A single-sided adhesive release fabric for wind turbine blade molding and its preparation method

Abstract

This invention relates to a single-sided adhesive release fabric for wind turbine blade molding and its preparation method. The method involves weaving filaments into a plain weave fabric, which is then cleaned and heat-set to obtain the release fabric substrate. A modified acrylic pressure-sensitive adhesive is applied to one side of the substrate in 2-5 stages, followed by separate drying. A coating balance coefficient is calculated based on the cumulative dry adhesive amount, 180° peel force, and air permeability. The termination point for coating is determined by comparing the results of two consecutive coating stages. Subsequently, a release paper protective layer is laminated to the outside of the adhesive layer to obtain the single-sided adhesive release fabric. The resulting release fabric exhibits moderate mold-mounting force, good air permeability retention, and clean peel performance, making it suitable for placement, positioning, and demolding during the wind turbine blade molding process.

Description

Technical Field

[0001] This invention relates to the technical field of release fabrics, and in particular to a single-sided adhesive release fabric for wind turbine blade molding and its preparation method. Background Technology

[0002] Wind turbine blades are typically manufactured using composite material molding processes. During the molding of components such as the blade shell and web, release materials need to be placed on the mold surface or in the layup system to facilitate the separation of the part from the mold or process materials after resin curing. Release cloth, as a commonly used release material, can isolate the resin system from the external process layers during molding and peel off with the process layers after curing, thereby obtaining a relatively stable surface condition of the part.

[0003] As wind turbine blades continue to increase in size, changes in mold surface curvature, coverage area, working position, and laying direction all place higher demands on the construction stability of the release fabric. In actual laying processes, the release fabric typically needs to cover large areas of curved surfaces, inclined surfaces, or localized vertical areas. Because the release fabric itself is a flexible fabric material, it is easily affected by factors such as gravity, airflow disturbances, manual pulling, and stress release during laying, adjustment, vacuuming, and subsequent resin infusion, resulting in positional shifts, localized lifting, or wrinkles. These phenomena affect the flatness of the molded surface and increase the workload of subsequent finishing and surface treatment.

[0004] To improve the laying state of the release fabric, temporary pressing, repeated manual adjustments, or local auxiliary fixing can be used in actual production. However, these methods are highly dependent on operator skill and on-site working conditions, and it is difficult to maintain a consistent laying effect in large-area blade molds. Especially in curved transition areas and vertical areas, maintaining a stable position of the release fabric throughout the molding process remains challenging.

[0005] Therefore, there is still a need in the field to improve the positional stability of the release fabric during the wind turbine blade forming and laying process, so that it can maintain a flat and stable attachment state after being laid in large curved surfaces, inclined surfaces and vertical areas. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned problems existing in the prior art and to provide a single-sided adhesive release fabric for wind turbine blade molding and its preparation method.

[0007] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a single-sided adhesive release fabric for wind turbine blade molding, comprising the following steps: S1: Nylon 66 filament, nylon 6 filament or polyester filament are woven into a plain weave fabric, and the plain weave fabric is cleaned and heat-set to obtain a release fabric substrate. S2: Measure the initial air permeability P0 of the release fabric substrate before coating; S3: Apply the modified acrylic pressure-sensitive adhesive to one side of the release cloth substrate and perform the first drying to complete the first coating; S4: Repeat the application and drying of modified acrylic pressure-sensitive adhesive on the same coating side of the release cloth substrate, so that the modified acrylic pressure-sensitive adhesive forms an adhesive layer layer by layer on one side of the release cloth substrate, and the total number of coatings is 2 to 5. S5: After each coating and drying, the cumulative dry adhesive amount A after that coating is determined using test samples prepared simultaneously in the same batch. i 180° peel force F i and breathability P i And calculate the coating balance coefficient K after the i-th coating. i ; ; Where i is an integer from 2 to 5; Fᵢ is the 180° peel force measured after the i-th coating and drying, in N / 24mm; Pᵢ is the air permeability after the i-th coating and drying, in L / (m²). 2 •s); P0 is the initial air permeability of the release fabric substrate before coating, in L / (m²). 2 ·s); Aᵢ represents the cumulative dry adhesive amount after the i-th coating and drying, in g / m³. 2 ; The coating result after the i-th coating and the coating result after the (i-1)-th coating satisfy the following relationship: ; ; ; ; S6: A release paper protective layer is attached to the outside of the adhesive layer, and after slitting and winding, a single-sided adhesive release cloth for wind turbine blade forming is obtained. The final dry adhesive weight A of the adhesive layer is 8-24 g / m³. 2 The thickness is 8-38μm, and the 180° peel force of the single-sided adhesive release cloth is 4.8-12N / 24mm.

[0008] This invention involves applying and drying the modified acrylic pressure-sensitive adhesive 2 to 5 times on the same adhesive side of the release fabric substrate, gradually forming an adhesive layer on the substrate surface. Each drying process after coating transforms the introduced adhesive into a relatively stable dry pressure-sensitive adhesive layer. During subsequent coatings, the newly added adhesive continues to spread and form a film under the combined action of the existing dry adhesive layer and the porous structure of the fabric surface. This results in an adhesive layer that is more likely to maintain uniformity in both the thickness and in-plane directions. The surface continuity, effective adhesion area, and bonding state with the release fabric substrate are gradually established, providing a stable surface positioning foundation for subsequent mold bonding.

[0009] In this process, the initial air permeability P0 first characterizes the pore opening state of the release fabric substrate before coating. After each coating and drying, the cumulative dry adhesive amount A is measured using test samples prepared simultaneously in the same batch. i 180° peel force F i and breathability P i A i F reflects the cumulative load level of the adhesive layer. i P reflects the adhesion and positioning ability after the adhesive layer is formed. i This reflects the retention status of the fabric's pore channels after coating. The three parameters correspond to the amount, force, and porosity of the adhesive layer, respectively, making them straightforward to use and providing a clearer view of the adhesive layer formation process. The 180° peel force was measured using ISO29862-2018 Method 1.

[0010] Secondly, the adhesive layer in wind turbine blade molding scenarios needs to simultaneously meet three conditions: first, it must have sufficient mold-side positioning capability; second, it must maintain necessary ventilation channels in the release fabric substrate; and third, it must avoid achieving apparent adhesion through excessive adhesive application. Therefore, by setting a coating balance coefficient K... i To control the state of adhesive layer formation. F i The 180° peel force corresponding to the i-th coating reflects the positioning ability after the adhesive layer is formed, and therefore serves as a positive contribution; P i / P0 corresponds to the ratio of the air permeability after coating to the initial air permeability, which reflects the retention state of the fabric's pore channels and also serves as a positive contribution; A i The cumulative dry adhesive amount reflects the adhesive layer load level. While increasing the adhesive amount helps form an adhesive surface, it also increases adhesive layer thickness, pore masking, and the risk of residual adhesive. Therefore, it is placed as a constraint term in the denominator. The resulting K... i It can characterize the effective positioning ability formed by a unit amount of dry adhesive while maintaining the air permeability channel.

[0011] This parametric relationship allows for the evaluation of adhesive layer adhesion benefits, porosity retention, and adhesive load in a unified manner. When initial coating increases the continuity of the adhesive surface, F... i Increase and P i / P0 remains high, K i Consequently, the amount of additional adhesive increases; as coating continues, the additional amount of adhesive affects F. i The contribution of A gradually slowed down, while A i Continue to increase, P i / P0 gradually decreases, K i The growth rate also decreases accordingly. By observing the growth rate of K value in the i-th and (i-1)-th iterations, it can be determined whether the increased amount of adhesive is still mainly converted into effective positioning ability. Let K... i The growth rate was limited to 0-12%, ensuring that the adhesive layer formation endpoint corresponded to a state where positioning efficiency stabilized and porosity remained within a controlled range. This indicated that the effect of the increased adhesive amount on overall positioning efficiency had plateaued. At this point, the adhesive layer had formed a sufficiently effective adhesive surface, and P... i / P0 is still limited to 0.72-0.95, indicating that the release fabric substrate still retains the necessary air permeability channels. This termination comparison relationship controls the film formation process of the adhesive layer at a stage where the positioning effect is stable and the air permeability is still controlled, so that the final adhesive layer has both the adhesion foundation required for molding and maintains the open pore state suitable for the use of the release fabric.

[0012] F i Relative to F i-1 The growth rate of Fᵢ is limited to 0.03–0.3, ensuring that the final effective coating still provides a identifiable increase in positioning force, while keeping the increase within a moderate range. For the curvature, slope, and vertical surfaces of wind turbine blade molds, the adhesive layer needs to provide stable but not excessively strong temporary adhesion. By controlling the growth rate of Fᵢ, the positioning capability of the adhesive layer can gradually enter a range suitable for the laying operation, making it easier for the release fabric to maintain its position during the laying process and reducing local slippage, curling, and wrinkling.

[0013] A i Compared to A i-1 The increase in dry adhesive is limited to 0.02–0.35, keeping the amount of dry adhesive added each time within a controllable range. This prevents the adhesive layer from piling up too thickly all at once, instead allowing it to gradually form a stable structure layer by layer after each drying cycle. This controlled increase in dry adhesive helps to ensure the adhesive layer spreads evenly on the adhesive side of the release fabric, and allows the adhesive layer thickness to gradually reach the range of 8–38 μm, thus creating an adhesive layer thickness and surface condition suitable for temporary positioning.

[0014] A when the terminating comparison relation is satisfied i F i and P iThese are used as the final dry adhesive amount, final 180° peel strength, and post-coating air permeability, respectively, to ensure that the final product state corresponds to the dynamic changes during the coating process. The final dry adhesive amount A is controlled at 8–24 g / m³. 2 The adhesive layer thickness is controlled at 8–38 μm, and the 180° peel force is controlled at 4.8–12 N / 24 mm. These final parameters collectively define the usage state of the adhesive layer: the dry adhesive amount is sufficient to support the formation of the surface adhesive layer, the adhesive layer thickness is suitable for forming a continuous positioning interface on one side of the release cloth, and the peel force falls within the range that coordinates temporary fixation and subsequent peeling.

[0015] In the process of wind turbine blade molding, after the release paper protective layer of this single-sided adhesive release fabric is removed, the adhesive layer can adhere to the mold surface. Because the adhesive layer undergoes multiple coatings, multiple drying processes, and controlled termination, the coated side exhibits stable adhesive continuity and a moderate 180° peel force. Therefore, the material adheres more easily to the mold surface during layup, making it particularly suitable for positioning and laying on large curved, inclined, and vertical surfaces. This positioning function helps the release fabric maintain its predetermined position during subsequent layup, vacuuming, and resin infusion processes, thereby improving the smoothness of the blade molding surface.

[0016] During the resin curing and peeling stages, the final dry glue amount, glue layer thickness, and air permeability retention rate of the adhesive layer are all within controlled ranges. The adhesive layer mainly serves as a temporary positioning element on the mold side. This adhesive layer condition helps reduce the risk of excessive flow and migration to the resin contact side under curing conditions, and is beneficial for maintaining a clean part surface after peeling, reducing residual glue, local contamination, and subsequent surface treatment work.

[0017] As a further improvement of the present invention, the warp density of the release fabric substrate is 14-25 threads / cm, the weft density is 14-25 threads / cm, and the unit area mass is 80-110g / m². 2 The thickness is 130–210 μm, and the initial air permeability P0 is 120–650 L / (m²). 2 The initial air permeability P0 was measured under a pressure difference of 100 Pa (·s).

[0018] By employing the aforementioned parameters for the release fabric substrate, a relatively stable structural foundation is formed in the plain weave substrate, considering yarn support, areal density load-bearing capacity, thickness buffering, and initial breathability. The interlacing state of the warp and weft yarns provides a more uniform adhesive-bearing surface on the coating side, making it easier for the modified acrylic pressure-sensitive adhesive to spread and form a film along the substrate surface during subsequent layering. The unit area mass and thickness provide necessary solid support and thickness direction buffering for the adhesive layer formation, ensuring that the adhesive layer can be stably retained in the coating side surface area after layering and maintaining the substrate's flexibility suitable for curvature surface application in wind turbine blade molds.

[0019] The initial air permeability P0 serves as the benchmark for subsequent calculations of Pᵢ / P0 and Kᵢ, fixing the pore opening state of the substrate before coating within an evaluable range. This allows for a more accurate reflection of the adhesive layer's influence on the fabric's pore channels after each coating, rather than being affected by excessive differences in the substrate's initial porosity. By jointly defining the substrate geometry and the initial air permeability state, the Pᵢ in the subsequent coating balance coefficient... i / P0 provides a stable basis for comparison, and also allows for a clearer correspondence between the adhesive film formation process and the substrate pore structure.

[0020] As a further improvement of the present invention, in step S1, the warp tension is controlled to be 18-35N and the weft tension to be 10-26N during weaving; during cleaning, the plain weave fabric is treated in a water bath at 40-60℃ for 2-8 minutes, and the moisture is removed under the condition of a liquid-pinching rate of 45%-75%; the heat setting temperature is 150-190℃, the heat setting time is 30-90s, and the longitudinal overfeed rate and the transverse stretching rate are controlled to be 0%-3% and 0%-4% respectively during the heat setting process.

[0021] By controlling the weaving tension, washing state, and heat setting state of the plain weave fabric, the release fabric substrate can achieve a relatively stable yarn arrangement, a clean adhesive-coated side surface, and a repeatable open pore state before entering the coating process. After the warp and weft yarns complete interlacing under appropriate tension, the interlacing points in the plain weave structure are more evenly distributed, and a continuous fiber support network is formed on the adhesive-coated side surface, providing a more uniform bonding surface for the subsequent spreading of the modified acrylic pressure-sensitive adhesive. In this way, the adhesive can form a continuous initial adhesive surface along the yarn surface and the shallow area between the yarns during the first coating, laying the foundation for the layer-by-layer film formation in subsequent coating processes.

[0022] As a further improvement of the present invention, the modified acrylic pressure-sensitive adhesive in step S3 has a coating viscosity of 800-3500 mPa·s, a solid content of 38%-58%, and a coating gap of 15-80 μm; after the modified acrylic pressure-sensitive adhesive is coated on one side of the release cloth substrate, it is subjected to a pressing process to form a single-coated adhesive layer. The pressing process has a pressure of 0.10-0.45 MPa, a temperature of 35-70°C, and a speed of 3-18 m / min.

[0023] Coating viscosity and solid content together determine the fluidity, spreadability, and residual adhesive amount after drying of the adhesive during the coating process. When the viscosity is within a suitable range, the adhesive can spread evenly along the yarn surface and shallow pore areas on the coated side, forming a continuous but not excessively accumulated wet film. When the solid content is within a suitable range, there is a relatively stable correlation between the amount of dry adhesive formed after a single coating and the thickness of the wet film, ensuring a stable A after each coating. iIt can gradually increase as expected. By matching the coating viscosity and solid content, the adhesive layer formed by a single coating has both sufficient film-forming material basis and maintains good coating uniformity, thus making the cumulative dry adhesive amount change more controllable in multiple coating processes.

[0024] The coating gap is used to control the wet film thickness of the adhesive in a single coating. The coating gap, in conjunction with the adhesive viscosity and solids content, ensures that the amount of new adhesive added in each coating falls within a relatively stable range. Thus, after each coating, A... i Compared to A i-1 The growth rate is more easily kept within the set range. This control allows the adhesive layer to form gradually in a progressive manner, with the thin layer after each drying providing a substrate for the next coating. The next coating further supplements the surface continuity and effective adhesion area, thereby making the thickness and in-plane distribution of the adhesive layer more stable.

[0025] The pressing pressure and temperature primarily affect the adhesion between the adhesive layer and the coated side of the release fabric substrate. When the pressing pressure is within a suitable range, the adhesive liquid or semi-dry adhesive layer can make sufficient contact with the yarn surface, allowing the adhesive layer to form a stable adhesion on the coated side. When the pressing temperature is within a suitable range, the modified acrylic pressure-sensitive adhesive has appropriate interfacial wetting ability and initial adhesion state, facilitating the adhesion of the adhesive layer to the substrate surface. Through the combination of pressing pressure and pressing temperature, the adhesive layer can form a stable surface bonding interface on the coated side, providing an interfacial basis for the subsequent gradual increase of the 180° peel force Fᵢ.

[0026] The pressing speed regulates the coating dwell time, pressure time, and adhesive surface condition. When the pressing speed is stable, the process from coating and bonding to drying of the adhesive is consistent, resulting in smaller thickness fluctuations in both the width and length directions of the adhesive layer. This makes it easier for test samples prepared simultaneously in the same batch to maintain a consistent coating state with the actual product. i F i and P i The test results can better reflect the state of adhesive layer formation in actual production.

[0027] As a further improvement of the present invention, in step S4, the cumulative dry adhesive amount A1 after the first coating is 35% to 60% of the final dry adhesive amount A; the additional dry adhesive amount of the i-th coating relative to the (i-1)-th coating is 1.0 to 6.0 g / m³. 2 The interval between two consecutive coatings is 2 to 20 minutes.

[0028] The cumulative dry adhesive amount after the first coating accounts for 35% to 60% of the final dry adhesive amount, providing a sufficient film-forming foundation for the initial adhesive layer. Once formed, this initial adhesive layer can establish stable contact with the adhesive-coated yarn surface of the release liner substrate, and also provides a relatively continuous interface for subsequent coatings. This makes it easier for newly applied adhesive to spread along the existing adhesive layer surface, gradually improving the continuity within the adhesive layer. i It will also gradually increase as the effective adhesion area increases.

[0029] The significance of this initial dry adhesive ratio lies in ensuring that the first coat establishes a stable adhesive base while allowing room for subsequent adjustments. If the initial adhesive layer formed by the first coat is too thin, the continuity of the adhesive layer will be established more slowly in subsequent coats. i The improvement is not stable enough; if the initial adhesive surface formed by the first coating is too thick, subsequent coatings will result in instability. i The adjustment space will shrink, P i / P0 also tends to decrease earlier. Through the above ratio control, the first coating can serve as the substrate for film formation, while subsequent coatings serve as fine-tuning agents.

[0030] The amount of additional dry adhesive applied in the i-th coating compared to the (i-1)-th coating is controlled between 1.0 and 6.0 g / m². 2 This allows for a clear hierarchical progression in the amount of adhesive added each time. When the amount of new dry adhesive is within this range, each coat not only has a detectable impact on the continuity and positioning ability of the adhesive layer, but also allows Aᵢ to accumulate gradually. Thus, F after each coat... i A i and P i A relatively clear correspondence will be formed between them, making it easier to use K i Determine the effective positioning benefits brought about by the increase in adhesive volume.

[0031] This newly added dry adhesive quantity range is an important process basis supporting the termination comparison relationship. Because K i It needs to reflect the positioning ability formed by a unit amount of dry adhesive while maintaining air permeability. If the amount of adhesive added each time fluctuates too much, K i Changes in K are easily affected by sudden changes in the amount of glue applied in a single application; by limiting the amount of new dry glue to a stable range, K i The increase in the coating amount more accurately reflects the changes in the film-forming state of the adhesive layer, rather than simply reflecting drastic changes in the amount of coating applied in a single application.

[0032] Setting an interval of 2–20 minutes between two consecutive coatings allows the dry pressure-sensitive adhesive layer after the previous coating to complete the necessary surface stabilization and internal solvent release. This interval ensures that the previous adhesive layer has a good support state before subsequent coatings, allowing the subsequent adhesive to spread and form a continuous bond with the existing adhesive layer while maintaining interlayer fusion. In this way, the adhesive layer formed by multiple coatings does not exhibit a fragmented multilayer structure, but rather forms a continuous, integral pressure-sensitive adhesive layer.

[0033] This interval also allows for better process consistency in the test results after each coating. The next coating is applied only after the previous adhesive layer has stabilized. i Corresponding cumulative dry adhesive amount, F i Corresponding positioning capabilities, P i The corresponding changes in air permeability more readily reflect the true film-forming state after the coating. Therefore, the changes in K between the two coating processes are more consistent. i The changes can more accurately characterize the process of the adhesive layer transitioning from the effective tackification stage to the balanced film formation stage.

[0034] As a further improvement of the present invention, the drying after each coating includes a first drying section and a second drying section. The temperature of the first drying section is 65-85°C and the time is 0.5-2.0 min. The temperature of the second drying section is 85-115°C and the time is 1.0-4.0 min. The drying after the last coating also includes a film stabilization drying section. The temperature of the film stabilization drying section is 100-125°C and the time is 2-8 min.

[0035] By implementing a segmented drying process, the modified acrylic pressure-sensitive adhesive is gradually transformed from a wet film to a dry pressure-sensitive adhesive layer after each coating, with further film stabilization treatment completed after the final coating. This drying method does more than simply remove moisture or solvents; it ensures an orderly process of evaporation, spreading, film formation, and interfacial stabilization, providing a stable adhesive layer state for subsequent coatings and final molding applications.

[0036] The first drying stage employs a relatively mild temperature and short time, primarily to allow the coated wet adhesive film to complete surface leveling and initial evaporation. During this stage, the adhesive still retains some spreading ability, allowing it to continue to distribute evenly along the yarn surface and shallow areas of the adhesive-coated side of the release fabric substrate, resulting in a more gradual thickness of the adhesive layer formed in a single coating. This stage facilitates the formation of a continuous and uniform initial adhesive film, providing a smooth surface base for subsequent drying and the next coating.

[0037] The temperature is further increased in the second drying stage, primarily to promote the continued release of volatile components within the adhesive layer, transitioning it from a preliminary leveled state to a dry pressure-sensitive adhesive state. After this stage, the adhesive layer exhibits a more stable morphology and cohesive state, allowing it to absorb additional adhesive in the next coating. Thus, the adhesive layer formed after each coating is not a loose, wet film, but rather a dry thin layer with a certain surface strength and interfacial stability. This dry thin layer can play a supporting and regulating role in subsequent coatings, allowing more of the additional adhesive to participate in the continuity of the surface adhesive layer, while maintaining controllable changes in the overall thickness and permeability of the adhesive layer.

[0038] A film-stabilizing drying section is set up after the final coating. Its function is to further stabilize the cohesive structure and surface pressure-sensitive state of the final adhesive layer. After the previous coatings, the adhesive layer has formed a cumulative dry adhesive amount and an effective adhesion interface; the film-stabilizing drying section further releases the volatile components in the final adhesive layer, and the surface adhesion and internal cohesive strength of the adhesive layer tend to be in harmony. This treatment helps to stabilize the final 180° peel force within the range required for temporary positioning, and to maintain a relatively stable interface state of the adhesive layer during subsequent winding, storage, laying, and curing.

[0039] Segmented drying is also directly related to A i F i P i and K i The reliability of the test. After each coating, if the adhesive layer has not yet reached a stable dry state, A i Corresponding dry glue amount, F i The corresponding peeling force and P i The corresponding air permeability is affected by residual volatile components in the adhesive layer and fluctuations in surface condition. Through continuous processing in the first and second drying stages, the adhesive layer condition before each test is more consistent. i F i and P i The relationship between them is also clearer. Thus, K i The positioning ability that combines breathability and positioning under a unit dry adhesive amount better corresponds to the actual film-forming state of the adhesive layer.

[0040] As a further improvement of the present invention, the modified acrylic pressure-sensitive adhesive includes an acrylate copolymer, a heat-resistant cohesive reinforcing component, and a polar anchoring component; Based on the total dry mass of the modified acrylic pressure-sensitive adhesive, the acrylate copolymer accounts for 82% to 96%, the heat-resistant cohesive reinforcing component accounts for 2% to 10%, and the polar anchoring component accounts for 1% to 8%. The glass transition temperature of the acrylate copolymer is -35℃ to -10℃, and the gel content of the adhesive layer formed by the modified acrylic pressure-sensitive adhesive is 45% to 78%.

[0041] By limiting the modified acrylic pressure-sensitive adhesive to consist of acrylate copolymers, heat-resistant cohesive reinforcing components, and polar anchoring components, and further limiting the dry adhesive mass ratio, glass transition temperature, and gel content of each component, a more stable material base can be formed between pressure-sensitive adhesion, heat-resistant cohesion, and substrate bonding. This supports the stability of film formation after multiple coatings, the morphology retention during the thermosetting process, and the overall removal with the release cloth during the peeling stage.

[0042] The acrylate copolymer serves as the main film-forming component, providing the adhesive layer with flexibility, wettability, and initial adhesion properties. Its glass transition temperature is controlled within a low range, allowing the adhesive layer to remain moderately soft during room-temperature application, adapting to local undulations in curved, inclined, or vertical areas of wind turbine blade molds. Furthermore, with the increase in multiple coating layers and adhesive surface continuity, the 180° peel strength gradually improves.

[0043] Heat-resistant cohesive reinforcing components are used to improve the internal structural stability of the adhesive layer. Through physical entanglement, polar action, or mild cross-linking, the adhesive layer maintains high cohesive strength during staged drying, vacuum infusion, and thermosetting, reducing thermal flow and local transfer. This makes the adhesive layer easier to detach from the release cloth as a whole during peeling, thereby reducing the risk of residual adhesive.

[0044] The polar anchoring component primarily enhances the interfacial bonding between the adhesive layer and the adhesive-coated side of the release fabric substrate. Its amide, hydroxyl, or carboxyl groups can form hydrogen bonds, dipole interactions, or polar adsorption with the surface of nylon or polyester filaments, ensuring that the adhesive layer remains stably on the substrate side after multiple coatings and drying, reducing the risk of residual adhesive and contamination on the part side.

[0045] The proportions of the three components are carefully controlled to ensure coordination in film formation, cohesive reinforcement, and polar anchoring: the acrylate copolymer guarantees continuous film formation and pressure-sensitive adhesion; the heat-resistant cohesive reinforcement component improves thermal stability and cohesive strength; and the polar anchoring component enhances fiber surface bonding and maintains the flexibility of the adhesive layer. The gel content of the adhesive layer is controlled between 45% and 78%, further limiting the degree of the internal network structure of the adhesive layer, enabling it to maintain pressure-sensitive adhesion at room temperature and possess good shape retention under heated conditions.

[0046] As a further improvement of the present invention, there exists at least one instance where the coating result after the j-th coating and the coating result after the (j-1)-th coating satisfy the following relationship: ; ; ; Where j is an integer from 2 to 4, and j < i.

[0047] By incorporating at least one significant tackification stage before the termination comparison relationship is reached, the multi-coating process can exhibit a continuous path of change from initial film formation, effective tackification, to equilibrium film formation. The formation of the adhesive layer further demonstrates, through the staged changes during the coating process, that the adhesive layer indeed undergoes a gradual establishment of an effective adhesion interface.

[0048] In the initial stage of multiple coating processes, the continuity of the adhesive surface on the coated side of the release liner substrate is still being established. At this time, the additional adhesive is mainly used to fill the tiny gaps on the surface of the yarns on the coated side, improve the continuity of the adhesive surface, and increase the effective adhesive surface that can adhere to the mold surface. Accordingly, F j A significant improvement will occur, K j This will also increase. By limiting the termination comparison relation to at least one K, j Growth rate greater than 12%, F j A growth rate greater than 0.25 indicates that the initial stage of the multi-coating process is indeed in an effective tack-enhancing phase, with the increased adhesive amount mainly contributing to improved adhesive surface continuity and positioning capabilities.

[0049] P is simultaneously limited in this stage. j A P0 value between 0.72 and 0.98 indicates that during the effective tackification stage, although the adhesive layer has begun to form a relatively significant positioning ability, the air permeability channels of the release fabric substrate remain within a suitable range. In other words, the improved film formation and positioning ability of the adhesive layer on the coated surface are coordinated with the preservation of the fabric's pore structure. This limitation ensures that the early effective tackification stage is not only characterized by improved peel force but also by improved positioning ability under controllable air permeability conditions.

[0050] As subsequent coating processes continue, the surface film of the adhesive layer gradually stabilizes, and the amount of newly added adhesive has an impact on F. i and K i The rate of increase gradually plateaus. The initial significant increase in viscosity and the subsequent termination phase together constitute a continuous coating control logic. In the initial stage, the significant increase in F₼ and K₼ gradually establishes effective adhesive surface, surface bonding, and positioning capabilities on the adhesive side of the release fabric. In the later stage, the increase in Kᵢ enters the termination comparison range, identifying the film-forming state where the adhesive layer's positioning efficiency tends to stabilize. The two stages are interconnected, ensuring that the judgment to stop coating is based on the trend of adhesive layer film formation changes, rather than a single final value.

[0051] The resulting adhesive layer has a stable and appropriate temporary positioning interface on the adhesive side, which can support the laying and positioning of curved, inclined and vertical mold surfaces, and keep the ventilation channels and dry adhesive amount under control, thus facilitating interface stability during subsequent laying, vacuum infusion, thermosetting and peeling processes.

[0052] The second aspect of the present invention provides a single-sided adhesive release fabric prepared by the method described above for forming a single-sided adhesive release fabric for wind turbine blades, wherein the single-sided adhesive release fabric includes a release fabric substrate, an adhesive layer disposed on one side of the release fabric substrate, and a release paper protective layer adhered to the outside of the adhesive layer. The adhesive layer is a modified acrylic pressure-sensitive adhesive layer, and the final dry adhesive weight of the adhesive layer is 8-24 g / m³. 2 The thickness is 8–38 μm; The 180° peel force of the single-sided adhesive release cloth is 4.8-12 N / 24 mm, and the ratio of the air permeability after coating to the initial air permeability of the release cloth substrate before coating is 0.72-0.95.

[0053] As a further improvement of the present invention, after the single-sided adhesive release cloth is peeled off from the cured epoxy resin board, the amount of residual adhesive on the surface of the cured epoxy resin board is no more than 0.8 mg / 100 cm². 2 .

[0054] The controlled amount of residual adhesive on the surface of the cured epoxy resin board indicates that the adhesive layer can be effectively removed with the release cloth during peeling. Therefore, this single-sided adhesive release cloth can balance mold positioning, curing stability, and peeling cleanliness, which is beneficial for maintaining the flatness and cleanliness of the wind turbine blade surface.

[0055] The present invention, by adopting the above technical solution, has the following beneficial effects: 1. By employing multi-coating, multi-drying, and termination comparison control, the modified acrylic pressure-sensitive adhesive gradually forms an adhesive layer on the same coated side of the release fabric substrate. This process links the cumulative dry adhesive amount Aᵢ, 180° peel force Fᵢ, and air permeability Pᵢ, and uses the coating balance coefficient Kᵢ to determine the film-forming state of the adhesive layer, ensuring that the point of stopping coating matches the adhesive layer's positioning ability, adhesive load, and porosity retention. The resulting adhesive layer exhibits relatively stable surface continuity and moderate temporary adhesion, providing stable positioning for the application of adhesive to curved, inclined, and vertical areas of wind turbine blade molds.

[0056] 2. By controlling the weaving, cleaning, and heat-setting processes of the release fabric substrate, as well as its initial air permeability P0 before coating, the substrate achieves stable yarn support, a clean surface, and open pores before adhesive application. This substrate condition provides a reliable basis for subsequent Pᵢ / P0 and Kᵢ evaluations, allowing the increase in dry adhesive amount, peel strength, and air permeability after each coating to more accurately reflect the adhesive layer formation process. Combined with control over coating viscosity, solid content, coating gap, drying conditions, and adhesive layer material composition, the adhesive layer can form a uniform, continuous, and non-overly pore-sealing positioning interface on the coating side.

[0057] 3. The final dry adhesive amount, adhesive layer thickness, 180° peel force, and post-coating air permeability retention rate of the obtained single-sided adhesive release fabric are within a suitable range, ensuring that the adhesive layer has both the ability to position the mold and retains the necessary pore channels of the release fabric substrate. Under high-temperature vacuum curing conditions, the peel force and air permeability of the adhesive layer remain stable, and the amount of residual adhesive on the surface of the cured epoxy resin after peeling is controlled. Therefore, this single-sided adhesive release fabric can balance stable laying, stable interface during curing, and clean surface after peeling, which is beneficial for reducing wrinkles, residual adhesive, and subsequent cleaning of wind turbine blade components. Attached Figure Description

[0058] Figure 1 The original test curve of 180° peel force of the single-sided adhesive release fabric obtained in Example 1 after high temperature vacuum treatment.

[0059] Figure 2 The original test curve of 180° peel force of the single-sided adhesive release cloth obtained in Comparative Example 2 after high temperature vacuum treatment. Detailed Implementation

[0060] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0061] Unless otherwise defined, all scientific and technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art.

[0062] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0063] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0064] The present invention will now be described in detail with reference to specific embodiments, which are intended to understand rather than limit the invention.

[0065] Example 1 This embodiment discloses a method for preparing a single-sided adhesive release fabric for wind turbine blade molding, and obtains a single-sided adhesive release fabric for wind turbine blade molding by the method. The single-sided adhesive release fabric includes a release fabric substrate, an adhesive layer disposed on one side of the release fabric substrate, and a release paper protective layer adhered to the outside of the adhesive layer.

[0066] The release fabric substrate is made of nylon 66 filament. The nylon 66 filament has the following specifications: 233DTex / 36f, breaking strength 7.1cN / dtex, dry heat shrinkage rate 3.8% (177℃*2min), and oil content 0.4%. Both the warp and weft yarns are made of the aforementioned nylon 66 filament.

[0067] The cleaning solution is composed of deionized water and a fatty alcohol polyoxyethylene ether type nonionic surfactant, wherein the mass concentration of the fatty alcohol polyoxyethylene ether type nonionic surfactant in the cleaning solution is 0.8 g / L.

[0068] The modified acrylic pressure-sensitive adhesive, based on 100 parts by total dry adhesive weight, comprises the following components: 90 parts of acrylate copolymer; Six parts of epoxy-modified acrylate oligomer; Four parts of acrylamide-hydroxyethyl acrylate copolymer.

[0069] The acrylate copolymer is formed by copolymerizing butyl acrylate, isooctyl acrylate, methyl methacrylate, acrylic acid, and hydroxyethyl acrylate. Based on the total mass of the monomers in the acrylate copolymer, butyl acrylate accounts for 54 parts, isooctyl acrylate for 28 parts, methyl methacrylate for 10 parts, acrylic acid for 4 parts, and hydroxyethyl acrylate for 4 parts. The glass transition temperature of the acrylate copolymer is -24℃.

[0070] Epoxy-modified acrylate oligomers, used as heat-resistant cohesive reinforcing components, have an epoxy equivalent of 450 g / eq, a number-average molecular weight of 1800, and a viscosity of 3500 mPa·s at 25°C.

[0071] The acrylamide-hydroxyethyl acrylate copolymer is formed by copolymerizing acrylamide and hydroxyethyl acrylate in a mass ratio of 75:25, and has a number average molecular weight of 9500.

[0072] The above three types of dry adhesive components were added to deionized water, and the pH of the system was adjusted to 7.8 using ammonia. After stirring for 30 minutes, a modified acrylic pressure-sensitive adhesive was obtained. The modified acrylic pressure-sensitive adhesive had a solid content of 48.0% and a viscosity of 1800 mPa·s at 25°C. Before coating, the modified acrylic pressure-sensitive adhesive was filtered through a 100-mesh filter and allowed to stand for 30 minutes to remove bubbles.

[0073] The release paper protective layer uses single-sided silicone release paper with a basis weight of 80g / m³. 2 It has a thickness of 95μm and the release surface faces the adhesive layer.

[0074] The specific preparation method of single-sided adhesive release fabric is as follows: S1: Preparation of release fabric substrate Nylon 66 filaments were sequentially warped, threaded, and woven to create a plain weave fabric. During weaving, the warp tension was controlled at 26N, and the weft tension at 18N. The resulting plain weave fabric had a warp density of 16 threads / cm and a weft density of 16 threads / cm.

[0075] The plain-patterned billet was placed in a 50°C cleaning solution for 5 minutes with a bath ratio of 1:20. After cleaning, it was rinsed with deionized water for 2 minutes, and then the water was removed by rolling with a rolling mill. The rolling liquid ratio was controlled at 60%.

[0076] The cleaned plain weave fabric was heat-set at a temperature of 175℃ for 60 seconds. During the heat-setting process, the longitudinal overfeed rate was 1.5% and the transverse stretching rate was 2.0%, resulting in a release fabric substrate.

[0077] The resulting release fabric substrate has a unit area mass of 85 g / m². 2 The thickness is 161μm.

[0078] S2: Measure the initial air permeability P0 Five test samples were cut from the release fabric substrate obtained in step S1, each measuring 200mm × 200mm. The air permeability was measured using a pressure difference of 100Pa. The average value of the five test samples was taken as the initial air permeability P0 of the release fabric substrate before coating. In this embodiment, P0 is 360L / (m²). 2 ·s).

[0079] During the multi-coating process, the cumulative dry adhesive amount A after each coating was determined using test samples prepared simultaneously in the same batch. i 180° peel force F i and breathability P i The test sample and the officially prepared single-sided adhesive release fabric were prepared using the same release fabric substrate, the same modified acrylic pressure-sensitive adhesive, the same coating parameters, and the same drying conditions. The test sample was used for process testing, while the officially prepared single-sided adhesive release fabric itself was not subjected to destructive peel testing.

[0080] Cumulative dry adhesive quantity A i The determination was performed as follows: A 100cm² area was cut from the test sample before the i-th coating. 2 The substrate sample is taken and weighed, and recorded as m0; after the i-th coating and drying, a sample with adhesive of the same area is cut and weighed, and recorded as m. i ; Calculate the cumulative dry adhesive amount A after the i-th coating based on the mass difference per unit area. i A i The unit is g / m 2 .

[0081] The 180° peel strength Fᵢ was determined as follows: After the i-th coating and drying, the test sample was cut into strips with a width of 24 mm and a length of 300 mm. The adhesive layer was attached to the surface of the epoxy mold gel coat plate, and a 2 kg roller was used to roll it back and forth twice at 10 mm / s. The sample was then placed at 23°C and 50% relative humidity for 30 min. Subsequently, Fᵢ was obtained by testing according to ISO29862-2018 Method 1, with the unit being N / 24 mm.

[0082] Breathability P i The following method was used for measurement: A fabric air permeability tester was used for testing, with a test pressure difference of 100 Pa. The initial air permeability P0 of the release fabric substrate was measured before coating; after the i-th coating and drying, the air permeability P of the test samples prepared simultaneously in the same batch was measured. i Air permeability retention rate is calculated based on P. i / P0 calculation.

[0083] The coating balance coefficient K after the i-th coating is i Calculate using the following formula:

[0084] Where i is an integer from 2 to 5; Fᵢ is the 180° peel force measured after the i-th coating and drying, in N / 24mm; P i The air permeability after the i-th coating and drying is expressed in L / (m²). 2 •s); P0 is the initial air permeability of the release fabric substrate before coating, in L / (m²). 2 ·s); A i This represents the cumulative dry adhesive weight after the i-th coating and drying, expressed in g / m³. 2 .

[0085] S3: Perform the first coating and dry. Place the release fabric substrate from step S2 onto the coating equipment with the adhesive-coated side facing upwards. Apply the modified acrylic pressure-sensitive adhesive to one side of the release fabric substrate using a comma-shaped doctor blade coating method. The coating line speed is 8 m / min, the coating gap is 38 μm, and the single wet coating amount is 11.5 g / m². 2 .

[0086] After the first coating, the coated release fabric substrate is passed sequentially through the first drying section and the second drying section. The temperature of the first drying section is 75℃ and the drying time is 1.2 min; the temperature of the second drying section is 100℃ and the drying time is 2.5 min, thus completing the first coating and drying.

[0087] The cumulative dry adhesive content (A1) after the first coating was 5.5 g / m², measured using test samples prepared simultaneously in the same batch. 2The 180° peel force F1 is 3.6 N / 24mm, and the air permeability P1 is 342L / (m²). 2 ·s). The coating balance coefficient K1 after the first coating is calculated to be 0.622.

[0088] S4: Apply the second coat and dry. A second coating was applied to the same adhesive-coated side of the release fabric substrate after the first coating and drying. The interval between two consecutive coatings was 8 minutes. The second coating used the same modified acrylic pressure-sensitive adhesive as the first coating, with a coating line speed of 8 m / min, a coating gap of 30 μm, and a single wet coating weight of 8.3 g / m². 2 .

[0089] After the second coating, the coated release fabric substrate is passed sequentially through the first drying section and the second drying section. The temperature of the first drying section is 75℃, and the drying time is 1.2 min; the temperature of the second drying section is 100℃, and the drying time is 2.5 min, thus completing the second coating and drying.

[0090] The cumulative dry adhesive content (A2) after the second coating was measured using test samples prepared simultaneously in the same batch. 2 The 180° peel strength F2 is 7.8 N / 24 mm, and the air permeability P2 is 324 L / (m²). 2 ·s). The coating balance coefficient K2 after the second coating is 0.739.

[0091] The second coating increased K2 by 18.8% and F2 by 116.7% compared to the first coating, with P2 / P0 being 0.9.

[0092] S5: Perform the third coating, drying, and termination judgment. A third coating was applied to the same adhesive-coated side of the release fabric substrate after the second coating and drying. The interval between adjacent coatings was 8 minutes. The third coating used the same modified acrylic pressure-sensitive adhesive as the first coating, with a coating line speed of 8 m / min, a coating gap of 18 μm, and a single wet coating weight of 2.7 g / m². 2 .

[0093] After the third coating, the coated release fabric substrate is passed sequentially through the first drying section and the second drying section. The temperature in the first drying section is 75℃, and the drying time is 1.2 min; the temperature in the second drying section is 100℃, and the drying time is 2.5 min. Subsequently, film stabilization drying is performed at 112℃ for 5 min.

[0094] The cumulative dry adhesive content (A3) after the third coating was measured using test samples prepared simultaneously in the same batch. 2The 180° peel strength F3 is 9.7 N / 24 mm, and the air permeability P3 is 302 L / (m³). 2 (·s). The coating balance coefficient K3 after the third coating is 0.754.

[0095] The third coating showed a 2% increase in K3 compared to the second coating; the F3 showed a 24.4% increase; and the A3 showed a 13.7% increase. The P3 / P0 ratio is 0.839.

[0096] Therefore, the application of adhesive layers was stopped after the third coat. A3 at the end of the process is taken as the final dry adhesive amount A of the adhesive layer, F3 is taken as the 180° peel force of the single-sided adhesive release fabric, and P3 is taken as the air permeability of the single-sided adhesive release fabric after coating.

[0097] In this embodiment, the final dry adhesive weight A of the adhesive layer is 10.8 g / m³. 2 The average thickness of the adhesive layer measured on the coated side surface was 16 μm, the 180° peel force of the single-sided adhesive release cloth was 9.7 N / 24 mm, and the ratio of air permeability after coating to initial air permeability before coating was 0.839.

[0098] S6: Apply the release paper protective layer and wind up. The adhesive layer of the release cloth obtained in step S5 is bonded to the outside of a single-sided silicone release paper, with the release surface of the release paper facing the adhesive layer. The bonding pressure is 0.18 MPa, the bonding temperature is 35℃, and the bonding speed is 10 m / min.

[0099] After lamination, the composite material is cut into rolls with a width of 1.20m and a length of 100m, with a winding tension of 45N, to obtain a single-sided adhesive release cloth for wind turbine blade molding.

[0100] Example 2 This embodiment discloses a method for preparing a single-sided adhesive release fabric for wind turbine blade molding. The only difference from Embodiment 1 is that the release fabric substrate is made of polyester filament, and the specific process parameters and test data in the multi-coating process are different.

[0101] The polyester filament has a specification of 278DTex / 60f, a breaking strength of 7.8cN / dtex, a dry heat shrinkage rate of 2.6% (180℃*3min), and an oil content of 0.5%. Both the warp and weft yarns are made of the above-mentioned polyester filament.

[0102] The weaving and pretreatment processes for the release fabric substrate are as follows: warp tension is 24N, weft tension is 17N; plain weave fabric warp density is 16 threads / cm, weft density is 16 threads / cm; cleaning temperature is 50℃, cleaning time is 5min, and liquid extraction rate is 58%; heat setting temperature is 180℃, heat setting time is 55s, longitudinal overfeed rate is 1.0%, and transverse stretching rate is 1.8%. The resulting release fabric substrate has a unit area mass of 85g / m². 2 The thickness is 155μm, and the initial air permeability P0 is 420L / (m²). 2 ·s).

[0103] The modified acrylic pressure-sensitive adhesive has the same composition as in Example 1, with a viscosity of 1850 mPa·s and a solid content of 48.0% before coating. Three separate coatings and drying processes were performed on the same side of the release fabric substrate. The first drying stage was at 75°C for 1.2 min, the second drying stage was at 100°C for 2.5 min, and the third coating was followed by film stabilization drying at 112°C for 5 min.

[0104] The data for each coating are shown in Table 1 below: Table 1

[0105] Compared to the second coating, the third coating resulted in an increase of 1.1% in K3, 23.8% in F3, and 14.0% in A3. The P3 / P0 ratio was 0.838, satisfying the termination comparison condition. Therefore, the coating process was stopped after the third coating.

[0106] In this embodiment, the final dry adhesive weight of the adhesive layer is 11.4 g / m³. 2 The adhesive layer thickness is 17μm, the 180° peel strength is 9.9N / 24mm, and the ratio of air permeability after coating to initial air permeability is 0.838.

[0107] Example 3 This embodiment discloses a method for preparing a single-sided adhesive release fabric for wind turbine blade molding. The only difference from Embodiment 1 is that the release fabric substrate is made of nylon 6 filaments, and the coating is applied in four stages.

[0108] The nylon 6 filament has a specification of 233DTex / 36f, a breaking strength of 6.8cN / dtex, a dry heat shrinkage rate of 4.5% (180℃*3min), and an oil content of 0.6%. Both the warp and weft yarns are made of the aforementioned nylon 6 filament.

[0109] The weaving and pretreatment processes for the release fabric substrate are as follows: warp tension is 25N, weft tension is 17N; plain weave fabric warp density is 18 threads / cm, weft density is 18 threads / cm; cleaning temperature is 48℃, cleaning time is 6min, and liquid-pinching rate is 62%; heat setting temperature is 168℃, heat setting time is 70s, longitudinal overfeed rate is 2.0%, and transverse stretching rate is 2.5%. The resulting release fabric substrate has a unit area mass of 85g / m². 2 The thickness is 155μm, and the initial air permeability P0 is 300L / (m²). 2 ·s).

[0110] The modified acrylic pressure-sensitive adhesive has the same composition as in Example 1, with a viscosity of 1750 mPa·s and a solid content of 48.0% before coating. Four separate coatings and drying processes were performed on the same side of the release fabric substrate, followed by film stabilization and drying after the fourth coating.

[0111] The data for each coating are shown in Table 2 below: Table 2

[0112] Compared to the third coating, the fourth coating increases K4 by 1%, F4 by 14.3%, A4 by 10.0%, and P4 / P0 by 0.807, satisfying the termination comparison relationship. Therefore, the coating process is stopped after the fourth coating.

[0113] In this embodiment, the final dry adhesive weight of the adhesive layer is 14.3 g / m³. 2 The adhesive layer thickness is 22μm, the 180° peel force is 12N / 24mm, and the ratio of air permeability after coating to initial air permeability is 0.807.

[0114] Example 4 This embodiment discloses a method for preparing a single-sided adhesive release fabric for wind turbine blade molding. The only difference from Embodiment 1 is that the final dry adhesive content is increased, forming an adhesive layer with higher positioning force.

[0115] The release fabric substrate was woven using the same nylon 66 filament and plain weave method as in Example 1. The resulting release fabric substrate had a warp density of 16 threads / cm, a weft density of 16 threads / cm, and a unit area mass of 85 g / m². 2 The thickness is 161 μm, and the initial air permeability P0 is 360 L / (m²). 2 ·s).

[0116] The modified acrylic pressure-sensitive adhesive has the same composition as in Example 1, with a viscosity of 2000 mPa·s and a solid content of 48.0% before coating. Three separate coatings and drying processes were performed on the same side of the release fabric substrate, followed by film stabilization and drying after the third coating.

[0117] The data for each coating are shown in Table 3 below: Table 3

[0118] Compared to the second coating, the third coating increases K3 by 1.6%, F3 by 29.2%, and A3 by 18.6%, with P3 / P0 at 0.831, satisfying the termination comparison condition. Therefore, the coating process is stopped after the third coating.

[0119] In this embodiment, the final dry adhesive weight of the adhesive layer is 18.0 g / m³. 2 The adhesive layer thickness is 25μm, the 180° peel force is 11.5N / 24mm, and the ratio of air permeability after coating to initial air permeability is 0.831.

[0120] Example 5 This embodiment discloses a method for preparing a single-sided adhesive release fabric for wind turbine blade molding. The only difference from Example 1 is that the proportion of heat-resistant cohesive reinforcing components in the modified acrylic pressure-sensitive adhesive is increased.

[0121] The modified acrylic pressure-sensitive adhesive, based on 100 parts by total dry adhesive weight, comprises the following components: 87 parts of acrylate copolymer; 9 parts of epoxy-modified acrylate oligomer; Four parts of acrylamide-hydroxyethyl acrylate copolymer.

[0122] The monomer composition of the acrylate copolymer was the same as in Example 1, with a glass transition temperature of -24°C. The epoxy equivalent of the epoxy-modified acrylate oligomer was 450 g / eq, and the number-average molecular weight was 1800. The acrylamide-hydroxyethyl acrylate copolymer was formed by copolymerizing acrylamide and hydroxyethyl acrylate at a mass ratio of 75:25, and had a number-average molecular weight of 9500. The modified acrylic pressure-sensitive adhesive had a solid content of 48.0% and a viscosity of 2100 mPa·s at 25°C.

[0123] The release fabric substrate was woven using the same nylon 66 filament and plain weave method as in Example 1, resulting in an initial air permeability P0 of 350 L / (m²). 2 ·s).

[0124] The data for each coating are shown in Table 4 below: Table 4

[0125] Compared to the second coating, the third coating resulted in an increase of 4.8% in K3, 24.6% in F3, and 14.3% in A3. The P3 / P0 ratio was 0.846. Therefore, the coating process was discontinued after the third coating.

[0126] In this embodiment, the final dry adhesive weight of the adhesive layer is 11.2 g / m³. 2 The adhesive layer thickness is 17μm, the 180° peel strength is 8.6N / 24mm, and the ratio of air permeability after coating to initial air permeability is 0.846.

[0127] Comparative Example 1 This comparative example discloses a method for preparing a single-sided adhesive release fabric. The only difference from Example 1 is that the modified acrylic pressure-sensitive adhesive is formed into an adhesive layer through a one-time coating process.

[0128] Specifically, the modified acrylic pressure-sensitive adhesive from Example 1 was applied in a single coat to one side of the release fabric substrate, with a coating gap of 78 μm and a wet coating weight of 22.5 g / m². 2 After coating, the film is dried sequentially at 75℃ for 1.2 min, at 100℃ for 2.5 min, and then stabilized at 112℃ for 5 min before being laminated with a release paper protective layer.

[0129] In this comparative example, the dry adhesive weight of the adhesive layer is 12.0 g / m². 2 The adhesive layer thickness is 19μm, the 180° peel strength is 10.4N / 24mm, and the air permeability after application is 250L / (m²). 2 ·s), P / P0 is 0.694.

[0130] Comparative Example 2 This comparative example discloses a method for preparing a single-sided adhesive release fabric. The only difference from Example 1 is that a fourth coating is performed after the third coating has satisfied the termination comparison condition.

[0131] The first to third coating processes were the same as in Example 1. For the fourth coating, the coating gap was 32 μm, and the single wet coating weight was 5.6 g / m². 2 After the fourth coating, the film was dried at 75℃ for 1.2 min, at 100℃ for 2.5 min, and then dried at 112℃ for 5 min to stabilize the film.

[0132] The test results after the fourth coating were: the cumulative dry adhesive content A4 was 15.6 g / m². 2 The 180° peel strength (F4) is 12.6 N / 24 mm, and the air permeability (P4) is 231 L / (m²). 2 ·s), P4 / P0 is 0.642, K4 is 0.519.

[0133] In this comparative example, the final dry adhesive layer weight was 15.6 g / m². 2 The adhesive layer thickness is 27μm, the 180° peel force is 12.6N / 24mm, and the ratio of air permeability after coating to initial air permeability is 0.642.

[0134] Comparative Example 3 This comparative example discloses a method for preparing a single-sided adhesive release fabric. The only difference from Example 1 is that coating is only performed once and then stopped after drying.

[0135] Specifically, the first coating process is the same as in Example 1. After the first coating, the film is dried at 112°C for 5 minutes and then the release paper protective layer is attached.

[0136] In this comparative example, the final dry adhesive weight of the adhesive layer was 5.5 g / m². 2 The adhesive layer thickness is 9μm, the 180° peel strength is 4.2N / 24mm, and the air permeability after application is 342L / (m²). 2 ·s), P / P0 is 0.950.

[0137] This comparative example does not establish a coating state corresponding to the termination comparison relationship.

[0138] Comparative Example 4 This comparative example discloses a method for preparing a single-sided adhesive release fabric. The only difference from Example 1 is that the release fabric substrate is a looser plain weave fabric.

[0139] Specifically, the nylon 66 filament specifications are the same as in Example 1; the warp density is 11 yarns / cm and the weft density is 10 yarns / cm during weaving; the warp tension is 22N and the weft tension is 15N; the washing and heat-setting processes are the same as in Example 1. The resulting release fabric substrate has a unit area mass of 42g / m². 2 The thickness is 104 μm, and the initial air permeability P0 is 780 L / (m²). 2 ·s).

[0140] The modified acrylic pressure-sensitive adhesive composition and the three-coat process were the same as in Example 1. After the third coat, the final dry adhesive weight was 11.6 g / m³. 2 The adhesive layer thickness is 18μm, the 180° peel strength is 7.6N / 24mm, and the air permeability after adhesive application is 600L / (m²). 2 ·s), P / P0 is 0.769.

[0141] Comparative Example 5 This comparative example discloses a method for preparing a single-sided adhesive release fabric. The only difference from Example 1 is that a film stabilization and drying stage is not performed after the third coating.

[0142] Specifically, the first to third coatings, the first drying stage and the second drying stage are the same as in Example 1; after the third coating, the film stabilization drying treatment at 112°C for 5 minutes is not performed, and the release paper protective layer is directly bonded.

[0143] In this comparative example, the final dry adhesive weight of the adhesive layer was 10.8 g / m². 2 The adhesive layer thickness is 18μm, the 180° peel strength is 7.9N / 24mm, and the air permeability after adhesive application is 306L / (m²). 2 ·s), P / P0 is 0.850.

[0144] Comparative Example 6 This comparative example discloses a method for preparing a single-sided adhesive release liner. The only difference from Example 1 is that no epoxy-modified acrylate oligomers were added to the modified acrylic pressure-sensitive adhesive.

[0145] Specifically, the modified acrylic pressure-sensitive adhesive, based on 100 parts by total dry adhesive mass, comprises the following components: 96 parts of acrylate copolymer; Four parts of acrylamide-hydroxyethyl acrylate copolymer.

[0146] The specific compositions of the acrylate copolymer and the acrylamide-hydroxyethyl acrylate copolymer are the same as in Example 1. The modified acrylic pressure-sensitive adhesive has a solid content of 48.0% and a viscosity of 1650 mPa·s at 25°C.

[0147] The release fabric substrate, number of coatings, drying conditions, and release paper lamination process were all the same as in Example 1. After the third coating, the final dry adhesive weight of the adhesive layer was 10.8 g / m². 2 The adhesive layer thickness is 18μm, the 180° peel strength is 7.4N / 24mm, and the air permeability after adhesive application is 304L / (m²). 2 ·s), P / P0 is 0.844.

[0148] Performance testing To evaluate the performance of the single-sided adhesive release fabrics obtained in the examples and comparative examples under actual use conditions, their vertical slippage, stability after high-temperature vacuum treatment, and residual adhesive content after peeling were tested.

[0149] 1. Vertical slip detection The epoxy mold gelcoat plate was vertically fixed. A 300mm × 300mm single-sided adhesive release fabric sample was cut, the release paper protective layer was removed, and the sample was adhered to the surface of the gelcoat plate. It was then rolled twice with a 2kg roller and placed vertically at 60℃ for 30 minutes. The maximum displacement of the lower edge of the sample relative to its initial position was measured as the vertical slippage. This test was used to evaluate the positioning ability of the release fabric in curved, inclined, and vertical laying conditions.

[0150] The test results are shown in Table 5.

[0151] Table 5. Test results of vertical tiling positioning performance.

[0152] 2. Stability testing after high-temperature vacuum treatment After removing the release paper protective layer, each sample was adhered to the surface of the epoxy mold gel coat plate and rolled twice with a 2kg roller. It was then placed in a vacuum bag and maintained at a vacuum of -0.092MPa and 130℃ for 4 hours. After treatment, the samples were cooled to 23℃, and the 180° peel force and air permeability were measured. The rate of change in peel force and air permeability were calculated. The rate of change in peel force was calculated as the ratio of the difference in 180° peel force before and after treatment to the 180° peel force before treatment; the rate of change in air permeability was calculated as the ratio of the difference in air permeability before and after treatment to the air permeability before treatment.

[0153] The test results are shown in Table 6 and Figure 1 and Figure 2 As shown.

[0154] Table 6. Stability test results after high-temperature vacuum treatment

[0155] 3. Detection of residual adhesive after peeling The sample, after high-temperature vacuum treatment, was peeled off from the surface of the epoxy mold gel coat plate, and a 100cm section was selected. 2 The test area was wiped 20 times with a pre-weighed, dust-free wiping cloth soaked in ethyl acetate. The cloth was then dried at 60°C for 30 minutes, cooled to room temperature, and weighed. The difference in mass before and after wiping was taken as the residual adhesive content, expressed in mg / 100cm³. 2 At the same time, observe whether there are visible glue marks, fiber fraying, or localized contamination on the surface of the epoxy mold gel coat.

[0156] The test results are shown in Table 7 below.

[0157] Table 7 Results of residual adhesive and surface condition after peeling

[0158] The test results above show that the single-sided adhesive release fabrics obtained in Examples 1-5 exhibit good overall performance in terms of vertical laying and positioning, stability after high-temperature vacuum treatment, and control of residual adhesive after peeling. The small vertical slippage in each example indicates that the adhesive layer can form a moderate temporary positioning effect on the mold surface, which is beneficial for the release fabric to maintain a relatively stable adhesion when laid on curved, inclined, and vertical areas.

[0159] After high-temperature vacuum treatment, the rate of change of 180° peel force and the rate of change of air permeability in each embodiment remained at a low level, indicating that the adhesive layer has a relatively stable interface state and porosity retention state under simulated wind turbine blade molding and curing conditions. This result shows that the adhesive layer obtained by controlling the application, drying, and termination comparison relationships can still maintain good positioning stability under heating and vacuum environments.

[0160] The results of residual adhesive testing after peeling showed that the residual adhesive amount in all embodiments was at a low level, and the surface of the epoxy mold gel coat remained clean overall. This result indicates that after the adhesive layer completes its laying and positioning function, it can be effectively peeled off along with the release cloth, reducing the risk of adhesive residue and localized contamination on the surface of the part.

[0161] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a single-sided adhesive release fabric for wind turbine blade molding, characterized in that, Includes the following steps: S1: Nylon 66 filament, nylon 6 filament or polyester filament are woven into a plain weave fabric, and the plain weave fabric is cleaned and heat-set to obtain a release fabric substrate. S2: Measure the initial air permeability P0 of the release fabric substrate before coating; S3: Apply the modified acrylic pressure-sensitive adhesive to one side of the release cloth substrate and perform the first drying to complete the first coating; S4: Repeat the application and drying of modified acrylic pressure-sensitive adhesive on the same coating side of the release cloth substrate, so that the modified acrylic pressure-sensitive adhesive forms an adhesive layer layer by layer on one side of the release cloth substrate, and the total number of coatings is 2 to 5. S5: After each coating and drying, the cumulative dry adhesive amount A after that coating is determined using test samples prepared simultaneously in the same batch. i 180° peel force F i and breathability P i And calculate the coating balance coefficient K after the i-th coating. i ; ； Where i is an integer from 2 to 5; Fᵢ is the 180° peel force measured after the i-th coating and drying, in N / 24mm; Pᵢ is the air permeability after the i-th coating and drying, in L / (m²). 2 •s); P0 is the initial air permeability of the release fabric substrate before coating, in L / (m²). 2 ·s); Aᵢ represents the cumulative dry adhesive amount after the i-th coating and drying, in g / m³. 2 ; The coating result after the i-th coating and the coating result after the (i-1)-th coating satisfy the following relationship: ； ； ； ； S6: A release paper protective layer is attached to the outside of the adhesive layer, and after slitting and winding, a single-sided adhesive release cloth for wind turbine blade forming is obtained. The final dry adhesive weight A of the adhesive layer is 8-24 g / m³. 2 The thickness is 8-38μm, and the 180° peel force of the single-sided adhesive release cloth is 4.8-12N / 24mm.

2. The method for preparing the single-sided adhesive release fabric for wind turbine blade molding according to claim 1, characterized in that, The release fabric substrate has a warp density of 14-25 threads / cm, a weft density of 14-25 threads / cm, and a unit area mass of 80-110 g / m². 2 The thickness is 130–210 μm, and the initial air permeability P0 is 120–650 L / (m²). 2 The initial air permeability P0 was measured at a pressure difference of 100 Pa (s).

3. The method for preparing the single-sided adhesive release fabric for wind turbine blade molding according to claim 1, characterized in that, In step S1, during weaving, the warp tension is controlled at 18–35 N and the weft tension at 10–26 N. During cleaning, the plain weave fabric is treated in a water bath at 40–60 °C for 2–8 minutes, and the moisture is removed under the condition of a liquid-pinching rate of 45%–75%. The heat-setting temperature is 150–190 °C, the heat-setting time is 30–90 s, and during the heat-setting process, the longitudinal overfeed rate is controlled at 0%–3% and the transverse stretching rate is controlled at 0%–4%.

4. The method for preparing the single-sided adhesive release fabric for wind turbine blade molding according to claim 1, characterized in that, The modified acrylic pressure-sensitive adhesive in step S3 has a coating viscosity of 800–3500 mPa·s, a solid content of 38%–58%, and a coating gap of 15–80 μm. After the modified acrylic pressure-sensitive adhesive is coated on one side of the release fabric substrate, it is pressed to form a single-coated adhesive layer. The pressing pressure is 0.10–0.45 MPa, the temperature is 35–70 °C, and the speed is 3–18 m / min.

5. The method for preparing the single-sided adhesive release fabric for wind turbine blade molding according to claim 1, characterized in that, In step S4, the cumulative dry adhesive amount A1 after the first coating is 35% to 60% of the final dry adhesive amount A; the additional dry adhesive amount of the i-th coating relative to the (i-1)-th coating is 1.0 to 6.0 g / m³. 2 The interval between two consecutive coatings is 2 to 20 minutes.

6. The method for preparing the single-sided adhesive release fabric for wind turbine blade molding according to claim 1, characterized in that, The drying process after each coating includes a first drying stage and a second drying stage. The temperature of the first drying stage is 65-85℃ and the time is 0.5-2.0 min. The temperature of the second drying stage is 85-115℃ and the time is 1.0-4.0 min. The drying process after the last coating also includes a film stabilization drying stage, where the temperature is 100-125℃ and the time is 2-8 min.

7. The method for preparing the single-sided adhesive release fabric for wind turbine blade molding according to claim 1, characterized in that, The modified acrylic pressure-sensitive adhesive comprises an acrylate copolymer, a heat-resistant cohesive reinforcing component, and a polar anchoring component; Based on the total dry mass of the modified acrylic pressure-sensitive adhesive, the acrylate copolymer accounts for 82% to 96%, the heat-resistant cohesive reinforcing component accounts for 2% to 10%, and the polar anchoring component accounts for 1% to 8%. The glass transition temperature of the acrylate copolymer is -35℃ to -10℃, and the gel content of the adhesive layer formed by the modified acrylic pressure-sensitive adhesive is 45% to 78%.

8. The method for preparing the single-sided adhesive release fabric for wind turbine blade molding according to claim 1, characterized in that, There exists at least one instance where the coating result after the j-th coating and the coating result after the (j-1)-th coating satisfy the following relationship: ； ； ； Where j is an integer from 2 to 4, and j < i.

9. A single-sided adhesive release fabric for wind turbine blade molding, characterized in that, The single-sided adhesive release fabric is prepared by the preparation method according to any one of claims 1 to 8; The single-sided adhesive release cloth includes a release cloth substrate, an adhesive layer disposed on one side of the release cloth substrate, and a release paper protective layer adhered to the outside of the adhesive layer. The adhesive layer is a modified acrylic pressure-sensitive adhesive layer, and the final dry weight of the adhesive layer is 8-24 g / m³. 2 The thickness is 8–38 μm; The 180° peel force of the single-sided adhesive release cloth is 4.8 to 12 N / 24 mm, and the ratio of the air permeability after coating to the initial air permeability of the release cloth substrate before coating is 0.72 to 0.

95.

10. The single-sided adhesive release fabric for wind turbine blade molding according to claim 9, characterized in that, After the single-sided adhesive release cloth is peeled off from the cured epoxy resin board, the amount of residual adhesive on the surface of the cured epoxy resin board is no more than 0.8 mg / 100 cm². 2 .

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