An ultra-flat acrylic resin composition, a preparation method thereof, and an application thereof to an automobile

Abstract

The application belongs to the technical field of acrylic resin compositions, and specifically provides an ultra-leveling acrylic resin composition, a preparation method thereof and application thereof on automobiles. The ultra-leveling acrylic resin composition is prepared from the following raw materials: an acrylic ester, styrene, modified fibers, pretreated nano-silica, wherein the modified fibers are obtained by using fluorinated polyurethane and polyacrylonitrile as a matrix and then through activation treatment, and the pretreated nano-silica is nano-silica treated by amino silane. The ultra-leveling acrylic resin composition prepared by the application has the advantages of good leveling property, wear resistance and corrosion resistance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of acrylic resin composition, in particular relates to a super leveling acrylic resin composition, a preparation method thereof and application thereof on automobiles. BACKGROUND

[0002] During the use of automobiles, components such as chassis and fenders are exposed to harsh environments for a long time, and are subjected to impacts from gravel, water erosion, chemical corrosion and complex road conditions, which can easily cause coating damage, metal corrosion and other problems, seriously affecting the safety and service life of the vehicle. Therefore, high-performance protective coating materials are the key to ensuring the reliability of the chassis. Resin compositions are widely concerned in the field of automobile component protection due to their flexible performance adjustment through component design.

[0003] Currently, various resin composition coatings have been widely used in the protection of automobile components. Epoxy resin compositions can form a dense base layer on the surface of the substrate due to their high strength and adhesion; acrylic resin compositions can further enhance the resistance of the coating to ultraviolet light and acid rain due to their excellent weather resistance and good film-forming properties, and the combination of the two can provide basic protection for the substrate. In addition, the high wear resistance and good elasticity of polyurethane resin compositions can also alleviate the damage caused by gravel impact and vibration to automobile components, while improving the durability of the coating.

[0004] However, existing resin compositions still have significant defects in actual application. In terms of leveling, the structure of automobile components is complex, and resin coatings are difficult to spread uniformly after spraying, often causing defects such as orange peel and shrinkage, affecting the appearance and protective performance of the coating. In terms of friction resistance, automobile components are often subjected to external friction or self-vibration wear during vehicle operation, and existing resin coatings lack hardness and toughness, which can easily cause wear and peeling, thereby shortening the protective period of the coating. In terms of corrosion resistance, resin coatings are difficult to resist corrosion for a long time in the face of salt in road deicing agents and acidic substances in industrial waste gas, and once the coating is damaged, the substrate of the automobile component will be quickly corroded, threatening the safety of the vehicle structure. Therefore, it is urgent to develop resin compositions that are significantly optimized in leveling, friction resistance and corrosion resistance to improve the protective performance of automobile components. SUMMARY

[0005] In order to further improve the leveling performance, wear resistance and corrosion resistance of acrylic resin compositions, the present application provides a super leveling acrylic resin composition, a preparation method thereof and application thereof on automobiles.

[0006] In a first aspect, the application provides an ultra-flat acrylic resin composition, which is prepared from the following raw materials: acrylic ester, styrene, modified fiber, and pretreated nano-silica; the modified fiber is obtained by activating a composite fiber matrix prepared by electrospinning fluorinated polyurethane and polyacrylonitrile; and the pretreated nano-silica is obtained by mixing and reacting nano-silica and amino silane.

[0007] Further, the preparation method of the fluorinated polyurethane comprises the following steps: mixing aromatic isocyanate, aliphatic isocyanate, and polyether polyol, adding a catalyst to perform polymerization reaction, then adding perfluoroalkyl alcohol and chain extender to perform chain extension reaction, and finally solidifying, drying, crushing, and obtaining the fluorinated polyurethane.

[0008] Further, the mass ratio of the fluorinated polyurethane to the polyacrylonitrile is 1:(2.5-4).

[0009] Further, the process parameters of the electrospinning are as follows: receiving distance 18-22 cm, and electric field voltage 28-33 kV.

[0010] Further, the average length of the composite fiber matrix is 30-60 μm.

[0011] Further, the activation treatment comprises the following steps: immersing the composite fiber matrix in a sodium thiocyanate aqueous solution for impregnation, then mixing with lye, and reacting at 70-90 ℃ for 0.5-1 h.

[0012] Further, the molar ratio of the aromatic isocyanate to the aliphatic isocyanate is 1:(1.5-3).

[0013] And / or, the molar ratio of the perfluoroalkyl alcohol to the chain extender is 1:(1-4).

[0014] Further, the chain extender is one of ethylenediamine, 1,4-butanediol, and diethyltoluene diamine.

[0015] In a second aspect, the application provides a preparation method of the ultra-flat acrylic resin composition, which comprises the following steps: mixing acrylic ester and styrene, heating to 60-70 ℃, reacting for 3-5 h, filtering, then adding modified fiber and pretreated nano-silica, and ultrasonically obtaining the ultra-flat acrylic resin composition.

[0016] In a third aspect, the application provides an application of the above ultra-flat acrylic resin composition on a car, wherein the ultra-flat resin composition is sprayed on a car part, solidified and dried to form a protective film layer; and the car part comprises a mudguard, a chassis, and a pedal.

[0017] Compared with the prior art, the application has the following beneficial effects:

[0018] 1、The modified fiber is added with fluorinated polyurethane, under the action of the low surface tension of the fluorinated polyurethane, the modified fiber has the ability to migrate to the surface of the coating, thereby reducing the surface tension of the coating surface, promoting the uniform spreading of the molecules, and eliminating the surface defects in the construction process; at the same time, part of the modified fiber is enriched on the surface, which improves the surface hardness of the coating, and further enhances the impact resistance and wear resistance of the coating.

[0019] 2, The fiber is soaked with an aqueous solution of sodium thiocyanate to swell and dissolve part of the polyacrylonitrile on the surface of the fiber, increase the exposure of fluorinated polyurethane, and improve the migration ability of the modified fiber to the surface; at the same time, it also improves the surface roughness of the fiber, increases the adhesion between the fiber and the coating matrix, avoids phase separation, and further improves the wear resistance of the coating.

[0020] 3, The polyacrylonitrile in the fiber is treated with carboxyl, and part of the pretreated nano-silicon dioxide is combined with the carboxylated polyacrylonitrile during the curing process of the coating. The pretreated silicon dioxide tends to be enriched near the modified fiber, thereby increasing the content of silicon dioxide on the surface of the coating, further improving the compactness of the coating surface, and improving the wear resistance and corrosion resistance of the coating. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Contact angle test data of the coating film prepared from the super-flat acrylic resin composition of the present application Examples 1-3 and Control Examples 1-2. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part 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 are within the scope of protection of the present application.

[0023] After a large number of experimental researches, the present application provides a preparation method of a super-flat acrylic resin composition, comprising the following steps: mixing acrylate and styrene, stirring at a rate of 80-120 r / min for 10-20 min, then adding an initiator, heating to 60-70℃, and stirring at a rate of 100-150 r / min for 3-5 h. After the reaction is completed, cool to room temperature, filter, then add a leveling agent, a defoaming agent, a plasticizer, a modified fiber, and pretreated nano-silicon dioxide, and ultrasonic at a frequency of 20-40 Hz for 15-30 min to obtain a super-flat acrylic resin composition.

[0024] Further, the preparation method of the modified fiber comprises the following steps: mixing fluorinated polyurethane, polyacrylonitrile and N,N-dimethylformamide to obtain a spinning solution; taking the spinning solution to perform electrostatic spinning, drying, cutting and crushing to obtain a composite fiber matrix; taking the composite fiber matrix to perform activation treatment, filtering and drying to obtain the modified fiber.

[0025] Further, the pretreated nanosilica is prepared by mixing and reacting nanosilica and aminosilane.

[0026] In some specific embodiments, the aminosilane can be 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl) 3-aminopropyltrimethoxysilane or anilinomethyltriethoxysilane. In general, when the aminosilane is 3-aminopropyltrimethoxysilane or 3-aminopropyltriethoxysilane, better experimental results can be obtained.

[0027] Further, the preparation method of the fluorinated polyurethane comprises the following steps: mixing aromatic isocyanate, aliphatic isocyanate and polyether polyol, adding a catalyst to perform polymerization reaction, then adding perfluoroalkyl alcohol and a chain extender to perform chain extension reaction, and curing, drying, crushing to obtain the fluorinated polyurethane.

[0028] Further, the process parameters of the electrostatic spinning are as follows: a receiving distance of 18-22 cm, a reciprocating moving speed of the sliding table of 80-110 cm / min, an electric field voltage of 28-33 kV and a rotating speed of the roller of 45-55 rpm.

[0029] In some specific embodiments, the process parameters of the electrostatic spinning can be as follows: a receiving distance of 18 cm, 19 cm, 20 cm, 21 cm or 22 cm, a reciprocating moving speed of the sliding table of 80 cm / min, 85 cm / min, 90 cm / min, 95 cm / min, 100 cm / min, 105 cm / min or 110 cm / min, an electric field voltage of 28 kV, 29 kV, 30 kV, 31 kV, 32 kV or 33 kV, and a rotating speed of the roller of 45 rpm, 46 rpm, 47 rpm, 48 rpm, 49 rpm, 50 rpm, 51 rpm, 52 rpm, 53 rpm, 54 rpm or 55 rpm. In general, when the process parameters of the electrostatic spinning are as follows: a receiving distance of 20 cm, a reciprocating moving speed of the sliding table of 100 cm / min, an electric field voltage of 30 kV and a rotating speed of the roller of 50 rpm, better experimental results can be obtained.

[0030] Further, the average length of the composite fiber matrix is 30-60 μm.

[0031] In some embodiments, the average length of the composite fiber substrate can be 30 pm, 35 pm, 40 pm, 45 pm, 50 pm, 55 pm, 60 pm. In general, the average length of the composite fiber substrate is 40 pm, the experimental results are better.

[0032] Further, the activation treatment is to immerse the composite fiber substrate in a sodium thiocyanate aqueous solution with a mass percentage concentration of 45%-55%, then mix with lye, and react at 70-90°C for 0.5-1h.

[0033] In some embodiments, the mass percentage concentration of the sodium thiocyanate aqueous solution can be 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%. In general, the mass percentage concentration of the sodium thiocyanate aqueous solution is 51%, and better experimental results can be obtained.

[0034] Further, the mass ratio of the fluorinated polyurethane to the polyacrylonitrile is 1:(2.5-4).

[0035] In some embodiments, the mass ratio of the fluorinated polyurethane to the polyacrylonitrile can be 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, 1:3, 1:3.1, 1:3.2, 1:3.3, 1:3.4, 1:3.5, 1:3.6, 1:3.7, 1:3.8, 1:3.9, 1:4. In general, the mass ratio of the fluorinated polyurethane to the polyacrylonitrile is 1:3.7, and better experimental results can be obtained.

[0036] Further, the molar ratio of the aromatic isocyanate to the aliphatic isocyanate is 1:(1.5-3);

[0037] And / or, the molar ratio of the perfluoroalkyl alcohol to the chain extender is 1:(1-4).

[0038] In some embodiments, the molar ratio of the aromatic isocyanate to the aliphatic isocyanate can be 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, 1:3. In general, the molar ratio of the aromatic isocyanate to the aliphatic isocyanate is 1:2.5, and better experimental results can be obtained.

[0039] In some embodiments, the molar ratio of the perfluoroalkyl alcohol to the chain extender can be 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, 1:3, 1:3.2, 1:3.4, 1:3.6, 1:3.8, 1:4. In general, the molar ratio of the perfluoroalkyl alcohol to the chain extender is 1:2, better experimental results can be obtained.

[0040] Further, the chain extender is one of ethylenediamine, 1,4-butanediol and diethyl toluene diamine.

[0041] In some embodiments, in general, when the chain extender is 1,4-butanediol, better experimental results can be obtained.

[0042] Example 1

[0043] The preparation method of the super leveling acrylic resin composition of the present embodiment is as follows:

[0044] 10 g of glycidyl methacrylate, 35 g of methyl methacrylate, 20 g of butyl acrylate, 15 g of styrene, and 15 g of butyl acetate were weighed into a 250 mL flask, stirred at a rate of 80 r / min for 20 min, then 0.8 g of azobisisobutyronitrile was added, heated to 60°C, and stirred at a rate of 150 r / min for 3 h. After the reaction was completed, the product was cooled to room temperature, filtered, and the liquid component was retained. Then 0.3 g of leveling agent BYK-306, 0.1 g of defoaming agent BYK-052, 2.4 g of dioctyl phthalate, 1 g of modified fiber, and 6 g of pretreated nano-silica were added, and ultrasonic dispersion was performed under the condition of a frequency of 20 Hz for 30 min to obtain a super leveling acrylic resin composition.

[0045] The preparation method of the modified fiber of the present embodiment is as follows:

[0046] 1) 5.36 g of diphenylmethane diisocyanate and 11.91 g of isophorone diisocyanate were weighed into a four-necked flask, heated to 60°C under a nitrogen atmosphere, stirred for 30 min, then 42.50 g of polytetramethylene ether glycol (PTMEG-2000) was added, the stirring rate was controlled at 80 rpm, the temperature was again raised to 80°C, then 0.1 g of dibutyltin dilaurate was added, the reaction was carried out for 2 h, after the reaction was completed, the system temperature was lowered to 70°C, a mixture solution of 2.3 g of octafluoropentanol and 1.8 g of 1,4-butanediol was added at a rate of 0.8 g / min, and the reaction was continued for 1 h. After the reaction was completed, the product was poured into a polytetrafluoroethylene mold, the mold was placed in a vacuum oven, vacuum degassing was carried out at 100°C for 10 min, then curing and drying were carried out at 100°C for 16 h, and the product was crushed to obtain a fluorinated polyurethane.

[0047] 2) Take 2 g of fluorinated polyurethane, 7.4 g of polyacrylonitrile into a three-necked flask, add 95 g of N,N-dimethylformamide, stir at a rate of 100 rpm for 5 h to obtain a spinning solution; inject the spinning solution into a syringe for electrospinning, during the electrospinning process, the receiving distance is 20 cm, the reciprocating speed of the slide table is 100 cm / min, the voltage of the electric field is 30 kV, the rotating speed of the drum is 50 rpm, and after drying, cutting and crushing, a composite fiber matrix with an average length of 40 μm is obtained;

[0048] 3) Take 10 g of the composite fiber matrix and immerse it in 30 g of a 51% mass percentage concentration sodium thiocyanate aqueous solution, soak for 30 min, filter, dry, and then add it into a three-necked flask, add 50 g of an 8% mass percentage concentration sodium hydroxide aqueous solution, heat to 70℃, react for 1 h, filter, dry, and obtain the modified fiber.

[0049] The preparation method of the pretreated nanometer silicon dioxide in this embodiment is as follows: take 5 g of nanometer silicon dioxide, add it into a 250 mL three-necked flask, add 70 mL of anhydrous toluene to the three-necked flask, place the three-necked flask in an ultrasonic cleaner, ultrasonic dispersion for 15 min, then place the three-necked flask in an oil bath, add 3.8 g of 3-aminopropyltrimethoxysilane to the three-necked flask, heat to 110℃, stir for 24 h, centrifugal separation, washing, and drying to obtain the pretreated nanometer silicon dioxide.

[0050] Example 2

[0051] The preparation method of the super leveling acrylic resin composition in this embodiment is as follows:

[0052] Take 10 g of glycidyl methacrylate, 30 g of methyl methacrylate, 15 g of butyl acrylate, 25 g of styrene, and 15 g of butyl acetate into a 250 mL flask, stir at a rate of 120 r / min for 10 min, then add 0.5 g of azobisisobutyronitrile, heat to 70℃, and stir at a rate of 100 r / min for 5 h. After the reaction is completed, cool the product to room temperature, filter, retain the liquid component, and then add 0.2 g of leveling agent EFKA 3777, 0.1 g of defoaming agent TEGO Airex 900, 2 g of tributyl citrate, 1.2 g of modified fiber, and 5 g of pretreated nanometer silicon dioxide, ultrasonic dispersion for 15 min under the condition of a frequency of 40 Hz, and obtain the super leveling acrylic resin composition.

[0053] The preparation method of the modified fiber in this embodiment is as follows:

[0054] 1) Weigh 5.36g of diphenylmethane diisocyanate and 11.91g of isophorone diisocyanate into a four-necked flask. Under a nitrogen atmosphere, heat to 65°C and stir for 30 min. Then add 42.50g of polypropylene glycol (PPG-2000) and control the stirring speed at 100 rpm. Heat again to 80°C and then add 0.05g of dibutyltin dilaurate. React for 3 h. After the reaction, lower the system temperature to 70°C and add a mixed solution of 2.3g of octafluoropentanol and 1.8g of 1,4-butanediol at a rate of 0.8g / min. Continue to react for 1 h. After the reaction, pour the product into a polytetrafluoroethylene mold and place the mold in a vacuum oven. Degas at 100°C for 10 min and then cure and dry at 100°C for 16 h. Crush to obtain fluorinated polyurethane.

[0055] 2) Weigh 2g of fluorinated polyurethane and 7.6g of polyacrylonitrile into a three-necked flask, add 95g of N,N-dimethylformamide, and stir at 100rpm for 5h to obtain a spinning solution; inject the spinning solution into a syringe for electrospinning. During electrospinning, the receiving distance is 20cm, the reciprocating speed of the slide is 100cm / min, the electric field voltage is 30kV, and the rotation speed of the roller is 50rpm. After drying, cutting and crushing, a composite fiber matrix with an average length of 40μm is obtained.

[0056] 3) Weigh 10g of composite fiber matrix and soak it in 30g of sodium thiocyanate aqueous solution with a mass percentage concentration of 51% for 40min. After filtration and drying, put it into a three-necked flask, add 50g of sodium hydroxide aqueous solution with a mass percentage concentration of 8%, heat to 90℃, react for 0.5h, filter, and dry to obtain modified fiber.

[0057] The preparation method of pretreated nano-silica in this embodiment is as follows: Weigh 5g of nano-silica and add it to a 250mL three-necked flask. Then add 70mL of anhydrous toluene to the three-necked flask. Place the three-necked flask in an ultrasonic cleaner and ultrasonically disperse for 15min. Then place the three-necked flask in an oil bath. Next, add 4g of 3-aminopropyltriethoxysilane to the three-necked flask, heat to 100℃, stir for 20h, centrifuge, wash, and dry to obtain pretreated nano-silica.

[0058] Example 3

[0059] The preparation method of the super-leveling acrylic resin composition in this embodiment is as follows:

[0060] Take 10 g of glycidyl methacrylate, 40 g of methyl methacrylate, 10 g of butyl acrylate, 20 g of styrene, 15 g of butyl acetate into a 250 mL flask, stir at a rate of 110 r / min for 15 min, then add 1 g of azobisisobutyronitrile, heat to 65℃, stir at a rate of 140 r / min for 3.5 h, after the reaction is completed, the product is cooled to room temperature, filtered, and the liquid component is retained, then 0.1 g of leveling agent BYK-306, 0.1 g of defoaming agent Di Gu 931, 2 g of dioctyl phthalate, 1.5 g of modified fiber, 6 g of pretreated nano-silicon dioxide are added, and ultrasonic dispersion is carried out under the condition of a frequency of 35 Hz for 28 min to obtain a super leveling acrylic resin composition.

[0061] The preparation method of the modified fiber of the present embodiment is as follows:

[0062] 1) Take 5.5 g of diphenylmethane diisocyanate and 11 g of isophorone diisocyanate into a four-necked flask, heat to 60℃ under a nitrogen atmosphere, stir for 30 min, then add 42 g of polytetramethylene ether glycol (PTMEG-2000), control the stirring rate at 80 rpm, reheat to 80℃, then add 0.1 g of dibutyltin dilaurate, react for 2 h, after the reaction is completed, the system temperature is lowered to 70℃, a mixture solution of 3 g of octafluoropentanol and 1,4-butanediol 1.5 g is added at a rate of 0.5 g / min, and the reaction is continued for 1 h. After the reaction is completed, the product is poured into a polytetrafluoroethylene mold, the mold is placed in a vacuum oven, vacuum degassing is carried out at 100℃ for 10 min, then curing and drying are carried out at 100℃ for 16 h, and the product is crushed to obtain a fluorinated polyurethane;

[0063] 2) Take 2 g of fluorinated polyurethane and 7.4 g of polyacrylonitrile into a three-necked flask, add 90 g of N,N-dimethylformamide, and stir at a rate of 100 rpm for 5 h to obtain a spinning solution; the spinning solution is injected into a syringe for electrospinning, and during the electrospinning process, the receiving distance is 20 cm, the reciprocating speed of the slide table is 100 cm / min, the voltage of the electric field is 30 kV, and the rotating speed of the drum is 50 rpm; after drying and cutting and crushing, a composite fiber matrix with an average length of 60 μm is obtained;

[0064] 3) Take 10 g of the composite fiber matrix and immerse it in 30 g of a 51% mass percentage concentration sodium thiocyanate aqueous solution, soak for 35 min, filter and dry, then add to a three-necked flask, add 50 g of a 8% mass percentage concentration sodium hydroxide aqueous solution, heat to 85℃, react for 50 min, filter and dry to obtain a modified fiber.

[0065] The preparation method of the pretreated nanometer silicon dioxide of the embodiment is as follows: 5 g of nanometer silicon dioxide is weighed and added into a 250 mL three-necked flask, 70 mL of anhydrous toluene is added into the three-necked flask, the three-necked flask is placed in an ultrasonic cleaner, and ultrasonic dispersion is performed for 15 min; then the three-necked flask is placed in an oil bath, 4.5 g of 3-aminopropyltrimethoxysilane is added into the three-necked flask, heating is performed to 110°C, and stirring is performed for 24 h; then centrifugal separation, washing, and drying are performed to obtain the pretreated nanometer silicon dioxide.

[0066] Control group 1

[0067] The preparation method of the super flat acrylic resin composition of the control group is as follows:

[0068] 10 g of glycidyl methacrylate, 35 g of methyl methacrylate, 20 g of butyl acrylate, 15 g of styrene, and 15 g of butyl acetate are weighed and put into a 250 mL flask, stirring is performed at a rate of 80 r / min for 20 min, 0.8 g of azobisisobutyronitrile is added, heating is performed to 60°C, and stirring is performed at a rate of 150 r / min for 3 h; after the reaction is completed, the product is cooled to room temperature, filtration is performed, the liquid component is reserved, 0.3 g of leveling agent BYK-306, 0.1 g of defoaming agent BYK-052, 2.4 g of dioctyl phthalate, 1 g of modified fiber, and 6 g of nanometer silicon dioxide are added, ultrasonic dispersion is performed for 30 min under the condition of a frequency of 20 Hz, and the super flat acrylic resin composition is obtained.

[0069] The preparation method of the modified fiber of the control group is as follows:

[0070] 1) 5.36 g of diphenylmethane diisocyanate and 11.91 g of isophorone diisocyanate are weighed and put into a four-necked flask, heating is performed to 60°C under a nitrogen atmosphere, and stirring is performed for 30 min; then 42.50 g of polytetramethylene ether glycol (PTMEG-2000) is added, the stirring rate is controlled to be 80 rpm, the temperature is increased to 80°C again, 0.1 g of dibutyltin dilaurate is added, reaction is performed for 2 h, after the reaction is completed, the system temperature is lowered to 70°C, a mixed solution of 2.3 g of octafluoropentanol and 1,4-butanediol 1.8 g is added at a rate of 0.8 g / min, and reaction is continuously performed for 1 h; after the reaction is completed, the product is poured into a polytetrafluoroethylene mold, the mold is placed in a vacuum oven, vacuum degassing is performed at 100°C for 10 min, and then curing and drying are performed at 100°C for 16 h; after that, the product is crushed to obtain the fluorinated polyurethane.

[0071] 2) Take 2 g of fluorinated polyurethane, 7.4 g of polyacrylonitrile into a three-necked flask, add 95 g of N,N-dimethylformamide, stir at a speed of 100 rpm for 5 h to obtain a spinning solution; inject the spinning solution into a syringe for electrospinning, during the electrospinning process, the receiving distance is 20 cm, the reciprocating speed of the slide table is 100 cm / min, the voltage of the electric field is 30 kV, the rotating speed of the drum is 50 rpm, after drying, cutting and crushing, a composite fiber matrix with an average length of 40 μm is obtained;

[0072] 3) Take 10 g of the composite fiber matrix and immerse it in 30 g of a 51% mass percentage concentration sodium thiocyanate aqueous solution for 30 min, filter and dry, then put it into a three-necked flask, add 50 g of an 8% mass percentage concentration sodium hydroxide aqueous solution, heat to 70℃, react for 1 h, filter and dry to obtain a modified fiber.

[0073] Control group 2

[0074] The preparation method of the super leveling acrylic resin composition of the control group is as follows:

[0075] Take 10 g of glycidyl methacrylate, 35 g of methyl methacrylate, 20 g of butyl acrylate, 15 g of styrene, and 15 g of butyl acetate into a 250 mL flask, stir at a speed of 80 r / min for 20 min, then add 0.8 g of azobisisobutyronitrile, heat to 60℃, stir at a speed of 150 r / min for 3 h, after the reaction is completed, cool the product to room temperature, filter, retain the liquid component, then add 0.3 g of leveling agent BYK-306, 0.1 g of defoaming agent BYK-052, 2.4 g of dioctyl phthalate, 1 g of modified fiber, and 6 g of pretreated nano-silicon dioxide, ultrasonic dispersion for 30 min under a frequency of 20 Hz to obtain a super leveling acrylic resin composition.

[0076] The preparation method of the modified fiber of the control group is as follows:

[0077] 1) 5.36 g of diphenylmethane diisocyanate and 11.91 g of isophorone diisocyanate were weighed into a four-necked flask, heated to 60°C under a nitrogen atmosphere, and stirred for 30 min. Then, 42.50 g of polytetramethylene ether glycol (PTMEG-2000) was added, the stirring rate was controlled at 80 rpm, and the temperature was raised to 80°C. Then, 0.1 g of dibutyltin dilaurate was added, and the reaction was carried out for 2 h. After the reaction was completed, the temperature of the system was lowered to 70°C, and 2.4 g of 1,4-butanediol was added at a rate of 0.5 g / min. The reaction was continued for 1 h, and then the product was poured into a polytetrafluoroethylene mold. The mold was placed in a vacuum oven, and vacuum degassing was carried out at 100°C for 10 min. Then, curing and drying were carried out at 100°C for 16 h. After the product was crushed, a polyurethane was obtained.

[0078] 2) 2 g of polyurethane and 7.4 g of polyacrylonitrile were weighed into a three-necked flask, 95 g of N,N-dimethylformamide was added, and stirring was carried out at a rate of 100 rpm for 5 h to obtain a spinning solution. The spinning solution was injected into a syringe for electrospinning. During the electrospinning process, the receiving distance was 20 cm, the reciprocating speed of the slide table was 100 cm / min, the voltage of the electric field was 30 kV, and the rotating speed of the drum was 50 rpm. After drying and crushing, a modified fiber with an average length of 40 μm was obtained.

[0079] The preparation method of the pretreated nanosilica in the control group was as follows: 5 g of nanosilica was weighed into a 250 mL three-necked flask, 70 mL of anhydrous toluene was added to the three-necked flask, the three-necked flask was placed in an ultrasonic cleaner, and ultrasonic dispersion was carried out for 15 min. Then, the three-necked flask was placed in an oil bath, 3.8 g of 3-aminopropyltrimethoxysilane was added to the three-necked flask, the temperature was raised to 110°C, and stirring was carried out for 24 h. Then, centrifugal separation, washing, and drying were carried out to obtain pretreated nanosilica.

[0080] Performance detection

[0081] 1. Preparation of the coating film: a tinplate with a size of 120 mm x 50 mm x 0.3 mm was selected as a sample plate, the surface of the sample plate was cleaned with anhydrous ethanol to remove oil stains on the surface of the sample plate, and the cleaned sample plate was dried in a fume hood to remove the solvent. Then, the sample plate was polished with sandpaper with a mesh size of 800, then wiped with acetone, and then placed in a drying oven for drying. 2 g of ethylenediamine and 5 g of n-butanol were mixed uniformly, 20 g of super leveling acrylic resin composition was added, stirred uniformly, aged for 6 min, and then added to a spray gun to form a uniform coating film with a thickness of about 50 μm. Then, the sample plate was dried at room temperature for 7 days to obtain a coating film sample plate for standby use.

[0082] 2. Abrasion resistance test: the abrasion resistance test was carried out according to the standard GB / T 1768-2006.

[0083] 3. Salt fog resistance test: The neutral salt fog resistance of the coating film was tested according to the test method in standard GB / 1771-2007. During the test, the temperature in the salt fog chamber was 35°C, and the concentration of sodium chloride was 50g / L.

[0084] 4. Impact resistance test: The test was performed according to standard GB / T1732-2020. The paint film of the coating film sample was placed flat on the base with the film facing up. The distance between the impact point and the edge of the sample was 15mm, and the distance between the edges of adjacent impact points was 15mm.

[0085] 5. Contact angle test: The water contact angle of the coating film was tested using a contact angle tester. The volume of the water droplet was 5μL. The test results are shown in Table 1. Figure 1

[0086] The performance test data of the coating films made from the super-flat acrylic resin compositions of Examples 1-3 and Control Group 1-2 are shown in Table 1 below:

[0087] Table 1 Test Data

[0088]

[0089] From the analysis of Examples 1-3, Control Group 1-2, and in combination with Table 1 and Figure 1 It can be seen that the use of fluorinated polyurethane as part of the matrix in the modified fiber, and the activation treatment of the composite fiber matrix, significantly improve the mechanical properties, wear resistance, and corrosion resistance of the super-flat acrylic resin composition. In addition, the coating film prepared using the super-flat acrylic resin composition of Example 1-3 has good hydrophobicity.

[0090] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or make equivalent replacements to some of the technical features, as long as they are within the spirit and principles of the present application. Any modifications, equivalent replacements, improvements, etc. made within the scope of the present application should be included in the protection scope of the present application.​

Claims

1. An ultra-flat acrylic resin composition, characterized by: The preparation method comprises the following steps: mixing acrylic ester, styrene, modified fiber and pre-processed nano-silica; the modified fiber is obtained by electrospinning of fluorinated polyurethane and polyacrylonitrile, and then activating the composite fiber matrix; the pre-processed nano-silica is obtained by mixing and reacting nano-silica and amino silane. The activating treatment is to immerse the composite fiber matrix in a sodium thiocyanate aqueous solution, then mix with lye, and react at 70-90 DEG C for 0.5-1 h.

2. The ultra-flat acrylic resin composition according to claim 1, characterized by: The preparation method of the fluorinated polyurethane comprises the following steps: mixing aromatic isocyanate, aliphatic isocyanate and polyether polyol, adding a catalyst to carry out polymerization reaction, then adding perfluoroalkyl alcohol and chain extender to carry out chain extension reaction, solidifying, drying, crushing, and obtaining fluorinated polyurethane.

3. The ultra-flat acrylic resin composition according to claim 1, characterized by: The mass ratio of the fluorinated polyurethane to polyacrylonitrile is 1:(2.5-4).

4. The ultra-flat acrylic resin composition according to claim 1, characterized by: The process parameters of the electrospinning are as follows: receiving distance 18-22 cm, and electric field voltage 28-33 kV.

5. The ultra-flat acrylic resin composition according to claim 1, characterized by: The average length of the composite fiber matrix is 30-60 microns.

6. The ultra-flat acrylic resin composition according to claim 2, characterized by: The molar ratio of the aromatic isocyanate to the aliphatic isocyanate is 1:(1.5-3). The molar ratio of the perfluoroalkyl alcohol to the chain extender is 1:(1-4).

7. The ultra-flat acrylic resin composition according to claim 2, characterized by: The chain extender is one of ethylenediamine, 1,4-butanediol and diethyl toluene diamine.

8. A method of preparing the ultra-flat acrylic resin composition according to claim 1, characterized by: The preparation method comprises the following steps: mixing acrylic ester and styrene, heating to 60-70 DEG C, reacting for 3-5 h, filtering, then adding modified fiber and pre-processed nano-silica, and ultrasonicating to obtain super-flat acrylic resin composition.

9. Use of the ultra-flat acrylic resin composition according to any one of claims 1 to 7 on an automobile. The super-flat resin composition is sprayed on automobile parts, solidified and dried to form a protective film layer; the automobile parts include fenders, chassis and pedals.

Images