Method for modifying interlayer perchlorate radical intercalation of hydrotalcite

Abstract

The invention discloses a method for modifying hydrotalcite with perchlorate, and belongs to the field of hydrotalcite modification, magnesium-aluminum carbonate hydrotalcite is subjected to high-temperature calcination in a muffle furnace to obtain a composite metal oxide, the composite metal oxide and a sodium perchlorate solution are subjected to a reaction, and magnesium-aluminum perchlorate hydrotalcite is obtained after the reaction is completed. Compared with a conventional direct adsorption method, the method has the advantages that the composite metal oxide is obtained by calcining the hydrotalcite, and the hydrotalcite has a memory effect, so that the re-hydrated hydrotalcite has more surface adsorption sites, and perchlorate radicals can be more effectively adsorbed on the surface of the hydrotalcite; the hydrotalcite obtained by intercalation modification through a calcination remodeling method has more lasting long-term anti-aging performance in PVC (Polyvinyl Chloride).

Description

Technical Field

[0001] The invention relates to a method for modifying hydrotalcite, in particular to a method for modifying hydrotalcite with perchlorate, and belongs to the field of hydrotalcite modification. Background Art

[0002] PVC has good mechanical properties and corrosion resistance, and can be made into hard, semi-hard, and soft products to meet the processing needs of PVC products in all aspects.

[0003] However, PVC also has disadvantages such as being difficult to process, releasing HCL gas due to molecular chain breakage during high-temperature processing, and having poor thermal stability.

[0004] Heat stabilizers are essential stabilizing agents in the processing of polyvinyl chloride (PVC) products, which make PVC products have good long-lasting weather resistance during processing and storage. Heat stabilizers need to be added during the processing of PVC. Commonly used heat stabilizers in PVC processing include lead salts, metal soaps, and organic tin. With the increasing calls for environmental protection at home and abroad, the research on using hydrotalcite as a stabilizer in PVC is becoming more and more important, and the modification of hydrotalcite to extend its anti-aging time in PVC has attracted more and more attention. Summary of the invention

[0005] In view of this, the present invention provides a method for modifying hydrotalcite with perchlorate, which improves the long-term anti-aging performance of hydrotalcite in PVC at a relatively low cost.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for perchlorate-modified hydrotalcite, comprising the following steps:

[0008] (1) calcining magnesium aluminum carbonate hydrotalcite in a muffle furnace to obtain a composite metal oxide;

[0009] (2) The composite metal oxide is mixed with a sodium perchlorate solution to react to obtain an interlayer perchlorate intercalation modified hydrotalcite.

[0010] On the basis of the above technical solution, the present invention has the following further limitations:

[0011] Furthermore, in step (1), the calcination temperature is 300°C-550°C, and the calcination time is 2h-5h. Preferably, the calcination temperature is 500°C, and the calcination time is 4h.

[0012] Furthermore, in step (2), the solid-liquid ratio of the composite metal oxide to the solvent in the sodium perchlorate solution is 1:10-30, preferably, the solid-liquid ratio is 1:20.

[0013] Furthermore, in step (2), the reaction time is 8-18 hours, and the reaction temperature is 50-90°C. Preferably, the reaction time is 12 hours, and the reaction temperature is 60°C.

[0014] The beneficial effect of the present invention lies in that, compared with the conventional direct adsorption method, the present invention obtains the composite metal oxide by calcining the hydrotalcite, utilizes the memory effect of the hydrotalcite, makes the rehydrated hydrotalcite have more surface adsorption sites, and makes the perchlorate ion more effectively adsorbed on the surface of the hydrotalcite. Experiments show that the long-term anti-aging performance of the hydrotalcite obtained by intercalation modification through the calcination and reshaping method in PVC is more durable. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a Fourier infrared spectrum of each hydrotalcite in Example 5 of the present invention;

[0016] Figure 2 is the X-ray diffraction pattern of each hydrotalcite in Example 5 of the present invention;

[0017] Figure 3 TG-DTG diagram of each hydrotalcite in Example 5 of the present invention;

[0018] Figure 4 It is the SEM electron microscope scanning image of each hydrotalcite in Example 5 of the present invention;

[0019] Figure 5 is the EDS spectrum of each hydrotalcite in Example 5 of the present invention;

[0020] Figure 6 This is a photo of the aging test results of the PVC material sample in Example 5 of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1

[0023] The method for modifying hydrotalcite with perchlorate comprises the following steps:

[0024] (1) calcining magnesium aluminum carbonate hydrotalcite in a muffle furnace at 500° C. for 4 h to obtain a composite metal oxide;

[0025] (2) The composite metal oxide is mixed with a sodium perchlorate solution, wherein the solid-liquid ratio of the composite metal oxide to the solvent in the sodium perchlorate solution is 1:20. After mixing, the mixture is reacted at 60° C. for 12 hours to obtain an interlayer perchlorate intercalation modified hydrotalcite.

[0026] Example 2

[0027] The method for modifying hydrotalcite with perchlorate comprises the following steps:

[0028] (1) calcining magnesium aluminum carbonate hydrotalcite in a muffle furnace at 300° C. for 2 h to obtain a composite metal oxide;

[0029] (2) The composite metal oxide is mixed with a sodium perchlorate solution, wherein the solid-liquid ratio of the composite metal oxide to the solvent in the sodium perchlorate solution is 1:10. After mixing, the mixture is reacted at 50° C. for 8 hours to obtain an interlayer perchlorate intercalation modified hydrotalcite.

[0030] Example 3

[0031] The method for modifying hydrotalcite with perchlorate comprises the following steps:

[0032] (1) calcining magnesium aluminum carbonate hydrotalcite in a muffle furnace at 550° C. for 5 h to obtain a composite metal oxide;

[0033] (2) The composite metal oxide is mixed with a sodium perchlorate solution, wherein the solid-liquid ratio of the composite metal oxide to the solvent in the sodium perchlorate solution is 1:30. After mixing, the mixture is reacted at 90° C. for 18 hours to obtain an interlayer perchlorate intercalation modified hydrotalcite.

[0034] Example 4

[0035] The method for modifying hydrotalcite with perchlorate comprises the following steps:

[0036] (1) calcining magnesium aluminum carbonate hydrotalcite at 400° C. in a muffle furnace for 4 h to obtain a composite metal oxide;

[0037] (2) The composite metal oxide is mixed with a sodium perchlorate solution, wherein the solid-liquid ratio of the composite metal oxide to the solvent in the sodium perchlorate solution is 1:15. After mixing, the mixture is reacted at 80° C. for 15 hours to obtain an interlayer perchlorate intercalation modified hydrotalcite.

[0038] Example 5

[0039] (1) Take commercially available magnesium aluminum carbonate hydrotalcite, denoted as hydrotalcite A;

[0040] (2) Weigh 1.5 g of sodium perchlorate and dissolve it in 200 g of deionized water. Stir evenly, directly add 16.7 g of magnesium aluminum carbonate hydrotalcite (hydrotalcite A), stir at high speed for 12 h at 60 ° C, wash, dry, and sieve. The product is recorded as hydrotalcite B;

[0041] (3) Weigh 1.5 g of sodium perchlorate and dissolve it in 200 g of deionized water, stir it evenly, add 10 g of the composite metal oxide obtained by calcining 16.7 g of magnesium aluminum carbonate hydrotalcite (hydrotalcite A), stir it at high speed at 60 ° C for 12 h, wash, dry, and sieve, and the product is recorded as hydrotalcite C;

[0042] (4) 1.1 g of each of hydrotalcite A, hydrotalcite B and hydrotalcite C were mixed with 100 g of PVC and 0.9 g of zinc stearate, and 50 g of DOTP was added. The mixture was milled at 170° C. for 5 min to obtain a PVC material sample with a thickness of 0.8 mm.

[0043] (5) The performance of three types of hydrotalcite was tested respectively. The Fourier infrared spectra were as follows: Figure 1 ,Depend on Figure 1 It can be seen that compared with hydrotalcite B, hydrotalcite C obtained by calcination and then hydrothermal treatment has a more obvious stretching vibration peak of the C lO bond;

[0044] like Figure 2 In the X-ray diffraction diagram, A, B, and C are all characteristic peaks of hydrotalcite, and only obvious characteristic peaks of MgO are observed in A-LDO. This indicates that the crystal structure of hydrotalcite A has been destroyed after calcination, A-LDO forms a new crystal structure, and B and C obtained by hydrothermal treatment on the basis of A-LDO are both hydrotalcite.

[0045] like Figure 3 , it can be seen from the thermogravimetric DTG curves of A, B, and C that with the increase of the perchlorate content adsorbed on the surface of hydrotalcite, the hydroxyl heat loss peak temperature in the range of 300℃-330℃ moves to the high temperature zone, while the carbonate heat loss peak temperature in the range of 400℃-450℃ moves to the low temperature zone. The TG curve changes with small fluctuations, indicating that this modification method has little effect on the overall weight loss ratio of hydrotalcite.

[0046] SEM scanning electron microscope image Figure 4 ,Depend on Figure 4 It can be seen that the specific surface areas (m 2 / g) are A: 22.0379, B: 21.8284, C: 53.7132, indicating that hydrotalcite C has a larger specific surface area and stronger adsorption points than hydrotalcite A; EDS spectra are shown in Figure 5 , Figure 5 The content of each substance is shown in Table 1 below:

[0047] Table 1 Content of each substance in EDS spectrum

[0048]

[0049] (6) The three types of hydrotalcite were cut into 9 small pieces of uniform size (a total of 27 pieces) and subjected to aging test in an aging chamber at a test temperature of 190°C. One piece was taken out every 15 minutes for observation and recording. The results are as follows: Figure 6 As shown by Figure 6 It can be seen that the hydrotalcite obtained by surface modification through calcination and reshaping method has more durable long-term anti-aging performance in PVC.

Claims

1. A method for perchlorate-modified hydrotalcite, characterized in that: Here are the steps: (1) calcining magnesium aluminum carbonate hydrotalcite in a muffle furnace to obtain a composite metal oxide; (2) The composite metal oxide is mixed with a sodium perchlorate solution to react to obtain an interlayer perchlorate intercalation modified hydrotalcite.

2. The method for perchlorate-modified hydrotalcite according to claim 1, characterized in that: The calcination temperature in step (1) is 300° C.-550° C., and the calcination time is 2 h-5 h.

3. The method for perchlorate-modified hydrotalcite according to claim 1, characterized in that: In step (2), the solid-to-liquid ratio of the composite metal oxide to the solvent in the sodium perchlorate solution is 1:10-30.

4. The method for perchlorate-modified hydrotalcite according to claim 1, characterized in that: The reaction time in step (2) is 8-18 hours, and the reaction temperature is 50-90°C.

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