JP2005254635A - Inkjet recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording medium having a good quality in inkjet recording and a texture similar to a silver salt photographic paper. <P>SOLUTION: This inkjet recording medium has at least one ink receptive layer including a pigment and an adhesive provided at one face of a low-density original paper including a chemical material capable of blocking a coupling between fibers of pulp. The reverse face includes a pigment comprising heavy calcium carbonate, an adhesive and a lubricant. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ink jet recording medium used in an ink jet recording system.

  Inkjet recording systems have spread rapidly due to the ease of full-color printing, less printing noise, and the need for development-fixing processing. In recent years, images that are comparable to multicolor printing and color photography by plate-making have been developed. Has been obtained.

  The ink jet recording method is a method in which fine droplets of ink fly and adhere to a recording medium from a nozzle at high speed to record images and characters, and the ink contains a large amount of solvent. Therefore, the recording medium needs to absorb ink promptly. In addition, with the recent spread of computers and digital cameras, images close to silver halide photographs have been required for inkjet recording. Therefore, in order to obtain high color developability, resolution and color reproducibility, an ink jet recording medium having an ink receiving layer provided on the surface has been developed. Furthermore, with expansion of applications, water resistance and light resistance (storability) of printed images are also required for inkjet recording media.

  And when the image quality of inkjet recording is comparable to silver salt photography, it functions as a perfect alternative to silver salt photography, and the user's appearance, feel and handling in development printing labs are similar to silver salt photography. It is required to be. In other words, for the user, when the recording paper is picked up by hand, the paper quality such as the paper stiffness, paper thickness, smoothness (sliding), etc. is closer to the conventional silver salt photographic printing paper. Also in the development printing laboratory, if the paper quality is similar to that of silver salt photographic printing paper, the adjustment of the paper feeding mechanism of the developing device may be the same as that of the prior art.

  In general, photographic paper (RC paper) for silver salt photography has a photosensitive layer or the like formed on the surface of a base paper, and a polyethylene film laminated on the back surface. And as a whole, it is thick and has no waist (small stiffness). For this reason, when normal pulp paper is used thickly and used as the base paper of an ink jet recording medium, there is a problem that the paper becomes stiff and the paper becomes hard, and the tactile sensation differs from that of photographic paper. In particular, since the stiffness is proportional to the cube of the paper thickness, the paper becomes stiff when the thickness of the base paper is the same as that of photographic paper.

  By the way, by making a predetermined organic chemical together with pulp, an ink jet recording paper having a large thickness and low bending stiffness has been developed (for example, see Patent Document 1). Therefore, if the above technique is used, the inkjet recording medium can be thickened without increasing the stiffness.

JP 2002-283712 A

However, when the above technique is used, the problem of paper stiffness can be solved, but it is still insufficient in terms of touch. That is, since the film is laminated, the back surface of the photographic paper is smooth and slippery, but the above technique cannot reproduce such a texture.
Accordingly, an object of the present invention is to provide an ink jet recording medium having good ink jet recording quality and a texture similar to silver salt photographic paper.

  As a result of intensive studies on the above problems, the present inventors have used the following low-density base paper as a base paper, provided an ink receiving layer on one side, and provided a layer containing a predetermined pigment and a lubricant on the opposite side. It was found that can be solved. That is, the ink jet recording medium of the present invention has at least one ink receiving layer containing a pigment and an adhesive on one side of a low-density base paper containing a compound that inhibits the interfiber bonding of pulp, and is overlapped on the opposite side. It has the layer which contains the pigment which consists of quality calcium carbonate, an adhesive agent, and a lubricant. The content of the compound is preferably 0.3 to 1.5 parts by mass per 100 parts by mass of the absolutely dry pulp.

  According to the present invention, an ink jet recording medium having good ink jet recording quality and a texture similar to silver salt photographic printing paper can be obtained. In particular, the smoothness and slipperiness of the back surface are close to those of photographic paper.

  Hereinafter, embodiments of the present invention will be described. The inkjet recording medium of the present invention uses a low-density base paper as a base paper, an ink receiving layer is provided on one side, and a layer containing a predetermined pigment and lubricant is provided on the opposite side.

<Low density base paper>
The low-density base paper can be produced by papermaking a pulp and a compound that inhibits the interfiber bonding of the pulp. The above compound inhibits the bond between pulp fibers to make the paper bulky and flexible, and the obtained low-density base paper has a density in the range of 0.50 to 0.70 g / m ³ . Although it is not clear why the paper becomes bulky and flexible due to the above compound, it is considered that the compound is fixed to the pulp fiber during paper making to hydrophobize the fiber and inhibit hydrogen bonding between the pulp fibers.
Here, the density of the base paper is measured by a method defined in JIS P8118.

<Compound that inhibits interfiber bonding of pulp>
The above compound (hereinafter referred to as “binding inhibitor” as appropriate) may be anything as long as it inhibits binding between fibers of the pulp. For example, a surfactant having a hydrophobic group and a hydrophilic group in the molecule may be mentioned. it can. Specific compounds include higher alcohols or higher fatty acid alkylene oxide adducts and aliphatic polyamidoamine compounds. Examples of commercially available compounds include sulsol VL (trade name, manufactured by BASF: alkylene oxide oligomer), bivolume P liquid (trade name, manufactured by Bayer: fatty acid polyamidoamine), and reactpake (trade name, Sanki Stock) Company-made), KB-08T, KB-08W (trade name, manufactured by Kao Corporation: propylene oxide adduct of higher alcohol), KB-110, KB-115 (trade name, manufactured by Kao Corporation: higher fatty acid and polyvalent Alcohol ester). Two or more of these commercially available compounds may be used in combination.

  The following test can be used as a method for determining whether or not the compound has such characteristics. First, an organic compound to be tested is blended with 0.3 parts by mass with respect to 100 parts by mass of the absolutely dry pulp of the pulp composition to prepare a pulp slurry. Using this slurry, paper was made with a laboratory orientation tester (manufactured by Kumagai Riki Co., Ltd.) at a rotation speed of 900 rpm, pressed in accordance with JIS-8209, dried at 50 ° C. for 1 hour with a blow dryer, and then tested. Get. When the density of the test paper thus obtained is lower than the density of the paper not containing the organic compound, the organic compound can be used in the present invention, but the density reduction amount is preferably 5 to 5%. An organic compound that is about 30%, more preferably 5 to 15%, is preferably used. If the amount of density reduction is less than 5%, the effect of density reduction is small, and if it exceeds 30%, paper strength may be reduced.

  The content of the compound is preferably 0.1 to 5.0 parts by mass and more preferably 0.3 to 1.5 parts by mass with respect to 100 parts by mass of the absolutely dry pulp. When the content of the compound is less than 0.1 parts by mass, the binding of the pulp is not sufficiently inhibited, and a low-density base paper is not obtained. On the other hand, when the content of the compound exceeds 5.0 parts by mass, the general paper quality is changed, for example, the paper strength is reduced or the friction coefficient of the paper is extremely changed.

<Pulp>
The pulp used in the present invention includes chemical pulp (coniferous bleached or unbleached kraft pulp, hardwood bleached or unbleached kraft pulp, etc.), mechanical pulp (ground pulp, thermomechanical pulp, chemisermomechanical pulp, etc.), deinking Pulp and the like can be used alone or mixed at any ratio. The pH during papermaking may be acidic, neutral, or alkaline.

  In addition to the above pulp, a filler may be contained. As the filler, those generally used can be used, and are not particularly limited. For example, clay, calcined clay, diatomaceous earth, talc, kaolin, calcined kaolin, deramikaolin, heavy calcium carbonate, light calcium carbonate, Inorganic fillers such as magnesium carbonate, barium carbonate, titanium dioxide, zinc oxide, silicon oxide, amorphous silica, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, urea-formalin resin, polystyrene resin, phenol Organic fillers such as resins and fine hollow particles can be used alone or in combination of two or more.

  In addition, various conventionally used nonionic or cationic retention agents, freeness improvers, paper strength improvers, internal additive sizing agents, and other internal additives for papermaking are appropriately selected as necessary. May be used. Examples of the internal additive for papermaking include basic aluminum compounds such as sulfate band, aluminum chloride, sodium aluminate, basic aluminum chloride, basic polyaluminum hydroxide, and water-soluble materials such as alumina sol which is easily decomposable in water. Examples thereof include polyvalent metal compounds such as a functional aluminum compound, ferrous sulfate and ferric sulfate, and silica sol. Examples of the various sizing agents include alkyl ketene dimer compounds, alkenyl succinic anhydride compounds, styrene-acrylic compounds, higher fatty acid compounds, petroleum resin sizing agents, and rosin sizing agents.

  Other papermaking aids such as various starches, polyacrylamide, urea resin, melamine resin, epoxy resin, polyamide resin, polyamide, polyamine resin, polyamine, polyethyleneimine, vegetable gum, polyvinyl alcohol, latex, polyethylene oxide, hydrophilic crosslinking Various compounds such as polymer particle dispersions and derivatives or modified products thereof can be used. Furthermore, internal additives for papermaking such as dyes, fluorescent brighteners, pH adjusting agents, antifoaming agents, pitch control agents, slime control agents and the like can be appropriately added depending on the intended use.

  Using the slurry containing the various components described above, paper can be made in the same manner as in a normal papermaking process to produce a low-density base paper. The above compound may be added as it is or an emulsion thereof (so-called internal addition). When adding a compound, it will not specifically limit if it is a place which can be uniformly mixed with a pulp slurry among papermaking facilities, and addition is possible in any place. As the paper machine, a long paper machine, a twin wire machine, a Yankee paper machine, and the like can be used as appropriate. Whether the papermaking method is, for example, acidic paper having a pH of around 4.5, or neutral paper that has an alkaline filler such as calcium carbonate as a main component and has a papermaking pH of about 6 to about 9 Absent.

<Configuration of the opposite surface>
Next, in the ink jet recording medium of the present invention, the configuration of the surface opposite to the ink receiving layer described later will be described. On this surface of the low-density base paper, a layer containing a pigment made of heavy calcium carbonate, an adhesive, and a lubricant is formed.

Examples of the pigment include kaolin, clay, heavy calcium carbonate, light calcium carbonate, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate, colloidal silica, and satin white. However, heavy calcium carbonate is preferred from the viewpoint of glossiness and smoothness because it is close to the texture (resin coating) and touch of the back surface of silver salt photographic printing paper. Heavy calcium carbonate is used in the form of fine particles, but the average particle size is preferably 0.5 to 3 μm. The average particle diameter can be measured by a laser diffraction scattering method.

  Various copolymers of styrene / butadiene, ethylene / vinyl acetate, butadiene / methyl methacrylate, vinyl acetate / butyl acrylate, etc. that have been used for coated papers as adhesives: polyvinyl alcohol, maleic anhydride Synthetic adhesives such as acid copolymers and acrylic acid / methyl methacrylate copolymers: Proteins such as casein, soy protein, and synthetic proteins: oxidized starch, positive starch, urea phosphated starch, hydroxyethyl etherified starch, etc. One or more of these etherified starches and starches such as dextrin: cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose can be selected and used for convenience. These adhesives can be contained in an amount of preferably 5 to 50 parts by mass, more preferably 10 to 30 parts by mass per 100 parts by mass of the pigment.

  As the lubricant, higher fatty acid metal salts such as zinc stearate and calcium stearate: wax calcium phosphates such as paraffin wax, polyethylene wax, carnauba wax, microcrystalline wax and acrylic wax are preferable. In particular, the zinc stearate and calcium stearate are preferable because a sliding effect is produced with a small content. These lubricants can be contained in an amount of preferably 1 to 20 parts by mass, more preferably 3 to 10 parts by mass per 100 parts by mass of the pigment.

The coating liquid containing the pigment, adhesive, and lubricant is, for example, blade coater, air knife coater, roll coater, brush coater, kiss coater, squeeze coater, curtain coater, die coater, bar coater, gravure coater, comma coater, etc. By coating on the opposite surface of the low-density base paper using a known coating machine, a layer containing the pigment, adhesive, and lubricant can be formed. The coating amount is preferably in the range of 3 to 15 g / m ² , and more preferably in the range of 5 to 10 g / m ² .

<Ink receiving layer>
Next, the ink receiving layer formed on one side of the inkjet recording medium (the side facing the opposite side) will be described. The ink receiving layer contains a pigment and an adhesive.

  Examples of the pigment include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, Calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, alumina hydrate, aluminum hydroxide, lipoton, zeolite, magnesium hydroxide, white inorganic pigments, styrene plastic pigment, acrylic plastic pigment, polystyrene Organic pigments such as urea resin and melamine resin can be used.

  Adhesives include starches such as oxidized starch and esterified starch, cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose, polyvinylpyrrolidone, casein, gelatin, soy protein, polyvinyl alcohol or derivatives thereof, polyvinyl alcohol having various saponification degrees or One or more of silanol-modified products, styrene-acrylic resins and derivatives, styrene-butadiene latex, acrylic emulsion, vinyl acetate emulsion, and derivatives thereof can be used.

  The content of the adhesive is preferably 5 to 30 parts by mass and more preferably 5 to 20 parts by mass with respect to 100 parts by mass of the pigment. When the content of the adhesive is less than 5 parts by mass, the strength of the ink receiving layer is lowered, and when it exceeds 30 parts by mass, the ink absorbability of the ink receiving layer is likely to be lowered.

The ink receiving layer is a coating liquid containing the pigment and the adhesive, for example, 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 form by coating on the opposite surface of the said low density base paper using the well-known coating machine of this. Further, the coating amount is preferably in the range of 5 to 30 g / m ² , more preferably in the range of 10 to ²⁰ g / m ² .

  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.

(Production of low-density base paper)
Talc (filler) was blended in 100 parts of LBKP (freezing degree CSF 350 ml) as a pulp content so that the mass was 10% by mass with respect to the mass of pulp. To this pulp slurry, a binding inhibitor (softening agent) KB-08W (trade name, manufactured by Kao Co., Ltd.) was added so as to be 1.2% by mass per pulp to prepare a paper stock. This stock is made with an experimental orientation paper machine (manufactured by Kumagai Riki Co., Ltd.) at a rotation speed of 900 rpm, pressed with an effective press pressure of 0.412 MPa, and dried at 110 ° C. for 3 minutes with a cylinder dryer dryer. A low-density base paper having a basis weight of 150 g / m ² was obtained.
(Coating of ink receiving layer)
The following coating liquid A was coated on one side of the base paper with a bar coater so that the dry coating amount was 12 g / m ² and dried to form an ink receiving layer.
Coating liquid A: 100 parts of synthetic silica (fine seal X-37: trade name manufactured by Tokuyama Co., Ltd.) as a pigment, 5 parts of SB latex (LX438C: trade name of Sumitomo Chemical Co., Ltd.) as an adhesive, adhesion As an agent, 20 parts of polyvinyl alcohol (PVA117: trade name of Kuraray Co., Ltd.) and 5 parts of sizing agent (Polymaron 360: trade name of Arakawa Chemical Industry Co., Ltd.) are mixed to form an aqueous coating with a solid content of 20%. A working solution was prepared.

(Coating of back layer)
On the surface opposite to the ink receiving layer of the above base paper, the following coating liquid B is applied with a bar coater so that the dry coating amount is 6 g / m ² and dried to form a back layer. An ink jet recording medium having a thickness and basis weight shown in 1 was obtained.
Coating liquid B: 100 parts of heavy calcium carbonate as a pigment (FMT-90: trade name manufactured by Phimatech, average particle size 1.5 μm), SB latex as an adhesive (LX-407F46: product manufactured by Nippon Zeon Co., Ltd.) Name) 12 parts, 3 parts by weight of calcium stearate as a lubricant was blended to prepare a coating solution having a solid content of 68%.

  An ink jet recording medium was obtained in exactly the same manner as in Example 1, except that KB-0110 (trade name, manufactured by Kao Corporation) was added as a binding inhibitor instead of KB-08W.

Production of a low density base paper in exactly the same manner as in Example 1 except that Sulsol VL (manufactured by BASF) was added as a binding inhibitor instead of KB-08W to 0.3% by mass per pulp. Went.
Next, an ink receiving layer was formed in exactly the same manner as in Example 1.
Further, a back layer was formed in the same manner as in Example 1 except that the following coating liquid C was used in place of the coating liquid B to obtain an ink jet recording medium.
Coating liquid C: A coating liquid having a solid content concentration of 68% was prepared in exactly the same manner as in Example 1 except that the amount of calcium stearate as a lubricant was 10 parts by mass.

<Comparative Example 1>
A low-density base paper was prepared in the same manner as in Example 1 except that no binding inhibitor was added.
Next, an ink receiving layer was formed in exactly the same manner as in Example 1, but an ink jet recording medium was obtained without forming a back layer.

<Comparative example 2>
A low-density base paper was prepared in exactly the same manner as in Example 3.
Next, an ink receiving layer was formed in exactly the same manner as in Example 1, but an ink jet recording medium was obtained without forming a back layer.

<Comparative Example 3>
A low-density base paper was prepared in exactly the same manner as in Example 3.
Next, an ink receiving layer was formed in the same manner as in Example 1. Further, the back layer was formed in the same manner as in Example 1 except that the following coating liquid D was used instead of the coating liquid B. And an ink jet recording medium was obtained.
Coating liquid D: 100 parts by weight of kaolin (Amazon Plus) as a pigment, 12 parts by weight of SB latex (LX-407F46: manufactured by Nippon Zeon Co., Ltd.) as an adhesive, 3 parts by weight of calcium stearate as a lubricant, solid content concentration A 68% coating solution was prepared.

  The following items were evaluated for the ink jet recording media of each Example and Comparative Example.

(1) Taber stiffness The Taber stiffness was measured according to JIS P-8125 as an index of stiffness of the recording medium. The above Taber stiffness is a bending moment required to bend a test piece when a side of a 38.0 mm wide test piece is gripped to form a cantilever, bend 15 ° at a constant speed, and reach a load length of 50 mm. is there.

(2) 75 ° glossiness of the back surface The 75 ° glossiness of the back surface was measured according to JIS P8142.

(3) Texture 3-1. The stiffness of the paper when the inkjet recording medium was picked up was compared with that of photographic paper (silver salt photographic paper: manufactured by Kodak).
◯: The stiffness is the same as that of the photographic paper. ×: The stiffness is stronger than the photographic paper, and there is no bending. 3-2. Gloss / tactile feel, slipperiness The tactile sensation on the back side of the inkjet recording medium was compared with the back side of photographic paper (silver salt photographic paper: manufactured by Kodak).
○: Glossy appearance on the back side, touch feeling with the hand, slipping touched with the hand are all equivalent to the back side of the photographic paper ×: Glossy appearance on the back side, feeling touched with the hand, slipping touch with the hand Everything is different from the back of photographic paper

(4) Print quality Using a commercially available inkjet printer PM-970C (manufactured by Seiko Epson Corporation), the color density and ink absorbency were evaluated using a predetermined evaluation pattern .
A. Print density (ink color development)
The black (Bk), cyan (C), magenta (M), and yellow (Y) solid pattern print density was measured with a Gretag Macbeth reflection densitometer (trade name: Gretag Macbeth densitometer RD-19I, manufactured by Sakata Inx Corporation). The total of the measured values was taken as the print density.
B. Ink absorption (bleeding)
The blur at the boundary of the solid print portion mixed with red and green was visually evaluated.
○: Color boundary portion clearly separated Δ: Color boundary portion with slight blurring ×: Color blurring portion with large blurring Whether good or bad is judged as follows.
○: Color density (total density 6.50 or more) and ink absorbency are both good ×: Color density and ink absorbency are both poor

  The obtained results are shown in Table 1.

  As is apparent from Table 1, the ink jet recording medium of each example had the same rigidity, gloss on the back surface, and texture as photographic paper, and could ensure the print quality.

  On the other hand, in the case of Comparative Example 1 in which no binding inhibitor was added, the rigidity was very high and the texture was remarkably different from that of photographic paper. In the case of Comparative Example 2 in which no back layer was provided, the texture (glossiness) was significantly different from that of photographic paper. Further, in Comparative Example 3 in which the pigment contained in the back layer was kaolin, the glossiness was too high, and the texture (glossiness) was significantly different from that of photographic paper.

Claims (2)

  One side of a low-density base paper containing a compound that inhibits the interfiber bonding of pulp has one or more ink-receiving layers containing a pigment and an adhesive, and a pigment and an adhesive composed of heavy calcium carbonate on the opposite side An ink jet recording medium comprising a layer containing a lubricant.   2. The ink jet recording medium according to claim 1, wherein the content of the compound is 0.3 to 1.5 parts by mass per 100 parts by mass of the absolutely dry pulp.