JP4540432B2 - Cationic resin-modified silica dispersion - Google Patents

Description

  The present invention includes various coating agents, semiconductor wafers, and the like for imparting gas barrier properties, corrosion resistance, hydrophilicity, glossiness, liquid absorption, insulation, etc., to recording paper for ink jet, film, resin, glass, metal, etc. The present invention relates to a novel wet silica dispersion useful for the preparation of IC abrasives, emulsion stabilizers and the like.

  An ink jet recording paper has a coating layer that is an ink absorbing layer for ink absorption formed on one or both sides of a support such as paper, and a material for forming the coating layer (hereinafter, referred to as an ink absorbing layer). Wet silica, dry silica, and the like are also used as the coating layer forming material (see, for example, Patent Documents 1, 2, and 3).

  In general, an anionic compound is often used as an ink for ink jet, and the above coating layer is more cationic, and the image density and the ink density when the ink is printed on the ink jet recording paper are better. It is advantageous for improving the water resistance. However, silica used as a coating layer forming material has an anionic property, and there is a concern that image density and water resistance during printing may be reduced. As an improvement measure therefor, a coating layer for applying a coating solution containing a cationic resin containing a cationic group such as silica and a quaternary ammonium base has been proposed (see, for example, Patent Documents 4 and 5).

  However, in recent years, with the spread of personal computers and digital cameras to general households, there has been a demand for ink jet recording paper that can obtain image quality equivalent to photographs. In addition to the water resistance and ink absorbency described above, glossiness is also improved. There is an increasing demand for coating liquids that can provide excellent coating layers.

  On the other hand, among silica used as a coating layer forming material, wet silica obtained by precipitation by reaction of sodium silicate and mineral acid has internal pores in primary particles, Compared to dry silica that does not have internal pores, it has an advantage as a coating layer forming material having high liquid absorbency.

  However, since wet silica particles have strong cohesiveness between primary particles, they tend to form large agglomerated particles in the coating liquid and tend to increase the average particle size. Therefore, the coating layer which applied the coating liquid containing wet silica has the problem that glossiness is low.

  As a measure to solve the above problem, after mixing a silica slurry in which wet silica is dispersed in a polar solvent and a cationic resin, and cationizing the silica surface, the aggregated particles of silica particles in the dispersion are mixed with a high-pressure homogenizer or wet media type There has been proposed a method of producing a cationic resin-modified silica dispersion having a small average particle diameter by mechanically atomizing to a submicron order using a pulverizer (see, for example, Patent Documents 6, 7, and 8).

  On the other hand, in recent years, it has been desired to supply a high-concentration dispersion liquid by reducing transportation costs, increasing the concentration of the coating liquid, and the like. Further, when the silica concentration is high, particularly 22% by weight or more, there is a problem that the storage stability is remarkably lowered.

  In addition, the high-concentration silica dispersion is not sufficient in terms of transparency, and the transparency decreases as the concentration approaches. As a result, the transparency of the coating layer formed using such a silica dispersion is also lowered. If the transparency of this coating layer is lowered, the clarity of the ink density printed on the sheet will be reduced, and it will not be possible to produce color depth in the resulting image, realizing image quality equivalent to that of photographs. It becomes difficult.

JP-A-55-51583 JP 56-144853 A JP 60-204390 A JP-A 61-43593 Japanese Patent Laid-Open No. 62-268682 JP-A-10-181190 JP 2004-50811 A JP 2004-174810 A

  Accordingly, an object of the present invention is a cationic resin-modified silica dispersion in which wet silica is dispersed at a high concentration of 22% by weight or more in a polar solvent, which has high transparency and excellent storage stability. The object is to provide a cationic resin-modified silica dispersion.

  As a result of intensive studies to solve the above problems, the present inventors have conducted a specific atomization treatment of wet silica having a specific BET specific surface area range in a polar solvent using a specific pulverizer, The inventors have found that a cationic resin-modified silica dispersion that achieves the above-mentioned object can be obtained by mixing with a specific cationic resin and dispersing, and the present invention has been completed.

That is, in the present invention, silica slurry obtained by adding wet silica having a BET specific surface area of 170 to 230 m ² / g to a polar solvent at a concentration of 22% by weight or more is used as a medium with ceramic beads having an average particle diameter of less than 0.2 mmφ. After atomization so that the average particle diameter of the wet silica particles is 1 μm or less by the used wet media type pulverizer, the average molecular weight is less than 50,000, and the colloid equivalent value is 4.0 meq / g or more. This is a cationic resin-modified silica dispersion having an average particle size of silica particles of 300 nm or less obtained by dispersing in the presence of a certain cyclic ammonium salt type cationic resin.

  Since the cationic resin-modified silica dispersion of the present invention is highly transparent and excellent in storage stability even at high silica concentrations, various coating agents including coating layer forming materials for inkjet recording paper are used. It can be suitably used as a raw material.

(Wet silica)
The wet silica used in the present invention is also referred to as “white carbon” obtained by precipitating sodium silicate in a solution by neutralizing with a mineral acid. In addition, the wet silica precipitated by the neutralization reaction is not dried after filtration or washing, and it is used in a wet silica cake state, and the cohesive force of silica particles is smaller than when dry powder is used. Therefore, it has good dispersibility and is preferably used.

  In addition, when wet silica is used in a cake, the wet silica cake increases the water content and decreases the concentration when the specific surface area of the silica is increased, so the silica concentration in the silica dispersion is increased and the dispersibility is also improved. For this purpose, it is preferable to use wet silica cake and wet silica powder (dried product) by mixing them and increasing the silica concentration.

  Of course, in the present invention, wet silica can be used only as a dry powder.

The wet silica used in the present invention has a BET specific surface area of 170 to 230 m ² / g, preferably 180 to 220 m ² / g, and has high transparency and excellent storage stability. Necessary for obtaining a resin-modified silica dispersion.

That is, the wet silica having a BET specific surface area of more than 230 m ² / g is easy to aggregate in a polar solvent because the primary particles are small. In particular, this phenomenon tends to become more prominent as the silica concentration increases. Accordingly, when the high concentration cationic resin-modified silica dispersion liquid of the present invention is produced using wet silica having a BET specific surface area of 230 m ² / g or more, the storage stability is deteriorated, and the dispersion liquid is gradually deteriorated over time. The viscosity increases, and in some cases, the whole dispersion tends to be easily gelled.

In addition, wet silica having a BET specific surface area of less than 170 m ² / g has a large primary particle size, and thus the transparency of the cationic resin-modified silica dispersion using the wet silica tends to decrease.

  The BET specific surface area is a specific surface area measured by applying multi-layer adsorption theory and is considered to correspond to the average primary particle diameter of silica (J. Am. Chem. Soc. 60, P309 (1938)). Further, as described in the powder physical property diagram (powder engineering workshop, edited by Japan Powder Industry Association, P85 (1975)), assuming that the primary particles are spherical, the specific surface area and the primary particles The average diameter has the relationship of the following formula (1). The larger the specific surface area, the smaller the average primary particle diameter.

D = 6 / (S · ρ) (1)
(Where D is the average primary particle size, S is the specific surface area, and ρ is the density of the particles).

(Polar solvent)
The polar solvent used in the present invention is not particularly limited as long as it is a polar solvent in which wet silica and a cationic resin are easily dispersed. As such a polar solvent, water is most preferable. Of course, in addition to water, polar solvents such as alcohols such as methanol, ethanol and isopropyl alcohol, ethers and ketones can be used, and a mixed solvent of water and the above-mentioned polar solvent can also be suitably used.

  In order to improve the storage stability and dispersibility of the silica particles, a small amount of a surfactant such as a silane coupling agent, an antifungal agent or the like may be added within a range not impairing the effects of the present invention.

(Silica dispersion)
In the present invention, a silica slurry is prepared by adding the wet silica to a polar solvent so as to have a concentration of 22% by weight or more, particularly, 24 to 35% by weight. As a result, the resulting cationic resin-modified silica dispersion The silica concentration in the liquid is 22% by weight or more.

Thus, the silica concentration in the coating liquid when used as a coating layer forming material can be increased by setting the silica concentration of the finally obtained cationic resin-modified silica dispersion to 22% by weight or more. Since it can, it has the following effects.
(1) Even if the concentration of other additives added to the coating liquid is low, a certain level of coating liquid concentration can be maintained, so that options for usable additives are widened.
(2) A coating layer having a sufficient thickness can be formed by a single coating in the coating after the coating solution is prepared.
(3) High energy efficiency when drying after coating.
(4) A high silica concentration in the cationic resin-modified silica dispersion is advantageous from the viewpoint of physical distribution costs.

  However, in the conventionally proposed silica dispersions, there was no cationic resin-modified silica dispersion exhibiting stability in a state where wet silica was dispersed at the high concentration. On the other hand, the present invention uses a silica slurry using wet silica having the above specific BET specific surface area, using a wet media type pulverizer using ceramic beads having an average particle diameter of less than 0.2 mmφ as a medium. The stabilization of the cationic resin-modified silica dispersion obtained by making the silica particles finer to 1 μm or less and then mixing with a specific cationic resin was achieved.

  The atomization apparatus that can be used to atomize the average particle diameter of wet silica particles in a polar solvent to 1 μm or less employs the principle of atomization and pulverization by the impact action between the pulverization media and the object to be pulverized. Wet media type pulverizer is used.

In general, a wet media type pulverizer is a pulverizer that uses beads having an average particle diameter of about 0.01 to 3 mmφ as a medium, but according to the knowledge of the present inventors, the beads used have a large average particle diameter. As a result, the contamination of the impurities due to the wear of the beads tends to increase. And it became clear that mixing of the impurity by bead origin becomes the cause which reduces the transparency of the silica dispersion liquid after atomization processing.
Therefore, the media of the wet media type pulverizer used in the present invention must be beads having a diameter of less than 0.2 mmφ. Further, the beads used in the wet media type pulverizer need to be made of ceramic from the viewpoint of hardness. Especially, it is preferable that it is a product made from a zirconia.
Specific examples of wet media type pulverizers include: Inoue Seisakusho brand name; Mighty Mill, Imex brand name; Visco Mill, Ashizawa brand name; Agitator mill, Kotobuki Giken brand name; Trade names manufactured by Super Apex Mill, Ultra Apex Mill, and Willy et Bakkofen;

  In addition, the wetted part of the wet media type pulverizer is preferably made of a material having high wear resistance with respect to silica, such as ceramic mainly composed of zirconia or alumina, or polyurethane or polyethylene resin.

  In addition to wet media type pulverizers, there are ultrasonic dispersers and high-pressure homogenizers as an apparatus for atomizing wet silica, which are not practical and are used in the preparation of the silica dispersion of the present invention. I can't.

  In the preparation of the silica dispersion, in order to effectively prevent thickening and gelation in the middle of obtaining a cationic resin-modified silica dispersion having a silica concentration of 22% by weight or more, a wet media type pulverizer is used. Prior to atomization, it is preferable to adjust the pH of the silica slurry to be less than 5.

  As a method for adjusting the pH of the silica slurry to less than 5, after adjusting the pH by previously adding a mineral acid such as sulfuric acid to a polar solvent, wet silica is dispersed in the polar solvent, or wet silica and sulfuric acid. A method of preparing a silica slurry by dispersing wet silica in a polar solvent while simultaneously adjusting pH by adding a mineral acid such as the above.

  The disperser used to adjust the pH of the silica slurry to less than 5 is not particularly limited, but is a general stirrer having propeller blades, turbine blades, paddle blades, etc., a high-speed rotating centrifugal radiation stirrer such as a disper mixer, a homogenizer Dispersers such as high speed rotary shear type stirrers such as homomixers and ultra mixers, colloid mills, planetary mixers and suction type dispersers, and a combination of the above high speed rotary shear type stirrers and propeller blades and paddle blades Examples thereof include a composite disperser in which a type disperser, a planetary mixer and a high-speed rotary centrifugal radiation type stirrer or a high-speed shear type stirrer are combined.

  The average particle diameter of the silica particles refers to an average particle diameter measured immediately after preparation of a silica dispersion (within 10 minutes after preparation) by subjecting the silica slurry to a atomization treatment with a wet media type pulverizer.

  Further, when a time of 10 minutes or more has elapsed after the atomization treatment, the silica particles in the silica dispersion liquid reaggregate, and the average particle diameter of the silica particles may be apparently 1 μm or more. Even when agglomerated, it can be used in the present invention.

In the present invention, the average particle diameter refers to the average particle diameter of the silica agglomerated particles in the silica dispersion, and is the volume-based arithmetic average diameter D ₅₀ as measured with a light scattering diffraction type particle size distribution meter. That is.

(Cationic resin)
In the present invention, the cationic resin used is a cyclic ammonium salt type cationic resin having an average molecular weight of less than 50,000 and a colloid equivalent value of 4.0 meq / g or more. Necessary for obtaining an excellent cationic resin-modified silica dispersion.

  The cyclic ammonium salt-type cationic resin is a cyclic ammonium salt-type cationic resin obtained by polymerizing a diallylammonium salt and a derivative thereof. Specific examples include the following structural formula (1) or structural formula ( 2) The diallylammonium salt having a repeating unit represented by 2) and a polymer thereof, 10 to 90 mol% of a repeating unit represented by structural formula (1) or structural formula (2), and a diallylammonium salt and a derivative thereof can be copolymerized. Mention may be made of copolymers having 90 to 10 mol% of repeating units based on monomers.

構造式（１）、構造式（２）において、Ｒ^１及びＲ^２は、水素原子又はメチル基、エチル基を表す。ジアリルアンモニウム塩及びその誘導体と共重合可能なモノマーに基づく繰り返し単位としては、好ましくは、アクリルアミド、モノアリルアミン塩酸塩に基づく繰り返し単位が挙げられる。

In Structural Formula (1) and Structural Formula (2), R ¹ and R ² represent a hydrogen atom, a methyl group, or an ethyl group. As the repeating unit based on a monomer copolymerizable with a diallylammonium salt and a derivative thereof, a repeating unit based on acrylamide or monoallylamine hydrochloride is preferable.

  In the present invention, the average molecular weight of the cyclic ammonium salt type cationic resin needs to be less than 50,000. When the average molecular weight of the cationic resin is 50,000 or more, as described above, when a cationic resin-modified silica dispersion having a silica concentration of 22% by weight or more is produced, the storage stability tends to deteriorate. The average molecular weight of the cyclic ammonium salt type cationic resin is preferably 1,000 to 45,000, more preferably 1,000 to 25,000.

  In addition, in this invention, an average molecular weight is the polyethylene conversion value calculated | required from the gel permeation chromatography.

  In the present invention, the colloidal equivalent value of the cyclic ammonium salt type cationic resin is 4.0 meq / g or more. When the colloid equivalent value of the cationic resin is less than 4.0 meq / g, as described above, when a cationic resin-modified silica dispersion having a silica concentration of 22% by weight or more is produced, the storage stability is deteriorated. The colloidal equivalent value of the cyclic ammonium salt type cationic resin is preferably 4.5 meq / g or more, more preferably 5.0 meq / g or more.

  In the present invention, the colloid equivalent value is a cationic colloid equivalent value determined by a colloid titration method.

  In the present invention, a particularly preferable cationic resin has an average molecular weight of 1,000 to 25,000 and a colloidal equivalent value of 5.0 meq / g or more. 2) a polymer of a diallylammonium salt having a repeating unit represented by formula (2) and a derivative thereof, copolymerized with 10 to 90 mol% of a repeating unit represented by structural formula (1) or structural formula (2), and a diallylammonium salt or derivative thereof. One type of cationic resin selected from a copolymer having 90 to 10 mol% of repeating units based on possible monomers, or a cationic resin obtained by mixing two or more types.

(Cationic resin-modified silica dispersion)
The silica dispersion obtained by the above method is then subjected to a dispersion treatment in the presence of a cationic resin to obtain a cationic resin-modified silica dispersion.

  The method of mixing the silica dispersion and the cationic resin is not particularly limited, but a method of adding and mixing the silica dispersion to the aqueous solution of the cationic resin is preferable. Further, the means for mixing and dispersing the silica dispersion and the cationic resin is not particularly limited, and a known disperser, for example, a high-speed rotating centrifugal radiation stirrer, a high-speed rotating shear stirrer, a colloid mill, or a planetary mixer. General dispersion machines such as suction type dispersion machines, special dispersion machines such as high-pressure homogenizers, and composite dispersion machines that combine these dispersion machines can also be used. The resulting cationic resin-modified silica dispersion In order to make the cationic resin uniformly adhere to the surface of the silica particles and to make a more stable dispersion, the high-pressure homogenizer that can uniformly attach the cationic resin to the silica surface mechanochemically It is recommended to use

  Specific examples of such high-pressure homogenizers include nanomizer product names; nanomizer, microfluidics product names; microfluidizers, and Sugino Machine optimizers.

  Specifically, a preferable dispersion method is a method in which the silica slurry and the cationic resin are mixed with the above-mentioned general disperser and then highly dispersed with a high-pressure homogenizer. In this case, the processing pressure of the high-pressure homogenizer is 30 MPa or higher, particularly 50 to 250 MPa, and the opposite collision is performed, or the differential pressure between the inlet side and the outlet side of the orifice is 30 MPa or higher, particularly 50 to 250 MPa. It is preferable.

  In general, there is a case where silica particles reaggregate in a mixture of a silica dispersion having an average particle size of 1 μm or less and a cationic resin, and the viscosity suddenly increases when the dispersion is further strongly dispersed. After that, the viscosity tends to decrease. A high-pressure homogenizer is very suitable for such a liquid whose viscosity changes abruptly.

  In the present invention, the amount of the cationic resin used in the cationic resin-modified silica dispersion is such that the cationic resin-modified silica dispersion can be stably produced without thickening or gelling during the production, and the obtained cation 2-20 parts by weight, particularly 2-15 parts by weight with respect to 100 parts by weight of silica in order to lower the viscosity of the functional resin-modified silica dispersion and improve the storage stability of the dispersion. Is preferred.

  Since the viscosity and storage stability of the cationic resin-modified silica dispersion with respect to the addition amount of the cationic resin differ depending on the type of the cationic resin to be added, the viscosity of the dispersion becomes low by experiments and the storage stability is determined in advance. It is preferable to select an optimum addition amount that provides the best performance from the range of the addition amount.

(Other conditions)
In the present invention, in order to produce more stably without causing thickening and gelation during the production of the cationic resin-modified silica dispersion, in each case, a temperature range of 45 ° C. or lower, particularly 20 to 40 ° C. It is preferable to control.

  The method for controlling the temperature range is not particularly limited, and a known cooling means that does not affect the composition of the liquid is employed without any particular limitation. For example, by appropriately selecting cooling means such as installation of a jacket type cooler outside each dispersion tank, installation of cooling piping inside each dispersion tank, installation of a heat exchanger at each equipment inlet or outlet piping section, etc. Apply.

(Characteristics of cationic resin-modified silica dispersion)
The cationic resin-modified silica dispersion of the present invention was prepared by preparing a silica dispersion by the previous method, and further dispersing in the presence of the cationic resin, so that the average particle size of the dispersed wet silica was 300 nm. The following can be achieved: On the other hand, when the average particle diameter of silica exceeds 300 nm, particularly when it is used as a coating layer forming material for ink jet recording paper, the surface of the coating layer cannot be smooth and the gloss is insufficient. Occurs. That is, when a cationic resin-modified silica dispersion having an average particle diameter of silica of 300 nm or less is used as a coating layer forming material for ink jet recording paper, smoothness is obtained on the coating layer surface and gloss is increased.

  The average particle diameter of the silica of the cationic resin-modified silica dispersion is preferably 60 nm to 250 nm, more preferably 60 nm to 200 nm, in order to achieve both glossiness and ink absorbability at a high level. It is preferable to select the conditions for dispersion.

In the present invention, the average particle diameter refers to the average particle diameter of the silica agglomerated particles in the cationic resin-modified silica dispersion, and is a volume-based arithmetic average when measured with a light scattering diffraction type particle size distribution meter. is that the diameter _{D 50.}

  Thus, a system in which the wet silica in the cationic resin-modified silica dispersion is stably present in a finely dispersed state with an average particle diameter of 300 nm or less is achieved for the first time by the series of methods disclosed by the present invention. Is.

  As described above, the cationic resin-modified silica dispersion obtained by the present invention is a highly transparent, unprecedented high transparency in a silica dispersion using wet silica, although the silica concentration is 22% by weight or more. And storage stability.

  The transmittance of the cationic resin-modified silica dispersion of the present invention can achieve 20% or more, the transparency of the coating liquid produced using the dispersion is high, and the transparency of the coating layer is improved. can do. When the transparency of the coating layer is increased, the density of the ink applied to the coating layer becomes clear, and the color of the obtained image is deepened so that an image quality similar to that of a photograph can be realized.

  In the present invention, the transmittance is the absorbance at a measurement wavelength of 700 nm of the liquid diluted to a silica concentration of 1.5% by weight using the same polar solvent as that of the cationic resin-modified silica dispersion. τ) is a value obtained by measuring the transmittance (T) by a spectrophotometer and calculating the following formula (2).

T (%) = 10 ^(2-τ) (2)
Further, the cationic resin-modified silica dispersion of the present invention exhibits high storage stability, but the storage stability index can achieve less than 1.5. Due to this high storage stability, the cationic resin-modified silica dispersion of the present invention has the following merits.
(1) The handling property at the time of discharging the dispersion from a container, tank or the like filled with the cationic resin-modified silica dispersion is improved.
(2) It is possible to stably set conditions such as piping transportation of the cationic resin-modified silica dispersion.
(3) It becomes easy to change the physical properties of the coating liquid and to set the coating conditions by increasing the viscosity of the coating liquid using the cationic resin-modified silica dispersion.

  In the present invention, the above-mentioned storage stability index is determined by the viscosity (A (mPa · s) of the production of the cationic resin-modified silica dispersion immediately after production) and the dispersion which has been stored in an indoor environment at 25 ° C. for 10 days. The viscosity (B (mPa · s)) was measured, and the storage stability index (Δμ) was determined by the following mathematical formula (3).

Δμ = B / A (3)
It can be said that as Δμ calculated by the mathematical formula (3) is closer to 1, the viscosity change of the cationic resin-modified silica dispersion is less and the storage stability is higher.

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

The physical properties of the cationic resin-modified silica dispersion were measured by the following method.
(1) Viscosity measurement After collecting 300 g of a cationic resin-modified silica dispersion in a 500 ml container and placing it in a thermostatic bath at 30 ° C. for 10 minutes, a cation was obtained at 60 rpm using a B-type viscometer (manufactured by Tokimec, BL). The viscosity of the functional resin-modified silica dispersion was measured.
(2) pH measurement After collecting 300 g of silica slurry or cationic resin-modified silica dispersion in a 500 ml container and placing it in a thermostatic bath at 30 ° C. for 10 minutes, using a pH meter (Horiba, F-22), silica The pH of the slurry and the cationic resin-modified silica dispersion was measured.
(3) Measurement of average particle size After the dispersion is diluted with ion-exchanged water so that the silica concentration of the silica dispersion or the cationic resin-modified silica dispersion is 10% by weight, the particle size distribution of light scattering diffraction type measuring device (Coulter, Coulter LS-230) was used to measure the volume-based arithmetic mean diameter D _50, employing this value as the average particle size.

  However, the average particle size of the silica dispersion was measured immediately after the preparation of the silica dispersion (within 10 minutes after the preparation).

In the measurement, the refractive index of water (dispersion medium) 1.332 and the refractive index of silica 1.458 were input as parameters.
(4) Measurement of transmittance After the dispersion was diluted with ion-exchanged water so that the silica concentration of the cationic resin-modified silica dispersion was 1.5% by weight, the absorbance (τ) of this diluted solution was measured. It measured using the photometer (the JASCO make, Ubest-35 type | mold), and the transmittance | permeability (T) was computed by Formula (2) mentioned above. In this measurement, the optical path length was 10 mm, and the measurement wavelength was 700 nm.

Example 1
Wet silica powder having a BET specific surface area of 205 m ² / g was dispersed in ion-exchanged water added with 2N sulfuric acid as a pH adjuster to obtain a silica slurry having a silica concentration of 25% by weight. This silica slurry was subjected to a bead diameter of 0.1 mmφ, a bead filling rate of 85%, a rotor peripheral speed of 9.2 m / sec, and a liquid temperature of 30 using a wet media type pulverizer (manufactured by Kotobuki Giken, Super Apex Mill SAM-1) A silica dispersion was obtained by atomization under the condition of ° C. As the silica dispersion and the cationic resin, an aqueous diallyldimethylammonium chloride-acrylamide copolymer aqueous solution having an average molecular weight of 10,000 and a colloid equivalent value of 6.0 meq / g is 4 parts by weight of the cationic resin with respect to 100 parts by weight of silica. The mixture was dispersed and dispersed to obtain a premixed solution. A cationic resin-modified silica dispersion was obtained by subjecting this premixed solution to a strong dispersion treatment using a high-pressure homogenizer (manufactured by Nanomizer, Nanomizer LA-31) at a treatment pressure of 80 MPa and a liquid temperature of 30 ° C.

Example 2
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 1 except that wet silica powder having a specific surface area of 190 m ² / g was used as wet silica powder.

Example 3
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 1 except that wet silica powder having a specific surface area of 215 m ² / g was used as wet silica powder.

Example 4
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 1 except that an aqueous diallyldimethylammonium chloride polymer solution having an average molecular weight of 9,000 and a colloid equivalent value of 6.0 meq / g was used as the cationic resin.

Example 5
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 1 except that an aqueous diallylmethylamine hydrochloride polymer solution having an average molecular weight of 20,000 and a colloid equivalent value of 7.1 meq / g was used as the cationic resin.

Example 6
A cationic resin-modified silica dispersion is obtained in the same manner as in Example 1 except that an aqueous diallyldimethylammonium chloride-acrylamide copolymer aqueous solution having an average molecular weight of 20,000 and a colloid equivalent value of 5.9 meq / g is used as the cationic resin. It was.

Example 7
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 1 except that an aqueous diallyldimethylammonium chloride polymer solution having an average molecular weight of 20,000 and a colloid equivalent value of 6.0 meq / g was used as the cationic resin.

Example 8
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 1 except that an aqueous diallyldimethylammonium chloride polymer solution having an average molecular weight of 40,000 and a colloid equivalent value of 6.4 meq / g was used as the cationic resin.

Example 9
A wet silica cake containing a wet silica powder having a BET specific surface area of 205 m ² / g and a moisture of 84% prior to the drying process of the wet silica powder was dispersed in ion-exchanged water to which 2N sulfuric acid was added as a pH adjuster, and a silica concentration of 25 A weight percent silica slurry was obtained. In addition, the mixing ratio of the wet silica powder and the wet silica cake was 1: 1 by weight ratio in terms of silica. A cationic resin-modified silica dispersion was obtained in the same manner as in Example 1 except that this silica slurry was used.

Comparative Example 1
As wet silica powder, a wet silica powder having a BET specific surface area of 280 m ² / g was used, and the cation was changed in the same manner as in Example 1 except that the mixing amount of the cationic resin was 10 parts by weight with respect to 100 parts by weight of silica. Resin-modified silica dispersion was obtained.

Comparative Example 2
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 1 except that wet silica powder having a BET specific surface area of 130 m ² / g was used as wet silica powder.

Comparative Example 3
A cationic resin-modified silica dispersion was prepared in the same manner as in Example 1 except that a diallyldimethylammonium chloride-acrylamide copolymer aqueous solution having an average molecular weight of 52,000 and a colloid equivalent value of 5.8 meq / g was used as the cationic resin. Obtained.

Comparative Example 4
Cationic resin-modified silica dispersion as in Example 1 except that an aqueous diallyldimethylammonium chloride-maleic acid copolymer aqueous solution having an average molecular weight of 10,000 and a colloid equivalent value of 2.8 meq / g is used as the cationic resin. Got.

Comparative Example 5
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 1 except that an aqueous polyallylamine hydrochloride polymer solution having an average molecular weight of 13,000 and a colloid equivalent value of 14.8 meq / g was used as the cationic resin.

Comparative Example 6
The same procedure as in Example 1 was conducted except that an aqueous solution of methyl methacrylate-ethyl methacrylate-ethyl trimethylammonium chloride copolymer having an average molecular weight of 16,000 and a colloid equivalent value of 2.9 meq / g was used as the cationic resin. A cationic resin-modified silica dispersion was obtained.

Comparative Example 7
A cationic resin-modified silica dispersion was obtained in the same manner as in Example 1 except that the bead diameter was 0.3 mmφ and the bead filling rate was 65% under the conditions for atomization of silica slurry using a wet media type disperser.

Comparative Example 8
A cation-modified silica dispersion was obtained in the same manner as in Example 1 except that the preparation of the silica dispersion by the atomization treatment of the silica slurry was performed using a high-pressure homogenizer under the conditions of a processing pressure of 80 MPa and a liquid temperature of 30 ° C.

  Table 1 shows the properties of wet silica used in the above Examples and Comparative Examples, and silica dispersions obtained by atomization treatment, and Table 2 shows the cationic resins used in Examples and Comparative Examples. Table 3 shows the physical properties of the cationic resin-modified silica dispersions obtained in Examples and Comparative Examples.

実施例１〜９で得られたカチオン性樹脂変性シリカ分散液は、いずれも平均粒子径が３００ｎｍ以下であり、シリカ濃度も２２重量％以上でありながら、粘度的にも良好な保存安定性を有しており、透明性も高いことがわかる。

The cationic resin-modified silica dispersions obtained in Examples 1 to 9 all have an average particle size of 300 nm or less, a silica concentration of 22% by weight or more, and a good storage stability in terms of viscosity. It has a high transparency.

  On the other hand, the cationic resin-modified silica dispersions obtained in Comparative Examples 1 and 3 to 6 had poor storage stability and some gelled. Further, the cationic resin-modified silica dispersions obtained in Comparative Examples 2 and 7, and 8 have poor performance as cationic resin-modified silica dispersions because of low transparency or large average particle diameter. I know that there is.

The cationic resin-modified silica dispersion of the present invention imparts gas barrier properties, corrosion resistance, hydrophilicity, glossiness, liquid absorption, insulating properties, etc. to recording paper for inkjet, films, resins, glass, metals, etc. It can be used as a material such as various coating agents, semiconductor wafers, IC abrasives, and emulsion stabilizers.

Claims (4)

Wet media type pulverization using a ceramic slurry with an average particle diameter of less than 0.2 mmφ as a medium for a silica slurry with a BET specific surface area of 170-230 m ² / g added to a polar solvent at a concentration of 22 wt% or more A cyclic ammonium salt type having an average molecular weight of less than 50,000 and a colloid equivalent value of 4.0 meq / g or more after atomization so that the wet silica particles have an average particle size of 1 μm or less. A cationic resin-modified silica dispersion having an average particle size of silica particles of 300 nm or less, obtained by performing a dispersion treatment in the presence of a cationic resin.   The cationic resin-modified silica dispersion according to claim 1, wherein the dispersion treatment is performed by using a high-pressure homogenizer.   The silica slurry is obtained by previously adjusting the pH of a polar solvent so that the pH is less than 5, and then dispersing wet silica in the polar solvent. The cationic resin-modified silica dispersion according to Item. The cationic resin-modified silica dispersion according to any one of claims 1 to 3, wherein the addition of wet silica to the polar solvent is performed by adding wet silica powder after adding wet silica cake.