Flame-retardant polyether polyol with low heat conductivity coefficient as well as preparation method and application of flame-retardant polyether polyol

Abstract

The invention belongs to the technical field of polyether polyol, and particularly relates to flame-retardant polyether polyol with a low heat conductivity coefficient as well as a preparation method and application of the flame-retardant polyether polyol. The flame-retardant polyether polyol with the low heat conductivity coefficient is obtained by polymerizing bis (2-hydroxyethyl) aminomethyl diethyl phosphonate, halogen-containing aniline and small molecular alcohol / alcohol amine as a ternary mixed initiator with alkylene oxide under the action of a catalyst, the ternary mixed initiator comprises the following components in percentage by mass: 12.15 to 22.78 percent of bis (2-hydroxyethyl) amino methyl diethyl phosphonate, 43.21 to 63.89 percent of halogen-containing aniline, and 23.96 to 34.01 percent of small molecular alcohol / alcohol amine. The polyether polyol realizes comprehensive properties of lasting flame retardance, high strength and low heat conductivity. The invention also provides a preparation method of the polyether polyol and application of the polyether polyol in rigid polyurethane foam.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polyether polyols, and particularly relates to a low-thermal-conductivity flame-retardant polyether polyol and a preparation method and application thereof. BACKGROUND

[0002] As a core raw material for synthesizing hard polyurethane foam, the traditional product has four core limitations in performance and process, which are difficult to adapt to modern high-end industrial needs: (1) Single flame-retardant system and poor durability: Traditional polyether relies on physical addition of a single flame retardant (such as triphosphate TCEP), which is easy to migrate and lose with time, resulting in a decline in flame-retardant effect of more than 15% per year, and a single halogen or phosphorus-based flame retardant requires a high addition amount to meet the standard, causing a 30% or so decrease in material mechanical properties; (2) Insufficient controllability of polymerization process: Traditional polymerization mostly uses a "one-step heating" method, which directly raises the temperature to the reaction temperature and then starts to pass in PO without activating the starter at low temperature. This causes the epoxy alkane to preferentially react with small molecule alcohols / alcohols, resulting in incomplete reaction of functional starters (such as phosphorus compounds) and high residual amount, affecting the overall performance stability of the polyether; (3) Difficulty in balancing mechanical strength and thermal insulation performance: The traditional polyether molecular chain has low crosslinking degree control precision, and the polyurethane foam made therefrom has coarse and unevenly distributed bubbles, with a compressive strength of less than 200 kPa or a thermal conductivity of more than 0.025 W / (m·K), which cannot meet the requirements of high strength and low thermal conductivity at the same time; (4) Lack of downstream foaming synergy: The existing scheme does not combine polyether modification with foaming aid design, and the functional groups in the polyether cannot form a synergistic effect with the foaming system, resulting in limited improvement of foam performance and difficulty in breaking through the industry performance bottleneck.

[0003] Chinese patent CN 113754877 A discloses a preparation method of low thermal conductivity polyether polyol, comprising the following steps: (1) the fluorine-containing compound, alcohol initiator and solid KOH are put into the reaction kettle together, sealed, nitrogen replacement heating, and propylene oxide is introduced; (2) the temperature in the reaction kettle is controlled at 80-120℃, propylene oxide is continuously added for the first time, the material temperature is controlled at 80-120℃ during the process, the pressure in the kettle is 0.1-0.4 MPa; (3) vacuum pumping to 100-150℃, continuously adding propylene oxide for the second time, the temperature is controlled at 100-150℃ during the process, the pressure in the kettle is 0.1-0.4 MPa; (4) removing unreacted monomers; (5) post-treatment, obtaining polyether polyol product. The rigid polyurethane foam prepared by using the low thermal conductivity polyether polyol has the characteristics of high activity, low thermal conductivity and good demolding property. However, the polyether polyol prepared by this method can improve the performance of rigid polyurethane foam, but the improvement of other key performances of foam plastic, such as mechanical strength and flame retardance, is not enough, and the thermal conductivity performance still has further optimization space.

[0004] Chinese patent CN 116948163 A discloses a kind of double hydroxyl DOPO halogen-free flame-retardant polyether polyol and its preparation method and application. The double hydroxyl DOPO halogen-free flame-retardant polyether polyol is obtained by using double hydroxyl DOPO and polyol as mixed initiator, and polymerizing with alkylene oxide under the action of composite catalyst, and the mass percentage of double hydroxyl DOPO in mixed initiator is 35~62%. The prepared double hydroxyl DOPO halogen-free flame-retardant polyether polyol has better mechanical strength, activity and flame retardance when used in polyurethane material compared with other polyether polyols. However, in order to better meet the increasingly stringent requirements, there is still room for improvement in mechanical strength, flame retardance and thermal conductivity. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art, provide a low thermal conductivity flame-retardant polyether polyol, realize the comprehensive performance of "long-lasting flame retardance, high strength and low thermal conductivity", and provide a preparation method thereof and its application in rigid polyurethane foam products.

[0006] The low thermal conductivity flame-retardant polyether polyol disclosed by the present application uses double (2-hydroxyethyl) aminomethyl phosphonic acid diethyl ester, halogen-containing aniline and small molecule alcohol / alcohol amine as a ternary mixed initiator, and polymerizes with alkylene oxide under the action of a catalyst to obtain the low thermal conductivity flame-retardant polyether polyol. The structure formula of the double (2-hydroxyethyl) aminomethyl phosphonic acid diethyl ester is as follows: .

[0007] Diethyl bis(2-hydroxyethyl)aminomethyl phosphonate: contains a unique phosphorus-nitrogen synergistic structure, on the one hand, through the phosphorus element, a phosphate ester flame-retardant coating is formed during combustion, which insulates oxygen and heat; on the other hand, the nitrogen element can react with halogen to generate halide amine compounds, strengthening the flame-retardant effect, and at the same time, its hydroxyl group can fully react with alkylene oxide, avoiding the problem of easy migration of traditional phosphorus-based flame retardants.

[0008] The halogen-containing aniline is one or more of 3,3'-dichloro-4,4'-diamino diphenyl methane, 4-chloro-4'-bromine diphenylamine, p-chloroaniline, 3,4-dichloroaniline, 2,5-dichloroaniline, 5-chloro-m-phenylenediamine, 4-chloro-o-phenylenediamine, p-bromoaniline, 4-bromo-2,6-dichloroaniline, 2,4-dibromoaniline, bis(4-bromophenyl)amine or 2,4-difluoroaniline. The halogen-containing aniline provides halogen elements, forming a "phosphorus-nitrogen-halogen" ternary synergistic flame retardant with the phosphorus-nitrogen structure of diethyl bis(2-hydroxyethyl)aminomethyl phosphonate, and the benzene ring structure can enhance the rigidity of the polyether molecular chain, improving the mechanical strength of the foam.

[0009] The small molecule alcohol / alcohol amine is one or more of sorbitol, 1,4-butanediol, triethanolamine, diethylene glycol, glycerol, hexanediol or propylene glycol. The small molecule alcohol / alcohol amine provides multiple hydroxyl sites to regulate the cross-linking degree of the polyether, making the subsequent foam cells more delicate; at the same time, its moderate hydroxyl activity can orderly react with other initiators and alkylene oxides, avoiding the presence of component residues during polymerization.

[0010] The mass percentage of each component of the ternary mixed initiator in the mixed initiator is: diethyl bis(2-hydroxyethyl)aminomethyl phosphonate 12.15-22.78%, halogen-containing aniline 43.21-63.89%, and small molecule alcohol / alcohol amine 23.96-34.01%; if the ratio of the ternary mixed initiator exceeds the above range, the polymerization reaction will be incomplete, and the flame retardancy, mechanical strength and thermal conductivity of the polyether will be simultaneously deteriorated.

[0011] Preferably, the catalyst is one or both of KOH and NaOH, which has stable catalytic activity and can precisely control the ring-opening polymerization rate of alkylene oxide, avoiding the problem of local overheating caused by too fast reaction; the addition amount of the catalyst is 0.21-0.39% of the total mass of the ternary mixed initiator, alkylene oxide and catalyst.

[0012] Preferably, the alkylene oxide is one or both of propylene oxide and ethylene oxide, propylene oxide provides flexibility of the polyether molecular chain, and ethylene oxide improves the hydroxyl activity, and the combination of the two can balance the viscosity and reactivity of the polyether; the mass ratio of alkylene oxide to ternary mixed initiator is (1.04-1.33):1.

[0013] The preparation method of the low-thermal-conductivity flame-retardant polyether polyol disclosed by the application is characterized by a "low-temperature segmented temperature control chain extension-high-temperature precise end capping" process, and comprises the following steps: (1) The segmented temperature control chain extension stage: double (2-hydroxyethyl) aminomethyl phosphonic acid diethyl ester, halogen-containing aniline, small molecule alcohol / alcohol amine and catalyst are put into a reaction kettle, the pressure is charged to 0.25-0.28 MPa, and the reaction kettle is tested for leakage for 35 min to ensure the sealing property of the reaction kettle; the temperature is raised to 92-95 DEG C under a negative pressure atmosphere, and the temperature is kept for 1-1.2 h to preliminarily activate the small molecule alcohol / alcohol amine; the vacuum is extracted to -0.092 to -0.105 MPa, the temperature is raised to 96-100 DEG C, and part of the epoxy alkane is added dropwise to perform segmented temperature control chain extension; after the feeding is completed, the internal pressure reaction is continued for 1.6-2.2 h to obtain a polyether polyol intermediate; in this stage, the segmented temperature control is performed to avoid the preferential reaction of the epoxy alkane with the small molecule alcohol / alcohol amine, and to ensure that the double (2-hydroxyethyl) aminomethyl phosphonic acid diethyl ester and the halogen-containing aniline fully participate in polymerization, thereby reducing the residual amount of the initiator.

[0014] (2) The high-temperature precise end capping and purification stage: the polyether polyol intermediate is raised to 118-138 DEG C, the remaining epoxy alkane is added dropwise to perform precise end capping synthesis; after the feeding is completed, the internal pressure reaction is continued for 2.2-3.2 h, the nitrogen gas is pressurized to 0.22-0.26 MPa, and the pressure is stable for more than 15 min without being reduced, which indicates that the reaction is complete; the temperature is lowered, the nitrogen gas is bubbled for 0.35-0.55 h to remove the residual small molecules; after the bubbling is completed, the temperature is lowered to 72-92 DEG C to discharge, and the low-thermal-conductivity flame-retardant polyether polyol is obtained.

[0015] In step (1), the addition amount of the epoxy alkane is 26.28-33.98% of the total mass of the epoxy alkane.

[0016] In step (1), the polymerization process adopts the "segmented temperature control chain extension" process, and the chain extension stage temperature is controlled in two stages: the first stage temperature is 92-95 DEG C, and the temperature is kept for 1-1.2 h; the second stage temperature is 96-100 DEG C, and the temperature is kept for 1.6-2.2 h, to avoid the preferential reaction of the epoxy alkane with the small molecule alcohol / alcohol amine, thereby causing the initiator residue.

[0017] In step (2), the temperature of the nitrogen gas bubbling is 82-98 DEG C, and the pressure is -0.082 to -0.092 MPa.

[0018] The low-thermal-conductivity flame-retardant polyether polyol disclosed by the application is applied to the preparation of rigid polyurethane foam.

[0019] In the preparation process of the rigid polyurethane foam, a pretreated environmentally friendly synergistic auxiliary agent needs to be added to form a four-element synergistic system with the phosphorus-nitrogen-halogen structure in the polyether polyol.

[0020] The pretreated environment-friendly synergistic auxiliary agent is one of nano magnesium hydroxide and montmorillonite, or a combination of the two, which is pretreated by a silane coupling agent (KH-550 or KH-560), and the addition amount of the pretreated environment-friendly synergistic auxiliary agent is 2.5-4.8% of the mass of the polyether polyol.

[0021] Nano magnesium hydroxide and montmorillonite are selected as the environment-friendly synergistic auxiliary agent, nano magnesium hydroxide releases water to reduce the temperature during combustion, and montmorillonite can form a lamellar barrier structure. The environment-friendly synergistic auxiliary agent needs to be pretreated by a silane coupling agent (KH-550 / KH-560), the mass ratio of the environment-friendly synergistic auxiliary agent to the silane coupling agent is (5.38-6.67):1, the pretreatment temperature is 85-95℃, and the pretreatment time is 1.5-2h. Through the reaction of the amino group / epoxy group of the coupling agent with the hydroxyl group on the surface of the auxiliary agent, the compatibility of the auxiliary agent with the polyether polyol is improved, and the agglomeration of the auxiliary agent is avoided to prevent the decline of the foam performance.

[0022] The preparation process of the rigid polyurethane foam is as follows: 100 parts of polyether polyol, pretreated environment-friendly synergistic auxiliary agent (the addition amount is 2.5-4.8% of the mass of the polyether polyol), flame retardant (TCEP), catalyst (MAYCAT PC8), water, and physical foaming agent (cyclopentane) are mixed to prepare A material; PM200 of Wanhua Chemical Group Co., Ltd. is selected as B material; A material and B material are mixed and foamed according to the -NCO index of 1.05, and rigid polyurethane foam is obtained after curing.

[0023] Compared with the prior art, the present application has the following advantages: (1) The present application first constructs a whole-chain technology system of "starter ratio optimization + temperature control during polymerization + synergistic foaming auxiliary agent", breaks through the modification limitation of traditional modification which only focuses on a single link. By fixing the ratio of the ternary starter, combining with the segmented temperature control polymerization and the pretreated environment-friendly synergistic auxiliary agent, the "phosphorus-nitrogen-halogen-inorganic" four-element synergistic flame retardation is realized, the three problems of "easy attenuation of traditional polyether flame retardation, insufficient strength, and high thermal conductivity" are solved, the foam oxygen index is ≥32.8%, the compressive strength is ≥252kPa, and the thermal conductivity is ≤0.016W / (m·K); especially suitable for building external wall insulation, cold chain truck compartment thermal insulation, electronic component packaging and other scenes with strict requirements on the comprehensive performance of "durable flame retardation, high mechanical strength and low thermal conductivity" of the material.

[0024] (2) The present application adopts the process of "low-temperature segmented temperature control chain extension + high-temperature precise end capping", and the residual starter caused by the preferential reaction of the high-activity starter is avoided by segmented temperature control, and the performance stability is significantly improved.

[0025] (3) Introducing pre-treated environmentally friendly synergistic additives to form a quaternary synergy with the phosphorus-nitrogen-halogen structure in polyether not only solves the problem of easy migration of TCEP (the annual decay rate of flame retardant effect is reduced to less than 3%), but also controls the cell diameter through the nano effect of the additives (the cell diameter is controlled at 52-62μm), making the cells more delicate, further reducing the thermal conductivity, and improving the compressive strength of the foam.

[0026] (4) The polyether polyol and polyurethane foam prepared by this invention meet the performance requirements of high-end fields and can replace imported similar products. The product cost of this invention is significantly lower than the raw material cost in the industry; at the same time, the use of environmentally friendly synergistic additives in the pretreatment reduces the amount of TCEP added, complies with the EU RoHS environmental standard, and broadens the scope of product export applications. Detailed Implementation

[0027] The present invention will be further described below with reference to the embodiments, but these embodiments do not limit the implementation of the present invention. Unless otherwise specified, all raw materials used in the embodiments are commercially available.

[0028] The following describes some of the raw materials used in the examples and comparative examples: Diethyl bis(2-hydroxyethyl)aminomethylphosphonic acid (Shanghai Aladdin Biochemical Technology Co., Ltd., purity 99.2%). Halogenated aniline (Sinopharm Chemical Reagent Co., Ltd., industrial grade); Small molecule alcohols / amines (Tianjin Kemio Chemical Reagent Co., Ltd., industrial grade); Catalyst (KOH / NaOH, analytical grade, Tianjin Damao Chemical Reagent Factory); Epoxyalkanes (propylene oxide / ethylene oxide, 99.5% purity, Wanhua Chemical Group Co., Ltd.); Environmentally friendly synergistic additives (nano magnesium hydroxide, particle size 50-80nm, Shandong Elpai Powder Technology Co., Ltd.; montmorillonite, sodium-based, Shanghai Maclean Biochemical Technology Co., Ltd.). Silane coupling agent (KH-550 / KH-560, analytical grade, Nanjing Shuguang Chemical Group Co., Ltd.).

[0029] Example 1 (1) Pretreatment of environmentally friendly synergistic additives Take 30g of nano magnesium hydroxide, add 5g of silane coupling agent KH-550, stir and pretreat at 85℃ for 1.5h to obtain pretreated nano magnesium hydroxide, dry and set aside for later use; (2) Preparation of polyether polyols Segmented temperature-controlled chain extension stage: 638.9g of 4-bromo-2,6-dichloroaniline, 121.5g of diethyl bis(2-hydroxyethyl)aminomethylphosphonic acid, 239.6g of sorbitol and 7.2g of KOH were added to the reactor; the pressure was increased to 0.25MPa and leak tested for 35min; the temperature was raised to 92℃ under negative pressure and held for 1h, then the vacuum was continued to -0.092MPa, the temperature was raised to 96℃, and 352g of ethylene oxide (accounting for 33.94% of the total ethylene oxide mass) was added dropwise; after the feeding was completed, the reaction was carried out under internal pressure for 1.6h to obtain the polyether polyol intermediate; High-temperature precision end-capping and purification stage: The intermediate was heated to 118℃, and 685g of propylene oxide was added dropwise; after the feeding was completed, the temperature was maintained and the reaction continued for 2.2h; nitrogen was purged to 0.22MPa, and after the pressure was stabilized for 15min, the temperature was lowered to 82℃; nitrogen was bubbled at -0.082MPa for 0.35h; the temperature was lowered to 72℃ and the material was discharged to obtain flame-retardant polyether polyol with low thermal conductivity; (3) Preparation of rigid polyurethane foam The raw materials were mixed to prepare component A (100 parts of polyether polyol, 4.8 parts of pretreated nano magnesium hydroxide, 18 parts of TCEP, 1.0 parts of MAYCAT PC8, 0.45 parts of water, and 22 parts of cyclopentane), and component B was PM200 from Wanhua Chemical Group Co., Ltd. Component A and component B were mixed and foamed at an -NCO index of 1.05, and foam samples were obtained after curing.

[0030] Example 2 (1) Pretreatment of environmentally friendly synergistic additives Take 25g of montmorillonite, add 4g of silane coupling agent KH-560, stir and pretreat at 95℃ for 2h to obtain pretreated montmorillonite, dry and set aside. (2) Preparation of polyether polyols Segmented temperature-controlled chain extension stage: 432.1g of 5-chloro-m-phenylenediamine, 227.8g of diethyl bis(2-hydroxyethyl)aminomethylphosphonic acid, 340.1g of glycerol and 5.1g of NaOH were added to the reactor; the pressure was increased to 0.28MPa and a leak test was performed for 35min; the temperature was raised to 95℃ under negative pressure and held for 1.2h, then the pressure was further reduced to -0.105MPa and the temperature was raised to 100℃, and 349g of ethylene oxide (accounting for 26.28% of the total ethylene oxide mass) was added dropwise; after the feeding was completed, the reaction was carried out under internal pressure for 2.2h to obtain the polyether polyol intermediate; High-temperature precision capping and purification stage: The intermediate was heated to 138℃, and 979g of propylene oxide was added dropwise; after the feeding was completed, the temperature was maintained and the reaction continued for 3.2h; nitrogen was purged to 0.26MPa, and after the pressure was stabilized for 15min, the temperature was lowered to 98℃; nitrogen was bubbled at -0.092MPa for 0.55h; the temperature was lowered to 92℃ and the material was discharged to obtain a flame-retardant polyether polyol with low thermal conductivity; (3) Preparation of rigid polyurethane foam The raw materials were mixed to prepare A material (polyether polyol 100 parts, pretreated montmorillonite 2.5 parts, TCEP 18 parts, MAYCAT PC 81.0 parts, water 0.65 parts, and cyclopentane 22 parts), and B material was PM200 from Wanhua Chemical Group Co., Ltd. A material and B material were mixed to foam at an -NCO index of 1.05, and a foam sample was obtained after curing.

[0031] Example 3 (1) Pretreatment of environmentally friendly synergistic additive 20 g of nano magnesium hydroxide was compounded with 10 g of montmorillonite, 4.5 g of silane coupling agent KH-550 / KH-560 (mass ratio 1:1) was added, and stirring pretreatment was carried out at 90°C for 1.8h to obtain a compounded pretreated additive, which was dried for standby use; (2) Preparation of polyether polyol Segmented temperature control chain extension stage: 520.0 g of 2,4-dibromoaniline, 180.0 g of bis(2-hydroxyethyl)aminomethyl phosphonic acid diethyl ester, 300.0 g of sorbitol, and 6.5 g of KOH / NaOH (mass ratio 1:1) were added to the reaction kettle; pressure was charged to 0.26 MPa and tested for 35 min; under negative pressure atmosphere, the temperature was raised to 94°C and kept for 1.1 h, then vacuum was continued to -0.10 MPa, the temperature was raised to 98°C, and 379 g of ethylene oxide (29.75% of the total mass of epoxy alkane) was added dropwise; after the feeding was completed, the internal pressure reaction was carried out for 2.0 h to obtain a polyether polyol intermediate; High-temperature precise end-capping and purification stage: the intermediate was heated to 125°C, and 895 g of propylene oxide was added dropwise; after the feeding was completed, the temperature was maintained to continue the reaction for 2.8 h; nitrogen was charged to 0.24 MPa, and the pressure was stabilized for 15 min, then the temperature was lowered to 90°C; nitrogen was bubbled at -0.088 MPa for 0.45 h; the temperature was lowered to 85°C to discharge, and a low thermal conductivity flame-retardant polyether polyol was obtained; (3) Preparation of rigid polyurethane foam The raw materials were mixed to prepare A material (polyether polyol 100 parts, compounded pretreated additive 3.5 parts, TCEP 18 parts, MAYCAT PC 81.0 parts, water 0.56 parts, and cyclopentane 22 parts), and B material was PM200 from Wanhua Chemical Group Co., Ltd. A material and B material were mixed to foam at an -NCO index of 1.05, and a foam sample was obtained after curing.

[0032] Example 4 (1) Pretreatment of environmentally friendly synergistic additive 28 g of nano magnesium hydroxide was pretreated by adding 5.2 g of silane coupling agent KH-550 at 88°C for 1.6 h to obtain pretreated nano magnesium hydroxide, which was dried for standby use; (2) Preparation of polyether polyol Segmented temperature control chain extension stage: 580.0 g of 3,3'-dichloro-4,4'-diaminodiphenyl methane, 160.0 g of bis(2-hydroxyethyl) aminomethyl phosphonic acid diethyl ester, 260.0 g of triethanolamine and 7.8 g of NaOH were put into the reaction kettle; pressure test for 35 min under 0.27 MPa; under negative pressure atmosphere, the temperature was raised to 93℃, and the temperature was kept for 1.05 h, then vacuum was continued to-0.095 MPa, the temperature was raised to 97℃, and 393 g of ethylene oxide (31.90% of the total mass of epoxy alkane) was added dropwise; after the feeding was completed, the internal pressure reaction was carried out for 1.8 h, and a polyether polyol intermediate was obtained; High-temperature precise end-capping and purification stage: the intermediate was heated to 130℃, and 839 g of propylene oxide was added dropwise; after the feeding was completed, the temperature was maintained to continue the reaction for 2.5 h; nitrogen was filled to 0.25 MPa, and the temperature was lowered to 95℃ after the pressure was stabilized for 15 min; nitrogen was bubbled under-0.085 MPa for 0.4 h; the temperature was lowered to 88℃ to discharge, and a low thermal conductivity flame-retardant polyether polyol was obtained; (3) Preparation of rigid polyurethane foam The raw materials were mixed to prepare A material (polyether polyol 100 parts, pretreated nano magnesium hydroxide 4.2 parts, TCEP 18 parts, MAYCAT PC 81.0 parts, water 0.48 parts, and cyclopentane 22 parts), and B material was PM200 from Wanhua Chemical Group Co., Ltd.; A material and B material were mixed and foamed at an-NCO index of 1.05, and foam samples were obtained after curing.

[0033] Comparative Example 1 The polyether polyol was prepared according to the process of Example 3; no pretreated synergistic auxiliary was added during the preparation of the foam, and the rest of the ingredients and process were the same as those of Example 3.

[0034] Comparative Example 2 During the preparation of the polyether polyol, the chain extension stage was directly heated to 98℃ and kept for 2.1 h (without segmentation), and the rest of the process and foam preparation were the same as those of Example 3.

[0035] Comparative Example 3 (1) Pretreatment of environmentally friendly synergistic auxiliary 20 g of nano magnesium hydroxide was mixed with 10 g of montmorillonite, 4.5 g of silane coupling agent KH-550 / KH-560 (mass ratio 1:1) was added, and stirring was carried out at 90℃ for 1.8 h, and then it was dried for standby; (2) Preparation of polyether polyol Segmented temperature control chain extension stage: 400.0g of 2,4-dibromoaniline, 100.0g of bis(2-hydroxyethyl)amino methyl phosphonic acid diethyl ester, 500.0g of sorbitol and 6.5g of KOH / NaOH (mass ratio 1:1) were put into the reaction kettle; pressure test for 35min under 0.26MPa; under negative pressure atmosphere, the temperature was raised to 94℃, and kept for 1.1h, then vacuum was continued to-0.10MPa, the temperature was raised to 98℃, and 379g of ethylene oxide (19.01% of the total mass of epoxy alkane) was added dropwise; after the feeding was completed, the internal pressure reaction was carried out for 2.0h, and a polyether polyol intermediate was obtained; High temperature precise capping and purification stage: the intermediate was heated to 125℃, and 1615g of propylene oxide was added dropwise; after the feeding was completed, the temperature was maintained for 2.8h; nitrogen was filled to 0.24MPa, and the pressure was stabilized for 15min, then the temperature was lowered to 90℃; nitrogen was bubbled under-0.088MPa for 0.45h; the temperature was lowered to 85℃ to discharge, and a low thermal conductivity flame-retardant polyether polyol was obtained; (3) Preparation of rigid polyurethane foam The raw materials were mixed to prepare A material (polyether polyol 100 parts, compound pretreatment aid 3.5 parts, TCEP 18 parts, MAYCAT PC 81.0 parts, water 0.56 parts, and cyclopentane 22 parts), and B material was PM200 from Wanhua Chemical Group Co., Ltd.; A material and B material were mixed and foamed at-NCO index 1.05, and after curing, a foam sample was obtained.

[0036] Comparative Example 4 (1) Pretreatment of environmentally friendly synergistic agent 28g of nano magnesium hydroxide was taken, 5.2g of silane coupling agent KH-550 was added, and stirring pretreatment was carried out at 88℃ for 1.6h, and after drying, it was used as a pretreatment agent; (2) Preparation of polyether polyol Segmented temperature control chain extension stage: 700.0g of 3,3'-dichloro-4,4'-diaminodiphenyl methane, 250.0g of bis(2-hydroxyethyl)amino methyl phosphonic acid diethyl ester, 50.0g of triethanolamine and 7.8g of NaOH were put into the reaction kettle; pressure test for 35min under 0.27MPa; under negative pressure atmosphere, the temperature was raised to 93℃, and kept for 1.05h, then vacuum was continued to-0.095MPa, the temperature was raised to 97℃, and 393g of ethylene oxide (40.23% of the total mass of epoxy alkane) was added dropwise; after the feeding was completed, the internal pressure reaction was carried out for 1.8h, and a polyether polyol intermediate was obtained; High temperature precise capping and purification stage: the intermediate was heated to 130℃, and 584g of propylene oxide was added dropwise; after the feeding was completed, the temperature was maintained for 2.5h; nitrogen was filled to 0.25MPa, and the pressure was stabilized for 15min, then the temperature was lowered to 95℃; nitrogen was bubbled under-0.085MPa for 0.4h; the temperature was lowered to 88℃ to discharge, and a low thermal conductivity flame-retardant polyether polyol was obtained; (3) Preparation of rigid polyurethane foam The raw materials were mixed to prepare component A (100 parts of polyether polyol, 4.2 parts of pretreated nano magnesium hydroxide, 18 parts of TCEP, 1.0 parts of MAYCAT PC8, 0.48 parts of water, and 22 parts of cyclopentane), and component B was PM200 from Wanhua Chemical Group Co., Ltd. Component A and component B were mixed and foamed at an -NCO index of 1.05, and foam samples were obtained after curing.

[0037] Comparative Example 5 During foam preparation, 20g of nano magnesium hydroxide and 10g of montmorillonite compound were added directly, and the rest of the process was the same as in Example 3.

[0038] Comparative Example 6 (1) Pretreatment of environmentally friendly synergistic additives Take 20g of nano magnesium hydroxide and 10g of montmorillonite, add 4.5g of silane coupling agent KH-550 / KH-560 (mass ratio 1:1), stir and pretreat at 90℃ for 1.8h, and dry for later use; (2) Preparation of polyether polyols Segmented temperature-controlled chain extension stage: 650.0g of 2,4-dibromoaniline, 350.0g of sorbitol, and 6.5g of KOH / NaOH (mass ratio 1:1) were added to the reactor; the reactor was pressurized to 0.26MPa for a leak test for 35 minutes; the temperature was raised to 94℃ under negative pressure and held for 1.1h; the pressure was then further reduced to -0.10MPa, and the temperature was raised to 98℃; 379g of ethylene oxide (accounting for 29.75% of the total ethylene oxide mass) was added dropwise; after the feeding was completed, the reactor was subjected to internal pressure reaction for 2.0h to obtain a polyether polyol intermediate; High-temperature precision end-capping and purification stage: The intermediate was heated to 125℃ and 895g of propylene oxide was added dropwise; after the feeding was completed, the temperature was maintained and the reaction continued for 2.8h; nitrogen was purged to 0.24MPa, and after the pressure was stabilized for 15min, the temperature was lowered to 90℃; nitrogen was bubbled at -0.088MPa for 0.45h; the temperature was lowered to 85℃ and the material was discharged to obtain flame-retardant polyether polyol with low thermal conductivity; (3) Preparation of rigid polyurethane foam The raw materials were mixed to prepare component A (100 parts of polyether polyol, 3.5 parts of compound pretreatment additive, 18 parts of TCEP, 1.0 parts of MAYCATPC8, 0.56 parts of water, and 22 parts of cyclopentane), and component B was PM200 from Wanhua Chemical Group Co., Ltd. Component A and component B were mixed and foamed at an -NCO index of 1.05, and foam samples were obtained after curing.

[0039] Performance testing 1. Basic performance testing of polyether polyols The polyether polyol properties of Examples 1-4 and Comparative Examples 1-6 were tested with reference to GB / T 12008.3-2009 (determination of hydroxyl value) and GB / T 12008.7-2010 (determination of viscosity), and the results are shown in Table 1.

[0040] Table 1. Polyether polyol basic performance indicators

[0041] 2. Hard polyurethane foam performance test (1) General performance test The general performance of the polyurethane foam was tested with reference to GB / T 8813-2020 (compressive strength), GB / T 2406.2-2009 (oxygen index), and GB / T 10294-2008 (thermal conductivity), and the results are shown in Table 2.

[0042] Table 2. General performance indicators of polyurethane foam

[0043] (2) Flame-retardant durability test of polyurethane foam To ensure the accuracy and comparability of the test results, this test sets a unified and strict aging condition. The aging temperature is set to 85℃, which can simulate the higher temperature environment that the material may face in the long-term use process, accelerate the change of the internal components of the material, and thus observe the change of the flame-retardant performance in a relatively short period of time. The humidity is controlled at 50% relative humidity, which is close to the environmental humidity in many actual application scenarios, and can better reflect the aging condition of the material in the general humidity environment. The aging time is set to 168h, which is long enough for the material to age to a certain extent under the set temperature and humidity conditions, and thus evaluate its flame-retardant durability. Under such clear and unified aging conditions, the test can more accurately judge the change of the flame-retardant performance of the polyurethane foam at different stages.

[0044] Table 3. Flame-retardant durability indicators of polyurethane foam

[0045] (3) Long-term heat resistance test The foam sample was placed in a 120±2℃ drying oven for 500h, and the compression strength retention rate (compression strength after heating / compression strength before heating x 100%) was tested before and after heating, and the results are shown in Table 4.

[0046] Table 4. Long-term heat resistance indicators of polyurethane foam

[0047] The result analysis shows that the comprehensive performance of examples 1-4 is significantly better than each of the comparative examples, which fully verifies the effectiveness of the technical scheme of the application. On the basis of the performance of polyether polyol, the hydroxyl value of the examples is stable at 381.9-382.6 mgKOH / g, and the functionality is 3.28-3.49, which meets the design expectation; the hydroxyl value of comparative example 2 is reduced to 361.8 mgKOH / g because the residual incomplete reaction of the starting agent exists; the viscosity of comparative example 3 reaches 19562 mPa·s and the functionality is 4.32 because the ratio of the starting agent exceeds the limit, and the performance is abnormal. In terms of the performance of polyurethane foam, the compressive strength of the examples is 252-258 kPa, the oxygen index is 32.8-33.5%, the thermal conductivity is 0.014-0.016 W / (m·K), the cell diameter is 52-62 μm, and each index is optimal. The oxygen index of comparative example 1 is reduced to 30.2% and the thermal conductivity is increased to 0.018 W / (m·K) because there is no synergistic additive; the oxygen index of comparative example 3 is only 25.8% because the ratio of the starting agent exceeds the limit; the strength retention rate of comparative example 5 is only 82.7% because the additive is not pretreated; the thermal conductivity of comparative example 6 reaches 0.020 W / (m·K) because there is no phosphorus-based starting agent. In terms of flame-retardant durability and long-term heat resistance, the oxygen index retention rate of the examples is 96.7-97.9% and the strength retention rate is 94.8-95.0%, which is much higher than that of each of the comparative examples (oxygen index retention rate 80.1-85.3%, strength retention rate 82.7-86.6%). In summary, the technical system of “ternary starting agent ratio + segmented temperature control + pretreatment of synergistic additive” of the application can effectively solve the defects of traditional polyether and achieve performance breakthrough.

Claims

1. A low thermal conductivity flame retardant polyether polyol characterized in that: A double (2-hydroxyethyl) aminomethyl phosphonic acid diethyl ester, a halogen-containing aniline and a small molecule alcohol / alcohol amine are used as a ternary mixed initiator, and under the action of a catalyst, polymerization is carried out with an alkylene oxide to obtain; The double (2-hydroxyethyl) aminomethyl phosphonic acid diethyl ester has the following structural formula: ； The halogen-containing aniline is one or more of 3,3'-dichloro-4,4'-diamino diphenyl methane, 4-chloro-4'-bromine diphenylamine, p-chloroaniline, 3,4-dichloroaniline, 2,5-dichloroaniline, 5-chloro-m-phenylenediamine, 4-chloro-o-phenylenediamine, p-bromoaniline, 4-bromo-2,6-dichloroaniline, 2,4-dibromoaniline, bis (4-bromophenyl) amine or 2,4-difluoroaniline; and the small molecule alcohol / alcohol amine is one or more of sorbitol, 1,4-butanediol, triethanolamine, diethylene glycol, glycerol, hexanediol or propylene glycol. The mass percentage of each component of the ternary mixed initiator in the mixed initiator is as follows: double (2-hydroxyethyl) aminomethyl phosphonic acid diethyl ester 12.15-22.78%, halogen-containing aniline 43.21-63.89%, and small molecule alcohol / alcohol amine 23.96-34.01%.

2. The low thermal conductivity flame retardant polyether polyol of claim 1, wherein: The catalyst is one or both of KOH and NaOH; and the addition amount of the catalyst is 0.21-0.39% of the total mass of the ternary mixed initiator, the alkylene oxide and the catalyst.

3. The low thermal conductivity flame retardant polyether polyol of claim 1, wherein: The alkylene oxide is one or both of propylene oxide and ethylene oxide; and the mass ratio of the alkylene oxide to the ternary mixed initiator is (1.04-1.33):

1.

4. A process for the preparation of a low thermal conductivity flame retardant polyether polyol according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: (1) double (2-hydroxyethyl) aminomethyl phosphonic acid diethyl ester, halogen-containing aniline, small molecule alcohol / alcohol amine and catalyst are put into a reaction kettle, the temperature is raised to 92-95 DEG C under a negative pressure atmosphere, the temperature is kept for 1-1.2 h, vacuum is drawn to -0.092 to -0.105 MPa, the temperature is raised to 96-100 DEG C, and part of the alkylene oxide is added dropwise for segmented temperature control chain extension; after the feeding is completed, the internal pressure reaction is continued for 1.6-2.2 h to obtain a polyether polyol intermediate; (2) the polyether polyol intermediate is heated to 118-138 DEG C, and the remaining alkylene oxide is added dropwise for end-capping synthesis; After the feeding is completed, the internal pressure reaction is continued for 2.2-3.2 h, the pressure is increased to 0.22-0.26 MPa by nitrogen gas, and the pressure is kept stable for more than 15 min without further reduction; nitrogen gas bubbling is used to remove residual small molecules to obtain a low thermal conductivity flame-retardant polyether polyol.

5. The process for the preparation of a low thermal conductivity flame retardant polyether polyol according to claim 4, characterized in that: In step (1), the addition amount of the alkylene oxide is 26.28-33.98% of the total mass of the alkylene oxide.

6. The method for preparing low thermal conductivity flame-retardant polyether polyol according to claim 4, characterized in that: In step (2), the temperature of nitrogen gas bubbling is 82-98 DEG C, and the pressure is -0.082 to -0.092 MPa.

7. Use of a low thermal conductivity flame retardant polyether polyol according to any one of claims 1 to 3, characterized in that: The method is used for preparing a rigid polyurethane foam.

8. Use of a low thermal conductivity flame retardant polyether polyol according to claim 7, characterized in that: A pretreated environmentally-friendly synergistic aid is added in the preparation of the rigid polyurethane foam, and a four-element synergistic system is formed with the phosphorus-nitrogen-halogen structure in the polyether polyol.

9. Use of a low thermal conductivity flame retardant polyether polyol according to claim 8, characterized in that: The pretreated environmentally-friendly synergistic aid is prepared by compounding one or both of nano magnesium hydroxide and montmorillonite and pretreating with a silane coupling agent, and the addition amount of the pretreated environmentally-friendly synergistic aid is 2.5-4.8% of the mass of the polyether polyol.

10. Use of a low thermal conductivity flame retardant polyether polyol according to claim 9, characterized in that: The mass ratio of the environment-friendly synergist to the silane coupling agent is (5.38-6.67):1, the pretreatment temperature is 85-95 DEG C, and the pretreatment time is 1.5-2h.

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