Bio-based DOPO derivative flame retardant as well as preparation method and application thereof

Abstract

The invention discloses a bio-based DOPO (9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) derivative flame retardant as well as a preparation method and application thereof. The preparation method comprises the following specific steps: S1, weighing DOPO in a container, adding a solvent, and uniformly stirring and mixing; s2, adding curcumin and triethylamine into a container, and uniformly stirring in a stirrer; s3, dropwise adding carbon tetrachloride into the container while stirring, and controlling the temperature within 10 DEG C in the gradual adding process; s4, reacting at room temperature for 8-12 hours; s5, sequentially extracting and washing the reacted solution with hydrochloric acid, sodium bicarbonate and deionized water to obtain a lower-layer viscous liquid; and S6, carrying out reduced pressure distillation to obtain a vacuum dried product DOPO-CUR. According to the DOPO-CUR disclosed by the invention, the epoxy resin can reach LOI32.6% and UL94V-0 level under the condition that the phosphorus content of the DOPO-CUR in the epoxy resin only reaches 0.41%, and meanwhile, the epoxy resin can still keep good mechanical properties.

Description

Technical Field

[0001] The invention relates to a bio-based DOPO derivative flame retardant and a preparation method and application thereof, belonging to the technical field of flame retardants. Background Art

[0002] As a kind of thermosetting plastic, epoxy resin has many advantages and is widely used, but it is flammable, so flame retardants must be used to retard epoxy resin.

[0003] Halogen flame retardant is the first flame retardant to be studied. It can also exert high flame retardancy without changing the various properties of the resin matrix. However, the large amount of toxic and harmful gases and smoke released during its combustion process are obvious to all, which is harmful to people's health and nature. Therefore, it is necessary to develop various green and non-toxic environmentally friendly flame retardants to replace traditional halogen flame retardants. Phosphorus-containing flame retardants are the most popular type of flame retardants. However, although inorganic phosphorus flame retardants can provide flame retardancy in epoxy resin, due to poor compatibility with epoxy resin, the flame retardant efficiency is reduced and the mechanical properties are greatly reduced. This is unacceptable in actual life and production. Therefore, the organic phosphorus flame retardant DOPO has attracted people's attention. However, a single DOPO flame retardant system often requires the addition of a large amount of flame retardant, and the large amount of DOPO added will affect the mechanical strength and other properties of the material. With the increasing requirements for the balance between the flame retardant properties and the overall performance of epoxy resin, the construction of a composite system is more conducive to maintaining the overall performance indicators of the material. Due to the structure and composition of the bio-based modified flame retardant itself, it has the characteristic of rapid carbonization, which can greatly improve the anti-combustion performance of epoxy resin. Therefore, bio-based derived flame retardants have attracted much attention from researchers. However, bio-based flame retardants also face many problems, such as the complex preparation process, the large amount required to be added to achieve the desired effect, and the low thermal stability. Therefore, there is still a challenging problem of how to effectively improve the fire retardancy of epoxy resin while adding a low amount.

[0004] Therefore, it is necessary to design a new bio-based flame retardant that can maintain high flame retardancy and mechanical properties of epoxy resin at a lower addition amount. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a bio-based DOPO derivative flame retardant and a preparation method and application thereof, so as to solve the technical problems of large amount of flame retardant addition and complex synthesis process in the process of preparing flame-retardant epoxy resin proposed in the background technology, and the technical problems of poor mechanical properties and poor flame retardant efficiency of the prepared flame-retardant epoxy resin.

[0006] In order to solve the above technical problems, the present invention provides a bio-based DOPO derivative flame retardant, the structural formula of which is Abbreviated as DOPO-CUR.

[0007] The preparation method of a bio-based DOPO derivative flame retardant according to the present invention comprises the following specific steps:

[0008] S1. Weigh DOPO into a container, add solvent, and stir to mix evenly;

[0009] S2, adding curcumin and triethylamine into a container, and stirring evenly under a stirrer;

[0010] S3, adding carbon tetrachloride dropwise into the container under stirring, and controlling the temperature within 10°C during the addition process;

[0011] S4, react at room temperature for 8 to 12 hours;

[0012] S5, extracting and washing the reaction solution with hydrochloric acid, sodium bicarbonate, and deionized water in sequence to obtain a lower layer of viscous liquid;

[0013] S6. The separated lower layer of viscous liquid is subjected to reduced pressure distillation to remove the solvent in the reaction, and the product DOPO-CUR is obtained by vacuum drying after precipitation.

[0014] Preferably, in S2, the molar ratio of curcumin to DOPO is 1:1.8-2.2, and the molar ratio of triethylamine to DOPO is 1:0.8-1.2; in S3, the molar ratio of carbon tetrachloride to DOPO is 1:0.8-1.2.

[0015] Preferably, the molar ratio of curcumin, DOPO, carbon tetrachloride and triethylamine is 1:2:2:2.

[0016] Preferably, the solvent is one or more of dichloromethane, ethyl acetate, acetonitrile, tetrahydrofuran and chloroform.

[0017] Preferably, the mass of the solvent used is 3 to 8 times the mass of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0018] Preferably, in S5, the concentration of hydrochloric acid used for extraction and washing is 0.05-0.15 mol / L, and the concentration of sodium bicarbonate used for extraction and washing is 0.05-0.15 mol / L; the extraction and washing are performed 2-3 times with hydrochloric acid, sodium bicarbonate and deionized water respectively.

[0019] Preferably, the stirrer is a heat-collecting magnetic stirrer; and in S3, a constant pressure dropping funnel is used for dropwise addition.

[0020] The present invention also provides an application of a bio-based DOPO derivative flame retardant, wherein the bio-based DOPO derivative flame retardant DOPO-CUR is used to prepare a flame-retardant epoxy resin; wherein the bio-based DOPO derivative flame retardant DOPO-CUR is the bio-based DOPO derivative flame retardant DOPO-CUR described above; or, the bio-based DOPO derivative flame retardant DOPO-CUR is prepared by the preparation method described above.

[0021] Preferably, the epoxy resin and DOPO-CUR are stirred at 120-150° C. to obtain a uniform solution, 4,4'-diaminodiphenylmethane is added and stirred until transparent, poured into a mold, first vacuum dried at 90-110° C. for 2-3 h, and then vacuum dried at 140-160° C. for 3-5 h, to obtain an epoxy resin containing DOPO-CUR.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention synthesizes curcumin and DOPO to prepare a bio-based DOPO derivative flame retardant DOPO-CUR, which solves the technical problems of poor flame retardant performance, high addition amount and complex synthesis process of existing flame retardants. The flame retardant of the present invention has good flame retardant effect, low smoke, non-toxicity and high thermal stability.

[0024] 2. The flame retardant of the present invention has good compatibility with epoxy resin and can maintain high chemical and thermal stability of epoxy resin.

[0025] 3. The present invention combines DOPO with curcumin for reaction. The molecular structure contains phosphorus and carbon elements for synergistic flame retardancy. Phosphorus and carbon elements can promote the formation of a carbon layer. PO and P=O of DOPO have a gas phase flame retardant effect. The synergistic effect overcomes the deficiency of a single flame retardant element, improves heat resistance and high-temperature carbonization rate, and can make the epoxy resin reach LOI32.6% and UL94V-0 level when the phosphorus content is only 0.41%. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0027] Figure 1 is a FTIR spectrum of a bio-based DOPO derivative flame retardant of the present invention;

[0028] Figure 2 The invention discloses a bio-based DOPO derivative flame retardant. 31 P NMR spectrum;

[0029] Figure 3 The invention discloses a bio-based DOPO derivative flame retardant. 1 HNMR spectrum;

[0030] Figure 4 It is a comparison chart of the total smoke generation of the epoxy resin containing 5% DOPO-CUR and the pure epoxy resin of the present invention;

[0031] Figure 5 It is a comparison chart of the total heat release of the epoxy resin containing 5% DOPO-CUR and the pure epoxy resin of the present invention;

[0032] Figure 6 It is a comparison chart of the heat release rate of the epoxy resin containing 5% DOPO-CUR of the present invention and that of pure epoxy resin. DETAILED DESCRIPTION

[0033] The present invention will be described in detail below in conjunction with the embodiments and drawings. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0034] Example 1

[0035] Take 10.16g of DOPO and dissolve it in a 250ml three-necked flask filled with dichloromethane, add a magnet to the three-necked flask, place the three-necked flask in a heat-collecting magnetic stirrer, add ice cubes, control the temperature within 10°C, and stir for 10 minutes; weigh 6.63g of curcumin and 5.87g of triethylamine, dissolve them in the above three-necked flask, weigh 8.92g of carbon tetrachloride and add it dropwise to the three-necked flask through a constant pressure dropping funnel, and control the temperature within 10°C. After the addition was completed, the temperature of the heat-collecting magnetic stirrer was raised to room temperature, and the reaction time was 12 hours; the product solution after the reaction was loaded into a separatory funnel, and extracted and washed with 0.1 mol / L dilute hydrochloric acid, 0.1 mol / L sodium bicarbonate, and deionized water, respectively. After extraction and washing, the lower layer of viscous liquid obtained by separation was distilled under reduced pressure to recover the dichloromethane in the reaction, the reaction was stopped, and the reaction solution was vacuum dried to obtain the target compound DOPO-CUR with a yield of 84.5%.

[0036] Infrared spectrum analysis results of compound DOPO-CUR: FT-IR (KBr), v / cm -1 : 1595, 1506 and 1476cm -1 The absorption peak is attributed to the bending vibration of the benzene ring. -1 A new characteristic absorption peak attributed to the POC bond also appears at Figure 1 The change of characteristic absorption peaks in the FTIR spectrum shown preliminarily confirmed the successful synthesis of the target product.

[0037] like Figure 2 As shown in the DOPO-CUR 31 In the P NMR spectrum, a chemical shift peak at 6.92 ppm can be observed, indicating that a new chemical environment of P element appears in the synthesized DOPO-CUR. The NMR spectrum further confirms that the product synthesized in this experiment is consistent with the target product.

[0038] like Figure 3 As shown in the DOPO-CUR 1 In the HNMR spectrum, it can be observed that there are 30 H atoms in the region of the peak where the H element is located, which is the same as the number of hydrogen atoms contained in the DOPO-CUR compound, proving that the synthesized product is consistent with the target product.

[0039] This article also provides an application of a bio-based DOPO derivative flame retardant, wherein the bio-based DOPO derivative flame retardant DOPO-CUR is used to prepare a flame-retardant epoxy resin; wherein the bio-based DOPO derivative flame retardant DOPO-CUR is the bio-based DOPO derivative flame retardant DOPO-CUR described above; or, the bio-based DOPO derivative flame retardant DOPO-CUR is prepared by the preparation method described above.

[0040] The epoxy resin and DOPO-CUR are stirred at 120-150°C to obtain a uniform solution, 4,4'-diaminodiphenylmethane is added and stirred until transparent, poured into a mold, first vacuum dried at 90-110°C for 2-3 hours, and then vacuum dried at 140-160°C for 3-5 hours to obtain an epoxy resin containing DOPO-CUR.

[0041] Comparison of epoxy resins with different DOPO-CUR contents:

[0042] 1) Epoxy resin without DOPO-CUR:

[0043] In terms of flame retardancy, the fireproof UL94 grade is not passed (NR); the LOI value is only 24.0%; the peak heat release rate (PHRR) is 541.3kW / m 2 ; Total heat release (THR) is 78.5MJ / m 2 ; Total smoke production (TSP) is 45.2m 2 .

[0044] In terms of mechanical properties, the elastic modulus is 440.59Mpa, the elongation at break is 10.45%, the tensile strength is 50.60Mpa, the flexural modulus is 854.50Mpa, the flexural strength is 48.65Mpa, and the impact strength is 17.73KJ / m 2 .

[0045] 2) Epoxy resin containing 1wt% of DOPO-CUR:

[0046] In terms of flame retardant performance, the fireproof UL94 grade is not passed (NR); the LOI value is 28.1%.

[0047] 3) Epoxy resin containing 2 wt% of DOPO-CUR:

[0048] In terms of flame retardant performance, the fireproof UL94 grade is V-1; the LOI value is 30.2%.

[0049] 4) Epoxy resin containing 3 wt% of DOPO-CUR:

[0050] In terms of flame retardant performance, the fireproof UL94 grade is V-1; the LOI value is 30.7%.

[0051] 5) Epoxy resin containing 4 wt% DOPO-CUR:

[0052] In terms of flame retardant performance, the fireproof UL94 grade is V-0; the LOI value is 31.2%.

[0053] 6) Epoxy resin containing 5 wt% of DOPO-CUR:

[0054] refer to Figure 4 , Figure 5 , Figure 6 In terms of flame retardancy, the UL94 fireproof grade is V-0; the LOI value is 32.6%; the peak heat release rate (PHRR) is 467.2kW / m 2 ; Total heat release (THR) is 75.1MJ / m 2 ; Total smoke production (TSP) is 43.6m 2 .

[0055] In terms of mechanical properties, the elastic modulus is 693.72Mpa, the elongation at break is 12.51%, the tensile strength is 75.98Mpa, the flexural modulus is 1470.03Mpa, the flexural strength is 76.13Mpa, and the impact strength is 11.90KJ / m 2 .

[0056] By comparison, the flame retardant properties are significantly improved, while the mechanical properties remain good.

[0057] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A bio-based DOPO derivative flame retardant, characterized in that: The structural formula of the flame retardant is Abbreviated as DOPO-CUR.

2. The method for preparing a bio-based DOPO derivative flame retardant according to claim 1, characterized in that: The specific steps are as follows: S1. Weigh DOPO into a container, add solvent, and stir to mix evenly; S2, adding curcumin and triethylamine into a container, and stirring evenly under a stirrer; S3, adding carbon tetrachloride dropwise into the container under stirring, and controlling the temperature within 10°C during the addition process; S4, react at room temperature for 8 to 12 hours; S5, extracting and washing the reaction solution with hydrochloric acid, sodium bicarbonate, and deionized water in sequence to obtain a lower layer of viscous liquid; S6. The separated lower layer of viscous liquid is subjected to reduced pressure distillation to remove the solvent in the reaction, and the product DOPO-CUR is obtained by vacuum drying after precipitation.

3. The method for preparing a bio-based DOPO derivative flame retardant according to claim 2, characterized in that: In the S2, the molar ratio of curcumin to DOPO is 1:1.8-2.2, and the molar ratio of triethylamine to DOPO is 1:0.8-1.2; in the S3, the molar ratio of carbon tetrachloride to DOPO is 1:0.8-1.

2.

4. The method for preparing a bio-based DOPO derivative flame retardant according to claim 3, characterized in that: The molar ratio of the curcumin, DOPO, carbon tetrachloride and triethylamine is 1:2:2:

2.

5. The method for preparing a bio-based DOPO derivative flame retardant according to claim 4, characterized in that: The solvent is one or more of dichloromethane, ethyl acetate, acetonitrile, tetrahydrofuran and chloroform.

6. The method for preparing a bio-based DOPO derivative flame retardant according to claim 5, characterized in that: The mass of the solvent used is 3 to 8 times the mass of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

7. A method for preparing a bio-based DOPO derivative flame retardant as claimed in claim 6, characterized in that: In S5, the concentration of hydrochloric acid used for extraction and washing is 0.05-0.15 mol / L, and the concentration of sodium bicarbonate used for extraction and washing is 0.05-0.15 mol / L; the extraction and washing are performed 2-3 times with hydrochloric acid, sodium bicarbonate and deionized water respectively.

8. The method for preparing a bio-based DOPO derivative flame retardant according to claim 7, characterized in that: The stirrer is a heat-collecting magnetic stirrer; in S3, a constant pressure dropping funnel is used for dropwise addition.

9. An application of a bio-based DOPO derivative flame retardant, characterized in that: The bio-based DOPO derivative flame retardant DOPO-CUR is used to prepare flame-retardant epoxy resin; wherein the bio-based DOPO derivative flame retardant DOPO-CUR is the bio-based DOPO derivative flame retardant DOPO-CUR according to claim 1; or, the bio-based DOPO derivative flame retardant DOPO-CUR is prepared by the preparation method according to any one of claims 2 to 8.

10. The use of a bio-based DOPO derivative flame retardant as claimed in claim 9, characterized in that: The epoxy resin and DOPO-CUR are stirred at 120-150°C to obtain a uniform solution, 4,4'-diaminodiphenylmethane is added and stirred until transparent, poured into a mold, first vacuum dried at 90-110°C for 2-3 hours, and then vacuum dried at 140-160°C for 3-5 hours to obtain an epoxy resin containing DOPO-CUR.

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