Preparation Method of Elastic Polyurethane Material

Abstract

The present invention relates to the technical field of elastic polyurethane materials, and particularly to a preparation method of elastic polyurethane materials, comprising the following steps: (1) preparing a biomass-based polyol LBP; (2) synthesizing a photo-responsive chain extender ADE; (3) preparing a flame retardant modifier PNSFR; (4) preparing an elastic polyurethane material based on the LBP, ADE and PNSFR; By introducing the biomass-based polyol LBP, not only the dependence on petroleum resources is reduced, but also the renewable resource of lignin is utilized. The unique structure of LBP also improves the mechanical properties and thermal stability of the material; The introduction of the photo-responsive chain extender ADE endows the material with reversible photo-responsiveness, realizing the shape memory and self-healing functions. More importantly, the conjugated structure of ADE also enhances the mechanical properties and thermal stability of the material, achieving the synergistic improvement of functions and properties. The flame retardant modifier PNSFR significantly improves the flame retardancy of the material through the synergistic effect of phosphorus and nitrogen, reaching the UL-94 V-0 level.

Description

Technical Field

[0001] The present invention relates to the technical field of elastic polyurethane materials, and particularly to a preparation method of elastic polyurethane materials. Background Art

[0002] Polyurethane materials are widely used in industry and daily life due to their excellent mechanical properties, wear resistance, and flexible molecular design. However, with the progress of technology and the improvement of environmental protection awareness, traditional polyurethane materials face many challenges:

[0003] 1. Dependence on petroleum resources: Traditional polyurethanes are mainly based on petrochemical products, facing problems of resource depletion and environmental pollution. Although there are studies attempting to use bio-based polyols, such as soybean oil-based polyols or castor oil-based polyols, these materials often have problems such as insufficient mechanical properties and poor heat resistance.

[0004] 2. Single function: Conventional polyurethane materials usually only have basic mechanical properties and lack intelligent responsiveness. Although there are studies introducing functions such as shape memory and self-healing into polyurethanes, these functions are usually single and often come at the expense of other properties of the material.

[0005] 3. Insufficient flame retardancy: Polyurethane materials are flammable, which limits their application in some high-demand fields. Traditional additive flame retardants often reduce the mechanical properties of the material, while the effect of reactive flame retardants is not ideal enough.

[0006] 4. Poor water resistance: Polyurethane materials, especially polyether-based polyurethanes, are prone to hydrolysis when in long-term contact with water, resulting in performance degradation. Although there are studies improving water resistance by increasing the crosslinking density or introducing hydrophobic groups, it often affects the flexibility of the material.

[0007] 5. Insufficient environmental adaptability: The performance of most polyurethane materials will drop sharply at extreme temperatures, which limits their application in special environments.

[0008] 6. Difficult recycling: The chemical structure of traditional polyurethane materials makes them difficult to degrade and recycle, causing serious environmental problems.

[0009] Although the prior art has made progress in some aspects, it still cannot solve all the above problems simultaneously. For example, some studies have improved the environmental friendliness of the material by introducing bio-based components, but often sacrificed the mechanical properties; some studies have achieved intelligent responsiveness by adding photo-responsive groups, but affected the thermal stability of the material; and some studies have improved the flame retardancy by introducing phosphorus-nitrogen compounds, but reduced the flexibility of the material.

[0010] Therefore, there is an urgent need to develop a new type of polyurethane material that can simultaneously solve the above problems and achieve environmental friendliness, multi-functional intelligent response, high performance, and good environmental adaptability. Summary of the Invention

[0011] In view of the above problems, a preparation method of an elastic polyurethane material that can simultaneously solve these technical problems is developed.

[0012] The present invention discloses a preparation method of an elastic polyurethane material, comprising the following steps:

[0013] (1) Prepare biomass-based polyol LBP;

[0014] (2) Synthesize photo-responsive chain extender ADE;

[0015] (3) Prepare flame retardant modifier PNSFR;

[0016] (4) Prepare an elastic polyurethane material based on the LBP, ADE, and PNSFR.

[0017] Specifically, the step (1) includes:

[0018] (a) Dissolve 100 parts by weight of lignin in 500 parts by weight of 1 mol / L sodium hydroxide solution, add 3 - 7 parts by weight of TEMPO, and introduce oxygen at 23 - 27 °C for 4 - 6 hours;

[0019] (b) Cool the reaction solution to 0 - 5 °C, add 25 - 35 parts by weight of sodium borohydride, and react for 4 hours;

[0020] (c) Add 130 - 170 parts by weight of epichlorohydrin to the reaction solution and react at 48 - 52 °C for 6 - 8 hours;

[0021] (d) Adjust the pH to 6.5 - 7.5, filter, wash with water, and dry to obtain the LBP.

[0022] Specifically, the step (2) includes:

[0023] (a) Dissolve 100 parts by weight of p-nitroaniline in 300 parts by weight of 6 mol / L hydrochloric acid, and dropwise add 45 - 55 parts by weight of 20 wt% sodium nitrite aqueous solution at 0 - 5 °C;

[0024] (b) Drop the obtained diazonium salt solution into 62 - 72 parts by weight of an ice acetic acid solution of 30 wt% aniline and react at 0 - 5 °C for 2 hours;

[0025] (c) Filter and wash with water to obtain 4,4'-dinitroazobenzene;

[0026] (d) Dissolve the 4,4'-dinitroazobenzene in 300 parts by weight of concentrated hydrochloric acid, add 90 - 110 parts by weight of tin powder, and reflux at 78 - 82 °C for 6 hours;

[0027] (e) Adjust the pH to 10 - 11, filter, wash with water, and recrystallize to obtain 4,4'-diaminoazobenzene;

[0028] (f) Dissolve 50 parts by weight of the 4,4'-diaminoazobenzene in 200 parts by weight of DMF, dropwise add 75 - 85 parts by weight of a 50 wt% IPDI DMF solution, react at 0 - 5 °C for 2 hours, and then raise the temperature to 48 - 52 °C and react for 4 hours;

[0029] (g) Dropwise add 55 - 65 parts by weight of a 30 wt% ethylenediamine DMF solution to the resulting reaction solution, and react at 58 - 62 °C for 6 hours;

[0030] (h) Carry out vacuum distillation, washing, and drying to obtain the ADE.

[0031] Specifically, step (3) includes:

[0032] (a) Dissolve 100 parts by weight of pentaerythritol in 400 parts by weight of anhydrous dichloromethane, dropwise add 170 - 190 parts by weight of phosphoryl chloride at 0 - 5 °C, raise the temperature to reflux, and react for 6 - 8 hours;

[0033] (b) Cool to room temperature, add 140 - 160 parts by weight of melamine, and react at 48 - 52 °C for 10 - 12 hours;

[0034] (c) Add 110 - 130 parts by weight of allyl glycidyl ether to the resulting reaction solution, and react at 68 - 72 °C for 6 hours;

[0035] (d) Carry out vacuum distillation, washing, and drying to obtain the PNSFR.

[0036] Specifically, step (4) includes:

[0037] (a) Mix 30 - 50 parts by weight of the LBP and 50 - 70 parts by weight of polytetramethylene ether glycol PTMEG, and carry out vacuum dehydration at 48 - 52 °C for 2 hours;

[0038] (b) Cool to room temperature, add a measured amount of isophorone diisocyanate IPDI to make the [NCO] / [OH] molar ratio 1.03 - 1.07, and react at 58 - 62 °C for 2 - 3 hours to obtain a prepolymer;

[0039] (c) Add 8 - 12 parts by weight of the ADE and 4 - 6 parts by weight of the PNSFR to the prepolymer, and stir at 68 - 72 °C for 30 - 60 minutes;

[0040] (d) Add 0.05 - 0.15 parts by weight of dibutyltin dilaurate, stir for 5 - 10 minutes, and degas under vacuum for 10 - 15 minutes;

[0041] (e) Inject the degassed reaction solution into a mold preheated to 80 °C and cure at 78 - 82 °C for 24 hours;

[0042] (f) Post - treat the cured material at room temperature for 48 hours.

[0043] Specifically, the lignin is industrial - grade alkali lignin, having a hydroxyl value of 200 - 250 mg KOH / g and an average molecular weight of 2000 - 3000 g / mol.

[0044] Specifically, the LBP has a hydroxyl value of 350 - 450 mg KOH / g, an average molecular weight of 2500 - 3500 g / mol, and a hydroxyl functionality of 4 - 6.

[0045] Specifically, the ADE has a melting point of 150 - 160 °C, an amino content of 7.5 - 8.5 mmol / g, and an ultraviolet absorption peak at 320 - 340 nm.

[0046] Specifically, the PNSFR has a phosphorus content of 8 - 10 wt%, a nitrogen content of 12 - 15 wt%, an epoxy value of 0.2 - 0.3 eq / 100 g, and a softening point of 90 - 100 °C.

[0047] Specifically, the PTMEG has a number - average molecular weight of 2000 ± 100 g / mol and a hydroxyl value of 56 ± 2 mg KOH / g.

[0048] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0049] 1. Environmental friendliness: By introducing the biomass - based polyol LBP, not only the dependence on petroleum resources is reduced, but also the renewable resource lignin is utilized. The unique structure of LBP also improves the mechanical properties and thermal stability of the material, solving the problem of insufficient performance of traditional bio - based polyurethanes.

[0050] 2. Multifunctional intelligent response: The introduction of the photo - responsive chain extender ADE endows the material with reversible photo - responsiveness, realizing shape - memory and self - healing functions. More importantly, the conjugated structure of ADE also enhances the mechanical properties and thermal stability of the material, achieving a synergistic improvement of functions and properties.

[0051] 3. Excellent flame retardancy: The flame retardant modifier PNSFR significantly improves the flame retardancy of the material through the synergistic effect of phosphorus and nitrogen, reaching the UL-94 V-0 level. The multi-arm structure of PNSFR also increases the crosslinking density of the material, further improving the mechanical properties and thermal stability.

[0052] 4. Excellent water resistance: The aromatic structure of LBP, the conjugated structure of ADE, and the multi-arm structure of PNSFR form a dense network, effectively blocking the infiltration of water molecules and greatly improving the water resistance of the material.

[0053] 5. Wide temperature range of use: The material maintains good flexibility at low temperatures (low Tg) and excellent thermal stability at high temperatures, greatly expanding the application range.

[0054] 6. Potential degradability: The partial lignin structure retained in LBP provides a potential biodegradation pathway for the material, which is beneficial to the recycling of the material.

[0055] In summary, through the carefully designed and optimized molecular structure, the present invention realizes the organic unity of environmental friendliness, multi-functional intelligent response, high performance, and excellent environmental adaptability, providing innovative ideas and technical support for the development of a new generation of high-performance intelligent polyurethane materials. This material has broad application prospects in the fields of aerospace, automotive industry, electronic packaging, intelligent textiles, etc., and is expected to promote the technological upgrading and sustainable development of related industries. Detailed implementation manners

[0056] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0057] The raw materials used in the present invention are as follows:

[0058] Lignin: Industrial-grade alkali lignin, hydroxyl value 200 - 250 mg KOH / g, average molecular weight 2000 - 3000 g / mol;

[0059] TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical, CAS: 2564-83-2): Purity ≥ 98%;

[0060] Sodium borohydride (NaBH4, CAS: 16940-66-2): Purity ≥ 98%;

[0061] Epichlorohydrin (CAS: 106-89-8): Purity ≥ 99%;

[0062] p-Nitroaniline (CAS: 100-01-6): Purity ≥ 99%;

[0063] Sodium nitrite (CAS: 7632-00-0): Analytically pure;

[0064] Aniline (CAS: 62-53-3): Purity ≥ 99.5%;

[0065] Tin powder (CAS: 7440-31-5): Purity ≥ 99%;

[0066] Isophorone diisocyanate (IPDI, CAS: 4098-71-9): Purity ≥ 98%;

[0067] Ethylenediamine (CAS: 107-15-3): Purity ≥ 99%;

[0068] Pentaerythritol (CAS: 115-77-5): Purity ≥ 98%;

[0069] Phosphoryl chloride (CAS: 10025-87-3): Purity ≥ 98%;

[0070] Melamine (CAS: 108-78-1): Purity ≥ 99%;

[0071] Allyl glycidyl ether (CAS: 106-92-3): Purity ≥ 99%.

[0072] Example 1

[0073] A preparation method of an elastic polyurethane material, the preparation method of this example includes the following steps:

[0074] 1. Preparation of biomass-based polyol LBP:

[0075] (a) Dissolve 100 parts by weight of lignin (hydroxyl value 200 mg KOH / g, average molecular weight 2000 g / mol) in 500 parts by weight of 1 mol / L sodium hydroxide solution, add 3 parts by weight of TEMPO, and introduce oxygen (flow rate 2 L / min) at 23°C for 4 hours;

[0076] (b) Cool the reaction solution to 0°C, add 25 parts by weight of sodium borohydride, and react for 4 hours;

[0077] (c) Add 130 parts by weight of epichlorohydrin to the reaction solution and react at 48°C for 6 hours;

[0078] (d) Adjust the pH to 6.5 with hydrochloric acid, filter, wash with water, and vacuum dry at 60°C for 24 hours to obtain LBP.

[0079] The characteristics of the obtained LBP: hydroxyl value 350 mg KOH / g, average molecular weight 2500 g / mol, hydroxyl functionality 4.

[0080] 2. Synthesis of photo-responsive chain extender ADE:

[0081] (a) Dissolve 100 parts by weight of p-nitroaniline in 300 parts by weight of 6 mol / L hydrochloric acid, and dropwise add 45 parts by weight of 20 wt% sodium nitrite aqueous solution at 0 °C;

[0082] (b) Dropwise add the diazonium salt solution to 62 parts by weight of an ice acetic acid solution of 30 wt% aniline, and react at 0 °C for 2 hours;

[0083] (c) Filter and wash with water to obtain 4,4'-dinitroazobenzene;

[0084] (d) Dissolve 4,4'-dinitroazobenzene in 300 parts by weight of concentrated hydrochloric acid, add 90 parts by weight of tin powder, and reflux at 78 °C for 6 hours;

[0085] (e) Adjust the pH to 10 with sodium hydroxide, filter, wash with water, and recrystallize to obtain 4,4'-diaminoazobenzene;

[0086] (f) Dissolve 50 parts by weight of 4,4'-diaminoazobenzene in 200 parts by weight of DMF, dropwise add 75 parts by weight of a 50 wt% IPDI DMF solution, react at 0 °C for 2 hours, and then raise the temperature to 48 °C and react for 4 hours;

[0087] (g) Dropwise add 55 parts by weight of a 30 wt% ethylenediamine DMF solution to the reaction solution, and react at 58 °C for 6 hours;

[0088] (h) Carry out vacuum distillation, wash with ether, and vacuum dry to obtain ADE.

[0089] The characteristics of the obtained ADE: melting point 150 °C, amino group content 7.5 mmol / g, ultraviolet absorption peak 320 nm.

[0090] 3. Preparation of flame retardant modifier PNSFR:

[0091] (a) Dissolve 100 parts by weight of pentaerythritol in 400 parts by weight of anhydrous dichloromethane, dropwise add 170 parts by weight of phosphoryl chloride at 0 °C, raise the temperature to reflux, and react for 6 hours;

[0092] (b) Cool to room temperature, add 140 parts by weight of melamine, and react at 48 °C for 10 hours;

[0093] (c) Add 110 parts by weight of allyl glycidyl ether to the reaction solution, and react at 68 °C for 6 hours;

[0094] (d) Carry out vacuum distillation, wash with acetone, and dry under vacuum to obtain PNSFR.

[0095] The obtained PNSFR has the following characteristics: phosphorus content 8 wt%, nitrogen content 12 wt%, epoxy value 0.2 eq / 100 g, softening point 90 °C.

[0096] 4. Preparation of intelligent elastic polyurethane material:

[0097] (a) Mix 30 parts by weight of LBP and 70 parts by weight of PTMEG (Mn = 1900 g / mol, hydroxyl value 54 mg KOH / g), and carry out dehydration under reduced pressure (0.1 kPa) at 48 °C for 2 hours;

[0098] (b) Cool to room temperature, add a measured amount of IPDI ([NCO] / [OH] = 1.03), and react at 58 °C for 2 hours to obtain a prepolymer;

[0099] (c) Add 8 parts by weight of ADE and 4 parts by weight of PNSFR to the prepolymer, and stir at 68 °C for 30 minutes;

[0100] (d) Add 0.05 parts by weight of dibutyltin dilaurate, stir for 5 minutes, and carry out defoaming under vacuum (0.1 kPa) for 10 minutes;

[0101] (e) Inject the defoamed reaction solution into a mold preheated to 80 °C, and cure at 78 °C for 24 hours;

[0102] (f) Post-treat the cured material at room temperature for 48 hours.

[0103] Example 2

[0104] A preparation method of a polyurethane material. The preparation method of this example includes the following steps:

[0105] 1. Preparation of biomass-based polyol LBP:

[0106] (a) Dissolve 100 parts by weight of lignin (hydroxyl value 225 mg KOH / g, average molecular weight 2500 g / mol) in 500 parts by weight of 1 mol / L sodium hydroxide solution, add 5 parts by weight of TEMPO, and introduce oxygen (flow rate 2 L / min) at 25 °C, and react for 5 hours;

[0107] (b) Cool the reaction solution to 2.5 °C, add 30 parts by weight of sodium borohydride, and react for 4 hours;

[0108] (c) Add 150 parts by weight of epichlorohydrin to the reaction solution, and react at 50 °C for 7 hours;

[0109] (d) Adjust the pH to 7.0 with hydrochloric acid, filter, wash with water, and vacuum dry at 60 °C for 24 hours to obtain LBP.

[0110] The obtained LBP is characterized by: hydroxyl value 400 mg KOH / g, average molecular weight 3000 g / mol, and hydroxyl functionality 5.

[0111] 2. Synthesis of photo-responsive chain extender ADE:

[0112] (a) Dissolve 100 parts by weight of p-nitroaniline in 300 parts by weight of 6 mol / L hydrochloric acid, and dropwise add 50 parts by weight of 20 wt% sodium nitrite aqueous solution at 2.5 °C;

[0113] (b) Dropwise add the diazonium salt solution to 67 parts by weight of an ice acetic acid solution of 30 wt% aniline, and react at 2.5 °C for 2 hours;

[0114] (c) Filter and wash with water to obtain 4,4'-dinitroazobenzene;

[0115] (d) Dissolve 4,4'-dinitroazobenzene in 300 parts by weight of concentrated hydrochloric acid, add 100 parts by weight of tin powder, and reflux at 80 °C for 6 hours;

[0116] (e) Adjust the pH to 10.5 with sodium hydroxide, filter, wash with water, and recrystallize to obtain 4,4'-diaminoazobenzene;

[0117] (f) Dissolve 50 parts by weight of 4,4'-diaminoazobenzene in 200 parts by weight of DMF, dropwise add 80 parts by weight of a 50 wt% IPDI DMF solution, react at 2.5 °C for 2 hours, and then raise the temperature to 50 °C and react for 4 hours;

[0118] (g) Dropwise add 60 parts by weight of a 30 wt% ethylenediamine DMF solution to the reaction solution, and react at 60 °C for 6 hours;

[0119] (h) Carry out vacuum distillation, wash with ether, and vacuum dry to obtain ADE.

[0120] The obtained ADE is characterized by: melting point 155 °C, amino content 8.0 mmol / g, and ultraviolet absorption peak 330 nm.

[0121] 3. Preparation of flame retardant modifier PNSFR:

[0122] (a) Dissolve 100 parts by weight of pentaerythritol in 400 parts by weight of anhydrous dichloromethane, dropwise add 180 parts by weight of phosphoryl chloride at 2.5 °C, raise the temperature to reflux, and react for 7 hours;

[0123] (b) Cool to room temperature, add 150 parts by weight of melamine, and react at 50 °C for 11 hours;

[0124] (c) Add 120 parts by weight of allyl glycidyl ether to the reaction solution and react at 70 °C for 6 hours;

[0125] (d) Perform vacuum distillation, wash with acetone, and dry under vacuum to obtain PNSFR.

[0126] The obtained PNSFR is characterized by a phosphorus content of 9 wt%, a nitrogen content of 13.5 wt%, an epoxy value of 0.25 eq / 100 g, and a softening point of 95 °C.

[0127] 4. Preparation of intelligent elastic polyurethane material:

[0128] (a) Mix 40 parts by weight of LBP and 60 parts by weight of PTMEG (Mn = 2000 g / mol, hydroxyl value 56 mg KOH / g), and dehydrate under reduced pressure (0.05 kPa) at 50 °C for 2 hours;

[0129] (b) Cool to room temperature, add a measured amount of IPDI ([NCO] / [OH] = 1.05), and react at 60 °C for 2.5 hours to obtain a prepolymer;

[0130] (c) Add 10 parts by weight of ADE and 5 parts by weight of PNSFR to the prepolymer and stir at 70 °C for 45 minutes;

[0131] (d) Add 0.1 part by weight of dibutyltin dilaurate, stir for 7.5 minutes, and defoam under vacuum (0.05 kPa) for 12.5 minutes;

[0132] (e) Inject the defoamed reaction solution into a mold preheated to 80 °C and cure at 80 °C for 24 hours;

[0133] (f) Post-treat the cured material at room temperature for 48 hours.

[0134] Example 3

[0135] A preparation method of an elastic polyurethane material. The preparation method of this example includes the following steps:

[0136] 1. Preparation of biomass-based polyol LBP:

[0137] (a) Dissolve 100 parts by weight of lignin (hydroxyl value 250 mg KOH / g, average molecular weight 3000 g / mol) in 500 parts by weight of 1 mol / L sodium hydroxide solution, add 7 parts by weight of TEMPO, and introduce oxygen (flow rate 2 L / min) at 27 °C and react for 6 hours;

[0138] (b) Cool the reaction solution to 5 °C, add 35 parts by weight of sodium borohydride, and react for 4 hours;

[0139] (c) Add 170 parts by weight of epichlorohydrin to the reaction solution and react at 52 °C for 8 hours;

[0140] (d) Adjust the pH to 7.5 with hydrochloric acid, filter, wash with water, and vacuum dry at 60 °C for 24 hours to obtain LBP.

[0141] The characteristics of the obtained LBP are as follows: hydroxyl value 450 mg KOH / g, average molecular weight 3500 g / mol, and hydroxyl functionality 6.

[0142] 2. Synthesis of photo-responsive chain extender ADE:

[0143] (a) Dissolve 100 parts by weight of p-nitroaniline in 300 parts by weight of 6 mol / L hydrochloric acid, and dropwise add 55 parts by weight of 20 wt% sodium nitrite aqueous solution at 5 °C;

[0144] (b) Dropwise add the diazonium salt solution to 72 parts by weight of an ice acetic acid solution of 30 wt% aniline and react at 5 °C for 2 hours;

[0145] (c) Filter and wash with water to obtain 4,4'-dinitroazobenzene;

[0146] (d) Dissolve 4,4'-dinitroazobenzene in 300 parts by weight of concentrated hydrochloric acid, add 110 parts by weight of tin powder, and reflux at 82 °C for 6 hours;

[0147] (e) Adjust the pH to 11 with sodium hydroxide, filter, wash with water, and recrystallize to obtain 4,4'-diaminoazobenzene;

[0148] (f) Dissolve 50 parts by weight of 4,4'-diaminoazobenzene in 200 parts by weight of DMF, dropwise add 85 parts by weight of a 50 wt% IPDI DMF solution, react at 5 °C for 2 hours, and then raise the temperature to 52 °C and react for 4 hours;

[0149] (g) Dropwise add 65 parts by weight of a 30 wt% ethylenediamine DMF solution to the reaction solution and react at 62 °C for 6 hours;

[0150] (h) Carry out vacuum distillation, wash with ether, and vacuum dry to obtain ADE.

[0151] The characteristics of the obtained ADE are as follows: melting point 160 °C, amino content 8.5 mmol / g, and ultraviolet absorption peak 340 nm.

[0152] 3. Preparation of flame retardant modifier PNSFR:

[0153] (a) Dissolve 100 parts by weight of pentaerythritol in 400 parts by weight of anhydrous dichloromethane, dropwise add 190 parts by weight of phosphoryl chloride at 5 °C, raise the temperature to reflux, and react for 8 hours;

[0154] (b) Cool to room temperature, add 160 parts by weight of melamine, and react at 52 °C for 12 hours;

[0155] (c) Add 130 parts by weight of allyl glycidyl ether to the reaction solution, and react at 72 °C for 6 hours;

[0156] (d) Carry out vacuum distillation, wash with acetone, and dry under vacuum to obtain PNSFR.

[0157] The obtained PNSFR has the following characteristics: phosphorus content 10 wt%, nitrogen content 15 wt%, epoxy value 0.3 eq / 100 g, softening point 100 °C.

[0158] 4. Preparation of intelligent elastic polyurethane material:

[0159] (a) Mix 50 parts by weight of LBP and 50 parts by weight of PTMEG (Mn = 2100 g / mol, hydroxyl value 58 mg KOH / g), and dehydrate under reduced pressure (0.01 kPa) at 52 °C for 2 hours;

[0160] (b) Cool to room temperature, add a measured amount of IPDI ([NCO] / [OH] = 1.07), and react at 62 °C for 3 hours to obtain a prepolymer;

[0161] (c) Add 12 parts by weight of ADE and 6 parts by weight of PNSFR to the prepolymer, and stir at 72 °C for 60 minutes;

[0162] (d) Add 0.15 parts by weight of dibutyltin dilaurate, stir for 10 minutes, and defoam under vacuum (0.01 kPa) for 15 minutes;

[0163] (e) Inject the defoamed reaction solution into a mold preheated to 80 °C, and cure at 82 °C for 24 hours;

[0164] (f) Post-treat the cured material at room temperature for 48 hours.

[0165] Example 4

[0166] A preparation method of an elastic polyurethane material. The preparation method of this example includes the following steps:

[0167] 1. Preparation of biomass-based polyol LBP:

[0168] (a) Dissolve 100 parts by weight of lignin (hydroxyl value 225 mg KOH / g, average molecular weight 2500 g / mol) in 500 parts by weight of 1 mol / L sodium hydroxide solution, add 5 parts by weight of TEMPO, and introduce oxygen (flow rate 2 L / min) at 25 °C, and react for 5 hours;

[0169] (b) Cool the reaction solution to 2.5 °C, add 30 parts by weight of sodium borohydride, and react for 4 hours;

[0170] (c) Add 150 parts by weight of epichlorohydrin to the reaction solution and react at 50 °C for 7 hours;

[0171] (d) Adjust the pH to 7.0 with hydrochloric acid, filter, wash with water, and vacuum dry at 60 °C for 24 hours to obtain LBP.

[0172] The obtained LBP has the following characteristics: hydroxyl value 400 mg KOH / g, average molecular weight 3000 g / mol, and hydroxyl functionality 5.

[0173] 2. Synthesis of photo-responsive chain extender ADE:

[0174] (a) Dissolve 100 parts by weight of p-nitroaniline in 300 parts by weight of 6 mol / L hydrochloric acid, and dropwise add 50 parts by weight of 20 wt% sodium nitrite aqueous solution at 2.5 °C;

[0175] (b) Dropwise add the diazonium salt solution to 67 parts by weight of an ice acetic acid solution of 30 wt% aniline and react at 2.5 °C for 2 hours;

[0176] (c) Filter and wash with water to obtain 4,4'-dinitroazobenzene;

[0177] (d) Dissolve 4,4'-dinitroazobenzene in 300 parts by weight of concentrated hydrochloric acid, add 100 parts by weight of tin powder, and reflux at 80 °C for 6 hours;

[0178] (e) Adjust the pH to 10.5 with sodium hydroxide, filter, wash with water, and recrystallize to obtain 4,4'-diaminoazobenzene;

[0179] (f) Dissolve 50 parts by weight of 4,4'-diaminoazobenzene in 200 parts by weight of DMF, dropwise add 80 parts by weight of a 50 wt% IPDI DMF solution, react at 2.5 °C for 2 hours, and then raise the temperature to 50 °C and react for 4 hours;

[0180] (g) Dropwise add 60 parts by weight of a 30 wt% ethylenediamine DMF solution to the reaction solution and react at 60 °C for 6 hours;

[0181] (h) Carry out vacuum distillation, wash with ether, and vacuum dry to obtain ADE.

[0182] The obtained ADE has the following characteristics: melting point 155 °C, amino content 8.0 mmol / g, and ultraviolet absorption peak 330 nm.

[0183] 3. Preparation of flame retardant modifier PNSFR:

[0184] (a) Dissolve 100 parts by weight of pentaerythritol in 400 parts by weight of anhydrous dichloromethane, dropwise add 180 parts by weight of phosphoryl chloride at 2.5 °C, raise the temperature to reflux, and react for 7 hours;

[0185] (b) Cool to room temperature, add 150 parts by weight of melamine, and react at 50 °C for 11 hours;

[0186] (c) Add 120 parts by weight of allyl glycidyl ether to the reaction solution, and react at 70 °C for 6 hours;

[0187] (d) Carry out vacuum distillation, wash with acetone, and vacuum dry to obtain PNSFR.

[0188] The obtained PNSFR is characterized by: phosphorus content 9 wt%, nitrogen content 13.5 wt%, epoxy value 0.25 eq / 100 g, softening point 95 °C.

[0189] 4. Preparation of intelligent elastic polyurethane material:

[0190] (a) Mix 45 parts by weight of LBP and 55 parts by weight of PTMEG (Mn = 2000 g / mol, hydroxyl value 56 mg KOH / g), and dehydrate under reduced pressure (0.05 kPa) at 50 °C for 2 hours;

[0191] (b) Cool to room temperature, add a measured amount of IPDI ([NCO] / [OH] = 1.05), and react at 60 °C for 2.5 hours to obtain a prepolymer;

[0192] (c) Add 11 parts by weight of ADE and 5.5 parts by weight of PNSFR to the prepolymer, and stir at 70 °C for 45 minutes;

[0193] (d) Add 0.1 part by weight of dibutyltin dilaurate, stir for 7.5 minutes, and defoam under vacuum (0.05 kPa) for 12.5 minutes;

[0194] (e) Inject the defoamed reaction solution into a mold preheated to 80 °C, and cure at 80 °C for 24 hours;

[0195] (f) Post-treat the cured material at room temperature for 48 hours.

[0196] Comparative Example 1: Lack of biomass-based polyol LBP (corresponding to Example 1)

[0197] The preparation method of this comparative example includes the following steps:

[0198] 1. Synthesis of photo-responsive chain extender ADE:

[0199] Carry out according to the method in Example 1.

[0200] 2. Preparation of flame retardant modifier PNSFR:

[0201] Carry out according to the method in Example 1.

[0202] 3. Preparation of polyurethane material:

[0203] (a) Dehydrate 100 parts by weight of PTMEG (Mn = 1900 g / mol, hydroxyl value 54 mg KOH / g) under reduced pressure (0.1 kPa) at 48 °C for 2 hours;

[0204] (b) Cool to room temperature, add a measured amount of IPDI ([NCO] / [OH] = 1.03), and react at 58 °C for 2 hours to obtain a prepolymer;

[0205] (c) Add 8 parts by weight of ADE and 4 parts by weight of PNSFR to the prepolymer, and stir at 68 °C for 30 minutes;

[0206] (d) Add 0.05 part by weight of dibutyltin dilaurate, stir for 5 minutes, and defoam under vacuum (0.1 kPa) for 10 minutes;

[0207] (e) Inject the defoamed reaction solution into a mold preheated to 80 °C, and cure at 78 °C for 24 hours;

[0208] (f) Post-treat the cured material at room temperature for 48 hours.

[0209] Comparative Example 2: Replace the photo-responsive chain extender ADE with the traditional chain extender 1,4-butanediol (corresponding to Example 2)

[0210] The preparation method of this comparative example includes the following steps:

[0211] 1. Preparation of biomass-based polyol LBP:

[0212] Carry out according to the method in Example 2.

[0213] 2. Preparation of flame retardant modifier PNSFR:

[0214] Carry out according to the method in Example 2.

[0215] 3. Preparation of polyurethane material:

[0216] (a) Mix 40 parts by weight of LBP and 60 parts by weight of PTMEG (Mn = 2000 g / mol, hydroxyl value 56 mg KOH / g), and dehydrate under reduced pressure (0.05 kPa) at 50 °C for 2 hours;

[0217] (b) Cool to room temperature, add a measured amount of IPDI ([NCO] / [OH] = 1.05), and react at 60 °C for 2.5 hours to obtain a prepolymer;

[0218] (c) Add 10 parts by weight of 1,4 - butanediol and 5 parts by weight of PNSFR to the prepolymer, and stir at 70 °C for 45 minutes;

[0219] (d) Add 0.1 part by weight of dibutyltin dilaurate, stir for 7.5 minutes, and defoam under vacuum (0.05 kPa) for 12.5 minutes;

[0220] (e) Inject the defoamed reaction solution into a mold preheated to 80 °C, and cure at 80 °C for 24 hours;

[0221] (f) Post - treat the cured material at room temperature for 48 hours.

[0222] Comparative Example 3: Lack of flame - retardant modifier PNSFR (corresponding to Example 3)

[0223] The preparation method of this comparative example includes the following steps:

[0224] 1. Preparation of biomass - based polyol LBP:

[0225] Carry out according to the method in Example 3.

[0226] 2. Synthesis of photo - responsive chain extender ADE:

[0227] Carry out according to the method in Example 3.

[0228] 3. Preparation of polyurethane material:

[0229] (a) Mix 50 parts by weight of LBP and 50 parts by weight of PTMEG (Mn = 2100 g / mol, hydroxyl value 58 mg KOH / g), and dehydrate under reduced pressure (0.01 kPa) at 52 °C for 2 hours;

[0230] (b) Cool to room temperature, add a measured amount of IPDI ([NCO] / [OH] = 1.07), and react at 62 °C for 3 hours to obtain a prepolymer;

[0231] (c) Add 12 parts by weight of ADE to the prepolymer, and stir at 72 °C for 60 minutes;

[0232] (d) Add 0.15 part by weight of dibutyltin dilaurate, stir for 10 minutes, and defoam under vacuum (0.01 kPa) for 15 minutes;

[0233] (e) Inject the defoamed reaction solution into a mold preheated to 80 °C, and cure at 82 °C for 24 hours;

[0234] (f) Post - treat the cured material at room temperature for 48 hours.

[0235] Comparative Example 4: Excessive content of biomass-based polyol LBP (corresponding to Example 4)

[0236] The preparation method of this comparative example includes the following steps:

[0237] 1. Preparation of biomass-based polyol LBP:

[0238] Carry out according to the method in Example 4.

[0239] 2. Synthesis of photo-responsive chain extender ADE:

[0240] Carry out according to the method in Example 4.

[0241] 3. Preparation of flame retardant modifier PNSFR:

[0242] Carry out according to the method in Example 4.

[0243] 4. Preparation of polyurethane material:

[0244] (a) Mix 80 parts by weight of LBP and 20 parts by weight of PTMEG (Mn = 2000 g / mol, hydroxyl value 56 mg KOH / g), and dehydrate under reduced pressure (0.05 kPa) at 50 °C for 2 hours;

[0245] (b) Cool to room temperature, add metered IPDI ([NCO] / [OH] = 1.05), and react at 60 °C for 2.5 hours to obtain a prepolymer;

[0246] (c) Add 11 parts by weight of ADE and 5.5 parts by weight of PNSFR to the prepolymer, and stir at 70 °C for 45 minutes;

[0247] (d) Add 0.1 part by weight of dibutyltin dilaurate, stir for 7.5 minutes, and defoam under vacuum (0.05 kPa) for 12.5 minutes;

[0248] (e) Inject the defoamed reaction solution into a mold preheated to 80 °C, and cure at 80 °C for 24 hours;

[0249] (f) Post-treat the cured material at room temperature for 48 hours.

[0250] Comparative Example 5: Too low content of photo-responsive chain extender ADE (corresponding to Example 1)

[0251] The preparation method of this comparative example includes the following steps:

[0252] 1. Preparation of biomass-based polyol LBP:

[0253] Carry out according to the method in Example 1.

[0254] 2. Synthesis of photo-responsive chain extender ADE:

[0255] Carry out according to the method in Example 1.

[0256] 3. Preparation of flame retardant modifier PNSFR:

[0257] Carry out according to the method in Example 1.

[0258] 4. Preparation of polyurethane material:

[0259] (a) Mix 30 parts by weight of LBP and 70 parts by weight of PTMEG (Mn = 1900 g / mol, hydroxyl value 54 mg KOH / g), and dehydrate under reduced pressure (0.1 kPa) at 48 °C for 2 hours;

[0260] (b) Cool to room temperature, add metered IPDI ([NCO] / [OH] = 1.03), and react at 58 °C for 2 hours to obtain a prepolymer;

[0261] (c) Add 2 parts by weight of ADE and 4 parts by weight of PNSFR to the prepolymer, and stir at 68 °C for 30 minutes;

[0262] (d) Add 0.05 parts by weight of dibutyltin dilaurate, stir for 5 minutes, and defoam under vacuum (0.1 kPa) for 10 minutes;

[0263] (e) Inject the defoamed reaction solution into a mold preheated to 80 °C, and cure at 78 °C for 24 hours;

[0264] (f) Post-treat the cured material at room temperature for 48 hours.

[0265] Comparative Example 6: Excessive content of flame retardant modifier PNSFR (corresponding to Example 2)

[0266] The preparation method of this comparative example includes the following steps:

[0267] 1. Preparation of biomass-based polyol LBP:

[0268] Carry out according to the method in Example 2.

[0269] 2. Synthesis of photo-responsive chain extender ADE:

[0270] Carry out according to the method in Example 2.

[0271] 3. Preparation of flame retardant modifier PNSFR:

[0272] Carry out according to the method in Example 2.

[0273] 4. Preparation of polyurethane material:

[0274] (a) Mix 40 parts by weight of LBP and 60 parts by weight of PTMEG (Mn = 2000 g / mol, hydroxyl value 56 mg KOH / g), and dehydrate under reduced pressure (0.05 kPa) at 50 °C for 2 hours;

[0275] (b) Cool to room temperature, add a measured amount of IPDI ([NCO] / [OH] = 1.05), and react at 60 °C for 2.5 hours to obtain a prepolymer;

[0276] (c) Add 10 parts by weight of ADE and 20 parts by weight of PNSFR to the prepolymer, and stir at 70 °C for 45 minutes;

[0277] (d) Add 0.1 part by weight of dibutyltin dilaurate, stir for 7.5 minutes, and defoam under vacuum (0.05 kPa) for 12.5 minutes;

[0278] (e) Inject the defoamed reaction solution into a mold preheated to 80 °C, and cure at 80 °C for 24 hours;

[0279] (f) Post-treat the cured material at room temperature for 48 hours.

[0280] To verify the effectiveness of the present invention, the applicant designed the following models for testing:

[0281] The experimental method is as follows:

[0282] 1. Mechanical property testing

[0283] Equipment: Instron 5967 universal material testing machine

[0284] Method: According to ASTM D638 standard, test the tensile strength, elongation at break, and Young's modulus of the sample. The test speed is 50 mm / min, the temperature is 23 ± 2 °C, and the relative humidity is 50 ± 5%.

[0285] 2. Dynamic mechanical analysis (DMA)

[0286] Equipment: TA Instruments Q800 DMA analyzer

[0287] Method: Adopt the single-cantilever mode, the frequency is 1 Hz, the heating rate is 3 °C / min, and the temperature range is from -100 °C to 200 °C. Test the glass transition temperature (Tg) and storage modulus (E').

[0288] 3. Thermogravimetric analysis (TGA)

[0289] Equipment: PerkinElmer TGA 8000

[0290] Method: Under a nitrogen atmosphere, heat from room temperature to 800 °C at a heating rate of 10 °C / min to test the thermal stability and decomposition temperature of the sample.

[0291] 4. Flame Retardancy Test

[0292] Equipment: UL-94 Vertical Burning Tester

[0293] Method: Conduct a vertical burning test according to the UL-94 standard to evaluate the flame retardancy grade of the material.

[0294] 5. Photoresponsivity Test

[0295] Equipment: Self-made light irradiation device and Instron 5967 universal material testing machine

[0296] Method: Irradiate the sample with 365 nm ultraviolet light for 10 minutes, and then test the changes in its tensile strength and elongation at break. Then irradiate the sample with visible light for 10 minutes and test its recovery.

[0297] 6. Water Resistance Test

[0298] Method: Immerse the sample in deionized water at 23 °C for 7 days and test the changes in its mass and mechanical properties.

[0299] The test results are shown in the following table:

[0300] Table 1. Test Results of Mechanical Properties and Thermal Properties

[0301]

[0302] Table 2. Test Results of Flame Retardancy, Photoresponsivity and Water Resistance

[0303]

[0304] According to the test results, Example 3 shows the best performance and can be regarded as the best example.

[0305] Result analysis and the present invention have the following unexpected technical effects:

[0306] 1. Excellent mechanical properties: The tensile strength, elongation at break and Young's modulus of Examples 1-4 are all better than those of the comparative examples. This is due to the synergistic effect of biomass-based polyol LBP, photo-responsive chain extender ADE and flame retardant modifier PNSFR. The rigid structure of LBP enhances the strength of the material, the reversible photo-responsivity of ADE improves the toughness of the material, and the multi-arm structure of PNSFR increases the crosslinking density.

[0307] 2. Significantly improved thermal stability: The 5% mass loss temperature of the embodiment is 20-50°C higher than that of the comparative example. This significant improvement in thermal stability is due to the synergistic effect of the aromatic structure of LBP, the conjugated structure of ADE, and the phosphorus and nitrogen of PNSFR. In particular, the phosphate esters and phosphorus and nitrogen compounds formed during the thermal decomposition of PNSFR can effectively block heat and oxygen to form a protective layer.

[0308] 3. Excellent flame retardant properties: All examples achieved UL-94 V-0 rating, while most of the comparative examples failed to achieve it. This indicates that PNSFR not only provides a flame retardant effect, but also has a synergistic effect with LBP and ADE, probably due to the aromatic structure of LBP and the conjugated structure of ADE forming a stable char layer during combustion.

[0309] 4. Significant photoresponsiveness: After UV irradiation, the strength of the examples decreased by 15-20% and the elongation increased by 22-28%, which is much better than the comparative examples. This significant photoresponsiveness originates from the azobenzene structure of ADE, which undergoes cis-trans isomerization under UV light. More interestingly, this responsiveness seems to be enhanced by LBP and PNSFR, probably because they improve the dispersibility and freedom of movement of ADE in polyurethane.

[0310] 5. Excellent water resistance: The mass change of the example after 7 days of immersion in water is less than 1%, and the strength retention rate exceeds 93%, which is much better than the comparative example. This excellent water resistance may be due to the combined effect of the hydrophobic aromatic structure of LBP, the conjugated structure of ADE and the multi-arm structure of PNSFR, which form a dense network structure and effectively block the penetration of water molecules.

[0311] 6. Wide temperature range: The Tg of the embodiment is low (about -30°C) and the thermal stability is high, indicating that the material still maintains good flexibility at low temperatures and can maintain structural stability at high temperatures. This wide temperature range is the result of the balance between the rigid structure of LBP and the flexible chain segment of PTMEG. At the same time, the introduction of ADE and PNSFR further optimizes the microstructure of the material.

[0312] In summary, the present invention achieves multiple synergistic enhancement effects of mechanical properties, thermal stability, flame retardancy, light responsiveness and water resistance through the ingenious combination of biomass-based polyol LBP, light-responsive chain extender ADE and flame retardant modifier PNSFR. This multifunctional, high-performance smart elastic polyurethane material has broad application prospects in the fields of aerospace, automotive industry, electronic packaging and smart textiles.

[0313] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. A method for preparing an elastic polyurethane material, characterized in that: The following steps are involved: (1) Preparation of biomass-based polyol LBP; (2) Synthesis of photoresponsive chain extender ADE; (3) preparing flame retardant modifier PNSFR; (4) preparing an elastic polyurethane material based on the LBP, ADE and PNSFR; The step (1) comprises: (a) dissolving 100 parts by weight of lignin in 500 parts by weight of 1 mol / L sodium hydroxide solution, adding 3-7 parts by weight of TEMPO, introducing oxygen at 23-27° C., and reacting for 4-6 hours; (b) cooling the reaction solution to 0-5° C., adding 25-35 parts by weight of sodium borohydride, and reacting for 4 hours; (c) adding 130-170 parts by weight of epichlorohydrin to the reaction solution, and reacting at 48-52° C. for 6-8 hours; (d) adjusting the pH to 6.5-7.5, filtering, washing, and drying to obtain the LBP; The step (2) comprises: (a) dissolving 100 parts by weight of p-nitroaniline in 300 parts by weight of 6 mol / L hydrochloric acid, and adding dropwise 45-55 parts by weight of a 20 wt% sodium nitrite aqueous solution at 0-5° C.; (b) adding the obtained diazonium salt solution dropwise to 62-72 parts by weight of a 30 wt% aniline solution in glacial acetic acid, and reacting at 0-5° C. for 2 hours; (c) filtering and washing with water to obtain 4,4'-dinitroazobenzene; (d) dissolving the 4,4'-dinitroazobenzene in 300 parts by weight of concentrated hydrochloric acid, adding 90-110 parts by weight of tin powder, and refluxing at 78-82° C. for 6 hours; (e) adjusting the pH to 10-11, filtering, washing with water, and recrystallizing to obtain 4,4'-diaminoazobenzene; (f) dissolving 50 parts by weight of the 4,4'-diaminoazobenzene in 200 parts by weight of DMF, adding dropwise 75-85 parts by weight of a 50 wt% IPDI DMF solution, reacting at 0-5° C. for 2 hours, and heating to 48-52° C. for 4 hours; (g) adding 55-65 parts by weight of a 30 wt% DMF solution of ethylenediamine to the obtained reaction solution, and reacting at 58-62° C. for 6 hours; (h) distilling under reduced pressure, washing, and drying to obtain the ADE; The step (3) comprises: (a) dissolving 100 parts by weight of pentaerythritol in 400 parts by weight of anhydrous dichloromethane, adding dropwise 170-190 parts by weight of phosphoryl chloride at 0-5° C., raising the temperature to reflux, and reacting for 6-8 hours; (b) cooling to room temperature, adding 140-160 parts by weight of melamine, and reacting at 48-52° C. for 10-12 hours; (c) adding 110-130 parts by weight of allyl glycidyl ether to the obtained reaction solution, and reacting at 68-72° C. for 6 hours; (d) distilling under reduced pressure, washing and drying to obtain the PNSFR; The step (4) comprises: (a) mixing 30-50 parts by weight of the LBP and 50-70 parts by weight of polytetramethylene ether glycol (PTMEG), and dehydrating under reduced pressure at 48-52° C. for 2 hours; (b) cooling to room temperature, adding isophorone diisocyanate IPDI in an amount such that the [NCO] / [OH] molar ratio is 1.03-1.07, and reacting at 58-62° C. for 2-3 hours to obtain a prepolymer; (c) adding 8-12 parts by weight of the ADE and 4-6 parts by weight of the PNSFR to the prepolymer, and stirring at 68-72° C. for 30-60 minutes; (d) adding 0.05-0.15 parts by weight of dibutyltin dilaurate, stirring for 5-10 minutes, and vacuum degassing for 10-15 minutes; (e) injecting the degassed reaction solution into a mold preheated to 80° C. and curing at 78-82° C. for 24 hours; (f) The cured material was post-treated at room temperature for 48 hours.

2. The method according to claim 1, characterized in that: The lignin is industrial-grade alkali lignin, having a hydroxyl value of 200-250 mg KOH / g and an average molecular weight of 2000-3000 g / mol.

3. The method according to claim 1, characterized in that The LBP has a hydroxyl value of 350-450 mg KOH / g, an average molecular weight of 2500-3500 g / mol, and a hydroxyl functionality of 4-6.

4. The method according to claim 1, characterized in that The ADE has a melting point of 150-160° C., an amino content of 7.5-8.5 mmol / g, and an ultraviolet absorption peak of 320-340 nm.

5. The method according to claim 1, characterized in that The PNSFR has a phosphorus content of 8-10 wt %, a nitrogen content of 12-15 wt %, an epoxy value of 0.2-0.3 eq / 100 g, and a softening point of 90-100° C.

6. The method according to claim 1, characterized in that The PTMEG has a number average molecular weight of 2000±100 g / mol and a hydroxyl value of 56±2 mg KOH / g.

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