Flame-retardant polyol as well as preparation method and application thereof

Abstract

The invention discloses flame-retardant polyol as well as a preparation method and application thereof, and belongs to the technical field of preparation of high polymer materials. The preparation method of the flame-retardant polyol comprises the following steps: adding a solvent and 3-aminopropyltrimethoxysilane into epoxidized soybean oil, heating, and reacting to obtain modified epoxidized soybean oil; and then adding 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, carrying out a heating reaction, and after the reaction is finished, carrying out cooling to obtain the product. The high-hydroxyl-value flame retardant containing Si, N and P elements and prepared from two products mixed according to a specific proportion is synthesized by adopting a molecular design principle, a multi-layer continuous efficient protection barrier in which gas-phase flame retardance and condensed-phase flame retardance are mutually promoted can be constructed, reactive flame-retardant polyurethane synthesized from the flame-retardant polyol has an excellent flame-retardant effect, and the flame-retardant polyol has a good flame-retardant effect. The use of halogen is avoided, and the defect that the performance of an additive flame retardant is reduced due to migration of the flame retardant is overcome.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer material preparation, in particular to a flame-retardant polyol and a preparation method and application thereof. BACKGROUND

[0002] Polyurethane material is an organic polymer material, which is extremely flammable, with a limiting oxygen index (LOI) of only 18. When burning, it releases a large amount of heat, is prone to dripping, and produces a large amount of toxic gases such as HCN, CO, NH3 and smoke, which poses a significant threat to people's lives and property. Therefore, it is of great significance to improve the flame retardancy of polyurethane materials.

[0003] The flame retardants currently used in polyurethane can be divided into reaction-type flame retardants and additive-type flame retardants. The additive-type flame retardants mainly include aluminum hydroxide, nitrogen-phosphorus intumescent flame retardants, and double-layer metal hydroxide flame retardants. The compatibility of these flame retardants with the matrix is poor, which can cause performance degradation, and the addition amount is large, which can cause weight increase. Therefore, some researchers use the synergistic effect between nitrogen-phosphorus intumescent flame retardants and double-layer metal hydroxide flame retardants to add both of them in the polyurethane matrix, but this can cause the two types of flame retardants to not mix uniformly at the micro level, which greatly reduces the synergistic effect between the flame retardants. The mechanical properties of the existing flame-retardant polyols after being added cannot meet the requirements, or the prepared polyurethane materials still have problems such as dripping after burning. Therefore, it is urgent to develop new flame-retardant polyols to solve the above problems.

[0004] Reaction-type flame retardants are flame-retardant elements or groups that are introduced into the polyurethane molecular structure, so that the matrix itself contains flame-retardant components. Compared with additive-type flame retardants, reaction-type flame retardants have a smaller usage amount, better compatibility with the matrix, and less impact on the performance of polyurethane materials. More importantly, corresponding functional groups or branches can be introduced as needed to meet special performance requirements. The reaction-type flame-retardant technology of polyurethane is the future development direction.

[0005] Nitrogen, phosphorus, and silicon elements are commonly used additives in halogen-free flame retardants. They can decompose to produce inert gases at high temperatures, forming a flame-retardant layer to prevent fire spread. In addition, these elements can form a dense oxide layer on the surface of the material, preventing oxygen from further participating in the reaction and improving the fire resistance of the material. Compared with traditional halogen flame retardants, nitrogen, phosphorus, and silicon elements have better environmental performance. Due to the presence of halogen elements, which can cause smoke toxicity and the production of harmful gases, the use of halogen flame-retardant materials has been explicitly prohibited in some countries and regions. Nitrogen, phosphorus, and silicon elements do not contain halogen elements and have better environmental performance, making them more suitable for the current social demand for increasing environmental awareness.

[0006] However, existing single P-based, N-based, or Si-based flame retardants have significant limitations. For example, P-based retardants are hygroscopic and produce a large amount of smoke; N-based retardants have low efficiency when used alone; and Si-based retardants have weak flame retardancy. Therefore, some researchers have compounded several existing NP or P-Si retardants. While this has solved some problems, issues remain, such as insufficient synergistic efficiency, poor char quality, and limited high-temperature protection. In particular, simple addition can cause a rapid decline in the mechanical properties of the original matrix resin material. Therefore, there is an urgent need to develop new P, N, and Si-based flame retardants to address these issues. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a flame-retardant polyol, its preparation method, and its applications. This invention utilizes the principles of molecular design to synthesize a phosphorus-, nitrogen-, and silicon-containing flame-retardant polyol. This flame-retardant polyol is then used to synthesize a reactive flame-retardant polyurethane, introducing flame-retardant elements into the polyurethane material. This results in a polyurethane with excellent flame-retardant properties and superior material performance, avoiding the use of halogens and overcoming the performance degradation caused by the migration of flame retardants in additive flame retardants.

[0008] The technical solution of the present invention is as follows: The first aspect of this invention protects a method for preparing a flame-retardant polyol, comprising the following steps: S1: Add solvent and 3-aminopropyltrimethoxysilane to epoxidized soybean oil, and react after heating to obtain modified epoxidized soybean oil; S2: Add 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to the modified epoxidized soybean oil obtained in step S1, stir evenly, heat up to react, and after the reaction is completed, cool down to obtain flame-retardant polyol.

[0009] Preferably, in S1, the epoxy value of the epoxidized soybean oil is 3.0% to 6.8%, more preferably 5.0% to 6.5%.

[0010] Preferably, in S1, the solvent includes at least one selected from toluene, xylene, ethyl acetate, and n-hexane; The mass ratio of the epoxidized soybean oil to the solvent is 1:1~10; The mass ratio of the epoxidized soybean oil to the 3-aminopropyltrimethoxysilane is 10~2:1, preferably 6~3:1.

[0011] Preferably, in S1, the reaction temperature is 40~120℃, more preferably 60~80℃; and / or, The reaction time is 4 to 48 hours, preferably 8 to 24 hours.

[0012] Preferably, in S2, the mass ratio of the modified epoxidized soybean oil to the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 10~0.2:1, more preferably 6~4:1; The 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is added after heating the modified epoxidized soybean oil obtained in step S1 to 80~120℃.

[0013] Preferably, in S2, the reaction temperature is 80~180℃, more preferably 120~160℃; and / or, The reaction time is 4 to 24 hours, preferably 6 to 12 hours.

[0014] The second aspect of this invention protects a flame-retardant polyol prepared by the preparation method described in the first aspect above, wherein the flame-retardant polyol has a hydroxyl value of 170~195 mg KOH / g.

[0015] The third aspect of this invention protects a method for preparing a polyurethane material, comprising the following steps: (1) Add flame-retardant polyol to oil polyol, disperse and heat to react. After the reaction is completed, cool to room temperature to obtain the initial product; (2) The initial product is stirred and dispersed with isocyanate, cast and cured to obtain polyurethane material.

[0016] Preferably, in step (1), the mass ratio of the flame-retardant polyol to the oil polyol is 3~10:10; Preferably, the oil polyol includes at least one of castor oil, modified soybean oil, and palm oil; The heating reaction is carried out at a temperature of 75-85°C, and / or, The heating reaction time is 2-4 hours; In step (2), the isocyanate includes at least one of polymethylene polyphenyl isocyanate, or diphenylmethane diisocyanate, or toluene diisocyanate; The mass ratio of the isocyanate to the flame-retardant polyol in step (1) is 4~15:5; The curing process involves curing at a first temperature for time t1, then raising the temperature to a second temperature and curing for time t2. The first temperature is 40~80℃; and / or, t1 is 10~14h; The second temperature is 75~85℃, and / or the t2 is 1~3h.

[0017] A fourth aspect of this invention protects a polyurethane material prepared by the preparation method described in the third aspect above.

[0018] The beneficial technical effects of this invention are as follows: (1) The present invention reacts epoxidized soybean oil (ESO) with 3-aminopropyltrimethoxysilane and obtains two long-chain products containing Si and N elements by controlling the reaction conditions; further, by introducing phosphorus-containing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, a flame retardant containing Si, N and P elements and mixed in a specific ratio is obtained.

[0019] (2) The flame retardant prepared in this invention combines the synergistic flame retardant effects of phosphorus-nitrogen-silicon. Its core lies in the fact that the non-flammable gases (NH3, N2, H2O, CO2, etc.) generated by the thermal decomposition of the nitrogen-containing component synergistically react with the catalytic dehydration and char formation of the phosphorus-containing component, forming an expanded, porous initial char layer within the matrix. Simultaneously, the silicon-containing component migrates to the surface and interior of the char layer at high temperatures, significantly enhancing the density, strength, thermal stability, and oxidation resistance of the char layer by forming a Si-OC crosslinking network and a silicate glass layer, thereby constructing a multi-layered, continuous, and highly efficient protective barrier where gas-phase flame retardancy and condensed-phase flame retardancy mutually promote each other. Compared with a single NP system or P-Si system, the limiting oxygen index (LOI) of the flame retardant material of this invention is increased by more than 15% at the same addition amount. Compared with the existing NP-Si system, this invention has advantages such as high synergistic efficiency, excellent char layer quality, and strong high-temperature protection capability. Furthermore, this flame retardant has a high hydroxyl content, participating in the polyurethane curing reaction, solving the migration problem of traditional flame retardants. Therefore, the nitrogen-containing component... phosphorus Silicon-based flame retardants offer insights for the development of new flame-retardant polyols.

[0020] (3) The flame retardant prepared in this invention belongs to the same category of natural oil polyols as castor oil, and has good compatibility. After reaction with isocyanate and chain extension, it can effectively improve the comprehensive properties of polymer materials such as compatibility, heat resistance, and toughness. Therefore, the polyurethane cured product prepared in this invention has good thermal stability, weather resistance, and impact toughness, and is suitable for the encapsulation and bonding of electronic devices, with broad prospects for industrial application. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the synthetic route for the modified epoxidized soybean oil (ESO-Si, product 1 + product 2) of this invention; and a schematic diagram of the synthetic route for the flame-retardant polyol (ESO-Si-DOPO, product 3 + product 4).

[0022] Figure 2 The images shown are scanning electron microscope (SEM) images of the fracture surfaces of polyurethane samples prepared in Example 1 and Comparative Example 1 of this invention after vertical combustion, both magnified 1000 times.

[0023] In the figure: A is Comparative Example 1; B is Example 1.

[0024] Figure 3 The image shows the infrared spectrum of the raw materials and products used in this invention.

[0025] In the diagram: A represents epoxidized soybean oil ESO; B represents modified epoxidized soybean oil ESO-Si; and C represents ESO-Si-DOPO.

[0026] Figure 4 This is the 1H NMR spectrum of the epoxidized soybean oil (ESO) used in this invention.

[0027] Figure 5 The image shows the 1H NMR spectrum of the modified epoxidized soybean oil ESO-Si prepared in Example 1 of this invention.

[0028] Figure 6 The image shows the hydrogen NMR spectrum of ESO-Si-DOPO prepared in Example 1 of this invention. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the embodiments.

[0030] Given the shortcomings of existing single or two-component P, N, and Si flame retardants, those skilled in the art have begun to study three-component flame retardants. However, these flame retardants have diverse structures and various problems. There is an urgent need to provide new P, N, and Si composite flame retardants with superior performance. Therefore, this invention proposes a flame-retardant polyol, its preparation method, and its application to solve the above problems and provide a new three-element composite flame retardant.

[0031] The first aspect of this invention provides a method for preparing a flame-retardant polyol, comprising the following steps: S1: Add solvent and 3-aminopropyltrimethoxysilane APTMS to epoxidized soybean oil, and react after heating to obtain modified epoxidized soybean oil.

[0032] S2: Add 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) to the modified epoxidized soybean oil obtained in step S1, stir evenly, heat up to react, and after the reaction is completed, cool down to obtain flame-retardant polyol.

[0033] It is understandable that, such as Figure 1 As shown, this invention reacts epoxidized soybean oil (ESO) with 3-aminopropyltrimethoxysilane and, by controlling the reaction conditions, obtains two long-chain products containing Si and N elements, namely product 1 and product 2; further, by introducing phosphorus-containing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, flame retardants containing Si, N, and P elements in a specific ratio are obtained, namely product 3 and product 4. Figure 1 In this context, the R group includes the following structures: (5); The structure of product 1 is as follows: (1); The structure of product 2 is as follows: (2); The structure of product 3 is as follows: (3); The structure of product 4 is as follows: (4); The structure of R is the same as the structure described above (5).

[0034] It is understood that the flame retardant of this invention constructs a multi-layered, continuous protective system that strengthens over time, extending from the material's interior to its surface, through a process of P-catalytic char formation + N-gas expansion + Si-ceramization reinforcement. Furthermore, it possesses a high hydroxyl value, allowing it to participate in the polyurethane curing reaction, thus solving the migration problem of traditional flame retardants and providing insights for the development of new flame-retardant polyols.

[0035] In some implementations, the addition of solvent to epoxidized soybean oil requires purging the container containing the epoxidized soybean oil with nitrogen gas to remove trace amounts of oxygen and water before adding the solvent and APTMS under nitrogen inert gas protection. Failure to remove oxygen and water will lead to increased side reactions.

[0036] In some embodiments, in S1, the epoxy value of the epoxidized soybean oil is 3.0% to 6.8%, preferably 5.0% to 6.5%.

[0037] It is understandable that if the epoxy value of the epoxidized soybean oil used in this invention is too high, it will result in excessive crosslinking density during curing; if it is too low, it will result in insufficient crosslinking density during curing.

[0038] In some embodiments, in S1, the solvent includes at least one of toluene, xylene, ethyl acetate, and n-hexane.

[0039] In some embodiments, the mass ratio of the epoxidized soybean oil to the solvent is 1:1 to 10.

[0040] In some embodiments, the mass ratio of the epoxidized soybean oil to the 3-aminopropyltrimethoxysilane is 10 to 2:1, preferably 6 to 3:1.

[0041] In some embodiments, in S1, the reaction temperature is 40~120°C, preferably 60~80°C.

[0042] In some embodiments, the reaction time is 4 to 48 hours, preferably 8 to 24 hours.

[0043] The modified epoxidized soybean oil obtained in step S1 of this invention comprises product 1 and product 2, the structures of which are as follows: Figure 1 As shown in the figure. Analysis of the products using 1H NMR and infrared spectroscopy revealed that the molar ratio of product 1 to product 2 was 2:1.

[0044] In some embodiments, in S2, the mass ratio of the modified epoxidized soybean oil to the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 10~0.2:1, preferably 6~4:1.

[0045] In some embodiments, the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is added after heating the modified epoxidized soybean oil obtained in step S1 to 80~120°C.

[0046] In some embodiments, in S2, the temperature of the reaction is 80~180°C, preferably 120~160°C.

[0047] In some embodiments, the heat preservation reaction time is 4 to 24 hours, preferably 6 to 12 hours.

[0048] Understandably, if the reaction temperature is too high, it will cause a large number of side reactions, while if the temperature is too low, the DOPO reaction will be incomplete.

[0049] The second aspect of the present invention provides a flame-retardant polyol prepared by the preparation method described in the first aspect above, wherein the flame-retardant polyol has a hydroxyl value of 170~195 mg KOH / g.

[0050] Detection of the products by 1H NMR and infrared spectroscopy revealed that the flame-retardant polyol of this invention comprises products 3 and 4 in a molar ratio of 2:1, and the structures of products 3 and 4 are as follows. Figure 1 As shown, they all contain N, P, and Si elements and have high hydroxyl values.

[0051] It is understood that this invention, through optimization of raw materials and preparation processes, yields a flame-retardant polyol containing N, P, and Si elements simultaneously, with a high hydroxyl value of 170-195 mg KOH / g. Too low a hydroxyl value will result in incomplete curing; too high a hydroxyl value will lead to excessively high crosslinking density and reduced polyurethane elasticity. After the S2 reaction is completed and the mixture cools to room temperature, the process further includes adding water, stirring and washing, allowing it to settle and separate into layers, removing the water layer, and rotary evaporating the organic layer to remove the solvent.

[0052] A third aspect of this invention provides a method for preparing a polyurethane material, comprising the following steps: (1) Add flame-retardant polyol to oil polyol, disperse and heat to react. After the reaction is complete, cool to room temperature to obtain the initial product.

[0053] (2) The initial product is stirred and dispersed with isocyanate, cast and cured to obtain polyurethane material.

[0054] In some embodiments, in step (1), the mass ratio of the flame-retardant polyol to the oil polyol is 3~10:10.

[0055] In some embodiments, the oil polyol includes at least one of castor oil, modified soybean oil, and palm oil.

[0056] In some embodiments, the temperature of the heating reaction is 75~85°C, and / or the heating reaction time is 2~4 hours.

[0057] In some embodiments, in step (2), the isocyanate includes at least one of polymethylene polyphenyl isocyanate (PAPI), diphenylmethane diisocyanate (MDI), and toluene diisocyanate (TDI).

[0058] In some embodiments, the mass ratio of the isocyanate to the flame-retardant polyol in step (1) is 5 to 15:5.

[0059] In some implementations, in step (2), the curing is performed by curing at a first temperature for time t1, followed by heating to a second temperature and curing for time t2.

[0060] In some embodiments, the first temperature is 40~80°C; and / or, t1 is 10~14h.

[0061] In some embodiments, the second temperature is 75~85°C, and / or, t2 is 1~3h.

[0062] A fourth aspect of this invention provides a polyurethane material prepared by the method described in the third aspect above. Through improvements to flame-retardant polyols and optimization of the polyurethane preparation process, the resulting polyurethane material exhibits excellent thermal stability, weather resistance, and impact toughness, making it suitable for the encapsulation and bonding of electronic devices, and showing broad prospects for industrial applications.

[0063] The castor oil used in the preparation of the polyurethane material in this invention has a hydroxyl equivalent of 350 and an isocyanate equivalent of 145 for PAPI.

[0064] The following are specific implementation examples.

[0065] Example 1 A flame-retardant polyol is prepared by the following steps: (1) Preparation of modified epoxidized soybean oil (ESO-Si) 100g of epoxidized soybean oil (epoxidation value: 6.3%) was placed in a three-necked round-bottom flask equipped with a condenser and thermometer. Nitrogen gas was purged to remove any trace amounts of oxygen and water. Under nitrogen inert gas protection, 200g of toluene and 20g of APTMS were added. The mixture was heated to 60°C and stirred for 24 hours to obtain the first step product. Figure 3 , Figures 4-5 The epoxidized soybean oil used in this invention is presented, along with the infrared spectrum and 1H NMR spectrum of the modified epoxidized soybean oil prepared in this embodiment. The 1H NMR spectrum and infrared spectrum show that the obtained products include product 1 and product 2, with a molar ratio of product 1 to product 2 of 2:1. The structures of product 1 and product 2 are as follows... Figure 1 As shown.

[0066] (2) The modified epoxidized soybean oil (ESO-Si, the first step product) was added to a three-necked flask, protected with nitrogen, and then heated to 100°C. 20g of DOPO was gradually added to the reaction mixture and stirred for half an hour to ensure that the molten DOPO was completely and uniformly dispersed in the modified epoxidized soybean oil. The mixture was then heated to 160°C for further reaction and kept at this temperature for 12 hours. The temperature was then lowered to approximately 25°C, 100g of water was added, and the mixture was stirred and washed. After standing and separating into layers, the water layer was removed, and the organic layer was evaporated by rotary evaporation to remove the solvent. Finally, a transparent, pale yellow product, i.e., a flame-retardant polyol, was obtained, designated ESO-Si-DOPO-1. Its hydroxyl value was 185 mg KOH / g. The hydroxyl value of this invention was determined using the national standard GB12008.3-89 method. Figure 3 , Figure 6 The infrared spectrum and 1H NMR spectrum of the flame-retardant polyol prepared in this embodiment are given. It can be seen that the obtained flame-retardant polyol includes product 3 and product 4, with a molar ratio of 2:1, and the structure is as follows. Figure 1 As shown.

[0067] A polyurethane material, the preparation method of which includes the following steps: (1) Weigh 10g of castor oil using an electronic balance and add it to a three-necked flask; (2) After drying 5g of the ESO-Si-DOPO-1 prepared above, add the castor oil reaction solution from step (1) above, disperse it evenly, heat it to 80°C, react for 3 hours, and then cool it to room temperature to obtain the initial product.

[0068] (3) Weigh 7.25g of PAPI and the initial product of (2) above into a beaker using an electronic balance, stir evenly in a constant temperature water bath at 30℃ for 1 / 2 hour until evenly dispersed; pour into a mold for casting, cure at 60℃ for 12 hours, and cure at 80℃ for 2 hours to obtain a standard sample of polyurethane material.

[0069] Example 2 A flame-retardant polyol is prepared by the following steps: (1) Preparation of modified epoxidized soybean oil (ESO-Si) 100g of epoxidized soybean oil (epoxidation value: 5.3%) was placed in a three-necked round-bottom flask equipped with a condenser and thermometer. Nitrogen gas was purged to remove any trace amounts of oxygen and water. Under nitrogen inert gas protection, 200g of toluene and 20g of APTMS were added. The mixture was heated to 60°C and stirred for 24 hours to obtain the first-step product. Analysis of the first-step product prepared in this example by 1H NMR spectroscopy and infrared spectroscopy revealed that the obtained product includes… Figure 1 The product 1 and product 2 are shown, and the molar ratio of product 1 to product 2 is 2:1.

[0070] (2) The modified epoxidized soybean oil (ESO-Si, the first step product) was added to a three-necked flask, protected with nitrogen, and then heated to 100°C. 20g of DOPO was gradually added to the reaction mixture and stirred for half an hour to ensure that the molten DOPO was completely and uniformly dispersed in the modified epoxidized soybean oil. The mixture was then heated to 160°C for further reaction and kept at that temperature for 12 hours. The temperature was then lowered to approximately 25°C, 100g of water was added, and the mixture was stirred and washed. After standing and separating into layers, the water layer was removed, and the organic layer was evaporated by rotary evaporation to remove the solvent. Finally, a transparent, pale yellow product, i.e., a flame-retardant polyol, was obtained, denoted as ESO-Si-DOPO-2. Its hydroxyl value was 170 mg KOH / g. The hydroxyl value of this invention was determined using the national standard GB12008.3-89 method. Analysis of ESO-Si-DOPO-2 in this embodiment by nuclear magnetic resonance hydrogen spectroscopy and infrared spectroscopy showed that the obtained product included… Figure 1 Products 3 and 4 are shown, and the molar ratio of product 3 to product 4 is 2:1.

[0071] A polyurethane material, the preparation method of which includes the following steps: (1) Weigh 10g of castor oil using an electronic balance and add it to a three-necked bottle.

[0072] (2) After drying 5g of the ESO-Si-DOPO-2 obtained above, add the castor oil reaction solution from step (1) above, disperse it evenly, heat it to 80°C, react for 3 hours, and then cool it to room temperature to obtain the initial product.

[0073] (3) Weigh 7.05g of PAPI and the initial product of (2) above into a beaker using an electronic balance, stir evenly in a constant temperature water bath at 30℃ for 1 / 2 hour until uniformly dispersed; pour into a mold for casting, cure at 60℃ for 12 hours, and cure at 80℃ for 2 hours to obtain a standard sample of polyurethane material.

[0074] Example 3 A flame-retardant polyol is prepared by the following steps: (1) Preparation of modified epoxidized soybean oil (ESO-Si) 100g of epoxidized soybean oil (epoxidation value: 6.3%) was placed in a three-necked round-bottom flask equipped with a condenser and thermometer. Nitrogen gas was purged to remove any trace amounts of oxygen and water. Under nitrogen inert gas protection, 200g of toluene and 20g of APTMS were added. The mixture was heated to 100°C and stirred for 24 hours to obtain the first-step product. Analysis of the first-step product prepared in this example by 1H NMR spectroscopy and infrared spectroscopy revealed that the obtained product includes... Figure 1 The product 1 and product 2 are shown, and the molar ratio of product 1 to product 2 is 2:1.

[0075] (2) The modified epoxidized soybean oil (ESO-Si, the first step product) was added to a three-necked flask, protected with nitrogen, and then heated to 100°C. 20g of DOPO was gradually added to the reaction mixture and stirred for half an hour to ensure that the molten DOPO was completely and uniformly dispersed in the modified epoxidized soybean oil. The mixture was then heated to 160°C for further reaction and kept at that temperature for 12 hours. The temperature was then lowered to approximately 25°C, 100g of water was added, and the mixture was stirred and washed. After standing and separating into layers, the water layer was removed, and the organic layer was removed by rotary evaporation to remove the solvent. Finally, a transparent, pale yellow product, i.e., a flame-retardant polyol, was obtained, denoted as ESO-Si-DOPO-3. Its hydroxyl value was 195 mg KOH / g. The hydroxyl value of this invention was determined using the national standard GB12008.3-89 method. Analysis of ESO-Si-DOPO-3 in this embodiment by nuclear magnetic resonance hydrogen spectroscopy and infrared spectroscopy showed that the obtained product included… Figure 1 Products 3 and 4 are shown, and the molar ratio of product 3 to product 4 is 2:1.

[0076] A polyurethane material, the preparation method of which includes the following steps: (1) Weigh 10g of castor oil using an electronic balance and add it to a three-necked flask; (2) After drying 5g of the ESO-Si-DOPO-3 prepared above, add the castor oil reaction solution from step (1) above, disperse it evenly, heat it to 80°C, react for 3 hours, and then cool it to room temperature to obtain the initial product. (3) Weigh 7.45g of PAPI and the initial product of (2) above into a beaker using an electronic balance, stir evenly in a constant temperature water bath at 30℃ for 1 / 2 hour until uniformly dispersed; pour into a mold for casting, cure at 60℃ for 12 hours, and cure at 80℃ for 2 hours to obtain a standard sample of polyurethane material.

[0077] Example 4 A flame-retardant polyol, ESO-Si-DOPO-1, was prepared in the same manner as in Example 1.

[0078] A polyurethane material, the preparation method of which includes the following steps: (1) Weigh 10g of castor oil using an electronic balance and add it to a three-necked flask; (2) After drying 3g of the ESO-Si-DOPO-1 prepared above, add the castor oil reaction solution from step (1) above, disperse it evenly, heat it to 80°C, react for 3 hours, and then cool it to room temperature to obtain the initial product. (3) Weigh 6.06g of PAPI isocyanate resin and the above (2) initial product into a beaker using an electronic balance, stir evenly in a 30℃ constant temperature water bath for 1 / 2 hour until uniformly dispersed; pour into a mold for casting, cure at 60℃ for 12 hours, and cure at 80℃ for 2 hours to obtain a polyurethane material standard sample.

[0079] Example 5 A flame-retardant polyol, ESO-Si-DOPO-1, was prepared in the same manner as in Example 1.

[0080] A polyurethane material, the preparation method of which includes the following steps: (1) Weigh 10g of castor oil using an electronic balance and add it to a three-necked flask; (2) After drying 10g of the above-prepared ESO-Si-DOPO-1, add it to the above reaction solution, disperse it evenly, heat it to 80℃, react for 3h, and then cool it to room temperature to obtain the initial product. (3) Weigh 9.89g of PAPI isocyanate resin and the above (2) initial product into a beaker using an electronic balance, stir evenly in a 30℃ constant temperature water bath for 1 / 2 hour until uniformly dispersed; pour into a mold for casting, cure at 60℃ for 12 hours, and cure at 80℃ for 2 hours to obtain a polyurethane material standard sample.

[0081] Comparative Example 1 A polyurethane material, the preparation method of which includes the following steps: (1) Weigh 10g of castor oil using an electronic balance and add it to a three-necked flask; (2) Weigh 4.63 g of PAPI isocyanate resin and castor oil (1) above into a three-necked bottle using an electronic balance. Stir the mixture in a 30°C constant temperature water bath for 1 / 2 hour until it is evenly dispersed. Pour the mixture into a mold and cast it into shape. Cure at 60°C for 12 hours and at 80°C for 2 hours to obtain a standard sample of polyurethane material.

[0082] Comparative Example 2 A polyurethane material, the preparation method of which includes the following steps: (1) Weigh 10g of castor oil using an electronic balance and add it to a three-necked flask; (2) After adding 5g of aluminum hydroxide and drying, add the castor oil reaction solution from step (1) above, disperse it evenly, heat it to 80°C, react for 3 hours, and then cool it to room temperature to obtain the initial product. (3) Weigh 4.63 g of PAPI isocyanate resin and the initial product of (2) above into a beaker using an electronic balance, stir evenly in a constant temperature water bath at 30℃ for 1 / 2 hour until uniformly dispersed; pour into a mold for casting, cure at 60℃ for 12 hours, and cure at 80℃ for 2 hours to obtain a standard sample of polyurethane material.

[0083] Comparative Example 3 A polyurethane material, the preparation method of which includes the following steps: (1) Weigh 10g of castor oil using an electronic balance and add it to a three-necked flask; (2) After drying 5g of DOPO, add the castor oil reaction solution from step (1) above, disperse it evenly, heat it to 80°C, react for 3 hours, and then cool it to room temperature to obtain the initial product. (3) Weigh 4.63g of PAPI isocyanate resin and the initial product of (2) above into a beaker using an electronic balance, stir evenly in a constant temperature water bath at 30℃ for 1 / 2 hour until uniformly dispersed; pour into a mold for casting, cure at 60℃ for 12 hours, and cure at 80℃ for 2 hours to obtain a standard sample of polyurethane material.

[0084] Comparative Example 4 A polyurethane material, the preparation method of which includes the following steps: (1) Weigh 10g of castor oil using an electronic balance and add it to a three-necked flask; (2) After drying 2g of aluminum hydroxide and 3g of ESO-Si-DOPO-1 prepared in Example 1, add the above reaction solution, disperse evenly, heat to 80°C, react for 3h, and cool to room temperature to obtain the initial product; (3) Weigh 7.25g of PAPI isocyanate resin and the initial product of (2) above into a beaker using an electronic balance, stir evenly in a 30℃ constant temperature water bath for 1 / 2 hour until uniformly dispersed; pour into a mold for casting, cure at 60℃ for 12 hours, and cure at 80℃ for 2 hours to obtain a standard sample of polyurethane material.

[0085] Comparative Example 5 A flame-retardant polyol is prepared in a manner that is basically the same as that in Example 1, except that the epoxy value of the epoxidized soybean oil used in step (1) is 2.0% in this comparative example.

[0086] A polyurethane material is prepared in a manner that is basically the same as in Example 1, except that the flame-retardant polyol of this comparative example is used.

[0087] Comparative Example 6 A flame-retardant polyol is prepared in a manner that is basically the same as that in Example 1, except that the epoxy value of the epoxidized soybean oil used in step (1) is 7.0% in this comparative example.

[0088] A polyurethane material is prepared in a manner that is basically the same as in Example 1, except that the flame-retardant polyol of this comparative example is used.

[0089] Comparative Example 7 A flame-retardant polyol is prepared in a manner that is basically the same as in Example 1, except that the mass ratio of epoxidized soybean oil to 3-aminopropyltrimethoxysilane in step (1) is different. In this comparative example, the mass of epoxidized soybean oil is 100g and the mass of 3-aminopropyltrimethoxysilane is 60g.

[0090] A polyurethane material is prepared in a manner that is basically the same as in Example 1, except that the flame-retardant polyol of this comparative example is used.

[0091] Comparative Example 8 A flame-retardant polyol is prepared in a manner that is basically the same as in Example 1, except that the mass ratio of epoxidized soybean oil to 3-aminopropyltrimethoxysilane in step (1) is different. In this comparative example, the mass of epoxidized soybean oil is 100g and the mass of 3-aminopropyltrimethoxysilane is 5g.

[0092] A polyurethane material is prepared in a manner that is basically the same as in Example 1, except that the flame-retardant polyol of this comparative example is used.

[0093] Comparative Example 9 A flame-retardant polyol is prepared in a manner that is basically the same as in Example 1, except that in step (2), the modified epoxidized soybean oil obtained in step (1) is not heated, but 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is added directly.

[0094] A polyurethane material is prepared in a manner that is basically the same as in Example 1, except that the flame-retardant polyol of this comparative example is used.

[0095] Comparative Example 10 A flame-retardant polyol, prepared by the same method as in Example 1.

[0096] A polyurethane material is prepared in a manner that is basically the same as in Example 1, except that the mass ratio of flame-retardant polyol to castor oil in step (1) is changed. In this comparative example, the mass of flame-retardant polyol is 2g and the mass of castor oil is 10g.

[0097] Comparative Example 11 A flame-retardant polyol, prepared by the same method as in Example 1.

[0098] A polyurethane material is prepared in a manner that is basically the same as in Example 1, except that the mass ratio of flame-retardant polyol to castor oil in step (1) is changed. In this comparative example, the mass of flame-retardant polyol is 12g and the mass of castor oil is 10g.

[0099] Test example: The mechanical properties of the polyurethane cured products obtained in Examples 1-4 and Comparative Examples 1-11 were determined. The specific procedure for mechanical property testing was as follows: Standard specimens were prepared using the template method: The polyurethane cured products obtained in Examples 1-4 and Comparative Examples 1-11 were poured into a polytetrafluoroethylene mold and cured to form dumbbell-shaped bending specimens. The mechanical properties of the standard specimens were then tested. A CMT4304 electronic universal testing machine (Shenzhen Xin Sansi Materials Testing Co., Ltd.) was used, with the tensile speed set to 2 mm / min. Tensile strength and tensile strength were determined and calculated according to GB / T 1040-2008. A vertical burning test was conducted according to ASTM D635 UL-94. The limiting oxygen index was determined using the top-side ignition method according to ASTM D2863. Density was measured by mass / volume of the specimen. The test results are shown in Table 1.

[0100] Table 1. Performance test table of polyurethane specimens in embodiments and comparative examples of the present invention.

[0101] As shown in Table 1, the introduction of ESO-Si-DOPO significantly improves the combustion dripping problem of polyurethane elastomers, and the flame retardant prepared by this invention has a better flame retardant effect than the conventional flame retardant aluminum hydroxide. Figure 2 It can also be seen that the cross-sectional density of the polyurethane material prepared by this invention is significantly improved after combustion, which can block the transfer of oxygen and heat, thus achieving a flame-retardant effect and indicating no combustion dripping. Simultaneously, in terms of mechanical properties, the polyurethane elastomer with the flame-retardant polyol of this invention is superior to the system with aluminum hydroxide. This may be because the inorganic flame retardant is unevenly dispersed within the polyurethane matrix. The flame-retardant polyol of this invention, however, has chemical bonds, which can effectively exert a synergistic reinforcing effect and improve the strength of the polyurethane. Furthermore, the polyurethane elastomer with the flame retardant of this invention has a lower density than the polyurethane elastomer prepared with inorganic flame retardants, which is significant for the material's lightweight nature. In summary, the modified polyurethane elastomer prepared by this invention not only has excellent flame-retardant properties but also maintains good mechanical properties and is lightweight, showing promising application prospects.

[0102] The above description is merely a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It is understood that other improvements and variations that are directly derived or conceived by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included within the protection scope of the present invention.

Claims

1. A method for preparing a flame-retardant polyol, characterized in that, Includes the following steps: S1: Add solvent and 3-aminopropyltrimethoxysilane to epoxidized soybean oil, and react after heating to obtain modified epoxidized soybean oil; S2: Add 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to the modified epoxidized soybean oil obtained in step S1, stir evenly, heat up to react, and after the reaction is completed, cool down to obtain flame-retardant polyol.

2. The preparation method according to claim 1, characterized in that, In S1, the epoxy value of the epoxidized soybean oil is 3.0% to 6.8%, preferably 5.0% to 6.5%.

3. The preparation method according to claim 1, characterized in that, In S1, the solvent includes at least one of toluene, xylene, ethyl acetate, and n-hexane; The mass ratio of the epoxidized soybean oil to the solvent is 1:1~10; The mass ratio of the epoxidized soybean oil to the 3-aminopropyltrimethoxysilane is 10~2:1, preferably 6~3:

1.

4. The preparation method according to claim 1, characterized in that, In S1, the reaction temperature is 40~120℃, preferably 60~80℃; and / or, The reaction time is 4 to 48 hours, preferably 8 to 24 hours.

5. The preparation method according to claim 1, characterized in that, In S2, the mass ratio of the modified epoxidized soybean oil to the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 10~0.2:1, preferably 6~4:1; The 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is added after heating the modified epoxidized soybean oil obtained in step S1 to 80~120℃.

6. The preparation method according to claim 1, characterized in that, In S2, the reaction temperature is 80~180℃, preferably 120~160℃; and / or, The reaction time is 4 to 24 hours, preferably 6 to 12 hours.

7. A flame-retardant polyol prepared by the preparation method according to any one of claims 1-6, characterized in that, The flame-retardant polyol has a hydroxyl value of 170~195 mg KOH / g.

8. A method for preparing a polyurethane material, characterized in that, Includes the following steps: (1) Add flame-retardant polyol to oil polyol, disperse and heat to react. After the reaction is completed, cool to room temperature to obtain the initial product; (2) The initial product is stirred and dispersed with isocyanate, cast and cured to obtain polyurethane material.

9. The preparation method according to claim 8, characterized in that, In step (1), the mass ratio of the flame-retardant polyol to the oil polyol is 3~10:10; Preferably, the oil polyol includes at least one of castor oil, modified soybean oil, and palm oil; The heating reaction is carried out at a temperature of 75-85°C, and / or, The heating reaction time is 2-4 hours; In step (2), the isocyanate includes at least one of polymethylene polyphenyl isocyanate, or diphenylmethane diisocyanate, or toluene diisocyanate; The mass ratio of the isocyanate to the flame-retardant polyol in step (1) is 4~15:5; The curing process involves curing at a first temperature for time t1, then raising the temperature to a second temperature and curing for time t2. The first temperature is 40~80℃; and / or, t1 is 10~14h; The second temperature is 75~85℃, and / or the t2 is 1~3h.

10. A polyurethane material prepared by the preparation method according to any one of claims 8-9.

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