KR100490882B1 - Synthetic Method of Polyaniline and application for electroststic discharge and EMI Shielding - Google Patents

Abstract

The present invention relates to a method for synthesizing polyaniline, which is a kind of conductive polymer used for reducing harmful effects on products and human body by electrostatic and electromagnetic waves generated in electronic components, and more specifically, to synthesis of polyaniline in solution state. It relates to a method and its application.

The polyaniline synthesis method of the present invention comprises the steps of dissolving 0.8-2.0 molar ratio of dopant in an organic solvent with respect to aniline monomer and aniline monomer, dissolving 0.4-2.0 molar ratio of oxidizing agent in water with aniline monomer, and aniline monomer And reacting the organic solvent in which the dopant is dissolved and the water in which the oxidant is dissolved at 0˜10 ° C., separating the solution in which the polyaniline is dissolved, and then washing with 2-5 times the washing solvent of the solution in which the polyaniline is dissolved. Steps.

Description

Synthetic Method of Polyaniline and application for electroststic discharge and EMI Shielding

The present invention relates to a method for synthesizing polyaniline, which is a kind of conductive polymer used for reducing harmful effects on products and human body by electrostatic and electromagnetic waves generated in electronic components, and more specifically, to synthesis of polyaniline in solution state. It relates to a method and its application.

Conventional general synthesis of polyaniline, a conductive polymer, dissolves aniline monomers and oxidants in a solvent and reacts them at a temperature below room temperature, usually 0 ° C, and then removes the hydrochloric acid groups that acted as catalysts after the solids were filtered, washed and dried. Since polyaniline is known to exhibit the highest conductivity when it is in an intermediate oxidation state, it is subjected to oxidation and neutralization using strong acids and strong bases to make the oxidation state into an intermediate oxidation type of about 0.5. For each reaction, solid aniline is dispersed in water, treated, and filtered to remove water and residual water and then dispersed in water to proceed to the next step. At this time, the time required for the filter and drying of the three or four times is more than 60 hours, and it takes 80 hours only to obtain undoped polyaniline. The solid polyaniline thus obtained must be dissolved using ultrasonic waves to be used as a solution after the doping process. In addition, when the dopant is in solution, doping with the polyaniline, which is a solid component, is very difficult, and the doping is performed by accurate calculation during the doping process. The extra dopant affects the overall physical properties of the conductive polymer polyaniline. For example, when dodecyl benzene sulfonic acid (DBSA) is doped into polyaniline obtained in a solid state, an extra dopant remains sticky and it is very difficult to match the exact amount. In addition, it has a cumbersome process of filtering the undissolved solids using a micro filter after the additional doping and dissolution process when dissolved in the ultrasonic bath after doping to dissolve into a solution.

There are many antistatic and electromagnetic shielding materials that can utilize conductive materials. Metal materials, inorganic materials, and organic materials.

Looking at the metal material, silver, copper aluminum and the like has been used as an electromagnetic shielding material for a long time. A thin film is used in the form of a paste inserted into a product or mixed with a binder, which is expensive, heavy, and opaque.

Second, as an inorganic material, ferrite and indium tin oxide (ITO) may be exemplified as applications in electrostatic or electromagnetic shielding. Ferrite has been used as an electromagnetic shielding material for the longest time among inorganic materials and is still used in buildings, but has a disadvantage in that the application field is limited, such as it cannot be used in electronic products. Indium tin oxide is an inorganic material, but because it has the advantage of being transparent, it is used as a transparent electrode for television CRT and LCD. However, since the high heat treatment method is used to apply the thermosetting method without the deposition because it is very expensive, the polymer product has a limitation of application and does not have the technology of synthesizing into a small particle shape, so the whole quantity is imported from foreign countries. .

Organic materials used for antistatic or electromagnetic shielding include carbon black and surfactants. Carbon black is most commonly used for antistatic purposes and is mixed with silver or aluminum to serve as an electromagnetic shielding material. However, because carbon black is a very small particle, it is not used alone but mixed with most polymers. To show conductivity, more than 30% must be mixed, which reduces the physical properties of existing polymers and prevents static electricity of electronic components and semiconductor materials. When the carbon black particles are used to contaminate parts and the working environment, the disadvantages are highlighted, and the damage caused by the current industrial sites is increasing.

In addition, surfactants, which are used as antistatic materials, cannot be used for electromagnetic shielding due to their low conductivity and are often used for antistatic purposes.They have problems such as humidity dependence and lack of long-term stability of the conductivity. If so, it is a serious problem to crawl to the surface and contaminate parts.

Conductive polymers are materials that can compensate for the shortcomings of the various antistatic and electromagnetic shielding materials mentioned above. However, the conductive polymers that have been previously published are difficult to melt or dissolve after synthesis, making it difficult to use them in coatings or polymers, and in order to achieve high conductivity, they may be used in solvents capable of weak hydrogen bonding such as m-cresol. This solvent should be dissolved, but it is not easily removed even after drying, so there is a problem such as odor due to residuals, which limits its use.

A lot of research on conductive polymers has been made in Korea and abroad. However, most attempts have been made to improve conductivity and to apply them after synthesis, and there is no description of a synthesis method that can be easily applied. For this reason, the application of a conductive polymer that is excellent in conductivity, light and in some cases transparent may still be insufficient.

Examples of conductive polymers currently on the market include W-GREEN solutions from Omecon, Germany, Baytron PH from Bayer, Germany and Panicol series from Panipol, Finland. Etc. W. Green is a product in which a binder is mixed. When the coating is applied to a polyester film, the adhesion is poor and the evaporation time of the solvent is very long. Excellent coating, but the solution itself does not have adhesion, surface hardness, chemical resistance and is difficult to apply because it is water-based.

In addition, the particle dispersion type polyaniline solution produced in Korea has a disadvantage in that the particle dispersion is poor and the electrical conductivity is low despite the high solid content, and solids are easily precipitated when mixed with general organic solvents. In addition, some companies are using polyaniline for synthesis and application because it is cheaper than other conductive polymers.

When using a commercially available conductive polymer as described above, the conductive polymer solution should be mixed with other solvents or binders in order to give physical properties, but when applied to the above products, when a solid precipitates or a binder is not used, the surface is polymer. The disadvantages of separating at the surface or dissolving in the solvent are noted. In addition, a certain binder is conventionally mixed and the solvent may be water-soluble, so there are many limitations in use, and it is very difficult to use a mixture with a polymer resin.

The present invention is very simple to synthesize the above-mentioned inconveniences can be easily synthesized in a short time and can be obtained in a dissolved state, yet a new conductive polyaniline synthesis method with good electrical conductivity and polyaniline prepared through An object of the present invention is to provide an antistatic and electromagnetic shielding material.

Synthesis method of polyaniline of the present invention

Dissolving a 0.8-2.0 molar ratio of dopant in an aniline monomer and an aniline monomer in an organic solvent and an appropriate amount of water,

Dissolving 0.4-2.0 molar ratio of oxidizing agent in water relative to the aniline monomer,

Reacting the aniline monomer, the organic solvent in which the dopant is dissolved, and the water in which the oxidant is dissolved, at 0 to 10 ° C .;

Separating the solution of polyaniline and washing with 2-5 times the washing solvent of the solution of polyaniline.

In the present invention, the main raw material used in synthesizing polyaniline is aniline or aniline having a substituent, and the aniline substituent includes one selected from methoxy group, ethoxy group, and nitro group.

Dopant is used to produce conductivity. In the present invention, any one selected from camphorsulfonic acid, dodecylsulfonic acid, and dodecyl benzenesulfonic acid, which is generally used as a dopant, may be used. There is a problem that the conductivity is low because the amount of the dopant is small, the excess dopant remaining after doping is used as an impurity when used in excess of 2.0 molar ratio dopant is recommended to use a 0.8 to 2.0 molar ratio with respect to the aniline monomer. These dopants showed the best conductivity when experimentally measured using 1.5 molar ratios for the aniline monomer and the optimum separation for polyaniline separation.

The organic solvent used to dissolve the aniline monomer and the dopant may be one selected from toluene, xylene, chloroform, ethyl acetate, methyl acetate, ethoxy methanol, butoxy ethanol. 10 times use is ideal.

The oxidizing agent may use ammonium persulfate as the initiating role of the reaction in the present invention, but if the amount of the oxidizing agent is less than 0.4 molar ratio with respect to the aniline monomer which is not dissolved in water in the present invention, there is a problem of low yield during the reaction. When the molar ratio exceeds 2.0 mole ratio with respect to the aniline monomer, the reaction proceeds rapidly, resulting in the synthesis of polyaniline having a low molecular weight and low conductivity. Thus, an oxidant dissolved in water is preferably used in a 0.4-2.0 mole ratio with respect to the aniline monomer.

The yield of polyaniline is good when the aniline monomer, the organic solvent in which the dopant is dissolved, and the water in which the oxidant is dissolved are reacted at 0 to 10 ° C. for more than 12 hours, and preferably at 0 to 2 ° C. for 12 to 14 hours.

The polyaniline-dissolved solution produced by reacting the aniline monomer, the organic solvent in which the dopant is dissolved, and the water in which the oxidant is dissolved, is left to stand for 12-24 hours or more. The solution, which has settled down and the conductive polymer polyaniline is dissolved, is separated into the upper layer.

When the polyaniline is separated for less than 12 hours, sufficient polyaniline is not separated. If the polyaniline is carried out for more than 24 hours, the polyaniline is not separated anymore, so the separation time of the polyaniline is preferably maintained for 12-24 hours.

Since the separated polyaniline solution is still unreacted, it is washed with a washing solvent to remove the unreacted material. To completely remove the unreacted material, 2-5 times the washing solvent of the polyaniline solution is used.

The washing solvent may be ethylene glycol, diethylene glycol, water, acetone or a mixture thereof. Examples of the washing solvent include water / ethylene glycol, water / acetone, acetone / ethylene glycol, and the like.

The polyaniline synthesized using the above steps has a conductivity of 1-10 S / cm and a surface resistance of 10 ^3-4 Ω / □, which is well mixed with general-purpose polymer resins and when coated on the surface of the polymer, 10 ⁵ -10 ¹⁰ Ω / It can be used as antistatic coating and can be used as antistatic and electromagnetic shielding material when mixed with general polymer resin.

Hereinafter, the present invention will be described by the following comparative examples and examples. However, these do not limit the technical scope of the present invention.

Comparative Example 1

20.5 grams (0.22 mole) of aniline and 11.5 grams (0.05 mole) of ammonium persulfate were dissolved in 1 mole hydrochloric acid solution.Then, the temperature was adjusted to 0 ° C. and the ammonium persulfate solution was slowly added.The temperature was kept at 0 ° C. for 90 minutes. React.

After stirring for 15 hours in 1 mol of hydrochloric acid solution, filter, washed and dried solid content was stirred for 15 hours in 0.1N ammonium hydroxide solution again, filtered, washed and dried in vacuum oven for 48 hours.

2 moles of camphorsulfonic acid and 1 mole of polyaniline obtained after drying in the above step were mixed and doped in a mortar, and then immersed in a 3% metacresol solution for 48 hours in ultrasonic bath and filtered by a micro filter. The measured surface resistance was 2.5 × 10 ⁵ Ω / □ and the conductivity was 20 S / cm.

Comparative Example 2

1 gram (0.06 mol) of aniline and 5.84 grams (0.1 mol) of dodecyl benzene sulfonic acid (DBSA) in dopant were dissolved in toluene and 2.44 grams (0.06 mol) of dichloro dicyanobenzoquinone, an oxidizing agent, was dissolved in toluene. The solution was slowly added and reacted at room temperature for 24 hours. Solids were made using excess methanol, filtered and dried in vacuo for 48 hours and then dissolved in toluene. However, the surface resistance was more than 10 ¹⁰ Ω / □ when most of the solids were removed and coated on PET.

<Example 1>

Dissolve 1 gram (0.06 mol) of aniline and 5.84 grams (0.1 mol) of dodecyl benzenesulfonic acid, a dopant, in 80 grams of toluene and 40 grams of water, adjust the temperature to 0 ° C, and 2.45 grams (0.06 mol) of ammonium persulfate, an oxidizing agent. After dissolving in 40 grams of water, the solution was slowly added at a temperature of 0 ° C., and reacted at 0 ° C. for 12 hours.

After the reaction, the mixture was left in a separatory funnel for 24 hours to separate the polyaniline solution, the separated polyaniline solution was washed with ethylene glycol solution, coated on a PET film, and the resistance and conductivity of the PET surface were measured by a known method. ⁴ Ω / □ and conductivity measured 4S / cm.

<Example 2>

Dissolve 1 gram (0.06 mol) of aniline and 5.84 grams (0.1 mol) of dodecyl benzenesulfonic acid, a dopant, in 80 grams of toluene and 40 grams of water, adjust the temperature to ° C, and add 2.45 grams (0.06 mol) of ammonium persulfate, an oxidant. After dissolving in 40 grams of water, the solution was slowly added at a temperature of 0 ° C., and reacted at 0 ° C. for 12 hours.

The polyaniline solution was separated in a separatory funnel for 24 hours, and the polyaniline solution was washed with a mixed solution of water: acetone 3: 1 ratio, coated on a PET film, and the resistance and conductivity of the PET surface were measured by a known method. The surface resistance was 2 × 10 ⁵ Ω / □ and the conductivity was measured as 5 × 10 ^-1 S / cm.

<Example 3>

1 gram of the polyaniline solution synthesized in Example 1 (solid content: 0.017 grams) and 0.34 grams (solid content: 0.068 grams) of a polystyrene dissolved in toluene were mixed and coated on a PET film. The measured surface resistance was 10 ⁵ Ω / □ and the conductivity was measured as 1S / cm.

The method for synthesizing polyaniline according to the present invention is very simple and can be easily synthesized in a short time, and can be obtained in a state dissolved in an organic solvent, but also has good electrical conductivity, and can be used for antistatic and electromagnetic shielding materials using polyaniline in a solution state. Can be.

Claims (8)

Dissolving a dopant in an organic solvent of 0.8-2.0 molar ratio relative to the aniline monomer and the aniline monomer, Dissolving 0.4-2.0 molar ratio of oxidizing agent in water relative to the aniline monomer, Reacting the aniline monomer, the organic solvent in which the dopant is dissolved, and the water in which the oxidant is dissolved, at 0 to 10 ° C .; Polyaniline synthesis method comprising the step of separating the polyaniline-dissolved solution and then washing with 2-5 times the washing solvent of the polyaniline-dissolved solution The method for synthesizing polyaniline according to claim 1, wherein the aniline monomer is aniline or aniline having one substituent selected from methoxy, ethoxy and nitro groups. The method of claim 1, wherein the dopant is one selected from camphorsulfonic acid, dodecylsulfonic acid, and dodecyl benzenesulfonic acid. The method of claim 1, wherein the organic solvent is one selected from toluene, xylene, chloroform, ethyl acetate, methyl acetate, ethoxy methanol, and butoxy ethanol. The method of claim 1 wherein the oxidant is ammonium persulfate. The method of claim 1, wherein the washing solvent is ethylene glycol, diethylene glycol, water, acetone or a mixture thereof. Antistatic material containing polyaniline synthesized by the method of any one of claims 1 to 6 as an active ingredient Electromagnetic shielding material containing polyaniline synthesized by the method of any one of claims 1 to 6 as an active ingredient