TW201905090A - Carbon fiber composite material and method for preparing the same having higher mechanical properties and thermal stability than currently available carbon fiber composite material - Google Patents

Abstract

A carbon fiber composite material which comprises a modified carbon fiber substrate and a polyimide distributed on the modified carbon fiber substrate, wherein the modified carbon fiber substrate comprises carbon fibers and a modifier distributed on the carbon fibers, wherein the modifier is obtained by reacting an amine group-containing silane with an acid anhydride. The mechanical properties and thermal stability of the carbon fiber composite material of the present invention are higher than those of the currently available carbon fiber composite material.

Description

Carbon fiber composite material and preparation method thereof

The invention relates to a carbon fiber (CF) composite material and a preparation method thereof, in particular to a carbon fiber composite material comprising polyimide (PI) and a preparation method thereof.

Composite materials refer to materials obtained by composite processing of two or more materials with different properties. In recent years, composite materials based on carbon fiber substrates have been widely used in aviation, textile products, construction, and automobiles. Body structure, electronic parts and other fields. Such carbon fiber composites will also typically include a reinforcing agent distributed on the carbon fiber substrate to enhance various properties of the fibrous substrate, such as mechanical properties or thermal stability of the reinforcing fiber substrate.

Polyimine has high thermal stability and high glass transition temperature (T _g ), so it is often chosen as a reinforcing agent in carbon fiber composites. For example, the publication "Preparation of carbon fiber-reinforced polyimide composites via in situ induction heating" disclosed by High Performance Polymers in September 2016 discloses a carbon fiber composite material using polyimine as a reinforcing agent, which is a polyamine. A solution of methic acid (DMAc) of amide acid (PAA) is applied to a carbon fiber substrate, and the polyamine acid is subjected to an imidization reaction to form a polyfluorene by a hot pressing method. After the imine, the carbon fiber composite was produced. However, it has been found through experiments that the mechanical properties and thermal stability of the aforementioned carbon fiber composites need to be further improved.

Therefore, how to improve the mechanical properties and thermal stability of the existing carbon fiber composite materials containing polyimine, and to develop a carbon fiber composite material with high mechanical properties and high thermal stability has become the research direction.

Accordingly, a first object of the present invention is to provide a carbon fiber composite material having both high mechanical properties and high thermal stability.

Thus, the carbon fiber composite of the present invention comprises a modified carbon fiber substrate and a polyimine disposed on the modified carbon fiber substrate, wherein the modified carbon fiber substrate comprises carbon fibers and is modified on the carbon fibers. a granulating agent obtained by reacting an amino group-containing silane with an acid anhydride.

In addition, a second object of the present invention is to provide a method for preparing a carbon fiber composite according to the present invention, comprising the steps of: (1) disposing a modifier on carbon fibers to form a modified carbon fiber substrate, wherein the modification The granule is obtained by reacting an amine group-containing decane with an acid anhydride; (2) applying a poly phthalic acid solution to the modified carbon fiber substrate to obtain a prepreg; and (3) The carbon fiber composite material is obtained by hot pressing the prepreg and subjecting the polyamic acid to a ruthenium iodide reaction to form a polyimine.

The effect of the present invention is that the carbon fiber composite material of the present invention is mechanically and thermally stabilized by using a carbon fiber which has been modified by a modifier which has been obtained by reacting an amine group-containing decane with an acid anhydride. Sex will be higher than existing carbon fiber composites that use unmodified carbon fiber.

The contents of the present invention will be described in detail below:

[ Carbon fiber composite ]

Preferably, the modifier is obtained by reacting an amine group-containing decane with an acid anhydride in an organic solvent.

Preferably, the amine group-containing decane is represented by the formula (I): Si(R ¹ ) ₃ -X-NH ₂ (I) wherein R ¹ is OR ² , methyl or ethyl, and R ² is A Or ethyl, X is -Y- or -Y-NH-Y-, Y is methylene, C ₂ -C ₁₀ alkyl or phenyl.

More preferably, R ¹ of the formula (I) is OR ² or a methyl group, R ² is a methyl group or an ethyl group, and Y is a methylene group or a C ₂ -C ₃ alkylene group.

Still more preferably, the amine group-containing decane is selected from the group consisting of 3-aminopropyltrimethoxysilane (abbreviated as APTMOS) and 3-aminopropyltriethoxydecane [( 3-aminopropyl)triethoxysilane (APTEOS), 3-(2-aminoethylamino)propyldimethoxymethylsilane, (3-aminopropyl) 3-(ethoxydimethylsilyl) propylamine or a combination of the foregoing.

Preferably, the anhydride is a dianhydride. More preferably, the dianhydride is selected from the group consisting of bis(phthalic anhydride), bis(phthalic anhydride), and bicyclo [2.2.2] octane. -7-ene-2,3,5,6-tetracarboxylic dianhydride {bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, BCDA}, 3,3' , 4,4'-benzophenonetetracarboxylic dianhydride (3,3',4,4'-benzophenonetetracarboxylic dianhydride, BTDA for short), 4,4-(hexafluoroisopropene) diacetic anhydride [4,4' -(hexafluoroisopropylidene)diphthalic anhydride, referred to as 6FDA], 3,3',4,4'-biphenyltetracarboxylic dianhydride (3,3',4,4'- biphenyltetracarboxylic dianhydride, BPDA), 1,2, 4,5-cyclohexanetetracarboxylic dianhydride (HPDMA), 1,2,3,4-cyclobutanetetracarboxylic dianhydride (cyclobutane-1, 2, 3 4-tetracarboxylic dianhydride (CBDA for short) or a combination of the foregoing.

Preferably, the organic solvent is selected from a polar aprotic organic solvent or an alcohol. More preferably, the organic solvent is selected from the group consisting of dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethyl hydrazine (DMSO), methanol. , ethanol or a combination of the foregoing.

Preferably, the molar ratio of the amine-containing decane to the anhydride ranges from 2 to 3. More preferably, the molar ratio of the amine-containing decane to the anhydride ranges from 2 to 2.1.

Preferably, the polyimine contains a structure of the following formula (II): (II) wherein, Ar ¹ is one of the various structures listed in Table 1 below, and Ar ² is one of the various structures listed in Table 2 below, and n is 15 to 600.

table

Table 2

More preferably, Ar ¹ is , Ar ² is .

Preferably, the modifier has a weight ranging from 5 to 25 wt% based on 100 wt% of the total weight of the modified carbon fiber substrate. More preferably, the modifier has a weight ranging from 15 to 25 wt% based on 100 wt% of the total weight of the modified carbon fiber substrate.

[ Method for preparing carbon fiber composite material ]

a. step (1) :

Preferably, in the step (1), the modifier is obtained by reacting an amine group-containing decane with an acid anhydride in an organic solvent.

Preferably, in the step (1), the amine group-containing decane is the same as the above-mentioned [carbon fiber composite material] with respect to the amine group-containing decane, and the acid anhydride is the same as the above-mentioned [carbon fiber composite material] for the description of the acid anhydride. This organic solvent is the same as the description about the organic solvent in the aforementioned [carbon fiber composite material].

Preferably, in the step (1), a modification solution containing a modifier and an organic solvent is applied to the carbon fibers, followed by pre-curing. It should be particularly noted that the temperature during the pre-curing can be adjusted according to the selected organic solvent. For example, when the organic solvent is a polar aprotic organic solvent, it is pre-cured at 80 to 110 ° C, and the organic solvent is an alcohol. At the time, it is pre-cured at 20 to 35 °C.

More preferably, the modified solution has a solid content ranging from 10 to 50 wt%. Still more preferably, the modified solution has a solids content ranging from 15 to 25 wt%.

b. step (2) :

Preferably, in the step (2), the polyaminic acid solution is obtained by reacting a diamine and a dianhydride in an organic solvent.

More preferably, the dianhydride has the structure of the following formula (III): (III) wherein, Ar ¹ is one of the various structures listed in Table 1 above.

More preferably, the dianhydride is selected from the group consisting of 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), pyromellitic dianhydride (PMDA), bisphenol A diether dianhydride (IDPA) or a combination of the foregoing.

More preferably, the diamine has a structure of the following formula (IV): H ₂ N-Ar ² -NH ₂ (IV) wherein Ar ₂ is one of the various structures listed in Table 2 above.

Still more preferably, the diamine is selected from the group consisting of 4,4'-diaminodiphenyl ether (ODA) and 3,3'-diaminodiphenyl hydrazine (3,3). '-sulfonyldianiline, abbreviated as mDDS), 4,4'-(4,4'-isopropylidenediphenyl-1,1'-dioxy)diphenylamine [4,4'-(4,4'-isopropylidenediphenyl) - 1,1-diyldioxy)dianiline, abbreviated as BAPP], 1,3-bis(4-aminophenoxy)benzene [1,3-bis(4-aminophenoxy)benzene, abbreviated as pBAPB], 1,3-double (3-aminophenoxy)benzene, abbreviated as mBAPB, or a combination of the foregoing.

More preferably, the organic solvent is selected from the group consisting of dimethylacetamide (DMAc), N-methylpyrrolidone (NMP) or a combination of the foregoing.

More preferably, the polyamic acid contains a structure of the following formula (V): (V) wherein, Ar ¹ is one of the various structures listed in Table 1 above, and Ar ² is one of the various structures listed in Table 2 above, and n is 15 to 700.

Preferably, in the step (2), the polyamine acid solution has a solid content ranging from 10 to 45 wt%. More preferably, in the step (2), the polyamine acid solution has a solid content ranging from 25 to 45 wt%.

Preferably, in the step (2), after the poly-proline solution is applied to the modified carbon fiber substrate, the prepreg is formed in an environment of 80 to 110 ° C.

c. step (3) :

Preferably, in the step of hot pressing the prepreg, the step (3) is divided into a plurality of heating stages and sequentially heated, for example, into three heating stages, and the temperature in the first heating stage is capable of removing moisture. The temperature, the temperature in the second temperature rising stage is the boiling point temperature of the solvent of the polyaminic acid solution, and the temperature in the third temperature rising stage is a temperature at which the polyaminic acid can be completely imidized. More preferably, the temperature in the first temperature rising phase ranges from 95 to 105 ° C, the temperature in the second temperature rising phase ranges from 160 to 170 ° C, and the temperature in the third temperature rising phase ranges from 245 to 255 ° C. More preferably, the time range of the first temperature rising phase is 20 to 40 minutes, the time range of the second temperature rising phase is 20 to 40 minutes, and the time range of the third temperature rising phase is 50 to 70 minutes.

Preferably, in the step of hot pressing the prepreg, the step (3) is divided into a plurality of step-up stages and sequentially boosted, for example, into two step-up stages, and the pressure range of the first step-up stage. It is 20~30 kg/cm ² and the pressure in the second boosting stage is 45~55 kg/cm ² . More preferably, the first boosting phase has a time range of 80 to 100 min, and the second boosting phase has a time range of 20 to 40 min.

< Preparation example 1>

Preparing a modified solution containing a modifier and dimethyl acetamide

The modified solution of Preparation Example 1 was prepared according to the amount of each component used in Table 3 below and the following method:

table 3

After mixing 3-aminopropyltriethoxydecane (APTEOS), bisphenol A diether dianhydride (IDPA) and dimethylacetamide (DMAc) and stirring, the modified modifier is prepared. A modified solution of dimethyl acetamide (solid content: 20 wt%).

< Preparation example 2>

Preparation of polyaminic acid solution

The polyaminic acid solution of Preparation Example 2 was prepared according to the amount of each component used in Table 4 below and the following procedure:

Table 4

Step (1) : Mixing 3,3'-diaminodiphenylguanidine (mDDS) with dimethylacetamide (DMAc) and stirring until completely dissolved, a mixed solution is obtained.

Step (2) : adding 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) to the mixed solution in portions, and after completion of the reaction, preparing the polyaminic acid solution ( The solid content is 40 wt%).

< Example 1>

Preparation of carbon fiber composite ( Modified CF/PI)

The carbon fiber composite of Example 1 was prepared according to the following steps:

Step (1) : coating the modified solution containing the modifier and dimethylacetamide obtained in Preparation Example 1 (solid content: 20 wt%) on carbon fiber (10 cm × 10 cm) to impregnate the carbon fiber After completion, it is pre-cured in an oven at 80-110 ° C to form a modified carbon fiber substrate, wherein the content of the modifier is 100 wt% of the total weight of the modified carbon fiber substrate. It is 20 wt%.

Step (2) : After coating the polyaminic acid solution (solid content: 40 wt%) obtained in Preparation Example 2 on the modified carbon fiber substrate, a prepreg was formed at 80 to 110 ° C.

Step (3) : hot pressing the prepreg with a hot press preheated to 100 ° C to carry out the hydrazine imidization reaction in the prepreg to form a polyamidimide, and then lowering to a normal temperature. That is, the carbon fiber composite material of Example 1 was obtained. It should be specially noted that in the process of hot pressing the prepreg, a total of three temperature rising stages and two pressure rising stages are sequentially performed for temperature rising and boosting, and the temperature rising and boosting conditions of each stage are as follows: Shown.

table 5

< Comparative example 1>

Preparation of carbon fiber composite ( Not modified CF/PI)

The carbon fiber composite of Comparative Example 1 was prepared according to the following steps:

Step (1) : coating the polyaminic acid solution (solid content: 40 wt%) obtained in Preparation Example 2 on carbon fiber (10 cm × 10 cm), and then forming a prepreg at 80 to 110 ° C. .

Step (2) : hot pressing the prepreg with a hot press preheated to 100 ° C to carry out the hydrazine imidization reaction in the prepreg to form a polyimide, and then lower to a normal temperature. That is, the carbon fiber composite material of Comparative Example 1 was obtained. It should be specially noted that in the process of hot pressing the prepreg, a total of three heating stages and two stepping stages are sequentially performed for heating and boosting, and the temperature rising and boosting conditions of each stage are as shown in Table 5 above. Shown.

< Unmodified carbon fiber With modified carbon fiber SEM Photo analysis >

The modified carbon fiber substrate obtained by the step (1) of the first embodiment and the unmodified carbon fiber were respectively photographed by a scanning electron microscope (SEM), and the obtained SEM photograph is shown in FIG. 1 to 2. Shown. 1 is a SEM photograph of an unmodified carbon fiber, and FIG. 2 is a SEM photograph of a modified carbon fiber substrate of the step (1) of Example 1.

Comparing the SEM photographs of Figs. 1 to 2, it can be found that the appearance of the modified carbon fiber substrate obtained in the step (1) of the first embodiment is different from that of the generally unmodified carbon fiber, and it is proved that the step (1) of the embodiment 1 has indeed distributed the modifier. A modified carbon fiber substrate is formed on the carbon fibers.

< Analysis of Mechanical Properties and Thermal Stability of Carbon Fiber Composites >

testing method

a. Storage modulus (storage modulus) :

The analysis was carried out for Example 1 and Comparative Example 1 using a dynamic mechanical analyzer (TA DMA 2980) and according to the ASTM D738 standard method. 3 is a graph showing the relationship between the storage modulus (MPa) and the temperature (° C.) measured by the carbon fiber composite materials of Example 1 and Comparative Example 1, and the carbon fiber composite materials of Example 1 and Comparative Example 1 were 50. The storage modulus at °C is summarized in Table 7 below.

b. tensile strength (tensile strength) Tensile modulus (tensile modulus) :

Tensile strength and tensile modulus analysis were performed for Example 1 and Comparative Example 1, respectively, according to the ASTM D3039 standard method. The tensile strength and the tensile modulus of the carbon fiber composite materials of Example 1 and Comparative Example 1 were respectively summarized in Table 7 below.

c. Bending strength (flexural strength) And bending modulus (flexural modulus) :

The flexural strength and flexural modulus analysis were performed for Example 1 and Comparative Example 1 according to the ASTM D790 standard method. The flexural strength and the flexural modulus of the carbon fiber composite materials of Example 1 and Comparative Example 1 were respectively summarized in Table 7 below.

d. Glass transition temperature (T _g ) :

The analysis was carried out for Example 1 and Comparative Example 1 using a dynamic mechanical analyzer (TA DMA 2980) and according to the ASTM D738 standard method. 4 is a graph showing the relationship between tan (δ) and temperature (° C.) measured by the carbon fiber composite materials of Example 1 and Comparative Example 1, and the carbon fiber composite materials of Example 1 and Comparative Example 1 were tan (δ). The temperature at the maximum (i.e., T _g ) is summarized in Table 7 below.

e. Thermogravimetric loss temperature (T _95% ) :

The analysis was carried out for Example 1 and Comparative Example 1 using a thermogravimetric analyzer (TA TGA Q500) and according to the specifications of ASTM E1528. 5 is a graph showing the relationship between the weight (wt%) and the temperature (° C.) measured by the carbon fiber composite materials of Example 1 and Comparative Example 1, and the carbon fiber composite materials of Example 1 and Comparative Example 1 were subjected to weight loss. The temperature at 5 wt% (i.e., T _95% ) is summarized in Table 7 below.

f. Flame resistance (UL-94V Class fire test ) :

The carbon fiber composite materials of Example 1 and Comparative Example 1 were respectively ignited and the ability to extinguish them was observed. Among them, UL-94V class fire test rating is shown in Table 6 below, and the results of Example 1 and Comparative Example 1 are summarized in Table 7 below.

Table 6

Table 7

Results and discussion

From the data of storage modulus, tensile strength, tensile modulus, flexural strength and flexural modulus of Table 7, the storage modulus, tensile strength, tensile modulus, and flexural strength of Example 1 were found. The flexural modulus is greater than that of Comparative Example 1, that is, the mechanical properties of Example 1 are greater than that of Comparative Example 1, indicating that the present invention utilizes a carbon fiber modified by a modifier (obtained by reacting an amine-containing decane with an acid anhydride). In the carbon fiber composite material (Example 1), the carbon fiber composite material of the present invention has high mechanical properties as compared with the conventional carbon fiber composite material using the unmodified carbon fiber (Comparative Example 1).

From the glass transition temperature (T _g ) and the thermogravimetric loss (T _95% ) data of Table 7, it can be found that the T _g and T _{95% of} Example 1 are also larger than the T _g and T _{95% of} Comparative Example 1, It is shown that the thermal stability of Example 1 is greater than that of Comparative Example 1, and the carbon fiber composite material prepared by modifying the carbon fiber via a modifier (obtained by reacting an amine group-containing decane with an acid anhydride) is also demonstrated. In Example 1), the carbon fiber composite of the present invention has higher thermal stability than the conventional carbon fiber composite material using the unmodified carbon fiber (Comparative Example 1).

Further, as is clear from the UL-94 grade data of Table 7, both Example 1 and Comparative Example 1 are V-0 grades, and the carbon fiber composite material of the present invention has the same flame resistance as the conventional carbon fiber composite.

In summary, the carbon fiber composite material of the present invention is modified by the use of a modifier which has been modified by an amine group-containing decane and an acid anhydride, so that the mechanical properties and thermal stability of the carbon fiber composite material of the present invention are It is higher than the conventional carbon fiber composite material using unmodified carbon fiber, and thus the object of the present invention can be achieved.

However, the above is only the embodiment of the present invention, and the scope of the invention is not limited thereto, and all the simple equivalent changes and modifications according to the scope of the patent application and the patent specification of the present invention are still Within the scope of the invention patent.

Other features and effects of the present invention will be apparent from the following description of the drawings, wherein: FIG. 1 is a SEM photograph illustrating unmodified carbon fibers; FIG. 2 is an SEM photograph illustrating the steps of Example 1. (1) The modified carbon fiber substrate; Fig. 3 is a graph showing the relationship between the storage modulus (MPa) and the temperature (°C) of the carbon fiber composite materials of Example 1 and Comparative Example 1; FIG. 5 is a graph showing the relationship between tan (δ) and temperature (° C.) of the carbon fiber composite material of Example 1 and Comparative Example 1; and FIG. 5 is a graph illustrating the weight of the carbon fiber composite material of Example 1 and Comparative Example 1 ( The relationship between wt%) and temperature (°C).

Claims (10)

A carbon fiber composite material comprising a modified carbon fiber substrate and a polyimide pigment distributed on the modified carbon fiber substrate, wherein the modified carbon fiber substrate comprises carbon fibers and a modifier disposed on the carbon fibers The modifier is obtained by reacting an amine group-containing decane with an acid anhydride. The carbon fiber composite material according to claim 1, wherein the amine group-containing decane is represented by the formula (I): Si(R ¹ ) ₃ -X-NH ₂ (I) wherein R ¹ is OR ² , A Or ethyl, R ² is methyl or ethyl, X is -Y- or -Y-NH-Y-, Y is methylene, C ₂ -C ₁₀ alkyl or phenyl. The carbon fiber composite material according to claim 1, wherein the acid anhydride is a dianhydride. A method for preparing a carbon fiber composite material comprises the following steps: (1) dispersing a modifier on carbon fibers to form a modified carbon fiber substrate, wherein the modifier is reacted with an amine group-containing decane and an acid anhydride. (2) applying a polyaminic acid solution to the modified carbon fiber substrate to obtain a prepreg; and (3) hot pressing the prepreg to carry the polyaminic acid on the imide After the reaction to form a polyimine, the carbon fiber composite is obtained. The method for producing a carbon fiber composite according to claim 4, wherein in the step (1), the amine group-containing decane is represented by the formula (I) in the claim 2. The method for producing a carbon fiber composite according to claim 4, wherein in the step (1), the acid anhydride is a dianhydride. The method for producing a carbon fiber composite according to claim 4, wherein the step (1) is pre-curing after applying a modified solution containing a modifier and an organic solvent to the carbon fibers. The method for producing a carbon fiber composite according to claim 4, wherein in the step (2), the solid content of the polyamic acid solution ranges from 10 to 45 wt%. The method for preparing a carbon fiber composite material according to claim 4, wherein in the step of hot pressing the prepreg, the temperature is sequentially increased into three heating stages, and the temperature in the first heating stage is energy. The temperature at which the water is removed, the temperature in the second temperature rising stage is the boiling point temperature of the solvent of the polyaminic acid solution, and the temperature in the third temperature rising stage is a temperature at which the polyaminic acid can be completely imidized. The method for preparing a carbon fiber composite material according to claim 4, wherein the step (3) is performed in the process of hot pressing the prepreg, and is sequentially divided into two pressure increasing stages, and the first step of boosting is performed. The pressure range is 20~30 kg/cm ² , and the pressure in the second boosting stage ranges from 45 to 55 kg/cm ² .