Branched organic urea compound and preparation method and application thereof, block castor oil-based polyester polyol and preparation method thereof, and bio-based polyurethane material

Abstract

The invention belongs to the technical field of polyurethane materials, and particularly relates to a branched organic urea compound and a preparation method and application thereof, block castor oil-based polyester polyol and a preparation method thereof, and a bio-based polyurethane material. The invention provides a branched organic urea compound which has a structure as shown in a formula I. The branched organic urea compound provided by the invention is used as a catalyst for preparing block castor oil-based polyester polyol, has the characteristics of no metal, high efficiency, environmental protection, no need of post-treatment, flame retardance and convenience in industrial production, can be used for preparing reactive flame-retardant castor oil-based polyester polyol which is low in cost and easy to obtain, can improve the performance of bio-based polyurethane, and is suitable for industrial production. Comprising chemical resistance, heat resistance, flexibility, adhesive force and flame retardance.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyurethane materials, and specifically relates to a branched organic urea compound and a preparation method and application thereof, a segmented castor oil-based polyester polyol and a preparation method thereof, and a bio-based polyurethane material. Background Art

[0002] Castor oil is a natural triglyceride with hydroxyl groups and long fatty acid chains in its molecular structure. As a type of non-edible vegetable oil, it has the advantages of high relative density, high flash point, low freezing point, green environmental protection, renewable nature, good biodegradability, and low ecotoxicity. It can be used to replace petrochemical-based polyester polyols in the preparation of various functional polyurethane materials.

[0003] However, castor oil is subject to certain limitations in practical applications due to its low hydroxyl value, poor reactivity, easy shrinkage, and poor flame retardancy. By preparing it into derivatives through ester exchange reactions, its hydroxyl value, mechanical properties, and crosslinking density of polyurethane materials can be improved.

[0004] Catalyst selection is the key to synthesizing castor oil-based polyester polyols by the ester exchange method. Currently, common catalysts include organometallic compound catalysts such as alkali metal and alkaline earth metal alcohol salt catalysts, organic titanium catalysts, organic tin catalysts, and organic samarium catalysts. These catalysts have high catalytic activity, but have the disadvantages of difficulty in catalyst separation, affecting polyurethane performance, and heavy metal pollution that endangers human health. When using catalysts such as small molecule organic amines, they have the advantages of higher activity and lower reaction temperature, but have the disadvantages of difficulty in post-processing separation, affecting the performance of polyurethane materials (including chemical resistance, heat resistance, flexibility and adhesion), and easy catalyst migration. Summary of the Invention

[0005] The present invention aims to provide a branched organic urea compound, a preparation method and application thereof, a segmented castor oil-based polyester polyol and a preparation method thereof, and a bio-based polyurethane material. The branched organic urea compound provided by the present invention is used as a catalyst for preparing the segmented castor oil-based polyester polyol, and has the advantages of being metal-free, having high catalytic activity, and requiring no post-treatment. At the same time, the branched organic urea compound can play a flame retardant role and has good compatibility, and can significantly improve the performance of the bio-based polyurethane material, including chemical resistance, heat resistance, flexibility, adhesion, and flame retardancy.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a branched organic urea compound having a structure shown in Formula I:

[0008]

[0009] The present invention provides a method for preparing the branched organic urea compound described in the above technical solution, comprising the following steps:

[0010] In a protective gas atmosphere, 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, an organic solvent and m-toluene isocyanate are mixed and reacted to obtain the branched organic urea compound.

[0011] The present invention provides the use of the branched organic urea compound described in the above technical solution or the branched organic urea compound prepared by the preparation method described in the above technical solution as a catalyst in the preparation of castor oil-based polyester polyol.

[0012] The present invention provides a method for preparing a segmented castor oil-based polyester polyol, comprising the following steps:

[0013] Mixing castor oil, a catalyst and a block product to carry out an ester exchange reaction to obtain the blocked castor oil-based polyester polyol;

[0014] The catalyst is a branched organic urea compound having a structure shown in Formula I:

[0015]

[0016] The block comprises one or more of nitrogen-containing linear polyols, nitrogen-containing branched polyols and nitrogen-containing heterocyclic polyols.

[0017] Preferably, the castor oil has an acid value of ≤2.0 mgKOH / g and a hydroxyl value of 154-170 mgKOH / g;

[0018] The block material includes one or more of cashew nut shell oil Mannich polyol, 1,3,5-tris(2-hydroxyethyl)cyanuric acid, tetrahydroxyethylethylenediamine, hydroxyethylhexahydro-s-triazine and N,N,N,N-tetrakis(2-hydroxypropyl)-p-phenylenediamine;

[0019] The cashew nut shell liquid Mannich polyol has a hydroxyl value of 240 to 480 mg KOH / g, the hydroxyl value of the 1,3,5-tris(2-hydroxyethyl)cyanuric acid has a hydroxyl value of 630 to 650 mg KOH / g, the hydroxyl value of the tetrahydroxyethylethylenediamine has a hydroxyl value of 940 to 955 mg KOH / g, the hydroxyl value of the hydroxyethylhexahydro-s-triazine has a hydroxyl value of 760 to 770 mg KOH / g, and the hydroxyl value of the N,N,N,N-tetrakis(2-hydroxypropyl)-p-phenylenediamine has a hydroxyl value of 650 to 665 mg KOH / g;

[0020] The mass ratio of the castor oil to the block is 45-75:15-40.

[0021] Preferably, the mass ratio of the castor oil to the catalyst is 45-75:0.01-0.08.

[0022] Preferably, the transesterification reaction comprises sequentially performing a first-stage transesterification reaction and a second-stage transesterification reaction; the temperature of the first-stage transesterification reaction is 60 to 170° C., the time is 8 to 15 hours, and the first-stage transesterification reaction is carried out in a protective gas atmosphere; the temperature of the second-stage transesterification reaction is 60 to 170° C., the time is 1 to 8 hours, and the second-stage transesterification reaction is carried out under vacuum conditions, with a vacuum degree of -0.1 to -0.085 MPa;

[0023] After the transesterification reaction is completed, an ester exchange reaction liquid is obtained. After obtaining the transesterification reaction liquid, the method further comprises: removing the vacuum from the transesterification reaction liquid, heating it, and then removing impurities under vacuum conditions. After cooling, the blocked castor oil-based polyester polyol is obtained. The impurity removal temperature is 130 to 220° C., the time is 2 to 6 hours, and the vacuum degree is -0.1 to -0.09 MPa.

[0024] The present invention provides a segmented castor oil-based polyester polyol prepared by the preparation method described in the above technical solution.

[0025] Preferably, the hydroxyl value of the segmented castor oil-based polyester polyol is 180-400 mg KOH / g, and the acid value is ≤1.5 mg KOH / g.

[0026] The present invention provides a bio-based polyurethane material, wherein the polyester polyol chain segments constituting the bio-based polyurethane material include the segmented castor oil-based polyester polyol described in the above technical solution.

[0027] The present invention provides a branched organic urea compound having a structure represented by Formula I. The branched organic urea compound having a structure represented by Formula I provided by the present invention is used as a catalyst for preparing castor oil-based polyester polyols. The compound is metal-free, highly efficient, environmentally friendly, requires no post-treatment, and is flame-retardant. It can be used to prepare inexpensive and readily available reactive flame-retardant castor oil-based polyester polyols, thereby enhancing the competitiveness of the bio-based polyurethane industry.

[0028] The present invention provides a method for preparing a segmented castor oil-based polyester polyol, comprising the steps of: mixing castor oil, a catalyst, and a segmented material to undergo an ester exchange reaction to obtain the segmented castor oil-based polyester polyol. The present invention employs a branched organic urea compound having a structure represented by Formula I as a catalyst, which has the advantages of high catalytic activity, being metal-free, flame retardant, and not affecting the performance of polyurethanes. The catalyst used in the present invention contains a branched, cyclic stereostructure and exhibits a suitable steric hindrance effect, enabling it to catalyze a directional, single ester exchange reaction between the segmented material and castor oil. Specifically, the catalyst effectively catalyzes the ester exchange reaction between the segmented material and castor oil, while minimally catalyzing the reaction between the segmented material and diglyceride, a product of the ester exchange reaction, thereby obtaining a mixture of diglyceride and the segmented castor oil-based polyester polyol. This significantly reduces the formation of small molecules such as glycerol and monoglyceride, thereby improving the performance (including chemical resistance, heat resistance, flexibility, and adhesion) of polyurethanes prepared from the segmented castor oil-based polyester polyol.

[0029] At the same time, the present invention uses nitrogen- or nitrogen-heterocyclic block products and castor oil as raw materials, and introduces castor oil fatty acid chain segments into the molecular structure of the block products through a selective ester exchange reaction, thereby preparing a bio-based branched, multi-functional, low-molecular-weight, and highly reactive segmented castor oil-based polyester polyol containing both nitrogen- or nitrogen-heterocyclic polyester chain segments and long side chain segments of castor oil fatty acids. The segmented castor oil-based polyester polyol can react chemically with isocyanate (NCO) groups to prepare a bio-based polyurethane material. Moreover, the introduction of the nitrogen- or nitrogen-heterocyclic polyester chain segments improves the chemical resistance, flame retardancy, flexibility, and adhesion of the segmented castor oil-based polyester polyol.

[0030] The preparation method of the segmented castor oil-based polyester polyol provided by the present invention is simple, the raw materials are widely available and easily obtained, and the polyol is safer and more environmentally friendly to humans and nature, and has broad application prospects. DETAILED DESCRIPTION

[0031] The present invention provides a branched organic urea compound having a structure shown in Formula I:

[0032]

[0033] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0034] The present invention provides a method for preparing the branched organic urea compound described in the above technical solution, comprising the following steps:

[0035] In a protective gas atmosphere, 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, an organic solvent and meta-toluene isocyanate are mixed and reacted to obtain the branched organic urea compound. In the present invention, the protective gas preferably includes nitrogen and / or a rare gas, and the rare gas may be argon. In the embodiment, the protective gas may be nitrogen. The organic solvent is preferably tetrahydrofuran, and in the embodiment, it may be anhydrous tetrahydrofuran. The molar ratio of the 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and the meta-toluene isocyanate is preferably 100:360. The present invention has no special requirements for the amount of the organic solvent used, as long as the reaction is ensured to proceed smoothly. In the present invention, the mixing preferably includes: dissolving the 2,4,6-tris(4-aminophenyl)-1,3,5-triazine in a portion of the organic solvent to obtain a 2,4,6-tris(4-aminophenyl)-1,3,5-triazine solution; dissolving the m-toluene isocyanate in the remaining organic solvent to obtain a m-toluene isocyanate solution; and dropwise adding the m-toluene isocyanate solution to the 2,4,6-tris(4-aminophenyl)-1,3,5-triazine solution. The reaction preferably includes sequentially conducting a first-stage reaction and a second-stage reaction. The first-stage reaction temperature can be room temperature (20-30°C) and the reaction time is preferably 15-20 hours. The second-stage reaction is preferably conducted under reflux conditions and the reaction time is preferably 8-10 hours. In the present invention, after the reaction is completed, a reaction solution is obtained. After obtaining the reaction solution, the present invention preferably further includes: desolvating the reaction solution, washing, and drying the reaction solution to obtain the branched organic urea compound. The desolvation is preferably conducted under vacuum conditions. The reagent used for the washing is preferably diethyl ether. The drying method is preferably oven drying.

[0036] The present invention provides the use of the branched organic urea compound described in the above technical solution or the branched organic urea compound prepared by the preparation method described in the above technical solution as a catalyst in the preparation of castor oil-based polyester polyol.

[0037] The present invention provides a method for preparing a segmented castor oil-based polyester polyol, comprising the following steps:

[0038] Mixing castor oil, a catalyst and a block product to carry out an ester exchange reaction to obtain the blocked castor oil-based polyester polyol;

[0039] The catalyst is a branched organic urea compound having a structure shown in Formula I:

[0040]

[0041] The block comprises one or more of nitrogen-containing linear polyols, nitrogen-containing branched polyols and nitrogen-containing heterocyclic polyols.

[0042] In the present invention, the acid value of the castor oil is preferably ≤2.0 mgKOH / g, more preferably ≤1.5 mgKOH / g. The hydroxyl value of the castor oil is preferably 154-170 mgKOH / g, more preferably 156-167 mgKOH / g.

[0043] In the present invention, the block preferably includes one or more of cashew nut shell liquid Mannich polyol, 1,3,5-tris(2-hydroxyethyl)cyanuric acid, tetrahydroxyethylethylenediamine, hydroxyethylhexahydro-s-triazine and N,N,N,N-tetrakis(2-hydroxypropyl)-p-phenylenediamine.

[0044] In the present invention, the cashew nut shell liquid Mannich polyol is a cashew nut shell liquid bio-based polyol synthesized by using cashew nut shell liquid, formaldehyde and diethanolamine to undergo Mannich reaction.

[0045] In the present invention, the preparation method of N,N,N,N-tetrakis(2-hydroxypropyl)-p-phenylenediamine preferably comprises: adding 1085 g (10 mol) of p-phenylenediamine and 1000 mL of toluene to an autoclave equipped with a thermometer, mechanical stirring, cooling and heating facilities, stirring and heating the mixture to 30-55° C. under N2 protection, gradually pressurizing 2382 g (41 mol) of propylene oxide into the reactor, completing the addition within 4 hours, continuing the reaction for 6 hours, and after the pressure in the reactor drops, heating the mixture to 100° C. and continuing the reaction for 4 hours, then starting a vacuum pump to remove low-boiling-point substances under negative pressure to obtain 3237.7 g of N,N,N,N-tetrakis(2-hydroxypropyl)-p-phenylenediamine with a yield of 95.1%.

[0046] In the present invention, the hydroxyl value of the cashew nut shell liquid Mannich polyol is preferably 240 to 480 mg KOH / g, and in the embodiment, it can be 430 mg KOH / g. The hydroxyl value of the 1,3,5-tris(2-hydroxyethyl)cyanuric acid is preferably 630 to 650 mg KOH / g, and in the embodiment, it can be 644 mg KOH / g. The hydroxyl value of the tetrahydroxyethylethylenediamine is preferably 940 to 955 mg KOH / g. The hydroxyl value of the hydroxyethylhexahydro-s-triazine is preferably 760 to 770 mg KOH / g. The hydroxyl value of the N,N,N,N-tetrakis(2-hydroxypropyl)-p-phenylenediamine is preferably 650 to 665 mg KOH / g, and in the embodiment, it can be 659 mg KOH / g. The present invention uses the above-mentioned high-hydroxyl-value, multifunctional, and thermally stable block compound as a raw material to prepare a segmented castor oil-based polyester polyol. The resulting bio-based polyurethane material based on this segmented castor oil-based polyester polyol exhibits excellent chemical resistance, heat resistance, flexibility, and adhesion. The mass ratio of castor oil to block compound is preferably 45-75:15-40, more preferably 50-70:18-35, and even more preferably (2.4-5:1). In embodiments, it can be 30:12.5, 30:8.5, 30:6, 30:12, or 30:11. The mass ratio of the castor oil to the catalyst is preferably 45-75:0.01-0.08, more preferably 50-70:0.02-0.05, further preferably (1000-3500):1, and most preferably (1200-3000):1. In embodiments, the ratio may be 30:0.01, 30:0.015, 30:0.02, or 30:0.025. In the present invention, the mixing is preferably performed in a protective gas atmosphere, and the protective gas preferably includes nitrogen and / or a rare gas. The rare gas may be argon. In embodiments, the protective gas may be nitrogen.

[0047] In the present invention, the transesterification reaction preferably includes a first-stage transesterification reaction and a second-stage transesterification reaction carried out sequentially. The temperature of the first-stage transesterification reaction is preferably 60-170°C, more preferably 70-160°C, even more preferably 80-150°C, and in an embodiment, it can be 110°C. The time of the first-stage transesterification reaction is preferably 8-15 hours, more preferably 9-13 hours, even more preferably 10-12 hours, and in an embodiment, it can be 11 hours. The heating rate to the temperature of the first-stage transesterification reaction is preferably 15-25°C / h, more preferably 25°C / h, and in an embodiment, it can be 20°C / h. The first-stage transesterification reaction is preferably carried out in a protective gas atmosphere, and the protective gas preferably includes nitrogen and / or a rare gas. The rare gas can be argon, and in an embodiment, the protective gas can be nitrogen.

[0048] In the present invention, the temperature of the second-stage transesterification reaction is preferably 60 to 170°C, more preferably 70 to 160°C. The duration of the second-stage transesterification reaction is preferably 1 to 8 hours, more preferably 3 to 7 hours, even more preferably 3 to 6 hours, and in embodiments, may be 4 hours. The second-stage transesterification reaction is preferably carried out under vacuum conditions, with a vacuum degree of preferably -0.1 to -0.085 MPa, more preferably -0.1 to -0.09 MPa.

[0049] In the present invention, after the transesterification reaction is completed, a transesterification reaction liquid is obtained. After obtaining the transesterification reaction liquid, the present invention preferably further comprises: removing the vacuum from the transesterification reaction liquid, heating it, then removing impurities under vacuum, and cooling it to obtain the segmented castor oil-based polyester polyol. In the present invention, the gas used for removing the vacuum is preferably nitrogen and / or a noble gas. The noble gas may be argon. In embodiments, the gas used for removing the vacuum may be nitrogen. The heating rate is preferably 20-30°C / h, more preferably 25°C / h. The temperature for removing impurities is preferably 130-220°C, more preferably 150-210°C. The time for removing impurities is preferably 2-6 hours, more preferably 3-5 hours, and in embodiments, it may be 4 hours. The vacuum degree for removing impurities is preferably -0.1 to -0.09 MPa, more preferably -0.1 to -0.095 MPa.

[0050] The product obtained by the ester exchange reaction of the present invention contains blocked castor oil-based polyester polyol, diglyceride and catalyst. The blocked castor oil-based polyester polyol, diglyceride and catalyst in the product obtained by the ester exchange reaction of the present invention do not need to be separated. The blocked castor oil-based polyester polyol, diglyceride and catalyst are used as the blocked castor oil-based polyester polyol product prepared by the present invention for the preparation of bio-based polyurethane materials.

[0051] The present invention provides a segmented castor oil-based polyester polyol prepared by the preparation method described in the above technical solution.

[0052] The segmented castor oil-based polyester polyol product provided by the present invention is preferably a mixture comprising segmented castor oil-based polyester polyol, diglyceride and a catalyst.

[0053] In the present invention, the hydroxyl value of the block castor oil-based polyester polyol is preferably 180-400 mg KOH / g, and in the embodiment, it can be 242 mg KOH / g. The acid value of the block castor oil-based polyester polyol is preferably ≤1.5 mg KOH / g, and in the embodiment, it can be 0.5 mg KOH / g.

[0054] In the present invention, the viscosity of the segmented castor oil-based polyester polyol at 25° C. is preferably 600 mPa·s to 4000 mPa·s, and in embodiments may be 980 mPa·s, 1380 mPa·s, 860 mPa·s, or 1080 mPa·s.

[0055] In the present invention, the average relative molecular mass of the segmented castor oil-based polyester polyol is 500 g / mol to 850 g / mol, and in embodiments may be 662 g / mol, 596 g / mol, 655 g / mol or 635 g / mol.

[0056] The present invention provides a bio-based polyurethane material, wherein the polyester polyol chain segments constituting the bio-based polyurethane material include the segmented castor oil-based polyester polyol described in the above technical solution.

[0057] The raw materials for preparing the bio-based polyurethane material provided by the present invention preferably include polyester polyol and isocyanate, wherein the polyester polyol preferably includes the segmented castor oil-based polyester polyol described in the above technical solution. The isocyanate is preferably diphenylmethane diisocyanate.

[0058] In the present invention, the isocyanate index (R value) of the bio-based polyurethane material is preferably 1.1.

[0059] The present invention provides a method for preparing the bio-based polyurethane material described in the above technical solution, preferably comprising the following steps: mixing the segmented castor oil-based polyester polyol and isocyanate, degassing, and then curing to obtain the bio-based polyurethane material. The curing preferably comprises a first-stage curing and a second-stage curing, wherein the first-stage curing temperature is preferably room temperature and the curing time is preferably 5 to 7 hours. The second-stage curing temperature is preferably 45 to 55°C and the curing time is preferably 12 to 16 hours.

[0060] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0061] The preparation method of the branched organic urea catalyst having the structure shown in Formula I used in the following examples is specifically as follows:

[0062] Under nitrogen protection, 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (35.4 g, 100 mmol) and anhydrous tetrahydrofuran (100 mL) were added to a 500 mL three-necked flask and mixed evenly. A mixed solution of m-toluene isocyanate (47.9 g, 360 mmol) and 150 mL of anhydrous tetrahydrofuran was slowly added dropwise under vigorous stirring. After reacting at room temperature for 20 h, the temperature was slowly raised and refluxed for 10 h. The tetrahydrofuran was spin-dried under vacuum conditions, and then 300 mL of ether was added. The mixture was stirred for 2 h, washed, filtered, and dried to obtain a branched organic urea catalyst as a white solid (71 g).

[0063] Example 1:

[0064] 30 kg of castor oil was added to a dry, nitrogen-filled stainless steel reactor. 0.010 kg of a branched organic urea catalyst and 12.5 kg of a cashew nut shell liquid Mannich polyol block having a hydroxyl value of 430 mg KOH / g were added to the reactor. The reactor was heated to 110° C. at a rate of 20° C. / h and the reaction was maintained for 11 h. The reactor was then evacuated and the reaction was continued at a vacuum of -0.09 MPa for 4 h.

[0065] After the vacuum was broken by nitrogen, the reactor was heated to 210°C at a rate of 25°C / h, and impurities were removed at -0.1 MPa high vacuum for 4 h. The temperature was then lowered to obtain segmented castor oil-based polyester polyol.

[0066] The segmented castor oil-based polyester polyol prepared in this example has a hydroxyl value of 242 mg KOH / g, an acid value of 0.5 mg KOH / g, a viscosity (25° C.) of 980 mPa·s, and an average relative molecular mass of 662 g / mol.

[0067] Example 2:

[0068] 30 kg of castor oil was added to a dry, nitrogen-filled stainless steel reactor. 0.015 kg of a branched organic urea catalyst and 8.5 kg of a 1,3,5-tris(2-hydroxyethyl)cyanuric acid block having a hydroxyl value of 644 mg KOH / g were added to the reactor. The reactor was heated to 110° C. at a rate of 20° C. / h and maintained for 11 h. The reactor was then evacuated and the reaction was continued at a vacuum of -0.09 MPa for 4 h.

[0069] After the vacuum was broken by nitrogen, the reactor was heated to 210°C at a rate of 25°C / h, and impurities were removed at -0.1 MPa high vacuum for 4 h. The temperature was then lowered to obtain segmented castor oil-based polyester polyol.

[0070] The segmented castor oil-based polyester polyol prepared in this example has a hydroxyl value of 270 mg KOH / g, an acid value of 0.4 mg KOH / g, a viscosity (25° C.) of 1380 mPa·s, and an average relative molecular mass of 596 g / mol.

[0071] Example 3:

[0072] 30 kg of castor oil was added to a dry, nitrogen-filled stainless steel reactor. 0.015 kg of a branched organic urea catalyst, 6 kg of a cashew nut shell liquid Mannich polyol having a hydroxyl value of 430 mg KOH / g, and 4.5 kg of a 1,3,5-tris(2-hydroxyethyl)cyanuric acid block having a hydroxyl value of 644 mg KOH / g were added to the reactor. The reactor was heated to 110° C. at a rate of 20° C. / h and maintained for 11 h. The reactor was then evacuated and the reaction was continued at a vacuum of -0.09 MPa for 4 h.

[0073] After the vacuum was broken by nitrogen, the reactor was heated to 210°C at a rate of 25°C / h, and impurities were removed at -0.1 MPa high vacuum for 4 h. The temperature was then lowered to obtain segmented castor oil-based polyester polyol.

[0074] The segmented castor oil-based polyester polyol prepared in this example has a hydroxyl value of 256 mg KOH / g, an acid value of 0.5 mg KOH / g, a viscosity (25° C.) of 1160 mPa·s, and an average relative molecular mass of 627 g / mol.

[0075] Example 4:

[0076] 30 kg of castor oil was added to a dry, nitrogen-filled stainless steel reactor. 0.025 kg of a branched organic urea catalyst and 11 kg of N,N,N,N-tetrakis(2-hydroxypropyl)-p-phenylenediamine block having a hydroxyl value of 659 mg KOH / g were added to the reactor. The reactor was heated to 110° C. at a rate of 20° C. / h and maintained for 11 h. The reactor was then evacuated and the reaction was continued at a vacuum of -0.09 MPa for 4 h.

[0077] After the vacuum was broken by nitrogen, the reactor was heated to 210°C at a rate of 25°C / h, and impurities were removed at -0.1 MPa high vacuum for 4 h. The temperature was then lowered to obtain segmented castor oil-based polyester polyol.

[0078] The segmented castor oil-based polyester polyol prepared in this example has a hydroxyl value of 296 mg KOH / g, an acid value of 0.5 mg KOH / g, a viscosity (25° C.) of 1080 mPa·s, and an average relative molecular mass of 635 g / mol.

[0079] Comparative Example 1 (using a branched organic urea catalyst and reducing the amount of nitrogen-containing block added):

[0080] 30 kg of castor oil was added to a dry, nitrogen-filled stainless steel reactor. 0.015 kg of branched organic urea catalyst, 3.2 kg of cashew nut shell liquid Mannich polyol with a hydroxyl value of 430 mg KOH / g, and 2.1 kg of 1,3,5-tris(2-hydroxyethyl)cyanuric acid block with a hydroxyl value of 644 mg KOH / g were added to the reactor. The reactor was heated to 110° C. at a rate of 20° C. / h and maintained for 11 h. The reactor was then evacuated and the reaction was continued at a vacuum of -0.09 MPa for 4 h.

[0081] After the vacuum was broken by nitrogen, the reactor was heated to 210°C at a rate of 25°C / h, and impurities were removed at -0.1 MPa high vacuum for 4 h. The temperature was then lowered to obtain segmented castor oil-based polyester polyol.

[0082] The segmented castor oil-based polyester polyol prepared in this comparative example has a hydroxyl value of 215 mg KOH / g, an acid value of 0.4 mg KOH / g, a viscosity (25° C.) of 930 mPa·s, and an average relative molecular mass of 730 g / mol.

[0083] Comparative Example 2 (using traditional catalyst and reducing the amount of nitrogen-containing block added):

[0084] 30 kg of castor oil was added to a dry, nitrogen-filled stainless steel reactor. 0.015 kg of dibutyltin dilaurate catalyst, 3.2 kg of cashew nut shell liquid Mannich polyol with a hydroxyl value of 430 mg KOH / g, and 2.1 kg of 1,3,5-tris(2-hydroxyethyl)cyanuric acid block with a hydroxyl value of 644 mg KOH / g were added to the reactor. The reactor was heated to 110° C. at a rate of 20° C. / h and maintained for 11 h. The reactor was then evacuated and the reaction was continued at a vacuum of -0.09 MPa for 4 h.

[0085] After the vacuum was broken by nitrogen, the reactor was heated to 210°C at a rate of 25°C / h, and impurities were removed at -0.1 MPa high vacuum for 4 h. The temperature was then lowered to obtain segmented castor oil-based polyester polyol.

[0086] The segmented castor oil-based polyester polyol prepared in this comparative example has a hydroxyl value of 213 mg KOH / g, an acid value of 0.5 mg KOH / g, a viscosity (25° C.) of 940 mPa·s, and an average relative molecular mass of 726 g / mol.

[0087] Application examples:

[0088] Performance testing was conducted on the segmented castor oil-based polyester polyols prepared in Examples 1-4 and Comparative Examples 1-2. The testing method was as follows: nitrogen was introduced into a reaction flask, and the segmented castor oil-based polyester polyols prepared in Examples 1-4 and Comparative Examples 1-2 were mixed with diphenylmethane diisocyanate curing agent at an R value of 1.1. After stirring uniformly, vacuum was applied to remove bubbles, and an adhesion test was performed. The polyols were then poured into the corresponding molds for curing at room temperature for 5-7 hours. The reaction was then continued in a drying oven at 45-55°C for 12-16 hours. The resulting bio-based polyurethane materials were cooled and demolded to obtain the corresponding materials. Sample specifications complied with GB / T 1040.1-2018 and GB / T 2406.2-2009. The oxygen index of the samples was measured using an oxygen index meter, and the tensile strength of the bio-based polyurethane materials was measured using a WAW-C universal testing machine. The test results are shown in Table 1.

[0089] Table 1 Performance test results of Examples 1 to 5 and Comparative Examples 1 to 2

[0090]

[0091] As shown in Table 1, the bio-based polyurethane materials made from the castor oil-based polyester polyols prepared in Examples 1 to 4 have excellent chemical resistance, heat resistance, flexibility and adhesion, and have high flame retardancy. Comparison of the oxygen index data of Comparative Example 1 and Comparative Example 2 shows that the branched organic urea catalyst has certain flame retardancy.

[0092] As can be seen from the above examples, the branched organic urea catalyst employed in the present invention has advantages such as low reaction temperature, high catalytic activity, low addition dosage, metal-free, flame retardant, and no impact on polyurethane performance. It contains a branched, cyclic stereostructure with a suitable steric hindrance effect, capable of catalyzing a directional, single transesterification reaction between the block product and castor oil, thereby obtaining a diglyceride and castor oil-based block polyester polyol molecular structure. This significantly reduces the formation of small molecules such as glycerol and monoglyceride, and improves the performance of polyurethanes prepared from the castor oil-based block polyester polyol.

[0093] The present invention adds a nitrogen- or nitrogen-heterocyclic block compound and a branched organic urea catalyst to castor oil for a selective transesterification reaction, followed by high vacuum and heating for impurity removal and dehydration. Castor oil fatty acid chains are introduced into the molecular structure of the block compound to synthesize a bio-based, branched, multifunctional, low-molecular-weight, highly active polyester polyol containing both nitrogen- or nitrogen-heterocyclic polyester chains and long castor oil fatty acid side chain segments.

[0094] The block materials used in the present invention, namely, cashew nut shell oil Mannich polyol, 1,3,5-tris(2-hydroxyethyl)cyanuric acid, hydroxyethyl hexahydro-s-triazine, tetrahydroxyethylethylenediamine, and N,N,N,N-tetrakis(2-hydroxypropyl)-p-phenylenediamine, are all small molecule raw materials containing nitrogen or nitrogen heterocycles, have high hydroxyl values, multifunctionality, and good thermal stability. The prepared castor oil-based block polyester polyol has excellent chemical resistance, heat resistance, flexibility, and adhesion.

[0095] The preparation method of the castor oil-based block polyester polyol of the present invention is simple, the raw materials are widely available and easily obtained, and the polyol is safer and more environmentally friendly to humans and nature, and has broad application prospects.

[0096] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A branched organic urea compound, characterized in that Having the structure shown in formula I:

2. The method for preparing the branched organic urea compound according to claim 1, wherein The following steps are involved: In a protective gas atmosphere, 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, an organic solvent and m-toluene isocyanate are mixed and reacted to obtain the branched organic urea compound.

3. Use of the branched organic urea compound according to claim 1 or the branched organic urea compound prepared by the preparation method according to claim 2 as a catalyst in the preparation of castor oil-based polyester polyol.

4. A method for preparing a segmented castor oil-based polyester polyol, characterized in that: The following steps are involved: Mixing castor oil, a catalyst and a block product to carry out an ester exchange reaction to obtain the blocked castor oil-based polyester polyol; The catalyst is a branched organic urea compound having a structure shown in Formula I: The block comprises one or more of nitrogen-containing linear polyols, nitrogen-containing branched polyols and nitrogen-containing heterocyclic polyols.

5. The preparation method according to claim 4, characterized in that The castor oil has an acid value of ≤2.0 mgKOH / g and a hydroxyl value of 154 to 170 mgKOH / g; The block material includes one or more of cashew nut shell oil Mannich polyol, 1,3,5-tris(2-hydroxyethyl)cyanuric acid, tetrahydroxyethylethylenediamine, hydroxyethylhexahydro-s-triazine and N,N,N,N-tetrakis(2-hydroxypropyl)-p-phenylenediamine; The cashew nut shell liquid Mannich polyol has a hydroxyl value of 240 to 480 mg KOH / g, the hydroxyl value of the 1,3,5-tris(2-hydroxyethyl)cyanuric acid has a hydroxyl value of 630 to 650 mg KOH / g, the hydroxyl value of the tetrahydroxyethylethylenediamine has a hydroxyl value of 940 to 955 mg KOH / g, the hydroxyl value of the hydroxyethylhexahydro-s-triazine has a hydroxyl value of 760 to 770 mg KOH / g, and the hydroxyl value of the N,N,N,N-tetrakis(2-hydroxypropyl)-p-phenylenediamine has a hydroxyl value of 650 to 665 mg KOH / g; The mass ratio of the castor oil to the block is 45-75:15-40.

6. The preparation method according to claim 4, characterized in that The mass ratio of the castor oil to the catalyst is 45-75:0.01-0.

08.

7. The preparation method according to any one of claims 4 to 6, characterized in that: The transesterification reaction comprises a first-stage transesterification reaction and a second-stage transesterification reaction, wherein the temperature of the first-stage transesterification reaction is 60 to 170° C., the time is 8 to 15 hours, and the first-stage transesterification reaction is carried out in a protective gas atmosphere; the temperature of the second-stage transesterification reaction is 60 to 170° C., the time is 1 to 8 hours, and the second-stage transesterification reaction is carried out under vacuum conditions, with a vacuum degree of -0.1 to -0.085 MPa; After the transesterification reaction is completed, an ester exchange reaction liquid is obtained. After obtaining the transesterification reaction liquid, the method further comprises: removing the vacuum from the transesterification reaction liquid, heating it, and then removing impurities under vacuum conditions. After cooling, the blocked castor oil-based polyester polyol is obtained. The impurity removal temperature is 130 to 220° C., the time is 2 to 6 hours, and the vacuum degree is -0.1 to -0.09 MPa.

8. The segmented castor oil-based polyester polyol prepared by the preparation method according to any one of claims 4 to 7.

9. The segmented castor oil-based polyester polyol according to claim 8, characterized in that The hydroxyl value of the segmented castor oil-based polyester polyol is 180-400 mg KOH / g, and the acid value is ≤1.5 mg KOH / g.

10. A bio-based polyurethane material, characterized in that: The polyester polyol chain segments constituting the bio-based polyurethane material include the segmented castor oil-based polyester polyol according to claim 8 or 9.

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