CURABLE COMPOSITION AND OPTICAL MATERIAL COMPRISING CURED PRODUCT THEREOF

Abstract

A curable composition for forming a high refractive index optical material including an episulfide compound, a cyclic disulfide compound, and a reducing agent, and an optical material comprising a cured product of the curable composition.

Claims

1. A curable composition for forming a high refractive index optical material comprising: an episulfide compound; a cyclic disulfide compound containing one or more repeating units represented by the following Chemical Formula 1; and a reducing agent, Chemical Formula 1 ##STR00010## wherein in the Chemical Formula 1, Ar1 is a heteroarylene having 2 to 30 carbon atoms and containing at least one of nitrogen (N) and sulfur (S) atoms, and n is an integer of 1 to 5.

2. The curable composition according to claim 1, wherein the cyclic disulfide compound comprises a compound represented by the following Chemical Formula 2 or 3, Chemical Formula 2 ##STR00011## wherein in the Chemical Formula 2, Ar2 to Ar4 are each independently a heteroarylene having 2 to 30 carbon atoms and containing at least one of nitrogen (N) and sulfur (S) atoms, Chemical Formula 3 ##STR00012## wherein in the Chemical Formula 3, Ar5 to Ar8 are each independently a heteroarylene having 2 to 30 carbon atoms and containing at least one of nitrogen (N) and sulfur (S) atoms.

3. The curable composition according to claim 1, wherein the episulfide compound comprises a compound represented by the following Chemical Formula 4. Chemical Formula 4 ##STR00013## wherein in the Chemical Formula 4, R.sub.1 and R.sub.2 are each independently hydrogen or an alkyl having 1 to 10 carbon atoms, R.sub.3 and R.sub.4 are each independently a single bond or an alkylene having 1 to 10 carbon atoms, a is an integer of 0 to 4, and b is an integer of 0 to 6.

4. The curable composition according to claim 1, wherein the cyclic disulfide compound comprises at least one selected from the group consisting of the following: ##STR00014##

5. 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.

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

7. The curable composition according to claim 1, wherein the curable composition further comprises a thiol compound represented by the following Chemical Formula 5. Chemical Formula 5 ##STR00015## wherein in the Chemical Formula 5, R.sub.5 and R.sub.6 are each independently a single bond or an alkylene having 1 to 10 carbon atoms, c is an integer of 0 to 4, and d is an integer of 0 to 6.

8. The curable composition according to claim 7, wherein the thiol compound comprises at least one selected from the group consisting of the ##STR00016##

9. The curable composition according to claim 1, wherein a weight ratio between the episulfide compound and the cyclic disulfide compound is 7:3 to 9:1.

10. The curable composition according to claim 1, wherein a weight ratio between the reducing agent and the cyclic disulfide compound is 1:10 to 1:500.

11. The curable composition according to claim 1, wherein the curable composition further comprises a catalyst.

12. An optical material including a cured product of a composition, the composition comprises: an episulfide compound; a cyclic disulfide compound containing at least one repeating unit of the following Chemical Formula 1; and a reducing agent, Chemical Formula 1 ##STR00017## wherein in the Chemical Formula 1, Ar.sub.1 is a heteroarylene having 2 to 30 carbon atoms and containing at least one of nitrogen (N) and sulfur (S) atoms, and n is an integer of 1 to 5.

13. The optical material according to claim 12, wherein the composition further comprises a thiol compound represented by the following Chemical Formula 5. Chemical Formula 5 ##STR00018## wherein in the Chemical Formula 5, R.sub.5 and R.sub.6 are each independently a single bond or an alkylene having 1 to 10 carbon atoms, c is an integer of 0 to 4, and d is an integer of 0 to 6.

14. The optical material according to claim 12, wherein the optical material has a refractive index of 1.65 or more.

15. The optical material according to claim 12, wherein the optical material has a transmittance of 80% or more.

16. The optical material according to claim 12, wherein the optical material has a haze of 1.2% or less.

17. The optical material according to claim 12, wherein the optical material is for a lens of a wearable device.

18. The curable composition according to claim 1, wherein the curable composition further comprises a thiol compound comprising at least one selected from the group consisting of the following: ##STR00019##

Description

DETAILED DESCRIPTION

[0094] Hereinafter, the actions and effects of the invention will be described in more detail through specific examples of the invention. However, these examples are for illustrative purposes only, and the scope of rights of the invention is not determined thereby.

Example 1

[0095] 87 g of the following 70A as an episulfide compound, 13 g of the following cyclic disulfide compound, and 0.1 g of 1,4-dimercaptobutane-2,3-diol (DTT) as a reducing agent were vigorously mixed at 10° C. for 2 hours, and then the mixture was filtered using a glass filter having a pore size of 1 μm. Then, 0.5 g of N,N-dicyclohexylmethylamine was added as a catalyst and mixed for 5 minutes to prepare a curable composition.

[0096] A 1 mm thick slide glass was placed on both sides of a LCD glass having a size of 10 cm in width and length, and about 5 g of the above-mentioned mixed solution was applied to the center of the LCD glass, and then covered with another LCD glass to prepare a mold. This was put in an oven, and the curing reaction was performed at about 60° C. for about 10 hours and at about 90° C. for about 4 hours. After taken out of the oven, the LCD glass was removed to obtain a flat plastic specimen (optical material). The thickness of the plastic specimen was about 1 mm, and this thickness was measured using a Mitutoyo thickness gauge (Model: ID-C112XBS).

Examples 2 to 8 and Comparative Examples 1 to 2

[0097] A curable composition and a plastic specimen (optical material) as a cured product thereof were prepared in the same manner as in Example 1, except that the episulfide compound, the cyclic disulfide compound, and the reducing agent were used in the amount of the compounds shown in Table 1 below, and the mixing temperature was controlled to the temperature listed in Table 1 below.

[0098] On the other hand, in Examples 5 to 8 and Comparative Example 2, the following 70B as a thiol compound was further used at the content shown in Table 1 below.

##STR00009##

TABLE-US-00001 TABLE 1 Mixing Cyclic temperature (unit: g) 70A 70B disulfide Catalyst DTT (° C.) Example 1 87 — 13 0.5 0.1 10 Example 2 87 — 13 0.5 0.3 10 Example 3 87 — 13 0.5 0.3 25 Example 4 87 — 13 0.5 0.5 10 Example 5 87 3 10 0.5 0.3 10 Example 6 87 3 10 0.5 0.5 10 Example 7 87 3 10 0.5 0.5 25 Example 8 87 3 10 0.5 0.7 10 Comparative 87 — 13 0.5 — 10 Example 1 Comparative 87 3 10 0.5 — 10 Example 2

[0099] Evaluation of Physical Properties

[0100] 1. Evaluation of Transmittance, Haze and Yellowness Index

[0101] The transmittance (JIS K 7361) and haze (JIS K 7136) of the specimen were measured in the thickness direction of the cured product cured to a 1 mm standard thickness using NDH-5000 manufactured by Nippon Denshoku Industries Co., LTD., and the results are shown in Table 2 below.

[0102] In addition, the yellowness index of the specimen was measured using a colorimeter, and the results are shown in Table 2 below.

[0103] 2. Measurement of Sulfur Atom Content

[0104] The content of sulfur atoms in the specimen was measured using an elemental analysis method, and the results are shown in Table 2 below.

[0105] 3. Measurement of Refractive Index

[0106] For the specimen, the refractive index value at a wavelength of 532 nm was measured using spectroscopic ellipsometry manufactured by Ellipso Technology, and the results are shown in Table 2 below.

[0107] 4. Measurement of Glass Transition Temperature (Tg)

[0108] The glass transition temperature of the specimen was measured using a differential scanning calorimeter (DSC) manufactured by TA Instrument, and the results are shown in Table 2 below.

TABLE-US-00002 TABLE 2 Sulfur Glass atom transition Transmittance Yellowness content Refractive temperature Haze (%) (%) index (wt. %) index (° C.) Example 1 1.19 87.1 4.92 54.85 1.74 85.0 Example 2 0.97 87.3 4.78 54.82 1.74 84.3 Example 3 0.62 87.3 4.41 54.82 1.74 84.4 Example 4 0.71 87.3 4.54 54.78 1.74 83.3 Example 5 1.12 87.0 4.43 54.82 1.74 73.4 Example 6 1.09 87.1 4.11 54.75 1.74 73.2 Example 7 0.62 87.1 3.90 54.75 1.74 73.2 Example 8 1.00 87.1 4.10 54.59 1.74 73.1 Comparative Example 1 1.56 86.6 5.23 54.87 1.74 85.4 Comparative Example 2 1.27 86.3 4.32 54.82 1.74 73.7

[0109] Referring to Table 2, it was confirmed that the specimen including the cured product according to Examples of the present disclosure had a very low haze of 1.2% or less. In particular, in Examples 3 and 7, the mixing temperature of the composition was controlled to 25° C., and in particular, the temperature of the reduction reaction of cyclic disulfide through a reducing agent was controlled to 25° C., and the haze was as very low as 0.62%.

[0110] On the other hand, in the case of Comparative Examples 1 and 2, it was confirmed that the haze was too high and the optical properties were low compared to Examples of the present disclosure.

[0111] In addition, in Examples 1 to 8, it was confirmed that the transmittance was as high as 87.0% or more, and the yellowness index as low as 4.92 or less, and thus, the optical properties were excellent, and that the refractive index was 1.74, which had a high refractive index similar to glass, and thus could be used as an optical material instead of glass. Further, it was confirmed that the glass transition temperature was 73.1° C. or more, and the heat resistance of the optical material as a cured product was excellent.

[0112] However, in the case of Comparative Examples 1 and 2, it was confirmed that the refractive index and the glass transition temperature were similar to those of Examples, but the optical properties of the transmittance were not good. In addition, it was confirmed that Comparative Example 1 exhibited substantially high values for both haze and yellowness index, since Comparative Example 1 did not contain a reducing agent even though it contained a large amount of cyclic disulfide compound.