JP2008272741A - Method of manufacturing composite silica particle film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a particle film without compressing by using a specific material as a functional fine particle. <P>SOLUTION: The method of manufacturing a composite silica particle film formed by holding a liquid in gaps between the particles comprises a step for applying a colloidal silica coating liquid prepared by colloidally dispersing silica in a solvent to form a coating film, a step for forming the silica particle film by removing the solvent from the coating film and a step for supplying the liquid to the gaps between the silica particles forming the silica particle film and holding the liquid in the gaps. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a method for producing a composite silica particle film in which a liquid is held in voids between silica particles.

  Conventionally, a laminate in which a particle film is formed on a support is known. For example, Patent Document 1 discloses a functional film including a compressed layer of functional fine particles obtained by compressing a functional fine particle-containing layer formed by coating on a support. Patent Document 1 also discloses that light scattering on the surface of the particle film can be suppressed by impregnating the functional film with a transparent substance.

JP 2002-36411 A

However, it is necessary to compress the layer after forming the functional fine particle-containing layer. Therefore, the arrangement of the particles in the particle film may be distorted or the particles themselves may be damaged.
The present inventors have found that by using a specific material as the functional fine particles, a particle film can be formed without compression, and the present invention has been achieved.

That is, the present invention is a method for producing a composite silica particle film in which a liquid is held in voids between particles,
A step of applying a colloidal silica coating liquid in which silica is colloidally dispersed in a solvent on a support to form a coating film;
Removing the solvent from the coating film to produce a silica particle film,
It is a manufacturing method of the composite silica particle film | membrane consisting of the process of supplying a liquid to the space | gap between the silica particles which form the said silica particle film, and hold | maintaining the said liquid.

According to the present invention, since it is possible to form a particle film without compression, it is possible to form a silica particle film that maintains the properties of the colloidal silica used as the material and does not disturb the particle arrangement. . By holding a liquid according to the purpose in such a silica particle film, a composite silica particle film that can exhibit an excellent function can be obtained.

The material for the support in the present invention is not particularly limited, and examples thereof include known resins such as thermoplastic resins and thermosetting resins, and glass. The support may be a single-layer substrate composed of a single layer or a multilayer substrate composed of two or more layers. Moreover, a chemical | medical agent, various additives, etc. may be contained.
From the viewpoint of transparency and flexibility, it is a support formed from an olefin resin, chlorine-containing resin, fluorine-containing resin, polyester resin, acrylic resin, styrene resin, cellulose resin, polycarbonate resin, or the like. It is preferable. The support can be removed by any method after producing a silica particle film or a composite silica particle film. The shape, size, and thickness of the support are not particularly limited.

  In the present invention, a colloidal silica coating liquid in which silica is colloidally dispersed in a solvent is used. The solvent is usually water. For the purpose of stabilizing the dispersion of silica, an additive such as a surfactant or an organic electrolyte may be added to the coating solution. When a coating liquid contains surfactant, the content is 0.1 weight part or less normally with respect to 100 weight part of solvents. The surfactant used is not particularly limited, and examples thereof include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant.

Examples of the anionic surfactant include alkali metal salts of carboxylic acid, specifically sodium caprylate, potassium caprylate, sodium decanoate, sodium caproate, sodium myristate, potassium oleate, tetramethyl stearate. Examples include ammonium and sodium stearate. In particular, an alkali metal salt of a carboxylic acid having an alkyl chain having 6 to 10 carbon atoms is preferable.

Examples of the cationic surfactant include cetyltrimethylammonium chloride, dioctadecyldimethylammonium chloride, -N-octadecylpyridinium bromide, cetyltriethylphosphonium bromide, and the like.

Examples of the nonionic surfactant include sorbitan fatty acid ester glycerin fatty acid ester and the like.
Examples of amphoteric surfactants include 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine and lauric acid amidopropyl betaine.

When the coating solution contains an organic electrolyte, the content is usually 0.01 parts by weight or less with respect to 100 parts by weight of the solvent. The organic electrolyte in the present invention refers to an organic compound having an ionizable ionic group that is not a surfactant. Examples thereof include sodium p-toluenesulfonate, sodium benzenesulfonate, potassium butylsulfonate, sodium phenylphosphinate, sodium diethylphosphate, and the like. The organic electrolyte is preferably a benzenesulfonic acid derivative.

  The colloidal silica to be used is preferably spherical from the viewpoint of uniformity and density of the formed layer. Colloidal silica such as so-called chain silica in which spherical silica particles are linked in a chain can also be used. By using colloidal silica, it is possible to produce a particle film in which particles are firmly bonded to each other without being compressed.

  The coating liquid used in the present invention may contain a solid component other than silica. When a coating solution containing a solid component other than silica is used, the formed particle film is a film formed from silica and the solid component. When the coating liquid to be used contains a solid component other than silica, the content is usually 10 parts by weight or less with respect to 100 parts by weight of silica.

The particle diameter (Da) of the colloidal silica used in the present invention is preferably 1-1000 nm, more preferably 50-1000 nm, and even more preferably 70-500 nm. By using colloidal silica having such a particle size, the liquid is easily supplied to the voids between the particles by capillary action. In addition, it is preferable that the particle diameter of 80 weight% or more colloidal silica is the said range among the colloidal silica to be used, and it is more preferable that the particle diameter of 90 weight% or more colloidal silica is the said range.
The particle diameter (Da) of colloidal silica can be determined as a sphere equivalent diameter by a dynamic light scattering method, a Sears method, a BET method, a laser diffraction scattering method, or the like. What is necessary is just to select a measuring method suitably with the magnitude | size of colloidal silica. For example, the BET method or the laser diffraction / scattering method is preferably used for fine particles of several tens of nm or less. The particle diameter can be measured by a dynamic light scattering method using a commercially available particle size distribution measuring apparatus. The Sears method is referred to Analytical Chemistry, vol. 28, p. 1981-1983, 1956, which is an analytical technique applied to the measurement of the average particle size of colloidal silica, and is consumed until the pH = 3 colloidal silica dispersion is brought to pH = 9. In this method, the surface area is determined from the amount of NaOH, and the equivalent sphere diameter is calculated from the determined surface area.

In addition, the material is not particularly limited as long as it is a particle having a property capable of forming a particle film without undergoing a compression step instead of the silica of the present invention, and any of inorganic fine particles and organic fine particles can be used for the particle film. . Examples of the inorganic fine particles include metal fine particles, metal oxide fine particles, metal hydroxide fine particles, metal carbonate fine particles, and metal sulfate fine particles. Examples of the metal element of the metal fine particles include gold, palladium, platinum, and silver. As metal elements in metal oxide fine particles, metal hydroxide fine particles, metal carbonate fine particles, metal sulfate fine particles, silicon, aluminum, zinc, magnesium, calcium, barium, titanium, zirconium, manganese, iron, cerium, nickel, Examples include tin. Examples of the organic fine particles include fine particles of a styrene polymer, an acrylic polymer, a siloxane polymer, an amine polymer, a urethane polymer, and the like. Specific examples include organic particles such as polystyrene, polyacryl, polyamide, polyimide, polyurethane, polycarbonate, and silicon.

The first step of the present invention is a step of applying a colloidal silica coating solution as described above onto a support to form a coating film.
In the present invention, the method for applying the colloidal silica coating solution on the support is not particularly limited. For example, gravure coating, reverse coating, brush roll coating, spray coating, kiss coating, die coating, dipping, bar coating It can apply | coat by well-known methods, such as. The coating amount of the colloidal silica coating solution and the number of coatings are not particularly limited, but from the viewpoint of the uniformity of the coating film thickness, the coating amount in one coating may be 1 to 20 g / m ^2. preferable.

Before applying the colloidal silica coating solution, pretreatment such as corona treatment, ozone treatment, plasma treatment, flame treatment, electron beam treatment, anchor coating treatment, and washing treatment may be performed on the support surface.

The second step of the present invention is a step of producing a silica particle film by removing the solvent from the coating film. The removal of the solvent can be performed, for example, by heating under normal pressure or reduced pressure. The pressure at the time of removing the solvent and the heating temperature can be appropriately selected according to the solvent to be used. For example, when the solvent is water, it can be generally dried at 20 to 80 ° C.

The thickness of the silica particle film formed by the second step is not particularly limited, and can be appropriately set depending on the purpose. Usually, the said silica particle film is 0.3-9 micrometers, Preferably it is 2-6 micrometers.

The third step of the present invention is a step of supplying a liquid to the gaps between the silica particles forming the silica particle film and holding the liquid. Since the silica particle film formed in the second step is formed so that the particles are partially in contact with each other, voids exist between the particles. As in the present invention, first, a particle film is prepared, and then liquid is supplied to the voids of the particle film, whereby the liquid supply rate between the particles can be freely controlled and various functions can be imparted.

The type of liquid to be supplied is not particularly limited, and various liquids can be supplied according to the function desired to be expressed. Examples thereof include various resins and precursors thereof, solvents, ionic liquids, active substances, and the like. .
For example, when a non-volatile organic solvent having a refractive index close to that of silica is used as the liquid, a specific reflection peak caused by the regular arrangement of the particles by supplying the liquid to the voids of the particle film, Flattening can be performed while keeping the reflectance low. In addition, when a volatile drug is used as a liquid, the drug supplied to the gaps between the particles becomes very fine droplets in the gaps between the particles, so that a vapor pressure drop occurs and the volatilization rate of the drug is slowed down. It is possible to produce a drug sustained-release membrane using this function. The composite silica particle film of the present invention is excellent in strength and is excellent in flexibility when a film is used as a support. Therefore, the composite silica particle film can be used for various applications as a flexible film having high strength.

The viscosity of the liquid liquid supplied to the silica particle film is not limited, but is preferably 200 Pa · s or less, more preferably 1.5 Pa · s or less from the viewpoint of easy supply to the particle film. preferable. The viscosity of the liquid supplied to the silica particle film can be measured using a commercially available viscometer.

In the present invention, the method for supplying the liquid to the silica particle film is not particularly limited, and for example, a known amount of liquid such as gravure coating, spray coating, dipping, bar coating, etc. It can also be dropped and supplied to the surface of the particle film using any method such as a dropper. The liquid is not necessarily supplied from the outermost layer of the particle film, and the liquid is supplied from the contact surface between the support and the particle film by allowing the liquid to be contained in the support and bleeding from the support surface. It is also possible to do. The amount of contact and the number of times of contact of the solution are not particularly limited, but the amount supplied in one operation is preferably 1 to 10 g / m ² from the viewpoint of the solution holding power of the particle film. The liquid penetrates the entire particle film due to the capillary force of the particle film.

The supply state of the liquid into the particle film can be arbitrarily set depending on the use of the composite silica particle film. The liquid may be supplied to all the voids of the particles in the particle film, or the minimum amount of liquid necessary for coating each particle surface may be supplied. The liquid may remain on the particle film surface, or the liquid may be removed from the particle film surface by a method such as wiping. When a solution in which a solid component is dissolved in a solvent is used as the liquid, the solvent is removed by a method such as drying after supplying the solution between the particles, and only the solid component is placed between the particles or on the particle surface. It can also be left.

In order to improve the affinity between the silica particles constituting the particle film and the liquid supplied between the particles, the silica particles or the silica particle film may be subjected to a hydrophobic treatment. A known method can be used as the processing method.

In the present invention, composite silica particle membranes suitable for various applications can be produced by appropriately selecting the type and configuration of the support, the type and particle size of silica particles, and the type of liquid. According to the method for producing a composite silica particle film of the present invention, a composite silica particle film having excellent strength can be produced. For example, when a non-volatile solvent with a low refractive index (1.5 or less) is selected as the liquid to be supplied between the particles, it is possible to produce a composite silica particle film with excellent transparency and strength, such as LCD, PDP, CRT It is suitable as a hard coat material for protecting the surface of various displays and screens such as organic EL and inorganic EL.

Evaluation methods of the silica particle film and the composite silica particle film are as follows.
<Pencil hardness evaluation>
Based on JISK5400, the measurement was performed with a load of 500 gf.
<Transparency evaluation>
Based on JIS K7105, it measured using the direct-reading type | mold haze computer (HGM-2DP; C light source; Suga Test Instruments make).
<Internal structure evaluation>
A black vinyl tape was affixed to the surface of the support on which the particle film was not laminated, and the regular reflectance (incident angle 5 °) was measured with an ultraviolet-visible spectrophotometer (UV-3150; manufactured by Shimadzu Corporation).
<Electrical conductivity evaluation>
The surface resistivity of the particle film was measured using a super insulation meter (SM-8220; manufactured by Hioki Electric).
The electrode was SME-8310 (manufactured by Hioki Electric), and the measurement was performed under the conditions of a charging time of 10 seconds and a measuring time of 10 seconds.

[Reference Example 1]
A triacetyl cellulose film (thickness: 80 μm) was used as a support. Colloidal silica (1) (trade name: Snowtex ST-XL; average particle diameter 50 nm by BET specific surface area method; solid content concentration 40 wt%; solvent: water; manufactured by Nissan Chemical Industries, Ltd.) 400 g, colloidal silica (2) ( Product name: Snowtex ST-XS; mean particle diameter 4-6 nm by Sears method; solid content concentration 20% by weight; solvent: water; manufactured by Nissan Chemical Industries, Ltd.) 200 g, liquid medium 1400 g is mixed, The mixture was stirred using a tic stirrer to prepare a colloidal silica coating solution (A). When the total volume of silica (1) and silica (2) in the coating solution (A) is 100%, the proportion of silica (1) is 80% and the proportion of silica (2) is 20%.
This coating liquid (A) was apply | coated 13 times using the gravure roll on the base material. Then, it dried at 60 degreeC, the solvent was removed, the silica particle film was formed on the support body, and the laminated body (1) was obtained.

[Example 1]
2 g of bis (2-ethylhexyl) phthalate (manufactured by Wako Pure Chemical Industries, Ltd.) was dropped onto the laminate (1) obtained in the above reference example with a dropper, and the liquid remaining on the surface was removed with Kim Towel (trade name; Crecia) 100) was reciprocated and wiped, and the reflectance was measured. It was confirmed that the reflection peak due to the regular arrangement of particles inside the particle film near 250, 360, and 700 nm, which was observed in the reflectance measurement result of the laminate (1) before the liquid supply, disappeared. In addition, the hardness of the particle film was the same as before the liquid supply, and the transparency was improved.

[Reference Example 2]
A triacetyl cellulose film (thickness: 80 μm) was used as a support. Colloidal silica (3) (trade name: Snowtex ST-ZL; average particle diameter 70 nm by BET specific surface area method; solid content concentration 40 wt%; solvent: water; manufactured by Nissan Chemical Industries, Ltd.) 400 g, colloidal silica (2) ( Product name: Snowtex ST-XS; mean particle diameter 4-6 nm by Sears method; solid content concentration 20% by weight; solvent: water; manufactured by Nissan Chemical Industries, Ltd.) 200 g, liquid medium 1400 g is mixed, The mixture was stirred using a tic stirrer to prepare a colloidal silica coating solution (B). When the total volume of silica (3) and silica (2) in the coating solution (B) is 100%, the proportion of silica (3) is 80% and the proportion of silica (2) is 20%.
This coating liquid (B) was apply | coated 10 times using the gravure roll on the base material. Then, it dried at 60 degreeC, the solvent was removed, the silica particle film | membrane was formed on the support body, and the laminated body (2) was obtained. The surface resistivity of the particle film of the laminate (2) was as shown in Table 2.

[Reference Example 3]
2.5 g of 1-ethyl-2-methylimidazolium tetrafluoroborate (manufactured by Merck & Co., Inc.) and 2.5 g of water are mixed, stirred using a magnetic stirrer, and 1-ethyl-2-methylimidazolium tetrafluoro An aqueous borate solution was prepared. 2 g of the aqueous solution was applied onto a triacetyl cellulose film (thickness: 80 μm) using a bar coater. Then, it dried at 23 degreeC for 24 hours, and measured the surface resistivity. The surface resistivity was as shown in Table 2.

[Example 2]
2.5 g of 1-ethyl-2-methylimidazolium tetrafluoroborate (manufactured by Merck & Co., Inc.) and 2.5 g of water are mixed, stirred using a magnetic stirrer, and 1-ethyl-2-methylimidazolium tetrafluoro An aqueous borate solution was prepared. 2 g of the aqueous solution was applied onto the laminate (2) obtained in Reference Example 2 using a bar coater. The coating amount of 1-ethyl-2-methylimidazolium tetrafluoroborate is 0.2 g with respect to 1 g of silica particles. Then, it dried at 23 degreeC for 24 hours, and measured the surface resistivity. The surface resistivity was as shown in Table 2. A conductive functional liquid was retained between the particle films, and functional particle films having higher conductivity than those of Reference Examples 2 and 3 were obtained.

[Reference Example 4]
1-ethyl-2-methylimidazolium tetrafluoroborate was mixed with the colloidal silica coating solution (B), and the mixture was stirred using a magnetic stirrer to prepare a colloidal silica coating solution (C). The addition amount of 1-ethyl-2-methylimidazolium tetrafluoroborate is 0.3 g with respect to 1 g of silica particles. When the coating solution (C) was applied to a triacetyl cellulose film (thickness: 80 μm) using a gravure roll, the solid content was agglomerated on the support, and a particle film could not be formed.

Reflectivity of silica particle film (Reference Example 1) and composite silica particle film (Example)

Claims (3)

A method for producing a composite silica particle film in which a liquid is held in voids between particles,
A step of applying a colloidal silica coating liquid in which silica is colloidally dispersed in a solvent on a support to form a coating film;
Removing the solvent from the coating film to produce a silica particle film,
A method for producing a composite silica particle film, comprising a step of supplying a liquid to a gap between silica particles forming the silica particle film and holding the liquid. The method for producing a composite particle film according to claim 1, wherein the colloidal silica has a particle diameter (Da) of 1 to 1000 nm. The method for producing a composite particle film according to claim 1, wherein the liquid has a viscosity of 200 Pa · s or less.

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