MXPA97007876A - A composition of photoconductor layer for an exhibition panel to co - Google Patents

Abstract

A styrene-acrylic copolymer is used as an organic binder, a thioxanxeno derivative is used as an electron receptor and a tetraphenylbutadiene derivative is used with an electron donor to produce a color display panel, which has a low decomposition temperature, a high electron transfer capacity and a load holding capacity to manufacture a color display panel without a change in brightness and color coordinates on a fluorescent screen

Description

A COMPOSITION OF PHOTOCONDUCTOR LAYER FOR A COLOR EXHIBIT PANEL DESCRIPTION OF THE INVENTION The present invention relates to a photoconductive layer for a color display panel, more specifically, a composition of a photoconductive layer for a color display panel, which comprises a styrene-acrylic copolymer as an organic binder, a thioxanxone derivative as an electron receptor and a tetraphenylbutadiene derivative as an electron donor. This composition has a low decomposition temperature, a high electron transfer capacity and load holding capacity to produce a color display panel without changing the brightness and color coordinates on a fluorescent screen. A fluorescent layer for a color display panel is manufactured using a rotating method of a suspension coating method. At first, a panel of a glass lamp is rotated, a photoprotective layer such as polyvinyl alcohol and ammonium chloride is coated thereon and the panel is heated and dried. The panel is assembled with a mask assembly to produce a panel mask assembly and the photoresist on it is exposed to ultraviolet (uv) rays through a slot of mask in the shape of a point or a strip to stick on the panel. The assembly is washed with deionized water to remove the photoresist, which was not exposed to uv rays, and dried. A space between the dots (or strips) is coated with a non-fluorescent photoabsorbent such as a graphite solution, dried by heating and washed with hydrogen peroxide. The panel is washed through a high pressure spray of distilled water to remove photoresist and graphite. The panel is dried by spinning rapidly to form a black matrix. Fluorescent materials of red, green and blue are applied between the black matrices to produce a fluorescent layer. There are two methods to apply fluorescent materials to the black matrix, mainly a suspension method and an electrophotographic method. The suspension method is carried out as follows. A suspension of red fluorescent material is coated on a panel by rapidly rotating the panel at a constant speed. The panel is heated to dry the fluorescent materials and exposed to light using a mask. After exposure, the mask is removed and the fluorescent material, which has not been exposed to light, is removed using deionized water to produce spots or strips of red fluorescent material. The same process, mentioned in the above, is used to produce points or strips of green and blue fluorescent material. He The final panel is composed of thousands of points or strips. The exposure to light is identical with the previous process, except that the fluorescent material is exposed to light, using a light source with a special angle and over the fixed point so as not to overlap three fluorescent materials. Finally, the fluorescent layer is dried to form a fluorescent screen. The difference in diameter of the central point and the peripheral point in the fluorescent layer produced by this method is severe and the shape of the dots is distorted to make an interior color purity. The electrophotographic screen process in which the disadvantage of the previous suspension method is eliminated, is described as follows. A conductive material is coated on the inner surface of a faceplate panel of a color display panel to form a conductive layer and a photoconductive material is overcoated in the conductive layer to form a photoconductive layer. Then, a substantially uniform voltage is applied to the photoconductive layer of the panel and selected areas of the photoconductive layer are exposed to visible light to affect the charge thereon, without affecting the charge on the unexposed area of the photoconductive layer. The fluorescent layer is formed by the spraying of a powder of material fluorescent on the exposed area of the photoconductive layer. While the photoconductive layer plays the role of an insulator in the dark, an electrolyte emits electrons or holes in the UV light source or visible rays. The structure of a fluorescent layer for a color display panel comprising a photoconductive layer is described in FIGURES 3 and 4. The photoconductive layer comprises an organic conductive layer (13) and a charge originator / charge carrier layer ( 15) coated on a dispersed polymer charge originator and a charge carrier on a color display panel (11) in FIGURE 3. Holes or electron carriers such as hydrazone, styryl, pyrazorin compounds can be added to the polymer. , triphenylamine. In addition, the photoconductive layer is formed to coat an electron donor (25) on an organic conductive layer (13) and to laminate an electron receptor (27) thereon. The electron donor (25) and the electron receptor (27) are dispersed in a binder polymer. Electron bearers or holes such as hydrazone, styryl, pyrazorin, triphenylamine compounds can be added to the polymer as a charge transport support. A photoconductive layer composition consists of an organic binder, an electron receptor, a electron donor and a residual solvent. The general organic binders used are polyvinylcarbazole, polymethyl methacrylate or polypropylene carbonate. The electron receptors used are hydrazone, styryl, pyrazorine and triphenyla ine compounds, which have low conductivity and low molecular weight, and are used for copying machines. The corona charging process (-) has to be carried out due to these compounds that transport holes, which produce a large amount of ozone. As a method to solve this problem, Japanese Patent Laid-Open No. 2-214866, Sho 61-233750 discloses trinitrofluorenone (TNF), anthraquinone derivative as electron receptors and dimethylphenyldiphenylbutatriene (DMPBT) as electron donors. Previous electron donors and donors do not carry and maintain sufficient electron charges and for use with the polymer binder. The imperfect combustion of the photoconductive material coated on the panel occurs in the process to seal a panel / funnel at a temperature of 450 ° C, because dimethylphenyldiphenylbutatriene decomposes at high temperatures. Consequently, more than 10% of the photoconductive materials remain thus reducing the fluorescent brightness and the color coordinate for a color display panel.

Accordingly, the present invention seeks to overcome the above described disadvantages of the conventional art and provide a composition of a photoconductive layer for a color display panel, which has a low decomposition temperature, a high electron transfer capacity and a load maintenance capability to produce a color display panel without changing the brightness and color coordinates on a fluorescent screen. One embodiment of the present invention provides a photoconductive layer composition for a color display panel comprising styrene-acrylic copolymer as an organic binder expressed as the following formula 1, a thioxanxene derivative as an electron acceptor expressed as the formula 2 below, a tetraphenylbutadiene derivative as an electron donor expressed as the following formula 3 and solvent, [formula 1] [formula 2] [formula 3] wherein, R-, and R 2 are independently hydrogen or an alkyl group, R 3 is an alkyl group or an alkylene group and X is a polar group, and 1, m and n can change to control the concentration of the photoconductive material and the surface charge, R4 is one of the carbonyl groups substituted with an alkyl group, an alkoxy group or an aryl group, R5 is selected from the group consisting of hydrogen, halogen, an alkyl group, an alkoxy group, a cyano group, a nitro group, an ester group and a trifluoromethyl group, and Rg is a dimethylamine group or a methoxy group and R7 is hydrogen, a methoxy or dimethylamine group. The preferred composition comprises from 4-21% by weight of the styrene-acrylic copolymer as an organic binder. When used below 4% by weight of the organic binder in the present invention, the surface voltage is not sufficient and the thickness of the layer is thin. In addition, when the organic binder is used above 21% by weight in the present invention, the thickness of the layer is thicker than necessary. The preferred composition comprises 0.2-2.2% by weight of thioxanxen derivative as an electron donor. When used below 0.2% by weight or above 2.2% by weight of the electron donor, in the invention, the surface voltage drops below 150 V and the voltage ratio of the surface according to the time is reduced. The preferred composition comprises from 0.8-5.8% by weight of tetraphenylbutadiene derivative. When the electron donor is used below 5.8% by weight or above 4.98% by weight, in the invention, the surface voltage ratio according to time falls below 0.7 V. The preferred solvent is selected of the group consisting of toluene, alcohol and acetone.

The preferred R 4 in formula 2 is selected from the group consisting of ethoxycarbonyl, butoxycarbonyl, phenoxycarbonyl, benzyloxycarbonyl, ethylcarbonyl, propylcarbonyl, butylcarbonyl and t-butylcarbonyl. One embodiment of the present invention provides a thioxanxeno derivative as an electron acceptor for the photoconductive layer of a color display panel expressed in formula 2. The preferred R4 in formula 2 is selected from the group consisting of ethoxycarbonyl, butoxycarbonyl , phenoxycarbonyl, benzyloxycarbonyl, ethylcarbonyl, propylcarbonyl, butylcarbonyl and t-butylcarbonyl. The electron donor and the electron receptor are produced as a complex body to have a good electron production capacity. Insulating materials with an adhesion property and used as electrophotographic fluorescent materials are used as the polymer. For example, polystyrene, polymethacrylate, alphamethylstyrene and copolymers thereof are used. The coating of an organic conductive layer and the electron transport material are made using rotation coating, wire coating and roller coating, etc. The thickness of an electron that produces a layer and a transport layer is below 5 microns as shown in FIGURE 3. In FIGURE 4, each transport layer is preferred to be below 3 microns. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described in greater detail, with reference to the accompanying drawings, in which: FIGURE 1 is a graph illustrating the property of thermal decomposition according to the temperature of a photoconductive composition for a panel of conventional color display. FIGURE 2 is a graph illustrating the property of thermal decomposition according to the temperature of a photoconductive composition for a display panel of the present invention. FIGURE 3 is a cross-sectional view of a photoconductive layer for a color display panel. FIGURE 4 is a cross-sectional view of a photoconductive layer for a color display panel. Although the invention has been described with reference to a preferred embodiment, it should be understood that the invention is not limited to the preferred embodiment as described herein. EXAMPLE 1 4 g (0.013 mole) of 10, 10-dioxide of 9-oxo-9H-thioxanxene-3-carboxylic acid and 4.89 g (0.036 mole) of 1-bromobutane in 110 ml of dimethylformamide were dissolved.

(DMF) and a small amount of NaHCOj is added to react at 40 ° C for 4-8 hours. The reagent was added to a large amount of distilled water and an organic layer was produced by separation. The organic layer was purified by performing the column separation to obtain 4.5 g of 9-oxo-9H-thioxanxene-3-butylester. 10.5% by weight of the styrene-acrylic copolymer (SEKISUI CHEMICAL Co., S-LECP) was mixed as an organic polymer, 1.5% by weight of di-diethylaminotetraphenylbutadiene as an electron donor and 0.42% by weight of the thioxanxeno derivative of formula 2 substituted with R4 with an ethoxycarbonyl group as an electron receptor for 5 hours to produce a photoconductive material. The material was spin coated on the organic conductive layer to produce a photoconductive layer to form a 4 micron fluorescent layer. The photoconductive layer is carried out by means of corona discharge of + 40 V and exposed to the light of a 400 lux high pressure Hg lamp to examine the loading property. After charging the initial surface voltage Vn, the ratio of the surface voltage change after 1 minute V1 / VQ, the remaining voltage Vr were measured. VQ was +480 V, the dark decay rate V_ / VQ was 0.98 and Vr was below 30 V.

EXAMPLE 2 Example 1 was repeated except that diethylaminotetraphenylbutadiene was used as an electron donor. The results were similar to the results of Example 1. EXAMPLE 3 Example 1 was repeated except that dimethoxytetraphenylbutadiene was used as an electron donor. The results were similar to the results of Example 1. EXAMPLE 4 Example 1 was repeated except for the thioxanxene derivative of formula 2 substituted with R 4 with a butoxycarbonyl group as an electron receptor. The results were similar to the results of Example 1. EXAMPLE 5 Example 1 was repeated except for the thioxanxene derivative of formula 2 substituted with R4 with a t-butyl group as an electron receptor. The results were similar to the results of Example 1. EXAMPLE 6 Example 1 was repeated except for the thioxanxene derivative of formula 2 substituted with R 4 with a phenoxycarbonyl group as an electron receptor. The results were similar to the results of Example 1.

EXAMPLE 7 Example 1 was repeated except for the thioxanxene derivative of formula 2 substituted with R 4 with an octylcarbonyl group as an electron receptor. The results were similar to the results of Example 1. EXAMPLE 8 Example 1 was repeated except for the thioxanxene derivative of formula 2 substituted with R 4 with a butoxycarbonyl group and R 5 with a cyano group as an electron receptor. The results were similar to the results of Example 1. EXAMPLE 9 Example 1 was repeated except that diethylaminotetraphenylbutadiene was used as an electron donor and the fluorenone derivative of formula 2 substituted with a butoxycarbonyl group as an electron receptor. The results were similar to the results of Example 1. EXAMPLE 10 Example 1 was repeated except that diethylaminotetraphenylbutadiene was used as an electron donor and the thioxanxene derivative of formula 2 substituted with R4 with a t-butyl group as a receptor electrons The results were similar to the results of Example 1.

EXAMPLE 1 Example 1 was repeated except that diethylaminotetraphenylbutadiene was used as an electron donor and the thioxanxene derivative of formula 2 substituted with R 4 with a phenoxycarbonyl group as an electron receptor. The results were similar to the results of Example 1. EXAMPLE 12 Example 1 was repeated except that diethylaminotetraphenylbutadiene was used as an electron donor and the thioxanxene derivative of formula 2 substituted with an octoxycarbonyl group as an electron receptor. The results were similar to the results of Example 1. EXAMPLE 13 Example 1 was repeated except that diethylaminotetraphenylbutadiene was used as an electron donor and the thioxanxene derivative of formula 2 substituted with R4 with a t-butyl group and R5 with an cyano group as an electron receptor. The results were similar to the results of Example 1. EXAMPLE 14 Example 1 was repeated except that diethylaminotetraphenylbutadiene was used as an electron donor and the thioxanxene derivative of formula 2 substituted with R 4 with a butoxycarbonyl group as an electron receptor. The results were similar to the results of Example 1. EXAMPLE 15 Example 1 was repeated except that dimethoxytetraphenylbutadiene was used as an electron donor and the thioxanxene derivative of formula 2 substituted with R4 with a t-butyl group as a receptor. electrons The results were similar to the results of Example 1. EXAMPLE 16 Example 1 was repeated except that dimethoxytetraphenylbutadiene was used as an electron donor and the thioxanxene derivative of formula 2 substituted with R4 with a phenoxycarbonyl group as an electron receptor. The results were similar to the results of Example 1. EXAMPLE 17 Example 1 was repeated except that dimethoxytetraphenylbutadiene was used as an electron donor and the thioxanxene derivative of formula 2 substituted with an octoxycarbonyl group as an electron receptor. The results were similar to the results of Example 1.

EXAMPLE 18 Example 1 was repeated except that dimethoxytetraphenylbutadiene was used as an electron donor and the thioxanxene derivative of formula 2 substituted with R4 with a t-butyl group and Rc, with a cyano group as an electron receptor. The results were similar to the results of Example 1. COMPARATIVE EXAMPLE Example 1 was repeated except that 10.5% by weight of polypropylene was used as an organic binder, 0.42% by weight of trinitrofluorenone was used as an electron receptor and 1.5 was used. % by weight of dimethylphenyldiphenylbutatriene as an electron donor. The results were similar to the results of Example 1. The change in weight of the photoconductive layers produced in Example 1 to Example 18 and the Comparative Example were measured using a DT / TGA machine while increasing the temperature to 500 ° C at the speed of 10 ° C / minute. The results of these are shown in Table 1 below.

Table 1 The thermal decomposition property of the photoconductive composition of the previous examples had lower decomposition temperatures and decomposed by 99.8% compared to that of the conventional photoconductive composition. This fact is shown in FIGURES 1 and 2. The photoconductive composition for a color display panel according to the present invention has a low decomposition temperature and an excellent thermal decomposition property. Therefore, an organic material did not remain without any change of brightness of the fluorescent screen and the color coordinate. Especially, since TNF was not used because it is known to be a carcinogen and contaminant, the thioxanxone derivative and the tetraphenylbutadiene derivative in the photoconductive composition according to the present invention have no environmental problems.

Claims (6)

1. CLAIMS 1. A composition of a photoconductive layer for a color display panel characterized in that it comprises: a styrene-acrylic copolymer as an organic binder expressed as the following formula 1; a thioxanxone derivative as an electron acceptor expressed as formula 2 below; a tetraphenylbutadiene derivative as an electron donor expressed as the following formula 3; and a solvent, [formula 1] Rt Ri I I - CH2 [formula 2] [formula 3] wherein, R-1 and R 2 are independently hydrogen or an alkyl group, R 3 is an alkyl group or an alkylene group and X is a polar group, and 1, m and n can be changed to control the concentration of the photoconductive material and the surface charge, R4 is a carbonyl group substituted with an alkyl group, an alkoxy group or an aryl group, R? is selected from the group consisting of hydrogen, halogen, an alkyl group, an alkoxy group, a cyano group, a nitro group, an ester group and a trifluoromethyl group, and Rg is a dimethylamine group or a methoxy group and R7 is hydrogen, a methoxy or dimethylamine group. 2. The composition of a photoconductive layer for a color display panel according to claim 1, characterized in that the composition comprises from 4-21% by weight of the styrene-acrylic copolymer, 0.2-
2. 2.2% by weight of the derivative of thioxanxen and 0.8-5.8% by weight of the tetraphenylbutadiene derivative.
3. 3. The composition of a photoconductive layer for a color display panel according to claim 1, characterized in that the solvent is selected from the group consisting of toluene, alcohol and acetone.
4. 4. The composition of a photoconductive layer for a color display panel according to claim 1, characterized in that R4 in formula 2 is selected from the group consisting of an ethoxycarbonyl group, a butoxycarbonyl group, a phenoxycarbonyl group, a group benzyloxycarbonyl, an ethylcarbonyl group, a propylcarbonyl group, a butylcarbonyl group and a t-butylcarbonyl group.
5. 5. A thioxanxeno derivative as an electron acceptor for a photoconductive layer of a color display panel expressed in formula 2.
6. 6. The thioxanxeno derivative as an electron acceptor for a photoconductive layer of the color display panel of according to claim 5, characterized in that R4 in formula 2 is selected from the group consisting of an ethoxycarbonyl group, a butoxycarbonyl group, a phenoxycarbonyl group, a benzyloxycarbonyl group, an ethylcarbonyl group, a propylcarbonyl group, a butylcarbonyl group and a group t-butylcarbonyl.