KR100919611B1 - Conductive Polyurethane Resin containing Graphen - Google Patents

Abstract

The present invention relates to a conductive polyurethane resin in which graphene is dispersed, and provides a conductive polyurethane resin including polyurethane, 0.001 to 30 parts of graphene, and expanded graphite, if necessary, with respect to 100 parts of the polyurethane.

According to the present invention, it is possible to economically produce a highly conductive polyurethane resin / graphite composite and a highly conductive polyurethane film by easily dispersing graphene in a monomer or a liquid medium or a prepolymer which is a polyurethane resin raw material.

Description

Conductive Polyurethane Resin containing Graphen

The present invention relates to a conductive polyurethane resin, and more particularly to a conductive polyurethane resin containing graphene.

The conductive polymer is a material having various industrial applications such as antistatic, electrostatic dispersion, electromagnetic shielding, and transparent conductive film production. In general, the polymer material is insulative and thus mixed with a filler having electrical conductivity to impart conductivity.

Polyurethane is used in various applications such as fibers and elastomers because it can design a wide range of physical properties ranging from soft rubber properties to strong plastic properties with various combinations of monomers. Dispersed polyurethane dispersion is applied as an environmentally friendly coating containing no solvent. Therefore, in the case of imparting conductivity to these polyurethane products, its application range can be greatly expanded for the purpose of antistatic in electromagnetic related applications.

As the conductive filler of the polymer resin, metal fibers, metal flakes, carbon fibers, carbon black, carbon nanotubes, and the like are used. However, the metal material is difficult to obtain a uniform dispersion due to the large difference in specific gravity with the polymer, there is a problem that wear occurs during processing. In addition, carbon fibers reduce the inherent flexibility of the polymer material, and carbon black has a disadvantage in that a desired amount of conductivity can be obtained by using a relatively large amount.

Recently, as a lot of research on nanocomposites has been conducted, interest in manufacturing conductive nanocomposites using carbon nanotubes has increased. Carbon nanotubes can obtain high conductivity by adding a small amount of a few%, but they are expensive and difficult to disperse uniformly, which requires additional processes such as surface modification. In addition, various atoms, molecules, and ions can be inserted relatively easily, and the expanded graphite is a pressure generated between layers as the inserted material volatilizes when heated to an instantaneously high temperature by using a flame or laser irradiation. By exfoliating some layers, partially exfoliated graphite, that is, expanded graphite can be obtained. Such expanded graphite can be used as a conductive filler, but has a disadvantage in that its efficacy is lower than that of carbon nanotubes.

The present invention is to provide a conductive polyurethane resin and its composition having a high electrical conductivity while having a simple manufacturing process and economical.

The present inventors oxidized graphite powder to produce graphite oxide and instantaneously heat it to a high temperature, whereby each layer of graphite is almost individually exfoliated, that is, graphene is a commonly used intercal. Compared with partially exfoliated graphite produced through the conversion process, polar groups such as epoxy groups, carboxylic acid groups, hydroxyl groups, etc., which are formed during the oxidation process and remain during the oxidation process, are relatively easy to disperse in the polymer. The present invention has been completed by focusing on what it will do.

According to the present invention, there is provided a conductive polyurethane resin comprising polyurethane and 0.001 to 30 parts of graphene with respect to 100 parts of the polyurethane. Unless stated otherwise in the present invention, the component ratios are all weight ratios. The conductive polyurethane resin may further include expanded graphite in a ratio of 0.001 to 30 parts with respect to 100 parts of polyurethane as needed. The graphene or expanded graphite here are each preferably from 0.01 parts to 30 parts, most preferably from 0.1 parts to 20 parts with respect to 100 parts of the polyurethane. In addition, the polyurethane here includes a conventional polyurethane having a urethane bond, as well as modified by a method such as reacting other monomers such as vinyl, epoxy, or other polymers. The present invention also provides a conductive polyurethane resin composition further comprising a solvent for dissolving the polyurethane as a third component or a dispersion medium capable of dispersing the polyurethane. The dispersion medium is preferably water. The urethane resin composition may further include an emulsifier, a chain extender and / or a neutralizer. In the present invention, the polyurethane resin composition is included and used as a "polyurethane resin."

 Polyurethane is made of polyol compounds, low molecular weight hydroxy compounds, amine compounds, isocyanate compounds and the like as important components.

The polyol compound is a compound having a hydroxyl group in the sock end and has a molecular weight of hundreds to thousands of compounds, polyester diols such as polycaprolactone diol, polyethylene adipate diol, polyether diols such as polytetramethylene glycol, polypropylene glycol, etc. In addition, polyols generally used in the production of polyurethane, such as polycarbonate diols, polyolefin diols and the like, are used alone or in combination. As the low molecular weight hydroxy compound, low molecular weight diol compounds such as ethylene glycol and 1,4-butanediol are used alone or in combination.

Isocyanate compounds that are other important components of the polyurethane include aliphatic isocyanate compounds such as isophorone diisocyanate and hexamethylene diisocyanate, alicyclic isocyanate compounds such as methylene bis cyclohexanediisocyanate, and 4,4'-diphenylmethanedi. Aromatic isocyanate compounds, such as isocyanate, are used alone or in combination.

In the conductive polyurethane resin composition further comprising a solvent for dissolving the polyurethane as a third component or a medium capable of dispersing the polyurethane, in the case of the water-dispersed polyurethane in which the polyurethane is dispersed in water, a compound which provides a self-emulsifying function. , Amine compounds for chain extension, and neutralizing agents may be further used. Compounds that impart self-emulsifying function have hydroxy groups and participate in urethane reactions, and dimethylolpropanoic acid, dimethylolbutanoic acid, etc. are used as substances capable of having ionic groups for emulsification. As the amine compound for chain extension, a compound having two or more amine groups is mainly used, such as ethylenediamine and triethylenetetraamine. As the neutralizing agent, a compound having one amine group such as triethylamine is mainly used.

Graphene is prepared by oxidizing the graphite powder and then swelling and peeling the layers constituting the graphite oxide by heating the prepared graphite oxide to a high temperature instantaneously. Graphite oxide is prepared by oxidizing graphite with a mixture of sulfuric acid, a strong acid, and nitric acid, potassium chlorate, potassium permanganate, and the like. When the graphite oxide is instantaneously heated to a high temperature of 600 ° C. or more, functional groups on the surface produced by oxidation are reduced and decomposed, and gaseous products generated by vaporization are vaporized instantaneously, thereby exfoliating each layer of graphite oxide to form graphene. The degree of peeling varies depending on the degree of oxidation of the graphite oxide used for peeling, and the degree of peeling may be improved by further ultrasonication. The surface area of graphene is in the range of 10 ~ 3000 m ² / g, the larger the surface area, the greater the conductivity enhancement effect when uniformly dispersed the same amount, but relatively uniform dispersion is difficult.

In the case of expanded graphite, a material that can be decomposed by heat or light to form a gas is inserted between the layers constituting the graphite, and when heated or irradiated with light, the interlayer spacing swells like an accordion and becomes silkworm-shaped. Expanded graphite can be produced. A typical manufacturing method is that when the graphite powder or flake is immersed in sulfuric acid in the presence of oxidizing agents such as K ₂ Cr ₂ O ₇ , KMnO ₄ , HNO ₃ , (NH ₄ ) ₂ S ₂ O _8, etc., the surface of the graphite is lightly oxidized to generate a positive charge. Therefore, HSO ₄ ⁻ ions are intercalated between the layers of graphite to obtain expandable graphite, which is heated to a high temperature of 600 ° C. or higher to produce expanded graphite. Further sonication may improve the degree of expansion, with the surface area of the expanded graphite in the range of 1 to 300 m ² / g. Graphene or expanded graphite has a very small value of around several to several tens of kg / m ³ depending on the degree of exfoliation or expansion, so that it is not easy to mix uniformly with the polymeric material in a powdery state. It is advantageous for uniform dispersion to disperse and mix into a polymerization reactor. As a specific example, the method may be dispersed in acetone having high volatility, mixed with a polyol component, and then used for polymerization, a method of mixing in a molten state after polyurethane polymerization, and a method of dissolving polyurethane in a solvent and mixing it. In the case of mixing with the prepolymer and then emulsifying, mixing after emulsification, and method of adding after the end of chain extension by emulsification and amine compound.

delete

According to the present invention, high-conductivity polyurethane resin / graphite composites and highly conductive polyurethane films can be economically prepared by easily dispersing graphene and, if necessary, expanded graphite in monomer or liquid medium or prepolymer as a polyurethane resin raw material. Can be provided as

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

Preparation Example 1

Preparation of Graphite Oxide and Preparation of Peeled Graphene

     5.0 g of natural graphite powder, 87.5 mL of 98% sulfuric acid, 98% of sulfuric acid, and 45.0 mL of fuming nitric acid were added to a 3L reactor equipped with a stirrer, a thermometer, and an acid resistant pump, followed by stirring for about 1 hour while maintaining 0 ° C. 55.0 g of potassium was slowly added thereto, and the graphite was oxidized while stirring at room temperature for 120 hours. Chlorine gas generated during the oxidation process was removed with an acid resistant pump to prevent the reactor from exploding. The oxidized graphite was filtered through a filter, washed 1-2 times with 10.0 N potassium hydroxide aqueous solution, and the washed graphite oxide was washed with distilled water until the pH was about 6 again. The filtered graphite oxide was dried with a lyophilizer and used to prepare graphene.

The dry graphite oxide prepared by the above method was vertically injected into a space of argon gas atmosphere where microwaves (microwaves) of 200 to 300 W and 47 kHz were irradiated. The free-falling graphite oxide is instantaneously heated by the microwave as it passes through the space where the microwave is irradiated, and is oxidized by the gas generated as the functional groups containing oxygen on the surface of the graphite oxide are decomposed by the reduction reaction. Each layer of graphite was expanded and peeled to obtain a thin sheet of graphene having a thickness of several tens of nm and a width and length of several micrometers.

Preparation Example 2

Preparation of Expanded Graphite

     10 g of natural graphite powder was added to a 1 L reactor equipped with a stirrer and a thermometer, and 100 mL of a 98% sulfuric acid / fuming nitric acid mixture (volume ratio 4/1) was slowly added with stirring while maintaining the temperature at 0 ° C. for 24 hours at room temperature. Stirred. The graphite treated with acid was filtered, washed with distilled water until the pH was about 6, and dried at 100 ° C. for 20 hours to prepare expandable graphite. The dried sample was introduced into a 900 ° C. high temperature furnace and expanded, and 10 g of the expanded graphite was dispersed in 100 mL of acetone, and then irradiated with 70 W ultrasonic waves for 8 hours, filtered, and dried at 80 ° C. for 12 hours to expand the expanded graphite. graphite) was prepared.

Comparative Example 1

      50.00 g of polycaprolactone diol (molecular weight 2000), 13.12 g of methylene bis cyclohexanediisocyanate, and 0.02 g of a catalyst dioctyltin laurate were added to a 1 L reactor equipped with a stirrer, a thermometer, a condenser, and the result was 2 hours at 80 ° C. After the reaction, 2.25 g of 1,4-butanediol was further added thereto, and further reacted at 80 ° C. for 2 hours to synthesize a polyurethane thermoplastic elastomer. When the viscosity excessively increased during the reaction, acetone was added to adjust the viscosity, and finally, the amount of acetone was adjusted so that the content of the thermoplastic polyurethane was 40% by weight.

Example 1

      50.00 g of polycaprolactone diol and 0.65 g of graphene were premixed and prepared in the same manner as in Comparative Example 1, except that the polycaprolactone diol was used in a polymerization reaction.

Example 2

      50.00 g of polycaprolactone diol and 1.30 g of graphene were premixed and prepared in the same manner as in Comparative Example 1, except that the polycaprolactone diol was used in a polymerization reaction.

Example 3

      50.00 g of polycaprolactone diol and 1.95 g of graphene were premixed and prepared in the same manner as in Comparative Example 1, except that the polycaprolactone diol was used in a polymerization reaction.

Example 4

      Polycaprolactone diol and methylene bis cyclohexanediisocyanate were reacted at 80 ° C. for 2 hours in the presence of a catalyst, and then prepared in the same manner as in Comparative Example 1 except that 1.95 g of graphene was mixed.

Example 5

      A thermoplastic elastomer was synthesized by adding 1,4-butanediol and then prepared in the same manner as in Comparative Example 1 except that 1.95 g of graphene was mixed.

Example 6

      A thermoplastic elastomer was synthesized by adding 1,4-butanediol and then prepared in the same manner as in Comparative Example 1 except that 1.95 g of expanded graphite was mixed.

Example 7

      1,4-butanediol was added to prepare a thermoplastic elastomer, and then manufactured in the same manner as in Comparative Example 1 except that 1.00 g of graphene and 0.95 g of expanded graphite were mixed.

Comparative Example 2

      69.59 g of polybutylene adipate diol (molecular weight 2000), 4.00 g of dimethylolpropaneioic acid, 15.45 g of isophorone diisocyanate, 4,4'-diphenylmethane di in a 1 L reactor equipped with a stirrer, thermometer, condenser, etc. 8.71 g of isocyanate and 0.03 g of dioctyltinlaurate as a catalyst were added and reacted at 80 ° C. for 2 hours. Then, 1.79 g of 1,4-butanediol was added again and reacted at 80 ° C. for 1 hour to have an isocyanate group at the terminal. Polyurethane prepolymers were synthesized. When the viscosity excessively increased during the reaction, acetone was added to adjust the viscosity. After the reaction was cooled to room temperature, 3.02 g of triethylamine, a neutralizing agent, was added thereto, followed by stirring at room temperature for one hour. Then 250 mL distilled water was slowly added to emulsify the polyurethane prepolymer in water. Subsequently, 1.45 g of triethylenetetraamine dissolved in 15 mL of water was added to a reactor to react with a prepolymer to complete the polymerization reaction.

Example 8

      69.50 g of polybutylene adipate diol and 1.00 g of graphene were premixed and prepared in the same manner as in Comparative Example 2, except that the polybutylene adipate diol was used in a polymerization reaction.

Example 9

      69.50 g of polybutylene adipate diol and 2.00 g of graphene were premixed and prepared in the same manner as in Comparative Example 2, except that the polybutylene adipate diol was used in a polymerization reaction.

Example 10

      69.50 g of polybutylene adipate diol and 3.00 g of graphene were premixed and prepared in the same manner as in Comparative Example 2, except that the polybutylene adipate diol was used in a polymerization reaction.

Example 11

      69.50 g of polybutylene adipate diol and 5.00 g of graphene were premixed and prepared in the same manner as in Comparative Example 2, except that the polybutylene adipate diol was used in a polymerization reaction.

Example 12

      It was prepared in the same manner as in Comparative Example 2 except that 1,4-butanediol was added and mixed with 3.00 g of graphene after the completion of the synthesis of the polyurethane prepolymer.

Example 13

      After emulsifying the polyurethane prepolymer, 3.00 g of graphene was added thereto, followed by dissolving triethylenetetraamine in water into a reaction vessel to prepare a mixture in the same manner as in Comparative Example 2.

Example 14

It was prepared in the same manner as in Comparative Example 2 except that triethylenetetraamine dissolved in water was added to the reaction tank to react with the prepolymer to complete the polymerization reaction, and 3.00 g of graphene was added to the reaction tank and mixed.

The results of measuring the conductivity after casting the Comparative Example and Examples to make a film having a thickness of 1 mm are shown in Table 1 below. The conductivity is abruptly by adding 1 to 5 parts of graphene or expanded graphite to 100 parts of polyurethane. It can be seen that an improvement effect can be obtained.

Table 1. Conductivity Measurement Results

sample Conductivity (S / cm) Comparative Example 1 8.0 × 10 ^-12 Comparative Example 2 1.0 × 10 ^-10 Example 1 7.0 × 10 ^-9 Example 2 9.0 × 10 ^-6 Example 3 6.0 × 10 ^-4 Example 4 2.0 × 10 ^-4 Example 5 1.0 × 10 ^-4 Example 6 1.0 × 10 ^-5 Example 7 5.0 × 10 ^-5 Example 8 2.0 × 10 ^-7 Example 9 8.0 × 10 ^-5 Example 10 4.0 × 10 ^-3 Example 11 7.0 × 10 ^-2 Example 12 5.0 × 10 ^-4 Example 13 3.0 × 10 ^-3 Example 14 6.0 × 10 ^-5

Claims (8)

Conductive polyurethane resin containing polyurethane and 0.001 to 30 parts by weight of graphene based on 100 parts by weight of the polyurethane The conductive polyurethane resin of claim 1, further comprising 0.001 part by weight to 30 parts by weight based on 100 parts by weight of the expanded graphite. The conductive polyurethane resin according to claim 2, further comprising a solvent or a dispersion medium. The conductive polyurethane resin according to claim 3, further comprising a chain extender. The conductive polyurethane resin according to claim 4, further comprising a neutralizing agent. The conductive polyurethane resin according to claim 5, further comprising water as the dispersion medium and further containing an emulsifier. The conductive polyurethane resin according to any one of claims 1 to 6, wherein the graphene has a surface area of 10 to 3000 m ² / g. 8. The conductive polyurethane resin according to any one of claims 2 to 7, wherein the expanded graphite has a surface area of 1 to 300 m ² / g.