JP2002302552A - Method for producing cationic resin-modified silica dispersion - Google Patents

Abstract

(57) [Summary] [Problem] The viscosity of a cationic resin-modified silica dispersion obtained is low and has little variation without gelling when mixing and dispersing a dry silica dispersion and a cationic resin aqueous solution. Provided is a method for producing a cationic resin-modified silica dispersion. SOLUTION: While adding a dry silica dispersion liquid at a temperature of 40 ° C. or less to a cationic resin aqueous solution and dispersing it within a temperature range of 20 ° C. to 45 ° C., a dispersion treatment is further performed by a high-pressure homogenizer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating liquid for ink jet recording paper (hereinafter also simply referred to as a coating liquid), a filler for newsprint, an abrasive, and a metal surface treating agent using dry silica. The present invention relates to a novel method for producing a cationic resin-modified silica dispersion useful for the preparation of a silica-based resin. Specifically, it has excellent dispersibility,
An object of the present invention is to provide a method for producing a cationic resin-modified silica dispersion having excellent stability when preparing a coating liquid using the same.

[0002]

2. Description of the Related Art Coating solutions for ink jet recording paper include:
In order to form an ink absorbing layer, inorganic fine powders such as fine particles of silica and alumina are used. Among the fine particles, silica, particularly dry silica, is excellent in dispersibility and is preferably used.

On the other hand, an anionic compound is generally used as an ink for ink-jet, and the ink-absorbing layer having a cationic property is generally used.
This is advantageous for improving the image density and water resistance of the ink jet recording paper.

However, when dry silica is used as the inorganic powder for forming the ink absorbing layer, the particles have an anionic property, which causes a problem in image density and water resistance. Therefore, as a remedy, a cationic resin-modified silica dispersion in which a cationic resin containing a cationic group such as a quaternary ammonium base is mixed with dry silica has been proposed. For example, JP-A-11-321079 discloses A method for producing a cationic resin-modified silica dispersion having a specified mixing method, which includes a step of adding a dry silica dispersion to a cationic resin aqueous solution and mixing the same.

Further, as a metal surface treating agent, a treating agent in which a cationic resin is mixed with a silica dispersion liquid in order to improve the corrosion resistance of the metal and the adhesion of the paint has been proposed. JP-A-24470 discloses a method in which water-dispersible colloidal silica is added to a cationic resin aqueous solution while stirring.

[0006]

However, in such a method of preparing a silica dispersion in which silica powder is dispersed in water in advance and then mixing it with an aqueous solution of a cationic resin, the silica powder is dispersed in water. When a silica dispersion having an increased liquid temperature due to stirring heat generated during the addition is added to the aqueous solution of the cationic resin, the silica particles are aggregated, causing a problem that the entire cationic resin-modified silica dispersion is gelled. Was.

In addition, even if the silica dispersion at room temperature is mixed and dispersed while being added to the aqueous solution of the cationic resin, if the temperature at the time of the dispersion is high, the resulting dispersion of the silica-modified cationic resin gels, When the temperature at the time of dispersing is low, the viscosity of the obtained cationic resin-modified silica dispersion becomes high, such as the viscosity of the obtained cationic resin-modified silica dispersion becomes high, and the handling of the cationic resin-modified silica dispersion becomes extremely difficult. There was also a problem that it became difficult.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, a dispersion (hereinafter referred to as a primary dispersion) in which dry silica fine particles are dispersed in water (hereinafter, referred to as primary dispersion) in advance. , Dry silica dispersion) at a temperature of 40 ° C.
The liquid temperature (hereinafter, referred to as secondary dispersion temperature) at the time of mixing / dispersion (hereinafter, referred to as secondary dispersion) while being added to the cationic resin aqueous solution while maintaining the temperature below is a temperature of 20 ° C to 45 ° C. By further treating the dispersion obtained by controlling the dispersion within the range (hereinafter referred to as a secondary dispersion) with a high-pressure homogenizer, it was found that a very stable cationic resin-modified silica dispersion can be obtained. Was completed.

That is, the present invention provides a method of adding a dry silica dispersion at 40 ° C. or lower to an aqueous solution of a cationic resin,
This is a method for producing a cationic resin-modified silica dispersion, which comprises dispersing within a temperature range of 0 ° C. to 45 ° C., and further performing a dispersion treatment using a high-pressure homogenizer.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The dry silica powder used in the present invention is obtained by burning a silane gas such as silicon tetrachloride in an oxyhydrogen flame, which is also called "fumed silica". Used without restrictions.

Generally, fumed silica has a specific surface area of 30 to
Those having a range of 500 m ² / g are available, and these fumed silicas can be suitably used in the present invention.

The cationic resin used in the present invention is not particularly limited as long as it dissociates when dissolved in water to exhibit cationic properties, and known cationic resins can be used without any particular limitation.

Among them, a resin having a primary to tertiary amine group or a quaternary ammonium group can be preferably used. Specific examples include polyethyleneimine, polyvinylpyridine, polyamine sulfone, polydialkylaminoethyl methacrylate, polydialkylaminoethyl acrylate, polydialkylaminoethyl methacrylamide, polydialkylaminoethyl acrylamide, polyepoxyamine, polyamideamine, dicyandiamide. -Formalin condensate, dicyandiamide polyalkyl-polyalkylene polyamine condensate, polyvinylamine, polyallylamine and other compounds and their hydrochlorides, furthermore, polydiallyldimethylammonium chloride and its copolymers such as acrylamide, diallylmethylamine hydrochloride polymerization Products, polymethacrylic acid ester methyl chloride quaternary salt, and the like.

In the present invention, an organic polar solvent may be mixed with the aqueous solution of the cationic resin, if necessary. Examples of such organic polar solvents include methanol, ethanol, alcohols such as isopropyl alcohol, ethers,
And ketones.

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

In the present invention, the aqueous dispersion of the cationic resin is secondarily dispersed in a temperature range of 20 ° C. to 45 ° C. while adding a dry silica dispersion at a temperature of 40 ° C. or less.

Since dry silica is obtained in the form of a dry powder in the production process, it is necessary to obtain a dry silica dispersion by dispersing dry silica in water. When the dry silica is dispersed in water, stirring heat is generated by stirring, and the temperature of the dry silica dispersion increases. The heat of stirring varies depending on the type of disperser, dispersion time, and silica concentration in the dispersion.

When the temperature of the silica dispersion increased by the heat of stirring exceeds 40 ° C., even if the secondary dispersion temperature is controlled to 45 ° C., a phenomenon that the entire secondary dispersion becomes a gel occurs,
It is difficult to redistribute. Although the inventors of the present invention cannot clearly explain the cause, it is attempted to mix and disperse the silica dispersion while adding it to a cationic resin aqueous solution in a state of having a latent heat at a liquid temperature of 40 ° C. without cooling. Then
Even if the secondary dispersion temperature is controlled to 45 ° C., before the heat exchange by the cooling device is performed, the temperature of the secondary dispersion liquid temporarily rises due to heat of stirring, and locally exceeds 45 ° C., It is presumed that the silica particles started to aggregate.

The dry silica dispersion may be cooled to 40 ° C. or lower by dispersing the dry silica powder in water and then cooling the dry silica dispersion heated to 40 ° C. or higher to 40 ° C. or lower; The dispersion may be performed while controlling the temperature of the dry silica dispersion during the primary dispersion to 40 ° C. or lower.

In the present invention, the secondary dispersion temperature is 20 ° C.
To 45 ° C, and even 25 ° C to 40 ° C.
It is preferable to control the temperature in a temperature range of ° C.

The higher the secondary dispersion temperature is, the lower the viscosity of the secondary dispersion becomes. However, if the temperature exceeds 45 ° C., the silica particles in the secondary dispersion tend to aggregate, and the viscosity of the secondary dispersion increases rapidly. The secondary dispersion tends to gel. When the secondary dispersion temperature is lower than 20 ° C., the viscosity of the secondary dispersion tends to increase. Although the present inventors cannot clearly explain the cause, it is presumed that if the temperature of the secondary dispersion is less than 20 ° C., the dispersibility of the dry silica and the cationic resin in the dispersion is reduced. Further, in the present invention, the secondary dispersion is treated with a high-pressure homogenizer to obtain a cationic resin-modified silica dispersion, but the higher the viscosity of the secondary dispersion, the higher the cationic dispersion obtained by treatment with a high-pressure homogenizer. The viscosity of the resin-modified silica dispersion also tends to increase. It is not preferable that the viscosity of the cationic resin-modified silica dispersion liquid be high, because the handleability in the subsequent manufacturing process is reduced.

Various phenomena due to temperature control of the dry silica dispersion and the secondary dispersion are remarkably observed when the silica concentration in the dry silica dispersion is 15% or more.
The present invention is more effective when the silica concentration is 15% or more.

The method of controlling the secondary dispersion temperature in the temperature range of 20 ° C. to 45 ° C. is not particularly limited, but is not particularly limited.
It is preferable to control the temperature to be an arbitrary constant temperature in a temperature range of 5 ° C.

In the present invention, the disperser used for the primary dispersion and the secondary dispersion is not particularly limited, but a general stirrer having a propeller blade, a turbine blade, a paddle blade, a high-speed rotating centrifugal radial stirrer such as a disper mixer, a homogenizer, a homogenizer, and the like. Examples include a high-speed rotary shear type stirrer such as a mixer and an ultra mixer, and an emulsifier such as a colloid mill and a planetary mixer.

The silica concentration in the dry silica dispersion is 15%
When efficiently obtaining a high concentration of dry silica dispersion liquid,
In addition, when mixing and dispersing while adding the dry silica dispersion having a silica concentration of 15% or more to the aqueous cationic resin solution, among the above dispersers, a disperser having a strong shear force is preferable. Specifically, a high-speed rotary shear type stirrer, a composite type disperser in which a high-speed rotary shear type stirrer is further combined with a propeller blade and a paddle blade, a planetary mixer and a high-speed rotary centrifugal radial type stirrer or a high-speed rotary shear type stirrer are combined. Composite dispersing machine.

The viscosity of the cationic resin-modified silica dispersion is determined by the specific surface area of dry silica as a raw material, the structure and molecular weight of the cationic resin, the content of dry silica and the cationic resin in the dispersion, and their respective mixing ratios. It also largely depends on the type of disperser used for dispersion.

In the present invention, the amounts of the dry silica and the cationic resin in the cationic resin-modified silica dispersion are not particularly limited, but the amount of the dry silica in the cationic resin-modified silica dispersion is 10 to 45% by weight, Furthermore, 15-40
% Is preferable, and the amount of the cationic resin is 1 to 50 parts by weight, more preferably 3 to 50 parts by weight, per 100 parts by weight of the dry silica.
10 parts by weight are preferred.

When the concentration of the dry silica in the cationic resin-modified silica dispersion is more than 45% by weight, the dispersion of the dry silica can be reduced even if a disperser having a strong shearing force is used during secondary dispersion. May be difficult to mix with the aqueous cationic resin solution. When the amount is less than 10% by weight, it is difficult to form a coating layer having a sufficient thickness by one coating in the coating step after preparing the coating liquid, or energy efficiency in drying after coating. There is a problem such as worsening.

When the amount of the cationic resin in the cationic resin-modified silica dispersion is adjusted to be less than 1 part by weight based on 100 parts by weight of the dry silica,
The balance of the surface charge of the fumed silica particles becomes uneven,
The silica particles tend to cause strong aggregation. Further, when the amount of the cationic resin is adjusted to be more than 50 parts by weight with respect to 100 parts by weight of silica, the viscosity may be increased and the dispersion treatment may be difficult.

In the present invention, the higher the zeta potential as an index of the surface charge of the particles in the cationic resin-modified silica dispersion, the higher the water resistance of the obtained ink jet recording paper, and is generally +10 mV or more. ,
Preferably at least +20 mV, more preferably +30 mV
It is preferably at least V.

The above-mentioned zeta potential can be increased by adjusting the amount of the cationic resin to be mixed.
Since the range of increase in the zeta potential varies depending on the type of the cationic resin to be mixed, it is preferable to select an optimal amount to be added from the above amount by an experiment in advance.

In the present invention, the secondary dispersion obtained by mixing and dispersing the dry silica dispersion and the aqueous cationic resin solution by the above method is then subjected to a dispersion treatment using a high-pressure homogenizer, whereby the dispersion is extremely excellent. Thus, a cationic resin-modified silica dispersion having excellent stability when preparing a coating liquid using the same is obtained.

As the high-pressure homogenizer, those having a known structure can be used without any particular limitation. Typical examples thereof include trade names of Nanomizer; trade names of Nanomizer and Microfluidics; Examples include a microfluidizer and an Sugino machine-made optimizer.

Using the above high-pressure homogenizer, the secondary dispersion liquid is caused to collide with the processing liquid at a processing pressure of 300 kgf / cm ² or more, or under a condition that the differential pressure between the inlet side and the outlet side of the orifice is 300 kgf / cm ² or more. By passing through an orifice, a cationic resin-modified silica dispersion having an average agglomerated particle size in a suitable range can be obtained.

The degree of dispersion by the high-pressure homogenizer is preferably such that the average agglomerated particle diameter in the resulting cationic resin-modified silica dispersion is in the range of 10 to 1000 nm, preferably 50 to 300 nm. .

That is, when the average agglomerated particle size is smaller than 10 nm, the viscosity of the cationic resin-modified silica dispersion becomes high, and for example, when it is used as a coating liquid for ink jet recording paper, it may be difficult to handle. Average particle size is 1000n
When it is larger than m, the dry silica may settle in the cationic resin-modified silica dispersion liquid and phase separation may be easily caused.

[0037]

According to the method of the present invention, a secondary dispersion obtained by mixing and dispersing a dry silica dispersion and a cationic resin aqueous solution is not gelled, and the cationic resin-modified silica dispersion is not gelled. Can be obtained. Further, the obtained cationic resin-modified silica dispersion is characterized in that the viscosity is low and the dispersion is small.

Further, a cationic resin-modified silica dispersion having a high dry silica concentration can be easily obtained.

[0039]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited by these examples.

The physical properties of the cationic resin-modified silica dispersion were measured by the following methods.

(Measurement of Average Particle Diameter) After diluting the cationic resin-modified silica dispersion with ion-exchanged water so that the concentration of the dispersion becomes 10% by weight, a light scattering diffraction type particle size distribution analyzer ( Coulter, Coulter LS-230)
It was used to measure the volume-based arithmetic mean diameter D _50, employing this value as an average diameter.

At the time of measurement, 1.3332 of water (dispersion medium) and 1.458 of silica were input as parameters.

(Viscosity measurement) 300 g of the secondary dispersion or the cationic resin-modified silica dispersion was placed in a 500 cc container, and the mixture was homogenized (Ultra Turrax T-Made by Squid).
Using 25), the mixture was stirred at 20,000 rpm for 5 minutes. Next, after being immersed in a thermostat at 30 ° C. for 10 minutes, the viscosities of the secondary dispersion and the cationic resin-modified silica dispersion were measured at 60 rpm using a B-type viscometer (manufactured by Tokimec, BL).

(Measurement of Zeta Potential) The zeta potential of the silica particles in the cationic resin-modified silica dispersion was measured using a laser zeta potentiometer (LEZA-600, manufactured by Otsuka Electronics Co., Ltd.). First, the silica concentration in the silica dispersion was set to 300
The solution was diluted with a 10 ppm aqueous solution of NaCl so as to be 1 ppm, and dispersed in an ultrasonic bath for 5 minutes. Next, the diluent was put into a measurement cell, and measurement was performed under the conditions of an applied voltage of 80 V, a measurement angle of 20 °, and a measurement temperature of 25 ° C.

Example 1 400 g of fumed silica having a specific surface area of 140 m ² / g (manufactured by Tokuyama, Leolosil QS-10) was added to pure water 160
0 g, and dispersed with a homogenizer (Ultra Turrax T-25, manufactured by Squid) to obtain a dry silica dispersion. The liquid temperature of the dry silica dispersion was 49 ° C. After cooling the dry silica dispersion to 35 ° C., the liquid temperature was maintained at 40 ° C. while adding the dry silica dispersion to 33 g of an aqueous diallylmethylamine hydrochloride polymer solution having a cationic resin concentration of 60% at room temperature. Then, secondary dispersion was obtained by dispersing with a homogenizer (Ultra Turrax T-25, manufactured by Squid). The liquid temperature of the secondary dispersion is 39 ° C.
Met. The secondary dispersion is subjected to dispersion treatment by passing through an orifice once at a processing pressure of 800 kgf / cm ² using a high-pressure homogenizer (manufactured by Nanomizer, Nanomizer, LA-31) to obtain a cationic resin-modified silica dispersion. Was. Table 1 shows the physical properties of the resulting cationic resin-modified silica dispersion and secondary dispersion.

Example 2 400 g of fumed silica having a specific surface area of 300 m ² / g (manufactured by Tokuyama, Leolosil QS-30) was added to pure water 160
0 g, and dispersed with a homogenizer (Ultra Turrax T-25, manufactured by Squid) to obtain a dry silica dispersion. The liquid temperature of the dry silica dispersion was 50 ° C. After cooling the dry silica dispersion to 35 ° C., the liquid temperature was maintained at 40 ° C. while adding the dry silica dispersion to 48 g of an aqueous diallyldimethylammonium chloride polymer solution having a cationic resin concentration of 25% at room temperature. , Homogenizer (Ultra Turrax T-25, made by Squid)
To obtain a secondary dispersion. The liquid temperature of the secondary dispersion was 40 ° C. This secondary dispersion is subjected to a high-pressure homogenizer (manufactured by Nanomizer, Nanomizer, LA-31).
At a treatment pressure of 800 kgf / cm ² to perform a dispersion treatment by passing through an orifice once to obtain a cationic resin-modified silica dispersion. Table 1 shows the physical properties of the resulting cationic resin-modified silica dispersion and the secondary dispersion.

Example 3 400 g of fumed silica having a specific surface area of 300 m ² / g (manufactured by Tokuyama, Leolosil QS-30) was added to pure water 160
0 g, and dispersed with a homogenizer (Ultra Turrax T-25, manufactured by Squid) while maintaining the liquid temperature at 30 ° C., to obtain a dry silica dispersion. The liquid temperature of the dry silica dispersion was 30 ° C. While adding this dry silica dispersion to 48 g of a diallyldimethylammonium chloride polymer aqueous solution having a cationic resin concentration of 25% at room temperature, the liquid temperature was maintained at 30 ° C., and a homogenizer (Ultra Turrax T-25, manufactured by Squid) was used. To obtain a secondary dispersion. The liquid temperature of the secondary dispersion was 30 ° C. The secondary dispersion is subjected to dispersion treatment by passing through an orifice once at a processing pressure of 800 kgf / cm ² using a high-pressure homogenizer (manufactured by Nanomizer, Nanomizer, LA-31) to obtain a cationic resin-modified silica dispersion. Was. Table 1 shows the physical properties of the resulting cationic resin-modified silica dispersion and secondary dispersion.

Comparative Example 1 400 g of fumed silica having a specific surface area of 140 m ² / g (manufactured by Tokuyama, Leolosil QS-10) was mixed with pure water 160
0 g, and dispersed with a homogenizer (Ultra Turrax T-25, manufactured by Squid) to obtain a dry silica dispersion. The liquid temperature of the dry silica dispersion was 51 ° C. Without cooling this dry silica dispersion and without controlling the secondary dispersion temperature, the cationic resin concentration at room temperature was 60%.
Was dispersed with a homogenizer (Ultra Turrax T-25, manufactured by Squid) while being added to 33 g of an aqueous diallylmethylamine hydrochloride polymer solution, and the entire secondary dispersion gelled during the addition of the dry silica dispersion, and was dispersed. Became impossible. The temperature at the time of gelation was 52 ° C.

Comparative Example 2 400 g of fumed silica having a specific surface area of 300 m ² / g (manufactured by Tokuyama, Leolosil QS-30) was added to pure water 160
0 g, and dispersed with a homogenizer (Ultra Turrax T-25, manufactured by Squid) to obtain a dry silica dispersion. The liquid temperature of the dry silica dispersion was 50 ° C. Without cooling this dry silica dispersion and without controlling the secondary dispersion temperature, the cationic resin concentration at room temperature was 25%.
Was dispersed in a homogenizer (Ultra Turrax T-25, manufactured by Squid) while being added to 48 g of the diallyldimethylammonium chloride polymer aqueous solution of the above. As a result, the entire secondary dispersion gelled during the addition of the dry silica dispersion, and was not dispersed. It has become possible. The temperature at the time of gelation was 51 ° C.

Comparative Example 3 400 g of fumed silica having a specific surface area of 300 m ² / g (manufactured by Tokuyama, Leolosil QS-10) was added to pure water 160
0 g, and dispersed with a homogenizer (Ultra Turrax T-25, manufactured by Squid) to obtain a dry silica dispersion. The liquid temperature of the dry silica dispersion was 50 ° C. After cooling this dry silica dispersion to 35 ° C., the dry silica dispersion was added to 48 g of an aqueous diallyldimethylammonium chloride polymer solution having a cationic resin concentration of 25% at room temperature while adding a homogenizer (Ultra Turrax T, manufactured by Squid). -25). After the whole amount of the dry silica dispersion was added, the dispersion temperature was kept at 55 ° C., and the dispersion was continued. As a result, the whole secondary dispersion gelled, and the dispersion became impossible.

Comparative Example 4 400 g of fumed silica having a specific surface area of 140 m ² / g (manufactured by Tokuyama, Leolosil QS-10) was added to pure water 160
0 g, and dispersed with a homogenizer (Ultra Turrax T-25, manufactured by Squid) to obtain a dry silica dispersion. The liquid temperature of the dry silica dispersion was 50 ° C. After cooling the dry silica dispersion to 15 ° C., the liquid temperature was maintained at 15 ° C. while adding the dry silica dispersion to 33 g of an aqueous diallylmethylamine hydrochloride polymer solution having a cationic resin concentration of 60% at room temperature. Then, secondary dispersion was obtained by dispersing with a homogenizer (Ultra Turrax T-25, manufactured by Squid). The liquid temperature of the secondary dispersion is 16 ° C
Met. The secondary dispersion is subjected to dispersion treatment by passing through an orifice once at a processing pressure of 800 kgf / cm ² using a high-pressure homogenizer (manufactured by Nanomizer, Nanomizer, LA-31) to obtain a cationic resin-modified silica dispersion. Was. Table 1 shows the physical properties of the resulting cationic resin-modified silica dispersion and the secondary dispersion.

Comparative Example 5 400 g of fumed silica having a specific surface area of 300 m ² / g (manufactured by Tokuyama, Leolosil QS-10) was mixed with pure water 160
0 g, and dispersed with a homogenizer (Ultra Turrax T-25, manufactured by Squid) to obtain a dry silica dispersion. The liquid temperature of the dry silica dispersion was 50 ° C. After cooling the dry silica dispersion to 15 ° C., the liquid temperature was maintained at 15 ° C. while adding the dry silica dispersion to 48 g of an aqueous diallyldimethylammonium chloride polymer solution having a cationic resin concentration of 25% at room temperature. , Homogenizer (Ultra Turrax T-25, made by Squid)
To obtain a secondary dispersion. The liquid temperature of the secondary dispersion was 15 ° C. This secondary dispersion is subjected to a high-pressure homogenizer (manufactured by Nanomizer, Nanomizer, LA-31).
And a dispersion treatment was performed by passing through an orifice once at a treatment pressure of 800 kgf / cm ² to obtain a cationic resin-modified silica dispersion. Table 1 shows the physical properties of the resulting cationic resin-modified silica dispersion and secondary dispersion.

[0053]

[Table 1]

As can be seen from Table 1, the gel was obtained by mixing and dispersing the dry silica dispersion cooled to 40 ° C. or less within the temperature range of 20 ° C. to 45 ° C. while adding the dispersion to the aqueous cationic resin solution. Thus, a stable secondary dispersion liquid was obtained.

Further, at the time of preparation of the secondary dispersion, the temperature is lowered from 20 ° C.
The cationic resin-modified silica dispersions obtained in Examples 1, 2 and 3 whose temperature was controlled in a temperature range of 15 ° C. were 15 ° C.
The viscosity of the dispersion was lower than that of the cationic resin-modified silica dispersions obtained in Comparative Examples 4 and 5 in which the temperature was controlled. Further, in Comparative Example 3 in which the secondary dispersion temperature was 55 ° C., the secondary dispersion liquid gelled.

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Claims (1)

[Claims] 1. A dispersion treatment using a high-pressure homogenizer after adding a dry silica dispersion liquid at a temperature of 40 ° C. or less to a cationic resin aqueous solution and dispersing it in a temperature range of 20 ° C. to 45 ° C. A method for producing a cationic resin-modified silica dispersion.