A bio-based flame-retardant polyurethane soft foam with photo-thermal conversion performance and a preparation method and application thereof

Abstract

The application discloses a bio-based flame-retardant polyurethane soft foam with photo-thermal conversion performance and a preparation method and application thereof, and comprises the following steps: reacting vanillyl alcohol (VA) with phenyl phosphorodichloridate (PPDC) to synthesize vanillyl alcohol-based phosphorus-containing dihydric alcohol, i.e., a flame-retardant polyol (PPDVA); uniformly mixing castor oil as a biomass material with the flame-retardant polyol, polytetrahydrofuran, MXene (Ti3C2T x ) powder, a foaming agent, a catalyst and a foam stabilizer to prepare a component A precursor solution; adding a component B isocyanate into the component A; and obtaining a polyurethane soft foam loaded with Ti3C2T x after foaming and curing; and immersing the polyurethane soft foam loaded with Ti3C2T x in a PDMS solution and performing ultrasonic treatment, and then solidifying in an oven to obtain the bio-based flame-retardant polyurethane soft foam with photo-thermal conversion performance. The polyurethane soft foam obtained by the application has superhydrophobicity, good photo-thermal conversion performance and good flame-retardant effect, and can be applied to the fields of oil-water separation and flame retardation; and the preparation method is simple, green, environment-friendly and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of bio-based polyurethane foam, and particularly relates to a bio-based flame-retardant polyurethane soft foam with photothermal conversion performance and a preparation method and application thereof. BACKGROUND

[0002] Polyurethane (PU) is the fifth largest synthetic polymer material, which plays a very important role in life and industry due to its good mechanical properties, thermal insulation and chemical resistance. Polyurethane foam has a wide range of applications in the construction, automotive and electronics industries, which require materials to have excellent performance in various aspects, such as oil-water separation, electromagnetic shielding, thermal insulation / fireproofing, etc.

[0003] Currently, the production raw materials of commercial polyurethane foam for oil-water separation mainly come from limited petrochemical resources, and the foam is usually directly discarded or incinerated after use, which will cause secondary pollution to the environment. Therefore, it is necessary to find a partial replacement of petrochemical resources with biomass resources to prepare environmentally friendly polyurethane soft foam oil absorption materials. Compared with commonly used petroleum-based polyols, vegetable oil has advantages such as abundant raw material sources, low energy consumption and good physical and chemical stability. Traditional polyurethane soft foam oil absorption materials are mainly used for treating light oil stains, but there are problems of slow adsorption efficiency and low oil-water separation efficiency for cleaning high-viscosity oil stains. With the increasing demand for crude oil exploitation, crude oil leakage accidents occur frequently, and how to quickly deal with the high-viscosity and low-flowability crude oil pollution has become a problem to be solved. Crude oil has temperature sensitivity, and its viscosity decreases with increasing temperature. Therefore, the development of polyurethane foam with photothermal conversion performance will be conducive to the rapid heating and adsorption of high-viscosity crude oil.

[0004] When using polyurethane foam to treat oil stains, the fire safety requirement is very high. However, due to the porous structure of polyurethane foam, oxygen can easily diffuse into the foam, accelerating the ignition process, so polyurethane foam has high flammability, which increases the risk of fire and poses a significant threat to personnel safety and property safety during use. Therefore, it is urgent to develop environmentally friendly flame-retardant polyurethane foam. The current research on flame-retardant polyurethane mainly includes additive and reaction type flame-retardant. The additive type flame-retardant is to add a substance with flame-retardant property to the polyurethane system in the form of a filler, mainly including inorganic, organic and composite flame-retardants, which has simple process and low cost, but the flame-retardant effect is not durable enough; the reaction type flame-retardant mainly realizes the flame-retardant purpose through the flame-retardant elements of phosphorus, nitrogen and silicon and the flame-retardant chemical structure itself. Unlike the additive type flame-retardant, the reaction type flame-retardant can be connected to the polyurethane base material through chemical bonds, thereby being well compatible with the polyurethane matrix, achieving the flame-retardant effect, and the special structure of some reaction type flame-retardants can also improve the mechanical and thermal properties of polyurethane. SUMMARY

[0005] The technical problem solved by the present application: In view of the shortcomings of the existing oil-water separation and flame-retardant material preparation technology, the present application provides a bio-based flame-retardant polyurethane soft foam with photo-thermal conversion performance, its preparation method and application. The polyurethane soft foam can be used for oil-water separation and has good photo-thermal conversion and flame-retardant performance.

[0006] Technical scheme: A preparation method of a bio-based flame-retardant polyurethane soft foam with photo-thermal conversion performance, comprising the following steps:

[0007] (1) Dissolve vanillyl alcohol in NaOH aqueous solution to obtain a brownish yellow phenolic sodium salt aqueous solution, then dissolve phenyl phosphorodichloridate in ethyl acetate, and add it dropwise into the phenolic sodium salt aqueous solution under ice bath conditions, wherein the molar ratio of vanillyl alcohol to phenyl phosphorodichloridate is 1.8-2.5:1, to obtain a light yellow liquid on the top, which is washed with NaOH aqueous solution and hot water respectively, and rotary evaporation to obtain a yellow viscous liquid, which is a flame-retardant polyol; (2) Mix 40-80 parts of castor oil, 0-20 parts of flame-retardant polyol, 20 parts of polytetrahydrofuran, 5-10 parts of MXene powder, 2.0-3.6 parts of foaming agent, 1.0-2.0 parts of catalyst and 1.2-2.4 parts of foam stabilizer by weight to prepare component A; add 55-65 parts of isocyanate component B to component A, and after foaming and curing, obtain a Ti3C2T x polyurethane soft foam loaded with MXene; x (3) Dip the Ti3C2T -1 polyurethane soft foam loaded with MXene in a 1wt.%-5wt.% PDMS n-hexane solution and ultrasonic treatment, and then oven dry and cure to obtain a bio-based flame-retardant polyurethane soft foam with photo-thermal conversion performance.

[0008] Preferably, in step (1), the molar ratio of vanillyl alcohol to phenyl phosphorodichloridate is 2.2:1, and the concentration of NaOH aqueous solution is 2.2 mol·L -1 .

[0009] Preferably, in step (1), the hydroxyl value of the flame-retardant polyol is 60-65 mg KOH·g -1 .

[0010] Preferably, in step (2), the weight ratio of each component is as follows: castor oil 40-80 parts, flame-retardant polyol 20 parts, polytetrahydrofuran 20 parts, MXene powder 8 parts, foaming agent 3.0 parts, catalyst 1.3 parts, foam stabilizer 1.8 parts, and isocyanate 55-65 parts.

[0011] Preferably, the catalyst in step (2) is at least one of triethylenediamine, N-methylmorpholine, N-ethylmorpholine and stannous octoate; the foam stabilizer is one of Momentive L580 and Momentive L-3881; and the isocyanate is any one of toluene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate and isophorone diisocyanate.

[0012] Preferably, the MXene powder in step (2) is single-layer Ti3C2T x powder.

[0013] Preferably, in step (2), the castor oil, polytetrahydrofuran and MXene powder in component A are stirred and then ultrasonically dispersed for 1-2 h to fully mix and homogenize, and then mixed with the flame-retardant polyol, foaming agent, catalyst and foam stabilizer at 600 r·min -1 for 3-6 min to mix and homogenize.

[0014] Preferably, in step (2), the temperature in the curing step is 50-100℃ and the time is 10-36 h; in step (3), the ultrasonic treatment time is 0-2 h, the curing temperature is 60-100℃ and the curing time is 10-24 h.

[0015] The bio-based flame-retardant polyurethane soft foam prepared by the above method has photo-thermal conversion performance.

[0016] The above bio-based flame-retardant polyurethane soft foam is used in oil-water separation and flame retardation.

[0017] Advantages: (1) In the present application, vanillin and castor oil derived from biomass resources are used to replace part of the petrochemical-based polyether polyol, and the prepared polyurethane soft foam is green and environmentally friendly, and has environmental friendliness;

[0018] (2) The bio-based polyurethane soft foam prepared in the present application has superhydrophobic and oleophilic properties, and the water contact angle can reach 154.6°, which can effectively realize continuous adsorption and separation of oil-water mixture;

[0019] (3) The castor oil-based polyurethane soft foam prepared in the present application has good photo-thermal conversion performance and flame retardation, and can be quickly heated to 95.3℃ under the condition of 1 sunlight, and the saturated adsorption capacity of crude oil can reach 4.92 g·g -1 , and the limiting oxygen index can reach about 27% of the flame retardation effect. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The nuclear magnetic resonance spectrum of the vanillin-based flame-retardant polyol prepared in Example 2.

[0021] Figure 2 The SEM image of the composite foam material prepared in Example 6.

[0022] Figure 3 Compression stress-strain curves of the foams prepared in Example 3 and Example 6 at 70% strain.

[0023] Figure 4 Thermogravimetric comparison of the composite foams prepared in Examples 3-6.

[0024] Figure 5 Absorption capacity of the composite foam prepared in Example 6 for various organic liquids and oils.

[0025] Figure 6 Process diagram of crude oil adsorption by the composite foam prepared in Example 6 with and without light.

[0026] Figure 7 Photo-thermal conversion of the composite foams prepared in Example 3 and Example 6. DETAILED DESCRIPTION

[0027] The following examples further illustrate the present application but are not to be construed as limiting. Modifications and adaptations of the methods, steps or conditions of the application described herein are possible by those skilled in the art without departing from the spirit and scope of the application. If not specifically mentioned, the technical means used in the examples are conventional means known to those skilled in the art.

[0028] Example 1

[0029] Step 1: Add 1.8 g LiF to 40 mL of 9M aqueous hydrochloric acid solution and stir for 10 min (500 r·min -1 ) in an ice bath to obtain a uniform etching solution; add 1.9 g of MAX (Ti3AlC2, 400 mesh, purchased from Foshan Xinyan Technology Co., Ltd.) and stir the reaction at 35°C for 24 hours, which can be appropriately extended to obtain a multi-layer MXene solution;

[0030] Step 2: Centrifuge the obtained solution at 4000 r·min -1 for 5 min, repeatedly wash with deionized water for 5-6 times, and ultrasonic for 1 h; repeat the centrifugation and add water to repeatedly peel off the lower sediment until a dark green Ti3C2T x suspension is obtained, and collect the prepared single-layer MXene solution;

[0031] Step 3: Freeze-dry the collected single-layer MXene solution for 48 h, and grind to obtain MXene powder.

[0032] Example 2

[0033] Step 1: 0.22 mol of vanillyl alcohol (33.9 g) was dissolved in 100 mL of NaOH (8.8 g, 0.22 mol) aqueous solution, stirred at room temperature for 10 min to generate a brownish yellow aqueous solution of phenolic sodium salt;

[0034] Step 2: 0.1 mol of phenyl phosphorodichloridate (19.5 g) was dissolved in 200 mL of ethyl acetate, and the phenolic sodium salt aqueous solution was added dropwise under ice bath conditions within 3 h, stirred, and after the dropwise addition was completed, the reaction was continued at room temperature for 1 h, and standing to obtain the upper layer of light yellow liquid;

[0035] Step 3: After washing with 4 wt% NaOH aqueous solution twice and hot water three times, rotary evaporation was performed to obtain a yellow viscous liquid, which was a flame-retardant polyol.

[0036] Example 3

[0037] Step 1: According to the weight parts, 80 parts of castor oil and 20 parts of polytetrahydrofuran were mixed in proportion, 3.0 parts of foaming agent deionized water, and 0.6 parts of triethylenediamine, 0.7 parts of stannous octoate and 1.8 parts of foam stabilizer Momentive L580 were added, and stirred at 600 r·min -1 for 5 min to mix uniformly, and the A component precursor solution was prepared, 62.5 parts of diphenylmethane diisocyanate was added, stirred at 1200 r·min -1 for 10 s, and naturally foamed, and cured at 60℃ for 24 h to obtain a polyurethane soft foam.

[0038] Example 4

[0039] Step 1: According to the weight parts, 60 parts of castor oil, 20 parts of polytetrahydrofuran and 20 parts of flame-retardant polyol with a hydroxyl value of 62.5 mg KOH·g -1 were mixed in proportion, 3.0 parts of foaming agent deionized water, and 0.6 parts of triethylenediamine, 0.7 parts of stannous octoate and 1.8 parts of foam stabilizer Momentive L580 were added, and stirred at 600 r·min -1 for 5 min to mix uniformly, and the A component precursor solution was prepared, 58.4 parts of diphenylmethane diisocyanate was added, stirred at 1200 r·min -1 for 10 s, and naturally foamed, and cured at 60℃ for 24 h to obtain a flame-retardant polyurethane soft foam.

[0040] Example 5

[0041] Step 1: According to the weight parts, 60 parts of castor oil, 20 parts of polytetrahydrofuran and 8 parts of MXene powder were stirred at 400 r·min -1 for 30 min and ultrasonically dispersed for 1 h to mix thoroughly, 20 parts of flame-retardant polyol with a hydroxyl value of 62.5 mg KOH·g -1flame-retardant polyol with a hydroxyl value of 62.5 mg KOH·g -1 After stirring for 5 min, the A component precursor solution was prepared, and 58.4 parts of diphenylmethane diisocyanate was added thereto. The solution was stirred at a rotational speed of 1200 r·min -1 for 10 s, naturally foamed, and cured at 60 °C for 24 h to obtain Ti3C2T x flame-retardant polyurethane soft foam.

[0042] Example 6

[0043] Step 1: 60 parts of castor oil, 20 parts of polytetrahydrofuran, and 8 parts of MXene powder were mixed at a mass ratio of 10:1 and dissolved in n-hexane to prepare a 1 wt.% PDMS n-hexane solution. -1 After stirring for 30 min and ultrasonic dispersion for 1 h, 20 parts of a flame-retardant polyol with a hydroxyl value of 62.5 mg KOH·g -1 flame-retardant polyol with a hydroxyl value of 62.5 mg KOH·g, 3.0 parts of a foaming agent deionized water, 0.6 parts of triethylenediamine, 0.7 parts of stannous octoate, and 1.8 parts of a foam stabilizer Momentive L580 were mixed at a mass ratio of 10:1 and dissolved in n-hexane to prepare a 1 wt.% PDMS n-hexane solution. -1 After stirring for 30 min and ultrasonic dispersion for 1 h, 20 parts of a flame-retardant polyol with a hydroxyl value of 62.5 mg KOH·g -1 for 10 s, naturally foamed, and cured at 60 °C for 24 h to obtain Ti3C2T x flame-retardant polyurethane soft foam.

[0044] Step 2: The PDMS and the curing agent were mixed at a mass ratio of 10:1 and dissolved in n-hexane to prepare a 1 wt.% PDMS n-hexane solution. The Ti3C2T x flame-retardant polyurethane soft foam was immersed in the 1 wt.% PDMS n-hexane solution and ultrasonically treated for 1 h, and then cured in an oven at 80 °C for 12 h to obtain a multifunctional castor oil-based polyurethane soft foam.

[0045] Table 1 Comparison of properties of multifunctional castor oil-based polyurethane soft foams prepared in various examples

[0046]

[0047] As shown in Table 1, the water contact angle of the multifunctional castor oil-based polyurethane soft foam prepared by the application is 95.9-154.6°, the compressive stress is 0.046-0.848 MPa, the flame retardant performance is represented by the limiting oxygen index (LOI), which can reach 16.3-27.3%, and the comprehensive performance of Example 6 is the best, the contact angle is 154.6°, the mechanical property test is carried out under the condition of 70% strain, the compressive stress can reach 0.848 MPa, and the limiting oxygen index of the flame retardant performance can reach 27.3%.

[0048] The flame-retardant polyol PPDVA prepared in Example 2 is subjected to 1 H NMR spectrum analysis, and the results are shown in Figure 1 , the corresponding relationship of each proton and proton peak has been marked, and the peak at 8.07-7.43 ppm represents the hydrogen in the benzene ring directly connected with the phosphorus atom. The peak values at 7.15-6.69 ppm, 4.51 ppm and 3.65 ppm represent the benzene ring, methylene and methoxy structure consistent with the vanillyl alcohol group.

[0049] The polyurethane composite foam prepared in Example 3 is subjected to SEM morphology characterization, and the results are shown in Figure 2 , the uniform rough structure of the foam surface indicates the successful loading of Ti3C2T x ; the insert represents the contact angle (WCA) of the composite foam, which reaches 154.6°, indicating that the foam has excellent superhydrophobicity.

[0050] The polyurethane foams prepared in Example 3 and Example 6 are subjected to mechanical property analysis, and the results are shown in Figure 3 , the compressive stress of Example 6 is significantly improved compared with that of Example 3 (0.112 MPa), which can reach 0.848 MPa, and has excellent mechanical properties, which improves the recyclability of the polyurethane soft foam.

[0051] The polyurethane foams prepared in Examples 3-6 are subjected to thermal performance analysis, and the thermogravimetric results are shown in Figure 4 , the carbon residue rate of Example 6 in nitrogen at 800℃ is as high as 16.52%, which is 12.38% higher than that of Example 3 (4.14%), because MXene (Ti3C2T x ) and flame-retardant polyol (vanillyl alcohol group containing phosphorus diol) improve the thermal stability and flame retardancy of the polyurethane foam material.

[0052] The polyurethane foam prepared in Example 6 is subjected to saturated adsorption capacity analysis, and the results are shown in Figure 5 , the adsorption experiments are carried out on different organic solvents and oils, among which the adsorption capacity of chloroform can reach 36.97 g·g -1 , and the adsorption capacity of soybean oil can reach 9.40 g·g-1 , it can reach 4.92g·g for crude oil -1 , indicating that the polyurethane foam has oil adsorption capacity. Combined with the contact angle, it further shows that the prepared composite foam has oil-water selective adsorption and separation properties and can be used for crude oil adsorption. The schematic diagram of the crude oil adsorption process with and without light conditions is shown in the figure. Figure 6 shown.

[0053] The photothermal conversion performance of the polyurethane foams prepared in Example 3 and Example 6 was analyzed. The results are as follows: Figure 7 As shown in the figure, under simulated light conditions, the composite foam can perform efficient photothermal conversion and can heat up to 95.3°C within 360s, which is 67.4°C higher than that of Example 3 (27.9°C).

[0054] The present invention uses castor oil, a widely available and renewable biomass, as the main raw material to prepare polyurethane foam, which is green and environmentally friendly; Ti3C2T x Compared to unmodified foam, polyurethane soft foam cured with PDMS exhibits superior mechanical properties and superhydrophobicity, enabling continuous oil-water separation. The resulting composite polyurethane foam exhibits excellent photothermal conversion performance and excellent flame retardancy, with a limiting oxygen index reaching 27.3% at peak performance. The multifunctionality of castor oil-based polyurethane foam broadens the application range of polyurethane foam.

Claims

1. A process for the preparation of bio-based flame-retardant flexible polyurethane foam with photothermal conversion properties, characterized in that, The method comprises the following steps: (1) dissolving vanillyl alcohol in NaOH aqueous solution to obtain a brownish yellow phenolic sodium salt aqueous solution, then dissolving phenyl phosphorodichloridate in ethyl acetate, and adding the phenyl phosphorodichloridate into the phenolic sodium salt aqueous solution drop by drop under ice bath condition, wherein the molar ratio of vanillyl alcohol to phenyl phosphorodichloridate is 1.8-2.5:1, to obtain a light yellow liquid, which is washed with NaOH aqueous solution and hot water respectively, and then rotary evaporated to obtain a yellow viscous liquid, which is a flame-retardant polyol; (2) mixing 40-80 parts of castor oil, 0-20 parts of the flame-retardant polyol, 20 parts of polytetrahydrofuran, 5-10 parts of MXene powder, 2.0-3.6 parts of a foaming agent, 1.0-2.0 parts of a catalyst and 1.2-2.4 parts of a foam stabilizer in a weight ratio to obtain an A component, wherein the MXene powder is single-layer Ti3C2T x powder; adding 55-65 parts of a B component isocyanate into the A component, and then foaming and curing to obtain a polyurethane soft foam loaded with Ti3C2T x ; (3) immersing the polyurethane soft foam loaded with Ti3C2T x in a 1wt.%-5wt.% PDMS n-hexane solution and ultrasonic treating, and then drying and curing to obtain a bio-based flame-retardant polyurethane soft foam with light-to-heat conversion performance.

2. The method for preparing the bio-based flame-retardant polyurethane soft foam with photothermal conversion performance according to claim 1, characterized in that: The molar ratio of vanillyl alcohol to phenylphosphonic dichloride in step (1) was 2.2:1, and the concentration of aqueous NaOH was 2.2 mol L -1 .

3. The method for preparing the bio-based flame-retardant polyurethane soft foam with photothermal conversion performance according to claim 1, characterized in that: The hydroxyl value of the flame-retardant polyol in step (1) is 60 to 65 mg KOH.g -1 .

4. The method for preparing the bio-based flame-retardant polyurethane soft foam with light-to-heat conversion performance according to claim 1, characterized in that: The weight ratio of each component in step (2) is as follows: castor oil 40-80 parts, flame-retardant polyol 20 parts, polytetrahydrofuran 20 parts, MXene powder 8 parts, foaming agent 3.0 parts, catalyst 1.3 parts, foam stabilizer 1.8 parts, and isocyanate 55-65 parts.

5. The method for preparing the bio-based flame-retardant polyurethane soft foam with light-to-heat conversion performance according to claim 1, characterized in that: In step (2), the catalyst is at least one of triethylenediamine, N-methylmorpholine, N-ethylmorpholine, and stannous octoate; the foam stabilizer is one of Maitian L580 and Maitian L-3881; and the isocyanate is any one of toluene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, and isophorone diisocyanate.

6. The method for preparing the bio-based flame-retardant polyurethane soft foam with light-to-heat conversion performance according to claim 1, characterized in that: In step (2), the castor oil, polytetrahydrofuran and MXene powder in the A component are first stirred and ultrasonically dispersed for 1-2 h to fully mix and uniform, and then mixed with the flame-retardant polyol, foaming agent, catalyst and foam stabilizer at 600 r·min -1 min under stirring.

7. The method for preparing the bio-based flame-retardant polyurethane soft foam with light-to-heat conversion performance according to claim 1, characterized in that: In step (2), the temperature in the curing step is 50-100°C, and the time is 10-36 h; in step (3), the ultrasonic treatment time is 0-2 h, the curing temperature is 60-100°C, and the curing time is 10-24 h.

8. A bio-based flame-retardant polyurethane soft foam with photo-thermal conversion performance prepared by the method according to any one of claims 1-7.

9. Use of the bio-based flame-retardant polyurethane soft foam according to claim 8 in oil-water separation and flame retardation.

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