Low thermal conductivity flame retardant polyether polyol, method for preparing same, and use thereof

Abstract

The application belongs to the technical field of polyether polyols, and particularly relates to low-thermal-conductivity flame-retardant polyether polyols, a preparation method thereof and application thereof. The low-thermal-conductivity flame-retardant polyether polyols are obtained by polymerization of a diethyl bis(2-hydroxyethyl) aminomethyl phosphonate, a halogen-containing aniline and a small-molecule alcohol / alcohol amine as a ternary mixed initiator with an alkylene oxide under the action of a catalyst; the mass percentage of each component of the ternary mixed initiator in the mixed initiator is as follows: 12.15-22.78% of the diethyl bis(2-hydroxyethyl) aminomethyl phosphonate, 43.21-63.89% of the halogen-containing aniline and 23.96-34.01% of the small-molecule alcohol / alcohol amine. The polyether polyols achieve the comprehensive performance of 'flame-retardant durability, high strength and low thermal conductivity', and the application also provides a preparation method thereof and application thereof in rigid polyurethane foam.

Description

Technical Field

[0001] This invention belongs to the field of polyether polyol technology, specifically relating to a flame-retardant polyether polyol with low thermal conductivity, its preparation method, and its application. Background Technology

[0002] Polyether polyols, as the core raw material for synthesizing rigid polyurethane foam, have four major limitations in performance and processing of traditional products, making them difficult to adapt to the needs of modern high-end industries:

[0003] (1) The flame retardant system is simple and has poor durability: Traditional polyether relies on the physical addition of a single flame retardant (such as triphosphate TCEP), which is not only easy to migrate and lose over time, resulting in a decrease of more than 15% in flame retardant effect per year, but also requires a high amount of single halogen or phosphorus flame retardant to meet the standard, causing a decrease of about 30% in the mechanical properties of the material.

[0004] (2) Insufficient controllability of polymerization process: Traditional polymerization often adopts the "one-step heating" method, which directly raises the temperature to the reaction temperature and then starts to introduce PO. It does not activate the initiator by preparing potassium alkoxide at low temperature, which makes epoxides easy to react preferentially with small molecule alcohols / amines. This results in incomplete reaction of functional initiators (such as phosphorus compounds), high residual amount, and affects the overall performance stability of polyether.

[0005] (3) It is difficult to balance mechanical strength and thermal insulation performance: the cross-linking degree of traditional polyether molecular chains is not well controlled. The polyurethane foam produced has large and unevenly distributed pores. Either the compressive strength is less than 200 kPa, or the thermal conductivity is >0.025 W / (m·K), which cannot meet the requirements of high strength and low thermal conductivity at the same time.

[0006] (4) Lack of downstream foaming synergy: The existing scheme does not combine polyether modification with foaming agent design. The functional groups in 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.

[0007] Chinese Patent CN 113754877 A discloses a method for preparing a low thermal conductivity polyether polyol, comprising the following steps: (1) adding a fluorinated compound, an alcohol initiator, and solid KOH together into a reaction vessel, sealing it, purging with nitrogen to raise the temperature, and introducing propylene oxide; (2) controlling the temperature inside the reaction vessel at 80-120℃, continuously adding propylene oxide for the first time, controlling the material temperature at 80-120℃ during the reaction, and the pressure inside the vessel at 0.1-0.4MPa; (3) evacuating and raising the temperature to 100-150℃, continuously adding propylene oxide for the second time, controlling the temperature at 100-150℃ during the reaction, and the pressure inside the vessel at 0.1-0.4MPa; (4) removing unreacted monomers; (5) post-processing to obtain the polyether polyol product. The rigid polyurethane foam prepared using the low thermal conductivity polyether polyol has the characteristics of high activity, low thermal conductivity, and good demolding properties. However, while the polyether polyols prepared by this method improve these properties of rigid polyurethane foam, their effect on improving other key properties of foam plastics, such as mechanical strength and flame retardancy, is not significant enough, and there is still room for further optimization in terms of thermal conductivity.

[0008] Chinese patent CN 116948163 A discloses a halogen-free flame-retardant polyether polyol containing dihydroxy DOPO, its preparation method, and its applications. The halogen-free flame-retardant polyether polyol containing dihydroxy DOPO is obtained by polymerizing dihydroxy DOPO and a polyol as mixed initiators with an epoxide alkane under the action of a composite catalyst. The mass percentage of dihydroxy DOPO in the mixed initiator is 35-62%. The prepared halogen-free flame-retardant polyether polyol containing dihydroxy DOPO, by introducing a ternary phenanthrene ring structure from DOPO, exhibits better mechanical strength, activity, and flame-retardant properties compared to other polyether polyols when used in polyurethane materials. However, to better meet increasingly stringent requirements, there is still room for improvement in its mechanical strength, flame-retardant properties, and thermal conductivity. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a flame-retardant polyether polyol with low thermal conductivity, which achieves comprehensive performance of "long-lasting flame retardancy, high strength and low thermal conductivity". The present invention also provides its preparation method and its application in rigid polyurethane foam products.

[0010] The low thermal conductivity flame-retardant polyether polyol of the present invention is obtained by polymerizing bis(2-hydroxyethyl)aminomethylphosphonic acid diethyl ester, halogenated aniline and small molecule alcohol / alkanolamine as ternary mixed initiators with epoxy alkane under the action of a catalyst.

[0011] The structural formula of the diethyl bis(2-hydroxyethyl)aminomethylphosphonate is as follows:

[0012] .

[0013] Diethyl bis(2-hydroxyethyl)aminomethylphosphonic acid: It contains a unique phosphorus-nitrogen synergistic structure. On the one hand, the phosphorus element forms a phosphate ester flame retardant coating during combustion, which isolates oxygen and heat. On the other hand, the nitrogen element can react with halogens to generate halogenated amine compounds, which enhances the flame retardant effect. At the same time, its hydroxyl group can fully react with epoxy alkanes, avoiding the problem of easy migration of traditional phosphorus-based flame retardants.

[0014] The halogenated aniline is one or more of the following: 3,3'-dichloro-4,4'-diaminodiphenylmethane, 4-chloro-4'-bromodiphenylamine, 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 halogenated aniline provides the halogen element, forming a phosphorus-nitrogen-halogen ternary synergistic flame retardant with the phosphorus-nitrogen structure of diethyl bis(2-hydroxyethyl)aminomethylphosphonate. Furthermore, the benzene ring structure enhances the rigidity of the polyether molecular chain, improving the mechanical strength of the foam.

[0015] The small molecule alcohol / amine is one or more of sorbitol, 1,4-butanediol, triethanolamine, diethylene glycol, glycerol, hexanediol, or propylene glycol. The small molecule alcohol / amine provides multiple hydroxyl sites, regulating the degree of polyether crosslinking and resulting in finer foam cells; simultaneously, its moderate hydroxyl activity allows for orderly reaction with other initiators and epoxy alkane, avoiding component residues during polymerization.

[0016] The mass percentages of each component in the ternary mixed initiator are as follows: diethyl bis(2-hydroxyethyl)aminomethylphosphonate 12.15-22.78%, halogenated aniline 43.21-63.89%, and small molecule 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 deteriorate simultaneously.

[0017] Preferably, the catalyst is one or both of KOH and NaOH, which have stable catalytic activity and can precisely control the ring-opening polymerization rate of alkyl epoxides, avoiding local overheating caused by excessively fast reaction; the amount of catalyst added is 0.21-0.39% of the total mass of the ternary mixed initiator, alkyl epoxides and catalyst.

[0018] Preferably, the epoxy alkane is one or both of propylene oxide and ethylene oxide. Propylene oxide provides flexibility to the polyether molecular chain, while ethylene oxide enhances the activity of hydroxyl groups. The combination of the two can balance the viscosity and reactivity of the polyether. The mass ratio of epoxy alkane to ternary mixed initiator is (1.04-1.33):1.

[0019] The preparation method of low thermal conductivity flame-retardant polyether polyols described in this invention is based on a "low-temperature segmented temperature-controlled chain extension-high-temperature precise end-capping" process, which includes the following steps:

[0020] (1) Segmented temperature-controlled chain extension stage: Diethyl bis(2-hydroxyethyl)aminomethylphosphonic acid, halogenated aniline, small molecule alcohol / alkanolamine and catalyst are added to the reactor. The reactor is pressurized to 0.25-0.28 MPa and leak tested for 35 min to ensure the reactor is sealed. The temperature is raised to 92-95℃ under negative pressure and kept at that temperature for 1-1.2 h to preliminarily activate the small molecule alcohol / alkanolamine. The vacuum is evacuated to -0.092 to -0.105 MPa and the temperature is raised to 96-100℃. A portion of epoxy alkane is added dropwise for segmented temperature-controlled chain extension. After the feed is completed, the internal pressure reaction continues for 1.6-2.2 h to obtain the polyether polyol intermediate. In this stage, segmented temperature control avoids the preferential reaction between epoxy alkane and small molecule alcohol / alkanolamine, ensuring that diethyl bis(2-hydroxyethyl)aminomethylphosphonic acid and halogenated aniline fully participate in the polymerization and reducing the residual amount of initiator.

[0021] (2) High-temperature precise end-capping and purification stage: The polyether polyol intermediate is heated to 118-138℃, and the remaining epoxy alkane is added dropwise for precise end-capping synthesis; after the feeding is completed, the internal pressure reaction continues for 2.2-3.2h, and nitrogen gas is introduced to pressurize to 0.22-0.26MPa and the pressure is stable for more than 15min without decreasing, indicating that the reaction is complete; the temperature is lowered and nitrogen gas is bubbled for 0.35-0.55h to remove residual small molecules; after the bubbling is completed, the temperature is lowered to 72-92℃ to release the material, and flame-retardant polyether polyol with low thermal conductivity is obtained.

[0022] In step (1), the amount of alkyl epoxide added is 26.28-33.98% of the total mass of alkyl epoxide.

[0023] In step (1), the polymerization process adopts the "segmented temperature-controlled chain extension" process. The temperature of the chain extension stage is controlled in two stages: the temperature of the first stage is 92-95℃ and the holding time is 1-1.2h; the temperature of the second stage is 96-100℃ and the holding time is 1.6-2.2h, so as to avoid preferential reaction between epoxide alkanes and small molecule alcohols / alkanolamines, resulting in initiator residue.

[0024] In step (2), the temperature of nitrogen bubbling is 82-98℃ and the pressure is -0.082 to -0.092MPa.

[0025] The application of the low thermal conductivity flame-retardant polyether polyol described in this invention is used to prepare rigid polyurethane foam.

[0026] In the preparation of rigid polyurethane foam, environmentally friendly pretreatment synergists need to be added to form a quaternary synergistic system with the phosphorus-nitrogen-halogen structure in polyether polyol.

[0027] The pretreated environmentally friendly synergist is prepared by compounding one or two of nano-magnesium hydroxide and montmorillonite with a silane coupling agent (KH-550 or KH-560). The amount of the pretreated environmentally friendly synergist added is 2.5-4.8% of the mass of the polyether polyol.

[0028] Nano-magnesium hydroxide and montmorillonite are selected as environmentally friendly synergistic additives. Nano-magnesium hydroxide releases moisture and cools the air during combustion, while montmorillonite forms a layered barrier structure. The environmentally friendly synergistic additives require pretreatment with a silane coupling agent (KH-550 / KH-560). The mass ratio of the environmentally friendly synergistic additive to the silane coupling agent is (5.38-6.67):1. The pretreatment temperature is 85-95℃, and the time is 1.5-2 hours. The amino / epoxy groups of the coupling agent react with the hydroxyl groups on the surface of the additive, improving the compatibility between the additive and the polyether polyol and preventing additive agglomeration that could lead to a decrease in foam performance.

[0029] The preparation process of the rigid polyurethane foam is as follows:

[0030] Component A is prepared by mixing 100 parts of polyether polyol, pretreated environmentally friendly synergist (addition amount is 2.5-4.8% of the mass of polyether polyol), flame retardant (TCEP), catalyst (MAYCAT PC8), water, and physical foaming agent (cyclopentane); Component B is PM200 from Wanhua Chemical Group Co., Ltd.; Component A and Component B are mixed and foamed according to an -NCO index of 1.05, and after curing, rigid polyurethane foam is obtained.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] (1) This invention is the first to construct a complete chain technology system of "optimized initiator ratio + temperature control of polymerization process + synergistic foaming agent", breaking through the limitations of traditional modification that only focuses on a single link. By fixing the ratio of ternary initiators, combined with environmentally friendly synergistic agents for segmented temperature control polymerization and pretreatment, the four-element synergistic flame retardancy of "phosphorus-nitrogen-halogen-inorganic" is achieved, solving the triple problem of "easy flame retardancy decay, insufficient strength and high thermal conductivity" of traditional polyethers. The foam oxygen index is ≥32.8%, the compressive strength is ≥252kPa, and the thermal conductivity is ≤0.016W / (m·K). It is especially suitable for scenarios with strict requirements for the comprehensive performance of materials such as building exterior wall insulation, cold chain vehicle insulation, and electronic component packaging, which have strict requirements for the comprehensive performance of materials such as "flame retardant durability-high mechanical strength-low thermal conductivity".

[0033] (2) The present invention adopts the process of “low temperature segmented temperature control chain expansion + high temperature precision end sealing”. By segmented temperature control, the high-activity initiator is prevented from reacting preferentially, resulting in residual initiator, and the performance stability is significantly improved.

[0034] (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.

[0035] (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

[0036] 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.

[0037] The following describes some of the raw materials used in the examples and comparative examples:

[0038] Diethyl bis(2-hydroxyethyl)aminomethylphosphonic acid (Shanghai Aladdin Biochemical Technology Co., Ltd., purity 99.2%).

[0039] Halogenated aniline (Sinopharm Chemical Reagent Co., Ltd., industrial grade);

[0040] Small molecule alcohols / amines (Tianjin Kemio Chemical Reagent Co., Ltd., industrial grade);

[0041] Catalyst (KOH / NaOH, analytical grade, Tianjin Damao Chemical Reagent Factory);

[0042] Epoxyalkanes (propylene oxide / ethylene oxide, 99.5% purity, Wanhua Chemical Group Co., Ltd.);

[0043] 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.).

[0044] Silane coupling agent (KH-550 / KH-560, analytical grade, Nanjing Shuguang Chemical Group Co., Ltd.).

[0045] Example 1

[0046] (1) Pretreatment of environmentally friendly synergistic additives

[0047] 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;

[0048] (2) Preparation of polyether polyols

[0049] 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;

[0050] 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;

[0051] (3) Preparation of rigid polyurethane foam

[0052] 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.

[0053] Example 2

[0054] (1) Pretreatment of environmentally friendly synergistic additives

[0055] 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.

[0056] (2) Preparation of polyether polyols

[0057] 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;

[0058] 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;

[0059] (3) Preparation of rigid polyurethane foam

[0060] The raw materials were mixed to prepare component A (100 parts polyether polyol, 2.5 parts pretreated montmorillonite, 18 parts TCEP, 1.0 parts MAYCATPC8, 0.65 parts water, and 22 parts 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.

[0061] Example 3

[0062] (1) Pretreatment of environmentally friendly synergistic additives

[0063] 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 to obtain compound pretreatment aid, and dry it for later use.

[0064] (2) Preparation of polyether polyols

[0065] Segmented temperature-controlled chain extension stage: 520.0g of 2,4-dibromoaniline, 180.0g of diethyl bis(2-hydroxyethyl)aminomethylphosphonic acid, 300.0g 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 35min; 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;

[0066] 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;

[0067] (3) Preparation of rigid polyurethane foam

[0068] 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.

[0069] Example 4

[0070] (1) Pretreatment of environmentally friendly synergistic additives

[0071] Take 28g of nano magnesium hydroxide, add 5.2g of silane coupling agent KH-550, stir and pretreat at 88℃ for 1.6h to obtain pretreated nano magnesium hydroxide, dry and set aside for later use;

[0072] (2) Preparation of polyether polyols

[0073] Segmented temperature-controlled chain extension stage: 580.0g of 3,3'-dichloro-4,4'-diaminodiphenylmethane, 160.0g of diethyl bis(2-hydroxyethyl)aminomethylphosphonic acid, 260.0g of triethanolamine and 7.8g of NaOH were added to the reactor; the pressure was increased to 0.27MPa and a leak test was performed for 35min; the temperature was raised to 93℃ under negative pressure and held for 1.05h; the pressure was then further reduced to -0.095MPa and the temperature was raised to 97℃; 393g of ethylene oxide (accounting for 31.90% of the total ethylene oxide mass) was added dropwise; after the feeding was completed, the reaction was carried out under internal pressure for 1.8h to obtain the polyether polyol intermediate;

[0074] High-temperature precision end-capping and purification stage: The intermediate was heated to 130℃ and 839g of propylene oxide was added dropwise; after the feeding was completed, the temperature was maintained and the reaction continued for 2.5h; nitrogen was purged to 0.25MPa, and after the pressure was stabilized for 15min, the temperature was lowered to 95℃; nitrogen was bubbled at -0.085MPa for 0.4h; the temperature was lowered to 88℃ and the material was discharged to obtain flame-retardant polyether polyol with low thermal conductivity;

[0075] (3) Preparation of rigid polyurethane foam

[0076] 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.

[0077] Comparative Example 1

[0078] The preparation process of polyether polyol is the same as in Example 3; no pretreatment synergist is added during foam preparation, and the remaining ingredients and processes are the same as in Example 3.

[0079] Comparative Example 2

[0080] During the preparation of polyether polyol, the chain extension stage is directly heated to 98°C and held for 2.1 hours (without segmentation). The remaining processes and foam preparation are the same as in Example 3.

[0081] Comparative Example 3

[0082] (1) Pretreatment of environmentally friendly synergistic additives

[0083] 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;

[0084] (2) Preparation of polyether polyols

[0085] Segmented temperature-controlled chain extension stage: 400.0g of 2,4-dibromoaniline, 100.0g of diethyl bis(2-hydroxyethyl)aminomethylphosphonic acid, 500.0g 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 35min; the reactor was heated to 94℃ under negative pressure and held for 1.1h; the reactor was then evacuated to -0.10MPa and heated to 98℃; 379g of ethylene oxide (accounting for 19.01% of the total alkylene oxide mass) was added dropwise; after the feed was completed, the reactor was subjected to internal pressure reaction for 2.0h to obtain a polyether polyol intermediate.

[0086] High-temperature precision 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 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;

[0087] (3) Preparation of rigid polyurethane foam

[0088] 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.

[0089] Comparative Example 4

[0090] (1) Pretreatment of environmentally friendly synergistic additives

[0091] Take 28g of nano magnesium hydroxide, add 5.2g of silane coupling agent KH-550, stir and pretreat at 88℃ for 1.6h, and dry for later use;

[0092] (2) Preparation of polyether polyols

[0093] Segmented temperature-controlled chain extension stage: 700.0g of 3,3'-dichloro-4,4'-diaminodiphenylmethane, 250.0g of diethyl bis(2-hydroxyethyl)aminomethylphosphonic acid, 50.0g of triethanolamine and 7.8g of NaOH were added to the reactor; the pressure was increased to 0.27MPa and a leak test was performed for 35min; the temperature was raised to 93℃ under negative pressure and held for 1.05h; the pressure was then further reduced to -0.095MPa and the temperature was raised to 97℃; 393g of ethylene oxide (accounting for 40.23% of the total alkylene oxide mass) was added dropwise; after the feeding was completed, the reaction was carried out under internal pressure for 1.8h to obtain the polyether polyol intermediate;

[0094] High-temperature precision end-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 and the reaction continued for 2.5h; nitrogen was purged to 0.25MPa, and after the pressure was stabilized for 15min, the temperature was lowered to 95℃; nitrogen was bubbled at -0.085MPa for 0.4h; the temperature was lowered to 88℃ and the material was discharged to obtain flame-retardant polyether polyol with low thermal conductivity;

[0095] (3) Preparation of rigid polyurethane foam

[0096] 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.

[0097] Comparative Example 5

[0098] 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.

[0099] Comparative Example 6

[0100] (1) Pretreatment of environmentally friendly synergistic additives

[0101] 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;

[0102] (2) Preparation of polyether polyols

[0103] 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;

[0104] 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;

[0105] (3) Preparation of rigid polyurethane foam

[0106] 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.

[0107] Performance testing

[0108] 1. Basic performance testing of polyether polyols

[0109] The properties of the polyether polyols in Examples 1-4 and Comparative Examples 1-6 were tested according 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.

[0110] Table 1 Basic Performance Indicators of Polyether Polyols

[0111]

[0112] 2. Performance testing of rigid polyurethane foam

[0113] (1) Routine performance testing

[0114] The conventional properties of polyurethane foam were tested in accordance with 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.

[0115] Table 2. Conventional performance indicators of polyurethane foam

[0116]

[0117] (2) Flame retardancy durability test of polyurethane foam

[0118] To ensure the accuracy and comparability of test results, uniform and stringent aging conditions were established for this test. The aging temperature was set at 85℃, which simulates the high temperature environment that materials may face during long-term use, accelerating changes in the internal composition of the material and allowing for observation of changes in flame-retardant properties within a relatively short period. Humidity was controlled at 50% relative humidity, a condition close to the environmental humidity in many practical application scenarios, effectively reflecting the aging of materials under typical humidity conditions. The aging time was set at 168 hours, sufficient to allow the material to age to a certain extent under the specified temperature and humidity conditions, thereby assessing its flame-retardant durability. Testing under such clearly defined and uniform aging conditions allows for a more accurate assessment of the changes in the flame-retardant properties of polyurethane foam at different stages.

[0119] Table 3 Flame Retardant Durability Indicators of Polyurethane Foam

[0120]

[0121] (3) Long-term heat resistance test

[0122] The foam samples were placed in a drying oven at 120±2℃ for 500 hours, and the retention rate of compressive strength before and after heating was tested (compressive strength after heating / compressive strength before heating × 100%). The results are shown in Table 4.

[0123] Table 4. Long-term heat resistance index of polyurethane foam

[0124]

[0125] The results analysis showed that the overall performance of Examples 1-4 was significantly better than that of the comparative examples, fully verifying the effectiveness of the technical solution of the present invention. Regarding the basic properties of the polyether polyol, the hydroxyl value of the examples was stable at 381.9-382.6 mgKOH / g, and the functionality was 3.28-3.49, meeting the design expectations. Comparative Example 2, due to the lack of segmented temperature control, had a hydroxyl value reduced to 361.8 mgKOH / g because the initiator reaction was incomplete and residual. Comparative Example 3, due to an excessive initiator ratio, had a viscosity of 19562 mPa·s and a functionality of 4.32, exhibiting abnormal performance. In terms of polyurethane foam performance, the examples showed the best performance in terms of compressive strength (252-258 kPa), oxygen index (32.8-33.5%), thermal conductivity (0.014-0.016 W / (m·K)), and cell diameter (52-62 μm). Comparative Example 1, without synergistic additives, showed an oxygen index reduced to 30.2% and a thermal conductivity increased to 0.018 W / (m·K); Comparative Example 3, with an excessive initiator ratio, had an oxygen index of only 25.8%; Comparative Example 5, without pretreatment of additives, had a strength retention rate of only 82.7%; Comparative Example 6, without phosphorus-based initiators, achieved a thermal conductivity of 0.020 W / (m·K). Regarding flame retardancy and long-term heat resistance, the examples showed an oxygen index retention rate of 96.7-97.9% and a strength retention rate of 94.8-95.0%, significantly higher than the comparative examples (oxygen index retention rate 80.1-85.3%, strength retention rate 82.7-86.6%). In summary, the "ternary initiator ratio + segmented temperature control + pretreatment synergistic additive" technical system of this invention can effectively solve the defects of traditional polyethers and achieve a performance breakthrough.

Claims

1. An application of a flame-retardant polyether polyol with low thermal conductivity, characterized in that: Used to prepare rigid polyurethane foam; during the preparation of rigid polyurethane foam, pre-treated environmentally friendly synergistic additives need to be added to form a quaternary synergistic system with the phosphorus-nitrogen-halogen structure in polyether polyol; The environmentally friendly synergistic agent for pretreatment is prepared by a combination of one or two of nano-magnesium hydroxide and montmorillonite, and pretreated with a silane coupling agent. The low thermal conductivity flame-retardant polyether polyol is obtained by polymerizing bis(2-hydroxyethyl)aminomethylphosphonic acid diethyl ester, halogenated aniline and small molecule alcohol / alkanolamine as ternary mixed initiators with epoxy alkane under the action of a catalyst. The structural formula of the diethyl bis(2-hydroxyethyl)aminomethylphosphonate is as follows: ； The halogenated aniline is one or more of 3,3'-dichloro-4,4'-diaminodiphenylmethane, 4-chloro-4'-bromodiphenylamine, 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 small molecule alcohol / amine is one or more of sorbitol, 1,4-butanediol, triethanolamine, diethylene glycol, glycerol, hexanediol, or propylene glycol. The mass percentages of each component in the ternary mixed initiator are as follows: diethyl bis(2-hydroxyethyl)aminomethylphosphonate 12.15-22.78%, halogenated aniline 43.21-63.89%, and small molecule alcohol / amine 23.96-34.01%; The preparation method of the low thermal conductivity flame-retardant polyether polyol includes the following steps: (1) Add diethyl bis(2-hydroxyethyl)aminomethylphosphonic acid, halogenated aniline, small molecule alcohol / alkanolamine and catalyst to the reactor, heat to 92-95℃ under negative pressure atmosphere, keep at temperature for 1-1.2h, evacuate to -0.092 to -0.105MPa, heat to 96-100℃, add some epoxy alkane dropwise for segmented temperature-controlled chain extension; after the feeding is completed, continue the internal pressure reaction for 1.6-2.2h to obtain polyether polyol intermediate; (2) Heat the polyether polyol intermediate to 118-138℃ and add the remaining epoxy alkane dropwise for end-capping synthesis; After feeding is complete, continue the internal pressure reaction for 2.2-3.2 hours, pressurize with nitrogen to 0.22-0.26 MPa and keep the pressure stable for more than 15 minutes without decreasing; remove residual small molecules by bubbling with nitrogen to obtain flame-retardant polyether polyol with low thermal conductivity.

2. The application of the low thermal conductivity flame-retardant polyether polyol according to claim 1, characterized in that: The catalyst is one or both of KOH and NaOH; the amount of catalyst added is 0.21-0.39% of the total mass of the ternary mixed initiator, epoxide, and catalyst.

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

1.

4. The application of the low thermal conductivity flame-retardant polyether polyol according to claim 1, characterized in that: In step (1), the amount of alkyl epoxide added is 26.28-33.98% of the total mass of alkyl epoxide.

5. The application of the low thermal conductivity flame-retardant polyether polyol according to claim 1, characterized in that: In step (2), the temperature of nitrogen bubbling is 82-98℃ and the pressure is -0.082 to -0.092MPa.

6. The application of the low thermal conductivity flame-retardant polyether polyol according to claim 1, characterized in that: The amount of the environmentally friendly synergistic additive added during the pretreatment is 2.5-4.8% of the mass of the polyether polyol.

7. The application of the low thermal conductivity flame-retardant polyether polyol according to claim 6, characterized in that: The mass ratio of the environmentally friendly synergist 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.

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