High heat resistant flame retardant polyurethane resin and method for preparing the same

Abstract

The application provides a high-heat-resistant flame-retardant polyurethane resin and a preparation method thereof. The resin comprises a flame-retardant polymer, wherein the flame-retardant polymer is copolymerized from a tetrabromobisphenol A diallyl ether (TBPA) monomer and a 2-vinyl-4,6-diamino-1,3,5-triazine (VDT) monomer, and the resin further comprises isocyanate, a polythiol compound and the like. The polyurethane resin material of the application not only has the flame-retardant property, and the limiting oxygen index (LOI) value can reach 32, but also improves the glass transition temperature of the resin.

Description

Technical Field

[0001] This invention relates to the field of optical resins, specifically to a high heat-resistant and flame-retardant polyurethane resin and its preparation method. Background Technology

[0002] Polyurethane optical resin is mainly made by casting isocyanates and polythiols. Its key feature is that the refractive index of the lens can be adjusted by selecting different isocyanates and polythiols. Taking the commercially available MR series as an example, MR-7 is a 1.67 refractive index lens, MR-8 is a 1.60 refractive index lens, and MR-174 is a 1.74 refractive index lens. Based on this, customers can choose suitable lenses according to price and personal needs.

[0003] With the development of the information age, consumer demand for lenses has become more diversified. For example, there are high-impact lenses for sports and anti-fog lenses for healthcare workers. From a safety perspective, consumers are demanding flame-retardant and heat-resistant resin lenses to meet their needs in extreme situations. For instance, people working in fires or high-temperature environments require materials with high heat resistance and flame retardancy. Specifically, high heat resistance refers to the glass transition temperature (Tg) of the material. For polymer materials, the glass transition temperature is the temperature at which chain segments begin to move. Above the Tg temperature, the modulus of the lens material drops sharply, making it prone to deformation. Taking commercially available MR-10 and MR-7 as examples, MR-10 has a glass transition temperature of 100℃, while MR-7 is only 85℃, indicating that MR-10 has better heat resistance. Currently, the Tg temperature range of polyurethane optical resins is approximately 70-120℃. The difference is mainly due to the different chemical structures of the isocyanate components and polythiols.

[0004] Flame retardant additives are modifiers that can be incorporated into flammable materials to prevent fires and suppress their intensity. They mainly include halogen and phosphorus-based flame retardants, organic flame retardants, inorganic flame retardants, and composite modified flame retardants. Adding halogen atoms, such as bromine, to organic materials is the primary way to impart flame retardant properties. The LOI (Limiting Oxygen Index) is an indicator of a material's flame retardant performance. It represents the minimum oxygen concentration (by volume) required for the material to maintain equilibrium combustion in a mixture of nitrogen and oxygen under specified conditions. A higher LOI value indicates better flame retardant performance. Since resin materials are organic polymers, their LOI values ​​are generally below 22, classifying them as flammable. For example, the LOI of polymethyl methacrylate (PMMA) optical resin is only 17.5. If the LOI value is above 22, it indicates that the material has varying degrees of flame retardant properties. Specifically, if the LOI value is in the range of 22-26, the material exhibits difficulty in combustion, indicating that it possesses certain flame retardant properties. If the LOI value is in the range of 26-40, the material is difficult to burn, indicating that it has good flame retardant properties. If the LOI value is above 40, the material is not easily burned, indicating that it has very good flame retardant properties.

[0005] Patent CN115124825A provides a flame-retardant resin material by applying a surface coating to polycarbonate (PC) material, without modifying the chemical structure of the material itself. Patent CN105778094A introduces a phosphorus-containing compound and uses a polyacrylate phosphate compound and a polythiol compound for curing to obtain a flame-retardant optical resin. This addresses the problem that existing LED encapsulation resins, such as epoxy and silicone resins, are not flame-retardant and pose a fire hazard. The flame-retardant optical resin prepared by this patent meets the requirements of LED encapsulation resins for flame retardancy and refractive index. However, the acrylate phosphate compound mentioned in this patent is not suitable for polyurethane optical resin materials. Excessive acrylate phosphate compounds can easily cause side reactions such as polyurethane foaming, failing to meet application requirements.

[0006] Therefore, in order to promote the diversified development of polyurethane materials and meet the needs of some consumers, it is necessary to develop high heat-resistant and flame-retardant polyurethane optical resins. Summary of the Invention

[0007] To address the aforementioned problems, the present invention provides the following technical solution:

[0008] The purpose of this invention is to provide a high heat-resistant and flame-retardant polyurethane resin and its preparation method. The polyurethane resin of this invention not only has conventional optical properties, but also excellent flame-retardant and heat-resistant properties.

[0009] To address the above problems, the present invention provides a high heat-resistant and flame-retardant polyurethane resin, comprising a flame-retardant polymer, wherein the flame-retardant polymer is copolymerized by tetrabromobisphenol A dielyl ether (TBPA) monomer and 2-vinyl-4,6-diamino-1,3,5-triazine (VDT) monomer.

[0010] The flame-retardant polymer is prepared by dissolving tetrabromobisphenol A dielyl ether (TBPA) monomer containing halogenated bromine atoms and 2-vinyl-4,6-diamino-1,3,5-triazine (VDT) monomer in an organic solvent, and then carrying out free radical polymerization under the conditions of a free radical initiator.

[0011] Preferably, the free radical initiator is an organic peroxide initiator, an azo compound initiator, a redox system initiator, or a photosensitizer; the organic peroxide initiator is selected from benzoyl peroxide (BPO) or dicarbonate peroxides, the azo compound initiator is selected from azobisisobutyronitrile (AIBN) or azobisisoheptanenitrile (ABVN), the redox system initiator is selected from an organic oil-soluble redox system formed by peroxide acyl compounds and tertiary amine compounds, and the photosensitizer is selected from photoinitiator IRGACURE-2959, etc.

[0012] Preferably, the amount of the initiator added is 1%-6% of the total weight of tetrabromobisphenol A dielyl ether (TBPA) monomer and 2-vinyl-4,6-diamino-1,3,5-triazine (VDT) monomer.

[0013] More preferably, the free radical initiator is a composite initiator of benzoyl peroxide (BPO) and N,N-dimethylaniline (DMA), with both added at 1%-3% of the total weight of TBPA and VDT, preferably 1.5-2.5%.

[0014] Preferably, the reaction temperature is 0℃~50℃ and the reaction time is 1~12h. More preferably, the reaction temperature is room temperature (25℃±5℃) and the reaction time is 2~4h.

[0015] The molar ratio of TBPA monomer to VDT monomer is 1:1-20:1, preferably 3:1-15:1, and more preferably 5:1-10:1.

[0016] The organic solvent is an organic solvent that can fully dissolve both TBPA monomer and VDT monomer, and ensure their stability without chemical reaction. Specifically, it includes, but is not limited to, the following organic solvents: halogenated hydrocarbons such as chlorobenzene, ketones such as acetone, ethers such as methyl tert-butyl ether, alcohols such as ethanol, amides such as dimethylformamide, sulfones such as dimethyl sulfoxide, etc., with dimethyl sulfoxide being preferred.

[0017] The high heat-resistant and flame-retardant polyurethane resin of the present invention comprises an isocyanate component, a polythiol compound, a flame-retardant polymer, a catalyst, an optional release agent, and an optional ultraviolet absorber.

[0018] The isocyanate component described in this invention is not particularly limited and can be selected from aliphatic, alicyclic, or aromatic isocyanates. Specific examples of isocyanate components include, but are not limited to, toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, naphthalene diisocyanate, dimethylbiphenyl diisocyanate, 1,4-cyclohexane diisocyanate, terephthalic diisocyanate, tetramethyl-isophthalic diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, phenylenediamine diisocyanate, cyclohexane diisocyanate, and norbornene diisocyanate, preferably phenylenediamine diisocyanate or cyclohexane diisocyanate, and more preferably phenylenediamine diisocyanate.

[0019] The polythiol compounds described in this invention are not particularly limited. Specific examples of polythiol compounds include, but are not limited to, those selected from one or more of the following: ethylene glycol dimercaptoacetate, 1,2-bis(2-mercaptoethoxy)ethane, di(mercaptoacetic acid)-1,4-butanediol, trimethylolpropane tris(3-mercaptopropionate), trimethylolpropane tris(2-mercaptoacetate), pentaerythritol tetramercaptoacetate, 2,3-dithio(2-mercapto)-1-propanethiol, and pentaerythritol tetra(3-mercaptopropionic acid). Preferably, 2,3-dithio(2-mercapto)-1-propanethiol or pentaerythritol tetra(3-mercaptopropionic acid) is preferred, and more preferably, 2,3-dithio(2-mercapto)-1-propanethiol is preferred.

[0020] To enhance the reactivity of the functional groups, the molar ratio of NCO groups to SH groups in the isocyanate component and the polythiol compound is controlled within the range of 0.8-1.5, preferably 0.9-1.1.

[0021] The flame-retardant polymer is added in an amount of 0.1% to 10 wt% based on the total mass of the isocyanate component and the polythiol compound, preferably 0.5% to 8 wt%, more preferably 1% to 6 wt%.

[0022] Adding the flame-retardant polymer described in this application to polyurethane resin not only enables the polyurethane optical resin to have flame-retardant properties, but also allows the amino groups and NCO groups in the high molecular weight flame-retardant polymer to effectively bond, enhancing the compatibility between the additive and the matrix resin, improving the thermal stability of the resin, and preventing abnormal phenomena such as additive loss in the resin lens caused by the direct addition of TBPA monomer.

[0023] The polyurethane resin may also contain catalysts, optional ultraviolet absorbers, optional mold release agents, etc.

[0024] The catalyst can be a commonly used catalyst in the art, such as organotin compounds. Specific examples include dialkyltin halides such as dibutyltin dichloride and dimethyltin dichloride, and dialkyltin dicarboxylate such as dimethyltin diacetate, dibutyltin dioctanoate, and dibutyltin dilaurate, with dibutyltin dichloride being preferred. Based on the total mass of the isocyanate component and polythiol compound, the amount of catalyst added is 0.001 to 2.0% by weight, preferably 0.005 to 1.0% by weight.

[0025] Organic UV absorbers are mainly categorized into benzophenones, triazines, and benzotriazoles. Benzophenones have relatively weak absorption capacity, while triazines have poor stability. Therefore, benzotriazoles are often chosen for industrial production. Taking benzotriazoles as an example, specific benzotriazole UV absorbers include UV49, UV326, UV327, UV360, UV380, and UV329, with UV329 (trade name Tinuvin 329) being preferred. Based on the total mass of isocyanate components and polythiol compounds, the addition amount is 0.001-2.0% by weight, preferably 0.01 to 1.0% by weight.

[0026] Due to the special requirements of optical resin for light transmittance, the phosphate ester-based release agent with the commercial brand name Zelec UN was selected as the release agent. Based on the total mass of isocyanate component and polythiol compound, the addition amount is 0.01-3.0 wt%, preferably 0.05 to 2.0 wt%.

[0027] This invention also provides a method for preparing the above-mentioned polyurethane resin, which is prepared by mixing an isocyanate component, a polythiol compound, a flame-retardant polymer, an optional catalyst, an optional optical resin release agent, and an optional ultraviolet absorber, followed by a polymerization reaction. Preferably, the flame-retardant polymer is first ground into a powder before being added to the reaction.

[0028] This invention utilizes an existing polymerization process involving isocyanates and polythiols to prepare polyurethane optical resins. This process is well-known in the art, and its main steps include mixing the components of the raw material composition, followed by degassing and curing to obtain the polyurethane optical resin. The curing process requires a slow heating from a low temperature to a high temperature, for example, a programmed temperature increase from room temperature to 100-120°C, to allow polymerization and curing. After a second curing, the resin is demolded to obtain the polyurethane material.

[0029] The high heat-resistant and flame-retardant polyurethane resin described in this invention can be applied to optical resins.

[0030] In the flame-retardant polymer of this invention, the introduction of halogenated bromine can achieve the flame-retardant properties of the material. The amino group in the VDI monomer achieves chemical bonding with the isocyanate component NCO, which can effectively add the flame-retardant polymer PTBPA-PVDT to the polyurethane resin system without affecting the optical properties of the polyurethane resin.

[0031] The glass transition temperature (Tg) and limiting oxygen index (LOI) of the high heat-resistant and flame-retardant polyurethane optical resin obtained by the method of this invention show certain differences depending on the amount of flame-retardant polymer added. Generally speaking, within a certain range, the higher the amount of flame-retardant polymer added, the higher the Tg and LOI values. Within the test range, when the amount of flame-retardant polymer added to the polyurethane resin prepared from isophthalic diisocyanate is 9 wt%, the Tg and LOI values ​​are 32 °C and 137 °C, respectively. Therefore, according to the preparation method of this invention, high heat-resistant and flame-retardant polyurethane optical materials with excellent performance can be prepared. Attached Figure Description

[0032] Figure 1 The flame-retardant polymer (PTBPA-PVDT) prepared in Example 1 1 H-NMR spectrum. Detailed Implementation

[0033] The present invention is further illustrated by the following embodiments, but these embodiments do not limit the scope of protection of the present invention.

[0034] The following embodiments of the present invention will be analyzed and characterized using the instruments described below.

[0035] Gel permeation chromatography analysis: Gel permeation chromatography characterization of copolymer macromolecules was performed using an Agilent 1260 high-performance liquid gel permeation chromatograph. The sample was dissolved in tetrahydrofuran (THF) to prepare a solution with a concentration of 4 mg / mL, and the analysis was performed on the GPC instrument using a differential detector, an eluent rate of 1 mL / min, and a column temperature of 35 °C.

[0036] Hydrogen nuclear magnetic resonance (HNMR) spectral analysis: The copolymer was characterized by HNMR spectral analysis using a Varian INOVA HNMR spectrometer (500 MHz). 5–10 mg of sample solvent was dissolved in deuterated dimethyl sulfoxide (DMSO), and after thorough mixing, the solution was analyzed using a 1H-NMR spectrometer.

[0037] Optical Resin Application Index Analysis: Light transmittance was measured using a Hunterlab USVIS1839 colorimeter with a C / 2 light source in total transmittance mode. The average transmittance across the wavelength range of 380nm to 780nm was taken as the sample transmittance. Additionally, the yellowness index (YI value) of the samples was tested under the same mode. For optical lenses, higher transmittance means less reflection and absorption, resulting in clearer optical materials. Conversely, a lower YI value indicates better hue in the plastic lens, while a higher YI value indicates poorer hue. GB 10810.3-2006, "Spectacular Lenses and Related Spectacular Products Part 3: Transmittance Specifications and Measurement Methods," requires a transmittance of 80% or higher for the visible light spectral region (380nm–780nm). GB 2506-2001 specifies the following YI value requirements: YI ≤ 2.20 when the lens refractive index is ≥ 1.56; YI ≤ 1.20 when the lens refractive index is < 1.56.

[0038] The glass transition temperature (Tg) was measured using a Mettler HPDSC1 high-pressure differential scanning calorimeter. The DSC test method was as follows: 30℃-300℃, temperature rise scan, temperature rise rate 10℃ / min, nitrogen atmosphere, nitrogen flow rate 50ml / min; each sample was tested in parallel 3 times and the average value was taken.

[0039] Limiting Oxygen Index (LOI) Test: Tested according to GB / T2406.2-2009, using a 4mm sample strip. The oxygen index analyzer used was Hebei Fangyuan Instrument Equipment Co., Ltd., model JF-3.

[0040] The polyurethane optical resin samples used for testing optical performance were all prepared using a fixed mold (the fixed mold is a flat-bottomed glass cup with a bottom diameter of 500 mm and a height of 800 mm). The materials required for flame retardant performance testing were selected according to GB / T2406.2-2009, using 4 mm specimens.

[0041] The main raw materials are:

[0042] Isophthalimide diisocyanate (XDI, NCO content 44.7%, purity ≥99.5%, Wanhua Chemical, brand name XR-2005), cyclohexanedimethylene diisocyanate (H6XDI, NCO content 43.3%, purity ≥99.7%, Wanhua Chemical, brand name XR-2006), hexamethylene diisocyanate (HDI, NCO content 49.8%, purity ≥99.5%, Wanhua Chemical), isophorone diisocyanate (IPDI, NCO content 37.8%, purity ≥99.5%, Wanhua Chemical)

[0043] The polythiol compounds selected were 2,3-dithio(2-mercapto)-1-propanethiol (trade name: polythiol 504, purity ≥98%, Shandong Yifeng) and pentaerythritol tetrakis(3-mercaptopropionic acid) (trade name: polythiol 405, purity ≥98%, Shanghai Aladdin Biochemical Technology Co., Ltd.).

[0044] The catalyst was dibutyltin dichloride (DBC, 96% purity, Sigma-Aldrich).

[0045] Internal mold release agent (trade names: Zelec UN, Sigma-Aldrich, 98% purity)

[0046] Ultraviolet absorber UV-329 (trade name TINUVIN 329, purity 98%, Shanghai Aladdin Biochemical Technology Co., Ltd.)

[0047] Tetrabromobisphenol A dielyl ether (99% purity, Tianjin Xiens Biochemical Technology Co., Ltd.)

[0048] 2-Vinyl-4,6-diamino-1,3,5-triazine (95% purity, THICA (Shanghai) Chemical Industry Development Co., Ltd.).

[0049] Example 1

[0050] A high heat-resistant and flame-retardant polyurethane optical resin containing 5 wt% PTBPA-PVDT copolymer (monomer molar ratio of TBPA to VDT is 6:1) was prepared.

[0051] (1) Synthesis of PTBPA-PVDT polymer.

[0052] 37.44 g of tetrabromobisphenol A diallyl ether (TBPA) and 1.37 g of 2-vinyl-4,6-diamino-1,3,5-triazine (VDT) were added sequentially to a reaction vessel, followed by 98 g of dimethyl sulfoxide (DMSO) solvent. The mixture was stirred at room temperature until the monomers were completely dissolved. Then, 0.776 g of benzoyl peroxide (BPO) was added to the mixture, and after complete dissolution, 0.776 g of N,N-dimethylaniline (DMA) was added dropwise. The mixture was stirred and reacted at room temperature for 3 hours. The amounts of BPO and DMA added were both 2 wt% of the total mass of tetrabromobisphenol A diallyl ether (TBPA) and 2-vinyl-4,6-diamino-1,3,5-triazine. After the reaction was complete, the mixture was filtered to collect the filter cake, which was then washed three times with 50 ml of methanol each time. Finally, the filter cake was vacuum dried at room temperature to obtain PTBPA-PVDT. Gel permeation chromatography (GPC) showed that the number-average molecular weight (Mn) of the PTBPA-PVDT copolymer was approximately 37,000, and the polydispersity index (PID) was 1.36, indicating that polymerization of the monomers had occurred. Further analysis using proton nuclear magnetic resonance (NMR) (deuterated DMSO as solvent) revealed the following structural composition of the macromolecules. Figure 1 As shown, the presence of two structural units in the molecular chain is confirmed, indicating that the two monomers have successfully copolymerized. The limiting oxygen index (LOI) of the tested polymer is 42.

[0053] (2) Preparation of high heat-resistant and flame-retardant polyurethane optical resin

[0054] At room temperature, 0.015 g of dibutyltin dichloride catalyst, 0.05 g of UV absorber UV-329, 0.1 g of internal mold release agent, 52 g of isophthalic diisocyanate (XDI), and 5 g of PTBPA-PVDT copolymer were added to a stirred reaction vessel and dissolved. Then, 48 g of 2,3-dithio(2-mercapto)-1-propanethiol was added and mixed to form a raw material composition. The raw material composition was filtered through a filter membrane and injected into a lens processing mold (the liquid level of the raw material composition in the mold was approximately 7 mm). Degassing was carried out for 1 hour at 25°C and ≤2 kPa. The filter membrane had a pore size of 1 μm.

[0055] After degassing, the material was heated in an oven from 25°C to 120°C to polymerize and cure it, with a heating rate of 0.2°C / min. When the oven temperature reached 120°C, it was maintained for 2 hours to obtain a cured sample. The sample was then allowed to cool naturally to room temperature and cured a second time at room temperature for 48 hours before demolding to obtain the optical resin material.

[0056] Example 2

[0057] A high heat-resistant and flame-retardant polyurethane optical resin containing 9 wt% PTBPA-PVDT copolymer (monomer molar ratio of TBPA to VDT is 2:1) was prepared.

[0058] (1) Synthesis of PTBPA-PVDT polymer.

[0059] 37.44 g of tetrabromobisphenol A diallyl ether (TBPA) and 4.11 g of 2-vinyl-4,6-diamino-1,3,5-triazine (VDT) were added sequentially to a reaction vessel, followed by 104 g of dimethyl sulfoxide (DMSO) solvent. The mixture was stirred at room temperature until the monomers were completely dissolved. Then, 0.83 g of benzoyl peroxide (BPO) was added to the mixture, and after complete dissolution, 0.83 g of N,N-dimethylaniline (DMA) was added dropwise. The mixture was stirred and reacted at room temperature for 3 hours. The amounts of BPO and DMA added were both 2 wt% of the total mass of tetrabromobisphenol A diallyl ether (TBPA) and 2-vinyl-4,6-diamino-1,3,5-triazine. After the reaction was completed, the mixture was washed with methanol and dried under vacuum as in Example 1.

[0060] (2) Preparation of high heat-resistant and flame-retardant polyurethane optical resin

[0061] At room temperature, 0.015 g of dibutyltin dichloride catalyst, 0.05 g of UV absorber UV-329, 0.1 g of internal mold release agent, 52 g of isophthalic diisocyanate (XDI), and 9 g of PTBPA-PVDT copolymer were added to a stirred reaction vessel and dissolved. Then, 48 g of 2,3-dithio(2-mercapto)-1-propanethiol was added and mixed to form a raw material composition. The raw material composition was filtered through a filter membrane and injected into a lens processing mold (the liquid level of the raw material composition in the mold was approximately 7 mm). Degassing was carried out for 1 hour at 25°C and ≤2 kPa. The filter membrane had a pore size of 1 μm.

[0062] After degassing, the material was heated in an oven from 25°C to 120°C to polymerize and cure it, with a heating rate of 0.2°C / min. When the oven temperature reached 120°C, it was maintained for 2 hours to obtain a cured sample. The sample was then allowed to cool naturally to room temperature and cured a second time at room temperature for 48 hours before demolding to obtain the optical resin material.

[0063] Example 3

[0064] A high heat-resistant and flame-retardant polyurethane optical resin containing 0.2 wt% PTBPA-PVDT copolymer (monomer molar ratio of TBPA to VDT is 18:1) was prepared.

[0065] (1) Synthesis of PTBPA-PVDT polymer.

[0066] 56.16 g of tetrabromobisphenol A diallyl ether (TBPA) and 0.685 g of 2-vinyl-4,6-diamino-1,3,5-triazine (VDT) were added sequentially to a reaction vessel, followed by 142 g of dimethyl sulfoxide (DMSO) solvent. The mixture was stirred at room temperature until the monomers were completely dissolved. Then, 1.14 g of benzoyl peroxide (BPO) was added to the mixture, and after complete dissolution, 1.14 g of N,N-dimethylaniline (DMA) was added dropwise. The mixture was stirred and reacted at room temperature for 3 hours. The amounts of BPO and DMA added were both 2 wt% of the total mass of tetrabromobisphenol A diallyl ether (TBPA) and 2-vinyl-4,6-diamino-1,3,5-triazine (VDT). After the reaction was completed, the mixture was washed with methanol and dried under vacuum as in Example 1.

[0067] (2) Preparation of high heat-resistant and flame-retardant polyurethane optical resin

[0068] At room temperature, 0.015 g of dibutyltin dichloride catalyst, 0.05 g of UV absorber UV-329, 0.1 g of internal mold release agent, 52 g of isophthalic diisocyanate (XDI), and 0.2 g of PTBPA-PVDT copolymer were added to a stirred reaction vessel and dissolved. Then, 48 g of 2,3-dithio(2-mercapto)-1-propanethiol was added and mixed to form a raw material composition. The raw material composition was filtered through a filter membrane and injected into a lens processing mold (the liquid level of the raw material composition in the mold was approximately 7 mm). Degassing was carried out for 1 hour at 25°C and ≤2 kPa. The filter membrane had a pore size of 1 μm.

[0069] After degassing, the material was heated in an oven from 25°C to 120°C to polymerize and cure it, with a heating rate of 0.2°C / min. When the oven temperature reached 120°C, it was maintained for 2 hours to obtain a cured sample. The sample was then allowed to cool naturally to room temperature and cured a second time at room temperature for 48 hours before demolding to obtain the optical resin material.

[0070] Example 4

[0071] A high heat-resistant and flame-retardant polyurethane optical resin containing 7 wt% PTBPA-PVDT copolymer (monomer molar ratio of TBPA to VDT is 4:1) was prepared.

[0072] (1) Synthesis of PTBPA-PVDT polymer.

[0073] 24.96 g of tetrabromobisphenol A diallyl ether (TBPA) and 1.37 g of 2-vinyl-4,6-diamino-1,3,5-triazine (VDT) were added sequentially to a reaction vessel, followed by 66 g of dimethyl sulfoxide (DMSO) solvent. The mixture was stirred at room temperature until the monomers were completely dissolved. Then, 0.53 g of benzoyl peroxide (BPO) was added to the mixture, and after complete dissolution, 0.53 g of N,N-dimethylaniline (DMA) was added dropwise. The mixture was stirred and reacted at room temperature for 3 hours. The amounts of BPO and DMA added were both 2 wt% of the total mass of tetrabromobisphenol A diallyl ether (TBPA) and 2-vinyl-4,6-diamino-1,3,5-triazine (VDT). After the reaction was completed, the mixture was washed with methanol and dried under vacuum as in Example 1.

[0074] (2) Preparation of high heat-resistant and flame-retardant polyurethane optical resin

[0075] At room temperature, 0.05 g of dibutyltin dichloride (DBS) catalyst, 0.05 g of UV absorber UV-329, 0.1 g of internal mold release agent, 47.8 g of cyclohexanedimethyl diisocyanate (H6XDI), and 7 g of PTBPA-PVDT copolymer were added to a stirred reaction vessel and mixed and dissolved. Then, 28.4 g of 2,3-dithio(2-mercapto)-1-propanethiol and 23.8 g of pentaerythritol tetrakis(3-mercaptopropionic acid) ester were added sequentially and mixed to form a raw material composition. The raw material composition was filtered through a filter membrane and injected into a lens processing mold (the liquid level of the raw material composition in the mold was approximately 7 mm). Degassing was carried out for 1 hour at 25°C and ≤2 kPa. The filter membrane had a pore size of 1 μm.

[0076] After degassing, the material was heated in an oven from 25°C to 120°C to polymerize and cure it, with a heating rate of 0.1°C / min. When the oven temperature reached 120°C, it was maintained for 2 hours to obtain a cured sample. The sample was then allowed to cool naturally to room temperature and cured a second time at room temperature for 48 hours before demolding to obtain the optical resin material.

[0077] Example 5

[0078] A high heat-resistant and flame-retardant polyurethane optical resin containing 0.8 wt% PTBPA-PVDT copolymer (monomer molar ratio of TBPA to VDT is 12:1) was prepared.

[0079] (1) Synthesis of PTBPA-PVDT polymer.

[0080] 37.44 g of tetrabromobisphenol A diallyl ether (TBPA) and 0.685 g of 2-vinyl-4,6-diamino-1,3,5-triazine (VDT) were added sequentially to a reaction vessel, followed by 95 g of dimethyl sulfoxide (DMSO) solvent. The mixture was stirred at room temperature until the monomers were completely dissolved. Then, 0.76 g of benzoyl peroxide (BPO) was added to the mixture, and after complete dissolution, 0.76 g of N,N-dimethylaniline (DMA) was added dropwise. The mixture was stirred and reacted at room temperature for 3 hours. The amounts of BPO and DMA added were both 2 wt% of the total mass of tetrabromobisphenol A diallyl ether (TBPA) and 2-vinyl-4,6-diamino-1,3,5-triazine (VDT). After the reaction was completed, the mixture was washed with methanol and dried under vacuum, as in Example 1.

[0081] (2) Preparation of high heat-resistant and flame-retardant polyurethane optical resin

[0082] At room temperature, 0.05 g of dibutyltin dichloride (DBS) catalyst, 0.05 g of UV absorber UV-329, 0.1 g of internal mold release agent, 23 g of hexamethylene diisocyanate (HDI), 15.5 g of cyclohexanedimethylene diisocyanate (H6XDI), 11.5 g of isophorone diisocyanate (IPDI), and 0.8 g of PTBPA-PVDT copolymer were added to a stirred reaction vessel and mixed and dissolved. Then, 38 g of 2,3-dithio(2-mercapto)-1-propanethiol and 12 g of pentaerythritol tetrakis(3-mercaptopropionic acid) were added sequentially and mixed to form a raw material composition. The raw material composition was filtered through a filter membrane and injected into a lens processing mold (the liquid level of the raw material composition in the mold was approximately 7 mm). Degassing was carried out for 1 hour at 25°C and a pressure of ≤2 kPa. The filter membrane had a pore size of 1 μm.

[0083] After degassing, the material was heated in an oven from 25°C to 120°C to polymerize and cure it, with a heating rate of 0.1°C / min. When the oven temperature reached 120°C, it was maintained for 2 hours to obtain a cured sample. The sample was then allowed to cool naturally to room temperature and cured a second time at room temperature for 48 hours before demolding to obtain the optical resin material.

[0084] Comparative Example 1: Preparation of polyurethane optical resin material without PTBPA-PVDT. Compared with Example 1, this comparative example did not add the self-made PTBPA-PVDT copolymer, and the other sample types and amounts, experimental steps and reaction times were the same as in Example 1.

[0085] Comparative Example 2: Preparation of polyurethane optical resin material without PTBPA-PVDT. Compared with Example 4, this comparative example did not add the self-made PTBPA-PVDT copolymer, and the other sample types and amounts, experimental steps and reaction times were the same as in Example 4.

[0086] To further illustrate the technological advancements of this invention, experimental tests were conducted on the indicators of different embodiments and comparative examples.

[0087] Flame retardant performance testing of materials: The LOI values ​​of different resins in the optical resin lens materials of Examples 1-5 and Comparative Examples 1-2 were tested according to GB / T2406.2-2009. The above test data are listed in Table 1.

[0088] Optical performance testing: The transmittance (transmission ratio) and YI value of the optical resin lens materials of Examples 1-5 and Comparative Examples 1-2 were tested respectively, and the test data are listed in Table 1.

[0089] Thermal performance testing: The glass transition temperature (Tg) of the optical resin lens materials of Examples 1-5 and Comparative Examples 1-2 was tested using differential scanning calorimetry (DSC). Each sample was tested in triplicate, and the average value was taken. The Tg test data of the samples are shown in Table 1.

[0090] Table 1. Test values ​​of optical resin lens materials in Examples 1-5 and Comparative Examples 1-2

[0091]

[0092] As can be seen from the results of Examples 1-5 and Comparative Examples 1-2, the high heat-resistant and flame-retardant polyurethane optical resin obtained by the preparation method of the present invention not only has a high LOI value and Tg, but its optical properties are also not negatively affected. Therefore, according to the preparation method of the present invention, a high heat-resistant and flame-retardant polyurethane resin with excellent performance can be prepared.

[0093] The embodiments described above are some, but not all, embodiments of the present invention. Those skilled in the art, guided by this specification, can make modifications or adjustments to the present invention. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A method for preparing a high heat-resistant and flame-retardant polyurethane resin, characterized in that, The flame retardant polymer is prepared by mixing isocyanate components, polythiols, flame retardant polymers, optional catalysts, optional release agents, and optional UV absorbers and then carrying out a polymerization reaction. The flame retardant polymer is copolymerized by tetrabromobisphenol A dielyl ether monomer and 2-vinyl-4,6-diamino-1,3,5-triazine monomer. The amount of the flame-retardant polymer added is 0.1%~10wt%. The molar ratio of tetrabromobisphenol A dielyl ether monomer to 2-vinyl-4,6-diamino-1,3,5-triazine monomer is 1:1 to 20:

1.

2. The preparation method according to claim 1, characterized in that, The flame-retardant polymer is prepared by dissolving tetrabromobisphenol A dielyl ether monomer and 2-vinyl-4,6-diamino-1,3,5-triazine monomer in an organic solvent, and then carrying out free radical polymerization under the conditions of a free radical initiator.

3. The preparation method according to claim 1, characterized in that, The molar ratio of tetrabromobisphenol A dielyl ether monomer to 2-vinyl-4,6-diamino-1,3,5-triazine monomer is 3:1 to 15:

1.

4. The preparation method according to claim 3, characterized in that, The molar ratio of tetrabromobisphenol A dielyl ether monomer to 2-vinyl-4,6-diamino-1,3,5-triazine monomer is 5:1-10:

1.

5. The preparation method according to claim 2, characterized in that, The free radical initiator is an organic peroxide compound initiator, an azo compound initiator, a redox system initiator, or a photosensitizer.

6. The preparation method according to claim 5, characterized in that, The organic peroxide initiator is selected from benzoyl peroxide or dicarbonate peroxide; the azo compound initiator is selected from azobisisobutyronitrile or azobisisoheptanenitrile; the redox system initiator is selected from an organic oil-soluble redox system formed by peroxide acyl compounds and tertiary amine compounds; and the photoinitiator is selected from photoinitiator IRGACURE-2959.

7. The preparation method according to claim 2, characterized in that, The amount of the free radical initiator added is 1%-6% of the total weight of tetrabromobisphenol A dielyl ether (TBPA) monomer and 2-vinyl-4,6-diamino-1,3,5-triazine (VDT) monomer.

8. The preparation method according to claim 6, characterized in that, The free radical initiator is a composite initiator of benzoyl peroxide and N,N-dimethylaniline, and the amount of both added is 1%-3% of the total weight of TBPA monomer and VDT monomer.

9. The preparation method according to claim 8, characterized in that, The free radical initiator is a composite initiator of benzoyl peroxide and N,N-dimethylaniline, and the amount of both added is 1.5-2.5% of the total weight of TBPA monomer and VDT monomer.

10. The preparation method according to claim 1, characterized in that, The reaction temperature for preparing the flame-retardant polymer is 0℃~50℃, and the reaction time is 1~12h.

11. The preparation method according to claim 2, characterized in that, The organic solvent includes one or more of the following: halogenated hydrocarbons, ketones, ethers, alcohols, amides, and sulfones.

12. The preparation method according to claim 11, characterized in that, The organic solvent is dimethyl sulfoxide.

13. The preparation method according to claim 1, characterized in that, The isocyanate component is selected from aliphatic, alicyclic, or aromatic isocyanates.

14. The preparation method according to claim 13, characterized in that, The isocyanate component is selected from one or more combinations of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, naphthalene diisocyanate, dimethylbiphenyl diisocyanate, 1,4-cyclohexane diisocyanate, terephthalic diisocyanate, tetramethyl isophthalic diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, phenyl diisocyanate, cyclohexane diisocyanate, and norbornene diisocyanate.

15. The preparation method according to claim 14, characterized in that, The isocyanate component is selected from phenyl dimethyl diisocyanate or cyclohexane dimethyl diisocyanate.

16. The preparation method according to claim 15, characterized in that, The isocyanate component is selected from phenyl diisocyanate.

17. The preparation method according to claim 1, characterized in that, The polythiol compound is selected from one or more of the following: ethylene glycol dimercaptoacetate, 1,2-bis(2-mercaptoethoxy)ethane, di(mercaptoacetic acid)-1,4-butanediol, trimethylolpropane tris(3-mercaptopropionate), trimethylolpropane tris(2-mercaptoacetate), pentaerythritol tetramercaptoacetate, 2,3-dithio(2-mercapto)-1-propanethiol, and pentaerythritol tetra(3-mercaptopropionic acid).

18. The preparation method according to claim 17, characterized in that, The polythiol compound is selected from 2,3-dithio(2-mercapto)-1-propanethiol or pentaerythritol tetrakis(3-mercaptopropionic acid) ester.

19. The preparation method according to claim 18, characterized in that, The polythiol compound is 2,3-dithio(2-mercapto)-1-propanethiol.

20. The preparation method according to claim 1, characterized in that, The isocyanate component and the polythiol compound are used in an NCO-based / SH-based molar ratio of 0.8-1.

5.

21. The preparation method according to claim 20, characterized in that, The isocyanate component and the polythiol compound are used in an NCO-based / SH-based molar ratio of 0.9-1.

1.

22. The preparation method according to claim 1, characterized in that, The amount of the flame-retardant polymer added is 0.5% to 8 wt%, based on the total mass of the isocyanate component and the polythiol compound.

23. The preparation method according to claim 22, characterized in that, The amount of the flame-retardant polymer added is 1% to 6 wt%.

24. The preparation method according to claim 1, characterized in that, The catalyst is an organotin compound.

25. The preparation method according to claim 24, characterized in that, The amount of catalyst added is 0.001 to 2.0% by weight, based on the total mass of the isocyanate component and polythiol compound.

26. The preparation method according to claim 25, characterized in that, The amount of catalyst added is 0.005 to 1.0% by weight, based on the total mass of the isocyanate component and polythiol compound.

27. The preparation method according to claim 1, characterized in that, The ultraviolet absorber is a benzophenone, triazine, or benzotriazole ultraviolet absorber, and the amount added is 0.001-2.0% by weight, based on the total mass of the isocyanate component and polythiol compound.

28. The preparation method according to claim 27, characterized in that, The amount of the UV absorber added is from 0.01 to 1.0% by weight, based on the total mass of the isocyanate component and the polythiol compound.

29. The preparation method according to claim 1, characterized in that, The release agent is a phosphate ester-based release agent, and the addition amount is 0.01-3.0% by weight, based on the total mass of the isocyanate component and polythiol compound.

30. The preparation method according to claim 29, characterized in that, The amount of the release agent added is from 0.05 to 2.0% by weight, based on the total mass of the isocyanate component and the polythiol compound.

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