WO2011108338A1 - Paste for electron emitting source, electron emitting source and electron emitting element each comprising same, and process for production of same - Google Patents

Abstract

Disclosed is a paste for an electron emitting source, which comprises (A) an electron emitting material, (B) a thermally degradable foaming agent and (C) a component capable of generating a shrinkage stress upon being thermally degraded, or comprises (A) an electron emitting material and (D) a thermal polymerization initiator that can act as a thermally degradable foaming agent and has an ethylenically unsaturated group. The above-mentioned paste composition can cause cracking on the surface of an electron emitting source. Therefore, the use of the paste composition enables the elimination of an activation treatment step for allowing carbon nanotubes to be exposed on the surface of the electron emitting source, and also enables the production of an electron emitting source that can emit electrons at a low voltage and can achieve homogeneous light emission.

Description

ELECTRON EMITTING SOURCE PASTE, ELECTRON EMITTING SOURCE AND ELECTRON EMITTING DEVICE USING THE SAME, AND METHOD FOR PRODUCING THEM

The present invention relates to an electron emission source paste, an electron emission source and an electron emission element using the paste, and a method of manufacturing the same.

Carbon-based materials such as carbon nanotubes, carbon nanofibers, carbon nanohorns, carbon nanocoils, and carbon nanowalls are not only excellent in physical and chemical durability, but also have sharp tip shapes suitable for field emission. And has a large aspect ratio. Therefore, various applied researches such as field emission displays (FED) using carbon-based materials as electron emission sources, liquid crystal backlight units (LCD-BLU) using field emission, lighting equipment, X-ray sources, etc. are prosperous. Has been done.

One method for producing an electron emission source using a carbon-based material is to paste a carbon-based material (for example, carbon nanotube) and apply it to a cathode substrate. In this method, as an example, a carbon nanotube-containing paste is formed on a cathode electrode, heat-treated, and then subjected to an activation treatment such as a tape peeling method or a laser irradiation method on the film surface. The paste material used in this method includes a carbon nanotube-containing paste containing glass powder (for example, see Patent Document 1), a carbonate-containing paste (for example, see Patent Document 2), or a metal carbonate-containing paste. (For example, refer to Patent Document 3). Moreover, in the paste using binder resin, binder resin is removed by baking. For this reason, a technique using a heat extinguisher material at a relatively low temperature has been proposed so that the residue does not easily remain (see, for example, Patent Document 4).

By the way, in the above process, the activation treatment is to expose the carbon nanotubes on the surface of the electron emission source in order to obtain good electron emission characteristics. However, if the activation process can be omitted, it can greatly contribute to further cost reduction. A porous electron emission source in which an electron emission material protrudes from the pore wall has been proposed as a material capable of obtaining good electron emission characteristics without performing brushing treatment (for example, Patent Document 5). reference). In this electron emission source, plastic particles such as polymethyl methacrylate are mixed in a carbon nanotube-containing paste, and the plastic particles are burned in a heat treatment process to form voids in the regions where the particles existed, thereby forming continuous holes. Is. Since the carbon nanotube protrudes from the hole wall, the activation process is unnecessary.

JP 2007-115675 A JP 2003-242898 A JP 2008-243789 A JP 2006-107835 A JP 2004-87304 A

However, the method described in Patent Document 5 has a problem that the voltage required for electron emission increases. There is also a problem that the light emission uniformity is not good.

The present invention pays attention to the above-mentioned problems, eliminates the activation treatment step of exposing the carbon nanotubes on the surface of the electron emission source, and enables the emission of electrons at a low voltage so that uniform emission can be obtained. It is another object of the present invention to provide an electron emission source using the same.

That is, the present invention is an electron emission source paste containing (A) an electron emission material, (B) a pyrolytic foaming agent, and (C) a component that generates shrinkage stress during thermal decomposition. Another aspect of the present invention is for an electron emission source comprising (A) an electron emission material, and (D) a thermal polymerization initiator that functions as a pyrolytic foaming agent and has an ethylenically unsaturated group. It is a paste.

According to the present invention, it is possible to omit the activation process step of exposing the carbon nanotubes on the surface of the electron emission source, so that it is possible to reduce the cost of equipment, materials, etc. required for the activation process step in the manufacture of the electron emission source. It is. Further, according to the present invention, it is possible to obtain an electron emission source capable of emitting electrons at a low voltage and obtaining uniform light emission even though activation processing is unnecessary.

Schematic cross-sectional view of the electron emission source of the present invention Electron micrograph of cracked electron emission source Electron micrograph of carbon nanotube protruding from crack surface in electron emission source of the present invention Optical micrograph of a cracked electron emission source Electron micrograph of carbon nanotube protruding from crack surface in electron emission source of the present invention Electron micrograph of cracked electron emission source

The electron emission source paste of the present invention contains (A) an electron emission material, (B) a pyrolytic foaming agent, and (C) a component that generates shrinkage stress during thermal decomposition. Another embodiment of the paste for an electron emission source according to the present invention includes (A) an electron emission material, and (D) a thermal polymerization initiator that functions as a pyrolytic foaming agent and has an ethylenically unsaturated group, Is included. The present invention also relates to an electron emission source and an electron emission device obtained by using the same, and a method for manufacturing them. By using the paste for an electron emission source of the present invention, it is possible to emit electrons at a low voltage without performing an activation treatment such as a tape peeling method or a laser irradiation method, excellent adhesion to the cathode electrode, and uniform. An electron emission source capable of emitting light can be obtained.

The reason why electrons can be emitted at a low voltage without performing the activation process is estimated as follows. In the following description, carbon nanotubes are taken as an example of (A) the electron emission material. However, as will be described later, the electron emission material is not limited to this, and the same applies to other materials.

When the electron emission source obtained by applying the electron emission source paste of the present invention on the substrate and heat-treating was observed, it was found that the electron emission source was cracked and the carbon nanotubes protruded from the crack. Therefore, it is considered that the electron emission can be obtained from the carbon nanotube protruding from the crack without performing the activation treatment. In addition, it is considered that in the process of generating cracks, a force that pulls out the carbon nanotubes in a direction substantially perpendicular to the cross section (crack surface) generated by the cracks inside the electron emission source works. Therefore, the protruding length of the carbon nanotube is increased and the aspect ratio is increased. As a result, electric field concentration is likely to occur in the carbon nanotube, and the voltage required for electron emission can be kept low. In order to emit electrons at a low voltage at a practical level, the protruding length of the carbon nanotube from the crack surface is preferably 0.5 μm or more, more preferably 1.0 μm or more, and 3.0 μm or more. Is more preferably 4.0 μm or more, and further preferably 5.0 μm or more. This can be achieved by using the paste for electron emission source of the present invention. If the length of the protruding carbon nanotube is such that it does not short-circuit with the gate electrode or anode electrode, the longer the protruding length of the carbon nanotube, the lower the voltage required for electron emission. Can do. Some projecting carbon nanotubes exist so as to bridge between cracks, but such ones may be included.

It is considered that (B) pyrolytic foaming agent contributes greatly to the occurrence of cracks. In the present specification, the pyrolytic foaming agent is a substance that thermally decomposes to release a gas and generate bubbles in the paste film for the electron emission source. It is considered that many cracks are likely to be generated by the bubbles being the starting point of cracks. As the number of cracks increases, the exposed electron emission material increases, so that the light emission uniformity is improved.

In addition, it is considered that (C) a component that generates shrinkage stress during thermal decomposition contributes greatly to the generation of the crack. It is considered that when a large shrinkage stress is applied to the electron emission source during the thermal decomposition due to the influence of the component (C), the generated crack grows.

(C) Examples of components that generate shrinkage stress during thermal decomposition include compounds such as metal salts, organometallic compounds, metal complexes, silane coupling agents, and titanium coupling agents. These are decomposed by heating. However, they are not completely burned down by combustion or decomposition like the plastic particles described in Patent Document 5, but have the characteristic of finally remaining as metal oxides or silicon compounds. In the following description of this specification, among the component (C), substances having characteristics that do not completely disappear even when heated to the paste firing temperature are collectively referred to as “residual compounds”. Since this residual compound shrinks during thermal decomposition, a shrinkage stress is generated in the paste film for the electron emission source, and a crack can be formed in the electron emission source after firing. Since the shrinkage stress is large, a carbon nanotube having a long protruding length can be obtained in the electron emission source when the width of the crack is large, and the voltage required for electron emission is reduced.

Also, as another example of the component (C) that generates shrinkage stress during thermal decomposition, a component combining a thermal polymerization initiator and a compound containing an ethylenically unsaturated group can be cited. The thermal polymerization initiator is decomposed by heating to generate radicals, and is used to crosslink the double bond portion of the ethylenically unsaturated group-containing compound. When the double bond portion is cross-linked, a large shrinkage stress is applied to the electron emission source during thermal decomposition. At that time, if there is a defect in the electron emission source, it is considered that a crack is generated starting from the defect and grows. As a result, the voltage required for electron emission can be lowered similarly to the “residual compound”.

By the way, it is considered that these components are decomposed and disappeared after the firing of the electron emission source paste. Thus, among the component (C), substances that disappear when heated to the paste firing temperature are collectively referred to as “disappearing crack generating agents”. In addition, the specific example of a vanishing crack generating agent is not restricted to these, What is necessary is just to show the same property.

In addition, each of the above components may be provided with a plurality of properties of gas release, cross-linking promotion, and ethylenically unsaturated group content with one substance. By doing so, the types of substances to be mixed can be reduced and the system can be simplified.

Specifically, as another embodiment of the component (C) that generates shrinkage stress during thermal decomposition, a thermal polymerization initiator containing an ethylenically unsaturated group can be mentioned. This is also included in the vanishing cracking agent. In addition, instead of using the component (B) and the component (C) separately, there is a case where a thermal polymerization initiator that functions as a thermal decomposition type foaming agent (D) and contains an ethylenically unsaturated group is used. . In these cases, the same effect can be obtained because the three elements are included in each paste. Note that (D) a thermal polymerization initiator that functions as a thermally decomposable foaming agent and contains an ethylenically unsaturated group is a thermal polymerization initiator that contains an ethylenically unsaturated group, and (B) It also serves as a pyrolytic foaming agent.

In addition, as another example of the disappearing crack generating agent, when using a substance that doubles as a pyrolytic foaming agent and a thermal polymerization initiator and an ethylenically unsaturated group-containing compound, or an ethylenically unsaturated group The case where the thermal decomposition type foaming agent and thermal polymerization initiator to contain are also mentioned. Since these have the role of a pyrolytic foaming agent, they may be used together with the component (B) or the component (B) may be omitted.

Other components (C) that generate shrinkage stress during thermal decomposition include siloxane materials and silicone materials.

The component (C) preferably generates a shrinkage stress below the firing temperature of the electron emission source paste. In a light emitting device application such as a general display or illumination, since inexpensive soda lime glass is used as a substrate, the component (C) preferably generates a shrinkage stress at a temperature of 100 ° C. or more and 500 ° C. or less. In addition, as a minimum, 150 degreeC or more is more preferable, and 200 degreeC or more is further more preferable. Moreover, as an upper limit, 450 degrees C or less is more preferable, and 400 degrees C or less is further more preferable. Any preferred lower limit can be combined with any preferred upper limit. When the temperature at which the component (C) generates contraction stress is within the above range, good cracks can be formed by a synergistic effect with the starting point generated by the pyrolytic foaming agent. Since the above-mentioned disappearing crack generating agent disappears after the firing of the electron emission source paste, it corresponds to a component that generates shrinkage stress at a temperature within the above range. Details of the residual compound will be described later.

In this specification, that a certain component generates shrinkage stress at a temperature of, for example, 100 ° C. or more and 500 ° C. or less means that the following condition is satisfied. First, thermogravimetric analysis by TGA (Thermogravimetric Analysis) is performed on the components in an inert gas atmosphere at a temperature rising rate of 10 ° C./min. The point at which the slope of the TGA curve obtained as a result changes negatively is defined as the thermal decomposition temperature of the component. And if the temperature range after the thermal decomposition temperature where the slope is negative is included in the range of 100 ° C. or more and 500 ° C. or less, the component generates shrinkage stress at a temperature of 100 ° C. or more and 500 ° C. or less. is there. This is because when the slope of the TGA curve after the thermal decomposition temperature is negative, that is, when the weight is reduced, it indicates that the material continues to undergo thermal decomposition.

In addition, in the case where either “residual compound” or “disappearing crack generator” is used as the component (C), finally, there is almost no organic residue remaining in the electron emission source, and good electron emission characteristics are obtained. Is preferable.

As described above, in the present invention, the generation of bubbles due to the pyrolytic foaming agent and the generation of shrinkage stress due to the residual compound or the extinguishing cracking agent occur stepwise or concurrently in the heat treatment process, and cracks occur. It is estimated that the generation and growth of

Among the above, more preferable embodiments of the paste for an electron emission source of the present invention are as follows.

(I) selected from the group consisting of (A) an electron emitting material, (B) a pyrolytic foaming agent, and (C) a metal salt, an organometallic compound, a metal complex, a silane coupling agent, and a titanium coupling agent. An electron emission source paste containing at least one substance.

(II) (A) An electron emission material, (B) a pyrolytic foaming agent, and (C) a paste for an electron emission source containing a thermal polymerization initiator and an ethylenically unsaturated group-containing compound as components.

(III) (A) an electron emission material, (B) a pyrolytic foaming agent, and (C) an electron emission source paste containing a thermal polymerization initiator containing an ethylenically unsaturated group as a component.

(IV) An electron emission source paste containing (A) an electron emission material, and (D) a thermal polymerization initiator that functions as a pyrolytic foaming agent and has an ethylenically unsaturated group.

On the other hand, when carbon nanotubes are projected from the wall of a continuous hole formed of plastic particles as described in Patent Document 5, since the shrinkage stress due to the burning of the plastic particles is weak, the protruding length of the carbon nanotubes is short. Thus, the aspect ratio becomes small. As a result, electric field concentration hardly occurs at the tip of the carbon nanotube, and the voltage required for electron emission increases.

The crack of the electron emission source of the present invention refers to a rift formed in the electron emission source as shown in FIG. 1 and having a width of 0.5 μm or more. The width of the crack means a measurement of the width of the crack in the surface portion of the electron emission source, as indicated by reference numeral 3 in FIG. The depth of the crack may or may not reach the cathode substrate.

As an example, FIG. 2 shows an electron micrograph of a crack on the surface of an electron emission source using basic magnesium carbonate as a residual compound and azodicarbonamide as a pyrolytic foaming agent, and an electron micrograph of a carbon nanotube protruding from the crack surface. Is shown in FIG. In addition, Fig. 4 shows an optical micrograph of a crack on the surface of an electron emission source using t-butyl peroxylaurate and tetrapropylene glycol dimethacrylate as a disappearing crack generator and azodicarbonamide as a pyrolytic foaming agent. An electron micrograph of the carbon nanotube protruding from the surface is shown in FIG.

Hereinafter, the paste for an electron emission source of the present invention will be described in more detail.

In general, (A) electron emission materials used in field emission displays and the like include metal materials typified by molybdenum, acicular carbon such as carbon nanotubes, carbon nanofibers, carbon nanohorns, carbon nanocoils, and carbon nanotwists, There are carbon-based materials represented by diamond, diamond-like carbon, graphite, carbon black, fullerene, and graphene. In the present invention, any of these can be used, but it is preferable to use acicular carbon because low voltage driving is possible due to low work function characteristics. Among the acicular carbons, carbon nanotubes are more preferable because of their high aspect ratio and good electrical emission characteristics. Hereinafter, an electron emission source paste using carbon nanotubes as representative of acicular carbon will be described as an example.

Carbon nanotubes may be single-walled or multi-walled, such as two or three, and any of them is preferably used. A mixture of carbon nanotubes having different numbers of layers may be used. Since the unpurified carbon nanotube powder may contain impurities such as amorphous carbon and catalytic metal, it can be used with increased purity by performing purification such as acid treatment. Further, in order to adjust the length of the carbon nanotube, the carbon nanotube powder may be pulverized by an ultrasonic wave, a ball mill, a bead mill or the like.

The content of the (A) electron-emitting material with respect to the whole electron-emitting source paste is preferably 0.1 to 20% by weight. Further, it is more preferably 0.1 to 10% by weight, and further preferably 0.1 to 5.0% by weight. When the content of the electron emission material is within the above range, good dispersibility, printability, and pattern formability of the electron emission source paste can be obtained.

(B) The pyrolytic foaming agent is preferably one that decomposes in the range of 50 to 300 ° C. to release gas, more preferably one that decomposes at 100 to 250 ° C. to release gas, and 150 to 250 ° C. What decomposes | disassembles and discharge | releases gas is still more preferable. By using a material that generates gas in the above temperature range, bubbles are not generated in the drying process when preparing the paste coating film for the electron emission source, and sufficient cracks can be generated in the heat treatment process during crack formation. it can. In this specification, for example, decomposing in the range of 50 to 300 ° C. means that the thermal decomposition temperature obtained by the TGA measurement is in the range of 50 to 300 ° C.

(B) Specific examples of the thermal decomposition type foaming agent include azo compounds such as azodicarbonamide and azobisisobutyronitrile, dinitrosopentamethylenetetramine, N, N′-dinitroso-N, N′-dimethylterephthalamide and the like. Nitroso compounds, p-toluenesulfonyl hydrazide, hydrazide compounds such as p, p'-oxybis (benzenesulfonylhydrazide), hydrazodicarbonamide, azide compounds such as p-toluenesulfonyl azide, hydrazones such as acetone-p-sulfonylhydrazone Compounds, melamine, urea, dicyanamide and the like can be mentioned, but are not limited thereto. Among these, when an azo compound, a nitroso compound, or a hydrazide compound is used, air bubbles are not generated in the drying process during the preparation of the paste film for the electron emission source, and the amount of gas released during thermal decomposition is large. This is particularly preferable because the effect of causing sufficient cracks in the heat treatment process during crack formation is great.

(B) The thermal decomposable foaming agent is preferably present as particles in the electron emission source paste because it can promote crack formation. Such thermally decomposable foaming agent particles preferably have an average particle size of 1.0 μm or more as a lower limit, more preferably 3.0 μm or more, and even more preferably 6.0 μm or more. . Moreover, as an upper limit, it is preferable that it is 25 micrometers or less, It is more preferable that it is 20 micrometers or less, It is further more preferable that it is 15 micrometers or less. Any preferred lower limit can be combined with any preferred upper limit. When the average particle size of the thermally decomposable foaming agent particles is not less than the above lower limit value, crack formation can be further promoted and the voltage required for electron emission can be lowered. Moreover, since it is less than the said upper limit and the surface unevenness | corrugation of an electron emission source can be reduced and a crack can be formed uniformly, favorable light emission uniformity can be obtained.

Here, the average particle diameter refers to a cumulative 50% particle diameter (D ₅₀ ). This represents the particle size at which the volume cumulative curve is 50% when the volume cumulative curve is determined with the total volume of one powder group as 100%. This is used as one of the parameters for evaluating the particle size distribution. The particle size distribution of the pyrolyzable foaming agent particles can be measured by a microtrack method (a method using a microtrack laser diffraction type particle size distribution measuring device manufactured by Nikkiso Co., Ltd.).

2. The content of the (B) pyrolytic foaming agent with respect to the whole paste for electron emission source is preferably 1.0% by weight or more, more preferably 2.0% by weight or more as a lower limit. It is more preferably 0% by weight or more, more preferably 5.0% by weight or more, and further preferably 10% by weight or more. Moreover, as an upper limit, it is preferable that it is 30 weight% or less, and it is more preferable that it is 25 weight% or less. Any preferred lower limit can be combined with any preferred upper limit. Further, the content of the pyrolyzable foaming agent with respect to the entire solid content excluding the solvent from the electron emission source paste is preferably 1.0% by weight or more as a lower limit, and preferably 3.0% by weight. More preferably, it is 5.0% by weight or more, more preferably 10% by weight or more. Moreover, as an upper limit, it is preferable that it is 50 weight% or less, It is more preferable that it is 40 weight% or less, It is further more preferable that it is 35 weight% or less. When the content of the pyrolytic foaming agent is within the above range, uniform bubbles can be formed in the electron emission source coating film.

(C) A specific example of a residual compound, which is an example of a component that generates shrinkage stress during thermal decomposition, will be described. In addition, since a thermal decomposition temperature changes with kinds of a residual compound, it is preferable to select the compound suitable for the temperature to be used suitably.

Metal salts refer to carbonates, sulfates, nitrates, hydroxide salts, bicarbonates, acetates, halide salts and the like. Examples of the metal carbonate include potassium carbonate, calcium carbonate, sodium carbonate, barium carbonate, magnesium carbonate, lithium carbonate, copper carbonate (II), iron carbonate (II), silver carbonate (I), nickel carbonate, hydrotalcite and the like. Can be used. Examples of the metal sulfate include zinc sulfate, aluminum sulfate, potassium sulfate, calcium sulfate, silver sulfate, potassium hydrogen sulfate, thallium sulfate, iron (II) sulfate, iron (III) sulfate, copper (I) sulfate, copper sulfate ( II), alums such as sodium sulfate, nickel sulfate, barium sulfate, magnesium sulfate, potassium alum and iron alum. Metal nitrates include magnesium nitrate, zinc nitrate, aluminum nitrate, uranyl nitrate, chlorine nitrate, potassium nitrate, calcium nitrate, silver nitrate, guanidine nitrate, cobalt nitrate, cobalt nitrate (II), cobalt nitrate (III), cesium nitrate, cerium nitrate Ammonium, iron nitrate, iron nitrate (II), iron nitrate (III), copper nitrate (II), sodium nitrate, lead nitrate (II), barium nitrate, rubidium nitrate and the like can be mentioned. Metal hydroxide salts include calcium hydroxide, magnesium hydroxide, manganese hydroxide, iron hydroxide (II), zinc hydroxide, copper hydroxide (II), lanthanum hydroxide, aluminum hydroxide, iron hydroxide ( III). Examples of the metal hydrogen carbonate include sodium hydrogen carbonate, potassium hydrogen carbonate, and calcium hydrogen carbonate. Metal halide salts are salts formed between metals such as alkali metals and alkaline earth metals and halogens such as fluorine, chlorine, bromine and iodine. For example, sodium fluoride, potassium fluoride, calcium fluoride, Examples include lithium fluoride, sodium chloride, potassium chloride, magnesium chloride, calcium chloride, lithium bromide, sodium bromide, potassium bromide, potassium iodide, and sodium iodide. Examples of the metal acetate include sodium acetate, potassium acetate, calcium acetate, magnesium acetate and the like. These metal salts can be used either as anhydrides or hydrates.

Examples of the organometallic compound include compounds having a metal-carbon bond. As metal elements constituting the organometallic compound, tin (Sn), indium (In), antimony (Sb), zinc (Zn), gold (Au), silver (Ag), copper (Cu), palladium (Pd), Examples include aluminum (Al), titanium (Ti), nickel (Ni), platinum (Pt), manganese (Mn), iron (Fe), cobalt (Co), chromium (Cr), and zirconium (Zn). In addition, groups included in the organic chain that forms an organometallic compound by combining with a metal element include acetyl group, alkyl group, alkoxy group, amino group, amide group, ester group, ether group, epoxy group, phenyl group, halogen There are groups. Specific examples of the organometallic compound include trimethylindium, triethylindium, tributoxyindium, trimethoxyindium, triethoxyindium, tetramethyltin, tetraethyltin, tetrabutyltin, tetramethoxytin, tetraethoxytin, tetrabutoxytin, Examples thereof include tetraphenyltin, triphenylantimony, triphenylantimony diacetate, triphenylantimony oxide, and triphenylantimony halide.

Examples of the metal complex include those having a structure in which a ligand is coordinated around the metal element mentioned in the organometallic compound. Examples of ligands that form metal complexes include amino groups, phosphino groups, carboxyl groups, carbonyl groups, thiol groups, hydroxyl groups, ether groups, ester groups, amide groups, cyano groups, halogen groups, thiocyano groups, pyridyl groups, Those having a lone pair of electrons such as a phenanthryl group. Specific examples of the ligand include triphenylphosphine, nitrate ion, halide ion, hydroxide ion, cyanide ion, thiocyan ion, ammonia, carbon monoxide, acetylacetonate, pyridine, ethylenediamine, bipyridine, phenanthroline. , BINAP, catecholate, terpyridine, ethylenediaminetetraacetic acid, porphyrin, cyclam, crown ethers and the like. Specific examples of the metal complex include an indium acetylacetonate complex, an indium ethylenediamine complex, an indium ethylenediaminetetraacetic acid complex, a tin acetylacetonate complex, a tin ethylenediamine complex, and a tin ethylenediaminetetraacetic acid.

Examples of the silane coupling agent include those having hydrolyzable silyl groups such as alkoxy groups, halogens, and acetoxy groups. Usually, an alkoxy group, particularly a methoxy group or an ethoxy group is preferably used. Moreover, as an organic functional group which a silane coupling agent has, an amino group, a methacryl group, an acrylic group, a vinyl group, an epoxy group, a mercapto group, an alkyl group, an allyl group, etc. can be mentioned. Specifically, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-aminopropyl Trimethoxysilane, γ-dibutylaminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, N-β- (N-vinylbenzylaminomethyl) -γ-aminopropyltrimethoxysilane hydrochloride, γ-methacryloxypropyl Trimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrichlorosilane, vinyltris (β-methoxyeth Xy) silane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, n-propyltrimethoxysilane, isobutyltrimethoxysilane, n-hexyltrimethoxysilane, n-decyl Examples include trimethoxysilane, n-hexadecyltrimethoxysilane, phenyltrimethoxysilane, and diphenyldimethoxysilane. In the present invention, one kind selected from these coupling agents may be used alone, or two or more kinds may be used in combination. Moreover, you may use the self-condensate using the said coupling agent 1 type, and the heterogeneous condensate which combined 2 or more types.

Examples of the titanium coupling agent include those obtained by replacing the silane portion of the silane coupling agent with titanium.

Of these, metal salts are preferably used. An electron emission source obtained by using an electron emission source paste containing a metal salt has a large crack size generated in the electron emission source, and a carbon nanotube has a long protruding length. In addition, low voltage driving is possible and light emission uniformity is good. This is presumably because the shrinkage stress generated during the thermal decomposition of the metal salt, which is an inorganic component, is larger than the contraction stress generated during the thermal decomposition of the organic component. Of these, metal carbonates, metal nitrates or metal sulfates are preferred in that they are thermally decomposed in a low temperature range of 100 to 500 ° C. Of these, metal carbonates are more preferred because they are most susceptible to cracking. Furthermore, when a metal carbonate containing magnesium is used, MgO generated by thermal decomposition works as a secondary electron emission material, and the electron emission source can be driven at a low voltage, which is particularly preferable.

The average particle size of the residual compound is preferably 0.5 to 10 μm. When the average particle size of the residual compound is 0.5 μm or more, cracks can be generated by the shrinkage stress generated during thermal decomposition, and when it is 10 μm or less, the emitter surface unevenness is reduced and good emission uniformity is obtained. Obtainable. Here, the average particle diameter means a cumulative 50% particle diameter (D ₅₀ ), and can be measured by the same method as in the case of the pyrolytic foaming agent particles.

The content of the residual compound with respect to the entire paste for the electron emission source is preferably 1.0% by weight or more as a lower limit, more preferably 5.0% by weight or more, and 10% by weight or more. Is more preferable. Moreover, as an upper limit, it is preferable that it is 30 weight% or less, and it is more preferable that it is 25 weight% or less. Any preferred lower limit can be combined with any preferred upper limit. Further, the content of the residual compound with respect to the entire solid content excluding the solvent from the paste for the electron emission source is preferably 1.0% by weight or more as a lower limit, and more preferably 5.0% by weight or more. Preferably, it is 10% by weight or more. Moreover, as an upper limit, it is preferable that it is 60 weight% or less, It is more preferable that it is 50 weight% or less, It is more preferable that it is 40 weight% or less, It is further more preferable that it is 35 weight% or less. When the content of the residual compound is within the above range, uniform cracks can be formed in the electron emission source coating film.

(C) A specific example of the vanishing cracking agent, which is an example of a component that generates shrinkage stress during thermal decomposition, will be described.

Examples of the thermal polymerization initiator include 2,2′-azobis (2-methylpropionitrile), 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane) in the azo series. -1-carbonitrile), 1-[(1-cyano-1-methylethyl) azo] formamide (2- (carbamoylazo) isobutyronitrile), 2,2′-azobis {2-methyl-N- [2 -(1-hydroxybutyl)] propionamide}, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], 2,2′-azobis [N- (2-propenyl) -2-methylpropionamide], 2,2′-azobis (N-butyl-2-methylpropionamide), 2,2′-azobis (N-cyclohexyl-2-methylpropionamide), 2 2'-azobis (2,4,4-trimethylpentane) (azodi -t- octane) and the like. In the case of peroxides, t-butyl peroxypivalate, t-hexyl peroxy-2-ethylhexanoate, 1,1-bis (t-butylperoxy) -2-methylcyclohexane, 1,1 -Bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) -3,3 5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis (4,4-dibutylperoxycyclohexyl) propane, 1,1-bis (t-butylperoxy) cyclododecane , T-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-to Methyl hexanoate, t-butyl peroxylaurate, dibenzoyl peroxide, 2,5-dimethyl-2,5-di (m-toluoyl peroxy) hexane, t-butyl peroxyisopropyl monocarbonate, t- Butyl peroxy-2-ethylhexyl monocarbonate, t-hexyl peroxybenzoate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butyl peroxyacetate, 2,2-bis (t- Butylperoxy) butane, t-butylperoxybenzoate, n-butyl-4,4-bis (t-butylperoxy) valerate, di-t-butylperoxyisophthalate, α, α'-bis (t- Butylperoxy) diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2, - di (t-butylperoxy) hexane, and the like t-butyl cumyl peroxide and the like.

Examples of the component containing an ethylenically unsaturated group include a vinyl group, an allyl group, an acryloyl group, and a methacryloyl group. In particular, it preferably has an acryloyl group or a methacryloyl group.

Specific examples of the compound having an acryloyl group or a methacryloyl group include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-pentyl acrylate, Examples include allyl acrylate, benzyl acrylate, butoxyethyl acrylate, butoxytriethylene glycol acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, 2-ethylhexyl acrylate, and tetrapropylene glycol dimethacrylate.

The component having an ethylenically unsaturated group is a monofunctional monomer having one ethylenically unsaturated group in one molecule, and the polyfunctional monomer having two or more is a bifunctional monomer or trifunctional. Monomers, tetrafunctional monomers, pentafunctional monomers, hexafunctional monomers and the like can be mentioned, and monofunctional or bifunctional monomers can be preferably used from the viewpoint of good thermal decomposability.

As a specific example of the monofunctional monomer, (meth) acrylic acid or (meth) acrylic acid ester is used. Specifically, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetate or their anhydrides, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-pentyl acrylate, sec-butyl acrylate, isobutyl acrylate, n-butyl acrylate, tert-butyl acrylate, 2-n-butoxyethyl acrylate, butoxyethylene glycol acrylate, butoxytriethylene glycol acrylate, 2-ethylhexyl acrylate, glycerol acrylate, heptadecafluorodecyl acrylate , 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-methoxyethyl acrylate, isodex Acrylate, isooctyl acrylate, lauryl acrylate, methoxyethylene glycol acrylate, methoxydiethylene glycol acrylate, octafluoroethyl acrylate, trifluoroethyl acrylate, stearyl acrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, ditrimethylolpropane Tetraacrylate, glycerol acrylate, neopentyl glycol acrylate, propylene glycol acrylate, acrylamide, aminoethyl acrylate, styrene, α-methylstyrene, allyl acrylate, benzyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate Examples thereof include compounds in which some or all of the acrylates in the molecule of the above-mentioned compounds are changed to methacrylates.

Specific examples of the bifunctional monomer include aromatic divinyl monomers such as divinylbenzene, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6 -Polyalkylene glycol di (meta) such as alkylene glycol di (meth) acrylate such as hexanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate ) Acrylate, urethane di (meth) acrylate, or polyester di (meth) acrylate.

In the present invention, the component containing an ethylenically unsaturated group is not limited to these. These can be used alone or in combination of two or more.

Examples of the thermal polymerization initiator containing an ethylenically unsaturated group include a thermal polymerization initiator containing a vinyl group, an allyl group, an acryloyl group, and a methacryloyl group. Specifically, for example, diallyl peroxydicarbonate, bis (2-methyl-2-propenyl) peroxydicarbonate, bis (2-ethyl-2-propenyl) peroxydicarbonate, bis (1-methyl-2 -Propenyl) peroxydicarbonate, bis (2-methyl-2-butenyl) peroxydicarbonate, bis (2-methyl-2-propenyloxyethylperoxy) dicarbonate and the like.

The substance that has the properties of both a pyrolytic foaming agent and a thermal polymerization initiator serves to promote crosslinking by heat. Examples of such components include azo-based thermal polymerization initiators. Specifically, for example, 2,2′-azobis (2-methylpropionitrile), 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile) , 1-[(1-cyano-1-methylethyl) azo] formamide (2- (carbamoylazo) isobutyronitrile), 2,2′-azobis {2-methyl-N- [2- (1-hydroxybutyl) )]-Propionamide}, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], 2,2′-azobis [N- (2-propenyl) -2-methylpropion Amido], 2,2′-azobis (N-butyl-2-methylpropionamide), 2,2′-azobis (N-cyclohexyl-2-methylpropionamide), 2,2′-a Bis (2,4,4-trimethylpentane) (azodi -t- octane) and the like.

Examples of the thermally decomposable foaming agent containing an ethylenically unsaturated group include an azo compound containing a vinyl group, an allyl group, an acryloyl group, and a methacryloyl group, a nitroso compound, and a hydrazide compound. Specific examples include phenylazoacrylanilide, N-methyl-N-nitrosoallylamine, homoallyl hydrazide and the like.

(D) The thermal polymerization initiator that functions as a thermally decomposable foaming agent and contains an ethylenically unsaturated group is preferably one that decomposes in the range of 50 to 300 ° C. and releases a gas, and is 100 to 250 ° C. Those that decompose and release a gas are more preferable, and those that decompose at 150 to 250 ° C. to release a gas are more preferable. Such a compound is preferably an azo compound, a nitroso compound, a hydrazide compound, an azide compound, or a hydrazone compound, and a thermal polymerization initiator containing an ethylenically unsaturated group. Specific examples include 2,2'-azobis [N- (2-propenyl) -2-methylpropionamide] which is an azo-based thermal polymerization initiator and contains an ethylenically unsaturated group.

(D) The thermal polymerization initiator that functions as a pyrolytic foaming agent and contains an ethylenically unsaturated group preferably has an average particle size of 1.0 μm or more as a lower limit, and 3.0 μm or more. It is more preferable that it is 6.0 μm or more. Moreover, as an upper limit, it is preferable that it is 25 micrometers or less, It is more preferable that it is 20 micrometers or less, It is further more preferable that it is 15 micrometers or less. Any preferred lower limit can be combined with any preferred upper limit. When the average particle diameter of the thermal polymerization initiator that functions as the (D) pyrolytic foaming agent and contains an ethylenically unsaturated group is equal to or greater than the lower limit, crack formation is further promoted, and electrons The voltage required for discharge can be lowered. Moreover, since it is less than the said upper limit and the surface unevenness | corrugation of an electron emission source can be reduced and a crack can be formed uniformly, favorable light emission uniformity can be obtained.

(C) A disappearing crack generator and a residual compound may be used in combination. In particular, it is more preferable to use a combination of one or several types selected from the group consisting of metal salts, organometallic compounds, metal complexes, silane coupling agents, and titanium coupling agents. By further containing these components, cracks generated when the electron emission source paste is heat-treated increase, and carbon nanotubes having a long protruding length increase. Therefore, an electron emission source with even better electron emission characteristics can be obtained.

The content of the extinguishing crack generating agent with respect to the entire paste for electron emission source is preferably 1.0% by weight or more, more preferably 3.0% by weight or more as a lower limit, and 5.0% by weight. More preferably, it is the above. Moreover, as an upper limit, it is preferable that it is 50 weight% or less, It is more preferable that it is 40 weight% or less, It is further more preferable that it is 30 weight% or less. Any preferred lower limit can be combined with any preferred upper limit. Further, the content of the extinguishing crack generating agent with respect to the entire solid content excluding the solvent from the paste for electron emission source is preferably 1.0% by weight or more as a lower limit, and 5.0% by weight or more. Is more preferable, and it is further more preferable that it is 10 weight% or more. Moreover, as an upper limit, it is preferable that it is 60 weight% or less, It is more preferable that it is 50 weight% or less, It is more preferable that it is 40 weight% or less, It is further more preferable that it is 30 weight% or less. A uniform crack can be formed in an electron emission source coating film as content of a vanishing crack generating agent exists in the said range.

The electron emission source paste of the present invention can contain an inorganic powder. Any inorganic powder can be used as long as it plays a role as an adhesive. Considering that the heat resistance of the carbon nanotube is 500 to 600 ° C. and using soda lime glass (softening point of about 500 ° C.) as the substrate glass, the sintering temperature of the inorganic powder is preferably 500 ° C. or less, and 450 ° C. More preferred are: By using the inorganic powder having the sintering temperature, it is possible to suppress burning of the carbon nanotubes and to use an inexpensive substrate glass such as soda lime glass. Specific examples of such inorganic powders include metal powders such as silver, copper, nickel, alloys, and solder, glass powders, or a mixture thereof. Glass powder is preferably used in the paste for electron emission source of the present invention because the metal powder may promote the burning of carbon nanotubes by catalytic action.

Since the glass softening point representing the sintering temperature of the glass powder varies depending on the glass composition, it can be controlled by selecting the glass composition. As the glass powder contained in the electron emission source paste of the present invention, Bi ₂ O ₃ glass, alkali glass, SnO—P ₂ O ₅ glass, SnO—B ₂ O ₃ glass and the like are preferably used. Use of the glass powder is preferable because the glass softening point can be controlled in the range of 300 ° C to 450 ° C.

The ratio of the electron emission material (A) contained in the electron emission source paste to the inorganic powder is preferably 200 to 8000 parts by weight of the inorganic powder with respect to 100 parts by weight of the electron emission material. If it is 200 parts by weight or more, sufficient adhesiveness can be obtained, and if it is 8000 parts by weight or less, the electron emission source paste has an appropriate viscosity.

The average particle size of the inorganic powder is preferably 2.0 μm or less, and more preferably 1.0 μm or less. When the average particle diameter of the inorganic powder is 2.0 μm or less, it is possible to obtain the formability of a fine electron emission source pattern and the adhesion between the electron emission source and the cathode electrode. Here, the average particle diameter means a cumulative 50% particle diameter (D ₅₀ ), and can be measured by the same method as in the case of the pyrolytic foaming agent particles.

The electron emission source paste of the present invention preferably contains conductive particles. When the paste for the electron emission source contains conductive particles, the resistance value inside the electron emission source is lowered, and the electron emission from the electron emission source can be performed at a lower voltage. The conductive particles are not particularly limited as long as they are conductive, but are preferably particles containing a conductive oxide, or particles in which a conductive material is coated on part or all of the oxide surface. . This is because metal has high catalytic activity and may deteriorate the electron-emitting material when the temperature becomes high due to firing or electron emission. As the conductive oxide, indium tin oxide (ITO), tin oxide, zinc oxide and the like are preferable. Moreover, what coated ITO, tin oxide, zinc oxide, gold | metal | money, platinum, silver, copper, palladium, nickel, iron, cobalt etc. in part or all of oxide surfaces, such as a titanium oxide and a silicon oxide, is also preferable. Also in this case, the conductive material is preferably a conductive oxide such as ITO, tin oxide, or zinc oxide.

When conductive particles are contained in the electron emission source paste, the content thereof is preferably 0.1 to 100 parts by weight of conductive particles with respect to 1.0 part by weight of the electron emission material. More preferably, it is ˜50 parts by weight. When the content of the conductive particles is within the above range, it is particularly preferable because the electrical contact between the electron emission material and the cathode electrode becomes better.

The average particle size of the conductive particles is preferably from 0.1 to 1.0 μm, more preferably from 0.1 to 0.6 μm. If the average particle size of the conductive particles is within the above range, the uniformity of the resistance value inside the electron emission source is good and further the surface flatness is obtained, so that uniform electron emission from the surface can be achieved at a low voltage. Obtainable. Here, the average particle diameter means a cumulative 50% particle diameter (D ₅₀ ), and can be measured by the same method as in the case of the pyrolytic foaming agent particles.

The electron emission source paste of the present invention can contain an organic binder, a solvent, and a dispersant in order to impart pattern forming performance by a general printing method such as screen printing or inkjet coating. Furthermore, additives such as plasticizers, thickeners, antioxidants, organic or inorganic precipitation inhibitors and leveling agents may be included to improve paste characteristics. In addition, when pattern formation is performed by photolithography, photosensitivity is imparted by including a resin having an ethylenically unsaturated group, a photocurable monomer, a photopolymerization initiator, an ultraviolet absorber, a polymerization inhibitor, a sensitizer, and the like. can do.

Organic binders include cellulose resins (ethyl cellulose, methyl cellulose, nitrocellulose, acetyl cellulose, cellulose propionate, hydroxypropyl cellulose, butyl cellulose, benzyl cellulose, modified cellulose, etc.), acrylic resins (acrylic acid, methacrylic acid, methyl Acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-butyl acrylate, n-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, 2-hydroxyethyl acrylate, 2 -Hydroxyethyl methacrylate, 2-hydroxypropylene Relate, 2-hydroxypropyl methacrylate, benzyl acrylate, benzyl methacrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate, isobornyl acrylate, isobornyl methacrylate, glycidyl methacrylate, styrene, α-methylstyrene, 3-methylstyrene, 4-methyl Polymer consisting of at least one of monomers such as styrene, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile), ethylene-vinyl acetate copolymer resin, polyvinyl butyral, polyvinyl alcohol, propylene glycol, urethane resin, melamine Resins, phenol resins, alkyd resins and the like can be mentioned.

The solvent is preferably a solvent that dissolves an organic component such as a binder resin. For example, polyhydric alcohols such as diol and triol typified by ethylene glycol and glycerin, compounds obtained by etherification and / or esterification of alcohol (ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether, ethylene glycol alkyl ether acetate, diethylene glycol monoacetate) Alkyl ether acetate, diethylene glycol dialkyl ether, propylene glycol monoalkyl ether, propylene glycol dialkyl ether, propylene glycol alkyl ether acetate) and the like. More specifically, terpineol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, ethylene glycol dipropyl ether, diethylene glycol dibutyl ether, methyl cellosolve acetate , Ethyl cellosolve acetate, propyl cellosolve acetate, butyl cellosolve acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, 2,2,4-trimethyl-1,3-pentanediol monoisobutylene DOO, organic solvent mixture containing one or more of such or these butyl carbitol acetate is used.

The method for producing the paste for an electron emission source of the present invention includes an electron emission material, a pyrolytic foaming agent, a component that generates shrinkage stress during thermal decomposition, and further, if necessary, an inorganic powder, an organic binder, a dispersant, a solvent, etc. Are added to the desired composition, and then uniformly dispersed using a kneading machine such as a ball mill, a planetary ball mill, a bead mill, an ultra apex mill, a mixer, a three-roller, a homogenizer, or ultrasonic waves. It is done. The paste viscosity is adjusted depending on the addition ratio of glass powder, thickener, solvent, plasticizer, suspending agent, and the like, but the viscosity range required for the paste varies depending on the printing technique, so the paste viscosity is adjusted as appropriate. For example, when a pattern is formed by a slit die coater or a screen printing method, the viscosity is preferably 2 to 200 Pa · s. In the case of forming a pattern by a spin coating method, a spray method or an ink jet method, the viscosity is preferably 0.001 to 5 Pa · s.

Hereinafter, an electron emission source and an electron emission device manufacturing method using the electron emission source paste of the present invention will be described. Note that other known methods may be used for manufacturing the electron-emitting source and the electron-emitting device, and the method is not limited to the manufacturing method described later.

First, a method for manufacturing an electron emission source will be described. As will be described below, the electron emission source can be obtained by forming a pattern using the electron emission source paste of the present invention on a substrate and then baking it. First, an electron emission source pattern is formed on a substrate using the electron emission source paste of the present invention. As the substrate, any substrate that fixes the electron emission source may be used, and examples thereof include a glass substrate, a ceramic substrate, a metal substrate, and a film substrate. A conductive film is preferably formed on the substrate. As a method for forming the pattern of the electron emission source on the substrate, a printing method such as a general screen printing method or an ink jet method is preferably used. Further, it is preferable to use an electron emission source paste imparted with photosensitivity because a fine electron emission source pattern can be collectively formed by photolithography. Specifically, the electron emission source paste imparted with the photosensitivity of the present invention is printed on the substrate by a screen printing method or a slit die coater, and then dried by a hot air dryer to form a coating film of the electron emission source paste. Get. The coating film may be irradiated with ultraviolet rays through a photomask from the upper surface (electron emission source paste side), and then developed with an alkali developer or an organic developer to form an electron emission source pattern. Next, the pattern of the electron emission source is baked. The firing is performed in air or an inert gas atmosphere such as nitrogen, and the firing temperature is 400 to 500 ° C.

Next, a method for manufacturing an electron-emitting device will be described. The electron-emitting device can be obtained by forming an electron emission source made of the paste for an electron emission source of the present invention on a cathode electrode to produce a back plate, and facing an anode electrode and a front plate having a phosphor. . Hereinafter, a method for manufacturing a diode-type electron-emitting device and a method for manufacturing a triode-type electron-emitting device will be described in detail.

In the manufacturing method of the diode-type electron-emitting device, first, a cathode electrode is formed on a glass substrate. As the cathode electrode, a conductive film such as ITO or chromium can be formed on the glass substrate by sputtering or the like. On the cathode electrode, an electron emission source is prepared by the above-described method using the electron emission source paste of the present invention, and a back plate for a diode-type electron emission element is obtained. Next, an anode electrode is formed on the glass substrate. As the anode electrode, a transparent conductive film such as ITO can be formed on the glass substrate by sputtering or the like. A phosphor is printed on the anode electrode formed on the glass substrate to obtain a front plate of the diode-type electron-emitting device. The back plate and front plate for the diode-type electron-emitting device are bonded together with a spacer so that the electron emission source and the phosphor face each other, and evacuated by an exhaust pipe connected to the container, so that the internal vacuum degree is 1 × A diode-type electron-emitting device can be obtained by fusing in a state of 10 ⁻³ Pa or less. In order to confirm the electron emission state, by supplying a voltage of 1 to 5 kV to the anode electrode, electrons are emitted from the carbon nanotubes and collide with the phosphor, whereby the phosphor can emit light.

In the method for producing a triode type electron-emitting device, first, a cathode electrode is produced on a glass substrate. As the cathode electrode, a conductive film such as ITO or chromium can be formed by sputtering or the like. Next, an insulating layer is formed on the cathode electrode. The insulating layer can be formed with an insulating material having a thickness of about 3 to 20 μm by a printing method or a vacuum evaporation method. Next, a gate electrode layer is formed over the insulating layer. The gate electrode layer can be obtained by forming a conductive film such as chromium by a vacuum deposition method or the like. Next, an emitter hole is formed in the insulating layer. The emitter hole is formed by first applying a resist material on the gate electrode by a spin coater method, drying, irradiating ultraviolet rays through a photomask, transferring the pattern, and then developing with an alkali developer or the like. By etching the gate electrode and the insulating layer from the portion opened by development, an emitter hole can be formed in the insulating layer. Next, an electron emission source is produced in the emitter hole by using the electron emission source paste of the present invention by the above-described method, and a back plate for a triode type electron emission device is obtained. Next, an anode electrode is formed on the glass substrate. As the anode electrode, a transparent conductive film such as ITO can be formed on the glass substrate by sputtering or the like. A phosphor is printed on the anode electrode formed on the glass substrate to obtain a front plate of the triode type electron-emitting device. The back plate and the front plate for the triode type electron-emitting device are bonded together with a spacer so that the electron emission source and the phosphor face each other, and evacuated by an exhaust pipe connected to the container. A diode-type electron-emitting device can be obtained by fusing in a state of 0 × 10 ⁻³ Pa or less. In order to confirm the electron emission state, by supplying a voltage of 1 to 5 kV to the anode electrode and a voltage of 20 to 150 V to the gate electrode, electrons are emitted from the carbon nanotubes and collide with the phosphor to obtain light emission of the phosphor. Can do.

An electron emission source produced using the paste for an electron emission source of the present invention can be obtained by, for example, an energy dispersive X-ray analyzer (EMAXＡENERGY EX-250) combined with a scanning electron microscope (S-4800). Its composition can be analyzed. As a specific analysis method using the above-described method, first, an electron emission source is observed using a scanning electron microscope, so that, for example, an electron-emitting material having a fiber-like structure, a particle-like conductive property, and the like from the shape of each component. The glass component as a functional oxide and a matrix can be generally specified. Further, by using an energy dispersive X-ray analyzer, elemental analysis of each component can be performed and the composition can be specified. However, the analysis of the electron emission source may be any method as long as the composition of the electron emission source can be specified, and is not limited to these methods.

Furthermore, by using the electron emission source paste of the present invention, for example, the following electron emission source can be produced. An electron emission source having a crack, in which an electron emission material protrudes into the crack, wherein the minimum length of the electron emission source is 1.0 mm or less, and the ratio of the crack portion in the electron emission source is 10% That is the electron emission source.

Such an electron emission source having cracks formed at a high density even though it is minute as described above is an electron emission source capable of achieving both high resolution and good electron emission characteristics when used as a device.

The planar shape of the electron emission source is not particularly limited, but is square, rectangular, parallelogram, trapezoid, circle, triangle, quadrangle, ellipse, sector, regular n-gon (n is 5 or more) in terms of good emission uniformity. Integers) or shapes according to them are preferably used.

The minimum length of the electron emission source is obtained by the following method. First, when the electron emission source is viewed from a direction substantially perpendicular to the substrate, it is considered to be a plane figure substantially parallel to the substrate. At this time, the center of gravity of the electron emission source is determined in accordance with a method for obtaining the center of gravity of a general plane figure. Further, a straight line is selected so that the distance between two points where the straight line passing through the center of gravity and the plane figure of the electron emission source intersect is the shortest. The length between the intersections at that time is defined as the shortest length of the electron emission source. The minimum length of the electron emission source required by this method is equal to the length of one side when the plane figure is square, equal to the length of the short side when rectangular, and equal to the length of diameter when circular. . The shortest length of the electron emission source is preferably 1.0 mm or less, more preferably 0.5 mm or less, and further preferably 0.3 mm or less. When the minimum length of the electron emission source is within the above range, a device with higher resolution can be obtained.

Next, the ratio of cracks in the electron emission source is obtained by the following method. When the electron emission source is considered to be a plane figure in the same manner as in the above method, the area where cracks occupy the area of the entire plane figure is expressed as a percentage (%) as the “ratio of cracks in the electron emission source”. As an example of the area calculation method, a plane figure of an electron emission source is taken in as image data of a scanning electron microscope or an optical microscope, and is calculated using general image processing software, for example, MATLAB (manufactured by MathWorks). Can do. The ratio of cracks in the electron emission source is preferably 10% or more, more preferably 15% or more, and further preferably 20% or more. When the ratio of the crack portion in the electron emission source is within the above range, an electron emission source having a low voltage required for electron emission and excellent light emission uniformity can be obtained.

Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to this. The electron emission materials, inorganic powders and organic components used in the examples and comparative examples, and the evaluation methods of the evaluation items in the examples and comparative examples are as follows.

(A) component <electron emission material>
Carbon nanotube 1: Double-walled carbon nanotube (manufactured by Shenzhen Nanotechport)
Carbon nanotube 2: Multi-walled carbon nanotube (manufactured by Toray Industries, Inc.).

Component (B) <Pyrolytic foaming agent>
Thermal Decomposable Foaming Agent 1: Azodicarbonamide Decomposition temperature 200 ° C. (Sankyo Kasei Co., Ltd. 'Cermic C121', average particle size 12 μm)
Thermal decomposition type foaming agent 2: Dinitrosopentamethylenetetramine Decomposition temperature 205 ° C. (Sankyo Kasei Co., Ltd., “Cermic A” was subjected to dry centrifugal classification with Nisshin Engineering Co., Ltd. “Turbo Classifier”, average particle size 15 μm )
Thermal decomposable foaming agent 3: p, p'-oxybis (benzenesulfonylhydrazide) Decomposition temperature 160 ° C (Sankyo Kasei Co., Ltd. 'Cermic S', average particle size 13 µm)
Pyrolytic foaming agent 1 with an average particle size of 1.0 μm (Sankyo Kasei Co., Ltd. 'Cermic C-2' was subjected to dry centrifugal classification with Nisshin Engineering Co., Ltd. 'Turbo Classifier')
Thermally decomposable foaming agent 1 with an average particle size of 6.0 μm (Sankyo Kasei Co., Ltd. 'Cermic CE')
Thermally decomposable foaming agent 1 with an average particle size of 18 μm (Sankyo Kasei Co., Ltd. 'Cermic C-191')
A product having an average particle size of 25 μm of the pyrolytic foaming agent 1 (Yewa Kasei Kogyo Co., Ltd., “Binihol AC # K3”).

(C) component <residual compound>
Metal carbonate 1: basic magnesium carbonate, heavy (Wako Pure Chemical Industries, Ltd.) (thermal decomposition temperature: 250 ° C, 400 ° C)
Metal carbonate 2: Sodium carbonate decahydrate (Wako Pure Chemical Industries, Ltd.) (thermal decomposition temperature: 200 ° C.)
Metal carbonate 3: Sodium hydrogen carbonate (Wako Pure Chemical Industries, Ltd.) (thermal decomposition temperature: 300 ° C.)
Metal nitrate: Magnesium nitrate hexahydrate (Wako Pure Chemical Industries, Ltd.) (thermal decomposition temperature: 400 ° C)
Metal sulfate: Magnesium sulfate heptahydrate (Wako Pure Chemical Industries, Ltd.) (thermal decomposition temperature: 200 ° C)
Metal hydroxide salt: Magnesium hydroxide (Wako Pure Chemical Industries, Ltd.) (thermal decomposition temperature: 350 ° C)
Organometallic compound: Nikka Octix Tin (Nippon Chemical Industry Co., Ltd.) (thermal decomposition temperature: 350 ° C)
Metal complex 1: Nasem tin (Nippon Chemical Industry Co., Ltd.) (thermal decomposition temperature: 200 ° C)
Metal complex 2: bis (acetylacetonato) zinc (II) (Nippon Chemical Industry Co., Ltd.) (thermal decomposition temperature: 150 ° C.)
Silane coupling agent: “KBE-04” (Shin-Etsu Silicone Co., Ltd.) (thermal decomposition temperature: 150 ° C.)
Titanium coupling agent: “Orga Tix TA30” (Matsumoto Fine Chemical Co., Ltd.) (thermal decomposition temperature: 150 ° C.).

<Thermal polymerization initiator>
Thermal polymerization initiator 1: t-butyl peroxylaurate 10 hours half-life temperature 98 ° C
Thermal polymerization initiator 2: t-ethylperoxy-2-ethylhexanoate 10 hours half-life temperature 72 ° C
Thermal polymerization initiator 3: Dibenzoyl peroxide 10 hours half-life temperature 74 ° C.

<Ethylenically unsaturated group-containing compound>
Ethylenically unsaturated group-containing compound 1: Tetrapropylene glycol dimethacrylate Ethylenically unsaturated group-containing compound 2: Cyclohexyl acrylate Ethylenically unsaturated group-containing compound 3: n-butyl acrylate

<Ethylenically unsaturated group-containing thermal polymerization initiator>
Ethylenically unsaturated group-containing thermal polymerization initiator 1: bis (2-methyl-2-propenyl) peroxydicarbonate 10 hours half-life temperature 39 ° C
Ethylenically unsaturated group-containing thermal polymerization initiator 2: diallyl peroxydicarbonate 10 hours half-life temperature 39 ° C
Ethylenically unsaturated group-containing thermal polymerization initiator 3: bis (2-methyl-2-propenyloxyethylperoxy) dicarbonate 10 hours half-life temperature 44 ° C.

Component (D) <Pyrolytic foaming agent and ethylenically unsaturated group-containing thermal polymerization initiator>
2,2′-Azobis [N- (2-propenyl) -2-methylpropionamide] 10 hour half-life temperature 96 ° C.

Other ingredients <Inorganic ingredients>
Glass powder: SnO—P ₂ O ₅ glass “KF9079” (manufactured by Asahi Glass Co., Ltd.), softening point 340 ° C., average particle size 0.2 μm
Conductive particles: White conductive powder “ET-500W” (coated with SnO ₂ / Sb conductive layer using spherical titanium oxide as a core, manufactured by Ishihara Sangyo Co., Ltd.), specific surface area 6.9 m ² / g, The density is 4.6 g / cm ³ and the average particle size is 0.2 μm.

<Organic component>
Binder: Poly (iso-butyl methacrylate) fine powder, [h] = 0.60 (manufactured by Wako Pure Chemical Industries, Ltd.)
Polystyrene particles: Megabeads NIST traceable particle size standard particles, 10.0 μm
Solvent: Terpineol (manufactured by Wako Pure Chemical Industries, Ltd.).

Evaluation method <Observation of electron emission source surface crack width>
The presence or absence of cracks on the surface of the electron emission source was confirmed using an optical microscope. Further, the electron emission source was observed with a scanning electron microscope (S4800, manufactured by Hitachi, Ltd.) at a magnification of 1,000 to 20,000, and the crack width was measured. The crack width was the widest part of the observed crack.

<Observation of projecting length of carbon nanotube from crack surface in electron emission source>
Observation with a scanning electron microscope (S4800, manufactured by Hitachi, Ltd.) at a magnification of 1,000 to 20,000 times, the length of carbon nanotubes protruding from the crack surface was randomly measured at 20 points, and the average The protrusion length was calculated.

<Measurement of electric field strength>
In a vacuum chamber with a vacuum degree of 5.0 × 10 ⁻⁴ Pa, a phosphor layer having a thickness of 5 μm is formed on a substrate on which an electron emission source is formed and a soda lime glass substrate on which an ITO thin film is formed (P22, Chemical Opt). The substrate on which the Nix Corporation was formed was opposed with a spacer of 100 μm in between, and a voltage was applied at 10 V / second by a voltage applying device (withstand voltage / insulation resistance tester TOS9201 manufactured by Kikusui Electronics Co., Ltd.). . The electric field strength at which the current density reached a predetermined current value was determined from the obtained current-voltage curve (maximum current value 10 mA / cm ² ). The predetermined current value is a value described in each example and comparative example.

<Observation of light emission uniformity>
In a vacuum chamber with a degree of vacuum of 5.0 × 10 ⁻⁴ Pa, a back substrate having a 1 cm × 1 cm square electron-emitting device formed on an ITO substrate, and a phosphor layer (P22) having a thickness of 5 μm on the ITO substrate. The front substrate on which the substrate is formed is opposed with a spacer of 100 μm, and a voltage having a predetermined current value is applied by a voltage application device (withstand voltage / insulation resistance tester TOS9201 manufactured by Kikusui Electronics Co., Ltd.) The front substrate was made to emit light. The predetermined current value is a value described in each example and comparative example. The light emission area was digitized by taking a light emission image with a CCD camera and measuring the proportion of light emission in a 1 cm × 1 cm square electron-emitting device. At this time, the light emission area of 80% or more is best (A), 50% or more and less than 80% is good (B), 30% or more and less than 50% is acceptable (C), and less than 30% Was not allowed (D).

<Adjustment of particle size of residual compound>
The particle diameter of the metal salt used in the electron emission source paste of the present invention was adjusted by the following method. After weighing 20 g of metal salt and 80 g of solvent in a 500 ml zirconia container, 0.3 mmφ zirconia beads (Torayserum (trade name) manufactured by Toray Industries, Inc.) are added thereto, and a planetary ball mill (Fritsch Japan Co., Ltd.) is added. It was pulverized with a planetary ball mill P-5). The pulverized solution from which zirconia beads were removed was dried to obtain a metal salt having an average particle diameter of 1 to 3 μm.

Example 1
Double-walled carbon nanotubes were pulverized by a ball mill using zirconia balls having a diameter of 3 mm, and an organic binder, solvent, glass powder, conductive particles, residual compound, and pyrolytic foaming agent were added at a composition ratio shown in Table 1. The mixture was kneaded with three rollers to prepare an electron emission source paste.

Next, a cathode electrode was formed by depositing ITO on a glass substrate by sputtering. A 1 cm × 1 cm square coating film was printed on the cathode electrode by a screen printing method using a SUS200 mesh screen plate, and then dried at 100 ° C. for 5 minutes in a hot air dryer. The obtained paste film for electron emission source was baked at 450 ° C. in the atmosphere to obtain an electron emission source. The resulting electron emission source had a crack width of 10.5 μm and a carbon nanotube protrusion length of 2.9 μm. The electric field intensity reaching 1 mA / cm ² was 3.5 V / μm, and the light emission area at that time was 82%.

Examples 2 to 16
As in Example 1, electron emission source pastes and electron emission sources having the composition ratios shown in Tables 1 and 2 were produced. Tables 1 and 2 show the measurement results of the crack width, the protruding length of the carbon nanotube, the electric field intensity reaching 1 mA / cm ² , and the emission area. Examples 2 to 10 were obtained by changing the type of the residual compound, Examples 11 and 12 were obtained by changing the type of the pyrolytic foaming agent, and Examples 13 and 14 were obtained by changing the content of the residual compound. Examples 15 and 16 use a plurality of residual compounds. In both cases, cracks on the surface of the electron emission source and carbon nanotubes having a protrusion length of 0.5 μm or more from the crack surface were observed, and electron emission could be observed without an activation step. In addition, although the favorable result was obtained irrespective of the kind of (B) thermal decomposition type foaming agent particle and (C) component, the result when using a metal salt as a residual compound which is (C) component is more It was good and the results were particularly good when using metal carbonates.

Comparative Example 1
Double-walled carbon nanotubes are pulverized by a ball mill using zirconia balls having a diameter of 3 mm, and an organic binder, a solvent, glass powder, conductive particles, and a pyrolytic foaming agent are added at a composition ratio shown in Table 3 to form a three-roller. And kneaded to prepare an electron emission source paste.

Next, a cathode electrode was formed by depositing ITO on a glass substrate by sputtering. A 1 cm × 1 cm square coating film was printed on the cathode electrode by a screen printing method using a SUS200 mesh screen plate, and then dried at 100 ° C. for 5 minutes in a hot air dryer. The obtained paste film for electron emission source was baked at 450 ° C. in the atmosphere to obtain an electron emission source. Cracks in the obtained electron emission source and protrusions of carbon nanotubes were not observed. The electric field intensity reaching 1 mA / cm ² exceeded 15 V / μm, and the light emission area at that time was 3%.

Comparative Examples 2-5
Similarly to Comparative Example 1, an electron emission source paste and an electron emission source having the composition ratio shown in Table 3 were produced. Table 3 shows the measurement results of the crack width, the protruding length of the carbon nanotube, the electric field strength reaching 1 mA / cm ² , and the light emitting area. In Comparative Examples 2 to 4, only the residual compound was used without adding the pyrolytic foaming agent, and the width of the crack was small and the protruding length of the carbon nanotube was short. The electric field strength reaching 1 mA / cm ² was high, and the uniformity of light emission was not very good. In Comparative Example 5, polystyrene particles were added, and voids in which holes were continuously connected were formed in the electron emission source. Therefore, the crack width of Comparative Example 5 is a measurement of the width of the gap. Although the width of the apparent crack was large, the protruding length of the carbon nanotube was short. The electric field strength reaching 1 mA / cm ² was high, and the uniformity of light emission was not very good.

Example 17
The electron emission source paste was prepared as follows. After weighing 1 g of multi-walled carbon nanotubes, 8 g of glass powder, 6 g of conductive particles, 20 g of binder, and 65 g of solvent in a zirconia container having a capacity of 500 ml, 0.3 mmφ zirconia beads (Traceram (trade name) manufactured by Toray Industries, Inc.) In addition, it was predispersed at 100 rpm with a planetary ball mill (planet type ball mill P-5 manufactured by Fritsch Japan KK). The mixture from which the zirconia beads were removed was kneaded with three rollers. Next, the thermal decomposition type foaming agent 1, the thermal polymerization initiator 1 and the ethylenically unsaturated group-containing compound 1 are added so that the composition ratio shown in Table 4 is obtained, and the mixture is further kneaded with three rollers, and an electron emission source is obtained. A paste was used. These were adjusted to 6 wt% in the electron emission source paste. Next, the produced electron emission source paste was printed on a soda lime glass substrate on which an ITO thin film was formed using a SUS325 mesh screen so as to form a 5 mm × 5 mm square pattern. After drying at 100 ° C. for 10 minutes, an electron emission source was obtained by firing at 450 ° C. in the air. Cracks and carbon nanotubes having a protrusion length of 0.5 μm or more from the crack surface were observed on the surface of the obtained electron emission source, and electron emission could be observed without an activation step. The electric field intensity reaching 0.1 mA / cm ² was 8.6 V / μm, and the light emission uniformity at that time was the best (A).

Examples 18-23
In the same manner as in Example 17, an electron emission source paste and an electron emission source having the composition ratios shown in Table 4 were prepared and evaluated. In Examples 18 to 19, (B) a thermally decomposable foaming agent, (C) component thermal polymerization initiator and ethylenically unsaturated group-containing compound were used. In Examples 20 to 22, (B) a thermally decomposable foaming agent and (C) component ethylenically unsaturated group-containing thermal polymerization initiator were used. In Example 23, the thermal decomposition initiator / ethylenically unsaturated group-containing thermal polymerization initiator as component (D) was used. The total content of these in the electron emission source paste was 6 wt%. In both cases, cracks on the surface of the electron emission source and carbon nanotubes having a protrusion length of 0.5 μm or more from the crack surface were observed, and electron emission could be observed without an activation step. Table 4 shows the evaluation results of the electric field strength and the uniformity of issuance.

Examples 24-38
In the same manner as in Example 17, an electron emission source paste and an electron emission source having the composition ratios shown in Tables 5 to 7 were prepared and evaluated. In Examples 24 to 28, (B) a thermal decomposition type foaming agent, (C) component thermal polymerization initiator, ethylenically unsaturated group-containing compound and residual compound were used. In Examples 29 to 33, (B) a thermally decomposable foaming agent and (C) component ethylenically unsaturated group-containing thermal polymerization initiator and residual compound were used. In Examples 34 to 38, the residual compound as component (C) and the thermal decomposable foaming agent and ethylenically unsaturated group-containing thermal polymerization initiator as component (D) were used. Among these, the components other than the residual compounds were combined so that the content in the electron emission source paste was 6 wt%. Further, the residual compound was added so that the content in the paste was 9 wt%. In both cases, cracks on the surface of the electron emission source and carbon nanotubes having a protrusion length of 0.5 μm or more from the crack surface were observed, and electron emission could be observed without an activation step. The evaluation results of the electric field intensity and the light emission uniformity are as shown in Tables 5 to 7.

Comparative Example 6
The electron emission source paste was prepared as follows. After weighing 1 g of multi-walled carbon nanotubes, 8 g of glass powder, 6 g of conductive particles, 20 g of binder, and 65 g of solvent in a zirconia container having a capacity of 500 ml, 0.3 mmφ zirconia beads (Traceram (trade name) manufactured by Toray Industries, Inc.) In addition, it was predispersed at 100 rpm with a planetary ball mill (planet type ball mill P-5 manufactured by Fritsch Japan KK). The mixture from which the zirconia beads were removed was kneaded with three rollers. Next, the pyrolytic foaming agent 1 was added so that the content in the paste for electron emission source was 6 wt%, and further kneaded by three rollers to obtain an electron emission source paste. Next, the produced electron emission source paste was printed on a soda lime glass substrate on which an ITO thin film was formed using a SUS325 mesh screen so as to form a 5 mm × 5 mm square pattern. After drying at 100 ° C. for 10 minutes, an electron emission source was obtained by firing at 450 ° C. in the air. On the surface of the obtained electron emission source, only carbon nanotubes in which the protruding length of the carbon nanotubes protruding from the wall surface of the void was less than 0.1 μm were observed. The electric field strength reaching 0.1 mA / cm ² was 12.5 V / μm.

Comparative Examples 7-10
In the same manner as in Comparative Example 6, an electron emission source paste and an electron emission source having the composition ratios shown in Table 8 were prepared and evaluated. In Comparative Examples 7 to 10, neither (B) a pyrolytic foaming agent nor (D) a thermal polymerization initiator having an ethylenically unsaturated group functioning as a pyrolytic foaming agent was used.

In Comparative Examples 9 and 10, only a carbon nanotube with a protruding length of less than 0.1 μm of the carbon nanotube protruding from the wall surface of the void formed by firing was observed, and although electron emission was obtained, 0.1 mA / cm ² The electric field strength to reach In Comparative Examples 7 and 8, no electron emission was obtained even when an electric field strength of 16 V / μm was applied.

Examples 39-49
Similarly to Example 1, electron emission source pastes and electron emission sources having the composition ratios shown in Tables 9 to 10 were produced. Tables 9 to 10 show the measurement results of the crack width, the protruding length of the carbon nanotube, the electric field intensity reaching 1 mA / cm ² , and the light emitting area. Examples 39 to 43 were obtained by changing the content of the (B) pyrolytic foaming agent and the residual compound (C), and Examples 44 to 45 were obtained by changing the type of the component (C). Examples 46 to 49 are obtained by changing the average particle size of (B) pyrolytic foaming agent particles. In both cases, cracks on the surface of the electron emission source and carbon nanotubes having a protrusion length of 0.5 μm or more from the crack surface were observed, and electron emission could be observed without an activation step. In addition, although the favorable result was obtained irrespective of the average particle diameter of (B) thermal decomposition type foaming agent particle | grains, the result when it is 6.0 micrometers or more and 20 micrometers or less was more favorable.

Example 50
The electron emission source paste used in Example 42 was printed on a soda-lime glass substrate on which an ITO thin film was formed, using a SUS325 mesh screen plate to print a fine pattern of 200 μm × 1000 μm. After drying at 100 ° C. for 10 minutes, an electron emission source was obtained by firing at 450 ° C. in the air. FIG. 6 shows a photograph of the obtained electron emission source observed by SEM at a magnification of 500 times from a direction substantially perpendicular to the substrate. The ratio of cracks in the electron emission source corresponding to 200 μm × 200 μm was calculated from the photograph using MATLAB, and found to be 12.6%. The electric field strength reaching 1 mA / cm ² was 1.7 V / μm, and good electron emission characteristics could be obtained even in a fine pattern.

1 Crack generated in electron emission source 2 Protruding carbon nanotube 3 Crack width 4 Electron emission source 5 Cathode substrate 6 Crack 7 Protruding carbon nanotube

Claims (20)

A paste for an electron emission source comprising (A) an electron emission material, (B) a thermally decomposable foaming agent, and (C) a component that generates shrinkage stress upon thermal decomposition. The electron emission source paste according to claim 1, wherein the component (C) is a compound that thermally decomposes at 100 ° C. or more and 500 ° C. or less. The electron emission source according to claim 1 or 2, wherein the component (C) includes at least one substance selected from the group consisting of metal salts, organometallic compounds, metal complexes, silane coupling agents, and titanium coupling agents. For paste. The electron emission source paste according to claim 1 or 2, wherein the component (C) includes a thermal polymerization initiator and an ethylenically unsaturated group-containing compound. The electron emission source paste according to claim 1 or 2, wherein the component (C) includes a thermal polymerization initiator containing an ethylenically unsaturated group. A paste for an electron emission source, comprising: (A) an electron emission material; and (D) a thermal polymerization initiator that functions as a thermal decomposition type foaming agent and has an ethylenically unsaturated group. The paste for an electron emission source according to any one of claims 1 to 6, for producing an electron emission source having a crack. The electron emission source paste according to any one of claims 1 to 7, further comprising an inorganic powder. The paste for an electron emission source according to any one of claims 1 to 5, 7 or 8, wherein the thermal decomposition temperature of the (B) thermal decomposition type foaming agent is 50 to 300 ° C. 10. The electron emission source paste according to claim 1, wherein the (B) pyrolytic foaming agent has an average particle size of 1.0 to 25 μm. The (B) pyrolytic foaming agent is one or more substances selected from the group consisting of azo compounds, nitroso compounds, hydrazide compounds, azide compounds, hydrazone compounds, melamine, urea and diciamine amide. 7. The electron emission source paste according to any one of 7 to 10. The paste for an electron emission source according to claim 6, wherein the thermal decomposition temperature of the thermal polymerization initiator (D) which functions as a thermal decomposition type foaming agent and contains an ethylenically unsaturated group is 50 to 300 ° C. 7. The electron emission source paste according to claim 6, wherein (D) the thermal polymerization initiator that functions as a pyrolytic foaming agent and contains an ethylenically unsaturated group has an average particle size of 1.0 to 25 μm. . (D) The thermal polymerization initiator that functions as a pyrolytic foaming agent and contains an ethylenically unsaturated group is selected from the group consisting of an azo compound, a nitroso compound, a hydrazide compound, an azide compound, and a hydrazone compound 1 or The paste for an electron emission source according to claim 6, wherein the paste is two or more substances. The paste for an electron emission source according to any one of claims 4 to 14, further comprising at least one substance selected from the group consisting of metal salts, organometallic compounds, metal complexes, silane coupling agents, and titanium coupling agents. . The paste for an electron emission source according to claim 3 or 15, wherein the metal salt contains a metal carbonate. The paste for an electron emission source according to claim 3, 15 or 16, wherein the metal salt contains magnesium. An electron emission source produced by heat-treating the electron emission source paste according to any one of claims 1 to 17, wherein the electron emission source has a crack and the electron emission material projects from the crack surface. 18. An electron-emitting device manufactured by heat-treating the electron-emitting source paste according to claim 1, comprising an electron-emitting source having a crack and having an electron-emitting material protruding from the crack surface. Electron emission device. A method for producing an electron emission source, wherein the electron emission source paste according to any one of claims 1 to 17 is heat-treated to have a crack and an electron emission material projects from the crack surface.

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