CN108384402B

CN108384402B - Nano zinc stannate flame retardant with core-shell structure and epoxy acrylate intumescent flame retardant coating with core-shell structure and phosphorus and nitrogen synergistic effect of nano zinc stannate flame retardant and phosphorus and nitrogen

Info

Publication number: CN108384402B
Application number: CN201810063830.7A
Authority: CN
Inventors: 杨磊; 林启; 郑炳云
Original assignee: Putian University
Current assignee: Fujian Haining Environmental Protection Technology Co.,Ltd.
Priority date: 2018-01-23
Filing date: 2018-01-23
Publication date: 2020-09-15
Anticipated expiration: 2038-01-23
Also published as: CN108384402A

Abstract

The invention discloses a nano zinc stannate flame retardant with a core-shell structure and an epoxy acrylate intumescent flame retardant coating with phosphorus and nitrogen synergistic with the nano zinc stannate flame retardant, wherein zinc ions and tin ions are reacted to prepare nano zinc stannate, nano inorganic flame retardant nano silicon dioxide is used as a matrix, a uniform precipitation method is utilized, ultrasonic dispersion and azeotropic distillation technologies are combined to coat the nano zinc stannate on the surface of the nano zinc stannate, a nano zinc stannate capsule with the core-shell structure is prepared, and the nano zinc stannate capsule is compounded with ammonium polyphosphate to prepare the phosphorus and nitrogen synergistic epoxy acrylate intumescent flame retardant coating containing zinc, tin and silicon, the flame retardant effect is good, the formation of a carbon layer can be effectively promoted, so that the flame retardant effect is improved, and the phosphorus and nitrogen synergistic epoxy acrylate intumescent flame retardant coating has good mechanical.

Description

Nano zinc stannate flame retardant with core-shell structure and epoxy acrylate intumescent flame retardant coating with core-shell structure and phosphorus and nitrogen synergistic effect of nano zinc stannate flame retardant and phosphorus and nitrogen

Technical Field

The invention belongs to the technical field of flame retardant coatings, and particularly relates to a nano zinc stannate flame retardant with a core-shell structure and an epoxy acrylate intumescent flame retardant coating with phosphorus and nitrogen synergistic with the nano zinc stannate flame retardant.

Background

The nano material is a material with a brand new structure developed in the middle of the 80 th year of the 20 th century and is known as the most promising material in the 21 st century. Particles having a particle diameter in the range of 1 to 100nm and in which a volume effect or a surface effect is observed are often referred to as nanoparticles. The nano additive is filled in the plastic, and can play a role in plasticizing and enhancing the rigid particles. This is because the flame-retardant effect is exerted by a chemical reaction, and the smaller the particle diameter, the larger the specific surface area and the better the flame-retardant effect for the same amount of flame retardant. On the other hand, the superfine and nano additives enhance the interaction of interfaces, can be more uniformly dispersed in matrix resin, and more effectively improve the mechanical property of the blend.

In recent years, tin and zinc compounds such as: the related researches on zinc stannate, zinc hydroxystannate and the like as the substitute of antimony trioxide are receiving more and more attention. Zinc stannate has non-toxic, harmless and good flame retardant and smoke suppressant properties, and has beneficial effects on halogens and fillers. But its application is limited due to its expensive price. Therefore, it is a target of flame retardant research workers to find a flame retardant which has excellent flame retardant smoke elimination performance and is lower in price than zinc hydroxystannate and zinc stannate while maintaining excellent performance of zinc hydroxystannate and zinc stannate.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a nano zinc stannate flame retardant with a core-shell structure and an epoxy acrylate intumescent flame retardant coating with phosphorus and nitrogen synergistic with the nano zinc stannate flame retardant.

One of the technical schemes adopted by the invention for solving the technical problems is as follows:

a preparation method of a nano zinc stannate flame retardant with a core-shell structure comprises the following steps:

1) mixing tin chloride and zinc chloride according to a molar ratio of 0.8-1.2: dissolving the raw materials into water according to the proportion of 0.8-1.2, dropwise adding a proper amount of acid to prevent stannic chloride from hydrolyzing, uniformly mixing, adjusting the pH value to 7.8-9.2, crystallizing at room temperature for 5-7 h, filtering, washing for a plurality of times at 65-75 ℃, and drying at 65-75 ℃ to obtain nano zinc stannate;

2) uniformly mixing nano zinc stannate with absolute ethyl alcohol, water and tween-80, and dropwise adding tetraethoxysilane, wherein the formula ratio of the nano zinc stannate to the absolute ethyl alcohol to the water to the tween-80 to the tetraethoxysilane is 9-11 g: 78-82 g: 9-11 mL: 0.08-0.12 g: 6.5-7.5 g, then adjusting the pH value to 7.8-8.2, keeping the temperature at 65-75 ℃, stirring and reacting for 2-4 h, cooling, filtering, washing and drying to obtain the nano zinc stannate with the core-shell structure.

In one embodiment: further comprising: in the step 1), sodium stearate is added into a system in which tin chloride and zinc chloride are dissolved in water, wherein the mass of the sodium stearate is 0.5-1.5% of the total mass of the tin chloride and the zinc chloride.

The second technical scheme adopted by the invention for solving the technical problems is as follows:

the nanometer zinc stannate flame retardant with the core-shell structure is prepared according to the preparation method.

The third technical scheme adopted by the invention for solving the technical problems is as follows:

a preparation method of an epoxy acrylate intumescent flame retardant coating comprises the following steps: sequentially and one by one adding acrylic acid, APP, the nano zinc stannate flame retardant with the core-shell structure and epoxy acrylate into acrylamide, wherein the mass ratio of the acrylic acid to the acrylamide to the APP to the nano zinc stannate flame retardant with the core-shell structure to the epoxy acrylate is 1.8-2.2: 1.4-1.6: 0.8-2.2: 0.2-1.2: 3.2-5.5, and uniformly mixing and eliminating bubbles when adding the epoxy acrylate intumescent flame retardant coating every time to obtain the epoxy acrylate intumescent flame retardant coating.

In one embodiment: further comprising: the nano zinc stannate flame retardant with the core-shell structure is prepared according to the preparation method.

In one embodiment: the mass ratio of the acrylamide, the acrylic acid, the APP, the nano zinc stannate flame retardant with the core-shell structure and the epoxy acrylate is 2: 1.5: 2: 1: 3.5.

in one embodiment: further comprising: and finally adding an initiator accounting for 2-4% of the total mass of the system.

In one embodiment: the initiator is a photoinitiator 1173.

The fourth technical scheme adopted by the invention for solving the technical problems is as follows:

the epoxy acrylate intumescent flame retardant coating prepared by the preparation method.

Compared with the background technology, the technical scheme has the following advantages:

according to the invention, zinc ions and tin ions are reacted to prepare nano zinc stannate, a nano inorganic flame retardant (nano silicon dioxide) is used as a matrix, a uniform precipitation method is utilized, ultrasonic dispersion and azeotropic distillation technologies are combined, nano zinc stannate is coated on the surface of the nano zinc stannate capsule to prepare the nano zinc stannate capsule with a core-shell structure, and the nano zinc stannate capsule is compounded with ammonium polyphosphate to prepare the phosphorus-nitrogen synergistic epoxy acrylate intumescent flame retardant coating containing zinc, tin and silicon, so that the flame retardant effect is good, the formation of a carbon layer can be effectively promoted, the flame retardant effect is improved, and the nano zinc stannate capsule has good mechanical, optical and thermal stability, and can meet the requirements of the current flame retardant.

Drawings

The invention is further illustrated by the following figures and examples.

FIG. 1 shows NXSX and NSiXSX IR spectra (at room temperature) (a-NSiXSX IR spectrum; b-NXSX IR spectrum).

FIG. 2 is a blank set of real-time IR spectra (100-220 ℃ C.).

FIG. 3 is a blank set of real-time infrared spectra (230-280 ℃).

FIG. 4 is a blank set of real-time infrared spectra (290-450 ℃ C.).

FIG. 5 is a real-time infrared spectrum (100-210 ℃ C.) of the NXSX/EA coating (sample 4).

FIG. 6 is a real-time infrared spectrum (220-280 ℃) of the NXSX/EA coating (sample 4).

FIG. 7 is a real-time infrared spectrum (290 ℃ -450 ℃) of the NXSX/EA coating (sample 4).

FIG. 8 is a real-time infrared spectrum (100-210 ℃ C.) of the APP/EA coating (sample 20).

FIG. 9 is a real-time infrared spectrum (220-280 ℃) of the APP/EA coating (sample 20).

FIG. 10 is a real-time infrared spectrum (290-450 ℃) of the APP/EA coating (sample 20).

FIG. 11 is a real-time infrared spectrum (100-210 ℃) of APP/HPNSiSCX/EA coating (sample 40).

FIG. 12 is a real-time infrared spectrum (220-280 ℃) of APP/HPNSiSCX/EA/EA coating (sample 40).

FIG. 13 is a real-time infrared spectrum (290-450 ℃) of APP/HPNSiXSX/EA/EA coating (sample 40).

FIG. 14 is a UV spectrum of a UV cured coating of an NXSX/EA flame retardant system.

FIG. 15 is a UV spectrum of a UV cured coating of a HPNXSX/EA flame retardant system.

FIG. 16 is a UV spectrum of a UV cured coating of a NSiXSX/EA flame retardant system.

FIG. 17 is a UV spectrum of a UV cured coating of a HPNSiXSX/EA flame retardant system.

FIG. 18 is a UV spectrum of a UV cured coating of an APP/EA flame retardant system.

FIG. 19 is a UV spectrum of a UV cured coating of an APP/NXSX/EA flame retardant system.

FIG. 20 is a UV spectrum of a UV cured coating of an APP/HPNXSX/EA flame retardant system.

FIG. 21 is a UV spectrum of a UV cured coating of an APP/NSiXSX/EA flame retardant system.

FIG. 22 is a UV spectrum of a UV cured coating of an APP/HPNSiSCX/EA flame retardant system.

FIG. 23 is a thermogram of NXSX/EA flame retardant coating (a-sample 1; b-sample 2; c-sample 3; d-sample 4).

FIG. 24 is a thermogram of APP/EA flame retardant coating (a-sample 17; b-sample 18; c-sample 19; d-sample 20).

FIG. 25 is a thermogram of APP/NSiXSX/EA flame retardant coating (a-sample 31; b-sample 32; c-sample 33; d-sample 34; e-sample 35).

FIG. 26 is a thermogram of APP/HPNSiSCX/EA flame retardant coating (a-sample 36; b-sample 37; c-sample 38; d-sample 39; e-sample 40).

FIG. 27 is an electron microscope image of nano zinc stannate (NXSX) (FIG. 27A, scale 50nm), organized nano zinc stannate (HPNXSX) (FIG. 27B, scale 100nm), and nano zinc stannate capsules (NSiXSX) (FIG. 27C, scale 100 nm).

Detailed Description

The present invention will be described in detail with reference to the following examples:

example 1: preparation of nano zinc stannate (NXSX)

0.02M SnC1₄·5H₂O and 0.02M ZnC1₂·3H₂Dissolving O in 300ml distilled water, and dropwise adding an appropriate amount of 1mol/L hydrochloric acid solution to prevent SnC1₄·5H₂And hydrolyzing, adding a proper amount of NaOH after the mixed solution is uniformly stirred, strongly stirring while adding to ensure that the final pH values of the reaction system are respectively 8-9, crystallizing at room temperature for 6 hours, filtering the precipitate, centrifugally washing with 70 ℃ distilled water for three times, then putting into a 70 ℃ oven for drying, and grinding for later use to obtain the nano zinc stannate, which is recorded as NXSX.

Example 2: preparation of organic nano zinc stannate (HPNXSX)

0.02M SnC1₄·5H₂O and 0.02M ZnC1₂·3H₂O, and 1% sodium stearate in 300ml distilled water, and appropriate 1mol/L hydrochloric acid solution is added dropwise to prevent SnC1₄·5H₂Hydrolyzing, adding a proper amount of alkali after uniformly stirring the mixed solution, strongly stirring while adding to ensure that the final pH value of the reaction system is 8-9 respectively, crystallizing at room temperature for 6h, filtering the precipitate, centrifugally washing with 70 ℃ distilled water for three times, then putting into a 70 ℃ oven for drying, and grinding for later use to obtain organic nano zinc stannate (sodium stearate nano zinc stannate) which is recorded as HPNXSX.

Example 3: preparation of nano zinc stannate capsule (NSiXSX)

Weighing 10g of the nano zinc stannate prepared in the embodiment 1, 80g of absolute ethyl alcohol, 10mL of water and 0.1g of Tween-80, adding the nano zinc stannate, 80g of absolute ethyl alcohol, 10mL of water and 0.1g of Tween-80 into a three-necked bottle, quickly stirring for 30min, dropwise adding 7g of tetraethoxysilane, then adjusting the pH of a reaction solution to be about 8 by using ammonia water, heating to 70 ℃, keeping the temperature, stirring for reaction for 3h, cooling, filtering, washing and drying to obtain the nano zinc stannate capsule with the core-shell structure, and marking as.

Example 4: preparation of organic nano zinc stannate capsule (HPNSiSXX)

Weighing 10g of sodium stearate nano zinc stannate prepared in the embodiment 2, 80g of absolute ethyl alcohol, 10mL of water and 0.1g of Tween-80, adding the sodium stearate nano zinc stannate, 80g of absolute ethyl alcohol, 10mL of water and 0.1g of Tween-80 into a three-necked bottle, quickly stirring for 30min, dropwise adding 7g of tetraethoxysilane, then adjusting the pH of a reaction solution to be about 8 by using ammonia water, heating to 70 ℃, keeping the temperature, stirring for reaction for 3h, cooling, filtering, washing and drying to obtain the organic nano zinc stannate capsule with the core-shell structure, which is recorded.

Example 5: preparation of UV-curable EA coatings

The UV curing EA coating is prepared by respectively adopting nano zinc stannate, organic nano zinc stannate, nano zinc stannate capsules and organic nano zinc stannate capsules, and then by respectively adopting nano zinc stannate, organic nano zinc stannate, nano zinc stannate capsules, organic nano zinc stannate capsules and APP for compounding.

According to the formula shown in tables 1-9, the ultraviolet curing coating with the total mass of 10g is prepared according to the formula, about 3% of 1173 photoinitiator is added, various active monomers are added according to the following different proportions, and the adding sequence is as follows: adding acrylic acid, ammonium polyphosphate (APP) (if any), nano zinc stannate flame retardant with a core-shell structure (if any) and Epoxy Acrylate (EA) into acrylamide one by one in sequence, uniformly stirring each time of adding materials, and then carrying out ultrasonic oscillation for a period of time to eliminate bubbles and uniformly disperse the bubbles. Finally, photoinitiator 1173 is added. The coating was prepared by coating a glass plate with a 100 μm SZQ preparation with a 100 μm coating thickness of about 100 μm, curing with a portable UV curing light source, and irradiating for a period of time to cure the coating to a film. The strips were prepared by pouring the sample into a mold of a certain length and width, filling the entire mold, and then curing it into strips with a hand-held UV curing machine.

1) Preparation of NXSX/EA flame-retardant coating

TABLE 1 UV-CURABLE NXSX/EA FLAME RETARDANT COATING FORMULATIONS

2) Preparation of HPNXSX/EA flame-retardant coating

TABLE 2 UV-CURABLE HPNXSX/EA FLAME RETARDANT COATING FORMULATIONS

3) Preparation of NSiXSX/EA flame-retardant coating

TABLE 3 UV-CURABLE NSiXSX/EA FLAME RETARDANT COATING FORMULATIONS

4) Preparation of HPNSiXSX/EA flame-retardant coating

TABLE 4 UV-CURABLE HPNSiSCX/EA FLAME RETARDANT COATING FORMULATIONS

5) Preparation of APP/EA flame-retardant coating

TABLE 5 UV-CURABLE APP/EA FLAME RETARDANT COATING FORMULATIONS

6) Preparation of APP/NSXS/EA flame-retardant coating

TABLE 6 UV-CURABLE APP/NSXS/EA FLAME RETARDANT COATING FORMULATIONS

7) Preparation of APP/HPNSXS/EA flame-retardant coating

TABLE 7 UV-CURABLE APP/HPNSXS/EA FLAME RETARDANT COATING FORMULATIONS

8) Preparation of APP/NSiXSX/EA flame-retardant coating

TABLE 8 UV-CURABLE APP/NSiXSX/EA FLAME RETARDANT COATING FORMULATIONS

9) Preparation of APP/HPNSiSCX/EA flame-retardant coating

TABLE 9 UV-CURABLE APP/HPNSiSCX/EA FLAME RETARDANT COATING FORMULATIONS

The above examples were used in the following experimental examples:

experimental example 1: determination of coating transmittance

The transmittance of the coating prepared in example 5 was measured using an ultraviolet-visible spectrophotometer model number Shimadzu UV-2250, manufactured by JEOL. And placing the coating with a certain size in a cuvette, and setting the ultraviolet curing wavelength range of the coating to be 190-800 nm. And analyzing the light transmittance of the coating by measuring the transmission spectrum of the coating in the wavelength range of 190-800 nm.

Experimental example 2: measurement of coating hardness

Fixing the cured coating on a testing instrument, measuring the hardness of the coating according to the standard of GB/T6739, wherein pencils are selected from low to high, the pencils are arranged on a propeller to form an angle of 45 degrees according to requirements during measurement, then the pencils are propelled at the speed of about 1mm/s, each pencil with hardness grade draws five lines on the coating, and when five scratches of the pencils with certain hardness cannot be seen and the scratches of the pencils with hardness can be seen later, the hardness of the pencils is the hardness of the coating.

Experimental example 3: determination of coating carbon residue

When the carbon residue rate is measured, a sample to be measured is weighed, the sample is combusted in the air, the carbon residue rate is measured after the combustion is finished, and the expansion index and the like are judged.

m₁、m₂Respectively the mass of the material before and after combustion.

Experimental example 4: coating limiting oxygen index determination

And testing the limit oxygen index of the coating by using an oxygen index measuring instrument of HC-2 type. Placing the sample in N₂And O₂The test was performed in an experimental environment with the coating vertically placed on top for combustion. The measurement was carried out on an oxygen index meter by ASTM D2863-77 standard.

Experimental example 5: vertical burning test

Performing combustion measurement on the coating according to UL 94-2006 series standard by adopting a vertical/horizontal combustion testing machine of YCCT6022 type; the coating was subjected to combustion measurement using a muffle furnace of type a4100248 manufactured by samson technologies ltd, shanghai, and a sample of a certain size was placed in a crucible at a set rate of 20 ℃/min and a final temperature of 500 ℃, and then the crucible was placed in a furnace for calcination.

Experimental example 6: thermogravimetric (TG) analysis

The samples were analyzed with a Nanjing large scale thermogravimetric analyzer. The temperature is controlled between room temperature and 800 ℃, the heating rate is 10 ℃/min, and the measurement is carried out in the air.

Experimental example 7: infrared analysis of photocured coatings

Grinding a small amount of solid sample in a mortar, adding a certain amount of KBr, mixing, uniformly grinding, tabletting and forming in a tabletting machine, and measuring in a Fourier infrared spectrometer (model Nicolet 380 FT-IR).

The results of the above experimental examples are as follows:

1. core-shell structure nano zinc stannate morphology

FIG. 27 is an electron microscope image of nano zinc stannate (NXSX), organized nano zinc stannate (HPNXSX) and nano zinc stannate capsules (NSiXSX). It can be seen that the nano zinc stannate capsule (NSiXSX) prepared by the experiment has a core-shell structure and the particle size is about 200nm, and the particle sizes of the zinc stannate (NXSX) and the organic nano zinc stannate (HPNXSX) are about 50nm and 100nm respectively.

2. Infrared analysis

FIG. 1 shows the IR spectra at room temperature for NXSX (b in FIG. 1) and NSiXSX (a in FIG. 1), as seen in FIG. 1, at 3370cm^-1Is a characteristic absorption peak of-OH at 2300cm^-1Is treated with CO₂Absorption peak of 1380cm^-1At 1180cm, which is a bending vibration absorption peak of Sn-OH^-11630cm as the bending vibration absorption peak of Zn-OH^-1The peak of the absorption of the vibration is water, and may be related to the absorption of water vapor by air contact during tabletting. Compared with b, a has two more peaks at 1090m respectively^-1At and 845cm^-1At 1090cm^-1The peak at (A) is the antisymmetric telescopic peak of Si-O-Si, and 845cm^-1The position is a symmetric stretching vibration peak of Si-O, so that the experiment proves that the nano zinc stannate NSiXSX with the core-shell structure is successfully synthesized.

FIG. 2, FIG. 3 and FIG. 4 are blank set real-time infrared spectra, 3440cm^-1The characteristic peak of-OH is smaller and smaller with the temperature rise, and disappears completely at 420 ℃, which indicates that the characteristic peak of-OH is degraded completely. 2970cm^-1And 2870cm^-1Is C-H₃And C-H₂The peak of (a) was almost unchanged before 390 ℃, and then the degradation was complete at 420 ℃ with increasing temperature. At 2350cm^-1Is treated with CO₂An absorption peak, also present after 450 ℃ at 1730cm^-1The absorption peak at C ═ O indicates that C ═ O is present in the product and that the degradation is complete at 390 ℃ with decreasing temperature. 1670cm^-1The peak is the shock absorption of water and then evaporates completely at 390 ℃ with increasing temperature. 1600cm^-1Where is the characteristic absorption peak of the fused ring compound formed, 1520cm^-1Is a characteristic peak of acrylamide N-H, gradually degrades along with the temperature rise, and completely degrades at 390 ℃. 1390cm^-1is-CH₂The bending vibration peak of the-CH gradually degrades along with the temperature rise, and the degradation is complete at 390 ℃. 1040cm^-1Is CH ═ CH₂Has an absorption peak of 830cm which is almost unchanged until 450 DEG C^-1The peak is a benzene ring and is completely degraded after 420 ℃.

FIGS. 5, 6 and 7 are real-time infrared spectra of NXSX/EA coatings (sample 4) of 3350cm^-1The characteristic peak of-OH is smaller and smaller with the temperature rise, and disappears completely at 420 ℃, which indicates that the characteristic peak of-OH is degraded completely. 2950cm^-1And 2860cm^-1Is C-H₃And C-H₂The peak of (a) was almost unchanged before 390 ℃, and then the degradation was complete at 390 ℃ with an increase in temperature. At 2370cm^-1Is treated with CO₂Absorption peaks and then complete degradation at 420 ℃ with increasing temperature. At 1730cm^-1Where is the absorption peak of C ═ O, indicating that C ═ O is present in the product, degradation is complete at 390 ℃ with decreasing temperature, the upslope in the figure being due to CO impurity₂The influence of (c). 1660cm^-1The vibration absorption peak of water still exists after 450 ℃, 1600cm^-1There is a characteristic absorption peak of the fused ring compound formed, indicating the generation of a carbon layer after the coating was burned, 1510cm^-1Is a characteristic peak of acrylamide N-H, gradually degrades along with the temperature rise, and completely degrades at 390 ℃. 1390cm^-1is-CH₂The bending vibration peak of the-CH gradually degrades along with the temperature rise, and the degradation is complete at 390 ℃. 1240cm^-1Bending vibration absorption peak at Sn-OH, 1170cm^-1The peak is the bending vibration absorption peak of Zn-OH, and the two are completely degraded at 360 ℃. 1040cm^-1The peak at (B) is the antisymmetric telescopic peak of Si-O-Si, 830cm^-1The vibration peak is the symmetrical stretching vibration peak of Si-O. In conclusion, the coating has good thermal stability and slow degradation speed, and the zinc stannate is completely degraded at 360 ℃ to form a good flame-retardant carbon layer.

FIGS. 8, 9 and 10 are real-time infrared spectra of APP/EA coatings (sample 20), 3450cm^-1The characteristic peak of-OH at the position is smaller and smaller with the temperature rise, and disappears completely at 280 ℃, which indicates that-OH is degraded completely. 3210cm^-1The peak is the characteristic peak of ammonium polyphosphate-NH, which is smaller and smaller along with the temperature rise and completely disappears at 270 ℃, which indicates that-NH is completely degraded. 2980cm^-1And 2880cm^-1Is C-H₃And C-H₂The peak of (a) was almost unchanged before 260 ℃ and then degraded completely at 270 ℃ with increasing temperature. At 2360cm^-1Is treated with CO₂The absorption peak, which was almost unchanged before 260 ℃ and then degraded completely at 270 ℃ with increasing temperature, was 1730cm^-1The peak is the absorption peak of C ═ O, which indicates that C ═ O exists in the product, and the degradation is complete at 290 ℃ as the temperature becomes lower, and the upslope in the figure is due to the impurity CO₂The influence of (c). 1660cm^-1The peak is the shock absorption of water, and then the degradation is complete at 390 ℃ with the increase of temperature. 1600cm^-1Here is a characteristic absorption peak of the fused ring compound formed, indicating the generation of a carbon layer upon combustion, 1510cm^-1Is a characteristic peak of acrylamide N-H, gradually degrades along with the temperature rise, and completely degrades at 290 ℃. 1390cm^-1is-CH₂The bending vibration peak with-CH, also present after 450 ℃. 1250cm^-1Is a characteristic absorption peak of-P ═ O, 1190cm^-1、900cm^-1Is a characteristic absorption peak of-C-O-P. 1040cm^-1Is CH ═ CH₂The absorption peak of (A) is gradually degraded along with the temperature rise, and is completely degraded at 360 ℃ and is 830cm^-1The peak is a benzene ring and is completely degraded after 420 ℃. In conclusion, the coating has general thermal stability and high degradation speed, and the ammonium polyphosphate is completely degraded at 260 ℃ to form a good flame-retardant carbon layer.

FIG. 11, FIG. 12 and FIG. 13 are APP/HPNSiXSReal-time infrared spectrogram of X/EA coating (sample 40), 3440cm^-1The characteristic peak of-OH at the position is smaller and smaller with the temperature rise, and disappears completely at 280 ℃, which indicates that-OH is degraded completely. 3200cm^-1The peak is the characteristic peak of ammonium polyphosphate-NH, which is smaller and smaller along with the temperature rise and completely disappears at 360 ℃, which indicates that-NH is completely degraded. 2950cm^-1And 2860cm^-1is-CH₃and-CH₂The peak of (a) was almost unchanged before 330 ℃ and then degraded completely at 360 ℃ with increasing temperature. At 2360cm^-1Is treated with CO₂The absorption peak, which was almost unchanged before 360 ℃ and then degraded completely at 390 ℃ with increasing temperature, at 1730cm^-1The peak is the absorption peak of C ═ O, which indicates that C ═ O exists in the product, and the degradation is complete at 360 ℃ as the temperature becomes lower, and the upslope in the graph is due to the impurity CO₂The influence of (c). 1660cm^-1The peak is the shock absorption of water and then evaporates completely at 290 ℃ with increasing temperature. 1600cm^-1Here is a characteristic absorption peak of the fused ring compound formed, indicating the generation of a carbon layer upon combustion, 1510cm^-1Is a characteristic peak of acrylamide N-H, gradually degrades along with the temperature rise, and completely degrades at 360 ℃. 1390cm^-1is-CH₂And the bending vibration peak of-CH is completely degraded at 450 ℃. 1260cm^-1The characteristic absorption front of-P ═ O may also overlap with the bending vibration absorption peak of Sn-OH, 1190cm^-1、883cm^-1Is a characteristic absorption peak of-C-O-P, 1190cm^-1Possibly the bending vibration absorption peak of Zn-OH; 1125cm^-1Is the absorption peak of Si-O-Zn at 1020cm^-1Is CH ═ CH₂The absorption peak of (A) may overlap with that of Si-O-Si, and gradually degrade with increasing temperature, and completely degrade at 360 deg.C (830 cm)^-1The peak at the benzene ring can also be a symmetrical stretching vibration peak of Si-O, and is completely degraded after 330 ℃. As can be seen from the figure, after the APP and the HPNSiSCX are compounded, the flame retardance of the APP and the HPNSiSXX is improved and can be degraded only after 450 ℃, and the HPNSiSXX is completely degraded after 360 ℃, so that the APP/HPNSiSXX/EA coating is added, the thermal stability is good, the degradation speed is slow, the degradation is complete at 290 ℃, and a good flame-retardant carbon layer can be formed,the flame retardant effect of the coating is improved.

3. Spectral analysis

FIG. 14 is a UV-VIS spectrum of a UV cured coating of an NXSX/EA flame retardant system. As can be seen, the transmittance of the coating in the visible light region decreases with increasing NXSX content, and the decrease in transmittance is significant at an NXSX content of 10%, indicating that the NXSX content can decrease the transmittance of the coating, but the uv-shielding ability increases with increasing NXSX content.

FIG. 15 is a UV-vis spectrum of a UV cured coating of a HPNXSX/EA flame retardant system. As can be seen, the transmittance of the coating in the visible light region decreased with increasing HPNXSX content, indicating that HPNXSX can decrease the light transmittance of the coating, but its uv-shielding ability increased with increasing HPNXSX content.

FIG. 16 is a UV-VIS spectrum of a UV cured coating of a NSiXSX/EA flame retardant system. As can be seen, the transmittance of the coating in the visible light region decreases with increasing NSiXSX content, but the uv-shielding ability increases with increasing NSiXSX content. When the content of the flame-retardant monomer is 3%, the higher the light transmittance of the coating is, the higher the light transmittance can be, the more than 85%. When the content of the flame retardant monomer NSiXSX is 10%, the light transmittance of the coating is obviously reduced, and compared with that of fig. 13, the transmittance of NSiXSX is higher, probably because the introduced tetraethoxysilane can provide Si ions, so that the transmittance is increased, which indicates that the content of the flame retardant monomer NSiXSX has a larger influence on the light transmittance of the coating, but the ultraviolet shielding capability of the coating is increased along with the increase of the content of NSiXSX.

FIG. 17 is a UV-vis spectrum of a UV-cured coating of a HPNSiXSX/EA flame retardant system. When the content of the flame-retardant monomer HPNSiXSX is 3%, the higher the light transmittance of the coating is, the light transmittance can reach more than 80%, and when the content of the flame-retardant monomer HPNSiXSX is less than 7%, the light transmittance is more than 50%. When the flame-retardant monomer HPNSiXSX is 10%, the light transmittance of the coating is obviously reduced and is lower than 50%, which shows that the content of the flame-retardant monomer HPNSiXSX has large influence on the light transmittance of the coating and is changed regularly.

FIG. 18 is a UV-vis spectrum of a UV cured coating of an APP/EA flame retardant system. When fire-retardant monomer APP content when 5%, the luminousness of coating is higher, can reach more than 90%, and when fire-retardant monomer APP content was below 15%, the luminousness all was greater than 80%, and when fire-retardant monomer APP content was at 20%, the luminousness still was greater than 75%, showed: the content of APP has little influence on the light transmittance, and the light transmittance is high. In a visible light area of 470-800 nm, the light transmittance of each system is equivalent, the light transmittance is over 70 percent, and the visible coating has good light transmittance.

FIG. 19 is a UV-vis spectrum of a UV-cured coating of an APP/NXSX/EA flame retardant system. As can be seen, the transmittance of the coating in the visible light region decreases with increasing NXSX content when the APP content is constant, and decreases significantly with 10% APP content and 7% NXSX content, while decreasing to 7% APP content and 10% NXSX content, indicating that NXSX can decrease the transmittance of the coating, but does not change significantly with APP. The UV-screening ability increases with increasing NXSX content, but the effect is less with APP.

FIG. 20 is a UV-vis spectrum of a UV-cured coating of an APP/HPNXSX/EA flame retardant system. When the amount of APP is 10%, the transmittance is continuously decreased as the mass of the flame retardant monomer HPNXSX is increased, and when the amount of HPNXSX is 5% or more, the transmittance is significantly decreased, and when the amount of APP is increased to 20% and the amount of HPNXSX is 10%, the transmittance is substantially zero, as shown in fig. 13 and 16, when the amount of HPNXSX is 10%, the transmittance is 20%, and when the amount of ammonium polyphosphate is 20%, the transmittance is 78%, thereby showing that the main factor affecting the transmittance is HPNXSX.

FIG. 21 is a UV-vis spectrum of a UV-cured coating of an APP/NSiXSX/EA flame retardant system. As can be seen from the graph, as the content of APP is constant, the NSiXSX content is increased from 3% to 5%, the transmittance is substantially constant, and is maintained at about 85%, and when the NSiXSX content is continuously increased, the transmittance is significantly decreased, and when the content of APP is increased to 20% and the NSiXSX content is 10%, the transmittance is decreased to 40%, as can be seen from fig. 14 and 16, the transmittance is decreased by increasing the NSiXSX content, but is not decreased much, and the influence of APP is not great, but compared with fig. 19, the transmittance is increased by the presence of NSiXSX. This indicates that NSiXSX can reduce the light transmission of the coating, but does not change significantly with APP.

FIG. 22 is a UV-vis spectrum of a UV-cured coating of an APP/HPNSiSCX/EA/EA flame retardant system. When the amount of APP is 10%, the transmittance decreases with the increase of the flame retardant monomer HPNSiXSX, and changes regularly, as shown in fig. 15 and 16, only when the content of HPNSiXSX is 3%, the transmittance exceeds 50%, as shown in fig. 20, HPNSiXSX decreases the transmittance by about 30%, but the uv-shielding ability increases with the increase of the content of HPNSiXSX.

4. Analysis of flame retardancy

1) Limiting oxygen index and vertical burning result of EA photocuring flame-retardant coating

TABLE 10EA Limited oxygen index and vertical burn results for photocured flame retardant coatings

1-4 of the NXSX/EA photocuring flame-retardant coating are the limiting oxygen index and the vertical combustion result, the LOI value and UL-94 are increased along with the increase of the NXSX content, the LOI can reach 31, the combustion level can reach V-0, and the hardness is 5H, probably because the EA content is reduced along with the increase of the NXSX content, the NXSX is easy to degrade during heating to generate active Zn and Sn, and the active Zn and Sn have a catalytic char formation effect on the combustion of a polymer, when the polymer degrades, the char formation can be rapidly realized, the char yield is improved, and meanwhile, the gas generated by a gas source expands a carbon layer to form an expanded flame-retardant carbon layer, so the LOI value and UL-94 are increased.

5-8 are the limiting oxygen index and the vertical combustion result of the light-cured flame-retardant coating of HPNXSX/EA, as the content of HPNXSX increases, the LOI value and UL-94 are increased, the LOI can reach 31, the hardness is 5H, and the combustion level can reach V-0, because 1% of sodium stearate can make the particle size of NXSX smaller, which is beneficial to increasing the contact area of the coating to EA, and can promote the polymer to form carbon, thereby improving the flame retardant property of the coating and increasing the LOI value and UL-94.

9-12 are the limiting oxygen index and the vertical combustion result of the photocuring flame-retardant coating of NSiXSX/EA, the LOI value and UL-94 are increased gradually with the increase of the content of NSiXSX, the LOI can reach 32, the combustion level can reach V-0, and the hardness is 6H, because Si-O bonds and Si-C bonds exist in a NSiXSX/EA system, a substance (silicate) generated after degradation can cover the surface of the coating, the hardness and the compactness of a carbon layer are increased, the coating is protected, a good flame-retardant effect can be achieved, and the LOI value and UL-94 are increased.

13-16 are the limiting oxygen index and the vertical burning result of the light-cured flame-retardant coating of HPNSiXSX/EA, as the content of HPNSiXSX increases, the LOI value and UL-94 are increased, the LOI can reach 32, the burning grade can reach V-0, and the hardness is 6H, and compared with 9-12 groups, 1% of sodium stearate can improve the LOI value and UL-94 of NSiXSX when the content is lower, and when the content is further improved, the improvement of the LOI value and UL-94 is more unobvious. It can be shown that the active Zn and Sn after increasing the content has a greater influence on the flame retardant properties of the coating than sodium stearate. And comparing with 5-8, it is known that when the content of HPNSiXSX is small, the flame retardant effect is not improved obviously, and when the content of HPNSiXSX is 7%, LOI and UL-94 are increased.

17 ~ 20 are limit oxygen index and perpendicular burning result of the photocuring fire-retardant coating of APP/EA, along with the increase of APP content, its LOI value and UL-94 increase progressively, and LOI can reach 32, and the burning rank can reach V-0, and hardness is 6H, because under high temperature, APP promotes the formation of charcoal layer, and nitrogen element can impel the coating inflation, can form inflation fire-retardant charcoal layer, has good shielding effect to oxygen and heat, is favorable to improving the fire behaviour of coating.

21 to 25 are the limiting oxygen index and the vertical burning result of the light-cured flame-retardant coating of APP/NXSX/EA, when the APP content is not changed, along with the increase of the NXSX content, the LOI value and UL-94 are increased, when the APP content is 20 percent and the NXSX content is 10 percent, the LOI value of the alloy reaches 33 at most, the combustion level can reach V-0, the hardness is 6H, because NXSX is easy to degrade to generate active Zn and Sn when being heated, and the active Zn and Sn have catalytic char formation effect on the combustion of the polymer, when the polymer is degraded, the polymer can rapidly form char, meanwhile, the gas generated by the gas source expands the carbon layer to form an expanded flame-retardant carbon layer, so that the carbon residue rate is improved, and APP promotes the generation of the carbon layer, nitrogen elements promote the expansion of the coating, an expansion flame-retardant carbon layer is formed, has good shielding effect on oxygen and heat, is beneficial to improving the flame retardant property of the coating, and increases the LOI value and UL-94.

26-30 are the limiting oxygen index and the vertical combustion result of the light-cured flame-retardant coating of APP/HPNXSX/EA, when the APP content is unchanged, the LOI value and UL-94 are increased along with the increase of the HPNXSX content, when the APP content is 20% and the HPNXSX content is 10%, the LOI value reaches the highest 34, the combustion grade can reach V-0, the hardness is 6H, and compared with 21-25, the LOI value is improved because the particle size of the HPNXSX is thinned by 1% of sodium stearate, the contact area of the HPNXSX to EA is favorably increased, the polymer is more favorably carbonized, the flame retardant property of the coating is improved, and the LOI value and UL-94 are increased.

31-35 are the limiting oxygen index and the vertical combustion result of the light-cured flame-retardant coating of APP/NSiXSX/EA, when the APP content is unchanged, the LOI value and UL-94 are increased along with the increase of the NSiXSX content, when the APP content is 20% and the NSiXSX content is 10%, the LOI value is up to 34, the combustion level can reach V-0, the hardness is 6H, Si-O bonds and Si-C bonds may exist in a NSiXSX/EA system, substances (silicate) generated after degradation can cover the surface of the coating, the hardness and the compactness of the carbon layer are increased, the coating is protected, the APP element promotes the generation of the carbon layer, the nitrogen element promotes the expansion of the coating, an expanded flame-retardant carbon layer can be formed, a good shielding effect on oxygen and heat is achieved, the flame-retardant performance of the coating is improved, and the LOI value and UL-94 are increased.

36-40 of the limiting oxygen index and the vertical burning result of the photo-cured flame-retardant coating with APP/HPNSiXSX/EA, it can be seen that in the presence of HPNSiXSX, when the content of APP is 10% and the content of HPNSiXSX is less than 10%, the LOI index is obviously improved, but when the content of APP is 20% and the content of HPNSiXSX is 10%, the LOI index is not obviously improved, the LOI value reaches up to 35, the burning grade can reach V-0, and the hardness is 6H, probably because when the content of APP is 10%, the content of HPNSiXSX is mainly a key factor determining the LOI index, but when the content of APP is improved, the APP replaces HPNSiXSX to become the most important factor determining the LOI index.

As shown in Table 10, the hardness of each photo-cured flame-retardant coating is above 5H, because the added flame retardant is nano-scale rigid particles which can act as physical cross-linking points and improve the Tg temperature and hardness of the system coating, especially the added SiO₂Thereafter, the hardness of each coating was 6H.

In conclusion, with the addition of flame retardants such as NXSX, APP, NSiXSX, HPNXSX, HPNSiXSX and the like, the LOI value and the vertical burning grade are both obviously improved, namely the flame retardance of the coating film is obviously improved. And the vertical burning grades are all above V-1 and basically reach V-0. In the APP/HPNSiSCX/EA system, when the APP content is 20% and the HPNSiSCX content is 10%, the LOI value can reach 35 at most, UL-94 can reach V-0, and the hardness is 6H.

TABLE 11 EA photocuring flame retardant coating char yield

1-4 of the photocuring flame-retardant coating with an NXSX/EA system, wherein the carbon residue rate is increased along with the increase of the NXSX content as seen from a combustion result at room temperature, and the carbon residue rate can reach 28.4% at most when the NXSX content is 10%, because the NXSX is easy to degrade during heating to generate active Zn and Sn, and the active Zn and Sn have a catalytic carbon formation effect on the combustion of a polymer, and can rapidly form carbon when the polymer is degraded, so that the carbon residue rate is improved; as a result of combustion in a muffle furnace (500 ℃ C.), it was found that the char yield was comparable to that of combustion at room temperature.

5-8 are photocuring flame-retardant coatings of HPNXSX/EA systems, and the carbon residue rate is increased along with the increase of the content of HPNXSX as shown by a combustion result at room temperature, and when the content of HPNXSX is 10%, the carbon residue rate can be up to 28.9%, and when the content of HPNXSX is compared with 1-4, the carbon residue rate can be increased by 1% of sodium stearate. It can be seen from table 11 that the carbon residue rate of the muffle furnace is lower than that at normal temperature when the HPNXSX content is relatively low, and then the carbon residue rate gradually increases with the increase of the HPNXSX content, even exceeds the carbon residue rate of combustion at normal temperature, because the particle size of NXSX becomes fine by 1% sodium stearate, which is beneficial to increasing the contact area of the NXSX with EA, and can promote the polymer to form carbon, thereby improving the flame retardant property of the coating and increasing the carbon residue rate.

9-16 are light-cured flame-retardant coatings of a NSiXSX/EA system and a HPNSiXSX/EA system, and the combustion result at room temperature shows that the carbon residue rate increases with the increase of the contents of the NSiXSX and the HPNSiXSX, the carbon residue rate can reach 32.6% at the maximum when the content of the NSiXSX is 10%, the carbon residue rate can reach 33.6% at the maximum when the content of the HPNSiXSX is 10%, and the comparison of 1-4 and 5-8 shows that the SiO prepared from the tetraethoxysilane₂The shell structure can improve the carbon residue rate, and the carbon residue rate obtained by calcining in the muffle furnace is slightly lower than that obtained by calcining at normal temperature, but the change trend is basically consistent. The reasons may be as follows: firstly, the organosilicon flame retardant has good thermal stability, which is determined by Si-O-C bond of molecular main chain; secondly, siloxane can generate Si-C bonds during combustion to isolate oxygen from contacting with the coating, so that the flame retardant effect is achieved; thirdly, after the flame retardant is burnt, the coating layer expands rapidly to form an expanded carbon layer which covers the surface layer of the substrate to play a role in protecting the flame-retardant substrate.

17 ~ 20 are photocuring flame retardant coating of APP/EA system, the result of burning under the room temperature can be seen out that the carbon residue rate increases along with the increase of APP content, and when APP content be 10% the carbon residue rate can reach 35.4% at most, and the carbon residue rate in the muffle furnace is 41.5%, than the height at ordinary temperature, this probably because the coating is heated softly easily under high temperature, APP can promote the formation of carbon layer, nitrogen element can make the coating inflation, the material of the inside has been protected to the carbon bed that generates, thereby the carbon residue rate has been improved.

21-25 is the photocuring flame retardant coating of APP/NXSX/EA system, the result of burning under room temperature can be known to increase with the increase of NXSX content, and when APP content is 20%, NXSX content is 10%, the carbon residue rate can reach 43.5% at most, with the increase of NXSX content, muffle furnace carbon residue rate increases gradually, even surpass the carbon residue rate of burning under the normal temperature, this probably because active Zn and Sn have catalytic char formation effect to the burning of polymer, when the polymer degrades, can char rapidly, make carbon residue rate improve, and the coating is easily heated and softened under the high temperature, APP can promote the formation of carbon layer, nitrogen element can impel the coating inflation, the carbon layer that produces has protected the material of inside, thereby the carbon residue rate has been improved.

26-30 are the photocuring flame retardant coating of APP/HPNXSX/EA system, the result of burning under room temperature is known to increase with the increase of the carbon residue rate of HPNXSX content, and when the APP content is 20%, the HPNXSX content is 10%, the carbon residue rate can reach 44.1% at most, and the carbon residue rate in muffle furnace is 47.0%, compared with 21-25, it is known that organically modified HPNXSX can improve its flame retardant property, because 1% sodium stearate can make the particle size of NXSX fine, help to increase its contact area to EA, can promote the polymer to turn carbon more, thus improve the flame retardant property of the coating, make the carbon residue rate improve.

31-40 of a photocuring flame-retardant coating of an APP/NSiSCX/EA system and 21-30 of a photocuring flame-retardant coating of an APP/HPNSiSXX/EA system, wherein when the APP content is 20% and the NSiSXX content is 10%, the carbon residue rate can reach 45.2% at most, the carbon residue rate in a muffle furnace is 46.4% at most, and the HPNSiSXX content is 10% at most, and the carbon residue rate in the muffle furnace is 49.2%, so that the carbon residue rate can be improved by containing the HPNSiSXX, and the reasons are the same.

In conclusion, the organic modification is carried out by SiO₂The NXSX with a shell structure can improve the flame retardant property of the coating, in the presence of APP, the carbon residue rate in a muffle furnace is basically greater than that at room temperature, and the carbon residue rate at room temperature and that in the muffle furnace of HPNSiXSX are the highest, so that the flame retardant effects of the flame retardants prepared in the experiment are as follows from high to low: HPNSiXSX>NSiXSX>HPNXSX>NXSX。

2) Morphology analysis of carbon residue after coating combustion

The shape of carbon residue of the NXSX/EA system coating after being burnt at 100 ℃ and 500 ℃ shows that the expansion multiple of a zinc stannate coating at 500 ℃ is larger than that at 100 ℃, but the carbon residue at 500 ℃ is brittle and smooth, probably because the coating is easily softened by heat at high temperature, the NXSX is easily degraded to generate active Zn and Sn when being heated, and the active Zn and Sn have a catalytic carbonization effect on the burning of a polymer.

The morphology of carbon residue after combustion at 100 ℃ and 500 ℃ of the HPNXSX/EA system coating shows that the expansion factor of the system at 500 ℃ is higher than that at 100 ℃, and compared with the coating of the NXSX/EA system, the expansion factor of the HPNXSX at 500 ℃ is higher than that of the NXSX at 500 ℃, probably because the added sodium stearate is beneficial to forming a carbon layer, the carbon layer with larger expansion factor is formed nearby, and the improvement of the flame retardant property is promoted, and the particle size of the NXSX is thinned by 1 percent of the sodium stearate, so that the contact area of the sodium stearate to the EA is favorably increased, and the polymer is promoted to form carbon.

The appearances of carbon residues after the combustion of the NSiXSX/EA system coating at 100 ℃ and 500 ℃ and the appearances of carbon residues after the combustion of the HPNSiXSX/EA system coating at 100 ℃ and 500 ℃ are shown, and according to the comparison with the NXSX/EA system coating and the HPNXSX/EA system coating, SiO is found₂The NXSX system with a shell structure has an expansion coefficient which is increased by 42 times compared with the NXSX system, probably because of SiO₂The flame retardant can play a synergistic flame retardant role with NXSX, so that a carbon layer with better effect can be promoted in the combustion process of a system, and the carbon layer can cover the surface layer of a base material and can well prevent the spread of fire.

The appearance of the carbon residue after 100 ℃ and 500 ℃ combustion of the APP/EA system coating shows that when the content of the APP flame-retardant monomer is increased, the expansion multiple is increased and can reach 52 times at 500 ℃, probably because the coating is easily heated and softened at high temperature, and the gas source is decomposed to generate gas, so that the APP is decomposed to promote the generation of the carbon layer, and the nitrogen element promotes the expansion of the coating, thereby obtaining the carbon layer with higher expansion multiple.

The morphology of the carbon residue of the NXSX and APP synergistic flame retardant composite/EA coating after combustion at 100 ℃ and 500 ℃ shows that, compared with the morphology of the carbon residue of the uncoordinated APP, any system in the presence of APP, whether at 100 ℃ or at 500 DEG CThe expansion times are all improved and can reach 70 times at most. The reasons may be as follows: firstly, the coating is easy to be softened by heat at high temperature, the active Zn and Sn have catalytic carbonization effect on the combustion of the polymer, when the polymer is degraded, the carbon can be rapidly formed, meanwhile, the degraded carbon layer is also easy to be softened by heat, and in addition, the gas generated by the decomposition of a gas source can promote the carbon layer to be rapidly expanded to form a flame-retardant coating with a large volume multiple; secondly, the added sodium stearate is beneficial to forming a carbon layer, so that the carbon layer with larger expansion factor can be formed, and the improvement of the flame retardant property is promoted; III, SiO₂The flame retardant coating and NXSX can play a synergistic flame retardant role, so that a carbon layer with better effect can be promoted in the combustion process of a system, and the carbon layer is covered on the surface layer of a base material, and the spread of fire can be well prevented.

5. Thermogravimetric analysis

FIG. 23 is a thermogravimetric plot of NXSX/EA flame retardant coating, reflecting the mass of the coating as a function of temperature at a programmed temperature control. As can be seen from the figure, the thermal degradation of the system is divided into three stages, wherein the first stage is 0-380 ℃, the mass change of the coating in the first stage is very small, and the degradation rate of the coating is very low and is probably caused by the evaporation of a small amount of water contained in the coating; the second stage is 380-440 ℃, the degradation rate is high, and the coating is rapidly degraded to generate CO₂The quality of the system is rapidly reduced; the third stage is 440-600 ℃, and the degradation rate of the coating gradually slows down and finally tends to be flat. When the NXSX content is 10 wt%, the carbon residue rate can reach 30% at 500 ℃, so that the NXSX/EA system has good flame retardant effect and is similar to data measured in a muffle furnace (500 ℃). The temperature at which the coating starts to degrade is 350 ℃, which shows that the system has higher stability at low temperature; as the temperature increases, the NXSX/EA coating begins to degrade. The NXSX is easy to degrade to generate active Zn and Sn during heating, the active Zn and Sn have catalytic char formation effect on the combustion of the polymer, and when the polymer degrades, the active Zn and Sn can form char quickly, so that the flame retardant property of the polymer is improved.

FIG. 24 is a thermal diagram of an APP/EA flame retardant coating. As can be seen from the figure, the thermal degradation of the system is divided into three stages, the first stage is 0-330 ℃, the mass change of the coating in the first stage is small,the rate of degradation of the coating is low, probably due to evaporation of the small amount of water contained in itself; the second stage is 330-440 ℃, the degradation rate is high, and the coating is rapidly degraded to generate CO₂The quality of the system is rapidly reduced; the third stage is 440-660 ℃, and the degradation rate of the coating in the stage gradually becomes slow and finally tends to be gentle. The APP flame retardant has an initial degradation temperature of 310 ℃, and when the content of ammonium polyphosphate is 20 wt%, the final weight percentage at 500 ℃ can reach 42% at most by thermal degradation, and the residue residual quantity of the material at high temperature is gradually reduced along with the increase of the temperature in the process of thermal oxidation degradation. During the temperature rise, the P, N-containing coating degrades to generate a polyphosphoric acid structure which can catalyze the dehydration and carbonization of carboxylic ester to form a stable carbon layer structure, and as the temperature rises further, the residue is gradually oxidized to only leave a few amorphous carbon and inorganic materials which are main protective layers of the bottom substrate in the later period of combustion.

FIG. 25 is a thermogravimetric graph of an APP/NSiXSX/EA flame retardant coating, and it can be seen from the graph that the thermal degradation of the system is divided into three stages, the first stage is 0-350 ℃, the mass change of the coating in the stage is small, the rate of the coating degradation is low, and the coating degradation is probably caused by evaporation of a small amount of water contained in the coating; the second stage is 350-430 ℃, the degradation rate is high, and the coating is rapidly degraded to generate CO₂The quality of the system is rapidly reduced; the third stage is 430-650 ℃, and the degradation rate of the coating in the stage gradually becomes slow and finally becomes gentle. The reason is that: firstly, the active Zn and Sn can catalyze the polymer to form carbon, and when the polymer is degraded, the carbon can be formed rapidly, so that the flame retardant property of the polymer is improved; secondly, Si-O-Si bonds form a net structure in the combustion process, and the net structure is covered on the surface of the carbon layer to play a role in protection and prevent the coating from being further oxidized; thirdly, siloxane can generate Si-C bonds during combustion to isolate oxygen from the coating, so that the flame retardant effect is achieved; fourthly, the gas source promotes the system to foam rapidly into an expanded carbon layer after burning, and the expanded carbon layer covers the surface layer of the carbon layer to play a role in protecting the flame-retardant matrix.

FIG. 26 is a thermal diagram of the APP/HPNSiSCX/EA flame retardant coating, from which it can be seen that the bodyThe thermal degradation of the system is divided into three stages, wherein the first stage is 0-350 ℃, the mass change of the coating in the stage is very small, the degradation rate of the coating is very low, and the degradation rate is probably caused by evaporation of a small amount of water contained in the coating; the second stage is 350-480 ℃, the degradation rate is high, and the coating is rapidly degraded to generate CO₂The quality of the system is rapidly reduced; the third stage is 480-700 ℃, and the degradation rate of the coating in the stage gradually becomes slow and finally becomes gentle. As can be seen from FIG. 26, when the APP content is 200 wt% and the HPNSiXSX content is 10 wt%, the final weight percentage at 500 ℃ can reach 50% at most by thermal degradation, and the char yield at 700 ℃ is 4.2% by thermal degradation, which indicates that the system has higher stability at high temperature. Comparison with fig. 25 shows that sodium stearate can further improve the flame retardant performance, probably because 1% of sodium stearate can make the NXSX particle size become fine, which is beneficial to increasing the contact area of the NXSX particle size to EA, and can promote polymer charring, thereby improving the flame retardant performance of the coating and ensuring better thermal stability.

6. Conclusion

(1) With SnC1₄·5H₂O and ZnC1₂·3H₂O is used as raw material to prepare nano zinc stannate (NXSX), organic nano zinc stannate (HPNXSX), nano zinc stannate capsule (NSiSXX) and organic nano zinc stannate capsule (HPNSiSXX).

(2) The carbon residue rate of the APP/HPNSiSXX/EA coating is the highest, the carbon residue rate reaches 46.2% at 100 ℃, and the carbon residue rate reaches 48.2% in a muffle furnace (500 ℃). The research finds that the sodium stearate and the nano SiO₂The carbon residue rate of the NXSX/EA coating can be improved.

(3) In the APP/HPNSiXSX/EA system, when the APP accounts for 20 percent and the HPNSiXSX accounts for 10 percent, the LOI value can reach 35 at most, the UL-94 can reach V-0, and the hardness is 6H. The combustion carbon residue rate at room temperature is 48.2%, the carbon residue rate at 500 ℃ in a muffle furnace is 49.2%, and the stability of the coating is highest.

(4) The APP/HPNSiXSX/EA coating is added, so that the coating is easy to degrade in a low-temperature area, a good expanded carbon layer is formed, and the flame retardant property of the coating is improved.

(5) The NXSX has great influence on the light transmittance of the system, when the content of the NXSX is 3 percent, the light transmittance is only 70 percent, and the content is dependent on NAn increase in XSX content decreases the light transmission and the organic modification decreases the light transmission of the NXSX/coating, but with SiO₂The nuclear structure has great improvement effect on the NXSX/coating light transmittance.

(6) The expansion multiple of the NXSX/EA coating at 500 ℃ can reach 30 times, and the expansion multiple is improved after the coating is organically modified, which shows that the expansion multiple of the sodium stearate can be improved, and the SiO₂The core-shell structure of (2) can increase the expansion times, which can reach 42 times at most. At an APP content of 10 wt% and a NSiXSX of 3 wt%, the expansion times reach a maximum of 70 times.

The above description is only a preferred embodiment of the present invention, and therefore should not be taken as limiting the scope of the invention, which is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a nano zinc stannate flame retardant with a core-shell structure is characterized by comprising the following steps: the method comprises the following steps:

1) mixing tin chloride and zinc chloride according to a molar ratio of 0.8-1.2: dissolving the mixture in water in a ratio of 0.8-1.2, dropwise adding a proper amount of acid to prevent tin chloride from hydrolyzing, and adding sodium stearate into a system in which tin chloride and zinc chloride are dissolved in water, wherein the mass of the sodium stearate is 0.5-1.5% of the total mass of the tin chloride and the zinc chloride; uniformly mixing, adjusting the pH value to 7.8-9.2, crystallizing at room temperature for 5-7 h, filtering, washing with water at 65-75 ℃ for several times, and drying at 65-75 ℃ to obtain nano zinc stannate;

2) uniformly mixing nano zinc stannate with absolute ethyl alcohol, water and tween-80, and dropwise adding tetraethoxysilane, wherein the formula ratio of the nano zinc stannate to the absolute ethyl alcohol to the water to the tween-80 to the tetraethoxysilane is 9-11 g: 78-82 g: 9-11 mL: 0.08-0.12 g: 6.5-7.5 g, then adjusting the pH value to 7.8-8.2, keeping the temperature at 65-75 ℃, stirring and reacting for 2-4 h, cooling, filtering, washing and drying to obtain the nano zinc stannate flame retardant with the core-shell structure.

2. The nano zinc stannate flame retardant with the core-shell structure prepared by the preparation method of claim 1.

3. The preparation method of the epoxy acrylate intumescent flame retardant coating is characterized by comprising the following steps of: the method comprises the following steps: sequentially and one by one adding acrylic acid, APP, the nano zinc stannate flame retardant with the core-shell structure and the epoxy acrylate into acrylamide, wherein the nano zinc stannate flame retardant with the core-shell structure and the epoxy acrylate are prepared by the preparation method according to claim 1, and the mass ratio of the acrylic acid to the acrylamide to the APP to the nano zinc stannate flame retardant with the core-shell structure to the epoxy acrylate is 1.8-2.2: 1.4-1.6: 0.8-2.2: 0.2-1.2: 3.2-5.5, and uniformly mixing and eliminating bubbles when adding the epoxy acrylate intumescent flame retardant coating every time to obtain the epoxy acrylate intumescent flame retardant coating.

4. The method for preparing the epoxy acrylate intumescent flame retardant coating according to claim 3, characterized in that: the mass ratio of the acrylamide, the acrylic acid, the APP, the nano zinc stannate flame retardant with the core-shell structure and the epoxy acrylate is 2: 1.5: 2: 1: 3.5.

5. the method for preparing the epoxy acrylate intumescent flame retardant coating according to claim 3, characterized in that: further comprising: and finally adding an initiator accounting for 2-4% of the total mass of the system.

6. The method for preparing the epoxy acrylate intumescent flame retardant coating according to claim 5, characterized in that: the initiator is a photoinitiator 1173.

7. An epoxy acrylate intumescent flame retardant coating prepared according to the preparation method of any one of claims 3 to 6.