JP2007130906A - Silica for inkjet recording paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide silica for inkjet recording paper which shows an excellent printing performance, without impairing a dye-pigment performance for both of a pigment ink and a dye ink. <P>SOLUTION: Surface-coated silica for the inkjet recording paper is constituted by a method wherein a silica particle having a BET specific surface area of 250-550 m<SP>2</SP>/g, an oil absorption of 200 ml/100 g or more and an average particle diameter of 10 μm or less is made to carry on the surface an acetylene glycol based nonionic surfactant of 0.1-20 mass% to the mass of the silica particle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to silica for inkjet recording paper. Specifically, the present invention is an ink jet that has high color developability when printed with a pigment ink type ink jet printer without damaging the performance of a dye ink type ink jet printer, can be printed clearly, and has less bleeding. The present invention relates to silica for recording paper.

  Inkjet printing with low noise and high-speed, high-performance color printing has grown rapidly in recent years, but in order to achieve high-performance printing, amorphous silica is coated on the surface. Recorded recording sheets (inkjet paper) are also widely used.

  The characteristics required for a recording sheet used for printing by an ink jet recording method are that ink droplets adhering to the coating layer on the surface of the ink jet recording sheet are quickly absorbed inside, and the ink is as close to the surface as possible. It is necessary to stay, and the roundness of the dots is maintained, the bleeding is small, and the color is good.

  Various inorganic materials such as silica, alumina, calcium carbonate, barium sulfate, zinc oxide, titanium oxide, etc. are used to impart these properties to the coating layer on the surface of base paper (film, synthetic paper, cloth, etc. in addition to paper). If necessary, fine particles are coated on the base paper together with a binder.

  Silica is the most representative of these inorganic fine particles, and amorphous silica having various physical properties is often used.

  Silica is generally classified into dry process silica obtained by burning silane-based gas such as silicon tetrachloride in oxyhydrogen flame, and wet process silica obtained by neutralization reaction of alkali metal silicate aqueous solution and mineral acid. Further, silicas belonging to wet process silica can be classified into precipitated silica and gel process silica according to the production method. These are used in accordance with the purpose of use by variously controlling the porous structure, specific surface area, surface state, etc. of silica according to the production conditions.

  As silica suitable for inkjet recording paper, for example, in Japanese Patent Publication No. 5-71394 (Patent Document 1), the average particle diameter is 2.5 to 3.5 μm, and the pore measurement by nitrogen adsorption is 60 to 130 mm. It has been proposed to use silica having pores in the range of 20% or more of all pores and an oil absorption of 250 ml / 100 g or more.

In JP-A-9-95042 (Patent Document 2), the BET specific surface area is 270 to 400 m ² / g, the peak position of the pore radius measured by the mercury intrusion method is 37.5 to 75 mm, the average particle diameter Has been proposed in the range of 3.5 to 10 μm.

  Inkjet printer inks are roughly classified into dye inks and pigment inks. Conventionally, dye ink has been mainstream in personal use, but pigment ink is becoming mainstream recently.

  Conventional dye inks are widely used because they have a wide color reproduction range and high saturation, but they are water-soluble and have relatively low water resistance, and the dye is decomposed by light and gas. Therefore, it has been a problem that the image storage stability (light resistance, gas resistance, ozone resistance) is low.

  On the other hand, the pigment ink, even if the pigment on the surface of the particle is destroyed by light and gas, the pigment existing below it develops color, apparently does not fade, and exhibits excellent image preservation, but is involved in color development. Since this is only a part of the pigment on the particle surface, the color developability is low and the image becomes dull compared to the pigment present in the ink.

  In recent years, in order to improve the color developability of pigment inks, the pigments have been improved by improving the color developability of the ink itself by making the pigment particles finer or microencapsulated. Has been increasing. Along with this, the number of ink jet recording papers for both dye and pigment inks is also increasing. Even when printing with pigment ink on the paper, it is required to have the same color as the dye ink, but it still cannot be said to have sufficient color development, and there is a need for further improvement in color development. It is.

When designing dye / pigment / paper as described above, excellent color developability is required even when printing with pigment ink without impairing the performance of the dye ink. In the case of dye ink, a certain degree of printing performance can be obtained if it is an amorphous silica having a BET specific surface area of 250 to 550 m ² / g, an oil absorption of 200 ml / 100 g or more, and an average particle diameter of 10 μm or less by the Coulter counter method. However, even the optimum physical properties for dye inks are not necessarily optimal for pigment inks. Unlike the dye ink, the pigment ink is different from the dye ink in that only one part of the particle on the surface is caused by the color development. Therefore, it is necessary to make the pigment particle float on the surface as much as possible. Although relatively large particles may be used to make the surface stand out, if the particle size of the dye ink is too large, ink bleeding occurs and a clear image cannot be obtained. Accordingly, silica that is optimal for pigment ink is not optimal for dye ink, and it has been necessary to sacrifice any performance when trying to develop a so-called dye / pigment paper.

  In order to solve these problems, for example, in Japanese Patent Application Laid-Open No. 2001-270238 (Patent Document 3), the average particle diameter is 2 to 17 μm on the support, and amorphous silica, alumina, and alumina hydrate are used. , An ink jet recording medium comprising an ink receiving layer containing at least one pigment selected from aluminosilicate and hydrotalcite group minerals and an adhesive, wherein the adhesive is a vinyl chloride-vinyl acetate copolymer An ink jet recording medium characterized by containing the above has been proposed.

  In JP-A-2003-285541 (Patent Document 4), in an inkjet recording sheet in which an ink receiving layer is provided on the surface of a support, a glossy expression layer mainly composed of inorganic fine particles is provided on the uppermost layer of the recording sheet. In addition, a synthetic amorphous silica-containing ink receiving layer comprising at least two layers is formed under the gloss expressing layer, and the average particle diameter of the synthetic amorphous silica is sequentially reduced from the lower layer to the upper layer of each ink receiving layer. It has been proposed to do so. However, none of these methods is sufficient to solve the problem.

In JP-A-2005-153221 (Patent Document 5), in an inkjet recording sheet in which a coating layer containing a pigment, an adhesive and an ink fixing agent is provided on a support, the coating layer contains a surfactant. An ink jet recording sheet containing 0.5% of contact angle with distilled water on the surface of the coating layer and having a contact angle of 10 to 30 °, a pigment, an adhesive, and an ink fixing agent on the support An ink jet recording sheet provided with a coating layer containing an ink jet recording sheet characterized in that a pigment whose surface is treated with a surfactant is used as at least a part of the pigment.
Japanese Patent Publication No. 5-71394 JP-A-9-95042 JP 2001-270238 A JP 2003-285541 A JP 2005-153221 A

  However, none of the methods described in Patent Documents 3 and 4 are sufficient to solve the above problems. In addition, the ink jet recording sheet described in Patent Document 5 can achieve a certain effect, but cannot be said to have sufficient performance, and needs to be further improved.

  Accordingly, an object of the present invention is to provide silica for ink jet recording paper, which exhibits excellent printing performance for both pigment ink and dye ink.

  As a result of diligent investigations to improve the printing performance with pigment ink without impairing the performance of the dye ink in the dye / pigment ink combined paper, the present inventors have obtained a surfactant having a specific structure. When silica coated on the surface is used, it has been found that the color developability of pigment printing is improved without impairing dye performance, and the present invention has been completed.

The present invention for solving the above problems is as follows.
[1] Silica for inkjet recording paper, characterized in that 0.1 to 20% by mass of an acetylene glycol-based nonionic surfactant is supported on the surface of the silica particles with respect to the mass of the silica particles.
[2] The silica according to [1], wherein the silica particles have a BET specific surface area of 250 to 550 m ² / g, an oil absorption of 200 ml / 100 g or more, and an average particle size of 10 μm or less by a Coulter counter method.
[3] The silica according to [1] or [2], wherein the acetylene glycol-based nonionic surfactant is acetylene glycol represented by the following general formula (1).

(式中、R¹及びR²はそれぞれ炭素数1〜5のアルキル基を示す。）
［４］アセチレングリコール系の非イオン性界面活性剤が、下記一般式(2)で表されるアセチレングリコールのエトキシル化体である[１]または[２]に記載のシリカ。

(In the formula, R ¹ and R ² each represent an alkyl group having 1 to 5 carbon atoms.)
[4] The silica according to [1] or [2], wherein the acetylene glycol-based nonionic surfactant is an ethoxylated acetylene glycol represented by the following general formula (2).

（式中、R¹及びR²はそれぞれ炭素数１〜５のアルキル基を示し、ｍ及びｎはそれぞれ０．５〜２５であり、ｍ＋ｎは１〜４０である。）

(In the formula, R ¹ and R ² each represent an alkyl group having 1 to 5 carbon atoms, m and n are each 0.5 to 25, and m + n is 1 to 40.)

  According to the present invention, the color development of printing with a pigment ink type ink jet printer is improved without impairing the dye performance of the dye ink type ink jet printer, and the ink jet recording can be clearly printed with less bleeding. Silica for paper can be provided. Furthermore, this ink jet recording paper using silica has improved color development for pigment printing without impairing dye performance.

  The silica for ink jet recording paper of the present invention is characterized in that 0.1 to 20% by mass of an acetylene glycol-based nonionic surfactant is supported on the surface of the silica particles with respect to the mass of the silica particles. To do.

  In the present invention, the silica used for supporting the acetylene glycol-based nonionic surfactant is not particularly limited as long as it is amorphous silica. Examples of amorphous silica include precipitated silica and gel silica, but gel silica that has large pores to absorb ink droplets inside and is characterized by a hard structure. Is preferred.

  There is no restriction | limiting in particular in the manufacturing method of a gel method silica. For example, a silica hydrosol is formed by rapidly shearing and mixing a sodium silicate aqueous solution and a mineral acid using a nozzle, and the silica hydrogel is obtained by leaving the silica hydrosol for several hours. Thoroughly wash with neutralization to remove alkali ions, acid ions, salts, etc., then perform hydrothermal treatment to adjust BET specific surface area and pores, then dry and pulverize, if necessary A classification method can be given according to this. However, it is not the intention limited to this method.

Amorphous silica used in the present invention, for example, the range of BET specific surface area of 250~550m ² / g, preferably 280 to 480m ² / g range, oil absorption of 200 ml / 100 g or more, preferably 200 to 400 ml It is appropriate that the average particle diameter by the Coulter counter method is 10 μm or less, preferably 4 to 8 μm.

  Furthermore, the amorphous silica used in the present invention has a weight distribution ratio of particles of less than 2.52 μm in the total weight in the particle size distribution measurement by the Coulter counter method proposed in, for example, JP-A-2002-87811. It is more preferable to use amorphous silica having a sharp particle size distribution in which the weight distribution ratio of particles of 5.0% or less and 16.0 μm or more is 3.0% or less of the total weight. Outside this range, when printing with dye ink, problems such as a decrease in printing density, deterioration in ink absorbency, or occurrence of bleeding are caused.

  In the silica for inkjet recording paper of the present invention, the acetylene glycol-based nonionic surfactant supported on the surface of the silica particles can be acetylene glycol represented by the following general formula (1).

(式中、R¹及びR²はそれぞれ炭素数1〜5のアルキル基を示す。）
炭素数1〜5のアルキル基としては、例えば、メチル、エチル、ｉｓｏ−プロピル、ｎ−ブチル、ｔ−ブチルおよびｎ−ペンチルを挙げることができる。

(In the formula, R ¹ and R ² each represent an alkyl group having 1 to 5 carbon atoms.)
Examples of the alkyl group having 1 to 5 carbon atoms include methyl, ethyl, iso-propyl, n-butyl, t-butyl and n-pentyl.

  Examples of the acetylene glycol represented by the general formula (1) include 2,5,8,11-tetramethyl-6-dodecin-5,8-diol, 5,8-dimethyl-6-dodecin-5, 8-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 4,7 dimethyl-5-decyne-4,7-diol, 2,3,6,7-tetramethyl Mention may be made of -4-octyne-3,6 diol, 3,6 dimethyl-4-octyne-3,6-diol, or 2,5-hexyne-2,5 diol.

  In addition, the acetylene glycol-based nonionic surfactant may be an ethoxylated acetylene glycol represented by the following general formula (2).

（式中、R¹及びR²はそれぞれ炭素数１〜５のアルキル基を示し、ｍ及びｎはそれぞれ０．５〜２５であり、ｍ＋ｎは１〜４０である。）

(In the formula, R ¹ and R ² each represent an alkyl group having 1 to 5 carbon atoms, m and n are each 0.5 to 25, and m + n is 1 to 40.)

  Examples of the ethoxylated acetylene glycol represented by the general formula (2) include an ethylene oxide derivative of acetylene glycol. In addition to the ethylene oxide adduct, there is no problem even if it is an ethylene oxide / propylene oxide block type adduct or an ethylene oxide / propylene oxide random type adduct.

  The acetylene glycol-based surfactant can be used singly or in combination of two or more, and these surfactants have low dynamic surface tension, so they have excellent wettability, permeability, antifoaming properties, In order to exhibit dispersibility, it is applied to water-based materials in various directions.

  Further, in the present invention, it is essential to coat the silica surface with the above acetylene glycol-based nonionic surfactant, but other surfactants are used in combination with the acetylene glycol-based nonionic surfactant. A surfactant may be used. Examples of other surfactants include sodium n-hexylsulfosuccinate, sodium dihexylsulfosuccinate, sodium dioctylsulfosuccinate, sodium di (2-ethylhexyl) sulfosuccinate, potassium di (2-ethylhexyl) sulfosuccinate, sodium diamylsulfosuccinate, And sulfur-containing surfactants such as disodium 2-ethylhexylsulfosuccinate and dipotassium 2-ethylhexylsulfosuccinate. The combined use of sulfur-containing surfactants has the advantages of excellent wettability, permeability and dispersibility due to low surface tension, improved water solubility, and response to recent environmental problems. . Thus, the combined use of other surfactants for the purpose of imparting functions does not cause any problems in the present invention, and may be contained in an amount of 20 to 80% as necessary.

  As the acetylene glycol-based nonionic surfactant, for example, Surfinol series (for example, Surfinol A, Surfinol 104H, Surfinol 104E, Surfinol 420, Surfinol 440, Surfinol, manufactured by Air Products Japan Co., Ltd.) 465, Surfinol 504, Surfinol SE), Olphine series manufactured by Nissin Chemical Industry Co., Ltd. PD-002W) and the like.

  0.1 to 20% by mass of the acetylene glycol-based nonionic surfactant is supported on the surface of the silica particles with respect to the mass of the silica particles. The surface-active agent is supported on the surface of the silica particles by, for example, a method of pulverizing silica in the presence of a surfactant, a method of spray-drying slurryed silica together with a surfactant, or a mixer such as a Henschel mixer. This can be performed by a method of mixing silica and a surfactant. It is essential that the acetylene glycol-based nonionic surfactant covers the surface of the silica particles.

  0.1 to 20% by mass of the acetylene glycol-based nonionic surfactant is supported on the mass of the silica particles. If the amount of the surfactant is less than 0.1% by mass, the coating amount is too small and the desired effect of the present invention cannot be exhibited. On the other hand, when the amount of the surfactant exceeds 20% by mass, when the coating liquid is applied, the permeability to the base paper is abnormally improved, the coating becomes difficult, or the dispersion is prepared. The chewing of the foam becomes worse. Moreover, it is not preferable to use a large amount of an expensive surfactant in terms of production cost. If the amount of coating increases and permeability to the base paper becomes a problem, it can be solved by combining with silica that is not surface-coated, and optimal conditions can be taken in designing the coating layer .

  The supported amount of the acetylene glycol-based nonionic surfactant is preferably in the range of 0.5 to 10% by mass with respect to the mass of the silica particles.

  The silica of the present invention is suitably used as a filler for inkjet recording paper. Conventional methods can be used as they are for the mode of use and the production of ink jet recording paper using the silica of the present invention. The ink jet recording paper in which the silica of the present invention is used is preferably dye ink and pigment ink / paper.

  In order to explain the present invention more specifically, examples and comparative examples are shown below. In addition, each physical property value etc. were implemented by the following method.

Average particle diameter It measured using a 50 micrometer aperture tube using Coulter Multisizer II (Coulter Electronics Ltd. make: Coulter counter method). The sample was dispersed by ultrasonic dispersion for 40 seconds, and Isoton-II liquid was used as a dispersion medium.
The 50% value of the weight integrated value in the particle size distribution measured by the above method was defined as the average particle size.

Oil absorption measurement
The measurement was performed according to the oil absorption measurement method according to JIS K5101 (pigment test method).

BET specific surface area The BET specific surface area is 1 using a fully automatic powder specific surface area measuring apparatus AMS-8000 (manufactured by Okura Riken Co., Ltd.) according to JIS Z-8830 (method for measuring the specific surface area of powder by gas adsorption). It was measured by the point method.

Preparation of coating liquid and coated paper Add 160 ml of water and 40 g of silica to a 300 ml disposable cup and disperse with high speed mixer (40mmφ resolver blade) at 3000rpm (peripheral speed 6.3 / sec) for 20 minutes. Prepare a 20% slurry. 100 g of 10% aqueous solution of polyvinyl alcohol (PVA117 manufactured by Kuraray Co., Ltd.) and 13 g of water-soluble cationic polymer aqueous solution (Unisense CP-103 manufactured by Senka Co., Ltd.) are added to 150 g of 20% slurry and blended, and ink jet coating is performed. Liquid. This coating solution is applied to PPC paper with a basis weight of 66 g / m ² using a No. 30 bar coater, dried at 120 ° C. for 10 minutes, calendered at a linear pressure of 20 kg / cm, and coated paper Obtained.

Inkjet evaluation For the above-mentioned coated paper, printing such as single color solid coating and mixed color solid coating is performed using PM-800DC (dye ink type), PX-G900 (pigment ink type) manufactured by Epson Corporation, for evaluation of inkjet printing. A test piece was obtained. The test piece for printing evaluation was evaluated as follows.

(A) Printing Density Printing density measurement of each solid color of black, yellow, cyan, and magenta was performed using a Gretag Macbeth reflection densitometer RD-918. The higher the value, the higher the printing.

(B) Ink Absorbability Each black, yellow, cyan, and magenta single-color solid-coated portion was rubbed with a finger immediately after printing, the state was observed, and ink absorbency was evaluated according to the following evaluation criteria.
○… No ink adhesion on finger △… Slight ink adhesion on finger
×: Adherence of ink to the finger is observed.

(C) Bleeding Bleeding between the borders of each solid-colored portion of black, yellow, cyan, and magenta was observed with the naked eye using a video microscope (manufactured by SCARA Co., Ltd .: VSR-70A) and evaluated according to the following evaluation criteria. Evaluation was performed.
○… Ink does not flow or bleed even at the boundary between solid coatings.
Δ: When a color overlaps with a specific color, it may blur.
X: The boundary between solid coatings is totally blurred.

Example 1
A silica hydrosol was obtained by mixing a sodium silicate aqueous solution having a SiO2 concentration of 25 wt% and a SiO2 / Na2O molar ratio of 3.3 with a 40 wt% sulfuric acid aqueous solution so that the excess sulfuric acid was 0.6N. This silica hydrosol was allowed to stand for a while to obtain a silica hydrogel. After hydrothermal treatment at 90 ° C. and pH 9.5 for 12 hours, sulfuric acid was added until the excess sulfuric acid became 0.03 N in order to remove the alkali. The mixture was further left at 60 ° C. for 1 hour. Thereafter, sufficient water washing was performed to obtain a pure silica hydrogel. This silica hydrogel was dried with a dryer until the water content reached 50%, and then pulverized with a jet mill using heated steam, and further classified with an air classifier, with a BET specific surface area of 300 m ² / g, average A gel silica having a particle diameter of 4.5 μm and an oil absorption of 330 ml / 100 g was obtained.

  A predetermined amount of water is added to the gel method silica to form a slurry, and 8% by mass of acetylene glycol nonionic surfactant (Olfin PD-002W, manufactured by Nissin Chemical Industry Co., Ltd.) is added to the silica and stirred. The silica of the present invention was obtained by spray drying with an L-8 type spray dryer.

Example 2
The silica of the present invention was obtained in the same manner as in Example 1 except that the amount of the surfactant in Example 1 was 0.5% by mass with respect to the silica.

Comparative Example 1
Gel silica obtained by the same method as in Example 1 and not surface-coated with a surfactant.

Comparative Example 2
Gel silica prepared by surface coating with a polyoxyalkylene polyalkylene polyamine obtained by the same method as in Example 1.

Comparative Example 3
Gel silica obtained by surface coating with polyoxyethylene lauryl ether obtained by the same method as in Example 1.

  Table 1 shows the powder physical properties and ink jet evaluation results of the silica of Examples 1 and 2 and the silica of Comparative Examples 1 to 3.

Example 3
The same silica hydrogel as obtained in Example 1 was dried until the adhering moisture became 70%, this was pulverized by a jet mill using heated steam, further classified using an air classifier, and BET A gel silica having a specific surface area of 300 m ² / g, an average particle diameter of 6.5 μm, and an oil absorption of 260 ml / 100 g was obtained. To the obtained silica, 0.5% of acetylene glycol-based nonionic surfactant (Olfin PD-002W, manufactured by Nissin Chemical Industry Co., Ltd.) was added to silica, and dry-mixed with a Henschel mixer. .

Comparative Example 4
Gel silica obtained by the same method as in Example 4 and not surface-coated with a surfactant.

Comparative Example 5
Silica whose surface was not coated with the surfactant obtained in the same manner as in Example 4 was used, and 0.5% of an acetylene glycol-based nonionic surfactant was added to the silica when the coating liquid was prepared.

Comparative Example 6
Gel silica obtained by surface coating with a polyoxyalkylene polyalkylene polyamine obtained by the same method as in Example 4.

  Table 2 shows the powder physical properties and ink jet evaluation results of the silica of Example 3 and the silicas of Comparative Examples 4 to 6.

  The silica of Examples 1 to 3 has a high print density when printed with pigment ink without changing the print density when printed with dye ink. Conventionally, increasing only the pigment printing density can be improved to some extent by changing the silica physical properties, but the problem is that the dye printing performance is lowered. By using the silica of the present invention, the pigment printing density can be improved without degrading the dye printing performance. That is, the silica of the present invention exhibits a dye printing density equivalent to that of untreated silica suitable for dye inks, and is improved by about 0.1 in terms of an average of four pigment printing densities. In general, it can be said that the effect of increasing the pigment printing density by about 0.03 on the average of four colors is effective, and therefore the silica of the present invention exhibits an effect superior to that.

  The present invention is useful in the field of ink jet recording paper.

Claims (4)

A silica for inkjet recording paper, comprising 0.1 to 20% by mass of an acetylene glycol-based nonionic surfactant based on the mass of the silica particles on the surface of the silica particles. The silica according to claim 1, wherein the silica particles have a BET specific surface area of 250 to 550 m ² / g, an oil absorption of 200 ml / 100 g or more, and an average particle size of 10 μm or less by a Coulter counter method. 3. The silica according to claim 1, wherein the acetylene glycol-based nonionic surfactant is acetylene glycol represented by the following general formula (1).

(In the formula, R ¹ and R ² each represent an alkyl group having 1 to 5 carbon atoms.) 3. The silica according to claim 1, wherein the acetylene glycol-based nonionic surfactant is an ethoxylated product of acetylene glycol represented by the following general formula (2).

(In the formula, R ¹ and R ² each represent an alkyl group having 1 to 5 carbon atoms, m and n are each 0.5 to 25, and m + n is 1 to 40.)