KR20170120886A - HIGH REFRACTIVE TiO2 AND METHOD OF PRODUCING A HIGH REFRACTIVE DISPERSION USING THE SAME - Google Patents

Abstract

In the present invention, provided are rutile crystal-form high refractive index titanium dioxide (TiO_2) particles which are formed by coating one or more oxides selected from ZrO_2, Nb_2O_5, SnO_2, ZnO, CeO_2, and La_2O_3 on the surface of TiO_2 particles, and have an average particle diameter of 10 nm or less; and a method of producing a dispersion of the same. According to the present invention, the particles, the dispersion, and a display sheet using the same use TiO_2 with a high refractive index, and are prevented from becoming cloudy from photoactivity, by using an oxide containing zirconia on the surface of TiO_2, and thus can be used to provide a layer having a high refractive index necessary for manufacturing display devices and in particular, flexible display devices.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a high refractive index TiO2 and a method of producing a high refractive index dispersion using the same,

The present invention relates to a high-index TiO ₂ having a rutile crystal structure, a high-refractive index dispersion using the same, a method for producing the same, and a display using the dispersion.

Titanium oxide is used as a photocatalyst and is one of the most basic materials, and has been widely used in a wide range of materials such as paint, fiber, rubber, paper, cosmetics and food. That is, an oxide semiconductor called titanium oxide has a property of being activated when it receives light energy from the beginning. Activity can be said to be a chemical change prone to occur. In the case of using as a white pigment or an ultraviolet absorber of cosmetics, it has been a long-term problem to suppress this photoactivity. In any case, the photoactivity makes it tangential to contact with it, causing a chalking phenomenon that produces white powder like chalk.

On the other hand, organic substrates have been widely used for liquid crystal display devices, organic EL display device substrates, color filter substrates, solar cell substrates, and the like. However, the glass substrate has a limitation in thickness and weight of the liquid crystal display device due to its thick thickness and heavy weight, and has a problem that it is vulnerable to impact resistance. In addition, the brittleness of the glass material was not suitable for use as a display substrate. As a result, a flexible substrate made of a plastic optical film material has attracted attention as a substitute for conventional glass substrates. The flexible substrate has characteristics suitable for liquid crystal displays, next generation display devices such as organic EL, electronic paper, and the like. However, a flexible substrate made only of a plastic composite sheet has a problem of not only a high coefficient of thermal expansion but also a low rigidity. Accordingly, a method of fabricating a composite sheet by supplementing stiffness by impregnating a matrix resin, which is a polymer material, with a reinforcing material including glass fiber or glass cloth is used. On the other hand, in order to use the composite sheet as a flexible substrate, transparency must be increased in order to provide the surface performance of the display in addition to mechanical properties such as rigidity, heat resistance and flexibility. In order to improve the transparency by matching the refractive index with the glass fiber used as the reinforcing material in the conventional composite sheet, an aromatic group is introduced into the resin contained in the matrix. However, in this case, although the refractive index can be increased at a specific wavelength, the refractive index is not increased at the entire wavelength range where the composite sheet is used. Particularly, the refractive index matching with the reinforcing material at the entire wavelength range is not satisfactory and good transparency can not be obtained.

The present invention relates to a method for preventing the discoloration (suppression of photoactivity) of Rutile TiO ₂ particles after synthesis of Rutile crystal particles having an average particle diameter of 10 nm or less by using raw materials such as TiCl ₄ , TiOCl ₂ , Ti (SO ₄ ) ₂ , TiPT and TnBT The object of the present invention is to coat a surface with a material having a high refractive index and to apply the dispersion to a display in a high concentration / high transparency.

Another object of the present invention is to provide a composite sheet which can provide good transparency.

It is still another object of the present invention to provide a flexible substrate and a display device including the composite sheet.

In order to solve the above problems, titanium-based fine particles having a rutile crystal structure are used to form a curable coating film for display having high refractive index, weather resistance and light resistance. In order to prevent photoactivity, particles And a dispersion thereof.

The present invention relates to a TiO ₂ particle having a mean particle diameter of 10 nm or less and a rutile crystalline high-refractive-index TiO ₂ particle coated with at least one oxide selected from ZrO ₂ , Nb ₂ O ₅ , SnO ₂ , ZnO, CeO ₂ and La ₂ O ₃ Is produced. The Rutile crystalline high-refractive-index TiO ₂ particles are synthesized from one selected from TiCl ₄ , TiOCl ₂ , Ti (SO ₄ ) ₂ , TiPT and TnBT. In order to prepare a high concentration, highly transparent dispersion, .

When the prepared rutile crystalline high-refractive-index TiO ₂ particles are exposed to ultraviolet rays after being coated on rmeofhh display or the like, they are discolored due to photoactivity, so that it is difficult to maintain a high refractive index. Therefore, in order to prevent this, the surface should be coated with a material having a high refractive index to maintain transparency and high refractive index. Accordingly, at least one oxide selected from ZrO ₂ , Nb ₂ O ₅ , SnO ₂ , ZnO, CeO ₂ and La ₂ O ₃ is coated on the surface of the TiO ₂ particles.

The coated oxide is characterized by 1 to 50 wt% of TiO ₂ particles. When the amount of the coating is less than 1 wt%, it is difficult to suppress the photoactivity, and when it exceeds 50 wt%, the TiO ₂ particles can not exhibit their inherent functions.

As described above, the refractive index of TiO ₂ particles coated with oxide is 2.5 to 2.7, which is dispersed at a high concentration / high transparency and can be applied to a display.

High-index TiO manufacturing method of the _second particle of the present invention are TiCl _4, TiOCl _2, Ti (SO _{4) 2,} TiPT, a carboxylic acid, oleic acid, or stearic acid TiO ₂ with heating after mixing the deionized water in the aqueous solution is selected from TnBT Adding 1 to 10 wt% of the product to the reaction mixture;

After completion of the reaction, the pH is neutralized to 6 to 8 with NaOH, and the solution is washed with ultrapure water to completely remove Na + and Cl- ions and dried at 100 to 130 ° C. for 10 to 14 hours to obtain Rutile TiO ₂ ;

The synthesized Rutile TiO ₂ Is coated with at least one oxide selected from ZrO ₂ , Nb ₂ O ₅ , SnO ₂ , ZnO, CeO ₂ and La ₂ O ₃ while being dispersed in ethanol and ultrapure water and stirred.

Another aspect of the present invention is to provide a high refractive index TiO ₂ The particle powders are mixed with MEK or PGME solvent, a dispersant is added thereto, and the dispersion is dispersed using a 0.03 to 0.07 mm bead mill to produce a highly concentrated and highly transparent dispersion having an average particle size of 20 to 30 nm.

A rutile crystal phase having an average particle size of 10 nm or less coated with at least one oxide selected from ZrO ₂ , Nb ₂ O ₅ , SnO ₂ , ZnO, CeO ₂ and La ₂ O ₃ on the surface of the TiO ₂ particles produced according to the above- The dispersion containing the refractive index TiO ₂ particles can be applied to a high-refractive-index hard coating of a display (flat plate, flexible), an antireflection film, a prism sheet or the like.

In order to prevent discoloration (suppression of photoactivation) of Rutile TiO ₂ particles, it is intended to coat the surface with a material having a high refractive index and disperse it in a high concentration / high transparency for display.

Therefore, the particles and the dispersion according to the present invention and the display sheet to which the particles and the dispersion are applied have high refractive index of TiO ₂ It is possible to provide a sheet having a high refractive index necessary for the production of a display, in particular, a flexible display, by using an oxide containing zirconia on the surface of TiO ₂ in order to prevent it from becoming cloudy due to photoactivity.

1 is a schematic diagram of a method for producing TiO ₂ (5 nm, Rutile).
2 is a TEM of TiO ₂ (5 nm, Rutile) particles prepared according to the schematic diagram of FIG.
3 is a photograph showing the result of measurement of TiO ₂ XRD produced according to the schematic diagram of FIG.
4 is a TEM of TiO ₂ coated ZrO ₂ .
FIG. 5 is a photo of the photoactive blocking performance of the particles of FIG. 5.
Figure 6 is a schematic view of the high concentration / high transparency dispersing step of the ZrO ₂ coated TiO ₂ particles.
7 is a photograph showing the final dispersion and the average particle size distribution.
8 is a photograph of (A) SG-T10SMK (B) SG-T025PSMK containing Ink.
9 is a view showing the structure of the AR film of three layers.
10 is a high-index TiO ₂ Lt; / RTI > shows the result of the photoactive test of the solution.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Example  One. TiO ₂ (5 nm, Rutile ) Produce

In order to prepare Rutile crystalline high-refractive-index TiO ₂ particles having an average particle size of 10 nm or less according to the present invention, ultrapure water is mixed with 40% aqueous solution selected from TiCl ₄ , TiOCl ₂ , Ti (SO ₄ ) ₂ , TiPT and TnBT, , Oleic acid, or stearic acid is added in an amount of 1 to 10 wt% based on the TiO ₂ product. When the reaction is completed, the pH is neutralized to 6 to 8 with NaOH and then washed with ultrapure water to completely remove Na + and Cl - And dried at 100 to 130 ° C for 10 to 14 hours.

In the examples, TiOCl ₂ 400 g of ultrapure water is mixed with 100 g of 40% (Titanium Oxychloride Aqueous Solution) and heated. Carboxylic acid (oleic acid, stearic acid, etc.) is added in an amount of 1 ~ 10 wt% based on the TiO ₂ product while heating, and the mixture is kept at 65 ° C for 2 hours. Rutile TiO ₂ of similar size can be obtained without the addition of Carboxyl Acid, but if not added, secondary aggregation of the particles is severe. After the reaction is completed at 65 ° C for 2 hours, the pH is adjusted to 6-8 with NaOH and the Na + and Cl- ions are completely removed using ultrapure water. After the rinsing was completed and dried at 120 ° C. for 12 hours, 5 nm-grade Rutile TiO ₂ was obtained (no heat treatment was necessary).

* Raw material

TiOCl ₂ 40%: Millennium Chemicals

Oleic Acid: DAE JUNG

Stearic Acid: DAE JUNG

NaOH: DUKSAN

As a result of the TEM measurement, it was confirmed that the primary particles were very uniform (about 5 to 10 nm) (FIG. 2) and the Rutile Phase as an XRD measurement (FIG. 3).

Table 1 below shows other data.

TO15R Remarks Crystal form rutile XRD Surface area (m2 / g) 163.1348 BET Whiteness 91.20 Spectrophotometer additive Carboxy acid -

TiO ₂ is advantageous in the rutile phase having the highest refractive index, and in order to produce a high concentration / high transparency dispersion, the particle size should basically be 10 nm or less for the dispersion process.

Example  2. TiO ₂ on ZrO ₂  coating

In order to suppress the optical activity, which is an important characteristic of TiO ₂ itself, the refractive index should be maintained as high as possible by coating the TiO ₂ surface with an oxide having a high refractive index. The reason why the optical activity should be suppressed in this way is to prevent discoloration when the display is exposed to ultraviolet rays after coating. Accordingly, the present invention relates to a process for preparing the synthesized Rutile TiO ₂ Is dispersed in ethanol and ultrapure water and is coated with at least one oxide selected from ZrO ₂ , Nb ₂ O ₅ , SnO ₂ , ZnO, CeO ₂ and La ₂ O ₃ while stirring.

For the photoactive block, and maintaining high refractive index of TiO ₂ may be coated with _{ZrO 2, Nb 2 O 5,} SnO 2, ZnO, CeO 2, at least one oxide selected from La ₂ O ₃ in the TiO ₂ core. The procedure for coating zirconia on the 5 to 10 nm Rutile TiO ₂ synthesized in Example 1 was as follows.

100 g of TiO ₂ is dispersed in 500 g of ethanol and 500 g of ultrapure water and stirred. While stirring, ZrOCl ₂ Add the solution and calibrate the final pH to 4-5 using NH ₄ OH. ZrO ₂ can be coated to 1 ~ 50wt% compared to TiO ₂ . After keeping for 2 hours, rinse and dry. After drying, it was heat treated at 800 ℃ to impart zirconia crystallinity.

1) As a result, referring to TiO ₂ @ZrO ₂ (TEM) (FIG. 4), ZrO ₂ is thinly coated on TiO ₂ .

2) Evaluation of optically active blocking performance

The photoactivity was confirmed using the vitamin C derivative (ASCORBYL PALMITATE) of the particle.

On the left side of Fig. 4, the photoactivity was suppressed by coating zirconia on Anatase TiO ₂ (Non coating), Rutile TiO ₂ (Non coating) on the middle, and Rutile TiO ₂ on the right.

3) Accelerated weathering test (TiO ₂ coated film color change)

As shown in FIG. 5, even when exposed to Xenon Arc for 62 hours, it was confirmed that there was almost no color change.

Example  3. TiO ₂ @ZrO ₂  High concentration / High transparency High dispersion

When dispersing the TiO ₂ @ZrO ₂ particles, the selection of a surfactant and a dispersing agent is important. In order to disperse TiO ₂ coated with zirconia, the powder was mixed with a solvent, and an appropriate amount of a dispersant was added, followed by dispersion using a beads mill. The beads were dispersed using a bead size of 0.05 mm. As a result, a titania dispersion having a high refractive index with a final average particle size of 20 to 30 nm was obtained (see FIG. 6).

7 shows the final dispersion (solid content 20 wt%) and the average particle size distribution (21.3 nm).

It can be applied to a high-index heart coating, an antireflection film, a prism sheet, etc. of a display (flat panel, flexible).

Hereinafter, evaluation results of TiO ₂ dispersion are shown through experiments.

Experimental Example 1.TiO ₂  Evaluation result of dispersion

1) Ink formulation: TiO ₂ / Acrylic resin / Photoinitiator / MEK,

2) Film production method: spin coat-> prebake (70 ° C, 30 sec) -> UV exposure

SG-T10SMK -> SG-T025PSMK

· L *, b *: direction in which the color change is inverted

           The amount of change of L * was greatly increased.

· A *: The amount of change increased.

? Eab * was increased and the light resistance was not improved.

The photograph of FIG. 8 is a photograph of the SG-T025PSMK dispersion, showing turbidity.

Experimental Example  2. TiO ₂  Evaluation result of dispersion

Ink preparation: TiO2 dispersion / UV resin / photoinitiator / solvent, substrate: glass

Film manufacturing method: spin coating -> vacuum drying -> UV exposure -> baking

UV irradiation conditions: UV lamp -> Xenon, irradiation time -> about 70 hours

* 1 SG-TORF58NS: UV resin included, * 2 SG-TORF58NS coated PET film sample

Table 3 shows evaluation results of a single layer including TiO ₂ & ZrO ₂ (Ft = 150 to 160 nm).

· RWSMK: Light fastness is better than TiO2 dispersion

· RF58NS: the greater the amount Δb *.

· Film: high and low haze

FIG. 9 shows a structure of a three-layer AR film, which is a film on which a hard coat layer, a high refracting layer and a low refracting layer are sequentially placed on a glass substrate. Table 4 shows the evaluation results of the three-layer AR film including a high refractive layer including TiO ₂ and ZrO ₂ .

· SG-TO5 -> light resistance is superior to conventional TiO _2.

· RF58NS -> High haze (target value: less than 0.2). The amount of Δb * is large.

It can be seen from the above Examples and Experimental Examples that the high refractive index TiO ₂ of the present invention and the high refractive index dispersion prepared by using the high refractive index TiO ₂ of the present invention are suitable for a substrate such as a display due to its high refractive index and high transparency.

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 by way of limitation, The present invention may be modified in various ways. Therefore, the present invention is not limited to the above embodiments.

Claims (7)

On the surface of the TiO ₂ particles, _{ZrO 2, Nb 2 O 5,} SnO 2, ZnO, CeO 2, Rutile crystal phase high-index TiO ₂ particles have a mean particle size of 10nm or less coated with at least one oxide selected from La ₂ O _3. The particle according to claim 1, wherein the TiO ₂ particle has a refractive index of 2.5 to 2.7. The particle of claim 1, wherein the coated oxide is 1-50 wt% of TiO ₂ . The particle according to claim 1, wherein the Rutile crystalline high refractive index TiO ₂ particles are synthesized from one selected from TiCl ₄ , TiOCl ₂ , Ti (SO ₄ ) ₂ , TiPT, and TnBT. Adding ultrapure water to an aqueous solution selected from TiCl ₄ , TiOCl ₂ , Ti (SO ₄ ) ₂ , TiPT and TnBT, and adding 1 to 10 wt% of carboxylic acid, oleic acid or stearic acid to the TiO ₂ product ;
After completion of the reaction, the pH is neutralized to 6 to 8 with NaOH, and the solution is washed with ultrapure water to completely remove Na + and Cl- ions and dried at 100 to 130 ° C. for 10 to 14 hours to obtain Rutile TiO ₂ ;
The synthesized Rutile TiO ₂ Is coated with at least one oxide selected from ZrO ₂ , Nb ₂ O ₅ , SnO ₂ , ZnO, CeO ₂ and La ₂ O ₃ while dispersing in ethanol and ultrapure water and stirring, (Method for producing high refractive index TiO ₂ particles). A process for producing a high-concentration and high-transparency dispersion liquid, which comprises mixing the particle powders of any one of claims 1 to 4 in a MEK or PGME solvent, adding a dispersant, and dispersing the particles so as to have an average particle size of 20 to 30 nm by using a 0.03 to 0.07 mm bead mill Gt; Wherein the surface of the TiO ₂ particle is coated with one or more oxides selected from ZrO ₂ , Nb ₂ O ₅ , SnO ₂ , ZnO, CeO ₂ and La ₂ O _3, and Rutile crystalline high-refractive-index TiO ₂ particles having an average particle size of 10 nm or less Dispersant.

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