CN110691998B

CN110691998B - Method for producing liquid crystal film and method for producing functional film

Info

Publication number: CN110691998B
Application number: CN201880035113.1A
Authority: CN
Inventors: 长谷川昌孝; 长野论史; 稻田宽; 二村惠朗
Original assignee: Fujifilm Corp
Current assignee: Fujifilm Corp
Priority date: 2017-06-13
Filing date: 2018-06-05
Publication date: 2021-11-16
Anticipated expiration: 2038-06-05
Also published as: WO2018230395A1; JPWO2018230395A1; CN110691998A; JP6924832B2; KR102285177B1; KR20190138692A

Abstract

The invention provides a method for producing a liquid crystal film and a method for producing a functional film, which can obtain a cholesteric liquid crystal layer capable of displaying an image of a fine and desired color gradation and have high productivity. The method for manufacturing a liquid crystal film of the present invention comprises the following steps in order: a coating step of coating a liquid crystal composition containing a cholesteric liquid crystal compound and a photosensitive chiral reagent on the surface of a support while conveying the support in the longitudinal direction; an irradiation step of irradiating the coating film of the liquid crystal composition in an undried state with light of a wavelength to which the chiral agent is sensitive; an alignment step of heating the coating film to align the liquid crystal; and a curing step of curing the oriented coating film, wherein in the irradiation step, the coating film is irradiated with light through a pattern mask arranged on the support side, the pattern mask is a multi-tone pattern mask having 3 or more regions with different transmittances of light of wavelengths to which the hand reagent is exposed, and in the irradiation step, the coating film is irradiated with light through the multi-tone pattern mask, thereby irradiating the regions of the coating film with light of different irradiation amounts.

Description

Method for producing liquid crystal film and method for producing functional film

Technical Field

The present invention relates to a method for manufacturing a liquid crystal film and a method for manufacturing a functional film.

Background

A layer including a cholesteric liquid crystal phase (cholesteric liquid crystal layer) is known as a layer having a property of selectively reflecting either right-handed circularly polarized light or left-handed circularly polarized light in a specific wavelength region (selective reflection wavelength band). Therefore, the cholesteric liquid crystal layer can display an image of a color corresponding to a selected reflection wavelength by reflecting the light, and is developed for various applications.

For example, patent document 1 describes a configuration in which a region having a selective reflection wavelength band different from other regions is provided at least at one position in a single cholesteric liquid crystal layer, and describes recording authentication information using characteristics of cholesteric liquid crystal.

Patent document 1 describes a method for forming a cholesteric liquid crystal layer having regions with different selective reflection wavelength bands, the method including: a patterned cholesteric liquid crystal layer having a selective reflection wavelength is formed by ultraviolet exposure through a patterned mask.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open No. 2006-142699

Disclosure of Invention

Technical problem to be solved by the invention

However, in the method for forming a cholesteric liquid crystal layer described in patent document 1, when a coating liquid of cholesteric liquid crystal is applied onto a substrate and dried, and then the coating film is irradiated with ultraviolet light to be cured, exposure is performed using a pattern mask. As the pattern mask, only a binary pattern mask having a light shielding portion and a light transmitting portion is described.

As a result of the studies by the present inventors, it has been found that the cholesteric liquid crystal layer formed by such a method has a desired selective reflection wavelength, that is, cannot have a desired color tone, or cannot have sufficient fineness because the boundary between regions having different selective reflection wavelength bands is blurred. In addition, when a binary pattern mask is used, it is necessary to change the pattern mask and perform multiple exposures when 3 or more types of regions having different selective reflection wavelengths are formed in the cholesteric liquid crystal layer. Therefore, the following problems are known: to form a more multicolored cholesteric liquid crystal layer requires many processing steps and is inefficient to manufacture.

In view of the above, an object of the present invention is to provide a method for producing a liquid crystal film and a method for producing a functional film, which can obtain a cholesteric liquid crystal layer capable of displaying an image of a fine and desired color gradation and which have high productivity.

Means for solving the technical problem

As a result of intensive studies on the problems of the prior art, the present inventors have found that the above problems can be solved by a method comprising the following steps: a conveying step of conveying the long support body in a longitudinal direction; a coating step of coating a liquid crystal composition containing a cholesteric liquid crystal compound and a photosensitive chiral reagent on the surface of a support while conveying the conveyed support in the longitudinal direction; an irradiation step of irradiating the coating film of the liquid crystal composition in an undried state with light having a wavelength to which the chiral agent is sensitive; an alignment step of heating the coating film to align the liquid crystal; and a curing step of curing the oriented coating film, wherein in the irradiation step, the coating film is irradiated with light through a pattern mask arranged on the support side, the pattern mask is a multi-tone pattern mask having 3 or more regions with different transmittances of light of wavelengths to which the hand reagent is exposed, and in the irradiation step, the coating film is irradiated with light through the multi-tone pattern mask, thereby irradiating the regions of the coating film with light of different irradiation amounts.

That is, it has been found that the above object can be achieved by the following configuration.

(1) A method for manufacturing a liquid crystal film, comprising the steps of:

a conveying step of conveying the long support body in a longitudinal direction;

a coating step of coating a liquid crystal composition containing a cholesteric liquid crystal compound and a photosensitive chiral reagent on the surface of a support while conveying the conveyed support in the longitudinal direction;

an irradiation step of irradiating the coating film of the liquid crystal composition in an undried state with light of a wavelength to which the chiral agent is sensitive;

an alignment step of heating the coating film to align the liquid crystal; and

a curing step of curing the oriented coating film,

in the irradiation step, the coating film is irradiated with light through a pattern mask disposed on the support side,

the pattern mask is a multi-tone pattern mask having 3 or more regions having different transmittances of light of wavelengths to which the chiral agent is exposed,

in the irradiation step, the coating film is irradiated with light through the multi-tone pattern mask, whereby different irradiation amounts of light are irradiated to the respective regions of the coating film.

(2) The method for producing a liquid crystal film according to (1), wherein,

the pattern mask is formed on the back surface of the support.

(3) The method for producing a liquid crystal film according to (1), wherein,

the pattern mask is formed on the surface of the long substrate film,

in the irradiation step, irradiation with light is performed in a state where the base film on which the pattern mask is formed is attached to the back surface of the support.

(4) The method for producing a liquid crystal film according to any one of (1) to (3),

the pattern mask is formed by gray scale printing.

(5) The method for producing a liquid crystal film according to any one of (1) to (4),

the irradiation step has a first irradiation step and a second irradiation step,

the irradiation amount of light in the first irradiation step is smaller than the irradiation amount of light in the second irradiation step.

(6) The method for producing a liquid crystal film according to (5), wherein,

the total dose of the first irradiation step and the second irradiation step was 200mJ/cm²The following.

(7) The method for producing a liquid crystal film according to any one of (1) to (6),

the peak wavelength of the light irradiated in the first irradiation step and the peak wavelength of the light irradiated in the second irradiation step are different from each other.

(8) The method for producing a liquid crystal film according to any one of (1) to (7),

the curing step is a step of photocuring the coating film,

the wavelength of the light irradiated in the curing step is different from the wavelength of the light irradiated in the irradiating step.

(9) The method for producing a liquid crystal film according to (8), wherein,

in the curing step, the pattern mask is integrally conveyed in a state of being disposed on the back side of the support,

light is irradiated to the surface side opposite to the pattern mask.

(10) The method for producing a liquid crystal film according to any one of (1) to (9),

the method of applying the liquid crystal composition in the application step is bar coating.

(11) The method for producing a liquid crystal film according to any one of (1) to (10), wherein,

repeating the combination of the coating step, the irradiation step, the alignment step and the curing step 2 or more times to form 2 or more cholesteric liquid crystal layers,

in the 2 or more irradiation steps, light is irradiated through the pattern mask having the same pattern, and the irradiation amounts of light in the respective irradiation steps are made different from each other.

(12) A method for producing a functional film, which comprises a step of attaching a circularly polarizing plate to the surface of a cured coating film or the back surface of the support after the curing step of the method for producing a liquid crystal film according to any one of (1) to (11).

Effects of the invention

According to the present invention, a method for producing a liquid crystal film and a method for producing a functional film, which can obtain a cholesteric liquid crystal layer capable of displaying an image of a fine and desired color gradation and have high productivity, can be provided.

Drawings

Fig. 1 is a diagram schematically showing a manufacturing apparatus for carrying out an example of the method for manufacturing a liquid crystal film according to the present invention.

Fig. 2 is a schematic diagram for explaining an example of a method for manufacturing a liquid crystal film by the manufacturing apparatus of fig. 1.

FIG. 3 is a view schematically showing a manufacturing apparatus for carrying out another example of the method for manufacturing a liquid crystal film of the present invention.

Fig. 4 is a schematic cross-sectional view for explaining an example of a method for manufacturing a liquid crystal film by the manufacturing apparatus of fig. 3.

Fig. 5 is a schematic cross-sectional view for explaining an example of a method for manufacturing a liquid crystal film by the manufacturing apparatus of fig. 3.

FIG. 6 is a diagram showing a pattern mask used in the examples.

FIG. 7 is a view showing a liquid crystal film produced in example.

Fig. 8 is a diagram showing another example of the pattern mask used in the present invention.

Fig. 9 is a diagram showing a binary pattern mask used in the comparative example.

Fig. 10 is a diagram showing an example of a pattern mask used in the manufacturing method of the present invention.

Fig. 11 is a view showing a liquid crystal film produced by using the pattern mask shown in fig. 10.

Detailed Description

Hereinafter, the method for producing a liquid crystal film of the present invention will be described in detail. In the present specification, the numerical range expressed by the term "to" means a range including the numerical values described before and after the term "to" as the lower limit value and the upper limit value.

In the present specification, "orthogonal" and "parallel" mean ranges including errors that are allowable in the technical field to which the present invention pertains. For example, "orthogonal" and "parallel" mean that the error with respect to strict orthogonality or parallelism is preferably 5 ° or less, more preferably 3 ° or less, such as the case where the error with respect to strict orthogonality or parallelism is within a range of less than ± 10 °.

In addition, the specific angle other than the angles "orthogonal" and "parallel", for example, 15 ° or 45 °, also includes the range of the error allowable in the technical field to which the present invention pertains. For example, in the present invention, the angle means a case where the angle is less than ± 5 ° from the strict angle specifically expressed, and the error with respect to the strict angle expressed is preferably ± 3 ° or less, and more preferably ± 1 ° or less.

In the present specification, "(meth) acrylate" is used in the meaning of "either one or both of acrylate and methacrylate".

In the present specification, "the same" is intended to include an error range which is generally allowed in the technical field. In the present specification, the term "total", "arbitrary" or "entire" includes not only 100% but also an error range generally allowed in the technical field, and is set to include, for example, 99% or more, 95% or more, or 90% or more.

The visible light is light of a wavelength visible to the human eye among electromagnetic waves, and represents light in a wavelength range of 380nm to 780 nm. Non-visible light is light in a wavelength region of less than 380nm or a wavelength region of more than 780 nm.

In the visible light, light in the wavelength region of 420nm to 490nm is blue light, light in the wavelength region of 495nm to 570nm is green light, and light in the wavelength region of 620nm to 750nm is red light.

Among infrared light, near-infrared light is electromagnetic waves in a wavelength range of 780nm to 2500 nm. The ultraviolet light has a wavelength of 10-380 nm.

In the present specification, the selective reflection wavelength means that when Tmin (%) is taken as the minimum value of the transmittance of an object (member), the half-value transmittance represented by the following formula is expressed: average of 2 wavelengths of T1/2 (%).

Equation for half value transmission: t1/2 ═ 100- (100-Tmin) ÷ 2

In the present specification, "haze" refers to a value measured using a haze meter NDH-2000 manufactured by NIPPON DENSHOKU indtrials co.

Theoretically, the haze means a value represented by the following formula.

(scattering transmittance of natural light of 380-780 nm)/(scattering transmittance of natural light of 380-780 nm + direct transmittance of natural light) x 100%

The scattering transmittance is a value that can be calculated by subtracting the direct transmittance from the obtained omnidirectional transmittance using a spectrophotometer and an integrating sphere unit. The direct transmittance is a transmittance at 0 ° based on a value measured by an integrating sphere unit. That is, low haze means that the amount of straight transmitted light is large among the total amount of transmitted light.

The refractive index is a refractive index with respect to light having a wavelength of 589.3 nm.

In the present specification, Re (λ) and Rth (λ) represent in-plane retardation and thickness-direction retardation, respectively, at a wavelength λ. The wavelength λ is set to 550nm unless otherwise specified.

In the present specification, Re (λ), Rth (λ) are values measured from a wavelength λ in AxoScan OPMF-1(Opto Science, inc.). The following was calculated by using the AxoScan input average refractive index ((Nx + Ny + Nz)/3) and film thickness (d (μm)):

slow axis direction (°)

Re(λ)＝R0(λ)

Rth(λ)＝((Nx+Ny)/2-Nz)×d。

R0(λ) is a numerical value calculated by AxoScan, and refers to Re (λ).

In the present specification, the refractive indices Nx, Ny, Nz are measured using an abbe refractometer (NAR-4T, ATAGO co., ltd.) and a light source using a sodium lamp (λ 589 nm). When the wavelength dependence is measured, the wavelength dependence can be measured by using a combination with an interference filter using a multi-wavelength abbe refractometer DR-M2(ATAGO co., ltd.).

Further, a polymer handbook (JOHN wide & SONS, INC), and the values of catalogs of various optical films can also be used. The values of the average refractive index of the primary optical film are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), polystyrene (1.59).

The method for manufacturing a liquid crystal film of the present invention comprises the following steps in order:

an alignment step of heating the coating film to align the liquid crystal; and

a curing step of curing the oriented coating film,

in the irradiation step, the coating film is irradiated with light through the multi-tone pattern mask, whereby the irradiation amount of light is varied according to the region of the coating film.

The method for producing a functional film of the present invention is a method for producing a functional film having a step of attaching a circularly polarizing plate to the surface of a cured coating film or the back surface of a support after the curing step of the method for producing a liquid crystal film.

< method for producing liquid crystal film >

Hereinafter, an example of a preferred embodiment of the method for producing a liquid crystal film of the present invention will be described with reference to the drawings.

Fig. 1 is a schematic diagram showing an example of a manufacturing apparatus (hereinafter, also referred to as "manufacturing apparatus") for manufacturing a liquid crystal thin film, which executes the method for manufacturing a liquid crystal thin film according to the present invention (hereinafter, also referred to as "the method for manufacturing the present invention"). Fig. 2 is a schematic diagram for explaining an example of the method for manufacturing a liquid crystal thin film by the manufacturing apparatus shown in fig. 1.

The drawings in the present invention are schematic, and the size of each part, the relationship between the thicknesses of the respective layers, the positional relationship, and the like do not necessarily coincide with the actual situation. The same applies to the following figures.

The manufacturing apparatus 100a shown in fig. 1 manufactures a liquid crystal film by roll-to-roll (hereinafter, also referred to as "RtoR") using a long support 12 a. As is well known, RtoR is a manufacturing method in which a long object to be processed is wound into a roll shape, and the object to be processed is fed from the roll, and is conveyed in the longitudinal direction while a process such as film formation is performed, and the processed object to be processed is wound into a roll shape again.

The manufacturing apparatus 100a includes, for example, a conveyance roller 102, a 1 st conveyance unit 120, an application unit 150, a 2 nd conveyance unit 122, an exposure unit 152, a heating unit 154, a curing unit 156, a 3 rd conveyance unit 124, and a take-up roller 116. The 1 st, 2 nd and 3

rd conveying portions

120, 122 and 124 have conveying rollers and the like, and convey long objects to be processed in a predetermined path.

The manufacturing apparatus 100a may include various components, other than those shown in the figure, provided in a known apparatus for forming a film by coating while conveying a long object to be processed, such as a pair of conveying rollers, a guide member for a support, and various sensors.

In the manufacturing apparatus 100a, a roller 130, which is formed by winding the long support 12a, is mounted on the conveying roller 102.

The support body 12a is pulled out from the roller 130 and inserted into a predetermined path that passes through the 1 st transport unit 120, the coating unit 150, the 2 nd transport unit 122, the exposure unit 152, the heating unit 154, the curing unit 156, and the 3 rd transport unit 124 and reaches the take-up roller 116.

Then, the prepared liquid crystal composition to be the cholesteric liquid crystal layer is supplied to the coating nozzle 104 of the coating section 150 and coated.

In the manufacturing apparatus 100a using RtoR, the feeding of the support 12a from the roller 130 and the winding of the support 12a (laminated film 23d) on which the cholesteric liquid crystal layer 18 is formed are performed in synchronization. Thus, while the long support 12a is conveyed along the longitudinal direction on a predetermined conveyance path, the prepared liquid crystal composition is applied to the support 12a in the application section 150, the coating film is exposed to light in the exposure section 152, the coating film is heated in the heating section 154 to align the liquid crystal, and the coating film is cured by ultraviolet irradiation and/or heating in the curing section 156 to form the cholesteric liquid crystal layer 18. The long laminated film 23d having the cholesteric liquid crystal layer 18 formed on the support 12a is wound into a roll shape by the winding roll 116 to form a roll 132.

In the present invention, the liquid crystal film is a film-like material having a cholesteric liquid crystal layer, and in the example shown in fig. 1 and 2, the laminated film 23d in which the cholesteric liquid crystal layer 18 is laminated on the surface of the support 12a is the liquid crystal film of the present invention. The cholesteric liquid crystal layer 18 may be used in a state of being laminated on the support 12a, or may be used after being peeled off from the support 12 a.

In the conveying step shown in S1 in fig. 2, the support 12a fed out from the roller 130 has a pattern mask formed on a resin film such as a PET film.

As the resin film forming the support 12a, various known transparent sheets used as a substrate (support) can be used.

Specifically, a film (resin film) made of various resin materials such as Low Density Polyethylene (LDPE), High Density Polyethylene (HDPE), polyethylene naphthalate (PEN), Polyamide (PA), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyvinyl alcohol (PVA), Polyacrylonitrile (PAN), Polyimide (PI), transparent polyimide, polymethyl methacrylate resin (PMMA), Polycarbonate (PC), polyacrylate, polymethacrylate, polypropylene (PP), Polystyrene (PS), ABS, cycloolefin copolymer (COC), cycloolefin polymer (COP), and cellulose Triacetate (TAC) is preferably exemplified.

In the present invention, a thin film having a surface on which a layer (film) exhibiting a necessary function such as a protective layer, an adhesive layer, a light reflecting layer, an antireflection layer, a light shielding layer, a planarizing layer, a buffer layer, a stress relaxation layer, and a mold releasing layer is formed may be used as the support 12 a.

The pattern mask of the support 12a is a multi-tone pattern mask having 3 or more regions with different transmittances with respect to light (light of a wavelength to which the chiral agent is exposed) irradiated in the exposure portion 152, which will be described later.

Such a pattern mask can be formed by printing, for example, and can be formed as a mask of a desired pattern by printing such that the transmittance of an ink layer formed on the surface of the resin film differs depending on the region. Specifically, it can be formed by gray scale printing (refer to fig. 6) or color printing (refer to fig. 8).

If the thickness of the support body 12a is too thin, the support property is lowered, and bending or the like may occur during transportation. On the other hand, if the thickness is too large, the flexibility is reduced, and the cholesteric liquid crystal layer becomes difficult to be conveyed, becomes large when wound on a roll, and is difficult to be peeled off from the support 12 a.

From the above viewpoint, the thickness of the support 12a is preferably 20 μm to 100 μm, and more preferably 60 μm to 100 μm.

As shown in fig. 1, the support body 12a fed out from the roller 130 passes through the 1 st conveying section 120 to reach the coating section 150. The coating section 150 applies a coating process to the support 12 a. In the example shown in fig. 1, when coating is performed in the coating section 150, the liquid crystal composition is applied to the support 12a by the coating nozzle 104 in a state of being wound around the support roller 106. When the coating is performed by a method such as bar coating in which the coating can be performed without the backup roll 106, the backup roll 106 may be absent.

In the coating step, as shown in S2 in fig. 2, the coating section 104 applies a liquid crystal composition containing a cholesteric liquid crystal compound and a photosensitive chiral reagent to the surface of the support 12a to form a coating film 21 a. The laminate of the support 12a and the coating film 21a is referred to as a laminated thin film 23 a.

The liquid crystal composition will be described in detail later.

As the coating method in the coating step, a known method such as a coating method such as extrusion coating, gravure coating, die coating, bar coating, or applicator coating, or a printing method such as flexographic printing can be applied.

Among them, bar coating is preferable from the viewpoint of suppressing coating unevenness even if unevenness (unevenness due to an ink layer serving as a pattern mask) is present on the surface of the support 12 a.

The coating film 21a may be formed on the pattern mask side of the support 12a, but is preferably formed on the surface opposite to the pattern mask. That is, the pattern mask is preferably formed on the surface (back surface) of the support 12a opposite to the surface on which the coating film 21a is formed.

Next, as shown in fig. 1, the laminated film 23a passes through the 2 nd conveying section 122 to reach the exposure section 152. The exposure section 152 performs an irradiation step on the laminated film 23 a.

In the irradiation step, as shown in S3 in fig. 2, the exposure device 108 irradiates the coating film 21a in an undried state with light from the support 12a side, that is, through the pattern mask. The light irradiated by the exposure device 108 is light of a wavelength to which the chiral agent in the coating film 21a (liquid crystal composition) is sensitive. Thus, the coating film 21b exposed by the exposure process is formed. The photosensitive chiral agent is exposed to light in the exposed coating film 21b, and the structure thereof changes.

The laminate of the support 12a and the exposed coating film 21b is referred to as a laminated thin film 23 b.

Here, the pattern mask is a multi-tone pattern mask having 3 or more regions having different transmittances of light of wavelengths to which the chiral agent is exposed. Therefore, the exposed coating film 21b is irradiated with light of different irradiation amounts for each region in accordance with the pattern of the pattern mask.

Here, the amount of change in the structural change due to the exposure of the photosensitive chiral agent differs depending on the exposure dose. Therefore, the amount of change in the structure of the exposed coating film 21b, which becomes a chiral agent, varies from region to region depending on the pattern of the pattern mask.

The wavelength of light used for exposure may be set according to the type of the photosensitive chiral agent or the like.

The amount of light irradiation may be set according to the type of the photosensitive chiral agent, the light transmittance of the pattern mask, and the like.

Next, as shown in fig. 1, the laminated film 23b is conveyed to the heating section 154. In the heating device 110, the coating film of the laminated thin film 23b is dried and subjected to an alignment treatment.

In the alignment step, as shown in S4 in fig. 2, the exposed coating film 21b is heated by the heating device 110, whereby the liquid crystal compound in the coating film 21b is aligned. By the heat treatment, a coating film 21c is formed in which the liquid crystal compound is aligned according to the structure of the chiral agent.

Here, as described above, in the coating film 21c, there are 3 or more regions different in the exposure amount. Therefore, the length of the helical pitch which becomes the cholesteric liquid crystal phase in each region differs depending on the exposure amount. Although described in detail later, the selective reflection wavelength in the cholesteric liquid crystal phase depends on the pitch of the helical structure in the cholesteric liquid crystal phase. Therefore, by forming 3 or more regions having different lengths of the helical pitch of the cholesteric liquid crystal phase, 3 or more regions having different selective reflection wavelengths are formed.

The laminate of the support 12a and the oriented coating film 21c is referred to as a laminated thin film 23 c.

Next, as shown in fig. 1, the laminated film 23c is conveyed to the curing section 156. In the curing section 156, the laminated film 23c is subjected to a curing process.

In the curing step, the aligned coating film 21c is cured by the curing section 112 to form the cholesteric liquid crystal layer 18, as shown by S5 in fig. 2. Thus, a liquid crystal film having the cholesteric liquid crystal layer 18 was produced. The laminate of the support 12a and the cholesteric liquid crystal layer 18 is a laminate film 23 d.

As a method for curing the coating film 21c, a known curing method such as photocuring by irradiation with light such as ultraviolet light or thermal curing by heating can be used.

When curing is performed by light irradiation, it is preferable to irradiate the coating film 21c with light from the side opposite to the pattern mask.

Next, the produced liquid crystal film (laminated film 23d) is wound into a roll shape by the winding roll 116 by the 3 rd conveying unit 124 to be a roll 132.

The cholesteric liquid crystal layer of the liquid crystal film thus produced has a structure in which 3 or more regions having different selective reflection wavelengths are formed in a pattern corresponding to the mask pattern, and therefore each region reflects light having a selective reflection wavelength, and an image having a color and a pattern corresponding thereto can be displayed.

As in the conventional art, when a coating liquid of cholesteric liquid crystal is applied onto a substrate and dried, and then ultraviolet rays are irradiated onto the coating film and cured, in a structure in which exposure is performed using a pattern mask, the liquid crystal compound in the coating film is hard to move due to drying, and therefore, even if exposure is performed, the amount of change in pitch of the helical structure of the liquid crystal compound becomes smaller than a desired amount of change. Therefore, there is a problem that a desired selective reflection wavelength, that is, a desired color tone cannot be reproduced.

Even in this case, the following problems are known: if the exposure amount is increased, a desired selective reflection wavelength can be set, but if the exposure amount is increased, light leaks to the unexposed portion, the unexposed portion is also exposed, and the boundary (between regions of different selective reflection wavelengths) between the exposed portion and the unexposed portion becomes blurred, and fineness cannot be sufficiently obtained.

In addition, in a configuration using a binary pattern mask having a light shielding portion and a light transmitting portion as a pattern mask, when the binary pattern mask is used, the pattern mask needs to be changed to perform multiple exposures when a cholesteric liquid crystal layer forms a region in which 3 or more types of reflection wavelengths are selected. Therefore, the following problems are known: to form a more multicolored cholesteric liquid crystal layer requires many processing steps and is inefficient to manufacture.

In contrast, in the production method of the present invention, since the coating film of the liquid crystal composition is exposed to light in an undried state before being heated and dried, the liquid crystal compound in the coating film is easily moved, and the amount of change in the pitch of the helical structure of the liquid crystal compound can be set to a desired amount of change even with a small amount of exposure. Therefore, a problem that a desired selective reflection wavelength, that is, a desired color tone can be easily reproduced. Further, since the exposure amount is small, light leakage to adjacent regions (regions with different exposure amounts) can be suppressed, and a fine image can be obtained without blurring the boundary between regions with different selective reflection wavelengths.

Further, since a multi-tone pattern mask having 3 or more regions with different transmittance of light of a wavelength which is sensitive to the chiral agent is used as the pattern mask, 3 or more regions with different selective reflection wavelengths can be formed in the cholesteric liquid crystal layer by one exposure. Therefore, a multicolor cholesteric liquid crystal layer can be efficiently produced with a small number of steps.

As described above, the manufacturing method of the present invention can obtain a cholesteric liquid crystal layer capable of displaying an image of a fine and desired color gradation, and has high productivity.

Here, as long as the pattern mask is a mask having 3 or more regions having different transmittances of light of wavelengths that are sensitive to the chiral agent, the pattern mask preferably has 8 or more regions having different transmittances, more preferably 256 or more, from the viewpoint of enabling reproduction of more colors and improvement of gradation.

In the example shown in fig. 1, the manufactured liquid crystal film is wound in a roll shape, but the invention is not limited to this, and the manufactured liquid crystal film may be cut into a predetermined size.

When the method of curing the coating film in the curing step is photocuring, the wavelength of the light irradiated in the curing step is preferably a wavelength different from the wavelength of the light irradiated in the irradiation step, and the wavelength of the light irradiated in the irradiation step is preferably a wavelength longer than the wavelength of the light irradiated in the curing step. Specifically, the wavelength of light irradiated in the irradiation step is a wavelength at which the chiral agent is sensitive to light, and is preferably a wavelength at which the polymerization initiator is not cleaved.

By making the wavelengths of the light irradiated in the curing step and the irradiation step different from each other, the curing of the coating film by the light irradiation in the irradiation step can be suppressed, and the amount of change in the pitch of the helical structure of the liquid crystal compound can be made a desired amount of change.

The wavelength of the light irradiated in the irradiation step may be selected from wavelengths at which the chiral agent is sensitive to light, depending on the type of the chiral agent. Specifically, the wavelength of the light irradiated in the irradiation step is preferably 350nm to 400 nm. That is, a chiral agent sensitive to light in this wavelength range is preferably used.

The irradiation amount of the light irradiated in the irradiation step may be set to a desired selective reflection wavelength depending on the type of the chiral agent.

The wavelength of light irradiated in the curing step may be selected according to the kind of a polymerization initiator or the like. Specifically, the wavelength of the light irradiated in the curing step is preferably 300nm to 350 nm. That is, it is preferable to use a polymerization initiator capable of initiating a polymerization reaction in this wavelength range.

The irradiation amount of light to be irradiated in the curing step may be set according to the kind of the polymerization initiator and the like.

In the example shown in fig. 1, the light irradiation is performed once in the irradiation step, but the light irradiation may be performed in a manner divided into two or more times. For example, the irradiation step may have a first irradiation step and a second irradiation step.

By configuring the irradiation step such that the light irradiation is divided into two or more times, the structural change of the chiral agent due to the exposure can be more appropriately adjusted, and the desired selective reflection wavelength can be set.

In this case, the irradiation amount of light in the first irradiation step is preferably smaller than the irradiation amount of light in the second irradiation step.

Regarding the structural change of the chiral agent, when the total amount of irradiation with light is small, the amount of change with respect to the amount of irradiation with light is large, and when the total amount of irradiation with light is increased, the amount of change with respect to the amount of irradiation with light is decreased. Therefore, by making the irradiation amount of light in the first irradiation step smaller than that in the second irradiation step, the structural change of the chiral agent caused by exposure can be more appropriately adjusted.

In the irradiation step, the total of the irradiation amounts in the first irradiation step and the second irradiation step is preferably 200mJ/cm²The following.

By setting the total irradiation dose to 200mJ/cm²It is preferable to prevent the unexposed portion from being exposed in the following manner.

In addition, the peak wavelengths of the light to be irradiated in the first irradiation step and the second irradiation step may be different from each other.

The peak wavelength of the light in the first irradiation step is set to a wavelength that is shifted from the peak wavelength of the light to which the chiral reagent is exposed, and the peak wavelength of the light in the second irradiation step is made to coincide with the peak wavelength of the light to which the chiral reagent is exposed, whereby the amount of light irradiation can be substantially adjusted.

Specifically, for example, if the light absorption peak of the chiral agent is 365nm and has a spectrum inclined in the range of 250nm to 450nm, the irradiation amount of light can be substantially adjusted by irradiating light of 265nm with an inclination in the first irradiation step and light of 365nm with a peak in the second irradiation step.

In the example shown in fig. 1, the cholesteric liquid crystal layer 18 is wound around the roller 132 immediately after being formed, but a protective film or the like may be attached to the surface of the cholesteric liquid crystal layer 18 before being wound around the roller 132.

As shown in S6 in fig. 2, the following configuration may be adopted: after the liquid crystal film is produced, a step of transferring the cholesteric liquid crystal layer 18 to the circularly polarizing plate 16 is provided, and a functional film having the cholesteric liquid crystal layer 18 and the circularly polarizing plate 16 is produced.

Specifically, the circularly polarizing plate 16 may be attached to the surface of the cholesteric liquid crystal layer 18 after the cholesteric liquid crystal layer 18 is formed and before the cholesteric liquid crystal layer is wound around the roller 132, or the circularly polarizing plate 16 may be attached to the surface of the cholesteric liquid crystal layer 18 by mounting the roller 132 in a normal bonding apparatus after the cholesteric liquid crystal layer 18 is formed and after the cholesteric liquid crystal layer is wound around the roller 132.

Further, the method may further include a step of peeling off the support 12a after the circularly polarizing plate 16 is attached.

The circularly polarizing plate 16 is not limited, and a circularly polarizing plate having a structure in which a linearly polarizing plate and a λ/4 plate are stacked may be used. The circularly polarizing plate 16 transmits circularly polarized light in the direction opposite to the rotational direction of the circularly polarized light reflected by the cholesteric liquid crystal layer 18.

By forming the cholesteric liquid crystal layer 18 and the circularly polarizing plate 16 in a stacked manner, one of circularly polarized light beams having a selective reflection wavelength is reflected by the cholesteric liquid crystal layer 18 out of light beams entering from the cholesteric liquid crystal layer 18 side (hereinafter, also referred to as the front side), and the other light beams pass through the cholesteric liquid crystal layer 18 and enter the circularly polarizing plate 16. Of the light incident on the circularly polarizing plate 16, the other circularly polarized light transmits the circularly polarizing plate 16.

On the other hand, light incident from the circularly polarizing plate 16 side (hereinafter, also referred to as the back side) is converted into another circular polarization by the circularly polarizing plate 16, transmits the circularly polarizing plate 16, and is incident on the cholesteric liquid crystal layer 18.

The other circularly polarized light of the transmissive circularly polarizing plate 16 is in a rotational direction opposite to the rotational direction of the helix of the cholesteric liquid crystal phase of the cholesteric liquid crystal layer 18, and therefore is not reflected by the cholesteric liquid crystal layer 18 and is transmitted through the cholesteric liquid crystal layer 18.

Therefore, when the functional film in which the cholesteric liquid crystal layer 18 and the circularly polarizing plate 16 are laminated is viewed from the front side, the other side of the functional film is viewed by the other circularly polarized light which is incident and transmitted from the back side, and light of the selected reflection wavelength in the reflection region of the cholesteric liquid crystal layer 18 is viewed. That is, when viewed from the front side, the other side of the functional film and the pattern image corresponding to the pattern shape of the cholesteric liquid crystal layer 18 are visually recognized.

On the other hand, when the functional film is viewed from the back side, the other side of the functional film is viewed by the left-handed circularly polarized light incident and transmitted from the front side, but an image displayed by the cholesteric liquid crystal layer 18 which can be viewed from the front side cannot be viewed.

In this way, the functional film in which the cholesteric liquid crystal layer 18 and the circularly polarizing plate 16 are laminated can be a film having transparency and having an image viewed from one surface side (cholesteric liquid crystal layer side) different from an image viewed from the other surface side (circularly polarizing plate side).

In addition, an adhesive layer may be provided between the cholesteric liquid crystal layer 18 and the circularly polarizing plate 16.

The structure of attaching the circularly polarizing plate to the surface of the cholesteric liquid crystal layer is not particularly limited, and the circularly polarizing plate may be attached to the back surface of the support. That is, a functional film including a cholesteric liquid crystal layer, a support, and a circularly polarizing plate may be used.

In the example shown in fig. 1 and 2, the support 12a has a pattern mask, but the present invention is not limited to this, and a thin film having a pattern mask may be attached to the support.

FIG. 3 schematically shows a manufacturing apparatus for carrying out another example of the method for manufacturing a liquid crystal film according to the present invention.

The manufacturing apparatus 100b shown in fig. 3 manufactures a liquid crystal film by RtoR. The manufacturing apparatus 100b includes a conveyance roller 102, a supply roller 140, a 1 st conveyance unit 120, a coating unit 150, a 2 nd conveyance unit 122, an exposure unit 152, a heating unit 154, a curing unit 156, a 3 rd conveyance unit 124, a recovery roller 144, and a take-up roller 116.

The manufacturing apparatus 100b shown in fig. 3 is the same as the manufacturing method based on the manufacturing apparatus 100a shown in fig. 1 except that it includes the supply roller 140 and the recovery roller 144, and therefore the same portions are denoted by the same reference numerals, and the following description will be given mainly of different portions. The manufacturing method by the manufacturing apparatus 100b shown in fig. 3 is the same as the manufacturing method by the manufacturing apparatus 100a shown in fig. 1 except that the manufacturing method includes a step of attaching the mask film 14 to the support 12b and a step of peeling, and therefore, the following description will be given mainly of different steps.

In the manufacturing apparatus 100b, a roller 130, which is formed by winding the long support body 12b, is mounted on the conveying roller 102. In addition, no pattern mask is formed on the support 12 b.

The support body 12b is pulled out from the roller 130 and inserted into a predetermined path that passes through the 1 st transport unit 120, the coating unit 150, the 2 nd transport unit 122, the exposure unit 152, the heating unit 110, the curing unit 154, and the 3 rd transport unit 124 and reaches the take-up roller 116.

The prepared liquid crystal composition to be the cholesteric liquid crystal layer is filled in a predetermined position of the coating portion 104.

The supply roller 140 is provided with a roller 142 that is wound around the mask film 14 (see fig. 4) having the base film 20 and the ink layer 22 formed as a pattern mask on the surface of the base film 20, and the mask film 14 is pulled out from the roller 142 and inserted into a predetermined transport path from the 1 st transport unit 120 to the 3 rd transport unit 124. The supply roller 140 is disposed between the conveying roller and the 1 st conveying portion 120 in the conveying direction of the support body 12 b.

At the position of the transport roller of the 3 rd transport unit 124, the mask film 14 is peeled off from the support 12b, and the mask film 14 peeled off from the support 12b is inserted into the recovery roller 144. The recovery roller 144 is disposed between the 3 rd conveying unit 124 and the take-up roller 116 in the conveying direction of the support 12b, and recovers the mask film 14 to the roller 146.

In the manufacturing apparatus 100b, the support 12b and the support 12b (laminated film 23d) on which the cholesteric liquid crystal layer 18 is formed are fed from the roller 130 and wound up in synchronization with each other.

First, while a long support 12b is conveyed in the longitudinal direction along a predetermined conveyance path, a mask film 14 is attached to the back surface of the support 12b to form a laminated film 25a (see fig. 4).

Next, the liquid crystal composition prepared in the coating section 104 is coated on the surface of the support 12b to form a laminated film 25b (see fig. 5).

Next, the coating film is exposed to light in an exposure section 152. At this time, the coating film 21a is irradiated with light from the side of the mask film 14 attached to the support 12 b.

Here, the pattern mask included in the mask film 14 is a multi-tone pattern mask in which 3 or more regions having different transmittances with respect to light of a wavelength to which the chiral agent is exposed are formed by the ink layer 22. Therefore, by irradiating the coating film 21a with light through the pattern mask, it is possible to irradiate different amounts of light for each region in accordance with the pattern of the pattern mask, and to form 3 or more regions different in selective reflection wavelength.

In this case, the pattern mask (ink layer 22) side is preferably attached to the support 12 b.

In the manufacturing method of the present invention, since the support 12b is conveyed by RtoR and light is irradiated, light enters the coating film from various directions, and thus light may leak and the boundary of the region may be blurred. Therefore, by attaching the pattern mask to the support 12b and shortening the distance between the pattern mask and the coating film, light leakage can be suppressed and a finer image can be formed.

Next, the coating film is heated in the heating unit 110 to align the liquid crystal, and further, the coating film is cured by ultraviolet irradiation and/or heating in the curing unit 112 to form the cholesteric liquid crystal layer 18, thereby forming a laminated film 25e including the mask film 14, the support 12b, and the cholesteric liquid crystal layer 18.

Then, the mask film 14 is peeled off from the support 12 b. The peeled mask film 14 is wound in a roll shape on a recovery roll 144 to form a roll 146.

In the winding roller 116, the long laminated film 23d having the cholesteric liquid crystal layer 18 formed on the support 12b is wound in a roll shape to form a roller 132.

In this manner, the base film (mask film 14) on which the pattern mask is formed may be bonded to the back surface of the support and subjected to the irradiation step (exposure).

In the example shown in fig. 3, the coating step, the irradiation step, the alignment step, and the curing step are performed in a state where the mask film 14 is attached to the support 12b, but the irradiation step may be performed at least in a state where the mask film 14 is attached to the support 12b, and the other steps may be performed in a state where the mask film 14 is not attached.

For example, the mask film 14 may be attached to the support 12b after the coating step. Alternatively, the roller 130 in which the laminate having the mask film 14 attached to the support 12b is wound into a roll shape may be mounted on the transport roller 102, and the laminate having the mask film 14 attached to the support 12b may be sent out as the object to be processed.

For example, the mask film 14 may be peeled between the irradiation step and the alignment step, or the mask film 14 may be peeled between the alignment step and the curing step. Alternatively, the mask film 14 may be not peeled off, and the mask film 14 may be stacked on the winding roller 116 and wound in a roll shape to form the roller 132.

In the curing step, when the mask film 14 is attached to the support 12b, it is preferable to irradiate light to the surface opposite to the mask film 14.

In the example shown in fig. 1 and 2, the cholesteric liquid crystal layer 18 is formed in 1 layer on the support 12a, but the present invention is not limited to this, and a cholesteric liquid crystal layer in 2 layers or more may be formed by performing a combination of 2 or more coating steps, irradiation steps, alignment steps, and curing steps.

For example, a support on which the cholesteric liquid crystal layer is formed may be supplied to the manufacturing apparatus again as a treatment object, and the cholesteric liquid crystal layer may be formed on the cholesteric liquid crystal layer. Alternatively, the manufacturing apparatus may be configured to have a combination of 2 or more coating units, exposure units, heating units, and curing units between the transport roller and the take-up roller in the transport direction of the support.

When the irradiation step is performed 2 or more times, it is preferable that the light is irradiated through a pattern mask having the same pattern, and the irradiation amounts of the light in the respective irradiation steps are different from each other.

Thus, when viewed from a direction perpendicular to the surface of the cholesteric liquid crystal layer, the selective reflection wavelength in the same position differs among the cholesteric liquid crystal layers. With this configuration, the color of light having a selective reflection wavelength and mixed with a plurality of cholesteric liquid crystal layers can be visually recognized. That is, various colors can be reproduced. For example, when the cholesteric liquid crystal layer has a 3-layer structure, each cholesteric liquid crystal layer reflects red, green, and blue, and can reproduce white.

(cholesteric liquid Crystal layer)

Next, the cholesteric liquid crystal layer will be described.

A cholesteric liquid crystal layer refers to a layer that includes a cholesteric liquid crystal phase. The cholesteric liquid crystal layer is a layer in which a cholesteric liquid crystal phase is fixed.

The cholesteric liquid crystal layer reflects right-handed circularly polarized light or left-handed circularly polarized light of a selected reflection wavelength and transmits the other circularly polarized light of the selected reflection wavelength and light of other wavelength regions.

The structure for fixing the cholesteric liquid crystal phase may be any structure as long as it retains the alignment of the liquid crystal compound that becomes the cholesteric liquid crystal phase, and typically, the polymerizable liquid crystal compound is brought into an aligned state of the cholesteric liquid crystal phase, and then polymerized and cured by ultraviolet irradiation, heating, or the like to form a layer having no fluidity and to change the alignment system by an external magnetic field or an external force. In the structure in which the cholesteric liquid crystal phase is fixed, the liquid crystal compound may not exhibit liquid crystallinity as long as the optical properties of the cholesteric liquid crystal phase are maintained. For example, the polymerizable liquid crystal compound may be polymerized to have a high molecular weight by a curing reaction, and may lose its liquid crystal property.

The selective reflection wavelength λ of the cholesteric liquid crystal phase depends on the pitch P of the helical structure in the cholesteric liquid crystal phase (i.e., the period of the helix), and follows the relationship between the average refractive index n of the cholesteric liquid crystal phase and λ n × P. Therefore, the selective reflection wavelength can be adjusted by adjusting the pitch of the helical structure. The pitch of the cholesteric liquid crystal phase depends on the kind of chiral agent used together with the polymerizable liquid crystal compound or the concentration of the chiral agent added, and thus a desired pitch can be obtained by adjusting the above.

Further, it was revealed that the half-value width Δ λ (nm) of the selective reflection band (circularly polarized light reflection band) of selective reflection is in a relationship of Δ λ ═ Δ n × P depending on the refractive index anisotropy Δ n of the cholesteric liquid crystal phase and the pitch P of helices. Therefore, the control of selecting the width of the reflection band can be performed by adjusting Δ n. Δ n can be adjusted by the type and the mixing ratio of the liquid crystal compounds forming the cholesteric liquid crystal layer, and the temperature at the time of alignment. It is also known that the reflectance in the cholesteric liquid crystal phase depends on Δ n, and when the same degree of reflectance is obtained, the larger Δ n is, the smaller the number of helical pitches is, that is, the smaller the film thickness is.

As the method for measuring the spin direction and pitch of the helix, the method described in "liquid crystal chemistry experiments entry" published by Sigma in 2007, page 46 and "liquid crystal handbook" edited committee of liquid crystal handbook, Wan 196 can be used.

The reflected light of the cholesteric liquid crystal phase is circularly polarized light. The reflected light is either right-handed circularly polarized light or left-handed circularly polarized light, and the cholesteric liquid crystal phase depends on the twist direction of the helix. In selective reflection of circularly polarized light based on a cholesteric liquid crystal phase, when the twist direction of the helix of the cholesteric liquid crystal phase is right, right-handed circularly polarized light is reflected, and when the twist direction of the helix is left, left-handed circularly polarized light is reflected.

The rotational direction of the cholesteric liquid crystal phase can be adjusted by the type of the liquid crystal compound forming the cholesteric liquid crystal layer or the type of the chiral agent added.

In order to widen the wavelength range of the reflected light, it can be realized by sequentially stacking layers in which the selective reflection wavelength λ is shifted. Further, a technique for expanding the wavelength range by a method of changing the pitch of helices in a layer called a pitch gradient method in stages is also known, and specifically, the methods described in Nature 378, 467-469(1995), Japanese patent laid-open No. 6-281814, and Japanese patent laid-open No. 4990426 are mentioned.

In the present invention, the selective reflection wavelength in the region of the cholesteric liquid crystal layer can be set to any one of the visible light (about 380 to 780 nm) and the near infrared light (about 780 to 2000 nm), and the setting method is as described above.

As described above, in the liquid crystal film produced by the production method of the present invention, the cholesteric liquid crystal layer has 3 or more regions having different selective reflection wavelengths.

For example, the cholesteric liquid crystal layer may have a structure having a region having a selective reflection wavelength of red light (light in a wavelength region of 620nm to 750 nm), a region having a selective reflection wavelength of green light (light in a wavelength region of 495nm to 570 nm), and a region having a selective reflection wavelength of blue light (light in a wavelength region of 420nm to 490 nm).

Further, the reflective film may have a reflective region that selectively reflects infrared rays. The infrared ray is light in a wavelength range of more than 780nm and 1mm or less, and the near-infrared region is light in a wavelength range of more than 780nm and 2000nm or less.

(liquid Crystal composition)

As a material for the cholesteric liquid crystal layer, a liquid crystal composition containing a liquid crystal compound and a photosensitive chiral agent is exemplified. The liquid crystal compound is preferably a polymerizable liquid crystal compound.

The liquid crystal composition containing the polymerizable liquid crystal compound further contains a surfactant, a polymerization initiator, and the like.

A polymerizable liquid crystal compound- -

The polymerizable liquid crystal compound may be a rod-like liquid crystal compound or a discotic liquid crystal compound, and is preferably a rod-like liquid crystal compound.

Examples of the rod-shaped polymerizable liquid crystal compound forming the cholesteric liquid crystal layer include a rod-shaped nematic liquid crystal compound. As the nematic liquid crystal compound in rod form, it is preferable to use methyleneamines, azoxides, cyanobiphenyls, cyanobenzenes, benzoates, cyclohexanecarboxylates, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes, and vinylcyclohexylbenzonitriles. Not only a low molecular liquid crystal compound but also a high molecular liquid crystal compound can be used.

The polymerizable liquid crystal compound is obtained by introducing a polymerizable group into a liquid crystal compound. Examples of the polymerizable group include an unsaturated polymerizable group, an epoxy group, and an aziridine group, an unsaturated polymerizable group is preferable, and an ethylenically unsaturated polymerizable group is particularly preferable. The polymerizable group can be introduced into the molecule of the liquid crystal compound by various methods. The number of the polymerizable groups of the polymerizable liquid crystal compound is preferably 1 to 6, more preferably 1 to 3. Examples of the polymerizable liquid crystal compound include compounds described in Makromol. chem., 190, 2255 (1989), Advanced Materials 5, 107 (1993), U.S. Pat. No. 4683327, U.S. Pat. No. 5622648, U.S. Pat. No. 5770107, International publication WO95/022586, International publication WO95/024455, International publication WO97/000600, International publication WO98/023580, International publication WO98/052905, Japanese patent laid-open No. 1-272551, Japanese patent laid-open No. 6-016616, Japanese patent laid-open No. 7-110469, Japanese patent laid-open No. 11-080081, Japanese patent laid-open No. 2001 and 328973. 2 or more polymerizable liquid crystal compounds may be used simultaneously. When 2 or more polymerizable liquid crystal compounds are used together, the alignment temperature can be lowered.

Specific examples of the polymerizable liquid crystal compound include compounds represented by the following formulas (1) to (11).

[ chemical formula 1]

[ chemical formula 2]

[ Compound (11) wherein X is¹Is an integer of 2 to 5.]

In addition, as polymerizable liquid crystal compounds other than the above, cyclic organopolysiloxane compounds having a cholesteric phase, as disclosed in Japanese patent application laid-open No. 57-165480, and the like, can be used. Further, as the polymer liquid crystal compound, a polymer in which a mesogenic group which exhibits liquid crystal is introduced into a main chain, a side chain, or both of the main chain and the side chain, a polymer cholesteric liquid crystal in which a cholesteric group is introduced into a side chain, a liquid crystal polymer as disclosed in Japanese patent laid-open No. 9-133810, a liquid crystal polymer as disclosed in Japanese patent laid-open No. 11-293252, or the like can be used.

The amount of the polymerizable liquid crystal compound added to the liquid crystal composition is preferably 75 to 99.9% by mass, more preferably 80 to 99% by mass, and particularly preferably 85 to 90% by mass, based on the mass of the solid content (the mass of the solvent removed) of the liquid crystal composition.

- -chiral reagent (optically active compound) - -

The chiral agent has the function of derivatizing the helical structure of the cholesteric liquid crystal phase. Since the twist direction or the pitch of the helix derived from the compound is different, the chiral compound may be selected depending on the purpose.

The chiral reagent is not particularly limited, and known compounds (for example, those described in the handbook of liquid crystal devices, chapter 3, items 4 to 3, TN (twisted nematic), STN (Super-twisted nematic) and chiral reagents for Japanese society of academic Press 142, pp 199, 1989), isosorbide and isomannide derivatives can be used.

The chiral agent usually contains an asymmetric carbon atom, but an axially asymmetric compound or a surface asymmetric compound containing no asymmetric carbon atom can also be used as the chiral agent. Examples of the axially asymmetric compound or the surface asymmetric compound include binaphthyl, spiroalkene, p-cycloaralkyl, and derivatives thereof. The chiral agent may have a polymerizable group. When both the chiral agent and the liquid crystal compound have a polymerizable group, a polymer having a repeating unit derived from the polymerizable liquid crystal compound and a repeating unit derived from the chiral agent can be formed by a polymerization reaction of the polymerizable chiral agent and the polymerizable liquid crystal compound. In this embodiment, the polymerizable group of the polymerizable chiral agent is preferably the same type of group as the polymerizable group of the polymerizable liquid crystal compound. Therefore, the polymerizable group of the chiral agent is also preferably an unsaturated polymerizable group, an epoxy group or an aziridine group, more preferably an unsaturated polymerizable group, and particularly preferably an ethylenically unsaturated polymerizable group.

Further, the chiral agent may be a liquid crystal compound.

In addition, as described above, when a cholesteric liquid crystal layer is produced, the size of the helical pitch of the cholesteric liquid crystal phase is controlled by light irradiation. Therefore, a chiral agent (also referred to as a photosensitive chiral agent) that can sense light and change the helical pitch of a cholesteric liquid crystal phase is used.

The photosensitive chiral agent is a compound that absorbs light to change the structure thereof, thereby changing the helical pitch of the cholesteric liquid crystal phase. Such a compound is preferably a compound that causes at least one of a photoisomerization reaction, a photodimerization reaction, and a photodecomposition reaction.

The compound causing photoisomerization reaction means a compound causing stereoisomerisation or structural isomerisation by the action of light. Examples of the photoisomerization compound include azobenzene compounds and spiropyran compounds.

The compound which causes the photo-dimerization reaction is a compound which causes addition reaction between 2 groups by irradiation with light and is cyclized. Examples of the photo-dimerization compound include cinnamic acid derivatives, coumarin derivatives, chalcone derivatives, and benzophenone derivatives.

As the photosensitive chiral agent, a chiral agent represented by the following general formula (I) can be preferably mentioned. The chiral agent can change the alignment structure such as the helical pitch (twist force, helical twist angle) of the cholesteric liquid crystal phase according to the amount of light upon irradiation with light.

[ chemical formula 3]

General formula (I)

In the general formula (I), Ar¹And Ar²Represents an aryl or heteroaromatic ring group.

From Ar¹And Ar²The aryl group represented may have a substituent ofAnd a substituent, and the total number of carbon atoms is preferably 6 to 40, more preferably 6 to 30. As the substituent, for example, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, a hydroxyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, a carboxyl group, a cyano group or a heterocyclic group is preferable, and a halogen atom, an alkyl group, an alkenyl group, an alkoxy group, a hydroxyl group, an acyloxy group, an alkoxycarbonyl group or an aryloxycarbonyl group is more preferable.

Among such aryl groups, preferred is an aryl group represented by the following general formula (III) or (IV).

[ chemical formula 4]

R in the general formula (III)¹And R in the general formula (IV)²Each independently represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, an alkoxy group, a hydroxyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, a carboxyl group or a cyano group. Among them, a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an aryl group, an alkoxy group, a hydroxyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, or an acyloxy group is preferable, and an alkoxy group, a hydroxyl group, or an acyloxy group is more preferable.

L in the general formula (III)¹And L in the general formula (IV)²Each independently represents a halogen atom, an alkyl group, an alkoxy group or a hydroxyl group, preferably an alkoxy group or a hydroxyl group having 1 to 10 carbon atoms.

l represents an integer of 0 or 1 to 4, preferably 0 or 1. m represents an integer of 0 or 1 to 6, preferably 0 or 1. When L and m are 2 or more, L¹And L²May represent mutually different groups.

From Ar¹And Ar²The heteroaromatic ring group represented by (a) may have a substituent, and preferably has 4 to 40 total carbon atoms, and more preferably has 4 to 30 total carbon atoms. As the substituent, for example, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, a hydroxyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, or a cyano group is preferable, and a halogen atom, an alkyl group, an alkenyl group, an aryl group, an alkoxy group, or an acyloxy group is more preferable.

Examples of the heteroaromatic ring group include a pyridyl group, a pyrimidyl group, a furyl group, and a benzofuryl group, and among them, a pyridyl group or a pyrimidyl group is preferable.

The content of the chiral agent in the liquid crystal composition is preferably 0.01 to 200 mol%, more preferably 1 to 30 mol% based on the amount of the polymerizable liquid crystalline compound.

Polymerization initiator- -

When the liquid crystal composition contains a polymerizable compound, it preferably contains a polymerization initiator. In the embodiment of carrying out the polymerization reaction by ultraviolet irradiation, the polymerization initiator to be used is preferably a photopolymerization initiator which can initiate the polymerization reaction by ultraviolet irradiation. Examples of the photopolymerization initiator include an α -carbonyl compound (described in U.S. Pat. Nos. 2367661 and 2367670), a ketol ether (described in U.S. Pat. No. 2448828), an α -hydrocarbon-substituted aromatic acyloin compound (described in U.S. Pat. No. 2722512), a polynuclear quinone compound (described in U.S. Pat. Nos. 3046127 and 2951758), a combination of a triarylimidazole dimer and p-aminophenyl ketone (described in U.S. Pat. No. 3549367), an acridine and phenazine compound (described in Japanese patent application laid-open No. Sho 60-105667 and U.S. Pat. No. 4239850), and an oxadiazole compound (described in U.S. Pat. No. 4212970).

The content of the photopolymerization initiator in the liquid crystal composition is preferably 0.1 to 20% by mass, and more preferably 0.5 to 12% by mass, based on the content of the polymerizable liquid crystal compound.

-a cross-linking agent- -

The liquid crystal composition may optionally contain a crosslinking agent in order to improve the film strength after curing and to improve the durability. As the crosslinking agent, a crosslinking agent that cures by ultraviolet rays, heat, moisture, or the like can be preferably used.

The crosslinking agent is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include polyfunctional acrylate compounds such as trimethylolpropane tri (meth) acrylate and pentaerythritol tri (meth) acrylate; epoxy compounds such as glycidyl (meth) acrylate and ethylene glycol diglycidyl ether; aziridine compounds such as 2, 2-dihydroxymethylbutanol-tris [3- (1-aziridinyl) propionate ], 4-bis (ethyleneiminocarbonylamino) diphenylmethane and the like; isocyanate compounds such as hexamethylene diisocyanate and biuret type isocyanate; a polyoxazoline compound having an oxazoline group in a side chain; and alkoxysilane compounds such as vinyltrimethoxysilane and N- (2-aminoethyl) 3-aminopropyltrimethoxysilane. In addition, a known catalyst can be used depending on the reactivity of the crosslinking agent, and productivity can be improved in addition to the improvement of the strength and durability of the membrane. These may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The content of the crosslinking agent is preferably 3 to 20% by mass, more preferably 5 to 15% by mass. If the content of the crosslinking agent is less than 3% by mass, the effect of increasing the crosslinking density is obtained, and if it exceeds 20% by mass, the stability of the cholesteric liquid crystal layer is lowered.

Other additives- -

If necessary, a surfactant, a polymerization inhibitor, an antioxidant, a horizontal alignment agent, an ultraviolet absorber, a light stabilizer, a coloring material, metal oxide fine particles, and the like may be further added to the liquid crystal composition within a range not to deteriorate optical properties and the like.

The liquid crystal composition may contain a solvent. The solvent is not particularly limited and can be appropriately selected according to the purpose, and an organic solvent is preferably used.

The organic solvent is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include ketones such as methyl ethyl ketone and methyl isobutyl ketone, alkyl halides, amides, sulfoxides, heterocyclic compounds, hydrocarbons, esters, and ethers. These can be used alone in 1 kind, also can be used simultaneously in more than 2 kinds. Of these, ketones are particularly preferable in view of environmental load. The above-mentioned components such as the above-mentioned monofunctional polymerizable monomer can function as a solvent.

(lambda/4 plate)

The λ/4 plate constituting the circularly polarizing plate is a conventionally known λ/4 plate, and when the light incident on the λ/4 plate is linearly polarized, it is emitted as circularly polarized light, and when the light incident on the λ/4 plate is circularly polarized, it is emitted as linearly polarized light.

The λ/4 plate is a plate having a function of converting linearly polarized light of a certain specific wavelength into circularly polarized light or converting circularly polarized light into linearly polarized light. More specifically, the plate has an in-plane retardation value Re (λ) ═ λ/4 (or an odd multiple thereof) at a predetermined wavelength λ nm. This formula may be implemented at any wavelength in the visible light region (for example, 550 nm).

The λ/4 plate may have a structure including only the optically anisotropic layer, or may have a structure in which the optically anisotropic layer is formed on a support, and when the λ/4 plate has a support, the combination of the support and the optically anisotropic layer is referred to as a λ/4 plate.

The λ/4 plate can be a known λ/4 plate.

In the liquid crystal film of the present invention, the λ/4 plate preferably has a small Rth (550) as retardation in the thickness direction.

Specifically, Rth (550) is preferably from-50 nm to 50nm, more preferably from-30 nm to 30nm, and further preferably Rth (. lamda.) is 0. This results in a preferable result from the viewpoint of converting circularly polarized light obliquely incident on the λ/4 plate into linearly polarized light.

Here, the λ/4 plate is disposed in such a manner as to match the slow axis so that the other circularly polarized light (circularly polarized light in the rotation direction of the transmissive cholesteric liquid crystal layer) which has passed through and entered the cholesteric liquid crystal layer 18 becomes linearly polarized light.

(Linear polarizer)

The linearly polarizing plate constituting the circularly polarizing plate has a polarizing axis in one direction and has a function of transmitting a specific linearly polarized light.

As the linear polarizer, a general linear polarizer such as an absorption polarizer containing an iodine compound or a reflection polarizer such as a metal grid can be used. In addition, the polarization axis is synonymous with the transmission axis.

As the absorption-type polarizing plate, for example, any of an iodine-based polarizing plate, a dye-based polarizing plate using a dichroic dye, and a polyene-based polarizing plate can be used. The iodine-based polarizing plate and the dye-based polarizing plate are generally manufactured by adsorbing iodine or a dichroic dye and stretching the adsorbed iodine or dichroic dye to polyvinyl alcohol.

Here, the linearly polarizing plate is disposed in accordance with the polarization axis so as to transmit the linearly polarized light transmitted and incident on the λ/4 plate. Thus, the combination of the linear polarizer and the λ/4 plate functions as a circularly polarizer that transmits the other circularly polarized light as linearly polarized light out of the light incident from the λ/4 plate side. That is, the combination of the λ/4 plate and the linearly polarizing plate transmits circular polarization in the direction opposite to the direction of rotation of the circular polarization reflected by the cholesteric liquid crystal layer 18.

(adhesive layer)

The adhesive layer bonds the cholesteric liquid crystal layer 18 to a lambda/4 plate (circularly polarizing plate).

The pressure-sensitive adhesive layer may be a layer including a pressure-sensitive adhesive, which has fluidity and then becomes solid at the time of bonding, a layer including a pressure-sensitive adhesive, which is a soft solid in a gel state (rubber-like) at the time of bonding and whose state in the gel state does not change thereafter, or a layer including a material having characteristics of both a pressure-sensitive adhesive and a pressure-sensitive adhesive, as long as the layer (sheet-like material) to be bonded is bonded. Therefore, a known adhesive layer for bonding a sheet-like object, such as an Optically Clear Adhesive (OCA), an optically clear double-sided tape, or an ultraviolet curable resin, may be used as the adhesive layer.

[ use ]

The application of the liquid crystal film of the present invention is not particularly limited, and for example, an advertisement medium pasted on a window glass of a building, an advertisement medium pasted on a window glass of a car, a taxi, a bus, a train, or the like, a lighting part or a design decoration, a road sign, a window glass of a house, a shop, an aquarium, an zoo, a garden, a plant, an art gallery, or the like, a toy such as a game machine, a game card, a mat, a toy, a stationery, a stage, a theater equipment, a transparent member such as an elevator, an escalator, or a staircase, a bag, a garment, a fashion member such as a goggle or sunglasses, an interior decoration material such as a wall, a curtain, a floor, or the like, a POP advertisement (Point of purchase timing advertisement), a business card, a postcard, a photo, a cup mat, a ticket, a round fan, a folding fan, a tent, a louver, a shutter, a protection screen, a screen, or the like can be used Home appliances (camera, instant camera, PC (personal computer), smart phone, television, recorder, measurement facility, audio player, game machine, VR (virtual reality) headphone, vacuum cleaner, washing machine), smart phone cover, stuffed toy, cup, dish, plate, pot, vase, table, chair, CD (compact disc), DVD box, book, calendar, plastic bottle, food packaging container, musical instruments such as guitar and piano, racket, bat, club, ball, sports goods such as ball, maze, roller coaster, scenic spot such as roller coaster, ghost house, artificial flower, educational toy, game such as chess, umbrella, cane, watch, music box, clothing material such as necklace, container of cosmetics, solar cell panel, electric lamp, and lamp cover.

The liquid crystal film of the present invention has been described in detail above, but the present invention is not limited to the above-described embodiments, and various improvements and modifications can be made without departing from the scope of the present invention.

Examples

The following examples are provided to further specifically illustrate the features of the present invention. The materials, reagents, amounts used, ratios, processing contents, processing steps and the like shown in the following examples can be appropriately modified within a range not departing from the gist of the present invention. Therefore, the scope of the present invention is not to be construed in a limiting sense based on the examples shown below.

[ example 1]

As example 1, a liquid crystal film was produced using the production apparatus 100a having the structure shown in fig. 1.

(preparation of liquid Crystal composition)

In a container kept at 25 ℃, the following compositions were stirred and dissolved to prepare cholesteric liquid crystal oil ink a (liquid crystal composition).

[ chemical formula 5]

[ chemical formula 6]

[ chemical formula 7]

(formation of cholesteric liquid Crystal layer)

As the support 12a, a PET film made by Fujifilm Corporation having a thickness of 50 μm was used. A pattern mask is formed by color printing a predetermined pattern on the back surface of the support 12 a.

In the coating step, the cholesteric liquid crystal ink a prepared as described above was coated on the surface of a support using a die coater. The thickness of the dried coating layer is adjusted to about 2 to 5 μm, and the coating is performed at room temperature to form a coating film.

Next, as an irradiation step, 50mJ/cm was applied to the coating film through a pattern mask at room temperature²UV (ultraviolet, wavelength 365nm) irradiation. In addition, LEDUVHLDL-200X180-U6PSC (manufactured by CCS Inc.) was used as a light source for UV irradiation.

Next, as a heating step, the support on which the coating film after the irradiation step was laminated was heated in a hot air drying zone at 90 ℃ for 1 minute.

Next, as a curing step, UV irradiation (wavelength of 300 to 350nm, 200 mJ/cm) is performed from the surface to the coating film after the heat treatment at room temperature in a nitrogen atmosphere (oxygen concentration of 500ppm or less)²) The coating film is cured to form a cholesteric liquid crystal layer.

Further, as a light source for UV irradiation, UE0961-426-05CQT (IWASAKI ELECTRIC co., ltd).

Then, the steel sheet was wound up by a winding roll.

[ example 2]

As example 2, a liquid crystal film was produced using the production apparatus 100b having the structure shown in fig. 3.

Specifically, a liquid crystal film was produced in the same manner as in example 1 except that a PET film made by Fujifilm Corporation having a thickness of 50 μm was used as the support 12b, a pattern mask (ink layer 22) was formed by color printing a predetermined pattern on the base film 20 (a PET film made by ltd. having a thickness of 100 μm TOYOBO co., before the coating step) as the mask film 14, the mask film 14 was attached to the support 12b before the coating step, and the mask film 14 was peeled off after the curing step.

In addition, the mask film 14 attaches the pattern mask side to the support 12 b.

[ example 3]

A liquid crystal film was produced in the same manner as in example 2, except that the base film 20 side of the mask film 14 was attached to the support 12 b.

[ example 4]

In the irradiation step, 2 irradiations were performed, and the dose in the first irradiation step was set to 20mJ/cm²And the irradiation amount in the second irradiation step was set to 40mJ/cm²Except for this, a liquid crystal film was produced in the same manner as in example 1.

[ example 5]

The dose of the first irradiation step was set to 50mJ/cm²And the irradiation amount in the second irradiation step is set to 100mJ/cm²Except for this, a liquid crystal film was produced in the same manner as in example 4.

[ example 6]

The wavelength of light in the first irradiation step was 385nm, and the irradiation dose was 50mJ/cm²The wavelength in the second irradiation step was 365nm, and the dose was 50mJ/cm²Except for this, a liquid crystal film was produced in the same manner as in example 4.

[ example 7]

The dose of the first irradiation step was set to 125mJ/cm²And the irradiation amount in the second irradiation step was set to 125mJ/cm²Except for this, a liquid crystal film was produced in the same manner as in example 4.

[ example 8]

A liquid crystal film was produced in the same manner as in example 1, except that 40mg of IRGACURE 369 (manufactured by BASF) was used as an initiator contained in the liquid crystal composition (cholesteric liquid crystal ink a) and the wavelength of light in the curing step was 365 nm.

Comparative example 1

A liquid crystal film was produced in the same manner as in example 1, except that the alignment step was followed by the irradiation step.

Comparative example 2

A liquid crystal film was produced in the same manner as in example 1, except that a black/white binary pattern mask was formed on the support by printing as a pattern mask.

Comparative example 3

A liquid crystal film was produced in the same manner as in example 2, except that a black/white binary pattern mask was formed on the support by printing as a pattern mask.

< evaluation >

The liquid crystal films produced in the examples were visually observed from the cholesteric liquid crystal layer side, and the fineness of the pattern and the gradation of color display were evaluated by the following criteria.

Evaluation of fineness of Pattern

AA: is very good

A: good effect

B: slightly good

C: the pattern is blurred.

Evaluation of gradation of color display

A: has high gray scale

B: slightly higher gray scale

C: 2-ary or chroma blur.

The results are shown in Table 1.

Fig. 8 shows an image obtained by imaging the pattern mask of example 1, and fig. 7 shows an image obtained by imaging the liquid crystal film produced in example 1. In the present invention, the same effect can be obtained even with the pattern mask having the gradation shown in fig. 6. Then, a part of the liquid crystal film shown in fig. 7 was cut out for evaluation.

Fig. 9 shows images of the 2-element masks used in comparative examples 2 and 3.

As shown in table 1, it is understood that the liquid crystal films of examples 1 to 8 produced by the production method of the present invention are superior in fineness and gradation to those of comparative examples.

As is clear from a comparison between example 2 and example 3, when the pattern mask is formed into a thin film different from the support and is attached to the support to perform the irradiation step, it is preferable to attach the pattern mask side to the support.

Further, as is clear from comparison of example 1 with examples 5 and 6, the fineness is further improved by irradiating light twice in the irradiation step.

Further, as is clear from comparison between examples 5 and 6 and example 7, the total irradiation dose is preferably 200mJ/cm²The following.

As is clear from comparison between example 1 and example 8, the wavelength of the light in the irradiation step is preferably different from the wavelength of the light in the curing step.

[ example 9]

A liquid crystal film was produced in the same manner as in example 1, except that the pattern mask shown in fig. 10 was used as example 9. Fig. 11 shows an image obtained by imaging the produced liquid crystal film.

As is clear from fig. 10 and 11, the regions having different colors, i.e., selective reflection wavelengths of the cholesteric liquid crystal layer are formed according to the pattern and the shade of the pattern mask.

The effects of the present invention can be seen from the above results.

Description of the symbols

12a, 12 b-support, 14-mask film, 16-circularly polarizing plate, 18-cholesteric liquid crystal layer, 20-substrate film, 21 a-coating film, 21 b-coating film after exposure, 21 c-oriented coating film, 22-ink layer, 23a to 23d, 25a to 25 b-laminated film, 100a, 100 b-liquid crystal film manufacturing apparatus, 102-conveying roller, 104-coating nozzle, 106, 114-supporting roller, 108-exposure apparatus, 110-heating apparatus, 112-UV irradiation apparatus, 116-take-up roller, 120-1 st conveying section, 122-2 nd conveying section, 124-3 rd conveying section, 130, 132, 142, 146-roller, 140-supplying roller, 144-recovery roller, 150-coating section, 152-an exposure section, 154-a heating section, 156-a curing section.

Claims

1. A method for manufacturing a liquid crystal film, comprising the steps of:

an irradiation step of irradiating the coating film of the liquid crystal composition in an undried state with light having a wavelength to which the chiral agent is sensitive;

an alignment step of heating the coating film to align the liquid crystal; and

a curing step of curing the oriented coating film,

the pattern mask is a multi-tone pattern mask having 3 or more regions having different transmittances with respect to light of a wavelength to which the chiral agent is exposed,

in the irradiating step, the coating film is irradiated with light through the multi-tone pattern mask, thereby irradiating different amounts of light to the respective regions of the coating film, and thereby varying the amount of change in the structural change of the chiral agent in each of the regions.

2. The method for producing a liquid crystal film according to claim 1,

the pattern mask is formed on the back surface of the support.

3. The method for producing a liquid crystal film according to claim 1,

the pattern mask is formed on the surface of the long-sized substrate film,

in the irradiation step, light irradiation is performed in a state where the base film on which the pattern mask is formed is attached to the back surface of the support.

4. The method for producing a liquid crystal film according to any one of claims 1 to 3,

the pattern mask is formed by gray scale printing.

5. The method for producing a liquid crystal film according to any one of claims 1 to 3,

the irradiation step includes a first irradiation step and a second irradiation step,

6. The method for producing a liquid crystal film according to claim 5,

the first irradiation step and the second irradiation stepThe total dose of the irradiation step was 200mJ/cm²The following.

7. The method for producing a liquid crystal film according to any one of claims 1 to 3,

8. The method for producing a liquid crystal film according to any one of claims 1 to 3,

the curing step is a step of photocuring the coating film,

9. The method for producing a liquid crystal film according to claim 8,

in the curing step, the pattern mask is integrally conveyed in a state of being disposed on the back surface side of the support,

light is irradiated to a surface side opposite to the pattern mask.

10. The method for producing a liquid crystal film according to any one of claims 1 to 3,

the method for applying the liquid crystal composition in the application step is bar coating.

11. The method for producing a liquid crystal film according to any one of claims 1 to 3,

repeating the combination of the coating step, the irradiation step, the alignment step, and the curing step 2 or more times to form 2 or more cholesteric liquid crystal layers,

in the irradiation steps 2 or more times, light is irradiated through the pattern mask having the same pattern, and the irradiation amounts of light in the irradiation steps are made different from each other.

12. A method for producing a functional film, comprising: a step of attaching a circularly polarizing plate to the surface of the cured coating film or the back surface of the support after the curing step in the method for producing a liquid crystal film according to any one of claims 1 to 3.