TWI384496B - Preparation method of carbon nanotube conductive thin film - Google Patents

Description

Method for manufacturing nano carbon tube conductive film

The present invention relates to a method for producing a conductive film, and more particularly to a method for producing a carbon nanotube conductive film.

With the wide application and development of LCD screens, the development of transparent conductive materials has been a hot research topic. The transparent conductive films used in displays and touch panels should have the following basic characteristics: (1) Light transmittance in the visible range Both high conductivity and (2) must be made into a smooth surface film and can withstand the plasma process environment, (3) easy to etch to form a predetermined pattern, (4) large area uniformity (5) low production cost, (6) non-toxic and capable of recycling. Indium tin oxide (ITO) has the characteristics of low film resistance and visible light transmittance of 80% to 90%, and has become the most important source of transparent conductive film. However, indium in ITO raw materials. It is a rare metal, and the production is limited, resulting in unstable supply and high raw material costs. Therefore, the development of new alternative materials has become a major issue. In addition, the touch panel and the flexible panel which have been actively invested in the industry in recent years have disadvantages in that the ITO film is relatively soft and relatively durable in use and relatively low in reliability.

In view of the insufficient source of ITO and its application limit, nanocarbon tubes are a popular alternative material developed recently, mainly because of the excellent optical, electrical, magnetic and mechanical properties of nano carbon nanotube materials. Moreover, its macroscopic physical properties and chemical properties are directly related to the microscopic arrangement and quantity of the materials themselves, and can affect the applicable product end. At present, single-walled carbon nanotubes (single) that can be put into commercial application have been developed. -walled carbon nanotubes (referred to as SWNT) conductive film.

The single-walled carbon nanotube conductive film is mainly made by a filter method and a spray method. Among them, the filter method is to first synthesize SWNT by laser, pickle it with a high concentration of nitric acid solution, add it to a solvent containing a specific surfactant to form a carbon nanotube solution, and then filter it with a specific filter paper. The carbon nanotubes are parked on the surface of the filter paper to form a carbon nanotube membrane, and then the carbon nanotube membrane is attached to the transparent substrate, and the filter paper portion is removed by acetone, leaving only the carbon nanotubes. , a single-walled carbon nanotube conductive film ("Transparent, Conductive Carbon Nanotube Films", Z. Wu etc., Science 2004 , 305, 1273, "Effect of SOCl2 Treatment on Electrical and Mechanical Properties of Single- Wall Carbon Nanotube Networks", U. Dettlaff-Weglikowska et . , J. Am. Chem. Soc ., 2005, 127, 5125-5131).

The method for preparing a single-walled carbon nanotube conductive film by spraying method is to add a predetermined amount of single-walled carbon nanotubes and disperse it in a solvent containing a specific surfactant to form a carbon nanotube solution. After centrifuging the carbon nanotube solution, a 50% portion of the upper layer of the solution was sprayed onto a poly(ethylene terephthalate, abbreviated as PET) substrate having a surface temperature maintained at 100 ° C. A single-walled carbon nanotube conductive film ("Effect of Acid Treatment on Carbon Nanotube-Based Flexible Transparent Conducting Films", J. Am. Chem. Soc ., 2007) can be obtained by washing and drying with deionized water. , 129, 7758-7759).

Although the academic and industry's active research and development, has developed a variety of transparent conductive films, and the manufacturing technology of single-walled carbon nanotube conductive film has also entered the stage of commercialization, and can replace the ITO film. Trends, but the related process technology will not be successful in a short period of time, in response to future needs, and create more humane interface products and soft electronic products, related to touch panels, flexible panels, transparent The process technology of liquid crystal displays such as electrodes will also be changed. Among them, the maturity of material technology will be a key element. Therefore, there is still a need to continuously develop different types of material technologies to provide more choices and applications. In turn, the production cost is reduced and more advanced process technology is developed.

Accordingly, it is an object of the present invention to provide a method of manufacturing a carbon nanotube conductive film which is relatively simple in process and relatively low in cost.

Thus, the method for producing a carbon nanotube conductive film of the present invention comprises the following steps:

(i) preparing a carbon nanotube solution, adding a predetermined amount of the carbon nanotube component to a predetermined amount of solvent to prepare a carbon nanotube solution having a viscosity value of 1 to 50 c.p, and the nanometer The carbon tube component has a plurality of multi-walled nanotubes (MWNTs);

(ii) atomizing, applying an ultrasonic atomization frequency to the carbon nanotube solution, atomizing the carbon nanotube solution into a plurality of atomized particles dispersed and carrying the carbon nanotubes, and providing a carrier gas transporting the atomized particles along a predetermined path, wherein the atomized particles have a particle size of between 0.5 μm and 50 μm;

(iii) spin coating, guiding the atomized particles onto a susceptor on which a substrate sheet is placed, and by rotating the susceptor, uniformly coating the atomized particles on the surface of the substrate sheet. Further, a conductive film is formed.

The invention has the beneficial effects that the multi-layered wall carbon nanotube is used as the raw material of the conductive film to effectively reduce the raw material cost, and the nanocarbon tube solution can be formed into atomized particles by applying ultrasonic waves to facilitate the nano carbon. The tube is dispersed and brought out, and the spin coating method is adopted to enable the carbon nanotubes to be uniformly coated on the surface of the substrate sheet to form a conductive film, so that the process technology of the invention is relatively simple and can save manufacturing cost. The advantages.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments of the invention.

Referring to FIG. 1 and FIG. 2, a first preferred embodiment of the method for manufacturing a carbon nanotube conductive film of the present invention comprises the following steps: Step 101 is purification, which is respectively pickled with a high concentration hydrochloric acid solution, washed with a precipitation method, and vacuumed. Drying to purify a plurality of multi-walled carbon nanotubes in a carbon nanotube component, the main purpose of the purification treatment is to remove iron oxide, amorphous carbon, surface functional groups and the like in the raw materials of the carbon nanotubes. Or impurities mixed in the carbon nanotube raw materials to improve the conductivity of the multi-walled carbon nanotubes, thereby enabling the carbon nanotubes to exhibit better photoelectric properties.

Step 102 is to prepare a carbon nanotube solution 30, and add 1 part by weight of the carbon nanotube component and 1 part by weight of the surfactant component to 1000 to 1,000,000 parts by weight of the solvent respectively to prepare a viscosity value of 1 ~50c.p of carbon nanotube solution 30, and the carbon nanotube component has a plurality of multi-layered wall carbon nanotubes.

The surfactant component is for preventing the aggregation of the multi-walled nanotubes, and is a substance selected from the group consisting of a sulfated alcohol (ROSO ₃ ^- M ⁺ ) , alkylsulfonate (formula RSO ₃ ^- M ⁺ ), α-olefin sulfonate (alpha-olefinsulphonate, abbreviated as AOS, of the formula RCH=CH(CH ₂ ) _n -SO ₃ M) Quaternary ammonium salt ), ethylene oxide (also known as polyethylene glycol, polyoxyethylene, POE for short), polyoxyethylene alkyl ether (also known as fatty alcohol polyoxyethylene ether, ether alcohol, alcohol ethoxylate, referred to as AE, The formula is RO(CH ₂ CH ₂ O) _n H), and combinations thereof.

Preferably, the surfactant is a substance selected from the group consisting of sodium C ₄ ~ C ₁₈ linear alkyl sulfonate (formula RSO ₃ ^- Na ⁺ ), C ₄ ~ C ₁₈ straight Potassium alkane sulfonate (formula RSO ₃ ^- K ⁺ ), linear alkyl sodium sulfate of C ₄ ~ C ₁₈ (formula of ROSO ₃ ^- Na ⁺ ), linear alkyl group of C ₄ ~ C ₁₈ Potassium sulfate (formula of ROSO ₃ ^- K ⁺ ), sodium C ₄ ~ C ₁₈ linear alkylbenzene sulfonate (formula RC ₆ H ₄ SO ₃ ^- Na ⁺ ), linear chain of C ₄ ~ C ₁₈ Potassium alkylbenzene sulfonate (formula RC ₆ H ₄ SO ₃ ^- K ⁺ ), linear C ₄ -C ₁₈ linear alkyl benzene sulphate (formula: ROC ₆ H ₄ SO ₃ ^- Na ⁺ ), C ₄ to C ₁₈ linear alkyl benzene sulfate (formula: ROC ₆ H ₄ SO ₃ ^- K ⁺ ), C ₂ to C ₁₆ linear alkyl quaternary ammonium salt, α-olefin sulfonate (abbreviation is the AOS, the formula _{RCH = CH (CH 2) n} -SO 3 M, where, n = 14 ~ 16, and M is an alkali metal ion group), alkyl polyoxyethylene alkyl is a C ₂ ~ C ₁₆ of Ether (abbreviated as AE, the formula is RO(CH ₂ CH ₂ O) _n H, n=5~30), and combinations thereof. Thereby, a better dispersion effect can be achieved. In the present embodiment, sodium dodecyl sulfate (SDS) is selected as the surfactant.

Wherein the solvent is a liquid selected from the group consisting of water, ethanol, isopropanol and acetone. In the preparation, after adding the multi-layered wall carbon nanotube component and the surfactant to the solvent, the probe type ultrasonic oscillating disperser with a power of 750W can be used first (model: Sonics & Materials, Inc. "SONICS VCX750") The MWNT solution was applied at 20% power for 5 minutes and 30% power for 5 minutes to prevent the multi-walled nanotubes from collecting and being uniformly dispersed.

Step 103 is atomization, applying an ultrasonic atomization frequency to the carbon nanotube solution 30, and atomizing the carbon nanotube solution 30 into a plurality of atomized particles 31 dispersed with the carbon nanotubes. And carrying a carrier gas 32 to transport the atomized particles 31 along a predetermined path. Wherein, the carbon nanotube solution 30 is contained in an atomizing container 33, and the liquid level of the solution 30 is maintained at a fixed height by a siphon tube 34, thereby generating an ultrasonic component of the ultrasonic frequency. 35 is constant at a fixed depth below the liquid surface to control the energy of the liquid level of the solution to be fixed, and the particle size of the atomized particles 31 produced can be maintained consistently. The siphon tube 34 is connected between the atomization container 33 and a liquid storage container 38. The liquid storage container 38 is placed on a lifting seat 39 to be vertically displaced by the linkage thereof, and can thereby control the The liquid level in the atomizing container 33. Preferably, in order to maintain the dispersed state of the carbon nanotubes flowing into the carbon nanotube solution 30 of the liquid storage container 38, a probe type ultrasonic wave is usually added to the liquid storage device 38. An oscillating disperser (not shown) continues to act on the solution that is returned to the reservoir 38.

Preferably, the ultrasonic atomization frequency is 20 kHz to 2.45 MHz, and in this embodiment, the ultrasonic atomization frequency of 1.65 MHz is used (the ultrasonic atomizer used in the embodiment is: Pro-Wave Electronic Corp M165D25, M165D20), and the particle size of the atomized particles 31 is between 0.5 μm and 50 μm, and preferably between 2 μm and 7 μm. In this embodiment, The particle diameter of the atomized particles 31 is substantially maintained at about 3 μm in accordance with the ultrasonic atomization frequency.

In order to meet the required particle size, the frequency range of the ultrasonic wave can be estimated by the following formula to adjust to the required atomized particle size 31 more quickly:

Where D is the particle size of the atomized particles, T is the surface tension coefficient (N/cm), ρ is the solution density (g/cm ³ ), f is the ultrasonic atomization frequency (Hz), and α is 0.34. Value. (Ultrasonics Volume 22, Issue 6, November 1984, Pages 259-260)

Preferably, the flow rate of the carrier gas 32 is from 1 L/min to 200 L/min. In the present embodiment, the flow rate of the carrier gas 32 is set to 22 L/min, and the carrier gas 32 is nitrogen.

Step 104 is spin coating, and the atomized particles 31 are guided onto a susceptor 37 on which a substrate sheet 36 is placed. By rotating the susceptor 37, the atomized particles 31 are uniformly coated on the substrate. The surface of the substrate sheet 36 forms a conductive film.

When the rotating cloth is rotated, the susceptor 37 is pre-treated by one wet spin coating and one preliminary film spin coating, and then repeated periodic re-filming spin coating is repeated, and the repulsion is repeated. In the film spin coating, the rotation is sequentially performed through a cycle of a low speed, a medium speed, and a high speed, and the ratio of the low speed, the medium speed, and the high speed is 2 to 3:3 to 6:8 to 40. In this embodiment, the low speed is preferably 300 to 450 r.p.m., and the medium speed is preferably controlled at 450 to 900 r.p.m., and the high speed is preferably 1200 to 6000 r.p.m. Among them, the rotational speed of the wet spin coating is 300r.pm and 450r.pm alternately, and the rotational speed of the preliminary film spin coating is from 450r.pm to 6000r.pm, and then enters the cycle. Sexual re-filming rotation.

Step 105 is hot pressing, applying a predetermined pressure to the substrate sheet 36 provided with the conductive film at a predetermined temperature for compacting and compacting the conductive film to form a denser and stable structure, and making the plurality of layers The tight junction between the wall carbon nanotubes helps to reduce the surface resistance of the conductive film, so that the conductive film can exhibit better conductivity.

Preferably, when hot pressing is performed, a pressure of 1 to 200 kg/cm ² is applied at a temperature of 50 ° C to 110 ° C for 30 seconds to 30 minutes, and in the present embodiment, 100 kg / is applied at a temperature of 70 ° C. The pressure of cm ² is hot pressed for 30 minutes, but this should not limit the hot pressing time. Generally, the longer the hot pressing, the better the conductivity, but the increase in conductivity after hot pressing for more than 30 minutes is not significant, so the hot pressing time Should be controlled within 30 minutes.

Step 106 is cleaning. The substrate sheet 36 having a conductive film is firstly rinsed in deionized water for 5 to 30 minutes, and soaked for 2 hours for water exchange, repeated 5 times, and then soaked in ethanol for 2 hours, and then at a temperature of 60 ° C. A vacuum is applied, whereby the surfactant remaining in the conductive film can be removed to prevent the residual impurities from causing a decrease in the conductivity of the conductive film. After the cleaning is completed and dried, the finished multilayered carbon nanotube conductive film bonded to the substrate sheet 36 can be obtained.

<Specific example>

(1) Purification of 1 g of multi-layered wall carbon nanotubes (MWNT): first prepare 250 ml of 6 M concentrated hydrochloric acid solution, then put 1 g of MWNT into the hydrochloric acid solution, stir for 24 hours, and then continuously wash 6 times by precipitation. Then, reconstitute 250 ml of 6M hydrochloric acid, and then continue to purify MWNT by the above-mentioned pickling and washing, so that the MWNT is purified three times at a temperature of 80 ° C, 12 hours and a temperature of 250 ° C for 24 hours. It was vacuum dried and placed in a nitrogen oven to dry at a temperature of 400 °C.

(2) Configure 10mg/L MWNT aqueous solution: Put 10mg MWNT and 10mg SDS in 1L deionized water, first use the probe 750W ultrasonic shock diffuser (model: Sonics & Materials, Inc. SONICS VCX750") The MWNT solution was applied at 20% power for 5 minutes and 30% power for 5 minutes to prevent the multi-walled nanotubes from collecting and being uniformly dispersed.

(3) Atomization: The ultrasonic atomizer is placed at a depth of 3.0 cm below the liquid surface, and the temperature of the solution is maintained at 30 ° C, and an ultrasonic atomization frequency of 1.65 MHz is provided to act on the carbon nanotube solution. , the atomization rate of 25~30ml/hr can be achieved, and the particle size of the atomized particles is about 3μm, and the carrier gas is fed into the gas pipe connected with the container containing the MWNT solution, and the flow rate of the carrier gas is 22L. /min.

(4) spin coating: the carrier gas guides the atomized particles onto a susceptor of a spin coater, and the substrate sheet placed on the susceptor is rotated synchronously with the susceptor for spin coating Before, the substrate sheet was washed with deionized water for 40 seconds at a speed of 500 rpm, and then washed with alcohol at a speed of 800 rpm for 60 seconds, and then spin coating of the ultrasonic atomized particles. .

When the spin coating of the ultrasonic atomized particles is performed, the pretreatment is performed by one wet spin coating and one preliminary film spin coating, and the periodic recoating spin coating is repeated a plurality of times. Among them, the rotational speed of the wet spin coating is 300r.pm and 450r.pm alternately, and the rotational speed of the preliminary film spin coating is from 450r.pm to 6000r.pm, and then enters the cycle. Sex re-filming spin coating. During the coating process, the susceptor is continuously rotated in a staged cycle as shown in FIG. 5, and the interval (I) represents the change in the rotational speed of the wet spin coating, and the interval (II) represents the preliminary film forming spin coating. The stepwise speed change, the sections (III), (IV), and (V) are all stepwise rotational speed changes of the re-filming spin coating, thereby enabling the atomized particles to be uniformly applied to the base. The surface of the sheet is controlled, and the film thickness of the conductive film can be controlled by the length of the spin coating. In Fig. 5, the different stages are respectively represented by different letters, and the rotation speed and time represented by them are arranged as shown in Table 1 below. The time of each stage in Table 1 should not be limited, and can be adjusted according to actual needs.

The spin coating time is controlled from 10 minutes to 60 minutes to control the spin coating time to achieve the design specifications of the multilayered nano-carbon nanotube conductive film, which is mainly by adjusting c~ The time of f is used to adjust the thickness of the conductive film.

(5) Hot pressing: the temperature of the upper and lower stampers of a hot press is raised to 70 ° C, and the temperature is maintained for 1 hour, and the temperature fluctuation is controlled below ± 0.25 ° C, and four pieces of 5 cm × 5 cm PET sheets are cut. And rinsing the PET sheets in a cleaning sequence of deionized water, ethanol, deionized water, acetone, and deionized water, respectively, and sandwiching the substrate sheets on which the conductive film is disposed, in the manner of two sheets above, Then, a stainless steel jig of 10 cm×10 cm was placed on top of the PET sheet, and the combined substrate sheet, PET sheet and stainless steel jig were placed between the upper and lower stampers of the hot press, and 100 kg/cm ² was applied. The pressure is hot pressed for 30 minutes.

(6) Cleaning: The multi-layered wall carbon nanotube conductive film can be obtained by washing the hot-pressed conductive film substrate sheet in the manner described in the above step 106.

<Flexibility test>

Referring to Fig. 6, the prepared substrate sheet with the conductive film was cut into a test piece 51 of 1 cm × 2 cm, and the conductivity of the test piece 51 before being bent was measured. Then, the opposite sides of the longer side of the test piece 51 are respectively fixed to a fixed clip 52, and a movable clip 53 spaced apart from the fixed clip 51, and the movable clip 53 is biased toward the opposite side. The fixing clip 51 is displaced to the opposite side of the long side of the test piece 51 by a distance of 1 cm, and further displaced to a distance of 0.5 cm on the opposite side of the long side of the test piece 51, the test piece 51 will follow The movement of the movable clamp 53 is bent and bent, and then the movable clamp 53 is displaced away from the fixed clamp 52, and the test piece 51 is returned to a flat state, and the test piece 51 is measured to be bent. The folded sheet resistance repeats the above-described operation of flexing and bending the test piece 51, and the test piece 51 is again measured once after returning to the flat state, and the sheet resistance can be correspondingly reacted by the change of the sheet resistance. The change in conductivity, the more stable the sheet resistance value, the more stable the conductivity.

A carbon nanotube conductive film (indicated by CNT/PET) is formed on the surface of a PET substrate, and an ITO film (indicated by ITO/PET) is formed on another PET substrate, and CNT/PET, ITO/ respectively. PET is cut to the test piece of the above-mentioned size for the flexural resistance test. The original sheet resistance of the ITO/PET test piece before the untwisted is ITO/PET≒120Ω/□, (where □ =cm ² , ie Ω/□=Ω/cm ² ), CNT/PET≒100Ω/□, the sheet resistance of ITO/PET and CNT/PET will be unstable due to the previous several bends. It is impossible to make a clear comparison. Therefore, the test pieces of ITO/PET and CNT/PET are each bent 50 times to stabilize the sheet resistance (conductivity), and then the flexural resistance test is officially entered. Among them, the sheet resistance values after stabilization for 50 times are ITO/PET≒5KΩ/□, CNT/PET≒3KΩ/□, and the test results are shown in the following table. The number of bends in Table 1 does not include the advance. Number of bends 50 times:

The test results show that the sheet resistance of the CNT/PET specimen after bending 100 times is increased by 10%, the sheet resistance after twisting 250 times is increased by 20%, and the sheet resistance after bending for 500 times is increased by 20%, which is the same as that of ITO/PET. Compared with the sheet resistance after the number of deflections, the increase ratio of the sheet resistance is small, and it can be inferred that the ratio of decrease in conductivity is also smaller than that of ITO/PET, indicating that the conductive film of the present invention is preferable. Flexibility.

<Reproducibility measurement of different test pieces produced under the same preparation conditions>

According to the conditions of <specific example>, five test pieces were respectively prepared, and the transmittances of light of different wavelengths were measured, and the results shown in Fig. 7 were obtained, and the curve numbers 61 to 65 respectively represent the measurement of five different test pieces. As a result, it can be seen from the graph that the shape of the curve measured for each of the test pieces is similar and extremely close, showing that the manufacturing method of the present invention has excellent reproducibility.

With reference to the numerical values of the graphs of FIG. 7, the transmittances at wavelengths of 350 nm, 400 nm, 450 nm, 500 nm, and 550 nm (%T) were calculated at specific wavelengths (ie, 350 nm, 400 nm, 450 nm, 500 nm). The arithmetic mean deviation at 550 nm). Calculated as follows:

Arithmetic mean deviation:

among them, Indicates the arithmetic mean deviation of the number 61~65 test piece at a specific wavelength, and X is the light transmittance (%T) of the test piece at a specific wavelength of the number 61~65. The average transmittance value of the test piece numbered 61-65 at a specific wavelength, and n is the number of test pieces (here n=5).

The calculation results show that the arithmetic mean deviation of the transmittance of the test pieces at a specific wavelength is less than 0.5% T, which shows the average deviation of the transmittance of the conductive film produced by the manufacturing method of the present invention at a specific wavelength. It can be controlled below 0.5% T with excellent reproducibility.

<Measurement of film thickness uniformity of the same sample>

Referring to FIG. 8, a conductive thin film test piece is prepared according to the conditions and steps of <Specific Example>, and three different positions 71, 72, and 73 are arbitrarily designated in the same test piece, and the three areas 71, 72, and 73 are respectively measured. The transmittance of light waves of different wavelengths, as shown in FIG. 8, shows that the wavelength-transmittance curves measured in different regions of the test piece almost coincide, showing that the transmittances of different positions of the test piece are consistent and can From this, it is presumed that the film thickness is the same, and it is shown that the conductive film test piece produced by the present invention has a preferable film thickness uniformity.

The transmittance (%T) of the same test piece at the same wavelength was taken at a specific wavelength of 30 nm to 800 nm, and the arithmetic mean deviation was calculated to confirm the average deviation value of the transmittance of the same test piece at different positions. Calculated as follows:

Arithmetic mean deviation:

among them, Indicates the arithmetic mean deviation of the number 71 to 73 in the same test piece at a specific wavelength, and X is the transmittance (%T) of the region at the specific wavelength of the number 71 to 73. The average transmittance value at a specific wavelength for the number 71 to 73, and n is the number of sampling regions (here n=3).

The calculation results show that the arithmetic mean deviation of the transmittance of different regions of the same test piece at a specific wavelength is less than 0.3% T, which shows that the transmittance values of the same sample in different regions are consistent, and the different regions of the same sample can be inferred accordingly. The film thickness uniformity is good.

<Transmission change and resistance change of light at 550 nm wavelength at different spin coating times>

According to the conditions of <Specific Example>, three sheets of conductive thin film strips were spin-coated for 5, 15, 30, 45, 60, and 120 minutes, respectively, and the penetration of each test piece at 550 nm wavelength was measured. Rate and sheet resistance. Then, the values measured by the test piece prepared by the same spin coating time are averaged, and the measured results can be arranged as shown in Table 2, respectively, with the spin coating time as the abscissa and the penetration rate as the ordinate. Fig. 9 and the rotational coating time as the abscissa, and the measured value of the sheet resistance value after log calculation is plotted as an ordinate.

Theoretically, the longer the spin coating time, the more atomized particles coated on the substrate sheet, and the thicker the thickness of the finally formed conductive film. Therefore, referring to FIG. 9 and FIG. 10, the measurement results are obtained. It is also shown that the longer the spin coating time, the lower the transmittance of the conductive film under the light of 550 nm wavelength, and the resistance value of the conductive film also decreases as the film thickness increases, the display film The increase in thickness has better conductivity, but the transmittance of light at a specific wavelength is reduced. The sheet resistance of a conductive film that is generally applicable is in the range of 10 to 800 Ω/cm ² , and the conductive film used in a general touch panel. The sheet resistance specification is in the range of 200 to 800 Ω/cm ² , and it is shown that the sheet resistance value of the electroconductive film produced by the present invention has met the application specifications. The carbon nanotube conductive film produced by the invention has a light transmittance corresponding to a sheet resistance of 65% to 90% in the same range, and a light transmittance of 550 nm of a conductive film which is generally applicable. Compared with %~90%, it is shown that the carbon nanotube conductive film prepared by the manufacturing method of the invention has practical application value.

Referring to FIG. 3 and FIG. 4, a second preferred embodiment of the method for manufacturing a carbon nanotube conductive film of the present invention comprises the following steps: Step 201 is to purify the multi-layered wall in the carbon nanotube component. Carbon tube.

Step 202 is to prepare a carbon nanotube solution 40, and add 1 part by weight of the carbon nanotube component to 1000 to 1,000,000 parts by weight of a solvent to prepare a carbon nanotube having a viscosity value of 1 to 50 c.p. The solution, the ratio of the amount of the carbon nanotube component to the solvent, and the type of solvent that can be used are the same as those described in the step 102 of the first preferred embodiment, and therefore will not be described again. The main difference lies in the second preferred. No surfactant was added to the carbon nanotube solution 40 in the examples.

Step 203 is ultrasonic oscillating dispersion. The carbon nanotube solution prepared in step 202 is added to the dispersion container 41 by using a dispersion container 41 and an atomization container 42 connected to each other, and the dispersion container 41 is disposed in the dispersion container 41. The carbon nanotube solution 40 is applied with an ultrasonic oscillating dispersion to prevent the carbon nanotubes in the carbon nanotube solution 40 from agglomerating to provide an effect of adding a surfactant by ultrasonic oscillating energy, and then The oscillating carbon nanotube solution 40 then flows continuously from the dispersion vessel into the atomization vessel 42 via a siphon 46.

Among them, the ultrasonic disperser 43 providing the oscillating dispersion is a probe type ultrasonic oscillating disperser (model: Sonics & Materials, Inc. "SONICS VCX750"), its working power is preferably 750W, and it acts on the carbon nanotube solution at 20% power for 5 minutes, and 30% power for 5 minutes.

It should be noted that when the carbon nanotube solution 40 is prepared in step 202, the surfactant may be further added, and the ultrasonic vibration dispersion treatment in step 203 may be used to promote the carbon nanotubes. The dispersion effect.

It should be added that if the MWNT solution containing no surfactant is disposed, after the ultrasonic vibration is dispersed, the carbon nanotubes will re-aggregate after being dispersed for a period of time, and the dispersion can be maintained for 20 seconds. For 30 seconds, a relatively low concentration MWNT solution, for example, a 2 mg/L MWNT solution, is then placed, and the oscillated solution is successively directed into the atomizing container 42 by the siphon 46. When the MWNT solution achieves the dispersion effect by means of ultrasonic vibration, the spin coating time is relatively extended from 15 minutes to 120 minutes due to the low concentration of the MWNT solution used.

Step 204 is atomization, applying an ultrasonic atomization frequency to the carbon nanotube solution 40 guided into the atomization container 42 to atomize the carbon nanotube solution 40 into a plurality of dispersions and carrying the same The carbon nanotubes atomize the particles 44 and provide a carrier gas 45 to transport the atomized particles along a path. The parameters of the ultrasonic frequency and their relationship with the particle size of the atomized particles 44 are compared with the first The content of step 103 of the preferred embodiment is the same, and therefore will not be described again.

Wherein, the excess carbon nanotube solution 40 is flowed into the dispersion container 41 by using a siphon 46 connected between the atomization container 42 and the dispersion container 41 to reach the nanocarbon in the atomization container 42. The tube solution 40 is maintained for a predetermined height.

Step 205 is spin coating, step 206 is hot pressing, and step 207 is cleaning. The manner and parameter conditions are the same as steps 104, 105 and 106 of the first preferred embodiment, respectively, and therefore will not be described again.

In summary, the method for producing a carbon nanotube conductive film of the present invention can attain the following effects and advantages, thereby achieving the object of the present invention:

1. By providing a specific ultrasonic frequency to form the atomized particles of the carbon nanotube solution, and then applying the gas to the rotating substrate sheet, a conductive film having a uniform thickness can be obtained. The invention can be easily sprayed by a spray gun method, an ink jet method of an ink jet printer, a immersion plating method or a filter film preparation technique, or a physical sputtering method of an ITO conductive film which is generally used in the industry. The obtained equipment and the relatively simple process achieve the result of producing a carbon nanotube conductive film, and have the advantages of reducing the manufacturing cost and the value for commercial application.

Second, the thickness of the conductive film finally obtained can be controlled by the length of the spin coating to correspondingly produce conductive films with different transmittances and different resistance specifications, so that the manufacturing method of the present invention can be adjusted in a relatively simple control manner. The quality of the products is used in conjunction with different grades of application products.

3. The results of the flexural resistance test show that the conductive film prepared by the manufacturing method of the present invention has a plurality of flexural properties, and the electrical conductivity thereof still meets the required application specifications, so that the manufacturing method of the present invention can be produced. Good resistance flexible conductive film.

Fourth, by using the manufacturing method of the present invention, it is possible to produce a conductive film product conforming to industry specifications by using a relatively low cost multi-layered wall carbon nanotube as a raw material, and has the advantage of reducing manufacturing cost.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

30. . . Nano carbon tube solution

31. . . Atomized particle

32. . . Carrying gas

33. . . Atomizing container

34. . . siphon

35. . . Ultrasonic component

36. . . Substrate sheet

37. . . Pedestal

38. . . Liquid container

39. . . Lifting seat

40. . . Nano carbon tube solution

41. . . Dispersed container

42. . . Atomizing container

43. . . Ultrasonic diffuser

44. . . Atomized particle

45. . . Carrying gas

46. . . siphon

51. . . Conductive film test piece

52. . . Fixed clamp

53. . . Activity holder

1 is a flow chart showing a first preferred embodiment of a method for producing a carbon nanotube conductive film of the present invention;

Figure 2 is a schematic view showing the combination of the devices used in the first preferred embodiment;

Figure 3 is a flow chart showing a second preferred embodiment of the method for producing a carbon nanotube conductive film of the present invention;

Figure 4 is a schematic view showing the combination of the devices used in the second preferred embodiment;

Figure 5 is a schematic view showing the change of the rotational speed set at different times during the spin coating of the first preferred embodiment;

Figure 6 is a schematic view showing the process of conducting a flexural test on the conductive film test piece produced by the manufacturing method of the present invention;

Figure 7 is a graph showing the transmittance change curve of different conductive film test pieces produced by the manufacturing method of the present invention;

Figure 8 is a graph showing the change in transmittance at different positions on a conductive film test piece produced by the manufacturing method of the present invention;

Figure 9 is a graph showing changes in the transmittance of a conductive film test piece produced by different spin coating times of the manufacturing method of the present invention;

Fig. 10 is a graph showing changes in sheet resistance of a conductive thin film test piece produced by the spin coating time of the manufacturing method of the present invention.

Claims (27)

A method for manufacturing a carbon nanotube conductive film, comprising the steps of: (i) preparing a carbon nanotube solution, adding a predetermined amount of carbon nanotube components to a predetermined amount of solvent to prepare a viscosity value of 1 ~50c.p of carbon nanotube solution, and the carbon nanotube component has a plurality of multi-walled carbon nanotubes; (ii) atomization, applying an ultrasonic atomization frequency to the carbon nanotube solution, The carbon nanotube solution is atomized into a plurality of atomized particles dispersed and carrying the carbon nanotubes, and a carrier gas is provided to transport the atomized particles along a predetermined path, wherein the atomization The particle size of the particles is between 0.5 μm and 50 μm; (iii) spin coating, directing the atomized particles onto a susceptor on which a substrate sheet is placed, and rotating the susceptor to atomize the particles The particles are uniformly coated on the surface of the substrate sheet to form a conductive film. The method for producing a carbon nanotube conductive film according to claim 1, wherein in the step (i), the solvent is a liquid selected from the group consisting of water, ethanol, isopropanol and acetone. The method for producing a carbon nanotube conductive film according to claim 2, wherein in the step (i), the carbon nanotube solution further has a predetermined amount of a surfactant component, and the interface The active agent component is used to prevent aggregation of the multi-walled nanotubes in the carbon nanotube component. The method for producing a carbon nanotube conductive film according to claim 3, wherein the surfactant component is a substance selected from the group consisting of a sulfate salt of an alcohol and an alkyl sulfonate. , a-olefin sulfonate, a fourth ammonium salt, an ethylene oxide system, a polyoxyethylene alkyl ether, and combinations thereof. The method for producing a carbon nanotube conductive film according to claim 4, wherein the surfactant component is a substance selected from the group consisting of C ₄ to C ₁₈ linear alkyl groups. sodium, potassium linear alkyl sulfonate of C ₄ ~ C ₁₈ straight-chain alkyl sulfate of C ₄ ~ C ₁₈ straight-chain alkyl sulfate of C ₄ ~ C _18, C ₄ ~ C ₁₈ of linear alkylbenzene sulfonate, C linear alkylbenzene sulfonate, potassium ₄ ~ C _18, the linear alkyl benzene sulfate of C ₄ ~ C ₁₈ straight-chain C ₄ ~ C ₁₈ alkyl sulfate of Potassium, C ₂ -C ₁₆ linear alkyl quaternary ammonium salts, α-olefin sulfonates, alkyl groups are C ₂ -C ₁₆ polyoxyethylene alkyl ethers, and combinations thereof. The method for producing a carbon nanotube conductive film according to claim 5, wherein the surfactant component is selected from sodium dodecyl sulfate. The method for producing a carbon nanotube conductive film according to claim 2, wherein in the step (ii), the ultrasonic atomization frequency is 20 kHz to 2.45 MHz. The method for producing a carbon nanotube conductive film according to claim 7, wherein in the step (ii), the ultrasonic atomization frequency is 1.65 MHz. The method for producing a carbon nanotube conductive film according to claim 7, wherein in the step (ii), the atomized particles have a particle diameter of 2 μm to 7 μm. The method for producing a carbon nanotube conductive film according to claim 9, wherein in the step (ii), the atomized particles have a particle diameter of substantially 3 μm. The method for producing a carbon nanotube conductive film according to claim 10, wherein in the step (i), the carbon nanotube solution has 1 part by weight of a surfactant component, and 1 part by weight The carbon nanotube component, and 1000 to 1,000,000 parts by weight of the solvent. The method for producing a carbon nanotube conductive film according to claim 11, further comprising a step (iv) after the step (iii), wherein the step (iv) is cleaning for removing the residual conductive film. The surfactant in the medium. The method for producing a carbon nanotube conductive film according to claim 12, wherein in the step (iv), the substrate sheet having the conductive film is firstly rinsed in deionized water 5 to 30. Minutes, and soaked for 2 hours for water change, repeated 5 times, then soaked in ethanol for 2 hours, and then vacuumed at a temperature of 60 ° C for 12 hours. The method for producing a carbon nanotube conductive film according to claim 1, further comprising a step (a) between the step (i) and the step (ii), wherein the step (a) is ultrasonic vibration dispersion Providing a dispersion container and an atomization container respectively connected to each other, and respectively applying the ultrasonic atomization frequency to the carbon nanotube solution located in the atomization container to atomize the carbon nanotube solution. And applying an ultrasonic oscillating dispersion to the carbon nanotube solution in the dispersion container to prevent the carbon nanotubes from accumulating in the carbon nanotube solution, and the carrier gas is introduced into the atomization container Directing the atomized particles to the base of step (iii), the carbon nanotube solution is firstly subjected to ultrasonic wave dispersion in the dispersion container, and then guided into the atomization container to receive the Ultrasonic atomization frequency action. The method for manufacturing a carbon nanotube conductive film according to claim 14, wherein the ultrasonic oscillation is provided by an ultrasonic disperser having a power of 700 W, and the carbon nanotube solution is 20 The % power is applied for 5 minutes and the 30% power is applied for 5 minutes. The method for producing a carbon nanotube conductive film according to claim 15, wherein in the step (ii), the atomized particles have a particle diameter of 2 μm to 7 μm. The method for producing a carbon nanotube conductive film according to claim 16, wherein in the step (ii), the atomized particles have a particle diameter of substantially 3 μm. The method for producing a carbon nanotube conductive film according to claim 17, wherein in the step (i), the carbon nanotube solution has 1 part by weight of a surfactant component and 1 part by weight. The carbon nanotube component, and 1000 to 1,000,000 parts by weight of the solvent. The method for producing a carbon nanotube conductive film according to claim 9 or claim 16, wherein in the step (ii), the flow rate of the carrier gas is from 1 L/min to 200 L/min. The method for producing a carbon nanotube conductive film according to claim 19, wherein in the step (ii), the flow rate of the carrier gas is substantially 22 L/min. The method for producing a carbon nanotube conductive film according to claim 20, wherein, in the step (iii), when the spin coating is performed, the susceptor is first subjected to a wet spin coating and a preliminary formation. Film spin coating Pre-treating, performing at least one periodic re-filming spin coating, and sequentially rotating the cycle through a low-speed rotation speed, a medium-speed rotation speed, and a high-speed rotation speed in the re-filming rotary coating, and The ratio of low speed, medium speed and high speed speed is 2~3:3~6:8~40. The method for producing a carbon nanotube conductive film according to claim 21, wherein in the step (iii), the low speed is 300 to 450 rpm, and the medium speed is 450 to 900 rpm, and The high speed is 1200~6000 rpm. The method for producing a carbon nanotube conductive film according to claim 22, wherein in the step (iii), the rotational rotation coating is performed at a number of revolutions of 300 rpm and 450 rpm for several times. The rotational speed of film-forming spin coating is stepped up to 6000 rpm from 450 rpm, and then enters a periodic re-filming spin coating. The method for producing a carbon nanotube conductive film according to claim 23, further comprising a step (b) before the step (i), wherein the step (b) is to purify the multi-walled carbon nanotubes, which are respectively The multi-walled carbon nanotubes are purified by pickling with a high concentration hydrochloric acid solution, washing with a precipitation method, and vacuum drying. The method for producing a carbon nanotube conductive film according to claim 12 or 13, further comprising a step (c) between the step (iii) and the step (iv), the step (c) It is a hot press which applies a predetermined pressure to a substrate sheet provided with the electroconductive film at a predetermined temperature for compacting and compacting the electroconductive film. The method for producing a carbon nanotube conductive film according to claim 25, wherein in the step (c), a pressure hot pressing of 1 to 200 kg/cm ² is applied at a temperature of 50 ° C to 110 ° C. Seconds ~ 30 minutes. The method for producing a carbon nanotube conductive film according to claim 26, wherein in the step (c), a pressure of 100 kg/cm ² is applied at a temperature of 70 ° C for hot pressing.