CN116041791B - Naphthalene anhydride microencapsulated magnesium hydroxide composite powder and preparation method and application thereof - Google Patents

Abstract

The invention provides a naphthalene anhydride microencapsulated magnesium hydroxide composite powder and a preparation method and application thereof, belonging to the technical field of functional materials. The compound powder of the microencapsulated magnesium hydroxide of the anhydride derivative of naphthalene of the invention is composed of anhydride derivative of naphthalene and magnesium hydroxide, wherein the anhydride derivative of naphthalene is the shell of the compound powder, the magnesium hydroxide is the inner core of the compound powder, and the mole ratio of the magnesium hydroxide to the anhydride derivative of naphthalene is 1:1 to 100. The preparation process is carried out under the protective atmosphere, and the naphthalene anhydride derivative, the magnesium hydroxide and the inorganic salt are sequentially mixed in a solvent for dehydration condensation reaction, thus obtaining the microencapsulated magnesium hydroxide composite powder of the naphthalene anhydride derivative. The naphthalene anhydride microcapsule magnesium hydroxide composite powder has the dual characteristics of light signal release and flame retardance, is used for preparing degradable substrate film materials, and can greatly improve the comprehensive performance of the composite material.

Description

A naphthalene anhydride microencapsulated magnesium hydroxide composite powder and its preparation method and application

Technical Field

The invention relates to the technical field of functional materials, and in particular to a naphthalene anhydride microencapsulated magnesium hydroxide composite powder and a preparation method and application thereof.

Background technique

Sustainable development is one of the main propositions of this era. Based on this, a variety of degradable materials have emerged. These degradable biomaterials generally have good biocompatibility and environmental friendliness, and are usually used in fiber preparation, adhesives, packaging materials, and biomedical equipment. At present, with the rapid consumption of traditional fossil energy and the inability to regenerate in the short term, degradable materials have penetrated into all aspects of daily life, including wearable devices, flexible solar cell substrates, mechano-optical materials, and barrier devices. Among them, mechano-stimuli-responsive materials are a type of functional material that has emerged in recent years. Under the condition of external force (stimulation), they can cause photophysical response due to changes in the micro-region environment, that is, there is a change in luminescence behavior. When the external stimulus disappears, it can even return to its initial state. This reversible behavior makes this type of material have the advantage of responding to external stimuli. It has great potential application value in the fields of sensor devices, anti-counterfeiting, data storage, drug delivery, cell imaging, etc., and has attracted widespread attention.

At present, the application of such materials is mainly concentrated in small organic molecules, metal-organic complexes, host-guest doped materials, and polymer substrates and even degradable substrates are rarely developed. Studies have shown that although the above materials are easy to synthesize, have diverse structures, and have relatively controllable performance, in most cases, they still need to rely on macromolecular materials, or polymer substrates as carriers, to make products. On the other hand, unfortunately, most degradable materials are basically easy to burn, have very poor flame retardant effects, and even produce molten droplets during combustion, which greatly promotes flame propagation and may cause casualties. Based on this, it is particularly urgent to develop efficient, sensitive, reliable and flame-retardant degradable mechano-responsive materials, which can greatly expand the application field of mechanical force-induced stimulus-responsive materials and fully obtain better safety guarantees.

As one of the core means to solve the above problems, high-performance functional powders have developed into the preferred solution for enhancing the functionality of various macromolecular materials in recent years. From the perspective of mechanoluminescence, the powder added to the polymer matrix should be able to release a strong light signal when the micro-region environment changes, that is, the apparent luminescence performance can be observed through the change of the microstructure, thereby achieving a visual response effect; from the perspective of ensuring safety and stability, flame retardant technology, as a passive protection technology, can cut off the circulation path between the three elements of combustion at a critical moment, making the polymer matrix a safe and controllable material. Halogen-free, smoke-suppressing, and clean powder materials have been widely used in this field. In summary, it is imperative to develop composite powders and preparation methods that have both functions.

Summary of the invention

The purpose of the present invention is to provide a naphthalene anhydride microencapsulated magnesium hydroxide composite powder and a preparation method and application thereof, so as to solve the technical problems in the prior art that mechanical force-induced stimulus response materials have poor responsiveness to external stimuli and poor flame retardancy.

In order to achieve the above-mentioned invention object, the present invention provides the following technical solutions:

The invention provides a naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder, which consists of a naphthalene anhydride derivative and magnesium hydroxide, wherein the naphthalene anhydride derivative is the outer shell of the composite powder, and the magnesium hydroxide is the inner core of the composite powder; the molar ratio of the magnesium hydroxide to the naphthalene anhydride derivative is 1:1-100.

Preferably, the particle size of the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder is 0.9-4.0 μm, wherein the particle size of the inner core is 0.8-3.0 μm.

Preferably, the structural formula of the naphthalene anhydride derivative is as shown in I:

Wherein, the Y comprises one of a benzene ring, a methylbenzene ring, a benzene ring methyl ether, a biphenyl ring, a terphenyl ring, a naphthalene ring, an anthracene ring, a phenylacetylene ring, a thiophene ring, a pyrazine ring, an indole ring, a quinoline ring, an isoquinoline ring, a pyridine ring, a furan ring, a pteridine ring, a quinoxaline ring, an acridine ring, a pyrimidine ring and a quinazoline ring.

The invention provides a method for preparing a naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder, comprising the following steps: in a protective atmosphere, a naphthalene anhydride derivative, magnesium hydroxide and an inorganic salt are sequentially mixed in a solvent for dehydration condensation reaction to obtain the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder.

Preferably, the protective atmosphere is one of a nitrogen atmosphere, a helium atmosphere and an argon atmosphere.

Preferably, the concentration ratio of the naphthalene anhydride derivative, magnesium hydroxide and inorganic salt is 1-100 mol/L: 1 mol/L: 10-100 mol/L; the inorganic salt comprises one or more of K ₂ CO ₃ , Cs ₂ CO ₃ and Ca(OH) ₂ .

Preferably, the solvent comprises one or more of ethanol, methanol, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile and ethyl acetate.

Preferably, the temperature of the dehydration condensation reaction is 30 to 80° C., and the time of the dehydration condensation reaction is 1 to 48 hours.

Preferably, the product of the dehydration condensation reaction is washed, centrifuged and freeze-dried in sequence; the freeze-drying temperature is -60 to -10°C, and the freeze-drying time is 1 to 72 hours.

The invention provides an application of a naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder in a degradable substrate. The degradable substrate and the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder are sequentially mixed in water and then dried to obtain a degradable substrate film material.

Preferably, the concentration ratio of the degradable substrate and the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder is 1 mol/L: 1-30 mol/L; the drying is carried out in two steps, the first step is drying at a temperature of 20-30°C and a drying time of 1-36 hours, and the second step is drying at a temperature of 40-80°C and a drying time of 1-36 hours.

Beneficial effects of the present invention:

(1) The naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder provided by the present invention is a naphthalene anhydride small molecule derivative and a clean, efficient, halogen-free inorganic base (MH) ingeniously combined to form organic-inorganic composite functional micro-nanoparticles. Among them, the naphthalene anhydride in the molecular structure can rotate freely in an environment of low micro-region stress, and the fluorescence signal becomes very weak because the mechanical rotation dissipates the excited state energy. When the micro-region stress gradually increases, the naphthalene anhydride rotation is gradually inhibited, and the fluorescence signal is released due to the return to the ground state through the channel of radiation transition, which can achieve an effective response to the micro-region stress change to a great extent, and realize visual detection of the potential risks induced by the local microenvironment stress change.

(2) The present invention combines organic naphthalene anhydride derivative functional molecules with ultrafine magnesium hydroxide powder (MH) through microencapsulation technology to prepare a naphthalene anhydride microencapsulated ultrafine MH composite powder, including functionalized naphthalene anhydride derivative wall material and ultrafine magnesium hydroxide core. The naphthalene anhydride derivative not only has the ability to respond to micro-area stress, but also has good carbonization due to its large conjugated aromatic hydrocarbon structure. The ultrafine MH itself has good smoke suppression and flame retardant properties. The combination of the two can be used to realize the visual detection of local micro-area stress changes and enhance the added value of traditional ultrafine MH, making a good demonstration for high-value powders. At the same time, the functionalized naphthalene anhydride derivative as a wall material can effectively enhance the compatibility of ultrafine MH in the matrix, and because of the presence of the core-shell structure, it can play different effects in different combustion stages, promoting the improvement of flame retardant performance.

(3) The preparation process of the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder of the present invention is simple and easy, the process is green and environmentally friendly, the yield is high, the raw material source is wide and low-cost, it is suitable for large-scale production and application, and has broad application prospects.

(4) The present invention mixes the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder with a part of the degradable substrate to prepare a degradable composite material. The addition of functionalized ultrafine MH will make the degradable substrate have multiple properties such as luminescence, flame retardancy, and reinforcement. That is, the performance of the degradable substrate can be improved in terms of function, safety, stability, and mechanical properties.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder obtained in Examples 1 to 5;

FIG2 is a schematic diagram of the mechanism of micro-region mechanical force induction of the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder obtained in Examples 1 to 5;

FIG3 is a fluorescence spectrum of the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder obtained in Example 1 in a solution environment with micro-region mechanical forces of different sizes;

FIG4 is a linear fitting diagram of the fluorescence intensity of the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder obtained in Example 1 and the logarithmic function of the mechanical force of micro-regions of different sizes;

FIG5 is an absorption spectrum of the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder prepared in Example 1 in different polar environments.

Detailed ways

The invention provides a naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder, which consists of a naphthalene anhydride derivative and magnesium hydroxide, wherein the naphthalene anhydride derivative is the outer shell of the composite powder, and the magnesium hydroxide is the inner core of the composite powder; the molar ratio of the magnesium hydroxide to the naphthalene anhydride derivative is 1:1-100, preferably 1:20-80.

In the present invention, the particle size of the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder is 0.9-4.0 μm, preferably 1.1-3.5 μm, and more preferably 1.2-3.0 μm; wherein the particle size of the inner core is 0.8-3.0 μm, preferably 1.0-2.8 μm, and more preferably 1.2-2.6 μm.

In the present invention, the ultrafine magnesium hydroxide powder prepared by mechanical method is preferably used, which generally needs to be ball-milled multiple times by a ball mill, and the magnesium hydroxide with a suitable particle size is selected by wind classification.

In the present invention, the structural formula of the naphthalene anhydride derivative is shown as Ⅰ:

Wherein, the Y comprises one of a benzene ring, a methylbenzene ring, a benzene ring methyl ether, a biphenyl ring, a terphenyl ring, a naphthalene ring, an anthracene ring, a phenylethynyl ring, a thiophene ring, a pyrazine ring, an indole ring, a quinoline ring, an isoquinoline ring, a pyridine ring, a furan ring, a pteridine ring, a quinoxaline ring, an acridine ring, a pyrimidine ring and a quinazoline ring, preferably one of a benzene ring, a methylbenzene ring, a benzene ring methyl ether, a biphenyl ring, a terphenyl ring, a naphthalene ring, anthracene ring, a phenylethynyl ring, a thiophene ring, a pyrazine ring, an indole ring, a quinoline ring, an isoquinoline ring, a pyridine ring, a furan ring, a pteridine ring, a quinoxaline ring and an acridine ring, further preferably one of a benzene ring, a methylbenzene ring, a benzene ring methyl ether, a biphenyl ring, a terphenyl ring, a naphthalene ring, anthracene ring, a phenylethynyl ring, a thiophene ring, a pyrazine ring, an indole ring, a quinoline ring, an isoquinoline ring and a pyridine ring.

The invention provides a method for preparing a naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder, comprising the following steps: in a protective atmosphere, a naphthalene anhydride derivative, magnesium hydroxide and an inorganic salt are sequentially mixed in a solvent for dehydration condensation reaction to obtain the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder.

In the present invention, the protective atmosphere is one of a nitrogen atmosphere, a helium atmosphere and an argon atmosphere.

In the present invention, the concentration ratio of the naphthalene anhydride derivative, magnesium hydroxide and inorganic salt is 1-100 mol/L: 1 mol/L: 10-100 mol/L, preferably 20-80 mol/L: 1 mol/L: 15-80 mol/L, and more preferably 20-80 mol/L: 1 mol/L: 20-60 mol/L; the inorganic salt comprises one or more of K ₂ CO ₃ , Cs ₂ CO ₃ and Ca(OH) ₂ , preferably K ₂ CO ₃ and/or Cs ₂ CO ₃ , and more preferably K ₂ CO ₃ .

In the present invention, the solvent comprises one or more of ethanol, methanol, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile and ethyl acetate, preferably one or more of ethanol, methanol, tetrahydrofuran, N,N-dimethylformamide and dimethyl sulfoxide, and further preferably one or more of ethanol, methanol and N,N-dimethylformamide.

In the present invention, the temperature of the dehydration condensation reaction is 30 to 80° C., preferably 40 to 70° C., and more preferably 50 to 60° C.; the time of the dehydration condensation reaction is 1 to 48 hours, preferably 5 to 44 hours, and more preferably 10 to 40 hours.

In the present invention, the product of the dehydration condensation reaction is washed, centrifuged and freeze-dried in sequence; the freeze-drying temperature is -60 to -10°C, preferably -50 to -20°C, and more preferably -40 to -30°C; the freeze-drying time is 1 to 72 hours, preferably 12 to 60 hours, and more preferably 24 to 48 hours.

In the present invention, the centrifugal speed during centrifugation is preferably 900 to 9000 rpm, more preferably 1500 to 8000 rpm; the centrifugal time is preferably 5 to 60 min, more preferably 15 to 45 min.

The freeze drying process of the present invention is to disperse the obtained dehydration condensation reaction product in a small amount of water and freeze it, and then use a freeze dryer to perform solid sublimation at low temperature to obtain the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder.

The invention provides an application of a naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder in a degradable substrate. The degradable substrate and the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder are sequentially mixed in water and then dried to obtain a degradable substrate film material.

In the present invention, the concentration ratio of the degradable substrate to the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder is 1 mol/L: 1-30 mol/L, preferably 1 mol/L: 5-25 mol/L, and more preferably 1 mol/L: 10-20 mol/L.

In the present invention, the degradable substrate comprises one of polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate-adipate (PBSA), polycaprolactone (PCL), polypropylene carbonate (PPC), polyglycolic acid (PGA), polyvinyl alcohol (PVA) and polyhydroxyalkanoate (PHA), preferably one of polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate-adipate (PBSA), polycaprolactone (PCL), polypropylene carbonate (PPC), polyglycolic acid (PGA) and polyvinyl alcohol (PVA), and further preferably one of polybutylene succinate (PBS), polycaprolactone (PCL), polypropylene carbonate (PPC), polyglycolic acid (PGA) and polyvinyl alcohol (PVA).

When the degradable substrate is mixed with water in the present invention, the stirring speed during the mixing is preferably 600 to 1600 rpm, more preferably 800 to 1400 rpm; the stirring time is preferably 1 to 24 hours, more preferably 5 to 20 hours; the temperature during the mixing is 60 to 90°C, preferably 65 to 85°C, more preferably 70 to 80°C.

When the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder is mixed with water in the present invention, the stirring speed during the mixing is preferably 400 to 1200 rpm, more preferably 600 to 1000 rpm; the stirring time is preferably 1 to 36 hours, more preferably 9 to 27 hours; the mixing temperature is preferably 50 to 90°C, more preferably 60 to 80°C.

In the present invention, the drying is carried out in two steps. The first step is carried out at a drying temperature of 20 to 30°C, preferably 22 to 28°C, and more preferably 25°C; the drying time is 1 to 36 hours, preferably 4 to 32 hours, and more preferably 8 to 24 hours; the second step is carried out at a drying temperature of 40 to 80°C, preferably 45 to 75°C, and more preferably 50 to 70°C; the drying time is 1 to 36 hours, preferably 4 to 32 hours, and more preferably 8 to 24 hours.

The thickness of the degradable substrate film material prepared in the present invention is preferably controlled within the range of 0.1 to 0.6 mm, and more preferably within the range of 0.3 to 0.4 mm.

The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

Example 1

40 mol of a naphthalene anhydride derivative, 1 mol (58.3 g) of magnesium hydroxide, and 20 mol of K ₂ CO ₃ are sequentially mixed with 1 L of ethanol, wherein the structural formula of the naphthalene anhydride derivative is shown below, and Y is a benzene ring. Then, a dehydration condensation reaction is carried out at 50° C. for 24 hours under a nitrogen atmosphere. During the reaction, the stirring speed is controlled at 600 rpm. After the reaction, the reaction product is washed with deionized water and then centrifuged. The centrifugal speed is 3000 rpm and the centrifugal time is 30 minutes. Finally, the centrifuged product is dispersed in a small amount of water and freeze-dried. The freeze-drying temperature is -30° C. and the freeze-drying time is 36 hours. Naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder can be obtained, wherein the D ₅₀ of the magnesium hydroxide core is 1.165 μm.

1 mol of PVA degradable substrate was dispersed in 1 L of water with a stirring speed of 1000 rpm, a stirring temperature of 80°C and a stirring time of 10 h. Then, 20 mol of naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder was added, and the stirring speed was controlled to 900 rpm, the stirring temperature was 80°C and the stirring time was 24 h. The mixed solution was poured into a glass dish and dried in steps. The first step was dried at a temperature of 25°C and a drying time of 18 h. The second step was dried at a temperature of 50°C and a drying time of 24 h to obtain a degradable substrate film material with a thickness of 0.3 mm.

Example 2

1 mol of a naphthalene anhydride derivative, 1 mol (58.3 g) of magnesium hydroxide, and 10 mol of K ₂ CO ₃ are sequentially mixed with 1 L of ethanol, wherein the structural formula of the naphthalene anhydride derivative is shown below, and Y is a benzene ring. Then, a dehydration condensation reaction is carried out at 30° C. for 48 hours under a nitrogen atmosphere. During the reaction, the stirring speed is controlled at 100 rpm. After the reaction, the reaction product is washed with deionized water and then centrifuged. The centrifugal speed is 900 rpm and the centrifugal time is 60 minutes. Finally, the centrifuged product is dispersed in a small amount of water and freeze-dried. The freeze-drying temperature is -10° C. and the freeze-drying time is 72 hours. Naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder can be obtained, wherein the D ₅₀ of the magnesium hydroxide core is 1.418 μm.

1 mol of PVA degradable substrate was dispersed in 1 L of water with a stirring speed of 600 rpm, a stirring temperature of 60°C and a stirring time of 24 h. Then, 1 mol of naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder was added with a stirring speed of 400 rpm, a stirring temperature of 50°C and a stirring time of 36 h. The mixed solution was poured into a glass dish and dried in steps. The first step was dried at a temperature of 25°C and a drying time of 36 h. The second step was dried at a temperature of 40°C and a drying time of 36 h to obtain a degradable substrate film material with a thickness of 0.3 mm.

Example 3

100 mol of a naphthalene anhydride derivative, 1 mol of magnesium hydroxide, and 100 mol of K ₂ CO ₃ are sequentially mixed with 1 L of ethanol, wherein the structural formula of the naphthalene anhydride derivative is shown below, and Y is a benzene ring. Then, a dehydration condensation reaction is carried out at 80° C. for 1 hour under a nitrogen atmosphere. During the reaction, the stirring speed is controlled at 600 rpm. After the reaction, the reaction product is washed with deionized water and then centrifuged. The centrifugal speed is 9000 rpm and the centrifugal time is 5 minutes. Finally, the centrifuged product is dispersed in a small amount of water and freeze-dried. The freeze-drying temperature is -60° C. and the freeze-drying time is 1 hour. Naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder can be obtained, wherein the D ₅₀ of the magnesium hydroxide core is 1.356 μm.

1 mol of PVA degradable substrate was dispersed in 1 L of water with a stirring speed of 1600 rpm, a stirring temperature of 90°C and a stirring time of 1 h. Then, 30 mol of naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder was added with a stirring speed of 1200 rpm, a stirring temperature of 90°C and a stirring time of 1 h. The mixed solution was poured into a glass dish and dried in steps. The first step was dried at a temperature of 25°C and a drying time of 1 h. The second step was dried at a temperature of 80°C and a drying time of 1 h to obtain a degradable substrate film material with a thickness of 0.3 mm.

Example 4

80 mol of a naphthalene anhydride derivative, 1 mol of magnesium hydroxide, and 50 mol of Cs ₂ CO ₃ are sequentially mixed with 1 L of ethanol, wherein the structural formula of the naphthalene anhydride derivative is shown below, and Y is a naphthalene ring. Then, a dehydration condensation reaction is carried out at 60° C. for 30 hours under a nitrogen atmosphere. During the reaction, the stirring speed is controlled at 1000 rpm. After the reaction, the reaction product is washed with deionized water and then centrifuged. The centrifugal speed is 8000 rpm and the centrifugal time is 10 minutes. Finally, the centrifuged product is dispersed in a small amount of water and freeze-dried. The freeze-drying temperature is -40° C. and the freeze-drying time is 10 hours. Naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder can be obtained, wherein the D ₅₀ of the magnesium hydroxide kernel is 1.389 μm.

1 mol of PLA degradable substrate was dispersed in 1 L of water, with a stirring speed of 1600 rpm, a stirring temperature of 90°C and a stirring time of 1 h, and then 10 mol of naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder was added, and the stirring speed was controlled to be 1200 rpm, the stirring temperature was 90°C and the stirring time was 1 h. The mixed solution was poured into a glass dish and dried in steps, the first step of drying was at a temperature of 25°C and a drying time of 1 h, and the second step of drying was at a temperature of 80°C and a drying time of 1 h, to obtain a degradable substrate film material with a thickness of 0.4 mm.

Example 5

50 mol of a naphthalene anhydride derivative, 1 mol of magnesium hydroxide, and 50 mol of Ca(OH) ₂ are sequentially mixed with 1 L of ethanol, wherein the structural formula of the naphthalene anhydride derivative is shown below, and Y is a pyridine ring. Then, a dehydration condensation reaction is carried out at 70° C. for 20 hours under a nitrogen atmosphere. During the reaction, the stirring speed is controlled at 1200 rpm. After the reaction, the reaction product is washed with deionized water and then centrifuged. The centrifugal rate is 6000 rpm and the centrifugal time is 20 minutes. Finally, the centrifuged product is dispersed in a small amount of water and freeze-dried. The freeze-drying temperature is -40° C. and the freeze-drying time is 20 hours. To obtain a naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder, wherein the D ₅₀ of the magnesium hydroxide kernel is 1.226 μm.

1 mol of PPC degradable substrate was dispersed in 1 L of water with a stirring speed of 1600 rpm, a stirring temperature of 90°C and a stirring time of 1 h. Then, 10 mol of naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder was added with a stirring speed of 1200 rpm, a stirring temperature of 90°C and a stirring time of 1 h. The mixed solution was poured into a glass dish and dried in steps. The first step was dried at a temperature of 25°C and a drying time of 20 h. The second step was dried at a temperature of 50°C and a drying time of 20 h to obtain a degradable substrate film material with a thickness of 0.4 mm.

Comparative Example 1

0.5 mol of a naphthalene anhydride derivative, 1 mol of magnesium hydroxide, and 40 mol of K ₂ CO ₃ are sequentially mixed with 1 L of ethanol, wherein the structural formula of the naphthalene anhydride derivative is shown below, and Y is a benzene ring. Then, a dehydration condensation reaction is carried out at 45° C. for 32 hours under a nitrogen atmosphere. After the reaction, the reaction product is washed with deionized water and then centrifuged at a centrifugal speed of 4500 rpm for 30 minutes. Finally, the centrifuged product is dispersed in a small amount of water for freeze drying at a freeze drying temperature of -30° C. for 36 hours. Thus, a naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder is obtained, wherein the D ₅₀ of the magnesium hydroxide core is 1.345 μm.

1 mol of PVA degradable substrate was dispersed in 1 L of water with a stirring speed of 1000 rpm, a stirring temperature of 80°C and a stirring time of 12 h. Then, 20 mol of naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder was added with a stirring speed of 800 rpm, a stirring temperature of 70°C and a stirring time of 18 h. The mixed solution was poured into a glass dish and dried in steps. The first step was dried at a temperature of 25°C and a drying time of 16 h. The second step was dried at a temperature of 60°C and a drying time of 18 h to obtain a degradable substrate film material with a thickness of 0.3 mm.

Comparative Example 2

120 mol of a naphthalene anhydride derivative, 1 mol of magnesium hydroxide, and 50 mol of K ₂ CO ₃ are sequentially mixed with 1 L of ethanol, wherein the structural formula of the naphthalene anhydride derivative is shown below, and Y is a benzene ring. Then, a dehydration condensation reaction is carried out at 45° C. for 40 hours under a nitrogen atmosphere. After the reaction, the reaction product is washed with deionized water and then centrifuged at a centrifugal speed of 5000 rpm for 30 minutes. Finally, the centrifuged product is dispersed in a small amount of water for freeze drying at a freeze drying temperature of -25° C. for 40 hours. Thus, a naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder can be obtained, wherein the D ₅₀ of the magnesium hydroxide core is 1.275 μm.

1 mol of PVA degradable substrate was dispersed in 1 L of water with a stirring speed of 1200 rpm, a stirring temperature of 70°C and a stirring time of 14 h. Then, 20 mol of naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder was added with a stirring speed of 1000 rpm, a stirring temperature of 50°C and a stirring time of 28 h. The mixed solution was poured into a glass dish and dried in steps. The first step was dried at a temperature of 25°C and a drying time of 20 h. The second step was dried at a temperature of 65°C and a drying time of 20 h to obtain a degradable substrate film material with a thickness of 0.3 mm.

Comparative Example 3

1 mol of PVA degradable substrate was dispersed in 1 L of water, with a stirring speed of 1200 rpm, a stirring temperature of 70°C and a stirring time of 14 h, and then 20 mol of mechanically ball-milled fine magnesium hydroxide powder was added, and the stirring speed was controlled to 1000 rpm, the stirring temperature was 50°C and the stirring time was 28 h. The mixed solution was poured into a glass dish and dried in steps, the first step of drying was at a temperature of 25°C and a drying time of 20 h, and the second step of drying was at a temperature of 65°C and a drying time of 20 h, to obtain a degradable substrate film material with a thickness of 0.3 mm.

Performance Testing:

The naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powders prepared in Examples 1 to 5 and Comparative Examples 1 to 2 and the commercially available fine MH powder were tested for particle size and oil absorption. The particle size test method: the particle size and distribution of the powder were measured by a laser particle distribution measuring instrument, and the oil absorption was tested according to the DB/T5211.15-2014 standard. The test results are shown in Table 1:

Table 1 Particle size and oil absorption test results

serial number D ₅₀ (μm) Oil absorption value (mL/100g) Example 1 1.295 27 Example 2 1.603 29 Example 3 1.506 29 Example 4 1.652 28 Example 5 1.478 26 Comparative Example 1 2.121 33 Comparative Example 2 1.931 31 Comparative Example 3 3.278 38

It can be seen from the test results in Table 1 that when the functionalized naphthalene anhydride derivative and ultrafine MH are added in a suitable molar ratio for compounding, the median particle size _D50 of the obtained naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder shows a significant downward trend, and the oil absorption value is also relatively low; in contrast, when the molar ratio of the added naphthalene anhydride derivative to MH is too low (lower than 1:1, such as Comparative Example 1), the surface of the MH powder cannot be well wrapped by the naphthalene anhydride derivative, and it is difficult to form a complete wall material, that is, a bare phenomenon occurs, and the surface modification effect of the MH powder is limited, which is manifested in a significant upward trend in both particle size and oil absorption value; however, when the molar ratio of the naphthalene anhydride derivative to MH is too high (greater than 100:1, such as Comparative Example 2), the naphthalene anhydride derivative may cause self-aggregation due to excessive addition, which will not only cause the composite powder to have an excessively large particle size, but also cause a variety of small molecule aggregates to fill it, and the resulting product is difficult to compound with MH to play a comprehensive role. Compared with the comparative example 3, the above-mentioned examples 1 to 5 and comparative examples 1 to 2 show that when the MH powder is not treated in any way, due to the presence of a large number of hydroxyl groups on its surface, it is very easy to agglomerate, and the result of the median particle size test is significantly increased, and the oil absorption value is significantly increased, which is not conducive to the improvement of the comprehensive performance of the composite powder. The above results show that the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder provided by the present invention can significantly improve the comprehensive performance of MH, especially the improvement of its surface performance is particularly obvious.

Spectroscopy test:

The composite powder used in the spectroscopy test is the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder prepared in Example 1.

(1) Luminescence performance test of fluorescent rotors in different solvents:

The composite powder was prepared into a 1 mM mother liquor, and its final concentration was controlled to be 10 μM during the specific test. Then, it was added into six common solvents, including toluene, tetrahydrofuran, ethanol, dimethyl sulfoxide, propylene glycol and water, respectively, and the absorption spectra of the composite powder in various conventional solvents were tested. The test results are shown in FIG3 and Table 2. The absorption spectrum peaks of the composite powder in various solvents are similar, showing a slight red-shift trend, indicating that the composite powder is suitable for a variety of solvents and has a relatively broad universal application potential.

Table 2 Absorption spectrum peak and absorbance data of composite powder of Example 1

(2) Response test of naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder to micro-area mechanical force induction:

The physical environment of the micro-region of the solvent was changed by preparing a mixed solution of glycerol/deionized water with different volume fractions, wherein the volume fractions of glycerol were 0%, 10%, 30%, 50%, 70%, 90%, and 99%, respectively. When tested at room temperature, 10 μM of naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder was added to the test solution, and the excitation wavelength was set to 430 nm. The specific test results are shown in Figure 4. As can be seen from Figure 4, as the physical viscosity of the micro-region in the solution increases, the mechanical rotation of the naphthalene anhydride derivative becomes increasingly difficult and is suppressed. The excited electrons return to the ground state by radiation transition, and the light signal released gradually increases. In particular, when the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder is added to 99% glycerol, the intensity of the light signal released reaches a maximum value. Compared with water with very low physical viscosity, the intensity of the released fluorescence signal has increased by about 14 times (the specific test results are shown in Table 3), and the detection effect is significant. Further, using -Hoffman equation is used to quantify the micro-area viscosity and the light signal intensity to determine the response effect of the composite powder to the micro-area stress change. The final fitting result is shown in Figure 5. It can be found that the composite powder only presents an approximately linear result in the environment of low micro-area viscosity, and presents another linearly related result in the environment of high micro-area viscosity. The slopes of the two are different, indicating that the composite powder has a more significant response effect to the low micro-area stress change, and also has a certain response effect to the high micro-area stress change, that is, it can be used to monitor the stress changes of various physical micro-areas.

Table 3 Optical signal intensity of composite powder added to glycerol/deionized water solution with different volume fractions

Volume fraction of glycerol The fluorescence intensity 0% 130.8 10% 401.9 30% 823.5 50% 1111.8 70% 1360.6 90% 1565.8 99% 1823.6

Degradable substrate film material performance test:

The PVA degradable substrate film materials prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were prepared into test specimens according to standard sizes, and performance tests were performed according to the following standards. The performance test results are shown in Table 4.

Vertical burning test: Tested in accordance with standard ASTM D4804-14;

Total heat release: the heat generated by heating from room temperature to 740°C using a microcalorimeter;

Oxygen index test: Tested in accordance with standard ASTM D2863-17.

Table 4 Performance test results of PVA degradable substrate film materials

Here, the combustion performance of the degradable substrate film material was tested by a vertical combustion instrument, a microcalorimeter and a limiting oxygen index. From the results presented in Table 4, it can be seen that when the molar ratio of the naphthalene anhydride derivative and the ultrafine MH is within a reasonable range, the composite powder prepared by adding it to the polymer matrix can exert a good synergistic flame retardant effect during the combustion process, which is specifically reflected in the ability to pass the vertical combustion VTM-0 level, the total heat release can be greatly reduced, and the limiting oxygen index can be maintained at a high level; in contrast, when the molar ratio of the naphthalene anhydride derivative and the ultrafine MH is too large or too small, or the naphthalene anhydride derivative is not added, the composite powder added to the polymer matrix can not be vertically burned. It is difficult to pass the burning grade, and the total heat release is high and the limiting oxygen index is low. The above reasons may be attributed to the fact that the naphthalene anhydride derivative itself is a large conjugated aromatic molecule, which is easy to form carbon in the combustion process and adhere to the carbon layer at the combustion front. At the same time, the internal ultrafine MH itself has good flame retardant properties. It can generate non-combustible MgO, an inorganic substance, which is deposited at the combustion front during the combustion process, and can release more water vapor to dilute the molecular fragments of combustion degradation, that is, it can block the fuel consumption cycle pathway in the gas phase and the solid phase at the same time. Combined with the large amount of carbonization of the outer naphthalene anhydride molecules, the two show good synergy, but the molar concentrations of the two must match and cannot be too large or too small.

The naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder provided by the present invention can have the dual characteristics of light signal release and flame retardancy. The excitation wavelength required for the light signal release is just around the emission wavelength of 365nm of a common portable ultraviolet lamp, which is suitable for exciting light signals through ultraviolet emission light, has the effects of portability and rapid detection in various occasions, and is very convenient; the interior is an ultrafine MH core, which can provide good smoke suppression and flame retardancy; the naphthalene anhydride derivative can also provide necessary surface modification performance to improve the dispersibility of ultrafine MH in the matrix, and has a great improvement effect on the comprehensive performance of the composite material; the obtained composite powder is prepared by a one-step method, has the characteristics of a green preparation process, a high yield, a wide range of low costs, and the like, and is in line with the current green and low-carbon development concept.

It can be seen from the above embodiments that the present invention provides a naphthalene anhydride microencapsulated magnesium hydroxide composite powder and its preparation method and application. The naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder of the present invention is composed of a naphthalene anhydride derivative and magnesium hydroxide, wherein the naphthalene anhydride derivative is the outer shell of the composite powder, and the magnesium hydroxide is the inner core of the composite powder, and the molar ratio of magnesium hydroxide to the naphthalene anhydride derivative is 1:1 to 100. The preparation process is carried out under a protective atmosphere, and the naphthalene anhydride derivative, magnesium hydroxide, and inorganic salt are sequentially mixed in a solvent for dehydration condensation reaction to obtain the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder. The naphthalene anhydride microencapsulated magnesium hydroxide composite powder of the present invention has the dual characteristics of light signal release and flame retardancy, and is used in the preparation of degradable substrate film materials, which can greatly improve the comprehensive performance of the composite material.

The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims (9)

1. The naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder is characterized by comprising naphthalene anhydride derivatives and magnesium hydroxide, wherein the naphthalene anhydride derivatives are shells of the composite powder, and the magnesium hydroxide is an inner core of the composite powder; the molar ratio of the magnesium hydroxide to the naphthalene anhydride derivative is 1:1 to 100;

the structural formula of the naphthalene anhydride derivative is shown as I:

Wherein Y comprises one of a benzene ring, a methyl benzene ring, a benzene ring methyl ether, a biphenyl ring, a terphenyl ring, a naphthalene ring, an anthracene ring, a thiophene ring, a pyrazine ring, an indole ring, a quinoline ring, an isoquinoline ring, a pyridine ring, a furan ring, a pteridine ring, a quinoxaline ring, an acridine ring, a pyrimidine ring, and a quinazoline ring.

2. The naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder according to claim 1, wherein the particle size of the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder is 0.9 to 4.0 μm, and wherein the particle size of the inner core is 0.8 to 3.0 μm.

3. The method for preparing the micro-encapsulated magnesium hydroxide composite powder of the naphthalene anhydride derivative as claimed in claim 1 or 2, comprising the steps of: under the protective atmosphere, the naphthalene anhydride derivative, magnesium hydroxide and inorganic salt are sequentially mixed in a solvent for dehydration condensation reaction, and the microencapsulated magnesium hydroxide composite powder of the naphthalene anhydride derivative can be obtained.

4. The method according to claim 3, wherein the concentration ratio of the naphthalene anhydride derivative, magnesium hydroxide and inorganic salt is 1 to 100mol/L:1mol/L:10 to 100mol/L; the inorganic salt comprises one or more of K ₂CO₃、Cs₂CO₃ and Ca (OH) ₂.

5. The method according to claim 4, wherein the solvent comprises one or more of ethanol, methanol, tetrahydrofuran, N-dimethylformamide, dimethyl sulfoxide, acetonitrile and ethyl acetate.

6. The method according to claim 4 or 5, wherein the dehydration condensation reaction is carried out at a temperature of 30 to 80℃for a time of 1 to 48 hours.

7. The method according to claim 3, wherein the product of the dehydration condensation reaction is washed, centrifuged and freeze-dried sequentially; the freeze drying temperature is-60 to-10 ℃, and the freeze drying time is 1 to 72 hours.

8. The application of the compound powder of the naphthalene anhydride derivative microencapsulated magnesium hydroxide in the degradable base material, which is characterized in that the degradable base material and the compound powder of the naphthalene anhydride derivative microencapsulated magnesium hydroxide are sequentially mixed in water and then dried, so that the degradable base material film material can be prepared.

9. The use according to claim 8, wherein the concentration ratio of the degradable substrate, the naphthalene anhydride derivative microencapsulated magnesium hydroxide composite powder is 1mol/L:1 to 30mol/L; the drying is carried out in two steps, wherein the temperature of the first step is 20-30 ℃, the drying time is 1-36 h, the temperature of the second step is 40-80 ℃, and the drying time is 1-36 h.