on weight unless otherwise specified.

Example 1 [Preparation of Color Ink for Electronic Blackboard] Black ink (Preparation of pigment dispersion) ・ Styrene-acrylic acid-butyl acrylate copolymer (acid value 116, weight average molecular weight 3,700) 1.5 parts ・ Monoethanolamine 1 part ・ Ion exchange water 81.5 Parts ・ Diethylene glycol 5 parts

The above components were mixed and mixed in a water bath at 70
Heat to ° C. to completely dissolve the resin. To this solution, 10 parts of newly produced carbon black (MCF88 manufactured by Mitsubishi Kasei) and 1 part of isopropyl alcohol were added, and 3 parts were added.
After premixing for 0 minutes, dispersion treatment was performed under the following conditions. -Disperser: sand grinder (Igarashi Kikai)-Grinding media: zirconium beads 1mm diameter-Filling rate of grinding media: 50% (volume)-Grinding time: 3 hours Further centrifugation treatment (12,000 RPM, 20 minutes) Then, coarse particles were removed to obtain a dispersion.

(Preparation of ink) 10 parts of the above dispersion liquid 0.1 parts of Teisan Resin 370N 0.1 part of colloidal silica (Snowtex OL, manufactured by Nissan Chemical) 10 parts of diethylene glycol 15 parts of N-methylpyrrolidone 5 parts of isopropyl alcohol 3 parts ・ Ion exchange water 57 parts

The above components were mixed, the pH was adjusted to 8 to 10 with monoethanolamine, and the surface tension was adjusted using the following formula as a surfactant to obtain a black ink.

[0074]

Embedded image

2. Yellow ink In the above formula, the pigment carbon black is
A yellow ink was prepared in the same manner as in the preparation of the black ink, except that t Yellow was 13 and colloidal silica was changed to 15 parts. 3. Magenta ink A magenta ink was prepared in the same manner as in the preparation of the black ink, except that the pigment black was changed to CI Pigment Red 7 in the above black ink formulation.

4. Cyan Ink A cyan ink was prepared in the same manner as in the preparation of the black ink, except that the pigment black was changed to CI Pigment Blue 22 in the above black ink formulation.

Using these inks, printing was performed with a recording and display device as shown in FIG. The specific method is as described above. As a result, only the yellow ink had poor wiping properties, and the printed portion was observed by FE-SEM.
The FE-SEM image similar to that shown in FIG. Colloidal silica has a particle size of about 80 to 100 nm, whereas many of the pigment particles are irregular and have a size of 40 to 10 nm.
0 nm, and it was found that it was present in a network on the recording medium.

According to this morphological observation, the pigment of the yellow ink was much smaller than the diameter of the colloidal silica particles added to the ink. Therefore, when printed, the pigment slipped through the colloidal silica particles and fell to the lower layer. It seems that it has taken root. Therefore, the above-mentioned yellow ink having a particle size of 80 nm or less was not used due to the filtering operation. Here, by using the pigment of the yellow ink having approximately the same size as the particles of the colloidal silica, the wiping property became very good.

Example 2 As in Example 1, printing was performed by the image recording and displaying apparatus shown in FIG. As a result, the wiping properties of the yellow ink were also not excellent, so that the particle diameter of the added colloidal silica was reduced. Therefore, only yellow ink,
It was decided to use a small colloidal silica. In Example 1, the size of the yellow pigment particles was about 50 to 80.
Therefore, the colloidal silica of the present example is 5 nm.
An ink having a particle diameter of about 0 nm was prepared. Thus, the wiping properties were greatly improved.

[0080]

The image recording and displaying apparatus using the ink provided by the present invention not only provides a high-quality color image display compatible with a network, but also provides an apparatus which saves resources and copes with environmental problems. . By using the ink jet recording means using the above-described ink, the dyeing which was a problem in the conventional recording method can be solved, and high-quality printing and erasing can be repeatedly performed on the recording medium.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an example of a recording and display device according to the present invention.

FIG. 2 is a diagram illustrating a configuration of another example of the recording and display device of the present invention.

FIG. 3 is a cross-sectional view illustrating a configuration example of a head that ejects ink by thermal energy.

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

FIG. 5 is a cross-sectional view illustrating an example of an ink cartridge.

FIG. 6 is a perspective view illustrating a recording and display device in which a head and an ink cartridge are integrated.

FIG. 7 is a configuration diagram in which a multi-head is connected to ink cartridges of four colors.

FIG. 8 is a field emission scanning electron microscope image illustrating the state of colloidal silica and pigment particles on a recording medium using the ink having good wiping properties of the present invention.

FIG. 9 is a field emission scanning electron microscope image illustrating the state of colloidal silica and pigment particles on a recording medium using ink with poor wiping properties.

[Explanation of symbols]

 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 Small droplet 25: Recording medium 26: Multi-groove 27: Glass plate 28: Heating head 111, 112, 115: Pigment 113, 114, 116: Colloidal silica 121, 123, 125: Pigment 122, 124, 126: Colloidal silica

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshinori Tomita 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Yasuko Motoi 3-30-2 Shimomaruko, Ota-ku, Tokyo Non-corp. F term (reference) 2C056 FC01 2H086 BA11 BA55 BA59 BA60 BA62 4J039 AB02 AD02 AD03 AD06 AD08 AD09 AD10 AD13 AD14 AD17 AE01 BA04 BA14 BA21 BA29 BC19 BC35 BE01 BE22 BE30 CA06 EA15 EA16 EA17 EA19 EA29 GA24

Claims (9)

[Claims] 1. An ink jet ink containing a pigment and colloidal silica, wherein the size of the pigment particles is the same as or larger than the size of the colloidal silica particles. 2. The colloidal silica having an average particle size of 20 to 20.
2. The ink according to claim 1, which is in the range of 100 nm. 3. The pigment particles having an average particle size of 20 to 100.
2. The ink of claim 1 in the range of nm. 4. The method according to claim 1, wherein the content of the pigment is 2% by weight to 1% by weight of the ink.
The ink according to claim 1, wherein the content of colloidal silica is 0% by weight, the content of colloidal silica is 2% by weight to 20% by weight of the ink, and the content of colloidal silica is larger than the content of the pigment. 5. The ink according to claim 1, further comprising a polymer emulsion. 6. The ink according to claim 5, wherein the glass transition temperature of the polymer emulsion is 0 ° C. or lower. 7. The ink according to claim 1, further comprising a pigment dispersant which starts aggregation at a pH of 6 or less. 8. An image recording and displaying apparatus comprising an image forming unit using the ink according to claim 1. Description: 9. An image recording and displaying apparatus having an ink jet recording means and having an erasing means, wherein the ink used in the ink jet recording means is an ink jet recording means.
An image recording and display device, which is the ink according to any one of the above.