Polyvinyl chloride supercritical gas co-foamed plate and preparation process thereof

Abstract

The application relates to the technical field of high polymer composite materials, and discloses a polyvinyl chloride supercritical gas co-foaming plate and a preparation process thereof. The polyvinyl chloride supercritical gas co-foaming plate comprises the following raw materials in parts by weight: 100 parts of polyvinyl chloride resin, 40-60 parts of a flame-retardant plasticizer, 5-15 parts of nano calcium carbonate, 2-5 parts of epoxy soybean oil, 3-6 parts of a calcium-zinc stabilizer, 0.2-0.5 parts of polyethylene wax and 0.2-0.6 parts of oxidized polyethylene wax. The raw materials are mixed to obtain a pressing material, then carbon dioxide gas is introduced into the pressing material, and the polyvinyl chloride supercritical gas co-foaming plate is obtained under a supercritical process. The polyvinyl chloride supercritical gas co-foaming plate prepared by the application has excellent flame-retardant performance, antibacterial performance, migration resistance and mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, specifically to a polyvinyl chloride supercritical gas co-foaming board and its preparation process. Background Technology

[0002] Polyvinyl chloride (PVC) foam boards are widely used in building decoration, transportation, and packaging due to their lightweight, heat insulation, and sound insulation properties. However, traditional PVC foam materials suffer from poor flame retardancy and insufficient mechanical strength. Conventional foaming processes often use chemical foaming agents (such as AC foaming agents), which easily leave decomposition products, and the introduced byproducts may cause toxicity, affecting environmental performance and product stability. Supercritical carbon dioxide, as a foaming agent, can replace traditional chemical foaming agents. Its supercritical physical foaming method has gradually become the focus of the industry due to its advantages such as being environmentally friendly and non-toxic, and allowing for the recycling of foaming agents. It can produce lower-density polymer foam materials to meet people's needs.

[0003] Furthermore, common plasticizers (such as phthalates) are prone to migration and have insufficient flame retardant properties, making it difficult to meet application requirements. For example, patent application publication number CN104194374A discloses a micro-foamed wood-plastic composite board. This invention uses modified wood flour, polyvinyl chloride, methyl methacrylate-butadiene-styrene terpolymer, chlorinated polyethylene, activated carbon, azodicarbonamide, dioctyl phthalate, aminosilane coupling agent, calcium stearate, and other raw materials to prepare a foamed wood-plastic composite board with properties such as low brittleness, strong impact resistance, and good sound insulation, but it does not improve the flame retardant, migration resistance, and antibacterial properties of the board. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a supercritical gas co-foamed polyvinyl chloride board and its preparation process. The prepared foamed board, in addition to having excellent flame retardant properties, also has excellent antibacterial properties, migration resistance, and mechanical properties.

[0006] (II) Technical Solution

[0007] A supercritical gas co-foamed polyvinyl chloride board and its preparation process include the following steps:

[0008] Step 1: Prepare the following parts by weight: 100 parts polyvinyl chloride resin, 40-60 parts flame retardant plasticizer, 5-15 parts nano calcium carbonate, 2-5 parts epoxidized soybean oil, 3-6 parts calcium-zinc stabilizer, 0.2-0.5 parts polyethylene wax, and 0.2-0.6 parts oxidized polyethylene wax.

[0009] The second step involves mixing polyvinyl chloride resin, flame-retardant plasticizer, nano-calcium carbonate, epoxidized soybean oil, calcium-zinc stabilizer, polyethylene wax, and oxidized polyethylene wax at a mixing temperature of 180-190℃ and a rotation speed of 40-60 r / min. Then, the mixture is pressed at 190-200℃ for 8-15 minutes at a pressing pressure of 8-12 MPa to obtain the pressed material.

[0010] The third step is to place the obtained pressed material in a high-pressure reactor, introduce carbon dioxide gas, exhaust the gas 2-4 times, maintain the temperature inside the reactor at 75-85℃ for 2-4 hours, and maintain the pressure at 8-10MPa. Then, open the exhaust valve on the high-pressure reactor to reduce the pressure to atmospheric pressure, and introduce cooling water into the cooling system of the reactor to obtain polyvinyl chloride supercritical gas co-foamed board.

[0011] Preferably, the preparation method of the flame-retardant plasticizer includes the following steps:

[0012] S1. Add monooctyl phthalate, thionyl chloride and catalyst to a flask and stir. At 115-125℃ for 9-12 h, collect the gas, distill, and distill under reduced pressure to obtain the acyl chloride product. Pour 10-chloro-1-decyl alcohol into the flask, add the obtained acyl chloride product and dichloromethane solvent, and stir at 10-20℃ for 3-5 h. After the reaction is completed, wash with deionized water, dry, filter and rotary evaporate, and finally distill under reduced pressure to obtain intermediate product 1.

[0013] S2. Add intermediate product 1 and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane to n-butanol solvent, stir evenly, heat to 72-80℃, react for 20-30h, rotary evaporate after reaction, wash with deionized water, dry to obtain intermediate product 2.

[0014] S3. Mix nano-bismuth oxychloride with 92-98wt% ethanol solution, heat at 55-65℃ for 15-30 min, then add intermediate product 2, stir at 55-65℃ for 4-8 h, vacuum dry, filter, and obtain flame retardant plasticizer.

[0015] Preferably, the catalyst comprises one or more of 1-methylpyrrolidine, 1-methylpiperidine, 1-ethylpiperidine, and 3-methylpyridine.

[0016] Preferably, in S1, the ratio of monooctyl phthalate, thionyl chloride, catalyst, and 10-chloro-1-decyl alcohol is (80-84)g:150g:1g:114-130g.

[0017] Preferably, in S2, the ratio of intermediate product 1 to 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane is (1.1-1.3) g:1 g.

[0018] Preferably, in step S3, the ratio of intermediate product 2 to nano-bismuth oxychloride is (2.4-2.8) g:1 g.

[0019] Preferably, the method for preparing the nano-bismuth oxychloride includes the following steps:

[0020] Bismuth nitrate pentahydrate, potassium chloride, and deionized water were mixed and sonicated for 10-20 min, then stirred at room temperature for 30-50 min. A 0.8-1.2 mol / L sodium hydroxide solution was then added to adjust the pH to 5.5-6.5. The mixture was stirred at room temperature for 3-5 h, then reacted in an autoclave at 175-185℃ for 8-12 h. After cooling, the mixture was washed 2-3 times each with deionized water and anhydrous ethanol, filtered, and a filter cake was obtained. The filter cake was added to an autoclave, and carbon dioxide gas was introduced. The mixture was vented 2-3 times, and the autoclave was maintained at 15-20℃ for 2-3 h at a pressure of 5-6 MPa. The mixture was then subjected to supercritical drying, cooled to atmospheric pressure, and nano-bismuth oxychloride was obtained.

[0021] Preferably, the ratio of bismuth nitrate pentahydrate to potassium chloride is (6-6.5) g: 1 g.

[0022] Preferred conditions for supercritical drying are: maintaining at 35-45℃ for 1-2 hours and a pressure of 7-8 MPa.

[0023] (iii) Beneficial technical effects

[0024] 1. Reaction Mechanism of the Invention: The present invention uses monooctyl phthalate, thionyl chloride, and a catalyst as raw materials, which undergo acyl chloride to obtain an acyl chloride product. Then, 10-chloro-1-decyl alcohol and the obtained acyl chloride product undergo esterification to obtain intermediate product 1. Intermediate product 1 and a tertiary amine contained in 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane undergo quaternization to obtain intermediate product 2. The silanol obtained after hydrolysis of intermediate product 2 reacts with the hydroxyl groups on the surface of nano-bismuth oxychloride to obtain a flame-retardant plasticizer. Polyvinyl chloride resin, flame-retardant plasticizer, nano-calcium carbonate, epoxidized soybean oil, calcium-zinc stabilizer, polyethylene wax, and oxidized polyethylene wax are used as raw materials for compounding to obtain a pressed material. Then, carbon dioxide gas is introduced into the pressed material, and under supercritical conditions, a supercritical gas co-foamed polyvinyl chloride board is obtained.

[0025] 2. In the process of synthesizing intermediate product 1 in this invention, monooctyl phthalate is acylchlorinated and then esterified with 10-chloro-1-decyl alcohol. The reaction conditions are mild, with few byproducts. The chlorine atom is precisely placed at the end of the long chain, and the chlorine atom at the end of the long chain has little steric hindrance, making it easy to undergo nucleophilic substitution (SN2).

[0026] 3. In the flame-retardant plasticizer prepared in this invention, 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane has a unique bifunctional structure. One branch of dioctyl phthalate retains the plasticizing effect, while the other branch establishes a chemical bond bridge with nano-bismuth oxychloride. On the one hand, nano-bismuth oxychloride, an inorganic material with good mechanical and flame-retardant properties, is selected to bond with its surface hydroxyl groups, preventing the nano-bismuth oxychloride particles from agglomerating and improving its dispersibility in polyvinyl chloride. On the other hand, dioctyl phthalate, which is low in cost, is selected to bond with its terminal chlorine atoms to form a long-chain terminal quaternary ammonium salt, resulting in good antibacterial properties. In addition, the hydroxyl groups of 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane form hydrogen bonds with the polar groups of the polyvinyl chloride molecular chain, reducing phase separation and improving mechanical properties. The plasticizer is anchored to the surface of bismuth oxychloride nanoparticles through chemical bonding, exhibiting migration resistance. Attached Figure Description

[0027] Figure 1 This is the reaction route for intermediate product 1;

[0028] Figure 2 This is the reaction route for intermediate product 2. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1: A method for preparing nano-bismuth oxychloride according to this example includes the following steps:

[0031] Mix 12g of bismuth nitrate pentahydrate, 2g of potassium chloride, and 250mL of deionized water, sonicate for 10min, stir at 25℃ for 30min, then add 0.8-1.2mol / L sodium hydroxide solution to adjust the pH to 5.5-6.5, stir at 25℃ for 3-5h, then react in an autoclave at 175-185℃ for 8-12h, cool, wash 2-3 times each with deionized water and anhydrous ethanol, filter to obtain a filter cake, add the filter cake to an autoclave, introduce carbon dioxide gas, exhaust 2-3 times, maintain the autoclave at 15-20℃ for 2-3h at 5-6MPa, supercritical drying, maintain at 35-45℃ for 1-2h at 7-8MPa, at atmospheric pressure, cool to obtain nano-bismuth oxychloride.

[0032] The preparation method of a flame-retardant plasticizer according to this embodiment includes the following steps:

[0033] S1. Add 40g of monooctyl phthalate, 75g of thionyl chloride and 0.5g of 1-methylpyrrolidine to a flask and stir. Heat at 115℃ for 9h, collect the gas, distill, and distill under reduced pressure to obtain the acyl chloride product. Add 57g of 10-chloro-1-decyl alcohol to the flask, then add the obtained acyl chloride product and 400mL of dichloromethane solvent. Heat at 10℃ for 3h. After the reaction is complete, wash with deionized water, dry, filter and rotary evaporate, and finally distill under reduced pressure to obtain intermediate product 1.

[0034] S2. Add 2.2-g of intermediate product 1 and 2g of 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane to n-butanol solvent, stir evenly, heat to 72℃, react for 20h, after the reaction is completed, rotary evaporate, wash with deionized water, dry to obtain intermediate product 2.

[0035] S3. Mix 3g of nano-bismuth oxychloride with 40mL of 92wt% ethanol solution, heat at 55℃ for 15min, then add 7.2g of intermediate product 2, stir at 55℃ for 4h, vacuum dry, filter, and obtain flame-retardant plasticizer.

[0036] This embodiment describes a polyvinyl chloride supercritical gas co-foamed board and its preparation process, which includes the following steps:

[0037] Step 1: Mix 50g of polyvinyl chloride resin, 20g of flame-retardant plasticizer, 2.5g of nano-calcium carbonate, 1g of epoxidized soybean oil, 1.5g of calcium-zinc stabilizer, 0.1g of polyethylene wax and 0.1g of oxidized polyethylene wax at a mixing temperature of 180℃ and a rotation speed of 40r / min. Then press the mixture at 190℃ for 8-15 minutes at a pressing pressure of 8MPa to obtain the pressed material.

[0038] The second step involves placing the obtained pressed material in a high-pressure reactor, introducing carbon dioxide gas, venting twice, maintaining the reactor at 75°C for 2 hours, and a pressure of 8 MPa. Then, the exhaust valve on the high-pressure reactor is opened to reduce the pressure to atmospheric pressure, and cooling water is introduced into the cooling system of the reactor to obtain polyvinyl chloride supercritical gas co-foamed board.

[0039] Example 2, a method for preparing nano-bismuth oxychloride in this example, includes the following steps:

[0040] 13g of bismuth nitrate pentahydrate, 2g of potassium chloride, and 250mL of deionized water were mixed and sonicated for 20min. The mixture was then stirred at 25℃ for 50min. A 1.2mol / L sodium hydroxide solution was added to adjust the pH to 6.5. The mixture was stirred at 25℃ for 5h and then reacted in an autoclave at 185℃ for 12h. After cooling, the mixture was washed three times each with deionized water and anhydrous ethanol. The mixture was filtered to obtain a filter cake. The filter cake was added to an autoclave, and carbon dioxide gas was introduced. The mixture was vented three times. The autoclave was kept at 20℃ for 3h and a pressure of 6MPa for supercritical drying. The mixture was kept at 45℃ for 2h and a pressure of 8MPa for atmospheric pressure. After cooling, nano-bismuth oxychloride was obtained.

[0041] The preparation method of a flame-retardant plasticizer according to this embodiment includes the following steps:

[0042] S1. Add 442g of monooctyl phthalate, 75g of thionyl chloride and 0.5g of 1-methylpyrrolidine to a flask and stir. Stir at 125℃ for 12h, collect the gas, distill, and distill under reduced pressure to obtain the acyl chloride product. Add 65g of 10-chloro-1-decyl alcohol to the flask, then add the obtained acyl chloride product and 400mL of dichloromethane solvent. Stir at 20℃ for 5h. After the reaction is complete, wash with deionized water, dry, filter and rotary evaporate, and finally distill under reduced pressure to obtain intermediate product 1.

[0043] S2. Add 2.6g of intermediate product 1 and 2g of 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane to n-butanol solvent, stir evenly, heat to 80℃, react for 30h, after the reaction is completed, rotary evaporate, wash with deionized water, dry to obtain intermediate product 2.

[0044] S3. Mix 3g of nano-bismuth oxychloride with 40mL of 98wt% ethanol solution, heat at 65℃ for 30min, then add 8.4g of intermediate product 2, stir at 55-65℃ for 4-8h, vacuum dry, filter, and obtain flame-retardant plasticizer.

[0045] This embodiment describes a polyvinyl chloride supercritical gas co-foamed board and its preparation process, which includes the following steps:

[0046] Step 1: Mix 50g of polyvinyl chloride resin, 30g of flame-retardant plasticizer, 7.5g of nano-calcium carbonate, 2.5g of epoxidized soybean oil, 3g of calcium-zinc stabilizer, 0.25g of polyethylene wax and 0.3g of oxidized polyethylene wax at a mixing temperature of 190℃ and a rotation speed of 60r / min. Then press the mixture at 200℃ for 15min at a pressing pressure of 12MPa to obtain the pressed material.

[0047] The second step involves placing the obtained pressed material in a high-pressure reactor, introducing carbon dioxide gas, venting the reactor four times, maintaining the reactor at 85°C for 4 hours, and a pressure of 10 MPa. Then, the exhaust valve on the high-pressure reactor is opened to reduce the pressure to atmospheric pressure, and cooling water is introduced into the cooling system of the reactor to obtain polyvinyl chloride supercritical gas co-foamed board.

[0048] Example 3: A method for preparing nano-bismuth oxychloride in this example includes the following steps:

[0049] 12.4 g of bismuth nitrate pentahydrate, 1 g of potassium chloride, and 250 mL of deionized water were mixed and sonicated for 15 min. The mixture was then stirred at 25 °C for 40 min. A 1 mol / L sodium hydroxide solution was added to adjust the pH to 6, and the mixture was stirred at 25 °C for 4 h. The mixture was then reacted in an autoclave at 180 °C for 10 h. After cooling, the mixture was washed three times each with deionized water and anhydrous ethanol. The mixture was filtered to obtain a filter cake. The filter cake was added to an autoclave, and carbon dioxide gas was introduced. The mixture was vented three times. The autoclave was maintained at 18 °C for 2.5 h at a pressure of 5.5 MPa for supercritical drying. The mixture was then maintained at 40 °C for 1.5 h at a pressure of 7.4 MPa under normal pressure. After cooling, nano-bismuth oxychloride was obtained.

[0050] The preparation method of a flame-retardant plasticizer according to this embodiment includes the following steps:

[0051] S1. Add 41.2 g of monooctyl phthalate, 75 g of thionyl chloride and 0.5 g of 1-methylpyrrolidine to a flask and stir. Stir at 118 °C for 10 h, collect the gas, distill, and distill under reduced pressure to obtain the acyl chloride product. Add 62 g of 10-chloro-1-decyl alcohol to the flask, then add the obtained acyl chloride product and 400 mL of dichloromethane solvent. Stir at 15 °C for 4 h. After the reaction is complete, wash with deionized water, dry, filter and rotary evaporate, and finally distill under reduced pressure to obtain intermediate product 1.

[0052] S2. Add 2.4g of intermediate product 1 and 2g of 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane to n-butanol solvent, stir evenly, heat to 76℃, react for 25h, after the reaction is completed, rotary evaporate, wash with deionized water, dry to obtain intermediate product 2.

[0053] S3. Mix 3g of nano-bismuth oxychloride with 40mL of 96wt% ethanol solution, heat at 60℃ for 20min, then add 8g of intermediate product 2, stir at 60℃ for 6h, vacuum dry, filter, and obtain flame-retardant plasticizer.

[0054] This embodiment describes a polyvinyl chloride supercritical gas co-foamed board and its preparation process, which includes the following steps:

[0055] Step 1: Mix 50g of polyvinyl chloride resin, 25g of flame retardant plasticizer, 4g of nano calcium carbonate, 2g of epoxidized soybean oil, 2g of calcium-zinc stabilizer, 0.2g of polyethylene wax and 0.2g of oxidized polyethylene wax at a mixing temperature of 184℃ and a rotation speed of 50r / min. Then press the mixture at 192℃ for 12min at a pressing pressure of 10MPa to obtain the pressed material.

[0056] The second step involves placing the obtained pressed material in a high-pressure reactor, introducing carbon dioxide gas, venting the reactor three times, maintaining the reactor at 82°C for 3 hours, and a pressure of 9 MPa. Then, the exhaust valve on the high-pressure reactor is opened to reduce the pressure to atmospheric pressure, and cooling water is introduced into the cooling system of the reactor to obtain polyvinyl chloride supercritical gas co-foamed board.

[0057] Comparative Example 1: The polyvinyl chloride supercritical gas co-foamed board provided in this comparative example is the same as that in Example 3, except that the flame-retardant plasticizer in Example 3 is replaced with intermediate 2 in Comparative Example 1.

[0058] Comparative Example 2: The polyvinyl chloride supercritical gas co-foamed board provided in this comparative example is the same as that in Example 3, except that the flame retardant plasticizer in Example 3 is replaced with dioctyl phthalate in Comparative Example 2.

[0059] The tensile properties of PVC and its composites were tested using a WDW-10D microcomputer-controlled electronic universal testing machine at a speed of 50.0 mm / min, with five parallel sets of samples. The oxygen index was collected using a JF-3 oxygen index tester with a sample size of 100 mm × 6.5 mm × 3 mm. The vertical burning test was performed according to UL94. The migration resistance test and solvent extraction resistance test were conducted. The samples were cut into 1 cm × 1 cm pieces with a thickness of about 2 mm, with 3 pieces per set. The surface of the samples was wiped clean and dried in a desiccator for 4 hours. The mass of the samples was accurately weighed on an analytical balance. The samples were placed in a certain amount of deionized water at room temperature. After 48 hours, they were taken out, wiped dry, and placed in an oven to continue drying for 48 hours. The mass of the samples was then weighed, and the mass loss rate of the samples was calculated using formula (1): Mass loss rate (%) = (m o —m l ) × 100% formula (1); m o The mass of the sample before testing is represented by m. l The sample quality is indicated after the test. The inhibition rate of Escherichia coli was tested according to GB / T31402 standard, and the inhibition rate of Escherichia coli was tested again after standing at room temperature for 180 days according to QB / T2591 standard. The retention rate was calculated. The specific test results are shown in Table 1.

[0060] Table 1: Test results of flame retardant and mechanical properties of each embodiment and comparative example

[0061] LOI / % Tensile strength / MPa UL94 rating Loss rate (%) Example 1 30.2 22.4 V-0 0.005 Example 2 29.8 21.6 V-0 0.004 Example 3 30.4 23.5 V-0 0.004 Comparative Example 1 25.0 16.4 V-1 0.005 Comparative Example 2 24.3 16.7 V-1 0.008

[0062] As shown in the table above, compared with Comparative Examples 1-2, the LOI in Examples 1-3 remained at 29.8-30.4%, the tensile strength was 21.6-23.5 MPa, the vertical burning test was V-0, and the loss rate was between 0.004-0.005%, indicating that the obtained PVC supercritical gas co-foamed board has excellent flame retardant properties, mechanical properties, and migration resistance.

[0063] Table 2: Antibacterial test results of each example and comparative example

[0064] Antibacterial rate (%) Antibacterial retention rate (%) Example 1 99.6 98.8 Example 2 99.2 98.2 Example 3 99.7 98.6 Comparative Example 1 99.2 98.3 Comparative Example 2 98.8 95.8

[0065] As can be seen from the data in the table above, the polyvinyl chloride supercritical gas co-foamed board prepared by this invention has good antibacterial properties.

[0066] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A polyvinyl chloride supercritical gas co-foamed sheet and a process for preparing the same, characterized in that, Includes the following steps: Step 1: Prepare the following parts by weight: 100 parts polyvinyl chloride resin, 40-60 parts flame retardant plasticizer, 5-15 parts nano calcium carbonate, 2-5 parts epoxidized soybean oil, 3-6 parts calcium-zinc stabilizer, 0.2-0.5 parts polyethylene wax, and 0.2-0.6 parts oxidized polyethylene wax. The second step involves mixing polyvinyl chloride resin, modified dioctyl phthalate, nano-calcium carbonate, epoxidized soybean oil, calcium-zinc stabilizer, polyethylene wax, and oxidized polyethylene wax at a mixing temperature of 180-190℃ and a rotation speed of 40-60 r / min. Then, the mixture is pressed at 190-200℃ for 8-15 minutes at a pressing pressure of 8-12 MPa to obtain the pressed material. The third step is to place the obtained pressed material in a high-pressure reactor, introduce carbon dioxide gas, exhaust the gas 2-4 times, maintain the temperature inside the reactor at 75-85℃ for 2-4 hours, and maintain the pressure at 8-10MPa. Then, open the exhaust valve on the high-pressure reactor to reduce the pressure to atmospheric pressure, and introduce cooling water into the cooling system of the reactor to obtain polyvinyl chloride supercritical gas co-foamed board.

2. The polyvinyl chloride supercritical gas co-foamed board and its preparation process according to claim 1, characterized in that, The preparation method of the flame-retardant plasticizer includes the following steps: S1. Add monooctyl phthalate, thionyl chloride and catalyst to a flask and stir. At 115-125℃ for 9-12 h, collect the gas, distill, and distill under reduced pressure to obtain the acyl chloride product. Pour 10-chloro-1-decyl alcohol into the flask, add the obtained acyl chloride product and dichloromethane solvent, and stir at 10-20℃ for 3-5 h. After the reaction is completed, wash with deionized water, dry, filter and rotary evaporate, and finally distill under reduced pressure to obtain intermediate product 1. S2. Add intermediate product 1 and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane to n-butanol solvent, stir evenly, heat to 72-80℃, react for 20-30h, rotary evaporate after reaction, wash with deionized water, dry to obtain intermediate product 2. S3. Mix nano-bismuth oxychloride with 92-98wt% ethanol solution, heat at 55-65℃ for 15-30 min, then add intermediate product 2, stir at 55-65℃ for 4-8 h, vacuum dry, filter, and obtain flame retardant plasticizer.

3. The polyvinyl chloride supercritical gas co-foamed board and its preparation process according to claim 2, characterized in that, The catalyst includes one or more of 1-methylpyrrolidine, 1-methylpiperidine, 1-ethylpiperidine, and 3-methylpyridine.

4. The preparation process of a polyvinyl chloride supercritical gas co-foamed board according to claim 2, characterized in that, In S1, the ratio of monooctyl phthalate, thionyl chloride, catalyst, and 10-chloro-1-decyl alcohol is (80-84)g:150g:1g:114-130g.

5. The polyvinyl chloride supercritical gas co-foamed board and its preparation process according to claim 2, characterized in that, In S2, the ratio of intermediate product 1 to 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane is (1.1-1.3) g:1 g.

6. The polyvinyl chloride supercritical gas co-foamed board and its preparation process according to claim 2, characterized in that, In S3, the ratio of intermediate product 2 to nano-bismuth oxychloride is (2.4-2.8) g:1 g.

7. The polyvinyl chloride supercritical gas co-foamed board and its preparation process according to claim 2, characterized in that, The preparation method of the nano-bismuth oxychloride includes the following steps: Bismuth nitrate pentahydrate, potassium chloride, and deionized water were mixed and sonicated for 10-20 min, then stirred at room temperature for 30-50 min. A 0.8-1.2 mol / L sodium hydroxide solution was then added to adjust the pH to 5.5-6.

5. The mixture was stirred at room temperature for 3-5 h, then reacted in an autoclave at 175-185℃ for 8-12 h. After cooling, the mixture was washed 2-3 times each with deionized water and anhydrous ethanol, filtered, and a filter cake was obtained. The filter cake was added to an autoclave, and carbon dioxide gas was introduced. The mixture was vented 2-3 times, and the autoclave was maintained at 15-20℃ for 2-3 h at a pressure of 5-6 MPa. The mixture was then subjected to supercritical drying, cooled to atmospheric pressure, and nano-bismuth oxychloride was obtained.

8. The polyvinyl chloride supercritical gas co-foamed board and its preparation process according to claim 7, characterized in that, The ratio of bismuth nitrate pentahydrate to potassium chloride is (6-6.5) g: 1 g.

9. The polyvinyl chloride supercritical gas co-foamed board and its preparation process according to claim 7, characterized in that, The conditions for supercritical drying are: maintaining at 35-45℃ for 1-2 hours and a pressure of 7-8 MPa.

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