阅读说明：本技术 一种改性β-环糊精-DOPO复合材料及其制备方法 (Modified beta-cyclodextrin-DOPO composite material and preparation method thereof ) 是由 陈星佑 孙铜 徐鹏举 肖玉 袁园 于 2021-09-28 设计创作，主要内容包括：本发明公开了一种改性β-环糊精-DOPO复合材料及其制备方法,制备方法包括以下步骤：将无水乙醇和去离子水混合后,加入β-环糊精,再加入硅烷偶联剂反应,产物经洗涤、过滤、烘干后,得到改性β-环糊精；然后将其溶解于去离子水中,再滴入用THF溶解的DOPO进行反应,得到的产物经旋蒸、抽滤、提纯、干燥处理后,制得。本发明利用β-环糊精空腔结构包合DOPO,解决了DOPO在单独添加到环氧树脂中时容易迁移到表面的问题,同时对β-环糊精进行改性增加了其与环氧树脂的相容性,还利用DOPO和β-环糊精具有良好阻燃性能的特点,构筑了一种具有高效阻燃性能的无卤绿色阻燃材料。(The invention discloses a modified beta-cyclodextrin-DOPO composite material and a preparation method thereof, wherein the preparation method comprises the following steps: mixing absolute ethyl alcohol and deionized water, adding beta-cyclodextrin, adding a silane coupling agent for reaction, and washing, filtering and drying a product to obtain modified beta-cyclodextrin; then dissolving the product in deionized water, dripping DOPO dissolved in THF for reaction, and performing rotary evaporation, suction filtration, purification and drying on the obtained product to obtain the product. The invention uses the cavity structure of the beta-cyclodextrin to include DOPO, solves the problem that the DOPO is easy to migrate to the surface when being added into the epoxy resin independently, modifies the beta-cyclodextrin to increase the compatibility of the beta-cyclodextrin and the epoxy resin, and uses the characteristic that the DOPO and the beta-cyclodextrin have good flame retardant property to construct the halogen-free green flame retardant material with high-efficiency flame retardant property.)

1. A preparation method of a modified beta-cyclodextrin-DOPO composite material is characterized by comprising the following steps:

(1) uniformly mixing absolute ethyl alcohol and deionized water, then adding beta-cyclodextrin, and stirring until the beta-cyclodextrin is uniformly dispersed;

(2) adding a silane coupling agent into the product obtained in the step (1), and reacting for 5-8h at 28-32 ℃;

(3) washing the product obtained in the step (2) with absolute ethyl alcohol, filtering, and drying at 80-100 ℃ to constant weight to obtain modified beta-cyclodextrin;

(4) dissolving the modified beta-cyclodextrin obtained in the step (3) in deionized water, slowly dripping DOPO dissolved in THF, and reacting at 40-60 ℃ for 5-8 h;

(5) and (4) standing the reaction liquid obtained in the step (4) for 10-15h, and then performing rotary evaporation, suction filtration, purification and drying treatment to obtain the modified beta-cyclodextrin-DOPO composite material.

2. The preparation method of the modified beta-cyclodextrin-DOPO composite material according to claim 1, wherein the mass of the absolute ethyl alcohol in the step (1) is 20 to 25 times that of the beta-cyclodextrin, and the mass of the deionized water is 2 to 3 times that of the beta-cyclodextrin.

3. The method for preparing a modified β -cyclodextrin-DOPO composite material according to claim 1, wherein the amount of the silane coupling agent in the step (2) is 2.5 to 80% by mass based on the amount of β -cyclodextrin.

4. The method for preparing a modified β -cyclodextrin-DOPO composite material according to claim 1, wherein the silane coupling agent in the step (2) is KH 560.

5. The method for preparing a modified beta-cyclodextrin-DOPO composite material according to claim 1, wherein the concentration of the modified beta-cyclodextrin in the deionized water in the step (4) is 45 to 60 mg/mL.

6. The method for preparing a modified β -cyclodextrin-DOPO composite material according to claim 1, wherein the DOPO dissolved in THF in the step (4) has a DOPO concentration of 20 to 30 mg/mL.

7. The method for preparing a modified β -cyclodextrin-DOPO composite material according to claim 1, wherein the mass of DOPO in the step (4) is 7 to 9% of the mass of the modified β -cyclodextrin.

8. The modified beta-cyclodextrin-DOPO composite material prepared by the method for preparing the modified beta-cyclodextrin-DOPO composite material as claimed in any one of claims 1 to 7.

9. Use of a modified β -cyclodextrin-DOPO composite according to claim 8 for flame retardancy.

Technical Field

The invention relates to the technical field of preparation of halogen-free flame retardant materials, and particularly relates to a modified beta-cyclodextrin-DOPO composite material and a preparation method thereof.

Background

Epoxy resin is used as a general thermosetting resin, and is widely used in various fields of national economy (coatings, adhesives, civil engineering materials, electronic and electrical materials, engineering plastics and composite materials) due to excellent comprehensive performance. However, epoxy resin is a flammable material, and has a limiting oxygen index of only about 19.5%, and when a fire occurs, the epoxy resin can be continuously burned even if it leaves the fire source. Meanwhile, the combustible fuel generates molten drops and a large amount of thick smoke in the combustion process, and the drops can continuously ignite surrounding combustible substances to cause the increase of the fire area. Meanwhile, dense smoke is one of the adverse factors of people escaping from fire and fire fighting and rescue, and brings great potential safety hazards to human production, life and environment. Therefore, in order to reduce or even eliminate the potential safety hazard of the epoxy resin in practical use and widen the market demand and application range of the epoxy resin, the flame retardant modification of the epoxy resin to improve the flame retardant property of the epoxy resin has important scientific research and practical significance.

Adding a phosphorus flame retardant DOPO into epoxy resin is an effective method for improving the flame retardant property of the epoxy resin, at present, the introduction of DOPO groups into the epoxy resin mainly adopts the following approaches, but each approach faces certain challenges, firstly, the flame retardant is easy to migrate through physical blending, and the flame retardant efficiency and the mechanical efficiency are reduced; secondly, the thermal property of the cured product formed in the mode is reduced through chemical bonding; thirdly, the application of the phosphorus flame retardant DOPO in the flame retardant field is limited by the molecular design, but the conditions of the molecular design are harsh and the economic benefit is low.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide a modified beta-cyclodextrin-DOPO composite material and a preparation method thereof, so as to solve the problem that the application of DOPO is limited when DOPO is added into epoxy resin in the prior art.

The technical scheme for solving the technical problems is as follows: the preparation method of the modified beta-cyclodextrin-DOPO composite material comprises the following steps:

(1) mixing anhydrous ethanol and deionized water, adding beta-cyclodextrin, and stirring to disperse uniformly;

(2) adding a silane coupling agent into the product obtained in the step (1), and reacting for 5-8h at 28-32 ℃;

(3) washing the product obtained in the step (2) with absolute ethyl alcohol, filtering, and drying at 80-100 ℃ to constant weight to obtain modified beta-cyclodextrin;

(4) dissolving the modified beta-cyclodextrin obtained in the step (3) in deionized water, slowly dripping DOPO dissolved in THF, and reacting at 40-60 ℃ for 5-8 h;

(5) and (4) standing the reaction liquid obtained in the step (4) for 10-15h, and then performing rotary evaporation, suction filtration, purification and drying treatment to obtain the modified beta-cyclodextrin-DOPO composite material.

The invention has the beneficial effects that: the beta-cyclodextrin molecule has a special cavity structure and is in a thick-wall truncated cone structure, the inner cavity has high hydrophobicity, the outer part consists of hydroxyl, and the beta-cyclodextrin molecule has high hydrophilicity. Meanwhile, the beta-cyclodextrin has good thermal stability and is widely applied to the field of flame retardance, the DOPO is included by fully utilizing the cavity structure of the beta-cyclodextrin, the DOPO is prevented from migrating in the processing process of a high polymer material, and the flame retardance efficiency is improved; however, because the compatibility of the beta-cyclodextrin and the epoxy resin is poor, the silane coupling agent is utilized to modify the beta-cyclodextrin, so that the compatibility of the beta-cyclodextrin and the epoxy resin is improved. The invention effectively utilizes the characteristics of good flame retardant property of DOPO and beta-cyclodextrin, prepares the halogen-free green flame retardant with high-efficiency flame retardant property by a inclusion technology, and the flame retardant can be successfully added into epoxy resin as a filler to form flame retardant epoxy resin.

On the basis of the technical scheme, the invention can be further improved as follows:

further, the mass of the absolute ethyl alcohol in the step (1) is 20-25 times of that of the beta-cyclodextrin, and the mass of the deionized water is 2-3 times of that of the beta-cyclodextrin.

Further, the mass of the silane coupling agent in the step (2) is 2.5-80% of that of the beta-cyclodextrin.

Further, the silane coupling agent in the step (2) is KH 560.

The beneficial effect of adopting the further technical scheme is as follows:

the methoxy group of the silane coupling agent gamma-glycidoxypropyltrimethoxysilane (KH560) is easy to hydrolyze to generate a large amount of Si-OH structure RSi (OH)₃The structure has strong reactivity, can form chemical bonds and hydrogen bonds with hydroxyl groups on the beta-cyclodextrin to realize the modification of the beta-cyclodextrin, simultaneously has better compatibility of a silane coupling agent KH560 and epoxy resin, improves the hydrophilic and oleophobic properties of the beta-cyclodextrin by utilizing the coupling agent, and improves the mechanical properties of the epoxy resin because the modified beta-cyclodextrin has better dispersibility and compatibility in the epoxy resin.

Further, the concentration of the modified beta-cyclodextrin in the step (4) in the deionized water is 45-60 mg/mL.

Further, in the DOPO solution dissolved in THF in the step (4), the concentration of DOPO is 20-30 mg/mL.

Further, the mass of DOPO in the step (4) is 7-9% of the mass of the modified beta-cyclodextrin.

The invention also provides a modified beta-cyclodextrin-DOPO composite material prepared by the preparation method of the modified beta-cyclodextrin-DOPO composite material.

The invention also provides application of the modified beta-cyclodextrin-DOPO composite material in flame retardance.

The invention has the following beneficial effects: the beta-cyclodextrin is modified by utilizing a silane coupling agent KH560, the modified beta-cyclodextrin and DOPO are subjected to inclusion technology to prepare a modified beta-cyclodextrin-DOPO composite material, and the composite material has triple functions: the DOPO is included in the beta-cyclodextrin, so that the migration of a flame retardant in the processing process of a high polymer material is avoided, and the flame retardant efficiency is improved; beta-cyclodextrin not only has inclusion effect, but also can be used as a carbon source of a flame retardant system due to the fact that the molecular structure of beta-cyclodextrin contains a large number of hydroxyl groups, and the flame retardant property of the epoxy resin is improved; and thirdly, hydroxyl in the beta-cyclodextrin can also react with an epoxy group in the epoxy resin to form the intrinsic flame-retardant epoxy resin, so that the flame retardant property of the intrinsic flame-retardant epoxy resin is improved.

Drawings

FIG. 1 is an infrared spectrum of a silane coupling agent KH560, a beta-cyclodextrin and a modified beta-cyclodextrin;

FIG. 2 is a partial view of an infrared spectrum of a silane coupling agent KH560, a beta-cyclodextrin and a modified beta-cyclodextrin;

FIG. 3 is a thermogram of DOPO, modified beta-cyclodextrin and beta-cyclodextrin-DOPO composite;

FIG. 4 is a front view of the dispersion effect of modified beta-cyclodextrin in epoxy resin;

FIG. 5 is a reverse view of the dispersion effect of modified beta-cyclodextrin and epoxy resin;

FIG. 6 is a HRR chart of cured epoxy resins with different additives.

Detailed Description

The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Example 1:

a preparation method of a modified beta-cyclodextrin-DOPO composite material comprises the following steps:

(1) sequentially adding 90g of absolute ethyl alcohol and 10g of deionized water into a round-bottom flask, stirring for 5min, slowly adding 4g of beta-cyclodextrin into the flask, and stirring until the beta-cyclodextrin is uniformly dispersed;

(2) adding 0.4g of silane coupling agent KH560 into the product obtained in the step (1), and reacting for 6.5h at 30 ℃;

(3) washing the product obtained in the step (2) with absolute ethyl alcohol for 5 times, filtering, and drying at 90 ℃ to constant weight to obtain modified beta-cyclodextrin;

(4) dissolving the modified beta-cyclodextrin obtained in the step (3) in deionized water at 50 ℃, then slowly dripping DOPO dissolved in THF, and reacting for 6.5h at 50 ℃;

wherein the concentration of the modified beta-cyclodextrin in deionized water is 52.7mg/mL, the concentration of DOPO in THF is 25mg/mL, and the mass of the DOPO is 8.3% of that of the modified beta-cyclodextrin;

(5) and (4) standing the reaction liquid obtained in the step (4) for 12 hours, and then performing rotary evaporation, suction filtration, purification and drying treatment to obtain the modified beta-cyclodextrin-DOPO composite material.

Example 2:

a preparation method of a modified beta-cyclodextrin-DOPO composite material comprises the following steps:

(1) sequentially adding 80g of absolute ethyl alcohol and 10g of deionized water into a round-bottom flask, stirring for 4min, slowly adding 4g of beta-cyclodextrin into the flask, and stirring until the beta-cyclodextrin is uniformly dispersed;

(2) adding 0.1g of silane coupling agent KH560 into the product obtained in the step (1), and reacting for 8h at 28 ℃;

(3) washing the product obtained in the step (2) with absolute ethyl alcohol for 5 times, filtering, and drying at 80 ℃ to constant weight to obtain modified beta-cyclodextrin;

(4) dissolving the modified beta-cyclodextrin obtained in the step (3) in deionized water at 40 ℃, then slowly dripping DOPO dissolved in THF, and reacting for 8h at 40 ℃;

wherein the concentration of the modified beta-cyclodextrin in deionized water is 45mg/mL, the concentration of DOPO in THF is 20mg/mL, and the mass of the DOPO is 7% of that of the modified beta-cyclodextrin;

(5) and (4) standing the reaction liquid obtained in the step (4) for 10 hours, and then performing rotary evaporation, suction filtration, purification and drying treatment to obtain the modified beta-cyclodextrin-DOPO composite material.

Example 3:

a preparation method of a modified beta-cyclodextrin-DOPO composite material comprises the following steps:

(1) sequentially adding 100g of absolute ethyl alcohol and 12g of deionized water into a round-bottom flask, stirring for 8min, slowly adding 4g of beta-cyclodextrin into the flask, and stirring until the beta-cyclodextrin is uniformly dispersed;

(2) adding 3.2g of silane coupling agent KH560 into the product obtained in the step (1), and reacting for 5h at 32 ℃;

(3) washing the product obtained in the step (2) with absolute ethyl alcohol for 5 times, filtering, and drying at 100 ℃ to constant weight to obtain modified beta-cyclodextrin;

(4) dissolving the modified beta-cyclodextrin obtained in the step (3) in deionized water at 60 ℃, then slowly dripping DOPO dissolved in THF, and reacting for 5h at 60 ℃;

wherein the concentration of the modified beta-cyclodextrin in deionized water is 60mg/mL, the concentration of DOPO in THF is 30mg/mL, and the mass of the DOPO is 9% of that of the modified beta-cyclodextrin;

(5) and (4) standing the reaction liquid obtained in the step (4) for 15 hours, and then performing rotary evaporation, suction filtration, purification and drying treatment to obtain the modified beta-cyclodextrin-DOPO composite material.

And (4) detecting a result:

the modified β -cyclodextrin-DOPO composite materials obtained in examples 1 to 3 were tested for their substantially consistent performance parameters, and the modified β -cyclodextrin-DOPO composite material obtained in example 1 is specifically described below:

1. modification of modified beta-cyclodextrin

The silane coupling agent KH560, the beta-cyclodextrin and the modified beta-cyclodextrin prepared in example 1 were respectively analyzed on an infrared spectrometer to obtain infrared absorption spectrograms, and the results are shown in FIGS. 1 and 2, since beta-cyclodextrin (beta-CD) contains a large amount of methyl and methylene groups, the concentration of the beta-cyclodextrin (beta-CD) can be 3000cm^-1Corresponding absorption peaks appear around, and the silane coupling agent KH560 contains Si-O-Si bonds and can reach 1000cm^-1The absorption peaks appeared at the left and right sides, and as can be seen from FIGS. 1 and 2, 2944cm^-1And 2845cm^-1Respectively representing the stretching vibration peak of methyl and methylene, 1192cm^-1And 1087cm^-1Is a stretching vibration peak and a weak absorption peak of Si-O-Si, and the modified beta-cyclodextrin (m-beta-CD) map has 1082cm in comparison with the beta-cyclodextrin (beta-CD) map^-1And 1188cm^-1Two peaks, indicating that the silane coupling agent KH560 was successfully grafted on beta-cyclodextrin (beta-CD).

2. Inclusion of modified beta-cyclodextrin with DOPO

DSC can be used for verifying whether the inclusion of DOPO and modified beta-cyclodextrin (m-beta-CD) is realized, if the inclusion is not successful or is not completely included, a melting peak of DOPO appears on the curve of IC. The DSC of the modified β -cyclodextrin-DOPO composite material obtained in example 1 was verified, and the results are shown in fig. 3, and it can be seen from fig. 3 that the DOPO-containing composite material of modified β -cyclodextrin does not have a peak in the range of 20 to 160 ℃, indicating that DOPO is completely contained in modified β -cyclodextrin (m- β -CD); since the modified beta-cyclodextrin (m-beta-CD) is stable below 270 ℃, no defined melting peak occurs within the test temperature, in which temperature range DOPO exhibits a strong melting peak at 120.8 ℃.

3. Compatibility of modified beta-cyclodextrin with epoxy resins

4g of the modified beta-cyclodextrin obtained in example 1 and 40g of E-44 epoxy resin are taken, mixed uniformly in a water bath at 70 ℃, 4.64g of m-phenylenediamine (curing agent) is added, the mixture is poured into a mold after being mixed uniformly, the mold is placed in a vacuum oven, the vacuum oven is vacuumized at 70 ℃ until bubbles disappear, then the mixture is cured at 70 ℃ for 2h under the normal pressure condition, then the mixture is cured at 80 ℃ for 1h, and finally the mixture is cured at 150 ℃ for 4 h. The appearance of the final cured product is shown in fig. 4 and fig. 5, and as can be seen from fig. 4 and fig. 5, the transparency of the pure epoxy resin cured product is good, the cured product prepared by adding unmodified beta-cyclodextrin into epoxy resin (EP) is obviously layered, a large amount of beta-cyclodextrin is deposited at the bottom, and the cured product prepared by adding modified beta-cyclodextrin into epoxy resin (EP) is not layered, which indicates that the modified beta-cyclodextrin prepared by the invention is well dispersed in epoxy resin (EP).

4. Improvement of flame retardant property of modified beta-cyclodextrin-DOPO composite material on epoxy resin

The modified beta-cyclodextrin-DOPO composite material prepared in example 1 and DOPO/m-beta-CD (physical blend of DOPO and modified beta-cyclodextrin) were investigated for the improvement of flame retardancy of EP cured products, and fig. 6 is an HRR graph of cured products obtained by two addition methods. As can be seen from FIG. 6, the PHRR of the EP composite material obtained by physical blending is 236w/g, the EP composite material added with the flame retardant prepared by the inclusion reaction has a lower PHRR value, and the PHRR value is 216w/g, which shows that the flame retardant prepared by the inclusion reaction can improve the flame retardant property of the EP composite material.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.