Spraying liquid of a nanometer carbon tube and the spraying method thereof

Abstract

This invention refers to spraying liquid for nano carbon pipe and spraying method, and preparing cathode electronic emission source layer of field emission display device by said method, which contains selecting adaptive and volatile spraying solvent, making nano carbon pipe suspended in it, adding nano carbon pipe and necessary fixing agent or additive to prepare into low viscosity spraying solution, spraying the nano carbon pipe solution on cathode conductive layer or cathode glass substrate by high pressure air, controlling the thickness by adjusting spraying times. Said invention can make the thickness homogenizing.

Description

technical field [0001] The present invention relates to a manufacturing technology of the cathode panel electron source layer of a field emission display (field emission display; FED), especially a kind of carbon nanotube spraying liquid and its spraying method. Electron emission source layer. Background technique [0002] The so-called field emission display of the present invention uses an electric field to make the cathode electron emitter (Cathodeelectron emitter) generate electrons, and the phosphor powder on the anode plate is excited by the electrons to make the phosphor powder generate photons. It is characterized by lightness, thinness, The size of the effective display area can be made according to the manufacturing process and product requirements, and there is no viewing angle problem like a flat liquid crystal display. [0003] The structure of a known field emission display 1a at least includes an anode 3a and a cathode 4a, and a barrier wall (rib) 53a is prov...

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Problems solved by technology

[0005] The manufacturing methods of this type of electron emission source layer containing carbon nanotubes include: a method of chemical vapor deposition to deposit carbon atoms on the cathode conductive layer of the cathode plate to form carbon nanotubes, although the current preparation process can Steadily grow carbon nanotubes of uniform length on the conductive layer, but the manufacturing cost is relatively high and the size of the field emission display cathode plate that can be produced is still below the size of small and medium-sized (20 o'clock), which is mostly limited

For this reason, the production of a kind of field emission display that can reduce production cost is to make each film layer of cathode and anode plate with thick film process (China Taiwan invention patent announcement number: 502395), provides the industry to provide an electron emission source with thick film production New ideas, wherein patents or periodicals for fabricating cathode electron emission sources by a screen printing process are constantly being proposed, however, even so, there are still some problems to be overcome for the electron emission source layer 60a printed by the screen printing method; First: Since the viscosity of the printing coating containing carbon nanotubes is usually at least 100,000 cps, in order to maintain the appearance and precision of the printed totem, in addition, the coating contains at least the necessary fixing agent (glass powder, etc.) and interface activity Agents and conductive agents (silver powder, etc.), especially in this high-viscosity environment to make carbon nanotubes uniformly dispersed, to avoid clustering of carbon nanotubes, which will affect the uniform distribution of electrons, so it must also be added chemically Necessary dispersant, the composition of the paint so produced is complex, the cost is increased, and the oxides produced at high temperature such as these solvents and surfactants during the sintering process are also more complex, so that subsequent manufacturers need to be more careful about whether these oxides are After sintering, it can be sintered to avoid poisoning carbon nanotubes and affecting the generation of electrons

Second: In order to cooperate with the screen printing process, limited by the basic requirements of the latex thickness of the screen cloth on the screen, the thickness of the produced coating 60a is still at least 10 μm on average, and the net knot on the screen cloth is also easy to cause the printed The surface thickness distribution deviation of the processed totem is usually 4-8 μm

Third: carbon nanotubes 62a have a good aspect ratio, and the ratio of carbon tube length to carbon tube diameter is usually more than 40. The manufacturing process needs to limit the length of carbon nanotubes, but because of the description in the second limitation, the thickness of the totem after screen printing reaches 10 μm, so it is easy to cause a large number of carbon nanotubes 62a to be coated with paint, even after sintering. Some carbon nanotubes are buried in the fixative or conductive material 61a, please refer to figure 2 As shown, the efficiency of electron generation is greatly reduced. For example, if an electron emission source layer containing multi-walled carbon nanotubes is set to be screen-printed, the current density under the electric field (E) 4V / μm is usually still 10mA / μm. cm 2 the following

[0006] In view of the fact that the fabrication of the cathode electron emission source layer of the known field emission display is to directly produce carbon nanotubes on the cathode electrode by the known chemical vapor deposition, the required equipment is expensive and the manufacturing process is complicated, or the electron emission source layer is produced by the screen printing method. The source layer is easy to make the thickness of the coating uneven, which affects the uniformity of luminescence and most of the carbon nanotubes are still buried inside the coating, which reduces the electron generation efficiency and current density.

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