JP3020068B2 - Manufacturing method of liquid crystal display device - Google Patents

Description

The present invention relates to a method for manufacturing a liquid crystal display device formed by bonding a pair of liquid crystal glass substrates provided with an electrode pattern and an alignment film. The present invention relates to a manufacturing method for easily manufacturing a high-quality liquid crystal display device in a short time and improving workability.

[Conventional technology]

As a method of manufacturing this type of liquid crystal display device, a conventional method is described in US Pat.
The method shown in the figures is known. In FIG. 4A, reference numeral 1 denotes one of a pair of liquid crystal glass substrates provided with an electrode pattern and an alignment film, and first, as shown in FIG. Glass substrate 1
A frame sealant 2 made of a thermosetting adhesive mainly composed of an epoxy resin is formed thereon. At this time, the liquid crystal injection hole 3 is formed in the frame sealant 2 with a part thereof missing.
Next, as shown in FIG. 4 (c), after the other glass substrate 4 is opposed to the frame sealing agent 2 of one glass substrate 1, the frame sealing is performed by heating at a high temperature of 150 ° C. for at least several hours. The agent 2 is cured, whereby a pair of glass substrates 1
4 to form a liquid crystal enclosing cell 5 surrounded by the pair of glass substrates 1 and 4 and the frame sealant 2. As shown in FIG. 4D, a liquid crystal 6 is injected into the cell 5 from the liquid crystal sealing hole 3 in a vacuum, and then the liquid crystal injection hole 3 is sealed to manufacture a liquid crystal display device 7. I do.

[Problems to be solved by the invention]

However, in the above-described manufacturing method, since the frame sealant 2 is a thermosetting adhesive mainly composed of an epoxy resin, it requires a high temperature and a long time for curing, and therefore, the adhesion of the glass substrate due to thermal strain is reduced. As a result, a high-quality liquid crystal display device cannot be obtained due to a drop or a misalignment of the fine pattern.Furthermore, since the liquid crystal is injected from the liquid crystal injection hole into the liquid crystal encapsulation cell in a vacuum, the injection operation is difficult. It is not only troublesome but also requires a long time.

Further, as a method of manufacturing a liquid crystal display device in which the above-mentioned disadvantages are improved, a method using a double sealing method disclosed in JP-A-62-89025 has been proposed. In this method, a radical polymerization type ultraviolet curable resin is used as the inner frame material of the double seal frame, but even when this resin is used, the temperature,
Under severe conditions such as humidity, there are some problems in heat resistance and moisture resistance.

Therefore, an object of the present invention is to provide a method of manufacturing a liquid crystal display device which can improve the workability by manufacturing a high-quality liquid crystal display device simply and in a short time and improve the disadvantages of the above-mentioned known technology. Is to do.

[Means for solving the problem]

In order to achieve the above object, according to the present invention, a pair of liquid crystal glass substrates are attached to each other facing each other with a double frame including an inner frame and an outer frame interposed therebetween, and the pair of substrates and the inner frame are formed. In the method for manufacturing a liquid crystal display device in which liquid crystal is sealed in a space formed by the method, the contact angle between the material and the liquid crystal droplet to be sealed as the inner frame material is
It is characterized by using an organic substance comprising a silicone resin or a fluorine-based resin compound which is at least 35 degrees and insoluble in liquid crystal.

That is, according to the present invention, an inner frame is first formed on the first liquid crystal glass substrate, and the inner frame material has a contact angle between the frame material and the encapsulated liquid crystal droplets of 35. Thermoplastic polymer, thermosetting polymer, UV-curable polymer, or organic material selected from one of moisture-curable polymer having a degree of degree or more, and then use this inner frame The liquid crystal is dropped into the enclosed space on the substrate, and then the second liquid crystal glass substrate is covered on the substrate with an outer frame, that is, a photocurable adhesive, interposed on the outer peripheral edge of the frame, and the second liquid crystal glass substrate is covered with the second liquid crystal glass substrate. The first and second substrates are opposed to each other, and then the photocurable adhesive is irradiated with light to be cured, and then the two substrates are bonded to each other.

As described above, in the present invention, the double frame sealing method is used, and the sealing of the liquid crystal and the bonding of the substrate are simultaneously and integrally formed. In particular, the inner frame material is preferably a liquid having an appropriate fluidity and viscosity suitable for screen printing or dispenser application on a glass substrate,
And, at the time of bonding with the opposing glass substrate, it is necessary to form the inner frame material into a desired size and shape while pressing against the glass substrate. Even if the material is hardened and solidified after bonding, it is essential that the material has appropriate deformability at the time of pressing, and at the same time, has hardness necessary for maintaining the shape. From the above, it can be said that non-solid materials having high viscosity are generally suitable as the inner frame material in the present invention. However, on the other hand, when such an uncured non-solid material is used as a frame material, the liquid crystal material itself is composed of a low molecular weight organic substance when in contact with the liquid crystal to be sealed. The uncured non-solid frame material is very easily eluted and diffused into the liquid crystal phase, or conversely, the liquid crystal penetrates and diffuses into the frame material, causing liquid crystal phase alignment disorder around the interface. It tends to be easy. Therefore, in the present invention, as a result of diligent studies of a countermeasure method for preventing such a failure phenomenon, it is necessary to have a material property such that the elution diffusion into the liquid crystal phase does not easily occur,
It has been found that the following method is appropriate as a condition and a setting method therefor.

That is, specifically, it is extremely effective to measure the contact angle between the frame material and the liquid crystal itself to be sealed as a liquid droplet, and the contact angle obtained by this method is obtained. It has been found that the above-mentioned failure phenomenon hardly occurs when the angle of the object has a certain angle or more.

In general, thermodynamic equilibrium states that whether a solid surface is wet or not by a liquid is determined by the magnitude of the contact angle between the solid surface and the droplet when a small droplet is placed on the solid surface. , Its equilibrium state is Young's equation γ _SV = γ _SL
+ Γ _LV Cosθ, γ _SV to prevent wetting
It is necessary that θ is such that ≦ γ _SL + γ _LV Cos θ is satisfied.

In the above formula, γ _SV … the surface tension of the solid γ _SL … the interfacial tension between the solid and the liquid γ _LV … the surface tension of the liquid In the relationship between the surface tension of the liquid and the contact angle, there is a known to be present in specific critical surface tension ([gamma] c of Zisman), is _{Cosθ = 1 + b (γ C} -γ L) becomes linear relationship between Cos? satisfied.

On the other hand, when a certain substance is dissolved in a liquid, the solubility parameter (SP value) is considered as a characteristic value unique to the object. Those with similar SP values are easily soluble in each other, and one is solid. is the easy wetting when, although different gamma _C value in this SP value also both expression defined above, since both are based on the intermolecular forces, for some synthetic polymers, and gamma _c and SP value It has also been reported that there is a good proportional relationship between them. In other words, as described above, if a certain contact angle between the frame material and the liquid crystal droplet can be obtained as described above, it means that an equilibrium state that does not mix with each other at the interface between the frame material and the liquid crystal is established at the same time. Can also be determined to mean.

According to this method, the contact angles of various frame materials were measured using liquid crystals that are actually commercially available.
If the contact angle is 35 degrees or more, the contact angle hardly changes from the initial contact angle even after a long time. It was confirmed that the liquid crystal phase did not cause alignment disorder even when left unattended.

Table I shows SP values of various polymer materials. (See “Adhesion Handbook,” edited by The Adhesion Society of Japan, page 110.) Of these polymer materials, polyethylene has an SP value of 8.1.
Materials exhibiting near values and thereby exhibiting lower SP values, and thereby materials having lower SP values, may be said to be materials which can be adequately used for this purpose as materials.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a schematic view of a specific example for explaining the method of the present invention. First, as shown in FIG. 2 (a), a first liquid crystal for an electrode pattern and an alignment film is provided. An inner frame 11 is formed on a glass substrate 10 and a substrate surrounded by the inner frame 11
A space 12 is formed on 10. As shown in FIG. 1, the inner frame 11 is an organic substance in which the angle θ between the material a for the inner frame 11 and the liquid crystal b to be sealed is 35 degrees or more and which is insoluble in the liquid crystal. In other words, it is an organic substance that has both softness that can be easily formed at the time of lamination and hardness that can maintain the shape and is insoluble in liquid crystal, and is formed on the substrate 10 by screen printing or the like. The shape of the frame 11 is arbitrary, for example,
The cross section may be circular as shown in FIG. 2 or may be square in cross section as shown in FIG.

Next, as shown in FIG. 2B, a predetermined amount of liquid crystal 13 is dropped into a space 12 on the substrate 10 surrounded by the frame 11 by using a dispenser. In addition, as shown in FIG. 2 (c), a second liquid crystal glass substrate 14 is prepared, and a portion corresponding to the outer peripheral edge 15 of the first liquid crystal glass substrate 10 of the substrate 14 is prepared. Photocurable adhesive 17 is applied to screen 16 by screen printing or dispenser. The second liquid crystal glass substrate 14 is provided with an electrode pattern and an alignment film, similarly to the first liquid crystal glass substrate 10. In addition, the light-curable adhesive 17 is a visible-light-curable adhesive such as ICI L.
CR or an ultraviolet-curing adhesive that is cured by ultraviolet irradiation, for example, World Rock X manufactured by Kyoritsu Chemical Industry Co., Ltd.
−8150.

Next, as shown in FIG. 2 (d), the second liquid crystal substrate 14 formed in FIG. 2 (c) is covered on the frame 11 of the first liquid crystal glass substrate 10 in a vacuum. The first and second substrates 10, 14 are opposed to each other as shown in FIG. At this time, the photocurable adhesive 17 of the second substrate 14
Interposed at the outer peripheral edge 15.

Thereafter, the adhesive 17 shown in FIG. 2 (e) is irradiated with visible light or ultraviolet light, cured, and the two substrates 10 and 14 are bonded to each other to manufacture the liquid crystal display device A according to the present invention.

FIG. 3 is a schematic view of another embodiment of the method of the present invention,
As shown in FIG. 3 (a), similarly to FIG. 2 (a), an inner frame 11 is formed on the liquid crystal substrate 10, and a space 12 is formed on the substrate 10 surrounded by the inner frame 11. .

Next, as shown in FIG. 3 (b), the first substrate
Light-curing adhesive is applied to the outer peripheral edge 15 of the frame 10 in the same manner as in FIG.
After applying 17, as shown in FIG.
A liquid crystal 13 is dropped and injected into the space 12 on the substrate 10 surrounded by the circles in the same manner as in FIG. At this time, as shown in FIG. 3 (b '), the injection of the liquid crystal 13 into the space 12 may be performed before the application of the photocurable adhesive. Next, as shown in FIG. 3 (d), a second liquid crystal substrate 14 is placed on the inner frame 11 of the first liquid crystal glass substrate 10 in a vacuum as in FIG. As shown in FIG. 3 (e), similar to FIG.
And the second substrates 10 and 14 are opposed to each other, and the adhesive 17 is irradiated with visible light or ultraviolet light, cured, and cured.
14 to produce a liquid crystal display device B according to the present invention.

[Action]

According to the present invention described above, since an organic substance having a contact angle of 35 degrees or more between the material and the encapsulated liquid crystal droplets is used as the inner frame material, the softness that can be deformed when the glass substrates are bonded to each other is used. And having a hardness capable of maintaining the shape, and furthermore, since this organic substance is insoluble in the liquid crystal, it does not mix with the liquid crystal, so that the exact dimensions of the frame are not required at the time of bonding the substrates, and The frame formation and the liquid crystal encapsulation can be performed in one step, so that not only the workability is improved, but also a high quality liquid crystal display device is obtained.

Furthermore, according to the present invention described above, by using an ultraviolet curable adhesive, the liquid crystal display device can be moved from room temperature to 100 ° C.
Thus, a high-quality display element free from positional displacement of the fine pattern due to thermal distortion, a reduction in the adhesive strength of glass, and the like can be obtained. Further, the productivity is remarkably improved due to the quick curing property of the ultraviolet curable adhesive.

Further, according to the method of the present invention, it is not necessary to increase the degree of vacuum at the time of sealing the liquid crystal, as compared with the conventional method of injecting liquid crystal from a very narrow liquid crystal injection hole at a relatively high degree of vacuum (liquid crystal display). Since it is sufficient that no air bubbles enter the surface), it is possible to prevent a change in the composition of the liquid crystal composition due to volatilization of the highly volatile component contained in the liquid crystal composition, and at the same time, to encapsulate the liquid crystal in a very short time.

(Example of the invention)

Hereinafter, the present invention will be described specifically with reference to examples.
The present invention is not limited to these examples.

Example First, as a typical liquid crystal, one type of TN type liquid crystal, one type of ZLI-3376-000 (trade name) manufactured by Merck and one type of STN type liquid crystal,
Similarly, ZLI-2293 (trade name) manufactured by Merck was selected.

The contact angle was measured using a contact angle measuring device manufactured by Kyowa Kagaku Co., Ltd. The material for the inner frame to be measured is thinly and uniformly applied on a glass plate to form a test piece, and the liquid crystal droplets are formed on the test piece as shown in FIG. The angle θ formed between the material for use and the droplet was measured, and the measured value was taken as the contact angle of the material for the inner frame.

 Next, the following materials were prepared as inner frame materials.

A. A commercially available product used as a seal frame material for liquid crystal display cells with a thermosetting one-pack type epoxy resin compound: Structbond XN-21-F, Mitsui Toatsu Kogyo Co., Ltd. -Commercially available as an acrylate type glass adhesive: World Lock 815-TN5 manufactured by Kyoritsu Chemical Industry Co., Ltd.-UV-curable one-pack type epoxy resin compound used as a seal frame material for liquid crystal display cells. Commercial product: World Lock X-8700 manufactured by Kyoritsu Chemical Industry Co., Ltd. A commercially available product used as an electrical insulation protection molding agent in a two-part thermosetting type two-component silicone resin compound: manufactured by Shin-Etsu Chemical Co., Ltd. KE109 E-moisture-curable, one-part silicone resin compound used as an insulation protective molding compound for electronic components: Toray Dow Corning Silicone Co., Ltd. A commercial product used as silicone resin grease manufactured by Shin-Etsu Chemical Co., Ltd .: HIVAC-G manufactured by Shin-Etsu Chemical Co., Ltd. Based on fluorinated polymerized oil, containing fluorine-based resin powder, silica anhydride and surfactant A commercially available non-reactive thixotropic fluorine-based compound prepared by addition: World Lock XLC-30 manufactured by Kyoritsu Chemical Sangyo Co., Ltd. H-solvent-soluble fluorine-based copolymer resin Cefural Coat A-10
A fluororesin formulation prepared by dissolving 0 (manufactured by Central Glass Co., Ltd.) at a concentration of about 50% using methylcarbitol as a solvent.

These various materials for the inner frame are thinly and evenly applied on a glass plate to form test specimens as described above, but for materials A to E, the contact angle shall be measured in the state before the curing treatment. , 5 hours at 100 ℃ after coating
After drying for a minute, the test piece was used.

The contact angle was measured for both θ immediately after the formation of the droplet and θ after standing for 5 minutes as it was, and was determined together with the presence or absence of a change with time.

As a comparative example, the contact angle of the glass plate itself and, for some materials, the contact angle when pure water was used as liquid droplets were simultaneously measured and used as a reference.

Next, using these inner frame materials, a double-sealed liquid crystal enclosing panel was prepared by the following method.

First, prepare a glass substrate of length: 20 mm × width: 10 mm, form a hollow inner frame with a line width of 1 mm along the outer edge of the glass substrate by screen printing, and place the liquid crystal almost in the middle of the inner frame. Then, another glass substrate was overlaid on the glass and pressed against it, and the liquid crystal was spread and filled in such a manner that no air bubbles remained in the inner frame, thereby producing a set of panels in which liquid crystal was sealed.

At this time, a spacer was previously mixed into the frame material in order to keep the thickness of the liquid crystal layer at about 8 to 10 μm.

Next, an ultraviolet-curing adhesive is further applied from the outside over the entire periphery of the glass of the panel in which the liquid crystal is sealed, and a mask is applied so that the sealing liquid crystal portion is not irradiated with ultraviolet light. The mold adhesive is cured to form an outer frame,
The double frame seal panel was completed.

Here, the presence or absence of the influence of each of the above-mentioned materials on the liquid crystal, which is the object of the present invention, and the correlation between it and the material properties are described below. The judgment was made based on whether or not the alignment disorder occurred in the liquid crystal phase.

That is, the presence / absence of orientation disorder immediately after the completion of the above-described panel, and then the presence / absence of orientation disorder after the panel was allowed to stand at 65 ° C and 95% relative humidity for 240 hours or more (moisture resistance test). The tendency was examined in comparison with the contact angle of each frame material.

 Table II shows the results.

Among the results in Table II, for the materials E, F, G, and H which did not cause the orientation disorder, the frame shape and dimensions did not change even after the moisture resistance test, and no peeling occurred. Also, from the results in Table II, it is clear that there is a certain relationship between the contact angle and the orientation disorder, and taking into account errors such as measurement, the contact angle is a suitable material for the inner frame material.
It can be concluded that it must have physical properties of 35 degrees or more.

〔The invention's effect〕

As described above, the present invention uses a specific material as the inner frame material, so that a high-quality liquid crystal display device can be manufactured easily and in a short time to improve workability, and is a practically useful method.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a contact angle between an inner frame material and a liquid crystal droplet, and FIGS. 2 and 3 are schematic views for explaining the steps of the present invention, respectively. FIG. 2 is a schematic view showing a conventional process. 10, 14: glass substrate, 11: inner frame, 12: space, 13: liquid crystal, 15: outer peripheral edge of frame, 16: location corresponding to outer peripheral edge of frame, 17: ultraviolet ray effect adhesive, A , B ... Liquid crystal display device.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-26321 (JP, A) JP-A-60-29726 (JP, A) JP-A-60-69634 (JP, A) JP-A-60-69 120320 (JP, A) JP-A-60-146225 (JP, A) JP-A-57-181527 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1339

Claims (1)

(57) [Claims] 1. A liquid crystal for bonding a pair of liquid crystal glass substrates from an inner frame and an outer frame via a double frame so as to face each other, and enclosing liquid crystal in a space formed by the pair of substrates and the inner frame. A method of manufacturing a display device, wherein an organic substance composed of a silicone resin or a fluorine-based resin compound insoluble in liquid crystal is used as the inner frame material. A method for manufacturing a liquid crystal display device, wherein a contact angle with a droplet is 35 degrees or more.