A modified polysiloxane self-cleaning coating and a method for preparing the same

Abstract

The application discloses a modified polysiloxane self-cleaning paint and a preparation method thereof, and relates to the technical field of polysiloxane paint. The modified polysiloxane self-cleaning paint comprises the following raw materials in parts by weight: 70-80 parts of polysiloxane epoxy resin, 5-8 parts of modified flame-retardant reinforcing agent, 3-6 parts of toughening agent, 2-3 parts of leveling agent, 1-2 parts of dispersing agent, 2-5 parts of film-forming auxiliary agent, 5-10 parts of curing agent and 20-30 parts of deionized water. The modified polysiloxane self-cleaning paint prepared by the application has good impact resistance, flame retardancy and adhesion.

Description

Technical Field

[0001] This invention relates to the field of polysiloxane coating technology, specifically to a modified polysiloxane self-cleaning coating and its preparation method. Background Technology

[0002] Polysiloxane materials are widely used in building exteriors, industrial equipment, and functional protective coatings due to their excellent weather resistance, high and low temperature resistance, and low surface energy, especially showing promising application prospects in self-cleaning coatings. However, existing polysiloxane self-cleaning coatings still have certain technical shortcomings in practical use. On the one hand, the main chain of polysiloxane is dominated by Si-O bonds. Although it has a certain thermal stability at high temperatures, it is itself a flammable organic polymer material, which is prone to dripping during combustion, resulting in limited flame retardant efficiency. Existing technologies usually improve flame retardant performance by adding inorganic flame retardants, but these flame retardants have poor compatibility with polysiloxane matrices, easily causing agglomeration or migration. This not only affects the transparency and mechanical properties of the coating but may also reduce the self-cleaning effect, posing environmental and safety hazards. On the other hand, functional fillers and modifiers are often introduced into polysiloxane coating systems to improve the wear resistance, flame retardancy and surface functionality of the coating. However, due to the low surface energy and weak polarity of polysiloxane systems, the functional components are not sufficiently dispersed in the system, and sedimentation, stratification or local enrichment are likely to occur, which in turn affects the film uniformity and long-term stability of the coating, limiting its further application in the field of high-performance self-cleaning coatings.

[0003] Chinese invention patent CN119081545A discloses a weather-resistant self-cleaning silicone coating, its preparation method, and its application. The components of the weather-resistant self-cleaning silicone coating include: 50-100 parts of α,ω-dihydroxy polysiloxane, 20-50 parts of alkoxy-modified fluorinated polysiloxane, 20-30 parts of MQ silicone resin, 0.01-0.05 parts of catalyst, and 100-250 parts of solvent oil. The weather-resistant self-cleaning silicone coating prepared by this invention has good self-cleaning effect and adhesion, but its flame retardant properties need to be improved. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a modified polysiloxane self-cleaning coating and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A modified polysiloxane self-cleaning coating comprises the following raw materials in parts by weight: 70-80 parts of polysiloxane epoxy resin, 5-8 parts of modified flame retardant reinforcing agent, 3-6 parts of toughening agent, 2-3 parts of leveling agent, 1-2 parts of dispersant, 2-5 parts of film-forming aid, 5-10 parts of curing agent, and 20-30 parts of deionized water; The modified flame retardant reinforcing agent is prepared by the following method: S1: 2-Furfural, salicylic acid, and paraformaldehyde react to form intermediate 1. S2: 3-Chloropropyl dimethylvinylsilane reacts with 4-(4-hydroxybutylamino)-1-butanol to generate intermediate 2. S3: Intermediate 1 reacts with intermediate 2 to generate intermediate 3. S4: Intermediate 3 reacts with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to generate a modified flame retardant reinforcing agent.

[0006] The dispersant is prepared by the following method: A1: 8-Mercaptooctanoic acid reacts with acetone to form a dicarboxylic acid compound. A2: Dodecyl heptaethylene glycol ether reacts with 2-(6-bromohexyl)ethylene oxide to generate intermediate A. A3: The dicarboxylic compound reacts with intermediate A to generate a dispersant.

[0007] In step S1, the molar ratio of 2-furan methylamine, salicylic acid, and paraformaldehyde is 1:(1.02-1.1):2.

[0008] In step S2, the molar ratio of 3-chloropropyldimethylvinylsilane to 4-(4-hydroxybutylamino)-1-butanol is (1.05-1.1):1.

[0009] In step S3, the molar ratio of intermediate 1 to intermediate 2 is (2.05-2.1):1.

[0010] In step S4, the molar ratio of intermediate 3 to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is (1.05-1.1):1.

[0011] In step A1, the molar ratio of 8-mercaptooctanoic acid to acetone is 2.05:1.

[0012] In step A2, the molar ratio of the dodecyl heptaethylene glycol ether to 2-(6-bromohexyl)ethylene oxide is 1:1.1; in step A3, the molar ratio of the dicarboxylic compound to intermediate A is 1:2.1.

[0013] The curing agent is a water-based epoxy curing agent; the toughening agent is liquid nitrile rubber; the leveling agent is one of polyether-modified polysiloxane and polyester-modified polysiloxane; and the film-forming aid is one of propylene glycol butyl ether and dipropylene glycol butyl ether.

[0014] A method for preparing a modified polysiloxane self-cleaning coating includes the following steps: (1) Weigh out the following by weight: 70-80 parts of polysiloxane epoxy resin, 5-8 parts of modified flame retardant reinforcing agent, 3-6 parts of toughening agent, 2-3 parts of leveling agent, 1-2 parts of dispersant, 2-5 parts of film-forming aid, 5-10 parts of curing agent and 20-30 parts of deionized water; (2) Add deionized water, polysiloxane epoxy resin, modified flame retardant reinforcing agent, toughening agent, leveling agent, dispersant and film-forming aid to the mixer in sequence, and stir; then add curing agent and stir to obtain modified polysiloxane self-cleaning coating.

[0015] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include: The modified polysiloxane self-cleaning coating prepared by this invention has good impact resistance, flame retardancy, and adhesion. Attached Figure Description

[0016] Figure 1 The proton NMR spectrum of intermediate 1 prepared in step S1 of Example 1; Figure 2 The 1H NMR spectrum of intermediate 2 prepared in step S2 of Example 1; Figure 3 The 1H NMR spectrum of intermediate 3 prepared in step S3 of Example 1; Figure 4 The nuclear magnetic resonance hydrogen spectrum of the modified flame retardant enhancer prepared in step S4 of Example 1; Figure 5 The high-resolution mass spectrum of the modified flame retardant enhancer prepared in step S4 of Example 1; Figure 6 The 1H NMR spectrum of the dicarboxylated compound prepared in step A1 of Example 4; Figure 7 The 1H NMR spectrum of intermediate A prepared in step A2 of Example 4; Figure 8 The 1H NMR spectrum of the dispersant prepared in step A3 of Example 4; Figure 9 This is a high-resolution mass spectrum of the dispersant prepared in step A3 of Example 4. Detailed Implementation

[0017] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments.

[0018] Example 1: Preparation of modified flame retardant reinforcing agent: S1: Under nitrogen protection, 0.102 mol of salicylic acid, 0.1 mol of 2-furanylamine, and 0.2 mol of paraformaldehyde were added to the reactor. The mixture was stirred and stirred until homogeneous. The temperature was raised to 100℃ and reacted for 4 h. After cooling to room temperature, the mixture was added to 150 mL of ethyl acetate and extracted three times with deionized water (50 mL each time). The organic phase was dried over 20 g of anhydrous magnesium sulfate, filtered, rotary evaporated at 50℃ for 1 h, and vacuum dried at 50℃ for 12 h to obtain intermediate 1. The reaction equation is shown below: Its proton nuclear magnetic resonance spectrum is as follows Figure 1 As shown, its 1H NMR spectrum data are as follows: 1 H NMR (400 MHz, DMSO- d 6 )δ 12.46 (s, 1H), 7.71 (dd, J = 8.3, 1.2 Hz, 1H), 7.34 – 7.24 (m, 2H), 7.10 (t, J = 8.3 Hz, 1H), 6.32 (m, 1H), 6.17 (dd, J = 5.2, 1.5 Hz, 1H), 4.75 (s,2H), 4.05 (d, J = 2.8 Hz, 2H), 3.90 (d, J = 2.8 Hz, 2H); HRMS (m / z):260.0852[M+H] + .

[0019] S2: Under nitrogen protection, 400 mL of N,N-dimethylformamide (DMF), 0.105 mol of 3-chloropropyldimethylvinylsilane, and 0.1 mol of 4-(4-hydroxybutylamino)-1-butanol were stirred and mixed. 0.012 mol of tetraethylammonium bromide and 0.12 mol of K₂CO₃ were added, and the mixture was heated to 65 °C and reacted for 4 h. After cooling to room temperature, the mixture was filtered and extracted with ethyl acetate (100 mL × 3). The organic phases were combined and washed with saturated brine (100 mL × 2). The mixture was dried over 25 g of anhydrous Na₂SO₄, filtered, and distilled under reduced pressure at 70 °C for 2 h. The mixture was then purified by silica gel column chromatography (using a dichloromethane / methanol mixture as the eluent, with a gradient elution ratio of 20:1 to 10:1). The mixture was distilled under reduced pressure at 50 °C for 2 h and dried under vacuum at 60 °C for 12 h to obtain intermediate 2. The reaction equation is shown below:

[0020] Its proton nuclear magnetic resonance spectrum is as follows Figure 2 As shown, its 1H NMR spectrum data are as follows: 1H NMR (400 MHz, Chloroform- d ) δ 6.06 (m, 1H), 5.73 – 5.38 (m, 2H), 3.61 – 3.48 (m, 4H), 2.79(t, J = 5.9 Hz, 2H), 2.59 – 2.45 (m, 4H), 2.39 (t, J = 6.5 Hz, 2H), 1.65 –1.45 (m, 8H), 1.35 (tt, J = 7.7, 6.5 Hz, 2H), 0.63 (td, J = 7.7, 2.9 Hz, 2H), -0.08 (d, J = 1.0 Hz, 6H); HRMS (m / z):288.2286[M+H] + .

[0021] S3: Under nitrogen protection, 600 ml of toluene, 0.205 mol of intermediate 1, and 0.1 mol of intermediate 2 were added to the reactor and stirred until homogeneous. The mixture was heated to 90 °C, and then 1.5 g of p-toluenesulfonic acid was added. The reaction was allowed to proceed for 6 h (water generated during the reaction was removed using a water separator). The mixture was then cooled to room temperature, and saturated sodium bicarbonate solution was slowly added to adjust the pH to 7. The mixture was stirred thoroughly for 30 min, allowed to stand for separation, and the organic phase was transferred to a rotary evaporator and evaporated at 60 °C for 1 h to obtain intermediate 3. The reaction equation is shown below: Its proton nuclear magnetic resonance spectrum is as follows Figure 3 As shown, its 1H NMR spectrum data are as follows: 1 H NMR (400 MHz, DMSO- d 6)δ 7.70 (dd, J = 8.1, 1.2 Hz, 2H), 7.36 – 7.25 (m, 4H), 7.14 (t, J = 8.2 Hz, 2H), 6.28 (ddt, J = 5.2, 1.9, 1.2 Hz, 2H), 6.21 – 5.98 (m, 3H), 5.76 – 5.39(m, 2H), 4.74 (s, 4H), 4.25 (t, J = 6.1 Hz, 4H), 4.06 (t, J = 0.8 Hz, 4H), 3.93 (d, J = 1.8 Hz, 4H), 2.53 (t, J = 6.0 Hz, 4H), 2.39 (t, J = 6.5 Hz, 2H),1.89 – 1.76 (m, 4H), 1.67 – 1.57 (m, 4H), 1.35 (tt, J = 7.7, 6.5 Hz, 2H), 0.63 (td, J = 7.7, 1.9 Hz, 2H), -0.08 (d, J = 1.0 Hz, 6H); HRMS (m / z):770.3760[M+H] + .

[0022] S4: Add 800 ml xylene, 0.105 mol intermediate 3, and 0.1 mol 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) to the reactor, stir and mix well, heat to 130℃ and react for 8 h, then cool to room temperature. Slowly add the reaction solution dropwise to 1000 mL of ice water for 1 h, stir to precipitate, collect the precipitated solid by vacuum filtration, wash with deionized water (100 ml × 3), add toluene for recrystallization twice (300 ml each time), and dry under vacuum at 80℃ for 12 h to obtain the modified flame retardant reinforcing agent; the reaction equation is shown below: Its proton nuclear magnetic resonance spectrum is as follows Figure 4 As shown, its 1H NMR spectrum data are as follows: 1 H NMR (400 MHz, DMSO- d 6)δ 8.25 (dd, J = 7.4, 1.3 Hz, 1H), 8.08 (dd, J = 7.1, 1.4 Hz, 1H), 7.93 (ddd,J = 6.5, 1.9, 1.4 Hz, 1H), 7.79 (td, J = 7.1, 1.2 Hz, 1H), 7.70 (dd, J = 8.1,1.2 Hz, 2H), 7.62 (td, J = 7.3, 1.4 Hz, 1H), 7.48 – 7.26 (m, 7H), 7.15 (t, J= 8.2 Hz, 2H), 6.32 (ddt, J = 5.2, 1.8, 1.2 Hz, 2H), 6.17 (dd, J = 5.2, 1.5Hz, 2H), 4.75 (s, 4H), 4.21 (t, J = 6.1 Hz, 4H), 4.05 (d, J = 1.9 Hz, 4H), 3.90 (d, J = 1.8 Hz, 4H), 2.54 (t, J = 6.0 Hz, 4H), 2.42 – 2.32 (m, 4H), 1.88– 1.75 (m, 4H), 1.61 (m, 4H), 1.47 – 1.32 (m, 2H), 0.97 (t, J = 9.4 Hz, 2H), 0.59 (t, J = 9.1 Hz, 2H), -0.15 (s, 6H); its high-resolution mass spectrum is as follows: Figure 5 As shown, HRMS (m / z): 986.4095 [M+H] + .

[0023] Example 2: Preparation of modified flame retardant reinforcing agent: S1: Under nitrogen protection, 0.106 mol of salicylic acid, 0.1 mol of 2-furanylamine and 0.2 mol of paraformaldehyde were added to the reactor, stirred and mixed, heated to 105℃ and reacted for 3.5 h, cooled to room temperature, and then added to 150 mL of ethyl acetate. The mixture was extracted three times with deionized water (50 mL each time), dried with 20 g of anhydrous magnesium sulfate, filtered, rotary evaporated at 50℃ for 1 h, and vacuum dried at 50℃ for 12 h to obtain intermediate 1.

[0024] S2: Under nitrogen protection, 400 mL of DMF, 0.108 mol of 3-chloropropyldimethylvinylsilane, and 0.1 mol of 4-(4-hydroxybutylamino)-1-butanol were stirred and mixed. 0.012 mol of tetraethylammonium bromide and 0.12 mol of K2CO3 were added, and the mixture was heated to 70 °C and reacted for 3 h. After cooling to room temperature, the mixture was filtered and extracted with ethyl acetate (100 mL × 3). The organic phases were combined and washed with saturated brine (100 mL × 2). The mixture was dried with 25 g of anhydrous Na2SO4, filtered, and distilled under reduced pressure at 70 °C for 2 h. The mixture was purified by silica gel column chromatography (using a mixed solution of dichloromethane and methanol as the eluent, with a gradient elution ratio of 20:1 to 10:1 by volume). The mixture was distilled under reduced pressure at 50 °C for 2 h and dried under vacuum at 60 °C for 12 h to obtain intermediate 2.

[0025] S3: Under nitrogen protection, add 600 ml of toluene, 0.208 mol of intermediate 1, and 0.1 mol of intermediate 2 to the reactor, stir and mix well, heat to 95°C, then add 1.5 g of p-toluenesulfonic acid, and react for 5 h (use a water separator to remove the generated water during the reaction); cool to room temperature, slowly add saturated sodium bicarbonate solution to adjust the pH to 7, stir thoroughly for 30 min, let stand to separate the layers, transfer the organic phase to a rotary evaporator, and rotary evaporate at 60°C for 1 h to obtain intermediate 3.

[0026] S4: Add 800 ml xylene, 0.108 mol intermediate 3 and 0.1 mol 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to the reactor, stir and mix well, heat to 125℃ and react for 8.5 h, then cool to room temperature, slowly add the reaction solution dropwise to 1000 mL ice water, add for 1 h, stir to precipitate, filter and collect the precipitated solid, wash with deionized water (100 ml × 3), add toluene for recrystallization twice (300 ml each time), and vacuum dry at 80℃ for 12 h to obtain the modified flame retardant reinforcing agent.

[0027] Example 3: Preparation of modified flame retardant reinforcing agent: S1: Under nitrogen protection, 0.11 mol salicylic acid, 0.1 mol 2-furanylamine and 0.2 mol paraformaldehyde were added to the reactor, stirred and mixed, heated to 110℃ and reacted for 3 h, cooled to room temperature, and then added to 150 mL ethyl acetate. The mixture was extracted three times with deionized water (50 mL each time), dried with 20 g anhydrous magnesium sulfate, filtered, rotary evaporated at 50℃ for 1 h, and vacuum dried at 50℃ for 12 h to obtain intermediate 1.

[0028] S2: Under nitrogen protection, 400 mL of DMF, 0.11 mol of 3-chloropropyldimethylvinylsilane, and 0.1 mol of 4-(4-hydroxybutylamino)-1-butanol were stirred and mixed. 0.012 mol of tetraethylammonium bromide and 0.12 mol of K2CO3 were added, and the mixture was heated to 75 °C and reacted for 2 h. After cooling to room temperature, the mixture was filtered and extracted with ethyl acetate (100 mL × 3). The organic phases were combined and washed with saturated brine (100 mL × 2). The mixture was dried with 25 g of anhydrous Na2SO4, filtered, and distilled under reduced pressure at 70 °C for 2 h. The mixture was purified by silica gel column chromatography (using a mixed solution of dichloromethane and methanol as the eluent, with a gradient elution ratio of 20:1 to 10:1). The mixture was distilled under reduced pressure at 50 °C for 2 h and dried under vacuum at 60 °C for 12 h to obtain intermediate 2.

[0029] S3: Under nitrogen protection, add 600 ml of toluene, 0.21 mol of intermediate 1, and 0.1 mol of intermediate 2 to the reactor, stir and mix well, heat to 100℃, then add 1.5 g of p-toluenesulfonic acid, and react for 5 h (use a water separator to remove the generated water during the reaction); cool to room temperature, slowly add saturated sodium bicarbonate solution to adjust the pH to 7, stir thoroughly for 30 min, let stand to separate the layers, transfer the organic phase to a rotary evaporator, and rotary evaporate at 60℃ for 1 h to obtain intermediate 3.

[0030] S4: Add 800 ml xylene, 0.11 mol intermediate 3 and 0.1 mol 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to the reactor, stir and mix well, heat to 120℃ and react for 9 h, then cool to room temperature, slowly add the reaction solution dropwise to 1000 mL ice water, add for 1 h, stir to precipitate, filter and collect the precipitated solid, wash with deionized water (100 ml × 3), add toluene for recrystallization twice (300 ml each time), and vacuum dry at 80℃ for 12 h to obtain the modified flame retardant reinforcing agent.

[0031] Example 4: Preparation of dispersant: A1: 0.205 mol of 8-mercaptooctanoic acid, 0.1 mol of anhydrous acetone, and 4 ml of trifluoroacetic acid were added to the reactor and stirred until homogeneous. The mixture was reacted at room temperature for 6 h. Subsequently, the reaction mixture was cooled in an ice-water bath, and the precipitate was stirred to precipitate. The precipitate was filtered and washed successively with deionized water (50 ml × 3) and n-hexane (50 ml × 3). After vacuum drying at 60 °C for 12 h, a dicarboxylic acid compound was obtained. The reaction equation is shown below: Its proton nuclear magnetic resonance spectrum is as follows Figure 6 As shown, its 1H NMR spectrum data are as follows: 1 H NMR (400 MHz, DMSO- d6 )δ 11.48 (s, 2H), 2.70 (t, J = 5.7 Hz, 4H), 2.26 (t, J = 8.9 Hz, 4H), 1.58 –1.49 (m, 8H), 1.45 (s, 6H), 1.40 – 1.24 (m, 12H); HRMS (m / z):393.2061[M+H] + .

[0032] A2: Under nitrogen protection, 400 ml of toluene and 0.11 mol of 2-(6-bromohexyl)ethylene oxide were added to the reactor and stirred until homogeneous. The temperature was raised to 50°C, and then 0.1 mol of dodecyl heptaethylene glycol ether was added and stirred until homogeneous. At 50°C, 10 ml of a toluene solution containing 1.0 g of boron trifluoride ether was slowly added dropwise over 20 min. After the addition was complete, the temperature was raised to 90°C and reacted for 6 h. Then, the temperature was lowered to 0°C, and saturated sodium bicarbonate solution was slowly added dropwise to adjust the pH to 7. The mixture was allowed to stand and separate into layers. The aqueous phase was discarded, and the organic phase was taken and washed twice with saturated brine (100 ml each time). 500 ml of cyclohexane was added, stirred, and the precipitate was precipitated. The precipitate was then washed three times with cyclohexane (50 ml each time) and dried under vacuum at 40°C for 12 h to obtain intermediate A. The reaction equation is shown below: Its proton nuclear magnetic resonance spectrum is as follows Figure 7 As shown, its proton NMR spectrum data are as follows: 1 H NMR (400 MHz, Chloroform- d ) δ 3.94 – 3.87 (m, 2H), 3.75 – 3.61 (m, 28H), 3.55 – 3.34 (m,5H), 3.11 (d, J = 6.1 Hz, 1H), 1.90 – 1.80 (m, 2H), 1.70 – 1.20 (m, 28H),0.93 – 0.85 (m, 3H); HRMS (m / z):701.4132[M+H] + .

[0033] A3: Under nitrogen protection, 1000 ml of toluene, 0.1 mol of dicarboxylic acid compound, and 0.21 mol of intermediate A were added to the reactor and stirred until homogeneous. The mixture was heated to 100°C, and then 1.5 g of p-toluenesulfonic acid was added. The reaction was allowed to proceed for 5 hours (water generated during the reaction was removed using a water separator). The mixture was then cooled to room temperature, and saturated sodium bicarbonate solution was slowly added to adjust the pH to 7. The mixture was stirred thoroughly for 30 minutes, allowed to stand for separation, and the organic phase was transferred to a rotary evaporator and distilled under reduced pressure at 60°C for 1 hour to obtain the dispersant. The reaction equation is shown below: Its proton nuclear magnetic resonance spectrum is as follows Figure 8 As shown, its 1H NMR spectrum data are as follows: 1 H NMR (400 MHz, Chloroform- d δ 4.78 (tt, J = 6.8, 5.0 Hz, 2H), 4.09 – 3.95 (m, 4H), 3.91 – 3.42 (m, 64H), 2.71 (t, J = 5.7 Hz, 4H), 2.38 – 2.22 (m, 4H), 1.93 – 1.66 (m, 6H), 1.59 – 1.24 (m, 80H), 0.92 – 0.83 (m, 6H); its high-resolution mass spectrum is shown below. Figure 9 As shown, HRMS (m / z): 1760.0079 [M+H] + .

[0034] Example 5: Preparation of modified polysiloxane self-cleaning coating: (1) Weigh out: 700g of polysiloxane epoxy resin, 50g of modified flame retardant reinforcing agent (prepared in Example 1), 30g of toughening agent (liquid nitrile rubber), 20g of leveling agent (polyether modified polysiloxane), 10g of dispersant (prepared in Example 4), 20g of film-forming aid (propylene glycol butyl ether), 50g of curing agent (waterborne epoxy curing agent), and 200g of deionized water; (2) Add deionized water, polysiloxane epoxy resin, modified flame retardant reinforcing agent, toughening agent, leveling agent, dispersant and film-forming aid to the mixer in sequence, and stir at 500 r / min for 20 min; then add curing agent and stir at 300 r / min for 20 min to obtain modified polysiloxane self-cleaning coating.

[0035] Example 6: Preparation of modified polysiloxane self-cleaning coating: (1) Weigh out: 750g of polysiloxane epoxy resin, 70g of modified flame retardant reinforcing agent (prepared in Example 2), 45g of toughening agent (liquid nitrile rubber), 25g of leveling agent (polyether modified polysiloxane), 15g of dispersant (prepared in Example 4), 30g of film-forming aid (propylene glycol butyl ether), 80g of curing agent (waterborne epoxy curing agent), and 250g of deionized water; (2) Add deionized water, polysiloxane epoxy resin, modified flame retardant reinforcing agent, toughening agent, leveling agent, dispersant and film-forming aid to the mixer in sequence, and stir at 500 r / min for 20 min; then add curing agent and stir at 300 r / min for 20 min to obtain modified polysiloxane self-cleaning coating.

[0036] Example 7: Preparation of modified polysiloxane self-cleaning coating: (1) Weigh out: 800g of polysiloxane epoxy resin, 80g of modified flame retardant reinforcing agent (prepared in Example 3), 60g of toughening agent (liquid nitrile rubber), 30g of leveling agent (polyether modified polysiloxane), 20g of dispersant (prepared in Example 4), 50g of film-forming aid (dipropylene glycol butyl ether), 100g of curing agent (waterborne epoxy curing agent), and 300g of deionized water; (2) Add deionized water, polysiloxane epoxy resin, modified flame retardant reinforcing agent, toughening agent, leveling agent, dispersant and film-forming aid to the mixer in sequence, and stir at 500 r / min for 20 min; then add curing agent and stir at 300 r / min for 20 min to obtain modified polysiloxane self-cleaning coating.

[0037] Comparative Example 1 The raw material ratio and preparation method of the modified polysiloxane self-cleaning coating are basically the same as those in Example 6, except that the modified flame retardant reinforcing agent is replaced with an equal weight of the modified flame retardant reinforcing agent prepared by the following method: The preparation method of the modified flame retardant reinforcing agent is basically the same as that in Example 2, except that 2-furan methylamine in step S1 is replaced with an equimolar amount of n-butylamine.

[0038] Comparative Example 2 The raw material ratio and preparation method of the modified polysiloxane self-cleaning coating are basically the same as those in Example 6, except that the modified flame retardant reinforcing agent is replaced with an equal weight of the modified flame retardant reinforcing agent prepared by the following method: The preparation method of the modified flame retardant reinforcing agent is basically the same as that in Example 2, except that 4-(4-hydroxybutylamino)-1-butanol in step S2 is replaced with an equimolar amount of diethanolamine.

[0039] Comparative Example 3 The raw material ratio and preparation method of the modified polysiloxane self-cleaning coating are basically the same as those in Example 6, except that the modified flame retardant reinforcing agent is replaced with an equal weight of the modified flame retardant reinforcing agent prepared by the following method: The preparation method of the modified flame retardant reinforcing agent is basically the same as that in Example 2, except that 4-(4-hydroxybutylamino)-1-butanol in step S2 is replaced with an equimolar amount of 4-ethylamino-1-butanol; and in step S3, the amount of intermediate 1 fed is 0.108 mol.

[0040] Comparative Example 4 The raw material ratio and preparation method of the modified polysiloxane self-cleaning coating are basically the same as those in Example 6, except that the modified flame retardant reinforcing agent is replaced with an equal weight of the modified flame retardant reinforcing agent prepared by the following method: The preparation method of the modified flame retardant reinforcing agent is basically the same as that in Example 2, except that in step S2, 3-chloropropyldimethylvinylsilane is replaced with an equimolar amount of 6-chloro-1-hexene.

[0041] Comparative Example 5 The raw material ratio and preparation method of the modified polysiloxane self-cleaning coating are basically the same as those in Example 6, except that the dispersant is replaced with an equal weight of a dispersant prepared by the following method: The preparation method of the dispersant is basically the same as that in Example 4, except that 8-mercaptooctanoic acid in step A1 is replaced with an equimolar amount of thiolactic acid.

[0042] Comparative Example 6 The raw material ratio and preparation method of the modified polysiloxane self-cleaning coating are basically the same as those in Example 6, except that the dispersant is replaced with an equal weight of a dispersant prepared by the following method: The preparation method of the dispersant is basically the same as that in Example 4, except that the dodecyl heptaethylene glycol ether in step A2 is replaced with an equimolar amount of dodecyl diethylene glycol ether.

[0043] Comparative Example 7 The raw material ratio and preparation method of the modified polysiloxane self-cleaning coating are basically the same as those in Example 6, except that the dispersant is replaced with an equal weight of a dispersant prepared by the following method: The preparation method of the dispersant is basically the same as that in Example 4, except that the dodecyl heptaethylene glycol ether in step A2 is replaced with an equimolar amount of dodecyl alcohol.

[0044] The polysiloxane epoxy resin used in the embodiments and comparative examples of this application is SH-9614 type epoxy-modified polysiloxane resin, produced by Hubei Longsheng Sihai New Material Co., Ltd.; the polyether-modified polysiloxane is BYK-333; the polyester-modified polysiloxane is BYK-310; the liquid nitrile rubber is GREENBABY®LR-LNBR820; the waterborne epoxy curing agent is TC-3870 waterborne epoxy curing agent, produced by Bath Synthetic New Materials (Shenzhen) Co., Ltd.; paraformaldehyde was purchased from Maclean, item number P804536-500g, reagent grade.

[0045] The modified polysiloxane self-cleaning coatings prepared in the examples and comparative examples were tested for impact resistance, flame retardancy, and adhesion. The test results are shown in Table 1.

[0046] Sample preparation: First, the tinplate sample (120mm×50mm×0.2mm) was sanded using 800-grit sandpaper in one direction. After rotating the substrate 90°, the sanding continued. The surface of the metal substrate was rinsed with anhydrous ethanol to remove stains, then wiped with degreased cotton and cleaned with acetone. The sample was dried with a blower and finally rinsed three times with anhydrous ethanol and dried for later use. The tinplate sample was fixed on a horizontal table, and the self-cleaning coating was evenly applied to the surface of the tinplate sample using a wire bar coater. The coating thickness was 25μm. After the coating was completed, the sample was placed in an environment with room temperature and 50% relative humidity to dry for 48 hours before testing.

[0047] Impact resistance test: Referring to GB / T 1732-2020 "Test Method for Impact Resistance of Coating Film", the modified polysiloxane self-cleaning coatings prepared in the examples and comparative examples were subjected to a forward impact test using a coating film impactor. The cured sample plate was placed flat on the base of the impactor, and a 1kg weight was dropped freely from a height of 30cm to impact the coating. After the test, the sample plate was removed, and the impact point was observed with a magnifying glass for cracks, wrinkles, and peeling. If no cracks, wrinkles, or peeling were observed, the test was repeated at higher positions (each time the height increased by 5cm or multiples of 5cm) until cracks, wrinkles, and peeling were observed. If cracks, wrinkles, and peeling were observed, the test was repeated at lower positions (each time decreasing by 1cm) until no cracks, wrinkles, or peeling were observed. The result is expressed as the maximum height (cm) at which no cracks, wrinkles, or peeling were observed in three tests.

[0048] Flame retardant performance test: Modified polysiloxane self-cleaning coating was applied to a 300mm×150mm×5mm three-layer plywood with a coating ratio of 250g / m². 2 After drying at 130℃ for 40 hours in a drying oven, the sample was cooled to room temperature. The sample was fixed on a support with the coating tilted downwards at a 45° angle to the ground. A fuel cup, made of brass, with an outer diameter of 24 mm, a wall thickness of 1 mm, a height of 17 mm, and a volume of 6 ml, was prepared. 5 ml of anhydrous ethanol was injected into the fuel cup using a dropper. The closest vertical distance from the rim of the fuel cup to the surface of the sample was 25 mm. The sample was ignited until the flame self-extinguished. Five samples were repeated for each test group. The burned sample was removed, and it was sawn into four pieces along the line of maximum flame propagation length and width. The length and width of the charred (significantly blackened) substrate under the coating at the longitudinal and transverse cuts were measured, along with the maximum char depth. The char volume was calculated, and the average of the char volumes of the five samples was taken as the final char volume. The calculation formula is as follows:

[0049] Where: V—carbonization volume, cm 3 ; —Carbonization length, cm; —Carburization width, cm; —Carbonization depth, cm; n—Number of samples.

[0050] Adhesion Test: Referring to GB / T 9286-2021 "Cross-cut Test for Paint and Varnish Films", the modified polysiloxane self-cleaning coatings prepared in the examples and comparative examples were subjected to adhesion tests. A 5×5 grid pattern (6 horizontal lines, 6 vertical lines, 1mm spacing, penetrating to the substrate) was cut into the paint film using a single-edged cross-cutting tool. Debris was brushed away, and special pressure-sensitive adhesive tape was applied and quickly peeled off. The degree of paint film peeling off in the grid areas was observed. Adhesion was graded from best to worst as 0-5, with 0 representing the best and 5 representing the worst.

[0051] Anti-fouling test: Nano-activated carbon (model HNACB-200, produced by Shanghai Hainuo Carbon Industry Co., Ltd.) was used as a simulated pollutant. Activated carbon particles were spread on the coating surface at a 45° angle. A 50μL water droplet was passed over the coating surface, and the ability of the droplet to carry the particles away from the coating surface without leaving a trace was observed. If the liquid completely carries away the particles from the coating surface, restoring the surface to cleanliness, it indicates that it has self-cleaning properties. Anti-fouling performance is divided into three levels, as follows:

[0052] By means that as the water droplets roll, they can completely remove all the nano-activated carbon particles, restoring the coating surface to a smooth finish without leaving any visible marks or water lines.

[0053] Basically passed: Water droplets can carry away most particles, but may leave a few traces or slight water stains.

[0054] Failure: The water droplets cannot effectively remove the particles. The particles adhere to the surface or are pushed away by the water droplets but leave stains. In some cases, the water droplets themselves are contaminated and remain on the surface.

[0055] Table 1 Performance Indicators of Modified Polysiloxane Self-Cleaning Coatings As can be seen from Table 1, the modified polysiloxane self-cleaning coating prepared in this application has good impact resistance, flame retardancy, and adhesion.

[0056] The modified flame retardant reinforcing agent prepared in this invention introduces three key functional groups: phosphaphenanthrene, organosilicon segments, and an aromatic / furan rigid framework. These functional groups work synergistically to improve the flame retardancy and impact resistance of the material. Regarding flame retardancy, the DOPO group interrupts the chain reaction by capturing combustion free radicals. Simultaneously, it generates a "phosphorus-silicon synergistic effect" with the organosilicon segments. The phosphorus component promotes early and abundant char formation, while the silicon component migrates to the material surface during combustion, combining with the char layer to form a dense, robust, and heat-insulating silicon-carbon protective barrier. This barrier effectively insulates against heat and oxygen and prevents dripping, thereby enhancing flame retardant performance. Under impact, the flexible alkyl chain acts as an "energy dissipation unit" through chain segment movement, conformational change, and reversible deformation, effectively absorbing and dispersing impact energy and preventing crack initiation. Meanwhile, the rigid aromatic ring, as a "reinforcing skeleton," is uniformly dispersed in the network, preventing the propagation of microcracks. At the same time, the rigid aromatic structure of the phosphenanthrene (DOPO) group provides a certain degree of rigid support and π-π stacking effect, which helps maintain the basic strength of the coating. In addition, the rigidity of the furan ring and the moderate flexibility of the ester bond together construct a "rigid-flexible" network structure, achieving a synergistic improvement in strength and toughness.

[0057] In Comparative Example 1, replacing 2-furanmethylamine with n-butylamine resulted in a decrease in coating performance due to the lack of a rigid aromatic / heterocyclic skeleton. The furan ring introduced by 2-furanmethylamine is a rigid aromatic heterocyclic structure, which serves as a highly efficient char source and char layer skeleton at high temperatures, promoting the formation of a dense and robust heat-insulating char layer and enhancing the thermal stability and mechanical strength of the matrix. Simultaneously, this aromatic structure generates a phosphorus-aromatic ring synergistic effect with the phosphaphenanthrene group, further improving flame retardant efficiency. In contrast, n-butylamine only introduces flexible aliphatic chains, which have poor thermal stability and are prone to pyrolysis and volatilization, making it difficult to provide an effective char-forming skeleton, resulting in a loose char layer with insufficient strength. Furthermore, the introduction of aliphatic chains reduces molecular polarity and compatibility with the resin matrix, causing uneven dispersion.

[0058] The dispersant prepared in this invention uses a thiolated skeleton as its core, linking polyether segments and long-chain alkyl groups via ester bonds. The molecule simultaneously contains thioether groups, ether bonds, and hydrophobic alkyl groups, forming a multifunctional dispersant with both polar anchoring and hydrophobic flexibility. The CS bonds in the dispersant provide molecular chain flexibility, helping to buffer external stress and improve the impact resistance of the coating; the polarity of sulfur atoms can form weak coordination or secondary bonding with metal oxides or polar substrate surfaces, enhancing coating adhesion; the thioether groups improve the dispersion uniformity of the dispersant in the coating system, increasing the surface finish of the material; simultaneously, the polyether segments provide good flexibility and interfacial wetting ability, which is beneficial for buffering external impacts and uniformly dispersing stress; while the long-chain alkyl groups enhance the compatibility and cohesion of the molecule in the organic coating system. The synergistic effect of multiple functional groups within the molecule enables the coating to maintain self-cleaning and hydrophobic properties while achieving higher adhesion and superior impact resistance.

[0059] The main reason for the significant performance degradation in Comparative Example 7, where dodecyl heptaethylene glycol ether was replaced with an equimolar amount of dodecyl alcohol in the dispersant preparation step, is that dodecyl alcohol lacks the steric stabilization and hydrophilic anchoring capabilities unique to polyether segments. The molecular structure of dodecyl heptaethylene glycol ether contains hydrophilic polyether segments and hydrophobic dodecyl chains, enabling it to form a steric barrier on the pigment particle surface through hydration, preventing particle aggregation. Simultaneously, its ether oxygen atoms can form hydrogen bonds with the particle surface, ensuring dispersion stability. In contrast, dodecyl alcohol only contains long-chain alkyl groups, exhibiting strong hydrophobicity and difficulty in forming an effective steric hindrance layer in polar systems. Its weaker binding force to the particle surface leads to a decline in coating performance.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A modified polysiloxane self-cleaning coating, characterized in that, The ingredients include the following parts by weight: 70-80 parts of polysiloxane epoxy resin, 5-8 parts of modified flame retardant reinforcing agent, 3-6 parts of toughening agent, 2-3 parts of leveling agent, 1-2 parts of dispersant, 2-5 parts of film-forming aid, 5-10 parts of curing agent, and 20-30 parts of deionized water; The modified flame retardant reinforcing agent is prepared by the following method: S1: 2-Furfural, salicylic acid, and paraformaldehyde react to form intermediate 1. S2: 3-Chloropropyl dimethylvinylsilane reacts with 4-(4-hydroxybutylamino)-1-butanol to generate intermediate 2. S3: Intermediate 1 reacts with intermediate 2 to generate intermediate 3. S4: Intermediate 3 reacts with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to generate a modified flame retardant reinforcing agent; The dispersant is prepared by the following method: A1: 8-Mercaptooctanoic acid reacts with acetone to form a dicarboxylic acid compound. A2: Dodecyl heptaethylene glycol ether reacts with 2-(6-bromohexyl)ethylene oxide to generate intermediate A. A3: The dicarboxylic compound reacts with intermediate A to generate a dispersant.

2. The modified polysiloxane self-cleaning coating according to claim 1, characterized in that, In step S1, the molar ratio of 2-furan methylamine, salicylic acid, and paraformaldehyde is 1:(1.02-1.1):

2.

3. The modified polysiloxane self-cleaning coating according to claim 1, characterized in that, In step S2, the molar ratio of 3-chloropropyldimethylvinylsilane to 4-(4-hydroxybutylamino)-1-butanol is (1.05-1.1):

1.

4. The modified polysiloxane self-cleaning coating according to claim 1, characterized in that, In step S3, the molar ratio of intermediate 1 to intermediate 2 is (2.05-2.1):

1.

5. The modified polysiloxane self-cleaning coating according to claim 1, characterized in that, In step S4, the molar ratio of intermediate 3 to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is (1.05-1.1):

1.

6. The modified polysiloxane self-cleaning coating according to claim 1, characterized in that, In step A1, the molar ratio of 8-mercaptooctanoic acid to acetone is 2.05:

1.

7. The modified polysiloxane self-cleaning coating according to claim 1, characterized in that, In step A2, the molar ratio of the dodecyl heptaethylene glycol ether to 2-(6-bromohexyl)ethylene oxide is 1:1.1; in step A3, the molar ratio of the dicarboxylic compound to intermediate A is 1:2.

1.

8. The modified polysiloxane self-cleaning coating according to claim 1, characterized in that, The curing agent is a water-based epoxy curing agent; the toughening agent is liquid nitrile rubber; the leveling agent is one of polyether-modified polysiloxane and polyester-modified polysiloxane; and the film-forming aid is one of propylene glycol butyl ether and dipropylene glycol butyl ether.

9. A method for preparing the modified polysiloxane self-cleaning coating according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Weigh out the following by weight: 70-80 parts of polysiloxane epoxy resin, 5-8 parts of modified flame retardant reinforcing agent, 3-6 parts of toughening agent, 2-3 parts of leveling agent, 1-2 parts of dispersant, 2-5 parts of film-forming aid, 5-10 parts of curing agent and 20-30 parts of deionized water; (2) Add deionized water, polysiloxane epoxy resin, modified flame retardant reinforcing agent, toughening agent, leveling agent, dispersant and film-forming aid to the mixer in sequence, and stir; then add curing agent and stir to obtain modified polysiloxane self-cleaning coating.

Images