A phosphorus-containing organic thiourea catalyst, a preparation method and application thereof and a bio-based block polyester polyol, a preparation method and application thereof

Abstract

The present application belongs to the technical field of bio-based polyols, and particularly relates to a phosphorus-containing organic thiourea catalyst, a preparation method and application thereof, and a bio-based block polyester polyol and a preparation method and application thereof. The phosphorus-containing organic thiourea catalyst provided by the present application has the characteristics of metal-free, high catalytic activity, flame retardation, and no need for removal and separation. The present application uses castor oil, an aromatic ring-containing polyol, and the phosphorus-containing organic thiourea catalyst in the above scheme, introduces the fatty acid chain segment of castor oil into the molecular structure of the aromatic ring-containing polyol through selective ester exchange reaction, and obtains a bio-based block polyester polyol containing saturated polyether chain segments and fatty acid chain segments of castor oil as side groups. The bio-based block polyester polyol provided by the present application contains two and three aromatic ring chain segments, and provides good acid and alkali resistance, heat resistance, and wear resistance for coatings, has excellent chemical properties, especially excellent chemical resistance, good mechanical properties and physical properties, and reliable comprehensive performance.

Description

Technical Field

[0001] This invention belongs to the field of bio-based polyol technology, specifically relating to a phosphorus-containing organic thiourea catalyst, its preparation method and application, and bio-based block polyester polyols, their preparation methods and applications. Background Technology

[0002] Concrete floors are susceptible to erosion due to carbonation and high loads, leading to structural damage and surface cracking. Floor coatings are an effective way to reduce or delay structural damage and surface cracking of concrete floors. Polyurethane floor coatings, as a high-performance, multi-functional floor coating, have advantages such as good elasticity, flexibility, crack resistance, weather resistance, slip resistance, wear resistance, and good decorative properties, which can significantly improve the service life of concrete floors.

[0003] To reduce the consumption of non-renewable resources, researchers have developed bio-based raw materials for polyurethane floor coatings, such as castor oil, palm oil, soybean oil, or cashew nut shell oil, to replace or partially replace petroleum-based raw materials—polyester polyols. These materials have advantages such as wide availability, renewability, and low environmental pollution. However, the resulting polyurethane has the problem of poor acid and alkali resistance. Summary of the Invention

[0004] The purpose of this invention is to provide a phosphorus-containing organothiourea catalyst, its preparation method and application, and a bio-based block polyester polyol, its preparation method and application. The polyurethane prepared from the bio-based block polyester polyol provided by this invention has good acid and alkali resistance and excellent chemical properties.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a phosphorus-containing organothiourea catalyst with the structure shown in Formula I:

[0007]

[0008] The present invention also provides a method for preparing the phosphorus-containing organothiourea catalyst described above, comprising the following steps:

[0009] The phosphorus-containing organothiourea catalyst was obtained by sequentially carrying out nucleophilic addition reactions of 3,5-bis(trifluoromethyl)phenyl isothiocyanate, 2-(diphenylphosphino)ethylamine and a good solvent, followed by oxidation of trivalent phosphorus under oxygen conditions.

[0010] Preferably, the molar ratio of 3,5-bis(trifluoromethyl)phenyl isothiocyanate and 2-(diphenylphosphino)ethylamine is 1:1 to 1.05.

[0011] The present invention also provides the application of the phosphorus-containing organothiourea catalyst described in the above-described scheme or the phosphorus-containing organothiourea catalyst obtained by the preparation method described in the above-described scheme in transesterification reactions.

[0012] The present invention also provides a bio-based block polyester polyol, the structure of which is shown in Formula II:

[0013]

[0014] In Equation II, Ar is

[0015] The average relative molecular mass of the bio-based block polyester polyol is 600–800 g / mol.

[0016] Preferably, the bio-based block polyester polyol has a hydroxyl value of 160-400 mg KOH / g, an acid value of ≤2 mg KOH / g, and a viscosity (25°C) of 1000-3500 mPa.s.

[0017] This invention also provides a method for preparing the bio-based block polyester polyol described above, comprising the following steps:

[0018] A phosphorus-containing organothiourea catalyst, an aromatic ring-containing polyol, and dried castor oil are mixed and subjected to an ester exchange reaction to obtain the bio-based block polyester polyol; the phosphorus-containing organothiourea catalyst is the phosphorus-containing organothiourea catalyst described in the above scheme or the phosphorus-containing organothiourea catalyst obtained by the preparation method described in the above scheme.

[0019] Preferably, the transesterification reaction is carried out in a protective atmosphere; the transesterification reaction includes a normal pressure transesterification stage and a vacuum transesterification stage in sequence; the temperature of the normal pressure transesterification stage is 80-180℃, and the holding time is 5-10h; the temperature of the vacuum transesterification stage is 80-180℃, the vacuum degree is -100 to -80kPa, and the holding time is 2-5h.

[0020] The present invention also provides the application of the bio-based block polyester polyol described in the above-described scheme or the bio-based block polyester polyol obtained by the preparation method described in the above-described scheme in coatings.

[0021] The present invention also provides a polyurethane, wherein the polyester polyol raw material is the bio-based block polyester polyol described in the above scheme or the bio-based block polyester polyol obtained by the preparation method described in the above scheme.

[0022] This invention provides a phosphorus-containing organothiourea catalyst. The phosphorus-containing organothiourea catalyst provided by this invention contains two strongly electron-withdrawing trifluoromethyl groups and multiple benzene ring structures, exhibiting strong reactivity and significant steric hindrance. It can catalyze a directed, single transesterification reaction between polyols and castor oil triesters, yielding castor oil diester and castor oil block polyester polyol molecules. This significantly reduces the formation of small molecule products such as glycerol and castor oil monoester, thereby improving the performance and interpenetrating network structure of polyurethanes prepared from bio-based block polyester polyols. Furthermore, the phosphorus-containing organothiourea catalyst provided by this invention is metal-free and possesses high catalytic activity. It also exhibits flame-retardant properties, greatly improving the safety of the products prepared by its catalysis. The high catalytic activity of this phosphorus-containing organothiourea catalyst requires a small dosage, has no impact on subsequent polyurethane material preparation, and eliminates the need for separation.

[0023] This invention also provides a method for preparing the phosphorus-containing organothiourea catalyst described above. The preparation method provided by this invention is simple in steps, convenient to operate, safe, highly feasible, and suitable for industrial production.

[0024] This invention also provides the application of the phosphorus-containing organothiourea catalyst described in the above-described scheme or the phosphorus-containing organothiourea catalyst prepared by the above-described scheme in transesterification reactions. The phosphorus-containing organothiourea catalyst provided by this invention can be used to prepare polyurethane raw materials, especially bio-based block polyester polyols. The resulting bio-based block polyester polyols have good activity, are easy to react to form polyurethane, have low molecular weight, excellent comprehensive performance, and high added value.

[0025] This invention also provides a bio-based block polyester polyol. The bio-based block polyester polyol provided by this invention contains difunctional and trifunctional aromatic ring segments, providing excellent acid and alkali resistance, heat resistance, and abrasion resistance for floor coatings. It exhibits excellent chemical properties, especially chemical resistance, as well as good mechanical and physical properties, resulting in reliable overall performance. The bio-based block polyester polyol provided by this invention contains castor oil fatty acid side chains, endowing the floor coating with excellent flexibility, weather resistance, water resistance, moisture resistance, and adhesion, enabling it to adapt well to changes in environmental temperature, possessing good UV resistance, greatly extending its service life, and facilitating application. This invention, through chemical composition and molecular structure modification, yields a bio-based block polyester polyol with high activity and low molecular weight.

[0026] This invention also provides a method for preparing the bio-based block polyester polyol described in the above-mentioned scheme. This invention uses castor oil, an aromatic ring-containing polyol, and the phosphorus-containing organothiourea catalyst described in the above-mentioned scheme. Through selective transesterification, fatty acid segments of castor oil are introduced into the molecular structure of the aromatic ring-containing polyol, yielding a bio-based block polyester polyol containing saturated polyether segments and castor oil fatty acid segments as side groups. The preparation method provided by this invention is simple, uses widely available raw materials, is safer for humans, more environmentally friendly, and has broad application prospects.

[0027] This invention also provides the application of the bio-based block polyester polyol described in the above-described scheme or the bio-based block polyester polyol obtained by the preparation method described in the above-described scheme in coatings. The bio-based block polyester polyol provided by this invention has a small molecular weight, is characterized by multiple hydroxyl groups and high branching, and can be used to prepare polyurethane floor coatings. It enables the cured floor coating to form a complete interpenetrating network structure of soft and hard segments, giving the floor coating film good chemical, physical, and mechanical properties, good resistance to chemical corrosion, good heat stability, and good adhesion. It is suitable for preparing polyurethane floor coatings with various properties, especially two-component solvent-free polyurethane floor coatings.

[0028] This invention also provides a polyurethane, wherein the polyester polyol raw material is the bio-based block polyester polyol described in the above-described scheme or the bio-based block polyester polyol obtained by the preparation method described in the above-described scheme. The polyurethane provided by this invention, when used in floor coatings, enables the cured floor coating to form a complete interpenetrating network structure of soft and hard segments, resisting chemical corrosion and not being swollen, dissolved, damaged, decomposed, or corroded by chemical media. It remains stable over a long period, exhibiting good hardness, impact resistance, weather resistance, abrasion resistance, and heat stability. Furthermore, it possesses good adhesion, low air permeability, and low water permeability, effectively meeting the various performance requirements of floor coatings. Detailed Implementation

[0029] This invention provides a phosphorus-containing organothiourea catalyst with the structure shown in Formula I:

[0030]

[0031] The phosphorus-containing organothiourea catalyst provided by this invention has the characteristics of being metal-free, having high catalytic activity, being flame-retardant, and not requiring removal and separation.

[0032] The present invention also provides a method for preparing the phosphorus-containing organothiourea catalyst described above, comprising the following steps:

[0033] The phosphorus-containing organothiourea catalyst was obtained by sequentially carrying out nucleophilic addition reactions of 3,5-bis(trifluoromethyl)phenyl isothiocyanate, 2-(diphenylphosphino)ethylamine and a good solvent, followed by oxidation of trivalent phosphorus under oxygen conditions.

[0034] This invention involves mixing 3,5-bis(trifluoromethyl)phenyl isothiocyanate, 2-(diphenylphosphino)ethylamine, and a good solvent (denoted as the first mixture) to obtain a reaction solution. In this invention, the molar ratio of 3,5-bis(trifluoromethyl)phenyl isothiocyanate and 2-(diphenylphosphino)ethylamine can be from 1:1 to 1.05, specifically 1:1, 1:1.01, 1:1.02, 1:1.03, 1:1.04, or 1:1.05.

[0035] In this invention, the good solvent can be a substituted hydrocarbon; the substituted hydrocarbon can be a substituted alkane; the substituted alkane can be a haloalkane; the haloalkane can be a chloroalkane; the chloroalkane can be a C1-C8 chloroalkane; and the C1-C8 chloroalkane can be dichloromethane.

[0036] In this invention, the molar ratio of 2-(diphenylphosphino)ethylamine to the volume ratio of the good solvent can be 2 mol:(3-5) L, specifically 2 mol:4 L.

[0037] In this invention, the first mixing can be carried out in a protective atmosphere; the protective atmosphere can be an inert gas; the inert gas can be argon. By mixing in a protective atmosphere, this invention can avoid the influence of oxygen on catalyst activity and esterification reaction, as well as the generation of byproducts.

[0038] In this invention, the first mixing can be as follows: mixing 2-(diphenylphosphino)ethylamine with a first portion of a good solvent to obtain a 2-(diphenylphosphino)ethylamine solution; mixing 3,5-bis(trifluoromethyl)phenyl isothiocyanate with the remaining portion of the good solvent to obtain a premix; and then adding the 2-(diphenylphosphino)ethylamine solution dropwise to the premix under stirring conditions. This invention, through the above mixing sequence and method, can avoid the generation of byproducts and improve the conversion rate of the target product.

[0039] In this invention, the volume ratio of the first portion of good solvent to the remaining portion of good solvent can be 1:2 to 3, specifically 1:2.5.

[0040] In this invention, the stirring rate of the stirring conditions can be 200 to 500 rpm, specifically 300 rpm or 400 rpm.

[0041] In this invention, the dripping rate can be 10-20 mL / min, specifically 15 mL / min.

[0042] After obtaining the reaction solution, the present invention performs a nucleophilic addition reaction on the reaction solution to obtain a trivalent phosphorus organothiourea compound. In the present invention, the nucleophilic addition reaction can be carried out under a protective atmosphere; the protective atmosphere can be an inert gas; the inert gas can be argon; the temperature of the nucleophilic addition reaction can be 20-40°C, specifically 25°C or 35°C, and the holding time can be 20-48 hours, specifically 24 hours or 36 hours.

[0043] After obtaining the trivalent phosphorus organothiourea compound, the present invention performs an oxidation reaction of the trivalent phosphorus in oxygen conditions to obtain the phosphorus-containing organothiourea catalyst. In the present invention, the oxygen conditions can be: introducing oxygen into the reaction solution of the nucleophilic addition reaction; the oxygen introduction rate can be 0.1–0.5 L / min, specifically 0.1 L / min, 0.3 L / min, or 0.5 L / min. By slowly introducing oxygen, the present invention avoids the volatilization of the organic solvent and the precipitation of the target product.

[0044] In this invention, the oxidation temperature of the trivalent phosphorus can be 20-30°C, specifically 25°C, and the holding time can be 2-10 min, specifically 5 min.

[0045] In this invention, the oxidation reaction of trivalent phosphorus may further include removing the solvent from the resulting reaction system; the solvent removal may be carried out by evaporation; the evaporation may be carried out by vacuum evaporation; the evaporation temperature may be 20-40°C, specifically 30°C, and the holding time may be 1-2 hours, specifically 1.5 hours; the vacuum degree of the vacuum evaporation may be -0.095 to -0.100 MPa, specifically -0.097 MPa.

[0046] In this invention, the solvent removal process may further include mixing the resulting solid with n-hexane (referred to as the second mixture) followed by solid-liquid separation and drying. By mixing with n-hexane, this invention can further improve the purity of the phosphorus-containing organothiourea catalyst.

[0047] In this invention, the volume ratio of the solid to n-hexane can be (5-10) g:(20-40) mL, specifically 5 g:20 mL, 5 g:30 mL, 5 g:40 mL, 8 g:20 mL, 8 g:30 mL, 8 g:40 mL, 10 g:20 mL, 10 g:30 mL or 10 g:40 mL.

[0048] In this invention, the second mixing can be stirring mixing, the stirring speed can be 50 to 100 rpm, specifically 60 rpm, and the mixing time can be 1 to 3 hours, specifically 2 hours.

[0049] In this invention, the solid-liquid separation can be filtration; the drying can be vacuum drying; the vacuum degree of the vacuum drying can be -0.095 to -0.100 MPa; the temperature of the vacuum drying can be 30 to 50°C, specifically 40°C, and the heat preservation time can be 6 to 12 hours, specifically 8 hours or 10 hours.

[0050] The present invention also provides the application of the phosphorus-containing organothiourea catalyst described in the above-described scheme or the phosphorus-containing organothiourea catalyst obtained by the preparation method described in the above-described scheme in transesterification reactions.

[0051] The phosphorus-containing organothiourea catalyst provided by this invention can be used in transesterification reactions to prepare polyurethane raw material polyester polyols or polyurethanes, especially bio-based block polyester polyols. The resulting bio-based block polyester polyols have high functional groups, good activity, low molecular weight, excellent comprehensive performance, and high added value.

[0052] The present invention also provides a bio-based block polyester polyol, the structure of which is shown in Formula II:

[0053]

[0054] In Equation II, Ar is

[0055]

[0056] The average relative molecular mass of the bio-based block polyester polyol is 600–800 g / mol.

[0057] In this invention, the hydroxyl value of the bio-based block polyester polyol can be 160-400 mg KOH / g, the acid value can be ≤2 mg KOH / g, and the viscosity (25°C) can be 1000-3500 mPa.s.

[0058] This invention also provides a method for preparing the bio-based block polyester polyol described above, comprising the following steps:

[0059] A phosphorus-containing organothiourea catalyst, an aromatic ring-containing polyol, and dried castor oil are mixed (referred to as the third mixture) and subjected to transesterification to obtain the bio-based block polyester polyol; the phosphorus-containing organothiourea catalyst is the phosphorus-containing organothiourea catalyst described in the above scheme or the phosphorus-containing organothiourea catalyst obtained by the preparation method described in the above scheme.

[0060] In this invention, the aromatic ring polyol may have one or more aromatic rings, specifically one, two, or three; the aromatic ring polyol may be a branched aromatic ring polyol; the branched aromatic ring polyol may be a saturated polyether polyol; the saturated polyether polyol may include one or more of polyether polyols, polyoxyethylene ether polyols, and polyoxypropylene ether polyols.

[0061] In this invention, the polyether polyol can be cashew nut shell oil polyether polyol; the hydroxyl value of the cashew nut shell oil polyether polyol can be 320-380 mg KOH / g, specifically 340 mg KOH / g or 360 mg KOH / g.

[0062] In this invention, the polyoxyethylene ether polyol can be bisphenol A polyoxyethylene ether polyol; the hydroxyl value of the bisphenol A polyoxyethylene ether polyol can be 180-350 mg KOH / g, specifically 210 mg KOH / g, 240 mg KOH / g, 270 mg KOH / g, 300 mg KOH / g or 330 mg KOH / g.

[0063] In this invention, the polyoxypropylene ether polyol may include one or more of bisphenol A polyoxypropylene ether polyol, hydroquinone-based polyoxypropylene ether polyol, and 2,5-di-tert-butylhydroquinone-based polyoxypropylene ether polyol.

[0064] In this invention, the hydroxyl value of the bisphenol A polyoxypropylene ether polyol can be 160-335 mg KOH / g, specifically 220 mg KOH / g, 270 mg KOH / g, or 320 mg KOH / g.

[0065] In this invention, the hydroxyl value of the hydroquinone-based polyoxypropylene ether polyol can be 190-495 mg KOH / g, specifically 240 mg KOH / g, 280 mg KOH / g, 320 mg KOH / g, 360 mg KOH / g, 400 mg KOH / g, 430 mg KOH / g, or 480 mg KOH / g.

[0066] In this invention, the hydroxyl value of the 2,5-di-tert-butylhydroquinone polypropylene ether polyol can be 165-330 mg KOH / g, specifically 200 mg KOH / g, 240 mg KOH / g, 280 mg KOH / g, or 310 mg KOH / g.

[0067] In this invention, the mass ratio of the phosphorus-containing organothiourea catalyst to the aromatic ring-containing polyol can be 6-8:7000-13000, specifically 6:7000, 7:9000, 8:9000, or 8:13000. The phosphorus-containing organothiourea catalyst provided by this invention has high catalytic activity, therefore requiring only a small amount to reduce cost and post-processing difficulty.

[0068] In this invention, the water content of the dried castor oil may not exceed 2000 ppm, specifically it may be 500 ppm, 1000 ppm or 1500 ppm.

[0069] In this invention, the method for preparing the dried castor oil may include the following steps: heating the castor oil under a protective atmosphere and vacuum conditions. This invention, through the above method, removes impurities from the castor oil while simultaneously dehydrating it. By using dehydration, this invention avoids affecting catalyst activity and the transesterification reaction.

[0070] In this invention, the acid value of the castor oil can be ≤2.0mgKOH / g, specifically 1.5mgKOH / g, and the hydroxyl value can be 154~168mgKOH / g, specifically 158mgKOH / g or 166mgKOH / g.

[0071] In this invention, the protective atmosphere can be an inert gas or nitrogen; the inert gas can be argon.

[0072] In this invention, the vacuum degree of the vacuum condition can be -100 to -85 kPa, specifically -90 kPa or -95 kPa.

[0073] In this invention, the heating process may include a heating and then heat preservation period; the heating rate may be 20°C / h; and the heat preservation time may be 1h.

[0074] In this invention, the heating temperature can be 80-130°C, specifically 90°C, 100°C, 110°C or 120°C, and the heat preservation time can be 1-5 hours, specifically 2 hours, 3 hours or 4 hours.

[0075] In this invention, the mass ratio of the dried castor oil to the aromatic ring polyol can be 45-75:20-40, specifically 50:22, 55:22, 60:22, 65:22, 70:22, 50:26, 55:26, 60:26, 65:26, 70:26, 50:30, 55:30, 60:30, 65:30, 70:30, 50:35, 55:35, 60:35, 65:35, 70:35, 50:38, 55:38, 60:38, 65:38, or 70:38.

[0076] In this invention, the third mixing device can be a dry stainless steel reactor.

[0077] In this invention, the third mixing can be: premixing dried castor oil and a phosphorus-containing organothiourea catalyst to obtain a premix, and then mixing the premix with an aromatic ring polyol.

[0078] In this invention, the transesterification reaction may be preceded by heating to the temperature of the transesterification reaction; the heating rate may be 15-25°C / h, specifically 20°C / h.

[0079] In this invention, the transesterification reaction can be carried out in a protective atmosphere; the protective atmosphere can be an inert gas or nitrogen; the inert gas can be argon; the transesterification reaction can include a normal pressure transesterification stage and a vacuum transesterification stage in sequence.

[0080] In this invention, the temperature of the atmospheric pressure transesterification stage can be 80–180°C, specifically 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, or 175°C, and the holding time can be 5–10 hours, specifically 6 hours, 7 hours, 8 hours, or 9 hours. By using the phosphorus-containing organothiourea catalyst provided by this invention, this invention achieves the preparation of bio-based block polyester polyols at low reaction temperatures.

[0081] In this invention, the temperature of the vacuum ester exchange stage can be 80 to 180°C, specifically 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, or 175°C; the vacuum degree can be -100 to -80 kPa, specifically -95 kPa, -90 kPa, or -85 kPa; and the heat preservation time can be 2 to 5 hours, specifically 3 hours or 4 hours.

[0082] In this invention, the reaction system may be cooled after the transesterification reaction; the cooling rate may be 20-40°C / h, specifically 30°C / h, and the final temperature may be 40-60°C, specifically 50°C.

[0083] The present invention also provides the application of the bio-based block polyester polyol described in the above-described scheme or the bio-based block polyester polyol obtained by the preparation method described in the above-described scheme in coatings.

[0084] The bio-based block polyester polyol provided by this invention has high functionality and small molecular weight, and can be used to prepare polyurethane floor coatings. It enables the cured floor coating to form a complete interpenetrating network structure of soft and hard segments, giving the floor coating film good chemical, physical and mechanical properties, good resistance to chemical corrosion, good heat stability, and good adhesion. It is suitable for preparing polyurethane floor coatings with various properties, especially two-component solvent-free polyurethane floor coatings.

[0085] The present invention also provides a polyurethane, wherein the polyester polyol raw material is the bio-based block polyester polyol described in the above scheme or the bio-based block polyester polyol obtained by the preparation method described in the above scheme.

[0086] The polyurethane provided by this invention is used in floor coatings, which enables the cured floor coating to form a complete interpenetrating network structure of soft and hard segments. It is resistant to chemical corrosion and is not swollen, dissolved, damaged, decomposed, or corroded by chemical media. It remains stable for a long time and has good hardness, impact resistance, weather resistance, wear resistance, and heat stability. In addition, it has good adhesion, low air permeability, and water permeability, which can well meet the various performance requirements of floor coatings.

[0087] To further illustrate the present invention, the following detailed description of the embodiments is provided in conjunction with the present invention, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0088] Example 1

[0089] Under argon protection, 3,5-bis(trifluoromethyl)phenyl isothiocyanate (27.1 g, 100 mmol) and dichloromethane (100 mL) were mixed thoroughly. A dichloromethane solution (2 mmol / mL) of 2-(diphenylphosphino)ethylamine (22.9 g, 100 mmol) was added dropwise (at a rate of 15 mL / min) with vigorous stirring (300 rpm). The reaction was carried out at 25 °C for 24 h. Oxygen was then slowly introduced into the reaction solution at 0.3 L / min, and the reaction continued for 5 min. The dichloromethane was evaporated to dryness under vacuum (-0.1 MPa) at 30 °C. Then, n-hexane (200 mL) was added, and the mixture was stirred vigorously (60 rpm) for 2 h. After filtration, the mixture was dried at 40 °C under a vacuum of -0.1 MPa for 8 h to obtain 49 g of a phosphorus-containing organothiourea catalyst, which was a white solid.

[0090] 25 kg of castor oil (acid value 1.8 mg KOH / g, hydroxyl value 161.0 mg KOH / g) was added to a dry stainless steel reactor filled with nitrogen. The reactor was heated to 120 °C at a rate of 20 °C / h and held at that temperature for 1 h. The reactor was then subjected to impurity removal and dehydration at 120 °C and a vacuum of -95 kPa for 3 h.

[0091] 8.0g of phosphorus-containing organothiourea catalyst and 13kg of cashew nut shell oil polyether polyol with a hydroxyl value of 340mg KOH / g were added to the reactor. The reactor was heated to 130℃ at a rate of 20℃ / h and held at that temperature for 6h. Then, the reactor was evacuated for transesterification reaction and the reaction was continued for 3h under a vacuum of -90kPa. The temperature was then lowered to 50℃ at a rate of 30℃ / h to obtain bio-based block polyester polyol.

[0092] The bio-based block polyester polyol prepared in this embodiment has a hydroxyl value of 224 mg KOH / g, an acid value of 0.6 mg KOH / g, a viscosity (25℃) of 1480 mPa.s, and an average relative molecular mass of 723 g / mol.

[0093] Example 2

[0094] 25 kg of castor oil (acid value 1.8 mg KOH / g, hydroxyl value 161.0 mg KOH / g) was added to a dry stainless steel reactor filled with nitrogen. The reactor was heated to 120 °C at a rate of 20 °C / h and held at that temperature for 1 h. The reactor was then subjected to impurity removal and dehydration under a vacuum of -95 kPa for 3 h.

[0095] 7.0 g of phosphorus-containing organothiourea catalyst (Example 1) and 9.0 kg of bisphenol A polyoxypropylene ether polyol with a hydroxyl value of 322 mg KOH / g were added to the reactor. The reactor was heated to 130 °C at a rate of 20 °C / h and held at that temperature for 6 h. Then, the reactor was evacuated to carry out the transesterification reaction. The reaction was continued for 3 h under a vacuum of -90 kPa. The temperature was then lowered to 60 °C at a rate of 20 °C / h to obtain a bio-based block polyester polyol.

[0096] The bio-based block polyester polyol prepared in this embodiment has a hydroxyl value of 206 mg KOH / g, an acid value of 0.7 mg KOH / g, a viscosity (25℃) of 1720 mPa.s, and an average relative molecular mass of 652 g / mol.

[0097] Example 3

[0098] 25 kg of castor oil (acid value 1.8 mg KOH / g, hydroxyl value 161.0 mg KOH / g) was added to a dry stainless steel reactor filled with nitrogen. The reactor was heated to 120 °C at a rate of 20 °C / h and held at that temperature for 1 h. The reactor was then subjected to impurity removal and dehydration under a vacuum of -95 kPa for 3 h.

[0099] 6.2g of phosphorus-containing organothiourea catalyst (Example 1), 7.0kg of cashew nut shell oil polyether polyol with a hydroxyl value of 340mgKOH / g, and 4.5kg of bisphenol A polyoxypropylene ether polyol with a hydroxyl value of 322mgKOH / g were added to the reactor. The reactor was heated to 130℃ at a rate of 20℃ / h and held at that temperature for 6h. Then, the reactor was evacuated to carry out the transesterification reaction. The reaction was continued for 3h under a vacuum of -90kPa. The temperature was then lowered to 40℃ at a rate of 40℃ / h to obtain bio-based block polyester polyol.

[0100] The bio-based block polyester polyol prepared in this embodiment has a hydroxyl value of 217 mg KOH / g, an acid value of 0.5 mg KOH / g, a viscosity (25℃) of 1590 mPa.s, and an average relative molecular mass of 689 g / mol.

[0101] Example 4

[0102] 25 kg of castor oil (acid value 1.8 mg KOH / g, hydroxyl value 161.0 mg KOH / g) was added to a dry stainless steel reactor filled with nitrogen. The reactor was heated to 120 °C at a rate of 20 °C / h and held at that temperature for 1 h. The reactor was then subjected to impurity removal and dehydration under a vacuum of -95 kPa for 3 h.

[0103] 8.0 g of phosphorus-containing organothiourea catalyst (Example 1) and 9.0 kg of 2,5-di-tert-butylhydroquinone polypropylene ether polyol with a hydroxyl value of 325 mg KOH / g were added to the reactor. The reactor was heated to 130 °C at a rate of 20 °C / h and held at that temperature for 6 h. Then, the reactor was evacuated to carry out the transesterification reaction. The reaction was continued for 3 h under a vacuum of -90 kPa. The temperature was then lowered to 50 °C at a rate of 30 °C / h to obtain bio-based block polyester polyol.

[0104] The bio-based block polyester polyol prepared in this embodiment has a hydroxyl value of 208 mg KOH / g, an acid value of 0.6 mg KOH / g, a viscosity (25℃) of 1950 mPa.s, and an average relative molecular mass of 644 g / mol.

[0105] Comparative Example 1 (using a conventional catalyst)

[0106] 25 kg of castor oil (acid value 1.8 mg KOH / g, hydroxyl value 161.0 mg KOH / g) was added to a dry stainless steel reactor filled with nitrogen. The reactor was heated to 120 °C at a rate of 20 °C / h and held at that temperature for 1 h. The reactor was then subjected to impurity removal and dehydration under a vacuum of -95 kPa for 3 h.

[0107] 8.0 g of dibutyltin dilaurate and 13 kg of cashew nut shell oil polyether polyol with a hydroxyl value of 340 mg KOH / g were added to the reactor. The reactor was heated to 130 °C at a rate of 20 °C / h and held at that temperature for 6 h. Then, the reactor was evacuated for transesterification and the reaction was continued for 3 h under a vacuum of -90 kPa. The temperature was then lowered to 50 °C at a rate of 30 °C / h to obtain bio-based block polyester polyol.

[0108] The bio-based block polyester polyol prepared in this comparative example has a hydroxyl value of 221 mg KOH / g, an acid value of 0.5 mg KOH / g, a viscosity (25℃) of 1535 mPa.s, and an average relative molecular mass of 733 g / mol.

[0109] Comparative Example 2 (using a conventional catalyst)

[0110] 25 kg of castor oil (acid value 1.8 mg KOH / g, hydroxyl value 161.0 mg KOH / g) was added to a dry stainless steel reactor filled with nitrogen. The reactor was heated to 120 °C at a rate of 20 °C / h and held at that temperature for 1 h. The reactor was then subjected to impurity removal and dehydration under a vacuum of -95 kPa for 3 h.

[0111] 8.0 g of tetrabutyl titanate and 13 kg of cashew nut shell oil polyether polyol with a hydroxyl value of 340 mg KOH / g were added to the reactor. The reactor was heated to 130 °C at a rate of 20 °C / h and held at that temperature for 6 h. Then, the reactor was evacuated to carry out the transesterification reaction. The reaction was continued for 3 h under a vacuum of -90 kPa. The temperature was then lowered to 50 °C at a rate of 30 °C / h to obtain bio-based block polyester polyol.

[0112] The bio-based block 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℃) of 1360 mPa.s, and an average relative molecular mass of 678 g / mol.

[0113] Test Example 1

[0114] The performance of the bio-based block polyester polyols prepared in Examples 1-4 and Comparative Examples 1-2 was tested. The test method was as follows: the bio-based block polyester polyols prepared in Examples 1-4 and Comparative Examples 1-2 were mixed with HT-300 curing agent at an R value of 1.05 to prepare two-component solvent-free floor coatings. The two-component solvent-free floor coatings were then uniformly coated on the floor surface with a thickness of 0.5 mm. The performance of the floor surface coating was tested according to the requirements of the national standard GB / T22374-2018. The test results are shown in Table 1.

[0115] Table 1 Performance test results of Examples 1-4 and Comparative Examples 1-2

[0116]

[0117] As shown in Table 1, the bio-based block polyester polyols prepared in Examples 1-4 were prepared by introducing specific aromatic rings into the molecular structure of natural castor oil through a series of impurity removal, dehydration and transesterification reactions, thereby producing block polyester polyols with excellent mechanical properties, temperature resistance and water resistance, which greatly improved the chemical corrosion resistance and wear resistance of two-component solvent-free floor coatings.

[0118] As can be seen from the above embodiments, the bio-based block polyester polyol provided by the present invention can be used to prepare polyurethane floor coatings, enabling the floor coating to form a complete soft and hard segment interpenetrating network structure, giving the floor coating film good chemical, physical and mechanical properties, resistance to chemical corrosion, and not being swollen, dissolved, destroyed, decomposed and corroded by chemical media. It remains stable for a long time and can well meet the various performance index requirements of floor coatings, and meet the special requirements of industrial flooring, commercial flooring and public facilities.

[0119] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for the preparation of a bio-based block polyester polyol, characterized in that, The method comprises the following steps: a nucleophilic addition reaction, an oxidation reaction of trivalent phosphorus in an oxygen condition, and removal of a solvent from a reaction system after the oxidation reaction of trivalent phosphorus, wherein the 3,5-bis(trifluoromethyl)phenyl isothiocyanate, the 2-(diphenylphosphino)ethylamine, and a good solvent are mixed in sequence; an ester exchange reaction is performed by mixing the phosphorus-containing organic thiourea catalyst, an aromatic ring-containing polyol, and dried castor oil to obtain the bio-based block polyester polyol; the molar ratio of the 3,5-bis(trifluoromethyl)phenyl isothiocyanate to the 2-(diphenylphosphino)ethylamine is 1:1-1.05; the mass ratio of the phosphorus-containing organic thiourea catalyst to the aromatic ring-containing polyol is 6-8:7000-3000; the mass ratio of the dried castor oil to the aromatic ring-containing polyol is 45-75:20-40; the aromatic ring-containing polyol is one or more of cashew nut shell oil polyether polyol, bisphenol A polyoxyethylene ether polyol, bisphenol A polyoxypropylene ether polyol, p-phenylenediamine-based polyoxypropylene ether polyol, and 2,5-di-tert-butyl-p-phenylenediamine-based polyoxypropylene ether polyol; the ester exchange reaction is performed in a protective atmosphere; the ester exchange reaction comprises performing an atmospheric ester exchange stage and a vacuum ester exchange stage in sequence; the temperature of the atmospheric ester exchange stage is 80-180°C, and the holding time is 5-10 h; the temperature of the vacuum ester exchange stage is 80-180°C, the vacuum degree is -100--80 kPa, and the holding time is 2-5 h.

2. The production method according to claim 1, characterized by, The bio-based block polyester polyol has a hydroxyl value of 160-400 mg KOH / g, an acid value of ≤2 mg KOH / g, and a viscosity of 1000-3500 mPa.s at 25°C.

3. Use of the bio-based block polyester polyol obtained by the preparation method of any one of claims 1-2 in a coating.

4. A polyurethane characterized by, The polyester polyol raw material is the bio-based block polyester polyol obtained by the preparation method of any one of claims 1-2.

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