Cottonseed oil-based polyurethane coating based on micro-flow field technology as well as preparation method and application thereof

Abstract

The invention belongs to the field of coating preparation and relates to a cottonseed oil-based polyurethane coating based on a micro-flow field technology as well as a preparation method and application thereof. The preparation method comprises the following steps: polymerizing epoxidized cottonseed oil and isocyanate through a micro-flow field reaction device under the action of an initiator to prepare a cottonseed oil-based polyurethane prepolymer; and uniformly mixing the cottonseed oil-based polyurethane prepolymer with the color paste system to obtain the cottonseed oil-based polyurethane coating based on the micro-flow field technology. The cottonseed oil-based polyurethane coating prepared by the invention has excellent mechanical properties and chemical corrosion resistance, is rich in color, good in decorative effect and wide in application, and has very good economic and social benefits.

Description

Technical Field

[0001] The invention belongs to the field of coating preparation, and relates to a cottonseed oil-based polyurethane coating based on micro-flow field technology, and a preparation method and application thereof. Background Art

[0002] Polyurethane is known as the "fifth largest plastic in the world". It has excellent performance in thermal stability, mechanical properties, waterproofness, corrosion resistance and weather resistance. It is prepared into mid-end products such as sealants, hard (soft) foams, coatings, artificial leather, thermal insulation materials, etc. and used in aerospace, automobiles, furniture, ships, building materials and other industries. Traditional polyurethanes are mostly synthesized from petrochemical resources, and the raw materials are mostly toxic and hazardous chemicals. In recent years, petrochemical resources have become increasingly scarce, and environmental protection requirements have become increasingly stringent. Bio-based polyurethane has become a research hotspot due to its environmental friendliness and renewable advantages. The main raw materials of bio-based polyurethane come from vegetable oils, lignin, starch, fibers, etc. Among them, vegetable oils are increasingly attracting attention because they are renewable resources with large output and low prices.

[0003] Vegetable oils mainly include castor oil, corn oil, olive oil, cottonseed oil, sesame oil, soybean oil and other types. On the one hand, my country, as a major cotton-producing country, has abundant cottonseed oil reserves. On the other hand, cottonseed oil contains gossypol and residual pesticides and is gradually withdrawing from the edible oil market. Therefore, the development of cottonseed oil-based polyurethane is of great significance. However, the existing cottonseed oil-based polyurethane production process is complicated, the resulting product has a high viscosity, is difficult to control and scale up production, and the performance of the resulting polyurethane coating needs to be improved. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a cottonseed oil-based polyurethane coating based on microfluidic field technology and a preparation method and application thereof in view of the deficiencies in the prior art.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] The invention discloses a method for preparing a cottonseed oil-based polyurethane coating based on microfluidic field technology, comprising the following steps:

[0007] (1) mixing epoxidized cottonseed oil, an initiator, and a first solvent to obtain a first mixed solution; mixing isocyanate with a second solvent to obtain a second mixed solution; pumping the first mixed solution and the second mixed solution into a microfluidic reactor of a microfluidic reactor device to perform polymerization reaction, and collecting the effluent to obtain a cottonseed oil-based polyurethane prepolymer;

[0008] (2) Mixing and grinding the blending agent, solid pigment and titanate coupling agent, and then sequentially adding olefin monomer, polymerization inhibitor and light stabilizer, stirring evenly to obtain a color paste system;

[0009] (3) The cottonseed oil-based polyurethane prepolymer obtained in step (1) is mixed with the color paste system obtained in step (2) to obtain a cottonseed oil-based polyurethane coating based on microfluidic field technology.

[0010] In some embodiments, in step (1), the initiator is any one of dibutyltin dilaurate and stannous octoate or a combination of two thereof; and / or, the first solvent is any one of butyl acetate, toluene, xylene and ethyl acetate or a combination thereof; and / or, the isocyanate is any one of toluene-2,4-diisocyanate, 4,4'-methylenebis(phenyl isocyanate) and hexamethylene diisocyanate or a combination thereof; and / or, the second solvent is any one of butyl acetate, toluene, xylene and ethyl acetate or a combination thereof; and / or, during the polymerization reaction, the mass ratio of the epoxidized cottonseed oil to the initiator and isocyanate is (30-55): (0.4-2.0): (30-60); and / or, the polymerization reaction has a reaction temperature of 50°C to 80°C; and / or, the polymerization reaction in the microfluidic field reactor has a reaction residence time of 5.0 min to 30.0 min.

[0011] In some embodiments, preferably, in step (1), the initiator is dibutyltin dilaurate.

[0012] In some embodiments, preferably, in step (1), the first solvent is butyl acetate.

[0013] In some embodiments, preferably, in step (1), the isocyanate is toluene-2,4-diisocyanate.

[0014] In some embodiments, preferably, in step (1), the second solvent is butyl acetate.

[0015] There are no special requirements for the dosage of the first solvent and the second solvent, and the raw materials can be dissolved or dispersed evenly; there are no special requirements for the flow rate of the first mixed liquid pumped into the microfluidic reactor of the microfluidic reactor, and the flow rate of the second mixed liquid pumped into the microfluidic reactor of the microfluidic reactor, and it is ensured that during the polymerization reaction, the mass ratio of the epoxidized cottonseed oil to the initiator and isocyanate is within the range of (30-55): (0.4-2.0): (30-60).

[0016] In some embodiments, preferably, in step (1), during the polymerization reaction, the mass ratio of the epoxidized cottonseed oil to the initiator and the isocyanate is (35-55): (0.4-1.0): (40-50).

[0017] In some embodiments, it is further preferred that in step (1), during the polymerization reaction, the mass ratio of the epoxidized cottonseed oil to the initiator and the isocyanate is 35:0.4:45, 50:1.0:40, 40:0.6:45, 35:0.4:50 or 45:0.8:40.

[0018] In some embodiments, preferably, in step (1), the polymerization reaction has a reaction temperature of 50°C to 70°C, more preferably 60°C.

[0019] In some embodiments, preferably, in step (1), the polymerization reaction in the microfluidic field reactor has a reaction residence time of 5.0 min to 20.0 min, and more preferably 5.0 min to 10.0 min.

[0020] In some embodiments, in step (2), the blending agent is any one or a combination of glycerol, diethylene glycol, sorbitol and pentaerythritol; and / or, the solid pigment is any one or a combination of lithopone, titanium dioxide, red iron oxide, medium chrome yellow, phthalocyanine green, zinc oxide, ultramarine and toluidine red; and / or, the titanate coupling agent is titanate coupling agent YB-201; and / or, the olefin monomer is any one or a combination of styrene, methyl methacrylate, acrylonitrile and methacrylic acid; and / or, the polymerization inhibitor is hydroquinone; and / or, the light stabilizer is any one or a combination of 2-hydroxy-4-n-octyloxybenzophenone, antioxidant tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester and 2-hydroxy-4-hexyloxybenzophenone.

[0021] In some embodiments, preferably, in step (2), the conditioning agent is diethylene glycol or sorbitol.

[0022] In some embodiments, preferably, in step (2), the solid pigment is any one or a combination of titanium dioxide, medium chrome yellow, phthalocyanine green and toluidine red.

[0023] In some embodiments, preferably, in step (2), the vinyl monomer is methyl methacrylate.

[0024] In some embodiments, preferably, in step (2), the light stabilizer is 2-hydroxy-4-n-octyloxybenzophenone.

[0025] In some embodiments, in step (2), in the color paste system, by mass percentage, the amount of the blending agent is 10% to 25%, the amount of the solid pigment is 30% to 50%, the amount of the titanate coupling agent is 0.5% to 2.0%, the amount of the olefin monomer is 30% to 50%, the amount of the inhibitor is 0.1% to 1.5%, and the amount of the light stabilizer is 0.1% to 1.5%.

[0026] In some embodiments, preferably, in step (2), in the color paste system, by mass percentage, the amount of the blending agent is 15% to 20%, the amount of the solid pigment is 35% to 40%, the amount of the titanate coupling agent is 0.5% to 1.0%, the amount of the olefin monomer is 40% to 45%, the amount of the inhibitor is 0.2% to 0.5%, and the amount of the light stabilizer is 0.2% to 0.5%.

[0027] In some embodiments, it is further preferred that in step (2), in the color paste system, by mass percentage, the amount of the blending agent is 17%, the amount of the solid pigment is 38% to 40%, the amount of the titanate coupling agent is 0.8%, the amount of the olefin monomer is 41% to 43%, the amount of the inhibitor is 0.4%, and the amount of the light stabilizer is 0.4%.

[0028] In some embodiments, in step (2), the color paste system also includes a solid filler.

[0029] In some embodiments, in step (2), when the color paste system also includes a solid filler, the blending agent and solid pigment, solid filler, and titanate coupling agent are mixed and ground, and then olefin monomers, inhibitors, and light stabilizers are added in sequence and stirred evenly to obtain a color paste system.

[0030] In some embodiments, in step (2), the blending agent is any one or a combination of glycerol, diethylene glycol, sorbitol and pentaerythritol; and / or, the solid pigment is any one or a combination of lithopone, titanium dioxide, red iron oxide, medium chrome yellow, phthalocyanine green, zinc oxide, ultramarine and toluidine red; and / or, the titanate coupling agent is titanate coupling agent YB-201; and / or, the olefin monomer is any one or a combination of styrene, methyl methacrylate, acrylonitrile and methacrylic acid; and / or, the polymerization inhibitor is hydroquinone; and / or, the light stabilizer is any one or a combination of 2-hydroxy-4-n-octyloxybenzophenone, antioxidant tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester and 2-hydroxy-4-hexyloxybenzophenone.

[0031] In some embodiments, preferably, in step (2), the conditioning agent is diethylene glycol or sorbitol.

[0032] In some embodiments, preferably, in step (2), the solid pigment is any one or a combination of several of titanium dioxide, medium chrome yellow, phthalocyanine green and toluidine red.

[0033] In some embodiments, preferably, in step (2), the vinyl monomer is methyl methacrylate.

[0034] In some embodiments, preferably, in step (2), the light stabilizer is 2-hydroxy-4-n-octyloxybenzophenone.

[0035] In some embodiments, in step (2), when the color paste system further includes a solid filler, the solid filler is any one or a combination of green paste powder, bentonite, talc and barite.

[0036] In some embodiments, preferably, in step (2), when the color paste system further includes a solid filler, the solid filler is talcum powder.

[0037] In some embodiments, in step (2), when the color paste system also includes a solid filler, the amount of the color paste system, measured by mass percentage, is 10% to 25% of the blending agent, 30% to 45% of the solid pigment, 5% to 15% of the solid filler, 0.5% to 2.0% of the titanate coupling agent, 30% to 50% of the olefin monomer, 0.1% to 1.5% of the inhibitor, and 0.1% to 1.5% of the light stabilizer.

[0038] In some embodiments, preferably, in step (2), when the color paste system also includes a solid filler, the amount of the color paste system, measured by mass percentage, is 15% to 25% of the blending agent, 30% to 40% of the solid pigment, 5% to 15% of the solid filler, 0.5% to 1.5% of the titanate coupling agent, 30% to 45% of the olefin monomer, 0.3% to 0.5% of the inhibitor, and 0.3% to 0.5% of the light stabilizer.

[0039] In some embodiments, preferably, in step (2), when the color paste system also includes a solid filler, the amount of the color paste system, by mass percentage, is 17% to 21% of the blending agent, 33% to 36% of the solid pigment, 6% to 12% of the solid filler, 0.6% to 1.2% of the titanate coupling agent, 32% to 43% of the olefin monomer, 0.4% to 0.5% of the inhibitor, and 0.4% to 0.5% of the light stabilizer.

[0040] In some embodiments, in step (3), the mass ratio of the cottonseed oil-based polyurethane prepolymer to the color paste system is 1:(0.5-4.0).

[0041] In some embodiments, preferably, in step (3), the mass ratio of the cottonseed oil-based polyurethane prepolymer to the color paste system is 1:(0.5-2.0).

[0042] In some embodiments, further preferably, in step (3), the mass ratio of the cottonseed oil-based polyurethane prepolymer to the color paste system is 1:(0.8-1.5).

[0043] In some embodiments, in step (1), the microfluidic field reaction device includes a connecting pipe, a first feed pump, a second feed pump, a micromixer, a microfluidic field reactor and a receiver; wherein the first feed pump and the second feed pump are connected to the micromixer in parallel through pipes; and the micromixer, microfluidic field reactor and receiver are connected in series in sequence through pipes.

[0044] Wherein, the feed pump is Baoding Leifu Fluid Technology Co. Ltd, (TYD01-01-CE type).

[0045] Wherein, the micro mixer is a "Y"-shaped micro mixer or a "T"-shaped micro mixer with an inner diameter of 0.6 mm.

[0046] The microfluidic field reactor is a tubular reactor, the pipe material is perfluoroalkoxyalkane (PFA) or polytetrafluoroethylene, the inner diameter of the pipe is 0.5 mm to 1.0 mm, the length is 5 m to 20 m, and the volume is 1 mL to 15.7 mL.

[0047] Among them, preferably, the microfluidic field reactor is a tubular reactor, the pipe material is perfluoroalkoxyalkane (PFA) or polytetrafluoroethylene, the inner diameter of the pipe is 0.6 mm, and the volume is 2 mL or 4 mL.

[0048] The cottonseed oil-based polyurethane coating based on microfluidic field technology prepared by the above preparation method is also within the protection scope of the present invention.

[0049] Specifically, when the cottonseed oil-based polyurethane coating is poured on a glass template, the tensile strength of the coating film on the glass template is greater than 13.0 MPa; and / or, when the cottonseed oil-based polyurethane coating is poured on a glass template, the elongation at break of the coating film on the glass template is greater than 390%; and / or, when the cottonseed oil-based polyurethane coating is sprayed on a steel plate, the time for defects to appear on the coating after the coating is placed in water is greater than 220 hours; and / or, when the cottonseed oil-based polyurethane coating is sprayed on a steel plate, the mass loss of the coating after the coating is placed in 10% hydrochloric acid for 24 hours is less than 5.0%; and / or, when the cottonseed oil-based polyurethane coating is sprayed on a steel plate, the hardness of the coating on the steel plate is 3H or 4H.

[0050] Specifically, preferably, when the cottonseed oil-based polyurethane coating is poured on a glass template, the tensile strength of the coating film on the glass template is greater than 13.2 MPa.

[0051] Specifically, further preferably, when the cottonseed oil-based polyurethane coating is poured on a glass template, the tensile strength of the coating film on the glass template is 13.5 MPa to 16.0 MPa, and further preferably 13.5 MPa to 15.0 MPa.

[0052] Specifically, preferably, when the cottonseed oil-based polyurethane coating is poured on a glass template, the elongation at break of the coating film on the glass template is greater than 400%.

[0053] Specifically, further preferably, when the cottonseed oil-based polyurethane coating is poured on a glass template, the elongation at break of the coating film on the glass template is 405% to 600%, more preferably 410% to 500%, and most preferably 415% to 455%.

[0054] Specifically, preferably, when the cottonseed oil-based polyurethane coating is sprayed on a steel plate, the time for defects to appear on the coating when the coating is placed in water is greater than 240 hours.

[0055] Specifically, further preferably, when the cottonseed oil-based polyurethane coating is sprayed on a steel plate, the time for defects to appear on the coating when the coating is placed in water is 250 to 450 hours, and further preferably 250 to 350 hours.

[0056] Specifically, preferably, when the cottonseed oil-based polyurethane coating is sprayed on a steel plate, the mass loss of the coating is less than 4.5% after the coating is placed in 10% hydrochloric acid for 24 hours.

[0057] Specifically, further preferably, when the cottonseed oil-based polyurethane coating is sprayed on a steel plate, the mass loss of the coating after placing the coating in 10% hydrochloric acid for 24 hours is 0.5% to 4.0%, and further preferably 1.0% to 3.0%.

[0058] Specifically, preferably, when the cottonseed oil-based polyurethane coating is sprayed on a steel plate, the hardness of the coating on the steel plate is 4H.

[0059] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0060] (1) The present invention polymerizes epoxidized cottonseed oil and isocyanate under the action of an initiator through a microfluidic reaction device to obtain a cottonseed oil-based polyurethane prepolymer; the cottonseed oil-based polyurethane prepolymer is mixed with a color paste system to obtain a cottonseed oil-based polyurethane coating based on microfluidic technology. The present invention simplifies the polyurethane production process based on the high mass transfer and heat transfer efficiency of microreaction technology, and the viscosity of the obtained polyurethane prepolymer is controllable, which can be scaled up for production.

[0061] (2) The cottonseed oil-based polyurethane coating prepared by the present invention has excellent mechanical properties and chemical corrosion resistance, and is rich in color, has good decorative effect and is widely used, and has good economic and social benefits.

[0062] (3) Compared with Comparative Example 3, in Examples 1 to 5, the polymerization reaction time is 5 min to 10 min when the microfluidic reaction technology is used in the present invention, and the polymerization reaction time is 5 h when a conventional reactor is used. The microfluidic reaction technology improves the reaction efficiency by 30 to 60 times.

[0063] (4) Compared with Example 3, when Examples 1 to 5 are used in the present invention, the viscosity of the polyurethane prepolymer is 2300 mPa·s to 2500 mPa·s, which is much lower than the viscosity of the polyurethane prepolymer when a conventional reactor is used (Comparative Example 3, 3200 mPa·s). The use of microfluidic field reaction technology significantly reduces the viscosity by 22% to 28%.

[0064] (5) Compared with the conventional reaction technology of comparative example 3, the polyurethane coating prepared by the polyurethane prepolymer and the color paste system using the microfluidic reaction technology in Example 1 of the present invention has a tensile strength of 115% higher than that of the coating on the glass template, a breaking elongation of 155% higher than that of the coating on the glass template, a water resistance of 20% higher than that of the acid corrosion resistance of 81%, and a color uniformity higher than that of the conventional reactor. It can be seen that the microfluidic reaction technology is superior to the conventional reactor in terms of reaction time, product viscosity, mechanical properties, and color uniformity. The microchannel reaction device utilizes efficient mass transfer and heat transfer and a microchannel structure to achieve rapid reaction, stable and low viscosity, excellent network structure, good pigment dispersion, and low energy consumption; conventional reactors rely on mechanical stirring and natural convection, and have problems such as slow reaction, large viscosity fluctuations, poor mechanical properties, uneven color, and high energy consumption.

[0065] (6) Example 1 and Example 4 are compared with Comparative Example 1 and Comparative Example 2, that is, compared with cottonseed oil as raw material, the polyurethane coating prepared by using epoxy cottonseed oil as raw material in the present invention: the tensile strength of the coating on the glass template is increased by 54% to 67%, the elongation at break of the coating on the glass template is increased by 110% to 130%, the water resistance time is increased by 61% to 73%, the acid corrosion resistance is increased by 76% to 90%, and the hardness is also increased from 2H to 4H. In the microchannel reaction device, epoxy cottonseed oil has a high reaction activity of epoxy groups, a reaction rate constant greater than cottonseed oil, and a tighter cross-linking network (gel content is 15% to 25% higher), so that the tensile strength, elongation at break, hardness, water resistance and chemical corrosion resistance of the coating are all better than those of the polyurethane coating prepared by using cottonseed oil as raw material, and the application advantage is significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0067] Figure 1 This is a schematic diagram of the process of preparing cottonseed oil-based polyurethane prepolymer using a microfluidic field reaction device in an embodiment of the present invention.

[0068] Figure 2 This is a physical device diagram of the microfluidic field reaction device used in the embodiment of the present invention. DETAILED DESCRIPTION

[0069] The present invention can be better understood according to the following examples. However, it is easy for those skilled in the art to understand that the contents described in the examples are only used to illustrate the present invention, and should not and will not limit the present invention described in detail in the claims.

[0070] The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0071] The schematic diagram of the process of preparing cottonseed oil-based polyurethane prepolymer using a microfluidic reaction device in an embodiment of the present invention is as follows Figure 1 The physical device diagram of the microfluidic field reaction device used in the embodiment of the present invention is shown in FIG. Figure 2 The microfluidic reaction device comprises a connecting pipeline, a first feed pump, a second feed pump, a micro mixer, a microfluidic reactor and a receiver; wherein the first feed pump and the second feed pump are connected to the micro mixer in parallel through pipelines; and the micro mixer, the microfluidic reactor and the receiver are connected in series in sequence through pipelines.

[0072] Wherein, the feed pump is Baoding Leifu Fluid Technology Co. Ltd, (TYD01-01-CE type).

[0073] Wherein, the micro mixer is a "Y"-shaped micro mixer with an inner diameter of 0.6 mm.

[0074] Wherein, the microfluidic field reactor is a tubular reactor, the pipe material is polytetrafluoroethylene, the inner diameter of the pipe is 0.6mm, the length is 7m or 14m, and the volume is 2mL or 4mL.

[0075] The epoxidized cottonseed oil is mixed with an initiator and a first solvent to obtain a first mixed liquid; the isocyanate is mixed with a second solvent to obtain a second mixed liquid; the first mixed liquid and the second mixed liquid are simultaneously pumped into a microfluidic reactor of a microfluidic reaction device through a first feed pump and a second feed pump respectively to carry out a polymerization reaction, and the effluent is collected to obtain a cottonseed oil-based polyurethane prepolymer.

[0076] Embodiment 1:

[0077] (1) Preparation of cottonseed oil-based polyurethane prepolymer

[0078] The specific raw materials and their amounts in component A are: 35 parts by mass of epoxidized cottonseed oil (epoxy value 6.2%), 0.4 parts by mass of dibutyltin dilaurate, 45 parts by mass of toluene-2,4-diisocyanate, and 119.6 parts by mass of butyl acetate.

[0079] The above-mentioned mass parts of epoxidized cottonseed oil and the above-mentioned mass parts of dibutyltin dilaurate are dissolved in 64.6 mass parts of butyl acetate to obtain a first mixed solution; the above-mentioned mass parts of toluene-2,4-diisocyanate are dissolved in 55 mass parts of butyl acetate to obtain a second mixed solution.

[0080] The first mixed solution and the second mixed solution were pumped into the microfluidic reaction device at a flow rate of 0.2 mL / min, respectively, and then mixed in a micromixer (Y-type) and polymerized in a microfluidic reactor (inner diameter 0.6 mm, length 14 m, volume 4 mL), the reaction temperature was 60°C, and the reaction residence time in the microfluidic reactor was 10.0 min. After the reaction was completed, the reaction solution was collected to obtain a cottonseed oil-based polyurethane prepolymer, and the viscosity thereof was measured to be 2300 mPa.s.

[0081] (2) Preparation of color paste system

[0082] The specific proportion (mass fraction) of component B is: 17.0% diethylene glycol, 33.0% titanium dioxide, 6.0% talc, 0.8% titanate coupling agent YB-201, 42.4% methyl methacrylate, 0.4% hydroquinone, and 0.4% 2-hydroxy-4-n-octyloxybenzophenone.

[0083] The above mass fractions of diethylene glycol, titanium dioxide, talc and titanate coupling agent YB-201 are mixed and ground, and then methyl methacrylate, hydroquinone and 2-hydroxy-4-n-octyloxybenzophenone are added in sequence and stirred evenly to obtain component B.

[0084] (3) Preparation of white cottonseed oil-based polyurethane coating

[0085] The cottonseed oil-based polyurethane prepolymer obtained in step (1) and component B obtained in step (2) are mixed in a mass ratio of 1:1.2, an appropriate amount of butyl acetate is added, stirred evenly, allowed to stand for 30 minutes, poured on a glass template and sprayed on a steel plate at room temperature, and cured at a constant temperature of 30°C for 7 days.

[0086] Comparative Example 1:

[0087] (1) Preparation of cottonseed oil-based polyurethane prepolymer

[0088] The preparation method is the same as step (1) of Example 1, except that the epoxidized cottonseed oil is replaced by cottonseed oil, and finally a cottonseed oil-based polyurethane prepolymer is obtained, and its viscosity is measured to be 2200 mPa.s.

[0089] (2) Preparation of color paste system

[0090] The preparation method is the same as step (2) of Example 1.

[0091] (3) Preparation of white cottonseed oil-based polyurethane coating

[0092] The preparation method is the same as step (3) of Example 1, and a white cottonseed oil-based polyurethane coating is finally prepared.

[0093] Embodiment 2:

[0094] (1) Preparation of cottonseed oil-based polyurethane prepolymer

[0095] The specific raw materials and their amounts in component A are: 50 parts by mass of epoxidized cottonseed oil (epoxy value 6.2%), 1.0 parts by mass of stannous octoate, 40 parts by mass of toluene-2,4-diisocyanate, and 109 parts by mass of butyl acetate.

[0096] The above-mentioned mass parts of epoxidized cottonseed oil and the above-mentioned mass parts of stannous octoate are dissolved in 49 mass parts of butyl acetate to obtain a first mixed solution; the above-mentioned mass parts of toluene-2,4-diisocyanate are dissolved in 60 mass parts of butyl acetate to obtain a second mixed solution.

[0097] The first mixed solution and the second mixed solution were pumped into the microfluidic reaction device at a flow rate of 0.2 mL / min, respectively, and then mixed in a micromixer (Y-type) and polymerized in a microfluidic reactor (inner diameter 0.6 mm, length 14 m, volume 4 mL), the reaction temperature was 60°C, and the reaction residence time in the microfluidic reactor was 10.0 min. After the reaction was completed, the reaction liquid was collected to obtain a cottonseed oil-based polyurethane prepolymer, and the viscosity thereof was measured to be 2500 mPa.s.

[0098] (2) Preparation of color paste system

[0099] The specific proportion (mass fraction) of component B is: 17.0% diethylene glycol, 33.0% titanium dioxide, 6.0% talc, 0.8% titanate coupling agent YB-201, 42.4% methyl methacrylate, 0.4% hydroquinone, and 0.4% 2-hydroxy-4-n-octyloxybenzophenone.

[0100] The above mass fractions of diethylene glycol, titanium dioxide, talc and titanate coupling agent YB-201 are mixed and ground, and then methyl methacrylate, hydroquinone and 2-hydroxy-4-n-octyloxybenzophenone are added in sequence and stirred evenly to obtain component B.

[0101] (3) Preparation of white cottonseed oil-based polyurethane coating

[0102] The cottonseed oil-based polyurethane prepolymer obtained in step (1) and component B obtained in step (2) are mixed in a mass ratio of 1:1.5, an appropriate amount of butyl acetate is added, stirred evenly, allowed to stand for 30 minutes, poured onto a glass template and sprayed onto a steel plate at room temperature, and cured at a constant temperature of 30°C for 7 days.

[0103] Embodiment 3:

[0104] (1) Preparation of cottonseed oil-based polyurethane prepolymer

[0105] The specific raw materials and their amounts in component A are: 40 parts by mass of epoxidized cottonseed oil (epoxy value 6.2%), 0.6 parts by mass of dibutyltin dilaurate, 45 parts by mass of toluene-2,4-diisocyanate, and 114.4 parts by mass of butyl acetate.

[0106] The above-mentioned mass parts of epoxidized cottonseed oil and the above-mentioned mass parts of dibutyltin dilaurate are dissolved in 59.4 mass parts of butyl acetate to obtain a first mixed solution; the above-mentioned mass parts of toluene-2,4-diisocyanate are dissolved in 55 mass parts of butyl acetate to obtain a second mixed solution.

[0107] The first mixed liquid and the second mixed liquid were pumped into the microfluidic reaction device at a flow rate of 0.2 mL / min, respectively, and then mixed in a micromixer (Y-type) and polymerized in a microfluidic reactor (inner diameter 0.6 mm, length 7 m, volume 2 mL), the reaction temperature was 60°C, and the reaction residence time in the microfluidic reactor was 5.0 min. After the reaction was completed, the reaction liquid was collected to obtain a cottonseed oil-based polyurethane prepolymer, and the viscosity thereof was measured to be 2350 mPa.s.

[0108] (2) Preparation of color paste system

[0109] The specific proportion (mass fraction) of component B is: 17.8% sorbitol, 36% titanium dioxide, 12% talc, 1.2% titanate coupling agent YB-201, 32% methyl methacrylate, 0.5% hydroquinone, and 0.5% 2-hydroxy-4-n-octyloxybenzophenone.

[0110] Component B is obtained by mixing and grinding the above-mentioned mass fractions of sorbitol, titanium dioxide, talc and titanate coupling agent YB-201, and then sequentially adding methyl methacrylate, hydroquinone and 2-hydroxy-4-n-octyloxybenzophenone and stirring evenly.

[0111] (3) Preparation of white cottonseed oil-based polyurethane coating

[0112] The cottonseed oil-based polyurethane prepolymer obtained in step (1) and component B obtained in step (2) are mixed in a mass ratio of 1:0.8, an appropriate amount of butyl acetate is added, stirred evenly, allowed to stand for 30 minutes, poured onto a glass template and sprayed onto a steel plate at room temperature, and cured at a constant temperature of 30°C for 7 days.

[0113] Embodiment 4:

[0114] (1) Preparation of cottonseed oil-based polyurethane prepolymer

[0115] The specific raw materials and their amounts in component A are: 35 parts by mass of epoxidized cottonseed oil (epoxy value 6.2%), 0.4 parts by mass of dibutyltin dilaurate, 50 parts by mass of toluene-2,4-diisocyanate, and 114.6 parts by mass of butyl acetate.

[0116] The above-mentioned mass parts of epoxidized cottonseed oil and the above-mentioned mass parts of dibutyltin dilaurate are dissolved in 64.6 mass parts of butyl acetate to obtain a first mixed solution; the above-mentioned mass parts of toluene-2,4-diisocyanate are dissolved in 50 mass parts of butyl acetate to obtain a second mixed solution.

[0117] The first mixed liquid and the second mixed liquid were pumped into the microfluidic reaction device at a flow rate of 0.2 mL / min, respectively, and then mixed in a micromixer (Y-type) and polymerized in a microfluidic reactor (inner diameter 0.6 mm, length 14 m, volume 4 mL), the reaction temperature was 60°C, and the reaction residence time in the microfluidic reactor was 10.0 min. After the reaction was completed, the reaction liquid was collected to obtain a cottonseed oil-based polyurethane prepolymer, and the viscosity thereof was measured to be 2380 mPa.s.

[0118] (2) Preparation of color paste system

[0119] The specific proportion (mass fraction) of component B is: 20.4% diethylene glycol, 28% medium chrome yellow, 5% toluidine red, 6% talc, 0.6% titanate coupling agent YB-201, 39% methyl methacrylate, 0.5% hydroquinone, and 0.5% 2-hydroxy-4-n-octyloxybenzophenone.

[0120] The above mass fractions of diethylene glycol, medium chrome yellow, toluidine red, talcum powder and titanate coupling agent YB-201 are mixed and ground, and then methyl methacrylate, hydroquinone and 2-hydroxy-4-n-octyloxybenzophenone are added in sequence and stirred evenly to obtain component B.

[0121] (3) Preparation of yellow cottonseed oil-based polyurethane coating

[0122] The cottonseed oil-based polyurethane prepolymer obtained in step (1) and component B obtained in step (2) are mixed in a mass ratio of 1:1.2, an appropriate amount of butyl acetate is added, stirred evenly, allowed to stand for 30 minutes, poured on a glass template and sprayed on a steel plate at room temperature, and cured at a constant temperature of 30°C for 7 days.

[0123] Comparative Example 2:

[0124] (1) Preparation of cottonseed oil-based polyurethane prepolymer

[0125] The preparation method is the same as step (1) of Example 4, except that the epoxidized cottonseed oil is replaced by cottonseed oil, and finally a cottonseed oil-based polyurethane prepolymer is obtained, and its viscosity is measured to be 2100 mPa.s.

[0126] (2) Preparation of color paste system

[0127] The preparation method is the same as step (2) of Example 4.

[0128] (3) Preparation of yellow cottonseed oil-based polyurethane coating

[0129] The preparation method is the same as step (3) of Example 4, and finally a yellow cottonseed oil-based polyurethane coating is prepared.

[0130] Embodiment 5:

[0131] (1) Preparation of cottonseed oil-based polyurethane prepolymer

[0132] The specific raw materials and their amounts in component A are: 45 parts by mass of epoxidized cottonseed oil (epoxy value 6.2%), 0.8 parts by mass of dibutyltin dilaurate, 40 parts by mass of toluene-2,4-diisocyanate, and 114.2 parts by mass of butyl acetate.

[0133] The above-mentioned mass parts of epoxidized cottonseed oil and the above-mentioned mass parts of dibutyltin dilaurate are dissolved in 54.2 mass parts of butyl acetate to obtain a first mixed solution; the above-mentioned mass parts of toluene-2,4-diisocyanate are dissolved in 60 mass parts of butyl acetate to obtain a second mixed solution.

[0134] The first mixed solution and the second mixed solution were pumped into the microfluidic reaction device at a flow rate of 0.2 mL / min, respectively, and then mixed in a micromixer (Y-type) and polymerized in a microfluidic reactor (inner diameter 0.6 mm, length 14 m, volume 4 mL), the reaction temperature was 60°C, and the reaction residence time in the microfluidic reactor was 10.0 min. After the reaction was completed, the reaction liquid was collected to obtain a cottonseed oil-based polyurethane prepolymer, and the viscosity thereof was measured to be 2500 mPa.s.

[0135] (2) Preparation of color paste system

[0136] The specific proportion (mass fraction) of component B is: 17% diethylene glycol, 3.2% titanium dioxide, 5.2% medium chrome yellow, 30.6% phthalocyanine green, 0.8% titanate coupling agent YB-201, 42.4% methyl methacrylate, 0.4% hydroquinone, and 0.4% 2-hydroxy-4-n-octyloxybenzophenone.

[0137] The above mass fractions of diethylene glycol, titanium dioxide, medium chrome yellow, phthalocyanine green and titanate coupling agent YB-201 are mixed and ground, and then methyl methacrylate, hydroquinone and 2-hydroxy-4-n-octyloxybenzophenone are added in sequence and stirred evenly to obtain component B.

[0138] (3) Preparation of bright green cottonseed oil-based polyurethane coating

[0139] The cottonseed oil-based polyurethane prepolymer obtained in step (1) and component B obtained in step (2) are mixed in a mass ratio of 1:1.2, an appropriate amount of butyl acetate is added, stirred evenly, allowed to stand for 30 minutes, poured on a glass template and sprayed on a steel plate at room temperature, and cured at a constant temperature of 30°C for 7 days.

[0140] Comparative Example 3: Comparative Example of Example 1

[0141] (1) Preparation of cottonseed oil-based polyurethane prepolymer

[0142] The specific raw materials and their amounts in component A are: 35 parts by mass of epoxidized cottonseed oil (epoxy value 6.2%), 0.4 parts by mass of dibutyltin dilaurate, 45 parts by mass of toluene-2,4-diisocyanate, and 119.6 parts by mass of butyl acetate.

[0143] The above-mentioned mass parts of epoxidized cottonseed oil and the above-mentioned mass parts of dibutyltin dilaurate are dissolved in 64.6 mass parts of butyl acetate to obtain a first mixed solution; the above-mentioned mass parts of toluene-2,4-diisocyanate are dissolved in 55 mass parts of butyl acetate to obtain a second mixed solution.

[0144] The first mixed solution was stirred at 300 rpm to mix thoroughly, and then the second mixed solution was added dropwise to the first mixed solution, and the dropping speed was controlled to be 1.0 mL / min. At the same time, the reaction temperature was maintained at 60°C by condensed water. The entire reaction process lasted for 5 hours, and stirring was continued during the reaction to ensure uniform reaction. After the reaction was completed, the obtained product was a cottonseed oil-based polyurethane prepolymer, and its viscosity was measured to be 3200 mPa·s.

[0145] (2) Preparation of color paste system

[0146] The specific proportion (mass fraction) of component B is: 17.0% diethylene glycol, 33.0% titanium dioxide, 6.0% talc, 0.8% titanate coupling agent YB-201, 42.4% methyl methacrylate, 0.4% hydroquinone, and 0.4% 2-hydroxy-4-n-octyloxybenzophenone.

[0147] The above mass fractions of diethylene glycol, titanium dioxide, talc and titanate coupling agent YB-201 are mixed and ground, and then methyl methacrylate, hydroquinone and 2-hydroxy-4-n-octyloxybenzophenone are added in sequence and stirred evenly to obtain component B.

[0148] (3) Preparation of white cottonseed oil-based polyurethane coating

[0149] The cottonseed oil-based polyurethane prepolymer obtained in step (1) and component B obtained in step (2) are mixed in a mass ratio of 1:1.2, an appropriate amount of butyl acetate is added, stirred evenly, allowed to stand for 30 minutes, poured on a glass template and sprayed on a steel plate at room temperature, and cured at a constant temperature of 30°C for 7 days.

[0150] Embodiment 6:

[0151] The cottonseed oil-based polyurethane coatings prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were tested for coating surface drying time (finger touch method), tensile strength (coating tensile test), elongation at break (coating tensile test), coating gloss (gloss meter method), coating hardness (pencil hardness test), water resistance test (put the coating in water to count the time when defects appear in the coating), acid corrosion resistance (put the coating in 10% hydrochloric acid for 24 hours and calculate the mass loss of the coating), color difference test method (use a colorimeter to quantitatively measure the color uniformity of the polyurethane coating) and other parameters. The specific results are shown in Tables 1 and 2.

[0152] Table 1

[0153]

[0154]

[0155] Table 2

[0156] Color difference ΔE Color difference ΔE Example 1 1.2 Example 5 1.2 Example 2 1.3 Comparative Example 1 1.4 Example 3 0.9 Comparative Example 2 1.3 Example 4 1.1 Comparative Example 3 3.8

[0157] Experimental conclusion 1: Compared with comparative example 3, embodiments 1 to 5 have the following characteristics: (1) When the microfluidic reaction technology is used, the polymerization reaction time is 5 min to 10 min, while when a conventional reactor is used, the polymerization reaction time is 5 h. The reaction efficiency is increased by 30 to 60 times by the microfluidic reaction technology; (2) When the microfluidic reaction technology is used, the viscosity of the polyurethane prepolymer is 2300 mPa·s to 2500 mPa·s, which is much lower than the viscosity of the polyurethane prepolymer when a conventional reactor is used (Comparative example 3, 3200 mPa·s). The microfluidic reaction technology significantly reduces the viscosity by 22% to 28%.

[0158] Compared with the conventional reaction technology of Comparative Example 3, Example 1 adopts microfluidic field reaction technology to prepare the polyurethane coating prepared from the polyurethane prepolymer and the color paste system. The tensile strength of the coating film on the glass template is increased by 115%, the elongation at break of the coating film on the glass template is increased by 155%, the water resistance is increased by 20%, the acid corrosion resistance is increased by 81%, and the color uniformity is improved.

[0159] It can be seen that the microfluidic reaction technology is superior to conventional reactors in terms of reaction time, product viscosity, mechanical properties, and color uniformity. The microchannel reaction device uses efficient mass transfer and heat transfer and microchannel structure to achieve rapid reaction, stable and low viscosity, excellent network structure, good pigment dispersion, and low energy consumption; conventional reactors rely on mechanical stirring and natural convection, and have problems such as slow reaction, large viscosity fluctuations, poor mechanical properties, uneven color, and high energy consumption.

[0160] Experimental conclusion 2: Example 1 and Example 4 are compared with Comparative Example 1 and Comparative Example 2, that is, compared with cottonseed oil as raw material, the polyurethane coating prepared by using epoxy cottonseed oil as raw material: the tensile strength of the coating on the glass template is increased by 54% to 67%, the elongation at break of the coating on the glass template is increased by 110% to 130%, the water resistance time is increased by 61% to 73%, the acid corrosion resistance is increased by 76% to 90%, and the hardness is also increased from 2H to 4H. In the microchannel reaction device, epoxy cottonseed oil has high reaction activity of epoxy groups, a reaction rate constant greater than cottonseed oil, and a tighter cross-linked network (gel content is 15% to 25% higher), so that the tensile strength, elongation at break, hardness, water resistance and chemical corrosion resistance of the coating are all better than those of the polyurethane coating prepared by using cottonseed oil as raw material, and the application advantage is significant.

[0161] The present invention provides a cottonseed oil-based polyurethane coating based on microfluidic field technology and its preparation method and application ideas and methods. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A method for preparing a cottonseed oil-based polyurethane coating based on microfluidic field technology, characterized in that: The steps include: (1) mixing epoxidized cottonseed oil, an initiator, and a first solvent to obtain a first mixed solution; mixing isocyanate with a second solvent to obtain a second mixed solution; pumping the first mixed solution and the second mixed solution into a microfluidic reactor of a microfluidic reactor device to perform polymerization reaction, and collecting the effluent to obtain a cottonseed oil-based polyurethane prepolymer; (2) Mixing and grinding the blending agent, solid pigment and titanate coupling agent, and then sequentially adding olefin monomer, polymerization inhibitor and light stabilizer, stirring evenly to obtain a color paste system; (3) The cottonseed oil-based polyurethane prepolymer obtained in step (1) is mixed with the color paste system obtained in step (2) to obtain a cottonseed oil-based polyurethane coating based on microfluidic field technology.

2. The preparation method according to claim 1, characterized in that: In step (1), the initiator is any one of dibutyltin dilaurate and stannous octoate or a combination of two thereof; and / or, the first solvent is any one of butyl acetate, toluene, xylene and ethyl acetate or a combination thereof; and / or, the isocyanate is any one of toluene-2,4-diisocyanate, 4,4'-methylenebis(phenyl isocyanate) and hexamethylene diisocyanate or a combination thereof; and / or, the second solvent is any one of butyl acetate, toluene, xylene and ethyl acetate or a combination thereof; and / or, during the polymerization reaction, the mass ratio of the epoxidized cottonseed oil to the initiator and the isocyanate is (30-55): (0.4-2.0): (30-60); and / or, the polymerization reaction has a reaction temperature of 50°C to 80°C; and / or, the polymerization reaction in the microfluidic field reactor has a reaction residence time of 5.0 min to 30.0 min.

3. The preparation method according to claim 1, characterized in that: In step (2), the color paste system also includes a solid filler; and / or, When the color paste system also includes solid fillers, the blending agent, solid pigment, solid filler and titanate coupling agent are mixed and ground, and then olefin monomers, polymerization inhibitors and light stabilizers are added in sequence and stirred evenly to obtain the color paste system.

4. The preparation method according to claim 1 or claim 3, characterized in that: In step (2), the blending agent is any one or a combination of glycerol, diethylene glycol, sorbitol and pentaerythritol; and / or the solid pigment is any one or a combination of lithopone, titanium dioxide, red iron oxide, medium chrome yellow, phthalocyanine green, zinc oxide, ultramarine and toluidine red; and / or the titanate coupling agent is titanate coupling agent YB-201; and / or the olefin monomer is any one or a combination of styrene, methyl methacrylate, acrylonitrile and methacrylic acid; and / or the polymerization inhibitor is hydroquinone; and / or the light stabilizer is any one or a combination of 2-hydroxy-4-n-octyloxybenzophenone, antioxidant tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester and 2-hydroxy-4-hexyloxybenzophenone.

5. The preparation method according to claim 1, characterized in that: In the color paste system, by mass percentage, the amount of the blending agent is 10% to 25%, the amount of the solid pigment is 30% to 50%, the amount of the titanate coupling agent is 0.5% to 2.0%, the amount of the olefin monomer is 30% to 50%, the amount of the inhibitor is 0.1% to 1.5%, and the amount of the light stabilizer is 0.1% to 1.5%.

6. The preparation method according to claim 3, characterized in that: When the color paste system also includes solid fillers, the solid fillers are any one or a combination of blue paste powder, bentonite, talc and barite; and / or, when the color paste system also includes solid fillers, in the color paste system, by mass percentage, the amount of the blending agent is 10% to 25%, the amount of the solid pigment is 30% to 45%, the amount of the solid filler is 5% to 15%, the amount of the titanate coupling agent is 0.5% to 2.0%, the amount of the olefin monomer is 30% to 50%, the amount of the inhibitor is 0.1% to 1.5%, and the amount of the light stabilizer is 0.1% to 1.5%.

7. The preparation method according to claim 1, characterized in that: In step (3), the mass ratio of the cottonseed oil-based polyurethane prepolymer to the color paste system is 1:(0.5-4.0).

8. The preparation method according to claim 1, characterized in that: In step (1), the microfluidic field reaction device includes a connecting pipe, a first feed pump, a second feed pump, a micromixer, a microfluidic field reactor and a receiver; wherein the first feed pump and the second feed pump are connected to the micromixer in parallel through a pipe; and the micromixer, the microfluidic field reactor and the receiver are connected in series in sequence through a pipe.

9. Cottonseed oil-based polyurethane coating based on microfluidic field technology prepared by the preparation method according to any one of claims 1 to 8.

10. The cottonseed oil-based polyurethane coating based on microfluidic field technology according to claim 9, characterized in that: When the cottonseed oil-based polyurethane coating is poured on a glass template, the tensile strength of the coating on the glass template is greater than 13.0 MPa; and / or, when the cottonseed oil-based polyurethane coating is poured on a glass template, the elongation at break of the coating on the glass template is greater than 390%; and / or, when the cottonseed oil-based polyurethane coating is sprayed on a steel plate, the time for defects to appear on the coating after the coating is placed in water is greater than 220 hours; and / or, when the cottonseed oil-based polyurethane coating is sprayed on a steel plate, the mass loss of the coating after the coating is placed in 10% hydrochloric acid for 24 hours is less than 5.0%; and / or, when the cottonseed oil-based polyurethane coating is sprayed on a steel plate, the hardness of the coating on the steel plate is 3H or 4H.

Images