JP2005144997A - Inkjet recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording medium which shows the occurrence of no swell on the surface in a high-density recording part when the medium is used under a full color inkjet recording process, especially a photoinkjet recording process consuming a large amount of ink; and enables a sharp image equal to a silver salt photography to be formed on account of sufficient ink absorption. <P>SOLUTION: In this inkjet recording medium with a substrate and at least not less than two ink acceptance layers formed on the substrate, the ink acceptance layer formed adjacent to the substrate among the ink acceptance layers, is a solvent absorbing layer. This solvent absorbing layer has one kind of an inorganic pigment with a particle whose size is not less than 1 μm and a particle whose size is less than 1 μm; and a water-soluble polymer binding agent. In addition, the ratio of the particle measuring not less than 1 μm in size and the particle measuring less than 1 μm in size of the inorganic pigment is 0.1≤(the particle measuring not less than 1μm in size)/(the particle measuring less than 1 μm in size)≤0.4 in terms of a volume ratio obtained by a light scattering diffraction particle size measurement. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  INDUSTRIAL APPLICABILITY The present invention is suitable for forming a print (printed material) having a texture or image quality as a silver salt photograph by a method of applying a recording droplet such as ink to a recording medium, particularly an ink jet recording method. The present invention relates to various recording media.

  The ink jet recording method is a method for recording images, characters, and the like by causing micro droplets of a recording liquid (recording liquid) such as ink to fly by various operating principles and adhere to a recording medium such as paper. High speed, low noise, easy multi-coloring, large recording pattern flexibility, no need for development, and other features such as deployment to printers, copiers, word processors, facsimiles, plotters, etc. The development of the output unit in the information equipment is further performed and is rapidly spreading. In recent years, high-performance digital cameras, digital videos, scanners, etc. are being offered at low cost, and coupled with the widespread use of personal computers, printers that employ inkjet recording methods for the output of image information obtained from them are extremely suitable. It has come to be used. In such a background, it has been required to easily output an image that is inferior to that of silver salt photography or plate-making multicolor printing by an inkjet recording method.

  In order to meet these requirements, improvements have been made to the structure and recording method of the printer itself, such as higher recording speed, higher definition, and full color, and improvements to the structure and characteristics of the recording medium have been actively studied. ing.

  Various types of recording media used for inkjet recording and the like have been proposed. For example, Patent Document 1 discloses a recording medium in which a layer having a void mainly composed of a silica pigment having a large specific surface area as a main component is provided as an ink receiving layer in order to improve the ink absorption speed. Discloses a recording medium in which the voids of the pigment layer forming the ink receiving layer are adjusted. Patent Documents 3 and 4 describe that an amorphous silica powder is blended in order to increase ink absorbability by an ink receiving layer and obtain a print dot having a high print density and no ink bleeding.

  In recent years, alumina hydrate has been attracting attention as a constituent material for the portion of the recording medium that receives ink. This is because alumina hydrate is a fine particle having a positive charge, so that the fixing property of the dye in the ink is good and a transparent layer can be formed, so that the coloring property is high and the water resistance is excellent. This is because it has features such as the ability to obtain images. Examples of the recording medium using such alumina hydrate include recording media described in Patent Documents 5 to 7. Patent Documents 8 and 9 disclose a recording medium having an ink receiving layer made of alumina hydrate particles having a specific crystal thickness or pore structure. Patent Document 10 discloses a recording medium having an ink receiving layer mainly composed of aggregated particles of alumina hydrate on a paper substrate such as fine paper in addition to the plastic film.

  Alumina hydrate is generally obtained by hydrolysis of aluminum alkoxide or hydrolysis of sodium aluminate as described in Patent Documents 11 and 12, and sodium aluminate described in Patent Document 13 or the like. It can manufacture by well-known methods, such as the method of adding and neutralizing aqueous solutions, such as aluminum sulfate and aluminum chloride, to aqueous solution.

  Non-Patent Document 1 reports that the porous structure of alumina hydrate is affected by the precipitation temperature, solution pH, aging time, and surfactant. In addition, it is generally known that pseudoboehmite in alumina hydrate has a cilia shape and a non-cilia shape as described in Non-Patent Document 2.

For example, in Patent Document 14, the ink receiving layer having one or more ink-receiving layers on a support and a cationic polymer dye fixing agent contained in the layer below the outermost layer allows the ink to be removed due to moisture after printing. By adding at least two or more kinds of cationic polymers in a porous ink absorbing layer composed of a hydrophilic binder and inorganic fine particles provided on a non-absorbing support in Patent Document 15 in a recording medium that suppresses bleeding, Each of the recording media has improved ink bleeding and bronzing under high humidity.
JP-A-52-9074 JP-A-63-22997 JP-A-55-51583 JP-A-56-157 Japanese Patent Laid-Open No. 7-232473 Japanese Patent Laid-Open No. 9-66664 JP-A-2-276670 JP-A-9-99627 Japanese Patent Laid-Open No. 11-286171 JP-A-10-95754 US Pat. No. 4,242,271 US Pat. No. 4,202,870 Japanese Patent Publication No.57-44605 Japanese Patent No. 3204749 JP 2001-39026 A Rocek et al., “Collect czech Chem Commun”, 1991, 56, p. 1253-1262 Rosek et al., "Applied catalysis", 1991, 74, p. 29-36

  In such a recording medium, high ink absorption performance is required for high-speed printing of a printer in recent years, and various methods are currently proposed to achieve them without reducing high image density. For example, a structure having many voids for absorbing and holding ink using a pigment having a large pore volume is formed in the ink receiving layer, or an ink absorbing polymer material is used for forming the ink receiving layer. Although attempts have been made, dots may become clouded inside the ink receiving layer due to irregular reflection of light, and on the contrary, desired image density and glossiness may not be obtained. In addition, in order to increase the ink absorbency, it is often necessary to increase the coating thickness of the ink receiving layer, and in that case, it is necessary to take a costly method for both the material and the manufacturing process. It is.

  In some cases, the ink absorbability is insufficient. In this case, in order to obtain sufficient ink absorbency, it is necessary to form a thick ink receiving layer on the ink absorbable layer. In addition, there are cases where the glossiness after printing is lowered, the color stability after printing, and the printing part is swollen due to the swelling of the paper base material.

  Further, when the printed matter is handled under high temperature and high humidity after printing, there may be a problem that the dye in the recording medium is moved by moisture in the atmosphere. When a cationic polymer is contained in the ink receiving layer, it is possible to suppress ink bleeding due to moisture after printing. In this case, the cationic polymer affects the light stability of the dye, and the image is preserved in the environment. In some cases, the performance may be reduced. An object of the present invention is to provide a recording medium having an extremely high print image density and high ink absorbency at a low cost, and recording that does not cause ink bleeding without impairing the light stability of the image even under high temperature and high humidity. To provide a medium.

The recording medium of the present invention that can achieve the above object is an inkjet recording medium in which a substrate and at least two or more ink-receiving layers are formed on the substrate,
Of the ink receiving layer, a layer provided adjacent to the substrate has one kind of inorganic pigment having particles of 1 μm or more and particles of less than 1 μm and a water-soluble polymer binder, The ratio of the particles of 1 μm or more and the particles of less than 1 μm in the pigment is 0.1 ≦ (particles of 1 μm or more) / (particles of less than 1 μm) ≦ 0.4 in the volume ratio obtained by light scattering diffraction particle size distribution measurement. The present invention relates to an inkjet recording medium which is an absorption layer.

In the present invention, it is further preferable that the pore volume having a pore radius of 50 mm or less measured by the nitrogen adsorption / desorption method of the solvent absorption layer is 0.2 ml / g or less.
In the present invention, it is further preferable that the substrate is a fibrous substrate.
In the present invention, it is further preferable that the inorganic pigment is an aluminum pigment.
In the invention, it is preferable that the layer formed on the solvent absorbing layer of the ink receiving layer is a dye fixing layer mainly composed of an aluminum pigment.

  The recording medium of the present invention has sufficient ink absorptivity without the occurrence of surface waviness in a high density recording portion when used in a full color ink jet recording system, particularly a photo ink jet recording system with a large amount of ink. It is possible to form a clear image comparable to a silver salt photograph.

  In addition, according to the present invention, the above object can be achieved even if the thickness of the ink receiving layer is thin, and therefore it is possible to efficiently produce a recording sheet.

  The ink jet recording medium of the present invention has a solvent absorption layer containing one kind of inorganic pigment, and the volume ratio of the inorganic pigment obtained by light scattering diffraction particle size distribution measurement is 0.1 ≦ (1 μm or more inorganic). Pigment particles) / (inorganic pigment particles of less than 1 μm) ≦ 0.4. As a result, it is possible to provide a recording medium with an extremely high print image density and fast ink absorptivity, which does not deteriorate glossiness due to paper swelling after printing, at a low cost. At the same time, it is possible to provide a recording medium in which ink bleeding does not occur without impairing the light stability of the image even under high temperature and high humidity.

  Furthermore, since an extremely high image density can be obtained in image formation on a recording medium, an image having a texture and image quality as a silver salt photograph can be obtained. In addition, by selecting an input system such as a digital camera and using an inkjet recording system as an output, it has high definition and high quality, and has the texture and image quality of silver halide photography, or exceeds that. It is possible to provide a print having an image with a process that is simpler and faster than a silver salt photograph.

  The above-described effects in the present invention are considered to be due to the following actions. In the present invention, in the process in which the recording liquid adhering to the outermost surface of the dye fixing layer permeates into the inside of the recording medium, the dye is adsorbed on the outermost dye fixing layer, and the solvent is separated and permeates the lower layer. The solvent absorption layer is formed between the fibrous base material and the outermost layer and has a function of receiving the permeated solvent.

  In this process, the particle diameter of the solvent absorption layer is controlled to 0.1 ≦ (particles of 1 μm or more) / (particles of less than 1 μm) ≦ 0.4 by the volume ratio obtained by light scattering diffraction particle size distribution measurement. In addition, it is possible to secure a sufficient amount of particles having a high absorption performance of less than 1 μm to absorb the solvent, and the solvent can be quickly transferred to the solvent absorption layer, and the ink resulting from the solvent can be stored even under high temperature and high humidity. A sufficient amount to prevent the paper from swelling when absorbing particles with a particle size of 1 μm or more, which has the effect of preventing paper swelling and prevents the paper from swelling, It has been found that it is possible to prevent drooling. When the volume ratio of (particles of 1 μm or more) / (particles of less than 1 μm) is less than 0.1, the proportion of particles of 1 μm or more to prevent twisting is too small, and the paper substrate swells when printed When the volume ratio of (particles of 1 μm or more) / (particles of less than 1 μm) exceeds 0.4, the proportion of particles of less than 1 μm decreases, and the absorption performance Is not sufficiently exhibited, it is difficult to sufficiently suppress ink bleeding under high temperature and high humidity, and the ratio of particles of 1 μm or more is increased, which may affect the smoothness of the recording medium. In addition, at this time, it has been found that by using one kind of inorganic pigment for the solvent absorption layer, the printed portion can be prevented from being swayed due to the swelling of the paper substrate. It is not clear why such an effect is exhibited when one kind of inorganic pigment is used. However, when two or more kinds of inorganic pigments are mixed, the degree of moisture absorption of each inorganic pigment is probably different. Because of the difference, it is assumed that the behavior of each inorganic pigment in the layer with respect to moisture is different.

  The present inventor studied the configuration for imparting high ink absorption performance at a low cost without causing deterioration of the glossiness of the printed portion due to the swelling of the paper. Swelling of paper after printing is suppressed and ink absorption performance is improved by including a pigment component with a small change due to moisture absorption with a large particle size that has an effect of suppressing ink and a pigment component with small particle size with high ink absorption performance I found out that I can. This also makes it possible to reduce the thickness of the ink receiving layer formed thereon, thereby reducing costs and ensuring productivity.

  Moreover, since the smoothness of the surface of the fibrous base material is further improved by using the above pigment, the smoothness of the dye fixing layer to be formed can be improved and a higher glossiness can be obtained. Furthermore, by suppressing the swelling of the base material, the treatment effect is further improved, particularly when used in combination with a rewetting type casting method.

  In this way, by using specific pigments, while maintaining higher absorbency, it suppresses cockling and expresses high glossiness, and further suppresses ink bleeding without impairing the light stability of the image even at high temperatures and high humidity. An effect is obtained.

Examples of the substrate used in the recording medium of the present invention include fibrous substrates mainly composed of wood pulp and filler, such as appropriately sized paper and non-size paper. In order to impart texture such as silver salt photographs as fibrous substrate is preferably basis weight 120 g / m ² or more, more 150~180g / m ^2, a Stockigt sizing degree 100 seconds or more, more preferably 200 A thing more than a second is good. By using such a fibrous substrate, it is possible to provide a high-quality recording medium, for example, in the size of about A4 plate or A3 plate.

  In the present invention, as the pigment used in the solvent absorption layer, one kind of inorganic pigment having a particle diameter of 1 μm or more and a particle of less than 1 μm is used. As the average particle diameter of the pigment, those having an average particle diameter effective for increasing the smoothness, glossiness and solvent absorbability of the layer surface are desirable.

  As the particle diameter of the pigment, those having an average particle diameter in the range of 0.2 to 2 μm, more preferably in the range of 0.5 to 1 μm can be used. When it is in the above range, sufficient surface smoothness can be obtained, sufficient ink absorptivity can be obtained, and sufficient effects can be obtained in terms of image density and gloss after printing.

  A white pigment can be used as the inorganic pigment. Examples of white pigments include silica, kaolin, clay, barium sulfate, calcium carbonate, and aluminum pigments. However, the ratio of the particles of 1 μm or more and the particles of less than 1 μm is 0.1 ≦ (particles of 1 μm or more) / (particles of less than 1 μm) ≦ 0.4 in the volume ratio obtained by light scattering diffraction particle size distribution measurement. There are no particular restrictions. It is preferable that 0.1 ≦ (particles of 1 μm or more) / (particles of less than 1 μm) ≦ 0.3, and 0.2 ≦ (particles of 1 μm or more) / (particles of less than 1 μm) ≦ 0.3. It is more preferable. By having (particles of 1 μm or more) / (particles of less than 1 μm) within these ranges, a recording medium having an extremely high print image density and excellent fast ink absorbability can be obtained. Of these, aluminum pigments are particularly preferable. Specific examples include alumina hydrate and γ-type crystal alumina particles. These particles are particularly preferable from the viewpoint of ink absorbability and suppression of waviness of the recording portion.

  As a method of adjusting the inorganic pigment within the above range, an inorganic pigment having (particles of 1 μm or more) / (particles of less than 1 μm) in a range exceeding 0.4 is desired by a ball mill disperser or an ultrasonic disperser. It is preferable to perform pulverization so as to be in the range of the particle size distribution. In addition, the inorganic pigment particles having a particle size of (1 μm or more) / (particles of less than 1 μm) of less than 0.1 are fired to sinter (particles of 1 μm or more) / (particles of less than 1 μm) to 0.4 or more. Then, it is preferable to perform a pulverization treatment with a ball mill disperser or an ultrasonic disperser so that a desired particle size distribution is obtained. Conditions for performing ball mill treatment or ultrasonic dispersion treatment are particularly limited if the particle size distribution of the pulverized inorganic pigment is 0.1 ≦ (particles of 1 μm or more) / (particles of less than 1 μm) ≦ 0.4. It is preferable to determine the processing conditions while measuring the particle size distribution so that the particle size distribution is 0.1 ≦ (particles of 1 μm or more) / (particles of less than 1 μm) ≦ 0.4. In addition, when the inorganic pigment particles having (particles of 1 μm or more) / (particles of less than 1 μm) of less than 0.1 are calcined, it is preferably calcined at 500 ° C. for 1 hour or more.

  As a binder for binding these inorganic pigments, any water-soluble polymer having a binding ability (water-soluble polymer binder) can be used without particular limitation as long as the effects of the present invention are not impaired. Examples of such binders include synthesis of polyvinyl alcohol, vinyl acetate, oxidized starch, etherified starch, casein, gelatin, soy protein, styrene-butadiene latex, polyvinyl acetate, polyacrylate, polyester, polyurethane and the like. Polymers can be raised. These binders can be used alone or in combination. The blending ratio of the pigment and the binder in the solvent absorption layer can be preferably selected from the range of 100: 8 to 100: 25, and the upper limit is 100: 15, and the lower limit is more preferably 100: 10. .

  The solvent-absorbing layer is obtained by applying a coating liquid obtained by adding and dispersing a pigment in a suitable solvent such as water together with a binder, if necessary, on the surface on which the fibrous substrate layer is to be formed. It can be formed by drying.

The coating amount of the solvent absorbing layer is preferably in the range of 5 to 40 g / m ² in order to sufficiently absorb the ink solvent component and to provide the necessary smoothness. Coating and drying methods are not particularly limited.

  In addition, this coating liquid further includes a dispersant, a thickener, a pH adjuster, a lubricant, a fluidity modifier, a surfactant, an antifoaming agent, a water-resistant agent, a release agent, and a fluorescent whitening agent. In addition, an ultraviolet absorber, an antioxidant and the like can be added within a range not impairing the effects of the present invention. Further, the pores of the solvent absorption layer preferably have a pore volume with a pore radius of 50 mm or less of 0.20 ml / g or less, more preferably 0.10 ml / g or less, and 0.05 ml / g. More preferably, it is g or less. When the pore volume is within these ranges, the solvent is rapidly moved to the solvent absorption layer, and ink bleeding can be suppressed.

On the other hand, as a material used for forming the ink receiving layer (dye fixing layer) provided on the solvent absorption layer, for example,
1) The ink absorption speed is fast and there is no more than necessary bleeding.
2) High print density and color developability,
3) Any material can be used as long as it satisfies desired characteristics such as excellent weather resistance and can form a coating layer having surface glossiness.

  Among these, aluminum pigments are preferable. As one of them, an alumina hydrate represented by the following general formula can be mentioned as a preferable one.

式中、ｎは１、２または３の整数のいずれかを表し、ｍは０〜１０、好ましくは０〜５の値を表す。但し、ｍとｎは同時に０にはならない。ｍＨ₂Ｏは、多くの場合、ｍＨ₂Ｏ結晶格子の形成に関与しない脱離可能な水相をも表すものである為、ｍは整数または整数でない値を取ることもできる。またこの種の材料を加熱するとｍは０の値に達することがありうる。

In the formula, n represents an integer of 1, 2 or 3, and m represents a value of 0 to 10, preferably 0 to 5. However, m and n are not 0 at the same time. Since mH ₂ O often represents a detachable aqueous phase that does not participate in the formation of the mH ₂ O crystal lattice, m can take an integer or non-integer value. Also, when this type of material is heated, m can reach a value of zero.

  In addition, the alumina hydrate provides the necessary properties such as transparency, gloss, and fixability of colorants in recording liquids such as dyes as described above, and cracks when forming the ink receiving layer. Those having good coating properties are preferred. From such a point of view, those manufactured by the above-mentioned known methods and alumina hydrates selected from commercially available products can be used as constituent materials of the ink receiving layer as alumina-containing pigments.

  Moreover, an aluminum oxide can be mention | raise | lifted as another preferable aluminum-type pigment. As this aluminum oxide, what is usually called a Bayer method, the thing manufactured by baking the aluminum hydroxide obtained by carrying out the hot caustic soda processing of the bauxite which is a natural mineral can be used. In addition to this, those produced by spark discharge of metal aluminum pellets in water and then calcining the obtained aluminum hydroxide, methods of decomposing inorganic aluminum salts (alum etc.), etc. can be used.

  As for the crystal structure of aluminum oxide, it is known that the transition from kibsite-type and boehmite-type aluminum hydroxide to γ, σ, η, θ, α-type aluminum oxides depends on the heat treatment temperature. Yes. Of course, any of these production methods and crystal structures can be used in the present invention. The dye fixing layer may contain one or more of the above contents.

The aluminum pigment such as aluminum oxide or alumina hydrate used in the dye fixing layer of the present invention preferably has a BET specific surface area of 100 to 160 m ² / g. That is, when the specific surface area of the aluminum-based pigment is 160 m ² / g or less, it can have good ink absorbency depending on the particle size of the pigment. Further, when the density is 100 m ² / g or more, the color density does not decrease due to light scattering. The average particle size of the aluminum pigment used in the dye fixing layer of the present invention is preferably 0.10 μm or more and 1.0 μm or less. When the average particle diameter is 0.10 μm or more, good ink absorbability can be obtained, and when it is 1.0 μm or less, the glossiness does not decrease.

  The physical properties of the aluminum pigment used in the dye fixing layer are preferably an average particle size of 0.10 μm or more and 1.0 μm or less. Further, (particles of 1 μm or more) / (particles of less than 1 μm) <0.1. More preferably, the average particle size is 0.10 μm or more, 0.5 μm or less, (particles of 1 μm or more) / (particles of less than 1 μm) <0.05. When the average particle size exceeds 1.0 μm, or (particles of 1 μm or more) / (particles of less than 1 μm) is 0.1 or more, the surface gloss of the recording medium decreases, and when printing is performed In addition, the printed portion is not preferable because it tends to be white and cloudy.

  When adjusting to such a particle size distribution range and average particle size, coarse particles (1 μm or more) that are not suitable as a dye fixing layer can be almost removed, so that the pigment dispersion can be centrifuged. preferable. The conditions for the centrifugal treatment are not particularly limited as long as the particle size distribution of the inorganic pigment is (particles of 1 μm or more) / (particles of less than 1 μm) <0.1, and the particle size distribution is (particles of 1 μm or more) / (1 μm It is preferable to determine the processing conditions while carrying out the particle size distribution measurement so that <less than particles) <0.1.

  Therefore, as a preferable combination of the aluminum pigment used for the dye fixing layer and the solvent absorbing layer, the particle size distribution range of the aluminum pigment used for the dye fixing layer is (particles of 1 μm or more) / (particles of less than 1 μm) <0.1. And the average particle size is 0.10 μm or more and 1.0 μm or less, and the particle size distribution range of the aluminum pigment used in the solvent absorption layer is 0.1 ≦ (particles of 1 μm or more) / (particles of less than 1 μm). ≦ 0.4, and the average particle size is 0.20 μm or more and 2.0 μm or less. As a more preferable combination, the particle size distribution range of the aluminum pigment used in the dye fixing layer is (particles of 1 μm or more) / (particles of less than 1 μm) <0.05, and the average particle size is 0.10 μm or more, 0 The particle size distribution range of the aluminum pigment used for the solvent absorption layer is 0.1 ≦ (particles of 1 μm or more) / (particles of less than 1 μm) ≦ 0.4, and the average particle size is 0.50 μm. This is 2.0 μm or less. When combined with these, the effect of suppressing ink bleeding without increasing the high-absorbency, suppressing cockling and developing a high glossiness, and without impairing the light stability of the image even at high temperatures and high humidity. Is remarkably obtained.

  In forming the dye fixing layer in the recording medium of the present invention, a binder can be used as necessary. A water-soluble polymer can be mentioned as a suitable binder which can be used in combination with an aluminum pigment. For example, polyvinyl alcohol or a modified product thereof, starch or a modified product thereof, gelatin or a modified product thereof, casein or a modified product thereof, gum arabic, cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, SBR latex, NBR latex, Conjugated diene copolymer latex such as methyl methacrylate-butadiene copolymer, functional group-modified polymer latex, vinyl copolymer latex such as ethylene vinyl acetate copolymer, polyvinyl pyrrolidone, maleic anhydride or copolymer thereof Examples thereof include a polymer and an acrylate copolymer. These binders can be used alone or in combination.

  The mixing ratio of the aluminum pigment and the binder can be arbitrarily selected from the range of 5: 1 to 15: 1, preferably by weight. By setting the amount of the binder within the above range, the mechanical strength of the ink receiving layer can be further increased, cracking and powder falling off during the formation of the ink receiving layer can be prevented, and a more suitable pore volume can be maintained. It becomes possible. The dye fixing layer may be composed of two or more layers.

  On the other hand, the coating liquid for forming the dye fixing layer includes a dispersant, a thickener, a pH adjuster, a lubricant, a fluidity modifier, a surfactant, an antifoaming agent, and a water resistant agent as necessary. It is also possible to add a release agent, a fluorescent brightening agent, an ultraviolet absorber, an antioxidant and the like within a range not impairing the effects of the present invention.

  In the recording medium of the present invention, as a method for forming the dye fixing layer, a method of applying and drying the dispersion solution containing the above-mentioned alumina hydrate on a substrate using a coating apparatus can be used. The coating method is not particularly limited, and commonly used coating techniques such as blade coater, air knife coater, roll coater, curtain coater, bar coater, gravure coater, die coater, spray device, etc. can be used. .

The coating amount of the coating liquid at the time of forming the dye fixing layer is related to the coating amount of the light reflecting layer, but the fixability of the colorant component in the recording liquid such as the dye and the smoothness of the dye fixing layer. the to be more favorable, preferably 40 g / m ² or less on a dry solid basis, 20 to 40 g / m ² is more preferable. If necessary, after the ink receiving layer is formed, a baking treatment can be performed. When the dry solid content is 20 g / m ² or more, the ink absorbability does not decrease even when combined with the solvent absorbing layer. Further, the dye fixing effect is sufficient, and the dye can be fixed on the dye fixing layer to obtain a sufficient color developability.

  Furthermore, it is preferable to perform a smoothing process such as a cast process after forming the dye fixing layer. As a method for casting, there are a direct method, a gelation method, and a rewet method. Among these, the direct method is a method in which the surface of the layer is pressed against a heated mirror drum and dried, while the coating layer applied on the substrate at the time of forming the coating layer is still wet. In the gelation method, the coating layer on the substrate is still in a wet state when the coating layer is formed. It is pressure-bonded to the mirror drum and dried. Furthermore, in the rewet method, after forming the coating layer, it is again treated with hot water to return it to a wet state, and the surface of this coating layer is pressed against a heated mirror drum and dried. By these methods, it is possible to obtain high gloss on the surface of the coating layer. However, when a dense substrate is used to obtain a recording medium comparable to the texture of the silver salt photograph provided in the present invention, a rewetting method can be preferably used as the gloss treatment. This is because, when a wet coating layer is dried by pressure bonding to a mirror drum, in the case of a dense substrate, the evaporation of moisture from the back surface is extremely limited.

As the ink used when forming an image on the recording medium of the present invention, a conventionally known water-based ink can be used. In the present invention, it is particularly preferable to use an ink containing an anionic compound such as a water-soluble dye having an anionic group. Examples of the water-soluble dye used in this case include water-soluble direct dyes having an anionic group such as a sulfone group and a carboxyl group, acidic dyes, and reactive dyes. Such water-soluble dyes are generally used in a ratio of about 0.1 to 20% by mass in conventional inks, and this ratio may be the same in the present invention. The solvent used in the water-based ink used in the present invention is preferably water or a mixed solvent of water and a water-soluble organic solvent, and particularly preferable is a mixed solvent of water and a water-soluble organic solvent. As a water-soluble organic solvent, polyhydric alcohol having an effect of preventing ink drying is contained.

  As an ink jet recording method that can be used when forming an image by ink jet recording, a method using a piezoelectric element, a method using a heating element, or the like can be used without any particular limitation.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated concretely, this invention is not limited to these specific examples.

  The following (aluminum pigments A and B) were prepared as aluminum pigments used in the dye fixing layer provided on the solvent absorption layer.

(Production example)
Aluminum pigment A
Aluminum octoxide was synthesized by the method described in Patent Documents 11 and 12, and then hydrolyzed to produce an alumina slurry. Water was added to the alumina slurry until the solid content of the alumina hydrate became 5% by mass. Next, after raising the temperature to 80 ° C. and carrying out an aging reaction for 10 hours, spray drying was performed to form particles. For spray drying, GB22 manufactured by Yamato Scientific Co., Ltd. was used, and the apparatus conditions were changed to Inlet temp. It dried as 176 degreeC, ATOMIZING AIR 0.15 Mpa, PULSE JET 20, PUMP 4, and ASPIRATOR 10. After mixing these particles with pure water, adjusting the pH to 4 with hydrochloric acid and stirring for a while, components having a small particle size (0.01 μm or less) are removed by ultrafiltration, and after desalting, acetic acid is added. And peptized. Particles obtained by drying the colloidal sol after the peptization treatment were measured by X-ray diffraction and found to be pseudoboehmite.

  The aluminum pigment A was adjusted as described above. The average particle diameter determined by light scattering diffraction particle size distribution measurement of the aluminum pigment A is 0.12 μm, and the ratio of particles of 1 μm or more to particles less than 1 μm is 1 μm in volume ratio determined by light scattering diffraction particle size distribution measurement. The above particle / particle less than 1 μm = 0.02.

  For light scattering diffraction particle size distribution measurement, a light scattering diffraction type particle size distribution measuring device LS230 equipped with a Small Volume Module (manufactured by COULTER) was used. As a measurement sample, first, pigment particles 1 were dispersed in pure water using acetic acid as a dispersant to obtain a 20 mass% dispersion. Thereafter, 1 ml of the pigment particle 1 dispersion was added to 50 ml of pure water with a few drops of 10% by mass acetic acid, and the sample was stirred and measured (samples of other pigments (1 μm or more)). Particles) / (particles less than 1 μm) were also measured in the same manner).

Aluminum pigment B
Using the particles after spray drying of the above method, this was baked in an oven at 500 ° C. for 2 hours. The particles were measured by X-ray diffraction and found to be γ-type crystal alumina. The obtained particles were dispersed in pure water at a concentration of 20% by mass using acetic acid as a dispersant. Then, after processing for 60 minutes with an ultrasonic disperser, coarse particles (1.0 μm or more) were removed by centrifugation, and aluminum pigment B was prepared. Ultrasonic dispersion was performed using BONSON's SONFIER 450, with an output control of 6 and a duty cycle of 50%. In addition, for the centrifugal separation treatment, HIMAC center SCR7B manufactured by Hitachi, Ltd. was used, and the treatment was performed at a rotational speed of 4000 rpm and a treatment time of 15 minutes, and the supernatant component was collected. The average particle diameter obtained by light scattering diffraction particle size distribution measurement of the aluminum pigment B is 0.20 μm, and the ratio of particles of 1 μm or more to particles less than 1 μm is 1 μm in volume ratio obtained by light scattering diffraction particle size distribution measurement. The number of particles / particles less than 1 μm = 0.0.

  The following were used as pigments used in the solvent absorption layer.

Pigment particle 1
Using the particles after spray drying by the above method, this was baked in an oven at 500 ° C. for 1 hour. The particles were measured by X-ray diffraction and found to be γ-type crystal alumina. The obtained particles were dispersed in pure water at a concentration of 20% by mass using acetic acid as a dispersant. After that, wet pulverization was performed for 15 hours by a ball mill pulverizer to obtain pigment particles 1. For ball milling, processing was performed at a rotational speed of 100 rpm using a ball mill rotating base and an alumina pot, 5 mm diameter alumina balls manufactured by Asahi Rika Seisakusho. The ratio of the particles of 1 μm or more to the particles of less than 1 μm in the pigment particle 1 was (particles of 1 μm or more) / (particles of less than 1 μm) = 0.13 in a volume ratio obtained by light scattering diffraction particle size distribution measurement.

Pigment particle 2
Using the particles after spray drying by the above method, this was baked in an oven at 500 ° C. for 2 hours. The particles were measured by X-ray diffraction and found to be γ-type crystal alumina. The obtained particles were dispersed in pure water at a concentration of 20% by mass using acetic acid as a dispersant. Then, what was processed for 60 minutes by the ultrasonic disperser was used as the pigment particle 2. Ultrasonic dispersion was performed using BONSON's SONFIER 450, with an output control of 6 and a duty cycle of 50%. The ratio of the particles of 1 μm or more to the particles of less than 1 μm was 1 μm or more / 1. The light scattering diffraction particle size distribution was measured in the same manner as for the pigment particle 1.

(Example 1)
A coating layer was formed as follows on a fibrous substrate having a basis weight of 150 g / m ² and a Steecht size of 200 seconds.

Pigment particles 1 were dispersed in pure water using acetic acid as a dispersant to obtain a 20 mass% dispersion. Next, polyvinyl alcohol PVA117 (trade name: manufactured by Kuraray Co., Ltd.) was dissolved in pure water to obtain a 9% by mass solution. For the solvent absorption layer formation, the pigment particle 1 dispersion and the polyvinyl alcohol solution are mixed and stirred so that the solid content of the pigment particle 1 dispersion and the solid content of the polyvinyl alcohol solution are 100: 10 by weight. It was set as the coating liquid. This coating solution was applied on the above base material so as to have a dry weight of 10 g / m ² to form a solvent absorption layer. The pore volume with a pore radius of 50 mm or less measured by the nitrogen adsorption / desorption method of this coating layer was 0.004 ml / g. For the measurement by the nitrogen adsorption / desorption method, a gas adsorption / desorption analyzer Omnisoap 360 (manufactured by COULTER) was used. In the test method, a sheet-like sample was cut into an appropriate size, and the pore radius was measured by a continuous volume method using nitrogen gas for a sample which had been vacuum degassed at 100 ° C. for 8 hours. From the obtained measurement results, a pore volume of 50 mm or less of the solvent absorption layer was calculated (pore radius measurement was performed in the same manner in other examples and comparative examples).

  Next, the colloidal sol of the aluminum pigment A was concentrated to obtain a 17 mass% dispersion. The dispersion and the polyvinyl alcohol solution were mixed and stirred so that the solid content of the aluminum pigment A and the solid content of the polyvinyl alcohol was 100: 10 by weight to obtain a coating solution for forming a dye fixing layer. .

On the coating layer (solvent absorption layer), a dye fixing layer forming coating solution was applied by die coating to form a dye fixing layer having a dry thickness of 35 g / m ² .

  The surface of the coated dye fixing layer was subjected to a rewet cast treatment using hot water (80 ° C.) using a rewet cast coater to obtain the recording medium 1 of the present invention.

(Example 2)
A coating solution for forming a solvent absorption layer was prepared in the same manner as in Example 1 except that the pigment particle 2 was used. Using this coating solution, a coating layer (solvent absorption layer) was formed on the same fibrous substrate as in Example 1 so that the dry weight was 15 g / m ² . Further, the pore volume of the coating layer (solvent absorption layer) measured in the same manner as in Example 1 and having a pore radius of 50 mm or less measured by the nitrogen adsorption / desorption method was 0.024 ml / g. A dye fixing layer is formed in the same manner as in Example 1 except that the aluminum pigment B is used in place of the aluminum pigment A and the coating thickness is set to 30 g / m ² by dry weight. Recording medium 2 was obtained.

(Example 3)
A solvent absorption layer was formed in the same manner as in Example 1 except that the solid content of the pigment particle 1 dispersion and the solid content of the polyvinyl alcohol solution were 100: 15 by weight and the dry weight was 20 g / m ² . Further, the pore volume of the solvent absorption layer having a pore radius of 50 mm or less, measured by the same nitrogen adsorption / desorption method as in Example 1, was 0.003 ml / g. Further, a dye fixing layer was formed in the same manner as in Example 1 except that the aluminum pigment B was used in place of the aluminum pigment A and the coating thickness was 25 g / m ² by dry weight, and the same casting treatment was performed. A recording medium 3 of the present invention was obtained.

Example 4
A solvent absorption layer was formed in the same manner as in Example 2 except that the solid content of the pigment particle 2 dispersion and the solid content of the polyvinyl alcohol solution were 100: 25 by weight and the dry weight was 25 g / m ² . Further, the pore volume of the solvent absorption layer having a pore radius of 50 mm or less as measured by the same nitrogen adsorption / desorption method as in Example 1 was 0.031 ml / g. A dye fixing layer is formed in the same manner as in Example 2 except that the aluminum pigment A is used in place of the aluminum pigment B, and the coating thickness is 20 g / m ² by dry weight. Recording medium 4 was obtained.

(Comparative Example 1)
Instead of the pigment particles 1 used in the solvent absorption layer, precipitated calcium carbonate particles dispersed in pure water so as to have a solid content concentration of 20% by mass were used. The ratio of particles of 1 μm or more to particles of less than 1 μm in the precipitated calcium carbonate was 1 μm or more / particles of less than 1 μm = 0.45 in a volume ratio obtained by light scattering diffraction particle size distribution measurement. A recording medium 5 for Comparative Example 1 was obtained in the same manner as Example 1 except that the pigment particles were changed.

(Comparative Example 2)
Instead of pigment particles 2, aluminum pigment B before ultrasonic treatment (the ratio of particles of 1 μm or more to particles of less than 1 μm is a particle ratio of 1 μm or more / less than 1 μm by volume ratio determined by light scattering diffraction particle size distribution measurement) The recording medium 6 for Comparative Example 2 was obtained in the same manner as in Example 2, except that the following particles were used.

(Example 5)
Instead of pigment particles 1, the alumina hydrate particles were dispersed in pure water so as to have a solid content concentration of 20% by mass, and 2% of acetic acid as a dispersant was added to the mass of the alumina hydrate particles. . The ratio of the particles of 1 μm or more to the particles of less than 1 μm in the alumina hydrate particles was 1 μm or more / particles of less than 1 μm = 0.29 in a volume ratio determined by light scattering diffraction particle size distribution measurement. A recording medium 7 of the present invention was obtained in the same manner as in Example 1 except that the pigment was changed. Further, the pore volume measured by the nitrogen adsorption / desorption method of the solvent absorption layer, which was measured in the same manner as in Example 1, was 0.21 ml / g.

(Comparative Example 3)
On the fibrous substrate used in Example 1, two dye-containing layers were not formed on the fibrous base material, and only the dye fixing layer was dried at a coating amount of 30 g / m ² using the aluminum-based pigment A. And a casting process similar to that of Example 1 was performed to obtain a comparative recording medium 8.

(Comparative Example 4)
The particles obtained by spray drying the aluminum pigment A were baked in an oven at 500 ° C. for 1 hour. The particles were measured by X-ray diffraction and found to be γ-type crystal alumina. The obtained particles were dispersed in pure water at a concentration of 20% by mass using acetic acid as a dispersant. Thereafter, wet pulverization was performed with a ball mill pulverizer for 25 hours to obtain pigment particles 3. The ratio of the particles of 1 μm or more to the particles of less than 1 μm in the pigment particle 3 was (particles of 1 μm or more) / (particles of less than 1 μm) = 0.06 in a volume ratio obtained by light scattering diffraction particle size distribution measurement. A recording medium was produced in the same manner as in Example 1 except that this pigment particle 3 was used in place of the pigment particle 1, and a comparative recording medium 9 was obtained.
According to the following method, recording media 1 to 9 were evaluated, and the results are shown in Table 1.

  Images were formed using a photo printer (trade name: BJ F870 manufactured by Canon Inc.) using an inkjet method, and ink absorbency, waviness of the printed portion, and bleeding of the printed portion after storage under high temperature and humidity were evaluated. For the images, several types of photographic images were prepared, printed using the highest image quality mode of the above-mentioned apparatus, and comprehensively evaluated from the obtained images. The evaluation was made by paying attention to the composite black portion, leaf green color, and sky blue portion in the image. The evaluation method for each evaluation item is shown below.

(Ink absorption)
The presence or absence of beading was judged and evaluated visually.
A: No occurrence even in composite black with the largest amount of ink B: Appears in composite black but not in green or sky blue C: Other than A and B above.

(Waviness of printing part)
The presence or absence was visually judged and evaluated.
A: No occurrence even in composite black with the largest amount of ink B: Appears in composite black but not in green or sky blue C: Other than A and B above.

(Ink bleeding)
The ink bleeding after storage under high temperature and high humidity was also evaluated by visually judging the presence or absence. The storage conditions are a temperature of 30 ° C., a humidity of 80%, and a storage period of 168 hours.
A: No occurrence even in composite black with the largest amount of ink B: Appears in composite black but not in green or sky blue C: Other than A and B above.

表１の結果より実施例１〜４の記録媒体ではインク吸収性、うねり及び高温高湿下保存後のインクの滲みが全てＡで良好であった。また、実施例５の記録媒体はうねりがＡでインク吸収性及びインクの滲みがＢであったが、実用には十分耐えるものであった。一方、比較例１の記録媒体ではインク吸収性、うねり及び高温高湿下保存後のインクの滲みが全てＢであり、比較例２及び３の記録媒体では評価項目がＢ又はＣであった。また、比較例４ではインク吸収性、高温多湿下保存後のインクのにじみはＡであったが、うねりがＣであった。このため、比較例１〜４の記録媒体では実用に耐えるものではなかった。

From the results shown in Table 1, all of the recording media of Examples 1 to 4 had good ink absorption, waviness, and ink bleeding after storage under high temperature and high humidity. Further, the recording medium of Example 5 had a swell of A and an ink absorbability and an ink bleeding of B, but was sufficiently durable for practical use. On the other hand, in the recording medium of Comparative Example 1, ink absorption, swell, and ink bleeding after storage under high temperature and high humidity were all B, and in the recording media of Comparative Examples 2 and 3, the evaluation items were B or C. In Comparative Example 4, the ink absorbability and the ink smear after storage under high temperature and high humidity were A, but the swell was C. For this reason, the recording media of Comparative Examples 1 to 4 were not practical.

Claims (5)

An inkjet recording medium in which a substrate and at least two or more ink-receiving layers are formed on the substrate,
Of the ink receiving layer, a layer provided adjacent to the substrate has one kind of inorganic pigment having particles of 1 μm or more and particles of less than 1 μm and a water-soluble polymer binder, The ratio of the particles of 1 μm or more and the particles of less than 1 μm in the pigment is 0.1 ≦ (particles of 1 μm or more) / (particles of less than 1 μm) ≦ 0.4 in the volume ratio obtained by light scattering diffraction particle size distribution measurement. An ink jet recording medium comprising an absorbing layer.   2. The ink jet recording medium according to claim 1, wherein the pore volume having a pore radius of 50 mm or less measured by a nitrogen adsorption / desorption method of the solvent absorption layer is 0.2 ml / g or less.   The inkjet recording medium according to claim 1, wherein the substrate is a fibrous substrate.   The inkjet recording medium according to claim 1, wherein the inorganic pigment is an aluminum pigment.   The inkjet recording medium according to any one of claims 1 to 4, wherein the layer formed on the solvent absorbing layer of the ink receiving layer is a dye fixing layer mainly composed of an aluminum pigment.