JP2008145592A - Liquid crystal panel cell and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal panel cell in which the orientation on a part of an alignment layer is improved. <P>SOLUTION: A manufacturing method of the liquid crystal panel cell made by holding liquid crystal between a pair of substrates comprises: a process (a) of forming the alignment layer on one side substrate of the pair of substrates; a process (b) of applying a solution made by diluting a resin material which has a mesogen structure on a molecular skeleton and has reactive groups capable of reacting with heat or ultraviolet rays on both ends with an organic solvent onto the alignment layer; a process (c) of depositing the resin material onto the alignment layer by evaporating the organic solvent from the applied solution at a room temperature and, thereby, forming a high-alignment layer having alignment ability higher than the alignment layer; and a process (d) of superimposing the other side substrate on which an alignment layer and a high-alignment layer formed on the alignment layer are formed by the same processes as the processes, on the one side substrate such that the high-alignment layer of both substrates face each other, and adhering both substrates. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal panel cell of a liquid crystal display element and a manufacturing method thereof.

  Conventionally, a rubbing method in which polyimide (PI) is applied on one substrate of a pair of glass substrates (provided with a thin film transistor (TFT) or a color filter), and the applied PI film is rubbed with a cloth or the like, or UV light Alternatively, an alignment process is formed by non-contact alignment method by ion beam irradiation, an alignment film is formed, spacer balls are dispersed on the substrate, an adhesive is applied to the periphery of the substrate, and a sealant is formed. There is a liquid crystal display element that is formed by superimposing on another glass substrate on which an alignment film is formed, pressing and fixing, adhering by heating or UV light irradiation, and then injecting liquid crystal.

  However, when the alignment film is formed, the rubbing method may contaminate the alignment film by removing fine particles or fibers from the special form of cloth used for rubbing, and damages the thin film transistor due to static electricity generated during rubbing. There was a problem giving.

  In order to solve this problem, a photo-alignment method that does not generate dust and static electricity has been developed. This method is a non-destructive alignment method, and if the photo-alignment film is irradiated with polarized light, anisotropic photopolymerization occurs and the photo-alignment film becomes oriented, and the liquid crystal is uniformly aligned. That's it.

  However, the above conventional alignment film does not improve the alignment of the alignment film itself.

  An object of the present invention is to provide a liquid crystal panel cell in which the alignment itself of the alignment film portion is improved.

  The present invention is a liquid crystal panel cell in which liquid crystal is sandwiched between a pair of substrates, wherein the pair of substrates has an alignment film and a high-orientation film formed on the alignment film, and the substrates are mutually connected. The highly oriented film is disposed through a liquid crystal so that the highly oriented films face each other, and the highly oriented film is made of a resin material having a mesogenic structure in a molecular skeleton and a reactive group that reacts with heat or ultraviolet rays at both ends, The liquid crystal panel cell is characterized by having higher alignment than the alignment film.

  Also, a method of manufacturing a liquid crystal panel cell in which a liquid crystal is sandwiched between a pair of substrates, (a) a step of forming an alignment film on one of the pair of substrates, and (b) on the alignment film. A step of applying a solution obtained by diluting a resin material having a mesogenic structure in the molecular skeleton and a reactive group that reacts with heat or ultraviolet rays at both ends with an organic solvent, (c) removing the organic solvent from the applied solution at room temperature Evaporating and depositing the resin material on the alignment film to form a highly oriented film having a higher orientation than the orientation film; and The method of manufacturing a liquid crystal panel cell includes a step of superimposing the other substrate on which the orientation film is formed so that both of the high orientation films face each other and bonding them together.

  In the present invention, a liquid crystal panel cell in which the alignment itself of the alignment film portion is improved can be provided.

  Embodiments to which the present invention is applied will be described below. It should be noted that the present invention is not limited to the following embodiments, and it is obvious that various modifications and changes can be made within the scope defined by the claims.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view of a liquid crystal panel cell according to an embodiment of the present invention. As shown in FIG. 1, the liquid crystal panel cell of the present invention has a high orientation made of a crystalline epoxy resin on an orientation film 3 formed on one glass substrate 1 of a pair of glass substrates 1 at least one of which is transparent. An adhesive film 6 is formed, spacer balls 4 are dispersed on the highly oriented film 6, and an adhesive is applied to the peripheral edge of the substrate to form a sealant 5. In the same manner as described above, the other glass substrate on which the highly oriented film 6 is formed on the orientation film 3 is superposed and bonded, and the liquid crystal is sandwiched between the substrates.

  Note that TFTs or color filters (not shown) for actual image display are formed on the pair of glass substrates 1, but they are not directly related to the present invention, so illustration and description thereof are omitted. .

  Hereafter, the manufacturing process of the liquid crystal panel cell of this invention is demonstrated.

  2 to 9 are cross-sectional views showing the manufacturing process of the liquid crystal panel cell according to the embodiment of the present invention. One glass substrate 1 (FIG. 2) of a pair of glass substrates is prepared, and after washing and drying, a polyimide (PI) film 2 which is a polymer material is applied on the substrate (FIG. 3). Next, after baking for 30 minutes at 200 ° C., the rubbing method (FIG. 4) by rubbing the coated PI film 2 with a cloth or the like, or the non-contact alignment method (FIG. 5) by UV light irradiation or ion beam irradiation. An alignment process is performed to form an alignment film 3 having a thickness of about 1000 mm. Note that the film thickness of the alignment film 3 can be in the range of about 500 mm to about 1000 mm.

Next, as shown in FIG. 6, a crystalline epoxy resin solution 8 in which a crystalline epoxy resin is previously dissolved in an organic solvent is applied onto the alignment film 3 after the alignment treatment. In this embodiment, methyl ethyl ketone (hereinafter abbreviated as “MEK”) is used as an organic solvent, and a crystalline epoxy resin YX4000 (registered trademark) manufactured by Japan Epoxy Resin Co., Ltd. is dissolved in the crystalline epoxy. After preparing a saturated solution with a resin concentration of 20%, it was diluted with ethyl alcohol (C ₂ H ₅ OH), and a crystalline epoxy resin solution 8 with a crystalline epoxy resin concentration of 0.1% was used.

  Next, as shown in FIG. 7, the solvent is slowly evaporated at room temperature (for example, 15 to 25 ° C.) to deposit a crystalline epoxy resin on the alignment film 3. Since the crystalline epoxy resin deposited when the solvent slowly evaporates has an elongated molecular structure, it is efficiently aligned in the uniaxial direction under the influence of the refractive index anisotropy of the surface of the alignment film 3 at the time of deposition. Precipitate on the surface. After the solvent is slowly evaporated and the crystalline epoxy resin is precipitated, the epoxy group having a function as an adhesive undergoes a ring-opening reaction by applying heat by leaving it in a heat chamber at 160 ° C. for 6 hours. Alternatively, the crystalline epoxy resins are bonded together to be fixed, and the crystalline epoxy resin is coated on the alignment film 3 to form the high alignment film 6.

  The orientation of the formed highly oriented film 6 will be described later.

  Next, spacer balls 4 are sprayed and an adhesive is applied to the periphery of the substrate to form a sealant 5 (FIG. 8). Next, as shown in FIG. 9, the other glass substrate 1 in which the high orientation film 6 is formed on the orientation film 3 subjected to the orientation treatment and the both high orientation films 6 face each other by the same process as described above. In this way, they are overlapped and fixed with pressure by a jig (not shown), and then bonded by heating or UV light irradiation. Thereafter, liquid crystal is injected and a polarizing plate (not shown) is formed on the outside of the glass substrate 1 to complete a liquid crystal panel cell.

In the present embodiment, a crystalline epoxy resin is used as the material for the highly oriented film 6. Thereby, the alignment of the liquid crystal is made uniform. Further, after applying the crystalline epoxy resin solution onto the alignment film 3, the solvent is slowly evaporated at room temperature, whereby a highly oriented film is obtained. The general formula of the molecular structure of a crystalline epoxy resin that is a biphenyl type epoxy is shown below. The mesogenic portion of the crystalline epoxy resin contains biphenyl.

  In this embodiment, YX4000 (registered trademark) manufactured by Japan Epoxy Resin Co., Ltd., which is a crystalline epoxy resin represented by the general formula of the above biphenyl type epoxy, was used, but various resins represented by the above general formula For example, YX4000H, YL6121H (registered trademark) manufactured by the same company can also be used in the present invention. In addition to crystalline epoxy resins, acrylate resins, allyl resins, and the like can also be used.

Examples of the liquid crystal that can be applied in the present invention include a fluorine-type TN liquid crystal, which is a mixture of a plurality of simple substances having the following structural formula. The structural formula of each single unit is shown below.

  A crystalline epoxy resin as described above is a material having a chemical structure having a glycidyl ether at both ends of a molecule while having a skeleton (mesogen) portion of a liquid crystal molecule, and has both properties of crystallinity and adhesiveness. In the present embodiment, the crystalline epoxy resin deposited by the solvent evaporation step when forming the highly oriented film 6 has an elongated molecular structure, and thus is oriented in the uniaxial direction on the oriented film at the time of deposition. In the present invention, in particular, a film having high orientation can be obtained by slowly evaporating the solvent at room temperature. Thereafter, the epoxy group having adhesiveness is subjected to a ring-opening reaction by heat to improve the adhesiveness with the alignment film, and it is possible to fix the crystalline epoxy resin molecules by bonding with each other.

  The crystalline epoxy resin has an elongated molecular structure as described above, and is similar in shape and size to the liquid crystal constituent molecules described above. Therefore, by depositing these crystalline epoxy materials by evaporation and thinly coating the alignment film surface and orienting the alignment film in a uniaxial direction, the alignment property of the alignment film with respect to the liquid crystal is transmitted, particularly at room temperature. By evaporating the solvent, a film having higher orientation than that of the alignment film can be obtained, and the function of fixing to the surface of the alignment film can be used to improve the long-term reliability. Further, when the coated crystalline epoxy resin is dissolved as an impurity in the liquid crystal, the crystalline epoxy resin and the liquid crystal are similar in shape and size as described above. Will not interfere.

  As the liquid crystal, other liquid crystals can be used as long as they have a similar structure and size to the crystalline epoxy resin as described above.

As the organic solvent for dissolving the crystalline epoxy resin used in the present invention, MEK is used in the present embodiment, but a solvent that is strong enough to roughen the alignment film such as acetone (CH ₃ COCH ₃ ) is used. Except for this, any resin that dissolves the crystalline epoxy resin is applicable.

  Next, the following experiment was conducted on the orientation of the highly oriented film 6. It is known that the refractive index anisotropy of the surface of the liquid crystal alignment film has a correlation with the orientation (alignment force) (2002 Japan Liquid Crystal Society Annual Report: Inoue et al.). Therefore, the refractive index anisotropy of the surface of the liquid crystal alignment film was measured with a liquid crystal alignment film evaluation apparatus (manufactured by Toyo Technica Co., Ltd.). As shown in FIG. 10, the liquid crystal alignment film evaluation apparatus rotates the sample 11 on the turntable 10 360 ° in a horizontal plane, and reflects the reflected light from the sample 11 of the laser light emitted from the laser irradiation unit 12 at that time. This is detected by the detector 13.

  When the IP film that forms the alignment film is formed and rubbing is not performed (condition 1), when the IP film is formed and rubbing is performed and alignment film is formed (condition 2), the IP film is formed and rubbing is performed. The refractive index anisotropy of each surface was obtained when an alignment film was formed and a highly oriented film was further formed on the alignment film (condition 3).

  A 10 × 10 cm glass substrate having a thickness of 0.5 mm was prepared, washed and dried, and then PI (SE7942 manufactured by Nissan Chemical Industries) was applied at 200 ° C. An IP film was formed by firing in 30 minutes (Condition 1). Next, the IP film was rubbed to form an alignment film (Condition 2).

  On the other hand, a crystalline epoxy adhesive (YX4000 manufactured by Japan Epoxy Resin Co., Ltd.) was prepared, and a saturated solution having a crystalline epoxy resin concentration of 20% was prepared with MEK as an organic solvent. Thereafter, a solution having a crystalline epoxy resin concentration of 0.1% was prepared by diluting with ethyl alcohol. Then, a solution having a concentration of 0.1% was dropped on the alignment film formed on the glass substrate, and then the organic solvent was slowly evaporated at room temperature. After evaporation, the film was left to stand in a heat chamber at 160 ° C. for 6 hours to be thermally bonded to form a highly oriented film (Condition 3).

  When the reflection ellipsometer measurement was performed with the liquid crystal alignment film evaluation apparatus under the above conditions 1 to 3, and the refractive index anisotropy of the surface was measured, the results shown in FIG. 11 were obtained. In FIG. 11, two samples are measured. The vertical axis in FIG. 11 indicates the phase shift (phase difference (nm: nanometer)) of the detected polarized light, and the horizontal axis indicates the rotation angle position (°) of the sample. The greater the difference in deviation, the higher the anisotropy of the film surface molecules, and the rod-like molecules of the crystalline epoxy resin are regularly arranged. FIG. 11A shows the refractive index anisotropy of the surface of the IP film in the case of condition 1 without rubbing, but no anisotropy is observed in the refractive index. Of course, the liquid crystal molecules are not aligned. FIG. 11B shows the refractive index anisotropy of the alignment film surface in the case of the rubbed condition 2. Refractive index anisotropy is observed with a 90 ° period of rotation angle. This is thought to be due to the rearrangement of the alignment film surface molecules by rubbing the alignment film surface in the rubbing direction. Oriented along that direction. Further, (c) of FIG. 11 shows a refractive index anisotropy on the surface of the highly oriented film in condition 3 in which a crystalline epoxy resin solution having a crystalline epoxy resin concentration of 0.1% is dropped to form a highly oriented film. Showing gender. It can be seen that the refractive index anisotropy of the surface of the highly oriented film formed by slowly evaporating the organic solvent at room temperature is clearly increased as compared with FIG.

  A highly oriented film was formed by changing the concentration of the crystalline epoxy resin in the solution, and the refractive index anisotropy of the surface was similarly measured by reflection ellipsometry using a liquid crystal alignment film evaluation apparatus. 12A shows a case where the crystalline epoxy tree concentration is 1%, and FIG. 12B shows a case where the crystalline epoxy tree concentration is 3%. In FIG. 12 (a), the refractive index anisotropy of the surface with a period of 90 ° is observed, but in FIG. 12 (b), no significant refractive index anisotropy is observed. This shows that the upper limit of the crystalline epoxy resin concentration of the solution should be less than 3% in order to obtain a good surface refractive index anisotropy.

  As described above, it is already known that the liquid crystal molecular orientation has a correlation with the refractive index anisotropy of the PI film surface. Therefore, the high orientation film has the function of increasing the refractive index anisotropy. It is considered that it has an aligning force higher than that of the rubbed alignment film. As a possible model, when the solvent of YX4000 (crystalline epoxy resin) having a rod-like molecular shape similar to liquid crystal molecules is slowly evaporated and coated, the molecules are regularly aligned on the surface of the alignment film. It is considered that the refractive index anisotropy is increased.

Embodiment 2. FIG.
13-16 is sectional drawing which shows the process of manufacture of the liquid crystal panel cell by another embodiment of this invention. In the present embodiment, a column spacer 4a is used instead of the spacer ball used in the first embodiment. Hereinafter, the process will be described.

  A photosensitive resin is applied by spin coating on one substrate 1 (FIG. 13) of the pair of glass substrates 1, and the solvent of the photosensitive resin is evaporated by pre-baking. Next, UV light is irradiated from above through a mask. The mask applied here has the pattern of the column spacer 4a. The photosensitive resin corresponding to the portion without the mask pattern is softened after irradiation with ultraviolet rays. Subsequently, the softened photosensitive resin is removed by processing with a developing solution. Finally, the remaining photosensitive resin is post-baked. Through the above steps, the column spacer 4a having a height of 3.5 μm is formed (FIG. 15). In the present embodiment, the height of the column spacer 4a is 3.5 μm, but it can be set in the range of 2 to 10 μm depending on the use of the liquid crystal panel cell to be formed.

  Next, as shown in FIG. 15, the alignment film 3 and the high alignment film 6 are formed on the glass substrate 1 and the column spacer 4 a by the same method as in the above embodiment so as to cover the column spacer 4 a.

  Next, as shown in FIG. 16, an adhesive is applied to the high-orientation film 6 on the periphery of the substrate to form the sealant 5, and then the alignment film 3 formed by the same method as in the above embodiment. Then, the other glass substrate 1 having the high orientation film 6 is superposed so that the high orientation film 6 opposes, and after being pressure-fixed by a jig (not shown), it is bonded by heating or UV light irradiation. Thereafter, liquid crystal is injected to form a polarizing plate (not shown) to complete a liquid crystal panel cell.

  For the liquid crystal panel cell formed as described above, the same effect as in the above embodiment was obtained.

It is sectional drawing of the completed liquid crystal panel cell by one embodiment of this invention. It is sectional drawing which shows the manufacturing process of the liquid crystal panel cell by one embodiment of this invention. FIG. 3 is a cross-sectional view showing a manufacturing process of the liquid crystal panel cell following FIG. 2. FIG. 4 is a cross-sectional view showing a manufacturing process of the liquid crystal panel cell following FIG. 3. FIG. 5 is a cross-sectional view showing a manufacturing process of the liquid crystal panel cell following FIG. 4. FIG. 6 is a cross-sectional view showing a manufacturing process of the liquid crystal panel cell following FIG. 5. FIG. 7 is a cross-sectional view showing a manufacturing process of the liquid crystal panel cell following FIG. 6. FIG. 8 is a cross-sectional view showing a manufacturing step of the liquid crystal panel cell following FIG. 7. FIG. 9 is a cross-sectional view showing a manufacturing step of the liquid crystal panel cell following that of FIG. 8. It is a figure which shows the structure of a liquid crystal aligning film evaluation apparatus. It is a figure which shows the measurement result in the liquid crystal aligning film evaluation apparatus for demonstrating the effect in the liquid crystal panel cell by this invention. It is a figure which shows the measurement result in the liquid crystal aligning film evaluation apparatus at the time of changing the crystalline epoxy resin density | concentration of the solution used at the time of highly oriented film formation regarding this invention. It is sectional drawing which shows the manufacturing process of the liquid crystal panel cell by another embodiment of this invention. It is sectional drawing which shows the manufacturing process of the liquid crystal panel cell following FIG. FIG. 15 is a cross-sectional view showing a manufacturing step of the liquid crystal panel cell following FIG. 14. FIG. 16 is a cross-sectional view showing a manufacturing step of the liquid crystal panel cell following FIG. 15.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Glass substrate, 2 IP film, 3 Orientation film, 4 Spacer ball, 4a Column spacer, 5 Sealant, 6 Highly oriented film, 8 Crystalline epoxy resin solution, 10 Turntable, 11 Sample, 12 Laser irradiation part, 13 Detection vessel.

Claims (13)

A liquid crystal panel cell having a liquid crystal sandwiched between a pair of substrates,
The pair of substrates has an alignment film and a high alignment film formed on the alignment film, and the substrates are arranged via a liquid crystal so that the high alignment films face each other,
The highly oriented film is made of a resin material having a mesogenic structure in the molecular skeleton and a reactive group that reacts with heat or ultraviolet rays at both ends, and has a higher orientation than the oriented film.
A liquid crystal panel cell characterized by that.   2. The liquid crystal panel cell according to claim 1, wherein a ball spacer is interposed between the pair of opposed substrates.   The liquid crystal panel cell according to claim 1, wherein the alignment film and the high alignment film on one of the pair of substrates facing each other are formed via a column spacer.   The liquid crystal panel cell according to claim 1, wherein the resin material is a resin in which a mesogen portion of a resin containing a mesogen contains biphenyl.   The liquid crystal panel cell according to claim 4, wherein the resin material is a crystalline epoxy resin.   6. The liquid crystal panel cell according to claim 1, wherein the molecule of the resin material has glycidyl ether at both ends of the molecule. A method of manufacturing a liquid crystal panel cell in which liquid crystal is sandwiched between a pair of substrates,
(a) forming an alignment film on one of the pair of substrates;
(b) on the alignment film, a step of applying a solution obtained by diluting a resin material having a mesogenic structure in the molecular skeleton and having reactive groups that react with heat or ultraviolet rays at both ends with an organic solvent;
(c) evaporating the organic solvent from the applied solution at room temperature to precipitate the resin material on the alignment film, and forming a highly aligned film having higher alignment than the alignment film; and
(d) including a step of stacking the alignment film and the other substrate on which the high-orientation film is formed by the same process as described above, and bonding the two so that both the high-orientation films face each other. A method for producing a liquid crystal panel cell.   8. The method of manufacturing a liquid crystal panel cell according to claim 7, wherein after the step (c), ball spacers are dispersed on the highly oriented film.   8. The method of manufacturing a liquid crystal panel cell according to claim 7, wherein an alignment film is formed on the one substrate via a column spacer in the step (a).   8. The method for producing a liquid crystal panel cell according to claim 7, wherein the resin material is a resin in which a mesogen portion of a resin containing a mesogen contains biphenyl.   The method for manufacturing a liquid crystal panel cell according to claim 10, wherein the resin material is a crystalline epoxy resin.   12. The method for producing a liquid crystal panel cell according to claim 7, wherein the molecule of the resin material has glycidyl ether at both ends of the molecule.   8. The method of manufacturing a liquid crystal panel cell according to claim 7, wherein after the step (a), the alignment film is aligned using one of rubbing, UV irradiation, and ion beam.

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