JP2001305329A - Method for manufacturing cholesteric liquid crystal color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a cholesteric liquid crystal color filter without necessitating a plurality of light sources or an interference filter, capable of both pattering and fixing of a liquid crystal compound by irradiation with single light, further with no color slippage and with high clearness. SOLUTION: The method for manufacturing the cholesteric liquid crystal color filter is characterized by containing at least one step to imagewisely expose and pattern a cholesteric liquid crystal composition containing at least one king of liquid crystalline polymerizable monomer, at least one king of photoreactive chiral compound and at least one kind of a polymerization initiator with first light and subsequently to photopolymerize and harden it with second light, by keeping the illuminance of the first light in a level not to cause a polymerization reaction of the polymerizable monomer and by keeping the illuminance of the second light in a level to maintain increase of half band widths of selective reflection wavebands of respective patterned pixels to be <=10%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a cholesteric liquid crystal color filter obtained by patterning a cholesteric liquid crystal composition containing a cholesteric liquid crystal compound exhibiting selective reflection and used for a display device such as an LCD.

[0002]

2. Description of the Related Art Color filters used in color liquid crystal displays and the like generally include red (R), green (G),
Each pixel of blue (B) and a black matrix for the purpose of improving display contrast are formed between the pixels. Conventionally, such color filters are mainly those in which pigments are dispersed in a resin or dyes are dyed, and even in a manufacturing method, these colored resin liquids are applied onto a glass substrate by spin coating or the like. A color resist layer is formed by coating, and patterning by photolithography is performed to form a color filter pixel, or a color filter is produced by directly printing a colored pixel on a substrate.

[0003] However, for example, a method of manufacturing a color filter by a printing method has a disadvantage that the resolution of pixels is low and it is difficult to cope with a high-resolution image pattern. Further, there is a disadvantage that coating unevenness when coating on a large-area substrate is large. Further, according to the production method by the electrodeposition method, a color filter having relatively high resolution and little unevenness of the colored layer can be obtained, but has a disadvantage that the production process is complicated and liquid management is difficult. . As described above, as a process for manufacturing a color filter, a manufacturing method capable of easily manufacturing a high-quality color filter with little material loss and high efficiency has been demanded.

[0004] On the other hand, the performance of a color filter is required to be high in transmittance and color purity. In recent years, a method using a dye has optimized the type of dye and the dyeing resin.
In the method using a pigment, the above-mentioned requirement has been improved by using a finely dispersed pigment. However, recently, there is a very high demand for the transmittance and color purity of a color filter in a liquid crystal display (LCD) panel. In particular, in color filters for reflective LCDs, it is difficult to achieve both white display of paper white, contrast, and color reproducibility, while dyes are dyed in a resin or pigments are dispersed in a conventional manufacturing method. Since all of the color filters manufactured are light absorption type color filters, the improvement in color purity by further improving the transmittance has almost reached the limit.

Under such circumstances, a polarization type color filter mainly comprising cholesteric liquid crystal has been known. This polarization-based color filter reflects a certain amount of light and transmits the rest to display an image.
It has high light utilization efficiency and has more excellent performance than light absorption type color filters in terms of transmittance and color purity. on the other hand,
In the production method, from the viewpoint of obtaining a uniform thickness, a method of forming a film on a substrate by a spin coating method or the like has been generally performed. However, there is a problem in that a large material loss occurs, which is disadvantageous in cost. .

A method using a photoreactive chiral compound is useful as a means for ensuring the uniformity of the color purity and the like of the filter film while reducing the number of manufacturing steps while solving the above problems. is there. In this method, when a liquid crystal composition containing a photoreactive chiral compound is irradiated with light having a reaction wavelength of the photoreactive chiral compound in a pattern, the reaction of the chiral compound proceeds according to the intensity of the irradiation energy. The principle is used that the helical pitch of the liquid crystal compound changes for each pixel and the distribution of the selective reflection color is formed individually. That is, there is an advantage that the number of times of patterning at the time of forming the color filter can be completed by one mask exposure. That is, after patterning by irradiating light imagewise, a film functioning as a color filter is formed by fixing the patterned cholesteric liquid crystal compound.

Here, as a means for enabling the above-mentioned immobilization, there has been proposed a method in which a polymer-based liquid crystal compound is used as the liquid crystal compound, and the liquid crystal compound is rapidly cooled to a glass transition temperature or lower after patterning. However, in this method, it was difficult to obtain the heat resistance of the liquid crystal composition after fixing.

As another means, a polymerizable liquid crystal monomer is used as a liquid crystal composition, and after exposure for patterning is performed, the liquid crystal composition itself is further irradiated with light to cause a polymerization reaction in the liquid crystal composition itself to be cured (fixed). )) Has been proposed. However, in this method, although the heat resistance after film formation is excellent, there is a problem that a polymerization reaction partially progresses at a stage of patterning by irradiating light imagewise.

Further, since the sensitive wavelength of the photoreactive chiral compound itself, which changes the pitch of the liquid crystal compound in response to the light exposure during patterning, is substantially in the same wavelength range as the sensitive wavelength of the coexisting polymerization initiator. There is also a problem that the chiral compound reacts again in the process of polymerizing and curing by further light irradiation to cause color shift.

The above two problems are that even if the exposure wavelength is selected using an interference filter or the like, it is difficult to ensure uniformity because the transmission spectrum of the interference filter has an angle dependence. Therefore, conventionally, a method using an electron beam has been proposed for polymerization curing (fixation) after patterning, but it is difficult to say that it is a practical method from an industrial viewpoint.

As described above, both patterning and polymerization curing (fixation) of the liquid crystal composition can be performed by light irradiation, which contributes to simplification of the apparatus, and furthermore, the filter film itself has heat resistance. At present, a production method capable of producing a cholesteric liquid crystal color filter which is highly sharply patterned, has no color shift, and has a uniform hue has not yet been provided.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and achieve the following objects. That is, according to the present invention, while the filter film itself has heat resistance, it is possible to perform both patterning and polymerization curing (fixation) of the liquid crystal composition by light irradiation, and it is highly sharply patterned without color shift. An object of the present invention is to provide a method of manufacturing a cholesteric liquid crystal color filter capable of producing a cholesteric liquid crystal color filter having a uniform hue at low cost. Still another object of the present invention is to provide a method of manufacturing a cholesteric liquid crystal color filter which does not require a plurality of light sources or interference filters and can simplify the device configuration.

[0013]

Means for Solving the Problems The present inventors have conducted intensive studies on a technique for easily producing a cholesteric liquid crystal color filter having high image quality without color shift even in the presence of oxygen. Was obtained. (1) If the irradiation intensity at the time of patterning the liquid crystal compound is made sufficiently small, patterning can be performed with almost no progress of the polymerization reaction occurring in the patterning process. this is,
This is due to radical quenching by oxygen. (2) On the other hand, if the irradiation intensity at the time of polymerizing and curing the liquid crystal compound is higher than a certain value, the liquid crystal molecules are affected by the viscosity of the liquid crystal compound, so that the polymerization reaction occurs before the helical structure changes to a stable pitch. Can be completed. In other words, it cures in an extremely short time, overcoming the effect of radical quenching. (3) However, in the presence of oxygen, the polymerization reaction of the above (2) is liable to be inhibited, and the illuminance needs to be a certain level or more. If the polymerization reaction cannot proceed quickly, color shift occurs.

The means for solving the above problems are as follows. That is, <1> at least one liquid crystal polymerizable monomer;
A cholesteric liquid crystal composition containing at least one photoreactive chiral compound and at least one polymerization initiator is imagewise exposed and patterned by a first light, and then photopolymerized by a second light. Including at least one step of curing, the illuminance of the first light is an illuminance that does not cause a polymerization reaction of the polymerizable monomer, and the illuminance of the second light is a selective reflection of each of the patterned pixels. A method of manufacturing a cholesteric liquid crystal color filter, characterized in that the illuminance is such that the increase in the half-value width of the wavelength band can be maintained at 10% or less.

<2> The method of manufacturing a cholesteric liquid crystal color filter according to <1>, wherein the spectral profiles of the first light and the second light are substantially the same.

<3> The method for manufacturing a cholesteric liquid crystal color filter according to <1> or <2>, wherein the patterning with the first light is performed in the presence of oxygen.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for producing a cholesteric liquid crystal color filter of the present invention, both patterning and fixing (polymerization curing) of a liquid crystal compound are performed by light irradiation using the same type of light source. That is, the liquid crystal compound includes at least one step of imagewise exposing a first light to an image, patterning the same, and further performing photopolymerization and curing by irradiating a second light. Irradiation of the first light at an illuminance that does not cause the polymerization reaction of the above, and irradiation of the second light at an illuminance capable of maintaining an increase in the half-value width of the selective reflection wavelength band of each patterned pixel at 10% or less. I do. Hereinafter, the method for producing the cholesteric liquid crystal color filter of the present invention will be described in detail.

In the production method of the present invention, the cholesteric liquid crystal composition is imagewise exposed to light with a first light, patterned, and then photopolymerized and cured with a second light (hereinafter referred to as an "exposure step"). For example, when two or more layers containing a cholesteric liquid crystal composition are formed as a liquid crystal layer, the steps are provided in a plurality of steps, and a specific step is selected. Appropriately subjecting the contact surface with the liquid crystal composition to an alignment treatment (alignment treatment step), transferring and forming a liquid crystal layer by adhesion / peeling (transfer step), and applying a cholesteric liquid crystal composition according to a specific production mode To form a liquid crystal layer (application step).

(Exposure Step) In the exposure step, a photoreactive cholesteric liquid crystal composition (hereinafter, sometimes simply referred to as “liquid crystal composition”) is exposed imagewise with a first light having a certain wavelength. After patterning, the polymerizable groups in the cholesteric liquid crystal composition are photopolymerized and cured by the second light to fix the helical structure of the liquid crystal compound to a desired selective reflection color.

When the liquid crystal composition is irradiated with the first light, the co-existing photoreactive chiral compound responds to the illuminance to change the helical structure of the liquid crystal compound, which varies depending on the structural change. Indicates a selective reflection color, and an image-like pattern is formed. Therefore, if light irradiation is performed while changing the irradiation intensity for each desired region, a plurality of colors are presented in accordance with the irradiation intensity, for example, exposure is performed through an exposure mask created by changing the light transmittance like an image. Thus, an image, that is, a colored region having different selective reflection can be simultaneously formed by one light irradiation. Irradiation with the first light can be performed without any particular limitation as long as the method can change the irradiation intensity for each desired region, in addition to the method using the exposure mask.

Here, from the viewpoint of avoiding the partial progress of the polymerization reaction at the same time as the patterning, the first light is irradiated with an illuminance (a luminous intensity which does not cause a polymerization reaction of a polymerizable monomer described later constituting the liquid crystal composition). (Irradiation intensity). Even in this illuminance region, patterning is possible, but the liquid crystal composition is maintained in an unfixed state. In this case, the patterning using the first light may be performed in an environment in which oxygen is excluded by replacing with nitrogen, or may be performed in a state where the liquid crystal composition is covered with an oxygen-blocking film or the like. You may go below. However, in the presence of oxygen, the radical quenching by the oxygen further suppresses the polymerization reactivity and facilitates the patterning by the first light, and therefore, it is preferable to perform the reaction in an environment in the presence of oxygen.

The illuminance is, specifically, 100 m
W · cm ⁻² or less is preferable, and ² mW · cm ⁻² or more is preferable in consideration of the photosensitivity of the chiral compound. The irradiation time can be appropriately selected within a range where patterning can be sufficiently performed.

As described above, after forming the image pattern by irradiating the first light, the image pattern is fixed. At the time of immobilization, polymerization curing of a polymerizable group in the cholesteric liquid crystal composition is used. As a means for causing the polymerization curing, light irradiation using a second light is further performed. In this case, the wavelength of the second light may be the same wavelength as that of the first light, or may be a different wavelength, and may be appropriately selected depending on the composition, purpose, and the like. However, a mode in which light irradiation is performed using light having the same wavelength is particularly preferable in that the irradiation wavelength and the illuminance can be made uniform and the device configuration can be simplified.

Here, that the first and second lights have the same wavelength means that the first light and the second light have substantially the same spectral profile. Light need only have substantially the same dominant wavelength region, and it is not required that the spectral profiles of both lights are completely identical. In general, even when a plurality of light sources of the same type are used, it is rare that the spectral profiles indicating the wavelength ranges of those lights completely coincide with each other. If the wavelength components are substantially the same, the light is regarded as having the same wavelength.

The second light changes the helical structure of the liquid crystal composition patterned so as to selectively reflect a predetermined hue, that is, a wavelength shift (color) from a predetermined selective reflection wavelength (desired hue). In order to fix the liquid crystal composition without causing the displacement, the increase in the half width of the selective reflection wavelength band of each patterned pixel is reduced to 10% or less (that is, the selective reflection wavelength obtained by the irradiation of the first light). Irradiation is performed at an illuminance (irradiation intensity) that can maintain the deviation (increase side) from the half width of the band at 10% or less. That is, especially when irradiating light having the same wavelength or a wavelength region overlapping with the first light, the polymerization reaction proceeds rapidly, and the chiral compound responds to the second light, thereby changing the helical structure of the liquid crystal compound. The second light is radiated so as to be cured (fixed) before the irradiation. As described above, in the presence of oxygen, the polymerization reaction rate is reduced due to the influence of radical quenching by oxygen, resulting in lack of sharpness or color shift. A cholesteric liquid crystal color filter having a uniform hue without any color shift can be manufactured.

The illuminance of the second light slightly varies depending on the kind of the liquid crystalline polymerizable monomer or chiral compound used, but is preferably 150 mW · cm ⁻² or more. Among them, 200 to 500 mW · cm ⁻² is more preferable.

The light source used for irradiating the first light and the second light is preferably a light source that emits ultraviolet light because it has a high energy and can rapidly change the structure of the liquid crystal compound and the polymerization reaction. Mercury lamps, metal halide lamps, Hg-Xe lamps and the like can be mentioned. Further, it is preferable to have a light quantity variable function.

The method for producing a cholesteric liquid crystal color filter of the present invention is not particularly limited as long as it includes at least one of the above-described exposure steps, and can be produced by a production method appropriately combined with other steps. For example, the manufacturing method according to the first and second aspects described below may be used.

[First Embodiment] (1) A step of providing at least a coating liquid cholesteric liquid crystal composition on a temporary support and forming a transfer material having a cholesteric liquid crystal layer. Between the cholesteric liquid crystal layer and the temporary support, a cushion layer containing a thermoplastic resin or the like is provided from the viewpoint of securing adhesion at the time of transfer, such as when there is a foreign substance or the like on the transfer target. It is also preferable that the surface of the cushion layer or the like is subjected to an orientation treatment (orientation treatment step) such as a rubbing treatment. (2) a step of laminating the transfer material on a light transmissive substrate; In addition to the light transmitting substrate, an image receiving material having an image receiving layer on a base may be used. Further, a cholesteric liquid crystal composition may be applied on a substrate without using the transfer material (application step). Coating can be performed by appropriately selecting from known coating methods. However, the transfer method is preferable in terms of material loss and cost.

(3) A step of peeling the transfer material from the light-transmitting substrate to form a cholesteric liquid crystal layer on the substrate (transfer step). The liquid crystal layer may be formed of a plurality of layers by further laminating after the following (4). (4) The cholesteric liquid crystal layer is imagewise irradiated with ultraviolet light of illuminance ν ¹ through an exposure mask to form a pixel pattern showing a selective reflection color, and further illuminance ν ² (ν ¹ <ν ² ; each pixel pattern) Irradiating ultraviolet rays (illuminance at which the increase in the half-value width of the selective reflection band is maintained at 10% or less) to cure the layer to form a full-color color filter (exposure step).

[Second Aspect] (1) A step of forming a cholesteric liquid crystal layer by directly providing a cholesteric liquid crystal composition on a support constituting a color filter. Here, the liquid crystal layer can be formed by applying a liquid crystal composition prepared in a coating liquid state by a known coating method such as a spin coating method. Further, an alignment film similar to the above may be formed between the cholesteric liquid crystal layer and the temporary support. The surface of the alignment film or the like is preferably subjected to an alignment treatment (alignment treatment step) such as a rubbing treatment. (2) An exposure step similar to step (4) of the first embodiment.

The thickness of the liquid crystal layer (sheet-like liquid crystal composition) functioning as a color filter is 1.5 to 4 μm.
Is preferred.

An example of a specific embodiment of the manufacturing method of the present invention will be described below with reference to FIGS. Figures 1-3
FIG. 3 is a process chart showing one embodiment of the production method of the present invention. First,
The components described above are dissolved in a suitable solvent to prepare a coating liquid cholesteric liquid crystal composition. Here, examples of the solvent include 2-butanone, cyclohexanone, methylene chloride, chloroform and the like.

As shown in FIG. 1- (A), a support 10 (hereinafter also referred to as a "temporary support") is prepared, and an acrylic resin, polyester, polyurethane or the like is formed on the support 10 by coating. Cushion layer (thermoplastic resin layer) 12
And an alignment film 1 made of polyvinyl alcohol or the like.
4 is laminated. A rubbing process is performed on this alignment film as shown in FIG. This rubbing treatment is not always necessary, but the rubbing treatment can further improve the orientation. Next, FIG.
As shown in (C), a coating liquid cholesteric liquid crystal composition is applied on the alignment film 14 and dried to form a cholesteric liquid crystal layer 16, and then a cover film 18 is provided on the cholesteric liquid crystal layer 16, Create a transfer material. Hereinafter, the transfer material is referred to as a transfer sheet 20.

On the other hand, as shown in FIG. 1- (D), another support 22 is prepared, an alignment film 24 is formed on the support in the same manner as described above, and the surface is subjected to a rubbing treatment. Hereinafter, this is referred to as a color filter substrate 26.

Next, as shown in FIG. 2E, after the cover film 18 of the transfer sheet 20 is peeled off, the surface of the cholesteric liquid crystal layer 16 of the transfer sheet 20 and the alignment film 24 of the color filter substrate 26 are removed. Are laminated so that they come into contact with the surface of each other, and laminated through a roll rotating in the direction of the arrow in the figure. Thereafter, as shown in FIG. 1- (F), the alignment film 14 of the transfer sheet 20 and the cushion layer 1 are formed.
2 and the cholesteric liquid crystal layer is transferred together with the alignment film 14 on the color filter substrate. In this case, the cushion layer 12 does not necessarily have to be peeled off together with the temporary support 10.

After the transfer, as shown in FIG. 3G, an exposure mask 28 having a plurality of regions having different light transmittances is disposed above the alignment film 14, and the first exposure mask 28 is provided through the mask 28. The cholesteric liquid crystal layer 16 is irradiated with light in a pattern. The cholesteric liquid crystal layer 16 contains a liquid crystal compound, a chiral compound, or the like so that the helical pitch varies depending on the amount of light irradiation, and a structure having a different helical pitch reflects, for example, green (G) for each pattern. Blue (B)
And a region transmitting red (R), reflecting blue (B), a region transmitting green (G) and red (R), reflecting red (R), and forming green (G) and blue (B). It is formed so as to form an area to be transmitted.

Next, as shown in FIG. 5H, the cholesteric liquid crystal layer 16 is further irradiated with ultraviolet rays at an irradiation intensity different from the light irradiation in the step (G) to fix the pattern. Thereafter, unnecessary portions (for example, remaining portions of the cholesteric liquid crystal layer 16 such as a remaining portion such as a cushion layer and an intermediate layer and unexposed portions) are removed by using 2-butanone, chloroform, or the like, so that the structure shown in FIG. As shown, a cholesteric liquid crystal layer having a BGR reflection region can be formed.

The method shown in FIGS. 1 to 3 is an embodiment of a method for manufacturing a color filter by a lamination method, but may be a method by a coating method in which a liquid crystal layer is formed directly on a color filter substrate. . In this case, when applied to the above embodiment, a cholesteric liquid crystal layer is applied on the alignment film 24 of the color filter substrate 26 shown in FIG. 1- (D), dried, and then similar to FIGS. The steps shown in ()) are sequentially performed.

These steps and materials to be used, such as a support, are described in Japanese Patent Application No. 11-1992 filed earlier by the present inventors.
No. 342896 and Japanese Patent Application No. 11-343665.

As described above, both the patterning of the liquid crystal composition and the fixation (polymerization curing) of the liquid crystal composition are performed by the light irradiation means, so that the selection of the wavelength of the second light depends on the change of the light source or the interference filter. Since there is no light, light of a uniform wavelength can be irradiated at a predetermined irradiation intensity, and it is possible to prevent a decrease in sharpness of a pattern image and a color shift, which are likely to occur in a process of fixing a liquid crystal composition. In addition, significant simplification and cost reduction of the device can be achieved. Further, as described later, since the filter film is composed of a liquid crystalline polymerizable monomer that acts with a photoreactive chiral compound, the heat resistance of the filter film itself is not impaired.

<Liquid Crystal Composition> In the production method of the present invention, a cholesteric liquid crystal composition containing at least one type of liquid crystalline polymerizable monomer, at least one type of photoreactive chiral compound, and at least one type of polymerization initiator is provided. , And the liquid crystal composition functions as a color filter film. Further, if necessary, other components such as a binder resin, a solvent, a surfactant, a polymerization inhibitor, a thickener, a dye, a pigment, an ultraviolet absorber, and a gelling agent may be contained.

(Liquid Crystalline Polymerizable Monomer) In the present invention, a liquid crystal polymerizable monomer is used as the liquid crystal compound. The liquid crystal polymerizable monomer is a nematic liquid crystal compound having a refractive index anisotropy Δn of 0.10 to 0.40 and having a polymerizable group. While in the liquid crystal state at the time of melting, for example, using an alignment substrate that has been subjected to an alignment treatment such as rubbing treatment, orienting in a predetermined direction using the photoreactivity of the coexisting chiral compound, and further irradiating light By immobilizing it, it can be used as a solid phase.

Hereinafter, specific examples of the liquid crystalline polymerizable monomer will be shown, but the present invention is not limited thereto.

[0045]

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[0046]

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[0047]

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In the above formula, n represents an integer of 1 to 1000. In each of the exemplified compounds, the side chain linking group is
Those having the following structures can also be mentioned as suitable.

[0049]

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Among the above, the nematic liquid crystal compound having a polymerizable group or a crosslinkable group in the molecule is preferable as the liquid crystal polymerizable monomer from the viewpoint of excellent curability and ensuring the heat resistance of the layer. .

The content of the liquid crystalline polymerizable monomer is 3 to the total weight of the cholesteric liquid crystal composition.
It is preferably from 0 to 98% by weight, more preferably from 50 to 95% by weight. If the content is less than 30% by weight, the orientation of the liquid crystalline polymerizable monomer may be insufficient.

(Photoreactive Chiral Compound) The photoreactive chiral compound is a compound capable of changing the helical pitch induced in the cholesteric liquid crystal composition by light irradiation (ultraviolet light to visible light to infrared light). The site (molecular structural unit) includes a chiral site and a site that undergoes a structural change by light irradiation. These sites are preferably contained in one molecule. In the present invention, in addition to the photoreactive chiral compound, a chiral compound that does not react with light, such as a chiral compound having a large temperature dependence of torsion, can be used in combination.

The chiral compound is preferably one having a large force for inducing the helical structure of the cholesteric liquid crystal composition.
For this purpose, it is preferable that the chiral site is located at the center of the molecule and the periphery thereof has a rigid structure, and the molecular weight is preferably 300 or more. In order to increase the inductive force of the helical structure due to light irradiation, it is preferable to use a material having a large degree of structural change due to light irradiation, and to bring a chiral part and a part where structural change due to light irradiation is close to each other. Further, a chiral compound having high solubility in a liquid crystalline polymerizable monomer is preferable, and its solubility parameter SP
Those having a value close to the liquid crystalline polymerizable monomer are more preferable. When the chiral compound has a structure in which one or more polymerizable bonding groups are introduced, the heat resistance of the formed liquid crystal composition film (color filter) can be improved.

Examples of the structure of the photoreactive portion whose structure is changed by light irradiation include a photochromic compound (Kingo Uchida,
Masahiro Irie, Chemical Industry, vol. 64, p. 640, 1
999, Kingo Uchida, Masahiro Irie, Fine Chemical, v
ol. 28 (9), p.15, 1999). Hereinafter, specific examples will be described, but the present invention is not limited thereto.

[0055]

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In the formula, R ¹ and R ² represent an alkyl group, an alkoxy group, an anenyl group or an acryloyloxy group.

As a chiral site, by light irradiation,
Degradation, addition reaction, isomerization, dimerization reaction and the like may occur, and the structure may be irreversibly changed. Further, as the chiral site, for example, an asymmetric carbon in which different groups are bonded to four bonds, such as a carbon atom marked with * of the compound exemplified below, corresponds to (the chemistry of liquid crystal, No. .22, Hiroyuki Nohira, Chemistry Review, p.73,199
4).

[0058]

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As the photoreactive chiral compound having both a chiral moiety and a photoisomerization unit, the following compounds can be exemplified.

[0060]

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The total content of the chiral compound in the cholesteric liquid crystal composition is not particularly limited and can be appropriately selected, but is preferably about 2 to 30% by weight.

(Polymerization Initiator) The polymerization initiator generates radicals upon irradiation with light and promotes the polymerization reaction of the polymerizable group of the liquid crystal molecules (liquid crystalline polymerizable monomer) in the cholesteric liquid crystal composition. As a result, the liquid crystal molecules are fixed at a helical pitch exhibiting a predetermined selective reflection, and the film strength of the liquid crystal composition is further improved.

The polymerization initiator can be appropriately selected from known ones, for example, p-methoxyphenyl-2,4-bis (trichloromethyl) -s-triazine, 2- (p-butoxystyryl) ) -5-Trichloromethyl 1,3,4-oxadiazole, 9-phenylacridine, 9,10-dimethylbenzphenazine, benzophenone / Michler's ketone, hexaarylbiimidazole / mercaptobenzimidazole, benzyldimethylketal, thioxanthon / amine, etc. Is mentioned.

The amount of the polymerization initiator to be added is preferably 0.1 to 20% by weight, more preferably 0.5 to 5% by weight, based on the total weight of the cholesteric liquid crystal composition. If the amount is less than 0.1% by weight, the curing efficiency at the time of light irradiation is low, so that it may take a long time. If the amount exceeds 20% by weight, the light transmittance from the ultraviolet region to the visible light region may be required. May be inferior.

(Other components) -Binder resin- As the binder resin, for example, polystyrene,
Polystyrene compounds such as poly-α-methylstyrene, cellulose resins such as methylcellulose, ethylcellulose and acetylcellulose; acidic cellulose derivatives having a carboxyl group in the side chain; acetal resins such as polyvinylformal and polyvinylbutyral;
4615, JP-B-54-34327, JP-B-58-
No. 12577, JP-B No. 54-25957, JP-A-Sho 59
-53836, JP-A-59-71048, methacrylic acid copolymer, acrylic acid copolymer, itaconic acid copolymer, crotonic acid copolymer, maleic acid copolymer,
And partially esterified maleic acid copolymers.

The homopolymer of an alkyl acrylate and the homopolymer of an alkyl methacrylate are also exemplified. In these, the alkyl group is a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an iso-butyl group.
-Butyl group, n-hexyl group, cyclohexyl group, 2-
Examples thereof include an ethylhexyl group. In addition, a polymer having a hydroxyl group to which an acid anhydride is added, a benzyl (meth) acrylate / (homopolymer of methacrylic acid) acrylic acid copolymer or benzyl (meth) acrylate / (meth) acrylic acid / other monomer And the like.

The content of the binder in the cholesteric composition is preferably from 0 to 50% by weight,
30% by weight is more preferred. The content is 50% by weight.
If it exceeds 300, the orientation of the liquid crystal compound may be insufficient.

-Polymerization Inhibitor- A polymerization inhibitor may be added for the purpose of improving the storage stability. Examples of the polymerization inhibitor include hydroquinone, hydroquinone monomethyl ether, phenothiazine, benzoquinone, and derivatives thereof. These are added in an amount of 0 to 10% by weight based on the weight of the liquid crystalline polymerizable monomer. It is more preferable to add 0 to 5% by weight.

[0069]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 <Preparation of Photosensitive Transfer Material> A rubbed polyethylene terephthalate base film (PET film) having a thickness of 75 μm was prepared as a temporary support, and the following composition was formed on the PET film. Apply the coating solution for the thermoplastic resin layer with a spin coater, and heat
After drying for 15 minutes, a thermoplastic resin layer having a thickness of 15 μm was formed.

[Composition of coating liquid for thermoplastic resin layer] Styrene-acrylic acid copolymer ... 15 parts by weight (copolymerization ratio = 60/40, weight average molecular weight 8000) 2,2 -bis (4 -(Methacryloxypolyethoxy) phenylpropane) 7 parts by weight Fluorosurfactant 1.5 parts by weight (F-176PF, manufactured by Dainippon Ink Co., Ltd.) Propylene glycol monomethyl ether・ 28 parts by weight ・ Methyl ethyl ketone ・ ・ ・ 27 parts by weight

Next, a coating liquid for an intermediate layer prepared from the following composition was applied on the above-mentioned thermoplastic resin layer by a spin coater, dried in an oven at 100 ° C. for 2 minutes and 1.6 μm.
An m-thick intermediate layer was laminated. Further, the surface of the intermediate layer was rubbed with a nylon cloth.

[Composition of Coating Solution for Intermediate Layer] Polyvinyl alcohol: 15 parts by weight (PVA205, manufactured by Kuraray Co., Ltd.) Polyvinylpyrrolidone: 6 parts by weight (PVP-K30, Gokyo Sangyo Co., Ltd.)・ Methanol: 173 parts by weight ・ Ion-exchanged water: 211 parts by weight

Next, as a coating solution for a photosensitive resin layer, a coating solution prepared according to the following formulation was applied onto the above-mentioned intermediate layer by a spin coater, and dried in an oven at 100 ° C. for 2 minutes to form a photosensitive resin layer. Was formed. Further, a 12 μm thick polypropylene film as a cover film is laminated on the layer at room temperature, and a thermoplastic resin layer, an intermediate layer, a photosensitive resin layer, and a cover film are laminated on a PET film in this order. The material was obtained.

[0075]

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<Manufacturing Method of Cholesteric Liquid Crystal Color Filter> (1) Preparation of Filter Substrate A polyimide alignment film coating solution was applied on a glass substrate by a spin coater, dried in a 100 ° C. oven for 5 minutes, and then dried in a 250 ° C. oven. For 1 hour to form an alignment film. Further, the surface of the film was subjected to an orientation treatment by a rubbing treatment to produce a glass substrate with an orientation film.

(2) Formation of Filter Layer The cover film is peeled off from the photosensitive transfer material obtained as described above, and the surface of the photosensitive resin layer is brought into contact with the surface of the alignment film of the glass substrate provided with the alignment film. Using a laminator (Fast Laminator 8B-550-80, manufactured by Taisei Laminator Co., Ltd.), pressurizing at ² kg / m ² ,
Lamination was performed under a roller temperature of 130 ° C. and a feeding condition of 0.2 m / min. Thereafter, the PET film was peeled off from the bonded state at the interface with the thermoplastic resin layer to remove the PET film.

Subsequently, the photosensitive resin layer was held on a hot plate at 110 ° C. for 5 minutes so as to be in contact with the surface of the glass substrate, so that the photosensitive resin layer was colored. Further, on the photosensitive resin layer, the transmittance is different in three stages (0%, 46%, 92%), and the respective regions are arranged corresponding to red pixels, green pixels, and blue pixels. An ultra-high pressure mercury lamp was arranged via a photomask and an ND filter, and irradiation was performed with the ultrahigh pressure mercury lamp through the photomask and the ND filter to perform patterning. The irradiation energy at this time is 5 for blue pixels.
The irradiation intensity was 00 mJ / cm ² and the irradiation intensity was 15 mW / cm ² . At this time, the half width of the reflection peak of the red pixel is 6
It was 2 nm.

The photomask and the ND filter were removed, and the irradiation energy was 1000
The entire surface was exposed at mJ / cm ² and irradiation intensity of 300 mW / cm ² , and polymerized and cured. At this time, the half width of the reflection peak of the red pixel was 65 nm.

Thereafter, the thermoplastic resin layer and the intermediate layer on the glass substrate were removed using a predetermined processing solution (T-PD2, manufactured by Fuji Photo Film Co., Ltd.). Further, in order to harden the filter portion (photosensitive resin layer), it was baked in an oven at 200 ° C. for 10 minutes to obtain a color filter substrate on which red, green, and blue pixel patterns were formed.

As described above, both the patterning of the liquid crystal compound and the polymerization and curing (fixation) can be performed by irradiation with light, and even if irradiation is performed again for polymerization and curing, the reflection peak of the red pixel after patterning is obtained. Increase the half width of
% Or less. The obtained color filter is highly sharply patterned, has no color shift, has a uniform hue, and does not need to be equipped with a plurality of light sources and interference filters, so that cost reduction and simplification of the device can be achieved. I was able to plan.

(Example 2) A glass substrate with an alignment film provided with an alignment film subjected to a rubbing treatment was prepared in the same manner as in Example 1, and the photosensitive resin layer prepared in Example 1 was formed on the alignment film. The coating solution for application was applied by a spin coater and dried in an oven at 100 ° C. for 2 minutes. Then, the photosensitive resin layer is colored by holding on a hot plate at 110 ° C. for 5 minutes so as to be in contact with the surface of the glass substrate, and the transmittance on the photosensitive resin layer is different in three steps (0% , 46%, 92
%), An ultra-high pressure mercury lamp is arranged via a photomask and an ND filter, each region of which is arranged corresponding to a red pixel, a green pixel, and a blue pixel, and an ultrahigh pressure mercury lamp is passed through the photomask and the ND filter. Irradiation was performed with a mercury lamp to perform patterning. The irradiation energy at this time is 500 mJ / cm ² for the blue pixel, and the irradiation intensity is 30.
mW / cm ² . At this time, the reflection peak of the red pixel
The full width at half maximum was 60 nm.

The photomask and the ND filter were removed, and the irradiation energy was 1000
The entire surface was exposed at mJ / cm ² and irradiation intensity of 300 mW / cm ² , and polymerized and cured. At this time, the half width of the reflection peak of the red pixel was 63 nm. Further, in order to harden the filter part (photosensitive resin layer),
After baking for 0 minutes, a color filter substrate on which red, green, and blue pixel patterns were formed was obtained.

As described above, both the patterning of the liquid crystal compound and the polymerization and curing (fixation) can be performed by light irradiation, and the reflection peak of the red pixel after patterning can be obtained even if irradiation is performed again for polymerization and curing. Increase the half width of
% Or less. The obtained color filter is highly sharply patterned, has no color shift, has a uniform hue, and does not need to be equipped with a plurality of light sources and interference filters, so that cost reduction and simplification of the device can be achieved. I was able to plan.

[0085]

According to the present invention, it is possible to perform both patterning and polymerization curing (fixation) of a liquid crystal compound by irradiating light, and to form a pattern with high sharpness without color shift and uniform hue. It is possible to provide a method of manufacturing a cholesteric liquid crystal color filter capable of producing a low-cost cholesteric liquid crystal color filter. Moreover,
The filter film itself does not impair heat resistance. Further, according to the present invention, it is not necessary to provide a plurality of light sources and interference filters, and the configuration of the apparatus can be simplified.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a part of a step of manufacturing a cholesteric liquid crystal color filter of the present invention.

FIG. 2 is a schematic view showing a part of a step of manufacturing a cholesteric liquid crystal color filter of the present invention.

FIG. 3 is a schematic view showing a part of a step of manufacturing a cholesteric liquid crystal color filter of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Support (temporary support) 12 Cushion layer (thermoplastic resin layer) 14, 24 Alignment film 16 Cholesteric liquid crystal layer (liquid crystal composition) 18 Cover film 20 Transfer sheet 22 Substrate 26 Color filter substrate 28 Exposure mask

Continued on the front page F term (reference) 2H025 AB13 AC01 BC49 BH00 CA01 CA09 CA14 CA27 CA28 FA06 2H048 BA43 BA45 BA47 BA48 BA64 BB02 BB42 2H091 FA02Y FB02 FB04 FC10 FC26 FD04 FD14 FD24 GA17 LA03 LA11 LA13 LA15 2H096A A28

Claims (3)

[Claims] 1. A cholesteric liquid crystal composition comprising at least one liquid crystallizable polymerizable monomer, at least one photoreactive chiral compound, and at least one polymerization initiator is image-wise formed by a first light. After exposure and patterning, the method includes at least one step of photopolymerizing and curing by second light, and the illuminance of the first light is an illuminance that does not cause a polymerization reaction of the polymerizable monomer, A method for manufacturing a cholesteric liquid crystal color filter, wherein the illuminance of the second light is an illuminance capable of maintaining an increase in a half-value width of a selective reflection wavelength band of each patterned pixel at 10% or less. 2. The method according to claim 1, wherein the spectral profiles of the first light and the second light are substantially the same. 3. The method for manufacturing a cholesteric liquid crystal color filter according to claim 1, wherein the patterning by the first light is performed in the presence of oxygen.