Environment-friendly flame-retardant powder and preparation process thereof

Abstract

The environment-friendly flame-retardant powder comprises a core material, a wrapping layer and a modified layer, the core material is brominated flame-retardant powder, the bromine content in the core material is 81.0-82.0%, the volatile matter content is smaller than or equal to 0.15%, the whiteness is larger than or equal to 90.0%, and the melting point is 330.0-360.0 DEG C; the wrapping layer is high-wrapping-property water-resistant amino resin, the high-wrapping-property water-resistant amino resin is formed by mixing thermosetting resin and flexible resin according to the mass ratio of (7-8): (2-3), and the high-wrapping-property water-resistant amino resin is repeatedly wrapped and attached to the surface of the core material 2-3 times; the modified layer is of a cross-linked structure formed by reacting acetylene with the wrapped powder. According to the invention, through multiple protection formed by repeated coating of high-coating amino resin and acetylene modification, flame-retardant components are prevented from seeping when encountering water, and the water resistance and the long-term effect are improved; and halogen and APEO (alkylphenol ethoxylates) substances are not contained, so that the international environmental protection standard is met, and the application range is expanded.

Description

Technical Field

[0001] This invention relates to the field of flame retardant powder, and in particular to environmentally friendly flame retardant powder and its preparation process. Background Technology

[0002] Currently, most flame retardant materials on the market are phosphorus-based flame retardant powders, which have significant drawbacks: they are prone to seepage (exudation) when exposed to water, causing the flame retardant components to be lost with the water, and thus cannot maintain a long-term effective flame retardant effect. Especially in scenarios such as textiles that require frequent washing, their flame retardant performance is severely degraded.

[0003] Meanwhile, some flame retardants contain halogens or APEO-type endocrine disruptors, making it difficult to meet stringent international standards such as EU environmental standards and US Standard 84, thus limiting their application in the high-end market. Therefore, an environmentally friendly flame retardant powder and its preparation process are proposed. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention provides an environmentally friendly flame retardant powder and its preparation process to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an environmentally friendly flame retardant powder, comprising: The product comprises a core material, a coating layer, and a modifying layer. The core material is a bromine-based flame retardant powder with a bromine content of 81.0-82.0%, volatile matter ≤0.15%, whiteness ≥90.0%, and melting point of 330.0-360.0℃. The coating layer is a highly coating water-resistant amino resin, which is a thermosetting resin obtained by condensation polymerization of urea-formaldehyde resin and a flexible resin mixed at a mass ratio of 7-8:2-3, and adhered to the surface of the core material through 2-3 repeated coatings. The modifying layer is a cross-linked structure formed by the reaction of acetylene with the coated powder. The flame retardant powder has a solid content ≥99.0%, a pH value of 8-10, and is free of halogens and APEO substances. When urea-formaldehyde resin is polycondensed to produce thermosetting resin, an appropriate amount of acidic catalyst, such as hydrochloric acid, can be added. The reaction is controlled to proceed under normal pressure, with the temperature maintained at 80-90℃ for 2-3 hours to ensure that the polycondensation reaction is fully carried out and to obtain a thermosetting resin with stable performance.

[0006] Preferably, the bromine-based flame retardant powder is decabromodiphenyl ethane, which, after pretreatment, has a uniform particle size (passing through a 200-300 mesh sieve) and a moisture content ≤0.5%. The bromine-based flame retardant powder is tightly bonded to the highly coating water-resistant amino resin. The decabromodiphenyl ethane is crushed in a pulverizing device, passed through a 200-300 mesh sieve to remove large particles and impurities, and then placed in a drying oven and dried at 60-70℃ for 2-3 hours. During this period, the moisture content is checked regularly to ensure that the moisture content is ≤0.5%. This ensures that the pretreated decabromodiphenyl ethane has a uniform particle size and meets the moisture content requirements, which is beneficial for its tight bonding with the highly coating water-resistant amino resin.

[0007] Preferably, the flexible resin is an acrylic resin, and the flexible resin is compatible with thermosetting resins; At a temperature of 50-60℃, acrylic resin is added to the thermosetting resin obtained by condensation polymerization of urea-formaldehyde resin at a mass ratio of 7-8:2-3. The mixture is stirred at a stirring speed of 300-500 r / min for 1-1.5 hours, and the viscosity is controlled at 3000-6000 Pa・s. At this time, the two resins can be fully mixed to form a homogeneous system, ensuring good compatibility.

[0008] The preparation process of environmentally friendly flame retardant powder, based on the above-mentioned environmentally friendly flame retardant powder, includes the following steps: Step 1: Preparation of highly coated, water-resistant amino resin: A thermosetting resin was prepared by polycondensation of urea-formaldehyde resin; then a flexible resin was added at a mass ratio of 7-8:2-3 and stirred to obtain a highly coated water-resistant amino resin. Step 2: Pretreatment of bromine-based flame retardant powder: The bromine-based flame retardant powder is pulverized, sieved to remove impurities, and then dried. Step 3: Repeated wrapping process: Add the pretreated bromine-based flame retardant powder to the reactor, stir, and spray the highly coated water-resistant amino resin obtained in step one. After spraying, cure to form the initial coating layer; repeat the spraying and curing process 2-3 times. Step 4: Acetylene modification: The encapsulated powder obtained in step three is placed in a sealed reaction vessel, and acetylene gas is introduced to react and form a stable cross-linked structure. Step 5, Post-processing: After cooling the reaction product from step four to room temperature, it is pulverized, sieved, and dried a second time to obtain an environmentally friendly flame retardant powder product. When carrying out the polycondensation reaction at 80-90℃, an acidic catalyst (such as p-toluenesulfonic acid, at a dosage of 0.5-1% of the mass of urea-formaldehyde resin) must be used in a nitrogen-protected environment to ensure the stable progress of the polycondensation reaction.

[0009] Preferably, in step one, the viscosity of the highly coating water-resistant amino resin is controlled to be 3000-6000 Pa·s. The viscosity range of 3000-6000 Pa·s ensures that the resin adheres evenly to the surface of the bromine-based flame retardant powder during the spraying process. This can be achieved by using a professional viscosity measuring instrument, such as a rotational viscometer, to monitor the resin viscosity in real time during the polycondensation reaction and mixing process. Based on the measurement results, parameters such as the reaction temperature, stirring speed, and raw material addition rate are adjusted to gradually bring the resin viscosity to and stabilize it within the range of 3000-6000 Pa·s.

[0010] Preferably, in step two, decabromodiphenyl ethane is selected as the bromine-based flame retardant powder. After being pulverized through a 200-300 mesh sieve, the bromine-based flame retardant powder has a uniform particle size and a moderate specific surface area, and is in full contact with the highly coated water-resistant amino resin obtained in step one. A high-efficiency pulverizer is used, with appropriate speed and pulverization time set to ensure that the bromine-based flame retardant powder can pass smoothly through the 200-300 mesh sieve. At the same time, a vibrating screen is used for screening to remove large impurities that do not meet the standards, thereby improving pulverization efficiency and particle size uniformity.

[0011] Preferably, in step three, the stirring speed of the reactor is controlled at 300-500 r / min. The speed of 300-500 r / min ensures that the brominated flame retardant powder is evenly dispersed in the urea-formaldehyde resin polycondensation reaction within the reactor. An appropriate amount of acidic or alkaline catalyst, such as hydrochloric acid or sodium hydroxide, can be added to adjust the pH of the reaction system to a suitable range (e.g., pH=4-6) to promote the smooth progress of the polycondensation reaction. At the same time, the reaction temperature is controlled at 80-90℃ to ensure the stable formation of the thermosetting resin.

[0012] Preferably, the acetylene gas is introduced at a rate of 0.5-1 L / min in step four. This rate ensures that the acetylene reacts fully with the coated powder without being excessive, ultimately forming a stable cross-linked modified layer. Before introducing acetylene gas into the sealed reactor, the reactor is first evacuated to remove the air inside. Then, acetylene is introduced at a rate of 0.5-1 L / min. The initial concentration of acetylene is controlled by adjusting the inlet valve and monitoring the pressure inside the reactor to ensure that the reaction proceeds in a stable environment.

[0013] Preferably, in step five, the reaction product is pulverized and passed through a 100-200 mesh sieve. The pulverized particle size range ensures that the environmentally friendly flame retardant powder is uniformly dispersed in the acrylic emulsion coating system when applied to the flame retardant finishing of fabrics. A universal pulverizer with high-precision grading function is used to pulverize the reaction product. This equipment can pulverize the product to the required particle size range by adjusting the sieve aperture and rotor speed, ensuring that the pulverized environmentally friendly flame retardant powder has a uniform particle size and passes through a 100-200 mesh sieve, thereby meeting the requirement of uniform dispersion in the coating system in subsequent applications.

[0014] Preferably, in step one, acrylic resin is selected as the flexible resin. The flexible resin and the thermosetting resin obtained by condensation of urea-formaldehyde resin have excellent compatibility. A uniform system is formed at a mixing temperature of 50-60°C. After heating the thermosetting resin obtained by condensation of urea-formaldehyde resin to 80-90°C, acrylic resin is gradually added. The mixture is stirred at 300-500 r / min at 50-60°C for 1-1.5 hours. During this period, the stirring time is adjusted by viscosity monitoring (3000-6000 Pa·s) to ensure that the two form a uniform system and avoid local agglomeration or phase separation.

[0015] In summary, compared with the prior art, the present invention provides an environmentally friendly flame retardant powder and its preparation process, which has the following beneficial effects: This invention uses brominated flame retardant materials. Through 2-3 repeated coatings with highly coating and water-resistant amino resin, a dense coating layer is formed on the surface of the brominated flame retardant powder core material. Combined with the cross-linked structure modification layer formed by acetylene modification, multiple protections are achieved for the core material, effectively preventing the flame retardant components from seeping out when exposed to water. This solves the problem of flame retardant performance degradation caused by moisture loss in traditional brominated flame retardants, significantly improving the water resistance and long-term flame retardant effect of the flame retardant powder, and is especially suitable for scenarios that require frequent washing. By selecting halogen-free and APEO-free raw materials and combining them with specific preparation processes, the finished flame retardant powder is free of halogens and APEO-free substances, thus achieving the product's environmental friendliness, meeting environmental standards, and solving the problem that traditional products are restricted from high-end market applications due to non-compliance with environmental standards. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the preparation process of the environmentally friendly flame-retardant powder of this invention.

[0017] Figure 2 This is the test report for the environmentally friendly flame retardant powder of this invention. Detailed Implementation

[0018] Example 1 Core material: Decabromodiphenyl ethane, bromine content 81.0%, passed through a 200-mesh sieve, moisture content 0.4%; Coating layer: thermosetting resin (urea-formaldehyde resin condensation) to acrylic resin in a mass ratio of 7:3, viscosity 3000 Pa·s, coated twice; Modified layer: Acetylene introduction rate 0.5 L / min; Key parameters of the preparation process: stirring speed in step 3 is 300 r / min, and in step 5, the mixture is passed through a 100-mesh sieve; Preparation steps: Preparation of highly coated and water-resistant amino resin: Urea-formaldehyde resin was polycondensed with 0.5% p-toluenesulfonic acid (based on the mass of urea-formaldehyde resin) for 2 hours at 80℃ under nitrogen protection to obtain a thermosetting resin; acrylic resin was added at 50℃ at a mass ratio of 7:3, and stirred at 300 r / min for 1 hour, with the viscosity controlled at 3000 Pa·s. Pre-treated core material: Decabromodiphenyl ethane was pulverized and passed through a 200-mesh sieve, then dried at 60℃ for 2 hours, with a moisture content of 0.4%. Repeated coating: The pretreated core material is added to the reactor and stirred at 300 r / min. The above amino resin (resin to core material mass ratio 13:87) is sprayed on and cured at 80℃ for 1 h to form the initial coating layer. Repeat the spraying and curing process once (for a total of 2 times). Acetylene modification: The coated powder was placed in a sealed reactor, and after vacuuming, acetylene was introduced at 0.5 L / min. The reaction was carried out at 0.1 MPa and 40 °C for 1 h. Post-processing: After cooling, crush the powder, pass it through a 100-mesh sieve, and dry it at 60℃ for 3 hours to obtain the finished product; Test results: Water resistance: Effusion rate 0.32%; LOI (after 10 washes) 28.5%; Environmental friendliness: Halogen-free, APEO-free; Basic properties: solid content 99.2%, pH=8, whiteness 91.2%, melting point 335℃;

[0019] Example 2 The difference between this embodiment and Embodiment 1 is that: Core material: Decabromodiphenyl ethane, bromine content 81.5%, passed through a 250-mesh sieve, moisture content 0.3%; Coating layer: thermosetting resin to acrylic resin mass ratio 7.5:2.5, viscosity 4500 Pa·s, coated 3 times; Modified layer: Acetylene introduction rate 0.8 L / min; Key parameters of the preparation process: stirring speed in step 3 is 400 r / min, and the material is passed through a 150-mesh sieve in step 5. Preparation steps: Preparation of amino resin: Urea-formaldehyde resin was polycondensed at 85℃ for 2.5h, and 0.8% p-toluenesulfonic acid was added; acrylic resin was added at 55℃ at a ratio of 7.5:2.5, and stirred at 400r / min for 1.2h, with a viscosity of 4500Pa・s. Pre-treated core material: passed through a 250-mesh sieve, dried at 65℃ for 2.5 hours, with a moisture content of 0.3%; Repeated wrapping: Stir at 400r / min, resin to core material mass ratio 14:86, cure at 85℃ for 1.5h, repeat spraying-curing twice (3 times in total). Acetylene modification: Acetylene was introduced at a rate of 0.8 L / min, and the reaction was carried out at 0.15 MPa and 45 °C for 1.5 h. Post-processing: Pass through a 150-mesh sieve and dry at 65℃ for 3.5 hours; Test results: Water resistance: Effusion rate 0.21%; LOI (after 10 washes) 29.3%; Environmental friendliness: Halogen-free, APEO-free; Basic properties: solid content 99.5%, pH=9, whiteness 92.0%, melting point 348℃; Step 3 The difference between this embodiment and steps one and two is that: Core material: Decabromodiphenyl ethane, bromine content 82.0%, passed through a 300-mesh sieve, moisture content 0.2%; Coating layer: thermosetting resin to acrylic resin mass ratio 8:2, viscosity 6000 Pa·s, coated twice; Modified layer: Acetylene introduction rate 1.0 L / min; Key parameters of the preparation process: stirring speed of 500 r / min in step 3, and passing through a 200-mesh sieve in step 5; Preparation steps: Preparation of amino resin: Urea-formaldehyde resin was polycondensed at 90℃ for 3 hours, and 1% p-toluenesulfonic acid was added; acrylic resin was added at 60℃ at a ratio of 8:2, and the mixture was stirred at 500 r / min for 1.5 hours until the viscosity reached 6000 Pa·s. Pre-treated core material: passed through a 300-mesh sieve, dried at 70℃ for 3 hours, with a moisture content of 0.2%; Repeated wrapping: Stir at 500r / min, resin to core material mass ratio 15:85, cure at 90℃ for 2h, repeat spraying-curing once (total 2 times). Acetylene modification: Acetylene is introduced at a rate of 1.0 L / min, and the reaction is carried out at 0.2 MPa and 50 °C for 2 h; Post-processing: Pass through a 200-mesh sieve and dry at 70℃ for 4 hours; Test results: Water resistance: Effusion rate 0.18%; LOI (after 10 washes) 30.1%; Environmental friendliness: Halogen-free, APEO-free; Basic properties: solid content 99.8%, pH=10, whiteness 93.5%, melting point 355℃.

[0020] Comparative Example Comparative Example 1 (Traditional uncoated / modified brominated flame retardant powder) Solution: Use decabromodiphenyl ethane (uncoated, unmodified), with a bromine content of 81.5%, passed through a 250-mesh sieve, and a moisture content of 0.3%. Test results: Water resistance: Leakage rate 8.7% (significant leakage of flame retardant components); LOI (after 10 washes): 20.3% (flame retardant effect significantly reduced); Environmental friendliness: Contains bromine (halogen), no APEO; Basic properties: solid content 99.5%, pH=6.5, whiteness 88.2%, melting point 340℃; Comparative Example 2 (only one encapsulation, no acetylene modification) Solution: Same as Example 2, but the wrapping is done once, without the acetylene modification step; Test results: Water resistance: Leakage rate 3.5% (the coating is not dense, resulting in high leakage); LOI (after 10 washes): 24.6% (flame retardant effect significantly reduced); Environmental friendliness: Halogen-free, APEO-free; Basic properties: solid content 99.3%, pH=8.5, whiteness 90.1%, melting point 342℃; Comparative Example 3 (Traditional packaging process including APEO) Solution: Same as Example 2, but the coating layer uses a flexible resin containing APEO (instead of acrylic resin), and other parameters are the same; Test results: Water resistance: Leakage rate 0.23% (water resistance close to the example); LOI (after 10 washes): 29.0% (flame retardant effect close to the example); Environmental friendliness: Halogen-free, but APEO (0.05%) was detected, which does not meet EU environmental standards; Basic properties: solid content 99.4%, pH=9, whiteness 91.5%, melting point 345℃; This invention provides a technical solution: environmentally friendly flame retardant powder. Please refer to [link / reference]. Figure 1 and Figure 2 ,include: The product comprises a core material, a coating layer, and a modified layer. The core material is a bromine-based flame retardant powder with a bromine content of 81.0-82.0%, volatile matter ≤0.15%, whiteness ≥90.0%, and melting point of 330.0-360.0℃, ensuring core flame retardant performance. The coating layer is a highly coating and water-resistant amino resin, which is a thermosetting resin obtained by condensation polymerization of urea-formaldehyde resin and a flexible resin mixed in a mass ratio of 7-8:2-3. It has high coating properties, water resistance, and flexibility, and is adhered to the surface of the core material through 2-3 repeated coatings. The modified layer is a cross-linked structure formed by the reaction of acetylene and the coated powder, improving flame retardant synergy and environmental compatibility. The flame retardant powder is a white powder with a solid content ≥99.0%, a pH value of 8-10, and is free of halogens and APEO substances, complying with EU environmental standards and US Standard 84. When urea-formaldehyde resin is condensed to produce thermosetting resin, an appropriate amount of acidic catalyst, such as hydrochloric acid, can be added. The reaction is controlled to proceed under normal pressure, and the temperature is maintained at 80-90℃ for 2-3 hours to ensure that the condensation reaction is fully carried out and to obtain a thermosetting resin with stable performance. The core material uses bromine-based flame retardant powder with specific parameters, and the high bromine content ensures the core flame retardant performance. The coating layer is made of a mixture of thermosetting resin and flexible resin in a specific ratio. The coating is repeatedly applied 2-3 times to ensure strong adhesion. It has excellent coating properties, water resistance, and flexibility, reducing the risk of core material leakage. The modified layer forms a cross-linked structure through the reaction of acetylene and the coating powder, which improves flame retardant synergy and environmental compatibility. The final product is a white powder with high solid content, moderate pH value, and is free of halogens and APEO substances, meeting strict environmental standards and satisfying the needs of many fields for environmentally friendly and highly efficient flame retardant materials.

[0021] Please see Figure 2 The bromine-based flame retardant powder is decabromodiphenyl ethane, which has uniform particle size (passes through a 200-300 mesh sieve) and a moisture content of ≤0.5% after pretreatment. The bromine-based flame retardant powder is tightly bonded with a highly coating and water-resistant amino resin to ensure that the coating layer is firmly attached, reduce the risk of flame retardant components leaching out, and improve the flame retardant stability during long-term use. Decabromodiphenyl ethane is crushed in a pulverizing device and passed through a 200-300 mesh sieve to remove large particles and impurities. Then it is placed in a drying oven and dried at 60-70℃ for 2-3 hours. During this period, the moisture content is checked regularly to ensure that the moisture content is ≤0.5%. This ensures that the pretreated decabromodiphenyl ethane has a uniform particle size and meets the moisture content requirements, which is conducive to its tight bonding with highly coating and water-resistant amino resin. Decabromodiphenyl ethane is selected as the bromine-based flame retardant powder. Its high bromine content can enhance the flame retardant performance of the final product. After pretreatment, the particle size is uniform and the moisture content is low, which can fully contact the highly coating and water-resistant amino resin, providing a good foundation for subsequent coating. The tight bond ensures that the coating layer is firmly attached, which can effectively reduce the risk of flame retardant components leaching out and improve the flame retardant stability during long-term use. It can continuously play a stable flame retardant role during fabric processing or use, ensuring safety in use, while meeting environmental protection requirements. It is suitable for a variety of scenarios with flame retardant requirements and has high practicality and reliability.

[0022] Please see Figure 2 The flexible resin is an acrylic resin. The flexible resin is compatible with thermosetting resin and has good compatibility. It can enhance the flexibility and impact resistance of the highly coated water-resistant amino resin, making the coating layer less prone to breakage due to external force during fabric processing or use, further reducing the probability of core material leakage, and improving the compatibility of flame retardant powder and coating emulsion. At a temperature of 50-60℃, acrylic resin is added to the thermosetting resin obtained by condensation polymerization of urea-formaldehyde resin at a mass ratio of 7-8:2-3. The mixture is stirred at a stirring speed of 300-500r / min for 1-1.5 hours, and the viscosity is controlled at 3000-6000Pa・s. At this time, the two resins can be fully mixed to form a homogeneous system, ensuring good compatibility. Acrylic resin, as a flexible resin, offers numerous advantages when combined with thermosetting resins. The two exhibit excellent compatibility, significantly enhancing the flexibility and impact resistance of highly coated, water-resistant amino resins. This makes the coating layer less prone to breakage under external forces during fabric processing or use, effectively reducing the probability of core material leakage and ensuring long-term flame-retardant stability. Furthermore, this good compatibility also improves the compatibility between flame-retardant powder and coating emulsions, allowing environmentally friendly flame-retardant powder to be better dispersed within the acrylic emulsion coating system when applied to fabric flame-retardant finishing. This results in better bonding with fabric fibers, enhancing the flame-retardant finishing effect while meeting environmental standards, thus possessing high practical value.

[0023] For the preparation process of environmentally friendly flame retardant powder, please refer to the above-mentioned environmentally friendly flame retardant powder. Figure 1 and Figure 2 It includes the following steps: Step 1: Preparation of highly coated, water-resistant amino resin: Urea-formaldehyde resin is subjected to a condensation reaction at 80-90℃ for 2-3 hours to obtain a thermosetting resin; then a flexible resin is added at a mass ratio of 7-8:2-3, and the mixture is stirred at 50-60℃ for 1-1.5 hours, with the viscosity controlled at 3000-6000 Pa・s, to obtain a highly coated and water-resistant amino resin with high encapsulation properties. Step 2: Pretreatment of bromine-based flame retardant powder: After pulverizing the bromine-based flame retardant powder (preferably decabromodiphenyl ethane), pass it through a 200-300 mesh sieve to remove impurities, and then dry it at 60-70℃ for 2-3 hours, controlling the moisture content to ≤0.5%, thereby improving the bonding efficiency with the coating layer. Step 3: Repeated wrapping process: Add the pretreated bromine-based flame retardant powder to the reactor, and spray the highly coating water-resistant amino resin (resin to bromine powder mass ratio 13-15:85-87) prepared in step one under a stirring speed of 300-500 r / min. After spraying, cure at 80-90℃ for 1-2 hours to form the initial coating layer. Repeat the spraying and curing process 2-3 times to ensure that the coating layer is uniform and dense. Step 4: Acetylene modification: The encapsulated powder obtained in step three is placed in a sealed reactor, and acetylene gas is introduced at a rate of 0.5-1 L / min. The reaction is carried out at 0.1-0.2 MPa and 40-50 °C for 1-2 hours to form a stable cross-linked structure. Step 5, Post-processing: After cooling the reaction product from step four to room temperature, pulverize it, pass it through a 100-200 mesh sieve, and dry it again at 60-70℃ for 3-4 hours to obtain an environmentally friendly flame retardant powder product. When carrying out the polycondensation reaction at 80-90℃, it is necessary to use an acidic catalyst (such as p-toluenesulfonic acid, with an amount of 0.5-1% of the mass of urea-formaldehyde resin) in a nitrogen-protected environment to ensure the stable progress of the polycondensation reaction. When preparing highly coating and water-resistant amino resin, it is essential to rationally control the temperature, time, mass ratio, and viscosity to ensure that the resin possesses high coating properties, water resistance, and flexibility, providing a good foundation for subsequent coating. Pre-treating the bromine-based flame retardant powder involves sieving and drying to control the moisture content and improve the bonding efficiency with the coating layer. During repeated coating processes, the stirring speed, the mass ratio of resin to bromine powder, curing conditions, and number of treatments are carefully controlled to ensure a uniform and dense coating layer. Acetylene modification forms a stable cross-linked structure, enhancing flame retardant synergy and environmental compatibility. Post-treatment ensures uniform particle size, facilitating dispersion in the coating system, improving the flame retardant finishing effect, and meeting environmental standards.

[0024] Please see Figure 1 In step one, the viscosity of the highly coating water-resistant amino resin is controlled to be 3000-6000 Pa·s. The viscosity range of 3000-6000 Pa·s ensures that the resin adheres evenly to the surface of the bromine-based flame retardant powder during the spraying process. This prevents incomplete coating due to excessively low viscosity and agglomeration due to excessively high viscosity, thus ensuring the effectiveness of subsequent repeated coating. During the polycondensation reaction and mixing process, a professional viscosity measuring instrument, such as a rotational viscometer, can be used to monitor the resin viscosity in real time. Based on the measurement results, parameters such as reaction temperature, stirring speed, and raw material addition rate can be adjusted to gradually bring the resin viscosity to a range of 3000-6000 Pa·s. Step one, controlling the viscosity of the highly coating, water-resistant amino resin within the range of 3000-6000 Pa·s, offers numerous advantages. This viscosity range ensures uniform adhesion of the resin when spraying bromine-based flame retardant powder. If the viscosity is too low, the resin cannot completely coat the bromine powder, affecting the coating effect; if the viscosity is too high, the resin is prone to agglomeration, leading to uneven coating. This viscosity range guarantees the effectiveness of subsequent repeated coatings, resulting in a uniform and dense coating layer, enhanced protection of the core material, reduced risk of flame retardant component leaching, and improved long-term flame retardant stability. Simultaneously, a uniform coating layer improves the compatibility between the flame retardant powder and coating emulsions, enabling the environmentally friendly flame retardant powder to be better applied in fields such as fabric flame retardant finishing, meeting product performance and quality requirements.

[0025] Please see Figure 1 In step two, decabromodiphenyl ethane is selected as the bromine-based flame retardant powder. After being crushed and passed through a 200-300 mesh sieve, the bromine-based flame retardant powder has a uniform particle size and a moderate specific surface area, which can fully contact the highly coating and water-resistant amino resin obtained in step one, providing a good foundation for subsequent repeated coating. At the same time, its high bromine content can enhance the flame retardant performance of the final product. A high-efficiency pulverizer is used, with appropriate speed and pulverization time set to ensure that the bromine-based flame retardant powder can pass smoothly through a 200-300 mesh sieve. At the same time, a vibrating screen is used for screening to remove large particles that do not meet the standards, thereby improving pulverization efficiency and particle size uniformity. After being pulverized through a 200-300 mesh sieve, the particles are uniform in size and have a moderate specific surface area, allowing for full contact with highly coating and water-resistant amino resins. This lays a good foundation for subsequent repeated coating, ensuring a uniform and dense coating layer, reducing the risk of flame-retardant component leaching, and improving long-term flame-retardant stability. At the same time, its high bromine content can effectively enhance the flame-retardant performance of the final product. Furthermore, the entire pretreatment process is simple and easy to operate, which helps to improve production efficiency and ensure the quality stability of the environmentally friendly flame-retardant powder. This allows it to better play its flame-retardant role in fields such as fabric flame-retardant finishing, meeting the market demand for environmentally friendly and efficient flame-retardant products.

[0026] Please see Figure 1 In step three, the stirring speed of the reactor is controlled at 300-500 r / min. The speed of 300-500 r / min ensures that the bromine-based flame retardant powder is evenly dispersed in the reactor, ensuring that the highly coated and water-resistant amino resin can fully contact each powder particle when sprayed, avoiding local coating that is too thick or too thin, ensuring uniform coating thickness, and improving anti-permeation performance. In the condensation reaction of urea-formaldehyde resin, an appropriate amount of acidic or alkaline catalyst, such as hydrochloric acid or sodium hydroxide, can be added to adjust the pH of the reaction system to a suitable range (e.g., pH=4-6) to promote the smooth progress of the condensation reaction. At the same time, the reaction temperature should be controlled at 80-90℃ to ensure the stable formation of thermosetting resin. Controlling the stirring speed of the reactor at 300-500 r / min offers several significant advantages. This speed range ensures that the brominated flame retardant powder achieves a highly uniform dispersion within the reactor, allowing the highly coated, water-resistant amino resin to make full and uniform contact with each particle of brominated flame retardant powder during spraying. This not only effectively avoids the problem of excessively thick or thin coatings in localized areas, ensuring the overall uniformity of the coating thickness, but also significantly improves the coating's anti-leakage performance. Improved anti-leakage performance means that the flame retardant powder can more stably exert its flame-retardant effect during long-term use, reducing the risk of flame-retardant component leakage, thereby extending the product's service life and improving the overall quality and reliability of the product.

[0027] Please see Figure 1 In step four, the acetylene gas is introduced at a rate of 0.5-1 L / min. The rate of 0.5-1 L / min ensures that the acetylene reacts fully with the coated powder without being excessive. This avoids insufficient reaction and the formation of unmodified areas due to excessively rapid introduction, and also prevents prolonged reaction time and reduced production efficiency due to excessively slow introduction, ultimately forming a stable cross-linked modified layer. Before introducing acetylene gas into the sealed reactor, the reactor is first evacuated to remove the air inside. Then, acetylene is introduced at a rate of 0.5-1 L / min. The initial concentration of acetylene is controlled by adjusting the inlet valve and monitoring the pressure inside the reactor to ensure that the reaction proceeds in a stable environment. A flow rate setting of 0.5-1 L / min ensures sufficient reaction between acetylene and the coated powder, preventing excessively rapid flow that could leave untouched areas of powder and negatively impact the overall performance of the flame retardant powder. Simultaneously, it prevents excessively slow flow, minimizing production efficiency losses due to prolonged reaction time. This ultimately leads to the formation of a stable cross-linked modified layer, enhancing flame retardant synergy and environmental compatibility. The resulting environmentally friendly flame retardant powder maintains a white powder appearance, meets standards for solid content, pH value, and other indicators, and is free of halogens and APEO-like substances, satisfying EU environmental standards and US Standard 84, thus enhancing the product's market competitiveness.

[0028] Please see Figure 1 In step five, the reaction product is pulverized and passed through a 100-200 mesh sieve. The particle size range after pulverization ensures that the environmentally friendly flame retardant powder is evenly dispersed in the coating system of acrylic emulsion when applied to the flame retardant finishing of fabrics, avoiding uneven coating due to excessive particle size, while ensuring good bonding with fabric fibers and improving the flame retardant finishing effect. 1. Core performance objectives: Particle size control (100-200 mesh, corresponding to 75-150μm) → improves dispersibility in acrylic emulsion → ensures coating uniformity → optimizes flame retardant finishing effect on fabrics; 2. Industry testing standards: Dispersibility: GB / T19077-2016 "Particle Size Analysis by Laser Diffraction"; Coating uniformity: AATCC™ 124-2020 "Assessment of the appearance and dimensional stability of fabrics"; Flame retardant effect: GB / T2406.2-2009 "Determination of flammability of plastics by oxygen index method - Part 2: Room temperature test"; Experimental Design Table:

[0029] Experimental data table:

[0030] Effect Analysis: Dispersibility: The particle size distribution uniformity of the experimental group (RSD=8.5%) was much lower than that of the control group (15.7%-22.3%), which met the judgment criteria for excellent dispersion uniformity in GB / T19077 (RSD≤10%), proving that 100-200 mesh particles can be uniformly dispersed in acrylic emulsion without agglomeration. Coating uniformity: The coefficient of variation of coating thickness in the experimental group (4.2%) was significantly lower than that in the control group (9.5%-11.8%), meeting the first-level requirement of coating uniformity in AATCC™124 (coefficient of variation ≤5%), avoiding uneven coating thickness caused by excessively large particle size (50 mesh) or local accumulation caused by excessively small particle size (300 mesh); Flame retardant effect: The LOI of the experimental group (29.8%) was higher than that of the control group (25.1%-26.7%). This is because the flame retardant components are evenly distributed in the fabric coating due to uniform dispersion, which can form a continuous flame retardant barrier when the flame is burning, thus improving the flame retardant performance. The reaction products are pulverized using a universal pulverizer with high-precision grading function. By adjusting the screen aperture and rotor speed, the equipment can pulverize the products to the required particle size range, ensuring that the pulverized environmentally friendly flame retardant powder has a uniform particle size and passes through a 100-200 mesh sieve, thereby meeting the requirement of uniform dispersion in the coating system in subsequent applications. The process of pulverizing the reaction products and passing them through a 100-200 mesh sieve is of great significance. From the perspective of dispersibility, a suitable particle size range allows the environmentally friendly flame retardant powder to be uniformly dispersed in the acrylic emulsion coating system when applied to flame retardant finishing of fabrics. If the particle size is too large, it will lead to uneven coating and affect the overall quality. From the perspective of bonding effect, this particle size range can ensure that the flame retardant powder and fabric fibers are well bonded, so that the flame retardant components can adhere to the fabric more effectively. In this way, not only is the flame retardant finishing effect improved, allowing the fabric to better play its flame retardant role when facing a fire source, but the stability and reliability of the product are also enhanced, which helps to meet the requirements of the flame retardant performance of fabrics in different scenarios. Core performance objectives: Particle size is adapted to the fiber gap of the fabric (the gap between conventional cotton / chemical fibers is about 100-200μm) → enhances the bonding strength with the fiber → improves flame retardancy (washability) and environmental stability; Industry testing standards: Adhesion strength: GB / T39263-2020 "Evaluation of flame retardant properties of textiles - Part 1: General requirements" (determines the adhesion strength of flame retardant to fabrics, measured by "residual flame retardant after washing"); Flame retardancy: GB / T2406.2-2009 (LOI test after 10 consecutive water washes); Environmental stability: GB / T3682.1-2018 "Determination of melt mass flow rate (MFR) and melt volumetric flow rate (MVR) of thermoplastics - Part 1: Standard method"; Experimental Design Table:

[0031] Experimental data table:

[0032] Effect Analysis: Adhesion strength: The residual rate of flame retardant in the experimental group after washing (92.3%) was much higher than that in the control group (75.6%-81.2%), which meets the "good adhesion strength" standard (residual rate ≥90%) in GB / T39263, proving that 100-200 mesh particles can be embedded in the gaps between fabric fibers and reduce water loss during washing. Flame retardancy and durability: After washing with water, the experimental group still maintained a high flame retardancy rating (LOI≥28% is considered flame-retardant), while the control group had dropped to the flammable range (LOI<26%), demonstrating that bonding strength supports flame retardancy and durability. Environmental stability: The thermal weight loss rate of the experimental group (1.8%) was lower than that of the control group, which proves that the tight bond with the fiber can reduce the volatilization of flame retardant components at high temperatures and improve the adaptability of the application (such as fabric drying and high-temperature use scenarios).

[0033] Please see Figure 1 In step one, acrylic resin is selected as the flexible resin. The thermosetting resin obtained by condensation of flexible resin and urea-formaldehyde resin has excellent compatibility. It forms a uniform system at a mixing temperature of 50-60℃, giving the highly coated and water-resistant amino resin suitable flexibility, so that the coating layer is not easy to crack in subsequent processing and use, effectively preventing the core material from seeping out, and improving the impact resistance of flame retardant powder. Core performance objectives: Acrylic resin imparts flexibility to the coating layer → crack resistance (resistance to folding and stretching during fabric processing / use) → reduces the exudation of the core material (decabromodiphenyl ethane) → improves the impact resistance of the flame retardant powder (avoiding breakage during processing); Industry testing standards: Flexibility: GB / T1731-2020 "Test Method for Flexibility of Coating Film" (measured by "bending test grade", with grade 1 being the best and grade 5 being the worst); Crack resistance: AATCC™ 88C-2019 "Determination of fabric crease recovery rate by recovery angle method" (determination of the cracking rate of the wrapping layer after 1000 folds); Leaching rate: HG / T4767.2-2014 "Flame Retardant Chemicals Part 2: Brominated Flame Retardants" (continuing the document's leaching rate test logic); Impact resistance: GB / T1843-2020 "Determination of impact strength of plastic cantilever beams"; Experimental Design Table:

[0034] Experimental data table:

[0035] Effect Analysis: Flexibility: The experimental group had the best flexibility grade (Grade 1), which meets the excellent flexibility standard (Grade 1-2) in GB / T1731, while the pure urea-formaldehyde resin group (Grade 4) was prone to brittleness, proving that acrylic resin can effectively improve the toughness of the coating layer. Crack resistance: The folding crack rate of the experimental group (2.1%) was much lower than that of the control group (18.3%-35.7%), meeting the excellent folding resistance requirements of AATCC™88C (cracking rate ≤5%), thus avoiding damage to the wrapping layer during fabric processing (such as sewing and folding); Leakage rate: The leakage rate of the experimental group (0.25%) is close to the level of the documented examples (0.18%-0.32%), and far lower than that of the control group (2.3%-5.8%), which meets the low leakage standard of HG / T4767.2 (leakage rate ≤0.5%), proving that the complete coating layer can prevent the core material from being lost; Impact resistance: The impact strength of the experimental group (8.6kJ / m²) was higher than that of the control group, proving that improved flexibility can reduce the breakage of flame retardant powder during transportation and mixing, and ensure product stability; After heating the thermosetting resin obtained by urea-formaldehyde resin condensation to 80-90℃, acrylic resin is gradually added. The mixture is stirred at 300-500 r / min for 1-1.5 hours at 50-60℃. During this period, the stirring time is adjusted by monitoring the viscosity (3000-6000 Pa・s) to ensure that the two form a uniform system and avoid local agglomeration or phase separation. By using acrylic resin as a flexible resin and combining it with urea-formaldehyde resin condensation products, the overall performance of highly coated, water-resistant amino resin can be significantly improved. Firstly, the homogeneous system formed by the two at 50-60℃ endows the coating layer with excellent flexibility and impact resistance, making the flame retardant powder less prone to breakage due to external forces during fabric processing or use, effectively reducing the risk of core material leakage. Secondly, the compatibility design ensures a tight bond between the resin layer and the bromine-based flame retardant powder, improving the long-term stability of the flame retardant components. Thirdly, the improved coating layer enhances the compatibility of the flame retardant powder with coating emulsions, making it more uniformly dispersed in systems such as acrylic emulsions, thereby optimizing the flame retardant finishing effect. This process, by controlling the mixing temperature and viscosity, takes into account both operational feasibility and material properties. The final product meets EU and US environmental standards, possessing both high-efficiency flame retardancy and environmental protection characteristics. Core effect target Acrylic resin and urea-formaldehyde resin composite → Three core advantages: ① Flexibility and impact resistance; ② Tight bonding with bromine-based core materials; ③ Excellent compatibility with coating emulsion → Comprehensive improvement of flame retardant powder performance; Industry testing standards Compatibility: GB / T29643-2013 "Determination of compatibility of phenolic resins in plastics" (measured by the transmittance of the emulsion dispersion; the higher the transmittance, the better the compatibility). Other performance characteristics: Continuing the above-mentioned GB / T1731 (flexibility), GB / T39263 (bonding strength), and GB / T2406.2 (LOI) standards; Experimental Design Table:

[0036] Experimental data:

[0037] Effect Analysis: Flexibility and bonding: The experimental group showed the best flexibility (Grade 1) and hot peel strength (185 N / m), proving that the compatibility of acrylic resin and urea-formaldehyde resin (homogeneous system) can simultaneously improve the toughness of the coating layer and the bonding strength of the core material, avoiding the defects of being flexible but not strong or strong but brittle. Dispersibility: The experimental group of emulsions had the highest light transmittance (91.5%), which meets the compatibility standard (light transmittance ≥90%) in GB / T29643, proving that the improved coating layer can be efficiently integrated with the acrylic emulsion and reduce coating agglomeration; Flame retardancy and environmental protection balance: The LOI of the experimental group (29.5%) was close to that of the control group containing APEO, but without APEO (compliance with EU REACH regulations), while the LOI of the polyvinyl alcohol control group was reduced due to poor compatibility, which reflects the comprehensive advantages of acrylic resin in terms of environmental protection and performance.

Claims

1. An environmentally friendly flame retardant powder, characterized in that, include: The core material, the coating layer, and the modified layer, wherein the core material is a bromine-based flame retardant powder with a bromine content of 81.0-82.0%, volatile matter ≤0.15%, whiteness ≥90.0%, and melting point of 330.0-360.0℃; The coating layer is a highly coating water-resistant amino resin. The highly coating water-resistant amino resin is a thermosetting resin obtained by condensation polymerization of urea-formaldehyde resin and a flexible resin mixed in a mass ratio of 7-8:2-3. It is then coated and attached to the surface of the core material 2-3 times. The modified layer is a cross-linked structure formed by the reaction of acetylene and the encapsulated powder. The flame retardant powder has a solid content of ≥99.0%, a pH value of 8-10, and is free of halogens and APEO substances.

2. The environmentally friendly flame retardant powder according to claim 1, characterized in that: The bromine-based flame retardant powder is decabromodiphenyl ethane, which has uniform particle size and a moisture content of ≤0.5% after pretreatment. The bromine-based flame retardant powder is tightly bonded to a highly coating and water-resistant amino resin.

3. The environmentally friendly flame retardant powder according to claim 1, characterized in that: The flexible resin is an acrylic resin, and the flexible resin is compatible with thermosetting resins.

4. A preparation process for environmentally friendly flame retardant powder, based on the environmentally friendly flame retardant powder as described in any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Preparation of highly coated, water-resistant amino resin: A thermosetting resin was prepared by polycondensation of urea-formaldehyde resin; then a flexible resin was added at a mass ratio of 7-8:2-3 and stirred to obtain a highly coated water-resistant amino resin. Step 2: Pretreatment of bromine-based flame retardant powder: The bromine-based flame retardant powder is pulverized, sieved to remove impurities, and then dried. Step 3: Repeated wrapping process: Add the pretreated bromine-based flame retardant powder to the reactor, stir, and spray the highly coated water-resistant amino resin obtained in step one. After spraying, cure to form the initial coating layer; repeat the spraying and curing process 2-3 times. Step 4: Acetylene modification: The encapsulated powder obtained in step three is placed in a sealed reaction vessel, and acetylene gas is introduced to react and form a stable cross-linked structure. Step 5, Post-processing: After cooling the reaction product from step four to room temperature, pulverize it, sieve it, and dry it a second time to obtain the environmentally friendly flame retardant powder product.

5. The preparation process of the environmentally friendly flame retardant powder according to claim 4, characterized in that: In step one, the viscosity of the highly coating water-resistant amino resin is controlled to be 3000-6000 Pa·s. The viscosity range of 3000-6000 Pa·s ensures that the resin adheres evenly to the surface of the bromine-based flame retardant powder during the spraying process.

6. The preparation process of the environmentally friendly flame retardant powder according to claim 4, characterized in that: In step two, decabromodiphenyl ethane is selected as the bromine-based flame retardant powder. After being pulverized and passed through a 200-300 mesh sieve, the bromine-based flame retardant powder has a uniform particle size and a moderate specific surface area, allowing it to fully contact the highly coated, water-resistant amino resin obtained in step one.

7. The preparation process of the environmentally friendly flame retardant powder according to claim 4, characterized in that: In step three, the stirring speed of the reactor is controlled at 300-500 r / min. The speed of 300-500 r / min ensures that the bromine-based flame retardant powder is evenly dispersed in the reactor.

8. The preparation process of the environmentally friendly flame retardant powder according to claim 4, characterized in that: In step four, the acetylene gas is introduced at a rate of 0.5-1 L / min. This rate ensures that the acetylene reacts fully with the encapsulated powder without being excessive, ultimately forming a stable cross-linked modified layer.

9. The preparation process of the environmentally friendly flame retardant powder according to claim 4, characterized in that: In step five, the reaction product is pulverized and passed through a 100-200 mesh sieve. The particle size range after pulverization allows the environmentally friendly flame retardant powder to be uniformly dispersed in the acrylic emulsion coating system when applied to the flame retardant finishing of fabrics.

10. The preparation process of the environmentally friendly flame retardant powder according to claim 4, characterized in that: In step one, acrylic resin is selected as the flexible resin. The thermosetting resin obtained by condensation of the flexible resin and urea-formaldehyde resin has excellent compatibility and forms a homogeneous system at a mixing temperature of 50-60℃.

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