JP2008233626A - Manufacturing method of liquid crystal cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a liquid crystal cell such that an adhesion defect on an interface of a sealing material is improved in a sealing stage of the liquid crystal cell and an alignment defect of liquid crystal nearby an injection hole is improved. <P>SOLUTION: The manufacturing method includes a cell formation stage of forming a cell which has a predetermined gap between two transparent substrates, and also has liquid crystal charged inside a seal having the injection hole on one edge side of the transparent substrates and an ultraviolet-ray setting type sealing material applied to the injection hole, and a sealing stage of irradiating the sealing material with ultraviolet rays to cure the sealing material. The sealing stage comprises a sealing material temporary curing stage and a sealing material curing stage. The liquid crystal is held at first temperature to shrink and the unset sealing material is sucked in and irradiated with ultraviolet rays to temporarily set in the sealing material curing stage. Then the temporarily setting sealing material is irradiated with ultraviolet rays at second temperature for primary setting, thus manufacturing the liquid crystal cell. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a liquid crystal cell, and in particular, due to poor adhesion of the sealing material due to insufficient curing of the sealing material in the sealing process of the liquid crystal cell and insufficient curing of the sealing material generated by isotropic treatment. The present invention relates to a method for manufacturing a liquid crystal cell in which poor alignment of liquid crystals is improved.

  In a method for manufacturing a liquid crystal cell, a method for manufacturing a liquid crystal cell in which liquid crystal is injected and a sealing material applied with a sealing material is cooled to UV cure the sealing material drawn from the injection port is known. (For example, refer to Patent Document 1).

Here, a manufacturing method of this conventional liquid crystal cell will be described with reference to FIGS.
FIG. 7 is a plan view showing a cell formation step in the conventional method of manufacturing a liquid crystal cell. FIG. 8 is a plan view showing a sealing step in the conventional method of manufacturing a liquid crystal cell.

  A conventional method for manufacturing a liquid crystal cell includes a cell forming step and a sealing step. In this cell forming step, two transparent substrates are bonded to each other through a seal having an injection port with a predetermined gap. It consists of a substrate bonding step, a liquid crystal injection step for injecting liquid crystal from the injection port, and a sealing material application step for applying a sealing material to the injection port for injecting liquid crystal. At the stage where this cell forming process is completed, a sealing process is performed in which the sealing material applied to the injection port is cured.

  First, as shown in FIG. 7, the two transparent substrates 1 are bonded together with a predetermined gap through the sealing material 3 having the injection port 23 by the substrate bonding step in the cell forming step, and the liquid crystal injection step is performed. Liquid crystal 4 is filled into the gap from the injection port 23 by a vacuum injection method, and an uncured sealing material 5a is applied to the injection port 23 by a sealing material application process.

  After that, as shown in FIG. 8A, the liquid crystal 4 is contracted by the sealing process and the part of the cell into which the liquid crystal 4 is injected is cooled by the latent heat of vaporization of the highly volatile liquid 12, and the ultraviolet rays are contracted. An uncured sealing material 5a made of a curable resin is drawn into the cell. Then, as shown in FIG. 8 (b), the uncured sealing material 5a is irradiated with ultraviolet rays from the light source 7 in a state where the uncured sealing material 5a is drawn into the injection port 23, and completely A cured sealing material 5c is obtained. Through the above process, the sealing step of closing the liquid crystal 4 is completed, and the target liquid crystal cell is completed.

  In this manner, a liquid crystal cell in which the liquid crystal 4 is sealed in a state where the sealing material 5c is sufficiently drawn into the injection port 23 can be manufactured through the cell formation process and the sealing process.

Japanese Patent Laid-Open No. 10-186385 (page 2-3, FIG. 4)

  According to the method for manufacturing a liquid crystal cell described in Patent Document 1, when a liquid crystal cell having a relatively large outer size is manufactured, the hardened sealing material 5c is placed inside the injection port 23 as described above. A liquid crystal cell in which the liquid crystal 4 is sealed in a sufficiently drawn state can be manufactured. However, when an attempt is made to produce a small and thin liquid crystal cell having a small heat capacity, the following problems occur. This problem will be described with reference to FIG. FIG. 9 is an enlarged view of a main part showing a state in the vicinity of an injection port of a thin liquid crystal cell having a small heat capacity, a small external size, and a thin liquid crystal cell manufactured according to a conventional sealing process.

  In the sealing step in the conventional method for manufacturing a liquid crystal cell, as shown in FIG. 8A, if a part of the thin cell with a small outer size is cooled, an uncured sealing material 5a is obtained. However, since it is small and thin, the entire cell including the uncured sealing material 5a is sufficiently cooled. Even if the uncured sealing material 5a is irradiated with ultraviolet rays in this state, the uncured sealing material 5a is cooled together with the liquid crystal 4, and therefore the uncured sealing material 5a is completely cured. Absent.

  Then, after the sealing process is completed in a state where the sealing material is uncured or insufficiently cured, an isotropic treatment (the liquid crystal cell is once heat treated to change the liquid crystal to an isotropic state, from this heated state. If the process of aligning the liquid crystal is performed by gradually cooling, the uncured or uncured sealing material 5c is pushed back by the thermal expansion of the liquid crystal 4 as shown in FIG. Adhesive failure may be caused at the interface between the uncured or insufficiently cured sealing material 5c and at the interface between the two transparent substrates 1 and the uncured or insufficiently cured sealing material 5c. Further, the uncured or insufficiently cured component of the sealing material 5c may be dissolved into the liquid crystal, which may cause liquid crystal alignment disorder 11.

  Since the liquid crystal cell thus formed is not completely sealed at the inlet, if the reliability is insufficient or the external temperature fluctuates, the liquid crystal 4 in the cell has bubbles or the like. May occur. In this way, when an attempt is made to manufacture a thin liquid crystal cell having a small outer size, the manufacturing defect rate tends to increase dramatically, and this problem cannot be ignored.

  Therefore, according to the conventional method of manufacturing a liquid crystal cell, it is essential to confirm the sealing state after the sealing step and to perform an appearance inspection for selecting defective cells.

  Therefore, the present invention solves the above problems, and in the sealing process of the liquid crystal cell, poor adhesion at the interface between the sealing material and the sealing material, the interface between the sealing material and the two transparent substrates, and poor alignment of the liquid crystal near the injection port An object of the present invention is to provide a method for producing a liquid crystal cell with improved characteristics.

  In order to solve the above problems, the liquid crystal cell manufacturing method of the present invention basically has the following constituent elements.

  The method for manufacturing a liquid crystal cell according to the present invention comprises a step of bonding two transparent substrates with a predetermined gap through a sealing material having an injection port, and injecting liquid crystal into the gap from the injection port. A cell forming step in which a sealing material made of an ultraviolet curable resin is applied to the liquid crystal, and the liquid crystal is cooled to the first temperature and contracted to draw a part of the sealing material into the inlet. A sealing material pre-curing step for pre-curing by irradiating with ultraviolet light, and a sealing material for performing main curing by irradiating the pre-cured sealing material with ultraviolet light again after setting to a second temperature higher than the first temperature. It has a material main curing step.

  The method for producing a liquid crystal cell according to the present invention provides a sealing method at a first temperature in the sealing material temporary curing step and the sealing material main curing step even when a thin liquid crystal cell having a small outer size is produced. By performing ultraviolet irradiation on the pore material and ultraviolet irradiation at the second temperature in stages, the interface between the sealing material and the sealing material due to the thermal expansion of the liquid crystal in the isotropic treatment, and the two transparent substrates It is possible to prevent the uncured sealing material from being pushed back at the interface of the sealing material and the contamination of the liquid crystal by the uncured component of the sealing material.

That is, if a liquid crystal cell is prepared by the manufacturing method of the present invention, a cell in which the liquid crystal 4 is sealed in a state where the fully-cured sealing material is sufficiently drawn into the injection port can be obtained. As a result, it is possible to obtain a highly reliable liquid crystal cell in which bubbles are not generated in the liquid crystal even when the external temperature fluctuates.

  In addition, the effect of the method for producing a liquid crystal cell of the present invention becomes significant particularly when the external dimensions of the liquid crystal cell are small and the thickness of the cell is small. The liquid crystal cell manufactured by the conventional manufacturing method was manufactured by the manufacturing method of the present invention, because the manufacturing yield was poor, and the appearance inspection of the sealed state that was performed after the sealing process was completed was essential. Since the liquid crystal cell greatly improves the manufacturing yield, this appearance inspection is not necessary. By improving the manufacturing yield of the liquid crystal cell, the manufacturing work efficiency is also improved.

  The method for producing a liquid crystal cell of the present invention is such that two transparent substrates are bonded to each other with a predetermined gap through a sealing material having an injection port, and after the liquid crystal is injected from this injection port, ultraviolet curing is applied to the injection port. A cell forming step of applying a sealing material made of a mold resin, and by cooling the liquid crystal to the first temperature and shrinking the volume of the liquid crystal, a part of the sealing material was drawn into the inlet. In the state, after the sealing material is irradiated with ultraviolet rays to temporarily cure the sealing material, and the second temperature higher than the first temperature is set, the temporarily cured sealing material And a sealing material main curing step for subjecting the sealing material to main curing by irradiating with ultraviolet rays again. Here, the detail of the said process is demonstrated in order.

  First, the cell forming process will be described. FIG. 1 is a drawing showing a state in which a liquid crystal injection step is performed in a cell formation step in the method for manufacturing a liquid crystal cell of the present invention. FIG. 1 (a) is an upper plan view in this state, (b) is AA sectional drawing of (a) figure. FIG. 2 is a drawing showing the cell after the sealing material applying step in the cell forming step in the method for producing a liquid crystal cell of the present invention.

  The cell formation step in the method for manufacturing a liquid crystal cell of the present invention includes a substrate bonding step, a liquid crystal injection step, and a sealing material applying step, which are performed in the same manner as in the conventional manufacturing method.

  First, the transparent electrode 2a in the two transparent substrates 1 in which the transparent electrode 2a and the alignment film 2b are formed in the cell forming process by the substrate bonding process in the cell forming process shown in FIG. The transparent substrate 1 is bonded via a frame-shaped sealing material 3 with a predetermined gap. Here, the gap between the two transparent substrates 1 is regulated by, for example, a cylindrical or spherical spacer mixed in the sealing material 3.

  Thereafter, in the liquid crystal injection process, the liquid crystal 4 is filled into the inside (gap) of the cell from the injection port 23 formed in the sealing material 3 by the vacuum injection method in the same manner as in the conventional process. Get.

  Next, a sealing material 5a made of an ultraviolet curable resin is applied to the injection port 23 by a sealing agent application step shown in FIG. The sealing material 5a at this stage is in an uncured state. Here, the sealing material 5a made of an ultraviolet curable resin mainly composed of an Allyl system is used.

Next, a sealing process including a sealing material temporary curing process and a sealing material main curing process, which are characteristic portions of the present invention, will be described with reference to FIGS. FIG. 3 is a drawing showing a sealing material temporary curing step in the method for producing a liquid crystal cell of the present invention. FIG. 4 is a drawing showing a sealing material main curing step in the method for producing a liquid crystal cell of the present invention. FIG. 5 is a drawing showing a temperature profile in the vicinity of the inlet (sealing material) in the sealing material temporary curing step and the sealing material main curing step in the liquid crystal cell manufacturing method of the present invention. FIG. 6 is an enlarged view of a main part showing a state in the vicinity of the injection port of the liquid crystal cell formed by the method for manufacturing a liquid crystal cell of the present invention.

  The vertical axis in FIG. 5 indicates “temperature near the injection port (sealing material)”, and the horizontal axis indicates “ultraviolet irradiation time”. Further, between a and b shown in the drawing, the ultraviolet irradiation time in the sealing material temporary curing step is shown, and between cd shows the ultraviolet irradiation time in the sealing material main curing step. However, it should be noted that FIG. 5 only shows an example of how to adjust the temperature in the vicinity of the inlet (sealing material) in the sealing material temporary curing process and the sealing material main curing process.

  As shown in FIG. 3, the apparatus used in the sealing material temporary curing process and the sealing material main curing process is such that a cell filled with liquid crystal 4 is placed in a thermostatic chamber 6, and the entire cell is kept at a predetermined temperature. Furthermore, a light source 7 is provided for pre-curing and main-curing the uncured sealing material 5a.

First, in the sealing material temporary curing step shown in FIGS. 3 and 5, the temperature of the cell is controlled by the thermostatic bath 6 to cool the liquid crystal 4 to the first temperature (for example, −15 ° C.). Then, the volume of the liquid crystal 4 shrinks, and the uncured sealing material 5a made of an ultraviolet curable resin is drawn into the cell (inside the injection port 23). Thereafter, ultraviolet light is applied to the uncured sealing material 5a made of an ultraviolet curable resin drawn into the cell from the light source 7 (irradiation intensity 12 mW / cm ² ) made of a metal halide lamp for 90 seconds (ultraviolet light having a temporary curing period ab). Irradiation time) Irradiation is performed to obtain a sealing material 5b that is temporarily cured with the uncured sealing material 5a drawn into the cell. Here, the liquid crystal 4 expanded at a second temperature higher than the first temperature in the sealing material main curing process (temperature in the sealing material main curing process performed later) is sealed when temporarily cured. It is assumed that the sealing material 5a is temporarily cured to such an extent that the hole state can be maintained.

  Next, with the sealing material main curing step shown in FIGS. 4 and 5, the temperature of the cell is controlled in the thermostatic chamber 6 in a state where the sealing material 5 b is sufficiently drawn and temporarily cured from the inlet 23. The entire cell is adjusted to a second temperature (eg, 25 ° C.). Here, when the temperature changes from the first temperature to the second temperature, the liquid crystal 4 expands, but the surface of the uncured sealing material 5a is temporarily cured in the sealing material temporary curing step, and the sealing material 5b. Thus, since the adhesive force with other members such as the transparent substrate 1 is maintained, problems such as peeling between the sealing material 5b and the other members do not occur. As shown above, the liquid crystal 4 expanded at the second temperature higher than the first temperature (the temperature in the sealing material main curing process to be performed later) is sealed when temporarily cured. This is because the sealing material 5b is temporarily cured to such an extent that the state can be maintained.

Next, ultraviolet light is again applied for 90 sec from the light source 7 (irradiation intensity: 12 mW / cm ² ) made of a metal halide lamp while maintaining the second temperature for the temporarily cured sealing material 5b made of an ultraviolet curable resin. The ultraviolet-ray irradiation time (full curing period cd) is irradiated, and the temporarily cured sealing material 5b is fully cured to obtain a sealing material 5c. The second temperature here is higher than the first temperature, and the curing reaction of the temporarily cured sealing material 5b is sufficiently accelerated by the ultraviolet irradiation of the temporarily cured sealing material 5b. It is essential to set the temperature. That is, if the second temperature slightly higher than the first temperature is a temperature at which the curing reaction of the sealing material 5b is difficult to promote, the sealing material 5b cannot be completely cured, and the state is left as it is. As described above, if the isotropic treatment is performed, alignment disorder occurs in the liquid crystal 4 and the reliability of the liquid crystal cell is lowered.

  In this way, the liquid crystal cell that has undergone the sealing material temporary curing process and the sealing material main curing process has been described with reference to FIG. The poor adhesion of the material 5c and the poor orientation of the liquid crystal 4 due to the uncured component of the sealing material 5c being dissolved into the liquid crystal can be suppressed as much as possible.

Then, the sealing material 5c in the uncured state is pushed back by the liquid crystal 4 as shown in FIG. 6 by the sealing material temporary curing process at the first temperature and the sealing material main curing process at the second temperature. Therefore, the interface between the sealing material 3 and the sealing material 5c or the transparent substrate 1 and the sealing material 5c is securely bonded, and a liquid crystal cell free from liquid crystal alignment defects can be manufactured.

  Therefore, the liquid crystal cell in which the liquid crystal 4 is sealed in a state in which the completely cured sealing material 5c is sufficiently drawn into the injection port 23 by the sealing material temporary curing process and the sealing material main curing process described above. Can be manufactured. And the liquid crystal cell manufactured by this process becomes a highly reliable cell in which generation | occurrence | production of a bubble does not occur. As a result, it becomes possible to produce a stable liquid crystal cell as shown in FIG. 6, and it becomes unnecessary to select a defective liquid crystal cell by a sealed appearance inspection, thereby improving the productivity of the liquid crystal cell.

It is drawing which shows the liquid-crystal injection | pouring process in the cell formation process of the manufacturing method of the liquid crystal cell of this invention. It is drawing which shows the sealing material application | coating process in the cell formation process of the manufacturing method of the liquid crystal cell of this invention. It is drawing which shows the sealing material temporary hardening process in the manufacturing method of the liquid crystal cell of this invention. It is drawing which shows the sealing material main hardening process in the manufacturing method of the liquid crystal cell of this invention. It is drawing which shows the temperature profile of the injection hole vicinity (sealing material) in the sealing material temporary hardening process and sealing material main hardening process in the manufacturing method of the liquid crystal cell of this invention. It is a principal part enlarged view which shows the state of the injection port vicinity of the liquid crystal cell formed with the manufacturing method of the liquid crystal cell of this invention. It is drawing which shows the cell formation process in the manufacturing method of the conventional liquid crystal cell. It is drawing which shows the sealing process in the manufacturing method of the conventional liquid crystal cell. It is a principal part enlarged view which shows the state of the injection port vicinity of the conventional liquid crystal cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2a Transparent electrode 2b Alignment film 3 Sealing material 4 Liquid crystal 5a-5c Sealing material 6 Constant temperature bath 7 Light source 23 Inlet

Claims (1)

In the liquid crystal cell manufacturing method,
Cell formation in which two transparent substrates are bonded to each other with a predetermined gap through a sealing material having an inlet, liquid crystal is injected into the gap from the inlet, and then a sealing material is applied to the inlet Process,
The liquid crystal is cooled and contracted to a first temperature so that a part of the sealing material is drawn into the inlet, and the sealing material is temporarily cured by irradiating the sealing material with ultraviolet rays. Pore material temporary curing step;
A sealing material main curing step in which after the second temperature is set higher than the first temperature, the temporarily cured sealing material is irradiated again with ultraviolet rays to be fully cured. Cell manufacturing method.

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