JP3030001B2 - Method for manufacturing plastic film liquid crystal display element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a plastic film liquid crystal display device, and more particularly to a plastic film liquid crystal display device suitably used as a display for electronic notebooks, personal computers, word processors, etc., which are required to be lightweight and thin. And a method for producing the same.

[0002]

2. Description of the Related Art In a conventional liquid crystal display device, a glass substrate is used as its substrate. This is because there is a step in which the processing temperature reaches 300 to 500 ° C. during the manufacturing process of the liquid crystal display element, and a glass substrate is suitable as a material that can withstand the temperature.

In recent years, as the manufacturing process and the development of materials have progressed, a manufacturing process in which the processing temperature has been lowered to some extent has become possible, and therefore, a plastic film substrate which is lighter and thinner than a glass substrate is being used. For example, there is a polyethersulfone (hereinafter abbreviated as PES) film substrate having no optical anisotropy.

[0004]

As a plastic film substrate, it is necessary to consider whether there is no optical anisotropy, and it has heat resistance, solvent resistance, gas barrier properties, surface flatness, dimensional stability, and translucency. It is necessary to satisfy required items such as things. The above PES film substrate satisfies these requirements.

However, the PES film substrate has the following disadvantages.

The thickness of the film which can be supplied stably is 0.1 m
Since the film is mt, the film itself has no rigidity, is difficult to handle, and easily deforms when assembling the liquid crystal display element, and it is difficult to obtain flatness. Therefore, it is difficult to use as a substrate of a super twisted nematic type liquid crystal display element requiring high flatness.

[0007] Even if the thickness of the film is formed to be 0.1 mmt or more, the substrate may have streaks and the thickness of the film may vary. Further, when the substrate is formed to have a thickness of 0.1 mmt or more, the retardation of the substrate increases. Normal,
The retardation of the liquid crystal display element is set in advance in a predetermined range so that the display quality is optimal, and the retardation is determined by the retardation of the liquid crystal layer and the retardation of the substrate. It is determined. However, when the retardation of the substrate increases, the retardation of the entire liquid crystal display element also increases. When the retardation exceeds the above-described setting range, a coloring phenomenon occurs, which adversely affects the display quality of the liquid crystal display device.

Further, since the heat resistance is 150 ° C. at the maximum, the constituent materials of the liquid crystal display element must be fired at a low temperature. Therefore, such a temperature condition is severely restricted for a material formed by a relatively high temperature treatment such as an alignment film.

Further, since it is easily affected by temperature and humidity, it lacks dimensional stability.

[0010] Accordingly, an object of the present invention is to provide a plastic film liquid crystal capable of increasing the thickness of a plastic film substrate in order to improve the handling thereof and preventing a decrease in display quality due to an increase in retardation. An object of the present invention is to provide a method for manufacturing a display element.

[0011]

According to a first aspect of the present invention, there is provided a method of manufacturing a plastic film liquid crystal display device having a liquid crystal layer interposed between a pair of plastic film substrates. It is characterized in that the substrate is produced by a mold.

According to a second aspect of the present invention, there is provided a method of manufacturing a plastic film liquid crystal display device according to the first aspect, wherein the mold is formed of polished glass.

Further, the plastic film substrate of the present invention includes a thermosetting acrylic resin having translucency;
Alternatively, a light-transmitting epoxy resin is preferably used.

According to the method of manufacturing a plastic film liquid crystal display device of the present invention, a plastic film substrate is produced by a molding die, and after molding, when adjusting the substrate size or the like again, a cutting step using a cutter or the like is required. In addition, since a step of applying a load to the completed plastic film substrate and possibly causing deformation can be omitted, the plastic film substrate can be manufactured with high accuracy.

Further, since the molding die is formed of polished glass, the surface of the plastic film substrate can be finished with the same precision as polished glass.
The step of polishing the surface again after molding can be omitted.

Also, by using a translucent thermosetting acrylic resin as the material of the plastic film substrate, the plastic film substrate has a streak like a PES film substrate and does not vary in thickness. The substrate can be manufactured with a thickness of 1 mmt or more, for example, 0.2 mmt, and the film itself becomes strong and easy to handle. Further, since the retardation is very small, it does not affect the retardation of the liquid crystal layer, and the display quality is improved. Further, since the heat resistance is improved, the restriction on the processing temperature conditions at the time of forming the alignment film or the like is relaxed, and processing at a higher temperature can be performed. Further, since it is hardly affected by temperature and humidity, dimensional stability is good.

Further, by using a translucent epoxy resin as a material of the plastic film substrate,
A substrate can be manufactured with a thickness of 0.1 mmt or more, for example, 0.2 mmt, without causing streaks or variations in thickness as in a PES film substrate,
The film itself becomes stiff and easy to handle. Further, since the retardation is minute, the retardation of the liquid crystal layer is not affected, and the display quality is improved. Further, since the heat resistance is improved, the restriction on the processing temperature conditions at the time of forming the alignment film or the like is relaxed, and processing at a higher temperature can be performed. Further, since it is hardly affected by temperature and humidity, dimensional stability is good.

[0018]

FIG. 1 is a sectional view showing the structure of a plastic film liquid crystal display device 1 according to one embodiment of the present invention. Referring to FIG. 1, a liquid crystal display element 1 includes a pair of transparent substrates 2 and 3 having a light-transmitting property. The hard coat layers 4 and 5 are made of an epoxy resin, an acrylic resin, a urethane resin, a melamine resin, an organosilicon resin or an inorganic oxide of 3000 to 60.
A film is formed by spinner coating to a thickness of 00 °.
(Alternatively, a film having a thickness of 2 to 3 μm is formed on both surfaces of the transparent substrates 2 and 3 by a dipping method.)
A baking process is performed at 00 to 150 ° C.

[0019] The opposing surfaces of the transparent substrates 2 and 3, the SiO _X as an undercoat layer 6 150-1000
The transparent conductive films 8 and 9 are further deposited on the
ITO (indium tin oxide) with a film thickness of about 1500Å
Formed by sputtering. Further thereon, top coat layers 10, 11 and alignment films 12, 13 formed by spin coating or printing polyimide to about 500 ° are formed. Next, the liquid crystal material 14 is injected, and the sealing member 1 is formed.
Then, the liquid crystal display element 1 is formed by laminating polarizing plates 16 and 17 on the outer surface.

The transparent substrates 2 and 3 are made of a thermosetting acrylic resin and have a thickness of 0.1 to 1.0 mmt.

Further, since the transparent substrates 2 and 3 are manufactured using a molding die, when adjusting the substrate size and the like again after molding, as in a cutting step using a cutter or the like,
Since a step of applying a load to the completed plastic film substrate and possibly causing deformation can be omitted, the transparent substrates 2 and 3 can be manufactured with high accuracy.

Further, if a molding die is made flat with polishing glass and molded using this mold, the surfaces of the transparent substrates 2 and 3 can be finished to the same precision as that of the polishing glass. Can be omitted.

Further, as described above, since the transparent substrates 2 and 3 are formed of a thermosetting acrylic resin, even if the thickness of the substrate is set to, for example, 0.2 mmt, a streak like a PES film substrate is formed. In addition, there is no variation in the thickness, and since there is a stiffness, handling becomes easy, and single-wafer processing can be performed. Therefore, sufficient flatness can be obtained without causing deformation when assembling the liquid crystal display element 1, and a production line for manufacturing a liquid crystal element using a glass substrate can be used. .

Further, since the retardation is very small, even if the transparent substrates 2 and 3 are formed thick, the retardation of the liquid crystal layer is not affected and the liquid crystal display element 1 is not affected.
Display quality does not deteriorate. Furthermore, since the transparent substrates 2 and 3 have heat resistance, the range of selection of constituent materials of the liquid crystal display element 1 such as the alignment films 12 and 13 requiring high-temperature processing is widened. Further, since the transparent substrates 2 and 3 are hardly affected by temperature and humidity, dimensional stability is good.

FIG. 2 is a sectional view showing the structure of a plastic film liquid crystal display element 18 according to another embodiment of the present invention. This embodiment is similar to the above-described embodiment of FIG. 1, and the same components are denoted by the same reference numerals. The feature of this embodiment is that gas barrier layers 19 and 20 for preventing gas such as oxygen and water vapor from entering the liquid crystal layer are formed on the surface of the liquid crystal display element 18 opposite to the transparent substrates 2 and 3. is there. The gas barrier layers 19 and 20 are appropriately formed when more air-permeability is required according to the use environment, and are formed of polyvinyl alcohol or the like.

Further, as another embodiment, the transparent substrates 2 and 3 of the liquid crystal display element 1 shown in FIG. 1 are formed of an epoxy resin.

Since the transparent substrates 2 and 3 are manufactured using a molding die, a load is applied to the completed plastic film substrate as in a cutting step using a cutter or the like when adjusting the substrate size or the like again after molding. Since steps that may cause deformation can be omitted,
The transparent substrates 2 and 3 can be manufactured with high accuracy.

Furthermore, if a molding die is made flat with polishing glass and molded using this mold, the surfaces of the transparent substrates 2 and 3 can be finished to the same precision as that of the polishing glass. Can be omitted.

As described above, since the transparent substrates 2 and 3 are formed of epoxy resin, the thickness of the substrates is set to, for example, 0.2.
mmt, streaks like PES film substrate,
There is no variation in thickness, and handling is easy because of the stiffness, and single-wafer processing is also possible. Therefore, sufficient flatness can be obtained without causing deformation when the liquid crystal display element 18 is assembled, and a production line for manufacturing a liquid crystal element using a glass substrate can be used.

Further, since the retardation is very small, even if the transparent substrates 2 and 3 are formed thick, the retardation of the liquid crystal layer is not affected, and the liquid crystal display element 1 is not affected.
The display quality of No. 8 does not deteriorate. Further, since the transparent substrates 2 and 3 have heat resistance, the range of selection of constituent materials of the liquid crystal display element 18 such as the alignment films 12 and 13 requiring high-temperature processing is widened. Further, since the transparent substrates 2 and 3 are hardly affected by temperature and humidity, dimensional stability is good.

[0031]

As described above, according to the method of manufacturing a plastic film liquid crystal display device of the present invention, a plastic film substrate is produced by a molding die. Since a step of applying a load to the completed plastic film substrate and possibly causing deformation may be omitted, such as a cutting step using, for example, a plastic film substrate can be manufactured with high accuracy.

Further, the surface of the plastic film substrate can be finished with the same precision as that of polished glass by forming the mold with polished glass.
The step of polishing the surface again after molding can be omitted.

Further, by using a translucent thermosetting acrylic resin as a material of the plastic film substrate, a substrate thickness of 0.1 mmt or more can be secured, and the substrate itself becomes strong and easy to handle. Becomes Therefore,
Even when assembling the liquid crystal display element, it is possible to provide a super twisted nematic mode plastic film liquid crystal display element because sufficient flatness is obtained without deformation.

Further, even if the substrate is formed thick, the retardation is very small, so that the display quality of the liquid crystal display device is improved. In addition, due to heat resistance, processing temperature conditions at the time of forming an alignment film or the like are reduced, and processing at a higher temperature becomes possible. Therefore, the selection range of the constituent materials of the liquid crystal display element such as the alignment film is widened. Furthermore, since it is less susceptible to temperature and humidity than PES, it is possible to provide a plastic film liquid crystal display element with dimensional stability.

By using a translucent epoxy resin as the material of the plastic film substrate,
A substrate thickness of 0.1 mmt or more can be secured, and the substrate itself becomes stiff and easy to handle. Therefore, even when assembling the liquid crystal display element, a sufficient flatness can be obtained without causing deformation, so that it is possible to provide a plastic film liquid crystal display element of a super twisted nematic mode.

Further, since the retardation is very small even when the substrate is formed thick, the display quality of the liquid crystal display device is improved. In addition, due to heat resistance, processing temperature conditions at the time of forming an alignment film or the like are reduced, and processing at a higher temperature becomes possible. Therefore, the selection range of the constituent materials of the liquid crystal display element such as the alignment film is widened. Furthermore, since it is less susceptible to temperature and humidity than PES, it is possible to provide a plastic film liquid crystal display element with dimensional stability.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a plastic film liquid crystal display element 1 according to one embodiment of the present invention.

FIG. 2 is a sectional view showing a configuration of a plastic film liquid crystal display element 18 according to another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1,18 Liquid crystal display element 2,3 Transparent substrate 4,5 Hard coat layer 6,7 Undercoat layer 8,9 Transparent conductive film 10,11 Top coat layer 12,13 Alignment film 14 Liquid crystal material 15 Seal member 16,17 Polarized light Plate 19,20 Gas barrier layer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Makoto Iwamoto 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Prefecture Inside Sharp Corporation (72) Inventor Kyohei Iso 22-22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Sharp Stock In-company (56) References JP-A-61-41122 (JP, A) JP-A-62-105102 (JP, A) JP-A-63-300221 (JP, A) (58) Fields investigated (Int. . ^7, DB name) G02F 1/1333 G02F 1/13 101 G09F 9/30

Claims (2)

(57) [Claims] 1. A method of manufacturing a plastic film liquid crystal display device having a liquid crystal layer interposed between a pair of plastic film substrates, wherein the substrate is manufactured by using a molding die. 2. The method for manufacturing a plastic film liquid crystal display device according to claim 1, wherein said mold is formed of polished glass.