JPH08234213A - Liquid crystal display manufacturing method - Google Patents

Abstract

(57) [Summary] [Object] To provide a manufacturing method of a liquid crystal display device having a uniform cell gap, a reduction in alignment deviation, a display quality, and a highly reliable seal. [Constitution] Substrate 1A on which glass fiber spacer material is dispersed
A sealing material 3 containing an ultraviolet curable component and a heat curable component
The substrate 1B provided with is bonded in a vacuum, the substrate is pressed by atmospheric pressure to prepare a cell, the seal portion of this cell is temporarily cured by ultraviolet rays, and the seal is finally cured by heating to prepare a liquid crystal display device. . [Effect] The stress applied to the substrate is not biased, the alignment is not displaced, a uniform cell gap is obtained, the peeling of the seal after the provisional curing of the sealing material due to ultraviolet rays does not occur, and the seal is heated and cured. A liquid crystal cell having excellent adhesiveness and moisture resistance can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display device which can be used as a display device for many electronic devices.

[0002]

2. Description of the Related Art A method of manufacturing a liquid crystal display device in which liquid crystal is sealed between two substrates which have been subjected to an alignment treatment, the two substrates are bonded together via a spacer, and then the two substrates are aligned. , To get a uniform cell gap,
A method is well known in which a pressure plate, a weight, or the vacuum packaging described in JP-A-59-232315 or JP-B-6-68669 is used to pressurize the substrate and heat-cure the sealing material. .

Further, a method has also been proposed in which the ultraviolet curable resin alone, or the ultraviolet curable resin and the heat curable resin are separately formed in parallel to form a seal portion.

Particularly, in the method of forming the seal portion in parallel with the ultraviolet-curable component and the heat-curable component, in order to solve the problem caused by the decrease in viscosity due to heating of the heat-curable sealing material as described above, the seal portion is eliminated. A method is used in which an ultraviolet curable component is applied to the inner side, that is, to the liquid crystal material side, first, ultraviolet rays are irradiated and then heat curing is performed.

[0005]

The internal heat-curing type sealing material of the above-mentioned conventional proposals has a viscosity that decreases before the sealing material is cured by heating, resulting in misalignment of the substrate. Along with the decrease, problems such as poor orientation due to swelling and spread, deterioration of linearity, or rupture of the seal occurred, resulting in a decrease in yield.

[0006] Further, in the method of forming the seal portion in parallel with the ultraviolet curable resin alone or the ultraviolet curable resin and the heat curable resin separately, it is possible to suppress the misalignment of the substrate. There is a problem in that the stress applied to the substrate is biased by the pressure plate and the weight, and the sealing material peels off at the panel corners.

In particular, the ultraviolet curing component alone has a problem that the strength of the sealing material is insufficient and the substrates are separated from each other.

Further, in the case where the ultraviolet curing component and the ultraviolet curing component and the heat curing component are used in parallel and the vacuum packaging is used as the pressing means, the substrate is pressed and fixed by the vacuum packaging, so that Although the sealing material does not peel off after curing, there is a problem in that misalignment occurs due to the shrinkage of the vacuum packaging bag during pressurization.

If a sealing material containing a thermosetting type or an ultraviolet curable type is used, so-called thermosetting such as uncured resin or unreacted thermosetting agent or photopolymerization initiator, reactive diluent or polymerization accelerator is used. Component or UV curable component,
There is also a serious problem that the characteristics are deteriorated by causing an interaction with the liquid crystal or a component having a function of aligning the liquid crystal.

In view of the above, the heat-curing type sealing material has a problem that the viscosity of the sealing material is lowered by the heat applied during curing, which causes the seal to rupture, the linearity to deteriorate, and the orientation to fail. There is.

Further, an ultraviolet curable resin and a heat curable resin are used in parallel in parallel, two substrates with electrodes are attached to each other, and then a cell is prepared by using vacuum packaging, and the sealing material is irradiated with ultraviolet rays. If a method of manufacturing a liquid crystal display device is used in which temporary curing is performed and then main curing is performed by heating, problems such as tearing of the seal and defective alignment are solved, but shrinkage of the vacuum packaging bag during vacuum packaging This causes a problem that the substrate is misaligned.

The present invention provides a uniform cell gap,
It is an object of the present invention to provide a method for manufacturing a liquid crystal display device that can eliminate misalignment between substrates and that has excellent sealability linearity, adhesiveness, and moisture resistance.

[0013]

In order to solve the above-mentioned problems, the present invention provides a liquid crystal display device having a liquid crystal between two substrates with electrodes, at least one of which is provided with an electrode at the end of the substrate. A seal portion forming step of forming a seal portion using a seal material containing an ultraviolet curing component and a heat curing component, a substrate attaching step of attaching the other of the substrates via a spacer means, and at least the seal portion. A method for manufacturing a liquid crystal display device is used which includes a temporary curing step of irradiating ultraviolet rays to temporarily cure the seal portion and a main curing step of heating after the temporary curing step and finally curing the seal portion that has been temporarily cured. are doing.

Further, it is preferable that the manufacturing method includes a dropping step of dropping liquid crystal between the sealing portion forming step and the laminating step.

[0015]

According to the method of manufacturing a liquid crystal display device according to the present invention, after two electrodes-attached substrates are laminated to form a cell,
By using a sealing material containing a UV-curable component and a heat-curable component, and irradiating ultraviolet rays to the cell's sealing part to perform temporary curing, the viscosity of the sealing material can be reduced like the conventional heat-curable sealing material. The influence on the orientation due to the accompanying sagging spread,
Problems such as disconnection of seals are solved.

Further, since the present invention uses the sealing material containing the ultraviolet curing component and the heat curing component, the temporary curing is carried out by the ultraviolet curing component, and the viscosity of the seal portion is improved to eliminate the misalignment of alignment and the like, and the heat curing is performed. By the main curing by the components, the adhesive strength as the sealing material can be maintained.

Further, according to the present invention, since the sealing material integrally including the ultraviolet curing component and the heat curing component is used, it is possible to separately form the ultraviolet curing component and the heat curing component as in the conventional manufacturing method. Since it does not exist, the process can be simplified.

Further, according to the preferred manufacturing method of the present invention including the dropping step of dropping the liquid crystal between the seal portion forming step and the presence step, it is possible to prevent the interaction between the seal material before curing and the liquid crystal. Therefore, a display device having stable characteristics can be manufactured.

[0019]

EXAMPLES The manufacturing method of the present invention comprises a seal portion forming step,
Substrate bonding process, temporary curing process and main curing process are indispensable requirements, but the bonding process for bonding two substrates via spacer means is performed in vacuum and pressure is applied to create a uniform gap. By using, for example, atmospheric pressure as a means,
It is possible to not only provide a cell in which the substrate is uniformly pressed and the stress applied to the substrate is not biased and the gap is uniform, but also a problem such as peeling after the temporary curing of the sealing material by ultraviolet rays can be solved.

Further, when pressing at atmospheric pressure as in vacuum packaging, for example, the substrate is misaligned due to the contraction of the bag, but since the pressure means is only atmospheric pressure, it is uniform over the entire substrate. The pressure is applied to the substrate to prevent misalignment of the substrate.

As the method of forming the seal portion in the step of forming the seal portion of the present invention, a usual method such as a method of applying a seal material to a predetermined portion using a screen printing method or the like can be applied.

As the method of the dropping step of dropping the liquid crystal material of the present invention, for example, a liquid ejecting method such as a dispenser or a method of mechanically or thermally applying pressure to the enclosed liquid crystal material to eject the liquid crystal material from minute holes is used. Applicable.

As the spacer material, for example, glass fiber,
Any material that can define the substrate gap such as resin particles and glass particles may be used. The spacer material may be included in the sealing material or only in the effective display portion, but both in the sealing material and the effective display portion. It is preferable to use a predetermined spacer material in order to make the substrate gap uniform.

The resin of the sealing material applied to the present invention may be any resin as long as it has an ultraviolet curable component and a thermosetting component, and the ultraviolet curable component is a liquid crystal material or a liquid crystal material having radical polymerizability. It is preferable because it has little interaction with the component that aligns the liquid crystal material. From the viewpoint of reactivity, adhesive strength, gas or moisture barrier property, for example, a bisphenol A type vinyl ester acrylate oligomer manufactured by Showa High Polymer Co., Ltd. SP-1563 or SP
A polyfunctional acrylate resin or a polyfunctional methacrylate resin such as 1519 is preferable.

The material of the sealing material of the present invention is as follows.
Needless to say, for example, a predetermined amount of ultraviolet ray or heat polymerization initiator, sensitizer, reactive diluent, polymerization accelerator, etc. may be mixed.

The thermosetting agent for the sealing material of the present invention is, for example, Epicure Z manufactured by Yuka Shell Epoxy Co., Ltd.
Alternatively, amine series such as Epicure 150, for example, hydrazide series such as VDH, UDH or LDH manufactured by Ajinomoto Co., Inc., Epicure E manufactured by Yuka Shell Epoxy Co., Ltd.
An imidazole compound such as MI-24, for example, an acid anhydride such as Epicure YH-306 manufactured by Yuka Shell Epoxy Co., Ltd. does not interact with the liquid crystal or a component having a function of aligning the liquid crystal, and is heated. It is also preferable in terms of temperature.

A method of manufacturing a liquid crystal display device according to an embodiment of the present invention will be described below with reference to the drawings.

Example 1 An example of a method of manufacturing a liquid crystal display device according to the present invention will be described. FIG. 1 is a perspective view for explaining a substrate bonding process in a vacuum chamber. Of the two substrates with electrodes subjected to the orientation treatment, the substrate 1A in which the glass fiber spacer material 2 for controlling the cell gap is scattered and arranged on one side, and the other is the ultraviolet curing component mixed with glass fibers and heated. A substrate 1B formed by screen printing a sealing material 3 containing a curing component is fixed by fixing pins 4A to 4D after the substrate alignment is completed, and the two substrates are separated by spacer plates 5A and 5B which can be taken in and out. It is supported so that it does not come into contact until an arbitrary vacuum state is reached.

In this state, the vacuum chamber 6 is depressurized,
When reaching about 1.0 to 0.4 Torr, the spacer plates 5A and 5B are pulled out from between the two substrates 1A and 1B and attached.

Thereafter, the vacuum chamber 6 is leaked, and the bonded substrates are pressurized at atmospheric pressure to produce the cell 7. At this time, since the atmospheric pressure is uniformly applied to the entire surface of the substrate, there is no bias in stress, a uniform cell gap can be obtained, and a highly accurate cell with no alignment deviation can be obtained.

Next, as shown in FIG. 2, the display portion of the produced cell is shielded by the ultraviolet mask 8 and only the sealing portion is irradiated with ultraviolet rays to temporarily cure the sealing material 3. After that, heat curing is further performed in order to further improve the adhesiveness of the sealing material.

As described above, by using the sealing material that uses both ultraviolet curing and heat curing, and temporarily preparing the seal with ultraviolet rays after the cell is manufactured, there is a possibility that the seal hangs or breaks as shown in FIG. It has a good linearity that does not occur. Further, the main curing by heating gives a seal having excellent adhesiveness and moisture resistance.

Finally, the cell 7 for which the main curing has been completed is cut so that the necessary electrode terminal portions are left as shown in FIG. 3, and the liquid crystal is injected from the injection port 9 in a vacuum and sealed to complete a liquid crystal cell. .

The alignment of the thus-prepared liquid crystal cell at the time of sealing is prevented from spreading on the alignment film by temporarily curing the seal with ultraviolet rays to improve the polymerization degree of the sealing material and increase its viscosity. Because of that it was good.

Example 2 Another method of manufacturing a liquid crystal display device of the present invention will be described. As shown in FIG. 5, of the two electrode-attached substrates that have been subjected to the orientation treatment, one substrate is formed with a sealing material 3 containing a glass fiber-containing UV-curing component and a heat-curing component by screen printing. Then, a required amount of liquid crystal is dropped onto the display area surrounded by the seal material 3 using the liquid ejecting device 11 of the dispenser.

The substrate 1C on which the liquid crystal has been dropped in this manner and the opposite substrate 1A on which the spacer material 2 is arranged are placed in a vacuum chamber as shown in FIG. Then, when the atmospheric pressure in the tank reaches 1 Torr, the spacer plates 5A and 5B are released, and the two substrates 1A and 1C are bonded together.

After that, the pressure is further reduced to 0.4 Torr or less, the inside of the vacuum chamber is leaked and the pressure is applied by the atmospheric pressure, and a uniform cell gap is generated while spreading the liquid crystal material, and the cell 11 to which the liquid crystal is supplied is discharged. Create.

At this time, if the main material of the sealing material is acrylate-based and methacrylate-based, which undergoes radical polymerization during ultraviolet curing, even if the liquid crystal material and the uncured sealing material come into contact with each other at room temperature, for example, If it is a short time such as 5 minutes or less, the display characteristics are not affected.

As shown in FIG. 2, the liquid crystal-containing cell thus produced has its display section shielded by an ultraviolet mask 8.
UV irradiation is applied only to the seal portion to perform temporary curing. At this time, if the ultraviolet rays are sufficiently cured, not only will the sealing material not swell and spread due to subsequent heating and curing of the sealing material, but also the sealing material will not elute into the liquid crystal. .

In this case, the heating temperature is preferably about 120 ° from the transition temperature of the liquid crystal material used to the isotropic phase, and heating above that temperature may cause decomposition of the liquid crystal material, for example. is there. Further, if the heating is performed in the isotropic phase or lower, marks or unevenness of liquid crystal may be generated, which may affect display characteristics.

Therefore, the thermosetting material for the sealing material is 1
Amines, hydrazides, which polymerize at around 20 °
It is preferable to appropriately select and use a material that does not affect the liquid crystal material from the materials such as imidazole and acid anhydride.

[0042]

As described above, according to the present invention, at least one electrode side substrate end portion of a liquid crystal display device in which a liquid crystal is sealed between two electrode-attached substrates is provided with an ultraviolet curing component and a heat curing component. And a substrate bonding step of bonding the other substrate via a spacer means, and at least this sealing portion is irradiated with ultraviolet rays to temporarily cure the sealing portion. Since it is a method of manufacturing a liquid crystal display device that includes a temporary curing step that performs a temporary curing step and a main curing step that heats and temporarily cures the seal portion that is heated after the temporary curing step, a uniform cell gap can be obtained and the alignment of the substrate is not aligned. In addition to producing high-precision cells, a liquid crystal display with excellent linearity, adhesiveness, and moisture resistance of the seal part can be obtained, and the number of steps can be reduced, thus achieving great industrial value. It is intended.

[Brief description of drawings]

FIG. 1 is a perspective view of a laminating process according to an embodiment of the present invention.

FIG. 2 is a schematic view of a temporary curing step according to an embodiment of the present invention.

FIG. 3 is a perspective view of a cell manufactured by a manufacturing method according to an embodiment of the present invention.

FIG. 4 is an enlarged view of a main part of a sealing portion of the cell of FIG.

FIG. 5 is a schematic view of a liquid crystal dropping process according to another embodiment of the present invention.

[Explanation of symbols]

1A A substrate with an electrode that has been subjected to an alignment treatment with a spacer material placed 1B A substrate with an electrode that has been subjected to an alignment treatment that has a seal material formed 1C A substrate that has been subjected to an alignment treatment that has been liquid-dropped and supplied to a place surrounded by a seal material 2 Spacer Material 3 Sealing Material 4A Substrate Fixing Pin 4B Substrate Fixing Pin 4C Substrate Fixing Pin 4D Substrate Fixing Pin 5A Spacer Plate 5B Spacer Plate 6 Vacuum Tank 7 Cell Made by the Invention 8 Ultraviolet Mask 9 Pouring Port 10 Orientation Film 11 Liquid Discharge device

Claims (4)

[Claims] 1. A sealing material containing an ultraviolet curable component and a heat curable component is used at the end of the substrate on the electrode side of at least one electrode of a liquid crystal display device in which liquid crystal is sealed between two substrates with electrodes. A seal portion forming step of forming a seal portion by means of, a substrate bonding step of bonding the other side of the substrate via a spacer means, and a temporary curing step of irradiating at least the seal portion with ultraviolet rays to temporarily cure the seal portion, A method of manufacturing a liquid crystal display device, which comprises a main curing step of heating the provisionally cured seal portion after the temporary curing step to fully cure. 2. Between the seal part forming step and the bonding step,
The method of manufacturing a liquid crystal display device according to claim 1, further comprising a dropping step of dropping the liquid crystal. 3. The method for manufacturing a liquid crystal display device according to claim 1, wherein the laminating step is performed in a vacuum. 4. The method for manufacturing a liquid crystal display device according to claim 1, wherein the substrate with electrodes is subjected to an alignment treatment.