JP2823420B2 - Liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device (hereinafter, referred to as a liquid crystal display device).
More specifically, the present invention relates to a filler material mixed in a sealant.

[0002]

2. Description of the Related Art In an LCD, a first electrode substrate on which a first transparent electrode is patterned and a second electrode substrate on which a second transparent electrode is patterned are used to regulate a sealant and a cell gap. And the first and second transparent electrodes are electrically connected to each other via a transfer agent, and the liquid crystal is placed in a space defined by the two electrode substrates and a seal pattern. Injecting.

[0003] Conventionally, the base of the sealant has been
Although thermosetting resins such as epoxy resins are often used,
In recent years, as described in, for example, JP-A-62-231927 and JP-A-3-157615, a technique using an ultraviolet-curable resin as the sealant, or a technique disclosed in, for example, JP-A-1-266510 As described in Japanese Patent Application Laid-Open Publication No. H11-11223, a technique using a mixed resin of an ultraviolet-curable resin and a thermosetting resin as the sealant, for example, Japanese Patent Application Laid-Open No. 55-100529, and the like. As described in Japanese Patent Application Laid-Open No. H10-157, a technique using a filler added to an ultraviolet curable resin as the sealant has been proposed. When a filler is added to the resin base, the stress acting on the seal pattern can be reduced, and the adhesive strength of the seal pattern can be increased.

[0004]

Heretofore, scaly fillers having high effects as described above have been awarded. However, if this kind of filler is added to the resin base, after forming the seal pattern, when the electrode substrate is bonded and pressed, a large number of fillers are likely to overlap each other, so that a desired cell gap cannot be obtained. Or 2 fillers
Inconveniences such as agglomeration and disorder of the seal pattern are likely to occur.

An object of the present invention is to solve the above-mentioned deficiencies of the prior art, and an object of the present invention is to provide an LCD having a high cell gap accuracy and a small seal pattern disturbance.

[0006]

According to the present invention, there is provided a sealant comprising a base resin based on a mixed resin of an ultraviolet curable resin and a thermosetting resin, and a filler mixed therein. In the liquid crystal display element in which the seal pattern was formed, a silane-treated spherical filler was used as the filler. As the spherical filler, those having a diameter in the range of 0.5 to 1.1 μm are particularly suitable. A specific material name of the filler includes spherical silica. Further, an insulating carbon may be mixed into the resin base together with the filler.

[0007]

When a spherical filler is used, a large number of fillers are unlikely to overlap when an electrode substrate is bonded and pressed after forming a seal pattern. Therefore, the cell gap accuracy is not affected by the filler, and a high-accuracy cell gap accuracy can be obtained. In addition, when the silane-treated spherical filler is used, the dispersibility in the resin base is improved, so that secondary aggregation is less likely to occur and a seal pattern with less disturbance can be formed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the structure of an LCD according to the present invention will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 1 is a plan view of an LCD according to the present invention, FIG. 2 is a developed view of the LCD according to the present invention, and FIG. 3 is a sectional view of a main part of the LCD according to the present invention.

In these figures, 1 is a first electrode substrate, 2 is a first transparent electrode patterned on one surface of the electrode substrate 1, 3 is a second electrode substrate, and 4 is a single electrode on one surface of the electrode substrate 3. Patterned second transparent electrodes, 5 indicates a seal pattern, 6 indicates a transfer pattern, 7 liquid crystal, and 8 indicates a sealing stopper. As is apparent from these figures, in the LCD of this example, the transparent electrode forming surfaces of the two electrode substrates 1 and 3 are bonded together via the seal pattern 5 and formed on the respective electrode substrates 1 and 3. The transparent electrodes 2 and 4 are connected via a transfer pattern 6. A space defined by the two electrode substrates 1 and 3 and the seal pattern 5 is filled with a liquid crystal 7, and an inlet of the liquid crystal 7 is sealed with a sealing plug 8.

[0010] In general, an LCD is, as shown in FIG.
A first master glass 9 having a size corresponding to a plurality of first electrode substrates 1 and having a plurality of sets of first transparent electrodes 2 and a seal pattern 5 formed on one side; and a second electrode substrate 3 A second master glass 1 having a size corresponding to a plurality of second transparent electrodes 4 and a plurality of sets of second transparent electrodes 4 and transfer patterns 6 formed on one surface.
In this method, a master having a plurality of empty cell containers is manufactured by bonding these, and the empty cell containers are cut and separated to obtain individual empty cell containers. Alignment marks 11 and 12 are formed on the first and second master glasses 9 and 10 at opposite positions in a diagonal direction for positioning the two master glasses. In FIG. 9, a temporary fixing pattern 13 for temporarily fixing both master glass is formed in the other diagonal direction. Alignment mark 1
In order to enhance the positioning accuracy, it is preferable that the reference numerals 1 and 12 be provided as close as possible to the periphery of the master glasses 8 and 9.
In order to increase the positioning accuracy, the temporary fixing pattern 13 is preferably located near the periphery of the master glasses 8 and 9 as much as possible.
Further, it is preferable to provide them at positions separated from the alignment marks 11 and 12. The temporary fixing pattern 13
Are formed thicker than the seal pattern 5 and the transfer pattern 6, and the transfer pattern 6 is formed thicker than the seal pattern 5. As a result, the respective parts are securely bonded.

As the sealant and the temporary fixing pattern agent, a mixed resin of an ultraviolet curable resin and a thermosetting resin is used. Specifically, the ratio of the modified acrylate oligomer and the epoxy oligomer is (90:10) to (40:60), more preferably (70:30) to (50:50).
Can be used. When using this composition, the heating temperature in the heating step is set to 11
The temperature can be set to about 0 ° C to 120 ° C.
1 which is the optimum heating temperature when using a sealing agent of 00%
The heating temperature can be lowered by 40 ° C. to 60 ° C. as compared with 60 ° C. to 180 ° C. Therefore, the alignment accuracy at the time of bonding the electrode substrates is improved, and the warpage due to the temperature difference between the two electrode substrates is reduced. Further, the change in the pretilt angle of the STN, which is easily affected by the temperature, is reduced, and the display unevenness is reduced.

[0012] A reactive diluent is added to the mixed resin in an amount of 1 to 30% by weight, more preferably 2 to 10% by weight, based on 100 parts by weight of the oligomer, and an epoxy curing agent is added to 100 parts by weight of the oligomer. 2 to 30% by weight, more preferably 5 to 25% by weight, and the photopolymerization initiator is oligomer 1
0.1 to 10% by weight, more preferably 0.5 to 4% by weight, is added to 00 parts by weight. The photopolymerization initiator has a wavelength of 360 nm to 430 n within the range of the addition amount.
Those that absorb ultraviolet rays of m (the peak of the spectrum of a metal halide lamp) with high efficiency are preferred. Specific examples of this type of photopolymerization initiator include a thioxanthone-based photopolymerization initiator represented by the chemical structural formula of FIG. 5 and an acylphosphine oxide-based photopolymerization initiator represented by the chemical structural formula of FIG. is there.

In order to improve the adhesive strength and reduce the adhesive stress, a filler may be added to the mixed resin. The filler is preferably a spherical filler having a diameter of about 0.5 μm to 1.1 μm in order to prevent secondary aggregation and prevent disturbance of the seal pattern 5 and the temporary fixing pattern 13. Spherical silica of diameter is preferred. Silane treatment of the filler
0.5 to 3.0% by weight of a silane coupling agent is dissolved in a volatile solution such as alcohol, and a filler is added to the solution and left for about 1 hour. Then, about 10
The solution can be heated to 0 ° C., the solution can be blown off, and the surface of the filler can be coated (bonded) with a silane coupling agent. It is appropriate that the amount of the filler added to the resin is up to about 35%.

Further, in order to alleviate the thermal stress of the seal pattern 5 and prevent the seal pattern 5 from cracking, a reactive elastic material such as a butadiene-modified epoxy resin may be added to the mixed resin. Also, after product assembly,
In order to prevent light leakage from the seal pattern portion of the LCD panel, an insulating carbon powder may be added to the mixed resin. The particle size of the carbon powder is 1.5 μm
Hereinafter, the thickness is more preferably 0.5 to 1.0 μm, and the addition amount of the carbon powder to the mixed resin is 0.1 to 2.9.
% By weight, more preferably about 0.1 to 0.5% by weight. In order to obtain good printability, the sealing agent and the temporary fixing pattern agent have a TI value of 1.2 to 1.5 and a viscosity of 20.
It is adjusted to about 000 to 50,000 cps.

FIG. 7 shows a more preferable composition example of the sealing agent and the temporary fixing pattern agent.

Hereinafter, an example of a method of manufacturing the LCD will be described with reference to FIGS. FIG.
FIG. 4 is a manufacturing process explanatory diagram showing a flow of an LCD manufacturing process.

In step S1, a plurality of sets of first transparent electrodes 2 are pattern-formed on the first master glass 8 on which the alignment marks 10 are displayed (see FIG. 4).

At the same time, in step S2,
A plurality of sets of second transparent electrodes 4 are pattern-formed on the second master glass 9 on which the alignment marks 11 are displayed (see FIG. 4).

In step S 3, a plurality of sets of seal patterns 5 and temporary fixing patterns 13 are formed on the first master glass 8.
And screen print.

At the same time, in step S4,
The transfer pattern 6 is patterned on the second transparent electrode 4 patterned on the second master glass 9.

The formation of the transparent electrodes 2 and 4, the seal pattern 5, the temporary fixing pattern 13 and the transfer pattern 6 in each of the above steps is performed with reference to the alignment marks 10 and 11 displayed on the master disks 8 and 9, respectively. Will be In addition, the seal pattern 5 and the temporary fixing pattern 1
3. The printing apparatus for the transfer pattern 6 will be described later in detail with reference to FIGS.

In step S5, the seal pattern 5 and the temporary fixing pattern 13 formed on the first original glass 8 and the transfer pattern 6 formed on the second original glass 9 are irradiated with infrared rays. Remove air bubbles. Since the ultraviolet curable resin contains an acrylic-modified monomer, bubbles are easily entrained during printing, and a defoaming treatment is indispensable. When infrared rays are used as a heat source, the defoaming treatment can be completed in a short time because the resin is easily absorbed by the resin. For example, in heating in a furnace, a defoaming process that required 40 ° C. × 5 minutes can be completed in 30 seconds by using infrared rays.

In step S6, a spacer material having a diameter corresponding to a desired cell gap is sprayed on one master glass 9. The spacer material can be sprayed by spraying a mixed solution of Freon and isopropyl alcohol to which a spacer material has been added with nitrogen gas.

In step S7, the original glasses 8, 9 are aligned with the alignment marks 10, 11 displayed on the respective original glasses 8, 9 with the transparent electrodes 2, 4 formed on the inner side. Perform positioning (alignment). At this time, by selectively pressing only the temporary fixing pattern 13 forming portion of the master glass 8 or 9, the alignment can be adjusted without affecting the seal pattern 5 and the transfer pattern 6.

In step S8, the temporary fixing pattern 1
3 is irradiated with resin curing light, and the temporary fixing pattern 13 is irradiated.
Is hardened to temporarily fix the master glasses 8 and 9.

In step S9, foreign matter such as glass powder adhered to the press device for adjusting the cell gap, particularly the pressurized portion thereof is removed. This is because a local force acts on the master glasses 8 and 9 during pressurization to prevent the master glasses 8 and 9 from breaking. Removal of foreign matter can be performed using an adhesive roller or the like. This operation can be performed by monitoring the presence or absence of a foreign object with a CCD camera or the like and executing the operation only when there is a foreign object. In addition, the static elimination blow is attached to the press device, or conductive particles are applied to the diaphragm portion of the press device to prevent the device from being charged, and as a result, foreign matter such as glass powder is not attached to the press device. Can also.

In step S10, the temporarily fixed master glasses 8, 9 are mounted on a press. The press device incorporates a resin curing light irradiation device. Then, the temporarily fixed master disks 8 and 9 are pressed in the contact direction to adjust the cell gap, and then irradiated with resin curing light on the same stage to cure the ultraviolet curing resin contained in the seal pattern 5 and the transfer pattern 6. To cure. The pressing force applied to the master glass 8, 9 during pressing is 0.1k
Gently pressurize from g / cm ² to about 1.0 kg / cm ² over 30 to 60 seconds. By doing so, the line width of the seal pattern 5 becomes uniform, liquid crystal leakage and the like are prevented, and the reliability of the LCD is improved. In particular, it is effective for a micro LCD such as a camera LCD in which the area occupied by the seal pattern 5 is relatively large with respect to the LCD area. FIG. 9 shows a seal pattern when pressed by the above-described pressing method and a seal pattern when pressed at a higher speed. FIG. 9A shows a product of the present invention,
FIG. 9B shows a conventional product. However, both samples had a sealant film thickness of 20 μm and a spacer diameter of 5.8 μm, and were subjected to heat leveling at 80 ° C. for 3 minutes after printing.

As a light source of the resin curing light, a high-pressure mercury lamp,
In addition to a mercury discharge lamp such as an ultra-high pressure mercury lamp and a metal halide lamp, an electrodeless lamp can be used. Electrodeless lamps have a higher UV output efficiency than mercury discharge lamps (about 36.5%; mercury discharge lamps
%), Because the output efficiency of infrared rays is low,
9 has the advantages of being able to suppress the temperature rise, has a long service life, does not require an electrical connection, is easily attached to and removed from a press device, and can be quickly started up. More preferred.

In step S11, the master disks 8, 9 whose cell gap has been adjusted are transferred to a cell gap measuring device, and the cell gap is measured. Then, step S1
In 2, it is determined whether the cell gap is within the design value. If it is determined in step S12 that the cell gap is within the design value, the process proceeds to step S13. If it is determined in step S12 that the cell gap is out of the designed value, the process goes to step S14, and a warning is issued to stop the line. This makes it possible to quickly take measures against the inconvenience, as compared with the case where the cell gap is measured after filling the liquid crystal, and to reduce the inconvenience rate.

In step S13, the master glass 8,
9 is applied to a pressure-heating device to cure the thermosetting resin contained in the seal pattern 5 and the transfer pattern 6. At this time, it is preferable that interleaving paper provided with conductivity is interposed between the pressurized portion of the pressurizing / heating device and the master glasses 8, 9 to prevent the master glasses 8, 9 from being charged. In this way, it is possible to prevent the liquid crystal from being abnormally deflected due to the charging, that is, the inconvenience that an abnormal horizontal or vertical line is displayed on the LCD product.

Finally, in step S15, the individual empty cell containers are divided according to a standard method, the liquid crystal 7 is filled in the empty cell containers, and the liquid crystal injection port is sealed, and the LCD shown in FIG. obtain.

FIGS. 10 to 13 show an example of a printing apparatus used for forming a pattern such as the seal pattern 5.
As is apparent from FIGS. 10 to 12, the printing apparatus of the present embodiment includes a plate frame 21, a screen net 22 stretched over the plate frame 21, and a squeegee 24 for applying the mixed resin 23.
It is composed of The plate frame 21 and the screen net 22 are formed of a conductive material. And
As shown in detail in FIG. 11, the plate frame 21 and the screen net 22 are electrically connected via a conductive tape 25, and the plate frame 21 is grounded via a ground wire 26. As described above, the use of the antistatic printing apparatus prevents the charging of the mixed resin 23 and reduces the possibility of stringing of the mixed resin, thereby reducing printing errors. FIG. 12 shows the effect of the grounding mechanism when various materials are used for the screen net 22. As is apparent from this figure, if a screen net 22 made of metal (stainless steel) or a metal mask is used and a grounding mechanism is provided, the electrostatic amount of the screen net 22 can be reduced to 100 volts, and the screen net 22 can be charged. It can be understood that the inconvenience caused by the above can be completely prevented.

As described above, the temporary fixing pattern 1
3 is formed thicker than the seal pattern 5 and the transfer pattern 6, and the transfer pattern 6 is formed thicker than the seal pattern 5. As described above, when patterns having different thicknesses are printed on the same master glass, as shown in FIG. 13, the thickness of the perforated resist film 27 formed on the screen net 22 is reduced to a small value. This can be dealt with by making the portion where the pattern is formed thinner and making the portion where the thicker pattern is formed thicker. Specifically, the resist film 2 in the seal pattern forming portion
By setting the thickness d _{1 of} 7 to 6 to ₁₀ μm, the seal pattern 5 of that thickness can be formed, and the thickness d ₂ of the resist film 27 in the temporary fixing pattern forming portion is set to ₂ to 5 μm.
By increasing the thickness by μm, the temporary fixing pattern 13 having the thickness can be formed. As described above, when the seal pattern 5 and the temporary fixing pattern 13 having different thicknesses are formed by one screen printing, the temporary fixing pattern is formed on the master glass using, for example, a dispenser after forming the seal pattern. As compared with the case where the means is used, the manufacturing efficiency is remarkably improved. In addition, when the temporary fixing pattern 13 is formed by screen printing, the uniformity of the application amount can be remarkably improved as compared with the case where a dispenser is used, so that the application amount is too large and a desired cell gap accuracy cannot be obtained. Also, there is no inconvenience that a desired temporary fixing strength cannot be obtained due to an insufficient amount of coating.

[0034]

As described above, according to the present invention,
Since the silane-treated spherical filler is mixed and added into the resin base, the cell gap accuracy is not affected by the filler, and a high-accuracy cell gap accuracy can be obtained. Also, since the dispersibility in the resin base becomes good,
Secondary aggregation is less likely to occur and a seal pattern with less disturbance can be formed.

[Brief description of the drawings]

FIG. 1 is a plan view of an LCD according to an embodiment.

FIG. 2 is a development view of the LCD according to the embodiment.

FIG. 3 is an exploded sectional view of a main part of the LCD according to the embodiment.

FIG. 4 is a development view of a master glass according to the example.

FIG. 5 is an explanatory diagram showing a chemical structural formula of a thioxanthone-based photopolymerization initiator.

FIG. 6 is an explanatory diagram showing a chemical structural formula of an acylphosphine oxide-based photopolymerization initiator.

FIG. 7 is an explanatory view showing a composition example of a preferable sealing agent and a temporary fixing pattern agent.

FIG. 8 is a flowchart showing a manufacturing process of the LCD.

FIG. 9 is an explanatory diagram of a seal pattern.

FIG. 10 is a sectional view of a printing apparatus.

FIG. 11 is a sectional view of a main part of the printing apparatus.

FIG. 12 is an explanatory diagram illustrating an effect of the printing apparatus according to the embodiment.

FIG. 13 is a cross-sectional view of a principal part showing an example of a resist film formed in a printing apparatus.

[Explanation of symbols]

 1,3 Electrode substrate 2,4 Transparent electrode 5 Seal pattern 6 Transfer pattern 7 Liquid crystal 8 Sealing plug 9,10 Master glass 11,12 Alignment mark 13 Temporary fixing pattern

Continued on the front page (72) Inventor Hisao Kimura 1-7 Yukitani-Otsukacho, Ota-ku, Tokyo Alps Electric Co., Ltd. (72) Inventor Tsutomu 1-7 Yukitani-Otsukacho, Ota-ku, Tokyo Alps Electric Co., Ltd. In-company (56) References JP-A 2-1820 (JP, A) JP-A 1-173013 (JP, A) JP-A 61-138232 (JP, A) JP-A 62-295029 (JP, A) JP-A-2-114233 (JP, A) JP-A-3-63629 (JP, A) JP-A-55-100529 (JP, A) JP-A-58-105124 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) G02F 1/1339 505

Claims (4)

(57) [Claims] 1. A liquid crystal display element in which a seal pattern is formed by using a sealant obtained by mixing a filler with a base resin based on a mixed resin of an ultraviolet-curable resin and a thermosetting resin, A liquid crystal display device using a silane-treated spherical filler. 2. The liquid crystal display device according to claim 1, wherein the diameter of the filler is in a range of 0.5 to 1.1 μm. 3. The liquid crystal display device according to claim 1, wherein said filler is spherical silica. 4. The liquid crystal display device according to claim 1, wherein insulating carbon is mixed in the base together with the filler.