Waterproof and corrosion-resistant polyvinyl chloride composite film and preparation method thereof

Abstract

The application relates to the technical field of film materials, in particular to a waterproof and corrosion-resistant polyvinyl chloride composite film and a preparation method thereof. The waterproof and corrosion-resistant polyvinyl chloride composite film comprises a substrate layer and a PVC protective layer; the PVC protective layer is coated on the surface of the substrate layer; according to weight fractions, the PVC protective layer comprises the following raw materials: 50-70 parts of polyvinyl chloride, 20-40 parts of a plasticizer, 5-10 parts of modified montmorillonite, 5-15 parts of an additive and 1-5 parts of a heat stabilizer. The composite film has high hydrophobicity, high flame retardance and excellent corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of membrane materials technology, and in particular to a waterproof and corrosion-resistant polyvinyl chloride composite membrane and its preparation method. Background Technology

[0002] Polyvinyl chloride (PVC) composite membranes are multilayer membrane materials composed of a PVC protective layer and a substrate layer. Due to their low cost, good processability, and high mechanical strength, they are widely used in building waterproofing membranes, decorative films, packaging materials, and agricultural greenhouse coverings. In these applications, composite membranes are often exposed to the outdoor environment for extended periods, facing the combined effects of rainwater erosion, humid air, acid rain, microorganisms, and various corrosive media. Therefore, high requirements are placed on their waterproof and corrosion-resistant properties.

[0003] While traditional PVC composite membranes possess a certain degree of water resistance due to their relatively low surface energy, which can prevent short-term water penetration to some extent, water molecules can still gradually seep into the membrane layer through micropores, interface defects, or capillary action under long-term rain or high-pressure water conditions. This can lead to moisture absorption in the substrate layer, blistering or even peeling of the protective layer, severely impacting its service life. Furthermore, bacteria, mold, and acidic / alkaline pollutants from industrial emissions can easily accumulate on the membrane surface and cause localized corrosion. In particular, small molecule components such as plasticizers in the PVC protective layer may migrate to the surface under humid and hot conditions, further accelerating the corrosion process. Therefore, there is an urgent need to develop PVC composite membranes that combine durable water resistance with corrosion resistance. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a waterproof and corrosion-resistant polyvinyl chloride composite membrane, which has high hydrophobicity, high flame retardancy and excellent corrosion resistance.

[0005] The second objective of this invention is to provide a method for preparing a waterproof and corrosion-resistant polyvinyl chloride composite membrane. This method is simple in process, has mild operating conditions, and is easy to achieve continuous and large-scale production.

[0006] One of the objectives of this invention is achieved through the following technical solution: A waterproof and corrosion-resistant polyvinyl chloride composite film includes a substrate layer and a PVC protective layer; the PVC protective layer is coated on the surface of the substrate layer; by weight, the PVC protective layer includes the following raw materials: 50-70 parts of polyvinyl chloride, 20-40 parts of plasticizer, 5-10 parts of modified montmorillonite, 5-15 parts of additives, and 1-5 parts of heat stabilizer. The structural formula of the auxiliary agent is: .

[0007] Furthermore, the preparation process of the auxiliary agent is as follows: (1) Add ethylenediamine to acetone, then add an acetone solution of dichlorodiphenylsilane, and purify after reaction to obtain intermediate 1; The structural formula of intermediate 1 is: (2) Add intermediate 1, triethylamine and paraformaldehyde to a mixed solvent, then add conifer alcohol, stir to react, heat and continue to react, and purify after reaction to obtain intermediate 2. The structural formula of intermediate 2 is as follows: (3) The intermediate 2 is added to toluene, and then a catalyst and bistrimethylsiloxymethylsilane are added. After the reaction, the mixture is purified to obtain the auxiliary agent.

[0008] The preparation principle of the additive of the present invention is as follows: using dichlorodiphenylsilane as raw material, it is first reacted with ethylenediamine to obtain an amino-containing intermediate 1; then intermediate 1 is condensed and cyclized with formaldehyde and coniferyl alcohol to introduce a benzoxazine structure to obtain intermediate 2; finally, the additive is obtained by hydrosilylation reaction of the double bond of the side chain of intermediate 2 with bistrimethylsiloxymethylsilane.

[0009] Further, in step (1), the molar ratio of dichlorodiphenylsilane to ethylenediamine is 1:(3.6-4); the concentration of the acetone solution of dichlorodiphenylsilane is 2.5 mol / L, and the temperature at which it is added is 0-5℃; the volume ratio of ethylenediamine to acetone is 1 mol:(1-1.1) L; the reaction temperature is 20-25℃, and the time is 14-16 h; in step (2), the molar ratio of intermediate 1, coniferyl alcohol, paraformaldehyde, and triethylamine is 1:(2-2.1):(4-4.2):(2-2.1); the mixed solvent is composed of ethanol and toluene in a volume ratio of 2:1; the stirring reaction temperature is 30-45℃, and the time is 30-45 min; the temperature is raised to 90-95℃, and the reaction continues for 5-8 h.

[0010] Furthermore, in step (3), the molar ratio of intermediate 2 and bistrimethylsiloxymethylsilane is 1:(2.2-2.6); the amount of catalyst added is 0.05-0.1 wt% of the total mass of the reactants; the catalyst is a platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, and the temperature at which it is added is 70-80℃; the reaction temperature is 80-100℃, and the time is 6-8h.

[0011] Furthermore, the preparation process of the modified montmorillonite is as follows: (a) Pretreated montmorillonite was added to N,N-dimethylformamide, followed by the addition of 5-aminophenyl-1,3-dicarboxynitrile and triethylamine. After reaction, the mixture was purified to obtain cyano-modified montmorillonite. (b) The cyano-modified montmorillonite was added to 1,2-dichlorobenzene, followed by the addition of 2-aminopyridine, cuprous bromide, 1,10-phenanthroline and zinc iodide. After stirring and reacting, the mixture was purified to obtain the modified montmorillonite.

[0012] The preparation principle of the modified montmorillonite of this invention is as follows: Montmorillonite is first pretreated by silanization with 3-chloropropyltrimethoxysilane, and then a cyano group is introduced by nucleophilic substitution reaction with 5-aminophenyl-1,3-dicarboxynitrile to obtain cyano-modified montmorillonite; finally, the cyano group undergoes a cyclization reaction with 2-aminopyridine to construct a nitrogen-containing triazolidine heterocycle, thus obtaining the modified montmorillonite.

[0013] Further, in step (a), the ratio of the amount of pretreated montmorillonite, 5-aminophenyl-1,3-dicarboxynitrile, and triethylamine is 1 g : (0.6-1.2) g : (0.5-1) mL; the reaction temperature is 80-85℃ and the time is 7-10 h; in step (b), the mass ratio of cyano-modified montmorillonite, 2-aminopyridine, cuprous bromide, 1,10-phenanthroline, and zinc iodide is 1 : (0.45-0.9) : (0.03-0.06) : (0.036-0.072) : (0.13-0.26); the stirring reaction temperature is 130-135℃ and the time is 24-36 h.

[0014] Furthermore, the preparation process of the pretreated montmorillonite is as follows: 3-Chloropropyltrimethoxysilane was added to an aqueous methanol solution, the pH was adjusted, the reaction was stirred, montmorillonite was added, the reaction was continued, and then purified to obtain the pretreated montmorillonite.

[0015] Furthermore, the mass ratio of montmorillonite to 3-chloropropyltrimethoxysilane is 1:(0.4-0.8); the pH is adjusted to 5-5.5; the stirring reaction temperature is 60-65℃ for 1-2 hours; the reaction continues for 4-8 hours; and the volume fraction of the methanol-water solution is 85%.

[0016] Furthermore, the polyvinyl chloride is polyvinyl chloride paste resin; the heat stabilizer is a calcium-zinc composite stabilizer; the plasticizer is selected from one of dioctyl terephthalate, epoxidized soybean oil, and diisononyl phthalate; and the substrate layer is made of nylon fiber cloth.

[0017] Furthermore, the thickness of the PVC protective layer is 0.06-0.15 mm.

[0018] Furthermore, the calcium-zinc composite stabilizer is designated as model BPR91662SP / 3.

[0019] The second objective of this invention is achieved by the following technical solution: The preparation method of the above-mentioned waterproof and corrosion-resistant polyvinyl chloride composite membrane includes the following steps: Polyvinyl chloride, plasticizer, modified montmorillonite, additives and heat stabilizer are mixed evenly and then coated on the surface of the substrate layer to obtain a PVC protective layer. After plasticizing, the product is obtained.

[0020] Furthermore, the plasticizing temperature is 160-165℃, and the time is 15-20 minutes.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention provides a waterproof and corrosion-resistant polyvinyl chloride composite membrane, which has high hydrophobicity, high flame retardancy and excellent corrosion resistance.

[0022] (2) This invention improves the hydrophobicity and flame retardant properties of the composite film by adding an additive with a specific structure. The benzoxazine structure in the additive has a low surface free energy, while heptamethyltrisiloxane is a classic hydrophobic group. The synergistic effect of the two forms a strong hydrophobic layer on the surface of the composite film, significantly reducing the water contact angle and effectively preventing water molecule penetration and capillary absorption. In addition, the benzoxazine structure contains stable nitrogen-oxygen heterocycles, which can release inert gases such as ammonia (NH3) when thermally decomposed, diluting the concentration of combustible gases, while promoting the formation of a continuous and dense carbon layer on the matrix, isolating oxygen and heat, and inhibiting further thermal decomposition and combustion of PVC. The long chains of diphenylsilane and trisiloxane in the additive molecule migrate to the surface of the material at high temperatures, quickly forming a dense and stable silicon carbide ceramic layer to isolate oxygen, inhibit heat transfer, and prevent molten dripping, thereby enhancing the flame retardant effect. At the same time, the polar groups such as imine (-NH-) in the additive can also have a moderate affinity with the polar groups in PVC, which helps to improve its compatibility and dispersibility.

[0023] (3) This invention improves the corrosion resistance, hydrophobicity, and thermal stability of the composite membrane by adding modified montmorillonite. The triazolidine nitrogen-containing heterocycle in the modified montmorillonite is hydrophobic, has good chemical stability and a rigid structure, and can withstand the erosion of acids, alkalis and various chemical media; the montmorillonite sheets extend the penetration path of corrosive agents through physical barrier effects, and the two work synergistically to effectively improve the corrosion resistance of the composite membrane. In addition, the montmorillonite sheets can block the diffusion of thermo-oxidative aging agents into the matrix, and the weakly basic sites of the triazolidine nitrogen-containing heterocycle can help alleviate the local acidic environment. Together with the heat stabilizer in the formulation, they further improve the weather resistance of the composite membrane.

[0024] (4) The present invention provides a method for preparing a waterproof and corrosion-resistant polyvinyl chloride composite membrane. The method is simple, the operating conditions are mild, and it is easy to achieve continuous and large-scale production. Attached Figure Description

[0025] Figure 1 SEM image of the modified montmorillonite prepared in Example 4. Detailed Implementation

[0026] The present invention will now be further described with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0027] In the following examples or comparative examples, the calcium-zinc composite stabilizer is model BPR91662SP / 3.

[0028] Preparation Example 1 The preparation process of the additive is as follows: (1) With a volume ratio of ethylenediamine to acetone of 0.2 mol: 210 mL, ethylenediamine was dissolved in acetone, and a 2.5 mol / L solution of dichlorodiphenylsilane in acetone was added dropwise at 4 °C, wherein the volume ratio of dichlorodiphenylsilane to ethylenediamine was 0.05 mol: 0.19 mol. After the addition was complete, the mixture was reacted at 22 °C for 15 h. The mixture was filtered to remove impurities, and acetone and excess ethylenediamine were removed by vacuum distillation. The residue was purified by column chromatography (V 乙酸乙酯 V 石油醚 =3:1, add 1% volume of triethylamine), to obtain intermediate 1 (yield 80%); NMR and mass spectrometry results of intermediate 1 are as follows: 1 HNMR: (C 16 H 24 N4Si, 400MHz, DMSO- d6 ) δ: 1.5 (s, 6H), 2.74-2.78 (m, 4H), 2.89-2.93 (m, 4H), 7.35-7.39 (m, 6H), 7.44-7.48 (m, 4H). MS (ESI) m / z=300.18 [M].

[0029] (2) Using intermediate 1, coniferol, paraformaldehyde, triethylamine, and mixed solvent in a ratio of 0.02 mol: 0.041 mol: 0.082 mol: 0.041 mol: 90 mL, intermediate 1, triethylamine, and paraformaldehyde were added to a mixed solvent (composed of ethanol and toluene in a volume ratio of 2:1). After mixing thoroughly, coniferol was added, and the mixture was stirred at 72 °C for 40 min. Then, the mixture was heated to 93 °C and the reaction was continued for 7 h. After the reaction was completed, the mixture was cooled to room temperature and extracted with ethyl acetate and 1 mol / L NaOH aqueous solution. The organic phase was washed with deionized water, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified by column chromatography (V 乙酸乙酯 V 石油醚 =2:1, add 1% volume of triethylamine), to obtain intermediate 2 (yield 80%); NMR and mass spectrometry results of intermediate 2 are as follows: 1 HNMR: (C 40 H 48 O6N4Si, 400MHz, DMSO- d6 ) δ: 1.5 (s, 2H), 2.51-2.55 (t, 4H), 2.73-2.77 (t, 4H), 3.70 (s, 4H), 3.83 (s, 6H), 4.16-4.20 (d, 4H), 5.01 (s, 4H), 5 .05 (s, 2H), 6.23-6.27 (m, 2H), 6.63-6.67 (d, 2H), 6.96 (s, 2H), 7.20 (s, 2H), 7.35-7.39 (m, 6H), 7.44-7.48 (m, 4H). MS (ESI) m / z=708.33 [M].

[0030] (3) Intermediate 2, bis(trimethylsiloxymethylsilane), and toluene were used in a ratio of 0.5 mmol: 1.2 mmol: 90 mL. Intermediate 2 was dissolved in toluene, and the mixture was heated to 75 °C under nitrogen protection. 0.08 wt% of platinum(O)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex was added, followed by the addition of bis(trimethylsiloxymethylsilane) at a rate of 1 drop / 2 s. After reacting at 90 °C for 7 h, the catalyst was adsorbed with activated carbon, and the solvent and unreacted bis(trimethylsiloxymethylsilane) were removed by rotary evaporation. The crude product was purified by column chromatography (V 石油醚 V 二氯甲烷 =4:1), yielding the auxiliary agent (yield 85%); the NMR and mass spectrometry results of the auxiliary agent are as follows: 1 HNMR: (C 54 H 92 O 10 N4Si7, 400MHz, DMSO- d6) δ: 0.14 (s, 6H), 0.21 (s, 36H), 1.5 (s, 2H), 1.61-1.65 (m, 2H), 2.31-2.35 (m, 2H), 2.51-2.60 (m, 6H), 2.73-2.77 (t, 4H), 3.29-3.33 (m, 2H) , 3.54-3.58 (m, 2H), 3.70 (s, 4H), 3.83 (s, 6H), 4.24 (s, 2H), 5.01 (s, 4H), 6.73 (s, 2H), 6.91 (s, 2H), 7.35-7.39 (m, 6H), 7.44-7.48 (m, 4H). MS (ESI) m / z=1152.52 [M].

[0031] Preparation Example 2 The preparation process of the additive is as follows: (1) Using an ethylenediamine to acetone ratio of 0.2 mol: 200 mL, ethylenediamine was dissolved in acetone, and a 2.5 mol / L solution of dichlorodiphenylsilane in acetone was added dropwise at 0 °C, wherein the ratio of dichlorodiphenylsilane to ethylenediamine was 0.05 mol: 0.18 mol. After the addition was complete, the mixture was reacted at 25 °C for 14 h. The mixture was filtered to remove impurities, and acetone and excess ethylenediamine were removed by vacuum distillation. The residue was purified by column chromatography (V 乙酸乙酯 V 石油醚 =3:1, with the addition of 1% by volume of triethylamine), to obtain intermediate 1 (yield 78%); the NMR and mass spectrometry results of intermediate 1 were consistent with those of preparation example 1.

[0032] (2) Using intermediate 1, coniferol, paraformaldehyde, triethylamine, and mixed solvent in a ratio of 0.02 mol: 0.04 mol: 0.08 mol: 0.04 mol: 80 mL, intermediate 1, triethylamine, and paraformaldehyde were added to a mixed solvent (composed of ethanol and toluene in a volume ratio of 2:1). After mixing thoroughly, coniferol was added, and the mixture was stirred at 70 °C for 45 min. Then, the mixture was heated to 90 °C and the reaction was continued for 8 h. After the reaction was completed, the mixture was cooled to room temperature and extracted with ethyl acetate and 1 mol / L NaOH aqueous solution. The organic phase was washed with deionized water, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified by column chromatography (V 乙酸乙酯 V 石油醚 =2:1, add 1% volume of triethylamine), to obtain intermediate 2 (yield 77%); the NMR and mass spectrometry results of intermediate 2 are consistent with those of preparation example 1.

[0033] (3) Intermediate 2, bis(trimethylsiloxymethylsilane), and toluene were mixed in a ratio of 0.5 mmol:1.1 mmol:80 mL. Intermediate 2 was dissolved in toluene, and the mixture was heated to 70 °C under nitrogen protection. 0.05 wt% of platinum(O)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex was added, followed by the addition of bis(trimethylsiloxymethylsilane) at a rate of 1 drop / 2 s. After reacting at 80 °C for 8 h, the catalyst was adsorbed with activated carbon, and the solvent and unreacted bis(trimethylsiloxymethylsilane) were removed by rotary evaporation. The crude product was purified by column chromatography (V 石油醚 V 二氯甲烷 =4:1), and the auxiliary agent was obtained (yield 82%); the NMR and mass spectrometry results of the auxiliary agent were consistent with those of Preparation Example 1.

[0034] Preparation Example 3 The preparation process of the additive is as follows: (1) Using an ethylenediamine to acetone ratio of 0.2 mol: 220 mL, ethylenediamine was dissolved in acetone, and a 2.5 mol / L solution of dichlorodiphenylsilane in acetone was added dropwise at 5 °C, wherein the ratio of dichlorodiphenylsilane to ethylenediamine was 0.05 mol: 0.2 mol. After the addition was complete, the mixture was reacted at 20 °C for 16 h. The mixture was filtered to remove impurities, and acetone and excess ethylenediamine were removed by vacuum distillation. The residue was purified by column chromatography (V 乙酸乙酯 V 石油醚 =3:1, with the addition of 1% by volume of triethylamine), to obtain intermediate 1 (yield 76%); the NMR and mass spectrometry results of intermediate 1 were consistent with those of preparation example 1.

[0035] (2) Using intermediate 1, coniferol, paraformaldehyde, triethylamine, and mixed solvent in a ratio of 0.02 mol: 0.042 mol: 0.084 mol: 0.042 mol: 100 mL, intermediate 1, triethylamine, and paraformaldehyde were added to a mixed solvent (composed of ethanol and toluene in a volume ratio of 2:1). After mixing thoroughly, coniferol was added, and the mixture was stirred at 75 °C for 30 min. Then, the mixture was heated to 95 °C and the reaction was continued for 5 h. After the reaction was completed, the mixture was cooled to room temperature and extracted with ethyl acetate and 1 mol / L NaOH aqueous solution. The organic phase was washed with deionized water, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified by column chromatography (V 乙酸乙酯 V 石油醚 =2:1, with the addition of 1% by volume of triethylamine), to obtain intermediate 2 (yield 76%); the NMR and mass spectrometry results of intermediate 2 are consistent with those of preparation example 1.

[0036] (3) Intermediate 2, bis(trimethylsiloxymethylsilane), and toluene were used in a ratio of 0.5 mmol: 1.3 mmol: 100 mL. Intermediate 2 was dissolved in toluene, and the mixture was heated to 80 °C under nitrogen protection. 0.1 wt% of platinum(O)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex was added, followed by the addition of bis(trimethylsiloxymethylsilane) at a rate of 1 drop / 2 s. After reacting at 100 °C for 6 h, the catalyst was adsorbed with activated carbon, and the solvent and unreacted bis(trimethylsiloxymethylsilane) were removed by rotary evaporation. The crude product was purified by column chromatography (V 石油醚 V 二氯甲烷 =4:1), to obtain the auxiliary agent (yield 80%); the NMR and mass spectrometry results of the auxiliary agent were consistent with those of Preparation Example 1.

[0037] Preparation Example 4 The preparation process of modified montmorillonite is as follows: (a) Using montmorillonite, 3-chloropropyltrimethoxysilane, and methanol aqueous solution in a ratio of 1 g: 0.6 g: 80 mL, 3-chloropropyltrimethoxysilane was added to an 85% (v / v) methanol aqueous solution, the pH was adjusted to 5.3 with glacial acetic acid, and the mixture was stirred at 62 °C for 1.5 h. Montmorillonite was then added, and the reaction was continued for 6 h. After the reaction was completed, the mixture was filtered, washed with methanol, and dried under vacuum to obtain pretreated montmorillonite. Using pretreated montmorillonite, 5-aminophenyl-1,3-dicarboxynitrile, triethylamine, and DMF in a ratio of 1 g: 0.9 g: 0.7 mL: 70 mL, pretreated montmorillonite was ultrasonically dispersed in N,N-dimethylformamide (DMF), 5-aminophenyl-1,3-dicarboxynitrile and triethylamine were added, and the mixture was reacted at 82 °C for 9 h. After the reaction was completed, the mixture was filtered, washed successively with anhydrous ethanol and deionized water, and dried under vacuum to obtain cyano-modified montmorillonite. (b) Using cyano-modified montmorillonite, 2-aminopyridine, cuprous bromide, 1,10-phenanthroline, zinc iodide, and 1,2-dichlorobenzene in a ratio of 1 g: 0.7 g: 0.04 g: 0.05 g: 0.2 g: 18 mL, cyano-modified montmorillonite was ultrasonically dispersed in 1,2-dichlorobenzene. 2-aminopyridine, cuprous bromide, 1,10-phenanthroline (CAS: 66-71-7) and zinc iodide were added. The mixture was heated to 133 °C under sealed conditions and stirred for 30 h. After cooling to room temperature, the mixture was filtered, washed successively with ethanol and deionized water, and dried under vacuum to obtain modified montmorillonite.

[0038] Preparation Example 5 The preparation process of modified montmorillonite is as follows: (a) Using montmorillonite, 3-chloropropyltrimethoxysilane, and methanol aqueous solution in a ratio of 1 g: 0.4 g: 70 mL, 3-chloropropyltrimethoxysilane was added to an 85% (v / v) methanol aqueous solution, the pH was adjusted to 5 with glacial acetic acid, and the mixture was stirred at 60 °C for 2 h. Montmorillonite was then added, and the reaction was continued for 8 h. After the reaction was completed, the mixture was filtered, washed with methanol, and dried under vacuum to obtain pretreated montmorillonite. Using pretreated montmorillonite, 5-aminophenyl-1,3-dicarboxynitrile, triethylamine, and DMF in a ratio of 1 g: 0.6 g: 0.5 mL: 60 mL, pretreated montmorillonite was ultrasonically dispersed in DMF, 5-aminophenyl-1,3-dicarboxynitrile and triethylamine were added, and the mixture was reacted at 80 °C for 10 h. After the reaction was completed, the mixture was filtered, washed successively with anhydrous ethanol and deionized water, and dried under vacuum to obtain cyano-modified montmorillonite. (b) Using cyano-modified montmorillonite, 2-aminopyridine, cuprous bromide, 1,10-phenanthroline, zinc iodide, and 1,2-dichlorobenzene in a ratio of 1 g: 0.45 g: 0.03 g: 0.036 g: 0.13 g: 15 mL, cyano-modified montmorillonite was ultrasonically dispersed in 1,2-dichlorobenzene. Then, 2-aminopyridine, cuprous bromide, 1,10-phenanthroline, and zinc iodide were added. The mixture was heated to 130 °C under sealed conditions and stirred for 36 h. After cooling to room temperature, the mixture was filtered, washed successively with ethanol and deionized water, and dried under vacuum to obtain modified montmorillonite.

[0039] Preparation Example 6 The preparation process of modified montmorillonite is as follows: (a) Using montmorillonite, 3-chloropropyltrimethoxysilane, and methanol aqueous solution in a ratio of 1 g: 0.8 g: 90 mL, 3-chloropropyltrimethoxysilane was added to an 85% (v / v) methanol aqueous solution, the pH was adjusted to 5.5 with glacial acetic acid, and the mixture was stirred at 65 °C for 1 h. Montmorillonite was then added, and the reaction was continued for 4 h. After the reaction was completed, the mixture was filtered, washed with methanol, and dried under vacuum to obtain pretreated montmorillonite. Using pretreated montmorillonite, 5-aminophenyl-1,3-dicarboxynitrile, triethylamine, and DMF in a ratio of 1 g: 1.2 g: 1 mL: 80 mL, pretreated montmorillonite was ultrasonically dispersed in DMF, 5-aminophenyl-1,3-dicarboxynitrile and triethylamine were added, and the mixture was reacted at 85 °C for 7 h. After the reaction was completed, the mixture was filtered, washed successively with anhydrous ethanol and deionized water, and dried under vacuum to obtain cyano-modified montmorillonite. (b) Using cyano-modified montmorillonite, 2-aminopyridine, cuprous bromide, 1,10-phenanthroline, zinc iodide, and 1,2-dichlorobenzene in a ratio of 1 g: 0.9 g: 0.06 g: 0.072 g: 0.26 g: 20 mL, cyano-modified montmorillonite was ultrasonically dispersed in 1,2-dichlorobenzene. Then, 2-aminopyridine, cuprous bromide, 1,10-phenanthroline, and zinc iodide were added. The mixture was heated to 135 °C under sealed conditions and stirred for 24 h. After cooling to room temperature, the mixture was filtered, washed successively with ethanol and deionized water, and dried under vacuum to obtain modified montmorillonite.

[0040] Example 1 A waterproof and corrosion-resistant polyvinyl chloride composite membrane includes a substrate layer and a PVC protective layer; the PVC protective layer is coated on the surface of the substrate layer; by weight, the PVC protective layer includes the following raw materials: 62 parts of polyvinyl chloride paste resin, 30 parts of dioctyl terephthalate, 7 parts of modified montmorillonite of Preparation Example 4, 9 parts of additives of Preparation Example 1, and 3 parts of calcium-zinc composite stabilizer; the substrate layer is made of nylon fiber cloth.

[0041] The preparation method of the above-mentioned waterproof and corrosion-resistant polyvinyl chloride composite membrane includes the following steps: The nylon fiber cloth was corona treated to obtain a substrate layer; polyvinyl chloride paste resin, dioctyl terephthalate, modified montmorillonite, additives and calcium-zinc composite stabilizer were mixed, stirred evenly and then coated onto the surface of the substrate layer to obtain a 0.1 mm PVC protective layer, which was then plasticized at 162℃ for 18 min to obtain the final product.

[0042] Example 2 A waterproof and corrosion-resistant polyvinyl chloride composite membrane includes a substrate layer and a PVC protective layer; the PVC protective layer is coated on the surface of the substrate layer; by weight, the PVC protective layer includes the following raw materials: 50 parts of polyvinyl chloride paste resin, 20 parts of epoxidized soybean oil, 5 parts of modified montmorillonite of Preparation Example 5, 5 parts of additives of Preparation Example 2, and 1 part of calcium-zinc composite stabilizer; the substrate layer is made of nylon fiber cloth.

[0043] The preparation method of the above-mentioned waterproof and corrosion-resistant polyvinyl chloride composite membrane includes the following steps: The nylon fiber cloth was corona treated to obtain a substrate layer; polyvinyl chloride paste resin, epoxidized soybean oil, modified montmorillonite, additives and calcium-zinc composite stabilizer were mixed, stirred evenly and then coated onto the surface of the substrate layer to obtain a 0.06 mm PVC protective layer, which was then plasticized at 160℃ for 20 min to obtain the final product.

[0044] Example 3 A waterproof and corrosion-resistant polyvinyl chloride composite membrane includes a substrate layer and a PVC protective layer; the PVC protective layer is coated on the surface of the substrate layer; by weight, the PVC protective layer includes the following raw materials: 70 parts of polyvinyl chloride paste resin, 40 parts of diisononyl phthalate, 10 parts of modified montmorillonite of Preparation Example 6, 15 parts of additives of Preparation Example 3, and 5 parts of calcium-zinc composite stabilizer; the substrate layer is made of nylon fiber cloth.

[0045] The preparation method of the above-mentioned waterproof and corrosion-resistant polyvinyl chloride composite membrane includes the following steps: The nylon fiber cloth is subjected to corona treatment to obtain a substrate layer; polyvinyl chloride paste resin, diisononyl phthalate, modified montmorillonite, additives and calcium-zinc composite stabilizer are mixed, stirred evenly and then coated onto the surface of the substrate layer to obtain a 0.15mm PVC protective layer, which is then plasticized at 165℃ for 15 minutes to obtain the final product.

[0046] Comparative Example 1 The difference between this comparative example and Example 1 is that the modified montmorillonite in Preparation Example 4 is replaced with montmorillonite.

[0047] Comparative Example 2 The difference between this comparative example and Example 1 is that the additives used in Example 1 are omitted.

[0048] Experimental Example 1 The modified montmorillonite from Preparation Example 4 was characterized by scanning electron microscopy (SEM). The microstructure results are as follows: Figure 1 As shown.

[0049] Figure 1 This is a SEM image of the modified montmorillonite prepared in Example 4. (Observation) Figure 1 It can be seen that after 3-chloropropyltrimethoxysilane silanization pretreatment, followed by cyano grafting and construction of triazolidine nitrogen-containing heterocycles, montmorillonite exhibits good lamellae exfoliation, uniform dispersion, and increased interlamellae spacing.

[0050] Experimental Example 2 The performance of the composite membranes obtained in the examples or comparative examples was tested, as follows: Limiting Oxygen Index (LOI): Tested according to GB / T 2406.1-2008; Water contact angle: Tested according to GB / T 30693-2014; Salt water resistance: The salt water resistance was determined according to Method B (heated salt water resistance method) of GB / T 1763-1979 (1989) "Determination of Chemical Reagent Resistance of Coatings". The experimental conditions were: 5wt% NaCl solution, soaking time 60 days. After 60 days, the wrinkling, blistering, and peeling of the PVC protective layer were observed and recorded. Alkali resistance: The method for determining acid and alkali resistance was performed according to GB / T 1763-1979 (1989) "Determination of Chemical Resistance of Coatings". The experimental conditions were: 10wt% NaOH solution, soaking time 110 h. After 110 h, the wrinkling, blistering, and peeling of the PVC protective layer were observed and recorded. Acid resistance: The method for determining acid and alkali resistance was performed according to GB / T 1763-1979 (1989) "Determination of Chemical Resistance of Coatings". The experimental conditions were: 10wt% H2SO4 solution, immersion time 110 h. After 110 h, the wrinkling, blistering, and peeling of the PVC protective layer were observed and recorded. The test results for the above performance are shown in Table 1.

[0051] Table 1 As shown in Table 1, in terms of flame retardant performance, the limiting oxygen index of Examples 1-3 is all above 34%, which is significantly higher than that of Comparative Example 2. This indicates that the benzoxazine and silane structures in the additives of this invention can effectively improve the flame retardant performance of PVC composite films.

[0052] Regarding waterproof performance: the water contact angles of Examples 1-3 were all greater than 125°, exhibiting a distinct hydrophobic state. The water contact angle of Comparative Example 1 was 98.5°, while that of Comparative Example 2 was only 85.3°. This indicates that the heptamethyltrisiloxane hydrophobic segment in the additive synergistically enhances the waterproof performance of the composite membrane with the low surface energy structure of benzoxazine.

[0053] Regarding corrosion resistance: Examples 1-3 and Comparative Example 2 showed no changes in acid, alkali, and salt solutions, while Comparative Example 1 exhibited large-area blistering and small-area peeling. This indicates that modified montmorillonite is the key component that imparts excellent corrosion resistance to the composite film; while Comparative Example 1 (montmorillonite) was not modified with heterocyclic compounds and could not resist the erosion of acid and alkali media.

[0054] Experimental Example 3 The composite membranes prepared in the examples or comparative examples were subjected to high temperature resistance tests. They were placed in water at different temperatures of 70°C, 80°C, 90°C, 100°C, and 110°C and heated for 30 minutes. The deformation of each group of samples was observed. The results are shown in Table 2.

[0055] Table 2 Table 2 shows that Examples 1-3 and Comparative Example 2 did not deform in water at 70-100℃, only showing slight deformation at 110℃. Comparative Example 1, however, showed slight deformation at 90℃ and significant deformation at 100℃ and 110℃. This indicates that the composite membrane using the modified montmorillonite of this invention has excellent thermal stability and can withstand hot water environments below 100℃. In contrast, Comparative Example 1, using montmorillonite, suffers from poor compatibility between the sheets and the PVC matrix, leading to a significant decrease in the heat distortion temperature of the composite membrane.

[0056] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A waterproof and corrosion-resistant polyvinyl chloride composite membrane, characterized in that, It includes a substrate layer and a PVC protective layer; the PVC protective layer is coated on the surface of the substrate layer; by weight, the PVC protective layer includes the following raw materials: 50-70 parts of polyvinyl chloride, 20-40 parts of plasticizer, 5-10 parts of modified montmorillonite, 5-15 parts of additives, and 1-5 parts of heat stabilizer. The structural formula of the auxiliary agent is: 。 2. The waterproof and corrosion-resistant polyvinyl chloride composite membrane according to claim 1, characterized in that, The preparation process of the auxiliary agent is as follows: (1) Add ethylenediamine to acetone, then add an acetone solution of dichlorodiphenylsilane, and purify after reaction to obtain intermediate 1; The structural formula of intermediate 1 is: (2) Add intermediate 1, triethylamine and paraformaldehyde to a mixed solvent, then add conifer alcohol, stir to react, heat and continue to react, and purify after reaction to obtain intermediate 2. The structural formula of intermediate 2 is as follows: (3) The intermediate 2 is added to toluene, and then a catalyst and bistrimethylsiloxymethylsilane are added. After the reaction, the mixture is purified to obtain the auxiliary agent.

3. The waterproof and corrosion-resistant polyvinyl chloride composite membrane according to claim 2, characterized in that, In step (1), the molar ratio of dichlorodiphenylsilane to ethylenediamine is 1:(3.6-4); the concentration of the acetone solution of dichlorodiphenylsilane is 2.5 mol / L, and the temperature at which it is added is 0-5℃; the ratio of ethylenediamine to acetone is 1 mol:(1-1.1) L; the reaction temperature is 20-25℃, and the reaction time is 14-16 h; in step (2), the molar ratio of intermediate 1, coniferyl alcohol, paraformaldehyde, and triethylamine is 1:(2-2.1):(4-4.2):(2-2.1); the mixed solvent is composed of ethanol and toluene in a volume ratio of 2:1; the stirring reaction temperature is 70-75℃, and the reaction time is 30-45 min; the reaction is continued at 90-95℃ for 5-8 h.

4. The waterproof and corrosion-resistant polyvinyl chloride composite membrane according to claim 2, characterized in that, In step (3), the molar ratio of intermediate 2 and bis(trimethylsiloxymethylsilane) is 1:(2.2-2.6); the amount of catalyst added is 0.05-0.1 wt% of the total mass of the reactants; the catalyst is a platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, and the temperature at which it is added is 70-80℃; the reaction temperature is 80-100℃ and the time is 6-8h.

5. The waterproof and corrosion-resistant polyvinyl chloride composite membrane according to claim 1, characterized in that, The preparation process of the modified montmorillonite is as follows: (a) Pretreated montmorillonite was added to N,N-dimethylformamide, followed by the addition of 5-aminophenyl-1,3-dicarboxynitrile and triethylamine. After reaction, the mixture was purified to obtain cyano-modified montmorillonite. (b) The cyano-modified montmorillonite was added to 1,2-dichlorobenzene, followed by the addition of 2-aminopyridine, cuprous bromide, 1,10-phenanthroline and zinc iodide. After stirring and reacting, the mixture was purified to obtain the modified montmorillonite.

6. The waterproof and corrosion-resistant polyvinyl chloride composite membrane according to claim 5, characterized in that, In step (a), the ratio of pretreated montmorillonite, 5-aminophenyl-1,3-dicarboxynitrile, and triethylamine is 1 g : (0.6-1.2) g : (0.5-1) mL; the reaction temperature is 80-85℃ and the reaction time is 7-10 h; in step (b), the mass ratio of cyano-modified montmorillonite, 2-aminopyridine, cuprous bromide, 1,10-phenanthroline, and zinc iodide is 1 : (0.45-0.9) : (0.03-0.06) : (0.036-0.072) : (0.13-0.26); the stirring reaction temperature is 130-135℃ and the reaction time is 24-36 h.

7. The waterproof and corrosion-resistant polyvinyl chloride composite membrane according to claim 6, characterized in that, The preparation process of the pretreated montmorillonite is as follows: 3-Chloropropyltrimethoxysilane was added to an aqueous methanol solution, the pH was adjusted, the reaction was stirred, montmorillonite was added, the reaction was continued, and then purified to obtain the pretreated montmorillonite.

8. The waterproof and corrosion-resistant polyvinyl chloride composite membrane according to claim 7, characterized in that, The mass ratio of montmorillonite to 3-chloropropyltrimethoxysilane is 1:(0.4-0.8); the pH is adjusted to 5-5.5; the stirring reaction temperature is 60-65℃ for 1-2 hours; the reaction continues for 4-8 hours; and the volume fraction of the methanol aqueous solution is 85%.

9. The waterproof and corrosion-resistant polyvinyl chloride composite membrane according to claim 1, characterized in that, The polyvinyl chloride is polyvinyl chloride paste resin; the heat stabilizer is a calcium-zinc composite stabilizer; the plasticizer is selected from one of dioctyl terephthalate, epoxidized soybean oil, and diisononyl phthalate; the substrate layer is made of nylon fiber cloth.

10. A method for preparing a waterproof and corrosion-resistant polyvinyl chloride composite membrane according to any one of claims 1-9, characterized in that, Includes the following steps: Polyvinyl chloride, plasticizer, modified montmorillonite, additives and heat stabilizer are mixed evenly and then coated on the surface of the substrate layer to obtain a PVC protective layer. After plasticizing, the product is obtained.

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