JP4064362B2 - Inkjet recording medium - Google Patents

Description

  The present invention relates to an ink jet recording medium, and more particularly to an ink jet recording medium excellent in ink absorbability.

  The ink jet recording method forms dots by attaching small droplets of ink ejected by various mechanisms onto the recording paper. There is no noise compared to the dot impact type recording method, and full color is easy. In addition, there are advantages such as high-speed printing.

  In recent years, image data has also become highly detailed due to the widespread use of high-resolution digital video (camera), scanners, and personal computers. However, due to the high performance of inkjet printers, these image data have the same quality as silver halide photographs. Output (hard copy) is available. Along with this, the inkjet recording medium is required to have glossiness equivalent to a silver salt photograph and high image quality characteristics.

As an ink jet recording paper satisfying the above characteristics, a technique has been proposed in which an ink receiving layer containing a pigment, a binder, and a water-soluble plasticizer is formed on the surface of a base paper (see, for example, Patent Document 1). Usually, when the amount of silica is increased in order to improve the ink absorbency and improve the image quality, there is a problem that the bonding force between the silicas weakens and the coating layer is cracked. However, according to this technique, ink absorbability and crack resistance can be improved by adding sorbitol having a plastic effect to polyvinyl alcohol as a binder to the ink receiving layer.
On the other hand, a so-called cast coating method is disclosed as a technique for obtaining a highly glossy ink jet recording sheet (see, for example, Patent Document 2). In the cast coating method, a wet ink receiving layer is pressed against a heated mirror-finished surface (mirror drum) via a press roll and dried. At this time, a good glossy surface can be obtained by copying the glossy surface of the drum surface onto the ink receiving layer.

Japanese Patent Laid-Open No. 2001-10211 Japanese Patent Laid-Open No. 2-27487

However, even when the above technique is used, it is not possible to prevent the occurrence of paper dust due to the coating layer (ink receiving layer) dropping off during cutting or handling of the inkjet recording paper. When the paper dust adheres to the surface of the recording paper, there arises a problem that an image defect occurs. In particular, when the cast coating method is used, the above-mentioned problem of powder falling becomes remarkable.
Accordingly, an object of the present invention is to provide an ink jet recording medium that has good ink jet recording quality, particularly ink absorbability, and is less likely to cause powder falling.

As a result of intensive studies on the above problems, the present inventors have found that the above problems can be solved by providing an under layer below the ink receiving layer. That is, usually, when cutting an inkjet recording paper, a crack is generated from a thin (soft) portion of the coating layer caused by coating unevenness of the ink receiving layer. For this reason, it is considered that the cut edge is not a vertical surface but irregularities, and the coating layer is peeled off from the convex portions to generate paper dust.
On the other hand, when an under layer containing sugar alcohol is present, the polyvinyl alcohol in the under layer is plasticized by the sugar alcohol, and the under layer absorbs deformation of the ink receiving layer during cutting. For this reason, it is considered that the thin cut portion of the coating layer does not forcibly cut, and the cut edge becomes a clean vertical surface, and the dropout of the pigment in the ink receiving layer is reduced.

That is, the inkjet recording medium of the present invention is provided with at least one under layer containing a pigment, 15 to 60 parts by mass of polyvinyl alcohol, and sorbitol or xylitol with respect to 100 parts by mass of the pigment on at least one side of the support. One or more ink receiving layers containing a pigment and a binder are provided on the surface of the under layer.

The oil absorption of the pigment in the under layer is preferably 100 to 300 ml / 100 g, and the molecular weight of the sorbitol or xylitol is preferably 100 to 400 and the melting point is preferably 70 to 180 ° C.
The pigment of the under layer is preferably synthetic silica, and the ink receiving layer is preferably formed by a cast coating method.
It is preferable that 0.05 to 10 parts by mass of the sorbitol or xylitol is contained in the under layer.

  According to the present invention, it is possible to obtain an ink jet recording medium that has good ink jet recording quality, particularly ink absorbability, and that is less likely to fall off during cutting. In particular, a powder fall-off suppressing effect is large in an ink jet recording medium using a cast coating method.

  Hereinafter, embodiments of the present invention will be described. In the ink jet recording medium of the present invention, an under layer and an ink receiving layer are provided in this order on at least one surface of a support.

<Support>
As the support, known materials can be appropriately selected and used, but it is particularly preferable to use paper (coated paper, uncoated paper, etc.). Paper pulp includes chemical pulp (coniferous bleached or unbleached kraft pulp, hardwood bleached or unbleached kraft pulp, etc.), mechanical pulp (ground pulp, thermomechanical pulp, chemithermomechanical pulp, etc.), deinked pulp Etc. may be used singly or in an arbitrary ratio. The pH of the paper may be any of acidic, neutral and alkaline. Moreover, it is preferable to improve the opacity of paper by containing a filler in the paper. The filler can be appropriately selected from known fillers such as hydrated silicic acid, white carbon, talc, kaolin, clay, calcium carbonate, titanium oxide, and synthetic resin filler.

<Under layer>
The under layer contains a pigment, polyvinyl alcohol, and sugar alcohol.
[Pigment]
Examples of pigments include synthetic silica, alumina and alumina hydrate (alumina sol, colloidal alumina, pseudoboehmite, etc.), aluminum silicate, magnesium silicate, magnesium carbonate, light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, and dioxide. Inorganic pigments such as titanium, zinc oxide, zinc carbonate, calcium silicate, and aluminum hydroxide, and organic pigments such as plastic pigments and urea resins can be used.

  The oil absorption of the pigment is preferably 100 to 300 ml / 100 g, more preferably 150 to 250 ml / 100 g. Conventionally, it has been known that increasing the oil absorption amount of the pigment improves the ink absorbency, but it has been found by the present inventors that if the oil absorption amount is too large, the paper powder tends to increase. Stipulate the above range. When the oil absorption is less than 100 ml / 100 g, the ink absorbability is not sufficient, and when it exceeds 300 ml / 100 g, the paper dust tends to increase.

In the present invention, it is particularly preferable to use synthetic silica. By containing synthetic silica in the under layer, ink absorbability can be imparted. That is, in the present invention, the ink absorbability is ensured by adding a pigment to the ink receiving layer described later, but the ink absorbability is further improved by including the pigment in the under layer.
As the synthetic silica, silica produced by a wet method such as a gel method or a precipitation method, calcium carbonate composite silica, or the like can be used. Silica produced by the gel method and dry-pulverized (having a large specific surface area and a dense aggregate structure) can also be used. In particular, when calcium carbonate composite silica is used, both ink absorptivity and powder fall-off prevention can be satisfied. Calcium carbonate composite silica (CaCO ₃ · nSiO ₂₎ is sodium silicate (Na ₂ O · nSiO ₂₎ to carbon dioxide in the calcium chloride calcium silicate obtained by reacting _{(CaCl 2) (CaO · nSiO} 2) (CO ₂ ) can be easily obtained by blowing. In addition, the surface of wet-pulverized heavy calcium carbonate is modified with a cationic polymer to form a composite of silica, whereby calcium carbonate composite silica can be obtained.

  The pigment content is preferably 60 to 80% by mass, more preferably 65 to 75% by mass, based on the mass of the under layer. When the pigment content exceeds 80% by mass, the ink absorbability is improved, but the strength of the under layer is reduced, paper dust is generated due to the falling off of the layer, and handling is deteriorated. When the amount of the pigment is less than 60% by mass, the ink absorbability is deteriorated.

[Polyvinyl alcohol]
Polyvinyl alcohol (PVA) functions as a binder. Polyvinyl alcohol is more transparent than other binders, has good color development of printed images, and has higher coating strength than other binders, and can maintain binding power even with a small amount. The amount of the binder that enters the pores in the coating layer is reduced, and as a result, the voids in the coating layer can be maintained. And when the space | gap of a coating layer increases, ink absorptivity will improve.

  The saponification degree and polymerization degree of polyvinyl alcohol can be appropriately selected. Polyvinyl alcohol is preferably contained alone in the under layer, but other binders, for example, starches such as oxidized starch and esterified starch, carboxymethylcellulose, hydroxyethylcellulose, etc., as long as the effects of the present invention are not impaired. Cellulose derivatives, polyvinylpyrrolidone, casein, gelatin, soy protein, styrene-acrylic resin and derivatives thereof, styrene-butadiene latex, acrylic emulsion, vinyl acetate emulsion, vinyl chloride emulsion, urethane emulsion, urea emulsion, alkyd emulsion, and derivatives thereof May be used in combination.

  It is preferable that the compounding quantity of polyvinyl alcohol is 15-60 mass parts with respect to 100 mass parts of pigments, and it is especially preferable that it is 20-50 mass parts. When the blending amount of PVA is less than 15 parts by mass, the binding force between the pigments becomes small, the coating layer strength decreases, and the coating layer is missing. On the other hand, if the blending amount exceeds 60 parts by mass, a part of the binder remains adsorbed on the pigment particles even after coating, so that the ink absorption capacity of the under layer becomes insufficient. When a binder other than polyvinyl alcohol is contained as the binder, the total amount of the binder is blended within the above range.

[Sugar alcohol]
Sugar alcohol is used to plasticize polyvinyl alcohol, and it is considered that the under layer can be softened by plasticization, and the under layer can absorb the deformation of the ink receiving layer at the time of cutting. Moreover, since sugar alcohol is excellent in film property, an under layer can be made flexible. Further, the ink receiving layer and the under layer tend to be hard and brittle in a low humidity state, but tend to be flexible in a high humidity state. And since sugar alcohol itself has moisturizing property, it is conceivable to increase the moisture in the paper and to make the ink receiving layer and the under layer flexible by containing sugar alcohol. For these reasons, it is considered to be effective in reducing paper dust during cutting.
Normally, cutting of the ink jet recording medium is performed with a guillotine cutter or the like. The guillotine cutter has, for example, a cutting blade whose one side is flat and the other side is thin toward the tip, and the cutting blade is lowered from above the lithographic paper aligned on the metal flat plate and cut. It has become.

Sugar alcohol is a general term for compounds in which hydrogen is added to a saccharide (catalytic reduction) to change the terminal to alcohol, and examples thereof include sorbitol, maltitol, xylitol, erythritol, paratinite, lactitol, and mannitol. It is not limited. In addition, when optical isomers (D-form and L-form) are present in the sugar alcohol, any isomer may be used in the present invention, or a mixture thereof may be used.
In particular, when a sugar alcohol having a molecular weight of 100 to 400 and a melting point of 70 to 180 ° C. is used, the plastic effect of polyvinyl alcohol increases and paper dust can be effectively suppressed. Sorbitol falls under this range of sugar alcohols.

  The amount of the sugar alcohol is preferably 0.05 to 10 parts by mass, more preferably 0.5 to 5 parts by mass in the under layer. When the blending amount is less than 0.05 parts by mass, paper dust is generated during cutting, and the cut surface is rough and fluffed. On the other hand, if the blending amount exceeds 10 parts by mass, the stickiness of the recording medium may increase, or the stability of the underlayer coating material may deteriorate and coating may become difficult.

The coating amount of the under layer is preferably 4 to ²⁰ g / m ² . When the coating amount is less than 4 g / m ² , the ink absorbability is not sufficient and causes bleeding, and when it exceeds 20 g / m ² , the coating amount is excessive and the productivity is deteriorated.

<Ink receiving layer>
An ink receiving layer including a pigment and a binder is provided on the surface of the under layer.
[Pigment]
The pigment is an essential component for improving the ink absorbability in the ink receiving layer. Examples of pigments include synthetic silica, alumina and alumina hydrate (alumina sol, colloidal alumina, pseudoboehmite, etc.), aluminum silicate, magnesium silicate, magnesium carbonate, light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, and dioxide. Inorganic pigments such as titanium, zinc oxide, zinc carbonate, calcium silicate, and aluminum hydroxide, and organic pigments such as plastic pigments and urea resins can be used. In particular, alumina hydrate is preferable from the viewpoint of ink absorbability and gloss, and alumina is more preferable. Alumina and alumina hydrate are preferably used in combination with synthetic silica.
If no pigment is blended in the ink receiving layer, paper dust is not generated at the time of cutting, but the ink absorptivity is reduced, so that an ink jet recording medium with high image quality cannot be obtained.

[Binder]
As a binder, the well-known binder used for the conventional coated paper can be used. In particular, when polyvinyl alcohol is used, the transparency of the ink receiving layer is improved, and a high gloss comparable to that of a silver salt photograph is obtained. Further, the print density is improved and a vivid recorded image can be obtained. The saponification degree and polymerization degree of polyvinyl alcohol can be appropriately selected. In addition to polyvinyl alcohol, other binders, such as oxidized starch, starch such as esterified starch, cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, polyvinylpyrrolidone, casein, gelatin, as long as the effects of the present invention are not impaired. , Soy protein, styrene-acrylic resin and derivatives thereof, styrene-butadiene latex, acrylic emulsion, vinyl acetate emulsion, vinyl chloride emulsion, urethane emulsion, urea emulsion, alkyd emulsion, and derivatives thereof may be used in combination.

Although the compounding quantity of a binder is not specifically limited as long as required layer strength is obtained, it is preferable to set it as 5-30 mass parts with respect to 100 mass parts of pigments, and it is more preferable to set it as 5-20 mass parts. When the blending amount is less than 5 parts by mass, the layer strength tends to decrease, and when it exceeds 30 parts by mass, the blending ratio of the pigment decreases and the ink absorbency tends to decrease.
In addition, when polyvinyl alcohol and another binder are used together as a binder, it is preferable that the ratio of polyvinyl alcohol with respect to the whole binder Z is 30 mass% or more, especially 50 mass% or more. When the proportion of polyvinyl alcohol is less than 30% by mass, the glossiness of white paper tends to be difficult to be obtained.

The coating amount of the ink receiving layer can be arbitrarily adjusted within the range that covers the surface of the support and sufficient ink absorbency can be obtained, but from the viewpoint of achieving both print density and ink absorbency, , and particularly preferably it is 5 to 30 g / ^{m 2} in terms of solid content is preferably, when considering the productivity 10 to 25 g / ^{m 2.} When the coating amount exceeds 30 g / m ² , the releasability from a mirror drum, which will be described later, decreases, and problems such as the coating layer adhering to the mirror drum occur. In the case where the ink receiving layer contains a pigment and polyvinyl alcohol, conventionally, when the coating amount exceeds 10 g / m ² , paper dust is generated at the time of cutting. However, according to the present invention, generation of paper dust can be suppressed, The coating can exceed 10 g / m ² .

<Difference between under layer and ink receiving layer>
The under layer and the ink receiving layer can be easily distinguished by observing the cross section of the ink jet recording medium with an electron microscope or the like. In particular, when the ink receiving layer is provided by the cast coating method, a lot of voids are seen in the under layer, whereas the cast layer (ink receiving layer) has few voids and looks like a uniform layer with no distinction between pigment and binder. .
In addition, since there exists a possibility that color developability may fall, it is preferable that sorbitol is not included in an upper layer from an under layer.

  The under layer and the ink receiving layer can be formed by applying a coating liquid containing a predetermined component. In this coating liquid, pigment dispersants, water retention agents, thickeners, antifoaming agents, antiseptics, colorants, water resistance agents, wetting agents, fluorescent dyes, UV absorbers, cationic polymers are optionally added. An electrolyte or the like can be added as appropriate.

  Known methods such as blade coater, air knife coater, roll coater, brush coater, kiss coater, squeeze coater, curtain coater, die coater, bar coater, gravure coater, comma coater, etc. It can select suitably from the methods using the coating machine.

<Cast coat>
In the present invention, preferably, the ink receiving layer is formed by a cast coating method, whereby a high gloss comparable to a silver salt photograph can be obtained. In the cast coating method, a wet ink receiving layer is pressed against a heated mirror-finished surface (mirror drum) via a press roll and dried. At this time, a good glossy surface can be obtained by copying the glossy surface of the drum surface onto the ink receiving layer. In particular, a so-called “coagulation cast coating method” in which a liquid for coagulating an ink receiving layer (hereinafter referred to as “coagulating liquid”) is applied to a wet ink receiving layer and then pressed onto a mirror finished surface is a so-called “coagulation cast coating method”. Copying is easy, and minute unevenness on the surface of the ink receiving layer can be reduced, so that it is easy to obtain a high gloss equivalent to a silver salt photograph.
On the other hand, when the surface of the ink receiving layer is made glossy by using the cast coating method, powder falling off at the time of cutting, roughness of the cut surface and fluffing are more noticeable than in the case of a normal mat surface. Thus, the above problems can be prevented.

  In the present invention, it is preferable to apply a coagulation cast coating method using a treatment liquid containing polyvinyl alcohol as a binder in the ink receiving layer and coagulating polyvinyl alcohol as the coagulation liquid. Examples of the treatment liquid include a liquid containing both boric acid and borate.

  Here, when borate is used alone, the coagulation action of borate and polyvinyl alcohol in the ink receiving layer is too strong, and the glossy surface of the mirror drum surface cannot be sufficiently copied to the ink receiving layer, which is good. It is difficult to obtain a glossy surface. On the other hand, when boric acid is used alone, the coagulation action of polyvinyl alcohol and boric acid in the ink receiving layer becomes insufficient, and the soft-coagulated ink receiving layer may adhere to the roll to which the treatment liquid is applied. It is difficult for the solidified state to become good. Even if the concentration of boric acid in the treatment liquid is increased to enhance the coagulation effect, the solubility of boric acid is low, so there is a limit to the increase in concentration, and it is difficult to coagulate to a desired hardness.

  For the above reasons, in the present invention, it is preferable to use a treatment liquid in which borate and boric acid are mixed. By doing so, it becomes easy to adjust the solidified state of polyvinyl alcohol, and it becomes easy to obtain an ink jet recording medium having a good gloss.

  The compounding ratio of borate and boric acid in the treatment liquid is a mass ratio after conversion to anhydride, and is preferably between borate / boric acid = 1/4 to 2/1. When the above blending ratio is less than 1/4, the proportion of boric acid is excessively large and the polyvinyl alcohol in the ink receiving layer is insufficiently solidified, and the soft-coagulated ink receiving layer adheres to the roll to which the treatment liquid is applied. In some cases, an ink receiving layer in a good wet state cannot be obtained. On the other hand, when the blending ratio exceeds 2/1, the polyvinyl alcohol in the ink receiving layer is too hard and solidified, and it is difficult to copy the glossy surface of the mirror drum surface, and it may be difficult to obtain a good glossy surface.

  Examples of the borate used in the present invention include borax, orthoborate, diborate, metaborate, pentaborate, and octaborate. In addition, although borate is not specifically limited to these, From a viewpoint of cost, availability, etc., it is preferable to use borax. The concentration of borate and boric acid in the treatment liquid can be adjusted as necessary, but the total concentration of borate and boric acid in the treatment liquid is in the range of 1 to 8% by mass in terms of anhydride. It is preferable. If the concentration of borate and boric acid, especially the concentration of borate is too high, the solidification of polyvinyl alcohol becomes too strong, and the glossiness of blank paper tends to decrease. On the other hand, when the concentration is high, boric acid is likely to be precipitated in the treatment liquid, so that the stability of the treatment liquid is deteriorated.

Treatment liquids include pigment dispersants, water retention agents, thickeners, antifoaming agents, preservatives, colorants, water resistance agents, wetting agents, fluorescent dyes, UV absorbers, cationic polymer electrolytes, etc. Can be added as appropriate.
The method for applying the treatment liquid to the ink receiving layer is not particularly limited, and may be appropriately selected from known methods (for example, roll method, spray method, curtain method, etc.).
Further, a release agent may be added to the ink receiving layer coating liquid and the treatment liquid in order to facilitate the peeling of the ink receiving layer from the mirror drum. Here, the melting point of the release agent is preferably 90 to 150 ° C, and particularly preferably 95 to 120 ° C. In the above range, since the melting point of the release agent is substantially equal to the metal surface temperature of the mirror finish, the release ability of the release agent is maximized.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples. “Part” and “%” represent “part by mass” and “% by mass”, respectively, unless otherwise specified.

(Manufacture of support)
A pulp consisting of 100 parts of hardwood bleached kraft pulp (L-BKP) having a beating degree of 285 ml, 4 parts of titanium oxide, 0.4 parts of cationic starch (Kate 304L: product name manufactured by NSC Japan), 1.0 parts of aluminum sulfate Part, 0.1 part of a synthetic sizing agent, and 0.02 part of a yield improver were added to prepare a pulp slurry, and the pulp slurry was subjected to paper making using a paper machine to obtain a support.

(Formation of under layer)
Starch is coated on both sides of the support by a gate roll device so that the dry coating amount per side is 1.5 g / m ^2, and the following coating solution A is applied on one side by a blade method. Was applied so that the dry coating amount was 7 g / m ² to form an under layer (basis weight of this coated paper: 180 g / m ² ).
Coating liquid A: 100 parts of synthetic silica (Fine Seal X-37B: Tokuyama Corporation product name), 0.75 parts of D-sorbitol (Sorbit D-70: product name of Towa Kasei Kogyo Co., Ltd.), SB latex ( LX438C: Sumitomo Chemical Co., Ltd. product name) 5 parts, polyvinyl alcohol (PVA117: Kuraray Co., Ltd. product name) 20 parts, sizing agent (Polymarlon 360: Arakawa Chemical Industry Co., Ltd. product name) 5 parts A coating solution having a solid content concentration of 20% was prepared.

(Formation of ink receiving layer)
On the under layer of the coated paper, the following coating liquid B is applied with a roll coater so that the dry coating amount is 20 g / m 2 to form an ink receiving layer, and while the layer is in a wet state, This layer is solidified using the following coagulation liquid C, and then this layer is pressed against the surface of a mirror drum heated to 105 ° C. via a press roll for 20 seconds to copy the mirror surface, and the basis weight is 200 g / m ² . An ink jet recording medium was obtained.
Coating liquid B: Silica (Silojet 703C: Grace Japan Co., Ltd. product name, average particle size 330 nm) 40 parts, high-purity alumina (AKP-G015: Sumitomo Chemical Co., Ltd. product name, average particle size 100 nm) 30 parts), 30 parts of high-purity alumina (UA5605: product name of Showa Denko KK, average particle size 2.8 μm), 13 parts of polyvinyl alcohol (PVA224: product name of Kuraray Co., Ltd.) as a binder, and antifoaming agent 0.2 part was mix | blended and the coating liquid with a solid content concentration of 28% was prepared.
Coagulating liquid C: 4 parts of borax (anhydrous equivalent), 4 parts of boric acid, and 0.25 part of release agent (FL-48C: product name of Toho Chemical Industry Co., Ltd.) were blended, and the solid content concentration was 4.7%. A coagulation solution was prepared.

  An ink jet recording medium was obtained in the same manner as in Example 1 except that in the coating liquid A, the amount of D-sorbitol (Sorbit D-70) was 2 parts.

  An ink jet recording medium was obtained in the same manner as in Example 1 except that in the coating liquid A, the amount of D-sorbitol (Sorbit D-70) was 4 parts.

  In the coating liquid A, instead of the synthetic silica (X-37B) as a pigment, synthetic silica (X-37B) and synthetic silica (Mizukasil P-50: product name of Mizusawa Chemical Co., Ltd.) An ink jet recording medium was obtained in the same manner as in Example 1 except that 100 parts of the 50:50 mixture was blended.

  In the coating liquid A, instead of the synthetic silica (X-37B) as a pigment, synthetic silica (X-37B) and synthetic silica (Mizukasil P-50: product name of Mizusawa Chemical Co., Ltd.) An ink jet recording medium was obtained in the same manner as in Example 2 except that 100 parts of the 50:50 mixture was blended.

  In the coating liquid A, instead of the synthetic silica (X-37B) as a pigment, synthetic silica (X-37B) and synthetic silica (Mizukasil P-50: product name of Mizusawa Chemical Co., Ltd.) An ink jet recording medium was obtained in the same manner as in Example 3 except that 100 parts of the 50:50 mixture was blended.

  Example 1 except that 100 parts of synthetic silica (Mizukasil P-50: product name of Mizusawa Chemical Co., Ltd.) was blended as a pigment in the coating liquid A instead of the synthetic silica (X-37B). In the same manner, an ink jet recording medium was obtained.

  Example 2 except that 100 parts of synthetic silica (Mizukasil P-50: product name of Mizusawa Chemical Co., Ltd.) was blended as a pigment in the coating liquid A instead of the synthetic silica (X-37B). In the same manner, an ink jet recording medium was obtained.

  Example 3 except that 100 parts of synthetic silica (Mizukasil P-50: product name of Mizusawa Chemical Co., Ltd.) was blended as a pigment in the coating liquid A instead of the synthetic silica (X-37B). In the same manner, an ink jet recording medium was obtained.

  An inkjet recording medium was obtained in exactly the same manner as in Example 1 except that in the coating liquid A, the amount of D-sorbitol (Sorbit D-70) was 0.2 part.

  In the coating liquid A, an ink jet recording medium was prepared in the same manner as in Example 1, except that 0.75 parts of xylitol (Xylit: product name of Towa Kasei Kogyo Co., Ltd.) was used instead of D-sorbitol. Obtained.

  Except for blending 0.75 parts of calcium carbonate composite silica (FMT-IJ511: product name of PMMA Tech Co., Ltd.) in place of the synthetic silica (X37B) in the coating liquid A, exactly the same as Example 1. Thus, an ink jet recording medium was obtained.

<Comparative Example 1>
An ink jet recording medium was obtained in the same manner as in Example 1 except that D-sorbitol (Sorbit D-70) was not blended in the coating liquid A.

<Comparative example 2>
An ink jet recording medium was obtained in the same manner as in Example 4 except that D-sorbitol (Sorbit D-70) was not blended in the coating liquid A.

<Comparative Example 3>
An inkjet recording medium was obtained in the same manner as in Example 7 except that D-sorbitol (Sorbit D-70) was not blended in the coating liquid A.

<Comparative Example 4>
An inkjet recording medium was obtained in the same manner as in Example 12 except that D-sorbitol (Sorbit D-70) was not blended in the coating liquid A.

  The oil absorption was in accordance with JIS-K-5101 and the specific surface area was in accordance with the BET method.

<Evaluation>
The ink absorbability, blank paper glossiness, and cutting characteristics of the inkjet recording media obtained in each Example and Comparative Example were evaluated by the following methods.

(1) Ink absorbability Using an inkjet printer (PM-950C: Seiko Epson Corporation product name (using dye ink)), a solid image of red (mixed color of magenta and yellow) and green (mixed color of cyan and yellow) The adjacent pattern was printed, and the ink absorptivity was visually evaluated according to the following criteria for bleeding at the boundary portion. The bleeding (bleed) at the boundary between red and green is black, and a stricter evaluation is possible.
◎: No bleeding at the boundary part ○: Almost no bleeding at the boundary part △: Slight bleeding at the boundary part ×: Remarkable bleeding at the boundary part

(2) Blank paper glossiness Measured according to the method of JIS Z8741, and the 20 ° specular glossiness of the blank paper portion was defined as the blank paper glossiness. When the glossiness of the blank paper is 15% or more, the glossiness is equivalent to that of a silver salt photograph.

(3) Paper dust amount at the time of cutting 400 sheets of A4 size ink-jet recording media are stacked in the same direction, and the moisture in the paper specified in JISP8127 is adjusted to 6.5 ± 0.1% in a constant temperature and humidity chamber in advance. The total amount of paper dust when the sheet was cut four times in the width direction was measured (mg) from the surface opposite to the surface on the ink receiving layer side with a dampening machine (manufactured by Polar, Model No. 115EMC). The blade type of the cutting blade was high speed steel, the blade angle was 21 °, the blade thickness was 12.7 mm, and the clamp pressure was 1.3 t. Of course, the smaller the amount of paper dust, the better. The evaluation was made according to the following criteria according to the amount of paper dust.
A: Less than 5 mg of paper dust (very little paper dust looks)
○: Amount of paper powder 5 to 10 mg (the paper powder is small in appearance)
Δ: Amount of paper dust 10 to 20 mg (slightly more paper dust)
X: Amount of paper dust exceeding 20 mg (the appearance of paper dust is very large

(4) Cut surface cut edge When cutting, see the cut surface cut edge on the non-vertical surface side of the cutting blade (on the other surface side in the cutting blade where one side is flat and the other side is thinner toward the tip) It was evaluated with.
◎: Roughness / fluffing is not observed at all ○: Roughness / fluffing is slightly recognized △: Roughness / fluffing is clearly recognized ×: Roughness / fluffing is remarkably recognized

  The obtained results are shown in Table 1.

  As can be seen from Table 1, in the case of the ink jet recording medium of each example, it was demonstrated that all of the blank paper glossiness, ink absorbability, and cutting characteristics (paper dust amount and cutting cut state) were excellent. On the other hand, in the case of each comparative example in which no sugar alcohol was blended in the under layer, the amount of paper powder at the time of cutting exceeded 20 mg, the cutting edge was not good, and the cutting characteristics were greatly deteriorated.

Claims (6)

One or more under layers containing a pigment, 15 to 60 parts by mass of polyvinyl alcohol, and sorbitol or xylitol with respect to 100 parts by mass of the pigment are provided on at least one side of the support, and the pigment is bonded to the surface of the under layer. An ink jet recording medium comprising at least one ink receiving layer containing an adhesive. 2. The ink jet recording medium according to claim 1, wherein the under layer pigment has an oil absorption of 100 to 300 ml / 100 g. The inkjet recording medium according to claim 1 or 2, wherein the molecular weight of the sorbitol or xylitol is 100 to 400, and the melting point is 70 to 180 ° C. 4. The ink jet recording medium according to claim 1, wherein the pigment of the under layer is synthetic silica. The ink jet recording medium according to claim 1, wherein the ink receiving layer is formed by a cast coating method. The inkjet recording medium according to claim 1, wherein 0.05 to 10 parts by mass of the sorbitol or xylitol is contained in the under layer.