JPH01156718A - Production of liquid crystal display element - Google Patents

Abstract

PURPOSE:To rapidly and easily produce an element having excellent quality by placing a liquid crystal compsn. within the sealing frame of one substrate, superposing both substrates and spreading the compsn. by a pressure reduction, then restoring the atmo spheric pressure and supplying a compsn. for replenishment through a packing port. CONSTITUTION:The liquid crystal compsn. 30 of the amt. of 50-90% of the amt. when the element is completed is placed within the frame of a thermosetting type sealant 20 having the packing port for replenishment on the substrate 11. The two substrates 11, 12 are superposed on each other and the pressure therein is reduced to spread the compsn. 30. The liquid crystal compsn. 31 for replenishment is then disposed in the packing port 21 and the atmospheric pressure is restored to suck the compsn. 31 for replenishment into a disposition chamber 40 through the packing port 21 by utilizing the difference in the air pressure. The packing port 21 is thereafter closed by a thermosetting type closing material 50 which is cured by heating. The time for production is thus reduced by executing the sticking of the two substrates 11, 12 and the spreading of the compsn. 3 with the same stage. The liquid crystal element having a uniform thickness is formed by packing the compsn. 31 for replenish ment into the element without excess or shortage.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing a liquid crystal display element.

[Background of the invention]

Liquid crystal display elements have been used in a variety of application fields in recent years because they have advantages such as low power consumption, low manufacturing cost, light weight and thinness, and easy colorization. It is becoming more and more common.

A liquid crystal display element generally includes a pair of electrode substrates each having an alignment layer, and a liquid crystal composition disposed between the pair of electrode substrates, and conventionally includes a twisted nematic type, a super twisted type, Liquid crystal display elements such as guest-host type, birefringence control type, phase transition type, dynamic scattering type, and ferroelectric type are known.

[Conventional technology]

Conventionally, a pair of electrode substrates, on which electrode layers, driving elements, alignment layers, etc. for driving liquid crystals are provided in advance, are arranged to face each other in parallel using a sealant supported on the peripheral edges of the electrode substrates. In addition to fixing the connection, a notch is made in advance in a part of the sealant, and this notch is immersed in the liquid crystal composition in a vacuum atmosphere. In this state, while gradually returning the atmosphere to normal pressure, the liquid crystal composition is A method is known in which a liquid crystal display element is manufactured by injecting an object from a notch into a placement chamber surrounded by a pair of electrode substrates and a sealant, and then closing the notch with a closing agent.

[Problem that the invention seeks to solve]

However, the above manufacturing method has the following problems.

(2) Since the liquid crystal composition is injected from the beginning through the notch using the pressure difference, the injection process requires a considerable amount of time and has the problem of low production efficiency. This problem becomes particularly serious when the electrode substrate is large.

■As the liquid crystal composition is forcefully injected into the arrangement chamber from the notch, the alignment layer in the vicinity of the notch is likely to be damaged, and as a result, the alignment direction of the liquid crystal composition becomes disordered, and There is a problem that the result display quality deteriorates.

However, recently, a sealant is supported on the periphery of one electrode substrate, a certain amount of liquid crystal composition is placed on the electrode substrate, and the other electrode substrate is bonded to this one electrode substrate in a vacuum. As a result, a technique for manufacturing a liquid crystal display element was proposed (see Japanese Patent Application Laid-open No. 89025/1989).

However, in such technology, it is necessary to set the amount of the liquid crystal composition disposed on the electrode substrate to a certain amount with no excess or deficiency, but the required amount is generally a small amount and it is necessary to weigh out a strictly constant amount. is difficult in practice, and in reality only a few percent
errors inevitably occur. Therefore, if the amount of the liquid crystal composition is too small, voids may be formed in the liquid crystal composition layer, and if it is too large, the liquid crystal composition layer will swell and its thickness will become uneven. In addition, the operation of stacking a pair of electrode substrates, aligning them, and applying pressure uniformly must be performed in a vacuum, which requires special equipment, which increases manufacturing costs and reduces operability. There are some difficulties.

The present invention has been made based on the above circumstances, and provides a method for manufacturing a liquid crystal display element that can quickly and easily manufacture a liquid crystal display element and can also manufacture a liquid crystal display element of excellent quality. It is something.

[Means for solving problems]

The present invention provides a method for manufacturing a liquid crystal display element having a structure in which a liquid crystal composition is sealed between a pair of electrode substrates each having an alignment layer disposed facing each other, and includes the following steps (1) to (6). It is characterized by including.

Step (1) A thermosetting sealant is patterned on at least one electrode substrate having an alignment layer so that a filling opening for a replenishing liquid crystal composition is formed in a portion thereof.

Step (2) A liquid crystal composition in an amount of 50 to 90% of the completed capacity is placed on at least one electrode substrate having an alignment layer.

Step (3) After carrying out the steps (1) and (2), the liquid crystal composition is spread by overlapping and pressing the pair of electrode substrates in a reduced pressure atmosphere, and the liquid crystal composition for replenishing the sealant is added. The portion excluding the filling port of the material is brought into close contact between the pair of electrode substrates, and the pair of electrode substrates and the sealant form a placement chamber for the liquid crystal composition.

Step (4) After carrying out the step (3), the liquid crystal composition for replenishment is placed so as to close the filling port of the liquid crystal composition for replenishment of the sealant, and then the atmosphere is returned to normal pressure, and the pressure difference is utilized. At the same time, the pair of electrode substrates is pressurized, and the liquid crystal composition for replenishment is sucked into the placement chamber from the filling port.

Step (5) After carrying out step (4), the filling port for the liquid crystal composition for replenishment is plugged with a thermosetting plugging agent.

Step (6) After performing step (5), the sealing agent and the closing agent are cured by heating, and the liquid crystal composition is blended into the alignment layer to uniformize the alignment of the liquid crystal composition.

[Function and effect of the invention]

According to the present invention, a liquid crystal composition layer is formed by placing a liquid crystal composition on at least one electrode substrate, overlapping the other electrode substrate thereon, and pressing and spreading the liquid crystal composition. The bonding of the electrode substrates and the filling of the majority of the liquid crystal composition can be performed in the same process, and therefore the manufacturing time can be shortened by simplifying the process.

Then, the amount of the liquid crystal composition placed on one electrode substrate is set to 50 to 90% of the completed capacity, and after bonding the pair of electrode substrates together in a reduced pressure atmosphere, the liquid crystal composition filling port for replenishing the sealant is prepared. Since the liquid crystal composition for replenishment is placed in the chamber and the atmosphere is returned to normal pressure, the pair of electrode substrates are uniformly pressurized due to the pressure difference between the inside and outside of the placement chamber, and the insufficient liquid crystal composition is sucked into the placement chamber. As a result, the arrangement chamber is filled with just the right amount of liquid crystal composition, and a liquid crystal composition layer with a uniform thickness can be formed.

Then, the liquid crystal composition is heated at the same time as the sealing agent and the occluding agent are thermally cured to blend the liquid crystal composition into the alignment layer.
A uniform alignment state of the liquid crystal composition can be obtained. Therefore, there is no need to add a new process for orientation control.

Furthermore, when the liquid crystal composition contains a spacer,
In the step of stacking the electrode substrates, the spacers are dispersed in the arrangement chamber as the liquid crystal composition is spread, so the step of dispersing the spacers can be omitted, and loss due to scattering of the spacers can be prevented. When the spacer is made of organic polymer particles, the organic polymer particles can be easily selected to have a specific gravity similar to that of the liquid crystal composition layer and have a spherical shape, thereby improving the dispersibility of the spacer in the liquid crystal composition. Moreover, when the liquid crystal composition is spread, the spacers are also spread and dispersed, and as a result, the uniformity of dispersion of the spacers in the liquid crystal composition layer is improved.

As described above, according to the manufacturing method of the present invention, a liquid crystal display element with excellent display quality can be manufactured with high production efficiency.

[Specific structure of the invention]

The present invention will be explained in detail below.

In the present invention, a liquid crystal display element having a structure in which a liquid crystal composition is sealed between a pair of electrode substrates each having an alignment layer disposed facing each other is manufactured in the following steps [1) to (6).
Manufactured via.

Step (1) As shown in FIG. 1, a thermosetting seal is formed on one electrode substrate 11 having an alignment layer (not shown) so that a filling port 21 for replenishing liquid crystal composition is formed in a portion thereof. The agent 20 is patterned.

Patterning of the sealant 20 can be performed by, for example, a screen printing method, a dispenser coating method, or the like.

The width and height of the sealant 20 are selected depending on the required thickness of the liquid crystal composition layer, etc. - Although they cannot be generally specified, - for boat fishing, the width is about 0.5 to 2 mm, The height is about 10 to 50 μm.

The sealant 20 may be provided on at least one electrode substrate, but may be provided on both electrode substrates as necessary. At this time, it is preferable that the sealant 20 contains a spacer. This is to ensure that the sealant portion has a uniform layer thickness when the pair of electrode substrates is pressurized in a later step.

Specific examples of the sealant 20 include -wave type epoxy resin, two-part type epoxy resin, acrylic resin, silicone resin, and the like.

In this example, the pattern of the sealant 20 is
2, and the notch 22 forms a filling port 21 for replenishing liquid crystal composition.

The substrate material constituting the electrode substrate ratio 12 is not particularly limited, and various materials can be used.

From the viewpoint of spreading the liquid crystal composition 30 well, it is preferable that the material has some flexibility. Specifically, glass materials such as soda glass, borosilicate glass, and quartz glass;
Plastic materials such as axially oriented polyethylene terephthalate, polyether sulfone, polyvinyl alcohol,
Metal materials such as aluminum and stainless steel can be used. Each of these electrode-substrate ratios 12 is provided in advance with an electrode layer, a driving element, an alignment layer, etc. (not shown) for driving the liquid crystal. These electrode layers,
The driving element and the alignment layer are not particularly limited, and conventionally known ones can be used.

Step (2) As shown in FIG. 2, one electrode substrate 1 on which an alignment layer exists
On top of 1, liquid crystal composition 3 in an amount of 50 to 90% of the completed capacity.
Position 0. Note that the completed capacity refers to the amount of the liquid crystal composition that constitutes the liquid crystal composition layer in the final product. The step (2) may be performed in a normal pressure atmosphere. here,
The normal pressure atmosphere refers to a normal atmosphere of around 1 atmosphere.

Specifically, the liquid crystal composition 30 can be placed on the electrode substrate 11 using a dispenser such as a microsyringe. Note that the liquid crystal composition 30 may be placed at a ratio of 12 to both electrodes and substrates, if necessary.

At this time, the liquid crystal composition 30 may be located at one location on the electrode substrate, but preferably it is distributed and located at multiple locations on the electrode substrate. This is to prevent the spacing between the substrates from becoming non-uniform between areas where liquid crystal is present and areas where there is no liquid crystal when a pair of electrode substrates are stacked together in a later process.

When the amount of liquid crystal composition 30 is too small, the amount of liquid crystal composition lacking increases, and therefore the amount of replenishment liquid crystal composition to be sucked into the arrangement space increases in the subsequent step (4), reducing production efficiency. . On the other hand, if the amount of the liquid crystal composition 30 is too large, problems such as leakage of the liquid crystal composition may occur when the pair of electrode substrates 11 and 12 are bonded together, and the effect of uniform pressurization due to the pressure difference may be insufficient. There is.

It is preferable that the liquid crystal composition 30 contains a spacer in advance. This spacer is used in liquid crystal display elements.
By being located between a pair of electrode substrates 11 and 12,
This is to keep the distance between the electrode substrates 11 and 12 constant. When the liquid crystal composition 30 contains spacers in this way, when the liquid crystal composition 30 is spread, the spacers are also dispersed in the placement chamber 40, so the process of dispersing the spacers can be performed separately and independently. This eliminates the need to add additional components, and the process can be simplified.

Organic polymer particles are particularly preferred as such spacers. That is, since spherical organic polymer particles having a specific gravity similar to that of liquid crystal composition 30 can be easily produced, the use of such organic polymer particles improves the dispersibility of the organic polymer particles in the liquid crystal composition. Therefore, by spreading the liquid crystal composition, the organic polymer particles can be uniformly dispersed within the arrangement chamber 40 with extremely high precision. Therefore, the function as a spacer is greatly improved. The outer diameter of the organic polymer particles is selected depending on the thickness of the liquid crystal composition layer, and although it cannot be generally defined, it is generally about 1 to 15 μm.

Although the advantages of including spacers in the liquid crystal composition have been described here, the present invention is not limited to this specification. A separate process may be added and a liquid crystal composition containing no spacer may be placed on the electrode substrate.Furthermore, glass fiber, alumina fine particles, etc. may be used as the spacer.

The material for the liquid crystal composition 30 is not particularly limited, and materials conventionally used in the technical field can be used. Specifically, for example, nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, ferroelectric liquid crystal, etc. can be used.

Step (3) After carrying out the steps (1) and (2), as shown in FIGS. 3 and 4, the pair of electrode substrates 11 and 12 are overlapped in a reduced pressure atmosphere and pressed together. While spreading the liquid crystal composition 30, the part of the sealing agent 20 excluding the filling port 21 of the liquid crystal composition for replenishment is brought into close contact between the pair of electrode substrate ratios 12, and the sealing agent and the pair of electrode substrate ratios 12 are brought into close contact with each other. 20 to form a placement chamber 40 for the liquid crystal composition 30.

In addition, the reduced pressure 3 atmospheres specifically means 17orr or less, preferably 0.3orr or less. An atmosphere below ITorr.

Step (4) After carrying out the step (3), as shown in FIG. 5, fill the replenishment liquid crystal composition 31 into the replenishment liquid crystal composition filling port 21 of the sealant 20 so as to close it, and then The atmosphere is returned to normal pressure, and the pair of electrode and substrate ratios 12 are pressurized using the pressure difference, and the liquid crystal composition 31 for replenishment is sucked into the placement chamber 40 from the filling port 21. This liquid crystal composition for replenishment 31
has the same composition as liquid crystal composition 30.

Step (5) After carrying out the step (4) and inhaling the insufficient liquid crystal composition, remove the excess replenishment liquid crystal composition 31 by, for example, scattering it with a nitrogen gas blow, and then As shown in FIG. 6, the filling port 21 for replenishing liquid crystal composition
The liquid crystal composition layer 32 is sealed with a thermosetting clogging agent 50.
form.

The thermosetting occluding agent 50 can be supported at a predetermined position by, for example, a coating method. Specific examples of the thermosetting sealant 50 include -wave type epoxy resin, two-component type epoxy resin, and the like.

Step [6] After carrying out the step (5), the sealing agent 20 and the closing agent 50 are cured by heating, and the liquid crystal composition 30 is blended into the alignment layer to make the alignment of the liquid crystal composition layer 32 uniform. do.

Conditions for the heat treatment are appropriately selected depending on the sealing agent 20, the occluding agent 50, the liquid crystal composition 30, the type of alignment layer, and the like.

While performing the above steps (2) to (5), the pair of electrode substrates 11 and 12 are heated to a temperature at which the liquid crystal composition has a sufficiently low viscosity or transitions to an isotropic liquid phase. is preferred. At this time, the heating temperature is such that the viscosity of the liquid crystal composition is sufficiently low, and the viscosity of the sealant slowly increases while performing steps (2) to (4), and the viscosity of the sealant increases slowly during step (5).
) is preferably set to be in a substantially semi-cured state.

By performing such heating, the liquid crystal composition 3G can be spread well, a void-free liquid crystal composition layer 32 can be quickly formed, and the liquid crystal composition for replenishment can be quickly inhaled.

Moreover, since the sealing agent is in a semi-hardened state, the pair of electrode substrates that are uniformly pressurized are temporarily fixed, and a liquid crystal display element having a uniform layer thickness can be stably manufactured.

In addition, in the present invention, as shown in FIGS. 7 and 8, for example, on one electrode substrate 11, when the pair of electrode substrates 11 and 12 are overlapped, it becomes near the sealant 20. The photocurable resin 60 is patterned at the position, and in the step (3), the pair of electrode substrates 11 and 12 are overlapped and brought into close contact with the sealant 20 and the photocurable resin 60, and the photocurable resin is irradiated with light and cured. The pair of electrode substrates 11 and 12 are temporarily fixed with the mold resin 60 in a semi-hardened state, and in the step (4), the pair of electrode substrates 11 is fixed using the pressure difference.
．． The fixed state of the pair of electrode-substrate ratios 12 may be reinforced by irradiating light with the electrodes 12 under pressure to completely cure the photocurable resin 60. FIG. 7 shows an example in which the photocurable resin 60 is patterned in a line shape, and FIG. 8 shows an example in which the photocurable resin 60 is patterned in a dot shape.

By going through such a process, replenishment liquid crystal composition 3
It is possible to improve the smoothness of the suction operation in step 1. That is, the suction of the replenishing liquid crystal composition 31 into the placement chamber 40 is as follows:
This is done by utilizing the difference in air pressure between the inside and outside of the placement chamber 40, and the pair of electrode substrates 11 is
．． 12 is temporarily fixed, replenishment liquid crystal composition 31
This prevents the electrode substrates 11° and 12 from shifting during suction.
The suction process can be carried out smoothly.

Further, as shown in FIGS. 9 to 11, the filling port for the liquid crystal composition for replenishment has a pattern of the sealant 20 consisting of a closed line having a protrusion 23, and the protrusion 23 is connected to a pair of electrode substrates. A filling port 21 for the replenishing liquid crystal composition of the sealing agent 20 may be formed by being exposed from the overlapping portion 11 and 12, and the refilling liquid crystal composition 31 may be placed in this.

〔Example〕

Examples of the present invention will be described below, but the present invention is not limited to these Examples.

<Example 1> A pair of electrode substrates made of soda glass provided with an ITO transparent electrode for driving a liquid crystal and an alignment layer were prepared, and a replenishment part consisting of a notch was formed on the electrode side surface of one of the electrode substrates. A sealant made of a liquid type epoxy resin containing a spacer made of glass fiber and extending in a band shape along the periphery so as to form a filling opening for a liquid crystal composition for use was patterned by screen printing. The width of the sealant is 0.5m
m, and the height is 0.02 mm.

Organic polymer particles (manufactured by Tanezu Fine Chemical Co., Ltd.,
A nematic liquid crystal composition containing an average diameter of 7 μm was placed in an amount corresponding to 85% of the completed capacity.

Note that the above steps were performed in a normal pressure atmosphere (1 atm).

Next, in a reduced pressure atmosphere (0.03 Torr),
The liquid crystal composition is spread by stacking and pressing both electrode substrates so that the surface of the other substrate on the electrode side and the surface of the one electrode substrate on the side on which the liquid crystal composition is positioned face each other. While stretching, the portion of the replenishing liquid crystal composition of the sealant excluding the filling port was brought into close contact between the pair of electrode substrates, and the pair of electrode substrates and the sealant formed a placement chamber for the liquid crystal composition.

Next, while maintaining the reduced pressure atmosphere, fill the filling port of the replenishing liquid crystal composition with the replenishing liquid crystal composition so as to block it, then return to the normal pressure atmosphere (1 atm), and use the pressure difference to pair the replenishing liquid crystal composition. While pressurizing the electrode substrate, the liquid crystal composition for replenishment was sucked into the placement chamber from the filling port.

After the filling port of the liquid crystal composition for replenishment is closed with a thermosetting sealant made of a two-component epoxy resin, heat treatment is performed to harden the sealant and the sealant, and the liquid crystal composition is blended into the alignment layer. The alignment of the liquid crystal composition was made uniform.

<Example 2> A liquid crystal display element was manufactured in the same manner as in Example 1 except that the amount of the liquid crystal composition placed on the electrode substrate was changed to 55% of the completed capacity.

Comparative Example 1 A liquid crystal display element was manufactured in the same manner as in Example 1, except that the amount of liquid crystal composition placed on the electrode substrate was changed to 45% of the completed capacity.

Comparative Example 2 A liquid crystal display element was manufactured in the same manner as in Example 1 except that the amount of liquid crystal composition placed on the electrode substrate was changed to 95% of the completed capacity.

(Evaluation) When a driving test was conducted on the liquid crystal display elements obtained as described above, it was found that the liquid crystal display elements obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were all due to poor alignment of the liquid crystal. No deterioration in display quality was observed.

However, in Comparative Example 1, since the amount of liquid crystal composition placed on the electrode substrate was too small, it took about four times as long as in Example 1 to inhale the insufficient amount of liquid crystal composition.

In addition, in Comparative Example 2, since the amount of the liquid crystal composition placed on the electrode substrate was too large, some of the liquid crystal composition got between the electrode substrate and the sealant, resulting in the adhesive strength between the pair of electrode substrates. has decreased.

[Brief explanation of the drawing]

FIGS. 1 to 6 are explanatory diagrams sequentially showing the manufacturing process of the present invention,
FIGS. 7 and 8 are explanatory diagrams showing specific examples of patterning of the photocurable resin, and FIGS. 9 to 11 show main parts of the manufacturing process in other examples of filling ports for replenishing liquid crystal compositions. It is an explanatory diagram. 11... One electrode substrate 12... Other electrode substrate 20... Sealing agent 21... Filling port 22
...Notch part 23...Protrusion part 30...
Liquid crystal composition 31...Replenishment liquid crystal composition 32.
...Liquid crystal composition layer 40...Arrangement chamber 50...Thermosetting type occlusive agent 60...Photocuring type resin 1 Figure
Figure 2 Figure 4 Hand Figure 5 Figure 6 3 otu403220 Figure 7 Figure 9 Figure I1 Figure 8 Clothes Figure 10 20 30 ] 1

Claims (1)

[Scope of Claims] 1) A method for manufacturing a liquid crystal display element having a structure in which a liquid crystal composition is sealed between a pair of electrode substrates each having an alignment layer disposed facing each other, comprising the following steps (1) to Process (6
) A method for manufacturing a liquid crystal display element, the method comprising: Step (1) A thermosetting sealant is patterned on at least one electrode substrate having an alignment layer so that a filling opening for a replenishing liquid crystal composition is formed in a portion thereof. Step (2) A liquid crystal composition in an amount of 50 to 90% of the completed capacity is placed on at least one electrode substrate having an alignment layer. Step (3) After carrying out the steps (1) and (2), the liquid crystal composition is spread by overlapping and pressing the pair of electrode substrates in a reduced pressure atmosphere, and the liquid crystal composition for replenishing the sealant is added. The portion excluding the filling port of the material is brought into close contact between the pair of electrode substrates, and the pair of electrode substrates and the sealant form a placement chamber for the liquid crystal composition. Step (4) After carrying out the step (3), the liquid crystal composition for replenishment is placed so as to close the filling port of the liquid crystal composition for replenishment of the sealant, and then the atmosphere is returned to normal pressure, and the pressure difference is utilized. At the same time, the pair of electrode substrates is pressurized, and the liquid crystal composition for replenishment is sucked into the placement chamber from the filling port. Step (5) After carrying out step (4), the filling port for the liquid crystal composition for replenishment is plugged with a thermosetting plugging agent. Step (6) After performing step (5), the sealing agent and the closing agent are cured by heating, and the liquid crystal composition is blended into the alignment layer to uniformize the alignment of the liquid crystal composition. 2) The method for manufacturing a liquid crystal display element according to claim 1, wherein the liquid crystal composition contains a spacer. 3) The method for manufacturing a liquid crystal display element according to claim 2, wherein the spacer is an organic polymer particle. 4) Patterning a photocurable resin on at least one of the electrode substrates at a position that will be in the vicinity of the sealant when the pair of electrode substrates are overlapped, and in step (3), overlap the pair of electrode substrates. The pair of electrode substrates are temporarily fixed together by applying a backlight to bring the photocurable resin into close contact with the sealant and the photocurable resin, and then temporarily fix the pair of electrode substrates by using the pressure difference in step (4). The liquid crystal display element according to claim 1, characterized in that the substrate is irradiated with light under pressure to completely cure the photocurable resin, thereby reinforcing the fixed state of the pair of electrode substrates. Production method. 5) While performing steps (2) to (5), the pair of electrode substrates is heated to a temperature at which the liquid crystal composition has a sufficiently low viscosity or transitions to an isotropic liquid phase. A method for manufacturing a liquid crystal display element according to claim 1. 6) The liquid crystal according to claim 1, wherein the pattern of the sealant consists of an open line having a cutout, and the cutout forms a filling opening for the liquid crystal composition for replenishment. A method for manufacturing a display element. 7) The pattern of the sealant consists of a closed line having a protrusion, and the protrusion is exposed from the overlapping region of the pair of electrode substrates to form a filling port for the liquid crystal composition for replenishing the sealant. A method for manufacturing a liquid crystal display element according to claim 1.