JP2003131187A - Selective reflection film and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a selective reflection film, by which a uniform hue with high color purity (in particular a green or a red hue) is obtained and color separation (patterning) is carried out with high accuracy without being affected by irradiation unevenness or the like in patterning. SOLUTION: The method for manufacturing the selective reflection film is characterized by making a liquid crystal composition containing a liquid crystal compound, a photo-reactive chiral compound with an isomerizing absorption band in a visible ray region and a polymerization initiator be irradiated with either circularly or elliptically polarized light with the direction identical to the helical twist direction of the liquid crystal so as to realize a picture and forming a pattern exhibiting the selective reflection corresponding to the irradiation. In a preferable manner, the photo-reactive chiral compound has the isomerizing absorption band in 490-570 nm or 630-690 nm and further the wavelength of the circularly or elliptically polarized light is 490-570 nm or 630-690 nm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a selective reflection film such as a color filter or a retardation film, which is preferably used for a display device such as an LCD, and a method for producing the same, and more specifically to a liquid crystal composition exhibiting selective reflection. The present invention relates to a selective reflection film which is obtained by irradiating an object with light and has high color reproducibility and display image quality, and a manufacturing method thereof.

[0002]

2. Description of the Related Art For example, a color filter used in a color liquid crystal display or the like generally has pixels of red (R), green (G) and blue (B), and a black between them for the purpose of improving display contrast. And a matrix. As a method for manufacturing such a color filter, in recent years, there is a demand for a manufacturing method capable of easily manufacturing a high-quality color filter with high efficiency and little material loss,
Further, in terms of the performance of the color filter, it is required that the transmittance and the color purity are high. Therefore, in recent years, a color filter mainly containing a liquid crystalline material (particularly, cholesteric liquid crystal) has been widely studied.

A color filter using a liquid crystal composition containing cholesteric liquid crystal as a main component is a polarization-use type color filter which reflects light of a certain wavelength and transmits other light to display an image. High utilization efficiency, transmittance,
Excellent in color purity. Since a uniform thickness can be easily formed in manufacturing, a method of forming a film by using a spin coat method or the like was generally used, but it is disadvantageous in terms of large material loss and cost. A production method using a photoreactive chiral compound is useful. That is, when a liquid crystalline composition containing a photoreactive chiral compound is used, when the light having the sensitive wavelength of the chiral compound is irradiated in a pattern, the isomerization of the chiral compound is caused depending on the intensity (irradiation amount) of the irradiation energy. As a result, the helical pitch (helix twist angle) of the liquid crystal compound changes, and as a result, the desired selective reflection color can be easily formed for each pixel only by pattern exposure with a light amount difference, and material loss is reduced. Therefore, the number of steps can be reduced and the cost can be reduced.

However, the image characteristics required for a color image in recent years are high, and in particular, in a color filter, it is indispensable to have a high resolution in addition to a high hue purity for selective reflection. However, as described above, the selective reflection wavelength can be sequentially changed from the short wavelength to the long wavelength side (blue (B) → green (G) → red (R)) in accordance with the increase of the irradiation light amount. As compared with the irradiation light amount region a ^{1 in} which the selective reflection of red is obtained, the irradiation light amount is 570 nm particularly from the short wavelength region.
Since the change of the wavelength to the long-wave side is extremely steep until reaching the vicinity, the irradiation light amount range a ^{3 at} which the selective reflection of green is obtained is very narrow, and if uneven exposure or the like occurs during irradiation, yellowish or bluish tint is produced. There was a problem that it became a tinged green color, a high-purity green color as a primary color could not be obtained, and the hue became uneven.
Further, in the case of showing selective reflection of red, if the absorption edge shifts even a little, the display tends to become dark due to an orange tint or reduced visual sensitivity. Moreover, when RGB are arrayed, the boundary between pixels (pixel boundary) where the hues are adjacent to each other blurs the color fraction, lowers the resolution, and consequently lowers the patterning accuracy.

On the other hand, other optical films such as retardation films and circularly polarized light reflectors are required to have a large intrinsic birefringence (Δn) of the film from the viewpoint of obtaining good optical characteristics. By increasing the thickness of the film, Δn of the film can be increased, but this is disadvantageous in terms of cost, and a thin film is required in terms of cost reduction.

On the other hand, when a film (layer) containing a liquid crystalline composition (for example, a color filter film, a retardation film, etc.) is formed by coating, particularly in the case of a low-molecular liquid crystal, the liquid crystal molecules are horizontal (to the substrate) on the substrate side. Even if the alignment treatment is performed so that one side of the color filter forming layer is at the air interface, the liquid crystal molecules stand vertically at the air interface side, and the tilt angle (pretilt angle) of the liquid crystal molecules increases in the thickness direction of the layer. A continuously changing state occurs. Therefore, usually, it is necessary to sandwich both sides of the layer with an alignment film, but when the liquid crystalline composition is polymerized and used as an optical film, at least one side is aligned after polymerization for weight reduction and thinning. There is also a problem that the film needs to be peeled off, which increases the number of steps such as installation and removal of the alignment film and the amount of waste material.

[0007]

As described above, in a manufacturing method using a liquid crystalline material containing a photoreactive chiral compound, a favorable alignment treatment is easily performed, and color purity due to color misregistration (particularly green or Selective reflection film (color filter, retardation film, circularly polarized light reflection plate, etc.) that does not cause deterioration of red) or unevenness of hue and always has stable and high resolution with good image characteristics and optical characteristics of color fractionation. The technology that can make
The current situation is that it has not been established yet.

From the above, it is an object of the present invention to solve the above-mentioned problems of the prior art and achieve the following objects.
That is, the present invention is capable of performing a simple and favorable alignment treatment, avoids a decrease in color purity and resolution due to hue shift due to irradiation unevenness at the time of patterning, and provides a uniform and high hue purity (especially green color). Alternatively, a method for producing a selective reflection film capable of obtaining a red color) and performing color fractionation (patterning) with high accuracy, and a hue and hue uniformity for selective reflection,
In particular, it is an object of the present invention to provide a selective reflection film which is excellent in the hue of green or red and its uniformity, has high resolution, excellent color fractionation (patterning accuracy), and excellent optical characteristics.

[0009]

The present inventors have obtained the following findings regarding the image / optical characteristics of a selective reflection film (particularly, color purity for selective reflection, improvement in hue uniformity, and high resolution).
A selective reflection film containing a photoreactive chiral compound, for example, when producing a color filter using a photoreactive cholesteric liquid crystal composition, when subjecting the liquid crystalline composition (liquid crystal layer) to pattern exposure, areas with different amounts of transmitted light are applied. It is possible to perform patterning by a single exposure using the mask provided, but in particular, it is difficult to always obtain a green hue having a constant chromaticity because the light amount range capable of forming selective reflection of green (G) is narrow. Further, the red color (R) that is selectively reflected is tinged with orange even if its absorption edge is slightly shifted, and the visibility is likely to be lowered, and the display tends to be dark.
Furthermore, it is difficult to control the intermediate color from short wavelength to around 570 nm in other applications such as printed matter and anti-counterfeiting display.

From the above findings, the above-mentioned problem is to use circularly polarized light or elliptically polarized light in the same direction as the twist direction of the spiral of liquid crystal for patterning the cholesteric liquid crystal composition, and This is achieved based on the fact that the absorption wavelength of the chiral compound is the same as or near the absorption wavelength, and the specific means is as follows. <1> A liquid crystal composition containing a liquid crystal compound having at least one polymerizable group (preferably a nematic liquid crystal compound), a photoreactive chiral compound having absorption capable of isomerization in the visible light region, and a polymerization initiator. Light an object like an image (wavelength λ ¹ )
A method for producing a selective reflection film, which comprises irradiating and forming a pattern exhibiting selective reflection in accordance with the irradiation, wherein either circularly polarized light or elliptically polarized light in the same direction as the twist direction of the liquid crystal spiral is used for the light irradiation. This is a method of manufacturing a selective reflection film, characterized in that

<2> The liquid crystal composition is irradiated with light having a wavelength of λ ¹ to form an exposure dose distribution in the liquid crystal composition, and a state in which selective reflection corresponding to the exposure dose distribution is exhibited, The liquid crystal composition in this state is irradiated with light having a wavelength of λ ² to polymerize and cure imagewise to form a multicolor pattern.
¹ is the method for producing a selective reflection film according to <1>, wherein the light is either circularly polarized light or elliptically polarized light having the same direction as the twist direction of the liquid crystal.

<3> The liquid crystal composition has a wavelength λ¹The light of
Irradiate image-wise and show selective reflection according to the irradiation.
Then, the wavelength λ²Image by illuminating
The number of steps to polymerize and cure to form a single color pattern is reduced
Including one step, the wavelength λ ¹The light of the twist of the liquid crystal spiral
Either circularly polarized light or elliptically polarized light in the same direction
The method for producing a selective reflection film according to <1> above. <4> Wavelength λ¹Change the light irradiation amount of
By repeating the process of forming a monochrome pattern n times,
In the above <3>, which forms a multicolor pattern of n colors
It is a manufacturing method of the selective reflection film described.

<5> A liquid crystal composition which is in a state of exhibiting selective reflection of the first color is irradiated with light of wavelength λ ² to polymerize and cure imagewise to form a monochromatic pattern, and then the first color The wavelength λ ¹
By changing the irradiation amount of the light of (1) to (n-1) steps and repeating the process of forming a monochromatic pattern (n-1) times.
The method for producing a selective reflection film according to <3>, wherein a multicolor pattern of colors is formed.

<6> The photoreactive chiral compound is 490
Light having a wavelength of λ ¹ has a isomerizable absorption in the wavelength region of ˜570 nm or 630 to 690 nm and has a wavelength of 49
The method for producing a selective reflection film according to any one of <1> to <5>, which is light having a wavelength of 0 to 570 nm or 630 to 690 nm. <7> The wavelength λ ¹ (nm) is (λ-50) ≦ with respect to the absorption wavelength λ (nm) of the photoreactive chiral compound which can be isomerized.
The method for producing a selective reflection film according to any one of <1> to <6>, wherein λ ¹ ≦ (λ + 50) is satisfied. <8> The above-mentioned <1> in which the liquid crystalline composition contains an air interface aligning agent.
> To <7>, the method for producing a selective reflection film. <9> A selective reflection film obtained by the method for producing a selective reflection film according to any one of <1> to <8>.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, patterning is carried out using either circularly polarized light or elliptically polarized light (wavelength λ ¹ ) in the same direction as the twist direction of the liquid crystal, and preferably wavelength λ ¹ (λ- 50) ≦ λ ¹ ≦ (λ + 50) [λ: absorption wavelength (nm) capable of isomerizing photoreactive chiral compound]. Hereinafter, the selective reflection film of the present invention and the method for manufacturing the same will be described in detail.

<Method for producing selective reflection film> In the method for producing a selective reflection film of the present invention, a liquid crystalline composition capable of exhibiting selective reflection (hereinafter, also referred to as "cholesteric liquid crystal composition" or "cholesteric liquid crystal layer"). On the other hand, circularly polarized light or elliptically polarized light in the same direction as the twist direction of the liquid crystal is imagewise irradiated to form a pattern showing selective reflection according to the irradiation (amount) (hereinafter, this operation is generally referred to as " Sometimes referred to as "exposure step".). Here, the “twisting direction of the spiral of the liquid crystal” refers to the direction (right circle / left circle direction) in which the structure in which the liquid crystal molecules are spirally arranged is twisted.

That is, in the exposure step, light (wavelength λ) is entirely or partially included in a desired region to be colored.
Irradiation (patterning) of ¹ circularly polarized light or elliptically polarized light
Then, the photoreactive chiral compound reacts with the light, and the helical pitch of the liquid crystal changes due to the structural change due to trans-cis isomerization or a chemical reaction, thereby exhibiting a desired selective reflection state, that is, a desired hue. Then, preferably, light (wavelength λ ² (≠ λ ¹ )) is further irradiated to polymerize and cure only a desired region to fix the helical pitch of the liquid crystal. In the present invention, a uniform hue with high color purity (particularly green or red) can be obtained particularly effectively, and particularly highly accurate color fractionation (patterning) is possible. Polarized light) is preferable, and an embodiment in which circularly polarized light is imagewise irradiated is particularly preferable.

Further, since circularly polarized light or elliptically polarized light in the same direction as the twist direction of the spiral of the liquid crystal is used, for example, 490 nm ≦
When patterning with green light with λ ¹ ≤ 570 nm, the hue selectively reflected changes from blue to green with irradiation, and most of the irradiation light is reflected, making it difficult to change the twist. It is possible to cause a twist change to such an extent that the productivity can be secured while expanding the light amount range in which the selective reflection is obtained.

In the method for producing a selective reflection film according to the first aspect of the present invention, a circularly polarized light or an elliptically polarized light having a wavelength λ ¹ (same as the twist direction of the spiral of liquid crystal) is applied to a liquid crystal composition capable of exhibiting selective reflection. Direction) to form an exposure dose distribution, and a state of exhibiting selective reflection according to the exposure dose distribution is obtained, and then the liquid crystalline composition in this state is further irradiated with light of wavelength λ ² to form an image. It can be preferably carried out by including a step (exposure step) of polymerizing and curing to form a multicolor pattern.

Therefore, the liquid crystal composition (preferably,
(Indicating a non-liquid crystal state), for example, through the exposure step once through a mask or the like having regions having different amounts of transmitted light, the entire desired region of the liquid crystalline composition (cholesteric liquid crystal layer) You can form the exposure distribution at once,
A color filter showing selective reflection of a plurality of colors can be easily obtained. The light of wavelength λ ¹ may be applied to any area of the liquid crystal layer, and may be applied to the entire surface of the liquid crystal layer, or may be applied only to a portion including a desired target area to be colored. Even in the case of this embodiment, a uniform hue with high color purity (particularly green or red) can be obtained, and color fractionation (patterning) can be performed with high accuracy. Further, the diffusion of the chiral compound isomerized by the light of different light amount for each pixel between the regions (colored pixels) adjacent to each other at the time of irradiating the light of λ ² can be prevented, resulting in the hue at the pixel boundary portion. It is also possible to effectively prevent a decrease in color purity or resolution due to bleeding of the ink.

As a specific constitutional aspect of this embodiment, a step of irradiating the liquid crystalline composition with light of λ ¹ to form an exposure dose distribution in the liquid crystalline composition, and a liquid crystallinity in which the exposure dose distribution is formed. A step of raising the temperature of the composition (preferably transitioning from a non-liquid crystal state to a liquid crystal state) to form a state (region) of selective reflection according to the exposure dose distribution; and the liquid crystal in which the state is formed The step of irradiating the composition with light of λ ² (≠ λ ¹ ) to polymerize or crosslink the composition to cure the composition may be employed.

The method for producing a selective reflection film according to the second aspect of the present invention comprises a liquid crystalline composition capable of exhibiting selective reflection (preferably,
Circularly polarized light or elliptically polarized light having the wavelength λ ¹ (in the same direction as the twist direction of the liquid crystal helix) is irradiated to the (non-liquid crystal state) (preferably, the temperature is raised to transition from the non-liquid crystal state to the liquid crystal state). ) At least a step (exposure step) of forming a monochromatic pattern by irradiating the region of the state with light of wavelength λ ² to polymerize and harden the image after the state of exhibiting a monochromatic selective reflection according to the irradiation is formed. It can be preferably implemented by including one step. Here, the "state showing selective reflection of a single color" means a state in which a region which has not been polymerized and cured yet exhibits a desired single color by irradiation with light having a wavelength λ ¹ .

Therefore, in this embodiment, a pattern exhibiting a single color selective reflection can be formed by passing through the exposure step once, and a color filter exhibiting a plurality of colors selective reflection can be formed by repeating the step a plurality of times. Can be obtained. Irradiation with light of wavelength λ ¹ may be performed on any region of the cholesteric liquid crystal layer, may be performed on the entire surface of the cholesteric liquid crystal layer, or may be performed only on a portion including a desired target region to be colored, It may be performed in an imagewise manner, and it is preferable that the irradiation area is not limited from the viewpoint that the manufacturing process is not restricted and the process can be simplified.

Further, in both the first and second aspects of the present invention, by irradiating the light of wavelength λ ² after the irradiation of light of wavelength λ ¹ to fix the alignment of the liquid crystal molecules, Since the selective reflection wavelength is kept unchanged and an image is formed (patterned), the irradiation with the light having the wavelength λ ² is performed in a manner that the composition can be polymerized and cured in an imagewise manner by the irradiation. Therefore, it is not always necessary to irradiate the light of λ ² imagewise, and for example, the last hue formation (formation of the third color in the case of three RGB colors) may be formed in the entire area that is not fixed. It is sufficient to irradiate the entire surface, and the entire surface is polymerized and cured imagewise to form a final pattern.

In the second aspect, it is sufficient that the exposure step includes at least one step, and specifically, it may be either aspect A or aspect B below. Among them, the selective reflection film can be particularly preferably produced by the two aspects. Here, a cholesteric liquid crystal color filter will be described as an example of the selective reflection film.

In the aspect A according to the second aspect, the exposure step is included at least one step, and the wavelength λ
^The process of forming a monochromatic pattern (that is, the exposure process) is repeated n times by changing the irradiation amount of circularly polarized light or elliptically polarized light (in the same direction as the twist direction of the liquid crystal spiral) of ¹ (visible light region) in n steps. As a result, a multicolor pattern of n colors can be formed. In the above, the light irradiation amount is n
Changing to a step does not necessarily mean that the irradiation amount changes in order, but in each step of the exposure process performed n times, the irradiation amount of light is set to different irradiation amounts so as to show desired selective reflection. Say that.

In this embodiment, for example, R (red), G (green),
And a color filter consisting of B (blue) (n = 3)
In the case of producing, the wavelength λ ¹ (preferably 49) is selected so that the selective reflection wavelength showing the hue of the first color (for example, R) can be obtained for the liquid crystal composition (cholesteric liquid crystal layer).
0 to 570 nm or 630 to 690 nm wavelength light)
Circularly polarized light or elliptically polarized light (in the same direction as the twist direction of the spiral of the liquid crystal) with the irradiation amount h ^α (step 1), and then the wavelength λ
^After irradiating ² (less than 400 nm) light like a desired image to form a first color pattern (for example, R pixel), a selective reflection wavelength showing a second color hue (for example, G) is obtained. , Circularly polarized light or elliptically polarized light of wavelength λ ¹
Irradiation at ^β (stage 2), followed by irradiation with light of wavelength λ ^{2 in} a desired image pattern to form a second color pattern (for example, G pixel), and a third color hue (for example, B). The circularly polarized light or the elliptically polarized light having the wavelength λ ¹ is irradiated with the irradiation amount h ^γ (step 3) so that the selective reflection wavelength shown in FIG.
^{The second} light is irradiated (as desired, a desired image is formed) to form a third color pattern (for example, B pixel). In this aspect, it is possible to eliminate the unevenness of the helical structure (pitch) of the liquid crystal due to uneven irradiation, etc., and it is possible to produce a sharp and high-resolution cholesteric liquid crystal color filter having high color purity and hue uniformity.

Further, in the aspect B according to the second aspect,
The cholesteric liquid crystal layer (liquid crystalline composition) in the state of exhibiting selective reflection of the first color is previously irradiated with light having a wavelength λ ² (less than 400 nm) to polymerize and cure in an imagewise manner to form a monochromatic pattern. The irradiation amount of circularly polarized light or elliptically polarized light of wavelength λ ¹ (visible light region) (the same direction as the twist direction of the liquid crystal helix) is set to (n−1) steps so as to show selective reflection of a wavelength different from the first color. Then, the step of forming a single-color pattern (that is, the exposure step) is repeated (n-1) times to form a multicolor pattern of n colors. As in the case of the aspect A, changing the irradiation amount of light to the (n-1) step does not necessarily mean that the irradiation amount is sequentially changed, but each step of the exposure step performed (n-1) times In the above, it means that the light irradiation amounts are all different so as to show desired selective reflection.

In this embodiment, the liquid crystal composition is formed in advance in a state of exhibiting a predetermined selective reflection color (first color selective reflection) before shifting to the exposure step. As a result, the number of steps can be further reduced, and the first color having better color purity and hue uniformity can be easily formed in the wavelength region that sharply changes with respect to the irradiation light amount, and the cost can be reduced. You can also plan. As a method for setting a predetermined selective reflection color (first color selective reflection) in advance, for example, a cholesteric liquid crystal layer is provided on the surface of the alignment film, and the wavelength λ
² Heat before the irradiation of light, transfer the cholesteric liquid crystal layer using a transfer material (the following aspect (1)), or apply the cholesteric liquid crystal layer by coating (the following aspect (2))
At the same time, the amount of light h ^α that can cause the liquid crystal layer to exhibit the selection wavelength of the first color over the entire surface or a part thereof including the region where the color is to be obtained.
The circularly polarized light or the elliptically polarized light (wavelength λ ¹ ) is irradiated.

For example, in the case of a cholesteric liquid crystal color filter (n = 3) consisting of three colors of RGB, since it is already in the state of exhibiting selective reflection of the first color (for example, R), the wavelength λ
^After irradiating ² (less than 400 nm) light like a desired image to form a first color pattern (for example, R pixel), a selective reflection wavelength showing a second color hue (for example, G) is obtained. , Circularly polarized light having wavelength λ ¹ (preferably light having a wavelength of 490 to 570 nm or light having a wavelength of 630 to 690 nm) or elliptically polarized light (in the same direction as the twist direction of the spiral of the liquid crystal), the irradiation amount h ^β
Irradiation in (Stage 1), followed by irradiation with light of wavelength λ ^{2 in} a desired image pattern to form a pattern of the second color (for example, G pixels), and further to show a hue of the third color (for example, B). The circularly polarized light or the elliptically polarized light having the wavelength λ ¹ is irradiated with the irradiation amount h ^γ (step 2) so that the selective reflection wavelength is obtained, and then the wavelength λ ²
To irradiate the above-mentioned light (as desired with a desired image) to form a third color pattern (for example, B pixel). Also in this aspect, it is possible to eliminate the nonuniformity of the helical structure (pitch) of the liquid crystal due to uneven irradiation, etc., and to manufacture a sharp and high-resolution cholesteric liquid crystal color filter having high color purity and hue uniformity.

<Exposure Step> In the exposure step according to the present invention, hue adjustment (coloring by selective reflection) for bringing the liquid crystalline composition (cholesteric liquid crystal layer) into a desired selective reflection state and polymerization of the cholesteric liquid crystal layer. Both patterning by curing and fixing of the selective reflection wavelength are performed by light irradiation. That is, after the photoreactive chiral compound is brought into a liquid crystal alignment state that exhibits desired selective reflection by light in the visible light region (preferably a wavelength region of 400 nm or more) which can be sensitively sensitive, the polymerization initiator is sensitively sensitive. Possible wavelength λ
² (less than 400 nm) photopolymerizes and cures,
The helical structure of the liquid crystal compound is fixed to a desired selective reflection color.

A more specific description will be given below. First, when circularly polarized light or elliptically polarized light having a wavelength λ ¹ is irradiated to the cholesteric liquid crystal layer, the coexisting photoreactive chiral compound is exposed to light and the helical structure of the nematic liquid crystal compound is changed according to its illuminance. A different selective reflection color is shown depending on the change. Therefore, a desired hue is exhibited by changing the irradiation amount for each desired region, and in this state, a light of λ ² is imagewise irradiated and cured (fixed) to obtain a patterned monochromatic image ( Exposure process). In the first aspect, a multicolor liquid crystal color filter can be produced by one exposure step, and in the second aspect, the exposure step is repeated.

In the present invention, circularly polarized light or elliptically polarized light in the same direction as the twist direction of the spiral of the liquid crystal is used as the light of the wavelength λ ¹ (visible light region). For example, 490nm ≦ λ ¹
When patterning with green light of ≦ 570 nm, as described above, the hue selectively reflected depending on the irradiation amount is from blue to green, and most of the irradiation light is reflected, but shows the selective reflection. Polarized light traveling in a circular motion in the same direction as the twisting direction of the helical structure of the liquid crystalline composition easily penetrates into the liquid crystalline composition and maintains the twisting change due to irradiation, and the pitch (twisting angle) at which red selective reflection is exhibited. ) Can continue to change.

Further, as the wavelength of the light of the wavelength λ ¹ ,
It is preferable to set the wavelength close to the photosensitizing wavelength range of the photoreactive chiral compound, particularly the photosensitizing peak wavelength belonging to the visible light region (preferably a wavelength region of 400 nm or more) from the viewpoint of obtaining sufficient patterning sensitivity, In the present invention, from the viewpoint of ensuring color purity and hue uniformity of green or red in particular, 490 to 570 nm or 6
It is particularly preferable to use light of 30 to 690 nm. Specifically, the wavelength λ ¹ is 490 to 490 in a photoreactive chiral compound having absorption capable of being isomerized to a wavelength of 490 to 570 nm.
Wavelength 630-690nm, combining 570nm light
A mode in which a photoreactive chiral compound having isomerizable absorption is combined with light having a wavelength λ ¹ of 630 to 690 nm is preferable.

Further, the wavelength λ ¹ (nm) of the patterning light satisfies (λ-50) ≦ λ ¹ ≦ (λ + 50) with respect to the isomerizable absorption wavelength λ (nm) of the photoreactive chiral compound. Is particularly preferred. Above all, (λ-30) ≦
Most preferably, λ ¹ ≦ (λ + 30).

In the visible light region, blue (B) to green (G)
Since a wavelength exhibiting red color (R) is included, by using a chiral compound having light absorption in a desired wavelength range within the above range, as shown in FIG. Since it is possible to expand the light amount range a ² corresponding to a certain area, for example, the light amount range a ³ showing the selective reflection of green when combined as described above, it is affected by a slight change in the light amount (irradiation unevenness, etc.). It is possible to stably obtain a desired hue uniformly. As a result, it is possible to eliminate the unevenness of the spiral change of the liquid crystal due to the change of the light amount due to the uneven irradiation,
It is possible to prevent deterioration of hue purity and uniformity.
Note that FIG. 1 shows the relationship between the amount of irradiation light to the photoreactive liquid crystalline composition and the selective reflection wavelength. Further, since the photosensitizing peak wavelength of the polymerization initiator used in combination is generally around 400 nm, it is possible to effectively prevent the hue shift in the process of fixing the spiral structure after patterning as described later.

The wavelength of the light having the wavelength λ ² is preferably set to a photosensitive wavelength region of the polymerization initiator, in particular, a wavelength close to the photosensitive peak wavelength in order to obtain sufficient photopolymerization sensitivity. Further, the irradiation amount and the illuminance (irradiation intensity) of the light having the wavelengths λ ¹ and λ ² are not particularly limited and can be appropriately selected according to the material used so that sufficient photosensitivity can be obtained.

As a method for obtaining the circularly polarized light or the elliptically polarized light having the wavelength λ ¹ , for example, a polarizing plate, a quarter wavelength plate (λ
/ 4 plate) or the like, a method of combining a linear polarizer and a λ / 4 wave plate, and the like, and the light source used for the irradiation has high energy, structural change of the liquid crystal compound and polymerization reaction. Visible light (preferably 4
A light source that emits ultraviolet rays (00 nm or more) is preferable, and examples thereof include a xenon lamp. However, a light source that emits the following ultraviolet rays may be used with the polarizing plate and the λ / 4 plate interposed. Further, it is preferable to have a light amount variable function. The wavelength λ
^As the light source used for the irradiation of the light of ^2, the light source that emits ultraviolet rays is preferable because it has high energy and can rapidly change the structure of the liquid crystal compound and the polymerization reaction. For example, a high pressure mercury lamp, a metal halide lamp, a Hg-Xe lamp. Etc. Further, it is preferable to have a light amount variable function.

The mask used for light irradiation can be appropriately selected from known masks such as a mask having a pattern of openings and a mask having a predetermined light transmittance. In the first aspect, the mask can be appropriately selected from known masks such as a mask provided with openings in a pattern and a mask having a predetermined light transmittance.

In addition, in the method for producing a selective reflection film of the present invention, in addition to the above-mentioned exposure step, a step of appropriately performing an alignment treatment on the contact surface with the cholesteric liquid crystal layer depending on the object and the production mode selected ( Alignment treatment step), a step of transferring the liquid crystal layer by adhesion (lamination) / peeling with a transfer material having a liquid crystal layer (transfer step), a step of forming a liquid crystal layer by applying a cholesteric liquid crystal phase (application step), etc. May be formed.

Taking the case of producing a color filter as an example, for example, the production method of the following aspect (1) or (2) may be used, and the production method can be more suitably produced by these two aspects. <Aspect (1)> (Step 1): A step of producing a transfer material. A liquid crystalline composition (cholesteric liquid crystal composition) in a coating liquid is provided on a temporary support to form a transfer material having at least a cholesteric liquid crystal layer made of the composition. The liquid crystalline composition of the coating liquid can be prepared by dissolving and dispersing each component in an appropriate solvent, and the solvent is, for example, 2-
Butanone, cyclohexanone, methylene chloride, chloroform and the like can be mentioned. A cushion layer containing a thermoplastic resin or the like may be provided between the liquid crystal layer and the temporary support from the viewpoint of ensuring adhesion at the time of transfer such as when foreign matter is present on the transfer target. However, it is also preferable that the surface of the cushion layer or the like is subjected to an alignment treatment such as a rubbing treatment [alignment treatment step].

(Step 2): A layer forming step of transferring and forming a cholesteric liquid crystal layer. The transfer material is laminated on a light-transmissive base material (substrate), and the transfer material is peeled off from the substrate to form a cholesteric liquid crystal layer (transfer step). In addition to the light-transmissive base material,
An image receiving material having an image receiving layer on a substrate may be used. Although the liquid crystal layer may be formed by coating as in the later-described embodiment (2), the transfer method is preferable in terms of material loss and cost. The liquid crystal layer may be composed of a plurality of layers by further laminating after the following (step 3). (Step 3): the exposure step according to the present invention described above. For the cholesteric liquid crystal layer on the base material, a region showing monochromatic selective reflection is formed by irradiating it with light of wavelength λ ¹ , and further irradiating the region with light of wavelength λ ² to the desired selective reflection wavelength. And, it is cured and fixed in a pattern. In addition, regarding each of these steps and the materials such as the transfer material and the base material to be used,
The details are described in the respective specifications of Japanese Patent Application No. 11-342896 and Japanese Patent Application No. 11-343665 previously filed by the present inventors.

<Aspect (2)> (Step 1): A layer forming step of forming a cholesteric liquid crystal layer by coating. The liquid crystal composition is directly applied onto the substrate (support) constituting the color filter to form a cholesteric liquid crystal layer.
The liquid crystal layer can be formed by applying a liquid crystal composition prepared as a coating liquid in the same manner as above by a known coating method using a bar coater, a spin coater or the like. Further, an alignment film similar to the above may be formed between the cholesteric liquid crystal layer and the base material. On the surface of the alignment film or the like,
Alignment treatment such as rubbing treatment [Alignment treatment step]
Is also preferable. (Step 2): An exposure step similar to (Step 3) of the aspect (1).

Hereinafter, as an example of the method of manufacturing the selective reflection film of the present invention, a method of manufacturing the cholesteric liquid crystal color filter according to the aspect B will be described with reference to FIGS. 2 and 3 are schematic process diagrams for explaining processes up to forming a cholesteric liquid crystal layer on a substrate. FIG. 4 is a schematic process diagram for explaining the formation of a multicolor pattern of RGB three colors according to the first aspect. FIG. 5 is a schematic process diagram for explaining a process of forming a monochrome pattern by repeating the process of forming a monochromatic pattern according to the second mode.

First, the components described below are dissolved in an appropriate solvent to prepare a coating liquid cholesteric liquid crystal composition.
As shown in FIG. 2- (A), a temporary support 10 is prepared, and a cushion layer (thermoplastic resin layer) 12 is provided on the temporary support 10 by coating and forming, for example, acrylic resin, polyester, polyurethane or the like. . Furthermore, an alignment film made of polyvinyl alcohol or the like may be laminated, and the alignment film is subjected to a rubbing treatment if necessary (alignment treatment step). The rubbing treatment can improve the orientation. Next, as shown in FIG. 2 (B), a cholesteric liquid crystal composition in a coating liquid is applied on the cushion layer 12 and dried to form a cholesteric liquid crystal layer 16, and then the cholesteric liquid crystal layer 16 is covered. The film 18 is provided to produce a transfer material. Hereinafter, the transfer material is referred to as a transfer sheet 20.

On the other hand, as shown in FIG. 2- (C), another base material 22 is prepared, an alignment film 24 is formed on the base material 22 in the same manner as described above, and the surface thereof is subjected to a rubbing treatment. (Alignment treatment step). Hereinafter, this is referred to as a color filter substrate 26. Then, after peeling off the cover film 18 of the transfer sheet 20, as shown in FIG.
The surface of the cholesteric liquid crystal layer 16 of 0 and the surface of the alignment film 24 of the color filter substrate 26 are superposed so as to be in contact with each other, and laminated through a roll rotating in the arrow direction in the drawing. After that, as shown in FIG. 3- (E), the transfer sheet 20 is peeled off between the cushion layer 12 and the cholesteric liquid crystal layer 16, and the cholesteric liquid crystal layer is transferred onto the color filter substrate (transfer step). In this case, the cushion layer 12 does not necessarily have to be peeled off together with the temporary support 10.

Here, in the cholesteric liquid crystal layer, the cholesteric liquid crystal layer may be preliminarily brought into a state of exhibiting selective reflection of the first color (the above mode B), and by doing so, the light of λ ¹ is irradiated for the first color. The first step after the transfer step can be omitted as shown in FIG.
It is possible to shift to the patterning of the first color and the fixing of the hue as shown in FIG. Note that the wavelength λ ¹
The process of irradiating the above-mentioned light to bring about the state of exhibiting monochromatic selective reflection may be performed (the above-mentioned aspect A).

After the transfer, the three RGB colors can be formed imagewise as follows. That is, as shown in FIG. 4- (F-i), an exposure mask 28 having a plurality of regions having different light transmittances is closely arranged on the cholesteric liquid crystal layer 16, and the exposure mask 28 having the wavelength λ ¹ is arranged through the mask 28. The cholesteric liquid crystal layer 16 may be irradiated with light in a pattern (first mode). After the irradiation, it is heated to a temperature at which a liquid crystal state showing a selective reflection wavelength is formed corresponding to the photoreactive chiral compound isomerized according to the light irradiation amount. Then, FIG. 4- (F-i
As shown in i), the wavelength λ for the cholesteric liquid crystal layer 16 is
It is fixed by irradiating it with the light of ² (ultraviolet rays, etc.), and it is fixed in Fig. 4- (F-
As shown in iii), a BGR reflective region is formed.

Irradiation may be performed as shown in FIG.
Yes. That is, it already shows the selective reflection of the first color (for example, R).
With respect to the cholesteric liquid crystal layer 16 in the state,
Wavelength through the mask 4²Light is emitted like an image
, Only the irradiated area is cured, and the hue of the first color is solid.
It is standardized (for example, R pixels) and patterned (FIG. 5-
(See Fb)). Then, as shown in FIG. 5- (F-b)
Light quantity h^βLight (wavelength λ ¹) Is irradiated on the entire surface,
The entire unfixed area of the cholesteric liquid crystal layer is
A state showing the selective reflection of the second color is formed. This state
Then, a photomask 4'is arranged as shown in FIG.
And the wavelength λ is set through the photomask 4 '.²Image of light
When irradiated, only the irradiated area is cured and
The second hue is fixed (for example, G pixel), and the pattern
(See FIG. 5- (F-d)). Furthermore, Fig. 5- (F-
As shown in d),^γLight (wavelength λ¹) Illuminates the entire surface
When exposed, the cholesteric liquid crystal layer is not immobilized.
A state showing selective reflection of the third color is formed in all areas.
It Here, production of a color filter composed of three colors of RGB
In the case of, the third hue is fixed and the
Selectively pattern the formation of exposed areas (eg, B pixels)
It is not necessary to do this as shown in Figure 5- (F-e).
Long λ²It is sufficient to irradiate the entire surface with this light. In each exposure step
The wavelength of the emitted light λ¹Must have the same wavelength.
It doesn't matter.

Further, if necessary, 2-butanone, chloroform or the like is used to alkali-develop unnecessary portions on the cholesteric liquid crystal layer 16 (for example, remaining portions of the cushion layer, the intermediate layer and the like, unexposed portions). Be removed. As described above, the cholesteric liquid crystal color filter of the present invention having three colors of RGB can be manufactured.

Although the method shown in FIGS. 2 to 5 is one form of the manufacturing method by the laminating method, it may be a manufacturing method by the coating method in which the liquid crystal layer is directly formed by coating on the color filter substrate. In this case, applying the above aspect,
First, after coating and drying a cholesteric liquid crystal layer on the alignment film 24 of the color filter substrate 26 shown in FIG. 2- (C), the same process as in FIG. 4- (F-i) to (F-iii) or FIG. 5-
The processes shown in (Fa) to (Fe) are sequentially performed.

The thickness of the liquid crystal layer (sheet-shaped liquid crystal composition) that functions as a cholesteric liquid crystal color filter is preferably 0.5 to 4 μm. The selective reflection film (for example, a color filter or the like) manufactured by the manufacturing method of the present invention is a liquid crystal composition (cholesteric liquid crystal layer) provided on a substrate, or is composed of only a liquid crystal composition. Any of these may be used.

As described above, the visible light region, preferably 4
Since a liquid crystal composition containing a photoreactive chiral compound having absorption capable of being isomerized at 90 to 570 nm or 630 to 690 nm is used, and light in the vicinity of the absorption wavelength of the chiral compound is imagewise irradiated, the amount of light is small. Without being affected by the change, it is possible to eliminate the nonuniformity of the spiral change (twist change rate) of the liquid crystal due to the change of the light amount due to the uneven irradiation, and prevent the deterioration of the hue purity and the hue uniformity. As a result, a desired hue (particularly green or red) can be stably and uniformly obtained.

<Liquid Crystal Composition> The liquid crystal composition (cholesteric liquid crystal composition) according to the present invention comprises a liquid crystal compound having at least one polymerizable group and a light having isomerizable absorption in the visible light region. It contains at least a reactive chiral compound and a polymerization initiator, preferably contains an air interface aligning agent and a polymerizable monomer, and optionally contains other components such as a binder resin and a polymerization inhibitor. Good.

—Photoreactive Chiral Compound— As the photoreactive chiral compound (hereinafter, may be simply referred to as “chiral compound”), its photosensitivity peak wavelength is a polymerization which will be described later in view of improving patterning sensitivity. Those which are on the longer wavelength side than the photosensitizing peak wavelength of the initiator are preferable, and in the present invention, among them, a photoreactive chiral compound having light absorption capable of photoisomerization in the visible light region (preferably 400 nm or more) is used. contains.

In the above area, blue (B) -green (G) -red
Since a wavelength exhibiting (R) is included, by selecting a chiral compound having light absorption in a desired wavelength range in accordance with the wavelength of a light source used, as shown in FIG. Since it is possible to widen the light amount range a ² corresponding to the steep region of, for example, the light amount range a ³ showing the selective reflection of green, it is possible to stably obtain a desired hue without being affected by a minute change of the light amount (irradiation unevenness, etc.). (Eg green) can be obtained. As a result, it is possible to eliminate the non-uniformity of the spiral change of the liquid crystal due to the change of the light amount due to the uneven irradiation, and prevent the deterioration of the hue purity and the hue uniformity.

The photoreactive chiral compound is a compound capable of changing the helical pitch induced in the liquid crystal composition by light irradiation (visible light), and therefore, as a necessary site (molecular structural unit), a chiral site is used. And a site that undergoes a structural change upon irradiation with light. Those sites are preferably contained in one molecule. In the present invention,
In addition to the above-mentioned photoreactive chiral compound, a chiral compound that does not photoreact, such as a chiral compound having high temperature dependence of twisting property, can be used in combination.

In the present invention, among the compounds having light absorption capable of photoisomerization in the visible light region, the light absorption capable of isomerization is 490 to 570 nm or 630 to 690 nm.
More preferably, the compound in When the isomerizable light absorption is in the range of 490 to 570 nm, the wavelength range coincides with the selective reflection wavelength indicating green, but the liquid crystalline composition accompanying the isomerization of the chiral compound as the light in the wavelength range is irradiated. The helical pitch (twist angle) of the blue light shows a selective reflection from blue to green. At this time, most of the irradiation light is reflected and the amount of light absorbed by the liquid crystalline composition can be reduced. As a result, isomerization occurs slowly, so the light amount range for obtaining green selective reflection can be expanded,
It is possible to eliminate the unevenness of the spiral change of the liquid crystal due to the change of the light amount due to the uneven irradiation. That is, the color purity and hue uniformity of green are improved, and the positional accuracy (color fractionation) of the pattern can also be improved.

On the other hand, the red color that is selectively reflected is liable to have an orange tinge or the display sensitivity tends to be dark if the absorption edge is slightly displaced. The wavelength range of 630 to 690 nm matches the selective reflection wavelength indicating red, but if a chiral compound having an isomerizable light absorption at 630 to 690 nm is used, irradiation with light in the wavelength range causes red light to be emitted. The color purity is improved, and the positional accuracy (color fraction) of the pattern can also be improved.

The photoreactive chiral compound preferably has a large force for inducing a helical structure of the liquid crystal composition. For this purpose, the chiral moiety is located at the center of the molecule,
It is preferable that the surroundings have 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 the chiral site and the site where the structural change due to light irradiation occurs close to each other. Furthermore, a photoreactive chiral compound having high solubility in a liquid crystal compound is preferable, and a compound having a solubility parameter SP value close to that of a liquid crystalline polymerizable monomer is more preferable. Further, when the structure of 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 part that changes its structure by light irradiation include photochromic compounds (Kingo Uchida, Masahiro Irie, Chemical Industry, vol.64, p.640, 1999, Shingo Uchida,
Masahiro Irie, Fine Chemicals, vol. 28 (9),
p.15, 1999) and the like.

The photoreactive chiral compound has at least one absorption wavelength capable of being isomerized by light in the visible light region, preferably longer than 400 nm, and a compound having two or more absorption wavelengths is also suitable. is there. Specific examples are shown below, but the invention is not limited thereto.

[0062]

[Chemical 1]

In the above structural formula, m represents an integer of 1 to 8, preferably an integer of 1 to 3. Moreover, n represents the integer of 1-10, and the integer of 1-5 is preferable.

In the present invention, the photoreactive chiral compound having absorption capable of being isomerized in the visible light region may be used in a combination of two or more kinds, or may be used alone. Further, a known photoreactive chiral compound or non-photoreactive chiral compound can be used in combination with the photoreactive chiral compound.

The content of the photoreactive chiral compound having absorption capable of being isomerized in the visible light region is as follows: "the liquid crystal compound having at least one polymerizable group" is dissolved after uniformly dissolving the photoreactive chiral compound. , Observed at a temperature indicating a liquid crystal state by heating, calculated based on the selective reflection wavelength measured,
It is preferable that the central wavelength of the selective reflection wavelength be 400 nm or less. If this amount is exceeded, orientation deterioration or sensitivity deterioration may occur. In addition, the HTP difference (Δ) of the twisting force of the photoreactive chiral compound before and after the light irradiation changes with the light irradiation.
It is preferable that the amount obtained by multiplying HTP) by the weight percentage is 1.07 or more. If the amount is less than this amount, it may be difficult to perform multicolor patterning with a wide hue width (that is, a wide wavelength region for selective reflection). Here, HTP refers to the helical pitch of liquid crystal that changes with irradiation of light, that is, the twisting power of the helical structure (helical twisting power), and the difference (ΔHTP) changes before and after irradiation with light. The difference in the spiral pitch.

-Liquid crystalline compound having at least one polymerizable group-The liquid crystalline compound having at least one polymerizable group (in the present specification, may be simply referred to as "liquid crystalline compound") is polymerizable. It can be appropriately selected from known liquid crystal compounds having a group, and among them, rod-shaped nematic liquid crystal compounds (hereinafter, simply referred to as “nematic liquid crystal compounds”) are preferable.

The nematic liquid crystal compound can be appropriately selected from liquid crystal compounds having a refractive index anisotropy Δn of 0.10 to 0.40, polymer liquid crystal compounds and polymerizable liquid crystal compounds. A cholesteric liquid crystal composition can be obtained by using a photoreactive chiral compound in combination with a nematic liquid crystal compound. In addition, the nematic liquid crystal compound can be aligned while being in a liquid crystal state when melted, for example, by using an alignment substrate that has been subjected to an alignment treatment such as a rubbing treatment. Further, when the liquid crystal state is changed to a solid phase and immobilized, means such as cooling and polymerization can be used. That is, since the liquid crystal compound has a polymerizable group and its reactivity is extremely high, a tough film can be formed by efficiently polymerizing the compound in the aligned state.

Among the nematic liquid crystal compounds, for example, a liquid crystal compound in which a UV-curable functional group (for example, an acrylate group) which polymerizes and cures in response to ultraviolet rays is introduced in the same molecule is preferable. When this is irradiated with ultraviolet rays to be solidified, a color filter having high film strength can be produced at a low temperature of 120 ° C. or lower.

The following compounds may be mentioned as specific examples of the nematic liquid crystal compound. However, the present invention is not limited to these.

[0070]

[Chemical 2]

[0071]

[Chemical 3]

[0072]

[Chemical 4]

In the above formula, n represents an integer of 1 to 1000. In each of the above-exemplified compounds, those in which the side chain connecting group of the aromatic ring is changed to the following structures can also be mentioned as suitable examples.

[0074]

[Chemical 5]

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

The liquid crystal compounds may be used alone or in combination of two or more. A liquid crystal compound having no polymerizable group may be used in combination with the "liquid crystal compound having at least one polymerizable group". The content of the "liquid crystal compound having at least one polymerizable group" is preferably 30 to 98 mass% with respect to the total solid content (mass) of the liquid crystal composition (cholesteric liquid crystal composition), and 50 ˜95% by mass is more preferred. The content is 3
If it is less than 0% by mass, the orientation may be insufficient and the desired selective reflection color may not be obtained.

—Polymerization Initiator— The polymerization initiator accelerates a polymerization reaction based on an unsaturated bond, polymerizes and cures the liquid crystalline composition to immobilize it, and enhances the strength of the liquid crystalline composition after immobilization. To improve more. The polymerization initiator can be appropriately selected from known compounds such as photoreactivity and heat reactivity, and among them, a photopolymerization initiator capable of promoting the reaction by light irradiation is preferable. For example, a polymerization and curing reaction of a cholesteric liquid crystal composition or the like can be rapidly performed, and a large intrinsic birefringence (Δn), high resolution, and selective reflection color with high color purity can be stably obtained.

The photopolymerization initiator can be appropriately selected from known ones, for example, p-methoxyphenyl-2,4-bis (trichloromethyl) -s-triazine and 2- (p-butoxy). Styryl) -5-trichloromethyl 1,3,4-oxadiazole, 9-phenylacridine, 9,10-dimethylbenzphenazine,
Examples thereof include benzophenone / Michler's ketone, hexaarylbiimidazole / mercaptobenzimidazole, benzyldimethylketal, thioxanthone / amine and the like.

The amount of the polymerization initiator added is preferably 0.1 to 20% by mass and more preferably 0.5 to 5% by mass based on the solid content (mass) of the liquid crystalline composition. The amount added is
If it is less than 0.1% by mass, it may take a long time because the curing efficiency is low, and if it exceeds 20% by mass, for example, in the case of a photopolymerization initiator, the light transmittance from the ultraviolet region to the visible light region is increased. It may be inferior.

—Air Interface Orientation Agent— The air interface orientation agent is a surfactant having an excluded volume effect. Here, having an excluded volume effect means controlling the orientation of liquid crystal (molecule) on the air interface side, that is, when forming a layer containing a liquid crystalline composition by coating, for example, liquid crystal at the air interface on the surface of the layer. The three-dimensional control of the spatial orientation state of. Specifically, it means controlling the pretilt angle of liquid crystal molecules on the air interface side.

The molecular structural requirements of the preferred air interface aligning agent include a flexible hydrophobic portion and a molecularly rigid unit (hereinafter referred to as a rigid portion) having one or more cyclic units. That is. Depending on the type of liquid crystal compound used, the flexible hydrophobic site may be a perfluoro chain or a long alkyl chain. Since the hydrophobic portion is flexible, the hydrophobic portion can be effectively arranged on the air side. Further, the air interface aligning agent may be a short molecule having a number of molecules of about several hundreds, or may be a polymer or oligomer in which they are linked. It is also possible to add a polymerizable functional group depending on the purpose.

When such an air interface aligning agent is contained, the flexible hydrophobic portion of the air interface aligning agent exists in the air interface direction, and the rigid portion exists in the liquid crystal molecule direction. Is planar and is arranged in parallel with the air interface, it is possible to arrange the liquid crystal molecules in parallel with the air interface. On the other hand, if the rigid portion is aligned vertically with the air interface, the liquid crystal molecules can be aligned vertically with the air interface. Specifically, nonionic surfactants are preferable, and the following compounds are preferable.

[0083]

[Chemical 6]

[0084]

[Chemical 7]

The amount of the air interface aligning agent added is preferably such that the surface of the layer containing the liquid crystal composition on the air interface side is covered by about one molecule, based on the total solid content (mass) of the liquid crystal composition. , 0.05 to 5 mass% is preferable, and 0.1 to 1.
0 mass% is more preferable. If the addition amount is less than 0.05% by mass, the effect may not be exhibited.
When the content is more than mass%, the air interface aligning agent itself may associate with each other to cause phase separation with the liquid crystal. The surface tension can be reduced by containing the air interface aligning agent, but a surfactant other than the air interface aligning agent may be used in combination for the purpose of further reducing the surface tension and improving the coating property. You can also

Further, the surfactant can stereoscopically control the alignment state of liquid crystal molecules at the air interface on the surface of the layer, for example, in the case of applying a coating liquid crystalline composition to form a layer, in particular, a cholesteric liquid crystal. In this case, a selective reflection wavelength with higher color purity can be obtained.

-Polymerizable Monomer- A polymerizable monomer may be used in combination with the liquid crystal composition.
When the polymerizable monomer is used in combination, after patterning (in the case of a cholesteric liquid crystal, the twisting force of the liquid crystal is changed by light irradiation to form a distribution of selective reflection wavelengths), the helical structure (selective reflection) is fixed, The strength of the liquid crystal layer (liquid crystal composition) after fixation can be further improved. However, when the nematic liquid crystal compound has an unsaturated bond in the same molecule, it is not always necessary to add it.

Examples of the polymerizable monomer include monomers having an ethylenically unsaturated bond and the like, and specific examples include polyfunctional monomers such as pentaerythritol tetraacrylate and dipentaerythritol hexaacrylate. Specific examples of the monomer having an ethylenically unsaturated bond include the compounds shown below, but the present invention is not limited thereto.

[0089]

[Chemical 8]

The amount of the polymerizable monomer added is preferably 0.5 to 50 mass% of the total solid content (mass) of the liquid crystal composition. If the addition amount is less than 0.5% by mass, sufficient curability may not be obtained, and if it exceeds 50% by mass, alignment of liquid crystal molecules may be hindered and sufficient color development may not be obtained. Sometimes.

-Other components-In addition, as other components, a binder resin, a polymerization inhibitor,
It is also possible to add a solvent, a thickener, a dye, a pigment, an ultraviolet absorber, a gelling agent and the like. As the other components, those having excellent compatibility with the liquid crystal compound are preferable because they influence the strength of the color filter film cured by ultraviolet curing.

Further, if these components are movable in the cured color filter film, the liberated components reduce the film strength and change the various characteristics of the color filter. Therefore, as the other component to be added, it is preferable to use a component having a functional group of the same type as the polymerizable functional group introduced into the liquid crystal compound. That is, since other components are not liberated in the film and fixed in the liquid crystal compound by polymerization and curing, the film strength and various properties are not impaired. Further, the content of the other components excluding the binder resin and the surfactant is preferably 10% by mass or less of the total solid content (mass) of the liquid crystal composition. When the content exceeds 10% by mass, the strength of the optical film (selective reflection film) may be reduced.

Examples of the binder resin include polystyrene compounds such as polystyrene and poly-α-methylstyrene, cellulose resins such as methyl cellulose, ethyl cellulose and acetyl cellulose, acidic cellulose derivatives having a carboxyl group in the side chain, polyvinyl formal, and the like. Acetal resins such as polyvinyl butyral, JP-A-59-44615, JP-B-54-34327,
JP-B-58-12577, JP-B-54-25957
JP-A-59-53836, JP-A-59-7104
Examples thereof include the methacrylic acid copolymer, acrylic acid copolymer, itaconic acid copolymer, crotonic acid copolymer, maleic acid copolymer, and partially esterified maleic acid copolymer described in No. 8. Moreover, the homopolymer of acrylic acid alkyl ester and the homopolymer of methacrylic acid alkyl ester are also mentioned, About these, especially an alkyl group is a methyl group, an ethyl group, n-propyl group, n-butyl group, iso-butyl group. , N-hexyl group, cyclohexyl group, 2-ethylhexyl group and the like are preferable. In addition, polymers obtained by adding an acid anhydride to a polymer having a hydroxyl group, benzyl (meth) acrylate / (methacrylic acid homopolymer) acrylic acid copolymer, and benzyl (meth) acrylate / (meth) acrylic acid / other monomers And the like.

Among the above, a binder resin containing a carboxyl group is preferable from the viewpoints of alkali developability after patterning and mass productivity. When forming (coating, transferring, etc.) a liquid crystal layer on a plastic substrate, if a binder resin containing a carboxyl group is used as a binder component in a cholesteric liquid crystal composition prepared as a coating liquid,
Alkali development is possible, and patterning can be easily performed by alkali development after light irradiation.

The content of the binder resin in the liquid crystal composition is preferably 0 to 50% by mass, and 0 to 30% by mass.
Mass% is more preferable. If the content exceeds 50% by mass, the liquid crystal compound may be insufficiently aligned.

The polymerization inhibitor may be added for the purpose of improving storage stability. Examples thereof include hydroquinone, hydroquinone monomethyl ether, phenothiazine, benzoquinone, and derivatives thereof. The amount of the polymerization inhibitor added is 0 to 1 with respect to the polymerizable monomer.
0 mass% is preferable, and 0-5 mass% is more preferable.

The liquid crystal composition can be prepared by dissolving and dispersing each of the above-mentioned components in a solvent (in the form of coating liquid), molding this into an arbitrary shape, or forming it on a support or the like (preferably, for example, for example, It can be used by forming a liquid crystal composition layer by coating). When the liquid crystal composition layer is formed by coating, a layer having a uniform layer thickness and surface properties can be obtained, and a selective reflection film having excellent optical characteristics can be formed. Examples of the solvent include 2-butanone, cyclohexanone, methylene chloride, chloroform and the like.

<Selective Reflective Film> The selective reflective film of the present invention can be suitably produced by the above-described method of producing the selective reflective film of the present invention. More preferably, 490 to 570 nm
Alternatively, a liquid crystal composition having absorption capable of being isomerized in the wavelength region of 630 to 690 nm has the same direction as the twist direction of the spiral of the liquid crystal and has a wavelength of 490 to 570 nm or 63
It can be produced by irradiating circularly polarized light or elliptically polarized light of 0 to 690 nm imagewise and patterning.

Therefore, the selective reflection film of the present invention effectively suppresses the occurrence of color unevenness during patterning due to the unevenness even when the coating thickness is uneven. Excellent hue uniformity (particularly, green or red hue and its uniformity).

The form of the final selective reflection film is not particularly limited, and it is in the form of a sheet composed only of the above liquid crystalline composition, or a layer containing the liquid crystalline composition on a desired support or temporary support ( A liquid crystal layer) may be provided, and other layers (films) such as an alignment film and a protective film may be further provided.

In the case where a layer containing a liquid crystalline composition (liquid crystal layer) is provided on a desired support or temporary support, the liquid crystal layer includes a liquid crystal compound (nematic liquid crystal compound) and a photoreactive chiral compound. And a polymerization initiator, each of which comprises at least one type of cholesteric liquid crystal composition, and may further contain other components such as a polymerizable monomer, a surfactant and a binder resin, if necessary. In the present invention, it is particularly preferable to use an air interface aligning agent and a polymerizable monomer in combination. By including the air interface aligning agent, as described above,
A selective reflection wavelength having particularly high color purity can be obtained.

As described above, since the cholesteric liquid crystal composition is used, it is a non-light-absorption type selective reflection film, and exhibits various hues in which the wavelength range of selective reflection of liquid crystal is wide, and the color purity (especially green, Red) and its uniformity, and a selective reflection film that is particularly excellent in resolution. For example, it is a high-resolution color that is composed of primary colors (B, G, R) with high color purity and has high patterning accuracy and good color separation. It can be a filter.

The selective reflection film of the present invention is used for a display device such as an LCD in addition to a (laminated) color filter.
Retardation film, circularly polarized light reflector, brightness enhancement film for transmissive LCDs, optical parts used for projectors such as color wheels, painted ornaments, high-gloss (metallic) printed matter, anti-counterfeit display It can be preferably used for

[0104]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Example 1 (1) Preparation of Filter Substrate A polyimide alignment film (LX-1400, manufactured by Hitachi Chemical DuPont Co., Ltd.) coating solution was applied on a glass substrate by a spin coater and dried in an oven at 100 ° C. for 5 minutes. After 2
An alignment film was formed by baking in an oven at 50 ° C. for 1 hour.
Further, the surface of the film was subjected to orientation treatment by rubbing treatment to produce a glass substrate with an orientation film.

(2) Formation of Filter Layer A coating liquid (1) for a photosensitive liquid crystal layer prepared by the following formulation was applied onto the alignment film of the glass substrate with an alignment film obtained above by a spin coater, and In an oven at 100 ° C for 2
After drying for a minute, a photosensitive liquid crystal layer (liquid crystal composition layer) was formed (layer forming step). When the layer thickness was measured by a confocal microscope, it was 2.3 μm.

[0106]

[Chemical 9]

Then, the glass substrate having the photosensitive liquid crystal layer formed thereon is brought into contact with the surface of the glass substrate at 100 ° C.
The film was kept on the hot plate for 3 minutes to align (color) the photosensitive liquid crystal layer. At this time, the photosensitive liquid crystal layer became a liquid crystal phase and exhibited selective reflection with a center wavelength of 450 nm (blue formation). Subsequently, in the state of being held at 80 ° C., the opening has a line width of 80 μm and an opening pitch of 27 with respect to the photosensitive liquid crystal layer.
Striped photomask of 0 μm, interference filter having transmission center wavelength at 530 nm, polarizing plate, λ / 4
Xenon light (λ ¹ ) was irradiated through the plate (left circularly polarized light) for 10 seconds (irradiation intensity 5 mW / cm ² ) to perform patterning. At this time (80 ° C.), the light-irradiated portion of the photosensitive liquid crystal layer showed green selective reflection. While maintaining at 80 ° C., the photomask is moved 90 μm in the line width direction,
Irradiation (λ ¹ ; irradiation intensity 40 mW / cm ² ) was conducted for 5 seconds in the same manner as above through the photomask and the interference filter, and patterning was performed. Then, the light-irradiated part of the photosensitive liquid crystal layer showed red selective reflection (80 ° C.). The unirradiated portion of the photosensitive liquid crystal layer showed blue selective reflection (alignment step).
From the above, the photosensitive liquid crystal layer has blue (B), green (G), and red
A pattern showing selective reflection was formed on (R).

Next, this glass substrate was held on a hot plate at 60 ° C., and irradiated with a super high pressure mercury lamp for 5 seconds (λ ² ; irradiation intensity) through an interference filter having a transmission center wavelength at 313 nm under a nitrogen atmosphere. 100 mW / c
m ² ) was carried out to polymerize and cure the photosensitive liquid crystal layer. Further, for the purpose of accelerating the curing of the film, heat treatment was performed at 250 ° C. for 15 minutes to obtain a color filter according to the present invention.

The center wavelengths of the B, G and R selective reflections of the obtained color filter are 440 nm and 53, respectively.
It was 0 nm and 650 nm, and a hue with high color purity was obtained in each color. Moreover, in each color, the variation in the central wavelength of the selective reflection between the pixels in the color filter is within ± 2 nm, which is also excellent in the hue uniformity.

(Example 2) A glass substrate with an alignment film as a filter substrate was prepared in the same manner as in Example 1, and instead of the photosensitive liquid crystal layer coating solution (1) used in Example 1, the following was used. A photosensitive liquid crystal layer was formed on the alignment film in the same manner as in Example 1 except that the coating liquid (2) for the photosensitive liquid crystal layer having the formulation was used (layer forming step). When the layer thickness was measured by a confocal microscope, it was 2.3 μm.

[0111]

[Chemical 10]

Then, as in Example 1, the glass substrate on which the photosensitive liquid crystal layer was formed was held on a hot plate at 100 ° C. for 3 minutes to align (color develop) the photosensitive liquid crystal layer. At this time, the photosensitive liquid crystal layer becomes a liquid crystal phase and the central wavelength 455
It showed selective reflection of nm (blue formation). Then, 80 ℃
In the same manner as in Example 1 with the photosensitive liquid crystal layer held in place (a photomask, an interference filter having a transmission center wavelength at 530 nm, a polarizing plate, and a λ / 4 plate (left circularly polarized light)).
And was irradiated with xenon light (λ ¹ ) for 20 seconds (irradiation intensity 5 mW / cm ² ). At this time (80 ° C.), the light-irradiated portion of the photosensitive liquid crystal layer showed green selective reflection. Then, while maintaining at 80 ° C., irradiation was performed for 10 seconds (λ by the same manner as in Example 1 (through a photomask and an interference filter)).
¹ ; irradiation intensity was 40 mW / cm ² ). At this time (80
C.), and the light-irradiated part of the photosensitive liquid crystal layer showed red selective reflection. The unirradiated portion of the photosensitive liquid crystal layer showed blue selective reflection (alignment step). From the above, the photosensitive liquid crystal layer is blue
A pattern showing selective reflection was formed in (B), green (G), and red (R).

Then, in the same manner as in Example 1, the photosensitive liquid crystal layer was polymerized and cured by irradiation (λ ² ) with an ultra-high pressure mercury lamp for 5 seconds, and further heat-treated at 250 ° C. for 15 minutes,
A color filter according to the present invention was obtained. The central wavelengths of the obtained color filters showing the selective reflection of B, G and R are
It was 445 nm, 532 nm, and 655 nm, respectively, and a hue with high color purity was obtained in each color. Moreover, in each color, the variation in the central wavelength of the selective reflection between the pixels in the color filter is within ± 2 nm, which is also excellent in the hue uniformity.

[0114]

EFFECTS OF THE INVENTION According to the present invention, it is possible to perform a simple and favorable alignment treatment, avoid a decrease in color purity and resolution due to a hue shift due to uneven irradiation, and the like. In particular, it is possible to provide a method for producing a selective reflection film which can obtain green or red and can perform color separation (patterning) with high accuracy. In addition, a selective reflection film having excellent hue and hue uniformity for selective reflection, particularly green or red hue and its uniformity, high resolution and color fractionation (patterning accuracy), and good optical characteristics is provided. Can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the amount of light irradiated to a photoreactive liquid crystalline composition and the selective reflection wavelength.

FIG. 2 is a schematic process drawing for explaining processes up to forming a cholesteric liquid crystal layer on a substrate.

FIG. 3 is a schematic process drawing for explaining processes up to forming a cholesteric liquid crystal layer on a substrate.

FIG. 4 is a schematic view showing that a multicolor pattern of RGB three colors is formed according to the first aspect in the method for producing a selective reflection film of the present invention.

FIG. 5 is a schematic process diagram for explaining that, in the method for producing a selective reflection film of the present invention, the steps of forming a single color pattern according to the second aspect are repeated to form RGB three colors in an imagewise manner. .

[Explanation of symbols]

4,4 '... Photo mask 10 ... Temporary support 12 ... Cushion layer (thermoplastic resin layer) 24 ... Alignment film 16 ... Cholesteric liquid crystal layer (phase) 20 ... Transfer sheet 22 ... Base material (support) 26 ... Color filter substrate 28 ... Mask

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/1335 510 G02F 1/1335 510 F term (reference) 2H048 BA04 BA64 BB02 BB42 2H049 BA03 BA04 BA18 BA43 BB01 BC05 BC08 BC22 2H088 EA47 EA49 GA02 GA03 GA17 HA12 HA16 HA18 HA21 KA04 KA06 MA04 MA20 2H091 FA02Y FA07Y KA10 LA15 LA18

Claims (8)

[Claims] 1. A liquid crystal composition comprising a liquid crystal compound having at least one polymerizable group, a photoreactive chiral compound having absorption capable of isomerizing in the visible light region, and a polymerization initiator in an image manner. A method for producing a selective reflection film, which comprises irradiating light (wavelength λ ¹ ) to form a pattern exhibiting selective reflection according to the irradiation, wherein the light irradiation is circularly polarized light and elliptical light in the same direction as the twist direction of the liquid crystal spiral. A method of manufacturing a selective reflection film, which uses one of polarized light. 2. The liquid crystal composition is irradiated with light having a wavelength of λ ¹ to form an exposure dose distribution in the liquid crystal composition, and the liquid crystal composition is brought into a state of exhibiting selective reflection according to the exposure dose distribution, Irradiating the liquid crystalline composition in the state with light of wavelength λ ² to polymerize and cure in an imagewise manner to form a multicolor pattern, wherein the light of wavelength λ ¹ is in the same direction as the twist direction of the spiral of the liquid crystal. The method for producing a selective reflection film according to claim 1, wherein the selective reflection film has either circularly polarized light or elliptically polarized light. 3. The liquid crystal composition is imagewise irradiated with light having a wavelength of λ ¹ to bring about a state of selective reflection in response to the irradiation,
At least one step of forming a monochromatic pattern by further irradiating the region of this state with light of wavelength λ ² to polymerize and cure in an imagewise manner, wherein the light of wavelength λ ¹ is in the same direction as the twist direction of the liquid crystal helix. The method for producing a selective reflection film according to claim 1, wherein the selective reflection film is either circularly polarized light or elliptically polarized light. 4. A liquid crystal composition in the state of exhibiting selective reflection of the first color is irradiated with light having a wavelength of λ ² to polymerize and cure in an imagewise manner to form a monochromatic pattern, and then the first color. By changing the irradiation amount of the light having the wavelength λ ¹ to (n-1) steps so as to show selective reflection of a different wavelength from (n-1) times and repeating the step of forming a monochromatic pattern, The method for producing a selective reflection film according to claim 3, wherein the multicolor pattern is formed. 5. The photoreactive chiral compound is 490 to 57.
It has absorption capable of isomerization in the wavelength region of 0 nm or 630 to 690 nm, and the light of wavelength λ ¹ has wavelengths of 490 to 5
The method for producing a selective reflection film according to claim 1, wherein the light has a wavelength of 70 nm or 630 to 690 nm. 6. The absorption wavelength λ (nm) capable of being isomerized by the photoreactive chiral compound has a wavelength λ ¹ (nm) of (λ-5).
The method for producing a selective reflection film according to claim ^{1, wherein} 0) ≦ λ ¹ ≦ (λ + 50) is satisfied. 7. The method for producing a selective reflection film according to claim 1, wherein the liquid crystalline composition contains an air interface aligning agent. 8. A selective reflection film obtained by the method for producing a selective reflection film according to any one of claims 1 to 7.