KR101073639B1 - Manufacturing Method for Polyurethane conductive coating resin - Google Patents

Abstract

The present invention relates to a method for preparing a polyurethane coating resin, and more particularly, a first step of preparing a prepolymer by reacting a carbon nanotube dispersion, a polyol, and a diisocyanate; And a second step of chain-extending the prepolymer.

According to the present invention, even if less CNT is used than in the related art, excellent electrical resistance characteristics can be given, and the physical properties of the polyurethane film are excellent.

Description

Manufacturing Method for Polyurethane Conductive Coating Resin

The present invention relates to a method for preparing a polyurethane coating resin, and more particularly, a first step of preparing a prepolymer by reacting a carbon nanotube dispersion, a polyol, and a diisocyanate; And a second step of chain-extending the prepolymer.

Electrically conductive polyurethane coating resins are widely used in the coating of electronic materials, clothing industry and all industries in terms of electrical properties, flexibility, mechanical strength, water resistance, wear strength, processability and economics. The present invention relates to the production of a conductive polyurethane coating resin having high electrical conductivity and excellent wear resistance and mechanical properties, and more particularly, to a modified CNT introduced functional group and a polyurethane coating resin synthesis using the same.

     The method of imparting a conductive effect to a polyurethane dry coating resin is a method of applying a conductor or a coil depending on the winding angle and diameter of a two-dimensional graphite plate where carbon atoms of carbon nanotubes combine with three other carbon atoms to form a hexagonal honeycomb pattern. Expresses the characteristics of the semiconductor. In particular, single-walled carbon nanotubes (SWNT) having a hollow cylindrical structure in which two-dimensional carbon sheets are rounded in a cylindrical shape depending on the synthesis method and conditions, and the single walls It is divided into multi-walled carbon nanotubes (MWNTs) that overlap each other in layers. These carbon nanotubes have unusual quantum phenomena observed due to their quasi one-dimensional quantum structure, and their lengths are approximately 1000 times their diameter, and the field emission effects and metals have stronger electric fields than other materials due to their length. There is a high electrical conductivity.

     Currently, carbon nanotubes are being applied as field emission devices as semiconductor components and displays (LEDs) .In the field of electrical and electronics industry, precision machinery industry, and fine chemical industry, fires caused by static electricity and malfunction of precision machinery are used. Carbon nanotube technology is actively used to prevent the production efficiency and the failure rate caused by the.

In addition, carbon nanotube technology is used to eliminate the discomfort caused by static electricity generated in household goods, clothing, and the like. Until recently, active technology development has been carried out in a wide range of fields.

The present invention is a technique to solve the dispersion problem and storage stability of the coating solution, and the resulting lowering of the physical properties of the polyurethane conductive coating resin by simply mixing the CNT dispersion in the conventional polyurethane resin as compared to the conventional products It is to provide a method for producing this excellent polyurethane coating resin.

In order to solve the above problems, the present invention comprises a first step of preparing a prepolymer by reacting the carbon nanotube dispersion, polyol and diisocyanate; And a second step of chain extending the prepolymer, wherein the first step comprises: mixing polycarbonate diol, silicon diol, and a catalyst at 80 ° C. for 30 minutes; Aliphatic diisocyanate and carbon nanotube dispersion is added to the mixture 3 to 5 times while providing a method for producing a polyurethane coating resin, characterized in that the reaction for 3 to 4 hours at 80 ℃.

The present invention, by introducing a carboxyl (COOH) functional group through the modification of the CNT, polycarbonate-diol (polycarbonate-diol), excellent wear resistance silicone diol (silicone-diol), yellowing type excellent in the polyurethane copolymer synthesis The CNT dispersion and the electrical resistance are excellent by forming a urethane bond through condensation reaction with aliphatic diisocyanate and functional modified CNT.

According to the present invention, a CNT-specific coil shape is formed by a urethane group by condensation reaction with diisocyanate using a prepolymer synthesis method. Exfoliation or intercalation of urethane groups results in a very large dispersion effect of CNTs, which can give excellent electrical resistance even when less CNTs are used. In addition, the condensation reaction between diisocyanate and CNT has the advantage that the physical properties of the polyurethane film are superior to the products in which the CNT solution is simply dispersed in a conventional polyurethane coating resin.

(Example 1: CNT Synthesis and Dispersion Preparation)

The carbon nanotube dispersions were multi-walled carbon nanotubes synthesized by Catalytic Chemical Vapor Deposition in an organic solvent and cut by ultrasonication and milling. The materials and compositions used were as follows (Fig. 1). Reference).

Table 1

Item Contents Multiwalled Carbon Nanotubes 3 ~ 5nm in diameter, purity over 95wt.% Dispersion Method Ultrasonicated 300W 30min, Ball Milling 1hr menstruum DMF Dispersant BYK190 CNT concentration 1wt.%

Experimental Example 1 CNT Dispersion

[Table 2]

Item CNT-A CNT-B CNT-C CNT type Multi-wall cnt,
3 ~ 5nm in diameter Multi-wall cnt,
1 ~ 3nm in diameter Multi-wall cnt,
3 ~ 5nm in diameter CNT pretreatment Acid treatment Acid treatment Untreated Functional group COOH COOH -

 Example 2: Synthesis of CNT-Polyurethane Copolymer

     For the synthesis of the CNT-polyurethane copolymer of the present invention, a polyol including CNT was reacted with diisocyanate to prepare a prepolymer and to extend the chain to prepare a polyurethane coating resin. CNT-polyurethane copolymer production method is a step of mixing polycarbonate diol, silicon diol and the catalyst at 80 ℃ 30 minutes and reacting for 3 to 4 hours at 80 ℃, aliphatic diisocyanate and the CNT / DMF solution The step of dividing 3 to 5 times, and after the reaction was prepared through the step of -NCO terminal identification and chain extender to complete the reaction.

1,4-butanediol, ethylene glycol and 1,6-hexnaediol were used as chain extenders.

     At this time, when the aliphatic diisocyanate is added in the process of preparing the CNT-polyurethane copolymer, the viscosity of the reactant is increased while forming a condensation polymerization with the polyol. The primary production of urethane groups therein and the formation of polyurethane prepolymers through subsequent reactions lead to intercalation of the polyurethane prepolymers into the CNTs, or CNTs through copolymerization of the inserted polyurethane prepolymers. The CNT solution was dispersed by exfoliation. The manufacturing method is a technology that can completely prevent the aggregation (aggregation) of the CNT, it is also possible to maintain the storage stability of the polyurethane coating liquid made of CNT (see Figure 2).

[Table 3]

Experimental Example 2: CNT-Polyurethane Copolymer Analysis

      1.FT-IR measurement

FT-IR measurement of the CNT-copolymerized polyurethane coating resin was confirmed that the polyurethane resin containing a typical urethane group. Specifically, the peak of the NCO group, which is a characteristic of Diisocyanate, does not appear in the FT-IR spectrum, indicating that Diisocyanate and Polyol reacted. In the spectra, the absorption peaks around 3350 cm ^-1 and 1530 cm ^-1 are characteristic peaks due to the stretching and bending vibrations of -NH- in the urethane group, respectively. The absorption peak near 1740 cm ⁻¹ is a characteristic peak represented by the stretching vibration of the carbonyl group (C═O). In addition, the absorption peak of the (-O-COO-C) characteristic of the carbonate group appeared in the vicinity of 1250cm ^-1 to confirm that the polyurethane resin using the polycarbonatediol (see Fig. 3).

2. Mechanical Properties

     CNT-copolymerized polyurethane coating resin was coated on release paper, and a film was formed to measure tensile strength, 100% elastic modulus, and elongation rate using a universal test machine, respectively. Measurement result For CNT-PU A and CNT-PU B Ref. Compared with PU, 100% elastic modulus increased 52% ~ 97%, elongation decreased 30% ~ 35%, and tensile strength was almost unchanged. On the other hand, in the case of CNT-PU C, the 100% modulus of elasticity slightly increased, but in the case of tensile strength, Ref. It showed a decrease compared to PU.

Table 4

Name of sample 100%
Modulus (kgf / cm ² ) Tensile
Strength (kgf / cm ² )
Elongation (%) Ref. PU 23.5 245 682 CNT-PU A 35.8 223 473 CNT-PU B 46.3 243 442 CNT-PU C 30.5 217 633

3. Measurement of surface resistance

      The polyurethane coating resin copolymerized with CNT was coated on a PET film with a predetermined thickness (50 μm˜100 μm), and the electrical resistance was measured by an electrical resistance meter. Surface resistance is a measure of how much the electrons on the surface of the film are disturbed to move freely, and affects the antistatic property. As a result of measuring the surface resistance of the CNT-coated polyurethane coating film according to the present invention, the surface resistance of CNT-PU A and CNT-PU B was decreased as the coating thickness was increased. In the case of CNT-PU C, the electrical resistance was not excellent because of poor dispersion state in the polyurethane resin. This can also be seen in the FE-SEM image. In particular, in the case of CNT-PU B, the electrical resistance is measured to 105 Ω or less, and when applied as a conductive coating, excellent antistatic performance can be expressed.

Item Thickness (㎛) Electrical resistance CNT-PU A 50 1.05 ~ 107 100 1.3 ~ 106 CNT-PU B 50 1.3-107 100 8.8 ~ 105 CNT-PU C 50 Not measured 100 Not measured

4. Measurement of heat resistance of film

   In order to measure the heat resistance of the polyurethane-coated resin copolymerized CNT was measured using a TGA (Thermogravimetric analyzer). Ref. CNT-PU A and CNT-PU B in the TGA graph. Compared with PU and CNT-PU C, the onset temperature of pyrolysis was higher than about 20 ℃. This is due to the addition of nano-size inorganic CNT, which contributes to the sharing of heat energy transferred into the resin and the high thermal resistance of the original CNT. heat-resistance. In particular, when the CNTs are well dispersed in the matrix polymer, the heat resistance characteristics are well expressed, and in the present invention, CNT-PU A and CNT-PU B having excellent dispersion characteristics are improved in heat resistance (see FIG. 4).

CNT dispersion characteristics analysis according to this embodiment is shown in FIG.

1 shows a process for preparing a carbon nanotube dispersion according to the present invention.

2 shows a process for producing a CNT-polyurethane copolymer according to the present invention.

Figure 3 shows the FT-IR measurement results of the CNT-coated polyurethane coating resin according to an embodiment of the present invention.

4 is a result of measuring the heat resistance of the CNT-coated polyurethane coating resin film according to an embodiment of the present invention.

5 is a photograph showing dispersion characteristics of CNTs according to an embodiment of the present invention.

(FIG. 5A shows CNT-PU-A, FIG. 5B shows CNT-PU-B, and FIG. 5C shows CNT-PU-C)

Claims (6)

A first step of preparing a prepolymer by reacting a carbon nanotube dispersion, a polyol, and a diisocyanate; And a second step of chain extending the prepolymer; The first step, Polycarbonatediol, silicondiol and catalyst were mixed at 80 ° C. for 30 minutes; Aliphatic diisocyanate and a carbon nanotube dispersion is added to the mixture 3 to 5 times while producing a polyurethane coating resin, characterized in that for 3 to 4 hours reaction at 80 ℃. delete The method of claim 1, The carbon nanotube dispersion, A method for producing a polyurethane coating resin, characterized in that the carbon nanotubes synthesized by the thermochemical vapor deposition method was put into an organic solvent and cut by ultrasonication and milling. The method of claim 3, wherein The carbon nanotube dispersion is a method for producing a polyurethane coating resin, characterized in that the functional group COOH, OH or epoxy groups are introduced by acid pretreatment. The method of claim 4, wherein The carbon nanotubes are a single-walled carbon nanotubes, multi-walled carbon nanotubes or carbon nanofibers manufacturing method of the polyurethane coating resin, characterized in that. The method of claim 5, The content of carbon nanotubes in the polyurethane coating resin is a method for producing a polyurethane coating resin, characterized in that 0.1 to 5.0% by weight.

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