KR20100124623A - High dielectric polyimide-polyaniline composites and its preparation - Google Patents

Abstract

PURPOSE: A polyimide-polyaniline composite and a manufacturing method thereof are provided to secure the excellent high permittivity property and insulation property by the uniform morphology. CONSTITUTION: A manufacturing method of a polyimide-polyaniline composite comprises the following steps: adding polyaniline when polymerizing polyamic acid using acid dianhydride and diamine as monomers and termination reacting the mixture to form a polyaniline-polyelectrolyte solution; and heat-drying the polyaniline-polyelectrolyte solution. The termination reacting step is performed for 12~30 hours.

Description

High dielectric polyimide-polyaniline composites and its preparation

The present invention relates to a high dielectric polyimide-polyaniline complex and a method for preparing the same.

In general, a method of complexing a ceramic material or a metal material with a polymer material and using it as a high dielectric material is used.

Some examples of conventional methods for producing a high dielectric material can be given. As a first method, there is a method of using a ceramic, which has been widely used as an electromagnetic material because of its large capacitance and excellent insulation properties. However, such ceramic materials have limitations for use as ceramic materials alone because of the high temperature manufacturing process and the low mechanical strength. In addition, polymer materials have good workability but low dielectric constant. Therefore, a method of using a ceramic / polymer composite combining the advantages of these ceramic materials and polymer materials may be mentioned. As a second method, there is a method of increasing the dielectric constant by including a conductive metal material in the insulating layer. Metal materials can also express high dielectric properties by taking advantage of each other by complexing with polymers such as ceramic materials. The trend of high dielectric materials, which has been announced so far, has been mainly focused on incorporating ceramic or metal materials into organic polymers having excellent processability. However, these composite materials have a number of disadvantages. When added at a high ratio, the surface roughness of the film is increased due to aggregation and non-uniform phase formation, and the physical properties are also reduced. As a solution to this problem, several studies have been published. Instead of ceramics and metals, the results of using conductive polymers or organic compounds having a nucleophilic structure have recently been published. However, in the simple complexation of the conductive metal particles, the conductive polymer and the polymer matrix, the conductivity of the composite increases rapidly as the content of the added metal particles and the conductive polymer is increased to obtain high dielectric properties. It can be said that there is a limit.

Therefore, the inventors of the present invention have made an effort to prepare a composite with polyaniline using a polyaniline, which is an easy-to-manufacturing, economical conductive polymer having excellent economical efficiency, and a polyimide having excellent stability at high temperature as a matrix. In the step of forming the nanoparticles of polyaniline in the solution by electrostatic interaction of polyanimic acid and polyaniline precursors, polyaniline spherical particles of uniform size and morphology can be distributed without aggregation in the polyimide matrix. The present invention was completed by developing a polyimide-polyaniline composite having excellent high dielectric and insulating properties.

Therefore, in the present invention, the polyaniline nanoparticles are formed while the polyaniline solution is added in the polyamic acid polymerization step of growing an appropriate molecular weight in the step of polymerizing the polyamic acid using the acid dianhydride and the diamine as a monomer and the solution casting step is followed by imidization. To provide a polyimide-polyaniline composite having a high dielectric property and insulation and a method for producing the same.

The present invention

A step of preparing a polyaniline-polyamic acid solution by adding a polyaniline in a reaction of polymerizing a polyamic acid using an acid dianhydride and a diamine as a monomer and then terminating the polymerization reaction; And

Step 2 by heating and drying the solution of step 1

Characterized in that the method for producing a polyimide-polyaniline complex comprising a.

In addition, the present invention is another feature of the high dielectric polyimide-polyaniline complex prepared by the above method.

When the polyimide-polyaniline composite is prepared by the production method according to the present invention, polyaniline particles distributed in the polyimide matrix can be obtained in a uniformly distributed form with a spherical size of 100 nm or less. In the production method of the present invention, polyaniline produced by mass production can be used economically in a simple manner without being affected by the morphology and dispersion state of the polyaniline to be used, and all of the homogeneous morphology and size can be used in the matrix without affecting the initial state of polyaniline. Dispersion is possible. The formation of the polyaniline composite of the highly dispersed homogeneous morphology plays an important role in securing the excellent insulating properties of the polyimide-polyaniline composite, which gives the effect of maintaining the insulating properties even if the polyaniline component ratio is increased for the high dielectric properties. Can be utilized.

Hereinafter, the present invention will be described in more detail.

The present invention provides a polyimide having high dielectric properties by preparing a composite with polyimide, which is an insulator, and uniformly controlling the shape of polyaniline during film production, within the limit of the sharp increase in conductivity as the concentration of polyaniline increases. It relates to a polyaniline complex and a method for preparing the same.

The polyaniline doped as the conductive polymer used in the present invention can be used regardless of the morphology of the polyaniline formed by the general manufacturing method, and the weight average molecular weight is 2,000 ~ 200,000, the conductivity is 2 S / cm or more (2 ~ 200 S / cm) is used, and dodecylbenzenesulfonic acid (DBSA) doped for the improvement of solubility or thermal properties is most suitable. Polyaniline is dispersed in N, N-dimethylacetamide (DMAc) solvent for introduction into the polyamic acid production process.

The polyaniline dispersed in the solvent is added to the polyamic acid polymerization step. Acid dianhydrides and diamine monomers used in the production of polyamic acid are conventionally used in the production of polyimides, and are not particularly limited, but specifically pyromellitic dianhydride, 1,2,3,4-benzene tetracarboxylic dianhydride, benzo Phenone tetracarboxylic dianhydride, bis (dicarboxyphenylether) dianhydride, bis (dicarboxyphenylsulfone) dianhydride, bis (dicarboxyphenylsulfide) dianhydride, bis (dicarboxyphenyl) propane dianhydride, bis (dicarboxy) Phenyl) hexafluoropropane dianhydride, biphenyl tetracarboxylic dianhydride, naphthalene tetracarboxylic dianhydride, fluorine-substituted derivatives and alkyl-substituted derivatives thereof and the like can be used alone or in a mixture of two or more thereof. Acid dianhydrides linked by aliphatic carbon skeletons are generally used in the art, and specifically, may be used in the form of cyclobutane tetracarboxylic dianhydride alone or in a mixture of two or more thereof. As the diamine, aromatic and aliphatic diamines may be used as the diamine. Specifically, 4,4-oxyphenylenediamine, p -phenylenediamine, 4,4'-biphenyldiamine, 3,3'-oxydibenzeneamine , 3,4'-oxydibenzeneamine, 4,4'-oxydibenzeneamine, 3,3 '-(1,3-phenylenebis (oxy)) dibenzeneamine, 3,3'-(1, 4-phenylenebis (oxy)) dibenzeneamine, 4,4 '-(1,4-phenylenebis (oxy)) dibenzeneamine, 4,4'-(4,4'-sulfonylbis (4 , 1-phenylene) bis (oxy)) dibenzeneamine, 2,2-bis (4- (4-aminophenoxy) phenyl) propane, 2,2-bis (4- (4-aminophenoxy) phenyl Hexafluoropropane and its fluorine-substituted derivatives and alkyl-substituted derivatives alone or mixtures of two or more thereof may be used.

The reaction of the acid dianhydride and diamine is carried out under a solvent capable of dissolving these reactants and the prepared amic acid compound. The solvent is not particularly limited in the sugar field, but specifically N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, cresol, pyridine, dimethyl sulfoxide, γ-butyrolactone and the like and a mixed solvent thereof can be used.

The time point at which the polyaniline-dispersed solution is introduced into the polyamic acid polymerization step of the monomer is an important factor influencing the morphology and properties of the final polyaniline-polyimide composite. The dosing period is introduced from the start of polymerization and mixed in the monomeric acid dianhydride and diamine to form polyamic acid (method 1) and after the reaction, in the range of 10 to 20 minutes, i.e., polyamic acid in the form of oligomer, weight average molecular weight 3000 When the polyamic acid in the range of ~ 6000 is formed (method 2) and when the polyamic acid is formed of a polymer having a weight average molecular weight of 20000 or more can be determined by dividing. In the present invention, the polyaniline dispersion (method 2) in the step of forming the polyamic acid (weight average molecular weight 3000 ~ 6000) in the form of oligomer is selected and used as a suitable process for preparing a polyaniline-polyimide composite excellent. It is observed that the polyaniline dispersed according to the input time of each method shows interaction with the polyamic acid in different aspects. The polyamic acid formed in the polymerization reaction has carboxylic acid in the polymer main chain as a substituent for each repeating unit of the polymer chain, and they may be attached to the polyaniline polymer chain by electrostatic interaction, and in particular, may act as a dopant as an acid. This interaction between the polyamic acid and the polyaniline causes an increase in the dispersibility of the agglomerated polyaniline polymer particles in the solution and deformation of the morphology. In particular, this effect of the polyamic acid is hardly seen when the weight average molecular weight is greater than 20,000 (method 3), so there is no improvement in dispersibility of the polyaniline or modification of the morphology, and it is less effective when the polyaniline is introduced from the start of polymerization. Large amounts of aggregated particles remain (Method 1). In the state in which the polyamic acid grows into the oligomer, the dispersibility of the injected polyaniline is increased and morphological transformation into spherical nanoparticles is induced.

After the polyaniline solution was added to the polyamic acid polymerization solution, after 12 to 30 hours at 15-25 ° C. after the polymerization was completed, the solution was cast on a glass substrate and dried under heat to proceed with imidization of the polyamic acid. In this step, general polyimide casting conditions may be applied, but heat drying is performed at a temperature not exceeding 250 ° C. to prevent a change in the doping state of the polyaniline and a decrease in conductivity. Specifically, the solvent is removed while proceeding imidization through sequential heating at 80 to 100 ° C. for 1 to 3 hours, 110 to 130 ° C. for 1 to 3 hours, and 230 to 250 ° C. for 0.5 to 2 hours. In this process, the polyaniline, which interacts with the polyamic acid and is dispersed, is formed into spherical particles having a size of 100 to 200 nm while being phase-separated with the production of polyimide, and uniformly distributed in the polyimide matrix to form a complex.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the present invention is not limited by the following examples.

Example 1

A mechanical stirring apparatus was installed in a three-necked flask, and 4,4-oxyphenylenediamine (2 g, 10 mmole) was dissolved in 20 mL of DMAc in a nitrogen atmosphere, and then cooled to 0 ° C in a completely dissolved state. Pyromellitic dianhydride (2.18 g, 10 mmole) and 10 mL of DMAc were added dropwise. After the reaction proceeds for about 10 minutes at low temperature (0 ° C.) (after the polyamic acid having a weight average molecular weight of 5000 is formed), when the viscosity of the mixed solution gradually increases, the DBSA-doped weight average molecular weight is 40000, and the conductivity Polyaniline (420 mg, 10 wt%) having a 1.2 S / cm was dissolved in 10 mL of DMAc, and added dropwise to the reaction solution at once. The mixed solution was reacted at room temperature (20 ° C.) for 18 hours to terminate the polymerization. The polyimide / polyaniline complex solution thus prepared was applied to a glass substrate and treated in an oven under nitrogen atmosphere at 90 ° C. for 2 hours, 120 ° C. for 2 hours, and 250 ° C. for 1 hour to prepare a polyimide-polyaniline complex [FIG. 1].

As shown in Figure 1, it can be seen that the polyaniline nanoparticles of spherical uniform size (80 ~ 100 nm) and morphology is very uniformly dispersed and distributed in the polyimide matrix.

Example 2

A mechanical stirring apparatus was installed in a three-necked flask, and 4,4-oxyphenylenediamine (2 g, 10 mmole) was dissolved in 20 mL of DMAc in a nitrogen atmosphere, and then cooled to 0 ° C. in a completely dissolved state. Pyromellitic dianhydride (2.18 g, 10 mmole) and 10 mL of DMAc were added dropwise. After the reaction proceeds for about 10 minutes at low temperature (0 ° C.) (after the polyamic acid having a weight average molecular weight of 5000 is formed), when the viscosity of the mixed solution gradually increases, the DBSA-doped weight average molecular weight is 40000, and the conductivity Polyaniline (252 mg, 6 wt%) having a ratio of 1.2 S / cm was dissolved in 10 mL of DMAc, and added dropwise to the reaction solution at once. The mixed solution was reacted at room temperature (20 ° C.) for 18 hours. The polyimide / polyaniline complex solution thus prepared was applied to a glass substrate and treated in an oven under nitrogen atmosphere at 90 ° C. for 2 hours, 120 ° C. for 2 hours, and 250 ° C. for 1 hour to prepare a polyimide-polyaniline complex [FIG. 2].

As shown in Figure 2, it can be seen that the polyaniline nanoparticles of spherical size (30 ~ 100 nm) and the form is uniformly dispersed in the polyimide matrix.

Comparative Example 1

A mechanical stirring apparatus was installed in a three-necked flask, and 4,4-oxyphenylenediamine (2 g, 10 mmole) was dissolved in 20 mL of DMAc in a nitrogen atmosphere, and then cooled to 0 ° C. in a completely dissolved state. Polyaniline (420 mg, 10 wt%) having a DBSA-doped weight average molecular weight of 40000 and a conductivity of 1.2 S / cm was dissolved in 10 mL of DMAc, and then added dropwise to the reaction solution. Pyromellitic dianhydride (2.18 g, 10 mmole) and 10 mL of DMAc were added dropwise. After the reaction was performed at a low temperature (0 ° C.) for about 10 minutes, the mixed solution was terminated at room temperature (20 ° C.) for 18 hours. The polyimide / polyaniline complex solution thus prepared was applied to a glass substrate and treated in an oven under nitrogen atmosphere at 90 ° C. for 2 hours, 120 ° C. for 2 hours, and 250 ° C. for 1 hour to prepare a polyimide-polyaniline complex [FIG. 3].

As shown in FIG. 3, the formation of polyaniline particles was observed, but it was observed that these agglomerations formed in the polyimide membrane.

Comparative Example 2

A mechanical stirring apparatus was installed in a three-necked flask, and 4,4-oxyphenylenediamine (2 g, 10 mmole) was dissolved in 20 mL of DMAc in a nitrogen atmosphere, and then cooled to 0 ° C. in a completely dissolved state. Pyromellitic dianhydride (2.18 g, 10 mmole) and 10 mL of DMAc were added dropwise. After terminating the polymerization reaction at room temperature (20 ° C.) for 18 hours, polyaniline (420 mg, 10 wt%) having a DBSA-doped weight average molecular weight of 40000 and a conductivity of 1.2 S / cm was added to DMAc 10. After dissolving in mL, the reaction solution was added dropwise at once. The polyimide / polyaniline complex solution thus prepared was applied to a glass substrate and treated in an oven under nitrogen atmosphere at 90 ° C. for 2 hours, 120 ° C. for 2 hours, and 250 ° C. for 1 hour to prepare a polyimide-polyaniline complex [FIG. 4].

As shown in FIG. 4, it was observed that the polyaniline was not present as individual particles on the polyimide matrix but aggregated and aggregated.

Comparative Example 3

A mechanical stirring apparatus was installed in a three-necked flask, and the reaction was carried out in a reaction of oxydibenzeneamine-4,4-oxyphenylenediamine with bis (dicarboxyphenyl) hexafluoropropane dianhydride having a weight average molecular weight of 25000 in a nitrogen atmosphere. After dissolving 4.2 g of polyimide in 20 mL of DMAc, polyaniline (420 mg, 10wt%) having a weight average molecular weight of 40000 doped with DBSA and 1.2 S / cm conductivity was dissolved in 10 mL of DMAc, and then added dropwise thereto for 1 hour. Stirred. The polyimide / polyaniline complex solution thus prepared was applied to a glass substrate and treated in an oven under nitrogen atmosphere at 90 ° C. for 2 hours, 120 ° C. for 2 hours, and 250 ° C. for 1 hour to prepare a polyimide-polyaniline complex.

Comparative Example 4

Prepared in the same manner as in Comparative Example 3, but the amount of polyaniline added to 252 mg, 6 wt% to prepare a composite.

Comparative Example 5

6.0 g of an average particle diameter of 1.2 μm 4,4-oxyphenylenediamine-pyromellitic dianhydride polyimide powder and 600 mg of polyaniline powder having a weight average molecular weight of 40000 and a conductivity of 1.2 S / cm are doped with DBSA. Put in a mixer and mixed for 1 hour. The mixed powder was filled into a press of 7 mm diameter mold and pressed to 8 ton to obtain pellets of 7 mm diameter and 600 μm thickness.

Experimental Example 1

In order to confirm the dielectric properties of the polyimide-polyaniline complexes prepared in Examples 1 to 2 and Comparative Examples 1 to 5, the following experiment was performed.

In Examples 1 to 2 and Comparative Examples 1 to 4, a thin film having a line width of 2.9 mm and a thickness of 5 to 10 μm was formed on a glass substrate coated with an ITO electrode, and a gold electrode having a line width of 2.1 mm was deposited on the thin film. Dielectric and insulating properties were measured and shown in Table 1 below. In Comparative Example 5, gold electrodes were coated on both surfaces of the prepared pellet sample to measure dielectric properties and insulation properties.

[How to measure]

1) Dielectric constant: The relative dielectric constant and capacitance density were measured using the Agilent 4294A Precision Impedance Analyzer on the thin film capacitor fabricated by the method described above.

2) Electrical Conductivity: Measured using a Keithley 2410 source meter.

division Polyaniline Content (wt%) Dielectric constant Electrical conductivity
(S / cm) Example 1 10 37 1.3 x 10 ^-5 Example 2 6 12 6.6 x 10 ^-6 Comparative Example 1 10 21 8.9 x 10 ^-5 Comparative Example 2 10 16 1.2 x 10 ^-4 Comparative Example 3 10 22 7.5 x 10 ^-4 Comparative Example 4 6 5 7.9 x 10 ^-6 Comparative Example 5 10 6 9.2 x 10 ^-4

As shown in Table 1, as a result of confirming the dielectric properties of the thin film between the electrodes obtained through Example 1 can be confirmed excellent results in the dielectric constant and insulation.

This property can be attributed to the state of the polyaniline forming the spherical 100 nm nanoparticles and the complex in which they are dispersed very uniformly, as observed in FIG. In particular, even when the polyaniline is added in order to increase the low dielectric constant value, the increase in conductivity is shown to be small, indicating that the polyaniline particles are insulated from each other without forming an electrically conductive channel in the matrix. This characteristic becomes clearer when compared with the conductivity values measured in Comparative Examples 2, 3 and 5. That is, in Comparative Examples 2, 3, and 5, the dielectric properties were also low, but relatively high conductivity appeared, resulting in a decrease in insulation performance. In other words, it can be seen that the polyaniline particle formation in the state of interacting with the polyamic acid of the oligomer stage in the manufacturing process by the method proposed in the present invention plays an important role in forming the excellent dielectric film.

Comparing the results of Example 2 and Comparative Example 4 it can be seen that even in the same 6 wt% polyaniline content, the composite formation method of the present invention shows a high dielectric constant.

1 shows an electron micrograph of the polyaniline-polyimide complex formation of Example 1. FIG.

Figure 2 shows an electron micrograph of the polyaniline-polyimide complex formation of Example 2.

Figure 3 shows an electron micrograph of the polyaniline-polyimide complex formation of Comparative Example 1.

Figure 4 shows an electron micrograph of the polyaniline-polyimide complex formation of Comparative Example 2.

Claims (7)

A step of preparing a polyaniline-polyamic acid solution by adding a polyaniline in a reaction of polymerizing a polyamic acid using an acid dianhydride and a diamine as a monomer and then terminating the polymerization reaction; And Step 2 by heating and drying the step 1 polyaniline-polyamic acid solution Method for producing a polyimide-polyaniline complex comprising a. According to claim 1, wherein the acid dianhydride is pyromellitic dianhydride, 1,2,3,4-benzene tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, bis (dicarboxyphenyl ether) dianhydride, bis ( Dicarboxyphenylsulfone) dianhydride, bis (dicarboxyphenylsulfide) dianhydride, bis (dicarboxyphenyl) propane dianhydride, bis (dicarboxyphenyl) hexafluoropropane dianhydride, biphenyl tetracarboxylic dianhydride, naphthalene tetracarboxylic acid It is at least one selected from dianhydride and cyclobutane tetracarboxylic dianhydride. The method of claim 1, wherein the diamine is p -phenylenediamine, 4,4'-biphenyldiamine, 3,3'-oxydibenzeneamine, 3,4'-oxydibenzeneamine, 4,4'-jade Cydibenzeneamine, 3,3 '-(1,3-phenylenebis (oxy)) dibenzeneamine, 3,3'-(1,4-phenylenebis (oxy)) dibenzeneamine, 4,4 ' -(1,4-phenylenebis (oxy)) dibenzeneamine, 4,4 '-(4,4'-sulfonylbis (4,1-phenylene) bis (oxy)) dibenzeneamine, 2, And at least one selected from 2-bis (4- (4-aminophenoxy) phenyl) propane and 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane. The method of claim 1, wherein the polymerization termination reaction is performed at 15 to 25 ° C. for 12 to 30 hours. The method according to claim 1, wherein the polyaniline is added at a time when the weight average molecular weight of the polyamic acid to be polymerized corresponds to 3,000 to 6,000. The method according to claim 1, wherein the polyaniline has a weight average molecular weight of 2,000 to 200,000 and a conductivity of 2 S / cm or more. A high dielectric polyimide-polyaniline complex prepared by the method of any one of claims 1 to 6.

Images