JP3261992B2 - Ink jet recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording system for recording on a recording medium by using an aqueous ink, which has excellent ink absorbency and image reproducibility, and has sufficient surface strength as office paper. Provided is a recording medium for ink jet which also has a writing property with a pencil or the like.

[0002]

2. Description of the Related Art An ink jet recording system using an aqueous ink has a low noise at the time of recording, is easy to colorize, and is capable of high-speed recording. Applications to form printing and the like are being promoted. Because high-quality paper and coated paper used for general printing have poor ink absorption,
The printed ink does not dry on the paper surface and remains for a long time,
Practicality is poor because the apparatus and the continuously printed sheet are contaminated or the image becomes dirty. In order to solve such a problem, a recording paper having a small size is used (Japanese Patent Laid-Open No.
No. 53012) or a base paper containing a urea-formalin resin impregnated with a water-soluble polymer.
No. 49113). Further, recording papers coated with various porous inorganic pigments such as amorphous silica on the surface for the purpose of enhancing the color development and reproducibility of the ink (JP-A-55-51583, JP-A-5-51583)
No. 6-148585) is disclosed. Further, the physical properties of these porous pigments are specified for the purpose of obtaining a high-definition image with reduced bleeding (Japanese Patent Application Laid-Open No. 58-110287,
JP-A-59-185690, JP-A-61-141
No. 584) has been proposed. However, although the recording medium in the above-mentioned proposal can obtain image clarity, reproducibility, and ink absorbency, it is not always compatible with sufficient surface strength, and it is inferior in writing with a pencil. Lacked aptitude and was unsatisfactory.

[0003] In order to improve the suitability as office paper, such as the writing performance with a pencil, for example, JP-A-57-10787.
As disclosed in Japanese Patent Application Publication No. 8 (1994) -208, the use of a writability improver has been proposed, but these writability improvers do not contribute to the absorption of the water-soluble ink used for printing. When mixed and used in a layer, there is a problem that the shape of the print dot becomes irregular, resulting in a problem such as a decrease in image reproducibility. In addition, Japanese Unexamined Patent Publication No.
Japanese Patent No. 16379 proposes to appropriately use two or more types of porous pigments having different pore radii for the purpose of achieving both image reproducibility and pencil writing performance. However, if the coating amount is increased to obtain a higher definition image, the surface strength is reduced, and this is not always satisfactory.

[0004]

SUMMARY OF THE INVENTION The above disadvantages have been improved,
Not only can you record high-definition images with good reproducibility,
In order to obtain an ink jet recording medium having sufficient surface strength as office paper and having writability with a pencil, the present inventors have intensively studied the materials used for the recording medium, particularly the materials for forming the ink receiving layer. As a result, they found that an ink jet recording medium excellent in not only the reproducibility of an image but also the suitability as office paper was obtained, and completed the present invention. The present invention provides an ink jet recording medium which is excellent not only in image reproducibility but also in suitability as office paper.

[0005]

The present invention includes the following aspects. [1] An amorphous silicon having an aggregate secondary particle structure on a support
An ink jet recording medium comprising an ink receiving layer containing silica pigment, the ink receiving layer, BET type specific surface area of 360m 2 ^/ g~500m 2 ^{/ g} of aggregate secondary particles
Amorphous silica containing particles with a secondary particle diameter of 10μ or more
Containing a pigment, an amorphous silica pigment aggregate secondary particles of 100m ² / g~330m ² / g, the BET specific surface area
Non but the aggregate secondary particles of 360m ² / g~500m ² / g
The particle diameter of the primary particles forming the crystalline silica pigment is from 20 to
In the range of 70 Å, the BET specific surface area of 360m ² / g~500m ² / g secondary particle amorphous
An ink jet recording medium characterized in that a pigment of 10 μm or more in the secondary particle size distribution of the silica pigment occupies 8% by weight to 30% by weight of the ink receiving layer.

[0006]

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The BET specific surface area is 360 m ² /
g to 500 m ² / g of aggregated secondary particles of amorphous silica;
Coagulation BET specific surface area of 100m ² / g~330m ² / g
Amorphous silica of the aggregate secondary particles is used in combination.

As described above, various pigments having a large particle size, which have been proposed as means for improving pencil writing properties, are selected without necessarily considering their contribution to ink receptivity. Those satisfying the reproducibility were not obtained. The specific surface area used in the present invention is 360 m ^2.
agglomerated secondary particles containing a specific amount of particles having a secondary particle diameter of 10 μm / g to 500 m ² / g , amorphous silica itself has a certain degree of ink absorption, It is intended to provide an ink-jet recording medium which contributes, and at the same time, has a strong bond between primary particles forming the same and has a moderately uneven surface, and is excellent in suitability as office paper such as pencil writing. . The particle size and content of the aggregate particles are determined by, for example, measuring the particle size distribution of the aggregate dispersed in water by an appropriate method using a Coulter counter method, or directly observing the surface of the receiving layer with a microscope. Can be.

Assuming that the bonds involved in connecting the primary particles to each other to form secondary particles are uniformly distributed on the surface of the primary particles, the total number of the bonds is proportional to the surface area of the particles. It is presumed that the larger the number, the larger the number of bonds per weight and the more likely it is to form a strong aggregate as a whole.

[0010] Those having a primary particle size of less than 70 angstroms are excellent in the strength of the aggregate. However, the aggregate secondary particles having a primary particle diameter smaller than 20 angstroms have small gaps between the primary particles, and the effect that the solvent molecules of the ink enter these gaps and are absorbed cannot be expected. In order to be able to quickly absorb the ink and obtain sufficient ink jet printability, it is preferable to use one having a primary particle size of greater than 20 angstroms. That is, among the aggregate pigments used in the present invention, those having a primary particle size in the range of 20 to 70 angstroms are strong as particles and contribute to pencil writing,
Since it has a certain degree of ink absorbency, it can be estimated that it is useful for achieving both ink jet printability and pencil writing characteristics, which are the objects of the present invention. The primary particle diameter can be directly measured by observing the surface of the paper or the surface of the aggregated particles using, for example, an electron microscope.

The aggregate secondary particle pigments are formed by agglomerating smaller primary particles with each other, and the ink is quickly dried and adjoined by being absorbed and absorbed in the gaps between these primary particles. It is presumed that dots to be printed can be printed without blurring. The present invention uses an ink jet recording medium having excellent suitability as office paper without impairing ink jet recording suitability such as ink absorbability by using two or more kinds of aggregate secondary particle pigments having a specific specific surface area in combination. Is what you get. Since specific surface area agglomerates secondary particles of 100m 2 ^/ g~330m 2 ^/ g is to be rapidly absorbed the ink, although contributing to the formation of good ink-receiving layer to a high-definition image reproduction, binding of the aggregates Is weak, and there is a problem in workability such as pencil writing property. Therefore, it is not possible to achieve both the suitability for inkjet printing and the suitability as office paper, which are the objects of the present invention, but the specific surface area described above is 360 m ² / The combined use of g- 500 m ² / g aggregate secondary particles at a specific ratio eliminates the above-mentioned drawbacks and satisfies pencil writing without impairing reproducibility of high-definition images.

Specifically, the specific surface area is from 360 m ² / g to
In the particle size distribution of the aggregate of 500 m ² / g , the particles corresponding to the particle fraction of 10 μ or more are contained in 8 to 30% by weight of the whole receiving layer, whereby the pencil writing property intended in the present invention is obtained. Can be By the way, if it is less than 8%, sufficient pencil writability cannot be obtained, and if it is more than 30%, adverse effects such as irregularities in the shape of print dots and a decrease in print density occur, which is not preferable. If it is less than 8%, the unevenness of the surface of the coating layer is small, it is not possible to effectively scrape the core of the pencil to leave a clear handwriting, and the core is slippery and the writing quality is poor, which is not preferable. On the other hand, if it exceeds 30%, secondary particles having a large particle diameter, which are difficult to be dyed on the surface of the ink receiving layer, are exposed, so that the dot shape of ink jet printing tends to be irregular.

Further, in order to realize the suitability for ink jet printing which is the object of the present invention, it is necessary to use B as an ink receiving layer.
The ET specific surface area is desirably 350 m ² / g or less. The specific surface area of the ink receiving layer is, for example, about the ink receiving layer peeled from the substrate using a sharp knife or the like,
It can be measured by an ordinary method.

[0014]

Further, in the present invention, amorphous silica is used as the above-mentioned aggregate secondary particle pigment . Amorphous silica is synthesized from silicon tetrachloride by a gas phase method or from sodium silicate by a wet method such as a gel method or a sedimentation method. Is commercially available, so that the material having the physical properties specified in the present invention can be appropriately selected.

The base material of the recording medium is not necessarily limited, but a filler such as talc, kaolin, calcined kaolin, calcium carbonate or the like is added to the pulp for paper making, if necessary. Base paper, synthetic paper, film, and the like prepared by the method being used can be used as appropriate. In addition, a dry or wet nonwoven fabric or the like can be used as the substrate.

The means for coating the ink receiving layer can be appropriately selected from commonly used coating means such as a size press, a gate roll, a roll coater, a bar coater, an air knife coater, a rod blade coater and a blade coater. . The coating amount is not particularly limited,
1g / m ² ~50g / m ^2, preferably about 2~30g
/ M ² . Further, when performing color recording or for obtaining high-definition recording, the coating amount is 5 g / m ^{2 to} 30 g.
/ M ² is preferred.

In order to coat the ink receiving layer, in addition to the specific inorganic pigment of the present invention, if necessary, for example, calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc carbonate, Inorganic pigments such as satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, amorphous silica, alumina, aluminum hydroxide, etc., and organic pigments based on styrene, acrylic, urea resin, melamine resin, and benzoguanamine resin Can also be used in combination. Further, as a binder, starch and its derivatives, carboxymethylcellulose, hydroxyethylcellulose, casein, gelatin, natural or semi-synthetic polymers such as soybean protein, polyvinyl alcohol and its derivatives, polyvinyl butyral resin, polyethyleneimine resin, polyvinylpyrrolidone Resin, poly (meth) acrylic resin, acrylate resin, polyamide resin, polyacrylamide resin, polyester resin, urea resin, melamine resin, styrene / butadiene copolymer, methyl methacrylate / butadiene copolymer Aqueous solution or aqueous dispersion of vinyl copolymer resin such as ethylene-vinyl acetate copolymer,
Alternatively, a known material such as a modified polymer in which an anionic or cationic residue is introduced into the above resins can be used as appropriate.

In order to improve the water resistance of images printed with aqueous inks, polyethyleneimine resins, polyamine resins, polyamide resins, polyamide epichlorohydrin resins, polyamine epichlorohydrin resins, polyamide polyamine epichlorohydrin resins, polydiallylamine resins A cationic polymer compound such as a resin and a dicyandiamide condensate can be used in combination. Further, if necessary, a pigment dispersant, a thickener, an antifoaming agent, a foam inhibitor, a foaming agent,
Release agents, penetrants, wetting agents, thermal gelling agents, lubricants, and other auxiliaries known in the art can also be used.

The aqueous ink used in the present invention contains at least one of a water-soluble direct dye and a water-soluble acid dye as a dye. Contains fungicides and the like. Examples of the water-soluble direct dye include CI. Direct Black, CI. Direct Yellow, CI. Direct Blue, CI. Direct red and the like, and examples of the water-soluble acid dye include CI.
Acid Black, CI. Acid Yellow, CI. Acid Blue, CI. Acid Red and the like can be mentioned, but it is not necessarily limited to these.

[0021]

The present invention will be described in more detail with reference to the following examples, but it should be understood that the present invention is by no means restricted to these examples. In the examples, parts and% mean parts by weight and% by weight. The methods for measuring various physical property values in the examples are shown below. 1) Image reproducibility Seiko Epson inkjet printer MJ7
Printing of density gradation was performed at a recording density of 720 dpi using 00V2C, and the linearity of the printing area ratio and the printing density was used as a measure of image reproducibility. ：: Excellent in linearity between print area ratio and print density. Δ: Poor linearity between print area ratio and print density. 2) Print drying property Solid printing was performed using an ink jet printer (DeskJet 560J, manufactured by Hewlett-Packard Company), the dry state of the portion was visually evaluated, and the time until drying was used as a measure of print dryness. ：: excellent drying property. Δ: Slightly poor drying property. X: Poor drying property. 3) Pencil Writability In handwriting with a pencil (H), evaluation was made based on the presence or absence of the ink receiving layer and the degree of clarity of the handwriting. ：: The ink receiving layer did not fall off and the handwriting was clear. Δ: Dropout of the ink receiving layer was observed. Handwriting is also poor. X: The ink receiving layer was detached, and the handwriting was unclear.

Example 1 Amorphous silica pigment containing 20% of particles having a particle diameter of 10 μ or more (trade name: Carplex # 67; median particle diameter (central cumulative value, hereinafter simply referred to as average particle diameter): about 5 μ, 50 parts of primary particle diameter of about 55 Å, specific surface area of 430 m ² / g, manufactured by Shionogi & Co., Ltd. and 50 parts of amorphous silica pigment (trade name: Fine Seal X-37; average particle diameter of about 3 μm, primary particle diameter of about 30 μm) 100 angstroms, specific surface area 240-28
35 parts (0 m ² / g, manufactured by Tokuyama Corporation) were dispersed in 500 parts of a 1% aqueous solution of a polyamide resin (trade name: Polyfix 3000, manufactured by Showa Polymer Co., Ltd.) and used as a binder. 10% aqueous solution of polyvinyl alcohol (trade name: Kuraray Poval PVA-117, manufactured by Kuraray Co., Ltd.)
50 parts were added to obtain a coating liquid for an ink receiving layer containing about 10% of the total solid content of secondary particles having a specific surface area of 430 m ² / g and having a particle diameter of 10 μm or more of Carplex # 67. Basis weight 70g /
The coated paper was dried using a Myr bar so that the coated amount after drying on high-quality paper having a m ^{2 of} 5 seconds and a coating weight of 5 seconds was 10 g / m ^2, and then supercalendering was performed to obtain an ink jet recording medium. .

Example 2 Amorphous silica pigment containing 50% of particles having a particle diameter of 10 μ or more (trade name: Carplex BS-304N; average particle diameter: about 10 μ, primary particle diameter: about 55 Å, specific surface area: 400 m ² / g, manufactured by Shionogi & Co., Ltd.) and 45 parts of an amorphous silica pigment (trade name: Fine Seal X-37; average particle diameter: about 3 μm, primary particle diameter: about 100 Å),
Specific surface area 240-280m ² / g, manufactured by Tokuyama Corporation 4
0 parts of polyamide resin (trade name: Polyfix 30)
An ink-jet recording medium was obtained in the same manner as in Example 1 except that a dispersion liquid dispersed in 500 parts of a 1% aqueous solution of a 1% aqueous solution of S.I.

Example 3 Amorphous silica pigment containing 30% of particles having a particle diameter of 10 μ or more (trade name: Mizukasorb C-1; average particle diameter of about 7 μ,
Primary particle size about 50 Å, specific surface area 410 m
² / g, Mizusawa Chemical Co., Ltd.) 60 parts and amorphous silica pigment (trade name: Fine Seal X-37; average particle size: about 3)
μ, primary particle diameter about 100 Å, specific surface area 2
40 to 280 m ² / g, manufactured by Tokuyama Corporation)
An ink jet recording medium was obtained in the same manner as in Example 1 except that a dispersion liquid of a polyamide resin (trade name: Polyfix 3000, manufactured by Showa Kogaku KK) in 500 parts of a 1% aqueous solution was used.

Comparative Example 1 Amorphous silica pigment (trade name: Fine Seal X-37;
80 parts of an average particle diameter of about 3 μ, a primary particle diameter of about 100 Å, a specific surface area of 240 to 280 m ² / g, manufactured by Tokuyama Corporation, and a polyamide resin (trade name: Polyfix 3000, manufactured by Showa Polymer Co., Ltd.) 1% aqueous solution of 500
An ink jet recording medium was obtained in the same manner as in Example 1 except that the dispersion liquid dispersed in the parts was used.

Comparative Example 2 Amorphous silica pigment containing 50% of particles having a particle diameter of 10 μ or more (trade name: Mizukasil P-78F; average particle diameter: about 12)
μ, primary particle size about 60 Å, specific surface area 39
0 m ² / g, manufactured by Mizusawa Chemical Co., Ltd. (80 parts) was dispersed in 500 parts of a 1% aqueous solution of a polyamide resin (trade name: Polyfix 3000, manufactured by Showa Polymer Co., Ltd.). In the same manner as in Example 1, an inkjet recording medium was obtained.

Comparative Example 3 Amorphous silica pigment containing less than 3% of particles having a particle diameter of 10 μm or more (trade name: Carplex BS-304)
F; average particle size of about 4 μm, primary particle size of about 55 Å, specific surface area of 440 m ² / g, manufactured by Shionogi & Co., Ltd.) 80
Part with polyamide resin (trade name: Polyfix 300)
0, manufactured by Showa Polymer Co., Ltd.) to obtain an ink jet recording medium in the same manner as in Example 1 except that a dispersion liquid dispersed in 500 parts of a 1% aqueous solution was used.

Comparative Example 4 Amorphous silica pigment containing 50% of particles having a particle diameter of 10 μ or more (trade name: Carplex BS-304N; average particle diameter: about 10 μ, primary particle diameter: about 60 Å, specific surface area: 400 m ² / g, manufactured by Shionogi & Co., Ltd.) except that 80 parts of a 1% aqueous solution of a polyamide resin (trade name: Polyfix 3000, manufactured by Showa Polymer Co., Ltd.) was dispersed in 500 parts. In the same manner as in Example 1, an ink jet recording medium was obtained.

Comparative Example 5 Amorphous silica pigment containing 50% of particles having a particle diameter of not less than 10 μm (trade name: Toksir GU-N; average particle diameter of about 10)
μ, primary particle size about 150 Å, specific surface area 1
50 to 220 m ² / g, manufactured by Tokuyama Corporation) 40 parts and an amorphous silica pigment (trade name: Fine Seal X-37; average particle size: about 3 μm, primary particle size: about 100 Å,
Specific surface area 240-280m ² / g, manufactured by Tokuyama Corporation 4
0 parts of polyamide resin (trade name: Polyfix 30)
An ink jet recording medium was obtained in the same manner as in Example 1, except that a dispersion liquid dispersed in 500 parts of a 1% aqueous solution of a 1% aqueous solution of S.I.

Comparative Example 6 Amorphous silica pigment containing 80% of particles having a particle diameter of 10 μ or more (trade name: Sylysia # 470; average particle diameter: about 20)
μ, primary particle size about 80 Å, specific surface area 30
0 m ² / g, manufactured by Fuji Silysia Chemical Ltd.) and 25 parts of amorphous silica pigment (trade name: Fine Seal X-37; average particle diameter: about 3 μm, primary particle diameter: about 100 Å, specific surface area: 240 to 280 m ²⁾ / g, manufactured by Tokuyama Corporation) 55
Part with polyamide resin (trade name: Polyfix 300)
0, manufactured by Showa Polymer Co., Ltd.) to obtain an ink jet recording medium in the same manner as in Example 1 except that a dispersion liquid dispersed in 500 parts of a 1% aqueous solution was used.

Comparative Example 7 Amorphous silica pigment containing 50% of particles having a particle diameter of 10 μ or more (trade name: Carplex BS-304N; average particle diameter: about 10 μ, primary particle diameter: about 60 Å, specific surface area: 400 m ² / g, manufactured by Shionogi & Co., Ltd.) and amorphous silica pigment (trade name: Carplex BS-304)
F; average particle diameter of about 4 μm, primary particle diameter of about 55 Å, specific surface area of 440 m ² / g, manufactured by Shionogi & Co., Ltd.) 65
Part with polyamide resin (trade name: Polyfix 300)
0, manufactured by Showa Polymer Co., Ltd.) to obtain an ink jet recording medium in the same manner as in Example 1 except that a dispersion liquid dispersed in 500 parts of a 1% aqueous solution was used.

Table 1 shows the results of evaluating the image reproducibility, print density, print dryness and pencil writability of the above ten types of recording media.

[0033]

[Table 1]

[0034]

As is clear from Table 1, the examples of the present invention are ink jet recording media which are excellent in all of the image reproducibility, print density, print dryness and pencil writing properties as compared with the comparative examples. In order to improve the ink absorption, the coating amount of the ink receiving layer may be increased, for example, more than 5 g / m ^2. However, as the coating amount increases, the strength of the coating layer tends to decrease. In the present invention, an ink jet recording medium that satisfies all the above-mentioned needs can be provided by selectively using pigments having characteristics.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-16379 (JP, A) JP-A-62-244689 (JP, A) JP-A-1-108083 (JP, A) JP-A-3- 203966 (JP, A) JP-A-3-281283 (JP, A) JP-A-8-11424 (JP, A) JP-A-8-72387 (JP, A) JP-A-8-174993 (JP, A) JP-A-58-110287 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/00

Claims (2)

(57) [Claims] Claims: 1. A non- aqueous material having an aggregate secondary particle structure on a support.
An ink jet recording medium provided with an ink receiving layer containing a crystalline silica pigment , wherein the ink receiving layer is a BE.
Aggregates of T-type specific surface area of 360m ² / g~500m ² / g
Amorphous secondary particles containing particles with a secondary particle diameter of 10μ or more
Containing a silica pigment, the amorphous silica pigment aggregate secondary particles of 100m ² / g~330m ² / g, the BET specific
Surface area of 360m ² / g~500m ² / g of aggregate secondary particles
The primary particles forming the amorphous silica pigment have a particle size of 2
0 to 70 angstroms, and the BET
Secondary particles of formula specific surface area of 360m ² / g~500m ² / g
An ink jet recording medium, wherein the pigment of 10 μm or more in the secondary particle size distribution of the amorphous silica pigment occupies 8% by weight to 30% by weight of the ink receiving layer. 2. The coating amount of the ink receiving layer is 5 g / m. ² ~ 30
g / m ² 2. The ink jet recording medium according to claim 1, wherein
body.