JP2001207078A - Cationic resin modified silica dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a cationic resin modified silica dispersion excellent in dispersion stability and the performance of a coating liquid, or the like, prepared therefrom, which is suitable as an inner filler, or the like, of coating liquids for recording paper for ink-jet, abrasives, and news paper, or the like, and to provide a method of its manufacture. SOLUTION: This cationic resin modified silica dispersion is a dispersion prepared by dispersing a silica and a cationic resin in a polar solvent containing the silica at 10-30 wt.% concentration, and its has 50% or less increase in viscosity after 1 hour, when 8 mmol potassium hydroxide is added to 1 kg of the dispersion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersion of a cationic resin-modified silica useful for preparing a coating liquid for ink jet recording paper (hereinafter also simply referred to as a coating liquid), a filler for newsprint, an abrasive and the like. Liquid. Specifically, it has excellent dispersion stability,
Provided are a cationic resin-modified silica dispersion having excellent performance when a coating liquid is prepared using the same, and a method for producing 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. On the other hand, as the ink for ink jet, an anionic compound is generally used in many cases, and the ink absorbing layer having a cationic property is used for improving the image density and water resistance of the ink jet recording paper. Is advantageous.

[0003] However, when silica is used as the inorganic powder for forming the ink absorbing layer, there is a problem in image density and water resistance because the silica is anionic. There has been proposed a cationic resin-modified silica dispersion in which a cationic resin containing a cationic group such as above is blended.

For example, when a cationic resin is mixed with a silica dispersion in which fine silica particles are dispersed, the silica particles tend to agglomerate. However, when the cationic resin is treated with a disperser having a strong shearing force, a stable cationic resin is obtained. The present inventors have already proposed that a resin-modified silica dispersion can be obtained (Japanese Patent Application No. 10-375515).

[0005]

However, the cationic resin-modified silica dispersion is generally used at a silica concentration of 10 to 30% by weight when a coating liquid is prepared, and the silica is used as a binder. By adding various additives in addition to the water-soluble polymer, a stable coating liquid can be reproducibly produced due to differences in the raw silica used for the production of the cationic resin-modified silica dispersion and the production conditions of the dispersion. There was a problem that it was difficult to prepare well.

Accordingly, an object of the present invention is to provide a cationic resin-modified silica dispersion having excellent dispersion stability, which enables a stable coating liquid to be prepared with good reproducibility, and a method for producing the same. is there.

[0007]

Means for Solving the Problems The present inventors have intensively studied the above problems. As a result, they have found that the stability of the dispersion is affected by the degree of reaction between the silanol groups on the silica surface and the cationic resin. As a result of further study based on such findings, the cationic resin-modified silica dispersion in which the cationic resin is present together with the silica particles, for a specific temperature range and a specific period,
By aging, it was possible to obtain a cationic resin-modified silica dispersion which is extremely stable against a change in pH, and particularly excellent in stability against a change in the state of a liquid at the time of preparing a coating liquid. Was completed.

That is, the present invention relates to a dispersion liquid comprising silica and a cationic resin dispersed in a polar solvent, wherein
At a concentration of 0 to 30% by weight, and at 30 ° C., an increase rate of the viscosity of 1 hour after adding 8 mmol of potassium hydroxide to 1 kg of the dispersion is 50%
It is a cationic resin-modified silica dispersion characterized by the following.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The silica used in the present invention is not particularly limited, and may be dry silica, wet silica, or sol-gel.
Known silica such as gel silica and colloidal silica can be used as a raw material.

The fumed silica is obtained by burning a silane-based gas such as silicon tetrachloride in an oxyhydrogen flame, and is also called “fumed silica”. In general,
Dry silica having a specific surface area in the range of 30 to 500 m ² / g is available and can be suitably used in the present invention.

As the coating liquid for ink jet recording paper, silica having a specific surface area of 200 to 400 m ² / g is particularly preferable because of its high ink absorbing ability.

The wet silica is typically a silica obtained by a precipitation method of precipitating silica in a solution by neutralizing sodium silicate with a mineral acid, and is also called white carbon. Similarly, gel silica produced by neutralizing sodium silicate with an acid can also be used.

As the above wet process silica, a dehydrated silica cake which is not subjected to a drying step after filtration and washing after the neutralization reaction can be directly used.

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

Furthermore, the above-mentioned colloidal silica is generally obtained by passing an aqueous solution of sodium silicate through a cation exchange resin to form a silica sol, followed by heating and aging to grow particles.

The silica in the silica dispersion of the present invention preferably has an average primary particle size in the range of 1 to 50 nm and an average aggregated particle size in the range of 10 to 1000 nm.
The silica dispersion in the above range has several primary silica particles to
Since it is composed of agglomerated particles that are agglomerated by thousands, it has excellent ink absorbing ability when used in a coating liquid, and can be suitably used in fields such as ink jet recording paper.

That is, when the average primary particle diameter of silica is smaller than 1 nm, the silica may be unstable or the ink absorbing ability may be low. If it is larger than 50 nm, the ink absorbing ability may be reduced.

The above silica has an average agglomerated particle diameter of 10 to 1
A range of 000 nm, preferably a range of 50 to 300 nm, is preferred. When the average aggregated particle diameter is smaller than 10 nm, the viscosity of the cationic resin-modified silica dispersion becomes high, and it may be difficult to handle as a coating liquid. If the average particle size is larger than 1000 nm, silica may precipitate in a coating liquid and phase separation may be easily caused.

In order to prepare a slurry in which silica having the above-mentioned average agglomerated particle diameter is finely dispersed, a dispersing machine such as a high-pressure homogenizer such as a nanomizer described below can be effectively used.

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, resins 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, compounds such as polyallylamine and their hydrochlorides, further copolymers such as polydiallyldimethylammonium chloride and its acrylamide, polydiallylmethylamine hydrochloride And polymethacrylic acid ester methyl chloride quaternary salt.

The polar solvent used in the present invention is not particularly limited as long as it is a polar solvent in which silica and the cationic resin are easily dispersed. Water is most preferred as such a polar solvent. Of course, besides water, methanol, ethanol, alcohols such as isopropyl alcohol, ethers,
A polar solvent such as a ketone can be used, and a mixed solvent of water and the above polar solvent can also be suitably 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 as long as the effects of the present invention are not impaired.

In the present invention, the concentration of silica in the cationic resin-modified silica dispersion is in the range of 10 to 30% by weight, preferably 10 to 25% by weight, and the amount of the cationic resin is 100 parts by weight of silica. And 3 to 50 parts by weight, particularly preferably 3 to 10 parts by weight.

That is, when the concentration of silica in the silica dispersion is 3
If it is more than 0% by weight, mixing with the cationic resin may be difficult. If less than 10% by weight,
When a coating solution is prepared, there are problems such as difficulty in forming a coating layer having a sufficient thickness by one coating, and poor energy efficiency when drying after coating.

If the amount of the cationic resin in the silica dispersion is less than 3 parts by weight with respect to 100 parts by weight of the silica, the balance of the surface charges of the silica particles becomes uneven,
Silica particles tend to cause strong aggregation.
On the other hand, when the amount of the cationic resin is more than 50 parts by weight based on 100 parts by weight of silica, the viscosity becomes high, and the dispersion treatment may become difficult.

In the present invention, the zeta potential as an index of the surface charge of the particles in the cationic resin-modified silica dispersion is preferably +10 mV or more, and more preferably +10 mV, in order to increase the water resistance of the obtained ink jet recording paper. +
It is preferably at least 20 mV, more preferably at least +30 mV. The zeta potential can be adjusted higher by increasing the mixing amount of the cationic resin.However, since the increase in the zeta potential varies depending on the type of the cationic resin to be mixed, the optimum addition amount is determined in advance by experiments. It is preferable to select from the above addition amounts.

In the present invention, the dispersion method for producing the cationic resin-modified silica dispersion is not particularly limited, but it can be suitably produced by the following dispersion method.

At this time, silica may be used in the form of powder or silica slurry finely dispersed in a polar solvent such as water in advance.

As the dispersion method, a polar solvent, silica, and a cationic resin are mixed, and then mixed with a turbine / stator type high-speed rotary stirring / dispersing machine such as a homogenizer, a colloid mill, an ultrasonic emulsifier, a high-pressure homogenizer, or the like. For finely dispersing and mixing. Among the above, a high-pressure homogenizer can be most preferably employed.

Specific examples of typical high-pressure homogenizers include trade names of Nanomizer; trade names of Nanomizer and Microfluidics; microfluidizers; and Artimizer of Sugino Machine. Using the above high-pressure homogenizer, a mixed solution obtained by mixing a polar solvent, silica and a cationic resin is opposed to each other at a processing pressure of 300 kgf / cm ² or more, or a differential pressure between the inlet side and the outlet side of the orifice is 300 kgf. By passing through an orifice under the condition of / cm ² or more, a cationic resin-modified silica dispersion having an average agglomerated particle size in a suitable range can be obtained.

By the way, the present inventors have found that the stability of the cationic resin-modified silica dispersion and the properties of the dispersion as a coating liquid are greatly affected by the type of silica used and its history. In particular, in the case of fumed silica, it has been found that the properties of the dispersion are affected by the density of surface silanol groups that change with the history.

That is, when silica and a cationic resin are mixed in a polar solvent, a silanol group on the silica surface, ie, an acid point, reacts with a cationic group of the cationic resin, ie, a base point,
It is considered that the acid site and the base site cause an ionic bonding reaction to form a relatively strong bond.

Therefore, the stability of the dispersion depends on the degree of the reaction between the silanol groups on the silica surface and the cationic resin, and when the bonding is insufficient, the viscosity of the dispersion increases. It is considered something.

The present invention has been made based on the above-mentioned findings, and the dispersion 1 is measured at the silica concentration at 30 ° C. of the cationic resin-modified silica dispersion.
A cationic resin-modified silica dispersion characterized in that the rate of increase in viscosity one hour after the addition of 8 mmol of potassium hydroxide per kg is 50% or less.

Here, the rate of increase in viscosity U (%) is determined by the initial viscosity (A (mPa · s)) of the silica dispersion and the viscosity (B (mPa · s)) one hour after the addition of potassium hydroxide. And the value obtained by the following formula.

U = ((B−A) / A) × 100

When the cationic resin-modified silica dispersion of the present invention uses, for example, a quaternary ammonium salt compound such as polydiallyldimethylammonium chloride or a hydrochloride of polyallylamine as the cationic resin, the pH of the silica dispersion is It often exhibits an acidity in the range of 2-4. Generally, the pH of an aqueous dispersion of fumed silica is about 4, but
When mixed with a quaternary ammonium salt compound or hydrochloride, a phenomenon is seen in which the pH is lowered because hydrochloric acid is liberated by the reaction between the silanol group and the cationic group.

On the other hand, in the cationic resin-modified silica dispersion, the cationic resin ion-bonded to the silica surface is released again from the silica surface when the pH is changed by adding an alkali, and as a result, silica aggregation occurs, It is considered that the viscosity of the silica dispersion increases.

Therefore, it can be said that the cationic resin-modified silica dispersion of the present invention which does not gel for a long time even when the silica dispersion is shifted to the alkali side has extremely high stability against pH fluctuation. .

In the present invention, in order to produce a stable cationic resin-modified silica dispersion as described above, it is important to age the silica dispersion in the presence of the cationic resin.

The aging conditions include the type of silica used,
Depends on the condition. For example, fumed silica is obtained by burning a silane-based gas such as silicon tetrachloride in an oxyhydrogen flame.
It is about 1 to 3 per square angstrom. Thus, for silica with few silanol groups on the surface,
A treatment in which the aging time is relatively long is recommended.

That is, in the present invention, the silica is dry silica, and after the dry silica is dispersed in a polar solvent together with a cationic resin, the dispersion is dried at 5 to 45 ° C., preferably 15 to 40 ° C.
A method for producing a cationic resin-modified silica dispersion, characterized by aging at a temperature in the range of 10 days or more.

When the above-mentioned dry silica is used as a raw material, the silica is subjected to a humidification treatment or the silica is dispersed in a polar solvent containing water so that the silica has a surface silanol group density of 100%. It is preferable to preliminarily adjust the number of the cationic resin-modified silica dispersion to be more than 4 per square angstrom because the aging period can be shortened and the stability of the cationic resin-modified silica dispersion can be increased.

That is, according to the present invention, after the humidifying treatment is performed so that the surface silanol group density of the dry silica exceeds 4 per 100 square angstroms, the silica is dispersed together with a cationic resin in a polar solvent, and then dried at 5 to 45 ° C. A method for producing a cationic resin-modified silica dispersion, which is preferably aged for at least 7 days at a temperature in the range of 15 to 40 ° C., and wherein the silica is dry silica, and the dry silica contains water. After dispersing in a polar solvent and adjusting the surface silanol group density to exceed 4 per 100 square angstroms, the cationic resin is dispersed, and then in a range of 5 to 45 ° C, preferably 15 to 40 ° C. A process for producing a cationic resin-modified silica dispersion, which is performed by aging at a temperature of 5 days or more.

The silica such as the wet silica, the sol-gel silica, and the colloidal silica can be obtained by dispersing dry silica in a polar solvent containing water and adjusting the surface silanol group density to approximately the same as that obtained when the silica is adjusted. And a cationic resin dispersed therein, and then 5 to 4
The desired cationic resin-modified silica dispersion can be obtained by aging at a temperature of 5 ° C, preferably 15 to 40 ° C for 5 days or more.

In the present invention, the aging of the cationic resin-modified silica dispersion exhibits a sufficient effect in the aging time described above. In particular, the aging is carried out by heating the dispersion at a temperature of 30 to 70 ° C. The ripening time can be greatly reduced irrespective of the type of silica.

That is, according to the present invention, silica is dispersed in a polar solvent together with a cationic resin.
There is also provided a method for producing a cationic resin-modified silica dispersion, which comprises aging by heating at a temperature of 70 ° C.

The heat treatment temperature is preferably from 40 to
The temperature is preferably 70 ° C., particularly more than 45 ° C. and 60 ° C. or less.

By aging under the above conditions, the silanol groups on the silica surface and the cationic resin react uniformly, and a stable cationic resin-modified silica dispersion can be obtained.

In the method for producing a cationic resin-modified silica dispersion of the present invention, if the aging temperature is less than 5 ° C., the aging time may be longer, which is not industrial. Further, when the aging temperature exceeds 45 ° C., there is a concern that the polar solvent is vaporized and the silica dispersion is deteriorated. Therefore, when aging is performed at such a temperature, the aging time is too long. It is recommended to take measures to prevent evaporation of the polar solvent. For example, when the heat treatment temperature during aging is 60 ° C. or higher, the aging time is preferably within 3 hours.

The aging is not required to use a special device, and can be performed by maintaining the above temperature in a storage container or a transportation container. In this case, it is preferable to adopt measures for preventing volatilization due to vaporization of the polar solvent, for example, use of a pressurized container or installation of a condenser in the container.

In the present invention, the viscosity of the cationic resin-modified silica dispersion obtained by the above method is generally 5
0 to 500 mPa · s.

As will be understood from the above description, by preparing a coating liquid using a cationic resin-modified silica dispersion having the properties specified as the cationic resin-modified silica dispersion of the present invention, It is possible to produce a coating liquid of stable quality with good reproducibility.

[0055]

As will be understood from the above description, the cationic resin-modified silica dispersion of the present invention has extremely high stability, and particularly has good reproducibility when used in an ink jet coating liquid. It is possible to prepare a stable coating liquid.

[0056]

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

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

(Measurement of pH and Viscosity) The pH of the cationic resin-modified silica dispersion was measured at 30 ° C. using a pH meter manufactured by Horiba, Ltd. The viscosity was measured at 30 ° C. using a B-type viscometer manufactured by Tokimec.

(Quantification of Silanol Group) For the determination of silanol group, an active hydrogen determination method based on the following reaction formula using a Grignard reagent (CH3MgI) was employed. CH ₃ MgI + SiOH → SiOMgI + CH ₄ (1) As a procedure, the quantified silica was put into a thin glass sphere and dried at 110 ° C. under reduced pressure (0.1 mmHg) for 4 hours. After sealing the glass bulb, Grignard reagent (solvent:
(Butyl ether) in an Erlenmeyer flask. Next, a Teflon (registered trademark) stirrer is hit against a glass ball and divided, and the amount of methane generated by the reaction between silica and the Grignard reagent is quantified using a gas burette, and the amount of silanol groups is calculated from the amount of methane gas generated. did.
At the same time, the concentration of the silanol groups was converted into the number of silanol groups per 100 square angstroms using the specific surface area of silica determined by the BET method.

(Stability Test of Cationic Resin-Modified Silica Dispersion) 8 mmol of KOH was added to 1 kg of the cationic resin-modified silica dispersion and mixed well. A homogenizer (Ultra Turrax T-25, manufactured by Squid) was used as a disperser, and dispersion treatment was performed at 10,000 rpm for 5 minutes. While maintaining the dispersion at 30 ° C., the viscosity one hour after the addition of KOH was measured.

The rate of increase in the viscosity was calculated from the measured value of the viscosity.

(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 and Comparative Example 1 Using fumed silica having a specific surface area of 300 m ² / g (manufactured by Tokuyama, Leolosil QS-30), the silica was mixed with pure water so that the weight of the silica became 20% by weight, and a propeller was used. Preliminary dispersion treatment was performed by stirring with a mixer. The resulting paste-form silica slurry was treated once with a treatment pressure of 300 kgf / cm ² using a high-pressure homogenizer (manufactured by Nanomizer; Nanomizer, LA-31) to obtain a silica dispersion. Hereinafter, it is referred to as silica dispersion-A.

The physical properties of the silica dispersion-A were a pH of 3.8 and a viscosity of 300 mPa · s. The concentration of silanol groups in the silica used above was measured and found to be 2.6 per 100 Å.

Next, 3 parts by weight of diallyldimethylammonium chloride-acrylamide copolymer as a cationic resin was added to silica dispersion-A containing 100 parts by weight of silica in terms of solid content, and the mixture was stirred with a propeller mixer. And premixing was performed. When both were mixed, gelation occurred, but by vigorous stirring, a slurry having fluidity was obtained.

The premix was passed 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.

When the physical properties of the cationic resin-modified silica dispersion were measured, the pH was 2.9 and the viscosity was 200 mP.
a · s.

The zeta potential of the silica particles in the silica dispersion-A was -44 mV, and the zeta potential of the silica particles in the cationic resin-modified silica dispersion was +28 mV (when all were at pH 4). That is, it was found that the cationic resin-modified silica dispersion of the present invention was cationized by the above treatment.

The above cationic resin-modified silica dispersion is
Aged at room temperature (25 ° C.) for the period shown in Table 1.

Next, the stability of the cationic resin-modified silica dispersion obtained by the aging was examined. Table 1 shows the results.

[0071]

[Table 1]

A coating solution having a known composition was prepared using the cationic resin-modified silica dispersions of Nos. 5 to 6 of Table 1 of the present invention. As a result, a stable coating solution having good reproducibility was obtained. Could be prepared.

Example 2 and Comparative Example 2 The same fumed silica as in Example 1 was used, and the silica was left in an atmosphere at a temperature of 35 ° C. and a relative humidity of 80% for 2 days to perform a humidification treatment. When the silanol group of the silica after the treatment was quantified, it was 4.1 per 100 square angstroms.
Was individual.

Using the silica, a cationic resin-modified silica dispersion was prepared and aged in the same manner as in Example 1 and Comparative Example 1, and its stability was examined. Table 2 shows the results.

[0075]

[Table 2]

A coating liquid having a known composition was prepared using the cationic resin-modified silica dispersions of the present invention of Nos. 4 to 6 in Table 2 above. As a result, a stable coating liquid having good reproducibility was obtained. Could be prepared.

Example 3 and Comparative Example 3 A silica dispersion-A was prepared in the same manner as in Example 1, and the dispersion was stored at room temperature. After two days, a part of the silica dispersion was dried and the density of silanol groups was measured.
There were eight.

Using the above silica dispersion, a cationic resin-modified silica dispersion was prepared and aged in the same manner as in Example 1 and Comparative Example 1, and its stability was examined. Table 3 shows the results
Shown in

[0079]

[Table 3]

A coating liquid having a known composition was prepared using the cationic resin-modified silica dispersions of the present invention of Nos. 3 to 6 in Table 3 above. As a result, a stable coating liquid having good reproducibility was obtained. Could be prepared.

Example 4 and Comparative Example 4 Commercially available sodium silicate and pure water were charged into a reaction tank so that the concentration of sodium silicate was 5%. The temperature of the reaction vessel was set to 40 ° C., and a neutralization reaction (neutralization rate of 50%
), The temperature of the reaction solution was set to 95 ° C. The sulfuric acid described above was added to the reaction solution until the neutralization ratio reached 100%. Filtration and washing operations were repeated on the generated silica to obtain a dehydrated cake (silica content: 15% by weight). The specific surface area of the silica obtained by drying the dehydrated cake was 280 m ² / g.

To 2 kg of the above dehydrated cake, 500 g of pure water was added.
Was added, and the mixture was premixed by stirring with a propeller mixer. The resulting paste-like silica slurry is subjected to a high-pressure homogenizer (manufactured by Nanomizer; Nanomizer, LA
Using -31) at a treatment pressure of 800 kgf / cm ² three times, a ground silica dispersion was obtained. Hereinafter, it is referred to as silica dispersion-B.

The above silica dispersion was used as the silica dispersion.
Using B, the cationic resin-modified silica dispersion was adjusted and aged in the same manner as in Example 1 except that the silica concentration was changed to 12% by weight, and the stability was evaluated. Table 4 shows the results.

In the case of silica produced in an aqueous solution such as wet silica, when the fine pulverization treatment as performed in this embodiment is performed, a new pulverized surface of silica is generated, so that the effect of aging is reduced. It is thought to have appeared.

[0085]

[Table 4]

A coating liquid having a known composition was prepared using the cationic resin-modified silica dispersions of the present invention of Nos. 4 to 6 in Table 4 above. As a result, a stable coating liquid having good reproducibility was obtained. Could be prepared.

Example 5 and Comparative Example 5 A cationic resin-modified silica dispersion was obtained in exactly the same manner as in Example 1 except that a diallyldimethylammonium chloride polymer was used as the cationic resin.

The above cationic resin-modified silica dispersion was
Aged at room temperature (25 ° C.) for the period shown in Table 5.

Next, the stability of the cationic resin-modified silica dispersion obtained by the aging was examined. Table 5 shows the results.

[0090]

[Table 5]

A coating solution having a known composition was prepared using the cationic resin-modified silica dispersion of the present invention No. 4 in Table 5 above, and as a result, a stable coating solution was prepared with good reproducibility. I was able to.

Example 6 A cationic resin modified dispersion of the present invention was obtained in the same manner as in Example 5, except that the aging of the cationic resin modified silica dispersion was performed at the heat treatment temperature and heat treatment time shown in Table 6. .

Next, the stability of the cationic resin-modified silica dispersion obtained by the aging was examined. Table 6 shows the results.

[0094]

[Table 6]

A coating solution having a known composition was prepared using the cationic resin-modified silica dispersions of the present invention of Nos. 1 to 3 in Table 6 above. As a result, a stable coating solution having good reproducibility was obtained. Could be prepared.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 3/14 550 C09K 3/14 550Z B41J 3/04 101Y (72) Inventor Kentaro Fukuda Mikage, Tokuyama City, Yamaguchi Prefecture Town 1-1 Toku Yamauchi

Claims (6)

[Claims] 1. A dispersion in which silica and a cationic resin are dispersed in a polar solvent, wherein silica is contained in an amount of 10 to 30% by weight.
And a rate of increase in viscosity one hour after adding 8 mmol of potassium hydroxide to 1 kg of the dispersion at 30 ° C. is 50% or less. Cationic resin-modified silica dispersion. 2. The method according to claim 1, wherein the silica is dry silica, and the dry silica is dispersed in a polar solvent together with a cationic resin.
A method for producing a cationic resin-modified silica dispersion, comprising aging for 10 days or more at a temperature in the range of 5 to 45 ° C. 3. The silica is fumed silica, which is humidified so that the surface silanol group density of the fumed silica exceeds 4 per 100 square angstroms, and then dispersed in a polar solvent together with a cationic resin. ~ 45
A method for producing a cationic resin-modified silica dispersion, which comprises aging for 7 days or more at a temperature in the range of ° C. 4. The silica is dry silica, and the dry silica is dispersed in a polar solvent to adjust the surface silanol group density to be more than 4 per 100 square angstroms, and then the cationic resin is dispersed. A method for producing a cationic resin-modified silica dispersion, which comprises aging at a temperature in the range of 5 to 45 ° C. for 5 days or more. 5. The silica is a wet silica, a sol-gel method silica or a colloidal silica, and the silica is dispersed together with a cationic resin in a polar solvent.
A method for producing a cationic resin-modified silica dispersion, which comprises aging for 5 days or more at a temperature in the range of 5 ° C. 6. A method for producing a cationic resin-modified silica dispersion, comprising dispersing silica together with a cationic resin in a polar solvent, followed by aging by heating at a temperature of 30 to 70 ° C. .