Polymeric phosphine-containing polyol as well as preparation method and application thereof

Abstract

The invention discloses polymeric phosphine-containing polyol as well as a preparation method and application thereof, relates to the field of flame retardance of rigid foaming polyurethane thermal insulation materials, and aims to solve the problems that a flame retardant is easy to migrate, the durability is poor and the mechanical property is obviously reduced in the conventional flame-retardant polyurethane material. The polymeric phosphine-containing polyol is hydroxymethyl polyethylene glycol phosphonate, and the method comprises the following steps: 1, adding diethyl phosphite and a catalyst into a reaction device, dropwise adding ethylene glycol into a reaction system, carrying out a heating reaction, filtering, and washing to obtain polyethylene glycol phosphate; and 2, adding the polyethylene glycol phosphate and a catalyst into a reaction device, adding paraformaldehyde, heating for reaction, filtering and washing to obtain the hydroxymethyl polyethylene glycol phosphate. By replacing a certain proportion of polyether polyol and introducing HMGP into a polyurethane molecular chain segment, the intrinsic flame-retardant RPUF material is prepared, and the material is endowed with excellent flame retardance and aging resistance. The preparation method is used for preparing the durable flame-retardant and aging-resistant RPUF material.

Description

Technical Field

[0001] The invention relates to the field of flame retardant rigid foamed polyurethane thermal insulation materials, and in particular to a polymerized phosphine-containing polyol and a preparation method and application thereof. Background Art

[0002] Rigid polyurethane foam (RPUF) is made of isocyanate and polyol as the main raw materials, with the help of various additives such as foaming agent and catalyst. It has the advantages of light weight, high specific strength and heat insulation, and is widely used in building exterior wall insulation and heat insulation. However, RPUF material has a large specific surface area and is very easy to burn, which seriously threatens people's lives and property safety. Therefore, it is necessary to modify the RPUF material to be flame retardant.

[0003] At present, the flame retardant modification of RPUF thermal insulation materials is mainly achieved by directly adding flame retardants during the foaming process. This method is simple in process, but has the disadvantages of large amount of flame retardants added, easy precipitation, affecting the mechanical properties and thermal insulation properties of the material, and failing to achieve durable flame retardancy of RPUF materials. In addition, by modifying the surface of RPUF materials with flame retardant coatings, the materials can maintain good mechanical and thermal insulation properties, but the coatings have poor weather resistance and are easy to fall off under external forces, affecting the durable flame retardancy of the materials. Summary of the invention

[0004] The present invention aims to solve the problems of easy migration of flame retardants, poor durability and obvious reduction in mechanical properties of existing flame retardant polyurethane materials, and provides a polymerized phosphine-containing polyol and a preparation method and application thereof.

[0005] The polymeric phosphine-containing polyol of the present invention is hydroxymethyl polyethylene glycol phosphonate (HMGP), and its chemical structural formula is:

[0006]

[0007] The method for preparing the above-mentioned polymeric phosphine-containing polyol comprises the following steps:

[0008] 1. Under anhydrous and oxygen-free reaction conditions, diethyl phosphite and catalyst 1 are added to a reaction device, and the mixture is heated to 120-130° C. by a constant temperature oil bath heating device under stirring, and then ethylene glycol is added dropwise to the reaction system. After the dropwise addition is completed, the system is heated to 140-160° C. and reacted for 6-8 hours. No more methanol is produced, and a filtering device is used for filtering. The product is fully washed with n-hexane to obtain an intermediate polyethylene glycol phosphate;

[0009] 2. Add the prepared polyethylene glycol phosphate and catalyst 2 into a reaction device, add paraformaldehyde into the reaction system under stirring at room temperature, heat to 70-90° C., react for 4-6 hours, filter and wash after cooling to obtain hydroxymethyl polyethylene glycol phosphonate (HMGP).

[0010] Furthermore, in step 1, the mass ratio of ethylene glycol to diethyl phosphite is 1:(1.8-2).

[0011] Furthermore, in step 1, the catalyst 1 is one or a mixture of titanium oxide, zinc oxide, iron oxide, magnesium oxide, and aluminum oxide, and the catalyst 1 accounts for 0.5% to 1% of the total mass of the reactants.

[0012] Furthermore, in step 2, the mass ratio of paraformaldehyde to polyethylene glycol phosphate is 1:(5.5-6).

[0013] Furthermore, in step 2, the catalyst 2 is one or a mixture of sodium hydroxide, potassium carbonate, potassium hydroxide, and the catalyst 2 accounts for 8% to 10% of the total mass of the reactants.

[0014] Furthermore, the heating rate in step 2 is 2-3°C / min.

[0015] The invention discloses an application of the polymerized phosphine-containing polyol in flame-retardant modified rigid foamed polyurethane thermal insulation material.

[0016] Furthermore, the specific preparation method of the rigid foamed polyurethane is:

[0017] The polyol, foam stabilizer, n-hexane, triethylamine, dibutyltin dilaurate and deionized water are mixed and stirred to obtain a mixture; the mixture is added to polymethylene polyphenyl isocyanate (PM-200), foamed and cured to prepare a rigid foamed polyurethane. The polyol is a mixture of polymeric phosphine-containing polyol and polyether polyol, and the content of polymeric phosphine-containing polyol in the polyol is a, 0<a≤15%.

[0018] Furthermore, the ratio of polymethylene polyphenyl isocyanate to polyether polyol is (1.1-1.4): (1-1.2) according to the molar ratio of -NCO to -OH.

[0019] Beneficial effects of the present invention:

[0020] The polymeric phosphine-containing polyol of the present invention contains both PC and PO bond structures, and also contains a large number of -OH reactive groups, which are introduced into the molecular chain segments of polyurethane through the reaction of hydroxyl groups and isocyanate, and have little effect on the mechanical properties and thermal insulation properties of the material, and can be well maintained. At the same time, the flame retardant will not migrate and precipitate during use, and the material can achieve long-term flame retardancy. At the same time, the synergistic flame retardant effect of the condensed phase and the gas phase can be exerted to prepare an intrinsic, efficient, and long-term flame-retardant polyurethane thermal insulation material, which also has excellent mechanical properties, thermal insulation and weather resistance.

[0021] Compared with existing phosphorus-based flame retardants, it has higher flame retardant efficiency. When the replacement amount of HMGP is only 15wt%, the limiting oxygen index (LOI) value of RPUF material increases from 19.0% to 24.2%, and the vertical combustion (UL-94) test passes the V-0 level. At the same time, the flame retardant HMGP has little effect on the compressive strength and thermal insulation performance of RPUF materials, the pore morphology remains basically the same, and it has good heat aging resistance.

[0022] Compared with the prior art, the polymeric phosphine-containing polyol (HMGP) of the present invention does not use any toxic or hazardous raw materials during the synthesis process, has mild reaction conditions, safe operation, and high synthesis efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 FTIR images of DHPP and HMGP;

[0024] Figure 2 For DHPP and HMGP 1 H NMR spectra;

[0025] Figure 3 For DHPP and HMGP 31 P NMR spectra;

[0026] Figure 4 Screenshot of the vertical combustion test process. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any combination of the specific implementation modes.

[0028] Specific implementation method 1: In this implementation method, the polymeric phosphine-containing polyol is hydroxymethyl polyethylene glycol phosphonate (HMGP), and its chemical structural formula is:

[0029]

[0030] Phosphine-containing polyols react with isocyanates through their own alcohol hydroxyl groups to introduce flame-retardant monomers into the polyurethane molecular segments, which can not only maintain the mechanical and thermal insulation properties of the material, but also achieve long-lasting flame retardancy of the material. Most of the phosphorus-containing polyols currently used are phosphate ester structures, which mainly play a condensed phase flame retardant role through catalytic carbonization, but are easily hydrolyzed under humid conditions. Polymerized phosphine-containing polyols with PC bond structures have good heat resistance, hydrolysis resistance, and multiphase synergistic and efficient flame retardant effects of the condensed phase and the gas phase, which can give the material efficient flame retardancy, good mechanical and thermal insulation properties, and heat aging resistance.

[0031] Specific implementation method 2: The preparation method of the polymeric phosphine-containing polyol in this implementation method comprises the following steps:

[0032] 1. Under anhydrous and oxygen-free reaction conditions, diethyl phosphite and catalyst 1 are added to a reaction device, and the mixture is heated to 120-130° C. by a constant temperature oil bath heating device under stirring, and then ethylene glycol is added dropwise to the reaction system. After the dropwise addition is completed, the system is heated to 140-160° C. and reacted for 6-8 hours. No more methanol is produced, and a filtering device is used for filtering. The product is fully washed with n-hexane to obtain an intermediate polyethylene glycol phosphate;

[0033] 2. Add the prepared polyethylene glycol phosphate and catalyst 2 into a reaction device, add paraformaldehyde into the reaction system under stirring at room temperature, heat to 70-90° C., react for 4-6 hours, filter and wash after cooling to obtain hydroxymethyl polyethylene glycol phosphonate (HMGP).

[0034] The present invention uses diethyl phosphite containing a PH bond structure as a starting material, firstly undergoes a nucleophilic substitution reaction with ethylene glycol through an ester exchange reaction to generate polyethylene glycol phosphate; then undergoes a phosphine hydrogenation reaction with C=O in paraformaldehyde through the PH bond to generate a hydroxymethyl group and introduce it into the molecular structure of the flame retardant. The generated hydroxyl group can react with groups such as isocyanate, thereby introducing the synthesized flame retardant into the molecular chain segment of the polymer to achieve durable flame retardancy of the material. The reaction principle is as follows:

[0035]

[0036] Specific implementation method 3: In step 1 of this implementation method, the mass ratio of ethylene glycol to diethyl phosphite is 1:(1.8-2). Other steps and parameters are the same as those in specific implementation method 2.

[0037] Specific embodiment 4: The catalyst 1 in step 1 of this embodiment is one or a mixture of titanium oxide, zinc oxide, iron oxide, magnesium oxide, aluminum oxide, and the catalyst 1 accounts for 0.5% to 1% of the total mass of the reactants. Other steps and parameters are the same as those of specific embodiment 2 or 3.

[0038] Specific implementation method 5: In step 2 of this implementation method, the mass ratio of paraformaldehyde to polyethylene glycol phosphate is 1:(5.5-6). Other steps and parameters are the same as those of specific implementation methods 2 to 4.

[0039] Specific implementation example 6: The catalyst 2 in step 2 of this implementation example is one or a mixture of sodium hydroxide, potassium carbonate, potassium hydroxide, and the catalyst 2 accounts for 8% to 10% of the total mass of the reactants. Other steps and parameters are the same as those in specific implementation examples 2 to 5.

[0040] Specific implementation method 7: The heating rate in step 2 of this implementation method is 2-3°C / min. Other steps and parameters are the same as those in specific implementation methods 2 to 6.

[0041] Specific implementation method eight: the application of the polymerized phosphine-containing polyol in the flame-retardant modified rigid foamed polyurethane thermal insulation material according to the present implementation method.

[0042] Specific embodiment 9: The specific preparation method of the rigid foamed polyurethane described in this embodiment is:

[0043] The polyol, foam stabilizer, n-hexane, triethylamine, dibutyltin dilaurate and deionized water are mixed and stirred to obtain a mixture; the mixture is added to polymethylene polyphenyl isocyanate (PM-200), foamed and cured to prepare a rigid foamed polyurethane. The polyol is a mixture of polymeric phosphine-containing polyol and polyether polyol, and the content of polymeric phosphine-containing polyol in the polyol is a, 0<a≤15%. The other steps and parameters are the same as those in the eighth embodiment.

[0044] Specific embodiment 10: In this embodiment, the ratio of polymethylene polyphenyl isocyanate to polyether polyol is (1.1-1.4): (1-1.2) according to the molar ratio of -NCO to -OH. Other steps and parameters are the same as those of specific embodiment 9.

[0045] The embodiments of the present invention are described in detail below. The following embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation schemes and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0046] Embodiment 1:

[0047] Step 1: Synthesis of intermediate polyethylene glycol phosphate

[0048] First, diethyl phosphite and polyethylene glycol are subjected to an ester exchange reaction. 138.35 g of diethyl phosphite and 1.86 g of an aluminum oxide catalyst are added to a round-bottom flask equipped with a mechanical stirrer, a thermometer, a byproduct receiving device, a condenser and a dropping funnel. Nitrogen is introduced into the reaction device, and a liquid seal device is used to ensure that the reaction system is dry and oxygen-free. Then, the mixture in the round-bottom flask is heated to 130°C with an oil bath device, and then 74.8 g of ethylene glycol is slowly added dropwise to the reaction system. After the addition is completed, the temperature is raised to 160°C for reaction, and the reaction is terminated when no methanol is produced. The catalyst is removed by a filtering device, and then the product is fully washed with n-hexane to obtain an intermediate polyethylene glycol phosphonate.

[0049] Step 2: Synthesis of the product hydroxymethyl polyethylene glycol phosphonate (HMGP)

[0050] 101.00 g of polyethylene glycol phosphonate and 13.82 g of potassium carbonate catalyst were added to a round-bottom flask equipped with a reflux condenser, a thermometer and a mechanical stirrer, and 17.10 g of paraformaldehyde was added to the reaction system, and the temperature was gradually raised to 80° C. and maintained for 5.5 h under stirring. The catalyst was filtered off, and the product was washed several times to obtain a viscous liquid product, hydroxymethyl polyethylene glycol phosphonate (HMGP).

[0051] The hydroxymethyl polyethylene glycol phosphonate (HMGP) prepared in this example was subjected to the following tests:

[0052] (I) Characterization of the product HMGP

[0053] Figure 1 The infrared spectra of the reactant diethyl phosphite (DHPP) and the product hydroxymethyl polyethylene glycol phosphonate (HMGP) are shown in Figure 1. Figure 1 As can be seen, 3369cm -1 The absorption peak at 2987cm is generated by the stretching vibration of -OH. -1 and 2930cm -1 The absorption peak at 2431cm is attributed to the stretching vibration of -CH3 and -CH2. -1 is the stretching vibration of the PH bond, 1310cm -1 ,1220 -1 and 1043cm -1 The absorption peaks of DHPP are the stretching vibration absorption peaks of PC bond, P=O bond and POC bond. -1 There is a PH bond at 1310 cm-1, while the PH bond disappears in the FTIR curve of HMGP. -1 A new PC absorption peak appeared at 3369cm -1 A new -OH absorption peak appeared at , indicating that DHPP reacted with paraformaldehyde, indicating that there was a polyhydroxy polyethylene glycol phosphonate structure in the synthetic product.

[0054] To further characterize the product structure, DHPP and HMGP 1 H NMR and 31 P NMR Figure 2 and Figure 3 As shown. Figure 2 1 H NMR shows that the characteristic proton -CH2–CH2- has chemical shifts at Hc 3.45-3.60ppm and Ha 4.0-4.1ppm. 1H NMR comparison shows that the characteristic peak at 7.5 ppm (PH) disappears on HMGP, and the strong double peak e at 3.72 ppm is attributed to P-CH2-O protons. The two broad peaks b and d at 3.8-3.95 ppm on Hd and 5.1-5.7 ppm on Hb are attributed to the signal peaks of -OH, respectively.

[0055] In addition, by Figure 3 It can be seen that HMGP only appears at 24.1ppm 31 The P peak is attributed to the P atoms in HMGP, indicating that there is only one P chemical environment in the product. 1 H NMR and 31 The chemical structure of the synthesized product HMGP was confirmed by analyzing the P NMR spectrum.

[0056] (II) Performance of flame retardant rigid foamed polyurethane insulation materials

[0057] 1. Preparation of RPUF / HMGP material samples

[0058] The flame-retardant RPUF material was prepared by free foaming, and the material composition of each component is listed in Table 1. Polyether polyol HK-4110, phosphine-containing polyol HMGP, deionized water, dodecyl dimethylamine oxide foam stabilizer, triethylamine and n-hexane were added to a beaker in turn and stirred evenly. The mixture was then added to polymethylene polyphenyl isocyanate (PM-200), stirred at a rate of 1800r / min for 10s by a stirrer, and after it had obvious volume expansion, it was quickly transferred to the mold for free foaming, and then placed in a drying oven at 80°C for curing. Finally, the fully cured RPUF / HMGP material was cut into standard size samples with a high-temperature resistance wire for performance testing.

[0059] Table 1 Material composition of pure RPUF and flame retardant RPUF materials

[0060]

[0061] 2. Flame retardant properties of RPUF / HMGP materials

[0062] The flame retardancy of the material was tested by vertical burning (UL-94) and limiting oxygen index (LOI). Figure 4 As shown in Table 2, Figure 4The first row of pictures (a) are pure RPUF, and the second row of pictures (b) are RPUF / 15wt% HMGP materials. It can be seen that pure RPUF burns violently in the air, the LOI value is only 19.0%, and there is no grade in the UL-94 test. With the addition of HMGP, the flame retardant properties of RPUF materials are significantly improved. When 5% of HMGP is replaced, the material passes the UL-94V-1 grade. When the HMGP replacement amount reaches 15wt%, the material reaches the UL-94V-0 grade, and the LOI value increases to 24.2%.

[0063] Table 2 UL-94 and LOI value test results of RPUF / HMGP materials

[0064]

[0065] Compared with traditional phosphorus-containing flame retardants, the HMGP synthesized in the present invention exhibits excellent flame retardant properties in rigid foamed polyurethane materials. The flame retardant structure contains both PC and PO bond structures, and plays a good synergistic flame retardant role in the gas phase and the condensed phase.

[0066] 3. Combustion performance of RPUF / HMGP materials

[0067] Pure RPUF was quickly ignited after being exposed to thermal radiation, and the fire spread rapidly. The peak heat release rate reached 439.03kW / m 2 , as shown in Table 3, with high fire hazard. With the addition of HMGP, the combustion intensity of the material is significantly suppressed. When the replacement amount of HMGP reaches 15wt%, the peak heat release rate and total heat release of the material decrease by 47.3% and 44.1% respectively compared with pure RPUF.

[0068] Table 3 RPUF material combustion performance test results

[0069]

[0070] 4. Mechanical properties of RPUF / HMGP materials

[0071] In practical applications, flame-retardant RPUF materials also need to have good mechanical properties. With the addition of HMGP, due to its viscosity, the foaming is affected to a certain extent, making the pore structure of the material slightly smaller, and the apparent density of the material slightly increased (increased by 3.28%), but still maintaining good mechanical and thermal insulation properties, the compression strength decreased by 11.64%, and the thermal conductivity remained basically unchanged (as shown in Table 4), indicating that the polyurethane thermal insulation material of the present invention has high thermal insulation.

[0072] Table 4 Performance test results of RPUF / HMGP materials

[0073]

[0074] 5. Aging resistance of RPUF / HMGP materials

[0075] The aging resistance of flame-retardant RPUF / HMGP materials at high temperatures was tested in a thermoelectric constant temperature drying oven. At 140°C, LOI and UL-94 tests were performed on samples after aging times of 24h, 48h, 72h and 96h. The results showed that the materials maintained the UL-94V-0 grade after the aging test. After 96h of thermal aging, the LOI value of the material was 24.2%, showing excellent aging resistance. The HMGP flame retardant was introduced into the polyurethane molecular segment through chemical reaction, and has excellent migration resistance.

Claims

1. A polymeric phosphine-containing polyol, characterized in that: The polymeric phosphine-containing polyol is hydroxymethyl polyethylene glycol phosphonate, and its chemical structure is:

2. The method for preparing a polymeric phosphine-containing polyol according to claim 1, wherein: The method comprises the following steps:

1. Under anhydrous and oxygen-free reaction conditions, diethyl phosphite and catalyst 1 are added to a reaction device, and the mixture is heated to 120-130° C. by a constant temperature oil bath heating device under stirring, and then ethylene glycol is added dropwise to the reaction system. After the dropwise addition is completed, the system is heated to 140-160° C. and reacted for 6-8 hours. No more methanol is produced, and a filtering device is used for filtering. The product is fully washed with n-hexane to obtain an intermediate polyethylene glycol phosphate; 2. Add the prepared polyethylene glycol phosphate and catalyst 2 into a reaction device, add paraformaldehyde into the reaction system under stirring at room temperature, heat to 70-90° C., react for 4-6 hours, filter and wash after cooling to obtain hydroxymethyl polyethylene glycol phosphonate.

3. The method for preparing a polymeric phosphine-containing polyol according to claim 2, characterized in that: In step 1, the mass ratio of ethylene glycol to diethyl phosphite is 1:(1.8-2).

4. The method for preparing a polymeric phosphine-containing polyol according to claim 2 or 3, characterized in that: In step 1, the catalyst 1 is one or a mixture of titanium oxide, zinc oxide, iron oxide, magnesium oxide, and aluminum oxide, and the catalyst 1 accounts for 0.5% to 1% of the total mass of the reactants.

5. The method for preparing a polymeric phosphine-containing polyol according to claim 4, characterized in that: In step 2, the mass ratio of paraformaldehyde to polyethylene glycol phosphate is 1:(5.5-6).

6. The method for preparing a polymeric phosphine-containing polyol according to claim 5, characterized in that: In step 2, the catalyst 2 is one or a mixture of sodium hydroxide, potassium carbonate, potassium hydroxide, and the catalyst 2 accounts for 8% to 10% of the total mass of the reactants.

7. The method for preparing a polymeric phosphine-containing polyol according to claim 6, characterized in that: The heating rate in step 2 is 2-3°C / min.

8. Use of the polymeric phosphine-containing polyol as claimed in claim 1 in flame-retardant modified rigid foamed polyurethane thermal insulation materials.

9. The use according to claim 8, characterized in that: The specific preparation method of the rigid foamed polyurethane is: The polyol, foam stabilizer, n-hexane, triethylamine, dibutyltin dilaurate and deionized water are mixed and stirred evenly to obtain a mixture; the mixture is added to polymethylene polyphenyl isocyanate, foamed and cured to prepare a rigid foamed polyurethane. The polyol is a mixture of polymeric phosphine-containing polyol and polyether polyol, and the content of polymeric phosphine-containing polyol in the polyol is a, 0<a≤15%.

10. The use according to claim 9, characterized in that: The ratio of polymethylene polyphenyl isocyanate to polyether polyol is (1.1-1.4) to (1-1.2) according to the molar ratio of -NCO to -OH.

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