Naphthalene carboxylic acid and / or derivative anion intercalated hydrotalcite and method for producing the same

Abstract

The application provides a naphthalene carboxylic acid and / or derivative acid intercalated layered double hydroxide and a preparation method thereof. The preparation method comprises: reacting a mixed system containing naphthalene carboxylic acid and / or derivative, or alkali metal salt of naphthalene carboxylic acid and / or derivative, divalent metal chloride, trivalent metal chloride and alkali to obtain the naphthalene carboxylic acid and / or derivative acid intercalated layered double hydroxide. The preparation method of the application uses magnesium chloride and aluminum chloride as metal ion sources, naphthalene carboxylic acid and / or derivative or salt thereof as anion source, and sodium hydroxide or potassium hydroxide as alkali source to prepare the LDHs, solves the problems of low flame retardant efficiency, poor ultraviolet resistance of common layered double hydroxide fillers and the problem that common layered double hydroxide fillers cannot have both flame retardant and ultraviolet resistance, and can simultaneously improve the flame retardant property and ultraviolet absorption property of the layered double hydroxide.

Description

Naphthalenecarboxylic acid and / or its derivatives anion intercalation hydrotalcites and their preparation methods Technical Field

[0001] This invention relates to a naphtholic acid carboxylic acid and / or its derivative anion intercalation type hydrotalcite and its preparation method, belonging to the field of hydrotalcite preparation technology. Background Technology

[0002] Layered double hydroxides (LDHs) are typical anionic intercalated layered compounds, a collective term for hydrotalcite (HT) and hydrotalcite-like compounds (HTLCs). Their layers consist of binary or multi-metal hydroxides, with corresponding anions filling the interlayer spaces to balance the charge within the layers. The general structural formula of common LDHs is... A typical example is natural hydrotalcite (Mg6Al2(OH)). 16 ·4H2O), other divalent (such as Mn) 2+ Ni 2+ Zn 2+ (etc.) and trivalent (e.g., Fe) 3+ Co 3 + Cr 3+ Metal ions (such as...) can also form similar layered compounds, which can be collectively referred to as hydrotalcite-like compounds. Their interlayer anions can be assembled into the interlayer of metal hydroxides through ion exchange, direct precipitation, and memory effect methods.

[0003] LDHs can be considered supramolecular structures with host-guest interactions. Within the host laminations of LDHs, metal ions and hydroxide ions interact through strong chemical bonds, while anions between the host and guest laminations primarily interact through Coulomb electrostatics, hydrogen bonds, or van der Waals forces, forming an ordered supramolecular composite material. In these materials, the host-guest interactions and the nanoscale properties exhibited by the two-dimensional layered structure endow them with unique physicochemical properties, including optical, electrical, magnetic, catalytic, and adsorption properties. Therefore, LDHs are widely used in catalysis and adsorption, optics, electrochemistry, magnetism, and corrosion protection.

[0004] LDHs also have wide applications in UV protection. The UV protection performance of LDHs is mainly reflected in two aspects: the blocking of ultraviolet rays by hydroxides and the absorption of ultraviolet rays by anions between the layers. The UV blocking properties of inorganic acid anion-intercalated hydrotalcite-like LDHs are affected by their morphology and particle size.

[0005] Because of the controllability of the types and ratios of cations in the LDH layers, and the exchangeability and intercalation of anions between layers, LDHs offer significant tunability in their properties. Materials can be designed by selecting the cations and anions involved in LDHs to meet different needs, and functionalization or modification of the materials' inherent functions can be achieved by controlling the ions in the LDH layers to meet diverse performance requirements. Therefore, LDHs possess enormous development and application potential.

[0006] The main synthetic methods for LDHs include coprecipitation, hydrothermal synthesis, ion exchange, calcination reduction, and other derivative methods.

[0007] Coprecipitation is a method for preparing LDHs by utilizing a precipitation reaction between a soluble metal salt, a soluble base, and a salt or acid of an intercalated anion. Coprecipitation is one of the most commonly used methods for LDH preparation due to its simplicity and mild reaction conditions. Because nitrate ions are among the most easily replaced by other anions, nitrates are mostly used in the coprecipitation method to successfully synthesize LDHs with specific anion intercalation, while chloride and sulfates are used relatively less. However, the oxidizing properties, toxicity, and price of nitrates are unfavorable for large-scale LDH production. my country has abundant magnesium chloride resources, and using magnesium chloride as a raw material for LDH synthesis via coprecipitation offers a significant cost advantage.

[0008] The hydrothermal method, a type of solvothermal method, uses water as a solvent or dispersant. The reactant mixture is placed in a sealed pressure vessel, and the powder is dissolved and recrystallized under pressure conditions using the saturated vapor pressure of water at a specific temperature. It has advantages such as high product crystal integrity, uniform particle size distribution, high product purity, and low particle agglomeration. The disadvantages of the hydrothermal method include high requirements for reaction equipment and high reaction temperatures, leading to higher energy consumption and increased production costs. It is also unfavorable for the synthesis of some less stable organic acid anion-intercalated LDHs.

[0009] Ion exchange is a method for preparing LDHs by synthesizing nitrate-intercalated LDHs via coprecipitation, drying the precipitate, and then adding it to a solution of the anion salt to be intercalated for ion exchange. Because nitrate is easily replaced in nitrate-intercalated LDHs, ion exchange is a relatively easy method for synthesizing specific ion-intercalated LDHs and is one of the most frequently used methods in scientific research. Another advantage of ion exchange is that it can preserve the original morphology and particle size distribution of nitrate-intercalated LDHs to a maximum extent, meaning the morphology of the intercalated LDHs can be indirectly controlled by controlling the morphology and particle size of the nitrate-intercalated LDHs. The disadvantages of ion exchange are its complex operation and incomplete interlayer ion replacement. There are also reports of using chloride or carbonate-intercalated LDHs instead of nitrate-intercalated LDHs for ion exchange preparation. However, this generally requires a higher concentration of the anion salt solution, a longer reaction time, and a higher reaction temperature, and the actual exchange efficiency is not as good as that of nitrate-intercalated LDHs. Another drawback of the ion exchange method is that LDH precursors must be synthesized first, and the preparation process has poor continuity, making it inconvenient for large-scale production.

[0010] The calcination-reduction method primarily utilizes the structural memory effect of LDHs. First, heating releases the thermal decomposition products of water and interlayer ions. Then, the calcined oxide is placed in a solution containing a specific anion to re-establish the intercalation structure of the LDHs, ultimately obtaining LDHs with the corresponding anion intercalation. Because LDHs are reduced in a solution containing the corresponding anion, they are not affected by interference from other anions. Therefore, the synthesized LDHs have high purity of interlayer anions and are free of other impurity ions. The calcination-reduction method is suitable for the synthesis of large-guest anion intercalated LDHs. Its disadvantages include the potential presence of a certain amount of amorphous solids in the synthesized product, high energy consumption in actual production, poor reaction continuity, and high cost.

[0011] Due to the inherent stability of organic compounds in organic acid anion-intercalated LDHs and the requirements for production efficiency and energy consumption in actual large-scale production, coprecipitation is the most likely method for the large-scale synthesis and application of organic acid anion-intercalated LDHs.

[0012] When natural or synthetic hydrotalcite is directly added to polymer flame retardants, its properties are similar to those of magnesium hydroxide and aluminum hydroxide. The flame retardant mechanism primarily involves an endothermic decomposition reaction, releasing H2O and CO2 and generating an oxide layer to isolate the diffusion of combustible gases. Simultaneously, the generated oxides not only catalyze the carbonization of combustibles to a certain extent but also effectively suppress smoke by adsorbing smoke particles. However, to achieve a good flame retardant effect, a large amount must be added, at which point the mechanical properties decrease significantly.

[0013] Magnesium-aluminum LDHs and other flame retardants such as magnesium hydroxide, organophosphates, and borates have a synergistic flame-retardant effect, which can improve their flame-retardant performance to a certain extent and reduce the amount added. However, as the main inorganic powder flame-retardant filler, their mechanical properties are still relatively weak, and when compounded with large amounts of organophosphates, they can introduce a certain degree of toxicity to the flame retardant, while also increasing their cost to some extent.

[0014] Artificially synthesized LDHs with transition metal layer plates and their composites exhibit good flame retardant properties. For example, when Xin et al. added Ni-Fe as the layer plate metal ions to epoxy resin, 2 wt% reduced the peak value of the maximum heat release rate in the cone calorimeter from 1730 K to 1070 K. The raw material for its synthesis is nitrate, with urea as the alkali source and carbon source, and it is synthesized hydrothermally at 150 °C for 24 h. Therefore, its synthesis cost is relatively high, and the high temperature and high pressure conditions make it difficult to carry out large-scale continuous production. Intercalation modification of magnesium aluminum hydrotalcite with organic acid anions can also improve its flame retardant effect and reduce the amount added. For example, Ehsan Naderi Kalali et al. introduced a mixed intercalation of cyclodextrin, chalcone and dodecyl sulfonic acid ions in LDHs, which has a good flame retardant effect. Adding 7% wt% to epoxy resin can make the vertical burning UL94 V-0 rating, and the peak heat release rate in cone calorimetry is reduced from 938 in pure epoxy resin to 318 W m-2. However, its raw material is nitrate, and the preparation process of intercalated anions is more complicated, which greatly increases its production complexity and cost.

[0015] Organic polymer materials are widely used in production and daily life due to their excellent comprehensive properties. However, most organic polymers have disadvantages such as flammability and easy aging under sunlight. Therefore, flame retardant and UV-resistant treatments are necessary for organic polymers. Common hydrotalcite is mainly used as a heat stabilizer for PVC. However, as a flame retardant, because its flame retardant mechanism is the same as that of magnesium hydroxide and other flame retardants, it generally suffers from low flame retardant efficiency. That is, low addition amounts result in poor flame retardancy, while high addition amounts lead to poor compatibility and a significant decrease in the mechanical properties of the composite material. Furthermore, common hydrotalcite does not possess strong UV absorption capabilities. Moreover, when hydrotalcite is used as a polymer filler, the focus is usually on developing only one aspect of its properties, failing to simultaneously achieve both flame retardancy and UV resistance.

[0016] In summary, when using natural hydrotalcite for flame retardancy, a large addition amount leads to a significant decrease in mechanical properties. Without specialized addition equipment, it is impossible to achieve a large addition amount (large addition amounts can cause inorganic powder sedimentation or even surface precipitation within the polymer, severely impacting mechanical properties), thus failing to effectively achieve flame retardancy. The preparation process of hydrotalcite with special morphology generally requires high temperature and pressure, consuming significant energy. Although flame retardant performance is improved to some extent, the problem of not being able to add large quantities to achieve the desired improvement remains, and significant issues with mechanical properties persist. When using transition metals to prepare highly catalytically active LDHs, the preparation process is often complex and costly, hindering mass production. Existing organic acid anion-intercalated LDHs generally only improve the flame retardancy or UV absorption performance of the matrix organic polymer, failing to simultaneously improve the flame retardancy, UV resistance, and mechanical properties of the organic polymer. In addition, most LDH-based flame retardants are difficult to put into practical applications due to problems such as high raw material prices or complex production processes. The design of inorganic powder fillers only strives to enhance one aspect of performance, and cannot simultaneously achieve the comprehensive performance of flame retardancy, UV resistance and other properties of the matrix organic polymer, let alone maintain mechanical properties under large addition amounts. Summary of the Invention

[0017] The purpose of this invention is to provide a naphtholic acid carboxylic acid and / or its derivative anion intercalated hydrotalcite and its preparation method, so as to overcome the shortcomings of the prior art.

[0018] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0019] This invention provides a method for preparing naphtholic acid and / or its derivative anion-intercalated hydrotalcite, comprising:

[0020] A mixture of alkali metal salts, divalent metal chlorides, trivalent metal sources, and bases containing naphtholic carboxylic acid and / or its derivatives is reacted to yield naphtholic carboxylic acid and / or its derivatives' anion-intercalated hydrotalcites.

[0021] More specifically, after the reaction of the mixed system is completed, it is aged, washed, and dried to obtain naphthic acid carboxylic acid and / or its derivatives of intercalated hydrotalcite.

[0022] The present invention also provides naphtholic acid and / or its derivatives of anion-intercalated hydrotalcite obtained by the preparation method described above.

[0023] Compared with the prior art, the beneficial effects of the present invention are at least as follows:

[0024] 1) The naphtholic acid and / or its derivatives of the present invention are intercalated hydrotalcites that may simultaneously improve the flame retardancy, UV resistance and mechanical properties of organic polymers.

[0025] 2) The method for preparing naphtholic acid carboxylic acid and / or its derivatives of intercalated hydrotalcite provided by the present invention utilizes magnesium chloride and aluminum chloride, which are abundant and inexpensive resources in my country, as metal ion sources, naphtholic acid and / or its derivatives or their salts as anion sources, and sodium hydroxide or potassium hydroxide as alkali sources. It is inexpensive and easy to manufacture in large quantities. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 is the XRD pattern of the LDHs prepared in Example 1 of the present invention.

[0028] Figure 2 is the XRD pattern of the LDHs prepared in Example 2 of the present invention.

[0029] Figure 3 is the XRD pattern of the LDHs prepared in Example 3 of the present invention.

[0030] Figure 4 is the XRD pattern of the LDHs prepared in Example 4 of the present invention.

[0031] Figure 5 is the XRD pattern of the LDHs prepared in Example 5 of the present invention.

[0032] Figure 6 is the XRD pattern of the LDHs prepared in Example 6 of the present invention. Detailed Implementation

[0033] In view of the deficiencies of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The technical solution of this invention will be clearly and completely described below. It mainly consists of a naphthic acid carboxylic acid and / or its derivative acid anion intercalation type hydrotalcite and its preparation method.

[0034] This invention provides a method for preparing naphtholic acid and / or its derivative anion-intercalated hydrotalcite, comprising:

[0035] A mixture of alkali metal salts, divalent metal chlorides, trivalent metal chlorides, and bases containing naphtholic carboxylic acid and / or its derivatives is reacted to obtain naphtholic carboxylic acid and / or its derivatives anion-intercalated hydrotalcite.

[0036] In some specific embodiments, the naphtholic carboxylic acid includes any one or a combination of two of naphtholic acid compounds and naphthaleneacetic acid compounds. Preferably, the naphtholic acid compounds include 1-naphthoic acid, 2-methoxy-1-naphthoic acid, 2-methyl-1-naphthoic acid, 2-hydroxy-1-naphthoic acid, 2-ethoxy-1-naphthoic acid, 3-methoxy-1-naphthoic acid, 4-methyl-1-naphthoic acid, 4-amino-1-naphthoic acid, 4-ethyl-1-naphthoic acid, 4-propyl-1-naphthoic acid, 4-ethoxy-1-naphthoic acid, 4-nitro-1-naphthoic acid, and 6-hydroxy-1-naphthoic acid. -Naphthoic acid, 2-naphthoic acid, 1-amino-2-naphthoic acid, 1-hydroxy-2-naphthoic acid, 1,4-dihydroxy-2-naphthoic acid, 3-amino-2-naphthoic acid, 3-methoxy-2-naphthoic acid, 3,5-dihydroxy-2-naphthoic acid, 3-hydroxy-7-methoxy-2-naphthoic acid, 5,6,7,8-tetrahydroxy-2-naphthoic acid, 6-amino-2-naphthoic acid, 6-methoxy-2-naphthoic acid, 6-(dimethylamino)-2-naphthoic acid, 6-hydroxy-2-naphthoic acid, 2-hydroxy-3-naphthoic acid, preferably, the naphthaleneacetic acid compounds include naphthaleneacetic acid.

[0037] Naphthalenecarboxylic acid (NCA) and its derivatives are important intermediates in organic synthesis. The carbon atoms in the ionic plane of these molecules are conjugated, and through structural design and optimization, good ultraviolet or visible light absorption properties can be obtained. Under alkaline conditions, the carboxyl group can lose a proton to form a negative ion, which can then be inserted into hydrotalcite-like minerals to form anion-intercalated hydrotalcites of NCA and its derivatives. The aromatic conjugated structure of NCA and its derivatives also makes them prone to carbonization during thermal decomposition. This means that when they are inserted into hydrotalcite-like minerals to prepare LDHs flame retardants, they can also promote carbonization during the combustion of organic polymers, thereby improving the flame retardancy of the organic polymers. Simultaneously, as organic ions, NCA and its derivatives, when inserted into hydrotalcite-like minerals, can improve the oleophilicity of the hydrotalcite surface, thereby improving the compatibility of LDHs with organic polymers and maintaining the mechanical properties of the organic polymers after addition.

[0038] In addition, using intercalated hydrotalcites such as benzoic acid and its derivatives as UV absorbers can improve the UV protection properties of organic polymers or sunscreens.

[0039] Furthermore, the divalent metal element in the divalent metal chloride includes any one or a combination of two or more of magnesium, copper, calcium, zinc, and manganese.

[0040] Furthermore, the metal element in the trivalent metal source includes any one or a combination of two or more of aluminum salts, aluminum hydroxide, sodium aluminate, and sodium aluminate. Preferably, the aluminum salt includes aluminum chloride.

[0041] Furthermore, the alkali includes alkali metal hydroxides.

[0042] In some specific embodiments, the amount of alkali in the mixed system is 0.9 × (2(n) M +n A )+n O )~1.1×(2(n M +n A )+n O ), where n M n represents the amount of substance of a divalent metallic element. A n represents the amount of substance of a trivalent metallic element. O This refers to the amount of naphthalenecarboxylic acid and / or its derivatives.

[0043] In some specific embodiments, the molar ratio of divalent metal elements to trivalent metal elements in the mixed system is 1:1 to 4:1.

[0044] Furthermore, the molar ratio of the trivalent metal element to naphthalenecarboxylic acid and / or its derivatives or alkali metal salts of naphthalenecarboxylic acid and / or its derivatives in the mixed system is 1:1 to 1:6.

[0045] In some specific embodiments, due to different feeding methods, two feeding methods can be used to obtain a mixed system.

[0046] (1) Dissolve the divalent metal chloride and the trivalent metal source in water to obtain the first solution;

[0047] A second solution is obtained by dissolving naphthalenecarboxylic acid and / or its derivatives, or alkali metal salts of naphthalenecarboxylic acid and / or its derivatives, and a base in water;

[0048] The first and second solutions are mixed and reacted to obtain naphthic acid carboxylic acid and / or its derivatives, which are intercalated hydrotalcites.

[0049] Preferably, the concentration of trivalent metal ions in the first solution is 0-0.8 mol / L.

[0050] Preferably, the concentration of effective hydroxide ions in the second solution is 0.1-4.0 mol / L.

[0051] (2) Dissolve the divalent metal chloride and the alkali metal salt of naphtholic acid and / or its derivatives in water to obtain a third solution;

[0052] A fourth solution is obtained by dissolving a trivalent metal source and an alkali in water;

[0053] The third and fourth solutions are mixed and reacted to obtain naphthic acid carboxylic acid and / or its derivatives, which are intercalated hydrotalcites.

[0054] Preferably, the concentration of divalent metal ions in the third solution is 0-0.8 mol / L.

[0055] Preferably, the concentration of effective hydroxide ions in the fourth solution is 0.1-4.0 mol / L.

[0056] In some more specific embodiments, the second solution is added to the first solution at a constant rate or the fourth solution is added to the third solution at a constant rate.

[0057] Alternatively, the first solution may be added to the second solution at a constant rate, or the third solution may be added to the fourth solution at a constant rate.

[0058] Alternatively, the first and second solutions can be added to the reaction vessel simultaneously, or the third and fourth solutions can be added to the reaction vessel simultaneously.

[0059] In some specific embodiments, the preparation method of the naphtholic acid and / or its derivative anion intercalated hydrotalcite further includes:

[0060] After the reaction of the mixed system is completed, it is aged, washed, and dried to obtain naphthic acid carboxylic acid and / or its derivatives of anion-intercalated hydrotalcite.

[0061] Furthermore, the reaction temperature is 20-90℃, and the reaction time is 0.5-3h.

[0062] And / or, the aging temperature is 20-200℃, and the aging time is 3-72h.

[0063] And / or, the drying temperature is 20-200°C.

[0064] In some more specific embodiments, the method for preparing the naphtholic carboxylic acid and / or its derivative anion-intercalated hydrotalcite includes:

[0065] (1) Solution preparation

[0066] Option 1: Naphthalenecarboxylic acid and / or its derivatives as organic ion sources

[0067] Weigh out specific amounts of divalent and trivalent metal chlorides, nM and nA respectively, ensuring that the ratio of the total amount of divalent metal elements to the total amount of trivalent metal elements is a specified value (nM). M ∶n A =1.0~4.0), add water to prepare a mixed solution A with a trivalent metal ion concentration of a certain concentration (0~0.8mol / L). Weigh out naphtholic carboxylic acid and / or its derivative n according to a certain multiple (1~6) of the molar amount of the trivalent metal element. O Weigh out a certain amount of alkali, making its amount of substance (2(n)). M +n A )+n O)*(1±0.1), and prepared into solution B with water, wherein the concentration of effective hydroxide ions in solution B is (0.1~4.0mol / L).

[0068] Option 2: Alkali metal salts of naphthalenecarboxylic acid and / or its derivatives as organic ion sources

[0069] At this point, due to the different methods of adding the materials, solutions A and B can be prepared using either method (a) or (b).

[0070] (a) Weigh out a certain amount of substance, n M and n A The divalent and trivalent metal chlorides ensure that the mole ratio of divalent metal elements to total trivalent metal elements is a specified value (n). M ∶n A =1.0~4.0), add water to prepare a mixed solution A with a trivalent metal ion concentration of a certain concentration (0~0.8mol / L). Weigh out alkali metal salts n of naphthic acid and / or its derivatives according to a certain multiple (1~6) of the molar amount of the trivalent metal element. OA Weigh out a certain amount of alkali, making its amount of substance 2(n). M +n A )*(1±0.1), and prepared into solution B with water, wherein the concentration of effective hydroxide ions in solution B is (0.1~4.0mol / L).

[0071] (b) Weigh out a certain amount of substance, n M For divalent metal chlorides, weigh out alkali metal salts of naphthic acid and / or its derivatives in multiples (1-6) of the molar amount of the trivalent metal element. OA A mixed solution A with a concentration of divalent metal ions of a certain degree (0–0.8 mol / L) is prepared by adding water. A certain amount of substance, n, is weighed out. A The trivalent metal chloride ensures that the molar ratio of divalent to trivalent metal elements is a specified value (n). M ∶n A =1.0~4.0), weigh a certain amount of alkali, so that its amount of substance is 2 (n M +n A )*(1±0.1), and prepare solution B with water, wherein the effective hydroxide ion concentration in solution B is (0.1~4.0mol / L). When synthesizing hydrotalcite using scheme two, aluminum hydroxide and sodium aluminate can be used as aluminum sources. In this case, the amount of alkali can be appropriately reduced according to the type and amount of aluminum source added.

[0072] (2) Reaction, aging, filtration and drying

[0073] The entire reaction can be carried out under nitrogen protection or without protection (without nitrogen protection, some of it will be converted into LDHs intercalated with carbonate ions) by stirring or sonication. The reaction can be added in any of the following three ways: (a) Place A in the reaction vessel, control the reaction temperature to the specified temperature (20-90℃), and then add B to the A solution at a certain rate; (b) Place B in the reaction vessel, control the reaction temperature to the specified temperature (20-90℃), and then add A to the B solution at a certain rate; (c) Preheat the reaction vessel and keep it at the specified temperature (20-90℃), and then add the A and B solutions to the reaction vessel simultaneously and uniformly at a proportional rate, ensuring that the addition starts and ends at the same time. After adding the feed, continue stirring and maintaining the temperature in the reactor for a certain period of time (0.5–3 h), then transfer to an aging container (if the aging temperature is higher than the boiling point of water, a pressure-resistant and heat-resistant container must be used). Aging is carried out at a certain temperature (20–200 degrees Celsius) for a certain period of time (3–72 h). The mixture is then filtered, washed with water until the filtrate is neutral, and then washed with an excess of a certain amount of water (0.1–2 times the volume of the reaction liquid) to further remove soluble impurities. The filter cake is dried to constant weight under vacuum or nitrogen atmosphere at a certain temperature (room temperature–200°C). Air drying can also be used, but its disadvantage is that a small portion of LDHs may be converted into carbonate-intercalated hydrotalcite or undergo partial oxidation of naphtholic acid and its derivatives at higher temperatures.

[0074] This invention also provides naphtholic acid and / or its derivatives of anion-intercalated hydrotalcite prepared by the aforementioned method.

[0075] The mechanism of this invention lies in the fact that carbon atoms in the ionic plane of naphthalenecarboxylic acid and its derivatives are mutually conjugated. Through structural design and optimization, better ultraviolet or visible light absorption performance can be obtained. Under alkaline conditions, the carboxyl group can lose a proton to form a negative ion, which can then be inserted into a hydrotalcite-like structure to form a hydrotalcite-like structure with anion intercalation of naphthalenecarboxylic acid and its derivatives. The aromatic conjugated structure of naphthalenecarboxylic acid and its derivatives also makes them prone to carbonization during thermal decomposition. This means that when they are inserted into hydrotalcite-like structures to prepare LDHs flame retardants, they can also promote carbonization during the combustion of organic polymers, thereby improving the flame retardancy of organic polymers. At the same time, after naphthalenecarboxylic acid and its derivatives are inserted into hydrotalcite-like structures as organic ions, they can improve the oleophilicity of the hydrotalcite surface, thereby improving the compatibility between LDHs and organic polymers and maintaining the mechanical properties of the organic polymers after addition.

[0076] In summary, this invention provides a hydrotalcite-like material and its synthesis method. This material is a hydrotalcite-like material with anion intercalation of naphthalic acid or substituted naphthalic acid. Magnesium chloride and aluminum chloride are used as metal ion sources, naphthoic acid and its derivatives or their salts are used as anion sources, and sodium hydroxide or potassium hydroxide is used as an alkali source to prepare a class of LDHs that may simultaneously improve the flame retardancy, UV resistance and mechanical retention of organic polymers.

[0077] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. It should be noted that the following embodiments are intended to facilitate the understanding of the present invention, and do not constitute any limitation thereof. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the manufacturer.

[0078] Example 1

[0079] Preparation of 1-naphthoic acid-intercalated LDHs using 1-naphthoic acid as raw material

[0080] Weigh 2.03 g of magnesium chloride hexahydrate and 1.21 g of aluminum chloride hexahydrate, add 50 mL of boiled distilled water to remove carbon dioxide, and prepare solution A. Transfer this solution to a 500 mL round-bottom three-necked flask, and purge with nitrogen for protection. Place the flask in a 60 °C water bath for 30 min. Separately weigh 2.58 g of 1-naphthoic acid and 1.85 g of sodium hydroxide, add 30 mL of distilled water to prepare solution B. Slowly add solution B to solution A at a rate of 2 mL / min, while purging with nitrogen for protection. After the addition is complete, continue stirring for 1 h. The reaction is carried out in a 60 °C water bath. After the reaction, transfer the solution to an Erlenmeyer flask, place it in a 60 °C oven to age for 24 hours, and then filter. The aged suspension was washed and filtered repeatedly with secondary water until the pH of the filtrate at the funnel outlet was 7. Then, 150 mL of secondary water was added in several batches for further washing. The filter cake was dried thoroughly in a vacuum drying oven at 60°C. After grinding, it was sieved through a 200-mesh sieve. Thus, 1-naphthoate intercalated LDHs with a magnesium-aluminum ratio of 2:1 were obtained.

[0081] Example 2

[0082] Preparation of 2-naphthoic acid-intercalated LDHs using 2-naphthoic acid as raw material

[0083] Weigh 2.03 g of magnesium chloride hexahydrate and 1.21 g of aluminum chloride hexahydrate, add 50 mL of boiled distilled water to remove carbon dioxide, and prepare solution A. Transfer this solution to a 500 mL round-bottom three-necked flask, and purge with nitrogen for protection. Place the flask in a 60 °C water bath for 30 min. Separately weigh 2.58 g of 2-naphthoic acid and 1.85 g of sodium hydroxide, add 30 mL of distilled water to prepare solution B. Slowly add solution B to solution A at a rate of 2 mL / min, while purging with nitrogen for protection. After the addition is complete, continue stirring for 1 h. The reaction is carried out in a 60 °C water bath. After the reaction, transfer the solution to an Erlenmeyer flask, place it in a 60 °C oven to age for 24 hours, and then filter. The aged suspension was washed and filtered repeatedly with secondary water until the pH of the filtrate at the funnel outlet was 7. Then, 150 mL of secondary water was added in several batches for further washing. The filter cake was dried thoroughly in a vacuum drying oven at 60°C. After grinding, it was sieved through a 200-mesh sieve. Thus, 2-naphthoate-intercalated LDHs with a magnesium-aluminum ratio of 2:1 were obtained.

[0084] Example 3

[0085] Preparation of 3-hydroxy-2-naphthoic acid-intercalated LDHs using 3-hydroxy-2-naphthoic acid as raw material

[0086] Weigh 2.03 g of magnesium chloride hexahydrate and 1.21 g of aluminum chloride hexahydrate, add 50 mL of boiled distilled water to remove carbon dioxide, and prepare solution A. Transfer this solution to a 500 mL round-bottom three-necked flask, and purge with nitrogen for protection. Place the flask in a 60 °C water bath for 30 min. Separately weigh 3.76 g of 3-hydroxy-2-naphthoic acid and 2.05 g of sodium hydroxide, add 30 mL of distilled water, and prepare solution B. Slowly add solution B to solution A at a rate of 2 mL / min, while purging with nitrogen for protection. After the addition is complete, continue stirring for 1 h. The reaction is carried out in a 60 °C water bath. After the reaction, transfer the solution to an Erlenmeyer flask, place it in a 60 °C oven to age for 24 hours, and then filter. The aged suspension was washed and filtered repeatedly with secondary water until the pH of the filtrate at the funnel outlet was 7. Then, 150 mL of secondary water was added in several batches for further washing. The filter cake was dried thoroughly in a vacuum drying oven at 60°C. After grinding, it was sieved through a 200-mesh sieve. Thus, 3-hydroxy-2-naphthoic acid intercalated LDHs with a magnesium-aluminum ratio of 2:1 were obtained.

[0087] Example 4

[0088] Preparation of 3-hydroxy-2-naphthoate intercalated LDHs using sodium 3-hydroxy-2-naphthoate as raw material

[0089] Weigh 3.82 g of 3-hydroxy-2-naphthoic acid and 0.90 g of sodium hydroxide, and add them to 50 mL of distilled water (boiled to remove carbon dioxide) to prepare solution A (equivalent to sodium 3-hydroxy-2-naphthoic acid). Weigh 2.03 g of magnesium chloride hexahydrate and add it to solution A. Transfer the solution to a 500 mL round-bottom three-necked flask and purge with nitrogen for protection. Place the flask in a 60 °C water bath for 30 min. Separately weigh 1.20 g of sodium hydroxide and 1.21 g of aluminum chloride hexahydrate, and add them to 30 mL of deionized water to prepare solution B. Slowly add solution B to solution A at a rate of 1 mL / min, while purging with nitrogen for protection. After the addition is complete, continue stirring for 1 h. The reaction is carried out in a 60 °C water bath. After the reaction, transfer the solution to an Erlenmeyer flask and age in a 60 °C oven for 24 hours. Filter the solution after aging. The aged suspension was washed and filtered repeatedly with secondary water until the pH of the filtrate at the funnel outlet was 7. Then, 150 mL of secondary water was added in several batches for further washing. The filter cake was dried thoroughly in a vacuum drying oven at 60°C. After grinding, it was sieved through a 200-mesh sieve. Thus, 3-hydroxy-2-naphthoic acid intercalated LDHs with a magnesium-aluminum ratio of 2:1 were obtained.

[0090] Example 5

[0091] Preparation of 1-naphthaleneacetic acid (NAA) root intercalated LDHs using 1-naphthaleneacetic acid as raw material

[0092] Weigh 2.03 g of magnesium chloride hexahydrate and 1.21 g of aluminum chloride hexahydrate, add 50 mL of boiled distilled water to remove carbon dioxide, and prepare solution A. Transfer this solution to a 500 mL round-bottom three-necked flask, and purge with nitrogen for protection. Place the flask in a 60 °C water bath for 30 min. Separately weigh 2.80 g of 1-naphthaleneacetic acid and 1.83 g of sodium hydroxide, add 30 mL of distilled water to prepare solution B. Slowly add solution B to solution A at a rate of 2 mL / min, while purging with nitrogen for protection. After the addition is complete, continue stirring for 1 h. The reaction is carried out in a 60 °C water bath. After the reaction, transfer the solution to an Erlenmeyer flask, place it in a 60 °C oven to age for 24 hours, and then filter. The aged suspension was washed and filtered repeatedly with secondary water until the pH of the filtrate at the funnel outlet was 7. Then, 150 mL of secondary water was added in several batches for further washing. The filter cake was dried thoroughly in a vacuum drying oven at 60°C. After grinding, it was sieved through a 200-mesh sieve. Thus, 1-naphthaleneacetic acid-intercalated LDHs with a magnesium-aluminum ratio of 2:1 were obtained.

[0093] Example 6

[0094] Preparation of 1-naphthaleneacetic acid (NAA) intercalated LDHs using potassium 1-naphthaleneacetate as raw material

[0095] Weigh 2.03 g of magnesium chloride hexahydrate and 1.21 g of aluminum chloride hexahydrate, add 50 mL of boiled distilled water to remove carbon dioxide, and prepare solution A. Transfer this solution to a 500 mL round-bottom three-necked flask, and purge with nitrogen for protection. Place the flask in a 60 °C water bath for 30 min. Separately weigh 3.36 g of potassium 1-naphthaleneacetate and 1.25 g of sodium hydroxide, add 30 mL of distilled water to prepare solution B. Slowly add solution B to solution A at a rate of 2 mL / min, while purging with nitrogen for protection. After the addition is complete, continue stirring for 1 h. The reaction is carried out in a 60 °C water bath. After the reaction, transfer the solution to an Erlenmeyer flask, place it in a 60 °C oven to age for 24 hours, and then filter. The aged suspension was washed and filtered repeatedly with secondary water until the pH of the filtrate at the funnel outlet was 7. Then, 150 mL of secondary water was added in several batches for further washing. The filter cake was dried thoroughly in a vacuum drying oven at 60°C. After grinding, it was sieved through a 200-mesh sieve. Thus, 1-naphthaleneacetic acid-intercalated LDHs with a magnesium-aluminum ratio of 2:1 were obtained.

[0096] Example 7

[0097] Preparation of 1-naphthoic acid-intercalated LDHs using 1-naphthoic acid as raw material

[0098] Weigh 2.03 g of magnesium chloride hexahydrate and 1.21 g of aluminum chloride hexahydrate, add 50 mL of boiled distilled water to remove carbon dioxide, and prepare solution A. Transfer this solution to a 500 mL round-bottom three-necked flask, and purge with nitrogen for protection. Place the flask in a 60 °C water bath for 30 min. Separately weigh 2.58 g of 1-naphthoic acid and 1.85 g of sodium hydroxide, add 30 mL of distilled water to prepare solution B. Slowly add solution B to solution A at a rate of 2 mL / min, while purging with nitrogen for protection. After the addition is complete, continue stirring for 3 h. The reaction is carried out in a 20 °C water bath. After the reaction, transfer the solution to an Erlenmeyer flask, place it in a 200 °C oven for aging for 3 hours, and then filter. The aged suspension was washed and filtered repeatedly with secondary water until the pH of the filtrate at the funnel outlet was 7. Then, 150 mL of secondary water was added in several batches for further washing. The filter cake was dried thoroughly in a vacuum drying oven at 200°C. After grinding, it was sieved through a 200-mesh sieve. Thus, 1-naphthoate intercalated LDHs with a magnesium-to-aluminum ratio of 2:1 were obtained.

[0099] Example 8

[0100] Preparation of 1-naphthoic acid-intercalated LDHs using 1-naphthoic acid as raw material

[0101] Weigh 2.03 g of magnesium chloride hexahydrate and 1.21 g of aluminum chloride hexahydrate, add 50 mL of boiled distilled water to remove carbon dioxide, and prepare solution A. Transfer this solution to a 500 mL round-bottom three-necked flask, and purge with nitrogen for protection. Place the flask in a 60 °C water bath for 30 min. Separately weigh 2.58 g of 1-naphthoic acid and 1.85 g of sodium hydroxide, add 30 mL of distilled water to prepare solution B. Slowly add solution B to solution A at a rate of 2 mL / min, while purging with nitrogen for protection. After the addition is complete, continue stirring for 0.5 h. The reaction is carried out in a 90 °C water bath. After the reaction, transfer the solution to an Erlenmeyer flask, place it in a 20 °C oven for aging for 72 hours, and then filter. The aged suspension was washed and filtered repeatedly with secondary water until the pH of the filtrate at the funnel outlet was 7. Then, 150 mL of secondary water was added in several batches for further washing. The filter cake was dried thoroughly in a vacuum drying oven at 20°C. After grinding, it was sieved through a 200-mesh sieve. Thus, 1-naphthoate-intercalated LDHs with a magnesium-aluminum ratio of 2:1 were obtained.

[0102] Comparative Example

[0103] To demonstrate that the naphthate carboxylate intercalated hydrotalcite synthesized in this invention can be used as an organic polymer flame retardant, this invention selected epoxy resin (E44) cured with diaminodiphenylmethane (DDM) as the organic polymer substrate for comparative studies. At the same time, aluminum hydroxide was selected as a general flame retardant for comparison.

[0104] The preparation process of epoxy resin and epoxy resin composites is as follows: Epoxy resin is preheated in a 90°C oil bath. If preparing composites, flame retardant is added to the preheated epoxy resin at a certain mass ratio and stirred evenly. Then, curing agent DDM is added to the preheated epoxy resin at a certain mass ratio at a certain rate, and defoaming is performed using a vacuum method. After pouring into a mold for curing, the limiting oxygen index of the corresponding materials is measured using a limiting oxygen index meter. In this comparative example, the corresponding species ratio in the epoxy resin composite is: epoxy resin: flame retardant: curing agent = 73.8 wt.%: 10 wt.%: 16.2 wt.%, while the epoxy resin: flame retardant: curing agent ratio is 82 wt.%: 18 wt.%. The limiting oxygen index test results are as follows.

[0105] The limiting oxygen index of the pure epoxy resin substrate is 25.1%.

[0106] The limiting oxygen index of the epoxy resin composite material with added aluminum hydroxide is 26.5%.

[0107] The limiting oxygen index of the epoxy resin composite material with added 1-naphthoic acid is 27.2%.

[0108] The limiting oxygen index of the epoxy resin composite material with added 2-naphthoic acid is 27.3%.

[0109] The limiting oxygen index of the epoxy resin composite material with added 3-hydroxy-2-naphthoic acid is 27.5%.

[0110] The limiting oxygen index of the epoxy resin composite material with added 1-naphthaleneacetic acid is 27.0%.

[0111] The flame retardant performance test results of the comparative proportion show that the naphthate carboxylate intercalated LDHs described in this invention have good limiting oxygen index test performance.

[0112] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0113] It should be understood that the technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made to the technical solutions of the present invention without departing from the spirit and scope of the claims are within the scope of protection of the present invention.

Claims

1. The use of a naphtholic acid carboxylic acid and / or its derivative anion-intercalated hydrotalcite in improving the properties of organic polymers, wherein the properties of the organic polymers include flame retardancy, UV resistance, and mechanical properties, and the preparation method of the naphtholic acid carboxylic acid and / or its derivative anion-intercalated hydrotalcite includes: A mixture comprising an acid or its alkali metal salt, a divalent metal chloride, a trivalent metal source, and a base is reacted to yield naphthalenecarboxylic acid and / or its derivatives, anion-intercalated hydrotalcites; wherein the acid is naphthalenecarboxylic acid and / or its derivatives; wherein the naphthalenecarboxylic acid is selected from 1-naphthoic acid, 2-methoxy-1-naphthoic acid, 2-methyl-1-naphthoic acid, 2-hydroxy-1-naphthoic acid, 2-ethoxy-1-naphthoic acid, and 3-methoxy-1-naphthoic acid. 4-Methyl-1-naphthoic acid, 4-amino-1-naphthoic acid, 4-ethyl-1-naphthoic acid, 4-propyl-1-naphthoic acid, 4-ethoxy-1-naphthoic acid, 4-nitro-1-naphthoic acid, 6-hydroxy-1-naphthoic acid, 1-amino-2-naphthoic acid, 1-hydroxy-2-naphthoic acid, 1,4-dihydroxy-2-naphthoic acid, 3-amino-2-naphthoic acid, 3-methoxy-2-naphthoic acid, 3,5-dihydroxy-2-naphthoic acid The mixture contains any one or a combination of two of the following: -naphthoic acid, 3-hydroxy-7-methoxy-2-naphthoic acid, 5,6,7,8-tetrahydroxy-2-naphthoic acid, 6-amino-2-naphthoic acid, 6-methoxy-2-naphthoic acid, 6-(dimethylamino)-2-naphthoic acid, 6-hydroxy-2-naphthoic acid, or 2-hydroxy-3-naphthoic acid; the divalent metal chloride contains a divalent metal element selected from any one or a combination of two or more of magnesium, copper, calcium, zinc, and manganese; the trivalent metal source contains a metal element selected from any one or a combination of two or more of aluminum salts, aluminum hydroxide, and sodium aluminate; the base is selected from alkali metal hydroxides; the molar ratio of the divalent metal element to the trivalent metal element in the mixed system is 1:1 to 4:1, and the molar ratio of the trivalent metal element to naphthalic acid carboxylic acid and / or its derivatives or alkali metal salts of naphthalic acid carboxylic acid and / or its derivatives is 1:1 to 1:

6.

2. The use according to claim 1, characterized in that: The aluminum salt includes aluminum chloride.

3. The use according to claim 1, characterized in that: The amount of alkali in the mixture is 0.9 × (2(n) M +n A )+n O ) ~ 1.1×(2(n M +n A )+n O ), where n M n represents the amount of substance of a divalent metallic element. A n represents the amount of substance of a trivalent metallic element. O This refers to the amount of naphthalenecarboxylic acid and / or its derivatives.

4. The use according to claim 1, characterized in that, The preparation method of the naphtholic acid and / or its derivative anion-intercalated hydrotalcite specifically includes: dissolving a divalent metal chloride and a trivalent metal source in water to obtain a first solution; dissolving naphtholic acid and / or its derivatives, or an alkali metal salt of naphtholic acid and / or its derivatives and a base in water to obtain a second solution; mixing the first solution and the second solution and reacting them to obtain naphtholic acid and / or its derivative anion-intercalated hydrotalcite.

5. The use according to claim 4, characterized in that: The concentration of trivalent metal ions in the first solution is 0.1-0.8 mol / L.

6. The use according to claim 4, characterized in that: The concentration of effective hydroxide ions in the second solution is 0.1-4.0 mol / L.

7. The use according to claim 1, characterized in that, The preparation method of the naphtholic acid and / or its derivative anion intercalated hydrotalcite specifically includes: dissolving a divalent metal chloride and an alkali metal salt of naphtholic acid and / or its derivative in water to obtain a third solution; dissolving a trivalent metal source and an alkali in water to obtain a fourth solution; mixing the third solution and the fourth solution and reacting them to obtain naphtholic acid and / or its derivative anion intercalated hydrotalcite.

8. The use according to claim 7, characterized in that: The concentration of divalent metal ions in the third solution is 0.2-0.8 mol / L.

9. The use according to claim 7, characterized in that: The concentration of effective hydroxide ions in the fourth solution is 0.1-4.0 mol / L.

10. The use according to any one of claims 4-6, characterized in that, The preparation method of the naphtholic acid and / or its derivative anion intercalated hydrotalcite specifically includes: adding the second solution to the first solution at a uniform rate; or, adding the first solution to the second solution at a uniform rate; or, adding the first solution and the second solution to a reaction vessel simultaneously.

11. The use according to any one of claims 7-9, characterized in that, The preparation method of the naphtholic acid and / or its derivative anion intercalated hydrotalcite specifically includes: adding the fourth solution to the third solution at a uniform rate; or, adding the third solution to the fourth solution at a uniform rate; or, adding the third solution and the fourth solution to the reaction vessel simultaneously.

12. The use according to claim 1, characterized in that, The preparation method of the naphtholic acid and / or its derivative anion intercalated hydrotalcite further includes: after the reaction of the mixed system is completed, aging, washing and drying are performed to obtain naphtholic acid and / or its derivative anion intercalated hydrotalcite.

13. The use according to claim 12, characterized in that: The reaction temperature is 20-90 °C, and the reaction time is 0.5-3 h.

14. The use according to claim 12, characterized in that: The aging temperature is 20-200℃, and the aging time is 3-72 h.

15. The use according to claim 12, characterized in that: The drying temperature is 20-200℃.

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