A castor oil-based flame retardant microcellular polyurethane elastomer and a method of making the same
By introducing DOPO and hydroxyl-terminated organosilicon chain extenders into castor oil-based microporous polyurethane elastomers, the problem of spontaneous combustion of microporous polyurethane elastomers has been solved, achieving high-efficiency flame retardancy and improved mechanical properties, making them suitable for automobiles, sporting goods and other fields.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INST OF CHEM IND OF FOREST PROD CHINESE ACAD OF FORESTRY
- Filing Date
- 2023-11-08
- Publication Date
- 2026-06-16
AI Technical Summary
Existing microporous polyurethane elastomers are prone to spontaneous combustion and have low flame retardant efficiency, which limits their application scenarios.
Flame-retardant microporous polyurethane elastomers were prepared by introducing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) into castor oil-based microporous polyurethane elastomers and using it in combination with hydroxyl-terminated organosilicon chain extenders.
This improves the flame retardant and mechanical properties of polyurethane elastomers, enhances their shock absorption capabilities, and meets the requirements of green and sustainable development.
Smart Images
Figure CN117402312B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polyurethane materials, specifically relating to a castor oil-based flame-retardant microporous polyurethane elastomer and its preparation method. Background Technology
[0002] Microporous polyurethane elastomers are a special type of polyurethane foam material. They are characterized by very small pore sizes; unlike elastomers, they are neither smooth, dense, and bubble-free, nor do they have the clearly visible and densely packed pores of other foam materials. The pore size ranges from 0.1 micrometers to hundreds of micrometers. These pores play a significant toughening role in the material. By increasing the number of pores and adjusting their size, microporous polyurethane elastomers can effectively dissipate external impacts and reduce energy transfer, thereby absorbing and mitigating impact forces and vibrations. This makes them ideal materials in many fields, such as automotive manufacturing, sporting goods, and protective housings for electronic devices. However, microporous polyurethane elastomers are highly flammable, easily causing personal injury and property damage. Therefore, improving the flame-retardant properties of microporous polyurethane materials is of great significance for expanding their application scenarios.
[0003] Phosphaphenanthrene flame retardants are an important area of current development. Currently, commercially available phosphaphenanthrene flame retardants include 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and its derivatives. Due to their unique molecular structure, these phosphaphenanthrene flame retardants exhibit better thermal and chemical stability than typical non-cyclic organophosphates. DOPO is a flame retardant intermediate that can react with olefins, epoxy groups, and carbonyl groups to prepare flame retardants suitable for various polymer materials, such as DOPO-HQ, DOPO-MA, and DOPO-ITA. These are widely used in the flame retardant treatment of polyesters, polyamides, epoxy resins, polyurethanes, and other polymer materials. However, because the DOPO molecule contains only one phosphorus element, its low flame-retardant content results in drawbacks such as low flame-retardant efficiency. Summary of the Invention
[0004] To address the aforementioned problems in the existing technology, the present invention aims to provide a castor oil-based flame-retardant microporous polyurethane elastomer and its preparation method.
[0005] To solve the above problems, the technical solution adopted by the present invention is as follows:
[0006] A method for preparing a castor oil-based flame-retardant microporous polyurethane elastomer includes the following steps:
[0007] (1) Castor oil, formic acid and hydrogen peroxide undergo epoxidation reaction under the action of catalyst A, and the resulting product is separated and purified to obtain epoxidized castor oil;
[0008] (2) Epoxidized castor oil and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were subjected to a ring-opening reaction under the action of catalyst B to obtain a flame-retardant polyol of castor oil.
[0009] (3) After removing the water from the castor oil flame retardant polyol, mix it with polyether or polyester polyol, isocyanate, foaming agent, chain extender, foam leveling agent and catalyst and other additives, pour it into a mold, and cure it to obtain flame retardant microporous polyurethane elastomer.
[0010] The chain extender consists of 10-20 wt% of a dihydroxy-terminated organosilicon chain extender and a small molecule polyol chain extender.
[0011] Optionally, in step (3), the total amount of polyol is 100 parts by weight, the foaming agent is 3-8 parts, the catalyst is 0.1-0.6 parts, the foaming agent is 0.1-0.5 parts, the chain extender is 1-1.6 parts, and the isocyanate is 80-130 parts, wherein the amount of castor oil flame retardant polyol in the polyol is 3-6 times that of polyether or polyester polyol.
[0012] Optionally, the epoxidation reaction conditions in step (1) are to keep the temperature at 40-50℃ for 2.5-3.5 h, and then raise the temperature to 60-70℃ for 3-4 h.
[0013] Optionally, the molar ratio of castor oil double bond: formic acid: hydrogen peroxide in step (1) is 1:(0.35-0.45):(1.35-1.55).
[0014] Optionally, catalyst A can be concentrated sulfuric acid, phosphoric acid, or p-toluenesulfonic acid.
[0015] Optionally, the ring-opening reaction in step (2) is carried out at a reaction temperature of 140-160 °C for 4-8 h.
[0016] Optionally, in step (2), the mass ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to epoxidized castor oil is (15-25):100.
[0017] Optionally, catalyst B is triphenylphosphine, and the amount of catalyst B added is 1%-3% of the mass of epoxidized castor oil.
[0018] Optionally, the polyether or polyester polyol is polycaprolactone diol, polytetrahydrofuran ether diol, or polypropylene glycol; the isocyanate is MDI, HDI, or IPDI; the small molecule polyol chain extender is 1,4-butanediol, ethylene glycol, glycerol, or propylene glycol; and the catalyst is an organotin catalyst or an amine catalyst.
[0019] The castor oil-based flame-retardant microporous polyurethane elastomer obtained according to the above method.
[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0021] In the synthesis of castor oil flame-retardant polyols, the flame-retardant small molecule 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is introduced through epoxidation and ring-opening, endowing microporous polyurethane elastomers with unique flexible chain segments, thus improving the mechanical properties and toughness of the elastomers. Simultaneously, the synthesized elastomers have smaller pore sizes, providing superior shock absorption capabilities. Using castor oil flame-retardant polyols grafted with DOPO in the preparation of polyurethane elastomers, and replacing some conventional chain extenders with partially hydroxyl-terminated organosilicon chain extenders, the polyurethane elastomers prepared through the synergistic effect of the hydroxyl-terminated organosilicon chain extenders and castor oil flame-retardant polyols in a certain proportion exhibit excellent flame-retardant and mechanical properties, as well as good resilience. Furthermore, the preparation of flame-retardant microporous polyurethane elastomers using vegetable oils is simple, low-cost, and aligns with the requirements of green and sustainable development. Attached Figure Description
[0022] Figure 1 The infrared spectrum of the flame-retardant castor oil polyol of the present invention is shown below. Detailed Implementation
[0023] The present invention will be further described below with reference to specific embodiments.
[0024] The organosilicon chain extender with a molecular weight of 92, specifically α-hydro-ω-hydroxy-polydimethylsiloxane, is selected for the dihydroxy-terminated organosilicon.
[0025] Example 1
[0026] Castor oil, formic acid, and the catalyst p-toluenesulfonic acid were mixed thoroughly, and hydrogen peroxide was slowly added dropwise. The molar ratio of castor oil:formic acid:hydrogen peroxide was 1:0.4:1.4, and the catalyst accounted for 3% of the total reactants. After the addition was complete, the mixture was kept at 40 °C for 3 h, and then the temperature was increased to 60 °C for another 3 h. After the reaction was complete, the product was dissolved in ethyl acetate, washed with saturated sodium bicarbonate and deionized water until the pH was neutral, and the organic phase was collected. The phase was then dehydrated with saturated sodium sulfate, filtered, and rotary evaporated to obtain epoxidized castor oil.
[0027] By weight, 100 parts of epoxidized castor oil and 20 parts of DOPO were mixed and stirred, and triphenylphosphine (2% by weight of epoxidized castor oil) was added. The mixture was reacted at 150 °C for 6 h. After removing water by vacuum distillation at 100 °C, the product was obtained as a castor oil flame-retardant polyol. The infrared spectrum of the castor oil flame-retardant polyol is shown below. Figure 1 .
[0028] By weight, 80 parts of castor oil flame-retardant polyol and 20 parts of polytetrahydrofuran-2000 are mixed evenly, then mixed with 5 parts of AK158 foaming agent, 0.4 parts of dibutyltin dilaurate catalyst, 0.3 parts of cyclopentane foaming agent, 0.24 parts of α-hydro-ω-hydroxy-polydimethylsiloxane and 1.26 parts of 1,4-butanediol. Finally, 110 parts of MDI-100 are added and stirred for 8 seconds at a speed of 2000 r / min. The mixture is poured into a mold and cured at 60 ℃ for one day, then cured in air for three days to obtain castor oil-based flame-retardant microporous polyurethane elastomer.
[0029] Example 2
[0030] Castor oil, formic acid, and the catalyst p-toluenesulfonic acid were mixed thoroughly, and then hydrogen peroxide was slowly added dropwise. The molar ratio of castor oil:formic acid:hydrogen peroxide was 1:0.45:1.35, and the catalyst accounted for 3% of the total reactants. After the addition was complete, the mixture was kept at 45°C for 2 hours, and then the temperature was increased to 70°C for 3.5 hours. After the reaction was complete, the product was dissolved in ethyl acetate, washed with saturated sodium bicarbonate and deionized water until the pH was neutral, and the organic phase was collected. The organic phase was dehydrated with saturated sodium sulfate, filtered, and rotary evaporated to obtain epoxidized castor oil.
[0031] By weight, 100 parts of epoxidized castor oil and 18 parts of DOPO were mixed and stirred, and triphenylphosphine (2% of the weight of epoxidized castor oil) was added. The mixture was reacted at a reaction temperature of 140 °C for 8 h. After the product was dehydrated by vacuum distillation at 100 °C, the flame-retardant polyol of castor oil was obtained.
[0032] By weight, 80 parts of castor oil flame-retardant polyol and 20 parts of polycaprolactone diol-2000 are mixed evenly, then mixed with 3 parts of AK158 foaming agent, 0.1 parts of dibutyltin dilaurate catalyst, 0.1 parts of HCFC-141b foaming agent, 0.18 parts of α-hydro-ω-hydroxy-polydimethylsiloxane and 1.02 parts of 1,4-butanediol. Finally, 100 parts of HDI are added and stirred for 8 seconds at a speed of 2000 r / min. The mixture is poured into a mold and cured at 60 ℃ for one day, then cured in air for three days to obtain castor oil-based flame-retardant microporous polyurethane elastomer.
[0033] Example 3
[0034] Castor oil, formic acid, and concentrated sulfuric acid (as a catalyst) were mixed thoroughly. Hydrogen peroxide was then slowly added dropwise. The molar ratio of castor oil to formic acid to hydrogen peroxide was 1:0.4:1.55, and the catalyst accounted for 3% of the total reactants. After the addition was complete, the mixture was kept at 50°C for 2.5 hours, then heated to 65°C for another 3 hours. The product was dissolved in ethyl acetate and washed with saturated sodium bicarbonate and deionized water until the pH was neutral. The organic phase was collected, dehydrated with saturated sodium sulfate, filtered, and rotary evaporated to obtain epoxidized castor oil.
[0035] By weight, 100 parts of epoxidized castor oil and 25 parts of DOPO were mixed and stirred, and triphenylphosphine (3% of the weight of epoxidized castor oil) was added. The mixture was reacted at a reaction temperature of 150 °C for 4 h. After the product was dehydrated by vacuum distillation at 100 °C, the flame-retardant polyol of castor oil was obtained.
[0036] By weight, 75 parts of castor oil flame-retardant polyol and 25 parts of polyether 330N-5000 are mixed evenly, then mixed with 6 parts of H-963 foaming agent, 0.4 parts of stannous octoate catalyst, 0.5 parts of cyclopentane foaming agent, 0.20 parts of α-hydro-ω-hydroxy-polydimethylsiloxane and 0.8 parts of 1,4-butanediol. Finally, 80 parts of MDI-50 are added and stirred for 8 seconds at a speed of 2000 r / min. The mixture is poured into a mold and cured at 60 ℃ for one day, then cured in air for three days to obtain castor oil-based flame-retardant microporous polyurethane elastomer.
[0037] Example 4
[0038] Castor oil, formic acid, and phosphoric acid catalyst were mixed thoroughly, and hydrogen peroxide was slowly added dropwise. The molar ratio of castor oil:formic acid:hydrogen peroxide was 1:0.35:1.4, and the catalyst accounted for 3% of the total reactants. After the addition was complete, the mixture was kept at 40 °C for 3 h, and then the temperature was increased to 65 °C for 3.5 h. After the reaction was complete, the product was dissolved in ethyl acetate, washed with saturated sodium bicarbonate and deionized water until the pH was neutral, the organic phase was collected, dehydrated with saturated sodium sulfate, filtered, and rotary evaporated to obtain epoxidized castor oil.
[0039] By weight, 100 parts of epoxidized castor oil and 15 parts of DOPO were mixed and stirred, and triphenylphosphine (1.5% of the weight of epoxidized castor oil) was added. The mixture was reacted at a reaction temperature of 160 °C for 7 h. After the product was dehydrated by vacuum distillation at 100 °C, the flame-retardant polyol of castor oil was obtained.
[0040] By weight, 85 parts of castor oil flame-retardant polyol and 15 parts of polytetrahydrofuran-2000 are mixed evenly, then mixed with 8 parts of AK158 foaming agent, 0.6 parts of dibutyltin dilaurate catalyst, 0.1 parts of cyclopentane foaming agent, 0.14 parts of α-hydro-ω-hydroxy-polydimethylsiloxane and 1.26 parts of propylene glycol. Finally, 130 parts of IPDI are added and stirred for 8 seconds at a speed of 2000 r / min. The mixture is poured into a mold and cured at 60 ℃ for one day, then cured in air for three days to obtain castor oil-based flame-retardant microporous polyurethane elastomer.
[0041] Comparative Example 1
[0042] Castor oil, formic acid, and the catalyst p-toluenesulfonic acid were mixed thoroughly, and hydrogen peroxide was slowly added dropwise. The molar ratio of castor oil:formic acid:hydrogen peroxide was 1:0.4:1.4, and the catalyst accounted for 3% of the total reactants. After the addition was complete, the mixture was kept at 40 °C for 3 h, and then the temperature was increased to 60 °C for another 3 h. After the reaction was complete, the product was dissolved in ethyl acetate, washed with saturated sodium bicarbonate and deionized water until the pH was neutral, and the organic phase was collected. The phase was then dehydrated with saturated sodium sulfate, filtered, and rotary evaporated to obtain epoxidized castor oil.
[0043] By weight, 100 parts of epoxidized castor oil and 20 parts of DOPO were mixed and stirred, and triphenylphosphine (2% of the weight of epoxidized castor oil) was added. The mixture was reacted at a reaction temperature of 150 °C for 6 h. After the product was dehydrated by vacuum distillation at 100 °C, the flame-retardant polyol of castor oil was obtained.
[0044] By weight, 80 parts of castor oil flame-retardant polyol and 20 parts of polytetrahydrofuran-2000 are mixed evenly, then mixed with 5 parts of AK158 foaming agent, 0.4 parts of dibutyltin dilaurate catalyst, 0.3 parts of cyclopentane foaming agent, and 1.5 parts of 1,4-butanediol. Finally, 110 parts of MDI-100 are added and stirred for 8 seconds at a speed of 2000 r / min. The mixture is poured into a mold and cured at 60 ℃ for one day, then cured in air for three days to obtain castor oil-based flame-retardant microporous polyurethane elastomer.
[0045] Comparative Example 2
[0046] Castor oil, formic acid, and the catalyst p-toluenesulfonic acid were mixed thoroughly, and hydrogen peroxide was slowly added dropwise. The molar ratio of castor oil:formic acid:hydrogen peroxide was 1:0.4:1.4, and the catalyst accounted for 3% of the total reactants. After the addition was complete, the mixture was kept at 40 °C for 3 h, and then the temperature was increased to 60 °C for another 3 h. After the reaction was complete, the product was dissolved in ethyl acetate, washed with saturated sodium bicarbonate and deionized water until the pH was neutral, and the organic phase was collected. The phase was then dehydrated with saturated sodium sulfate, filtered, and rotary evaporated to obtain epoxidized castor oil.
[0047] By weight, 100 parts of epoxidized castor oil and 20 parts of DOPO were mixed and stirred, and triphenylphosphine (2% of the weight of epoxidized castor oil) was added. The mixture was reacted at a reaction temperature of 150 °C for 6 h. After the product was dehydrated by vacuum distillation at 100 °C, the flame-retardant polyol of castor oil was obtained.
[0048] By weight, 80 parts of castor oil flame-retardant polyol and 20 parts of polytetrahydrofuran-2000 are mixed evenly, then mixed with 5 parts of AK158 foaming agent, 0.4 parts of dibutyltin dilaurate catalyst, 0.3 parts of cyclopentane foaming agent, 0.24 parts of polydimethylsiloxane (methyl-terminated, molecular weight 1000) and 1.5 parts of 1,4-butanediol. Finally, 110 parts of MDI-100 are added and stirred for 8 seconds at a speed of 2000 r / min. The mixture is poured into a mold and cured at 60 ℃ for one day, then cured in air for three days to obtain castor oil-based flame-retardant microporous polyurethane elastomer.
[0049] Comparative Example 3
[0050] By weight, 100 parts castor oil and 20 parts DOPO were mixed and stirred, and a double bond addition reaction was carried out at a reaction temperature of 150°C for 6 h. After the product was dehydrated by vacuum distillation at 100°C, modified castor oil was obtained.
[0051] By weight, 80 parts of modified castor oil and 20 parts of polytetrahydrofuran-2000 are mixed evenly, then mixed with 5 parts of AK158 foaming agent, 0.4 parts of dibutyltin dilaurate catalyst, 0.3 parts of cyclopentane foaming agent, 0.24 parts of α-hydro-ω-hydroxy-polydimethylsiloxane and 1.26 parts of 1,4-butanediol. Finally, 110 parts of MDI-100 are added and stirred for 8 seconds at a speed of 2000 r / min. The mixture is poured into a mold and cured at 60 ℃ for one day, then cured in air for three days to obtain castor oil-based flame-retardant microporous polyurethane elastomer.
[0052] Comparative Example 4
[0053] Castor oil, formic acid, and the catalyst p-toluenesulfonic acid were mixed thoroughly, and hydrogen peroxide was slowly added dropwise. The molar ratio of castor oil:formic acid:hydrogen peroxide was 1:0.4:1.4, and the catalyst accounted for 3% of the total reactants. After the addition was complete, the mixture was kept at 40 °C for 3 h, and then the temperature was increased to 60 °C for another 3 h. After the reaction was complete, the product was dissolved in ethyl acetate, washed with saturated sodium bicarbonate and deionized water until the pH was neutral, and the organic phase was collected. The phase was then dehydrated with saturated sodium sulfate, filtered, and rotary evaporated to obtain epoxidized castor oil.
[0054] By weight, 100 parts of epoxidized castor oil and 30 parts of DOPO were mixed and stirred, and triphenylphosphine (2% of the weight of epoxidized castor oil) was added. The mixture was reacted at a reaction temperature of 150 °C for 6 h. After the product was dehydrated by vacuum distillation at 100 °C, the flame-retardant polyol of castor oil was obtained.
[0055] By weight, 80 parts of castor oil flame-retardant polyol and 20 parts of polytetrahydrofuran-2000 are mixed evenly, then mixed with 5 parts of AK158 foaming agent, 0.4 parts of dibutyltin dilaurate catalyst, 0.3 parts of cyclopentane foaming agent, 0.6 parts of α-hydro-ω-hydroxy-polydimethylsiloxane and 0.9 parts of 1,4-butanediol. Finally, 110 parts of MDI-100 are added and stirred for 8 seconds at a speed of 2000 r / min. The mixture is poured into a mold and cured at 60 ℃ for one day, then cured in air for three days to obtain castor oil-based flame-retardant microporous polyurethane elastomer.
[0056] The flame retardant and mechanical properties of the castor oil-based flame-retardant microporous polyurethane elastomers obtained in Examples 1-4 and Comparative Examples 1-4 were tested. The test results are shown in Table 1. The limiting oxygen index was determined according to GB / T2406-2008.
[0057] Table 1. Performance test results of castor oil-based flame-retardant microporous polyurethane elastomers
[0058]
[0059] As can be seen from the results in Table 1, the polyurethane elastomer prepared by this invention has excellent flame retardant and mechanical properties. By using castor oil flame retardant polyol grafted with DOPO and hydroxyl-terminated organosilicon chain extender in a certain proportion, the limiting oxygen index of the castor oil-based flame retardant microporous polyurethane elastomer can reach more than 28%, the resilience rate is maintained at about 85%, and good tensile strength is maintained.
Claims
1. A method for preparing a castor oil-based flame-retardant microporous polyurethane elastomer, characterized in that, Includes the following steps: (1) Castor oil, formic acid and hydrogen peroxide undergo epoxidation reaction under the action of catalyst A, and the resulting product is separated and purified to obtain epoxidized castor oil; (2) Epoxidized castor oil and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were subjected to a ring-opening reaction under the action of catalyst B to obtain a flame-retardant polyol of castor oil. (3) After removing the water from the castor oil flame retardant polyol, mix it with polyether or polyester polyol, isocyanate, foaming agent, chain extender, foam leveling agent and catalyst, pour it into a mold, and cure it to obtain flame retardant microporous polyurethane elastomer. The chain extender is composed of 10-20 wt% of a dihydroxy-terminated organosilicon chain extender and a small molecule polyol chain extender; In step (2), the mass ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to epoxidized castor oil is (15-25):
100.
2. The method for preparing a castor oil-based flame-retardant microporous polyurethane elastomer according to claim 1, characterized in that, In step (3), the total amount of polyol is 100 parts by weight, the foaming agent is 3-8 parts, the catalyst is 0.1-0.6 parts, the foaming agent is 0.1-0.5 parts, the chain extender is 1-1.6 parts, and the isocyanate is 80-130 parts. Among them, the amount of castor oil flame retardant polyol is 3-6 times that of polyether or polyester polyol.
3. The method for preparing a castor oil-based flame-retardant microporous polyurethane elastomer according to claim 1, characterized in that, The epoxidation reaction conditions in step (1) are to keep the temperature at 40-50℃ for 2.5-3.5 h, and then raise the temperature to 60-70℃ for 3-4 h.
4. The method for preparing a castor oil-based flame-retardant microporous polyurethane elastomer according to claim 1, characterized in that, The molar ratio of castor oil double bond: formic acid: hydrogen peroxide in step (1) is 1:(0.35-0.45):(1.35-1.55).
5. The method for preparing a castor oil-based flame-retardant microporous polyurethane elastomer according to claim 1, characterized in that, Catalyst A consists of concentrated sulfuric acid, phosphoric acid, and p-toluenesulfonic acid.
6. The method for preparing a castor oil-based flame-retardant microporous polyurethane elastomer according to claim 1, characterized in that, Step (2) The ring-opening reaction conditions are a reaction temperature of 140-160 °C for 4-8 h.
7. The method for preparing a castor oil-based flame-retardant microporous polyurethane elastomer according to claim 1, characterized in that, Catalyst B is triphenylphosphine, and the amount of catalyst B added is 1%-3% of the mass of epoxidized castor oil.
8. The method for preparing a castor oil-based flame-retardant microporous polyurethane elastomer according to claim 1, characterized in that, The polyether or polyester polyol is polycaprolactone diol, polytetrahydrofuran ether diol, or polypropylene glycol; the isocyanate is MDI, HDI, or IPDI; the small molecule polyol chain extender is 1,4-butanediol, ethylene glycol, glycerol, or propylene glycol; and the catalyst is an organotin catalyst or an amine catalyst.
9. The castor oil-based flame-retardant microporous polyurethane elastomer obtained by the method according to any one of claims 1-8.