CN105001451A - Graphene containing DOPO group and preparation method thereof - Google Patents

Abstract

The invention belongs to the field of material technology, in particular to a graphene containing a phosphorus-based flame retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) group and its preparation method. The specific preparation steps are as follows: the graphene and DOPO are grafted with specific chemical groups through chemical reaction to obtain DOPO with epoxy groups and graphene with amino groups. Then react DOPO with epoxy group and graphene with amino group to obtain graphene with DOPO group. The graphene with DOPO groups can improve the flame retardancy of high polymers and their composite materials, and at the same time improve or keep the mechanical properties of materials as much as possible. The graphene preparation method with DOPO groups has mild process conditions, is simple and easy to implement, and is suitable for mass production.

Description

A kind of graphene containing DOPO group and preparation method thereof

technical field

The invention belongs to the field of material technology, in particular to a graphene containing phosphorus-based flame retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and a preparation method thereof. It can be used to improve the flame retardancy and mechanical properties of high polymers and their composite materials.

Background technique

Graphene is a new material with a single-layer sheet structure composed of carbon atoms. It is a planar film composed of carbon atoms with sp2 hybrid orbitals to form a hexagonal honeycomb lattice. It is a two-dimensional material with a thickness of only one carbon atom. Since Andre Geim and Konstantin Novoselov successfully separated graphene from graphite in the laboratory in 2004, graphene has become a research hotspot in recent years because of its unique structure, good electrical properties and mechanical properties. At the same time, since graphene can form a dense carbon layer on the surface when it burns, it can be used as a flame retardant additive, and some studies have proved its flame retardant effect. Although the addition of graphene to polymers and their composites can improve the mechanical properties of the material and reduce the heat release rate of the material, the extent to which the addition of graphene can improve the combustion test characteristics of the material needs to be further strengthened to meet the requirements of the composite material. Wide application in engineering.

9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is a reactive phosphorus-based flame retardant intermediate, which has excellent flame retardancy, smokeless and non-toxic , due to the presence of P-C bonds, it has good chemical stability, water resistance, permanent flame retardancy and no migration. DOPO can be used for flame retardant of PET, PBT, PBN, PEN and other polyesters, flame retardant of epoxy resin and chemical modification of polymer materials such as polyvinyl alcohol. It is also widely used in plastics for electronic equipment, copper lining laminates, circuit boards, photosensitive materials and luminescent materials for flame retardancy abroad. DOPO has a six-membered phosphorus heterocyclic structure, and P has a lone pair of electrons, which is prone to nucleophilic addition reactions. Although the addition of flame retardant DOPO to polymers can improve their flame retardant performance, it will also deteriorate the mechanical properties of polymers to a certain extent.

Guobo Huang et al. found that polyvinyl alcohol and graphene-based nanocomposite polymer solutions were blended, and their flame retardancy was evaluated by cone calorimetry. It is proved that the graphene nanosheets can significantly reduce the peak heat release rate and prolong the ignition time of the composite material, which has a great influence on the fire performance. Chung Yuan et al found that DOPO-PN synthesized by the addition reaction of DOPO and 4-hydroxybenzaldehyde has a certain influence on the flame retardant properties of composite materials. It is proved by experiments that DOPO-PN can make composite materials pass UL94V-0 test The limiting oxygen index of the material has been greatly improved. According to the patent ZL 201310008589.5, the graphene is firstly modified with silane containing isocyanate, and then the DOPO structure is introduced through the sol-gel method to prepare a composite structure containing DOPO and exfoliated graphene, which can improve the polymerization efficiency. flame retardant properties.

In order to obtain a flame-retardant material that simultaneously improves the flame-retardant properties and mechanical properties of the material, this patent provides a preparation method for graphene containing DOPO groups. By grafting DOPO onto graphene, DOPO and graphene can be used simultaneously. Advantages, develop strengths and avoid weaknesses, and form complementarities. The method has the characteristics of simple process, and the obtained flame retardant is highly efficient and stable, and has important practical application value.

Contents of the invention

The object of the present invention is to provide a kind of graphene containing DOPO group and preparation method thereof, this graphene can be used in high polymer and its composite material, while improving composite material flame retardancy, improve or keep as much as possible The mechanical properties of the material.

In order to achieve the above object, the solution of the present invention is: firstly, the graphene and DOPO are chemically reacted with specific chemical groups to obtain modified DOPO and graphene. Then react the modified DOPO with graphene to obtain graphene with DOPO groups.

A kind of graphene that the present invention proposes contains DOPO group, and its structural feature is as follows:

Where: R is phenyl or methylene, n≥2.

In the present invention, the phenyl group is or or One of, methylene is -CH ₂ - or , X≥2.

The preparation method of the graphene that the present invention proposes containing DOPO group, concrete steps are:

(1) Dissolve graphite oxide in a solvent, disperse by ultrasonic, add diamine and dicyclohexylcarboimide (DCC), wherein the weight ratio of graphite oxide to diamine is 1:150, diamine and dicyclohexyl carbon The weight ratio of imide (DCC) is 1:100, stirred and refluxed in an oil bath at 65~85°C for 8~24h. After the reaction, filter and wash repeatedly.

(2) Add DOPO and solvent to the four-neck flask under nitrogen protection, heat and stir to 70~85°C, after DOPO is completely dissolved, add p-benzoquinone within 1.5h, the weight ratio of DOPO to benzoquinone is 1:150 , Stir the reaction at 90°C for 2~4h. The resulting precipitate was cooled to room temperature, filtered, washed several times, and dried to obtain a white powder, and then recrystallized with a solvent to obtain a white solid after drying.

(3) Put the white solid obtained in step (2) and epichlorohydrin into a four-necked flask at a weight ratio of 1:150, add an appropriate amount of catalyst, and react at 65~75°C for 18~24h. The resulting product was washed several times and dried to obtain DOPO with epoxy groups.

(4) Dissolve the epoxy group DOPO obtained in step (3), and heat and stir in an oil bath at 70-85°C for 12 hours with the aminated graphene obtained in step (1) at a weight ratio of 1:150. The obtained product was washed several times with solvent and dried for 12 hours. Graphene with DOPO groups is obtained.

In the present invention, the graphene includes single-layer and multi-layer graphene.

In the present invention, the diamine structural formula described in step (3) is as follows:

where R is phenyl ( or or one of) or methylene (-CH ₂ -) or (X≥2), n≥2.

In the present invention, the solvents described in steps (2), (3) and (4) include methanol, ethanol, propanol, dimethyl sulfoxide, benzene, toluene, xylene, methylene chloride, chloroform, acetone, butyl One or more of ketone, tetrahydrofuran or dimethylformamide, etc.

In the present invention, the amount of solvent used in steps (1), (2), (3) and (4) should meet the weight ratio of graphene and solvent or DOPO and solvent is 1-150.

In the present invention, the catalyst in step (3) is one or more of sodium methoxide, potassium hydroxide or sodium hydroxide.

The beneficial effects of the present invention are:

(1) A highly efficient and stable flame retardant can be obtained by grafting DOPO groups onto graphene.

(2) This kind of graphene with DOPO group can be used for the flame retardancy of high polymers and their composite materials. While improving the flame retardancy of the material, the mechanical properties of the material should be maintained or improved as much as possible.

(3) The preparation method is simple and effective, the process conditions are mild, and it is suitable for mass production.

Description of drawings

Fig. 1 is the infrared spectrogram of the graphene grafted DOPO group of embodiment 1. Among them, the peak around 1191cm ^-1 represents the vibration peak of P=O; the peak around 1075cm ^-1 represents the vibration peak of POC; the peak around 1410cm ^-1 represents the vibration peak of hydroxyl. All these indicate that graphene-grafted epoxy DOPO has been successfully prepared.

Detailed ways

The present invention is further described below by way of examples.

Example 1

(1) Dissolve 0.5g of graphite oxide in DMF solution and ultrasonically disperse, add 50ml of ethylenediamine and 3g of dicyclohexylcarboimide (DCC), stir and reflux in an oil bath at 65°C for 8h. After the reaction, filter, and then wash repeatedly with DMF solution until all excess ethylenediamine solution is washed away.

(2) Add 12g DOPO and 300mL toluene to a four-neck flask under nitrogen protection, heat and stir to 70°C, after DOPO is completely dissolved in toluene, add 5g of benzoquinone within 1.5h, and then stir and react at 90°C for 2h. The resulting precipitate was cooled to room temperature, filtered, washed several times with toluene, and dried to obtain a white powder, which was then reconstituted with ethanol, and dried to obtain a white solid.

(3) Add 32.4 g of white solid and 100 mL of epichlorohydrin into a four-neck flask, add 15 g of sodium methoxide as a catalyst, and react at 65 ° C for 18 h. The resulting product was washed several times with methanol and dried to obtain DOPO with epoxy groups.

(4) The epoxy group DOPO obtained in step (3) was dissolved, and heated and stirred with the aminated graphene obtained in step (1) in an oil bath at 70°C for 12 hours. The obtained product was washed several times with absolute ethanol and dried for 12 hours. Graphene with DOPO groups is obtained.

Example 2

(1) Dissolve 0.4g of graphite oxide in toluene solution for ultrasonic dispersion, add 50ml of triethylenetetramine and 3.5g of dicyclohexylcarboimide (DCC), stir and reflux in an oil bath at 67°C for 8.5h. After the reaction, filter and then wash repeatedly with toluene solution until all the excess triethylenetetramine solution is washed away.

(2) Add 12g DOPO and 300mL chlorobenzene to a four-neck flask under nitrogen protection, heat and stir to 72°C, after DOPO is completely dissolved in chlorobenzene, add 5g benzoquinone within 1.5h, then stir and react at 90°C for 2.5 h. The resulting precipitate was cooled to room temperature and filtered, washed several times with chlorobenzene, and dried to obtain a white powder, which was then reconstituted with ethanol to obtain a white solid after drying.

(3) Add 35g of white solid and 120mL of epichlorohydrin into a four-neck flask, add 15.5g of sodium methoxide as a catalyst, and react at 68°C for 18.5h. The resulting product was washed several times with methanol and dried to obtain DOPO with epoxy groups.

(4) The epoxy group DOPO obtained in step (3) was dissolved, and heated and stirred with the aminated graphene obtained in step (1) in an oil bath at 72°C for 12 hours. The obtained product was washed several times with absolute ethanol and dried for 12 hours. Graphene with DOPO groups is obtained.

Example 3

(1) Dissolve 0.6g of graphite oxide in THF solution for ultrasonic dispersion, add 60ml of p-phenylenediamine and 3g of dicyclohexylcarboimide (DCC), stir and reflux in an oil bath at 70°C for 12h. After the reaction, filter and then wash repeatedly with THF solution until all the excess p-phenylenediamine solution is washed away.

(2) Add 12g DOPO and 300mL toluene to a four-neck flask under nitrogen protection, heat and stir to 75°C, after DOPO is completely dissolved in toluene, add 5g of benzoquinone within 1.5h, and then stir and react at 90°C for 2.5h. The resulting precipitate was cooled to room temperature, filtered, washed several times with toluene, and dried to obtain a white powder, which was then reconstituted with ethanol and dried to obtain a white solid.

(3) Add 32.4 g of white solid and 150 mL of epichlorohydrin into a four-necked flask, add KOH (0.5 mol/L) as a catalyst, and react at 67 ° C for 19 h. The resulting product was washed several times with methanol and dried to obtain DOPO with epoxy groups.

(4) The epoxy group DOPO obtained in step (3) was dissolved, and heated and stirred with the aminated graphene obtained in step (1) in an oil bath at 77°C for 12 hours. The obtained product was washed several times with absolute ethanol and dried for 12 hours. Graphene with DOPO groups is obtained.

Example 4

(1) Dissolve 0.6g of graphite oxide in toluene solution and ultrasonically disperse, add 55ml of diethylenetriamine and 3.6g of dicyclohexylcarboimide (DCC), stir and reflux in an oil bath at 71°C for 9h. After the reaction, filter and then wash repeatedly with toluene solution until all the excess triethylenetetramine solution is washed away.

(2) Add 12g DOPO and 300mL chlorobenzene to a four-neck flask under nitrogen protection, heat and stir to 73°C, after DOPO is completely dissolved in chlorobenzene, add 5g benzoquinone within 1.5h, and then stir and react at 90°C for 2h . The resulting precipitate was cooled to room temperature and filtered, washed several times with chlorobenzene, and dried to obtain a white powder, which was then reconstituted with ethanol to obtain a white solid after drying.

(3) Add 33 g of white solid and 125 mL of epichlorohydrin into a four-neck flask, add KOH (0.5 mol/L) as a catalyst, and react at 70 ° C for 21 h. The resulting product was washed several times with methanol and dried to obtain DOPO with epoxy groups.

(4) The epoxy group DOPO obtained in step (3) was dissolved, and heated and stirred with the aminated graphene obtained in step (1) in an oil bath at 76°C for 12 hours. The obtained product was washed several times with absolute ethanol and dried for 12 hours. Graphene with DOPO groups is obtained.

Example 5

(1) Dissolve 0.7g of graphite oxide in DMF solution and ultrasonically disperse, add 70ml of ethylenediamine and 4g of dicyclohexylcarboimide (DCC), stir and reflux in an oil bath at 75°C for 15h. After the reaction, filter, and then wash repeatedly with DMF solution until all excess ethylenediamine solution is washed away.

(2) Add 12g DOPO and 300mL toluene to a four-neck flask under nitrogen protection, heat and stir to 71°C, after DOPO is completely dissolved in toluene, add 5g of benzoquinone within 1.5h, and then stir and react at 90°C for 2.5h. The resulting precipitate was cooled to room temperature, filtered, washed several times with toluene, and dried to obtain a white powder, which was then reconstituted with ethanol, and dried to obtain a white solid.

(3) Add 34g of white solid and 150mL of epichlorohydrin into a four-neck flask, add NaOH (0.5mol/L) as a catalyst, and react at 65°C for 24h. The resulting product was washed several times with methanol and dried to obtain DOPO with epoxy groups.

(4) The epoxy group DOPO obtained in step (3) was dissolved, and heated and stirred with the aminated graphene obtained in step (1) in an oil bath at 80°C for 12 hours. The obtained product was washed several times with absolute ethanol and dried for 12 hours. Graphene with DOPO groups is obtained.

The present invention has been described in detail above, and its purpose is to allow those familiar with this field to understand the content of the present invention and implement it, and can not limit the scope of protection of the present invention. Effect changes or modifications should be covered within the protection scope of the present invention.

Claims (8)

1. the Graphene containing DOPO group, described DOPO is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and it is characterized in that described Graphene makes graphenic surface with one or more DOPO groups by graft reaction, its structure is as follows:

Wherein: R is phenyl or methylene radical, n >=2.

2. the Graphene containing DOPO group according to claim 1, is characterized in that described phenyl is or or in one, described methylene radical is-CH ₂-or, X>=2.

3. a preparation method for the Graphene containing DOPO group as claimed in claim 1, is characterized in that concrete steps are as follows:

(1) graphite oxide is dissolved in solvent, utilizes ultrasonic disperse, add diamines and Dicyclohexylcarbodiimide, stirring and refluxing 8 ~ 24h in the oil bath of 65 ~ 85 DEG C; After reaction terminates, filter, repetitive scrubbing; Wherein: graphite oxide and diamines weight ratio are 1:150, the weight ratio of diamines and Dicyclohexylcarbodiimide is 1:100;

(2) under nitrogen protection in four-hole boiling flask, add DOPO and solvent, heated and stirred, to 70 ~ 85 DEG C, after DOPO dissolves completely, adds para benzoquinone in 1.5h, and DOPO and benzoquinones weight ratio are 1:150, stirring reaction 2 ~ 4h at 90 DEG C; Gained throw out is cooled to room temperature to filter, washing for several times, obtains white powder after drying, then uses solvent recrystallization, can obtain white solid after drying;

(3), in the four-hole boiling flask white solid obtained in step (2) and epoxy chloropropane added according to weight ratio 1:150, proper catalyst is added, at 65 ~ 75 DEG C of reaction 18 ~ 24h; By products therefrom washing for several times, the DOPO with epoxy group(ing) is obtained after drying;

(4) dissolved by the epoxide group DOPO that step (3) obtains, the amination Graphene obtained with step (1) is according to weight ratio 1:150 heated and stirred 12h in 70 ~ 85 DEG C of oil baths; The product solvent repetitive scrubbing several obtained, dry 12h; Obtain the Graphene with DOPO group.

4., according to the preparation method of a kind of Graphene containing DOPO group described in claim 3, it is characterized in that the Graphene applied comprises individual layer and multi-layer graphene.

5., according to the preparation method of a kind of Graphene containing DOPO group described in claim 3, it is characterized in that described in step (3), diamine structures formula is as follows:

Wherein R is phenyl or methylene radical, n >=2.

6., according to the preparation method of a kind of Graphene containing DOPO group described in claim 3, it is characterized in that one or more that solvent described in step (2), (3) and (4) comprises in methyl alcohol, ethanol, propyl alcohol, dimethyl sulfoxide (DMSO), benzene,toluene,xylene, methylene dichloride, chloroform, acetone, butanone, tetrahydrofuran (THF) or dimethyl formamide.

7. the preparation method of a kind of Graphene containing DOPO group according to claim 3, is characterized in that the weight ratio using the amount of solvent should meet Graphene and solvent or DOPO and solvent described in step (1), (2), (3) and (4) is 1 ~ 150.

8., according to the preparation method of a kind of Graphene containing DOPO group described in claim 3, it is characterized in that catalyzer described in step (3) is one or more in sodium methylate, potassium hydroxide or sodium hydroxide.