阅读说明：本技术 一种无机有机含dopo阻燃剂及其制备方法和应用 (Inorganic-organic DOPO-containing flame retardant and preparation method and application thereof ) 是由 李薇 李昶红 赖华 李玉林 黄耿 于 2020-06-29 设计创作，主要内容包括：一种无机有机含DOPO阻燃剂及其制备方法和应用,涉及有机无机杂化新材料技术领域,本发明从分子设计角度出发,将反应型阻燃剂和有机无机杂化结构相结合,制备出有机无机杂化的含DOPO阻燃剂,通过在有机和无机相之间引入化学键作用,改善了阻燃剂和不饱和聚酯树酯材料之间的相容性,本发明制备的含无机有机杂化DOPO阻燃剂阻燃效果优异,与基材的相容性好。并且本发明制备上述无机有机杂化DOPO阻燃剂的工艺非常简单,反应温度都是在70℃以下,安全性高,对于设备的要求较低,更易于在工业上规模化生产应用。(The invention discloses an inorganic-organic DOPO-containing flame retardant and a preparation method and application thereof, and relates to the technical field of organic-inorganic hybrid new materials. The process for preparing the inorganic-organic hybrid DOPO flame retardant is very simple, the reaction temperature is below 70 ℃, the safety is high, the requirement on equipment is low, and the preparation method is easy to realize industrial large-scale production and application.)

1. An inorganic-organic DOPO-containing flame retardant has a structural formula as follows:

2. a method for preparing an inorganic-organic DOPO-containing flame retardant, comprising the steps of:

under the protection of nitrogen, adding graphene oxide and phosphorus flame retardant DOPO into a DMF solution as a reaction solvent, stirring and refluxing for reaction at the reaction temperature of 55-65 ℃, obtaining a turbid liquid containing black brown solid particles after the reaction, separating the black brown solid particles, and drying to obtain inorganic and organic DOPO-containing flame retardant PGO, wherein the structural formula of the PGO is as follows:

3. a method for preparing an inorganic-organic DOPO-containing flame retardant, comprising the steps of:

adding PGO, a silane coupling agent KH-560, ethanol and a 5% by mass HCl solution into the mixture under the protection of nitrogen, stirring and refluxing for reaction at the reaction temperature of 45-55 ℃, obtaining a turbid liquid containing black solid particles after the reaction, separating the black solid particles, and drying to obtain the inorganic and organic flame retardant HPGO containing DOPO, wherein the structural formula of the HPGO is as follows:

4. the method of preparing an inorganic-organic DOPO-containing flame retardant according to claim 2, wherein:

the mass ratio of the graphene oxide to the phosphorus flame retardant DOPO is 1: 6.

5. the method of preparing an inorganic-organic DOPO-containing flame retardant according to claim 3, characterized in that:

the ratio of the PGO to the silane coupling agent KH-560 is that every 0.5g of PGO corresponds to 50mL of the silane coupling agent KH-560;

the volume ratio of the silane coupling agent KH-560 to the ethanol to HCl solution is 5: 20: 2.

6. use of the inorganic-organic DOPO-containing flame retardant of claim 1 as a flame retardant for resin articles.

7. Use of the inorganic-organic DOPO-containing flame retardant of claim 1 as a flame retardant for unsaturated polyester materials.

8. Use of the inorganic-organic DOPO-containing flame retardant prepared in claim 3 as an enhancer for unsaturated polyester materials.

9. The use of an inorganic-organic DOPO-containing flame retardant as an enhancer for unsaturated polyester materials according to claim 8, wherein:

heating a proper amount of unsaturated polyester resin in an environment of 65-75 ℃, heating a proper amount of HPGO and MDA at 115-125 ℃ to form a mixed solution, cooling the mixed solution of HPGO and MDA to below 75 ℃, mixing the mixed solution of HPGO and MDA with the unsaturated polyester resin, uniformly stirring, and curing to obtain the unsaturated polyester composite material, wherein the content of HPGO in the unsaturated polyester composite material is 2.5-3.5%.

10. An article of unsaturated polyester material characterized by: the HPGO comprises 2.5-3.5% of HPGO, and the structural formula of the HPGO is as follows:

Technical Field

The invention relates to the technical field of organic-inorganic hybrid new materials, in particular to an inorganic-organic DOPO-containing flame retardant, and a preparation method and application thereof.

Background

At present, in the fields of airplanes, motor cars, automobiles and aerospace, composite high polymer materials are widely applied to manufacturing larger load-bearing structural materials and parts due to light weight, high strength and strong rigidity, and part of the composite high polymer materials also have the characteristics of low viscosity, low price, good molding and processing properties and the like, so that the composite high polymer materials are widely used for manufacturing internal equipment, decoration and coating materials of the transportation tools.

A great deal of high polymer materials are widely applied to various vehicles to bring certain hidden dangers, and many high polymer materials have a fatal defect of high flammability, which inevitably brings about serious fire safety problems and directly influences the life and property safety of people, so that the flame retardance of the high polymer materials is greatly concerned. The nano composite organic-inorganic hybrid material has great application potential in the aspect of flame retardant property, and how to improve the compatibility of the inorganic material and the organic material is a problem which needs to be solved urgently by the organic-inorganic hybrid material at present, and few reports about inorganic-organic hybrid flame retardants containing DOPO are reported at present.

Disclosure of Invention

One of the purposes of the invention is to provide an inorganic and organic DOPO-containing flame retardant which has excellent flame retardant effect and good compatibility with a high molecular polymer substrate.

In order to achieve the above object, the present invention provides an inorganic-organic DOPO-containing flame retardant,

the structural formula is as follows:

in addition, the present invention also provides a method of preparing an inorganic-organic DOPO-containing flame retardant, which in one embodiment of the present invention comprises the steps of:

under the protection of nitrogen, adding graphene oxide and phosphorus flame retardant DOPO into a DMF solution as a reaction solvent, stirring and refluxing for reaction at the reaction temperature of 55-65 ℃, obtaining a turbid liquid containing black brown solid particles after the reaction, separating the black brown solid particles, and drying to obtain inorganic and organic DOPO-containing flame retardant PGO, wherein the structural formula of the PGO is as follows:

wherein the mass ratio of the graphene oxide to the phosphorus flame retardant DOPO is 1: 6.

in another embodiment of the present invention, the above method for preparing an inorganic-organic DOPO-containing flame retardant comprises the steps of:

under the protection of nitrogen, adding the prepared PGO, the silane coupling agent KH-560, ethanol and 5% by mass of HCl solution, stirring, refluxing and reacting at the reaction temperature of 45-55 ℃, obtaining a turbid liquid containing black solid particles after reaction, separating the black solid particles, and drying to obtain the inorganic and organic flame retardant HPGO containing DOPO, wherein the structural formula of the HPGO is as follows:

wherein the ratio of PGO to silane coupling agent KH-560 is 50mL of silane coupling agent KH-560 per 0.5g of PGO;

the volume ratio of the silane coupling agent KH-560 to the ethanol to HCl solution is 5: 20: 2.

in addition, the invention also provides application of the inorganic and organic DOPO-containing flame retardant as a flame retardant for resin products.

Further, the application of the inorganic and organic DOPO-containing flame retardant as the flame retardant of the unsaturated polyester material is disclosed.

In addition, the invention also provides application of the prepared inorganic and organic flame retardant containing DOPO, namely HPGO, as an unsaturated polyester material reinforcing agent.

Specifically, a proper amount of unsaturated polyester resin is placed in an environment with the temperature of 65-75 ℃ for heating, a proper amount of HPGO and MDA are heated at the temperature of 115-125 ℃ to form a mixed solution, the mixed solution of HPGO and MDA is cooled to the temperature below 75 ℃, the mixed solution of HPGO and MDA is mixed with the unsaturated polyester resin and uniformly stirred, and the unsaturated polyester composite material is obtained after curing, wherein the content of HPGO in the unsaturated polyester composite material is 2.5-3.5%.

Finally, based on the fact that the HPGO has a reinforcing effect on the unsaturated polyester material, the invention also provides an unsaturated polyester material product, wherein the component of the product contains 2.5% -3.5% of HPGO.

Aiming at the problems existing in the current unsaturated polyester flame retardant situation, the invention combines a reactive flame retardant with an organic-inorganic hybrid structure from the perspective of molecular design to prepare an organic-inorganic hybrid DOPO-containing flame retardant, and can improve the compatibility between the flame retardant and an unsaturated polyester resin material by introducing a chemical bond effect between organic and inorganic phases. The unsaturated polyester material added with the flame retardant is subjected to flame retardance and mechanical property tests, and the flame retardant containing the inorganic-organic hybrid DOPO is proved to have excellent flame retardance and good compatibility with base materials. Particularly, the flame retardant HPGO provided by the invention has excellent flame retardant effect, and meanwhile, the tensile strength and the impact strength of an unsaturated polyester material can be obviously improved. In addition, the process for preparing the inorganic-organic hybrid DOPO flame retardant is very simple, the reaction temperature is below 70 ℃, the safety is high, the requirement on equipment is low, and the industrial large-scale production and application are easier.

Description of the drawings:

FIG. 1 is a diagram showing the reaction solution containing PGO obtained in the example before and after the reaction solution is left to stand;

fig. 2 is an infrared spectrum of graphene oxide;

FIG. 3 is an IR spectrum of PGO prepared in the example;

FIG. 4 is an infrared spectrum of DOPO.

Detailed Description

In order to facilitate the understanding of those skilled in the art, the present invention will be further described with reference to the following examples, which are not intended to limit the present invention. It should be noted that the following examples are carried out in the laboratory, and it should be understood by those skilled in the art that the amounts of the components given in the examples are merely representative of the proportioning relationship between the components, and are not specifically limited.

1. Preparation of Graphene Oxide (GO).

(1) Pre-oxidation: weighing 7.5g of potassium persulfate and 7.5g of phosphorus pentoxide, weighing 40mL of concentrated sulfuric acid, adding into a three-neck flask (equipped with a thermometer), placing into an electric heating jacket, stirring, heating to about 80 ℃, and reacting until the solution is colorless and transparent. At this point, 10g of graphite was added and the reaction was carried out for about 5 hours. After the reaction is finished, pouring the obtained solution into a beaker filled with water, filtering and washing until the solution is neutral, and then putting the residue into an oven at about 100 ℃ for drying for about 3 hours.

(2) And (3) oxidation: firstly, putting part of concentrated sulfuric acid and dried filter residue into a three-neck flask (ice water bath), stirring and dispersing, weighing 50g of potassium permanganate, and slowly adding into the flask for reaction (controlling the temperature within 35 ℃). The remaining concentrated sulfuric acid solution was added thereto and reacted at a temperature of 35 ℃ for about 3 hours. After the reaction, the obtained reaction solution was poured into a beaker and diluted with water. Adding hydrogen peroxide dropwise until the solution turns from reddish brown to yellow and no bubbles are generated, and removing excessive potassium permanganate. Standing for a period of time.

(3) Acidifying: the resulting solution was washed with 30% hydrochloric acid, and the upper layer liquid was poured off after standing for layering, and this operation was repeated three times.

(4) The preparation method comprises the following steps: and (4) carrying out centrifugal operation on the liquid obtained by acidification treatment, and washing the obtained solid with water until the upper-layer solution is neutral after centrifugation. Filtering, dispersing the solid with water, and placing in an oven at about 58 deg.C for about 24 h. Finally obtaining dark brown graphene oxide solid.

2. Preparation of graphene oxide-containing DOPO (PGO).

Connecting the three-neck flask with a condensing reflux device and introducing N₂Weighing 1g of self-made GO (to say itIt should be noted that GO can be made by oneself or purchased from a market without strict limitation) and 6g of phosphorus flame retardant DOPO are added into a flask, 200ml of dmf solution is measured as a reaction solvent and added into the flask, and after stirring and heating to 55 ℃ -65 ℃ (preferably at 60 ℃), the reaction is carried out for about 6 hours, so as to obtain a turbid liquid containing blackish brown solid particles, as shown in fig. 1. After cooling the reaction solution, the reaction solution was placed in a centrifugal pump for centrifugal operation. And pouring the upper layer solution, uniformly dispersing the lower layer solid in a small amount of water, pouring the mixture into a beaker, and drying the beaker at the temperature of 55 ℃ for 2 days to obtain the dry black solid PGO. The principle of the preparation process is as follows:

3. preparation of a silicone-containing graphene oxide DOPO flame retardant (HPGO).

Connecting the three-neck flask with a condensing reflux device and introducing N₂0.5g of PGO is weighed, 50mL of silane coupling agent KH-560, 20mL of 5% HCl and 200mL of ethanol solution are weighed as reaction solvents and added into a flask, and after stirring and heating to 45-55 ℃ (preferably at 50 ℃), the reaction lasts for about 8 hours, and turbid liquid containing black solid particles is obtained.

After cooling the reaction solution, the reaction solution was placed in a centrifugal pump for centrifugal operation. And pouring out the upper layer solution, uniformly dispersing the lower layer solid in a small amount of water, pouring into a beaker, and drying in an environment at 50 ℃ for 2 days to obtain the dry black solid HPGO. The principle of the preparation process is as follows:

and 4, manufacturing GO/UPR, PGO/UPR and HPGO/UPR flame-retardant composite material samples.

(1) Preparing: placing the whole bottle of Unsaturated Polyester Resin (UPR) in an environment of 70 ℃ for heating, improving the fluidity and facilitating pouring and mixing; the temperature of a vacuum oven is adjusted to 90 ℃, and the temperature of a common oven is adjusted to 120 ℃; the mold for making the sample was sealed with a black tape in advance.

(2) Mixing: weighing an appropriate amount of Unsaturated Polyester Resin (UPR) in a 250ml beaker, then continuously placing the beaker in an environment of 65-75 ℃ (preferably 70 ℃) for heating, weighing a certain amount of GO (1%, 3%, 5%) and a certain amount of 4, 4' -diaminodiphenylmethane in another beaker, placing the beaker in an environment of 115-125 ℃ (preferably 120 ℃) for heating to obtain a mixed solution. And taking out the beaker filled with the UPR and the beaker filled with the mixed solution of GO and MDA, cooling to below 75 ℃, mixing the beaker and the beaker, and uniformly stirring.

(3) Pouring a mold: the mixed system was poured uniformly into the prepared molds. Note that: not overfill or unfilled corners.

(4) Air bubble extraction: because bubbles are inevitably present in the mixed system and influence the measurement result, the filled mold must be pumped. And (3) placing the filled mould into a vacuum drying box at about 90 ℃ for air suction to remove air bubbles.

(5) High-temperature curing: after the bubbles are removed by blowing, the filled mould is put into a common oven at about 120 ℃ for curing for about 4 hours.

The other two samples were prepared by the same procedure as above, but the temperatures for the high temperature curing were different, 140 ℃ and 180 ℃.

And 5, analyzing infrared spectrograms of GO, PGO and HPGO.

FIG. 2 is an infrared spectrum of GO. As can be seen from FIG. 2, although there were originally few functional groups on the graphite, the graphite reacted with concentrated H₂SO₄And KMnO₄After the reaction, the product GO shows some characteristic peaks: 1091.71cm^-1Characteristic peak of epoxy group at position 1533.41cm^-1The characteristic peak of the bond-C ═ O, which is due to the formation of many oxygen-containing groups (e.g., -COOH, -OH, -C ═ O, etc.) by graphite during oxidation. Therefore, the fact that GO is successfully prepared is proved by a plurality of characteristic peaks appearing in the infrared spectrogram of GO.

FIG. 3 is a PGO infrared spectrum. As can be seen from FIG. 3, the epoxy group of GO reacted with DOPO to make 1091.71cm^-1The characteristic peak of the epoxy group at (b) disappeared, i.e. it was confirmed that DOPO did react with the epoxy group on GO.

FIG. 4 is an infrared spectrum of DOPO having a band at 2436.09cm, as can be seen from FIG. 4^-1P-H bond of (A), while the infrared spectrum of PGO does notHas characteristic peak of P-H bond, so that the DOPO on the PGO is completely removed. As DOPO reacted with GO, 1724.36cm of each appeared in FIG. 3^-1Characteristic peaks of P-Ph bond at position and 1199.72cm^-1P ═ O bond characteristic peak at (a). By combining the above, it is proved that the DOPO modified graphene oxide PGO has been successfully prepared.

And 6, testing the performance of the GO/UPR, PGO/UPR and HPGO/UPR flame-retardant composite material.

The results of the thermal analysis (thermal stability) test of pure UPR and other UPR flame retardant composites are shown in Table 1:

TABLE 1 pure UPR, GO/UPR, PGO/UPR and HPGO/UPR thermal analysis test data

As can be seen from the data obtained from the test in Table 1, after GO, PGO and HPGO are respectively added to unsaturated polyester resin to prepare the composite material, the initial decomposition temperature T of the material_oAnd maximum decomposition temperature T_maxCompared with a pure unsaturated polyester resin material, GO is reduced due to the fact that GO has oxygen-containing groups and thermal instability, the thermal stability of the composite material is reduced, the carbon residue rate is increased from 16.5% to 22.3%, and the adding of GO promotes the formation of a carbon layer, and a PGO/UPR system and an HPGO/UPR system are improved compared with the GO/UPR system, and the two main reasons are as follows: (1) after PGO and HPGO are added into the UPR, the graphite has good thermal conductivity, and when the graphite is subjected to high temperature from the outside, the heat of the material is transferred from the outside to the inside, so that the heat is transferred and is not concentrated on the surface for combustion; (2) PGO and HPGO are both of a lamellar structure, so that the thermal barrier property is good, and gas released in the combustion process of the system is still retained in the system. Due to the two reasons, T of PGO/UPR and HPGO/UPR materials_oAnd T_maxIs improved.

The pure unsaturated polyester resin has a carbon residue rate of 16.5% at 800 ℃, and in GO/UPR, PGO/UPR and HPGO/UPR composite materials, the carbon residue rate increases with the increase of the use amounts of GO, PGO and HPGO, which shows that GO, PGO and HPGO have a certain effect on the flame retardance of the materials. The carbon residue rate of the HPGO/UPR composite material at 800 ℃ under the same condition is higher than that of the GO/UPR and PGO/UPR composite materials, namely the carbonization effect of the HPGO at high temperature is the best, and the thermal stability of the material is better.

The flame performance test (limiting oxygen index and vertical burn test) results for pure UPR and other UPR flame retardant composites are shown in Table 2:

TABLE 2 LOI and UL-94 test data

As can be seen from Table 2, after GO is added into the unsaturated polyester resin, the LOI value is not obviously changed, and the dripping phenomenon still occurs in the vertical burning test. This is because GO contains a large amount of oxygen groups on the surface, and in the combustion process, at first, has taken place the reduction phenomenon, makes GO reduce into graphite alkene, and graphite alkene that obtains after the reduction forms the charcoal layer and just can play fire-retardant effect, so GO's fire resistance can not be ideal. However, after the P element modified graphene oxide PGO is added into the UPR material, the LOI value is remarkably improved, UL-94 reaches V-0 level, and no dripping phenomenon occurs during combustion. The oxidation degree is gradually reduced due to the reaction of oxygen-containing groups on the surfaces of DOPO and GO, so that the reduction degree of GO into graphene is reduced, and the flame retardant property is improved due to the introduction of phosphorus. The limit oxygen index LOI value of the HPGO/UPR composite material is the highest, because the silane coupling agent KH-560 reacts with carboxyl on PGO, the oxidation degree is reduced, the degree of reduction into graphene is further reduced, and the combined action of P, Si elements is beneficial to improving the LOI value and the flame retardant level.

The data relating to mechanical testing of pure UPR and other UPR composites is shown in Table 4:

TABLE 3 UPR composite mechanical Property test data

As is clear from Table 3, the tensile strength of pure UPR was 54.1MPa, and the impact strength was 13.7kJ/m². When GO is added into UPR, compared with pure UPR, the tensile strength and impact strength of the material are both remarkably reduced, and within a certain range, the mechanical property of the GO/EP composite material is gradually improved along with the increase of the GO dosage, but the mechanical property of the material is not increased or inversely reduced after excessive GO is added. This is because GO has many oxygen-containing groups on its surface, and their compatibility with epoxy resin is not good, so too much GO is added and is difficult to disperse into the system, resulting in the reduction of mechanical properties of the material. When PGO is added into a UPR system, the mechanical properties of the PGO/UPR composite material are improved compared with those of the GO/UPR composite material, because the oxygen-containing groups on the surface of the phosphorus element modified graphene oxide PGO are reduced, so that the compatibility of the PGO with the UPR material is improved, the dispersibility in UPR is also improved, and a space network structure is formed. The PGO/UPR composite material is the same as the GO/UPR composite material, and the mechanical property of the material is firstly improved and then reduced along with the increase of the dosage of PGO. When HPGO is added into UPR to prepare the composite material, the tensile strength and the impact strength of the composite material are obviously improved, and the mechanical properties of the composite material are better than those of pure UPR, GO/UPR and PGO/UPR. The oxygen-containing groups on the surface of the HPGO modified graphene oxide containing phosphorus and silicon elements are greatly reduced, so that the HPGO is better in compatibility with UPR and better in dispersibility, and when the HPGO is impacted by external force, energy is transferred to a sheet layer of the HPGO, external acting force is effectively shared, and excellent mechanical properties are shown. However, with the addition of the HPGO, the mechanical property of the HPGO/UPR composite material is improved and then reduced. The larger the HPGO is, the lower the system dispersibility and the higher the viscosity, so that the mechanical property is reduced, and when the HPGO is used in an amount of 2.5-3.5% (especially 3%), the mechanical property of the sample is obviously improved.

In the embodiment, from the perspective of molecular design, the reactive flame retardant and the organic-inorganic hybrid structure are combined to prepare the organic-inorganic hybrid DOPO-containing flame retardant, and the compatibility between the flame retardant and the unsaturated polyester resin material is improved by introducing a chemical bond effect between organic and inorganic phases. Tests on flame retardance and mechanical properties of the unsaturated polyester material added with the flame retardant prove that the flame retardant containing the inorganic-organic hybrid DOPO has excellent flame retardance and good compatibility with base materials. Particularly, the flame retardant HPGO has an excellent flame retardant effect, can obviously improve the tensile strength and the impact strength of the unsaturated polyester material, and can be used as a flame retardant and a reinforcing agent of the unsaturated polyester material. In addition, the process for preparing the inorganic-organic hybrid DOPO flame retardant is very simple, the reaction temperature is below 70 ℃, the safety is high, the requirement on equipment is low, and the method is favorable for industrial large-scale production and application.

The above embodiments are preferred implementations of the present invention, and the present invention can be implemented in other ways without departing from the spirit of the present invention.

Finally, it should be emphasized that some of the descriptions of the present invention have been simplified to facilitate the understanding of the improvements of the present invention over the prior art by those of ordinary skill in the art, and that other elements have been omitted from this document for the sake of clarity, and those skilled in the art will recognize that these omitted elements may also constitute the content of the present invention.