JP5167045B2 - Inkjet recording paper - Google Patents

Description

  The present invention relates to an ink jet recording paper in which an ink fixing agent is supplied to the recording paper before printing. More specifically, the present invention relates to an ink jet recording paper that provides both an appearance like coated paper for offset printing and excellent ink jet aptitude.

  Applications for printing using the inkjet method are not limited to terminal PC printers, fax machines, or copiers, but are being put to practical use in the so-called on-demand printing field, which enables various types of small lot printing and variable information printing. The technological progress is remarkable. In recent years, with the improvement of printing speed and image quality, the use of the number of printed copies has been studied even in an area where printing is conventionally performed by offset or gravure printing.

  Since electrophotographic printing is a plateless printing method, it is advantageous to handle variable information. On the other hand, although offset and gravure printing cannot handle variable information, it is suitable for performing high-quality printing in large quantities at low cost. Therefore, in the ink jet system, technological development is being promoted from the viewpoints of printing machines, toners, and recording papers toward higher image quality, higher speed, lower power consumption, and lower costs. In addition, there is a demand for further improvement in quality such as ink fixing property, storage property, color reproducibility, and running property.

  The ink jet method is a method in which fine ink droplets are ejected onto the surface of an object to be transferred to form an image. Recent technological advances are remarkable, the image quality is extremely high, and the weather resistance, which has been a weak point, has been greatly improved by the appearance of pigment-type inks. However, compared to offset printing and gravure printing, the printing speed is slow to obtain high image quality, and the coated paper that has a high-class feel and high-quality finish has improved silica absorption and alumina to improve ink absorption. Although the fine pigments of the system are often used, there is a problem that they are expensive.

  Therefore, in the area of on-demand printing, when considering variable information, satisfying conditions such as high image quality and high speed, one solution is to use a chemical that improves ink fixing properties in the printer. I figured it out. Specifically, such a fixing agent is ejected simultaneously with ink for the purpose of coloring (see, for example, Patent Document 1), ejected before ink is landed (see, for example, Patent Document 1), A method of mixing with ink (for example, refer to Patent Documents 1 and 2), a method of discharging after landing of an ink (for example, refer to Patent Document 3), and a method of drying after mixing of a fixing agent and ink (for example, Patent Document 4) See). Further, as a principle for fixing the ink, an anionic or cationic interaction between ions (for example, see Patent Documents 1, 2, 3, and 4), a polymer overcoat (for example, Patent Document 5, 6), and an interlayer material for fixing ink, so-called pigments (for example, see Patent Document 7).

As such technology develops, there is a demand for inkjet recording paper that can provide both an appearance like coated paper for offset printing, which has a high-class feel, and excellent inkjet suitability for applications such as books, calendars, and brochures. . Examples of the recording medium include plain paper (see, for example, Patent Documents 1, 4, 6, 7, and 9), coated paper for commercial printing such as offset printing (for example, see Patent Documents 4, 8, 9, and 10), and alumina. Or description examples, such as a medium (for example, refer to patent documents 11 and 12) which applied silica, a non-porous plastic sheet (for example, refer to patent document 13), a cloth (for example, refer to patent document 14), are mentioned. However, it does not particularly satisfy the performance as an ink jet recording paper in which an ink fixing agent is supplied to the recording paper before printing.
Japanese Patent Laid-Open No. 10-016376 Japanese Patent No. 397794 JP 2002-029141 A JP 2003-048317 A Japanese Patent No. 4065130 JP 2005-297567 A Japanese Patent Application Laid-Open No. 07-096603 JP 2004-130799 A JP 2008-105422 A JP 2004-181955 A JP 2002-001943 A JP 2005-001387 A JP 2003-025709 A JP 2004-143462 A

  An object of the present invention is to provide an ink jet recording paper which has an appearance similar to that of a coated paper for offset printing and has excellent ink jet aptitude in an ink jet printing in which an ink fixing agent is supplied to the recording paper before printing. There is.

  As a result of intensive studies to solve the above problems, the present inventors have invented the following ink jet recording paper.

That is, in an ink jet recording paper in which an ink fixing agent is supplied to the recording paper before printing, the recording paper is provided with at least one coating layer mainly composed of a pigment and a binder on at least one side of a sheet-like substrate. The pigments are heavy calcium carbonate, light calcium carbonate and kaolin, and the total of void volume in the range of pore diameter of 0.002 to 100 μm by the mercury intrusion method after the coating layer is applied and dried Is an ink-jet recording paper, characterized in that it is 250 to 600 mL / m ² .

  The recording paper of the present invention has an appearance similar to that of coated paper for offset printing as an ink jet for supplying an ink fixing agent to the recording paper before printing, and exhibits excellent ink jet aptitude.

  Hereinafter, the ink jet recording paper of the present invention will be described in detail.

  The present inventor examined a technique for showing an appearance similar to that of coated paper for offset printing and exhibiting excellent ink jet aptitude in ink jet printing in which an ink fixing agent is supplied to a recording paper before printing. As a result, it was found that stable ink fixability is exhibited by setting the void volume of the coating layer that receives the ink fixing agent within an appropriate range.

The ink jet recording paper of the present invention is directed to an ink jet system in which an ink fixing agent is supplied to the recording paper before printing, and is a coating mainly composed of a pigment and a binder on at least one side of a sheet-like substrate. A recording paper provided with at least one layer, wherein the total void volume in the range of pore diameters of 0.002 to 100 μm by a mercury intrusion method is 250 to 600 mL / m ² . When the void volume is less than 250 mL / m ² , the capillary may be developed, but the capacity itself is insufficient, so that the ink fixing agent cannot be received sufficiently, which causes ink bleeding. Further, when the void volume exceeds 600 mL / m ² , the capacity of the pore diameter effective for absorbing the ink fixing agent is excessively large, so that the ink fixing agent is absorbed rapidly and in large quantities, and the ink fixing agent is It penetrates to the deep layer of the coating layer or the sheet-like substrate, and the interaction with the ink becomes insufficient. As a result, it causes ink bleeding and has an adverse effect particularly on the image reproducibility of fine lines.

The pigment here is a pigment component for providing a coating layer with predetermined whiteness, glossiness, and fine voids. The coating amount is 5 to 30 g / m ² per side and may be a single layer or multiple layers.

  Examples of the base material of the recording paper for inkjet used in the present invention include plant fibers such as wood pulp, cotton, hemp, bamboo, sugarcane, corn and kenaf, animal fibers such as wool and silk, cellulose such as rayon, cupra and lyocell. Recycled fibers, semi-synthetic fibers such as acetate, polyamide fibers, polyester fibers, polyacrylonitrile fibers, polyvinyl alcohol fibers, polypropylene fibers, polyvinylidene chloride fibers, polyurethane fibers, and other chemical fibers, glass fibers, metals A sheet made of inorganic fibers such as fibers and carbon fibers is used.

  These fibers include heavy calcium carbonate, light calcium carbonate, kaolin, talc, clay, titanium dioxide, aluminum hydroxide and other fillers, binders, sizing agents, fixing agents, retention agents, paper strength enhancers, etc. These various compounding agents are suitably blended according to each step and each material. Furthermore, a resin coat layer may be provided on these fiber sheets.

  In the case of using a fiber sheet-like base material, as a manufacturing method for making each fiber into a sheet, a general paper making process, a wet method, a dry method, a chemical bond, a thermal bond, a spun bond, a spun lace, a water jet, a melt blow, One or more are appropriately selected from each process such as needle punching, stitch blowing, flash spinning, and tow opening.

The sheet-like base material is applied with various surface treatments such as surface size and calendar treatment in order to obtain the required density, smoothness, and air permeability. It adjusts so that the sum total of the void | capacitance volume in the range of the pore diameter 0.002-100 micrometers by a mercury intrusion method may be 250-600 mL / m < ² >.

In the present invention, the pigment used for the coating layer on the sheet-like substrate includes, in addition to heavy calcium carbonate, light calcium carbonate, kaolin, purified natural mineral pigments such as talc, calcium carbonate and other hydrophilic organics. Examples include composite synthetic pigments with compounds, satin white, lithopone, titanium dioxide, silica, alumina, aluminum hydroxide, zinc oxide, magnesium carbonate, and organic pigments. Preferably, a fine particle or needle-like particle having an average particle size of 0.5 μm or less as a pigment is contained in the coating layer in a total of 50 parts by mass or more, and then calendered after coating and drying. The total void volume in the range of pore diameters of 0.002 to 100 μm according to the mercury intrusion method of the present invention, which works effectively for absorption of the ink fixing agent by adjusting the nip width, the linear pressure, and the temperature is 250 to 600 mL. / M ² is controlled.

As binders used in the coating layer, various copolymer latexes such as styrene-butadiene, acrylic, polyvinyl acetate, ethylene-vinyl acetate, polyvinyl alcohol, modified polyvinyl alcohol, sodium polyacrylate, polyethylene oxide, poly Examples thereof include water-soluble compounds such as acrylamide, urea or melamine / formalin resin, polyethyleneimine, and polyamidepolyamine / epichlorohydrin. Furthermore, starch purified from natural plants, hydroxyethylated starch, oxidized starch, etherified starch, phosphate esterified starch, enzyme-modified starch, cold water soluble starch obtained by flash drying them, dextrin, mannan, chitosan, Examples thereof include natural polysaccharides such as arabinogalactan, glycogen, inulin, pectin, hyaluronic acid, carboxymethylcellulose, hydroxyethylcellulose, oligomers thereof, and modified products thereof. Examples thereof include natural proteins such as casein, gelatin, soybean protein and collagen, and modified products thereof, and synthetic polymers and oligomers such as polylactic acid and peptides. These can be used alone or in combination. In order to obtain the ink jet recording paper of the present invention, considering the ratio of the pigment and the binder, the total void volume in the range of pore diameter of 0.002 to 100 μm by the mercury intrusion method is 250 to 250 by combining the sheet-like base material. It is adjusted to be 600 mL / m ² .

  The thickener used in the coating layer includes water-soluble polymers such as carboxymethylcellulose, sodium alginate, methylcellulose, hydroxyethylcellulose, casein, sodium polyacrylate, polyacrylate, and styrene maleic anhydride copolymer. And synthetic polymers such as silicates and inorganic polymers such as silicates.

  In addition, various auxiliary agents that are usually used such as a dispersant, an antifoaming agent, a water-proofing agent, and a coloring agent, and those obtained by cationizing these auxiliary agents are suitably used as necessary.

  In the present invention, the coating method is not particularly limited, and various film transfer coaters such as a size press having a puddle, a metering size press, a gate roll, and a shim sizer, an air knife coater, a rod coater, a blade coater, Each system such as curtain coater, spray coater, cast coater is used as appropriate.

Furthermore, in order to obtain the required density, smoothness, air permeability, and appearance, the manufactured recording paper in a series of operations is subjected to various finishing treatments such as calendering as necessary and carefully controlled. Thus, the total void volume in the range of pore diameters of 0.002 to 100 μm according to the mercury intrusion method of the present invention can be adjusted to 250 to 600 mL / m ² . In order to obtain the void volume of the present invention, it is preferable to use a soft calender device comprising a metal roll and an elastic roll with the coating layer surface nipped on the metal roll.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. Further, “parts” and “%” shown in the examples indicate parts by mass and mass% unless otherwise specified.

(Example 1) to (Example 4) and (Comparative Example 1) to (Comparative Example 3)
An ink jet recording paper was prepared according to the following contents.

<Preparation of pulp slurry>
LBKP (freeness 400 mlcsf) 70 parts NBKP (freeness 480 mlcsf) 30 parts Filler (indicated by ash content in base paper) 8 parts Commercial cationized starch 1.0 part Commercial cationic polyacrylamide retention improver 0.03 part The freeness was adjusted, the freeness was adjusted, the internal chemicals were prepared with the above composition, and the base paper was made with a long paper machine at a basis weight of 60.0 g / m ² .

<Preparation of sheet-like substrate>
To this base paper, 0.8 g / m ² of oxidized starch was adhered on both sides by a size press to prepare a sheet-like substrate.

<Preparation of coating solution>

Pigment The number of blending parts is listed in Table 1. Commercial styrene butadiene latex binder (average particle size 180 nm) 12 parts Commercial phosphoric esterified corn starch 2 parts Commercial calcium stearate lubricant 0.3 parts Commercial carboxymethyl cellulose thickener (CMC) 0.1 parts The above was blended in solid mass parts, dispersed and stirred, adjusted to pH 9.6 with sodium hydroxide, and the solid content concentration of the coating liquid was adjusted to 60 mass% with water.

These coating solutions were applied with a blade coater, dried, and subjected to soft calendering. Calendering adjusted the linear pressure to obtain the intended void volume. The linear pressure is shown in Table 1. The coating amount was 15 g / m ² .

  The ink jet recording papers obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were measured by the following measuring methods, and the evaluation results are listed in Table 1.

<Void volume>
Measurement of pore diameter and void volume by mercury porosimetry was obtained using Autopore III9420 manufactured by MICROMERITICS. The pore measurement range was about 0.0018 to 100 μm, and the total void volume was in the range of pore diameters of 0.002 to 100 μm.

The image quality after inkjet printing was evaluated using “CM8060” manufactured by Hewlett-Packard Co. as an inkjet printer that supplies an ink fixing agent to recording paper before printing.
<Thin lines blur>
About the sheet | seat after inkjet printing, the thin line of 0.25 points was printed for each color of cyan, magenta, yellow, and black, and the boundary bleeding was visually determined. The quality criteria are as follows.
A: The characteristics are very good.
○: Good.
(Triangle | delta): The level which is satisfactory practically.
X: Indicates an unusable level due to practical problems.

<Evaluation results>
In Comparative Examples 1 and 2 in which the void volume was less than the range of claim 1, the capacity for receiving the ink fixing agent was insufficient, so that the ink fixing agent could not be received sufficiently, and thin line ink bleeding occurred . On the other hand , Examples 1 to 4 having an appropriate void volume were excellent in reproducibility of fine lines, and almost no ink bleeding occurred.

  In the ink jet printing in which the ink fixing agent is supplied to the recording paper before printing, it can be used as a recording paper having both the appearance like coated paper for offset printing and excellent ink jet aptitude.

  The ink jet recording paper in the present invention is not limited to use as an ink jet recording paper, but can also be used in other printing methods such as wet and dry electrophotography, offset printing, gravure printing, and thermal transfer.

Claims (1)

In the ink jet recording paper of format supplied to the recording paper ink fixing agent before printing, a recording sheet provided at least one layer of at least the coating layer consisting mainly of a pigment and a binder on one side of the sheet-like substrate, the pigment Is heavy calcium carbonate, light calcium carbonate, and kaolin, and after the coating layer is coated and dried, it is soft calendered and the total void volume in the range of pore diameters of 0.002 to 100 μm by the mercury intrusion method is 250. Inkjet recording paper, characterized in that it is ˜600 mL / m ² .