KR20170111920A - Microcapsule Comprising Nanoparticle and Manufacturing Method Thereof - Google Patents

Abstract

The present invention relates to nanoparticles comprising a double coating layer and to microcapsules comprising a solvent, wherein the nanoparticles comprising the double coating layer comprise nanoparticles; A primary coating layer comprising a silane containing a fluorine group coated on the surface of the nanoparticles; And a secondary coating layer composed of a material containing a hydrophobic functional group coated on the surface of the primary coating layer.
In addition, the microcapsule may be prepared by: preparing a dispersion medium in which nanoparticles including a double coating layer and a solvent are dispersed; And microencapsulating the dispersion medium.

Description

TECHNICAL FIELD The present invention relates to a microcapsule containing nanoparticles and a method of manufacturing the same.

The present invention relates to a microcapsule containing nanoparticles and a method for producing the same, and more particularly, to a microcapsule containing nanoparticles having improved dispersibility by including a double coating layer and a method for producing the same.

Recently, displays with low power consumption and high flexibility have attracted much attention. Various studies have been conducted to coat or support a flexible substrate such as a film to have high flexibility. Electrophoretic reflection type displays are typically known.

Electrophoretic reflective displays use a method that minimizes leakage current by dispersing nanoparticles in a nonpolar medium for low power consumption.

In general, in order to enhance the electrophoresis and dispersibility of nanoparticles in a nonpolar medium, methods of coating the surfaces of the inorganic nanoparticles themselves have been variously studied. Typically, they are coated by direct polymerization using organic monomers, There has been known a method of surface-coating using Examples thereof include U.S. Patent Publication No. 2012-0268806, Korean Registered Patent No. 10-1090039, and U.S. Patent No. 10-0533146.

In this case, when a surface coating is performed using an inorganic silane material, a silane material containing various functional groups is used in order to impart electrophoretic properties to the non-polar medium.

At this time, if the O / W (oil / water) microencapsulation process is performed after dispersing the electrophoretic nanoparticles coated with the silane material containing the functional group in the nonpolar medium, contact with water due to the hydrophilic property of the surface- Over time, the nanoparticles aggregate in the ink. In addition, when aggregation occurs due to other factors of the nanoparticles in the ink state, the color of the opposite electrode is shaded due to agglomeration of the particles during electrophoresis in the film for final reflection type display, resulting in a problem of poor color clarity.

As a method for overcoming this problem, a method of coating the surface of a white nanoparticle with a silane material having a functional group and then performing a coating with a silane material having only a hydrocarbon group capable of increasing the hydrophobic property of the particle surface .

When the double coated nanoparticles prepared by the above process are stably dispersed in the nonpolar medium to prepare microcapsules and then the film is produced and the electric field is applied, the color sharpness of the display It is expected to increase.

US Patent Publication No. 2012-0268806 Korean Patent Publication No. 10-1090039 Korean Patent Publication No. 10-0533146

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and it is an object of the present invention to provide a nanoparticle having a double coating layer by double coating the surface of nanoparticles exhibiting electrophoretic characteristics, It is an object of the present invention to provide nanoparticles for reducing particle aggregation in a process.

It is another object of the present invention to increase the color sharpness when applied to an electrophoretic display film by applying the nanoparticles as described above to ink and microcapsules.

In order to accomplish the above object, the present invention provides a nanoparticle comprising a double coating layer comprising nanoparticles; A primary coating layer comprising a silane containing a fluorine group coated on the surface of the nanoparticles; And a secondary coating layer composed of a material containing a hydrophobic functional group coated on the surface of the primary coating layer.

At this time, the material including the hydrophobic functional group may be an organic material or an inorganic material including a hydrocarbon group.

In addition, the nanoparticles comprising the double coating layer of the present invention are characterized in that the difference between D90 and D50 in the particle size distribution by the dynamic light scattering method of the nanoparticles of the double coating layer is 200 nm or less.

Further, in the spectrum by infrared spectroscopy, the intensity of the absorption band at 2920 to 2930 cm ^-1 and 2850 to 2860 cm ^-1 for the nanoparticles containing the double coating layer is higher than that of the nano particles containing the double coating layer Wherein the intensity of the absorption band at 1060 to 1070 cm < ^-1 > for the nanoparticle including the double coating layer and the nanoparticle is greater than 20 to 100% for the nanoparticle containing the double coating layer, 30% larger.

A method for preparing nanoparticles comprising a double coating layer of the present invention comprises the steps of: 1) coating a surface of a nanoparticle with a silane having a fluorine functional group; Coating the surface of the primary surface-coated particles with a hydrophobic substance.

In the present invention, the ink is characterized by containing nanoparticles, a dye and a solvent containing the double coating layer.

The method of manufacturing the ink may further include: a step of preparing a dispersion medium for dispersing the nanoparticles, the dye and the solvent including the double coating layer; And microencapsulating the dispersion medium.

In the present invention, the microcapsule is characterized by comprising nanoparticles containing the double coating layer and a solvent. In addition, the microcapsule may include a dye.

Also, the microcapsule may include a step of preparing a dispersion medium in which nanoparticles containing the double coating layer and a solvent are dispersed; And microencapsulating the dispersion medium, wherein the dispersion medium may comprise a dye.

The electrophoretic nanoparticles according to the present invention have an effect of reducing particle aggregation in a microcapsule process and increasing the color sharpness of a film for electrophoretic display since the surface of the electrophoretic nanoparticle is coated with a double coating to increase dispersibility in the nonpolar medium.

1 is a schematic diagram of nanoparticles comprising a dual coating layer of the present invention.
Fig. 2 is a graph showing the results of measurement of the surface roughness of the titanium dioxide nanoparticle (a) coated with fluorosilane, the titanium dioxide nanoparticle (b) of the double coating layer secondary coated with the hydrocarbon silane having 8 carbon atoms A titanium dioxide nanoparticle (c), and a double coating layer of a titanium dioxide nanoparticle (d) secondary coated with a hydrocarbon silane having a carbon number of 16, is applied to a glass substrate.
Fig. 3 is a graph showing the results of measurement of the transmittance of the titanium dioxide nanoparticle (a), the titanium dioxide nanoparticle (b) in which the first coating layer of fluorosilane was formed, and the titanium dioxide nanoparticle (c). Fig.
Fig. 4 is a graph showing the results of measurement of the transmittance of titanium dioxide nanoparticles (a) having no coating layer formed, titanium dioxide nanoparticles (b) having formed a primary coating layer of fluorosilane, and titanium dioxide nanoparticles (c) by infrared spectroscopy.
5 is a graph of particle size distribution of the titanium dioxide nanoparticles (a) forming the primary coating layer of fluorosilane and the titanium dioxide nanoparticles (b) of the double coating layer in which the secondary coating layer is formed with the hydrocarbon silane.
Fig. 6 is a graph showing the results obtained by using microcapsules (a) containing titanium dioxide nanoparticles coated with fluorosilane and microcapsules (b) containing titanium dioxide nanoparticles of a double coating layer secondary coated with 12 carbon atoms of hydrocarbon silane Showing the electrophoretic property when an electric field is applied to the film.

Hereinafter, the present invention will be described in more detail with reference to the drawings. The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

To date, nanoparticles used in electrophoretic displays have been coated with primary organic / inorganic compounds. When the polymerization is carried out by using an organic compound, the process is complicated, the kinds of raw materials to be used are large and the process is long, so that it is difficult to control and it is difficult to mass-produce it in a large amount. In the case of coating an inorganic material such as silane, the process is simple, and the raw materials to be used are simple and easy to control. Therefore, the process control and the mass mass production are easier than the above reaction, while the silane having various functional groups In the case of only tea coating, there is a limitation in that the surface characteristics of the particles become unstable when capsules are produced from water by dispersing the particles in the non-polar medium.

Therefore, if the surface of the nanoparticles is double-coated, the ink dispersed in the nonpolar medium is expected to lower the agglomeration of the particles in the encapsulation process, thereby enhancing the color reproducibility of the electrophoretic display.

In the present invention, the nanoparticles including the double coating layer are formed with a double coating layer on the surface of the nanoparticles. That is, the nanoparticles formed with the double coating layer include nanoparticles; A primary coating layer comprising a silane containing a fluorine group coated on the surface of the nanoparticles; And a secondary coating layer made of a hydrophobic material coated on the surface of the primary coating layer.

In the present invention, the nanoparticles can be used as long as they can be applied to an electrophoretic display or the like. It may also be used as nanocomposites as well as nanoparticles of one metal or nonmetal. In this case, the nanocomposite may be composed of a core-cell structure or a multicore-cell structure.

When used as nanoparticles, the particle size may range from 10 to 1000 nm, preferably from 50 to 500 nm, more preferably from 100 to 300 nm. When used as a nanocomposite, it exhibits a uniform particle size in the range of 50 to 1000 nm, preferably 100 to 500 nm, more preferably 100 to 300 nm. In addition, when a colorant is included, the uniformity of the particles may be more important than the particle size, so that the particle size may be out of the range.

The nanoparticles may be conductive particles, metal particles, organic metal particles, metal oxide particles, magnetic particles, hydrophobic organic polymer particles, photonic crystal characteristics in which regularity is given to arrangement and spacing of particles by application of external energy ≪ / RTI > For example, silicon (Si), titanium (Ti), barium (Ba), strontium (Sr), iron (Fe), nickel (Ni), cobalt (Co), lead (Pb) And may be composed of any one or more of metals of Cu, Ag, Au, W, Mo, Zr and Zr or nitrides or oxides thereof .

The organic material nanoparticles may also be made of a polymer material such as polystyrene, polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, etc., and particles having surface modified with an organic compound having a hydrocarbon group, carboxyl group, ester group, Particles whose surface has been modified by an organic compound having at least one of the group consisting of a halogen atom and an organic group, particles whose surface is modified by a complex compound containing a halogen element, amines, thiols and phosphines, Particles, and particles having charges by forming radicals on the surface.

In addition, the nanoparticles may be particles imparting electric polarization properties. That is, the polarization of the ions or atoms is further induced by the application of an external magnetic field or an electric field for polarization with the medium, so that the amount of polarization is greatly increased. Even when an external magnetic field or an electric field is not applied, The ferroelectric material may have a hysteresis depending on the direction of the ferroelectric material. When an external magnetic field or an electric field is applied, ion or atomic polarization may be further induced to increase the amount of polarization, but an external magnetic field or an electric field is not applied In this case, it may include a superparamagnetic material or a superparamagnetic material in which residual polarization and hysteresis do not remain.

Such materials may include materials having a perovskite structure. That is, as materials having an ABO ₃ structure, materials such as PbZrO ₃ , PbTiO ₃ , Pb (Zr, Ti) O ₃ , SrTiO ₃ , BaTiO ₃ , (Ba, Sr) TiO ₃ , CaTiO ₃ , LiNbO ₃ , .

In addition, the nanoparticles may also be composed of single or heterogeneous metal-containing particles, oxide particles, or photonic crystal particles.

In the case of metals, metal nitrate compounds, metal sulfate compounds, metal fluoroacetoacetate compounds, metal halide compounds, metal perchlorate compounds, metal sulfamate compounds, metal stearate compounds and organometallic compounds And a neutral ligand such as an alkyltrimethylammonium halide-based cationic ligand, an alkyl acid, a trialkylphosphine, a trialkylphosphine oxide, an alkylamine or an alkylthiol, a sodium alkylsulfate, a sodium alkylcarboxylate , Anionic ligands such as sodium alkyl phosphate, sodium acetate, and the like are dissolved in a solvent to prepare an amorphous metal gel, which is then heated to transform the crystalline phase into crystalline particles.

At this time, the magnetic properties of the finally obtained particles can be enhanced by containing a different precursor, or they can be prepared from various magnetic materials such as superparamagnetic, paramagnetic, ferromagnetic, antiferromagnetic, ferrimagnetic, and semi-magnetic.

The present invention is characterized in that a secondary coating layer is formed by sequentially laminating primary and secondary coating layers on the nanoparticles.

The surface of the nanoparticles is coated on the primary coating layer by reacting a fluorine group of a silane containing a fluorine group with a reactor such as a hydroxyl group existing on the surface of the nanoparticles.

Also, the silane containing the fluorine group may have an acidic reactive group. The acid reactive group and the like can be mentioned OH, -SH, -COOH, -CSSH, -COSH, -SO 3 H, -PO 3 H, -OSO 3 H, -OPO 3 H. Such acid reactive groups include

The silane containing fluorine group may also contain a basic charge director such as a succinimide group composed of polyisobutylene succinimide.

The silane containing the fluorine group may be bonded to a positively charged dye or the like, and may include a perfluoroalkyl group.

The silane containing such a fluorine group is preferably a silane having a fluorine group and containing an alkoxy group such as a triethoxy group or a trimethoxy group capable of coating the surface of the particle. The silane containing the fluorine group may be a silane represented by the general formula (1).

Wherein R ₁ to R ₃ may be the same or different and each is a straight or branched alkyl group having 1 to 10 carbon atoms, L ₁ is a straight or branched alkyl group containing 1 to 20 fluorine atoms, Or an alkyl group having 1 to 20 carbon atoms, wherein the substituent includes one or more aryl groups having 6 to 12 carbon atoms, which may or may not contain a substituent, or a cycloalkyl group having 3 to 12 carbon atoms, Or an allyl group having 2 to 20 carbon atoms which does not contain an alkyl group or a combination thereof (the substituent is an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 10 carbon atoms)

Examples of such silanes include (tridecafluoro-1,1,2,2-tetrahydrooctyl) trimethoxysilane, tridecafluoro-1,1,2,2-tetrahydrooctyl trimethoxysilane, Methyl (trifluoromethyl) phenyltrimethoxysilane, (3,3,3-trifluoropropyl) trimethoxysilane, pentafluorophenoxy But are not limited to, pentafluorophenylpropyltrimethoxysilane, pentafluorophenyltrimethoxysilane, pentafluorophenyltrimethoxysilane, pentafluoro (polypropyleneoxy) methoxypropyltrimethoxysilane, pentafluorophenyltrimethoxysilane, (Perfluoro (polypropyleneoxy)] methoxypropyltrimethoxysilane, nonafluorohexyltrimethoxysilane, heptadecafluoro-1,1,2,2-tetrahydrodecyltrimethoxysilane (heptadecafluoro- 1,1,2,2-tetrahydrode cyl trimethoxysilane, 3- (heptafluoroisopropoxy) propyltrimethoxysilane, hexadecafluorododec-11-sen-1-yltrimethoxysilane (hexadecafluorododec-11 -en-1-yltrimethoxysilane), dodecafluorodec-9-ene-1-yltrimethoxysilane, 4-bromo-3,3,4,4- 4-bromo-3,3,4,4-tetrafluorobutyltrimethoxysilane, tridecafluoro-1,1,2,2-tetrahydrooctyltriethoxysilane, 1,1,2,2-tetrahydrooctyl) triethoxysilane, m- (trifluoromethyl) phenyltriethoxysilane, (3,3,3-trifluoropropyl) triethoxy (3,3,3-trifluoropropyl) triethoxysilane, pentafluorophenoxyundecyltriethoxysilane, pentafluorophenylpropyltrimethoxysilane, pentafluorophenylpropyltrimethoxysilane, iethoxysilane, pentafluorophenyltriethoxysilane, perfluoro (polypropyleneoxy)] methoxypropyltriethoxysilane, and nonafluorohexyltriethoxysilane, as well as nonafluorohexyltriethoxysilane, (heptadecafluoro-1,1,2,2-tetrahydrodecyl) triethoxysilane), 3- (heptafluoroisomethyl) heptadecafluoro-1,1,2,2- Heptafluoroisopropoxy propyltriethoxysilane, hexadecafluorododec-11-en-1-yl triethoxysilane, dodecafluoro-1,1- Dodecafluorodec-9-ene-1-yltriethoxysilane, 4-bromo-3,3,4,4-tetrafluorobutyltriethoxysilane (4- bromo-3,3,4,4-tetrafluorobutyltriethoxysilane), but the present invention is not limited thereto.

As described above, the nanoparticles primarily coated with the silane containing a fluorine group are further reacted with a substance containing a hydrophobic functional group to form a secondary coating layer on the surface.

At this time, the material containing the hydrophobic functional group is an organic material or an inorganic material including a hydrocarbon group.

The material containing such a hydrophobic functional group is preferably an organic material or an inorganic material having a hydrocarbon group and containing an alkoxy group such as triethoxy group or trimethoxy group capable of coating the surface of the particle. The silane containing the hydrocarbon group may be a silane represented by the general formula (2).

Wherein R ₁ to R ₃ may be the same or different and each is a linear or branched alkyl group having 1 to 10 carbon atoms, L ₂ is an alkyl group having 1 to 20 carbon atoms, with or without a substituent, Wherein the substituent is one or more aryl groups having 6 to 12 carbon atoms which may or may not contain a substituent or a cycloalkyl group having 3 to 12 carbon atoms with or without a substituent or an allyl group having 2 to 20 carbon atoms Or a combination thereof (the substituent is an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 10 carbon atoms)),

For example, there may be mentioned 11-allyloxyundecyltrimethoxysilane, para-styryltrimethoxysilane, para-tolyltrimethoxysilane, 10-octadecyltrimethoxysilane, N-propyltrimethoxysilane, 7-octenyltrimethoxysilane, n-octyltrimethoxysilane, n-octyltrimethoxysilane, n-octyltrimethoxysilane, Phenethyltrimethoxysilane, 4-phenylbutyltrimethoxysilane, 2-phenylethyltrimethoxysilane, n-octadecyltrimethoxysilane, and the like. ), 11- (2-methoxyethoxy) undecyltrimethoxysilane, isobutyltrimethoxysilane, isooctyltrimethoxysilane, ethyl tri (meth) acrylate, Methoxysilane (ethyltrimeth oxysilane, hexadecyltrimethoxysilane, hexyltrimethoxysilane, n-decyltrimethoxysilane, diphenylmethyl trimethoxysilane, and the like. Dodecyltrimethoxysilane, cyclohexyltrimethoxysilane, cyclooctyltrimethoxysilane, cyclopentyltrimethoxysilane, n-butyltrimethoxysilane (n-butyltrimethoxysilane), n-butyltrimethoxysilane -butyltrimethoxysilane, t-butyltrimethoxysilane, 9-anthracenyltrimethoxysilane, 11-allyloxyundecyltriethoxysilane, para-stearate, Para-styryltriethoxysilane, para-tolyltriethoxysilane, 10-undecenyltriethoxysilane, n-propyltriethoxysilane, N-propyltriethoxysilane, 7-octenyltriethoxysilane, n-octyltriethoxysilane, phenethyltriethoxysilane, 4-phenylbutyltriethoxysilane, (2-phenylethyltriethoxysilane), n-octadecyltriethoxysilane, 11- (2-methoxyethoxy) undecyltriethoxysilane, But are not limited to, 11- (2-methoxyethoxy) undecyltriethoxysilane, isobutyltriethoxysilane, isooctyltriethoxysilane, ethyltriethoxysilane, hexadecyltriethoxysilane, Hexyltriethoxysilane, n-decyltriethoxysilane, (diphenylmethyl) triethoxysilane, dodecyltriethoxysilane, cyclohexylmethoxysilane, and the like. Tree Cyclohexyltriethoxysilane, cyclooctyltriethoxysilane, cyclopentyltriethoxysilane, n-butyltriethoxysilane, t-butyltriethoxysilane, t-butyltriethoxysilane, ), And 9-anthracenyltriethoxysilane. These silanes may be used alone or in combination of two or more.

In addition, a secondary coating layer can be formed by polymerizing a polymer monomer containing an alkyl group using a radical initiator. Such polymeric monomers include acrylates and methacrylates which comprise up to 8 carbon atoms and optionally formed from alcohols containing hydroxyl or halogen or other polar substituents such as carboxyl, cyano, ketone or aldehydes; Acrylamide and methacrylamide; N, N-dialkyl acrylamide; N-vinylpyrrolidone; Styrene and its derivatives; Vinyl esters; Vinyl halide. ≪ / RTI > Specific examples include methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, 2- Acrylamide, acrylic acid, acrylonitrile, methylvinyl ketone, methacrylamide, N-vinylpyrrolidone, styrene, vinyl acetate, vinyl chloride, and vinylidene chloride.

It is also possible to use fluorine-containing esters of acrylic acid and methacrylic acid, such as trifluoroethyl methacrylate, hexafluorobutyl acrylate, or other fluorinated monomers such as pentafluorostyrene or others containing polymerizable functional groups And a polyfluoroaromatic molecule.

Hereinafter, the present invention will be described in detail with reference to Examples and Experimental Examples.

However, the following Examples and Experimental Examples are merely illustrative of the present invention, and the contents of the present invention are not limited by Examples and Experimental Examples.

[Example 1] Preparation of secondary coated nanoparticles

a. Containing a fluorine group With silane  Production of titanium dioxide particles having a primary coating layer formed

1 kg of white titanium dioxide (R706, Dupont Co.) and 2.5 kg of ethanol were put in a 10 L jacket reaction tank, and stirred at a constant speed of 400 rpm to sufficiently wet ethanol on the surface of the particles. Next, it was uniformly dispersed for 2 hours using a media mill (Micromedia, Buhler) filled with 0.65 mm zirconia beads. To the dispersed solution were added 250 g of a 28% aqueous ammonia solution and 350 g of nonafluorohexyltrimethoxysilane in this order, and the temperature was raised to 50 ° C., followed by reaction for 8 hours. When the coating was completed, the particles were collected by a centrifuge and then redispersed in ethanol was repeated three times. The final obtained particle slurry was dried by using a hot-air drier at 100 캜 to obtain particles.

b. Containing a hydrocarbon group With silane  Titanium dioxide particle formation with secondary coating layer

500 g of primary coating particles and 2.5 kg of ethanol were put into a 10 L jacket reaction tank in order and stirred at a constant speed of 400 rpm to make the ethanol sufficiently wet on the surface of the particles. This was uniformly dispersed for 1 hour using a media mill (Micromedia, Buhler) filled with 0.65 mm zirconia beads. 150 g of 28% ammonia aqueous solution and 50 g of dodecyltriethoxysilane were sequentially added to the dispersed solution, and the temperature was raised to 60 ° C, followed by reaction for 12 hours. When the coating was completed, the particles were collected using a centrifuge, and then redispersed using ethanol was repeated three times. Thereafter, the particles were dried by using a hot-air dryer at 100 캜. In this experiment, the length of the hydrocarbon group was different from that of the silane. 7-octenyltrimethoxysilane was used as the silane having the carbon number of 8, and hexadecyltrimethoxysilane was used as the silane having the carbon number of 16.

[Example 2] Production of colored ink using particles having a secondary coating layer formed

a. White Ink Manufacturing

150 g of the secondarily coated nanoparticle powder was put in a 1 L double jacket reaction tank and 200 g of Isopar L, 0.8 100 g of halocarbon oil, 0.75 g of OLOA 11000, 0.75 g of Solseperse, 0.15 g of Span 85 and 300 mL of 0.3 mm zirconia beads were sequentially added, And dispersed at 2500 rpm for 15 hours using a mill (equipment name: dispermat). After the dispersion was completed, the colored ink was removed by filtering to remove the beads.

b. Colored ink manufacturing

To 150 g of halocarbon oil was added 26 g of black dye (solvent black 34) as a coloring dye and dissolved homogeneously at 30 캜. The dissolved dye solution was put in a white ink and mixed uniformly at 25 DEG C for 4 hours.

[Example 3] Microencapsulation of colored ink using secondary coated particles

A 10L double jacketed reaction vessel was equipped with a stirrer and the temperature was raised to 50 ° C. Then, 5L of primary distilled water, 0.2g of dodecyl sulfate sodium salt as a surfactant, 800g of 10% acacia solution and 80g of gelatin Respectively.

While stirring the mixed solution at a constant speed of 400 rpm, 500 g of the colored ink prepared above was added using a funnel to form a uniform emulsion solution. The pH of the emulsion solution thus formed was adjusted to 4.5 while adding a 10% acetic acid solution.

1 L of first distilled water was further added, and the mixture was stirred for 30 minutes. After adding 10 g of glutaric dialdehyde, the temperature of the reactor was lowered to 5 ° C. When the temperature of the reaction vessel was lowered, stirring was continued for 1 hour, then the temperature was raised to 25 ° C, and stirring was continued for 12 hours. After completion of the reaction, the microcapsules were collected using a centrifuge and washed three times with primary distilled water.

The solids content of the collected microcapsule slurry was measured, and then the concentration was adjusted with microcapsules containing 50% of water.

[Example 4] Production of film using microcapsule

A PET film coated with indium tin oxide (ITO) having a sheet resistance of 150? Was prepared. A capsule slurry containing a capsule of 50% solids and 10% of a water-soluble adhesive was uniformly coated on the film to a thickness of 80 탆 using a bar coater. The coated film was placed in a dry oven at 75 캜 for 7 minutes, and then an ITO film coated with a pressure-sensitive adhesive was laminated.

In order to test the effect of the nanoparticles including the dual coating layer, the titanium dioxide nanoparticles containing the double coating layer were dispersed in toluene, which is a non-polar solvent, and then encapsulated. Then, the coagulation of the particles was measured when the electric field was applied inside the capsule.

Also, in order to confirm whether the surface properties of the nanoparticles including the double coating layer and the single coating layer are different, they were dispersed in toluene and then applied to a glass substrate using a spin coater and the surface states of the inks were compared .

Referring to FIG. 2, the titanium dioxide nanoparticles (a) coated with fluorosilane, the titanium dioxide nanoparticles (b) of the double coating layer secondary coated with a hydrocarbon silane having 8 carbon atoms, the hydrocarbon silane having 12 carbon atoms Observation results of the titanium dioxide nanoparticles (d) of the double coated layer of the second coat coated with the tea coatings of the titanium dioxide nanoparticles (c) and the hydrocarbon coatings of the carbon number of 16 (d) revealed that the titanium dioxide nanoparticles ), The dispersibility in the nonpolar solvent was superior to that of the titanium dioxide nanoparticle having a single coating layer, and it was confirmed that the state of the coated surface was good. In addition, it was confirmed that the hydrophobic effect is significantly exhibited when the secondary coating layer is formed of a hydrophobic substance having 12 or more carbon atoms.

The contact angles were also measured to determine the difference in surface characteristics between the titanium dioxide nanoparticles having no coating layer and the primary and secondary surface-coated nanoparticles.

Each of the nanoparticles was dispersed in ethanol at a weight ratio of 50%, and then applied to a 2 cm x 2 cm glass substrate using a spin coater at 2500 rpm for 60 seconds, followed by drying in a hot air drier at 85 캜 for 1 hour. And the contact angle of the interface was measured.

As a result, in the case of the titanium dioxide nanoparticles having no coating layer formed thereon, it is confirmed that the dropped water completely spreads and the contact angle is 0 degrees as shown in FIG. 3 (a). It was also confirmed that the nanoparticles (c) including the double coating layer had a higher contact angle than the nanoparticles (b) containing the single coating layer. This is a result of confirming that the particle surface of the nanoparticles containing the double coating layer of the present invention is more hydrophobic.

Table 1 summarizes the results of this test.

Contact angle (°) Left contact angle (°) Right contact angle (°) a 0 0 0 b 126.86 126.95 126.77 c 133.16 133.26 133.06

As a result of several tests, it was confirmed that the nanoparticles containing the double coating layer of the present invention exhibited a contact angle of 130 ° or more. When a contact angle of not less than the above range is obtained, sufficient dispersibility can be obtained, and it has been understood that the problem of agglomeration when applied to ink is greatly improved.

The surface states of titanium dioxide nanoparticles without coating layer and primary and secondary surface - coated nanoparticles were measured by infrared spectroscopy.

Infrared spectroscopy was performed using a Nicolet iS5 FT-IR spectrometer (Thermo Scientific) and pelletized.

4, unlike the titanium dioxide nanoparticles (a) in which the coating layer was not formed, (b) a band due to the stretching vibration of Si-O appears at 1220 cm ^-1 when a primary coating layer is formed, It can be seen that the band corresponding to the stretching vibration of -F appears at 1062 cm ^-1 .

Also, it can be seen that after the secondary coating, the band corresponding to the stretching vibration of -CH ₂ - and -CH ₃ appears at 2924 and 2856 cm ^-1 .

Since the amount of hydrocarbon molecules on the surface increases when the second coating is performed after the first coating, the band corresponding to the stretching vibration of -CH ₂ - and -CH ₃ increases, and the stretching vibration of the Si- And the band along with it tends to decrease.

Accordingly, it was confirmed that various coating particles were prepared and measured by infrared spectroscopy. As a result, when the following conditions were satisfied, it was confirmed that the coagulation phenomenon according to the ink encapsulation process of the nanoparticles including the double coating layer can be prevented.

① The nanoparticles in the spectrum by the infrared spectroscopy on nanoparticles as the intensity of the absorption bands at 2920 to 2850 to 2860㎝ 2930㎝ ^-1 and ^-1 for the nanoparticles containing the double-coated layer comprising the dual coating layer (2) the intensity of the absorption band at 1060 to 1070 cm ^-1 for the nanoparticle including the double coating layer and the nanoparticle in the spectrum by the infrared spectroscopy is higher than that of the nanoparticle containing the double coating layer Which is 20 to 30% larger than the nanoparticles.

The particle size distribution of the titanium dioxide nanoparticles formed with the single coating layer and the titanium dioxide nanoparticles formed with the double coating layer were measured to find the conditions for securing the dispersibility of the nanoparticles.

5 is a graph of particle size distribution of the titanium dioxide nanoparticles (a) forming the primary coating layer of fluorosilane and the titanium dioxide nanoparticles (b) of the double coating layer in which the secondary coating layer is formed with the hydrocarbon silane. The particle size distribution was measured by using Nano ZS (Malvern) as a particle size analyzer by dynamic light scattering method and measuring 0.002% by weight of a sample dispersed in an organic solvent for dispersion, Isopar M.

Table 2 summarizes the measurement results.

a b Z-Average (nm) 705.5 636.3 Pd Index 0.180 0.285 Polydispersity (nm) 299.5 339.8 % Polydispersity 42.5 53.4 D50 (nm) 677 494 D90 (nm) 1040 641 D95 (nm) 1160 686

The results of the analysis show that there is no significant difference in the average particle size of nanoparticles including a single coating layer and the double coating layer but the size of the particles corresponding to D90 is 1 μm or more in the case of nanoparticles containing a single coating layer Whereas it is 641 nm for the nanoparticles containing the double coating layer.

These results show that nanoparticles aggregate in the nonpolar solvent and do not form secondary particles. As a result, the dispersibility of nanoparticles containing the double coating layer of the present invention is remarkably improved and aggregation in the nonpolar solvent is hardly occurred I do not want to.

As a result of particle size analysis for various coating particles, it was confirmed that when the difference between D90 and D50 in the particle size distribution by the dynamic light scattering method is 200 nm or less, aggregation phenomenon according to the ink encapsulation process of the nanoparticles can be prevented. That is, the result according to the particle size distribution satisfies the range of D90 and D50 within the range of 200 nm or less in a state of being dispersed in the nonpolar solvent, so that the particle size is uniform, and there is no agglomeration among the particles in the solvent, It can be an index indicating the suitability to the following.

In addition, it can be judged whether or not the double coating layer is efficiently formed by measuring the Z-average according to the particle size distribution of the first coated nanoparticles and the second coated nanoparticles. In other words, the Z-average value should differ by more than 65nm from the particle size of the nanoparticles after the first coating and the second coating. When the difference is 65 nm or less, it is suggested that the degree of dispersion of the particles by the secondary coating is not sufficiently improved. As a result, this is an index indicating that the double coating layer can not be uniformly formed in the secondary coating process. Thus, by analyzing the primary coating particles in the intermediate state during the manufacturing process, it is possible to determine whether the secondary coating process has been completed and whether there is a defective process.

Next, the ink prepared through the nanoparticles containing the double coating layer of the present invention will be described.

In the present invention, the ink is an ink including nanoparticles containing a double coating layer, a dye and a solvent.

Such inks include the steps of preparing a dispersion medium in which nanoparticles, dyes, and solvents containing a double coating layer are dispersed; And microencapsulating the dispersion medium.

At this time, the solvent may be water-soluble and / or non-water-soluble for daily use. In this case, the water-soluble solvent may be selected from the group consisting of water, alcohols, ethylene glycol, and mixtures thereof. Examples of the water-insoluble solvent include halogenated hydrocarbons, halogenated hydrocarbon oils, Can be selected from the group. In addition, a halogenated organic solvent, a saturated linear or branched hydrocarbon, a silicone oil, and a low molecular weight halogen-containing polymer may be used, and in particular, cyclohexane, tetrachlorethylene or toluene or a mixture thereof may be used.

It is useful that the solvent has a low dielectric constant of about 1 to 10, a high volume resistivity, a low viscosity, a high specific gravity, and a low reflection index. In addition, it may further include a surface modifier for modifying the surface energy of the nanoparticles, charge, a stabilizer for improving particle agglomeration prevention and mobility.

The dyes can be various dyes such as azo dyes, anthraquinone dyes, triphenylmethane dyes and the like depending on the desired color of the ink. Usually, organic dyes can be used. Organic dyes generally can be selected from the group of azo, anthraquinone, and triphenylmethane type dyes. The azo dyes include Oil Red dyes, and Sudan Red and Sudan Black series dyes. Oil blue dyes and Macrolex Blue series dyes can be used as anthraquinone dyes. As the triphenylmethane dye, Michler's hydrol, Malachite Green, Crystal Violet and Auramine O can be used.

Inorganic dyes as the coloring agents can be added to the coloring material such as barium sulfate, zinc oxide, lead sulfate, yellow lead, zinc sulfur, bengale (red iron oxide (III)), cadmium red, , Cobalt green, umber, titanium black, synthetic iron black, titanium oxide, and iron tetraoxide, metal sulfide powder, metal powder and the like. The inorganic dyes can be used in combination with organic dyes in order to optimize the saturation and lightness and ensure good application, sensitivity, developability and the like.

Further, a coloring composition may be used in place of the dye. The coloring composition is a mixture of the above-mentioned organic or inorganic coloring materials mixed with a coloring material carrier comprising a transparent resin, a precursor thereof or a mixture thereof. Here, the transparent resin includes a thermoplastic resin, a thermosetting resin and a photosensitive resin, and the precursor thereof includes a monomer or oligomer which is cured by irradiation with radiation to produce a transparent resin, and these may be used singly or in combination of two or more . The colorant carrier is preferably used in a proportion of 10 to 90% by weight, more preferably 20 to 80% by weight, based on the total solid content of the coloring composition.

The ink prepared through the step of microencapsulating the dispersion medium is formed into microcapsules.

Such microcapsules can be prepared through a reaction process of core-shell structuring by using a dispersion medium as a core material.

First, in the dispersion medium of nanoparticles and pigments, the nanoparticles and the pigment may be dispersed in a proportion of 0.1 to 25% by weight based on the total amount of the dispersion medium, but they may be dispersed in a larger amount if necessary. The dispersion of the core material is dispersed using an ultrasonic disperser or a homogenizer.

Next, the prepolymer is prepared by adjusting the acidity by mixing the polymer forming the wall material of the microcapsule. This step can be carried out simultaneously with the step of producing the dispersion medium.

The polymer for forming the wall material may be a polymer precursor having a low elasticity and hardness, such as a urea-formaldehyde, a melamine-formaldehyde, a copolymer such as methylvinylether-maleic anhydride, a gelatin, It is possible to use polymers such as alcohol, polyvinyl acetate, cellulose derivatives, acacia, carrageenan, carboxymethyllellulose, hydrolyzed styrene anhydride copolymer, agar, alginate, casein, albumin and cellulose phthalate. By controlling the hydrophilicity and hydrophobicity of such a polymer, a wall material can be formed surrounding the dispersion medium. The prepolymer may be dispersed in a dispersion medium to prepare a dispersion.

Next, the prepolymer dispersion of the dispersion medium and the wall material may be mixed and stirred to form an emulsion. As a condition for forming such an emulsion, it is necessary to optimize the ratio of the dispersion medium and the prepolymer, and the two dispersions may be mixed in a volume ratio of 1: 5 to 1:12. Further, a stabilizer may be added to improve dispersibility. In the emulsion, the nanoparticles comprising the double coating layer can be in a dispersed phase and the wall material can be in a continuous phase.

Further, an additive may be added to enhance the stability of the emulsion. Such an additive may be an organic polymer having high viscosity and high wettability after dissolution in an aqueous phase. Specific examples thereof include gelatin, polyvinyl alcohol, sodium carboxymethylcellulose, starch, hydroxyethylcellulose, polyvinylpyrrolidone, alginate May be used.

The pH and temperature of the emulsion thus formed can be adjusted so that the continuous phase wall material dispersion is deposited around the ink, which is a dispersion phase, to form the walls of the capsule, thereby encapsulating the core material dispersion. That is, the encapsulation is carried out by the in situ polymerization method. In this case, it may include a step of adding the additive to increase the hardness of the wall material by making the capsule wall material more densely and reducing the elasticity.

The type of additive to be added may be an ionic or polar material that is soluble in the aqueous phase. For example, at least one of curing catalysts such as ammonium chloride, resorcinol, hydroquinone, and catechol can be used.

The microcapsule-type ink of the present invention can be produced by the in-situ polymerization method as described above, but may also be produced by a coacervation approach or interfacial polymerization.

In the case of the coacervation method, the inner phase and the outer phase / oil phase emulsion are used. Colored nanocomposite colloids are coagulated (bulked) out of the aqueous external phase, and controlled by temperature, pH, relative concentration, etc., to form a wall material in the inner liquid droplet. In the case of coacervation, as the wall material, gelatin, arabic rubber and the like can be used.

In the case of the interfacial polymerization method, an aqueous emulsion is present as an emulsion in the presence of lipophilic monomers on the inner surface. The monomer in the liquid crystal adhered to the aqueous external phase reacts with the monomer, and a polymerization reaction takes place at the interface between the internal liquid phase and the surrounding aqueous external phase, and a wall of the particle is formed around the liquid phase. The formed wall is relatively thin and permeable, but unlike other manufacturing methods, heating is not required, and thus it is advantageous to apply various dielectric liquids.

The microcapsule according to the present invention has a uniform spherical shape of 10 to 100 탆, preferably 10 to 50 탆, more preferably 10 to 40 탆. This uniformity of capsule shape and size causes macroscopic homogeneity of the nanoparticles to be ensured, thereby changing the color and enhancing the sharpness of colors to be realized. If the uniformity of shape and size of the microcapsule is not ensured, even if the nanoparticles dispersed in the microcapsules are uniformly rearranged, macroscopic irregularity increases, and the color change and implementation become insufficient.

To verify the effect of the nanoparticles containing the double coating layer of the present invention when applied to an ink, the electrophoresis of the film was observed.

Fig. 6 is a graph showing the results obtained by using microcapsules (a) containing titanium dioxide nanoparticles coated with fluorosilane and microcapsules (b) containing titanium dioxide nanoparticles of a double coating layer secondary coated with 12 carbon atoms of hydrocarbon silane Showing the electrophoretic property when an electric field is applied to the film. A black dye was used as a dye, and electrophoretic properties of nanoparticles in microcapsules were compared by applying a voltage of 15 V to the film. The photograph before the authorization is the upper photograph, and the photograph when the authorization is the lower photograph.

Comparing the photographs of the white state, the nanoparticles containing the double coating layer of the present invention were found to have less aggregation of particles inside the capsule than the primary coated nanoparticles. This can be confirmed from the fact that the color of the lower dye is less visible.

The ink prepared by using the nanoparticles containing the double coating layer of the present invention is a microcapsule which can be applied to various types of printing since it has no aggregation during drying and storage and has excellent thermal stability and wall strength, It is possible to apply the present invention to inks that require heat resistance and cohesion resistance.

When the microcapsule according to the present invention is applied to an ink for printing, it may be dispersed in a binder such as a water-soluble polymer, an water-dispersible polymer, an oil-soluble polymer, a thermosetting polymer, a thermoplastic polymer, a UV-curable polymer or a radiation curable polymer. A surfactant and a crosslinking agent may be added to such a binder to improve the durability of the printing or coating process.

The printing using the microcapsules includes all forms of printing and coating, and coatings such as roll coating, gravure coating, immersion coating, spray coating, meniscus coating, spun coating, brush coating and air knife coating, Printing, electrostatic printing, thermal printing, or inkjet printing.

For example, it can be manufactured with various display devices such as color variable glass, color variable wallpaper, color variable solar cell, color variable sensor, color variable paper, color variable ink, etc., do. The method of displaying a color can be various color display by causing a change of color using a medium generating an electric field, maintaining a changed color state, or returning to an original color when an electric field is removed.

In addition, a barrier rib may be formed by a roll-to-roll method, and a display material including the microcapsule of the present invention may be injected into the color display device.

In addition, the present invention can be applied to a reflective display device using two or more kinds of microcapsules having different threshold values for an electric field. That is, microcapsules having different colors can be placed on a reflective display device divided into upper and lower substrates and barrier ribs including upper and lower electrodes, and various colors can be realized by applying an electric field.

In addition, a solution containing the microcapsule of the present invention may be coated on a light-transmitting film and cured to prepare a film.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken in conjunction with the present invention. Variations and changes are possible. Such variations and modifications are to be considered as falling within the scope of the invention and the appended claims.

10: nanoparticle 20: primary coating layer
30: secondary coating layer

Claims (9)

A microcapsule comprising nanoparticles and a solvent comprising a dual coating layer,
The nanoparticles comprising the double coating layer may be formed,
Nanoparticles;
A primary coating layer comprising a silane containing a fluorine group coated on the surface of the nanoparticles;
And a secondary coating layer composed of a material containing a hydrophobic functional group coated on the surface of the primary coating layer.
The method according to claim 1,
Wherein the microcapsule comprises a dye.
The method according to claim 1,
Wherein the fluorine-containing silane is a silane according to the following formula (1).
[Chemical Formula 1]

Wherein R ₁ to R ₃ may be the same or different and each is a straight or branched alkyl group having 1 to 10 carbon atoms. L ₁ is an alkyl group having 1 to 20 carbon atoms and 1 to 20 carbon atoms and containing or not having a substituent and wherein the substituent is selected from the group consisting of one or more aryl groups having 6 to 12 carbon atoms Or a cycloalkyl group having 3 to 12 carbon atoms or a substituted or unsubstituted allyl group having 2 to 20 carbon atoms which may or may not contain a substituent, or a combination thereof (the substituent is preferably an alkyl group having 1 to 5 carbon atoms or An alkenyl group having 2 to 10 carbon atoms.
The method according to claim 1,
Wherein the material containing the hydrophobic functional group is an organic or inorganic material containing a hydrocarbon group.
The method of claim 4,
Wherein the substance containing the hydrophobic functional group is a silane containing a hydrocarbon group.
The method of claim 5,
Wherein the hydrocarbon group-containing silane is a silane according to the following formula (2).
(2)

Wherein R ₁ to R ₃ may be the same or different and each is a straight or branched alkyl group having 1 to 10 carbon atoms. L ₂ is an alkyl group having 1 to 20 carbon atoms, with or without a substituent, wherein the substituent is one or more aryl groups having 6 to 12 carbon atoms with or without a substituent or a carbon number A cycloalkyl group having from 3 to 12 carbon atoms or an allyl group having from 2 to 20 carbon atoms having no substituent or a combination thereof (the substituent is an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 10 carbon atoms) ]
Preparing a dispersion medium for dispersing the nanoparticles and the solvent comprising the double coating layer of claim 1;
Microencapsulating the dispersion medium;
Wherein the method comprises:
The method of claim 7,
Wherein the dispersion medium comprises a dye.
The method of claim 7,
The nanoparticles comprising the double coating layer may be formed,
Coating the surface of the nanoparticles with a silane having a fluorine functional group;
Coating a surface of the first surface-coated particle with a hydrophobic substance on the surface of the first surface-coated particle.

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