JPH11115308A - Recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the recording sheet having a colorant accepting layer, which can obtain an image sheet through ink jet recording, thermal transfer recording or electrophotographic recording and at the application and drying of which no crack develops and which can easily be formed. SOLUTION: In a recording sheet, in which a colorant accepting layer is provided on a support, the colorant accepting layer is formed by applying a coating fluid including fine inorganic particles and a water-soluble resin onto the support. By giving a solution including a crosslinker, which can crosslink the water-soluble resin simultaneously with the coating the coating fluid or during a period, in which a coated layer shows a constant rate drying speed, (or before the arrival of a falling rate drying speed), through a method such as coating or the like to the coated layer for hardening in order to the recording sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording sheet for recording using a color material. In particular, the present invention relates to a recording sheet that is advantageously used for forming an image sheet by ink jet recording, thermal transfer recording, electrophotographic recording, or the like.

[0002]

2. Description of the Related Art In recent years, with the rapid development of the information industry, various information processing systems have been developed, and recording methods and apparatuses suitable for each information system have been developed and adopted. Among such recording methods, in ink recording using an ink jet or a plotter, and in thermal transfer recording using a melting type color material or a sublimation type color material, a device used is reduced in weight and size, and noise is reduced. And excellent in operability and maintainability. Further, the apparatus used in such a recording method has been widely used recently because of easy colorization. In the conventional electrophotographic system, colorization is progressing, and high-resolution full-color printers and copiers have been developed and commercialized.

Various ink-jet systems have been developed. The physical methods are roughly divided into a method using a dye solution containing a water-soluble dye (aqueous ink) and a method using a dye solution containing an oil-soluble dye (oil-based ink). And a method of hot-melting a low-melting solid wax (wax ink) containing a dye. The mainstream is a type using an aqueous ink. In any case, this is a method of forming an image by discharging liquid fine droplets on the surface of the ink recording sheet.

The thermal transfer system is roughly classified into two types. The first method is a method of obtaining an image by transferring a heat-fusible ink applied on a support to a recording sheet by applying heat from the support and melting the ink in a heat-applied pattern ( In the second method, heat is applied from the support side to the heat-sensitive recording material comprising a resin having a high softening point and a sublimable dye on the support in the same manner as the former, and the heat-applied pattern is used. Is a method (sublimation thermal transfer) in which an image is obtained by transferring a sublimation dye to a recording sheet by sublimating the dye. The mainstream of the electrophotographic method is a method in which an electrostatic latent image is formed by giving an optical image pattern to a charged photoconductive layer, then transferred to a recording sheet after developing the toner, and the toner is fused and fixed by heat.

On the other hand, in the following applications, it is necessary to use a transparent sheet. In many cases, an image is formed and recorded as described above using a transparent film having a color material receiving (absorbing) layer on the surface. Create a sheet. For example, OHP films, which are increasingly used in place of slides in meetings, etc., backlight display films, which are increasingly used in place of printed posters and display boards, and second original drawing films, etc. Can be mentioned.

[0006] The transparent film on which an image is formed by the above-described recording method has the following characteristics:
The color material must be firmly adhered to the surface of the recording sheet.In the case of ink jet recording, liquid ink should be absorbed quickly and no ink bleeding or ink accumulation should be obtained in order to obtain a fine image. Etc. are required.

[0007] In order to solve these problems, various proposals have hitherto been made. For example, JP-A-57-1
JP-A-4091 and JP-A-61-19389 propose a recording sheet comprising a transparent support and a transparent layer of colloidal silica and a water-soluble resin provided thereon. However, in this transparent layer, the colloidal silica particles are too large and the amount of the water-soluble resin is too large, so that a sufficiently large porosity cannot be obtained. Therefore, the recording sheet shows a sufficiently large ink absorption rate. There is a problem that it is difficult.

Further, JP-A-2-276670 and JP-A-3-281383 disclose a recording sheet provided with a coloring material receiving layer having pores formed of pseudo-boehmite fine particles. . According to the study by the present inventor, it has been found that although the recording sheet has improved ink absorbency, a sufficiently high transparency cannot be obtained because the refractive index is as high as 1.65.

Japanese Patent Application Laid-Open No. Sho 61-53598 discloses a support having thereon a transparent layer comprising synthetic silica, fine particles having a refractive index of 1.44 to 1.55, and a water-soluble resin. A recording sheet having the same is disclosed. Synthetic silica usually has a primary particle size exceeding 10 nm, and the secondary particles have a particle size of several hundred nm. Such secondary particles tend to scatter light, and thus a recording sheet containing such particles does not exhibit a sufficiently high light transmittance.
Further, since the transparent layer has relatively large pores due to the large secondary particles, it is not possible to sufficiently prevent the occurrence of ink bleeding and ink accumulation.

As a recording sheet that has solved the above-mentioned problems,
JP-A-7-276789 proposes a recording sheet in which a color material receiving layer having a high porosity three-dimensional structure formed of inorganic fine particles and a water-soluble resin is provided on a transparent support. . According to this configuration, the ink absorbency and the suppression of color mixture bleeding are sufficient, and an image with high resolution can be obtained.

[0011]

The high porosity colorant receiving layer formed from inorganic fine particles and a water-soluble resin generally has small particles and a large particle content. When applying a coating solution containing a material for forming such a color material receiving layer, according to the study of the present inventor, cracks may occur while the coating layer is dried. It became clear. And it became clear that this crack is particularly likely to occur when drying at a relatively high temperature in order to shorten the drying time. As a method for preventing this cracking, Japanese Patent Application Laid-Open No. 9-109545 proposes a method of making the viscosity of a binder of a coating liquid relatively high. However, this method is liable to cause uneven coating and the like. It is not preferable because it leads to a decrease in the properties. Further, this method is not sufficient in the effect of preventing cracks.

The inventors of the present invention have studied to prevent the above-mentioned color material receiving layer from cracking. As a result, the coating layer was found to have a crack after applying a coating material for forming a color material receiving layer on a support.
It has been clarified that this occurs during the drying, that is, at the time of transition from constant rate drying to reduced rate drying. Based on this knowledge,
The present inventor has further studied and found that it is possible to prevent cracks by increasing the film strength of the coating layer as soon as possible in the constant-rate drying state before the reduced-rate drying state starts. Reached.

Accordingly, the present invention provides a color material receiving layer which can obtain an image sheet by ink jet recording, thermal transfer recording or electrophotographic recording, does not easily generate cracks upon coating and drying, and can be easily formed. It is an object to provide a recording sheet having the same.

In particular, according to the present invention, the liquid ink is rapidly absorbed, and there is no unevenness in the absorption of the ink, a fine image free of ink bleeding or ink accumulation can be obtained, and cracks occur at the time of coating and drying. An object of the present invention is to provide a recording sheet having a color material receiving layer which can be easily formed without being used, and which is suitable for inkjet recording.

[0015]

According to the present invention, there is provided a recording sheet having a color material receiving layer provided on a support, wherein the color material receiving layer supports a coating solution containing inorganic fine particles and a water-soluble resin. A solution containing a cross-linking agent capable of cross-linking the water-soluble resin is applied and cured at the same time as the application or before the applied layer exhibits a reduced drying rate. The recording sheet is a layer obtained by the above method.

Preferred embodiments of the recording sheet of the present invention are as follows. (1) The crosslinking agent is boric acid or borate. (2) The inorganic fine particles are silica fine particles having an average primary particle diameter of 20 nm or less (preferably 10 nm or less, particularly in the range of 3 to 10 nm). (3) The water-soluble resin is polyvinyl alcohol or gelatin. (4) The weight ratio of the inorganic fine particles to the water-soluble resin is 1.5: 1 to 1
It is in the range of 10: 1. (5) The color material receiving layer has a porosity of 40 to 80% (particularly 50 to 80%).
80% porosity).

(6) The color material receiving layer contains a silane coupling agent having a basic group (particularly a quaternary ammonium base). (7) The coating material containing the inorganic fine particles and a water-soluble resin. When simultaneously applying the solution of the crosslinking agent and the solution of the crosslinking agent, simultaneously apply a solution that does not react with the crosslinking agent so that the layer of the solution is interposed between the layer of the coating solution and the layer of the solution of the crosslinking agent. And
This is a layer obtained by curing. (8) The recording sheet is for ink jet recording.

(9) The coating amount of the solution containing the crosslinking agent on the colorant receiving layer is in the range of 0.01 to 10 g / m ² (in the range of 0.05 to 5 g / m ² ) in terms of the crosslinking agent. (10) The colorant receiving layer has a three-dimensional network structure. (11) The colorant receiving layer has a haze of 30% or less. (12) The above-mentioned recording sheet for ink jet recording, wherein the layer thickness of the colorant receiving layer is 10 to 50 μm. (13) The above-mentioned recording sheet for electrophotography or thermal recording wherein the layer thickness of the colorant receiving layer is 0.1 to 10 μm.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The recording sheet of the present invention has a basic structure comprising a support and a colorant receiving layer formed on the support, and can be produced, for example, as follows. .

As a material that can be used as the support, a transparent material such as plastic or an opaque material such as paper may be used. In the invention, in order to utilize the transparency of the colorant receiving layer, the support is preferably a transparent support or a high gloss opaque support. As a material that can be used as the transparent support, a material that is transparent and has a property of withstanding radiant heat when used in an OHP or a backlight display is preferable. Such materials include:
Polyesters such as polyethylene terephthalate; nitrocellulose, cellulose acetate, cellulose esters such as cellulose acetate butyrate, and polysulfone, polyphenylene oxide, polyimide,
Examples thereof include polycarbonate and polyamide. Among these, polyesters are preferred, and polyethylene phthalate is particularly preferred. The thickness of the transparent support is
There is no particular limitation, but those having a size of 50 to 200 μm are preferred because they are easy to handle.

The high gloss opaque support preferably has a surface on the side on which the colorant receiving layer is provided having a glossiness of 40% or more. The glossiness is in accordance with JIS P-8142
This is a value obtained by measuring according to the method described in (Test Method for Specular Gloss at 75 ° of Paper and Paperboard). Examples of high gloss opaque supports include high gloss paper such as art paper, coated paper, cast coated paper, and baryta paper used for silver halide photographic supports; polyesters such as polyethylene terephthalate (PET); , Nitrocellulose, cellulose acetate and cellulose esters such as cellulose acetate butyrate, or polysulfone, polyphenylene oxide, polyimide, polycarbonate, plastic films such as polyamide,
This film is made opaque by adding a white pigment or the like to the film to make it opaque (by subjecting it to surface calendering, etc.)
Alternatively, there may be mentioned a film in which a polyolefin coating layer containing or not containing a white pigment is provided on the surface of the above-mentioned various papers, the above-mentioned transparent plastic film, or a plastic containing a white pigment or the like. Furthermore, a foamed polyester film containing a white pigment (eg, a calcium-containing foamed PET containing fine particles of polyolefin and forming voids by stretching) can also be mentioned.
A polyolefin-coated paper generally used as a silver salt photographic support (a type of a support provided with a polyolefin coating layer such as a paper support having a surface provided with a white pigment-containing polyolefin layer), or Special paper or the like provided with a metal deposition layer or the like can be suitably used. In particular, a paper support provided with a white pigment-containing polyolefin layer, a polyester (preferably PET) film provided with a white pigment-containing polyolefin layer, a white pigment-containing polyester film, or a white pigment-containing foamed polyester film is preferable. The thickness of the opaque support is
There is no particular limitation, but those having a size of 50 to 200 μm are preferred because they are easy to handle.

The support may be a corona discharge treatment, a flame treatment,
Those subjected to an ultraviolet irradiation treatment may be used.

The colorant-receiving layer of the present invention is formed such that, when a coating solution containing inorganic fine particles and a water-soluble resin is coated on a support, the coating layer exhibits a rate of drying at the same time as or at the same time as the coating. This is a layer in which a water-soluble resin obtained by applying a solution of a cross-linking agent onto the coating layer and curing the same before the coating is cured by the cross-linking agent.

Examples of the water-soluble resin include resins having a hydroxyl group as a hydrophilic structural unit, such as polyvinyl alcohol (PVA), and cellulose resins (methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), Carboxymethylcellulose (CMC), chitins, and starch; polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene glycol (PEG), and polyvinyl ether (PVE), which are resins having an ether bond; and an amide group or amide Polyacrylamide (PAAM) and polyvinylpyrrolidone (PVP), which are resins having a bond, can be given.
Further, a polyacrylate having a carboxyl group as a dissociable group, a maleic acid resin, an alginate and a gelatin; a polystyrene sulfonate having a sulfone group, an amino group, an imino group, a tertiary amine and a quaternary ammonium salt are used. Having polyallylamine (PAA), polyethyleneimine (PEI), epoxidized polyamide (EPA
m), polyvinyl pyridine and gelatins.

As the inorganic fine particles, for example, silica fine particles, colloidal silica, calcium silicate, zeolite,
Examples include kaolinite, halloysite, muscovite, talc, calcium carbonate, calcium sulfate, boehmite, pseudo-boehmite and the like. From the viewpoint of not lowering the transparency, those having a refractive index in the range of 1.40 to 1.60 are preferable. Among these, silica fine particles are preferred. The average primary particle diameter of the inorganic fine particles is generally 20 nm or less (preferably 10 nm or less, particularly 3 to 10 nm), and the refractive index is preferably around 1.45.

Since the silica particles are liable to adhere to each other due to hydrogen bonding due to silanol groups on the surface, a structure having a particularly high porosity can be formed when the average primary particle diameter is particularly 10 nm or less as described above, The ink absorption characteristics are improved. Silica particles are roughly classified into a wet method and a dry method according to the production method. In the wet method, the mainstream is a method in which active silica is generated by acid decomposition of a silicate, which is appropriately polymerized, coagulated and sedimented to obtain hydrous silica. On the other hand, dry silica is a method by high-temperature gas-phase hydrolysis of silicon halide (flame hydrolysis method), a method in which silica sand and coke are heated and reduced by an arc in an electric furnace and oxidized with air ( The method of obtaining anhydrous silica by the arc method is the mainstream. These hydrated silica and anhydrous silica have different properties in terms of the density of silanol groups on the surface, the presence or absence of vacancies, etc., and exhibit different properties, respectively. In the case of silicic anhydride (anhydrous silica), three-dimensional porosity is particularly high. This is preferable because the structure can be easily formed. Although the reason for this is not clear, the density of silanol groups on the surface of hydrated silica is as large as 5 to 8 particles / nm ^2, and the particles are likely to be densely aggregated (aggregate).
To three / nm ² and for small, coarse flocculation (flocculate) and porosity is estimated to be due to become high structure.

From the viewpoint of transparency, the type of the resin to be combined with the silica fine particles is important.
PVA, especially low saponification degree (preferably 70 to 90 saponification degree)
%) Of PVA is suitable in terms of light transmittance. PVA is
Although the structural unit has a hydroxyl group, the hydroxyl group and a silanol group on the surface of the silica particle form a hydrogen bond, thereby facilitating the formation of a three-dimensional network structure in which the secondary particle of the silica particle is a chain unit. It is thought that a colorant receiving layer having a structure with a high rate can be obtained. In the ink jet recording, the porous layer thus obtained not only absorbs ink rapidly by a capillary phenomenon and enables fine recording without ink bleeding or ink accumulation, but also a coloring material in thermal recording, and an electronic material. The toner in photographic recording can be firmly adhered. The reason is that the coloring material or the toner penetrates into the pores of the porous layer, and as a result, a shape anchor effect caused by the three-dimensional network structure occurs, thereby firmly fixing the coloring material or the like. It is. In addition, since the ratio of the inorganic fine particles is large, the heat resistance is high and the emboss resistance in electrophotographic recording is also high.

The ratio of the inorganic fine particles (preferably silica fine particles) to the water-soluble resin (PB ratio: the weight of the inorganic fine particles with respect to the weight of the water-soluble resin of 1) has a great influence on the film structure. As the PB ratio increases, the porosity, pore volume, and surface area (per unit weight) increase. When the ratio exceeds 10, there is no effect on the film strength and cracking during drying. When the ratio is less than 1.5, the voids are closed with the resin, the porosity decreases, and the ink absorption performance decreases. Therefore, the PB ratio is 1.
A range of 5 to 10 is preferred. In particular, when directly touching an image on a recording sheet by hand, such as an OHP film, it is necessary to obtain a sufficient film strength. The PB ratio is particularly preferably 5 or less, and in order to obtain high-speed ink absorption with an ink jet printer. The PB ratio is particularly preferably 2 or more.
The ratio is more preferably in the range of 2 to 5.

For example, when the average primary particle diameter as described above is 1
0 nm or less of anhydrous silica and a water-soluble resin having a PB ratio of 2 to 5
When completely dispersed in an aqueous solution and dried by application, a three-dimensional network structure having secondary particles of silica particles as a chain unit is formed, the average pore size is 30 nm or less, the porosity is 50% or more, and the pore specific volume. 0.5ml / g or more and specific surface area is 100
A light-transmitting porous film of m ² / g or more can be easily formed.

The colorant receiving layer of the present invention is a layer obtained by curing a layer (porous layer) containing the above-mentioned inorganic fine particles and a water-soluble resin as main components and further using a crosslinking agent. Moreover, in the present invention,
The application of the cross-linking agent is performed at the same time as the application of the coating liquid for forming a porous layer or before the coating liquid layer for forming a porous layer exhibits a reduced drying rate. By this operation, it is possible to prevent cracks generated while the coating layer of the coating liquid for forming a porous layer is being dried. That is, the applied crosslinking agent-containing solution penetrates into the coating layer at the same time as when the coating liquid for forming a porous layer is applied, or before the coating layer exhibits a reduced drying rate, and Reacts promptly with the water-soluble resin of the above, and polymerizes (cures) the water-soluble resin, thereby immediately and greatly improving the film strength of the coating layer. As a result, it is possible to prevent cracks generated when the coating layer of the coating liquid for forming a porous layer is dried.

Examples of the crosslinking agent used include boric acid and borates (eg, orthoborate, InBO ₃ , ScBO ₃ , YBO)
₃ , LaBO ₃ , Mg ₃ (BO ₃ ) ₂ , Co ₃ (BO ₃ ) ₂ , diborate (eg, Mg ₂ B ₂ O ₅ , Co ₂ B ₂ O ₅ ), metaborate (eg, LiBO ₂₎ , Ca (BO ₂ ) ₂ , NaBO ₂ ,
KBO ₂ ), tetraborate (eg, Na ₂ B ₄ O ₇ .10H ₂₎
O), five borate _{(e.g., KB 5 O 8 · 4H 2} O, Ca 2 B 6
_{O 11 · 7H 2 O, CsB} 5 O 5), glyoxal, melamine-formaldehyde (for example, methylol melamine, alkylated methylol melamine), methylol urea, resol resin, and polyisocyanate. Of these, boric acid or borate is preferred. It is preferable to use boric acid and borate in combination with polyvinyl alcohol as a water-soluble resin since a crosslinking reaction is promptly caused.

When gelatin is used as the water-soluble resin, the following compounds known as hardeners for gelatin can be used as crosslinking agents. Aldehyde compounds such as formaldehyde, glyoxal and glutaraldehyde; ketone compounds such as diacetyl and cyclopentanedione; bis (2-chloroethylurea) -2-
Active halogen compounds such as hydroxy-4,6-dichloro-1,3,5 triazine, 2,4-dichloro-6-S-triazine sodium salt; divinylsulfonic acid;
1,3-vinylsulfonyl-2-propanol, N,
N'-ethylenebis (vinylsulfonylacetamide),
Active vinyl compounds such as 1,3,5-triacryloyl-hexahydro-S-triazine; N-methylol compounds such as dimethylol urea and methylol dimethylhydantoin; isocyanate compounds such as 1,6-hexamethylene diisocyanate; Description 3017280
No. 2,983,611; Carboximide compounds described in US Pat. No. 3,100,704; Epoxy compounds such as glycerol triglycidyl ether; 1,6-hexamethylene-N, N Ethylene imino compounds such as' -bisethylene urea; halogenated carboxaldehyde compounds such as mucophenoxy cyclolic acid; dioxane compounds such as 2,3-dihydroxydioxane; chromium alum, potassium alum, zirconium sulfate; Chromium acetate and the like.
These can be used in combination of two or more.

The solution of the crosslinking agent is prepared by dissolving the crosslinking agent in water and / or an organic solvent. The concentration of the crosslinking agent solution is preferably 0.05 to 10% by weight, particularly 0.1 to 7% by weight.
% By weight. Water is generally used as a solvent for the crosslinking agent. As the organic solvent, those in which each material can be dissolved may be used. Examples thereof include alcohols such as methanol and isopropyl alcohol; ketones such as methyl ethyl ketone; esters such as ethyl acetate; aromatic solvents such as toluene; ethers such as tetrahydrofuran; Examples thereof include halogenated solvents such as dichloromethane.

In the present invention, when a coating liquid (coating liquid for forming a porous layer) containing inorganic fine particles and a water-soluble resin as main components is coated on a support, the coating layer is crosslinked so as not to cause cracking. An agent is applied to quickly improve the film strength of the coating layer. In practice, the crosslinking agent solution is applied simultaneously with the application of the coating liquid containing the inorganic fine particles and the soluble resin as the main component, or immediately after the coating liquid containing the inorganic fine particles and the water-soluble resin as the main component is applied. A crosslinker solution is applied.

Next, after applying a coating liquid (coating liquid for forming a porous layer) containing inorganic fine particles and a water-soluble resin as main components,
A method for quickly applying a crosslinking agent solution before the coating layer exhibits a reduced drying rate will be described. The coating liquid for forming a porous layer is prepared, for example, by adding silica fine particles having an average primary particle diameter of 10 nm or less to water (for example, 10 to 15% by weight), and using a high-speed rotating wet colloid mill (for example, CLEARMIX (M Technic) For example, using 1)
0000 rpm (preferably 5000 to 20000 rpm
m) for 20 minutes (preferably 10-3
After dispersing for 0 min), an aqueous polyvinyl alcohol solution (for example, PVA having a weight of about 1/3 of silica) is added, and the dispersion is further carried out under the same conditions as described above. The coating solution thus obtained is a uniform sol, and a porous layer having a three-dimensional network structure can be obtained by forming this on a support by the following coating method.

The coating liquid for forming a porous layer is applied, for example, by coating a coating liquid obtained by further adding an antistatic agent, a mordant and the like to the above-mentioned coating liquid, if desired, onto the support (film). Can be implemented. The coating can be performed by a known coating method such as an extrusion die coater, an air doctor coater, a bread coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, and a bar coater.

After the application of the coating solution for forming a porous layer, before the coating layer exhibits a reduced drying rate,
The solution containing the crosslinking agent of the present invention is applied in the same manner as the above-mentioned coating solution for forming a porous layer, and dried to obtain the cured color material receiving layer of the present invention. The crosslinking agent solution may be applied by a method such as spraying.

The time before the coated layer exhibits the reduced rate drying rate is usually several minutes from immediately after the coating, during which time the content of the solvent in the coated layer decreases in proportion to time. It shows the constant rate drying rate, which is a phenomenon that occurs. For the period showing such a constant rate drying rate, see the Chemical Engineering Handbook (70
7-712 pages, published by Maruzen Co., Ltd., October 2, 1980
5).

The colorant-receiving layer of the present invention is prepared by coating or spraying the above-mentioned solution containing a crosslinking agent while the coating layer shows a constant rate of drying after the application of the coating liquid for forming a porous layer. Is given. After the application of the coating liquid for forming a porous layer, drying is performed.
Generally, at 50 to 180 ° C. for 0.5 to 10 minutes (especially 0.
(5-5 minutes). This drying time naturally depends on the amount of application, but the above range is appropriate.

The coating layer of the coating solution for forming the porous layer is applied by dipping the support having the coating layer in a solution containing a cross-linking agent within a period in which the coating layer exhibits a constant drying rate. The cross-linking agent is introduced into the coating layer by spray coating the layer-containing solution with the cross-linking agent. The application of the crosslinking agent-containing coating solution, in addition to the above method, curtain flow coater, extrusion die coater, air doctor coater, bread coater, rod coater,
Known coating methods such as a knife coater, a squeeze coater, a reverse roll coater, and a bar coater can be used, but an extrusion die coater,
A method in which the coater does not directly contact the coating layer using a curtain flow coater, a bar coater, or the like is preferable.

The coating amount of the colorant receiving layer of the crosslinking agent-containing coating solution, the range of 0.01 to 10 g / m ² with a crosslinking agent terms are common, the range of 0.05-5 g / m ² preferable. After the application of the crosslinking agent-containing coating solution, the coating layer is generally 40 to 180
It is heated at a temperature of 0.5 to 30 minutes for drying and curing. It is preferable to heat at 40 to 150 ° C. for 1 to 20 minutes. For example, when using boric acid as a crosslinking agent, it is preferable to heat at 60 to 100 ° C. for 5 to 20 minutes.

Next, another method of forming the colorant receiving layer of the present invention is to simultaneously apply a coating liquid (coating liquid for forming a porous layer) containing inorganic fine particles and a water-soluble resin as main components, and simultaneously carry out a crosslinking agent solution. The method for applying the varnish will be described. The coating solution for forming a porous layer and the solution containing a cross-linking agent can be obtained by simultaneously applying and curing on a support such that the coating solution for forming a porous layer comes into contact with the support. The simultaneous application of the coating solution for forming a porous layer and the solution containing a crosslinking agent can be performed by, for example, a coating method using an extrusion die coater or a curtain flow coater. Drying after simultaneous coating (multilayer coating) is generally performed at 40 to 150 ° C. for 0.5 to
The coating is performed by heating for 10 minutes to cure the coating layer. Further, it is preferable to heat at 40 to 100 ° C. for 0.5 to 5 minutes. For example, when using boric acid as a crosslinking agent, it is preferable to heat at 60 to 100 ° C. for 5 to 20 minutes.

When the above-mentioned multilayer coating is carried out, for example, by an extrusion die coater, the two types of coating liquid form an overlay before being transferred onto the extrusion die coater, that is, before being transferred onto the support. And two coating layers (multilayer)
Since the cross-linking reaction has already occurred at the interface between the two layers when transferring to the support, viscosity increases due to mixing of the discharged coating liquid near the discharge port of the extrusion die coater, which hinders the coating operation. May be harmful. Therefore, when performing the above simultaneous coating, together with the application of the coating solution for forming a porous layer and the solution containing the crosslinking agent, a solution that does not react with the crosslinking agent is further placed between the coating solution layer and the solution layer. It is preferable to apply three layers simultaneously so as to intervene. Examples of the liquid that does not react with the cross-linking agent include an aqueous solution containing a trace amount of a water-soluble resin that does not react with the cross-linking agent (used as a thickener).

After coating and drying, the obtained color material receiving layer is passed through a roll nip under heat and pressure using, for example, a super calendar or a gloss calendar.
It is possible to improve surface smoothness, transparency and coating film strength. However, since such a process lowers the porosity (that is, the ink absorbency decreases), it is necessary to perform the treatment under a condition in which the porosity does not decrease much.

In the case of ink jet recording, the thickness of the obtained colorant receiving layer needs to have an absorption capacity to absorb all the droplets, which is determined in relation to the porosity of the coating film. There is a need. For example, if the ink amount is 8 nL / mm ² ,
If the porosity is 60%, a film having a thickness of about 15 μm or more is required. In the case of ink jet recording, 10 to 10
A film thickness in the range of 50 μm is preferred. In the case of thermal transfer or electrophotography, a thin film is sufficient because a colorant or toner is adsorbed on the surface, and a film thickness of 0.1 to 10 μm is preferable.

The inorganic fine particles and the water-soluble resin which mainly constitute the color material receiving layer may each be a single material or a mixture of a plurality of materials. The colorant receiving layer is mainly composed of the above-mentioned inorganic fine particles and a water-soluble resin, but may further contain various inorganic salts and an acid alkali as a pH adjuster in order to enhance the dispersibility of the particles. In addition, various surfactants may be used for the purpose of improving coating suitability and surface quality. Even if it contains surfactants with ionic conductivity or metal oxide fine particles with electronic conductivity to suppress triboelectric charging or exfoliation charging of the surface, or to adjust surface electrical resistance in electrophotography Good. Further, a mordant may be used for the purpose of fixing a dye and increasing water resistance in ink jet recording. Further, various matting agents may be included for the purpose of reducing the friction characteristics of the surface. Further, various antioxidants and ultraviolet absorbers may be included for the purpose of suppressing the deterioration of the coloring material.

Further, an undercoat layer may be provided between the colorant receiving layer and the support for the purpose of increasing the adhesiveness or adjusting the electric resistance. Further, the colorant receiving layer may be provided on one side of the support, or may be provided on both sides to suppress curling or the like. In the case of using OHP or the like, when the color material receiving layer is provided only on one side, an antireflection film may be provided on the opposite side or both sides to enhance light transmittance.

[0048]

【Example】

Example 1 (1) Composition of coating solution for forming porous layer (colorant receiving layer before cross-linking) (parts by weight indicating the blending amounts of all the following coating solutions are as follows:
All represent solid content or non-volatile content) Anhydrous silica fine particles (average primary particle diameter: 7 nm; 10 parts by weight surface silanol groups: 2-3 particles / nm ² ; refractive index: 1.45; Aerosil 300 (Nippon Aerosil Co., Ltd.) ))) Polyvinyl alcohol (degree of saponification: 81.8%; 3.3 parts by weight; degree of polymerization: 4000; PVA440 (manufactured by Kuraray Co., Ltd.)) ion-exchanged water 136.0 parts by weight of silica fine particles in ion-exchanged water ( 73.3 parts by weight), and using a high-speed rotating wet colloid mill (CLEARMIX (manufactured by M Technique Co., Ltd.)) to obtain 1
After dispersion at 0000 rpm for 20 minutes, an aqueous polyvinyl alcohol solution (dissolved in the remaining 62.7 parts by weight of ion-exchanged water) was added, and the mixture was further dispersed under the same conditions as above to form a porous layer. A coating solution was obtained.

The above coating solution was applied on the surface of a 200 μm-thick laminated paper for photographic printing paper at an application amount of 200 cc / m ² using an extrusion die coater, and was heated at 80 ° C. (wind speed 3 m / sec.) Using a hot air drier. ) For 3 minutes. The coating layer exhibited a constant rate drying rate during this period. After drying for 3 minutes, this coating layer was immediately immersed in a boric acid-containing solution of the following (2) for 1 second, and dried at 80 ° C. for 10 minutes. As a result, a color material receiving layer having a dry film thickness of 27 μm was formed.

(2) Boric acid-containing solution 1 part by weight of boric acid 0.2 part by weight of surfactant (F-144D, manufactured by Dainippon Ink and Chemicals, Inc.) 98.8 parts by weight of ion-exchanged water

(3) Composition of Silane Coupling Agent Solution Having Quaternary Ammonium Salt M-100C (manufactured by Sumitomo Chemical Co., Ltd.) 1.6 parts by weight p-toluenesulfonic acid (10% by weight methanol solution) 6 parts by weight Silane coupling agent (AZ-6160, manufactured by Nippon Unicar Co., Ltd.) 4.0 parts by weight Methanol 32.8 parts by weight The silane coupling agent solution was placed on the color material receiving layer in # 3.1. Coating with a coating amount (solid content) of 2.1 g / m ² using a bar coater, followed by heating at 80 ° C. for 5 minutes to receive a color material treated with a silane coupling agent having a quaternary ammonium salt A layer was formed. A recording sheet for ink jet was obtained as described above.

Example 2 The same procedure as in Example 1 was carried out except that the following coating solution was used as the coating solution for forming the porous layer (colorant receiving layer before cross-linking). By processing the ring agent, a recording sheet for ink jet was obtained. (1) The composition of the coating solution for forming the porous layer (colorant receiving layer before cross-linking) (the value of parts by weight indicating the blending amount of all the following coating solutions is
Dry silica fine particles (average primary particle diameter: 7 nm; 10 parts by weight, surface silanol groups: 2 to 3 particles / nm ² ; refractive index: 1.45; Aerosil 300 (Nippon Aerosil Co., Ltd.) ))) Polyvinyl alcohol (degree of saponification: 81.8%; 3.0 parts by weight; polymerization degree: 4000; PVA440 (manufactured by Kuraray Co., Ltd.)) 1.5 parts by weight of vinylpyrrolidone / dimethylaminoethyl methacrylate quaternary salt copolymer (Rubicut PQ11, manufactured by BSF Japan Co., Ltd.) 136.0 parts by weight of ion-exchanged water

The silica fine particles are added to ion-exchanged water (73.3 parts by weight), and a high-speed rotating wet colloid mill (CLEARMIX (M Technic Co., Ltd.)
)) And dispersed at 10,000 rpm for 20 minutes, and then a copolymer with a polyvinyl alcohol aqueous solution (dissolved in the remaining 62.7 parts by weight of ion-exchanged water) was added. Dispersion was performed under the same conditions, and then the pH was adjusted to 8 to 9 to obtain a coating solution for forming a porous layer.

Comparative Example 1 An ink jet recording sheet was prepared in the same manner as in Example 1, except that the boric acid-containing solution of (2) was not applied.

Comparative Example 2 An ink jet recording sheet was produced in the same manner as in Example 2 except that the boric acid-containing solution of (2) was not applied.

[Comparative Example 3] In Example 1, the drying for 3 minutes at 80 ° C. (air velocity 3 m / sec) was changed to the drying for 4 minutes at the same temperature using a hot air dryer (the coating layer was dried at a reduced rate during this period). A recording sheet for ink jet was prepared in the same manner except that the speed was shown).

The inkjet recording sheet obtained above was evaluated for inkjet suitability by the following measurement method. (1) Haze haze meter (HGM-2DP; Suga Test Instruments Co., Ltd.)
Was measured for parallel light transmittance to obtain haze. However, in each of Examples and Comparative Examples, the haze was measured using a recording sheet obtained by using a 100 μm-thick polyethylene terephthalate film instead of a laminated paper for photographic printing paper as a support.

(2) Porosity Mercury porosimeter (Pore Sizer 9320-PC2,
(Manufactured by Shimadzu Corporation) to obtain a distribution and calculate an average value. (3) Gloss Regarding the obtained recording sheet, JIS-P-8142
The gloss was measured according to the method described in (Test Method for Specular Gloss at 75 ° of Paper and Paperboard).

(4) Ink absorption speed Y is applied to the recording sheet by an ink jet printer (PM-700C; manufactured by Seiko Epson Corporation).
(Yellow), M (magenta), C (cyan), K (black), B
Solid printing of (blue), G (green) and R (red) was performed, and immediately thereafter (approximately 10 seconds later), the paper was contact-pressed, and the presence or absence of transfer of the ink to the paper was determined as follows. AA: No ink was transferred to paper. CC: Ink was transferred to paper. (5) Occurrence of Crack The obtained recording sheet was visually observed and evaluated as follows according to the presence or absence of the crack generated on the surface and the size thereof. AA: No crack is observed. BB: A crack having a length of 1 to 2 mm is observed. CC: A crack having a length of 3 mm or more is observed. The results of the above evaluation are shown in Table 1 below.

[0061]

[Table 1] Table 1 ──────────────────────────────────── Haze Porosity Gloss Ink Crack (%) (%) (%) Absorption rate ──────────────────────────────────── Example 1 13.3 62 53 AA AA Example 2 14.0 60 55 AA AA ──────────────────────────────────── Compare Example 1 16.0 61 53 AA BB Comparative Example 2 17.0 60 54 AA CC Comparative Example 3 13.8 62 53 AA BB ─────────────────────────── ─────────

[0062]

According to the recording sheet of the present invention, not only a liquid image can be rapidly absorbed in ink jet recording and a fine image free of ink bleeding or ink accumulation can be obtained, but also a color material which is a porous layer can be obtained. A high-quality image can be easily formed without causing cracks in the receiving layer. Further, since the recording sheet of the present invention is excellent in absorbency and prevention of bleeding, the adhesiveness of the coloring material or the toner is improved even in various recording methods such as thermal transfer recording and electrophotographic recording. Therefore, it can be said that the recording sheet of the present invention is a recording sheet suitable for various recording methods and excellent in productivity.

Claims (9)

[Claims] 1. A recording sheet comprising a support provided with a color material receiving layer, wherein the color material receiving layer is formed by applying a coating solution containing inorganic fine particles and a water-soluble resin onto the support. At the same time, or before the applied layer exhibits a reduced rate drying rate, it is a layer obtained by applying a solution containing a crosslinking agent capable of crosslinking the water-soluble resin and curing the solution. A recording sheet, characterized in that: 2. The recording sheet according to claim 1, wherein the crosslinking agent is boric acid or borate. 3. An inorganic fine particle having an average primary particle diameter of 20 n.
The recording sheet according to claim 1, wherein the recording sheet is a silica fine particle having a particle size of m or less. 4. The recording sheet according to claim 1, wherein the water-soluble resin is polyvinyl alcohol. 5. The weight ratio of the inorganic fine particles to the water-soluble resin is 1.
The recording sheet according to claim 1, wherein the recording sheet is in a range of 5: 1 to 10: 1. 6. The recording sheet according to claim 1, wherein the colorant receiving layer has a porosity of 40 to 80%. 7. The recording sheet according to claim 1, wherein the colorant receiving layer contains a silane coupling agent having a basic group. 8. When the colorant receiving layer simultaneously applies a coating solution containing inorganic fine particles and a water-soluble resin and a solution of the crosslinking agent, a solution that does not react with the crosslinking agent is further coated with a layer of the coating solution. The recording sheet according to any one of claims 1 to 7, wherein the recording sheet is a layer obtained by simultaneously applying and curing such a layer of the liquid between the and a layer of the solution of the crosslinking agent so as to be interposed therebetween. 9. The method according to claim 1, which is for inkjet recording.
9. The recording sheet according to any one of 8.