A bio-based polyurethane coating and its preparation method

Abstract

This invention discloses a bio-based polyurethane coating and its preparation method, belonging to the field of coating technology. The bio-based polyurethane coating comprises the following raw materials in parts by weight: 100 parts plant oil polyol, 70-120 parts isocyanate, 10-25 parts flame retardant, 30-40 parts organic solvent, 1-5 parts catalyst, 10-30 parts hydrophilic chain extender, 10-30 parts neutralizing agent, and 20-40 parts deionized water. The plant polyol, isocyanate, flame retardant, organic solvent, and catalyst are added to a container and mixed to obtain a prepolymer mixture. Then, the hydrophilic chain extender is added, and the mixture is further mixed to obtain a polymer mixture. After cooling, a neutralizing agent is added for neutralization, and then deionized water is added to emulsify and form a polyurethane emulsion. The bio-based polyurethane coating is obtained after vacuum distillation. This invention uses a biomass-derived acid to react with an organosilicon compound to generate a flame retardant, and the prepared bio-based polyurethane coating possesses excellent flame-retardant properties.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a bio-based polyurethane coating and its preparation method. Background Technology

[0002] Polyurethane is a polymer with repeating urethane segments, produced by the reaction of isocyanates and polyols. Polyurethane products are broadly classified into foamed and non-foamed products. Foamed products include flexible, rigid, and semi-rigid polyurethane foams; non-foamed products include coatings, adhesives, synthetic leather, elastomers, and elastic fibers. Polyurethane materials have excellent properties, wide applications, and numerous product types, with polyurethane coatings being the most widely used.

[0003] In recent years, with increased environmental awareness and focus on personal health, coupled with stringent environmental regulations regarding the emission of volatile organic compounds (VOCs) and the content of harmful solvents, the application of polyurethane coatings containing solvents and organic fillers has been severely restricted. This has spurred the development of polyurethane coatings towards water-based, powder-based, and high-solids formulations. Among these, water-based polyurethane coatings, using water as the dispersion medium, have received significant attention from the coatings industry due to their safety, non-toxicity, lack of solvent evaporation, environmental friendliness, and good water resistance. The development of water-based polyurethane coatings has become one of the hot topics in the polyurethane coatings field in recent years.

[0004] However, existing waterborne polyurethane coatings mostly use petroleum as a raw material to prepare polyols, which consumes a large amount of petroleum resources. Furthermore, the preparation of polyols from petroleum involves complex processes and severe pollution. Natural oils are currently recognized as the only renewable alternative to petroleum, and among natural oils, vegetable oils have the most ideal performance. Therefore, introducing vegetable oil molecules into polyurethane materials using ring-opening reagents through vegetable oil polyols can not only solve the problems of petroleum resource shortages and environmental pollution, but also increase the added value of vegetable oil products. However, bio-based polyurethane coatings often have poor flame retardant properties. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a bio-based polyurethane coating and its preparation method.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of this invention is to provide a bio-based polyurethane coating, comprising, by weight, the following raw materials: 100 parts of vegetable oil polyol, 70-120 parts of isocyanate, 10-25 parts of flame retardant, 30-40 parts of organic solvent, 1-5 parts of catalyst, 10-30 parts of hydrophilic chain extender, 10-30 parts of neutralizer, and 20-40 parts of deionized water.

[0008] Preferably, the flame retardant is prepared by the following steps: adding glucosyl alcohol, tert-butyldimethylsilanol, tert-butyldimethylchlorosilane and a dipolar agent into a container, then adding a solvent and mixing evenly to obtain the flame retardant.

[0009] Preferably, the molar ratio of glucol, tert-butyldimethylchlorosilane, tert-butyldimethylsilanol, and dipolar agent is 1:1.1-1.3:1.0-1.3:1.1.

[0010] Preferably, the dipolar agent is selected from at least one of imidazole, 2-aminopyridine, and 2-aminopyrimidine; the solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, and dichloromethane.

[0011] It should be noted that 5-8 mL of solvent is used for every 1 mmol of glucol.

[0012] Preferably, the vegetable oil polyol is selected from at least one of olive oil polyol, peanut oil polyol, rapeseed oil polyol, cottonseed oil polyol, soybean oil polyol, coconut oil polyol, palm oil polyol, sesame oil polyol, corn oil polyol, and sunflower seed oil polyol; the hydroxyl value of the vegetable oil polyol is 170-200 mg KOH / g.

[0013] More preferably, the vegetable oil polyol is soybean oil polyol.

[0014] Preferably, the organic solvent is selected from at least one of acetone, ethyl acetate, dichloromethane, dichloroethane, chloroform, n-hexane, tetrahydrofuran, and carbon tetrachloride; the catalyst is diisobutyltin dilaurate.

[0015] More preferably, the organic solvent is acetone.

[0016] Preferably, the isocyanate is selected from at least one of isophorone diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate.

[0017] Preferably, the hydrophilic chain extender is selected from at least one of dihydroxy hemiester, dimethylolpropionic acid, and dimethylolbutyric acid; the neutralizing agent is selected from at least one of triethylamine, dimethylethanolamine, and N,N-dimethylcyclohexylamine.

[0018] A second aspect of this invention is to provide a method for preparing a bio-based polyurethane coating, comprising the following steps:

[0019] S1: Add plant polyols, isocyanates, flame retardants, organic solvents and catalysts to a container and mix them to obtain a prepolymer mixture;

[0020] S2: Add a hydrophilic chain extender to the prepolymer mixture in S1, and mix to obtain a polymer mixture;

[0021] S3: After the polymer mixture in S2 has cooled down, add a neutralizing agent to neutralize it, and then add deionized water to emulsify and form a polyurethane emulsion.

[0022] S4: Distill the polyurethane emulsion in S3 under reduced pressure to obtain the bio-based polyurethane coating.

[0023] Preferably, in S1, the mixing temperature is 40-70℃ and the reaction time is 1-3h; in S2, the mixing temperature is 40-70℃ and the reaction time is 2-5h; in S3, the temperature is lowered to 20-30℃.

[0024] The present invention has the following beneficial effects:

[0025] This invention uses plant oil polyols with specific hydroxyl values ​​as raw materials and reacts biomass-derived acids with organosilicon compounds to generate flame retardants. The source is stable and green. The prepared bio-based polyurethane coating has good flame retardant properties. At the same time, this invention adopts a new compounding scheme, and the prepared bio-based polyurethane coating has excellent performance. Detailed Implementation

[0026] The following detailed description, in conjunction with the present invention, illustrates the present invention and is intended to explain it, but should not be construed as limiting the present invention.

[0027] Example 1

[0028] The flame retardant is prepared by the following steps: Glucosyl alcohol, tert-butyldimethylsilanol, tert-butyldimethylchlorosilane and imidazole are added to a container in a molar ratio of 1:1.1:1.1:1.1, and then 6 mL of N,N-dimethylformamide DMF is added and mixed evenly to obtain the flame retardant.

[0029] A method for preparing a bio-based polyurethane coating includes the following steps:

[0030] S1: Mix 100 parts of vegetable oil polyol (hydroxyl value of 170 mg KOH / g), 75 parts of diphenylmethane diisocyanate (MDI), and 15 parts of the above flame retardant in 32 parts of acetone and add 2 parts of diisobutyltin dilaurate. React at 50°C for 2 hours to obtain a prepolymer mixture.

[0031] S2: Add 30 parts of hydrophilic chain extender dihydroxy half ester to the prepolymer mixture and react at 50°C for 3 hours to obtain the polymer mixture.

[0032] S3: After cooling the polymer mixture to 30°C, add 25 parts of triethylamine as a neutralizing agent to neutralize it to neutral, and add 30 parts of deionized water for high-speed shear emulsification to form a polyurethane emulsion.

[0033] S4: Remove acetone from the polyurethane emulsion by vacuum distillation to obtain a bio-based polyurethane coating.

[0034] Example 2

[0035] The flame retardant is prepared by the following steps: Glucosyl alcohol, tert-butyldimethylsilanol, tert-butyldimethylchlorosilane and 2-aminopyridine are added to a container in a molar ratio of 1:1.2:1.0:1.1, and then 6 mL of DMF is added and mixed evenly to obtain the flame retardant.

[0036] A method for preparing a bio-based polyurethane coating includes the following steps:

[0037] S1: Mix 100 parts of vegetable oil polyol (hydroxyl value of 175 mg KOH / g), 80 parts of isophorone diisocyanate (IPDI), and 18 parts of flame retardant in 35 parts of acetone and add 2 parts of diisobutyltin dilaurate. React at 50°C for 2 hours to obtain a prepolymer mixture.

[0038] S2: Add 30 parts of hydrophilic chain extender dihydroxy half ester to the prepolymer mixture and react at 50°C for 3 hours to obtain the polymer mixture.

[0039] S3: After cooling the polymer mixture to 30°C, add 25 parts of triethylamine as a neutralizing agent to neutralize it to neutral, and add 30 parts of deionized water for high-speed shear emulsification to form a polyurethane emulsion.

[0040] S4: Remove acetone from the polyurethane emulsion by vacuum distillation to obtain a bio-based polyurethane coating.

[0041] Example 3

[0042] The flame retardant is prepared by the following steps: Glucosyl alcohol, tert-butyldimethylsilanol, tert-butyldimethylchlorosilane and 2-aminopyrimidine are added to a container in a molar ratio of 1:1.3:1.2:1.1, and then 6 mL of DMF is added and mixed evenly to obtain the flame retardant.

[0043] A method for preparing a bio-based polyurethane coating includes the following steps:

[0044] S1: Mix 100 parts of vegetable oil polyol (hydroxyl value of 180 mg KOH / g), 100 parts of IPDI, and 20 parts of flame retardant in 35 parts of acetone and add 2 parts of diisobutyltin dilaurate. React at 50°C for 2 hours to obtain a prepolymer mixture.

[0045] S2: Add 30 parts of hydrophilic chain extender dihydroxypropionic acid to the prepolymer mixture and react at 50°C for 3 hours to obtain the polymer mixture.

[0046] S3: After cooling the polymer mixture to 30°C, add 28 parts of triethylamine as a neutralizing agent to neutralize it to neutral, and add 30 parts of deionized water for high-speed shear emulsification to form a polyurethane emulsion.

[0047] S4: Remove acetone from the polyurethane emulsion by vacuum distillation to obtain a bio-based polyurethane coating.

[0048] Example 4

[0049] The flame retardant is prepared by the following steps: Glucosyl alcohol, tert-butyldimethylsilanol, tert-butyldimethylchlorosilane and imidazole in a molar ratio of 1:1.1:1.3:1.1 are added to a container, and then 6 mL of DMF is added and mixed evenly to obtain the flame retardant.

[0050] A method for preparing a bio-based polyurethane coating includes the following steps:

[0051] S1: Mix 100 parts of vegetable oil polyol (hydroxyl value of 190 mg KOH / g), 105 parts of MDI, and 15 parts of flame retardant in 30 parts of acetone and add 2 parts of diisobutyltin dilaurate. React at 50°C for 2 hours to obtain a prepolymer mixture.

[0052] S2: Add 30 parts of hydrophilic chain extender dihydroxybutyric acid to the prepolymer mixture and react at 50°C for 3 hours to obtain the polymer mixture.

[0053] S3: After cooling the polymer mixture to 30°C, add 20 parts of neutralizing agent dimethylethanolamine to neutralize it, and add 30 parts of deionized water for high-speed shear emulsification to form a polyurethane emulsion.

[0054] S4: Remove acetone from the polyurethane emulsion by vacuum distillation to obtain a bio-based polyurethane coating.

[0055] Comparative Example 1

[0056] A method for preparing a bio-based polyurethane coating includes the following steps:

[0057] S1: Mix 100 parts of vegetable oil polyol (hydroxyl value of 170 mg KOH / g) and 75 parts of MDI in 32 parts of acetone and add 2 parts of diisobutyltin dilaurate. React at 50°C for 2 hours to obtain a prepolymer mixture.

[0058] S2: Add 30 parts of hydrophilic chain extender dihydroxy half ester to the prepolymer mixture and react at 50°C for 3 hours to obtain the polymer mixture.

[0059] S3: After cooling the polymer mixture to 30°C, add 25 parts of triethylamine as a neutralizing agent to neutralize it to neutral, and add 30 parts of deionized water for high-speed shear emulsification to form a polyurethane emulsion.

[0060] S4: Remove acetone from the polyurethane emulsion by vacuum distillation to obtain a bio-based polyurethane coating.

[0061] Comparative Example 2

[0062] A method for preparing a bio-based polyurethane coating includes the following steps:

[0063] S1: Mix 100 parts of vegetable oil polyol (hydroxyl value of 175 mg KOH / g), 80 parts of IPDI, and 18 parts of flame retardant TCPP in 35 parts of acetone and add 2 parts of diisobutyltin dilaurate. React at 50°C for 2 hours to obtain a prepolymer mixture.

[0064] S2: Add 30 parts of hydrophilic chain extender dihydroxy half ester to the prepolymer mixture and react at 50°C for 3 hours to obtain the polymer mixture.

[0065] S3: After cooling the polymer mixture to 30°C, add 25 parts of triethylamine as a neutralizing agent to neutralize it to neutral, and add 30 parts of deionized water for high-speed shear emulsification to form a polyurethane emulsion.

[0066] S4: Remove acetone from the polyurethane emulsion by vacuum distillation to obtain a bio-based polyurethane coating.

[0067] Comparative Example 3

[0068] A method for preparing a bio-based polyurethane coating includes the following steps:

[0069] S1: Mix 100 parts of vegetable oil polyol (hydroxyl value of 180 mg KOH / g), 100 parts of IPDI, and 20 parts of flame retardant MPP in 35 parts of acetone and add 2 parts of diisobutyltin dilaurate. React at 50°C for 2 hours to obtain a prepolymer mixture.

[0070] S2: Add 30 parts of hydrophilic chain extender dihydroxypropionic acid to the prepolymer mixture and react at 50°C for 3 hours to obtain the polymer mixture.

[0071] S3: After cooling the polymer mixture to 30°C, add 28 parts of triethylamine as a neutralizing agent to neutralize it to neutral, and add 30 parts of deionized water for high-speed shear emulsification to form a polyurethane emulsion.

[0072] S4: Remove acetone from the polyurethane emulsion by vacuum distillation to obtain a vegetable oil-based waterborne polyurethane coating.

[0073] Performance testing

[0074] The relevant determination methods for vegetable oil polyols and bio-based polyurethane coatings are as follows:

[0075] (1) The hydroxyl value of polyols in vegetable oils was determined according to GB / T 12008.3-2009;

[0076] (2) The drying time of the coating was determined according to GB / T 1728-1979(1989);

[0077] (3) The impact resistance of the coating was determined according to GB / T 1732-1993;

[0078] (4) The salt spray resistance of the coating was determined according to GB / T 1771-2007;

[0079] (5) The flame retardancy level shall be determined in accordance with GB / T 20284 and GB / T 8626.

[0080] To demonstrate the superiority of the present invention, the performance of the bio-based polyurethane coatings prepared in Examples 1-4 and Comparative Examples 1-3 was tested. The prepared coatings were applied to metal plates and tested. The performance indicators are shown in Table 1.

[0081] Table 1 Performance Indicators of Bio-based Polyurethane Coatings

[0082]

[0083] Comparative Example 1 did not add any flame retardant and obviously did not have flame retardant properties. However, as can be seen from Table 1, the flame retardant ratings of the bio-based polyurethanes prepared in Examples 1-4 are all better than those of Comparative Examples 2-3, which added conventional flame retardants. This indicates that the flame retardant provided by the present invention can improve the flame retardant properties of the coating.

[0084] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A bio-based polyurethane coating, characterized in that, By weight, it includes the following raw materials: 100 parts of vegetable oil polyol, 70-120 parts of isocyanate, 10-25 parts of flame retardant, 30-40 parts of organic solvent, 1-5 parts of catalyst, 10-30 parts of hydrophilic chain extender, 10-30 parts of neutralizer, and 20-40 parts of deionized water. The flame retardant is prepared by the following steps: adding glucosyl alcohol, tert-butyldimethylsilanol, tert-butyldimethylchlorosilane and a dipolar agent into a container, then adding a solvent and mixing evenly to obtain the flame retardant; the dipolar agent is selected from at least one of imidazole, 2-aminopyridine and 2-aminopyrimidine.

2. The bio-based polyurethane coating according to claim 1, characterized in that, The molar ratio of the glucose alcohol, tert-butyldimethylchlorosilane, tert-butyldimethylsilanol, and the dipolar agent is 1:1.1-1.3:1.0-1.3:1.

1.

3. The bio-based polyurethane coating according to claim 2, characterized in that, The solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, and dichloromethane.

4. The bio-based polyurethane coating according to claim 1, characterized in that, The plant oil polyol is selected from at least one of olive oil polyol, peanut oil polyol, rapeseed oil polyol, cottonseed oil polyol, soybean oil polyol, coconut oil polyol, palm oil polyol, sesame oil polyol, corn oil polyol, and sunflower seed oil polyol; the hydroxyl value of the plant oil polyol is 170-200 mg KOH / g.

5. The bio-based polyurethane coating according to claim 1, characterized in that, The organic solvent is selected from at least one of acetone, ethyl acetate, dichloromethane, dichloroethane, chloroform, n-hexane, tetrahydrofuran, and carbon tetrachloride; the catalyst is diisobutyltin dilaurate.

6. The bio-based polyurethane coating according to claim 1, characterized in that, The isocyanate is selected from at least one of isophorone diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate.

7. The bio-based polyurethane coating according to claim 1, characterized in that, The hydrophilic chain extender is selected from at least one of dihydroxy halogen, dimethylolpropionic acid, and dimethylolbutyric acid; the neutralizing agent is selected from at least one of triethylamine, dimethylethanolamine, and N,N-dimethylcyclohexylamine.

8. A method for preparing the bio-based polyurethane coating according to any one of claims 1-7, characterized in that, Includes the following steps: S1: Add vegetable oil polyol, isocyanate, flame retardant, organic solvent and catalyst to a container and mix to obtain a prepolymer mixture; S2: Add a hydrophilic chain extender to the prepolymer mixture in S1, and mix to obtain a polymer mixture; S3: After the polymer mixture in S2 has cooled down, add a neutralizing agent to neutralize it, and then add deionized water to emulsify and form a polyurethane emulsion. S4: Distill the polyurethane emulsion in S3 under reduced pressure to obtain the bio-based polyurethane coating.

9. The preparation method according to claim 8, characterized in that, In step S1, the mixing temperature is 40-70℃ and the reaction time is 1-3 h; in step S2, the mixing temperature is 40-70℃ and the reaction time is 2-5 h; in step S3, the temperature is lowered to 20-30℃.

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