JPH0732720A - Ink jet recording method - Google Patents

Abstract

PURPOSE:To provide an ink jet recording method capable of obtaining a recording image having high density and high resolving power and excellent in transparency and surface glossiness. CONSTITUTION:In an ink jet recording method using cyan, magenta, yellow and black inks, inks set to 25-35dyne/cm in surface tension and a recording medium wherein a coating layer with a saponification value of 75-98mol% and a polymerization degree of 100-500 or a derivative thereof is provided on a base material are used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording method capable of providing an image having a high density and a high resolution, and particularly suitable for providing a recorded image excellent in translucency or surface gloss. The present invention relates to an inkjet recording method.

[0002]

2. Description of the Related Art Conventional ink jet recording methods have been used.
As a recording medium for forming an image, Japanese Patent Publication No.
As described in Japanese Patent Publication No. 5, a finely divided silica and a water-soluble binder such as polyvinyl alcohol are formed on a base paper, and a finely divided silica and a water-soluble binder such as polyvinyl alcohol are formed on the base paper. A recording paper provided with a coating layer containing the same, or a saponification degree of 50 to 90 on cast coated paper as described in JP-B-3-25352.
Glossy paper having a film containing mol% of polyvinyl alcohol and a cross-linking agent, and further, JP-A-60-220750.
As described in Japanese Patent Laid-Open Publication No. JP-A No. 2004-187, recording sheets for overhead projectors (OHP) have been used in which a hydrophilic film made of water-soluble polyvinyl alcohol having a saponification degree of 70 to 90 mol% is provided on a polyester film.

[0003]

In recent years, speeding up of recording,
Along with the improvement in the performance of inkjet recording apparatuses such as multicolor printing, more advanced and broader characteristics are required for inkjet recording media. That is, (1) the ink absorption capacity is high (the absorption capacity is large, the absorption time is fast), (2) the optical density of the dot is high, and the periphery of the dot is not blurred. (3) The dot shape is close to a perfect circle. It is required that the surroundings be smooth (4) The characteristics should not change due to changes in temperature and humidity, and that curling should not occur (5) Blocking should not occur. (6) The image is stable and does not deteriorate for long-term storage (especially,
(7) Under high temperature and high humidity environment (7) Preservability such as that the recording medium itself is stable and does not deteriorate during long-term storage (especially under high temperature and high humidity environment) is also required.

Further, by using the ink jet recording method,
There is also a demand for forming an image with excellent transparency that can be used for OHP and an image having high gloss on the surface,
There is also a need for a recording sheet having excellent translucency and a recording sheet having a surface gloss (glossy paper). These recording sheets, in order to suppress the diffuse reflection of incident light on the recording surface,
Since it is necessary to provide a transparent coating layer as much as possible, it has been formed by providing an ink receiving layer mainly containing a hydrophilic resin such as polyvinyl alcohol as described in the section of the prior art.

Particularly, in a recording method for forming a translucent image or a surface glossy image, the recording speed is increased,
As the density of images becomes higher and the colors become higher, deterioration of image quality due to defective ink fixing on the recording sheet becomes a serious problem. That is, since the recording surface of these recording sheets does not have a porous structure like conventional coated paper or plain paper,
Since the ink absorption capacity is insufficient, image stains due to ink overflow in areas with high image density, that is, areas with large ink hits, and uneven density (beads) such as unfixed ink droplets on the recording surface In particular, in the case of color printing, color smear (boundary bleeding) is caused by color mixture at the boundary portion of different colors. These phenomena significantly reduce the sharpness of the image.

The recording sheet provided with the ink receiving layer mainly composed of polyvinylpyrrolidone described in JP-B-3-29596 has a relatively good ink absorbing capacity at room temperature and normal humidity, but under high temperature and high humidity. However, the ink has a drawback that the drying of the ink is extremely slow and blocking is likely to occur, and the mechanical strength of the recording surface is weak and is easily scratched.

In particular, in the recording method using the recording sheet having the above-mentioned translucency or surface glossiness, an attempt is made to improve the conventional recording sheet with respect to the problem of beading or boundary blurring which is a remarkable problem. However, a sufficiently effective recording sheet has not been obtained, and almost no studies have been made to solve these problems from the aspects of ink and recording sheet.

Therefore, an object of the present invention is to provide an ink jet recording method which simultaneously satisfies the above required characteristics in a well-balanced manner. In particular, it has high density, high resolution, and excellent transparency or surface gloss. Another object of the present invention is to provide an inkjet recording method capable of providing a recorded image.

[0009]

The above object can be achieved by the present invention described below.

That is, the present invention provides an ink jet recording method for performing color recording by ejecting small droplets of cyan, magenta, yellow and black ink from an orifice of a recording head in accordance with a recording signal and adhering them to a recording medium. Has a surface tension of 25 to 35 dy
Polyvinyl alcohol having a saponification degree of 75 to 98 mol% and a polymerization degree of 100 to 500, which is in the range of ne / cm, and on which the recording medium is provided on the base material and the base material. The inkjet recording method is characterized by including a coating layer formed mainly of a derivative.

In the present invention, the coating layer of the recording medium contains polyalkylene oxide or a derivative thereof, and the coating layer contains a vinyl monomer having a cationic group and a vinyl monomer having a hydrophobic group. Containing a hydrophilic acrylic resin which is a copolymer of 0.
Including an epoxy compound in an amount of 5% or more, and an inkjet recording method in which the base material of the recording medium is a plastic film.

The liquid medium component of the ink is an ink jet recording method mainly composed of water and a water-miscible glycol or glycol ether, and at least an orifice for ejecting ink of each color is provided. An inkjet recording method in which two or more ink droplets of the same color are ejected at the same time, and recording is performed by ejecting two or more ink droplets of the same color at the same time. That is, it includes an inkjet recording method in which at least the maximum recording density of each color ink is 6 nl / mm ² or more, and an inkjet recording method in which ink is ejected by ink thermal energy.

[0013]

The present inventors have found a method of forming a transparent image that can be used in, for example, an overhead projector or the like, or an image having a high gloss surface comparable to a silver salt photograph, by using an inkjet recording method. In the examination,
By performing ink jet recording on a recording medium coated with the composition using an ink having a surface tension in the specific range, an image satisfying the required performance can be formed, and particularly, The inventors have found that it is possible to form a high-quality recorded image without the occurrence of beading or boundary bleeding, which was a significant problem in forming a recorded image as described above, and completed the present invention. Is.

According to the findings of the present inventors, the problem of beading and boundary bleeding is not only the problem due to insufficient ink absorbability of the recording medium as described above, but also the problem of adhesion to the recording sheet. It is also a problem related to the wettability between the ink and the surface of the recording sheet. That is, if the wettability of the ink to the surface of the recording sheet is insufficient in the area where solid printing, or recording close to it, is caused, a slight misalignment of the position where the ink droplets land on the surface of the recording sheet, Unfixed ink droplets of adjacent pixels on the surface of the sheet gather together in an irregularly connected form in units of several to several tens, and become an isolated state. Seeming beading phenomenon occurs. On the other hand, when the wettability is good, almost all unfixed ink droplets are uniformly connected to form an aggregated state.
The recording area appears uniform without uneven density. On the other hand, if the wettability is too good, this occurs at the boundary portions recorded with different color inks, resulting in color mixing, which causes blurring of the boundary. As described above, it has been found that these problems are problems in which it is difficult to obtain a sufficient solution even if the improvement is made only on the recording medium side.

Adjusting the surface tension of the ink so as to optimize the wettability of the ink on the recording sheet is one means for solving the above problems. However, according to the examination results of the present inventors, not only the preferable range of the surface tension of the above ink is different depending on the material constituting the recording sheet surface, but the preferable range is extremely narrow,
It has been found that there is no range in which both are compatible, and the image quality level when optimized is also different. From the results of such studies, the present inventors selected a specific material as a recording medium forming material in consideration of the synergistic effect of the combination with ink, and further selected the most suitable surface tension for the material. The present inventors have found that it is possible to form a high-quality light-transmitting image and surface gloss image that could not be obtained by combining the inks with the present invention, and arrived at the present invention.

The translucent recording sheet referred to in the present invention has a linear transmittance of 30% or more. The linear transmittance (T%) means that the light is incident on the sample perpendicularly, is transmitted through the sample, is transmitted through the light receiving slit on the extension line of the incident light path at a distance of at least 8 cm from the sample, and is received by the detector. The spectral transmittance of linear light is measured by using, for example, a 323 type Hitachi self-recording spectrophotometer (manufactured by Hitachi, Ltd.) or the like, and the Y value of the color tristimulus values is obtained from the measured spectral transmittance. This is the value obtained from the formula.

T = (Y / Y0) × 100 T; linear transmittance Y; Y value of sample Y0; Y value of blank

The surface glossy recording sheet referred to in the present invention is a sheet having a 60-degree specular gloss of 30% or more on at least one surface. What is 60 degree specular gloss? JIS-Z-8
It is a value measured based on 741.

Next, the present invention will be described in more detail with reference to preferred embodiments.

The first feature of the present invention is to use a recording medium having a coating layer containing a specific material, that is, a specific polyvinyl alcohol. The above polyvinyl alcohol can be obtained by saponifying a vinyl acetate homopolymer with an acid or an alkali to a predetermined degree of saponification. As a derivative of polyvinyl alcohol, a modified product obtained by saponifying a copolymer of vinyl acetate and, for example, vinyl chloride, ethylene, maleic acid, itaconic acid, acrylic acid, dimethylaminoethyl methacrylate, or a quaternary product thereof. Polyvinyl alcohol,
A compound having reactivity with a hydroxyl group in a polyvinyl alcohol molecule, for example, a melamine resin, an isocyanate compound,
Examples thereof include reaction products of polyvinyl alcohol with aldehydes, epoxy compounds, compounds containing boron or chromium, and the like, such as polyvinyl acetal and polyvinyl formal.

The preferred saponification degree of the polyvinyl alcohol is in the range of 75 to 98%, more preferably 85 to 90%. When a recording medium using a recording medium outside this range is used in the present invention, the ink absorbing ability is low and the image quality such as beading and boundary blurring is poor.

The optimum range of the degree of polymerization is 100 to 500.
Within the range of. In this respect, the higher the degree of polymerization is, the better the ink absorption capacity is, which is different from the prior art which is considered preferable. When an ink having a low surface tension that is preferable for polyvinyl alcohol is used, the use of polyvinyl alcohol having a polymerization degree of more than 500 gives better image quality such as beading and boundary blurring than using polyvinyl alcohol in the above range. .

The recording medium used in the present invention is a recording medium having a coating layer (ink receiving layer) on the surface of a substrate by coating the composition containing polyvinyl alcohol on at least one surface of the substrate. However, various binders and filler additives can be used in combination in this composition within a range that does not prevent the achievement of the object of the present invention. Examples of the binder include conventionally known starch, cationized starch, casein, gelatin, acrylic resin, maleic anhydride resin, melamine resin, urea resin, SBR latex, sodium alginate, polyvinylpyrrolidone, carboxymethylcellulose, and hydroxyethylcellulose. Are not limited to these. Examples of the filler include silica, alumina, aluminum silicate,
Inorganic pigments such as magnesium silicate, basic magnesium carbonate, takule, clay, hadodaltalcite, calcium carbonate, titanium oxide, zinc oxide, and polyethylene,
Examples thereof include plastic pigments such as polystyrene and polyacrylate, but are not limited thereto. Specific examples of the additives include various surfactants, dye fixing agents (waterproofing agents), defoaming agents, antioxidants, optical brighteners, ultraviolet absorbers, dispersants, viscosity adjusting agents, pH adjusting agents. , Antifungal agents, plasticizers and the like. These additives may be arbitrarily selected from conventionally known compounds according to the purpose.

The recording medium used in the present invention is more effective when the coating layer further contains the following materials.

As one of the preferable materials, polyalkylene oxide or its derivative can be mentioned. Polyalkylene oxide is a polyhydroxy compound obtained by adding ethylene oxide and / or propylene oxide to a compound having two or more active hydrogen groups. Examples of the compound having two or more active hydrogen groups include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,4 butanediol, 1,6 hexanediol, tetraethylene glycol, polyethylene glycol, polypropylene glycol, Examples include propylamine, butylamine, octylamine, cyclohexylamine, bisphenol A, glycerin, trimethylolpropane, pentaerythritol, monoethanolamine, diethanolamine, triethanolamine, isopropanolamine and the like. Examples of the polyalkylene oxide derivative include reaction products of the above polyhydroxy compounds and compounds having reactivity with these. It is desirable that these have a weight average molecular weight of at least 20,000 or more. Those having a low molecular weight have strong adhesiveness even after the ink receiving layer is formed, and are likely to cause blocking and the like.

Particularly preferable polyalkylene oxide compounds include the following. That is, it is a polymer having a weight average molecular weight of 20,000 or more obtained by reacting the polyhydroxy compound having a weight average molecular weight of 1,000 or more with a polyvalent carboxylic acid, an acid anhydride thereof, or a lower alkyl ester thereof. Specific examples of the polycarboxylic acid to be reacted with the polyhydroxy compound include malonic acid, maleic acid, succinic acid, fumaric acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, adipic acid, sebacic acid, dimer acid and pyrol. Examples thereof include meritic acid and trimellitic acid. Examples of the lower alkyl ester include monomethyl, dimethyl, monoethyl, diethyl, monopropyl, dipropyl, monobutyl, dibutyl ester and the like. The reaction of such a polyhydroxy compound with a polycarboxylic acid, an acid anhydride thereof, or a lower alkyl ester thereof is dehydrated or dealcoholized (transesterification) under reduced pressure of 0.001 to 20 mmHg under heating at 80 to 250 ° C. It is obtained by carrying out the reaction for 30 minutes to 10 hours. When the molecular weight of the polymer compound obtained here is less than 20,000, the film strength is weak and the blocking resistance is unsatisfactory. Next, this polymer will be described more specifically with reference to synthetic examples, but the present invention is not limited to these synthetic examples.

Synthesis Example 1 140 parts of glycerin and 2 parts of caustic potash in an autoclave
0 parts were charged and ethylene oxide 1 was added under heating at 130 ° C.
The reaction was carried out while gradually adding 2000 parts. When the weight average molecular weight of the reaction product (intermediate) was calculated by measuring the hydroxyl value and the alkali value, it was about 8000. Next, 100 parts of this product was taken, 2 parts of dimethyl terephthalate was added, the temperature was raised to 125 ° C., and then methanol was removed under reduced pressure of 1 mmHg. The weight average molecular weight of the obtained polymer was about 150,000 as measured by high performance liquid chromatography.

Another preferable material for the recording medium used in the present invention is a hydrophilic acrylic resin which is a copolymer of a vinyl monomer having a cationic group and a vinyl monomer having a hydrophobic group. You can This hydrophilic acrylic resin is formed of at least one monomer selected from at least the following two groups.
Examples of the monomer having a cationic group include dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate,
Diethylaminoethyl methacrylate, methylethylaminoethyl acrylate, methylethylaminoethyl acrylate, dimethylaminostyrene, diethylaminostyrene, methylethylaminostyrene, and quaternized compounds thereof, etc., with a primary to tertiary amine to quaternary ammonium base in the side chain. Can be mentioned. Examples of the monomer having a hydrophobic group include alkyl acrylate such as methyl acrylate and ethyl acrylate, alkyl methacrylate such as methyl methacrylate and ethyl methacrylate, styrene, vinyltoluene, vinyl acetate and ethylene. Can be mentioned. The copolymerization ratio of these is preferably in the range of 1/9 to 9/1. Also,
Other hydrophilic monomers such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate,
It may be included if necessary.

Further, in the present invention, the mechanical strength of the recording surface can be further improved by containing the epoxy compound in the coating layer in a proportion of 0.5% by weight or more. Specific examples of epoxy compounds include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl alcohol diglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether. , Diglycerol polyglycidyl ether and the like.

As described above, in the recording medium of the present invention, when an ink receiving layer containing the above-mentioned material in addition to the above-mentioned polyvinyl alcohol is provided on at least one surface of the substrate, all the above-mentioned requirements are met. It is preferable since the characteristics can be satisfied in a well-balanced manner, and further, the deterioration of the recording medium itself and the image of the recording medium itself when the image is left in a high temperature and high humidity environment for a long time can be suppressed as much as possible.

The polyethylene oxide or its derivative in the above-mentioned preferred embodiment is added to the ink receiving layer in an amount of 2 to 2.
It is preferably contained in a proportion of 10% by weight. If the amount is less than the above range, the quality of the recording medium itself deteriorates (decrease in ink absorbability), especially when left in a high temperature and high humidity environment for a long time.
Is likely to occur. When the amount is more than the above range, even if a hydrophilic acrylic resin that is a copolymer of a vinyl monomer having a cationic group and a vinyl monomer having a hydrophobic group is used together, it is left for a long time in a high temperature and high humidity environment. In that case, alteration (dots bleed over time and the sharpness of the image decreases) is likely to occur. Conventionally, it was known that when polyvinyl alcohol and polyalkylene oxide were poorly compatible with each other and formed into a coating film, they were separated with time and became cloudy. By using together with a hydrophilic acrylic resin, which is a copolymer of a monomer and a vinyl-based monomer having a hydrophobic group, it is possible to prepare a recording medium with excellent transparency that can be sufficiently used as a recording sheet for OHP. Become. In this respect, the content of the hydrophilic acrylic resin, which is a copolymer of the vinyl monomer having a cationic group and the vinyl monomer having a hydrophobic group, in the ink receiving layer is at least larger than that of polyalkylene oxide or its derivative. Is desirable. In the above aspect,
The hydrophilic acrylic resin, which is a copolymer of a vinyl monomer having a cationic group and a vinyl monomer having a hydrophobic group, is preferably contained in the ink receiving layer in a proportion of 10 to 40% by weight. When the amount is less than the above range, even if the polyalkylene oxide or the derivative thereof is contained in the above range, bleeding of the image with time in a high temperature and high humidity environment is likely to occur. When it exceeds the above range, unevenness occurs on the image, which is not preferable.

The base material constituting the recording medium used in the present invention includes high-quality paper, medium-quality paper, art paper, bond paper, recycled paper, baryta paper, cast coated paper, cardboard paper and the like, and polyethylene terephthalate. , Film or plate made of plastic such as diacetate, triacetate, cellophane, celluloid, polycarbonate, polyimide, polyvinyl chloride, polyvinylidene chloride, polyacrylate, polyethylene, polypropylene, cotton plate, cotton, rayon, acrylic, nylon, silk, Cloth such as polyester can be used. It is appropriately selected from the above-mentioned base materials depending on the recording purpose of the recording medium, the use of the recorded image, or various conditions such as adhesion to the composition coated on the upper side thereof. When adjusting the transparent recording sheet or surface glossy recording sheet,
Plastic film is good.

In preparing the recording medium used in the present invention, first, the composition for forming a coating layer is dissolved or dispersed in water or alcohol, or other appropriate organic solvent together with other additives, if necessary. And adjust the coating liquid.

The obtained coating liquid is applied, for example, to a roll coater method, a blade coater method, an air knife coater method, a gate roll coater method, a bar coater method, a size press method, a spray coat method, a gravure coater method, a curtain coater method, etc. To coat the surface of the substrate. Then, the recording medium of the present invention is obtained by drying using, for example, a hot air drying oven, a heating drum or the like. Further, super calendar treatment or the like may be applied if necessary.

The total coating amount of the ink receiving layer is 0.2 to 50 g / m ² , more preferably 1 to 30 g / m 2.
It is within the range of ² . When the coating amount is small, a part of the base material may be exposed on the surface. Also, the coating amount is 0.2g
/ M ² is less effective in terms of color development of the paint than the case where no ink receiving layer is provided, while
When the amount is more than 50 g / m ² , curling particularly under low temperature and low humidity environment is extremely unfavorable. When the coating amount is expressed by the thickness, the coating amount is preferably in the range of 0.5 to 100 μm.

The second feature of the ink jet recording method of the present invention is that recording is performed on the recording medium described above using an ink having a surface tension of 25 to 35 dyne / cm, more preferably 25 to 33 dyne / cm. There is something to do. When an ink having a surface tension of more than 35 dyne / cm is used, beading is remarkable even when the recording medium of the present invention is used, which is not preferable. Also, 25 dyn
If it is not more than e / cm, an image without beading can be obtained, but the boundary blurring becomes worse. The surface tension referred to in the present invention is a value measured at 25 ° C.

The ink used in the present invention comprises a dye for forming an image and a liquid medium for dissolving or dispersing the dye as essential components, and if necessary, various dispersants, surfactants, and viscosity adjusting agents. It is adjusted by adding an agent, a specific resistance adjusting agent, a pH adjusting agent, an antifungal agent, a recording material dissolution (or dispersion) stabilizer, and the like.

Examples of the recording agent used in the ink include direct dyes, acid dyes, basic dyes, reactive dyes, food dyes, disperse dyes, oil dyes and various pigments. Can be used without. The content of such a dye is determined depending on the type of liquid medium component, the properties required for the ink, etc., but in general, it is about 0.1 to 20% by weight in the conventional ink. It is used, and the ratio may be the same in the present invention.

In the ink used in the present invention, the liquid solvent that dissolves or disperses the dyes as described above contains water or water and a polyhydric alcohol having a water-soluble organic solvent as an ink drying preventing effect. is there.

Organic solvents usable in the ink of the present invention include alkyl alcohols such as methanol, ethanol, isopropyl alcohol and n-butanol; amides such as dimethylformamide and dimethylacetamide;
Acetone, ketones such as acetone alcohol, keto alcohols; ethylene glycol, propylene glycol,
Alkylene glycols such as triethylene glycol, thiodiglycol, diethylene glycol, 1.2.6-hexanetriol, polyethylene glycol; glycerins; (di) ethylene glycol monomethyl (or ethyl) ether, triethylene glycol mono (or di) Alkyl ethers of polyhydric alcohols such as methyl (or ethyl) ether; sulfolane, n-methyl-2-pyrrolidone, 1.3-dimethyl-2-imidazolidinone, and one or more of them are used. .

The ink used in the present invention is adjusted to the above-mentioned predetermined surface tension by using the above materials and further adding a surfactant or the like as necessary.

Examples of the surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene cetyl ether; polyoxyethylene alkyl such as polyoxyethylene nonylphenyl ether and polyoxyethylene octylphenyl ether. Phenyl ethers; sorbitan monooleate, sorbitan trestearate, and other sorbitan fatty acid esters; glyceryl monostearate, glyceryl monooleate, and other glycerin fatty acid esters; polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxy Ethylene fatty acid esters, propylene glycol fatty acid esters, pentaerythritol fatty acid esters, acetylene glycol, acetylene alcohol And nonionic surfactants such as fluorine-based surfactants. In addition to these, alkyl sulfates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl ether phosphates, alkylbenzene sulfonates, Examples thereof include, but are not limited to, anionic surfactants such as alkylsulphosuccinates, and cationic surfactants such as benzaconium chloride and quaternary ammonium salts of cetyltrimethylammonium chloride. Among the above, acetylene glycol and acetylene alcohol are particularly preferable.

As an example of the ink containing the above-mentioned acetylene glycol and acetylene alcohol, there is disclosed in Japanese Patent Laid-Open No.
The ink described in JP-A-3-139964 can be mentioned, but the preferable range of the surface tension of the ink described on the left is 35 to 65 dyne / cm, and the preferable range of the surface tension of the ink of the present invention is Is different from. As described above, in the present invention, recording is performed using a recording sheet having a coating layer mainly composed of polyvinyl alcohol having a low degree of polymerization, which has not been relatively preferable in the past, and an ink having a low surface tension. By doing so, it has become possible to form a high-quality light-transmitting image and surface glossy image that do not cause beading and boundary bleeding, which could not be achieved in conventional studies.

The ink jet recording method of the present invention may be of any type as long as it can effectively separate the ink from the nozzles and apply the ink to the recording medium which is a range, but in particular, JP-A-54 is used. In the method described in Japanese Patent Publication No. 59936, the ink jet method in which the ink subjected to the action of thermal energy causes a rapid volume change, and the ink is ejected from the nozzle by the action force due to this state change, should be effectively used. You can

An example of an inkjet recording apparatus suitable for the inkjet recording method of the present invention will be described below. An example of a head configuration that is a main part of the apparatus is shown in FIGS.
Shown in.

The head 13 is a glass, ceramic or plastic plate having a groove 14 through which ink passes, and a heating head 15 used for heat-sensitive recording (a head is shown in the drawing, but is not limited to this). It is obtained by bonding and. The heating head 15 includes a protective film 16 formed of silicon oxide, aminium electrodes 17-1 and 17-2, a heating resistor layer 18 formed of nichrome, a heat storage layer 19,
It is made of 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 an electric signal 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 meniscus 23 is projected by the pressure, the ink 21 is ejected, becomes a recording droplet 24 from the orifice 22, and is ejected toward the recording sheet 25. FIG. 3 shows an external view of a multi-head in which many heads shown in FIG. 1 are arranged. The multi-head includes a glass plate 27 having multi-grooves 26, and FIG.
The heating head 28 similar to that described in FIG.

Incidentally, FIG. 1 shows the head 13 along the ink flow path.
2 is a cross-sectional view of FIG. 2, and FIG. 2 is a sectional view taken along line AB of FIG.

FIG. 4 shows an example of an ink jet recording apparatus incorporating such a head. In FIG. 4, 61
Is a blade serving as a wiping member, one end of which is held by a blade holding member to be a fixed end, which is in the form of a cantilever. The blade 61 is arranged at a position adjacent to the recording area by the recording head, and in the case of this example, is held in a form protruding in the moving 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,
The recording head is held in a protruding form in the moving path of the recording head.
The blade 61, the cap 62, and the absorber 63 constitute a discharge recovery unit 64, and the blade 61 and the absorber 6
By the means 3, water, dust and the like are removed from the ink ejection port surface.

Reference numeral 65 denotes a recording head having ejection energy generating means, which ejects ink onto a recording medium facing the ejection port surface on which ejection ports are arranged for recording, and 66 denotes the recording head 65 on which the recording head 65 is mounted. It is a carriage for moving. The carriage 66 slidably engages with the guide shaft 67, and a part of the carriage 66 is connected (not shown) to a belt 69 driven by a motor 68. Accordingly, the carriage 66 can move along the guide shaft 67, and the recording area by the recording head 65 and the area adjacent thereto can be moved.

Reference numeral 51 designates a paper feed section for inserting a recording medium, and 5
A paper feed roller 2 is driven by a motor (not shown). With these configurations, the recording medium is fed to the position facing the ejection opening surface of the recording head, and is ejected with the ejection roller 53 arranged as the recording progresses.

In the above structure, when the recording head 65 returns to the home position after recording is completed, the cap 62 of the head recovery section 64 is retracted from the movement path of the recording head 65, but the blade 61 is projected 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 protruding surface of the recording head 65 to perform capping, the cap 62 moves so as to protrude into the moving 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-described 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 the home adjacent to the recording area at a predetermined interval while the recording head moves in the recording area for recording. The wiper is moved to the position, and the wiping is performed along with the move.

As described above, in the present invention, in particular, in forming a translucent recorded image or a recorded image excellent in surface gloss by using the ink jet recording system, high speed recording, high density recording and colorization are realized. Its main purpose is to solve the problems of beading and boundary blurring that accompany the above. Therefore, the present invention is not effective in low-speed or low-density recording because such a problem is not so remarkable. The inkjet recording method of the present invention is a color inkjet recording method in which a droplet of each color ink is ejected from an orifice of a recording head at a drive frequency of at least 3 KHz to perform recording, and at least each color ink is ejected. A recording method using an inkjet recording apparatus having two or more orifices for each color and capable of ejecting two or more ink droplets of the same color at the same time, wherein the maximum recording density of each color ink is 6 nl / mm. ^The inkjet recording method is ² or more.

The maximum recording density referred to in the present invention is obtained by multiplying the maximum number of single-color ink droplets that can be deposited per unit area when the recording system is used by the volume of the ejected ink droplets. It is a thing.

[0058]

The present invention will be described in more detail with reference to the following examples. In the text, “part” or “%” is based on weight unless otherwise specified.

(Preparation of Recording Sheet) A coating solution for forming a coating layer having the following composition was applied to a polyethylene terephthalate film (thickness 100 μm; manufactured by Lumirror Toray) using a wire bar so that the coating thickness after drying was 20 μm. Then, it was dried at 100 ° C. for 10 minutes to prepare recording sheets of the present invention and comparative recording sheets.

Coating Liquid Composition Sheet 1 Polyvinyl alcohol used in the present invention (SMR-10
H Shin-Etsu Chemical Co., Ltd.) 10 parts Water 90 parts Sheet 2 Polyvinyl alcohol used in the present invention (SMR-30
H Shin-Etsu Chemical) 10 parts Water 90 parts Sheet 3 Polyvinyl alcohol used in the present invention (B-03 Denki Kagaku Kogyo) 10 parts Water 90 parts Sheet 4 Polyvinyl alcohol used in the present invention (B-03 Denki Kagaku Kogyo) ) 14 parts Polyethylene oxide (Alcox R-40 manufactured by Meisei Chemical Co., Ltd.) 1 part Hydrophilic acrylic resin (Jurimer SP-50 manufactured by Nippon Pure Chemical Co., Ltd.) which is a copolymer of methyl methacrylate and an acrylic quaternary ammonium salt compound 5 Part Water / isopropyl alcohol mixed solvent
80 parts Sheet 5 Polyvinyl alcohol having a saponification degree of 98 to 99% and a polymerization degree of about 1700 (PVA-117 manufactured by Kuraray) 10 parts Water 90 parts Sheet 6 Cationic polyvinyl alcohol having a saponification degree of 80 to 89% and a polymerization degree of 1800 (PVA-C-318-2A
Kuraray Co., Ltd.) 10 parts Water 90 parts The base film used in the preparation of the above-mentioned recording sheet was used as it was to form a sheet 7.

A sheet 8 was prepared in the same manner as the sheet 1 except that a white polyethylene terephthalate film (made by Melinex ICI) was used as the substrate, and a sheet was prepared in the same manner as the sheet 4 except that the art paper was used as the substrate. 9 was adjusted.

On the above recording sheet, color recording was performed under the following conditions by using the ink composition of the present invention and the comparative composition having the following composition and an ink jet recording apparatus for ejecting the ink by foaming the ink by thermal energy. For the combination of recording sheet and ink used for recording,
It is described in Table 1. Ink composition Dye 4 parts Glycerin 6 parts Thiodiglycol 6 parts Urea 8 parts Acetylene glycol (trade name; Surfynol 104)
Nisshin Chemical Co., Ltd.) x part water 76-x part dye Y: C.I. I. Direct Yellow # 86 M: C.I. I. Acid Red # 23 C: C.I. I. Direct Blue # 199 Bk: C.I. I. Hood Black # 2 Ink A x = 0.3 Surface tension = 46 dyne / cm
Ink B x = 1 Surface tension = 29 dyne / cm Ink C x = 3 Surface tension = 26 dyne / cm Ink D x = 10 Surface tension = 21 dyne / cm Ink E x = 1 Surface tension = 31 dyne / cm Instead of acetylene glycol, Acetylene alcohol (trade name; Surfynol 61 manufactured by Nisshin Chemical Co., Ltd.) is used. Ink F x = 1.5 Surface tension = 33 dyne / cm
Instead of acetylene glycol, polyoxyethylene noniphenyl ether (trade name; Inogen EA-5
0 Daiichi Kagaku) is used. Recording conditions Discharge frequency: 5 KHz Discharged droplet capacity: 50 pl Recording density: 360 DPI Single color maximum recording density: 10 nl / mm ^{2 The} following items were evaluated for the obtained color print samples.

(Evaluation Items) (1) Image Density Solid printing (200% Duty) using the above recording device.
The image density of black (Bk) of the printed matter, when it is a translucent image, Macbeth transmission densitometer TD-904,
In other cases, evaluation was performed using a Macbeth densitometer RD-918.

(2) Image unevenness was evaluated on the following two items.

(I) Beading In a solid print portion of each of red, green, and blue, which is a mixed color of two single-color inks of a solid print on the solid print using the above recording apparatus, uneven density is not recognized. Was marked with ◯, a mark which could be visually confirmed from a distance of 25 cm between the printed matter and the eye was marked with x, and a medium mark was marked with Δ.

(Ii) Bleeding at Boundary In a solid print portion where red, green, and blue, which are a mixture of two single-color inks of a print solid-printed using the above recording apparatus, are adjacent to each other, The one in which the boundary line can be clearly confirmed by visual observation from a distance of 25 cm was marked with ◯, the one in which color mixing occurred and could not be recognized as one line was marked with ×, and the middle one was marked with Δ.

(3) Comprehensive Evaluation In the case of a translucent recording image, it is a projected image when projected by an overhead projector (model number: CL-303 Lion), and the surface gloss recording image is visually observed. Was evaluated comprehensively.

∘ when the boundary is clear and there is no uneven density in the printed area and a high-density projected image can be obtained. When the color mixture occurs at the boundary and uneven density occurs in the printed area, the ink flow is out. Occurrences that cannot be read in the projected image XX,
The middle of ○ and × was set as △.

The evaluation results are summarized in Table 1.

[0070]

[Table 1]

[0071]

As described above, according to the present invention, a translucent recorded image which has a high optical density, is of high quality, and is applicable to the use of projecting an image by a high-definition overhead projector or the like is used. It has become possible to form a recorded image having a high gloss on the surface comparable to that of a silver halide photograph.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a head portion of an inkjet recording apparatus.

FIG. 2 is a cross-sectional view of a head portion of an inkjet recording device.

3 is an external perspective view of a head in which the head shown in FIG.

FIG. 4 is a perspective view showing an example of an inkjet recording apparatus.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keiichi Suzuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (11)

[Claims] 1. An ink jet recording method for performing color recording by ejecting small droplets of cyan, magenta, yellow and black ink from an orifice of a recording head in accordance with a recording signal and adhering them to a recording medium, and having a surface tension of 25. To 35 dyne / cm, a base material and a saponification degree of 75 to 75 provided on the base material.
An ink jet recording method comprising using a recording medium including a coating layer mainly composed of polyvinyl alcohol or a derivative thereof having a polymerization degree of 98 mol% and a degree of polymerization of 100 to 500. 2. The ink jet recording method according to claim 1, wherein the coating layer contains polyalkylene oxide or a derivative thereof. 3. The coating layer contains a hydrophilic acrylic resin which is a copolymer of a vinyl-based monomer having a cationic group and a vinyl-based monomer having a hydrophobic group.
The inkjet recording method described in 1. 4. An ink jet recording method for performing color recording by ejecting small droplets of cyan, magenta, yellow and black ink from an orifice of a recording head in accordance with a recording signal and adhering them to a recording medium to have a surface tension of 25. To 35 dyne / cm, and a substrate and an ink receiving layer provided on at least one surface of the substrate, wherein the ink receiving layer comprises (i) polyvinyl alcohol or a derivative thereof (ii) Polyalkylene oxide or derivative thereof (iii) A recording medium containing a hydrophilic acrylic resin which is a copolymer of a vinyl monomer having a cationic group and a vinyl monomer having a hydrophobic group is used. And an inkjet recording method. 5. The ink jet recording method according to claim 1, wherein the coating layer contains 0.5% or more of an epoxy compound. 6. The inkjet recording method according to claim 1, wherein the substrate is a plastic film. 7. The ink jet recording method according to claim 1, wherein the liquid medium component of the ink is composed mainly of water and a water-miscible glycol or glycol ether. 8. The inkjet according to claim 1, wherein at least two orifices for ejecting ink of each color are provided for each color, and recording is performed by ejecting two or more ink droplets of substantially the same color at the same time. Recording method. 9. The ink jet recording method according to claim 1, wherein small droplets of each color ink are ejected at a frequency of at least 3 KHz or higher. 10. The ink jet recording method according to claim 1, wherein the maximum recording density of at least each color ink is 6 nl / mm ² or more. 11. The ink jet recording method according to claim 1, wherein the ink is ejected by applying thermal energy to the ink.