High-efficiency halogen-free flame-retardant adhesive tape and preparation method thereof

Abstract

This invention discloses a high-efficiency halogen-free flame-retardant tape and its preparation method. The flame-retardant tape has a layered structure composed of layers from top to bottom, with each layer consisting of a flame-retardant acrylic adhesive layer and a release paper layer from top to bottom. The flame-retardant acrylic adhesive layer is a dense, non-porous film layer, in which phosphorus-based and nitrogen-based halogen-free flame-retardant components are uniformly distributed in the acrylic adhesive matrix. The flame-retardant acrylic adhesive layer completely covers the surface of the release paper layer, forming a tightly bonded integrated structure. This ensures that the flame-retardant acrylic adhesive layer forms a dense, continuous, and non-porous structure, and that the phosphorus-based and nitrogen-based halogen-free flame-retardant components are uniformly distributed in the adhesive matrix, significantly improving the overall structural stability and flame-retardant performance of the tape. This invention focuses on innovation in process flow and calculation steps, without requiring complex mechanical adjustments, resulting in strong process controllability, excellent batch-to-batch performance consistency, and suitable raw material costs for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of flame retardant tape technology, specifically a high-efficiency halogen-free flame retardant tape and its preparation method. Background Technology

[0002] Flame-retardant tapes are widely used in fixed locations where flame retardancy is required, such as power batteries, home appliances, automobiles, train carriages, and aircraft interior decoration materials. Their flame-retardant performance, structural stability, and environmental friendliness directly determine the product's safety and applicability.

[0003] In the existing manufacturing process of flame-retardant tapes, traditional products mostly use bromine-based halogenated flame retardants as the core flame-retardant component. Although they have the advantages of low raw material cost and good flame-retardant performance, they release a large amount of toxic fumes and produce highly corrosive gases during combustion. This not only easily causes environmental pollution and equipment corrosion, but also poses serious safety hazards. Currently, the European Union, China and many other countries have issued regulations that clearly restrict the addition and use of halogenated flame retardants such as polybrominated diphenyl ethers.

[0004] To meet the market and regulatory requirements for environmentally friendly flame retardants, halogen-free flame retardant tapes using phosphorus-based and nitrogen-based components have emerged in the existing technology. However, the preparation process of such products still has many core defects: there is no unified calculation basis for the ratio of phosphorus-based and nitrogen-based flame retardant components, which is mostly determined by experience. The scientific ratio logic is not designed in combination with the core material characteristics of acrylic adhesives, which easily leads to problems such as uneven dispersion of flame retardant components and high porosity of adhesive layer.

[0005] The flame-retardant acrylic adhesive layer has poor structural stability and poor char layer formation, which in turn affects the flame-retardant performance of the product. The density and flame-retardant performance of the adhesive layer vary greatly among different batches of products, which cannot meet the actual needs of large-scale production. Summary of the Invention

[0006] In view of the shortcomings of the existing technology mentioned above.

[0007] This invention provides a high-efficiency halogen-free flame-retardant tape, which has a layered structure that is laminated from top to bottom, with each layer consisting of a flame-retardant acrylic adhesive layer and a release paper layer from top to bottom.

[0008] The flame-retardant acrylic adhesive layer is a non-porous and dense film layer, and the phosphorus-based halogen-free flame-retardant components and nitrogen-based halogen-free flame-retardant components are uniformly distributed in the acrylic adhesive matrix.

[0009] The flame-retardant acrylic adhesive layer completely covers the surface of the release paper layer and forms a tightly bonded integral structure with the release paper layer;

[0010] The flame-retardant acrylic adhesive layer is prepared by mixing and dispersing acrylic adhesive, phosphorus-based halogen-free flame-retardant components and nitrogen-based halogen-free flame-retardant components according to the measured solid content of acrylic adhesive, allowing them to stand and mature, and then coating and gradient baking to form a film.

[0011] The release paper layer is the molding base for the flame-retardant acrylic adhesive layer.

[0012] This invention also proposes a method for preparing a high-efficiency halogen-free flame-retardant tape, comprising the following steps:

[0013] S1. Detect the solid content of the acrylic adhesive using a solid content analyzer, calculate the addition ratio of the phosphorus-based halogen-free flame retardant component and the nitrogen-based halogen-free flame retardant component based on the solid content value, and weigh the acrylic adhesive, phosphorus-based halogen-free flame retardant component and the nitrogen-based halogen-free flame retardant component according to the calculated ratio.

[0014] S2. The acrylic adhesive is heated and then mixed and dispersed in multiple stages according to the order of material addition. After dispersion, the mixed and dispersed system is allowed to stand and mature to obtain flame-retardant acrylic adhesive.

[0015] S3. Apply flame-retardant acrylic adhesive to the surface of the release paper layer to form a flame-retardant acrylic adhesive wet film; detect the surface viscosity and surface tension of the flame-retardant acrylic adhesive wet film, calculate the ratio of the two test values, and determine the process parameters for gradient baking to form the film based on the calculation results.

[0016] S4. The film-forming temperature range of the acrylic adhesive is detected by differential scanning calorimetry. The temperature and time parameters for gradient baking are calculated based on the film-forming temperature range. The substrate with the adhesive wet film is subjected to gradient baking according to the calculated parameters, so that the flame-retardant acrylic adhesive wet film is formed into a flame-retardant acrylic adhesive layer.

[0017] S5. Surface protection treatment is applied to the molded flame-retardant acrylic adhesive layer to obtain a high-efficiency halogen-free flame-retardant tape.

[0018] The technical solutions provided by the embodiments of this disclosure have at least the following beneficial effects:

[0019] This invention solves the problems of high smoke and toxicity, strong corrosiveness, and environmental pollution associated with traditional halogenated flame-retardant tapes. It also overcomes the shortcomings of existing halogen-free flame-retardant tapes, such as uneven dispersion of flame-retardant components, porous adhesive layers, poor char layer formation, poor product quality stability, and low reproducibility. It ensures a dense, continuous, and non-porous structure in the flame-retardant acrylic adhesive layer, with phosphorus- and nitrogen-based halogen-free flame-retardant components evenly distributed in the adhesive matrix. This significantly improves the overall structural stability and flame-retardant performance of the tape. The invention focuses entirely on innovative process flow and calculation steps, requiring no complex mechanical adjustments. It offers strong process controllability, excellent batch-to-batch performance consistency, and cost-effective raw materials, making it suitable for large-scale production. Attached Figure Description

[0020] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0022] Please see Figure 1 This application provides a high-efficiency halogen-free flame retardant tape, which has a layered structure that is composited from top to bottom. The layers are, from top to bottom, a flame retardant acrylic adhesive layer and a release paper layer.

[0023] The flame-retardant acrylic adhesive layer is a non-porous and dense film layer, and the phosphorus-based halogen-free flame-retardant components and nitrogen-based halogen-free flame-retardant components are uniformly distributed in the acrylic adhesive matrix.

[0024] The flame-retardant acrylic adhesive layer completely covers the surface of the release paper layer and forms a tightly bonded integral structure with the release paper layer;

[0025] The flame-retardant acrylic adhesive layer is prepared by mixing and dispersing acrylic adhesive, phosphorus-based halogen-free flame-retardant components and nitrogen-based halogen-free flame-retardant components according to the measured solid content of acrylic adhesive, allowing them to stand and mature, and then coating and gradient baking to form a film.

[0026] The release paper layer is the molding base for the flame-retardant acrylic adhesive layer.

[0027] As an optional embodiment, the addition ratio of phosphorus-based halogen-free flame retardant components is determined based on the measured solid content of acrylic adhesive, and the addition ratio of nitrogen-based halogen-free flame retardant components is determined based on the determined addition ratio of phosphorus-based halogen-free flame retardant components.

[0028] The temperature and time parameters used in gradient baking to form the film are determined based on the measured film-forming characteristics of the acrylic adhesive. The calculation process is based on the film-forming characteristics of the acrylic adhesive and the physical properties of the phosphorus-based and nitrogen-based halogen-free flame-retardant components. The calculation results directly correspond to the microstructure of the flame-retardant acrylic adhesive layer.

[0029] As an optional embodiment, the molding process parameters of the flame-retardant acrylic adhesive layer are calculated using the measured surface viscosity and measured surface tension values ​​of the flame-retardant acrylic adhesive wet film as the calculation objects. The ratio of the two parameters is used to determine the parameters. The ratio calculation result directly corresponds to the physical state of the flame-retardant acrylic adhesive wet film, and the physical state of the flame-retardant acrylic adhesive wet film is compatible with the process conditions of gradient baking for film formation.

[0030] As an optional embodiment, the flame-retardant structure of the high-efficiency halogen-free flame-retardant tape is composed solely of the dense and continuous structure of the flame-retardant acrylic adhesive layer. The dense and continuous structure of the flame-retardant acrylic adhesive layer is formed by a combination of mixing and dispersion, static curing, coating, and gradient baking film-forming process. The microstructure of the flame-retardant acrylic adhesive layer is controlled by the ratio of phosphorus-based and nitrogen-based halogen-free flame-retardant components and their dispersion state in the acrylic adhesive matrix. The dispersion state of the two components is determined by the calculation results of the mixing and dispersion process parameters.

[0031] As an optional embodiment, the following steps are included:

[0032] S1. Detect the solid content of the acrylic adhesive using a solid content analyzer, calculate the addition ratio of the phosphorus-based halogen-free flame retardant component and the nitrogen-based halogen-free flame retardant component based on the solid content value, and weigh the acrylic adhesive, phosphorus-based halogen-free flame retardant component and the nitrogen-based halogen-free flame retardant component according to the calculated ratio.

[0033] S2. The acrylic adhesive is heated and then mixed and dispersed in multiple stages according to the order of material addition. After dispersion, the mixed and dispersed system is allowed to stand and mature to obtain flame-retardant acrylic adhesive.

[0034] S3. Apply flame-retardant acrylic adhesive to the surface of the release paper layer to form a flame-retardant acrylic adhesive wet film; detect the surface viscosity and surface tension of the flame-retardant acrylic adhesive wet film, calculate the ratio of the two test values, and determine the process parameters for gradient baking to form the film based on the calculation results.

[0035] S4. The film-forming temperature range of the acrylic adhesive is detected by differential scanning calorimetry. The temperature and time parameters for gradient baking are calculated based on the film-forming temperature range. The substrate with the adhesive wet film is subjected to gradient baking according to the calculated parameters, so that the flame-retardant acrylic adhesive wet film is formed into a flame-retardant acrylic adhesive layer.

[0036] S5. Surface protection treatment is applied to the molded flame-retardant acrylic adhesive layer to obtain a high-efficiency halogen-free flame-retardant tape.

[0037] As an optional embodiment, in step S1, the coefficients used to calculate and determine the addition ratio of phosphorus-based halogen-free flame retardant components and nitrogen-based halogen-free flame retardant components are all determined by actual measurements through film-forming experiments and dispersion experiments of the corresponding materials.

[0038] Film formation experiments were conducted by coating acrylic adhesives with different solid contents into films, observing the pore state of the film layers, and determining the relevant parameters for non-pore film formation.

[0039] The dispersion experiment involved dispersing different ratios of acrylic adhesive, phosphorus-based halogen-free flame retardant components, and nitrogen-based halogen-free flame retardant components separately, detecting the dispersion uniformity of the flame retardant components, and determining the relevant parameters for dispersion adaptation.

[0040] As an optional embodiment, in step S2, the mixing and dispersion is carried out in stages according to the order of material addition. The process parameters for dispersion in each stage are determined by calculation based on the flowability of the acrylic adhesive and the dispersion characteristics of the phosphorus-based halogen-free flame retardant component and the nitrogen-based halogen-free flame retardant component. The parameters are gradually adjusted according to the dispersion stage. The dispersion process is carried out at a uniform speed to ensure that all materials are fully mixed and there is no agglomeration. The heating parameters are determined by calculation based on the flowability characteristics of the acrylic adhesive, and the standing curing time parameters are determined by calculation based on the stability characteristics of the mixed dispersion system.

[0041] As an optional embodiment, in step S3, the coating thickness of the flame-retardant acrylic adhesive wet film is determined by calculation based on the surface characteristics of the release paper layer and the film-forming characteristics of the flame-retardant acrylic adhesive layer; the coating process is kept at a uniform speed to ensure uniform wet film thickness; the static environment parameters of the flame-retardant acrylic adhesive wet film are determined by calculation based on the stability characteristics of the surface viscosity and surface tension of the wet film.

[0042] As an optional embodiment, in step S4, the multiple stages of gradient baking to form a film are implemented sequentially according to the film-forming reaction process of the acrylic adhesive. The stage division is determined by calculation based on the film-forming temperature range of the acrylic adhesive. The temperature and time parameters of each baking stage are determined by calculation based on the range of the film-forming temperature range and the thickness of the wet film of the adhesive. The gradient cooling rate parameter is determined by calculation based on the thermal stability characteristics of the flame-retardant acrylic adhesive layer after film formation.

[0043] As an optional embodiment, in step S5, the process parameters of the surface protection treatment are determined based on the surface characteristics of the flame-retardant acrylic adhesive layer and the adaptability to the usage environment; the temperature and time parameters of the protection treatment are determined based on the surface tension of the adhesive layer and the reaction characteristics of the protective agent; the environmental parameters are kept constant during the treatment process, and the surface state of the adhesive layer after treatment directly corresponds to the calculation results.

[0044] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0045] Example 1

[0046] This embodiment provides a method for preparing high-efficiency halogen-free flame-retardant tape. The specific steps are as follows: S1, Raw material ratio calculation and weighing: The solid content of the acrylic adhesive is detected using a solid content analyzer (detection accuracy ±0.1%). The solid content is measured in parallel three times, and the average value is taken as the final measured solid content value X (unit: mass percentage). The addition ratio Vphosphorus of the phosphorus-based halogen-free flame-retardant component is calculated according to the calculation formula Vphosphorus=X×(1-η) (unit: mass percentage, based on the total mass of the acrylic adhesive). The addition ratio Vnitrogen of the nitrogen-based halogen-free flame-retardant component is calculated according to the calculation formula Vnitrogen=Vphosphorus×λ (unit: mass percentage, based on the total mass of the acrylic adhesive). η was determined through film formation experiments: Five groups of acrylic adhesives with different solid contents (X-2%, X-1%, X, X+1%, X+2%) were selected and coated under the same coating conditions (coating speed 5m / min). The film thickness was controlled at 20μm. After standing for 24h in an environment of 25℃ and 50% relative humidity, the pore state of each film layer was observed using an electron microscope (magnification 5000x). The minimum solid content of the non-porous film was counted (denoted as Xmin). Substituting this into η=Xmin / X, the value of η (range 0.6-0.8) was calculated. λ was determined through dispersion experiments: Five groups of phosphorus-based and nitrogen-based halogen-free flame retardant components with different ratios (Vphosphorus / Vnitrogen were selected, with ratios of 1:1, 1:2, 2:1, 2:3, and 3:2 respectively), and mixed with acrylic adhesive. The mixtures were dispersed under the same dispersion parameters (3000 r / min rotation speed, 30 min time). The particle size distribution (D90) of the flame retardant components was measured using a laser particle size analyzer, and the dispersion uniformity was observed using an electron microscope. The optimal ratio with D90 ≤ 5 μm and no obvious agglomeration was selected as the λ value (range 1.2-2.5). Based on the calculated Vphosphorus and Vnitrogen ratios, 100 kg of acrylic adhesive, 100 kg of phosphorus-based halogen-free flame retardant component (ammonium polyphosphate, degree of polymerization n ≥ 1000) Vphosphorus × 100 kg, and 100 kg of nitrogen-based halogen-free flame retardant component (melamine cyanurate) Vnitrogen × 100 kg were weighed.

[0047] S2. Mixing, Dispersion and Curing: Symmetrically taken acrylic adhesives are subjected to heating treatment. The heating parameters are determined based on the flow characteristics of the acrylic adhesives. The viscosity of the acrylic adhesives at different temperatures (25℃, 30℃, 35℃, 40℃, 45℃) is measured by a rotational viscometer. The temperature corresponding to a viscosity of 5000-8000 mPa·s is selected as the target heating temperature (denoted as T_lift, usually 35-40℃). The heating rate is controlled at 2℃ / min until the system temperature stabilizes at T_lift ± 1℃. Add the phosphorus-based halogen-free flame retardant component first according to the material addition order, and implement the first stage of dispersion: the dispersion speed is determined based on the fluidity of the acrylic adhesive (viscosity value at T liters), and the calculation logic is speed = k1 × (10000 / viscosity), where k1 is the dispersion coefficient (determined to be 0.8-1.0 through dispersion experiments). The dispersion speed in the first stage is controlled at 1500-2000 r / min. The dispersion time is determined based on the dispersion characteristics of the phosphorus-based flame retardant component. The calculation formula is: time = k2 × (particle size / 10), where k2 is the time coefficient, with a value of 1.5-2.0). The dispersion time in the first stage is 20-30 min. After the first stage of dispersion, a nitrogen-based halogen-free flame retardant component is added, and the second stage of dispersion is carried out. The dispersion speed is determined based on the dispersion characteristics (particle hardness, specific surface area) of the nitrogen-based flame retardant component. The calculation logic is: speed = first stage speed × k3, where k3 is the adaptation coefficient (determined to be 1.1-1.3 through dispersion experiments). The dispersion speed in the second stage is controlled at 1800-2500 r / min, and the dispersion time is consistent with that in the first stage. After dispersion, the mixed dispersion system is subjected to static curing treatment. The curing time parameter is determined based on the stability characteristics of the mixed dispersion system. By detecting the viscosity change rate of the dispersed system at different static times (0h, 2h, 4h, 6h, 8h), the shortest time with a viscosity change rate ≤3% is selected as the curing time (usually 4-6h). During the curing process, the system is kept in a undisturbed environment at TL ± 1℃ to obtain the flame-retardant acrylic adhesive.

[0048] S3. Wet film preparation and baking parameter determination: The flame-retardant acrylic adhesive is coated onto the surface of the release paper layer (silicone paper with a surface tension of 30-35 mN / m). The coating thickness is calculated and determined based on the surface characteristics of the release paper layer and the film-forming characteristics of the flame-retardant acrylic adhesive layer. The calculation formula is: thickness = k4 × (X / 50), where k4 is the thickness coefficient (determined to be 30-50 μm based on film-forming experiments). The coating thickness is controlled at 30-50 μm. The coating process is kept at a uniform speed = coating thickness × k5, where k5 is the speed coefficient, with a value of 0.1-0.2 m / (min·μm). This ensures that the wet film thickness is uniform (thickness deviation ≤ ±1 μm). After the flame-retardant acrylic adhesive wet film is formed, it is placed under constant environmental conditions. The environmental parameters are calculated and determined based on the stability characteristics of the surface viscosity and surface tension of the wet film: temperature is controlled at 25±1℃, humidity is controlled at 50±3%, wind speed is ≤0.1m / s, and the standing time is 10-15min to ensure the stability of the wet film. A rotational viscometer (accuracy ±10 mPa·s) and a surface tension meter (accuracy ±0.1 mN / m) were used to measure the surface viscosity μ (unit: mPa·s) and surface tension σ (unit: mN / m) of the wet film, respectively. Five points were selected, including the center and four corners of the wet film, and the average value was taken as the measured value. The ratio of the two measured values ​​was calculated as R=μ / σ (unit: (mPa·s) / (mN / m)). Based on the calculation results, the basic process parameters for gradient drying to form the film were determined as follows: when R=50-80, the drying start temperature is 60℃; when R=80-120, the drying start temperature is 70℃; when R=120-150, the drying start temperature is 80℃.

[0049] S4. Gradient Baking for Film Formation: The film-forming temperature range [T0, T1] of the acrylic adhesive was determined using differential scanning calorimetry (DSC). The testing conditions were a nitrogen atmosphere (flow rate 50 mL / min), a heating rate of 10℃ / min, and a temperature range of 25-200℃. The temperature range above the adhesive's glass transition temperature without significant enthalpy change was recorded as the film-forming temperature range [T0, T1] (typically T0 = 60-70℃, T1 = 120-140℃). Based on this film-forming temperature range and the thickness of the wet film, the stages of gradient baking for film formation were calculated and determined: the temperature ranges [T0, (T0+T1) / 2] and [(T0+T1) / 2, T1] were divided into two baking stages. The stage division ratio was positively correlated with the wet film thickness (the thicker the film, the higher the proportion of the first stage). The temperature and time parameters for each stage are calculated and determined as follows: First stage temperature = T0 + 10℃, time = thickness × k6 (k6 is the time coefficient, with a value of 1.5-2.0 min / μm); Second stage temperature = T1 - 10℃, time = first stage time × (0.8-1.0; Wind speed parameters are calculated and determined based on the density requirements of the flame-retardant acrylic adhesive layer. Calculation formula: Wind speed = k7 × (stage temperature / 100), k7 is the wind speed coefficient, with a value of 0.3-0.5 m / s). According to the calculated parameters, the substrate with the adhesive wet film is subjected to gradient baking to form a film: the first stage is baked at 60-80℃ and wind speed of 0.3-0.4m / s for 30-60min, and the second stage is baked at 110-130℃ and wind speed of 0.4-0.5m / s for 20-40min; after the film is formed, it is cooled to room temperature at a rate determined by calculation based on the thermal stability characteristics of the flame retardant acrylic adhesive layer: cooling rate = k8×(T1 / 100), where k8 is the cooling coefficient (value is 0.5-1.0℃ / min). During the cooling process, the humidity of the baking environment is kept ≤30% to form the flame retardant acrylic adhesive wet film into a flame retardant acrylic adhesive layer.

[0050] S5. Surface Protection Treatment: A water-based protective agent (fluorinated acrylate emulsion, solid content 30-40%) is selected as the protective agent. The process parameters for surface protection treatment are determined based on the surface characteristics of the flame-retardant acrylic adhesive layer and its compatibility with the application environment: Protective agent coating amount = k9 × (adhesive layer surface tension / 30), where k9 is the coating amount coefficient (value 5-10 g / m³). 2 The coating amount should be controlled at 5-10 g / m². 2 Temperature and time parameters are calculated and determined based on the surface tension of the adhesive layer and the reaction characteristics of the protective agent: Temperature = Surface tension of adhesive layer × k10 (k10 = 2-3℃ / (mN / m)), controlled at 60-90℃; Time = Coating amount × k11 (k11 = 1-2min / (g / m)). 2The processing time is controlled at 5-15 minutes; the ambient temperature is kept constant and undisturbed during the process, and the surface state of the adhesive layer after processing directly corresponds to the calculation results (surface tension 25-30mN / m, water contact angle ≥90°), ensuring the flame retardant stability and durability of the adhesive layer, and producing a high-efficiency halogen-free flame retardant tape.

[0051] Example 2

[0052] This embodiment provides a method for preparing high-efficiency halogen-free flame-retardant tape. The steps are basically the same as in Example 1, except that in step S1, the film-forming experiment of η and the dispersion experiment of λ are carried out in multiple parallel experiments. For the film-forming experiment, 10 groups of acrylic adhesives with different solid contents (X-4% to X+5%, with an interval of 1%) were selected. For the dispersion experiment, 8 groups of phosphorus-based and nitrogen-based halogen-free flame-retardant components with different ratios (Vphosphorus / Vnitrogen = 1:3 to 3:1, with an interval of 0.5) were selected. Each experiment was performed in parallel three times. The average value of multiple sets of measured data was taken as the final η and λ values. The calculation process strictly followed the derivation logic of parallel experimental data (averaging after removing outliers; the outlier judgment standard was deviation from the average value ±10%), improving the accuracy of the ratio calculation. In step S2, during the calculation of process parameters for mixing and dispersion at each stage, the particle size characteristics of the phosphorus-based and nitrogen-based halogen-free flame retardant components are additionally considered (phosphorus-based particle size D50 = 5-10 μm, nitrogen-based particle size D50 = 3-8 μm), and the calculation results are finely adjusted: the smaller the particle size, the lower the dispersion speed by 5-10% and the longer the dispersion time by 10-15%, ensuring that the flame retardant components are more uniformly dispersed in the acrylic adhesive matrix (D90 ≤ 3 μm), avoiding local agglomeration. In step S4, during the calculation of temperature and time parameters for each stage of gradient baking to form a film, the film-forming shrinkage characteristics of the flame-retardant acrylic adhesive layer (detected by a thermomechanical analyzer TMA, shrinkage rate ≤ 2%) are optimized: the temperature in the first stage is reduced by 5-10℃ and the time is extended by 10%-20%, further improving the density of the flame-retardant acrylic adhesive layer (porosity ≤ 0.1%) and optimizing the microstructure of the adhesive layer.

[0053] In step S5, during the parameter calculation for surface protection treatment, the diffusion characteristics of the protective agent (diffusion coefficient 1×10⁻⁶) are additionally considered. -6 Up to 5×10 -6 cm 2 / s), fine-tune the temperature and time parameters: the smaller the diffusion coefficient, the higher the temperature by 5-10℃ and the longer the time by 15%-20%, to ensure that the protective agent evenly covers the surface of the adhesive layer (coverage uniformity ≥98%).

[0054] Example 3

[0055] This embodiment provides a method for preparing high-efficiency halogen-free flame-retardant tape, the steps of which are basically the same as those in Embodiment 2, the only difference being:

[0056] In step S1, the film-forming experiment of η and the dispersion experiment of λ both adopted multiple parallel experiments. At the same time, the calculation coefficients were adaptively corrected based on the batch differences of acrylic adhesive, phosphorus-based and nitrogen-based halogen-free flame retardant components (selecting raw materials from 3 different production batches): the correction formula is η'=η×(1+ΔX / X), λ'=λ×(1+ΔD / D), where ΔX is the solid content deviation of different batches and ΔD is the particle size deviation of different batches, to ensure the accuracy of the raw material ratio calculation of different batches (ratio deviation ≤±2%) and improve the batch consistency of the product.

[0057] In step S3, after calculating the ratio of surface viscosity to surface tension of the flame-retardant acrylic adhesive wet film, and combining the standing time parameter of the wet film (t=10-15min), the basic process parameters for gradient baking to form the film are verified for the second time: the verification formula is initial temperature'=initial temperature×(1+t / 15), to ensure the compatibility between the baking parameters and the physical state of the wet film (parameter compatibility deviation ≤±3℃).

[0058] In step S4, during the parameter calculation process of gradient baking to form the film, the baking temperature parameters are dynamically fine-tuned in combination with the real-time fluctuations of ambient temperature and humidity (detected in real time by an environmental sensor): for every 1°C increase in ambient temperature, the baking temperature decreases by 2°C; for every 5% increase in ambient humidity, the baking temperature increases by 3°C; during the cooling process, the cooling rate is slightly corrected in combination with the real-time temperature feedback of the adhesive layer (detected by an infrared thermometer) (when the temperature deviation is ≤ ±2°C, the rate remains unchanged; when the deviation is > ±2°C, the rate is adjusted to ±0.2°C / min). In step S5, during the parameter calculation of the surface protection treatment, the treatment time is dynamically adjusted in combination with the influence of environmental humidity fluctuations on the reaction rate of the protective agent (the reaction rate decreases by 15% for every 10% increase in humidity): the adjustment formula is time' = time × (1 + ΔRH / 10), where ΔRH is the humidity deviation; after the treatment is completed, the protection parameters are optimized a second time based on the surface condition test results of the adhesive layer (surface tension, water contact angle): if the surface tension is >30mN / m, 20-30% of the protective agent coating amount is applied again; if the water contact angle is <90°, the treatment time is extended by 10-15%, so as to achieve a synergistic improvement in the density of the adhesive layer, flame retardant stability and surface protection effect.

[0059] Comparative Example 1

[0060] This comparative example provides a method for preparing flame-retardant tape, the steps of which are basically the same as those in Example 1, the difference being: no system parameter calculations based on the actual measured characteristics of the materials are performed throughout the process; in step S1, the addition ratio of phosphorus-based halogen-free flame-retardant component is determined empirically to be 20% and the addition ratio of nitrogen-based halogen-free flame-retardant component is determined to be 10%, and no film-forming experiment or dispersion experiment is performed; in step S2, the temperature is determined empirically to be raised to 40℃, and the mixing and dispersion are performed in a single dispersion (2000 r / min rotation speed, 30 min time), with a standing curing time of 5 h, without adjusting parameters in stages, and the mixing and dispersion are performed directly in one go; in step S3... The coating thickness was determined to be 40 μm based on experience, and the coating speed was 5 m / min. The viscosity and surface tension of the wet film were not measured, and the initial temperature for film drying was determined to be 70℃ based on experience. In step S4, the film was dried at a constant temperature (100℃, 60 min) without gradient drying stages. The cooling process was natural cooling (rate of about 2℃ / min), and the cooling rate was not controlled according to the thermal stability characteristics of the adhesive layer. In step S5, a conventional protective agent was directly applied by simple brushing (coating amount 8 g / m², temperature 80℃, time 10 min). The protective temperature and time were determined based on experience.

[0061] Comparison results

[0062] The high-efficiency halogen-free flame-retardant tapes prepared in Examples 1, 2, 3, and Comparative Example 1 were tested for four core indicators: flame-retardant component dispersibility, adhesive layer integrity, char layer density, and surface protection stability. The testing methods are as follows:

[0063] Flame retardant component dispersibility: The internal microstructure of the flame retardant acrylic adhesive layer was observed using an electron microscope, and the proportion of agglomerated area of ​​the flame retardant components was statistically analyzed and divided into three levels: uniform distribution (agglomerated area < 0.1%), local agglomerated (agglomerated area 0.1%–0.5%), and large-scale agglomerated (agglomerated area ≥ 0.5%).

[0064] Adhesive layer integrity: The surface and internal structure of the adhesive layer were observed using an electron microscope (magnification 2000x). The percentage of pore and crack area was statistically analyzed and divided into three levels: complete and without defects (defect area < 0.1%), slightly defective (defect area 0.1%-0.5%), and severely defective (defect area ≥ 0.5%).

[0065] Charcoal layer density: After the samples were subjected to vertical combustion tests according to GB / T2408-2021 standard, the structural state of the charcoal layer after combustion was observed using an electron microscope (magnification of 1000x). The pore area ratio of the charcoal layer was counted and divided into three levels: dense and non-porous (pore area < 0.1%), slightly loose (pore area 0.1%-0.5%), and severely loose (pore area ≥ 0.5%).

[0066] Surface protection stability: After aging the sample in an environment of 40℃ and 85% relative humidity for 72 hours, the surface tension of the adhesive layer was tested using a surface tension meter, and the water contact angle was tested using a contact angle meter. The results were divided into three levels: no discoloration, no wrinkling (surface tension 25-30mN / m, water contact angle ≥90°), slight discoloration (discoloration area 0.1%-1%, surface tension 30-35mN / m, water contact angle 80°-90°), and severe discoloration / wrinkling (discoloration / wrinkling area ≥1%, surface tension >35mN / m, water contact angle <80°).

[0067] The comparison results are shown in the table below:

[0068] sheet

[0069] Group Process characteristics Flame retardant component dispersibility Adhesive layer integrity Carbon layer density Surface protection stability Example 1 Based on the actual measured values ​​of the materials, the basic process parameters are calculated, following the core process of this invention. Uniform distribution Complete and without defects Dense and non-porous No discoloration, no wrinkling Example 2 Based on Example 1, the calculation coefficients were optimized, and the dispersion, baking, and protection parameters were fine-tuned. Uniform distribution (no local clustering) Complete and defect-free (more uniform film formation) Dense and non-porous (more stable structure) No discoloration, no wrinkling Example 3 Based on Example 2, the batch operation coefficients, secondary verification process parameters, and dynamic fine-tuning parameters were modified. Uniform distribution (excellent batch consistency) Complete and without defects (free from environmental impacts). Dense and non-porous (excellent long-term stability) No discoloration, no wrinkling (long-lasting protective effect) Comparative Example 1 (Prior Art) No system parameters were used for calculation; the entire process was based on experience. Large-scale reunions Critical defects Severely loose Severe discoloration / wrinkling

[0070] As can be seen from the above comparative results, the three embodiments of the present invention sequentially optimize the process parameter calculation logic and details based on the measured characteristics of the materials, resulting in a progressive improvement in technical performance: Embodiment 1 achieves uniform dispersion of flame-retardant components, integrity of the adhesive layer, density of the char layer, and good surface protection through basic parameter calculation; Embodiment 2 further improves the stability of each core performance by optimizing the calculation coefficients and fine-tuning the parameters; Embodiment 3 optimizes the batch consistency and long-term stability of the product through batch coefficient correction, secondary verification, and dynamic fine-tuning, completely avoiding the influence of environmental factors and material batch differences. Compared with the existing empirical process (Comparative Example 1), the present invention fundamentally solves the core process defects of existing halogen-free flame-retardant tapes through full-process parameter calculation and process optimization, significantly improving the overall performance of the product.

[0071] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A high-efficiency halogen-free flame-retardant tape, characterized in that, The flame-retardant tape has a layered structure that is laminated from top to bottom. The layers are, from top to bottom, a flame-retardant acrylic adhesive layer and a release paper layer. The flame-retardant acrylic adhesive layer is a non-porous and dense film layer, and the phosphorus-based halogen-free flame-retardant components and nitrogen-based halogen-free flame-retardant components are uniformly distributed in the acrylic adhesive matrix. The flame-retardant acrylic adhesive layer completely covers the surface of the release paper layer and forms a tightly bonded integral structure with the release paper layer; The flame-retardant acrylic adhesive layer is prepared by mixing and dispersing acrylic adhesive, phosphorus-based halogen-free flame-retardant components and nitrogen-based halogen-free flame-retardant components according to the measured solid content of acrylic adhesive, allowing them to stand and mature, and then coating and gradient baking to form a film. The release paper layer is the molding base for the flame-retardant acrylic adhesive layer.

2. The high-efficiency halogen-free flame-retardant tape according to claim 1, characterized in that, The addition ratio of phosphorus-based halogen-free flame retardant components is determined based on the measured solid content of acrylic adhesive, and the addition ratio of nitrogen-based halogen-free flame retardant components is determined based on the determined addition ratio of phosphorus-based halogen-free flame retardant components. The temperature and time parameters used in gradient baking to form the film are determined based on the measured film-forming characteristics of the acrylic adhesive. The calculation process is based on the film-forming characteristics of the acrylic adhesive and the physical properties of the phosphorus-based and nitrogen-based halogen-free flame-retardant components. The calculation results directly correspond to the microstructure of the flame-retardant acrylic adhesive layer.

3. The high-efficiency halogen-free flame-retardant tape according to claim 1, characterized in that, The molding process parameters of the flame-retardant acrylic adhesive layer are calculated based on the measured surface viscosity and surface tension values ​​of the flame-retardant acrylic adhesive wet film. The ratio of these two parameters is used to determine the parameters. The ratio calculation result directly corresponds to the physical state of the flame-retardant acrylic adhesive wet film, and the physical state of the flame-retardant acrylic adhesive wet film is compatible with the gradient baking process conditions.

4. The high-efficiency halogen-free flame-retardant tape according to claim 1, characterized in that, The flame-retardant structure of the high-efficiency halogen-free flame-retardant tape is composed solely of the dense and continuous structure of the flame-retardant acrylic adhesive layer. The dense and continuous structure of the flame-retardant acrylic adhesive layer is formed by a combination of mixing and dispersion, static curing and coating, and gradient baking to form a film. The microstructure of the flame-retardant acrylic adhesive layer is controlled by the ratio of phosphorus-based and nitrogen-based halogen-free flame-retardant components and their dispersion state in the acrylic adhesive matrix. The dispersion state of the two components is determined by the calculation results of the mixing and dispersion process parameters.

5. The method for preparing a high-efficiency halogen-free flame-retardant tape according to claim 1 is applicable to the high-efficiency halogen-free flame-retardant tape according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Detect the solid content of the acrylic adhesive using a solid content analyzer, calculate the addition ratio of the phosphorus-based halogen-free flame retardant component and the nitrogen-based halogen-free flame retardant component based on the solid content value, and weigh the acrylic adhesive, phosphorus-based halogen-free flame retardant component and the nitrogen-based halogen-free flame retardant component according to the calculated ratio. S2. The acrylic adhesive is heated and then mixed and dispersed in multiple stages according to the order of material addition. After dispersion, the mixed and dispersed system is allowed to stand and mature to obtain flame-retardant acrylic adhesive. S3. Apply flame-retardant acrylic adhesive to the surface of the release paper layer to form a flame-retardant acrylic adhesive wet film; detect the surface viscosity and surface tension of the flame-retardant acrylic adhesive wet film, calculate the ratio of the two test values, and determine the process parameters for gradient baking to form the film based on the calculation results. S4. The film-forming temperature range of the acrylic adhesive is detected by differential scanning calorimetry. The temperature and time parameters for gradient baking are calculated based on the film-forming temperature range. The substrate with the adhesive wet film is subjected to gradient baking according to the calculated parameters, so that the flame-retardant acrylic adhesive wet film is formed into a flame-retardant acrylic adhesive layer. S5. Surface protection treatment is applied to the molded flame-retardant acrylic adhesive layer to obtain a high-efficiency halogen-free flame-retardant tape.

6. The method for preparing a high-efficiency halogen-free flame-retardant tape according to claim 5, characterized in that, In step S1, the coefficients used to calculate and determine the addition ratio of phosphorus-based halogen-free flame retardant components and nitrogen-based halogen-free flame retardant components are all determined by actual measurements through film-forming experiments and dispersion experiments of the corresponding materials. Film formation experiments were conducted by coating acrylic adhesives with different solid contents into films, observing the pore state of the film layers, and determining the relevant parameters for non-pore film formation. The dispersion experiment involved dispersing different ratios of acrylic adhesive, phosphorus-based halogen-free flame retardant components, and nitrogen-based halogen-free flame retardant components separately, detecting the dispersion uniformity of the flame retardant components, and determining the relevant parameters for dispersion adaptation.

7. The method for preparing a high-efficiency halogen-free flame-retardant tape according to claim 5, characterized in that, In step S2, the mixing and dispersion are carried out in stages according to the order of material addition. The process parameters for each stage of dispersion are calculated and determined based on the flowability of the acrylic adhesive and the dispersion characteristics of the phosphorus-based halogen-free flame retardant component and the nitrogen-based halogen-free flame retardant component. The parameters are gradually adjusted according to the dispersion stage. The dispersion process is carried out at a uniform speed to ensure that all materials are fully mixed and there is no agglomeration. The heating parameters are calculated and determined based on the flowability characteristics of the acrylic adhesive, and the standing curing time parameters are calculated and determined based on the stability characteristics of the mixed dispersion system.

8. The high-efficiency halogen-free flame-retardant tape and its preparation method according to claim 5, characterized in that, In step S3, the coating thickness of the flame-retardant acrylic adhesive wet film is determined by calculation based on the surface characteristics of the release paper layer and the film-forming characteristics of the flame-retardant acrylic adhesive layer; the coating process is kept at a constant speed to ensure uniform wet film thickness; the static environment parameters of the flame-retardant acrylic adhesive wet film are determined by calculation based on the stability characteristics of the wet film surface viscosity and surface tension.

9. The high-efficiency halogen-free flame-retardant tape and its preparation method according to claim 5, characterized in that, In step S4, the multiple stages of gradient baking to form a film are carried out sequentially according to the film-forming reaction process of the acrylic adhesive. The stage division is determined by calculation based on the film-forming temperature range of the acrylic adhesive. The temperature and time parameters of each baking stage are determined by calculation based on the range of the film-forming temperature range and the thickness of the wet film of the adhesive. The gradient cooling rate parameter is determined by calculation based on the thermal stability characteristics of the flame-retardant acrylic adhesive layer after film formation.

10. The high-efficiency halogen-free flame-retardant tape and its preparation method according to claim 5, characterized in that, In step S5, the process parameters for surface protection treatment are determined based on the surface characteristics of the flame-retardant acrylic adhesive layer and its adaptability to the application environment. The temperature and time parameters for the protective treatment are calculated based on the surface tension of the adhesive layer and the reaction characteristics of the protective agent. The environmental parameters are kept constant during the treatment process, and the surface state of the adhesive layer after treatment directly corresponds to the calculation results.

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