JPWO2005054938A1 - Manufacturing method of liquid crystal display panel - Google Patents

Abstract

The method for producing a liquid crystal display panel of the present invention includes a sealing material on the main surface of one or both mother glass substrates (1, 2) of two mother glass substrates (1, 2) to be bonded to each other. A sealing material arranging step of arranging (5), a liquid crystal dropping step of dropping the liquid crystal (6) on one of the two mother glass substrates (1, 2), It comprises a laminating step for laminating two mother glass substrates (1, 2) and a heating step for heating the sealing material (5). The heating step is performed by irradiating the sealing material (5) with an electromagnetic wave having a wavelength of 3 micrometers or more and 5 micrometers or less. Thereby, the elution of the sealing material (5) into the liquid crystal (6) can be sufficiently suppressed.

Description

  The present invention relates to a method for manufacturing a liquid crystal display panel, and more particularly to a method for manufacturing a liquid crystal display panel that can sufficiently suppress elution of a sealing material into liquid crystal.

  In the manufacture of liquid crystal display panels, two glass substrates with transparent electrodes and thin film transistor arrays provided in advance on the surface are bonded together with a sealing material in a state of facing each other so as to maintain a very narrow gap of about several μm. It is necessary to fill and seal the liquid crystal within this interval. Here, when a large glass substrate (also referred to as “mother glass substrate”) is used as the material of the substrate, for example, the following liquid crystal sealing method has been adopted for filling and sealing the liquid crystal. .

  First, a sealing material is placed on the mother glass substrate under an atmospheric pressure environment. A sealing material is arrange | positioned along the outer periphery of the area | region which should become a liquid crystal cell of the surface of one mother glass substrate. At that time, the sealing material is not a completely closed ring, but is arranged in a pattern provided with a cut for injecting liquid crystal into the liquid crystal cell, that is, an “injection port”. Each of the seal material patterns is hereinafter referred to as a “seal pattern”. A plurality of seal patterns are arranged on one mother glass substrate. In this state, two mother glass substrates are bonded together and pressed and cured. A substrate in which two mother glass substrates are bonded together and fixed is called a “bonded substrate”. Next, this bonded substrate is divided into a predetermined size so that the inlet of each seal pattern comes to the end, and an empty liquid crystal cell is obtained. A conventional liquid crystal injection technique was applied to the empty liquid crystal cell thus obtained to inject liquid crystal into the interior from the injection port, and the injection port was sealed.

  In the above-described liquid crystal encapsulating method, it is necessary to separately perform the process of bonding the two mother glass substrates to each other and the process of encapsulating the liquid crystal.

On the other hand, a technique (referred to as “liquid crystal dropping method”) disclosed in Japanese Patent Laid-Open No. 63-179323 (Patent Document 1) has been proposed as a method capable of simultaneously performing these two steps. In the liquid crystal dropping method, after the liquid crystal is dropped on the surface of the substrate on which the closed annular seal pattern is formed, the two substrates are bonded together in a vacuum, so that the bonding of the substrates and the sealing of the liquid crystals are performed simultaneously. . More specifically, a sealant is printed on one of the two substrates to be bonded to each other under vacuum, and a liquid crystal is dropped on one of the two substrates. The substrates are bonded together. The ultraviolet curable resin contained in the sealing material is cured by irradiating the sealing material with ultraviolet rays. Next, the thermosetting resin contained in the sealing material is cured by heating and baking the sealing material. Japanese Laid-Open Patent Publication No. 5-232420 (Patent Document 2) discloses a method of heating and firing a sealing material.
JP-A 63-179323 Japanese Patent Laid-Open No. 5-232420

  In this liquid crystal dropping method, as the panel size is reduced and the panel is made thinner, the spreading speed of the liquid crystal on the substrate increases when the liquid crystal is dropped. As a result, the liquid crystal comes into contact with the sealing material quickly. For this reason, there is a problem that the sealing material is cured while the sealing material and the liquid crystal are in contact with each other, and the sealing material is eluted into the liquid crystal. If the sealing material elutes into the liquid crystal, the liquid crystal is contaminated and causes deterioration of the properties of the liquid crystal.

  As a method for suppressing the elution of the sealing material into the liquid crystal to some extent, there is a method of using a sealing material containing a radical reaction type ultraviolet curing material. This method will be described below.

  As described above, the sealing material contains an ultraviolet curable resin and a thermosetting resin. Of these, the ultraviolet curable resin is composed of an acrylic resin and an ultraviolet curable material. Further, the ultraviolet curable material is classified into a cationic reaction type ultraviolet curable material and a radical reaction type ultraviolet curable material depending on the principle of curing. A cationic reaction type ultraviolet curing material has a property that a curing reaction proceeds in a chain manner other than a portion irradiated with ultraviolet rays, and a Lewis acid is generated as a reaction residue. For this reason, the Lewis acid generated by the curing reaction tends to elute into the liquid crystal. On the other hand, in a radical reaction type ultraviolet curable material, a radical of a molecule contained in the ultraviolet curable material is excited only in a portion irradiated with ultraviolet rays to cause a curing reaction. Further, in the case of radical-curing UV curable materials, no reaction residue is generated during the curing reaction. Therefore, if a radical-reactive UV curing material is used, the reaction residue does not elute into the liquid crystal when the UV curing resin is cured by UV irradiation, so that the elution of the sealing material into the liquid crystal can be suppressed to some extent. .

  However, even when a radical reaction type ultraviolet curable material is used as the ultraviolet curable material of the sealing material, the elution of the sealing material into the liquid crystal cannot be sufficiently suppressed. The reason for this will be described below.

  Usually, the thermosetting resin of the sealing material consists of an epoxy resin and an ultraviolet curable material. When the thermosetting resin is cured by heating and baking, the epoxy resin is once softened at a temperature lower than the curing temperature of the thermosetting resin, and when the thermosetting material is softened, the thermosetting material has sufficient fluidity. To do. As a result, the thermosetting material is easily cured uniformly. Thus, the epoxy resin contained in the sealing material was softened at a temperature lower than the curing temperature of the thermosetting resin, and eluted into the liquid crystal together with the thermosetting material. Therefore, elution of the sealing material into the liquid crystal could not be sufficiently suppressed.

  On the other hand, as a method of suppressing the elution of the sealing material into the liquid crystal, the time for which the epoxy resin is softened is shortened by increasing the temperature rise rate of the sealing material, and the epoxy resin is cured quickly. A method is also conceivable. In the above-mentioned Patent Document 2, two mother glass substrates coated with a sealing material and hot plates are alternately laminated, and the entire surface of the mother glass substrate is directly pressed by sandwiching the whole with a pressure jig. A method of heating and increasing the temperature rising rate of the sealing material is disclosed.

  FIG. 4 is a diagram for explaining how heat is transferred in the heating method based on the conventional technology.

  Referring to FIG. 4, two mother glass substrates 101 and 102 are bonded together by a sealing material 105. A cell formed of the two mother glass substrates 101 and 102 and the sealing material 105 is filled with a liquid crystal 106. A hot plate 103 is installed on the surface (the upper part in FIG. 4) of the mother glass substrate 101 on the side where the sealing material 105 is not applied. A hot plate 104 is provided on the surface (lower part in FIG. 4) of the mother glass substrate 102 on the side where the sealing material 105 is not applied. In this manner, the two mother glass substrates 101 and 102 coated with the sealing material 105 and the hot plates 103 and 104 are alternately laminated.

  In the method disclosed in Patent Document 2, as indicated by arrow A, each of the mother glass substrates 101 and 102 is first heated by each of the hot plates 103 and 104. Then, as indicated by an arrow B, heat is transferred from the mother glass substrates 101 and 102 to the sealing material 105, whereby the sealing material 105 is heated to the curing temperature. That is, in order to raise the temperature of the sealing material 105 to the curing temperature, it is necessary to raise the temperature of the mother glass substrates 101 and 102 to the curing temperature of the sealing material 105. For this reason, heating energy is wasted by the heat capacity of the mother glass substrates 101 and 102, and it takes time to raise the sealing material 105 to the curing temperature. As described above, since the epoxy resin softens at a temperature lower than the curing temperature of the thermosetting resin, if it takes time to raise the sealing material 105 to the curing temperature, the softened epoxy resin and the thermosetting material are liquid crystal. It elutes in 106. As a result, with the method disclosed in Patent Document 2, the elution of the sealing material 105 into the liquid crystal 106 could not be sufficiently suppressed.

  Accordingly, an object of the present invention is to provide a method of manufacturing a liquid crystal display panel that can sufficiently suppress the elution of the sealing material into the liquid crystal.

  The liquid crystal display panel manufacturing method of the present invention includes a sealing material disposing step of disposing a sealing material on the main surface of one or both of two glass substrates to be bonded to each other, and two sheets It includes a liquid crystal dropping step for dropping liquid crystal on one of the glass substrates, a laminating step for bonding two glass substrates, and a heating step for heating the sealing material. The heating step is performed by irradiating the sealing material with an electromagnetic wave including a wavelength of 3 micrometers to 5 micrometers.

  According to the method for manufacturing a liquid crystal display panel of the present invention, a part of the electromagnetic wave is transmitted through the glass substrate without being absorbed by the glass substrate, so that the electromagnetic wave is directly applied to the sealing material sandwiched between the two glass substrates. Irradiate and heat the sealant directly. Therefore, since the temperature of the sealing material can be raised to the curing temperature without raising the temperature of the glass substrate to the curing temperature of the sealing material, the temperature raising rate of the sealing material can be increased. As a result, the time during which the sealing material is softened is shortened and the softened sealing material is less likely to be eluted into the liquid crystal, so that the elution of the sealing material into the liquid crystal can be sufficiently suppressed.

  Preferably, in the method for producing a liquid crystal display panel of the present invention, the heating step is performed by irradiating the sealing material with an electromagnetic wave having a wavelength of 4 micrometers to 5 micrometers.

  Thereby, since the electromagnetic wave is more easily absorbed by the epoxy resin contained in the sealing material, the temperature of the sealing material can be raised efficiently.

  In the method for manufacturing a liquid crystal display panel of the present invention, the heating step is preferably performed by irradiating the sealing material with electromagnetic waves through each of the two glass substrates.

  Thereby, since electromagnetic waves are irradiated from both sides of the sealing material sandwiched between the two glass substrates, the temperature of the sealing material can be raised more efficiently.

  According to the method for manufacturing a liquid crystal display panel of the present invention, a part of the electromagnetic wave is transmitted through the glass substrate without being absorbed by the glass substrate, so that the electromagnetic wave is directly applied to the sealing material sandwiched between the two glass substrates. Irradiate and heat the sealant directly. Therefore, since the temperature of the sealing material can be raised to the curing temperature without raising the temperature of the glass substrate to the curing temperature of the sealing material, the temperature raising rate of the sealing material can be increased. As a result, the time during which the sealing material is softened is shortened and the softened sealing material is less likely to be eluted into the liquid crystal, so that the elution of the sealing material into the liquid crystal can be sufficiently suppressed.

It is a figure which shows the manufacturing process of the liquid crystal display panel in one embodiment of this invention. It is sectional drawing for demonstrating the heating method in one embodiment of this invention. It is sectional drawing for demonstrating how the heat | fever is transmitted with the heating method in one embodiment of this invention. It is a figure for demonstrating how heat is transmitted in the heating method based on a prior art.

Explanation of symbols

  1, 2, 101, 102 Mother glass substrate, 3 IR device, 4a, 4b heater, 5,105 sealing material, 6,106 liquid crystal, 7 substrate support pin, 103,104 hot plate.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a manufacturing process of a liquid crystal display panel according to an embodiment of the present invention.

  Referring to FIG. 1, as a substrate pretreatment, for example, a transparent electrode is formed on each of two mother glass substrates having a thickness of 0.7 mm by a sputtering method or a vapor deposition method. Are cleaned (S1). Subsequently, a liquid crystal alignment material is applied on each of the transparent electrodes by a method such as offset printing, and an alignment film is formed through provisional baking and main baking (S2). Next, each alignment film is subjected to an alignment process by rubbing (S3). Thereafter, each of the two mother glass substrates is washed with water in order to remove foreign matters and dirt on the surface (S4).

  Next, a sealant is printed (arranged) around the surface of one mother glass substrate by a dispenser drawing method, a screen printing method, or the like (S5). As the sealing material, for example, an ultraviolet curable resin in which an ultraviolet curable material is mixed with an acrylic resin or the like and a thermosetting resin in which an epoxy resin or the like is mixed with a thermosetting material, for example, are used. Is preferably used as the sealing material. Further, an ultraviolet curable resin for temporary fixing is applied to a corner portion or the like of at least one mother glass substrate. Further, a spacer for forming a gap is disposed on the surface of at least one mother glass substrate (S6). For example, a spacer having a thickness of 5 μm is used.

  Subsequently, the liquid crystal is dropped into the cells separated by the sealing material (S7). The amount of liquid crystal dripped into the cell is calculated from the area of the portion delimited by the sealing material and the gap of the cell after bonding. The amount of liquid crystal dripped at a time is preferably the minimum amount that can sufficiently obtain the accuracy of the amount of liquid crystal dripped, and the amount of liquid crystal dripped onto the cell is preferably determined by the amount. Moreover, it is preferable to increase the number of liquid crystal dropping points as the cell size increases, and it is preferable to increase the number of liquid crystal dropping points as the cell gap after bonding is narrow. Thereby, the diffusion of the liquid crystal can be made uniform in the cell. In the present embodiment, the liquid crystal was dropped into 12 points for a cell having a size of 6.5 inches.

  Next, two mother glass substrates are positioned and bonded together in a vacuum. The bonding at this time is a state in which the sealing material is in contact with each of the two mother glass substrates, and the inside of the cell is completely surrounded by the sealing material. Then, by releasing to atmospheric pressure, two mother glass substrates are pressed at a pressure of 0.1 MPa (S8). Due to this atmospheric pressure, the vacuum portion in the cell decreases, and as the gap between the two mother glass substrates approaches the target value, the liquid crystal spreads and is uniformly distributed in the cell. Subsequently, the two mother glass substrates are temporarily fixed by irradiating the corners of the mother glass substrate with ultraviolet rays. Thereby, when conveying two mother glass substrates in order to harden a sealing material, position shift of two mother glass substrates can be prevented.

  Next, the two mother glass substrates are conveyed to an ultraviolet irradiation device, the sealing material is irradiated with ultraviolet rays, and the sealing material is temporarily cured (S9). Thus, the cell gap can be stabilized uniformly. Thereafter, the sealing material is fully cured (S10). In the present embodiment, the main curing of the sealing material is performed by the following method.

  FIG. 2 is a cross-sectional view for explaining a heating method according to an embodiment of the present invention.

  Referring to FIG. 2, two mother glass substrates 1 and 2 are bonded together by a sealing material 5, and a liquid crystal 6 is formed in a cell formed by the two mother glass substrates 1 and 2 and the sealing material 5. Is filled. Such mother glass substrates 1 and 2 are supported by substrate support pins 7 in an IR (Infrared Radiation) apparatus 3. Heaters 4a and 4b are installed in the upper and lower portions of the IR device 3, respectively. An electromagnetic wave is applied to the sealing material 5 from the upper heater 4 a through the mother glass substrate 1. Further, electromagnetic waves are applied to the sealing material 5 from the lower heater 4 b through the mother glass substrate 2. The electromagnetic waves (infrared rays) emitted from the heaters 4a and 4b of the IR device 3 include a wavelength of 3 μm to 5 μm, and preferably include a wavelength of 4 μm to 5 μm. For example, when the heaters 4a and 4b having an efficiency of about 80% with respect to the radiation energy of an ideal black body based on Planck's law are used, electromagnetic waves having a wavelength of 4 μm to 12 μm are irradiated. The outputs of the heaters 4a and 4b are adjusted so that the temperature of the mother glass substrates 1 and 2 is 120 ° C. The sealing material 5 is heated for 60 minutes, for example.

  In addition, the wavelength range of the irradiated electromagnetic wave can be increased by raising the heating temperature of the mother glass substrates 1 and 2. However, since it is difficult to lower the temperature after reaching the curing temperature of the sealing material 5, the heating temperature of the mother glass substrates 1 and 2 is made constant. Furthermore, the efficiency of the heaters 4a and 4b can be changed depending on the material of the heat sinks sandwiching the heaters 4a and 4b, and the heater 4a is selected by selecting a heat sink material that improves the efficiency of the heaters 4a and 4b. , 4b can broaden the wavelength range of the electromagnetic waves irradiated.

  FIG. 3 is a cross-sectional view for explaining how heat is transmitted in the heating method according to the embodiment of the present invention.

  Referring to FIG. 3, the glass substrate usually has a property of transmitting about 40% of electromagnetic waves having a wavelength of 3 μm or more and 5 μm or less and not transmitting 100% of electromagnetic waves having a wavelength of more than 5 μm. Therefore, as indicated by the arrow A1, about 40% of the electromagnetic waves emitted from the heaters 4a and 4b pass through each of the mother glass substrates 1 and 2 and are directly absorbed by the sealing material 5. Thereby, the sealing material 5 is heated. Here, the epoxy resin has a property of absorbing electromagnetic waves of 2 μm or more and 12 μm or less, and particularly has a property of more easily absorbing electromagnetic waves of 4 μm or more and 5 μm or less. Therefore, the thermosetting resin of the sealing material 5 is an epoxy resin. In the case where it is included, the sealing material 5 can absorb the electromagnetic wave more efficiently by irradiating the electromagnetic wave having a wavelength of 4 μm to 5 μm. Further, as indicated by an arrow A2, the remaining 60% of the electromagnetic waves irradiated from the heaters 4a and 4b are absorbed by the mother glass substrates 1 and 2, respectively. Thereby, the mother glass substrates 1 and 2 are also heated. When the mother glass substrates 1 and 2 are heated, heat is transmitted from the mother glass substrates 1 and 2 to the sealing material 5 as indicated by an arrow B. Thereby, the sealing material 5 is further heated. As described above, the temperature of the sealing material 5 can be quickly raised to the curing temperature.

  Thereafter, a polarizing plate is disposed on the surfaces of the mother glass substrates 1 and 2, and the mother glass substrates 1 and 2 are divided into cells, whereby the liquid crystal display panel according to the present embodiment is completed.

  According to the manufacturing method of the liquid crystal display panel of the present embodiment, about 40% of the electromagnetic waves irradiated from the heaters 4a and 4b pass through the mother glass substrates 1 and 2 without being absorbed by the mother glass substrates 1 and 2. The sealing material 5 can be directly heated by directly irradiating the sealing material 5 with electromagnetic waves. Therefore, the temperature of the sealing material 5 can be increased to the curing temperature without increasing the temperature of the mother glass substrates 1 and 2 to the curing temperature of the sealing material 5, so that the rate of temperature increase of the sealing material 5 can be increased. As a result, the time during which the sealing material 5 is softened is shortened and the softened sealing material 5 is less likely to be eluted into the liquid crystal 6, so that the elution of the sealing material 5 into the liquid crystal 6 can be sufficiently suppressed. .

  In the liquid crystal display panel manufacturing method of the present embodiment, the sealing material 5 is heated by irradiating the sealing material 5 with an electromagnetic wave having a wavelength of 4 μm or more and 5 μm or less.

  Thereby, since the electromagnetic wave is more easily absorbed by the epoxy resin contained in the sealing material 5, the temperature of the sealing material 5 can be efficiently raised.

  In the method for manufacturing a liquid crystal display panel according to the present invention, the sealing material 5 is heated by irradiating the sealing material 5 with an electromagnetic wave through each of the two mother glass substrates 1 and 2.

  Thereby, since electromagnetic waves are irradiated from both sides of the sealing material 5 sandwiched between the two mother glass substrates 1 and 2, the temperature of the sealing material 5 can be raised more efficiently.

  In the present embodiment, the case where a sealing material including an ultraviolet curable resin and a thermosetting resin is used has been described. However, the present invention is not limited to such a case, and at least a thermosetting component is used. It is sufficient that a sealing material containing is used.

  The embodiment disclosed above should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above embodiments but by the scope of claims, and is intended to include all modifications and variations within the meaning and scope equivalent to the scope of claims.

Claims (3)

A sealing material disposing step of disposing a sealing material (5) on the main surface of one or both of the two glass substrates (1, 2) to be bonded to each other;
A liquid crystal dropping step of dropping the liquid crystal (6) onto any one of the two glass substrates (1, 2),
A laminating step of laminating the two glass substrates (1, 2);
A method of manufacturing a liquid crystal display panel comprising a heating step of heating the sealing material (5),
The said heating process is a manufacturing method of a liquid crystal display panel performed by irradiating the said sealing material (5) with the electromagnetic waves containing a wavelength of 3 micrometers or more and 5 micrometers or less.   The method for manufacturing a liquid crystal display panel according to claim 1, wherein the heating step is performed by irradiating the sealing material (5) with an electromagnetic wave having a wavelength of 4 µm or more and 5 µm or less.   The liquid crystal display panel according to claim 1, wherein the heating step is performed by irradiating the sealing material (5) with the electromagnetic wave through each of the two glass substrates (1, 2). Manufacturing method.

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