CN110240618A - A kind of phosphorus-containing aminated coupling agent and its preparation method and application - Google Patents

Abstract

The invention relates to a phosphorus-containing aminated coupling agent and its preparation method and application. The carbon fiber adopts the surface sizing treatment method of the above-mentioned substances. The phosphorus-containing aminated coupling agent is composed of phosphoric triamide and epoxy group coupling The preparation method of the phosphoric triamide is as follows: using phosphoric acid ester and ethylenediamine as raw materials, and preparing by heating and refluxing. The application of the phosphorus-containing aminated coupling agent can not only maintain the interfacial bonding performance between the carbon fiber and the epoxy resin, but also significantly enhance the flame retardancy of the carbon fiber epoxy resin composite material.

Description

A kind of phosphorus-containing aminated coupling agent and its preparation method and application

technical field

The invention relates to the preparation of a phosphorus-nitrogen coupling agent and the field of material fibers, in particular to a phosphorus-nitrogen-containing coupling agent for flame-retardant modification of the surface of carbon fibers, a preparation method thereof, and an application on the surface of carbon fibers.

Background technique

Carbon fiber has a series of excellent properties such as high specific strength, specific modulus, low density, corrosion resistance, electrical and thermal conductivity, and small thermal expansion coefficient. Advanced composite materials made of carbon fiber as a reinforcement have undeniable potential in the fields of aerospace, national defense, and national economy. Substitution and wide application are important boosts to promote the development of new materials in my country. With the development trend of composite structure and function integration, carbon fiber composite materials also face the same problem. Since the surface of carbon fiber is inert, in order to improve the wetting performance between the fiber and the matrix, the most commonly used modification method is carbon fiber surface modification, such as sizing treatment, coupling agent modification, electrochemical oxidation, plasma oxidation, etc. Among them, the coupling agent modification not only has the advantages of fast reaction speed, good dispersion, and low price, which are suitable for industrial applications, but also has two kinds of functional groups in the chemical structure, which can connect the fiber and the matrix through chemical bonds. The bonding between interfaces is stronger.

At present, the research on coupling agent modified composite materials has been done abroad but not much, while domestic research on carbon fiber epoxy composite material system modified by coupling agent is very little, which is difficult to be systematic and referential. Most of the researches on modified aminosilane coupling agents focus on the improvement of interfacial properties, but seldom pay attention to the demand for functionalization of composite materials in different fields. Due to the important application of carbon fiber epoxy composites in the aerospace field, in addition to focusing on interface properties, it is also expected that the composites have certain flame-retardant properties. The research on materials that meet such requirements is imminent.

Contents of the invention

In order to solve the above-mentioned problems existing in the prior art, so that the interfacial performance and flame-retardant performance of carbon fiber composite materials can meet the requirements at the same time, the present invention provides a phosphorus-containing aminated coupling agent for fiber surface flame-retardant modification and its preparation method and apply. The synthesis method involved in the invention is simple, easy to implement, stable and controllable. Using the coupling agent synthesized by the method to treat the fiber surface can not only maintain the bonding ability between the fiber and the resin matrix, but also significantly improve the flame-retardant performance of the composite material.

The present invention adopts the following technical scheme: a preparation method of a phosphorus-containing aminated coupling agent, comprising: adding the phosphoric triamide into a reactor, slowly raising the temperature under the protection of nitrogen, and adding the epoxy-based coupling agent one by one Add it dropwise into the reaction system, keep a constant stirring speed, and react at 40~60℃ for 30min~1h.

In a preferred embodiment of the present invention, the phosphoric triamide is prepared by reacting phosphoric acid ester and ethylenediamine at the boiling point of ethylenediamine for 1-3 hours under the protection of nitrogen.

The structural formula of described phosphoric acid ester is:

.

The structural formula of described ethylenediamine is:

.

Described phosphoric triamide structural formula is:

.

In a preferred embodiment of the present invention, the epoxy-based coupling agent is γ-(2,3-glycidoxy)propyltrimethoxysilane, namely KH560, whose structural formula is:

.

In a preferred embodiment of the present invention, the preparation of phosphoric triamide uses a solvent or does not use a solvent; when using a solvent, the solvent is toluene.

In a preferred embodiment of the present invention, the reaction molar ratio of the phosphoric triamide to the epoxy coupling agent is 1:1-3:1.

The present invention also protects the phosphorus-containing aminated coupling agent prepared by the above preparation method.

The present invention also protects the application of the phosphorus-containing aminated coupling agent on the surface of carbon fibers, using the phosphorus-containing aminated coupling agent to prepare a sizing agent for flame-retardant modification of the carbon fiber surface, wherein the phosphorus-containing amino The volume fraction of coupling agent is 2~7%, and it is hydrolyzed with uniform stirring for 0.5~2h.

In a preferred embodiment of the present invention, the carbon fibers are obtained from polyacrylonitrile bases, and the final heat treatment temperature is within 1200-3000°C.

Compared with the prior art, the preparation process of the phosphorus-containing aminated coupling agent involved in the present invention is simple, the reaction is stable, and the surface sizing coating process is applied to the surface of carbon fiber, which can not only maintain the interfacial properties between carbon fiber and epoxy resin At the same time, the flame retardant performance of the carbon fiber epoxy resin composite material has been significantly enhanced, and the interface performance and flame retardant performance of the material have been satisfied.

Description of drawings

Do further description below in conjunction with accompanying drawing:

Fig. 1 is the FTIR spectrum of the phosphorus-containing aminated coupling agent obtained in Example 1.

Detailed ways

Below in conjunction with embodiment do further explanation.

In the following examples, two carbon fibers with different surface conditions are used, namely:

Carbon Fiber 1: Polyacrylonitrile-based carbon fiber with an epoxy-type sizing layer.

Carbon fiber 2: Polyacrylonitrile-based carbon fiber with high temperature degumming and no glue layer on the surface.

Effects of the invention The interlayer shear strength is used to evaluate the interfacial bonding performance of the material, and the flame retardant performance of the material is evaluated by the value of the limiting oxygen index. The results of the above two kinds of carbon fiber surface flame retardant modification are shown in Table 1.

Example 1

The reaction equation of the present embodiment is as follows:

Phosphoric triamide and KH560 were used as raw materials in the reaction process. In a 100ml three-necked flask, 19ml of phosphoric triamide was added. Under the protection of nitrogen, 22ml of KH560 was added dropwise, and the temperature was raised to 60°C while stirring. After 30 minutes of reaction, stop reaction. As shown in Figure 1, its structural characterization is as follows: FTIR (KBr) (cm ^-1 ): 3347 and 3297 (-NH ₂ ), 2940 and 2840 (-CH ₂ ), 1562 (-NH), 1201 (P=O ), 1083 (Si-O), 1056 (PCO).

The modified phosphorus-containing aminated coupling agent with this structure is used for flame-retardant treatment of carbon fiber surface. Carbon fiber 1 was treated by surface sizing, and the solution preparation method was as follows: 5ml of the above-mentioned modified phosphorus-containing aminated coupling agent was added dropwise to a mixed solution of 10ml of methanol and 85ml of water, and stirred evenly for 1 hour for hydrolysis. The fibers after surface treatment were compounded with epoxy 6101 resin, and triethylenetetramine was used as a curing agent to prepare interlaminar shear and limiting oxygen index test specimens. The test results are shown in Table 1.

Example 2

The type of fiber used in Example 1 was changed, carbon fiber 2 was adopted, and the rest of the treatment conditions were the same as in Example 1.

Comparative example 1

Carbon fiber 1 was composited with epoxy 6101 resin, and triethylenetetramine was used as a curing agent to prepare interlaminar shear and limiting oxygen index test specimens. The test results are shown in Table 1.

Comparative example 2

The proportion of the solution in Example 1 was changed, and 15ml of the modified phosphorus-containing aminated coupling agent was added dropwise to the mixed solution of 30ml of methanol and 55ml of water, and the solution was uniformly stirred and hydrolyzed for 1 hour. All the other processing conditions are with embodiment 1.

Table 1 Interlaminar shear strength and limiting oxygen index of composite materials

It can be seen from the results in Table 1 that the carbon fiber epoxy resin composite material prepared by satisfying the conditions of the present invention has both excellent interface performance and flame retardancy. However, carbon fiber epoxy resin composite materials that have not been modified with the above-mentioned phosphorous-containing aminated coupling agent, and whose modified parameters are outside the above-mentioned limited range, cannot simultaneously have excellent interface and flame-retardant properties.

The above embodiments show and describe the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the above-mentioned embodiments. The above-mentioned embodiments and descriptions only illustrate the principle of the present invention, rather than limit the scope of the present invention in any way, without departing from the scope of the present invention. Under the premise, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the claims.

Claims (8)

1. a kind of preparation method of phosphorous amination coupling agent characterized by comprising the phosphoric triamide is added to reactor It is interior, under nitrogen protection, slowly heats up, epoxy group coupling agent is added dropwise in reaction system, the stirring speed kept constant Degree reacts 30min ~ 1h between 40 ~ 60 DEG C.

2. preparation method according to claim 1, which is characterized in that the phosphoric triamide is existed by phosphate and ethylenediamine Under nitrogen protection, reacts 1-3 hours and be prepared under the boiling point of ethylenediamine.

3. preparation method according to claim 1, which is characterized in that the epoxy group coupling agent is γ-(2,3- rings Oxygen propoxyl group) propyl trimethoxy silicane, structural formula are as follows:

。

4. preparation method according to claim 2, which is characterized in that the preparation of phosphoric triamide is using solvent or does not use Solvent；When using solvent, solvent is toluene.

5. preparation method according to claim 1, which is characterized in that the phosphoric triamide is anti-with epoxy group coupling agent Answering molar ratio is 1:1 ~ 3:1.

6. the phosphorous amination coupling agent that preparation method according to any one of claims 1-5 is prepared.

7. application of the phosphorous amination coupling agent according to claim 6 on carbon fiber surface, which is characterized in that use institute The phosphorous amination coupling agent stated prepares the flame-retardant modified sizing agent of carbon fiber surface, wherein the phosphorous amination coupling agent Volume fraction be 2 ~ 7%, and uniform stirring hydrolyze 0.5 ~ 2h.

8. application according to claim 7, which is characterized in that the carbon fiber is using polyacrylonitrile-radical as raw material, most The carbon fiber that whole heat treatment temperature obtains in 1200-3000 DEG C.