Preparation method of anti-yellowing high-stability bio-based 1, 5-pentamethylene diisocyanate product

Abstract

The invention relates to a preparation method of a bio-based 1, 5-pentamethylene diisocyanate product with yellowing resistance and high stability. A synergistic composite stable system composed of an efficient main antioxidant, an auxiliary antioxidant and a plurality of ultraviolet absorbents / light stabilizers in a scientific proportion is constructed. Wherein the main antioxidant is mainly used for capturing free radicals and blocking an oxidation chain reaction; the auxiliary antioxidant decomposes hydroperoxide to inhibit the hydroperoxide from further initiating the degradation of the material; the ultraviolet stabilizer effectively delays the color change process caused by illumination by absorbing or quenching excited state energy. The preparation method disclosed by the invention has the advantages of high process compatibility, easiness in acquisition of auxiliaries, simple compounding and post-treatment steps and convenience in large-scale popularization; the environmental protection property is outstanding, the yellowing resistance and the storage stability of the product are greatly improved, the normal-temperature closed storage period is prolonged to 6 months or above, the NCO content retention rate is greater than or equal to 96%, and the storage and transportation cost is reduced; the influence of thermal oxidation and photodegradation is resisted, and a complex application environment is adapted.

Description

Technical Field

[0001] This invention belongs to the field of advanced chemical new materials, specifically relating to the preparation and performance optimization of bio-based isocyanates, and particularly to a method for preparing and applying a yellowing-resistant, highly stable bio-based 1,5-pentanediisocyanate product. Background Technology

[0002] With the increasing global awareness of environmental protection and the advancement of sustainable development strategies, bio-based materials are becoming an inevitable trend in the industry to replace traditional petroleum-based materials. Bio-based 1,5-pentanediisocyanate, as a core monomer in polyurethane synthesis, has advantages such as environmental friendliness and low carbon footprint due to its raw material source being renewable biomass resources, and is gradually becoming an ideal alternative to petroleum-based isocyanates.

[0003] However, existing bio-based 1,5-pentanediisocyanate products face multiple technical challenges in practical applications: First, they exhibit poor resistance to yellowing. Under ultraviolet irradiation or high-temperature environments, the molecular structure is prone to photo-oxidation and thermal aging reactions, leading to a darkening of the product's color and severe damage to the appearance quality of the final product. Existing single ultraviolet absorbers or antioxidants are insufficient to simultaneously block multiple yellowing pathways, and the color difference ΔE generally exceeds 3.0 after 50 hours of ultraviolet aging. Second, they suffer from insufficient storage stability. Affected by residual impurities and molecular activity, the product is prone to self-polymerization and oxidation reactions. Firstly, after 3 months of storage at room temperature, the NCO content retention rate drops below 85%, requiring refrigerated transportation and storage, which significantly increases application costs. Secondly, it has poor adaptability to extreme environments, easily degrading at high temperatures and crystallizing at low temperatures, limiting its application in complex working conditions. Thirdly, existing improvement solutions have limitations. For example, patent CN118185125A only focuses on UV protection and does not solve the problem of thermal oxidation and yellowing. Patent CN101503595B's composite antioxidant system lacks a targeted UV protection design, resulting in limited improvement in weather resistance.

[0004] Therefore, developing a bio-based method for preparing 1,5-pentanediisocyanate that can simultaneously address issues of yellowing, storage stability, and adaptability to extreme environments is crucial for promoting its large-scale application. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of existing bio-based 1,5-pentanediisocyanate products, such as poor resistance to yellowing, short storage period, and weak adaptability to extreme environments, and to provide a preparation method that is simple, highly compatible, and has excellent performance.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing a yellowing-resistant, highly stable bio-based 1,5-pentanediisocyanate, characterized by comprising three steps: raw material pretreatment, synergistic stabilization system compounding, and finished product post-treatment, as detailed below: Step 1, raw material pretreatment: Select bio-based 1,5-pentanediisocyanate monomers with a purity ≥99.95%, hydrolyzed chlorine content 60~90 ppm, solvent residue 0.2~0.4%, and acidity 60~75 ppm as starting materials; The precursor for preparing the bio-based 1,5-pentanediisocyanate monomer is 1,5-pentanediamine derived from renewable biomass resources; the renewable biomass resources include non-directly edible materials, including one or more of corn starch, sugarcane bagasse, lignin or straw. Step 2, synergistic stabilization system compounding: Add compounding auxiliaries to 1,5-pentanediisocyanate monomer, with a total addition amount of 0.2%~2% of the mass of 1,5-pentanediisocyanate monomer. The compounding process is carried out at 25~30 ℃ under a nitrogen protective atmosphere, with a stirring speed of 300~500 r / min and a stirring time of 30~60 minutes. The compound additives include a combination of antioxidants and a combination of UV stabilizers. The antioxidant combination is any of the following: Option A. Antioxidant 1010 and Antioxidant 168 are compounded at a mass ratio of 1:2 to 2:1; Option B. Antioxidant 1010 and Antioxidant 330 are compounded at a mass ratio of 4:1 to 1:6; Option C. Antioxidant 1076 and Antioxidant 168 are compounded at a mass ratio of 3:1 to 5:1; Option D. Antioxidant 1098 and antioxidant 626 are compounded at a mass ratio of 5:1 to 1:5; The UV stabilizer combination is any of the following: Option I. UV-P and surface-modified nano-zinc oxide are compounded at a mass ratio of 2:1 to 3:1; Option II. UV-P and nano-titanium dioxide are compounded at a mass ratio of 3:1 to 4:1; Option III. UV-327 and nano zinc oxide are compounded at a mass ratio of 2.5:1 to 3.5:1; Option IV. UV-326 and nano-titanium dioxide are compounded at a mass ratio of 3:1 to 3.8:1; Step 3, post-processing of finished product: In a light-proof environment with relative humidity ≤30%, after nitrogen purging, seal and store the product. The ambient temperature should be controlled at 10~30 ℃, and direct sunlight and violent vibration should be avoided.

[0007] The nitrogen purging operation is as follows: Nitrogen gas with a purity of ≥99.99% is introduced into the storage container, and the purging is carried out 3 times. The pressure of each purging is 0.12~0.15MPa, and the pressure is maintained for 1~15 minutes. Finally, the oxygen content in the container is ≤0.05% and the moisture content is ≤0.03%. The container is sealed and stored in a stainless steel container with a brown polytetrafluoroethylene lining.

[0008] Furthermore, in step one, the precursor 1,5-pentanediamine for the preparation of the bio-based 1,5-pentanedicyanate monomer is obtained from renewable biomass resources through fermentation, separation and purification, and the purity of 1,5-pentanediamine is ≥99.95%.

[0009] In step two, the mass ratio of the antioxidant combination to the UV stabilizer combination is 1:1 to 3:1.

[0010] In step two, the surface-modified nano zinc oxide is a hydrophobic nanoparticle modified with a silane coupling agent, which is γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane or γ-methacryloyloxypropyltrimethoxysilane. The amount of silane coupling agent added is 2% to 3% of the mass of nano zinc oxide, the dispersed particle size of nano zinc oxide is 30 to 40 nm, and the dispersion uniformity in the 1,5-pentanediisocyanate system is ≥90%.

[0011] In step two, the nano-titanium dioxide is anatase type, with a purity ≥99.5%, a particle size ≤30 nm, and a particle dispersion ≥95%.

[0012] In step two, the total amount of the compounding additives added is 0.25% to 0.35% of the mass of 1,5-pentanediisocyanate monomer.

[0013] In step two, the stirring process employs ultrasonic-assisted dispersion with an ultrasonic power of 100-150 W and an ultrasonic time of 10-50 minutes to further improve the uniformity of the additive dispersion.

[0014] The bio-based 1,5-pentanediisocyanate product obtained by the preparation method is characterized in that the product meets the following performance indicators: (1) After being stored in a sealed container at room temperature (25±2 ℃) for 6 months, the NCO content retention rate was ≥96%; (2) Artificial accelerated UV aging (0.68 W / m 2 After 120 hours (at 340 nm), no significant change in color was observed to the naked eye. (3) After being placed at a constant temperature of 160 ℃ for 8 hours, no significant change in color was observed by the naked eye; (4) Stored at -10~30±2 ℃ for 30 days, no crystals precipitate; (5) The viscosity at 25 ℃ is 800~1200 mPa·s, and the viscosity fluctuation range is ≤±5%; (6) It is a colorless and transparent liquid with no visible impurities.

[0015] The application of the bio-based 1,5-pentanediisocyanate product is characterized in that the product is used in high-end coatings, elastomers, adhesives, or rocket propellants; the elastomers include medical elastomers and elastic components of sports equipment; the adhesives include high-end composite adhesives and electronic component encapsulation adhesives.

[0016] The beneficial effects of this invention are: strong process compatibility, readily available additives, simple compounding and post-processing steps, seamless integration with existing 1,5-pentanediisocyanate production processes, facilitating large-scale promotion; outstanding environmental friendliness, with raw materials derived from renewable biomass resources, low additive dosage and environmentally friendly, meeting environmental regulations; significantly improved yellowing resistance, with no significant color change observed after 120 hours of artificially accelerated UV aging, and no significant yellowing after 6 months of room temperature storage, fully covering both heat and light usage scenarios; significantly improved storage stability, with a room temperature sealed storage period extended to over 6 months, NCO content retention rate ≥96%, requiring no special storage conditions, reducing warehousing and transportation costs; resistant to thermal oxidation and photodegradation, with no significant color change observed after 8 hours at 160℃, and no crystallization after 30 days of storage at -10~30℃, adaptable to complex application environments. Attached Figure Description

[0017] Figure 1 The image shown is a gas chromatography-mass spectrometry (GC-MS) chromatogram of the 1,5-pentanediisocyanate product involved in Example 1 of the present invention after being stored for 6 months. Figure 2 The image shows the Fourier transform infrared absorption (FT-IR) spectrum of the 1,5-pentanediisocyanate product involved in Example 1 of the present invention after being stored for 6 months. Figure 3 The image shows the solid-state nuclear magnetic resonance (1H NMR) spectrum of the 1,5-pentanediisocyanate product involved in Example 1 of the present invention after UV aging for 120 hours. Figure 4 The image shown is an optical photograph of the 1,5-pentanediisocyanate product involved in Example 1 of the present invention after being stored for 6 months, subjected to ultraviolet aging for 120 hours, and subjected to high-temperature treatment at 160 °C for 8 hours. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto. The raw material 1,5-pentanediisocyanate used in the embodiments was independently developed and industrially produced by Polysilicon Company. All additives are commercially available conventional products. The required performance testing methods are as follows: NCO content was determined according to GB / T 12009.4-2016 standard; Viscosity was measured using a rotational viscometer according to GB / T 10247-2008 standard.

[0019] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto. Example 1

[0020] A method for preparing a yellowing-resistant, highly stable bio-based 1,5-pentanediisocyanate product, comprising the following steps: (1) Raw material preparation: Bio-based 1,5-pentanediisocyanate monomer with a purity of 99.95% (hydrolyzed chlorine 85 ppm, solvent content 0.3%, acidity 70 ppm) was selected, and its precursor PDA was derived from corn starch; antioxidant 1010, antioxidant 168; UV-P, nano zinc oxide (particle size 40 nm, modified by γ-aminopropyltriethoxysilane, modifier addition amount 2.5%). (2) Additive compounding: Add 1.5 g antioxidant 1010, 1 g antioxidant 168 (antioxidant combination scheme A, mass ratio 1.5:1), 1 g UV-P and 0.5 g nano zinc oxide (UV stabilizer combination scheme I, mass ratio 2:1) to 1 kg 1,5-pentanediisocyanate monomer, the total amount of compounded additives added is 4 g (accounting for 0.4% of the mass of 1,5-pentanediisocyanate); stir at 400 r / min for 45 minutes at 28 ℃ under nitrogen protection, and simultaneously use 120 W ultrasonic assisted dispersion for 12 minutes; (3) Post-treatment: In a light-proof environment with a relative humidity of 25%, 99.99% pure nitrogen gas is introduced into a brown polytetrafluoroethylene-lined stainless steel container and replaced 3 times (each time at a pressure of 0.12 MPa and held for 10 minutes). After sealing, it is stored at 25 ℃ for 6 months. Performance testing: 100% NCO content retention after 6 months of storage at room temperature; no significant color change after 120 hours of UV aging; no significant color change after 8 hours of high-temperature treatment at 160 ℃; no crystallization after 30 days of storage at -5 ℃; viscosity of 6 mPa・s at 25 ℃.

[0021] Example 2

[0022] A method for preparing a yellowing-resistant, highly stable bio-based 1,5-pentanediisocyanate product, comprising the following steps: (1) Raw material preparation: Bio-based 1,5-pentanediisocyanate monomer with a purity of 99.95% (hydrolyzed chlorine 85 ppm, solvent content 0.3%, acidity 70 ppm) was selected, and its precursor PDA was derived from corn starch; antioxidant 1010, antioxidant 330; UV-P, nano titanium dioxide (anatase type, purity 99.6%, particle size 25 nm).

[0023] (2) Additive compounding: Add 1.8 g antioxidant 1010, 1.2 g antioxidant 330 (antioxidant combination scheme B, mass ratio 1.5:1), 1.2 g UV-P and 0.4 g nano titanium dioxide (UV stabilizer combination scheme II, mass ratio 3:1) to 1 kg 1,5-pentanediisocyanate monomer, the total amount of compounded additives added is 4.6 g (accounting for 0.46% of PDI mass); stir at 350 r / min for 50 minutes under nitrogen protection at 26 ℃, and then disperse ultrasonically for 15 minutes (power 100 W).

[0024] (3) Post-treatment: The nitrogen replacement parameters are 0.13 MPa pressure, pressure held for 12 minutes, and the rest are the same as in Example 1.

[0025] Performance testing: Viscosity at 25 °C was 12 mPa·s, and the rest was the same as in Example 1.

[0026] Example 3 A method for preparing a yellowing-resistant, highly stable bio-based 1,5-pentanediisocyanate product, comprising the following steps: (1) Raw material preparation: Bio-based 1,5-pentanediisocyanate monomer with a purity of 99.95% (hydrolyzed chlorine 70 ppm, solvent content 0.25%, acidity 65 ppm) was selected. The precursor PDA was derived from sugarcane bagasse; antioxidant 1076, antioxidant 168; UV-327, nano zinc oxide (particle size 35nm, modified by γ-glycidoxypropyltrimethoxysilane, modifier addition amount 2%, dispersion uniformity 96%).

[0027] (2) Compounding of adjuvants: 1.5 g of antioxidant 1076, 1 g of antioxidant 168 (antioxidant combination scheme C, mass ratio 1.5:1), 1.05 g of UV-327 and 0.35 g of nano zinc oxide (UV stabilizer combination scheme III, mass ratio 3:1) were added to 1 kg of 1,5-pentanediisocyanate monomer. The total amount of compounded adjuvants added was 3.9 g (accounting for 0.39% of the mass of 1,5-pentanediisocyanate). The mixture was stirred at 450 r / min for 35 minutes under nitrogen protection at 30℃, and ultrasonically dispersed for 10 minutes (power 150W).

[0028] (3) Post-processing: Same as in Example 1.

[0029] Performance testing: After 6 months of storage at room temperature, the NCO content retention rate was 98%; after 8 hours of high temperature at 160 ℃, the NCO content decreased by 1.7%, and the rest was the same as in Example 1.

[0030] Example 4 A method for preparing a yellowing-resistant, highly stable bio-based 1,5-pentanediisocyanate product, comprising the following steps: (1) Raw material preparation: Same as in Example 3; (2) Additive compounding: 1.2 g antioxidant 1098, 1.2 g antioxidant 626 (antioxidant combination scheme D, mass ratio 1:1), 1.14 g UV-326 and 0.38 g nano titanium dioxide (UV stabilizer combination scheme IV, mass ratio 3:1) were added to 1 kg 1,5-pentanediisocyanate monomer. The total amount of compounded additives added was 0.392 g (accounting for 0.392% of the mass of 1,5-pentanediisocyanate). The mixture was stirred at 380 r / min for 40 minutes under nitrogen protection at 27 ℃, and ultrasonically dispersed for 13 minutes (power 130W).

[0031] (3) Post-treatment: Nitrogen replacement pressure 0.15MPa, pressure held for 11 minutes, the rest is the same as in Example 1.

[0032] Performance testing: NCO content retention rate was 97.5% after 6 months of storage at room temperature; NCO content decreased by 1.3% after 8 hours of high temperature at 160 ℃; no crystallization was observed after 30 days of storage at -10 ℃; viscosity was 9 mPa・s at 25 ℃.

[0033] Example 5 A method for preparing a yellowing-resistant, highly stable bio-based 1,5-pentanediisocyanate product, comprising the following steps: (1) Raw material preparation: Bio-based 1,5-pentanediisocyanate monomer with a purity of 99.95% (hydrolyzed chlorine 60 ppm, solvent content 0.2%, acidity 60 ppm) was selected. The precursor PDA was derived from lignin; antioxidant 1010, antioxidant 168; UV-P, nano zinc oxide (particle size 30 nm, modified by γ-methacryloyloxypropyltrimethoxysilane, modifier addition amount 3%).

[0034] (2) Additive compounding: Add 2 g of antioxidant 1010, 1 g of antioxidant 168 (antioxidant combination scheme A, mass ratio 2:1), 0.9 g of UV-P and 0.3 kg of nano zinc oxide (UV stabilizer combination scheme I, mass ratio 3:1) to 1 kg of 1,5-pentanediisocyanate monomer. The total amount of compounded additives added is 4.2 g (accounting for 0.42% of the mass of 1,5-pentanediisocyanate). Stir at 450 r / min for 45 minutes under nitrogen protection at 29 ℃, and then disperse ultrasonically for 15 minutes (power 140 W).

[0035] (3) Post-treatment: Nitrogen replacement pressure 0.15 MPa, pressure held for 15 minutes, final oxygen content 0.04%, moisture content 0.02%, the rest is the same as in Example 1.

[0036] Performance testing: 99% NCO content retention rate after 6 months of storage at room temperature; no color difference after 120 hours of UV aging; NCO content decreased by 1.6% after 8 hours of high temperature at 180℃.

[0037] Example 6 A method for preparing a yellowing-resistant, highly stable bio-based 1,5-pentanediisocyanate product, comprising the following steps: (1) Raw material preparation: Same as in Example 5; antioxidant 1076, antioxidant 168; UV-P, nano titanium dioxide (anatase type, purity 99.7%, particle size 22 nm).

[0038] (2) Additive compounding: Add 2.5 g of antioxidant 1076, 1 g of antioxidant 168 (antioxidant combination scheme C, mass ratio 2.5:1), 1.2 g of UV-P and 0.3 g of nano titanium dioxide (UV stabilizer combination scheme II, mass ratio 4:1) to 1 kg of 1,5-pentanediisocyanate monomer, and the total amount of compounded additives added is 3.5 g (accounting for 0.35% of the mass of 1,5-pentanediisocyanate); stir at 360 r / min for 60 minutes at 25℃ under nitrogen protection, and then disperse ultrasonically for 20 minutes (power 110W).

[0039] (3) Post-treatment: Nitrogen replacement pressure 0.14 MPa, pressure held for 15 minutes, the rest is the same as in Example 1.

[0040] Performance testing: After 6 months of storage at room temperature, the NCO content retention rate was 97.3%; after 8 hours of high temperature at 160 ℃, the NCO content decreased by 1.4%.

[0041] Explanation of the attached image: Figure 1The image shows the gas chromatography-mass spectrometry (GC-MS) spectrum of the 1,5-pentanediisocyanate product after 6 months of storage. In electron impact (EI) ionization mode, due to the tendency for molecular ion fragmentation, no significant strong molecular ion peak was observed in the spectrum, despite the theoretical relative molecular mass of 1,5-pentanediisocyanate being 154. However, a characteristic peak at m / z = 42 was observed, caused by the [NCO]⁺ ion generated from the fragmentation of the isocyanate group (-NCO), which can serve as an auxiliary basis for functional group identification. Furthermore, a series of fragment ions were detected, including m / z = 56 (presumably alkyl fragments containing oxides or nitrogen) and m / z = 43 (such as C3H7⁺), which are attributed to the cleavage of straight-chain alkyl groups containing 5 carbon atoms. The formation of peaks at m / z = 82, 99, and 109 is the result of the synergistic effect of the carbon chain and isocyanate group during further fragmentation of the molecular ion. The measured spectrum was compared with the standard mass spectrum of 1,5-pentanediisocyanate, and the peak positions and relative intensities showed good consistency, confirming that the sample component was 1,5-pentanediisocyanate.

[0042] Figure 2 The image shows the Fourier transform infrared (FT-IR) absorption spectrum of the 1,5-pentanediisocyanate product involved in Example 1 of this invention after 6 months of storage. FT-IR analysis reveals characteristic absorption peaks for specific functional groups: the -CH2- group has peaks in the range of 3000–2750 cm⁻¹. -1 and 1250 cm -1 Absorption peaks appear nearby, corresponding to the stretching and bending vibrations of the methylene group, respectively; while the -N=C=O group shows an absorption peak at 2250 cm⁻¹. -1 The surrounding area exhibits a strong characteristic absorption peak, which is a typical spectral feature of -NCO. Meanwhile, intensity analysis showed that the intensity of -N=C=O in the 1,5-pentanediisocyanate product remained unchanged after 6 months.

[0043] Figure 3The image shows the solid-state nuclear magnetic resonance (¹H NMR) spectrum of the 1,5-pentanediisocyanate product involved in Example 1 of this invention after UV aging for 120 hours. In the ¹H NMR spectrum of the 1,5-pentanediisocyanate sample, the chemical shift represented by the horizontal axis reflects the electron cloud density around the atomic nucleus and its chemical environment. Atomic nuclei in different functional groups have specific chemical shift ranges: the chemical shifts of saturated alkyl carbons are typically between 0 and 60 ppm, with the signal peak appearing at approximately 30 ppm likely originating from the methylene carbon in the alkyl chain. When the methylene group acts as an electron-donating group, it increases the electron cloud density of the double-bonded carbon atoms, thereby enhancing its shielding effect and causing the chemical shift to shift towards a higher field (i.e., a decrease in value). Therefore, the carbon signal of the C=N bond typically appears in the range of approximately 150–160 ppm, while the carbon signal of the C=O bond appears between 150 and 220 ppm. The chemical shifts and intensities of each peak in the spectrum are consistent with the structural characteristics of fresh 1,5-pentanediisocyanate, and the intensities remain unchanged.

[0044] Figure 4 The image shown is an optical photograph of the 1,5-pentanediisocyanate product involved in Example 1 of this invention after 6 months of storage, 120 hours of ultraviolet aging, and 8 hours of high-temperature treatment at 160°C. It can be clearly observed that, compared with the fresh sample, the sample after 6 months of storage, the sample after 120 hours of ultraviolet aging, and the sample after 8 hours of high-temperature treatment at 160°C all appear as colorless and transparent liquids, and there are no impurities visible to the naked eye.

Claims

1. A method for preparing a bio-based 1,5-pentanediisocyanate with high stability and resistance to yellowing, characterized in that, It includes three steps: raw material pretreatment, synergistic stabilization system compounding, and finished product post-processing, as detailed below: Step 1, raw material pretreatment: Select bio-based 1,5-pentanediisocyanate monomers with a purity ≥99.95%, hydrolyzed chlorine content 60~90 ppm, solvent residue 0.2~0.4%, and acidity 60~75 ppm as starting materials; Step 2, synergistic stabilization system compounding: Add compounding auxiliaries to 1,5-pentanediisocyanate monomer, with a total addition amount of 0.2%~2% of the mass of 1,5-pentanediisocyanate monomer. The compounding process is carried out at 25~30 ℃ under a nitrogen protective atmosphere, with a stirring speed of 300~500 r / min and a stirring time of 30~60 minutes. Step 3, post-processing of finished product: In a light-proof environment with relative humidity ≤30%, after nitrogen purging, seal and store the product. The ambient temperature should be controlled at 10~30 ℃, and direct sunlight and violent vibration should be avoided.

2. The method for preparing the yellowing-resistant, highly stable bio-based 1,5-pentanediisocyanate according to claim 1, characterized in that, In step one, the precursor for preparing the bio-based 1,5-pentanediisocyanate monomer is 1,5-pentanediamine derived from renewable biomass resources; the renewable biomass resources include non-directly edible materials, including one or more of corn starch, sugarcane bagasse, lignin or straw. In step two, the compound additives include a combination of antioxidants and a combination of UV stabilizers. The antioxidant combination is any of the following: Option A. Antioxidant 1010 and Antioxidant 168 are compounded at a mass ratio of 1:2 to 2:1; Option B. Antioxidant 1010 and Antioxidant 330 are compounded at a mass ratio of 4:1 to 1:6; Option C. Antioxidant 1076 and Antioxidant 168 are compounded at a mass ratio of 3:1 to 5:1; Option D. Antioxidant 1098 and antioxidant 626 are compounded at a mass ratio of 5:1 to 1:5; The UV stabilizer combination is any of the following: Option I. UV-P and surface-modified nano-zinc oxide are compounded at a mass ratio of 2:1 to 3:1; Option II. UV-P and nano-titanium dioxide are compounded at a mass ratio of 3:1 to 4:1; Option III. UV-327 and nano zinc oxide are compounded at a mass ratio of 2.5:1 to 3.5:1; Option IV. UV-326 and nano-titanium dioxide are compounded at a mass ratio of 3:1 to 3.8:1; In step three, the nitrogen purging operation is as follows: nitrogen gas with a purity of ≥99.99% is introduced into the storage container, purging 3 times, with a purging pressure of 0.12~0.15MPa each time, and the pressure is maintained for 1~15 minutes. Finally, the oxygen content in the container is ≤0.05% and the moisture content is ≤0.03%. The container is sealed and stored in a stainless steel container with a brown polytetrafluoroethylene lining.

3. The method for preparing the yellowing-resistant, highly stable bio-based 1,5-pentanediisocyanate according to claim 2, characterized in that, In step one, the precursor 1,5-pentanediamine, which is the preparation precursor of the bio-based 1,5-pentanediisocyanate monomer, is obtained from renewable biomass resources through fermentation, separation and purification, and the purity of 1,5-pentanediamine is ≥99.95%.

4. The method for preparing the yellowing-resistant, highly stable bio-based 1,5-pentanediisocyanate according to claim 2, characterized in that, In step two, the mass ratio of the antioxidant combination to the UV stabilizer combination is 1:1 to 3:

1.

5. The method for preparing the yellowing-resistant, highly stable bio-based 1,5-pentanediisocyanate according to claim 2, characterized in that, In step two, the surface-modified nano zinc oxide is a hydrophobic nanoparticle modified with a silane coupling agent, which is γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane or γ-methacryloyloxypropyltrimethoxysilane. The amount of silane coupling agent added is 2% to 3% of the mass of nano zinc oxide, the dispersed particle size of nano zinc oxide is 30 to 40 nm, and the dispersion uniformity in the 1,5-pentanediisocyanate system is ≥90%.

6. The method for preparing the yellowing-resistant, highly stable bio-based 1,5-pentanediisocyanate according to claim 2, characterized in that, In step two, the nano-titanium dioxide is anatase type, with a purity ≥99.5%, a particle size ≤30 nm, and a particle dispersion ≥95%.

7. The method for preparing the yellowing-resistant, highly stable bio-based 1,5-pentanediisocyanate according to claim 1, characterized in that, In step two, the total amount of the compounding additives added is 0.25% to 0.35% of the mass of 1,5-pentanediisocyanate monomer.

8. The method for preparing the yellowing-resistant, highly stable bio-based 1,5-pentanediisocyanate according to claim 1, characterized in that, The stirring process described in step two uses ultrasonic-assisted dispersion with an ultrasonic power of 100-150 W and an ultrasonic time of 10-50 minutes to further improve the uniformity of the additive dispersion.

9. The bio-based 1,5-pentanediisocyanate product obtained by any one of the preparation methods according to claims 1–8, characterized in that, The product meets the following performance indicators: (1) After being stored in a sealed container at room temperature (25±2 ℃) for 6 months, the NCO content retention rate was ≥96%; (2) Artificial accelerated ultraviolet aging (0.68 W / m 2 After 120 hours (at 340 nm), no significant change in color was observed to the naked eye. (3) After being placed at a constant temperature of 160 ℃ for 8 hours, no significant change in color was observed by the naked eye; (4) Stored at -10~30±2 ℃ for 30 days, no crystals precipitate; (5) The viscosity at 25 ℃ is 800~1200 mPa·s, and the viscosity fluctuation range is ≤±5%; (6) It is a colorless and transparent liquid with no visible impurities.

10. The application of the bio-based 1,5-pentanediisocyanate product according to claim 9, characterized in that, The product is used in high-end coatings, elastomers, adhesives, or rocket propellants; the elastomers include medical elastomers and elastic components for sports equipment; the adhesives include high-end composite adhesives and electronic component encapsulation adhesives.

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