Formyloxy polysilazane as well as preparation method and application thereof

Abstract

The invention provides formyloxy polysilazane as well as a preparation method and application thereof. The formyloxy polysilazane has a structure as shown in a general formula (I), and R1, R2 and R3 are specific groups; n / (m + n) is equal to 0.1-0.7. The formyloxy polysilazane disclosed by the invention has unique molecular design, is decomposed to generate carbon dioxide during combustion, has an excellent flame-retardant effect, can be used as a macromolecular flame retardant, and does not release toxic or corrosive gas; and the nitrogen silane has a ceramic effect at a high temperature, so that the nitrogen silane can play a role in heat insulation and dripping resistance, and has a wide application prospect in the field of material flame retardance.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer flame retardants, and in particular to a formyloxy polysilazane, a preparation method and application thereof. Background Art

[0002] Polymer materials are favored by various fields due to their unique properties and wide applicability. In many application fields, materials are required to be flame retardant, which puts forward requirements for polymer materials: not only basic mechanical properties and excellent high temperature resistance, but also excellent flame retardant properties are required to ensure safety and reliability under extreme conditions.

[0003] To meet this challenge, the research and development direction of traditional flame retardants is mainly focused on halogen and phosphorus flame retardants. For example, the Chinese patent with publication number CN 116813915 A discloses a polyphosphinosilazane polymer flame retardant with a specific structure and its preparation method and application. The polyphosphinosilazane polymer flame retardant will produce phosphoric acid substances during the combustion process, which will promote the rapid dehydration and carbonization of the polymer surface, forming a carbonized layer or a non-combustible layer covering the surface of the substrate material. At the same time, the P / N / Si multi-element in the structure can also play a synergistic flame retardant role. Because the unsaturated double bond and NH bond serve as active sites, the polyphosphinosilazane polymer flame retardant molecules are easy to self-polymerize, and the polyphosphinosilazane polymer flame retardant molecules can be directly used as flame-retardant polymer coatings after self-polymerization. These flame retardants enhance the flame retardancy of the material to a certain extent, but they will produce a large amount of toxic and corrosive gases, such as hydrogen halides and phosphine, when burned, which cause serious harm to the environment and human health. In addition, the use of halogen and phosphorus flame retardants also leads to aging and corrosion of building materials, increasing the cost and difficulty of subsequent maintenance, which is not in line with the increasingly strong global environmental protection and safety demands. In the prior art, the paper "Reactions of CO2 and CO2 Analogs (CXYwith X, Y=O, S, NR) with Reagents Containing Si–H and Si–N Units" (http: / / dx.doi.org / 10.1016 / B978-0-12-420221-4.00004-4) points out that CO2 is inserted into the Si-N bond to synthesize compounds containing Si-O-CO-NR structure. Where R represents any alkyl or aryl chain.

[0004] Polysilazane flame retardant is a new type of flame retardant with Si-N bond as the main chain and organic or inorganic groups as the side chain. It has the advantages of being halogen-free, low smoke, and highly efficient, and is a representative of environmentally friendly flame retardants. However, polysilazane flame retardant has the problem of unsatisfactory flame retardant effect, especially in extreme conditions, which makes the advantages of this material in the field of flame retardancy not fully utilized. Therefore, further improving the flame retardancy of nitrogen silane flame retardant has become a key point for material breakthrough. Summary of the invention

[0005] In order to solve the deficiencies of the prior art, specifically the technical problems that polymer flame retardants have poor flame retardancy and are not environmentally friendly, the present invention introduces formyloxy groups into the main chain of polysilazane by redesigning the segment structure of polysilazane, and provides a formyloxy polysilazane, a preparation method and application thereof. Using it as a polymer flame retardant can effectively improve the flame retardant properties of the material, not only can it effectively suppress the spread of flames when a fire occurs, but also requires that the impact on the environment and human health during use and combustion is minimized, so that it is more in line with green and safe application requirements.

[0006] In order to achieve the above object, according to one aspect of the present invention, a formyloxy polysilazane is provided, having a structure shown in general formula (I):

[0007]

[0008] General formula (I);

[0009] Wherein, R1 and R2 are independently selected from one of hydrogen, C1~C10 straight chain or branched alkyl, C2~C10 straight chain or branched alkenyl, C6~C20 substituted or unsubstituted aryl, and C1~C10 secondary amine, and at least one of R1 and R2 is selected from one of hydrogen and C2~C10 straight chain or branched alkenyl; R3 is selected from one of hydrogen, C1~C10 straight chain or branched alkyl, C2~C10 straight chain or branched alkenyl, and C6~C20 substituted or unsubstituted aryl; m and n are independently integers of 1 to 10, and n / (m+n)=0.1~0.7.

[0010] Further, R1 and R2 are independently selected from one of hydrogen, a C1-C5 straight chain or branched alkyl group, a C2-C6 straight chain or branched alkenyl group, a phenyl group, and a C1-C6 secondary amine group, and at least one of R1 and R2 is selected from one of hydrogen, and a C2-C6 straight chain or branched alkenyl group, and / or R3 is selected from one of hydrogen, a C1-C5 straight chain or branched alkyl group, a C2-C6 straight chain or branched alkenyl group, and a phenyl group.

[0011] Further, R1 and R2 are independently selected from one of hydrogen, methyl, ethyl, vinyl, allyl, phenyl, and a secondary amine of C2 to C6, and at least one of R1 and R2 is selected from one of hydrogen, vinyl, and allyl, and / or; R3 is selected from one of hydrogen, and a straight or branched alkyl of C1 to C5.

[0012] Furthermore, m and n are each independently an integer from 1 to 5.

[0013] Furthermore, in the formyloxy polysilazane, R1 is hydrogen, R2 is methyl, R3 is hydrogen, m is 3, and n is 4; or, in the formyloxy polysilazane, R1 is methyl, R2 is vinyl, R3 is hydrogen, m is 2, and n is 2.

[0014] Furthermore, the viscosity of the formyloxy polysilazane is 500-3000 cps, and / or the residual carbon rate of the formyloxy polysilazane is 40-70%.

[0015] According to another aspect of the present invention, a method for preparing formyloxypolysilazane is provided, comprising the following steps: introducing carbon dioxide into a closed container having a volume of 4.5 to 5.5 L and comprising a catalyst, an organic solvent and 1 kg of polysilazane to carry out a first addition reaction, and controlling the initial pressure of carbon dioxide in the reaction system to be 0.6 to 1.6 MPa; then stopping the introduction of carbon dioxide and carrying out a second addition reaction to obtain a product system comprising formyloxypolysilazane; the temperature of the first addition reaction is 30 to 45° C. and the time is 1 to 1.5 h; the temperature of the second addition reaction is 25 to 30° C. and the time is 1 to 2 h;

[0016] Wherein, polysilazane has a structure shown in general formula (II),

[0017] ;

[0018] General formula (II);

[0019] wherein R1, R2 and R3 are as defined above, and p is an integer from 1 to 20.

[0020] Furthermore, the weight ratio of polysilazane to the organic solvent is 1:(1-10).

[0021] Furthermore, the catalyst is a transition metal catalyst, and / or the catalyst participates in the reaction process in a surface-loaded form or a homogeneous form, and / or the organic solvent is an aprotic solvent.

[0022] Furthermore, the preparation method also includes the following steps: centrifuging, filtering and reducing the pressure of the product system in sequence to obtain formyloxy polysilazane.

[0023] According to another aspect of the present invention, a flame retardant material is provided, wherein the formyloxy polysilazane is mixed with a base material, cured and extruded to obtain the flame retardant material, wherein the base material comprises one or more of glass fiber, polymer masterbatch and metal casting.

[0024] Furthermore, flame retardant materials are capable of releasing carbon dioxide when burned.

[0025] Compared with the prior art, the formyloxy polysilazane polymer flame retardant of the present invention has the following advantages:

[0026] 1. With its innovative molecular structure and flame retardant mechanism, it can significantly improve the limiting oxygen index, combustion level, residual carbon rate of the material and improve flame retardancy;

[0027] 2. It can achieve ceramicization through chemical bonding to form an efficient flame retardant layer, which can prevent dripping and flame spread, and have a profound impact on the fire safety of polymer materials and environmental sustainable development;

[0028] 3. It has high reactivity and can react with groups containing active hydrogen to improve compatibility with base materials, thereby improving the durability of the flame retardant effect and the overall performance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0030] Figure 1 shows the infrared absorption curve of the polysilazane of Example 1 of the present invention;

[0031] Figure 2 shows the infrared absorption curve of the formyloxy polysilazane of Example 1 of the present invention;

[0032] Figure 3 shows the infrared absorption curve of the polysilazane of Example 7 of the present invention; and

[0033] Figure 4 The infrared absorption curve of the formyloxy polysilazane of Example 7 of the present invention is shown. DETAILED DESCRIPTION

[0034] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0035] As described in the background of the present invention, the existing polymer flame retardants have the problems of poor flame retardancy and environmental pollution. In order to solve the above problems, in a typical embodiment of the present invention, a formyloxy polysilazane is provided, and the formyloxy polysilazane has a structure shown in general formula (I),

[0036] ;

[0037] General formula (I);

[0038] Wherein, R1 and R2 are independently selected from one of hydrogen, C1~C10 straight chain or branched alkyl, C2~C10 straight chain or branched alkenyl, C6~C20 substituted or unsubstituted aryl, and C1~C10 secondary amine, and at least one of R1 and R2 is selected from one of hydrogen and C2~C10 straight chain or branched alkenyl; R3 is selected from one of hydrogen, C1~C10 straight chain or branched alkyl, C2~C10 straight chain or branched alkenyl, and C6~C20 substituted or unsubstituted aryl; m and n are independently integers of 1 to 10, and n / (m+n)=0.1~0.7.

[0039] The silicon atoms and nitrogen atoms in the formyloxy polysilazane polymer of the present application are alternately connected in series to construct a ring-shaped and linear polymer skeleton, which ensures the basic structural stability and excellent heat resistance of the material. The formyloxy group, unsaturated double bond or hydrogen bond on the side chain serves as an active group, which gives the molecular level reactivity and can self-polymerize to form a dense flame retardant layer under certain conditions. In addition, the presence of polar NH bonds in the polysilazane structure can enhance the compatibility with the material. The Si-NH-Si bond can react with -OH, -NH or its active hydrogen-containing groups on the molecular chain of the base material to form a three-dimensional cross-linked network, which not only enhances the mechanical strength of the coating, but also significantly improves the compatibility.

[0040] At the same time, the introduction of the formyloxy structure gives the formyloxy polysilazane polymer flame retardant a unique chemical activity and flame retardant mechanism. During combustion, the formyloxy group decomposes under heat to generate carbon dioxide, which can effectively dilute oxygen and combustible molecules and prevent combustion; at the same time, the silicon and nitrogen elements inherent in the formyloxy polysilazane material can promote the formation of Si-O and NC composite carbon residues, covering the surface of the substrate with nano-scale particles, forming a microscopic fire extinguishing barrier, effectively isolating oxygen and preventing the spread of flames. The constructed carbon layer structure is stable and dense, which can significantly enhance the flame retardant properties.

[0041] In summary, the formyloxy polysilazane polymer flame retardant of the present application, on the one hand, can significantly improve the limiting oxygen index, combustion level, and residual carbon rate of the material and improve the flame retardancy by virtue of its innovative molecular structure and flame retardant mechanism; on the other hand, it can achieve a ceramic effect through chemical bonding to form an efficient flame retardant layer, which prevents dripping and flame spread, and has a profound impact on the fire safety and environmental sustainable development of polymer materials; in addition, it has a high reactivity and can react with active hydrogen-containing groups to improve compatibility with the base material, thereby improving the durability of the flame retardant effect and the comprehensive performance of the material.

[0042] In a preferred embodiment, R1 and R2 are independently selected from hydrogen, a C1-C5 straight chain or branched alkyl, a C2-C6 straight chain or branched alkenyl, a phenyl, and a C1-C6 secondary amine, and at least one of R1 and R2 is selected from hydrogen, and a C2-C6 straight chain or branched alkenyl, and / or; R3 is selected from hydrogen, a C1-C5 straight chain or branched alkyl, a C2-C6 straight chain or branched alkenyl, and a phenyl. By optimizing the components of R1, R2 and R3, the active sites can be further strengthened, the self-polymerization to form a dense carbon layer can be promoted, and the Si-N skeleton and the formyloxy group can be coordinated to more significantly improve the flame retardant performance and environmental friendliness, simplify the application process, and broaden the scope of use in the field of high-temperature structural flame retardant materials.

[0043] Based on similar reasons, in a preferred embodiment, R1 and R2 are independently selected from one of hydrogen, methyl, ethyl, vinyl, allyl, phenyl, and a secondary amine of C2 to C6, and at least one of R1 and R2 is selected from one of hydrogen, vinyl, and allyl, and / or; R3 is selected from one of hydrogen, and a straight or branched alkyl of C1 to C5.

[0044] The inventors further optimized the range of m and n. In a preferred embodiment, m and n are independently integers of 1 to 5. Under the above conditions, the reaction activity and carbonization efficiency of the flame retardant can be further synergistically enhanced to form a high-efficiency barrier layer, thereby significantly improving the flame retardant performance and environmental protection standards.

[0045] In a preferred embodiment, in the formyloxy polysilazane, R1 is hydrogen, R2 is methyl, R3 is hydrogen, m is 3, and n is 4, or, in the formyloxy polysilazane, R1 is methyl, R2 is vinyl, R3 is hydrogen, m is 2, and n is 2. In a preferred embodiment, at room temperature (20-30°C), the viscosity of the formyloxy polysilazane is 500-3000cps. Under the above conditions, each group cooperates with the Si-N skeleton and the formyloxy group to further improve the residual carbon rate, effectively solving the technical problems of fire resistance and environmental protection of polymer materials.

[0046] As described above, the polymer flame retardant formyloxy polysilazane of the present application has good flame retardancy. In a preferred embodiment, the residual carbon rate of the formyloxy polysilazane is 40-70%.

[0047] After a lot of experimental research, the inventors of the present application have optimized the preparation method of formyloxy polysilazane with a specific structure, so that it has excellent flame retardant properties.

[0048] In another typical embodiment of the present invention, a method for preparing formyloxy polysilazane is provided, comprising the following steps: introducing carbon dioxide into a closed container having a volume of 4.5 to 5.5 L, comprising a catalyst, an organic solvent and 1 kg of polysilazane, to carry out a first addition reaction, and controlling the initial pressure of carbon dioxide in the reaction system to be 0.6 to 1.6 MPa; then stopping the introduction of carbon dioxide, and carrying out a second addition reaction to obtain a product system comprising formyloxy polysilazane; the temperature of the first addition reaction is 30 to 45° C., and the time is 1 to 1.5 h; the temperature of the second addition reaction is 25 to 30° C., and the time is 1 to 2 h; wherein the polysilazane has a structure represented by the general formula (II),

[0049] ;

[0050] General formula (II);

[0051] wherein R1, R2 and R3 are as defined above, and p is an integer from 1 to 20.

[0052] In the presence of a catalyst and an organic solvent, the main raw material polysilazane and carbon dioxide undergo an addition reaction to obtain a product system including formyloxy polysilazane. The preparation method has a simple process, mild reaction conditions and low cost.

[0053] Typically but not limiting, the initial pressure of carbon dioxide is 0.6MPa, 1MPa, 1.2MPa, 1.3MPa, 1.6MPa or a range consisting of any two of them. Under the above conditions, CO2 and polysilazane have good reactivity and significant synergy, which can ensure the efficient introduction of formyloxy groups, help improve the limiting oxygen index and residual carbon rate of the material, and have a good flame retardant effect. If the ratio is too low, the formyloxy content may be reduced, thereby affecting the flame retardant properties and carbonization efficiency of the flame retardant; if the ratio is too high, too many formyloxy groups may be introduced, resulting in excessive changes in the molecular structure, reducing the stability of the flame retardant and the compatibility with the matrix material, thereby reducing the overall flame retardant effect and the comprehensive performance of the material.

[0054] Moreover, within the conditions of the first addition and the second addition, the catalyst activity and the molecular kinetic energy can be balanced, so that CO2 can be efficiently inserted into the polysilazane skeleton to form a formyloxy structure. At lower temperatures, the reaction rate may drop sharply, affecting the yield, while too high a temperature may cause the solution to be over-catalyzed and destroy the molecular structure. If the time is too long, the production cost will increase, and if the time is too short, the addition reaction may not be sufficient, resulting in a low product yield.

[0055] Excess or insufficient solvent may interfere with the reaction balance and affect the purity and application performance of the product. In a preferred embodiment, the weight ratio of polysilazane to organic solvent is 1: (1-10). Within the above range, the reaction process can be more accurately regulated, the effective contact between Si-N bonds and CO2 can be promoted, and the reaction efficiency can be improved.

[0056] In order to build a more stable reaction environment, promote the mild addition of CO2 and polysilazane, avoid proton competition, ensure the precise introduction of formyloxy, and synergistically enhance flame retardancy and material compatibility, in a preferred embodiment, the catalyst is a transition metal catalyst, preferably one or more of iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum in elemental form, salt form or complex compound form, and / or; the catalyst participates in the reaction process in the form of surface loading or homogeneous form. The use of the above catalyst can more effectively activate the interface reaction of CO2 and polysilazane, accelerate the embedding of formyloxy, and synergistically improve the flame retardant performance and synthesis efficiency.

[0057] In a preferred embodiment, the organic solvent is an aprotic solvent, preferably one or more of toluene, diethyl ether, tetrahydrofuran and n-hexane.

[0058] In a preferred embodiment, the preparation method further comprises the following steps: centrifuging, filtering and decompressing the product system in sequence to obtain formyloxy polysilazane. This step can further refine the product, remove residual solvents and by-products, and improve the purity and flame retardant performance of formyloxy polysilazane.

[0059] In the above-mentioned method for preparing formyloxy polysilazane, polysilazane is prepared by the following steps: subjecting chlorosilane to an ammonolysis reaction and a polymerization reaction to obtain polysilazane; the raw materials during the ammonolysis reaction also include ammonia or an organic amine, and / or; the temperature of the ammonolysis reaction and the polymerization reaction are both -40~50°C, preferably, the time of the ammonolysis reaction is 4~5h, and the time of the polymerization reaction is 3~8h. The above-mentioned method for preparing polysilazane is simple, the reaction conditions are mild, and the obtained polysilazane is resistant to high temperatures (>1500°C), which is more conducive to improving the flame retardant properties of formyloxy polysilazane.

[0060] In a preferred embodiment, the chlorosilane includes one or more of dichloromonosilane, vinylmethyldichlorosilane and trichlorosilane. The polysilazane prepared by using the above-mentioned chlorosilanes has a stable and efficient reaction system.

[0061] In another typical embodiment of the present invention, a flame retardant material is provided, wherein the formyloxy polysilazane and a base material are sequentially mixed, cured, and extruded to obtain a flame retardant material, wherein the base material comprises one or more of glass fiber, polymer masterbatch, and metal casting. This method can ensure that the flame retardant deeply interacts with the matrix to avoid agglomeration and precipitation, while maintaining or enhancing the mechanical properties of the material, providing a safer and more efficient flame retardant solution for different applications (such as high-end fields such as aerospace, electronics, and electrical).

[0062] In a preferred embodiment, the flame retardant material containing formyloxy polysilazane can release carbon dioxide when burned, and / or; in the flame retardant material, the weight percentage of formyloxy polysilazane is 0.1-20%, preferably 8-12%, typically but not limiting, in the flame retardant material, the weight percentage of formyloxy polysilazane is 0.1%, 1%, 5%, 8%, 10%, 12%, 15%, 20% or a range value composed of any two of them. The flame retardant material of the present application can release carbon dioxide when thermally decomposed, thereby significantly inhibiting the oxygen supply and reducing the combustion rate; during high-temperature combustion, the silanol bonds generated after the decomposition of the silicon nitrogen main chain are dehydrated, or the silanol directly reacts with the nitrogen silicon bond (the reaction formula is shown below), producing a ceramic effect, which is deposited on the surface of the material, and can play a role in heat insulation and oxygen isolation, thereby further improving the flame retardancy of the material, which is of great value in solving the fire safety problem of polymer materials under extreme conditions.

[0063]

[0064]

[0065] In a preferred embodiment, the limiting oxygen index of the flame retardant material is 27-43%, the self-extinguishing time after leaving the flame is ≤3s, and the flame retardant grade UL-94≥V2.

[0066] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0067] Example 1

[0068] Trichlorosilane prepolymer (manufacturer: Zhejiang Kaihua Synthetic Materials Co., Ltd.) and dichloromonosilane prepolymer (manufacturer: Zhejiang Kaihua Synthetic Materials Co., Ltd.) were added at a weight ratio of 0.5:1, and then stirred evenly. Under the action of the catalyst diallylamine, ammonia was introduced into the above chlorosilane mixture at -20°C for 4 hours of aminolysis reaction, and then the polymerization reaction was continued at -20°C for 5 hours with stirring. The above reactants were filtered, and then low molecular volatiles were extracted at a pressure of -0.098MPa to obtain polysilazane with a yield of 71%. The infrared absorption curve of polysilazane is shown in Figure 1 , among which, FT-IR(n): near 3379cm -1 (-SiN-H), near 2960 cm -1 (-CH3), near 2120 cm -1 (-Si-H), near 1253 cm -1 (-Si-CH3), near 879 cm -1 (-Si-N). The structure of polysilazane is as follows:

[0069] .

[0070] The catalyst is selected as palladium catalyst, the organic solvent is n-hexane, and the weight ratio of polysilazane to organic solvent is 1:5. In a closed reactor with a volume of 5L equipped with an air inlet, a thermometer, a condenser and a reflux tube, the above-mentioned pre-measured polysilazane is added, and carbon dioxide is introduced into 1kg of polysilazane (carbon dioxide can replace air). The initial pressure of the reaction system is controlled to be 0.6~1MPa. The reaction is first carried out at 40°C for 1h in the presence of an organic solvent, and then the introduction of carbon dioxide is stopped, and it is continued at 29°C for 2h to obtain a product system including formyloxypolysilazane. After the reaction is completed, the solid product is removed by centrifugation, and then filtered, followed by decompression (first at 30°C, -0.085MPa for 2h; then at 50°C, -0.098MPa for 1h) to remove the solvent from the filtrate. Formyloxypolysilazane is obtained. The structure of formyloxypolysilazane is as follows. The infrared absorption curve of formyloxypolysilazane is shown in Figure 2 , where FT-IR(n): near 3350 cm -1 (-SiN-H), near 2960 cm -1 (-CH3), near 2200 cm -1 (-Si-H), near 1653 cm -1 (-C=O), near 1247 cm -1 (-Si-CH3), near 886cm -1 At (-Si-N-).

[0071] .

[0072] The raw materials of the polyurethane (polyol, diisocyanate and chain extender, wherein the isocyanate index R value, i.e., the molar ratio of the isocyanate group to the hydroxyl group is set to 1.0) are mixed evenly and injected into the feeding section of a twin-screw extruder to obtain a mixture. The formyloxy polysilazane (the weight percentage of the formyloxy polysilazane in the flame retardant material is controlled to be 8%) is injected into the end of the twin-screw extruder through an injection port by a gear pump. After mixing, reaction and extrusion molding, a modified polyurethane elastomer material (i.e., the flame retardant material of the present application) is obtained.

[0073] Example 2

[0074] The only difference from Example 1 is:

[0075] The catalyst is a palladium catalyst and the organic solvent is tetrahydrofuran. In a closed reactor with a volume of 5L, polysilazane is added, carbon dioxide is introduced into 1kg of polysilazane, and the initial pressure of the reaction system is controlled to be 0.6~1.0MPa. The reaction is first carried out at 40°C for 1.5h, and then the introduction of carbon dioxide is stopped, and the reaction is continued at 30°C for 1.5h to obtain a product system including formyloxy polysilazane. After the reaction is completed, the solid product is removed by centrifugation, and then filtered, followed by decompression (first at 30°C, -0.085MPa for 2h; then at 50°C, -0.098MPa for 1h) to remove the solvent from the filtrate. Formyloxy polysilazane is obtained.

[0076] The preparation process of the flame retardant material is the same as that of Example 1.

[0077] Example 3

[0078] The only difference from Example 1 is that the catalyst is a palladium catalyst and the organic solvent is n-hexane.

[0079] In a closed reactor with a volume of 5L, 1kg of polysilazane is added, carbon dioxide is introduced into the polysilazane, the initial pressure of the reaction system is controlled to be 1.0-1.2MPa, and the reaction is first carried out at 40°C for 3h in the presence of an organic solvent, and then the introduction of carbon dioxide is stopped, and the reaction is continued at 30°C for 1.5h to obtain a product system including formyloxy polysilazane. After the reaction is completed, the solid product is removed by centrifugation, and then filtered, followed by decompression (first at 30°C, -0.085MPa for 2h; then at 50°C, -0.098MPa for 1h) to remove the solvent from the filtrate to obtain formyloxy polysilazane.

[0080] The preparation process of the flame retardant material is the same as that of Example 1.

[0081] Example 4

[0082] The only difference from Example 1 is:

[0083] In a closed reactor with a volume of 5L, 1kg of polysilazane is added, carbon dioxide is introduced into the polysilazane, the initial pressure of the reaction system is controlled to be 1.3-1.6MPa, and the reaction is first carried out at 40°C for 3h in the presence of an organic solvent, and then the introduction of carbon dioxide is stopped and the reaction is continued at 30°C for 1.5h to obtain a product system including formyloxy polysilazane. After the reaction is completed, the solid product is removed by centrifugation, and then filtered, followed by decompression (first at 30°C and -0.085MPa for 2h; then at 50°C and -0.098MPa for 1h) to remove the solvent from the filtrate to obtain formyloxy polysilazane.

[0084] Example 5

[0085] The only difference from Example 1 is that the added amount of formyloxy polysilazane is 10 wt %.

[0086] Example 6

[0087] The only difference from Example 1 is that the added amount of formyloxy polysilazane is 12 wt %.

[0088] Example 7

[0089] The only difference from Example 1 is that trichlorosilane prepolymer and vinylmethyldichlorosilane prepolymer are added at a weight ratio of 0.5:1 to obtain polysilazane, the structure of which is as follows. The infrared absorption curve of polysilazane is shown in Figure 3 , FT-IR(n): near 3379 cm -1 (-SiN-H), near 3045 cm -1 At (-C=CH2), near 2954 cm -1 At (-CH3), near 1253 cm -1 (-Si-CH3), near 905 cm -1 At (-Si-N-).

[0090] .

[0091] Adjust the raw material conditions to obtain formyloxy polysilazane, the structure of which is as follows. The infrared absorption curve of formyloxy polysilazane is shown in Figure 4 FT-IR(n): Near 3350 cm -1 (-NH), near 3045 cm -1 at (-C=CH2), near 2960 cm -1 (-CH3), near 1683 cm -1 (-C=O), near 1247 cm -1(-Si-CH3), near 911 cm -1 At (-Si-N-).

[0092] .

[0093] Comparative Example 1

[0094] See CN 116813915 A Example 1.

[0095] Comparative Example 2

[0096] The difference from Example 1 is:

[0097] No flame retardants were added to the polyurethane for improvement.

[0098] Comparative Example 3

[0099] The difference from Comparative Example 2 is:

[0100] The flame retardant formyloxy polysilazane of the present application is not added to the polyurethane, but traditional flame retardants (melamine urate and polyphosphate amine) are added. Specifically, in terms of weight percentage, melamine urate accounts for 15.36% and polyphosphate amine accounts for 7.64% of the raw materials of the flame retardant material. The flame retardant is measured at the end of the extruder through a loss-in-weight scale, and then added to the polyurethane melt through a twin-screw feeder installed on the side of the main machine. The flame retardant addition accounts for 23% of the total mass of the flame retardant material.

[0101] The formyloxy polysilazane and flame retardant materials prepared in the above examples and comparative examples were tested, and the results are shown in Table 1.

[0102] Test method:

[0103] Limiting oxygen index: Tested in accordance with GB / T 2406.2.

[0104] Carbon residue rate: Refer to GB / T 268 for testing and calculation data.

[0105] Mechanical property test: The test was conducted with reference to GB / T528-2009. Specifically, the tensile rate was 500 mm / min.

[0106] Flame retardant performance test: The test was conducted with reference to ANSI UL-94. Specifically, the sample was burned vertically and the sample thickness was 1.6 mm.

[0107] Yield: Calculated according to the following formula: Yield = (actual yield / theoretical yield) × 100%.

[0108] Table 1

[0109]

[0110] As shown in Table 1, as the carbon dioxide pressure increases during the reaction, the polar formyloxy groups introduced into the main chain increase, and the product viscosity increases from 2040MPa·s to 2970MPa·s. The carbon dioxide released by high-temperature decomposition increases accordingly, and the char residue rate on burning decreases from 68% to 41%. If polar tetrahydrofuran is used as a solvent, the char residue rate is reduced to 64%, which is slightly lower than that of Example 1 using a non-polar solvent. The product viscosity of Example 7 with a side chain double bond is lower than that of Example 1, but the char residue rate is lower. The viscosity of Comparative Example 1, which introduces the reactive flame retardant DOPO, is significantly higher than that of the examples.

[0111] Compared with Comparative Example 2, the formyloxy polysilazane polymer flame retardant in the embodiment of the present invention has extremely high flame retardant properties and anti-dripping properties. When the addition amount of formyloxy polysilazane is more than 8%, the limiting oxygen index of the flame retardant material can reach more than 32. The formyloxy polysilazane having the structure in Example 1, as a flame retardant, has high mechanical properties and flame retardant properties. At different addition ratios, it has extremely high anti-dripping properties. The residual carbon rate is used as an evaluation of the ceramicization level. It can be seen that the higher the ignition residual carbon rate of methoxy polysilazane, the corresponding anti-dripping performance is improved.

[0112] Compared with Comparative Example 3, in the embodiment of the present application, as the amount of formyloxy polynitrogen silane added increases to more than 12%, the limiting oxygen index of the flame retardant material is increased to 42.2, the flame retardant performance reaches UL94 V0 level, and it has good anti-dripping and self-extinguishing properties, and the mechanical properties are better than those of the material with the addition of traditional nitrogen-phosphorus composite flame retardant.

[0113] It can be seen that the polymer flame retardant of the present invention can not only significantly improve the flame retardant performance, but also construct a durable coating with both electrochemical protection and physical shielding through chemical bonding, effectively resisting flame invasion. It uses CO2 as a raw material, which can not only innovate the preparation path of flame retardants and realize the active control of carbon emissions, but also can release CO2 autonomously under combustion conditions, form a non-flammable dilution barrier, interrupt the combustion chain reaction, and assist with heat dissipation and cooling mechanism to comprehensively suppress the spread of fire. Moreover, the flame retardant does not require complex pretreatment, and can be directly coated to form a stable and efficient flame retardant layer, simplify the production process, control costs, and ensure strong bonding with the substrate at the same time, maintain flame retardant properties for a long time, and have a profound impact on the fire safety and environmental sustainable development of polymer materials.

[0114] In addition, it can be seen that when the process parameters are within the preferred range of the present invention, the flame retardant effect of the flame retardant is better.

[0115] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A formyloxy polysilazane, characterized in that: The formyloxy polysilazane has a structure shown in general formula (I): ； General formula (I); wherein R1 and R2 are independently selected from one of hydrogen, a C1-C10 straight chain or branched chain alkyl group, a C2-C10 straight chain or branched chain alkenyl group, a C6-C20 substituted or unsubstituted aryl group, and a C1-C10 secondary amine group, and at least one of R1 and R2 is selected from one of hydrogen and a C2-C10 straight chain or branched chain alkenyl group; R3 is selected from one of hydrogen, C1-C10 straight chain or branched chain alkyl, C2-C10 straight chain or branched chain alkenyl, and C6-C20 substituted or unsubstituted aryl; m and n are each independently an integer of 1 to 10, and n / (m+n)=0.1~0.

7.

2. The formyloxypolysilazane according to claim 1, characterized in that R1 and R2 are independently selected from one of hydrogen, C1-C5 straight chain or branched chain alkyl, C2-C6 straight chain or branched chain alkenyl, phenyl, and C1-C6 secondary amine, and at least one of R1 and R2 is selected from one of hydrogen and C2-C6 straight chain or branched chain alkenyl, and / or; R3 is selected from one of hydrogen, C1-C5 straight chain or branched chain alkyl, C2-C6 straight chain or branched chain alkenyl, and phenyl.

3. The formyloxypolysilazane according to claim 1 or 2, characterized in that R1 and R2 are independently selected from one of hydrogen, methyl, ethyl, vinyl, allyl, phenyl, and a C2-C6 secondary amine group, and at least one of R1 and R2 is selected from one of hydrogen, vinyl, and allyl, and / or; R3 is selected from hydrogen, and a C1-C5 straight or branched alkyl group.

4. The formyloxypolysilazane according to claim 1 or 2, characterized in that m and n are each independently an integer of 1 to 5.

5. The formyloxypolysilazane according to claim 1 or 2, characterized in that In the formyloxy polysilazane, R1 is hydrogen, R2 is methyl, R3 is hydrogen, m is 3, and n is 4. Alternatively, in the formyloxy polysilazane, R1 is methyl, R2 is vinyl, R3 is hydrogen, m is 2, and n is 2.

6. The formyloxypolysilazane according to claim 1 or 2, characterized in that The viscosity of the formyloxy polysilazane is 500-3000 cps, and / or; The residual carbon rate of the formyloxy polysilazane is 40-70%.

7. The method for preparing the formyloxypolysilazane according to any one of claims 1 to 6, characterized in that: The following steps are involved: In a sealed container with a volume of 4.5-5.5 L, including a catalyst, an organic solvent and 1 kg of polysilazane, carbon dioxide is introduced to carry out a first addition reaction, and the initial pressure of the carbon dioxide in the reaction system is controlled to be 0.6-1.6 MPa; Then, the introduction of the carbon dioxide is stopped, and a second addition reaction is performed to obtain a product system including the formyloxy polysilazane; The temperature of the first addition reaction is 30-45°C, and the time is 1-1.5 hours; the temperature of the second addition reaction is 25-30°C, and the time is 1-2 hours; Wherein, the polysilazane has a structure represented by general formula (II), ； General formula (II); wherein R1, R2 and R3 are as defined in any one of claims 1 to 6, and p is an integer from 1 to 20.

8. The method for preparing formyloxypolysilazane according to claim 7, characterized in that: The weight ratio of the polysilazane to the organic solvent is 1:(1-10).

9. The method for preparing formyloxypolysilazane according to claim 7, characterized in that: The catalyst is a transition metal catalyst, and / or; the catalyst participates in the reaction process in a surface-supported form or a homogeneous form, and / or; The organic solvent is an aprotic solvent.

10. The method for preparing formyloxypolysilazane according to claim 7, characterized in that: The preparation method also includes the following steps: The product system is sequentially centrifuged, filtered, and decompressed to obtain the formyloxy polysilazane.

11. A flame retardant material, characterized in that: The flame retardant material is obtained by mixing, curing and extruding the formyloxy polysilazane according to any one of claims 1 to 6 with a base material, wherein the base material comprises one or more of glass fiber, polymer masterbatch and metal casting.

12. The flame retardant material according to claim 11, characterized in that: The flame retardant material is capable of releasing carbon dioxide when burned.

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