JP2008080605A - Medium to be recorded - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a medium to be recorded by which discoloring of images due to acid gas in the air during long period storing of the images and the blur of the images under high temperature and high humidity condition are effectively prevented. <P>SOLUTION: In the medium to be recorded, an ink accepting layer overlying a supporting body, in which at least one layer of resin layers having ink absorbing property and/or ink permeability, adjacently to a resin layer, are arranged on a base material contains a polymer compound obtained by at least reacting a sulfur containing compound having at least two active hydrogen groups and a compound having at least two isocyanate groups. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a recording medium suitable for recording with ink, and in particular, when applied to a printer or plotter using an ink jet recording method, has excellent ink absorbability, enables high-quality image recording, and images for long-term storage. The present invention relates to a recording medium in which color fading and image bleeding under high temperature and high humidity are suppressed.

  In the inkjet recording method, ink droplets adhere to a recording medium such as paper by various operating principles, and at the same time, the solvent component of the ink penetrates into the recording medium or evaporates, so that the color material component is covered. This is a recording method that deposits on a recording medium and records images, characters, and the like (hereinafter simply referred to as “images”). In addition, the ink jet recording system is characterized in that it has excellent high-speed printability, low noise, and flexibility in recording patterns, can easily perform multi-coloring, and does not require development and image fixing.

  In particular, an image formed by a multicolor ink jet method can obtain a recording that is inferior to an image by a multicolor printing by a plate making method or an image by a color photographic method. In recent years, it has rapidly spread as an image recording apparatus for various information devices because it has an advantage that the printing cost is lower than that of the printing technique and the photographic technique. For example, it is widely applied to fields that require full-color image recording, such as image design output in the design industry, production of color blocks in the printing field where photographic image quality is required, signboards and sample products that are frequently replaced. is there. Recently, personal computers and digital still cameras have become widespread, and there are many opportunities to output photographic images using an inkjet printer even in general households.

  However, the images recorded by inkjet printers are not suitable for long-term storage because they are remarkably discolored by acid gases and light in the atmosphere as compared to multicolor printing and color photographic images by the plate making system. is there. In particular, ozone gas contained in trace amounts in the atmosphere has a tendency to remarkably deteriorate recorded images, causing discoloration over time. Many proposals have been made so far to improve its performance. .

  For example, for the purpose of improving gas resistance, Patent Document 1 discloses a thioether compound, Patent Document 2 includes a hydrazide compound, Patent Document 3 and Patent Document 4 include a thiourea derivative, a thiosemicarbazide derivative, a thiocarbohydrazide derivative, and the like. There is disclosed a recording medium containing. In Patent Document 5, one kind from thiourea derivative, thiosemicarbazide derivative and thiocarbohydrazide derivative and one kind from iodine, iodide, dithiocarbamic acid, thiocyanate and thiocyanate are included. A recording medium is disclosed.

  However, in the conventional methods using these low molecular weight compounds, even water-insoluble compounds that are effective for discoloration cannot be added to water-based coating liquids. There is a detrimental effect of exacerbating image bleeding under high temperature and high humidity, and it is difficult to add an amount sufficient to improve the performance of the recording medium.

  Further, as a means for solving various problems in these low molecular weight compounds, a recording medium containing a high molecular compound having a discoloration or fading preventing effect incorporating a unit such as a sulfide group has been proposed. For example, Patent Document 6 discloses a recording medium containing a copolymer of a diallylamine compound and an ethylenically unsaturated compound having a sulfide group or a thiocarbonyl group. Patent Document 7 discloses an alkylthio group, an arylthio group, a thiocarbonyl group. And a recording medium containing a cationic polyurethane having any of thiocyanate groups. However, these high molecular compounds have a low discoloration / fading prevention effect with respect to the amount added compared to the low molecular weight compounds, and when applied to a recording medium having a void type ink receiving layer, the improvement effect is sufficiently high. When an amount that can be expressed is added, there is a problem that ink absorbability and image density are lowered.

  On the other hand, in glossy paper applications where photo-like high-quality recorded material can be obtained, glossy and photographic paper-like texture similar to silver halide photography is required, and recording using resin-coated paper as a support is required. The medium has become mainstream. However, the recording medium using the non-water-absorbent resin-coated paper has poor ink absorbability, and after image recording, the dye oozes when stored in a high-temperature and high-humidity environment for a long time, resulting in deterioration of image quality. Cause problems. As a method for solving such a problem, a cationic polymer is generally used. By adding the cationic polymer, bleeding of the dye is prevented, but a large amount of the cationic polymer is necessary to obtain a sufficient effect, and the amount of the cationic polymer in the ink receiving layer is relatively high. To increase. Therefore, in the porous (void type) ink receiving layer using the inorganic fine particles, there is a problem that the gap is reduced and the ink absorbability is lowered.

As a recording medium classified as glossy paper, there is a recording medium in which an ink receiving layer is formed by a casting method on a support having water absorbency such as paper or coated paper, other than those using the above resin coat. Such a recording medium has an advantage that it is excellent in ink absorbability and hardly causes bleeding of images in a high temperature and high humidity environment, compared with a recording medium using a non-absorbing support. However, a recording medium provided with an ink-receiving layer on a water-absorbing support is difficult to control curl, and when the gloss of the printed portion is reduced or the amount of applied ink is large, the recording medium There is a problem that cockling occurs. Furthermore, recording media manufactured by the casting method can achieve smoothness by bringing the ink receiving layer in a wet state into contact with a heated mirror roll in the manufacturing process. Since the rate is controlled and the productivity is lowered, it is disadvantageous in terms of cost compared to the case where a film or resin-coated paper that does not require such a smoothing treatment is used as a support.
Japanese Patent Laid-Open No. 01-115677 Japanese Patent Laid-Open No. 61-154989 Japanese Patent Publication No. 04-034953 Japanese Patent Laid-Open No. 07-314883 Japanese Patent Laid-Open No. 08-025796 JP 2003-089266 A JP 2004-345309 A

  The present invention has been made in view of the above-mentioned actual situation, and when recording with a printer or plotter using an ink jet recording method, high-quality image recording excellent in glossiness and ink absorbability is possible. Another object of the present invention is to provide a recording medium in which image discoloration due to acidic gas in the atmosphere during long-term image storage and image bleeding under high temperature and high humidity are effectively prevented.

  The inventors of the present invention can form an ink receiving layer having excellent glossiness without performing a smoothing process, and can record a high-quality image with excellent ink absorbability, and can record an image by an acid gas in the atmosphere. As a result of various studies to obtain a recording medium that effectively prevents discoloration and bleeding of images under high temperature and high humidity, a resin layer having ink absorbability and / or ink permeability is formed on a substrate. It has been found that the above problem can be solved by laminating an ink receiving layer containing a polymer compound obtained by reacting a sulfur-containing organic compound thereon, and has completed the present invention.

  That is, according to the present invention, in a recording medium in which an ink receiving layer is provided on at least one surface of a support, the support has at least one resin layer having ink absorptivity and / or permeability on a substrate. Provided is a recording medium comprising a layer and a polymer compound obtained by reacting a sulfur-containing organic compound in an ink receiving layer laminated on the resin layer.

In the recording medium according to the invention, the moisture permeability of the resin layer is 100 g / m ² · 24 hr or more; the smoothness of the support surface is 300 seconds or more; It is preferably a compound obtained by reacting at least a sulfur-containing organic compound having one or more active hydrogen groups with a polyisocyanate compound having two or more isocyanate groups; and the support has water absorption.

  With the above-described configuration of the present invention, high-quality image recording with excellent gloss and ink absorbability is possible, and further, color fading due to acid gas in the atmosphere and image bleeding under high temperature and high humidity It is possible to provide a recording medium in which the above is effectively prevented.

Next, the present invention will be described in more detail with reference to the best mode for carrying out the invention.
Although it does not specifically limit as a base material used in this invention, For example, the non-water-absorbing resin in which the one side or both surfaces of the paper in which moderate sizing was given, non-size paper, a coated paper, cast coated paper, a paper, etc. are polyolefin Made of paper such as resin-coated paper (hereinafter referred to as “resin-coated paper”) coated with: polyethylene, polypropylene, polyester, polylactic acid, polystyrene, polyacetate, polyvinyl chloride, cellulose acetate, polyethylene terephthalate, poly Transparent thermoplastic resin films such as methyl methacrylate and polycarbonate; sheet-like substances (such as synthetic paper) made of films made opaque by filling with inorganic substances or fine foaming; fabrics; and sheets made of glass or metal Can be mentioned.

  Among the above-mentioned substrates, from the viewpoint of ink absorbency, when the substrate itself also needs high liquid absorbency (particularly water-based ink or water-soluble solvent in water-based ink), A fabric or the like can be preferably used.

  In the present invention, a support is obtained by forming a resin layer on the substrate, but the smoothness of the support surface is increased, and the glossiness of the ink receiving layer formed on the resin layer is increased. In the case of producing a recording medium capable of imparting an image quality equivalent to that of a silver salt photograph, among the above-mentioned substrates having liquid absorbency, smoothness such as fine paper, coated paper, art paper, cast coated paper, etc. It is preferable to use a high substrate. In particular, JAPAN TAPPI paper pulp test method no. The Oken type smoothness according to 5 is preferably 10 seconds or more, more preferably 50 seconds or more, and still more preferably 100 seconds or more.

Although there is no restriction | limiting in particular in the thickness of a base material, The range of 25 micrometers-500 micrometers is preferable, More preferably, it is the range of 50 micrometers-300 micrometers. When the thickness of the base material is less than 25 μm, the recording medium to be obtained has a low rigidity, which causes inconveniences such as insufficient touch, texture or opacity when it is held. On the other hand, when the thickness is larger than 500 μm, the obtained recording medium becomes rigid, which may hinder the paper feeding traveling of the printer. There is not any special restriction on the weight of the substrate, it is preferably in the range approximate ^{25g / m 2 ~500g / m 2} .

  The support of the present invention absorbs and / or transmits ink (especially water-based ink or water-soluble solvent in water-based ink) on at least one surface of the substrate. It is obtained by forming a resin layer that is called “ink penetrability” as far as possible.

  The resin layer formed on the substrate is composed mainly of a hydrophilic polymer that has high wettability to water-based ink and can absorb and transmit water-based ink (especially water-soluble solvent in the ink). It is preferable. Examples of hydrophilic polymers include cellulose, cellulose derivatives [cellulose esters (cellulose acetate (cellulose diacetate, cellulose triacetate, etc.), cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose). Organic acid esters such as acetate phthalate; inorganic acid esters such as cellulose nitrate, cellulose sulfate and cellulose phosphate; mixed acid esters such as cellulose nitrate acetate), cellulose ethers (such as ethyl cellulose)], vinyl polymers [polyvinyl acetate and Fully or partially saponified products (such as polyvinyl alcohol), ethylene-vinyl acetate copolymer and fully or partially saponified products (ethylene-vinyl alcohol copolymer) )], Acrylic polymers [polyacrylonitrile, poly (meth) acrylic acid ester, polyacrylamide, poly N-methylacrylamide, etc.], polyvinylpyrrolidone, polyalkylene oxide (polyethylene glycol, etc.), polyalkyl vinyl ether (polymethyl vinyl ether, etc.) ), Carboxyl group-containing polymer or salt thereof (styrene-maleic anhydride copolymer, (meth) acrylic acid alkyl ester- (meth) acrylic acid copolymer, methyl vinyl ether-maleic anhydride copolymer, etc.), polysulfone Examples of the polymer include polysulfone and polyethersulfone, polyamide, and polyethyleneimine, and these hydrophilic polymers can be used alone or in combination of two or more.

  Among the hydrophilic polymers, cellulose, derivatives thereof; acrylic polymers such as polyacrylonitrile and (meth) acrylic acid esters; or polysulfone polymers that are used as materials for so-called semipermeable membranes, And vinyl polymers such as polyvinyl alcohol and ethylene-vinyl alcohol copolymer are particularly excellent in exhibiting the effect of the support of the present invention that suppresses bleeding of images under high temperature and high humidity, preferably Can be used.

  The hydrophilic polymer refers to those having a water contact angle of less than 80 °, but in the present invention, those having a contact angle of 60 ° or less are preferred from the viewpoint of improving the ink permeability of the resin layer. More preferred are those below. Here, the contact angle is an angle formed by the tangent to the water droplet and the polymer surface at the intersection of the surface of the water droplet placed on the polymer surface and the polymer. The smaller this angle, the better the wettability with water-based ink. Means high. The value of the contact angle in the present invention is such that the film made of the above hydrophilic polymer is allowed to stand at 23 ° C. and 50% RH for 12 hours, and then 2 μl of pure water is dropped on the film so that the liquid volume does not change (droplet Is not absorbed by the film and does not evaporate), and the angle at which the droplet spread becomes maximum (0.1 to 60 seconds after dropping) is determined by a contact angle meter (for example, an automatic contact angle meter CA-VP). (By Kyowa Interface Science Co., Ltd.)).

Further, in the present invention, in order to fully exhibit the effect of the support of the present invention that improves the ink permeability of the resin layer and suppresses the bleeding of the image under high temperature and high humidity, the JIS- The moisture permeability based on Z-0208 is preferably 100 g / m ² · 24 hr or more, and more preferably 300 g / m ² · 24 hr or more. The moisture permeability in the present invention is a value measured under temperature and humidity conditions (temperature: 40 ° C., humidity: 90% RH) defined in JIS-Z-0208.

  In the support of the present invention, the thickness of the resin layer formed on the substrate is preferably in the range of 10 to 100 μm, and more preferably in the range of about 10 to 50 μm. If the thickness of the resin layer is less than 10 μm, defects such as pinholes will occur during manufacturing, resulting in non-uniform ink absorbency, or unevenness on the substrate surface will not be alleviated, and the smoothness of the resin layer surface will be reduced. There is a case. On the contrary, when the thickness of the resin layer exceeds 100 μm, the ink absorbability may be lowered. In order to increase the glossiness of the ink receiving layer formed on the resin layer, the thickness of the resin layer is within the above range, and the surface roughness of the substrate [maximum height based on JIS-B-0601] (Ry)] is preferably larger.

  In the present invention, as a method for forming a resin layer on a substrate, the above-mentioned suitable hydrophilic polymer is appropriately selected, and a method in which these are dissolved or dispersed in an appropriate solvent and then applied; hydrophilic polymer And a method of laminating the film on a base material; a method of extruding and laminating the film on the base material, and the like. Examples of the coating method of the liquid in which the hydrophilic polymer is dissolved / dispersed include, for example, a roll coater method, a blade coater method, an air knife coater method, a gate roll coater method, a bar coater method, a size press method, a shim sizer method, and a spray coating method. , Gravure coating method, curtain coater method and the like. Examples of the adhesive used for laminating include epoxy, polyurethane, polyester, isocyanate, phenol, vinyl acetate, and acrylic.

  When cellulose is used as the hydrophilic polymer, viscose is coated and impregnated on the base material in the same manner as the viscose-processed paper manufacturing method similar to the conventionally known cellophane film manufacturing method. The resin layer may be formed by forming a cellulose film.

  Regarding the smoothness of the support surface on which the resin layer is formed on the substrate by the method as described above, the JAPAN TAPPI paper pulp test method no. The Oken smoothness according to 5 is 300 seconds or more, more preferably 500 seconds or more. When the smoothness of the support surface is less than 300 seconds, the glossiness of the surface of the recording medium and the formed image may be remarkably lowered.

  The resin layer may be transparent, semi-transparent, or opaque. However, if the ink receiving layer is transparent and the color of the substrate or the pattern of the uneven surface affects the printed image, the resin layer Various colorants, white pigments, fluorescent brighteners and the like may be added to the inside as long as the ink permeability of the resin layer is not hindered. The resin layer may be formed in multiple layers by changing the kind of hydrophilic polymer and the composition ratio of other additives, or can be formed on one side or both sides of the substrate. In particular, in the case of a support having a resin layer formed on both sides, even if an ink receiving layer is formed on one side, the resin layer itself has a low surface electrical resistance, so it is difficult to be charged. The applied antistatic treatment becomes unnecessary. In addition, the resin layer made of a hydrophilic polymer has a high affinity for the aqueous coating liquid used for forming the ink receiving layer, and the ink receiving layer is like a film having a hydrophobic surface or a resin-coated paper. There is also an advantage that it is not necessary to perform an easy adhesion treatment on the forming surface, and all of them work advantageously in reducing the manufacturing cost of the recording medium.

  The support having a resin layer formed only on one side of the substrate has adjustment of water resistance, curl balance, coefficient of friction with the surface of the ink receiving layer when stacked as a recording medium, and charging due to friction, or the like. For the purpose of preventing blocking, various types of resins other than the hydrophilic polymer used in the resin layer, or resins mixed with inorganic fine particles or antistatic agents, are coated on the back side where the resin layer is not formed. May be. Further, in order to improve the adhesive strength between the resin layer and the ink receiving layer formed thereon, the surface of the resin layer can be subjected to corona discharge treatment or various undercoat treatments.

  In the present invention, the recording medium of the present invention is obtained by forming an ink receiving layer containing a polymer compound obtained by reacting a sulfur-containing organic compound on the support.

  The polymer compound is a reaction product (hereinafter referred to as “polymer”) comprising a sulfur-containing organic compound (A) having two or more active hydrogen groups and a polyisocyanate compound (B) having two or more isocyanate groups as raw material components. Compound I ”), and in addition to the compound A and the compound B, an amine compound (C) having two or more active hydrogen groups is reacted, and at least a part of the amino group of the resulting polymer compound is A product cationized with an acid or a quaternizing agent (hereinafter referred to as “polymer compound II”).

  The compound A as a raw material component of the polymer compound I and the polymer compound II is not particularly limited, but a compound having at least one sulfide group in the molecule is preferable, and a particularly preferable range is that the number of sulfide groups is 1. Most preferred are compounds that are in the range of 1 to 10. Specific examples include compounds represented by the following general formulas (1) to (6). In addition, the following sulfur-containing organic compound A can be used alone or in combination of two or more thereof to synthesize polymer compound I and polymer compound II used in the present invention.

（式中ｎは１または２を表す。また、Ｒ¹はメチレン基、エチレン基、またはプロピレン基を表す。）

(In the formula, n represents 1 or 2. R ¹ represents a methylene group, an ethylene group, or a propylene group.)

（式中ｎは１または２を表す。また、Ｒ²およびＲ³はそれぞれ独立に水素原子、水酸基またはアルキル基を表し、Ｒ²およびＲ³は同一であっても異なっていてもよい。）

(In the formula, n represents 1 or 2. R ² and R ³ each independently represents a hydrogen atom, a hydroxyl group or an alkyl group, and R ² and R ³ may be the same or different.)

（式中ｎは０または１を表す。）

(Wherein n represents 0 or 1)

（式中ｎは１または２を表す。また、Ｒ⁴は硫黄原子または酸素原子を表し、Ｒ⁵は硫黄原子または−ＳＯ₂−を表し、Ｒ⁴およびＲ⁵は同一ではなく、それぞれ異なる基で構成される。）

(In the formula, n represents 1 or 2, R ⁴ represents a sulfur atom or an oxygen atom, R ⁵ represents a sulfur atom or —SO ₂ —, and R ⁴ and R ⁵ are not the same and are different groups. Composed of)

（式中Ｒ⁶およびＲ⁷はそれぞれ独立に水素原子またはアルキル基を表し、Ｒ⁶およびＲ⁷は同一であっても異なっていてもよい。）

(In the formula, R ⁶ and R ⁷ each independently represent a hydrogen atom or an alkyl group, and R ⁶ and R ⁷ may be the same or different.)

（式中Ｒ⁸は水酸基またはアルキル基を表す。）

(Wherein R ⁸ represents a hydroxyl group or an alkyl group.)

  Examples of the compound B that is a raw material component of the polymer compound I and the polymer compound II used in the present invention include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, and p-phenylene. Diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dichloro-4, 4'-biphenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, Limethylhexamethylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, hydrogenated xylylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexyl Although methane diisocyanate etc. are mentioned, it is not limited to these. Moreover, it is possible to synthesize the polymer compound I and the polymer compound II used in the present invention by using these polyisocyanate compounds alone or in combination of two or more.

  The polymer compound I used in the present invention is a reaction product of the compound A and the compound B. When the active hydrogen group is OH, for example, the compound A and the compound B are preferably reacted with each other at an equivalent ratio of OH / NCO of about 1. If the equivalent ratio of OH / NCO deviates significantly from 1, it is not preferable because the molecular weight of the obtained polymer compound I does not increase. A preferred OH / NCO equivalent ratio is in the range of 0.95 to 1.05. Further, in the reaction between the compound A and the compound B, a compound having two or more active hydrogen groups (hereinafter referred to as “compound D”) other than the compound A and the compound C described later may be used in combination. Although these compounds D will be described later, in this case as well, it is preferable to carry out the synthesis with an equivalent ratio of OH / NCO of all the reactants of around 1.

  Particularly preferred among the polymer compounds I used in the present invention obtained by the method as described above are compounds represented by the following general formulas (7) to (12).

（式中ｎは１または２を、Ｒ¹はメチレン基、エチレン基、またはプロピレン基を、Ｒ⁹はアルキレン、脂環を１つ以上含む二価の脂肪族炭化水素基もしくは芳香環を１つ以上含む二価の芳香族炭化水素基を表す。ｍは重量平均分子量が１，０００〜１５０，０００になる数である。）

(Wherein n is 1 or 2, R ¹ is a methylene group, ethylene group or propylene group, R ⁹ is alkylene, one divalent aliphatic hydrocarbon group containing one or more alicyclic rings or one aromatic ring. And represents a divalent aromatic hydrocarbon group including m.m is a number having a weight average molecular weight of 1,000 to 150,000.)

（式中ｎは１または２を、Ｒ²およびＲ³はそれぞれ独立で水素原子、水酸基またはアルキル基を、Ｒ²およびＲ³は同一であっても異なっていてもよい。なお、Ｒ⁹およびｍは一般式（７）と同義である。）

(A wherein n is 1 or 2, R ² and R ³ are independently a hydrogen atom, a hydroxyl group or an alkyl group, R ² and R ³ may be be the same or different. In addition, R ⁹ and m is synonymous with the general formula (7).)

（式中ｎは０または１を表す。Ｒ⁹およびｍは一般式（７）と同義である。）

(In the formula, n represents 0 or 1. R ⁹ and m are as defined in the general formula (7).)

（式中ｎは１または２を、Ｒ⁴は硫黄原子または酸素原子を、Ｒ⁵は硫黄原子または−ＳＯ₂−を表し、Ｒ⁴およびＲ⁵は同一ではなく、それぞれ異なる基で構成される。なお、Ｒ⁹およびｍは一般式（７）と同義である。）

(In the formula, n represents 1 or 2, R ⁴ represents a sulfur atom or an oxygen atom, R ⁵ represents a sulfur atom or —SO ₂ —, and R ⁴ and R ⁵ are not the same and are each composed of different groups. R ⁹ and m are as defined in general formula (7).)

（式中Ｒ⁶およびＲ⁷はそれぞれ独立で水素原子またはアルキル基を表し、Ｒ⁶およびＲ⁷は同一であっても異なっていてもよい。なお、Ｒ⁹およびｍは一般式（７）と同義である。）

(Wherein R ⁶ and R ⁷ each independently represent a hydrogen atom or an alkyl group, and R ⁶ and R ⁷ may be the same or different. R ⁹ and m are the same as those in formula (7)). Synonymous.)

（式中Ｒ⁸は水酸基またはアルキル基を表す。なお、Ｒ⁹およびｍは一般式（７）と同義である。）

(In the formula, R ⁸ represents a hydroxyl group or an alkyl group. R ⁹ and m have the same meaning as in formula (7).)

  In the obtained polymer compound I, the proportion of units derived from compound A in polymer compound I is preferably 10 to 70% by mass. More preferably, it is 30-70 mass%. When the content of the compound A unit is less than the above range, the polymer compound I having a sufficient image discoloration or fading preventing effect cannot be obtained. On the other hand, when the content of the compound A unit exceeds the above range, the resulting polymer compound I becomes expensive, and the aqueous coating solution used for forming the ink receiving layer using the polymer compound I In some cases, the solubility and dispersibility with respect to is poor. In addition, when the content of the compound A unit is in the above range and the solubility or dispersibility in the aqueous coating liquid is low, it can be improved by using a water-soluble organic solvent or a surfactant. Usable water-soluble organic solvents include, for example, alcohols such as methanol, ethanol, and propanol; lower alkyl ethers of polyhydric alcohols such as ethylene glycol, diethylene glycol, ethylene glycol monomethyl ether, and ethylene glycol dimethyl ether; acetone, methyl ethyl ketone, and the like Ketones; ethers such as tetrahydrofuran. Usable surfactants include cationic, nonionic, anionic low-molecular or high-molecular ones. The weight average molecular weight of the polymer compound I thus obtained is preferably in the range of 1,000 to 150,000 for the same reason as described later.

  In the polymer compound II used in the present invention, in the reaction of the compound A and the compound B, an amine compound C having two or more active hydrogen groups is further reacted, and the resulting compound C contains compound C. It is preferred to incorporate the unit and cationize at least some of the amino groups in the unit. The compound C is preferably a tertiary amine as represented by the following general formula (13).

（式中、Ｒ¹、Ｒ²、Ｒ³はいずれか一つが炭素数１〜６のアルキル基、アルカノール基、またはアミノアルキル基であり、それ以外は同一もしくは異なっていてもよく、アルカノール基、アミノアルキル基、またはアルカンチオール基を表す。）

(In the formula, any one of R ¹ , R ² , and R ³ is an alkyl group having 1 to 6 carbon atoms, an alkanol group, or an aminoalkyl group, and the others may be the same or different. Represents an aminoalkyl group or an alkanethiol group.)

  Specific examples of the compound represented by the general formula (13) include, for example, N-methyl-N, N-diethanolamine, N-ethyl-N, N-diethanolamine, N-isobutyl-N, N— as diol compounds. Examples include diethanolamine, Nt-butyl-N, N-diethanolamine, and Nt-butyl-N, N-diisopropanolamine. Examples of the triol compound include triethanolamine. Examples of the diamine compound include methyliminobispropylamine and butyliminobispropylamine, and examples of the triamine compound include tri (2-aminoethyl) amine. These amine compounds can be used alone or in combination of two or more to synthesize the polymer compound II used in the present invention.

  The polymer compound II used in the present invention reacts with compound A, compound B and compound C as described above, and the compound A unit, compound B unit and compound C unit (the tertiary amino group in the unit is cationized). Is obtained as a polymer containing in the molecule. In order to fully express the function of the polymer compound II, the content of the compound C in the polymer compound II is preferably in the range of 5.5 to 18.5% by molar ratio. When the content of Compound C is lower than 5.5% in terms of molar ratio, the content of hydrophilic groups decreases, making it difficult to prepare an aqueous dispersion of Polymer Compound II, and forming an ink receiving layer. In some cases, it may be difficult to blend the aqueous coating liquid. On the other hand, when the content of Compound C is higher than 18.5% in terms of molar ratio, there may be a problem that glossiness and print density are lowered in a recording medium containing the polymer compound II.

  In the polymer compound II used in the present invention, if the molar ratio of the compound C is in the above range, the compound C unit can occupy 3 to 80% by mass in the polymer compound II. When the content of the compound C in the polymer compound II is less than 3%, the water dispersibility of the polymer compound II itself as described above decreases, and when it exceeds 80%, the glossiness and print density of the recording medium decrease. May cause.

  In the polymer compound II used in the present invention, if the content of the compound C is in the range described above, the mass of the compound A unit incorporated in the polymer compound II is 10 to 65 in the polymer compound II. It is preferable to occupy% by mass. More preferably, it is the ratio which occupies 30-65 mass%. When the proportion of the compound A unit is less than 10% by mass, the image discoloration / fading prevention effect may be insufficient. On the other hand, when the proportion of the compound A unit exceeds 65% by mass, the content of the hydrophilic group is relatively lowered, which may be inconvenient when preparing an aqueous dispersion of the polymer compound II. .

  Compound B has a function of linking compound A and compound C, and the amount of compound B used is not particularly limited. However, if the content of compound C unit is in the range described above, the mass of compound B unit is: It is preferable to occupy 10 to 80% by mass in the obtained polymer compound II. More preferably, it is the ratio which occupies 30-60 mass%. When the proportion of the compound B unit is within this range, an amount sufficient to sufficiently exhibit the functions of each unit of the compound A and the compound C can be combined.

  The production method of the polymer compound II using the compounds A to C may be a so-called one-shot method in which the compounds A to C are reacted at once to form a random polymer, or the compound A (or the compound C) The so-called prepolymer method may be used in which a prepolymer having a terminal isocyanate group is produced by reacting the compound B with the compound B in a ratio rich in isocyanate groups, and the prepolymer and the compound C (or compound A) are reacted. Good. In any method, a chain extender such as a low molecular weight polyol or a low molecular weight diamine may be used in combination. The molecular weight of the obtained polymer compound II can be adjusted by changing the amount of compounds A to C used, or adding a reaction terminator such as monoalcohol or monoamine to the reaction system at an appropriate timing.

  The weight average molecular weight of the polymer compound I or II thus obtained is preferably in the range of 1,000 to 150,000, more preferably in the range of 2,000 to 50,000, although it depends on the reaction conditions. . If the weight average molecular weight of the polymer compound is less than 1,000, the glossiness and printing density may be lowered. If it exceeds 150,000, the reaction time becomes longer and the production cost increases, which is not preferable.

  In the production of the polymer compound I or II used in the present invention, a compound D having two or more active hydrogen groups other than the compound A and the compound C may be copolymerized as necessary. As such compound D, the following polyester polyols, polyether polyols, or polycarbonate polyols may be used alone, or two or more of them may be used simultaneously to synthesize polymer compound I or II used in the present invention. Is possible.

  Examples of the polyester polyol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, and 1,6-hexane. Diol, neopentyl glycol diol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol having a molecular weight of 300 to 1,000, dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanedimethanol, Glycol components such as bisphenol A, bisphenol S, hydrogenated bisphenol A, hydroquinone, alkylene oxide adducts, malonic acid, succinic acid, glutaric acid, adipine , Pimelic acid, suberic acid, azelaic acid, sebacic acid, hedecane dicarboxylic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bisphenoxyethane-p, p′-dicarboxylic acid, dicarboxylic acid Polyesters obtained by a ring-opening polymerization reaction of cyclic ester compounds such as ε-caprolactone, including polyesters obtained by dehydration condensation reaction from acid components such as anhydrides or ester-forming derivatives of These copolyesters are listed. I can get lost.

  Examples of the polyether polyol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexane. Diol, neopentyl glycol, glycerin, trimethylol ethane, trimethylol propane, sorbitol, sucrose, bisphenol A, bisphenol S, hydrogenated bisphenol A, aconitic acid, trimellitic acid, hemimellitic acid, phosphoric acid, ethylenediamine, diethylenetriamine, triisopropanol Compound having at least two active hydrogens such as amine, pyrogallol, dihydroxybenzoic acid, hydroxyphthalic acid, 1,2,3-propanetrithiol The product obtained by subjecting a product to addition polymerization by a conventional method using one or more monomers such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, and cyclohexylene as an initiator. It is done. As other polyether polyols, ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran using a compound having at least two primary amino groups such as ethylenediamine and propylenediamine as an initiator. In addition, one obtained by subjecting one or more monomers such as cyclohexylene to addition polymerization by a conventional method can also be used.

  Examples of the polycarbonate polyol include compounds obtained by reacting glycols such as 1,4-butanediol, 1,6-hexanediol, diethylene glycol and the like with diphenyl carbonate and phosgene.

  In the synthesis of the polymer compounds I and II used in the present invention, it is desirable to use a tin-based catalyst and / or an amine-based catalyst in the isocyanate polyaddition reaction. Examples of the tin-based catalyst include dibutyltin dilaurate and stannous octoate. Examples of the amine-based catalyst include triethylenediamine, triethylamine, tetramethylpropanediamine, tetramethylbutanediamine, and N-methylmorpholine. It is not limited to.

  The above-mentioned isocyanate polyaddition reaction can be carried out in the absence of a solvent depending on the composition, but a hydrophilic organic solvent that does not directly participate in the isocyanate polyaddition reaction system is reacted for the purpose of controlling the reaction system or controlling the base viscosity. It is common to use as a solvent. Examples of such hydrophilic organic solvents include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate. And organic acid esters such as methyl propionate, ethyl propionate and butyl propionate, and amines such as N, N-dimethylformamide and N-methylpyrrolidone. Moreover, it is preferable that the used hydrophilic organic solvent is finally removed.

  The polymer compound II used in the present invention is obtained by cationizing at least a part of the tertiary amino group of the compound C unit contained with an acid or a quaternizing agent before or after the synthesis of the polymer compound II. Can be dispersed or dissolved in water. In order to disperse or dissolve the polymer compound II in water with a preferred particle size described later, it is preferable to cationize with an acid, and it is more preferable to use phosphoric acid or a monovalent acid as the acid. Examples of phosphoric acid include phosphoric acid and phosphorous acid. Examples of the monovalent acid include organic acids such as formic acid, acetic acid, propionic acid, butyric acid, glycolic acid, lactic acid, pyruvic acid, and methanesulfonic acid, and inorganic acids such as hydrochloric acid and nitric acid. The reason why these acids are preferable is that the polymer compound II cationized using a polyvalent acid other than phosphoric acid may cause thickening when it is dispersed or dissolved in water. In addition, polymer compound II cationized with hydroxy acids such as glycolic acid and lactic acid, when applied to recording media, suppresses yellowing of white paper compared to polymer compound II cationized with other acids. In particular, it can be used preferably.

  Particularly preferred among the polymer compounds II used in the present invention obtained by the above method are compounds represented by the following general formulas (14) to (19).

（式中ｎは１または２を、Ｒ¹はメチレン基、エチレン基、またはプロピレン基を、Ｒ⁹はアルキレン、脂環を１つ以上含む二価の脂肪族炭化水素基もしくは芳香環を１つ以上含む二価の芳香族炭化水素基を、Ｒ¹⁰は炭素数１〜４のアルキル基を、Ｒ¹¹およびＲ¹²はそれぞれ独立で水素原子もしくはメチル基を、Ｘ^-は酸陰イオンを表す。ｍは重量平均分子量が１，０００〜１５０，０００になる数である。）

(Wherein n is 1 or 2, R ¹ is a methylene group, ethylene group or propylene group, R ⁹ is alkylene, one divalent aliphatic hydrocarbon group containing one or more alicyclic rings or one aromatic ring. The divalent aromatic hydrocarbon group containing the above, R ¹⁰ represents an alkyl group having 1 to 4 carbon atoms, R ¹¹ and R ¹² each independently represent a hydrogen atom or a methyl group, and X ⁻ represents an acid anion. m is a number having a weight average molecular weight of 1,000 to 150,000.)

（式中ｎは１または２を、Ｒ²およびＲ³はそれぞれ独立で水素原子、水酸基またはアルキル基を、Ｒ²およびＲ³は同一であっても異なっていてもよい。なお、Ｒ⁹〜Ｒ¹²、Ｘ^-およびｍは一般式（１４）と同義である。）

(A wherein n is 1 or 2, R ² and R ³ are independently a hydrogen atom, a hydroxyl group or an alkyl group, R ² and R ³ may be be the same or different. In addition, R ⁹ ~ R ¹² , X ⁻ and m have the same meanings as those in the general formula (14).)

（式中ｎは０または１を表す。Ｒ⁹〜Ｒ¹²、Ｘ^-およびｍは一般式（１４）と同義である。）

(In the formula, n represents 0 or 1. R ^{9 to} R ¹² , X ⁻ and m have the same meanings as those in the general formula (14).)

（式中ｎは１または２を、Ｒ⁴は硫黄原子または酸素原子を、Ｒ⁵は硫黄原子または−ＳＯ₂−を表し、Ｒ⁴およびＲ⁵は同一ではなく、それぞれ異なる基で構成される。なお、Ｒ⁹〜Ｒ¹²、Ｘ^-およびｍは一般式（１４）と同義である。）

(In the formula, n represents 1 or 2, R ⁴ represents a sulfur atom or an oxygen atom, R ⁵ represents a sulfur atom or —SO ₂ —, and R ⁴ and R ⁵ are not the same and are each composed of different groups. R ^{9 to} R ¹² , X ⁻ and m are as defined in the general formula (14).

（式中Ｒ⁶およびＲ⁷はそれぞれ独立で水素原子またはアルキル基を表し、Ｒ⁶およびＲ⁷は同一であっても異なっていてもよい。なお、Ｒ⁹〜Ｒ¹²、Ｘ^-およびｍは一般式（１４）と同義である。）

(Wherein R ⁶ and R ⁷ each independently represents a hydrogen atom or an alkyl group, and R ⁶ and R ⁷ may be the same or different. R ^{9 to} R ¹² , X ⁻ and m are (It is synonymous with general formula (14).)

（式中Ｒ⁸は水酸基またはアルキル基を表す。なお、Ｒ⁹〜Ｒ¹²、Ｘ^-およびｍは一般式（１４）と同義である。）

(In the formula, R ⁸ represents a hydroxyl group or an alkyl group. R ^{9 to} R ¹² , X ⁻ and m have the same meanings as those in the general formula (14).)

  When the polymer compounds I and II used in the present invention are dispersed in an aqueous medium, the average particle size of the dispersion is preferably in the range of 5 nm to 500 nm from the viewpoint of storage stability. In addition, the average particle diameter in the present invention is measured by a dynamic light scattering method, and is described in “Structure of polymer (2) Scattering experiment and morphology observation Chapter 1 Light scattering” (Edited by Kyoritsu Publishing Society of Polymer Science). Chem. Phys., 70 (B), 15 Apl., 3965 (1979). The average particle size defined in the present invention can be easily measured using, for example, a laser particle size analyzer PARIII (manufactured by Otsuka Electronics Co., Ltd.).

  The method for adding the polymer compound to the ink receiving layer is not particularly limited. For example, the polymer compound is directly added to a coating solution containing inorganic fine particles and a binder as described later, and applied in a batch system. The polymer compound is added to either the fine particle dispersion or the liquid containing the binder in advance, and coating is performed while continuously mixing with the liquid containing the binder or the fine particle dispersion immediately before coating. A method in which a polymer compound is dispersed in another aqueous medium and added in-line to a coating solution containing inorganic fine particles and a binder immediately before coating; and further, a coating solution containing inorganic fine particles and a binder is applied. There is a method of applying a liquid containing a polymer compound before and after the process, and any method can be used.

  Therefore, the recording medium of the present invention has a structure in which an ink receiving layer containing at least the polymer compound is provided on a support; a coating liquid containing the polymer compound is overcoated on the ink receiving layer. Or a configuration in which an ink receiving layer is formed by applying a small amount of a coating solution containing the polymer compound on the surface of the support. In the present invention, these configurations are also included as “an ink receiving layer formed on the surface of the support”.

  The content of the polymer compound used in the present invention is preferably 0.05 to 20% by mass (solid content conversion) of the ink receiving layer, and more preferably 0.05 to 15% by mass (solid content) of the ink receiving layer. %), More preferably 0.05 to 10% by mass (in terms of solid content) of the ink receiving layer. If the content is within this range, it is possible to effectively prevent discoloration of the image due to the oxidizing gas in the atmosphere. If the content of the ink receiving layer is less than 0.05% by mass, it is not possible to sufficiently prevent image discoloration, which is the object of the present invention. If the content exceeds 20% by mass, ink absorption is not possible. There is a risk of causing deterioration in printability and a decrease in print density.

  In the present invention, the inorganic fine particles that can be used for forming the ink-receiving layer are preferably fine particles that have high ink absorbability, excellent color developability, and can form high-quality images. Examples of such inorganic fine particles include calcium carbonate, magnesium carbonate, kaolin, clay, talc, hydrotalcite, aluminum silicate, calcium silicate, magnesium silicate, diatomaceous earth, alumina, colloidal alumina, aluminum hydroxide, and alumina hydrate. Products, synthetic amorphous silica, colloidal silica, lithopone, zeolite and the like, and these can be used alone or in combination.

  As the form of the inorganic fine particles, in order to obtain a highly glossy and highly transparent ink receiving layer, the average particle diameter is preferably in the range of 50 nm to 500 nm, more preferably in the range of 100 nm to 300 nm. When the average particle size of the inorganic fine particles is smaller than 50 nm, the ink absorbability of the ink receiving layer is remarkably reduced, and ink bleeding or beading (printing with a printer with a large discharge amount) Uneven phenomenon) occurs.

  On the other hand, when the average particle diameter is larger than 500 nm, the transparency of the ink receiving layer is lowered, and the print density and gloss of the image may be lowered. In addition, the average particle diameter as used in the field of this invention is measured by the dynamic light-scattering method, "A polymer structure (2) Scattering experiment and morphological observation Chapter 1 light scattering" (Kyoritsu Shuppan Polymer Society), Chem. Phys., 70 (B), 15 Apl., 3965 (1979).

  In the present invention, among the above-mentioned inorganic fine particles, silica, alumina, alumina hydrate, etc. can be preferably used, and furthermore, the ink receiving layer to be formed is excellent in transparency and smoothness and can form finer voids. In addition, alumina hydrate having a boehmite structure or a pseudoboehmite structure can be more preferably used because the particle surface has a positive charge and the fixability of the dye in the ink is good.

In particular, an alumina hydrate having a BET specific surface area of 50 m ² / g or more is preferable, more preferably in the range of 50 to 500 m ² / g, and still more preferably in the range of 50 to 250 m ² / g. When the BET specific surface area of alumina hydrate is in the range of 50 to 500 m ² / g, the ink-absorbing layer has excellent ink absorbability, beading, smoothness, and the like. On the other hand, when the BET specific surface area is less than 50 m ² / g, the transparency of the ink receiving layer and the print density are lowered, and the printed matter tends to be white and dull, and the BET specific surface area is low. If it exceeds 500 m ² / g, the ink absorptivity decreases, and a large amount of acid is required as a peptizer to stably disperse the alumina hydrate, which is not preferable.

The alumina hydrate having a boehmite structure or pseudoboehmite structure preferably used in the present invention is represented by the following general formula (20).
General formula (20)
Al ₂ O _3-n (OH) _2n · mH ₂ O
In the formula, n represents any one of integers of 0, 1, 2, or 3, and m represents a value of 0 to 10, preferably 0 to 5. Since mH ₂ O often represents a detachable aqueous phase that does not participate in the formation of a crystal lattice, m can take a non-integer value. Also, when this type of alumina hydrate is calcined, m can reach a value of zero.

  In general, an alumina hydrate crystal having a boehmite structure is a layered compound having a (020) plane forming a giant plane, and exhibits a diffraction peak peculiar to an X-ray diffraction pattern. As the boehmite structure, in addition to perfect boehmite, a structure called excess boehmite and containing excess water between layers of the (020) plane can be taken. The pseudo-boehmite X-ray diffraction pattern shows a broader diffraction peak than the complete boehmite. Since complete boehmite and pseudoboehmite are not clearly distinguishable, unless otherwise specified, they are both referred to as alumina hydrate showing a boehmite structure.

  Although it does not specifically limit as a manufacturing method of the said alumina hydrate, For example, any methods, such as a buyer method and a light van pyrolysis method, are employable. A particularly preferred method is a method in which an acid is added to a long-chain aluminum alkoxide for hydrolysis. In addition, the obtained alumina hydrate can be controlled to a specific range of the particle shape of the alumina hydrate by adjusting the conditions of the aging process for growing the particles through the hydrothermal synthesis process. When the time is set appropriately, primary particles of alumina hydrate having a relatively uniform particle diameter grow. The sol obtained here can be used as a dispersion by adding an acid as a peptizer, but in order to further improve the dispersibility of alumina hydrate in water, the sol is spray-dried, etc. After pulverizing by this method, an acid can be added to form a dispersion. Further, conventionally known acids can be used as the acid for peptizing alumina hydrate, such as formic acid, acetic acid, propionic acid, butyric acid, glycolic acid, lactic acid, pyruvic acid, methanesulfonic acid, and other organic acids, and Examples thereof include inorganic acids such as hydrochloric acid and nitric acid, and one or more of them can be freely selected and used.

  Further, instead of using an acid as a peptizer, a dispersion can be prepared using various surfactants or polymer dispersants. Further, a fine particle dispersion may be prepared by dispersing and peptizing inorganic fine particles in water using at least one of an organic acid and a cationic polymer.

  The solvent of the fine particle dispersion is not particularly limited as long as it is an aqueous medium such as water or a mixed solution with an organic solvent that can be mixed with water. Examples of organic solvents that can be mixed with water include alcohols such as methanol, ethanol, and propanol; lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl ether and ethylene glycol dimethyl ether; ketones such as acetone and methyl ethyl ketone; And ethers.

  In the present invention, an ink receiving layer is formed using a water-soluble resin and / or a water-dispersible resin together with the inorganic fine particles. Examples of the water-soluble resin or water-dispersible resin used in the present invention include gelatin, casein and modified products thereof, cellulose derivatives such as methylcellulose, carboxymethylcellulose, and hydroxyethylcellulose, fully or partially saponified polyvinyl alcohol or the like. Modified products (cation modification, anion modification, silanol modification, etc.), urea resins, melamine resins, epoxy resins, epichlorohydrin resins, polyurethane resins, polyethyleneimine resins, polyamide resins, polyvinylpyrrolidone resins, polyvinyl butyral Resin, poly (meth) acrylic acid or copolymer thereof, acrylamide resin, maleic anhydride copolymer, polyester resin, SBR latex, NBR latex, methyl methacrylate A cationic group or an anionic group is added to an acrylic polymer latex such as a butadiene copolymer latex or an acrylic ester copolymer, a vinyl polymer latex such as an ethylene-vinyl acetate copolymer, and these various polymer latexes. Examples thereof include functional group-modified polymer latexes. Preference is given to polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate and having an average degree of polymerization of 300 to 5,000. The saponification degree is preferably 70 to less than 100%, particularly preferably 80 to 99.5%. In addition, these water-soluble resins or water-dispersible resins can be used alone or in combination.

  The mixing mass ratio of the inorganic fine particles (A) and the water-soluble resin and / or water-dispersible resin (B) is preferably A: B = 1: 1 to 30: 1, more preferably A: B = 1. .5: 1 to 20: 1. If the amount of the water-soluble resin and / or the water-dispersible resin is within these ranges, the formed ink receiving layer will not easily crack or fall off, and the ink absorption will be good. Further, the method for mixing the inorganic fine particles with the water-soluble resin and / or water-dispersible resin is not particularly limited. Is dissolved, and this is mixed with the fine particle dispersion, and can be mixed by either a batch method or a continuous method.

  In the recording medium of the present invention, in order to improve the film forming property, water resistance and film strength of the film formed of the inorganic fine particles and the water-soluble resin and / or water-dispersible resin, A hardener may be added. Generally, various hardeners are selected depending on the type of reactive group possessed by the polymer used. For example, in the case of a polyvinyl alcohol resin, an epoxy hardener, a boron compound such as boric acid, Inorganic hardeners such as basic aluminum salts.

  The amount of the hardener used varies depending on the amount of the water-soluble resin and / or water-dispersible resin used as the binder, but is generally 0.1 to 30.0% by mass of the water-soluble resin and / or water-dispersible resin. It is good to add in a ratio. When the content of the hardener is less than 0.1% by mass of the water-soluble resin and / or the water-dispersible resin, the film-forming property is lowered and sufficient water resistance cannot be obtained. On the contrary, when it exceeds 30.0 mass%, the time-dependent change of coating-solution viscosity becomes large, and coating stability may fall.

  In addition, in the recording medium of the present invention, a cationic polymer is added to the ink receiving layer in a range that does not affect the ink absorbability in order to more effectively prevent bleeding of images under high temperature and high humidity. May be. As the cationic polymer, conventionally known ones can be used. For example, polyallylamine, polyaminesulfone, polyvinylamine, polyethyleneimine, polyamide epichlorohydrin resin, polyvinylpyridinium halide, polydimethyldiallylammonium chloride, polyacrylamide cation-modified product or acrylamide And cationic monomer copolymer, copolymer of vinyl pyrrolidone monomer and other general monomer, copolymer of vinyl oxazolidone monomer and other general monomer, vinyl imidazole monomer and other Examples include copolymers with common monomers, and these can be used alone or in combination of two or more.

  The solid content concentration in the coating liquid for forming the ink receiving layer is not particularly limited as long as the viscosity is such that the ink receiving layer can be formed on the support, but the total mass of the coating liquid is 5.0 to 50.0 mass% is preferable. If the solid content concentration is less than 5.0% by mass, it is necessary to increase the coating amount to increase the thickness of the ink receiving layer, and it takes much time and energy to dry, which is uneconomical. It is. Moreover, when it exceeds 50.0 mass%, the viscosity of a coating liquid will become high and coating property may fall.

  Moreover, various additives can be mix | blended with the said coating liquid in the range which does not prevent the effect of this invention. Such additives include antifoaming agents, ink fixing agents, dot adjusting agents, colorants, fluorescent brighteners, preservatives, pH adjusting agents, penetrating agents, antistatic agents, conductive agents, ultraviolet absorbers, oxidation agents Examples thereof include an inhibitor (anti-fading agent).

  As a method of coating the prepared coating liquid on the support, roll coater method, blade coater method, air knife coater method, gate roll coater method, bar coater method, size press method, spin coater method, spray coater method Conventionally known coating methods such as a gravure coater method, a curtain coater method, and a die coater method can be used. Thereafter, the ink receiving layer can be formed by drying using a drying apparatus such as a hot air dryer, a thermal drum, or a far infrared dryer. The ink receiving layer in the recording medium of the present invention may be formed in multiple layers by changing the composition ratios of inorganic fine particles, binder and other additives, and can be formed on one side or both sides of the support. It is. Further, for the purpose of improving the resolution and transportability of the image, smoothing processing may be performed using an apparatus such as a calendar or a cast.

A preferable range as the coating amount of the coating liquid on the support is 0.5 to 60.0 g / m ² in terms of solid content, and a more preferable range is 5.0 to 55.0 g / m ² . . When the coating amount is less than 0.5 g / m ² , the formed ink receiving layer may not sufficiently absorb the moisture of the ink, and the ink may flow or the image may blur. If it exceeds m ² , curling may occur during drying, or a remarkable effect may not be exhibited as expected for printing performance.

  The recording medium of the present invention obtained in this way is capable of high-quality image recording with excellent ink absorbability, image discoloration due to acid gas in the atmosphere, and image recording under high temperature and high humidity. Bleeding can be effectively prevented. Although the reason for preventing the discoloration and fading of the image is not clear, it is presumed that at least the polymer compound suppresses the generation of radicals and peroxides in the ink receiving layer. In addition, the reason why image bleeding under high temperature and high humidity was prevented was that the hydroxyl groups of Compound A and Compound C were greatly reduced due to polymerisation, and the inherent hygroscopicity was reduced. In addition, it is assumed that the bleeding that occurs when a non-water-absorbing support such as resin-coated paper is used as the support is caused by the high-boiling solvent contained in the ink and the solvent diffusing with the dye. Probably, in the recording medium of the present invention, the dye in the ink is adsorbed by the alumina fine particles of the ink receiving layer, and the organic solvent penetrates into the resin layer, so that the coloring material and the organic solvent are separated, and both the solvent and the dye diffuse. This is probably due to the fact that there is no longer anything to do.

  The ink used for recording an image on the recording medium of the present invention is not particularly limited, but a mixture of water and a water-soluble organic solvent is used as a medium, and a dye or pigment is dissolved or dispersed as a coloring material. The common water-based ink for ink jet recording can be preferably used.

  As a method for forming an image by applying the ink to the recording medium, an ink jet recording method is particularly preferable. As the ink jet recording method, the ink is effectively separated from the nozzle and the ink is applied to the recording medium. Any method may be used as long as it can provide the above. In particular, an ink jet system in which ink subjected to the action of thermal energy undergoes a rapid volume change by a method described in Japanese Patent Application Laid-Open No. 54-59936 and the like, and ink is ejected from a nozzle by the action force due to this state change. Can be used effectively.

  Hereinafter, the present invention will be described specifically by way of examples. In the following examples, “parts” and “%” are based on mass unless otherwise specified.

<Manufacture of support A>
Fine paper as a substrate (thickness: 145 μm, basis weight: 147.8 g / m ² , smoothness: 153 seconds) and cellophane film (thickness: 21 μm, basis weight: 29.5 g / m) as a material for the resin layer ² , contact angle: 22.3 °, water vapor transmission rate: 710 g / m ² · 24 hr), and an adhesive using a gravure coater on the cellophane film so that the dry coating amount is 6 g / m ^2. (Product name: Takelac A-520 and product name: Takenate A-50 (manufactured by Mitsui Takeda Chemical Co., Ltd.), mixing ratio: A-520 / A-50 = 4/1, solid after mixed dilution (Concentration: 25%) was applied, dried, and then laminated to fine paper to produce a support A.

<Manufacture of support B>
In the production method of the support A, the substrate was changed to coated paper (thickness: 178 μm, basis weight: 160.4 g / m ² , smoothness: 230 seconds) in the same manner as the production method of the support A. The support B was manufactured.

<Manufacture of support C>
In the manufacturing method of the support A, the material for the resin layer was changed to a polyvinyl alcohol film (thickness: 30 μm, contact angle: 28.5 °, moisture permeability: 370 g / m ² · 24 hr). A support C was produced in the same manner as in the above production method.

<Manufacture of support D>
In the production method of the support A, the material for the resin layer was changed to a polyvinyl alcohol film (thickness: 65 μm, contact angle: 32.3 °, moisture permeability: 100 g / m ² · 24 hr). A support D was produced in the same manner as in the above production method.

<Manufacture of support body E>
With reference to a conventionally known method for producing a cellulose casing, viscose is applied onto fine paper (thickness: 145 μm, basis weight: 147.8 g / m ² , smoothness: 153 seconds), and recycled to a thickness of 30 μm. A support film E was produced by forming a cellulose membrane. The contact angle of the cellulose membrane surface was 23.5 °, and the moisture permeability was 590 g / m ² · 24 hr (the moisture permeability of the cellulose membrane was a value obtained by subtracting the moisture permeability of the substrate from the moisture permeability of the support E). Is).

<Support F>
Polyethylene-coated paper as support F (polyethylene coating layer thickness: 30 μm, polyethylene coating layer contact angle: 96.8 °, polyethylene coating layer moisture permeability: 15 g / m ² · 24 hr, 60 according to JIS-Z-8741 Degree of specular gloss: 64%).

<Evaluation 1: Evaluation about smoothness>
The smoothness of the supports A to F was measured using a Oken type smoothness tester (manufactured by Asahi Seiko Co., Ltd.). The results are shown in Table 1.

<Manufacture of alumina hydrate and dispersion thereof>
Aluminum dodexide was produced by the method described in US Pat. No. 4,242,271. Next, the aluminum dodexide was hydrolyzed by the method described in US Pat. No. 4,202,870 to produce an alumina slurry. Water was added to the alumina slurry until the solid content of alumina hydrate was 7.7%. At this time, the pH of the alumina slurry was 9.4, and the pH was adjusted by adding a 3.9% nitric acid solution thereto. Next, using an autoclave, aging was carried out at pH before aging: 6.0, aging temperature: 150 ° C., and aging time: 6 hours to obtain a colloidal sol. This colloidal sol was spray-dried at an inlet temperature of 87 ° C. to obtain alumina hydrate powder.

Further, 27.3 parts of the obtained alumina hydrate and 9.10 parts of 6% -acetic acid aqueous solution (2% of the alumina hydrate) were added to 100 parts of ion-exchanged water, and a three-one motor (trade name: BL600, manufactured by Shinto Kagaku Co., Ltd.) was stirred at 350 rpm for 10 minutes to prepare an alumina dispersion having a solid content concentration of 20%. Moreover, when the obtained alumina dispersion liquid was dried and pulverized at 60 degreeC and the crystal structure was analyzed using the X-ray-diffraction apparatus (X'Pert-PRO, the product made by PANalytical), the boehmite structure was shown. Furthermore, when the specific surface area was measured by the following method, it was 139.7 m ² / g.

<Method for measuring specific surface area>
Alumina dispersion was dried at 60 ° C. to be powdered, further vacuum degassed at 120 ° C. for 24 hours, and then a specific surface area / pore distribution measuring device (TriStar3000, manufactured by Micromeritics (Shimadzu Corporation)) Was used to determine the specific surface area by the BET method. Nitrogen was used as the adsorption gas.

<Method for producing polymer compound a>
Polymer compound a was produced as follows.
A reaction vessel equipped with a stirrer, a thermometer and a reflux condenser was charged with 109 g of acetone as a reaction solvent, and 40.00 g of 3,6-dithia-1,8-octanediol and 6.79 g of methyldiethanolamine were dissolved under stirring. Thereafter, the temperature was raised to 40 ° C. and 62.07 g of isophorone diisocyanate was added. Thereafter, the temperature was raised to 50 ° C., 0.2 g of a tin-based catalyst was added, the temperature was further raised to 55 ° C., and the reaction was performed for 4 hours while stirring.

  After completion of the reaction, the reaction solution was cooled to room temperature and cationized by adding 3.09 g of 85% formic acid. After further adding 446 g of water, concentration was performed under reduced pressure to remove acetone, and the concentration was further adjusted with water to produce a polymer compound aqueous dispersion (polymer compound a) having a solid content of 20%.

<Method for producing polymer compound b>
Polymer compound b was produced as follows.
A reaction vessel equipped with a stirrer, a thermometer and a reflux condenser is charged with 81 g of acetone as a reaction solvent, 30.00 g of 3,6-dithia-1,8-octanediol and t-butyldiethanolamine are added under stirring. After dissolving 98 g, the temperature was raised to 40 ° C. and 44.28 g of isophorone diisocyanate was added. Thereafter, the temperature was raised to 50 ° C., 0.4 g of a tin-based catalyst was added, the temperature was further raised to 55 ° C., and the reaction was carried out for 5 hours while stirring.

  After completion of the reaction, the reaction solution was cooled to room temperature and cationized by adding 4.51 g of 35% hydrochloric acid. Further, 331 g of water was added, and then a polymer compound aqueous dispersion (polymer compound b) having a solid content of 20% was produced in the same manner as in the method of producing polymer compound a.

<Method for producing polymer compound c>
Polymer compound c was produced as follows.
A reaction vessel equipped with a stirrer, a thermometer and a reflux condenser is charged with 258 g of acetone as a reaction solvent, 40.00 g of 5-hydroxy-3,7-dithia-1,9-nonanediol and methyldiethanolamine with stirring. After dissolving 6.29 g, the temperature was raised to 40 ° C. and 54.17 g of isophorone diisocyanate was added. Thereafter, the temperature was raised to 50 ° C., 0.1 g of a tin-based catalyst was added, the temperature was further raised to 55 ° C., and the reaction was carried out for 2 hours while stirring.

  After completion of the reaction, the reaction solution was cooled to room temperature and cationized by adding 2.86 g of 85% formic acid. Further, 412 g of water was added, and a polymer compound aqueous dispersion (polymer compound c) having a solid content of 20% was produced in the same manner as in the method for producing polymer compound a.

<Method for producing polymer compound d>
Polymer compound d was produced as follows.
Into a reaction vessel equipped with a stirrer, a thermometer, and a reflux condenser, 140 g of acetone as a reaction solvent is added, and 68.13 g of 3,6-dithia-1,8-octanediol is dissolved with stirring, and then the temperature is raised to 40 ° C. On warming, 79.66 g of isophorone diisocyanate was added. Thereafter, the temperature was raised to 50 ° C., 0.4 g of a tin-based catalyst was added, the temperature was further raised to 55 ° C., and the reaction was carried out for 4 hours while stirring.

  After completion of the reaction, the reaction solution was cooled to room temperature, and then 1190 g of acetone was added to prepare a polymer compound acetone solution having a solid content of 10% to produce polymer compound d.

Table 2 shows synthesis components of the polymer compounds a to d and mass ratios thereof. Table 3 shows the weight average molecular weight and molecular weight distribution (Mw / Mn) measured by GPC (Gel Permeation Chromatography, controller: SC8010, detector: RI8012, manufactured by Tosoh Corporation). In addition, absorption (1,730 to 1,690 cm ⁻¹ C═O stretching vibration, 1,540 cm ⁻ ) showing the characteristics of a urethane group by an infrared spectrophotometer (FT / IR-5300, manufactured by JASCO Corporation). ¹ near N-H deformation vibration, since the detection of the 3,450～3,300Cm N-H stretching vibration in the vicinity of ^-1), occurs polymerized in all reactions, that raw material components was polymerized confirmed.

  The polymer compounds a to c in Table 2 are 20% aqueous dispersions, and the polymer compound d is a 10% acetone solution.

<Example 1>
To 100 parts of the previously prepared alumina dispersion, 0.4 part of boric acid (20% of polyvinyl alcohol) and 10 parts of polymer compound a are added, and 10 parts of polyvinyl alcohol (PVA224, manufactured by Kuraray Co., Ltd.) are added. A coating solution was prepared by adding 20 parts of a 10% aqueous solution (10% of alumina hydrate) and stirring with a three-one motor until uniform. This coating solution was applied onto the support A with a Mayer bar so that the dry coating amount was 35 g / m ^2, and a blower constant temperature dryer (manufactured by Toyo Seisakusho Co., Ltd., trade name: FC-610). ) At 110 ° C. for 20 minutes to produce a recording medium of the present invention. The following evaluations 2 to 5 were performed on the obtained recording medium. The results are shown in Table 4.

Various properties of the obtained recording medium were evaluated in the following manner.
<Evaluation 2: Evaluation method for glossiness>
Using a gloss meter (trade name: VG-2000, manufactured by Nippon Denshoku Industries Co., Ltd.), the 75-degree specular gloss specified by JIS-Z-8741 on the surface of the ink receiving layer of the recording medium was measured. . The results are shown in Table 4.

<Evaluation 3: Evaluation method for ink absorbency>
Using an ink jet printer (trade name: BJ F870, manufactured by Canon Inc.), the ink ratio is 90% to 270%, and the mixing ratio of green (cyan ink / photocyan ink / yellow ink is 85). (90/100) was printed, and the ink absorbency was evaluated by obtaining the maximum driving amount at which no beading occurred. An ink ejection amount of 200% or more is indicated by “◯”, an ink ejection amount of 170% or more and less than 200% is indicated by “△”, and an ink ejection amount of less than 170% is indicated by “X”. . The results are shown in Table 4.

<Evaluation 4: Evaluation method for image bleeding under high temperature and high humidity>
Solid printing of black (mixing ratio of cyan ink / magenta ink / yellow ink: 50/50/50, ink ejection amount: 150%) using an inkjet printer (trade name: BJ F870, manufactured by Canon Inc.) The sample was exposed to an environment of 30 ° C. and 80% RH for 1 week, and the degree of image blurring was visually evaluated. The case where bleeding did not occur was indicated as “◯”, the case where slight bleeding occurred as “Δ”, and the case where blurring occurred as “×”. The results are shown in Table 4.

<Evaluation 5: Evaluation method for fading / discoloration suppression effect by gas>
Using an ink jet recording apparatus (BJ F870, manufactured by Canon Inc.), a black (Bk) ink and a cyan (C) ink were printed in a single color and solidly printed with an ink ejection amount of 100%. After putting it in a tester (made by Suga Test Instruments Co., Ltd., special order) and exposing it to ozone at a concentration of 1 ppm under the conditions of 40 ° C. and 55% RH, the optical density of Bk and C was measured with an optical reflection densitometer (Greta). It was measured using Macbeth Co., Ltd. (RD-918). Next, the remaining OD rate is calculated from the following formula (3). When the remaining OD rate is 80% or more, “◯”, when the remaining OD rate is 60% or more and less than 80%, “△”, the remaining OD rate The evaluation was made with “x” when less than 60%. The results are shown in Table 4.
Residual OD rate = (OD after test / OD before test) × 100% Formula (3)

<Examples 2 to 5>
A recording medium was produced in the same manner as in Example 1 except that the support A was changed to the supports B to E in Example 1, and the tests of evaluations 2 to 5 were performed. The results are shown in Table 4.

<Example 6 and Example 7>
A recording medium was prepared and evaluated in the same manner as in Example 1 except that the polymer compound a was changed to the polymer compound b (Example 6) and the polymer compound c (Example 7) in Example 1. Two to five tests were performed. The results are shown in Table 4.

<Example 8>
In Example 1, except that the polymer compound a was not added, a coating solution was prepared in the same manner as in Example 1 to form an ink receiving layer on the support A. Thereafter, the polymer compound d (10% acetone solution) is overcoated with a Mayer bar on the ink receiving layer so that 10% (in terms of solid content) of the alumina hydrate in the ink receiving layer is added, and the air blowing constant temperature. The ink receiving layer containing the polymer compound d was formed by drying at 110 ° C. for 10 minutes using a dryer (Toyo Seisakusho, FC-610). (However, the ink receiving layer overcoated with the polymer compound d was adjusted so that its dry weight was 35 g / m ² ). A recording medium having an ink receiving layer overcoated with the polymer compound d was prepared by the above method, and tests 2 to 5 were performed. The results are shown in Table 4.

<Comparative Example 1>
In Example 1, a recording medium was prepared in the same manner as in Example 1 except that the support A was changed to the support F and the polymer compound was not added, and the tests of evaluations 2 to 5 were performed. . The results are shown in Table 4.

<Comparative example 2>
A recording medium was prepared in the same manner as in Example 1 except that the support A was changed to the support F in Example 1, and the tests of evaluations 2 to 5 were performed. The results are shown in Table 4.

<Comparative Example 3>
In Example 6, except that the support A was changed to the support F, a recording medium was prepared in the same manner as in Example 6, and the tests 2 to 5 were performed. The results are shown in Table 4.

<Comparative Example 4>
In Example 7, except that the support A was changed to the support F, a recording medium was prepared in the same manner as in Example 7, and the tests of evaluations 2 to 5 were performed. The results are shown in Table 4.

<Comparative Example 5>
A recording medium was produced in the same manner as in Example 8 except that the support A was changed to the support F in Example 8, and the tests 2 to 5 were performed. The results are shown in Table 4.

<Comparative Example 6>
A recording medium was obtained in the same manner as in Example 1 except that the support A was changed to fine paper (thickness: 145 μm, basis weight: 147.8 g / m ² , smoothness: 153 seconds) in Example 1. It produced and the test of evaluation 2-5 was done. The results are shown in Table 4.

<Comparative Example 7>
A recording medium was obtained in the same manner as in Example 1 except that the support A was changed to coated paper (thickness: 178 μm, basis weight: 160.4 g / m ² , smoothness: 230 seconds) in Example 1. It produced and the test of evaluation 2-5 was done. The results are shown in Table 4.

  As is apparent from Table 4, the recording medium produced using the support of the present invention is capable of high-quality image recording excellent in glossiness and ink absorbability, and is capable of recording an image by acid gas in the atmosphere. Discoloration was effectively prevented, and the effect of preventing image bleeding under high temperature and high humidity was excellent.

  According to the present invention, by using a support having a resin layer having ink absorbability and / or ink permeability on a substrate, an ink receiving layer having excellent gloss can be formed without performing a smoothing treatment. In addition, it was possible to provide a recording medium that was excellent in image discoloration and discoloration due to acid gas in the atmosphere and effectively prevented bleeding of the image under high temperature and high humidity.

Claims (5)

  In a recording medium in which an ink receiving layer is provided on at least one surface of a support, the support has at least one resin layer having ink absorbability and / or ink permeability on a substrate, and A recording medium, wherein the ink receiving layer laminated on the resin layer contains a polymer compound obtained by reacting a sulfur-containing organic compound. The recording medium according to claim 1, wherein the moisture permeability of the resin layer satisfies the following formula (1).
Moisture permeability of resin layer ≧ 100g / m ² · 24hr Formula (1) The recording medium according to claim 1, wherein the smoothness of the surface of the support satisfies the following formula (2).
Smoothness of support surface ≧ 300 seconds Formula (2) The recording medium according to claim 1, wherein the polymer compound is a compound obtained by reacting at least the following compound A and compound B.
A: Sulfur-containing organic compound having two or more active hydrogen groups B: Polyisocyanate compound having two or more isocyanate groups   The recording medium according to claim 1, wherein the support has water absorption.