A fan blade protection polyurethane film and a method of making the same
By employing a multi-step melt blending process of reactive silicone composite and polycaprolactone-type TPU in the protective film of wind turbine blades, a composite material with excellent comprehensive performance was prepared, which solved the problems of insufficient weather resistance and toughness of existing protective film materials and improved the reliability and operational stability of wind turbines.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG HUANLONG NEW MATERIAL SCI & TECH
- Filing Date
- 2026-03-20
- Publication Date
- 2026-06-05
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of wind turbine generators, specifically a protective polyurethane film for wind turbine blades and its preparation method. Background Technology
[0002] Wind energy, as a clean and safe renewable energy source, has become one of the most commercially viable projects in the new energy field. Wind turbine blades are the power source of wind turbines and a key component of wind turbine generator sets. Their structure and strength are crucial to the reliability of the wind turbine, and their performance directly affects the stability and power generation efficiency of the entire unit. Existing protective films often use materials such as PVC and PE, which have problems such as poor weather resistance, weak adhesion, residue after removal, or insufficient toughness leading to breakage. Developing TPU protective films for wind turbine blades is essential for the safe and efficient operation of wind turbines. Summary of the Invention
[0003] To address the aforementioned technical problems in existing technologies, this invention employs a reactive / compatible silicone composite as a modifier and optimizes a multi-step melt blending process to achieve uniform dispersion and interfacial bonding at the microscale with pre-synthesized polycaprolactone-type TPU particles, thereby preparing a composite material with excellent comprehensive performance suitable for wind turbine blade protective films. The specific technical solution is as follows:
[0004] A method for preparing a protective polyurethane film for wind turbine blades includes the following steps:
[0005] Step 1: Preparation of PCL-TPU
[0006] 1. Raw material pretreatment: Place PCL polyol in a reaction vessel and dehydrate it; mix BDO and BEPD and dehydrate to obtain BDO / BEPD mixed chain extender; dry HDI before use, or use freshly opened dried product directly;
[0007] 2. Synthesis of prepolymer: The dehydrated PCL polyol was cooled and HDI was added dropwise under dry nitrogen protection. After the addition was complete, a catalyst was added and the temperature was maintained at 70-100℃ while stirring until the prepolymerization reaction was completed, resulting in a transparent HDI-PCL prepolymer.
[0008] 3. Chain extension reaction: Preheat the dehydrated BDO / BEPD mixed chain extender, and add it to the HDI-PCL prepolymer in one go under high speed stirring. After vigorous stirring, quickly put the viscous reaction material into the mold.
[0009] 4. Curing and post-processing: Immediately transfer the mold containing the material into a forced-air drying oven to allow the remaining -NCO groups to react completely; after curing, remove the cured PCL-TPU sheet and cool it to room temperature; crush the PCL-TPU sheet into granules, melt extrude, underwater pelletize, and dry.
[0010] Step 2: Preparation of PMDS-TPU
[0011] 1. Raw material pretreatment: Polycaprolactone diol is placed in a reaction vessel and dehydrated;
[0012] 2. Synthesis of prepolymer: Dehydrated polycaprolactone diol is reacted with excess diisocyanate to generate PCL prepolymer with -NCO ends;
[0013] 3. Introduction of PDMS-terminal amino chain extension and end-capping: Dissolve PDMS-terminal amino groups in a solvent and slowly add them dropwise to the above prepolymer solution under ice-water bath cooling and strong stirring; after the addition is complete, raise the temperature to 50-60℃ and continue the reaction for 1.5-3 hours.
[0014] 4. Post-treatment: Add a small amount of terminator slowly dropwise at room temperature or slightly above room temperature until the -NCO peak disappears. Pour the melt into a polytetrafluoroethylene mold and cure at 100-120℃ for 1-2 hours. After curing, remove the cured PMDS-TPU sheet and cool it to room temperature. Crush the PMDS-TPU sheet into granules, melt extrude, underwater pelletize, and dry.
[0015] Step 3: Preparation and Application of TPU and Silicone Composite Films
[0016] The PCL-TPU, PDMS-TPU, and other additives are mixed in a ratio of 99-59:1-40:1 to form a film with a thickness of 0.3-2.0 mm.
[0017] Furthermore, in step one, the ratio of BDO to BEPD is 80-60:20-40.
[0018] Furthermore, in step one, the dehydrated PCL polyol is cooled to 70-100℃.
[0019] Furthermore, in step two, the polycaprolactone diol reacts with an excess of diisocyanate at 60-80°C.
[0020] Furthermore, step 2.3 also includes further regulation and end-capping: adding the small molecule chain extender BDO, reacting at 50~60℃ for 1-2 hours, and finally end-capping with a small molecule alcohol or monoaminosiloxane.
[0021] A protective polyurethane film for wind turbine blades is prepared using the aforementioned preparation method.
[0022] The polyurethane protective film for wind turbine blades of the present invention can be used directly or in combination with other support layers for the protection of wind turbine blades. The silicone layer enriched on its surface provides stable peel strength, excellent hydrophobicity and UV resistance; the TPU matrix provides high elasticity, tear resistance and low-temperature impact resistance; the introduction of urethane bonds brings hydrogen bonding, which can significantly improve the strength, toughness, wear resistance and adhesion to other materials of the material. The final performance is a combination and balance of the biocompatibility / softness of silicone and the mechanical properties of polyurethane. Detailed Implementation
[0023] The present invention will be further described below with reference to the embodiments.
[0024] Example 1
[0025] The method for preparing the protective polyurethane film for wind turbine blades in this embodiment includes the following steps:
[0026] I. Preparation of Polycaprolactone TPU
[0027] 1. Raw material pretreatment: Polycaprolactone diol (PCL 1000) is placed in a reaction vessel and dehydrated for 2 hours under a vacuum of -0.095 MPa or higher and a temperature of 110±5℃ until the moisture content is below 0.03%; 1,4-Butanediol (BDO) and ethylbutylpropylene glycol (BEPD) are mixed in a ratio of 70:30 and dehydrated for 0.5 hours under a vacuum of -0.095 MPa at 80℃; 1,6-hexamethylene diisocyanate (HDI) needs to be dried with a 4Å molecular sieve before use, or freshly opened dried product can be used directly;
[0028] 2. Synthesis of the prepolymer: The dehydrated polycaprolactone diol was cooled to 80±2℃, and HDI was slowly added dropwise using a constant pressure dropping funnel under dry nitrogen protection. After the addition was complete, stannous octoate catalyst was added, and the temperature was maintained at 80±2℃. The reaction was stirred continuously for 2 hours. During this period, the -NCO content of the system was monitored by di-n-butylamine titration. When the measured value was close to the theoretical -NCO content of the prepolymer, the prepolymerization reaction was considered to be complete, and a transparent HDI-PCL prepolymer was obtained.
[0029] 3. Chain extension reaction: Adjust the temperature of the HDI-PCL prepolymer to 75±2℃; preheat the dehydrated BDO / BEPD mixed chain extender to 70℃, and add it to the HDI-PCL prepolymer in one go under high-speed stirring (e.g., 1000 rpm); this step must be completed within 30 seconds and the mixture must be homogeneous. After vigorous stirring for 1-2 minutes, observe a sharp increase in the viscosity of the material (milky white, pasty), and quickly pour the viscous reaction material into a preheated PTFE template or steel tray coated with a release agent;
[0030] 4. Curing and Post-treatment: Immediately transfer the mold containing the material into a forced-air drying oven and cure at 100℃ for 4 hours, followed by a further curing at 110℃ for 2 hours; this process ensures the complete reaction of any remaining -NCO groups. After curing, remove the cured PCL-TPU sheet and cool it to room temperature; crush the PCL-TPU sheet into granules, and use a twin-screw extruder to perform melt extrusion, underwater pelletizing, and drying within a processing temperature range of 160-180℃ to homogenize the material, remove residual monomers and oligomers, and granulate it for subsequent injection molding or extrusion molding.
[0031] II. Preparation of polydimethylsiloxane (PMDS)-polyurethane (TPU) with side-chain amino groups
[0032] Polydimethylsiloxane (PDMS-diamine) with amino groups (-NH2) at both ends is introduced as an "active macromolecular chain extender" by taking advantage of the higher reactivity of amino groups with -NCO.
[0033] 1. Raw material pretreatment: Place polycaprolactone diol in a reaction vessel and dehydrate it until the moisture content is below 0.03%. Dry it with 4Å molecular sieves, or use freshly opened dried product directly.
[0034] 2. Synthesis of prepolymer: Dehydrated polycaprolactone diol is reacted with excess 1,6-hexanediisocyanate (e.g., NCO:OH = 2:1) at 75°C to generate a PCL prepolymer with -NCO ends;
[0035] 3. Introduction of PDMS-terminated amino groups for chain extension and end-capping: Dissolve PDMS-terminated amino groups in a solvent and slowly add them dropwise to the PCL prepolymer solution over 1 hour under ice-water bath cooling and vigorous stirring. Since -NH2 and -NCO react extremely rapidly, the dropping rate and temperature (< 40℃) must be strictly controlled to prevent localized gelation. After the addition is complete, raise the temperature to 55℃ and continue the reaction for 2 hours. At this point, PDMS acts as a chain extender, linking the PCL prepolymer to form (PCL-urethane-PDMS-urethane-PCL)n-type triblock or multiblock copolymers. Further regulation and end-capping: If it is necessary to adjust the hard segment content or introduce more crosslinks, a measured amount of small molecule chain extender (BDO) can be added at this stage, and the reaction can be carried out at 60℃ for 1 hour. Finally, small molecule alcohols (such as butanol) or monoaminosiloxanes can be used for end-capping to control the molecular weight or introduce functional end groups.
[0036] 4. Post-processing: Add a small amount of terminator (such as methanol) to consume the remaining -NCO. Pour the melt into a PTFE mold and cure at 120℃ for 1.2 hours. After curing, remove the cured PMDS-TPU sheet and cool to room temperature. Crush the PMDS-TPU sheet into granules, melt-extrude using a twin-screw extruder, granulate underwater, and dry.
[0037] III. Preparation and Application of TPU and Silicone Composite Films
[0038] The modified PCL-TPU, PDMS-TPU, and other additives were mixed in a ratio of 79:20:1 and then processed into a 2.0 mm thick film using a casting extrusion or blown film process. The film can be subjected to online corona treatment before winding.
[0039] Example 2
[0040] I. Preparation of Polycaprolactone TPU
[0041] 1. Raw material pretreatment: Polycaprolactone diol (PCL 1000) is placed in a reaction vessel and dehydrated for 2 hours under a vacuum of -0.095 MPa or higher and a temperature of 110±5℃ until the moisture content is below 0.03%; 1,4-Butanediol (BDO) and ethylbutylpropylene glycol (BEPD) are mixed in a ratio of 65:35 and dehydrated for 0.5 hours under a vacuum of -0.095 MPa at 80℃; 1,6-hexamethylene diisocyanate (HDI) needs to be dried with a 4Å molecular sieve before use, or freshly opened dried product can be used directly;
[0042] 2. Synthesis of the prepolymer: The dehydrated polycaprolactone diol was cooled to 90±2℃, and HDI was slowly added dropwise using a constant pressure dropping funnel under dry nitrogen protection. After the addition was complete, stannous octoate catalyst was added, and the temperature was maintained at 90±2℃. The reaction was stirred continuously for 2 hours. During this period, the -NCO content of the system was monitored by di-n-butylamine titration. When the measured value was close to the theoretical -NCO content of the prepolymer, the prepolymerization reaction was considered to be complete, and a transparent HDI-PCL prepolymer was obtained.
[0043] 3. Chain extension reaction: Adjust the temperature of the HDI-PCL prepolymer to 75±2℃; preheat the dehydrated BDO / BEPD mixed chain extender to 70℃, and add it to the HDI-PCL prepolymer in one go under high-speed stirring (e.g., 1000 rpm); this step must be completed within 30 seconds and the mixture must be homogeneous. After vigorous stirring for 1-2 minutes, observe a sharp increase in the viscosity of the material (milky white, pasty), and quickly pour the viscous reaction material into a preheated PTFE template or steel tray coated with a release agent;
[0044] 4. Curing and Post-treatment: Immediately transfer the mold containing the material into a forced-air drying oven and cure at 100℃ for 4 hours, followed by a further curing at 110℃ for 2 hours; this process ensures the complete reaction of any remaining -NCO groups. After curing, remove the cured PCL-TPU sheet and cool it to room temperature; crush the PCL-TPU sheet into granules, and use a twin-screw extruder to perform melt extrusion, underwater pelletizing, and drying within a processing temperature range of 160-180℃ to homogenize the material, remove residual monomers and oligomers, and granulate it for subsequent injection molding or extrusion molding.
[0045] II. Preparation of polydimethylsiloxane (PMDS)-polyurethane (TPU) with side-chain amino groups
[0046] Polydimethylsiloxane (PDMS-diamine) with amino groups (-NH2) at both ends is introduced as an "active macromolecular chain extender" by taking advantage of the higher reactivity of amino groups with -NCO.
[0047] 1. Raw material pretreatment: Place polycaprolactone diol in a reaction vessel and dehydrate it until the moisture content is below 0.03%. Dry it with 4Å molecular sieves, or use freshly opened dried product directly.
[0048] 2. Synthesis of prepolymer: Dehydrated polycaprolactone diol is reacted with excess 1,6-hexamethylene diisocyanate (e.g., NCO:OH = 2:1) at 65°C to generate a PCL prepolymer with -NCO ends;
[0049] 3. Introduction of PDMS-terminated amino groups for chain extension and end-capping: Dissolve PDMS-terminated amino groups in a solvent and slowly add them dropwise to the PCL prepolymer solution over 0.5 hours under ice-water bath cooling and vigorous stirring. Since the reaction between -NH2 and -NCO is extremely rapid, the dropping rate and temperature (< 40℃) must be strictly controlled to prevent localized gelation. After the addition is complete, the temperature is raised to 60℃ and the reaction continues for 1.5 hours. At this point, PDMS acts as a chain extender, linking the PCL prepolymer to form (PCL-urethane-PDMS-urethane-PCL)n-type triblock or multiblock copolymers. Further regulation and end-capping: If it is necessary to adjust the hard segment content or introduce more crosslinks, a measured amount of small molecule chain extender (BDO) can be added at this stage, and the reaction can be carried out at 50℃ for 2 hours. Finally, small molecule alcohols (such as butanol) or monoaminosiloxanes can be used for end-capping to control the molecular weight or introduce functional end groups.
[0050] 4. Post-processing: Add a small amount of terminator (such as methanol) to consume the remaining -NCO. Pour the melt into a PTFE mold and cure at 105℃ for 2 hours. After curing, remove the cured PMDS-TPU sheet and cool to room temperature. Crush the PMDS-TPU sheet into granules, melt-extrude using a twin-screw extruder, granulate underwater, and dry.
[0051] III. Preparation and Application of TPU and Silicone Composite Films
[0052] The modified PCL-TPU, PDMS-TPU, and other additives are mixed in a ratio of 69:30:1. The other additives can be slip agents. The mixture is then processed into a 2.0 mm thick film using either cast extrusion or blown film technology. The film can be subjected to online corona treatment before winding.
[0053] The performance tests of the diaphragm and the granules used in the diaphragm are shown in Tables 1 and 2:
[0054]
[0055] Table 1. Formulation of polyurethane film for wind turbine blade protection.
[0056]
[0057] Table 2. Properties of the membrane and the granules used for the membrane.
[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical implementation of the present invention without departing from the scope of the present invention are within the scope of the present invention.
Claims
1. A method for preparing a protective polyurethane film for wind turbine blades, characterized by comprising the following steps: Step 1: Preparation of PCL-TPU 1. Raw material pretreatment: Place PCL polyol in a reaction vessel and dehydrate it; mix BDO and BEPD and dehydrate to obtain BDO / BEPD mixed chain extender; dry HDI before use, or use freshly opened dried product directly; 2. Synthesis of prepolymer: The dehydrated PCL polyol was cooled and HDI was added dropwise under dry nitrogen protection. After the addition was complete, a catalyst was added and the temperature was maintained at 70-100℃ while stirring until the prepolymerization reaction was completed, resulting in a transparent HDI-PCL prepolymer.
3. Chain extension reaction: Preheat the dehydrated BDO / BEPD mixed chain extender, and add it to the HDI-PCL prepolymer in one go under high speed stirring. After vigorous stirring, quickly put the viscous reaction material into the mold.
4. Curing and post-processing: Immediately transfer the mold containing the material into a forced-air drying oven to allow the remaining -NCO groups to react completely; after curing, remove the cured PCL-TPU sheet and cool it to room temperature; crush the PCL-TPU sheet into granules, melt extrude, underwater pelletize, and dry. Step 2: Preparation of PMDS-TPU 1. Raw material pretreatment: Polycaprolactone diol is placed in a reaction vessel and dehydrated; 2. Synthesis of prepolymer: Dehydrated polycaprolactone diol is reacted with excess diisocyanate to generate PCL prepolymer with -NCO ends; 3. Introduction of PDMS-terminal amino chain extension and end-capping: Dissolve PDMS-terminal amino groups in a solvent and slowly add them dropwise to the above prepolymer solution under ice-water bath cooling and strong stirring; after the addition is complete, raise the temperature to 50-60℃ and continue the reaction for 1.5-3 hours.
4. Post-treatment: Add a small amount of terminator slowly dropwise at room temperature or slightly above room temperature until the -NCO peak disappears. Pour the melt into a polytetrafluoroethylene mold and cure at 100-120℃ for 1-2 hours. After curing, remove the cured PMDS-TPU sheet and cool it to room temperature. Crush the PMDS-TPU sheet into granules, melt extrude, underwater pelletize, and dry. Step 3: Preparation and Application of TPU and Silicone Composite Films The PCL-TPU, PDMS-TPU, and other additives are mixed in a ratio of 99-59:1-40:1 to form a film with a thickness of 0.3-2.0 mm.
2. The method for preparing the protective polyurethane film for wind turbine blades as described in claim 1, characterized in that: In step one, the ratio of BDO to BEPD is 80-60:20-40.
3. The method for preparing the protective polyurethane film for wind turbine blades as described in claim 1, characterized in that: In step one, the dehydrated PCL polyol is cooled to 70-100℃.
4. The method for preparing the protective polyurethane film for wind turbine blades as described in claim 1, characterized in that: In step two, the polycaprolactone diol reacts with an excess of diisocyanate at 60-80°C.
5. The method for preparing the protective polyurethane film for wind turbine blades as described in claim 1, characterized in that: Step 2.3 also includes further regulation and end-capping: add the small molecule chain extender BDO, react at 50~60℃ for 1-2 hours, and finally end-cap with a small molecule alcohol or monoaminosiloxane.
6. A polyurethane film for protecting wind turbine blades, characterized in that: Prepared using the preparation method described in any one of claims 1-5.