Functional coating based on bio-based waterborne polyurethane and preparation method of functional coating

Abstract

The invention relates to the technical field of coatings, and discloses a functional coating based on bio-based waterborne polyurethane and a preparation method thereof.The functional coating is formed by taking bio-based waterborne polyurethane emulsion as a film forming matter and taking ammonium polyphosphate and the like as auxiliary materials through mixing, an isocyanate monomer is used as a hard segment and is subjected to cross-linking polymerization with a chain extender and a molybdenum disulfide modified material under the action of a catalyst, polyhydroxy polymalic acid is used as a biomass raw material, has water solubility and conforms to the environment-friendly concept, and polyhydroxy polymalic acid is used as a soft segment, so that the molecular chain density of the prepared polyurethane is greatly increased, and the mechanical property of the polyurethane is improved. The molybdenum disulfide modified material is added into polyurethane, so that a coating formed by curing the coating has higher density, the mechanical properties such as hardness of the coating are improved, the molybdenum disulfide modified material can participate in chain extension of polyurethane, organic combination of nano molybdenum disulfide and polyurethane is realized, and the wear resistance and mechanical strength of the coating are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to a functional coating based on bio-based waterborne polyurethane and a preparation method thereof. BACKGROUND

[0002] As one of the common materials, organic coatings can be seen everywhere in daily work and life. At present, organic coatings are generally divided into epoxy resin coatings, acrylic resin coatings and polyurethane coatings, among which polyurethane coatings have a relatively wider application range due to their excellent adhesion, solvent resistance and corrosion resistance. However, traditional solvent-based polyurethane coatings will produce serious environmental pollution due to the continuous volatilization of solvents during use, which does not meet the environmental protection concept. Waterborne polyurethane coatings mainly use water as the dispersion medium, so the emission is low and they are relatively more environmentally friendly. However, the problem of waterborne polyurethane coatings is that they have poor wear resistance and poor comprehensive performance such as mechanical strength and hardness. Therefore, it is of great significance to improve the comprehensive performance of waterborne polyurethane coatings for further development.

[0003] At present, the method of filling modification with inorganic fillers is relatively common, but there are interface problems between inorganic substances and polyurethane, and effective interface connection between them is difficult to form, which makes it difficult for inorganic fillers to truly exert their own advantages. In addition, the performance of waterborne polyurethane coatings can be improved by designing the polyurethane molecular chain and increasing the density of the polyurethane molecular chain. Based on this, the present application provides a functional coating based on bio-based waterborne polyurethane, which can solve the problems existing in the prior art. SUMMARY

[0004] In order to solve the problems mentioned in the background art, the purpose of the present application is to provide a functional coating based on bio-based waterborne polyurethane and a preparation method thereof.

[0005] The purpose of the present application can be achieved by the following technical solutions:

[0006] A functional coating based on bio-based waterborne polyurethane, comprising the following raw materials in parts by weight:

[0007] 65-85 parts of bio-based waterborne polyurethane emulsion, 3-5 parts of ammonium polyphosphate, 5-10 parts of aluminum hydroxide, 0.5-1.5 parts of defoaming agent and 0.5-1 part of antioxidant.

[0008] As a further scheme of the present application, the preparation method of the bio-based waterborne polyurethane emulsion comprises the following steps:

[0009] Step one, the polyhydroxy poly malic acid is added into butanone, after mechanical stirring and mixing, the temperature is increased to 70-75℃, then the isocyanate monomer and catalyst are added into the formed mixture, after the addition, the stirring is continued for 2-4h, then the chain extender and molybdenum disulfide modified material are continuously added, after the addition, the stirring is continued for 6-9h, and the polyurethane polymer material is formed;

[0010] Step two, the temperature is reduced to 40-50℃, then triethylamine is added for neutralization, after stirring for 20-30min, the heating is stopped, and then the deionized water is added, the stirring and emulsification are carried out for 1-2h, then butanone is evaporated, and the bio-based waterborne polyurethane emulsion is prepared.

[0011] As a further scheme of the present application, the preparation method of the polyhydroxy poly malic acid is as follows:

[0012] The β-poly malic acid is added into 1,4-dioxane, after stirring and mixing, the glycidol is added into the formed mixture, after the addition, the nitrogen protection is carried out, the temperature is increased to 60-70℃, then the phase transfer catalyst is added into the mixture, after the addition, the stirring and heat preservation are continued for 6-12h, then the solvent is evaporated, the temperature is reduced for discharging, the product is collected, and after the post-treatment process, the polyhydroxy poly malic acid is prepared.

[0013] As a further scheme of the present application, the number average molecular weight of the β-poly malic acid is 2000.

[0014] As a further scheme of the present application, the phase transfer catalyst is any one of tetrabutylammonium chloride, tetramethylammonium chloride, tetramethylammonium bromide, tetrabutylammonium hydrogen sulfate or tetrabutylammonium bromide.

[0015] Specifically, in the above technical scheme, the β-poly malic acid and glycidol are used as raw materials, the active carboxyl substituent in the structure of each other can be subjected to ring-opening esterification reaction with the epoxy substituent, since the additional hydroxyl functional group is generated in the reaction process, a large number of active hydroxyl substituents can be introduced into the structure of the β-poly malic acid, and the polyhydroxy poly malic acid is prepared.

[0016] As a further scheme of the present application, the preparation method of the molybdenum disulfide modified material includes the following steps:

[0017] Step SS1, the nanometer molybdenum disulfide is ultrasonically dispersed in N,N-dimethylformamide, then the epoxidation modification reagent and stannous chloride are added into the formed dispersion, after the addition, the stirring is uniform, then the temperature is increased to 130-140℃, the stirring is continued at the temperature for 6-9h, then the heating is stopped, the temperature is reduced for discharging, the product is centrifuged, and the functionalized molybdenum disulfide is prepared.

[0018] Step SS2, the functionalized molybdenum disulfide is added to the sulfuric acid solution, ultrasonic dispersion is uniform, then the temperature is increased to 90-100 DEG C, and after 0.5-1.5 h of incubation and stirring, heating is stopped, and the temperature is decreased to discharge, so that the molybdenum disulfide modified material is prepared.

[0019] As a further scheme of the present application, the epoxidation modification reagent is ethylene glycol diglycidyl ether or dipropylene glycol diglycidyl ether.

[0020] As a further scheme of the present application, the pH value of the sulfuric acid solution is 2-3.

[0021] Specifically, in the above technical scheme, first, the epoxy group at one end of the epoxidation reagent structure is subjected to ring-opening addition with the hydroxyl group on the surface of the nano molybdenum disulfide by using stannous chloride as a catalyst, so that the molybdenum disulfide containing an epoxy functional group on the surface, i.e., the functionalized molybdenum disulfide, is prepared, then the epoxy group is subjected to ring-opening by using sulfuric acid, so that one equivalent of the epoxy group is converted into two equivalents of active hydroxyl substituents, thereby a large number of active hydroxyl substituents are modified on the surface of the nano molybdenum disulfide.

[0022] As a further scheme of the present application, the isocyanate monomer is pentamethylene diisocyanate; and the catalyst is dibutyltin dilaurate or stannous octoate.

[0023] A preparation method of a functional coating based on a bio-based waterborne polyurethane, comprising the following steps:

[0024] In the first step, the raw materials are weighed and prepared according to the weight fraction;

[0025] In the second step, the bio-based waterborne polyurethane emulsion, ammonium polyphosphate, aluminum hydroxide, and antioxidant are added to a high-speed mixer, and mechanically stirred and mixed at a stirring rate of 500-1000 r / min for 1-2 h, the stirring rate is adjusted to 100-200 r / min, the defoaming agent is continuously added, after the addition is completed, the stirring is stopped after 10-20 min of stirring, and the material is discharged, so that the functional coating is prepared.

[0026] The present application has the following advantages:

[0027] In the present application, the poly malic acid containing a large number of active hydroxyl substituents in the structure is prepared as the soft segment of the polyurethane molecular chain, on the one hand, the poly malic acid is a biomass raw material and has water solubility, which meets the environmental protection concept, and on the other hand, the existence of a large number of hydroxyl groups will form a crosslinked network structure in the subsequent polymerization process with the isocyanate monomer, so that the polyurethane molecular chain density is greatly increased, so that the coating layer formed by the curing of the coating has higher compactness, thereby being beneficial to the improvement of the hardness and other mechanical strengths of the coating layer.

[0028] The present application realizes the interface organic combination of nano molybdenum disulfide and polyurethane molecular chain by preparing nano molybdenum disulfide with a large number of active hydroxyl substituents on the surface to participate in the chain extension process of polyurethane molecular chain, so that the nano molybdenum disulfide can be fully and uniformly dispersed in the coating, and the wear resistance and mechanical strength of the coating can be effectively improved by using its own advantages.

[0029] Of course, it is not necessary for any product embodying the present application to achieve all of the above advantages simultaneously. DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be described clearly and completely below in combination with embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0031] Preparation Example 1

[0032] Preparation of bio-based waterborne polyurethane emulsion:

[0033] Step one, 15g of polyhydroxyl poly-malic acid is added to 100mL butanone, and after mechanical stirring and uniform mixing, the temperature is raised to 75℃, then 8g of pentamethylene diisocyanate and 0.1g of dibutyltin dilaurate are added to the formed mixture, after the addition, the stirring is continued for 3h, then 0.8g of chain extender ethylenediamine and 0.5g of modified molybdenum disulfide are continuously added, after the addition is completed, the stirring is continued for 8h to form polyurethane polymer;

[0034] Step two, the temperature is reduced to 45℃, and triethylamine is added for neutralization, after stirring for 25min, the heating is stopped, and the mixture is naturally cooled, then 60mL of deionized water is added, and the mixture is stirred and emulsified for 1h, then butanone is evaporated to obtain the bio-based waterborne polyurethane emulsion.

[0035] The preparation method of the polyhydroxyl poly-malic acid is as follows:

[0036] 1.5g of β-poly-malic acid with a number average molecular weight of 2000 is added to 1,4-dioxane, and after stirring and uniform mixing, 0.3g of glycidol is added to the formed mixture, after the addition, nitrogen protection is carried out, the temperature is raised to 65℃, then 0.1g of tetrabutylammonium bromide is added to the mixture, after the addition, the temperature is continuously maintained and stirred for 9h, then the solvent is evaporated, the temperature is lowered to discharge the product, and after the post-treatment process, the polyhydroxyl poly-malic acid is obtained.

[0037] The preparation method of the modified molybdenum disulfide includes the following steps:

[0038] Step SS1, 0.5 g of nano-molybdenum disulfide was ultrasonically dispersed in N,N-dimethylformamide, then 1.2 g of ethylene glycol diglycidyl ether and 0.01 g of stannous chloride were added to the formed dispersion, after the addition was completed, the mixture was stirred uniformly, then the temperature was raised to 135°C, and after continuous stirring at this temperature for 8 h, the heating was stopped, the temperature was lowered, the product was centrifuged, and functional molybdenum disulfide was obtained.

[0039] Step SS2, 0.6 g of functional molybdenum disulfide was added to 80 mL of sulfuric acid solution with a pH value of 2, and ultrasonically dispersed uniformly, then the temperature was raised to 95°C, and after 1 h of stirring under heat preservation, the heating was stopped, the temperature was lowered, and the molybdenum disulfide modified material was obtained.

[0040] Example 1

[0041] A functional coating based on bio-based waterborne polyurethane, according to weight fraction, includes the following raw materials:

[0042] Bio-based waterborne polyurethane emulsion 65 parts, ammonium polyphosphate 3 parts, aluminum hydroxide 5 parts, defoaming agent 0.5 parts, antioxidant 0.5 parts.

[0043] The preparation method of the functional coating includes the following steps:

[0044] First step, each raw material is weighed according to the weight fraction and prepared;

[0045] Second step, the bio-based waterborne polyurethane emulsion, ammonium polyphosphate, aluminum hydroxide, antioxidant are added to a high-speed stirrer, mechanically stirred and mixed at a stirring rate of 500 r / min for 2 h, the stirring rate is adjusted to 100 r / min, the defoaming agent is continuously added, after the addition is completed, the mixture is stirred for 20 min, then the stirring is stopped, and the functional coating is obtained.

[0046] The preparation method of the bio-based waterborne polyurethane emulsion is shown in the preparation example; the defoaming agent is BYK-057; the antioxidant is antioxidant 1076, and the following are the same.

[0047] Example 2

[0048] A functional coating based on bio-based waterborne polyurethane, according to weight fraction, includes the following raw materials:

[0049] Bio-based waterborne polyurethane emulsion 80 parts, ammonium polyphosphate 4 parts, aluminum hydroxide 8 parts, defoaming agent 1 part, antioxidant 0.8 part.

[0050] The preparation method of the functional coating includes the following steps:

[0051] First step, each raw material is weighed according to the weight fraction and prepared;

[0052] Second step, the bio-based waterborne polyurethane emulsion, ammonium polyphosphate, aluminum hydroxide, antioxidant is added to the high-speed blender, and is mechanically stirred and mixed at a stirring rate of 800 r / min for 1.5 h. The stirring rate is adjusted to 150 r / min, and the defoaming agent is continuously added. After the addition is completed, stirring is performed for 15 min, then the stirring is stopped, and the product is discharged, thereby obtaining the functional coating.

[0053] Example 3

[0054] A bio-based waterborne polyurethane functional coating, according to the weight fraction, comprises the following raw materials:

[0055] The bio-based waterborne polyurethane emulsion 85 parts, ammonium polyphosphate 3 parts, aluminum hydroxide 10 parts, defoaming agent 1.5 parts, antioxidant 1 part.

[0056] The preparation method of the functional coating comprises the following steps:

[0057] First step, each raw material is weighed according to the weight fraction and prepared;

[0058] Second step, the bio-based waterborne polyurethane emulsion, ammonium polyphosphate, aluminum hydroxide, antioxidant is added to the high-speed blender, and is mechanically stirred and mixed at a stirring rate of 800 r / min for 1.5 h. The stirring rate is adjusted to 150 r / min, and the defoaming agent is continuously added. After the addition is completed, stirring is performed for 15 min, then the stirring is stopped, and the product is discharged, thereby obtaining the functional coating.

[0059] Comparative example 1

[0060] A bio-based waterborne polyurethane functional coating, according to the weight fraction, comprises the following raw materials:

[0061] The bio-based waterborne polyurethane emulsion 85 parts, ammonium polyphosphate 3 parts, aluminum hydroxide 10 parts, defoaming agent 1.5 parts, antioxidant 1 part.

[0062] The preparation method of the functional coating comprises the following steps:

[0063] First step, each raw material is weighed according to the weight fraction and prepared;

[0064] Second step, the bio-based waterborne polyurethane emulsion, ammonium polyphosphate, aluminum hydroxide, antioxidant is added to the high-speed blender, and is mechanically stirred and mixed at a stirring rate of 800 r / min for 1.5 h. The stirring rate is adjusted to 150 r / min, and the defoaming agent is continuously added. After the addition is completed, stirring is performed for 15 min, then the stirring is stopped, and the product is discharged, thereby obtaining the functional coating.

[0065] The preparation method of the bio-based waterborne polyurethane emulsion is different from that of the preparation example, in which the polyhydroxyl poly-malic acid is replaced by polyethylene glycol with a number average molecular weight of 2000, and the others are the same.

[0066] Comparative Example 2

[0067] A functional coating based on bio-based waterborne polyurethane, comprising the following raw materials in parts by weight:

[0068] Bio-based waterborne polyurethane emulsion 80 parts, ammonium polyphosphate 4 parts, aluminum hydroxide 8 parts, defoaming agent 1 part, antioxidant 0.8 part.

[0069] The preparation method of the functional coating comprises the following steps:

[0070] First, each raw material is weighed and prepared according to the weight fraction;

[0071] Second, the bio-based waterborne polyurethane emulsion, ammonium polyphosphate, aluminum hydroxide, and antioxidant are added to a high-speed mixer, and mechanically stirred and mixed at a stirring rate of 800 r / min for 1.5 h. The stirring rate is adjusted to 150 r / min, and the defoaming agent is continuously added. After stirring for 15 min, stop stirring, and discharge to obtain the functional coating.

[0072] The difference between the preparation method of the bio-based waterborne polyurethane emulsion and the preparation example is that the molybdenum disulfide modified material is replaced by unmodified nano molybdenum disulfide, and the others are the same.

[0073] Performance test

[0074] The functional coatings in the examples and comparative examples are made into coating samples that meet the test specifications, and various performance tests are carried out, and the results are recorded in the following table:

[0075] Table 1-Test results

[0076]

[0077]

[0078] The wear resistance is tested according to the standard GB / T 1768-2006;

[0079] The impact performance is tested according to the standard GB / T 1732-2020;

[0080] The hardness is tested according to the standard GB / T 6739-2006.

[0081] It can be analyzed from the test results that the coating formed after curing of the coating prepared in the embodiment of the application has good mechanical properties and excellent wear resistance, and after replacing the polyhydroxy poly-malic acid in the bio-based waterborne polyurethane emulsion with conventional soft satin molecular chain polyethylene glycol, the cross-linking density of the molecular chain is reduced, resulting in a decrease in the density of the coating, and the mechanical properties and wear resistance of the coating are negatively affected to different degrees. After replacing the molybdenum disulfide modified material with unmodified nano molybdenum disulfide, due to the problem of interface incompatibility, the nano molybdenum disulfide is difficult to form stable dispersion effect, so it cannot efficiently exert its own enhancement advantage, and therefore the various performances are greatly reduced.

[0082] The principles and implementation manners of the present application are described herein by using specific examples, and the above examples are only used to help understand the method of the present application and its core idea, including the best mode, and also enable any person skilled in the art to practice the present application, including implementing any combined method. It should be noted that, for those skilled in the art, without departing from the principles of the present application, some improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application. The scope of the patent protection of the present application is defined by the claims, and can include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.

[0083] The above examples are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements will not cause the essence of the corresponding technical solution to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A functional coating based on bio-based waterborne polyurethane, characterized in that: According to parts by weight, the following raw materials are included: 65-85 parts of bio-based water-based polyurethane emulsion, 3-5 parts of ammonium polyphosphate, 5-10 parts of aluminum hydroxide, 0.5-1.5 parts of defoaming agent, and 0.5-1 part of antioxidant.

2. The functional coating based on bio-based waterborne polyurethane according to claim 1, characterized in that: The preparation method of the bio-based waterborne polyurethane emulsion comprises the following steps: Step 1: Add polyhydroxy polymalic acid to butanone, stir mechanically to mix evenly, heat to 70-75°C, then add isocyanate monomer and catalyst to the resulting mixture, continue stirring for 2-4 hours after addition, then continue adding chain extender and molybdenum disulfide modifier, continue stirring and polymerizing for 6-9 hours after addition, to form a polyurethane polymer; Step 2: Lower the temperature to 40-50°C, add triethylamine for neutralization, stir for 20-30 minutes, stop heating, allow to cool naturally, add deionized water, stir and emulsify for 1-2 hours, evaporate and remove butanone, and obtain a bio-based waterborne polyurethane emulsion.

3. The functional coating based on bio-based waterborne polyurethane according to claim 2, characterized in that: The preparation method of the polyhydroxy polymalic acid is as follows: β-polymalic acid is added to 1,4-dioxane, stirred and mixed evenly, and then glycidol is added to the resulting mixed solution. After the addition is completed, nitrogen is introduced for protection, and the temperature is raised to 60-70°C. Then, a phase transfer catalyst is added to the mixed solution. After the addition is completed, the mixture is kept warm and stirred for 6-12 hours, and the solvent is evaporated to remove. The temperature is lowered and the product is collected. After post-processing, polyhydroxy polymalic acid can be obtained.

4. The functional coating based on bio-based waterborne polyurethane according to claim 3, characterized in that: The number average molecular weight of the β-polymalic acid is 2000.

5. The functional coating based on bio-based waterborne polyurethane according to claim 3, characterized in that: The phase transfer catalyst is any one of tetrabutylammonium chloride, tetramethylammonium chloride, tetramethylammonium bromide, tetrabutylammonium hydrogen sulfate or tetrabutylammonium bromide.

6. The functional coating based on bio-based waterborne polyurethane according to claim 2, characterized in that: The preparation method of the molybdenum disulfide modified material comprises the following steps: Step SS1, ultrasonically dispersing nano-molybdenum disulfide in N,N-dimethylformamide, then adding an epoxidation modification agent and stannous chloride to the formed dispersion, stirring evenly after the addition, then raising the temperature to 130-140°C, stirring continuously at this temperature for 6-9 hours, stopping heating, cooling the material, and centrifuging the product to obtain functionalized molybdenum disulfide; Step SS2: Add functionalized molybdenum disulfide to sulfuric acid solution and disperse it evenly by ultrasonication. Then, raise the temperature to 90-100° C., keep stirring for 0.5-1.5 hours, stop heating, cool and discharge the material to obtain a modified molybdenum disulfide material.

7. The functional coating based on bio-based waterborne polyurethane according to claim 6, characterized in that: The epoxidation modification agent is ethylene glycol diglycidyl ether or dipropylene glycol diglycidyl ether.

8. The functional coating based on bio-based waterborne polyurethane according to claim 6, characterized in that: The pH value of the sulfuric acid solution is 2-3.

9. The functional coating based on bio-based waterborne polyurethane according to claim 2, characterized in that: The isocyanate monomer is pentamethylene diisocyanate; and the catalyst is dibutyltin dilaurate or stannous octoate.

10. A method for preparing a functional coating based on bio-based waterborne polyurethane according to claim 1, characterized in that: The following steps are involved: The first step is to weigh and prepare all the raw materials according to their weight; In the second step, the bio-based waterborne polyurethane emulsion, ammonium polyphosphate, aluminum hydroxide and antioxidant are added to a high-speed mixer, and mechanically stirred and mixed at a stirring rate of 500-1000 r / min for 1-2 hours. The stirring rate is adjusted to 100-200 r / min, and the defoaming agent is continued to be added. After the addition is completed, stirring is completed for 10-20 minutes, and then stirring is stopped and the material is discharged to obtain the functional coating.

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