A preparation method and application of bio-based polyester polyol

Abstract

The invention discloses a preparation method and application of a bio-based polyester polyol, and belongs to the technical field of polymer preparation. The preparation method of the bio-based polyester polyol comprises the following steps: step (1): adding castor oil, a catalyst and glycerol to a reactor, heating and reacting to obtain a composite castor oil; step (2): adding a mixture of composite castor oil, formic acid, phosphoric acid and a resin additive to a container, dripping hydrogen peroxide, heating and stirring to react after the dripping is completed, and then obtaining epoxy composite castor oil; step (3): adding epoxy composite castor oil and toluene to a container, heating and reacting, then dripping a mixture of toluene diphenyl phosphate, toluene and triphenylphosphine, heating and stirring to react, and obtaining a bio-based polyester polyol. The bio-based polyester polyol prepared by the method has excellent flame retardant properties and environmental protection, and its application in the preparation process of polyurethane materials can effectively reduce carbon emissions.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer preparation, and specifically relates to a preparation method of bio-based polyester polyol and application thereof. Background Art

[0002] With the rapid development of industrialization, the pressure on the environment caused by traditional petroleum-based polyurethane materials during production and use is increasing, and the rise of bio-based polyester polyols provides an important way for the green transformation of polyurethane materials. Through advanced chemical conversion technology, polyester polyols with excellent performance are prepared, which not only reduces dependence on fossil resources, but also reduces carbon emissions, which is in line with the global trend of energy conservation and emission reduction. In the preparation process of this material, through biological fermentation, chemical synthesis and other means, the transformation from renewable resources to high-performance materials is realized, laying a solid foundation for the sustainable development of polyurethane materials. In addition, polyurethane materials are widely used in many fields due to their excellent physical properties, chemical stability and processing properties. As one of the raw materials of polyurethane, bio-based polyester polyols not only retain these advantages of polyurethane materials, but also give them better biocompatibility and degradability. This makes bio-based polyurethane materials have broader application prospects in the fields of medical care, food packaging, and environmentally friendly homes.

[0003] Patent CN 117946376 A discloses a method for preparing a bio-based polyester polyol, comprising the following steps: subjecting a mixture containing an inorganic oxygen-containing acid ester and a bio-based polyol to an ester exchange reaction under the action of a catalyst to obtain the bio-based polyester polyol. The method uses an inorganic oxygen-containing acid ester and a bio-based polyol as raw materials to carry out an ester exchange reaction to obtain a bio-based polyester polyol polymer, which replaces traditional petroleum-based raw materials and is environmentally friendly. The product prepared by the method has good heat resistance, but its flame retardancy and environmental protection still have room for improvement. Summary of the invention

[0004] The object of the present invention is to provide a preparation method of a bio-based polyester polyol and application thereof, so as to solve the technical problems of poor flame retardancy and environmental protection of the bio-based polyester polyol in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for preparing a bio-based polyester polyol, comprising the following steps:

[0007] Step (1): adding castor oil and a catalyst into a reaction kettle, heating to a reaction temperature, introducing nitrogen, then adding glycerol into the reaction kettle, heating for reaction, cooling, and washing to obtain composite castor oil;

[0008] Step (2): mixing composite castor oil, formic acid, phosphoric acid and resin additive, adding the mixture into a container, heating in a water bath, then dripping hydrogen peroxide, controlling the dripping time, heating and stirring to react after the dripping is completed, then cooling, washing and drying to obtain epoxy composite castor oil;

[0009] Step (3): adding epoxy composite castor oil and toluene into a container, heating for reaction, then dropping a mixture of toluene diphenyl phosphate, toluene and triphenylphosphine, after the dropping is completed, heating and stirring for reaction, cooling, adjusting the pH, washing, and drying to obtain a bio-based polyester polyol.

[0010] In the above process, castor oil and propylene glycol undergo an ester exchange reaction under the catalysis of a catalyst to obtain a composite castor oil. The composite castor oil is then mixed with formic acid, phosphoric acid and a resin additive, and then an oxidation reaction is carried out by adding hydrogen peroxide. Under acidic conditions, hydrogen peroxide can oxidize the double bonds in the composite castor oil molecules to generate epoxy groups to obtain epoxy composite castor oil. Subsequently, the epoxy composite castor oil reacts with toluene diphenyl phosphate in a toluene solvent, and the reaction is promoted by adding triphenylphosphine. The epoxy group is ring-opened and reacts with toluene diphenyl phosphate to form a polyester chain to obtain a bio-based polyester polyol.

[0011] Preferably, in the step (1), the ratio of castor oil, catalyst and glycerol is (523.6-1047.2) mL: (3.75-7.5) g: (98.64-197.28) mL, the reaction temperature is 180-200° C., the nitrogen introduction time is 30-40 min, the heating reaction temperature is 170-190° C., the time is 3-5 h, the cooling temperature is 35-40° C., and the mixture is washed with distilled water 3-5 times.

[0012] Preferably, in step (1), the catalyst is one or more combinations of sodium hydroxide, potassium hydroxide, sodium methoxide and triethanolamine.

[0013] Preferably, in the step (2), the ratio of the composite castor oil, formic acid, phosphoric acid, resin additive and hydrogen peroxide is (100-120) g: (6.35-7.62) mL: (0.15-0.18) mL: (0.1-0.12) g: (0.25-0.28) mL, the water bath heating temperature is 40-50° C., the dropwise addition time is 30-45 min, the heating and stirring reaction temperature is 60-65° C., the time is 6-8 h, and washing is performed with 1 mol / L sodium hydroxide until the pH is 7.

[0014] Preferably, the method for preparing the resin additive comprises the following steps:

[0015] S1: adding gelatin to a container filled with deionized water, mixing evenly, reacting, then adding cellulose to the container, stirring to dissolve, adjusting the pH, then adding a mixture of glyceryl methacrylate, benzoyl peroxide and divinylbenzene, stirring, heating to react, continuing to heat to react, cooling after the reaction is completed, filtering, washing, and drying to obtain resin microspheres;

[0016] S2: Add sodium aminosulfonate to a container containing deionized water, and then add a swelling agent to obtain a mixture, add resin microspheres under heating conditions, react, and after the reaction is completed, cool, filter, wash, and dry to obtain a resin additive.

[0017] In the above process, the free radicals generated by the decomposition of benzoyl peroxide initiate the polymerization reaction of glycerol methacrylate and divinylbenzene to obtain resin microspheres, which are then grafted with sodium aminosulfonate to obtain resin additives.

[0018] Preferably, in S1, the amount ratio of gelatin, deionized water and cellulose is (5-7.5) g: (10-20) mL: (3-5) g, the reaction time is 10-20 min, the stirring and dissolving time is 15-25 min, the pH is adjusted to 7-7.2, the molar ratio of glycerol methacrylate, benzoyl peroxide and divinylbenzene is (2-3): (0.2-0.3): (1-1.4), the stirring rate is 90-100 rpm, the heating reaction temperature is 80-85°C, the time is 2-3h, the heating reaction temperature is continued to be 90-95°C, the time is 2-4h, the filter is filtered with a Buchner funnel, washed with deionized water at 65-80°C, and the drying temperature is 80-90°C for 10-12h.

[0019] Preferably, in S2, the dosage ratio of sodium aminosulfonate, deionized water, swelling agent and resin microspheres is (10-18) mL: (50-80) mL: (1-1.5) mL: (15-20) g, the heating temperature is 70-100°C, the pH value during the heating process is 8-10, the reaction time is 15-20h, the product is filtered with a Buchner funnel, washed with deionized water at 65-80°C, and the drying temperature is 80-85°C for 10-12h.

[0020] Preferably, in S2, the swelling agent is one or more combinations of dimethyl sulfoxide, dichloroethane, dimethylamide and acetone.

[0021] Preferably, in the step (3), the usage ratio of epoxy composite castor oil, toluene diphenyl phosphate and triphenylphosphine is (100-120) g: (40-48) mL: (0.5-0.6) g, the heating reaction temperature is 40-60° C., the dropwise addition time is 30-45 min, the heating and stirring reaction temperature is 70-75° C., the reaction time is 4-6 h, the pH is adjusted to 7-7.5 with 1 mol / L sodium hydroxide solution, and the mixture is washed with distilled water 3-5 times.

[0022] A method for applying bio-based polyester polyol, which applies the bio-based polyester polyol to synthesizing polyurethane hot melt adhesive.

[0023] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0024] 1. In the present invention, castor oil, glycerol and toluene diphenyl phosphate are used as raw materials to prepare bio-based polyester polyols. During the preparation process, a resin additive prepared by using gelatin, cellulose, glycerol methacrylate, benzoyl peroxide, divinylbenzene and sodium aminosulfonate as raw materials is added. The prepared bio-based polyester polyol is used in the synthesis process of polyurethane hot melt adhesive by this method, which can effectively improve the flame retardancy and environmental protection of the hot melt adhesive and reduce the carbon content in the preparation process.

[0025] 2. The present invention uses gelatin, cellulose, glycerol methacrylate, benzoyl peroxide, divinylbenzene and sodium aminosulfonate as raw materials to prepare a resin additive, which is applied to the process of preparing epoxy composite castor oil from composite castor oil, and can effectively improve the catalytic efficiency. The sulfonic acid group on the surface of the resin additive serves as a proton source, which can provide protons to the reaction system and promote the protonation of unsaturated bonds in castor oil. The protonated unsaturated bonds are susceptible to oxygen attack, initiating epoxidation reaction, and the three-dimensional network structure of the resin provides a rich reaction interface and microenvironment, which is beneficial to the diffusion and contact of reactant molecules, further improving the catalytic efficiency. Compared with traditional catalysts, the resin additive is easy to recycle and reuse, which reduces the consumption of catalysts and the generation of waste, simplifies the production process, and reduces production costs.

[0026] 3. In the present invention, castor oil, propylene glycol and toluene diphenyl phosphate are used as raw materials to prepare bio-based polyester polyols. Using it as one of the raw materials for polyurethane hot melt adhesive can effectively improve the flame retardancy and environmental protection of polyurethane hot melt adhesive, and at the same time reduce carbon emissions. Toluene diphenyl phosphate is a phosphorus-containing flame retardant, and the phosphorus element contained in toluene diphenyl phosphate can play a flame retardant role during the combustion process. The carbonized layer formed at high temperature not only isolates oxygen, but also blocks the transfer of heat, and the flame retardant elements can be evenly distributed in the polyurethane molecular chain, so that the flame retardant effect is more durable and uniform, thereby improving the overall flame retardant performance of the polyurethane hot melt adhesive; the preparation process of bio-based polyester polyols reduces dependence on fossil resources, reduces greenhouse gas emissions, and due to the environmental protection of the raw materials, also reduces the release of harmful substances; using bio-based polyester polyols to replace traditional petroleum-based polyester polyols to prepare polyurethane hot melt adhesives can reduce dependence on fossil resources and promote the development of a low-carbon economy. DETAILED DESCRIPTION

[0027] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Embodiment 1: This embodiment provides a method for preparing a resin additive, comprising the following steps:

[0029] S1: Add 6.25g of gelatin to a container containing 15mL of deionized water, mix well, react for 15min, then add 4g of cellulose to the container, stir and dissolve for 25min, adjust pH=7, then add a mixture of 6.83mL of glycerol methacrylate, 1.25g of benzoyl peroxide and 3.23g of divinylbenzene, stir at 90rpm, heat at 85℃ for 2h, then continue to heat at 95℃ for 4h, after the reaction is completed, cool, filter with a Buchner funnel, wash with deionized water at 65℃, and dry at 80℃ for 12h to obtain resin microspheres;

[0030] S2: Add 14 mL of sodium aminosulfonate to a container containing 75 mL of deionized water, and then add 1.25 mL of dichloroethane to obtain a mixture. At 75°C and pH = 8, add 17.5 g of resin microspheres and react for 20 hours. After the reaction is completed, cool, filter with a Buchner funnel, wash with deionized water at 65°C, and dry at 85°C for 12 hours to obtain a resin additive.

[0031] This embodiment provides a method for preparing a bio-based polyester polyol, comprising the following steps:

[0032] Step (1): adding 785.4 mL of castor oil and 5.63 g of sodium hydroxide to a reaction kettle, heating to 200° C., introducing nitrogen for 30 min, then adding 147.96 mL of propylene glycol to the reaction kettle, heating at 180° C. for reaction for 5 h, cooling to 40° C., and washing with distilled water for 3 times to obtain composite castor oil;

[0033] Step (2): 110 g of composite castor oil, 6.99 mL of formic acid, 0.175 mL of phosphoric acid and 0.11 g of resin additive were mixed and added to a container, heated in a water bath at 40° C., and then 0.27 mL of hydrogen peroxide was added dropwise, and the addition time was controlled to be 30 min. After the addition was completed, the mixture was heated at 65° C. and stirred for reaction for 8 h, then cooled, washed with 1 mol / L of sodium hydroxide until pH=7, and dried to obtain epoxy composite castor oil;

[0034] Step (3): Add 110g epoxy composite castor oil and 40mL toluene into a container, heat to 60°C for reaction, then drop a mixture of 44mL toluene diphenyl phosphate, 75mL toluene and 0.55g triphenylphosphine, the dropping time is 30min, after the dropping is completed, heat and stir at 75°C for reaction for 6h, cool, adjust pH to 7 with 1mol / L sodium hydroxide solution, wash 5 times with distilled water, and dry to obtain bio-based polyester polyol.

[0035] Embodiment 2: This embodiment provides a method for preparing a resin additive, comprising the following steps:

[0036] S1: Add 5g of gelatin to a container containing 10mL of deionized water, mix well, react for 15min, then add 3g of cellulose to the container, stir and dissolve for 25min, adjust pH=7, then add a mixture of 5.46mL of glycerol methacrylate, 1g of benzoyl peroxide and 2.69g of divinylbenzene, stir at 90rpm, heat at 85℃ for 2h, then continue to heat at 95℃ for 4h, after the reaction is completed, cool, filter with a Buchner funnel, wash with deionized water at 65℃, and dry at 80℃ for 12h to obtain resin microspheres;

[0037] S2: Add 10 mL of sodium aminosulfonate to a container containing 50 mL of deionized water, and then add 1 mL of dichloroethane to obtain a mixture. At 75°C and pH = 8, add 15 g of resin microspheres and react for 20 hours. After the reaction is completed, cool, filter with a Buchner funnel, wash with deionized water at 65°C, and dry at 85°C for 12 hours to obtain a resin additive.

[0038] This embodiment provides a method for preparing a bio-based polyester polyol, comprising the following steps:

[0039] Step (1): 523.6 mL of castor oil and 3.75 g of sodium hydroxide were added to a reaction kettle, heated to 200° C., and nitrogen was introduced for 30 min. Then, 98.64 mL of propylene glycol was added to the reaction kettle, heated at 180° C. for 5 h, cooled to 40° C., and washed with distilled water for 3 times to obtain composite castor oil;

[0040] Step (2): 100 g of composite castor oil, 6.35 mL of formic acid, 0.15 mL of phosphoric acid and 0.12 g of a resin additive are mixed and added to a container, heated in a water bath at 40° C., and then 0.25 mL of hydrogen peroxide is added dropwise, and the dropping time is controlled to be 30 min. After the dropping is completed, the mixture is heated and stirred at 65° C. for 8 h, then cooled, washed with 1 mol / L of sodium hydroxide until the pH value is 7, and dried to obtain epoxy composite castor oil;

[0041] Step (3): Add 100g epoxy composite castor oil and 40mL toluene into a container, heat to 60°C for reaction, then drop a mixture of 40mL toluene diphenyl phosphate, 75mL toluene and 0.5g triphenylphosphine, the dropping time is 30min, after the dropping is completed, heat and stir at 75°C for reaction for 6h, cool, adjust pH to 7 with 1mol / L sodium hydroxide solution, wash 5 times with distilled water, and dry to obtain bio-based polyester polyol.

[0042] Embodiment 3: This embodiment provides a method for preparing a resin additive, comprising the following steps:

[0043] S1: 7.5 g of gelatin was added to a container containing 20 mL of deionized water, mixed evenly, reacted for 15 min, then 5 g of cellulose was added to the container, stirred and dissolved for 25 min, pH was adjusted to 7, and then a mixture of 8.19 mL of glycerol methacrylate, 1.5 g of benzoyl peroxide and 3.76 g of divinylbenzene was added, stirred at 90 rpm, heated at 85 ° C for 2 h, and then heated at 95 ° C for 4 h. After the reaction was completed, it was cooled, filtered with a Buchner funnel, washed with deionized water at 65 ° C, and dried at 80 ° C for 12 h to obtain resin microspheres;

[0044] S2: Add 18 mL of sodium aminosulfonate to a container containing 80 mL of deionized water, and then add 1.5 mL of dichloroethane to obtain a mixture. At 75°C and pH = 8, add 20 g of resin microspheres and react for 20 hours. After the reaction is completed, cool, filter with a Buchner funnel, wash with deionized water at 65°C, and dry at 85°C for 12 hours to obtain a resin additive.

[0045] This embodiment provides a method for preparing a bio-based polyester polyol, comprising the following steps:

[0046] Step (1): 1047.2 mL of castor oil and 7.5 g of sodium hydroxide were added to a reaction kettle, heated to 200° C., and nitrogen was introduced for 30 min. Subsequently, 197.28 mL of propylene glycol was added to the reaction kettle, heated at 180° C. for 5 h, cooled to 40° C., and washed with distilled water for 3 times to obtain composite castor oil;

[0047] Step (2): 120 g of composite castor oil, 7.62 mL of formic acid, 0.18 mL of phosphoric acid and 0.1 g of a resin additive are mixed and added to a container, heated in a water bath at 40° C., and then 0.28 mL of hydrogen peroxide is added dropwise, and the dropping time is controlled to be 30 min. After the dropping is completed, the mixture is heated and stirred at 65° C. for 8 h, and then cooled, washed with 1 mol / L of sodium hydroxide until the pH value is 7, and dried to obtain epoxy composite castor oil;

[0048] Step (3): Add 120g epoxy composite castor oil and 40mL toluene into a container, heat to 60°C for reaction, then drop a mixture of 48mL toluene diphenyl phosphate, 75mL toluene and 0.6g triphenylphosphine, the dropping time is 30min, after the dropping is completed, heat and stir at 75°C for reaction for 6h, cool, adjust pH to 7 with 1mol / L sodium hydroxide solution, wash 5 times with distilled water, and dry to obtain bio-based polyester polyol.

[0049] Embodiment 4: This embodiment provides a method for preparing a resin additive, comprising the following steps:

[0050] S1: Add 5.5g of gelatin to a container containing 12mL of deionized water, mix well, react for 15min, then add 3.5g of cellulose to the container, stir and dissolve for 25min, adjust pH=7, then add a mixture of 6.15mL of glycerol methacrylate, 1.1g of benzoyl peroxide and 2.96g of divinylbenzene, stir at 90rpm, heat at 85℃ for 2h, then continue to heat at 95℃ for 4h, after the reaction is completed, cool, filter with a Buchner funnel, wash with deionized water at 65℃, and dry at 80℃ for 12h to obtain resin microspheres;

[0051] S2: Add 12 mL of sodium aminosulfonate to a container containing 60 mL of deionized water, and then add 1.2 mL of dichloroethane to obtain a mixture. At 75°C and pH = 8, add 16 g of resin microspheres and react for 20 hours. After the reaction is completed, cool, filter with a Buchner funnel, wash with deionized water at 65°C, and dry at 85°C for 12 hours to obtain a resin additive.

[0052] This embodiment provides a method for preparing a bio-based polyester polyol, comprising the following steps:

[0053] Step (1): 654.5 mL of castor oil and 4.69 g of sodium hydroxide were added to a reaction kettle, heated to 200° C., and nitrogen was introduced for 30 min. Subsequently, 123.3 mL of propylene glycol was added to the reaction kettle, heated at 180° C. for 5 h, cooled to 40° C., and washed with distilled water for 3 times to obtain composite castor oil;

[0054] Step (2): 105 g of composite castor oil, 6.67 mL of formic acid, 0.16 mL of phosphoric acid and 0.11 g of a resin additive were mixed and added to a container, heated in a water bath at 40° C., and then 0.26 mL of hydrogen peroxide was added dropwise, and the addition time was controlled to be 30 min. After the addition was completed, the mixture was heated and stirred at 65° C. for 8 h, then cooled, washed with 1 mol / L of sodium hydroxide until the pH value was 7, and dried to obtain epoxy composite castor oil;

[0055] Step (3): Add 105g epoxy composite castor oil and 40mL toluene into a container, heat to 60°C for reaction, then drop a mixture of 42mL toluene diphenyl phosphate, 75mL toluene and 0.52g triphenylphosphine, the dropping time is 30min, after the dropping is completed, heat and stir at 75°C for reaction for 6h, cool, adjust pH to 7 with 1mol / L sodium hydroxide solution, wash 5 times with distilled water, and dry to obtain bio-based polyester polyol.

[0056] Embodiment 5: This embodiment provides a method for preparing a resin additive, comprising the following steps:

[0057] S1: 7 g of gelatin was added to a container containing 18 mL of deionized water, mixed evenly, reacted for 15 min, then 4.5 g of cellulose was added to the container, stirred and dissolved for 25 min, pH was adjusted to 7, and then a mixture of 7.51 mL of glycerol methacrylate, 1.4 g of benzoyl peroxide and 3.49 g of divinylbenzene was added, stirred at 90 rpm, heated at 85 ° C for 2 h, and then heated at 95 ° C for 4 h. After the reaction was completed, it was cooled, filtered with a Buchner funnel, washed with deionized water at 65 ° C, and dried at 80 ° C for 12 h to obtain resin microspheres;

[0058] S2: Add 16 mL of sodium aminosulfonate to a container containing 70 mL of deionized water, and then add 1.4 mL of dichloroethane to obtain a mixture. At 75°C and pH = 8, add 18 g of resin microspheres and react for 20 hours. After the reaction is completed, cool, filter with a Buchner funnel, wash with deionized water at 65°C, and dry at 85°C for 12 hours to obtain a resin additive.

[0059] This embodiment provides a method for preparing a bio-based polyester polyol, comprising the following steps:

[0060] Step (1): adding 916.3 mL of castor oil and 5.57 g of sodium hydroxide to a reaction kettle, heating to 200° C., introducing nitrogen for 30 min, then adding 172.62 mL of propylene glycol to the reaction kettle, heating at 180° C. for reaction for 5 h, cooling to 40° C., and washing with distilled water for 3 times to obtain composite castor oil;

[0061] Step (2): 115 g of composite castor oil, 7.31 mL of formic acid, 0.17 mL of phosphoric acid and 0.12 g of a resin additive were mixed and added to a container, heated in a water bath at 40° C., and then 0.255 mL of hydrogen peroxide was added dropwise, and the addition time was controlled to be 30 min. After the addition was completed, the mixture was heated at 65° C. and stirred for reaction for 8 h, then cooled, washed with 1 mol / L of sodium hydroxide until pH=7, and dried to obtain epoxy composite castor oil;

[0062] Step (3): Add 115g of epoxy composite castor oil and 40mL of toluene to a container, heat to 60°C for reaction, then drop a mixture of 46mL of toluene diphenyl phosphate, 75mL of toluene and 0.58g of triphenylphosphine, the dropping time is 30min, after the dropping is completed, heat and stir at 75°C for reaction for 6h, cool, adjust the pH to 7 with 1mol / L sodium hydroxide solution, wash with distilled water 5 times, and dry to obtain a bio-based polyester polyol.

[0063] Embodiment 6: This embodiment provides a method for preparing a resin additive, comprising the following steps:

[0064] S1: Add 7.2g of gelatin to a container containing 19mL of deionized water, mix well, react for 15min, then add 4.2g of cellulose to the container, stir and dissolve for 25min, adjust pH=7, then add a mixture of 6.23mL of glycerol methacrylate, 1.2g of benzoyl peroxide and 3.17g of divinylbenzene, stir at 90rpm, heat at 85℃ for 2h, then continue to heat at 95℃ for 4h, after the reaction is completed, cool, filter with a Buchner funnel, wash with deionized water at 65℃, and dry at 80℃ for 12h to obtain resin microspheres;

[0065] S2: Add 15 mL of sodium aminosulfonate to a container containing 72 mL of deionized water, and then add 1.15 mL of dichloroethane to obtain a mixture. At 75°C and pH = 8, add 17 g of resin microspheres and react for 20 hours. After the reaction is completed, cool, filter with a Buchner funnel, wash with deionized water at 65°C, and dry at 85°C for 12 hours to obtain a resin additive.

[0066] This embodiment provides a method for preparing a bio-based polyester polyol, comprising the following steps:

[0067] Step (1): 663.4 mL of castor oil and 4.17 g of sodium hydroxide were added to a reaction kettle, heated to 200° C., and nitrogen was introduced for 30 min. Subsequently, 183.85 mL of propylene glycol was added to the reaction kettle, heated at 180° C. for 5 h, cooled to 40° C., and washed with distilled water for 3 times to obtain composite castor oil;

[0068] Step (2): 101 g of composite castor oil, 6.87 mL of formic acid, 0.158 mL of phosphoric acid and 0.11 g of a resin additive were mixed and added to a container, heated in a water bath at 40° C., and then 0.27 mL of hydrogen peroxide was added dropwise, and the addition time was controlled to be 30 min. After the addition was completed, the mixture was heated at 65° C. and stirred for reaction for 8 h, then cooled, washed with 1 mol / L of sodium hydroxide until pH=7, and dried to obtain epoxy composite castor oil;

[0069] Step (3): Add 118g of epoxy composite castor oil and 40mL of toluene to a container, heat to 60°C for reaction, then drop a mixture of 45mL of toluene diphenyl phosphate, 75mL of toluene and 0.53g of triphenylphosphine, the dropping time is 30min, after the dropping is completed, heat and stir at 75°C for reaction for 6h, cool, adjust the pH to 7 with 1mol / L sodium hydroxide solution, wash with distilled water 5 times, and dry to obtain a bio-based polyester polyol.

[0070] Comparative Example 1: Compared with Example 1, in the process of preparing the resin additive in Comparative Example 1, glycerol methacrylate is not added, and other conditions remain unchanged.

[0071] Comparative Example 2: Compared with Example 1, in Comparative Example 2, during the preparation of the resin additive, sodium aminosulfonate was not added, and other conditions remained unchanged.

[0072] Comparative Example 3: Compared with Example 1, in Comparative Example 3, during the preparation of bio-based polyester polyol, toluene diphenyl phosphate was not added, and other conditions remained unchanged.

[0073] Experimental example

[0074] The samples prepared in Examples 1-6 and Comparative Examples 1-3 were subjected to performance tests, and the obtained samples were reacted with diisocyanate, chain extender and catalyst to obtain polyurethane materials. The combustion performance of the samples was tested according to GB / T 10707-2008. The test results are shown in Table 1:

[0075] Table 1

[0076]

[0077]

[0078] From the test results in Table 1, it can be seen that the bio-based polyester polyols prepared in Examples 1-6 of the present invention have excellent flame retardant properties. From the comparison between Comparative Example 3 and Examples 1-6, it can be seen that the addition of toluene diphenyl phosphate can effectively improve the flame retardant properties of polyurethane materials.

[0079] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0080] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a bio-based polyester polyol, characterized in that: The following steps are involved: Step (1): adding castor oil and a catalyst into a reaction kettle, heating to a reaction temperature, introducing nitrogen, then adding glycerol into the reaction kettle, heating for reaction, cooling, and washing to obtain composite castor oil; Step (2): mixing composite castor oil, formic acid, phosphoric acid and resin additive and adding them into a container, heating in a water bath, then dropping hydrogen peroxide, controlling the dropping time, heating and stirring to react after the dropping is completed, then cooling, washing and drying to obtain epoxy composite castor oil; Step (3): adding epoxy composite castor oil and toluene into a container, heating for reaction, then dropping a mixture of toluene diphenyl phosphate, toluene and triphenylphosphine, and after the dropping is completed, heating and stirring for reaction, cooling, adjusting the pH, washing, and drying to obtain a bio-based polyester polyol; The preparation method of the resin additive comprises the following steps: S1: adding gelatin to a container filled with deionized water, mixing evenly, reacting, then adding cellulose to the container, stirring to dissolve, adjusting the pH, then adding a mixture of glyceryl methacrylate, benzoyl peroxide and divinylbenzene, stirring, heating to react, continuing to heat to react, cooling after the reaction is completed, filtering, washing, and drying to obtain resin microspheres; S2: Add sodium aminosulfonate to a container containing deionized water, and then add a swelling agent to obtain a mixture, add resin microspheres under heating conditions, react, and after the reaction is completed, cool, filter, wash, and dry to obtain a resin additive.

2. The method for preparing bio-based polyester polyol according to claim 1, characterized in that: In the step (1), the ratio of castor oil, catalyst and glycerol is (523.6-1047.2) mL: (3.75-7.5) g: (98.64-197.28) mL, the reaction temperature is 180-200°C, the nitrogen introduction time is 30-40 min, the heating reaction temperature is 170-190°C, the time is 3-5 h, the cooling temperature is 35-40°C, and the mixture is washed with distilled water 3-5 times.

3. The method for preparing bio-based polyester polyol according to claim 1, characterized in that: In the step (1), the catalyst is one or more of sodium hydroxide, potassium hydroxide, sodium methoxide and triethanolamine.

4. The method for preparing bio-based polyester polyol according to claim 1, characterized in that: In the step (2), the ratio of the composite castor oil, formic acid, phosphoric acid, resin additive and hydrogen peroxide is (100-120) g: (6.35-7.62) mL: (0.15-0.18) mL: (0.1-0.12) g: (0.25-0.28) mL, the water bath heating temperature is 40-50°C, the dropwise addition time is 30-45 min, the heating and stirring reaction temperature is 60-65°C, the time is 6-8 h, and washing is performed with 1 mol / L sodium hydroxide until the pH value is 7.

5. The method for preparing bio-based polyester polyol according to claim 1, characterized in that: In the S1, the amount ratio of gelatin, deionized water and cellulose is (5-7.5) g: (10-20) mL: (3-5) g, the reaction time is 10-20 min, the stirring and dissolving time is 15-25 min, the pH is adjusted to 7-7.2, the molar ratio of glycerol methacrylate, benzoyl peroxide and divinylbenzene is (2-3): (0.2-0.3): (1-1.4), the stirring rate is 90-100 rpm, the heating reaction temperature is 80-85°C, the time is 2-3h, the heating reaction temperature is continued to be 90-95°C, the time is 2-4h, the filter is filtered with a Buchner funnel, washed with deionized water at 65-80°C, and the drying temperature is 80-90°C for 10-12h.

6. The method for preparing bio-based polyester polyol according to claim 1, characterized in that: In the S2, the dosage ratio of sodium aminosulfonate, deionized water, swelling agent and resin microspheres is (10-18) mL: (50-80) mL: (1-1.5) mL: (15-20) g, the heating temperature is 70-100°C, the pH value during the heating process is 8-10, the reaction time is 15-20h, the product is filtered with a Buchner funnel, washed with deionized water at 65-80°C, and the drying temperature is 80-85°C for 10-12h.

7. The method for preparing bio-based polyester polyol according to claim 1, characterized in that: In S2, the swelling agent is one or more combinations of dimethyl sulfoxide, dichloroethane, dimethylamide and acetone.

8. The method for preparing bio-based polyester polyol according to claim 1, characterized in that: In the step (3), the usage ratio of epoxy composite castor oil, toluene diphenyl phosphate and triphenylphosphine is (100-120) g: (40-48) mL: (0.5-0.6) g, the heating reaction temperature is 40-60°C, the dropwise addition time is 30-45 min, the heating and stirring reaction temperature is 70-75°C, the reaction time is 4-6 h, the pH is adjusted to 7-7.5 with 1 mol / L sodium hydroxide solution, and the mixture is washed with distilled water 3-5 times.

9. A method for applying the bio-based polyester polyol according to any one of claims 1 to 8, characterized in that: Bio-based polyester polyols are used in synthetic polyurethane hot melt adhesives.

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