Halogen-free flame-retardant polyether polyols and methods for making the same

Abstract

The application belongs to the technical field of polyether polyol preparation, and particularly relates to a halogen-free flame-retardant polyether polyol and a preparation method thereof. Tri(2-hydroxyethyl) isocyanurate, a double-hydroxyl initiator monomer containing a pyrene side chain and ethylene glycol are added into a high-pressure reaction kettle, an alkali metal catalyst is then added, dehydration is carried out for 1-2 hours, under stirring, aminopropyl-terminated polysiloxane is added into the kettle, propylene oxide is then slowly added, the pressure in the kettle is maintained at 0.3-0.5 MPa, reaction is carried out at 100-120 DEG C for 2-4 hours, and polyether polyol is obtained after refining treatment. In the application, the polyether polyol does not contain halogen, tri(2-hydroxyethyl) isocyanurate is used as one of initiators, and the triazine ring can improve the flame-retardant effect of the polyether polyol.

Description

Technical Field

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

[0002] Currently, flame retardants for polyurethane products are classified into additive flame retardants and reactive flame retardants. Additive flame retardants are added physically, and the flame retardant components do not participate in the reaction. Although they can achieve good flame retardant effects, they significantly damage the mechanical properties and processing performance of the substrate itself in the formulation. Moreover, the flame retardant will migrate and precipitate from the polyurethane material over time, causing the flame retardancy of the polyurethane material to gradually decrease or even lose its flame retardant effect.

[0003] Reactive flame retardants contain both flame-retardant elements and reactive groups. They can be used directly as raw materials to participate in polyurethane chemical reactions, becoming fixed in the material matrix through chemical bonds, thus providing a long-lasting flame-retardant effect. Examples include flame-retardant polyether polyols or flame-retardant isocyanates.

[0004] However, most commercially available reactive flame-retardant polyether polyols contain halogens, which produce large amounts of smoke and toxic, corrosive hydrogen halide gases during a fire, causing secondary hazards. Therefore, introducing halogen-free flame-retardant elements (such as phosphorus and nitrogen) into them to prepare reactive halogen-free flame-retardant polyether polyols has become an urgent problem to be solved in polyurethane materials. Summary of the Invention

[0005] The purpose of this invention is to provide a halogen-free flame-retardant polyether polyol and its preparation method to solve the above-mentioned technical problems.

[0006] To achieve the above-mentioned technical objectives, the technical solution of the present invention is as follows:

[0007] A method for preparing a halogen-free flame-retardant polyether polyol involves adding tris(2-hydroxyethyl) isocyanurate, a dihydroxy initiator monomer containing a pyrene side chain, and ethylene glycol to a high-pressure reactor, followed by the addition of an alkali metal catalyst. The mixture is heated to 100-120°C under a nitrogen atmosphere and dehydrated at -0.095 MPa for 1-2 hours. The system temperature is then lowered to 90-110°C, and an aminopropyl-terminated polysiloxane is added under stirring. Propylene oxide is then slowly added while maintaining the reactor pressure at 0.3-0.5 MPa. The reaction continues at 100-120°C for 2-4 hours. After purification, the polyether polyol is obtained.

[0008] The molecular weight of the aminopropyl-terminated polysiloxane is 500~1960 g / mol;

[0009] The structural formula of the dihydroxy initiator monomer containing the pyrene side chain is:

[0010] ;

[0011] Wherein, R1 is an alkyl chain with 1 to 3 carbon atoms, and R2 is methyl, ethyl or n-propyl.

[0012] As a further improvement, by weight, the aminopropyl-terminated polysiloxane comprises 16-19 parts, tris(2-hydroxyethyl) isocyanurate comprises 21-25 parts, dihydroxy initiator monomer containing pyrene side chain comprises 7-9 parts, ethylene glycol comprises 4-6 parts, and propylene oxide comprises 110-125 parts.

[0013] As a further improvement, the preparation method of the aminopropyl-terminated polysiloxane is as follows: Under an argon atmosphere, octamethylcyclotetrasiloxane, potassium hydroxide and dimethyl sulfoxide are mixed and gradually heated to 90~95℃ under stirring, and reacted for 1~2h. Then, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane is added, and the temperature is further increased to 110~115℃ to continue the reaction for 6~8h. After the reaction is completed, the temperature is cooled to 30~40℃, glacial acetic acid is added and reacted for 3~4h. Then, the precipitate is removed by vacuum distillation to obtain the aminopropyl-terminated polysiloxane.

[0014] As a further improvement, the molar ratio of octamethylcyclotetrasiloxane to 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane is 1.15 to 6:1, the amount of potassium hydroxide added is 0.2 to 0.5% of the mass of octamethylcyclotetrasiloxane, and the amount of dimethyl sulfoxide added is 1 to 1.5% of the mass of octamethylcyclotetrasiloxane.

[0015] As a further improvement, the preparation method of the dihydroxy initiator monomer containing pyrene side chain is as follows: γ-oxo-1-pyrene butyric acid, 1-ethyl(3-dimethyloxypropyl)carbodiamine hydrochloride and 1-hydroxybenzotriazole are added to anhydrous DMF to dissolve, and then the mixture is stirred in an ice-water bath for 1 h. After removing the ice-water bath, amino glycol and potassium carbonate are added to the mixture, and the mixture is stirred at room temperature for 20-26 h. The system is then added to deionized water, filtered under reduced pressure, and the precipitate is dried to obtain the dihydroxy initiator monomer containing pyrene side chain.

[0016] As a further improvement, the molar ratio of γ-oxo-1-pyrenebutyric acid, 1-ethyl(3-dimethyloxypropyl)carbodiamine hydrochloride and 1-hydroxybenzotriazole is 1:1.1~1.3:1.1~1.3, the molar ratio of γ-oxo-1-pyrenebutyric acid and the aminodiol is 1:1.5~1.8, and the molar ratio of potassium carbonate and γ-oxo-1-pyrenebutyric acid is 1.8~2.5:1.

[0017] As a further improvement, the amount of alkali metal catalyst added is 0.4~0.8% of the total mass of the initiator and propylene oxide, and the alkali metal catalyst is potassium hydroxide, sodium hydroxide or sodium methoxide.

[0018] The present invention also provides a halogen-free flame-retardant polyether polyol.

[0019] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows:

[0020] This invention provides a halogen-free flame-retardant polyether polyol and its preparation method. The polyether polyol does not contain halogens and uses tris(2-hydroxyethyl) isocyanurate as one of the initiators. The triazine ring in the triazine ring can improve the flame-retardant effect of the polyether polyol.

[0021] However, the introduction of triazine rings leads to a decrease in the flexibility of polyether polyol segments. In the later preparation of polyurethane materials, the elastic modulus of the polyurethane materials increases, but the elongation at break decreases significantly. This invention improves the flexibility of polyether polyol segments by introducing polysiloxanes into the polyether polyol main chain, thus compensating for the defects caused by the introduction of triazine rings into polyether polyols.

[0022] The introduction of polysiloxane segments can improve the tensile strength and elongation at break of polyurethane materials to a certain extent. However, the introduction of polysiloxane segments will exacerbate the microphase separation of soft and hard segments in polyurethane materials, and the elongation at break of polyurethane materials still cannot achieve the expected effect. Therefore, in this invention, pyrene groups are introduced into the side chains of polyether polyols. Their π-π stacking characteristics form dynamic non-covalent physical crosslinking points in polyurethane materials, further improving the tensile strength and elongation at break of polyurethane materials and making up for the defects brought about by polysiloxane segments and triazine rings.

[0023] In the polyether polyol prepared in this invention, N and Si form a synergistic flame retardant effect, further improving the flame retardant effect of the polyether polyol. At the same time, the introduction of pyrene group can further improve the thermal stability of the polyether polyol. Attached Figure Description

[0024] Figure 1 This is the infrared spectrum of the aminopropyl-terminated polysiloxane in Example 1 of the present invention;

[0025] Figure 2 This is the infrared spectrum of the dihydroxy initiator monomer containing a pyrene side chain in Example 1 of the present invention;

[0026] Figure 3 It is the structural formula of the dihydroxy initiator monomer containing pyrene side chain prepared in Examples 1 and 4-11 of this invention;

[0027] Figure 4These are the TG curves of the polyurethane elastomers prepared from polyether polyols in Example 1 and Comparative Examples 1-3 of this invention. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0029] Example 1: A method for preparing a halogen-free flame-retardant polyether polyol, comprising the following steps:

[0030] S1. Preparation of aminopropyl-terminated polysiloxanes;

[0031] Under an argon atmosphere, 100 g of 0.34 mol of octamethylcyclotetrasiloxane, 0.27 g of potassium hydroxide, and 1.34 g of dimethyl sulfoxide were mixed and gradually heated to 95 °C with stirring. The mixture was reacted for 1 h. Then, 0.13 mol of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane was added, and the mixture was heated to 110 °C and reacted for another 8 h. After the reaction was completed, the mixture was cooled to 40 °C, and 1.8 mmol of glacial acetic acid was added and reacted for 4 h to neutralize the potassium hydroxide. The mixture was then distilled under reduced pressure at 180 °C for 1 h, cooled to room temperature, and filtered to remove the precipitate, yielding an aminopropyl-terminated polysiloxane.

[0032] The structural formula of the aminopropyl-terminated polysiloxane is:

[0033] ;

[0034] The molecular weight of the aminopropyl-terminated polysiloxane is 970 g / mol;

[0035] like Figure 1 The image shown is the infrared spectrum of an aminopropyl-terminated polysiloxane. Figure 1 It can be seen that 1260cm -1 The absorption peaks are located near the stretching vibrations of the Si-C bond, ranging from 1023 to 1094 cm⁻¹. -1 The absorption peak for the stretching vibration of Si-O-Si is within the range of 3701 cm⁻¹. -1 The absorption peak of NH is located nearby;

[0036] S2. Preparation of dihydroxyl initiator monomers containing pyrene side chains;

[0037] 4 mmol of γ-oxo-1-pyrene butyric acid, 5 mmol of 1-ethyl(3-dimethyloxypropyl)carbodiamine hydrochloride and 5 mmol of 1-hydroxybenzotriazole were added to 150 mL of anhydrous DMF (N,N-dimethylformamide) to dissolve them. The mixture was then stirred in an ice-water bath for 1 h. After removing the ice-water bath, 7 mmol of aminodiol and 8 mmol of potassium carbonate were added to the mixture. The mixture was stirred at room temperature for 24 h. The mixture was then added to 500 mL of deionized water and filtered under reduced pressure. The precipitate was dried under vacuum at 60 °C to obtain a dihydroxy initiator monomer containing a pyrene side chain.

[0038] Among them, the aminodiol is 2-amino-2-methyl-1,3-propanediol;

[0039] The obtained dihydroxy initiator monomer containing a pyrene side chain has the following structural formula:

[0040] ;

[0041] like Figure 2 The image shown is the infrared spectrum of a dihydroxy initiator monomer containing a pyrene side chain. Figure 2 It can be seen that at 800cm -1 A pyrene absorption peak appeared nearby, at 1050 cm⁻¹. -1 The characteristic peak of primary alcohol appeared nearby, at 1650 cm⁻¹. -1 Characteristic peaks of amide groups appeared nearby;

[0042] S3. Preparation of polyether polyols;

[0043] 230g of tris(2-hydroxyethyl) isocyanurate, 80g of a dihydroxy initiator monomer containing a pyrene side chain, and 50g of ethylene glycol were added to a high-pressure reactor. Then, 10.2g of alkali metal catalyst potassium hydroxide was added. The temperature was raised to 110℃ under a nitrogen atmosphere and dehydrated for 1.5h at -0.095MPa. The system temperature was then lowered to 90℃, and 180g of aminopropyl-terminated polysiloxane was added under stirring. Then, 1160g of propylene oxide was slowly added, maintaining the pressure inside the reactor at 0.4MPa. The reaction was continued at 110℃ for 3h. After the reaction was completed, the reaction system was cooled to 90℃ and vacuum-extracted at -0.095MPa for 1h to remove unreacted propylene oxide and a small amount of byproducts. After neutralization, adsorption, crystallization, and filtration purification, polyether polyol was obtained.

[0044] Specifically, the refining process is based on existing technology;

[0045] The polyether polyol has a number-average molecular weight of 790 g / mol and an average functionality of 2.42.

[0046] Example 2 A method for preparing a halogen-free flame-retardant polyether polyol, comprising the following steps:

[0047] S1. Preparation of aminopropyl-terminated polysiloxanes;

[0048] Under an argon atmosphere, 100 g of 0.34 mol of octamethylcyclotetrasiloxane, 0.2 g of potassium hydroxide, and 1 g of dimethyl sulfoxide were mixed and gradually heated to 90 °C with stirring. The mixture was reacted for 2 h. Then, 0.057 mol of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane was added, and the mixture was heated to 115 °C and reacted for another 6 h. After the reaction was completed, the mixture was cooled to 30 °C, and 1.8 mmol of glacial acetic acid was added and reacted for 3 h to neutralize the potassium hydroxide. The mixture was then distilled under reduced pressure at 180 °C for 1 h, cooled to room temperature, and filtered to remove the precipitate, yielding an aminopropyl-terminated polysiloxane.

[0049] The structural formula of the aminopropyl-terminated polysiloxane is:

[0050] ;

[0051] The molecular weight of the aminopropyl-terminated polysiloxane is 1960 g / mol;

[0052] S2. Preparation of dihydroxyl initiator monomers containing pyrene side chains;

[0053] 4 mmol of γ-oxo-1-pyrene butyric acid, 5.2 mmol of 1-ethyl(3-dimethyloxypropyl)carbodiamine hydrochloride and 5.2 mmol of 1-hydroxybenzotriazole were added to 150 mL of anhydrous DMF (N,N-dimethylformamide) to dissolve them. The mixture was then stirred in an ice-water bath for 1 h. After removing the ice-water bath, 7.2 mmol of aminodiol and 10 mmol of potassium carbonate were added to the mixture. The mixture was stirred at room temperature for 26 h. The mixture was then added to 500 mL of deionized water and filtered under reduced pressure. The precipitate was dried under vacuum at 60 °C to obtain a dihydroxy initiator monomer containing a pyrene side chain.

[0054] Among them, the aminodiol is 2-amino-2-methyl-1,3-propanediol;

[0055] S3. Preparation of polyether polyols;

[0056] 210g of tris(2-hydroxyethyl) isocyanurate, 70g of a dihydroxy initiator monomer containing a pyrene side chain, and 40g of ethylene glycol were added to a high-pressure reactor. Then, 12.64g of alkali metal catalyst sodium hydroxide was added. The temperature was raised to 100℃ under a nitrogen atmosphere and dehydrated for 2h at -0.095MPa. The system temperature was then lowered to 95℃, and 160g of aminopropyl-terminated polysiloxane was added under stirring. Then, 1100g of propylene oxide was slowly added, maintaining the pressure inside the reactor at 0.5MPa. The reaction was continued at 110℃ for 4h. After the reaction was completed, the reaction system was cooled to 90℃ and vacuum-extracted for 1h at -0.095MPa to remove unreacted propylene oxide and a small amount of byproducts. After neutralization, adsorption, crystallization, and filtration purification, polyether polyol was obtained.

[0057] Example 3 A method for preparing a halogen-free flame-retardant polyether polyol, comprising the following steps:

[0058] S1. Preparation of aminopropyl-terminated polysiloxanes;

[0059] Under an argon atmosphere, 100 g of 0.34 mol of octamethylcyclotetrasiloxane, 0.5 g of potassium hydroxide, and 1.5 g of dimethyl sulfoxide were mixed and gradually heated to 90 °C with stirring. The mixture was reacted for 1.5 h. Then, 0.29 mol of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane was added, and the mixture was heated to 112 °C and reacted for another 7 h. After the reaction was completed, the mixture was cooled to 35 °C, and 1.8 mmol of glacial acetic acid was added and reacted for 3.5 h to neutralize the potassium hydroxide. The mixture was then distilled under reduced pressure at 180 °C for 1 h, cooled to room temperature, and filtered to remove the precipitate, yielding an aminopropyl-terminated polysiloxane.

[0060] The structural formula of the aminopropyl-terminated polysiloxane is:

[0061] ;

[0062] The molecular weight of the aminopropyl-terminated polysiloxane is 500 g / mol;

[0063] S2. Preparation of dihydroxyl initiator monomers containing pyrene side chains;

[0064] 4 mmol of γ-oxo-1-pyrene butyric acid, 4.4 mmol of 1-ethyl(3-dimethyloxypropyl)carbodiamine hydrochloride and 4.4 mmol of 1-hydroxybenzotriazole were added to 150 mL of anhydrous DMF (N,N-dimethylformamide) to dissolve them. The mixture was then stirred in an ice-water bath for 1 h. After removing the ice-water bath, 6 mmol of aminodiol and 7.2 mmol of potassium carbonate were added to the mixture. The mixture was stirred at room temperature for 20 h. The mixture was then added to 500 mL of deionized water and filtered under reduced pressure. The precipitate was dried under vacuum at 60 °C to obtain a dihydroxy initiator monomer containing a pyrene side chain.

[0065] Among them, the aminodiol is 2-amino-2-methyl-1,3-propanediol;

[0066] S3. Preparation of polyether polyols;

[0067] 250g of tris(2-hydroxyethyl) isocyanurate, 90g of a dihydroxy initiator monomer containing a pyrene side chain, and 60g of ethylene glycol were added to a high-pressure reactor. Then, 7.36g of alkali metal catalyst sodium methoxide was added. The temperature was raised to 120℃ under a nitrogen atmosphere and dehydrated for 1h at -0.095MPa. The system temperature was then lowered to 110℃, and 190g of aminopropyl-terminated polysiloxane was added under stirring. Then, 1250g of propylene oxide was slowly added, maintaining the pressure inside the reactor at 0.3MPa. The reaction was continued at 120℃ for 2h. After the reaction was completed, the reaction system was cooled to 90℃ and vacuum-extracted for 1h at -0.095MPa to remove unreacted propylene oxide and a small amount of byproducts. After neutralization, adsorption, crystallization, and filtration purification, polyether polyol was obtained.

[0068] Examples 4-11 provide a method for preparing halogen-free flame-retardant polyether polyols. The specific steps are the same as in Example 1. The difference is that the amino diols used in the preparation of the dihydroxy initiator monomer containing the pyrene side chain are different. The amino diols used in Examples 4-12 are shown in Table 1.

[0069] Table 1. Amino diols used in Examples 4-11

[0070]

[0071] like Figure 3 The diagram shows the structural formula of the dihydroxy initiator monomer containing a pyrene side chain prepared in Examples 1 and 4-11.

[0072] Comparative Example 1 This comparative example provides a method for preparing a halogen-free flame-retardant polyether polyol. The specific steps are the same as in Example 1, except that in step S3, during the preparation of the polyether polyol, aminopropyl-terminated polysiloxane is not added to the initiator. Specifically:

[0073] 230g of tris(2-hydroxyethyl) isocyanurate, 80g of a dihydroxy initiator monomer containing a pyrene side chain, and 50g of ethylene glycol were added to a high-pressure reactor. Then, 10.2g of alkali metal catalyst potassium hydroxide was added. The temperature was raised to 110℃ under a nitrogen atmosphere, and dehydration was carried out at -0.095MPa for 1.5h. Then, 1160g of propylene oxide was slowly added, and the pressure inside the reactor was maintained at 0.4MPa. The reaction was carried out at 110℃ for 3h. After the reaction was completed, the reaction system was cooled to 90℃ and vacuum extracted at -0.095MPa for 1h to remove unreacted propylene oxide and a small amount of by-products. After neutralization, adsorption, crystallization, and filtration purification, polyether polyol was obtained.

[0074] Comparative Example 2 This comparative example provides a method for preparing a halogen-free flame-retardant polyether polyol. The specific steps are the same as in Example 1, except that in step S3, during the preparation of the polyether polyol, a dihydroxyl initiator monomer containing a pyrene side chain is not added to the initiator. Specifically:

[0075] 230g of tris(2-hydroxyethyl) isocyanurate and 50g of ethylene glycol were added to a high-pressure reactor, followed by 10.2g of potassium hydroxide, an alkali metal catalyst. The mixture was heated to 110℃ under a nitrogen atmosphere and dehydrated at -0.095MPa for 1.5h. The system temperature was then lowered to 90℃, and 180g of aminopropyl-terminated polysiloxane was added under stirring. Then, 1160g of propylene oxide was slowly added, maintaining the pressure inside the reactor at 0.4MPa. The reaction was continued at 110℃ for 3h. After the reaction was completed, the reaction system was cooled to 90℃ and vacuum-extracted at -0.095MPa for 1h to remove unreacted propylene oxide and a small amount of byproducts. The mixture was then purified by neutralization, adsorption, crystallization, and filtration to obtain polyether polyol.

[0076] Comparative Example 3 This comparative example provides a method for preparing a halogen-free flame-retardant polyether polyol. The specific steps are the same as in Example 1, except that in step S3, during the preparation of the polyether polyol, tris(2-hydroxyethyl) isocyanurate and ethylene glycol are used as the initiators. Specifically:

[0077] 230g of tris(2-hydroxyethyl) isocyanurate and 50g of ethylene glycol were added to a high-pressure reactor, followed by 10.2g of potassium hydroxide, an alkali metal catalyst. The mixture was heated to 110℃ under a nitrogen atmosphere and dehydrated at -0.095MPa for 1.5h. Then, 1160g of propylene oxide was slowly added while maintaining the pressure inside the reactor at 0.4MPa. The reaction was continued at 110℃ for 3h. After the reaction was completed, the reaction system was cooled to 90℃ and vacuum-extracted at -0.095MPa for 1h to remove unreacted propylene oxide and a small amount of byproducts. The mixture was then purified by neutralization, adsorption, crystallization, and filtration to obtain polyether polyol.

[0078] The polyether polyols prepared in Example 1 and Comparative Examples 1-3 were used to prepare polyurethane elastomers, and the thermal stability, flame retardancy and mechanical properties of the polyurethane elastomers were tested.

[0079] The method for preparing polyurethane elastomer is as follows: 55g of polyether polyol is heated to 100~110℃ and vacuum dehydrated for 1.5h, then cooled to 60℃, 40g of 4,4´-diphenylmethane diisocyanate is added, the temperature is slowly raised to 85℃, and the reaction is carried out for 3h. When the isocyanate index reaches 6.0~6.5, vacuum degassing is performed for 30min to obtain polyurethane prepolymer.

[0080] The polyurethane prepolymer was heated to 80°C, 10g of 1,4-butanediol was added and stirred rapidly, and then the mixture was poured into a preheated mold and vulcanized at 110°C for 24 hours. After that, it was left at room temperature for 7 days to obtain the polyurethane elastomer.

[0081] The mechanical properties of polyurethane elastomers were tested according to GB / T 528-2009; the thermal stability of polyurethane elastomers was tested using a thermogravimetric analyzer with a heating rate of 10℃ / min and a heating range of 50~600℃ under a nitrogen atmosphere; the flammability of polyurethane elastomers was tested using the LOI test and the vertical burning test (UL-94).

[0082] Table 2 shows the mechanical properties of the polyurethane elastomers prepared from polyether polyols in Examples 1 and Comparative Examples 1-3.

[0083] Table 2 Mechanical properties of polyurethane elastomers

[0084]

[0085] As can be seen from Table 2, the polyurethane elastomer prepared by the polyether polyol in Comparative Example 3 has the highest elastic modulus, but its tensile strength and elongation at break are significantly lower than those in Example 1. This is because the introduction of the triazine ring in the polyether polyol results in a polyurethane elastomer with higher rigidity and lower flexibility. However, the reduction in elastic modulus in Example 1 is less than that in tensile strength and elongation at break. Therefore, the polyurethane elastomer in Example 1 has better mechanical properties.

[0086] The polyurethane elastomers prepared from polyether polyols in Comparative Examples 1 and 2 showed improved tensile strength and elongation at break compared to Comparative Example 3, but still showed a significant difference compared to those in Example 1.

[0087] like Figure 4 The figure shows the TG curves of the polyurethane elastomers prepared from polyether polyols in Example 1 and Comparative Examples 1-3.

[0088] Depend on Figure 4 It can be seen that the polyether polyols of Comparative Examples 2 and 3 did not introduce pyrene groups, and the initial decomposition temperature of the polyurethane elastomers prepared from them was lower than that of Example 1 and Comparative Example 1, indicating that the introduction of pyrene groups can improve the thermal stability of polyurethane elastomers. The polyether polyols of Comparative Examples 1 and 3 did not introduce polysiloxane segments, and the decomposition rate of the polyurethane elastomers prepared from them at high temperatures was significantly higher than that of Example 1 and Comparative Example 2. Example 1 had the highest char residue, and Comparative Example 3 had the lowest char residue, and the char residue of Comparative Example 3 and Comparative Example 1 was similar, indicating that the introduction of polysiloxane segments can further improve the char residue of polyurethane elastomers.

[0089] Table 3 shows the combustion performance test results of the polyurethane elastomers prepared from polyether polyols in Example 1 and Comparative Examples 1-3.

[0090] Table 3. Test results of the combustion performance of polyurethane elastomers

[0091]

[0092] As shown in Table 3, the polyether polyol in Example 1 has the best flame retardant effect. The flame retardant effects of the polyether polyols in Comparative Examples 1-3 all decreased to some extent. Among them, compared with Comparative Example 2, the flame retardant effect of the polyether polyol in Comparative Example 1 on polyurethane elastomer is not as good as that in Comparative Example 2. This is because no polysiloxane was introduced in Comparative Example 1, so it did not form a N and Si synergistic flame retardant effect. Therefore, the flame retardant effect of the polyether polyol in Comparative Example 1 on polyurethane elastomer is not as good as that in Example 1 and Comparative Example 2.

[0093] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a halogen-free flame-retardant polyether polyol, characterized in that, Includes the following steps: Tris(2-hydroxyethyl) isocyanurate, a dihydroxy initiator monomer containing a pyrene side chain, and ethylene glycol were added to a high-pressure reactor, followed by the addition of an alkali metal catalyst. The reactor was heated to 100-120°C under a nitrogen atmosphere and dehydrated at -0.095 MPa for 1-2 hours. The system temperature was then lowered to 90-110°C, and an aminopropyl-terminated polysiloxane was added under stirring. Propylene oxide was then slowly added, and the reactor pressure was maintained at 0.3-0.5 MPa. The reaction was continued at 100-120°C for 2-4 hours. After purification, a polyether polyol was obtained. The molecular weight of the aminopropyl-terminated polysiloxane is 500~1960 g / mol; The structural formula of the dihydroxy initiator monomer containing the pyrene side chain is: ； Wherein, R1 is an alkyl chain with 1 to 3 carbon atoms, and R2 is methyl, ethyl or n-propyl.

2. The method for preparing halogen-free flame-retardant polyether polyol according to claim 1, characterized in that, By weight, the aminopropyl-terminated polysiloxane comprises 16-19 parts, tris(2-hydroxyethyl) isocyanurate comprises 21-25 parts, dihydroxy initiator monomer containing pyrene side chain comprises 7-9 parts, ethylene glycol comprises 4-6 parts, and propylene oxide comprises 110-125 parts.

3. The method for preparing halogen-free flame-retardant polyether polyol according to claim 2, characterized in that, The preparation method of the aminopropyl-terminated polysiloxane is as follows: Under an argon atmosphere, octamethylcyclotetrasiloxane, potassium hydroxide and dimethyl sulfoxide are mixed and gradually heated to 90-95°C under stirring, and reacted for 1-2 hours. Then, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane is added, and the temperature is further increased to 110-115°C and reacted for 6-8 hours. After the reaction is completed, the temperature is cooled to 30-40°C, glacial acetic acid is added and reacted for 3-4 hours. Then, the precipitate is removed by vacuum distillation to obtain the aminopropyl-terminated polysiloxane.

4. The method for preparing halogen-free flame-retardant polyether polyol according to claim 3, characterized in that, The molar ratio of octamethylcyclotetrasiloxane to 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane is 1.15 to 6:1, the amount of potassium hydroxide added is 0.2 to 0.5% of the mass of octamethylcyclotetrasiloxane, and the amount of dimethyl sulfoxide added is 1 to 1.5% of the mass of octamethylcyclotetrasiloxane.

5. The method for preparing halogen-free flame-retardant polyether polyol according to claim 2, characterized in that, The preparation method of the dihydroxy initiator monomer containing pyrene side chain is as follows: γ-oxo-1-pyrene butyric acid, 1-ethyl(3-dimethyloxypropyl)carbodiamine hydrochloride and 1-hydroxybenzotriazole are added to anhydrous DMF to dissolve, and then the mixture is stirred in an ice-water bath for 1 h. After removing the ice-water bath, amino glycol and potassium carbonate are added to the mixture, and the mixture is stirred at room temperature for 20-26 h. The system is then added to deionized water, filtered under reduced pressure, and the precipitate is dried to obtain the dihydroxy initiator monomer containing pyrene side chain.

6. The method for preparing halogen-free flame-retardant polyether polyol according to claim 5, characterized in that, The molar ratio of γ-oxo-1-pyrenebutyric acid, 1-ethyl(3-dimethyloxypropyl)carbodiamine hydrochloride, and 1-hydroxybenzotriazole is 1:1.1~1.3:1.1~1.3; the molar ratio of γ-oxo-1-pyrenebutyric acid to the aminodiol is 1:1.5~1.8; and the molar ratio of potassium carbonate to γ-oxo-1-pyrenebutyric acid is 1.8~2.5:

1.

7. The method for preparing halogen-free flame-retardant polyether polyol according to claim 1, characterized in that, The amount of alkali metal catalyst added is 0.4-0.8% of the total mass of the initiator and propylene oxide, and the alkali metal catalyst is potassium hydroxide, sodium hydroxide or sodium methoxide.

8. A halogen-free flame-retardant polyether polyol, characterized in that, The halogen-free flame-retardant polyether polyol is prepared by the method described in claim 1.

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