JP2000239536A - Cationic resin-modified silica dispersion and method for producing the same - Google Patents

Abstract

(57) Abstract: Provided is a cationic resin-modified silica dispersion comprising silica fine particles having an average particle diameter of less than 200 nm and a cationic resin, in which aggregation of silica particles does not occur, and a method for producing the same. thing. A mixed solution obtained by mixing silica and a cationic resin in a polar solvent is treated at a processing pressure of 300 kgf / cm.
The average particle size of the silica particles in the dispersion obtained by making the particles collide with each other at ² or more or passing through the orifice under the condition that the differential pressure between the inlet side and the outlet side of the orifice is 300 kgf / cm ² or more is obtained. A cationic dispersion characterized by having a light scattering index (n) value of 2.0 or more measured for the dispersion diluted to a solid content concentration of less than 200 nm and 1.5% by weight. Resin-modified silica dispersion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cationic resin-modified silica dispersion and a method for producing the same. More specifically, the present invention provides a novel cationic resin-modified silica dispersion liquid useful as a raw material of a coating liquid for ink jet recording paper and a production method.

[0002]

2. Description of the Related Art Conventionally, a silica dispersion has been used as a raw material of a coating liquid for ink jet recording paper.
In order to improve the image density and the water resistance of the ink jet recording paper, a silica dispersion mixed with a cationizing reagent is used.

The silica dispersion used as a coating liquid for the above-mentioned ink jet recording paper is disclosed in
19037 discloses a cation-modified colloidal silica in which the silica surface is coated with a compound of a polyvalent metal ion such as aluminum ion, and Japanese Patent Publication No. 5-57114 discloses that the average aggregated particle diameter is 0.5 ~
There has been proposed a composition in which a cationic resin containing a quaternary ammonium group is mixed with 30 μm of synthetic silica.

[0004] However, the ink jet recording paper coated with the coating liquid using silica described in Japanese Patent Publication No. 19037/1992 has a drawback that its performance such as water resistance and color development is not sufficient. In addition, Japanese Patent Publication 5-57
Ink jet recording paper coated with a coating liquid using the composition described in JP-A No. 114 is improved in water resistance, color development, etc., but has large silica particles, so that the surface smoothness and glossiness are improved. Has the disadvantage of being low.

Therefore, in order to solve the above problems,
A cationized modified silica dispersion comprising silica fine particles having an average particle diameter of less than 200 nm and a cationic resin has been studied. In the present invention, the average particle diameter refers to a volume-based median diameter D ₅₀ as measured with a particle size distribution meter of the light scattering diffraction type.

[0006]

However, in general, when a cationic resin is mixed with a silica dispersion in which fine silica particles having an average particle diameter of less than 200 nm are dispersed, the silica particles are aggregated, resulting in a turbine stator type. Even if re-dispersed by a conventional dispersing machine such as a high-speed rotary stirring and dispersing machine (for example, a homogenizer), a colloid mill, an ultrasonic emulsifier, and the like, there is a problem that the original dispersion state is not restored.

When the average particle diameter of silica increases due to the aggregation of the silica particles, not only is the surface of the coating layer not smooth, but also the transmission of light is hindered. And a problem such as insufficient gloss occurs.

[0008] Accordingly, an object of the present invention is to prevent the above-mentioned agglomeration of silica particles from occurring and to achieve an average particle diameter of 20%.
It is an object of the present invention to provide a cationic resin-modified silica dispersion comprising silica fine particles having a particle diameter of less than 0 nm and a cationic resin, and a method for producing the same.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies on the above problems and found that the average particle size was 200
A mixture obtained by mixing silica fine particles having a diameter of less than 10 nm and a cationic resin in a polar solvent is treated at a processing pressure of 300 kgf.
/ Cm ² or more, or by passing through the orifice under the condition that the differential pressure between the inlet side and the outlet side of the orifice is 300 kgf / cm ² or more,
It was found that a silica dispersion liquid redispersed to the original dispersion state was formed.

That is, the present invention provides a dispersion in which silica and a cationic resin are dispersed in a polar solvent, wherein the average particle diameter of silica particles in the dispersion is less than 200 nm, and A cationic resin-modified silica dispersion having a light scattering index (n value) of 2.0 or more at a solid content of 1.5% by weight.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The silica used in the present invention is not particularly limited. Therefore, in the present invention,
Any known silica such as wet silica, dry silica, and sol-gel method silica can be used as a raw material.

The wet silica is typically precipitated silica formed by neutralizing sodium silicate with a mineral acid to precipitate silica in a solution, and is also referred to as white carbon. Similarly, a gel silica produced by neutralizing sodium silicate with an acid can also be used. Furthermore, a dehydrated silica cake which has only been subjected to filtration and washing after the neutralization reaction and which is not subjected to a drying step can be used.

The above-mentioned fumed silica is generally obtained by subjecting silicon tetrachloride to high-temperature hydrolysis in an oxygen-hydrogen flame, and is also called fumed silica.

The sol-gel method silica is generally obtained by hydrolyzing a silicon alkoxide such as tetramethoxysilane or tetraethoxysilane in an acidic or alkaline aqueous organic solvent.

In the present invention, among the above-mentioned silicas, wet silica and dry silica are preferred.

In the present invention, the cationic resin can be used without any particular limitation as long as it is a resin which dissociates and exhibits cationicity when dissolved in water.
A resin having a tertiary amine or a quaternary ammonium salt can be suitably used, and a resin having a quaternary ammonium salt is more preferable.

The polar solvent used in the present invention is not particularly limited as long as silica and the cationic resin are easily dispersed therein. As such a polar solvent,
Water; alcohols such as methanol, ethanol, and isopropyl alcohol; ethers; ketones; Among the polar solvents, water is preferred.
Further, a mixed solvent of water and the above polar solvent can also be used.

In order to improve the stability and dispersibility of the silica particles, a small amount of a surfactant or the like may be added to the cationic resin-modified silica dispersion of the present invention as long as the effects of the present invention are not impaired. Good.

In the present invention, the amounts of silica and the cationic resin in the cationic resin-modified silica dispersion are not particularly limited, but the amount of silica in the silica dispersion is 8% by weight to 50% by weight, and more preferably 8% by weight. % By weight is preferred, and the amount of the cationic resin is 3 to 100 parts by weight of silica.
~ 50 parts by weight are preferred.

The amount of silica in the silica dispersion is 50% by weight
If more, the fluidity of the slurry will be extremely poor,
Mixing with cationic resin becomes difficult, while 8% by weight
If the amount is smaller, a large apparatus is required for drying the dispersion, and the energy cost increases, which is not preferable.

When the amount of the cationic resin in the silica dispersion is
If the amount is less than 3 parts by weight per 100 parts by weight of silica, the balance of the surface charge of the silica particles becomes uneven, and the silica particles tend to undergo strong aggregation. On the other hand, when the amount of the cationic resin is more than 50 parts by weight per 100 parts by weight of silica, the viscosity becomes high and the dispersion treatment becomes difficult.

The silica particles in the cationic resin-modified silica dispersion of the present invention have a zeta potential as an index of surface charge of at least +10 mV, preferably at least +20 mV, more preferably at least +30 mV. The higher the zeta potential, the more effective the water resistance of the inkjet paper.
The zeta potential increases as the amount of the cationic resin mixed increases, but the range of increase depends on the type of the cationic resin mixed.

The cationic resin-modified silica dispersion of the present invention has an average particle diameter of 200 nm of silica particles in the dispersion.
It is necessary that the light scattering index (n value) measured for the dispersion diluted so as to have a solid content concentration of 1.5% by weight is not less than 2.0. The silica has an average particle diameter of more than 200 nm and an n value of 2.
When it is smaller than 0, when used as a raw material of a coating liquid for ink jet recording paper, not only the surface smoothness of the coating layer is not obtained, but also light transmission is hindered, and the coating layer becomes opaque, Problems such as insufficient gloss occur.

The above-mentioned light scattering index (n value) is an index of the dispersion state of silica in the dispersion, and this value increases as the dispersibility improves.

Note that the n value is the Journal of C
ceramic Society of Japan 1
01 [6] 707-712 (1993).

That is, the absorbance τ was determined by measuring the spectrum of a silica dispersion having a light wavelength (λ) in the range of 460 to 700 nm using a commercially available spectrophotometer.
og (λ) and log (τ) are plotted, and the slope (−n) of the straight line is obtained by the least square method using the following equation (1).

Τ = αλ ⁻ⁿ (1) (where τ is the absorbance, α is a constant, λ is the wavelength of light, and n is the light scattering index.) Theoretically, the possible values of n are 4 or less.

Specifically, the measurement conditions are as follows. First, a reference cell and a sample cell are filled with ion-exchanged water using a cell having an optical path length of 10 mm, and zero point calibration is performed over a wavelength range of 460 to 700 nm. Next, the dispersion is diluted with ion-exchanged water so that the solid content concentration of the dispersion is 1.5% by weight, and the diluted dispersion is placed in a sample cell, and a wavelength (λ) of 460 to 700 nm is obtained. Measure the absorbance (τ) of the range.

In the present invention, there is no particular limitation on the method for producing the cationic resin-modified silica dispersion. However, as a preferable production method, for example, a mixed solution obtained by mixing silica and a cationic resin in a polar solvent is opposed to each other at a processing pressure of 300 kgf / cm ² or more,
Or, the differential pressure between the inlet and outlet of the orifice is 300k
passing through an orifice under a condition of gf / cm ² or more.

The method for producing the above-mentioned mixed liquid of silica and cationic resin is not particularly limited, and a method of simply mixing silica and cationic resin in a polar solvent, a turbine stator type high-speed rotary stirring and dispersing machine (for example, A homogenizer, a colloid mill, a method of mixing a silica dispersion obtained by previously dispersing silica in a polar solvent using a conventional disperser, such as an ultrasonic emulsifier, and a cationic resin, A method in which a mixture of silica and a cationic resin is treated in a polar solvent using the above-mentioned conventional disperser.

The form of the silica used in the production method of the present invention is not particularly limited, and may be any form of powder, cake, slurry and dispersion.

Among them, a silica slurry or a silica dispersion in which powder, cake and the like are previously dispersed in a liquid medium is preferable, and a silica dispersion is particularly preferable.

Considering that the above-mentioned raw material of the silica slurry or silica dispersion can be efficiently dispersed and pulverized, a dehydrated silica cake of wet silica, which is not subjected to a drying step of merely performing filtration and washing after the neutralization reaction, is preferable. It is. Dry silica powder is preferred from the viewpoint of improving the dispersibility of the resulting cationic resin-modified silica dispersion.

Examples of the silica dispersion include a pulverized silica dispersion. Among them, a pulverized silica dispersion having an average particle diameter of less than 200 nm is preferable in consideration of the effects of the present invention. Specifically, a silica slurry in which various silicas are dispersed in a polar solvent is used in JP-A-9-1428.
Pulverized silica dispersions pulverized to a mean particle diameter of less than 200 nm according to the method described in JP-A-27-275 may be mentioned.

Particularly, the pulverized silica dispersion obtained by the method described in the above publication is composed of agglomerated particles in which several to several tens of primary particles are agglomerated. Can be suitably used in the field of

The term “pulverization” as used herein means not only that silica particles composed of strong agglomerated particles are crushed,
It also refers to crushing or dispersing to loosen the aggregation of silica particles composed of loosely aggregated particles.

In the present invention, the silica slurry refers to a slurry which is almost precipitated when silica is dispersed in a liquid medium and then allowed to stand, and a silica dispersion refers to a silica dispersion after the silica is dispersed in the liquid medium. Refers to a substance that hardly precipitates when left standing.

When the above-mentioned silica slurry or silica dispersion is used, the silica concentration in the silica slurry or silica dispersion before mixing with the cationic resin is 50% by weight or less, preferably 30% by weight or less. And more preferably 20% by weight or less. 50% by weight
If the ratio exceeds, the fluidity becomes extremely poor, and it becomes difficult to mix the cationic resin.

In the present invention, a mixed solution obtained by mixing silica and a cationic resin in a polar solvent is opposed to each other at a processing pressure of 300 kgf / cm ² or more, or the difference between the inlet side and the outlet side of the orifice is determined. Pressure is 300kgf / c
As a device for passing the orifice under a condition of m ² or more, a commercially available device generally called a high-pressure homogenizer can be suitably used. Specific examples of representative examples of the high-pressure homogenizer include trade names of Nanomizer; trade names of Nanomizer and Microfluidics; microfluidizers; and Artimizer of Sugino Machine.

The orifice referred to here is a mechanism for inserting a thin plate (orifice plate) having a fine hole such as a circle into a straight pipe and rapidly narrowing the flow path of the straight pipe.

The high-pressure homogenizer is basically composed of
This is an apparatus comprising a high-pressure generating section for pressurizing the raw material slurry and an opposing collision section or an orifice section. As the high-pressure generating section, a high-pressure pump generally called a plunger pump is suitably used. There are various types of high pressure pumps, such as a series type, a double type, a triple type, and any type can be employed in the present invention without any particular limitation.

In the present invention, the processing pressure when a mixed solution obtained by mixing silica and a cationic resin in a polar solvent is opposed to each other, and the pressure difference between the inlet and outlet of the orifice when passing through an orifice. Are all 300 kgf / cm ² or more, preferably 8
00 kgf / cm ² or more, more preferably 1200 kf
gf / cm ² or more is desirable.

The collision speed of the mixed liquid in the case of the opposing collision is 50 m / sec or more as a relative speed, preferably 100 m / sec.
m / sec or more, more preferably 150 m / sec or more.

Although the linear velocity of the polar solvent when passing through the orifice depends on the pore diameter of the orifice to be used, it cannot be unconditionally determined. Is preferably 100 m / sec or more, more preferably 150 m / sec or more.

In any of the methods, since the dispersion efficiency depends on the processing pressure, the higher the processing pressure, the higher the dispersion efficiency. However, if the processing pressure exceeds 3500 kgf / cm ² , problems are likely to occur in the pressure resistance of the piping of the high-pressure pump and the durability of the apparatus.

In any of the above methods, the number of treatments is not particularly limited, and may be appropriately determined so as to obtain the silica dispersion specified in the present invention. Normally,
It is selected from the range of one to several tens.

[0047]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Reference Examples, Examples, and Comparative Examples, but the present invention is not limited to these Examples.

Various measurements on the silica dispersion were performed as follows.

(Measurement of Average Particle Diameter) Light scattering diffraction type particle size distribution measuring apparatus (manufactured by Coulter, Coulter LS-23)
0) was measured using a volume-based median diameter D _50, employing this value as the average particle size. At the time of measurement, the refractive index of water (dispersion medium) was 1.332 and the refractive index of silica was 1.3.
458 was entered as a parameter.

(Measurement of Viscosity)
The sample was collected in a 00 cc container, and was subjected to 20,000 rpm using a homogenizer (Ultra Turrax T-25, manufactured by Squid).
For 5 minutes. Next, after being immersed in a thermostat at 30 ° C. for 10 minutes, a B-type viscometer (BL, manufactured by Tokimec) was used for 60 minutes.
The viscosity was measured under the condition of rpm.

(Measurement of n Value and Transmittance) The visible light absorption spectrum of the silica dispersion was measured using a spectrophotometer (U.S.
best-35). First, the optical path length 1
Using a 0 mm cell, the reference cell and the sample cell were each filled with ion-exchanged water, and zero point calibration was performed over the entire wavelength range. Next, the concentration of the silica dispersion was 1.5% by weight.
And the diluted dispersion is placed in a sample cell, and the wavelength (λ) is 460 to 760 nm.
The absorbance (τ) in the range of 241 was measured every 1 nm.
The log (λ) and the log (τ) were plotted, and the slope (−n) of the straight line was obtained by the least squares method using the above-described equation (1). The thus obtained n was adopted as the light scattering index.

The transmittance (T) was calculated from the absorbance (τ) at a wavelength of 589 nm (NaD line) by the following equation (2).

T (%) = 10 ^{(2- τ )} (2) (Measurement of zeta potential) The zeta potential of silica particles in a silica dispersion was measured using a laser zeta potentiometer (LE, manufactured by Otsuka Electronics Co., Ltd., LE
ZA-600). First, the silica dispersion was diluted with a 10 ppm aqueous solution of NaCl so that the silica concentration in the silica dispersion was 300 ppm, and the silica dispersion was diluted with an ultrasonic bath.
The dispersion treatment was performed for minutes. Next, the diluent was placed in a measurement cell, and the zeta potential was measured under the conditions of an applied voltage of 80 V, a measurement angle of 20 °, and a measurement temperature of 25 ° C.

Reference Example (Preparation of ground silica dispersion before mixing with cationic resin) Commercially available sodium silicate and pure water were introduced into a reaction vessel so that a solution having a sodium silicate concentration of 5% was formed. . This solution is heated to 40 ° C., and a neutralization reaction is performed to a neutralization rate of 50% using 22 wt% sulfuric acid.
° C. The sulfuric acid described above was added to this reaction solution until the neutralization ratio reached 100%. The filtration and washing operations are repeated on the generated silica, and the dehydrated cake (silica content 15 wt.
%). The specific surface area of the silica obtained by drying the dehydrated cake was 280 m ² / g.

To 2000 g of the dewatered cake, 50 pure water was added.
0 g was added, and premixing was performed by stirring with a propeller mixer to obtain a silica slurry. The obtained paste-form silica slurry was passed through an orifice three times at a processing pressure of 800 kgf / cm ² using a high-pressure homogenizer (manufactured by Nanomizer; Nanomizer, LA-31) to obtain a ground silica dispersion. This is referred to below as the ground silica dispersion (A). Table 1 shows the analysis results.
Shown in

Example 1 To 1000 g of the ground silica dispersion (A) was added 48 g of a 25 wt% aqueous solution of diallyldimethylammonium chloride-acrylamide copolymer as a cationic resin, and the mixture was stirred with a propeller mixer.
A premix was obtained. The obtained pre-mixed solution is subjected to a high-pressure homogenizer (manufactured by Nanomizer, Nanomizer LA-31).
Was passed through the orifice twice at a processing pressure of 800 kgf / cm ² to obtain a cationic resin-modified silica dispersion. Table 1 shows the measurement results of the dispersion.

Example 2 Using a high-pressure homogenizer (manufactured by Nanomizer, Nanomizer LA-31), the premixed liquid was treated at a processing pressure of 800 kgf.
A cationic resin-modified silica dispersion was obtained in exactly the same manner as in Example 1 except that the opposing collision was performed twice at / cm ² . Table 1 shows the measurement results of the dispersion.

Example 3 A cationic resin-modified silica dispersion was obtained in exactly the same manner as in Example 1, except that 60 g of an aqueous solution of diallylamine hydrochloride-sulfur dioxide copolymer having a concentration of 20 wt% was used as the cationic resin. Table 1 shows the measurement results of the dispersion.

Example 4 A cationic resin-modified silica dispersion was obtained in exactly the same manner as in Example 1 except that 43 g of a diallyldimethylammonium chloride polymer aqueous solution having a concentration of 28 wt% was used as the cationic resin. Table 1 shows the measurement results of the dispersion.

Comparative Example 1 Instead of using a high-pressure homogenizer, a homogenizer (Ultra Turrax T-25, manufactured by Squid) was used.
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 1 except that the treatment was performed at 0000 rpm for 10 minutes. Table 1 shows the measurement results of the dispersion.

Comparative Example 2 Instead of using a high-pressure homogenizer, a homogenizer (Ultra Turrax T-25, manufactured by Squid) was used.
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 1 except that the dispersion was treated at 0000 rpm for 60 minutes. Table 1 shows the measurement results of the dispersion.

Comparative Example 3 Instead of using a high-pressure homogenizer, a homogenizer (Ultra Turrax T-25, manufactured by Squid) was used.
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 3, except that the dispersion was treated at 0000 rpm for 10 minutes. Table 1 shows the measurement results of the dispersion.

Comparative Example 4 Instead of using a high-pressure homogenizer, a homogenizer (Ultra Turrax T-25, manufactured by Squid) was used.
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 4 except that the dispersion was treated at 0000 rpm for 10 minutes. Table 1 shows the measurement results of the dispersion.

Example 5 Commercially available sodium silicate and pure water were charged into a reaction vessel such that a solution having a sodium silicate concentration of 5% was formed. This solution was heated to 40 ° C., and a neutralization reaction was performed to a neutralization rate of 50% using 22 wt% sulfuric acid.
Increased to 5 ° C. The sulfuric acid described above was added to the reaction solution until the neutralization ratio reached 100%. The filtration and washing operations are repeated on the generated silica, and the dehydrated cake (silica content 15 wt.
%). The specific surface area of the silica obtained by drying the dehydrated cake was 280 m ² / g.

To 800 g of the dehydrated cake, 200 pure water was added.
g was added and stirred with a propeller mixer to obtain a silica slurry. 48 g of diallyldimethylammonium chloride-acrylamide copolymer aqueous solution having a concentration of 25 wt% as a cationic resin is added to the silica slurry.
In addition, a premixed liquid was obtained by stirring with a propeller mixer. This pre-mixed solution was treated with an orifice at a processing pressure of 800 kgf / cm ² using a high-pressure homogenizer (Nanomizer LA-31, manufactured by Nanomizer).
By passing twice, a cationic resin-modified silica dispersion was obtained. Table 1 shows the measurement results of the dispersion.

Comparative Example 5 Instead of using a high-pressure homogenizer, a homogenizer (Ultra Turrax T-25, manufactured by Squid) was used.
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 5, except that the dispersion was treated at 0000 rpm for 10 minutes. Table 1 shows the measurement results of the dispersion.

[0067]

[Table 1] As can be seen from Table 1, the cationic resin-modified silica dispersions of Examples 1 to 5 all exhibited n values and average particle diameters equal to or greater than those of the pulverized silica dispersion (A). On the other hand, each of the cationic resin-modified silica dispersions of Comparative Examples 1 to 5 had an n value lower than 2.0 and an average particle diameter of 200 nm or more. The dispersions of Comparative Examples 1 to 5 also had lower transmittance than the dispersions of Examples 1 to 5.

Example 6 To 120 g of dry silica having a specific surface area of 300 m ² / g (manufactured by Tokuyama, Leorosil QS30), 880 g of pure water was added, and a homogenizer (manufactured by Squid, Ultra Turrax, T) was used.
-25) to obtain a silica slurry. To this silica slurry, 48 g of an aqueous solution of a diallyldimethylammonium chloride-acrylamide copolymer having a concentration of 25 wt% as a cationic resin was added, and the mixture was stirred with a propeller mixer to obtain a preliminary mixed solution. The resulting premix was passed through an orifice once at a processing pressure of 800 kgf / cm ² using a high-pressure homogenizer (Nanomizer LA-31 manufactured by Nanomizer) to obtain a cationic resin-modified silica dispersion. Table 2 shows the measurement results of the dispersion.

Example 7 800 g of pure water was added to 200 g of dry silica having a specific surface area of 300 m ² / g (manufactured by Tokuyama, Leorosil QS30), and a homogenizer (manufactured by Squid, Ultra Turrax, T) was used.
-25) to obtain a silica slurry. To this silica slurry, 50 g of a 20 wt% aqueous solution of diallylmethylamine hydrochloride polymer as a cationic resin was added at a concentration of 25 wt%, and the mixture was stirred with a propeller mixer to obtain a preliminary mixed solution. The obtained pre-mixed liquid was treated with a high-pressure homogenizer (manufactured by Nanomizer, Nanomizer LA-31) at a processing pressure of 800.
One pass through the orifice at kgf / cm ² gave a cationic resin modified silica dispersion. Table 2 shows the measurement results of the dispersion.

Example 8 Example 7 was repeated except that 20 g of a 50 wt% aqueous solution of polyallylamine hydrochloride polymer was used as the cationic resin.
In the same manner as above, a cationic resin-modified silica dispersion was obtained. Table 2 shows the measurement results of the dispersion.

Example 9 A cationic resin-modified silica dispersion was obtained in exactly the same manner as in Example 7, except that 20 g of an aqueous solution of diallyldimethylammonium chloride polymer having a concentration of 50 wt% was used as the cationic resin. Table 2 shows the measurement results of the dispersion.

Comparative Example 6 Instead of using a high-pressure homogenizer, a homogenizer (Ultra Turrax T-25, manufactured by Squid) was used.
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 6, except that the dispersion was treated at 0000 rpm for 10 minutes. Table 2 shows the measurement results of the dispersion.

Comparative Example 7 Instead of using a high-pressure homogenizer, a homogenizer (Ultra Turrax T-25, manufactured by Squid) was used.
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 7, except that the dispersion was treated at 0000 rpm for 10 minutes. Table 2 shows the measurement results of the dispersion.

Comparative Example 8 Instead of using a high-pressure homogenizer, a homogenizer (Ultra Turrax T-25, manufactured by Squid) was used.
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 8, except that the treatment was performed at 0000 rpm for 10 minutes. Table 2 shows the measurement results of the dispersion.

Comparative Example 9 Instead of using a high-pressure homogenizer, a homogenizer (Ultra Turrax T-25, manufactured by Squid) was used.
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 9, except that the dispersion was treated at 0000 rpm for 10 minutes. Table 2 shows the measurement results of the dispersion.

[0076]

[Table 2] As seen from Table 2, the cationic resin-modified silica dispersions of Examples 6 to 9 all had an average particle diameter of 200 nm.
Or less, and the n value was 2.0 or more. On the other hand, the cationic resin-modified silica dispersions of Comparative Examples 6 to 9 all have an n value of 2.0 or more, but have an average particle diameter of 200 nm.
That was all. The dispersions of Comparative Examples 6 to 9 also had lower transmittance than the dispersions of Examples 6 to 9.

[0077]

As will be understood from the above description, the cationic resin-modified silica dispersion of the present invention is subjected to a cationization treatment even though the dispersed particles are silica fine particles having an average particle diameter of less than 200 nm. It has good dispersibility similar to non-colloidal silica dispersion liquid, so it can be suitably used as a raw material of a coating liquid for inkjet paper, and is also suitably used as a filler in paper such as newsprint. Can be.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08J 3/09 C08J 3/09 C08L 33/24 C08L 33/24 D21H 19/40 D21H 19/40 19/62 19/62 (72) Inventor Yoshinori Tabashi 1-1 Mikage-cho, Tokuyama-shi, Yamaguchi Pref.

Claims (4)

[Claims] 1. A dispersion in which silica and a cationic resin are dispersed in a polar solvent, wherein the silica particles in the dispersion have an average particle diameter of less than 200 nm, and the dispersion has a solid content concentration of less than 200 nm. Light scattering index at 1.5% by weight (n value)
Is 2.0 or more. 2. The cationic resin-modified silica dispersion according to claim 1, wherein the silica is a silica selected from wet silica and dry silica. 3. A mixed solution obtained by mixing silica and a cationic resin in a polar solvent is treated at a processing pressure of 300 kgf / cm.
^{2. The} method for producing a cationic resin-modified silica dispersion according to claim 1, wherein ^two or more collisions are made. 4. A method in which a mixed solution obtained by mixing silica and a cationic resin in a polar solvent is passed through an orifice under a condition that a pressure difference between an inlet and an outlet of the orifice is 300 kgf / cm ² or more. The method for producing a cationic resin-modified silica dispersion according to claim 1.