JPS5931043B2 - How to remove organic alignment agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing unnecessary organic alignment agents from liquid crystal cells.

Conventionally, when manufacturing a liquid crystal cell using an organic alignment agent, various methods such as spraying, dipping, spin coating, and brush coating have been used to form the organic alignment agent on the electrode substrate. be.

When coating is performed using the above method, the organic aligning agent is usually formed on areas other than the alignment surface in contact with the liquid crystal. These organic alignment agents formed on parts other than the alignment surface of the liquid crystal do not affect the alignment of the enclosed liquid crystal, but they cause the following harm. 1. An organic alignment agent formed on a terminal portion intended for electrical connection with a drive circuit acts as an insulator and makes the electrical connection incomplete, which is not preferable.

2 On the outside of the seal part, in order to electrically connect the common electrode from the electrode substrate to the counter electrode substrate, a conductive substance is interposed at an appropriate place between both electrode substrates, but in this case, the part for this purpose is The organic alignment agent formed thereon acts as an insulator, making the electrical connection incomplete, which is undesirable.

3 After filling the liquid crystal, it is necessary to seal the filling hole with some kind of substance to maintain airtightness.

Organic sealants include epoxy resins, polyolefin resins, polyamide resins, silicone resins, etc., and inorganic sealants include low melting point solders. When using the above-mentioned sealing material, first of all, it is important from the viewpoint of sealing reliability that the sealing material closely adheres well to the glass electrode substrate in the vicinity of the liquid crystal filling hole. Furthermore, when using an inorganic low melting point solder, metallization may be performed in advance as a base treatment, but adhesion between the metal to be metalized and the glass is also important. However, if an organic alignment agent for liquid crystal alignment is formed near the filling hole, the alignment agent will be interposed between the sealing material and the glass, inhibiting the adhesion between the sealing material and the glass. However, the adhesion of the encapsulant to the glass may be reduced, or it may not adhere at all. The reliability of the airtightness of the enclosure hole is significantly reduced.

4. In particular, when manufacturing using an organic alignment agent application method such as a dipping method, the organic alignment agent is also applied to the surface opposite to the electrode surface, and this may cause the polarizing plate to be attached when the polarizing plate is laminated. This is undesirable as it may impede the adhesion of the material.

For reasons 1 to 4 above, in some cases, when applying the organic alignment agent, areas that are not desired to be coated may be masked in advance.

As for these masking methods, when using a spraying method, a window frame may be provided, or when using a dipping method, a spin coating method, a brush coating method, etc., a masking agent may be formed on a predetermined portion by a printing method or the like. In this case, as the masking agent, a polyolefin polymer or the like that can be easily peeled off after application of the alignment agent is used. However, in the printing method, in order to prevent the alignment agent from contaminating the glass end face as described in 3 above, it is necessary to print on the end face. Generally, it is not easy to print on the end face, and if possible, cells should be manufactured without such printing. In addition, aside from the problem of the edge surface, even if partial masking of the glass surface (terminal area, common transfer area, and back side of the glass) is performed by printing methods, it is not easy to mask a large amount at once. , which would require a considerable amount of time,
Not good for work process. As a result of intensive research, the present inventors have completed the present invention by discovering an efficient method for removing organic alignment agents that are coated on areas other than the necessary areas and have an unfavorable effect on cell performance.

That is, the present invention provides an organic aligning agent layer on a pair of electrode substrates, then makes the pair of electrode substrates face each other in a predetermined positional relationship, and forms the inside of a cell container for liquid crystal enclosure between the two substrates. After manufacturing a liquid crystal filling cell container having a liquid crystal filling hole by providing a stand near the area that will become the filling hole in the area where the liquid crystal is to be filled and fixing both substrates via a spacer or a sealing material, it is possible to eliminate the need for an organic alignment agent. The gist of this paper is a method for removing an organic aligning agent, which is characterized by removing a portion using a plasma ashing method.

Hereinafter, the method of the present invention will be explained in detail.

In recent years, plasma has attracted attention as a dry process in semiconductor production, such as for silicon wafer etching and photoresist ashing.

In the present invention, by using the latter ashing oxygen plasma, the organic alignment agent formed in unnecessary parts is removed, and as a method to improve the reliability of the liquid crystal cell, the removal rate and workability are very high. I found something good.

In oxygen plasma, activated plasma-like oxygen acts as an oxidizing agent and attacks the organic alignment agent, so that even substances that are not oxidized under normal conditions are oxidized and decomposed.

The oxygen used for plasma ashing of organic aligning agents can be ozora (contains oxidation oxygen) or oxygen alone, but oxygen has a higher oxygen concentration than ozora, so the working time is shorter. It's short and nice.

Furthermore, when using high-purity oxygen, the ashing rate decreases compared to when ordinary oxygen is used. This is due to H2O vapor, H2, N2, etc., compared to the ashing rate of oxygen plasma.
It is thought that it is related to the fact that it has a catalytic effect. From the above, when using Ozora as the gas used, the cost of the gas used will be cheaper, but the ashing time will be longer, and when oxygen is used, the gas cost will be higher, but the ashing time will be shorter. There are advantages.

Users can decide on these issues by considering overall cost, efficiency, etc. Applicable organic alignment agents include:
As is clear from the principle of plasma ashing, it can be applied to any of organic low-molecular substances, non-crosslinked polymeric substances, crosslinked polymeric substances, etc.

However, in the case of metal-containing organic low-molecular substances and metal-containing organic polymer substances, only the metal components are not turned into gas by the plasma, so they remain on the substrate, but the non-metal components are incinerated, so there is no effect. be. As the organic alignment agent, one having film-forming properties, specifically, for example, polyvinyl chloride,
Polyvinyl acetate, polymethyl methacrylate, polystyrene, polyvinyl alcohol, polyvinyl butyral,
Polymethylcyanoacrylate, polysulfone, polyimide, polyamideimide, polyesterimide, polybenzimidazole, polyamide, polyparaphenyl oxide, polycarbonate, polyacetal, polyethylene, polypropylene, cellulose resin, urea resin, melamine resin, phenolic resin, epoxy resin, Polyester, alkyd resin, urethane resin, resorcinol resin,
Furan resin, silicone resin, fluorine resin, etc., and their copolymers, etc., as well as natural rubber, styrene-butadiene rubber, acrylonitrile butadiene rubber, polychloroprene, polybutadiene, polyisobutylene, polyisoprene, thiol rubber, polyacrylate, etc. Natural or synthetic polymers such as elastomers, other ion exchange resins, surfactants, polymer flocculants, etc. may be used alone or in combination. There are various methods mentioned above, but what is especially advantageous when using the plasma ashing method is that the organic polymer material forming the coating film is cross-linked or non-cross-linked, and is extremely difficult to dissolve in solvents, or is completely soluble. It's about what you don't do.

This is because unnecessary portions of these materials cannot be removed using a solvent after the coating film is formed. A number of advantages and characteristics of the method for removing an organic aligning agent by plasma ashing have been described above, and various adaptation forms will be explained using drawings so that the advantages will be further clarified.

First, FIG. 1 is a front view of a liquid crystal cell, and FIG. 2 is a cross-sectional view of the liquid crystal cell shown in FIG. In these drawings,
Normally, the terminal part 1 is the part where the organic alignment agent should be removed.
, the common transfer portion 2, the end surface 3 near the liquid crystal filling hole, and the front and back surfaces 4 of the cell. In addition, in the drawing,
5 is a liquid crystal, and 6 is a spacer or sealing material. Furthermore, FIG. 3 is a partial perspective view of the liquid crystal cell for showing an enlarged common transfer portion 2, and 7 indicates a conductor such as indium or solder conductive resin. A method for removing portions 1 to 4 shown in the drawings is to provide an organic alignment agent layer on a pair of electrode substrates, then to make the pair of electrode substrates face each other in a predetermined positional relationship, and to remove a layer between the two substrates. As shown in Figure 5, a ridge 9 is provided with a sealing material or the like in the vicinity of the region forming the filling hole in the region forming the inside of the cell container for liquid crystal filling, and the two substrates are fixed via a spacer or a sealing material. If a cell container for liquid crystal sealing having a liquid crystal sealing hole is subjected to plasma treatment after manufacturing, the liquid crystal can be removed without affecting the alignment surface in contact with the liquid crystal.

For example, if a carrier such as that shown in FIG. 4 is used so that the cells do not come into close contact with each other,
It is also possible to remove all at once.

The part 2 is wedged in a space with a width of about 10μ between the glasses, but various experiments have shown that the plasma can be sufficiently removed even in such a recessed area, and that The reliability of electrical connections has increased dramatically.

In addition, in part 3, similar to 2, plasma wrap-around can be seen, and the plasma enters the cell through the liquid crystal filling hole, and the alignment agent in the surrounding area is removed to some extent.
The structure 9 made of a sealing material or the like prevents orientation abnormalities due to plasma intrusion into the cell. or,
Do not treat each part of 1 to 4 at the same time, cover only part 3, treat parts 1, 2, and 4, then remove the covering of part 3, and process 3 under mild conditions. It doesn't matter.

In addition, if it is not necessary to remove the portion 4 with plasma, it is sufficient to use something like a carrier as shown in Fig. 4 to make each cell adhere to each other without separating them. Since a large amount is required, the number of pieces processed at one time also increases.

The methods for removing each part have been described above, but when an organic sealant is used as the sealant, the outer peripheral part of the sealant is also removed at the same time, but if the processing time is kept to an appropriate level,
The alignment agent can be removed without significantly affecting the sealing material. Next, Examples and Comparative Examples of the present invention will be shown and explained in more detail.

As described in detail in the examples above, according to the present invention, cells can be manufactured without masking when applying an organic alignment agent to an electrode substrate, so manufacturing is not only easy but also easy. The heating process prevents alignment abnormalities due to plasma infiltration into the cell, and allows the organic alignment agent to be removed without adversely affecting cell performance.

A polyimide polymer film was formed as an alignment agent on the entire surface of the electrode by spin coating, and after drying, a heat treatment was performed at 250° C. for 30 minutes.

Next, a low melting point glass paste was printed on the seal portion and the ridge of the electrode substrate using a screen printing method, and dried at 200° C. for 10 minutes.

Next, the pair of electrode substrates treated in this way were placed facing each other so that the directions of the alignment treatment were 90 degrees to each other, and
C. for 10 minutes. Thereafter, the cells were placed on a carrier at 5 mm intervals without being brought into close contact with each other, and fixed in a plasma chamber.

Then, the oxygen flow rate was 100CC/MmllmmHgl2O
Plasma ashing treatment was performed for 10 minutes at the output of OW.
Thereafter, conductive resin was filled into the conductive portions from the common electrode substrate to the other electrode substrate, a commercially available liquid crystal was sealed, and the filling hole was sealed with a sealant. In the cell manufactured in this manner, the alignment agent was completely removed from the terminal portion, the underlying electrode was exposed, and the electrical connection with the drive circuit 1 was sufficient.

When a drive circuit was connected to this and its operation was examined, the connection by the conductive resin was completed perfectly and no apparent drop in threshold voltage was observed. On the other hand, the alignment agent on the end face of the encapsulation hole was also removed in an ideal state, and the adhesion of the organic resin (epoxy resin used in this case) used as the sealing material to the glass became strong. . Comparative Example After cleaning the electrode substrate, a 0.5 (!) aqueous solution of polyoxyethylene nonyl phenyl ether was applied thereto, then heated and dried under vacuum, and aligned by rubbing in one direction with a cloth.

Next, a pair of electrode substrates was placed at 110° with a 20μ nylon film interposed so that the orientation direction was 90 degrees.
Heat and pressure bonding was carried out at ℃. Thereafter, Ichisaka's liquid crystal was inserted through the sealing port provided in advance without performing plasma treatment, and the hole was sealed with epoxy resin to produce a liquid crystal cell.

Next, when we connected the cell to a drive circuit and examined the cell, we found that no voltage was applied to the liquid crystal.

In order to investigate the cause, we lightly rubbed the terminal part with an abrasive to remove the alignment agent formed on the electrode substrate, completed the electrical connection between the drive circuit and the terminal part, and then connected it to the drive circuit again. However, the LCD still did not light up.

It was found that the cause of this was that the alignment agent formed at the portion connecting the common electrode to the counter electrode prevented the action of the conductive resin packed in the area.

Also, the epoxy resin used to seal the holes came off when I rubbed it hard with my fingernail.

[Brief explanation of drawings]

Fig. 1 is a front view showing the liquid crystal cell, Fig. 2 is a cross-sectional view of the liquid crystal cell shown in Fig. 1, Fig. 3 is a partial perspective view of the liquid crystal cell to enlarge the common transfer part, and Fig. 4 5 is a perspective view showing the liquid crystal cells arranged in one carrier, and FIG. 5 is a front view of the liquid crystal cell partially showing the vicinity of the filling hole of the liquid crystal cell. 1...Terminal part, 2...Common transfer part, 3...End face near liquid crystal filling hole, 4...
・Cell front and back surfaces, 5...LCD, 6...
・・Sealing material, 9・・・・・Pick up.

Claims (1)

[Claims] 1. An organic aligning agent layer is provided on a pair of electrode substrates, and then the pair of electrode substrates are made to face each other in a predetermined positional relationship, and within a region forming the inside of a cell container for liquid crystal filling between the two substrates. After manufacturing a cell container for liquid crystal filling with a liquid crystal filling hole by providing a stand near the area that will become the filling hole and fixing both substrates via a spacer or a sealant, the unnecessary part of the organic alignment agent is removed by plasma ash. 1. A method for removing an organic aligning agent, characterized by removing it by a chemical conversion method.