Isocyanate composition with improved stability and reactivity, and optical lens using same

Abstract

An embodiment relates to an isocyanate composition with improved stability and reactivity and a plastic optical lens using the same. The isocyanate composition has improved stability since the content of chlorine in the composition is adjusted to 22-500 ppm, and thus the isocyanate composition can prevent the deterioration in reactivity even in the long-term storage. Therefore, the isocyanate composition according to an example, even when used after long-term storage after preparation, can be prepared, through polymerization with a thiol-based compound, as a polythiourethane-based optical material with excellent physical properties, such as refractive index, Abbe number, transparency, glass transition temperature, and yellowness, and thus the isocyanate composition is useful in fields of glass lenses, a camera lens, and the like.

Claims

1. An isocyanate composition, which comprises a chlorine-based storage stabilizer and hydrogenated xylylene diisocyanate (H.sub.6XDI), wherein the amount of H.sub.6XDI in the isocyanate composition is 90% by weight or more, wherein the content of chlorine in the entire composition is 22 to 500 ppm, wherein the chlorine-based storage stabilizer comprises at least one selected from the group consisting of a chlorine ion, benzotrichloride, benzyl chloride, benzoyl chloride, and a C.sub.1-10 alkanoyl chloride, and wherein the content of the NCO groups contained in the entire composition is 42 to 45% by weight, wherein when the isocyanate composition is left at a temperature of 80° C. for 6 months, the amount of precipitates generated is 1% by weight or less based on the total weight of the composition, and wherein the difference in the content of the NCO groups between the initial composition and the composition left at a temperature of 80° C. for 6 months is 5% by weight or less.

2. The isocyanate composition of claim 1, wherein the chlorine-based storage stabilizer comprises a chlorine ion.

3. The isocyanate composition of claim 1, wherein the chlorine-based storage stabilizer is selected from the group consisting of benzotrichloride, benzyl chloride, benzoyl chloride, and a C.sub.1-10 alkanoyl chloride.

4. The isocyanate composition of claim 1, wherein when the isocyanate composition is sealed and left in a container, the region of which in contact with the composition is not reactive with chlorine, at a temperature of 80° C. for 6 months, the difference in the content of the NCO groups between the initial composition and the composition after 6 months is 4% by weight or less.

5. An isocyanate composition, which comprises a chlorine-based storage stabilizer and hydrogenated xylylene diisocyanate (H.sub.6XDI), wherein the amount of H.sub.6XDI in the isocyanate composition is 90% by weight or more, wherein the content of the NCO groups contained in the entire composition is 42 to 45% by weight; wherein the chlorine-based storage stabilizer comprises at least one selected from the group consisting of a chlorine ion, benzotrichloride, benzyl chloride, benzoyl chloride, and a C.sub.1-10 alkanoyl chloride, and wherein when the isocyanate composition is left at a temperature of 80° C. for 6 months, the amount of precipitates generated is 1% by weight or less based on the total weight of the composition, and wherein the difference in the content of the NCO groups between the initial composition and the composition left at a temperature of 80° C. for 6 months is 5% by weight or less.

6. A process for preparing an isocyanate composition, which comprises (1) producing a composition that comprises hydrogenated xylylene diisocyanate (H.sub.6XDI) from cyclohexyldi(methylamine) by a process for synthesizing an isocyanate; and (2) adjusting the content of chlorine contained in the composition that comprises hydrogenated xylylene diisocyanate to 22 to 500 ppm, wherein when the isocyanate composition is sealed and left at a temperature of 80° C. for 6 months, the amount of precipitates generated is 1% by weight or less based on a total weight of the composition, and a difference in the content of the NCO groups between the initial composition and the composition left at a temperature of 80° C. for 6 months is 5% by weight or less, wherein the amount of H.sub.6XDI in the isocyanate composition is 90% by weight or more, wherein the isocyanate composition comprises a chlorine-based storage stabilizer, wherein the chlorine-based storage stabilizer comprises at least one selected from the group consisting of a chlorine ion, benzotrichloride, benzyl chloride, benzoyl chloride, and a C.sub.1-10 alkanoyl chloride.

7. The process for preparing an isocyanate composition of claim 6, wherein the step (2) is carried out by adding to the composition that comprises H.sub.6XDI at least one chlorine-based storage stabilizer selected from the group consisting of benzotrichloride, benzyl chloride, benzoyl chloride, and a C.sub.1-10 alkanoyl chloride, or containing a chlorine ion.

8. The process for preparing an isocyanate composition of claim 6, wherein the step (2) further comprises subjecting the composition that comprises H.sub.6XDI to heat distillation.

9. A polymerizable composition, which comprises an isocyanate composition and a thiol-based compound, wherein the isocyanate composition comprises a chlorine-based storage stabilizer and hydrogenated xylylene diisocyanate (H.sub.6XDI), wherein the amount of H.sub.6XDI in the isocyanate composition is 90% by weight or more, wherein the content of chlorine in the isocyanate composition is 22 to 500 ppm, wherein the chlorine-based storage stabilizer comprises at least one selected from the group consisting of a chlorine ion, benzotrichloride, benzyl chloride, benzoyl chloride, and a C.sub.1-10 alkanoyl chloride, and wherein the content of the NCO groups contained in the isocyanate composition is 42 to 45% by weight, wherein when the isocyanate composition is left at a temperature of 80° C. for 6 months, the amount of precipitates generated is 1% by weight or less based on the total weight of the composition, and wherein the difference in the content of the NCO groups between the initial composition and the composition left at a temperature of 80° C. for 6 months is 5% by weight or less.

10. An optical lens, which comprises a polythiourethane formed by curing a polymerizable composition that comprises an isocyanate composition and a thiol-based compound, wherein the isocyanate composition comprises a chlorine-based storage stabilizer and hydrogenated xylylene diisocyanate (H.sub.6XDI), wherein the amount of H.sub.6XDI in the isocyanate composition is 90% by weight or more, wherein the content of chlorine in the isocyanate composition is 22 to 500 ppm, wherein the chlorine-based storage stabilizer comprises at least one selected from the group consisting of a chlorine ion, benzotrichloride, benzyl chloride, benzoyl chloride, and a C.sub.1-10 alkanoyl chloride, wherein the content of the NCO groups contained in the isocyanate composition is 42 to 45% by weight, wherein when the isocyanate composition is left at a temperature of 80° C. for 6 months, the amount of precipitates generated is 1% by weight or less based on the total weight of the composition, and wherein the difference in the content of the NCO groups between the initial composition and the composition left at a temperature of 80° C. for 6 months is 5% by weight or less.

11. The optical lens of claim 10, which has a yellow index (YI) of 1 to 20 and a light transmittance of 85.0 to 99.9% at a wavelength of 550 nm.

12. The optical lens of claim 10, which has an Abbe number of 30 to 45 and a glass transition temperature of 75 to 120° C.

13. A process for producing an optical lens, which comprises: (A) providing an isocyanate composition, (B) providing a thiol-based compound, (C) providing a polymerizable composition that comprises the isocyanate composition and the thiol-based compound, and (D) curing the polymerizable composition, wherein the isocyanate composition comprises a chlorine-based storage stabilizer and hydrogenated xylylene diisocyanate (H.sub.6XDI), wherein the amount of H.sub.6XDI in the isocyanate composition is 90% by weight or more, wherein the content of chlorine in the isocyanate composition is 22 to 500 ppm, wherein the chlorine-based storage stabilizer comprises at least one selected from the group consisting of a chlorine ion, benzotrichloride, benzyl chloride, benzoyl chloride, and a C.sub.1-10 alkanoyl chloride, and wherein the content of the NCO groups contained in the isocyanate composition is 42 to 45% by weight, wherein when the isocyanate composition is left at a temperature of 80° C. for 6 months, the amount of precipitates generated is 1% by weight or less based on the total weight of the composition, and wherein the difference in the content of the NCO groups between the initial composition and the composition left at a temperature of 80° C. for 6 months is 5% by weight or less.

Description

EXAMPLE

(1) Examples 1: Preparation of an Isocyanate Composition

(2) (1) Preparation of Raw Materials

(3) 5 parts by weight of (3-(aminomethyl)cyclohexyl)methanamine was dissolved in 78 parts by weight of o-dichlorobenzene to prepare an amine solution. Thereafter, 44 parts by weight of phosgene was dissolved in 52 parts by weight of o-dichlorobenzene to prepare a solution, which was cooled to 10° C. with a brine condenser and then placed in a reaction vessel. The amine solution prepared above was slowly added thereto at a temperature of 50° C. or lower. In such event, the amount of the amine solution added was adjusted such that 5 moles of phosgene was added per 1 mole of amine. Thereafter, the reaction vessel was sealed, and the reaction solution was stirred for 2 hours. After further reaction for 3 hours at a temperature of 140° C. and a pressure of 3 kg/cm.sup.2, the hydrochloric acid gas produced during the reaction was discharged. Upon completion of the reaction, the excessive phosgene was removed by a distillation process. The product was purified by fractional distillation under a reduced pressure to produce a composition comprising H.sub.6XDI.

(4) (2) Adjustment of Chlorine Content

(5) A chlorine-based storage stabilizer was added to the composition comprising H.sub.6XDI obtained above as shown in the following Table 1 to prepare isocyanate compositions 1 to 7 having various chlorine contents.

(6) Specifically, the step of adding a chlorine ion was carried out by injecting chlorine gas while the composition comprising H.sub.6XDI was stirred at room temperature for 1 hour to dissolve it, and then the undissolved chlorine gas was removed under a reduced pressure for about 30 minutes. In addition, the step of adding a chlorine-based storage stabilizer was carried out by adding each of the chlorine-based storage stabilizers listed in Table 1 below, followed by sufficient stirring at 35° C. for about 1 hour.

(7) Thereafter, if excessive chlorine was present in the composition as measured by combustion ion chromatography, the composition was subjected to distillation at 80° C. to remove the chlorine ion and/or chlorine-based compound. Then, the chlorine content was measured again; and, if necessary, the above steps were repeated.

(8) Example 2: Production of an Optical Lens

(9) Isocyanate compositions were prepared in the same manner as in Example 1, except that the chlorine-based storage stabilizer was used as described in Evaluation Example 1 below.

(10) Specifically, 520 g of the isocyanate composition, 479.3 g of 3,3′-thiobis[2-[(2-mercaptoethyl)thio]-1-propanethiol], 0.15 g of dibutyl tin dichloride as a curing catalyst, and 0.80 g of Zelec™ UN as an internal mold release agent were mixed uniformly to prepare a polymerizable composition. Then, the polymerizable composition was mixed at a reduced pressure in a nitrogen atmosphere for 30 minutes to remove bubbles and then filtered through a Teflon filter of 3 μm. The filtered polymerizable composition was injected into a glass mold assembled with an adhesive tape using nitrogen pressure. The glass mold injected with the polymerizable composition was placed in a forced circulation oven, and the temperature was elevated from 25° C. to 120° C. at a rate of 5° C./min, followed by polymerization at 120° C. for 18 hours. Thereafter, the polymerized resin was further cured at 130° C. for 4 hours, and a lens was released from the glass mold to obtain each optical lens having a center thickness of 1.2 mm.

Evaluation Example

(11) Evaluation Examples 1: Evaluation of an Isocyanate Composition

(12) The isocyanate composition prepared in Example 1 was evaluated for the storage stability in accordance with the method as described below. The results are shown in Table 1 to 3 below.

(13) (1) Evaluation of Storage Stability of Isocyanate Compositions with Respect to the Chlorine Content

(14) The initial NCO content (NCO %) of the isocyanate compositions 1 to 7 whose chlorine content had been adjusted in Example 1 was measured by a back-titration method. First, an excess of n-butylamine relative to the theoretical NCO content was added and reacted, and the excessive n-butylamine that remained was analyzed with a 0.1 N hydrochloric acid reagent. The results are shown in Table 1 below.

(15) In addition, Table 1 also summarizes the initial color of the isocyanate compositions, whether cloudiness occurred, and whether precipitates were present. The cloudiness and precipitates were determined by placing the isocyanate composition in a clear glass bottle, filling the bottle with nitrogen, and sealing it, which was then allowed to stand for one day or longer, and the appearance and the presence of precipitated materials on the bottom were observed. In such event, if the glass bottle containing the composition was transparent or no precipitate was generated, it was evaluated to be X. If it was cloudy or a precipitate was generated, it was evaluated to be º. In addition, if the amount of precipitates generated was 1% or less based on the total weight of the composition, it was evaluated to be X. If it exceeded 1%, it was evaluated to be º.

(16) Thereafter, the isocyanate compositions 1 to 7 were stored at a temperature of 80° C. for 6 months. The NCO % of the isocyanate compositions 1 to 7 was measured in accordance with the method described above. The color, whether cloudiness occurred, and whether precipitates were present were evaluated. The method and criteria of evaluation are as described above. The results are shown in Table 1 below.

(17) TABLE-US-00001 TABLE 1 Chlorine-based Isocyanate storage Chlorine Initial After 6 months (@80° C.) Composition stabilizer (ppm) NCO % Color C* P* NCO % Color C* P* Composition 1 Benzoyl chloride 20 43.3 Transparent X X 40.3 Transparent ◯ ◯ Composition 2 Chlorine ion 50 43.3 Transparent X X 43.3 Transparent X X Composition 3 Benzoyl chloride 200 43.3 Transparent X X 43.3 Transparent X X Composition 4 Chlorine 370 43.3 Transparent X X 43.3 Transparent X X ion + Benzoyl chloride Composition 5 Chlorine 500 43.3 Transparent X X 43.3 Transparent X X ion + Benzoyl chloride Composition 6 Chlorine 610 43.3 Transparent X X 43.3 Yellowing X X ion + Benzoyl chloride Composition 7 Benzoyl chloride 800 43.3 Transparent X X 43.3 Yellowing X X *C: cloudiness; P: precipitate

(18) As confirmed from Table 1 above, the isocyanate compositions (compositions 2 to 5) having a chlorine content within 22 to 500 ppm retained a transparent color with almost no changes in the NCO % after storage for 6 months and without any cloudiness and precipitates. Thus, their stability was excellent even when they were stored for a long period of time.

(19) In contrast, the other isocyanate compositions having a chlorine content of less than 22 ppm or more than 500 ppm changed to yellow or had cloudiness or precipitates after storage for 6 months, indicating decreased stability when they were stored for a long period of time.

(20) (2) Evaluation of Storage Stability of Isocyanate Compositions with Respect to the Container

(21) The initial metal concentration of the isocyanate compositions 1 to 7 whose chlorine content had been adjusted in Example was measured. Then, they were each stored at 80° C. for 6 months in a container made of different materials, and the concentration of the residual metal ions was measured.

(22) Table 2 shows analysis results of the samples stored in stainless steel (SUS 304) containers, and Table 2 shows those of the samples stored in steel containers whose interior had been coated with polyethylene.

(23) TABLE-US-00002 TABLE 2 Stored in stainless steel containers Isocyanate Chlorine Initial (ppm) After 6 months (@80° C.) Composition (ppm) Cr Fe Mn Ni Cr Fe Mn Ni Composition 1 20 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Composition 2 50 <0.1 <0.1 <0.1 <0.1 <0.1 0.4 <0.1 <0.1 Composition 3 200 <0.1 <0.1 <0.1 <0.1 <0.1 0.8 <0.1 <0.1 Composition 4 370 <0.1 <0.1 <0.1 <0.1 <0.1 3.2 <0.1 4.3 Composition 5 500 <0.1 <0.1 <0.1 <0.1 0.5 13 5.5 6.0 Composition 6 610 <0.1 <0.1 <0.1 <0.1 1.8 35 20 39 Composition 7 800 <0.1 <0.1 <0.1 <0.1 3.6 99 85 67

(24) TABLE-US-00003 TABLE 3 Stored in steel containers whose interior had been coated with polyethylene Isocyanate Chlorine Initial (ppm) After 6 months (@80° C.) Composition (ppm) Cr Fe Mg Ni Cr Fe Mg Ni Composition 1 20 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Composition 2 50 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Composition 3 200 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Composition 4 370 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Composition 5 500 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Composition 6 610 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Composition 7 800 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

(25) As shown in Tables 2 and 3, when the isocyanate composition was stored in a stainless steel container, the amount of metal eluted was greatly increased as the chlorine content in the composition was increased. In contrast, when it was stored in a steel container coated with polyethylene, a very small amount of metal was eluted even when the chlorine content in the composition was increased.

(26) Evaluation Example 2: Evaluation of Optical Lenses

(27) The optical lenses produced in Example 2 were evaluated for the physical properties according to the following methods. The results are shown in Table 4 below.

(28) (1) Refractive Index and Abbe Number

(29) The refractive index and Abbe number of the optical lens was measured at 20° C. using an Abbe refractometer DR-M4 (Atago Co.).

(30) (2) Yellow Index and Light Transmittance

(31) The optical lenses were each measured for chromaticity coordinates x and y using a spectrophotometer CT-210 manufactured by Minolta Co., from which their yellow indices were calculated with Equation 1 below. In addition, the transmittance at a wavelength of 550 nm was measured from the spectrum obtained using the same instrument.
Y.I=(234x+106y+106)/y   [Equation 1]

(32) (3) Glass Transition Temperature (Tg, ° C.)

(33) The glass transition temperature of the optical lens was measured with TMA Q400 (TA instruments Co.) under the penetration method (load of 50 g, pin line of 0.5 mm Φ, temperature elevation rate of 10° C./min)

(34) (4) Stria

(35) 100 optical lenses were each observed with the naked eyes under a mercury lamp. The lenses with non-uniformity were determined to have stria, and the percentages were calculated. As a result, if the generation of stria was less than 5%, it was evaluated to be good. If it was 5% or more, it was evaluated to be poor.

(36) TABLE-US-00004 TABLE 4 Light Yellow Isocyanate Chlorine Refractive Abbe number transmittance Tg index Composition (ppm) index (nd) (ve) (%) (° C.) (Y.I.) Stria Composition 1 20 Not Not measurable 65 75 10 Poor measurable Composition 2 50 1.6322 37 87 90 12 Good Composition 3 200 1.6331 38 87 91 12 Good Composition 4 370 1.6333 38 89 88 11 Good Composition 5 500 1.6312 39 88 90 10 Good Composition 6 610 1.6321 36 80 90 25 Poor Composition 7 800 1.6322 35 70 89 46 Poor

(37) As confirmed from Table 4 above, when the isocyanate compositions (compositions 2 to 5) having a chlorine content of 22 to 500 ppm were used to produce lenses after storage for 6 months, the lenses produced therefrom were excellent in all of the refractive index, Abbe number, transmittance, Tg, and yellow index. In contrast, when the isocyanate compositions(compositions 1, 6, and 7) having a chlorine content of less than 22 ppm or greater than 500 ppm were used to produce lenses after storage for 6 months, the lenses produced therefrom were poor at least one of the refractive index, Abbe number, transmittance, Tg, yellow index, and stria.

(38) This attributes to the fact that the chlorine content significantly affects the reactivity of H.sub.6XDI. Specifically, if the chlorine content in the isocyanate composition is less than 22 ppm, the storage stability of the composition is deteriorated due to the excessive reactivity of H.sub.6XDI, and the reaction becomes too rapid when it is used to produce a lens, resulting in nonuniform optical characteristics thereof. If the chlorine content exceeds 500 ppm, it is expected that the reactivity suppression effect of H.sub.6XDI is excessive, so that the reaction and/or curing in the production of a lens would not take place, which lowers the optical characteristics thereof.