JPH0720479A - Liquid crystal element and its production - Google Patents

Abstract

PURPOSE:To improve the durability of sealing parts and to prevent the deterioration in performance by infiltration of air bubbles by adhering and fixing a pair of film base materials to each other by a thin adhesive layer on the circumferential outer side of a liquid crystal layer and sealing the liquid crystal layer. CONSTITUTION:Spacers 1 are adhered and fixed by an adhesive resin 40 within a liquid crystal forming region 2a on the surface of the one film base material 2 on the side where an electrode layer 21 is formed and the adhesive layer 4 is formed in the region 2b on the circumferential outer side of the liquid crystal forming region 2a. A liquid crystal material 30 which is the raw material of the liquid crystal layer 3 is held between the film base material 2 and another film base material 2 and these base materials are passed between a pair of laminating rolls R, etc., by which the materials are subjected to a lamination treatment. The space between a pair of the film base materials 2 is held at the prescribed interval by the spacers 1 adhered and fixed within the liquid crystal forming region 2a. The liquid crystal material 30 is packed therein, by which the liquid crystal layer 3 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device used for a TV screen, a display screen for general OA equipment, an automobile display panel, an in-vehicle navigation, etc., a light control glass, a sunroof of an automobile, a sunshade and the like. , The manufacturing method thereof.

[0002]

2. Description of the Related Art Liquid crystalline polymers and low molecular weight liquid crystal materials,
A liquid crystal device has been proposed in which a mixed film containing a minute amount of an electrolyte is sandwiched between a pair of base materials [JP-A-2-1931].
No. 15, JP-A-2-127494, Chem.Let
t., 817 (1989), Polym. Preprints, Japan 39 (8) 2373.
(1990), etc.].

In the above liquid crystal element, when a low frequency or direct current electric field is applied to the mixed film, ions present in a very small amount in the film move together with the electric field and collide with the main chain of the liquid crystalline polymer to cause liquid crystal. Since the arrangement is disturbed, the incident light is strongly scattered, and the mixed film becomes cloudy. On the other hand, when a high-frequency electric field is applied to the mixed film, the liquid crystal molecules in the film are homeotropically oriented in the electric field direction so that the incident light can pass through without being scattered and is converted into a transparent state.

Further, since the type and composition of the components are selected so that the mixed film usually exhibits smectic properties at the operating temperature of the device, a white turbid state is produced when the electric field is removed in both of the above conditions. Alternatively, it has a memory property for stably maintaining the transparent state and performs a bistable optical switching operation. For this reason, the liquid crystal element provided with the above mixed film has an advantage that the active matrix drive using the TFT or the like having a low manufacturing yield is not necessary when the display screen has a large number of pixels, and the TV screen or the like. It can be suitably used for a display element that performs complicated display of.

On the other hand, when the type and composition of the constituents are selected so that the mixed film exhibits nematic properties at the operating temperature of the device, the mixed film becomes cloudy only while an electric field of low frequency or direct current is applied. Therefore, the present inventors have found that when the application is stopped, the switching operation is changed to a transparent state. The mixed film that exhibits such an operation has a fail-safe function that becomes transparent when the electric field is no longer applied to the element due to an accident, failure, etc. It is expected that it can be suitably used as a display element.

Further, as can be seen from the above-mentioned operation mechanism, any of the above-mentioned mixed films does not require a polarizing plate, unlike a conventional liquid crystal element, so that it is easy to see brightly, especially when a reflective display is made. In addition to the advantages, it is possible to impart self-supporting property to the mixed film. Therefore, there is an advantage that flexibility can be imparted to the element by using a flexible transparent film as a substrate.

A flexible liquid crystal device having the above-mentioned mixed film is manufactured by laminating a paste-like mixture in which each component constituting the mixed film is mixed between a pair of film base materials. It

[0008]

Since the mixed film contains the liquid crystalline polymer as described above, it has a high viscosity and a slow response speed. Therefore, in order to improve the response speed, it has been attempted to adjust the types of constituent components and their blending to make the viscosity of the mixed film as low as possible. However, especially when a low-viscosity mixed film is combined with a flexible film substrate, bubbles may enter from the peripheral portion of the element to impair the characteristics of the element, so that strict sealing is required. .

As a normal sealing structure, as shown in FIG. 3, a structure in which a sealing material 91 is raised on the end faces of a pair of film base materials 92 sandwiching the liquid crystal layer 93 is adopted. However, in this structure, the film base material 92 and the sealing material 91 are
The adhesive force is small because they are in contact with each other only at the end face of No. 2, the film base material 92 and the sealing material 91 have a large difference in expansion and contraction rates with respect to heat and moisture, and the sealing material for improving the sealing performance. Since it is necessary to thicken the sealing material 91, the sealing material 91 is likely to come into contact with other members during handling of the element, the sealing material 91 that is thickly stacked becomes rigid, and the like. The element may be peeled off, cracked, or the like to cause insufficient sealing of the element, and as a result, the performance of the element may deteriorate with long-term use. If the rigid sealing material 91 is present in the peripheral portion of the element as described above, the flexibility of the element may be impaired.

Further, when the element is manufactured by the laminating treatment, air bubbles may enter the element after the laminating treatment and before the sealing treatment, and the characteristics of the element may be impaired. The present invention has been made in view of the above circumstances, and in particular, a flexible liquid crystal element which has excellent durability of the sealing portion and does not deteriorate in performance due to bubbles entering the element even after long-term use. Another object of the present invention is to provide a liquid crystal device and a method for manufacturing the liquid crystal device without allowing air bubbles to enter the device during manufacturing.

[0011]

In order to solve the above-mentioned problems, a liquid crystal element of the present invention has a liquid crystal layer in which an edge of the liquid crystal layer is arranged inward from an edge of a film base material, and the periphery of the liquid crystal layer is surrounded. It is characterized in that a region where the pair of film base materials are bonded and fixed to each other by a thin adhesive layer is provided outside the liquid crystal layer and the spacer, and the liquid crystal layer is sealed.

Further, in the manufacturing method of the present invention for manufacturing the liquid crystal element of the present invention, a spacer is bonded and fixed in the liquid crystal layer forming region of at least one surface of the pair of film base materials, and the film is formed. After forming an adhesive layer on at least one of the base material and the other film base material in the area outside the liquid crystal layer forming area, a liquid crystal material is sandwiched between the film base materials and laminated. To do.

In the liquid crystal element of the present invention having the above structure, a pair of film base materials are bonded and fixed to each other in a relatively large area provided outside the periphery of the liquid crystal layer to seal the liquid crystal layer. Therefore, the durability of the sealing portion can be improved. Further, in the sealing region, since the pair of film base materials are adhered and fixed to each other via the thin adhesive layer, there is no fear that the flexibility of the element is impaired.

Further, according to the manufacturing method of the present invention, since the liquid crystal layer is sealed at the same time as the laminating process, it is possible to prevent bubbles from entering the device during manufacturing. The present invention will be described below with reference to the drawings. As shown in FIG. 1 (c), the liquid crystal device of the present invention has a structure in which a liquid crystal material is filled between a pair of film base materials 2 held at a predetermined interval by a spacer 1 to form a liquid crystal layer 3. Have The liquid crystal layer 3 is formed on the surface of each film substrate 2 on the liquid crystal layer 3 side.
An electrode layer 21 for applying an electric field for driving is formed on.

As shown in FIG. 2 (c), the liquid crystal layer 3 has its edges arranged inward of the edges of the film substrate 2. A region where the pair of film base materials 2 are adhered and fixed by the thin adhesive layer 4 without the liquid crystal layer 3 and the spacer 1 is provided outside the periphery of the liquid crystal layer 3 to seal the liquid crystal layer 3. There is. The spacer 1 is made of silica,
It is also possible to mix and disperse a spacer material made of glass fiber or resin and having an arbitrary shape such as a granular shape or a needle shape. The particle size of the spacer 1 is set according to the desired distance between the base materials (that is, the film thickness of the mixed film). The mixing ratio of the spacer material is not limited to this, but it is desirable that it is about 10 to 300 per 1 mm ^{2 of} liquid crystal area.

Examples of the film substrate 2 include polyethylene terephthalate (PET) film and polyether sulfone (PES) film, which are excellent in heat resistance, practical strength and optical uniformity. The thickness of the plastic film is not limited to this, but is preferably about 50 to 500 μm. Film base 2
In the case of a transmissive element, the electrode layer 21 formed on the surface of ITO is ITO (Indium-Tin-Oxide) or Sn.
A transparent conductive film made of a transparent conductive material such as O ₂ is preferably used. The transparent conductive film may be formed by a vacuum deposition method or a reactive sputtering method, or may be formed by applying or printing an ink containing the transparent conductive material on a substrate. When the liquid crystal element of the present invention is used in, for example, a display device or various kinds of illuminations, the above electrode layer is used to divide the liquid crystal layer into a plurality of individually driven segments according to the display pattern. Is patterned into a predetermined shape corresponding to the segment by etching or the like, and a drive circuit may be connected so that an individual drive voltage can be applied to each segment.

As the liquid crystal layer 3, a mixed film composed of the liquid crystalline polymer, a low molecular weight liquid crystal material and an electrolyte is preferably used. As the liquid crystalline polymer constituting the mixed film, various main chain type or side chain type liquid crystalline polymers can be used, and particularly, the main chain of the polymer is composed of a spacer part and a mesogenic group. A side chain type grafted with a side chain liquid crystalline group is preferably used.

The chemical structure of the main chain constituting the side chain type liquid crystalline polymer may be arbitrary, but it is preferable that the main chain includes a structure having flexibility to some extent, and such an example is not limited to this. For example, polyoxetane chain, polysiloxane chain, polymethacrylate chain, polyacrylate chain,
Examples thereof include polyoxyethylene chains, polychloroacrylate chains, polyester chains and the like.

Examples of the spacer constituting the side chain liquid crystalline group of the side chain type liquid crystalline polymer include alkylene chains (methylene chains etc.), oxyalkylene chains, siloxane chains, ester chains, ether chains, oxetane chains and butadiene. Examples of the mesogen group include various conventionally known mesogen groups corresponding to the chemical structure of the core of a normal liquid crystal material. The graft ratio of the side chain liquid crystalline group is arbitrarily set.

Since the conditions such as the structure of the liquid crystalline polymer, the average molecular weight and the molecular weight distribution have a great influence on the characteristics of the device, these conditions should be appropriately set in accordance with the required properties of the device. Good. For example, the liquid crystalline polymer may have a crosslinked structure. The cross-linked liquid crystalline polymer enhances the self-holding property of the entire system and rapidly transmits the disorder of the liquid crystal alignment caused by the movement and collision of the electrolyte when a DC or low-frequency electric field is applied. Improve the responsiveness of. The cross-linking of the liquid crystalline polymer may be carried out directly between the main chains or via a suitable cross-linking agent. In the case of a side chain type liquid crystalline polymer, the main chains may be crosslinked with each other via a side chain liquid crystalline group. The bond structure for crosslinking may be any chemical bond (covalent bond, ionic bond, hydrogen bond, coordinate bond, etc.).

The liquid crystalline polymer has, for example, a molecular weight of 10
It may be an oligomer of about 000 or less. These liquid crystalline polymers may be used alone or in combination of two or more. Low molecular weight (“low molecular weight” here means that it does not have the main chain structure and side chain structure like liquid crystalline polymer, and is not defined by molecular weight at all) As a material, various liquid crystal materials that are commercially available or publicly known, and are composed of a single component or a plurality of components, excluding main chain type or side chain type liquid crystalline polymers (for example, nematic liquid crystal, smectic liquid crystal, chiral smectic) are used. LCD etc.) can be used.

As the physical properties of the low-molecular liquid crystal material, those having large dielectric anisotropy Δε and those having large refractive index anisotropy Δn are preferable. Further, as a particularly important factor, when mixed with a liquid crystalline polymer, it exhibits a smectic property or a nematic property in the operating temperature range of the device. The mixed film that exhibits smectic properties in the operating temperature range of the device has the above-mentioned memory property. On the other hand, the mixed film that exhibits nematic properties in the operating temperature range of the device has the fail-safe function as described above.

These liquid crystal materials may be used alone or in combination of two or more. The compounding ratio of the low-molecular liquid crystal material is not particularly limited, but the ratio of the low-molecular liquid crystal material in the whole liquid crystal is preferably in the range of 40 to 95% by weight, and in the range of 60 to 90% by weight. More preferably. If the proportion of the low-molecular liquid crystal material is less than the above range, the response speed of the device may be slowed. Conversely, if the proportion of the low-molecular liquid crystal material exceeds the above range, the main chain is bombarded with ions. The probability is getting smaller,
Conversion from transparent to cloudy may be difficult to occur, and the self-supporting property of the mixed film may be insufficient, so that a flexible large-area liquid crystal element may not be configured.

Any electrolyte can be used as long as it is soluble in the liquid crystal material. For example, the general formula (1):

[0025]

[Chemical 1]

(Where R¹, R², R³, R^FourAre the same or
Are different from straight-chain or branched C1-C6 al
Represents a kill group, and Yo is F, Cl, Br, I, ClO_Four, P
F_Four, BF _FourEtc. ) Quaternary ammonium represented by
Salts are preferred. The amount of electrolyte added is
About 0.05 to 1% by weight is preferable with respect to the total amount of the mixed film.
Yes. Even if one type of electrolyte is used alone, two types of such electrolytes are used.
You may use together the above.

Various known dichroic dyes can be added to the mixed film composed of the above components in order to color the display. Further, the mixed film may be mixed with various additives, a non-liquid crystal compound, or the like within a range that does not impair the property, to adjust the property. The structure of the present invention can be applied to the manufacture of devices using various liquid crystal materials other than the above mixed film.

According to the liquid crystal element having the above-mentioned structure, the pair of film base materials 2 are adhered and fixed to each other via the thin adhesive layer 4 in a relatively large area provided outside the periphery of the liquid crystal layer 3. Then, since the liquid crystal layer 3 is sealed, the durability of the sealed portion can be improved without impairing the flexibility of the element. Therefore, the liquid crystal element of the present invention does not deteriorate in performance due to air bubbles penetrating into the element even after long-term use, and thus it is possible to dramatically improve the durability of the flexible liquid crystal element. Become.

Next, the manufacturing method of the present invention will be described. In the manufacturing method of the present invention, first, as shown in FIGS. 1 (a) and 2 (a), the inside of the liquid crystal layer forming region 2a on the surface of one film substrate 2 on which the electrode layer 21 is formed. In addition, the spacer 1 is adhered and fixed by the adhesive resin 40, and a region (hereinafter, referred to as a “sealing region”) of the film base material 2 on the outside of the periphery of the liquid crystal layer forming region 2a.
The adhesive layer 4 is formed on 2b.

Next, a liquid crystal material 30 which is a raw material of the liquid crystal layer 3 is sandwiched between the film base material 2 and the other film base material 2, and the liquid crystal material 30 is sandwiched between the film base material 2 and the other film base material 2 as shown in FIGS. ) As shown by the black arrow in the drawing, a lamination process is performed by passing it between a pair of laminating rolls R and the like. Then, in the liquid crystal layer forming region 2a, the pair of film base materials 2 is held at a predetermined interval by the spacers 1 which are bonded and fixed, and the liquid crystal material 30 is filled therein to form the liquid crystal layer 3. It In the sealing area 2b outside the liquid crystal layer forming area 2a, the liquid crystal material 30 is extruded by the laminating roll R, and the pair of film base materials 2 are directly bonded via the adhesive layer 4. Then, as shown in FIGS. 1 (c) and 2 (c), the liquid crystal layer 3 is formed in the liquid crystal layer forming region 2a, and the film base materials 2 in the sealing region 2b outside the periphery of the liquid crystal layer 3 are formed. Then, the liquid crystal element of the present invention in which the liquid crystal layer 3 is sealed by being directly bonded with the adhesive layer 4 is completed.

Among the above-mentioned manufacturing methods, as a method for adhering and fixing the spacer 1 on the surface of the film base material 2, for example, a predetermined amount of the spacer 1 is dispersed and applied in a solution in which an adhesive resin 40 is dissolved. A method in which a liquid is prepared, the coating liquid is applied to the surface of the film substrate 2 and then the solvent is evaporated and removed is suitably adopted. In order to bond and fix the spacer 1 only in the liquid crystal layer forming region 2a, the above coating solution is applied to the entire surface of the film substrate 2 by a coating method such as a spin coating method or a bar coating method, and dried to form a film. A method of removing the spacers 1 in the sealing region 2b after adhering and fixing the spacers 1 to the entire surface of the base material 2, in a state where the sealing region 2b is masked with a mask material,
The liquid crystal layer forming region 2 is formed by applying a coating liquid on the surface of the film base material 2 and drying it, and then using a method of removing the mask material, a screen printing method, or the like.
Examples thereof include a method of applying the coating liquid only in a.

When any of the above methods is adopted, it is desirable to remove only the spacer 1 so that the layer of the resin 40 remains in the sealing region 2b. Since the resin 40 is adhesive as described above, there is an advantage that it can be used as it is as the adhesive layer 4 for adhering the film base materials 2 to each other. On the other hand, when the methods (1) and (2) are adopted, it is necessary to newly form the adhesive layer 4 in the sealing region 2b. As a method of forming the adhesive layer 4 in the sealing region 2b,
Similarly to the above, in the state where the liquid crystal layer forming area 2a is masked with a mask material, a method of applying a coating liquid for an adhesive layer on the surface of the film base material 2 and drying it, and then removing the mask material, screen printing A method of applying the coating liquid for the adhesive layer only to the sealing region 2b using a method or the like can be used.

The resin 40 for adhering and fixing the spacer 1 in the liquid crystal layer forming region 2a and the resin constituting the adhesive layer 4 formed in the sealing region 2b are selected from various conventionally known resins. Various resins having excellent optical characteristics and adhesiveness can be used. Spacer 1
The resin 40 for adhering and fixing the adhesive layer 4 and the resin forming the adhesive layer 4 may be the same or different.
As such a resin, a thermoplastic resin such as an acrylic resin can be used, and a curable resin that is cured by heat, light, a curing agent (crosslinking agent, etc.) such as an epoxy resin or a curable acrylic resin is used. You can also The curable resin is added to the coating liquid in the state of prepolymer, oligomer, etc. before the curing reaction. When the curable resin is used for bonding and fixing the spacer 1, the spacer 1 can be more firmly fixed to the surface of the film base material 2. Since the curable resin loses its adhesiveness after the curing reaction, when it is used for the adhesive layer 4, if a pair of film base materials 2 are bonded by a laminating process or the like, then the curing reaction may be performed by heat or light. Good.

In the manufacturing method shown in the drawing, the spacers 1 are adhered and fixed to the surface of the same film base material 2 and the adhesive layer 4 is formed, but the spacers 1 are formed on the surface of one film base material 2. It may be adhered and fixed, and the adhesive layer 4 may be formed on the surface of the other film substrate 2. In addition, the spacers 1 may be bonded and fixed to the surfaces of both film base materials 2, or the adhesive layer 4 may be formed on the surfaces of both film base materials 2.

[0035]

The present invention will be described below with reference to examples.
The configuration of the present invention is not limited to the examples below. Example 1 1 % by weight of a spacer (made of benzoguanamine resin, spherical, particle size 10 μm) in a dichloromethane solution (resin concentration: 0.2% by weight) of an acrylic thermoplastic resin (made by Teikoku Chemical Co., Ltd.)
After mixing and shaking well, ultrasonic vibration was applied to uniformly disperse the spacers to prepare a coating liquid.

Immediately after the dispersion, the coating solution was immediately applied to the surface of the film substrate (PES-ITO film) on the side where the ITO film was formed by spin coating (coating conditions:
(2500 rpm, 120 seconds), and then dried at 100 ° C. for 1 hour, and the spacer was adhered and fixed by a resin in a state where the spacer was uniformly dispersed on the entire surface of the film substrate. Next, the spacer adhered and fixed to the sealing region 2b of the film base material is selectively removed using an adhesive tape,
As shown in FIGS. 1 (a) and 2 (a), the film substrate 2
The spacer 1 was left only in the liquid crystal layer forming region 2a on the surface of the. In addition, at this time, in the sealing region 2b where the spacer 1 was selectively removed, the resin layer to which the spacer 1 was adhered and fixed was left as the adhesive layer 4 for adhering the pair of film base materials 2.

Next, as shown in FIG. 2 (b), a paste-like liquid crystal material 30 obtained by the following manufacturing method is placed on the surface of the film base material 2 on which the spacers 1 are fixed, and from above By laminating one film base material (PES-ITO film) 2 so that the ITO film is in contact with the liquid crystal material, and laminating it with a pair of laminating rolls R, and adhering it, the layer structure shown in FIG. 1 (c) is obtained. A liquid crystal element having the above was manufactured. <Manufacture of liquid crystal material> The following formula (2):

[0038]

[Chemical 2]

A side chain type liquid crystalline polymer having a repeating unit represented by (PLC, weight average molecular weight M _w = 1000)
0) and a low-molecular liquid crystal material (Smectic mixed liquid crystal manufactured by Merck Japan Ltd.) are mixed in a weight ratio of 1: 4, and an electrolyte of 0.05% by weight based on the total amount of both liquid crystal materials. (Tetraethylammonium bromide) was mixed, stirred and mixed to produce a paste-like liquid crystal material.

Comparative Example 1 After laminating was performed in the same manner as in Example 1 except that the spacers in the region outside the liquid crystal layer forming region were not removed, the peripheral portion of the element was sealed with an adhesive tape. Then, a liquid crystal element was produced. When the elements of the observation examples and comparative examples were visually observed, it was found that air bubbles were mixed in from the peripheral portion of the element of the comparative example. On the other hand, it was confirmed that air bubbles were not mixed in the device of the example and that the device had a uniform liquid crystal layer.

Further, when the elements of the above-mentioned Examples and Comparative Examples were bent with the opposite sides of the elements by hand and then the elements were observed again, air invaded the gaps of the adhesive tape in the Comparative Examples. Although the amount of bubbles in the peripheral portion of the device was increased, it was confirmed that the devices of the examples did not show inclusion of bubbles and still maintained a uniform liquid crystal layer.

[0042]

As described above in detail, in the liquid crystal device of the present invention, a pair of film base materials are adhered and fixed to each other in a relatively large area provided outside the periphery of the liquid crystal layer. Since it is sealed, the durability of the sealed portion is high. Further, in the sealing region, since the pair of film base materials are adhered and fixed to each other via the thin adhesive layer, there is no fear that the flexibility of the element is impaired. Therefore, the liquid crystal device of the present invention is excellent in durability, even though it is flexible, without causing bubbles to enter the device and deteriorating the performance even after long-term use.

According to the method of manufacturing a liquid crystal element of the present invention, the liquid crystal layer is sealed at the same time as the laminating process.
The liquid crystal device of the present invention can be manufactured without causing air bubbles to enter the device during manufacturing, and the manufacturing yield of products is improved.

[Brief description of drawings]

FIG. 1A to FIG. 1C show steps of the production method of the present invention,
It is sectional drawing which shows the layer structure of an example of the liquid crystal element of this invention manufactured by it.

FIG. 2A to FIG. 2C are perspective views of the above manufacturing process.

FIG. 3 is a cross-sectional view showing a conventional liquid crystal element sealing structure.

[Explanation of symbols]

 1 Spacer 2 Film Base Material 2a Liquid Crystal Layer Forming Area 2b Sealing Area 21 Electrode Layer 3 Liquid Crystal Layer 30 Liquid Crystal Material 4 Adhesive Layer

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toru Kashiwagi 1-3-3 Shimaya, Konohana-ku, Osaka City Sumitomo Electric Industries, Ltd. Osaka Works

Claims (2)

[Claims] 1. A liquid crystal device having a structure in which a liquid crystal material is filled between a pair of film base materials having electrode layers formed on at least one surface thereof, which are held at predetermined intervals by spacers, to form a liquid crystal layer. In, the edge of the liquid crystal layer is arranged inward from the edge of the film base material, and a pair of film base materials are provided outside the periphery of the liquid crystal layer, without a liquid crystal layer and a spacer, and a thin adhesive layer. A liquid crystal element, in which a region bonded and fixed by is provided and the liquid crystal layer is sealed. 2. A manufacturing method for manufacturing the liquid crystal device according to claim 1, wherein a spacer is bonded and fixed in a liquid crystal layer forming region of at least one surface of the pair of film base materials, After forming an adhesive layer on at least one of the film base material and the other film base material in the area outside the liquid crystal layer forming area, the liquid crystal material may be sandwiched between the film base materials and laminated. A method for manufacturing a characteristic liquid crystal element.