JP4246758B2 - Manufacturing method of FPD - Google Patents

Description

The present invention relates to a method of manufacturing a FPD using a sealant consisting of hot melt type adhesive.

  A flat panel display (referred to as FPD in this specification) is a term that is contrasted with a display device having a bulge, such as a cathode ray tube of a CRT display, has a small depth, saves space, and has no bulge in the display panel. There is a big feature in the point, and a liquid crystal display, a plasma display, an organic EL display etc. are 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 hydrofluoric acid and chemically polished to reduce the thickness (see FIGS. 3A and 3B).

  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).
Japanese Patent Application No. 2005-349714

  However, the sealing material SE of the UV curable resin is not only expensive, but once cured, there is a problem that even if a sealing failure portion is discovered thereafter, the portion cannot be repaired. For this reason, a laminated glass substrate having even a poorly sealed portion can no longer be made thinner, and all of the plurality of display panels PN... PN may be wasted.

  On the other hand, in order to avoid such a problem of defective sealing, the amount of momentum applied tends to increase. In this sense, the use of the UV curable resin greatly increases the manufacturing cost. In addition, the excessively applied resin remains as a sharp edge after the glass substrate is thinned (see FIG. 3D), and the processing is extremely complicated.

From the above situation, it is strongly desired that when a defective sealing portion is detected, it can be repaired and the manufacturing cost can be reduced. The present invention is based on the above requirements, and an object of the present invention is to provide a method for manufacturing an FPD that is inexpensive to manufacture and that can easily correct a defective sealing portion.

  As a result of intensive studies, the present inventors have found that a thermoplastic adhesive exhibiting a specific softening point has a sufficient sealing effect to prevent infiltration of a chemical polishing liquid, and further, as a sealing material, a glass substrate The present invention has been completed by finding that it can be used in a condition that does not damage the display element disposed therebetween.

That is, the first invention, a sealing material made of hot melt type adhesive is heated to 60 ° C. or higher, a first step of its viscosity to melt so that the 300~800mPa · s, 2 glass substrates A second step in which the sealing material melted in the first step is provided in a band shape in the gap formed on the peripheral side surface of the laminated glass substrate having a display element disposed therebetween, and then the solidified sealing A third step of reheating so as to melt the material again , and after the third step, the outer surface of the bonded glass substrate whose peripheral side surface is sealed by the cooled and solidified sealing material is hydrofluoric acid. polishing the outer surface of the glass substrate is contacted with the chemical polishing solution containing a fourth step and method of manufacturing a flat panel display manufactured Nde including a thinning of the glass laminate substrate to a predetermined thickness. Here, the hot melt type is, for example, a hot melt type adhesive (hot melt type) among adhesives classified into a room temperature curing type, a heat curing type, a pressure sensitive type, a rewet type, and a thermal melting type (heat sensitive type). Adhesive). 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 adhesive of the present invention is a thermoplastic adhesive, which melts by heating and solidifies and adheres by cooling. Since the adhesive of the present invention is thermoplastic, it can be melted again by reheating after solidification, and a defective sealing portion can be repaired. Therefore, the minimum required amount of sealing material is sufficient, and not only the manufacturing cost is reduced, but also the occurrence of an edge after chemical polishing can be prevented.

  The softening point of the sealing material of the present invention is preferably 60 ° C. or higher and lower than 100 ° C., more preferably 65 ° C. or higher and lower than 90 ° C., and most preferably 65 ° C. or higher and lower than 85 ° C. 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 measurement 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, if 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 hot melt adhesive used as the sealing material of the present invention include those containing a paraffinic material 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.

2nd invention is the mounting process which mounts on the peripheral side surface of the bonding glass substrate formed by arrange | positioning a display element between two glass substrates, without softening the sealing material which consists of a hot melt type adhesive agent. And, with respect to the sealing material placed in the previous placing step, after the heating step, the heating step of dissolving the heat so that the viscosity is 300 to 800 mPa · s and entering the gap on the peripheral side surface , The outer surface of the bonded glass substrate whose peripheral side surface is sealed by the cooled and solidified sealing material is brought into contact with a chemical polishing liquid containing hydrofluoric acid to polish the outer surface of the glass substrate, and the bonding a polishing step for thinning the glass substrate to a predetermined thickness, a comprise manufacturing method of a flat panel display that is producing.

In any of the inventions, the sealing material for manufacturing the FPD is provided in a band shape in the gap generated at the peripheral edge of the laminated glass substrate (two glass substrates). The side where the sealing material is provided does not include the outer surfaces of the front and back surfaces of the laminated glass substrate. The width of the sealing material is preferably narrow, but on the other hand, if it is too narrow, it becomes difficult to obtain a sufficient sealing effect, so an appropriate width is determined by the balance between the two.

In the first aspect of the invention, the sealing material is melted by heating, illustrates a method of dip the glass laminate substrate by a predetermined depth (immersion), Ru is penetrating the sealing material which is melted in the gap between the glass substrate can do. When the dip method is adopted, it is preferable to mask the outer surfaces of the front and back surfaces except for the side surfaces of the laminated glass substrate, and to provide the sealing material only on the side surfaces of the laminated glass substrate.

As a method of the first invention , it is also preferable to apply a molten sealing material to the upper peripheral side surface of the upright laminated glass substrate. In this case, it is preferable that the molten sealing material is slowly discharged toward the gap on the peripheral side surface during the coating operation. Moreover, the process of reheating a sealing material is provided after the application | coating process of a sealing material. In this case, the same process is repeated on the four sides of the laminated glass substrate, but the coating process and the reheating process may be continued for each side, and after finishing the coating process on the four sides, each process is repeated. You may perform a reheating process with respect to 4 sides.

In the second invention, for example, a sealing material formed in a narrow band shape or a thread shape having a predetermined thickness (the cross section is round or square) is placed on the peripheral side surface of the laminated glass substrate , and heated and dissolved. After entering the gap between the glass substrates, it is solidified.

  Even when any of the above-described methods is employed, an excision step of scraping off the sealing material present on the peripheral side surface of the bonded glass substrate may be provided prior to the polishing step. In this case, no matter how thin the glass substrate is by chemical polishing, the remaining sealing material does not form an edge. However, even without such a cutting step, an extra sealing material is left on the peripheral side surface of the laminated glass substrate by using a thin strip-shaped sealing material or by providing a reheating step as necessary. It is possible not to.

  After sealing the periphery of the laminated glass substrate with a sealing material in this way, the outer surface of the glass substrate is brought into contact with a chemical polishing liquid to polish the outer surface of the glass substrate, and the glass substrate is made to a predetermined thickness. make it thin. Examples of the method of bringing into contact with the chemical polishing liquid include a method of immersing the glass substrate in the chemical polishing liquid or applying the chemical polishing liquid to the outer surface of the glass substrate.

  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.

  Thus, after polishing the outer surface of each glass substrate to make the laminated glass substrate have a predetermined thickness, the FPD is obtained by washing with washing water.

  When the gap between the glass substrates constituting the FPD is sealed using the FPD manufacturing sealing material of the present invention, the sealing effect is sufficiently prevented to prevent the chemical polishing liquid from entering, as in the case of the conventional UV curable resin. Have. Moreover, this sealing material can be used on the conditions which do not damage the display element clamped by the bonding glass substrate. Furthermore, this sealing material can be obtained from an inexpensive material, and since it is made of a thermoplastic adhesive, it can be easily corrected by reheating even if a sealing failure occurs. .

  Next, the best mode for carrying out the present invention will be described with reference to examples. However, the examples do not limit the scope of the present invention, and are not limited to the scope of the present invention. What was changed into this form is also included in the scope of the present invention.

1. Bonding of glass substrates Two glass substrates (size: 50 mm × 50 mm, thickness: 0.7 mm) were bonded using a tape glue so that a gap of about 10 μm was generated between the glass substrates ( Hereinafter referred to as a bonded substrate).
2. Sealing operation The masking tape is cut to a width of about 1 cm, and as shown in FIG. 1, the edges of the masking tape are attached to both surfaces of one side of the outer peripheral portion of the bonded substrate so that the edges of the masking tape are aligned. (Both sides are protruded by about 1 cm. Note that the protruding tapes are bonded to each other, but for convenience of drawing, they are described as non-bonded in FIG. 1.)
The following sealing material is heated and melted on a hot plate so as to have the melt viscosity shown in Table 1, and the side where the masking tape is stuck in the sealing material is shown in Table 1 (time). Dip with Then, after cooling to room temperature by air cooling and solidifying a sealing material, the part which protruded about 1 cm at a time on both sides is cut, and also the masking tape stuck on the board | substrate is peeled off.

The above operation was similarly performed for the remaining three sides, and the four sides of the bonded substrate were sealed to obtain a sealed glass substrate. Then, the presence or absence of the sealing defect location was observed visually. The results are shown in Table 1.
[Encapsulant]
1) Sealing material A
Softening point 80 ℃
2) Sealing material B
Softening point 65 ° C

  The temperature was measured using an alcohol thermometer and an infrared radiation thermometer.

As is apparent from the results shown in Table 1, when the sealing material A was used, the periphery of the glass substrate could be sealed without any problems under the conditions of a melt viscosity of 650 mPa · s and a dip time of about 9 seconds. . Further, when the sealing material B was used, the periphery of the glass substrate could be sealed without any problems under the conditions of a melt viscosity of 350 mPa · s and a dip time of about 6 seconds.
3. Polishing Step The above-described sealed and peeled glass substrate (total thickness of glass: 0.7 mm × 2 = 1.4 mm) is set on a carrier and polished until the total thickness becomes 0.3 mm under the following conditions. did. Thereafter, the state of the sealing material and the presence or absence of liquid intrusion were visually confirmed. Table 2 shows the results and the time required for polishing (polishing time).

Under the polishing conditions of the experiment, the plate thickness was polished from 1.4 mm to 0.3 mm over 2 hours and 53 minutes. However, when either the sealing material A or the sealing material B was used, the change was visually observed. There was no liquid intrusion.
4). Comparative Experiment of Adhesive Strength of Sealing Material In order to compare the adhesive strength between the UV curable resin and the sealing material of the present invention, the following experimental conditions and procedures were performed. The results are shown in Table 3.
1) Experimental conditions Glass substrate: 50 × 50 × 0.7 mmt
Sealing material: (1) Sealing material A
(2) UV curable resin (conventional product)
Measuring instrument: push-pull scale
2) Experimental procedure [Measurement of adhesive strength of sealing material A]
a. 0.05 g of the sealing material A is placed on a glass substrate and melted on a hot plate.
b. As shown in FIG. 2, a clip having a bottom area of about 0.9 cm ² is placed on the melted sealing material.
c. After returning to room temperature, it is allowed to stand for about 5 minutes to completely cure the sealing material.
d. Connect a push-pull scale to the clip hook.
e. A glass substrate is fixed, it pulls up manually, and the measured value when a sealing material peels is confirmed. The same operation was repeated and the average was obtained.
[Measurement of adhesive strength of UV curable resin]
a. 0.05 g of UV curable resin is placed on a glass substrate, and a clip having a bottom area of about 0.9 cm ² is placed on the melted sealing material as shown in FIG.
b. UV irradiation is performed for about 15 minutes to completely cure the encapsulant.
c. Connect a push-pull scale to the clip hook.
d. A glass substrate is fixed, it pulls up manually, and the measured value when a sealing material peels is confirmed. The same operation was repeated 5 times and the average was obtained.

  The adhesive strength when using the sealing material A, which is the hot melt adhesive of the present invention, is almost equivalent to the adhesive strength when using the UV curable resin, which is a conventional sealing material, and is about 70 N. It was. Although the sealing material B was inferior to the sealing material A, almost satisfactory results were obtained.

  For the sealing material A, the dip temperature is changed to change the melt viscosity to about 500 to 800 mPa · s. For the sealing material B, the dip temperature is changed to about 300 to 500 mPa · s. The same experiment was carried out by changing, but the results were not inferior to the above in all performances.

It is a plane explanatory view showing one process (attachment of a masking tape) of sealing work. It is a perspective view for demonstrating the comparative experiment of adhesive force. It is drawing explaining a bonding glass substrate.

Claims (4)

A first step of heating a sealing material composed of a heat-dissolving adhesive to 60 ° C. or higher and melting it so that its viscosity is 300 to 800 mPa · s ;
A second step in which the sealing material melted in the first step is provided in a band shape in the gap formed on the peripheral side surface of the laminated glass substrate in which the display element is disposed between the two glass substrates;
Thereafter, a third step of reheating so as to melt the solidified sealing material again ,
After the third step, the outer surface of the bonded glass substrate whose peripheral side surface is sealed by the cooled and solidified sealing material is brought into contact with a chemical polishing liquid containing hydrofluoric acid, thereby the outer surface of the glass substrate. And a fourth step of thinning the laminated glass substrate to a predetermined thickness;
Method of manufacturing a flat panel display manufactured Nde including a. In the second step , the laminated glass substrate is immersed in the melted sealing material , and the sealing material is infiltrated into the gap, or an upper peripheral side surface of the laminated glass substrate that is upright. The manufacturing method according to claim 1, wherein a process of discharging and applying the sealing material is performed.   The manufacturing method according to claim 1, wherein the sealing material has a melt viscosity at a melting temperature of 180 ° C. of 650 mPa · s or less and a melt viscosity at a melting temperature of 80 ° C. of 300 mPa · s or more. A placing step of placing a sealing material made of a heat-melting adhesive on the peripheral side surface of a laminated glass substrate in which a display element is disposed between two glass substrates without softening;
About the sealing material placed in the previous placing step, a heating step in which the viscosity is 300 to 800 mPa · s and is dissolved by heating so as to enter the gap on the peripheral side surface ;
After the heating step, the outer surface of the bonded glass substrate whose peripheral side surface is sealed by the cooled and solidified sealing material is brought into contact with a chemical polishing liquid containing hydrofluoric acid to thereby change the outer surface of the glass substrate. A polishing step for polishing and thinning the laminated glass substrate to a predetermined thickness;
Method of manufacturing a flat panel display that is comprise produce.

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