A raw material composition for producing a modified polyurethane optical material

Abstract

The application discloses a raw material composition for preparing modified polyurethane optical material, and belongs to the technical field of optical material chemistry, which comprises the following components: 45-55 parts by weight of polyisocyanate, 35-45 parts by weight of tri(2-mercaptoethylthio)methane shown in formula I, and 25-40 parts by weight of 1,3-bis(phenylthio)-2-propyl acrylate. The modified polyurethane optical material obtained through polymerization of the composition has higher transmittance and refractive index and good mechanical properties, and is suitable for optical elements and devices with high requirements on refractive index.

Description

Technical Field

[0001] This invention relates to the field of optical materials chemistry, and more specifically to a raw material composition for preparing modified polyurethane optical materials. Background Technology

[0002] Traditional optical resins, such as polycarbonate and polymethyl methacrylate, have limitations such as relatively low refractive index (n≈1.49-1.59), unsatisfactory Abbe number, and poor weather resistance, making it difficult to meet the requirements of high transparency, lightweight, and precision in high-end optical devices. With the rapid development of emerging optoelectronic industries such as display technology, augmented reality (AR), virtual reality (VR), and laser devices, the demand for high-performance optical materials is becoming increasingly urgent, and traditional materials can no longer meet the stringent requirements of these cutting-edge applications.

[0003] Polythiol compounds have shown great potential in the field of optical materials. Due to the large atomic radius and high polarizability of sulfur atoms, these compounds possess unique optical properties and coordination abilities, attracting considerable attention. Their molecular structures contain reactive thiol functional groups, which not only increase the refractive index of the polymer but also enable the formation of a high-density three-dimensional network structure through multi-point crosslinking, thereby achieving excellent mechanical properties and thermal stability.

[0004] In precision optical component applications, the purity requirements for high-refractive-index thiols are extremely stringent, typically requiring a purity of over 99.5% to avoid optical defects. Sulfide impurities and chloride residues generated by traditional synthesis methods severely affect key performance parameters of optical materials, such as transmittance, refractive index, and colorimetry, leading to problems like scattering, increased absorption loss, and decreased image quality in optical devices, thus failing to meet the requirements of precision optical components. Therefore, developing green and efficient synthesis processes and advanced purification technologies has become a key technological bottleneck for industrialization.

[0005] With the widespread adoption of technologies such as 5G communication, artificial intelligence, and autonomous driving, the market demand for high-end optical components is growing rapidly at a rate of 15-20% annually. Therefore, there is an urgent need to develop efficient, environmentally friendly, and economical polythiol compounds to meet the pressing needs of high-end application markets such as optical materials and to promote the development of related industries. This will provide a significant opportunity for my country to achieve technological breakthroughs and industrial upgrading in the field of new materials. Summary of the Invention

[0006] The present invention aims to provide a raw material composition for a modified polyurethane optical material composed of polyisocyanate, tris(2-mercaptoethylthio)methane and 1,3-bis(phenylthio)-2-propyl acrylate. The modified polyurethane optical material obtained by polymerization of this composition has high transmittance and refractive index and good mechanical properties, and is suitable for optical components with high requirements for refractive index.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A raw material composition for preparing modified polyurethane optical materials, comprising the following components:

[0009] Component A: Polyisocyanate, 45-55 parts by weight;

[0010] Component B: Tris(2-mercaptoethoxy)methane as shown in Formula I, 35-45 parts by weight;

[0011] Component C: 1,3-bis(phenylthio)-2-propyl acrylate, 25-40 parts by weight;

[0012]

[0013] (I).

[0014] In the raw material composition described above, preferably, the polyisocyanate is selected from at least one of diphenylmethane diisocyanate, diphenyl ether diisocyanate, toluene diisocyanate, diethylene diisocyanate, cyclohexane diisocyanate, hexamethylene diisocyanate, diisocyanate dicyclohexylmethane, dithiodiethyl diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, thiodihexyl diisocyanate, thiodipropyl diisocyanate, dithiodipropyl diisocyanate, triphenylmethane triisocyanate, m-phenylenedimethyl isocyanate, phenylenedimethyl diisocyanate, lysine triisocyanate, trimethylhexamethylene diisocyanate, and o-toluidine diisocyanate.

[0015] Preferably, the raw material composition as described above further includes a catalyst, an antioxidant, and / or an initiator.

[0016] In the above-described raw material composition, preferably, the catalyst is selected from at least one of stannous octoate, triethylenediamine, dibutyltin dilaurate, dibutyltin dichloride, and dibutyltin oxide, and the amount of catalyst is 0.1 to 0.5 wt% of isocyanate.

[0017] In the raw material composition described above, preferably, the antioxidant is selected from at least one of tert-butylcatechol, 2,6-di-tert-butyl-p-cresol and 2,4-dimethyl-6-tert-butylphenol, and the amount of antioxidant is 0.1 to 0.3 wt% of the amount of 1,3-bis(phenylthio)-2-propyl acrylate.

[0018] In the raw material composition described above, preferably, the initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptanenitrile, azobisisovaleratenitrile and 2,2'-azobis(2-methylbutyronitrile), and the amount of initiator is 0.1 to 0.4 wt% of the amount of 1,3-bis(phenylthio)-2-propyl acrylate.

[0019] Preferably, the tris(2-mercaptoethylthio)methane compound is prepared by the following method: Triethyl orthoformate and 1,2-ethanedithiol undergo a condensation reaction under acidic conditions. The oxygen atom of triethyl orthoformate is protonated, and the thiol group (-SH) of 1,2-ethanedithiol acts as a nucleophile, attacking the central carbon of the protonated triethyl orthoformate and replacing one ethoxy group to generate a thioacetal intermediate. The remaining two ethoxy groups are subsequently replaced by two other molecules, ultimately yielding tris(2-mercaptoethylthio)methane. The specific reaction process is as follows:

[0020] .

[0021] Specifically, the method includes the following steps:

[0022] 1,2-Ethylenedithiol and solvent were added to a reaction vessel, along with an acidic catalyst and antioxidant. Under continuous N2 protection, 35-55 wt% triethyl orthoformate was added dropwise with stirring and the reaction was carried out at room temperature for 1-3 hours. The remaining triethyl orthoformate was then added dropwise and the reaction was carried out for another 1-3 hours. The weight ratio of triethyl orthoformate, solvent, and 1,2-ethylenedithiol was (1-1.2):(1.2-1.5):(2-3). The temperature was raised to 60-80℃ and the reaction was carried out for 4-9 hours. The reaction progress was monitored by thin-layer chromatography until the starting peak disappeared, at which point the reaction was terminated. The organic phase was separated and eluted, and the solvent was collected by vacuum distillation to obtain tris(2-mercaptoethylthio)methane as shown in Formula I.

[0023] In the raw material composition described above, preferably, the solvent is selected from at least one of benzene, toluene, chloroform, xylene, tetrahydrofuran, and dimethyl sulfoxide.

[0024] In the raw material composition described above, preferably, the antioxidant is selected from at least one of triphenylphosphine, tributylphosphine, triphenyl phosphite, dibutylhydroxytoluene and 2,6-di-tert-butyl-4-methylphenol, and the amount of antioxidant is 0.01 to 0.5 wt% of the amount of 1,2-ethanedithiol.

[0025] In the above-described raw material composition, preferably, the acidic catalyst is one of p-toluenesulfonic acid, hydrochloric acid, and Lewis acid, and the amount of acidic catalyst is 1-5 wt% of the amount of triethyl orthoformate.

[0026] The 1,3-bis(phenylthio)-2-propyl acrylate of the present invention can be prepared by the following method:

[0027] Glycerol and acid catalyst were added to a reaction vessel containing solvent with stirring. N2 was continuously introduced and the temperature was controlled at 55-80°C. Thiophenol was added dropwise, and the reaction was carried out for 2-4 hours. The temperature was cooled to 0-10°C, and alkaline hydrolysate was added in batches with stirring. Acryloyl chloride was added dropwise, and the temperature was raised to room temperature. The reaction was continued for 2-3 hours. The pH was measured to be 6-7. The organic phase was separated and eluted. The solvent and catalyst were collected by vacuum distillation to obtain 1,3-bis(phenylthio)-2-propyl acrylate monomer (II).

[0028] The beneficial effects of this invention are:

[0029] (1) The tris(2-mercaptoethylthio)methane compound in the composition has a three-arm radial structure, containing three active thiol groups and a flexible ethyl segment, exhibiting good spatial symmetry, abundant chemical reaction sites, and appropriate molecular flexibility. The material design takes into account both ease of processing and economy, and can be used to prepare high-sulfur modified functional materials, providing valuable molecular tools for high-end optical components and other fields.

[0030] (2) The preparation method of tri(2-mercaptoethylthio)methane compound involves reacting triethyl orthoformate with a mercapto compound under relatively mild conditions. The byproduct is ethanol, which is easy to separate and recover. The product has high purity, is environmentally friendly, and the raw materials are readily available and relatively low in cost.

[0031] (3) In the raw material composition for preparing modified polyurethane optical materials, the synergistic effect of the six sulfur atoms in the tris(2-mercaptoethylthio)methane compound enhances the optical density and increases the refractive index; the multifunctional structure forms a high-density three-dimensional cross-linked network, improving the hardness and dimensional stability of the polyurethane material. The thioether bond and benzene ring conjugated system of 1,3-bis(phenylthio)-2-propyl acrylate provide a high refractive index. The synergistic effect of the two can further improve the refractive index of the material. At the same time, the mercapto-isocyanate reaction forms thiourethane bonds, and the acrylate groups participate in free radical polymerization to form a "thiourethane-acrylate" interpenetrating network structure. The multi-component cross-linked structure is optimized to ensure the balance between rigidity and toughness of the material.

[0032] (4) The cost of 1,3-bis(phenylthio)-2-propyl acrylate is lower than that of polythiols used in conventional polyurethane preparation. Replacing polythiols with 1,3-bis(phenylthio)-2-propyl acrylate can reduce the overall cost of raw materials by about 1 / 3 compared with conventional polyurethane polymer optical materials without reducing the optical performance (transmittance and refractive index) and mechanical properties. Attached Figure Description

[0033] Figure 1 The FT-IR infrared spectrum of the tris(2-mercaptoethylthio)methane compound prepared in Example 1 is shown.

[0034] Figure 2The 1H NMR spectrum of the tri(2-mercaptoethylthio)methane compound prepared in Example 1. Detailed Implementation

[0035] The present invention will be further described below through specific embodiments, but this does not imply a limitation on the scope of protection of the present invention.

[0036] Example 1: Preparation of tris(2-mercaptoethylthio)methane

[0037] 180 g of 1,2-ethanedithiol was added to a reaction vessel containing 120 g of toluene, equipped with a stirrer, a vent pipe, and a temperature control device. 3 g of p-toluenesulfonic acid, 0.4 g of triphenylphosphine, and 0.02 g of butylated hydroxytoluene (BHT) were added. Under continuous N2 protection, 45 g of triethyl orthoformate was added dropwise with stirring and the reaction was carried out at room temperature for 2 hours. Another 45 g of triethyl orthoformate was added dropwise, and the reaction was continued for 2.5 hours. The temperature was then raised to 70 °C and the reaction was carried out for 4.5 hours. Thin-layer chromatography was performed every hour to monitor the reaction until the starting peak disappeared. The reaction was then stopped, cooled to room temperature, and the organic phase was separated and eluted. The solvent was recovered by vacuum distillation to obtain 131.7 g of colorless, transparent, viscous tris(2-mercaptoethylthio)methane, with a yield of 74.1%.

[0038] Purity Testing and Analysis: The purity of the product prepared in Example 1 was tested using high-performance liquid chromatography (HPLC). Testing Procedure and Method: 25 mg of tris(2-mercaptoethylthio)methane was accurately weighed into a 10 mL volumetric flask containing methanol. 0.1% formic acid was added (to prevent thiol oxidation), and the mixture was sonicated for 5 min until completely dissolved. A C18 column was selected. The mobile phase consisted of A-0.1% formic acid in water and B-methanol. The detection wavelength was 210-220 nm (absorption of thioethers and thiol groups). Purity (%) = (target peak area / total peak area) × 100%. The product purity was calculated to be 99.6% based on the peak area.

[0039] Fourier transform infrared (FT-IR) spectroscopy was performed on the product prepared in Example 1. The results are as follows: Figure 1 As shown, 2984~2867cm -1 The strong absorption peak is due to the saturated CH stretching vibration, 2947~2865 cm⁻¹. -1 The absorption peak at 2574–2565 cm⁻¹ corresponds to the asymmetric and symmetric stretching vibrations of the methylene group (-CH₂-). -1 The absorption peak at 1355~1460 cm⁻¹ is due to the stretching of the thiol group (-SH-). -1 The absorption peak at 920-827 cm⁻¹ is due to the bending and rocking vibrations of the methylene group (-CH₂-). -1 The absorption peaks at 762–657 cm⁻¹ are attributed to C-C framework vibrations and CH out-of-plane bending. -1The absorption peaks at these locations represent the stretching vibration of the CS bond and the out-of-plane bending vibration of the SH bond.

[0040] 1H NMR analysis: δ = 4.27~4.43 ppm (s, 1H, -CH-methylene hydrogen); δ = 2.78~2.88 ppm (t, 6H, 3×-SCH2-methylene hydrogen); δ = 2.66~2.75 ppm (t, 6H, 3×-CH2SH-methylene hydrogen); δ = 1.86~2.17 ppm (s, 3H, 3×-SH-mercaptohydrogen).

[0041] Example 2: Preparation of tris(2-mercaptoethylthio)methane

[0042] 225 g of 1,2-ethanedithiol was added to a reaction vessel containing 150 g of toluene, equipped with a stirrer, a vent pipe, and a temperature control device. 3.7 g of p-toluenesulfonic acid and 0.6 g of triphenylphosphine were added. Under continuous N2 protection, 60 g of triethyl orthoformate was added dropwise with stirring and the reaction was carried out at room temperature for 2 hours. Then, 52 g of triethyl orthoformate was added dropwise and the reaction was carried out for another 2 hours. The temperature was raised to 70 °C and the reaction was carried out for 4.5 hours. Thin-layer chromatography was performed every hour to monitor the reaction until the starting peak disappeared. The reaction was stopped and cooled to room temperature. The organic phase was separated and eluted, and the solvent was recovered by vacuum distillation to obtain 163.4 g of colorless, transparent, viscous tris(2-mercaptoethylthio)methane, with a yield of 73.9%.

[0043] The tris(2-mercaptoethylthio)methane compound prepared in Example 2 was subjected to FT-IR and 1H NMR nuclear magnetic resonance spectroscopy. The test results were basically the same as those in Example 1.

[0044] Example 3: Preparation of tris(2-mercaptoethylthio)methane

[0045] 145 g of 1,2-ethanedithiol was added to a reaction vessel containing 95 g of toluene, equipped with a stirrer, a vent pipe, and a temperature control device. 2.4 g of p-toluenesulfonic acid and 0.04 g of BHT were added. Under continuous N2 protection, 32 g of triethyl orthoformate was added dropwise with stirring, and the reaction was carried out at room temperature for 2 hours. 40 g of triethyl orthoformate was then added dropwise, and the reaction was continued for 2.5 hours. The temperature was raised to 70 °C, and the reaction was carried out for 4.5 hours. Thin-layer chromatography was performed every hour until the starting peak disappeared, at which point the reaction was stopped. The mixture was cooled to room temperature, the organic phase was separated and eluted, and the solvent was recovered by vacuum distillation to obtain 106.7 g of colorless, transparent, viscous tris(2-mercaptoethylthio)methane. Yield: 75.1%.

[0046] Example 4: Preparation of tris(2-mercaptoethylthio)methane

[0047] 100 g of 1,2-ethanedithiol was added to a reaction vessel containing 60 g of toluene, equipped with a stirrer, a vent pipe, and a temperature control device. 1.4 g of p-toluenesulfonic acid and 0.03 g of BHT were added. Under continuous N2 protection, 25 g of triethyl orthoformate was added dropwise with stirring, and the reaction was carried out at room temperature for 2 hours. Another 25 g of triethyl orthoformate was added dropwise, and the reaction was continued for 2 hours. The temperature was then raised to 70 °C, and the reaction was carried out for 4.5 hours. Thin-layer chromatography was performed every hour until the starting peak disappeared, at which point the reaction was stopped. The mixture was cooled to room temperature, the organic phase was separated and eluted, and the solvent was recovered by vacuum distillation to obtain 75.8 g of colorless, transparent, viscous tris(2-mercaptoethylthio)methane. The yield was 76.7%.

[0048] Example 5: Preparation of tris(2-mercaptoethylthio)methane

[0049] 135 g of 1,2-ethanedithiol was added to a reaction vessel containing 90 g of toluene, equipped with a stirrer, a vent pipe, and a temperature control device. 2.2 g of p-toluenesulfonic acid, 0.2 g of triphenylphosphine, and 0.02 g of BHT were added. Under continuous N2 protection, 32 g of triethyl orthoformate was added dropwise with stirring, and the reaction was carried out at room temperature for 2 hours. Then, 35 g of triethyl orthoformate was added dropwise, and the reaction was carried out for another 2 hours. The temperature was raised to 70 °C, and the reaction was carried out for 4.5 hours. Thin-layer chromatography was performed every hour until the starting peak disappeared, at which point the reaction was stopped. The mixture was cooled to room temperature, the organic phase was separated and eluted, and the solvent was recovered by vacuum distillation to obtain 98.1 g of colorless, transparent, viscous tris(2-mercaptoethylthio)methane. Yield: 74.2%.

[0050] Example 6: Preparation of Modified Polyurethane Optical Materials

[0051] (1) Preparation of 1,3-bis(phenylthio)-2-propyl acrylate monomer (Formula II)

[0052] .

[0053] 180 g of glycerol and 10 g of BF3•Et2O were added to a reaction vessel containing 500 g of isobutanol solvent with stirring. N2 was continuously introduced, and the temperature was maintained at 75 °C. 440 g of thiophenol was added dropwise, and the reaction proceeded for 3.5 h. The mixture was then cooled to 5 °C, and 50 g of triethylamine was added with stirring. 180 g of acryloyl chloride was added dropwise over 2 h. The temperature was raised to room temperature, and the reaction proceeded for 1 h. 55 g of triethylamine was then added, and the reaction proceeded for 2 h. The mixture was neutralized to pH 6 with an aqueous sodium bicarbonate solution. The organic phase was separated and eluted. The solvent and catalyst were collected by vacuum distillation to yield 443 g of 1,3-bis(phenylthio)-2-propyl acrylate (II). Yield: 65.9%.

[0054] (2) Preparation of modified polyurethane optical materials

[0055] 50g of diphenylmethane diisocyanate and 40g of tris(2-mercaptoethylthio)methanethiol prepared in Example 1 were added to a reaction vessel. 0.07g of dibutyltin dilaurate and 0.03g of triethylenediamine were added and stirred at 25±2℃ for 45min. Then, 35g of 1,3-bis(phenylthio)-2-propyl acrylate, 0.06g of 2,6-di-tert-butyl-p-cresol and 0.09g of azobisisobutyronitrile were added and stirred for 20min. The mixture was then degassed under vacuum for 15min. The degassed mixture was poured into a tempered mold and cured at 40℃×2.5h → 55℃×2.5h → 65℃×1.5h. Annealing was performed at 65℃→30℃, with slow cooling at 1.5℃ / min to obtain the modified polyurethane optical material.

[0056] Example 7: Preparation of Modified Polyurethane Optical Materials

[0057] 60g of diphenylmethane diisocyanate and 48g of tris(2-mercaptoethylthio)methanethiol prepared in Example 1 were added to a reaction vessel. 0.08g of dibutyltin dilaurate and 0.04g of triethylenediamine were added and stirred at 25±2℃ for 45min. Then, 42g of 1,3-bis(phenylthio)-2-propyl acrylate monomer, 0.07g of tert-butylcatechol and 0.1g of azobisisobutyronitrile were added and stirred for 20min. The mixture was then degassed under vacuum for 15min. The degassed mixture was poured into a tempered mold and cured at 40℃×2.5h → 55℃×2.5h → 70℃×1.5h. Annealing was performed at 70℃→30℃, with slow cooling at 2℃ / min to obtain the modified polyurethane optical material.

[0058] Example 8: Preparation of Modified Polyurethane Optical Materials

[0059] 70g of diphenylmethane diisocyanate and 60g of tris(2-mercaptoethylthio)methanethiol prepared in Example 1 were added to a reaction vessel. 0.01g of dibutyltin dilaurate and 0.04g of triethylenediamine were added and stirred at 25±2℃ for 45min. Then, 50g of 1,3-bis(phenylthio)-2-propyl acrylate monomer, 0.09g of 2,4-dimethyl-6-tert-butylphenol, and 0.12g of 2,2'-azobis(2-methylbutyronitrile) were added and stirred for 20min. The mixture was then degassed under vacuum for 15min. The degassed mixture was poured into a tempered mold and cured at 40℃×2.5h → 60℃×2.5h → 75℃×1.5h. Annealing was performed at 75℃→30℃, with slow cooling at 2℃ / min to obtain the modified polyurethane optical material.

[0060] Comparative Example 1: Preparation of Polyurethane Optical Materials

[0061] The same preparation method as in Example 8 was used, except that 2,3-dimercaptoethylthiopropanethiol (BES) was used instead of tris(2-mercaptoethylthio)methanethiol to prepare polyurethane optical materials. The specific operation method is as follows:

[0062] 70g of diphenylmethane diisocyanate and 60g of 2,3-dimercaptoethylthiopropane mercaptan (BES) were added to a reaction vessel. 0.01g of dibutyltin dilaurate and 0.04g of triethylenediamine were added while stirring. The mixture was stirred at 25±2℃ for 45min. Then, 50g of 1,3-bis(phenylthio)-2-propyl acrylate monomer, 0.09g of 2,4-dimethyl-6-tert-butylphenol, and 0.12g of 2,2'-azobis(2-methylbutyronitrile) were added while stirring. The mixture was stirred for 20min, degassed under vacuum for 15min, and then poured into a tempered mold. The curing process was 40℃×2.5h → 60℃×2.5h → 75℃×1.5h, followed by annealing at 75℃→30℃. Samples were taken by slowly cooling at 2℃ / min to obtain the polyurethane optical material.

[0063] Comparative Example 2: Preparation of Polyurethane Optical Materials

[0064] The same preparation method as in Example 8 was used, except that hydroxyethyl methacrylate was used instead of 1,3-bis(phenylthio)-2-propyl acrylate to prepare polyurethane optical materials. The specific operation method is as follows:

[0065] 70g of diphenylmethane diisocyanate and 60g of tris(2-mercaptoethylthio)methanethiol prepared in Example 1 were added to a reaction vessel. 0.01g of dibutyltin dilaurate and 0.04g of triethylenediamine were added and stirred at 25±2℃ for 45min. Then, 50g of hydroxyethyl methacrylate monomer, 0.09g of 2,4-dimethyl-6-tert-butylphenol and 0.12g of 2,2'-azobis(2-methylbutyronitrile) were added and stirred for 20min. The mixture was then degassed under vacuum for 15min. The degassed mixture was poured into a tempered mold and cured at 40℃×2.5h → 60℃×2.5h → 75℃×1.5h. Annealing was performed at 75℃→30℃, with slow cooling at 2℃ / min to obtain the modified polyurethane optical material.

[0066] Example 9: Optical performance testing experiment

[0067] The optical properties of the optical materials prepared in Examples 1-8 and the polyurethane optical materials prepared in Comparative Examples 1-2 were tested. Transmittance was measured using a Lambda 650S UV-Vis spectrophotometer (PerkinElmer Chemical Analysis Instruments, Inc.), and refractive index was measured using an Rx-7000 digital refractometer (Shanghai Optical Instrument Equipment Co., Ltd.). The testing method involved directly coating or placing the prepared samples onto the prism of the UV-Vis spectrophotometer or the prism of the refractometer. The yellow index was calculated from the spectrophotometer reading using the formula: YI = 100(1.28X - 1.06Z) ÷ Y, where X, Y, and Z are the tristimulus values ​​of the C light source. The test results are shown in Table 1.

[0068] The test results show that the tri(2-mercaptoethylthio)methane of the present invention has excellent optical properties. When compounded with polyisocyanate and 1,3-bis(phenylthio)-2-propyl acrylate, it can be used to prepare medium- and high-refractive-index modified polyurethane optical materials.

[0069] Example 10: Impact strength test experiment

[0070] The polyurethane optical materials prepared in Example 8 and Comparative Examples 1-2 were subjected to impact strength tests. The material's impact strength was determined by the highest steel ball mass that produced no cracks after three impacts (e.g., a 90g steel ball causing no cracks after three impacts, while a 100g steel ball caused cracks). The testing method involved fixing a substrate with a certain curvature at its center, convex side up, to the bottom of the instrument. Steel balls of different masses (80g, 90g, 95g, and 100g) were dropped vertically from a height of 1.30m onto the center of the substrate surface, with each mass being tested three times. The steel ball impact test results showed that the polyurethane optical materials prepared in Example 8 and Comparative Examples 1-2 all had an impact strength of 95g, indicating that their impact resistance performance was qualified.

[0071] Example 11 Static compressive strength test experiment

[0072] The hydrostatic compressive strength of the polyurethane optical materials prepared in Example 8 and Comparative Example 1 was tested. The test method involved fixing a substrate with a certain curvature at its center, convex side facing upwards, onto a steel structure support. A cylindrical groove was located within the steel structure support. A sheet of white paper was placed at the bottom of the groove, and a carbon paper was placed on top of the white paper. A load was applied to the sample at a speed of 350 mm / min, with pressures of 100 N, 105 N, 110 N, and 115 N, respectively, until imprints or cracks appeared on the white paper. The hydrostatic compressive strength results showed that the hydrostatic compressive strengths of the polyurethane optical materials prepared in Comparative Example 1 and Example 8 were 105 N and 110 N, respectively.

Claims

1. A raw material composition for preparing modified polyurethane optical materials, characterized in that, It includes the following components: Component A: Polyisocyanate, 45-55 parts by weight; Component B: Tris(2-mercaptoethoxy)methane as shown in Formula I, 35-45 parts by weight; Component C: 1,3-bis(phenylthio)-2-propyl acrylate as shown in Formula II, 25 to 40 parts by weight; ; 。 2. The raw material composition according to claim 1, characterized in that, The polyisocyanate is selected from at least one of diphenylmethane diisocyanate, diphenyl ether diisocyanate, toluene diisocyanate, diethylene diisocyanate, cyclohexane diisocyanate, hexamethylene diisocyanate, diisocyanate dicyclohexylmethane, dithiodiethyl diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, thiodihexyl diisocyanate, thiodipropyl diisocyanate, dithiodipropyl diisocyanate, triphenylmethane triisocyanate, m-phenylenediamine diisocyanate, phenylenediamine diisocyanate, lysine triisocyanate, trimethylhexamethylene diisocyanate, and o-toluidine diisocyanate.

3. The raw material composition according to claim 1, characterized in that, The components also include catalysts, antioxidants and / or initiators.

4. The raw material composition according to claim 3, characterized in that, The catalyst is selected from at least one of stannous octoate, triethylenediamine, dibutyltin dilaurate, dibutyltin dichloride and dibutyltin oxide, and the amount of catalyst used is 0.1 to 0.5 wt% of polyisocyanate.

5. The raw material composition according to claim 3, characterized in that, The antioxidant is selected from at least one of tert-butylcatechol, 2,6-di-tert-butyl-p-cresol and 2,4-dimethyl-6-tert-butylphenol, and the amount of antioxidant used is 0.1 to 0.3 wt% of the amount of 1,3-bis(phenylthio)-2-propyl acrylate.

6. The raw material composition according to claim 3, characterized in that, The initiator is selected from at least one of azobisisobutyronitrile, azobisisoheptanenitrile, azobisisovaleratenitrile and 2,2'-azobis(2-methylbutyronitrile), and the amount of initiator is 0.1 to 0.4 wt% of the amount of 1,3-bis(phenylthio)-2-propyl acrylate.

7. The raw material composition according to any one of claims 1-6, characterized in that, The tris(2-mercaptoethylthio)methane compound was prepared by the following method: 1,2-Ethylenedithiol and solvent were added to a reaction vessel, along with an acidic catalyst and antioxidant. Under continuous N2 protection, 35-55 wt% triethyl orthoformate was added dropwise with stirring and the reaction was carried out at room temperature for 1-3 hours. The remaining triethyl orthoformate was then added dropwise and the reaction was carried out for another 1-3 hours. The weight ratio of triethyl orthoformate, solvent, and 1,2-ethylenedithiol was (1-1.2):(1.2-1.5):(2-3). The temperature was raised to 60-80℃ and the reaction was carried out for 4-9 hours. The reaction progress was monitored by thin-layer chromatography until the starting peak disappeared, at which point the reaction was terminated. The organic phase was separated and eluted, and the solvent was collected by vacuum distillation to obtain tris(2-mercaptoethylthio)methane as shown in Formula I.

8. The raw material composition according to claim 7, characterized in that, The solvent is selected from at least one of benzene, toluene, chloroform, xylene, tetrahydrofuran, and dimethyl sulfoxide.

9. The raw material composition according to claim 7, characterized in that, The antioxidant is selected from at least one of triphenylphosphine, tributylphosphine, triphenyl phosphite, dibutylhydroxytoluene and 2,6-di-tert-butyl-4-methylphenol, and the amount of antioxidant is 0.01 to 0.5 wt% of the amount of 1,2-ethanedithiol.

10. The raw material composition according to claim 7, characterized in that, The acidic catalyst is one of p-toluenesulfonic acid, hydrochloric acid, and Lewis acid, and the amount of acidic catalyst used is 1 to 5 wt% of the amount of triethyl orthoformate.

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