JPH09263036A - Inkjet image receptor - Google Patents

Abstract

(57) Abstract: The present invention relates to an image receptor used in a full-color inkjet recording system in which the amount of ink applied per unit area is large, and not only the non-printing portion but also the printing portion is photograph-like. The present invention relates to an inkjet image receptor having high gloss and an inkjet image receptor having high transparency that can be used as an OHP sheet. In an ink jet image receptor having an ink image receiving layer provided on at least one surface of a support, the ink image receiving layer contains at least gelatin, and the surface of the ink image receiving layer has a contact angle of 80% by weight with a glycerin aqueous solution. An ink jet image receptor, which is less than a degree. In order to obtain an image receptor, an ink image-receiving layer coating liquid containing at least gelatin is coated on a support at a temperature higher than the gelling temperature of the coating liquid, and then the gelling temperature of the coating liquid is kept in a fluid state. It can be obtained by drying at a higher temperature to form the ink image-receiving layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image receptor used in a full-color ink jet recording system in which the amount of ink applied per unit area is large, and not only the non-printing portion but also the printing portion is photographic-like and strong. The present invention relates to an inkjet image receptor having gloss and an inkjet image receptor having high transparency that can be used as an OHP sheet.

[0002]

2. Description of the Related Art The ink jet recording method is a recording method capable of high-speed printing and multi-color printing with little noise generation. Recently, the performance of ink jet printers has been remarkably improved, and the price is low for personal use. Attention is paid to this method, and it is attracting attention as a recording method that enables easy and inexpensive full-color recording. However, for printers capable of full-color recording, commonly used non-coated paper, matte-coated paper, gloss-coated paper, OHP film, etc. have been commercialized as the image-receiving paper, but the vivid colors The present situation is that a photographic-like image receptor that exhibits various colors is still in the development stage.

Although the above-mentioned gloss coated paper has a glossy feeling as compared with non-coated paper or matte coated paper, since the coating layer is formed of pigment particles having a submicron size, it is not a little visible. At present, no image receptor has been developed that diffuses light and gives a glossy feeling as strong as in a photograph. That is, in order to obtain a glossy feeling like a photograph, as can be seen from the fact that the photographic printing paper is formed by forming the gelatin layer on the resin-coated paper, the ink image-receiving layer is formed of a polymer or resin or a composite thereof. It is preferable that a support having excellent smoothness such as a resin-coated paper or a plastic film is used as the support. When a resin-coated paper or plastic film is used as the support, it is necessary to provide an ink image-receiving layer on the support, unlike paper that can absorb, diffuse, and retain ink. Various characteristics are required for this image receiving layer. First, an ink absorption capacity that can sufficiently absorb the ejected ink droplets is required. Further, in the case of full-color printing, usually three or four different colors of ink are overprinted in a short time, and therefore the ink absorption speed may be high so that the dots do not mix with each other. Desired. next,
Since the dot diameter of the ink is controlled, the wettability with respect to the ink becomes a problem. Other required properties include excellent gloss in the printed portion and non-printed portion, dye fixing property (less bleeding), print density, water resistance and the like.

Various methods have been taken to satisfy the above characteristics. For example, an image receptor is known in which a general synthetic water-soluble polymer or a polymer layer having an affinity for ink is provided on a plastic film having high smoothness. However, the gloss of the printed part is reduced by the dissolution of the polymer layer surface due to the ink solvent, the dye fixability (bleeding) under high humidity due to the water-soluble polymer, and the surface of the polymer layer is weak. There are various problems such as scratches on the printed surface due to the above. In addition, Japanese Unexamined Patent Publication No.
It is also known to form an ink image-receiving layer on transparent PET or white PET only with colloidal silica or alumina sol having a primary particle size shorter than the wavelength of visible light, as described in 199034 and JP-A-6-262844. There is. According to this method, since it has a surface formed of a pigment, spur-like wheel roll marks are less likely to form. However, in this system, the image receiving layer basically absorbs and retains ink only by capillarity, so it is possible to quickly absorb and retain a large amount of ink that is rapidly ejected, but it is achieved. In order to do so, a thick image receiving layer of 30 microns or more is required, which is disadvantageous in cost. In addition, it is technically difficult to apply an inorganic sol having a small particle size uniformly without cracking, and when an ink absorption capacity is required, a thicker image receiving layer is required, which is very technically and costly. It gets harder. Also, Japanese Patent Application Laid-Open
As described in JP-A-89221, an image receptor assembled with alumina sol and acidic method gelatin has been proposed. Basically, gelatin is used as a binder for alumina sol, and an ink mainly composed of inorganic fine particles is used. It is an image receiving layer. Since these image receivers are mainly composed of particles,
In reality, the smoothness of the polymer film such as the gelatin film of photographic printing paper is inferior to that of the glossiness of photographs. Even if a highly absorbent film can be formed with a polymer layer that is not cross-linked, the non-volatile high-boiling point solvent component such as triethylene glycol contained in the ink plasticizes the printing area, etc. There is also a problem that the strength and adhesion are weakened, and roll marks are left on a spur wheel roll for transportation. Further, when a natural polymer such as gelatin is used as the image-receiving layer, a commonly-obtained gelatin film has a poor ink absorbency (speed), and therefore, it is disclosed in Japanese Patent Laid-Open No.
As described in JP-A-2-263084, gelatin is often used as an ink holding layer and as a lower layer of a two-layer structure.

As described above, an ink jet image receptor having a photographic-like strong gloss and an OHP sheet having high transparency are required to have characteristics different from those of conventional non-coated paper or coated paper for ink jet, and technically Is a very difficult recording material.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet image receptor having a high gloss and an OH having high transparency.
To provide a P sheet, more specifically, ink absorption is good, and a printed portion and a non-printed portion have strong gloss,
Good dye fixability, high print density, strong surface strength,
It is an object of the present invention to provide a very photographic-like ink jet image receptor which is not sticky and has good storage stability, and an OHP sheet having high transparency.

[0007]

Means for Solving the Problem As a means for solving this problem, in an ink jet image receptor having an ink image receiving layer provided on at least one surface of a support, the ink image receiving layer contains at least gelatin, and the ink image receiving layer is provided. The surface of the layer has a contact angle of 80 with a 20% by weight aqueous glycerin solution.
It is achieved by an ink jet image receptor characterized by being less than 100 degrees. Further, in an ink jet image receptor having an ink image receiving layer provided on at least one surface of a support, the ink image receiving layer contains at least gelatin, and an ink image receiving layer formed by drying without gelatinizing the gelatin component is formed. It can also be achieved by a characteristic inkjet image receptor. In order to produce the above image receptor, the coating liquid for ink image receiving layer containing gelatin is applied on a support at a temperature higher than the gelling temperature of the coating liquid, and then the gelling temperature is applied in a state where the coating liquid has fluidity. It can be produced by drying at a higher temperature.

Usually, the ink used in the ink jet printer is a water-based ink from the viewpoints of environment and safety, and most of the composition is water. However, it is general that a high boiling point solvent such as glycerin or triethylene glycol is contained in an amount of about 10 to 25% in order to prevent the nozzle from drying. Therefore, the ink image receiving layer must instantly absorb and retain water, glycerin, and the like. Therefore, the surface physical properties of the image receptor are greatly related to the diameter of the ink dots formed by the ejected ink droplets and the circularity of the ink dots, and thus have a great influence on the print quality.

As a result of diligent studies, the present inventors have found that as a surface physical property of the ink receiver, the contact angle has a great influence on the ink absorbability and the printing quality, and in particular, the influence of the contact angle on a 20 wt% glycerin aqueous solution. I found that is big. Evaluating the wettability to water and glycerin, which account for the majority of the ink components, is very significant in order to see the performance of the inkjet image receptor,
In fact, in most cases a good image can be obtained from a receiver having good wettability. In order to evaluate the wettability of such a surface, it is practical, convenient and most preferable to measure the contact angle of the surface of the ink jet image receptor with water, glycerin and a water / glycerin mixed aqueous solution.

The contact angle in the present invention is basically used when it is determined whether or not a certain solid surface is well wetted by a liquid, and the contact angle between the surface of the liquid drop placed on the solid surface and the solid surface. The angle between the tangent line drawn to the droplet at the intersection and the solid surface and containing the liquid is called the contact angle θ. There are also various forms of "wetting", which are broadly divided into extended wetting (wetting when water or alcohol spreads thinly on a glass plate, etc.), immersion wetting (wetting that occurs when paper or cloth is soaked in water). Etc.), adhesion wetting (pointing the wetting and the like that occurs on the contact surface between the two when mercury is placed on the glass surface). Actually, at the moment when the ink droplet is struck on the surface of the image receptor, the above-mentioned wetting is absorbed instantly while being complicatedly entangled.

Usually, the ink jet ink is composed of various components in order to improve the wettability and penetrability of the ink jet image receptor as described above. That is, in addition to water, which accounts for most of the actual ink, colorants (dyes and pigments), high-boiling solvent components such as glycerin and ethylene glycol, and other minor components such as surfactants, defoamers, and rust inhibitors. It is composed of various ingredients. Therefore, when measuring and evaluating the wettability of the surface of the ink jet image receptor by the contact angle, it is necessary to measure the contact angle directly with the ink as described above. However, it was difficult to measure the contact angle because the surface tension of the entire ink was too low. In addition, ethylene glycol (50.21 dyncm ^-1 ) and diethylene glycol (46.97 dyn) contained as high boiling point solvent components in the ink.
cm ^-1 ), triethylene glycol (47.33 dyncm ^-1 )
Wetness such as is difficult to measure for the same reason because the surface tension is too low. However, water (72.75 dyncm ^-1 ) and glycerin (63.40 dyncm), which are the most abundant components in the ink components, are used.
The surface tension of ^-1 ) is specifically high, which is very convenient for measuring the contact angle, and wetting of the image receptor surface can be modeled from the contact angle.

As a result of earnest studies in the present invention, in an image receptor containing at least gelatin having a surface having a contact angle θ with a 20% by weight aqueous glycerin solution of 80 degrees or less, the ink to be shot spreads to an appropriate size. It has been found that the images obtained are very good.

In addition, recent inkjet color printers have helped with the rapid price reduction and high performance of computers, providing an environment in which full-color images can be output, so that not only conventional characters and multicolor graphics but also photographs can be taken. It has become possible to output full-color images as described above, and high image quality and high definition are desired. For this reason, the roundness of dots is becoming important, and it is difficult in principle to obtain the roundness of dots in a conventional image receptor composed of an inorganic pigment such as pulp or silica. However, in the case of an image receptor having a contact angle θ of 80 degrees or less and containing at least gelatin, the ejected ink droplets can be appropriately swiftly spread to form dots having a high roundness.

In the present invention, as one of the methods for obtaining the image receptor having the above-mentioned surface, at least gelatin is contained,
The gelatin component could be obtained by the image-receiving layer formed by drying without gelling. It is known that gelatin forms various films having different surfaces and internal structures depending on whether the aqueous solution is dried without gelation or after being gelled and then dried. It was possible to obtain an inkjet image receptor that solved the above problem. That is, it is the difference between a gelatin film formed without passing through a gel and a gelatin film formed via a gel. The former is a film obtained by drying an aqueous solution of gelatin (gelatin sol) under conditions that do not cause gel formation, for example, keeping it at a high temperature of 60 ° C or higher, and the latter is a gel sol that is dried after gelling. It is a film obtained by.
In this way, a gelatin film having different characteristics is formed depending on whether the gel film is dried after gelling or not gelled.

The gelatin will be described in detail below.
Generally, if the gelatin sol has a concentration of 1% or more, it is solidified into a gel when kept at a temperature of 10 ° C. The change between the sol and the gel is reversible to some extent, the temperature at which the sol solidifies to form a gel is called the freezing point (gelation temperature), and the temperature at which the gel dissolves to form the sol is called the melting point. Generally, in a linear polymer substance, melting and solidification are significantly affected by history, and the melting point and the solidification point often do not match. Gelatin is also made of linear polymers, and this is the case. As described above, the difference between the melting point and the freezing point is usually about 5 to 8 ° C., and at a relatively low concentration of 5% or so, at a temperature higher than 40 ° C., it becomes almost a single molecule random coil shape. Therefore, it is considered that there is almost no crystalline portion.

Gelatin is an ampholytic substance composed of 18 kinds of amino acids, and glycine accounts for about 1/3 of the amino acid composition. Gelatin has approximately 64-65% of non-polar groups such as methylene chains contained in glycine residues, which act as lipophilicity and are more than the remaining hydrophilic groups. Therefore, since hydrophilic groups are bound to each other during gel formation, the lipophilic effect may be significant. In fact, the surface of gelatin gel containing water and the gel-dried product are dried. It is well known that the surface of the coating film obtained in this way becomes considerably water repellent.
On the other hand, the surface of the film formed without gelatinizing gelatin does not bond to each other due to hydrophilic groups, so the water repellency is inferior to that of the film surface obtained by drying after gelling, and the hydrophilic surface is It is formed.

Therefore, the gelatin film formed without gelation forms a very wettable surface. It is considered that when this was used as an inkjet image-receiving layer, the ink droplets spread moderately due to the good wettability of the surface, and an image-receiving layer with good absorbency was obtained.

Since the ink jet image receptor in the present invention uses gelatin, the unprinted portion is irrespective of the gelatin film formed without passing through the gel or the gelatin film formed via the gel. The surface is not sticky regardless of the print area. Usually, the ink-jet image receptor composed of other natural polymers or synthetic polymers absorbs the ink in the printed area, but the moisture evaporates by drying, but the high boiling point solvent such as glycerin remains on the surface. In many cases, the low molecular weight substance of the image receiving layer melts into the ink and becomes sticky. However, because gelatin contains hydrophobic and hydrophilic groups in a well-balanced manner as described above, it can also absorb and retain non-volatile components such as glycerin, so it swells in ink components, etc. Since it does not stick, the feature is that the printed surface is not sticky.

For the above reasons, since the ink image receiving layer containing gelatin is less sticky, OH which requires high transparency.
When the ink image-receiving layer of the P sheet is used, it is not necessary to sprinkle inorganic or organic fine particles for preventing blocking on the surface of the image-receiving layer, and a highly transparent image-receiving layer formed of only a polymer can be secured.

Further, a gelatin film formed without passing through a gel and a gelatin film formed via a gel
The internal structure of the film is also quite different. That is, the film formed via the gelatin gel inherits the gel properties as it is, and the gelatin gel has a crystal part (helix structure) that is partially and orderly arranged from wide-angle X-ray diffraction and specific rotation. It has a three-dimensional mesh structure consisting of an amorphous part (random coil structure) that connects them. This gelatin gel differs in the internal structure of the gel formed under various conditions during gelation from gelatin sol. The internal structure of the gel gradually changes due to changes in temperature and the passage of time. That is, 0 ° C
The melting point of the gelled product at 15 ° C. is higher than that of the gelled product at 15 ° C. This is because in the latter case, gelation is slower and the number of unstable bonds is smaller. On the contrary, in the former case, a large number of small crystal parts arranged in a spiral shape are formed.

The internal structure of the gelatin film formed without passing through the gel used in the present invention is completely opposite to that of the gelatin film formed via the above-mentioned gel, and it has almost no crystal part and is It is considered that the crystal part occupies most. Because the internal structure is completely different,
It is considered that the gelatin film formed without passing through the gel and the gelatin film formed via the gel have different physical properties. Although the physical properties of the surface are described above, the swelling degree to other water, hygroscopicity and jelly strength are generally different. The reasons for the degree of swelling and hygroscopicity are not clear, but generally gelatin films formed via gel are higher, and generally jelly strength is also stronger.

It is unlikely that such a difference in the internal structure contributes greatly to the ink droplets ejected in a few milliseconds, and it is considered that the surface characteristics of the image receptor are dominant. This is especially the case with respect to image quality (especially absorption rate is dominant), and the gelatin film formed without passing through the gel clearly has better image quality.

Therefore, in the present invention, various methods are used to obtain an ink jet image receptor of a gelatin film formed without passing through such a gel. Hydrogen bonds, van der Waals forces, etc. are considered as the bonding modes for forming gels, and hydrogen bonds are actually the main force of gel formation, such as urea, salicylic acid, and KS.
A gelatin film formed without passing through a gel can be obtained by adding a reagent that significantly inhibits hydrogen bonding such as CN or n-propanol to a gelatin sol solution. Also, gel formation is greatly affected by pH,
Gelatin formed without passing through a gel by a gelatin sol whose pH is shifted from the isoelectric point of the gelatin
You can also get a film.

In the present invention, the most simple and reliable method for obtaining a gelatin film formed without passing through a gel is to dry a gelatin sol having a temperature not lower than the gelling temperature as it is under a drying condition not lower than the gelling temperature. Is most preferred. The gelling temperature of gelatin is generally about 35 ° C.
The effect of concentration, pH and salt is considered to form gelatin gel from gelatin sol. Normally, it is about 35 with or without alkali method gelatin, acid method gelatin and desalting.
A gelatin film formed without passing through a gel can be obtained at a gelatin sol temperature of ℃ or higher and a drying temperature.
Preferably, the drying temperature is 5-8 ° C higher than the gelling temperature, the melting point of gelatin or higher, that is, 40 ° C or higher, and more preferably 60 ° C or higher. However, when the coated surface is cooled to room temperature after coating at the gelling temperature or higher, that is, when the gelling temperature is lower than or equal to the gelling temperature, gelatinization of gelatin proceeds, and then at a drying temperature higher than the gelling temperature or higher than the melting point. Even when dried, the moisture gradually evaporates and the concentration rises, making it difficult for gelatin molecules to move.Therefore, the change from gelatin gel to sol is not sufficient, and it is partially formed via gel. As a result, gelatin is generated, and the ink absorption performance is deteriorated.

Therefore, in the case of obtaining an image receptor containing at least gelatin in the present invention, the coating solution containing gelatin is dried at a temperature higher than the gelling temperature of the coating solution and immediately above the gelling temperature. By doing so, an ink jet image receptor that solves the problems of the present invention can be obtained. The drying temperature may be affected by the various effects described above and may vary depending on other water-soluble polymers to be mixed, but as described above, if the temperature is about 60 ° C or higher, the contained gelatin does not pass through the gel to receive the image. I found that I could get a body.

As the gelatin used in the present invention, various gelatins can be used. Basically, as the gelatin used in the present invention, any gelatin can be used as long as it is made from animal insoluble collagen.
Gelatin made from collagen obtained from pig skin, cow skin, cow bone or tendon is preferable. Further, the type of gelatin is not particularly limited, but alkali method (lime treatment) gelatin, acid method gelatin, those desalted by ion exchange, those not desalted, and further gelatin derivatives (for example, JP-B-38- No. 4854, same as 39-551.
4, gazette 40-12237, gazette 42-2
6345, U.S. Pat. Nos. 2,525,753, 2,594,293 and 2,614,928,
No. 2763639, No. 3118766, No. 3132945, No. 3186846, No. 3312553, and British Patent No. 8614.
The gelatin derivatives described in JP-A No. 14 and JP-A-1033189, etc.) can be used alone or in combination.

However, the gelatin used more preferably in the present invention is acidic gelatin. Usually, for silver salt photographs, desalted alkali method gelatin is generally used in consideration of the influence on silver halide etc. Acid method gelatin is used for dye water resistance and film strength (jelly strength). Is superior to other gelatins in. The following can be considered as a reason for this.

Gelatin is usually obtained by subjecting animal insoluble collagen to alkali treatment or acid treatment. Approximately 37% of carboxyl residues are amidated in collagen, but are strongly hydrolyzed by alkali treatment, so that free carboxyl groups are generated. On the other hand, the acid treatment hardly undergoes amide hydrolysis, and almost the same amide as collagen remains. Therefore, the acidic method gelatin is a cationic polymer as compared with the alkaline method gelatin. Further, usually, a water-soluble dye is used as a colorant of an ink for an ink jet printer, and the dye is an acidic dye which generally imparts water solubility by introducing a sulfonic acid group or a carboxylic acid group into a dye molecule. , A disperse dye. Therefore, an anionic dye is fixed to the cationic gelatin. Regarding the film strength, the acidic method gelatin is generally superior, and the molecular weights of the alkaline method gelatin and the acidic method gelatin are generally different due to the difference in the treatment from the above-mentioned collagen. The number average molecular weight of the former is about 40,000 to 70,000, and that of the latter is 650,000 to 90,000, which is considered to directly appear as a difference in film strength (jelly strength).

Therefore, the gelatin preferably used in the present invention has the above-mentioned characteristics, and acidic method gelatin having a number average molecular weight of 60,000 or more and an isoelectric point of pH 5 to 9 is preferable.

The gelatin film formed without passing through the gel of the present invention is basically structurally unstable as compared with the gelatin film formed via the gel. Most of the gelatin films formed without passing through the gel are non-crystalline random coils as described above. This causes a sol-gel transition in an environment such as high humidity, and changes to a more stable helix structure (crystal part). However, in an absolutely dry state, the polymer chains hardly move and such a change does not occur. A hard copy medium such as an ink jet image receptor may be placed in various harsh environments, and of course the influence of humidity must be taken into consideration. Therefore, there is a concern about the storage stability of the gelatin film formed without passing through the gel due to humidity.

Therefore, in the present invention, an ink jet image receptor obtained by hardening gelatin is provided in order to prevent such a change with time in humidity, further increase the film strength, and obtain a film insoluble in water. It has been found to be very effective. That is, the random coil state of the gelatin film formed without passing through the gel is fixed by the dura. As such a hardening method, various hardening methods used in silver salt photography and the like can be used.

As the hardener used in such a hardener reaction, the following organic hardeners can be mentioned.
Aldehyde hardeners, specifically formaldehyde, glyoxal, succinaldehyde, glutaraldehyde, dialdehyde starch, polyacrolein, N-methylol and acetal hardeners are condensates of ethylene glycol and glyoxal, succinaldehyde and ethanol Condensates, epoxy hardeners, aziridine hardeners, dichloro-S-triazine hardeners, mucochloric acid hardeners, mucochloric acid hardeners, acid halide hardeners of active halogen hardeners, Benzyl halide type, acyl compounds having a halogen at the carbon at the α-position, active olefin type hardeners vinylsulfone type, acryloyl type, bismaleimide type, carbodiimide type hardener, isoxazolum type hardener, metasulfonic acid Ester hardener, active ester hardener, etc. It can be used.

Of these, epoxy-based hardeners and the like are preferable as hardeners that are inexpensive and generally easy to obtain and popular because of their properties such as hardenability and pot life, and the following compounds are preferably used. Sorbitol polyglycidyl ether, sorbitan polyglycidyl ether,
Polyglycerol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, triglycidyl tris (2-hydroxyethyl) isocyanate, trimethylolpropane polyglycidyl ether, resorcin diglycidyl ether, neopentyl glycol diglycidyl ether, 1 , 6-
Hexanediol diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, adipic acid diglycidyl ether, ortho-
Examples thereof include phthalic acid diglycidyl ether, hydroquinone diglycidyl ether, bisphenol S diglycidyl ether, terephthalic acid diglycidyl ether, and dibromoneopentyl glycol diglycidyl ether.

Further, the aziridine type hardener has little pH dependency and can be preferably used, and the following compounds can be mentioned.
Trimethylolpropane-tri-β-aziridinylpropionate, tetramethylolmethane-tri-β-aziridinylpropionate, N, N′-diphenylmethane-4,4-bis (1-aziridinecarboxamide) ,
N, N'-hexamethylene-1,6-bis (1-aziridinecarboxamide), N, N'-toluene-2,4-
Examples thereof include bis (1-aziridinecarboxamide), triethylenemelamine and bisisophthaloyl-1- (2-methylaziridine).

Although there are many inorganic hardeners, generally, polyvalent metal salts such as alum and chrome alum often harden gelatin. It has long been known that gelatin containing dichromate is hardened by light, and this method can also be used.

There are various methods for hardening gelatin as described above. This is due to the type and number of reaction points of gelatin, which is composed of 18 kinds of various amino acids in total.

The gelatin film formed without passing through the gel in the present invention is slightly inferior in swelling degree to the gelatin film formed via the gel, but has sufficient absorption as an ink jet image receptor. Has capacity (swelling degree). Therefore, in this case, since the swelling degree is 200% or more, the ink has a sufficient capacity to absorb the ink. Therefore, it is preferable to add the hardener so that the swelling degree is higher than this.

In the present invention, the hardener used most preferably is an aziridine type hardener or an epoxy type hardener, and its addition amount is based on the gelatin solid content based on the change with time and swelling degree of the gelatin film. And an addition amount of 0.1 to 10% by weight is preferable. Further, the addition amount of 0.3 to 5% by weight is more preferable.

The ink image-receiving layer containing at least gelatin in the present invention can be obtained by mixing various water-soluble polymers or alcohol-soluble polymers with the gelatin, grafting on the gelatin, or forming two layers. As the polymer preferably used together with gelatin in this way, carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, phthal cellulose acetate, carrageenan, furceleran, gum arabic, guar gum, locust bean gum, transgant gum,
Pectin, cyclodextrin, glue, collagen protein, casein, pullulan, sodium alginate, polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, polyacrylic acid, sodium polyacrylate and the like can be mentioned. When mixed or grafted, the content of gelatin is 30 with respect to the whole polymer.
% By weight or more is preferred.

In the present invention, various supports can be used as long as they have flexibility so that they can be passed through a commercially available ink jet printer. For example, among uncoated and coated papers with adjusted size, pulp, and synthetic resin materials, synthetic paper that looks like paper, inorganic fiber paper made of glass fiber or ceramic fiber, non-woven fabric, Examples thereof include colored resin sheets.

However, as the various supports used in the present invention, a white opaque support is suitable for observing an image with reflected light, and in order to give the texture of a color photograph like a photographic printing paper. A resin-coated paper or a white plastic film is preferably used. Since high smoothness is required for the surface of the image receiving layer of the ink jet image receptor, one having high smoothness is more preferable. This is completely different from the presence of a coloring agent (dye) in the gelatin layer as in photographic printing paper for silver salt photography, and the surface smoothness of an inkjet recording sheet in which a dye is present near the surface of the image receiving layer is particularly It becomes a problem. Therefore, the smoothness of the support becomes a problem, and by providing an image receiving layer on a polyester film or resin-coated paper having a 60 degree gloss of 40 or more according to the JIS-Z-8741 specular gloss measurement method, the JIS
It was found by the specular gloss measurement method of -Z-8741 that an ink jet image receptor having a surface gloss of 60 or more and 80 or more can be obtained.

The opaque support preferably used in the present invention is the above-mentioned white polyester film or resin-coated paper, but the one suitable for the texture (touch feeling) equivalent to that of color photographic paper is photographic paper. It is a resin-coated paper which is the same support. Recent advances in the field of color hard copy have been remarkable, and the image quality is close to that of silver halide photography. However, in spite of its excellent image quality such as the sublimation thermal transfer method, when it is evaluated by a photographic expert, it is evaluated as a recording material which is completely different from silver halide photography. It is thought that the main reason is the difference in the feel of the recording material when it is picked up. If you only observe the recorded images from a distance, you will receive a very good evaluation,
Once it is touched and observed, it loses its reputation and becomes a recording material that is not similar to silver salt photography.

The thickness of the resin-coated paper used in the present invention is
In the case of inkjet recordings printed by a printer,
The size of the resin-coated paper is preferably 200 μm or more, since it is different from the size of a normal photograph and becomes large like A4 size, so that a support having a rigidity is required.

The base paper of the resin-coated paper used in the present invention is
A smooth base paper as commonly used is preferred. As the pulp constituting the base paper, a natural pulp, a recycled pulp, a synthetic pulp, or the like is used alone or in combination of two or more. This base paper includes sizing agents, paper strength agents, fillers, antistatic agents, optical brighteners, which are generally used in papermaking,
Additives such as dyes are blended. Further, a surface sizing agent, a surface strengthening agent, a fluorescent whitening agent, an antistatic agent, a dye, an anchoring agent and the like may be applied on the surface.

The base paper is preferably one having good surface smoothness, such as being compressed by applying pressure with a calender or the like during or after paper making, and the basis weight thereof is 30 to 250 g / m 2.
² is preferred. It is preferably 100 to 250 g / m ² .

In the present invention, the resin mainly used for the resin-coated paper is a polyethylene resin, and as its kind, low density polyethylene, medium density polyethylene, high density polyethylene or a mixture thereof can be used. The low-density polyethylene referred to here has a density of 0.915 to 0.9.
It is 30 g / cm ³ and is usually produced by a high pressure method. On the other hand, high density polyethylene has a density of 0.
It is 950 g / cm ³ or more and is usually produced by a low pressure method or an intermediate pressure method. As these polyethylene resins, those having various densities and melt flow rates can be used alone or as a mixture of two or more thereof.

The resin layer of the resin-coated paper according to the present invention may have a single layer structure or a multilayer structure of two or more layers. Also in this case, the above polyethylene resins may be used alone or in combination of two or more. Further, the respective layers of the multilayer may have the same composition or different compositions. As a method for forming a resin layer having a multi-layer structure, either a coextrusion coating method or a sequential coating method may be adopted.

The thickness of the coating resin layer of the resin-coated paper in the present invention is not particularly limited, but it is generally 5 to 50 μm and coated on only the front surface or both front and back surfaces.

In the resin of the resin-coated paper according to the present invention,
White pigments such as titanium oxide, zinc oxide, talc and calcium carbonate, fatty acid amides such as stearic acid amide and arachidic acid amide, fatty acid metal salts such as zinc stearate, calcium stearate, aluminum stearate and magnesium stearate, Irganox 1010. , Antioxidants such as Irganox 1076, blue pigments and dyes such as cobalt blue, ultramarine blue, cesianian blue and phthalocyanine blue, magenta pigments and dyes such as cobalt violet, fast violet and manganese purple, optical brighteners, ultraviolet rays Various additives such as an absorber can be added in an appropriate combination.

The resin-coated paper used as the support in the present invention is produced by a so-called extrusion coating method in which a heat-melted polyethylene resin is cast on a running base paper. Further, in order to improve the adhesion between the resin and the base paper, it is preferable that the base paper is subjected to an activation treatment such as a corona discharge treatment and a flame treatment before coating the resin on the base paper. The surface (surface) of the support on which the ink image-receiving layer is applied has a glossy surface, a matte surface, and the like, depending on the application, and a glossy surface is particularly preferably used. It is not always necessary to coat the resin on the back surface, but it is preferable to coat the resin from the viewpoint of curling prevention. The back surface is usually a matte surface, and the front surface or both the front and back surfaces can be subjected to activation treatment such as corona discharge treatment and flame treatment as required.

The support in the present invention includes an antistatic agent,
Various back coat layers can be applied for transportability, curl prevention agents and the like. An inorganic antistatic agent, an organic antistatic agent, a hydrophilic binder, a latex, a curing agent, a pigment, a surfactant and the like can be appropriately combined and added to the back coat layer.

Next, as another suitable opaque support, a white plastic sheet, the following materials can be used. For example, a film made of polyester, polyolefin, polyamide, polyesteramide, polyether, polyimide, polyamideimide, polystyrene, polycarbonate, poly-P-phenylene sulfide, polyether ester, polyvinyl chloride, poly (meth) acrylic acid ester, etc. is preferable. It is possible to use a copolymer or a blend of these, or a cross-linked product thereof. More preferably, polyester is preferable, and polyethylene terephthalate (hereinafter PE
(Referred to as T) is excellent in smoothness, dimensional stability, heat resistance, strength, high rigidity, chemical resistance, moisture resistance and water resistance, and is very preferable.

As the opaque support, a white PET film obtained by kneading a white pigment such as titanium oxide, zinc oxide, talc, or calcium carbonate into the PET film can be used as the support. Further, a foamed PET film obtained by foaming and whitening a PET film can also be used as a support.

The raw material used for the PET film in the present invention is a thermoplastic polyester, typically PET which is condensation-polymerized from terephthalic acid or dimethyl terephthalate and diethylene glycol. Further, by changing or combining an acid component and a glycol component, polymerization is carried out to obtain polyesters having different basic properties such as melting point and glass transition temperature, which can also be used as a PET film raw material.

Generally, unstretched amorphous PET film has poor heat resistance and expands up to 70 ° C. near the glass transition temperature.
At higher temperatures, low temperature crystallization occurs and volume shrinkage occurs. The PET film used in the present invention is produced by a sequential biaxial stretching method or the like, and has a crystallinity of 40% or more and a stretching ratio of 2.5 times or more, and has smoothness, dimensional stability, heat resistance, strength, high rigidity, It is preferable to use a PET film having characteristics such as chemical resistance and moisture resistance.

In addition, the PET of the inkjet printer
In consideration of the transportability of the film, silica or titanium oxide, calcium carbonate, aluminum oxide or other oxides, or inorganic salt in the polymerization process of polyester, or in the molding process, the average particle size of 0.1 ~ 10μm inert 0.0 particles
PET containing 1 to 0.5% by weight is formed into a sheet, melt-extruded, biaxially stretched, and heat-treated to form particles of 0.1 to 0.5% by weight.
You may use the PET film etc. which improved the slipperiness by disperse | distributing on a film surface as a particle | grain of 2 micrometers.

The present invention also relates to a highly transparent ink-jet image receptor that can be used as an OHP sheet, but even in an image receptor that requires translucency such as an OHP sheet, only the composition of the ink image-receiving layer is used. Not only that, the properties of the support are also important. Regarding the light transmittance when used as an OHP film, the haze (cloudiness value) is closer to the human sense than the total light transmittance, and the ink absorption layer of the present invention is
By providing the transparent support having a haze (cloudiness value) of 3.0 or less by SK-7105 on at least one surface, a highly transparent inkjet image receptor could be provided.

The haze of the ink jet image receptor used as an OHP sheet is the haze (cloudiness) according to JIS-K-7105 of the ink jet image receptor in which the ink image receiving layer is provided on the support. (Value) is preferably 5.0 or less.

The haze (cloudiness value) is measured by using an integrating sphere type light transmittance measuring device to measure diffuse transmittance and total light transmittance, and is expressed by the ratio thereof according to JIS-K-7.
105.

As the plastic sheet which is a suitable transparent support for OHP used in the present invention, various transparent sheets made of the same material as the white plastic sheet of the opaque support can be used. Also, like the white plastic sheet, polyethylene terephthalate is very suitable from the viewpoint of the haze (cloudiness value), and has smoothness, dimensional stability, heat resistance, strength, high rigidity, chemical resistance, moisture resistance and moisture resistance. Is also excellent and very preferable. OHP
The thickness of the support to be used in the image receptor such as a sheet, which is required to have a light-transmitting property, is not particularly limited, but it is preferably about 50 to 200 μm in view of handling property and paper passing property of a printer.

The transparent support in the present invention may be provided with an anchor layer for the purpose of improving the adhesiveness between the ink image-receiving layer and the support. For the anchor layer, a hydrophilic binder, a solvent-soluble binder such as butyral, a latex, a curing agent,
A pigment, a surfactant and the like can be added in an appropriate combination.

On the transparent support, various back coat layers are coated for the antistatic property, the transport property, the anti-curl property, the writing property, the sizing property, etc. within a range that does not increase the haze (cloudiness value). You can In the back coat layer, an inorganic antistatic agent, an organic antistatic agent, a hydrophilic binder, a latex,
A curing agent, a pigment, a lubricant, a surfactant and the like can be added in an appropriate combination.

As described above, the ink jet image receptor of the present invention, in which the surface of the ink image receptor layer has a contact angle of 80 degrees or less with a 20 wt% glycerin aqueous solution, basically contains at least gelatin on the support, This is achieved by the ink image-receiving layer formed by drying the gelatin component without gelling. Therefore, when gelatin sol is applied, it cannot be applied unless it has fluidity. That is, the gelatin coating solution must be maintained above the temperature at which the gelatin sol does not gel. The temperature is preferably about 35 ° C. or higher, and the coating liquid temperature must be kept above this temperature during coating. Furthermore, a coating method in which the drying step is performed immediately after coating is preferable, and ordinary high temperature drying may be used as long as the temperature can be maintained. Therefore, various coating methods can be used,
For example, bar coater, air knife coater, blade coater, roll coater, gravure coater, microgravure coater, fountain reverse coater, spray coater, curtain coater, E-bar coater,
Any method such as a comma coater may be used and is not particularly limited.

Also, if the drying method is 40 ° C. or higher, the water and solvent are sufficiently evaporated under the drying conditions such that the resin-coated paper or plastic film of the support does not hinder heat deterioration and the like, and a film is formed. Any drying method will do. For example, a hot air drying furnace, a drying drum, or the like can be used. The dry coating amount of 7 g / m ² or more is preferable for the ink image-receiving layer in the present invention. If it is less than 7 g / m ² , the ink cannot be sufficiently absorbed and the ink overflows, and when the color mixture is ejected, different inks are mixed not as dots but as droplets, which often causes a problem that a good color image cannot be obtained. . Further, the upper limit of the coating amount of 7 g / m ² or more depends on the drying ability of the coater and the cost and does not cause a problem characteristically as an inkjet image receptor.

[0065]

EXAMPLES Next, the present invention will be specifically described by way of examples, but the invention is not limited thereto.

Example 1 11.8 g of ion-exchanged water was dispersed with 11.1 g of acidic gelatin (isoelectric point 7.8, jelly strength 350, water content 10% by PAGI method), and the mixture was allowed to stand for about 3 hours to give gelatin. Swell thoroughly with water. After that, the gelatin dispersion is about 40 ° C.
To dissolve it into a gelatin sol having a solid content of 10% by weight. An epoxy hardener ethylene glycol diglycidyl ether (0.1 g, 1% by weight based on the solid content of gelatin) was added thereto to prepare a coating liquid. Apply this to a coating temperature of about 4
The coating liquid at 0 ° C. is applied onto a 220-μm-thick resin-coated paper having a 60 ° gloss of 50 and having a gloss of 50 with a wire bar so that the wet weight is 100 g / m ² . Immediately after the applied liquid is still fluid, 80
It was dried for about 10 minutes by a hot air dryer at ℃. Thereafter, the film was heated at a temperature of 40 ° C. under low humidity for one day to allow the epoxy hardener to sufficiently harden to obtain an inkjet image receptor having a dry coating amount of about 10 g / m ² .

Example 2 An ink jet image receptor was obtained in the same manner as in Example 1, except that the drying temperature was changed to 60 ° C.

Example 3 An ink jet image receptor was obtained in the same manner as in Example 1 except that no hardener was added.

Example 4 An ink jet image receptor was prepared in the same manner as in Example 1 except that an aqueous subbing treatment having a 60 degree gloss of 30 and a resin-coated paper having a thickness of 220 microns was used as a support. Obtained.

Example 5 The hardener of Example 1 was changed to an aziridine-based hardener tetramethylolmethane-tri-β-aziridinyl propionate to obtain 0.1 g (1% by weight based on the solid content of gelatin). ) An inkjet image receptor was obtained in the same manner as in Example 1 except that the addition was performed.

Example 6 An ink jet image receptor was obtained in the same manner as in Example 1 except that an aqueous undercoated white PET sheet having a 60 degree gloss of 80 and a thickness of 125 microns was used as the support. .

Example 7 An ink jet OHP sheet was obtained in the same manner as in Example 1 except that a 125 μm thick aqueous subbed transparent PET sheet was used as the support.

Comparative Example 1 11.1 g of acid-processed gelatin (isoelectric point 7.8, jelly strength 350, water content 10% by PAGI method) was dispersed in 88.9 g of ion-exchanged water, and the mixture was allowed to stand for about 3 hours to prepare gelatin. Swell thoroughly with water. After that, the gelatin dispersion is about 40 ° C.
Was dissolved, and a gelatin sol having a solid content concentration of 10% by weight was used as a coating liquid. A coating solution having a coating temperature of about 40 ° C. was applied onto a water-subbed 220-micron-thick resin-coated paper having a gloss of 60 degrees and a gloss of 30 with a wire bar so that the wet weight was 100 g / m ² . Apply. Room temperature 25 ° C, humidity 55%
When placed in the RH environment, the gelatin layer lost fluidity and gelled completely in about 10 minutes after coating. Then, it was dried with a hot air dryer at 30 ° C. to obtain an inkjet image receptor having a dry coating amount of about 10 g / m ² .

Comparative Example 2 In Comparative Example 1, the applied coating liquid was dried by a hot air dryer at 30 ° C. while still being fluid to obtain an ink jet image receptor having a dry coating amount of about 10 g / m ² . .

Comparative Example 3 An ink jet image receptor was obtained in exactly the same manner as in Comparative Example 1, except that the drying temperature was 60 ° C.

Comparative Example 4 Ink image-receiving was carried out in the same manner as in Comparative Example 1, except that 0.1 g (1% by weight based on the solid content of gelatin) of the epoxy hardener ethylene glycol diglycidyl ether was added to the coating liquid. A body was obtained, which was heated at a temperature of 40 ° C. under low humidity for one day to allow the hardening by the epoxy hardener to proceed sufficiently.

Comparative Example 5 An ink jet image receptor was prepared in the same manner as in Comparative Example 1 except that a 220-micron-thick resin-coated paper having a 60 degree glossiness of 50 and an aqueous undercoat treatment was used as the support. Obtained.

Comparative Example 6 An ink jet image receptor was prepared in the same manner as in Comparative Example 4 except that a 220 μm thick resin-coated paper having a 60 ° gloss of 50 and subjected to an aqueous subbing treatment was used as the support. Obtained.

Comparative Example 7 In Comparative Example 1, the 60 ° glossiness was 80 as the support,
An inkjet image receptor was obtained in exactly the same manner except that a white PET film having a thickness of 125 μm and subjected to an aqueous undercoating treatment was used.

Comparative Example 8 An ink jet image receptor was obtained in the same manner as in Comparative Example 1 except that a transparent PET film having a thickness of 125 μm and subjected to an aqueous undercoating treatment was used as the support.

Comparative Example 9 10 g of polyvinyl alcohol (PVA-117 manufactured by Kuraray Co., Ltd.) was dissolved in 90 g of ion-exchanged water to prepare a coating solution. This was subjected to an aqueous subbing treatment having a 60 degree glossiness of 50,
220 micron thick, wet weight on resin coated paper 1
Apply with a wire bar so that it will be 00g / m ^2, and
It was dried in a hot air dryer at 0 ° C. for about 10 minutes to obtain an inkjet image receptor having a dry coating amount of about 10 g / m ² .

Comparative Example 10 10 g of polyvinylpyrrolidone (K-90, manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 90 g of ion-exchanged water to prepare a coating solution. This was subjected to an aqueous subbing treatment having a 60 degree glossiness of 50,
220 micron thick, wet weight on resin coated paper 1
Apply with a wire bar so that it will be 00g / m ^2, and
It was dried in a hot air dryer at 0 ° C. for about 10 minutes to obtain an inkjet image receptor having a dry coating amount of about 10 g / m ² .

Table 1 shows Examples 1 to 7 and Comparative Examples 1 to 10 described above. The glossiness of the support shown in Table 1 was measured by a gonio gloss meter (VES-300A manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS Z 87.
According to the specular glossiness measuring method of No. 41, the specular glossiness is obtained at an incident angle of 60 degrees and a light receiving angle of 60 degrees.

[0084]

[Table 1]

Evaluation The ink jet image receptor thus obtained was evaluated for printing and other evaluations. For printing evaluation, a bubble jet printer BJC-600J made by Canon Inc. was connected to a personal computer PC-9801BX made by NEC Corporation, and various patterns (yellow, magenta, cyan, black, and mixed colors of blue, green and red) were mixed. Solid printing) was recorded in glossy paper mode.

The evaluation methods of the evaluation items in Table 2 below and the definition of the evaluation results are as follows.・ Contact angle: Ion-exchanged water / glycerin = 20/20 in weight ratio 20
The contact angle to the aqueous solution of glycerin% was measured by FACE automatic contact angle meter CA-Z type manufactured by Kyowa Interface Science Co., Ltd. The measurement method is completely automatic, and the surface temperature is 20 ° C for each 20
The contact angle was calculated by measuring the number of times and calculating the average. -Image quality Visual judgment of solid portions for each single color of yellow, magenta, cyan and black and mixed colors thereof. ○: single color,
A uniform solid that does not overflow the ink in both colors. Δ: The solid of mixed colors has a slight overflow of ink. ×: Both single color and mixed color have more overflow of ink. -Density of solid area The optical density of the solid area of black was measured by a Macbeth densitometer for reflection.・ Glossiness Deflection gloss meter (VES-300A made by Nippon Denshoku Industries Co., Ltd.)
The specular glossiness of the solid black portion was determined at an incident angle of 60 degrees and a light receiving angle of 60 degrees according to the specular glossiness measuring method of JIS-Z-8741.・ Film strength After printing, visually judge the roll marks on the non-printed part and the printed part by the spur wheel roll. ：: No roll mark is observed at all in the non-printed portion and the printed portion. Δ: Roll marks are observed only in the print area. ×: Roll marks are observed on the entire surface of both the non-printed portion and the printed portion.・ Water resistance of the film Drop water drops on the non-printed area and wipe off with a tissue after 5 minutes to visually judge the state of the layer surface. ：: There is no melting or peeling of the ink image receiving layer. Δ: The ink image receiving layer was slightly dissolved, but there was no problem in use. X: The ink receiving layer is completely melted or the ink image receiving layer is peeled from the interface with the support.・ Dye fixability (high humidity bleeding) Ink drops (dots) on a 2.5 × 2.5 cm ² square
Are printed in black so that they are independent of each other, and the optical density thereof is measured by a reflection or transmission Macbeth densitometer. Next, after leaving the printed sample in a high temperature and high humidity environment of 40 ° C. and 80% RH for 24 hours, the optical density of the printed portion is measured again to calculate the bleeding rate. Bleeding rate (%) = (optical density of reflection or transmission after bleeding / optical density of reflection or transmission immediately after printing) x 100 ・ High humidity storage property Non-printed sample of white background at 40 ° C, 80% RH high temperature and high humidity After left in the environment for 3 days, the solid color of each color is printed in the same way as the image quality evaluation, and the printing evaluation is performed for each single color of yellow, magenta, cyan, and black and their mixed color before being left in the environment. Visual judgment was made by comparing with the image quality (image quality of the evaluation item). ：: The image quality hardly changes. Δ: Image quality slightly changed and slightly deteriorated. X: The image quality changed and deteriorated.・ Sticky After hand oil has been thoroughly washed off with soap, the surface of the non-printed inkjet image receptor (white background) and the printing area (B
A black solid portion was printed with JC-600J), and the sticky feeling was evaluated by touching with a finger. ◯: There is no sticky feeling in both printed and non-printed areas. Δ: The printed part has a sticky feeling, but the non-printed part does not have a sticky feeling. X: There is a sticky feeling in both the printed portion and the non-printed portion.・ Haze (cloudiness value) A gloss meter made by Nippon Denshoku Industries, NDH-300A is used.
The haze (cloudiness value) of the non-printed portion was measured according to the method of JIS-K-7105. When used as an OHP sheet, the haze of the non-printed portion is preferably 5.0 or less,
When it exceeds, the projected image becomes dark.

[0087]

[Table 2]

[0088]

As is apparent from the examples, the ink absorption is good and the image quality is good, the printed and non-printed areas have strong gloss, the dye fixability is good, the bleeding is small, the printing density is high, and the surface is high. An ink jet image receptor having high strength, low stickiness, good storability, a very photographic ink jet image receptor and a highly transparent OHP sheet was obtained.

Claims (5)

[Claims] 1. An ink jet image receptor having an ink image receiving layer provided on at least one surface of a support, wherein the ink image receiving layer contains at least gelatin, and the surface of the ink image receiving layer has a contact angle to a 20 wt% glycerin aqueous solution. An image receptor for inkjet, which is 80 degrees or less. 2. An ink-jet image receptor having an ink image-receiving layer on at least one surface of a support, the ink image-receiving layer containing at least gelatin, and the gelatin component is dried without being gelled. An ink jet image receptor having an image receiving layer. 3. The image receptor for ink jet according to claim 1, wherein the ink image receiving layer contains a hardener. 4. The polyester film or resin-coated paper having a 60 degree gloss of 40 or more according to JIS-Z-8741 specular gloss measurement method, wherein the support is a polyester film or a resin coated paper. Image receiver for inkjet. 5. An ink image-receiving layer coating liquid containing at least gelatin is coated on a support at a temperature higher than the gelling temperature of the coating liquid, and then heated to a temperature higher than the gelling temperature in a fluid state of the coating liquid. A method for producing an ink jet image receptor, which comprises drying and drying to form an ink image receiving layer.