Intercalated hydrotalcite as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of modified polypropylene plastics, and discloses intercalated hydrotalcite as well as a preparation method and application thereof, and is characterized in that the preparation method comprises a mode I or a mode II; the first mode comprises the following steps: mixing the mixed solution A and the mixed solution B, and reacting in the presence of protective gas to obtain intercalated hydrotalcite; the second mode is as follows: in the presence of protective gas, the mixed solution A and the mixed solution B are contacted and react to obtain intercalated hydrotalcite; wherein in the first mode and the second mode, the mixed solution A is a mixed solution of metal salt and a modifier; the mixed solution B is a mixed solution of a precipitator and a functional object. According to the preparation method disclosed by the invention, the corresponding surface organic modified LDHs are directly obtained in one step, the agglomeration tendency in the storage and use processes is reduced, and the dispersity of the intercalated hydrotalcite is improved.

Description

Technical Field

[0001] This invention relates to the field of modified polypropylene plastics technology, and more specifically, to an intercalated hydrotalcite, its preparation method, and its application. Background Technology

[0002] Polypropylene (PP) is a widely used thermoplastic. Due to its low processing cost, good mechanical properties, non-toxicity, and ease of processing, it is widely used in construction, food packaging, medical equipment, toys, and many other fields. As a semi-crystalline polymer, the crystallization rate and crystal size of PP significantly affect the mechanical, optical, and thermal properties of the finished products. With the increasing demand for functional PP, research on PP modification has become increasingly important. Adding nucleating agents to PP is a common method of modification. Nucleating agents promote PP crystallization by providing nuclei, thereby increasing the crystallization temperature and rate. Commonly used nucleating agents include inorganic nucleating agents such as talc, silica, and mica, and organic nucleating agents such as aryl phosphates and sorbitol. However, there are few reports on reducing the PP crystallization temperature and delaying the PP crystallization rate. CN107835841 B designs a crystallization-delaying polymer composition consisting of an azazine dye and an ionic liquid, but this method affects the optical properties of the finished product, limiting its application in many fields.

[0003] Layered double hydroxides (LDHs) are an important class of anionic inorganic layered materials, whose chemical composition can be represented as: [M 2+ 1-x M 3+ x [(OH)2](A n- ) x / n ·mH2O is composed of divalent and trivalent metal cations M 2+ and M 3+ Main layer and interlayer anion guest A n- LDHs are hexagonal layered compounds similar to graphite, assembled in an ordered manner. Due to the tunable nature of their host layer chemical composition, guest cell types and quantities, intralayer elastic space, and host-guest interactions, LDHs have been extensively studied in fields such as catalytic materials, functional membrane materials, adsorbent materials, and functional additives. Faced with diverse reaction environments in various fields, surface-positively charged hydrophilic LDHs are no longer sufficient. Therefore, surface modification of LDHs is often necessary to alter their surface charge properties and affinity for reactants, thereby obtaining high-performance LDH functional materials. Summary of the Invention

[0004] The purpose of this invention is to provide an intercalated hydrotalcite, its preparation method, and its application. The intercalated hydrotalcite of this invention has hydrophobic surface properties, which reduces the tendency of agglomeration during storage and use, and improves the dispersibility of the intercalated hydrotalcite. The intercalated hydrotalcite of this invention can be well dispersed in a polymer matrix, which lowers the crystallization temperature of the polymer. Therefore, by adjusting the crystallization temperature and crystallization rate of the polymer during processing and application, the processing stability, mechanical properties, and optical properties of the product can be controlled.

[0005] The first aspect of the present invention provides a method for preparing intercalated hydrotalcite, the method comprising: method one or method two;

[0006] Method 1 involves mixing mixed solution A and mixed solution B, and then reacting them in the presence of a protective gas to obtain the intercalated hydrotalcite.

[0007] Method two involves contacting and reacting mixed solution A and mixed solution B in the presence of a protective gas to obtain the intercalated hydrotalcite.

[0008] In both methods one and two: the mixed solution A is a mixed solution of metal salt and modifier; the mixed solution B is a mixed solution of precipitant and functional object.

[0009] A second aspect of the present invention provides an intercalated hydrotalcite prepared by the above-described preparation method.

[0010] A third aspect of the present invention provides the application of the above-mentioned intercalated hydrotalcite as an additive to reduce the crystallization temperature of polymers.

[0011] The technical solution of the present invention has the following beneficial effects:

[0012] (1) The preparation method of the present invention directly obtains the corresponding surface organic modified LDHs in one step, which reduces the tendency of agglomeration during storage and use and improves the dispersibility of intercalated hydrotalcite.

[0013] (2) The intercalated structure hydrotalcite of the present invention can be well dispersed in the polymer matrix, thereby reducing the polymer crystallization temperature by 5-10°C. The average size of the spherulites during the isochronous cooling crystallization process is 10-50 μm. Thus, by adjusting the crystallization temperature and crystallization rate of the polymer during processing and application, the processing stability, mechanical properties and optical properties of the product can be controlled.

[0014] (3) The preparation method of the present invention has the advantages of simple operation, low cost and continuous large-scale production.

[0015] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0016] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0017] Figure 1 The XRD pattern of the intercalated hydrotalcite according to Embodiment 1 of the present invention is shown;

[0018] Figure 2 The FTIR spectrum of the intercalated hydrotalcite according to Embodiment 1 of the present invention is shown;

[0019] Figure 3 A 500x polarized microscope image of polypropylene containing intercalated hydrotalcite according to Embodiment 1 of the present invention is shown. Detailed Implementation

[0020] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0021] The first aspect of the present invention provides a method for preparing intercalated hydrotalcite, the method comprising: method one or method two;

[0022] Method 1 involves mixing mixed solution A and mixed solution B, and then reacting them in the presence of a protective gas to obtain the intercalated hydrotalcite.

[0023] Method two involves contacting and reacting mixed solution A and mixed solution B in the presence of a protective gas to obtain the intercalated hydrotalcite.

[0024] In both methods one and two: the mixed solution A is a mixed solution of metal salt and modifier; the mixed solution B is a mixed solution of precipitant and functional object.

[0025] In this invention, the mixing in Method 1 can employ commonly used mixing methods in the art, such as mixing using a colloid mill. The contacting in Method 2 can employ conventional contacting methods in the art, such as contacting by dropping.

[0026] In this invention, preferably, the protective gas is an inert gas, and more preferably at least one of nitrogen, argon and helium.

[0027] In this invention, the preparation method of the intercalated hydrotalcite differs from the traditional method of first preparing LDHs and then modifying them. This method directly prepares a solution with the modifier and the metal salt, directly obtaining the corresponding surface-organically modified LDHs in one step. Because the prepared modified LDHs have hydrophobic surface properties, the tendency to agglomerate during storage and use is reduced, improving the dispersibility of the intercalated hydrotalcite.

[0028] According to the present invention, preferably, the metal salt includes divalent metal salts and trivalent metal salts;

[0029] The divalent metal ion of the divalent metal salt is Mg. 2+ Zn 2+ Co 2+ Ni 2+ Ca 2+ Fe 2+ and Cu 2+ At least one of them;

[0030] The trivalent metal ion of the trivalent metal salt is Al. 3+ Co 3+ Ti 3+ Fe 3+ and Cr 3+ At least one of them;

[0031] The divalent metal ion M of the metal salt 2+ With trivalent metal ions M 3+ The molar ratio is (2-4):1;

[0032] Preferably, the metal salt is an inorganic metal salt.

[0033] In this invention, for example, the divalent metal ion of the divalent metal salt is Mg. 2+ Zn 2+ Co 2+ Ni 2+ Ca 2+ Fe 2+ and Cu 2+ One or two of the following; the trivalent metal ion of the trivalent metal salt is Al. 3+ Co 3+ Ti 3+ Fe 3+ and Cr 3+ One or two of them.

[0034] According to the present invention, preferably, the precipitant is at least one selected from NaOH, KOH, ammonia, urea and hexamethylenetetramine.

[0035] In this invention, NaOH is NaOH powder and KOH is KOH powder.

[0036] According to the present invention, preferably, the modifier is at least one selected from sodium dodecyl sulfate (SDS), sodium dodecyl sulfonate, sodium oleate, sodium stearate, and disodium ethylenediaminetetraacetate.

[0037] According to the present invention, preferably, the functional object is an antioxidant; the antioxidant is preferably a hindered phenolic compound, more preferably at least one selected from β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, sodium β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid, sodium β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate, 3,5-di-tert-butyl-4-hydroxybenzoic acid, and sodium 3,5-di-tert-butyl-4-hydroxybenzoate.

[0038] According to the present invention, preferably, the molar ratio of the modifier to the metal salt is 1:(10-200);

[0039] The molar ratio of the metal salt to the precipitant is 1:(1.5-3);

[0040] The molar ratio of the functional object to the precipitant is 1:(1-4);

[0041] In the mixed solution A, the divalent metal ions M of the metal salt 2+ The molar concentration is 0.01–1 mol / L;

[0042] In the mixed solution B, the molar concentration of the functional guest is 0.01 to 1 mol / L.

[0043] According to the present invention, preferably, in methods one and two: the reaction temperature is 25-180°C and the time is 1-12 hours;

[0044] In Method 2, the pH value of the reaction system is controlled to be 9.5–10.5.

[0045] A second aspect of the present invention provides an intercalated hydrotalcite prepared by the above-described preparation method.

[0046] A third aspect of the present invention provides the application of the above-mentioned intercalated hydrotalcite as an additive to reduce the crystallization temperature of polymers.

[0047] According to the present invention, preferably, the polymer is a polypropylene resin.

[0048] The present invention is further illustrated by the following examples:

[0049] In the following examples and comparative examples: the twin-screw extruder used was purchased from Wemer & Pfleiderer GmbH, Germany, model ZSK25.

[0050] In the following examples and comparative examples, the NaOH used was NaOH powder.

[0051] Example 1

[0052] Step 1: Dissolve 0.1 mol Mg(NO3)2 and 0.05 mol Al(NO3)3 in 180 mL of deionized water, and add 20 mL of 0.22 mol / L sodium stearate ethanol solution. Stir for 10 min to prepare mixed solution A; dissolve 0.3 mol NaOH and 0.12 mol DBHP (β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid) in 200 mL of deionized water to prepare mixed solution B.

[0053] Step 2: Pour solutions A and B from Step 1 into a colloid mill with a slit width of 0.02 mm and a rotation speed of 1500 rpm for mixing. After 5 min of circulation, transfer the slurry to a flask and continue to react in a water bath at 70 °C under a nitrogen atmosphere for 6 h. After the reaction is complete, centrifuge and wash all the slurries several times. The resulting product is dried at 60 °C and then ground into powder (intercalated hydrotalcite).

[0054] Step 3: The surface-organic modified composite metal hydroxide (intercalated hydrotalcite) prepared in Step 2 and polypropylene resin PPH-T03 (produced by Sinopec Zhenhai Refining & Chemical Co., Ltd.) are weighed and mixed according to the formula, and then fed into a twin-screw extruder. The barrel temperature is 205℃ and the screw speed is 150r / min. The mixture is co-extruded, and the extruded strip is cooled by a water tank and then granulated to obtain polypropylene granules containing intercalated hydrotalcite. The amount of surface-organic modified composite metal hydroxide is 0.6 parts by weight, and the amount of polypropylene resin is 100 parts by weight.

[0055] Example 2:

[0056] Step 1: Dissolve 0.1 mol Mg(NO3)2 and 0.05 mol Al(NO3)3 in 100 mL of deionized water, and add 20 mL of 0.22 mol / L sodium stearate ethanol solution. Stir for 10 min to prepare mixed solution A; dissolve 0.3 mol NaOH and 0.12 mol DBHP in 200 mL of deionized water to prepare mixed solution B.

[0057] Step 2: Under a nitrogen atmosphere, solutions A and B from Step 1 were added dropwise to a flask containing 50 mL of deionized water using a double-drop method. The pH of the solution in the flask was maintained between 9.5 and 10.5 by controlling the dropping rate of mixed solution B. Solutions A and B were added dropwise over 20 minutes. The suspension was then reacted at 60°C for 4 hours. After the reaction, the slurry was removed and centrifuged and washed several times. The resulting product was dried at 60°C and then ground into powder (intercalated hydrotalcite).

[0058] Step 3: Same as step 3 in Example 1, to obtain polypropylene granules containing intercalated hydrotalcite.

[0059] Example 3:

[0060] Step 1: Dissolve 0.1 mol Co(NO3)2 and 0.05 mol Fe(NO3)3 in 180 mL of deionized water, and add 20 mL of 0.22 mol / L sodium stearate ethanol solution. Stir for 10 min to prepare mixed solution A; dissolve 0.3 mol NaOH and 0.12 mol DBHP in 200 mL of deionized water to prepare mixed solution B.

[0061] Step 2: Pour solutions A and B from Step 1 into a colloid mill with a slit width of 0.02 mm and a rotation speed of 1500 rpm for mixing. After 5 min of circulation, transfer the slurry to a flask and continue to react in a water bath at 70 °C under a nitrogen atmosphere for 6 h. After the reaction is complete, centrifuge and wash all the slurries several times. The resulting product is dried at 60 °C and then ground into powder (intercalated hydrotalcite).

[0062] Step 3: Same as step 3 in Example 1, to obtain polypropylene granules containing intercalated hydrotalcite.

[0063] Example 4:

[0064] Step 1: Dissolve 0.1 mol Mg(NO3)2 and 0.05 mol Al(NO3)3 in 180 mL of deionized water, and add 20 mL of 0.22 mol / L sodium dodecyl sulfate ethanol solution to prepare mixed solution A by stirring for 10 min; dissolve 0.3 mol NaOH and 0.12 mol DBHP in 200 mL of deionized water to prepare mixed solution B.

[0065] Step 2: Under a nitrogen atmosphere, solutions A and B from Step 1 were added dropwise to a flask containing 50 mL of deionized water using a double-drop method. The pH of the solution in the flask was maintained between 9.5 and 10.5 by controlling the dropping rate of mixed solution B. Solutions A and B were added dropwise over 20 minutes. The suspension was then reacted at 60°C for 4 hours. After the reaction, the slurry was removed and centrifuged and washed several times. The resulting product was dried at 60°C and then ground into powder (intercalated hydrotalcite).

[0066] Step 3: Same as step 3 in Example 1, to obtain polypropylene granules containing intercalated hydrotalcite.

[0067] Comparative Example 1:

[0068] Polypropylene resin PPH-T03 (produced by Sinopec Zhenhai Refining & Chemical Co., Ltd.) was added to a twin-screw extruder at a barrel temperature of 205℃ and a screw speed of 150r / min for co-extrusion. The extruded strip was cooled by a water tank and then pelletized.

[0069] Comparative Example 2:

[0070] Step 1: Dissolve 0.1 mol Mg(NO3)2 and 0.05 mol Al(NO3)3 in 180 mL of deionized water, and add 20 mL of 0.22 mol / L sodium stearate ethanol solution. Stir for 10 min to prepare mixed solution A; dissolve 0.3 mol NaOH and 0.12 mol Na2CO3 in 200 mL of deionized water to prepare mixed solution B.

[0071] Step 2 is the same as step 2 in Example 1.

[0072] Step 3 is the same as step 3 in Example 1, to obtain polypropylene granules containing intercalated hydrotalcite.

[0073] Comparative Example 3:

[0074] Step 1: Dissolve 0.1 mol Mg(NO3)2 and 0.05 mol Al(NO3)3 in 200 mL of deionized water and stir for 10 min to prepare mixed solution A; dissolve 0.3 mol NaOH and 0.12 mol DBHP in 200 mL of deionized water to prepare mixed solution B.

[0075] Step 2: Same as step 2 in Example 1.

[0076] Step 3 is the same as step 3 in Example 1, to obtain polypropylene granules containing intercalated hydrotalcite.

[0077] Comparative Example 4:

[0078] Step 1: Dissolve 80 mmol DBHP and 80 mmol NaOH in 200 mL of deionized water to obtain an alkaline solution of antioxidant, and purge with nitrogen; dissolve 80 mmol Mg(NO3)2·6H2O and 40 mmol Al(NO3)3·9H2O in 100 mL of deionized water to obtain a mixed salt solution; dissolve 240 mmol NaOH in 100 mL of deionized water to prepare an alkaline solution.

[0079] Step 2: Place the alkaline solution of the antioxidant prepared in Step 1 into a four-necked flask, and place the flask in a water bath. Adjust the temperature of the water bath to 25°C and the rotation speed of the magnetic stirrer to 400 rpm. Under a nitrogen atmosphere, add the salt solution and alkaline solution prepared in Step 1 dropwise into the flask through a constant pressure separatory funnel at a flow rate of 0.2 mL / s. Maintain the pH of the solution between 9 and 10 using a pH meter. React for 6 hours to obtain a hydrotalcite slurry. Centrifuge the slurry and wash it with deionized water until the supernatant is neutral.

[0080] Step 3: Disperse the hydrotalcite (LDHs) prepared in Step 2 in deionized water, then add sodium stearate (6% by mass of LDHs) and mix and stir. React at 70°C for 4 hours. Centrifuge the above slurry and wash, dry and grind it with deionized water to obtain the modified hydrotalcite sample.

[0081] Step 4 is the same as step 3 in Example 1, to obtain polypropylene granules containing intercalated hydrotalcite.

[0082] Test Example 1

[0083] The intercalated hydrotalcite prepared in Example 1 was tested, and the specific test methods and results are as follows:

[0084] X-ray diffraction (XRD): scanning rate 10° / min, scanning range 2°~70°. The crystal structure of the samples was characterized using an XRD-6000 X-ray powder diffractometer manufactured by Shimadzu Corporation, Japan.

[0085] Fourier transform infrared spectroscopy (FTIR): in the range of 4000–400 cm⁻¹ -1 Scanning. Fourier transform infrared spectrometer, purchased from Bruker GmbH, Germany, model VECTOR 22.

[0086] Method for determining the crystal morphology of polypropylene materials: An OLYMPUS USB X51 polarizing microscope (OLYMPUS, Japan) was used. The sample was heated from room temperature to 220°C at a rate of 50°C / min, held at that temperature for 3 min, and then cooled to 50°C at a rate of 10°C / min. The isochronous cooling crystallization process was observed, and the crystal morphology of the sample was recorded. The diameter of the spherulites was measured and statistically analyzed to obtain the average diameter (based on 100 sample points).

[0087] Figure 1 The image shows the XRD pattern of the surface-organic modified composite metal hydroxide (intercalated hydrotalcite) prepared according to Example 1 of the present invention. Figure 2 The image shows the FTIR spectrum of the surface-organic modified composite metal hydroxide (intercalated hydrotalcite) prepared according to Example 1 of the present invention. Figure 3 The image shows a polarized light microscope image of the isorheological cooling crystallization process of polypropylene containing intercalated hydrotalcite prepared according to Example 1 of the present invention. The above measurements show that the obtained sample exhibits characteristic LDH crystal plane diffraction peaks (003), (006), and (009), as well as alkyl stretching vibration peaks, indicating that sodium stearate-modified LDHs were successfully prepared. Adding these to the polypropylene material lowers the polypropylene crystallization temperature and regulates the size of polypropylene spherulites.

[0088] Test Example 2

[0089] Polypropylene granules containing intercalated hydrotalcite obtained in Examples 1-4 and Comparative Examples 1-4 were added to an injection molding machine for injection molding to obtain injection molded samples. The temperatures of each section of the injection molding machine were 180℃, 190℃, 210℃, 210℃, and 200℃, the holding pressure was 50MPa, the holding time was 60s, and the cooling time was 10s. The performance of the obtained injection molded samples was tested, and the specific test results are shown in Table 1. Among them, the impact strength was determined according to the method specified in GB / T 1043.1-2008; the tensile strength was determined according to the method specified in GB / T 1040.2-2022; the crystallization temperature of polypropylene containing intercalated hydrotalcite was determined using the Diamond DSC of Perkin Elmer, USA. Weigh approximately 5 mg of the sample. Under a N2 atmosphere, heat the sample from 50°C to 230°C at a rate of 10°C / min, hold the temperature for 3 minutes to eliminate the influence of its thermal history, then cool it down to 50°C at a rate of 10°C / min, hold the temperature for 3 minutes, and then heat it up to 230°C at a rate of 10°C / min. Record the heat flow curve of the heating and cooling process as a function of temperature, and then obtain the crystallization temperature from the curve.

[0090] Table 1

[0091]

[0092] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for preparing intercalated hydrotalcite, characterized in that, The preparation method includes: method one or method two; Method 1 involves mixing mixed solution A and mixed solution B, and then reacting them in the presence of a protective gas to obtain the intercalated hydrotalcite. Method two involves contacting and reacting mixed solution A and mixed solution B in the presence of a protective gas to obtain the intercalated hydrotalcite. In both methods one and two: the mixed solution A is a mixed solution of metal salt and modifier; the mixed solution B is a mixed solution of precipitant and functional object.

2. The preparation method according to claim 1, wherein, The metal salts include divalent metal salts and trivalent metal salts; The divalent metal ion of the divalent metal salt is Mg. 2+ Zn 2+ Co 2+ Ni 2+ Ca 2+ Fe 2+ and Cu 2+ At least one of them; The trivalent metal ion of the trivalent metal salt is Al. 3+ Co 3+ Ti 3+ Fe 3+ and Cr 3+ At least one of them; The divalent metal ion M of the metal salt 2+ With trivalent metal ions M 3+ The molar ratio is (2-4):1; Preferably, the metal salt is an inorganic metal salt.

3. The preparation method according to claim 1, wherein, The precipitant is at least one of NaOH, KOH, ammonia, urea, and hexamethylenetetramine.

4. The preparation method according to claim 1, wherein, The modifier is at least one of sodium dodecyl sulfate (SDS), sodium dodecyl sulfonate, sodium oleate, sodium stearate, and disodium ethylenediaminetetraacetate.

5. The preparation method according to claim 1, wherein, The functional object is an antioxidant; the antioxidant is preferably a hindered phenolic compound, and more preferably at least one of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, sodium β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, sodium β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid, sodium β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate, 3,5-di-tert-butyl-4-hydroxybenzoic acid, and sodium 3,5-di-tert-butyl-4-hydroxybenzoate.

6. The preparation method according to claim 1, wherein, The molar ratio of the modifier to the metal salt is 1:(10-200); The molar ratio of the metal salt to the precipitant is 1:(1.5-3); The molar ratio of the functional object to the precipitant is 1:(1-4); In the mixed solution A, the divalent metal ions M of the metal salt 2+ The molar concentration is 0.01–1 mol / L; In the mixed solution B, the molar concentration of the functional guest is 0.01 to 1 mol / L.

7. The preparation method according to claim 1, wherein, In both methods one and two: the reaction temperature is 25–180°C, and the reaction time is 1–12 hours; In Method 2, the pH value of the reaction system is controlled to be 9.5–10.

5.

8. Intercalated hydrotalcite prepared by the preparation method according to any one of claims 1-7.

9. The use of the intercalated hydrotalcite of claim 8 as an additive to reduce the crystallization temperature of polymers.

10. The application according to claim 9, wherein, The polymer is polypropylene resin.

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