CURABLE COMPOSITION AND OPTICAL MATERIAL

Abstract

A curable composition for forming a high refractive index optical material, the curable composition comprising an episulfide compound; sulfur-containing organic particles comprising a specific content of sulfur atoms; and a reducing agent, and an optical material comprising the curable composition.

Claims

1. A curable composition for forming a high refractive index optical material, the curable composition comprising an episulfide compound; sulfur-containing organic particles comprising 60 to 80 wt % of sulfur atoms; and a reducing agent.

2. The curable composition according to claim 1, wherein the weight ratio of the episulfide compound to the sulfur-containing organic particles comprising 60 to 80 wt % of sulfur atoms is 1:0.01 to 0.5.

3. The curable composition according to claim 1, wherein the sulfur-containing organic particles comprising 60 to 80 wt % of sulfur atoms comprise repeat units represented by the following Chemical Formula 1: ##STR00007## in Chemical Formula 1, n is an integer of 1 to 10, and m is an integer of 1 to 1000.

4. The curable composition according to claim 1, wherein the sulfur-containing organic particles comprising 60 to 80 wt % of sulfur atoms have particle diameters of 20 to 300 nm.

5. The curable composition according to claim 1, wherein the episulfide compound is represented by the following Chemical Formula 2: ##STR00008## in Chemical Formula 2, R.sub.1 and R.sub.2 are each independently hydrogen or C1-C10 alkyl, R.sub.3 and R.sub.4 are each independently a single bond or C1-C10 alkylene, a is an integer of 0 to 4, and b is an integer of 0 to 6.

6. The curable composition according to claim 1, wherein the episulfide compound comprises at least one selected from the group consisting of bis(β-epithiopropyl)sulfide, bis(β- epithiopropyl)disulfide, bis(β-epithiopropylthio)methane, 1,2-bis(β- epithiopropylthio)ethane, 1,3-bis(β-epithiopropylthio)propane, and 1,4-bis(β- epithiopropylthio)butane.

7. The curable composition according to claim 1, wherein the reducing agent is included in the amount of 0.1 to 15 wt %, based on 100 wt % of the total curable composition.

8. The curable composition according to claim 1, wherein the reducing agent comprises at least one selected from the group consisting of triphenylphosphine (PPh.sub.3), tris(2-carboxylethyl)phosphine (TCEP), 1,4-dimercaptobutane-2,3-diol (DTT), tris(3-hydroxypropyl)phosphine (THPP), beta-mercaptoethanol (BME) and dithiobutylamine (DTBA).

9. An optical material comprising: an episulfide compound; sulfur-containing organic particles comprising 60 to 80 wt % of sulfur atoms; and a reducing agent.

10. The optical material according to claim 9, wherein the optical material has a glass transition temperature of 80° C. or more, and the optical material has a refractive index of 1.710 or more.

11. The optical material according to claim 9, wherein the sulfur-containing organic particles comprising 60 to 80 wt % of sulfur atoms comprise repeat units represented by the following Chemical Formula 1: ##STR00009## in Chemical Formula 1, n is an integer of 1 to 10, and m is an integer of 1 to 1000.

12. The optical material according to claim 9, wherein the episulfide compound is represented by the following Chemical Formula 2: ##STR00010## in Chemical Formula 2, R.sub.1 and R.sub.2 are each independently hydrogen or C1-10 alkyl, R.sub.3 and R.sub.4 are each independently a single bond or C1-10 alkylene, a is an integer of 0 to 4, and b is an integer of 0 to 6.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0068] FIG. 1 is a photograph of the polysulfide aqueous solution prepared in Preparation Example, taken by scanning electron microscope.

[0069] FIG. 2 is a photograph of the sulfur-containing organic particles prepared in Preparation Example, taken by scanning electron microscope.

DETAILED DESCRIPTION

[0070] Hereinafter, of the present disclosure will be described in more detail through specific examples. However, these examples are presented only as the illustrations of the present disclosure, and the scope of the right of the invention is not determined thereby.

PREPARATION EXAMPLE: PREPARATION OF SULFUR-CONTAINING ORGANIC PARTICLES A

[0071] Into a 250 mL round-bottom flask, 100 ml of triple distilled water was put, and degassed with argon (Ar) gas for 2 hours. And then, a 20 ml vial was closed with a septum and replaced with argon (Ar) gas, and oxygen (O.sub.2) gas included was removed by vacuum, which process was repeated three times. 2.401 g of sodium sulfide nonahydrate (Na.sub.2S.9H.sub.2O) and 961.98 mg of sulfur (S.sub.8) were introduced and 8 mL of degassed distilled water was added, and the reaction solution was heated to 30° C. and stirred for 12 hours. After the reaction was finished, 2 mL of degassed distilled water was added to prepare a polysulfide (Na.sub.2S.sub.4) aqueous solution. Wherein, the reaction formula of preparing the polysulfide (Na.sub.2S.sub.4) aqueous solution is as follows, and FIG. 1 is a photograph of the prepared polysulfide aqueous solution, taken by scanning electron microscope.

##STR00003##

[0072] And then, into a 20 mL vial, 85 mg of polyvinylpyrrolidone and 288 mg of sodium dodecyl sulfate (SDS) were introduced, and a process of replacing with argon gas and removing oxygen gas in the vial by vacuum was repeated three times. And then, 10 mL of degassed triple distilled water was added, and the reaction solution was heated to 30° C. and stirred for 12 hours. And, 0.05 mL of divinyl sulfone(DVS) from which an inhibitor had been removed was introduced into the vial, and the reaction solution was stirred for 10 minutes. And then, 0.45 mL of the polysulfide (Na.sub.2S.sub.4) aqueous solution was slowly added for 40 seconds using a liquid injector, and then, reacted for 30 minutes. After confirming that a turbid yellow solution turned into turbid white, hydrochloric acid was added to adjust the pH of the solution to 7. And then, a process of precipitating the product on triple distilled water using a centrifuge, and removing polyvinylpyrrolidone and sodium dodecyl sulfate was repeated 10 times, and by drying in a vacuum oven, sulfur-containing organic particles A were prepared.

[0073] Wherein, the reaction formula of preparing sulfur-containing organic particles is as shown in the following Reaction Formula 2, wherein n denotes the number of sulfur atoms included in the aqueous solution of a polysulfide compound, and the polysulfide compound comprises 4 sulfur atoms. Meanwhile, m denotes the number of repeat units included in the prepared sulfur-containing organic particles. And, it was confirmed through element analysis of the prepared sulfur-containing organic particles, that the content of sulfur atoms is 80 wt %. And, FIG. 2 is a photograph of the prepared sulfur-containing organic particles, taken by scanning electron microscope, confirming that the particle diameter of each prepared sulfur-containing organic particles is 200 nm.

##STR00004##

EXAMPLE 1

[0074] 1 g of the following episulfide compound 70A, 0.024 g of the sulfur-containing organic particles A prepared in the Preparation Example, 0.123 g of a reducing agent triphenylphosphine (PPh.sub.3), and 0.05 g of a dispersant cetyl trimethylammonium bromide (CTAB) were mixed, and then, the mixed solution was filtered using a glass filter having a pore size of 1 μm. And then, on each side of LCD Glass having a width of 10 cm and a height of 10 cm, slide glass having a thickness of 1 mm was placed, and about 5 g of the above mixed solution was applied on the center of the LCD Glass, and then, covered with another LCD Glass, thus preparing a mold. It was put in an oven, and a curing reaction was progressed at about 60° C. for about 10 hours, and at about 90° C. for about 4 hours. After taking out from the oven, the LCD glasses were removed to obtain a plastic specimen, which is a flat optical member. The thickness of the plastic specimen was about 1 mm, when measured using a thickness gauge (Model: ID-C112XBS) manufactured by Mitutoyo corporation.

##STR00005##

EXAMPLES 2 TO 5 AND COMPARATIVE EXAMPLE 1

[0075] Curable compositions and the cured products thereof, plastic specimens, were prepared by the same method as Example 1, except that the episulfide compounds, sulfur-containing organic particles A, reducing agents, dispersants and catalysts were used in the contents described in the following Table 1. Meanwhile, 70B used in Comparative Example 1 is as follows.

##STR00006##

TABLE-US-00001 TABLE 1 Sulfur-containing organic (unit: g) 70A 70B particles A PPh.sub.3 TCEP CTAB SDS DCA Example 1 1.000 — 0.024 0.123 — 0.050 — — Example 2 1.000 — 0.024 0.123 0.050 — 0.050 — Example 3 1.000 — 0.050 — 0.050 0.020 — 0.011 Example 4 1.000 — 0.100 — 0.050 0.020 — 0.021 Example 5 1.000 — 0.200 — 0.050 0.020 — 0.031 Comparative 0.900 0.100 — — — — — — Example 1 TCEP: reducing agent, tris(2-carboxyethyl)phosphine SDS: dispersant, Sodium Dodecyl Sulfate DCA: catalyst, Dicyclohexylamine

Property Evaluation

[0076] 1. Evaluation of Transmittance, Haze and Yellow Index

[0077] For each of the above specimens, based on 1mm standard thickness, in the thickness direction of the cured product, using NDH-5000 manufactured by Nippon Denshoku Industries Co. LTD, transmittance (JIS K 7361) and haze (JIS K 7136) were measured, and the results were shown in the following Table 2.

[0078] And, for each specimen, using a colorimeter, yellow index was measured, and the results were shown in the following Table 2.

2. Measurement of Glass Transition Temperature (Tg)

[0079] For each specimens, using differential scanning calorimeter (DSC) manufactured by TA Instrument Inc., glass transition temperature was measured, and the results were shown in the following Table 2.

3. Measurement of Refractive Index

[0080] For each specimen, using spectroscopic ellipsometry manufactured by Ellipso Technology Co. Ltd., a refractive index value was measured at the wavelength of 532 nm, and the results were shown in the following Table 2.

TABLE-US-00002 TABLE 2 Trans- Yellow Glass mittance index transition Refractive (%) haze (Y.I.) temperature (° C.) index Example 1 87.8 0.3 3.4 84 1.715 Example 2 87.5 0.7 3.7 80 1.710 Example 3 87.5 0.6 3.5 85 1.725 Example 4 87.5 0.6 3.6 85 1.750 Example 5 86.4 1.0 4.7 80 1.745 Comparative 88.0 0.3 3.4 74 1.705 Example 1

[0081] Referring to Table 2, it was confirmed that the specimens comprising the composition according to Examples of the present disclosure not only exhibit excellent optical properties, including high transmittance, and low haze and yellow index, but also exhibit very high glass transition temperature (Tg) of 85° C. or less, and high refractive indexes of 1.710 or more. Meanwhile, it was confirmed that in the case of

[0082] Comparative Example 1, both glass transition temperature and refractive index are low.