Preparation method for polyurethane optical resin and applications thereof

Abstract

Preparation method for a polyurethane optical resin and applications thereof. The preparation method for the polyurethane optical resin comprises: a raw material composition comprising isocyanate and a polythiol compound undergoes a polymerization to produce the polyurethane optical resin. The turbidity value of the isocyanate used in the raw material composition is controlled at ?2 NTU. The polyurethane optical resin produced is applicable in manufacturing optical products.

Claims

1. A quality control method of a polyurethane optical resin, wherein the polyurethane optical resin is prepared by subjecting a raw material composition containing an isocyanate and a polythiol compound to a polymerization reaction to obtain the polyurethane optical resin, the isocyanate is selected from the group consisting of an aliphatic and an aromatic isocyanate; the polythiol compound is 1,2-bis[(2-mercaptoethyl)thio]-3-mercaptopropane; the quality control method comprises controlling exposed placement conditions of the isocyanate as: an ambient relative humidity of the aromatic isocyanate after opening packaging barrel thereof before use to be less than or equal to 35% for less than or equal to 48 h, and an ambient relative humidity of the aliphatic after opening packaging barrel thereof before use to be less than or equal to 35% for less than or equal to 240 h; the turbidity of the isocyanate in the raw material composition is controlled to be less than or equal to 2 NTU.

2. The method according to claim 1, wherein the preparation method of the polyurethane optical resin comprises stirring and mixing components in the raw material composition and then degassing and curing the mixture to obtain the polyurethane optical resin; wherein a ratio in amount of the isocyanate to the polythiol compound is based on a molar ratio of an NCO group to an SH group, which is controlled to be (0.8-1.3):1, preferably (0.9-1.2):1.

3. The method according to claim 1, wherein the aliphatic isocyanate is selected from the group consisting of hexamethylene diisocyanate, methylcyclohexyl diisocyanate, dimethylcyclohexyl diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, norbornane diisocyanate and cyclohexyl dimethylene diisocyanate.

4. The method according to claim 1, wherein the aromatic isocyanate is selected from the group consisting of toluene diisocyanate, p-phenylene diisocyanate and xylylene diisocyanate.

5. The method according to claim 1, wherein the isocyanate raw material is selected from the group consisting of cyclohexyl dimethylene diisocyanate and xylylene diisocyanate.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows the appearance of a cured piece of Example 1.

(2) FIG. 2 shows the appearance (left image) of a defective product among cured pieces in Example 4 and the appearance (right image) of a cured piece in Comparative Example 3.

DETAILED DESCRIPTION

(3) For a detailed understanding of technical features and contents of the present disclosure, preferred embodiments of the present disclosure are described in more detail below. Although the preferred embodiments of the present disclosure are described through examples, it is to be understood that the present disclosure may be implemented in various manners and should not be limited to the embodiments set forth herein.

(4) Unless otherwise specified, turbidity herein refers to the turbidity of an isocyanate.

(5) The following examples and comparative examples of the present disclosure are analyzed by the following instruments:

(6) A HACH2100N turbidimeter used in a turbidity test is produced by HACH in the United States and has a measurement range of 0-10000 NTU and a division value of 0.01 NTU. The scattering manner of the HACH2100N turbidimeter includes 90? scattering, forward scattering, backward scattering and transmission. The measurement range may be automatically selected, a tungsten lamp is used as a light source, and light with a wavelength of 400-600 nm is used.

(7) The product is evaluated by the following methods:

(8) The turbidity of a sample is determined as follows:

(9) an instrument is turned on and warmed up for 30 min;

(10) the sample is transferred to a dry and clean sample bottle and a bottle stopper is tightened, and bubbles are avoided when the sample is poured; the outer wall of the sample bottle is wiped with a microfiber dust-free cloth, and silicone oil with a proper amount is applied depending on scratches on the outer wall and wiped evenly; a minimum range that can be set is used during determination, the sample is put into a sample groove, and an orientation mark on the sample bottle is aligned with an orientation mark protruding from the front of a container chamber; and after a measured value is stable, a result is read.
Standard Calibration:

(11) According to a sample test method, a calibration curve is drawn using a turbidity standard solution in a calibration mode.

(12) An analysis result is reported to a second decimal place in NTUs.

(13) Temperature and humidity conditions under which the sample is placed are controlled with a constant temperature and humidity box GT-7005-A2M from Gotech Testing Machines (Dongguan) Co., Ltd.

(14) The yellowness index and transmittance of a solid polymer are tested with a HunterLab USVIS 1839 color difference meter. A fixed mold is used for preparing samples in the test.

(15) Qualification ratio: In this example, 100 pieces are visually observed under a high-pressure mercury lamp, and products with phenomena that local refractive index is different from the surrounding normal refractive index due to different composition, such as ripples and bubbles, are determined to be unqualified and counted to calculate the qualification ratio.

(16) Raw materials, metaxylylene diisocyanate (XDI) and cyclohexyl dimethylene diisocyanate (H.sub.6XDI), are used in the following examples, and the turbidity of the isocyanate is analyzed with a turbidimeter.

(17) The isocyanate raw materials used in the following examples and comparative examples are subjected to GC chromatography and moisture analysis, to obtain that the content of water is less than 100 ppm, the GC purity is greater than 99.51% (A/A), the content of chlorinated impurities is less than 0.025% (A/A), and the content of cyano impurities is less than 0.015% (A/A). A polythiol compound adopts the commercially available raw material, where a main content is 91.0%-95.0% (A/A), the rest is a mixture containing mercapto groups, and the content of water is less than 500 ppm. The raw materials used in the examples and comparative examples exclude the effect of known related impurities and moisture on the quality of an optical resin.

(18) In examples and comparative examples, 1 part by mass is 30 g.

Example 1

(19) 50 parts by mass of metaxylylene diisocyanate (XDI, 99.79% purity) with a turbidity of 0.242 NTU were added into a reaction kettle with a stirrer, and 0.015 parts by mass of dibutyltin dichloride as a catalyst, 0.10 parts by mass of acidic phosphate ester (Stepan, Zelec UN) and 0.05 parts by mass of an ultraviolet absorber (Rianlon, RIASORB UV531) were added at 25? C., mixed and dissolved. Then, 50 parts by mass of a polythiol compound, 1,2-bis[(2-mercaptoethyl)thio]-3-mercaptopropane (Jingbo Chemical, polythiol 501) were added based on a molar ratio of 1.08 of an NCO group to an SH group and mixed for 1 h at room temperature and at a rotational speed of 100 rpm to form a polymerizable raw material composition. After cooled to 20? C., the polymerizable raw material composition was degassed for 1.5 h at 2 kPa (absolute pressure) and 25? C., injected into a lens mold, heated from 20? C. to 120? C. for 24 h in an oven so that the raw material composition was polymerized and cured. Secondary curing was performed at 120? C. for 2 h after demolding to obtain an optical material. 100 pieces were prepared in the same batch and a proportion of qualified products was counted. Test results are shown in Table 1. The appearance of the obtained optical material piece after curing is shown in FIG. 1.

Example 2

(20) The isocyanate raw material used in this example was basically the same as that in Example 1 except that 51 parts by mass of XDI with a turbidity of 0.35 NTU and 49 parts by mass of 1,2-bis[(2-mercaptoethyl)thio]-3-mercaptopropane were added based on a molar ratio of 1.13 of the NCO group to the SH group. In addition, the polymerizable raw material composition was synthesized and plastic lens were manufactured in the same manner as in Example 1. The results are shown in Table 1.

Example 3

(21) The isocyanate raw material used in this example was basically the same as that in Example 1 except that 47 parts by mass of XDI with a turbidity of 0.55 NTU and 53 parts by mass of 1,2-bis[(2-mercaptoethyl)thio]-3-mercaptopropane were added based on a molar ratio of 0.96 of the NCO group to the SH group. In addition, the same operations were performed in this example as in Example 1. The results are shown in Table 1.

Example 4

(22) The isocyanate raw material used in this example was basically the same as that in Example 1 except that 52 parts by mass of XDI with a turbidity of 1.93 NTU and 48 parts by mass of 1,2-bis[(2-mercaptoethyl)thio]-3-mercaptopropane were added based on a molar ratio of 1.17 of the NCO group to the SH group. In addition, the same operations were performed in this example as in Example 1. The results are shown in Table 1. The appearance of a defective product among the optical material pieces obtained after curing is shown in the left image in FIG. 2.

Comparative Example 1

(23) The isocyanate raw material used was basically the same as that in Example 1 except that the isocyanate had a different turbidity. In this example, XDI with a turbidity of 8.12 NTU was used. In addition, the same operations were performed in this comparative example as in Example 1. The results are shown in Table 1.

Comparative Example 2

(24) The isocyanate raw material used was basically the same as that in Example 1 except that the isocyanate had a different turbidity. In this example, XDI with a turbidity of 30.23 NTU was used. In addition, the same operations were performed in this comparative example as in Example 1. The results are shown in Table 1.

Comparative Example 3

(25) The isocyanate raw material used was basically the same as that in Example 1 except that the isocyanate had a different turbidity. In this example, XDI with a turbidity of 2330 NTU was used. In addition, the same operations were performed in this comparative example as in Example 1. The results are shown in Table 1. The appearance of a defective product among the optical material pieces obtained after curing is shown in the right image in FIG. 2.

Example 5

(26) 54 parts by mass of cyclohexyl dimethylene diisocyanate (H.sub.6XDI) (Wanhua Chemical, WANNATE XR-2006, 99.91% purity) with a turbidity of 0.194 NTU were added into a reaction kettle with a stirrer, and 0.03 parts by mass of dibutyltin dichloride as a catalyst, 0.10 parts by mass of acidic phosphate ester (Stepan, Zelec UN) and 0.05 parts by mass of an ultraviolet absorber (Rianlon, RIAS ORB UV531) were added at 25? C., mixed and dissolved. Then, 46 parts by mass of 1,2-bis[(2-mercaptoethyl)thio]-3-mercaptopropane were added based on a molar ratio of 0.93 of the NCO group to the SH group and mixed for 1 h at room temperature and at a rotational speed of 100 rpm to form a polymerizable raw material composition. After cooled to 20? C., the polymerizable raw material composition was degassed for 1 h at 2 kPa and 25? C., injected into a lens mold, heated from 20? C. to 120? C. for 24 h in an oven so that the raw material composition was polymerized and cured. Secondary curing was performed at 120? C. for 2 h after demolding to obtain an optical material. Test results are shown in Table 1.

Example 6

(27) The isocyanate raw material used in this example was basically the same as that in Example 5 except that 55 parts by mass of H.sub.6XDI with a turbidity of 0.563 NTU and 45 parts by mass of 1,2-bis[(2-mercaptoethyl)thio]-3-mercaptopropane were added based on a molar ratio of 0.97 of the NCO group to the SH group. In addition, the same operations were performed in this example as in Example 5. The results are shown in Table 1.

(28) TABLE-US-00001 TABLE 1 Evaluation results of optical materials synthesized by raw materials with different turbidity values in examples and comparative examples XDI Comparative H.sub.6XDI Item Example Example Example No. 1 2 3 4 1 2 3 5 6 Monomer 0.242 0.35 0.55 1.93 8.12 30.23 2330 0.194 0.563 turbidity/NTU Average 84.60 83.50 83.17 80.58 79.97 77.82 72.37 84.77 83.76 transmittance/% Transmit- 400 72.19 65.48 61.73 65.42 60.41 56.03 51.16 72.76 65.61 tance/% nm 450 87.61 86.48 86.14 86.40 82.30 79.71 73.32 87.22 86.55 nm 550 88.09 87.70 87.47 87.59 83.61 81.55 75.76 88.34 88.73 nm 650 88.33 88.14 87.98 84.93 84.66 82.85 77.41 88.85 88.15 nm Haze/% 0.68 0.89 2.34 3.20 9.22 72.41 83.31 0.12 1.05 Yellowness 1.72 1.78 1.80 1.85 1.92 1.97 2.03 1.09 1.69 index Qualification 95% 93% 89% 75% 0% 0% 0% 94% 89% ratio Note: Pieces with a thickness of 6 mm for the test, and C/2 light source; products that are turbid and opaque are all unqualified products.

(29) As can be seen from the comparison results of the preceding examples and comparative examples, the turbidity of the isocyanate raw material has a great effect on the incidence of optical deformation. When the turbidity is controlled within a certain range, the product quality can be effectively guaranteed. Especially when the turbidity of the isocyanate raw material is less than 0.35 NTU, the obtained optical materials have better physical properties and a higher qualification ratio. However, as the turbidity of an isocyanate compound increases, various indicators of the product gradually deteriorate, resulting in a decline in product quality.

(30) In addition, FIG. 1 shows the appearance of a qualified piece obtained in Example 1, and FIG. 2 shows the appearance of two pieces which are respectively reflected in the left image and right image. As can be seen from the comparison in appearance of the cured pieces in FIG. 1 and FIG. 2, the qualified piece in FIG. 1 is transparent in appearance and good in quality, the piece obtained in Comparative Example 3 and shown in the right image in FIG. 2 is turbid and opaque in appearance, and the defective piece obtained in Example 4 and shown in the left image in FIG. 2 has obvious ripple deformation in appearance. This indicates that under the same formula system, a monomer with a high turbidity has a relatively great effect on the quality of the prepared optical material, and the turbidity of the monomer needs to be limited within a certain range to ensure the preparation of high-quality optical materials.

(31) As in actual use, after opening the material packaging barrel, there will be a certain amount of time to place. The present disclosure also investigates the change of turbidity during the placement of raw materials, monomers XDI and H.sub.6XDI.

Example 7

(32) A constant temperature and humidity box was used whose temperature was set to 30? C. (an ambient temperature of a general machining workshop), multiple 1000 mL wide-mouth glass bottles were placed exposed therein, 1000 g of XDI was put in each bottle and sampled and analyzed every 24 hours. A humidity setting was adjusted after a group of constant humidity experiments. The experimental results are shown in Table 2.

(33) TABLE-US-00002 TABLE 2 Change in turbidity (unit: NTU) of XDI stored exposed under different humidity with time Storage humidity 50% (Comparative Placement time 18% 25% 35% Condition) Initial 0.210 0.210 0.210 0.210 24 h 0.227 0.239 0.245 0.256 48 h 0.279 0.285 0.300 0.376 72 h 3.590 4.120 5.130 6.88 (Comparative Condition) 96 h 15.89 16.99 18.43 20.53 (Comparative Condition) 120 h 1327 2020 2355 2654 (Comparative Condition)

Example 8

(34) A constant temperature and humidity box was used whose temperature was set to 30? C., multiple 1000 mL wide-mouth glass bottles were placed exposed therein, 1000 g of H.sub.6XDI was put in each bottle and sampled and analyzed every 24 hours or at regular intervals of an integer multiple of 24 h. A humidity setting was adjusted after a group of constant humidity experiments. The experimental results are shown in Table 3.

(35) TABLE-US-00003 TABLE 3 Change in turbidity (unit: NTU) of H.sub.6XDI stored exposed under different humidity with time Storage humidity 50% (Comparative Placement time 18% 25% 35% Condition) Initial 0.130 0.130 0.130 0.130 24 h 0.133 0.135 0.138 0.141 48 h 0.137 0.139 0.141 0.146 72 h 0.145 0.148 0.149 0.153 96 h 0.148 0.152 0.163 0.166 120 h 0.153 0.171 0.177 0.178 144 h 0.165 0.198 0.212 0.222 240 h 0.310 0.350 0.378 0.413

(36) According to the analysis results in Table 2 and Table 3, it is found that the turbidity of XDI increases significantly faster than that of H.sub.6XDI when they are placed exposed, and the product quality can be controlled by controlling the storage time of the isocyanate raw material used for preparing the polyurethane optical resin. As can be seen from Table 2, use conditions of the isocyanate need to be controlled: the relative humidity is controlled within 35% and XDI is controlled to be used up within 48 h. As can be seen from Table 3, H.sub.6XDI is relatively stable and the quality of the optical resin can be guaranteed within 240 h.

(37) The polyurethane resin obtained through the reaction of the isocyanate compound with the polythiol compound is colorless and transparent, has a high refractive index and low dispersion, and is particularly suitable as a plastic lens with excellent impact resistance, tintability and machinability. Control indicators proposed by the present disclosure can ensure the product quality so that optical products are stably prepared.

(38) Various embodiments of the present disclosure have been described above. The preceding description is illustrative and not exhaustive, and is not limited to the disclosed various embodiments. Without departing from the scope and spirit of the various embodiments described, various modifications and changes are apparent to those of ordinary skill in the art.