Bio-based polyurethane coating and preparation method thereof

Abstract

The invention discloses a bio-based polyurethane coating and a preparation method thereof, and belongs to the technical field of coatings. The bio-based polyurethane coating comprises the following raw materials in parts by weight: 100 parts of vegetable oil polyol, 70-120 parts of isocyanate, 10-25 parts of a flame retardant, 30-40 parts of an organic solvent, 1-5 parts of a catalyst, 10-30 parts of a hydrophilic chain extender, 10-30 parts of a neutralizer and 20-40 parts of deionized water. The preparation method comprises the following steps: adding plant polyol, isocyanate, a flame retardant, an organic solvent and a catalyst into a container, mixing and reacting to obtain a prepolymer mixed solution, then adding a hydrophilic chain extender, mixing and reacting to obtain a polymer mixed solution, cooling, then adding a neutralizer for neutralizing, then adding deionized water for emulsifying to form a polyurethane emulsion, and finally adding a curing agent for curing. And performing reduced pressure distillation to obtain the bio-based polyurethane coating. According to the invention, biomass-sourced acid reacts with the organosilicon compound to generate the flame retardant, and the prepared bio-based polyurethane coating has good flame retardant property.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and in particular relates to a bio-based polyurethane coating and a preparation method thereof. Background Art

[0002] Polyurethane is a polymer with repeating structural units of carbamate segments made by the reaction of isocyanate and polyol. Polyurethane products are divided into two categories: foamed products and non-foamed products. Foamed products include soft, hard, and semi-hard polyurethane foam plastics; non-foamed products include coatings, adhesives, synthetic leather, elastomers, and elastic fibers. Polyurethane materials have excellent performance, a wide range of uses, and a wide variety of products, among which polyurethane coatings are the most widely used.

[0003] In recent years, with the increase of people's environmental awareness and their concern for their own health, coupled with the strict requirements of environmental regulations on the emission of volatile organic compounds (VOC) and the content of harmful solvents, the application of polyurethane coatings containing solvents and organic fillers has been greatly restricted, prompting polyurethane coatings to develop in the direction of water-based, powdered and high solid content. Among them, water-based polyurethane coatings use water as a dispersion medium and are highly valued by the coating industry because of their safety, non-toxicity, no solvent volatilization, environmental friendliness, and good water resistance. The development of water-based polyurethane coatings has become one of the hot spots in the field of polyurethane coatings in recent years.

[0004] However, the existing waterborne polyurethane coatings mostly use petroleum as raw material to prepare polyols, which consumes a large amount of petroleum resources, and the use of petroleum to prepare polyols has problems such as complex processes and serious pollution. Natural oils are currently recognized and the only renewable petroleum substitute, and among natural oils, vegetable oils have the best performance. Therefore, by using vegetable oil polyols to introduce vegetable oil molecules into polyurethane materials with ring-opening reagents, it can not only solve the problems of shortage of petroleum resources 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] In view of the deficiencies in the prior art, the object of the present invention is to provide a bio-based polyurethane coating and a preparation method thereof.

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

[0007] The first aspect of the present invention is to provide a bio-based polyurethane coating, which includes the following raw materials, by weight: 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 glucitol, tert-butyldimethylsilanol, tert-butyldimethylchlorosilane and a dipole agent into a container, then adding a solvent, and mixing them uniformly to obtain the flame retardant.

[0009] Preferably, the molar ratio of glucitol, tert-butyldimethylsilyl chloride, tert-butyldimethylsilanol and the dipole agent is 1:1.1-1.3:1.0-1.3:1.1.

[0010] Preferably, the dipole agent is selected from at least one of imidazole, 2-aminopyridine and 2-aminopyrimidine; and 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 the solvent was used per 1 mmol of glucitol.

[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 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; and 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 half ester, dimethylol propionic acid, and dimethylol butyric acid; and the neutralizer is selected from at least one of triethylamine, dimethylethanolamine, and N,N-dimethylcyclohexylamine.

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

[0019] S1: adding plant polyol, isocyanate, flame retardant, organic solvent and catalyst into a container, mixing and reacting to obtain a prepolymer mixture;

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

[0021] S3: After the polymer mixture in S2 is cooled, a neutralizing agent is added for neutralization, and then deionized water is added for emulsification to form a polyurethane emulsion;

[0022] S4: The polyurethane emulsion in S3 is distilled under reduced pressure to obtain a bio-based polyurethane coating.

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

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

[0025] The present invention adopts vegetable oil polyols with specific hydroxyl values ​​as raw materials, uses biomass-derived acids to react with organosilicon compounds to generate flame retardants, which have a stable and green source. The prepared bio-based polyurethane coating has good flame retardant properties. At the same time, the present invention adopts a new compounding scheme, and the prepared bio-based polyurethane coating has excellent performance. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below. The embodiments described are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0027] Example 1

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

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

[0030] S1: 100 parts of vegetable oil polyol (hydroxyl value: 170 mg KOH / g), 75 parts of diphenylmethane diisocyanate MDI, 15 parts of the above flame retardant were mixed in 32 parts of acetone, and 2 parts of diisobutyltin dilaurate were added, and the mixture was reacted at 50° C. for 2 h 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 a polymer mixture.

[0032] S3: After cooling the polymer mixture to 30°C, 25 parts of a neutralizing agent, triethylamine, is added to neutralize the mixture until it is neutral, and 30 parts of deionized water are added to emulsify the mixture at high speed to form a polyurethane emulsion.

[0033] S4: The polyurethane emulsion is subjected to reduced pressure distillation to remove acetone to obtain a bio-based polyurethane coating.

[0034] Example 2

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

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

[0037] S1: 100 parts of vegetable oil polyol (hydroxyl value: 175 mg KOH / g), 80 parts of isophorone diisocyanate IPDI, 18 parts of flame retardant were mixed in 35 parts of acetone, and 2 parts of diisobutyltin dilaurate were added, and the mixture was reacted at 50°C for 2h 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 a polymer mixture.

[0039] S3: After cooling the polymer mixture to 30°C, 25 parts of a neutralizing agent, triethylamine, is added to neutralize the mixture until it is neutral, and 30 parts of deionized water are added to emulsify the mixture at high speed to form a polyurethane emulsion.

[0040] S4: The polyurethane emulsion is subjected to reduced pressure distillation to remove acetone to obtain a bio-based polyurethane coating.

[0041] Example 3

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

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

[0044] S1: 100 parts of vegetable oil polyol (hydroxyl value: 180 mg KOH / g), 100 parts of IPDI, and 20 parts of flame retardant were mixed in 35 parts of acetone, and 2 parts of diisobutyltin dilaurate were added, and the mixture was reacted at 50° C. for 2 h to obtain a prepolymer mixture.

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

[0046] S3: After cooling the polymer mixture to 30°C, 28 parts of a neutralizing agent, triethylamine, is added to neutralize the mixture to neutrality, and 30 parts of deionized water are added to emulsify the mixture at high speed to form a polyurethane emulsion.

[0047] S4: removing acetone from the polyurethane emulsion under reduced pressure to obtain a bio-based polyurethane coating.

[0048] Example 4

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

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

[0051] S1: 100 parts of vegetable oil polyol (hydroxyl value: 190 mg KOH / g), 105 parts of MDI, and 15 parts of flame retardant were mixed in 30 parts of acetone, and 2 parts of diisobutyltin dilaurate were added, and the mixture was reacted at 50° C. for 2 h 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 a polymer mixture.

[0053] S3: After cooling the polymer mixture to 30°C, 20 parts of a neutralizing agent, dimethylethanolamine, is added to neutralize the mixture until it is neutral, and 30 parts of deionized water are added to emulsify the mixture at high speed shearing to form a polyurethane emulsion.

[0054] S4: removing acetone from the polyurethane emulsion under reduced pressure to obtain a bio-based polyurethane coating.

[0055] Comparative Example 1

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

[0057] S1: 100 parts of vegetable oil polyol (hydroxyl value: 170 mg KOH / g) and 75 parts of MDI were mixed in 32 parts of acetone, and 2 parts of diisobutyltin dilaurate were added, and the mixture was reacted at 50° C. for 2 h 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 a polymer mixture.

[0059] S3: After cooling the polymer mixture to 30°C, 25 parts of a neutralizing agent, triethylamine, is added to neutralize the mixture until it is neutral, and 30 parts of deionized water are added to emulsify the mixture at high speed to form a polyurethane emulsion.

[0060] S4: removing acetone from the polyurethane emulsion under reduced pressure to obtain a bio-based polyurethane coating.

[0061] Comparative Example 2

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

[0063] S1: 100 parts of vegetable oil polyol (hydroxyl value: 175 mg KOH / g), 80 parts of IPDI, 18 parts of flame retardant TCPP were mixed in 35 parts of acetone, 2 parts of diisobutyltin dilaurate were added, and the mixture was reacted at 50°C for 2h 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 a polymer mixture.

[0065] S3: After cooling the polymer mixture to 30°C, 25 parts of a neutralizing agent, triethylamine, is added to neutralize the mixture until it is neutral, and 30 parts of deionized water are added to emulsify the mixture at high speed to form a polyurethane emulsion.

[0066] S4: removing acetone from the polyurethane emulsion under reduced pressure to obtain a bio-based polyurethane coating.

[0067] Comparative Example 3

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

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

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

[0071] S3: After cooling the polymer mixture to 30°C, 28 parts of a neutralizing agent, triethylamine, is added to neutralize the mixture to neutrality, and 30 parts of deionized water are added to emulsify the mixture at high speed to form a polyurethane emulsion.

[0072] S4: The polyurethane emulsion is subjected to reduced pressure distillation to remove acetone to obtain a vegetable oil-based waterborne polyurethane coating.

[0073] Performance Testing

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

[0075] (1) Measure the hydroxyl value of vegetable oil polyols according to GB / T 12008.3-2009;

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

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

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

[0079] (5) Flame retardant grade is determined according to GB / T 20284 and GB / T 8626.

[0080] In order 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 on metal plates for testing. The performance indicators are shown in Table 1.

[0081] Table 1 Performance indicators of bio-based polyurethane coatings

[0082]

[0083] No flame retardant was added to Comparative Example 1, which obviously does not have flame retardant properties. However, it can be seen from Table 1 that the flame retardant grades of the bio-based polyurethanes prepared in Examples 1-4 are better than those of Comparative Examples 2-3 to which conventional flame retardants were added, indicating that the flame retardant provided by the present invention can improve the flame retardant properties of the coating.

[0084] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A bio-based polyurethane coating, characterized in that: The raw materials are as follows, calculated by weight: 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.

2. The bio-based polyurethane coating according to claim 1, characterized in that The flame retardant is prepared by the following steps: adding glucose alcohol, tert-butyldimethylsilanol, tert-butyldimethylchlorosilane and a dipole agent into a container, then adding a solvent, and mixing them uniformly to obtain the flame retardant.

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

1.

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

5. The bio-based polyurethane coating according to claim 1, characterized in that 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 oil polyol; the hydroxyl value of the vegetable oil polyol is 170-200 mg KOH / g.

6. 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; and the catalyst is diisobutyltin dilaurate.

7. 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.

8. The bio-based polyurethane coating according to claim 1, characterized in that The hydrophilic chain extender is selected from at least one of dihydroxy half ester, dimethylol propionic acid and dimethylol butyric acid; the neutralizer is selected from at least one of triethylamine, dimethylethanolamine and N,N-dimethylcyclohexylamine.

9. A method for preparing the bio-based polyurethane coating according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: adding plant polyol, isocyanate, flame retardant, organic solvent and catalyst into a container, mixing and reacting to obtain a prepolymer mixture; S2: adding a hydrophilic chain extender to the prepolymer mixture in S1, mixing and reacting to obtain a polymer mixture; S3: After the polymer mixture in S2 is cooled, a neutralizing agent is added for neutralization, and then deionized water is added for emulsification to form a polyurethane emulsion; S4: The polyurethane emulsion in S3 is distilled under reduced pressure to obtain a bio-based polyurethane coating.

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

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