JPH01312527A - Liquid crystal device and its production - Google Patents

Abstract

PURPOSE:To obtain a memory effect by adopting a synthetic resin obtd. by copolymerizing a specified polymerizable compsn. for a transparent solid material dispersed in a nematic liquid crystal material. CONSTITUTION:The synthetic resin obtd. by copolymerizing the polymerizable compsn. consisting of bifunctional acrylic monomers or oligomers and N-vinyl-2- pyrrolidone is adopted for the transparent solid material dispersed in the nematic liquid crystal material. The transparent solid material interposed in the continuous phase of the liquid crystal material may have flexibility, resilience and elasticity as the solid properties thereof. The particles thereof having suitable sizes and shapes according to the wavelengths of light are selected in case of the particulate material. The memory effect is obtd. in this way and the continuous display of the same display even after the voltage is removed is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal device comprising a liquid crystal-containing thin film that can enlarge the display surface, and a method for manufacturing the same. It is capable of controlling the transmission of illumination light electrically, and has the characteristic of maintaining a transparent state even after the voltage is removed (hereinafter referred to as the "memory effect"), so it can display characters and figures. billboards, information boards, etc. that need to be displayed for a certain period of time.
Used as display devices such as decorative display boards.

[Conventional technology]

Conventionally, liquid crystal display elements are TN, which uses nematic liquid crystal.
type and STN type have been put into practical use.

In addition, devices using ferroelectric liquid crystals have also been proposed. These liquid crystal display elements require polarizing plates,
It also requires orientation treatment.

On the other hand, as a method for producing a large, inexpensive liquid crystal device that is bright and has good contrast without requiring them, published patent publication No. 58-501631 discloses gelatin,
A method is described in which a liquid crystal is encapsulated with an encapsulating material such as avia rubber or polyvinyl alcohol, and a polymer in which the encapsulated liquid crystal is dispersed is formed into a film.

In the technology disclosed in the above specification, if the liquid crystal molecules encapsulated with polyvinyl alcohol have positive dielectric constant anisotropy in a thin layer, the liquid crystal molecules can be encapsulated in the presence of an electric field. aligned in the direction of the electric field, the refractive index n of the liquid crystal
When 0 and the refractive index n of the polymer are equal, an induced state occurs. When the electric field is removed, the liquid crystal molecules return to their random alignment, and the refractive index of the liquid crystal droplet deviates from no, so the liquid crystal droplet scatters light at its interface and blocks light transmission, so the thin layer body It becomes cloudy.

Techniques for forming thin films from polymers containing dispersed encapsulated liquid crystals are also known in addition to those mentioned above. Thing, Japanese Patent Publication No. 62-2231
The patent describes a dispersion of liquid crystals in a special UV-curable polymer.

[Problem to be solved by the invention]

However, liquid crystal devices in which these encapsulated liquid crystals are dispersed and made into a thin film of nine polymers have a memory effect because the transparent state obtained in the presence of voltage returns to the original cloudy state when the voltage is removed. do not. If we can provide a liquid crystal device with a memory effect, we can expect the applications of liquid crystal devices to further expand.

The problem to be solved by the present invention is to provide a liquid crystal device having a memory effect and a method for manufacturing the same.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a first tie and a second tie liquid crystal device described below.

That is, the first type of liquid crystal device of the present invention has two substrates each having an electrode layer and at least one of which is transparent, and a light control layer supported between the substrates, wherein the light control layer is a nematic layer. A liquid crystal device consisting of a liquid crystal material and a transparent solid material, wherein the nematic liquid crystal material forms a continuous phase and the transparent solid material is dispersed within the nematic liquid crystal material.

A liquid crystal device in which the transparent solid substance is a synthetic resin obtained by copolymerizing a polymerizable composition consisting of (1) a bifunctional acrylate monomer or oligomer and (b) N-vinyl-2-pyrrolidone, A second type of liquid crystal device comprises two substrates having electrode layers and transparent on at least three sides, and a skin light control layer supported between the substrates, the light control layer comprising a nematic liquid crystal material and a transparent transparent layer. In a liquid crystal device consisting of a solid substance, wherein the nematic liquid crystal material forms a continuous phase and the transparent solid substance is dispersed in the nematic liquid crystal material, (1) the nematic liquid crystal material contains 5 to 5 to (2) The transparent solid substance is represented by the general formula <1) (wherein R represents a hydrogen atom or a methyl group, and n represents an integer from 1 to 9). It is a liquid crystal device that is a synthetic resin obtained by polymerizing monomers.

These liquid crystal devices can be preferably manufactured as follows.

Namely, the method for manufacturing the first type of liquid crystal device is as follows:
Between two substrates, at least one of which is transparent, having an electrode layer, as essential components: (1) a nematic liquid crystal material;

(2) A polymerizable composition comprising (a) a difunctional acrylate monomer or oligomer and (b) N-vinyl-2-pyrrolidone, (3) a photopolymerization initiator, and optionally a chain transfer agent and a photointensifier. The nematic liquid crystal material forms a continuous phase by irradiating ultraviolet rays through the transparent substrate with a solution consisting of a sensitizer, a dye crosslinking agent, etc., thereby copolymerizing the polymerizable composition, thereby forming a continuous phase of the nematic liquid crystal material and making it transparent. A method of manufacturing a liquid crystal device in which a light control layer in which a solid substance is dispersed in a nematic liquid crystal material is supported between substrates is mentioned.

In addition, as a method for manufacturing the second type of liquid crystal device,
(1)) as an essential component between two substrates having an electrode layer, at least one of which is transparent. a nematic liquid crystal material containing 5 to 50% by weight of a carbon-based liquid crystal compound, (2) a monomer represented by general formula (1), (3) a photopolymerization initiator, and optionally a chain transfer agent and photosensitizer. The nematic liquid crystal material forms a continuous phase by irradiating ultraviolet rays through the transparent substrate with a solution consisting of a crosslinking agent, a dye crosslinking agent, etc., thereby polymerizing the monoi- Mention may be made of methods of manufacturing liquid crystal devices in which a light control layer in which a solid substance is dispersed in a nematic liquid crystal material is supported between substrates.

In these devices, the substrate may be a rigid material such as glass or metal, or a flexible material such as a glass film. The two substrates can be placed facing each other with an appropriate distance between them.

Furthermore, at least one of the substrates must be transparent so that the light control layer supported between the two substrates can be seen from the outside. However, complete transparency is not required. When the liquid crystal device of the present invention is used to act on light passing from one side of the device to the other, both substrates need to be transparent. Appropriate transparent or opaque electrodes, depending on the purpose, are arranged entirely or partially on this substrate.

A nematic liquid crystal material and a transparent solid component are interposed between the two substrates. It is preferable that a sweep for maintaining the distance be interposed between the two substrates in a conventional manner, similar to well-known liquid crystal devices.

Examples of nematic liquid crystal materials include 4-substituted benzoic acid 4'-substituted phenyl ester, 4-substituted cyclohexane/
Cardoic acid 4'-substituted phenyl ester, 4-[substituted cyclohexanecarmenic acid 4'-substituted biphenyl ester,
4-(4-Substituted cyclohexanecarmenyl)benzoic acid 4'-substituted phenyl ester, 4-(4-R-substituted cyclohexyl)benzoic acid 4'-substituted phenyl ester, 4
-(4-substituted cyclohexyl)benzoic acid 4'-substituted cyclohexyl ester, 4-substituted biphenyl,
4-substituted phenyl-4'-substituted cyclohexane, 4-substituted 4"-substituted terphenyl, 4-substituted biphenyl 4'-
a-substituted cyclohexane, z-c4'-im phenyl)-5
Nematic liquid crystals such as -substituted pyrimidyl y, which are usually used for display lids of watches, calculators, etc., can be used.

When using a polymerizable composition consisting of a monomer represented by general formula (1), 5 to 50% of a tolan liquid crystal compound is used.
A nematic liquid crystal material containing i% by weight is used.

Examples of nematic liquid crystal materials containing tolan-based liquid crystal compounds include r DOX manufactured by Dainippon Ink and Chemicals.
-4067J etc. can be mentioned.

Nematic liquid crystal materials require the formation of a continuous phase between two substrates. If the ratio of liquid crystal material components is low, it is difficult to form a continuous phase. The proportion of the liquid crystal material in the light control layer components is preferably 60% by weight or more, and preferably 60 to 90% by weight in the light control layer.

The transparent solid substance interposed in the continuous phase of this liquid crystal material is
It may be dispersed in the form of particles, but preferably has a three-dimensional network structure. In any case, it is essential to form an optical interface with the liquid crystal material and to cause light scattering to occur. Its transparency can be appropriately determined depending on the purpose of use of the device, and its solidity is not limited to solidity, but can be flexible, pliable, and elastic depending on the purpose. It's okay. If the particles are in the form of particles, they are too large compared to the wavelength of the light, and if they are too small, no light scattering properties can be expected, but particles of an appropriate size and shape can be selected depending on the purpose.

Synthetic resins are suitable as these transparent solid substances. Ultraviolet curable monomers or oligomers are preferred as those that provide a three-dimensional network structure.

Examples of difunctional acrylate monomers or oligomers used in the present invention include 1,6-hexanediol noacrylate, diethylene glyco-/+7 diacrylate, neointyl glycol diacrylate, polyethylene glycol diacrylate, and ethylene oxide bisphenol A diacrylate. Examples include acrylate, diacrylated isocyanurate, cabrocton-modified neointylhydroxypivalate diacrylate, and the like.

The proportion of N-vinyl-2-pyrrolidone used is preferably in the range of 10 to 50% by weight of the polymerizable composition.

In the monomer represented by the general formula (R), those in which R represents a hydrogen atom or a methyl group, and n represents an integer of 1 to 9 are preferred, and those in which n represents 3 or 4 are particularly preferred.

Examples of photopolymerization initiators that can be used in the present invention are shown below.
The photopolymerization initiators are not limited to these.

The amount of photopolymerization initiator used is preferably in the range of 0.5 to 10 parts by weight, particularly preferably in the range of 1 to 3 parts by weight, based on 100 parts by weight of the light control layer component.

Optional components include chain transfer agents, photosensitizers, dyes, crosslinking agents, etc., and can be appropriately selected depending on the type of monomer, oligo9mer, etc., and the performance of the desired liquid crystal device.

In particular, the combined use of a chain transfer agent can be extremely effective depending on the type of monomer or oligomer, preventing the resin from becoming too cross-linked, thereby making the liquid crystal material more responsive to electric fields, and reducing the Demonstrates voltage drive performance. Good examples of chain transfer agents are butanedioldithioglopionate, -entaerythritolteto2kis (β-thiopropionate), triethylene glycol dimercagutan, and the like. The amount of chain transfer agent added varies depending on the type of monomer or oligomer used, but if it is too small, the effect will be weak, and if it is too large, the opacity of the device will decrease and the contrast of the display will deteriorate. The effective amount is believed to be 0.05-30%, based on monomer or oligomer, with 0.1-20% being preferred.

To support a solution containing each of these components between two substrates, this solution may be injected between the substrates, but it may be applied onto one substrate using a coater such as a spinner. , and then the other substrate may be overlapped.

Curing of an uncured solution can be accomplished by irradiating a suitable dose of ultraviolet light through the transparent substrate. Depending on the type of monomer or oligomer or optional components, heat or electron beam may be used instead.

A liquid crystal device configured in this manner has a memory effect not found in conventional liquid crystal devices.

〔Example〕

EXAMPLES The present invention will be described below in more detail with reference to Examples, but the present invention is not limited to these Examples. In addition, "parts" in the examples are "parts by weight"
represents.

Example 1 "DOX-4067J 74 parts (nematic liquid crystal material manufactured by Dainippon Ink &Chemicals)" Polyethylene glycol 200 diacrylate 24 parts "Daroki A 1173J 2 parts (photopolymerization initiator manufactured by Merck Co., Ltd.) The above compositions were mixed. The obtained mixture was inserted between two conductive glass plates of 10 cIIL square so that the average film thickness was 15 μm, and the monomer was cured (polymerized) by irradiation with ultraviolet rays.The curing conditions were as follows: 3.5m below the metal halide lamp (80W/cm)
UV light was irradiated. The applied energy corresponds to 500 mJΔ.

The obtained liquid crystal device was in an opaque state, and changed to a transparent state by applying a driving voltage of 30V. This liquid crystal device maintains its transparent state even after the voltage is removed, and as shown in Figure 1, it remains transparent even after 3 days! I was maintaining I.

Example 2 A liquid crystal device was manufactured in the same manner as in Example 1 except that triethylene glycol diacrylate was used instead of 5 polyethylene glycol 200 diacrylate.

The obtained liquid crystal device had a memory effect.

Example 3 "DOX-4062J 78 parts (nematic liquid crystal material manufactured by Dainippon Ink & Chemicals @) 1.6-hexanediol diacrylate 5.6 parts N-vinyl-2
-Pyrrolidone 5.6 parts 1'7o=? ,7 117
3 J O, 5 parts A liquid crystal device was entirely manufactured in the same manner as in Example 1 except that the above composition was used.

The obtained liquid crystal device is in an opaque state,
50 parts m) It changed to a transparent state by applying a voltage of 40 Vi. This liquid crystal display remained transparent for about one day even after the voltage was removed.

Examples 4 to 6 and Comparative Example 1 The compositions shown in Table 1 were mixed, and various liquid crystal devices and interior chairs were manufactured using the same machine as in Example 1. It is shown in Table 1.

[Effects of the Invention] The liquid crystal device of the present invention does not require a polarizing plate, is easy to manufacture, and is easy to increase in size.

Furthermore, the liquid crystal device of the present invention has a Mesoli effect,
It is economical because the same display can be displayed continuously for 10 minutes to several days even after the voltage is removed.

[Brief explanation of the drawing]

FIG. 1 is a chart showing the light transmission characteristics of the liquid crystal device obtained in Example 1 of the present invention. Curve 1 shows the light transmission characteristics in the initial opaque state, and curve 2 shows the light transmission curve in the transparent state measured 3 days after applying a voltage to make it transparent, and then removing the voltage. This is what is shown. Agent: Patent Attorney Katsutoshi Takahashi Figure 1 Wavelength (nm)

Claims (1)

[Claims] 1. Two substrates each having an electrode layer and at least one of which is transparent, and a light control layer supported between the substrates, the light control layer comprising a nematic liquid crystal material and a transparent material. Consisting of a solid substance,
In a liquid crystal device in which the nematic liquid crystal material forms a continuous phase and the transparent solid substance is dispersed in the nematic liquid crystal material, the transparent solid substance comprises (a) a difunctional acrylate monomer or oligomer and ( b) A liquid crystal device characterized in that it is a synthetic resin obtained by copolymerizing a polymerizable composition comprising N-vinyl-2-pyrrolidone. 2. The liquid crystal device according to claim 1, wherein the ratio of the nematic liquid crystal material to the polymerizable composition is in the range of 60:40 to 90:10 by weight. 3. Claim 1, wherein the proportion of (b) N-vinyl-2-pyrrolidone used in the polymerizable composition is in the range of 10 to 50% by weight.
The liquid crystal device described. 4. Two substrates having electrode layers, at least one of which is transparent, and a light control layer supported between the substrates, the light control layer comprising a nematic liquid crystal material and a transparent solid substance,
In a liquid crystal device in which the nematic liquid crystal material forms a continuous phase and the transparent solid substance is dispersed in the nematic liquid crystal material, (1) the nematic liquid crystal material contains a tolan-based liquid crystal compound from 5 to 50%;
(2) The transparent solid substance has the general formula (I) ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R represents a hydrogen atom or a methyl group, and n is 1 ~
Represents the integer 9. ) A liquid crystal device characterized in that it is a synthetic resin obtained by polymerizing a monomer represented by: 5. The weight ratio of the nematic liquid crystal material and the monomer represented by general formula (I) is 60:40 to 90:10.
5. The liquid crystal device according to claim 4, which is within the range of . 6. Between two basic sheets, at least one of which is transparent, having an electrode layer, (1) a manetic liquid crystal material, (2) (a) a difunctional acrylate monomer or oligomer, and (b) N-vinyl-2-pyrrolidone. A nematic liquid crystal material is made into a continuous phase by copolymerizing the polymerizable composition by irradiating ultraviolet rays through a transparent substrate with a solution consisting of (3) a photopolymerization initiator and (3) a photopolymerization initiator. and a light control layer having a transparent solid material dispersed in a nematic liquid crystal material supported between substrates. 7. The method for manufacturing a liquid crystal device according to claim 6, wherein the ratio of the nematic liquid crystal material to the polymerizable composition is in the range of 60:40 to 90:10 by weight. 8. The method for manufacturing a liquid crystal device according to claim 6, wherein the proportion of (2)(b) N-vinyl-2-pyrrolidone used in the polymerizable composition is in the range of 10 to 50% by weight. 9. Between two substrates, at least one of which is transparent, having an electrode layer, (1) a nematic liquid crystal material containing a tolan-based liquid crystal compound in a range of 5 to 50% by weight, (2) general formula (I) ▲mathematical formula , chemical formulas, tables, etc.▼ (In the formula, R represents a hydrogen atom or a methyl group, and n is 1 to
Represents the integer 9. The nematic liquid crystal material forms a continuous phase by irradiating ultraviolet rays through a transparent substrate with a solution consisting of a monomer represented by ) and (3) a photopolymerization initiator, thereby polymerizing the monomer (2). and a method of manufacturing a liquid crystal device in which a light control layer in which a transparent solid material is dispersed in a nematic liquid crystal material is supported between substrates. 10. The weight ratio of the nematic liquid crystal material and the monomer represented by general formula (I) is 60:40 to 90:1
10. The method for manufacturing a liquid crystal device according to claim 9, wherein the liquid crystal device is in the range of 0.