A low cost modified polyurethane resin and a method for its preparation

Abstract

This invention discloses a low-cost modified polyurethane resin, composed of a two-component polyurethane resin system including a white component and a black component. Addressing the technical shortcomings of existing polyurethane pultrusion resins, such as high cost, high water sensitivity, short operating time, and insufficient mechanical properties, this invention provides a low-cost modified polyurethane resin and its preparation method. By optimizing the raw material ratio and preparation process of the two-component system, this invention significantly improves the mechanical properties, glass transition temperature, and surface hardness of the resin while reducing raw material costs by 10%-20%. Simultaneously, it achieves low water sensitivity and a long operating time at room temperature. Furthermore, the system is solvent-free and VOC-free, exhibiting excellent environmental friendliness, and is suitable for open-tank pultrusion and winding processes.

Description

Technical Field

[0001] This invention relates to the field of polyurethane resin materials technology, and specifically to a low-cost modified polyurethane resin and its preparation method. Background Technology

[0002] Polyurethane resins, due to their excellent mechanical properties, corrosion resistance, and molding processability, are widely used in composite material molding processes such as pultrusion and filament winding, serving as the core matrix material for products such as wind turbine beams, fiberglass pipes, and profiles. Traditional polyurethane pultrusion resins often employ a polyether polyol-isocyanate binary system, which suffers from several technical drawbacks: First, the large amount of isocyanate used leads to high raw material costs, hindering the widespread application of polyurethane composites in the low-to-mid-end market; second, the system is highly sensitive to moisture, requiring strict control of a low-humidity environment during molding, increasing the operational difficulty and environmental control costs; third, the short operating time at room temperature (typically 15-25 minutes) results in low process tolerance and a tendency for product molding defects; fourth, the low crosslinking density after curing, coupled with insufficient glass transition temperature (Tg) and surface hardness, limits its application in high-temperature and high-hardness environments.

[0003] Meanwhile, traditional polyurethane pultrusion resins also face bottlenecks in improving mechanical properties. The tensile and flexural strengths of pure resins are insufficient to meet the performance requirements of high-end composite materials, and some fields still rely on epoxy resins. However, epoxy resins suffer from long curing times, high brittleness, and high costs. In addition, some polyurethane resin systems add organic solvents to improve processability, resulting in VOC emissions, which do not comply with current environmental protection policies.

[0004] To address these issues, the industry has attempted to optimize polyurethane resin performance by adding modified monomers and adjusting polyol ratios. However, these methods often suffer from difficulties in balancing performance and cost, as well as poor process compatibility. For example, while some modified systems reduced isocyanate usage, their mechanical properties significantly decreased; others extended the operating time, but water sensitivity remained unimproved, making them unsuitable for pultrusion and winding processes in open glue baths. Therefore, developing a low-cost, low-water-sensitivity, long-operating-time, and mechanically superior modified polyurethane resin has become a pressing technical challenge in the field of polyurethane composites. Summary of the Invention

[0005] This invention addresses the technical shortcomings of existing polyurethane pultrusion resins, such as high cost, high water sensitivity, short operating time, and insufficient mechanical properties, by providing a low-cost modified polyurethane resin for pultrusion and winding processes, and its preparation method. By optimizing the raw material ratio and preparation process of the two-component system, this invention significantly improves the mechanical properties, glass transition temperature, and surface hardness of the resin while reducing raw material costs by 10%-20%. Simultaneously, it achieves low water sensitivity and a long operating time at room temperature. Furthermore, the system is solvent-free and VOC-free, exhibiting excellent environmental friendliness, and is suitable for open-groove pultrusion and winding processes.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a low-cost modified polyurethane resin, comprising a two-component polyurethane resin system, wherein the two-component polyurethane resin system includes a white component and a black component; the white component is composed of the following raw materials by weight percentage: 1%–10% polyether polyol NJ-303, 30%–50%... The composition comprises: a bifunctional acrylate monomer, 10%–30% polyester polyol C1124, 20%–50% polyester polyol C1084, 0.01%–0.05% organotin catalyst, and 1%–5% release agent for polyurethane composite pultrusion processes; the black component is composed of the following raw materials by weight percentage: 50%–98% polymethylene polyphenyl isocyanate PM400, and 1%–5% initiator TBPB; the bifunctional acrylate monomer is one or a mixture of DEGDMA, TPGDA, DEGDA, DPGDA, and HDDMA; the white component and the black component are mixed and cured at a mass ratio of 1:0.40–0.55 during use.

[0007] Furthermore, the polyether polyol NJ-303 has a functionality of 3 and a viscosity of 450 mPa at 25°C. s, hydroxyl value is 475mgKOH / g.

[0008] Furthermore, polyester polyol C1124 is a five-molecule polyester diol synthesized from ethylene glycol, neopentyl glycol, and maleic anhydride, with a molecular weight of 390. It is liquid at room temperature and has a viscosity of 20,000-40,000 mPa at 25°C. The hydroxyl value is 350 mg KOH / g; the polyester polyol C1084 is a three-molecule polyester diol synthesized from ethylene glycol, neopentyl glycol, and maleic anhydride, with a molecular weight of 356. It is liquid at room temperature and has a viscosity of 20,000-40,000 mPa at 25°C. s, hydroxyl value is 300mgKOH / g.

[0009] Further, DEGDMA is diethylene glycol dimethacrylate, with a molecular weight of 242 and a viscosity of 3-10 cps at 25°C, CAS number 2358-84-1; TPGDA is tripropylene glycol diacrylate, with a molecular weight of 300 and a viscosity of 15-25 cps at 25°C, CAS number 42978-66-5; DEGDA is diethylene glycol diacrylate, with a molecular weight of 214 and a viscosity of 10-20 cps at 25°C, CAS number 4074-88-8; DPGDA is dipropylene glycol diacrylate, with a molecular weight of 242 and a viscosity of 7-13 cps at 25°C, CAS number 57472-68-1; HDDMA is 1,6-hexanediol dimethacrylate, with a molecular weight of 254 and a viscosity of 6-12 cps at 25°C, CAS number 6606-59-3.

[0010] Furthermore, the organotin catalyst is one or a mixture of two of dibutyltin dilaurate and stannous octoate.

[0011] Furthermore, polymethyl polyphenyl isocyanate PM400 is a product manufactured by Wanhua Chemical Group Co., Ltd.; the initiator TBPB is tert-butyl peroxide.

[0012] A method for preparing modified polyurethane resin includes the following steps: Step 1, Preparation of the white component: Polyester polyols C1124 and C1084 were preheated at 65°C. The preheated polyester polyols C1124 and C1084 were weighed by weight and added to the reactor, and stirred for 30 min. Then, polyether polyol NJ-303 and bifunctional acrylate monomers were added, and stirring was continued for 1 h. Finally, organotin catalyst and internal release agent were added, and stirring was carried out for 1 h until the mixture was homogeneous. The mixture was then filtered and packaged to obtain the white component. Step 2, Preparation of black component: Weigh polymethyl polyphenyl isocyanate PM400 and initiator TBPB by weight percentage and add them to the mixing tank. Stir for 2 hours until the mixture is uniform. After filtration and packaging, the black component is obtained. Step 3, Resin Curing and Molding: Mix the white component and the black component at a mass ratio of 1:0.40 to 0.55, stir evenly, and then use them for pultrusion and winding processes. Curing is carried out at room temperature or under heating conditions to obtain modified polyurethane resin products.

[0013] Furthermore, in step 1, the preheating time for polyester polyols C1124 and C1084 is 2-4 hours to ensure that the raw materials are free of agglomeration.

[0014] Furthermore, in steps 1 and 2, the stirring speed is 300-500 r / min, and the ambient temperature inside the reaction vessel and the stirring vessel is controlled at 25-30℃ and the humidity is controlled at 40%-60% during the stirring process.

[0015] Furthermore, in step 3, the heating and curing process is as follows: heat preservation at 90℃ for 1 hour + heat preservation at 120℃ for 2 hours + heat preservation at 130℃ for 1 hour.

[0016] The technical effects and advantages of this invention are as follows: 1. Significantly reduced costs and excellent economic benefits: This invention introduces a composite system of polyester polyols C1084 and C1124 to replace part of the polyether polyol, while reducing the amount of isocyanate PM400 by about 50%. Compared with the traditional polyether polyol-isocyanate system, the raw material cost of the modified formulation is reduced by 10%-20%, which greatly enhances the market competitiveness of polyurethane resin in the field of composite materials and is suitable for large-scale industrial production.

[0017] 2. Significantly improved mechanical properties and excellent performance: This invention significantly improves the crosslinking density of the resin after curing through the synergistic modification of polyether polyol, polyester polyol and difunctional acrylate monomer. The tensile strength of the pure resin is increased to 91.28 MPa, which is more than 18.6% higher than the traditional system; the flexural strength is increased to 158 MPa, which is more than 28.4% higher than the traditional system; the tensile modulus and flexural modulus are increased by 21.2% and 27.6% respectively; and the surface hardness (ShoreD) is greater than 95, which is more than 12% higher than the traditional system, fully meeting the mechanical performance requirements of high-end pultruded and wound composite materials.

[0018] 3. Significantly improved glass transition temperature and enhanced high-temperature resistance: The modified polyurethane resin of this invention achieves a Tg of over 125°C after curing, with a Tg of 133°C in the optimal embodiment. This is more than 15°C higher than the traditional polyether polyol-isocyanate system, with a maximum improvement of 25°C. This significantly improves the high-temperature resistance of polyurethane resin and expands its application range under high-temperature conditions.

[0019] 4. Low water sensitivity and strong process adaptability: The modified system of this invention breaks through the technical bottleneck of traditional polyurethane resins being sensitive to moisture. It can be operated without a low humidity environment and can be directly applied to pultrusion and winding processes in open glue tanks, which greatly reduces the environmental control costs in the production process and simplifies the operation process.

[0020] 5. Long operating time at room temperature and high process error tolerance: After the modified polyurethane resin white and black components of this invention are mixed, the gel time of 150g system at 25℃ reaches 65min, and the operating time at room temperature is >1h, which is much longer than the 15-25min of the traditional system. This effectively improves the operation error tolerance of pultrusion and winding processes, reduces product molding defects caused by untimely operation, and improves the yield.

[0021] 6. Excellent environmental performance and compliance with policy requirements: The two-component system of this invention does not contain any organic solvents, has no VOC emissions, and releases no toxic or harmful substances during production and use. It complies with current national environmental protection policies and the development trend of green manufacturing, and is an environmentally friendly material.

[0022] 7. Good compatibility with fibers and excellent composite material performance: The modified polyurethane resin of this invention has excellent compatibility with reinforcing fibers such as glass fiber and carbon fiber. The pultruded composite material samples are superior to epoxy resin-based composite materials in terms of 90° tensile strength, bulk layer shear, and injection layer shear. The density is close to that of the epoxy resin system, and the fiber mass content can reach more than 85%. It can completely replace epoxy resin in high-end composite material products such as wind power pultruded beams and plates.

[0023] 8. Highly adjustable formulation and process, adaptable to different needs: This invention can achieve gradient control of resin performance by adjusting the raw material ratio of white component and the mixing ratio of white and black components (1:0.40~0.55), meeting the differentiated needs of different fields and processes for resin mechanical properties, curing speed and operating time, and has a wide range of applications. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

[0025] The present invention will be further described in detail below with reference to specific embodiments. These embodiments are only used to explain the present invention and are not intended to limit the scope of protection of the present invention. Experimental methods in the present invention that do not specify specific conditions are all conventional methods; raw materials that do not specify specific specifications are all commercially available conventional raw materials.

[0026] Raw material description 1. Polyether polyol NJ-303: Functionality 3, viscosity at 25℃ 450mPa s, hydroxyl value 475mgKOH / g, commercially available; 2. Bifunctional acrylate monomers: DEGDMA (Cas2358-84-1), TPGDA (Cas42978-66-5), DEGDA (Cas4074-88-8), DPGDA (Cas57472-68-1), HDDMA (Cas6606-59-3), all of which are commercially available; 3. Polyester polyol C1124: A five-molecule polyester diol synthesized from ethylene glycol / neopentyl glycol / maleic anhydride, with a molecular weight of 390 and a viscosity of 20,000-40,000 mPa at 25°C. s, hydroxyl value 350mgKOH / g, commercially available; 4. Polyester polyol C1084: A three-molecule polyester diol synthesized from ethylene glycol / neopentyl glycol / maleic anhydride, with a molecular weight of 356 and a viscosity of 20,000-40,000 mPa at 25°C. s, hydroxyl value 300mgKOH / g, commercially available; 5. Organotin catalysts: dibutyltin dilaurate, stannous octoate, commercially available; 6. Internal release agent: A commercially available internal release agent specifically for the pultrusion process of polyurethane composite materials; 7. Polymethyl polyphenyl isocyanate PM400: Wanhua Chemical, commercially available; 8. Initiator TBPB: tert-butyl peroxide, commercially available.

[0027] Example 1 A low-cost modified polyurethane resin for pultrusion and winding processes, with the following weight ratio of white and black components: White component (total weight 1039 parts) Polyester polyol C1124: 160 parts (15.4%), polyester polyol C1084: 370 parts (35.6%), polyether polyol NJ-303: 70 parts (6.7%), bifunctional acrylate monomer (DEGDMA+TPGDA=1:1): 400 parts (38.5%), dibutyltin dilaurate: 4 parts (0.4%), internal mold release agent: 35 parts (3.4%). Black material components (total weight 1000 parts) PM400: 970 (97%), TBPB: 30 (3%) The mixing mass ratio of white component to black component is 100:50.

[0028] Its preparation method includes the following steps: Step 1: Preparation of white component: 160 parts of C1124 and 370 parts of C1084 were preheated in a 65℃ oven for 3 hours, then removed and added to a reaction vessel, stirred at 300 rpm for 30 minutes; 70 parts of NJ-303 and 400 parts of DEGDMA+TPGDA mixed monomers were added, and stirred at 400 rpm for 1 hour; 4 parts of dibutyltin dilaurate and 35 parts of internal release agent were added, and stirred at 400 rpm for 1 hour. After mixing evenly, the mixture was filtered and packaged to obtain the white component; during the stirring process, the temperature of the reaction vessel was controlled at 25℃ and the humidity at 50%. Step 2, Preparation of Black Material Components: 970 parts PM400 and 30 parts TBPB were added to a stirred tank and stirred at 350 rpm for 2 hours. After thorough mixing, the mixture was filtered and dispensed to obtain the black material components. During the stirring process, the temperature of the stirred tank was controlled at 28℃ and the humidity at 45%. Step 3, Mixing and Curing: Mix the white component and the black component at a mass ratio of 100:50, stir at 400r / min for 5min until uniform, and use for pultrusion and winding processes.

[0029] The modified polyurethane resin of this embodiment was subjected to performance tests, including white component viscosity, black component viscosity, mixed viscosity, room temperature gel time, and water sensitivity. The test methods and results are shown in Table 1.

[0030]

[0031] Table 1 As shown in Table 1, the modified polyurethane resin of this embodiment has a suitable mixing viscosity, a significantly extended gel time at room temperature, and is not sensitive to moisture. It can be operated in a normal temperature and humidity environment and is fully compatible with pultrusion and winding processes in open glue tanks.

[0032] Example 2 A low-cost modified polyurethane resin for pultrusion and winding processes has the same white component and black component ratio and preparation method as in Example 1, with a white component to black component mixing mass ratio of 100:50.

[0033] The mixed resin was made into a resin casting and cured according to the process of 90℃ 1h + 120℃ 2h + 130℃ 1h. The tensile properties, flexural properties, glass transition temperature and surface hardness of the casting were tested according to national standards. The test methods and results are shown in Table 2.

[0034]

[0035] Table 2 As shown in Table 2, after curing, the modified polyurethane resin in this embodiment exhibits significantly improved tensile and flexural mechanical properties, a marked increase in Tg, and a significant enhancement in surface hardness. Only the elongation at break decreases slightly, fully meeting the performance requirements of high-end pultruded and wound composite materials.

[0036] Example 3 A low-cost modified polyurethane resin for pultrusion and winding processes has the same white component and black component ratio and preparation method as in Example 1, with a white component to black component mixing mass ratio of 100:50.

[0037] The mixed resin was combined with 468GE-2000 glass fiber and pultruded to produce a wind power pultruded beam plate composite material sample. The density, fiber mass content, tensile properties, and interlaminar shear properties of the sample were tested according to national standards and compared with the 468GE-2000+epoxy resin system. The test methods and results are shown in Table 3.

[0038]

[0039] Table 3 As shown in Table 3, the modified polyurethane resin of this invention has excellent compatibility with glass fiber. The density and fiber mass content of the composite material are close to those of the epoxy resin system. The 90° tensile strength, bulk shear, and injection shear properties are all superior to those of the epoxy resin system. The 0° tensile strength is slightly improved, and only the 0° tensile modulus and Tg are slightly lower than those of the epoxy resin system. It can completely replace epoxy resin in high-end composite material products such as wind power pultruded beams and plates.

[0040] Example 4 A low-cost modified polyurethane resin for pultrusion and winding processes, with the following weight ratio of white and black components: White component (total weight 1049 parts) Polyester polyol C1124: 160 parts (15.2%), polyester polyol C1084: 460 parts (43.8%), polyether polyol NJ-303: 30 parts (2.9%), bifunctional acrylate monomer (DPGDA+HDDMA=1:1): 350 parts (33.4%), stannous octoate: 4 parts (0.4%), internal mold release agent: 35 parts (3.3%). Black material components (total weight 1000 parts) PM400: 975 (97.5%), TBPB: 25 (2.5%); The mixing mass ratio of white component to black component is 100:40.

[0041] The preparation method is the same as in Example 1. The mixed resin is made into a casting and cured at 90℃ for 1h + 120℃ for 2h + 130℃ for 1h. The performance is then tested and compared with the test results of Example 2 (100:50). The results are shown in Table 4.

[0042]

[0043] Table 4 As shown in Table 4, reducing the amount of black material (white to black material ratio 100:40) slightly reduces the performance of all properties of the modified polyurethane resin, but it is still far superior to the traditional polyether system polyurethane resin. This indicates that the present invention can achieve gradient control of resin performance by adjusting the mixing ratio of white and black materials, so as to meet the differentiated needs of different fields.

[0044] Example 5 A low-cost modified polyurethane resin for pultrusion and winding processes, with the following weight ratio of white and black components: White component (total weight 1025.05 parts) Polyester polyol C1124: 100 parts (9.75%), polyester polyol C1084: 200 parts (19.51%), polyether polyol NJ-303: 10 parts (0.97%), bifunctional acrylate monomer (DEGDA): 500 parts (48.78%), dibutyltin dilaurate + stannous octoate (1:1): 0.05 parts (0.005%), internal mold release agent: 15 parts (1.46%). Black material components (total weight 1000 parts) PM400: 500 parts (50%), TBPB: 50 parts (5%); the mixing mass ratio of white component to black component is 100:55.

[0045] The preparation method is the same as in Example 1. After testing, the modified polyurethane resin of this example has a 20% lower cost than the traditional system, a gel time of 60 min at room temperature, is not sensitive to moisture, has a tensile strength of 88.5 MPa, a flexural strength of 152 MPa, a Tg of 128℃, and a surface hardness of Shore D95. All properties are superior to those of the traditional polyether system polyurethane resin.

[0046] Example 6 A low-cost modified polyurethane resin for pultrusion and winding processes, with the following weight ratio of white and black components: White component (total weight 1010 parts) Polyester polyol C1124: 300 parts (29.7%), polyester polyol C1084: 500 parts (49.5%), polyether polyol NJ-303: 100 parts (9.9%), bifunctional acrylate monomer (HDDMA): 300 parts (29.7%), dibutyltin dilaurate: 0.1 parts (0.01%), internal mold release agent: 50 parts (4.95%). Black material components (total weight 1000 parts) PM400: 980 samples (98%), TBPB: 10 samples (1%). The mixing mass ratio of white component to black component is 100:45.

[0047] The preparation method is the same as in Example 1. After testing, the modified polyurethane resin of this example has a 10% lower cost than the traditional system, a gel time of 62 min at room temperature, is not sensitive to moisture, has a tensile strength of 89.3 MPa, a flexural strength of 155 MPa, a Tg of 130℃, and a surface hardness of Shore D96. All properties are superior to those of the traditional polyether system polyurethane resin.

[0048] The specific embodiments described above are merely illustrative and are not intended to limit the scope of protection of this invention. Those skilled in the art can fine-tune the raw material ratios and preparation process parameters within the scope of the technical solutions of this invention. All technical solutions obtained through equivalent substitution or equivalent transformation fall within the scope of protection of this invention.

[0049] The modified polyurethane resin of this invention can be widely used in pultrusion and filament winding of composite materials in fields such as wind power, rail transportation, building materials, and petrochemicals, such as wind power pultruded beams, fiberglass pipes, pultruded profiles, and filament winding storage tanks, and has broad market application prospects.

Claims

1. A low-cost modified polyurethane resin, characterized in that, The product is composed of a two-component polyurethane resin system, comprising a white component and a black component. The white component, by weight percentage, consists of the following raw materials: 1%–10% polyether polyol NJ-303, 30%–50% difunctional acrylate monomer, 10%–30% polyester polyol C1124, 20%–50% polyester polyol C1084, 0.01%–0.05% organotin catalyst, and 1%–5% internal release agent for polyurethane composite pultrusion processes. The black component, by weight percentage, consists of the following raw materials: 50%–98% polymethylene polyphenyl isocyanate PM400, and 1%–5% initiator TBPB. The difunctional acrylate monomer is one or more of DEGDMA, TPGDA, DEGDA, DPGDA, and HDDMA. The white and black components are mixed and cured at a mass ratio of 1:0.40–0.

55.

2. The low-cost modified polyurethane resin according to claim 1, characterized in that, The polyether polyol NJ-303 has a functionality of 3 and a viscosity of 450 mPa at 25°C. s, hydroxyl value is 475mgKOH / g.

3. The low-cost modified polyurethane resin according to claim 1, characterized in that, The polyester polyol C1124 is a five-molecule polyester diol synthesized from ethylene glycol, neopentyl glycol, and maleic anhydride, with a molecular weight of 390. It is liquid at room temperature and has a viscosity of 20,000-40,000 mPa at 25°C. The hydroxyl value is 350 mg KOH / g; the polyester polyol C1084 is a three-molecule polyester diol synthesized from ethylene glycol, neopentyl glycol, and maleic anhydride, with a molecular weight of 356. It is liquid at room temperature and has a viscosity of 20,000-40,000 mPa at 25°C. s, hydroxyl value is 300mgKOH / g.

4. The low-cost modified polyurethane resin according to claim 1, characterized in that, The DEGDMA is diethylene glycol dimethacrylate, with a molecular weight of 242 and a viscosity of 3-10 cps at 25°C, CAS number 2358-84-1; the TPGDA is tripropylene glycol diacrylate, with a molecular weight of 300 and a viscosity of 15-25 cps at 25°C, CAS number 42978-66-5; the DEGDA is diethylene glycol diacrylate, with a molecular weight of 214 and a viscosity of 10-20 cps at 25°C, CAS number 4074-88-8; the DPGDA is dipropylene glycol diacrylate, with a molecular weight of 242 and a viscosity of 7-13 cps at 25°C, CAS number 57472-68-1; the HDDMA is 1,6-hexanediol dimethacrylate, with a molecular weight of 254 and a viscosity of 6-12 cps at 25°C, CAS number 6606-59-3.

5. The low-cost modified polyurethane resin according to claim 1, characterized in that, The organotin catalyst is one or a mixture of two of dibutyltin dilaurate and stannous octoate.

6. The low-cost modified polyurethane resin according to claim 1, characterized in that, The polymethyl polyphenyl isocyanate PM400 is a product manufactured by Wanhua Chemical Group Co., Ltd.; the initiator TBPB is tert-butyl peroxide.

7. A method for preparing the modified polyurethane resin according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1, Preparation of the white component: Polyester polyols C1124 and C1084 were preheated at 65°C. The preheated polyester polyols C1124 and C1084 were weighed by weight and added to the reactor, and stirred for 30 min. Then, polyether polyol NJ-303 and bifunctional acrylate monomers were added, and stirring was continued for 1 h. Finally, organotin catalyst and internal release agent were added, and stirring was carried out for 1 h until the mixture was homogeneous. The mixture was then filtered and packaged to obtain the white component. Step 2, Preparation of black component: Weigh polymethyl polyphenyl isocyanate PM400 and initiator TBPB by weight percentage and add them to the mixing tank. Stir for 2 hours until the mixture is uniform. After filtration and packaging, the black component is obtained. Step 3, Resin Curing and Molding: Mix the white component and the black component at a mass ratio of 1:0.40 to 0.55, stir evenly, and then use them for pultrusion and winding processes. Curing is carried out at room temperature or under heating conditions to obtain modified polyurethane resin products.

8. The method for preparing the modified polyurethane resin according to claim 7, characterized in that, In step 1, the preheating time for polyester polyols C1124 and C1084 is 2-4 hours to ensure that the raw materials are free of caking.

9. The method for preparing the modified polyurethane resin according to claim 7, characterized in that, In steps 1 and 2, the stirring speed is 300-500 r / min, and the ambient temperature inside the reaction vessel and the stirring vessel is controlled at 25-30℃ and the humidity is controlled at 40%-60% during the stirring process.

10. The method for preparing the modified polyurethane resin according to claim 7, characterized in that, In step 3, the heating and curing process is as follows: heat preservation at 90℃ for 1 hour + heat preservation at 120℃ for 2 hours + heat preservation at 130℃ for 1 hour.

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