JP2005212263A - Ink jet recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mat tone inkjet recording medium excellent in dye ink color developing properties, pigment ink color developing properties and dye ink absorbing properties. <P>SOLUTION: The outermost coating layer provided on a substrate is an ink receiving layer comprising a pigment and a hydrophilic binder as main components, and pigments incorporated in the ink receiving layer mainly comprise a synthetic non-crystalline silica and a colloidal silica, and the mass compounding ratio thereof is the synthetic non-crystalline silica:the colloidal silica=98;2-60:40. It is preferable that the primary particle diameter of the colloidal silica is 5-40 nm, and the shape is a chain-like shape or an associated shape. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a recording medium that performs printing by an ink jet recording method, and more particularly to a matte ink jet recording medium that can obtain a good recorded image using either dye ink or pigment ink.

  As an ink coloring material in an ink jet recording method, water-soluble dyes have been used so far for reasons such as good image sharpness and ink ejection stability, and less head clogging. However, there were difficulties in storage stability including light resistance and water resistance. On the other hand, in recent years, pigment inks using pigments as coloring materials are becoming popular due to the development of pigment dispersion technology. When an image is recorded with pigment ink, the storage stability is good, but when printing is performed on a conventional inkjet recording paper designed for dye ink, the color developability of the image is inferior, and the color material (pigment) is recorded on the recording paper. There was a problem of missing from the surface. In order to solve this problem, Patent Document 1 reports several recording media that can obtain a good recorded image regardless of whether dye ink or pigment ink is used. For example, the support contains amorphous silica having an average particle size of 5 to 20 μm and polyvinyl alcohol having a saponification degree of 90.0 to 97.0 mol% and a polymerization degree of 1000 to 3500, and the compositional weight ratio of the amorphous silica to the polyvinyl alcohol is A method of providing an ink receiving layer that is 100/100 to 100/20 is disclosed.

  Patent Document 2 discloses an inkjet recording medium for pigment ink having a 20-degree specular gloss on the surface of the ink receiving layer of 2 to 18% and an image definition gloss of 20 or less. Patent Documents 3 and 4 disclose that an ink jet recording sheet excellent in high glossiness is obtained by using colloidal silica or fine silica particles having a very small particle diameter.

  On the other hand, the recording medium of the ink jet recording system is roughly classified into a plain paper type that has a texture similar to so-called high-quality paper and PPC paper, and a coated paper type that clearly has an ink receiving layer. Further, the coated paper type recording medium is roughly classified into a gloss type having gloss in the ink receiving layer and a mat type having no gloss. In the mat type ink jet recording medium, the surface of the ink receiving layer is relatively rough. Therefore, the color material (pigment) in the pigment ink is easily fixed on the surface of the recording paper, but the color developability of the image is very poor.

JP 2003-94794 A JP 2002-321448 A Japanese Patent Laid-Open No. 9-263039 JP 2000-85242 A

However, in the above-described conventional technology, an ink jet recording sheet having a high recorded image density, a matte surface, and good fixability of the pigment ink has been obtained even if either dye ink or pigment ink is used. Absent. In the ink jet recording sheet described in Patent Document 1, color developability is not satisfactory in any case where printing is performed using dye ink or pigment ink. In Patent Document 2, in order to obtain a recording medium having good color development and fixability of the pigment ink, a pigment having an average particle diameter of 1 μm or less is used to adjust the glossiness and surface roughness of the ink receiving layer. There was a problem with color development and absorbability when printed with.
The ink jet recording sheets obtained in Patent Document 3 and Patent Document 4 have a high glossiness on the surface and are not matte, and therefore have poor fixability of pigment ink.

  Accordingly, the present invention provides a mat-like ink jet recording medium having an ink receiving layer on the surface of a support, which is excellent in dye ink coloring property, pigment ink coloring property and dye ink absorbing property. The purpose is to provide.

  The object of the present invention is to provide an ink jet recording medium having one or more coating layers on a support, wherein the outermost coating layer is an ink receiving layer mainly composed of a pigment and a hydrophilic binder. The pigment contained in the ink receiving layer is mainly synthetic amorphous silica and colloidal silica, and the mass blending ratio thereof is synthetic amorphous silica: colloidal silica = 98: 2 to 60:40, and the ink receiving layer surface. The degree of specular gloss measured at 75 degrees was 15% or less.

  The colloidal silica has a primary particle size of 5 to 40 nm, preferably a chain or an association shape, and the synthetic amorphous silica has a secondary particle size of 5 to 20 μm, The oil absorption is preferably 180 to 400 ml / 100 g.

  In the present invention, it is possible to obtain an ink jet recording medium capable of improving the color developability of dye ink and pigment ink without impairing ink absorption. In addition, since the surface of the ink receiving layer is matte, the fixability of pigment ink is good

  The ink jet recording medium in the present invention preferably comprises a support having a sheet shape and a coating layer formed thereon. The support of the ink jet recording medium of the present invention is not particularly limited, and is a sheet-like material such as paper mainly made of wood fiber (pulp), plastics such as polyethylene, or non-woven fabric mainly made of wood fiber or synthetic fiber. In the case of paper, it may be added or not added with an internal sizing agent, and may or may not contain a filler. In the present invention, it is desirable to use paper having excellent ink absorbability as the support.

  Wood pulp that constitutes the paper support, chemical pulps such as LBKP and NBKP, mechanical pulps such as GP, PGW, RMP, TMP, CTMP, CMP, and CGP, and pulps such as waste paper pulp such as DIP are used alone or in combination. It is possible to use. The paper support is mixed with various additives such as fillers, binders, sizing agents, fixing agents, yield improvers, paper strength enhancers, etc., which are conventionally known, in the above wood pulp. It can be obtained by drying after forming a web with various paper machines such as a paper machine and a twin wire paper machine.

  In the present invention, among the coating layers formed on the support, the outermost layer is an ink receiving layer mainly composed of a pigment and a hydrophilic binder, but the surface of the ink receiving layer has a 75-degree specular gloss. The degree needs to be 15% or less. When the 75 ° specular glossiness exceeds 15%, the matte ink jet recording medium is not obtained, and the color material (pigment) in the pigment ink is difficult to be fixed on the recording paper surface.

  In the present invention, colloidal silica and synthetic amorphous silica are mainly used as the pigment of the ink receiving layer, but other commonly used pigments (for example, calcium carbonate, kaolin, alumina, etc. within a range not impairing the effects of the invention). It is also possible to mix plastic pigments, etc.). However, pigments other than colloidal silica and synthetic amorphous silica are preferably blended in the ink-receiving layer pigment at a ratio of less than 10% by mass, and more preferably at a ratio of less than 5% by mass. .

  The colloidal silica used in the present invention is a synthetic silica having a primary particle diameter of about several nanometers to 100 nm synthesized by a wet method, and includes a case where the non-spherical secondary particles are aggregated. Further, colloidal silica includes an aqueous dispersion in which core / shell structure particles in which an acrylic polymer is bonded to the surface of spherical colloidal silica particles are dispersed in an aqueous solvent. The colloidal silica used this time preferably has a primary particle size of 5 to 40 nm. More preferably, the shape is a chain or an association. Spherical (non-secondary aggregated) and pearl necklace-shaped colloidal silica is not preferred because the color developability of the dye ink tends to be lower than that of chain-like and associative colloidal silica. The shape of the colloidal silica described above can be observed with an electron microscope (such as SEM). The primary particle size of colloidal silica can be measured by the BET method and the secondary particle size can be measured by the dynamic light scattering method.

  Here, the chain colloidal silica is a shape in which several to a dozen or more primary particles are connected in a chain shape, and the ratio of the secondary particles to the primary particles is larger than 2.5. The shape is a combination of several primary particles, the ratio of secondary particles to primary particles is 1.5 to 2.5, and pearl necklace-like colloidal silica is a few to a dozen primary particles agglomerated like a necklace. Colloidal silica.

  The ratio of synthetic amorphous silica to colloidal silica in the ink receiving layer is preferably 98: 2 to 60:40 from the viewpoint of improving color developability. In particular, the pigment ink color developability tends to improve as the colloidal silica content increases, and is preferably 80:20 to 70:30.

  The synthetic amorphous silica contained in the ink receiving layer of the present invention is formed by a neutralization reaction between sodium silicate and sulfuric acid, and can be divided into various properties as a functional filler depending on the production method. The oil absorption specified by K-5101 is desirably 180 ml / 100 g or more. If it is less than 180 ml / 100 g, the color developability and ink absorbability when printing with dye ink is deteriorated. On the other hand, if it exceeds 400 ml / 100 g, the hardness of the pigment is lowered to form an extremely soft pigment, which makes it difficult to write with a pencil or the like, so 200 to 350 ml / 100 g is preferred.

  Furthermore, the average secondary particle diameter of the synthetic amorphous silica is preferably 5 to 20 μm, more preferably 7 to 12 μm. When the average secondary particle diameter is less than 5 μm, there are problems that the image clarity with the dye ink is inferior and the surface strength of the coating layer is lowered. On the other hand, if the average secondary particle size is larger than 20 μm, it is not preferable because the image sharpness and ink absorbability deteriorate. The average secondary particle diameter of the synthetic amorphous silica described above can be measured using a master sizer manufactured by Malvern.

  The ink receiving layer of the present invention contains a hydrophilic binder in order to maintain the properties as a coating film. Examples of the hydrophilic binder include polyvinyl alcohol and modified products thereof, oxidized starch, etherified starch, casein, gelatin, soy protein, carboxymethyl cellulose, SB latex, NB latex, acrylic latex, vinyl acetate polymer latex, ethylene acetate Vinyl latex, polyurethane, unsaturated polyester resin, etc. can be used. In this invention, although at least 1 sort (s) of these hydrophilic binders can be used, it is preferable that the compounding part number is 5-60 weight part with respect to 100 weight part of above-described pigments. When the number of blended parts of the binder is small, the surface strength is insufficient, and when it is too large, the ink absorbability is insufficient.

  In the present invention, the ink receiving layer preferably contains a cationic water-soluble resin. Examples of the cationic water-soluble resin used in the present invention include secondary amines, tertiary amines, and quaternary ammonium salts such as polyethyleneimine salts, dimethylamine epihalohydrin condensates, polyvinylamine salts, polyallylamine salts, and polydimethylaminoethyl. Examples thereof include methacrylate quaternary salts, polydiallyldimethylammonium salts, diallylamine acrylamide copolymer salts, and quaternary ammonium salts of polystyrene. Among them, a dimethylamine epihalohydrin condensate having excellent printing quality for both dye ink and pigment ink and particularly high printing density and water resistance is preferable. Two or more of these cationic resins can be used in combination.

  These cationic water-soluble resins have an action of capturing the pigment, which is a color material in the pigment ink, by dispersing it in a solvent with a dispersant and charging the surface negatively. Accordingly, the pigment ink remains in the vicinity of the surface of the ink receiving layer, and the friction resistance is improved. Similarly, with respect to the dye ink, the negatively charged dye is captured by the cationic water-soluble resin in the ink receiving layer, and the storage stability, particularly water resistance, is improved.

  In addition, sizing agent, pigment dispersant, thickener, fluidity improver, surfactant, antifoaming agent, antifoaming agent, mold release agent, foaming agent, penetrating agent, coloring dye on support or ink receiving layer , Fluorescent whitening agents, ultraviolet absorbers, antioxidants, antiseptics, antibacterial agents, water resistance agents, wet paper strength enhancers, dry paper strength enhancers, water retention agents, and the like can be appropriately contained as necessary. .

  In the present invention, the total number and configuration of the coating layer and the ink receiving layer provided on the support are not particularly limited. Further, the coating layer and the ink receiving layer may be provided on one side or both sides of the support.

  In the present invention, when the ink receiving layer is provided on one side of the support, a coating layer may be provided on the surface of the support opposite to the ink receiving layer for the purpose of curling correction or improving transportability. It is. Furthermore, it is also possible to provide one or more coating layers between the ink receiving layer and the support. In this case, the composition of the layer is not particularly specified, but a layer containing a pigment, a hydrophilic binder, and a cationic resin as main components is preferable.

In the present invention, the coating amount (dry coating amount) of the ink receiving layer is preferably 1 to ²⁰ g / m ² . Furthermore, 1-15 g / m < ² > is preferable, More preferably, it is 3-15 g / m < ² >. When the coating amount of the ink receiving layer is less than 1 g / m ² , the pigment ink color development is lowered and the absorbability of the dye ink is lowered, so that the ink jet printing performance is adversely affected.

When a coating layer other than the ink receiving layer is provided on the support, the total coating amount (dry coating amount) of the coating layer (that is, the ink receiving layer and the other coating layers described above) provided on the support. ) Is preferably 20 g / m ² or less, more preferably 15 g / m ² or less. When the coating amount exceeds 20 g / m ² , the adhesive strength between the ink receiving layer and the support becomes a level that cannot be practically used, and peeling of the coating layer from the support, which is called powdering off, occurs. Problems arise.

When one or more coating layers are provided between the ink receiving layer and the support, the total coating amount of the coating layers other than the ink receiving layer is preferably 7 to 19 g / m ² . The coating amount of the time the ink-receiving layer is the top layer is preferably 1~13g / m ^2, more preferably 3 to 10 g / m ^2.

  In order to provide an ink receiving layer and a coating layer other than the ink receiving layer on the support surface, various blade coaters, roll coaters, air knife coaters, bar coaters, gate roll coaters, curtain coaters, which are general coating devices, Various apparatuses such as a short dwell coater, a gravure coater, a flexographic gravure coater, and a size press can be used on-machine or off-machine.

  Further, in the present invention, after the ink receiving layer is applied, the ink receiving layer can be surface-treated with a calendar device such as a machine calendar, a super calendar, or a soft calendar.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. Further, “parts” and “%” shown in the examples indicate parts by mass and mass% unless otherwise specified.
<Example 1>
A pulp prepared by mixing and beating 90% hardwood bleached kraft pulp and 10% softwood bleached kraft pulp and adjusting the freeness to 350 ml, 4 parts cationized starch, 0.3 parts anionized polyacrylamide, and alkyl ketene dimer 0.5 parts of the emulsion was added, and a web was formed using a long paper machine. After performing a three-stage wet press, the drying part performs a two-stage tension press and drying, and then using a size press, a dry weight of 3% of a phosphate esterified starch solution of 5% and polyvinyl alcohol of 0.5% is used. the coating is .6g / ^{m 2,} was produced base paper having a basis weight of 175 g / ^{m 2} after drying machine calendering treatment to.

Under layer amorphous silica (Fine Seal X-12 manufactured by Tokuyama: Average secondary particle diameter 10 [mu] m, oil absorption 240 ml / 100 g) 100 parts Polyvinyl alcohol (PVA-117, manufactured by Kuraray) 25 parts of ethylene-vinyl acetate emulsion (SUMIKAFLEX 401 4 parts styrene butadiene latex (LX438C made by Nippon Zeon) 4 parts styrene acrylic resin (Polymaron 360 made by Arakawa Chemical) 2 parts polydiallyldimethylammonium chloride (PAS-H-10L made by Nittobo) 4 parts defoamer (manufactured by Sumitomo Chemical) SN Deformer 480 manufactured by San Nopco) 0.5 part bluing agent 0.012 part fluorescent dye 0.7 part and diluted water etc. were added appropriately, and the color of the solid content 22% was dried using a bar blade coater. Coating was performed so that the work amount was 10 g / m ² .

Top layer Colloidal silica (PL-2, manufactured by Fuso Chemical Co., Ltd., primary particle size 10-20 nm, secondary particle size 20-80 nm, associated) 2.5, 5, 10, 20, 40 parts Synthetic amorphous silica (Mizukasil P-50, manufactured by Mizusawa Chemical Co., Ltd .: average secondary particle diameter 8.5 μm, oil absorption 170 ml / 100 g) 100 parts polyvinyl alcohol (PVA-117, manufactured by Kuraray) 30 parts antifoaming agent (SN deformer 480 manufactured by San Nopco) 0 A color having a solid content of 22%, to which 5 parts and dilution water were appropriately added, was coated using a bar blade coater so that the coating amount was 10 g / m ² .

<Example 2>
Under layer Amorphous silica (Fine seal X-12, manufactured by Tokuyama) 100 parts Polyvinyl alcohol (PVA-117, manufactured by Kuraray) 25 parts Ethylene vinyl acetate emulsion (Sumikaflex 401, manufactured by Sumitomo Chemical) 4 parts Styrene butadiene latex (LX438C made by Nippon Zeon) 4 parts styrene acrylic resin (Polymaron 360 made by Arakawa Chemical Co., Ltd.) 2 parts polydiallyldimethylammonium chloride (PAS-H-10L made by Nittobo) 4 parts antifoaming agent (SN deformer 480 made by San Nopco) 0.5 Part of a blueing agent 0.012 part Fluorescent dye 0.7 part and diluting water, etc. were added as appropriate, so that a color with a solid content of 22% was applied to a coating amount of 10 g / m ² using a bar blade coater. Coated.

Top layer Colloidal silica (Snowtech OU-P, manufactured by Nissan Chemical Co., Ltd., primary particle size 20-35nm, secondary particle size 40-300nm, chain) 2.5, 5, 10, 20, 40 parts synthesis Amorphous silica (Mizukasil P-50 made by Mizusawa Chemical) 100 parts polyvinyl alcohol (PVA-117, made by Kuraray) 30 parts antifoaming agent (SN deformer 480 made by San Nopco) and dilution water were added as appropriate, A color having a solid content of 22% was applied using a bar blade coater so that the coating amount was 8 g / m ² .

<Comparative Example 1>
A base paper coated with the under layer produced in Example 1 is coated with a color of the following composition not containing colloidal silica as the top layer of Example 1 using a bar blade coater so that the coating amount is 8 g / m ^2. Coated.
・ Combined synthetic amorphous silica (Mizukasil P-50, manufactured by Mizusawa Chemical) 100 parts Polyvinyl alcohol (PVA-117, manufactured by Kuraray) 30 parts Antifoam (SN deformer 480, manufactured by San Nopco) 0.5 parts

<Comparative example 2>
The base paper coated with the under layer produced in Example 1 was coated with a color of the following composition not containing the synthetic amorphous silica of the top layer of Example 1 using a bar blade coater, and the coating amount was 8 g / m ^2. It was coated so that
・ Combination colloidal silica (Snowtech OU-P, manufactured by Nissan Chemical Co., Ltd.) 100 parts Polyvinyl alcohol (PVA-117, manufactured by Kuraray) 30 parts Antifoaming agent (SN deformer 480, manufactured by San Nopco) 0.5 parts

Evaluation Method Each recording medium in the examples and comparative examples was evaluated by the following method. In each item, if the evaluation is Δ or more, it can be put into practical use.
Evaluation item <Color development>
Each solid image was printed for black, cyan, magenta, and yellow and allowed to stand for one day, and then the print density of each image area was measured with a reflection densitometer (MACBEATH RD194I).
Evaluation printer: PM970C (Seiko Epson, dye ink printer), PM4000PX (Seiko Epson, pigment ink printer)
<Ink absorbability>
Each solid image of red and green was printed next to each other, and the degree of bleeding at the boundary portion was subjected to sensory evaluation.
Evaluation printer: PM970C (Seiko Epson, dye ink printer)
○: The boundary portion is clear and no bleeding is observed Δ: The boundary portion is slightly blurred but no bleeding is observed ×: The boundary portion is unclear and bleeding is observed.
The results of evaluation are as shown in Table 1.

<Ink fixability>
When a black solid image was printed and scratched with a nail, the appearance was visually evaluated.
Evaluation printer: PM4000PX (Seiko Epson, pigment ink printer)
○: Fading does not occur in the printed part.
×: Fading occurs in the printed part.
The results of evaluation are as shown in Table 1.

From Table 1, it can be seen that the ink jet recording media produced in Examples 1 and 2 have good ink absorption, and the coloring of the dye ink and the pigment ink is high.
On the other hand, in the comparative example 1 which does not mix colloidal silica, the color density is inferior. In Comparative Example 2 in which no synthetic amorphous silica was blended, the ink absorptivity and ink fixability were inferior.

Claims (3)

In an inkjet recording medium having one or more coating layers on a support, wherein the outermost coating layer of the coating layers is an ink receiving layer mainly composed of a pigment and a hydrophilic binder, The pigment contained in the ink receiving layer is mainly synthetic amorphous silica and colloidal silica, and the mass blending ratio thereof is synthetic amorphous silica: colloidal silica = 98: 2 to 60:40, and the ink receiving layer surface. An ink-jet recording medium having a 75-degree specular gloss measured by 1 to 15% or less. 2. The ink jet recording medium according to claim 1, wherein the colloidal silica has a primary particle diameter of 5 to 40 nm and a chain shape or an association shape. 3. The ink jet recording medium according to claim 1, wherein the synthetic amorphous silica has a secondary average particle diameter of 5 to 20 μm and an oil absorption of 180 to 400 ml / 100 g.