JPH04188105A - Manufacture of liquid crystal device - Google Patents

Abstract

PURPOSE:To improve resistant value of a dimming layer and obtain a liquid crystal device having little flicker of image plane and high contrast by using ultraviolet rays intercepting short wave ultraviolet territory for manufacture. CONSTITUTION:As ultraviolet rays to polymerize a photopolymerizing composite and form transparent high polymer substance of three dimensional network in a continuous phase of liquid crystal, the ultraviolet rays intercepting short wave ultraviolet territory are used. Ultraviolet rays in short wave territory cause photo-deterioration of liquid crystal material or photo-reaction, lowers resistant value of a liquid crystal device, and hence these are intercepted by the use of an ultraviolet cut filter and the like to perform ultraviolet ray hardening. Hereby, a fall of the resistant value of a liquid crystal material is restrained and a liquid crystal device having low drive voltage, excellent steepness, and high contrast can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a liquid crystal device that can be manufactured in a large area. It is a device that can electrically or thermally control blocking and transmitting information, and is used for view blocking screens in building windows and show windows, as well as for lighting control curtains. The present invention relates to a method of manufacturing a liquid crystal device that is used as a high information display such as a display of office automation equipment, an advertising board, a guide board, a decorative front board, etc. by electrically switching the display with responsiveness.

[Prior Art] A light control layer supported between two transparent substrates which may have an electrode layer, wherein the liquid crystal material forms a continuous phase and the transparent solid material covers the liquid crystal. In a method for manufacturing a liquid crystal device that exists in a three-dimensional network in a continuous phase of a material (hereinafter referred to as a liquid crystal device), a preparation consisting of a liquid crystal material, a photopolymerizable composition, a photopolymerization initiator, and other optional components is used. When irradiating the light layer constituent material with ultraviolet rays, a method has been used in which the light control layer constituent material is directly irradiated with ultraviolet rays.

[Problems to be Solved by the Invention] The liquid crystal device produced in this way has excellent low voltage drive performance, high contrast, time division drive performance, bright image quality, etc., but the resistance of the obtained liquid crystal device is However, there were problems such as increased power consumption, decreased lifespan, and flickering on the display screen due to decreased voltage holding rate.

The problem to be solved by the present invention is to provide a method for manufacturing a liquid crystal device that is excellent in low voltage drivability, high load stability, time division drivability, bright image quality, etc., has large resistance, and has a high voltage holding ratio. be.

[Means for Solving the Problems] The present inventors have discovered that ultraviolet rays during the production of liquid crystal devices cause photodeterioration of liquid crystal materials more than expected, leading to a decrease in the resistance and voltage holding rate of liquid crystal devices. The above problem has been solved.

That is, in order to solve the above problems, the present invention contains a liquid crystal material, a photopolymerizable composition, and a photopolymerization initiator between two transparent substrates, at least one of which may have an electrode layer. After interposing the material constituting the light control layer, ultraviolet rays are irradiated to polymerize the photopolymerizable composition, thereby adding 3% to the liquid crystal continuous phase.
The present invention provides a method for manufacturing a liquid crystal device in which a transparent polymer substance in the form of a dimensional network is formed, which is characterized in that ultraviolet light with a short wavelength ultraviolet region blocked is used as the ultraviolet light.

The substrate used in the present invention may be made of a rigid material, such as glass or metal, or may be made of a flexible material, such as a plastic film. Two substrates can be placed facing each other with an appropriate distance between them. Furthermore, at least one of the two must be transparent so that the light control layer sandwiched between the two can be seen from the outside world. However, complete transparency is not required. If the liquid crystal device is used to act on light passing from one side of the device to the other, both substrates are provided with suitable transparency. Appropriate transparent or opaque electrodes may be disposed on the entire surface or part of the substrate depending on the purpose.

However, in the case of a flexible material such as a plastic film, it can be used in the manufacturing method of the present invention after being fixed to a rigid material such as glass or metal.

A light control layer made of a liquid crystal material and a transparent polymer material is interposed between the two substrates. Note that it is usually desirable to interpose a spacer between the two substrates for maintaining the distance, similarly to well-known liquid crystal devices.

As the spacer, for example, those for various liquid crystal cells such as mylar, alumina, and polymer beads can be used.

In order to obtain uniform spacing between the substrates, it is important that the spacers are evenly distributed on the substrate surface, and for this purpose: (1) Suspend and disperse the spacers in the material constituting the light control layer so that the spacers do not separate or settle. In between, there is a method in which the suspension or dispersion is spread over the entire surface of the substrate, or (2) a method in which spacers are uniformly spread over the substrate or protrusions for spacers are provided on the substrate in advance. An example of a method for spraying the spacers in advance is to suspend the spacers in a low boiling point solvent, apply the suspension onto the substrate, and then dry the solvent. A method of providing a projection for use is also effective.

The liquid crystal material used in the present invention does not necessarily need to be a single liquid crystal compound, but may be a mixture containing two or more types of liquid crystal compounds or substances other than liquid crystal compounds,
Any material that is generally recognized as a liquid crystal material in this technical field may be used, and among these materials, those having positive dielectric anisotropy are preferred. The liquid crystals used are nematic liquid crystal,
Smectic liquid crystals and cholesteric liquid crystals are preferred, and nematic liquid crystals are particularly preferred. In order to improve the performance, chiral compounds such as cholesteric liquid crystal, chiral nematic liquid crystal, chiral smectic liquid crystal, dichroic dye, etc. may be included as appropriate.

The nematic liquid crystal only needs to exhibit positive dielectric anisotropy (Δε), have Δε of 8 or more, and have a birefringence (Δn) of 0.1 or more.

Regarding the difference in refractive index between liquid crystal and polymer, which is a problem in liquid crystal dispersion type liquid crystal devices, in the present invention, since the liquid crystal component is large, it is possible to combine a wide range of liquid crystals and polymers without worrying too much. Become.

The liquid crystal material that can be used in the present invention is a compound composition composed of a compound group represented by the following general formula, and the characteristics of the liquid crystal material, such as the phase transition temperature of isotropic liquid and liquid crystal, melting point, viscosity, Δn , Δε, solubility with the photopolymerizable composition, etc., and can be appropriately selected and blended for use.

, -Q- represents -C=C- or -COO-, X represents CN, R', R'O or NCS, Y represents HSF or C1, R and R' each independently represents an alkyl group having 1 to 6 carbon atoms, m
represents 1 or 2, and n represents 0 or l.

The proportion of liquid crystal material in the light control layer is 60 to 95% by weight.
A range of 70 to 90% by weight is particularly preferred. (Hereinafter, "%" means "wt%.") Examples of the photopolymerizable composition include polymer-forming monomers or oligomers, which create a three-dimensional network structure in the continuous phase of the liquid crystal material by curing. As long as it is formed, it is not limited to a rigid one, and may be flexible, pliable, and elastic as long as it meets the purpose.

Examples of such polymer-forming monomers include styrene, chlorostyrene, α-methylstyrene, divinylbenzene; substituents include methyl, ethyl, propyl, butyl, amyl, 2-ethylhexyl, octyl, nonyl, dodecyl, Hexadecyl, octadecyl, cyclohexyl, benzyl, methoxyethyl, butoxdiethyl, phenoxyethyl, allyl, methallyl, glycidyl, 2-hydroxyethyl, 2-hydroxypropyl, 3
- acrylates, methacrylates or fumarates with groups such as chloro-2-hydroxypropyl, dimethylamino/ethyl, diethylamine ethyl; ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-butylene gellicol, tetramethylene glycol, hexa Poly(
meth)acrylate or poly(meth)acrylate;
Vinyl acetate, vinyl acetate or vinyl benzoate, acrylonitrile, heptyl vinyl ether, limonene, cyclohexene, diallyl phthalate, 2-13- or 4-vinylpyridine, acrylic acid, methacrylic acid, acrylamide, methacrylamide, N-hydroxymethylacrylamide or N-Hydroxyethyl methacrylamide and their a/l/4 etherification lf;) triol or tri(meth)acrylate obtained by adding 3 moles or more of ethylene oxide or propylene oxide to 821 moles of dametylolpro Di(meth)acrylate of diol obtained by adding 2 moles or more of ethylene oxide or propylene oxide to 1 mol of neopentyl glycol; 2-hydrobodiethyl (meth)
1 mole of acrylate and phenyl isocyanate or n-butyl isocyanate* -) 1%! : Reaction product of; poly(meth)acrylate of dipentaerythritol; poly(meth)acrylate of tris-(hydroxyethyl)-isocyanuric acid; poly(meth)acrylate of tris-(hydroxyethyl)-phosphoric acid;
(hydroxyethyl)-dicyclopentadiene mono(meth)acrylate or di(meth)acrylate; pivalic acid ester neopentyl glycol diacrylate;
Examples include caprolactone-modified hydrobovine cypiparic acid ester neopentyl glycol cyacrylate; linear aliphatic diacrylate; polyolefin-modified neopentyl glycol diacrylate.

Examples of polymer-forming oligomers include (1) bisphenol A epoxy resin, (meth)acrylic acid,
Furthermore, in some cases, epoxy (meth)acrylate obtained by esterifying a long chain fatty acid such as coconut oil fatty acid, or a modified long chain fatty acid thereof, or an epoxy (meth)acrylate having a hydroxyl group.
Epoxy (meth)acrylates and modified products thereof, such as epoxy (meth)acrylates having carboxyl groups obtained by adding dibasic acid anhydrides, tetrabasic acid dianhydrides, and trimellitic anhydride to acrylates.

(2) Specification of British Patent No. 1.147.732 (JP-A-51-37193 and JP-A-51-138797)
2 in the molecule obtained by further reacting β-hydroxyalkyl acrylate and/or methacrylate to a terminal incyanate compound obtained by reacting a diisocyanate compound and a polyol in advance as described in An addition polymerizable compound having the above acryloyloxy group and/or methacryloyloxy group.

(3) Dibasic acids such as phthalic anhydride, tetrahydrophthalic anhydride, hydrophthalic anhydride, tetrachlorophthalic anhydride, or head acid anhydride as described in Japanese Patent Publication No. 47-3262 A linear polyester compound having a large number of pendant acryloyloxy groups and/or methacryloyloxy groups obtained by ring-opening polymerization of an anhydride and glycidyl acrylate and/or glycidyl methacrylate.

(4) A polyhydric alcohol having at least three esterifiable hydroxyl groups on adjacent carbon atoms, acrylic acid and/or methacrylic acid, dicarboxylic acid and Polymerizable esters prepared by coesterification with dicarboxylic acids selected from the group consisting of their anhydrides.

(5) British Patent No. 628.150, US Pat.
Formaldehyde, methyl alcohol and β-
A polyacrylic (or polymethacrylic) modified triazine resin obtained by reacting hydroxyalkyl acrylate (or methacrylate), etc.

(6) An unsaturated polyester resin obtained by reacting a glycidyl ether of a polyhydrobutylene compound with acrylic acid or methacrylic acid as described in US Pat. No. 3,377,406.

(7) The general formula described in U.S. Patent No. 3.455.801 and U.S. Patent No. 3.455.802 (wherein R is a divalent saturated or represents an unsaturated aliphatic hydrocarbon group, and R' has 2 carbon atoms.
-1O represents a divalent saturated aliphatic hydrocarbon group, R'' represents a hydrogen atom or a methyl group, and n represents an integer from 1 to 14. A polyester compound having

(8) General formula % described in U.S. Patent No. 3.483.104 and U.S. Patent No. 3.470.079 (wherein A represents 10- or -NH-) At least two groups in one molecule are -NH-, R represents a divalent saturated aliphatic or unsaturated aliphatic hydrocarbon group, and R'' represents a divalent saturated or unsaturated aliphatic hydrocarbon group. Alternatively, it represents a cyclic hydrocarbon, R' represents a hydrogen atom or an alkyl group, and n represents an integer from 1 to 14.) diacrylic modification (or dimethacrylic modification)
Polyamide compound.

(9) The general formula described in 4tr Publication No. 48-37246 (wherein, X represents a hydrogen atom or an acyl group, and R represents a divalent saturated or unsaturated aliphatic or cyclic hydrocarbon group) Representation,
R1 represents a divalent aliphatic hydrocarbon group, R3 represents a hydrogen atom or an alkyl group, A represents 10- or -NH-, and at least two in one molecule are -NH-. , n represents an integer from 1 to 14. ) Diacrylic modified (or dimethacrylic modified) represented by
Polyamide compound.

(10) Saturated or unsaturated dibasic acids or their anhydrides, as described in U.S. Pat. A diacrylic-modified (or dimethacrylic-modified) polyester compound obtained by further reacting a compound having a carboxyl group at the terminal with glycidyl acrylate or glycidyl methacrylate.

(11) General formula -CH, -C-R COOCH, CHCH, 0COC=CH in the molecule as described in Japanese Patent Publication No. 48-12075.

(In the formula, X represents an acyl group or a urethane group, and R is
Represents a hydrogen atom, a chlorine atom, a methyl group, or a cyan group.

) Compounds based on a (meth)acrylic copolymer having an unsaturated acid ester bond in a side chain having a repeating unit represented by the following can be mentioned.

As a photopolymerization initiator, for example, 2.4.6-trimethylbenzoyldiphenylphosphine oxide (BAS
Manufactured by Company F [Lushitun TPOJ), 2-hydroxy-2-
Methyl-1-phenylpropan-1-one (manufactured by Merck & Co., Ltd. [Daro Ushinia 1173J)], 1-hydroxycyclohexylphenyl ketone (manufactured by Ciba Kaigy, “Irgacure 184j”), 1-(4-isopropylphenyl)-
2-Hydroquine-2-methylpropan-1-one (Taroki 71116J, manufactured by Merck & Co.), benzyl dimethyl ketal (Irgacure 6, manufactured by Ciba Geigy)
51J), 2-methyl-1-(4-(methylthio)phenyl]-2-morpholinopropan-1 (Irgacure 907J, manufactured by Ciba Geigy), 2,4-diethylthioxanthone (manufactured by Nippon Kayaku Co., Ltd. [ Kayakia DET
XJ) and ethyl p-dimethylaminobenzoate (Kayacure EPAJ manufactured by Nippon Kayaku Co., Ltd.), isopropylthioxanthone (Kanta Gyu Near Natsute Examples include a mixture with ethyl, but 2,4.6-trimethylbenzoyldiphenylphosphine oxide, which has an absorption range in a longer wavelength range, is particularly preferred because it can block a wide range of short wavelength ultraviolet rays.

The usage ratio of the photopolymerization initiator is 0.1 to 0.1% of the photopolymerizable composition.
A range of 5.0% is preferred.

A chain transfer agent, a photosensitizer, a dye, a crosslinking agent, etc. can be appropriately used in combination with the material constituting the light control layer as an optional component depending on the type of the monomer, oligomer, 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 degree of crosslinking of the resin from becoming too high, 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 butanedioltetrakis (β-thiopropionate), triethylene glycol dimercaptan, 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 tend to deteriorate, so it is preferable. do not have. The effective amount is believed to be 0.05 to 30% by weight of the monomer or oligomer, but 0.05% to 30% by weight of the monomer or oligomer.
A weight ratio of 1 to 20% is suitable.

In the ultraviolet curing method, (1) the curing temperature is set higher than the phase transition temperature between the liquid crystal phase and the isotropic liquid phase of the material constituting the light control layer, and (1) before ffc! By irradiating ultraviolet rays of such intensity that there is no difference in polymerization depending on the thickness of the substrate gap, through an ultraviolet cut filter that blocks the ultraviolet absorption wavelength region of the liquid crystal material in the light control layer constituent material. By equalizing and controlling the mesh size of the three-dimensional network of transparent polymer material formed in the continuous phase of the liquid crystal material sandwiched between the substrates, a clear threshold voltage, A liquid crystal display element having steepness and high resistance value, that is, a liquid crystal device capable of time-division drive display can be manufactured.

When directly irradiated with ultraviolet rays, the ultraviolet rays in the short wavelength region cause photodeterioration or photoreaction of the liquid crystal material more than expected, causing a decrease in the resistance value of the liquid crystal device.

From this point of view, by blocking the ultraviolet absorption region of the liquid crystal material using an ultraviolet cut filter, etc., and performing ultraviolet curing, the decrease in the resistance value of the liquid crystal material is suppressed, and as a result, the driving voltage is low and the sharpness is excellent. , it is possible to manufacture a liquid crystal device with high contrast, that is, a liquid crystal device with excellent time division drive characteristics.

The ultraviolet cut filter used here may be made of a hard material such as glass, or may be made of a flexible material such as a plastic film. Alternatively, a liquid may be sealed in a container or coated on a transparent plate.

Since many liquid crystal materials have an absorption band in the range of 1BOn+n to 360 nm, it is preferable to block ultraviolet rays in this region. However, if the ultraviolet rays in the absorption range of the photopolymerization initiator are blocked, polymerization will not proceed, so taking into account the absorption range of commercially available photopolymerization initiators, an ultraviolet cut filter that blocks ultraviolet rays of 390% m or less is particularly preferable.

Commercially available ultraviolet cut filters include r UV-
35J, rUV-37J, r5L-IAJ, rL-3
Glass filters such as 9J, rL-42J (manufactured by Toshiba Corporation); r LLCI-82J, rSC-39J (
Fuji Photo Film Co., Ltd.) r ZR-350-NEJ
(Manufactured by Sumitomo Cement Co., Ltd.), “Hinis A Film Yo (
(manufactured by Nippon Carnooid Co., Ltd.), r NR2525SMJ
(manufactured by SUNNAED Co., Ltd.) and other film filters.

[Examples] Hereinafter, examples of the present invention will be shown to explain the present invention more specifically. However, the present invention is not limited to these examples.

In the following examples, "%" represents "wt%", and each of the evaluation characteristics means the following symbols and contents.

To: White turbidity; light transmittance (%) TI when applied voltage is 0
Oo: Transparency; light transmittance (%) when the light transmittance hardly increases as the applied voltage increases; V+o: L; threshold; To: 0%; T; . 100%
The applied voltage (Vr+n
s) ■,. : Saturation voltage; Applied voltage (Vrms) at which the light transmittance becomes 90% as above CR: Contrast = TIG. /T0 Also, the illuminance of ultraviolet rays is determined by the UVD- receiver manufactured by Ushio II
Measurement was performed using a Unimeter equipped with a 365PD.

Example 1 80.0% rPN-001J (manufactured by Robic) as a liquid crystal material, and ter KAYAR as a polymerizable oligomer.
AD-HX-620J (Nippon Kayaku Co., Ltd. caprolactone-modified hydroxypivalic acid ester neopentyl glycol cyacrylate) 19.8% and "Lucirin T"
PO, J (BASF Photopolymerization Initiator 2, 4.6-1!
, l methylbenzoyldiphenylphosphine oxide'
) A light control layer constituent material consisting of 0.2% was sandwiched between two ITO electrode glass substrates coated with O, O micron glass fiber spacers, and the entire substrate was heated for 38.
.

While maintaining the temperature at
The liquid crystal device was irradiated for seconds, and a liquid crystal device whose entire surface was uniformly cloudy was obtained.

Physical property transition temperature of rPN-001J 68.5℃ <-25℃ Refractive index n, ・1.7137 n, = 1.533 Δn= 0.254 Threshold voltage (V th) 1.15V Dielectric constant anisotropy Δε=26.9 When the relationship between the applied voltage and the light transmittance of the obtained liquid crystal device was measured, T,=2.4%, T,. . = 88.4%,
CR=36.8, Vro=5.6V r-1V e
o=14.6V r-.

Met.

Moreover, the specific resistance value is 1. It was OX 10”Ω・CI++.

Comparative Example 1 A liquid crystal device was produced in the same manner as in Example 1, except that the light control layer constituent material used in Example 1 was irradiated with ultraviolet light without using the ultraviolet cut filter rL-39J.

When the relationship between the applied voltage and the light transmittance of the obtained liquid crystal device was measured, T = 5.2%, T1°. = 88.3%,
CR=17.0, V+o=9. IV,,,,V
eo=20. IV.

The specific resistance value was 2.0×10′Ω·cm, which was quite low.

Example 2 80.0% rPN-008J (manufactured by Robic) as a liquid crystal material, T rKAYAR as a polymerizable monomer
AD-HX620J and stearyl acrylate 7:3
A mixture of 19.9% and ``Lucirin TPOJ O, 1%
The light control layer constituent material consists of two sheets of ITO1li coated with an 11.0 micron glass fiber spacer.
Glass substrate: While maintaining the entire substrate at 38.3°C, a film ultraviolet cut filter rSC-39J (manufactured by Fuji Photo Film Co., Ltd.) was inserted between the substrate and the ultraviolet irradiation lamp at 25 mW/cm'. The substrate was irradiated with ultraviolet rays for 60 seconds to obtain a liquid crystal device in which the entire surface of the substrate was uniformly cloudy.

r Physical property transition temperature of PN-0083 70.2℃ <-25℃ Refractive index n, = 1.721 n, = 1.512 Δn = 0.209 Threshold voltage (Vth) 1.32V Dielectric constant anisotropy
Δε = 18.0 When the relationship between the applied voltage and the light transmittance of the obtained liquid crystal device was measured, "ro = 4.o%, T1゜. = 90.5%
, CR=22.6, Vlo=3.8V rma,
V. = g, sv,,, and the specific resistance value is
It was 2.5XIO”Ω·cm.

Comparative Example 2 A liquid crystal device was produced in the same manner as in Example 2, except that the light control layer constituent material used in Example 2 was irradiated with ultraviolet light without using the ultraviolet cut filter rSC-39J.

When the relationship between the applied voltage and the light transmittance of the obtained liquid crystal device was measured, T,=4.4%, T,. = 90.6%,
CR=20.8, Vro=4.4V, ,,,,V
-o=9.9V,,, and the specific resistance value is 3.
It was as low as 0x10'Ω·cm.

[Effects of the Invention] According to the method for manufacturing a liquid crystal device of the present invention, it is possible to greatly improve the resistance value of the light control layer during device manufacture, which has been a problem in conventional light-scattering liquid crystal devices.
This makes it possible to provide a high-contrast liquid crystal device that improves voltage holding ratio and eliminates screen flickering.

Therefore, the method for manufacturing a liquid crystal device of the present invention is useful as a method for manufacturing display elements for computer terminals, projection display devices, and the like.

Claims (1)

[Claims] 1. A light control layer constituting material containing a liquid crystal material, a photopolymerizable composition, and a photopolymerization initiator is placed between two substrates, at least one of which is transparent and which may have an electrode layer. In a method for manufacturing a liquid crystal device in which a three-dimensional network-like transparent polymer substance is formed in a liquid crystal continuous phase by irradiating ultraviolet rays and polymerizing the photopolymerizable composition after interposition, short wavelength ultraviolet rays are used as the ultraviolet rays. A method for manufacturing a liquid crystal device characterized by using ultraviolet rays in which a region is blocked. 2. The method for manufacturing a liquid crystal device according to claim 1, characterized in that ultraviolet light whose short wavelength ultraviolet region is blocked using an ultraviolet cut filter is used. 3. The method for manufacturing a liquid crystal device according to claim 1 or 2, characterized in that ultraviolet rays are used in which ultraviolet rays in an absorption region of the liquid crystal material are blocked. 4. The method for manufacturing a liquid crystal device according to claim 1, 2 or 3, characterized in that a photopolymerization initiator having an absorption range other than the UV range to be blocked is used. 5. The method for manufacturing a liquid crystal device according to claim 1, 2, 3 or 4, characterized in that a liquid crystal material exhibiting positive dielectric anisotropy is used. 6. The method for manufacturing a liquid crystal device according to claim 1, 2, 3, 4 or 5, wherein the liquid crystal material accounts for 60% by weight or more of the light control layer constituting material.