Preparation of anionic-nonionic sulfonated cardanol-based polyethylene glycol and its application in waterborne polyurethane emulsion

Abstract

The present invention discloses a preparation of anionic nonionic sulfonated cardanol-based polyethylene glycol and its application in aqueous polyurethane emulsion, and belongs to the technical field of polymer materials. The present invention first uses cashew shell extract cardanol as a raw material to prepare a sulfonated cardanol-based polyether polyol with a sulfonic acid anion and a polyethylene glycol nonionic hydrophilic group; the hydroxyl group on the sulfonated cardanol-based polyethylene glycol is reacted with other macromolecular polyols and polyisocyanates, and an anionic nonionic cardanol-based aqueous polyurethane dispersion is prepared by an internal emulsification method. The present invention uses natural cashew shell extract cardanol to replace the petroleum-based products used in the traditional polyurethane industry to synthesize polyether polyols with anionic and nonionic hydrophilic groups for the preparation of aqueous polyurethanes, which is green and environmentally friendly, simple in process, and good in emulsification effect. No small molecule hydrophilic chain extender is required to be added to obtain a stable anionic nonionic aqueous polyurethane emulsion, and has good tensile strength and water resistance, providing a greener solution for the coating industry.

Description

Technical Field

[0001] The invention relates to the preparation of anionic-nonionic sulfonated cardanol-based polyethylene glycol and application of the anionic-nonionic sulfonated cardanol-based polyethylene glycol in aqueous polyurethane emulsion. Background Art

[0002] As a general-purpose polymer material, polyurethane has a wide variety of raw materials and formulas, and is widely used in various industries in daily life, such as coatings, papermaking, and textiles. As people's environmental awareness continues to increase, governments around the world have increased regulation on volatile organic compounds (VOCs) and other hazardous air pollutants (HAPs), and environmentally friendly waterborne polyurethane coatings have developed rapidly. Waterborne polyurethane refers to polyurethane with water as the medium, and the system contains no or very little organic solvent. It not only has the excellent comprehensive properties of solvent-based polyurethane, but also has the advantages of being non-flammable, non-toxic, non-polluting, energy-saving, easy to store, and easy to use. It has become an important direction for the development of the polyurethane field today.

[0003] The main preparation method of waterborne polyurethane is to construct a self-emulsifying anionic waterborne polyurethane by introducing hydrophilic carboxyl or sulfonic acid groups into the molecular chain. Compared with carboxylic acid polyurethane, the preparation process of sulfonate waterborne polyurethane does not require neutralization, has no pungent odor of volatile amines, has a higher ionization strength, and can remain stable in a wider pH range, but in an environment with low pH or high electrolyte content, there is still demulsification and gel precipitation. Therefore, the use of anions alone to synthesize waterborne polyurethane has certain limitations. The combination of anions and non-ions can effectively reduce interfacial tension, improve emulsification efficiency, and give waterborne polyurethane good freeze-thaw resistance and a wider pH range of use.

[0004] In order to meet the global energy and environmental challenges, the development of green and renewable energy has become increasingly urgent. Biomass, as a renewable energy source, is one of the ideal substitutes for petrochemical products. Biomass-derived chemicals converted from biomass are expected to fundamentally solve the environmental damage caused by non-degradable materials in petrochemicals. Polyols prepared from triglyceride oils extracted from rapeseed oil, almond oil, sunflower oil, soybean, linseed and corn are used in polyurethane synthesis. Cardanol is a bio-based phenolic compound extracted from the cashew fruit of the cashew tree. Cardanol has been widely used in the development of plasticizers, stabilizers and laminates as well as for insulation purposes. Due to its low price, the application of cardanol in waterborne polyurethane has attracted attention in recent years. At present, cardanol is mainly used in the preparation of waterborne polyurethane in two forms, namely, cardanol-based diol with dihydroxyl group used as a chain extender (Kattimuttathu I. Suresh, et al., J. Coat. Technol. Res., 2014, 11 (4), pp.619-629), which needs to be added with dimethylol propionic acid as a hydrophilic chain extender to synthesize waterborne polyurethane emulsion; and sulfonated cardanol-based diol used as a small molecule anionic chain extender (Siddhesh U. Mestry, et al., Polymer Bulletin, 2020, 78 (12), pp.6819-6834), which replaces dimethylol propionic acid in the synthesis of waterborne polyurethane. There is no report on anionic-nonionic mixed cardanol-based waterborne polyurethane emulsion. Based on the superior performance and broader application prospects of hybrid waterborne polyurethanes, the development of anionic-nonionic cardanol-based polyols and their application in waterborne polyurethanes is of great significance to reducing the polyurethane industry's dependence on petrochemical resources, reducing the polyurethane industry's carbon emissions and achieving greener and more sustainable development of the polyurethane industry. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing anionic-nonionic bio-based polyols with simple process and green environmental protection in view of the shortcomings of the existing waterborne polyurethane preparation technology, and to apply the method to the preparation of waterborne polyurethane dispersions.

[0006] Specifically, the purpose of the present invention is to provide a method for preparing a self-emulsifying aqueous polyurethane dispersion containing anionic-nonionic sulfonated cardanol-based polyethylene glycol without adding other small molecule hydrophilic chain extenders, thereby providing a greener solution for the preparation of aqueous polyurethane.

[0007] The synthesis route of the anionic-nonionic sulfonated cardanol-based polyethylene glycol described in the present invention is as follows:

[0008]

[0009] The preparation method of the anionic-nonionic cardanol-based polyether polyol of the present invention comprises the following specific steps:

[0010] (1) Dissolve cardanol, epichlorohydrin and a catalyst in an organic solvent, heat to 45-85°C, stir, react for 3-10 hours, add 1 mol / L NaOH ethanol solution, react at 40-60°C for 3-6 hours, and cool to room temperature to obtain a crude product; wash with aqueous solution to pH = 7, remove the water layer, and rotary evaporate the organic phase to remove excess epichlorohydrin to obtain cardanol glycidyl ether.

[0011] (2) Mix the cardanol glycidyl ether obtained in step (1), polyethylene glycol and a catalyst, heat to 100-150° C., and react for 5-10 hours to obtain cardanol-based polyethylene glycol.

[0012] (3) The cardanol-based polyethylene glycol obtained in step (2) is dissolved in an organic solvent, placed in an ice bath at 0-5°C, sodium chlorosulfonate is added dropwise, and the reaction is carried out for 1-3 hours. The temperature is then raised to room temperature and the reaction is carried out for 2-5 hours. Then, a NaOH aqueous solution is added to adjust the pH to 7, the salt is filtered out, and the filtrate is rotary evaporated to remove water and organic solvent to obtain sulfonated cardanol-based polyethylene glycol.

[0013] Wherein, the organic solvent in step (1) is one of ethanol, methanol, benzene and xylene; and the organic solvent in step (3) is methanol or dichloromethane.

[0014] The catalyst is one of tetraethylammonium bromide, triphenylphosphine, benzyltriethylammonium chloride and boron trifluoride etherate, and the amount of the catalyst added is 0.3-0.8wt% of the total mass of the reactants.

[0015] The molar ratio of the cardanol to epichlorohydrin is 1:(3-4), the molar ratio of the cardanol glycidyl ether to polyethylene glycol is 1:(1-2), and the molecular weight of the polyethylene glycol is 600, 800, 1000, or 1500.

[0016] The invention discloses an application of a sulfonated cardanol-based polyethylene glycol containing anionic-nonionic hydrophilic groups in an aqueous polyurethane dispersion, comprising the following steps: mixing the sulfonated cardanol-based polyethylene glycol containing anionic-nonionic hydrophilic groups synthesized by the invention with other macromolecular polyols and polyisocyanates at a molar ratio of 1:(4-8):(6-9), adding an appropriate amount of catalyst, reacting at 70-80°C for 3 hours, cooling to 30-40°C, adding acetone in an amount of 1.5-2.5 times the total mass of isocyanate and polyol to adjust the viscosity, adding a small molecular diamine chain extender, continuing the reaction for 1-2 hours, then adding deionized water in an amount of 2.2-3.3 times the total mass of isocyanate and polyol under high-speed stirring for emulsification and dispersion, and finally removing residual acetone in vacuum to obtain an aqueous polyurethane emulsion.

[0017] The macromolecular polyol is one or more of the following substances with a number average molecular weight of 2000-6000g / mol: poly(1,4-butylene adipate diol), poly(1,6-hexane adipate diol), poly(neopentyl adipate diol), polyethylene adipate diol, polyethylene adipate propylene glycol ester diol, polytetramethylene ether diol; the diisocyanate is one or more of isophorone diisocyanate, hexamethylene diisocyanate, 4,4-dicyclohexylmethane diisocyanate, and toluene diisocyanate; the catalyst is one of dibutyltin dilaurate, stannous octoate, and bismuth neodecanoate; the diol chain extender is one of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, and 1,4-butylene glycol.

[0018] The amount of the catalyst used is 0.2-0.6% of the total mass of the sulfonated cardanol-based polyethylene glycol, other macromolecular polyols and polyisocyanates; the amount of the small molecule diamine chain extender added is 1-2% of the total mass of the sulfonated cardanol-based polyethylene glycol, other macromolecular polyols and polyisocyanates.

[0019] In summary, the advantages of the present invention are: sulfonated cardanol-based polyethylene glycol is synthesized with low-cost bio-based cardanol as the main raw material, replacing the use of polyethylene glycol and sulfonic acid group and carboxyl hydrophilic small molecule chain extenders used in the synthesis of conventional anionic-nonionic waterborne polyurethane. The waterborne polyurethane prepared by the sulfonated cardanol-based polyethylene glycol of the present invention has simple process, is more green and environmentally friendly, is suitable for industrial batch production, and the obtained waterborne polyurethane dispersion has good stability, is less affected by pH value, and has good compatibility, film-forming property and water resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the infrared spectrum of the anionic-nonionic sulfonated cardanol-based polyethylene glycol in Example 1 of the present invention. DETAILED DESCRIPTION

[0021] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with embodiments, but the content of the present invention is not limited to the following embodiments.

[0022] Embodiment 1:

[0023] 30g of cardanol, 10g of epichlorohydrin and 0.4g of benzyltriethylammonium chloride were added to a four-necked bottle equipped with a condensation reflux device, a stirrer, a thermometer and a dropping funnel, and the temperature was raised to 80°C, and the reaction was carried out for 6h. The temperature was then lowered to 50°C, and a 1mol / L NaOH ethanol solution was added (the 1mol / L NaOH ethanol solution in the present invention refers to 1mol NaOH in every 1L of ethanol), and the reaction was carried out at a constant temperature for 6h. The crude product was cooled to room temperature, and washed with aqueous solution until pH = 7, the water layer was removed, and the organic phase was rotary evaporated to remove excess epichlorohydrin to obtain cardanol glycidyl ether.

[0024] The obtained 11g of cardanol glycidyl ether, 18g of polyethylene glycol 600 and 0.15g of triphenylphosphine were mixed, heated to 130°C, and reacted for 6h to obtain cardanol polyethylene glycol. Then 19g of cardanol polyethylene glycol was dissolved in methanol, ice-bathed at 0-5°C, 5g of sodium chlorosulfonate was added dropwise, ice-bathed for 3h, then heated to room temperature for 3h, NaOH aqueous solution was added to adjust to pH=7, the salt was filtered to remove the salt, and the filtrate was rotary evaporated to remove the water and organic solvent to obtain sulfonated cardanol polyethylene glycol 600. The elemental analysis results showed that the S content was 2.2%.

[0025] like Figure 1 Shown are the infrared spectra of cardanol glycerol ether, cardanol-based polyethylene glycol, and sulfonated cardanol-based polyethylene glycol prepared using cardanol as raw material in Example 1.

[0026] 3.3 g of synthesized anionic-nonionic hydrophilic sulfonated cardanol polyethylene glycol 600, 53 g of PBA3000 (poly(1,4-butylene adipate diol)) and 5.59 g of isophorone diisocyanate were mixed, 0.02 g of dibutyltin dilaurate was added, the mixture was reacted at 70-80° C. for 3 hours, the temperature was lowered to 40° C., 150 g of acetone was added to adjust the viscosity, 0.17 g of ethylenediamine was added, the reaction was continued for 1 hour, and then 125 g of deionized water was slowly added under high-speed stirring for emulsification and dispersion, and the residual acetone was finally removed in vacuo to obtain a white waterborne polyurethane emulsion with a solid content of 34.45%.

[0027] Example 2

[0028] This example uses the cardanol glycidyl ether prepared in Example 1.

[0029] 11g of cardanol glycidyl ether, 30g of polyethylene glycol 1000 and 0.21g of triphenylphosphine were mixed, heated to 130°C, and reacted for 6h to obtain cardanol polyethylene glycol 1000. Then 27g of cardanol polyethylene glycol was dissolved in methanol, ice-bathed at 0-5°C, 5g of sodium chlorosulfonate was added dropwise, ice-bathed for 3h, then heated to room temperature for 3h, NaOH aqueous solution was added to adjust to pH=7, salt was filtered to remove, and the filtrate was rotary evaporated to remove water and organic solvent to obtain sulfonated cardanol polyethylene glycol 1000. The elemental analysis results showed that the S content was 1.9%.

[0030] 4.6 g of synthesized anionic-nonionic hydrophilic sulfonated cardanol polyethylene glycol 1000, 51 g of PBA3000 (poly(1,4-butylene adipate diol)), and 5.43 g of isophorone diisocyanate were mixed, 0.03 g of dibutyltin dilaurate was added, and the mixture was reacted at 70° C. for 3 hours. The mixture was cooled to 40° C., 150 g of acetone was added to adjust the viscosity, 0.17 g of ethylenediamine was added, and the reaction was continued for 1 hour. Then, 120 g of deionized water was slowly added under high-speed stirring for emulsification and dispersion. Finally, the residual acetone was removed in vacuo to obtain a white waterborne polyurethane emulsion with a solid content of 34.08%.

[0031] Comparative Example 1

[0032] Polyethylene glycol 600 (PEG) and sodium ethylenediaminesulfonate were used instead of the sulfonated cardanol-based polyethylene glycol 600 in Example 1 to prepare waterborne polyurethane.

[0033] 3g PEG-600, 51g PBA3000 (poly(1,4-butylene adipate diol)) and 5.43g isophorone diisocyanate were mixed, 0.03g dibutyltin dilaurate was added, the mixture was reacted at 70°C for 3 hours, the temperature was lowered to 40°C, 150g acetone was added to adjust the viscosity, 0.53g sodium ethylenediamine sulfonate was added, the reaction was continued for 1 hour, and then 125g deionized water was added under high-speed stirring for emulsification and dispersion, and the residual acetone was finally removed in vacuo to obtain a white water-based polyurethane emulsion with a solid content of 33.67%.

[0034] Comparative Example 2

[0035] Polyethylene glycol 1000 (PEG) and sodium ethylenediamine sulfonate were used instead of the sulfonated cardanol-based polyethylene glycol 1000 in Example 1 to prepare waterborne polyurethane.

[0036] 5g PEG-1000, 51g PBA3000 (poly(1,4-butylene adipate diol)) and 5.43g isophorone diisocyanate were mixed, 0.03g dibutyltin dilaurate was added, the mixture was reacted at 70°C for 3 hours, the temperature was lowered to 40°C, 150g acetone was added to adjust the viscosity, 0.53g sodium ethylenediamine sulfonate was added, the reaction was continued for 1 hour, and then 125g deionized water was added under high-speed stirring for emulsification and dispersion, and the residual acetone was finally removed in vacuo to obtain a white water-based polyurethane emulsion with a solid content of 34.37%.

[0037] Table 1

[0038] Sample name Solid content (%) Water absorption rate (24h) (%) Tensile strength (MPa) Elongation at break (%) Comparative Example 1 33.67 7.88 22.7 530 Comparative Example 2 34.37 13.73 24.7 820 Example 1 34.45 3.48 20.3 480 Example 2 34.08 5.94 22.6 750

[0039] It can be seen from the comparative data in Table 1 above that the anionic-nonionic sulfonated cardanol-based polyethylene glycol prepared by the present invention is used as a polyol in the preparation of waterborne polyurethane, which has a simple process, is green and environmentally friendly, has a good emulsification effect, and does not require the addition of a small molecule hydrophilic chain extender. A stable anionic-nonionic waterborne polyurethane emulsion can be obtained, and has good tensile strength and significantly improved water resistance.

Claims

1. A method for preparing a sulfonated cardanol-based polyethylene glycol containing an anionic-nonionic hydrophilic group, characterized in that: The following steps are involved: Step 1: dissolve cardanol, epichlorohydrin and a catalyst in an organic solvent, heat to 45-85°C, stir, react for 3-10h, add 1mol / L NaOH ethanol solution, react at 40-60°C for 3-6h, cool to room temperature to obtain a crude product; wash with aqueous solution to pH=7, remove the water layer, and rotary evaporate the organic phase to remove excess epichlorohydrin to obtain cardanol glycidyl ether; Step 2: Mix the cardanol glycidyl ether obtained in step 1 with polyethylene glycol and a catalyst, raise the temperature to 100-150° C., and react for 5-10 hours to obtain cardanol-based polyethylene glycol; Step 3: dissolve the cardanol-based polyethylene glycol obtained in step 2 in an organic solvent, place in an ice bath at 0-5°C, drop sodium chlorosulfonate, react for 1-3h, then warm to room temperature and react for 2-5h, then add NaOH aqueous solution to adjust to pH=7, filter to remove salt, and rotary evaporate the filtrate to remove water and organic solvent to obtain sulfonated cardanol-based polyethylene glycol.

2. The method for preparing a sulfonated cardanol-based polyethylene glycol containing an anion-nonionic hydrophilic group as claimed in claim 1, characterized in that: The organic solvent in step 1 is one of ethanol, methanol, benzene and xylene; the organic solvent in step 3 is methanol or dichloromethane.

3. The method for preparing a sulfonated cardanol-based polyethylene glycol containing an anion-nonionic hydrophilic group as claimed in claim 1, characterized in that: The catalysts in step 1 and step 2 are all selected from tetraethylammonium bromide, triphenylphosphine, benzyltriethylammonium chloride and boron trifluoride ether. The catalyst dosage in step 1 is 0.3-0.8wt% of the total mass of the two reactants of cardanol and epichlorohydrin, and the catalyst dosage in step 2 is 0.3-0.8wt% of the total mass of the two reactants of cardanol glycidyl ether and polyethylene glycol.

4. The method for preparing a sulfonated cardanol-based polyethylene glycol containing an anion-nonionic hydrophilic group as claimed in claim 1 or 3, characterized in that: In step 1, the molar ratio of cardanol to epichlorohydrin is 1:(3-4), and in step 2, the molar ratio of cardanol glycidyl ether to polyethylene glycol is 1:(1-2), and the molecular weight of the polyethylene glycol is 600, 1000, 1500 or 2000.

5. Use of a sulfonated cardanol-based polyethylene glycol containing anionic-nonionic hydrophilic groups obtained by the preparation method according to any one of claims 1 to 4 in the preparation of aqueous polyurethane emulsions.

6. The use according to claim 5, characterized in that The anionic-nonionic hydrophilic sulfonated cardanol-based polyethylene glycol prepared by the method described in any one of claims 1 to 4 is mixed with a macromolecular polyol and a diisocyanate in a molar ratio of 1: (4-7): (6-9), an appropriate amount of catalyst is added, the mixture is reacted at 70-80° C. for 3 hours, the temperature is lowered to 30-40° C., acetone is added in an amount of 1.5-2.5 times the total mass of the diisocyanate and the macromolecular polyol to adjust the viscosity, a small molecule diamine chain extender is added, the reaction is continued for 1-2 hours, and then deionized water is added in an amount of 2.2-3.3 times the total mass of the diisocyanate and the macromolecular polyol under high-speed stirring for emulsification and dispersion, and the residual acetone is removed in vacuo to obtain an aqueous polyurethane emulsion.

7. The use according to claim 6, characterized in that The macromolecular polyol is one or more of the following substances with a number average molecular weight of 2000-6000g / mol: poly(1,4-butylene adipate diol), poly(1,6-hexane adipate diol), poly(neopentyl adipate diol), polyethylene adipate diol, polyethylene adipate propylene glycol ester diol or polytetramethylene ether diol; the diisocyanate is one or more of isophorone diisocyanate, hexamethylene diisocyanate, 4,4-dicyclohexylmethane diisocyanate and toluene diisocyanate; the catalyst is one of dibutyltin dilaurate, stannous octoate and bismuth neodecanoate; the diol chain extender is one of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol and 1,4-butylene glycol.

8. The use according to claim 6 or 7, characterized in that The amount of the catalyst used is 0.2-0.6% of the total mass of the sulfonated cardanol-based polyethylene glycol, the macromolecular polyol and the diisocyanate; the amount of the small molecule diamine chain extender added is 1-2% of the total mass of the sulfonated cardanol-based polyethylene glycol, the macromolecular polyol and the diisocyanate.

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