JP2008116648A - Manufacturing method of flat panel display and sealing material used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an improved manufacturing method of an FPD (Flat Panel Display) so that a necessary quantity of sealing material can be automatically applied in a narrow gap. <P>SOLUTION: The manufacturing method includes a step for automatically applying the sealing material by ejecting the heat melting type colored sealing material having hydrofluoric acid resistance and ≥60°C softening point to a peripheral edge ED of a lamination glass GL wherein a display element is disposed between two glass substrates from an ejecting nozzle part 3 of a dispenser horizontally moved along the peripheral edge ED of the glass substrate GL by a front rotational roller 1 and a rear rotational roller 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sealing material for sealing a peripheral edge between two glass substrates, and a method for manufacturing an FPD using the sealing material.

  Flat panel display (referred to herein as FPD) is a term that is contrasted with a display device having a bulge, such as a cathode ray tube of a CRT display. It has a great feature in that it is small in depth and space-saving and the display panel does not bulge, and liquid crystal displays, plasma displays, organic EL displays and the like have been put into practical use. Among FPDs, in particular, liquid crystal displays are widely used not only as television receivers but also as display devices for mobile phones and computer equipment.

  By the way, based on the demand for lighter and thinner liquid crystal displays, recently, a method of chemically polishing a laminated glass substrate constituting a liquid crystal display to the limit is suitably employed. Specifically, the first and second glass substrates 60 and 60 provided with a plurality of display panel regions PN... PN are bonded, and the periphery of the bonded glass substrate GL is tightly sealed. It is immersed in an aqueous solution containing hydrogen fluoride HF and chemically polished to reduce the thickness (see FIGS. 2A and 2B).

  According to this chemical polishing method, not only a plurality of display panels PN... PN can be manufactured together, but also the processing speed is faster than that of mechanical polishing, so that there is an advantage that the productivity is excellent. Further, since the laminated glass substrate GL can be thinned to the limit, it is possible to meet further demands for thinning and lightening the display panel PN.

In the above manufacturing method, the hydrofluoric acid-resistant sealing material SE that seals the periphery of the laminated glass substrate GL is required. Conventionally, a UV curable resin has been used as the sealing material SE (patents). Reference 1).
However, this UV curable resin sealing material SE is not only expensive, but also requires an ultraviolet irradiation step after the coating operation, resulting in poor work efficiency.

Here, in order to improve work efficiency, (a) to develop a sealing material that does not require ultraviolet irradiation, (b) to penetrate into the gap between the laminated glass substrates with a minimum required coating amount. Therefore, it is desired that the sealing performance is exhibited and (c) the inspection after application is easy. In consideration of such problems, the applicant has previously proposed a heat-melting type sealing material (Patent Document 2), but the gap between the laminated glass substrates GL is only about 5 μm. It is necessary to further improve the properties of the sealing material and the coating method.
The present invention has been made based on such an idea, and an FPD manufacturing method improved so that a necessary amount of a sealing material can be reliably applied to a narrow gap, and used in this method. An object is to provide a sealing material.

  In order to achieve the above object, the present inventor arranges a display element between two glass substrates with a hydrofluoric acid-resistant sealing material colored with a heat melting type having a softening point of 60 ° C. or higher. The manufacturing method of the flat panel display which has the process of apply | coating automatically to the periphery of the laminated glass substrate formed in this way was completed.

  Here, an adhesive is typically used as the heat-melting type sealing material, and is classified into, for example, a room temperature curing type, a heat curing type, a pressure-sensitive type, a re-humidity type, and a heat melting type (heat-sensitive type). Of the adhesives, a hot-melt adhesive is preferably used. In addition, an adhesive agent is not understood in a narrow sense, but contains all what has the adhesiveness which exhibits a predetermined sealing effect.

  In any case, the sealing material of the present invention is a thermoplastic adhesive, which melts by heating and solidifies and adheres by cooling. And since the sealing material of this invention is colored, even if it applies mechanically, it is easy to detect a defective location by a subsequent test | inspection.

  And the sealing material can be re-applied to the defective part, and furthermore, since this sealing material is thermoplastic, it can be melted again by reheating after solidification, and the defective sealing part can be repaired. It can be carried out. Therefore, the necessary minimum amount of sealing material is sufficient, and the manufacturing cost is reduced.

  As the colorant, a material that can be seen even with a thickness of about 5 μm is selected corresponding to the gap between the laminated glass substrates GL. Although pigments such as green, red, and black can be used as the colorant, according to the inventors' investigation, white pigments are effective from the viewpoint of visibility. It is particularly preferable to mainly use a white pigment and add a green or red pigment thereto. A white color in which green and red are mixed at a ratio of 1 to white 5 to 3 is the most effective for visual recognition.

  As the white pigment, zinc white (zinc oxide), lithopone, titanium dioxide, lead white (lead carbonate) and the like are suitable. In particular, use of titanium dioxide is preferable. Here, the blending amount with respect to the heat-melting type adhesive is selected to be the minimum amount at which the coated portion can be visually observed even when the adhesive is applied to the gap of the glass substrate having a thickness of 5 μm.

  As described above, the adhesive of the present invention contains pigments and the like, and the softening point thereof is preferably 60 ° C. or higher and lower than 100 ° C., more preferably 65 ° C. or higher and lower than 90 ° C., optimally 65 ° C. or higher and 85 ° C. It is less than ℃. When the softening point is less than 60 ° C., a sufficient sealing effect may not be exhibited in the chemical polishing step. If the softening point is too high, the workability of the sealing process is impaired. Here, the softening point is a value measured by the ring-and-ball method under the conditions described in JAI (Japan Adhesive Industry Association Standard) -7. Preferably, it is measured using an automatic softening point measuring machine.

  The adhesive of the present invention preferably has a melt viscosity at a melting temperature of 180 ° C. of 650 mPa · s or less (more preferably 400 mPa · s or less), and a melt viscosity at a melting temperature of 80 ° C. of 300 mPa · s or more (more preferably). 400 mP · s or more). The measuring method is according to JAI-7, and the melt viscosity is measured using a Brook Field type automatic viscometer (spindle No. 27, rotation speed 10 rpm). The sealing material of the present invention is bonded to the periphery of the glass substrate in a molten state, but when the melt viscosity at a melting temperature of 180 ° C. exceeds 650 mPa · s, when heated to obtain a desired melt viscosity In addition, the internal display element may be damaged. On the other hand, when the melt viscosity at a melting temperature of 80 ° C. is less than 300 mPa · s, there is a possibility that the necessary sealing performance cannot be exhibited in a processing temperature range such as a chemical polishing step.

  The sealing material of the present invention has a melt viscosity of 200 to 1000 mPa · s, preferably 300 to 800 mPa · s, more preferably, from the viewpoint of workability of the sealing process and the permeability of the sealing material. It is performed in the range of 350 to 650 mPa · s. If the viscosity is too low, the sealing material penetrates deeply into the glass substrate, and the periphery of the glass substrate cannot be optimally sealed.

  Preferred examples of the adhesive used as the sealing material of the present invention include those containing a paraffinic substance such as paraffin wax or a synthetic resin such as a thermoplastic resin.

  Examples of paraffinic substances used here include vacuum wax distillation oil, vacuum distillation residue oil, petroleum wax and natural wax separated and refined from heavy distillate oil, and blended products containing these resins, especially thermoplastic resins, etc. Etc. Examples of the thermoplastic resin include synthetic resins such as ethylene / vinyl acetate copolymer, petroleum resins, and modified products thereof.

  Examples of the chemical polishing liquid include hydrofluoric acid water containing hydrofluoric acid as an essential etching component, preferably 1 to 45% by weight, more preferably 1 to 35% by weight, and still more preferably 1 to 25%. Used in a concentration range of weight percent. If the concentration of hydrofluoric acid exceeds 45% by weight, the etching rate becomes too fast, resulting in a problem that the flatness of the etched glass portion is deteriorated. On the other hand, when the hydrofluoric acid concentration is less than 1% by weight, the etching rate becomes too slow and the time required for etching becomes long.

  In addition to hydrofluoric acid, it may contain at least one inorganic acid selected from hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid. In addition to hydrofluoric acid, carboxylic acid, phenolic, amide, fatty acid ester, and phosphoric acid ester are added in addition to hydrofluoric acid from the viewpoint of preventing reaction products such as silicofluoride generated by etching from adhering to the glass substrate. It may contain at least one surfactant selected from a system, a sulfate ester system, a sulfonic acid system, an amine system, an ether system, and a polymer alcohol. Although it does not specifically limit as a grinding | polishing speed | rate, Usually, it carries out at about 0.5-10 micrometers / min.

  When sealing the gap between the laminated glass substrates constituting the FPD using the heat melting type sealing material of the present invention, the same as in the case of the conventional UV curable resin, regardless of the colorant contained It has a sufficient sealing effect to prevent the chemical polishing liquid from entering. Moreover, this sealing material can be used on the conditions which do not damage the display element clamped by the bonding glass substrate. Furthermore, since the sealing material is appropriately colored, it is easy to detect a portion where the coating penetration amount is insufficient, and the sealing material has thermoplasticity. For example, the sealing material is reused and heated. Just make it easier to fix it.

  Hereinafter, the present invention will be described in more detail based on examples. The manufacturing method which concerns on an Example is comprised by the application process of a sealing material, the reheating process of a sealing material, and the test process of an application state. FIG. 1A is a drawing for explaining the coating process.

<Sealing material application process>
In the sealing material application process, an automatic application device (dispenser) in which the front rotation roller 1, the rear rotation roller 2, and the discharge nozzle portion 3 are integrated is used. Specifically, the automatic coating apparatus horizontally moves in the direction of the arrow on the upper part of the laminated glass substrate GL held in the vertical state, and the sealing material is automatically applied to the upper peripheral edge ED of the glass substrate GL in the process of horizontal movement. To be applied.

  Each of the two rotating rollers 1 and 2 is configured such that a rotating body 4 having a substantially U-shaped notch is rotatably held on a rotating shaft 5. Both ends of the rotating shaft 4 are held by the connecting arm 6. The rotating rollers 1 and 2 are not placed on the peripheral edge ED of the laminated glass substrate and rolling, but gently hold the peripheral edge ED of the laminated glass substrate GL to the discharge nozzle portion 3. In contrast, it is used for positioning a laminated glass substrate.

  The discharge nozzle portion 3 is a portion that discharges the melted sealing material, and communicates with a tank portion (not shown) that holds the sealing material in a heated state. The discharge nozzle portion 3 is configured by connecting a cylindrical main body portion 30 and a conical tip portion 31, and a fluorine sponge rubber and a silicon rubber sheet are wound around the outer periphery of the cylindrical main body portion 30 in this order. This is to suppress the amount of heat released from the discharge nozzle portion 3 and to discharge the sealing material with a predetermined viscosity.

  The sealing material of the example is configured by adding titanium dioxide as a white pigment to a heat-melting type adhesive having a softening point of 65 ° C. or higher and lower than 90 ° C. (optimally 65 ° C. or higher and lower than 85 ° C.). . And in the Example applied in the periphery ED of the bonding glass substrate GL, in the Example, the sealing material is discharged in the heating state used as the viscosity of about 350-650 mPa * s. Here, the lower the viscosity is, the better the permeability into the gaps in the glass substrate is, so that the subsequent reheating step for the sealing material can be omitted. However, if it is in the said viscosity range, even if a viscosity is relatively high, the permeability | transmittance of a sealing material can be ensured in a subsequent reheating process.

<Reheating process>
Next, a plurality of glass substrates GL. In the reheating step, only the peripheral edges of the four sides of the laminated glass substrate are selectively heated. Therefore, there is no adverse effect on the electronic elements and the like inside the laminated glass substrate.

  Moreover, the softening point of the sealing material of the present invention is 65 ° C. or higher and lower than 90 ° C. (optimally 65 ° C. or higher and lower than 85 ° C.), and the reheating process can be completed quickly. Work efficiency is better than the conventional manufacturing method which requires ultraviolet irradiation time. Note that the reheating operation is not performed on the peripheral edges of the four sides at the same time, but is performed for each side located in the upper part, but the operation time is shorter than when the UV curable resin is used.

<Inspection process>
In the inspection process, the penetration state of the sealing material is visually confirmed. The sealing material applied in the dissolved state is naturally cooled and solidified in the process of penetrating into the gaps between the glass substrates. And the tip into which the sealing material has penetrated usually forms a gentle wavy line.

  In the inspection process, the wavy tip line is visually confirmed. If a location where the coating amount is insufficient is detected, repair work is performed with a manual dispenser. This inspection work may be performed prior to the reheating step.

  The first embodiment of the present invention has been described above, but the specific contents do not particularly limit the present invention. For example, in the embodiment of FIG. 1A, the two rotating rollers 1 and 2 are used, but a single rotating roller may be used. In this case, preferably, only the front rotating roller 1 is configured. Further, as long as the laminated glass substrate GL can be correctly positioned with respect to the discharge nozzle unit 3, it is not always necessary to use a rotating roller. For example, a planar holding body having a U-shaped cut is used. You may make it drive | work ahead of the discharge nozzle part 3. FIG.

  Moreover, it is not always necessary to run the holding part of the laminated glass substrate corresponding to the discharge nozzle part. FIG.1 (b) illustrates the structure which hold | maintains a bonding glass substrate with the holding plate 10 comprised by the cross-section "C" shape. The holding plate 10 is configured to be movable up and down, and after the laminated glass substrate GL is received at the position of the coating apparatus, the holding plate 10 descends and gently holds the laminated glass substrate. Then, after that, the sealing nozzle is applied while the discharge nozzle portion 3 travels in the horizontal direction on the upper surface of the holding plate 10.

  By the way, this holding plate 10 has a built-in heater. Therefore, the applied sealing material is maintained in a reheated state for a predetermined time, and the sealing material is completely infiltrated. Therefore, according to the embodiment of FIG. 1B, the coating operation and the reheating operation can be continued for each sheet.

It is drawing explaining a sealing process. It is drawing explaining the manufacturing method of FPD.

Claims (8)

A sealing material that has hydrofluoric acid resistance and is colored with a heat-melting type having a softening point of 60 ° C. or higher is automatically applied to the periphery of a laminated glass substrate in which a display element is arranged between two glass substrates. The manufacturing method of the flat panel display which has a process. The sealing material includes a paraffinic material or a thermoplastic resin, and has a melt viscosity of 650 mPa · s or less at a melting temperature of 180 ° C. and a melt viscosity of 300 mPa · s or more at a melting temperature of 80 ° C. Item 2. The manufacturing method according to Item 1. The manufacturing method according to claim 1, wherein the sealing material is a colored adhesive containing a white pigment. The said sealing material is a manufacturing method in any one of Claims 1-3 discharged toward the said periphery from a nozzle in a melted state. The manufacturing method according to any one of claims 1 to 4, wherein the nozzle discharges the sealing material while moving corresponding to a moving body that moves while holding a peripheral edge of the bonded glass substrate. The manufacturing method according to claim 5, wherein the bonded glass substrate in which the sealing material is applied to the peripheral edge is transferred to a process in which the peripheral edge is reheated together with another bonded glass substrate. The manufacturing method according to any one of claims 1 to 4, wherein the sealing material is applied to a peripheral edge of the bonded glass substrate while being held by a plate material incorporating a heater. A sealing material that is a heat-melting colored adhesive having a softening point of 60 ° C. or higher, and seals the periphery of a laminated glass substrate for a flat panel display with hydrofluoric acid resistance.

Images