Novel PVC (Polyvinyl Chloride) functional auxiliary agent for inhibiting release of toxic plasticizer as well as preparation method and application of novel PVC functional auxiliary agent

Abstract

The invention provides a novel PVC (polyvinyl chloride) functional aid for inhibiting release of toxic plasticizers as well as a preparation method and application of the novel PVC functional aid, and relates to the technical field of PVC functional aids. The preparation method of the PVC functional auxiliary agent comprises the steps of co-precipitation of a precursor solution and a modifier solution, crystallization, drying and the like, and the PVC functional auxiliary agent based on the layered double hydroxide structure is finally obtained. The PVC functional auxiliary agent effectively inhibits migration of harmful substances in PVC through surface adsorption and the space resistance effect of nanoparticles, the volatility resistance and migration resistance of a PVC film are remarkably improved, potential threats of PVC products to the environment and human health are reduced, and an effective scheme is provided for improving the biological safety of PVC. According to the invention, the sustainable development and safe application of the PVC material are assisted, and the PVC industry is promoted to transform towards greenization and high performance.

Description

Technical Field

[0001] The present invention relates to the technical field of PVC functional additives, and particularly to a PVC functional additive, a preparation method thereof, and an application thereof. Background Art

[0002] As a widely used plastic material, PVC has posed potential threats to humans and the environment during its production and application processes. From the aging, combustion to the toxicity problems of PVC, every link reveals its potential risks. Over time, the severity of these problems has been increasing, and the damage to human health and the ecosystem has become increasingly obvious. Notably, although current research mainly focuses on the safety assessment of plasticizers, the safety assessment of PVC heat stabilizers is still a blank field in China. This situation not only restricts the further improvement of the safety performance of PVC products but also may pose potential threats to the ecosystem.

[0003] Therefore, developing new green, non-toxic, and multifunctional PVC heat stabilizers to improve their comprehensive performance and effectively inhibit the release of harmful substances has become an extremely challenging and important topic. Existing heat stabilizers include lead salts, organotin compounds, metal soaps, etc. However, lead salts and organotin have environmental safety problems, and metal soaps are prone to the phenomenon of "zinc burning" and need to be used in combination with other stabilizers. In addition, dioctyl terephthalate (DOTP) is the most widely used PVC plasticizer at present. However, DOTP has poor migration resistance and volatility resistance in PVC films, which may pose potential threats to the ecosystem.

[0004] Therefore, it is necessary to develop a new type of environmentally friendly, multifunctional PVC functional additive that can inhibit the release of toxicity to improve the durability and safety of PVC materials. Summary of the Invention

[0005] In view of this, the present invention provides a new type of PVC functional additive for inhibiting the release of toxic plasticizers, a preparation method thereof, and an application thereof. The present invention conducts intercalation modification on a specific hydrotalcite-like compound through a specific modifier, and finally obtains a functional additive based on a layered double hydroxide structure, which can effectively inhibit the migration of harmful substances (such as DOTP) in PVC, significantly improve the volatility resistance and migration resistance of PVC films, and provide an effective solution for improving the biosafety of PVC.

[0006] The preparation method of the PVC functional additive provided by the present invention includes the following steps:

[0007] S1. Add a precursor to deionized water to obtain solution A;

[0008] S2. Add a modifier and a precipitating agent to deionized water to obtain solution B;

[0009] S3. Under stirring conditions, add solution B dropwise to solution A for coprecipitation;

[0010] S4. After coprecipitation, carry out crystallization to obtain a crystallized slurry;

[0011] S5. Filter and dry the crystallized slurry to obtain a PVC functional additive.

[0012] Preferably, the precursor is at least two of magnesium salts, lanthanum salts and cerium salts. More preferably, the magnesium salts, lanthanum salts and cerium salts are at least two of Mg(NO3)2·6H2O, La(NO3)3·6H2O, Ce(NO3)3·6H2O.

[0013] Preferably, the precursor is composed of Mg(NO3)2·6H2O, La(NO3)3·6H2O, Ce(NO3)3·6H2O in a molar ratio of 0.04:(0 - 0.1):(0 - 0.1).

[0014] Preferably, the concentration of the precursor in solution A is 0.06 mol / 70 mL.

[0015] Preferably, the modifier is Na2CO3 or Na2HPO3.

[0016] Preferably, in solution B, the concentration of the modifier is 0.03 mol / 150 mL, the concentration of the precipitant is 0.18 mol / 150 mL, and the pH of solution B is 11.

[0017] Preferably, the volume ratio of solution A to solution B is 7:15, the coprecipitation temperature is 80°C - 120°C, and the coprecipitation time is 4 - 8 h.

[0018] Preferably, the crystallization temperature is 80°C - 120°C, and the crystallization time is 4 - 10 h. More preferably, the crystallization temperature is 80°C, and the crystallization time is 8 h.

[0019] Preferably, the drying temperature is 50°C - 80°C, and the drying time is 5 - 8 h. More preferably, the drying temperature is 80°C, and the drying time is 8 h.

[0020] Preferably, after filtering the crystallized slurry, the precipitate is washed with deionized water until the pH is 7.

[0021] The present invention also provides a PVC functional additive prepared according to the above method.

[0022] The present invention also provides an application of the PVC functional additive in inhibiting the release of harmful substances in PVC and improving the biosafety of PVC, and the PVC functional additive is the PVC functional additive described in the above technical solution.

[0023] Preferably, the harmful substance is DOTP.

[0024] The method for using the PVC functional additive of the present invention is as follows:

[0025] Mix PVC, DOTP, and the PVC functional additive in proportion and stir evenly. After vacuum degassing, coating, and plasticization, a soft PVC composite material is obtained.

[0026] Preferably, the mass ratio of PVC, DOTP, and the PVC functional additive is 100:75:5; the plasticization temperature is 180 °C, and the plasticization time is 3 min.

[0027] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0028] In the present invention, specific hydrotalcite-like compounds are modified by intercalation modification to obtain a novel PVC functional additive for inhibiting the release of toxic plasticizers. The PVC functional additive of the present invention has a layered double hydroxide structure. This additive effectively inhibits the migration of harmful substances, especially DOTP, through surface adsorption and the steric resistance of nanoparticles. At the same time, these particles remain relatively fixed in the matrix and show a strong affinity for DOTP. The PVC functional additive of the present invention significantly improves the volatility resistance and migration resistance of the PVC film, reduces the potential threat of PVC products to the environment and human health, promotes the sustainable development and safer application of PVC materials, and drives the transformation of the PVC industry towards green and high-performance directions. Description of the Drawings

[0029] The present invention will be further described below in conjunction with the description of the drawings.

[0030] Figure 1 Infrared spectra (A - B) and X-ray diffraction patterns (C) of the PVC functional additives obtained in Example 1 and Example 2;

[0031] Figure 2 SEM images of the PVC functional additives obtained in Example 1 and Example 2;

[0032] Figure 3 Effects of C / PVC and PVC prepared from the PVC functional additives obtained in Example 1 and Example 2 on the liver function (A - D), kidney function (E - F), and thyroid hormones (G) of SD rats, and liquid chromatogram (H) of the PVC leaching solution;

[0033] Figure 4 SEM images of the PVC functional additives obtained in Example 3 and Example 4;

[0034] Figure 5Infrared spectra (A-B) and X-ray diffraction patterns (C) of the PVC functional auxiliaries obtained in Example 3 and Example 4;

[0035] Figure 6 Pathological sections of H&E staining of various organs of P-LDH and corresponding P-LDH / PVC obtained in Example 3 and Example 4 in SD rats. Detailed implementation manners

[0036] The following will describe the technical solutions of the present invention clearly and completely in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0037] The present invention provides a novel PVC functional auxiliary for inhibiting the release of toxic plasticizers. The layered double hydroxide structure of this stabilizer can effectively inhibit the migration of DOTP plasticizers through surface adsorption and the steric resistance of nanoparticles. In addition, these particles remain relatively fixed in the matrix and show a strong affinity with DOTP, effectively inhibiting the migration of DOTP.

[0038] The preparation method of the PVC functional auxiliary described in the present invention includes the following steps:

[0039] S1. Add the precursor to deionized water to obtain solution A;

[0040] S2. Add the modifier and precipitant to deionized water to obtain solution B;

[0041] S3. Under N2 protection, drop solution B into solution A and stir for coprecipitation;

[0042] S4. Perform crystallization after coprecipitation to obtain a crystallized slurry;

[0043] S5. Filter and dry the crystallized slurry to obtain the PVC functional auxiliary.

[0044] The precursor in the present invention is preferably at least two of magnesium salts, lanthanum salts and cerium salts. In some specific embodiments of the present invention, the magnesium salt, lanthanum salt and cerium salt are at least two of Mg(NO3)2·6H2O, La(NO3)3·6H2O, Ce(NO3)3·6H2O. In some specific embodiments of the present invention, the precursor is composed of Mg(NO3)2·6H2O, La(NO3)3·6H2O, Ce(NO3)3·6H2O in a molar ratio of 0.04:(0-0.1):(0-0.1). The concentration of the precursor in the solution A of the present invention is 0.06 mol / (50-120) mL.

[0045] By regulating the types and ratios of the precursors, the present invention can ensure the structure and function of the layered double hydroxide, and achieve efficient inhibition of the migration of DOTP in PVC. First of all, magnesium salts, lanthanum salts and cerium salts have different chemical properties and functions, and can produce a synergistic effect when acting together. For example, magnesium can enhance the heat resistance of the material, while lanthanum and cerium can improve the antioxidant and stability of the material due to their unique electronic structures and redox properties. The combination of magnesium salts, lanthanum salts and cerium salts is also beneficial to the formation of a stable layered double hydroxide structure, which is crucial for exerting the surface adsorption and nanoparticle steric resistance effects. In addition, lanthanum and cerium have strong coordination abilities, and magnesium helps to provide a suitable layered structure framework, thereby optimizing the adsorption performance of the entire system for DOTP. Finally, by selecting the ratios of magnesium, lanthanum and cerium salts, the present invention can regulate the properties of the layered double hydroxide to achieve optimization for different PVC matrices.

[0046] The modifier in the present invention is preferably Na2CO3 or Na2HPO3, and the precipitant is preferably NaOH. In the solution B of the present invention, the concentration of the modifier is 0.03 mol / 150 mL, the concentration of the precipitant is 0.18 mol / 150 mL, and the pH of the solution B is preferably 11.

[0047] Na2CO3 can provide carbonate ions (CO3 2- ), which are easy to form stable layered double hydroxides with magnesium, lanthanum and cerium ions. CO3 2- has a small ionic radius and a high negative charge density, which helps to form a dense and stable layered structure, improving the thermal stability of the material and the adsorption ability for DOTP. NaH2PO4 can provide phosphate groups (PO4 2- ), which have a relatively large anion radius and can introduce more functional intercalation sites, enhancing the interlayer adsorption and steric hindrance effects. PO4 2-The migration of DOTP can be further inhibited by forming hydrogen bonds or coordination interactions with DOTP molecules. By selecting Na2CO3 or NaH2PO4 as the modifier in the present invention, the targeted regulation of the properties of hydrotalcite-like compounds can be achieved to meet the requirements of different PVC matrices for stabilizer properties. When the pH is 11, magnesium, lanthanum, and cerium ions can form a uniformly distributed layered structure, and the negative charge distribution is the most uniform, which can more effectively inhibit the migration of DOTP.

[0048] In the present invention, the volume ratio of solution A to solution B is preferably 7:15, the coprecipitation temperature is 80 °C to 120 °C, and the coprecipitation time is 4 to 8 h. In some preferred embodiments of the present invention, the CO3 2- For the anion intercalation modification, the coprecipitation temperature is 80 °C and the coprecipitation time is 8 h. For the PO3 2- For the anion intercalation modification, the coprecipitation temperature is 90 °C and the coprecipitation time is 4 h.

[0049] Solution A mainly contains precursors, while solution B contains a modifier and a precipitant. By limiting the volume ratio of solution A to solution B in the present invention, the problems of local supersaturation or non-uniform precipitation can be ensured, which helps to form a uniform layered double hydroxide precipitate. At the same time, the reaction rate can also be regulated, making the size of the generated precipitate particles relatively uniform and the dispersibility better. And the layered double hydroxide with uniform particle size helps to improve its inhibitory effect on the release of DOTP. Generally speaking, the volume ratio of solution A to solution B in the present invention can achieve the best balance among the reaction rate, precipitation uniformity, structural stability, and material properties, avoiding the excessive use of modifiers or precipitants, and reducing the cost and environmental burden.

[0050] In the present invention, the crystallization temperature is preferably 80 to 120 °C, and the crystallization time is preferably 4 to 10 h. More preferably, the crystallization temperature is 80 °C and the crystallization time is 8 h.

[0051] In the present invention, the drying temperature is preferably 50 to 80 °C, and the drying time is 5 to 8 h. More preferably, the drying temperature is 80 °C and the drying time is 8 h.

[0052] In some preferred embodiments of the present invention, after the crystallization slurry is filtered, the precipitate is washed with deionized water until the pH reaches 7.

[0053] In some other preferred embodiments of the present invention, after the precipitate is dried, it is ground and pulverized, and then passed through a 400-mesh sieve for standby.

[0054] The present invention provides a PVC functionalized additive prepared according to the above method.

[0055] The present invention also provides an application of a PVC functionalized additive in inhibiting the release of harmful substances in PVC and improving the biological safety of PVC. In some specific embodiments of the present invention, the harmful substance is DOTP.

[0056] The usage method of the PVC functionalized additive of the present invention is as follows:

[0057] Mix PVC, DOTP, and the PVC functionalized additive in proportion and stir evenly, stir mechanically for 30 min, and degas under vacuum until there are no obvious bubbles to obtain a PVC resin paste. Then, coat the PVC resin paste with a film applicator and plasticize it to obtain a soft PVC composite material.

[0058] The mass ratio of PVC, DOTP, and the PVC functionalized additive is 100:75:5; the plasticizing temperature is 180 °C and the plasticizing time is 3 min.

[0059] To further illustrate the present invention, the following examples are provided for detailed description. All the raw materials used in the following examples of the present invention are commercially available.

[0060] Example 1 A preparation method of a PVC functionalized additive includes the following steps:

[0061] S1. Add 70 mL of deionized water to a 250 mL three-necked round-bottom flask, and then add a specific amount (mol) of Mg(NO3)2·6H2O, La(NO3)3·6H2O, Ce(NO3)3·6H2O to obtain different solution A;

[0062]

[0063] S2. Add 0.18 mol of NaOH and 0.03 mol of Na2CO3 to 150 mL of deionized water to obtain a solution B with a pH of 11;

[0064] S3. Under N2 protection, slowly dropwise add solution B to different solution A, and stir at 80 °C for 8 h for coprecipitation;

[0065] S4. After coprecipitation, crystallize at 80 °C for 8 h to obtain a crystallized slurry;

[0066] S5. Filter the crystallized slurry and dry it at 80 °C for 8 h to obtain 5 kinds of MgLaCe-LDH Ae based PVC functionalized additives, which are respectively denoted as 20Mg10Ce-LDH Ae 、20Mg2.5La7.5Ce-LDH Ae 、20Mg5La5Ce-LDH Ae 、20Mg7.5La2.5Ce-LDH Ae, 20Mg10La-LDH Ae 。

[0067] Mix PVC, DOTP, and MgLaCe-LDH Ae based PVC functional additives in a mass ratio of 100:75:5, stir well, mechanically stir for 30 min, and vacuum degas until no obvious bubbles remain to obtain a PVC resin paste. Then, coat the PVC resin paste with a film applicator and plasticize it in a forced-air oven at 180 °C for 3 min to obtain 5 kinds of flexible PVC composites, denoted as 20Mg10Ce-LDH Ae / PVC, 20Mg2.5La7.5Ce-LDH Ae / PVC, 20Mg5La5Ce-LDH Ae / PVC, 20Mg7.5La2.5Ce-LDH Ae / PVC, 20Mg10La-LDH Ae / PVC.

[0068] Example 2

[0069] Same as Example 1, except that:

[0070] S5. Filter the crystallization slurry, wash the precipitate with deionized water until the pH is 7, and dry it at 80 °C for 8 h to obtain 5 kinds of MgLaCe-LDH Ne based PVC functional additives, denoted as 20Mg10Ce-LDH Ne , 20Mg2.5La7.5Ce-LDH Ne , 20Mg5La5Ce-LDH Ne , 20Mg7.5La2.5Ce-LDH Ne , 20Mg10La-LDH Ne 。

[0071] The 5 kinds of flexible PVC composites obtained are denoted as 20Mg10Ce-LDH Ne / PVC, 20Mg2.5La7.5Ce-LDH Ne / PVC, 20Mg5La5Ce-LDH Ne / PVC, 20Mg7.5La2.5Ce-LDH Ne / PVC, 20Mg10La-LDH Ne / PVC.

[0072] From Figure 1 A-B, it can be seen that 3695 cm -1 and 3450 cm -1The absorption peak at [specific position] is the stretching vibration peak of -OH and H2O molecules between layers, 1636 cm -1 The absorption peak at [specific position] is caused by the stretching vibration of -OH in crystalline H2O molecules. 500 - 750 cm -1 The characteristic peaks in the range are the vibration peaks of O-M-O bonds and M-O bonds (M = Mg 2+ , La 3+ , Ce 3+ ). The vibration peak at 1385 cm -1 and 789 cm -1 are the asymmetric stretching vibration peaks of C-O in CO3 2- . There is a certain shift towards lower wavenumbers, indicating that CO3 2- has been successfully intercalated into LDHs and has a strong hydrogen bond interaction with the interlayer water molecules of LDHs. Through the analysis of infrared absorption peaks, CO3 2- has been successfully intercalated into the interlayer of MgLaCe-based hydrotalcite. Figure 1 Figure C is the XRD diffraction pattern of MgLaCe-CO3-LDHs. From Figure 1 Figure B, it can be obtained that the sample shows characteristic diffraction peaks of LDHs at 2θ of 11.82°, 23.64°, 34.74°, 39.36°, 46.9°, 60.34° and 61.7°, which are the (003), (006), (009), (015), (018), (110) and (113) crystal planes respectively, and the diffraction peak shapes are relatively sharp and symmetric, and the baseline of the pattern is stable, indicating good interlayer regularity. Thus, it can be proved that the PVC functional additive - MgLaCe-CO3-LDHs has been successfully prepared. Among them, the characteristic peaks of 20Mg10La-LDH Ae and 20Mg7.5La2.5Ce-LDH Ae are sharper, indicating that the atomic arrangement in the above two kinds of hydrotalcite-like samples under alkaline conditions is more compact and the defects in the crystal lattice are reduced.

[0073] From Figure 2 it can be seen that the MgLaCe-CO3-LDHs of Example 1 and Example 2 both show a layered structure, and the layer structure sizes are uniform and regular, presenting the characteristic morphology of hydrotalcite, indicating the successful preparation of LDHs.

[0074] The biological safety evaluation of the PVC composite material is carried out as follows:

[0075] (1) Preparation of ordinary PVC film: The method is as follows: Mix PVC and DOTP in a mass ratio of 100:75 and stir evenly, mechanically stir for 30 min, perform vacuum degassing until there are no obvious bubbles to obtain a PVC resin paste, then coat the PVC resin paste with a coater, and plasticize it in a blast drying oven at 180 °C for 3 min to obtain an ordinary PVC film.

[0076] (2) Preparation of leaching solution: According to the provisions of GB16886.12, cut the PVC composite material (20Mg7.5La2.5Ce-LDH Ae ) and the ordinary PVC film with the same thickness into rectangles of 3 cm × 5 cm, place them completely statically in 50 mL of 0.9% physiological saline respectively, seal and store them, and then place them in a constant temperature oscillator at 37 °C and a rotation speed of 180 r / min for immersion for a total of 72 h. After the immersion is completed, suck out the leaching solutions of the PVC composite film respectively and store them in 50 mL centrifuge tubes to obtain leaching solutions. The leaching solution of the PVC composite material is denoted as C / PVC, and the leaching solution of the ordinary PVC film is denoted as PVC. The blank group uses 0.9% physiological saline.

[0077] (3) Acute toxicity experiment: Select 18 SD rats with a body weight of about 200 g and divide them into 3 treatment groups, with 6 SD rats in each group (3 female rats and 3 male rats). The evaluation method is as follows: Use the tail vein injection method to evenly inject the leaching solution into the SD rats at a speed of no more than 0.1 mL per second, and the injection dose is 50 mL / kg. The first group (blank group) is injected with physiological saline, the second group is injected with the PVC leaching solution, and the third group is injected with the C / PVC leaching solution. Immediately after the injection, pay attention to the immediate reaction of the SD rats, and observe general indicators such as the hair, mental state, toxicity reaction, and death number of the animals at 4, 24, 48, and 72 h after the injection. Sacrifice after 72 h, collect blood, and measure blood biochemical data. Strictly evaluate the reaction degree and specific symptoms of the SD rats in accordance with the regulations of our national standard.

[0078] The results of the biological safety evaluation are as Figure 3 shown.

[0079] As Figure 3 can be seen, the blood biochemical data of the D rats within 72 h after tail vein injection in the acute toxicity experiment. Compared with the pure PVC control group, the pure PVC group showed significant statistical differences in biochemical indicators such as alkaline phosphatase (ALP), total bilirubin (TBIL), urea, and free thyroxine (FT4), which implies that the potential harmful substances that may be released by pure PVC have an adverse effect on organisms.

[0080] However, in the PVC composite group, these biochemical parameters did not show significant changes and there were no statistical differences. This finding confirmed that adding non-toxic PVC functional additives to PVC could effectively inhibit the release of harmful substances, thus significantly improving the biological safety of the material.

[0081] To verify the source of toxicity in the pure PVC leaching solution, HPLC analysis was performed on the PVC leaching solution, and the analysis results are as Figure 3 shown in H.

[0082] As Figure 3 shown in H, the PVC filtrate contained DOTP, and the peak area was 1.67 mAU·S. However, DOTP was not detected in the filtrate of C / PVC. This further confirmed that the MgLaCe-CO3-LDHs of the present invention could effectively inhibit the migration of DOTP in PVC, provided the stability of DOTP, and confirmed that the PVC composite film prepared using MgLaCe-CO3-LDHs had the potential to be used as a biosafe material.

[0083] Example 3 A preparation method of a PVC functional additive includes the following steps:

[0084] S1. Add 70 mL of deionized water to a 250 mL three-necked round-bottom flask, and then add a specific amount (mol) of Mg(NO3)2·6H2O, La(NO3)3·6H2O, and Ce(NO3)3·6H2O to obtain different solution A;

[0085]

[0086]

[0087] S2. Add 0.18 mol of NaOH and 0.03 mol of Na2HPO4 to 150 mL of deionized water to obtain solution B with a pH of 11;

[0088] S3. Under N2 protection, dropwise add solution B to solution A, and stir at 90 °C for 4 h for coprecipitation;

[0089] S4. After coprecipitation, crystallize at 80 °C for 8 h to obtain a crystallized slurry;

[0090] S5. Filter the crystallized slurry and dry it at 80 °C for 8 h to obtain 5 kinds of MgLaCe-PO3-LDH Ae based PVC functional additives, which are respectively denoted as 20Mg10Ce-LDH Ae 、20Mg2.5La7.5Ce-LDH Ae 、20Mg5La5Ce-LDH Ae 、20Mg7.5La2.5Ce-LDHAe 、 20Mg10La-LDH Ae 。

[0091] Example 4

[0092] Same as Example 3, the differences are as follows:

[0093] S5. The crystallization slurry was filtered, washed with deionized water until the pH reached 7, and dried at 80 °C for 8 h to obtain MgLaCe-PO3-LDH Ne PVC functionalization aids based on MgLaCe, denoted as 20Mg10Ce-LDH Ne 、 20Mg2.5La7.5Ce-LDH Ne 、 20Mg5La5Ce-LDH Ne 、 20Mg7.5La2.5Ce-LDH Ne 、 20Mg10La-LDH Ne 。

[0094] It can be seen from Figure 4 that the MgLaCe-PO3-LDHs obtained in Example 3 and Example 4 both exhibit a layered structure, and the size of the layer structure is relatively uniform and regular, presenting the characteristic morphology of hydrotalcite, indicating the successful preparation of hydrotalcite.

[0095] It can be seen from Figure 5 A-B that the characteristic peaks in the range of 750 - 500 cm -1 are the vibration peaks of O-M-O bonds and M-O bonds (M = Mg 2+ , La 3+ , Ce 3 + ). The symmetric stretching vibration absorption peaks of P=O and P-O bonds, as well as the stretching vibration peak of P-OH (1056 cm -1 ) are in the range of 1200 - 1000 cm -1 , indicating the presence of phosphate and hydrogen phosphate in the sample. The peaks at 3698 cm -1 and 3450 cm -1 are the stretching vibration peaks of -OH and the H2O molecules between the layers, and the absorption peak at 1636 cm -1 is caused by the stretching vibration of -OH in the crystalline H2O molecules. In addition, the peaks at 1385 cm -1 and 789 cm -1 are the asymmetric stretching vibration peaks of C-O in CO3 2- , which may be generated by the adsorption of CO2 after sample preparation and exposure to air. Through the analysis of the infrared absorption peaks, PO3 2- has been successfully intercalated into the interlayer of MgLaCe-based hydrotalcite.

[0096] It can be seen fromFigure 5 As can be seen from C, the sample shows characteristic diffraction peaks of LDHs at 2θ of 11.58°, 23.24°, 34.52°, 39.08°, 46.62°, 60.1° and 61.46°, which are the (003), (006), (009), (015), (018), (110) and (113) crystal planes respectively. Moreover, the diffraction peak shapes are relatively sharp and symmetrical, and the baseline of the spectrum is stable, indicating good interlayer regularity. Thus, it can be proved that MgLaCe-LDHs have been successfully prepared. Among them, 20Mg10La-LDH Ne and 20Mg10Ce-LDH Ae have sharper characteristic peaks, indicating that the atomic arrangements in these LDHs samples are more compact and the defects in the crystal lattice are reduced.

[0097] To verify the biosafety of MgLaCe-PO3-LDHs (P-LDH), SD rats were orally administered 20Mg10Ce-LDH Ae suspension (200 mg / kg / d) by gavage for 28 days. Each milliliter of physiological saline contained 100 mg of P-LDH suspension. After 28 days, the organs of SD rats in all experiments were sampled, and H&E staining and pathological analysis were carried out. The results are as Figure 6 shown in A.

[0098] As Figure 6 can be seen from A, no obvious pathological changes were shown in the heart, liver, kidney, spleen, lung, brain, testis and epididymis of SD rats in the P-LDH group and the normal group. This further confirmed the environmental protection and safety of the P-LDH material, providing strong theoretical support for the application of P-LDH in PVC.

[0099] To verify the biosafety of the PVC composite material, a safety assessment method combining short-term and long-term was adopted. SPF clean-grade SD rats aged 4 - 6 weeks were selected. For the short-term safety assessment, the material leaching solution was evenly injected into the rats by tail vein injection at a speed not exceeding 0.1 mL / s, and the injection dose was 50 mL / kg. Among them, the leaching solution group of the PVC composite material (20Mg10Ce-LDH Ae / PVC) was denoted as P-LDH / PVC, and the leaching solution group of the ordinary PVC material was denoted as PVC. After 3 days, detailed pathological analysis of each organ of SD rats was carried out by H&E staining. The results are as Figure 6 shown in B.

[0100] As Figure 6As can be seen from B, the pathological analysis of the short-term safety evaluation of MgLaCe-PO3-LDHs / PVC (P-LDH / PVC) in SD rats (magnified 20 times, the scale bar in the figure is 50 μm). From Figure 6 It can be clearly observed from B that significant lesions were shown in the pure PVC group (indicated by the red arrows in the figure). Specifically, the myocardial structure was abnormal, and the myocardial space was significantly enlarged; the hepatocytes were significantly hyperplastic, the hepatic sinusoids were slightly widened, there was infiltration of inflammatory cells in the portal area, the lymphocytes increased, and the inflammatory cells appeared inside the hepatocytes, showing the changes of interface hepatitis; the glomeruli were significantly atrophied; the alveolar wall septum was widened; the density of glial cells increased, accompanied by cellular atypia; the sperm were significantly reduced. Compared with the PVC group, the overall structures of all tissues in the blank group and the P-LDH / PVC group were basically normal, there was no aggregation of inflammatory cells in the tissues, and no obvious lesions occurred. This indicates that the leaching solution of pure PVC caused damage to the organs of SD rats to a certain extent, probably because the PVC membrane has poor migration resistance, and the toxicity comes from the migration of DOTP in the PVC film into the PVC leaching solution. The P-LDH / PVC group was close to the blank group, which further proved that adding hydrotalcite to PVC can inhibit the release of toxicity to a certain extent. These findings provide important experimental support for comprehensively understanding the safety of PVC composite membranes.

[0101] To verify the long-term safety of MgLaCe-PO3-LDH / PVC (P-LDH / PVC), SD rats were orally administered with the P-LDH / PVC leaching solution (50 mg / kg / d) by gavage. The preparation method of the leaching solution was the same as that described above, and the time lasted for 28 days. Subsequently, detailed pathological analysis was performed on various organs of the SD rats (magnified 20 times, the scale bar in the figure is 50 μm). According to Figure 6From the observations of Group C, it can be clearly seen that obvious lesions occurred in the pure PVC group, as indicated by the red arrows in the figure. The specific manifestations were as follows: the myocardial interstitium was significantly enlarged, accompanied by inflammatory cell hyperplasia; the hepatocytes showed atypical hyperplasia; the glomerular structure was blurred; the alveolar wall septum was widened, losing the normal alveolar structure; the glial cells showed dense hyperplasia; in contrast, the overall structures of all tissues in the blank group and the P-LDH / PVC group were basically normal, and no aggregation of inflammatory cells or obvious lesions were observed. This indicates that the leaching solution of pure PVC caused damage to the organs of SD rats to a certain extent, mainly because the migration performance of the PVC film was poor, and a large amount of DOTP migrated from the PVC film into the extraction solution. On the contrary, the pathological sections of the P-LDH / PVC group were similar to those of the blank group, further confirming that the addition of P-LDHs to PVC could inhibit the release of toxic substances to a certain extent. Through the long-term safety evaluation study of the PVC composite film, the importance of P-LDH in the application of PVC was affirmed, providing data support for the sustainable development of the PVC composite film.

[0102] The above-described embodiments merely represent several implementation manners of the present invention. Their descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A preparation method of a PVC functional additive, characterized in that, It includes the following steps: S1. Add the precursor into deionized water to obtain solution A; S2. Add the modifier and the precipitant into deionized water to obtain solution B; S3. Under stirring conditions, drop solution B into solution A for coprecipitation; S4. Conduct crystallization after coprecipitation to obtain a crystallized slurry; S5. Filter and dry the crystallized slurry to obtain a PVC functional additive; The modifier is Na2CO3 or Na2HPO3, and the precipitant is NaOH.

2. The preparation method according to claim 1, characterized in that, The precursor is at least two of magnesium salt, lanthanum salt and cerium salt.

3. The preparation method according to claim 2, characterized in that, The magnesium salt, lanthanum salt and cerium salt are at least two of Mg(NO3)2·6H2O, La(NO3)3·6H2O, Ce(NO3)3·6H2O.

4. The preparation method according to claim 1, characterized in that, The precursor is composed of Mg(NO3)2·6H2O, La(NO3)3·6H2O, Ce(NO3)3·6H2O in a molar ratio of 0.04:(0 - 0.1):(0 - 0.1).

5. The preparation method according to claim 1, characterized in that, The concentration of the precursor in solution A is 0.06mol / 70mL.

6. The preparation method according to claim 1, wherein, In solution B, the concentration of the modifier is 0.03mol / 150mL, and the concentration of the precipitant is 0.18mol / 150mL.

7. The preparation method according to claim 1, characterized in that, The volume ratio of solution A to solution B is 7:15, the coprecipitation temperature is 80°C - 120°C, and the coprecipitation time is 4 - 8h.

8. The preparation method according to claim 1, wherein, The crystallization temperature is preferably 80°C, and the crystallization time is 8h.

9. A PVC functional additive, characterized in that, Prepared by the method according to any one of claims 1 - 8.

10. Application of a PVC functional additive in inhibiting the release of harmful substances in PVC and enhancing the biosafety of PVC, characterized in that, The PVC functional additive is the PVC functional additive prepared by the method according to any one of claims 1 - 8 or the PVC functional additive according to claim 9.

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