Flame-retardant polyvinyl chloride elastomer, preparation method thereof, and sealing strip

Abstract

The present invention discloses a flame-retardant polyvinyl chloride elastomer, its preparation method, and a sealing strip. Polyvinyl chloride, a heat stabilizer, MBS, ACR, stearic acid or a stearate, and copper-doped magnesium-aluminum hydrotalcite are used as raw materials. The flame-retardant polyvinyl chloride elastomer is produced through blending, extrusion, and granulation. The elastomer is then co-extruded with a sealing strip skeleton to form the sealing strip. The present invention primarily addresses the prior art issue of poor dispersibility of hydrotalcite in polyvinyl chloride substrates.

Description

Technical Field

[0001] The invention relates to the technical field of polyvinyl chloride elastomer modification, in particular to the field of polyvinyl chloride elastomer flame retardant modification. Background Art

[0002] Polyvinyl chloride (PVC) is the world's second-largest general-purpose resin. However, due to structural defects such as allyl chloride in the PVC molecule, its thermal stability during processing and molding is poor. Therefore, heat stabilizers must be added during processing to mitigate its thermal degradation. PVC heat stabilizers are mainly divided into three types: lead salts, metal soaps, and organotin types. Metal soap heat stabilizers account for the largest proportion, followed by lead salts. However, because both lead salts and organotin heat stabilizers are toxic and have a certain destructive effect on the environment, metal soap heat stabilizers will occupy a larger market share in the future. Synthetic hydrotalcite, as an auxiliary stabilizer for metal soaps, is expected to continue to grow in market share.

[0003] Synthetic hydrotalcite (LDH), a layered compound that is free of lead and other heavy metals, serves as a co-stabilizer for stearate. It exhibits significantly higher thermal stability than commonly used organometallic salts while also possessing exceptional transparency. As a PVC heat stabilizer, synthetic hydrotalcite neutralizes and absorbs HCl released by thermal degradation, inhibiting the autocatalytic nature of PVC thermal degradation. It is non-toxic, harmless, safe, and environmentally friendly. As a halogen absorber, synthetic hydrotalcite effectively eliminates halogens and catalyst residues from polyolefin resins, thereby preventing gel formation and equipment corrosion.

[0004] The laminate of LDH is mainly composed of brucite-like materials, and some divalent cations are replaced by trivalent cations, resulting in a positive charge on the laminate. In order to show electrical neutrality, anions will be incorporated into the interlayer of LDH. At the same time, the hydroxyl groups on the laminate are connected to anions or water molecules through hydrogen bonds, which makes them easily agglomerated. At the same time, LDH is an inorganic compound with poor compatibility and dispersibility with organic matrix materials, which ultimately leads to low flame retardant efficiency and poor mechanical properties of the matrix composite material. Therefore, the poor dispersibility of LDH in PVC substrate is one of the focuses that need to be solved in this application.

[0005] Carbon microspheres (CMS) are emerging spherical carbon nanomaterials with thermal stability, high electronic conductivity, and high specific surface area. They are primarily used as heavy metal ion adsorbents, electrode materials, and catalysts. Using CMS as a flame retardant can improve the carbon layer of polymer materials because CMS participates in the formation of the carbon layer through thermal migration, filling the vacancies in the carbon layer and improving the structure of the carbon layer, thereby increasing the degree of graphitization of the carbon layer. However, when CMS is added to a polymer as a single flame retardant, the polymer releases a large amount of black smoke during combustion. In this case, the polymer material will fail the smoke density performance test requirements. Summary of the Invention

[0006] The object of the present invention is to provide a rubber composition and a preparation method thereof, so as to solve the problems of low flame retardant efficiency and poor mechanical properties of LDH / PVC composite materials proposed in the background art.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A flame-retardant polyvinyl chloride elastomer, comprising the following materials in parts by weight:

[0009] 100 parts of PVC, 4-10 parts of heat stabilizer, 1-3 parts of MBS, 2-5 parts of ACR, 0.3-1.5 parts of stearic acid or stearate, 3-30 parts of copper-doped magnesium aluminum hydrotalcite.

[0010] Specifically, the preparation method of the copper-doped magnesium-aluminum hydrotalcite comprises: preparing (Mg 2+ +Al 3+ ):Cu 2+ : urea = 12:4:25, after ultrasonic dispersion, the temperature is raised to 80-90 ° C and stirred for 14-16 hours, and then filtered, washed and dried to obtain the product.

[0011] Specifically, 3-25 parts of cerium-loaded carbon microspheres are also added.

[0012] Specifically, the preparation method of the cerium-loaded carbon microspheres includes: mixing 10 g of carbon microspheres with 0.1 mol of cerium nitrate solution, ultrasonically dispersing for 0.5-1 h, stirring for 1-1.5 h, and finally aging at room temperature for 4.5-7 h.

[0013] Specifically, the copper-doped magnesium-aluminum hydrotalcite is cerium-loaded carbon microspheres-copper-doped magnesium-aluminum hydrotalcite.

[0014] Specifically, the preparation method of the cerium-loaded carbon microspheres-copper-doped magnesium-aluminum hydrotalcite includes: taking 5g of cerium-loaded carbon microspheres and ultrasonically dispersing them in a solvent, adjusting the pH to 10-11, adding 20g of copper-doped magnesium-aluminum hydrotalcite, heating to 85-90°C, reacting for 6-7h, filtering, washing, and drying to obtain the product.

[0015] Specifically, the cerium-loaded carbon microspheres-copper-doped magnesium aluminum hydrotalcite is cerium-loaded carbon microspheres-phosphorus-nitrogen modified copper-doped magnesium aluminum hydrotalcite.

[0016] Specifically, the preparation method of the cerium-loaded carbon microspheres-phosphorus-nitrogen modified copper-doped magnesium-aluminum hydrotalcite includes: taking 5g of cerium-loaded carbon microspheres and ultrasonically dispersing them in a solvent, adjusting the pH to 10-11, adding 20g of copper-doped magnesium-aluminum hydrotalcite, and dropwise adding 100ml of 0.15mol / L ammonium phosphate solution, heating to 85-90°C and reacting for 6-7h, and then filtering, washing, and drying to obtain the product.

[0017] A method for preparing a flame retardant polyvinyl chloride elastomer comprises the following steps: uniformly mixing any of the above materials, melting and plasticizing at 175-190° C., and then granulating the mixture to obtain the flame retardant polyvinyl chloride elastomer.

[0018] A sealing strip is obtained by extruding the granules obtained by granulation together with a sealing strip skeleton material.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. Conventional organic modified hydrotalcite often requires the use of organic solvents, and the intercalation steps of hydrotalcite and other materials are cumbersome. In comparison, it is easier to dope other metals into hydrotalcite. MgAl-LDH sheets are composed of regular octahedrons (composed of six MO bonds) with common edges. When part of the Mg in the laminate 2+ Cu 2+ When substituted, due to Cu 2+ Due to the Jan-Taylor effect, some Mg-O regular octahedra will be transformed into Cu-O elongated octahedra, resulting in a decrease in the regularity and crystallinity of the laminate, as well as deformation of the laminate, which in turn leads to a larger interlayer spacing, making it easier for polymer chains to enter the interlayer and improving the diffusion effect of hydrotalcite.

[0021] 2. Cu 2+ The irregularities of the hydrotalcite laminate surface caused by the Jan-Taylor effect also increase the specific surface area of the hydrotalcite laminate, significantly increasing the growth sites for hydroxyl and carboxyl groups. Finally, the reduction in hydrotalcite crystallinity also reduces the stability of hydroxyl groups on the hydrotalcite surface, which increases the possibility of exchange between phosphate and hydroxyl ligands, making ammonium phosphate more easily adsorbed on the hydrotalcite and co-dispersed with the hydrotalcite in the polymer matrix.

[0022] 3. The thermal stability of PVC composite materials after adding CuMgAl-LDH is improved, and the smoke density is significantly reduced. On the one hand, Cu 2+The smoke suppression performance of PVC plays a role. On the other hand, rare earth elements can react with HCl produced during the degradation of PVC to form CeCl3, which reduces the catalytic effect of HCl on the degradation of PVC, thereby achieving the purpose of enhancing the thermal stability of PVC. At the same time, rare earth elements also act as acid sites to promote the carbonization of materials, catalyzing the decomposition reaction to produce thick smoke. The significant improvement in the residual carbon rate is mainly due to Cu 2+ The catalytic cross-linking effect forms a more stable carbon layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the hydrotalcite modification method in this application.

[0024] Figure 2 This is a schematic diagram of the preparation method of rare earth modified carbon microspheres in this application.

[0025] Figure 3 This is a schematic diagram of the preparation method of the rare earth modified carbon microspheres and modified hydrotalcite composite material in this application. DETAILED DESCRIPTION

[0026] In order to make the technical means, distinguishing features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific embodiments.

[0027] Unless otherwise specified, all raw materials and reagents used in the examples of the present invention are commercially available, and parts are by mass unless otherwise specified.

[0028] Preparation of carbon microspheres: 0.12 mol of xylose (chemically pure) was ultrasonically dissolved in 300 ml of deionized water, transferred to a hydrothermal reactor, heated to 180 ° C and reacted for 12 hours. After cooling to room temperature, the crude product was obtained by filtration, washing, drying and grinding. Subsequently, 100 ml of a mixture of HNO3 / H2SO4 (1:3) was added to 20 g of the crude product, heated to 55-60 ° C and stirred continuously for 10 hours to remove impurities and promote the production of functional groups such as carboxyl and hydroxyl groups. After the reaction is completed, the obtained black suspension is centrifuged and dried in a 60 ° C oven for 10 hours, marked as CMS.

[0029] Preparation of cerium-loaded carbon microspheres: 10 g of the above-mentioned CMS was added to 100 mL of 1 mol / L cerium nitrate solution. After ultrasonic-assisted dispersion for 0.5 h, mechanical stirring was continued for 1 h. The mixture was then aged at 25°C for 5 h. Finally, the precipitate was filtered, washed, dried, and ground to obtain Ce-CMS.

[0030] Preparation of copper-doped magnesium-aluminum hydrotalcite material: Take 50 ml of 1.2 mol / L Mg(NO3)2 and Al(NO3)3 solution, add 0.2 mol / L Cu(NO3)2 solution, and make the (Mg)2+ +Al 3+ ):Cu 2+ =3:1, then add 0.25 mol of urea. After ultrasonic dispersion for 15 minutes, heat to 85°C and stir for 14-16 hours. After the reaction, centrifuge to obtain the precipitate, wash with deionized water, and dry in a 60°C oven for 10 hours. The labeled product is CuMgAl-LDH.

[0031] Preparation of cerium-loaded carbon microspheres-copper-doped magnesium-aluminum hydrotalcite composites: 5 g of Ce-CMS was ultrasonically dispersed in 150 ml of deionized water, and the pH was adjusted to 10-11 with 0.1 mol / L NaOH solution. Then 20 g of CuMgAl-LDH was added, and the mixture was heated to 85°C and reacted for 6 hours after vigorous stirring. After the solution was cooled to room temperature, the precipitate was obtained by centrifugation, washed with deionized water, and dried in an oven at 60°C for 10 hours. The product was labeled Ce-CMS@CuMgAl-LDH.

[0032] Preparation of cerium-loaded carbon microspheres-phosphorus-nitrogen modified copper-doped magnesium-aluminum hydrotalcite composites: 5 g of Ce-CMS was ultrasonically dispersed in 150 ml of deionized water, and the pH was adjusted to 10-11 with 0.1 mol / L NaOH solution. Then 20 g of CuMgAl-LDH was added, and after vigorous stirring, 100 ml of 0.15 mol / L (NH4)3PO4 solution was added dropwise (while stirring). The temperature was raised to 85 ° C and the reaction was carried out for 6 hours. After the solution was cooled to room temperature, the precipitate was obtained by centrifugation, washed with deionized water, and dried in an oven at 60 ° C for 10 hours. The product was labeled Ce-CMS@PNCuMgAl-LDH.

[0033] Preparation of PVC composite material: 100g of PVC, 4g of calcium-zinc stabilizer, 2g of MBS, 3g of ACR, and 0.4g of stearic acid were weighed as the base raw material formula. After adding the modified materials, the mixture was mixed in a high-speed mixer at (900±20) r / min for 10 minutes. After stirring evenly, the mixture was discharged. Subsequently, the mixture was melt-plasticized and sheeted in a two-roll mill at 185°C. The sheet was then pressed on a flat-plate vulcanizer to prepare standard test bars for performance testing.

[0034] Preparation method of sealing strip: after the above-mentioned PVC composite material is extruded and granulated, it is put into an extruder and extruded together with a metal skeleton, a plastic skeleton or a rubber skeleton. During extrusion, the processing temperature is controlled at 160℃~180℃, and the die temperature is controlled at 170-180℃. After conventional processes such as cutting and trimming, the sealing strip can be obtained.

[0035] In the following comparative examples and embodiments, during actual production or testing, 3-10 parts of dioctyl phthalate (DOP) may be added to assist in the plasticization of PVC; the stearic acid may also be replaced by conventional stearates such as zinc stearate and calcium stearate.

[0036] LOI test: refer to GB / T 2406 test; vertical burning grade (UL 94) test: refer to GB / T 2408 test; tensile performance test: refer to GB / T 1040-2006, tensile rate is 50mm / min; smoke density test: test according to GB / T 8627-2007, heat radiation power is set to 25k W / m 2 Thermal stability: Tested using a torque rheometer under the following conditions: material temperature 185°C, test load 5kg, rotation speed 35rpm. Test method: After 15 minutes of mixing in the torque rheometer, remove the sample and measure initial whiteness using a colorimeter. Separate samples are also taken for dynamic thermal stability testing. Weight loss on heating: Tested in accordance with GB / T 21282-2007. Hot air aging: Tested in accordance with GB / T 7141, test conditions: 100°C x 72h. Carbon residue: The ratio of carbon residue after combustion to the sample mass before combustion. For standards without a specified year, the latest standard shall be used for testing.

[0037] Comparative Example 1: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of methyl methacrylate-butadiene-styrene copolymer (MBS), 3 g of acrylate modifier (ACR), and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and standard test specimens were prepared after stirring, plasticating, and pressing.

[0038] Comparative Example 2: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 5 g of magnesium aluminum hydrotalcite was added. The standard test specimens were prepared after stirring, plasticating, and pressing.

[0039] Comparative Example 3: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 20 g of magnesium aluminum hydrotalcite was added. The standard test specimens were prepared after stirring, plasticating, and pressing.

[0040] Comparative Example 4: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 5 g of benzoic acid intercalation-modified magnesium aluminum hydrotalcite (preparation method reference: Gao Dali, Wu Daming, Liu Ying, Meng Zhaohui. Organic modification of nano-hydrotalcite (LDH) and its dispersion in polymers [J]. Plastics Industry, 2005(08):54-56.) was prepared. Standard test specimens were prepared after stirring, plasticating, and pressing.

[0041] Comparative Example 5: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, 20 g of benzoic acid intercalated modified magnesium aluminum hydrotalcite (preparation method refers to Comparative Example 4), and standard test specimens were prepared after stirring, plasticating, and pressing.

[0042] Example 1: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 5 g of carbon microspheres were stirred, plasticized, and pressed to prepare standard test specimens.

[0043] Example 2: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 20 g of carbon microspheres were stirred, plasticized, and pressed to prepare standard test specimens.

[0044] Example 3: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 5 g of Ce-CMS were stirred, plasticated, and pressed to produce standard test specimens.

[0045] Example 4: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 20 g of Ce-CMS was stirred, plasticated, and pressed to produce standard test specimens.

[0046] Example 5: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, 10 g of carbon microspheres, and 10 g of Ce-CMS were stirred, plasticated, and pressed to produce standard test specimens.

[0047] Example 6: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, 10 g of carbon microspheres, and 10 g of magnesium aluminum hydrotalcite were stirred, plasticized, and pressed into plates to prepare standard test specimens.

[0048] Example 7: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, 10 g of Ce-CMS, and 10 g of magnesium aluminum hydrotalcite were stirred, plasticated, and pressed to produce standard test specimens.

[0049] Example 8: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, 10 g of carbon microspheres, and 10 g of benzoic acid intercalated modified magnesium aluminum hydrotalcite were stirred, plasticized, and pressed to obtain standard test specimens.

[0050] Example 9: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, 10 g of Ce-CMS, and 10 g of benzoic acid intercalated modified magnesium aluminum hydrotalcite were stirred, plasticized, and pressed to obtain standard test specimens.

[0051]

[0052] A comprehensive analysis of Comparative Examples 1-5 reveals that directly adding magnesium-aluminum hydrotalcite to the base formula significantly deteriorates the material's mechanical properties, with minimal impact on its flame retardancy and thermal stability. This is primarily because hydrotalcite tends to aggregate within the polymer matrix, forming stress concentration points that can easily lead to rupture during the material's stretching process. The use of benzoic acid intercalation to modify the magnesium-aluminum hydrotalcite increases interlayer spacing, partially encouraging the incorporation of polymer chains between the hydrotalcite interlayers and promoting the dispersion of the hydrotalcite material, which is clearly reflected in its mechanical performance parameters. Furthermore, the hydrotalcite neutralizes and absorbs HCl released by PVC thermal degradation, inhibiting the autocatalytic effect of PVC thermal degradation. Consequently, the material's flame retardancy and carbon residue rate are significantly improved.

[0053] A comprehensive analysis of Comparative Examples 1-5 and Examples 1-2 shows that the addition of carbon microspheres improves the tensile strength of the PVC material to a certain extent, but the elongation at break parameter continues to deteriorate, the same as in Comparative Examples 2 and 3. It also has no effect on the thermal stability of the material, and even worsens the smoke density. This is because when CMS is added to the polymer as a single flame retardant, the polymer releases a large amount of black smoke when burned. However, using CMS as a flame retardant can improve the carbon residue layer of the polymer material because CMS participates in the formation of the carbon residue layer through thermal migration, filling the vacancies of the carbon residue and improving the structure of the carbon residue layer, thereby increasing the degree of graphitization of the carbon layer and, to a certain extent, improving the carbon residue rate of the material.

[0054] Continuing to analyze Comparative Examples 1-5 and Examples 3-5, Ce-CMS significantly improves the material's dynamic thermal stability compared to standard CMS, while having little effect on the material's mechanical properties. However, it significantly improves the material's flame retardancy, particularly with a significant decrease in the smoke density index and a significant increase in the carbon residue rate. This is primarily because rare earth elements react with HCl produced during PVC degradation to form CeCl3, reducing the HCl's catalytic effect on PVC degradation and thus enhancing the PVC's thermal stability. Furthermore, the rare earth elements act as acid sites, promoting carbonization in the material and catalyzing the decomposition of smoke.

[0055] Finally, analyzing Examples 6-9, we see that the combination of CMS and hydrotalcite significantly improves the material's elongation and carbon residue, while other properties show slight but insignificant improvements. We speculate that this is because the negative surface charge of CMS attracts the positive surface charge of hydrotalcite, forming a stable ionic bond, which promotes the dispersion of CMS and hydrotalcite within the polymer matrix, leading to the improved elongation. The improved carbon residue is a result of CMS improving the carbon residue layer of the polymer. The combination of Ce-CMS and hydrotalcite significantly improves the material's thermal properties, primarily because rare earth elements react with HCl produced during PVC degradation to form CeCl3, reducing the HCl's catalytic effect on PVC degradation and thereby enhancing the PVC's thermal stability. Furthermore, the rare earth elements act as acid sites, promoting carbonization and catalyzing the decomposition of fumes. The combination of CMS and Ce-CMS with benzoic acid-intercalated magnesium-aluminum hydrotalcite also significantly improves performance compared to Comparative Examples 4 and 5, particularly with regard to thermal properties. Judging from the thermal performance data alone, Ce-CMS has the most obvious impact on polymer materials. This conclusion can be drawn through a comprehensive analysis of comparative examples 3, 4, and 9.

[0056] Example 10: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 5 g of CuMgAl-LDH was stirred, plasticized, and pressed into plates to prepare standard test specimens.

[0057] Example 11: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 20 g of CuMgAl-LDH was stirred, plasticized, and pressed to produce standard test specimens.

[0058] Example 12: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, 10 g of carbon microspheres, and 10 g of CuMgAl-LDH were stirred, plasticized, and pressed to produce standard test specimens.

[0059] Example 13: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, 10 g of Ce-CMS, and 10 g of CuMgAl-LDH were stirred, plasticized, and pressed to produce standard test specimens.

[0060] Example 14: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, 5 g of carbon microspheres, 5 g of Ce-CMS, and 10 g of CuMgAl-LDH were mixed, plasticized, and pressed to produce standard test specimens.

[0061] Example 15: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 5 g of Ce-CMS@CuMgAl-LDH were stirred, plasticized, and pressed into plates to prepare standard test specimens.

[0062] Example 16: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 10 g of Ce-CMS@CuMgAl-LDH was stirred, plasticized, and pressed to produce standard test specimens.

[0063] Example 17: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 15 g of Ce-CMS@CuMgAl-LDH was stirred, plasticized, and pressed to produce standard test specimens.

[0064] Example 18: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 20 g of Ce-CMS@CuMgAl-LDH was stirred, plasticized, and pressed to produce standard test specimens.

[0065] Example 19: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 25 g of Ce-CMS@CuMgAl-LDH was stirred, plasticized, and pressed to produce standard test specimens.

[0066] Example 20: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 30 g of Ce-CMS@CuMgAl-LDH was stirred, plasticized, and pressed to produce standard test specimens.

[0067] Example 21: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 5 g of Ce-CMS@PNCuMgAl-LDH were stirred, plasticized, and pressed to produce standard test specimens.

[0068] Example 22: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 10 g of Ce-CMS@PNCuMgAl-LDH was stirred, plasticized, and pressed to produce standard test specimens.

[0069] Example 23: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 15 g of Ce-CMS@PNCuMgAl-LDH was stirred, plasticized, and pressed to produce standard test specimens.

[0070] Example 24: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 20 g of Ce-CMS@PNCuMgAl-LDH was stirred, plasticated, and pressed to produce standard test specimens.

[0071] Example 25: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 25 g of Ce-CMS@PNCuMgAl-LDH was stirred, plasticized, and pressed to produce standard test specimens.

[0072] Example 26: 100 g of PVC, 4 g of calcium zinc stabilizer, 2 g of MBS, 3 g of ACR, and 0.4 g of stearic acid were weighed as the basic formula of raw materials, and 30 g of Ce-CMS@PNCuMgAl-LDH was prepared after stirring, plasticating, and pressing.

[0073]

[0074]

[0075] Comprehensive analysis of comparative examples 2-5 and examples 10 and 11, as well as comprehensive analysis and comparison of examples 6, 7 and examples 12, 13 and 14, shows that CuMgAl-LDH is more effective than ordinary MgAl-LDH in enhancing the mechanical properties of PVC substrates, and is slightly improved compared with the performance of benzoic acid intercalation modified magnesium aluminum hydrotalcite. We believe that: Cu 2+ The addition of Cu increases the interlayer spacing of hydrotalcite, making it easier for polymer chains to enter the interlayers and improving the diffusion effect of hydrotalcite. The thermal stability is slightly improved and the smoke density is significantly reduced, mainly due to the presence of Cu 2+ The smoke suppression performance of Cu 2+ The catalytic cross-linking effect forms a more stable carbon layer.

[0076] Comprehensive analysis and comparison of Examples 15-20 show that the mechanical properties of the PVC material with only 5 parts of Ce-CMS@CuMgAl-LDH added are similar to those of the PVC material with 20 parts of CuMgAl-LDH added in Example 11, and are better than those of the previous examples. We speculate that this is because although Ce-CMS and CuMgAl-LDH have been modified, they may still have a certain degree of agglomeration. In the Ce-CMS@CuMgAl-LDH material, the electrons on the outer layer of Ce-CMS can be directly attracted by the positive charges on the surface of the hydrotalcite laminate, and some Ce 3+ They can also be attracted by the negative charges between the hydrotalcite layers, forming stable ionic bonds. At the same time, the irregularities of the laminate surface also increase the specific surface area, thereby greatly increasing the growth sites of hydroxyl and carboxyl groups and improving the reaction opportunities between Ce-CMS and CuMgAl-LDH. Furthermore, the PVC molecular chains can pass through the expanded hydrotalcite layer, achieving a high degree of dispersion of Ce-CMS@CuMgAl-LDH in the PVC substrate. This high dispersion also enhances the material's heat resistance, fully neutralizing and absorbing the HCl released by PVC due to thermal degradation, inhibiting the catalytic degradation of PVC during thermal degradation, and improving the material's flame retardancy and the carbon residue rate after combustion.

[0077] A comprehensive analysis and comparison of Examples 21-26 with Examples 15-20 reveals that the flame retardancy of Ce-CMS@CuMgAl-LDH modified with ammonium phosphate (PN) functionalization is significantly improved. We hypothesize that the reduced crystallinity of the hydrotalcite also reduces the stability of the hydroxyl groups on the hydrotalcite surface, increasing the possibility of exchange between phosphate and hydroxyl ligands. This makes ammonium phosphate more easily adsorbed on the hydrotalcite and co-dispersed with the hydrotalcite in the polymer matrix, forming an intumescent flame retardant system with phosphorus as the acid source, ammonium (nitrogen) as the gas source, and CMS as the carbon source. During the combustion of the PVC material, Ce-CMS@PNCuMgAl-LDH migrates to the surface under the heat flow, and the ammonium phosphate decomposes into ammonia and phosphorus-containing substances. Under the influence of high temperature, the phosphorus-containing substances interact with Cu and Ce, allowing more phosphorus to function in the condensed phase. The polyphosphoric acid bound to Cu and Ce dehydrates and crosslinks with the PVC and CMS, rapidly forming a dense and compact carbon layer, which ultimately acts as a shield.

[0078] Hot air aging performance test was additionally conducted on some comparative examples and embodiments to compare the performance change rate of PVC materials before and after hot air aging.

[0079]

[0080]

[0081] By analyzing the above table and the previous two tables, we can find that the results of the hot air aging performance test are basically consistent with the changes in initial whiteness and dynamic thermal stability time in the previous table, that is, both Ce-CMS@CuMgAl-LDH and Ce-CMS@PNCuMgAl-LDH have good anti-aging properties.

[0082] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be regarded as illustrative and non-restrictive in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and all changes that come within the meaning and range of equivalents of the claims are intended to be included therein.

[0083] In addition, it should be understood that although this specification is described in accordance with the implementation methods and drawings, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A flame retardant polyvinyl chloride elastomer, characterized in that: Including the following materials by weight: PVC 100 parts, heat stabilizer 4-10 parts, MBS 1-3 parts, ACR 2-5 parts, stearic acid or stearate 0.3-1.5 parts, copper-doped magnesium aluminum hydrotalcite 3-30 parts, cerium-loaded carbon microspheres 3-25 parts, The preparation method of the cerium-loaded carbon microspheres comprises: mixing 10 g of carbon microspheres with 0.1 mol of cerium nitrate solution, dispersing the mixture by ultrasonication for 0.5-1 h, stirring the mixture for 1-1.5 h, and finally aging the mixture at room temperature for 4.5-7 h.

2. The flame retardant polyvinyl chloride elastomer according to claim 1, characterized in that: The preparation method of the copper-doped magnesium-aluminum hydrotalcite comprises: preparing (Mg 2+ +Al 3+ ):Cu 2+ : urea = 12:4:25, after ultrasonic dispersion, the temperature is raised to 80-90 ° C and stirred for 14-16 hours, and then filtered, washed and dried to obtain the product.

3. The flame retardant polyvinyl chloride elastomer according to claim 1, characterized in that: The copper-doped magnesium-aluminum hydrotalcite is cerium-loaded carbon microspheres-copper-doped magnesium-aluminum hydrotalcite.

4. The flame retardant polyvinyl chloride elastomer according to claim 3, characterized in that: The preparation method of the cerium-loaded carbon microspheres-copper-doped magnesium-aluminum hydrotalcite comprises: taking 5g of cerium-loaded carbon microspheres and ultrasonically dispersing them in a solvent; adjusting the pH to 10-11; adding 20g of copper-doped magnesium-aluminum hydrotalcite; heating to 85-90°C for reaction for 6-7h; and filtering, washing, and drying to obtain the product.

5. The flame retardant polyvinyl chloride elastomer according to claim 3, characterized in that: The cerium-loaded carbon microspheres-copper-doped magnesium aluminum hydrotalcite is cerium-loaded carbon microspheres-phosphorus-nitrogen modified copper-doped magnesium aluminum hydrotalcite.

6. The flame retardant polyvinyl chloride elastomer according to claim 5, characterized in that: The preparation method of the cerium-loaded carbon microspheres-phosphorus-nitrogen modified copper-doped magnesium-aluminum hydrotalcite comprises: taking 5g of cerium-loaded carbon microspheres and ultrasonically dispersing them in a solvent; adjusting the pH to 10-11; adding 20g of copper-doped magnesium-aluminum hydrotalcite; and dropwise adding 100ml of a 0.15mol / L ammonium phosphate solution; heating to 85-90°C and reacting for 6-7h; and filtering, washing, and drying to obtain the product.

7. A method for preparing a flame retardant polyvinyl chloride elastomer, characterized in that: The flame retardant polyvinyl chloride elastomer is prepared by uniformly mixing the raw materials of any one of claims 1 to 6, melting and plasticizing them at 175-190° C., and then granulating them.

8. A sealing strip, characterized in that: The pellets prepared by the preparation method according to claim 7 are co-extruded with a skeleton material to obtain the product.

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